1 //===- InstructionCombining.cpp - Combine multiple instructions -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // InstructionCombining - Combine instructions to form fewer, simple
11 // instructions. This pass does not modify the CFG. This pass is where
12 // algebraic simplification happens.
14 // This pass combines things like:
20 // This is a simple worklist driven algorithm.
22 // This pass guarantees that the following canonicalizations are performed on
24 // 1. If a binary operator has a constant operand, it is moved to the RHS
25 // 2. Bitwise operators with constant operands are always grouped so that
26 // shifts are performed first, then or's, then and's, then xor's.
27 // 3. Compare instructions are converted from <,>,<=,>= to ==,!= if possible
28 // 4. All cmp instructions on boolean values are replaced with logical ops
29 // 5. add X, X is represented as (X*2) => (X << 1)
30 // 6. Multiplies with a power-of-two constant argument are transformed into
34 //===----------------------------------------------------------------------===//
36 #define DEBUG_TYPE "instcombine"
37 #include "llvm/Transforms/Scalar.h"
38 #include "llvm/IntrinsicInst.h"
39 #include "llvm/LLVMContext.h"
40 #include "llvm/Pass.h"
41 #include "llvm/DerivedTypes.h"
42 #include "llvm/GlobalVariable.h"
43 #include "llvm/Operator.h"
44 #include "llvm/Analysis/ConstantFolding.h"
45 #include "llvm/Analysis/MallocHelper.h"
46 #include "llvm/Analysis/ValueTracking.h"
47 #include "llvm/Target/TargetData.h"
48 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
49 #include "llvm/Transforms/Utils/Local.h"
50 #include "llvm/Support/CallSite.h"
51 #include "llvm/Support/ConstantRange.h"
52 #include "llvm/Support/Debug.h"
53 #include "llvm/Support/ErrorHandling.h"
54 #include "llvm/Support/GetElementPtrTypeIterator.h"
55 #include "llvm/Support/InstVisitor.h"
56 #include "llvm/Support/IRBuilder.h"
57 #include "llvm/Support/MathExtras.h"
58 #include "llvm/Support/PatternMatch.h"
59 #include "llvm/Support/TargetFolder.h"
60 #include "llvm/Support/raw_ostream.h"
61 #include "llvm/ADT/DenseMap.h"
62 #include "llvm/ADT/SmallVector.h"
63 #include "llvm/ADT/SmallPtrSet.h"
64 #include "llvm/ADT/Statistic.h"
65 #include "llvm/ADT/STLExtras.h"
69 using namespace llvm::PatternMatch;
71 STATISTIC(NumCombined , "Number of insts combined");
72 STATISTIC(NumConstProp, "Number of constant folds");
73 STATISTIC(NumDeadInst , "Number of dead inst eliminated");
74 STATISTIC(NumDeadStore, "Number of dead stores eliminated");
75 STATISTIC(NumSunkInst , "Number of instructions sunk");
78 /// InstCombineWorklist - This is the worklist management logic for
80 class InstCombineWorklist {
81 SmallVector<Instruction*, 256> Worklist;
82 DenseMap<Instruction*, unsigned> WorklistMap;
84 void operator=(const InstCombineWorklist&RHS); // DO NOT IMPLEMENT
85 InstCombineWorklist(const InstCombineWorklist&); // DO NOT IMPLEMENT
87 InstCombineWorklist() {}
89 bool isEmpty() const { return Worklist.empty(); }
91 /// Add - Add the specified instruction to the worklist if it isn't already
93 void Add(Instruction *I) {
94 if (WorklistMap.insert(std::make_pair(I, Worklist.size())).second) {
95 DEBUG(errs() << "IC: ADD: " << *I << '\n');
96 Worklist.push_back(I);
100 void AddValue(Value *V) {
101 if (Instruction *I = dyn_cast<Instruction>(V))
105 /// AddInitialGroup - Add the specified batch of stuff in reverse order.
106 /// which should only be done when the worklist is empty and when the group
107 /// has no duplicates.
108 void AddInitialGroup(Instruction *const *List, unsigned NumEntries) {
109 assert(Worklist.empty() && "Worklist must be empty to add initial group");
110 Worklist.reserve(NumEntries+16);
111 DEBUG(errs() << "IC: ADDING: " << NumEntries << " instrs to worklist\n");
112 for (; NumEntries; --NumEntries) {
113 Instruction *I = List[NumEntries-1];
114 WorklistMap.insert(std::make_pair(I, Worklist.size()));
115 Worklist.push_back(I);
119 // Remove - remove I from the worklist if it exists.
120 void Remove(Instruction *I) {
121 DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I);
122 if (It == WorklistMap.end()) return; // Not in worklist.
124 // Don't bother moving everything down, just null out the slot.
125 Worklist[It->second] = 0;
127 WorklistMap.erase(It);
130 Instruction *RemoveOne() {
131 Instruction *I = Worklist.back();
133 WorklistMap.erase(I);
137 /// AddUsersToWorkList - When an instruction is simplified, add all users of
138 /// the instruction to the work lists because they might get more simplified
141 void AddUsersToWorkList(Instruction &I) {
142 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
144 Add(cast<Instruction>(*UI));
148 /// Zap - check that the worklist is empty and nuke the backing store for
149 /// the map if it is large.
151 assert(WorklistMap.empty() && "Worklist empty, but map not?");
153 // Do an explicit clear, this shrinks the map if needed.
157 } // end anonymous namespace.
161 /// InstCombineIRInserter - This is an IRBuilder insertion helper that works
162 /// just like the normal insertion helper, but also adds any new instructions
163 /// to the instcombine worklist.
164 class InstCombineIRInserter : public IRBuilderDefaultInserter<true> {
165 InstCombineWorklist &Worklist;
167 InstCombineIRInserter(InstCombineWorklist &WL) : Worklist(WL) {}
169 void InsertHelper(Instruction *I, const Twine &Name,
170 BasicBlock *BB, BasicBlock::iterator InsertPt) const {
171 IRBuilderDefaultInserter<true>::InsertHelper(I, Name, BB, InsertPt);
175 } // end anonymous namespace
179 class InstCombiner : public FunctionPass,
180 public InstVisitor<InstCombiner, Instruction*> {
182 bool MustPreserveLCSSA;
185 /// Worklist - All of the instructions that need to be simplified.
186 InstCombineWorklist Worklist;
188 /// Builder - This is an IRBuilder that automatically inserts new
189 /// instructions into the worklist when they are created.
190 typedef IRBuilder<true, TargetFolder, InstCombineIRInserter> BuilderTy;
193 static char ID; // Pass identification, replacement for typeid
194 InstCombiner() : FunctionPass(&ID), TD(0), Builder(0) {}
196 LLVMContext *Context;
197 LLVMContext *getContext() const { return Context; }
200 virtual bool runOnFunction(Function &F);
202 bool DoOneIteration(Function &F, unsigned ItNum);
204 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
205 AU.addPreservedID(LCSSAID);
206 AU.setPreservesCFG();
209 TargetData *getTargetData() const { return TD; }
211 // Visitation implementation - Implement instruction combining for different
212 // instruction types. The semantics are as follows:
214 // null - No change was made
215 // I - Change was made, I is still valid, I may be dead though
216 // otherwise - Change was made, replace I with returned instruction
218 Instruction *visitAdd(BinaryOperator &I);
219 Instruction *visitFAdd(BinaryOperator &I);
220 Instruction *visitSub(BinaryOperator &I);
221 Instruction *visitFSub(BinaryOperator &I);
222 Instruction *visitMul(BinaryOperator &I);
223 Instruction *visitFMul(BinaryOperator &I);
224 Instruction *visitURem(BinaryOperator &I);
225 Instruction *visitSRem(BinaryOperator &I);
226 Instruction *visitFRem(BinaryOperator &I);
227 bool SimplifyDivRemOfSelect(BinaryOperator &I);
228 Instruction *commonRemTransforms(BinaryOperator &I);
229 Instruction *commonIRemTransforms(BinaryOperator &I);
230 Instruction *commonDivTransforms(BinaryOperator &I);
231 Instruction *commonIDivTransforms(BinaryOperator &I);
232 Instruction *visitUDiv(BinaryOperator &I);
233 Instruction *visitSDiv(BinaryOperator &I);
234 Instruction *visitFDiv(BinaryOperator &I);
235 Instruction *FoldAndOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS);
236 Instruction *FoldAndOfFCmps(Instruction &I, FCmpInst *LHS, FCmpInst *RHS);
237 Instruction *visitAnd(BinaryOperator &I);
238 Instruction *FoldOrOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS);
239 Instruction *FoldOrOfFCmps(Instruction &I, FCmpInst *LHS, FCmpInst *RHS);
240 Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op,
241 Value *A, Value *B, Value *C);
242 Instruction *visitOr (BinaryOperator &I);
243 Instruction *visitXor(BinaryOperator &I);
244 Instruction *visitShl(BinaryOperator &I);
245 Instruction *visitAShr(BinaryOperator &I);
246 Instruction *visitLShr(BinaryOperator &I);
247 Instruction *commonShiftTransforms(BinaryOperator &I);
248 Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI,
250 Instruction *visitFCmpInst(FCmpInst &I);
251 Instruction *visitICmpInst(ICmpInst &I);
252 Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
253 Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
256 Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
257 ConstantInt *DivRHS);
259 Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
260 ICmpInst::Predicate Cond, Instruction &I);
261 Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
263 Instruction *commonCastTransforms(CastInst &CI);
264 Instruction *commonIntCastTransforms(CastInst &CI);
265 Instruction *commonPointerCastTransforms(CastInst &CI);
266 Instruction *visitTrunc(TruncInst &CI);
267 Instruction *visitZExt(ZExtInst &CI);
268 Instruction *visitSExt(SExtInst &CI);
269 Instruction *visitFPTrunc(FPTruncInst &CI);
270 Instruction *visitFPExt(CastInst &CI);
271 Instruction *visitFPToUI(FPToUIInst &FI);
272 Instruction *visitFPToSI(FPToSIInst &FI);
273 Instruction *visitUIToFP(CastInst &CI);
274 Instruction *visitSIToFP(CastInst &CI);
275 Instruction *visitPtrToInt(PtrToIntInst &CI);
276 Instruction *visitIntToPtr(IntToPtrInst &CI);
277 Instruction *visitBitCast(BitCastInst &CI);
278 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
280 Instruction *FoldSelectIntoOp(SelectInst &SI, Value*, Value*);
281 Instruction *visitSelectInst(SelectInst &SI);
282 Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
283 Instruction *visitCallInst(CallInst &CI);
284 Instruction *visitInvokeInst(InvokeInst &II);
285 Instruction *visitPHINode(PHINode &PN);
286 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
287 Instruction *visitAllocationInst(AllocationInst &AI);
288 Instruction *visitFreeInst(FreeInst &FI);
289 Instruction *visitLoadInst(LoadInst &LI);
290 Instruction *visitStoreInst(StoreInst &SI);
291 Instruction *visitBranchInst(BranchInst &BI);
292 Instruction *visitSwitchInst(SwitchInst &SI);
293 Instruction *visitInsertElementInst(InsertElementInst &IE);
294 Instruction *visitExtractElementInst(ExtractElementInst &EI);
295 Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
296 Instruction *visitExtractValueInst(ExtractValueInst &EV);
298 // visitInstruction - Specify what to return for unhandled instructions...
299 Instruction *visitInstruction(Instruction &I) { return 0; }
302 Instruction *visitCallSite(CallSite CS);
303 bool transformConstExprCastCall(CallSite CS);
304 Instruction *transformCallThroughTrampoline(CallSite CS);
305 Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI,
306 bool DoXform = true);
307 bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS);
308 DbgDeclareInst *hasOneUsePlusDeclare(Value *V);
312 // InsertNewInstBefore - insert an instruction New before instruction Old
313 // in the program. Add the new instruction to the worklist.
315 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
316 assert(New && New->getParent() == 0 &&
317 "New instruction already inserted into a basic block!");
318 BasicBlock *BB = Old.getParent();
319 BB->getInstList().insert(&Old, New); // Insert inst
324 // ReplaceInstUsesWith - This method is to be used when an instruction is
325 // found to be dead, replacable with another preexisting expression. Here
326 // we add all uses of I to the worklist, replace all uses of I with the new
327 // value, then return I, so that the inst combiner will know that I was
330 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
331 Worklist.AddUsersToWorkList(I); // Add all modified instrs to worklist.
333 // If we are replacing the instruction with itself, this must be in a
334 // segment of unreachable code, so just clobber the instruction.
336 V = UndefValue::get(I.getType());
338 I.replaceAllUsesWith(V);
342 // EraseInstFromFunction - When dealing with an instruction that has side
343 // effects or produces a void value, we can't rely on DCE to delete the
344 // instruction. Instead, visit methods should return the value returned by
346 Instruction *EraseInstFromFunction(Instruction &I) {
347 DEBUG(errs() << "IC: ERASE " << I << '\n');
349 assert(I.use_empty() && "Cannot erase instruction that is used!");
350 // Make sure that we reprocess all operands now that we reduced their
352 if (I.getNumOperands() < 8) {
353 for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i)
354 if (Instruction *Op = dyn_cast<Instruction>(*i))
360 return 0; // Don't do anything with FI
363 void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero,
364 APInt &KnownOne, unsigned Depth = 0) const {
365 return llvm::ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth);
368 bool MaskedValueIsZero(Value *V, const APInt &Mask,
369 unsigned Depth = 0) const {
370 return llvm::MaskedValueIsZero(V, Mask, TD, Depth);
372 unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0) const {
373 return llvm::ComputeNumSignBits(Op, TD, Depth);
378 /// SimplifyCommutative - This performs a few simplifications for
379 /// commutative operators.
380 bool SimplifyCommutative(BinaryOperator &I);
382 /// SimplifyCompare - This reorders the operands of a CmpInst to get them in
383 /// most-complex to least-complex order.
384 bool SimplifyCompare(CmpInst &I);
386 /// SimplifyDemandedUseBits - Attempts to replace V with a simpler value
387 /// based on the demanded bits.
388 Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
389 APInt& KnownZero, APInt& KnownOne,
391 bool SimplifyDemandedBits(Use &U, APInt DemandedMask,
392 APInt& KnownZero, APInt& KnownOne,
395 /// SimplifyDemandedInstructionBits - Inst is an integer instruction that
396 /// SimplifyDemandedBits knows about. See if the instruction has any
397 /// properties that allow us to simplify its operands.
398 bool SimplifyDemandedInstructionBits(Instruction &Inst);
400 Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
401 APInt& UndefElts, unsigned Depth = 0);
403 // FoldOpIntoPhi - Given a binary operator, cast instruction, or select
404 // which has a PHI node as operand #0, see if we can fold the instruction
405 // into the PHI (which is only possible if all operands to the PHI are
408 // If AllowAggressive is true, FoldOpIntoPhi will allow certain transforms
409 // that would normally be unprofitable because they strongly encourage jump
411 Instruction *FoldOpIntoPhi(Instruction &I, bool AllowAggressive = false);
413 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
414 // operator and they all are only used by the PHI, PHI together their
415 // inputs, and do the operation once, to the result of the PHI.
416 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
417 Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
418 Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN);
421 Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
422 ConstantInt *AndRHS, BinaryOperator &TheAnd);
424 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
425 bool isSub, Instruction &I);
426 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
427 bool isSigned, bool Inside, Instruction &IB);
428 Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocationInst &AI);
429 Instruction *MatchBSwap(BinaryOperator &I);
430 bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
431 Instruction *SimplifyMemTransfer(MemIntrinsic *MI);
432 Instruction *SimplifyMemSet(MemSetInst *MI);
435 Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned);
437 bool CanEvaluateInDifferentType(Value *V, const Type *Ty,
438 unsigned CastOpc, int &NumCastsRemoved);
439 unsigned GetOrEnforceKnownAlignment(Value *V,
440 unsigned PrefAlign = 0);
443 } // end anonymous namespace
445 char InstCombiner::ID = 0;
446 static RegisterPass<InstCombiner>
447 X("instcombine", "Combine redundant instructions");
449 // getComplexity: Assign a complexity or rank value to LLVM Values...
450 // 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
451 static unsigned getComplexity(Value *V) {
452 if (isa<Instruction>(V)) {
453 if (BinaryOperator::isNeg(V) ||
454 BinaryOperator::isFNeg(V) ||
455 BinaryOperator::isNot(V))
459 if (isa<Argument>(V)) return 3;
460 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
463 // isOnlyUse - Return true if this instruction will be deleted if we stop using
465 static bool isOnlyUse(Value *V) {
466 return V->hasOneUse() || isa<Constant>(V);
469 // getPromotedType - Return the specified type promoted as it would be to pass
470 // though a va_arg area...
471 static const Type *getPromotedType(const Type *Ty) {
472 if (const IntegerType* ITy = dyn_cast<IntegerType>(Ty)) {
473 if (ITy->getBitWidth() < 32)
474 return Type::getInt32Ty(Ty->getContext());
479 /// getBitCastOperand - If the specified operand is a CastInst, a constant
480 /// expression bitcast, or a GetElementPtrInst with all zero indices, return the
481 /// operand value, otherwise return null.
482 static Value *getBitCastOperand(Value *V) {
483 if (Operator *O = dyn_cast<Operator>(V)) {
484 if (O->getOpcode() == Instruction::BitCast)
485 return O->getOperand(0);
486 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
487 if (GEP->hasAllZeroIndices())
488 return GEP->getPointerOperand();
493 /// This function is a wrapper around CastInst::isEliminableCastPair. It
494 /// simply extracts arguments and returns what that function returns.
495 static Instruction::CastOps
496 isEliminableCastPair(
497 const CastInst *CI, ///< The first cast instruction
498 unsigned opcode, ///< The opcode of the second cast instruction
499 const Type *DstTy, ///< The target type for the second cast instruction
500 TargetData *TD ///< The target data for pointer size
503 const Type *SrcTy = CI->getOperand(0)->getType(); // A from above
504 const Type *MidTy = CI->getType(); // B from above
506 // Get the opcodes of the two Cast instructions
507 Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode());
508 Instruction::CastOps secondOp = Instruction::CastOps(opcode);
510 unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
512 TD ? TD->getIntPtrType(CI->getContext()) : 0);
514 // We don't want to form an inttoptr or ptrtoint that converts to an integer
515 // type that differs from the pointer size.
516 if ((Res == Instruction::IntToPtr &&
517 (!TD || SrcTy != TD->getIntPtrType(CI->getContext()))) ||
518 (Res == Instruction::PtrToInt &&
519 (!TD || DstTy != TD->getIntPtrType(CI->getContext()))))
522 return Instruction::CastOps(Res);
525 /// ValueRequiresCast - Return true if the cast from "V to Ty" actually results
526 /// in any code being generated. It does not require codegen if V is simple
527 /// enough or if the cast can be folded into other casts.
528 static bool ValueRequiresCast(Instruction::CastOps opcode, const Value *V,
529 const Type *Ty, TargetData *TD) {
530 if (V->getType() == Ty || isa<Constant>(V)) return false;
532 // If this is another cast that can be eliminated, it isn't codegen either.
533 if (const CastInst *CI = dyn_cast<CastInst>(V))
534 if (isEliminableCastPair(CI, opcode, Ty, TD))
539 // SimplifyCommutative - This performs a few simplifications for commutative
542 // 1. Order operands such that they are listed from right (least complex) to
543 // left (most complex). This puts constants before unary operators before
546 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
547 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
549 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
550 bool Changed = false;
551 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
552 Changed = !I.swapOperands();
554 if (!I.isAssociative()) return Changed;
555 Instruction::BinaryOps Opcode = I.getOpcode();
556 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
557 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
558 if (isa<Constant>(I.getOperand(1))) {
559 Constant *Folded = ConstantExpr::get(I.getOpcode(),
560 cast<Constant>(I.getOperand(1)),
561 cast<Constant>(Op->getOperand(1)));
562 I.setOperand(0, Op->getOperand(0));
563 I.setOperand(1, Folded);
565 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
566 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
567 isOnlyUse(Op) && isOnlyUse(Op1)) {
568 Constant *C1 = cast<Constant>(Op->getOperand(1));
569 Constant *C2 = cast<Constant>(Op1->getOperand(1));
571 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
572 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
573 Instruction *New = BinaryOperator::Create(Opcode, Op->getOperand(0),
577 I.setOperand(0, New);
578 I.setOperand(1, Folded);
585 /// SimplifyCompare - For a CmpInst this function just orders the operands
586 /// so that theyare listed from right (least complex) to left (most complex).
587 /// This puts constants before unary operators before binary operators.
588 bool InstCombiner::SimplifyCompare(CmpInst &I) {
589 if (getComplexity(I.getOperand(0)) >= getComplexity(I.getOperand(1)))
592 // Compare instructions are not associative so there's nothing else we can do.
596 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
597 // if the LHS is a constant zero (which is the 'negate' form).
599 static inline Value *dyn_castNegVal(Value *V) {
600 if (BinaryOperator::isNeg(V))
601 return BinaryOperator::getNegArgument(V);
603 // Constants can be considered to be negated values if they can be folded.
604 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
605 return ConstantExpr::getNeg(C);
607 if (ConstantVector *C = dyn_cast<ConstantVector>(V))
608 if (C->getType()->getElementType()->isInteger())
609 return ConstantExpr::getNeg(C);
614 // dyn_castFNegVal - Given a 'fsub' instruction, return the RHS of the
615 // instruction if the LHS is a constant negative zero (which is the 'negate'
618 static inline Value *dyn_castFNegVal(Value *V) {
619 if (BinaryOperator::isFNeg(V))
620 return BinaryOperator::getFNegArgument(V);
622 // Constants can be considered to be negated values if they can be folded.
623 if (ConstantFP *C = dyn_cast<ConstantFP>(V))
624 return ConstantExpr::getFNeg(C);
626 if (ConstantVector *C = dyn_cast<ConstantVector>(V))
627 if (C->getType()->getElementType()->isFloatingPoint())
628 return ConstantExpr::getFNeg(C);
633 static inline Value *dyn_castNotVal(Value *V) {
634 if (BinaryOperator::isNot(V))
635 return BinaryOperator::getNotArgument(V);
637 // Constants can be considered to be not'ed values...
638 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
639 return ConstantInt::get(C->getType(), ~C->getValue());
643 // dyn_castFoldableMul - If this value is a multiply that can be folded into
644 // other computations (because it has a constant operand), return the
645 // non-constant operand of the multiply, and set CST to point to the multiplier.
646 // Otherwise, return null.
648 static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
649 if (V->hasOneUse() && V->getType()->isInteger())
650 if (Instruction *I = dyn_cast<Instruction>(V)) {
651 if (I->getOpcode() == Instruction::Mul)
652 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
653 return I->getOperand(0);
654 if (I->getOpcode() == Instruction::Shl)
655 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
656 // The multiplier is really 1 << CST.
657 uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
658 uint32_t CSTVal = CST->getLimitedValue(BitWidth);
659 CST = ConstantInt::get(V->getType()->getContext(),
660 APInt(BitWidth, 1).shl(CSTVal));
661 return I->getOperand(0);
667 /// AddOne - Add one to a ConstantInt
668 static Constant *AddOne(Constant *C) {
669 return ConstantExpr::getAdd(C,
670 ConstantInt::get(C->getType(), 1));
672 /// SubOne - Subtract one from a ConstantInt
673 static Constant *SubOne(ConstantInt *C) {
674 return ConstantExpr::getSub(C,
675 ConstantInt::get(C->getType(), 1));
677 /// MultiplyOverflows - True if the multiply can not be expressed in an int
679 static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
680 uint32_t W = C1->getBitWidth();
681 APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
690 APInt MulExt = LHSExt * RHSExt;
693 APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
694 APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
695 return MulExt.slt(Min) || MulExt.sgt(Max);
697 return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
701 /// ShrinkDemandedConstant - Check to see if the specified operand of the
702 /// specified instruction is a constant integer. If so, check to see if there
703 /// are any bits set in the constant that are not demanded. If so, shrink the
704 /// constant and return true.
705 static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo,
707 assert(I && "No instruction?");
708 assert(OpNo < I->getNumOperands() && "Operand index too large");
710 // If the operand is not a constant integer, nothing to do.
711 ConstantInt *OpC = dyn_cast<ConstantInt>(I->getOperand(OpNo));
712 if (!OpC) return false;
714 // If there are no bits set that aren't demanded, nothing to do.
715 Demanded.zextOrTrunc(OpC->getValue().getBitWidth());
716 if ((~Demanded & OpC->getValue()) == 0)
719 // This instruction is producing bits that are not demanded. Shrink the RHS.
720 Demanded &= OpC->getValue();
721 I->setOperand(OpNo, ConstantInt::get(OpC->getType(), Demanded));
725 // ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a
726 // set of known zero and one bits, compute the maximum and minimum values that
727 // could have the specified known zero and known one bits, returning them in
729 static void ComputeSignedMinMaxValuesFromKnownBits(const APInt& KnownZero,
730 const APInt& KnownOne,
731 APInt& Min, APInt& Max) {
732 assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
733 KnownZero.getBitWidth() == Min.getBitWidth() &&
734 KnownZero.getBitWidth() == Max.getBitWidth() &&
735 "KnownZero, KnownOne and Min, Max must have equal bitwidth.");
736 APInt UnknownBits = ~(KnownZero|KnownOne);
738 // The minimum value is when all unknown bits are zeros, EXCEPT for the sign
739 // bit if it is unknown.
741 Max = KnownOne|UnknownBits;
743 if (UnknownBits.isNegative()) { // Sign bit is unknown
744 Min.set(Min.getBitWidth()-1);
745 Max.clear(Max.getBitWidth()-1);
749 // ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and
750 // a set of known zero and one bits, compute the maximum and minimum values that
751 // could have the specified known zero and known one bits, returning them in
753 static void ComputeUnsignedMinMaxValuesFromKnownBits(const APInt &KnownZero,
754 const APInt &KnownOne,
755 APInt &Min, APInt &Max) {
756 assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
757 KnownZero.getBitWidth() == Min.getBitWidth() &&
758 KnownZero.getBitWidth() == Max.getBitWidth() &&
759 "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
760 APInt UnknownBits = ~(KnownZero|KnownOne);
762 // The minimum value is when the unknown bits are all zeros.
764 // The maximum value is when the unknown bits are all ones.
765 Max = KnownOne|UnknownBits;
768 /// SimplifyDemandedInstructionBits - Inst is an integer instruction that
769 /// SimplifyDemandedBits knows about. See if the instruction has any
770 /// properties that allow us to simplify its operands.
771 bool InstCombiner::SimplifyDemandedInstructionBits(Instruction &Inst) {
772 unsigned BitWidth = Inst.getType()->getScalarSizeInBits();
773 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
774 APInt DemandedMask(APInt::getAllOnesValue(BitWidth));
776 Value *V = SimplifyDemandedUseBits(&Inst, DemandedMask,
777 KnownZero, KnownOne, 0);
778 if (V == 0) return false;
779 if (V == &Inst) return true;
780 ReplaceInstUsesWith(Inst, V);
784 /// SimplifyDemandedBits - This form of SimplifyDemandedBits simplifies the
785 /// specified instruction operand if possible, updating it in place. It returns
786 /// true if it made any change and false otherwise.
787 bool InstCombiner::SimplifyDemandedBits(Use &U, APInt DemandedMask,
788 APInt &KnownZero, APInt &KnownOne,
790 Value *NewVal = SimplifyDemandedUseBits(U.get(), DemandedMask,
791 KnownZero, KnownOne, Depth);
792 if (NewVal == 0) return false;
798 /// SimplifyDemandedUseBits - This function attempts to replace V with a simpler
799 /// value based on the demanded bits. When this function is called, it is known
800 /// that only the bits set in DemandedMask of the result of V are ever used
801 /// downstream. Consequently, depending on the mask and V, it may be possible
802 /// to replace V with a constant or one of its operands. In such cases, this
803 /// function does the replacement and returns true. In all other cases, it
804 /// returns false after analyzing the expression and setting KnownOne and known
805 /// to be one in the expression. KnownZero contains all the bits that are known
806 /// to be zero in the expression. These are provided to potentially allow the
807 /// caller (which might recursively be SimplifyDemandedBits itself) to simplify
808 /// the expression. KnownOne and KnownZero always follow the invariant that
809 /// KnownOne & KnownZero == 0. That is, a bit can't be both 1 and 0. Note that
810 /// the bits in KnownOne and KnownZero may only be accurate for those bits set
811 /// in DemandedMask. Note also that the bitwidth of V, DemandedMask, KnownZero
812 /// and KnownOne must all be the same.
814 /// This returns null if it did not change anything and it permits no
815 /// simplification. This returns V itself if it did some simplification of V's
816 /// operands based on the information about what bits are demanded. This returns
817 /// some other non-null value if it found out that V is equal to another value
818 /// in the context where the specified bits are demanded, but not for all users.
819 Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
820 APInt &KnownZero, APInt &KnownOne,
822 assert(V != 0 && "Null pointer of Value???");
823 assert(Depth <= 6 && "Limit Search Depth");
824 uint32_t BitWidth = DemandedMask.getBitWidth();
825 const Type *VTy = V->getType();
826 assert((TD || !isa<PointerType>(VTy)) &&
827 "SimplifyDemandedBits needs to know bit widths!");
828 assert((!TD || TD->getTypeSizeInBits(VTy->getScalarType()) == BitWidth) &&
829 (!VTy->isIntOrIntVector() ||
830 VTy->getScalarSizeInBits() == BitWidth) &&
831 KnownZero.getBitWidth() == BitWidth &&
832 KnownOne.getBitWidth() == BitWidth &&
833 "Value *V, DemandedMask, KnownZero and KnownOne "
834 "must have same BitWidth");
835 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
836 // We know all of the bits for a constant!
837 KnownOne = CI->getValue() & DemandedMask;
838 KnownZero = ~KnownOne & DemandedMask;
841 if (isa<ConstantPointerNull>(V)) {
842 // We know all of the bits for a constant!
844 KnownZero = DemandedMask;
850 if (DemandedMask == 0) { // Not demanding any bits from V.
851 if (isa<UndefValue>(V))
853 return UndefValue::get(VTy);
856 if (Depth == 6) // Limit search depth.
859 APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0);
860 APInt &RHSKnownZero = KnownZero, &RHSKnownOne = KnownOne;
862 Instruction *I = dyn_cast<Instruction>(V);
864 ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
865 return 0; // Only analyze instructions.
868 // If there are multiple uses of this value and we aren't at the root, then
869 // we can't do any simplifications of the operands, because DemandedMask
870 // only reflects the bits demanded by *one* of the users.
871 if (Depth != 0 && !I->hasOneUse()) {
872 // Despite the fact that we can't simplify this instruction in all User's
873 // context, we can at least compute the knownzero/knownone bits, and we can
874 // do simplifications that apply to *just* the one user if we know that
875 // this instruction has a simpler value in that context.
876 if (I->getOpcode() == Instruction::And) {
877 // If either the LHS or the RHS are Zero, the result is zero.
878 ComputeMaskedBits(I->getOperand(1), DemandedMask,
879 RHSKnownZero, RHSKnownOne, Depth+1);
880 ComputeMaskedBits(I->getOperand(0), DemandedMask & ~RHSKnownZero,
881 LHSKnownZero, LHSKnownOne, Depth+1);
883 // If all of the demanded bits are known 1 on one side, return the other.
884 // These bits cannot contribute to the result of the 'and' in this
886 if ((DemandedMask & ~LHSKnownZero & RHSKnownOne) ==
887 (DemandedMask & ~LHSKnownZero))
888 return I->getOperand(0);
889 if ((DemandedMask & ~RHSKnownZero & LHSKnownOne) ==
890 (DemandedMask & ~RHSKnownZero))
891 return I->getOperand(1);
893 // If all of the demanded bits in the inputs are known zeros, return zero.
894 if ((DemandedMask & (RHSKnownZero|LHSKnownZero)) == DemandedMask)
895 return Constant::getNullValue(VTy);
897 } else if (I->getOpcode() == Instruction::Or) {
898 // We can simplify (X|Y) -> X or Y in the user's context if we know that
899 // only bits from X or Y are demanded.
901 // If either the LHS or the RHS are One, the result is One.
902 ComputeMaskedBits(I->getOperand(1), DemandedMask,
903 RHSKnownZero, RHSKnownOne, Depth+1);
904 ComputeMaskedBits(I->getOperand(0), DemandedMask & ~RHSKnownOne,
905 LHSKnownZero, LHSKnownOne, Depth+1);
907 // If all of the demanded bits are known zero on one side, return the
908 // other. These bits cannot contribute to the result of the 'or' in this
910 if ((DemandedMask & ~LHSKnownOne & RHSKnownZero) ==
911 (DemandedMask & ~LHSKnownOne))
912 return I->getOperand(0);
913 if ((DemandedMask & ~RHSKnownOne & LHSKnownZero) ==
914 (DemandedMask & ~RHSKnownOne))
915 return I->getOperand(1);
917 // If all of the potentially set bits on one side are known to be set on
918 // the other side, just use the 'other' side.
919 if ((DemandedMask & (~RHSKnownZero) & LHSKnownOne) ==
920 (DemandedMask & (~RHSKnownZero)))
921 return I->getOperand(0);
922 if ((DemandedMask & (~LHSKnownZero) & RHSKnownOne) ==
923 (DemandedMask & (~LHSKnownZero)))
924 return I->getOperand(1);
927 // Compute the KnownZero/KnownOne bits to simplify things downstream.
928 ComputeMaskedBits(I, DemandedMask, KnownZero, KnownOne, Depth);
932 // If this is the root being simplified, allow it to have multiple uses,
933 // just set the DemandedMask to all bits so that we can try to simplify the
934 // operands. This allows visitTruncInst (for example) to simplify the
935 // operand of a trunc without duplicating all the logic below.
936 if (Depth == 0 && !V->hasOneUse())
937 DemandedMask = APInt::getAllOnesValue(BitWidth);
939 switch (I->getOpcode()) {
941 ComputeMaskedBits(I, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
943 case Instruction::And:
944 // If either the LHS or the RHS are Zero, the result is zero.
945 if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
946 RHSKnownZero, RHSKnownOne, Depth+1) ||
947 SimplifyDemandedBits(I->getOperandUse(0), DemandedMask & ~RHSKnownZero,
948 LHSKnownZero, LHSKnownOne, Depth+1))
950 assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
951 assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
953 // If all of the demanded bits are known 1 on one side, return the other.
954 // These bits cannot contribute to the result of the 'and'.
955 if ((DemandedMask & ~LHSKnownZero & RHSKnownOne) ==
956 (DemandedMask & ~LHSKnownZero))
957 return I->getOperand(0);
958 if ((DemandedMask & ~RHSKnownZero & LHSKnownOne) ==
959 (DemandedMask & ~RHSKnownZero))
960 return I->getOperand(1);
962 // If all of the demanded bits in the inputs are known zeros, return zero.
963 if ((DemandedMask & (RHSKnownZero|LHSKnownZero)) == DemandedMask)
964 return Constant::getNullValue(VTy);
966 // If the RHS is a constant, see if we can simplify it.
967 if (ShrinkDemandedConstant(I, 1, DemandedMask & ~LHSKnownZero))
970 // Output known-1 bits are only known if set in both the LHS & RHS.
971 RHSKnownOne &= LHSKnownOne;
972 // Output known-0 are known to be clear if zero in either the LHS | RHS.
973 RHSKnownZero |= LHSKnownZero;
975 case Instruction::Or:
976 // If either the LHS or the RHS are One, the result is One.
977 if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
978 RHSKnownZero, RHSKnownOne, Depth+1) ||
979 SimplifyDemandedBits(I->getOperandUse(0), DemandedMask & ~RHSKnownOne,
980 LHSKnownZero, LHSKnownOne, Depth+1))
982 assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
983 assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
985 // If all of the demanded bits are known zero on one side, return the other.
986 // These bits cannot contribute to the result of the 'or'.
987 if ((DemandedMask & ~LHSKnownOne & RHSKnownZero) ==
988 (DemandedMask & ~LHSKnownOne))
989 return I->getOperand(0);
990 if ((DemandedMask & ~RHSKnownOne & LHSKnownZero) ==
991 (DemandedMask & ~RHSKnownOne))
992 return I->getOperand(1);
994 // If all of the potentially set bits on one side are known to be set on
995 // the other side, just use the 'other' side.
996 if ((DemandedMask & (~RHSKnownZero) & LHSKnownOne) ==
997 (DemandedMask & (~RHSKnownZero)))
998 return I->getOperand(0);
999 if ((DemandedMask & (~LHSKnownZero) & RHSKnownOne) ==
1000 (DemandedMask & (~LHSKnownZero)))
1001 return I->getOperand(1);
1003 // If the RHS is a constant, see if we can simplify it.
1004 if (ShrinkDemandedConstant(I, 1, DemandedMask))
1007 // Output known-0 bits are only known if clear in both the LHS & RHS.
1008 RHSKnownZero &= LHSKnownZero;
1009 // Output known-1 are known to be set if set in either the LHS | RHS.
1010 RHSKnownOne |= LHSKnownOne;
1012 case Instruction::Xor: {
1013 if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
1014 RHSKnownZero, RHSKnownOne, Depth+1) ||
1015 SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
1016 LHSKnownZero, LHSKnownOne, Depth+1))
1018 assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
1019 assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
1021 // If all of the demanded bits are known zero on one side, return the other.
1022 // These bits cannot contribute to the result of the 'xor'.
1023 if ((DemandedMask & RHSKnownZero) == DemandedMask)
1024 return I->getOperand(0);
1025 if ((DemandedMask & LHSKnownZero) == DemandedMask)
1026 return I->getOperand(1);
1028 // Output known-0 bits are known if clear or set in both the LHS & RHS.
1029 APInt KnownZeroOut = (RHSKnownZero & LHSKnownZero) |
1030 (RHSKnownOne & LHSKnownOne);
1031 // Output known-1 are known to be set if set in only one of the LHS, RHS.
1032 APInt KnownOneOut = (RHSKnownZero & LHSKnownOne) |
1033 (RHSKnownOne & LHSKnownZero);
1035 // If all of the demanded bits are known to be zero on one side or the
1036 // other, turn this into an *inclusive* or.
1037 // e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
1038 if ((DemandedMask & ~RHSKnownZero & ~LHSKnownZero) == 0) {
1040 BinaryOperator::CreateOr(I->getOperand(0), I->getOperand(1),
1042 return InsertNewInstBefore(Or, *I);
1045 // If all of the demanded bits on one side are known, and all of the set
1046 // bits on that side are also known to be set on the other side, turn this
1047 // into an AND, as we know the bits will be cleared.
1048 // e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
1049 if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask) {
1051 if ((RHSKnownOne & LHSKnownOne) == RHSKnownOne) {
1052 Constant *AndC = Constant::getIntegerValue(VTy,
1053 ~RHSKnownOne & DemandedMask);
1055 BinaryOperator::CreateAnd(I->getOperand(0), AndC, "tmp");
1056 return InsertNewInstBefore(And, *I);
1060 // If the RHS is a constant, see if we can simplify it.
1061 // FIXME: for XOR, we prefer to force bits to 1 if they will make a -1.
1062 if (ShrinkDemandedConstant(I, 1, DemandedMask))
1065 // If our LHS is an 'and' and if it has one use, and if any of the bits we
1066 // are flipping are known to be set, then the xor is just resetting those
1067 // bits to zero. We can just knock out bits from the 'and' and the 'xor',
1068 // simplifying both of them.
1069 if (Instruction *LHSInst = dyn_cast<Instruction>(I->getOperand(0)))
1070 if (LHSInst->getOpcode() == Instruction::And && LHSInst->hasOneUse() &&
1071 isa<ConstantInt>(I->getOperand(1)) &&
1072 isa<ConstantInt>(LHSInst->getOperand(1)) &&
1073 (LHSKnownOne & RHSKnownOne & DemandedMask) != 0) {
1074 ConstantInt *AndRHS = cast<ConstantInt>(LHSInst->getOperand(1));
1075 ConstantInt *XorRHS = cast<ConstantInt>(I->getOperand(1));
1076 APInt NewMask = ~(LHSKnownOne & RHSKnownOne & DemandedMask);
1079 ConstantInt::get(I->getType(), NewMask & AndRHS->getValue());
1080 Instruction *NewAnd =
1081 BinaryOperator::CreateAnd(I->getOperand(0), AndC, "tmp");
1082 InsertNewInstBefore(NewAnd, *I);
1085 ConstantInt::get(I->getType(), NewMask & XorRHS->getValue());
1086 Instruction *NewXor =
1087 BinaryOperator::CreateXor(NewAnd, XorC, "tmp");
1088 return InsertNewInstBefore(NewXor, *I);
1092 RHSKnownZero = KnownZeroOut;
1093 RHSKnownOne = KnownOneOut;
1096 case Instruction::Select:
1097 if (SimplifyDemandedBits(I->getOperandUse(2), DemandedMask,
1098 RHSKnownZero, RHSKnownOne, Depth+1) ||
1099 SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
1100 LHSKnownZero, LHSKnownOne, Depth+1))
1102 assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
1103 assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
1105 // If the operands are constants, see if we can simplify them.
1106 if (ShrinkDemandedConstant(I, 1, DemandedMask) ||
1107 ShrinkDemandedConstant(I, 2, DemandedMask))
1110 // Only known if known in both the LHS and RHS.
1111 RHSKnownOne &= LHSKnownOne;
1112 RHSKnownZero &= LHSKnownZero;
1114 case Instruction::Trunc: {
1115 unsigned truncBf = I->getOperand(0)->getType()->getScalarSizeInBits();
1116 DemandedMask.zext(truncBf);
1117 RHSKnownZero.zext(truncBf);
1118 RHSKnownOne.zext(truncBf);
1119 if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
1120 RHSKnownZero, RHSKnownOne, Depth+1))
1122 DemandedMask.trunc(BitWidth);
1123 RHSKnownZero.trunc(BitWidth);
1124 RHSKnownOne.trunc(BitWidth);
1125 assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
1128 case Instruction::BitCast:
1129 if (!I->getOperand(0)->getType()->isIntOrIntVector())
1130 return false; // vector->int or fp->int?
1132 if (const VectorType *DstVTy = dyn_cast<VectorType>(I->getType())) {
1133 if (const VectorType *SrcVTy =
1134 dyn_cast<VectorType>(I->getOperand(0)->getType())) {
1135 if (DstVTy->getNumElements() != SrcVTy->getNumElements())
1136 // Don't touch a bitcast between vectors of different element counts.
1139 // Don't touch a scalar-to-vector bitcast.
1141 } else if (isa<VectorType>(I->getOperand(0)->getType()))
1142 // Don't touch a vector-to-scalar bitcast.
1145 if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
1146 RHSKnownZero, RHSKnownOne, Depth+1))
1148 assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
1150 case Instruction::ZExt: {
1151 // Compute the bits in the result that are not present in the input.
1152 unsigned SrcBitWidth =I->getOperand(0)->getType()->getScalarSizeInBits();
1154 DemandedMask.trunc(SrcBitWidth);
1155 RHSKnownZero.trunc(SrcBitWidth);
1156 RHSKnownOne.trunc(SrcBitWidth);
1157 if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
1158 RHSKnownZero, RHSKnownOne, Depth+1))
1160 DemandedMask.zext(BitWidth);
1161 RHSKnownZero.zext(BitWidth);
1162 RHSKnownOne.zext(BitWidth);
1163 assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
1164 // The top bits are known to be zero.
1165 RHSKnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
1168 case Instruction::SExt: {
1169 // Compute the bits in the result that are not present in the input.
1170 unsigned SrcBitWidth =I->getOperand(0)->getType()->getScalarSizeInBits();
1172 APInt InputDemandedBits = DemandedMask &
1173 APInt::getLowBitsSet(BitWidth, SrcBitWidth);
1175 APInt NewBits(APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth));
1176 // If any of the sign extended bits are demanded, we know that the sign
1178 if ((NewBits & DemandedMask) != 0)
1179 InputDemandedBits.set(SrcBitWidth-1);
1181 InputDemandedBits.trunc(SrcBitWidth);
1182 RHSKnownZero.trunc(SrcBitWidth);
1183 RHSKnownOne.trunc(SrcBitWidth);
1184 if (SimplifyDemandedBits(I->getOperandUse(0), InputDemandedBits,
1185 RHSKnownZero, RHSKnownOne, Depth+1))
1187 InputDemandedBits.zext(BitWidth);
1188 RHSKnownZero.zext(BitWidth);
1189 RHSKnownOne.zext(BitWidth);
1190 assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
1192 // If the sign bit of the input is known set or clear, then we know the
1193 // top bits of the result.
1195 // If the input sign bit is known zero, or if the NewBits are not demanded
1196 // convert this into a zero extension.
1197 if (RHSKnownZero[SrcBitWidth-1] || (NewBits & ~DemandedMask) == NewBits) {
1198 // Convert to ZExt cast
1199 CastInst *NewCast = new ZExtInst(I->getOperand(0), VTy, I->getName());
1200 return InsertNewInstBefore(NewCast, *I);
1201 } else if (RHSKnownOne[SrcBitWidth-1]) { // Input sign bit known set
1202 RHSKnownOne |= NewBits;
1206 case Instruction::Add: {
1207 // Figure out what the input bits are. If the top bits of the and result
1208 // are not demanded, then the add doesn't demand them from its input
1210 unsigned NLZ = DemandedMask.countLeadingZeros();
1212 // If there is a constant on the RHS, there are a variety of xformations
1214 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
1215 // If null, this should be simplified elsewhere. Some of the xforms here
1216 // won't work if the RHS is zero.
1220 // If the top bit of the output is demanded, demand everything from the
1221 // input. Otherwise, we demand all the input bits except NLZ top bits.
1222 APInt InDemandedBits(APInt::getLowBitsSet(BitWidth, BitWidth - NLZ));
1224 // Find information about known zero/one bits in the input.
1225 if (SimplifyDemandedBits(I->getOperandUse(0), InDemandedBits,
1226 LHSKnownZero, LHSKnownOne, Depth+1))
1229 // If the RHS of the add has bits set that can't affect the input, reduce
1231 if (ShrinkDemandedConstant(I, 1, InDemandedBits))
1234 // Avoid excess work.
1235 if (LHSKnownZero == 0 && LHSKnownOne == 0)
1238 // Turn it into OR if input bits are zero.
1239 if ((LHSKnownZero & RHS->getValue()) == RHS->getValue()) {
1241 BinaryOperator::CreateOr(I->getOperand(0), I->getOperand(1),
1243 return InsertNewInstBefore(Or, *I);
1246 // We can say something about the output known-zero and known-one bits,
1247 // depending on potential carries from the input constant and the
1248 // unknowns. For example if the LHS is known to have at most the 0x0F0F0
1249 // bits set and the RHS constant is 0x01001, then we know we have a known
1250 // one mask of 0x00001 and a known zero mask of 0xE0F0E.
1252 // To compute this, we first compute the potential carry bits. These are
1253 // the bits which may be modified. I'm not aware of a better way to do
1255 const APInt &RHSVal = RHS->getValue();
1256 APInt CarryBits((~LHSKnownZero + RHSVal) ^ (~LHSKnownZero ^ RHSVal));
1258 // Now that we know which bits have carries, compute the known-1/0 sets.
1260 // Bits are known one if they are known zero in one operand and one in the
1261 // other, and there is no input carry.
1262 RHSKnownOne = ((LHSKnownZero & RHSVal) |
1263 (LHSKnownOne & ~RHSVal)) & ~CarryBits;
1265 // Bits are known zero if they are known zero in both operands and there
1266 // is no input carry.
1267 RHSKnownZero = LHSKnownZero & ~RHSVal & ~CarryBits;
1269 // If the high-bits of this ADD are not demanded, then it does not demand
1270 // the high bits of its LHS or RHS.
1271 if (DemandedMask[BitWidth-1] == 0) {
1272 // Right fill the mask of bits for this ADD to demand the most
1273 // significant bit and all those below it.
1274 APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ));
1275 if (SimplifyDemandedBits(I->getOperandUse(0), DemandedFromOps,
1276 LHSKnownZero, LHSKnownOne, Depth+1) ||
1277 SimplifyDemandedBits(I->getOperandUse(1), DemandedFromOps,
1278 LHSKnownZero, LHSKnownOne, Depth+1))
1284 case Instruction::Sub:
1285 // If the high-bits of this SUB are not demanded, then it does not demand
1286 // the high bits of its LHS or RHS.
1287 if (DemandedMask[BitWidth-1] == 0) {
1288 // Right fill the mask of bits for this SUB to demand the most
1289 // significant bit and all those below it.
1290 uint32_t NLZ = DemandedMask.countLeadingZeros();
1291 APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ));
1292 if (SimplifyDemandedBits(I->getOperandUse(0), DemandedFromOps,
1293 LHSKnownZero, LHSKnownOne, Depth+1) ||
1294 SimplifyDemandedBits(I->getOperandUse(1), DemandedFromOps,
1295 LHSKnownZero, LHSKnownOne, Depth+1))
1298 // Otherwise just hand the sub off to ComputeMaskedBits to fill in
1299 // the known zeros and ones.
1300 ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
1302 case Instruction::Shl:
1303 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
1304 uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
1305 APInt DemandedMaskIn(DemandedMask.lshr(ShiftAmt));
1306 if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn,
1307 RHSKnownZero, RHSKnownOne, Depth+1))
1309 assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
1310 RHSKnownZero <<= ShiftAmt;
1311 RHSKnownOne <<= ShiftAmt;
1312 // low bits known zero.
1314 RHSKnownZero |= APInt::getLowBitsSet(BitWidth, ShiftAmt);
1317 case Instruction::LShr:
1318 // For a logical shift right
1319 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
1320 uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
1322 // Unsigned shift right.
1323 APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
1324 if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn,
1325 RHSKnownZero, RHSKnownOne, Depth+1))
1327 assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
1328 RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
1329 RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt);
1331 // Compute the new bits that are at the top now.
1332 APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
1333 RHSKnownZero |= HighBits; // high bits known zero.
1337 case Instruction::AShr:
1338 // If this is an arithmetic shift right and only the low-bit is set, we can
1339 // always convert this into a logical shr, even if the shift amount is
1340 // variable. The low bit of the shift cannot be an input sign bit unless
1341 // the shift amount is >= the size of the datatype, which is undefined.
1342 if (DemandedMask == 1) {
1343 // Perform the logical shift right.
1344 Instruction *NewVal = BinaryOperator::CreateLShr(
1345 I->getOperand(0), I->getOperand(1), I->getName());
1346 return InsertNewInstBefore(NewVal, *I);
1349 // If the sign bit is the only bit demanded by this ashr, then there is no
1350 // need to do it, the shift doesn't change the high bit.
1351 if (DemandedMask.isSignBit())
1352 return I->getOperand(0);
1354 if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
1355 uint32_t ShiftAmt = SA->getLimitedValue(BitWidth);
1357 // Signed shift right.
1358 APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
1359 // If any of the "high bits" are demanded, we should set the sign bit as
1361 if (DemandedMask.countLeadingZeros() <= ShiftAmt)
1362 DemandedMaskIn.set(BitWidth-1);
1363 if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn,
1364 RHSKnownZero, RHSKnownOne, Depth+1))
1366 assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
1367 // Compute the new bits that are at the top now.
1368 APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
1369 RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
1370 RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt);
1372 // Handle the sign bits.
1373 APInt SignBit(APInt::getSignBit(BitWidth));
1374 // Adjust to where it is now in the mask.
1375 SignBit = APIntOps::lshr(SignBit, ShiftAmt);
1377 // If the input sign bit is known to be zero, or if none of the top bits
1378 // are demanded, turn this into an unsigned shift right.
1379 if (BitWidth <= ShiftAmt || RHSKnownZero[BitWidth-ShiftAmt-1] ||
1380 (HighBits & ~DemandedMask) == HighBits) {
1381 // Perform the logical shift right.
1382 Instruction *NewVal = BinaryOperator::CreateLShr(
1383 I->getOperand(0), SA, I->getName());
1384 return InsertNewInstBefore(NewVal, *I);
1385 } else if ((RHSKnownOne & SignBit) != 0) { // New bits are known one.
1386 RHSKnownOne |= HighBits;
1390 case Instruction::SRem:
1391 if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
1392 APInt RA = Rem->getValue().abs();
1393 if (RA.isPowerOf2()) {
1394 if (DemandedMask.ult(RA)) // srem won't affect demanded bits
1395 return I->getOperand(0);
1397 APInt LowBits = RA - 1;
1398 APInt Mask2 = LowBits | APInt::getSignBit(BitWidth);
1399 if (SimplifyDemandedBits(I->getOperandUse(0), Mask2,
1400 LHSKnownZero, LHSKnownOne, Depth+1))
1403 if (LHSKnownZero[BitWidth-1] || ((LHSKnownZero & LowBits) == LowBits))
1404 LHSKnownZero |= ~LowBits;
1406 KnownZero |= LHSKnownZero & DemandedMask;
1408 assert(!(KnownZero & KnownOne) && "Bits known to be one AND zero?");
1412 case Instruction::URem: {
1413 APInt KnownZero2(BitWidth, 0), KnownOne2(BitWidth, 0);
1414 APInt AllOnes = APInt::getAllOnesValue(BitWidth);
1415 if (SimplifyDemandedBits(I->getOperandUse(0), AllOnes,
1416 KnownZero2, KnownOne2, Depth+1) ||
1417 SimplifyDemandedBits(I->getOperandUse(1), AllOnes,
1418 KnownZero2, KnownOne2, Depth+1))
1421 unsigned Leaders = KnownZero2.countLeadingOnes();
1422 Leaders = std::max(Leaders,
1423 KnownZero2.countLeadingOnes());
1424 KnownZero = APInt::getHighBitsSet(BitWidth, Leaders) & DemandedMask;
1427 case Instruction::Call:
1428 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
1429 switch (II->getIntrinsicID()) {
1431 case Intrinsic::bswap: {
1432 // If the only bits demanded come from one byte of the bswap result,
1433 // just shift the input byte into position to eliminate the bswap.
1434 unsigned NLZ = DemandedMask.countLeadingZeros();
1435 unsigned NTZ = DemandedMask.countTrailingZeros();
1437 // Round NTZ down to the next byte. If we have 11 trailing zeros, then
1438 // we need all the bits down to bit 8. Likewise, round NLZ. If we
1439 // have 14 leading zeros, round to 8.
1442 // If we need exactly one byte, we can do this transformation.
1443 if (BitWidth-NLZ-NTZ == 8) {
1444 unsigned ResultBit = NTZ;
1445 unsigned InputBit = BitWidth-NTZ-8;
1447 // Replace this with either a left or right shift to get the byte into
1449 Instruction *NewVal;
1450 if (InputBit > ResultBit)
1451 NewVal = BinaryOperator::CreateLShr(I->getOperand(1),
1452 ConstantInt::get(I->getType(), InputBit-ResultBit));
1454 NewVal = BinaryOperator::CreateShl(I->getOperand(1),
1455 ConstantInt::get(I->getType(), ResultBit-InputBit));
1456 NewVal->takeName(I);
1457 return InsertNewInstBefore(NewVal, *I);
1460 // TODO: Could compute known zero/one bits based on the input.
1465 ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
1469 // If the client is only demanding bits that we know, return the known
1471 if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask)
1472 return Constant::getIntegerValue(VTy, RHSKnownOne);
1477 /// SimplifyDemandedVectorElts - The specified value produces a vector with
1478 /// any number of elements. DemandedElts contains the set of elements that are
1479 /// actually used by the caller. This method analyzes which elements of the
1480 /// operand are undef and returns that information in UndefElts.
1482 /// If the information about demanded elements can be used to simplify the
1483 /// operation, the operation is simplified, then the resultant value is
1484 /// returned. This returns null if no change was made.
1485 Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
1488 unsigned VWidth = cast<VectorType>(V->getType())->getNumElements();
1489 APInt EltMask(APInt::getAllOnesValue(VWidth));
1490 assert((DemandedElts & ~EltMask) == 0 && "Invalid DemandedElts!");
1492 if (isa<UndefValue>(V)) {
1493 // If the entire vector is undefined, just return this info.
1494 UndefElts = EltMask;
1496 } else if (DemandedElts == 0) { // If nothing is demanded, provide undef.
1497 UndefElts = EltMask;
1498 return UndefValue::get(V->getType());
1502 if (ConstantVector *CP = dyn_cast<ConstantVector>(V)) {
1503 const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
1504 Constant *Undef = UndefValue::get(EltTy);
1506 std::vector<Constant*> Elts;
1507 for (unsigned i = 0; i != VWidth; ++i)
1508 if (!DemandedElts[i]) { // If not demanded, set to undef.
1509 Elts.push_back(Undef);
1511 } else if (isa<UndefValue>(CP->getOperand(i))) { // Already undef.
1512 Elts.push_back(Undef);
1514 } else { // Otherwise, defined.
1515 Elts.push_back(CP->getOperand(i));
1518 // If we changed the constant, return it.
1519 Constant *NewCP = ConstantVector::get(Elts);
1520 return NewCP != CP ? NewCP : 0;
1521 } else if (isa<ConstantAggregateZero>(V)) {
1522 // Simplify the CAZ to a ConstantVector where the non-demanded elements are
1525 // Check if this is identity. If so, return 0 since we are not simplifying
1527 if (DemandedElts == ((1ULL << VWidth) -1))
1530 const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
1531 Constant *Zero = Constant::getNullValue(EltTy);
1532 Constant *Undef = UndefValue::get(EltTy);
1533 std::vector<Constant*> Elts;
1534 for (unsigned i = 0; i != VWidth; ++i) {
1535 Constant *Elt = DemandedElts[i] ? Zero : Undef;
1536 Elts.push_back(Elt);
1538 UndefElts = DemandedElts ^ EltMask;
1539 return ConstantVector::get(Elts);
1542 // Limit search depth.
