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
32 // N. This list is incomplete
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/GetElementPtrTypeIterator.h"
47 #include "llvm/Support/InstIterator.h"
48 #include "llvm/Support/InstVisitor.h"
49 #include "llvm/Support/PatternMatch.h"
50 #include "llvm/Support/Debug.h"
51 #include "llvm/ADT/Statistic.h"
54 using namespace llvm::PatternMatch;
57 Statistic<> NumCombined ("instcombine", "Number of insts combined");
58 Statistic<> NumConstProp("instcombine", "Number of constant folds");
59 Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
61 class InstCombiner : public FunctionPass,
62 public InstVisitor<InstCombiner, Instruction*> {
63 // Worklist of all of the instructions that need to be simplified.
64 std::vector<Instruction*> WorkList;
67 /// AddUsersToWorkList - When an instruction is simplified, add all users of
68 /// the instruction to the work lists because they might get more simplified
71 void AddUsersToWorkList(Instruction &I) {
72 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
74 WorkList.push_back(cast<Instruction>(*UI));
77 /// AddUsesToWorkList - When an instruction is simplified, add operands to
78 /// the work lists because they might get more simplified now.
80 void AddUsesToWorkList(Instruction &I) {
81 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
82 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
83 WorkList.push_back(Op);
86 // removeFromWorkList - remove all instances of I from the worklist.
87 void removeFromWorkList(Instruction *I);
89 virtual bool runOnFunction(Function &F);
91 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
92 AU.addRequired<TargetData>();
96 TargetData &getTargetData() const { return *TD; }
98 // Visitation implementation - Implement instruction combining for different
99 // instruction types. The semantics are as follows:
101 // null - No change was made
102 // I - Change was made, I is still valid, I may be dead though
103 // otherwise - Change was made, replace I with returned instruction
105 Instruction *visitAdd(BinaryOperator &I);
106 Instruction *visitSub(BinaryOperator &I);
107 Instruction *visitMul(BinaryOperator &I);
108 Instruction *visitDiv(BinaryOperator &I);
109 Instruction *visitRem(BinaryOperator &I);
110 Instruction *visitAnd(BinaryOperator &I);
111 Instruction *visitOr (BinaryOperator &I);
112 Instruction *visitXor(BinaryOperator &I);
113 Instruction *visitSetCondInst(BinaryOperator &I);
114 Instruction *visitShiftInst(ShiftInst &I);
115 Instruction *visitCastInst(CastInst &CI);
116 Instruction *visitSelectInst(SelectInst &CI);
117 Instruction *visitCallInst(CallInst &CI);
118 Instruction *visitInvokeInst(InvokeInst &II);
119 Instruction *visitPHINode(PHINode &PN);
120 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
121 Instruction *visitAllocationInst(AllocationInst &AI);
122 Instruction *visitFreeInst(FreeInst &FI);
123 Instruction *visitLoadInst(LoadInst &LI);
124 Instruction *visitStoreInst(StoreInst &SI);
125 Instruction *visitBranchInst(BranchInst &BI);
126 Instruction *visitSwitchInst(SwitchInst &SI);
128 // visitInstruction - Specify what to return for unhandled instructions...
129 Instruction *visitInstruction(Instruction &I) { return 0; }
132 Instruction *visitCallSite(CallSite CS);
133 bool transformConstExprCastCall(CallSite CS);
136 // InsertNewInstBefore - insert an instruction New before instruction Old
137 // in the program. Add the new instruction to the worklist.
139 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
140 assert(New && New->getParent() == 0 &&
141 "New instruction already inserted into a basic block!");
142 BasicBlock *BB = Old.getParent();
143 BB->getInstList().insert(&Old, New); // Insert inst
144 WorkList.push_back(New); // Add to worklist
148 /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
149 /// This also adds the cast to the worklist. Finally, this returns the
151 Value *InsertCastBefore(Value *V, const Type *Ty, Instruction &Pos) {
152 if (V->getType() == Ty) return V;
154 Instruction *C = new CastInst(V, Ty, V->getName(), &Pos);
155 WorkList.push_back(C);
159 // ReplaceInstUsesWith - This method is to be used when an instruction is
160 // found to be dead, replacable with another preexisting expression. Here
161 // we add all uses of I to the worklist, replace all uses of I with the new
162 // value, then return I, so that the inst combiner will know that I was
165 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
166 AddUsersToWorkList(I); // Add all modified instrs to worklist
168 I.replaceAllUsesWith(V);
171 // If we are replacing the instruction with itself, this must be in a
172 // segment of unreachable code, so just clobber the instruction.
173 I.replaceAllUsesWith(Constant::getNullValue(I.getType()));
178 // EraseInstFromFunction - When dealing with an instruction that has side
179 // effects or produces a void value, we can't rely on DCE to delete the
180 // instruction. Instead, visit methods should return the value returned by
182 Instruction *EraseInstFromFunction(Instruction &I) {
183 assert(I.use_empty() && "Cannot erase instruction that is used!");
184 AddUsesToWorkList(I);
185 removeFromWorkList(&I);
186 I.getParent()->getInstList().erase(&I);
187 return 0; // Don't do anything with FI
192 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
193 /// InsertBefore instruction. This is specialized a bit to avoid inserting
194 /// casts that are known to not do anything...
196 Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
197 Instruction *InsertBefore);
199 // SimplifyCommutative - This performs a few simplifications for commutative
201 bool SimplifyCommutative(BinaryOperator &I);
204 // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
205 // PHI node as operand #0, see if we can fold the instruction into the PHI
206 // (which is only possible if all operands to the PHI are constants).
207 Instruction *FoldOpIntoPhi(Instruction &I);
209 Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
210 ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
212 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
213 bool Inside, Instruction &IB);
216 RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
219 // getComplexity: Assign a complexity or rank value to LLVM Values...
220 // 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
221 static unsigned getComplexity(Value *V) {
222 if (isa<Instruction>(V)) {
223 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
227 if (isa<Argument>(V)) return 3;
228 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
231 // isOnlyUse - Return true if this instruction will be deleted if we stop using
233 static bool isOnlyUse(Value *V) {
234 return V->hasOneUse() || isa<Constant>(V);
237 // getPromotedType - Return the specified type promoted as it would be to pass
238 // though a va_arg area...
239 static const Type *getPromotedType(const Type *Ty) {
240 switch (Ty->getTypeID()) {
241 case Type::SByteTyID:
242 case Type::ShortTyID: return Type::IntTy;
243 case Type::UByteTyID:
244 case Type::UShortTyID: return Type::UIntTy;
245 case Type::FloatTyID: return Type::DoubleTy;
250 // SimplifyCommutative - This performs a few simplifications for commutative
253 // 1. Order operands such that they are listed from right (least complex) to
254 // left (most complex). This puts constants before unary operators before
257 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
258 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
260 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
261 bool Changed = false;
262 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
263 Changed = !I.swapOperands();
265 if (!I.isAssociative()) return Changed;
266 Instruction::BinaryOps Opcode = I.getOpcode();
267 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
268 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
269 if (isa<Constant>(I.getOperand(1))) {
270 Constant *Folded = ConstantExpr::get(I.getOpcode(),
271 cast<Constant>(I.getOperand(1)),
272 cast<Constant>(Op->getOperand(1)));
273 I.setOperand(0, Op->getOperand(0));
274 I.setOperand(1, Folded);
276 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
277 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
278 isOnlyUse(Op) && isOnlyUse(Op1)) {
279 Constant *C1 = cast<Constant>(Op->getOperand(1));
280 Constant *C2 = cast<Constant>(Op1->getOperand(1));
282 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
283 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
284 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
287 WorkList.push_back(New);
288 I.setOperand(0, New);
289 I.setOperand(1, Folded);
296 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
297 // if the LHS is a constant zero (which is the 'negate' form).
299 static inline Value *dyn_castNegVal(Value *V) {
300 if (BinaryOperator::isNeg(V))
301 return BinaryOperator::getNegArgument(cast<BinaryOperator>(V));
303 // Constants can be considered to be negated values if they can be folded...
304 if (Constant *C = dyn_cast<Constant>(V))
305 return ConstantExpr::getNeg(C);
309 static inline Value *dyn_castNotVal(Value *V) {
310 if (BinaryOperator::isNot(V))
311 return BinaryOperator::getNotArgument(cast<BinaryOperator>(V));
313 // Constants can be considered to be not'ed values...
314 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
315 return ConstantExpr::getNot(C);
319 // dyn_castFoldableMul - If this value is a multiply that can be folded into
320 // other computations (because it has a constant operand), return the
321 // non-constant operand of the multiply.
323 static inline Value *dyn_castFoldableMul(Value *V) {
324 if (V->hasOneUse() && V->getType()->isInteger())
325 if (Instruction *I = dyn_cast<Instruction>(V))
326 if (I->getOpcode() == Instruction::Mul)
327 if (isa<Constant>(I->getOperand(1)))
328 return I->getOperand(0);
332 // Log2 - Calculate the log base 2 for the specified value if it is exactly a
334 static unsigned Log2(uint64_t Val) {
335 assert(Val > 1 && "Values 0 and 1 should be handled elsewhere!");
338 if (Val & 1) return 0; // Multiple bits set?
345 // AddOne, SubOne - Add or subtract a constant one from an integer constant...
346 static ConstantInt *AddOne(ConstantInt *C) {
347 return cast<ConstantInt>(ConstantExpr::getAdd(C,
348 ConstantInt::get(C->getType(), 1)));
350 static ConstantInt *SubOne(ConstantInt *C) {
351 return cast<ConstantInt>(ConstantExpr::getSub(C,
352 ConstantInt::get(C->getType(), 1)));
355 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
356 // true when both operands are equal...
358 static bool isTrueWhenEqual(Instruction &I) {
359 return I.getOpcode() == Instruction::SetEQ ||
360 I.getOpcode() == Instruction::SetGE ||
361 I.getOpcode() == Instruction::SetLE;
364 /// AssociativeOpt - Perform an optimization on an associative operator. This
365 /// function is designed to check a chain of associative operators for a
366 /// potential to apply a certain optimization. Since the optimization may be
367 /// applicable if the expression was reassociated, this checks the chain, then
368 /// reassociates the expression as necessary to expose the optimization
369 /// opportunity. This makes use of a special Functor, which must define
370 /// 'shouldApply' and 'apply' methods.
372 template<typename Functor>
373 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
374 unsigned Opcode = Root.getOpcode();
375 Value *LHS = Root.getOperand(0);
377 // Quick check, see if the immediate LHS matches...
378 if (F.shouldApply(LHS))
379 return F.apply(Root);
381 // Otherwise, if the LHS is not of the same opcode as the root, return.
382 Instruction *LHSI = dyn_cast<Instruction>(LHS);
383 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
384 // Should we apply this transform to the RHS?
385 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
387 // If not to the RHS, check to see if we should apply to the LHS...
388 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
389 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
393 // If the functor wants to apply the optimization to the RHS of LHSI,
394 // reassociate the expression from ((? op A) op B) to (? op (A op B))
396 BasicBlock *BB = Root.getParent();
398 // Now all of the instructions are in the current basic block, go ahead
399 // and perform the reassociation.
400 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
402 // First move the selected RHS to the LHS of the root...
403 Root.setOperand(0, LHSI->getOperand(1));
405 // Make what used to be the LHS of the root be the user of the root...
406 Value *ExtraOperand = TmpLHSI->getOperand(1);
407 if (&Root == TmpLHSI) {
408 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
411 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
412 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
413 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
414 BasicBlock::iterator ARI = &Root; ++ARI;
415 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
418 // Now propagate the ExtraOperand down the chain of instructions until we
420 while (TmpLHSI != LHSI) {
421 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
422 // Move the instruction to immediately before the chain we are
423 // constructing to avoid breaking dominance properties.
424 NextLHSI->getParent()->getInstList().remove(NextLHSI);
425 BB->getInstList().insert(ARI, NextLHSI);
428 Value *NextOp = NextLHSI->getOperand(1);
429 NextLHSI->setOperand(1, ExtraOperand);
431 ExtraOperand = NextOp;
434 // Now that the instructions are reassociated, have the functor perform
435 // the transformation...
436 return F.apply(Root);
439 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
445 // AddRHS - Implements: X + X --> X << 1
448 AddRHS(Value *rhs) : RHS(rhs) {}
449 bool shouldApply(Value *LHS) const { return LHS == RHS; }
450 Instruction *apply(BinaryOperator &Add) const {
451 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
452 ConstantInt::get(Type::UByteTy, 1));
456 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
458 struct AddMaskingAnd {
460 AddMaskingAnd(Constant *c) : C2(c) {}
461 bool shouldApply(Value *LHS) const {
463 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
464 ConstantExpr::getAnd(C1, C2)->isNullValue();
466 Instruction *apply(BinaryOperator &Add) const {
467 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
471 static Value *FoldOperationIntoSelectOperand(Instruction &BI, Value *SO,
473 // Figure out if the constant is the left or the right argument.
474 bool ConstIsRHS = isa<Constant>(BI.getOperand(1));
475 Constant *ConstOperand = cast<Constant>(BI.getOperand(ConstIsRHS));
477 if (Constant *SOC = dyn_cast<Constant>(SO)) {
479 return ConstantExpr::get(BI.getOpcode(), SOC, ConstOperand);
480 return ConstantExpr::get(BI.getOpcode(), ConstOperand, SOC);
483 Value *Op0 = SO, *Op1 = ConstOperand;
487 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&BI))
488 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1);
489 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&BI))
490 New = new ShiftInst(SI->getOpcode(), Op0, Op1);
492 assert(0 && "Unknown binary instruction type!");
495 return IC->InsertNewInstBefore(New, BI);
499 /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
500 /// node as operand #0, see if we can fold the instruction into the PHI (which
501 /// is only possible if all operands to the PHI are constants).
502 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
503 PHINode *PN = cast<PHINode>(I.getOperand(0));
504 if (!PN->hasOneUse()) return 0;
506 // Check to see if all of the operands of the PHI are constants. If not, we
507 // cannot do the transformation.
508 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
509 if (!isa<Constant>(PN->getIncomingValue(i)))
512 // Okay, we can do the transformation: create the new PHI node.
513 PHINode *NewPN = new PHINode(I.getType(), I.getName());
515 NewPN->op_reserve(PN->getNumOperands());
516 InsertNewInstBefore(NewPN, *PN);
518 // Next, add all of the operands to the PHI.
