1 //===- InstructionCombining.cpp - Combine multiple instructions -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source 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 algebraic
12 // 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. SetCC instructions are converted from <,>,<=,>= to ==,!= if possible
28 // 4. All SetCC 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/Pass.h"
40 #include "llvm/DerivedTypes.h"
41 #include "llvm/GlobalVariable.h"
42 #include "llvm/Target/TargetData.h"
43 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
44 #include "llvm/Transforms/Utils/Local.h"
45 #include "llvm/Support/CallSite.h"
46 #include "llvm/Support/Debug.h"
47 #include "llvm/Support/GetElementPtrTypeIterator.h"
48 #include "llvm/Support/InstIterator.h"
49 #include "llvm/Support/InstVisitor.h"
50 #include "llvm/Support/PatternMatch.h"
51 #include "llvm/ADT/Statistic.h"
52 #include "llvm/ADT/STLExtras.h"
55 using namespace llvm::PatternMatch;
58 Statistic<> NumCombined ("instcombine", "Number of insts combined");
59 Statistic<> NumConstProp("instcombine", "Number of constant folds");
60 Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
61 Statistic<> NumSunkInst ("instcombine", "Number of instructions sunk");
63 class InstCombiner : public FunctionPass,
64 public InstVisitor<InstCombiner, Instruction*> {
65 // Worklist of all of the instructions that need to be simplified.
66 std::vector<Instruction*> WorkList;
69 /// AddUsersToWorkList - When an instruction is simplified, add all users of
70 /// the instruction to the work lists because they might get more simplified
73 void AddUsersToWorkList(Instruction &I) {
74 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
76 WorkList.push_back(cast<Instruction>(*UI));
79 /// AddUsesToWorkList - When an instruction is simplified, add operands to
80 /// the work lists because they might get more simplified now.
82 void AddUsesToWorkList(Instruction &I) {
83 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
84 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
85 WorkList.push_back(Op);
88 // removeFromWorkList - remove all instances of I from the worklist.
89 void removeFromWorkList(Instruction *I);
91 virtual bool runOnFunction(Function &F);
93 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
94 AU.addRequired<TargetData>();
98 TargetData &getTargetData() const { return *TD; }
100 // Visitation implementation - Implement instruction combining for different
101 // instruction types. The semantics are as follows:
103 // null - No change was made
104 // I - Change was made, I is still valid, I may be dead though
105 // otherwise - Change was made, replace I with returned instruction
107 Instruction *visitAdd(BinaryOperator &I);
108 Instruction *visitSub(BinaryOperator &I);
109 Instruction *visitMul(BinaryOperator &I);
110 Instruction *visitDiv(BinaryOperator &I);
111 Instruction *visitRem(BinaryOperator &I);
112 Instruction *visitAnd(BinaryOperator &I);
113 Instruction *visitOr (BinaryOperator &I);
114 Instruction *visitXor(BinaryOperator &I);
115 Instruction *visitSetCondInst(BinaryOperator &I);
116 Instruction *visitSetCondInstWithCastAndConstant(BinaryOperator&I,
119 Instruction *FoldGEPSetCC(User *GEPLHS, Value *RHS,
120 Instruction::BinaryOps Cond, Instruction &I);
121 Instruction *visitShiftInst(ShiftInst &I);
122 Instruction *visitCastInst(CastInst &CI);
123 Instruction *visitSelectInst(SelectInst &CI);
124 Instruction *visitCallInst(CallInst &CI);
125 Instruction *visitInvokeInst(InvokeInst &II);
126 Instruction *visitPHINode(PHINode &PN);
127 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
128 Instruction *visitAllocationInst(AllocationInst &AI);
129 Instruction *visitFreeInst(FreeInst &FI);
130 Instruction *visitLoadInst(LoadInst &LI);
131 Instruction *visitBranchInst(BranchInst &BI);
132 Instruction *visitSwitchInst(SwitchInst &SI);
134 // visitInstruction - Specify what to return for unhandled instructions...
135 Instruction *visitInstruction(Instruction &I) { return 0; }
138 Instruction *visitCallSite(CallSite CS);
139 bool transformConstExprCastCall(CallSite CS);
142 // InsertNewInstBefore - insert an instruction New before instruction Old
143 // in the program. Add the new instruction to the worklist.
145 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
146 assert(New && New->getParent() == 0 &&
147 "New instruction already inserted into a basic block!");
148 BasicBlock *BB = Old.getParent();
149 BB->getInstList().insert(&Old, New); // Insert inst
150 WorkList.push_back(New); // Add to worklist
154 /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
155 /// This also adds the cast to the worklist. Finally, this returns the
157 Value *InsertCastBefore(Value *V, const Type *Ty, Instruction &Pos) {
158 if (V->getType() == Ty) return V;
160 Instruction *C = new CastInst(V, Ty, V->getName(), &Pos);
161 WorkList.push_back(C);
165 // ReplaceInstUsesWith - This method is to be used when an instruction is
166 // found to be dead, replacable with another preexisting expression. Here
167 // we add all uses of I to the worklist, replace all uses of I with the new
168 // value, then return I, so that the inst combiner will know that I was
171 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
172 AddUsersToWorkList(I); // Add all modified instrs to worklist
174 I.replaceAllUsesWith(V);
177 // If we are replacing the instruction with itself, this must be in a
178 // segment of unreachable code, so just clobber the instruction.
179 I.replaceAllUsesWith(UndefValue::get(I.getType()));
184 // EraseInstFromFunction - When dealing with an instruction that has side
185 // effects or produces a void value, we can't rely on DCE to delete the
186 // instruction. Instead, visit methods should return the value returned by
188 Instruction *EraseInstFromFunction(Instruction &I) {
189 assert(I.use_empty() && "Cannot erase instruction that is used!");
190 AddUsesToWorkList(I);
191 removeFromWorkList(&I);
193 return 0; // Don't do anything with FI
198 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
199 /// InsertBefore instruction. This is specialized a bit to avoid inserting
200 /// casts that are known to not do anything...
202 Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
203 Instruction *InsertBefore);
205 // SimplifyCommutative - This performs a few simplifications for commutative
207 bool SimplifyCommutative(BinaryOperator &I);
210 // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
211 // PHI node as operand #0, see if we can fold the instruction into the PHI
212 // (which is only possible if all operands to the PHI are constants).
213 Instruction *FoldOpIntoPhi(Instruction &I);
215 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
216 // operator and they all are only used by the PHI, PHI together their
217 // inputs, and do the operation once, to the result of the PHI.
218 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
220 Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
221 ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
223 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
224 bool Inside, Instruction &IB);
227 RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
230 // getComplexity: Assign a complexity or rank value to LLVM Values...
231 // 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
232 static unsigned getComplexity(Value *V) {
233 if (isa<Instruction>(V)) {
234 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
238 if (isa<Argument>(V)) return 3;
239 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
242 // isOnlyUse - Return true if this instruction will be deleted if we stop using
244 static bool isOnlyUse(Value *V) {
245 return V->hasOneUse() || isa<Constant>(V);
248 // getPromotedType - Return the specified type promoted as it would be to pass
249 // though a va_arg area...
250 static const Type *getPromotedType(const Type *Ty) {
251 switch (Ty->getTypeID()) {
252 case Type::SByteTyID:
253 case Type::ShortTyID: return Type::IntTy;
254 case Type::UByteTyID:
255 case Type::UShortTyID: return Type::UIntTy;
256 case Type::FloatTyID: return Type::DoubleTy;
261 // SimplifyCommutative - This performs a few simplifications for commutative
264 // 1. Order operands such that they are listed from right (least complex) to
265 // left (most complex). This puts constants before unary operators before
268 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
269 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
271 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
272 bool Changed = false;
273 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
274 Changed = !I.swapOperands();
276 if (!I.isAssociative()) return Changed;
277 Instruction::BinaryOps Opcode = I.getOpcode();
278 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
279 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
280 if (isa<Constant>(I.getOperand(1))) {
281 Constant *Folded = ConstantExpr::get(I.getOpcode(),
282 cast<Constant>(I.getOperand(1)),
283 cast<Constant>(Op->getOperand(1)));
284 I.setOperand(0, Op->getOperand(0));
285 I.setOperand(1, Folded);
287 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
288 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
289 isOnlyUse(Op) && isOnlyUse(Op1)) {
290 Constant *C1 = cast<Constant>(Op->getOperand(1));
291 Constant *C2 = cast<Constant>(Op1->getOperand(1));
293 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
294 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
295 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
298 WorkList.push_back(New);
299 I.setOperand(0, New);
300 I.setOperand(1, Folded);
307 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
308 // if the LHS is a constant zero (which is the 'negate' form).
310 static inline Value *dyn_castNegVal(Value *V) {
311 if (BinaryOperator::isNeg(V))
312 return BinaryOperator::getNegArgument(cast<BinaryOperator>(V));
314 // Constants can be considered to be negated values if they can be folded.
315 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
316 return ConstantExpr::getNeg(C);
320 static inline Value *dyn_castNotVal(Value *V) {
321 if (BinaryOperator::isNot(V))
322 return BinaryOperator::getNotArgument(cast<BinaryOperator>(V));
324 // Constants can be considered to be not'ed values...
325 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
326 return ConstantExpr::getNot(C);
330 // dyn_castFoldableMul - If this value is a multiply that can be folded into
331 // other computations (because it has a constant operand), return the
332 // non-constant operand of the multiply, and set CST to point to the multiplier.
333 // Otherwise, return null.
335 static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
336 if (V->hasOneUse() && V->getType()->isInteger())
337 if (Instruction *I = dyn_cast<Instruction>(V)) {
338 if (I->getOpcode() == Instruction::Mul)
339 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
340 return I->getOperand(0);
341 if (I->getOpcode() == Instruction::Shl)
342 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
343 // The multiplier is really 1 << CST.
344 Constant *One = ConstantInt::get(V->getType(), 1);
345 CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
346 return I->getOperand(0);
352 /// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
353 /// expression, return it.
354 static User *dyn_castGetElementPtr(Value *V) {
355 if (isa<GetElementPtrInst>(V)) return cast<User>(V);
356 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
357 if (CE->getOpcode() == Instruction::GetElementPtr)
358 return cast<User>(V);
362 // Log2 - Calculate the log base 2 for the specified value if it is exactly a
364 static unsigned Log2(uint64_t Val) {
365 assert(Val > 1 && "Values 0 and 1 should be handled elsewhere!");
368 if (Val & 1) return 0; // Multiple bits set?
375 // AddOne, SubOne - Add or subtract a constant one from an integer constant...
376 static ConstantInt *AddOne(ConstantInt *C) {
377 return cast<ConstantInt>(ConstantExpr::getAdd(C,
378 ConstantInt::get(C->getType(), 1)));
380 static ConstantInt *SubOne(ConstantInt *C) {
381 return cast<ConstantInt>(ConstantExpr::getSub(C,
382 ConstantInt::get(C->getType(), 1)));
385 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
386 // true when both operands are equal...
388 static bool isTrueWhenEqual(Instruction &I) {
389 return I.getOpcode() == Instruction::SetEQ ||
390 I.getOpcode() == Instruction::SetGE ||
391 I.getOpcode() == Instruction::SetLE;
394 /// AssociativeOpt - Perform an optimization on an associative operator. This
395 /// function is designed to check a chain of associative operators for a
396 /// potential to apply a certain optimization. Since the optimization may be
397 /// applicable if the expression was reassociated, this checks the chain, then
398 /// reassociates the expression as necessary to expose the optimization
399 /// opportunity. This makes use of a special Functor, which must define
400 /// 'shouldApply' and 'apply' methods.
402 template<typename Functor>
403 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
404 unsigned Opcode = Root.getOpcode();
405 Value *LHS = Root.getOperand(0);
407 // Quick check, see if the immediate LHS matches...
408 if (F.shouldApply(LHS))
409 return F.apply(Root);
411 // Otherwise, if the LHS is not of the same opcode as the root, return.
412 Instruction *LHSI = dyn_cast<Instruction>(LHS);
413 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
414 // Should we apply this transform to the RHS?
415 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
417 // If not to the RHS, check to see if we should apply to the LHS...
418 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
419 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
423 // If the functor wants to apply the optimization to the RHS of LHSI,
424 // reassociate the expression from ((? op A) op B) to (? op (A op B))
426 BasicBlock *BB = Root.getParent();
428 // Now all of the instructions are in the current basic block, go ahead
429 // and perform the reassociation.
430 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
432 // First move the selected RHS to the LHS of the root...
433 Root.setOperand(0, LHSI->getOperand(1));
435 // Make what used to be the LHS of the root be the user of the root...
436 Value *ExtraOperand = TmpLHSI->getOperand(1);
437 if (&Root == TmpLHSI) {
438 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
441 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
442 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
443 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
444 BasicBlock::iterator ARI = &Root; ++ARI;
445 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
448 // Now propagate the ExtraOperand down the chain of instructions until we
450 while (TmpLHSI != LHSI) {
451 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
452 // Move the instruction to immediately before the chain we are
453 // constructing to avoid breaking dominance properties.
454 NextLHSI->getParent()->getInstList().remove(NextLHSI);
455 BB->getInstList().insert(ARI, NextLHSI);
458 Value *NextOp = NextLHSI->getOperand(1);
459 NextLHSI->setOperand(1, ExtraOperand);
461 ExtraOperand = NextOp;
464 // Now that the instructions are reassociated, have the functor perform
465 // the transformation...
466 return F.apply(Root);
469 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
475 // AddRHS - Implements: X + X --> X << 1
478 AddRHS(Value *rhs) : RHS(rhs) {}
479 bool shouldApply(Value *LHS) const { return LHS == RHS; }
480 Instruction *apply(BinaryOperator &Add) const {
481 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
482 ConstantInt::get(Type::UByteTy, 1));
486 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
488 struct AddMaskingAnd {
490 AddMaskingAnd(Constant *c) : C2(c) {}
491 bool shouldApply(Value *LHS) const {
493 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
494 ConstantExpr::getAnd(C1, C2)->isNullValue();
496 Instruction *apply(BinaryOperator &Add) const {
497 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
501 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
503 if (isa<CastInst>(I)) {
504 if (Constant *SOC = dyn_cast<Constant>(SO))
505 return ConstantExpr::getCast(SOC, I.getType());
507 return IC->InsertNewInstBefore(new CastInst(SO, I.getType(),
508 SO->getName() + ".cast"), I);
511 // Figure out if the constant is the left or the right argument.
512 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
513 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
515 if (Constant *SOC = dyn_cast<Constant>(SO)) {
517 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
518 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
521 Value *Op0 = SO, *Op1 = ConstOperand;
525 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
526 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
527 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&I))
528 New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh");
530 assert(0 && "Unknown binary instruction type!");
533 return IC->InsertNewInstBefore(New, I);
536 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
537 // constant as the other operand, try to fold the binary operator into the
538 // select arguments. This also works for Cast instructions, which obviously do
539 // not have a second operand.
540 static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
542 // Don't modify shared select instructions
543 if (!SI->hasOneUse()) return 0;
544 Value *TV = SI->getOperand(1);
545 Value *FV = SI->getOperand(2);
547 if (isa<Constant>(TV) || isa<Constant>(FV)) {
548 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
549 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
551 return new SelectInst(SI->getCondition(), SelectTrueVal,
558 /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
559 /// node as operand #0, see if we can fold the instruction into the PHI (which
560 /// is only possible if all operands to the PHI are constants).
561 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
562 PHINode *PN = cast<PHINode>(I.getOperand(0));
563 unsigned NumPHIValues = PN->getNumIncomingValues();
564 if (!PN->hasOneUse() || NumPHIValues == 0 ||
565 !isa<Constant>(PN->getIncomingValue(0))) return 0;
567 // Check to see if all of the operands of the PHI are constants. If not, we
568 // cannot do the transformation.
569 for (unsigned i = 1; i != NumPHIValues; ++i)
570 if (!isa<Constant>(PN->getIncomingValue(i)))
573 // Okay, we can do the transformation: create the new PHI node.
574 PHINode *NewPN = new PHINode(I.getType(), I.getName());
576 NewPN->op_reserve(PN->getNumOperands());
577 InsertNewInstBefore(NewPN, *PN);
579 // Next, add all of the operands to the PHI.
580 if (I.getNumOperands() == 2) {
581 Constant *C = cast<Constant>(I.getOperand(1));
582 for (unsigned i = 0; i != NumPHIValues; ++i) {
583 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
584 NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
585 PN->getIncomingBlock(i));
588 assert(isa<CastInst>(I) && "Unary op should be a cast!");
589 const Type *RetTy = I.getType();
590 for (unsigned i = 0; i != NumPHIValues; ++i) {
591 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
592 NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
593 PN->getIncomingBlock(i));
596 return ReplaceInstUsesWith(I, NewPN);
599 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
600 bool Changed = SimplifyCommutative(I);
601 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
603 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
604 // X + undef -> undef
605 if (isa<UndefValue>(RHS))
606 return ReplaceInstUsesWith(I, RHS);
609 if (!I.getType()->isFloatingPoint() && // -0 + +0 = +0, so it's not a noop
611 return ReplaceInstUsesWith(I, LHS);
613 // X + (signbit) --> X ^ signbit
614 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
615 unsigned NumBits = CI->getType()->getPrimitiveSize()*8;
616 uint64_t Val = CI->getRawValue() & (1ULL << NumBits)-1;
617 if (Val == (1ULL << (NumBits-1)))
618 return BinaryOperator::createXor(LHS, RHS);
621 if (isa<PHINode>(LHS))
622 if (Instruction *NV = FoldOpIntoPhi(I))
627 if (I.getType()->isInteger()) {
628 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
632 if (Value *V = dyn_castNegVal(LHS))
633 return BinaryOperator::createSub(RHS, V);
636 if (!isa<Constant>(RHS))
637 if (Value *V = dyn_castNegVal(RHS))
638 return BinaryOperator::createSub(LHS, V);
641 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
642 if (X == RHS) // X*C + X --> X * (C+1)
643 return BinaryOperator::createMul(RHS, AddOne(C2));
645 // X*C1 + X*C2 --> X * (C1+C2)
647 if (X == dyn_castFoldableMul(RHS, C1))
648 return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2));
651 // X + X*C --> X * (C+1)
652 if (dyn_castFoldableMul(RHS, C2) == LHS)
653 return BinaryOperator::createMul(LHS, AddOne(C2));
656 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
657 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
658 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
660 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
662 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
663 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
664 return BinaryOperator::createSub(C, X);
667 // (X & FF00) + xx00 -> (X+xx00) & FF00
668 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
669 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
671 // See if all bits from the first bit set in the Add RHS up are included
672 // in the mask. First, get the rightmost bit.
