1 //===- InstructionCombining.cpp - Combine multiple instructions -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // InstructionCombining - Combine instructions to form fewer, simple
11 // instructions. This pass does not modify the CFG This pass is where algebraic
12 // simplification happens.
14 // This pass combines things like:
20 // This is a simple worklist driven algorithm.
22 // This pass guarantees that the following canonicalizations are performed on
24 // 1. If a binary operator has a constant operand, it is moved to the RHS
25 // 2. Bitwise operators with constant operands are always grouped so that
26 // shifts are performed first, then or's, then and's, then xor's.
27 // 3. SetCC instructions are converted from <,>,<=,>= to ==,!= if possible
28 // 4. All SetCC instructions on boolean values are replaced with logical ops
29 // 5. add X, X is represented as (X*2) => (X << 1)
30 // 6. Multiplies with a power-of-two constant argument are transformed into
34 //===----------------------------------------------------------------------===//
36 #define DEBUG_TYPE "instcombine"
37 #include "llvm/Transforms/Scalar.h"
38 #include "llvm/IntrinsicInst.h"
39 #include "llvm/Pass.h"
40 #include "llvm/DerivedTypes.h"
41 #include "llvm/GlobalVariable.h"
42 #include "llvm/Target/TargetData.h"
43 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
44 #include "llvm/Transforms/Utils/Local.h"
45 #include "llvm/Support/CallSite.h"
46 #include "llvm/Support/Debug.h"
47 #include "llvm/Support/GetElementPtrTypeIterator.h"
48 #include "llvm/Support/InstVisitor.h"
49 #include "llvm/Support/MathExtras.h"
50 #include "llvm/Support/PatternMatch.h"
51 #include "llvm/ADT/DepthFirstIterator.h"
52 #include "llvm/ADT/Statistic.h"
53 #include "llvm/ADT/STLExtras.h"
56 using namespace llvm::PatternMatch;
59 Statistic<> NumCombined ("instcombine", "Number of insts combined");
60 Statistic<> NumConstProp("instcombine", "Number of constant folds");
61 Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
62 Statistic<> NumSunkInst ("instcombine", "Number of instructions sunk");
64 class InstCombiner : public FunctionPass,
65 public InstVisitor<InstCombiner, Instruction*> {
66 // Worklist of all of the instructions that need to be simplified.
67 std::vector<Instruction*> WorkList;
70 /// AddUsersToWorkList - When an instruction is simplified, add all users of
71 /// the instruction to the work lists because they might get more simplified
74 void AddUsersToWorkList(Instruction &I) {
75 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
77 WorkList.push_back(cast<Instruction>(*UI));
80 /// AddUsesToWorkList - When an instruction is simplified, add operands to
81 /// the work lists because they might get more simplified now.
83 void AddUsesToWorkList(Instruction &I) {
84 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
85 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
86 WorkList.push_back(Op);
89 // removeFromWorkList - remove all instances of I from the worklist.
90 void removeFromWorkList(Instruction *I);
92 virtual bool runOnFunction(Function &F);
94 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
95 AU.addRequired<TargetData>();
99 TargetData &getTargetData() const { return *TD; }
101 // Visitation implementation - Implement instruction combining for different
102 // instruction types. The semantics are as follows:
104 // null - No change was made
105 // I - Change was made, I is still valid, I may be dead though
106 // otherwise - Change was made, replace I with returned instruction
108 Instruction *visitAdd(BinaryOperator &I);
109 Instruction *visitSub(BinaryOperator &I);
110 Instruction *visitMul(BinaryOperator &I);
111 Instruction *visitDiv(BinaryOperator &I);
112 Instruction *visitRem(BinaryOperator &I);
113 Instruction *visitAnd(BinaryOperator &I);
114 Instruction *visitOr (BinaryOperator &I);
115 Instruction *visitXor(BinaryOperator &I);
116 Instruction *visitSetCondInst(SetCondInst &I);
117 Instruction *visitSetCondInstWithCastAndCast(SetCondInst &SCI);
119 Instruction *FoldGEPSetCC(User *GEPLHS, Value *RHS,
120 Instruction::BinaryOps Cond, Instruction &I);
121 Instruction *visitShiftInst(ShiftInst &I);
122 Instruction *visitCastInst(CastInst &CI);
123 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
125 Instruction *visitSelectInst(SelectInst &CI);
126 Instruction *visitCallInst(CallInst &CI);
127 Instruction *visitInvokeInst(InvokeInst &II);
128 Instruction *visitPHINode(PHINode &PN);
129 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
130 Instruction *visitAllocationInst(AllocationInst &AI);
131 Instruction *visitFreeInst(FreeInst &FI);
132 Instruction *visitLoadInst(LoadInst &LI);
133 Instruction *visitStoreInst(StoreInst &SI);
134 Instruction *visitBranchInst(BranchInst &BI);
135 Instruction *visitSwitchInst(SwitchInst &SI);
137 // visitInstruction - Specify what to return for unhandled instructions...
138 Instruction *visitInstruction(Instruction &I) { return 0; }
141 Instruction *visitCallSite(CallSite CS);
142 bool transformConstExprCastCall(CallSite CS);
145 // InsertNewInstBefore - insert an instruction New before instruction Old
146 // in the program. Add the new instruction to the worklist.
148 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
149 assert(New && New->getParent() == 0 &&
150 "New instruction already inserted into a basic block!");
151 BasicBlock *BB = Old.getParent();
152 BB->getInstList().insert(&Old, New); // Insert inst
153 WorkList.push_back(New); // Add to worklist
157 /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
158 /// This also adds the cast to the worklist. Finally, this returns the
160 Value *InsertCastBefore(Value *V, const Type *Ty, Instruction &Pos) {
161 if (V->getType() == Ty) return V;
163 Instruction *C = new CastInst(V, Ty, V->getName(), &Pos);
164 WorkList.push_back(C);
168 // ReplaceInstUsesWith - This method is to be used when an instruction is
169 // found to be dead, replacable with another preexisting expression. Here
170 // we add all uses of I to the worklist, replace all uses of I with the new
171 // value, then return I, so that the inst combiner will know that I was
174 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
175 AddUsersToWorkList(I); // Add all modified instrs to worklist
177 I.replaceAllUsesWith(V);
180 // If we are replacing the instruction with itself, this must be in a
181 // segment of unreachable code, so just clobber the instruction.
182 I.replaceAllUsesWith(UndefValue::get(I.getType()));
187 // EraseInstFromFunction - When dealing with an instruction that has side
188 // effects or produces a void value, we can't rely on DCE to delete the
189 // instruction. Instead, visit methods should return the value returned by
191 Instruction *EraseInstFromFunction(Instruction &I) {
192 assert(I.use_empty() && "Cannot erase instruction that is used!");
193 AddUsesToWorkList(I);
194 removeFromWorkList(&I);
196 return 0; // Don't do anything with FI
201 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
202 /// InsertBefore instruction. This is specialized a bit to avoid inserting
203 /// casts that are known to not do anything...
205 Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
206 Instruction *InsertBefore);
208 // SimplifyCommutative - This performs a few simplifications for commutative
210 bool SimplifyCommutative(BinaryOperator &I);
213 // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
214 // PHI node as operand #0, see if we can fold the instruction into the PHI
215 // (which is only possible if all operands to the PHI are constants).
216 Instruction *FoldOpIntoPhi(Instruction &I);
218 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
219 // operator and they all are only used by the PHI, PHI together their
220 // inputs, and do the operation once, to the result of the PHI.
221 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
223 Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
224 ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
226 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantIntegral *Mask,
227 bool isSub, Instruction &I);
228 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
229 bool Inside, Instruction &IB);
230 Instruction *PromoteCastOfAllocation(CastInst &CI, AllocationInst &AI);
233 RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
236 // getComplexity: Assign a complexity or rank value to LLVM Values...
237 // 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
238 static unsigned getComplexity(Value *V) {
239 if (isa<Instruction>(V)) {
240 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
244 if (isa<Argument>(V)) return 3;
245 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
248 // isOnlyUse - Return true if this instruction will be deleted if we stop using
250 static bool isOnlyUse(Value *V) {
251 return V->hasOneUse() || isa<Constant>(V);
254 // getPromotedType - Return the specified type promoted as it would be to pass
255 // though a va_arg area...
256 static const Type *getPromotedType(const Type *Ty) {
257 switch (Ty->getTypeID()) {
258 case Type::SByteTyID:
259 case Type::ShortTyID: return Type::IntTy;
260 case Type::UByteTyID:
261 case Type::UShortTyID: return Type::UIntTy;
262 case Type::FloatTyID: return Type::DoubleTy;
267 /// isCast - If the specified operand is a CastInst or a constant expr cast,
268 /// return the operand value, otherwise return null.
269 static Value *isCast(Value *V) {
270 if (CastInst *I = dyn_cast<CastInst>(V))
271 return I->getOperand(0);
272 else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
273 if (CE->getOpcode() == Instruction::Cast)
274 return CE->getOperand(0);
278 // SimplifyCommutative - This performs a few simplifications for commutative
281 // 1. Order operands such that they are listed from right (least complex) to
282 // left (most complex). This puts constants before unary operators before
285 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
286 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
288 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
289 bool Changed = false;
290 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
291 Changed = !I.swapOperands();
293 if (!I.isAssociative()) return Changed;
294 Instruction::BinaryOps Opcode = I.getOpcode();
295 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
296 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
297 if (isa<Constant>(I.getOperand(1))) {
298 Constant *Folded = ConstantExpr::get(I.getOpcode(),
299 cast<Constant>(I.getOperand(1)),
300 cast<Constant>(Op->getOperand(1)));
301 I.setOperand(0, Op->getOperand(0));
302 I.setOperand(1, Folded);
304 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
305 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
306 isOnlyUse(Op) && isOnlyUse(Op1)) {
307 Constant *C1 = cast<Constant>(Op->getOperand(1));
308 Constant *C2 = cast<Constant>(Op1->getOperand(1));
310 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
311 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
312 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
315 WorkList.push_back(New);
316 I.setOperand(0, New);
317 I.setOperand(1, Folded);
324 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
325 // if the LHS is a constant zero (which is the 'negate' form).
327 static inline Value *dyn_castNegVal(Value *V) {
328 if (BinaryOperator::isNeg(V))
329 return BinaryOperator::getNegArgument(V);
331 // Constants can be considered to be negated values if they can be folded.
332 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
333 return ConstantExpr::getNeg(C);
337 static inline Value *dyn_castNotVal(Value *V) {
338 if (BinaryOperator::isNot(V))
339 return BinaryOperator::getNotArgument(V);
341 // Constants can be considered to be not'ed values...