519 if (I.getNumOperands() == 2) {
520 Constant *C = cast<Constant>(I.getOperand(1));
521 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
522 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
523 NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
524 PN->getIncomingBlock(i));
527 assert(isa<CastInst>(I) && "Unary op should be a cast!");
528 const Type *RetTy = I.getType();
529 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
530 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
531 NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
532 PN->getIncomingBlock(i));
535 return ReplaceInstUsesWith(I, NewPN);
538 // FoldBinOpIntoSelect - Given an instruction with a select as one operand and a
539 // constant as the other operand, try to fold the binary operator into the
541 static Instruction *FoldBinOpIntoSelect(Instruction &BI, SelectInst *SI,
543 // Don't modify shared select instructions
544 if (!SI->hasOneUse()) return 0;
545 Value *TV = SI->getOperand(1);
546 Value *FV = SI->getOperand(2);
548 if (isa<Constant>(TV) || isa<Constant>(FV)) {
549 Value *SelectTrueVal = FoldOperationIntoSelectOperand(BI, TV, IC);
550 Value *SelectFalseVal = FoldOperationIntoSelectOperand(BI, FV, IC);
552 return new SelectInst(SI->getCondition(), SelectTrueVal,
558 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
559 bool Changed = SimplifyCommutative(I);
560 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
562 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
563 // X + undef -> undef
564 if (isa<UndefValue>(RHS))
565 return ReplaceInstUsesWith(I, RHS);
568 if (!I.getType()->isFloatingPoint() && // -0 + +0 = +0, so it's not a noop
570 return ReplaceInstUsesWith(I, LHS);
572 // X + (signbit) --> X ^ signbit
573 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
574 unsigned NumBits = CI->getType()->getPrimitiveSize()*8;
575 uint64_t Val = CI->getRawValue() & (1ULL << NumBits)-1;
576 if (Val == (1ULL << NumBits-1))
577 return BinaryOperator::createXor(LHS, RHS);
580 if (isa<PHINode>(LHS))
581 if (Instruction *NV = FoldOpIntoPhi(I))
586 if (I.getType()->isInteger()) {
587 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
591 if (Value *V = dyn_castNegVal(LHS))
592 return BinaryOperator::createSub(RHS, V);
595 if (!isa<Constant>(RHS))
596 if (Value *V = dyn_castNegVal(RHS))
597 return BinaryOperator::createSub(LHS, V);
599 // X*C + X --> X * (C+1)
600 if (dyn_castFoldableMul(LHS) == RHS) {
602 ConstantExpr::getAdd(
603 cast<Constant>(cast<Instruction>(LHS)->getOperand(1)),
604 ConstantInt::get(I.getType(), 1));
605 return BinaryOperator::createMul(RHS, CP1);
608 // X + X*C --> X * (C+1)
609 if (dyn_castFoldableMul(RHS) == LHS) {
611 ConstantExpr::getAdd(
612 cast<Constant>(cast<Instruction>(RHS)->getOperand(1)),
613 ConstantInt::get(I.getType(), 1));
614 return BinaryOperator::createMul(LHS, CP1);
617 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
619 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
620 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
622 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
624 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
625 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
626 return BinaryOperator::createSub(C, X);
629 // (X & FF00) + xx00 -> (X+xx00) & FF00
630 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
631 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
633 // See if all bits from the first bit set in the Add RHS up are included
634 // in the mask. First, get the rightmost bit.
635 uint64_t AddRHSV = CRHS->getRawValue();
637 // Form a mask of all bits from the lowest bit added through the top.
638 uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
639 AddRHSHighBits &= (1ULL << C2->getType()->getPrimitiveSize()*8)-1;
641 // See if the and mask includes all of these bits.
642 uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue();
644 if (AddRHSHighBits == AddRHSHighBitsAnd) {
645 // Okay, the xform is safe. Insert the new add pronto.
646 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
648 return BinaryOperator::createAnd(NewAdd, C2);
654 // Try to fold constant add into select arguments.
655 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
656 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
660 return Changed ? &I : 0;
663 // isSignBit - Return true if the value represented by the constant only has the
664 // highest order bit set.
665 static bool isSignBit(ConstantInt *CI) {
666 unsigned NumBits = CI->getType()->getPrimitiveSize()*8;
667 return (CI->getRawValue() & ~(-1LL << NumBits)) == (1ULL << (NumBits-1));
670 static unsigned getTypeSizeInBits(const Type *Ty) {
671 return Ty == Type::BoolTy ? 1 : Ty->getPrimitiveSize()*8;
674 /// RemoveNoopCast - Strip off nonconverting casts from the value.
676 static Value *RemoveNoopCast(Value *V) {
677 if (CastInst *CI = dyn_cast<CastInst>(V)) {
678 const Type *CTy = CI->getType();
679 const Type *OpTy = CI->getOperand(0)->getType();
680 if (CTy->isInteger() && OpTy->isInteger()) {
681 if (CTy->getPrimitiveSize() == OpTy->getPrimitiveSize())
682 return RemoveNoopCast(CI->getOperand(0));
683 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
684 return RemoveNoopCast(CI->getOperand(0));
689 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
690 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
692 if (Op0 == Op1) // sub X, X -> 0
693 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
695 // If this is a 'B = x-(-A)', change to B = x+A...
696 if (Value *V = dyn_castNegVal(Op1))
697 return BinaryOperator::createAdd(Op0, V);
699 if (isa<UndefValue>(Op0))
700 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
701 if (isa<UndefValue>(Op1))
702 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
704 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
705 // Replace (-1 - A) with (~A)...
706 if (C->isAllOnesValue())
707 return BinaryOperator::createNot(Op1);
709 // C - ~X == X + (1+C)
711 if (match(Op1, m_Not(m_Value(X))))
712 return BinaryOperator::createAdd(X,
713 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
714 // -((uint)X >> 31) -> ((int)X >> 31)
715 // -((int)X >> 31) -> ((uint)X >> 31)
716 if (C->isNullValue()) {
717 Value *NoopCastedRHS = RemoveNoopCast(Op1);
718 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
719 if (SI->getOpcode() == Instruction::Shr)
720 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
722 if (SI->getType()->isSigned())
723 NewTy = SI->getType()->getUnsignedVersion();
725 NewTy = SI->getType()->getSignedVersion();
726 // Check to see if we are shifting out everything but the sign bit.
727 if (CU->getValue() == SI->getType()->getPrimitiveSize()*8-1) {
728 // Ok, the transformation is safe. Insert a cast of the incoming
729 // value, then the new shift, then the new cast.
730 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
731 SI->getOperand(0)->getName());
732 Value *InV = InsertNewInstBefore(FirstCast, I);
733 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
735 if (NewShift->getType() == I.getType())
738 InV = InsertNewInstBefore(NewShift, I);
739 return new CastInst(NewShift, I.getType());
745 // Try to fold constant sub into select arguments.
746 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
747 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
750 if (isa<PHINode>(Op0))
751 if (Instruction *NV = FoldOpIntoPhi(I))
755 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1))
756 if (Op1I->hasOneUse()) {
757 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
758 // is not used by anyone else...
760 if (Op1I->getOpcode() == Instruction::Sub &&
761 !Op1I->getType()->isFloatingPoint()) {
762 // Swap the two operands of the subexpr...
763 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
764 Op1I->setOperand(0, IIOp1);
765 Op1I->setOperand(1, IIOp0);
767 // Create the new top level add instruction...
768 return BinaryOperator::createAdd(Op0, Op1);
771 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
773 if (Op1I->getOpcode() == Instruction::And &&
774 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
775 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
778 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
779 return BinaryOperator::createAnd(Op0, NewNot);
782 // -(X sdiv C) -> (X sdiv -C)
783 if (Op1I->getOpcode() == Instruction::Div)
784 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
785 if (CSI->getValue() == 0)
786 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
787 return BinaryOperator::createDiv(Op1I->getOperand(0),
788 ConstantExpr::getNeg(DivRHS));
790 // X - X*C --> X * (1-C)
791 if (dyn_castFoldableMul(Op1I) == Op0) {
793 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1),
794 cast<Constant>(cast<Instruction>(Op1)->getOperand(1)));
795 assert(CP1 && "Couldn't constant fold 1-C?");
796 return BinaryOperator::createMul(Op0, CP1);
800 // X*C - X --> X * (C-1)
801 if (dyn_castFoldableMul(Op0) == Op1) {
803 ConstantExpr::getSub(cast<Constant>(cast<Instruction>(Op0)->getOperand(1)),
804 ConstantInt::get(I.getType(), 1));
805 assert(CP1 && "Couldn't constant fold C - 1?");
806 return BinaryOperator::createMul(Op1, CP1);
812 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
813 /// really just returns true if the most significant (sign) bit is set.
814 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
815 if (RHS->getType()->isSigned()) {
816 // True if source is LHS < 0 or LHS <= -1
817 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
818 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
820 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
821 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
822 // the size of the integer type.
823 if (Opcode == Instruction::SetGE)
824 return RHSC->getValue() == 1ULL<<(RHS->getType()->getPrimitiveSize()*8-1);
825 if (Opcode == Instruction::SetGT)
826 return RHSC->getValue() ==
827 (1ULL << (RHS->getType()->getPrimitiveSize()*8-1))-1;
832 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
833 bool Changed = SimplifyCommutative(I);
834 Value *Op0 = I.getOperand(0);
836 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
837 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
839 // Simplify mul instructions with a constant RHS...
840 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
841 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
843 // ((X << C1)*C2) == (X * (C2 << C1))
844 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
845 if (SI->getOpcode() == Instruction::Shl)
846 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
847 return BinaryOperator::createMul(SI->getOperand(0),
848 ConstantExpr::getShl(CI, ShOp));
850 if (CI->isNullValue())
851 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
852 if (CI->equalsInt(1)) // X * 1 == X
853 return ReplaceInstUsesWith(I, Op0);
854 if (CI->isAllOnesValue()) // X * -1 == 0 - X
855 return BinaryOperator::createNeg(Op0, I.getName());
857 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
858 if (uint64_t C = Log2(Val)) // Replace X*(2^C) with X << C
859 return new ShiftInst(Instruction::Shl, Op0,
860 ConstantUInt::get(Type::UByteTy, C));
861 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
862 if (Op1F->isNullValue())
863 return ReplaceInstUsesWith(I, Op1);
865 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
866 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
867 if (Op1F->getValue() == 1.0)
868 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
871 // Try to fold constant mul into select arguments.
872 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
873 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
876 if (isa<PHINode>(Op0))
877 if (Instruction *NV = FoldOpIntoPhi(I))
881 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
882 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
883 return BinaryOperator::createMul(Op0v, Op1v);
885 // If one of the operands of the multiply is a cast from a boolean value, then
886 // we know the bool is either zero or one, so this is a 'masking' multiply.
887 // See if we can simplify things based on how the boolean was originally
889 CastInst *BoolCast = 0;
890 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
891 if (CI->getOperand(0)->getType() == Type::BoolTy)
894 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
895 if (CI->getOperand(0)->getType() == Type::BoolTy)
898 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
899 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
900 const Type *SCOpTy = SCIOp0->getType();
902 // If the setcc is true iff the sign bit of X is set, then convert this
903 // multiply into a shift/and combination.
904 if (isa<ConstantInt>(SCIOp1) &&
905 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
906 // Shift the X value right to turn it into "all signbits".
907 Constant *Amt = ConstantUInt::get(Type::UByteTy,
908 SCOpTy->getPrimitiveSize()*8-1);
909 if (SCIOp0->getType()->isUnsigned()) {
910 const Type *NewTy = SCIOp0->getType()->getSignedVersion();
911 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
912 SCIOp0->getName()), I);
916 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
917 BoolCast->getOperand(0)->getName()+
920 // If the multiply type is not the same as the source type, sign extend
921 // or truncate to the multiply type.
922 if (I.getType() != V->getType())
923 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
925 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
926 return BinaryOperator::createAnd(V, OtherOp);
931 return Changed ? &I : 0;
934 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
935 if (isa<UndefValue>(I.getOperand(0))) // undef / X -> 0
936 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
937 if (isa<UndefValue>(I.getOperand(1)))
938 return ReplaceInstUsesWith(I, I.getOperand(1)); // X / undef -> undef
940 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
942 if (RHS->equalsInt(1))
943 return ReplaceInstUsesWith(I, I.getOperand(0));
946 if (RHS->isAllOnesValue())
947 return BinaryOperator::createNeg(I.getOperand(0));
949 if (Instruction *LHS = dyn_cast<Instruction>(I.getOperand(0)))
950 if (LHS->getOpcode() == Instruction::Div)
951 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
952 // (X / C1) / C2 -> X / (C1*C2)
953 return BinaryOperator::createDiv(LHS->getOperand(0),
954 ConstantExpr::getMul(RHS, LHSRHS));
957 // Check to see if this is an unsigned division with an exact power of 2,
958 // if so, convert to a right shift.
959 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
960 if (uint64_t Val = C->getValue()) // Don't break X / 0
961 if (uint64_t C = Log2(Val))
962 return new ShiftInst(Instruction::Shr, I.getOperand(0),
963 ConstantUInt::get(Type::UByteTy, C));
966 if (RHS->getType()->isSigned())
967 if (Value *LHSNeg = dyn_castNegVal(I.getOperand(0)))
968 return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS));
970 if (isa<PHINode>(I.getOperand(0)) && !RHS->isNullValue())
971 if (Instruction *NV = FoldOpIntoPhi(I))
975 // 0 / X == 0, we don't need to preserve faults!
976 if (ConstantInt *LHS = dyn_cast<ConstantInt>(I.getOperand(0)))
977 if (LHS->equalsInt(0))
978 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
984 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
985 if (I.getType()->isSigned())
986 if (Value *RHSNeg = dyn_castNegVal(I.getOperand(1)))
987 if (!isa<ConstantSInt>(RHSNeg) ||
988 cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
990 AddUsesToWorkList(I);
991 I.setOperand(1, RHSNeg);
995 if (isa<UndefValue>(I.getOperand(0))) // undef % X -> 0
996 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
997 if (isa<UndefValue>(I.getOperand(1)))
998 return ReplaceInstUsesWith(I, I.getOperand(1)); // X % undef -> undef
1000 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
1001 if (RHS->equalsInt(1)) // X % 1 == 0
1002 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1004 // Check to see if this is an unsigned remainder with an exact power of 2,
1005 // if so, convert to a bitwise and.
1006 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1007 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
1008 if (!(Val & (Val-1))) // Power of 2
1009 return BinaryOperator::createAnd(I.getOperand(0),
1010 ConstantUInt::get(I.getType(), Val-1));
1011 if (isa<PHINode>(I.getOperand(0)) && !RHS->isNullValue())
1012 if (Instruction *NV = FoldOpIntoPhi(I))
1016 // 0 % X == 0, we don't need to preserve faults!
1017 if (ConstantInt *LHS = dyn_cast<ConstantInt>(I.getOperand(0)))
1018 if (LHS->equalsInt(0))
1019 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1024 // isMaxValueMinusOne - return true if this is Max-1
1025 static bool isMaxValueMinusOne(const ConstantInt *C) {
1026 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
1027 // Calculate -1 casted to the right type...
1028 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
1029 uint64_t Val = ~0ULL; // All ones
1030 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1031 return CU->getValue() == Val-1;
1034 const ConstantSInt *CS = cast<ConstantSInt>(C);
1036 // Calculate 0111111111..11111
1037 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
1038 int64_t Val = INT64_MAX; // All ones
1039 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1040 return CS->getValue() == Val-1;
1043 // isMinValuePlusOne - return true if this is Min+1
1044 static bool isMinValuePlusOne(const ConstantInt *C) {
1045 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1046 return CU->getValue() == 1;
1048 const ConstantSInt *CS = cast<ConstantSInt>(C);
1050 // Calculate 1111111111000000000000
1051 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
1052 int64_t Val = -1; // All ones
1053 Val <<= TypeBits-1; // Shift over to the right spot
1054 return CS->getValue() == Val+1;
1057 // isOneBitSet - Return true if there is exactly one bit set in the specified
1059 static bool isOneBitSet(const ConstantInt *CI) {
1060 uint64_t V = CI->getRawValue();
1061 return V && (V & (V-1)) == 0;
1064 #if 0 // Currently unused
1065 // isLowOnes - Return true if the constant is of the form 0+1+.