673 uint64_t AddRHSV = CRHS->getRawValue();
675 // Form a mask of all bits from the lowest bit added through the top.
676 uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
677 AddRHSHighBits &= (1ULL << C2->getType()->getPrimitiveSize()*8)-1;
679 // See if the and mask includes all of these bits.
680 uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue();
682 if (AddRHSHighBits == AddRHSHighBitsAnd) {
683 // Okay, the xform is safe. Insert the new add pronto.
684 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
686 return BinaryOperator::createAnd(NewAdd, C2);
691 // Try to fold constant add into select arguments.
692 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
693 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
697 return Changed ? &I : 0;
700 // isSignBit - Return true if the value represented by the constant only has the
701 // highest order bit set.
702 static bool isSignBit(ConstantInt *CI) {
703 unsigned NumBits = CI->getType()->getPrimitiveSize()*8;
704 return (CI->getRawValue() & ~(-1LL << NumBits)) == (1ULL << (NumBits-1));
707 static unsigned getTypeSizeInBits(const Type *Ty) {
708 return Ty == Type::BoolTy ? 1 : Ty->getPrimitiveSize()*8;
711 /// RemoveNoopCast - Strip off nonconverting casts from the value.
713 static Value *RemoveNoopCast(Value *V) {
714 if (CastInst *CI = dyn_cast<CastInst>(V)) {
715 const Type *CTy = CI->getType();
716 const Type *OpTy = CI->getOperand(0)->getType();
717 if (CTy->isInteger() && OpTy->isInteger()) {
718 if (CTy->getPrimitiveSize() == OpTy->getPrimitiveSize())
719 return RemoveNoopCast(CI->getOperand(0));
720 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
721 return RemoveNoopCast(CI->getOperand(0));
726 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
727 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
729 if (Op0 == Op1) // sub X, X -> 0
730 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
732 // If this is a 'B = x-(-A)', change to B = x+A...
733 if (Value *V = dyn_castNegVal(Op1))
734 return BinaryOperator::createAdd(Op0, V);
736 if (isa<UndefValue>(Op0))
737 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
738 if (isa<UndefValue>(Op1))
739 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
741 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
742 // Replace (-1 - A) with (~A)...
743 if (C->isAllOnesValue())
744 return BinaryOperator::createNot(Op1);
746 // C - ~X == X + (1+C)
748 if (match(Op1, m_Not(m_Value(X))))
749 return BinaryOperator::createAdd(X,
750 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
751 // -((uint)X >> 31) -> ((int)X >> 31)
752 // -((int)X >> 31) -> ((uint)X >> 31)
753 if (C->isNullValue()) {
754 Value *NoopCastedRHS = RemoveNoopCast(Op1);
755 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
756 if (SI->getOpcode() == Instruction::Shr)
757 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
759 if (SI->getType()->isSigned())
760 NewTy = SI->getType()->getUnsignedVersion();
762 NewTy = SI->getType()->getSignedVersion();
763 // Check to see if we are shifting out everything but the sign bit.
764 if (CU->getValue() == SI->getType()->getPrimitiveSize()*8-1) {
765 // Ok, the transformation is safe. Insert a cast of the incoming
766 // value, then the new shift, then the new cast.
767 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
768 SI->getOperand(0)->getName());
769 Value *InV = InsertNewInstBefore(FirstCast, I);
770 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
772 if (NewShift->getType() == I.getType())
775 InV = InsertNewInstBefore(NewShift, I);
776 return new CastInst(NewShift, I.getType());
782 // Try to fold constant sub into select arguments.
783 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
784 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
787 if (isa<PHINode>(Op0))
788 if (Instruction *NV = FoldOpIntoPhi(I))
792 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1))
793 if (Op1I->hasOneUse()) {
794 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
795 // is not used by anyone else...
797 if (Op1I->getOpcode() == Instruction::Sub &&
798 !Op1I->getType()->isFloatingPoint()) {
799 // Swap the two operands of the subexpr...
800 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
801 Op1I->setOperand(0, IIOp1);
802 Op1I->setOperand(1, IIOp0);
804 // Create the new top level add instruction...
805 return BinaryOperator::createAdd(Op0, Op1);
808 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
810 if (Op1I->getOpcode() == Instruction::And &&
811 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
812 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
815 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
816 return BinaryOperator::createAnd(Op0, NewNot);
819 // -(X sdiv C) -> (X sdiv -C)
820 if (Op1I->getOpcode() == Instruction::Div)
821 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
822 if (CSI->getValue() == 0)
823 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
824 return BinaryOperator::createDiv(Op1I->getOperand(0),
825 ConstantExpr::getNeg(DivRHS));
827 // X - X*C --> X * (1-C)
829 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
831 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
832 return BinaryOperator::createMul(Op0, CP1);
838 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
839 if (X == Op1) { // X*C - X --> X * (C-1)
840 Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
841 return BinaryOperator::createMul(Op1, CP1);
844 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
845 if (X == dyn_castFoldableMul(Op1, C2))
846 return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
851 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
852 /// really just returns true if the most significant (sign) bit is set.
853 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
854 if (RHS->getType()->isSigned()) {
855 // True if source is LHS < 0 or LHS <= -1
856 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
857 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
859 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
860 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
861 // the size of the integer type.
862 if (Opcode == Instruction::SetGE)
863 return RHSC->getValue() == 1ULL<<(RHS->getType()->getPrimitiveSize()*8-1);
864 if (Opcode == Instruction::SetGT)
865 return RHSC->getValue() ==
866 (1ULL << (RHS->getType()->getPrimitiveSize()*8-1))-1;
871 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
872 bool Changed = SimplifyCommutative(I);
873 Value *Op0 = I.getOperand(0);
875 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
876 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
878 // Simplify mul instructions with a constant RHS...
879 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
880 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
882 // ((X << C1)*C2) == (X * (C2 << C1))
883 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
884 if (SI->getOpcode() == Instruction::Shl)
885 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
886 return BinaryOperator::createMul(SI->getOperand(0),
887 ConstantExpr::getShl(CI, ShOp));
889 if (CI->isNullValue())
890 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
891 if (CI->equalsInt(1)) // X * 1 == X
892 return ReplaceInstUsesWith(I, Op0);
893 if (CI->isAllOnesValue()) // X * -1 == 0 - X
894 return BinaryOperator::createNeg(Op0, I.getName());
896 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
897 if (uint64_t C = Log2(Val)) // Replace X*(2^C) with X << C
898 return new ShiftInst(Instruction::Shl, Op0,
899 ConstantUInt::get(Type::UByteTy, C));
900 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
901 if (Op1F->isNullValue())
902 return ReplaceInstUsesWith(I, Op1);
904 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
905 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
906 if (Op1F->getValue() == 1.0)
907 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
910 // Try to fold constant mul into select arguments.
911 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
912 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
915 if (isa<PHINode>(Op0))
916 if (Instruction *NV = FoldOpIntoPhi(I))
920 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
921 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
922 return BinaryOperator::createMul(Op0v, Op1v);
924 // If one of the operands of the multiply is a cast from a boolean value, then
925 // we know the bool is either zero or one, so this is a 'masking' multiply.
926 // See if we can simplify things based on how the boolean was originally
928 CastInst *BoolCast = 0;
929 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
930 if (CI->getOperand(0)->getType() == Type::BoolTy)
933 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
934 if (CI->getOperand(0)->getType() == Type::BoolTy)
937 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
938 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
939 const Type *SCOpTy = SCIOp0->getType();
941 // If the setcc is true iff the sign bit of X is set, then convert this
942 // multiply into a shift/and combination.
943 if (isa<ConstantInt>(SCIOp1) &&
944 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
945 // Shift the X value right to turn it into "all signbits".
946 Constant *Amt = ConstantUInt::get(Type::UByteTy,
947 SCOpTy->getPrimitiveSize()*8-1);
948 if (SCIOp0->getType()->isUnsigned()) {
949 const Type *NewTy = SCIOp0->getType()->getSignedVersion();
950 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
951 SCIOp0->getName()), I);
955 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
956 BoolCast->getOperand(0)->getName()+
959 // If the multiply type is not the same as the source type, sign extend
960 // or truncate to the multiply type.
961 if (I.getType() != V->getType())
962 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
964 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
965 return BinaryOperator::createAnd(V, OtherOp);
970 return Changed ? &I : 0;
973 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
974 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
976 if (isa<UndefValue>(Op0)) // undef / X -> 0
977 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
978 if (isa<UndefValue>(Op1))
979 return ReplaceInstUsesWith(I, Op1); // X / undef -> undef
981 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
983 if (RHS->equalsInt(1))
984 return ReplaceInstUsesWith(I, Op0);
987 if (RHS->isAllOnesValue())
988 return BinaryOperator::createNeg(Op0);
990 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
991 if (LHS->getOpcode() == Instruction::Div)
992 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
993 // (X / C1) / C2 -> X / (C1*C2)
994 return BinaryOperator::createDiv(LHS->getOperand(0),
995 ConstantExpr::getMul(RHS, LHSRHS));
998 // Check to see if this is an unsigned division with an exact power of 2,
999 // if so, convert to a right shift.
1000 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1001 if (uint64_t Val = C->getValue()) // Don't break X / 0
1002 if (uint64_t C = Log2(Val))
1003 return new ShiftInst(Instruction::Shr, Op0,
1004 ConstantUInt::get(Type::UByteTy, C));
1007 if (RHS->getType()->isSigned())
1008 if (Value *LHSNeg = dyn_castNegVal(Op0))
1009 return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS));
1011 if (!RHS->isNullValue()) {
1012 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1013 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1015 if (isa<PHINode>(Op0))
1016 if (Instruction *NV = FoldOpIntoPhi(I))
1021 // If this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1022 // transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'.
1023 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1024 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1025 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1026 if (STO->getValue() == 0) { // Couldn't be this argument.
1027 I.setOperand(1, SFO);
1029 } else if (SFO->getValue() == 0) {
1030 I.setOperand(1, STO);
1034 if (uint64_t TSA = Log2(STO->getValue()))
1035 if (uint64_t FSA = Log2(SFO->getValue())) {
1036 Constant *TC = ConstantUInt::get(Type::UByteTy, TSA);
1037 Instruction *TSI = new ShiftInst(Instruction::Shr, Op0,
1038 TC, SI->getName()+".t");
1039 TSI = InsertNewInstBefore(TSI, I);
1041 Constant *FC = ConstantUInt::get(Type::UByteTy, FSA);
1042 Instruction *FSI = new ShiftInst(Instruction::Shr, Op0,
1043 FC, SI->getName()+".f");
1044 FSI = InsertNewInstBefore(FSI, I);
1045 return new SelectInst(SI->getOperand(0), TSI, FSI);
1049 // 0 / X == 0, we don't need to preserve faults!
1050 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1051 if (LHS->equalsInt(0))
1052 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1058 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
1059 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1060 if (I.getType()->isSigned())
1061 if (Value *RHSNeg = dyn_castNegVal(Op1))
1062 if (!isa<ConstantSInt>(RHSNeg) ||
1063 cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
1065 AddUsesToWorkList(I);
1066 I.setOperand(1, RHSNeg);
1070 if (isa<UndefValue>(Op0)) // undef % X -> 0
1071 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1072 if (isa<UndefValue>(Op1))
1073 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
1075 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1076 if (RHS->equalsInt(1)) // X % 1 == 0
1077 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1079 // Check to see if this is an unsigned remainder with an exact power of 2,
1080 // if so, convert to a bitwise and.
1081 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1082 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
1083 if (!(Val & (Val-1))) // Power of 2
1084 return BinaryOperator::createAnd(Op0,
1085 ConstantUInt::get(I.getType(), Val-1));
1087 if (!RHS->isNullValue()) {
1088 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1089 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1091 if (isa<PHINode>(Op0))
1092 if (Instruction *NV = FoldOpIntoPhi(I))
1097 // If this is 'urem X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1098 // transform this into: '(Cond ? (urem X, C1) : (urem X, C2))'.
1099 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1100 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1101 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1102 if (STO->getValue() == 0) { // Couldn't be this argument.
1103 I.setOperand(1, SFO);
1105 } else if (SFO->getValue() == 0) {
1106 I.setOperand(1, STO);
1110 if (!(STO->getValue() & (STO->getValue()-1)) &&
1111 !(SFO->getValue() & (SFO->getValue()-1))) {
1112 Value *TrueAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1113 SubOne(STO), SI->getName()+".t"), I);
1114 Value *FalseAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1115 SubOne(SFO), SI->getName()+".f"), I);
1116 return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
1120 // 0 % X == 0, we don't need to preserve faults!
1121 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1122 if (LHS->equalsInt(0))
1123 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1128 // isMaxValueMinusOne - return true if this is Max-1
1129 static bool isMaxValueMinusOne(const ConstantInt *C) {
1130 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
1131 // Calculate -1 casted to the right type...
1132 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
1133 uint64_t Val = ~0ULL; // All ones
1134 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1135 return CU->getValue() == Val-1;
1138 const ConstantSInt *CS = cast<ConstantSInt>(C);
1140 // Calculate 0111111111..11111
1141 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
1142 int64_t Val = INT64_MAX; // All ones
1143 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1144 return CS->getValue() == Val-1;
1147 // isMinValuePlusOne - return true if this is Min+1
1148 static bool isMinValuePlusOne(const ConstantInt *C) {
1149 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1150 return CU->getValue() == 1;
1152 const ConstantSInt *CS = cast<ConstantSInt>(C);
1154 // Calculate 1111111111000000000000
1155 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
1156 int64_t Val = -1; // All ones
1157 Val <<= TypeBits-1; // Shift over to the right spot
1158 return CS->getValue() == Val+1;
1161 // isOneBitSet - Return true if there is exactly one bit set in the specified
1163 static bool isOneBitSet(const ConstantInt *CI) {
1164 uint64_t V = CI->getRawValue();
1165 return V && (V & (V-1)) == 0;
1168 #if 0 // Currently unused
1169 // isLowOnes - Return true if the constant is of the form 0+1+.
1170 static bool isLowOnes(const ConstantInt *CI) {
1171 uint64_t V = CI->getRawValue();
1173 // There won't be bits set in parts that the type doesn't contain.
1174 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1176 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1177 return U && V && (U & V) == 0;
1181 // isHighOnes - Return true if the constant is of the form 1+0+.
1182 // This is the same as lowones(~X).
1183 static bool isHighOnes(const ConstantInt *CI) {
1184 uint64_t V = ~CI->getRawValue();
1186 // There won't be bits set in parts that the type doesn't contain.
1187 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1189 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1190 return U && V && (U & V) == 0;
1194 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
1195 /// are carefully arranged to allow folding of expressions such as:
1197 /// (A < B) | (A > B) --> (A != B)
1199 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
1200 /// represents that the comparison is true if A == B, and bit value '1' is true
1203 static unsigned getSetCondCode(const SetCondInst *SCI) {
1204 switch (SCI->getOpcode()) {
1206 case Instruction::SetGT: return 1;
1207 case Instruction::SetEQ: return 2;
1208 case Instruction::SetGE: return 3;
1209 case Instruction::SetLT: return 4;
1210 case Instruction::SetNE: return 5;
1211 case Instruction::SetLE: return 6;
1214 assert(0 && "Invalid SetCC opcode!");
1219 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
1220 /// opcode and two operands into either a constant true or false, or a brand new
1221 /// SetCC instruction.
1222 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
1224 case 0: return ConstantBool::False;
1225 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
1226 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
1227 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
1228 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
1229 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
1230 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
1231 case 7: return ConstantBool::True;
1232 default: assert(0 && "Illegal SetCCCode!"); return 0;
1236 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1237 struct FoldSetCCLogical {
1240 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
1241 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
1242 bool shouldApply(Value *V) const {
1243 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
1244 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
1245 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
1248 Instruction *apply(BinaryOperator &Log) const {
1249 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
1250 if (SCI->getOperand(0) != LHS) {
1251 assert(SCI->getOperand(1) == LHS);
1252 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
1255 unsigned LHSCode = getSetCondCode(SCI);
1256 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
1258 switch (Log.getOpcode()) {
1259 case Instruction::And: Code = LHSCode & RHSCode; break;
1260 case Instruction::Or: Code = LHSCode | RHSCode; break;
1261 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
1262 default: assert(0 && "Illegal logical opcode!"); return 0;
1265 Value *RV = getSetCCValue(Code, LHS, RHS);
1266 if (Instruction *I = dyn_cast<Instruction>(RV))
1268 // Otherwise, it's a constant boolean value...
1269 return IC.ReplaceInstUsesWith(Log, RV);
1274 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
1275 /// this predicate to simplify operations downstream. V and Mask are known to
1276 /// be the same type.
1277 static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask) {
1278 if (isa<UndefValue>(V) || Mask->isNullValue())
1280 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
1281 return ConstantExpr::getAnd(CI, Mask)->isNullValue();
1283 if (Instruction *I = dyn_cast<Instruction>(V)) {
1284 switch (I->getOpcode()) {
1285 case Instruction::And:
1286 // (X & C1) & C2 == 0 iff C1 & C2 == 0.