342 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
343 return ConstantExpr::getNot(C);
347 // dyn_castFoldableMul - If this value is a multiply that can be folded into
348 // other computations (because it has a constant operand), return the
349 // non-constant operand of the multiply, and set CST to point to the multiplier.
350 // Otherwise, return null.
352 static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
353 if (V->hasOneUse() && V->getType()->isInteger())
354 if (Instruction *I = dyn_cast<Instruction>(V)) {
355 if (I->getOpcode() == Instruction::Mul)
356 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
357 return I->getOperand(0);
358 if (I->getOpcode() == Instruction::Shl)
359 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
360 // The multiplier is really 1 << CST.
361 Constant *One = ConstantInt::get(V->getType(), 1);
362 CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
363 return I->getOperand(0);
369 /// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
370 /// expression, return it.
371 static User *dyn_castGetElementPtr(Value *V) {
372 if (isa<GetElementPtrInst>(V)) return cast<User>(V);
373 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
374 if (CE->getOpcode() == Instruction::GetElementPtr)
375 return cast<User>(V);
379 // AddOne, SubOne - Add or subtract a constant one from an integer constant...
380 static ConstantInt *AddOne(ConstantInt *C) {
381 return cast<ConstantInt>(ConstantExpr::getAdd(C,
382 ConstantInt::get(C->getType(), 1)));
384 static ConstantInt *SubOne(ConstantInt *C) {
385 return cast<ConstantInt>(ConstantExpr::getSub(C,
386 ConstantInt::get(C->getType(), 1)));
389 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
390 /// this predicate to simplify operations downstream. V and Mask are known to
391 /// be the same type.
392 static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask,
393 unsigned Depth = 0) {
394 // Note, we cannot consider 'undef' to be "IsZero" here. The problem is that
395 // we cannot optimize based on the assumption that it is zero without changing
396 // to to an explicit zero. If we don't change it to zero, other code could
397 // optimized based on the contradictory assumption that it is non-zero.
398 // Because instcombine aggressively folds operations with undef args anyway,
399 // this won't lose us code quality.
400 if (Mask->isNullValue())
402 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
403 return ConstantExpr::getAnd(CI, Mask)->isNullValue();
405 if (Depth == 6) return false; // Limit search depth.
407 if (Instruction *I = dyn_cast<Instruction>(V)) {
408 switch (I->getOpcode()) {
409 case Instruction::And:
410 // (X & C1) & C2 == 0 iff C1 & C2 == 0.
411 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1))) {
412 ConstantIntegral *C1C2 =
413 cast<ConstantIntegral>(ConstantExpr::getAnd(CI, Mask));
414 if (MaskedValueIsZero(I->getOperand(0), C1C2, Depth+1))
417 // If either the LHS or the RHS are MaskedValueIsZero, the result is zero.
418 return MaskedValueIsZero(I->getOperand(1), Mask, Depth+1) ||
419 MaskedValueIsZero(I->getOperand(0), Mask, Depth+1);
420 case Instruction::Or:
421 case Instruction::Xor:
422 // If the LHS and the RHS are MaskedValueIsZero, the result is also zero.
423 return MaskedValueIsZero(I->getOperand(1), Mask, Depth+1) &&
424 MaskedValueIsZero(I->getOperand(0), Mask, Depth+1);
425 case Instruction::Select:
426 // If the T and F values are MaskedValueIsZero, the result is also zero.
427 return MaskedValueIsZero(I->getOperand(2), Mask, Depth+1) &&
428 MaskedValueIsZero(I->getOperand(1), Mask, Depth+1);
429 case Instruction::Cast: {
430 const Type *SrcTy = I->getOperand(0)->getType();
431 if (SrcTy == Type::BoolTy)
432 return (Mask->getRawValue() & 1) == 0;
434 if (SrcTy->isInteger()) {
435 // (cast <ty> X to int) & C2 == 0 iff <ty> could not have contained C2.
436 if (SrcTy->isUnsigned() && // Only handle zero ext.
437 ConstantExpr::getCast(Mask, SrcTy)->isNullValue())
440 // If this is a noop cast, recurse.
441 if ((SrcTy->isSigned() && SrcTy->getUnsignedVersion() == I->getType())||
442 SrcTy->getSignedVersion() == I->getType()) {
444 ConstantExpr::getCast(Mask, I->getOperand(0)->getType());
445 return MaskedValueIsZero(I->getOperand(0),
446 cast<ConstantIntegral>(NewMask), Depth+1);
451 case Instruction::Shl:
452 // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
453 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
454 return MaskedValueIsZero(I->getOperand(0),
455 cast<ConstantIntegral>(ConstantExpr::getUShr(Mask, SA)),
458 case Instruction::Shr:
459 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
460 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
461 if (I->getType()->isUnsigned()) {
462 Constant *C1 = ConstantIntegral::getAllOnesValue(I->getType());
463 C1 = ConstantExpr::getShr(C1, SA);
464 C1 = ConstantExpr::getAnd(C1, Mask);
465 if (C1->isNullValue())
475 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
476 // true when both operands are equal...
478 static bool isTrueWhenEqual(Instruction &I) {
479 return I.getOpcode() == Instruction::SetEQ ||
480 I.getOpcode() == Instruction::SetGE ||
481 I.getOpcode() == Instruction::SetLE;
484 /// AssociativeOpt - Perform an optimization on an associative operator. This
485 /// function is designed to check a chain of associative operators for a
486 /// potential to apply a certain optimization. Since the optimization may be
487 /// applicable if the expression was reassociated, this checks the chain, then
488 /// reassociates the expression as necessary to expose the optimization
489 /// opportunity. This makes use of a special Functor, which must define
490 /// 'shouldApply' and 'apply' methods.
492 template<typename Functor>
493 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
494 unsigned Opcode = Root.getOpcode();
495 Value *LHS = Root.getOperand(0);
497 // Quick check, see if the immediate LHS matches...
498 if (F.shouldApply(LHS))
499 return F.apply(Root);
501 // Otherwise, if the LHS is not of the same opcode as the root, return.
502 Instruction *LHSI = dyn_cast<Instruction>(LHS);
503 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
504 // Should we apply this transform to the RHS?
505 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
507 // If not to the RHS, check to see if we should apply to the LHS...
508 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
509 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
513 // If the functor wants to apply the optimization to the RHS of LHSI,
514 // reassociate the expression from ((? op A) op B) to (? op (A op B))
516 BasicBlock *BB = Root.getParent();
518 // Now all of the instructions are in the current basic block, go ahead
519 // and perform the reassociation.
520 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
522 // First move the selected RHS to the LHS of the root...
523 Root.setOperand(0, LHSI->getOperand(1));
525 // Make what used to be the LHS of the root be the user of the root...
526 Value *ExtraOperand = TmpLHSI->getOperand(1);
527 if (&Root == TmpLHSI) {
528 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
531 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
532 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
533 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
534 BasicBlock::iterator ARI = &Root; ++ARI;
535 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
538 // Now propagate the ExtraOperand down the chain of instructions until we
540 while (TmpLHSI != LHSI) {
541 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
542 // Move the instruction to immediately before the chain we are
543 // constructing to avoid breaking dominance properties.
544 NextLHSI->getParent()->getInstList().remove(NextLHSI);
545 BB->getInstList().insert(ARI, NextLHSI);
548 Value *NextOp = NextLHSI->getOperand(1);
549 NextLHSI->setOperand(1, ExtraOperand);
551 ExtraOperand = NextOp;
554 // Now that the instructions are reassociated, have the functor perform
555 // the transformation...
556 return F.apply(Root);
559 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
565 // AddRHS - Implements: X + X --> X << 1
568 AddRHS(Value *rhs) : RHS(rhs) {}
569 bool shouldApply(Value *LHS) const { return LHS == RHS; }
570 Instruction *apply(BinaryOperator &Add) const {
571 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
572 ConstantInt::get(Type::UByteTy, 1));
576 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
578 struct AddMaskingAnd {
580 AddMaskingAnd(Constant *c) : C2(c) {}
581 bool shouldApply(Value *LHS) const {
583 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
584 ConstantExpr::getAnd(C1, C2)->isNullValue();
586 Instruction *apply(BinaryOperator &Add) const {
587 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
591 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
593 if (isa<CastInst>(I)) {
594 if (Constant *SOC = dyn_cast<Constant>(SO))
595 return ConstantExpr::getCast(SOC, I.getType());
597 return IC->InsertNewInstBefore(new CastInst(SO, I.getType(),
598 SO->getName() + ".cast"), I);
601 // Figure out if the constant is the left or the right argument.
602 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
603 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
605 if (Constant *SOC = dyn_cast<Constant>(SO)) {
607 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
608 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
611 Value *Op0 = SO, *Op1 = ConstOperand;
615 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
616 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
617 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&I))
618 New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh");
620 assert(0 && "Unknown binary instruction type!");
623 return IC->InsertNewInstBefore(New, I);
626 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
627 // constant as the other operand, try to fold the binary operator into the
628 // select arguments. This also works for Cast instructions, which obviously do
629 // not have a second operand.
630 static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
632 // Don't modify shared select instructions
633 if (!SI->hasOneUse()) return 0;
634 Value *TV = SI->getOperand(1);
635 Value *FV = SI->getOperand(2);
637 if (isa<Constant>(TV) || isa<Constant>(FV)) {
638 // Bool selects with constant operands can be folded to logical ops.
639 if (SI->getType() == Type::BoolTy) return 0;
641 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
642 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
644 return new SelectInst(SI->getCondition(), SelectTrueVal,
651 /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
652 /// node as operand #0, see if we can fold the instruction into the PHI (which
653 /// is only possible if all operands to the PHI are constants).
654 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
655 PHINode *PN = cast<PHINode>(I.getOperand(0));
656 unsigned NumPHIValues = PN->getNumIncomingValues();
657 if (!PN->hasOneUse() || NumPHIValues == 0 ||
658 !isa<Constant>(PN->getIncomingValue(0))) return 0;
660 // Check to see if all of the operands of the PHI are constants. If not, we
661 // cannot do the transformation.
662 for (unsigned i = 1; i != NumPHIValues; ++i)
663 if (!isa<Constant>(PN->getIncomingValue(i)))
666 // Okay, we can do the transformation: create the new PHI node.
667 PHINode *NewPN = new PHINode(I.getType(), I.getName());
669 NewPN->reserveOperandSpace(PN->getNumOperands()/2);
670 InsertNewInstBefore(NewPN, *PN);
672 // Next, add all of the operands to the PHI.