1066 static bool isLowOnes(const ConstantInt *CI) {
1067 uint64_t V = CI->getRawValue();
1069 // There won't be bits set in parts that the type doesn't contain.
1070 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1072 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1073 return U && V && (U & V) == 0;
1077 // isHighOnes - Return true if the constant is of the form 1+0+.
1078 // This is the same as lowones(~X).
1079 static bool isHighOnes(const ConstantInt *CI) {
1080 uint64_t V = ~CI->getRawValue();
1082 // There won't be bits set in parts that the type doesn't contain.
1083 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1085 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1086 return U && V && (U & V) == 0;
1090 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
1091 /// are carefully arranged to allow folding of expressions such as:
1093 /// (A < B) | (A > B) --> (A != B)
1095 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
1096 /// represents that the comparison is true if A == B, and bit value '1' is true
1099 static unsigned getSetCondCode(const SetCondInst *SCI) {
1100 switch (SCI->getOpcode()) {
1102 case Instruction::SetGT: return 1;
1103 case Instruction::SetEQ: return 2;
1104 case Instruction::SetGE: return 3;
1105 case Instruction::SetLT: return 4;
1106 case Instruction::SetNE: return 5;
1107 case Instruction::SetLE: return 6;
1110 assert(0 && "Invalid SetCC opcode!");
1115 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
1116 /// opcode and two operands into either a constant true or false, or a brand new
1117 /// SetCC instruction.
1118 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
1120 case 0: return ConstantBool::False;
1121 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
1122 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
1123 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
1124 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
1125 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
1126 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
1127 case 7: return ConstantBool::True;
1128 default: assert(0 && "Illegal SetCCCode!"); return 0;
1132 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1133 struct FoldSetCCLogical {
1136 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
1137 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
1138 bool shouldApply(Value *V) const {
1139 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
1140 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
1141 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
1144 Instruction *apply(BinaryOperator &Log) const {
1145 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
1146 if (SCI->getOperand(0) != LHS) {
1147 assert(SCI->getOperand(1) == LHS);
1148 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
1151 unsigned LHSCode = getSetCondCode(SCI);
1152 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
1154 switch (Log.getOpcode()) {
1155 case Instruction::And: Code = LHSCode & RHSCode; break;
1156 case Instruction::Or: Code = LHSCode | RHSCode; break;
1157 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
1158 default: assert(0 && "Illegal logical opcode!"); return 0;
1161 Value *RV = getSetCCValue(Code, LHS, RHS);
1162 if (Instruction *I = dyn_cast<Instruction>(RV))
1164 // Otherwise, it's a constant boolean value...
1165 return IC.ReplaceInstUsesWith(Log, RV);
1170 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
1171 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
1172 // guaranteed to be either a shift instruction or a binary operator.
1173 Instruction *InstCombiner::OptAndOp(Instruction *Op,
1174 ConstantIntegral *OpRHS,
1175 ConstantIntegral *AndRHS,
1176 BinaryOperator &TheAnd) {
1177 Value *X = Op->getOperand(0);
1178 Constant *Together = 0;
1179 if (!isa<ShiftInst>(Op))
1180 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
1182 switch (Op->getOpcode()) {
1183 case Instruction::Xor:
1184 if (Together->isNullValue()) {
1185 // (X ^ C1) & C2 --> (X & C2) iff (C1&C2) == 0
1186 return BinaryOperator::createAnd(X, AndRHS);
1187 } else if (Op->hasOneUse()) {
1188 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
1189 std::string OpName = Op->getName(); Op->setName("");
1190 Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
1191 InsertNewInstBefore(And, TheAnd);
1192 return BinaryOperator::createXor(And, Together);
1195 case Instruction::Or:
1196 // (X | C1) & C2 --> X & C2 iff C1 & C1 == 0
1197 if (Together->isNullValue())
1198 return BinaryOperator::createAnd(X, AndRHS);
1200 if (Together == AndRHS) // (X | C) & C --> C
1201 return ReplaceInstUsesWith(TheAnd, AndRHS);
1203 if (Op->hasOneUse() && Together != OpRHS) {
1204 // (X | C1) & C2 --> (X | (C1&C2)) & C2
1205 std::string Op0Name = Op->getName(); Op->setName("");
1206 Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
1207 InsertNewInstBefore(Or, TheAnd);
1208 return BinaryOperator::createAnd(Or, AndRHS);
1212 case Instruction::Add:
1213 if (Op->hasOneUse()) {
1214 // Adding a one to a single bit bit-field should be turned into an XOR
1215 // of the bit. First thing to check is to see if this AND is with a
1216 // single bit constant.
1217 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
1219 // Clear bits that are not part of the constant.
1220 AndRHSV &= (1ULL << AndRHS->getType()->getPrimitiveSize()*8)-1;
1222 // If there is only one bit set...
1223 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
1224 // Ok, at this point, we know that we are masking the result of the
1225 // ADD down to exactly one bit. If the constant we are adding has
1226 // no bits set below this bit, then we can eliminate the ADD.
1227 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
1229 // Check to see if any bits below the one bit set in AndRHSV are set.
1230 if ((AddRHS & (AndRHSV-1)) == 0) {
1231 // If not, the only thing that can effect the output of the AND is
1232 // the bit specified by AndRHSV. If that bit is set, the effect of
1233 // the XOR is to toggle the bit. If it is clear, then the ADD has
1235 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
1236 TheAnd.setOperand(0, X);
1239 std::string Name = Op->getName(); Op->setName("");
1240 // Pull the XOR out of the AND.
1241 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
1242 InsertNewInstBefore(NewAnd, TheAnd);
1243 return BinaryOperator::createXor(NewAnd, AndRHS);
1250 case Instruction::Shl: {
1251 // We know that the AND will not produce any of the bits shifted in, so if
1252 // the anded constant includes them, clear them now!
1254 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1255 Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
1256 Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
1258 if (CI == ShlMask) { // Masking out bits that the shift already masks
1259 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
1260 } else if (CI != AndRHS) { // Reducing bits set in and.
1261 TheAnd.setOperand(1, CI);
1266 case Instruction::Shr:
1267 // We know that the AND will not produce any of the bits shifted in, so if
1268 // the anded constant includes them, clear them now! This only applies to
1269 // unsigned shifts, because a signed shr may bring in set bits!
1271 if (AndRHS->getType()->isUnsigned()) {
1272 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1273 Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS);
1274 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1276 if (CI == ShrMask) { // Masking out bits that the shift already masks.
1277 return ReplaceInstUsesWith(TheAnd, Op);
1278 } else if (CI != AndRHS) {
1279 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
1282 } else { // Signed shr.
1283 // See if this is shifting in some sign extension, then masking it out
1285 if (Op->hasOneUse()) {
1286 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1287 Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS);
1288 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1289 if (CI == ShrMask) { // Masking out bits shifted in.
1290 // Make the argument unsigned.
1291 Value *ShVal = Op->getOperand(0);
1292 ShVal = InsertCastBefore(ShVal,
1293 ShVal->getType()->getUnsignedVersion(),
1295 ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal,
1296 OpRHS, Op->getName()),
1298 return new CastInst(ShVal, Op->getType());
1308 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
1309 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
1310 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. IB is the location to
1311 /// insert new instructions.
1312 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
1313 bool Inside, Instruction &IB) {
1314 assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
1315 "Lo is not <= Hi in range emission code!");
1317 if (Lo == Hi) // Trivially false.
1318 return new SetCondInst(Instruction::SetNE, V, V);
1319 if (cast<ConstantIntegral>(Lo)->isMinValue())
1320 return new SetCondInst(Instruction::SetLT, V, Hi);
1322 Constant *AddCST = ConstantExpr::getNeg(Lo);
1323 Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
1324 InsertNewInstBefore(Add, IB);
1325 // Convert to unsigned for the comparison.
1326 const Type *UnsType = Add->getType()->getUnsignedVersion();
1327 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1328 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1329 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1330 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1333 if (Lo == Hi) // Trivially true.
1334 return new SetCondInst(Instruction::SetEQ, V, V);
1336 Hi = SubOne(cast<ConstantInt>(Hi));
1337 if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
1338 return new SetCondInst(Instruction::SetGT, V, Hi);
1340 // Emit X-Lo > Hi-Lo-1
1341 Constant *AddCST = ConstantExpr::getNeg(Lo);
1342 Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
1343 InsertNewInstBefore(Add, IB);
1344 // Convert to unsigned for the comparison.
1345 const Type *UnsType = Add->getType()->getUnsignedVersion();
1346 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1347 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1348 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1349 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1353 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1354 bool Changed = SimplifyCommutative(I);
1355 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1357 if (isa<UndefValue>(Op1)) // X & undef -> 0
1358 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1360 // and X, X = X and X, 0 == 0
1361 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
1362 return ReplaceInstUsesWith(I, Op1);
1365 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1366 if (RHS->isAllOnesValue())
1367 return ReplaceInstUsesWith(I, Op0);
1369 // Optimize a variety of ((val OP C1) & C2) combinations...
1370 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
1371 Instruction *Op0I = cast<Instruction>(Op0);
1372 Value *X = Op0I->getOperand(0);
1373 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1374 if (Instruction *Res = OptAndOp(Op0I, Op0CI, RHS, I))
1378 // Try to fold constant and into select arguments.
1379 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1380 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1382 if (isa<PHINode>(Op0))
1383 if (Instruction *NV = FoldOpIntoPhi(I))
1387 Value *Op0NotVal = dyn_castNotVal(Op0);
1388 Value *Op1NotVal = dyn_castNotVal(Op1);
1390 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1391 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1393 // (~A & ~B) == (~(A | B)) - De Morgan's Law
1394 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1395 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
1396 I.getName()+".demorgan");
1397 InsertNewInstBefore(Or, I);
1398 return BinaryOperator::createNot(Or);
1401 if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
1402 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1403 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1406 Value *LHSVal, *RHSVal;
1407 ConstantInt *LHSCst, *RHSCst;
1408 Instruction::BinaryOps LHSCC, RHSCC;
1409 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1410 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1411 if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
1412 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1413 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1414 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1415 // Ensure that the larger constant is on the RHS.
1416 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1417 SetCondInst *LHS = cast<SetCondInst>(Op0);
1418 if (cast<ConstantBool>(Cmp)->getValue()) {
1419 std::swap(LHS, RHS);
1420 std::swap(LHSCst, RHSCst);
1421 std::swap(LHSCC, RHSCC);
1424 // At this point, we know we have have two setcc instructions
1425 // comparing a value against two constants and and'ing the result
1426 // together. Because of the above check, we know that we only have
1427 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1428 // FoldSetCCLogical check above), that the two constants are not
1430 assert(LHSCst != RHSCst && "Compares not folded above?");
1433 default: assert(0 && "Unknown integer condition code!");
1434 case Instruction::SetEQ:
1436 default: assert(0 && "Unknown integer condition code!");
1437 case Instruction::SetEQ: // (X == 13 & X == 15) -> false
1438 case Instruction::SetGT: // (X == 13 & X > 15) -> false
1439 return ReplaceInstUsesWith(I, ConstantBool::False);
1440 case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
1441 case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
1442 return ReplaceInstUsesWith(I, LHS);
1444 case Instruction::SetNE:
1446 default: assert(0 && "Unknown integer condition code!");
1447 case Instruction::SetLT:
1448 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
1449 return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
1450 break; // (X != 13 & X < 15) -> no change
1451 case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
1452 case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
1453 return ReplaceInstUsesWith(I, RHS);
1454 case Instruction::SetNE:
1455 if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
1456 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1457 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
1458 LHSVal->getName()+".off");
1459 InsertNewInstBefore(Add, I);
1460 const Type *UnsType = Add->getType()->getUnsignedVersion();
1461 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
1462 AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
1463 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1464 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1466 break; // (X != 13 & X != 15) -> no change
1469 case Instruction::SetLT:
1471 default: assert(0 && "Unknown integer condition code!");
1472 case Instruction::SetEQ: // (X < 13 & X == 15) -> false
1473 case Instruction::SetGT: // (X < 13 & X > 15) -> false
1474 return ReplaceInstUsesWith(I, ConstantBool::False);
1475 case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
1476 case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
1477 return ReplaceInstUsesWith(I, LHS);
1479 case Instruction::SetGT:
1481 default: assert(0 && "Unknown integer condition code!");
1482 case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
1483 return ReplaceInstUsesWith(I, LHS);
1484 case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
1485 return ReplaceInstUsesWith(I, RHS);
1486 case Instruction::SetNE:
1487 if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
1488 return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
1489 break; // (X > 13 & X != 15) -> no change
1490 case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
1491 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
1497 return Changed ? &I : 0;
1500 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
1501 bool Changed = SimplifyCommutative(I);
1502 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1504 if (isa<UndefValue>(Op1))
1505 return ReplaceInstUsesWith(I, // X | undef -> -1
1506 ConstantIntegral::getAllOnesValue(I.getType()));
1508 // or X, X = X or X, 0 == X
1509 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
1510 return ReplaceInstUsesWith(I, Op0);
1513 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1514 if (RHS->isAllOnesValue())
1515 return ReplaceInstUsesWith(I, Op1);
1517 ConstantInt *C1; Value *X;
1518 // (X & C1) | C2 --> (X | C2) & (C1|C2)
1519 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1520 std::string Op0Name = Op0->getName(); Op0->setName("");
1521 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
1522 InsertNewInstBefore(Or, I);
1523 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
1526 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
1527 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1528 std::string Op0Name = Op0->getName(); Op0->setName("");
1529 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
1530 InsertNewInstBefore(Or, I);
1531 return BinaryOperator::createXor(Or,
1532 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
1535 // Try to fold constant and into select arguments.
1536 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1537 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1539 if (isa<PHINode>(Op0))
1540 if (Instruction *NV = FoldOpIntoPhi(I))
1544 // (A & C1)|(A & C2) == A & (C1|C2)
1545 Value *A, *B; ConstantInt *C1, *C2;
1546 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
1547 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) && A == B)
1548 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
1550 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
1551 if (A == Op1) // ~A | A == -1
1552 return ReplaceInstUsesWith(I,
1553 ConstantIntegral::getAllOnesValue(I.getType()));
1558 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
1560 return ReplaceInstUsesWith(I,
1561 ConstantIntegral::getAllOnesValue(I.getType()));
1563 // (~A | ~B) == (~(A & B)) - De Morgan's Law
1564 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1565 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
1566 I.getName()+".demorgan"), I);
1567 return BinaryOperator::createNot(And);
1571 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
1572 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
1573 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1576 Value *LHSVal, *RHSVal;
1577 ConstantInt *LHSCst, *RHSCst;
1578 Instruction::BinaryOps LHSCC, RHSCC;
1579 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1580 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1581 if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
1582 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1583 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1584 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1585 // Ensure that the larger constant is on the RHS.