1287 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1)))
1288 if (ConstantExpr::getAnd(CI, Mask)->isNullValue())
1291 case Instruction::Cast: {
1292 const Type *SrcTy = I->getOperand(0)->getType();
1293 if (SrcTy->isIntegral()) {
1294 // (cast <ty> X to int) & C2 == 0 iff <ty> could not have contained C2.
1295 if (SrcTy->isUnsigned() && // Only handle zero ext.
1296 ConstantExpr::getCast(Mask, SrcTy)->isNullValue())
1299 // If this is a noop cast, recurse.
1300 if (SrcTy != Type::BoolTy)
1301 if ((SrcTy->isSigned() && SrcTy->getUnsignedVersion() ==I->getType()) ||
1302 SrcTy->getSignedVersion() == I->getType()) {
1304 ConstantExpr::getCast(Mask, I->getOperand(0)->getType());
1305 return MaskedValueIsZero(I->getOperand(0),
1306 cast<ConstantIntegral>(NewMask));
1311 case Instruction::Shl:
1312 // (shl X, C1) & C2 == 0 iff (-1 << C1) & C2 == 0
1313 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1))) {
1314 Constant *C1 = ConstantIntegral::getAllOnesValue(I->getType());
1315 C1 = ConstantExpr::getShl(C1, SA);
1316 C1 = ConstantExpr::getAnd(C1, Mask);
1317 if (C1->isNullValue())
1321 case Instruction::Shr:
1322 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
1323 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
1324 if (I->getType()->isUnsigned()) {
1325 Constant *C1 = ConstantIntegral::getAllOnesValue(I->getType());
1326 C1 = ConstantExpr::getShr(C1, SA);
1327 C1 = ConstantExpr::getAnd(C1, Mask);
1328 if (C1->isNullValue())
1338 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
1339 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
1340 // guaranteed to be either a shift instruction or a binary operator.
1341 Instruction *InstCombiner::OptAndOp(Instruction *Op,
1342 ConstantIntegral *OpRHS,
1343 ConstantIntegral *AndRHS,
1344 BinaryOperator &TheAnd) {
1345 Value *X = Op->getOperand(0);
1346 Constant *Together = 0;
1347 if (!isa<ShiftInst>(Op))
1348 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
1350 switch (Op->getOpcode()) {
1351 case Instruction::Xor:
1352 if (Op->hasOneUse()) {
1353 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
1354 std::string OpName = Op->getName(); Op->setName("");
1355 Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
1356 InsertNewInstBefore(And, TheAnd);
1357 return BinaryOperator::createXor(And, Together);
1360 case Instruction::Or:
1361 if (Together == AndRHS) // (X | C) & C --> C
1362 return ReplaceInstUsesWith(TheAnd, AndRHS);
1364 if (Op->hasOneUse() && Together != OpRHS) {
1365 // (X | C1) & C2 --> (X | (C1&C2)) & C2
1366 std::string Op0Name = Op->getName(); Op->setName("");
1367 Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
1368 InsertNewInstBefore(Or, TheAnd);
1369 return BinaryOperator::createAnd(Or, AndRHS);
1372 case Instruction::Add:
1373 if (Op->hasOneUse()) {
1374 // Adding a one to a single bit bit-field should be turned into an XOR
1375 // of the bit. First thing to check is to see if this AND is with a
1376 // single bit constant.
1377 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
1379 // Clear bits that are not part of the constant.
1380 AndRHSV &= (1ULL << AndRHS->getType()->getPrimitiveSize()*8)-1;
1382 // If there is only one bit set...
1383 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
1384 // Ok, at this point, we know that we are masking the result of the
1385 // ADD down to exactly one bit. If the constant we are adding has
1386 // no bits set below this bit, then we can eliminate the ADD.
1387 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
1389 // Check to see if any bits below the one bit set in AndRHSV are set.
1390 if ((AddRHS & (AndRHSV-1)) == 0) {
1391 // If not, the only thing that can effect the output of the AND is
1392 // the bit specified by AndRHSV. If that bit is set, the effect of
1393 // the XOR is to toggle the bit. If it is clear, then the ADD has
1395 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
1396 TheAnd.setOperand(0, X);
1399 std::string Name = Op->getName(); Op->setName("");
1400 // Pull the XOR out of the AND.
1401 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
1402 InsertNewInstBefore(NewAnd, TheAnd);
1403 return BinaryOperator::createXor(NewAnd, AndRHS);
1410 case Instruction::Shl: {
1411 // We know that the AND will not produce any of the bits shifted in, so if
1412 // the anded constant includes them, clear them now!
1414 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1415 Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
1416 Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
1418 if (CI == ShlMask) { // Masking out bits that the shift already masks
1419 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
1420 } else if (CI != AndRHS) { // Reducing bits set in and.
1421 TheAnd.setOperand(1, CI);
1426 case Instruction::Shr:
1427 // We know that the AND will not produce any of the bits shifted in, so if
1428 // the anded constant includes them, clear them now! This only applies to
1429 // unsigned shifts, because a signed shr may bring in set bits!
1431 if (AndRHS->getType()->isUnsigned()) {
1432 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1433 Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS);
1434 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1436 if (CI == ShrMask) { // Masking out bits that the shift already masks.
1437 return ReplaceInstUsesWith(TheAnd, Op);
1438 } else if (CI != AndRHS) {
1439 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
1442 } else { // Signed shr.
1443 // See if this is shifting in some sign extension, then masking it out
1445 if (Op->hasOneUse()) {
1446 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1447 Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS);
1448 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1449 if (CI == AndRHS) { // Masking out bits shifted in.
1450 // Make the argument unsigned.
1451 Value *ShVal = Op->getOperand(0);
1452 ShVal = InsertCastBefore(ShVal,
1453 ShVal->getType()->getUnsignedVersion(),
1455 ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal,
1456 OpRHS, Op->getName()),
1458 Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType());
1459 ShVal = InsertNewInstBefore(BinaryOperator::createAnd(ShVal, AndRHS2,
1462 return new CastInst(ShVal, Op->getType());
1472 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
1473 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
1474 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. IB is the location to
1475 /// insert new instructions.
1476 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
1477 bool Inside, Instruction &IB) {
1478 assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
1479 "Lo is not <= Hi in range emission code!");
1481 if (Lo == Hi) // Trivially false.
1482 return new SetCondInst(Instruction::SetNE, V, V);
1483 if (cast<ConstantIntegral>(Lo)->isMinValue())
1484 return new SetCondInst(Instruction::SetLT, V, Hi);
1486 Constant *AddCST = ConstantExpr::getNeg(Lo);
1487 Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
1488 InsertNewInstBefore(Add, IB);
1489 // Convert to unsigned for the comparison.
1490 const Type *UnsType = Add->getType()->getUnsignedVersion();
1491 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1492 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1493 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1494 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1497 if (Lo == Hi) // Trivially true.
1498 return new SetCondInst(Instruction::SetEQ, V, V);
1500 Hi = SubOne(cast<ConstantInt>(Hi));
1501 if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
1502 return new SetCondInst(Instruction::SetGT, V, Hi);
1504 // Emit X-Lo > Hi-Lo-1
1505 Constant *AddCST = ConstantExpr::getNeg(Lo);
1506 Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
1507 InsertNewInstBefore(Add, IB);
1508 // Convert to unsigned for the comparison.
1509 const Type *UnsType = Add->getType()->getUnsignedVersion();
1510 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1511 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1512 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1513 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1517 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1518 bool Changed = SimplifyCommutative(I);
1519 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1521 if (isa<UndefValue>(Op1)) // X & undef -> 0
1522 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1526 return ReplaceInstUsesWith(I, Op1);
1529 if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) {
1530 if (AndRHS->isAllOnesValue()) // and X, -1 == X
1531 return ReplaceInstUsesWith(I, Op0);
1533 if (MaskedValueIsZero(Op0, AndRHS)) // LHS & RHS == 0
1534 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1536 // If the mask is not masking out any bits, there is no reason to do the
1537 // and in the first place.
1538 if (MaskedValueIsZero(Op0,
1539 cast<ConstantIntegral>(ConstantExpr::getNot(AndRHS))))
1540 return ReplaceInstUsesWith(I, Op0);
1542 // Optimize a variety of ((val OP C1) & C2) combinations...
1543 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
1544 Instruction *Op0I = cast<Instruction>(Op0);
1545 Value *Op0LHS = Op0I->getOperand(0);
1546 Value *Op0RHS = Op0I->getOperand(1);
1547 switch (Op0I->getOpcode()) {
1548 case Instruction::Xor:
1549 case Instruction::Or:
1550 // (X ^ V) & C2 --> (X & C2) iff (V & C2) == 0
1551 // (X | V) & C2 --> (X & C2) iff (V & C2) == 0
1552 if (MaskedValueIsZero(Op0LHS, AndRHS))
1553 return BinaryOperator::createAnd(Op0RHS, AndRHS);
1554 if (MaskedValueIsZero(Op0RHS, AndRHS))
1555 return BinaryOperator::createAnd(Op0LHS, AndRHS);
1557 case Instruction::And:
1558 // (X & V) & C2 --> 0 iff (V & C2) == 0
1559 if (MaskedValueIsZero(Op0LHS, AndRHS) ||
1560 MaskedValueIsZero(Op0RHS, AndRHS))
1561 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1565 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1566 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
1568 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
1569 const Type *SrcTy = CI->getOperand(0)->getType();
1571 // If this is an integer sign or zero extension instruction.
1572 if (SrcTy->isIntegral() &&
1573 SrcTy->getPrimitiveSize() < CI->getType()->getPrimitiveSize()) {
1575 if (SrcTy->isUnsigned()) {
1576 // See if this and is clearing out bits that are known to be zero
1577 // anyway (due to the zero extension).
1578 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1579 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1580 Constant *Result = ConstantExpr::getAnd(Mask, AndRHS);
1581 if (Result == Mask) // The "and" isn't doing anything, remove it.
1582 return ReplaceInstUsesWith(I, CI);
1583 if (Result != AndRHS) { // Reduce the and RHS constant.
1584 I.setOperand(1, Result);
1589 if (CI->hasOneUse() && SrcTy->isInteger()) {
1590 // We can only do this if all of the sign bits brought in are masked
1591 // out. Compute this by first getting 0000011111, then inverting
1593 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1594 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1595 Mask = ConstantExpr::getNot(Mask); // 1's in the new bits.
1596 if (ConstantExpr::getAnd(Mask, AndRHS)->isNullValue()) {
1597 // If the and is clearing all of the sign bits, change this to a
1598 // zero extension cast. To do this, cast the cast input to
1599 // unsigned, then to the requested size.
1600 Value *CastOp = CI->getOperand(0);
1602 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
1603 CI->getName()+".uns");
1604 NC = InsertNewInstBefore(NC, I);
1605 // Finally, insert a replacement for CI.
1606 NC = new CastInst(NC, CI->getType(), CI->getName());
1608 NC = InsertNewInstBefore(NC, I);
1609 WorkList.push_back(CI); // Delete CI later.
1610 I.setOperand(0, NC);
1611 return &I; // The AND operand was modified.
1618 // Try to fold constant and into select arguments.
1619 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1620 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1622 if (isa<PHINode>(Op0))
1623 if (Instruction *NV = FoldOpIntoPhi(I))
1627 Value *Op0NotVal = dyn_castNotVal(Op0);
1628 Value *Op1NotVal = dyn_castNotVal(Op1);
1630 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1631 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1633 // (~A & ~B) == (~(A | B)) - De Morgan's Law
1634 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1635 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
1636 I.getName()+".demorgan");
1637 InsertNewInstBefore(Or, I);
1638 return BinaryOperator::createNot(Or);
1641 if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
1642 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1643 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1646 Value *LHSVal, *RHSVal;
1647 ConstantInt *LHSCst, *RHSCst;
1648 Instruction::BinaryOps LHSCC, RHSCC;
1649 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1650 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1651 if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
1652 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1653 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1654 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1655 // Ensure that the larger constant is on the RHS.
1656 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1657 SetCondInst *LHS = cast<SetCondInst>(Op0);
1658 if (cast<ConstantBool>(Cmp)->getValue()) {
1659 std::swap(LHS, RHS);
1660 std::swap(LHSCst, RHSCst);
1661 std::swap(LHSCC, RHSCC);
1664 // At this point, we know we have have two setcc instructions
1665 // comparing a value against two constants and and'ing the result
1666 // together. Because of the above check, we know that we only have
1667 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1668 // FoldSetCCLogical check above), that the two constants are not
1670 assert(LHSCst != RHSCst && "Compares not folded above?");
1673 default: assert(0 && "Unknown integer condition code!");
1674 case Instruction::SetEQ:
1676 default: assert(0 && "Unknown integer condition code!");
1677 case Instruction::SetEQ: // (X == 13 & X == 15) -> false
1678 case Instruction::SetGT: // (X == 13 & X > 15) -> false
1679 return ReplaceInstUsesWith(I, ConstantBool::False);
1680 case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
1681 case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
1682 return ReplaceInstUsesWith(I, LHS);
1684 case Instruction::SetNE:
1686 default: assert(0 && "Unknown integer condition code!");
1687 case Instruction::SetLT:
1688 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
1689 return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
1690 break; // (X != 13 & X < 15) -> no change
1691 case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
1692 case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
1693 return ReplaceInstUsesWith(I, RHS);
1694 case Instruction::SetNE:
1695 if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
1696 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1697 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
1698 LHSVal->getName()+".off");
1699 InsertNewInstBefore(Add, I);
1700 const Type *UnsType = Add->getType()->getUnsignedVersion();
1701 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
1702 AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
1703 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1704 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1706 break; // (X != 13 & X != 15) -> no change
1709 case Instruction::SetLT:
1711 default: assert(0 && "Unknown integer condition code!");
1712 case Instruction::SetEQ: // (X < 13 & X == 15) -> false
1713 case Instruction::SetGT: // (X < 13 & X > 15) -> false
1714 return ReplaceInstUsesWith(I, ConstantBool::False);
1715 case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
1716 case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
1717 return ReplaceInstUsesWith(I, LHS);
1719 case Instruction::SetGT:
1721 default: assert(0 && "Unknown integer condition code!");
1722 case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
1723 return ReplaceInstUsesWith(I, LHS);
1724 case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
1725 return ReplaceInstUsesWith(I, RHS);
1726 case Instruction::SetNE:
1727 if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
1728 return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
1729 break; // (X > 13 & X != 15) -> no change
1730 case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
1731 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
1737 return Changed ? &I : 0;
1740 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
1741 bool Changed = SimplifyCommutative(I);
1742 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1744 if (isa<UndefValue>(Op1))
1745 return ReplaceInstUsesWith(I, // X | undef -> -1
1746 ConstantIntegral::getAllOnesValue(I.getType()));
1748 // or X, X = X or X, 0 == X
1749 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
1750 return ReplaceInstUsesWith(I, Op0);
1753 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1754 // If X is known to only contain bits that already exist in RHS, just
1755 // replace this instruction with RHS directly.
1756 if (MaskedValueIsZero(Op0,
1757 cast<ConstantIntegral>(ConstantExpr::getNot(RHS))))
1758 return ReplaceInstUsesWith(I, RHS);
1760 ConstantInt *C1; Value *X;
1761 // (X & C1) | C2 --> (X | C2) & (C1|C2)
1762 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1763 std::string Op0Name = Op0->getName(); Op0->setName("");
1764 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
1765 InsertNewInstBefore(Or, I);
1766 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
1769 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
1770 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1771 std::string Op0Name = Op0->getName(); Op0->setName("");
1772 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
1773 InsertNewInstBefore(Or, I);
1774 return BinaryOperator::createXor(Or,
1775 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
1778 // Try to fold constant and into select arguments.
1779 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1780 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1782 if (isa<PHINode>(Op0))
1783 if (Instruction *NV = FoldOpIntoPhi(I))
1787 // (A & C1)|(A & C2) == A & (C1|C2)
1788 Value *A, *B; ConstantInt *C1, *C2;
1789 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
1790 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) && A == B)
1791 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
1793 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
1794 if (A == Op1) // ~A | A == -1
1795 return ReplaceInstUsesWith(I,
1796 ConstantIntegral::getAllOnesValue(I.getType()));
1801 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
1803 return ReplaceInstUsesWith(I,
1804 ConstantIntegral::getAllOnesValue(I.getType()));
1806 // (~A | ~B) == (~(A & B)) - De Morgan's Law
1807 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1808 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
1809 I.getName()+".demorgan"), I);
1810 return BinaryOperator::createNot(And);
1814 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
1815 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
1816 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1819 Value *LHSVal, *RHSVal;
1820 ConstantInt *LHSCst, *RHSCst;
1821 Instruction::BinaryOps LHSCC, RHSCC;
1822 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1823 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1824 if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
1825 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1826 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1827 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1828 // Ensure that the larger constant is on the RHS.