673 if (I.getNumOperands() == 2) {
674 Constant *C = cast<Constant>(I.getOperand(1));
675 for (unsigned i = 0; i != NumPHIValues; ++i) {
676 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
677 NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
678 PN->getIncomingBlock(i));
681 assert(isa<CastInst>(I) && "Unary op should be a cast!");
682 const Type *RetTy = I.getType();
683 for (unsigned i = 0; i != NumPHIValues; ++i) {
684 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
685 NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
686 PN->getIncomingBlock(i));
689 return ReplaceInstUsesWith(I, NewPN);
692 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
693 bool Changed = SimplifyCommutative(I);
694 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
696 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
697 // X + undef -> undef
698 if (isa<UndefValue>(RHS))
699 return ReplaceInstUsesWith(I, RHS);
702 if (!I.getType()->isFloatingPoint()) { // NOTE: -0 + +0 = +0.
703 if (RHSC->isNullValue())
704 return ReplaceInstUsesWith(I, LHS);
705 } else if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
706 if (CFP->isExactlyValue(-0.0))
707 return ReplaceInstUsesWith(I, LHS);
710 // X + (signbit) --> X ^ signbit
711 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
712 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
713 uint64_t Val = CI->getRawValue() & (~0ULL >> (64- NumBits));
714 if (Val == (1ULL << (NumBits-1)))
715 return BinaryOperator::createXor(LHS, RHS);
718 if (isa<PHINode>(LHS))
719 if (Instruction *NV = FoldOpIntoPhi(I))
724 if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
725 unsigned TySizeBits = I.getType()->getPrimitiveSizeInBits();
726 int64_t RHSSExt = cast<ConstantInt>(RHSC)->getSExtValue();
727 uint64_t RHSZExt = cast<ConstantInt>(RHSC)->getZExtValue();
729 uint64_t C0080Val = 1ULL << 31;
730 int64_t CFF80Val = -C0080Val;
733 if (TySizeBits > Size) {
735 // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
736 // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
737 if (RHSSExt == CFF80Val) {
738 if (XorRHS->getZExtValue() == C0080Val)
740 } else if (RHSZExt == C0080Val) {
741 if (XorRHS->getSExtValue() == CFF80Val)
745 // This is a sign extend if the top bits are known zero.
746 Constant *Mask = ConstantInt::getAllOnesValue(XorLHS->getType());
747 Mask = ConstantExpr::getShl(Mask,
748 ConstantInt::get(Type::UByteTy, 64-TySizeBits-Size));
749 if (!MaskedValueIsZero(XorLHS, cast<ConstantInt>(Mask)))
750 Size = 0; // Not a sign ext, but can't be any others either.
760 const Type *MiddleType = 0;
763 case 32: MiddleType = Type::IntTy; break;
764 case 16: MiddleType = Type::ShortTy; break;
765 case 8: MiddleType = Type::SByteTy; break;
768 Instruction *NewTrunc = new CastInst(XorLHS, MiddleType, "sext");
769 InsertNewInstBefore(NewTrunc, I);
770 return new CastInst(NewTrunc, I.getType());
776 if (I.getType()->isInteger()) {
777 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
779 if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
780 if (RHSI->getOpcode() == Instruction::Sub)
781 if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
782 return ReplaceInstUsesWith(I, RHSI->getOperand(0));
784 if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
785 if (LHSI->getOpcode() == Instruction::Sub)
786 if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
787 return ReplaceInstUsesWith(I, LHSI->getOperand(0));
792 if (Value *V = dyn_castNegVal(LHS))
793 return BinaryOperator::createSub(RHS, V);
796 if (!isa<Constant>(RHS))
797 if (Value *V = dyn_castNegVal(RHS))
798 return BinaryOperator::createSub(LHS, V);
802 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
803 if (X == RHS) // X*C + X --> X * (C+1)
804 return BinaryOperator::createMul(RHS, AddOne(C2));
806 // X*C1 + X*C2 --> X * (C1+C2)
808 if (X == dyn_castFoldableMul(RHS, C1))
809 return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2));
812 // X + X*C --> X * (C+1)
813 if (dyn_castFoldableMul(RHS, C2) == LHS)
814 return BinaryOperator::createMul(LHS, AddOne(C2));
817 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
818 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
819 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
821 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
823 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
824 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
825 return BinaryOperator::createSub(C, X);
828 // (X & FF00) + xx00 -> (X+xx00) & FF00
829 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
830 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
832 // See if all bits from the first bit set in the Add RHS up are included
833 // in the mask. First, get the rightmost bit.
834 uint64_t AddRHSV = CRHS->getRawValue();
836 // Form a mask of all bits from the lowest bit added through the top.
837 uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
838 AddRHSHighBits &= ~0ULL >> (64-C2->getType()->getPrimitiveSizeInBits());
840 // See if the and mask includes all of these bits.
841 uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue();
843 if (AddRHSHighBits == AddRHSHighBitsAnd) {
844 // Okay, the xform is safe. Insert the new add pronto.
845 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
847 return BinaryOperator::createAnd(NewAdd, C2);
852 // Try to fold constant add into select arguments.
853 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
854 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
858 return Changed ? &I : 0;
861 // isSignBit - Return true if the value represented by the constant only has the
862 // highest order bit set.
863 static bool isSignBit(ConstantInt *CI) {
864 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
865 return (CI->getRawValue() & (~0ULL >> (64-NumBits))) == (1ULL << (NumBits-1));
868 /// RemoveNoopCast - Strip off nonconverting casts from the value.
870 static Value *RemoveNoopCast(Value *V) {
871 if (CastInst *CI = dyn_cast<CastInst>(V)) {
872 const Type *CTy = CI->getType();
873 const Type *OpTy = CI->getOperand(0)->getType();
874 if (CTy->isInteger() && OpTy->isInteger()) {
875 if (CTy->getPrimitiveSizeInBits() == OpTy->getPrimitiveSizeInBits())
876 return RemoveNoopCast(CI->getOperand(0));
877 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
878 return RemoveNoopCast(CI->getOperand(0));
883 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
884 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
886 if (Op0 == Op1) // sub X, X -> 0
887 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
889 // If this is a 'B = x-(-A)', change to B = x+A...
890 if (Value *V = dyn_castNegVal(Op1))
891 return BinaryOperator::createAdd(Op0, V);
893 if (isa<UndefValue>(Op0))
894 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
895 if (isa<UndefValue>(Op1))
896 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
898 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
899 // Replace (-1 - A) with (~A)...
900 if (C->isAllOnesValue())
901 return BinaryOperator::createNot(Op1);
903 // C - ~X == X + (1+C)
905 if (match(Op1, m_Not(m_Value(X))))
906 return BinaryOperator::createAdd(X,
907 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
908 // -((uint)X >> 31) -> ((int)X >> 31)
909 // -((int)X >> 31) -> ((uint)X >> 31)
910 if (C->isNullValue()) {
911 Value *NoopCastedRHS = RemoveNoopCast(Op1);
912 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
913 if (SI->getOpcode() == Instruction::Shr)
914 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
916 if (SI->getType()->isSigned())
917 NewTy = SI->getType()->getUnsignedVersion();
919 NewTy = SI->getType()->getSignedVersion();
920 // Check to see if we are shifting out everything but the sign bit.
921 if (CU->getValue() == SI->getType()->getPrimitiveSizeInBits()-1) {
922 // Ok, the transformation is safe. Insert a cast of the incoming
923 // value, then the new shift, then the new cast.
924 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
925 SI->getOperand(0)->getName());
926 Value *InV = InsertNewInstBefore(FirstCast, I);
927 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
929 if (NewShift->getType() == I.getType())
932 InV = InsertNewInstBefore(NewShift, I);
933 return new CastInst(NewShift, I.getType());
939 // Try to fold constant sub into select arguments.
940 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
941 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
944 if (isa<PHINode>(Op0))
945 if (Instruction *NV = FoldOpIntoPhi(I))
949 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
950 if (Op1I->getOpcode() == Instruction::Add &&
951 !Op0->getType()->isFloatingPoint()) {
952 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
953 return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
954 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
955 return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
956 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
957 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
958 // C1-(X+C2) --> (C1-C2)-X
959 return BinaryOperator::createSub(ConstantExpr::getSub(CI1, CI2),
960 Op1I->getOperand(0));
964 if (Op1I->hasOneUse()) {
965 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
966 // is not used by anyone else...
968 if (Op1I->getOpcode() == Instruction::Sub &&
969 !Op1I->getType()->isFloatingPoint()) {
970 // Swap the two operands of the subexpr...
971 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
972 Op1I->setOperand(0, IIOp1);
973 Op1I->setOperand(1, IIOp0);
975 // Create the new top level add instruction...
976 return BinaryOperator::createAdd(Op0, Op1);
979 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
981 if (Op1I->getOpcode() == Instruction::And &&
982 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
983 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
986 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
987 return BinaryOperator::createAnd(Op0, NewNot);
990 // -(X sdiv C) -> (X sdiv -C)
991 if (Op1I->getOpcode() == Instruction::Div)
992 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
993 if (CSI->isNullValue())
994 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
995 return BinaryOperator::createDiv(Op1I->getOperand(0),
996 ConstantExpr::getNeg(DivRHS));
998 // X - X*C --> X * (1-C)
1000 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
1002 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
1003 return BinaryOperator::createMul(Op0, CP1);
1008 if (!Op0->getType()->isFloatingPoint())
1009 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
1010 if (Op0I->getOpcode() == Instruction::Add) {
1011 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
1012 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
1013 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
1014 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
1015 } else if (Op0I->getOpcode() == Instruction::Sub) {
1016 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
1017 return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName());
1021 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
1022 if (X == Op1) { // X*C - X --> X * (C-1)
1023 Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
1024 return BinaryOperator::createMul(Op1, CP1);
1027 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
1028 if (X == dyn_castFoldableMul(Op1, C2))
1029 return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
1034 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
1035 /// really just returns true if the most significant (sign) bit is set.
1036 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
1037 if (RHS->getType()->isSigned()) {
1038 // True if source is LHS < 0 or LHS <= -1
1039 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
1040 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
1042 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
1043 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
1044 // the size of the integer type.
1045 if (Opcode == Instruction::SetGE)
1046 return RHSC->getValue() ==
1047 1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1);
1048 if (Opcode == Instruction::SetGT)
1049 return RHSC->getValue() ==
1050 (1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1))-1;
1055 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
1056 bool Changed = SimplifyCommutative(I);
1057 Value *Op0 = I.getOperand(0);
1059 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
1060 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1062 // Simplify mul instructions with a constant RHS...