1586 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1587 SetCondInst *LHS = cast<SetCondInst>(Op0);
1588 if (cast<ConstantBool>(Cmp)->getValue()) {
1589 std::swap(LHS, RHS);
1590 std::swap(LHSCst, RHSCst);
1591 std::swap(LHSCC, RHSCC);
1594 // At this point, we know we have have two setcc instructions
1595 // comparing a value against two constants and or'ing the result
1596 // together. Because of the above check, we know that we only have
1597 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1598 // FoldSetCCLogical check above), that the two constants are not
1600 assert(LHSCst != RHSCst && "Compares not folded above?");
1603 default: assert(0 && "Unknown integer condition code!");
1604 case Instruction::SetEQ:
1606 default: assert(0 && "Unknown integer condition code!");
1607 case Instruction::SetEQ:
1608 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
1609 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1610 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
1611 LHSVal->getName()+".off");
1612 InsertNewInstBefore(Add, I);
1613 const Type *UnsType = Add->getType()->getUnsignedVersion();
1614 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
1615 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
1616 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1617 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1619 break; // (X == 13 | X == 15) -> no change
1621 case Instruction::SetGT:
1622 if (LHSCst == SubOne(RHSCst)) // (X == 13 | X > 14) -> X > 13
1623 return new SetCondInst(Instruction::SetGT, LHSVal, LHSCst);
1624 break; // (X == 13 | X > 15) -> no change
1625 case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
1626 case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
1627 return ReplaceInstUsesWith(I, RHS);
1630 case Instruction::SetNE:
1632 default: assert(0 && "Unknown integer condition code!");
1633 case Instruction::SetLT: // (X != 13 | X < 15) -> X < 15
1634 return ReplaceInstUsesWith(I, RHS);
1635 case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
1636 case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
1637 return ReplaceInstUsesWith(I, LHS);
1638 case Instruction::SetNE: // (X != 13 | X != 15) -> true
1639 return ReplaceInstUsesWith(I, ConstantBool::True);
1642 case Instruction::SetLT:
1644 default: assert(0 && "Unknown integer condition code!");
1645 case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
1647 case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
1648 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
1649 case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
1650 case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
1651 return ReplaceInstUsesWith(I, RHS);
1654 case Instruction::SetGT:
1656 default: assert(0 && "Unknown integer condition code!");
1657 case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
1658 case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
1659 return ReplaceInstUsesWith(I, LHS);
1660 case Instruction::SetNE: // (X > 13 | X != 15) -> true
1661 case Instruction::SetLT: // (X > 13 | X < 15) -> true
1662 return ReplaceInstUsesWith(I, ConstantBool::True);
1667 return Changed ? &I : 0;
1670 // XorSelf - Implements: X ^ X --> 0
1673 XorSelf(Value *rhs) : RHS(rhs) {}
1674 bool shouldApply(Value *LHS) const { return LHS == RHS; }
1675 Instruction *apply(BinaryOperator &Xor) const {
1681 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
1682 bool Changed = SimplifyCommutative(I);
1683 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1685 if (isa<UndefValue>(Op1))
1686 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
1688 // xor X, X = 0, even if X is nested in a sequence of Xor's.
1689 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
1690 assert(Result == &I && "AssociativeOpt didn't work?");
1691 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1694 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1696 if (RHS->isNullValue())
1697 return ReplaceInstUsesWith(I, Op0);
1699 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
1700 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
1701 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
1702 if (RHS == ConstantBool::True && SCI->hasOneUse())
1703 return new SetCondInst(SCI->getInverseCondition(),
1704 SCI->getOperand(0), SCI->getOperand(1));
1706 // ~(c-X) == X-c-1 == X+(-c-1)
1707 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
1708 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
1709 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
1710 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
1711 ConstantInt::get(I.getType(), 1));
1712 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
1715 // ~(~X & Y) --> (X | ~Y)
1716 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
1717 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
1718 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
1720 BinaryOperator::createNot(Op0I->getOperand(1),
1721 Op0I->getOperand(1)->getName()+".not");
1722 InsertNewInstBefore(NotY, I);
1723 return BinaryOperator::createOr(Op0NotVal, NotY);
1727 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1728 switch (Op0I->getOpcode()) {
1729 case Instruction::Add:
1730 // ~(X-c) --> (-c-1)-X
1731 if (RHS->isAllOnesValue()) {
1732 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
1733 return BinaryOperator::createSub(
1734 ConstantExpr::getSub(NegOp0CI,
1735 ConstantInt::get(I.getType(), 1)),
1736 Op0I->getOperand(0));
1739 case Instruction::And:
1740 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
1741 if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue())
1742 return BinaryOperator::createOr(Op0, RHS);
1744 case Instruction::Or:
1745 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
1746 if (ConstantExpr::getAnd(RHS, Op0CI) == RHS)
1747 return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS));
1753 // Try to fold constant and into select arguments.
1754 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1755 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1757 if (isa<PHINode>(Op0))
1758 if (Instruction *NV = FoldOpIntoPhi(I))
1762 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
1764 return ReplaceInstUsesWith(I,
1765 ConstantIntegral::getAllOnesValue(I.getType()));
1767 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
1769 return ReplaceInstUsesWith(I,
1770 ConstantIntegral::getAllOnesValue(I.getType()));
1772 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
1773 if (Op1I->getOpcode() == Instruction::Or) {
1774 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
1775 cast<BinaryOperator>(Op1I)->swapOperands();
1777 std::swap(Op0, Op1);
1778 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
1780 std::swap(Op0, Op1);
1782 } else if (Op1I->getOpcode() == Instruction::Xor) {
1783 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
1784 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
1785 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
1786 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
1789 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
1790 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
1791 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
1792 cast<BinaryOperator>(Op0I)->swapOperands();
1793 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
1794 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
1795 Op1->getName()+".not"), I);
1796 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
1798 } else if (Op0I->getOpcode() == Instruction::Xor) {
1799 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
1800 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
1801 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
1802 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
1805 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
1806 Value *A, *B; ConstantInt *C1, *C2;
1807 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
1808 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) &&
1809 ConstantExpr::getAnd(C1, C2)->isNullValue())
1810 return BinaryOperator::createOr(Op0, Op1);
1812 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
1813 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
1814 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1817 return Changed ? &I : 0;
1820 /// MulWithOverflow - Compute Result = In1*In2, returning true if the result
1821 /// overflowed for this type.
1822 static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
1824 Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
1825 return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
1828 static bool isPositive(ConstantInt *C) {
1829 return cast<ConstantSInt>(C)->getValue() >= 0;
1832 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
1833 /// overflowed for this type.
1834 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
1836 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
1838 if (In1->getType()->isUnsigned())
1839 return cast<ConstantUInt>(Result)->getValue() <
1840 cast<ConstantUInt>(In1)->getValue();
1841 if (isPositive(In1) != isPositive(In2))
1843 if (isPositive(In1))
1844 return cast<ConstantSInt>(Result)->getValue() <
1845 cast<ConstantSInt>(In1)->getValue();
1846 return cast<ConstantSInt>(Result)->getValue() >
1847 cast<ConstantSInt>(In1)->getValue();
1850 Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
1851 bool Changed = SimplifyCommutative(I);
1852 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1853 const Type *Ty = Op0->getType();
1857 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
1859 if (isa<UndefValue>(Op1)) // X setcc undef -> undef
1860 return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
1862 // setcc <global/alloca*>, 0 - Global/Stack value addresses are never null!
1863 if (isa<ConstantPointerNull>(Op1) &&
1864 (isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0)))
1865 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
1868 // setcc's with boolean values can always be turned into bitwise operations
1869 if (Ty == Type::BoolTy) {
1870 switch (I.getOpcode()) {
1871 default: assert(0 && "Invalid setcc instruction!");
1872 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
1873 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
1874 InsertNewInstBefore(Xor, I);
1875 return BinaryOperator::createNot(Xor);
1877 case Instruction::SetNE:
1878 return BinaryOperator::createXor(Op0, Op1);
1880 case Instruction::SetGT:
1881 std::swap(Op0, Op1); // Change setgt -> setlt
1883 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
1884 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
1885 InsertNewInstBefore(Not, I);
1886 return BinaryOperator::createAnd(Not, Op1);
1888 case Instruction::SetGE:
1889 std::swap(Op0, Op1); // Change setge -> setle
1891 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
1892 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
1893 InsertNewInstBefore(Not, I);
1894 return BinaryOperator::createOr(Not, Op1);
1899 // See if we are doing a comparison between a constant and an instruction that
1900 // can be folded into the comparison.
1901 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
1902 // Check to see if we are comparing against the minimum or maximum value...
1903 if (CI->isMinValue()) {
1904 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
1905 return ReplaceInstUsesWith(I, ConstantBool::False);
1906 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
1907 return ReplaceInstUsesWith(I, ConstantBool::True);
1908 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
1909 return BinaryOperator::createSetEQ(Op0, Op1);
1910 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
1911 return BinaryOperator::createSetNE(Op0, Op1);
1913 } else if (CI->isMaxValue()) {
1914 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
1915 return ReplaceInstUsesWith(I, ConstantBool::False);
1916 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
1917 return ReplaceInstUsesWith(I, ConstantBool::True);
1918 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
1919 return BinaryOperator::createSetEQ(Op0, Op1);
1920 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
1921 return BinaryOperator::createSetNE(Op0, Op1);
1923 // Comparing against a value really close to min or max?
1924 } else if (isMinValuePlusOne(CI)) {
1925 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
1926 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
1927 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
1928 return BinaryOperator::createSetNE(Op0, SubOne(CI));
1930 } else if (isMaxValueMinusOne(CI)) {
1931 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
1932 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
1933 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
1934 return BinaryOperator::createSetNE(Op0, AddOne(CI));
1937 // If we still have a setle or setge instruction, turn it into the
1938 // appropriate setlt or setgt instruction. Since the border cases have
1939 // already been handled above, this requires little checking.
1941 if (I.getOpcode() == Instruction::SetLE)
1942 return BinaryOperator::createSetLT(Op0, AddOne(CI));
1943 if (I.getOpcode() == Instruction::SetGE)
1944 return BinaryOperator::createSetGT(Op0, SubOne(CI));
1946 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
1947 switch (LHSI->getOpcode()) {
1948 case Instruction::PHI:
1949 if (Instruction *NV = FoldOpIntoPhi(I))
1952 case Instruction::And:
1953 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
1954 LHSI->getOperand(0)->hasOneUse()) {
1955 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
1956 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
1957 // happens a LOT in code produced by the C front-end, for bitfield
1959 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
1960 ConstantUInt *ShAmt;
1961 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
1962 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
1963 const Type *Ty = LHSI->getType();
1965 // We can fold this as long as we can't shift unknown bits
1966 // into the mask. This can only happen with signed shift
1967 // rights, as they sign-extend.
1969 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
1970 Shift->getType()->isUnsigned();
1972 // To test for the bad case of the signed shr, see if any
1973 // of the bits shifted in could be tested after the mask.
1974 Constant *OShAmt = ConstantUInt::get(Type::UByteTy,
1975 Ty->getPrimitiveSize()*8-ShAmt->getValue());
1977 ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
1978 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
1984 if (Shift->getOpcode() == Instruction::Shl)
1985 NewCst = ConstantExpr::getUShr(CI, ShAmt);
1987 NewCst = ConstantExpr::getShl(CI, ShAmt);
1989 // Check to see if we are shifting out any of the bits being
1991 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
1992 // If we shifted bits out, the fold is not going to work out.
1993 // As a special case, check to see if this means that the
1994 // result is always true or false now.
1995 if (I.getOpcode() == Instruction::SetEQ)
1996 return ReplaceInstUsesWith(I, ConstantBool::False);
1997 if (I.getOpcode() == Instruction::SetNE)
1998 return ReplaceInstUsesWith(I, ConstantBool::True);
2000 I.setOperand(1, NewCst);
2001 Constant *NewAndCST;
2002 if (Shift->getOpcode() == Instruction::Shl)
2003 NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
2005 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
2006 LHSI->setOperand(1, NewAndCST);
2007 LHSI->setOperand(0, Shift->getOperand(0));
2008 WorkList.push_back(Shift); // Shift is dead.
2009 AddUsesToWorkList(I);
2017 case Instruction::Cast: { // (setcc (cast X to larger), CI)
2018 const Type *SrcTy = LHSI->getOperand(0)->getType();
2019 if (SrcTy->isIntegral() && LHSI->getType()->isIntegral()) {
2020 unsigned SrcBits = SrcTy->getPrimitiveSize()*8;
2021 if (SrcTy == Type::BoolTy) SrcBits = 1;
2022 unsigned DestBits = LHSI->getType()->getPrimitiveSize()*8;
2023 if (LHSI->getType() == Type::BoolTy) DestBits = 1;
2024 if (SrcBits < DestBits) {
2025 // Check to see if the comparison is always true or false.
2026 Constant *NewCst = ConstantExpr::getCast(CI, SrcTy);
2027 if (ConstantExpr::getCast(NewCst, LHSI->getType()) != CI) {
2028 Constant *Min = ConstantIntegral::getMinValue(SrcTy);
2029 Constant *Max = ConstantIntegral::getMaxValue(SrcTy);
2030 Min = ConstantExpr::getCast(Min, LHSI->getType());
2031 Max = ConstantExpr::getCast(Max, LHSI->getType());
2032 switch (I.getOpcode()) {
2033 default: assert(0 && "unknown integer comparison");
2034 case Instruction::SetEQ:
2035 return ReplaceInstUsesWith(I, ConstantBool::False);
2036 case Instruction::SetNE:
2037 return ReplaceInstUsesWith(I, ConstantBool::True);
2038 case Instruction::SetLT:
2039 return ReplaceInstUsesWith(I, ConstantExpr::getSetLT(Max, CI));
2040 case Instruction::SetGT:
2041 return ReplaceInstUsesWith(I, ConstantExpr::getSetGT(Min, CI));
2045 return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),
2046 ConstantExpr::getCast(CI, SrcTy));
2051 case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
2052 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2053 switch (I.getOpcode()) {
2055 case Instruction::SetEQ:
2056 case Instruction::SetNE: {
2057 // If we are comparing against bits always shifted out, the
2058 // comparison cannot succeed.
2060 ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
2061 if (Comp != CI) {// Comparing against a bit that we know is zero.
2062 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2063 Constant *Cst = ConstantBool::get(IsSetNE);
2064 return ReplaceInstUsesWith(I, Cst);
2067 if (LHSI->hasOneUse()) {
2068 // Otherwise strength reduce the shift into an and.
2069 unsigned ShAmtVal = ShAmt->getValue();
2070 unsigned TypeBits = CI->getType()->getPrimitiveSize()*8;
2071 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
2074 if (CI->getType()->isUnsigned()) {
2075 Mask = ConstantUInt::get(CI->getType(), Val);
2076 } else if (ShAmtVal != 0) {
2077 Mask = ConstantSInt::get(CI->getType(), Val);
2079 Mask = ConstantInt::getAllOnesValue(CI->getType());
2083 BinaryOperator::createAnd(LHSI->getOperand(0),
2084 Mask, LHSI->getName()+".mask");
2085 Value *And = InsertNewInstBefore(AndI, I);
2086 return new SetCondInst(I.getOpcode(), And,
2087 ConstantExpr::getUShr(CI, ShAmt));
2094 case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
2095 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2096 switch (I.getOpcode()) {
2098 case Instruction::SetEQ:
2099 case Instruction::SetNE: {
2100 // If we are comparing against bits always shifted out, the
2101 // comparison cannot succeed.