1829 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1830 SetCondInst *LHS = cast<SetCondInst>(Op0);
1831 if (cast<ConstantBool>(Cmp)->getValue()) {
1832 std::swap(LHS, RHS);
1833 std::swap(LHSCst, RHSCst);
1834 std::swap(LHSCC, RHSCC);
1837 // At this point, we know we have have two setcc instructions
1838 // comparing a value against two constants and or'ing the result
1839 // together. Because of the above check, we know that we only have
1840 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1841 // FoldSetCCLogical check above), that the two constants are not
1843 assert(LHSCst != RHSCst && "Compares not folded above?");
1846 default: assert(0 && "Unknown integer condition code!");
1847 case Instruction::SetEQ:
1849 default: assert(0 && "Unknown integer condition code!");
1850 case Instruction::SetEQ:
1851 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
1852 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1853 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
1854 LHSVal->getName()+".off");
1855 InsertNewInstBefore(Add, I);
1856 const Type *UnsType = Add->getType()->getUnsignedVersion();
1857 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
1858 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
1859 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1860 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1862 break; // (X == 13 | X == 15) -> no change
1864 case Instruction::SetGT:
1865 if (LHSCst == SubOne(RHSCst)) // (X == 13 | X > 14) -> X > 13
1866 return new SetCondInst(Instruction::SetGT, LHSVal, LHSCst);
1867 break; // (X == 13 | X > 15) -> no change
1868 case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
1869 case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
1870 return ReplaceInstUsesWith(I, RHS);
1873 case Instruction::SetNE:
1875 default: assert(0 && "Unknown integer condition code!");
1876 case Instruction::SetLT: // (X != 13 | X < 15) -> X < 15
1877 return ReplaceInstUsesWith(I, RHS);
1878 case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
1879 case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
1880 return ReplaceInstUsesWith(I, LHS);
1881 case Instruction::SetNE: // (X != 13 | X != 15) -> true
1882 return ReplaceInstUsesWith(I, ConstantBool::True);
1885 case Instruction::SetLT:
1887 default: assert(0 && "Unknown integer condition code!");
1888 case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
1890 case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
1891 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
1892 case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
1893 case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
1894 return ReplaceInstUsesWith(I, RHS);
1897 case Instruction::SetGT:
1899 default: assert(0 && "Unknown integer condition code!");
1900 case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
1901 case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
1902 return ReplaceInstUsesWith(I, LHS);
1903 case Instruction::SetNE: // (X > 13 | X != 15) -> true
1904 case Instruction::SetLT: // (X > 13 | X < 15) -> true
1905 return ReplaceInstUsesWith(I, ConstantBool::True);
1910 return Changed ? &I : 0;
1913 // XorSelf - Implements: X ^ X --> 0
1916 XorSelf(Value *rhs) : RHS(rhs) {}
1917 bool shouldApply(Value *LHS) const { return LHS == RHS; }
1918 Instruction *apply(BinaryOperator &Xor) const {
1924 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
1925 bool Changed = SimplifyCommutative(I);
1926 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1928 if (isa<UndefValue>(Op1))
1929 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
1931 // xor X, X = 0, even if X is nested in a sequence of Xor's.
1932 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
1933 assert(Result == &I && "AssociativeOpt didn't work?");
1934 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1937 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1939 if (RHS->isNullValue())
1940 return ReplaceInstUsesWith(I, Op0);
1942 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
1943 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
1944 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
1945 if (RHS == ConstantBool::True && SCI->hasOneUse())
1946 return new SetCondInst(SCI->getInverseCondition(),
1947 SCI->getOperand(0), SCI->getOperand(1));
1949 // ~(c-X) == X-c-1 == X+(-c-1)
1950 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
1951 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
1952 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
1953 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
1954 ConstantInt::get(I.getType(), 1));
1955 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
1958 // ~(~X & Y) --> (X | ~Y)
1959 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
1960 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
1961 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
1963 BinaryOperator::createNot(Op0I->getOperand(1),
1964 Op0I->getOperand(1)->getName()+".not");
1965 InsertNewInstBefore(NotY, I);
1966 return BinaryOperator::createOr(Op0NotVal, NotY);
1970 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1971 switch (Op0I->getOpcode()) {
1972 case Instruction::Add:
1973 // ~(X-c) --> (-c-1)-X
1974 if (RHS->isAllOnesValue()) {
1975 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
1976 return BinaryOperator::createSub(
1977 ConstantExpr::getSub(NegOp0CI,
1978 ConstantInt::get(I.getType(), 1)),
1979 Op0I->getOperand(0));
1982 case Instruction::And:
1983 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
1984 if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue())
1985 return BinaryOperator::createOr(Op0, RHS);
1987 case Instruction::Or:
1988 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
1989 if (ConstantExpr::getAnd(RHS, Op0CI) == RHS)
1990 return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS));
1996 // Try to fold constant and into select arguments.
1997 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1998 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2000 if (isa<PHINode>(Op0))
2001 if (Instruction *NV = FoldOpIntoPhi(I))
2005 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
2007 return ReplaceInstUsesWith(I,
2008 ConstantIntegral::getAllOnesValue(I.getType()));
2010 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
2012 return ReplaceInstUsesWith(I,
2013 ConstantIntegral::getAllOnesValue(I.getType()));
2015 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
2016 if (Op1I->getOpcode() == Instruction::Or) {
2017 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
2018 cast<BinaryOperator>(Op1I)->swapOperands();
2020 std::swap(Op0, Op1);
2021 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
2023 std::swap(Op0, Op1);
2025 } else if (Op1I->getOpcode() == Instruction::Xor) {
2026 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
2027 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
2028 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
2029 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
2032 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
2033 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
2034 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
2035 cast<BinaryOperator>(Op0I)->swapOperands();
2036 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
2037 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
2038 Op1->getName()+".not"), I);
2039 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
2041 } else if (Op0I->getOpcode() == Instruction::Xor) {
2042 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
2043 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2044 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
2045 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2048 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
2049 Value *A, *B; ConstantInt *C1, *C2;
2050 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2051 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) &&
2052 ConstantExpr::getAnd(C1, C2)->isNullValue())
2053 return BinaryOperator::createOr(Op0, Op1);
2055 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
2056 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
2057 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2060 return Changed ? &I : 0;
2063 /// MulWithOverflow - Compute Result = In1*In2, returning true if the result
2064 /// overflowed for this type.
2065 static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2067 Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
2068 return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
2071 static bool isPositive(ConstantInt *C) {
2072 return cast<ConstantSInt>(C)->getValue() >= 0;
2075 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
2076 /// overflowed for this type.
2077 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2079 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
2081 if (In1->getType()->isUnsigned())
2082 return cast<ConstantUInt>(Result)->getValue() <
2083 cast<ConstantUInt>(In1)->getValue();
2084 if (isPositive(In1) != isPositive(In2))
2086 if (isPositive(In1))
2087 return cast<ConstantSInt>(Result)->getValue() <
2088 cast<ConstantSInt>(In1)->getValue();
2089 return cast<ConstantSInt>(Result)->getValue() >
2090 cast<ConstantSInt>(In1)->getValue();
2093 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
2094 /// code necessary to compute the offset from the base pointer (without adding
2095 /// in the base pointer). Return the result as a signed integer of intptr size.
2096 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
2097 TargetData &TD = IC.getTargetData();
2098 gep_type_iterator GTI = gep_type_begin(GEP);
2099 const Type *UIntPtrTy = TD.getIntPtrType();
2100 const Type *SIntPtrTy = UIntPtrTy->getSignedVersion();
2101 Value *Result = Constant::getNullValue(SIntPtrTy);
2103 // Build a mask for high order bits.
2104 uint64_t PtrSizeMask = ~0ULL;
2105 PtrSizeMask >>= 64-(TD.getPointerSize()*8);
2107 ++GTI; // Measure type stepping over.
2108 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
2109 Value *Op = GEP->getOperand(i);
2110 uint64_t Size = TD.getTypeSize(*GTI) & PtrSizeMask;
2111 Constant *Scale = ConstantExpr::getCast(ConstantUInt::get(UIntPtrTy, Size),
2113 if (Constant *OpC = dyn_cast<Constant>(Op)) {
2114 if (!OpC->isNullValue()) {
2115 Scale = ConstantExpr::getMul(OpC, Scale);
2116 if (Constant *RC = dyn_cast<Constant>(Result))
2117 Result = ConstantExpr::getAdd(RC, Scale);
2119 // Emit an add instruction.
2120 Result = IC.InsertNewInstBefore(
2121 BinaryOperator::createAdd(Result, Scale,
2122 GEP->getName()+".offs"), I);
2126 // We'll let instcombine(mul) convert this to a shl if possible.
2128 IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
2129 GEP->getName()+".idx"), I);
2131 // Emit an add instruction.
2132 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Offs, Result,
2133 GEP->getName()+".offs"), I);
2139 /// FoldGEPSetCC - Fold comparisons between a GEP instruction and something
2140 /// else. At this point we know that the GEP is on the LHS of the comparison.
2141 Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS,
2142 Instruction::BinaryOps Cond,
2144 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
2146 Value *PtrBase = GEPLHS->getOperand(0);
2147 if (PtrBase == RHS) {
2148 // As an optimization, we don't actually have to compute the actual value of
2149 // OFFSET if this is a seteq or setne comparison, just return whether each
2150 // index is zero or not.
2152 // Only lower this if the setcc is the only user of the GEP or if we expect
2153 // the result to fold to a constant!
2154 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
2155 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
2156 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
2157 return new SetCondInst(Cond, Offset,
2158 Constant::getNullValue(Offset->getType()));
2160 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
2161 if (PtrBase != GEPRHS->getOperand(0))
2164 // Only lower this if the setcc is the only user of the GEP or if we expect
2165 // the result to fold to a constant!
2166 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
2167 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
2168 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
2169 Value *L = EmitGEPOffset(GEPLHS, I, *this);
2170 Value *R = EmitGEPOffset(GEPRHS, I, *this);
2171 return new SetCondInst(Cond, L, R);
2178 Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
2179 bool Changed = SimplifyCommutative(I);
2180 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2181 const Type *Ty = Op0->getType();
2185 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
2187 if (isa<UndefValue>(Op1)) // X setcc undef -> undef
2188 return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
2190 // setcc <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
2191 // addresses never equal each other! We already know that Op0 != Op1.
2192 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
2193 isa<ConstantPointerNull>(Op0)) &&
2194 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
2195 isa<ConstantPointerNull>(Op1)))
2196 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
2198 // setcc's with boolean values can always be turned into bitwise operations
2199 if (Ty == Type::BoolTy) {
2200 switch (I.getOpcode()) {
2201 default: assert(0 && "Invalid setcc instruction!");
2202 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
2203 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
2204 InsertNewInstBefore(Xor, I);
2205 return BinaryOperator::createNot(Xor);
2207 case Instruction::SetNE:
2208 return BinaryOperator::createXor(Op0, Op1);
2210 case Instruction::SetGT:
2211 std::swap(Op0, Op1); // Change setgt -> setlt
2213 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
2214 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2215 InsertNewInstBefore(Not, I);
2216 return BinaryOperator::createAnd(Not, Op1);
2218 case Instruction::SetGE:
2219 std::swap(Op0, Op1); // Change setge -> setle
2221 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
2222 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2223 InsertNewInstBefore(Not, I);
2224 return BinaryOperator::createOr(Not, Op1);
2229 // See if we are doing a comparison between a constant and an instruction that
2230 // can be folded into the comparison.
2231 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2232 // Check to see if we are comparing against the minimum or maximum value...
2233 if (CI->isMinValue()) {
2234 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
2235 return ReplaceInstUsesWith(I, ConstantBool::False);
2236 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
2237 return ReplaceInstUsesWith(I, ConstantBool::True);
2238 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
2239 return BinaryOperator::createSetEQ(Op0, Op1);
2240 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
2241 return BinaryOperator::createSetNE(Op0, Op1);
2243 } else if (CI->isMaxValue()) {
2244 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
2245 return ReplaceInstUsesWith(I, ConstantBool::False);
2246 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
2247 return ReplaceInstUsesWith(I, ConstantBool::True);
2248 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
2249 return BinaryOperator::createSetEQ(Op0, Op1);
2250 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
2251 return BinaryOperator::createSetNE(Op0, Op1);
2253 // Comparing against a value really close to min or max?
2254 } else if (isMinValuePlusOne(CI)) {
2255 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
2256 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
2257 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
2258 return BinaryOperator::createSetNE(Op0, SubOne(CI));
2260 } else if (isMaxValueMinusOne(CI)) {
2261 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
2262 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
2263 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
2264 return BinaryOperator::createSetNE(Op0, AddOne(CI));
2267 // If we still have a setle or setge instruction, turn it into the
2268 // appropriate setlt or setgt instruction. Since the border cases have
2269 // already been handled above, this requires little checking.
2271 if (I.getOpcode() == Instruction::SetLE)
2272 return BinaryOperator::createSetLT(Op0, AddOne(CI));
2273 if (I.getOpcode() == Instruction::SetGE)
2274 return BinaryOperator::createSetGT(Op0, SubOne(CI));
2276 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
2277 switch (LHSI->getOpcode()) {
2278 case Instruction::PHI:
2279 if (Instruction *NV = FoldOpIntoPhi(I))
2282 case Instruction::And:
2283 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
2284 LHSI->getOperand(0)->hasOneUse()) {
2285 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
2286 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
2287 // happens a LOT in code produced by the C front-end, for bitfield
2289 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
2290 ConstantUInt *ShAmt;
2291 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
2292 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
2293 const Type *Ty = LHSI->getType();
2295 // We can fold this as long as we can't shift unknown bits
2296 // into the mask. This can only happen with signed shift
2297 // rights, as they sign-extend.
2299 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
2300 Shift->getType()->isUnsigned();
2302 // To test for the bad case of the signed shr, see if any
2303 // of the bits shifted in could be tested after the mask.
2304 Constant *OShAmt = ConstantUInt::get(Type::UByteTy,
2305 Ty->getPrimitiveSize()*8-ShAmt->getValue());
2307 ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
2308 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
2314 if (Shift->getOpcode() == Instruction::Shl)
2315 NewCst = ConstantExpr::getUShr(CI, ShAmt);
2317 NewCst = ConstantExpr::getShl(CI, ShAmt);
2319 // Check to see if we are shifting out any of the bits being
2321 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
2322 // If we shifted bits out, the fold is not going to work out.
2323 // As a special case, check to see if this means that the
2324 // result is always true or false now.
2325 if (I.getOpcode() == Instruction::SetEQ)
2326 return ReplaceInstUsesWith(I, ConstantBool::False);
2327 if (I.getOpcode() == Instruction::SetNE)
2328 return ReplaceInstUsesWith(I, ConstantBool::True);
2330 I.setOperand(1, NewCst);
2331 Constant *NewAndCST;
2332 if (Shift->getOpcode() == Instruction::Shl)
2333 NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
2335 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
2336 LHSI->setOperand(1, NewAndCST);
2337 LHSI->setOperand(0, Shift->getOperand(0));
2338 WorkList.push_back(Shift); // Shift is dead.
2339 AddUsesToWorkList(I);
2347 // (setcc (cast X to larger), CI)
2348 case Instruction::Cast: {
2349 Instruction* replacement =
2350 visitSetCondInstWithCastAndConstant(I,cast<CastInst>(LHSI),CI);
2356 case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
2357 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2358 switch (I.getOpcode()) {
2360 case Instruction::SetEQ:
2361 case Instruction::SetNE: {
2362 // If we are comparing against bits always shifted out, the
2363 // comparison cannot succeed.
2365 ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
2366 if (Comp != CI) {// Comparing against a bit that we know is zero.
2367 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2368 Constant *Cst = ConstantBool::get(IsSetNE);
2369 return ReplaceInstUsesWith(I, Cst);
2372 if (LHSI->hasOneUse()) {
2373 // Otherwise strength reduce the shift into an and.
2374 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2375 unsigned TypeBits = CI->getType()->getPrimitiveSize()*8;
2376 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
2379 if (CI->getType()->isUnsigned()) {
2380 Mask = ConstantUInt::get(CI->getType(), Val);
2381 } else if (ShAmtVal != 0) {
2382 Mask = ConstantSInt::get(CI->getType(), Val);
2384 Mask = ConstantInt::getAllOnesValue(CI->getType());
2388 BinaryOperator::createAnd(LHSI->getOperand(0),
2389 Mask, LHSI->getName()+".mask");
2390 Value *And = InsertNewInstBefore(AndI, I);
2391 return new SetCondInst(I.getOpcode(), And,
2392 ConstantExpr::getUShr(CI, ShAmt));
2399 case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
2400 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2401 switch (I.getOpcode()) {
2403 case Instruction::SetEQ:
2404 case Instruction::SetNE: {
2405 // If we are comparing against bits always shifted out, the
2406 // comparison cannot succeed.
2408 ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
2410 if (Comp != CI) {// Comparing against a bit that we know is zero.
2411 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2412 Constant *Cst = ConstantBool::get(IsSetNE);
2413 return ReplaceInstUsesWith(I, Cst);
2416 if (LHSI->hasOneUse() || CI->isNullValue()) {
2417 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2419 // Otherwise strength reduce the shift into an and.
2420 uint64_t Val = ~0ULL; // All ones.
2421 Val <<= ShAmtVal; // Shift over to the right spot.
2424 if (CI->getType()->isUnsigned()) {
2425 unsigned TypeBits = CI->getType()->getPrimitiveSize()*8;
2426 Val &= (1ULL << TypeBits)-1;
2427 Mask = ConstantUInt::get(CI->getType(), Val);
2429 Mask = ConstantSInt::get(CI->getType(), Val);
2433 BinaryOperator::createAnd(LHSI->getOperand(0),
2434 Mask, LHSI->getName()+".mask");
2435 Value *And = InsertNewInstBefore(AndI, I);
2436 return new SetCondInst(I.getOpcode(), And,
2437 ConstantExpr::getShl(CI, ShAmt));
2445 case Instruction::Div:
2446 // Fold: (div X, C1) op C2 -> range check
2447 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
2448 // Fold this div into the comparison, producing a range check.
2449 // Determine, based on the divide type, what the range is being
2450 // checked. If there is an overflow on the low or high side, remember
2451 // it, otherwise compute the range [low, hi) bounding the new value.
2452 bool LoOverflow = false, HiOverflow = 0;
2453 ConstantInt *LoBound = 0, *HiBound = 0;
2456 bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
2458 Instruction::BinaryOps Opcode = I.getOpcode();
2460 if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
2461 } else if (LHSI->getType()->isUnsigned()) { // udiv
2463 LoOverflow = ProdOV;
2464 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
2465 } else if (isPositive(DivRHS)) { // Divisor is > 0.