1546 // If multiple users are using the root value, procede with
1547 // simplification conservatively assuming that all elements
1549 if (!V->hasOneUse()) {
1550 // Quit if we find multiple users of a non-root value though.
1551 // They'll be handled when it's their turn to be visited by
1552 // the main instcombine process.
1554 // TODO: Just compute the UndefElts information recursively.
1557 // Conservatively assume that all elements are needed.
1558 DemandedElts = EltMask;
1561 Instruction *I = dyn_cast<Instruction>(V);
1562 if (!I) return 0; // Only analyze instructions.
1564 bool MadeChange = false;
1565 APInt UndefElts2(VWidth, 0);
1567 switch (I->getOpcode()) {
1570 case Instruction::InsertElement: {
1571 // If this is a variable index, we don't know which element it overwrites.
1572 // demand exactly the same input as we produce.
1573 ConstantInt *Idx = dyn_cast<ConstantInt>(I->getOperand(2));
1575 // Note that we can't propagate undef elt info, because we don't know
1576 // which elt is getting updated.
1577 TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
1578 UndefElts2, Depth+1);
1579 if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
1583 // If this is inserting an element that isn't demanded, remove this
1585 unsigned IdxNo = Idx->getZExtValue();
1586 if (IdxNo >= VWidth || !DemandedElts[IdxNo]) {
1588 return I->getOperand(0);
1591 // Otherwise, the element inserted overwrites whatever was there, so the
1592 // input demanded set is simpler than the output set.
1593 APInt DemandedElts2 = DemandedElts;
1594 DemandedElts2.clear(IdxNo);
1595 TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts2,
1596 UndefElts, Depth+1);
1597 if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
1599 // The inserted element is defined.
1600 UndefElts.clear(IdxNo);
1603 case Instruction::ShuffleVector: {
1604 ShuffleVectorInst *Shuffle = cast<ShuffleVectorInst>(I);
1605 uint64_t LHSVWidth =
1606 cast<VectorType>(Shuffle->getOperand(0)->getType())->getNumElements();
1607 APInt LeftDemanded(LHSVWidth, 0), RightDemanded(LHSVWidth, 0);
1608 for (unsigned i = 0; i < VWidth; i++) {
1609 if (DemandedElts[i]) {
1610 unsigned MaskVal = Shuffle->getMaskValue(i);
1611 if (MaskVal != -1u) {
1612 assert(MaskVal < LHSVWidth * 2 &&
1613 "shufflevector mask index out of range!");
1614 if (MaskVal < LHSVWidth)
1615 LeftDemanded.set(MaskVal);
1617 RightDemanded.set(MaskVal - LHSVWidth);
1622 APInt UndefElts4(LHSVWidth, 0);
1623 TmpV = SimplifyDemandedVectorElts(I->getOperand(0), LeftDemanded,
1624 UndefElts4, Depth+1);
1625 if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
1627 APInt UndefElts3(LHSVWidth, 0);
1628 TmpV = SimplifyDemandedVectorElts(I->getOperand(1), RightDemanded,
1629 UndefElts3, Depth+1);
1630 if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; }
1632 bool NewUndefElts = false;
1633 for (unsigned i = 0; i < VWidth; i++) {
1634 unsigned MaskVal = Shuffle->getMaskValue(i);
1635 if (MaskVal == -1u) {
1637 } else if (MaskVal < LHSVWidth) {
1638 if (UndefElts4[MaskVal]) {
1639 NewUndefElts = true;
1643 if (UndefElts3[MaskVal - LHSVWidth]) {
1644 NewUndefElts = true;
1651 // Add additional discovered undefs.
1652 std::vector<Constant*> Elts;
1653 for (unsigned i = 0; i < VWidth; ++i) {
1655 Elts.push_back(UndefValue::get(Type::getInt32Ty(*Context)));
1657 Elts.push_back(ConstantInt::get(Type::getInt32Ty(*Context),
1658 Shuffle->getMaskValue(i)));
1660 I->setOperand(2, ConstantVector::get(Elts));
1665 case Instruction::BitCast: {
1666 // Vector->vector casts only.
1667 const VectorType *VTy = dyn_cast<VectorType>(I->getOperand(0)->getType());
1669 unsigned InVWidth = VTy->getNumElements();
1670 APInt InputDemandedElts(InVWidth, 0);
1673 if (VWidth == InVWidth) {
1674 // If we are converting from <4 x i32> -> <4 x f32>, we demand the same
1675 // elements as are demanded of us.
1677 InputDemandedElts = DemandedElts;
1678 } else if (VWidth > InVWidth) {
1682 // If there are more elements in the result than there are in the source,
1683 // then an input element is live if any of the corresponding output
1684 // elements are live.
1685 Ratio = VWidth/InVWidth;
1686 for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx) {
1687 if (DemandedElts[OutIdx])
1688 InputDemandedElts.set(OutIdx/Ratio);
1694 // If there are more elements in the source than there are in the result,
1695 // then an input element is live if the corresponding output element is
1697 Ratio = InVWidth/VWidth;
1698 for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
1699 if (DemandedElts[InIdx/Ratio])
1700 InputDemandedElts.set(InIdx);
1703 // div/rem demand all inputs, because they don't want divide by zero.
1704 TmpV = SimplifyDemandedVectorElts(I->getOperand(0), InputDemandedElts,
1705 UndefElts2, Depth+1);
1707 I->setOperand(0, TmpV);
1711 UndefElts = UndefElts2;
1712 if (VWidth > InVWidth) {
1713 llvm_unreachable("Unimp");
1714 // If there are more elements in the result than there are in the source,
1715 // then an output element is undef if the corresponding input element is
1717 for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx)
1718 if (UndefElts2[OutIdx/Ratio])
1719 UndefElts.set(OutIdx);
1720 } else if (VWidth < InVWidth) {
1721 llvm_unreachable("Unimp");
1722 // If there are more elements in the source than there are in the result,
1723 // then a result element is undef if all of the corresponding input
1724 // elements are undef.
1725 UndefElts = ~0ULL >> (64-VWidth); // Start out all undef.
1726 for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
1727 if (!UndefElts2[InIdx]) // Not undef?
1728 UndefElts.clear(InIdx/Ratio); // Clear undef bit.
1732 case Instruction::And:
1733 case Instruction::Or:
1734 case Instruction::Xor:
1735 case Instruction::Add:
1736 case Instruction::Sub:
1737 case Instruction::Mul:
1738 // div/rem demand all inputs, because they don't want divide by zero.
1739 TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
1740 UndefElts, Depth+1);
1741 if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
1742 TmpV = SimplifyDemandedVectorElts(I->getOperand(1), DemandedElts,
1743 UndefElts2, Depth+1);
1744 if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; }
1746 // Output elements are undefined if both are undefined. Consider things
1747 // like undef&0. The result is known zero, not undef.
1748 UndefElts &= UndefElts2;
1751 case Instruction::Call: {
1752 IntrinsicInst *II = dyn_cast<IntrinsicInst>(I);
1754 switch (II->getIntrinsicID()) {
1757 // Binary vector operations that work column-wise. A dest element is a
1758 // function of the corresponding input elements from the two inputs.
1759 case Intrinsic::x86_sse_sub_ss:
1760 case Intrinsic::x86_sse_mul_ss:
1761 case Intrinsic::x86_sse_min_ss:
1762 case Intrinsic::x86_sse_max_ss:
1763 case Intrinsic::x86_sse2_sub_sd:
1764 case Intrinsic::x86_sse2_mul_sd:
1765 case Intrinsic::x86_sse2_min_sd:
1766 case Intrinsic::x86_sse2_max_sd:
1767 TmpV = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts,
1768 UndefElts, Depth+1);
1769 if (TmpV) { II->setOperand(1, TmpV); MadeChange = true; }
1770 TmpV = SimplifyDemandedVectorElts(II->getOperand(2), DemandedElts,
1771 UndefElts2, Depth+1);
1772 if (TmpV) { II->setOperand(2, TmpV); MadeChange = true; }
1774 // If only the low elt is demanded and this is a scalarizable intrinsic,
1775 // scalarize it now.
1776 if (DemandedElts == 1) {
1777 switch (II->getIntrinsicID()) {
1779 case Intrinsic::x86_sse_sub_ss:
1780 case Intrinsic::x86_sse_mul_ss:
1781 case Intrinsic::x86_sse2_sub_sd:
1782 case Intrinsic::x86_sse2_mul_sd:
1783 // TODO: Lower MIN/MAX/ABS/etc
1784 Value *LHS = II->getOperand(1);
1785 Value *RHS = II->getOperand(2);
1786 // Extract the element as scalars.
1787 LHS = InsertNewInstBefore(ExtractElementInst::Create(LHS,
1788 ConstantInt::get(Type::getInt32Ty(*Context), 0U, false), "tmp"), *II);
1789 RHS = InsertNewInstBefore(ExtractElementInst::Create(RHS,
1790 ConstantInt::get(Type::getInt32Ty(*Context), 0U, false), "tmp"), *II);
1792 switch (II->getIntrinsicID()) {
1793 default: llvm_unreachable("Case stmts out of sync!");
1794 case Intrinsic::x86_sse_sub_ss:
1795 case Intrinsic::x86_sse2_sub_sd:
1796 TmpV = InsertNewInstBefore(BinaryOperator::CreateFSub(LHS, RHS,
1797 II->getName()), *II);
1799 case Intrinsic::x86_sse_mul_ss:
1800 case Intrinsic::x86_sse2_mul_sd:
1801 TmpV = InsertNewInstBefore(BinaryOperator::CreateFMul(LHS, RHS,
1802 II->getName()), *II);
1807 InsertElementInst::Create(
1808 UndefValue::get(II->getType()), TmpV,
1809 ConstantInt::get(Type::getInt32Ty(*Context), 0U, false), II->getName());
1810 InsertNewInstBefore(New, *II);
1815 // Output elements are undefined if both are undefined. Consider things
1816 // like undef&0. The result is known zero, not undef.
1817 UndefElts &= UndefElts2;
1823 return MadeChange ? I : 0;
1827 /// AssociativeOpt - Perform an optimization on an associative operator. This
1828 /// function is designed to check a chain of associative operators for a
1829 /// potential to apply a certain optimization. Since the optimization may be
1830 /// applicable if the expression was reassociated, this checks the chain, then
1831 /// reassociates the expression as necessary to expose the optimization
1832 /// opportunity. This makes use of a special Functor, which must define
1833 /// 'shouldApply' and 'apply' methods.
1835 template<typename Functor>
1836 static Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
1837 unsigned Opcode = Root.getOpcode();
1838 Value *LHS = Root.getOperand(0);
1840 // Quick check, see if the immediate LHS matches...
1841 if (F.shouldApply(LHS))
1842 return F.apply(Root);
1844 // Otherwise, if the LHS is not of the same opcode as the root, return.
1845 Instruction *LHSI = dyn_cast<Instruction>(LHS);
1846 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
1847 // Should we apply this transform to the RHS?
1848 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
1850 // If not to the RHS, check to see if we should apply to the LHS...
1851 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
1852 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
1856 // If the functor wants to apply the optimization to the RHS of LHSI,
1857 // reassociate the expression from ((? op A) op B) to (? op (A op B))
1859 // Now all of the instructions are in the current basic block, go ahead
1860 // and perform the reassociation.
1861 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
1863 // First move the selected RHS to the LHS of the root...
1864 Root.setOperand(0, LHSI->getOperand(1));
1866 // Make what used to be the LHS of the root be the user of the root...
1867 Value *ExtraOperand = TmpLHSI->getOperand(1);
1868 if (&Root == TmpLHSI) {
1869 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
1872 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
1873 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
1874 BasicBlock::iterator ARI = &Root; ++ARI;
1875 TmpLHSI->moveBefore(ARI); // Move TmpLHSI to after Root
1878 // Now propagate the ExtraOperand down the chain of instructions until we
1880 while (TmpLHSI != LHSI) {
1881 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
1882 // Move the instruction to immediately before the chain we are
1883 // constructing to avoid breaking dominance properties.
1884 NextLHSI->moveBefore(ARI);
1887 Value *NextOp = NextLHSI->getOperand(1);
1888 NextLHSI->setOperand(1, ExtraOperand);
1890 ExtraOperand = NextOp;
1893 // Now that the instructions are reassociated, have the functor perform
1894 // the transformation...
1895 return F.apply(Root);
1898 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
1905 // AddRHS - Implements: X + X --> X << 1
1908 explicit AddRHS(Value *rhs) : RHS(rhs) {}
1909 bool shouldApply(Value *LHS) const { return LHS == RHS; }
1910 Instruction *apply(BinaryOperator &Add) const {
1911 return BinaryOperator::CreateShl(Add.getOperand(0),
1912 ConstantInt::get(Add.getType(), 1));
1916 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
1918 struct AddMaskingAnd {
1920 explicit AddMaskingAnd(Constant *c) : C2(c) {}
1921 bool shouldApply(Value *LHS) const {
1923 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
1924 ConstantExpr::getAnd(C1, C2)->isNullValue();
1926 Instruction *apply(BinaryOperator &Add) const {
1927 return BinaryOperator::CreateOr(Add.getOperand(0), Add.getOperand(1));
1933 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
1935 if (CastInst *CI = dyn_cast<CastInst>(&I))
1936 return IC->Builder->CreateCast(CI->getOpcode(), SO, I.getType());
1938 // Figure out if the constant is the left or the right argument.
1939 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
1940 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
1942 if (Constant *SOC = dyn_cast<Constant>(SO)) {
1944 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
1945 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
1948 Value *Op0 = SO, *Op1 = ConstOperand;
1950 std::swap(Op0, Op1);
1952 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
1953 return IC->Builder->CreateBinOp(BO->getOpcode(), Op0, Op1,
1954 SO->getName()+".op");
1955 if (ICmpInst *CI = dyn_cast<ICmpInst>(&I))
1956 return IC->Builder->CreateICmp(CI->getPredicate(), Op0, Op1,
1957 SO->getName()+".cmp");
1958 if (FCmpInst *CI = dyn_cast<FCmpInst>(&I))
1959 return IC->Builder->CreateICmp(CI->getPredicate(), Op0, Op1,
1960 SO->getName()+".cmp");
1961 llvm_unreachable("Unknown binary instruction type!");
1964 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
1965 // constant as the other operand, try to fold the binary operator into the
1966 // select arguments. This also works for Cast instructions, which obviously do
1967 // not have a second operand.
1968 static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
1970 // Don't modify shared select instructions
1971 if (!SI->hasOneUse()) return 0;
1972 Value *TV = SI->getOperand(1);
1973 Value *FV = SI->getOperand(2);
1975 if (isa<Constant>(TV) || isa<Constant>(FV)) {
1976 // Bool selects with constant operands can be folded to logical ops.
1977 if (SI->getType() == Type::getInt1Ty(*IC->getContext())) return 0;
1979 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
1980 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
1982 return SelectInst::Create(SI->getCondition(), SelectTrueVal,
1989 /// FoldOpIntoPhi - Given a binary operator, cast instruction, or select which
1990 /// has a PHI node as operand #0, see if we can fold the instruction into the
1991 /// PHI (which is only possible if all operands to the PHI are constants).
1993 /// If AllowAggressive is true, FoldOpIntoPhi will allow certain transforms
1994 /// that would normally be unprofitable because they strongly encourage jump
1996 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I,
1997 bool AllowAggressive) {
1998 AllowAggressive = false;
1999 PHINode *PN = cast<PHINode>(I.getOperand(0));
2000 unsigned NumPHIValues = PN->getNumIncomingValues();
2001 if (NumPHIValues == 0 ||
2002 // We normally only transform phis with a single use, unless we're trying
2003 // hard to make jump threading happen.
2004 (!PN->hasOneUse() && !AllowAggressive))
2008 // Check to see if all of the operands of the PHI are simple constants
2009 // (constantint/constantfp/undef). If there is one non-constant value,
2010 // remember the BB it is in. If there is more than one or if *it* is a PHI,
2011 // bail out. We don't do arbitrary constant expressions here because moving
2012 // their computation can be expensive without a cost model.
2013 BasicBlock *NonConstBB = 0;
2014 for (unsigned i = 0; i != NumPHIValues; ++i)
2015 if (!isa<Constant>(PN->getIncomingValue(i)) ||
2016 isa<ConstantExpr>(PN->getIncomingValue(i))) {
2017 if (NonConstBB) return 0; // More than one non-const value.
2018 if (isa<PHINode>(PN->getIncomingValue(i))) return 0; // Itself a phi.
2019 NonConstBB = PN->getIncomingBlock(i);
2021 // If the incoming non-constant value is in I's block, we have an infinite
2023 if (NonConstBB == I.getParent())
2027 // If there is exactly one non-constant value, we can insert a copy of the
2028 // operation in that block. However, if this is a critical edge, we would be
2029 // inserting the computation one some other paths (e.g. inside a loop). Only
2030 // do this if the pred block is unconditionally branching into the phi block.
2031 if (NonConstBB != 0 && !AllowAggressive) {
2032 BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
2033 if (!BI || !BI->isUnconditional()) return 0;
2036 // Okay, we can do the transformation: create the new PHI node.
2037 PHINode *NewPN = PHINode::Create(I.getType(), "");
2038 NewPN->reserveOperandSpace(PN->getNumOperands()/2);
2039 InsertNewInstBefore(NewPN, *PN);
2040 NewPN->takeName(PN);
2042 // Next, add all of the operands to the PHI.
2043 if (SelectInst *SI = dyn_cast<SelectInst>(&I)) {
2044 // We only currently try to fold the condition of a select when it is a phi,
2045 // not the true/false values.
2046 Value *TrueV = SI->getTrueValue();
2047 Value *FalseV = SI->getFalseValue();
2048 BasicBlock *PhiTransBB = PN->getParent();
2049 for (unsigned i = 0; i != NumPHIValues; ++i) {
2050 BasicBlock *ThisBB = PN->getIncomingBlock(i);
2051 Value *TrueVInPred = TrueV->DoPHITranslation(PhiTransBB, ThisBB);
2052 Value *FalseVInPred = FalseV->DoPHITranslation(PhiTransBB, ThisBB);
2054 if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
2055 InV = InC->isNullValue() ? FalseVInPred : TrueVInPred;
2057 assert(PN->getIncomingBlock(i) == NonConstBB);
2058 InV = SelectInst::Create(PN->getIncomingValue(i), TrueVInPred,
2060 "phitmp", NonConstBB->getTerminator());
2061 Worklist.Add(cast<Instruction>(InV));
2063 NewPN->addIncoming(InV, ThisBB);
2065 } else if (I.getNumOperands() == 2) {
2066 Constant *C = cast<Constant>(I.getOperand(1));
2067 for (unsigned i = 0; i != NumPHIValues; ++i) {
2069 if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
2070 if (CmpInst *CI = dyn_cast<CmpInst>(&I))
2071 InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
2073 InV = ConstantExpr::get(I.getOpcode(), InC, C);
2075 assert(PN->getIncomingBlock(i) == NonConstBB);
2076 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
2077 InV = BinaryOperator::Create(BO->getOpcode(),
2078 PN->getIncomingValue(i), C, "phitmp",
2079 NonConstBB->getTerminator());
2080 else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
2081 InV = CmpInst::Create(CI->getOpcode(),
2083 PN->getIncomingValue(i), C, "phitmp",
2084 NonConstBB->getTerminator());
2086 llvm_unreachable("Unknown binop!");
2088 Worklist.Add(cast<Instruction>(InV));
2090 NewPN->addIncoming(InV, PN->getIncomingBlock(i));
2093 CastInst *CI = cast<CastInst>(&I);
2094 const Type *RetTy = CI->getType();
2095 for (unsigned i = 0; i != NumPHIValues; ++i) {
2097 if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
2098 InV = ConstantExpr::getCast(CI->getOpcode(), InC, RetTy);
2100 assert(PN->getIncomingBlock(i) == NonConstBB);
2101 InV = CastInst::Create(CI->getOpcode(), PN->getIncomingValue(i),
2102 I.getType(), "phitmp",
2103 NonConstBB->getTerminator());
2104 Worklist.Add(cast<Instruction>(InV));
2106 NewPN->addIncoming(InV, PN->getIncomingBlock(i));
2109 return ReplaceInstUsesWith(I, NewPN);
2113 /// WillNotOverflowSignedAdd - Return true if we can prove that:
2114 /// (sext (add LHS, RHS)) === (add (sext LHS), (sext RHS))
2115 /// This basically requires proving that the add in the original type would not
2116 /// overflow to change the sign bit or have a carry out.
2117 bool InstCombiner::WillNotOverflowSignedAdd(Value *LHS, Value *RHS) {
2118 // There are different heuristics we can use for this. Here are some simple
2121 // Add has the property that adding any two 2's complement numbers can only
2122 // have one carry bit which can change a sign. As such, if LHS and RHS each
2123 // have at least two sign bits, we know that the addition of the two values will
2124 // sign extend fine.
2125 if (ComputeNumSignBits(LHS) > 1 && ComputeNumSignBits(RHS) > 1)
2129 // If one of the operands only has one non-zero bit, and if the other operand
2130 // has a known-zero bit in a more significant place than it (not including the
2131 // sign bit) the ripple may go up to and fill the zero, but won't change the
2132 // sign. For example, (X & ~4) + 1.
2140 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
2141 bool Changed = SimplifyCommutative(I);
2142 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
2144 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
2145 // X + undef -> undef
2146 if (isa<UndefValue>(RHS))
2147 return ReplaceInstUsesWith(I, RHS);
2150 if (RHSC->isNullValue())
2151 return ReplaceInstUsesWith(I, LHS);
2153 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
2154 // X + (signbit) --> X ^ signbit
2155 const APInt& Val = CI->getValue();
2156 uint32_t BitWidth = Val.getBitWidth();
2157 if (Val == APInt::getSignBit(BitWidth))
2158 return BinaryOperator::CreateXor(LHS, RHS);
2160 // See if SimplifyDemandedBits can simplify this. This handles stuff like
2161 // (X & 254)+1 -> (X&254)|1
2162 if (SimplifyDemandedInstructionBits(I))
2165 // zext(bool) + C -> bool ? C + 1 : C
2166 if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS))
2167 if (ZI->getSrcTy() == Type::getInt1Ty(*Context))
2168 return SelectInst::Create(ZI->getOperand(0), AddOne(CI), CI);
2171 if (isa<PHINode>(LHS))
2172 if (Instruction *NV = FoldOpIntoPhi(I))
2175 ConstantInt *XorRHS = 0;
2177 if (isa<ConstantInt>(RHSC) &&
2178 match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
2179 uint32_t TySizeBits = I.getType()->getScalarSizeInBits();
2180 const APInt& RHSVal = cast<ConstantInt>(RHSC)->getValue();
2182 uint32_t Size = TySizeBits / 2;
2183 APInt C0080Val(APInt(TySizeBits, 1ULL).shl(Size - 1));
2184 APInt CFF80Val(-C0080Val);
2186 if (TySizeBits > Size) {
2187 // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
2188 // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
2189 if ((RHSVal == CFF80Val && XorRHS->getValue() == C0080Val) ||
2190 (RHSVal == C0080Val && XorRHS->getValue() == CFF80Val)) {
2191 // This is a sign extend if the top bits are known zero.
2192 if (!MaskedValueIsZero(XorLHS,
2193 APInt::getHighBitsSet(TySizeBits, TySizeBits - Size)))
2194 Size = 0; // Not a sign ext, but can't be any others either.
2199 C0080Val = APIntOps::lshr(C0080Val, Size);
2200 CFF80Val = APIntOps::ashr(CFF80Val, Size);
2201 } while (Size >= 1);
2203 // FIXME: This shouldn't be necessary. When the backends can handle types
2204 // with funny bit widths then this switch statement should be removed. It
2205 // is just here to get the size of the "middle" type back up to something
2206 // that the back ends can handle.
2207 const Type *MiddleType = 0;
2210 case 32: MiddleType = Type::getInt32Ty(*Context); break;
2211 case 16: MiddleType = Type::getInt16Ty(*Context); break;
2212 case 8: MiddleType = Type::getInt8Ty(*Context); break;
2215 Value *NewTrunc = Builder->CreateTrunc(XorLHS, MiddleType, "sext");
2216 return new SExtInst(NewTrunc, I.getType(), I.getName());
2221 if (I.getType() == Type::getInt1Ty(*Context))
2222 return BinaryOperator::CreateXor(LHS, RHS);
2225 if (I.getType()->isInteger()) {
2226 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS)))
2229 if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
2230 if (RHSI->getOpcode() == Instruction::Sub)
2231 if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
2232 return ReplaceInstUsesWith(I, RHSI->getOperand(0));
2234 if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
2235 if (LHSI->getOpcode() == Instruction::Sub)
2236 if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
2237 return ReplaceInstUsesWith(I, LHSI->getOperand(0));
2242 // -A + -B --> -(A + B)
2243 if (Value *LHSV = dyn_castNegVal(LHS)) {
2244 if (LHS->getType()->isIntOrIntVector()) {
2245 if (Value *RHSV = dyn_castNegVal(RHS)) {
2246 Value *NewAdd = Builder->CreateAdd(LHSV, RHSV, "sum");
2247 return BinaryOperator::CreateNeg(NewAdd);
2251 return BinaryOperator::CreateSub(RHS, LHSV);
2255 if (!isa<Constant>(RHS))
2256 if (Value *V = dyn_castNegVal(RHS))
2257 return BinaryOperator::CreateSub(LHS, V);
2261 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
2262 if (X == RHS) // X*C + X --> X * (C+1)
2263 return BinaryOperator::CreateMul(RHS, AddOne(C2));
2265 // X*C1 + X*C2 --> X * (C1+C2)
2267 if (X == dyn_castFoldableMul(RHS, C1))
2268 return BinaryOperator::CreateMul(X, ConstantExpr::getAdd(C1, C2));
2271 // X + X*C --> X * (C+1)
2272 if (dyn_castFoldableMul(RHS, C2) == LHS)
2273 return BinaryOperator::CreateMul(LHS, AddOne(C2));
2275 // X + ~X --> -1 since ~X = -X-1
2276 if (dyn_castNotVal(LHS) == RHS ||
2277 dyn_castNotVal(RHS) == LHS)
2278 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
2281 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
2282 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
2283 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2)))
2286 // A+B --> A|B iff A and B have no bits set in common.
2287 if (const IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
2288 APInt Mask = APInt::getAllOnesValue(IT->getBitWidth());
2289 APInt LHSKnownOne(IT->getBitWidth(), 0);
2290 APInt LHSKnownZero(IT->getBitWidth(), 0);
2291 ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne);
2292 if (LHSKnownZero != 0) {
2293 APInt RHSKnownOne(IT->getBitWidth(), 0);
2294 APInt RHSKnownZero(IT->getBitWidth(), 0);
2295 ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne);
2297 // No bits in common -> bitwise or.
2298 if ((LHSKnownZero|RHSKnownZero).isAllOnesValue())
2299 return BinaryOperator::CreateOr(LHS, RHS);
2303 // W*X + Y*Z --> W * (X+Z) iff W == Y
2304 if (I.getType()->isIntOrIntVector()) {
2305 Value *W, *X, *Y, *Z;
2306 if (match(LHS, m_Mul(m_Value(W), m_Value(X))) &&
2307 match(RHS, m_Mul(m_Value(Y), m_Value(Z)))) {
2311 } else if (Y == X) {
2313 } else if (X == Z) {
2320 Value *NewAdd = Builder->CreateAdd(X, Z, LHS->getName());
2321 return BinaryOperator::CreateMul(W, NewAdd);
2326 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
2328 if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X
2329 return BinaryOperator::CreateSub(SubOne(CRHS), X);
2331 // (X & FF00) + xx00 -> (X+xx00) & FF00
2332 if (LHS->hasOneUse() &&
2333 match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
2334 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
2335 if (Anded == CRHS) {
2336 // See if all bits from the first bit set in the Add RHS up are included
2337 // in the mask. First, get the rightmost bit.
2338 const APInt& AddRHSV = CRHS->getValue();
2340 // Form a mask of all bits from the lowest bit added through the top.
2341 APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1));
2343 // See if the and mask includes all of these bits.
2344 APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue());
2346 if (AddRHSHighBits == AddRHSHighBitsAnd) {
2347 // Okay, the xform is safe. Insert the new add pronto.
2348 Value *NewAdd = Builder->CreateAdd(X, CRHS, LHS->getName());
2349 return BinaryOperator::CreateAnd(NewAdd, C2);
2354 // Try to fold constant add into select arguments.
2355 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
2356 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2360 // add (select X 0 (sub n A)) A --> select X A n
2362 SelectInst *SI = dyn_cast<SelectInst>(LHS);
2365 SI = dyn_cast<SelectInst>(RHS);
2368 if (SI && SI->hasOneUse()) {
2369 Value *TV = SI->getTrueValue();
2370 Value *FV = SI->getFalseValue();
2373 // Can we fold the add into the argument of the select?
2374 // We check both true and false select arguments for a matching subtract.
2375 if (match(FV, m_Zero()) &&
2376 match(TV, m_Sub(m_Value(N), m_Specific(A))))
2377 // Fold the add into the true select value.
2378 return SelectInst::Create(SI->getCondition(), N, A);
2379 if (match(TV, m_Zero()) &&
2380 match(FV, m_Sub(m_Value(N), m_Specific(A))))
2381 // Fold the add into the false select value.
2382 return SelectInst::Create(SI->getCondition(), A, N);
2386 // Check for (add (sext x), y), see if we can merge this into an
2387 // integer add followed by a sext.
2388 if (SExtInst *LHSConv = dyn_cast<SExtInst>(LHS)) {
2389 // (add (sext x), cst) --> (sext (add x, cst'))
2390 if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
2392 ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType());
2393 if (LHSConv->hasOneUse() &&
2394 ConstantExpr::getSExt(CI, I.getType()) == RHSC &&
2395 WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
2396 // Insert the new, smaller add.
2397 Value *NewAdd = Builder->CreateAdd(LHSConv->getOperand(0),
2399 return new SExtInst(NewAdd, I.getType());
2403 // (add (sext x), (sext y)) --> (sext (add int x, y))
2404 if (SExtInst *RHSConv = dyn_cast<SExtInst>(RHS)) {
2405 // Only do this if x/y have the same type, if at last one of them has a
2406 // single use (so we don't increase the number of sexts), and if the
2407 // integer add will not overflow.
2408 if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
2409 (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
2410 WillNotOverflowSignedAdd(LHSConv->getOperand(0),
2411 RHSConv->getOperand(0))) {
2412 // Insert the new integer add.
2413 Value *NewAdd = Builder->CreateAdd(LHSConv->getOperand(0),
2414 RHSConv->getOperand(0), "addconv");
2415 return new SExtInst(NewAdd, I.getType());
2420 return Changed ? &I : 0;
2423 Instruction *InstCombiner::visitFAdd(BinaryOperator &I) {
2424 bool Changed = SimplifyCommutative(I);
2425 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
2427 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
2429 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
2430 if (CFP->isExactlyValue(ConstantFP::getNegativeZero
2431 (I.getType())->getValueAPF()))
2432 return ReplaceInstUsesWith(I, LHS);
2435 if (isa<PHINode>(LHS))
2436 if (Instruction *NV = FoldOpIntoPhi(I))
2441 // -A + -B --> -(A + B)
2442 if (Value *LHSV = dyn_castFNegVal(LHS))
2443 return BinaryOperator::CreateFSub(RHS, LHSV);
2446 if (!isa<Constant>(RHS))
2447 if (Value *V = dyn_castFNegVal(RHS))
2448 return BinaryOperator::CreateFSub(LHS, V);
2450 // Check for X+0.0. Simplify it to X if we know X is not -0.0.
2451 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS))
2452 if (CFP->getValueAPF().isPosZero() && CannotBeNegativeZero(LHS))
2453 return ReplaceInstUsesWith(I, LHS);
2455 // Check for (add double (sitofp x), y), see if we can merge this into an
2456 // integer add followed by a promotion.
2457 if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) {
2458 // (add double (sitofp x), fpcst) --> (sitofp (add int x, intcst))
2459 // ... if the constant fits in the integer value. This is useful for things
2460 // like (double)(x & 1234) + 4.0 -> (double)((X & 1234)+4) which no longer
2461 // requires a constant pool load, and generally allows the add to be better
2463 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) {
2465 ConstantExpr::getFPToSI(CFP, LHSConv->getOperand(0)->getType());
2466 if (LHSConv->hasOneUse() &&
2467 ConstantExpr::getSIToFP(CI, I.getType()) == CFP &&
2468 WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
2469 // Insert the new integer add.
2470 Value *NewAdd = Builder->CreateAdd(LHSConv->getOperand(0),
2472 return new SIToFPInst(NewAdd, I.getType());
2476 // (add double (sitofp x), (sitofp y)) --> (sitofp (add int x, y))
2477 if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) {
2478 // Only do this if x/y have the same type, if at last one of them has a
2479 // single use (so we don't increase the number of int->fp conversions),
2480 // and if the integer add will not overflow.
2481 if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
2482 (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
2483 WillNotOverflowSignedAdd(LHSConv->getOperand(0),
2484 RHSConv->getOperand(0))) {
2485 // Insert the new integer add.
2486 Value *NewAdd = Builder->CreateAdd(LHSConv->getOperand(0),
2487 RHSConv->getOperand(0), "addconv");
2488 return new SIToFPInst(NewAdd, I.getType());
2493 return Changed ? &I : 0;
2496 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
2497 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2499 if (Op0 == Op1) // sub X, X -> 0
2500 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2502 // If this is a 'B = x-(-A)', change to B = x+A...
2503 if (Value *V = dyn_castNegVal(Op1))
2504 return BinaryOperator::CreateAdd(Op0, V);
2506 if (isa<UndefValue>(Op0))
2507 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
2508 if (isa<UndefValue>(Op1))
2509 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
2511 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
2512 // Replace (-1 - A) with (~A)...
2513 if (C->isAllOnesValue())
2514 return BinaryOperator::CreateNot(Op1);
2516 // C - ~X == X + (1+C)
2518 if (match(Op1, m_Not(m_Value(X))))
2519 return BinaryOperator::CreateAdd(X, AddOne(C));
2521 // -(X >>u 31) -> (X >>s 31)
2522 // -(X >>s 31) -> (X >>u 31)
2524 if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1)) {
2525 if (SI->getOpcode() == Instruction::LShr) {
2526 if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
2527 // Check to see if we are shifting out everything but the sign bit.
2528 if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
2529 SI->getType()->getPrimitiveSizeInBits()-1) {
2530 // Ok, the transformation is safe. Insert AShr.
2531 return BinaryOperator::Create(Instruction::AShr,
2532 SI->getOperand(0), CU, SI->getName());
2536 else if (SI->getOpcode() == Instruction::AShr) {
2537 if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
2538 // Check to see if we are shifting out everything but the sign bit.
2539 if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
2540 SI->getType()->getPrimitiveSizeInBits()-1) {
2541 // Ok, the transformation is safe. Insert LShr.
2542 return BinaryOperator::CreateLShr(
2543 SI->getOperand(0), CU, SI->getName());
2550 // Try to fold constant sub into select arguments.
2551 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
2552 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2555 // C - zext(bool) -> bool ? C - 1 : C
2556 if (ZExtInst *ZI = dyn_cast<ZExtInst>(Op1))
2557 if (ZI->getSrcTy() == Type::getInt1Ty(*Context))
2558 return SelectInst::Create(ZI->getOperand(0), SubOne(C), C);
2561 if (I.getType() == Type::getInt1Ty(*Context))
2562 return BinaryOperator::CreateXor(Op0, Op1);
2564 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
2565 if (Op1I->getOpcode() == Instruction::Add) {
2566 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
2567 return BinaryOperator::CreateNeg(Op1I->getOperand(1),
2569 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
2570 return BinaryOperator::CreateNeg(Op1I->getOperand(0),
2572 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
2573 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
2574 // C1-(X+C2) --> (C1-C2)-X
2575 return BinaryOperator::CreateSub(
2576 ConstantExpr::getSub(CI1, CI2), Op1I->getOperand(0));
2580 if (Op1I->hasOneUse()) {
2581 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
2582 // is not used by anyone else...
2584 if (Op1I->getOpcode() == Instruction::Sub) {
2585 // Swap the two operands of the subexpr...
2586 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
2587 Op1I->setOperand(0, IIOp1);
2588 Op1I->setOperand(1, IIOp0);
2590 // Create the new top level add instruction...
2591 return BinaryOperator::CreateAdd(Op0, Op1);
2594 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
2596 if (Op1I->getOpcode() == Instruction::And &&
2597 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
2598 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
2600 Value *NewNot = Builder->CreateNot(OtherOp, "B.not");
2601 return BinaryOperator::CreateAnd(Op0, NewNot);
2604 // 0 - (X sdiv C) -> (X sdiv -C)
2605 if (Op1I->getOpcode() == Instruction::SDiv)
2606 if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
2608 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
2609 return BinaryOperator::CreateSDiv(Op1I->getOperand(0),
2610 ConstantExpr::getNeg(DivRHS));
2612 // X - X*C --> X * (1-C)
2613 ConstantInt *C2 = 0;
2614 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
2616 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1),
2618 return BinaryOperator::CreateMul(Op0, CP1);
2623 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2624 if (Op0I->getOpcode() == Instruction::Add) {
2625 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
2626 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2627 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
2628 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2629 } else if (Op0I->getOpcode() == Instruction::Sub) {
2630 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
2631 return BinaryOperator::CreateNeg(Op0I->getOperand(1),
2637 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
2638 if (X == Op1) // X*C - X --> X * (C-1)
2639 return BinaryOperator::CreateMul(Op1, SubOne(C1));
2641 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
2642 if (X == dyn_castFoldableMul(Op1, C2))
2643 return BinaryOperator::CreateMul(X, ConstantExpr::getSub(C1, C2));
2648 Instruction *InstCombiner::visitFSub(BinaryOperator &I) {
2649 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2651 // If this is a 'B = x-(-A)', change to B = x+A...
2652 if (Value *V = dyn_castFNegVal(Op1))
2653 return BinaryOperator::CreateFAdd(Op0, V);
2655 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
2656 if (Op1I->getOpcode() == Instruction::FAdd) {
2657 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
2658 return BinaryOperator::CreateFNeg(Op1I->getOperand(1),
2660 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
2661 return BinaryOperator::CreateFNeg(Op1I->getOperand(0),
2669 /// isSignBitCheck - Given an exploded icmp instruction, return true if the
2670 /// comparison only checks the sign bit. If it only checks the sign bit, set
2671 /// TrueIfSigned if the result of the comparison is true when the input value is
2673 static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS,
2674 bool &TrueIfSigned) {
2676 case ICmpInst::ICMP_SLT: // True if LHS s< 0
2677 TrueIfSigned = true;
2678 return RHS->isZero();
2679 case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1
2680 TrueIfSigned = true;
2681 return RHS->isAllOnesValue();
2682 case ICmpInst::ICMP_SGT: // True if LHS s> -1
2683 TrueIfSigned = false;
2684 return RHS->isAllOnesValue();
2685 case ICmpInst::ICMP_UGT:
2686 // True if LHS u> RHS and RHS == high-bit-mask - 1
2687 TrueIfSigned = true;
2688 return RHS->getValue() ==
2689 APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits());
2690 case ICmpInst::ICMP_UGE:
2691 // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
2692 TrueIfSigned = true;
2693 return RHS->getValue().isSignBit();
2699 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
2700 bool Changed = SimplifyCommutative(I);
2701 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2703 if (isa<UndefValue>(Op1)) // undef * X -> 0
2704 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2706 // Simplify mul instructions with a constant RHS.
2707 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
2708 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1C)) {
2710 // ((X << C1)*C2) == (X * (C2 << C1))
2711 if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
2712 if (SI->getOpcode() == Instruction::Shl)
2713 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
2714 return BinaryOperator::CreateMul(SI->getOperand(0),
2715 ConstantExpr::getShl(CI, ShOp));
2718 return ReplaceInstUsesWith(I, Op1C); // X * 0 == 0
2719 if (CI->equalsInt(1)) // X * 1 == X
2720 return ReplaceInstUsesWith(I, Op0);
2721 if (CI->isAllOnesValue()) // X * -1 == 0 - X
2722 return BinaryOperator::CreateNeg(Op0, I.getName());
2724 const APInt& Val = cast<ConstantInt>(CI)->getValue();
2725 if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C
2726 return BinaryOperator::CreateShl(Op0,
2727 ConstantInt::get(Op0->getType(), Val.logBase2()));
2729 } else if (isa<VectorType>(Op1C->getType())) {
2730 if (Op1C->isNullValue())
2731 return ReplaceInstUsesWith(I, Op1C);
2733 if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1C)) {
2734 if (Op1V->isAllOnesValue()) // X * -1 == 0 - X
2735 return BinaryOperator::CreateNeg(Op0, I.getName());
2737 // As above, vector X*splat(1.0) -> X in all defined cases.
2738 if (Constant *Splat = Op1V->getSplatValue()) {
2739 if (ConstantInt *CI = dyn_cast<ConstantInt>(Splat))
2740 if (CI->equalsInt(1))
2741 return ReplaceInstUsesWith(I, Op0);
2746 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
2747 if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() &&
2748 isa<ConstantInt>(Op0I->getOperand(1)) && isa<ConstantInt>(Op1C)) {
2749 // Canonicalize (X+C1)*C2 -> X*C2+C1*C2.
2750 Value *Add = Builder->CreateMul(Op0I->getOperand(0), Op1C, "tmp");
2751 Value *C1C2 = Builder->CreateMul(Op1C, Op0I->getOperand(1));
2752 return BinaryOperator::CreateAdd(Add, C1C2);
2756 // Try to fold constant mul into select arguments.
2757 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2758 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2761 if (isa<PHINode>(Op0))
2762 if (Instruction *NV = FoldOpIntoPhi(I))
2766 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
2767 if (Value *Op1v = dyn_castNegVal(Op1))
2768 return BinaryOperator::CreateMul(Op0v, Op1v);
2770 // (X / Y) * Y = X - (X % Y)
2771 // (X / Y) * -Y = (X % Y) - X
2774 BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0);
2776 (BO->getOpcode() != Instruction::UDiv &&
2777 BO->getOpcode() != Instruction::SDiv)) {
2779 BO = dyn_cast<BinaryOperator>(Op1);
2781 Value *Neg = dyn_castNegVal(Op1C);
2782 if (BO && BO->hasOneUse() &&
2783 (BO->getOperand(1) == Op1C || BO->getOperand(1) == Neg) &&
2784 (BO->getOpcode() == Instruction::UDiv ||
2785 BO->getOpcode() == Instruction::SDiv)) {
2786 Value *Op0BO = BO->getOperand(0), *Op1BO = BO->getOperand(1);
2788 // If the division is exact, X % Y is zero.
2789 if (SDivOperator *SDiv = dyn_cast<SDivOperator>(BO))
2790 if (SDiv->isExact()) {
2792 return ReplaceInstUsesWith(I, Op0BO);
2793 return BinaryOperator::CreateNeg(Op0BO);
2797 if (BO->getOpcode() == Instruction::UDiv)
2798 Rem = Builder->CreateURem(Op0BO, Op1BO);
2800 Rem = Builder->CreateSRem(Op0BO, Op1BO);
2804 return BinaryOperator::CreateSub(Op0BO, Rem);
2805 return BinaryOperator::CreateSub(Rem, Op0BO);
2809 /// i1 mul -> i1 and.
2810 if (I.getType() == Type::getInt1Ty(*Context))
2811 return BinaryOperator::CreateAnd(Op0, Op1);
2813 // X*(1 << Y) --> X << Y
2814 // (1 << Y)*X --> X << Y
2817 if (match(Op0, m_Shl(m_One(), m_Value(Y))))
2818 return BinaryOperator::CreateShl(Op1, Y);
2819 if (match(Op1, m_Shl(m_One(), m_Value(Y))))
2820 return BinaryOperator::CreateShl(Op0, Y);
2823 // If one of the operands of the multiply is a cast from a boolean value, then
2824 // we know the bool is either zero or one, so this is a 'masking' multiply.
2825 // X * Y (where Y is 0 or 1) -> X & (0-Y)
2826 if (!isa<VectorType>(I.getType())) {
2827 // -2 is "-1 << 1" so it is all bits set except the low one.
2828 APInt Negative2(I.getType()->getPrimitiveSizeInBits(), (uint64_t)-2, true);
2830 Value *BoolCast = 0, *OtherOp = 0;
2831 if (MaskedValueIsZero(Op0, Negative2))
2832 BoolCast = Op0, OtherOp = Op1;
2833 else if (MaskedValueIsZero(Op1, Negative2))
2834 BoolCast = Op1, OtherOp = Op0;
2837 Value *V = Builder->CreateSub(Constant::getNullValue(I.getType()),
2839 return BinaryOperator::CreateAnd(V, OtherOp);
2843 return Changed ? &I : 0;
2846 Instruction *InstCombiner::visitFMul(BinaryOperator &I) {
2847 bool Changed = SimplifyCommutative(I);
2848 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2850 // Simplify mul instructions with a constant RHS...
2851 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
2852 if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1C)) {
2853 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
2854 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
2855 if (Op1F->isExactlyValue(1.0))
2856 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
2857 } else if (isa<VectorType>(Op1C->getType())) {
2858 if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1C)) {
2859 // As above, vector X*splat(1.0) -> X in all defined cases.
2860 if (Constant *Splat = Op1V->getSplatValue()) {
2861 if (ConstantFP *F = dyn_cast<ConstantFP>(Splat))
2862 if (F->isExactlyValue(1.0))
2863 return ReplaceInstUsesWith(I, Op0);
2868 // Try to fold constant mul into select arguments.
2869 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2870 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2873 if (isa<PHINode>(Op0))
2874 if (Instruction *NV = FoldOpIntoPhi(I))
2878 if (Value *Op0v = dyn_castFNegVal(Op0)) // -X * -Y = X*Y
2879 if (Value *Op1v = dyn_castFNegVal(Op1))
2880 return BinaryOperator::CreateFMul(Op0v, Op1v);
2882 return Changed ? &I : 0;
2885 /// SimplifyDivRemOfSelect - Try to fold a divide or remainder of a select
2887 bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) {
2888 SelectInst *SI = cast<SelectInst>(I.getOperand(1));
2890 // div/rem X, (Cond ? 0 : Y) -> div/rem X, Y
2891 int NonNullOperand = -1;
2892 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
2893 if (ST->isNullValue())
2895 // div/rem X, (Cond ? Y : 0) -> div/rem X, Y
2896 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
2897 if (ST->isNullValue())
2900 if (NonNullOperand == -1)
2903 Value *SelectCond = SI->getOperand(0);
2905 // Change the div/rem to use 'Y' instead of the select.
2906 I.setOperand(1, SI->getOperand(NonNullOperand));
2908 // Okay, we know we replace the operand of the div/rem with 'Y' with no
2909 // problem. However, the select, or the condition of the select may have
2910 // multiple uses. Based on our knowledge that the operand must be non-zero,
2911 // propagate the known value for the select into other uses of it, and
2912 // propagate a known value of the condition into its other users.
2914 // If the select and condition only have a single use, don't bother with this,
2916 if (SI->use_empty() && SelectCond->hasOneUse())
2919 // Scan the current block backward, looking for other uses of SI.
2920 BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin();
2922 while (BBI != BBFront) {
2924 // If we found a call to a function, we can't assume it will return, so
2925 // information from below it cannot be propagated above it.
2926 if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI))
2929 // Replace uses of the select or its condition with the known values.
2930 for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end();
2933 *I = SI->getOperand(NonNullOperand);
2935 } else if (*I == SelectCond) {
2936 *I = NonNullOperand == 1 ? ConstantInt::getTrue(*Context) :
2937 ConstantInt::getFalse(*Context);
2942 // If we past the instruction, quit looking for it.
2945 if (&*BBI == SelectCond)
2948 // If we ran out of things to eliminate, break out of the loop.
2949 if (SelectCond == 0 && SI == 0)
2957 /// This function implements the transforms on div instructions that work
2958 /// regardless of the kind of div instruction it is (udiv, sdiv, or fdiv). It is
2959 /// used by the visitors to those instructions.
2960 /// @brief Transforms common to all three div instructions
2961 Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) {
2962 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2964 // undef / X -> 0 for integer.
2965 // undef / X -> undef for FP (the undef could be a snan).
2966 if (isa<UndefValue>(Op0)) {
2967 if (Op0->getType()->isFPOrFPVector())
2968 return ReplaceInstUsesWith(I, Op0);
2969 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2972 // X / undef -> undef
2973 if (isa<UndefValue>(Op1))
2974 return ReplaceInstUsesWith(I, Op1);
2979 /// This function implements the transforms common to both integer division
2980 /// instructions (udiv and sdiv). It is called by the visitors to those integer
2981 /// division instructions.
2982 /// @brief Common integer divide transforms
2983 Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
2984 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2986 // (sdiv X, X) --> 1 (udiv X, X) --> 1
2988 if (const VectorType *Ty = dyn_cast<VectorType>(I.getType())) {
2989 Constant *CI = ConstantInt::get(Ty->getElementType(), 1);
2990 std::vector<Constant*> Elts(Ty->getNumElements(), CI);
2991 return ReplaceInstUsesWith(I, ConstantVector::get(Elts));
2994 Constant *CI = ConstantInt::get(I.getType(), 1);
2995 return ReplaceInstUsesWith(I, CI);
2998 if (Instruction *Common = commonDivTransforms(I))
3001 // Handle cases involving: [su]div X, (select Cond, Y, Z)
3002 // This does not apply for fdiv.
3003 if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
3006 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
3008 if (RHS->equalsInt(1))
3009 return ReplaceInstUsesWith(I, Op0);
3011 // (X / C1) / C2 -> X / (C1*C2)
3012 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
3013 if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
3014 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
3015 if (MultiplyOverflows(RHS, LHSRHS,
3016 I.getOpcode()==Instruction::SDiv))
3017 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3019 return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0),
3020 ConstantExpr::getMul(RHS, LHSRHS));
3023 if (!RHS->isZero()) { // avoid X udiv 0
3024 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3025 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3027 if (isa<PHINode>(Op0))
3028 if (Instruction *NV = FoldOpIntoPhi(I))
3033 // 0 / X == 0, we don't need to preserve faults!
3034 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
3035 if (LHS->equalsInt(0))
3036 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3038 // It can't be division by zero, hence it must be division by one.
3039 if (I.getType() == Type::getInt1Ty(*Context))
3040 return ReplaceInstUsesWith(I, Op0);
3042 if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1)) {
3043 if (ConstantInt *X = cast_or_null<ConstantInt>(Op1V->getSplatValue()))
3046 return ReplaceInstUsesWith(I, Op0);
3052 Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
3053 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3055 // Handle the integer div common cases
3056 if (Instruction *Common = commonIDivTransforms(I))
3059 if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
3060 // X udiv C^2 -> X >> C
3061 // Check to see if this is an unsigned division with an exact power of 2,
3062 // if so, convert to a right shift.
3063 if (C->getValue().isPowerOf2()) // 0 not included in isPowerOf2
3064 return BinaryOperator::CreateLShr(Op0,
3065 ConstantInt::get(Op0->getType(), C->getValue().logBase2()));
3067 // X udiv C, where C >= signbit
3068 if (C->getValue().isNegative()) {
3069 Value *IC = Builder->CreateICmpULT( Op0, C);
3070 return SelectInst::Create(IC, Constant::getNullValue(I.getType()),
3071 ConstantInt::get(I.getType(), 1));
3075 // X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
3076 if (BinaryOperator *RHSI = dyn_cast<BinaryOperator>(I.getOperand(1))) {
3077 if (RHSI->getOpcode() == Instruction::Shl &&
3078 isa<ConstantInt>(RHSI->getOperand(0))) {
3079 const APInt& C1 = cast<ConstantInt>(RHSI->getOperand(0))->getValue();
3080 if (C1.isPowerOf2()) {
3081 Value *N = RHSI->getOperand(1);
3082 const Type *NTy = N->getType();
3083 if (uint32_t C2 = C1.logBase2())
3084 N = Builder->CreateAdd(N, ConstantInt::get(NTy, C2), "tmp");
3085 return BinaryOperator::CreateLShr(Op0, N);
3090 // udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
3091 // where C1&C2 are powers of two.
3092 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
3093 if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
3094 if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
3095 const APInt &TVA = STO->getValue(), &FVA = SFO->getValue();
3096 if (TVA.isPowerOf2() && FVA.isPowerOf2()) {
3097 // Compute the shift amounts
3098 uint32_t TSA = TVA.logBase2(), FSA = FVA.logBase2();
3099 // Construct the "on true" case of the select
3100 Constant *TC = ConstantInt::get(Op0->getType(), TSA);
3101 Value *TSI = Builder->CreateLShr(Op0, TC, SI->getName()+".t");
3103 // Construct the "on false" case of the select
3104 Constant *FC = ConstantInt::get(Op0->getType(), FSA);
3105 Value *FSI = Builder->CreateLShr(Op0, FC, SI->getName()+".f");
3107 // construct the select instruction and return it.
3108 return SelectInst::Create(SI->getOperand(0), TSI, FSI, SI->getName());
3114 Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
3115 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3117 // Handle the integer div common cases
3118 if (Instruction *Common = commonIDivTransforms(I))
3121 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
3123 if (RHS->isAllOnesValue())
3124 return BinaryOperator::CreateNeg(Op0);
3126 // sdiv X, C --> ashr X, log2(C)
3127 if (cast<SDivOperator>(&I)->isExact() &&
3128 RHS->getValue().isNonNegative() &&
3129 RHS->getValue().isPowerOf2()) {
3130 Value *ShAmt = llvm::ConstantInt::get(RHS->getType(),
3131 RHS->getValue().exactLogBase2());
3132 return BinaryOperator::CreateAShr(Op0, ShAmt, I.getName());
3135 // -X/C --> X/-C provided the negation doesn't overflow.
3136 if (SubOperator *Sub = dyn_cast<SubOperator>(Op0))
3137 if (isa<Constant>(Sub->getOperand(0)) &&
3138 cast<Constant>(Sub->getOperand(0))->isNullValue() &&
3139 Sub->hasNoSignedWrap())
3140 return BinaryOperator::CreateSDiv(Sub->getOperand(1),
3141 ConstantExpr::getNeg(RHS));
3144 // If the sign bits of both operands are zero (i.e. we can prove they are
3145 // unsigned inputs), turn this into a udiv.
3146 if (I.getType()->isInteger()) {
3147 APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
3148 if (MaskedValueIsZero(Op0, Mask)) {
3149 if (MaskedValueIsZero(Op1, Mask)) {
3150 // X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
3151 return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
3153 ConstantInt *ShiftedInt;
3154 if (match(Op1, m_Shl(m_ConstantInt(ShiftedInt), m_Value())) &&
3155 ShiftedInt->getValue().isPowerOf2()) {
3156 // X sdiv (1 << Y) -> X udiv (1 << Y) ( -> X u>> Y)
3157 // Safe because the only negative value (1 << Y) can take on is
3158 // INT_MIN, and X sdiv INT_MIN == X udiv INT_MIN == 0 if X doesn't have
3159 // the sign bit set.
3160 return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
3168 Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
3169 return commonDivTransforms(I);
3172 /// This function implements the transforms on rem instructions that work
3173 /// regardless of the kind of rem instruction it is (urem, srem, or frem). It
3174 /// is used by the visitors to those instructions.
3175 /// @brief Transforms common to all three rem instructions
3176 Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
3177 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3179 if (isa<UndefValue>(Op0)) { // undef % X -> 0
3180 if (I.getType()->isFPOrFPVector())
3181 return ReplaceInstUsesWith(I, Op0); // X % undef -> undef (could be SNaN)
3182 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3184 if (isa<UndefValue>(Op1))
3185 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
3187 // Handle cases involving: rem X, (select Cond, Y, Z)
3188 if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
3194 /// This function implements the transforms common to both integer remainder
3195 /// instructions (urem and srem). It is called by the visitors to those integer
3196 /// remainder instructions.
3197 /// @brief Common integer remainder transforms
3198 Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
3199 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3201 if (Instruction *common = commonRemTransforms(I))
3204 // 0 % X == 0 for integer, we don't need to preserve faults!
3205 if (Constant *LHS = dyn_cast<Constant>(Op0))
3206 if (LHS->isNullValue())
3207 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3209 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
3210 // X % 0 == undef, we don't need to preserve faults!
3211 if (RHS->equalsInt(0))
3212 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
3214 if (RHS->equalsInt(1)) // X % 1 == 0
3215 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3217 if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
3218 if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
3219 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3221 } else if (isa<PHINode>(Op0I)) {
3222 if (Instruction *NV = FoldOpIntoPhi(I))
3226 // See if we can fold away this rem instruction.
3227 if (SimplifyDemandedInstructionBits(I))
3235 Instruction *InstCombiner::visitURem(BinaryOperator &I) {
3236 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3238 if (Instruction *common = commonIRemTransforms(I))
3241 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
3242 // X urem C^2 -> X and C
3243 // Check to see if this is an unsigned remainder with an exact power of 2,
3244 // if so, convert to a bitwise and.
3245 if (ConstantInt *C = dyn_cast<ConstantInt>(RHS))
3246 if (C->getValue().isPowerOf2())
3247 return BinaryOperator::CreateAnd(Op0, SubOne(C));
3250 if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
3251 // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1)
3252 if (RHSI->getOpcode() == Instruction::Shl &&
3253 isa<ConstantInt>(RHSI->getOperand(0))) {
3254 if (cast<ConstantInt>(RHSI->getOperand(0))->getValue().isPowerOf2()) {
3255 Constant *N1 = Constant::getAllOnesValue(I.getType());
3256 Value *Add = Builder->CreateAdd(RHSI, N1, "tmp");
3257 return BinaryOperator::CreateAnd(Op0, Add);
3262 // urem X, (select Cond, 2^C1, 2^C2) --> select Cond, (and X, C1), (and X, C2)
3263 // where C1&C2 are powers of two.