2103 ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
2105 if (Comp != CI) {// Comparing against a bit that we know is zero.
2106 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2107 Constant *Cst = ConstantBool::get(IsSetNE);
2108 return ReplaceInstUsesWith(I, Cst);
2111 if (LHSI->hasOneUse() || CI->isNullValue()) {
2112 unsigned ShAmtVal = ShAmt->getValue();
2114 // Otherwise strength reduce the shift into an and.
2115 uint64_t Val = ~0ULL; // All ones.
2116 Val <<= ShAmtVal; // Shift over to the right spot.
2119 if (CI->getType()->isUnsigned()) {
2120 unsigned TypeBits = CI->getType()->getPrimitiveSize()*8;
2121 Val &= (1ULL << TypeBits)-1;
2122 Mask = ConstantUInt::get(CI->getType(), Val);
2124 Mask = ConstantSInt::get(CI->getType(), Val);
2128 BinaryOperator::createAnd(LHSI->getOperand(0),
2129 Mask, LHSI->getName()+".mask");
2130 Value *And = InsertNewInstBefore(AndI, I);
2131 return new SetCondInst(I.getOpcode(), And,
2132 ConstantExpr::getShl(CI, ShAmt));
2140 case Instruction::Div:
2141 // Fold: (div X, C1) op C2 -> range check
2142 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
2143 // Fold this div into the comparison, producing a range check.
2144 // Determine, based on the divide type, what the range is being
2145 // checked. If there is an overflow on the low or high side, remember
2146 // it, otherwise compute the range [low, hi) bounding the new value.
2147 bool LoOverflow = false, HiOverflow = 0;
2148 ConstantInt *LoBound = 0, *HiBound = 0;
2151 bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
2153 Instruction::BinaryOps Opcode = I.getOpcode();
2155 if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
2156 } else if (LHSI->getType()->isUnsigned()) { // udiv
2158 LoOverflow = ProdOV;
2159 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
2160 } else if (isPositive(DivRHS)) { // Divisor is > 0.
2161 if (CI->isNullValue()) { // (X / pos) op 0
2163 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
2165 } else if (isPositive(CI)) { // (X / pos) op pos
2167 LoOverflow = ProdOV;
2168 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
2169 } else { // (X / pos) op neg
2170 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
2171 LoOverflow = AddWithOverflow(LoBound, Prod,
2172 cast<ConstantInt>(DivRHSH));
2174 HiOverflow = ProdOV;
2176 } else { // Divisor is < 0.
2177 if (CI->isNullValue()) { // (X / neg) op 0
2178 LoBound = AddOne(DivRHS);
2179 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
2180 } else if (isPositive(CI)) { // (X / neg) op pos
2181 HiOverflow = LoOverflow = ProdOV;
2183 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
2184 HiBound = AddOne(Prod);
2185 } else { // (X / neg) op neg
2187 LoOverflow = HiOverflow = ProdOV;
2188 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
2191 // Dividing by a negate swaps the condition.
2192 Opcode = SetCondInst::getSwappedCondition(Opcode);
2196 Value *X = LHSI->getOperand(0);
2198 default: assert(0 && "Unhandled setcc opcode!");
2199 case Instruction::SetEQ:
2200 if (LoOverflow && HiOverflow)
2201 return ReplaceInstUsesWith(I, ConstantBool::False);
2202 else if (HiOverflow)
2203 return new SetCondInst(Instruction::SetGE, X, LoBound);
2204 else if (LoOverflow)
2205 return new SetCondInst(Instruction::SetLT, X, HiBound);
2207 return InsertRangeTest(X, LoBound, HiBound, true, I);
2208 case Instruction::SetNE:
2209 if (LoOverflow && HiOverflow)
2210 return ReplaceInstUsesWith(I, ConstantBool::True);
2211 else if (HiOverflow)
2212 return new SetCondInst(Instruction::SetLT, X, LoBound);
2213 else if (LoOverflow)
2214 return new SetCondInst(Instruction::SetGE, X, HiBound);
2216 return InsertRangeTest(X, LoBound, HiBound, false, I);
2217 case Instruction::SetLT:
2219 return ReplaceInstUsesWith(I, ConstantBool::False);
2220 return new SetCondInst(Instruction::SetLT, X, LoBound);
2221 case Instruction::SetGT:
2223 return ReplaceInstUsesWith(I, ConstantBool::False);
2224 return new SetCondInst(Instruction::SetGE, X, HiBound);
2229 case Instruction::Select:
2230 // If either operand of the select is a constant, we can fold the
2231 // comparison into the select arms, which will cause one to be
2232 // constant folded and the select turned into a bitwise or.
2233 Value *Op1 = 0, *Op2 = 0;
2234 if (LHSI->hasOneUse()) {
2235 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
2236 // Fold the known value into the constant operand.
2237 Op1 = ConstantExpr::get(I.getOpcode(), C, CI);
2238 // Insert a new SetCC of the other select operand.
2239 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
2240 LHSI->getOperand(2), CI,
2242 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
2243 // Fold the known value into the constant operand.
2244 Op2 = ConstantExpr::get(I.getOpcode(), C, CI);
2245 // Insert a new SetCC of the other select operand.
2246 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
2247 LHSI->getOperand(1), CI,
2253 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
2257 // Simplify seteq and setne instructions...
2258 if (I.getOpcode() == Instruction::SetEQ ||
2259 I.getOpcode() == Instruction::SetNE) {
2260 bool isSetNE = I.getOpcode() == Instruction::SetNE;
2262 // If the first operand is (and|or|xor) with a constant, and the second
2263 // operand is a constant, simplify a bit.
2264 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
2265 switch (BO->getOpcode()) {
2266 case Instruction::Rem:
2267 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
2268 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
2270 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1)
2272 Log2(cast<ConstantSInt>(BO->getOperand(1))->getValue())) {
2273 const Type *UTy = BO->getType()->getUnsignedVersion();
2274 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
2276 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
2277 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
2278 RHSCst, BO->getName()), I);
2279 return BinaryOperator::create(I.getOpcode(), NewRem,
2280 Constant::getNullValue(UTy));
2284 case Instruction::Add:
2285 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
2286 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2287 if (BO->hasOneUse())
2288 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
2289 ConstantExpr::getSub(CI, BOp1C));
2290 } else if (CI->isNullValue()) {
2291 // Replace ((add A, B) != 0) with (A != -B) if A or B is
2292 // efficiently invertible, or if the add has just this one use.
2293 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
2295 if (Value *NegVal = dyn_castNegVal(BOp1))
2296 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
2297 else if (Value *NegVal = dyn_castNegVal(BOp0))
2298 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
2299 else if (BO->hasOneUse()) {
2300 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
2302 InsertNewInstBefore(Neg, I);
2303 return new SetCondInst(I.getOpcode(), BOp0, Neg);
2307 case Instruction::Xor:
2308 // For the xor case, we can xor two constants together, eliminating
2309 // the explicit xor.
2310 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
2311 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
2312 ConstantExpr::getXor(CI, BOC));
2315 case Instruction::Sub:
2316 // Replace (([sub|xor] A, B) != 0) with (A != B)
2317 if (CI->isNullValue())
2318 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
2322 case Instruction::Or:
2323 // If bits are being or'd in that are not present in the constant we
2324 // are comparing against, then the comparison could never succeed!
2325 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
2326 Constant *NotCI = ConstantExpr::getNot(CI);
2327 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
2328 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
2332 case Instruction::And:
2333 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2334 // If bits are being compared against that are and'd out, then the
2335 // comparison can never succeed!
2336 if (!ConstantExpr::getAnd(CI,
2337 ConstantExpr::getNot(BOC))->isNullValue())
2338 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
2340 // If we have ((X & C) == C), turn it into ((X & C) != 0).
2341 if (CI == BOC && isOneBitSet(CI))
2342 return new SetCondInst(isSetNE ? Instruction::SetEQ :
2343 Instruction::SetNE, Op0,
2344 Constant::getNullValue(CI->getType()));
2346 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
2347 // to be a signed value as appropriate.
2348 if (isSignBit(BOC)) {
2349 Value *X = BO->getOperand(0);
2350 // If 'X' is not signed, insert a cast now...
2351 if (!BOC->getType()->isSigned()) {
2352 const Type *DestTy = BOC->getType()->getSignedVersion();
2353 X = InsertCastBefore(X, DestTy, I);
2355 return new SetCondInst(isSetNE ? Instruction::SetLT :
2356 Instruction::SetGE, X,
2357 Constant::getNullValue(X->getType()));
2360 // ((X & ~7) == 0) --> X < 8
2361 if (CI->isNullValue() && isHighOnes(BOC)) {
2362 Value *X = BO->getOperand(0);
2363 Constant *NegX = ConstantExpr::getNeg(BOC);
2365 // If 'X' is signed, insert a cast now.
2366 if (NegX->getType()->isSigned()) {
2367 const Type *DestTy = NegX->getType()->getUnsignedVersion();
2368 X = InsertCastBefore(X, DestTy, I);
2369 NegX = ConstantExpr::getCast(NegX, DestTy);
2372 return new SetCondInst(isSetNE ? Instruction::SetGE :
2373 Instruction::SetLT, X, NegX);
2380 } else { // Not a SetEQ/SetNE
2381 // If the LHS is a cast from an integral value of the same size,
2382 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
2383 Value *CastOp = Cast->getOperand(0);
2384 const Type *SrcTy = CastOp->getType();
2385 unsigned SrcTySize = SrcTy->getPrimitiveSize();
2386 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
2387 SrcTySize == Cast->getType()->getPrimitiveSize()) {
2388 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
2389 "Source and destination signednesses should differ!");
2390 if (Cast->getType()->isSigned()) {
2391 // If this is a signed comparison, check for comparisons in the
2392 // vicinity of zero.
2393 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
2395 return BinaryOperator::createSetGT(CastOp,
2396 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize*8-1))-1));
2397 else if (I.getOpcode() == Instruction::SetGT &&
2398 cast<ConstantSInt>(CI)->getValue() == -1)
2399 // X > -1 => x < 128
2400 return BinaryOperator::createSetLT(CastOp,
2401 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize*8-1)));
2403 ConstantUInt *CUI = cast<ConstantUInt>(CI);
2404 if (I.getOpcode() == Instruction::SetLT &&
2405 CUI->getValue() == 1ULL << (SrcTySize*8-1))
2406 // X < 128 => X > -1
2407 return BinaryOperator::createSetGT(CastOp,
2408 ConstantSInt::get(SrcTy, -1));
2409 else if (I.getOpcode() == Instruction::SetGT &&
2410 CUI->getValue() == (1ULL << (SrcTySize*8-1))-1)
2412 return BinaryOperator::createSetLT(CastOp,
2413 Constant::getNullValue(SrcTy));
2420 // Test to see if the operands of the setcc are casted versions of other
2421 // values. If the cast can be stripped off both arguments, we do so now.
2422 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
2423 Value *CastOp0 = CI->getOperand(0);
2424 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
2425 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
2426 (I.getOpcode() == Instruction::SetEQ ||
2427 I.getOpcode() == Instruction::SetNE)) {
2428 // We keep moving the cast from the left operand over to the right
2429 // operand, where it can often be eliminated completely.
2432 // If operand #1 is a cast instruction, see if we can eliminate it as
2434 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
2435 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
2437 Op1 = CI2->getOperand(0);
2439 // If Op1 is a constant, we can fold the cast into the constant.
2440 if (Op1->getType() != Op0->getType())
2441 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
2442 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
2444 // Otherwise, cast the RHS right before the setcc
2445 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
2446 InsertNewInstBefore(cast<Instruction>(Op1), I);
2448 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
2451 // Handle the special case of: setcc (cast bool to X), <cst>
2452 // This comes up when you have code like
2455 // For generality, we handle any zero-extension of any operand comparison
2457 if (ConstantInt *ConstantRHS = dyn_cast<ConstantInt>(Op1)) {
2458 const Type *SrcTy = CastOp0->getType();
2459 const Type *DestTy = Op0->getType();
2460 if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
2461 (SrcTy->isUnsigned() || SrcTy == Type::BoolTy)) {
2462 // Ok, we have an expansion of operand 0 into a new type. Get the
2463 // constant value, masink off bits which are not set in the RHS. These
2464 // could be set if the destination value is signed.
2465 uint64_t ConstVal = ConstantRHS->getRawValue();
2466 ConstVal &= (1ULL << DestTy->getPrimitiveSize()*8)-1;
2468 // If the constant we are comparing it with has high bits set, which
2469 // don't exist in the original value, the values could never be equal,
2470 // because the source would be zero extended.
2472 SrcTy == Type::BoolTy ? 1 : SrcTy->getPrimitiveSize()*8;
2473 bool HasSignBit = ConstVal & (1ULL << (DestTy->getPrimitiveSize()*8-1));
2474 if (ConstVal & ~((1ULL << SrcBits)-1)) {
2475 switch (I.getOpcode()) {
2476 default: assert(0 && "Unknown comparison type!");
2477 case Instruction::SetEQ:
2478 return ReplaceInstUsesWith(I, ConstantBool::False);
2479 case Instruction::SetNE:
2480 return ReplaceInstUsesWith(I, ConstantBool::True);
2481 case Instruction::SetLT:
2482 case Instruction::SetLE:
2483 if (DestTy->isSigned() && HasSignBit)
2484 return ReplaceInstUsesWith(I, ConstantBool::False);
2485 return ReplaceInstUsesWith(I, ConstantBool::True);
2486 case Instruction::SetGT:
2487 case Instruction::SetGE:
2488 if (DestTy->isSigned() && HasSignBit)
2489 return ReplaceInstUsesWith(I, ConstantBool::True);
2490 return ReplaceInstUsesWith(I, ConstantBool::False);
2494 // Otherwise, we can replace the setcc with a setcc of the smaller
2496 Op1 = ConstantExpr::getCast(cast<Constant>(Op1), SrcTy);
2497 return BinaryOperator::create(I.getOpcode(), CastOp0, Op1);
2501 return Changed ? &I : 0;
2506 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
2507 assert(I.getOperand(1)->getType() == Type::UByteTy);
2508 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2509 bool isLeftShift = I.getOpcode() == Instruction::Shl;
2511 // shl X, 0 == X and shr X, 0 == X
2512 // shl 0, X == 0 and shr 0, X == 0
2513 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
2514 Op0 == Constant::getNullValue(Op0->getType()))
2515 return ReplaceInstUsesWith(I, Op0);
2517 if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
2518 if (!isLeftShift && I.getType()->isSigned())
2519 return ReplaceInstUsesWith(I, Op1);
2520 else // undef << X -> 0 AND undef >>u X -> 0
2521 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2523 if (isa<UndefValue>(Op1)) {
2524 if (isLeftShift || I.getType()->isUnsigned())
2525 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2527 return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X
2530 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
2532 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
2533 if (CSI->isAllOnesValue())
2534 return ReplaceInstUsesWith(I, CSI);
2536 // Try to fold constant and into select arguments.
2537 if (isa<Constant>(Op0))
2538 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
2539 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
2542 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
2543 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
2544 // of a signed value.