2466 if (CI->isNullValue()) { // (X / pos) op 0
2468 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
2470 } else if (isPositive(CI)) { // (X / pos) op pos
2472 LoOverflow = ProdOV;
2473 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
2474 } else { // (X / pos) op neg
2475 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
2476 LoOverflow = AddWithOverflow(LoBound, Prod,
2477 cast<ConstantInt>(DivRHSH));
2479 HiOverflow = ProdOV;
2481 } else { // Divisor is < 0.
2482 if (CI->isNullValue()) { // (X / neg) op 0
2483 LoBound = AddOne(DivRHS);
2484 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
2485 } else if (isPositive(CI)) { // (X / neg) op pos
2486 HiOverflow = LoOverflow = ProdOV;
2488 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
2489 HiBound = AddOne(Prod);
2490 } else { // (X / neg) op neg
2492 LoOverflow = HiOverflow = ProdOV;
2493 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
2496 // Dividing by a negate swaps the condition.
2497 Opcode = SetCondInst::getSwappedCondition(Opcode);
2501 Value *X = LHSI->getOperand(0);
2503 default: assert(0 && "Unhandled setcc opcode!");
2504 case Instruction::SetEQ:
2505 if (LoOverflow && HiOverflow)
2506 return ReplaceInstUsesWith(I, ConstantBool::False);
2507 else if (HiOverflow)
2508 return new SetCondInst(Instruction::SetGE, X, LoBound);
2509 else if (LoOverflow)
2510 return new SetCondInst(Instruction::SetLT, X, HiBound);
2512 return InsertRangeTest(X, LoBound, HiBound, true, I);
2513 case Instruction::SetNE:
2514 if (LoOverflow && HiOverflow)
2515 return ReplaceInstUsesWith(I, ConstantBool::True);
2516 else if (HiOverflow)
2517 return new SetCondInst(Instruction::SetLT, X, LoBound);
2518 else if (LoOverflow)
2519 return new SetCondInst(Instruction::SetGE, X, HiBound);
2521 return InsertRangeTest(X, LoBound, HiBound, false, I);
2522 case Instruction::SetLT:
2524 return ReplaceInstUsesWith(I, ConstantBool::False);
2525 return new SetCondInst(Instruction::SetLT, X, LoBound);
2526 case Instruction::SetGT:
2528 return ReplaceInstUsesWith(I, ConstantBool::False);
2529 return new SetCondInst(Instruction::SetGE, X, HiBound);
2534 case Instruction::Select:
2535 // If either operand of the select is a constant, we can fold the
2536 // comparison into the select arms, which will cause one to be
2537 // constant folded and the select turned into a bitwise or.
2538 Value *Op1 = 0, *Op2 = 0;
2539 if (LHSI->hasOneUse()) {
2540 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
2541 // Fold the known value into the constant operand.
2542 Op1 = ConstantExpr::get(I.getOpcode(), C, CI);
2543 // Insert a new SetCC of the other select operand.
2544 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
2545 LHSI->getOperand(2), CI,
2547 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
2548 // Fold the known value into the constant operand.
2549 Op2 = ConstantExpr::get(I.getOpcode(), C, CI);
2550 // Insert a new SetCC of the other select operand.
2551 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
2552 LHSI->getOperand(1), CI,
2558 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
2562 // Simplify seteq and setne instructions...
2563 if (I.getOpcode() == Instruction::SetEQ ||
2564 I.getOpcode() == Instruction::SetNE) {
2565 bool isSetNE = I.getOpcode() == Instruction::SetNE;
2567 // If the first operand is (and|or|xor) with a constant, and the second
2568 // operand is a constant, simplify a bit.
2569 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
2570 switch (BO->getOpcode()) {
2571 case Instruction::Rem:
2572 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
2573 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
2575 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1)
2577 Log2(cast<ConstantSInt>(BO->getOperand(1))->getValue())) {
2578 const Type *UTy = BO->getType()->getUnsignedVersion();
2579 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
2581 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
2582 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
2583 RHSCst, BO->getName()), I);
2584 return BinaryOperator::create(I.getOpcode(), NewRem,
2585 Constant::getNullValue(UTy));
2589 case Instruction::Add:
2590 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
2591 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2592 if (BO->hasOneUse())
2593 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
2594 ConstantExpr::getSub(CI, BOp1C));
2595 } else if (CI->isNullValue()) {
2596 // Replace ((add A, B) != 0) with (A != -B) if A or B is
2597 // efficiently invertible, or if the add has just this one use.
2598 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
2600 if (Value *NegVal = dyn_castNegVal(BOp1))
2601 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
2602 else if (Value *NegVal = dyn_castNegVal(BOp0))
2603 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
2604 else if (BO->hasOneUse()) {
2605 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
2607 InsertNewInstBefore(Neg, I);
2608 return new SetCondInst(I.getOpcode(), BOp0, Neg);
2612 case Instruction::Xor:
2613 // For the xor case, we can xor two constants together, eliminating
2614 // the explicit xor.
2615 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
2616 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
2617 ConstantExpr::getXor(CI, BOC));
2620 case Instruction::Sub:
2621 // Replace (([sub|xor] A, B) != 0) with (A != B)
2622 if (CI->isNullValue())
2623 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
2627 case Instruction::Or:
2628 // If bits are being or'd in that are not present in the constant we
2629 // are comparing against, then the comparison could never succeed!
2630 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
2631 Constant *NotCI = ConstantExpr::getNot(CI);
2632 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
2633 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
2637 case Instruction::And:
2638 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2639 // If bits are being compared against that are and'd out, then the
2640 // comparison can never succeed!
2641 if (!ConstantExpr::getAnd(CI,
2642 ConstantExpr::getNot(BOC))->isNullValue())
2643 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
2645 // If we have ((X & C) == C), turn it into ((X & C) != 0).
2646 if (CI == BOC && isOneBitSet(CI))
2647 return new SetCondInst(isSetNE ? Instruction::SetEQ :
2648 Instruction::SetNE, Op0,
2649 Constant::getNullValue(CI->getType()));
2651 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
2652 // to be a signed value as appropriate.
2653 if (isSignBit(BOC)) {
2654 Value *X = BO->getOperand(0);
2655 // If 'X' is not signed, insert a cast now...
2656 if (!BOC->getType()->isSigned()) {
2657 const Type *DestTy = BOC->getType()->getSignedVersion();
2658 X = InsertCastBefore(X, DestTy, I);
2660 return new SetCondInst(isSetNE ? Instruction::SetLT :
2661 Instruction::SetGE, X,
2662 Constant::getNullValue(X->getType()));
2665 // ((X & ~7) == 0) --> X < 8
2666 if (CI->isNullValue() && isHighOnes(BOC)) {
2667 Value *X = BO->getOperand(0);
2668 Constant *NegX = ConstantExpr::getNeg(BOC);
2670 // If 'X' is signed, insert a cast now.
2671 if (NegX->getType()->isSigned()) {
2672 const Type *DestTy = NegX->getType()->getUnsignedVersion();
2673 X = InsertCastBefore(X, DestTy, I);
2674 NegX = ConstantExpr::getCast(NegX, DestTy);
2677 return new SetCondInst(isSetNE ? Instruction::SetGE :
2678 Instruction::SetLT, X, NegX);
2685 } else { // Not a SetEQ/SetNE
2686 // If the LHS is a cast from an integral value of the same size,
2687 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
2688 Value *CastOp = Cast->getOperand(0);
2689 const Type *SrcTy = CastOp->getType();
2690 unsigned SrcTySize = SrcTy->getPrimitiveSize();
2691 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
2692 SrcTySize == Cast->getType()->getPrimitiveSize()) {
2693 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
2694 "Source and destination signednesses should differ!");
2695 if (Cast->getType()->isSigned()) {
2696 // If this is a signed comparison, check for comparisons in the
2697 // vicinity of zero.
2698 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
2700 return BinaryOperator::createSetGT(CastOp,
2701 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize*8-1))-1));
2702 else if (I.getOpcode() == Instruction::SetGT &&
2703 cast<ConstantSInt>(CI)->getValue() == -1)
2704 // X > -1 => x < 128
2705 return BinaryOperator::createSetLT(CastOp,
2706 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize*8-1)));
2708 ConstantUInt *CUI = cast<ConstantUInt>(CI);
2709 if (I.getOpcode() == Instruction::SetLT &&
2710 CUI->getValue() == 1ULL << (SrcTySize*8-1))
2711 // X < 128 => X > -1
2712 return BinaryOperator::createSetGT(CastOp,
2713 ConstantSInt::get(SrcTy, -1));
2714 else if (I.getOpcode() == Instruction::SetGT &&
2715 CUI->getValue() == (1ULL << (SrcTySize*8-1))-1)
2717 return BinaryOperator::createSetLT(CastOp,
2718 Constant::getNullValue(SrcTy));
2725 // If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now.
2726 if (User *GEP = dyn_castGetElementPtr(Op0))
2727 if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I))
2729 if (User *GEP = dyn_castGetElementPtr(Op1))
2730 if (Instruction *NI = FoldGEPSetCC(GEP, Op0,
2731 SetCondInst::getSwappedCondition(I.getOpcode()), I))
2734 // Test to see if the operands of the setcc are casted versions of other
2735 // values. If the cast can be stripped off both arguments, we do so now.
2736 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
2737 Value *CastOp0 = CI->getOperand(0);
2738 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
2739 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
2740 (I.getOpcode() == Instruction::SetEQ ||
2741 I.getOpcode() == Instruction::SetNE)) {
2742 // We keep moving the cast from the left operand over to the right
2743 // operand, where it can often be eliminated completely.
2746 // If operand #1 is a cast instruction, see if we can eliminate it as
2748 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
2749 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
2751 Op1 = CI2->getOperand(0);
2753 // If Op1 is a constant, we can fold the cast into the constant.
2754 if (Op1->getType() != Op0->getType())
2755 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
2756 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
2758 // Otherwise, cast the RHS right before the setcc
2759 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
2760 InsertNewInstBefore(cast<Instruction>(Op1), I);
2762 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
2765 // Handle the special case of: setcc (cast bool to X), <cst>
2766 // This comes up when you have code like
2769 // For generality, we handle any zero-extension of any operand comparison
2771 if (ConstantInt *ConstantRHS = dyn_cast<ConstantInt>(Op1)) {
2772 const Type *SrcTy = CastOp0->getType();
2773 const Type *DestTy = Op0->getType();
2774 if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
2775 (SrcTy->isUnsigned() || SrcTy == Type::BoolTy)) {
2776 // Ok, we have an expansion of operand 0 into a new type. Get the
2777 // constant value, masink off bits which are not set in the RHS. These
2778 // could be set if the destination value is signed.
2779 uint64_t ConstVal = ConstantRHS->getRawValue();
2780 ConstVal &= (1ULL << DestTy->getPrimitiveSize()*8)-1;
2782 // If the constant we are comparing it with has high bits set, which
2783 // don't exist in the original value, the values could never be equal,
2784 // because the source would be zero extended.
2786 SrcTy == Type::BoolTy ? 1 : SrcTy->getPrimitiveSize()*8;
2787 bool HasSignBit = ConstVal & (1ULL << (DestTy->getPrimitiveSize()*8-1));
2788 if (ConstVal & ~((1ULL << SrcBits)-1)) {
2789 switch (I.getOpcode()) {
2790 default: assert(0 && "Unknown comparison type!");
2791 case Instruction::SetEQ:
2792 return ReplaceInstUsesWith(I, ConstantBool::False);
2793 case Instruction::SetNE:
2794 return ReplaceInstUsesWith(I, ConstantBool::True);
2795 case Instruction::SetLT:
2796 case Instruction::SetLE:
2797 if (DestTy->isSigned() && HasSignBit)
2798 return ReplaceInstUsesWith(I, ConstantBool::False);
2799 return ReplaceInstUsesWith(I, ConstantBool::True);
2800 case Instruction::SetGT:
2801 case Instruction::SetGE:
2802 if (DestTy->isSigned() && HasSignBit)
2803 return ReplaceInstUsesWith(I, ConstantBool::True);
2804 return ReplaceInstUsesWith(I, ConstantBool::False);
2808 // Otherwise, we can replace the setcc with a setcc of the smaller
2810 Op1 = ConstantExpr::getCast(cast<Constant>(Op1), SrcTy);
2811 return BinaryOperator::create(I.getOpcode(), CastOp0, Op1);
2815 return Changed ? &I : 0;
2818 // visitSetCondInstWithCastAndConstant - this method is part of the
2819 // visitSetCondInst method. It handles the situation where we have:
2820 // (setcc (cast X to larger), CI)
2821 // It tries to remove the cast and even the setcc if the CI value
2822 // and range of the cast allow it.
2824 InstCombiner::visitSetCondInstWithCastAndConstant(BinaryOperator&I,
2827 const Type *SrcTy = LHSI->getOperand(0)->getType();
2828 const Type *DestTy = LHSI->getType();
2829 if (SrcTy->isIntegral() && DestTy->isIntegral()) {
2830 unsigned SrcBits = SrcTy->getPrimitiveSize()*8;
2831 unsigned DestBits = DestTy->getPrimitiveSize()*8;
2832 if (SrcTy == Type::BoolTy)
2834 if (DestTy == Type::BoolTy)
2836 if (SrcBits < DestBits) {
2837 // There are fewer bits in the source of the cast than in the result
2838 // of the cast. Any other case doesn't matter because the constant
2839 // value won't have changed due to sign extension.
2840 Constant *NewCst = ConstantExpr::getCast(CI, SrcTy);
2841 if (ConstantExpr::getCast(NewCst, DestTy) == CI) {
2842 // The constant value operand of the setCC before and after a
2843 // cast to the source type of the cast instruction is the same
2844 // value, so we just replace with the same setcc opcode, but
2845 // using the source value compared to the constant casted to the
2847 if (SrcTy->isSigned() && DestTy->isUnsigned()) {
2848 CastInst* Cst = new CastInst(LHSI->getOperand(0),
2849 SrcTy->getUnsignedVersion(), LHSI->getName());
2850 InsertNewInstBefore(Cst,I);
2851 return new SetCondInst(I.getOpcode(), Cst,
2852 ConstantExpr::getCast(CI, SrcTy->getUnsignedVersion()));
2854 return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),NewCst);
2856 // The constant value before and after a cast to the source type
2857 // is different, so various cases are possible depending on the
2858 // opcode and the signs of the types involved in the cast.
2859 switch (I.getOpcode()) {
2860 case Instruction::SetLT: {
2861 Constant* Max = ConstantIntegral::getMaxValue(SrcTy);
2862 Max = ConstantExpr::getCast(Max, DestTy);
2863 return ReplaceInstUsesWith(I, ConstantExpr::getSetLT(Max, CI));
2865 case Instruction::SetGT: {
2866 Constant* Min = ConstantIntegral::getMinValue(SrcTy);
2867 Min = ConstantExpr::getCast(Min, DestTy);
2868 return ReplaceInstUsesWith(I, ConstantExpr::getSetGT(Min, CI));
2870 case Instruction::SetEQ:
2871 // We're looking for equality, and we know the values are not
2872 // equal so replace with constant False.
2873 return ReplaceInstUsesWith(I, ConstantBool::False);
2874 case Instruction::SetNE:
2875 // We're testing for inequality, and we know the values are not
2876 // equal so replace with constant True.
2877 return ReplaceInstUsesWith(I, ConstantBool::True);
2878 case Instruction::SetLE:
2879 case Instruction::SetGE:
2880 assert(!"SetLE and SetGE should be handled elsewhere");
2882 assert(!"unknown integer comparison");
2890 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
2891 assert(I.getOperand(1)->getType() == Type::UByteTy);
2892 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2893 bool isLeftShift = I.getOpcode() == Instruction::Shl;
2895 // shl X, 0 == X and shr X, 0 == X
2896 // shl 0, X == 0 and shr 0, X == 0
2897 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
2898 Op0 == Constant::getNullValue(Op0->getType()))
2899 return ReplaceInstUsesWith(I, Op0);
2901 if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
2902 if (!isLeftShift && I.getType()->isSigned())
2903 return ReplaceInstUsesWith(I, Op0);
2904 else // undef << X -> 0 AND undef >>u X -> 0
2905 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2907 if (isa<UndefValue>(Op1)) {
2908 if (isLeftShift || I.getType()->isUnsigned())
2909 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2911 return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X
2914 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
2916 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
2917 if (CSI->isAllOnesValue())
2918 return ReplaceInstUsesWith(I, CSI);
2920 // Try to fold constant and into select arguments.
2921 if (isa<Constant>(Op0))
2922 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
2923 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2926 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
2927 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
2928 // of a signed value.
2930 unsigned TypeBits = Op0->getType()->getPrimitiveSize()*8;
2931 if (CUI->getValue() >= TypeBits) {
2932 if (!Op0->getType()->isSigned() || isLeftShift)
2933 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
2935 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
2940 // ((X*C1) << C2) == (X * (C1 << C2))
2941 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
2942 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
2943 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
2944 return BinaryOperator::createMul(BO->getOperand(0),
2945 ConstantExpr::getShl(BOOp, CUI));
2947 // Try to fold constant and into select arguments.
2948 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2949 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2951 if (isa<PHINode>(Op0))
2952 if (Instruction *NV = FoldOpIntoPhi(I))
2955 if (Op0->hasOneUse()) {
2956 // If this is a SHL of a sign-extending cast, see if we can turn the input
2957 // into a zero extending cast (a simple strength reduction).
2958 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
2959 const Type *SrcTy = CI->getOperand(0)->getType();
2960 if (isLeftShift && SrcTy->isInteger() && SrcTy->isSigned() &&
2961 SrcTy->getPrimitiveSize() < CI->getType()->getPrimitiveSize()) {
2962 // We can change it to a zero extension if we are shifting out all of
2963 // the sign extended bits. To check this, form a mask of all of the
2964 // sign extend bits, then shift them left and see if we have anything
2966 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); // 1111
2967 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); // 00001111
2968 Mask = ConstantExpr::getNot(Mask); // 1's in the sign bits: 11110000
2969 if (ConstantExpr::getShl(Mask, CUI)->isNullValue()) {
2970 // If the shift is nuking all of the sign bits, change this to a
2971 // zero extension cast. To do this, cast the cast input to
2972 // unsigned, then to the requested size.