3264 if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
3265 if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
3266 if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
3267 // STO == 0 and SFO == 0 handled above.
3268 if ((STO->getValue().isPowerOf2()) &&
3269 (SFO->getValue().isPowerOf2())) {
3270 Value *TrueAnd = Builder->CreateAnd(Op0, SubOne(STO),
3271 SI->getName()+".t");
3272 Value *FalseAnd = Builder->CreateAnd(Op0, SubOne(SFO),
3273 SI->getName()+".f");
3274 return SelectInst::Create(SI->getOperand(0), TrueAnd, FalseAnd);
3282 Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
3283 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3285 // Handle the integer rem common cases
3286 if (Instruction *Common = commonIRemTransforms(I))
3289 if (Value *RHSNeg = dyn_castNegVal(Op1))
3290 if (!isa<Constant>(RHSNeg) ||
3291 (isa<ConstantInt>(RHSNeg) &&
3292 cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive())) {
3294 Worklist.AddValue(I.getOperand(1));
3295 I.setOperand(1, RHSNeg);
3299 // If the sign bits of both operands are zero (i.e. we can prove they are
3300 // unsigned inputs), turn this into a urem.
3301 if (I.getType()->isInteger()) {
3302 APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
3303 if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
3304 // X srem Y -> X urem Y, iff X and Y don't have sign bit set
3305 return BinaryOperator::CreateURem(Op0, Op1, I.getName());
3309 // If it's a constant vector, flip any negative values positive.
3310 if (ConstantVector *RHSV = dyn_cast<ConstantVector>(Op1)) {
3311 unsigned VWidth = RHSV->getNumOperands();
3313 bool hasNegative = false;
3314 for (unsigned i = 0; !hasNegative && i != VWidth; ++i)
3315 if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i)))
3316 if (RHS->getValue().isNegative())
3320 std::vector<Constant *> Elts(VWidth);
3321 for (unsigned i = 0; i != VWidth; ++i) {
3322 if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i))) {
3323 if (RHS->getValue().isNegative())
3324 Elts[i] = cast<ConstantInt>(ConstantExpr::getNeg(RHS));
3330 Constant *NewRHSV = ConstantVector::get(Elts);
3331 if (NewRHSV != RHSV) {
3332 Worklist.AddValue(I.getOperand(1));
3333 I.setOperand(1, NewRHSV);
3342 Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
3343 return commonRemTransforms(I);
3346 // isOneBitSet - Return true if there is exactly one bit set in the specified
3348 static bool isOneBitSet(const ConstantInt *CI) {
3349 return CI->getValue().isPowerOf2();
3352 // isHighOnes - Return true if the constant is of the form 1+0+.
3353 // This is the same as lowones(~X).
3354 static bool isHighOnes(const ConstantInt *CI) {
3355 return (~CI->getValue() + 1).isPowerOf2();
3358 /// getICmpCode - Encode a icmp predicate into a three bit mask. These bits
3359 /// are carefully arranged to allow folding of expressions such as:
3361 /// (A < B) | (A > B) --> (A != B)
3363 /// Note that this is only valid if the first and second predicates have the
3364 /// same sign. Is illegal to do: (A u< B) | (A s> B)
3366 /// Three bits are used to represent the condition, as follows:
3371 /// <=> Value Definition
3372 /// 000 0 Always false
3379 /// 111 7 Always true
3381 static unsigned getICmpCode(const ICmpInst *ICI) {
3382 switch (ICI->getPredicate()) {
3384 case ICmpInst::ICMP_UGT: return 1; // 001
3385 case ICmpInst::ICMP_SGT: return 1; // 001
3386 case ICmpInst::ICMP_EQ: return 2; // 010
3387 case ICmpInst::ICMP_UGE: return 3; // 011
3388 case ICmpInst::ICMP_SGE: return 3; // 011
3389 case ICmpInst::ICMP_ULT: return 4; // 100
3390 case ICmpInst::ICMP_SLT: return 4; // 100
3391 case ICmpInst::ICMP_NE: return 5; // 101
3392 case ICmpInst::ICMP_ULE: return 6; // 110
3393 case ICmpInst::ICMP_SLE: return 6; // 110
3396 llvm_unreachable("Invalid ICmp predicate!");
3401 /// getFCmpCode - Similar to getICmpCode but for FCmpInst. This encodes a fcmp
3402 /// predicate into a three bit mask. It also returns whether it is an ordered
3403 /// predicate by reference.
3404 static unsigned getFCmpCode(FCmpInst::Predicate CC, bool &isOrdered) {
3407 case FCmpInst::FCMP_ORD: isOrdered = true; return 0; // 000
3408 case FCmpInst::FCMP_UNO: return 0; // 000
3409 case FCmpInst::FCMP_OGT: isOrdered = true; return 1; // 001
3410 case FCmpInst::FCMP_UGT: return 1; // 001
3411 case FCmpInst::FCMP_OEQ: isOrdered = true; return 2; // 010
3412 case FCmpInst::FCMP_UEQ: return 2; // 010
3413 case FCmpInst::FCMP_OGE: isOrdered = true; return 3; // 011
3414 case FCmpInst::FCMP_UGE: return 3; // 011
3415 case FCmpInst::FCMP_OLT: isOrdered = true; return 4; // 100
3416 case FCmpInst::FCMP_ULT: return 4; // 100
3417 case FCmpInst::FCMP_ONE: isOrdered = true; return 5; // 101
3418 case FCmpInst::FCMP_UNE: return 5; // 101
3419 case FCmpInst::FCMP_OLE: isOrdered = true; return 6; // 110
3420 case FCmpInst::FCMP_ULE: return 6; // 110
3423 // Not expecting FCMP_FALSE and FCMP_TRUE;
3424 llvm_unreachable("Unexpected FCmp predicate!");
3429 /// getICmpValue - This is the complement of getICmpCode, which turns an
3430 /// opcode and two operands into either a constant true or false, or a brand
3431 /// new ICmp instruction. The sign is passed in to determine which kind
3432 /// of predicate to use in the new icmp instruction.
3433 static Value *getICmpValue(bool sign, unsigned code, Value *LHS, Value *RHS,
3434 LLVMContext *Context) {
3436 default: llvm_unreachable("Illegal ICmp code!");
3437 case 0: return ConstantInt::getFalse(*Context);
3440 return new ICmpInst(ICmpInst::ICMP_SGT, LHS, RHS);
3442 return new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS);
3443 case 2: return new ICmpInst(ICmpInst::ICMP_EQ, LHS, RHS);
3446 return new ICmpInst(ICmpInst::ICMP_SGE, LHS, RHS);
3448 return new ICmpInst(ICmpInst::ICMP_UGE, LHS, RHS);
3451 return new ICmpInst(ICmpInst::ICMP_SLT, LHS, RHS);
3453 return new ICmpInst(ICmpInst::ICMP_ULT, LHS, RHS);
3454 case 5: return new ICmpInst(ICmpInst::ICMP_NE, LHS, RHS);
3457 return new ICmpInst(ICmpInst::ICMP_SLE, LHS, RHS);
3459 return new ICmpInst(ICmpInst::ICMP_ULE, LHS, RHS);
3460 case 7: return ConstantInt::getTrue(*Context);
3464 /// getFCmpValue - This is the complement of getFCmpCode, which turns an
3465 /// opcode and two operands into either a FCmp instruction. isordered is passed
3466 /// in to determine which kind of predicate to use in the new fcmp instruction.
3467 static Value *getFCmpValue(bool isordered, unsigned code,
3468 Value *LHS, Value *RHS, LLVMContext *Context) {
3470 default: llvm_unreachable("Illegal FCmp code!");
3473 return new FCmpInst(FCmpInst::FCMP_ORD, LHS, RHS);
3475 return new FCmpInst(FCmpInst::FCMP_UNO, LHS, RHS);
3478 return new FCmpInst(FCmpInst::FCMP_OGT, LHS, RHS);
3480 return new FCmpInst(FCmpInst::FCMP_UGT, LHS, RHS);
3483 return new FCmpInst(FCmpInst::FCMP_OEQ, LHS, RHS);
3485 return new FCmpInst(FCmpInst::FCMP_UEQ, LHS, RHS);
3488 return new FCmpInst(FCmpInst::FCMP_OGE, LHS, RHS);
3490 return new FCmpInst(FCmpInst::FCMP_UGE, LHS, RHS);
3493 return new FCmpInst(FCmpInst::FCMP_OLT, LHS, RHS);
3495 return new FCmpInst(FCmpInst::FCMP_ULT, LHS, RHS);
3498 return new FCmpInst(FCmpInst::FCMP_ONE, LHS, RHS);
3500 return new FCmpInst(FCmpInst::FCMP_UNE, LHS, RHS);
3503 return new FCmpInst(FCmpInst::FCMP_OLE, LHS, RHS);
3505 return new FCmpInst(FCmpInst::FCMP_ULE, LHS, RHS);
3506 case 7: return ConstantInt::getTrue(*Context);
3510 /// PredicatesFoldable - Return true if both predicates match sign or if at
3511 /// least one of them is an equality comparison (which is signless).
3512 static bool PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
3513 return (ICmpInst::isSignedPredicate(p1) == ICmpInst::isSignedPredicate(p2)) ||
3514 (ICmpInst::isSignedPredicate(p1) && ICmpInst::isEquality(p2)) ||
3515 (ICmpInst::isSignedPredicate(p2) && ICmpInst::isEquality(p1));
3519 // FoldICmpLogical - Implements (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
3520 struct FoldICmpLogical {
3523 ICmpInst::Predicate pred;
3524 FoldICmpLogical(InstCombiner &ic, ICmpInst *ICI)
3525 : IC(ic), LHS(ICI->getOperand(0)), RHS(ICI->getOperand(1)),
3526 pred(ICI->getPredicate()) {}
3527 bool shouldApply(Value *V) const {
3528 if (ICmpInst *ICI = dyn_cast<ICmpInst>(V))
3529 if (PredicatesFoldable(pred, ICI->getPredicate()))
3530 return ((ICI->getOperand(0) == LHS && ICI->getOperand(1) == RHS) ||
3531 (ICI->getOperand(0) == RHS && ICI->getOperand(1) == LHS));
3534 Instruction *apply(Instruction &Log) const {
3535 ICmpInst *ICI = cast<ICmpInst>(Log.getOperand(0));
3536 if (ICI->getOperand(0) != LHS) {
3537 assert(ICI->getOperand(1) == LHS);
3538 ICI->swapOperands(); // Swap the LHS and RHS of the ICmp
3541 ICmpInst *RHSICI = cast<ICmpInst>(Log.getOperand(1));
3542 unsigned LHSCode = getICmpCode(ICI);
3543 unsigned RHSCode = getICmpCode(RHSICI);
3545 switch (Log.getOpcode()) {
3546 case Instruction::And: Code = LHSCode & RHSCode; break;
3547 case Instruction::Or: Code = LHSCode | RHSCode; break;
3548 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
3549 default: llvm_unreachable("Illegal logical opcode!"); return 0;
3552 bool isSigned = ICmpInst::isSignedPredicate(RHSICI->getPredicate()) ||
3553 ICmpInst::isSignedPredicate(ICI->getPredicate());
3555 Value *RV = getICmpValue(isSigned, Code, LHS, RHS, IC.getContext());
3556 if (Instruction *I = dyn_cast<Instruction>(RV))
3558 // Otherwise, it's a constant boolean value...
3559 return IC.ReplaceInstUsesWith(Log, RV);
3562 } // end anonymous namespace
3564 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
3565 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
3566 // guaranteed to be a binary operator.
3567 Instruction *InstCombiner::OptAndOp(Instruction *Op,
3569 ConstantInt *AndRHS,
3570 BinaryOperator &TheAnd) {
3571 Value *X = Op->getOperand(0);
3572 Constant *Together = 0;
3574 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
3576 switch (Op->getOpcode()) {
3577 case Instruction::Xor:
3578 if (Op->hasOneUse()) {
3579 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
3580 Value *And = Builder->CreateAnd(X, AndRHS);
3582 return BinaryOperator::CreateXor(And, Together);
3585 case Instruction::Or:
3586 if (Together == AndRHS) // (X | C) & C --> C
3587 return ReplaceInstUsesWith(TheAnd, AndRHS);
3589 if (Op->hasOneUse() && Together != OpRHS) {
3590 // (X | C1) & C2 --> (X | (C1&C2)) & C2
3591 Value *Or = Builder->CreateOr(X, Together);
3593 return BinaryOperator::CreateAnd(Or, AndRHS);
3596 case Instruction::Add:
3597 if (Op->hasOneUse()) {
3598 // Adding a one to a single bit bit-field should be turned into an XOR
3599 // of the bit. First thing to check is to see if this AND is with a
3600 // single bit constant.
3601 const APInt& AndRHSV = cast<ConstantInt>(AndRHS)->getValue();
3603 // If there is only one bit set...
3604 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
3605 // Ok, at this point, we know that we are masking the result of the
3606 // ADD down to exactly one bit. If the constant we are adding has
3607 // no bits set below this bit, then we can eliminate the ADD.
3608 const APInt& AddRHS = cast<ConstantInt>(OpRHS)->getValue();
3610 // Check to see if any bits below the one bit set in AndRHSV are set.
3611 if ((AddRHS & (AndRHSV-1)) == 0) {
3612 // If not, the only thing that can effect the output of the AND is
3613 // the bit specified by AndRHSV. If that bit is set, the effect of
3614 // the XOR is to toggle the bit. If it is clear, then the ADD has
3616 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
3617 TheAnd.setOperand(0, X);
3620 // Pull the XOR out of the AND.
3621 Value *NewAnd = Builder->CreateAnd(X, AndRHS);
3622 NewAnd->takeName(Op);
3623 return BinaryOperator::CreateXor(NewAnd, AndRHS);
3630 case Instruction::Shl: {
3631 // We know that the AND will not produce any of the bits shifted in, so if
3632 // the anded constant includes them, clear them now!
3634 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
3635 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
3636 APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal));
3637 ConstantInt *CI = ConstantInt::get(*Context, AndRHS->getValue() & ShlMask);
3639 if (CI->getValue() == ShlMask) {
3640 // Masking out bits that the shift already masks
3641 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
3642 } else if (CI != AndRHS) { // Reducing bits set in and.
3643 TheAnd.setOperand(1, CI);
3648 case Instruction::LShr:
3650 // We know that the AND will not produce any of the bits shifted in, so if
3651 // the anded constant includes them, clear them now! This only applies to
3652 // unsigned shifts, because a signed shr may bring in set bits!
3654 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
3655 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
3656 APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
3657 ConstantInt *CI = ConstantInt::get(*Context, AndRHS->getValue() & ShrMask);
3659 if (CI->getValue() == ShrMask) {
3660 // Masking out bits that the shift already masks.
3661 return ReplaceInstUsesWith(TheAnd, Op);
3662 } else if (CI != AndRHS) {
3663 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
3668 case Instruction::AShr:
3670 // See if this is shifting in some sign extension, then masking it out
3672 if (Op->hasOneUse()) {
3673 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
3674 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
3675 APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
3676 Constant *C = ConstantInt::get(*Context, AndRHS->getValue() & ShrMask);
3677 if (C == AndRHS) { // Masking out bits shifted in.
3678 // (Val ashr C1) & C2 -> (Val lshr C1) & C2
3679 // Make the argument unsigned.
3680 Value *ShVal = Op->getOperand(0);
3681 ShVal = Builder->CreateLShr(ShVal, OpRHS, Op->getName());
3682 return BinaryOperator::CreateAnd(ShVal, AndRHS, TheAnd.getName());
3691 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
3692 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
3693 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. isSigned indicates
3694 /// whether to treat the V, Lo and HI as signed or not. IB is the location to
3695 /// insert new instructions.
3696 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
3697 bool isSigned, bool Inside,
3699 assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ?
3700 ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() &&
3701 "Lo is not <= Hi in range emission code!");
3704 if (Lo == Hi) // Trivially false.
3705 return new ICmpInst(ICmpInst::ICMP_NE, V, V);
3707 // V >= Min && V < Hi --> V < Hi
3708 if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
3709 ICmpInst::Predicate pred = (isSigned ?
3710 ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT);
3711 return new ICmpInst(pred, V, Hi);
3714 // Emit V-Lo <u Hi-Lo
3715 Constant *NegLo = ConstantExpr::getNeg(Lo);
3716 Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off");
3717 Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi);
3718 return new ICmpInst(ICmpInst::ICMP_ULT, Add, UpperBound);
3721 if (Lo == Hi) // Trivially true.
3722 return new ICmpInst(ICmpInst::ICMP_EQ, V, V);
3724 // V < Min || V >= Hi -> V > Hi-1
3725 Hi = SubOne(cast<ConstantInt>(Hi));
3726 if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
3727 ICmpInst::Predicate pred = (isSigned ?
3728 ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT);
3729 return new ICmpInst(pred, V, Hi);
3732 // Emit V-Lo >u Hi-1-Lo
3733 // Note that Hi has already had one subtracted from it, above.
3734 ConstantInt *NegLo = cast<ConstantInt>(ConstantExpr::getNeg(Lo));
3735 Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off");
3736 Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi);
3737 return new ICmpInst(ICmpInst::ICMP_UGT, Add, LowerBound);
3740 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
3741 // any number of 0s on either side. The 1s are allowed to wrap from LSB to
3742 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
3743 // not, since all 1s are not contiguous.
3744 static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) {
3745 const APInt& V = Val->getValue();
3746 uint32_t BitWidth = Val->getType()->getBitWidth();
3747 if (!APIntOps::isShiftedMask(BitWidth, V)) return false;
3749 // look for the first zero bit after the run of ones
3750 MB = BitWidth - ((V - 1) ^ V).countLeadingZeros();
3751 // look for the first non-zero bit
3752 ME = V.getActiveBits();
3756 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
3757 /// where isSub determines whether the operator is a sub. If we can fold one of
3758 /// the following xforms:
3760 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
3761 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
3762 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
3764 /// return (A +/- B).
3766 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
3767 ConstantInt *Mask, bool isSub,
3769 Instruction *LHSI = dyn_cast<Instruction>(LHS);
3770 if (!LHSI || LHSI->getNumOperands() != 2 ||
3771 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
3773 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
3775 switch (LHSI->getOpcode()) {
3777 case Instruction::And:
3778 if (ConstantExpr::getAnd(N, Mask) == Mask) {
3779 // If the AndRHS is a power of two minus one (0+1+), this is simple.
3780 if ((Mask->getValue().countLeadingZeros() +
3781 Mask->getValue().countPopulation()) ==
3782 Mask->getValue().getBitWidth())
3785 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
3786 // part, we don't need any explicit masks to take them out of A. If that
3787 // is all N is, ignore it.
3788 uint32_t MB = 0, ME = 0;
3789 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
3790 uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth();
3791 APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1));
3792 if (MaskedValueIsZero(RHS, Mask))
3797 case Instruction::Or:
3798 case Instruction::Xor:
3799 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
3800 if ((Mask->getValue().countLeadingZeros() +
3801 Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()
3802 && ConstantExpr::getAnd(N, Mask)->isNullValue())
3808 return Builder->CreateSub(LHSI->getOperand(0), RHS, "fold");
3809 return Builder->CreateAdd(LHSI->getOperand(0), RHS, "fold");
3812 /// FoldAndOfICmps - Fold (icmp)&(icmp) if possible.
3813 Instruction *InstCombiner::FoldAndOfICmps(Instruction &I,
3814 ICmpInst *LHS, ICmpInst *RHS) {
3816 ConstantInt *LHSCst, *RHSCst;
3817 ICmpInst::Predicate LHSCC, RHSCC;
3819 // This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2).
3820 if (!match(LHS, m_ICmp(LHSCC, m_Value(Val),
3821 m_ConstantInt(LHSCst))) ||
3822 !match(RHS, m_ICmp(RHSCC, m_Value(Val2),
3823 m_ConstantInt(RHSCst))))
3826 // (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C)
3827 // where C is a power of 2
3828 if (LHSCst == RHSCst && LHSCC == RHSCC && LHSCC == ICmpInst::ICMP_ULT &&
3829 LHSCst->getValue().isPowerOf2()) {
3830 Value *NewOr = Builder->CreateOr(Val, Val2);
3831 return new ICmpInst(LHSCC, NewOr, LHSCst);
3834 // From here on, we only handle:
3835 // (icmp1 A, C1) & (icmp2 A, C2) --> something simpler.
3836 if (Val != Val2) return 0;
3838 // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
3839 if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
3840 RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
3841 LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
3842 RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
3845 // We can't fold (ugt x, C) & (sgt x, C2).
3846 if (!PredicatesFoldable(LHSCC, RHSCC))
3849 // Ensure that the larger constant is on the RHS.
3851 if (ICmpInst::isSignedPredicate(LHSCC) ||
3852 (ICmpInst::isEquality(LHSCC) &&
3853 ICmpInst::isSignedPredicate(RHSCC)))
3854 ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
3856 ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
3859 std::swap(LHS, RHS);
3860 std::swap(LHSCst, RHSCst);
3861 std::swap(LHSCC, RHSCC);
3864 // At this point, we know we have have two icmp instructions
3865 // comparing a value against two constants and and'ing the result
3866 // together. Because of the above check, we know that we only have
3867 // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
3868 // (from the FoldICmpLogical check above), that the two constants
3869 // are not equal and that the larger constant is on the RHS
3870 assert(LHSCst != RHSCst && "Compares not folded above?");
3873 default: llvm_unreachable("Unknown integer condition code!");
3874 case ICmpInst::ICMP_EQ:
3876 default: llvm_unreachable("Unknown integer condition code!");
3877 case ICmpInst::ICMP_EQ: // (X == 13 & X == 15) -> false
3878 case ICmpInst::ICMP_UGT: // (X == 13 & X > 15) -> false
3879 case ICmpInst::ICMP_SGT: // (X == 13 & X > 15) -> false
3880 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
3881 case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13
3882 case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13
3883 case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13
3884 return ReplaceInstUsesWith(I, LHS);
3886 case ICmpInst::ICMP_NE:
3888 default: llvm_unreachable("Unknown integer condition code!");
3889 case ICmpInst::ICMP_ULT:
3890 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13
3891 return new ICmpInst(ICmpInst::ICMP_ULT, Val, LHSCst);
3892 break; // (X != 13 & X u< 15) -> no change
3893 case ICmpInst::ICMP_SLT:
3894 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13
3895 return new ICmpInst(ICmpInst::ICMP_SLT, Val, LHSCst);
3896 break; // (X != 13 & X s< 15) -> no change
3897 case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15
3898 case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15
3899 case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15
3900 return ReplaceInstUsesWith(I, RHS);
3901 case ICmpInst::ICMP_NE:
3902 if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
3903 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
3904 Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
3905 return new ICmpInst(ICmpInst::ICMP_UGT, Add,
3906 ConstantInt::get(Add->getType(), 1));
3908 break; // (X != 13 & X != 15) -> no change
3911 case ICmpInst::ICMP_ULT:
3913 default: llvm_unreachable("Unknown integer condition code!");
3914 case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false
3915 case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false
3916 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
3917 case ICmpInst::ICMP_SGT: // (X u< 13 & X s> 15) -> no change
3919 case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13
3920 case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13
3921 return ReplaceInstUsesWith(I, LHS);
3922 case ICmpInst::ICMP_SLT: // (X u< 13 & X s< 15) -> no change
3926 case ICmpInst::ICMP_SLT:
3928 default: llvm_unreachable("Unknown integer condition code!");
3929 case ICmpInst::ICMP_EQ: // (X s< 13 & X == 15) -> false
3930 case ICmpInst::ICMP_SGT: // (X s< 13 & X s> 15) -> false
3931 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
3932 case ICmpInst::ICMP_UGT: // (X s< 13 & X u> 15) -> no change
3934 case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13
3935 case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13
3936 return ReplaceInstUsesWith(I, LHS);
3937 case ICmpInst::ICMP_ULT: // (X s< 13 & X u< 15) -> no change
3941 case ICmpInst::ICMP_UGT:
3943 default: llvm_unreachable("Unknown integer condition code!");
3944 case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X == 15
3945 case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15
3946 return ReplaceInstUsesWith(I, RHS);
3947 case ICmpInst::ICMP_SGT: // (X u> 13 & X s> 15) -> no change
3949 case ICmpInst::ICMP_NE:
3950 if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14
3951 return new ICmpInst(LHSCC, Val, RHSCst);
3952 break; // (X u> 13 & X != 15) -> no change
3953 case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) <u 1
3954 return InsertRangeTest(Val, AddOne(LHSCst),
3955 RHSCst, false, true, I);
3956 case ICmpInst::ICMP_SLT: // (X u> 13 & X s< 15) -> no change
3960 case ICmpInst::ICMP_SGT:
3962 default: llvm_unreachable("Unknown integer condition code!");
3963 case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X == 15
3964 case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15
3965 return ReplaceInstUsesWith(I, RHS);
3966 case ICmpInst::ICMP_UGT: // (X s> 13 & X u> 15) -> no change
3968 case ICmpInst::ICMP_NE:
3969 if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14
3970 return new ICmpInst(LHSCC, Val, RHSCst);
3971 break; // (X s> 13 & X != 15) -> no change
3972 case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) s< 1
3973 return InsertRangeTest(Val, AddOne(LHSCst),
3974 RHSCst, true, true, I);
3975 case ICmpInst::ICMP_ULT: // (X s> 13 & X u< 15) -> no change
3984 Instruction *InstCombiner::FoldAndOfFCmps(Instruction &I, FCmpInst *LHS,
3987 if (LHS->getPredicate() == FCmpInst::FCMP_ORD &&
3988 RHS->getPredicate() == FCmpInst::FCMP_ORD) {
3989 // (fcmp ord x, c) & (fcmp ord y, c) -> (fcmp ord x, y)
3990 if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
3991 if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
3992 // If either of the constants are nans, then the whole thing returns
3994 if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
3995 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
3996 return new FCmpInst(FCmpInst::FCMP_ORD,
3997 LHS->getOperand(0), RHS->getOperand(0));
4000 // Handle vector zeros. This occurs because the canonical form of
4001 // "fcmp ord x,x" is "fcmp ord x, 0".
4002 if (isa<ConstantAggregateZero>(LHS->getOperand(1)) &&
4003 isa<ConstantAggregateZero>(RHS->getOperand(1)))
4004 return new FCmpInst(FCmpInst::FCMP_ORD,
4005 LHS->getOperand(0), RHS->getOperand(0));
4009 Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1);
4010 Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1);
4011 FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate();
4014 if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
4015 // Swap RHS operands to match LHS.
4016 Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
4017 std::swap(Op1LHS, Op1RHS);
4020 if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
4021 // Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y).
4023 return new FCmpInst((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS);
4025 if (Op0CC == FCmpInst::FCMP_FALSE || Op1CC == FCmpInst::FCMP_FALSE)
4026 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
4027 if (Op0CC == FCmpInst::FCMP_TRUE)
4028 return ReplaceInstUsesWith(I, RHS);
4029 if (Op1CC == FCmpInst::FCMP_TRUE)
4030 return ReplaceInstUsesWith(I, LHS);
4034 unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
4035 unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
4037 std::swap(LHS, RHS);
4038 std::swap(Op0Pred, Op1Pred);
4039 std::swap(Op0Ordered, Op1Ordered);
4042 // uno && ueq -> uno && (uno || eq) -> ueq
4043 // ord && olt -> ord && (ord && lt) -> olt
4044 if (Op0Ordered == Op1Ordered)
4045 return ReplaceInstUsesWith(I, RHS);
4047 // uno && oeq -> uno && (ord && eq) -> false
4048 // uno && ord -> false
4050 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
4051 // ord && ueq -> ord && (uno || eq) -> oeq
4052 return cast<Instruction>(getFCmpValue(true, Op1Pred,
4053 Op0LHS, Op0RHS, Context));
4061 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
4062 bool Changed = SimplifyCommutative(I);
4063 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
4065 if (isa<UndefValue>(Op1)) // X & undef -> 0
4066 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
4070 return ReplaceInstUsesWith(I, Op1);
4072 // See if we can simplify any instructions used by the instruction whose sole
4073 // purpose is to compute bits we don't care about.
4074 if (SimplifyDemandedInstructionBits(I))
4076 if (isa<VectorType>(I.getType())) {
4077 if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) {
4078 if (CP->isAllOnesValue()) // X & <-1,-1> -> X
4079 return ReplaceInstUsesWith(I, I.getOperand(0));
4080 } else if (isa<ConstantAggregateZero>(Op1)) {
4081 return ReplaceInstUsesWith(I, Op1); // X & <0,0> -> <0,0>
4085 if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) {
4086 const APInt &AndRHSMask = AndRHS->getValue();
4087 APInt NotAndRHS(~AndRHSMask);
4089 // Optimize a variety of ((val OP C1) & C2) combinations...
4090 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
4091 Value *Op0LHS = Op0I->getOperand(0);
4092 Value *Op0RHS = Op0I->getOperand(1);
4093 switch (Op0I->getOpcode()) {
4095 case Instruction::Xor:
4096 case Instruction::Or:
4097 // If the mask is only needed on one incoming arm, push it up.
4098 if (!Op0I->hasOneUse()) break;
4100 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
4101 // Not masking anything out for the LHS, move to RHS.
4102 Value *NewRHS = Builder->CreateAnd(Op0RHS, AndRHS,
4103 Op0RHS->getName()+".masked");
4104 return BinaryOperator::Create(Op0I->getOpcode(), Op0LHS, NewRHS);
4106 if (!isa<Constant>(Op0RHS) &&
4107 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
4108 // Not masking anything out for the RHS, move to LHS.
4109 Value *NewLHS = Builder->CreateAnd(Op0LHS, AndRHS,
4110 Op0LHS->getName()+".masked");
4111 return BinaryOperator::Create(Op0I->getOpcode(), NewLHS, Op0RHS);
4115 case Instruction::Add:
4116 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
4117 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
4118 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
4119 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
4120 return BinaryOperator::CreateAnd(V, AndRHS);
4121 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
4122 return BinaryOperator::CreateAnd(V, AndRHS); // Add commutes
4125 case Instruction::Sub:
4126 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
4127 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
4128 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
4129 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
4130 return BinaryOperator::CreateAnd(V, AndRHS);
4132 // (A - N) & AndRHS -> -N & AndRHS iff A&AndRHS==0 and AndRHS
4133 // has 1's for all bits that the subtraction with A might affect.
4134 if (Op0I->hasOneUse()) {
4135 uint32_t BitWidth = AndRHSMask.getBitWidth();
4136 uint32_t Zeros = AndRHSMask.countLeadingZeros();
4137 APInt Mask = APInt::getLowBitsSet(BitWidth, BitWidth - Zeros);
4139 ConstantInt *A = dyn_cast<ConstantInt>(Op0LHS);
4140 if (!(A && A->isZero()) && // avoid infinite recursion.
4141 MaskedValueIsZero(Op0LHS, Mask)) {
4142 Value *NewNeg = Builder->CreateNeg(Op0RHS);
4143 return BinaryOperator::CreateAnd(NewNeg, AndRHS);
4148 case Instruction::Shl:
4149 case Instruction::LShr:
4150 // (1 << x) & 1 --> zext(x == 0)
4151 // (1 >> x) & 1 --> zext(x == 0)
4152 if (AndRHSMask == 1 && Op0LHS == AndRHS) {
4154 Builder->CreateICmpEQ(Op0RHS, Constant::getNullValue(I.getType()));
4155 return new ZExtInst(NewICmp, I.getType());
4160 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
4161 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
4163 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
4164 // If this is an integer truncation or change from signed-to-unsigned, and
4165 // if the source is an and/or with immediate, transform it. This
4166 // frequently occurs for bitfield accesses.
4167 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
4168 if ((isa<TruncInst>(CI) || isa<BitCastInst>(CI)) &&
4169 CastOp->getNumOperands() == 2)
4170 if (ConstantInt *AndCI = dyn_cast<ConstantInt>(CastOp->getOperand(1))) {
4171 if (CastOp->getOpcode() == Instruction::And) {
4172 // Change: and (cast (and X, C1) to T), C2
4173 // into : and (cast X to T), trunc_or_bitcast(C1)&C2
4174 // This will fold the two constants together, which may allow
4175 // other simplifications.
4176 Value *NewCast = Builder->CreateTruncOrBitCast(
4177 CastOp->getOperand(0), I.getType(),
4178 CastOp->getName()+".shrunk");
4179 // trunc_or_bitcast(C1)&C2
4180 Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
4181 C3 = ConstantExpr::getAnd(C3, AndRHS);
4182 return BinaryOperator::CreateAnd(NewCast, C3);
4183 } else if (CastOp->getOpcode() == Instruction::Or) {
4184 // Change: and (cast (or X, C1) to T), C2
4185 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
4186 Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
4187 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS)
4189 return ReplaceInstUsesWith(I, AndRHS);
4195 // Try to fold constant and into select arguments.
4196 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
4197 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
4199 if (isa<PHINode>(Op0))
4200 if (Instruction *NV = FoldOpIntoPhi(I))
4204 Value *Op0NotVal = dyn_castNotVal(Op0);
4205 Value *Op1NotVal = dyn_castNotVal(Op1);
4207 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
4208 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
4210 // (~A & ~B) == (~(A | B)) - De Morgan's Law
4211 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
4212 Value *Or = Builder->CreateOr(Op0NotVal, Op1NotVal,
4213 I.getName()+".demorgan");
4214 return BinaryOperator::CreateNot(Or);
4218 Value *A = 0, *B = 0, *C = 0, *D = 0;
4219 if (match(Op0, m_Or(m_Value(A), m_Value(B)))) {
4220 if (A == Op1 || B == Op1) // (A | ?) & A --> A
4221 return ReplaceInstUsesWith(I, Op1);
4223 // (A|B) & ~(A&B) -> A^B
4224 if (match(Op1, m_Not(m_And(m_Value(C), m_Value(D))))) {
4225 if ((A == C && B == D) || (A == D && B == C))
4226 return BinaryOperator::CreateXor(A, B);
4230 if (match(Op1, m_Or(m_Value(A), m_Value(B)))) {
4231 if (A == Op0 || B == Op0) // A & (A | ?) --> A
4232 return ReplaceInstUsesWith(I, Op0);
4234 // ~(A&B) & (A|B) -> A^B
4235 if (match(Op0, m_Not(m_And(m_Value(C), m_Value(D))))) {
4236 if ((A == C && B == D) || (A == D && B == C))
4237 return BinaryOperator::CreateXor(A, B);
4241 if (Op0->hasOneUse() &&
4242 match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
4243 if (A == Op1) { // (A^B)&A -> A&(A^B)
4244 I.swapOperands(); // Simplify below
4245 std::swap(Op0, Op1);
4246 } else if (B == Op1) { // (A^B)&B -> B&(B^A)
4247 cast<BinaryOperator>(Op0)->swapOperands();
4248 I.swapOperands(); // Simplify below
4249 std::swap(Op0, Op1);
4253 if (Op1->hasOneUse() &&
4254 match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
4255 if (B == Op0) { // B&(A^B) -> B&(B^A)
4256 cast<BinaryOperator>(Op1)->swapOperands();
4259 if (A == Op0) // A&(A^B) -> A & ~B
4260 return BinaryOperator::CreateAnd(A, Builder->CreateNot(B, "tmp"));
4263 // (A&((~A)|B)) -> A&B
4264 if (match(Op0, m_Or(m_Not(m_Specific(Op1)), m_Value(A))) ||
4265 match(Op0, m_Or(m_Value(A), m_Not(m_Specific(Op1)))))
4266 return BinaryOperator::CreateAnd(A, Op1);
4267 if (match(Op1, m_Or(m_Not(m_Specific(Op0)), m_Value(A))) ||
4268 match(Op1, m_Or(m_Value(A), m_Not(m_Specific(Op0)))))
4269 return BinaryOperator::CreateAnd(A, Op0);
4272 if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) {
4273 // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
4274 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
4277 if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0))
4278 if (Instruction *Res = FoldAndOfICmps(I, LHS, RHS))
4282 // fold (and (cast A), (cast B)) -> (cast (and A, B))
4283 if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
4284 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
4285 if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind ?
4286 const Type *SrcTy = Op0C->getOperand(0)->getType();
4287 if (SrcTy == Op1C->getOperand(0)->getType() &&
4288 SrcTy->isIntOrIntVector() &&
4289 // Only do this if the casts both really cause code to be generated.
4290 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
4292 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
4294 Value *NewOp = Builder->CreateAnd(Op0C->getOperand(0),
4295 Op1C->getOperand(0), I.getName());
4296 return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
4300 // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts.
4301 if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
4302 if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
4303 if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
4304 SI0->getOperand(1) == SI1->getOperand(1) &&
4305 (SI0->hasOneUse() || SI1->hasOneUse())) {
4307 Builder->CreateAnd(SI0->getOperand(0), SI1->getOperand(0),
4309 return BinaryOperator::Create(SI1->getOpcode(), NewOp,
4310 SI1->getOperand(1));
4314 // If and'ing two fcmp, try combine them into one.
4315 if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
4316 if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
4317 if (Instruction *Res = FoldAndOfFCmps(I, LHS, RHS))
4321 return Changed ? &I : 0;
4324 /// CollectBSwapParts - Analyze the specified subexpression and see if it is
4325 /// capable of providing pieces of a bswap. The subexpression provides pieces
4326 /// of a bswap if it is proven that each of the non-zero bytes in the output of
4327 /// the expression came from the corresponding "byte swapped" byte in some other
4328 /// value. For example, if the current subexpression is "(shl i32 %X, 24)" then
4329 /// we know that the expression deposits the low byte of %X into the high byte
4330 /// of the bswap result and that all other bytes are zero. This expression is
4331 /// accepted, the high byte of ByteValues is set to X to indicate a correct
4334 /// This function returns true if the match was unsuccessful and false if so.
4335 /// On entry to the function the "OverallLeftShift" is a signed integer value
4336 /// indicating the number of bytes that the subexpression is later shifted. For
4337 /// example, if the expression is later right shifted by 16 bits, the
4338 /// OverallLeftShift value would be -2 on entry. This is used to specify which
4339 /// byte of ByteValues is actually being set.
4341 /// Similarly, ByteMask is a bitmask where a bit is clear if its corresponding
4342 /// byte is masked to zero by a user. For example, in (X & 255), X will be
4343 /// processed with a bytemask of 1. Because bytemask is 32-bits, this limits
4344 /// this function to working on up to 32-byte (256 bit) values. ByteMask is
4345 /// always in the local (OverallLeftShift) coordinate space.
4347 static bool CollectBSwapParts(Value *V, int OverallLeftShift, uint32_t ByteMask,
4348 SmallVector<Value*, 8> &ByteValues) {
4349 if (Instruction *I = dyn_cast<Instruction>(V)) {
4350 // If this is an or instruction, it may be an inner node of the bswap.
4351 if (I->getOpcode() == Instruction::Or) {
4352 return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
4354 CollectBSwapParts(I->getOperand(1), OverallLeftShift, ByteMask,
4358 // If this is a logical shift by a constant multiple of 8, recurse with
4359 // OverallLeftShift and ByteMask adjusted.
4360 if (I->isLogicalShift() && isa<ConstantInt>(I->getOperand(1))) {
4362 cast<ConstantInt>(I->getOperand(1))->getLimitedValue(~0U);
4363 // Ensure the shift amount is defined and of a byte value.
4364 if ((ShAmt & 7) || (ShAmt > 8*ByteValues.size()))
4367 unsigned ByteShift = ShAmt >> 3;
4368 if (I->getOpcode() == Instruction::Shl) {
4369 // X << 2 -> collect(X, +2)
4370 OverallLeftShift += ByteShift;
4371 ByteMask >>= ByteShift;
4373 // X >>u 2 -> collect(X, -2)
4374 OverallLeftShift -= ByteShift;
4375 ByteMask <<= ByteShift;
4376 ByteMask &= (~0U >> (32-ByteValues.size()));
4379 if (OverallLeftShift >= (int)ByteValues.size()) return true;
4380 if (OverallLeftShift <= -(int)ByteValues.size()) return true;
4382 return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
4386 // If this is a logical 'and' with a mask that clears bytes, clear the
4387 // corresponding bytes in ByteMask.
4388 if (I->getOpcode() == Instruction::And &&
4389 isa<ConstantInt>(I->getOperand(1))) {
4390 // Scan every byte of the and mask, seeing if the byte is either 0 or 255.
4391 unsigned NumBytes = ByteValues.size();
4392 APInt Byte(I->getType()->getPrimitiveSizeInBits(), 255);
4393 const APInt &AndMask = cast<ConstantInt>(I->getOperand(1))->getValue();
4395 for (unsigned i = 0; i != NumBytes; ++i, Byte <<= 8) {
4396 // If this byte is masked out by a later operation, we don't care what
4398 if ((ByteMask & (1 << i)) == 0)
4401 // If the AndMask is all zeros for this byte, clear the bit.
4402 APInt MaskB = AndMask & Byte;
4404 ByteMask &= ~(1U << i);
4408 // If the AndMask is not all ones for this byte, it's not a bytezap.
4412 // Otherwise, this byte is kept.
4415 return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
4420 // Okay, we got to something that isn't a shift, 'or' or 'and'. This must be
4421 // the input value to the bswap. Some observations: 1) if more than one byte
4422 // is demanded from this input, then it could not be successfully assembled
4423 // into a byteswap. At least one of the two bytes would not be aligned with
4424 // their ultimate destination.
4425 if (!isPowerOf2_32(ByteMask)) return true;
4426 unsigned InputByteNo = CountTrailingZeros_32(ByteMask);
4428 // 2) The input and ultimate destinations must line up: if byte 3 of an i32
4429 // is demanded, it needs to go into byte 0 of the result. This means that the
4430 // byte needs to be shifted until it lands in the right byte bucket. The
4431 // shift amount depends on the position: if the byte is coming from the high
4432 // part of the value (e.g. byte 3) then it must be shifted right. If from the
4433 // low part, it must be shifted left.
4434 unsigned DestByteNo = InputByteNo + OverallLeftShift;
4435 if (InputByteNo < ByteValues.size()/2) {
4436 if (ByteValues.size()-1-DestByteNo != InputByteNo)
4439 if (ByteValues.size()-1-DestByteNo != InputByteNo)
4443 // If the destination byte value is already defined, the values are or'd
4444 // together, which isn't a bswap (unless it's an or of the same bits).
4445 if (ByteValues[DestByteNo] && ByteValues[DestByteNo] != V)
4447 ByteValues[DestByteNo] = V;
4451 /// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom.
4452 /// If so, insert the new bswap intrinsic and return it.
4453 Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) {
4454 const IntegerType *ITy = dyn_cast<IntegerType>(I.getType());
4455 if (!ITy || ITy->getBitWidth() % 16 ||
4456 // ByteMask only allows up to 32-byte values.
4457 ITy->getBitWidth() > 32*8)
4458 return 0; // Can only bswap pairs of bytes. Can't do vectors.
4460 /// ByteValues - For each byte of the result, we keep track of which value
4461 /// defines each byte.
4462 SmallVector<Value*, 8> ByteValues;
4463 ByteValues.resize(ITy->getBitWidth()/8);
4465 // Try to find all the pieces corresponding to the bswap.
4466 uint32_t ByteMask = ~0U >> (32-ByteValues.size());
4467 if (CollectBSwapParts(&I, 0, ByteMask, ByteValues))
4470 // Check to see if all of the bytes come from the same value.
4471 Value *V = ByteValues[0];
4472 if (V == 0) return 0; // Didn't find a byte? Must be zero.
4474 // Check to make sure that all of the bytes come from the same value.
4475 for (unsigned i = 1, e = ByteValues.size(); i != e; ++i)
4476 if (ByteValues[i] != V)
4478 const Type *Tys[] = { ITy };
4479 Module *M = I.getParent()->getParent()->getParent();
4480 Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 1);
4481 return CallInst::Create(F, V);
4484 /// MatchSelectFromAndOr - We have an expression of the form (A&C)|(B&D). Check
4485 /// If A is (cond?-1:0) and either B or D is ~(cond?-1,0) or (cond?0,-1), then
4486 /// we can simplify this expression to "cond ? C : D or B".
4487 static Instruction *MatchSelectFromAndOr(Value *A, Value *B,
4489 LLVMContext *Context) {
4490 // If A is not a select of -1/0, this cannot match.
4492 if (!match(A, m_SelectCst<-1, 0>(m_Value(Cond))))
4495 // ((cond?-1:0)&C) | (B&(cond?0:-1)) -> cond ? C : B.
4496 if (match(D, m_SelectCst<0, -1>(m_Specific(Cond))))
4497 return SelectInst::Create(Cond, C, B);
4498 if (match(D, m_Not(m_SelectCst<-1, 0>(m_Specific(Cond)))))
4499 return SelectInst::Create(Cond, C, B);
4500 // ((cond?-1:0)&C) | ((cond?0:-1)&D) -> cond ? C : D.
4501 if (match(B, m_SelectCst<0, -1>(m_Specific(Cond))))
4502 return SelectInst::Create(Cond, C, D);
4503 if (match(B, m_Not(m_SelectCst<-1, 0>(m_Specific(Cond)))))
4504 return SelectInst::Create(Cond, C, D);
4508 /// FoldOrOfICmps - Fold (icmp)|(icmp) if possible.
4509 Instruction *InstCombiner::FoldOrOfICmps(Instruction &I,
4510 ICmpInst *LHS, ICmpInst *RHS) {
4512 ConstantInt *LHSCst, *RHSCst;
4513 ICmpInst::Predicate LHSCC, RHSCC;
4515 // This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2).
4516 if (!match(LHS, m_ICmp(LHSCC, m_Value(Val),
4517 m_ConstantInt(LHSCst))) ||
4518 !match(RHS, m_ICmp(RHSCC, m_Value(Val2),
4519 m_ConstantInt(RHSCst))))
4522 // From here on, we only handle:
4523 // (icmp1 A, C1) | (icmp2 A, C2) --> something simpler.
4524 if (Val != Val2) return 0;
4526 // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
4527 if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
4528 RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
4529 LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
4530 RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
4533 // We can't fold (ugt x, C) | (sgt x, C2).
4534 if (!PredicatesFoldable(LHSCC, RHSCC))
4537 // Ensure that the larger constant is on the RHS.
4539 if (ICmpInst::isSignedPredicate(LHSCC) ||
4540 (ICmpInst::isEquality(LHSCC) &&
4541 ICmpInst::isSignedPredicate(RHSCC)))
4542 ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
4544 ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
4547 std::swap(LHS, RHS);
4548 std::swap(LHSCst, RHSCst);
4549 std::swap(LHSCC, RHSCC);
4552 // At this point, we know we have have two icmp instructions
4553 // comparing a value against two constants and or'ing the result
4554 // together. Because of the above check, we know that we only have
4555 // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
4556 // FoldICmpLogical check above), that the two constants are not
4558 assert(LHSCst != RHSCst && "Compares not folded above?");
4561 default: llvm_unreachable("Unknown integer condition code!");
4562 case ICmpInst::ICMP_EQ:
4564 default: llvm_unreachable("Unknown integer condition code!");
4565 case ICmpInst::ICMP_EQ:
4566 if (LHSCst == SubOne(RHSCst)) {
4567 // (X == 13 | X == 14) -> X-13 <u 2
4568 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
4569 Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
4570 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
4571 return new ICmpInst(ICmpInst::ICMP_ULT, Add, AddCST);
4573 break; // (X == 13 | X == 15) -> no change
4574 case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change
4575 case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change
4577 case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15
4578 case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15
4579 case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15
4580 return ReplaceInstUsesWith(I, RHS);
4583 case ICmpInst::ICMP_NE:
4585 default: llvm_unreachable("Unknown integer condition code!");
4586 case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13
4587 case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13
4588 case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13
4589 return ReplaceInstUsesWith(I, LHS);
4590 case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true
4591 case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true
4592 case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true
4593 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
4596 case ICmpInst::ICMP_ULT:
4598 default: llvm_unreachable("Unknown integer condition code!");
4599 case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
4601 case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2
4602 // If RHSCst is [us]MAXINT, it is always false. Not handling
4603 // this can cause overflow.
4604 if (RHSCst->isMaxValue(false))
4605 return ReplaceInstUsesWith(I, LHS);
4606 return InsertRangeTest(Val, LHSCst, AddOne(RHSCst),
4608 case ICmpInst::ICMP_SGT: // (X u< 13 | X s> 15) -> no change
4610 case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15
4611 case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15
4612 return ReplaceInstUsesWith(I, RHS);
4613 case ICmpInst::ICMP_SLT: // (X u< 13 | X s< 15) -> no change
4617 case ICmpInst::ICMP_SLT:
4619 default: llvm_unreachable("Unknown integer condition code!");
4620 case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change
4622 case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) s> 2
4623 // If RHSCst is [us]MAXINT, it is always false. Not handling
4624 // this can cause overflow.
4625 if (RHSCst->isMaxValue(true))
4626 return ReplaceInstUsesWith(I, LHS);
4627 return InsertRangeTest(Val, LHSCst, AddOne(RHSCst),
4629 case ICmpInst::ICMP_UGT: // (X s< 13 | X u> 15) -> no change
4631 case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15
4632 case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15
4633 return ReplaceInstUsesWith(I, RHS);
4634 case ICmpInst::ICMP_ULT: // (X s< 13 | X u< 15) -> no change
4638 case ICmpInst::ICMP_UGT:
4640 default: llvm_unreachable("Unknown integer condition code!");
4641 case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13
4642 case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13
4643 return ReplaceInstUsesWith(I, LHS);
4644 case ICmpInst::ICMP_SGT: // (X u> 13 | X s> 15) -> no change
4646 case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true
4647 case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true
4648 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
4649 case ICmpInst::ICMP_SLT: // (X u> 13 | X s< 15) -> no change
4653 case ICmpInst::ICMP_SGT:
4655 default: llvm_unreachable("Unknown integer condition code!");
4656 case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13
4657 case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13
4658 return ReplaceInstUsesWith(I, LHS);
4659 case ICmpInst::ICMP_UGT: // (X s> 13 | X u> 15) -> no change
4661 case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true
4662 case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true
4663 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
4664 case ICmpInst::ICMP_ULT: // (X s> 13 | X u< 15) -> no change
4672 Instruction *InstCombiner::FoldOrOfFCmps(Instruction &I, FCmpInst *LHS,
4674 if (LHS->getPredicate() == FCmpInst::FCMP_UNO &&
4675 RHS->getPredicate() == FCmpInst::FCMP_UNO &&
4676 LHS->getOperand(0)->getType() == RHS->getOperand(0)->getType()) {
4677 if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
4678 if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
4679 // If either of the constants are nans, then the whole thing returns
4681 if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
4682 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
4684 // Otherwise, no need to compare the two constants, compare the
4686 return new FCmpInst(FCmpInst::FCMP_UNO,
4687 LHS->getOperand(0), RHS->getOperand(0));
4690 // Handle vector zeros. This occurs because the canonical form of
4691 // "fcmp uno x,x" is "fcmp uno x, 0".
4692 if (isa<ConstantAggregateZero>(LHS->getOperand(1)) &&
4693 isa<ConstantAggregateZero>(RHS->getOperand(1)))
4694 return new FCmpInst(FCmpInst::FCMP_UNO,
4695 LHS->getOperand(0), RHS->getOperand(0));
4700 Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1);
4701 Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1);
4702 FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate();
4704 if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
4705 // Swap RHS operands to match LHS.
4706 Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
4707 std::swap(Op1LHS, Op1RHS);
4709 if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
4710 // Simplify (fcmp cc0 x, y) | (fcmp cc1 x, y).
4712 return new FCmpInst((FCmpInst::Predicate)Op0CC,
4714 if (Op0CC == FCmpInst::FCMP_TRUE || Op1CC == FCmpInst::FCMP_TRUE)
4715 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
4716 if (Op0CC == FCmpInst::FCMP_FALSE)
4717 return ReplaceInstUsesWith(I, RHS);
4718 if (Op1CC == FCmpInst::FCMP_FALSE)
4719 return ReplaceInstUsesWith(I, LHS);
4722 unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
4723 unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
4724 if (Op0Ordered == Op1Ordered) {
4725 // If both are ordered or unordered, return a new fcmp with
4726 // or'ed predicates.
4727 Value *RV = getFCmpValue(Op0Ordered, Op0Pred|Op1Pred,
4728 Op0LHS, Op0RHS, Context);
4729 if (Instruction *I = dyn_cast<Instruction>(RV))
4731 // Otherwise, it's a constant boolean value...
4732 return ReplaceInstUsesWith(I, RV);
4738 /// FoldOrWithConstants - This helper function folds:
4740 /// ((A | B) & C1) | (B & C2)
4746 /// when the XOR of the two constants is "all ones" (-1).
4747 Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I, Value *Op,
4748 Value *A, Value *B, Value *C) {
4749 ConstantInt *CI1 = dyn_cast<ConstantInt>(C);
4753 ConstantInt *CI2 = 0;
4754 if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2)))) return 0;
4756 APInt Xor = CI1->getValue() ^ CI2->getValue();
4757 if (!Xor.isAllOnesValue()) return 0;
4759 if (V1 == A || V1 == B) {
4760 Value *NewOp = Builder->CreateAnd((V1 == A) ? B : A, CI1);
4761 return BinaryOperator::CreateOr(NewOp, V1);
4767 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
4768 bool Changed = SimplifyCommutative(I);
4769 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
4771 if (isa<UndefValue>(Op1)) // X | undef -> -1
4772 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
4776 return ReplaceInstUsesWith(I, Op0);
4778 // See if we can simplify any instructions used by the instruction whose sole
4779 // purpose is to compute bits we don't care about.
4780 if (SimplifyDemandedInstructionBits(I))
4782 if (isa<VectorType>(I.getType())) {
4783 if (isa<ConstantAggregateZero>(Op1)) {
4784 return ReplaceInstUsesWith(I, Op0); // X | <0,0> -> X
4785 } else if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) {
4786 if (CP->isAllOnesValue()) // X | <-1,-1> -> <-1,-1>
4787 return ReplaceInstUsesWith(I, I.getOperand(1));
4792 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
4793 ConstantInt *C1 = 0; Value *X = 0;
4794 // (X & C1) | C2 --> (X | C2) & (C1|C2)
4795 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) &&
4797 Value *Or = Builder->CreateOr(X, RHS);
4799 return BinaryOperator::CreateAnd(Or,
4800 ConstantInt::get(*Context, RHS->getValue() | C1->getValue()));
4803 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
4804 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) &&
4806 Value *Or = Builder->CreateOr(X, RHS);
4808 return BinaryOperator::CreateXor(Or,
4809 ConstantInt::get(*Context, C1->getValue() & ~RHS->getValue()));
4812 // Try to fold constant and into select arguments.
4813 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
4814 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
4816 if (isa<PHINode>(Op0))
4817 if (Instruction *NV = FoldOpIntoPhi(I))
4821 Value *A = 0, *B = 0;
4822 ConstantInt *C1 = 0, *C2 = 0;
4824 if (match(Op0, m_And(m_Value(A), m_Value(B))))
4825 if (A == Op1 || B == Op1) // (A & ?) | A --> A
4826 return ReplaceInstUsesWith(I, Op1);
4827 if (match(Op1, m_And(m_Value(A), m_Value(B))))
4828 if (A == Op0 || B == Op0) // A | (A & ?) --> A
4829 return ReplaceInstUsesWith(I, Op0);
4831 // (A | B) | C and A | (B | C) -> bswap if possible.
4832 // (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible.
4833 if (match(Op0, m_Or(m_Value(), m_Value())) ||
4834 match(Op1, m_Or(m_Value(), m_Value())) ||
4835 (match(Op0, m_Shift(m_Value(), m_Value())) &&
4836 match(Op1, m_Shift(m_Value(), m_Value())))) {
4837 if (Instruction *BSwap = MatchBSwap(I))
4841 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
4842 if (Op0->hasOneUse() &&
4843 match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
4844 MaskedValueIsZero(Op1, C1->getValue())) {
4845 Value *NOr = Builder->CreateOr(A, Op1);
4847 return BinaryOperator::CreateXor(NOr, C1);
4850 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
4851 if (Op1->hasOneUse() &&
4852 match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
4853 MaskedValueIsZero(Op0, C1->getValue())) {
4854 Value *NOr = Builder->CreateOr(A, Op0);
4856 return BinaryOperator::CreateXor(NOr, C1);
4860 Value *C = 0, *D = 0;
4861 if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
4862 match(Op1, m_And(m_Value(B), m_Value(D)))) {
4863 Value *V1 = 0, *V2 = 0, *V3 = 0;
4864 C1 = dyn_cast<ConstantInt>(C);
4865 C2 = dyn_cast<ConstantInt>(D);
4866 if (C1 && C2) { // (A & C1)|(B & C2)
4867 // If we have: ((V + N) & C1) | (V & C2)
4868 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
4869 // replace with V+N.
4870 if (C1->getValue() == ~C2->getValue()) {
4871 if ((C2->getValue() & (C2->getValue()+1)) == 0 && // C2 == 0+1+
4872 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
4873 // Add commutes, try both ways.
4874 if (V1 == B && MaskedValueIsZero(V2, C2->getValue()))
4875 return ReplaceInstUsesWith(I, A);
4876 if (V2 == B && MaskedValueIsZero(V1, C2->getValue()))
4877 return ReplaceInstUsesWith(I, A);
4879 // Or commutes, try both ways.