2546 unsigned TypeBits = Op0->getType()->getPrimitiveSize()*8;
2547 if (CUI->getValue() >= TypeBits) {
2548 if (!Op0->getType()->isSigned() || isLeftShift)
2549 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
2551 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
2556 // ((X*C1) << C2) == (X * (C1 << C2))
2557 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
2558 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
2559 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
2560 return BinaryOperator::createMul(BO->getOperand(0),
2561 ConstantExpr::getShl(BOOp, CUI));
2563 // Try to fold constant and into select arguments.
2564 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2565 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
2567 if (isa<PHINode>(Op0))
2568 if (Instruction *NV = FoldOpIntoPhi(I))
2571 // If the operand is an bitwise operator with a constant RHS, and the
2572 // shift is the only use, we can pull it out of the shift.
2573 if (Op0->hasOneUse())
2574 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0))
2575 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
2576 bool isValid = true; // Valid only for And, Or, Xor
2577 bool highBitSet = false; // Transform if high bit of constant set?
2579 switch (Op0BO->getOpcode()) {
2580 default: isValid = false; break; // Do not perform transform!
2581 case Instruction::Add:
2582 isValid = isLeftShift;
2584 case Instruction::Or:
2585 case Instruction::Xor:
2588 case Instruction::And:
2593 // If this is a signed shift right, and the high bit is modified
2594 // by the logical operation, do not perform the transformation.
2595 // The highBitSet boolean indicates the value of the high bit of
2596 // the constant which would cause it to be modified for this
2599 if (isValid && !isLeftShift && !I.getType()->isUnsigned()) {
2600 uint64_t Val = Op0C->getRawValue();
2601 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
2605 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI);
2607 Instruction *NewShift =
2608 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI,
2611 InsertNewInstBefore(NewShift, I);
2613 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
2618 // If this is a shift of a shift, see if we can fold the two together...
2619 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
2620 if (ConstantUInt *ShiftAmt1C =
2621 dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) {
2622 unsigned ShiftAmt1 = ShiftAmt1C->getValue();
2623 unsigned ShiftAmt2 = CUI->getValue();
2625 // Check for (A << c1) << c2 and (A >> c1) >> c2
2626 if (I.getOpcode() == Op0SI->getOpcode()) {
2627 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
2628 if (Op0->getType()->getPrimitiveSize()*8 < Amt)
2629 Amt = Op0->getType()->getPrimitiveSize()*8;
2630 return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
2631 ConstantUInt::get(Type::UByteTy, Amt));
2634 // Check for (A << c1) >> c2 or visaversa. If we are dealing with
2635 // signed types, we can only support the (A >> c1) << c2 configuration,
2636 // because it can not turn an arbitrary bit of A into a sign bit.
2637 if (I.getType()->isUnsigned() || isLeftShift) {
2638 // Calculate bitmask for what gets shifted off the edge...
2639 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
2641 C = ConstantExpr::getShl(C, ShiftAmt1C);
2643 C = ConstantExpr::getShr(C, ShiftAmt1C);
2646 BinaryOperator::createAnd(Op0SI->getOperand(0), C,
2647 Op0SI->getOperand(0)->getName()+".mask");
2648 InsertNewInstBefore(Mask, I);
2650 // Figure out what flavor of shift we should use...
2651 if (ShiftAmt1 == ShiftAmt2)
2652 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
2653 else if (ShiftAmt1 < ShiftAmt2) {
2654 return new ShiftInst(I.getOpcode(), Mask,
2655 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
2657 return new ShiftInst(Op0SI->getOpcode(), Mask,
2658 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
2674 /// getCastType - In the future, we will split the cast instruction into these
2675 /// various types. Until then, we have to do the analysis here.
2676 static CastType getCastType(const Type *Src, const Type *Dest) {
2677 assert(Src->isIntegral() && Dest->isIntegral() &&
2678 "Only works on integral types!");
2679 unsigned SrcSize = Src->getPrimitiveSize()*8;
2680 if (Src == Type::BoolTy) SrcSize = 1;
2681 unsigned DestSize = Dest->getPrimitiveSize()*8;
2682 if (Dest == Type::BoolTy) DestSize = 1;
2684 if (SrcSize == DestSize) return Noop;
2685 if (SrcSize > DestSize) return Truncate;
2686 if (Src->isSigned()) return Signext;
2691 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
2694 static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
2695 const Type *DstTy, TargetData *TD) {
2697 // It is legal to eliminate the instruction if casting A->B->A if the sizes
2698 // are identical and the bits don't get reinterpreted (for example
2699 // int->float->int would not be allowed).
2700 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
2703 // If we are casting between pointer and integer types, treat pointers as
2704 // integers of the appropriate size for the code below.
2705 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
2706 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
2707 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
2709 // Allow free casting and conversion of sizes as long as the sign doesn't
2711 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
2712 CastType FirstCast = getCastType(SrcTy, MidTy);
2713 CastType SecondCast = getCastType(MidTy, DstTy);
2715 // Capture the effect of these two casts. If the result is a legal cast,
2716 // the CastType is stored here, otherwise a special code is used.
2717 static const unsigned CastResult[] = {
2718 // First cast is noop
2720 // First cast is a truncate
2721 1, 1, 4, 4, // trunc->extend is not safe to eliminate
2722 // First cast is a sign ext
2723 2, 5, 2, 4, // signext->zeroext never ok
2724 // First cast is a zero ext
2728 unsigned Result = CastResult[FirstCast*4+SecondCast];
2730 default: assert(0 && "Illegal table value!");
2735 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
2736 // truncates, we could eliminate more casts.
2737 return (unsigned)getCastType(SrcTy, DstTy) == Result;
2739 return false; // Not possible to eliminate this here.
2741 // Sign or zero extend followed by truncate is always ok if the result
2742 // is a truncate or noop.
2743 CastType ResultCast = getCastType(SrcTy, DstTy);
2744 if (ResultCast == Noop || ResultCast == Truncate)
2746 // Otherwise we are still growing the value, we are only safe if the
2747 // result will match the sign/zeroextendness of the result.
2748 return ResultCast == FirstCast;
2754 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
2755 if (V->getType() == Ty || isa<Constant>(V)) return false;
2756 if (const CastInst *CI = dyn_cast<CastInst>(V))
2757 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
2763 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
2764 /// InsertBefore instruction. This is specialized a bit to avoid inserting
2765 /// casts that are known to not do anything...
2767 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
2768 Instruction *InsertBefore) {
2769 if (V->getType() == DestTy) return V;
2770 if (Constant *C = dyn_cast<Constant>(V))
2771 return ConstantExpr::getCast(C, DestTy);
2773 CastInst *CI = new CastInst(V, DestTy, V->getName());
2774 InsertNewInstBefore(CI, *InsertBefore);
2778 // CastInst simplification
2780 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
2781 Value *Src = CI.getOperand(0);
2783 // If the user is casting a value to the same type, eliminate this cast
2785 if (CI.getType() == Src->getType())
2786 return ReplaceInstUsesWith(CI, Src);
2788 if (isa<UndefValue>(Src)) // cast undef -> undef
2789 return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
2791 // If casting the result of another cast instruction, try to eliminate this
2794 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) {
2795 if (isEliminableCastOfCast(CSrc->getOperand(0)->getType(),
2796 CSrc->getType(), CI.getType(), TD)) {
2797 // This instruction now refers directly to the cast's src operand. This
2798 // has a good chance of making CSrc dead.
2799 CI.setOperand(0, CSrc->getOperand(0));
2803 // If this is an A->B->A cast, and we are dealing with integral types, try
2804 // to convert this into a logical 'and' instruction.
2806 if (CSrc->getOperand(0)->getType() == CI.getType() &&
2807 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
2808 CI.getType()->isUnsigned() && CSrc->getType()->isUnsigned() &&
2809 CSrc->getType()->getPrimitiveSize() < CI.getType()->getPrimitiveSize()){
2810 assert(CSrc->getType() != Type::ULongTy &&
2811 "Cannot have type bigger than ulong!");
2812 uint64_t AndValue = (1ULL << CSrc->getType()->getPrimitiveSize()*8)-1;
2813 Constant *AndOp = ConstantUInt::get(CI.getType(), AndValue);
2814 return BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
2818 // If this is a cast to bool, turn it into the appropriate setne instruction.
2819 if (CI.getType() == Type::BoolTy)
2820 return BinaryOperator::createSetNE(CI.getOperand(0),
2821 Constant::getNullValue(CI.getOperand(0)->getType()));
2823 // If casting the result of a getelementptr instruction with no offset, turn
2824 // this into a cast of the original pointer!
2826 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
2827 bool AllZeroOperands = true;
2828 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
2829 if (!isa<Constant>(GEP->getOperand(i)) ||
2830 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
2831 AllZeroOperands = false;
2834 if (AllZeroOperands) {
2835 CI.setOperand(0, GEP->getOperand(0));
2840 // If we are casting a malloc or alloca to a pointer to a type of the same
2841 // size, rewrite the allocation instruction to allocate the "right" type.
2843 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
2844 if (AI->hasOneUse() && !AI->isArrayAllocation())
2845 if (const PointerType *PTy = dyn_cast<PointerType>(CI.getType())) {
2846 // Get the type really allocated and the type casted to...
2847 const Type *AllocElTy = AI->getAllocatedType();
2848 const Type *CastElTy = PTy->getElementType();
2849 if (AllocElTy->isSized() && CastElTy->isSized()) {
2850 unsigned AllocElTySize = TD->getTypeSize(AllocElTy);
2851 unsigned CastElTySize = TD->getTypeSize(CastElTy);
2853 // If the allocation is for an even multiple of the cast type size
2854 if (CastElTySize && (AllocElTySize % CastElTySize == 0)) {
2855 Value *Amt = ConstantUInt::get(Type::UIntTy,
2856 AllocElTySize/CastElTySize);
2857 std::string Name = AI->getName(); AI->setName("");
2858 AllocationInst *New;
2859 if (isa<MallocInst>(AI))
2860 New = new MallocInst(CastElTy, Amt, Name);
2862 New = new AllocaInst(CastElTy, Amt, Name);
2863 InsertNewInstBefore(New, *AI);
2864 return ReplaceInstUsesWith(CI, New);
2869 if (isa<PHINode>(Src))
2870 if (Instruction *NV = FoldOpIntoPhi(CI))
2873 // If the source value is an instruction with only this use, we can attempt to
2874 // propagate the cast into the instruction. Also, only handle integral types
2876 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
2877 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
2878 CI.getType()->isInteger()) { // Don't mess with casts to bool here
2879 const Type *DestTy = CI.getType();
2880 unsigned SrcBitSize = getTypeSizeInBits(Src->getType());
2881 unsigned DestBitSize = getTypeSizeInBits(DestTy);
2883 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
2884 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
2886 switch (SrcI->getOpcode()) {
2887 case Instruction::Add:
2888 case Instruction::Mul:
2889 case Instruction::And:
2890 case Instruction::Or:
2891 case Instruction::Xor:
2892 // If we are discarding information, or just changing the sign, rewrite.
2893 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
2894 // Don't insert two casts if they cannot be eliminated. We allow two
2895 // casts to be inserted if the sizes are the same. This could only be
2896 // converting signedness, which is a noop.
2897 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
2898 !ValueRequiresCast(Op0, DestTy, TD)) {
2899 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
2900 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
2901 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
2902 ->getOpcode(), Op0c, Op1c);
2906 case Instruction::Shl:
2907 // Allow changing the sign of the source operand. Do not allow changing
2908 // the size of the shift, UNLESS the shift amount is a constant. We
2909 // mush not change variable sized shifts to a smaller size, because it
2910 // is undefined to shift more bits out than exist in the value.
2911 if (DestBitSize == SrcBitSize ||
2912 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
2913 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
2914 return new ShiftInst(Instruction::Shl, Op0c, Op1);
2923 /// GetSelectFoldableOperands - We want to turn code that looks like this:
2925 /// %D = select %cond, %C, %A
2927 /// %C = select %cond, %B, 0
2930 /// Assuming that the specified instruction is an operand to the select, return
2931 /// a bitmask indicating which operands of this instruction are foldable if they
2932 /// equal the other incoming value of the select.
2934 static unsigned GetSelectFoldableOperands(Instruction *I) {
2935 switch (I->getOpcode()) {
2936 case Instruction::Add:
2937 case Instruction::Mul:
2938 case Instruction::And:
2939 case Instruction::Or:
2940 case Instruction::Xor:
2941 return 3; // Can fold through either operand.
2942 case Instruction::Sub: // Can only fold on the amount subtracted.
2943 case Instruction::Shl: // Can only fold on the shift amount.
2944 case Instruction::Shr:
2947 return 0; // Cannot fold
2951 /// GetSelectFoldableConstant - For the same transformation as the previous
2952 /// function, return the identity constant that goes into the select.
2953 static Constant *GetSelectFoldableConstant(Instruction *I) {
2954 switch (I->getOpcode()) {
2955 default: assert(0 && "This cannot happen!"); abort();
2956 case Instruction::Add:
2957 case Instruction::Sub:
2958 case Instruction::Or:
2959 case Instruction::Xor:
2960 return Constant::getNullValue(I->getType());
2961 case Instruction::Shl:
2962 case Instruction::Shr:
2963 return Constant::getNullValue(Type::UByteTy);
2964 case Instruction::And:
2965 return ConstantInt::getAllOnesValue(I->getType());
2966 case Instruction::Mul:
2967 return ConstantInt::get(I->getType(), 1);
2971 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
2972 Value *CondVal = SI.getCondition();
2973 Value *TrueVal = SI.getTrueValue();
2974 Value *FalseVal = SI.getFalseValue();
2976 // select true, X, Y -> X
2977 // select false, X, Y -> Y
2978 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
2979 if (C == ConstantBool::True)
2980 return ReplaceInstUsesWith(SI, TrueVal);
2982 assert(C == ConstantBool::False);
2983 return ReplaceInstUsesWith(SI, FalseVal);
2986 // select C, X, X -> X
2987 if (TrueVal == FalseVal)
2988 return ReplaceInstUsesWith(SI, TrueVal);
2990 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
2991 return ReplaceInstUsesWith(SI, FalseVal);
2992 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
2993 return ReplaceInstUsesWith(SI, TrueVal);
2994 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
2995 if (isa<Constant>(TrueVal))
2996 return ReplaceInstUsesWith(SI, TrueVal);
2998 return ReplaceInstUsesWith(SI, FalseVal);
3001 if (SI.getType() == Type::BoolTy)
3002 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
3003 if (C == ConstantBool::True) {
3004 // Change: A = select B, true, C --> A = or B, C
3005 return BinaryOperator::createOr(CondVal, FalseVal);
3007 // Change: A = select B, false, C --> A = and !B, C
3009 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
3010 "not."+CondVal->getName()), SI);
3011 return BinaryOperator::createAnd(NotCond, FalseVal);
3013 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
3014 if (C == ConstantBool::False) {
3015 // Change: A = select B, C, false --> A = and B, C
3016 return BinaryOperator::createAnd(CondVal, TrueVal);
3018 // Change: A = select B, C, true --> A = or !B, C
3020 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
3021 "not."+CondVal->getName()), SI);
3022 return BinaryOperator::createOr(NotCond, TrueVal);
3026 // Selecting between two integer constants?