1063 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
1064 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
1066 // ((X << C1)*C2) == (X * (C2 << C1))
1067 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
1068 if (SI->getOpcode() == Instruction::Shl)
1069 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
1070 return BinaryOperator::createMul(SI->getOperand(0),
1071 ConstantExpr::getShl(CI, ShOp));
1073 if (CI->isNullValue())
1074 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
1075 if (CI->equalsInt(1)) // X * 1 == X
1076 return ReplaceInstUsesWith(I, Op0);
1077 if (CI->isAllOnesValue()) // X * -1 == 0 - X
1078 return BinaryOperator::createNeg(Op0, I.getName());
1080 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
1081 if (isPowerOf2_64(Val)) { // Replace X*(2^C) with X << C
1082 uint64_t C = Log2_64(Val);
1083 return new ShiftInst(Instruction::Shl, Op0,
1084 ConstantUInt::get(Type::UByteTy, C));
1086 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
1087 if (Op1F->isNullValue())
1088 return ReplaceInstUsesWith(I, Op1);
1090 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
1091 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
1092 if (Op1F->getValue() == 1.0)
1093 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
1096 // Try to fold constant mul into select arguments.
1097 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1098 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1101 if (isa<PHINode>(Op0))
1102 if (Instruction *NV = FoldOpIntoPhi(I))
1106 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
1107 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
1108 return BinaryOperator::createMul(Op0v, Op1v);
1110 // If one of the operands of the multiply is a cast from a boolean value, then
1111 // we know the bool is either zero or one, so this is a 'masking' multiply.
1112 // See if we can simplify things based on how the boolean was originally
1114 CastInst *BoolCast = 0;
1115 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
1116 if (CI->getOperand(0)->getType() == Type::BoolTy)
1119 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
1120 if (CI->getOperand(0)->getType() == Type::BoolTy)
1123 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
1124 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
1125 const Type *SCOpTy = SCIOp0->getType();
1127 // If the setcc is true iff the sign bit of X is set, then convert this
1128 // multiply into a shift/and combination.
1129 if (isa<ConstantInt>(SCIOp1) &&
1130 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
1131 // Shift the X value right to turn it into "all signbits".
1132 Constant *Amt = ConstantUInt::get(Type::UByteTy,
1133 SCOpTy->getPrimitiveSizeInBits()-1);
1134 if (SCIOp0->getType()->isUnsigned()) {
1135 const Type *NewTy = SCIOp0->getType()->getSignedVersion();
1136 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
1137 SCIOp0->getName()), I);
1141 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
1142 BoolCast->getOperand(0)->getName()+
1145 // If the multiply type is not the same as the source type, sign extend
1146 // or truncate to the multiply type.
1147 if (I.getType() != V->getType())
1148 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
1150 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
1151 return BinaryOperator::createAnd(V, OtherOp);
1156 return Changed ? &I : 0;
1159 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
1160 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1162 if (isa<UndefValue>(Op0)) // undef / X -> 0
1163 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1164 if (isa<UndefValue>(Op1))
1165 return ReplaceInstUsesWith(I, Op1); // X / undef -> undef
1167 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1169 if (RHS->equalsInt(1))
1170 return ReplaceInstUsesWith(I, Op0);
1173 if (RHS->isAllOnesValue())
1174 return BinaryOperator::createNeg(Op0);
1176 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
1177 if (LHS->getOpcode() == Instruction::Div)
1178 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
1179 // (X / C1) / C2 -> X / (C1*C2)
1180 return BinaryOperator::createDiv(LHS->getOperand(0),
1181 ConstantExpr::getMul(RHS, LHSRHS));
1184 // Check to see if this is an unsigned division with an exact power of 2,
1185 // if so, convert to a right shift.
1186 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1187 if (uint64_t Val = C->getValue()) // Don't break X / 0
1188 if (isPowerOf2_64(Val)) {
1189 uint64_t C = Log2_64(Val);
1190 return new ShiftInst(Instruction::Shr, Op0,
1191 ConstantUInt::get(Type::UByteTy, C));
1195 if (RHS->getType()->isSigned())
1196 if (Value *LHSNeg = dyn_castNegVal(Op0))
1197 return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS));
1199 if (!RHS->isNullValue()) {
1200 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1201 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1203 if (isa<PHINode>(Op0))
1204 if (Instruction *NV = FoldOpIntoPhi(I))
1209 // If this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1210 // transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'.
1211 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1212 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1213 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1214 if (STO->getValue() == 0) { // Couldn't be this argument.
1215 I.setOperand(1, SFO);
1217 } else if (SFO->getValue() == 0) {
1218 I.setOperand(1, STO);
1222 uint64_t TVA = STO->getValue(), FVA = SFO->getValue();
1223 if (isPowerOf2_64(TVA) && isPowerOf2_64(FVA)) {
1224 unsigned TSA = Log2_64(TVA), FSA = Log2_64(FVA);
1225 Constant *TC = ConstantUInt::get(Type::UByteTy, TSA);
1226 Instruction *TSI = new ShiftInst(Instruction::Shr, Op0,
1227 TC, SI->getName()+".t");
1228 TSI = InsertNewInstBefore(TSI, I);
1230 Constant *FC = ConstantUInt::get(Type::UByteTy, FSA);
1231 Instruction *FSI = new ShiftInst(Instruction::Shr, Op0,
1232 FC, SI->getName()+".f");
1233 FSI = InsertNewInstBefore(FSI, I);
1234 return new SelectInst(SI->getOperand(0), TSI, FSI);
1238 // 0 / X == 0, we don't need to preserve faults!
1239 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1240 if (LHS->equalsInt(0))
1241 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1243 if (I.getType()->isSigned()) {
1244 // If the top bits of both operands are zero (i.e. we can prove they are
1245 // unsigned inputs), turn this into a udiv.
1246 ConstantIntegral *MaskV = ConstantSInt::getMinValue(I.getType());
1247 if (MaskedValueIsZero(Op1, MaskV) && MaskedValueIsZero(Op0, MaskV)) {
1248 const Type *NTy = Op0->getType()->getUnsignedVersion();
1249 Instruction *LHS = new CastInst(Op0, NTy, Op0->getName());
1250 InsertNewInstBefore(LHS, I);
1252 if (Constant *R = dyn_cast<Constant>(Op1))
1253 RHS = ConstantExpr::getCast(R, NTy);
1255 RHS = InsertNewInstBefore(new CastInst(Op1, NTy, Op1->getName()), I);
1256 Instruction *Div = BinaryOperator::createDiv(LHS, RHS, I.getName());
1257 InsertNewInstBefore(Div, I);
1258 return new CastInst(Div, I.getType());
1266 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
1267 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1268 if (I.getType()->isSigned()) {
1269 if (Value *RHSNeg = dyn_castNegVal(Op1))
1270 if (!isa<ConstantSInt>(RHSNeg) ||
1271 cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
1273 AddUsesToWorkList(I);
1274 I.setOperand(1, RHSNeg);
1278 // If the top bits of both operands are zero (i.e. we can prove they are
1279 // unsigned inputs), turn this into a urem.
1280 ConstantIntegral *MaskV = ConstantSInt::getMinValue(I.getType());
1281 if (MaskedValueIsZero(Op1, MaskV) && MaskedValueIsZero(Op0, MaskV)) {
1282 const Type *NTy = Op0->getType()->getUnsignedVersion();
1283 Instruction *LHS = new CastInst(Op0, NTy, Op0->getName());
1284 InsertNewInstBefore(LHS, I);
1286 if (Constant *R = dyn_cast<Constant>(Op1))
1287 RHS = ConstantExpr::getCast(R, NTy);
1289 RHS = InsertNewInstBefore(new CastInst(Op1, NTy, Op1->getName()), I);
1290 Instruction *Rem = BinaryOperator::createRem(LHS, RHS, I.getName());
1291 InsertNewInstBefore(Rem, I);
1292 return new CastInst(Rem, I.getType());
1296 if (isa<UndefValue>(Op0)) // undef % X -> 0
1297 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1298 if (isa<UndefValue>(Op1))
1299 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
1301 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1302 if (RHS->equalsInt(1)) // X % 1 == 0
1303 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1305 // Check to see if this is an unsigned remainder with an exact power of 2,
1306 // if so, convert to a bitwise and.
1307 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1308 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
1309 if (!(Val & (Val-1))) // Power of 2
1310 return BinaryOperator::createAnd(Op0,
1311 ConstantUInt::get(I.getType(), Val-1));
1313 if (!RHS->isNullValue()) {
1314 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1315 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1317 if (isa<PHINode>(Op0))
1318 if (Instruction *NV = FoldOpIntoPhi(I))
1323 // If this is 'urem X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1324 // transform this into: '(Cond ? (urem X, C1) : (urem X, C2))'.
1325 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1326 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1327 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1328 if (STO->getValue() == 0) { // Couldn't be this argument.
1329 I.setOperand(1, SFO);
1331 } else if (SFO->getValue() == 0) {
1332 I.setOperand(1, STO);
1336 if (!(STO->getValue() & (STO->getValue()-1)) &&
1337 !(SFO->getValue() & (SFO->getValue()-1))) {
1338 Value *TrueAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1339 SubOne(STO), SI->getName()+".t"), I);
1340 Value *FalseAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1341 SubOne(SFO), SI->getName()+".f"), I);
1342 return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
1346 // 0 % X == 0, we don't need to preserve faults!
1347 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1348 if (LHS->equalsInt(0))
1349 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1354 // isMaxValueMinusOne - return true if this is Max-1
1355 static bool isMaxValueMinusOne(const ConstantInt *C) {
1356 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
1357 // Calculate -1 casted to the right type...
1358 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1359 uint64_t Val = ~0ULL; // All ones
1360 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1361 return CU->getValue() == Val-1;
1364 const ConstantSInt *CS = cast<ConstantSInt>(C);
1366 // Calculate 0111111111..11111
1367 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1368 int64_t Val = INT64_MAX; // All ones
1369 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1370 return CS->getValue() == Val-1;
1373 // isMinValuePlusOne - return true if this is Min+1
1374 static bool isMinValuePlusOne(const ConstantInt *C) {
1375 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1376 return CU->getValue() == 1;
1378 const ConstantSInt *CS = cast<ConstantSInt>(C);
1380 // Calculate 1111111111000000000000
1381 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1382 int64_t Val = -1; // All ones
1383 Val <<= TypeBits-1; // Shift over to the right spot
1384 return CS->getValue() == Val+1;
1387 // isOneBitSet - Return true if there is exactly one bit set in the specified
1389 static bool isOneBitSet(const ConstantInt *CI) {
1390 uint64_t V = CI->getRawValue();
1391 return V && (V & (V-1)) == 0;
1394 #if 0 // Currently unused
1395 // isLowOnes - Return true if the constant is of the form 0+1+.
1396 static bool isLowOnes(const ConstantInt *CI) {
1397 uint64_t V = CI->getRawValue();
1399 // There won't be bits set in parts that the type doesn't contain.
1400 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1402 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1403 return U && V && (U & V) == 0;
1407 // isHighOnes - Return true if the constant is of the form 1+0+.