4880 if ((C1->getValue() & (C1->getValue()+1)) == 0 &&
4881 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
4882 // Add commutes, try both ways.
4883 if (V1 == A && MaskedValueIsZero(V2, C1->getValue()))
4884 return ReplaceInstUsesWith(I, B);
4885 if (V2 == A && MaskedValueIsZero(V1, C1->getValue()))
4886 return ReplaceInstUsesWith(I, B);
4889 V1 = 0; V2 = 0; V3 = 0;
4892 // Check to see if we have any common things being and'ed. If so, find the
4893 // terms for V1 & (V2|V3).
4894 if (isOnlyUse(Op0) || isOnlyUse(Op1)) {
4895 if (A == B) // (A & C)|(A & D) == A & (C|D)
4896 V1 = A, V2 = C, V3 = D;
4897 else if (A == D) // (A & C)|(B & A) == A & (B|C)
4898 V1 = A, V2 = B, V3 = C;
4899 else if (C == B) // (A & C)|(C & D) == C & (A|D)
4900 V1 = C, V2 = A, V3 = D;
4901 else if (C == D) // (A & C)|(B & C) == C & (A|B)
4902 V1 = C, V2 = A, V3 = B;
4905 Value *Or = Builder->CreateOr(V2, V3, "tmp");
4906 return BinaryOperator::CreateAnd(V1, Or);
4910 // (A & (C0?-1:0)) | (B & ~(C0?-1:0)) -> C0 ? A : B, and commuted variants
4911 if (Instruction *Match = MatchSelectFromAndOr(A, B, C, D, Context))
4913 if (Instruction *Match = MatchSelectFromAndOr(B, A, D, C, Context))
4915 if (Instruction *Match = MatchSelectFromAndOr(C, B, A, D, Context))
4917 if (Instruction *Match = MatchSelectFromAndOr(D, A, B, C, Context))
4920 // ((A&~B)|(~A&B)) -> A^B
4921 if ((match(C, m_Not(m_Specific(D))) &&
4922 match(B, m_Not(m_Specific(A)))))
4923 return BinaryOperator::CreateXor(A, D);
4924 // ((~B&A)|(~A&B)) -> A^B
4925 if ((match(A, m_Not(m_Specific(D))) &&
4926 match(B, m_Not(m_Specific(C)))))
4927 return BinaryOperator::CreateXor(C, D);
4928 // ((A&~B)|(B&~A)) -> A^B
4929 if ((match(C, m_Not(m_Specific(B))) &&
4930 match(D, m_Not(m_Specific(A)))))
4931 return BinaryOperator::CreateXor(A, B);
4932 // ((~B&A)|(B&~A)) -> A^B
4933 if ((match(A, m_Not(m_Specific(B))) &&
4934 match(D, m_Not(m_Specific(C)))))
4935 return BinaryOperator::CreateXor(C, B);
4938 // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
4939 if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
4940 if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
4941 if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
4942 SI0->getOperand(1) == SI1->getOperand(1) &&
4943 (SI0->hasOneUse() || SI1->hasOneUse())) {
4944 Value *NewOp = Builder->CreateOr(SI0->getOperand(0), SI1->getOperand(0),
4946 return BinaryOperator::Create(SI1->getOpcode(), NewOp,
4947 SI1->getOperand(1));
4951 // ((A|B)&1)|(B&-2) -> (A&1) | B
4952 if (match(Op0, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
4953 match(Op0, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
4954 Instruction *Ret = FoldOrWithConstants(I, Op1, A, B, C);
4955 if (Ret) return Ret;
4957 // (B&-2)|((A|B)&1) -> (A&1) | B
4958 if (match(Op1, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
4959 match(Op1, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
4960 Instruction *Ret = FoldOrWithConstants(I, Op0, A, B, C);
4961 if (Ret) return Ret;
4964 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
4965 if (A == Op1) // ~A | A == -1
4966 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
4970 // Note, A is still live here!
4971 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
4973 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
4975 // (~A | ~B) == (~(A & B)) - De Morgan's Law
4976 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
4977 Value *And = Builder->CreateAnd(A, B, I.getName()+".demorgan");
4978 return BinaryOperator::CreateNot(And);
4982 // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
4983 if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) {
4984 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
4987 if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0)))
4988 if (Instruction *Res = FoldOrOfICmps(I, LHS, RHS))
4992 // fold (or (cast A), (cast B)) -> (cast (or A, B))
4993 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
4994 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
4995 if (Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ?
4996 if (!isa<ICmpInst>(Op0C->getOperand(0)) ||
4997 !isa<ICmpInst>(Op1C->getOperand(0))) {
4998 const Type *SrcTy = Op0C->getOperand(0)->getType();
4999 if (SrcTy == Op1C->getOperand(0)->getType() &&
5000 SrcTy->isIntOrIntVector() &&
5001 // Only do this if the casts both really cause code to be
5003 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
5005 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
5007 Value *NewOp = Builder->CreateOr(Op0C->getOperand(0),
5008 Op1C->getOperand(0), I.getName());
5009 return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
5016 // (fcmp uno x, c) | (fcmp uno y, c) -> (fcmp uno x, y)
5017 if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
5018 if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
5019 if (Instruction *Res = FoldOrOfFCmps(I, LHS, RHS))
5023 return Changed ? &I : 0;
5028 // XorSelf - Implements: X ^ X --> 0
5031 XorSelf(Value *rhs) : RHS(rhs) {}
5032 bool shouldApply(Value *LHS) const { return LHS == RHS; }
5033 Instruction *apply(BinaryOperator &Xor) const {
5040 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
5041 bool Changed = SimplifyCommutative(I);
5042 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
5044 if (isa<UndefValue>(Op1)) {
5045 if (isa<UndefValue>(Op0))
5046 // Handle undef ^ undef -> 0 special case. This is a common
5048 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
5049 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
5052 // xor X, X = 0, even if X is nested in a sequence of Xor's.
5053 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
5054 assert(Result == &I && "AssociativeOpt didn't work?"); Result=Result;
5055 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
5058 // See if we can simplify any instructions used by the instruction whose sole
5059 // purpose is to compute bits we don't care about.
5060 if (SimplifyDemandedInstructionBits(I))
5062 if (isa<VectorType>(I.getType()))
5063 if (isa<ConstantAggregateZero>(Op1))
5064 return ReplaceInstUsesWith(I, Op0); // X ^ <0,0> -> X
5066 // Is this a ~ operation?
5067 if (Value *NotOp = dyn_castNotVal(&I)) {
5068 // ~(~X & Y) --> (X | ~Y) - De Morgan's Law
5069 // ~(~X | Y) === (X & ~Y) - De Morgan's Law
5070 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(NotOp)) {
5071 if (Op0I->getOpcode() == Instruction::And ||
5072 Op0I->getOpcode() == Instruction::Or) {
5073 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
5074 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
5076 Builder->CreateNot(Op0I->getOperand(1),
5077 Op0I->getOperand(1)->getName()+".not");
5078 if (Op0I->getOpcode() == Instruction::And)
5079 return BinaryOperator::CreateOr(Op0NotVal, NotY);
5080 return BinaryOperator::CreateAnd(Op0NotVal, NotY);
5087 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
5088 if (RHS->isOne() && Op0->hasOneUse()) {
5089 // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B
5090 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0))
5091 return new ICmpInst(ICI->getInversePredicate(),
5092 ICI->getOperand(0), ICI->getOperand(1));
5094 if (FCmpInst *FCI = dyn_cast<FCmpInst>(Op0))
5095 return new FCmpInst(FCI->getInversePredicate(),
5096 FCI->getOperand(0), FCI->getOperand(1));
5099 // fold (xor(zext(cmp)), 1) and (xor(sext(cmp)), -1) to ext(!cmp).
5100 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
5101 if (CmpInst *CI = dyn_cast<CmpInst>(Op0C->getOperand(0))) {
5102 if (CI->hasOneUse() && Op0C->hasOneUse()) {
5103 Instruction::CastOps Opcode = Op0C->getOpcode();
5104 if ((Opcode == Instruction::ZExt || Opcode == Instruction::SExt) &&
5105 (RHS == ConstantExpr::getCast(Opcode,
5106 ConstantInt::getTrue(*Context),
5107 Op0C->getDestTy()))) {
5108 CI->setPredicate(CI->getInversePredicate());
5109 return CastInst::Create(Opcode, CI, Op0C->getType());
5115 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
5116 // ~(c-X) == X-c-1 == X+(-c-1)
5117 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
5118 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
5119 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
5120 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
5121 ConstantInt::get(I.getType(), 1));
5122 return BinaryOperator::CreateAdd(Op0I->getOperand(1), ConstantRHS);
5125 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
5126 if (Op0I->getOpcode() == Instruction::Add) {
5127 // ~(X-c) --> (-c-1)-X
5128 if (RHS->isAllOnesValue()) {
5129 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
5130 return BinaryOperator::CreateSub(
5131 ConstantExpr::getSub(NegOp0CI,
5132 ConstantInt::get(I.getType(), 1)),
5133 Op0I->getOperand(0));
5134 } else if (RHS->getValue().isSignBit()) {
5135 // (X + C) ^ signbit -> (X + C + signbit)
5136 Constant *C = ConstantInt::get(*Context,
5137 RHS->getValue() + Op0CI->getValue());
5138 return BinaryOperator::CreateAdd(Op0I->getOperand(0), C);
5141 } else if (Op0I->getOpcode() == Instruction::Or) {
5142 // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
5143 if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue())) {
5144 Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS);
5145 // Anything in both C1 and C2 is known to be zero, remove it from
5147 Constant *CommonBits = ConstantExpr::getAnd(Op0CI, RHS);
5148 NewRHS = ConstantExpr::getAnd(NewRHS,
5149 ConstantExpr::getNot(CommonBits));
5151 I.setOperand(0, Op0I->getOperand(0));
5152 I.setOperand(1, NewRHS);
5159 // Try to fold constant and into select arguments.
5160 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
5161 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
5163 if (isa<PHINode>(Op0))
5164 if (Instruction *NV = FoldOpIntoPhi(I))
5168 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
5170 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
5172 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
5174 return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
5177 BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
5180 if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
5181 if (A == Op0) { // B^(B|A) == (A|B)^B
5182 Op1I->swapOperands();
5184 std::swap(Op0, Op1);
5185 } else if (B == Op0) { // B^(A|B) == (A|B)^B
5186 I.swapOperands(); // Simplified below.
5187 std::swap(Op0, Op1);
5189 } else if (match(Op1I, m_Xor(m_Specific(Op0), m_Value(B)))) {
5190 return ReplaceInstUsesWith(I, B); // A^(A^B) == B
5191 } else if (match(Op1I, m_Xor(m_Value(A), m_Specific(Op0)))) {
5192 return ReplaceInstUsesWith(I, A); // A^(B^A) == B
5193 } else if (match(Op1I, m_And(m_Value(A), m_Value(B))) &&
5195 if (A == Op0) { // A^(A&B) -> A^(B&A)
5196 Op1I->swapOperands();
5199 if (B == Op0) { // A^(B&A) -> (B&A)^A
5200 I.swapOperands(); // Simplified below.
5201 std::swap(Op0, Op1);
5206 BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0);
5209 if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
5210 Op0I->hasOneUse()) {
5211 if (A == Op1) // (B|A)^B == (A|B)^B
5213 if (B == Op1) // (A|B)^B == A & ~B
5214 return BinaryOperator::CreateAnd(A, Builder->CreateNot(Op1, "tmp"));
5215 } else if (match(Op0I, m_Xor(m_Specific(Op1), m_Value(B)))) {
5216 return ReplaceInstUsesWith(I, B); // (A^B)^A == B
5217 } else if (match(Op0I, m_Xor(m_Value(A), m_Specific(Op1)))) {
5218 return ReplaceInstUsesWith(I, A); // (B^A)^A == B
5219 } else if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
5221 if (A == Op1) // (A&B)^A -> (B&A)^A
5223 if (B == Op1 && // (B&A)^A == ~B & A
5224 !isa<ConstantInt>(Op1)) { // Canonical form is (B&C)^C
5225 return BinaryOperator::CreateAnd(Builder->CreateNot(A, "tmp"), Op1);
5230 // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts.
5231 if (Op0I && Op1I && Op0I->isShift() &&
5232 Op0I->getOpcode() == Op1I->getOpcode() &&
5233 Op0I->getOperand(1) == Op1I->getOperand(1) &&
5234 (Op1I->hasOneUse() || Op1I->hasOneUse())) {
5236 Builder->CreateXor(Op0I->getOperand(0), Op1I->getOperand(0),
5238 return BinaryOperator::Create(Op1I->getOpcode(), NewOp,
5239 Op1I->getOperand(1));
5243 Value *A, *B, *C, *D;
5244 // (A & B)^(A | B) -> A ^ B
5245 if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
5246 match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
5247 if ((A == C && B == D) || (A == D && B == C))
5248 return BinaryOperator::CreateXor(A, B);
5250 // (A | B)^(A & B) -> A ^ B
5251 if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
5252 match(Op1I, m_And(m_Value(C), m_Value(D)))) {
5253 if ((A == C && B == D) || (A == D && B == C))
5254 return BinaryOperator::CreateXor(A, B);
5258 if ((Op0I->hasOneUse() || Op1I->hasOneUse()) &&
5259 match(Op0I, m_And(m_Value(A), m_Value(B))) &&
5260 match(Op1I, m_And(m_Value(C), m_Value(D)))) {
5261 // (X & Y)^(X & Y) -> (Y^Z) & X
5262 Value *X = 0, *Y = 0, *Z = 0;
5264 X = A, Y = B, Z = D;
5266 X = A, Y = B, Z = C;
5268 X = B, Y = A, Z = D;
5270 X = B, Y = A, Z = C;
5273 Value *NewOp = Builder->CreateXor(Y, Z, Op0->getName());
5274 return BinaryOperator::CreateAnd(NewOp, X);
5279 // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
5280 if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
5281 if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
5284 // fold (xor (cast A), (cast B)) -> (cast (xor A, B))
5285 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
5286 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
5287 if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind?
5288 const Type *SrcTy = Op0C->getOperand(0)->getType();
5289 if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
5290 // Only do this if the casts both really cause code to be generated.
5291 ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
5293 ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
5295 Value *NewOp = Builder->CreateXor(Op0C->getOperand(0),
5296 Op1C->getOperand(0), I.getName());
5297 return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
5302 return Changed ? &I : 0;
5305 static ConstantInt *ExtractElement(Constant *V, Constant *Idx,
5306 LLVMContext *Context) {
5307 return cast<ConstantInt>(ConstantExpr::getExtractElement(V, Idx));
5310 static bool HasAddOverflow(ConstantInt *Result,
5311 ConstantInt *In1, ConstantInt *In2,
5314 if (In2->getValue().isNegative())
5315 return Result->getValue().sgt(In1->getValue());
5317 return Result->getValue().slt(In1->getValue());
5319 return Result->getValue().ult(In1->getValue());
5322 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
5323 /// overflowed for this type.
5324 static bool AddWithOverflow(Constant *&Result, Constant *In1,
5325 Constant *In2, LLVMContext *Context,
5326 bool IsSigned = false) {
5327 Result = ConstantExpr::getAdd(In1, In2);
5329 if (const VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
5330 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
5331 Constant *Idx = ConstantInt::get(Type::getInt32Ty(*Context), i);
5332 if (HasAddOverflow(ExtractElement(Result, Idx, Context),
5333 ExtractElement(In1, Idx, Context),
5334 ExtractElement(In2, Idx, Context),
5341 return HasAddOverflow(cast<ConstantInt>(Result),
5342 cast<ConstantInt>(In1), cast<ConstantInt>(In2),
5346 static bool HasSubOverflow(ConstantInt *Result,
5347 ConstantInt *In1, ConstantInt *In2,
5350 if (In2->getValue().isNegative())
5351 return Result->getValue().slt(In1->getValue());
5353 return Result->getValue().sgt(In1->getValue());
5355 return Result->getValue().ugt(In1->getValue());
5358 /// SubWithOverflow - Compute Result = In1-In2, returning true if the result
5359 /// overflowed for this type.
5360 static bool SubWithOverflow(Constant *&Result, Constant *In1,
5361 Constant *In2, LLVMContext *Context,
5362 bool IsSigned = false) {
5363 Result = ConstantExpr::getSub(In1, In2);
5365 if (const VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
5366 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
5367 Constant *Idx = ConstantInt::get(Type::getInt32Ty(*Context), i);
5368 if (HasSubOverflow(ExtractElement(Result, Idx, Context),
5369 ExtractElement(In1, Idx, Context),
5370 ExtractElement(In2, Idx, Context),
5377 return HasSubOverflow(cast<ConstantInt>(Result),
5378 cast<ConstantInt>(In1), cast<ConstantInt>(In2),
5382 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
5383 /// code necessary to compute the offset from the base pointer (without adding
5384 /// in the base pointer). Return the result as a signed integer of intptr size.
5385 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
5386 TargetData &TD = *IC.getTargetData();
5387 gep_type_iterator GTI = gep_type_begin(GEP);
5388 const Type *IntPtrTy = TD.getIntPtrType(I.getContext());
5389 Value *Result = Constant::getNullValue(IntPtrTy);
5391 // Build a mask for high order bits.
5392 unsigned IntPtrWidth = TD.getPointerSizeInBits();
5393 uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
5395 for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e;
5398 uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()) & PtrSizeMask;
5399 if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) {
5400 if (OpC->isZero()) continue;
5402 // Handle a struct index, which adds its field offset to the pointer.
5403 if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
5404 Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
5406 Result = IC.Builder->CreateAdd(Result,
5407 ConstantInt::get(IntPtrTy, Size),
5408 GEP->getName()+".offs");
5412 Constant *Scale = ConstantInt::get(IntPtrTy, Size);
5414 ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
5415 Scale = ConstantExpr::getMul(OC, Scale);
5416 // Emit an add instruction.
5417 Result = IC.Builder->CreateAdd(Result, Scale, GEP->getName()+".offs");
5420 // Convert to correct type.
5421 if (Op->getType() != IntPtrTy)
5422 Op = IC.Builder->CreateIntCast(Op, IntPtrTy, true, Op->getName()+".c");
5424 Constant *Scale = ConstantInt::get(IntPtrTy, Size);
5425 // We'll let instcombine(mul) convert this to a shl if possible.
5426 Op = IC.Builder->CreateMul(Op, Scale, GEP->getName()+".idx");
5429 // Emit an add instruction.
5430 Result = IC.Builder->CreateAdd(Op, Result, GEP->getName()+".offs");
5436 /// EvaluateGEPOffsetExpression - Return a value that can be used to compare
5437 /// the *offset* implied by a GEP to zero. For example, if we have &A[i], we
5438 /// want to return 'i' for "icmp ne i, 0". Note that, in general, indices can
5439 /// be complex, and scales are involved. The above expression would also be
5440 /// legal to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32).
5441 /// This later form is less amenable to optimization though, and we are allowed
5442 /// to generate the first by knowing that pointer arithmetic doesn't overflow.
5444 /// If we can't emit an optimized form for this expression, this returns null.
5446 static Value *EvaluateGEPOffsetExpression(User *GEP, Instruction &I,
5448 TargetData &TD = *IC.getTargetData();
5449 gep_type_iterator GTI = gep_type_begin(GEP);
5451 // Check to see if this gep only has a single variable index. If so, and if
5452 // any constant indices are a multiple of its scale, then we can compute this
5453 // in terms of the scale of the variable index. For example, if the GEP
5454 // implies an offset of "12 + i*4", then we can codegen this as "3 + i",
5455 // because the expression will cross zero at the same point.
5456 unsigned i, e = GEP->getNumOperands();
5458 for (i = 1; i != e; ++i, ++GTI) {
5459 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
5460 // Compute the aggregate offset of constant indices.
5461 if (CI->isZero()) continue;
5463 // Handle a struct index, which adds its field offset to the pointer.
5464 if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
5465 Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
5467 uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
5468 Offset += Size*CI->getSExtValue();
5471 // Found our variable index.
5476 // If there are no variable indices, we must have a constant offset, just
5477 // evaluate it the general way.
5478 if (i == e) return 0;
5480 Value *VariableIdx = GEP->getOperand(i);
5481 // Determine the scale factor of the variable element. For example, this is
5482 // 4 if the variable index is into an array of i32.
5483 uint64_t VariableScale = TD.getTypeAllocSize(GTI.getIndexedType());
5485 // Verify that there are no other variable indices. If so, emit the hard way.
5486 for (++i, ++GTI; i != e; ++i, ++GTI) {
5487 ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i));
5490 // Compute the aggregate offset of constant indices.
5491 if (CI->isZero()) continue;
5493 // Handle a struct index, which adds its field offset to the pointer.
5494 if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
5495 Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
5497 uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
5498 Offset += Size*CI->getSExtValue();
5502 // Okay, we know we have a single variable index, which must be a
5503 // pointer/array/vector index. If there is no offset, life is simple, return
5505 unsigned IntPtrWidth = TD.getPointerSizeInBits();
5507 // Cast to intptrty in case a truncation occurs. If an extension is needed,
5508 // we don't need to bother extending: the extension won't affect where the
5509 // computation crosses zero.
5510 if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth)
5511 VariableIdx = new TruncInst(VariableIdx,
5512 TD.getIntPtrType(VariableIdx->getContext()),
5513 VariableIdx->getName(), &I);
5517 // Otherwise, there is an index. The computation we will do will be modulo
5518 // the pointer size, so get it.
5519 uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
5521 Offset &= PtrSizeMask;
5522 VariableScale &= PtrSizeMask;
5524 // To do this transformation, any constant index must be a multiple of the
5525 // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i",
5526 // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a
5527 // multiple of the variable scale.
5528 int64_t NewOffs = Offset / (int64_t)VariableScale;
5529 if (Offset != NewOffs*(int64_t)VariableScale)
5532 // Okay, we can do this evaluation. Start by converting the index to intptr.
5533 const Type *IntPtrTy = TD.getIntPtrType(VariableIdx->getContext());
5534 if (VariableIdx->getType() != IntPtrTy)
5535 VariableIdx = CastInst::CreateIntegerCast(VariableIdx, IntPtrTy,
5537 VariableIdx->getName(), &I);
5538 Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs);
5539 return BinaryOperator::CreateAdd(VariableIdx, OffsetVal, "offset", &I);
5543 /// FoldGEPICmp - Fold comparisons between a GEP instruction and something
5544 /// else. At this point we know that the GEP is on the LHS of the comparison.
5545 Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
5546 ICmpInst::Predicate Cond,
5548 // Look through bitcasts.
5549 if (BitCastInst *BCI = dyn_cast<BitCastInst>(RHS))
5550 RHS = BCI->getOperand(0);
5552 Value *PtrBase = GEPLHS->getOperand(0);
5553 if (TD && PtrBase == RHS && GEPLHS->isInBounds()) {
5554 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
5555 // This transformation (ignoring the base and scales) is valid because we
5556 // know pointers can't overflow since the gep is inbounds. See if we can
5557 // output an optimized form.
5558 Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, I, *this);
5560 // If not, synthesize the offset the hard way.
5562 Offset = EmitGEPOffset(GEPLHS, I, *this);
5563 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
5564 Constant::getNullValue(Offset->getType()));
5565 } else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) {
5566 // If the base pointers are different, but the indices are the same, just
5567 // compare the base pointer.
5568 if (PtrBase != GEPRHS->getOperand(0)) {
5569 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
5570 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
5571 GEPRHS->getOperand(0)->getType();
5573 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
5574 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
5575 IndicesTheSame = false;
5579 // If all indices are the same, just compare the base pointers.
5581 return new ICmpInst(ICmpInst::getSignedPredicate(Cond),
5582 GEPLHS->getOperand(0), GEPRHS->getOperand(0));
5584 // Otherwise, the base pointers are different and the indices are
5585 // different, bail out.
5589 // If one of the GEPs has all zero indices, recurse.
5590 bool AllZeros = true;
5591 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
5592 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
5593 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
5598 return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
5599 ICmpInst::getSwappedPredicate(Cond), I);
5601 // If the other GEP has all zero indices, recurse.
5603 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
5604 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
5605 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
5610 return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
5612 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
5613 // If the GEPs only differ by one index, compare it.
5614 unsigned NumDifferences = 0; // Keep track of # differences.
5615 unsigned DiffOperand = 0; // The operand that differs.
5616 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
5617 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
5618 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
5619 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
5620 // Irreconcilable differences.
5624 if (NumDifferences++) break;
5629 if (NumDifferences == 0) // SAME GEP?
5630 return ReplaceInstUsesWith(I, // No comparison is needed here.
5631 ConstantInt::get(Type::getInt1Ty(*Context),
5632 ICmpInst::isTrueWhenEqual(Cond)));
5634 else if (NumDifferences == 1) {
5635 Value *LHSV = GEPLHS->getOperand(DiffOperand);
5636 Value *RHSV = GEPRHS->getOperand(DiffOperand);
5637 // Make sure we do a signed comparison here.
5638 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
5642 // Only lower this if the icmp is the only user of the GEP or if we expect
5643 // the result to fold to a constant!
5645 (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
5646 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
5647 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
5648 Value *L = EmitGEPOffset(GEPLHS, I, *this);
5649 Value *R = EmitGEPOffset(GEPRHS, I, *this);
5650 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
5656 /// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible.
5658 Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I,
5661 if (!isa<ConstantFP>(RHSC)) return 0;
5662 const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF();
5664 // Get the width of the mantissa. We don't want to hack on conversions that
5665 // might lose information from the integer, e.g. "i64 -> float"
5666 int MantissaWidth = LHSI->getType()->getFPMantissaWidth();
5667 if (MantissaWidth == -1) return 0; // Unknown.
5669 // Check to see that the input is converted from an integer type that is small
5670 // enough that preserves all bits. TODO: check here for "known" sign bits.
5671 // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e.
5672 unsigned InputSize = LHSI->getOperand(0)->getType()->getScalarSizeInBits();
5674 // If this is a uitofp instruction, we need an extra bit to hold the sign.
5675 bool LHSUnsigned = isa<UIToFPInst>(LHSI);
5679 // If the conversion would lose info, don't hack on this.
5680 if ((int)InputSize > MantissaWidth)
5683 // Otherwise, we can potentially simplify the comparison. We know that it
5684 // will always come through as an integer value and we know the constant is
5685 // not a NAN (it would have been previously simplified).
5686 assert(!RHS.isNaN() && "NaN comparison not already folded!");
5688 ICmpInst::Predicate Pred;
5689 switch (I.getPredicate()) {
5690 default: llvm_unreachable("Unexpected predicate!");
5691 case FCmpInst::FCMP_UEQ:
5692 case FCmpInst::FCMP_OEQ:
5693 Pred = ICmpInst::ICMP_EQ;
5695 case FCmpInst::FCMP_UGT:
5696 case FCmpInst::FCMP_OGT:
5697 Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT;
5699 case FCmpInst::FCMP_UGE:
5700 case FCmpInst::FCMP_OGE:
5701 Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE;
5703 case FCmpInst::FCMP_ULT:
5704 case FCmpInst::FCMP_OLT:
5705 Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT;
5707 case FCmpInst::FCMP_ULE:
5708 case FCmpInst::FCMP_OLE:
5709 Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE;
5711 case FCmpInst::FCMP_UNE:
5712 case FCmpInst::FCMP_ONE:
5713 Pred = ICmpInst::ICMP_NE;
5715 case FCmpInst::FCMP_ORD:
5716 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
5717 case FCmpInst::FCMP_UNO:
5718 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
5721 const IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType());
5723 // Now we know that the APFloat is a normal number, zero or inf.
5725 // See if the FP constant is too large for the integer. For example,
5726 // comparing an i8 to 300.0.
5727 unsigned IntWidth = IntTy->getScalarSizeInBits();
5730 // If the RHS value is > SignedMax, fold the comparison. This handles +INF
5731 // and large values.
5732 APFloat SMax(RHS.getSemantics(), APFloat::fcZero, false);
5733 SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true,
5734 APFloat::rmNearestTiesToEven);
5735 if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0
5736 if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT ||
5737 Pred == ICmpInst::ICMP_SLE)
5738 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
5739 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
5742 // If the RHS value is > UnsignedMax, fold the comparison. This handles
5743 // +INF and large values.
5744 APFloat UMax(RHS.getSemantics(), APFloat::fcZero, false);
5745 UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false,
5746 APFloat::rmNearestTiesToEven);
5747 if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0
5748 if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT ||
5749 Pred == ICmpInst::ICMP_ULE)
5750 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
5751 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
5756 // See if the RHS value is < SignedMin.
5757 APFloat SMin(RHS.getSemantics(), APFloat::fcZero, false);
5758 SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true,
5759 APFloat::rmNearestTiesToEven);
5760 if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0
5761 if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT ||
5762 Pred == ICmpInst::ICMP_SGE)
5763 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
5764 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
5768 // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or
5769 // [0, UMAX], but it may still be fractional. See if it is fractional by
5770 // casting the FP value to the integer value and back, checking for equality.
5771 // Don't do this for zero, because -0.0 is not fractional.
5772 Constant *RHSInt = LHSUnsigned
5773 ? ConstantExpr::getFPToUI(RHSC, IntTy)
5774 : ConstantExpr::getFPToSI(RHSC, IntTy);
5775 if (!RHS.isZero()) {
5776 bool Equal = LHSUnsigned
5777 ? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC
5778 : ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC;
5780 // If we had a comparison against a fractional value, we have to adjust
5781 // the compare predicate and sometimes the value. RHSC is rounded towards
5782 // zero at this point.
5784 default: llvm_unreachable("Unexpected integer comparison!");
5785 case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true
5786 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
5787 case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false
5788 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
5789 case ICmpInst::ICMP_ULE:
5790 // (float)int <= 4.4 --> int <= 4
5791 // (float)int <= -4.4 --> false
5792 if (RHS.isNegative())
5793 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
5795 case ICmpInst::ICMP_SLE:
5796 // (float)int <= 4.4 --> int <= 4
5797 // (float)int <= -4.4 --> int < -4
5798 if (RHS.isNegative())
5799 Pred = ICmpInst::ICMP_SLT;
5801 case ICmpInst::ICMP_ULT:
5802 // (float)int < -4.4 --> false
5803 // (float)int < 4.4 --> int <= 4
5804 if (RHS.isNegative())
5805 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
5806 Pred = ICmpInst::ICMP_ULE;
5808 case ICmpInst::ICMP_SLT:
5809 // (float)int < -4.4 --> int < -4
5810 // (float)int < 4.4 --> int <= 4
5811 if (!RHS.isNegative())
5812 Pred = ICmpInst::ICMP_SLE;
5814 case ICmpInst::ICMP_UGT:
5815 // (float)int > 4.4 --> int > 4
5816 // (float)int > -4.4 --> true
5817 if (RHS.isNegative())
5818 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
5820 case ICmpInst::ICMP_SGT:
5821 // (float)int > 4.4 --> int > 4
5822 // (float)int > -4.4 --> int >= -4
5823 if (RHS.isNegative())
5824 Pred = ICmpInst::ICMP_SGE;
5826 case ICmpInst::ICMP_UGE:
5827 // (float)int >= -4.4 --> true
5828 // (float)int >= 4.4 --> int > 4
5829 if (!RHS.isNegative())
5830 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
5831 Pred = ICmpInst::ICMP_UGT;
5833 case ICmpInst::ICMP_SGE:
5834 // (float)int >= -4.4 --> int >= -4
5835 // (float)int >= 4.4 --> int > 4
5836 if (!RHS.isNegative())
5837 Pred = ICmpInst::ICMP_SGT;
5843 // Lower this FP comparison into an appropriate integer version of the
5845 return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt);
5848 Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
5849 bool Changed = SimplifyCompare(I);
5850 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
5852 // Fold trivial predicates.
5853 if (I.getPredicate() == FCmpInst::FCMP_FALSE)
5854 return ReplaceInstUsesWith(I, ConstantInt::get(I.getType(), 0));
5855 if (I.getPredicate() == FCmpInst::FCMP_TRUE)
5856 return ReplaceInstUsesWith(I, ConstantInt::get(I.getType(), 1));
5858 // Simplify 'fcmp pred X, X'
5860 switch (I.getPredicate()) {
5861 default: llvm_unreachable("Unknown predicate!");
5862 case FCmpInst::FCMP_UEQ: // True if unordered or equal
5863 case FCmpInst::FCMP_UGE: // True if unordered, greater than, or equal
5864 case FCmpInst::FCMP_ULE: // True if unordered, less than, or equal
5865 return ReplaceInstUsesWith(I, ConstantInt::get(I.getType(), 1));
5866 case FCmpInst::FCMP_OGT: // True if ordered and greater than
5867 case FCmpInst::FCMP_OLT: // True if ordered and less than
5868 case FCmpInst::FCMP_ONE: // True if ordered and operands are unequal
5869 return ReplaceInstUsesWith(I, ConstantInt::get(I.getType(), 0));
5871 case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
5872 case FCmpInst::FCMP_ULT: // True if unordered or less than
5873 case FCmpInst::FCMP_UGT: // True if unordered or greater than
5874 case FCmpInst::FCMP_UNE: // True if unordered or not equal
5875 // Canonicalize these to be 'fcmp uno %X, 0.0'.
5876 I.setPredicate(FCmpInst::FCMP_UNO);
5877 I.setOperand(1, Constant::getNullValue(Op0->getType()));
5880 case FCmpInst::FCMP_ORD: // True if ordered (no nans)
5881 case FCmpInst::FCMP_OEQ: // True if ordered and equal
5882 case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
5883 case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
5884 // Canonicalize these to be 'fcmp ord %X, 0.0'.
5885 I.setPredicate(FCmpInst::FCMP_ORD);
5886 I.setOperand(1, Constant::getNullValue(Op0->getType()));
5891 if (isa<UndefValue>(Op1)) // fcmp pred X, undef -> undef
5892 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
5894 // Handle fcmp with constant RHS
5895 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
5896 // If the constant is a nan, see if we can fold the comparison based on it.
5897 if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
5898 if (CFP->getValueAPF().isNaN()) {
5899 if (FCmpInst::isOrdered(I.getPredicate())) // True if ordered and...
5900 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
5901 assert(FCmpInst::isUnordered(I.getPredicate()) &&
5902 "Comparison must be either ordered or unordered!");
5903 // True if unordered.
5904 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
5908 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
5909 switch (LHSI->getOpcode()) {
5910 case Instruction::PHI:
5911 // Only fold fcmp into the PHI if the phi and fcmp are in the same
5912 // block. If in the same block, we're encouraging jump threading. If
5913 // not, we are just pessimizing the code by making an i1 phi.
5914 if (LHSI->getParent() == I.getParent())
5915 if (Instruction *NV = FoldOpIntoPhi(I, true))
5918 case Instruction::SIToFP:
5919 case Instruction::UIToFP:
5920 if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC))
5923 case Instruction::Select:
5924 // If either operand of the select is a constant, we can fold the
5925 // comparison into the select arms, which will cause one to be
5926 // constant folded and the select turned into a bitwise or.
5927 Value *Op1 = 0, *Op2 = 0;
5928 if (LHSI->hasOneUse()) {
5929 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
5930 // Fold the known value into the constant operand.
5931 Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
5932 // Insert a new FCmp of the other select operand.
5933 Op2 = Builder->CreateFCmp(I.getPredicate(),
5934 LHSI->getOperand(2), RHSC, I.getName());
5935 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
5936 // Fold the known value into the constant operand.
5937 Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
5938 // Insert a new FCmp of the other select operand.
5939 Op1 = Builder->CreateFCmp(I.getPredicate(), LHSI->getOperand(1),
5945 return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
5950 return Changed ? &I : 0;
5953 Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
5954 bool Changed = SimplifyCompare(I);
5955 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
5956 const Type *Ty = Op0->getType();
5960 return ReplaceInstUsesWith(I, ConstantInt::get(I.getType(),
5961 I.isTrueWhenEqual()));
5963 if (isa<UndefValue>(Op1)) // X icmp undef -> undef
5964 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
5966 // icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
5967 // addresses never equal each other! We already know that Op0 != Op1.
5968 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
5969 isa<ConstantPointerNull>(Op0)) &&
5970 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
5971 isa<ConstantPointerNull>(Op1)))
5972 return ReplaceInstUsesWith(I, ConstantInt::get(Type::getInt1Ty(*Context),
5973 !I.isTrueWhenEqual()));
5975 // icmp's with boolean values can always be turned into bitwise operations
5976 if (Ty == Type::getInt1Ty(*Context)) {
5977 switch (I.getPredicate()) {
5978 default: llvm_unreachable("Invalid icmp instruction!");
5979 case ICmpInst::ICMP_EQ: { // icmp eq i1 A, B -> ~(A^B)
5980 Value *Xor = Builder->CreateXor(Op0, Op1, I.getName()+"tmp");
5981 return BinaryOperator::CreateNot(Xor);
5983 case ICmpInst::ICMP_NE: // icmp eq i1 A, B -> A^B
5984 return BinaryOperator::CreateXor(Op0, Op1);
5986 case ICmpInst::ICMP_UGT:
5987 std::swap(Op0, Op1); // Change icmp ugt -> icmp ult
5989 case ICmpInst::ICMP_ULT:{ // icmp ult i1 A, B -> ~A & B
5990 Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
5991 return BinaryOperator::CreateAnd(Not, Op1);
5993 case ICmpInst::ICMP_SGT:
5994 std::swap(Op0, Op1); // Change icmp sgt -> icmp slt
5996 case ICmpInst::ICMP_SLT: { // icmp slt i1 A, B -> A & ~B
5997 Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
5998 return BinaryOperator::CreateAnd(Not, Op0);
6000 case ICmpInst::ICMP_UGE:
6001 std::swap(Op0, Op1); // Change icmp uge -> icmp ule
6003 case ICmpInst::ICMP_ULE: { // icmp ule i1 A, B -> ~A | B
6004 Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
6005 return BinaryOperator::CreateOr(Not, Op1);
6007 case ICmpInst::ICMP_SGE:
6008 std::swap(Op0, Op1); // Change icmp sge -> icmp sle
6010 case ICmpInst::ICMP_SLE: { // icmp sle i1 A, B -> A | ~B
6011 Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
6012 return BinaryOperator::CreateOr(Not, Op0);
6017 unsigned BitWidth = 0;
6019 BitWidth = TD->getTypeSizeInBits(Ty->getScalarType());
6020 else if (Ty->isIntOrIntVector())
6021 BitWidth = Ty->getScalarSizeInBits();
6023 bool isSignBit = false;
6025 // See if we are doing a comparison with a constant.
6026 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
6027 Value *A = 0, *B = 0;
6029 // (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B)
6030 if (I.isEquality() && CI->isNullValue() &&
6031 match(Op0, m_Sub(m_Value(A), m_Value(B)))) {
6032 // (icmp cond A B) if cond is equality
6033 return new ICmpInst(I.getPredicate(), A, B);
6036 // If we have an icmp le or icmp ge instruction, turn it into the
6037 // appropriate icmp lt or icmp gt instruction. This allows us to rely on
6038 // them being folded in the code below.
6039 switch (I.getPredicate()) {
6041 case ICmpInst::ICMP_ULE:
6042 if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
6043 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
6044 return new ICmpInst(ICmpInst::ICMP_ULT, Op0,
6046 case ICmpInst::ICMP_SLE:
6047 if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
6048 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
6049 return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
6051 case ICmpInst::ICMP_UGE:
6052 if (CI->isMinValue(false)) // A >=u MIN -> TRUE
6053 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
6054 return new ICmpInst(ICmpInst::ICMP_UGT, Op0,
6056 case ICmpInst::ICMP_SGE:
6057 if (CI->isMinValue(true)) // A >=s MIN -> TRUE
6058 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
6059 return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
6063 // If this comparison is a normal comparison, it demands all
6064 // bits, if it is a sign bit comparison, it only demands the sign bit.
6066 isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
6069 // See if we can fold the comparison based on range information we can get
6070 // by checking whether bits are known to be zero or one in the input.
6071 if (BitWidth != 0) {
6072 APInt Op0KnownZero(BitWidth, 0), Op0KnownOne(BitWidth, 0);
6073 APInt Op1KnownZero(BitWidth, 0), Op1KnownOne(BitWidth, 0);
6075 if (SimplifyDemandedBits(I.getOperandUse(0),
6076 isSignBit ? APInt::getSignBit(BitWidth)
6077 : APInt::getAllOnesValue(BitWidth),
6078 Op0KnownZero, Op0KnownOne, 0))
6080 if (SimplifyDemandedBits(I.getOperandUse(1),
6081 APInt::getAllOnesValue(BitWidth),
6082 Op1KnownZero, Op1KnownOne, 0))
6085 // Given the known and unknown bits, compute a range that the LHS could be
6086 // in. Compute the Min, Max and RHS values based on the known bits. For the
6087 // EQ and NE we use unsigned values.
6088 APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0);
6089 APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0);
6090 if (ICmpInst::isSignedPredicate(I.getPredicate())) {
6091 ComputeSignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
6093 ComputeSignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
6096 ComputeUnsignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
6098 ComputeUnsignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
6102 // If Min and Max are known to be the same, then SimplifyDemandedBits
6103 // figured out that the LHS is a constant. Just constant fold this now so
6104 // that code below can assume that Min != Max.
6105 if (!isa<Constant>(Op0) && Op0Min == Op0Max)
6106 return new ICmpInst(I.getPredicate(),
6107 ConstantInt::get(*Context, Op0Min), Op1);
6108 if (!isa<Constant>(Op1) && Op1Min == Op1Max)
6109 return new ICmpInst(I.getPredicate(), Op0,
6110 ConstantInt::get(*Context, Op1Min));
6112 // Based on the range information we know about the LHS, see if we can
6113 // simplify this comparison. For example, (x&4) < 8 is always true.
6114 switch (I.getPredicate()) {
6115 default: llvm_unreachable("Unknown icmp opcode!");
6116 case ICmpInst::ICMP_EQ:
6117 if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
6118 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
6120 case ICmpInst::ICMP_NE:
6121 if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
6122 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
6124 case ICmpInst::ICMP_ULT:
6125 if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B)
6126 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
6127 if (Op0Min.uge(Op1Max)) // A <u B -> false if min(A) >= max(B)
6128 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
6129 if (Op1Min == Op0Max) // A <u B -> A != B if max(A) == min(B)
6130 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
6131 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
6132 if (Op1Max == Op0Min+1) // A <u C -> A == C-1 if min(A)+1 == C
6133 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
6136 // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear
6137 if (CI->isMinValue(true))
6138 return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
6139 Constant::getAllOnesValue(Op0->getType()));
6142 case ICmpInst::ICMP_UGT:
6143 if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B)
6144 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
6145 if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B)
6146 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
6148 if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B)
6149 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
6150 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
6151 if (Op1Min == Op0Max-1) // A >u C -> A == C+1 if max(a)-1 == C
6152 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
6155 // (x >u 2147483647) -> (x <s 0) -> true if sign bit set
6156 if (CI->isMaxValue(true))
6157 return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
6158 Constant::getNullValue(Op0->getType()));
6161 case ICmpInst::ICMP_SLT:
6162 if (Op0Max.slt(Op1Min)) // A <s B -> true if max(A) < min(C)
6163 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
6164 if (Op0Min.sge(Op1Max)) // A <s B -> false if min(A) >= max(C)
6165 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
6166 if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B)
6167 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
6168 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
6169 if (Op1Max == Op0Min+1) // A <s C -> A == C-1 if min(A)+1 == C
6170 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
6174 case ICmpInst::ICMP_SGT:
6175 if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B)
6176 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
6177 if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B)
6178 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
6180 if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B)
6181 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
6182 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
6183 if (Op1Min == Op0Max-1) // A >s C -> A == C+1 if max(A)-1 == C
6184 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
6188 case ICmpInst::ICMP_SGE:
6189 assert(!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!");
6190 if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B)
6191 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
6192 if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B)
6193 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
6195 case ICmpInst::ICMP_SLE:
6196 assert(!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!");
6197 if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B)
6198 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
6199 if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B)
6200 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
6202 case ICmpInst::ICMP_UGE:
6203 assert(!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!");
6204 if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B)
6205 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
6206 if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B)
6207 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
6209 case ICmpInst::ICMP_ULE:
6210 assert(!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!");
6211 if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B)
6212 return ReplaceInstUsesWith(I, ConstantInt::getTrue(*Context));
6213 if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B)
6214 return ReplaceInstUsesWith(I, ConstantInt::getFalse(*Context));
6218 // Turn a signed comparison into an unsigned one if both operands
6219 // are known to have the same sign.
6220 if (I.isSignedPredicate() &&
6221 ((Op0KnownZero.isNegative() && Op1KnownZero.isNegative()) ||
6222 (Op0KnownOne.isNegative() && Op1KnownOne.isNegative())))
6223 return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1);
6226 // Test if the ICmpInst instruction is used exclusively by a select as
6227 // part of a minimum or maximum operation. If so, refrain from doing
6228 // any other folding. This helps out other analyses which understand
6229 // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
6230 // and CodeGen. And in this case, at least one of the comparison
6231 // operands has at least one user besides the compare (the select),
6232 // which would often largely negate the benefit of folding anyway.
6234 if (SelectInst *SI = dyn_cast<SelectInst>(*I.use_begin()))
6235 if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
6236 (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
6239 // See if we are doing a comparison between a constant and an instruction that
6240 // can be folded into the comparison.
6241 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
6242 // Since the RHS is a ConstantInt (CI), if the left hand side is an
6243 // instruction, see if that instruction also has constants so that the
6244 // instruction can be folded into the icmp
6245 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
6246 if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI))
6250 // Handle icmp with constant (but not simple integer constant) RHS
6251 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
6252 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
6253 switch (LHSI->getOpcode()) {
6254 case Instruction::GetElementPtr:
6255 if (RHSC->isNullValue()) {
6256 // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
6257 bool isAllZeros = true;
6258 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
6259 if (!isa<Constant>(LHSI->getOperand(i)) ||
6260 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
6265 return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
6266 Constant::getNullValue(LHSI->getOperand(0)->getType()));
6270 case Instruction::PHI:
6271 // Only fold icmp into the PHI if the phi and icmp are in the same
6272 // block. If in the same block, we're encouraging jump threading. If
6273 // not, we are just pessimizing the code by making an i1 phi.
6274 if (LHSI->getParent() == I.getParent())
6275 if (Instruction *NV = FoldOpIntoPhi(I, true))
6278 case Instruction::Select: {
6279 // If either operand of the select is a constant, we can fold the
6280 // comparison into the select arms, which will cause one to be
6281 // constant folded and the select turned into a bitwise or.
6282 Value *Op1 = 0, *Op2 = 0;
6283 if (LHSI->hasOneUse()) {
6284 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
6285 // Fold the known value into the constant operand.
6286 Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
6287 // Insert a new ICmp of the other select operand.
6288 Op2 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(2),
6290 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
6291 // Fold the known value into the constant operand.
6292 Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
6293 // Insert a new ICmp of the other select operand.
6294 Op1 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(1),
6300 return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
6303 case Instruction::Call:
6304 // If we have (malloc != null), and if the malloc has a single use, we
6305 // can assume it is successful and remove the malloc.
6306 if (isMalloc(LHSI) && LHSI->hasOneUse() &&
6307 isa<ConstantPointerNull>(RHSC)) {
6308 // Need to explicitly erase malloc call here, instead of adding it to
6309 // Worklist, because it won't get DCE'd from the Worklist since
6310 // isInstructionTriviallyDead() returns false for function calls.
6311 // It is OK to replace LHSI/MallocCall with Undef because the
6312 // instruction that uses it will be erased via Worklist.
6313 if (extractMallocCall(LHSI)) {
6314 LHSI->replaceAllUsesWith(UndefValue::get(LHSI->getType()));
6315 EraseInstFromFunction(*LHSI);
6316 return ReplaceInstUsesWith(I,
6317 ConstantInt::get(Type::getInt1Ty(*Context),
6318 !I.isTrueWhenEqual()));
6320 if (CallInst* MallocCall = extractMallocCallFromBitCast(LHSI))
6321 if (MallocCall->hasOneUse()) {
6322 MallocCall->replaceAllUsesWith(
6323 UndefValue::get(MallocCall->getType()));
6324 EraseInstFromFunction(*MallocCall);
6325 Worklist.Add(LHSI); // The malloc's bitcast use.
6326 return ReplaceInstUsesWith(I,
6327 ConstantInt::get(Type::getInt1Ty(*Context),
6328 !I.isTrueWhenEqual()));
6335 // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
6336 if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0))
6337 if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
6339 if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1))
6340 if (Instruction *NI = FoldGEPICmp(GEP, Op0,
6341 ICmpInst::getSwappedPredicate(I.getPredicate()), I))
6344 // Test to see if the operands of the icmp are casted versions of other
6345 // values. If the ptr->ptr cast can be stripped off both arguments, we do so
6347 if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
6348 if (isa<PointerType>(Op0->getType()) &&
6349 (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
6350 // We keep moving the cast from the left operand over to the right
6351 // operand, where it can often be eliminated completely.
6352 Op0 = CI->getOperand(0);
6354 // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
6355 // so eliminate it as well.
6356 if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
6357 Op1 = CI2->getOperand(0);
6359 // If Op1 is a constant, we can fold the cast into the constant.
6360 if (Op0->getType() != Op1->getType()) {
6361 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
6362 Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
6364 // Otherwise, cast the RHS right before the icmp
6365 Op1 = Builder->CreateBitCast(Op1, Op0->getType());
6368 return new ICmpInst(I.getPredicate(), Op0, Op1);
6372 if (isa<CastInst>(Op0)) {
6373 // Handle the special case of: icmp (cast bool to X), <cst>
6374 // This comes up when you have code like
6377 // For generality, we handle any zero-extension of any operand comparison
6378 // with a constant or another cast from the same type.
6379 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
6380 if (Instruction *R = visitICmpInstWithCastAndCast(I))
6384 // See if it's the same type of instruction on the left and right.
6385 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
6386 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
6387 if (Op0I->getOpcode() == Op1I->getOpcode() && Op0I->hasOneUse() &&
6388 Op1I->hasOneUse() && Op0I->getOperand(1) == Op1I->getOperand(1)) {
6389 switch (Op0I->getOpcode()) {
6391 case Instruction::Add:
6392 case Instruction::Sub:
6393 case Instruction::Xor:
6394 if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b
6395 return new ICmpInst(I.getPredicate(), Op0I->getOperand(0),
6396 Op1I->getOperand(0));
6397 // icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b
6398 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
6399 if (CI->getValue().isSignBit()) {
6400 ICmpInst::Predicate Pred = I.isSignedPredicate()
6401 ? I.getUnsignedPredicate()
6402 : I.getSignedPredicate();
6403 return new ICmpInst(Pred, Op0I->getOperand(0),
6404 Op1I->getOperand(0));
6407 if (CI->getValue().isMaxSignedValue()) {
6408 ICmpInst::Predicate Pred = I.isSignedPredicate()
6409 ? I.getUnsignedPredicate()
6410 : I.getSignedPredicate();
6411 Pred = I.getSwappedPredicate(Pred);
6412 return new ICmpInst(Pred, Op0I->getOperand(0),
6413 Op1I->getOperand(0));
6417 case Instruction::Mul:
6418 if (!I.isEquality())
6421 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
6422 // a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask
6423 // Mask = -1 >> count-trailing-zeros(Cst).
6424 if (!CI->isZero() && !CI->isOne()) {
6425 const APInt &AP = CI->getValue();
6426 ConstantInt *Mask = ConstantInt::get(*Context,
6427 APInt::getLowBitsSet(AP.getBitWidth(),
6429 AP.countTrailingZeros()));
6430 Value *And1 = Builder->CreateAnd(Op0I->getOperand(0), Mask);
6431 Value *And2 = Builder->CreateAnd(Op1I->getOperand(0), Mask);
6432 return new ICmpInst(I.getPredicate(), And1, And2);
6441 // ~x < ~y --> y < x
6443 if (match(Op0, m_Not(m_Value(A))) &&
6444 match(Op1, m_Not(m_Value(B))))
6445 return new ICmpInst(I.getPredicate(), B, A);
6448 if (I.isEquality()) {
6449 Value *A, *B, *C, *D;
6451 // -x == -y --> x == y
6452 if (match(Op0, m_Neg(m_Value(A))) &&
6453 match(Op1, m_Neg(m_Value(B))))
6454 return new ICmpInst(I.getPredicate(), A, B);
6456 if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
6457 if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
6458 Value *OtherVal = A == Op1 ? B : A;
6459 return new ICmpInst(I.getPredicate(), OtherVal,
6460 Constant::getNullValue(A->getType()));
6463 if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
6464 // A^c1 == C^c2 --> A == C^(c1^c2)
6465 ConstantInt *C1, *C2;
6466 if (match(B, m_ConstantInt(C1)) &&
6467 match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) {
6469 ConstantInt::get(*Context, C1->getValue() ^ C2->getValue());
6470 Value *Xor = Builder->CreateXor(C, NC, "tmp");
6471 return new ICmpInst(I.getPredicate(), A, Xor);
6474 // A^B == A^D -> B == D
6475 if (A == C) return new ICmpInst(I.getPredicate(), B, D);
6476 if (A == D) return new ICmpInst(I.getPredicate(), B, C);
6477 if (B == C) return new ICmpInst(I.getPredicate(), A, D);
6478 if (B == D) return new ICmpInst(I.getPredicate(), A, C);
6482 if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
6483 (A == Op0 || B == Op0)) {
6484 // A == (A^B) -> B == 0
6485 Value *OtherVal = A == Op0 ? B : A;
6486 return new ICmpInst(I.getPredicate(), OtherVal,
6487 Constant::getNullValue(A->getType()));
6490 // (A-B) == A -> B == 0
6491 if (match(Op0, m_Sub(m_Specific(Op1), m_Value(B))))
6492 return new ICmpInst(I.getPredicate(), B,
6493 Constant::getNullValue(B->getType()));
6495 // A == (A-B) -> B == 0
6496 if (match(Op1, m_Sub(m_Specific(Op0), m_Value(B))))
6497 return new ICmpInst(I.getPredicate(), B,
6498 Constant::getNullValue(B->getType()));
6500 // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
6501 if (Op0->hasOneUse() && Op1->hasOneUse() &&
6502 match(Op0, m_And(m_Value(A), m_Value(B))) &&
6503 match(Op1, m_And(m_Value(C), m_Value(D)))) {
6504 Value *X = 0, *Y = 0, *Z = 0;
6507 X = B; Y = D; Z = A;
6508 } else if (A == D) {
6509 X = B; Y = C; Z = A;
6510 } else if (B == C) {
6511 X = A; Y = D; Z = B;
6512 } else if (B == D) {
6513 X = A; Y = C; Z = B;
6516 if (X) { // Build (X^Y) & Z
6517 Op1 = Builder->CreateXor(X, Y, "tmp");
6518 Op1 = Builder->CreateAnd(Op1, Z, "tmp");
6519 I.setOperand(0, Op1);
6520 I.setOperand(1, Constant::getNullValue(Op1->getType()));
6525 return Changed ? &I : 0;
6529 /// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS
6530 /// and CmpRHS are both known to be integer constants.
6531 Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
6532 ConstantInt *DivRHS) {
6533 ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1));
6534 const APInt &CmpRHSV = CmpRHS->getValue();
6536 // FIXME: If the operand types don't match the type of the divide
6537 // then don't attempt this transform. The code below doesn't have the
6538 // logic to deal with a signed divide and an unsigned compare (and
6539 // vice versa). This is because (x /s C1) <s C2 produces different
6540 // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even
6541 // (x /u C1) <u C2. Simply casting the operands and result won't
6542 // work. :( The if statement below tests that condition and bails
6544 bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv;
6545 if (!ICI.isEquality() && DivIsSigned != ICI.isSignedPredicate())
6547 if (DivRHS->isZero())
6548 return 0; // The ProdOV computation fails on divide by zero.
6549 if (DivIsSigned && DivRHS->isAllOnesValue())
6550 return 0; // The overflow computation also screws up here
6551 if (DivRHS->isOne())
6552 return 0; // Not worth bothering, and eliminates some funny cases
6555 // Compute Prod = CI * DivRHS. We are essentially solving an equation
6556 // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and
6557 // C2 (CI). By solving for X we can turn this into a range check
6558 // instead of computing a divide.
6559 Constant *Prod = ConstantExpr::getMul(CmpRHS, DivRHS);
6561 // Determine if the product overflows by seeing if the product is
6562 // not equal to the divide. Make sure we do the same kind of divide
6563 // as in the LHS instruction that we're folding.
6564 bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) :
6565 ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS;
6567 // Get the ICmp opcode
6568 ICmpInst::Predicate Pred = ICI.getPredicate();
6570 // Figure out the interval that is being checked. For example, a comparison
6571 // like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
6572 // Compute this interval based on the constants involved and the signedness of
6573 // the compare/divide. This computes a half-open interval, keeping track of
6574 // whether either value in the interval overflows. After analysis each
6575 // overflow variable is set to 0 if it's corresponding bound variable is valid
6576 // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
6577 int LoOverflow = 0, HiOverflow = 0;
6578 Constant *LoBound = 0, *HiBound = 0;
6580 if (!DivIsSigned) { // udiv
6581 // e.g. X/5 op 3 --> [15, 20)
6583 HiOverflow = LoOverflow = ProdOV;
6585 HiOverflow = AddWithOverflow(HiBound, LoBound, DivRHS, Context, false);
6586 } else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0.