3027 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
3028 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
3029 // select C, 1, 0 -> cast C to int
3030 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
3031 return new CastInst(CondVal, SI.getType());
3032 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
3033 // select C, 0, 1 -> cast !C to int
3035 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
3036 "not."+CondVal->getName()), SI);
3037 return new CastInst(NotCond, SI.getType());
3040 // If one of the constants is zero (we know they can't both be) and we
3041 // have a setcc instruction with zero, and we have an 'and' with the
3042 // non-constant value, eliminate this whole mess. This corresponds to
3043 // cases like this: ((X & 27) ? 27 : 0)
3044 if (TrueValC->isNullValue() || FalseValC->isNullValue())
3045 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
3046 if ((IC->getOpcode() == Instruction::SetEQ ||
3047 IC->getOpcode() == Instruction::SetNE) &&
3048 isa<ConstantInt>(IC->getOperand(1)) &&
3049 cast<Constant>(IC->getOperand(1))->isNullValue())
3050 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
3051 if (ICA->getOpcode() == Instruction::And &&
3052 isa<ConstantInt>(ICA->getOperand(1)) &&
3053 (ICA->getOperand(1) == TrueValC ||
3054 ICA->getOperand(1) == FalseValC) &&
3055 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
3056 // Okay, now we know that everything is set up, we just don't
3057 // know whether we have a setne or seteq and whether the true or
3058 // false val is the zero.
3059 bool ShouldNotVal = !TrueValC->isNullValue();
3060 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
3063 V = InsertNewInstBefore(BinaryOperator::create(
3064 Instruction::Xor, V, ICA->getOperand(1)), SI);
3065 return ReplaceInstUsesWith(SI, V);
3069 // See if we are selecting two values based on a comparison of the two values.
3070 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
3071 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
3072 // Transform (X == Y) ? X : Y -> Y
3073 if (SCI->getOpcode() == Instruction::SetEQ)
3074 return ReplaceInstUsesWith(SI, FalseVal);
3075 // Transform (X != Y) ? X : Y -> X
3076 if (SCI->getOpcode() == Instruction::SetNE)
3077 return ReplaceInstUsesWith(SI, TrueVal);
3078 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
3080 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
3081 // Transform (X == Y) ? Y : X -> X
3082 if (SCI->getOpcode() == Instruction::SetEQ)
3083 return ReplaceInstUsesWith(SI, FalseVal);
3084 // Transform (X != Y) ? Y : X -> Y
3085 if (SCI->getOpcode() == Instruction::SetNE)
3086 return ReplaceInstUsesWith(SI, TrueVal);
3087 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
3091 // See if we can fold the select into one of our operands.
3092 if (SI.getType()->isInteger()) {
3093 // See the comment above GetSelectFoldableOperands for a description of the
3094 // transformation we are doing here.
3095 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
3096 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
3097 !isa<Constant>(FalseVal))
3098 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
3099 unsigned OpToFold = 0;
3100 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
3102 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
3107 Constant *C = GetSelectFoldableConstant(TVI);
3108 std::string Name = TVI->getName(); TVI->setName("");
3109 Instruction *NewSel =
3110 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
3112 InsertNewInstBefore(NewSel, SI);
3113 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
3114 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
3115 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
3116 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
3118 assert(0 && "Unknown instruction!!");
3123 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
3124 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
3125 !isa<Constant>(TrueVal))
3126 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
3127 unsigned OpToFold = 0;
3128 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
3130 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
3135 Constant *C = GetSelectFoldableConstant(FVI);
3136 std::string Name = FVI->getName(); FVI->setName("");
3137 Instruction *NewSel =
3138 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
3140 InsertNewInstBefore(NewSel, SI);
3141 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
3142 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
3143 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
3144 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
3146 assert(0 && "Unknown instruction!!");
3155 // CallInst simplification
3157 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
3158 // Intrinsics cannot occur in an invoke, so handle them here instead of in
3160 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(&CI)) {
3161 bool Changed = false;
3163 // memmove/cpy/set of zero bytes is a noop.
3164 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
3165 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
3167 // FIXME: Increase alignment here.
3169 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
3170 if (CI->getRawValue() == 1) {
3171 // Replace the instruction with just byte operations. We would
3172 // transform other cases to loads/stores, but we don't know if
3173 // alignment is sufficient.
3177 // If we have a memmove and the source operation is a constant global,
3178 // then the source and dest pointers can't alias, so we can change this
3179 // into a call to memcpy.
3180 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI))
3181 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
3182 if (GVSrc->isConstant()) {
3183 Module *M = CI.getParent()->getParent()->getParent();
3184 Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
3185 CI.getCalledFunction()->getFunctionType());
3186 CI.setOperand(0, MemCpy);
3190 if (Changed) return &CI;
3193 return visitCallSite(&CI);
3196 // InvokeInst simplification
3198 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
3199 return visitCallSite(&II);
3202 // visitCallSite - Improvements for call and invoke instructions.
3204 Instruction *InstCombiner::visitCallSite(CallSite CS) {
3205 bool Changed = false;
3207 // If the callee is a constexpr cast of a function, attempt to move the cast
3208 // to the arguments of the call/invoke.
3209 if (transformConstExprCastCall(CS)) return 0;
3211 Value *Callee = CS.getCalledValue();
3213 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee))
3214 // This instruction is not reachable, just remove it. Eventually, this
3215 // should get turned into an unreachable instruction.
3216 if (!isa<InvokeInst>(CS.getInstruction())) { // Don't hack the CFG!
3217 if (!CS.getInstruction()->use_empty())
3218 CS.getInstruction()->
3219 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
3220 return EraseInstFromFunction(*CS.getInstruction());
3223 const PointerType *PTy = cast<PointerType>(Callee->getType());
3224 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
3225 if (FTy->isVarArg()) {
3226 // See if we can optimize any arguments passed through the varargs area of
3228 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
3229 E = CS.arg_end(); I != E; ++I)
3230 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
3231 // If this cast does not effect the value passed through the varargs
3232 // area, we can eliminate the use of the cast.
3233 Value *Op = CI->getOperand(0);
3234 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
3241 return Changed ? CS.getInstruction() : 0;
3244 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
3245 // attempt to move the cast to the arguments of the call/invoke.
3247 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
3248 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
3249 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
3250 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
3252 Function *Callee = cast<Function>(CE->getOperand(0));
3253 Instruction *Caller = CS.getInstruction();
3255 // Okay, this is a cast from a function to a different type. Unless doing so
3256 // would cause a type conversion of one of our arguments, change this call to
3257 // be a direct call with arguments casted to the appropriate types.
3259 const FunctionType *FT = Callee->getFunctionType();
3260 const Type *OldRetTy = Caller->getType();
3262 // Check to see if we are changing the return type...
3263 if (OldRetTy != FT->getReturnType()) {
3264 if (Callee->isExternal() &&
3265 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
3266 !Caller->use_empty())
3267 return false; // Cannot transform this return value...
3269 // If the callsite is an invoke instruction, and the return value is used by
3270 // a PHI node in a successor, we cannot change the return type of the call
3271 // because there is no place to put the cast instruction (without breaking
3272 // the critical edge). Bail out in this case.
3273 if (!Caller->use_empty())
3274 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
3275 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
3277 if (PHINode *PN = dyn_cast<PHINode>(*UI))
3278 if (PN->getParent() == II->getNormalDest() ||
3279 PN->getParent() == II->getUnwindDest())
3283 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
3284 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
3286 CallSite::arg_iterator AI = CS.arg_begin();
3287 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
3288 const Type *ParamTy = FT->getParamType(i);
3289 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
3290 if (Callee->isExternal() && !isConvertible) return false;
3293 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
3294 Callee->isExternal())
3295 return false; // Do not delete arguments unless we have a function body...
3297 // Okay, we decided that this is a safe thing to do: go ahead and start
3298 // inserting cast instructions as necessary...
3299 std::vector<Value*> Args;
3300 Args.reserve(NumActualArgs);
3302 AI = CS.arg_begin();
3303 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
3304 const Type *ParamTy = FT->getParamType(i);
3305 if ((*AI)->getType() == ParamTy) {
3306 Args.push_back(*AI);
3308 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
3313 // If the function takes more arguments than the call was taking, add them
3315 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
3316 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
3318 // If we are removing arguments to the function, emit an obnoxious warning...
3319 if (FT->getNumParams() < NumActualArgs)
3320 if (!FT->isVarArg()) {
3321 std::cerr << "WARNING: While resolving call to function '"
3322 << Callee->getName() << "' arguments were dropped!\n";
3324 // Add all of the arguments in their promoted form to the arg list...
3325 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
3326 const Type *PTy = getPromotedType((*AI)->getType());
3327 if (PTy != (*AI)->getType()) {
3328 // Must promote to pass through va_arg area!
3329 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
3330 InsertNewInstBefore(Cast, *Caller);
3331 Args.push_back(Cast);
3333 Args.push_back(*AI);
3338 if (FT->getReturnType() == Type::VoidTy)
3339 Caller->setName(""); // Void type should not have a name...
3342 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
3343 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
3344 Args, Caller->getName(), Caller);
3346 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
3349 // Insert a cast of the return type as necessary...
3351 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
3352 if (NV->getType() != Type::VoidTy) {
3353 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
3355 // If this is an invoke instruction, we should insert it after the first
3356 // non-phi, instruction in the normal successor block.
3357 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
3358 BasicBlock::iterator I = II->getNormalDest()->begin();
3359 while (isa<PHINode>(I)) ++I;
3360 InsertNewInstBefore(NC, *I);
3362 // Otherwise, it's a call, just insert cast right after the call instr
3363 InsertNewInstBefore(NC, *Caller);
3365 AddUsersToWorkList(*Caller);
3367 NV = Constant::getNullValue(Caller->getType());
3371 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
3372 Caller->replaceAllUsesWith(NV);
3373 Caller->getParent()->getInstList().erase(Caller);
3374 removeFromWorkList(Caller);
3380 // PHINode simplification
3382 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
3383 // FIXME: hasConstantValue should ignore undef values!
3384 if (Value *V = hasConstantValue(&PN))
3385 return ReplaceInstUsesWith(PN, V);
3387 // If the only user of this instruction is a cast instruction, and all of the
3388 // incoming values are constants, change this PHI to merge together the casted
3391 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
3392 if (CI->getType() != PN.getType()) { // noop casts will be folded
3393 bool AllConstant = true;
3394 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
3395 if (!isa<Constant>(PN.getIncomingValue(i))) {
3396 AllConstant = false;
3400 // Make a new PHI with all casted values.
3401 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
3402 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
3403 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
3404 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
3405 PN.getIncomingBlock(i));
3408 // Update the cast instruction.
3409 CI->setOperand(0, New);
3410 WorkList.push_back(CI); // revisit the cast instruction to fold.
3411 WorkList.push_back(New); // Make sure to revisit the new Phi
3412 return &PN; // PN is now dead!
3418 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
3419 Instruction *InsertPoint,
3421 unsigned PS = IC->getTargetData().getPointerSize();
3422 const Type *VTy = V->getType();
3424 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
3425 // We must insert a cast to ensure we sign-extend.
3426 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
3427 V->getName()), *InsertPoint);
3428 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
3433 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
3434 Value *PtrOp = GEP.getOperand(0);
3435 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
3436 // If so, eliminate the noop.
3437 if (GEP.getNumOperands() == 1)
3438 return ReplaceInstUsesWith(GEP, PtrOp);
3440 if (isa<UndefValue>(GEP.getOperand(0)))
3441 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
3443 bool HasZeroPointerIndex = false;
3444 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
3445 HasZeroPointerIndex = C->isNullValue();
3447 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
3448 return ReplaceInstUsesWith(GEP, PtrOp);
3450 // Eliminate unneeded casts for indices.
3451 bool MadeChange = false;
3452 gep_type_iterator GTI = gep_type_begin(GEP);
3453 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
3454 if (isa<SequentialType>(*GTI)) {
3455 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
3456 Value *Src = CI->getOperand(0);
3457 const Type *SrcTy = Src->getType();
3458 const Type *DestTy = CI->getType();
3459 if (Src->getType()->isInteger()) {
3460 if (SrcTy->getPrimitiveSize() == DestTy->getPrimitiveSize()) {
3461 // We can always eliminate a cast from ulong or long to the other.
3462 // We can always eliminate a cast from uint to int or the other on
3463 // 32-bit pointer platforms.
3464 if (DestTy->getPrimitiveSize() >= TD->getPointerSize()) {
3466 GEP.setOperand(i, Src);
3468 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
3469 SrcTy->getPrimitiveSize() == 4) {
3470 // We can always eliminate a cast from int to [u]long. We can
3471 // eliminate a cast from uint to [u]long iff the target is a 32-bit
3473 if (SrcTy->isSigned() ||
3474 SrcTy->getPrimitiveSize() >= TD->getPointerSize()) {
3476 GEP.setOperand(i, Src);
3481 // If we are using a wider index than needed for this platform, shrink it
3482 // to what we need. If the incoming value needs a cast instruction,
3483 // insert it. This explicit cast can make subsequent optimizations more
3485 Value *Op = GEP.getOperand(i);
3486 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
3487 if (Constant *C = dyn_cast<Constant>(Op)) {
3488 GEP.setOperand(i, ConstantExpr::getCast(C,
3489 TD->getIntPtrType()->getSignedVersion()));
3492 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
3493 Op->getName()), GEP);
3494 GEP.setOperand(i, Op);
3498 // If this is a constant idx, make sure to canonicalize it to be a signed
3499 // operand, otherwise CSE and other optimizations are pessimized.
3500 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
3501 GEP.setOperand(i, ConstantExpr::getCast(CUI,
3502 CUI->getType()->getSignedVersion()));
3506 if (MadeChange) return &GEP;
3508 // Combine Indices - If the source pointer to this getelementptr instruction
3509 // is a getelementptr instruction, combine the indices of the two
3510 // getelementptr instructions into a single instruction.
3512 std::vector<Value*> SrcGEPOperands;
3513 if (GetElementPtrInst *Src = dyn_cast<GetElementPtrInst>(PtrOp)) {
3514 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
3515 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(PtrOp)) {
3516 if (CE->getOpcode() == Instruction::GetElementPtr)
3517 SrcGEPOperands.assign(CE->op_begin(), CE->op_end());
3520 if (!SrcGEPOperands.empty()) {
3521 // Note that if our source is a gep chain itself that we wait for that
3522 // chain to be resolved before we perform this transformation. This
3523 // avoids us creating a TON of code in some cases.
3525 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
3526 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
3527 return 0; // Wait until our source is folded to completion.
3529 std::vector<Value *> Indices;
3531 // Find out whether the last index in the source GEP is a sequential idx.
3532 bool EndsWithSequential = false;
3533 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
3534 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
3535 EndsWithSequential = !isa<StructType>(*I);
3537 // Can we combine the two pointer arithmetics offsets?
3538 if (EndsWithSequential) {
3539 // Replace: gep (gep %P, long B), long A, ...
3540 // With: T = long A+B; gep %P, T, ...
3542 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
3543 if (SO1 == Constant::getNullValue(SO1->getType())) {
3545 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
3548 // If they aren't the same type, convert both to an integer of the
3549 // target's pointer size.
3550 if (SO1->getType() != GO1->getType()) {
3551 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
3552 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
3553 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
3554 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
3556 unsigned PS = TD->getPointerSize();
3558 if (SO1->getType()->getPrimitiveSize() == PS) {
3559 // Convert GO1 to SO1's type.