2973 Value *CastOp = CI->getOperand(0);
2975 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
2976 CI->getName()+".uns");
2977 NC = InsertNewInstBefore(NC, I);
2978 // Finally, insert a replacement for CI.
2979 NC = new CastInst(NC, CI->getType(), CI->getName());
2981 NC = InsertNewInstBefore(NC, I);
2982 WorkList.push_back(CI); // Delete CI later.
2983 I.setOperand(0, NC);
2984 return &I; // The SHL operand was modified.
2989 // If the operand is an bitwise operator with a constant RHS, and the
2990 // shift is the only use, we can pull it out of the shift.
2991 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0))
2992 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
2993 bool isValid = true; // Valid only for And, Or, Xor
2994 bool highBitSet = false; // Transform if high bit of constant set?
2996 switch (Op0BO->getOpcode()) {
2997 default: isValid = false; break; // Do not perform transform!
2998 case Instruction::Add:
2999 isValid = isLeftShift;
3001 case Instruction::Or:
3002 case Instruction::Xor:
3005 case Instruction::And:
3010 // If this is a signed shift right, and the high bit is modified
3011 // by the logical operation, do not perform the transformation.
3012 // The highBitSet boolean indicates the value of the high bit of
3013 // the constant which would cause it to be modified for this
3016 if (isValid && !isLeftShift && !I.getType()->isUnsigned()) {
3017 uint64_t Val = Op0C->getRawValue();
3018 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
3022 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI);
3024 Instruction *NewShift =
3025 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI,
3028 InsertNewInstBefore(NewShift, I);
3030 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
3036 // If this is a shift of a shift, see if we can fold the two together...
3037 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
3038 if (ConstantUInt *ShiftAmt1C =
3039 dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) {
3040 unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getValue();
3041 unsigned ShiftAmt2 = (unsigned)CUI->getValue();
3043 // Check for (A << c1) << c2 and (A >> c1) >> c2
3044 if (I.getOpcode() == Op0SI->getOpcode()) {
3045 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
3046 if (Op0->getType()->getPrimitiveSize()*8 < Amt)
3047 Amt = Op0->getType()->getPrimitiveSize()*8;
3048 return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
3049 ConstantUInt::get(Type::UByteTy, Amt));
3052 // Check for (A << c1) >> c2 or visaversa. If we are dealing with
3053 // signed types, we can only support the (A >> c1) << c2 configuration,
3054 // because it can not turn an arbitrary bit of A into a sign bit.
3055 if (I.getType()->isUnsigned() || isLeftShift) {
3056 // Calculate bitmask for what gets shifted off the edge...
3057 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
3059 C = ConstantExpr::getShl(C, ShiftAmt1C);
3061 C = ConstantExpr::getShr(C, ShiftAmt1C);
3064 BinaryOperator::createAnd(Op0SI->getOperand(0), C,
3065 Op0SI->getOperand(0)->getName()+".mask");
3066 InsertNewInstBefore(Mask, I);
3068 // Figure out what flavor of shift we should use...
3069 if (ShiftAmt1 == ShiftAmt2)
3070 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
3071 else if (ShiftAmt1 < ShiftAmt2) {
3072 return new ShiftInst(I.getOpcode(), Mask,
3073 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
3075 return new ShiftInst(Op0SI->getOpcode(), Mask,
3076 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
3092 /// getCastType - In the future, we will split the cast instruction into these
3093 /// various types. Until then, we have to do the analysis here.
3094 static CastType getCastType(const Type *Src, const Type *Dest) {
3095 assert(Src->isIntegral() && Dest->isIntegral() &&
3096 "Only works on integral types!");
3097 unsigned SrcSize = Src->getPrimitiveSize()*8;
3098 if (Src == Type::BoolTy) SrcSize = 1;
3099 unsigned DestSize = Dest->getPrimitiveSize()*8;
3100 if (Dest == Type::BoolTy) DestSize = 1;
3102 if (SrcSize == DestSize) return Noop;
3103 if (SrcSize > DestSize) return Truncate;
3104 if (Src->isSigned()) return Signext;
3109 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
3112 static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
3113 const Type *DstTy, TargetData *TD) {
3115 // It is legal to eliminate the instruction if casting A->B->A if the sizes
3116 // are identical and the bits don't get reinterpreted (for example
3117 // int->float->int would not be allowed).
3118 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
3121 // If we are casting between pointer and integer types, treat pointers as
3122 // integers of the appropriate size for the code below.
3123 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
3124 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
3125 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
3127 // Allow free casting and conversion of sizes as long as the sign doesn't
3129 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
3130 CastType FirstCast = getCastType(SrcTy, MidTy);
3131 CastType SecondCast = getCastType(MidTy, DstTy);
3133 // Capture the effect of these two casts. If the result is a legal cast,
3134 // the CastType is stored here, otherwise a special code is used.
3135 static const unsigned CastResult[] = {
3136 // First cast is noop
3138 // First cast is a truncate
3139 1, 1, 4, 4, // trunc->extend is not safe to eliminate
3140 // First cast is a sign ext
3141 2, 5, 2, 4, // signext->zeroext never ok
3142 // First cast is a zero ext
3146 unsigned Result = CastResult[FirstCast*4+SecondCast];
3148 default: assert(0 && "Illegal table value!");
3153 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
3154 // truncates, we could eliminate more casts.
3155 return (unsigned)getCastType(SrcTy, DstTy) == Result;
3157 return false; // Not possible to eliminate this here.
3159 // Sign or zero extend followed by truncate is always ok if the result
3160 // is a truncate or noop.
3161 CastType ResultCast = getCastType(SrcTy, DstTy);
3162 if (ResultCast == Noop || ResultCast == Truncate)
3164 // Otherwise we are still growing the value, we are only safe if the
3165 // result will match the sign/zeroextendness of the result.
3166 return ResultCast == FirstCast;
3172 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
3173 if (V->getType() == Ty || isa<Constant>(V)) return false;
3174 if (const CastInst *CI = dyn_cast<CastInst>(V))
3175 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
3181 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
3182 /// InsertBefore instruction. This is specialized a bit to avoid inserting
3183 /// casts that are known to not do anything...
3185 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
3186 Instruction *InsertBefore) {
3187 if (V->getType() == DestTy) return V;
3188 if (Constant *C = dyn_cast<Constant>(V))
3189 return ConstantExpr::getCast(C, DestTy);
3191 CastInst *CI = new CastInst(V, DestTy, V->getName());
3192 InsertNewInstBefore(CI, *InsertBefore);
3196 // CastInst simplification
3198 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
3199 Value *Src = CI.getOperand(0);
3201 // If the user is casting a value to the same type, eliminate this cast
3203 if (CI.getType() == Src->getType())
3204 return ReplaceInstUsesWith(CI, Src);
3206 if (isa<UndefValue>(Src)) // cast undef -> undef
3207 return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
3209 // If casting the result of another cast instruction, try to eliminate this
3212 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
3213 Value *A = CSrc->getOperand(0);
3214 if (isEliminableCastOfCast(A->getType(), CSrc->getType(),
3215 CI.getType(), TD)) {
3216 // This instruction now refers directly to the cast's src operand. This
3217 // has a good chance of making CSrc dead.
3218 CI.setOperand(0, CSrc->getOperand(0));
3222 // If this is an A->B->A cast, and we are dealing with integral types, try
3223 // to convert this into a logical 'and' instruction.
3225 if (A->getType()->isInteger() &&
3226 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
3227 CSrc->getType()->isUnsigned() && // B->A cast must zero extend
3228 CSrc->getType()->getPrimitiveSize() < CI.getType()->getPrimitiveSize()&&
3229 A->getType()->getPrimitiveSize() == CI.getType()->getPrimitiveSize()) {
3230 assert(CSrc->getType() != Type::ULongTy &&
3231 "Cannot have type bigger than ulong!");
3232 uint64_t AndValue = (1ULL << CSrc->getType()->getPrimitiveSize()*8)-1;
3233 Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(),
3235 AndOp = ConstantExpr::getCast(AndOp, A->getType());
3236 Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
3237 if (And->getType() != CI.getType()) {
3238 And->setName(CSrc->getName()+".mask");
3239 InsertNewInstBefore(And, CI);
3240 And = new CastInst(And, CI.getType());
3246 // If this is a cast to bool, turn it into the appropriate setne instruction.
3247 if (CI.getType() == Type::BoolTy)
3248 return BinaryOperator::createSetNE(CI.getOperand(0),
3249 Constant::getNullValue(CI.getOperand(0)->getType()));
3251 // If casting the result of a getelementptr instruction with no offset, turn
3252 // this into a cast of the original pointer!
3254 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
3255 bool AllZeroOperands = true;
3256 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
3257 if (!isa<Constant>(GEP->getOperand(i)) ||
3258 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
3259 AllZeroOperands = false;
3262 if (AllZeroOperands) {
3263 CI.setOperand(0, GEP->getOperand(0));
3268 // If we are casting a malloc or alloca to a pointer to a type of the same
3269 // size, rewrite the allocation instruction to allocate the "right" type.
3271 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
3272 if (AI->hasOneUse() && !AI->isArrayAllocation())
3273 if (const PointerType *PTy = dyn_cast<PointerType>(CI.getType())) {
3274 // Get the type really allocated and the type casted to...
3275 const Type *AllocElTy = AI->getAllocatedType();
3276 const Type *CastElTy = PTy->getElementType();
3277 if (AllocElTy->isSized() && CastElTy->isSized()) {
3278 uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
3279 uint64_t CastElTySize = TD->getTypeSize(CastElTy);
3281 // If the allocation is for an even multiple of the cast type size
3282 if (CastElTySize && (AllocElTySize % CastElTySize == 0)) {
3283 Value *Amt = ConstantUInt::get(Type::UIntTy,
3284 AllocElTySize/CastElTySize);
3285 std::string Name = AI->getName(); AI->setName("");
3286 AllocationInst *New;
3287 if (isa<MallocInst>(AI))
3288 New = new MallocInst(CastElTy, Amt, Name);
3290 New = new AllocaInst(CastElTy, Amt, Name);
3291 InsertNewInstBefore(New, *AI);
3292 return ReplaceInstUsesWith(CI, New);
3297 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
3298 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
3300 if (isa<PHINode>(Src))
3301 if (Instruction *NV = FoldOpIntoPhi(CI))
3304 // If the source value is an instruction with only this use, we can attempt to
3305 // propagate the cast into the instruction. Also, only handle integral types
3307 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
3308 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
3309 CI.getType()->isInteger()) { // Don't mess with casts to bool here
3310 const Type *DestTy = CI.getType();
3311 unsigned SrcBitSize = getTypeSizeInBits(Src->getType());
3312 unsigned DestBitSize = getTypeSizeInBits(DestTy);
3314 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
3315 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
3317 switch (SrcI->getOpcode()) {
3318 case Instruction::Add:
3319 case Instruction::Mul:
3320 case Instruction::And:
3321 case Instruction::Or:
3322 case Instruction::Xor:
3323 // If we are discarding information, or just changing the sign, rewrite.
3324 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
3325 // Don't insert two casts if they cannot be eliminated. We allow two
3326 // casts to be inserted if the sizes are the same. This could only be
3327 // converting signedness, which is a noop.
3328 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
3329 !ValueRequiresCast(Op0, DestTy, TD)) {
3330 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
3331 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
3332 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
3333 ->getOpcode(), Op0c, Op1c);
3337 case Instruction::Shl:
3338 // Allow changing the sign of the source operand. Do not allow changing
3339 // the size of the shift, UNLESS the shift amount is a constant. We
3340 // mush not change variable sized shifts to a smaller size, because it
3341 // is undefined to shift more bits out than exist in the value.
3342 if (DestBitSize == SrcBitSize ||
3343 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
3344 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
3345 return new ShiftInst(Instruction::Shl, Op0c, Op1);
3354 /// GetSelectFoldableOperands - We want to turn code that looks like this:
3356 /// %D = select %cond, %C, %A
3358 /// %C = select %cond, %B, 0
3361 /// Assuming that the specified instruction is an operand to the select, return
3362 /// a bitmask indicating which operands of this instruction are foldable if they
3363 /// equal the other incoming value of the select.
3365 static unsigned GetSelectFoldableOperands(Instruction *I) {
3366 switch (I->getOpcode()) {
3367 case Instruction::Add:
3368 case Instruction::Mul:
3369 case Instruction::And:
3370 case Instruction::Or:
3371 case Instruction::Xor:
3372 return 3; // Can fold through either operand.
3373 case Instruction::Sub: // Can only fold on the amount subtracted.
3374 case Instruction::Shl: // Can only fold on the shift amount.
3375 case Instruction::Shr:
3378 return 0; // Cannot fold
3382 /// GetSelectFoldableConstant - For the same transformation as the previous
3383 /// function, return the identity constant that goes into the select.
3384 static Constant *GetSelectFoldableConstant(Instruction *I) {
3385 switch (I->getOpcode()) {
3386 default: assert(0 && "This cannot happen!"); abort();
3387 case Instruction::Add:
3388 case Instruction::Sub:
3389 case Instruction::Or:
3390 case Instruction::Xor:
3391 return Constant::getNullValue(I->getType());
3392 case Instruction::Shl:
3393 case Instruction::Shr:
3394 return Constant::getNullValue(Type::UByteTy);
3395 case Instruction::And:
3396 return ConstantInt::getAllOnesValue(I->getType());
3397 case Instruction::Mul:
3398 return ConstantInt::get(I->getType(), 1);
3402 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
3403 Value *CondVal = SI.getCondition();
3404 Value *TrueVal = SI.getTrueValue();
3405 Value *FalseVal = SI.getFalseValue();
3407 // select true, X, Y -> X
3408 // select false, X, Y -> Y
3409 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
3410 if (C == ConstantBool::True)
3411 return ReplaceInstUsesWith(SI, TrueVal);
3413 assert(C == ConstantBool::False);
3414 return ReplaceInstUsesWith(SI, FalseVal);
3417 // select C, X, X -> X
3418 if (TrueVal == FalseVal)
3419 return ReplaceInstUsesWith(SI, TrueVal);
3421 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
3422 return ReplaceInstUsesWith(SI, FalseVal);
3423 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
3424 return ReplaceInstUsesWith(SI, TrueVal);
3425 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
3426 if (isa<Constant>(TrueVal))
3427 return ReplaceInstUsesWith(SI, TrueVal);
3429 return ReplaceInstUsesWith(SI, FalseVal);
3432 if (SI.getType() == Type::BoolTy)
3433 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
3434 if (C == ConstantBool::True) {
3435 // Change: A = select B, true, C --> A = or B, C
3436 return BinaryOperator::createOr(CondVal, FalseVal);
3438 // Change: A = select B, false, C --> A = and !B, C
3440 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
3441 "not."+CondVal->getName()), SI);
3442 return BinaryOperator::createAnd(NotCond, FalseVal);
3444 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
3445 if (C == ConstantBool::False) {
3446 // Change: A = select B, C, false --> A = and B, C
3447 return BinaryOperator::createAnd(CondVal, TrueVal);
3449 // Change: A = select B, C, true --> A = or !B, C
3451 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
3452 "not."+CondVal->getName()), SI);
3453 return BinaryOperator::createOr(NotCond, TrueVal);
3457 // Selecting between two integer constants?
3458 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
3459 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
3460 // select C, 1, 0 -> cast C to int
3461 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
3462 return new CastInst(CondVal, SI.getType());
3463 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
3464 // select C, 0, 1 -> cast !C to int
3466 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
3467 "not."+CondVal->getName()), SI);
3468 return new CastInst(NotCond, SI.getType());
3471 // If one of the constants is zero (we know they can't both be) and we
3472 // have a setcc instruction with zero, and we have an 'and' with the
3473 // non-constant value, eliminate this whole mess. This corresponds to
3474 // cases like this: ((X & 27) ? 27 : 0)
3475 if (TrueValC->isNullValue() || FalseValC->isNullValue())
3476 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
3477 if ((IC->getOpcode() == Instruction::SetEQ ||
3478 IC->getOpcode() == Instruction::SetNE) &&
3479 isa<ConstantInt>(IC->getOperand(1)) &&
3480 cast<Constant>(IC->getOperand(1))->isNullValue())
3481 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
3482 if (ICA->getOpcode() == Instruction::And &&
3483 isa<ConstantInt>(ICA->getOperand(1)) &&
3484 (ICA->getOperand(1) == TrueValC ||
3485 ICA->getOperand(1) == FalseValC) &&
3486 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
3487 // Okay, now we know that everything is set up, we just don't
3488 // know whether we have a setne or seteq and whether the true or
3489 // false val is the zero.
3490 bool ShouldNotVal = !TrueValC->isNullValue();
3491 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
3494 V = InsertNewInstBefore(BinaryOperator::create(
3495 Instruction::Xor, V, ICA->getOperand(1)), SI);
3496 return ReplaceInstUsesWith(SI, V);
3500 // See if we are selecting two values based on a comparison of the two values.
3501 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
3502 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
3503 // Transform (X == Y) ? X : Y -> Y
3504 if (SCI->getOpcode() == Instruction::SetEQ)
3505 return ReplaceInstUsesWith(SI, FalseVal);
3506 // Transform (X != Y) ? X : Y -> X
3507 if (SCI->getOpcode() == Instruction::SetNE)
3508 return ReplaceInstUsesWith(SI, TrueVal);
3509 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
3511 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
3512 // Transform (X == Y) ? Y : X -> X
3513 if (SCI->getOpcode() == Instruction::SetEQ)
3514 return ReplaceInstUsesWith(SI, FalseVal);
3515 // Transform (X != Y) ? Y : X -> Y
3516 if (SCI->getOpcode() == Instruction::SetNE)
3517 return ReplaceInstUsesWith(SI, TrueVal);
3518 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
3522 // See if we can fold the select into one of our operands.