6587 if (CmpRHSV == 0) { // (X / pos) op 0
6588 // Can't overflow. e.g. X/2 op 0 --> [-1, 2)
6589 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
6591 } else if (CmpRHSV.isStrictlyPositive()) { // (X / pos) op pos
6592 LoBound = Prod; // e.g. X/5 op 3 --> [15, 20)
6593 HiOverflow = LoOverflow = ProdOV;
6595 HiOverflow = AddWithOverflow(HiBound, Prod, DivRHS, Context, true);
6596 } else { // (X / pos) op neg
6597 // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
6598 HiBound = AddOne(Prod);
6599 LoOverflow = HiOverflow = ProdOV ? -1 : 0;
6601 ConstantInt* DivNeg =
6602 cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
6603 LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg, Context,
6607 } else if (DivRHS->getValue().isNegative()) { // Divisor is < 0.
6608 if (CmpRHSV == 0) { // (X / neg) op 0
6609 // e.g. X/-5 op 0 --> [-4, 5)
6610 LoBound = AddOne(DivRHS);
6611 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
6612 if (HiBound == DivRHS) { // -INTMIN = INTMIN
6613 HiOverflow = 1; // [INTMIN+1, overflow)
6614 HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN
6616 } else if (CmpRHSV.isStrictlyPositive()) { // (X / neg) op pos
6617 // e.g. X/-5 op 3 --> [-19, -14)
6618 HiBound = AddOne(Prod);
6619 HiOverflow = LoOverflow = ProdOV ? -1 : 0;
6621 LoOverflow = AddWithOverflow(LoBound, HiBound,
6622 DivRHS, Context, true) ? -1 : 0;
6623 } else { // (X / neg) op neg
6624 LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20)
6625 LoOverflow = HiOverflow = ProdOV;
6627 HiOverflow = SubWithOverflow(HiBound, Prod, DivRHS, Context, true);
6630 // Dividing by a negative swaps the condition. LT <-> GT
6631 Pred = ICmpInst::getSwappedPredicate(Pred);
6634 Value *X = DivI->getOperand(0);
6636 default: llvm_unreachable("Unhandled icmp opcode!");
6637 case ICmpInst::ICMP_EQ:
6638 if (LoOverflow && HiOverflow)
6639 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
6640 else if (HiOverflow)
6641 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
6642 ICmpInst::ICMP_UGE, X, LoBound);
6643 else if (LoOverflow)
6644 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
6645 ICmpInst::ICMP_ULT, X, HiBound);
6647 return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, true, ICI);
6648 case ICmpInst::ICMP_NE:
6649 if (LoOverflow && HiOverflow)
6650 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
6651 else if (HiOverflow)
6652 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
6653 ICmpInst::ICMP_ULT, X, LoBound);
6654 else if (LoOverflow)
6655 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
6656 ICmpInst::ICMP_UGE, X, HiBound);
6658 return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, false, ICI);
6659 case ICmpInst::ICMP_ULT:
6660 case ICmpInst::ICMP_SLT:
6661 if (LoOverflow == +1) // Low bound is greater than input range.
6662 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
6663 if (LoOverflow == -1) // Low bound is less than input range.
6664 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
6665 return new ICmpInst(Pred, X, LoBound);
6666 case ICmpInst::ICMP_UGT:
6667 case ICmpInst::ICMP_SGT:
6668 if (HiOverflow == +1) // High bound greater than input range.
6669 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
6670 else if (HiOverflow == -1) // High bound less than input range.
6671 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
6672 if (Pred == ICmpInst::ICMP_UGT)
6673 return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
6675 return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
6680 /// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
6682 Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
6685 const APInt &RHSV = RHS->getValue();
6687 switch (LHSI->getOpcode()) {
6688 case Instruction::Trunc:
6689 if (ICI.isEquality() && LHSI->hasOneUse()) {
6690 // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all
6691 // of the high bits truncated out of x are known.
6692 unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(),
6693 SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits();
6694 APInt Mask(APInt::getHighBitsSet(SrcBits, SrcBits-DstBits));
6695 APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0);
6696 ComputeMaskedBits(LHSI->getOperand(0), Mask, KnownZero, KnownOne);
6698 // If all the high bits are known, we can do this xform.
6699 if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) {
6700 // Pull in the high bits from known-ones set.
6701 APInt NewRHS(RHS->getValue());
6702 NewRHS.zext(SrcBits);
6704 return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
6705 ConstantInt::get(*Context, NewRHS));
6710 case Instruction::Xor: // (icmp pred (xor X, XorCST), CI)
6711 if (ConstantInt *XorCST = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
6712 // If this is a comparison that tests the signbit (X < 0) or (x > -1),
6714 if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) ||
6715 (ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) {
6716 Value *CompareVal = LHSI->getOperand(0);
6718 // If the sign bit of the XorCST is not set, there is no change to
6719 // the operation, just stop using the Xor.
6720 if (!XorCST->getValue().isNegative()) {
6721 ICI.setOperand(0, CompareVal);
6726 // Was the old condition true if the operand is positive?
6727 bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT;
6729 // If so, the new one isn't.
6730 isTrueIfPositive ^= true;
6732 if (isTrueIfPositive)
6733 return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal,
6736 return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal,
6740 if (LHSI->hasOneUse()) {
6741 // (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit))
6742 if (!ICI.isEquality() && XorCST->getValue().isSignBit()) {
6743 const APInt &SignBit = XorCST->getValue();
6744 ICmpInst::Predicate Pred = ICI.isSignedPredicate()
6745 ? ICI.getUnsignedPredicate()
6746 : ICI.getSignedPredicate();
6747 return new ICmpInst(Pred, LHSI->getOperand(0),
6748 ConstantInt::get(*Context, RHSV ^ SignBit));
6751 // (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A)
6752 if (!ICI.isEquality() && XorCST->getValue().isMaxSignedValue()) {
6753 const APInt &NotSignBit = XorCST->getValue();
6754 ICmpInst::Predicate Pred = ICI.isSignedPredicate()
6755 ? ICI.getUnsignedPredicate()
6756 : ICI.getSignedPredicate();
6757 Pred = ICI.getSwappedPredicate(Pred);
6758 return new ICmpInst(Pred, LHSI->getOperand(0),
6759 ConstantInt::get(*Context, RHSV ^ NotSignBit));
6764 case Instruction::And: // (icmp pred (and X, AndCST), RHS)
6765 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
6766 LHSI->getOperand(0)->hasOneUse()) {
6767 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
6769 // If the LHS is an AND of a truncating cast, we can widen the
6770 // and/compare to be the input width without changing the value
6771 // produced, eliminating a cast.
6772 if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) {
6773 // We can do this transformation if either the AND constant does not
6774 // have its sign bit set or if it is an equality comparison.
6775 // Extending a relational comparison when we're checking the sign
6776 // bit would not work.
6777 if (Cast->hasOneUse() &&
6778 (ICI.isEquality() ||
6779 (AndCST->getValue().isNonNegative() && RHSV.isNonNegative()))) {
6781 cast<IntegerType>(Cast->getOperand(0)->getType())->getBitWidth();
6782 APInt NewCST = AndCST->getValue();
6783 NewCST.zext(BitWidth);
6785 NewCI.zext(BitWidth);
6787 Builder->CreateAnd(Cast->getOperand(0),
6788 ConstantInt::get(*Context, NewCST), LHSI->getName());
6789 return new ICmpInst(ICI.getPredicate(), NewAnd,
6790 ConstantInt::get(*Context, NewCI));
6794 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
6795 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
6796 // happens a LOT in code produced by the C front-end, for bitfield
6798 BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
6799 if (Shift && !Shift->isShift())
6803 ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0;
6804 const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift.
6805 const Type *AndTy = AndCST->getType(); // Type of the and.
6807 // We can fold this as long as we can't shift unknown bits
6808 // into the mask. This can only happen with signed shift
6809 // rights, as they sign-extend.
6811 bool CanFold = Shift->isLogicalShift();
6813 // To test for the bad case of the signed shr, see if any
6814 // of the bits shifted in could be tested after the mask.
6815 uint32_t TyBits = Ty->getPrimitiveSizeInBits();
6816 int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits);
6818 uint32_t BitWidth = AndTy->getPrimitiveSizeInBits();
6819 if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) &
6820 AndCST->getValue()) == 0)
6826 if (Shift->getOpcode() == Instruction::Shl)
6827 NewCst = ConstantExpr::getLShr(RHS, ShAmt);
6829 NewCst = ConstantExpr::getShl(RHS, ShAmt);
6831 // Check to see if we are shifting out any of the bits being
6833 if (ConstantExpr::get(Shift->getOpcode(),
6834 NewCst, ShAmt) != RHS) {
6835 // If we shifted bits out, the fold is not going to work out.
6836 // As a special case, check to see if this means that the
6837 // result is always true or false now.
6838 if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
6839 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
6840 if (ICI.getPredicate() == ICmpInst::ICMP_NE)
6841 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
6843 ICI.setOperand(1, NewCst);
6844 Constant *NewAndCST;
6845 if (Shift->getOpcode() == Instruction::Shl)
6846 NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt);
6848 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
6849 LHSI->setOperand(1, NewAndCST);
6850 LHSI->setOperand(0, Shift->getOperand(0));
6851 Worklist.Add(Shift); // Shift is dead.
6857 // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is
6858 // preferable because it allows the C<<Y expression to be hoisted out
6859 // of a loop if Y is invariant and X is not.
6860 if (Shift && Shift->hasOneUse() && RHSV == 0 &&
6861 ICI.isEquality() && !Shift->isArithmeticShift() &&
6862 !isa<Constant>(Shift->getOperand(0))) {
6865 if (Shift->getOpcode() == Instruction::LShr) {
6866 NS = Builder->CreateShl(AndCST, Shift->getOperand(1), "tmp");
6868 // Insert a logical shift.
6869 NS = Builder->CreateLShr(AndCST, Shift->getOperand(1), "tmp");
6872 // Compute X & (C << Y).
6874 Builder->CreateAnd(Shift->getOperand(0), NS, LHSI->getName());
6876 ICI.setOperand(0, NewAnd);
6882 case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI)
6883 ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
6886 uint32_t TypeBits = RHSV.getBitWidth();
6888 // Check that the shift amount is in range. If not, don't perform
6889 // undefined shifts. When the shift is visited it will be
6891 if (ShAmt->uge(TypeBits))
6894 if (ICI.isEquality()) {
6895 // If we are comparing against bits always shifted out, the
6896 // comparison cannot succeed.
6898 ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt),
6900 if (Comp != RHS) {// Comparing against a bit that we know is zero.
6901 bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
6902 Constant *Cst = ConstantInt::get(Type::getInt1Ty(*Context), IsICMP_NE);
6903 return ReplaceInstUsesWith(ICI, Cst);
6906 if (LHSI->hasOneUse()) {
6907 // Otherwise strength reduce the shift into an and.
6908 uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
6910 ConstantInt::get(*Context, APInt::getLowBitsSet(TypeBits,
6911 TypeBits-ShAmtVal));
6914 Builder->CreateAnd(LHSI->getOperand(0),Mask, LHSI->getName()+".mask");
6915 return new ICmpInst(ICI.getPredicate(), And,
6916 ConstantInt::get(*Context, RHSV.lshr(ShAmtVal)));
6920 // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
6921 bool TrueIfSigned = false;
6922 if (LHSI->hasOneUse() &&
6923 isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
6924 // (X << 31) <s 0 --> (X&1) != 0
6925 Constant *Mask = ConstantInt::get(*Context, APInt(TypeBits, 1) <<
6926 (TypeBits-ShAmt->getZExtValue()-1));
6928 Builder->CreateAnd(LHSI->getOperand(0), Mask, LHSI->getName()+".mask");
6929 return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
6930 And, Constant::getNullValue(And->getType()));
6935 case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI)
6936 case Instruction::AShr: {
6937 // Only handle equality comparisons of shift-by-constant.
6938 ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
6939 if (!ShAmt || !ICI.isEquality()) break;
6941 // Check that the shift amount is in range. If not, don't perform
6942 // undefined shifts. When the shift is visited it will be
6944 uint32_t TypeBits = RHSV.getBitWidth();
6945 if (ShAmt->uge(TypeBits))
6948 uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
6950 // If we are comparing against bits always shifted out, the
6951 // comparison cannot succeed.
6952 APInt Comp = RHSV << ShAmtVal;
6953 if (LHSI->getOpcode() == Instruction::LShr)
6954 Comp = Comp.lshr(ShAmtVal);
6956 Comp = Comp.ashr(ShAmtVal);
6958 if (Comp != RHSV) { // Comparing against a bit that we know is zero.
6959 bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
6960 Constant *Cst = ConstantInt::get(Type::getInt1Ty(*Context), IsICMP_NE);
6961 return ReplaceInstUsesWith(ICI, Cst);
6964 // Otherwise, check to see if the bits shifted out are known to be zero.
6965 // If so, we can compare against the unshifted value:
6966 // (X & 4) >> 1 == 2 --> (X & 4) == 4.
6967 if (LHSI->hasOneUse() &&
6968 MaskedValueIsZero(LHSI->getOperand(0),
6969 APInt::getLowBitsSet(Comp.getBitWidth(), ShAmtVal))) {
6970 return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
6971 ConstantExpr::getShl(RHS, ShAmt));
6974 if (LHSI->hasOneUse()) {
6975 // Otherwise strength reduce the shift into an and.
6976 APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
6977 Constant *Mask = ConstantInt::get(*Context, Val);
6979 Value *And = Builder->CreateAnd(LHSI->getOperand(0),
6980 Mask, LHSI->getName()+".mask");
6981 return new ICmpInst(ICI.getPredicate(), And,
6982 ConstantExpr::getShl(RHS, ShAmt));
6987 case Instruction::SDiv:
6988 case Instruction::UDiv:
6989 // Fold: icmp pred ([us]div X, C1), C2 -> range test
6990 // Fold this div into the comparison, producing a range check.
6991 // Determine, based on the divide type, what the range is being
6992 // checked. If there is an overflow on the low or high side, remember
6993 // it, otherwise compute the range [low, hi) bounding the new value.
6994 // See: InsertRangeTest above for the kinds of replacements possible.
6995 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1)))
6996 if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI),
7001 case Instruction::Add:
7002 // Fold: icmp pred (add, X, C1), C2
7004 if (!ICI.isEquality()) {
7005 ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(1));
7007 const APInt &LHSV = LHSC->getValue();
7009 ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV)
7012 if (ICI.isSignedPredicate()) {
7013 if (CR.getLower().isSignBit()) {
7014 return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0),
7015 ConstantInt::get(*Context, CR.getUpper()));
7016 } else if (CR.getUpper().isSignBit()) {
7017 return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0),
7018 ConstantInt::get(*Context, CR.getLower()));
7021 if (CR.getLower().isMinValue()) {
7022 return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0),
7023 ConstantInt::get(*Context, CR.getUpper()));
7024 } else if (CR.getUpper().isMinValue()) {
7025 return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0),
7026 ConstantInt::get(*Context, CR.getLower()));
7033 // Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
7034 if (ICI.isEquality()) {
7035 bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
7037 // If the first operand is (add|sub|and|or|xor|rem) with a constant, and
7038 // the second operand is a constant, simplify a bit.
7039 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) {
7040 switch (BO->getOpcode()) {
7041 case Instruction::SRem:
7042 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
7043 if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){
7044 const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
7045 if (V.sgt(APInt(V.getBitWidth(), 1)) && V.isPowerOf2()) {
7047 Builder->CreateURem(BO->getOperand(0), BO->getOperand(1),
7049 return new ICmpInst(ICI.getPredicate(), NewRem,
7050 Constant::getNullValue(BO->getType()));
7054 case Instruction::Add:
7055 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
7056 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
7057 if (BO->hasOneUse())
7058 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
7059 ConstantExpr::getSub(RHS, BOp1C));
7060 } else if (RHSV == 0) {
7061 // Replace ((add A, B) != 0) with (A != -B) if A or B is
7062 // efficiently invertible, or if the add has just this one use.
7063 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
7065 if (Value *NegVal = dyn_castNegVal(BOp1))
7066 return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
7067 else if (Value *NegVal = dyn_castNegVal(BOp0))
7068 return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
7069 else if (BO->hasOneUse()) {
7070 Value *Neg = Builder->CreateNeg(BOp1);
7072 return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
7076 case Instruction::Xor:
7077 // For the xor case, we can xor two constants together, eliminating
7078 // the explicit xor.
7079 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
7080 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
7081 ConstantExpr::getXor(RHS, BOC));
7084 case Instruction::Sub:
7085 // Replace (([sub|xor] A, B) != 0) with (A != B)
7087 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
7091 case Instruction::Or:
7092 // If bits are being or'd in that are not present in the constant we
7093 // are comparing against, then the comparison could never succeed!
7094 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
7095 Constant *NotCI = ConstantExpr::getNot(RHS);
7096 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
7097 return ReplaceInstUsesWith(ICI,
7098 ConstantInt::get(Type::getInt1Ty(*Context),
7103 case Instruction::And:
7104 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
7105 // If bits are being compared against that are and'd out, then the
7106 // comparison can never succeed!
7107 if ((RHSV & ~BOC->getValue()) != 0)
7108 return ReplaceInstUsesWith(ICI,
7109 ConstantInt::get(Type::getInt1Ty(*Context),
7112 // If we have ((X & C) == C), turn it into ((X & C) != 0).
7113 if (RHS == BOC && RHSV.isPowerOf2())
7114 return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
7115 ICmpInst::ICMP_NE, LHSI,
7116 Constant::getNullValue(RHS->getType()));
7118 // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
7119 if (BOC->getValue().isSignBit()) {
7120 Value *X = BO->getOperand(0);
7121 Constant *Zero = Constant::getNullValue(X->getType());
7122 ICmpInst::Predicate pred = isICMP_NE ?
7123 ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
7124 return new ICmpInst(pred, X, Zero);
7127 // ((X & ~7) == 0) --> X < 8
7128 if (RHSV == 0 && isHighOnes(BOC)) {
7129 Value *X = BO->getOperand(0);
7130 Constant *NegX = ConstantExpr::getNeg(BOC);
7131 ICmpInst::Predicate pred = isICMP_NE ?
7132 ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
7133 return new ICmpInst(pred, X, NegX);
7138 } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
7139 // Handle icmp {eq|ne} <intrinsic>, intcst.
7140 if (II->getIntrinsicID() == Intrinsic::bswap) {
7142 ICI.setOperand(0, II->getOperand(1));
7143 ICI.setOperand(1, ConstantInt::get(*Context, RHSV.byteSwap()));
7151 /// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
7152 /// We only handle extending casts so far.
7154 Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
7155 const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0));
7156 Value *LHSCIOp = LHSCI->getOperand(0);
7157 const Type *SrcTy = LHSCIOp->getType();
7158 const Type *DestTy = LHSCI->getType();
7161 // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
7162 // integer type is the same size as the pointer type.
7163 if (TD && LHSCI->getOpcode() == Instruction::PtrToInt &&
7164 TD->getPointerSizeInBits() ==
7165 cast<IntegerType>(DestTy)->getBitWidth()) {
7167 if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) {
7168 RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
7169 } else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) {
7170 RHSOp = RHSC->getOperand(0);
7171 // If the pointer types don't match, insert a bitcast.
7172 if (LHSCIOp->getType() != RHSOp->getType())
7173 RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType());
7177 return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp);
7180 // The code below only handles extension cast instructions, so far.
7182 if (LHSCI->getOpcode() != Instruction::ZExt &&
7183 LHSCI->getOpcode() != Instruction::SExt)
7186 bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
7187 bool isSignedCmp = ICI.isSignedPredicate();
7189 if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) {
7190 // Not an extension from the same type?
7191 RHSCIOp = CI->getOperand(0);
7192 if (RHSCIOp->getType() != LHSCIOp->getType())
7195 // If the signedness of the two casts doesn't agree (i.e. one is a sext
7196 // and the other is a zext), then we can't handle this.
7197 if (CI->getOpcode() != LHSCI->getOpcode())
7200 // Deal with equality cases early.
7201 if (ICI.isEquality())
7202 return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
7204 // A signed comparison of sign extended values simplifies into a
7205 // signed comparison.
7206 if (isSignedCmp && isSignedExt)
7207 return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
7209 // The other three cases all fold into an unsigned comparison.
7210 return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp);
7213 // If we aren't dealing with a constant on the RHS, exit early
7214 ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1));
7218 // Compute the constant that would happen if we truncated to SrcTy then
7219 // reextended to DestTy.
7220 Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy);
7221 Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(),
7224 // If the re-extended constant didn't change...
7226 // Make sure that sign of the Cmp and the sign of the Cast are the same.
7227 // For example, we might have:
7228 // %A = sext i16 %X to i32
7229 // %B = icmp ugt i32 %A, 1330
7230 // It is incorrect to transform this into
7231 // %B = icmp ugt i16 %X, 1330
7232 // because %A may have negative value.
7234 // However, we allow this when the compare is EQ/NE, because they are
7236 if (isSignedExt == isSignedCmp || ICI.isEquality())
7237 return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
7241 // The re-extended constant changed so the constant cannot be represented
7242 // in the shorter type. Consequently, we cannot emit a simple comparison.
7244 // First, handle some easy cases. We know the result cannot be equal at this
7245 // point so handle the ICI.isEquality() cases
7246 if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
7247 return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(*Context));
7248 if (ICI.getPredicate() == ICmpInst::ICMP_NE)
7249 return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(*Context));
7251 // Evaluate the comparison for LT (we invert for GT below). LE and GE cases
7252 // should have been folded away previously and not enter in here.
7255 // We're performing a signed comparison.
7256 if (cast<ConstantInt>(CI)->getValue().isNegative())
7257 Result = ConstantInt::getFalse(*Context); // X < (small) --> false
7259 Result = ConstantInt::getTrue(*Context); // X < (large) --> true
7261 // We're performing an unsigned comparison.
7263 // We're performing an unsigned comp with a sign extended value.
7264 // This is true if the input is >= 0. [aka >s -1]
7265 Constant *NegOne = Constant::getAllOnesValue(SrcTy);
7266 Result = Builder->CreateICmpSGT(LHSCIOp, NegOne, ICI.getName());
7268 // Unsigned extend & unsigned compare -> always true.
7269 Result = ConstantInt::getTrue(*Context);
7273 // Finally, return the value computed.
7274 if (ICI.getPredicate() == ICmpInst::ICMP_ULT ||
7275 ICI.getPredicate() == ICmpInst::ICMP_SLT)
7276 return ReplaceInstUsesWith(ICI, Result);
7278 assert((ICI.getPredicate()==ICmpInst::ICMP_UGT ||
7279 ICI.getPredicate()==ICmpInst::ICMP_SGT) &&
7280 "ICmp should be folded!");
7281 if (Constant *CI = dyn_cast<Constant>(Result))
7282 return ReplaceInstUsesWith(ICI, ConstantExpr::getNot(CI));
7283 return BinaryOperator::CreateNot(Result);
7286 Instruction *InstCombiner::visitShl(BinaryOperator &I) {
7287 return commonShiftTransforms(I);
7290 Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
7291 return commonShiftTransforms(I);
7294 Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
7295 if (Instruction *R = commonShiftTransforms(I))
7298 Value *Op0 = I.getOperand(0);
7300 // ashr int -1, X = -1 (for any arithmetic shift rights of ~0)
7301 if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
7302 if (CSI->isAllOnesValue())
7303 return ReplaceInstUsesWith(I, CSI);
7305 // See if we can turn a signed shr into an unsigned shr.
7306 if (MaskedValueIsZero(Op0,
7307 APInt::getSignBit(I.getType()->getScalarSizeInBits())))
7308 return BinaryOperator::CreateLShr(Op0, I.getOperand(1));
7310 // Arithmetic shifting an all-sign-bit value is a no-op.
7311 unsigned NumSignBits = ComputeNumSignBits(Op0);
7312 if (NumSignBits == Op0->getType()->getScalarSizeInBits())
7313 return ReplaceInstUsesWith(I, Op0);
7318 Instruction *InstCombiner::commonShiftTransforms(BinaryOperator &I) {
7319 assert(I.getOperand(1)->getType() == I.getOperand(0)->getType());
7320 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
7322 // shl X, 0 == X and shr X, 0 == X
7323 // shl 0, X == 0 and shr 0, X == 0
7324 if (Op1 == Constant::getNullValue(Op1->getType()) ||
7325 Op0 == Constant::getNullValue(Op0->getType()))
7326 return ReplaceInstUsesWith(I, Op0);
7328 if (isa<UndefValue>(Op0)) {
7329 if (I.getOpcode() == Instruction::AShr) // undef >>s X -> undef
7330 return ReplaceInstUsesWith(I, Op0);
7331 else // undef << X -> 0, undef >>u X -> 0
7332 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
7334 if (isa<UndefValue>(Op1)) {
7335 if (I.getOpcode() == Instruction::AShr) // X >>s undef -> X
7336 return ReplaceInstUsesWith(I, Op0);
7337 else // X << undef, X >>u undef -> 0
7338 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
7341 // See if we can fold away this shift.
7342 if (SimplifyDemandedInstructionBits(I))
7345 // Try to fold constant and into select arguments.
7346 if (isa<Constant>(Op0))
7347 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
7348 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
7351 if (ConstantInt *CUI = dyn_cast<ConstantInt>(Op1))
7352 if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
7357 Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
7358 BinaryOperator &I) {
7359 bool isLeftShift = I.getOpcode() == Instruction::Shl;
7361 // See if we can simplify any instructions used by the instruction whose sole
7362 // purpose is to compute bits we don't care about.
7363 uint32_t TypeBits = Op0->getType()->getScalarSizeInBits();
7365 // shl i32 X, 32 = 0 and srl i8 Y, 9 = 0, ... just don't eliminate
7368 if (Op1->uge(TypeBits)) {
7369 if (I.getOpcode() != Instruction::AShr)
7370 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
7372 I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1));
7377 // ((X*C1) << C2) == (X * (C1 << C2))
7378 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
7379 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
7380 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
7381 return BinaryOperator::CreateMul(BO->getOperand(0),
7382 ConstantExpr::getShl(BOOp, Op1));
7384 // Try to fold constant and into select arguments.
7385 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
7386 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
7388 if (isa<PHINode>(Op0))
7389 if (Instruction *NV = FoldOpIntoPhi(I))
7392 // Fold shift2(trunc(shift1(x,c1)), c2) -> trunc(shift2(shift1(x,c1),c2))
7393 if (TruncInst *TI = dyn_cast<TruncInst>(Op0)) {
7394 Instruction *TrOp = dyn_cast<Instruction>(TI->getOperand(0));
7395 // If 'shift2' is an ashr, we would have to get the sign bit into a funny
7396 // place. Don't try to do this transformation in this case. Also, we
7397 // require that the input operand is a shift-by-constant so that we have
7398 // confidence that the shifts will get folded together. We could do this
7399 // xform in more cases, but it is unlikely to be profitable.
7400 if (TrOp && I.isLogicalShift() && TrOp->isShift() &&
7401 isa<ConstantInt>(TrOp->getOperand(1))) {
7402 // Okay, we'll do this xform. Make the shift of shift.
7403 Constant *ShAmt = ConstantExpr::getZExt(Op1, TrOp->getType());
7404 // (shift2 (shift1 & 0x00FF), c2)
7405 Value *NSh = Builder->CreateBinOp(I.getOpcode(), TrOp, ShAmt,I.getName());
7407 // For logical shifts, the truncation has the effect of making the high
7408 // part of the register be zeros. Emulate this by inserting an AND to
7409 // clear the top bits as needed. This 'and' will usually be zapped by
7410 // other xforms later if dead.
7411 unsigned SrcSize = TrOp->getType()->getScalarSizeInBits();
7412 unsigned DstSize = TI->getType()->getScalarSizeInBits();
7413 APInt MaskV(APInt::getLowBitsSet(SrcSize, DstSize));
7415 // The mask we constructed says what the trunc would do if occurring
7416 // between the shifts. We want to know the effect *after* the second
7417 // shift. We know that it is a logical shift by a constant, so adjust the
7418 // mask as appropriate.
7419 if (I.getOpcode() == Instruction::Shl)
7420 MaskV <<= Op1->getZExtValue();
7422 assert(I.getOpcode() == Instruction::LShr && "Unknown logical shift");
7423 MaskV = MaskV.lshr(Op1->getZExtValue());
7427 Value *And = Builder->CreateAnd(NSh, ConstantInt::get(*Context, MaskV),
7430 // Return the value truncated to the interesting size.
7431 return new TruncInst(And, I.getType());
7435 if (Op0->hasOneUse()) {
7436 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
7437 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
7440 switch (Op0BO->getOpcode()) {
7442 case Instruction::Add:
7443 case Instruction::And:
7444 case Instruction::Or:
7445 case Instruction::Xor: {
7446 // These operators commute.
7447 // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
7448 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
7449 match(Op0BO->getOperand(1), m_Shr(m_Value(V1),
7450 m_Specific(Op1)))) {
7451 Value *YS = // (Y << C)
7452 Builder->CreateShl(Op0BO->getOperand(0), Op1, Op0BO->getName());
7454 Value *X = Builder->CreateBinOp(Op0BO->getOpcode(), YS, V1,
7455 Op0BO->getOperand(1)->getName());
7456 uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
7457 return BinaryOperator::CreateAnd(X, ConstantInt::get(*Context,
7458 APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
7461 // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
7462 Value *Op0BOOp1 = Op0BO->getOperand(1);
7463 if (isLeftShift && Op0BOOp1->hasOneUse() &&
7465 m_And(m_Shr(m_Value(V1), m_Specific(Op1)),
7466 m_ConstantInt(CC))) &&
7467 cast<BinaryOperator>(Op0BOOp1)->getOperand(0)->hasOneUse()) {
7468 Value *YS = // (Y << C)
7469 Builder->CreateShl(Op0BO->getOperand(0), Op1,
7472 Value *XM = Builder->CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
7473 V1->getName()+".mask");
7474 return BinaryOperator::Create(Op0BO->getOpcode(), YS, XM);
7479 case Instruction::Sub: {
7480 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
7481 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
7482 match(Op0BO->getOperand(0), m_Shr(m_Value(V1),
7483 m_Specific(Op1)))) {
7484 Value *YS = // (Y << C)
7485 Builder->CreateShl(Op0BO->getOperand(1), Op1, Op0BO->getName());
7487 Value *X = Builder->CreateBinOp(Op0BO->getOpcode(), V1, YS,
7488 Op0BO->getOperand(0)->getName());
7489 uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
7490 return BinaryOperator::CreateAnd(X, ConstantInt::get(*Context,
7491 APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
7494 // Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C)
7495 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
7496 match(Op0BO->getOperand(0),
7497 m_And(m_Shr(m_Value(V1), m_Value(V2)),
7498 m_ConstantInt(CC))) && V2 == Op1 &&
7499 cast<BinaryOperator>(Op0BO->getOperand(0))
7500 ->getOperand(0)->hasOneUse()) {
7501 Value *YS = // (Y << C)
7502 Builder->CreateShl(Op0BO->getOperand(1), Op1, Op0BO->getName());
7504 Value *XM = Builder->CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
7505 V1->getName()+".mask");
7507 return BinaryOperator::Create(Op0BO->getOpcode(), XM, YS);
7515 // If the operand is an bitwise operator with a constant RHS, and the
7516 // shift is the only use, we can pull it out of the shift.
7517 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
7518 bool isValid = true; // Valid only for And, Or, Xor
7519 bool highBitSet = false; // Transform if high bit of constant set?
7521 switch (Op0BO->getOpcode()) {
7522 default: isValid = false; break; // Do not perform transform!
7523 case Instruction::Add:
7524 isValid = isLeftShift;
7526 case Instruction::Or:
7527 case Instruction::Xor:
7530 case Instruction::And:
7535 // If this is a signed shift right, and the high bit is modified
7536 // by the logical operation, do not perform the transformation.
7537 // The highBitSet boolean indicates the value of the high bit of
7538 // the constant which would cause it to be modified for this
7541 if (isValid && I.getOpcode() == Instruction::AShr)
7542 isValid = Op0C->getValue()[TypeBits-1] == highBitSet;
7545 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
7548 Builder->CreateBinOp(I.getOpcode(), Op0BO->getOperand(0), Op1);
7549 NewShift->takeName(Op0BO);
7551 return BinaryOperator::Create(Op0BO->getOpcode(), NewShift,
7558 // Find out if this is a shift of a shift by a constant.
7559 BinaryOperator *ShiftOp = dyn_cast<BinaryOperator>(Op0);
7560 if (ShiftOp && !ShiftOp->isShift())
7563 if (ShiftOp && isa<ConstantInt>(ShiftOp->getOperand(1))) {
7564 ConstantInt *ShiftAmt1C = cast<ConstantInt>(ShiftOp->getOperand(1));
7565 uint32_t ShiftAmt1 = ShiftAmt1C->getLimitedValue(TypeBits);
7566 uint32_t ShiftAmt2 = Op1->getLimitedValue(TypeBits);
7567 assert(ShiftAmt2 != 0 && "Should have been simplified earlier");
7568 if (ShiftAmt1 == 0) return 0; // Will be simplified in the future.
7569 Value *X = ShiftOp->getOperand(0);
7571 uint32_t AmtSum = ShiftAmt1+ShiftAmt2; // Fold into one big shift.
7573 const IntegerType *Ty = cast<IntegerType>(I.getType());
7575 // Check for (X << c1) << c2 and (X >> c1) >> c2
7576 if (I.getOpcode() == ShiftOp->getOpcode()) {
7577 // If this is oversized composite shift, then unsigned shifts get 0, ashr
7579 if (AmtSum >= TypeBits) {
7580 if (I.getOpcode() != Instruction::AShr)
7581 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
7582 AmtSum = TypeBits-1; // Saturate to 31 for i32 ashr.
7585 return BinaryOperator::Create(I.getOpcode(), X,
7586 ConstantInt::get(Ty, AmtSum));
7589 if (ShiftOp->getOpcode() == Instruction::LShr &&
7590 I.getOpcode() == Instruction::AShr) {
7591 if (AmtSum >= TypeBits)
7592 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
7594 // ((X >>u C1) >>s C2) -> (X >>u (C1+C2)) since C1 != 0.
7595 return BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, AmtSum));
7598 if (ShiftOp->getOpcode() == Instruction::AShr &&
7599 I.getOpcode() == Instruction::LShr) {
7600 // ((X >>s C1) >>u C2) -> ((X >>s (C1+C2)) & mask) since C1 != 0.
7601 if (AmtSum >= TypeBits)
7602 AmtSum = TypeBits-1;
7604 Value *Shift = Builder->CreateAShr(X, ConstantInt::get(Ty, AmtSum));
7606 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
7607 return BinaryOperator::CreateAnd(Shift, ConstantInt::get(*Context, Mask));
7610 // Okay, if we get here, one shift must be left, and the other shift must be
7611 // right. See if the amounts are equal.
7612 if (ShiftAmt1 == ShiftAmt2) {
7613 // If we have ((X >>? C) << C), turn this into X & (-1 << C).
7614 if (I.getOpcode() == Instruction::Shl) {
7615 APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt1));
7616 return BinaryOperator::CreateAnd(X, ConstantInt::get(*Context, Mask));
7618 // If we have ((X << C) >>u C), turn this into X & (-1 >>u C).
7619 if (I.getOpcode() == Instruction::LShr) {
7620 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt1));
7621 return BinaryOperator::CreateAnd(X, ConstantInt::get(*Context, Mask));
7623 // We can simplify ((X << C) >>s C) into a trunc + sext.
7624 // NOTE: we could do this for any C, but that would make 'unusual' integer
7625 // types. For now, just stick to ones well-supported by the code
7627 const Type *SExtType = 0;
7628 switch (Ty->getBitWidth() - ShiftAmt1) {
7635 SExtType = IntegerType::get(*Context, Ty->getBitWidth() - ShiftAmt1);
7640 return new SExtInst(Builder->CreateTrunc(X, SExtType, "sext"), Ty);
7641 // Otherwise, we can't handle it yet.
7642 } else if (ShiftAmt1 < ShiftAmt2) {
7643 uint32_t ShiftDiff = ShiftAmt2-ShiftAmt1;
7645 // (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2)
7646 if (I.getOpcode() == Instruction::Shl) {
7647 assert(ShiftOp->getOpcode() == Instruction::LShr ||
7648 ShiftOp->getOpcode() == Instruction::AShr);
7649 Value *Shift = Builder->CreateShl(X, ConstantInt::get(Ty, ShiftDiff));
7651 APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
7652 return BinaryOperator::CreateAnd(Shift,
7653 ConstantInt::get(*Context, Mask));
7656 // (X << C1) >>u C2 --> X >>u (C2-C1) & (-1 >> C2)
7657 if (I.getOpcode() == Instruction::LShr) {
7658 assert(ShiftOp->getOpcode() == Instruction::Shl);
7659 Value *Shift = Builder->CreateLShr(X, ConstantInt::get(Ty, ShiftDiff));
7661 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
7662 return BinaryOperator::CreateAnd(Shift,
7663 ConstantInt::get(*Context, Mask));
7666 // We can't handle (X << C1) >>s C2, it shifts arbitrary bits in.
7668 assert(ShiftAmt2 < ShiftAmt1);
7669 uint32_t ShiftDiff = ShiftAmt1-ShiftAmt2;
7671 // (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2)
7672 if (I.getOpcode() == Instruction::Shl) {
7673 assert(ShiftOp->getOpcode() == Instruction::LShr ||
7674 ShiftOp->getOpcode() == Instruction::AShr);
7675 Value *Shift = Builder->CreateBinOp(ShiftOp->getOpcode(), X,
7676 ConstantInt::get(Ty, ShiftDiff));
7678 APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
7679 return BinaryOperator::CreateAnd(Shift,
7680 ConstantInt::get(*Context, Mask));
7683 // (X << C1) >>u C2 --> X << (C1-C2) & (-1 >> C2)
7684 if (I.getOpcode() == Instruction::LShr) {
7685 assert(ShiftOp->getOpcode() == Instruction::Shl);
7686 Value *Shift = Builder->CreateShl(X, ConstantInt::get(Ty, ShiftDiff));
7688 APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
7689 return BinaryOperator::CreateAnd(Shift,
7690 ConstantInt::get(*Context, Mask));
7693 // We can't handle (X << C1) >>a C2, it shifts arbitrary bits in.
7700 /// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
7701 /// expression. If so, decompose it, returning some value X, such that Val is
7704 static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
7705 int &Offset, LLVMContext *Context) {
7706 assert(Val->getType() == Type::getInt32Ty(*Context) &&
7707 "Unexpected allocation size type!");
7708 if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
7709 Offset = CI->getZExtValue();
7711 return ConstantInt::get(Type::getInt32Ty(*Context), 0);
7712 } else if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) {
7713 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
7714 if (I->getOpcode() == Instruction::Shl) {
7715 // This is a value scaled by '1 << the shift amt'.
7716 Scale = 1U << RHS->getZExtValue();
7718 return I->getOperand(0);
7719 } else if (I->getOpcode() == Instruction::Mul) {
7720 // This value is scaled by 'RHS'.
7721 Scale = RHS->getZExtValue();
7723 return I->getOperand(0);
7724 } else if (I->getOpcode() == Instruction::Add) {
7725 // We have X+C. Check to see if we really have (X*C2)+C1,
7726 // where C1 is divisible by C2.
7729 DecomposeSimpleLinearExpr(I->getOperand(0), SubScale,
7731 Offset += RHS->getZExtValue();
7738 // Otherwise, we can't look past this.
7745 /// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
7746 /// try to eliminate the cast by moving the type information into the alloc.
7747 Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
7748 AllocationInst &AI) {
7749 const PointerType *PTy = cast<PointerType>(CI.getType());
7751 BuilderTy AllocaBuilder(*Builder);
7752 AllocaBuilder.SetInsertPoint(AI.getParent(), &AI);
7754 // Remove any uses of AI that are dead.
7755 assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
7757 for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
7758 Instruction *User = cast<Instruction>(*UI++);
7759 if (isInstructionTriviallyDead(User)) {
7760 while (UI != E && *UI == User)
7761 ++UI; // If this instruction uses AI more than once, don't break UI.
7764 DEBUG(errs() << "IC: DCE: " << *User << '\n');
7765 EraseInstFromFunction(*User);
7769 // This requires TargetData to get the alloca alignment and size information.
7772 // Get the type really allocated and the type casted to.
7773 const Type *AllocElTy = AI.getAllocatedType();
7774 const Type *CastElTy = PTy->getElementType();
7775 if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
7777 unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy);
7778 unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy);
7779 if (CastElTyAlign < AllocElTyAlign) return 0;
7781 // If the allocation has multiple uses, only promote it if we are strictly
7782 // increasing the alignment of the resultant allocation. If we keep it the
7783 // same, we open the door to infinite loops of various kinds. (A reference
7784 // from a dbg.declare doesn't count as a use for this purpose.)
7785 if (!AI.hasOneUse() && !hasOneUsePlusDeclare(&AI) &&
7786 CastElTyAlign == AllocElTyAlign) return 0;
7788 uint64_t AllocElTySize = TD->getTypeAllocSize(AllocElTy);
7789 uint64_t CastElTySize = TD->getTypeAllocSize(CastElTy);
7790 if (CastElTySize == 0 || AllocElTySize == 0) return 0;
7792 // See if we can satisfy the modulus by pulling a scale out of the array
7794 unsigned ArraySizeScale;
7796 Value *NumElements = // See if the array size is a decomposable linear expr.
7797 DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale,
7798 ArrayOffset, Context);
7800 // If we can now satisfy the modulus, by using a non-1 scale, we really can
7802 if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
7803 (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
7805 unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
7810 Amt = ConstantInt::get(Type::getInt32Ty(*Context), Scale);
7811 // Insert before the alloca, not before the cast.
7812 Amt = AllocaBuilder.CreateMul(Amt, NumElements, "tmp");
7815 if (int Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
7816 Value *Off = ConstantInt::get(Type::getInt32Ty(*Context), Offset, true);
7817 Amt = AllocaBuilder.CreateAdd(Amt, Off, "tmp");
7820 AllocationInst *New = AllocaBuilder.CreateAlloca(CastElTy, Amt);
7821 New->setAlignment(AI.getAlignment());
7824 // If the allocation has one real use plus a dbg.declare, just remove the
7826 if (DbgDeclareInst *DI = hasOneUsePlusDeclare(&AI)) {
7827 EraseInstFromFunction(*DI);
7829 // If the allocation has multiple real uses, insert a cast and change all
7830 // things that used it to use the new cast. This will also hack on CI, but it
7832 else if (!AI.hasOneUse()) {
7833 // New is the allocation instruction, pointer typed. AI is the original
7834 // allocation instruction, also pointer typed. Thus, cast to use is BitCast.
7835 Value *NewCast = AllocaBuilder.CreateBitCast(New, AI.getType(), "tmpcast");
7836 AI.replaceAllUsesWith(NewCast);
7838 return ReplaceInstUsesWith(CI, New);
7841 /// CanEvaluateInDifferentType - Return true if we can take the specified value
7842 /// and return it as type Ty without inserting any new casts and without
7843 /// changing the computed value. This is used by code that tries to decide
7844 /// whether promoting or shrinking integer operations to wider or smaller types
7845 /// will allow us to eliminate a truncate or extend.
7847 /// This is a truncation operation if Ty is smaller than V->getType(), or an
7848 /// extension operation if Ty is larger.
7850 /// If CastOpc is a truncation, then Ty will be a type smaller than V. We
7851 /// should return true if trunc(V) can be computed by computing V in the smaller
7852 /// type. If V is an instruction, then trunc(inst(x,y)) can be computed as
7853 /// inst(trunc(x),trunc(y)), which only makes sense if x and y can be
7854 /// efficiently truncated.
7856 /// If CastOpc is a sext or zext, we are asking if the low bits of the value can
7857 /// bit computed in a larger type, which is then and'd or sext_in_reg'd to get
7858 /// the final result.
7859 bool InstCombiner::CanEvaluateInDifferentType(Value *V, const Type *Ty,
7861 int &NumCastsRemoved){
7862 // We can always evaluate constants in another type.
7863 if (isa<Constant>(V))
7866 Instruction *I = dyn_cast<Instruction>(V);
7867 if (!I) return false;
7869 const Type *OrigTy = V->getType();
7871 // If this is an extension or truncate, we can often eliminate it.
7872 if (isa<TruncInst>(I) || isa<ZExtInst>(I) || isa<SExtInst>(I)) {
7873 // If this is a cast from the destination type, we can trivially eliminate
7874 // it, and this will remove a cast overall.
7875 if (I->getOperand(0)->getType() == Ty) {
7876 // If the first operand is itself a cast, and is eliminable, do not count
7877 // this as an eliminable cast. We would prefer to eliminate those two
7879 if (!isa<CastInst>(I->getOperand(0)) && I->hasOneUse())
7885 // We can't extend or shrink something that has multiple uses: doing so would
7886 // require duplicating the instruction in general, which isn't profitable.
7887 if (!I->hasOneUse()) return false;
7889 unsigned Opc = I->getOpcode();
7891 case Instruction::Add:
7892 case Instruction::Sub:
7893 case Instruction::Mul:
7894 case Instruction::And:
7895 case Instruction::Or:
7896 case Instruction::Xor:
7897 // These operators can all arbitrarily be extended or truncated.
7898 return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
7900 CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
7903 case Instruction::UDiv:
7904 case Instruction::URem: {
7905 // UDiv and URem can be truncated if all the truncated bits are zero.
7906 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
7907 uint32_t BitWidth = Ty->getScalarSizeInBits();
7908 if (BitWidth < OrigBitWidth) {
7909 APInt Mask = APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth);
7910 if (MaskedValueIsZero(I->getOperand(0), Mask) &&
7911 MaskedValueIsZero(I->getOperand(1), Mask)) {
7912 return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
7914 CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
7920 case Instruction::Shl:
7921 // If we are truncating the result of this SHL, and if it's a shift of a
7922 // constant amount, we can always perform a SHL in a smaller type.
7923 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
7924 uint32_t BitWidth = Ty->getScalarSizeInBits();
7925 if (BitWidth < OrigTy->getScalarSizeInBits() &&
7926 CI->getLimitedValue(BitWidth) < BitWidth)
7927 return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
7931 case Instruction::LShr:
7932 // If this is a truncate of a logical shr, we can truncate it to a smaller
7933 // lshr iff we know that the bits we would otherwise be shifting in are
7935 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
7936 uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
7937 uint32_t BitWidth = Ty->getScalarSizeInBits();
7938 if (BitWidth < OrigBitWidth &&
7939 MaskedValueIsZero(I->getOperand(0),
7940 APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
7941 CI->getLimitedValue(BitWidth) < BitWidth) {
7942 return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
7947 case Instruction::ZExt:
7948 case Instruction::SExt:
7949 case Instruction::Trunc:
7950 // If this is the same kind of case as our original (e.g. zext+zext), we
7951 // can safely replace it. Note that replacing it does not reduce the number
7952 // of casts in the input.
7956 // sext (zext ty1), ty2 -> zext ty2
7957 if (CastOpc == Instruction::SExt && Opc == Instruction::ZExt)
7960 case Instruction::Select: {
7961 SelectInst *SI = cast<SelectInst>(I);
7962 return CanEvaluateInDifferentType(SI->getTrueValue(), Ty, CastOpc,
7964 CanEvaluateInDifferentType(SI->getFalseValue(), Ty, CastOpc,
7967 case Instruction::PHI: {
7968 // We can change a phi if we can change all operands.
7969 PHINode *PN = cast<PHINode>(I);
7970 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
7971 if (!CanEvaluateInDifferentType(PN->getIncomingValue(i), Ty, CastOpc,
7977 // TODO: Can handle more cases here.
7984 /// EvaluateInDifferentType - Given an expression that
7985 /// CanEvaluateInDifferentType returns true for, actually insert the code to
7986 /// evaluate the expression.
7987 Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
7989 if (Constant *C = dyn_cast<Constant>(V))
7990 return ConstantExpr::getIntegerCast(C, Ty,
7991 isSigned /*Sext or ZExt*/);
7993 // Otherwise, it must be an instruction.
7994 Instruction *I = cast<Instruction>(V);
7995 Instruction *Res = 0;
7996 unsigned Opc = I->getOpcode();
7998 case Instruction::Add:
7999 case Instruction::Sub:
8000 case Instruction::Mul:
8001 case Instruction::And:
8002 case Instruction::Or:
8003 case Instruction::Xor:
8004 case Instruction::AShr:
8005 case Instruction::LShr:
8006 case Instruction::Shl:
8007 case Instruction::UDiv:
8008 case Instruction::URem: {
8009 Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
8010 Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
8011 Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
8014 case Instruction::Trunc:
8015 case Instruction::ZExt:
8016 case Instruction::SExt:
8017 // If the source type of the cast is the type we're trying for then we can
8018 // just return the source. There's no need to insert it because it is not
8020 if (I->getOperand(0)->getType() == Ty)
8021 return I->getOperand(0);
8023 // Otherwise, must be the same type of cast, so just reinsert a new one.
8024 Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),
8027 case Instruction::Select: {
8028 Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
8029 Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
8030 Res = SelectInst::Create(I->getOperand(0), True, False);
8033 case Instruction::PHI: {
8034 PHINode *OPN = cast<PHINode>(I);
8035 PHINode *NPN = PHINode::Create(Ty);
8036 for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
8037 Value *V =EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned);
8038 NPN->addIncoming(V, OPN->getIncomingBlock(i));
8044 // TODO: Can handle more cases here.
8045 llvm_unreachable("Unreachable!");
8050 return InsertNewInstBefore(Res, *I);
8053 /// @brief Implement the transforms common to all CastInst visitors.
8054 Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
8055 Value *Src = CI.getOperand(0);
8057 // Many cases of "cast of a cast" are eliminable. If it's eliminable we just
8058 // eliminate it now.
8059 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
8060 if (Instruction::CastOps opc =
8061 isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) {
8062 // The first cast (CSrc) is eliminable so we need to fix up or replace
8063 // the second cast (CI). CSrc will then have a good chance of being dead.
8064 return CastInst::Create(opc, CSrc->getOperand(0), CI.getType());
8068 // If we are casting a select then fold the cast into the select
8069 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
8070 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
8073 // If we are casting a PHI then fold the cast into the PHI
8074 if (isa<PHINode>(Src))
8075 if (Instruction *NV = FoldOpIntoPhi(CI))
8081 /// FindElementAtOffset - Given a type and a constant offset, determine whether
8082 /// or not there is a sequence of GEP indices into the type that will land us at
8083 /// the specified offset. If so, fill them into NewIndices and return the
8084 /// resultant element type, otherwise return null.
8085 static const Type *FindElementAtOffset(const Type *Ty, int64_t Offset,
8086 SmallVectorImpl<Value*> &NewIndices,
8087 const TargetData *TD,
8088 LLVMContext *Context) {
8090 if (!Ty->isSized()) return 0;
8092 // Start with the index over the outer type. Note that the type size
8093 // might be zero (even if the offset isn't zero) if the indexed type
8094 // is something like [0 x {int, int}]
8095 const Type *IntPtrTy = TD->getIntPtrType(*Context);
8096 int64_t FirstIdx = 0;
8097 if (int64_t TySize = TD->getTypeAllocSize(Ty)) {
8098 FirstIdx = Offset/TySize;
8099 Offset -= FirstIdx*TySize;
8101 // Handle hosts where % returns negative instead of values [0..TySize).
8105 assert(Offset >= 0);
8107 assert((uint64_t)Offset < (uint64_t)TySize && "Out of range offset");
8110 NewIndices.push_back(ConstantInt::get(IntPtrTy, FirstIdx));
8112 // Index into the types. If we fail, set OrigBase to null.
8114 // Indexing into tail padding between struct/array elements.
8115 if (uint64_t(Offset*8) >= TD->getTypeSizeInBits(Ty))
8118 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
8119 const StructLayout *SL = TD->getStructLayout(STy);
8120 assert(Offset < (int64_t)SL->getSizeInBytes() &&
8121 "Offset must stay within the indexed type");
8123 unsigned Elt = SL->getElementContainingOffset(Offset);
8124 NewIndices.push_back(ConstantInt::get(Type::getInt32Ty(*Context), Elt));
8126 Offset -= SL->getElementOffset(Elt);
8127 Ty = STy->getElementType(Elt);
8128 } else if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) {
8129 uint64_t EltSize = TD->getTypeAllocSize(AT->getElementType());
8130 assert(EltSize && "Cannot index into a zero-sized array");
8131 NewIndices.push_back(ConstantInt::get(IntPtrTy,Offset/EltSize));
8133 Ty = AT->getElementType();
8135 // Otherwise, we can't index into the middle of this atomic type, bail.
8143 /// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint)
8144 Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
8145 Value *Src = CI.getOperand(0);
8147 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
8148 // If casting the result of a getelementptr instruction with no offset, turn
8149 // this into a cast of the original pointer!
8150 if (GEP->hasAllZeroIndices()) {
8151 // Changing the cast operand is usually not a good idea but it is safe
8152 // here because the pointer operand is being replaced with another
8153 // pointer operand so the opcode doesn't need to change.
8155 CI.setOperand(0, GEP->getOperand(0));
8159 // If the GEP has a single use, and the base pointer is a bitcast, and the
8160 // GEP computes a constant offset, see if we can convert these three
8161 // instructions into fewer. This typically happens with unions and other
8162 // non-type-safe code.
8163 if (TD && GEP->hasOneUse() && isa<BitCastInst>(GEP->getOperand(0))) {
8164 if (GEP->hasAllConstantIndices()) {
8165 // We are guaranteed to get a constant from EmitGEPOffset.
8166 ConstantInt *OffsetV =
8167 cast<ConstantInt>(EmitGEPOffset(GEP, CI, *this));
8168 int64_t Offset = OffsetV->getSExtValue();
8170 // Get the base pointer input of the bitcast, and the type it points to.
8171 Value *OrigBase = cast<BitCastInst>(GEP->getOperand(0))->getOperand(0);
8172 const Type *GEPIdxTy =
8173 cast<PointerType>(OrigBase->getType())->getElementType();
8174 SmallVector<Value*, 8> NewIndices;
8175 if (FindElementAtOffset(GEPIdxTy, Offset, NewIndices, TD, Context)) {
8176 // If we were able to index down into an element, create the GEP
8177 // and bitcast the result. This eliminates one bitcast, potentially
8179 Value *NGEP = cast<GEPOperator>(GEP)->isInBounds() ?
8180 Builder->CreateInBoundsGEP(OrigBase,
8181 NewIndices.begin(), NewIndices.end()) :
8182 Builder->CreateGEP(OrigBase, NewIndices.begin(), NewIndices.end());
8183 NGEP->takeName(GEP);
8185 if (isa<BitCastInst>(CI))
8186 return new BitCastInst(NGEP, CI.getType());
8187 assert(isa<PtrToIntInst>(CI));
8188 return new PtrToIntInst(NGEP, CI.getType());
8194 return commonCastTransforms(CI);
8197 /// isSafeIntegerType - Return true if this is a basic integer type, not a crazy
8198 /// type like i42. We don't want to introduce operations on random non-legal
8199 /// integer types where they don't already exist in the code. In the future,
8200 /// we should consider making this based off target-data, so that 32-bit targets
8201 /// won't get i64 operations etc.
8202 static bool isSafeIntegerType(const Type *Ty) {
8203 switch (Ty->getPrimitiveSizeInBits()) {
8214 /// commonIntCastTransforms - This function implements the common transforms
8215 /// for trunc, zext, and sext.
8216 Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
8217 if (Instruction *Result = commonCastTransforms(CI))
8220 Value *Src = CI.getOperand(0);
8221 const Type *SrcTy = Src->getType();
8222 const Type *DestTy = CI.getType();
8223 uint32_t SrcBitSize = SrcTy->getScalarSizeInBits();
8224 uint32_t DestBitSize = DestTy->getScalarSizeInBits();
8226 // See if we can simplify any instructions used by the LHS whose sole
8227 // purpose is to compute bits we don't care about.
8228 if (SimplifyDemandedInstructionBits(CI))
8231 // If the source isn't an instruction or has more than one use then we
8232 // can't do anything more.
8233 Instruction *SrcI = dyn_cast<Instruction>(Src);
8234 if (!SrcI || !Src->hasOneUse())
8237 // Attempt to propagate the cast into the instruction for int->int casts.
8238 int NumCastsRemoved = 0;
8239 // Only do this if the dest type is a simple type, don't convert the
8240 // expression tree to something weird like i93 unless the source is also
8242 if ((isSafeIntegerType(DestTy->getScalarType()) ||
8243 !isSafeIntegerType(SrcI->getType()->getScalarType())) &&
8244 CanEvaluateInDifferentType(SrcI, DestTy,
8245 CI.getOpcode(), NumCastsRemoved)) {
8246 // If this cast is a truncate, evaluting in a different type always
8247 // eliminates the cast, so it is always a win. If this is a zero-extension,
8248 // we need to do an AND to maintain the clear top-part of the computation,
8249 // so we require that the input have eliminated at least one cast. If this
8250 // is a sign extension, we insert two new casts (to do the extension) so we
8251 // require that two casts have been eliminated.
8252 bool DoXForm = false;
8253 bool JustReplace = false;
8254 switch (CI.getOpcode()) {
8256 // All the others use floating point so we shouldn't actually
8257 // get here because of the check above.
8258 llvm_unreachable("Unknown cast type");
8259 case Instruction::Trunc:
8262 case Instruction::ZExt: {
8263 DoXForm = NumCastsRemoved >= 1;
8264 if (!DoXForm && 0) {
8265 // If it's unnecessary to issue an AND to clear the high bits, it's
8266 // always profitable to do this xform.