3560 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
3562 } else if (GO1->getType()->getPrimitiveSize() == PS) {
3563 // Convert SO1 to GO1's type.
3564 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
3566 const Type *PT = TD->getIntPtrType();
3567 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
3568 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
3572 if (isa<Constant>(SO1) && isa<Constant>(GO1))
3573 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
3575 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
3576 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
3580 // Recycle the GEP we already have if possible.
3581 if (SrcGEPOperands.size() == 2) {
3582 GEP.setOperand(0, SrcGEPOperands[0]);
3583 GEP.setOperand(1, Sum);
3586 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
3587 SrcGEPOperands.end()-1);
3588 Indices.push_back(Sum);
3589 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
3591 } else if (isa<Constant>(*GEP.idx_begin()) &&
3592 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
3593 SrcGEPOperands.size() != 1) {
3594 // Otherwise we can do the fold if the first index of the GEP is a zero
3595 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
3596 SrcGEPOperands.end());
3597 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
3600 if (!Indices.empty())
3601 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
3603 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
3604 // GEP of global variable. If all of the indices for this GEP are
3605 // constants, we can promote this to a constexpr instead of an instruction.
3607 // Scan for nonconstants...
3608 std::vector<Constant*> Indices;
3609 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
3610 for (; I != E && isa<Constant>(*I); ++I)
3611 Indices.push_back(cast<Constant>(*I));
3613 if (I == E) { // If they are all constants...
3614 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
3616 // Replace all uses of the GEP with the new constexpr...
3617 return ReplaceInstUsesWith(GEP, CE);
3619 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(PtrOp)) {
3620 if (CE->getOpcode() == Instruction::Cast) {
3621 if (HasZeroPointerIndex) {
3622 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
3623 // into : GEP [10 x ubyte]* X, long 0, ...
3625 // This occurs when the program declares an array extern like "int X[];"
3627 Constant *X = CE->getOperand(0);
3628 const PointerType *CPTy = cast<PointerType>(CE->getType());
3629 if (const PointerType *XTy = dyn_cast<PointerType>(X->getType()))
3630 if (const ArrayType *XATy =
3631 dyn_cast<ArrayType>(XTy->getElementType()))
3632 if (const ArrayType *CATy =
3633 dyn_cast<ArrayType>(CPTy->getElementType()))
3634 if (CATy->getElementType() == XATy->getElementType()) {
3635 // At this point, we know that the cast source type is a pointer
3636 // to an array of the same type as the destination pointer
3637 // array. Because the array type is never stepped over (there
3638 // is a leading zero) we can fold the cast into this GEP.
3639 GEP.setOperand(0, X);
3649 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
3650 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
3651 if (AI.isArrayAllocation()) // Check C != 1
3652 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
3653 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
3654 AllocationInst *New = 0;
3656 // Create and insert the replacement instruction...
3657 if (isa<MallocInst>(AI))
3658 New = new MallocInst(NewTy, 0, AI.getName());
3660 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
3661 New = new AllocaInst(NewTy, 0, AI.getName());
3664 InsertNewInstBefore(New, AI);
3666 // Scan to the end of the allocation instructions, to skip over a block of
3667 // allocas if possible...
3669 BasicBlock::iterator It = New;
3670 while (isa<AllocationInst>(*It)) ++It;
3672 // Now that I is pointing to the first non-allocation-inst in the block,
3673 // insert our getelementptr instruction...
3675 std::vector<Value*> Idx(2, Constant::getNullValue(Type::IntTy));
3676 Value *V = new GetElementPtrInst(New, Idx, New->getName()+".sub", It);
3678 // Now make everything use the getelementptr instead of the original
3680 return ReplaceInstUsesWith(AI, V);
3681 } else if (isa<UndefValue>(AI.getArraySize())) {
3682 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
3685 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
3686 // Note that we only do this for alloca's, because malloc should allocate and
3687 // return a unique pointer, even for a zero byte allocation.
3688 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
3689 TD->getTypeSize(AI.getAllocatedType()) == 0)
3690 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
3695 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
3696 Value *Op = FI.getOperand(0);
3698 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
3699 if (CastInst *CI = dyn_cast<CastInst>(Op))
3700 if (isa<PointerType>(CI->getOperand(0)->getType())) {
3701 FI.setOperand(0, CI->getOperand(0));
3705 // If we have 'free null' delete the instruction. This can happen in stl code
3706 // when lots of inlining happens.
3707 // FIXME: free undef should be xformed into an 'unreachable' instruction.
3708 if (isa<ConstantPointerNull>(Op) || isa<UndefValue>(Op))
3709 return EraseInstFromFunction(FI);
3715 /// GetGEPGlobalInitializer - Given a constant, and a getelementptr
3716 /// constantexpr, return the constant value being addressed by the constant
3717 /// expression, or null if something is funny.
3719 static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
3720 if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
3721 return 0; // Do not allow stepping over the value!
3723 // Loop over all of the operands, tracking down which value we are
3725 gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
3726 for (++I; I != E; ++I)
3727 if (const StructType *STy = dyn_cast<StructType>(*I)) {
3728 ConstantUInt *CU = cast<ConstantUInt>(I.getOperand());
3729 assert(CU->getValue() < STy->getNumElements() &&
3730 "Struct index out of range!");
3731 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
3732 C = CS->getOperand(CU->getValue());
3733 } else if (isa<ConstantAggregateZero>(C)) {
3734 C = Constant::getNullValue(STy->getElementType(CU->getValue()));
3735 } else if (isa<UndefValue>(C)) {
3736 C = UndefValue::get(STy->getElementType(CU->getValue()));
3740 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
3741 const ArrayType *ATy = cast<ArrayType>(*I);
3742 if ((uint64_t)CI->getRawValue() >= ATy->getNumElements()) return 0;
3743 if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
3744 C = CA->getOperand(CI->getRawValue());
3745 else if (isa<ConstantAggregateZero>(C))
3746 C = Constant::getNullValue(ATy->getElementType());
3747 else if (isa<UndefValue>(C))
3748 C = UndefValue::get(ATy->getElementType());
3757 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
3758 User *CI = cast<User>(LI.getOperand(0));
3760 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
3761 if (const PointerType *SrcTy =
3762 dyn_cast<PointerType>(CI->getOperand(0)->getType())) {
3763 const Type *SrcPTy = SrcTy->getElementType();
3764 if (SrcPTy->isSized() && DestPTy->isSized() &&
3765 IC.getTargetData().getTypeSize(SrcPTy) ==
3766 IC.getTargetData().getTypeSize(DestPTy) &&
3767 (SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
3768 (DestPTy->isInteger() || isa<PointerType>(DestPTy))) {
3769 // Okay, we are casting from one integer or pointer type to another of
3770 // the same size. Instead of casting the pointer before the load, cast
3771 // the result of the loaded value.
3772 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CI->getOperand(0),
3774 LI.isVolatile()),LI);
3775 // Now cast the result of the load.
3776 return new CastInst(NewLoad, LI.getType());
3782 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
3783 /// from this value cannot trap. If it is not obviously safe to load from the
3784 /// specified pointer, we do a quick local scan of the basic block containing
3785 /// ScanFrom, to determine if the address is already accessed.
3786 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
3787 // If it is an alloca or global variable, it is always safe to load from.
3788 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
3790 // Otherwise, be a little bit agressive by scanning the local block where we
3791 // want to check to see if the pointer is already being loaded or stored
3792 // from/to. If so, the previous load or store would have already trapped,
3793 // so there is no harm doing an extra load (also, CSE will later eliminate
3794 // the load entirely).
3795 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
3800 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
3801 if (LI->getOperand(0) == V) return true;
3802 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
3803 if (SI->getOperand(1) == V) return true;
3809 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
3810 Value *Op = LI.getOperand(0);
3812 if (Constant *C = dyn_cast<Constant>(Op)) {
3813 if ((C->isNullValue() || isa<UndefValue>(C)) &&
3814 !LI.isVolatile()) // load null -> undef
3815 // FIXME: this should become an unreachable instruction
3816 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
3818 // Instcombine load (constant global) into the value loaded.
3819 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
3820 if (GV->isConstant() && !GV->isExternal())
3821 return ReplaceInstUsesWith(LI, GV->getInitializer());
3823 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
3824 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
3825 if (CE->getOpcode() == Instruction::GetElementPtr) {
3826 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
3827 if (GV->isConstant() && !GV->isExternal())
3828 if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
3829 return ReplaceInstUsesWith(LI, V);
3830 } else if (CE->getOpcode() == Instruction::Cast) {
3831 if (Instruction *Res = InstCombineLoadCast(*this, LI))
3836 // load (cast X) --> cast (load X) iff safe
3837 if (CastInst *CI = dyn_cast<CastInst>(Op))
3838 if (Instruction *Res = InstCombineLoadCast(*this, LI))
3841 if (!LI.isVolatile() && Op->hasOneUse()) {
3842 // Change select and PHI nodes to select values instead of addresses: this
3843 // helps alias analysis out a lot, allows many others simplifications, and
3844 // exposes redundancy in the code.
3846 // Note that we cannot do the transformation unless we know that the
3847 // introduced loads cannot trap! Something like this is valid as long as
3848 // the condition is always false: load (select bool %C, int* null, int* %G),
3849 // but it would not be valid if we transformed it to load from null
3852 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
3853 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
3854 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
3855 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
3856 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
3857 SI->getOperand(1)->getName()+".val"), LI);
3858 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
3859 SI->getOperand(2)->getName()+".val"), LI);
3860 return new SelectInst(SI->getCondition(), V1, V2);
3863 // load (select (cond, null, P)) -> load P
3864 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
3865 if (C->isNullValue()) {
3866 LI.setOperand(0, SI->getOperand(2));
3870 // load (select (cond, P, null)) -> load P
3871 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
3872 if (C->isNullValue()) {
3873 LI.setOperand(0, SI->getOperand(1));
3877 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
3878 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
3879 bool Safe = PN->getParent() == LI.getParent();
3881 // Scan all of the instructions between the PHI and the load to make
3882 // sure there are no instructions that might possibly alter the value
3883 // loaded from the PHI.
3885 BasicBlock::iterator I = &LI;
3886 for (--I; !isa<PHINode>(I); --I)
3887 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
3893 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
3894 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
3895 PN->getIncomingBlock(i)->getTerminator()))
3900 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
3901 InsertNewInstBefore(NewPN, *PN);
3902 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
3904 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
3905 BasicBlock *BB = PN->getIncomingBlock(i);
3906 Value *&TheLoad = LoadMap[BB];
3908 Value *InVal = PN->getIncomingValue(i);
3909 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
3910 InVal->getName()+".val"),
3911 *BB->getTerminator());
3913 NewPN->addIncoming(TheLoad, BB);
3915 return ReplaceInstUsesWith(LI, NewPN);
3922 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
3923 if (isa<ConstantPointerNull>(SI.getOperand(1)) ||
3924 isa<UndefValue>(SI.getOperand(1))) {
3925 // FIXME: This should become an unreachable instruction.
3926 return EraseInstFromFunction(SI);
3934 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
3935 // Change br (not X), label True, label False to: br X, label False, True
3937 BasicBlock *TrueDest;
3938 BasicBlock *FalseDest;
3939 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
3940 !isa<Constant>(X)) {
3941 // Swap Destinations and condition...
3943 BI.setSuccessor(0, FalseDest);
3944 BI.setSuccessor(1, TrueDest);
3948 // Cannonicalize setne -> seteq
3949 Instruction::BinaryOps Op; Value *Y;
3950 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
3951 TrueDest, FalseDest)))
3952 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
3953 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
3954 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
3955 std::string Name = I->getName(); I->setName("");
3956 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
3957 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
3958 // Swap Destinations and condition...
3959 BI.setCondition(NewSCC);
3960 BI.setSuccessor(0, FalseDest);
3961 BI.setSuccessor(1, TrueDest);
3962 removeFromWorkList(I);
3963 I->getParent()->getInstList().erase(I);
3964 WorkList.push_back(cast<Instruction>(NewSCC));
3971 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
3972 Value *Cond = SI.getCondition();
3973 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
3974 if (I->getOpcode() == Instruction::Add)
3975 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
3976 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
3977 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
3978 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
3980 SI.setOperand(0, I->getOperand(0));
3981 WorkList.push_back(I);
3989 void InstCombiner::removeFromWorkList(Instruction *I) {
3990 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
3994 bool InstCombiner::runOnFunction(Function &F) {
3995 bool Changed = false;
3996 TD = &getAnalysis<TargetData>();
3998 for (inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i)
3999 WorkList.push_back(&*i);
4002 while (!WorkList.empty()) {
4003 Instruction *I = WorkList.back(); // Get an instruction from the worklist
4004 WorkList.pop_back();
4006 // Check to see if we can DCE or ConstantPropagate the instruction...
4007 // Check to see if we can DIE the instruction...
4008 if (isInstructionTriviallyDead(I)) {
4009 // Add operands to the worklist...
4010 if (I->getNumOperands() < 4)
4011 AddUsesToWorkList(*I);
4014 I->getParent()->getInstList().erase(I);
4015 removeFromWorkList(I);
4019 // Instruction isn't dead, see if we can constant propagate it...
4020 if (Constant *C = ConstantFoldInstruction(I)) {
4021 // Add operands to the worklist...
4022 AddUsesToWorkList(*I);
4023 ReplaceInstUsesWith(*I, C);
4026 I->getParent()->getInstList().erase(I);
4027 removeFromWorkList(I);
4031 // Now that we have an instruction, try combining it to simplify it...
4032 if (Instruction *Result = visit(*I)) {
4034 // Should we replace the old instruction with a new one?
4036 DEBUG(std::cerr << "IC: Old = " << *I
4037 << " New = " << *Result);
4039 // Everything uses the new instruction now.
4040 I->replaceAllUsesWith(Result);
4042 // Push the new instruction and any users onto the worklist.
4043 WorkList.push_back(Result);
4044 AddUsersToWorkList(*Result);
4046 // Move the name to the new instruction first...
4047 std::string OldName = I->getName(); I->setName("");
4048 Result->setName(OldName);
4050 // Insert the new instruction into the basic block...
4051 BasicBlock *InstParent = I->getParent();
4052 InstParent->getInstList().insert(I, Result);
4054 // Make sure that we reprocess all operands now that we reduced their
4056 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
4057 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
4058 WorkList.push_back(OpI);
4060 // Instructions can end up on the worklist more than once. Make sure
4061 // we do not process an instruction that has been deleted.
4062 removeFromWorkList(I);
4064 // Erase the old instruction.
4065 InstParent->getInstList().erase(I);
4067 DEBUG(std::cerr << "IC: MOD = " << *I);
4069 // If the instruction was modified, it's possible that it is now dead.
4070 // if so, remove it.
4071 if (isInstructionTriviallyDead(I)) {
4072 // Make sure we process all operands now that we are reducing their
4074 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
4075 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
4076 WorkList.push_back(OpI);
4078 // Instructions may end up in the worklist more than once. Erase all
4079 // occurrances of this instruction.
4080 removeFromWorkList(I);
4081 I->getParent()->getInstList().erase(I);
4083 WorkList.push_back(Result);
4084 AddUsersToWorkList(*Result);
4094 FunctionPass *llvm::createInstructionCombiningPass() {
4095 return new InstCombiner();