1408 // This is the same as lowones(~X).
1409 static bool isHighOnes(const ConstantInt *CI) {
1410 uint64_t V = ~CI->getRawValue();
1411 if (~V == 0) return false; // 0's does not match "1+"
1413 // There won't be bits set in parts that the type doesn't contain.
1414 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1416 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1417 return U && V && (U & V) == 0;
1421 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
1422 /// are carefully arranged to allow folding of expressions such as:
1424 /// (A < B) | (A > B) --> (A != B)
1426 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
1427 /// represents that the comparison is true if A == B, and bit value '1' is true
1430 static unsigned getSetCondCode(const SetCondInst *SCI) {
1431 switch (SCI->getOpcode()) {
1433 case Instruction::SetGT: return 1;
1434 case Instruction::SetEQ: return 2;
1435 case Instruction::SetGE: return 3;
1436 case Instruction::SetLT: return 4;
1437 case Instruction::SetNE: return 5;
1438 case Instruction::SetLE: return 6;
1441 assert(0 && "Invalid SetCC opcode!");
1446 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
1447 /// opcode and two operands into either a constant true or false, or a brand new
1448 /// SetCC instruction.
1449 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
1451 case 0: return ConstantBool::False;
1452 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
1453 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
1454 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
1455 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
1456 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
1457 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
1458 case 7: return ConstantBool::True;
1459 default: assert(0 && "Illegal SetCCCode!"); return 0;
1463 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1464 struct FoldSetCCLogical {
1467 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
1468 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
1469 bool shouldApply(Value *V) const {
1470 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
1471 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
1472 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
1475 Instruction *apply(BinaryOperator &Log) const {
1476 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
1477 if (SCI->getOperand(0) != LHS) {
1478 assert(SCI->getOperand(1) == LHS);
1479 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
1482 unsigned LHSCode = getSetCondCode(SCI);
1483 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
1485 switch (Log.getOpcode()) {
1486 case Instruction::And: Code = LHSCode & RHSCode; break;
1487 case Instruction::Or: Code = LHSCode | RHSCode; break;
1488 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
1489 default: assert(0 && "Illegal logical opcode!"); return 0;
1492 Value *RV = getSetCCValue(Code, LHS, RHS);
1493 if (Instruction *I = dyn_cast<Instruction>(RV))
1495 // Otherwise, it's a constant boolean value...
1496 return IC.ReplaceInstUsesWith(Log, RV);
1500 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
1501 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
1502 // guaranteed to be either a shift instruction or a binary operator.
1503 Instruction *InstCombiner::OptAndOp(Instruction *Op,
1504 ConstantIntegral *OpRHS,
1505 ConstantIntegral *AndRHS,
1506 BinaryOperator &TheAnd) {
1507 Value *X = Op->getOperand(0);
1508 Constant *Together = 0;
1509 if (!isa<ShiftInst>(Op))
1510 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
1512 switch (Op->getOpcode()) {
1513 case Instruction::Xor:
1514 if (Op->hasOneUse()) {
1515 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
1516 std::string OpName = Op->getName(); Op->setName("");
1517 Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
1518 InsertNewInstBefore(And, TheAnd);
1519 return BinaryOperator::createXor(And, Together);
1522 case Instruction::Or:
1523 if (Together == AndRHS) // (X | C) & C --> C
1524 return ReplaceInstUsesWith(TheAnd, AndRHS);
1526 if (Op->hasOneUse() && Together != OpRHS) {
1527 // (X | C1) & C2 --> (X | (C1&C2)) & C2
1528 std::string Op0Name = Op->getName(); Op->setName("");
1529 Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
1530 InsertNewInstBefore(Or, TheAnd);
1531 return BinaryOperator::createAnd(Or, AndRHS);
1534 case Instruction::Add:
1535 if (Op->hasOneUse()) {
1536 // Adding a one to a single bit bit-field should be turned into an XOR
1537 // of the bit. First thing to check is to see if this AND is with a
1538 // single bit constant.
1539 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
1541 // Clear bits that are not part of the constant.
1542 AndRHSV &= ~0ULL >> (64-AndRHS->getType()->getPrimitiveSizeInBits());
1544 // If there is only one bit set...
1545 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
1546 // Ok, at this point, we know that we are masking the result of the
1547 // ADD down to exactly one bit. If the constant we are adding has
1548 // no bits set below this bit, then we can eliminate the ADD.
1549 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
1551 // Check to see if any bits below the one bit set in AndRHSV are set.
1552 if ((AddRHS & (AndRHSV-1)) == 0) {
1553 // If not, the only thing that can effect the output of the AND is
1554 // the bit specified by AndRHSV. If that bit is set, the effect of
1555 // the XOR is to toggle the bit. If it is clear, then the ADD has
1557 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
1558 TheAnd.setOperand(0, X);
1561 std::string Name = Op->getName(); Op->setName("");
1562 // Pull the XOR out of the AND.
1563 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
1564 InsertNewInstBefore(NewAnd, TheAnd);
1565 return BinaryOperator::createXor(NewAnd, AndRHS);
1572 case Instruction::Shl: {
1573 // We know that the AND will not produce any of the bits shifted in, so if
1574 // the anded constant includes them, clear them now!
1576 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1577 Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
1578 Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
1580 if (CI == ShlMask) { // Masking out bits that the shift already masks
1581 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
1582 } else if (CI != AndRHS) { // Reducing bits set in and.
1583 TheAnd.setOperand(1, CI);
1588 case Instruction::Shr:
1589 // We know that the AND will not produce any of the bits shifted in, so if
1590 // the anded constant includes them, clear them now! This only applies to
1591 // unsigned shifts, because a signed shr may bring in set bits!
1593 if (AndRHS->getType()->isUnsigned()) {
1594 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1595 Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS);
1596 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1598 if (CI == ShrMask) { // Masking out bits that the shift already masks.
1599 return ReplaceInstUsesWith(TheAnd, Op);
1600 } else if (CI != AndRHS) {
1601 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
1604 } else { // Signed shr.
1605 // See if this is shifting in some sign extension, then masking it out
1607 if (Op->hasOneUse()) {
1608 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1609 Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS);
1610 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1611 if (CI == AndRHS) { // Masking out bits shifted in.
1612 // Make the argument unsigned.
1613 Value *ShVal = Op->getOperand(0);
1614 ShVal = InsertCastBefore(ShVal,
1615 ShVal->getType()->getUnsignedVersion(),
1617 ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal,
1618 OpRHS, Op->getName()),
1620 Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType());
1621 ShVal = InsertNewInstBefore(BinaryOperator::createAnd(ShVal, AndRHS2,
1624 return new CastInst(ShVal, Op->getType());
1634 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
1635 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
1636 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. IB is the location to
1637 /// insert new instructions.
1638 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
1639 bool Inside, Instruction &IB) {
1640 assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
1641 "Lo is not <= Hi in range emission code!");
1643 if (Lo == Hi) // Trivially false.
1644 return new SetCondInst(Instruction::SetNE, V, V);
1645 if (cast<ConstantIntegral>(Lo)->isMinValue())
1646 return new SetCondInst(Instruction::SetLT, V, Hi);
1648 Constant *AddCST = ConstantExpr::getNeg(Lo);
1649 Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
1650 InsertNewInstBefore(Add, IB);
1651 // Convert to unsigned for the comparison.
1652 const Type *UnsType = Add->getType()->getUnsignedVersion();
1653 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1654 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1655 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1656 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1659 if (Lo == Hi) // Trivially true.
1660 return new SetCondInst(Instruction::SetEQ, V, V);
1662 Hi = SubOne(cast<ConstantInt>(Hi));
1663 if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
1664 return new SetCondInst(Instruction::SetGT, V, Hi);
1666 // Emit X-Lo > Hi-Lo-1
1667 Constant *AddCST = ConstantExpr::getNeg(Lo);
1668 Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
1669 InsertNewInstBefore(Add, IB);
1670 // Convert to unsigned for the comparison.
1671 const Type *UnsType = Add->getType()->getUnsignedVersion();
1672 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1673 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1674 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1675 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1678 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
1679 // any number of 0s on either side. The 1s are allowed to wrap from LSB to
1680 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
1681 // not, since all 1s are not contiguous.
1682 static bool isRunOfOnes(ConstantIntegral *Val, unsigned &MB, unsigned &ME) {
1683 uint64_t V = Val->getRawValue();
1684 if (!isShiftedMask_64(V)) return false;
1686 // look for the first zero bit after the run of ones
1687 MB = 64-CountLeadingZeros_64((V - 1) ^ V);
1688 // look for the first non-zero bit
1689 ME = 64-CountLeadingZeros_64(V);
1695 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
1696 /// where isSub determines whether the operator is a sub. If we can fold one of
1697 /// the following xforms:
1699 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
1700 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
1701 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
1703 /// return (A +/- B).
1705 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
1706 ConstantIntegral *Mask, bool isSub,
1708 Instruction *LHSI = dyn_cast<Instruction>(LHS);
1709 if (!LHSI || LHSI->getNumOperands() != 2 ||
1710 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
1712 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
1714 switch (LHSI->getOpcode()) {
1716 case Instruction::And:
1717 if (ConstantExpr::getAnd(N, Mask) == Mask) {
1718 // If the AndRHS is a power of two minus one (0+1+), this is simple.
1719 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0)
1722 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
1723 // part, we don't need any explicit masks to take them out of A. If that
1724 // is all N is, ignore it.
1726 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
1727 Constant *Mask = ConstantInt::getAllOnesValue(RHS->getType());
1728 Mask = ConstantExpr::getUShr(Mask,
1729 ConstantInt::get(Type::UByteTy,
1731 if (MaskedValueIsZero(RHS, cast<ConstantIntegral>(Mask)))
1736 case Instruction::Or:
1737 case Instruction::Xor:
1738 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
1739 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0 &&
1740 ConstantExpr::getAnd(N, Mask)->isNullValue())
1747 New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold");
1749 New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold");
1750 return InsertNewInstBefore(New, I);
1753 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1754 bool Changed = SimplifyCommutative(I);
1755 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1757 if (isa<UndefValue>(Op1)) // X & undef -> 0
1758 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1762 return ReplaceInstUsesWith(I, Op1);
1764 if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) {
1766 if (AndRHS->isAllOnesValue())
1767 return ReplaceInstUsesWith(I, Op0);
1769 // and (and X, c1), c2 -> and (x, c1&c2). Handle this case here, before
1770 // calling MaskedValueIsZero, to avoid inefficient cases where we traipse
1771 // through many levels of ands.