8267 Value *TryRes = EvaluateInDifferentType(SrcI, DestTy, false);
8268 APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize));
8269 if (MaskedValueIsZero(TryRes, Mask))
8270 return ReplaceInstUsesWith(CI, TryRes);
8272 if (Instruction *TryI = dyn_cast<Instruction>(TryRes))
8273 if (TryI->use_empty())
8274 EraseInstFromFunction(*TryI);
8278 case Instruction::SExt: {
8279 DoXForm = NumCastsRemoved >= 2;
8280 if (!DoXForm && !isa<TruncInst>(SrcI) && 0) {
8281 // If we do not have to emit the truncate + sext pair, then it's always
8282 // profitable to do this xform.
8284 // It's not safe to eliminate the trunc + sext pair if one of the
8285 // eliminated cast is a truncate. e.g.
8286 // t2 = trunc i32 t1 to i16
8287 // t3 = sext i16 t2 to i32
8290 Value *TryRes = EvaluateInDifferentType(SrcI, DestTy, true);
8291 unsigned NumSignBits = ComputeNumSignBits(TryRes);
8292 if (NumSignBits > (DestBitSize - SrcBitSize))
8293 return ReplaceInstUsesWith(CI, TryRes);
8295 if (Instruction *TryI = dyn_cast<Instruction>(TryRes))
8296 if (TryI->use_empty())
8297 EraseInstFromFunction(*TryI);
8304 DEBUG(errs() << "ICE: EvaluateInDifferentType converting expression type"
8305 " to avoid cast: " << CI);
8306 Value *Res = EvaluateInDifferentType(SrcI, DestTy,
8307 CI.getOpcode() == Instruction::SExt);
8309 // Just replace this cast with the result.
8310 return ReplaceInstUsesWith(CI, Res);
8312 assert(Res->getType() == DestTy);
8313 switch (CI.getOpcode()) {
8314 default: llvm_unreachable("Unknown cast type!");
8315 case Instruction::Trunc:
8316 // Just replace this cast with the result.
8317 return ReplaceInstUsesWith(CI, Res);
8318 case Instruction::ZExt: {
8319 assert(SrcBitSize < DestBitSize && "Not a zext?");
8321 // If the high bits are already zero, just replace this cast with the
8323 APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize));
8324 if (MaskedValueIsZero(Res, Mask))
8325 return ReplaceInstUsesWith(CI, Res);
8327 // We need to emit an AND to clear the high bits.
8328 Constant *C = ConstantInt::get(*Context,
8329 APInt::getLowBitsSet(DestBitSize, SrcBitSize));
8330 return BinaryOperator::CreateAnd(Res, C);
8332 case Instruction::SExt: {
8333 // If the high bits are already filled with sign bit, just replace this
8334 // cast with the result.
8335 unsigned NumSignBits = ComputeNumSignBits(Res);
8336 if (NumSignBits > (DestBitSize - SrcBitSize))
8337 return ReplaceInstUsesWith(CI, Res);
8339 // We need to emit a cast to truncate, then a cast to sext.
8340 return new SExtInst(Builder->CreateTrunc(Res, Src->getType()), DestTy);
8346 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
8347 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
8349 switch (SrcI->getOpcode()) {
8350 case Instruction::Add:
8351 case Instruction::Mul:
8352 case Instruction::And:
8353 case Instruction::Or:
8354 case Instruction::Xor:
8355 // If we are discarding information, rewrite.
8356 if (DestBitSize < SrcBitSize && DestBitSize != 1) {
8357 // Don't insert two casts unless at least one can be eliminated.
8358 if (!ValueRequiresCast(CI.getOpcode(), Op1, DestTy, TD) ||
8359 !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
8360 Value *Op0c = Builder->CreateTrunc(Op0, DestTy, Op0->getName());
8361 Value *Op1c = Builder->CreateTrunc(Op1, DestTy, Op1->getName());
8362 return BinaryOperator::Create(
8363 cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
8367 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
8368 if (isa<ZExtInst>(CI) && SrcBitSize == 1 &&
8369 SrcI->getOpcode() == Instruction::Xor &&
8370 Op1 == ConstantInt::getTrue(*Context) &&
8371 (!Op0->hasOneUse() || !isa<CmpInst>(Op0))) {
8372 Value *New = Builder->CreateZExt(Op0, DestTy, Op0->getName());
8373 return BinaryOperator::CreateXor(New,
8374 ConstantInt::get(CI.getType(), 1));
8378 case Instruction::Shl: {
8379 // Canonicalize trunc inside shl, if we can.
8380 ConstantInt *CI = dyn_cast<ConstantInt>(Op1);
8381 if (CI && DestBitSize < SrcBitSize &&
8382 CI->getLimitedValue(DestBitSize) < DestBitSize) {
8383 Value *Op0c = Builder->CreateTrunc(Op0, DestTy, Op0->getName());
8384 Value *Op1c = Builder->CreateTrunc(Op1, DestTy, Op1->getName());
8385 return BinaryOperator::CreateShl(Op0c, Op1c);
8393 Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
8394 if (Instruction *Result = commonIntCastTransforms(CI))
8397 Value *Src = CI.getOperand(0);
8398 const Type *Ty = CI.getType();
8399 uint32_t DestBitWidth = Ty->getScalarSizeInBits();
8400 uint32_t SrcBitWidth = Src->getType()->getScalarSizeInBits();
8402 // Canonicalize trunc x to i1 -> (icmp ne (and x, 1), 0)
8403 if (DestBitWidth == 1) {
8404 Constant *One = ConstantInt::get(Src->getType(), 1);
8405 Src = Builder->CreateAnd(Src, One, "tmp");
8406 Value *Zero = Constant::getNullValue(Src->getType());
8407 return new ICmpInst(ICmpInst::ICMP_NE, Src, Zero);
8410 // Optimize trunc(lshr(), c) to pull the shift through the truncate.
8411 ConstantInt *ShAmtV = 0;
8413 if (Src->hasOneUse() &&
8414 match(Src, m_LShr(m_Value(ShiftOp), m_ConstantInt(ShAmtV)))) {
8415 uint32_t ShAmt = ShAmtV->getLimitedValue(SrcBitWidth);
8417 // Get a mask for the bits shifting in.
8418 APInt Mask(APInt::getLowBitsSet(SrcBitWidth, ShAmt).shl(DestBitWidth));
8419 if (MaskedValueIsZero(ShiftOp, Mask)) {
8420 if (ShAmt >= DestBitWidth) // All zeros.
8421 return ReplaceInstUsesWith(CI, Constant::getNullValue(Ty));
8423 // Okay, we can shrink this. Truncate the input, then return a new
8425 Value *V1 = Builder->CreateTrunc(ShiftOp, Ty, ShiftOp->getName());
8426 Value *V2 = ConstantExpr::getTrunc(ShAmtV, Ty);
8427 return BinaryOperator::CreateLShr(V1, V2);
8434 /// transformZExtICmp - Transform (zext icmp) to bitwise / integer operations
8435 /// in order to eliminate the icmp.
8436 Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, Instruction &CI,
8438 // If we are just checking for a icmp eq of a single bit and zext'ing it
8439 // to an integer, then shift the bit to the appropriate place and then
8440 // cast to integer to avoid the comparison.
8441 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
8442 const APInt &Op1CV = Op1C->getValue();
8444 // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
8445 // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
8446 if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
8447 (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())) {
8448 if (!DoXform) return ICI;
8450 Value *In = ICI->getOperand(0);
8451 Value *Sh = ConstantInt::get(In->getType(),
8452 In->getType()->getScalarSizeInBits()-1);
8453 In = Builder->CreateLShr(In, Sh, In->getName()+".lobit");
8454 if (In->getType() != CI.getType())
8455 In = Builder->CreateIntCast(In, CI.getType(), false/*ZExt*/, "tmp");
8457 if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
8458 Constant *One = ConstantInt::get(In->getType(), 1);
8459 In = Builder->CreateXor(In, One, In->getName()+".not");
8462 return ReplaceInstUsesWith(CI, In);
8467 // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
8468 // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
8469 // zext (X == 1) to i32 --> X iff X has only the low bit set.
8470 // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
8471 // zext (X != 0) to i32 --> X iff X has only the low bit set.
8472 // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
8473 // zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
8474 // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
8475 if ((Op1CV == 0 || Op1CV.isPowerOf2()) &&
8476 // This only works for EQ and NE
8477 ICI->isEquality()) {
8478 // If Op1C some other power of two, convert:
8479 uint32_t BitWidth = Op1C->getType()->getBitWidth();
8480 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
8481 APInt TypeMask(APInt::getAllOnesValue(BitWidth));
8482 ComputeMaskedBits(ICI->getOperand(0), TypeMask, KnownZero, KnownOne);
8484 APInt KnownZeroMask(~KnownZero);
8485 if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
8486 if (!DoXform) return ICI;
8488 bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
8489 if (Op1CV != 0 && (Op1CV != KnownZeroMask)) {
8490 // (X&4) == 2 --> false
8491 // (X&4) != 2 --> true
8492 Constant *Res = ConstantInt::get(Type::getInt1Ty(*Context), isNE);
8493 Res = ConstantExpr::getZExt(Res, CI.getType());
8494 return ReplaceInstUsesWith(CI, Res);
8497 uint32_t ShiftAmt = KnownZeroMask.logBase2();
8498 Value *In = ICI->getOperand(0);
8500 // Perform a logical shr by shiftamt.
8501 // Insert the shift to put the result in the low bit.
8502 In = Builder->CreateLShr(In, ConstantInt::get(In->getType(),ShiftAmt),
8503 In->getName()+".lobit");
8506 if ((Op1CV != 0) == isNE) { // Toggle the low bit.
8507 Constant *One = ConstantInt::get(In->getType(), 1);
8508 In = Builder->CreateXor(In, One, "tmp");
8511 if (CI.getType() == In->getType())
8512 return ReplaceInstUsesWith(CI, In);
8514 return CastInst::CreateIntegerCast(In, CI.getType(), false/*ZExt*/);
8522 Instruction *InstCombiner::visitZExt(ZExtInst &CI) {
8523 // If one of the common conversion will work ..
8524 if (Instruction *Result = commonIntCastTransforms(CI))
8527 Value *Src = CI.getOperand(0);
8529 // If this is a TRUNC followed by a ZEXT then we are dealing with integral
8530 // types and if the sizes are just right we can convert this into a logical
8531 // 'and' which will be much cheaper than the pair of casts.
8532 if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) { // A->B->C cast
8533 // Get the sizes of the types involved. We know that the intermediate type
8534 // will be smaller than A or C, but don't know the relation between A and C.
8535 Value *A = CSrc->getOperand(0);
8536 unsigned SrcSize = A->getType()->getScalarSizeInBits();
8537 unsigned MidSize = CSrc->getType()->getScalarSizeInBits();
8538 unsigned DstSize = CI.getType()->getScalarSizeInBits();
8539 // If we're actually extending zero bits, then if
8540 // SrcSize < DstSize: zext(a & mask)
8541 // SrcSize == DstSize: a & mask
8542 // SrcSize > DstSize: trunc(a) & mask
8543 if (SrcSize < DstSize) {
8544 APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
8545 Constant *AndConst = ConstantInt::get(A->getType(), AndValue);
8546 Value *And = Builder->CreateAnd(A, AndConst, CSrc->getName()+".mask");
8547 return new ZExtInst(And, CI.getType());
8550 if (SrcSize == DstSize) {
8551 APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
8552 return BinaryOperator::CreateAnd(A, ConstantInt::get(A->getType(),
8555 if (SrcSize > DstSize) {
8556 Value *Trunc = Builder->CreateTrunc(A, CI.getType(), "tmp");
8557 APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize));
8558 return BinaryOperator::CreateAnd(Trunc,
8559 ConstantInt::get(Trunc->getType(),
8564 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
8565 return transformZExtICmp(ICI, CI);
8567 BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src);
8568 if (SrcI && SrcI->getOpcode() == Instruction::Or) {
8569 // zext (or icmp, icmp) --> or (zext icmp), (zext icmp) if at least one
8570 // of the (zext icmp) will be transformed.
8571 ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0));
8572 ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1));
8573 if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() &&
8574 (transformZExtICmp(LHS, CI, false) ||
8575 transformZExtICmp(RHS, CI, false))) {
8576 Value *LCast = Builder->CreateZExt(LHS, CI.getType(), LHS->getName());
8577 Value *RCast = Builder->CreateZExt(RHS, CI.getType(), RHS->getName());
8578 return BinaryOperator::Create(Instruction::Or, LCast, RCast);
8582 // zext(trunc(t) & C) -> (t & zext(C)).
8583 if (SrcI && SrcI->getOpcode() == Instruction::And && SrcI->hasOneUse())
8584 if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1)))
8585 if (TruncInst *TI = dyn_cast<TruncInst>(SrcI->getOperand(0))) {
8586 Value *TI0 = TI->getOperand(0);
8587 if (TI0->getType() == CI.getType())
8589 BinaryOperator::CreateAnd(TI0,
8590 ConstantExpr::getZExt(C, CI.getType()));
8593 // zext((trunc(t) & C) ^ C) -> ((t & zext(C)) ^ zext(C)).
8594 if (SrcI && SrcI->getOpcode() == Instruction::Xor && SrcI->hasOneUse())
8595 if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1)))
8596 if (BinaryOperator *And = dyn_cast<BinaryOperator>(SrcI->getOperand(0)))
8597 if (And->getOpcode() == Instruction::And && And->hasOneUse() &&
8598 And->getOperand(1) == C)
8599 if (TruncInst *TI = dyn_cast<TruncInst>(And->getOperand(0))) {
8600 Value *TI0 = TI->getOperand(0);
8601 if (TI0->getType() == CI.getType()) {
8602 Constant *ZC = ConstantExpr::getZExt(C, CI.getType());
8603 Value *NewAnd = Builder->CreateAnd(TI0, ZC, "tmp");
8604 return BinaryOperator::CreateXor(NewAnd, ZC);
8611 Instruction *InstCombiner::visitSExt(SExtInst &CI) {
8612 if (Instruction *I = commonIntCastTransforms(CI))
8615 Value *Src = CI.getOperand(0);
8617 // Canonicalize sign-extend from i1 to a select.
8618 if (Src->getType() == Type::getInt1Ty(*Context))
8619 return SelectInst::Create(Src,
8620 Constant::getAllOnesValue(CI.getType()),
8621 Constant::getNullValue(CI.getType()));
8623 // See if the value being truncated is already sign extended. If so, just
8624 // eliminate the trunc/sext pair.
8625 if (Operator::getOpcode(Src) == Instruction::Trunc) {
8626 Value *Op = cast<User>(Src)->getOperand(0);
8627 unsigned OpBits = Op->getType()->getScalarSizeInBits();
8628 unsigned MidBits = Src->getType()->getScalarSizeInBits();
8629 unsigned DestBits = CI.getType()->getScalarSizeInBits();
8630 unsigned NumSignBits = ComputeNumSignBits(Op);
8632 if (OpBits == DestBits) {
8633 // Op is i32, Mid is i8, and Dest is i32. If Op has more than 24 sign
8634 // bits, it is already ready.
8635 if (NumSignBits > DestBits-MidBits)
8636 return ReplaceInstUsesWith(CI, Op);
8637 } else if (OpBits < DestBits) {
8638 // Op is i32, Mid is i8, and Dest is i64. If Op has more than 24 sign
8639 // bits, just sext from i32.
8640 if (NumSignBits > OpBits-MidBits)
8641 return new SExtInst(Op, CI.getType(), "tmp");
8643 // Op is i64, Mid is i8, and Dest is i32. If Op has more than 56 sign
8644 // bits, just truncate to i32.
8645 if (NumSignBits > OpBits-MidBits)
8646 return new TruncInst(Op, CI.getType(), "tmp");
8650 // If the input is a shl/ashr pair of a same constant, then this is a sign
8651 // extension from a smaller value. If we could trust arbitrary bitwidth
8652 // integers, we could turn this into a truncate to the smaller bit and then
8653 // use a sext for the whole extension. Since we don't, look deeper and check
8654 // for a truncate. If the source and dest are the same type, eliminate the
8655 // trunc and extend and just do shifts. For example, turn:
8656 // %a = trunc i32 %i to i8
8657 // %b = shl i8 %a, 6
8658 // %c = ashr i8 %b, 6
8659 // %d = sext i8 %c to i32
8661 // %a = shl i32 %i, 30
8662 // %d = ashr i32 %a, 30
8664 ConstantInt *BA = 0, *CA = 0;
8665 if (match(Src, m_AShr(m_Shl(m_Value(A), m_ConstantInt(BA)),
8666 m_ConstantInt(CA))) &&
8667 BA == CA && isa<TruncInst>(A)) {
8668 Value *I = cast<TruncInst>(A)->getOperand(0);
8669 if (I->getType() == CI.getType()) {
8670 unsigned MidSize = Src->getType()->getScalarSizeInBits();
8671 unsigned SrcDstSize = CI.getType()->getScalarSizeInBits();
8672 unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize;
8673 Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt);
8674 I = Builder->CreateShl(I, ShAmtV, CI.getName());
8675 return BinaryOperator::CreateAShr(I, ShAmtV);
8682 /// FitsInFPType - Return a Constant* for the specified FP constant if it fits
8683 /// in the specified FP type without changing its value.
8684 static Constant *FitsInFPType(ConstantFP *CFP, const fltSemantics &Sem,
8685 LLVMContext *Context) {
8687 APFloat F = CFP->getValueAPF();
8688 (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo);
8690 return ConstantFP::get(*Context, F);
8694 /// LookThroughFPExtensions - If this is an fp extension instruction, look
8695 /// through it until we get the source value.
8696 static Value *LookThroughFPExtensions(Value *V, LLVMContext *Context) {
8697 if (Instruction *I = dyn_cast<Instruction>(V))
8698 if (I->getOpcode() == Instruction::FPExt)
8699 return LookThroughFPExtensions(I->getOperand(0), Context);
8701 // If this value is a constant, return the constant in the smallest FP type
8702 // that can accurately represent it. This allows us to turn
8703 // (float)((double)X+2.0) into x+2.0f.
8704 if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
8705 if (CFP->getType() == Type::getPPC_FP128Ty(*Context))
8706 return V; // No constant folding of this.
8707 // See if the value can be truncated to float and then reextended.
8708 if (Value *V = FitsInFPType(CFP, APFloat::IEEEsingle, Context))
8710 if (CFP->getType() == Type::getDoubleTy(*Context))
8711 return V; // Won't shrink.
8712 if (Value *V = FitsInFPType(CFP, APFloat::IEEEdouble, Context))
8714 // Don't try to shrink to various long double types.
8720 Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) {
8721 if (Instruction *I = commonCastTransforms(CI))
8724 // If we have fptrunc(fadd (fpextend x), (fpextend y)), where x and y are
8725 // smaller than the destination type, we can eliminate the truncate by doing
8726 // the add as the smaller type. This applies to fadd/fsub/fmul/fdiv as well as
8727 // many builtins (sqrt, etc).
8728 BinaryOperator *OpI = dyn_cast<BinaryOperator>(CI.getOperand(0));
8729 if (OpI && OpI->hasOneUse()) {
8730 switch (OpI->getOpcode()) {
8732 case Instruction::FAdd:
8733 case Instruction::FSub:
8734 case Instruction::FMul:
8735 case Instruction::FDiv:
8736 case Instruction::FRem:
8737 const Type *SrcTy = OpI->getType();
8738 Value *LHSTrunc = LookThroughFPExtensions(OpI->getOperand(0), Context);
8739 Value *RHSTrunc = LookThroughFPExtensions(OpI->getOperand(1), Context);
8740 if (LHSTrunc->getType() != SrcTy &&
8741 RHSTrunc->getType() != SrcTy) {
8742 unsigned DstSize = CI.getType()->getScalarSizeInBits();
8743 // If the source types were both smaller than the destination type of
8744 // the cast, do this xform.
8745 if (LHSTrunc->getType()->getScalarSizeInBits() <= DstSize &&
8746 RHSTrunc->getType()->getScalarSizeInBits() <= DstSize) {
8747 LHSTrunc = Builder->CreateFPExt(LHSTrunc, CI.getType());
8748 RHSTrunc = Builder->CreateFPExt(RHSTrunc, CI.getType());
8749 return BinaryOperator::Create(OpI->getOpcode(), LHSTrunc, RHSTrunc);
8758 Instruction *InstCombiner::visitFPExt(CastInst &CI) {
8759 return commonCastTransforms(CI);
8762 Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) {
8763 Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
8765 return commonCastTransforms(FI);
8767 // fptoui(uitofp(X)) --> X
8768 // fptoui(sitofp(X)) --> X
8769 // This is safe if the intermediate type has enough bits in its mantissa to
8770 // accurately represent all values of X. For example, do not do this with
8771 // i64->float->i64. This is also safe for sitofp case, because any negative
8772 // 'X' value would cause an undefined result for the fptoui.
8773 if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
8774 OpI->getOperand(0)->getType() == FI.getType() &&
8775 (int)FI.getType()->getScalarSizeInBits() < /*extra bit for sign */
8776 OpI->getType()->getFPMantissaWidth())
8777 return ReplaceInstUsesWith(FI, OpI->getOperand(0));
8779 return commonCastTransforms(FI);
8782 Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) {
8783 Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
8785 return commonCastTransforms(FI);
8787 // fptosi(sitofp(X)) --> X
8788 // fptosi(uitofp(X)) --> X
8789 // This is safe if the intermediate type has enough bits in its mantissa to
8790 // accurately represent all values of X. For example, do not do this with
8791 // i64->float->i64. This is also safe for sitofp case, because any negative
8792 // 'X' value would cause an undefined result for the fptoui.
8793 if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
8794 OpI->getOperand(0)->getType() == FI.getType() &&
8795 (int)FI.getType()->getScalarSizeInBits() <=
8796 OpI->getType()->getFPMantissaWidth())
8797 return ReplaceInstUsesWith(FI, OpI->getOperand(0));
8799 return commonCastTransforms(FI);
8802 Instruction *InstCombiner::visitUIToFP(CastInst &CI) {
8803 return commonCastTransforms(CI);
8806 Instruction *InstCombiner::visitSIToFP(CastInst &CI) {
8807 return commonCastTransforms(CI);
8810 Instruction *InstCombiner::visitPtrToInt(PtrToIntInst &CI) {
8811 // If the destination integer type is smaller than the intptr_t type for
8812 // this target, do a ptrtoint to intptr_t then do a trunc. This allows the
8813 // trunc to be exposed to other transforms. Don't do this for extending
8814 // ptrtoint's, because we don't know if the target sign or zero extends its
8817 CI.getType()->getScalarSizeInBits() < TD->getPointerSizeInBits()) {
8818 Value *P = Builder->CreatePtrToInt(CI.getOperand(0),
8819 TD->getIntPtrType(CI.getContext()),
8821 return new TruncInst(P, CI.getType());
8824 return commonPointerCastTransforms(CI);
8827 Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) {
8828 // If the source integer type is larger than the intptr_t type for
8829 // this target, do a trunc to the intptr_t type, then inttoptr of it. This
8830 // allows the trunc to be exposed to other transforms. Don't do this for
8831 // extending inttoptr's, because we don't know if the target sign or zero
8832 // extends to pointers.
8833 if (TD && CI.getOperand(0)->getType()->getScalarSizeInBits() >
8834 TD->getPointerSizeInBits()) {
8835 Value *P = Builder->CreateTrunc(CI.getOperand(0),
8836 TD->getIntPtrType(CI.getContext()), "tmp");
8837 return new IntToPtrInst(P, CI.getType());
8840 if (Instruction *I = commonCastTransforms(CI))
8846 Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
8847 // If the operands are integer typed then apply the integer transforms,
8848 // otherwise just apply the common ones.
8849 Value *Src = CI.getOperand(0);
8850 const Type *SrcTy = Src->getType();
8851 const Type *DestTy = CI.getType();
8853 if (isa<PointerType>(SrcTy)) {
8854 if (Instruction *I = commonPointerCastTransforms(CI))
8857 if (Instruction *Result = commonCastTransforms(CI))
8862 // Get rid of casts from one type to the same type. These are useless and can
8863 // be replaced by the operand.
8864 if (DestTy == Src->getType())
8865 return ReplaceInstUsesWith(CI, Src);
8867 if (const PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
8868 const PointerType *SrcPTy = cast<PointerType>(SrcTy);
8869 const Type *DstElTy = DstPTy->getElementType();
8870 const Type *SrcElTy = SrcPTy->getElementType();
8872 // If the address spaces don't match, don't eliminate the bitcast, which is
8873 // required for changing types.
8874 if (SrcPTy->getAddressSpace() != DstPTy->getAddressSpace())
8877 // If we are casting a alloca to a pointer to a type of the same
8878 // size, rewrite the allocation instruction to allocate the "right" type.
8879 // There is no need to modify malloc calls because it is their bitcast that
8880 // needs to be cleaned up.
8881 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
8882 if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
8885 // If the source and destination are pointers, and this cast is equivalent
8886 // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
8887 // This can enhance SROA and other transforms that want type-safe pointers.
8888 Constant *ZeroUInt = Constant::getNullValue(Type::getInt32Ty(*Context));
8889 unsigned NumZeros = 0;
8890 while (SrcElTy != DstElTy &&
8891 isa<CompositeType>(SrcElTy) && !isa<PointerType>(SrcElTy) &&
8892 SrcElTy->getNumContainedTypes() /* not "{}" */) {
8893 SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
8897 // If we found a path from the src to dest, create the getelementptr now.
8898 if (SrcElTy == DstElTy) {
8899 SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
8900 return GetElementPtrInst::CreateInBounds(Src, Idxs.begin(), Idxs.end(), "",
8901 ((Instruction*) NULL));
8905 if (const VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
8906 if (DestVTy->getNumElements() == 1) {
8907 if (!isa<VectorType>(SrcTy)) {
8908 Value *Elem = Builder->CreateBitCast(Src, DestVTy->getElementType());
8909 return InsertElementInst::Create(UndefValue::get(DestTy), Elem,
8910 Constant::getNullValue(Type::getInt32Ty(*Context)));
8912 // FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast)
8916 if (const VectorType *SrcVTy = dyn_cast<VectorType>(SrcTy)) {
8917 if (SrcVTy->getNumElements() == 1) {
8918 if (!isa<VectorType>(DestTy)) {
8920 Builder->CreateExtractElement(Src,
8921 Constant::getNullValue(Type::getInt32Ty(*Context)));
8922 return CastInst::Create(Instruction::BitCast, Elem, DestTy);
8927 if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
8928 if (SVI->hasOneUse()) {
8929 // Okay, we have (bitconvert (shuffle ..)). Check to see if this is
8930 // a bitconvert to a vector with the same # elts.
8931 if (isa<VectorType>(DestTy) &&
8932 cast<VectorType>(DestTy)->getNumElements() ==
8933 SVI->getType()->getNumElements() &&
8934 SVI->getType()->getNumElements() ==
8935 cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements()) {
8937 // If either of the operands is a cast from CI.getType(), then
8938 // evaluating the shuffle in the casted destination's type will allow
8939 // us to eliminate at least one cast.
8940 if (((Tmp = dyn_cast<CastInst>(SVI->getOperand(0))) &&
8941 Tmp->getOperand(0)->getType() == DestTy) ||
8942 ((Tmp = dyn_cast<CastInst>(SVI->getOperand(1))) &&
8943 Tmp->getOperand(0)->getType() == DestTy)) {
8944 Value *LHS = Builder->CreateBitCast(SVI->getOperand(0), DestTy);
8945 Value *RHS = Builder->CreateBitCast(SVI->getOperand(1), DestTy);
8946 // Return a new shuffle vector. Use the same element ID's, as we
8947 // know the vector types match #elts.
8948 return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
8956 /// GetSelectFoldableOperands - We want to turn code that looks like this:
8958 /// %D = select %cond, %C, %A
8960 /// %C = select %cond, %B, 0
8963 /// Assuming that the specified instruction is an operand to the select, return
8964 /// a bitmask indicating which operands of this instruction are foldable if they
8965 /// equal the other incoming value of the select.
8967 static unsigned GetSelectFoldableOperands(Instruction *I) {
8968 switch (I->getOpcode()) {
8969 case Instruction::Add:
8970 case Instruction::Mul:
8971 case Instruction::And:
8972 case Instruction::Or:
8973 case Instruction::Xor:
8974 return 3; // Can fold through either operand.
8975 case Instruction::Sub: // Can only fold on the amount subtracted.
8976 case Instruction::Shl: // Can only fold on the shift amount.
8977 case Instruction::LShr:
8978 case Instruction::AShr:
8981 return 0; // Cannot fold
8985 /// GetSelectFoldableConstant - For the same transformation as the previous
8986 /// function, return the identity constant that goes into the select.
8987 static Constant *GetSelectFoldableConstant(Instruction *I,
8988 LLVMContext *Context) {
8989 switch (I->getOpcode()) {
8990 default: llvm_unreachable("This cannot happen!");
8991 case Instruction::Add:
8992 case Instruction::Sub:
8993 case Instruction::Or:
8994 case Instruction::Xor:
8995 case Instruction::Shl:
8996 case Instruction::LShr:
8997 case Instruction::AShr:
8998 return Constant::getNullValue(I->getType());
8999 case Instruction::And:
9000 return Constant::getAllOnesValue(I->getType());
9001 case Instruction::Mul:
9002 return ConstantInt::get(I->getType(), 1);
9006 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
9007 /// have the same opcode and only one use each. Try to simplify this.
9008 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
9010 if (TI->getNumOperands() == 1) {
9011 // If this is a non-volatile load or a cast from the same type,
9014 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
9017 return 0; // unknown unary op.
9020 // Fold this by inserting a select from the input values.
9021 SelectInst *NewSI = SelectInst::Create(SI.getCondition(), TI->getOperand(0),
9022 FI->getOperand(0), SI.getName()+".v");
9023 InsertNewInstBefore(NewSI, SI);
9024 return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
9028 // Only handle binary operators here.
9029 if (!isa<BinaryOperator>(TI))
9032 // Figure out if the operations have any operands in common.
9033 Value *MatchOp, *OtherOpT, *OtherOpF;
9035 if (TI->getOperand(0) == FI->getOperand(0)) {
9036 MatchOp = TI->getOperand(0);
9037 OtherOpT = TI->getOperand(1);
9038 OtherOpF = FI->getOperand(1);
9039 MatchIsOpZero = true;
9040 } else if (TI->getOperand(1) == FI->getOperand(1)) {
9041 MatchOp = TI->getOperand(1);
9042 OtherOpT = TI->getOperand(0);
9043 OtherOpF = FI->getOperand(0);
9044 MatchIsOpZero = false;
9045 } else if (!TI->isCommutative()) {
9047 } else if (TI->getOperand(0) == FI->getOperand(1)) {
9048 MatchOp = TI->getOperand(0);
9049 OtherOpT = TI->getOperand(1);
9050 OtherOpF = FI->getOperand(0);
9051 MatchIsOpZero = true;
9052 } else if (TI->getOperand(1) == FI->getOperand(0)) {
9053 MatchOp = TI->getOperand(1);
9054 OtherOpT = TI->getOperand(0);
9055 OtherOpF = FI->getOperand(1);
9056 MatchIsOpZero = true;
9061 // If we reach here, they do have operations in common.
9062 SelectInst *NewSI = SelectInst::Create(SI.getCondition(), OtherOpT,
9063 OtherOpF, SI.getName()+".v");
9064 InsertNewInstBefore(NewSI, SI);
9066 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
9068 return BinaryOperator::Create(BO->getOpcode(), MatchOp, NewSI);
9070 return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp);
9072 llvm_unreachable("Shouldn't get here");
9076 static bool isSelect01(Constant *C1, Constant *C2) {
9077 ConstantInt *C1I = dyn_cast<ConstantInt>(C1);
9080 ConstantInt *C2I = dyn_cast<ConstantInt>(C2);
9083 return (C1I->isZero() || C1I->isOne()) && (C2I->isZero() || C2I->isOne());
9086 /// FoldSelectIntoOp - Try fold the select into one of the operands to
9087 /// facilitate further optimization.
9088 Instruction *InstCombiner::FoldSelectIntoOp(SelectInst &SI, Value *TrueVal,
9090 // See the comment above GetSelectFoldableOperands for a description of the
9091 // transformation we are doing here.
9092 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal)) {
9093 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
9094 !isa<Constant>(FalseVal)) {
9095 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
9096 unsigned OpToFold = 0;
9097 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
9099 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
9104 Constant *C = GetSelectFoldableConstant(TVI, Context);
9105 Value *OOp = TVI->getOperand(2-OpToFold);
9106 // Avoid creating select between 2 constants unless it's selecting
9108 if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
9109 Instruction *NewSel = SelectInst::Create(SI.getCondition(), OOp, C);
9110 InsertNewInstBefore(NewSel, SI);
9111 NewSel->takeName(TVI);
9112 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
9113 return BinaryOperator::Create(BO->getOpcode(), FalseVal, NewSel);
9114 llvm_unreachable("Unknown instruction!!");
9121 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal)) {
9122 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
9123 !isa<Constant>(TrueVal)) {
9124 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
9125 unsigned OpToFold = 0;
9126 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
9128 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
9133 Constant *C = GetSelectFoldableConstant(FVI, Context);
9134 Value *OOp = FVI->getOperand(2-OpToFold);
9135 // Avoid creating select between 2 constants unless it's selecting
9137 if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
9138 Instruction *NewSel = SelectInst::Create(SI.getCondition(), C, OOp);
9139 InsertNewInstBefore(NewSel, SI);
9140 NewSel->takeName(FVI);
9141 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
9142 return BinaryOperator::Create(BO->getOpcode(), TrueVal, NewSel);
9143 llvm_unreachable("Unknown instruction!!");
9153 /// visitSelectInstWithICmp - Visit a SelectInst that has an
9154 /// ICmpInst as its first operand.
9156 Instruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI,
9158 bool Changed = false;
9159 ICmpInst::Predicate Pred = ICI->getPredicate();
9160 Value *CmpLHS = ICI->getOperand(0);
9161 Value *CmpRHS = ICI->getOperand(1);
9162 Value *TrueVal = SI.getTrueValue();
9163 Value *FalseVal = SI.getFalseValue();
9165 // Check cases where the comparison is with a constant that
9166 // can be adjusted to fit the min/max idiom. We may edit ICI in
9167 // place here, so make sure the select is the only user.
9168 if (ICI->hasOneUse())
9169 if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) {
9172 case ICmpInst::ICMP_ULT:
9173 case ICmpInst::ICMP_SLT: {
9174 // X < MIN ? T : F --> F
9175 if (CI->isMinValue(Pred == ICmpInst::ICMP_SLT))
9176 return ReplaceInstUsesWith(SI, FalseVal);
9177 // X < C ? X : C-1 --> X > C-1 ? C-1 : X
9178 Constant *AdjustedRHS = SubOne(CI);
9179 if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
9180 (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
9181 Pred = ICmpInst::getSwappedPredicate(Pred);
9182 CmpRHS = AdjustedRHS;
9183 std::swap(FalseVal, TrueVal);
9184 ICI->setPredicate(Pred);
9185 ICI->setOperand(1, CmpRHS);
9186 SI.setOperand(1, TrueVal);
9187 SI.setOperand(2, FalseVal);
9192 case ICmpInst::ICMP_UGT:
9193 case ICmpInst::ICMP_SGT: {
9194 // X > MAX ? T : F --> F
9195 if (CI->isMaxValue(Pred == ICmpInst::ICMP_SGT))
9196 return ReplaceInstUsesWith(SI, FalseVal);
9197 // X > C ? X : C+1 --> X < C+1 ? C+1 : X
9198 Constant *AdjustedRHS = AddOne(CI);
9199 if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
9200 (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
9201 Pred = ICmpInst::getSwappedPredicate(Pred);
9202 CmpRHS = AdjustedRHS;
9203 std::swap(FalseVal, TrueVal);
9204 ICI->setPredicate(Pred);
9205 ICI->setOperand(1, CmpRHS);
9206 SI.setOperand(1, TrueVal);
9207 SI.setOperand(2, FalseVal);
9214 // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if signed
9215 // (x >s -1) ? -1 : 0 -> ashr x, 31 -> all ones if not signed
9216 CmpInst::Predicate Pred = CmpInst::BAD_ICMP_PREDICATE;
9217 if (match(TrueVal, m_ConstantInt<-1>()) &&
9218 match(FalseVal, m_ConstantInt<0>()))
9219 Pred = ICI->getPredicate();
9220 else if (match(TrueVal, m_ConstantInt<0>()) &&
9221 match(FalseVal, m_ConstantInt<-1>()))
9222 Pred = CmpInst::getInversePredicate(ICI->getPredicate());
9224 if (Pred != CmpInst::BAD_ICMP_PREDICATE) {
9225 // If we are just checking for a icmp eq of a single bit and zext'ing it
9226 // to an integer, then shift the bit to the appropriate place and then
9227 // cast to integer to avoid the comparison.
9228 const APInt &Op1CV = CI->getValue();
9230 // sext (x <s 0) to i32 --> x>>s31 true if signbit set.
9231 // sext (x >s -1) to i32 --> (x>>s31)^-1 true if signbit clear.
9232 if ((Pred == ICmpInst::ICMP_SLT && Op1CV == 0) ||
9233 (Pred == ICmpInst::ICMP_SGT && Op1CV.isAllOnesValue())) {
9234 Value *In = ICI->getOperand(0);
9235 Value *Sh = ConstantInt::get(In->getType(),
9236 In->getType()->getScalarSizeInBits()-1);
9237 In = InsertNewInstBefore(BinaryOperator::CreateAShr(In, Sh,
9238 In->getName()+".lobit"),
9240 if (In->getType() != SI.getType())
9241 In = CastInst::CreateIntegerCast(In, SI.getType(),
9242 true/*SExt*/, "tmp", ICI);
9244 if (Pred == ICmpInst::ICMP_SGT)
9245 In = InsertNewInstBefore(BinaryOperator::CreateNot(In,
9246 In->getName()+".not"), *ICI);
9248 return ReplaceInstUsesWith(SI, In);
9253 if (CmpLHS == TrueVal && CmpRHS == FalseVal) {
9254 // Transform (X == Y) ? X : Y -> Y
9255 if (Pred == ICmpInst::ICMP_EQ)
9256 return ReplaceInstUsesWith(SI, FalseVal);
9257 // Transform (X != Y) ? X : Y -> X
9258 if (Pred == ICmpInst::ICMP_NE)
9259 return ReplaceInstUsesWith(SI, TrueVal);
9260 /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
9262 } else if (CmpLHS == FalseVal && CmpRHS == TrueVal) {
9263 // Transform (X == Y) ? Y : X -> X
9264 if (Pred == ICmpInst::ICMP_EQ)
9265 return ReplaceInstUsesWith(SI, FalseVal);
9266 // Transform (X != Y) ? Y : X -> Y
9267 if (Pred == ICmpInst::ICMP_NE)
9268 return ReplaceInstUsesWith(SI, TrueVal);
9269 /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
9272 /// NOTE: if we wanted to, this is where to detect integer ABS
9274 return Changed ? &SI : 0;
9278 /// CanSelectOperandBeMappingIntoPredBlock - SI is a select whose condition is a
9279 /// PHI node (but the two may be in different blocks). See if the true/false
9280 /// values (V) are live in all of the predecessor blocks of the PHI. For
9281 /// example, cases like this cannot be mapped:
9283 /// X = phi [ C1, BB1], [C2, BB2]
9285 /// Z = select X, Y, 0
9287 /// because Y is not live in BB1/BB2.
9289 static bool CanSelectOperandBeMappingIntoPredBlock(const Value *V,
9290 const SelectInst &SI) {
9291 // If the value is a non-instruction value like a constant or argument, it
9292 // can always be mapped.
9293 const Instruction *I = dyn_cast<Instruction>(V);
9294 if (I == 0) return true;
9296 // If V is a PHI node defined in the same block as the condition PHI, we can
9297 // map the arguments.
9298 const PHINode *CondPHI = cast<PHINode>(SI.getCondition());
9300 if (const PHINode *VP = dyn_cast<PHINode>(I))
9301 if (VP->getParent() == CondPHI->getParent())
9304 // Otherwise, if the PHI and select are defined in the same block and if V is
9305 // defined in a different block, then we can transform it.
9306 if (SI.getParent() == CondPHI->getParent() &&
9307 I->getParent() != CondPHI->getParent())
9310 // Otherwise we have a 'hard' case and we can't tell without doing more
9311 // detailed dominator based analysis, punt.
9315 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
9316 Value *CondVal = SI.getCondition();
9317 Value *TrueVal = SI.getTrueValue();
9318 Value *FalseVal = SI.getFalseValue();
9320 // select true, X, Y -> X
9321 // select false, X, Y -> Y
9322 if (ConstantInt *C = dyn_cast<ConstantInt>(CondVal))
9323 return ReplaceInstUsesWith(SI, C->getZExtValue() ? TrueVal : FalseVal);
9325 // select C, X, X -> X
9326 if (TrueVal == FalseVal)
9327 return ReplaceInstUsesWith(SI, TrueVal);
9329 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
9330 return ReplaceInstUsesWith(SI, FalseVal);
9331 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
9332 return ReplaceInstUsesWith(SI, TrueVal);
9333 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
9334 if (isa<Constant>(TrueVal))
9335 return ReplaceInstUsesWith(SI, TrueVal);
9337 return ReplaceInstUsesWith(SI, FalseVal);
9340 if (SI.getType() == Type::getInt1Ty(*Context)) {
9341 if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) {
9342 if (C->getZExtValue()) {
9343 // Change: A = select B, true, C --> A = or B, C
9344 return BinaryOperator::CreateOr(CondVal, FalseVal);
9346 // Change: A = select B, false, C --> A = and !B, C
9348 InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
9349 "not."+CondVal->getName()), SI);
9350 return BinaryOperator::CreateAnd(NotCond, FalseVal);
9352 } else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) {
9353 if (C->getZExtValue() == false) {
9354 // Change: A = select B, C, false --> A = and B, C
9355 return BinaryOperator::CreateAnd(CondVal, TrueVal);
9357 // Change: A = select B, C, true --> A = or !B, C
9359 InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
9360 "not."+CondVal->getName()), SI);
9361 return BinaryOperator::CreateOr(NotCond, TrueVal);
9365 // select a, b, a -> a&b
9366 // select a, a, b -> a|b
9367 if (CondVal == TrueVal)
9368 return BinaryOperator::CreateOr(CondVal, FalseVal);
9369 else if (CondVal == FalseVal)
9370 return BinaryOperator::CreateAnd(CondVal, TrueVal);
9373 // Selecting between two integer constants?
9374 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
9375 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
9376 // select C, 1, 0 -> zext C to int
9377 if (FalseValC->isZero() && TrueValC->getValue() == 1) {
9378 return CastInst::Create(Instruction::ZExt, CondVal, SI.getType());
9379 } else if (TrueValC->isZero() && FalseValC->getValue() == 1) {
9380 // select C, 0, 1 -> zext !C to int
9382 InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
9383 "not."+CondVal->getName()), SI);
9384 return CastInst::Create(Instruction::ZExt, NotCond, SI.getType());
9387 if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) {
9388 // If one of the constants is zero (we know they can't both be) and we
9389 // have an icmp instruction with zero, and we have an 'and' with the
9390 // non-constant value, eliminate this whole mess. This corresponds to
9391 // cases like this: ((X & 27) ? 27 : 0)
9392 if (TrueValC->isZero() || FalseValC->isZero())
9393 if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) &&
9394 cast<Constant>(IC->getOperand(1))->isNullValue())
9395 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
9396 if (ICA->getOpcode() == Instruction::And &&
9397 isa<ConstantInt>(ICA->getOperand(1)) &&
9398 (ICA->getOperand(1) == TrueValC ||
9399 ICA->getOperand(1) == FalseValC) &&
9400 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
9401 // Okay, now we know that everything is set up, we just don't
9402 // know whether we have a icmp_ne or icmp_eq and whether the
9403 // true or false val is the zero.
9404 bool ShouldNotVal = !TrueValC->isZero();
9405 ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
9408 V = InsertNewInstBefore(BinaryOperator::Create(
9409 Instruction::Xor, V, ICA->getOperand(1)), SI);
9410 return ReplaceInstUsesWith(SI, V);
9415 // See if we are selecting two values based on a comparison of the two values.
9416 if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
9417 if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
9418 // Transform (X == Y) ? X : Y -> Y
9419 if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
9420 // This is not safe in general for floating point:
9421 // consider X== -0, Y== +0.
9422 // It becomes safe if either operand is a nonzero constant.
9423 ConstantFP *CFPt, *CFPf;
9424 if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
9425 !CFPt->getValueAPF().isZero()) ||
9426 ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
9427 !CFPf->getValueAPF().isZero()))
9428 return ReplaceInstUsesWith(SI, FalseVal);
9430 // Transform (X != Y) ? X : Y -> X
9431 if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
9432 return ReplaceInstUsesWith(SI, TrueVal);
9433 // NOTE: if we wanted to, this is where to detect MIN/MAX
9435 } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
9436 // Transform (X == Y) ? Y : X -> X
9437 if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
9438 // This is not safe in general for floating point:
9439 // consider X== -0, Y== +0.
9440 // It becomes safe if either operand is a nonzero constant.
9441 ConstantFP *CFPt, *CFPf;
9442 if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
9443 !CFPt->getValueAPF().isZero()) ||
9444 ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
9445 !CFPf->getValueAPF().isZero()))
9446 return ReplaceInstUsesWith(SI, FalseVal);
9448 // Transform (X != Y) ? Y : X -> Y
9449 if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
9450 return ReplaceInstUsesWith(SI, TrueVal);
9451 // NOTE: if we wanted to, this is where to detect MIN/MAX
9453 // NOTE: if we wanted to, this is where to detect ABS
9456 // See if we are selecting two values based on a comparison of the two values.
9457 if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal))
9458 if (Instruction *Result = visitSelectInstWithICmp(SI, ICI))
9461 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
9462 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
9463 if (TI->hasOneUse() && FI->hasOneUse()) {
9464 Instruction *AddOp = 0, *SubOp = 0;
9466 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
9467 if (TI->getOpcode() == FI->getOpcode())
9468 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
9471 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
9472 // even legal for FP.
9473 if ((TI->getOpcode() == Instruction::Sub &&
9474 FI->getOpcode() == Instruction::Add) ||
9475 (TI->getOpcode() == Instruction::FSub &&
9476 FI->getOpcode() == Instruction::FAdd)) {
9477 AddOp = FI; SubOp = TI;
9478 } else if ((FI->getOpcode() == Instruction::Sub &&
9479 TI->getOpcode() == Instruction::Add) ||
9480 (FI->getOpcode() == Instruction::FSub &&
9481 TI->getOpcode() == Instruction::FAdd)) {
9482 AddOp = TI; SubOp = FI;
9486 Value *OtherAddOp = 0;
9487 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
9488 OtherAddOp = AddOp->getOperand(1);
9489 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
9490 OtherAddOp = AddOp->getOperand(0);
9494 // So at this point we know we have (Y -> OtherAddOp):
9495 // select C, (add X, Y), (sub X, Z)
9496 Value *NegVal; // Compute -Z
9497 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
9498 NegVal = ConstantExpr::getNeg(C);
9500 NegVal = InsertNewInstBefore(
9501 BinaryOperator::CreateNeg(SubOp->getOperand(1),
9505 Value *NewTrueOp = OtherAddOp;
9506 Value *NewFalseOp = NegVal;
9508 std::swap(NewTrueOp, NewFalseOp);
9509 Instruction *NewSel =
9510 SelectInst::Create(CondVal, NewTrueOp,
9511 NewFalseOp, SI.getName() + ".p");
9513 NewSel = InsertNewInstBefore(NewSel, SI);
9514 return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
9519 // See if we can fold the select into one of our operands.
9520 if (SI.getType()->isInteger()) {
9521 Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal);
9526 // See if we can fold the select into a phi node if the condition is a select.
9527 if (isa<PHINode>(SI.getCondition()))
9528 // The true/false values have to be live in the PHI predecessor's blocks.
9529 if (CanSelectOperandBeMappingIntoPredBlock(TrueVal, SI) &&
9530 CanSelectOperandBeMappingIntoPredBlock(FalseVal, SI))
9531 if (Instruction *NV = FoldOpIntoPhi(SI))
9534 if (BinaryOperator::isNot(CondVal)) {
9535 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
9536 SI.setOperand(1, FalseVal);
9537 SI.setOperand(2, TrueVal);
9544 /// EnforceKnownAlignment - If the specified pointer points to an object that
9545 /// we control, modify the object's alignment to PrefAlign. This isn't
9546 /// often possible though. If alignment is important, a more reliable approach
9547 /// is to simply align all global variables and allocation instructions to
9548 /// their preferred alignment from the beginning.
9550 static unsigned EnforceKnownAlignment(Value *V,
9551 unsigned Align, unsigned PrefAlign) {
9553 User *U = dyn_cast<User>(V);
9554 if (!U) return Align;
9556 switch (Operator::getOpcode(U)) {
9558 case Instruction::BitCast:
9559 return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
9560 case Instruction::GetElementPtr: {
9561 // If all indexes are zero, it is just the alignment of the base pointer.
9562 bool AllZeroOperands = true;
9563 for (User::op_iterator i = U->op_begin() + 1, e = U->op_end(); i != e; ++i)
9564 if (!isa<Constant>(*i) ||
9565 !cast<Constant>(*i)->isNullValue()) {
9566 AllZeroOperands = false;
9570 if (AllZeroOperands) {
9571 // Treat this like a bitcast.
9572 return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
9578 if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
9579 // If there is a large requested alignment and we can, bump up the alignment
9581 if (!GV->isDeclaration()) {
9582 if (GV->getAlignment() >= PrefAlign)
9583 Align = GV->getAlignment();
9585 GV->setAlignment(PrefAlign);
9589 } else if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
9590 // If there is a requested alignment and if this is an alloca, round up.
9591 if (AI->getAlignment() >= PrefAlign)
9592 Align = AI->getAlignment();
9594 AI->setAlignment(PrefAlign);
9602 /// GetOrEnforceKnownAlignment - If the specified pointer has an alignment that
9603 /// we can determine, return it, otherwise return 0. If PrefAlign is specified,
9604 /// and it is more than the alignment of the ultimate object, see if we can
9605 /// increase the alignment of the ultimate object, making this check succeed.
9606 unsigned InstCombiner::GetOrEnforceKnownAlignment(Value *V,
9607 unsigned PrefAlign) {
9608 unsigned BitWidth = TD ? TD->getTypeSizeInBits(V->getType()) :
9609 sizeof(PrefAlign) * CHAR_BIT;
9610 APInt Mask = APInt::getAllOnesValue(BitWidth);
9611 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
9612 ComputeMaskedBits(V, Mask, KnownZero, KnownOne);
9613 unsigned TrailZ = KnownZero.countTrailingOnes();
9614 unsigned Align = 1u << std::min(BitWidth - 1, TrailZ);
9616 if (PrefAlign > Align)
9617 Align = EnforceKnownAlignment(V, Align, PrefAlign);
9619 // We don't need to make any adjustment.
9623 Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
9624 unsigned DstAlign = GetOrEnforceKnownAlignment(MI->getOperand(1));
9625 unsigned SrcAlign = GetOrEnforceKnownAlignment(MI->getOperand(2));
9626 unsigned MinAlign = std::min(DstAlign, SrcAlign);
9627 unsigned CopyAlign = MI->getAlignment();
9629 if (CopyAlign < MinAlign) {
9630 MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
9635 // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
9637 ConstantInt *MemOpLength = dyn_cast<ConstantInt>(MI->getOperand(3));
9638 if (MemOpLength == 0) return 0;
9640 // Source and destination pointer types are always "i8*" for intrinsic. See
9641 // if the size is something we can handle with a single primitive load/store.
9642 // A single load+store correctly handles overlapping memory in the memmove
9644 unsigned Size = MemOpLength->getZExtValue();
9645 if (Size == 0) return MI; // Delete this mem transfer.
9647 if (Size > 8 || (Size&(Size-1)))
9648 return 0; // If not 1/2/4/8 bytes, exit.
9650 // Use an integer load+store unless we can find something better.
9652 PointerType::getUnqual(IntegerType::get(*Context, Size<<3));
9654 // Memcpy forces the use of i8* for the source and destination. That means
9655 // that if you're using memcpy to move one double around, you'll get a cast
9656 // from double* to i8*. We'd much rather use a double load+store rather than
9657 // an i64 load+store, here because this improves the odds that the source or
9658 // dest address will be promotable. See if we can find a better type than the
9659 // integer datatype.
9660 if (Value *Op = getBitCastOperand(MI->getOperand(1))) {
9661 const Type *SrcETy = cast<PointerType>(Op->getType())->getElementType();
9662 if (TD && SrcETy->isSized() && TD->getTypeStoreSize(SrcETy) == Size) {
9663 // The SrcETy might be something like {{{double}}} or [1 x double]. Rip
9664 // down through these levels if so.
9665 while (!SrcETy->isSingleValueType()) {
9666 if (const StructType *STy = dyn_cast<StructType>(SrcETy)) {
9667 if (STy->getNumElements() == 1)
9668 SrcETy = STy->getElementType(0);
9671 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(SrcETy)) {
9672 if (ATy->getNumElements() == 1)
9673 SrcETy = ATy->getElementType();
9680 if (SrcETy->isSingleValueType())
9681 NewPtrTy = PointerType::getUnqual(SrcETy);
9686 // If the memcpy/memmove provides better alignment info than we can
9688 SrcAlign = std::max(SrcAlign, CopyAlign);
9689 DstAlign = std::max(DstAlign, CopyAlign);
9691 Value *Src = Builder->CreateBitCast(MI->getOperand(2), NewPtrTy);
9692 Value *Dest = Builder->CreateBitCast(MI->getOperand(1), NewPtrTy);
9693 Instruction *L = new LoadInst(Src, "tmp", false, SrcAlign);
9694 InsertNewInstBefore(L, *MI);
9695 InsertNewInstBefore(new StoreInst(L, Dest, false, DstAlign), *MI);
9697 // Set the size of the copy to 0, it will be deleted on the next iteration.
9698 MI->setOperand(3, Constant::getNullValue(MemOpLength->getType()));
9702 Instruction *InstCombiner::SimplifyMemSet(MemSetInst *MI) {
9703 unsigned Alignment = GetOrEnforceKnownAlignment(MI->getDest());
9704 if (MI->getAlignment() < Alignment) {
9705 MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
9710 // Extract the length and alignment and fill if they are constant.
9711 ConstantInt *LenC = dyn_cast<ConstantInt>(MI->getLength());
9712 ConstantInt *FillC = dyn_cast<ConstantInt>(MI->getValue());
9713 if (!LenC || !FillC || FillC->getType() != Type::getInt8Ty(*Context))
9715 uint64_t Len = LenC->getZExtValue();
9716 Alignment = MI->getAlignment();
9718 // If the length is zero, this is a no-op
9719 if (Len == 0) return MI; // memset(d,c,0,a) -> noop
9721 // memset(s,c,n) -> store s, c (for n=1,2,4,8)
9722 if (Len <= 8 && isPowerOf2_32((uint32_t)Len)) {
9723 const Type *ITy = IntegerType::get(*Context, Len*8); // n=1 -> i8.
9725 Value *Dest = MI->getDest();
9726 Dest = Builder->CreateBitCast(Dest, PointerType::getUnqual(ITy));
9728 // Alignment 0 is identity for alignment 1 for memset, but not store.
9729 if (Alignment == 0) Alignment = 1;
9731 // Extract the fill value and store.
9732 uint64_t Fill = FillC->getZExtValue()*0x0101010101010101ULL;
9733 InsertNewInstBefore(new StoreInst(ConstantInt::get(ITy, Fill),
9734 Dest, false, Alignment), *MI);
9736 // Set the size of the copy to 0, it will be deleted on the next iteration.
9737 MI->setLength(Constant::getNullValue(LenC->getType()));
9745 /// visitCallInst - CallInst simplification. This mostly only handles folding
9746 /// of intrinsic instructions. For normal calls, it allows visitCallSite to do
9747 /// the heavy lifting.
9749 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
9750 // If the caller function is nounwind, mark the call as nounwind, even if the
9752 if (CI.getParent()->getParent()->doesNotThrow() &&
9753 !CI.doesNotThrow()) {
9754 CI.setDoesNotThrow();
9758 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
9759 if (!II) return visitCallSite(&CI);
9761 // Intrinsics cannot occur in an invoke, so handle them here instead of in
9763 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
9764 bool Changed = false;
9766 // memmove/cpy/set of zero bytes is a noop.
9767 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
9768 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
9770 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
9771 if (CI->getZExtValue() == 1) {
9772 // Replace the instruction with just byte operations. We would
9773 // transform other cases to loads/stores, but we don't know if
9774 // alignment is sufficient.
9778 // If we have a memmove and the source operation is a constant global,
9779 // then the source and dest pointers can't alias, so we can change this
9780 // into a call to memcpy.
9781 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI)) {
9782 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
9783 if (GVSrc->isConstant()) {
9784 Module *M = CI.getParent()->getParent()->getParent();
9785 Intrinsic::ID MemCpyID = Intrinsic::memcpy;
9787 Tys[0] = CI.getOperand(3)->getType();
9789 Intrinsic::getDeclaration(M, MemCpyID, Tys, 1));
9793 // memmove(x,x,size) -> noop.
9794 if (MMI->getSource() == MMI->getDest())
9795 return EraseInstFromFunction(CI);
9798 // If we can determine a pointer alignment that is bigger than currently
9799 // set, update the alignment.