3523 if (SI.getType()->isInteger()) {
3524 // See the comment above GetSelectFoldableOperands for a description of the
3525 // transformation we are doing here.
3526 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
3527 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
3528 !isa<Constant>(FalseVal))
3529 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
3530 unsigned OpToFold = 0;
3531 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
3533 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
3538 Constant *C = GetSelectFoldableConstant(TVI);
3539 std::string Name = TVI->getName(); TVI->setName("");
3540 Instruction *NewSel =
3541 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
3543 InsertNewInstBefore(NewSel, SI);
3544 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
3545 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
3546 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
3547 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
3549 assert(0 && "Unknown instruction!!");
3554 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
3555 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
3556 !isa<Constant>(TrueVal))
3557 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
3558 unsigned OpToFold = 0;
3559 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
3561 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
3566 Constant *C = GetSelectFoldableConstant(FVI);
3567 std::string Name = FVI->getName(); FVI->setName("");
3568 Instruction *NewSel =
3569 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
3571 InsertNewInstBefore(NewSel, SI);
3572 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
3573 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
3574 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
3575 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
3577 assert(0 && "Unknown instruction!!");
3586 // CallInst simplification
3588 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
3589 // Intrinsics cannot occur in an invoke, so handle them here instead of in
3591 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(&CI)) {
3592 bool Changed = false;
3594 // memmove/cpy/set of zero bytes is a noop.
3595 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
3596 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
3598 // FIXME: Increase alignment here.
3600 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
3601 if (CI->getRawValue() == 1) {
3602 // Replace the instruction with just byte operations. We would
3603 // transform other cases to loads/stores, but we don't know if
3604 // alignment is sufficient.
3608 // If we have a memmove and the source operation is a constant global,
3609 // then the source and dest pointers can't alias, so we can change this
3610 // into a call to memcpy.
3611 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI))
3612 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
3613 if (GVSrc->isConstant()) {
3614 Module *M = CI.getParent()->getParent()->getParent();
3615 Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
3616 CI.getCalledFunction()->getFunctionType());
3617 CI.setOperand(0, MemCpy);
3621 if (Changed) return &CI;
3622 } else if (DbgStopPointInst *SPI = dyn_cast<DbgStopPointInst>(&CI)) {
3623 // If this stoppoint is at the same source location as the previous
3624 // stoppoint in the chain, it is not needed.
3625 if (DbgStopPointInst *PrevSPI =
3626 dyn_cast<DbgStopPointInst>(SPI->getChain()))
3627 if (SPI->getLineNo() == PrevSPI->getLineNo() &&
3628 SPI->getColNo() == PrevSPI->getColNo()) {
3629 SPI->replaceAllUsesWith(PrevSPI);
3630 return EraseInstFromFunction(CI);
3634 return visitCallSite(&CI);
3637 // InvokeInst simplification
3639 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
3640 return visitCallSite(&II);
3643 // visitCallSite - Improvements for call and invoke instructions.
3645 Instruction *InstCombiner::visitCallSite(CallSite CS) {
3646 bool Changed = false;
3648 // If the callee is a constexpr cast of a function, attempt to move the cast
3649 // to the arguments of the call/invoke.
3650 if (transformConstExprCastCall(CS)) return 0;
3652 Value *Callee = CS.getCalledValue();
3654 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
3655 // This instruction is not reachable, just remove it. We insert a store to
3656 // undef so that we know that this code is not reachable, despite the fact
3657 // that we can't modify the CFG here.
3658 new StoreInst(ConstantBool::True,
3659 UndefValue::get(PointerType::get(Type::BoolTy)),
3660 CS.getInstruction());
3662 if (!CS.getInstruction()->use_empty())
3663 CS.getInstruction()->
3664 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
3666 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
3667 // Don't break the CFG, insert a dummy cond branch.
3668 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
3669 ConstantBool::True, II);
3671 return EraseInstFromFunction(*CS.getInstruction());
3674 const PointerType *PTy = cast<PointerType>(Callee->getType());
3675 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
3676 if (FTy->isVarArg()) {
3677 // See if we can optimize any arguments passed through the varargs area of
3679 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
3680 E = CS.arg_end(); I != E; ++I)
3681 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
3682 // If this cast does not effect the value passed through the varargs
3683 // area, we can eliminate the use of the cast.
3684 Value *Op = CI->getOperand(0);
3685 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
3692 return Changed ? CS.getInstruction() : 0;
3695 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
3696 // attempt to move the cast to the arguments of the call/invoke.
3698 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
3699 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
3700 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
3701 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
3703 Function *Callee = cast<Function>(CE->getOperand(0));
3704 Instruction *Caller = CS.getInstruction();
3706 // Okay, this is a cast from a function to a different type. Unless doing so
3707 // would cause a type conversion of one of our arguments, change this call to
3708 // be a direct call with arguments casted to the appropriate types.
3710 const FunctionType *FT = Callee->getFunctionType();
3711 const Type *OldRetTy = Caller->getType();
3713 // Check to see if we are changing the return type...
3714 if (OldRetTy != FT->getReturnType()) {
3715 if (Callee->isExternal() &&
3716 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
3717 !Caller->use_empty())
3718 return false; // Cannot transform this return value...
3720 // If the callsite is an invoke instruction, and the return value is used by
3721 // a PHI node in a successor, we cannot change the return type of the call
3722 // because there is no place to put the cast instruction (without breaking
3723 // the critical edge). Bail out in this case.
3724 if (!Caller->use_empty())
3725 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
3726 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
3728 if (PHINode *PN = dyn_cast<PHINode>(*UI))
3729 if (PN->getParent() == II->getNormalDest() ||
3730 PN->getParent() == II->getUnwindDest())
3734 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
3735 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
3737 CallSite::arg_iterator AI = CS.arg_begin();
3738 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
3739 const Type *ParamTy = FT->getParamType(i);
3740 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
3741 if (Callee->isExternal() && !isConvertible) return false;
3744 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
3745 Callee->isExternal())
3746 return false; // Do not delete arguments unless we have a function body...
3748 // Okay, we decided that this is a safe thing to do: go ahead and start
3749 // inserting cast instructions as necessary...
3750 std::vector<Value*> Args;
3751 Args.reserve(NumActualArgs);
3753 AI = CS.arg_begin();
3754 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
3755 const Type *ParamTy = FT->getParamType(i);
3756 if ((*AI)->getType() == ParamTy) {
3757 Args.push_back(*AI);
3759 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
3764 // If the function takes more arguments than the call was taking, add them
3766 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
3767 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
3769 // If we are removing arguments to the function, emit an obnoxious warning...
3770 if (FT->getNumParams() < NumActualArgs)
3771 if (!FT->isVarArg()) {
3772 std::cerr << "WARNING: While resolving call to function '"
3773 << Callee->getName() << "' arguments were dropped!\n";
3775 // Add all of the arguments in their promoted form to the arg list...
3776 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
3777 const Type *PTy = getPromotedType((*AI)->getType());
3778 if (PTy != (*AI)->getType()) {
3779 // Must promote to pass through va_arg area!
3780 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
3781 InsertNewInstBefore(Cast, *Caller);
3782 Args.push_back(Cast);
3784 Args.push_back(*AI);
3789 if (FT->getReturnType() == Type::VoidTy)
3790 Caller->setName(""); // Void type should not have a name...
3793 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
3794 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
3795 Args, Caller->getName(), Caller);
3797 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
3800 // Insert a cast of the return type as necessary...
3802 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
3803 if (NV->getType() != Type::VoidTy) {
3804 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
3806 // If this is an invoke instruction, we should insert it after the first
3807 // non-phi, instruction in the normal successor block.
3808 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
3809 BasicBlock::iterator I = II->getNormalDest()->begin();
3810 while (isa<PHINode>(I)) ++I;
3811 InsertNewInstBefore(NC, *I);
3813 // Otherwise, it's a call, just insert cast right after the call instr
3814 InsertNewInstBefore(NC, *Caller);
3816 AddUsersToWorkList(*Caller);
3818 NV = UndefValue::get(Caller->getType());
3822 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
3823 Caller->replaceAllUsesWith(NV);
3824 Caller->getParent()->getInstList().erase(Caller);
3825 removeFromWorkList(Caller);
3830 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
3831 // operator and they all are only used by the PHI, PHI together their
3832 // inputs, and do the operation once, to the result of the PHI.
3833 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
3834 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
3836 // Scan the instruction, looking for input operations that can be folded away.
3837 // If all input operands to the phi are the same instruction (e.g. a cast from
3838 // the same type or "+42") we can pull the operation through the PHI, reducing
3839 // code size and simplifying code.
3840 Constant *ConstantOp = 0;
3841 const Type *CastSrcTy = 0;
3842 if (isa<CastInst>(FirstInst)) {
3843 CastSrcTy = FirstInst->getOperand(0)->getType();
3844 } else if (isa<BinaryOperator>(FirstInst) || isa<ShiftInst>(FirstInst)) {
3845 // Can fold binop or shift if the RHS is a constant.
3846 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
3847 if (ConstantOp == 0) return 0;
3849 return 0; // Cannot fold this operation.
3852 // Check to see if all arguments are the same operation.
3853 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
3854 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
3855 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
3856 if (!I->hasOneUse() || I->getOpcode() != FirstInst->getOpcode())
3859 if (I->getOperand(0)->getType() != CastSrcTy)
3860 return 0; // Cast operation must match.
3861 } else if (I->getOperand(1) != ConstantOp) {
3866 // Okay, they are all the same operation. Create a new PHI node of the
3867 // correct type, and PHI together all of the LHS's of the instructions.
3868 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
3869 PN.getName()+".in");
3870 NewPN->op_reserve(PN.getNumOperands());
3872 Value *InVal = FirstInst->getOperand(0);
3873 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
3875 // Add all operands to the new PHI.
3876 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
3877 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
3878 if (NewInVal != InVal)
3880 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
3885 // The new PHI unions all of the same values together. This is really
3886 // common, so we handle it intelligently here for compile-time speed.
3890 InsertNewInstBefore(NewPN, PN);
3894 // Insert and return the new operation.
3895 if (isa<CastInst>(FirstInst))
3896 return new CastInst(PhiVal, PN.getType());
3897 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
3898 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
3900 return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(),
3901 PhiVal, ConstantOp);
3904 // PHINode simplification
3906 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
3907 if (Value *V = hasConstantValue(&PN)) {
3908 // If V is an instruction, we have to be certain that it dominates PN.
3909 // However, because we don't have dom info, we can't do a perfect job.
3910 if (Instruction *I = dyn_cast<Instruction>(V)) {
3911 // We know that the instruction dominates the PHI if there are no undef
3912 // values coming in.
3913 if (I->getParent() != &I->getParent()->getParent()->front() ||
3915 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
3916 if (isa<UndefValue>(PN.getIncomingValue(i))) {
3923 return ReplaceInstUsesWith(PN, V);
3926 // If the only user of this instruction is a cast instruction, and all of the
3927 // incoming values are constants, change this PHI to merge together the casted
3930 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
3931 if (CI->getType() != PN.getType()) { // noop casts will be folded
3932 bool AllConstant = true;
3933 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
3934 if (!isa<Constant>(PN.getIncomingValue(i))) {
3935 AllConstant = false;
3939 // Make a new PHI with all casted values.
3940 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
3941 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
3942 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
3943 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
3944 PN.getIncomingBlock(i));
3947 // Update the cast instruction.
3948 CI->setOperand(0, New);
3949 WorkList.push_back(CI); // revisit the cast instruction to fold.
3950 WorkList.push_back(New); // Make sure to revisit the new Phi
3951 return &PN; // PN is now dead!
3955 // If all PHI operands are the same operation, pull them through the PHI,
3956 // reducing code size.
3957 if (isa<Instruction>(PN.getIncomingValue(0)) &&
3958 PN.getIncomingValue(0)->hasOneUse())
3959 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
3966 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
3967 Instruction *InsertPoint,
3969 unsigned PS = IC->getTargetData().getPointerSize();
3970 const Type *VTy = V->getType();
3971 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
3972 // We must insert a cast to ensure we sign-extend.
3973 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
3974 V->getName()), *InsertPoint);
3975 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
3980 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
3981 Value *PtrOp = GEP.getOperand(0);
3982 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
3983 // If so, eliminate the noop.
3984 if (GEP.getNumOperands() == 1)
3985 return ReplaceInstUsesWith(GEP, PtrOp);
3987 if (isa<UndefValue>(GEP.getOperand(0)))
3988 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
3990 bool HasZeroPointerIndex = false;
3991 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
3992 HasZeroPointerIndex = C->isNullValue();
3994 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
3995 return ReplaceInstUsesWith(GEP, PtrOp);
3997 // Eliminate unneeded casts for indices.
3998 bool MadeChange = false;
3999 gep_type_iterator GTI = gep_type_begin(GEP);
4000 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
4001 if (isa<SequentialType>(*GTI)) {
4002 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
4003 Value *Src = CI->getOperand(0);
4004 const Type *SrcTy = Src->getType();
4005 const Type *DestTy = CI->getType();
4006 if (Src->getType()->isInteger()) {
4007 if (SrcTy->getPrimitiveSize() == DestTy->getPrimitiveSize()) {
4008 // We can always eliminate a cast from ulong or long to the other.
4009 // We can always eliminate a cast from uint to int or the other on
4010 // 32-bit pointer platforms.
4011 if (DestTy->getPrimitiveSize() >= TD->getPointerSize()) {
4013 GEP.setOperand(i, Src);
4015 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
4016 SrcTy->getPrimitiveSize() == 4) {
4017 // We can always eliminate a cast from int to [u]long. We can
4018 // eliminate a cast from uint to [u]long iff the target is a 32-bit
4020 if (SrcTy->isSigned() ||
4021 SrcTy->getPrimitiveSize() >= TD->getPointerSize()) {
4023 GEP.setOperand(i, Src);
4028 // If we are using a wider index than needed for this platform, shrink it
4029 // to what we need. If the incoming value needs a cast instruction,
4030 // insert it. This explicit cast can make subsequent optimizations more
4032 Value *Op = GEP.getOperand(i);
4033 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
4034 if (Constant *C = dyn_cast<Constant>(Op)) {
4035 GEP.setOperand(i, ConstantExpr::getCast(C,
4036 TD->getIntPtrType()->getSignedVersion()));
4039 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
4040 Op->getName()), GEP);
4041 GEP.setOperand(i, Op);
4045 // If this is a constant idx, make sure to canonicalize it to be a signed
4046 // operand, otherwise CSE and other optimizations are pessimized.
4047 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
4048 GEP.setOperand(i, ConstantExpr::getCast(CUI,
4049 CUI->getType()->getSignedVersion()));
4053 if (MadeChange) return &GEP;
4055 // Combine Indices - If the source pointer to this getelementptr instruction
4056 // is a getelementptr instruction, combine the indices of the two
4057 // getelementptr instructions into a single instruction.
4059 std::vector<Value*> SrcGEPOperands;
4060 if (User *Src = dyn_castGetElementPtr(PtrOp))
4061 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
4063 if (!SrcGEPOperands.empty()) {
4064 // Note that if our source is a gep chain itself that we wait for that
4065 // chain to be resolved before we perform this transformation. This
4066 // avoids us creating a TON of code in some cases.
4068 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
4069 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
4070 return 0; // Wait until our source is folded to completion.
4072 std::vector<Value *> Indices;
4074 // Find out whether the last index in the source GEP is a sequential idx.
4075 bool EndsWithSequential = false;
4076 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
4077 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
4078 EndsWithSequential = !isa<StructType>(*I);
4080 // Can we combine the two pointer arithmetics offsets?
4081 if (EndsWithSequential) {
4082 // Replace: gep (gep %P, long B), long A, ...
4083 // With: T = long A+B; gep %P, T, ...
4085 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
4086 if (SO1 == Constant::getNullValue(SO1->getType())) {
4088 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
4091 // If they aren't the same type, convert both to an integer of the
4092 // target's pointer size.
4093 if (SO1->getType() != GO1->getType()) {
4094 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
4095 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
4096 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
4097 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
4099 unsigned PS = TD->getPointerSize();
4100 if (SO1->getType()->getPrimitiveSize() == PS) {
4101 // Convert GO1 to SO1's type.
4102 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
4104 } else if (GO1->getType()->getPrimitiveSize() == PS) {
4105 // Convert SO1 to GO1's type.
4106 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
4108 const Type *PT = TD->getIntPtrType();
4109 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
4110 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
4114 if (isa<Constant>(SO1) && isa<Constant>(GO1))
4115 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
4117 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
4118 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
4122 // Recycle the GEP we already have if possible.
4123 if (SrcGEPOperands.size() == 2) {
4124 GEP.setOperand(0, SrcGEPOperands[0]);
4125 GEP.setOperand(1, Sum);
4128 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
4129 SrcGEPOperands.end()-1);
4130 Indices.push_back(Sum);
4131 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
4133 } else if (isa<Constant>(*GEP.idx_begin()) &&
4134 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
4135 SrcGEPOperands.size() != 1) {
4136 // Otherwise we can do the fold if the first index of the GEP is a zero
4137 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
4138 SrcGEPOperands.end());
4139 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
4142 if (!Indices.empty())
4143 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
4145 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
4146 // GEP of global variable. If all of the indices for this GEP are
4147 // constants, we can promote this to a constexpr instead of an instruction.
4149 // Scan for nonconstants...
4150 std::vector<Constant*> Indices;
4151 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
4152 for (; I != E && isa<Constant>(*I); ++I)
4153 Indices.push_back(cast<Constant>(*I));
4155 if (I == E) { // If they are all constants...