1773 Value *X; ConstantInt *C1;
1774 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))))
1775 return BinaryOperator::createAnd(X, ConstantExpr::getAnd(C1, AndRHS));
1778 if (MaskedValueIsZero(Op0, AndRHS)) // LHS & RHS == 0
1779 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1781 // If the mask is not masking out any bits, there is no reason to do the
1782 // and in the first place.
1783 ConstantIntegral *NotAndRHS =
1784 cast<ConstantIntegral>(ConstantExpr::getNot(AndRHS));
1785 if (MaskedValueIsZero(Op0, NotAndRHS))
1786 return ReplaceInstUsesWith(I, Op0);
1788 // Optimize a variety of ((val OP C1) & C2) combinations...
1789 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
1790 Instruction *Op0I = cast<Instruction>(Op0);
1791 Value *Op0LHS = Op0I->getOperand(0);
1792 Value *Op0RHS = Op0I->getOperand(1);
1793 switch (Op0I->getOpcode()) {
1794 case Instruction::Xor:
1795 case Instruction::Or:
1796 // (X ^ V) & C2 --> (X & C2) iff (V & C2) == 0
1797 // (X | V) & C2 --> (X & C2) iff (V & C2) == 0
1798 if (MaskedValueIsZero(Op0LHS, AndRHS))
1799 return BinaryOperator::createAnd(Op0RHS, AndRHS);
1800 if (MaskedValueIsZero(Op0RHS, AndRHS))
1801 return BinaryOperator::createAnd(Op0LHS, AndRHS);
1803 // If the mask is only needed on one incoming arm, push it up.
1804 if (Op0I->hasOneUse()) {
1805 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
1806 // Not masking anything out for the LHS, move to RHS.
1807 Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
1808 Op0RHS->getName()+".masked");
1809 InsertNewInstBefore(NewRHS, I);
1810 return BinaryOperator::create(
1811 cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
1813 if (!isa<Constant>(NotAndRHS) &&
1814 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
1815 // Not masking anything out for the RHS, move to LHS.
1816 Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
1817 Op0LHS->getName()+".masked");
1818 InsertNewInstBefore(NewLHS, I);
1819 return BinaryOperator::create(
1820 cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
1825 case Instruction::And:
1826 // (X & V) & C2 --> 0 iff (V & C2) == 0
1827 if (MaskedValueIsZero(Op0LHS, AndRHS) ||
1828 MaskedValueIsZero(Op0RHS, AndRHS))
1829 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1831 case Instruction::Add:
1832 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
1833 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1834 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1835 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
1836 return BinaryOperator::createAnd(V, AndRHS);
1837 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
1838 return BinaryOperator::createAnd(V, AndRHS); // Add commutes
1841 case Instruction::Sub:
1842 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
1843 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1844 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1845 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
1846 return BinaryOperator::createAnd(V, AndRHS);
1850 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1851 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
1853 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
1854 const Type *SrcTy = CI->getOperand(0)->getType();
1856 // If this is an integer truncation or change from signed-to-unsigned, and
1857 // if the source is an and/or with immediate, transform it. This
1858 // frequently occurs for bitfield accesses.
1859 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
1860 if (SrcTy->getPrimitiveSizeInBits() >=
1861 I.getType()->getPrimitiveSizeInBits() &&
1862 CastOp->getNumOperands() == 2)
1863 if (ConstantInt *AndCI =dyn_cast<ConstantInt>(CastOp->getOperand(1)))
1864 if (CastOp->getOpcode() == Instruction::And) {
1865 // Change: and (cast (and X, C1) to T), C2
1866 // into : and (cast X to T), trunc(C1)&C2
1867 // This will folds the two ands together, which may allow other
1869 Instruction *NewCast =
1870 new CastInst(CastOp->getOperand(0), I.getType(),
1871 CastOp->getName()+".shrunk");
1872 NewCast = InsertNewInstBefore(NewCast, I);
1874 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1875 C3 = ConstantExpr::getAnd(C3, AndRHS); // trunc(C1)&C2
1876 return BinaryOperator::createAnd(NewCast, C3);
1877 } else if (CastOp->getOpcode() == Instruction::Or) {
1878 // Change: and (cast (or X, C1) to T), C2
1879 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
1880 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1881 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
1882 return ReplaceInstUsesWith(I, AndRHS);
1887 // If this is an integer sign or zero extension instruction.
1888 if (SrcTy->isIntegral() &&
1889 SrcTy->getPrimitiveSizeInBits() <
1890 CI->getType()->getPrimitiveSizeInBits()) {
1892 if (SrcTy->isUnsigned()) {
1893 // See if this and is clearing out bits that are known to be zero
1894 // anyway (due to the zero extension).
1895 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1896 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1897 Constant *Result = ConstantExpr::getAnd(Mask, AndRHS);
1898 if (Result == Mask) // The "and" isn't doing anything, remove it.
1899 return ReplaceInstUsesWith(I, CI);
1900 if (Result != AndRHS) { // Reduce the and RHS constant.
1901 I.setOperand(1, Result);
1906 if (CI->hasOneUse() && SrcTy->isInteger()) {
1907 // We can only do this if all of the sign bits brought in are masked
1908 // out. Compute this by first getting 0000011111, then inverting
1910 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1911 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1912 Mask = ConstantExpr::getNot(Mask); // 1's in the new bits.
1913 if (ConstantExpr::getAnd(Mask, AndRHS)->isNullValue()) {
1914 // If the and is clearing all of the sign bits, change this to a
1915 // zero extension cast. To do this, cast the cast input to
1916 // unsigned, then to the requested size.
1917 Value *CastOp = CI->getOperand(0);
1919 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
1920 CI->getName()+".uns");
1921 NC = InsertNewInstBefore(NC, I);
1922 // Finally, insert a replacement for CI.
1923 NC = new CastInst(NC, CI->getType(), CI->getName());
1925 NC = InsertNewInstBefore(NC, I);
1926 WorkList.push_back(CI); // Delete CI later.
1927 I.setOperand(0, NC);
1928 return &I; // The AND operand was modified.
1935 // Try to fold constant and into select arguments.
1936 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1937 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1939 if (isa<PHINode>(Op0))
1940 if (Instruction *NV = FoldOpIntoPhi(I))
1944 Value *Op0NotVal = dyn_castNotVal(Op0);
1945 Value *Op1NotVal = dyn_castNotVal(Op1);
1947 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1948 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1950 // (~A & ~B) == (~(A | B)) - De Morgan's Law
1951 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1952 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
1953 I.getName()+".demorgan");
1954 InsertNewInstBefore(Or, I);
1955 return BinaryOperator::createNot(Or);
1958 if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
1959 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1960 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1963 Value *LHSVal, *RHSVal;
1964 ConstantInt *LHSCst, *RHSCst;
1965 Instruction::BinaryOps LHSCC, RHSCC;
1966 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1967 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1968 if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
1969 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1970 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1971 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1972 // Ensure that the larger constant is on the RHS.
1973 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1974 SetCondInst *LHS = cast<SetCondInst>(Op0);
1975 if (cast<ConstantBool>(Cmp)->getValue()) {
1976 std::swap(LHS, RHS);
1977 std::swap(LHSCst, RHSCst);
1978 std::swap(LHSCC, RHSCC);
1981 // At this point, we know we have have two setcc instructions
1982 // comparing a value against two constants and and'ing the result
1983 // together. Because of the above check, we know that we only have
1984 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1985 // FoldSetCCLogical check above), that the two constants are not
1987 assert(LHSCst != RHSCst && "Compares not folded above?");
1990 default: assert(0 && "Unknown integer condition code!");
1991 case Instruction::SetEQ:
1993 default: assert(0 && "Unknown integer condition code!");
1994 case Instruction::SetEQ: // (X == 13 & X == 15) -> false
1995 case Instruction::SetGT: // (X == 13 & X > 15) -> false
1996 return ReplaceInstUsesWith(I, ConstantBool::False);
1997 case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
1998 case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
1999 return ReplaceInstUsesWith(I, LHS);
2001 case Instruction::SetNE:
2003 default: assert(0 && "Unknown integer condition code!");
2004 case Instruction::SetLT:
2005 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
2006 return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
2007 break; // (X != 13 & X < 15) -> no change
2008 case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
2009 case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
2010 return ReplaceInstUsesWith(I, RHS);
2011 case Instruction::SetNE:
2012 if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
2013 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2014 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
2015 LHSVal->getName()+".off");
2016 InsertNewInstBefore(Add, I);
2017 const Type *UnsType = Add->getType()->getUnsignedVersion();
2018 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
2019 AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
2020 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2021 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
2023 break; // (X != 13 & X != 15) -> no change
2026 case Instruction::SetLT:
2028 default: assert(0 && "Unknown integer condition code!");
2029 case Instruction::SetEQ: // (X < 13 & X == 15) -> false
2030 case Instruction::SetGT: // (X < 13 & X > 15) -> false
2031 return ReplaceInstUsesWith(I, ConstantBool::False);
2032 case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
2033 case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
2034 return ReplaceInstUsesWith(I, LHS);
2036 case Instruction::SetGT:
2038 default: assert(0 && "Unknown integer condition code!");
2039 case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
2040 return ReplaceInstUsesWith(I, LHS);
2041 case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
2042 return ReplaceInstUsesWith(I, RHS);
2043 case Instruction::SetNE:
2044 if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
2045 return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
2046 break; // (X > 13 & X != 15) -> no change
2047 case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
2048 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
2054 return Changed ? &I : 0;
2057 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
2058 bool Changed = SimplifyCommutative(I);
2059 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2061 if (isa<UndefValue>(Op1))
2062 return ReplaceInstUsesWith(I, // X | undef -> -1
2063 ConstantIntegral::getAllOnesValue(I.getType()));
2065 // or X, X = X or X, 0 == X
2066 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
2067 return ReplaceInstUsesWith(I, Op0);
2070 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2071 // If X is known to only contain bits that already exist in RHS, just
2072 // replace this instruction with RHS directly.
2073 if (MaskedValueIsZero(Op0,
2074 cast<ConstantIntegral>(ConstantExpr::getNot(RHS))))
2075 return ReplaceInstUsesWith(I, RHS);
2077 ConstantInt *C1; Value *X;
2078 // (X & C1) | C2 --> (X | C2) & (C1|C2)
2079 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
2080 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0->getName());
2082 InsertNewInstBefore(Or, I);
2083 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
2086 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
2087 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
2088 std::string Op0Name = Op0->getName(); Op0->setName("");
2089 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
2090 InsertNewInstBefore(Or, I);
2091 return BinaryOperator::createXor(Or,
2092 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
2095 // Try to fold constant and into select arguments.