9800 if (isa<MemTransferInst>(MI)) {
9801 if (Instruction *I = SimplifyMemTransfer(MI))
9803 } else if (MemSetInst *MSI = dyn_cast<MemSetInst>(MI)) {
9804 if (Instruction *I = SimplifyMemSet(MSI))
9808 if (Changed) return II;
9811 switch (II->getIntrinsicID()) {
9813 case Intrinsic::bswap:
9814 // bswap(bswap(x)) -> x
9815 if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(II->getOperand(1)))
9816 if (Operand->getIntrinsicID() == Intrinsic::bswap)
9817 return ReplaceInstUsesWith(CI, Operand->getOperand(1));
9819 case Intrinsic::ppc_altivec_lvx:
9820 case Intrinsic::ppc_altivec_lvxl:
9821 case Intrinsic::x86_sse_loadu_ps:
9822 case Intrinsic::x86_sse2_loadu_pd:
9823 case Intrinsic::x86_sse2_loadu_dq:
9824 // Turn PPC lvx -> load if the pointer is known aligned.
9825 // Turn X86 loadups -> load if the pointer is known aligned.
9826 if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
9827 Value *Ptr = Builder->CreateBitCast(II->getOperand(1),
9828 PointerType::getUnqual(II->getType()));
9829 return new LoadInst(Ptr);
9832 case Intrinsic::ppc_altivec_stvx:
9833 case Intrinsic::ppc_altivec_stvxl:
9834 // Turn stvx -> store if the pointer is known aligned.
9835 if (GetOrEnforceKnownAlignment(II->getOperand(2), 16) >= 16) {
9836 const Type *OpPtrTy =
9837 PointerType::getUnqual(II->getOperand(1)->getType());
9838 Value *Ptr = Builder->CreateBitCast(II->getOperand(2), OpPtrTy);
9839 return new StoreInst(II->getOperand(1), Ptr);
9842 case Intrinsic::x86_sse_storeu_ps:
9843 case Intrinsic::x86_sse2_storeu_pd:
9844 case Intrinsic::x86_sse2_storeu_dq:
9845 // Turn X86 storeu -> store if the pointer is known aligned.
9846 if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
9847 const Type *OpPtrTy =
9848 PointerType::getUnqual(II->getOperand(2)->getType());
9849 Value *Ptr = Builder->CreateBitCast(II->getOperand(1), OpPtrTy);
9850 return new StoreInst(II->getOperand(2), Ptr);
9854 case Intrinsic::x86_sse_cvttss2si: {
9855 // These intrinsics only demands the 0th element of its input vector. If
9856 // we can simplify the input based on that, do so now.
9858 cast<VectorType>(II->getOperand(1)->getType())->getNumElements();
9859 APInt DemandedElts(VWidth, 1);
9860 APInt UndefElts(VWidth, 0);
9861 if (Value *V = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts,
9863 II->setOperand(1, V);
9869 case Intrinsic::ppc_altivec_vperm:
9870 // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
9871 if (ConstantVector *Mask = dyn_cast<ConstantVector>(II->getOperand(3))) {
9872 assert(Mask->getNumOperands() == 16 && "Bad type for intrinsic!");
9874 // Check that all of the elements are integer constants or undefs.
9875 bool AllEltsOk = true;
9876 for (unsigned i = 0; i != 16; ++i) {
9877 if (!isa<ConstantInt>(Mask->getOperand(i)) &&
9878 !isa<UndefValue>(Mask->getOperand(i))) {
9885 // Cast the input vectors to byte vectors.
9886 Value *Op0 = Builder->CreateBitCast(II->getOperand(1), Mask->getType());
9887 Value *Op1 = Builder->CreateBitCast(II->getOperand(2), Mask->getType());
9888 Value *Result = UndefValue::get(Op0->getType());
9890 // Only extract each element once.
9891 Value *ExtractedElts[32];
9892 memset(ExtractedElts, 0, sizeof(ExtractedElts));
9894 for (unsigned i = 0; i != 16; ++i) {
9895 if (isa<UndefValue>(Mask->getOperand(i)))
9897 unsigned Idx=cast<ConstantInt>(Mask->getOperand(i))->getZExtValue();
9898 Idx &= 31; // Match the hardware behavior.
9900 if (ExtractedElts[Idx] == 0) {
9901 ExtractedElts[Idx] =
9902 Builder->CreateExtractElement(Idx < 16 ? Op0 : Op1,
9903 ConstantInt::get(Type::getInt32Ty(*Context), Idx&15, false),
9907 // Insert this value into the result vector.
9908 Result = Builder->CreateInsertElement(Result, ExtractedElts[Idx],
9909 ConstantInt::get(Type::getInt32Ty(*Context), i, false),
9912 return CastInst::Create(Instruction::BitCast, Result, CI.getType());
9917 case Intrinsic::stackrestore: {
9918 // If the save is right next to the restore, remove the restore. This can
9919 // happen when variable allocas are DCE'd.
9920 if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
9921 if (SS->getIntrinsicID() == Intrinsic::stacksave) {
9922 BasicBlock::iterator BI = SS;
9924 return EraseInstFromFunction(CI);
9928 // Scan down this block to see if there is another stack restore in the
9929 // same block without an intervening call/alloca.
9930 BasicBlock::iterator BI = II;
9931 TerminatorInst *TI = II->getParent()->getTerminator();
9932 bool CannotRemove = false;
9933 for (++BI; &*BI != TI; ++BI) {
9934 if (isa<AllocaInst>(BI) || isMalloc(BI)) {
9935 CannotRemove = true;
9938 if (CallInst *BCI = dyn_cast<CallInst>(BI)) {
9939 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BCI)) {
9940 // If there is a stackrestore below this one, remove this one.
9941 if (II->getIntrinsicID() == Intrinsic::stackrestore)
9942 return EraseInstFromFunction(CI);
9943 // Otherwise, ignore the intrinsic.
9945 // If we found a non-intrinsic call, we can't remove the stack
9947 CannotRemove = true;
9953 // If the stack restore is in a return/unwind block and if there are no
9954 // allocas or calls between the restore and the return, nuke the restore.
9955 if (!CannotRemove && (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)))
9956 return EraseInstFromFunction(CI);
9961 return visitCallSite(II);
9964 // InvokeInst simplification
9966 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
9967 return visitCallSite(&II);
9970 /// isSafeToEliminateVarargsCast - If this cast does not affect the value
9971 /// passed through the varargs area, we can eliminate the use of the cast.
9972 static bool isSafeToEliminateVarargsCast(const CallSite CS,
9973 const CastInst * const CI,
9974 const TargetData * const TD,
9976 if (!CI->isLosslessCast())
9979 // The size of ByVal arguments is derived from the type, so we
9980 // can't change to a type with a different size. If the size were
9981 // passed explicitly we could avoid this check.
9982 if (!CS.paramHasAttr(ix, Attribute::ByVal))
9986 cast<PointerType>(CI->getOperand(0)->getType())->getElementType();
9987 const Type* DstTy = cast<PointerType>(CI->getType())->getElementType();
9988 if (!SrcTy->isSized() || !DstTy->isSized())
9990 if (!TD || TD->getTypeAllocSize(SrcTy) != TD->getTypeAllocSize(DstTy))
9995 // visitCallSite - Improvements for call and invoke instructions.
9997 Instruction *InstCombiner::visitCallSite(CallSite CS) {
9998 bool Changed = false;
10000 // If the callee is a constexpr cast of a function, attempt to move the cast
10001 // to the arguments of the call/invoke.
10002 if (transformConstExprCastCall(CS)) return 0;
10004 Value *Callee = CS.getCalledValue();
10006 if (Function *CalleeF = dyn_cast<Function>(Callee))
10007 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
10008 Instruction *OldCall = CS.getInstruction();
10009 // If the call and callee calling conventions don't match, this call must
10010 // be unreachable, as the call is undefined.
10011 new StoreInst(ConstantInt::getTrue(*Context),
10012 UndefValue::get(Type::getInt1PtrTy(*Context)),
10014 // If OldCall dues not return void then replaceAllUsesWith undef.
10015 // This allows ValueHandlers and custom metadata to adjust itself.
10016 if (!OldCall->getType()->isVoidTy())
10017 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
10018 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
10019 return EraseInstFromFunction(*OldCall);
10023 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
10024 // This instruction is not reachable, just remove it. We insert a store to
10025 // undef so that we know that this code is not reachable, despite the fact
10026 // that we can't modify the CFG here.
10027 new StoreInst(ConstantInt::getTrue(*Context),
10028 UndefValue::get(Type::getInt1PtrTy(*Context)),
10029 CS.getInstruction());
10031 // If CS dues not return void then replaceAllUsesWith undef.
10032 // This allows ValueHandlers and custom metadata to adjust itself.
10033 if (!CS.getInstruction()->getType()->isVoidTy())
10034 CS.getInstruction()->
10035 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
10037 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
10038 // Don't break the CFG, insert a dummy cond branch.
10039 BranchInst::Create(II->getNormalDest(), II->getUnwindDest(),
10040 ConstantInt::getTrue(*Context), II);
10042 return EraseInstFromFunction(*CS.getInstruction());
10045 if (BitCastInst *BC = dyn_cast<BitCastInst>(Callee))
10046 if (IntrinsicInst *In = dyn_cast<IntrinsicInst>(BC->getOperand(0)))
10047 if (In->getIntrinsicID() == Intrinsic::init_trampoline)
10048 return transformCallThroughTrampoline(CS);
10050 const PointerType *PTy = cast<PointerType>(Callee->getType());
10051 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
10052 if (FTy->isVarArg()) {
10053 int ix = FTy->getNumParams() + (isa<InvokeInst>(Callee) ? 3 : 1);
10054 // See if we can optimize any arguments passed through the varargs area of
10056 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
10057 E = CS.arg_end(); I != E; ++I, ++ix) {
10058 CastInst *CI = dyn_cast<CastInst>(*I);
10059 if (CI && isSafeToEliminateVarargsCast(CS, CI, TD, ix)) {
10060 *I = CI->getOperand(0);
10066 if (isa<InlineAsm>(Callee) && !CS.doesNotThrow()) {
10067 // Inline asm calls cannot throw - mark them 'nounwind'.
10068 CS.setDoesNotThrow();
10072 return Changed ? CS.getInstruction() : 0;
10075 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
10076 // attempt to move the cast to the arguments of the call/invoke.
10078 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
10079 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
10080 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
10081 if (CE->getOpcode() != Instruction::BitCast ||
10082 !isa<Function>(CE->getOperand(0)))
10084 Function *Callee = cast<Function>(CE->getOperand(0));
10085 Instruction *Caller = CS.getInstruction();
10086 const AttrListPtr &CallerPAL = CS.getAttributes();
10088 // Okay, this is a cast from a function to a different type. Unless doing so
10089 // would cause a type conversion of one of our arguments, change this call to
10090 // be a direct call with arguments casted to the appropriate types.
10092 const FunctionType *FT = Callee->getFunctionType();
10093 const Type *OldRetTy = Caller->getType();
10094 const Type *NewRetTy = FT->getReturnType();
10096 if (isa<StructType>(NewRetTy))
10097 return false; // TODO: Handle multiple return values.
10099 // Check to see if we are changing the return type...
10100 if (OldRetTy != NewRetTy) {
10101 if (Callee->isDeclaration() &&
10102 // Conversion is ok if changing from one pointer type to another or from
10103 // a pointer to an integer of the same size.
10104 !((isa<PointerType>(OldRetTy) || !TD ||
10105 OldRetTy == TD->getIntPtrType(Caller->getContext())) &&
10106 (isa<PointerType>(NewRetTy) || !TD ||
10107 NewRetTy == TD->getIntPtrType(Caller->getContext()))))
10108 return false; // Cannot transform this return value.
10110 if (!Caller->use_empty() &&
10111 // void -> non-void is handled specially
10112 !NewRetTy->isVoidTy() && !CastInst::isCastable(NewRetTy, OldRetTy))
10113 return false; // Cannot transform this return value.
10115 if (!CallerPAL.isEmpty() && !Caller->use_empty()) {
10116 Attributes RAttrs = CallerPAL.getRetAttributes();
10117 if (RAttrs & Attribute::typeIncompatible(NewRetTy))
10118 return false; // Attribute not compatible with transformed value.
10121 // If the callsite is an invoke instruction, and the return value is used by
10122 // a PHI node in a successor, we cannot change the return type of the call
10123 // because there is no place to put the cast instruction (without breaking
10124 // the critical edge). Bail out in this case.
10125 if (!Caller->use_empty())
10126 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
10127 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
10129 if (PHINode *PN = dyn_cast<PHINode>(*UI))
10130 if (PN->getParent() == II->getNormalDest() ||
10131 PN->getParent() == II->getUnwindDest())
10135 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
10136 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
10138 CallSite::arg_iterator AI = CS.arg_begin();
10139 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
10140 const Type *ParamTy = FT->getParamType(i);
10141 const Type *ActTy = (*AI)->getType();
10143 if (!CastInst::isCastable(ActTy, ParamTy))
10144 return false; // Cannot transform this parameter value.
10146 if (CallerPAL.getParamAttributes(i + 1)
10147 & Attribute::typeIncompatible(ParamTy))
10148 return false; // Attribute not compatible with transformed value.
10150 // Converting from one pointer type to another or between a pointer and an
10151 // integer of the same size is safe even if we do not have a body.
10152 bool isConvertible = ActTy == ParamTy ||
10153 (TD && ((isa<PointerType>(ParamTy) ||
10154 ParamTy == TD->getIntPtrType(Caller->getContext())) &&
10155 (isa<PointerType>(ActTy) ||
10156 ActTy == TD->getIntPtrType(Caller->getContext()))));
10157 if (Callee->isDeclaration() && !isConvertible) return false;
10160 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
10161 Callee->isDeclaration())
10162 return false; // Do not delete arguments unless we have a function body.
10164 if (FT->getNumParams() < NumActualArgs && FT->isVarArg() &&
10165 !CallerPAL.isEmpty())
10166 // In this case we have more arguments than the new function type, but we
10167 // won't be dropping them. Check that these extra arguments have attributes
10168 // that are compatible with being a vararg call argument.
10169 for (unsigned i = CallerPAL.getNumSlots(); i; --i) {
10170 if (CallerPAL.getSlot(i - 1).Index <= FT->getNumParams())
10172 Attributes PAttrs = CallerPAL.getSlot(i - 1).Attrs;
10173 if (PAttrs & Attribute::VarArgsIncompatible)
10177 // Okay, we decided that this is a safe thing to do: go ahead and start
10178 // inserting cast instructions as necessary...
10179 std::vector<Value*> Args;
10180 Args.reserve(NumActualArgs);
10181 SmallVector<AttributeWithIndex, 8> attrVec;
10182 attrVec.reserve(NumCommonArgs);
10184 // Get any return attributes.
10185 Attributes RAttrs = CallerPAL.getRetAttributes();
10187 // If the return value is not being used, the type may not be compatible
10188 // with the existing attributes. Wipe out any problematic attributes.
10189 RAttrs &= ~Attribute::typeIncompatible(NewRetTy);
10191 // Add the new return attributes.
10193 attrVec.push_back(AttributeWithIndex::get(0, RAttrs));
10195 AI = CS.arg_begin();
10196 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
10197 const Type *ParamTy = FT->getParamType(i);
10198 if ((*AI)->getType() == ParamTy) {
10199 Args.push_back(*AI);
10201 Instruction::CastOps opcode = CastInst::getCastOpcode(*AI,
10202 false, ParamTy, false);
10203 Args.push_back(Builder->CreateCast(opcode, *AI, ParamTy, "tmp"));
10206 // Add any parameter attributes.
10207 if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1))
10208 attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
10211 // If the function takes more arguments than the call was taking, add them
10213 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
10214 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
10216 // If we are removing arguments to the function, emit an obnoxious warning.
10217 if (FT->getNumParams() < NumActualArgs) {
10218 if (!FT->isVarArg()) {
10219 errs() << "WARNING: While resolving call to function '"
10220 << Callee->getName() << "' arguments were dropped!\n";
10222 // Add all of the arguments in their promoted form to the arg list.
10223 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
10224 const Type *PTy = getPromotedType((*AI)->getType());
10225 if (PTy != (*AI)->getType()) {
10226 // Must promote to pass through va_arg area!
10227 Instruction::CastOps opcode =
10228 CastInst::getCastOpcode(*AI, false, PTy, false);
10229 Args.push_back(Builder->CreateCast(opcode, *AI, PTy, "tmp"));
10231 Args.push_back(*AI);
10234 // Add any parameter attributes.
10235 if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1))
10236 attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
10241 if (Attributes FnAttrs = CallerPAL.getFnAttributes())
10242 attrVec.push_back(AttributeWithIndex::get(~0, FnAttrs));
10244 if (NewRetTy->isVoidTy())
10245 Caller->setName(""); // Void type should not have a name.
10247 const AttrListPtr &NewCallerPAL = AttrListPtr::get(attrVec.begin(),
10251 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
10252 NC = InvokeInst::Create(Callee, II->getNormalDest(), II->getUnwindDest(),
10253 Args.begin(), Args.end(),
10254 Caller->getName(), Caller);
10255 cast<InvokeInst>(NC)->setCallingConv(II->getCallingConv());
10256 cast<InvokeInst>(NC)->setAttributes(NewCallerPAL);
10258 NC = CallInst::Create(Callee, Args.begin(), Args.end(),
10259 Caller->getName(), Caller);
10260 CallInst *CI = cast<CallInst>(Caller);
10261 if (CI->isTailCall())
10262 cast<CallInst>(NC)->setTailCall();
10263 cast<CallInst>(NC)->setCallingConv(CI->getCallingConv());
10264 cast<CallInst>(NC)->setAttributes(NewCallerPAL);
10267 // Insert a cast of the return type as necessary.
10269 if (OldRetTy != NV->getType() && !Caller->use_empty()) {
10270 if (!NV->getType()->isVoidTy()) {
10271 Instruction::CastOps opcode = CastInst::getCastOpcode(NC, false,
10273 NV = NC = CastInst::Create(opcode, NC, OldRetTy, "tmp");
10275 // If this is an invoke instruction, we should insert it after the first
10276 // non-phi, instruction in the normal successor block.
10277 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
10278 BasicBlock::iterator I = II->getNormalDest()->getFirstNonPHI();
10279 InsertNewInstBefore(NC, *I);
10281 // Otherwise, it's a call, just insert cast right after the call instr
10282 InsertNewInstBefore(NC, *Caller);
10284 Worklist.AddUsersToWorkList(*Caller);
10286 NV = UndefValue::get(Caller->getType());
10291 if (!Caller->use_empty())
10292 Caller->replaceAllUsesWith(NV);
10294 EraseInstFromFunction(*Caller);
10298 // transformCallThroughTrampoline - Turn a call to a function created by the
10299 // init_trampoline intrinsic into a direct call to the underlying function.
10301 Instruction *InstCombiner::transformCallThroughTrampoline(CallSite CS) {
10302 Value *Callee = CS.getCalledValue();
10303 const PointerType *PTy = cast<PointerType>(Callee->getType());
10304 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
10305 const AttrListPtr &Attrs = CS.getAttributes();
10307 // If the call already has the 'nest' attribute somewhere then give up -
10308 // otherwise 'nest' would occur twice after splicing in the chain.
10309 if (Attrs.hasAttrSomewhere(Attribute::Nest))
10312 IntrinsicInst *Tramp =
10313 cast<IntrinsicInst>(cast<BitCastInst>(Callee)->getOperand(0));
10315 Function *NestF = cast<Function>(Tramp->getOperand(2)->stripPointerCasts());
10316 const PointerType *NestFPTy = cast<PointerType>(NestF->getType());
10317 const FunctionType *NestFTy = cast<FunctionType>(NestFPTy->getElementType());
10319 const AttrListPtr &NestAttrs = NestF->getAttributes();
10320 if (!NestAttrs.isEmpty()) {
10321 unsigned NestIdx = 1;
10322 const Type *NestTy = 0;
10323 Attributes NestAttr = Attribute::None;
10325 // Look for a parameter marked with the 'nest' attribute.
10326 for (FunctionType::param_iterator I = NestFTy->param_begin(),
10327 E = NestFTy->param_end(); I != E; ++NestIdx, ++I)
10328 if (NestAttrs.paramHasAttr(NestIdx, Attribute::Nest)) {
10329 // Record the parameter type and any other attributes.
10331 NestAttr = NestAttrs.getParamAttributes(NestIdx);
10336 Instruction *Caller = CS.getInstruction();
10337 std::vector<Value*> NewArgs;
10338 NewArgs.reserve(unsigned(CS.arg_end()-CS.arg_begin())+1);
10340 SmallVector<AttributeWithIndex, 8> NewAttrs;
10341 NewAttrs.reserve(Attrs.getNumSlots() + 1);
10343 // Insert the nest argument into the call argument list, which may
10344 // mean appending it. Likewise for attributes.
10346 // Add any result attributes.
10347 if (Attributes Attr = Attrs.getRetAttributes())
10348 NewAttrs.push_back(AttributeWithIndex::get(0, Attr));
10352 CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
10354 if (Idx == NestIdx) {
10355 // Add the chain argument and attributes.
10356 Value *NestVal = Tramp->getOperand(3);
10357 if (NestVal->getType() != NestTy)
10358 NestVal = new BitCastInst(NestVal, NestTy, "nest", Caller);
10359 NewArgs.push_back(NestVal);
10360 NewAttrs.push_back(AttributeWithIndex::get(NestIdx, NestAttr));
10366 // Add the original argument and attributes.
10367 NewArgs.push_back(*I);
10368 if (Attributes Attr = Attrs.getParamAttributes(Idx))
10370 (AttributeWithIndex::get(Idx + (Idx >= NestIdx), Attr));
10376 // Add any function attributes.
10377 if (Attributes Attr = Attrs.getFnAttributes())
10378 NewAttrs.push_back(AttributeWithIndex::get(~0, Attr));
10380 // The trampoline may have been bitcast to a bogus type (FTy).
10381 // Handle this by synthesizing a new function type, equal to FTy
10382 // with the chain parameter inserted.
10384 std::vector<const Type*> NewTypes;
10385 NewTypes.reserve(FTy->getNumParams()+1);
10387 // Insert the chain's type into the list of parameter types, which may
10388 // mean appending it.
10391 FunctionType::param_iterator I = FTy->param_begin(),
10392 E = FTy->param_end();
10395 if (Idx == NestIdx)
10396 // Add the chain's type.
10397 NewTypes.push_back(NestTy);
10402 // Add the original type.
10403 NewTypes.push_back(*I);
10409 // Replace the trampoline call with a direct call. Let the generic
10410 // code sort out any function type mismatches.
10411 FunctionType *NewFTy = FunctionType::get(FTy->getReturnType(), NewTypes,
10413 Constant *NewCallee =
10414 NestF->getType() == PointerType::getUnqual(NewFTy) ?
10415 NestF : ConstantExpr::getBitCast(NestF,
10416 PointerType::getUnqual(NewFTy));
10417 const AttrListPtr &NewPAL = AttrListPtr::get(NewAttrs.begin(),
10420 Instruction *NewCaller;
10421 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
10422 NewCaller = InvokeInst::Create(NewCallee,
10423 II->getNormalDest(), II->getUnwindDest(),
10424 NewArgs.begin(), NewArgs.end(),
10425 Caller->getName(), Caller);
10426 cast<InvokeInst>(NewCaller)->setCallingConv(II->getCallingConv());
10427 cast<InvokeInst>(NewCaller)->setAttributes(NewPAL);
10429 NewCaller = CallInst::Create(NewCallee, NewArgs.begin(), NewArgs.end(),
10430 Caller->getName(), Caller);
10431 if (cast<CallInst>(Caller)->isTailCall())
10432 cast<CallInst>(NewCaller)->setTailCall();
10433 cast<CallInst>(NewCaller)->
10434 setCallingConv(cast<CallInst>(Caller)->getCallingConv());
10435 cast<CallInst>(NewCaller)->setAttributes(NewPAL);
10437 if (!Caller->getType()->isVoidTy())
10438 Caller->replaceAllUsesWith(NewCaller);
10439 Caller->eraseFromParent();
10440 Worklist.Remove(Caller);
10445 // Replace the trampoline call with a direct call. Since there is no 'nest'
10446 // parameter, there is no need to adjust the argument list. Let the generic
10447 // code sort out any function type mismatches.
10448 Constant *NewCallee =
10449 NestF->getType() == PTy ? NestF :
10450 ConstantExpr::getBitCast(NestF, PTy);
10451 CS.setCalledFunction(NewCallee);
10452 return CS.getInstruction();
10455 /// FoldPHIArgBinOpIntoPHI - If we have something like phi [add (a,b), add(a,c)]
10456 /// and if a/b/c and the add's all have a single use, turn this into a phi
10457 /// and a single binop.
10458 Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
10459 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
10460 assert(isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst));
10461 unsigned Opc = FirstInst->getOpcode();
10462 Value *LHSVal = FirstInst->getOperand(0);
10463 Value *RHSVal = FirstInst->getOperand(1);
10465 const Type *LHSType = LHSVal->getType();
10466 const Type *RHSType = RHSVal->getType();
10468 // Scan to see if all operands are the same opcode, and all have one use.
10469 for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
10470 Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
10471 if (!I || I->getOpcode() != Opc || !I->hasOneUse() ||
10472 // Verify type of the LHS matches so we don't fold cmp's of different
10473 // types or GEP's with different index types.
10474 I->getOperand(0)->getType() != LHSType ||
10475 I->getOperand(1)->getType() != RHSType)
10478 // If they are CmpInst instructions, check their predicates
10479 if (Opc == Instruction::ICmp || Opc == Instruction::FCmp)
10480 if (cast<CmpInst>(I)->getPredicate() !=
10481 cast<CmpInst>(FirstInst)->getPredicate())
10484 // Keep track of which operand needs a phi node.
10485 if (I->getOperand(0) != LHSVal) LHSVal = 0;
10486 if (I->getOperand(1) != RHSVal) RHSVal = 0;
10489 // If both LHS and RHS would need a PHI, don't do this transformation,
10490 // because it would increase the number of PHIs entering the block,
10491 // which leads to higher register pressure. This is especially
10492 // bad when the PHIs are in the header of a loop.
10493 if (!LHSVal && !RHSVal)
10496 // Otherwise, this is safe to transform!
10498 Value *InLHS = FirstInst->getOperand(0);
10499 Value *InRHS = FirstInst->getOperand(1);
10500 PHINode *NewLHS = 0, *NewRHS = 0;
10502 NewLHS = PHINode::Create(LHSType,
10503 FirstInst->getOperand(0)->getName() + ".pn");
10504 NewLHS->reserveOperandSpace(PN.getNumOperands()/2);
10505 NewLHS->addIncoming(InLHS, PN.getIncomingBlock(0));
10506 InsertNewInstBefore(NewLHS, PN);
10511 NewRHS = PHINode::Create(RHSType,
10512 FirstInst->getOperand(1)->getName() + ".pn");
10513 NewRHS->reserveOperandSpace(PN.getNumOperands()/2);
10514 NewRHS->addIncoming(InRHS, PN.getIncomingBlock(0));
10515 InsertNewInstBefore(NewRHS, PN);
10519 // Add all operands to the new PHIs.
10520 if (NewLHS || NewRHS) {
10521 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
10522 Instruction *InInst = cast<Instruction>(PN.getIncomingValue(i));
10524 Value *NewInLHS = InInst->getOperand(0);
10525 NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i));
10528 Value *NewInRHS = InInst->getOperand(1);
10529 NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i));
10534 if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
10535 return BinaryOperator::Create(BinOp->getOpcode(), LHSVal, RHSVal);
10536 CmpInst *CIOp = cast<CmpInst>(FirstInst);
10537 return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
10541 Instruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) {
10542 GetElementPtrInst *FirstInst =cast<GetElementPtrInst>(PN.getIncomingValue(0));
10544 SmallVector<Value*, 16> FixedOperands(FirstInst->op_begin(),
10545 FirstInst->op_end());
10546 // This is true if all GEP bases are allocas and if all indices into them are
10548 bool AllBasePointersAreAllocas = true;
10550 // We don't want to replace this phi if the replacement would require
10551 // more than one phi, which leads to higher register pressure. This is
10552 // especially bad when the PHIs are in the header of a loop.
10553 bool NeededPhi = false;
10555 // Scan to see if all operands are the same opcode, and all have one use.
10556 for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
10557 GetElementPtrInst *GEP= dyn_cast<GetElementPtrInst>(PN.getIncomingValue(i));
10558 if (!GEP || !GEP->hasOneUse() || GEP->getType() != FirstInst->getType() ||
10559 GEP->getNumOperands() != FirstInst->getNumOperands())
10562 // Keep track of whether or not all GEPs are of alloca pointers.
10563 if (AllBasePointersAreAllocas &&
10564 (!isa<AllocaInst>(GEP->getOperand(0)) ||
10565 !GEP->hasAllConstantIndices()))
10566 AllBasePointersAreAllocas = false;
10568 // Compare the operand lists.
10569 for (unsigned op = 0, e = FirstInst->getNumOperands(); op != e; ++op) {
10570 if (FirstInst->getOperand(op) == GEP->getOperand(op))
10573 // Don't merge two GEPs when two operands differ (introducing phi nodes)
10574 // if one of the PHIs has a constant for the index. The index may be
10575 // substantially cheaper to compute for the constants, so making it a
10576 // variable index could pessimize the path. This also handles the case
10577 // for struct indices, which must always be constant.
10578 if (isa<ConstantInt>(FirstInst->getOperand(op)) ||
10579 isa<ConstantInt>(GEP->getOperand(op)))
10582 if (FirstInst->getOperand(op)->getType() !=GEP->getOperand(op)->getType())
10585 // If we already needed a PHI for an earlier operand, and another operand
10586 // also requires a PHI, we'd be introducing more PHIs than we're
10587 // eliminating, which increases register pressure on entry to the PHI's
10592 FixedOperands[op] = 0; // Needs a PHI.
10597 // If all of the base pointers of the PHI'd GEPs are from allocas, don't
10598 // bother doing this transformation. At best, this will just save a bit of
10599 // offset calculation, but all the predecessors will have to materialize the
10600 // stack address into a register anyway. We'd actually rather *clone* the
10601 // load up into the predecessors so that we have a load of a gep of an alloca,
10602 // which can usually all be folded into the load.
10603 if (AllBasePointersAreAllocas)
10606 // Otherwise, this is safe to transform. Insert PHI nodes for each operand
10607 // that is variable.
10608 SmallVector<PHINode*, 16> OperandPhis(FixedOperands.size());
10610 bool HasAnyPHIs = false;
10611 for (unsigned i = 0, e = FixedOperands.size(); i != e; ++i) {
10612 if (FixedOperands[i]) continue; // operand doesn't need a phi.
10613 Value *FirstOp = FirstInst->getOperand(i);
10614 PHINode *NewPN = PHINode::Create(FirstOp->getType(),
10615 FirstOp->getName()+".pn");
10616 InsertNewInstBefore(NewPN, PN);
10618 NewPN->reserveOperandSpace(e);
10619 NewPN->addIncoming(FirstOp, PN.getIncomingBlock(0));
10620 OperandPhis[i] = NewPN;
10621 FixedOperands[i] = NewPN;
10626 // Add all operands to the new PHIs.
10628 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
10629 GetElementPtrInst *InGEP =cast<GetElementPtrInst>(PN.getIncomingValue(i));
10630 BasicBlock *InBB = PN.getIncomingBlock(i);
10632 for (unsigned op = 0, e = OperandPhis.size(); op != e; ++op)
10633 if (PHINode *OpPhi = OperandPhis[op])
10634 OpPhi->addIncoming(InGEP->getOperand(op), InBB);
10638 Value *Base = FixedOperands[0];
10639 return cast<GEPOperator>(FirstInst)->isInBounds() ?
10640 GetElementPtrInst::CreateInBounds(Base, FixedOperands.begin()+1,
10641 FixedOperands.end()) :
10642 GetElementPtrInst::Create(Base, FixedOperands.begin()+1,
10643 FixedOperands.end());
10647 /// isSafeAndProfitableToSinkLoad - Return true if we know that it is safe to
10648 /// sink the load out of the block that defines it. This means that it must be
10649 /// obvious the value of the load is not changed from the point of the load to
10650 /// the end of the block it is in.
10652 /// Finally, it is safe, but not profitable, to sink a load targetting a
10653 /// non-address-taken alloca. Doing so will cause us to not promote the alloca
10655 static bool isSafeAndProfitableToSinkLoad(LoadInst *L) {
10656 BasicBlock::iterator BBI = L, E = L->getParent()->end();
10658 for (++BBI; BBI != E; ++BBI)
10659 if (BBI->mayWriteToMemory())
10662 // Check for non-address taken alloca. If not address-taken already, it isn't
10663 // profitable to do this xform.
10664 if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) {
10665 bool isAddressTaken = false;
10666 for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
10668 if (isa<LoadInst>(UI)) continue;
10669 if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
10670 // If storing TO the alloca, then the address isn't taken.
10671 if (SI->getOperand(1) == AI) continue;
10673 isAddressTaken = true;
10677 if (!isAddressTaken && AI->isStaticAlloca())
10681 // If this load is a load from a GEP with a constant offset from an alloca,
10682 // then we don't want to sink it. In its present form, it will be
10683 // load [constant stack offset]. Sinking it will cause us to have to
10684 // materialize the stack addresses in each predecessor in a register only to
10685 // do a shared load from register in the successor.
10686 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(L->getOperand(0)))
10687 if (AllocaInst *AI = dyn_cast<AllocaInst>(GEP->getOperand(0)))
10688 if (AI->isStaticAlloca() && GEP->hasAllConstantIndices())
10695 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
10696 // operator and they all are only used by the PHI, PHI together their
10697 // inputs, and do the operation once, to the result of the PHI.
10698 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
10699 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
10701 // Scan the instruction, looking for input operations that can be folded away.
10702 // If all input operands to the phi are the same instruction (e.g. a cast from
10703 // the same type or "+42") we can pull the operation through the PHI, reducing
10704 // code size and simplifying code.
10705 Constant *ConstantOp = 0;
10706 const Type *CastSrcTy = 0;
10707 bool isVolatile = false;
10708 if (isa<CastInst>(FirstInst)) {
10709 CastSrcTy = FirstInst->getOperand(0)->getType();
10710 } else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
10711 // Can fold binop, compare or shift here if the RHS is a constant,
10712 // otherwise call FoldPHIArgBinOpIntoPHI.
10713 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
10714 if (ConstantOp == 0)
10715 return FoldPHIArgBinOpIntoPHI(PN);
10716 } else if (LoadInst *LI = dyn_cast<LoadInst>(FirstInst)) {
10717 isVolatile = LI->isVolatile();
10718 // We can't sink the load if the loaded value could be modified between the
10719 // load and the PHI.
10720 if (LI->getParent() != PN.getIncomingBlock(0) ||
10721 !isSafeAndProfitableToSinkLoad(LI))
10724 // If the PHI is of volatile loads and the load block has multiple
10725 // successors, sinking it would remove a load of the volatile value from
10726 // the path through the other successor.
10728 LI->getParent()->getTerminator()->getNumSuccessors() != 1)
10731 } else if (isa<GetElementPtrInst>(FirstInst)) {
10732 return FoldPHIArgGEPIntoPHI(PN);
10734 return 0; // Cannot fold this operation.
10737 // Check to see if all arguments are the same operation.
10738 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
10739 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
10740 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
10741 if (!I->hasOneUse() || !I->isSameOperationAs(FirstInst))
10744 if (I->getOperand(0)->getType() != CastSrcTy)
10745 return 0; // Cast operation must match.
10746 } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
10747 // We can't sink the load if the loaded value could be modified between
10748 // the load and the PHI.
10749 if (LI->isVolatile() != isVolatile ||
10750 LI->getParent() != PN.getIncomingBlock(i) ||
10751 !isSafeAndProfitableToSinkLoad(LI))
10754 // If the PHI is of volatile loads and the load block has multiple
10755 // successors, sinking it would remove a load of the volatile value from
10756 // the path through the other successor.
10758 LI->getParent()->getTerminator()->getNumSuccessors() != 1)
10761 } else if (I->getOperand(1) != ConstantOp) {
10766 // Okay, they are all the same operation. Create a new PHI node of the
10767 // correct type, and PHI together all of the LHS's of the instructions.
10768 PHINode *NewPN = PHINode::Create(FirstInst->getOperand(0)->getType(),
10769 PN.getName()+".in");
10770 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
10772 Value *InVal = FirstInst->getOperand(0);
10773 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
10775 // Add all operands to the new PHI.
10776 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
10777 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
10778 if (NewInVal != InVal)
10780 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
10785 // The new PHI unions all of the same values together. This is really
10786 // common, so we handle it intelligently here for compile-time speed.
10790 InsertNewInstBefore(NewPN, PN);
10794 // Insert and return the new operation.
10795 if (CastInst* FirstCI = dyn_cast<CastInst>(FirstInst))
10796 return CastInst::Create(FirstCI->getOpcode(), PhiVal, PN.getType());
10797 if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
10798 return BinaryOperator::Create(BinOp->getOpcode(), PhiVal, ConstantOp);
10799 if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
10800 return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
10801 PhiVal, ConstantOp);
10802 assert(isa<LoadInst>(FirstInst) && "Unknown operation");
10804 // If this was a volatile load that we are merging, make sure to loop through
10805 // and mark all the input loads as non-volatile. If we don't do this, we will
10806 // insert a new volatile load and the old ones will not be deletable.
10808 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
10809 cast<LoadInst>(PN.getIncomingValue(i))->setVolatile(false);
10811 return new LoadInst(PhiVal, "", isVolatile);
10814 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
10816 static bool DeadPHICycle(PHINode *PN,
10817 SmallPtrSet<PHINode*, 16> &PotentiallyDeadPHIs) {
10818 if (PN->use_empty()) return true;
10819 if (!PN->hasOneUse()) return false;
10821 // Remember this node, and if we find the cycle, return.
10822 if (!PotentiallyDeadPHIs.insert(PN))
10825 // Don't scan crazily complex things.
10826 if (PotentiallyDeadPHIs.size() == 16)
10829 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
10830 return DeadPHICycle(PU, PotentiallyDeadPHIs);
10835 /// PHIsEqualValue - Return true if this phi node is always equal to
10836 /// NonPhiInVal. This happens with mutually cyclic phi nodes like:
10837 /// z = some value; x = phi (y, z); y = phi (x, z)
10838 static bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal,
10839 SmallPtrSet<PHINode*, 16> &ValueEqualPHIs) {
10840 // See if we already saw this PHI node.
10841 if (!ValueEqualPHIs.insert(PN))
10844 // Don't scan crazily complex things.
10845 if (ValueEqualPHIs.size() == 16)
10848 // Scan the operands to see if they are either phi nodes or are equal to
10850 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
10851 Value *Op = PN->getIncomingValue(i);
10852 if (PHINode *OpPN = dyn_cast<PHINode>(Op)) {
10853 if (!PHIsEqualValue(OpPN, NonPhiInVal, ValueEqualPHIs))
10855 } else if (Op != NonPhiInVal)
10863 // PHINode simplification
10865 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
10866 // If LCSSA is around, don't mess with Phi nodes
10867 if (MustPreserveLCSSA) return 0;
10869 if (Value *V = PN.hasConstantValue())
10870 return ReplaceInstUsesWith(PN, V);
10872 // If all PHI operands are the same operation, pull them through the PHI,
10873 // reducing code size.
10874 if (isa<Instruction>(PN.getIncomingValue(0)) &&
10875 isa<Instruction>(PN.getIncomingValue(1)) &&
10876 cast<Instruction>(PN.getIncomingValue(0))->getOpcode() ==
10877 cast<Instruction>(PN.getIncomingValue(1))->getOpcode() &&
10878 // FIXME: The hasOneUse check will fail for PHIs that use the value more
10879 // than themselves more than once.
10880 PN.getIncomingValue(0)->hasOneUse())
10881 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
10884 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
10885 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
10886 // PHI)... break the cycle.
10887 if (PN.hasOneUse()) {
10888 Instruction *PHIUser = cast<Instruction>(PN.use_back());
10889 if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) {
10890 SmallPtrSet<PHINode*, 16> PotentiallyDeadPHIs;
10891 PotentiallyDeadPHIs.insert(&PN);
10892 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
10893 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
10896 // If this phi has a single use, and if that use just computes a value for
10897 // the next iteration of a loop, delete the phi. This occurs with unused
10898 // induction variables, e.g. "for (int j = 0; ; ++j);". Detecting this
10899 // common case here is good because the only other things that catch this
10900 // are induction variable analysis (sometimes) and ADCE, which is only run
10902 if (PHIUser->hasOneUse() &&
10903 (isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) &&
10904 PHIUser->use_back() == &PN) {
10905 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
10909 // We sometimes end up with phi cycles that non-obviously end up being the
10910 // same value, for example:
10911 // z = some value; x = phi (y, z); y = phi (x, z)
10912 // where the phi nodes don't necessarily need to be in the same block. Do a
10913 // quick check to see if the PHI node only contains a single non-phi value, if
10914 // so, scan to see if the phi cycle is actually equal to that value.
10916 unsigned InValNo = 0, NumOperandVals = PN.getNumIncomingValues();
10917 // Scan for the first non-phi operand.
10918 while (InValNo != NumOperandVals &&
10919 isa<PHINode>(PN.getIncomingValue(InValNo)))
10922 if (InValNo != NumOperandVals) {
10923 Value *NonPhiInVal = PN.getOperand(InValNo);
10925 // Scan the rest of the operands to see if there are any conflicts, if so
10926 // there is no need to recursively scan other phis.
10927 for (++InValNo; InValNo != NumOperandVals; ++InValNo) {
10928 Value *OpVal = PN.getIncomingValue(InValNo);
10929 if (OpVal != NonPhiInVal && !isa<PHINode>(OpVal))
10933 // If we scanned over all operands, then we have one unique value plus
10934 // phi values. Scan PHI nodes to see if they all merge in each other or
10936 if (InValNo == NumOperandVals) {
10937 SmallPtrSet<PHINode*, 16> ValueEqualPHIs;
10938 if (PHIsEqualValue(&PN, NonPhiInVal, ValueEqualPHIs))
10939 return ReplaceInstUsesWith(PN, NonPhiInVal);
10946 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
10947 Value *PtrOp = GEP.getOperand(0);
10948 // Eliminate 'getelementptr %P, i32 0' and 'getelementptr %P', they are noops.
10949 if (GEP.getNumOperands() == 1)
10950 return ReplaceInstUsesWith(GEP, PtrOp);
10952 if (isa<UndefValue>(GEP.getOperand(0)))
10953 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
10955 bool HasZeroPointerIndex = false;
10956 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
10957 HasZeroPointerIndex = C->isNullValue();
10959 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
10960 return ReplaceInstUsesWith(GEP, PtrOp);
10962 // Eliminate unneeded casts for indices.
10964 bool MadeChange = false;
10965 unsigned PtrSize = TD->getPointerSizeInBits();
10967 gep_type_iterator GTI = gep_type_begin(GEP);
10968 for (User::op_iterator I = GEP.op_begin() + 1, E = GEP.op_end();
10969 I != E; ++I, ++GTI) {
10970 if (!isa<SequentialType>(*GTI)) continue;
10972 // If we are using a wider index than needed for this platform, shrink it
10973 // to what we need. If narrower, sign-extend it to what we need. This
10974 // explicit cast can make subsequent optimizations more obvious.
10975 unsigned OpBits = cast<IntegerType>((*I)->getType())->getBitWidth();
10976 if (OpBits == PtrSize)
10979 *I = Builder->CreateIntCast(*I, TD->getIntPtrType(GEP.getContext()),true);
10982 if (MadeChange) return &GEP;
10985 // Combine Indices - If the source pointer to this getelementptr instruction
10986 // is a getelementptr instruction, combine the indices of the two
10987 // getelementptr instructions into a single instruction.
10989 if (GEPOperator *Src = dyn_cast<GEPOperator>(PtrOp)) {
10990 // Note that if our source is a gep chain itself that we wait for that
10991 // chain to be resolved before we perform this transformation. This
10992 // avoids us creating a TON of code in some cases.
10994 if (GetElementPtrInst *SrcGEP =
10995 dyn_cast<GetElementPtrInst>(Src->getOperand(0)))
10996 if (SrcGEP->getNumOperands() == 2)
10997 return 0; // Wait until our source is folded to completion.
10999 SmallVector<Value*, 8> Indices;
11001 // Find out whether the last index in the source GEP is a sequential idx.
11002 bool EndsWithSequential = false;
11003 for (gep_type_iterator I = gep_type_begin(*Src), E = gep_type_end(*Src);
11005 EndsWithSequential = !isa<StructType>(*I);
11007 // Can we combine the two pointer arithmetics offsets?
11008 if (EndsWithSequential) {
11009 // Replace: gep (gep %P, long B), long A, ...
11010 // With: T = long A+B; gep %P, T, ...
11013 Value *SO1 = Src->getOperand(Src->getNumOperands()-1);
11014 Value *GO1 = GEP.getOperand(1);
11015 if (SO1 == Constant::getNullValue(SO1->getType())) {
11017 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
11020 // If they aren't the same type, then the input hasn't been processed
11021 // by the loop above yet (which canonicalizes sequential index types to
11022 // intptr_t). Just avoid transforming this until the input has been
11024 if (SO1->getType() != GO1->getType())
11026 Sum = Builder->CreateAdd(SO1, GO1, PtrOp->getName()+".sum");
11029 // Update the GEP in place if possible.
11030 if (Src->getNumOperands() == 2) {
11031 GEP.setOperand(0, Src->getOperand(0));
11032 GEP.setOperand(1, Sum);
11035 Indices.append(Src->op_begin()+1, Src->op_end()-1);
11036 Indices.push_back(Sum);
11037 Indices.append(GEP.op_begin()+2, GEP.op_end());
11038 } else if (isa<Constant>(*GEP.idx_begin()) &&
11039 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
11040 Src->getNumOperands() != 1) {
11041 // Otherwise we can do the fold if the first index of the GEP is a zero
11042 Indices.append(Src->op_begin()+1, Src->op_end());
11043 Indices.append(GEP.idx_begin()+1, GEP.idx_end());
11046 if (!Indices.empty())
11047 return (cast<GEPOperator>(&GEP)->isInBounds() &&
11048 Src->isInBounds()) ?
11049 GetElementPtrInst::CreateInBounds(Src->getOperand(0), Indices.begin(),
11050 Indices.end(), GEP.getName()) :
11051 GetElementPtrInst::Create(Src->getOperand(0), Indices.begin(),
11052 Indices.end(), GEP.getName());
11055 // Handle gep(bitcast x) and gep(gep x, 0, 0, 0).
11056 if (Value *X = getBitCastOperand(PtrOp)) {
11057 assert(isa<PointerType>(X->getType()) && "Must be cast from pointer");
11059 // If the input bitcast is actually "bitcast(bitcast(x))", then we don't
11060 // want to change the gep until the bitcasts are eliminated.
11061 if (getBitCastOperand(X)) {
11062 Worklist.AddValue(PtrOp);
11066 // Transform: GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ...
11067 // into : GEP [10 x i8]* X, i32 0, ...
11069 // Likewise, transform: GEP (bitcast i8* X to [0 x i8]*), i32 0, ...
11070 // into : GEP i8* X, ...
11072 // This occurs when the program declares an array extern like "int X[];"
11073 if (HasZeroPointerIndex) {
11074 const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
11075 const PointerType *XTy = cast<PointerType>(X->getType());
11076 if (const ArrayType *CATy =
11077 dyn_cast<ArrayType>(CPTy->getElementType())) {
11078 // GEP (bitcast i8* X to [0 x i8]*), i32 0, ... ?
11079 if (CATy->getElementType() == XTy->getElementType()) {
11080 // -> GEP i8* X, ...
11081 SmallVector<Value*, 8> Indices(GEP.idx_begin()+1, GEP.idx_end());
11082 return cast<GEPOperator>(&GEP)->isInBounds() ?
11083 GetElementPtrInst::CreateInBounds(X, Indices.begin(), Indices.end(),
11085 GetElementPtrInst::Create(X, Indices.begin(), Indices.end(),
11089 if (const ArrayType *XATy = dyn_cast<ArrayType>(XTy->getElementType())){
11090 // GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ... ?
11091 if (CATy->getElementType() == XATy->getElementType()) {
11092 // -> GEP [10 x i8]* X, i32 0, ...
11093 // At this point, we know that the cast source type is a pointer
11094 // to an array of the same type as the destination pointer
11095 // array. Because the array type is never stepped over (there
11096 // is a leading zero) we can fold the cast into this GEP.
11097 GEP.setOperand(0, X);
11102 } else if (GEP.getNumOperands() == 2) {
11103 // Transform things like:
11104 // %t = getelementptr i32* bitcast ([2 x i32]* %str to i32*), i32 %V
11105 // into: %t1 = getelementptr [2 x i32]* %str, i32 0, i32 %V; bitcast
11106 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
11107 const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
11108 if (TD && isa<ArrayType>(SrcElTy) &&
11109 TD->getTypeAllocSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
11110 TD->getTypeAllocSize(ResElTy)) {
11112 Idx[0] = Constant::getNullValue(Type::getInt32Ty(*Context));
11113 Idx[1] = GEP.getOperand(1);
11114 Value *NewGEP = cast<GEPOperator>(&GEP)->isInBounds() ?
11115 Builder->CreateInBoundsGEP(X, Idx, Idx + 2, GEP.getName()) :
11116 Builder->CreateGEP(X, Idx, Idx + 2, GEP.getName());
11117 // V and GEP are both pointer types --> BitCast
11118 return new BitCastInst(NewGEP, GEP.getType());
11121 // Transform things like:
11122 // getelementptr i8* bitcast ([100 x double]* X to i8*), i32 %tmp
11123 // (where tmp = 8*tmp2) into:
11124 // getelementptr [100 x double]* %arr, i32 0, i32 %tmp2; bitcast
11126 if (TD && isa<ArrayType>(SrcElTy) && ResElTy == Type::getInt8Ty(*Context)) {
11127 uint64_t ArrayEltSize =
11128 TD->getTypeAllocSize(cast<ArrayType>(SrcElTy)->getElementType());
11130 // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
11131 // allow either a mul, shift, or constant here.
11133 ConstantInt *Scale = 0;
11134 if (ArrayEltSize == 1) {
11135 NewIdx = GEP.getOperand(1);
11136 Scale = ConstantInt::get(cast<IntegerType>(NewIdx->getType()), 1);
11137 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
11138 NewIdx = ConstantInt::get(CI->getType(), 1);
11140 } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
11141 if (Inst->getOpcode() == Instruction::Shl &&
11142 isa<ConstantInt>(Inst->getOperand(1))) {
11143 ConstantInt *ShAmt = cast<ConstantInt>(Inst->getOperand(1));
11144 uint32_t ShAmtVal = ShAmt->getLimitedValue(64);
11145 Scale = ConstantInt::get(cast<IntegerType>(Inst->getType()),
11147 NewIdx = Inst->getOperand(0);
11148 } else if (Inst->getOpcode() == Instruction::Mul &&
11149 isa<ConstantInt>(Inst->getOperand(1))) {
11150 Scale = cast<ConstantInt>(Inst->getOperand(1));
11151 NewIdx = Inst->getOperand(0);
11155 // If the index will be to exactly the right offset with the scale taken
11156 // out, perform the transformation. Note, we don't know whether Scale is
11157 // signed or not. We'll use unsigned version of division/modulo
11158 // operation after making sure Scale doesn't have the sign bit set.
11159 if (ArrayEltSize && Scale && Scale->getSExtValue() >= 0LL &&
11160 Scale->getZExtValue() % ArrayEltSize == 0) {
11161 Scale = ConstantInt::get(Scale->getType(),
11162 Scale->getZExtValue() / ArrayEltSize);
11163 if (Scale->getZExtValue() != 1) {
11164 Constant *C = ConstantExpr::getIntegerCast(Scale, NewIdx->getType(),
11166 NewIdx = Builder->CreateMul(NewIdx, C, "idxscale");
11169 // Insert the new GEP instruction.
11171 Idx[0] = Constant::getNullValue(Type::getInt32Ty(*Context));
11173 Value *NewGEP = cast<GEPOperator>(&GEP)->isInBounds() ?
11174 Builder->CreateInBoundsGEP(X, Idx, Idx + 2, GEP.getName()) :
11175 Builder->CreateGEP(X, Idx, Idx + 2, GEP.getName());
11176 // The NewGEP must be pointer typed, so must the old one -> BitCast
11177 return new BitCastInst(NewGEP, GEP.getType());
11183 /// See if we can simplify:
11184 /// X = bitcast A* to B*
11185 /// Y = gep X, <...constant indices...>
11186 /// into a gep of the original struct. This is important for SROA and alias
11187 /// analysis of unions. If "A" is also a bitcast, wait for A/X to be merged.
11188 if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {
11190 !isa<BitCastInst>(BCI->getOperand(0)) && GEP.hasAllConstantIndices()) {
11191 // Determine how much the GEP moves the pointer. We are guaranteed to get
11192 // a constant back from EmitGEPOffset.
11193 ConstantInt *OffsetV =
11194 cast<ConstantInt>(EmitGEPOffset(&GEP, GEP, *this));
11195 int64_t Offset = OffsetV->getSExtValue();
11197 // If this GEP instruction doesn't move the pointer, just replace the GEP
11198 // with a bitcast of the real input to the dest type.
11200 // If the bitcast is of an allocation, and the allocation will be
11201 // converted to match the type of the cast, don't touch this.
11202 if (isa<AllocationInst>(BCI->getOperand(0)) ||
11203 isMalloc(BCI->getOperand(0))) {
11204 // See if the bitcast simplifies, if so, don't nuke this GEP yet.
11205 if (Instruction *I = visitBitCast(*BCI)) {
11208 BCI->getParent()->getInstList().insert(BCI, I);
11209 ReplaceInstUsesWith(*BCI, I);
11214 return new BitCastInst(BCI->getOperand(0), GEP.getType());
11217 // Otherwise, if the offset is non-zero, we need to find out if there is a
11218 // field at Offset in 'A's type. If so, we can pull the cast through the
11220 SmallVector<Value*, 8> NewIndices;
11222 cast<PointerType>(BCI->getOperand(0)->getType())->getElementType();
11223 if (FindElementAtOffset(InTy, Offset, NewIndices, TD, Context)) {
11224 Value *NGEP = cast<GEPOperator>(&GEP)->isInBounds() ?
11225 Builder->CreateInBoundsGEP(BCI->getOperand(0), NewIndices.begin(),
11226 NewIndices.end()) :
11227 Builder->CreateGEP(BCI->getOperand(0), NewIndices.begin(),
11230 if (NGEP->getType() == GEP.getType())
11231 return ReplaceInstUsesWith(GEP, NGEP);
11232 NGEP->takeName(&GEP);
11233 return new BitCastInst(NGEP, GEP.getType());
11241 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
11242 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
11243 if (AI.isArrayAllocation()) { // Check C != 1
11244 if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) {
11245 const Type *NewTy =
11246 ArrayType::get(AI.getAllocatedType(), C->getZExtValue());
11247 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
11248 AllocationInst *New = Builder->CreateAlloca(NewTy, 0, AI.getName());
11249 New->setAlignment(AI.getAlignment());
11251 // Scan to the end of the allocation instructions, to skip over a block of
11252 // allocas if possible...also skip interleaved debug info
11254 BasicBlock::iterator It = New;
11255 while (isa<AllocationInst>(*It) || isa<DbgInfoIntrinsic>(*It)) ++It;
11257 // Now that I is pointing to the first non-allocation-inst in the block,
11258 // insert our getelementptr instruction...
11260 Value *NullIdx = Constant::getNullValue(Type::getInt32Ty(*Context));
11264 Value *V = GetElementPtrInst::CreateInBounds(New, Idx, Idx + 2,
11265 New->getName()+".sub", It);
11267 // Now make everything use the getelementptr instead of the original
11269 return ReplaceInstUsesWith(AI, V);
11270 } else if (isa<UndefValue>(AI.getArraySize())) {
11271 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
11275 if (TD && isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized()) {
11276 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
11277 // Note that we only do this for alloca's, because malloc should allocate
11278 // and return a unique pointer, even for a zero byte allocation.
11279 if (TD->getTypeAllocSize(AI.getAllocatedType()) == 0)
11280 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
11282 // If the alignment is 0 (unspecified), assign it the preferred alignment.
11283 if (AI.getAlignment() == 0)
11284 AI.setAlignment(TD->getPrefTypeAlignment(AI.getAllocatedType()));
11290 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
11291 Value *Op = FI.getOperand(0);
11293 // free undef -> unreachable.
11294 if (isa<UndefValue>(Op)) {
11295 // Insert a new store to null because we cannot modify the CFG here.
11296 new StoreInst(ConstantInt::getTrue(*Context),
11297 UndefValue::get(Type::getInt1PtrTy(*Context)), &FI);
11298 return EraseInstFromFunction(FI);
11301 // If we have 'free null' delete the instruction. This can happen in stl code
11302 // when lots of inlining happens.
11303 if (isa<ConstantPointerNull>(Op))
11304 return EraseInstFromFunction(FI);
11306 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
11307 if (BitCastInst *CI = dyn_cast<BitCastInst>(Op)) {
11308 FI.setOperand(0, CI->getOperand(0));
11312 // Change free (gep X, 0,0,0,0) into free(X)
11313 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
11314 if (GEPI->hasAllZeroIndices()) {
11315 Worklist.Add(GEPI);
11316 FI.setOperand(0, GEPI->getOperand(0));
11321 if (isMalloc(Op)) {
11322 if (CallInst* CI = extractMallocCallFromBitCast(Op)) {
11323 if (Op->hasOneUse() && CI->hasOneUse()) {
11324 EraseInstFromFunction(FI);
11325 EraseInstFromFunction(*CI);
11326 return EraseInstFromFunction(*cast<Instruction>(Op));
11329 // Op is a call to malloc
11330 if (Op->hasOneUse()) {
11331 EraseInstFromFunction(FI);
11332 return EraseInstFromFunction(*cast<Instruction>(Op));
11341 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
11342 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI,
11343 const TargetData *TD) {
11344 User *CI = cast<User>(LI.getOperand(0));
11345 Value *CastOp = CI->getOperand(0);
11346 LLVMContext *Context = IC.getContext();
11349 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(CI)) {
11350 // Instead of loading constant c string, use corresponding integer value
11351 // directly if string length is small enough.