4156 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
4158 // Replace all uses of the GEP with the new constexpr...
4159 return ReplaceInstUsesWith(GEP, CE);
4161 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(PtrOp)) {
4162 if (CE->getOpcode() == Instruction::Cast) {
4163 if (HasZeroPointerIndex) {
4164 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
4165 // into : GEP [10 x ubyte]* X, long 0, ...
4167 // This occurs when the program declares an array extern like "int X[];"
4169 Constant *X = CE->getOperand(0);
4170 const PointerType *CPTy = cast<PointerType>(CE->getType());
4171 if (const PointerType *XTy = dyn_cast<PointerType>(X->getType()))
4172 if (const ArrayType *XATy =
4173 dyn_cast<ArrayType>(XTy->getElementType()))
4174 if (const ArrayType *CATy =
4175 dyn_cast<ArrayType>(CPTy->getElementType()))
4176 if (CATy->getElementType() == XATy->getElementType()) {
4177 // At this point, we know that the cast source type is a pointer
4178 // to an array of the same type as the destination pointer
4179 // array. Because the array type is never stepped over (there
4180 // is a leading zero) we can fold the cast into this GEP.
4181 GEP.setOperand(0, X);
4184 } else if (GEP.getNumOperands() == 2 &&
4185 isa<PointerType>(CE->getOperand(0)->getType())) {
4186 // Transform things like:
4187 // %t = getelementptr ubyte* cast ([2 x sbyte]* %str to ubyte*), uint %V
4188 // into: %t1 = getelementptr [2 x sbyte*]* %str, int 0, uint %V; cast
4189 Constant *X = CE->getOperand(0);
4190 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
4191 const Type *ResElTy =cast<PointerType>(CE->getType())->getElementType();
4192 if (isa<ArrayType>(SrcElTy) &&
4193 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
4194 TD->getTypeSize(ResElTy)) {
4195 Value *V = InsertNewInstBefore(
4196 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
4197 GEP.getOperand(1), GEP.getName()), GEP);
4198 return new CastInst(V, GEP.getType());
4207 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
4208 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
4209 if (AI.isArrayAllocation()) // Check C != 1
4210 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
4211 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
4212 AllocationInst *New = 0;
4214 // Create and insert the replacement instruction...
4215 if (isa<MallocInst>(AI))
4216 New = new MallocInst(NewTy, 0, AI.getName());
4218 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
4219 New = new AllocaInst(NewTy, 0, AI.getName());
4222 InsertNewInstBefore(New, AI);
4224 // Scan to the end of the allocation instructions, to skip over a block of
4225 // allocas if possible...
4227 BasicBlock::iterator It = New;
4228 while (isa<AllocationInst>(*It)) ++It;
4230 // Now that I is pointing to the first non-allocation-inst in the block,
4231 // insert our getelementptr instruction...
4233 std::vector<Value*> Idx(2, Constant::getNullValue(Type::IntTy));
4234 Value *V = new GetElementPtrInst(New, Idx, New->getName()+".sub", It);
4236 // Now make everything use the getelementptr instead of the original
4238 return ReplaceInstUsesWith(AI, V);
4239 } else if (isa<UndefValue>(AI.getArraySize())) {
4240 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
4243 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
4244 // Note that we only do this for alloca's, because malloc should allocate and
4245 // return a unique pointer, even for a zero byte allocation.
4246 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
4247 TD->getTypeSize(AI.getAllocatedType()) == 0)
4248 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
4253 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
4254 Value *Op = FI.getOperand(0);
4256 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
4257 if (CastInst *CI = dyn_cast<CastInst>(Op))
4258 if (isa<PointerType>(CI->getOperand(0)->getType())) {
4259 FI.setOperand(0, CI->getOperand(0));
4263 // free undef -> unreachable.
4264 if (isa<UndefValue>(Op)) {
4265 // Insert a new store to null because we cannot modify the CFG here.
4266 new StoreInst(ConstantBool::True,
4267 UndefValue::get(PointerType::get(Type::BoolTy)), &FI);
4268 return EraseInstFromFunction(FI);
4271 // If we have 'free null' delete the instruction. This can happen in stl code
4272 // when lots of inlining happens.
4273 if (isa<ConstantPointerNull>(Op))
4274 return EraseInstFromFunction(FI);
4280 /// GetGEPGlobalInitializer - Given a constant, and a getelementptr
4281 /// constantexpr, return the constant value being addressed by the constant
4282 /// expression, or null if something is funny.
4284 static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
4285 if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
4286 return 0; // Do not allow stepping over the value!
4288 // Loop over all of the operands, tracking down which value we are
4290 gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
4291 for (++I; I != E; ++I)
4292 if (const StructType *STy = dyn_cast<StructType>(*I)) {
4293 ConstantUInt *CU = cast<ConstantUInt>(I.getOperand());
4294 assert(CU->getValue() < STy->getNumElements() &&
4295 "Struct index out of range!");
4296 unsigned El = (unsigned)CU->getValue();
4297 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
4298 C = CS->getOperand(El);
4299 } else if (isa<ConstantAggregateZero>(C)) {
4300 C = Constant::getNullValue(STy->getElementType(El));
4301 } else if (isa<UndefValue>(C)) {
4302 C = UndefValue::get(STy->getElementType(El));
4306 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
4307 const ArrayType *ATy = cast<ArrayType>(*I);
4308 if ((uint64_t)CI->getRawValue() >= ATy->getNumElements()) return 0;
4309 if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
4310 C = CA->getOperand((unsigned)CI->getRawValue());
4311 else if (isa<ConstantAggregateZero>(C))
4312 C = Constant::getNullValue(ATy->getElementType());
4313 else if (isa<UndefValue>(C))
4314 C = UndefValue::get(ATy->getElementType());
4323 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
4324 User *CI = cast<User>(LI.getOperand(0));
4326 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
4327 if (const PointerType *SrcTy =
4328 dyn_cast<PointerType>(CI->getOperand(0)->getType())) {
4329 const Type *SrcPTy = SrcTy->getElementType();
4330 if (SrcPTy->isSized() && DestPTy->isSized() &&
4331 IC.getTargetData().getTypeSize(SrcPTy) ==
4332 IC.getTargetData().getTypeSize(DestPTy) &&
4333 (SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
4334 (DestPTy->isInteger() || isa<PointerType>(DestPTy))) {
4335 // Okay, we are casting from one integer or pointer type to another of
4336 // the same size. Instead of casting the pointer before the load, cast
4337 // the result of the loaded value.
4338 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CI->getOperand(0),
4340 LI.isVolatile()),LI);
4341 // Now cast the result of the load.
4342 return new CastInst(NewLoad, LI.getType());
4348 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
4349 /// from this value cannot trap. If it is not obviously safe to load from the
4350 /// specified pointer, we do a quick local scan of the basic block containing
4351 /// ScanFrom, to determine if the address is already accessed.
4352 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
4353 // If it is an alloca or global variable, it is always safe to load from.
4354 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
4356 // Otherwise, be a little bit agressive by scanning the local block where we
4357 // want to check to see if the pointer is already being loaded or stored
4358 // from/to. If so, the previous load or store would have already trapped,
4359 // so there is no harm doing an extra load (also, CSE will later eliminate
4360 // the load entirely).
4361 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
4366 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
4367 if (LI->getOperand(0) == V) return true;
4368 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
4369 if (SI->getOperand(1) == V) return true;
4375 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
4376 Value *Op = LI.getOperand(0);
4378 if (Constant *C = dyn_cast<Constant>(Op)) {
4379 if ((C->isNullValue() || isa<UndefValue>(C)) &&
4380 !LI.isVolatile()) { // load null/undef -> undef
4381 // Insert a new store to null instruction before the load to indicate that
4382 // this code is not reachable. We do this instead of inserting an
4383 // unreachable instruction directly because we cannot modify the CFG.
4384 new StoreInst(UndefValue::get(LI.getType()), C, &LI);
4385 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
4388 // Instcombine load (constant global) into the value loaded.
4389 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
4390 if (GV->isConstant() && !GV->isExternal())
4391 return ReplaceInstUsesWith(LI, GV->getInitializer());
4393 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
4394 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
4395 if (CE->getOpcode() == Instruction::GetElementPtr) {
4396 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
4397 if (GV->isConstant() && !GV->isExternal())
4398 if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
4399 return ReplaceInstUsesWith(LI, V);
4400 } else if (CE->getOpcode() == Instruction::Cast) {
4401 if (Instruction *Res = InstCombineLoadCast(*this, LI))
4406 // load (cast X) --> cast (load X) iff safe
4407 if (CastInst *CI = dyn_cast<CastInst>(Op))
4408 if (Instruction *Res = InstCombineLoadCast(*this, LI))
4411 if (!LI.isVolatile() && Op->hasOneUse()) {
4412 // Change select and PHI nodes to select values instead of addresses: this
4413 // helps alias analysis out a lot, allows many others simplifications, and
4414 // exposes redundancy in the code.
4416 // Note that we cannot do the transformation unless we know that the
4417 // introduced loads cannot trap! Something like this is valid as long as
4418 // the condition is always false: load (select bool %C, int* null, int* %G),
4419 // but it would not be valid if we transformed it to load from null
4422 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
4423 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
4424 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
4425 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
4426 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
4427 SI->getOperand(1)->getName()+".val"), LI);
4428 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
4429 SI->getOperand(2)->getName()+".val"), LI);
4430 return new SelectInst(SI->getCondition(), V1, V2);
4433 // load (select (cond, null, P)) -> load P
4434 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
4435 if (C->isNullValue()) {
4436 LI.setOperand(0, SI->getOperand(2));
4440 // load (select (cond, P, null)) -> load P
4441 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
4442 if (C->isNullValue()) {
4443 LI.setOperand(0, SI->getOperand(1));
4447 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
4448 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
4449 bool Safe = PN->getParent() == LI.getParent();
4451 // Scan all of the instructions between the PHI and the load to make
4452 // sure there are no instructions that might possibly alter the value
4453 // loaded from the PHI.
4455 BasicBlock::iterator I = &LI;
4456 for (--I; !isa<PHINode>(I); --I)
4457 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
4463 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
4464 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
4465 PN->getIncomingBlock(i)->getTerminator()))
4470 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
4471 InsertNewInstBefore(NewPN, *PN);
4472 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
4474 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
4475 BasicBlock *BB = PN->getIncomingBlock(i);
4476 Value *&TheLoad = LoadMap[BB];
4478 Value *InVal = PN->getIncomingValue(i);
4479 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
4480 InVal->getName()+".val"),
4481 *BB->getTerminator());
4483 NewPN->addIncoming(TheLoad, BB);
4485 return ReplaceInstUsesWith(LI, NewPN);
4492 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
4493 // Change br (not X), label True, label False to: br X, label False, True
4495 BasicBlock *TrueDest;
4496 BasicBlock *FalseDest;
4497 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
4498 !isa<Constant>(X)) {
4499 // Swap Destinations and condition...
4501 BI.setSuccessor(0, FalseDest);
4502 BI.setSuccessor(1, TrueDest);
4506 // Cannonicalize setne -> seteq
4507 Instruction::BinaryOps Op; Value *Y;
4508 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
4509 TrueDest, FalseDest)))
4510 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
4511 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
4512 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
4513 std::string Name = I->getName(); I->setName("");
4514 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
4515 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
4516 // Swap Destinations and condition...
4517 BI.setCondition(NewSCC);
4518 BI.setSuccessor(0, FalseDest);
4519 BI.setSuccessor(1, TrueDest);
4520 removeFromWorkList(I);
4521 I->getParent()->getInstList().erase(I);
4522 WorkList.push_back(cast<Instruction>(NewSCC));
4529 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
4530 Value *Cond = SI.getCondition();
4531 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
4532 if (I->getOpcode() == Instruction::Add)
4533 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
4534 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
4535 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
4536 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
4538 SI.setOperand(0, I->getOperand(0));
4539 WorkList.push_back(I);
4547 void InstCombiner::removeFromWorkList(Instruction *I) {
4548 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
4553 /// TryToSinkInstruction - Try to move the specified instruction from its
4554 /// current block into the beginning of DestBlock, which can only happen if it's
4555 /// safe to move the instruction past all of the instructions between it and the
4556 /// end of its block.
4557 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
4558 assert(I->hasOneUse() && "Invariants didn't hold!");
4560 // Cannot move control-flow-involving instructions.
4561 if (isa<PHINode>(I) || isa<InvokeInst>(I) || isa<CallInst>(I)) return false;
4563 // Do not sink alloca instructions out of the entry block.
4564 if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front())
4567 // We can only sink load instructions if there is nothing between the load and
4568 // the end of block that could change the value.
4569 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
4570 if (LI->isVolatile()) return false; // Don't sink volatile loads.
4572 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
4574 if (Scan->mayWriteToMemory())
4578 BasicBlock::iterator InsertPos = DestBlock->begin();
4579 while (isa<PHINode>(InsertPos)) ++InsertPos;
4581 BasicBlock *SrcBlock = I->getParent();
4582 DestBlock->getInstList().splice(InsertPos, SrcBlock->getInstList(), I);
4587 bool InstCombiner::runOnFunction(Function &F) {
4588 bool Changed = false;
4589 TD = &getAnalysis<TargetData>();
4591 for (inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i)
4592 WorkList.push_back(&*i);
4595 while (!WorkList.empty()) {
4596 Instruction *I = WorkList.back(); // Get an instruction from the worklist
4597 WorkList.pop_back();
4599 // Check to see if we can DCE or ConstantPropagate the instruction...
4600 // Check to see if we can DIE the instruction...
4601 if (isInstructionTriviallyDead(I)) {
4602 // Add operands to the worklist...
4603 if (I->getNumOperands() < 4)
4604 AddUsesToWorkList(*I);
4607 I->getParent()->getInstList().erase(I);
4608 removeFromWorkList(I);
4612 // Instruction isn't dead, see if we can constant propagate it...
4613 if (Constant *C = ConstantFoldInstruction(I)) {
4614 Value* Ptr = I->getOperand(0);
4615 if (isa<GetElementPtrInst>(I) &&
4616 cast<Constant>(Ptr)->isNullValue() &&
4617 !isa<ConstantPointerNull>(C) &&
4618 cast<PointerType>(Ptr->getType())->getElementType()->isSized()) {
4619 // If this is a constant expr gep that is effectively computing an
4620 // "offsetof", fold it into 'cast int X to T*' instead of 'gep 0, 0, 12'
4621 bool isFoldableGEP = true;
4622 for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
4623 if (!isa<ConstantInt>(I->getOperand(i)))
4624 isFoldableGEP = false;
4625 if (isFoldableGEP) {
4626 uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
4627 std::vector<Value*>(I->op_begin()+1, I->op_end()));
4628 C = ConstantUInt::get(Type::ULongTy, Offset);
4629 C = ConstantExpr::getCast(C, TD->getIntPtrType());
4630 C = ConstantExpr::getCast(C, I->getType());
4634 // Add operands to the worklist...
4635 AddUsesToWorkList(*I);
4636 ReplaceInstUsesWith(*I, C);
4639 I->getParent()->getInstList().erase(I);
4640 removeFromWorkList(I);
4644 // See if we can trivially sink this instruction to a successor basic block.
4645 if (I->hasOneUse()) {
4646 BasicBlock *BB = I->getParent();
4647 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
4648 if (UserParent != BB) {
4649 bool UserIsSuccessor = false;
4650 // See if the user is one of our successors.
4651 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
4652 if (*SI == UserParent) {
4653 UserIsSuccessor = true;
4657 // If the user is one of our immediate successors, and if that successor
4658 // only has us as a predecessors (we'd have to split the critical edge
4659 // otherwise), we can keep going.
4660 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
4661 next(pred_begin(UserParent)) == pred_end(UserParent))
4662 // Okay, the CFG is simple enough, try to sink this instruction.
4663 Changed |= TryToSinkInstruction(I, UserParent);
4667 // Now that we have an instruction, try combining it to simplify it...
4668 if (Instruction *Result = visit(*I)) {
4670 // Should we replace the old instruction with a new one?
4672 DEBUG(std::cerr << "IC: Old = " << *I
4673 << " New = " << *Result);
4675 // Everything uses the new instruction now.
4676 I->replaceAllUsesWith(Result);
4678 // Push the new instruction and any users onto the worklist.
4679 WorkList.push_back(Result);
4680 AddUsersToWorkList(*Result);
4682 // Move the name to the new instruction first...
4683 std::string OldName = I->getName(); I->setName("");
4684 Result->setName(OldName);
4686 // Insert the new instruction into the basic block...
4687 BasicBlock *InstParent = I->getParent();
4688 BasicBlock::iterator InsertPos = I;
4690 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
4691 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
4694 InstParent->getInstList().insert(InsertPos, Result);
4696 // Make sure that we reprocess all operands now that we reduced their
4698 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
4699 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
4700 WorkList.push_back(OpI);
4702 // Instructions can end up on the worklist more than once. Make sure
4703 // we do not process an instruction that has been deleted.
4704 removeFromWorkList(I);
4706 // Erase the old instruction.
4707 InstParent->getInstList().erase(I);
4709 DEBUG(std::cerr << "IC: MOD = " << *I);
4711 // If the instruction was modified, it's possible that it is now dead.
4712 // if so, remove it.
4713 if (isInstructionTriviallyDead(I)) {
4714 // Make sure we process all operands now that we are reducing their
4716 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
4717 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
4718 WorkList.push_back(OpI);
4720 // Instructions may end up in the worklist more than once. Erase all
4721 // occurrances of this instruction.
4722 removeFromWorkList(I);
4723 I->getParent()->getInstList().erase(I);
4725 WorkList.push_back(Result);
4726 AddUsersToWorkList(*Result);
4736 FunctionPass *llvm::createInstructionCombiningPass() {
4737 return new InstCombiner();