2096 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2097 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2099 if (isa<PHINode>(Op0))
2100 if (Instruction *NV = FoldOpIntoPhi(I))
2104 Value *A, *B; ConstantInt *C1, *C2;
2106 if (match(Op0, m_And(m_Value(A), m_Value(B))))
2107 if (A == Op1 || B == Op1) // (A & ?) | A --> A
2108 return ReplaceInstUsesWith(I, Op1);
2109 if (match(Op1, m_And(m_Value(A), m_Value(B))))
2110 if (A == Op0 || B == Op0) // A | (A & ?) --> A
2111 return ReplaceInstUsesWith(I, Op0);
2113 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
2114 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2115 MaskedValueIsZero(Op1, C1)) {
2116 Instruction *NOr = BinaryOperator::createOr(A, Op1, Op0->getName());
2118 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2121 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
2122 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2123 MaskedValueIsZero(Op0, C1)) {
2124 Instruction *NOr = BinaryOperator::createOr(A, Op0, Op1->getName());
2126 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2129 // (A & C1)|(B & C2)
2130 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2131 match(Op1, m_And(m_Value(B), m_ConstantInt(C2)))) {
2133 if (A == B) // (A & C1)|(A & C2) == A & (C1|C2)
2134 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
2137 // If we have: ((V + N) & C1) | (V & C2)
2138 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
2139 // replace with V+N.
2140 if (C1 == ConstantExpr::getNot(C2)) {
2142 if ((C2->getRawValue() & (C2->getRawValue()+1)) == 0 && // C2 == 0+1+
2143 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
2144 // Add commutes, try both ways.
2145 if (V1 == B && MaskedValueIsZero(V2, C2))
2146 return ReplaceInstUsesWith(I, A);
2147 if (V2 == B && MaskedValueIsZero(V1, C2))
2148 return ReplaceInstUsesWith(I, A);
2150 // Or commutes, try both ways.
2151 if ((C1->getRawValue() & (C1->getRawValue()+1)) == 0 &&
2152 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
2153 // Add commutes, try both ways.
2154 if (V1 == A && MaskedValueIsZero(V2, C1))
2155 return ReplaceInstUsesWith(I, B);
2156 if (V2 == A && MaskedValueIsZero(V1, C1))
2157 return ReplaceInstUsesWith(I, B);
2162 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
2163 if (A == Op1) // ~A | A == -1
2164 return ReplaceInstUsesWith(I,
2165 ConstantIntegral::getAllOnesValue(I.getType()));
2169 // Note, A is still live here!
2170 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
2172 return ReplaceInstUsesWith(I,
2173 ConstantIntegral::getAllOnesValue(I.getType()));
2175 // (~A | ~B) == (~(A & B)) - De Morgan's Law
2176 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
2177 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
2178 I.getName()+".demorgan"), I);
2179 return BinaryOperator::createNot(And);
2183 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
2184 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
2185 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2188 Value *LHSVal, *RHSVal;
2189 ConstantInt *LHSCst, *RHSCst;
2190 Instruction::BinaryOps LHSCC, RHSCC;
2191 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
2192 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
2193 if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
2194 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
2195 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
2196 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
2197 // Ensure that the larger constant is on the RHS.
2198 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
2199 SetCondInst *LHS = cast<SetCondInst>(Op0);
2200 if (cast<ConstantBool>(Cmp)->getValue()) {
2201 std::swap(LHS, RHS);
2202 std::swap(LHSCst, RHSCst);
2203 std::swap(LHSCC, RHSCC);
2206 // At this point, we know we have have two setcc instructions
2207 // comparing a value against two constants and or'ing the result
2208 // together. Because of the above check, we know that we only have
2209 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
2210 // FoldSetCCLogical check above), that the two constants are not
2212 assert(LHSCst != RHSCst && "Compares not folded above?");
2215 default: assert(0 && "Unknown integer condition code!");
2216 case Instruction::SetEQ:
2218 default: assert(0 && "Unknown integer condition code!");
2219 case Instruction::SetEQ:
2220 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
2221 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2222 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
2223 LHSVal->getName()+".off");
2224 InsertNewInstBefore(Add, I);
2225 const Type *UnsType = Add->getType()->getUnsignedVersion();
2226 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
2227 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
2228 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2229 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
2231 break; // (X == 13 | X == 15) -> no change
2233 case Instruction::SetGT: // (X == 13 | X > 14) -> no change
2235 case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
2236 case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
2237 return ReplaceInstUsesWith(I, RHS);
2240 case Instruction::SetNE:
2242 default: assert(0 && "Unknown integer condition code!");
2243 case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
2244 case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
2245 return ReplaceInstUsesWith(I, LHS);
2246 case Instruction::SetNE: // (X != 13 | X != 15) -> true
2247 case Instruction::SetLT: // (X != 13 | X < 15) -> true
2248 return ReplaceInstUsesWith(I, ConstantBool::True);
2251 case Instruction::SetLT:
2253 default: assert(0 && "Unknown integer condition code!");
2254 case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
2256 case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
2257 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
2258 case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
2259 case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
2260 return ReplaceInstUsesWith(I, RHS);
2263 case Instruction::SetGT:
2265 default: assert(0 && "Unknown integer condition code!");
2266 case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
2267 case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
2268 return ReplaceInstUsesWith(I, LHS);
2269 case Instruction::SetNE: // (X > 13 | X != 15) -> true
2270 case Instruction::SetLT: // (X > 13 | X < 15) -> true
2271 return ReplaceInstUsesWith(I, ConstantBool::True);
2277 return Changed ? &I : 0;
2280 // XorSelf - Implements: X ^ X --> 0
2283 XorSelf(Value *rhs) : RHS(rhs) {}
2284 bool shouldApply(Value *LHS) const { return LHS == RHS; }
2285 Instruction *apply(BinaryOperator &Xor) const {
2291 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
2292 bool Changed = SimplifyCommutative(I);
2293 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2295 if (isa<UndefValue>(Op1))
2296 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
2298 // xor X, X = 0, even if X is nested in a sequence of Xor's.
2299 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
2300 assert(Result == &I && "AssociativeOpt didn't work?");
2301 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2304 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2306 if (RHS->isNullValue())
2307 return ReplaceInstUsesWith(I, Op0);
2309 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2310 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
2311 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
2312 if (RHS == ConstantBool::True && SCI->hasOneUse())
2313 return new SetCondInst(SCI->getInverseCondition(),
2314 SCI->getOperand(0), SCI->getOperand(1));
2316 // ~(c-X) == X-c-1 == X+(-c-1)
2317 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
2318 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
2319 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
2320 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
2321 ConstantInt::get(I.getType(), 1));
2322 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
2325 // ~(~X & Y) --> (X | ~Y)
2326 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
2327 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
2328 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
2330 BinaryOperator::createNot(Op0I->getOperand(1),
2331 Op0I->getOperand(1)->getName()+".not");
2332 InsertNewInstBefore(NotY, I);
2333 return BinaryOperator::createOr(Op0NotVal, NotY);
2337 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
2338 switch (Op0I->getOpcode()) {
2339 case Instruction::Add:
2340 // ~(X-c) --> (-c-1)-X
2341 if (RHS->isAllOnesValue()) {
2342 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
2343 return BinaryOperator::createSub(
2344 ConstantExpr::getSub(NegOp0CI,
2345 ConstantInt::get(I.getType(), 1)),
2346 Op0I->getOperand(0));
2349 case Instruction::And:
2350 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
2351 if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue())
2352 return BinaryOperator::createOr(Op0, RHS);
2354 case Instruction::Or:
2355 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
2356 if (ConstantExpr::getAnd(RHS, Op0CI) == RHS)
2357 return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS));
2363 // Try to fold constant and into select arguments.
2364 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2365 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2367 if (isa<PHINode>(Op0))
2368 if (Instruction *NV = FoldOpIntoPhi(I))
2372 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
2374 return ReplaceInstUsesWith(I,
2375 ConstantIntegral::getAllOnesValue(I.getType()));
2377 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
2379 return ReplaceInstUsesWith(I,
2380 ConstantIntegral::getAllOnesValue(I.getType()));
2382 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
2383 if (Op1I->getOpcode() == Instruction::Or) {
2384 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
2385 cast<BinaryOperator>(Op1I)->swapOperands();
2387 std::swap(Op0, Op1);
2388 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
2390 std::swap(Op0, Op1);
2392 } else if (Op1I->getOpcode() == Instruction::Xor) {
2393 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
2394 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
2395 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
2396 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
2399 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
2400 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
2401 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
2402 cast<BinaryOperator>(Op0I)->swapOperands();
2403 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
2404 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
2405 Op1->getName()+".not"), I);
2406 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
2408 } else if (Op0I->getOpcode() == Instruction::Xor) {
2409 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
2410 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2411 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
2412 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2415 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
2416 Value *A, *B; ConstantInt *C1, *C2;
2417 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2418 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) &&
2419 ConstantExpr::getAnd(C1, C2)->isNullValue())
2420 return BinaryOperator::createOr(Op0, Op1);
2422 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
2423 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
2424 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2427 return Changed ? &I : 0;
2430 /// MulWithOverflow - Compute Result = In1*In2, returning true if the result
2431 /// overflowed for this type.
2432 static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2434 Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
2435 return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
2438 static bool isPositive(ConstantInt *C) {
2439 return cast<ConstantSInt>(C)->getValue() >= 0;
2442 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
2443 /// overflowed for this type.
2444 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2446 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
2448 if (In1->getType()->isUnsigned())
2449 return cast<ConstantUInt>(Result)->getValue() <
2450 cast<ConstantUInt>(In1)->getValue();
2451 if (isPositive(In1) != isPositive(In2))
2453 if (isPositive(In1))
2454 return cast<ConstantSInt>(Result)->getValue() <
2455 cast<ConstantSInt>(In1)->getValue();
2456 return cast<ConstantSInt>(Result)->getValue() >
2457 cast<ConstantSInt>(In1)->getValue();
2460 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
2461 /// code necessary to compute the offset from the base pointer (without adding
2462 /// in the base pointer). Return the result as a signed integer of intptr size.
2463 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
2464 TargetData &TD = IC.getTargetData();
2465 gep_type_iterator GTI = gep_type_begin(GEP);
2466 const Type *UIntPtrTy = TD.getIntPtrType();
2467 const Type *SIntPtrTy = UIntPtrTy->getSignedVersion();
2468 Value *Result = Constant::getNullValue(SIntPtrTy);
2470 // Build a mask for high order bits.