11353 if (GetConstantStringInfo(CE->getOperand(0), Str) && !Str.empty()) {
11354 unsigned len = Str.length();
11355 const Type *Ty = cast<PointerType>(CE->getType())->getElementType();
11356 unsigned numBits = Ty->getPrimitiveSizeInBits();
11357 // Replace LI with immediate integer store.
11358 if ((numBits >> 3) == len + 1) {
11359 APInt StrVal(numBits, 0);
11360 APInt SingleChar(numBits, 0);
11361 if (TD->isLittleEndian()) {
11362 for (signed i = len-1; i >= 0; i--) {
11363 SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
11364 StrVal = (StrVal << 8) | SingleChar;
11367 for (unsigned i = 0; i < len; i++) {
11368 SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
11369 StrVal = (StrVal << 8) | SingleChar;
11371 // Append NULL at the end.
11373 StrVal = (StrVal << 8) | SingleChar;
11375 Value *NL = ConstantInt::get(*Context, StrVal);
11376 return IC.ReplaceInstUsesWith(LI, NL);
11382 const PointerType *DestTy = cast<PointerType>(CI->getType());
11383 const Type *DestPTy = DestTy->getElementType();
11384 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
11386 // If the address spaces don't match, don't eliminate the cast.
11387 if (DestTy->getAddressSpace() != SrcTy->getAddressSpace())
11390 const Type *SrcPTy = SrcTy->getElementType();
11392 if (DestPTy->isInteger() || isa<PointerType>(DestPTy) ||
11393 isa<VectorType>(DestPTy)) {
11394 // If the source is an array, the code below will not succeed. Check to
11395 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
11397 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
11398 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
11399 if (ASrcTy->getNumElements() != 0) {
11401 Idxs[0] = Idxs[1] = Constant::getNullValue(Type::getInt32Ty(*Context));
11402 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2);
11403 SrcTy = cast<PointerType>(CastOp->getType());
11404 SrcPTy = SrcTy->getElementType();
11407 if (IC.getTargetData() &&
11408 (SrcPTy->isInteger() || isa<PointerType>(SrcPTy) ||
11409 isa<VectorType>(SrcPTy)) &&
11410 // Do not allow turning this into a load of an integer, which is then
11411 // casted to a pointer, this pessimizes pointer analysis a lot.
11412 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
11413 IC.getTargetData()->getTypeSizeInBits(SrcPTy) ==
11414 IC.getTargetData()->getTypeSizeInBits(DestPTy)) {
11416 // Okay, we are casting from one integer or pointer type to another of
11417 // the same size. Instead of casting the pointer before the load, cast
11418 // the result of the loaded value.
11420 IC.Builder->CreateLoad(CastOp, LI.isVolatile(), CI->getName());
11421 // Now cast the result of the load.
11422 return new BitCastInst(NewLoad, LI.getType());
11429 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
11430 Value *Op = LI.getOperand(0);
11432 // Attempt to improve the alignment.
11434 unsigned KnownAlign =
11435 GetOrEnforceKnownAlignment(Op, TD->getPrefTypeAlignment(LI.getType()));
11437 (LI.getAlignment() == 0 ? TD->getABITypeAlignment(LI.getType()) :
11438 LI.getAlignment()))
11439 LI.setAlignment(KnownAlign);
11442 // load (cast X) --> cast (load X) iff safe.
11443 if (isa<CastInst>(Op))
11444 if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
11447 // None of the following transforms are legal for volatile loads.
11448 if (LI.isVolatile()) return 0;
11450 // Do really simple store-to-load forwarding and load CSE, to catch cases
11451 // where there are several consequtive memory accesses to the same location,
11452 // separated by a few arithmetic operations.
11453 BasicBlock::iterator BBI = &LI;
11454 if (Value *AvailableVal = FindAvailableLoadedValue(Op, LI.getParent(), BBI,6))
11455 return ReplaceInstUsesWith(LI, AvailableVal);
11457 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
11458 const Value *GEPI0 = GEPI->getOperand(0);
11459 // TODO: Consider a target hook for valid address spaces for this xform.
11460 if (isa<ConstantPointerNull>(GEPI0) && GEPI->getPointerAddressSpace() == 0){
11461 // Insert a new store to null instruction before the load to indicate
11462 // that this code is not reachable. We do this instead of inserting
11463 // an unreachable instruction directly because we cannot modify the
11465 new StoreInst(UndefValue::get(LI.getType()),
11466 Constant::getNullValue(Op->getType()), &LI);
11467 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
11471 if (Constant *C = dyn_cast<Constant>(Op)) {
11472 // load null/undef -> undef
11473 // TODO: Consider a target hook for valid address spaces for this xform.
11474 if (isa<UndefValue>(C) ||
11475 (C->isNullValue() && LI.getPointerAddressSpace() == 0)) {
11476 // Insert a new store to null instruction before the load to indicate that
11477 // this code is not reachable. We do this instead of inserting an
11478 // unreachable instruction directly because we cannot modify the CFG.
11479 new StoreInst(UndefValue::get(LI.getType()),
11480 Constant::getNullValue(Op->getType()), &LI);
11481 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
11484 // Instcombine load (constant global) into the value loaded.
11485 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
11486 if (GV->isConstant() && GV->hasDefinitiveInitializer())
11487 return ReplaceInstUsesWith(LI, GV->getInitializer());
11489 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
11490 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op)) {
11491 if (CE->getOpcode() == Instruction::GetElementPtr) {
11492 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
11493 if (GV->isConstant() && GV->hasDefinitiveInitializer())
11495 ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
11496 return ReplaceInstUsesWith(LI, V);
11497 if (CE->getOperand(0)->isNullValue()) {
11498 // Insert a new store to null instruction before the load to indicate
11499 // that this code is not reachable. We do this instead of inserting
11500 // an unreachable instruction directly because we cannot modify the
11502 new StoreInst(UndefValue::get(LI.getType()),
11503 Constant::getNullValue(Op->getType()), &LI);
11504 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
11507 } else if (CE->isCast()) {
11508 if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
11514 // If this load comes from anywhere in a constant global, and if the global
11515 // is all undef or zero, we know what it loads.
11516 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op->getUnderlyingObject())){
11517 if (GV->isConstant() && GV->hasDefinitiveInitializer()) {
11518 if (GV->getInitializer()->isNullValue())
11519 return ReplaceInstUsesWith(LI, Constant::getNullValue(LI.getType()));
11520 else if (isa<UndefValue>(GV->getInitializer()))
11521 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
11525 if (Op->hasOneUse()) {
11526 // Change select and PHI nodes to select values instead of addresses: this
11527 // helps alias analysis out a lot, allows many others simplifications, and
11528 // exposes redundancy in the code.
11530 // Note that we cannot do the transformation unless we know that the
11531 // introduced loads cannot trap! Something like this is valid as long as
11532 // the condition is always false: load (select bool %C, int* null, int* %G),
11533 // but it would not be valid if we transformed it to load from null
11534 // unconditionally.
11536 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
11537 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
11538 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
11539 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
11540 Value *V1 = Builder->CreateLoad(SI->getOperand(1),
11541 SI->getOperand(1)->getName()+".val");
11542 Value *V2 = Builder->CreateLoad(SI->getOperand(2),
11543 SI->getOperand(2)->getName()+".val");
11544 return SelectInst::Create(SI->getCondition(), V1, V2);
11547 // load (select (cond, null, P)) -> load P
11548 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
11549 if (C->isNullValue()) {
11550 LI.setOperand(0, SI->getOperand(2));
11554 // load (select (cond, P, null)) -> load P
11555 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
11556 if (C->isNullValue()) {
11557 LI.setOperand(0, SI->getOperand(1));
11565 /// InstCombineStoreToCast - Fold store V, (cast P) -> store (cast V), P
11566 /// when possible. This makes it generally easy to do alias analysis and/or
11567 /// SROA/mem2reg of the memory object.
11568 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
11569 User *CI = cast<User>(SI.getOperand(1));
11570 Value *CastOp = CI->getOperand(0);
11572 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
11573 const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType());
11574 if (SrcTy == 0) return 0;
11576 const Type *SrcPTy = SrcTy->getElementType();
11578 if (!DestPTy->isInteger() && !isa<PointerType>(DestPTy))
11581 /// NewGEPIndices - If SrcPTy is an aggregate type, we can emit a "noop gep"
11582 /// to its first element. This allows us to handle things like:
11583 /// store i32 xxx, (bitcast {foo*, float}* %P to i32*)
11584 /// on 32-bit hosts.
11585 SmallVector<Value*, 4> NewGEPIndices;
11587 // If the source is an array, the code below will not succeed. Check to
11588 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
11590 if (isa<ArrayType>(SrcPTy) || isa<StructType>(SrcPTy)) {
11591 // Index through pointer.
11592 Constant *Zero = Constant::getNullValue(Type::getInt32Ty(*IC.getContext()));
11593 NewGEPIndices.push_back(Zero);
11596 if (const StructType *STy = dyn_cast<StructType>(SrcPTy)) {
11597 if (!STy->getNumElements()) /* Struct can be empty {} */
11599 NewGEPIndices.push_back(Zero);
11600 SrcPTy = STy->getElementType(0);
11601 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(SrcPTy)) {
11602 NewGEPIndices.push_back(Zero);
11603 SrcPTy = ATy->getElementType();
11609 SrcTy = PointerType::get(SrcPTy, SrcTy->getAddressSpace());
11612 if (!SrcPTy->isInteger() && !isa<PointerType>(SrcPTy))
11615 // If the pointers point into different address spaces or if they point to
11616 // values with different sizes, we can't do the transformation.
11617 if (!IC.getTargetData() ||
11618 SrcTy->getAddressSpace() !=
11619 cast<PointerType>(CI->getType())->getAddressSpace() ||
11620 IC.getTargetData()->getTypeSizeInBits(SrcPTy) !=
11621 IC.getTargetData()->getTypeSizeInBits(DestPTy))
11624 // Okay, we are casting from one integer or pointer type to another of
11625 // the same size. Instead of casting the pointer before
11626 // the store, cast the value to be stored.
11628 Value *SIOp0 = SI.getOperand(0);
11629 Instruction::CastOps opcode = Instruction::BitCast;
11630 const Type* CastSrcTy = SIOp0->getType();
11631 const Type* CastDstTy = SrcPTy;
11632 if (isa<PointerType>(CastDstTy)) {
11633 if (CastSrcTy->isInteger())
11634 opcode = Instruction::IntToPtr;
11635 } else if (isa<IntegerType>(CastDstTy)) {
11636 if (isa<PointerType>(SIOp0->getType()))
11637 opcode = Instruction::PtrToInt;
11640 // SIOp0 is a pointer to aggregate and this is a store to the first field,
11641 // emit a GEP to index into its first field.
11642 if (!NewGEPIndices.empty())
11643 CastOp = IC.Builder->CreateInBoundsGEP(CastOp, NewGEPIndices.begin(),
11644 NewGEPIndices.end());
11646 NewCast = IC.Builder->CreateCast(opcode, SIOp0, CastDstTy,
11647 SIOp0->getName()+".c");
11648 return new StoreInst(NewCast, CastOp);
11651 /// equivalentAddressValues - Test if A and B will obviously have the same
11652 /// value. This includes recognizing that %t0 and %t1 will have the same
11653 /// value in code like this:
11654 /// %t0 = getelementptr \@a, 0, 3
11655 /// store i32 0, i32* %t0
11656 /// %t1 = getelementptr \@a, 0, 3
11657 /// %t2 = load i32* %t1
11659 static bool equivalentAddressValues(Value *A, Value *B) {
11660 // Test if the values are trivially equivalent.
11661 if (A == B) return true;
11663 // Test if the values come form identical arithmetic instructions.
11664 // This uses isIdenticalToWhenDefined instead of isIdenticalTo because
11665 // its only used to compare two uses within the same basic block, which
11666 // means that they'll always either have the same value or one of them
11667 // will have an undefined value.
11668 if (isa<BinaryOperator>(A) ||
11669 isa<CastInst>(A) ||
11671 isa<GetElementPtrInst>(A))
11672 if (Instruction *BI = dyn_cast<Instruction>(B))
11673 if (cast<Instruction>(A)->isIdenticalToWhenDefined(BI))
11676 // Otherwise they may not be equivalent.
11680 // If this instruction has two uses, one of which is a llvm.dbg.declare,
11681 // return the llvm.dbg.declare.
11682 DbgDeclareInst *InstCombiner::hasOneUsePlusDeclare(Value *V) {
11683 if (!V->hasNUses(2))
11685 for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
11687 if (DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(UI))
11689 if (isa<BitCastInst>(UI) && UI->hasOneUse()) {
11690 if (DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(UI->use_begin()))
11697 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
11698 Value *Val = SI.getOperand(0);
11699 Value *Ptr = SI.getOperand(1);
11701 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
11702 EraseInstFromFunction(SI);
11707 // If the RHS is an alloca with a single use, zapify the store, making the
11709 // If the RHS is an alloca with a two uses, the other one being a
11710 // llvm.dbg.declare, zapify the store and the declare, making the
11711 // alloca dead. We must do this to prevent declare's from affecting
11713 if (!SI.isVolatile()) {
11714 if (Ptr->hasOneUse()) {
11715 if (isa<AllocaInst>(Ptr)) {
11716 EraseInstFromFunction(SI);
11720 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
11721 if (isa<AllocaInst>(GEP->getOperand(0))) {
11722 if (GEP->getOperand(0)->hasOneUse()) {
11723 EraseInstFromFunction(SI);
11727 if (DbgDeclareInst *DI = hasOneUsePlusDeclare(GEP->getOperand(0))) {
11728 EraseInstFromFunction(*DI);
11729 EraseInstFromFunction(SI);
11736 if (DbgDeclareInst *DI = hasOneUsePlusDeclare(Ptr)) {
11737 EraseInstFromFunction(*DI);
11738 EraseInstFromFunction(SI);
11744 // Attempt to improve the alignment.
11746 unsigned KnownAlign =
11747 GetOrEnforceKnownAlignment(Ptr, TD->getPrefTypeAlignment(Val->getType()));
11749 (SI.getAlignment() == 0 ? TD->getABITypeAlignment(Val->getType()) :
11750 SI.getAlignment()))
11751 SI.setAlignment(KnownAlign);
11754 // Do really simple DSE, to catch cases where there are several consecutive
11755 // stores to the same location, separated by a few arithmetic operations. This
11756 // situation often occurs with bitfield accesses.
11757 BasicBlock::iterator BBI = &SI;
11758 for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts;
11761 // Don't count debug info directives, lest they affect codegen,
11762 // and we skip pointer-to-pointer bitcasts, which are NOPs.
11763 // It is necessary for correctness to skip those that feed into a
11764 // llvm.dbg.declare, as these are not present when debugging is off.
11765 if (isa<DbgInfoIntrinsic>(BBI) ||
11766 (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType()))) {
11771 if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
11772 // Prev store isn't volatile, and stores to the same location?
11773 if (!PrevSI->isVolatile() &&equivalentAddressValues(PrevSI->getOperand(1),
11774 SI.getOperand(1))) {
11777 EraseInstFromFunction(*PrevSI);
11783 // If this is a load, we have to stop. However, if the loaded value is from
11784 // the pointer we're loading and is producing the pointer we're storing,
11785 // then *this* store is dead (X = load P; store X -> P).
11786 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
11787 if (LI == Val && equivalentAddressValues(LI->getOperand(0), Ptr) &&
11788 !SI.isVolatile()) {
11789 EraseInstFromFunction(SI);
11793 // Otherwise, this is a load from some other location. Stores before it
11794 // may not be dead.
11798 // Don't skip over loads or things that can modify memory.
11799 if (BBI->mayWriteToMemory() || BBI->mayReadFromMemory())
11804 if (SI.isVolatile()) return 0; // Don't hack volatile stores.
11806 // store X, null -> turns into 'unreachable' in SimplifyCFG
11807 if (isa<ConstantPointerNull>(Ptr) && SI.getPointerAddressSpace() == 0) {
11808 if (!isa<UndefValue>(Val)) {
11809 SI.setOperand(0, UndefValue::get(Val->getType()));
11810 if (Instruction *U = dyn_cast<Instruction>(Val))
11811 Worklist.Add(U); // Dropped a use.
11814 return 0; // Do not modify these!
11817 // store undef, Ptr -> noop
11818 if (isa<UndefValue>(Val)) {
11819 EraseInstFromFunction(SI);
11824 // If the pointer destination is a cast, see if we can fold the cast into the
11826 if (isa<CastInst>(Ptr))
11827 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
11829 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
11831 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
11835 // If this store is the last instruction in the basic block (possibly
11836 // excepting debug info instructions and the pointer bitcasts that feed
11837 // into them), and if the block ends with an unconditional branch, try
11838 // to move it to the successor block.
11842 } while (isa<DbgInfoIntrinsic>(BBI) ||
11843 (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType())));
11844 if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
11845 if (BI->isUnconditional())
11846 if (SimplifyStoreAtEndOfBlock(SI))
11847 return 0; // xform done!
11852 /// SimplifyStoreAtEndOfBlock - Turn things like:
11853 /// if () { *P = v1; } else { *P = v2 }
11854 /// into a phi node with a store in the successor.
11856 /// Simplify things like:
11857 /// *P = v1; if () { *P = v2; }
11858 /// into a phi node with a store in the successor.
11860 bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
11861 BasicBlock *StoreBB = SI.getParent();
11863 // Check to see if the successor block has exactly two incoming edges. If
11864 // so, see if the other predecessor contains a store to the same location.
11865 // if so, insert a PHI node (if needed) and move the stores down.
11866 BasicBlock *DestBB = StoreBB->getTerminator()->getSuccessor(0);
11868 // Determine whether Dest has exactly two predecessors and, if so, compute
11869 // the other predecessor.
11870 pred_iterator PI = pred_begin(DestBB);
11871 BasicBlock *OtherBB = 0;
11872 if (*PI != StoreBB)
11875 if (PI == pred_end(DestBB))
11878 if (*PI != StoreBB) {
11883 if (++PI != pred_end(DestBB))
11886 // Bail out if all the relevant blocks aren't distinct (this can happen,
11887 // for example, if SI is in an infinite loop)
11888 if (StoreBB == DestBB || OtherBB == DestBB)
11891 // Verify that the other block ends in a branch and is not otherwise empty.
11892 BasicBlock::iterator BBI = OtherBB->getTerminator();
11893 BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);
11894 if (!OtherBr || BBI == OtherBB->begin())
11897 // If the other block ends in an unconditional branch, check for the 'if then
11898 // else' case. there is an instruction before the branch.
11899 StoreInst *OtherStore = 0;
11900 if (OtherBr->isUnconditional()) {
11902 // Skip over debugging info.
11903 while (isa<DbgInfoIntrinsic>(BBI) ||
11904 (isa<BitCastInst>(BBI) && isa<PointerType>(BBI->getType()))) {
11905 if (BBI==OtherBB->begin())
11909 // If this isn't a store, or isn't a store to the same location, bail out.
11910 OtherStore = dyn_cast<StoreInst>(BBI);
11911 if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1))
11914 // Otherwise, the other block ended with a conditional branch. If one of the
11915 // destinations is StoreBB, then we have the if/then case.
11916 if (OtherBr->getSuccessor(0) != StoreBB &&
11917 OtherBr->getSuccessor(1) != StoreBB)
11920 // Okay, we know that OtherBr now goes to Dest and StoreBB, so this is an
11921 // if/then triangle. See if there is a store to the same ptr as SI that
11922 // lives in OtherBB.
11924 // Check to see if we find the matching store.
11925 if ((OtherStore = dyn_cast<StoreInst>(BBI))) {
11926 if (OtherStore->getOperand(1) != SI.getOperand(1))
11930 // If we find something that may be using or overwriting the stored
11931 // value, or if we run out of instructions, we can't do the xform.
11932 if (BBI->mayReadFromMemory() || BBI->mayWriteToMemory() ||
11933 BBI == OtherBB->begin())
11937 // In order to eliminate the store in OtherBr, we have to
11938 // make sure nothing reads or overwrites the stored value in
11940 for (BasicBlock::iterator I = StoreBB->begin(); &*I != &SI; ++I) {
11941 // FIXME: This should really be AA driven.
11942 if (I->mayReadFromMemory() || I->mayWriteToMemory())
11947 // Insert a PHI node now if we need it.
11948 Value *MergedVal = OtherStore->getOperand(0);
11949 if (MergedVal != SI.getOperand(0)) {
11950 PHINode *PN = PHINode::Create(MergedVal->getType(), "storemerge");
11951 PN->reserveOperandSpace(2);
11952 PN->addIncoming(SI.getOperand(0), SI.getParent());
11953 PN->addIncoming(OtherStore->getOperand(0), OtherBB);
11954 MergedVal = InsertNewInstBefore(PN, DestBB->front());
11957 // Advance to a place where it is safe to insert the new store and
11959 BBI = DestBB->getFirstNonPHI();
11960 InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
11961 OtherStore->isVolatile()), *BBI);
11963 // Nuke the old stores.
11964 EraseInstFromFunction(SI);
11965 EraseInstFromFunction(*OtherStore);
11971 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
11972 // Change br (not X), label True, label False to: br X, label False, True
11974 BasicBlock *TrueDest;
11975 BasicBlock *FalseDest;
11976 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
11977 !isa<Constant>(X)) {
11978 // Swap Destinations and condition...
11979 BI.setCondition(X);
11980 BI.setSuccessor(0, FalseDest);
11981 BI.setSuccessor(1, TrueDest);
11985 // Cannonicalize fcmp_one -> fcmp_oeq
11986 FCmpInst::Predicate FPred; Value *Y;
11987 if (match(&BI, m_Br(m_FCmp(FPred, m_Value(X), m_Value(Y)),
11988 TrueDest, FalseDest)) &&
11989 BI.getCondition()->hasOneUse())
11990 if (FPred == FCmpInst::FCMP_ONE || FPred == FCmpInst::FCMP_OLE ||
11991 FPred == FCmpInst::FCMP_OGE) {
11992 FCmpInst *Cond = cast<FCmpInst>(BI.getCondition());
11993 Cond->setPredicate(FCmpInst::getInversePredicate(FPred));
11995 // Swap Destinations and condition.
11996 BI.setSuccessor(0, FalseDest);
11997 BI.setSuccessor(1, TrueDest);
11998 Worklist.Add(Cond);
12002 // Cannonicalize icmp_ne -> icmp_eq
12003 ICmpInst::Predicate IPred;
12004 if (match(&BI, m_Br(m_ICmp(IPred, m_Value(X), m_Value(Y)),
12005 TrueDest, FalseDest)) &&
12006 BI.getCondition()->hasOneUse())
12007 if (IPred == ICmpInst::ICMP_NE || IPred == ICmpInst::ICMP_ULE ||
12008 IPred == ICmpInst::ICMP_SLE || IPred == ICmpInst::ICMP_UGE ||
12009 IPred == ICmpInst::ICMP_SGE) {
12010 ICmpInst *Cond = cast<ICmpInst>(BI.getCondition());
12011 Cond->setPredicate(ICmpInst::getInversePredicate(IPred));
12012 // Swap Destinations and condition.
12013 BI.setSuccessor(0, FalseDest);
12014 BI.setSuccessor(1, TrueDest);
12015 Worklist.Add(Cond);
12022 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
12023 Value *Cond = SI.getCondition();
12024 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
12025 if (I->getOpcode() == Instruction::Add)
12026 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
12027 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
12028 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
12030 ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
12032 SI.setOperand(0, I->getOperand(0));
12040 Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) {
12041 Value *Agg = EV.getAggregateOperand();
12043 if (!EV.hasIndices())
12044 return ReplaceInstUsesWith(EV, Agg);
12046 if (Constant *C = dyn_cast<Constant>(Agg)) {
12047 if (isa<UndefValue>(C))
12048 return ReplaceInstUsesWith(EV, UndefValue::get(EV.getType()));
12050 if (isa<ConstantAggregateZero>(C))
12051 return ReplaceInstUsesWith(EV, Constant::getNullValue(EV.getType()));
12053 if (isa<ConstantArray>(C) || isa<ConstantStruct>(C)) {
12054 // Extract the element indexed by the first index out of the constant
12055 Value *V = C->getOperand(*EV.idx_begin());
12056 if (EV.getNumIndices() > 1)
12057 // Extract the remaining indices out of the constant indexed by the
12059 return ExtractValueInst::Create(V, EV.idx_begin() + 1, EV.idx_end());
12061 return ReplaceInstUsesWith(EV, V);
12063 return 0; // Can't handle other constants
12065 if (InsertValueInst *IV = dyn_cast<InsertValueInst>(Agg)) {
12066 // We're extracting from an insertvalue instruction, compare the indices
12067 const unsigned *exti, *exte, *insi, *inse;
12068 for (exti = EV.idx_begin(), insi = IV->idx_begin(),
12069 exte = EV.idx_end(), inse = IV->idx_end();
12070 exti != exte && insi != inse;
12072 if (*insi != *exti)
12073 // The insert and extract both reference distinctly different elements.
12074 // This means the extract is not influenced by the insert, and we can
12075 // replace the aggregate operand of the extract with the aggregate
12076 // operand of the insert. i.e., replace
12077 // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
12078 // %E = extractvalue { i32, { i32 } } %I, 0
12080 // %E = extractvalue { i32, { i32 } } %A, 0
12081 return ExtractValueInst::Create(IV->getAggregateOperand(),
12082 EV.idx_begin(), EV.idx_end());
12084 if (exti == exte && insi == inse)
12085 // Both iterators are at the end: Index lists are identical. Replace
12086 // %B = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
12087 // %C = extractvalue { i32, { i32 } } %B, 1, 0
12089 return ReplaceInstUsesWith(EV, IV->getInsertedValueOperand());
12090 if (exti == exte) {
12091 // The extract list is a prefix of the insert list. i.e. replace
12092 // %I = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
12093 // %E = extractvalue { i32, { i32 } } %I, 1
12095 // %X = extractvalue { i32, { i32 } } %A, 1
12096 // %E = insertvalue { i32 } %X, i32 42, 0
12097 // by switching the order of the insert and extract (though the
12098 // insertvalue should be left in, since it may have other uses).
12099 Value *NewEV = Builder->CreateExtractValue(IV->getAggregateOperand(),
12100 EV.idx_begin(), EV.idx_end());
12101 return InsertValueInst::Create(NewEV, IV->getInsertedValueOperand(),
12105 // The insert list is a prefix of the extract list
12106 // We can simply remove the common indices from the extract and make it
12107 // operate on the inserted value instead of the insertvalue result.
12109 // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
12110 // %E = extractvalue { i32, { i32 } } %I, 1, 0
12112 // %E extractvalue { i32 } { i32 42 }, 0
12113 return ExtractValueInst::Create(IV->getInsertedValueOperand(),
12116 // Can't simplify extracts from other values. Note that nested extracts are
12117 // already simplified implicitely by the above (extract ( extract (insert) )
12118 // will be translated into extract ( insert ( extract ) ) first and then just
12119 // the value inserted, if appropriate).
12123 /// CheapToScalarize - Return true if the value is cheaper to scalarize than it
12124 /// is to leave as a vector operation.
12125 static bool CheapToScalarize(Value *V, bool isConstant) {
12126 if (isa<ConstantAggregateZero>(V))
12128 if (ConstantVector *C = dyn_cast<ConstantVector>(V)) {
12129 if (isConstant) return true;
12130 // If all elts are the same, we can extract.
12131 Constant *Op0 = C->getOperand(0);
12132 for (unsigned i = 1; i < C->getNumOperands(); ++i)
12133 if (C->getOperand(i) != Op0)
12137 Instruction *I = dyn_cast<Instruction>(V);
12138 if (!I) return false;
12140 // Insert element gets simplified to the inserted element or is deleted if
12141 // this is constant idx extract element and its a constant idx insertelt.
12142 if (I->getOpcode() == Instruction::InsertElement && isConstant &&
12143 isa<ConstantInt>(I->getOperand(2)))
12145 if (I->getOpcode() == Instruction::Load && I->hasOneUse())
12147 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I))
12148 if (BO->hasOneUse() &&
12149 (CheapToScalarize(BO->getOperand(0), isConstant) ||
12150 CheapToScalarize(BO->getOperand(1), isConstant)))
12152 if (CmpInst *CI = dyn_cast<CmpInst>(I))
12153 if (CI->hasOneUse() &&
12154 (CheapToScalarize(CI->getOperand(0), isConstant) ||
12155 CheapToScalarize(CI->getOperand(1), isConstant)))
12161 /// Read and decode a shufflevector mask.
12163 /// It turns undef elements into values that are larger than the number of
12164 /// elements in the input.
12165 static std::vector<unsigned> getShuffleMask(const ShuffleVectorInst *SVI) {
12166 unsigned NElts = SVI->getType()->getNumElements();
12167 if (isa<ConstantAggregateZero>(SVI->getOperand(2)))
12168 return std::vector<unsigned>(NElts, 0);
12169 if (isa<UndefValue>(SVI->getOperand(2)))
12170 return std::vector<unsigned>(NElts, 2*NElts);
12172 std::vector<unsigned> Result;
12173 const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2));
12174 for (User::const_op_iterator i = CP->op_begin(), e = CP->op_end(); i!=e; ++i)
12175 if (isa<UndefValue>(*i))
12176 Result.push_back(NElts*2); // undef -> 8
12178 Result.push_back(cast<ConstantInt>(*i)->getZExtValue());
12182 /// FindScalarElement - Given a vector and an element number, see if the scalar
12183 /// value is already around as a register, for example if it were inserted then
12184 /// extracted from the vector.
12185 static Value *FindScalarElement(Value *V, unsigned EltNo,
12186 LLVMContext *Context) {
12187 assert(isa<VectorType>(V->getType()) && "Not looking at a vector?");
12188 const VectorType *PTy = cast<VectorType>(V->getType());
12189 unsigned Width = PTy->getNumElements();
12190 if (EltNo >= Width) // Out of range access.
12191 return UndefValue::get(PTy->getElementType());
12193 if (isa<UndefValue>(V))
12194 return UndefValue::get(PTy->getElementType());
12195 else if (isa<ConstantAggregateZero>(V))
12196 return Constant::getNullValue(PTy->getElementType());
12197 else if (ConstantVector *CP = dyn_cast<ConstantVector>(V))
12198 return CP->getOperand(EltNo);
12199 else if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
12200 // If this is an insert to a variable element, we don't know what it is.
12201 if (!isa<ConstantInt>(III->getOperand(2)))
12203 unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
12205 // If this is an insert to the element we are looking for, return the
12207 if (EltNo == IIElt)
12208 return III->getOperand(1);
12210 // Otherwise, the insertelement doesn't modify the value, recurse on its
12212 return FindScalarElement(III->getOperand(0), EltNo, Context);
12213 } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
12214 unsigned LHSWidth =
12215 cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
12216 unsigned InEl = getShuffleMask(SVI)[EltNo];
12217 if (InEl < LHSWidth)
12218 return FindScalarElement(SVI->getOperand(0), InEl, Context);
12219 else if (InEl < LHSWidth*2)
12220 return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth, Context);
12222 return UndefValue::get(PTy->getElementType());
12225 // Otherwise, we don't know.
12229 Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
12230 // If vector val is undef, replace extract with scalar undef.
12231 if (isa<UndefValue>(EI.getOperand(0)))
12232 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
12234 // If vector val is constant 0, replace extract with scalar 0.
12235 if (isa<ConstantAggregateZero>(EI.getOperand(0)))
12236 return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType()));
12238 if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) {
12239 // If vector val is constant with all elements the same, replace EI with
12240 // that element. When the elements are not identical, we cannot replace yet
12241 // (we do that below, but only when the index is constant).
12242 Constant *op0 = C->getOperand(0);
12243 for (unsigned i = 1; i != C->getNumOperands(); ++i)
12244 if (C->getOperand(i) != op0) {
12249 return ReplaceInstUsesWith(EI, op0);
12252 // If extracting a specified index from the vector, see if we can recursively
12253 // find a previously computed scalar that was inserted into the vector.
12254 if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) {
12255 unsigned IndexVal = IdxC->getZExtValue();
12256 unsigned VectorWidth = EI.getVectorOperandType()->getNumElements();
12258 // If this is extracting an invalid index, turn this into undef, to avoid
12259 // crashing the code below.
12260 if (IndexVal >= VectorWidth)
12261 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
12263 // This instruction only demands the single element from the input vector.
12264 // If the input vector has a single use, simplify it based on this use
12266 if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) {
12267 APInt UndefElts(VectorWidth, 0);
12268 APInt DemandedMask(VectorWidth, 1 << IndexVal);
12269 if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0),
12270 DemandedMask, UndefElts)) {
12271 EI.setOperand(0, V);
12276 if (Value *Elt = FindScalarElement(EI.getOperand(0), IndexVal, Context))
12277 return ReplaceInstUsesWith(EI, Elt);
12279 // If the this extractelement is directly using a bitcast from a vector of
12280 // the same number of elements, see if we can find the source element from
12281 // it. In this case, we will end up needing to bitcast the scalars.
12282 if (BitCastInst *BCI = dyn_cast<BitCastInst>(EI.getOperand(0))) {
12283 if (const VectorType *VT =
12284 dyn_cast<VectorType>(BCI->getOperand(0)->getType()))
12285 if (VT->getNumElements() == VectorWidth)
12286 if (Value *Elt = FindScalarElement(BCI->getOperand(0),
12287 IndexVal, Context))
12288 return new BitCastInst(Elt, EI.getType());
12292 if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) {
12293 // Push extractelement into predecessor operation if legal and
12294 // profitable to do so
12295 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
12296 if (I->hasOneUse() &&
12297 CheapToScalarize(BO, isa<ConstantInt>(EI.getOperand(1)))) {
12299 Builder->CreateExtractElement(BO->getOperand(0), EI.getOperand(1),
12300 EI.getName()+".lhs");
12302 Builder->CreateExtractElement(BO->getOperand(1), EI.getOperand(1),
12303 EI.getName()+".rhs");
12304 return BinaryOperator::Create(BO->getOpcode(), newEI0, newEI1);
12306 } else if (InsertElementInst *IE = dyn_cast<InsertElementInst>(I)) {
12307 // Extracting the inserted element?
12308 if (IE->getOperand(2) == EI.getOperand(1))
12309 return ReplaceInstUsesWith(EI, IE->getOperand(1));
12310 // If the inserted and extracted elements are constants, they must not
12311 // be the same value, extract from the pre-inserted value instead.
12312 if (isa<Constant>(IE->getOperand(2)) && isa<Constant>(EI.getOperand(1))) {
12313 Worklist.AddValue(EI.getOperand(0));
12314 EI.setOperand(0, IE->getOperand(0));
12317 } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I)) {
12318 // If this is extracting an element from a shufflevector, figure out where
12319 // it came from and extract from the appropriate input element instead.
12320 if (ConstantInt *Elt = dyn_cast<ConstantInt>(EI.getOperand(1))) {
12321 unsigned SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()];
12323 unsigned LHSWidth =
12324 cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
12326 if (SrcIdx < LHSWidth)
12327 Src = SVI->getOperand(0);
12328 else if (SrcIdx < LHSWidth*2) {
12329 SrcIdx -= LHSWidth;
12330 Src = SVI->getOperand(1);
12332 return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
12334 return ExtractElementInst::Create(Src,
12335 ConstantInt::get(Type::getInt32Ty(*Context), SrcIdx,
12339 // FIXME: Canonicalize extractelement(bitcast) -> bitcast(extractelement)
12344 /// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
12345 /// elements from either LHS or RHS, return the shuffle mask and true.
12346 /// Otherwise, return false.
12347 static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
12348 std::vector<Constant*> &Mask,
12349 LLVMContext *Context) {
12350 assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
12351 "Invalid CollectSingleShuffleElements");
12352 unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
12354 if (isa<UndefValue>(V)) {
12355 Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(*Context)));
12357 } else if (V == LHS) {
12358 for (unsigned i = 0; i != NumElts; ++i)
12359 Mask.push_back(ConstantInt::get(Type::getInt32Ty(*Context), i));
12361 } else if (V == RHS) {
12362 for (unsigned i = 0; i != NumElts; ++i)
12363 Mask.push_back(ConstantInt::get(Type::getInt32Ty(*Context), i+NumElts));
12365 } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
12366 // If this is an insert of an extract from some other vector, include it.
12367 Value *VecOp = IEI->getOperand(0);
12368 Value *ScalarOp = IEI->getOperand(1);
12369 Value *IdxOp = IEI->getOperand(2);
12371 if (!isa<ConstantInt>(IdxOp))
12373 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
12375 if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector.
12376 // Okay, we can handle this if the vector we are insertinting into is
12377 // transitively ok.
12378 if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask, Context)) {
12379 // If so, update the mask to reflect the inserted undef.
12380 Mask[InsertedIdx] = UndefValue::get(Type::getInt32Ty(*Context));
12383 } else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
12384 if (isa<ConstantInt>(EI->getOperand(1)) &&
12385 EI->getOperand(0)->getType() == V->getType()) {
12386 unsigned ExtractedIdx =
12387 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
12389 // This must be extracting from either LHS or RHS.
12390 if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
12391 // Okay, we can handle this if the vector we are insertinting into is
12392 // transitively ok.
12393 if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask, Context)) {
12394 // If so, update the mask to reflect the inserted value.
12395 if (EI->getOperand(0) == LHS) {
12396 Mask[InsertedIdx % NumElts] =
12397 ConstantInt::get(Type::getInt32Ty(*Context), ExtractedIdx);
12399 assert(EI->getOperand(0) == RHS);
12400 Mask[InsertedIdx % NumElts] =
12401 ConstantInt::get(Type::getInt32Ty(*Context), ExtractedIdx+NumElts);
12410 // TODO: Handle shufflevector here!
12415 /// CollectShuffleElements - We are building a shuffle of V, using RHS as the
12416 /// RHS of the shuffle instruction, if it is not null. Return a shuffle mask
12417 /// that computes V and the LHS value of the shuffle.
12418 static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
12419 Value *&RHS, LLVMContext *Context) {
12420 assert(isa<VectorType>(V->getType()) &&
12421 (RHS == 0 || V->getType() == RHS->getType()) &&
12422 "Invalid shuffle!");
12423 unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
12425 if (isa<UndefValue>(V)) {
12426 Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(*Context)));
12428 } else if (isa<ConstantAggregateZero>(V)) {
12429 Mask.assign(NumElts, ConstantInt::get(Type::getInt32Ty(*Context), 0));
12431 } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
12432 // If this is an insert of an extract from some other vector, include it.
12433 Value *VecOp = IEI->getOperand(0);
12434 Value *ScalarOp = IEI->getOperand(1);
12435 Value *IdxOp = IEI->getOperand(2);
12437 if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
12438 if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
12439 EI->getOperand(0)->getType() == V->getType()) {
12440 unsigned ExtractedIdx =
12441 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
12442 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
12444 // Either the extracted from or inserted into vector must be RHSVec,
12445 // otherwise we'd end up with a shuffle of three inputs.
12446 if (EI->getOperand(0) == RHS || RHS == 0) {
12447 RHS = EI->getOperand(0);
12448 Value *V = CollectShuffleElements(VecOp, Mask, RHS, Context);
12449 Mask[InsertedIdx % NumElts] =
12450 ConstantInt::get(Type::getInt32Ty(*Context), NumElts+ExtractedIdx);
12454 if (VecOp == RHS) {
12455 Value *V = CollectShuffleElements(EI->getOperand(0), Mask,
12457 // Everything but the extracted element is replaced with the RHS.
12458 for (unsigned i = 0; i != NumElts; ++i) {
12459 if (i != InsertedIdx)
12460 Mask[i] = ConstantInt::get(Type::getInt32Ty(*Context), NumElts+i);
12465 // If this insertelement is a chain that comes from exactly these two
12466 // vectors, return the vector and the effective shuffle.
12467 if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask,
12469 return EI->getOperand(0);
12474 // TODO: Handle shufflevector here!
12476 // Otherwise, can't do anything fancy. Return an identity vector.
12477 for (unsigned i = 0; i != NumElts; ++i)
12478 Mask.push_back(ConstantInt::get(Type::getInt32Ty(*Context), i));
12482 Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
12483 Value *VecOp = IE.getOperand(0);
12484 Value *ScalarOp = IE.getOperand(1);
12485 Value *IdxOp = IE.getOperand(2);
12487 // Inserting an undef or into an undefined place, remove this.
12488 if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
12489 ReplaceInstUsesWith(IE, VecOp);
12491 // If the inserted element was extracted from some other vector, and if the
12492 // indexes are constant, try to turn this into a shufflevector operation.
12493 if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
12494 if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
12495 EI->getOperand(0)->getType() == IE.getType()) {
12496 unsigned NumVectorElts = IE.getType()->getNumElements();
12497 unsigned ExtractedIdx =
12498 cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
12499 unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
12501 if (ExtractedIdx >= NumVectorElts) // Out of range extract.
12502 return ReplaceInstUsesWith(IE, VecOp);
12504 if (InsertedIdx >= NumVectorElts) // Out of range insert.
12505 return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType()));
12507 // If we are extracting a value from a vector, then inserting it right
12508 // back into the same place, just use the input vector.
12509 if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
12510 return ReplaceInstUsesWith(IE, VecOp);
12512 // If this insertelement isn't used by some other insertelement, turn it
12513 // (and any insertelements it points to), into one big shuffle.
12514 if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
12515 std::vector<Constant*> Mask;
12517 Value *LHS = CollectShuffleElements(&IE, Mask, RHS, Context);
12518 if (RHS == 0) RHS = UndefValue::get(LHS->getType());
12519 // We now have a shuffle of LHS, RHS, Mask.
12520 return new ShuffleVectorInst(LHS, RHS,
12521 ConstantVector::get(Mask));
12526 unsigned VWidth = cast<VectorType>(VecOp->getType())->getNumElements();
12527 APInt UndefElts(VWidth, 0);
12528 APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
12529 if (SimplifyDemandedVectorElts(&IE, AllOnesEltMask, UndefElts))
12536 Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
12537 Value *LHS = SVI.getOperand(0);
12538 Value *RHS = SVI.getOperand(1);
12539 std::vector<unsigned> Mask = getShuffleMask(&SVI);
12541 bool MadeChange = false;
12543 // Undefined shuffle mask -> undefined value.
12544 if (isa<UndefValue>(SVI.getOperand(2)))
12545 return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
12547 unsigned VWidth = cast<VectorType>(SVI.getType())->getNumElements();
12549 if (VWidth != cast<VectorType>(LHS->getType())->getNumElements())
12552 APInt UndefElts(VWidth, 0);
12553 APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
12554 if (SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts)) {
12555 LHS = SVI.getOperand(0);
12556 RHS = SVI.getOperand(1);
12560 // Canonicalize shuffle(x ,x,mask) -> shuffle(x, undef,mask')
12561 // Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
12562 if (LHS == RHS || isa<UndefValue>(LHS)) {
12563 if (isa<UndefValue>(LHS) && LHS == RHS) {
12564 // shuffle(undef,undef,mask) -> undef.
12565 return ReplaceInstUsesWith(SVI, LHS);
12568 // Remap any references to RHS to use LHS.
12569 std::vector<Constant*> Elts;
12570 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
12571 if (Mask[i] >= 2*e)
12572 Elts.push_back(UndefValue::get(Type::getInt32Ty(*Context)));
12574 if ((Mask[i] >= e && isa<UndefValue>(RHS)) ||
12575 (Mask[i] < e && isa<UndefValue>(LHS))) {
12576 Mask[i] = 2*e; // Turn into undef.
12577 Elts.push_back(UndefValue::get(Type::getInt32Ty(*Context)));
12579 Mask[i] = Mask[i] % e; // Force to LHS.
12580 Elts.push_back(ConstantInt::get(Type::getInt32Ty(*Context), Mask[i]));
12584 SVI.setOperand(0, SVI.getOperand(1));
12585 SVI.setOperand(1, UndefValue::get(RHS->getType()));
12586 SVI.setOperand(2, ConstantVector::get(Elts));
12587 LHS = SVI.getOperand(0);
12588 RHS = SVI.getOperand(1);
12592 // Analyze the shuffle, are the LHS or RHS and identity shuffles?
12593 bool isLHSID = true, isRHSID = true;
12595 for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
12596 if (Mask[i] >= e*2) continue; // Ignore undef values.
12597 // Is this an identity shuffle of the LHS value?
12598 isLHSID &= (Mask[i] == i);
12600 // Is this an identity shuffle of the RHS value?
12601 isRHSID &= (Mask[i]-e == i);
12604 // Eliminate identity shuffles.
12605 if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
12606 if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
12608 // If the LHS is a shufflevector itself, see if we can combine it with this
12609 // one without producing an unusual shuffle. Here we are really conservative:
12610 // we are absolutely afraid of producing a shuffle mask not in the input
12611 // program, because the code gen may not be smart enough to turn a merged
12612 // shuffle into two specific shuffles: it may produce worse code. As such,
12613 // we only merge two shuffles if the result is one of the two input shuffle
12614 // masks. In this case, merging the shuffles just removes one instruction,
12615 // which we know is safe. This is good for things like turning:
12616 // (splat(splat)) -> splat.
12617 if (ShuffleVectorInst *LHSSVI = dyn_cast<ShuffleVectorInst>(LHS)) {
12618 if (isa<UndefValue>(RHS)) {
12619 std::vector<unsigned> LHSMask = getShuffleMask(LHSSVI);
12621 std::vector<unsigned> NewMask;
12622 for (unsigned i = 0, e = Mask.size(); i != e; ++i)
12623 if (Mask[i] >= 2*e)
12624 NewMask.push_back(2*e);
12626 NewMask.push_back(LHSMask[Mask[i]]);
12628 // If the result mask is equal to the src shuffle or this shuffle mask, do
12629 // the replacement.
12630 if (NewMask == LHSMask || NewMask == Mask) {
12631 unsigned LHSInNElts =
12632 cast<VectorType>(LHSSVI->getOperand(0)->getType())->getNumElements();
12633 std::vector<Constant*> Elts;
12634 for (unsigned i = 0, e = NewMask.size(); i != e; ++i) {
12635 if (NewMask[i] >= LHSInNElts*2) {
12636 Elts.push_back(UndefValue::get(Type::getInt32Ty(*Context)));
12638 Elts.push_back(ConstantInt::get(Type::getInt32Ty(*Context), NewMask[i]));
12641 return new ShuffleVectorInst(LHSSVI->getOperand(0),
12642 LHSSVI->getOperand(1),
12643 ConstantVector::get(Elts));
12648 return MadeChange ? &SVI : 0;
12654 /// TryToSinkInstruction - Try to move the specified instruction from its
12655 /// current block into the beginning of DestBlock, which can only happen if it's
12656 /// safe to move the instruction past all of the instructions between it and the
12657 /// end of its block.
12658 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
12659 assert(I->hasOneUse() && "Invariants didn't hold!");
12661 // Cannot move control-flow-involving, volatile loads, vaarg, etc.
12662 if (isa<PHINode>(I) || I->mayHaveSideEffects() || isa<TerminatorInst>(I))
12665 // Do not sink alloca instructions out of the entry block.
12666 if (isa<AllocaInst>(I) && I->getParent() ==
12667 &DestBlock->getParent()->getEntryBlock())
12670 // We can only sink load instructions if there is nothing between the load and
12671 // the end of block that could change the value.
12672 if (I->mayReadFromMemory()) {
12673 for (BasicBlock::iterator Scan = I, E = I->getParent()->end();
12675 if (Scan->mayWriteToMemory())
12679 BasicBlock::iterator InsertPos = DestBlock->getFirstNonPHI();
12681 CopyPrecedingStopPoint(I, InsertPos);
12682 I->moveBefore(InsertPos);
12688 /// AddReachableCodeToWorklist - Walk the function in depth-first order, adding
12689 /// all reachable code to the worklist.
12691 /// This has a couple of tricks to make the code faster and more powerful. In
12692 /// particular, we constant fold and DCE instructions as we go, to avoid adding
12693 /// them to the worklist (this significantly speeds up instcombine on code where
12694 /// many instructions are dead or constant). Additionally, if we find a branch
12695 /// whose condition is a known constant, we only visit the reachable successors.
12697 static bool AddReachableCodeToWorklist(BasicBlock *BB,
12698 SmallPtrSet<BasicBlock*, 64> &Visited,
12700 const TargetData *TD) {
12701 bool MadeIRChange = false;
12702 SmallVector<BasicBlock*, 256> Worklist;
12703 Worklist.push_back(BB);
12705 std::vector<Instruction*> InstrsForInstCombineWorklist;
12706 InstrsForInstCombineWorklist.reserve(128);
12708 SmallPtrSet<ConstantExpr*, 64> FoldedConstants;
12710 while (!Worklist.empty()) {
12711 BB = Worklist.back();
12712 Worklist.pop_back();
12714 // We have now visited this block! If we've already been here, ignore it.
12715 if (!Visited.insert(BB)) continue;
12717 for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
12718 Instruction *Inst = BBI++;
12720 // DCE instruction if trivially dead.
12721 if (isInstructionTriviallyDead(Inst)) {
12723 DEBUG(errs() << "IC: DCE: " << *Inst << '\n');
12724 Inst->eraseFromParent();
12728 // ConstantProp instruction if trivially constant.
12729 if (!Inst->use_empty() && isa<Constant>(Inst->getOperand(0)))
12730 if (Constant *C = ConstantFoldInstruction(Inst, BB->getContext(), TD)) {
12731 DEBUG(errs() << "IC: ConstFold to: " << *C << " from: "
12733 Inst->replaceAllUsesWith(C);
12735 Inst->eraseFromParent();
12742 // See if we can constant fold its operands.
12743 for (User::op_iterator i = Inst->op_begin(), e = Inst->op_end();
12745 ConstantExpr *CE = dyn_cast<ConstantExpr>(i);
12746 if (CE == 0) continue;
12748 // If we already folded this constant, don't try again.
12749 if (!FoldedConstants.insert(CE))
12753 ConstantFoldConstantExpression(CE, BB->getContext(), TD);
12754 if (NewC && NewC != CE) {
12756 MadeIRChange = true;
12762 InstrsForInstCombineWorklist.push_back(Inst);
12765 // Recursively visit successors. If this is a branch or switch on a
12766 // constant, only visit the reachable successor.
12767 TerminatorInst *TI = BB->getTerminator();
12768 if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
12769 if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) {
12770 bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue();
12771 BasicBlock *ReachableBB = BI->getSuccessor(!CondVal);
12772 Worklist.push_back(ReachableBB);
12775 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
12776 if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
12777 // See if this is an explicit destination.
12778 for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i)
12779 if (SI->getCaseValue(i) == Cond) {
12780 BasicBlock *ReachableBB = SI->getSuccessor(i);
12781 Worklist.push_back(ReachableBB);
12785 // Otherwise it is the default destination.
12786 Worklist.push_back(SI->getSuccessor(0));
12791 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
12792 Worklist.push_back(TI->getSuccessor(i));
12795 // Once we've found all of the instructions to add to instcombine's worklist,
12796 // add them in reverse order. This way instcombine will visit from the top
12797 // of the function down. This jives well with the way that it adds all uses
12798 // of instructions to the worklist after doing a transformation, thus avoiding
12799 // some N^2 behavior in pathological cases.
12800 IC.Worklist.AddInitialGroup(&InstrsForInstCombineWorklist[0],
12801 InstrsForInstCombineWorklist.size());
12803 return MadeIRChange;
12806 bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
12807 MadeIRChange = false;
12809 DEBUG(errs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
12810 << F.getNameStr() << "\n");
12813 // Do a depth-first traversal of the function, populate the worklist with
12814 // the reachable instructions. Ignore blocks that are not reachable. Keep
12815 // track of which blocks we visit.
12816 SmallPtrSet<BasicBlock*, 64> Visited;
12817 MadeIRChange |= AddReachableCodeToWorklist(F.begin(), Visited, *this, TD);
12819 // Do a quick scan over the function. If we find any blocks that are
12820 // unreachable, remove any instructions inside of them. This prevents
12821 // the instcombine code from having to deal with some bad special cases.
12822 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
12823 if (!Visited.count(BB)) {
12824 Instruction *Term = BB->getTerminator();
12825 while (Term != BB->begin()) { // Remove instrs bottom-up
12826 BasicBlock::iterator I = Term; --I;
12828 DEBUG(errs() << "IC: DCE: " << *I << '\n');
12829 // A debug intrinsic shouldn't force another iteration if we weren't
12830 // going to do one without it.
12831 if (!isa<DbgInfoIntrinsic>(I)) {
12833 MadeIRChange = true;
12836 // If I is not void type then replaceAllUsesWith undef.
12837 // This allows ValueHandlers and custom metadata to adjust itself.
12838 if (!I->getType()->isVoidTy())
12839 I->replaceAllUsesWith(UndefValue::get(I->getType()));
12840 I->eraseFromParent();
12845 while (!Worklist.isEmpty()) {
12846 Instruction *I = Worklist.RemoveOne();
12847 if (I == 0) continue; // skip null values.
12849 // Check to see if we can DCE the instruction.
12850 if (isInstructionTriviallyDead(I)) {
12851 DEBUG(errs() << "IC: DCE: " << *I << '\n');
12852 EraseInstFromFunction(*I);
12854 MadeIRChange = true;
12858 // Instruction isn't dead, see if we can constant propagate it.
12859 if (!I->use_empty() && isa<Constant>(I->getOperand(0)))
12860 if (Constant *C = ConstantFoldInstruction(I, F.getContext(), TD)) {
12861 DEBUG(errs() << "IC: ConstFold to: " << *C << " from: " << *I << '\n');
12863 // Add operands to the worklist.
12864 ReplaceInstUsesWith(*I, C);
12866 EraseInstFromFunction(*I);
12867 MadeIRChange = true;
12871 // See if we can trivially sink this instruction to a successor basic block.
12872 if (I->hasOneUse()) {
12873 BasicBlock *BB = I->getParent();
12874 Instruction *UserInst = cast<Instruction>(I->use_back());
12875 BasicBlock *UserParent;
12877 // Get the block the use occurs in.
12878 if (PHINode *PN = dyn_cast<PHINode>(UserInst))
12879 UserParent = PN->getIncomingBlock(I->use_begin().getUse());
12881 UserParent = UserInst->getParent();
12883 if (UserParent != BB) {
12884 bool UserIsSuccessor = false;
12885 // See if the user is one of our successors.
12886 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
12887 if (*SI == UserParent) {
12888 UserIsSuccessor = true;
12892 // If the user is one of our immediate successors, and if that successor
12893 // only has us as a predecessors (we'd have to split the critical edge
12894 // otherwise), we can keep going.
12895 if (UserIsSuccessor && UserParent->getSinglePredecessor())
12896 // Okay, the CFG is simple enough, try to sink this instruction.
12897 MadeIRChange |= TryToSinkInstruction(I, UserParent);
12901 // Now that we have an instruction, try combining it to simplify it.
12902 Builder->SetInsertPoint(I->getParent(), I);
12907 DEBUG(raw_string_ostream SS(OrigI); I->print(SS); OrigI = SS.str(););
12908 DEBUG(errs() << "IC: Visiting: " << OrigI << '\n');
12910 if (Instruction *Result = visit(*I)) {
12912 // Should we replace the old instruction with a new one?
12914 DEBUG(errs() << "IC: Old = " << *I << '\n'
12915 << " New = " << *Result << '\n');
12917 // Everything uses the new instruction now.
12918 I->replaceAllUsesWith(Result);
12920 // Push the new instruction and any users onto the worklist.
12921 Worklist.Add(Result);
12922 Worklist.AddUsersToWorkList(*Result);
12924 // Move the name to the new instruction first.
12925 Result->takeName(I);
12927 // Insert the new instruction into the basic block...
12928 BasicBlock *InstParent = I->getParent();
12929 BasicBlock::iterator InsertPos = I;
12931 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
12932 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
12935 InstParent->getInstList().insert(InsertPos, Result);
12937 EraseInstFromFunction(*I);
12940 DEBUG(errs() << "IC: Mod = " << OrigI << '\n'
12941 << " New = " << *I << '\n');
12944 // If the instruction was modified, it's possible that it is now dead.
12945 // if so, remove it.
12946 if (isInstructionTriviallyDead(I)) {
12947 EraseInstFromFunction(*I);
12950 Worklist.AddUsersToWorkList(*I);
12953 MadeIRChange = true;
12958 return MadeIRChange;
12962 bool InstCombiner::runOnFunction(Function &F) {
12963 MustPreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
12964 Context = &F.getContext();
12965 TD = getAnalysisIfAvailable<TargetData>();
12968 /// Builder - This is an IRBuilder that automatically inserts new
12969 /// instructions into the worklist when they are created.
12970 IRBuilder<true, TargetFolder, InstCombineIRInserter>
12971 TheBuilder(F.getContext(), TargetFolder(TD, F.getContext()),
12972 InstCombineIRInserter(Worklist));
12973 Builder = &TheBuilder;
12975 bool EverMadeChange = false;
12977 // Iterate while there is work to do.
12978 unsigned Iteration = 0;
12979 while (DoOneIteration(F, Iteration++))
12980 EverMadeChange = true;
12983 return EverMadeChange;
12986 FunctionPass *llvm::createInstructionCombiningPass() {
12987 return new InstCombiner();