2471 uint64_t PtrSizeMask = ~0ULL;
2472 PtrSizeMask >>= 64-(TD.getPointerSize()*8);
2474 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
2475 Value *Op = GEP->getOperand(i);
2476 uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask;
2477 Constant *Scale = ConstantExpr::getCast(ConstantUInt::get(UIntPtrTy, Size),
2479 if (Constant *OpC = dyn_cast<Constant>(Op)) {
2480 if (!OpC->isNullValue()) {
2481 OpC = ConstantExpr::getCast(OpC, SIntPtrTy);
2482 Scale = ConstantExpr::getMul(OpC, Scale);
2483 if (Constant *RC = dyn_cast<Constant>(Result))
2484 Result = ConstantExpr::getAdd(RC, Scale);
2486 // Emit an add instruction.
2487 Result = IC.InsertNewInstBefore(
2488 BinaryOperator::createAdd(Result, Scale,
2489 GEP->getName()+".offs"), I);
2493 // Convert to correct type.
2494 Op = IC.InsertNewInstBefore(new CastInst(Op, SIntPtrTy,
2495 Op->getName()+".c"), I);
2497 // We'll let instcombine(mul) convert this to a shl if possible.
2498 Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
2499 GEP->getName()+".idx"), I);
2501 // Emit an add instruction.
2502 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
2503 GEP->getName()+".offs"), I);
2509 /// FoldGEPSetCC - Fold comparisons between a GEP instruction and something
2510 /// else. At this point we know that the GEP is on the LHS of the comparison.
2511 Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS,
2512 Instruction::BinaryOps Cond,
2514 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
2516 if (CastInst *CI = dyn_cast<CastInst>(RHS))
2517 if (isa<PointerType>(CI->getOperand(0)->getType()))
2518 RHS = CI->getOperand(0);
2520 Value *PtrBase = GEPLHS->getOperand(0);
2521 if (PtrBase == RHS) {
2522 // As an optimization, we don't actually have to compute the actual value of
2523 // OFFSET if this is a seteq or setne comparison, just return whether each
2524 // index is zero or not.
2525 if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) {
2526 Instruction *InVal = 0;
2527 gep_type_iterator GTI = gep_type_begin(GEPLHS);
2528 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
2530 if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
2531 if (isa<UndefValue>(C)) // undef index -> undef.
2532 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
2533 if (C->isNullValue())
2535 else if (TD->getTypeSize(GTI.getIndexedType()) == 0) {
2536 EmitIt = false; // This is indexing into a zero sized array?
2537 } else if (isa<ConstantInt>(C))
2538 return ReplaceInstUsesWith(I, // No comparison is needed here.
2539 ConstantBool::get(Cond == Instruction::SetNE));
2544 new SetCondInst(Cond, GEPLHS->getOperand(i),
2545 Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
2549 InVal = InsertNewInstBefore(InVal, I);
2550 InsertNewInstBefore(Comp, I);
2551 if (Cond == Instruction::SetNE) // True if any are unequal
2552 InVal = BinaryOperator::createOr(InVal, Comp);
2553 else // True if all are equal
2554 InVal = BinaryOperator::createAnd(InVal, Comp);
2562 ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0
2563 ConstantBool::get(Cond == Instruction::SetEQ));
2566 // Only lower this if the setcc is the only user of the GEP or if we expect
2567 // the result to fold to a constant!
2568 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
2569 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
2570 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
2571 return new SetCondInst(Cond, Offset,
2572 Constant::getNullValue(Offset->getType()));
2574 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
2575 // If the base pointers are different, but the indices are the same, just
2576 // compare the base pointer.
2577 if (PtrBase != GEPRHS->getOperand(0)) {
2578 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
2579 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
2580 GEPRHS->getOperand(0)->getType();
2582 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2583 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2584 IndicesTheSame = false;
2588 // If all indices are the same, just compare the base pointers.
2590 return new SetCondInst(Cond, GEPLHS->getOperand(0),
2591 GEPRHS->getOperand(0));
2593 // Otherwise, the base pointers are different and the indices are
2594 // different, bail out.
2598 // If one of the GEPs has all zero indices, recurse.
2599 bool AllZeros = true;
2600 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2601 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
2602 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
2607 return FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0),
2608 SetCondInst::getSwappedCondition(Cond), I);
2610 // If the other GEP has all zero indices, recurse.
2612 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2613 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
2614 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
2619 return FoldGEPSetCC(GEPLHS, GEPRHS->getOperand(0), Cond, I);
2621 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
2622 // If the GEPs only differ by one index, compare it.
2623 unsigned NumDifferences = 0; // Keep track of # differences.
2624 unsigned DiffOperand = 0; // The operand that differs.
2625 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2626 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2627 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
2628 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
2629 // Irreconcilable differences.
2633 if (NumDifferences++) break;
2638 if (NumDifferences == 0) // SAME GEP?
2639 return ReplaceInstUsesWith(I, // No comparison is needed here.
2640 ConstantBool::get(Cond == Instruction::SetEQ));
2641 else if (NumDifferences == 1) {
2642 Value *LHSV = GEPLHS->getOperand(DiffOperand);
2643 Value *RHSV = GEPRHS->getOperand(DiffOperand);
2645 // Convert the operands to signed values to make sure to perform a
2646 // signed comparison.
2647 const Type *NewTy = LHSV->getType()->getSignedVersion();
2648 if (LHSV->getType() != NewTy)
2649 LHSV = InsertNewInstBefore(new CastInst(LHSV, NewTy,
2650 LHSV->getName()), I);
2651 if (RHSV->getType() != NewTy)
2652 RHSV = InsertNewInstBefore(new CastInst(RHSV, NewTy,
2653 RHSV->getName()), I);
2654 return new SetCondInst(Cond, LHSV, RHSV);
2658 // Only lower this if the setcc is the only user of the GEP or if we expect
2659 // the result to fold to a constant!
2660 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
2661 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
2662 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
2663 Value *L = EmitGEPOffset(GEPLHS, I, *this);
2664 Value *R = EmitGEPOffset(GEPRHS, I, *this);
2665 return new SetCondInst(Cond, L, R);
2672 Instruction *InstCombiner::visitSetCondInst(SetCondInst &I) {
2673 bool Changed = SimplifyCommutative(I);
2674 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2675 const Type *Ty = Op0->getType();
2679 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
2681 if (isa<UndefValue>(Op1)) // X setcc undef -> undef
2682 return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
2684 // setcc <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
2685 // addresses never equal each other! We already know that Op0 != Op1.
2686 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
2687 isa<ConstantPointerNull>(Op0)) &&
2688 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
2689 isa<ConstantPointerNull>(Op1)))
2690 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
2692 // setcc's with boolean values can always be turned into bitwise operations
2693 if (Ty == Type::BoolTy) {
2694 switch (I.getOpcode()) {
2695 default: assert(0 && "Invalid setcc instruction!");
2696 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
2697 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
2698 InsertNewInstBefore(Xor, I);
2699 return BinaryOperator::createNot(Xor);
2701 case Instruction::SetNE:
2702 return BinaryOperator::createXor(Op0, Op1);
2704 case Instruction::SetGT:
2705 std::swap(Op0, Op1); // Change setgt -> setlt
2707 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
2708 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2709 InsertNewInstBefore(Not, I);
2710 return BinaryOperator::createAnd(Not, Op1);
2712 case Instruction::SetGE:
2713 std::swap(Op0, Op1); // Change setge -> setle
2715 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
2716 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2717 InsertNewInstBefore(Not, I);
2718 return BinaryOperator::createOr(Not, Op1);
2723 // See if we are doing a comparison between a constant and an instruction that
2724 // can be folded into the comparison.
2725 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2726 // Check to see if we are comparing against the minimum or maximum value...
2727 if (CI->isMinValue()) {
2728 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
2729 return ReplaceInstUsesWith(I, ConstantBool::False);
2730 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
2731 return ReplaceInstUsesWith(I, ConstantBool::True);
2732 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
2733 return BinaryOperator::createSetEQ(Op0, Op1);
2734 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
2735 return BinaryOperator::createSetNE(Op0, Op1);
2737 } else if (CI->isMaxValue()) {
2738 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
2739 return ReplaceInstUsesWith(I, ConstantBool::False);
2740 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
2741 return ReplaceInstUsesWith(I, ConstantBool::True);
2742 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
2743 return BinaryOperator::createSetEQ(Op0, Op1);
2744 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
2745 return BinaryOperator::createSetNE(Op0, Op1);
2747 // Comparing against a value really close to min or max?
2748 } else if (isMinValuePlusOne(CI)) {
2749 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
2750 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
2751 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
2752 return BinaryOperator::createSetNE(Op0, SubOne(CI));
2754 } else if (isMaxValueMinusOne(CI)) {
2755 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
2756 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
2757 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
2758 return BinaryOperator::createSetNE(Op0, AddOne(CI));
2761 // If we still have a setle or setge instruction, turn it into the
2762 // appropriate setlt or setgt instruction. Since the border cases have
2763 // already been handled above, this requires little checking.
2765 if (I.getOpcode() == Instruction::SetLE)
2766 return BinaryOperator::createSetLT(Op0, AddOne(CI));
2767 if (I.getOpcode() == Instruction::SetGE)
2768 return BinaryOperator::createSetGT(Op0, SubOne(CI));
2770 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
2771 switch (LHSI->getOpcode()) {
2772 case Instruction::And:
2773 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
2774 LHSI->getOperand(0)->hasOneUse()) {
2775 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
2776 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
2777 // happens a LOT in code produced by the C front-end, for bitfield
2779 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
2780 ConstantUInt *ShAmt;
2781 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
2782 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
2783 const Type *Ty = LHSI->getType();
2785 // We can fold this as long as we can't shift unknown bits
2786 // into the mask. This can only happen with signed shift
2787 // rights, as they sign-extend.
2789 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
2790 Shift->getType()->isUnsigned();
2792 // To test for the bad case of the signed shr, see if any
2793 // of the bits shifted in could be tested after the mask.
2794 int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue();
2795 if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
2797 Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal);
2799 ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
2800 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
2806 if (Shift->getOpcode() == Instruction::Shl)
2807 NewCst = ConstantExpr::getUShr(CI, ShAmt);
2809 NewCst = ConstantExpr::getShl(CI, ShAmt);
2811 // Check to see if we are shifting out any of the bits being
2813 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
2814 // If we shifted bits out, the fold is not going to work out.
2815 // As a special case, check to see if this means that the
2816 // result is always true or false now.
2817 if (I.getOpcode() == Instruction::SetEQ)
2818 return ReplaceInstUsesWith(I, ConstantBool::False);
2819 if (I.getOpcode() == Instruction::SetNE)
2820 return ReplaceInstUsesWith(I, ConstantBool::True);
2822 I.setOperand(1, NewCst);
2823 Constant *NewAndCST;
2824 if (Shift->getOpcode() == Instruction::Shl)
2825 NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
2827 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
2828 LHSI->setOperand(1, NewAndCST);
2829 LHSI->setOperand(0, Shift->getOperand(0));
2830 WorkList.push_back(Shift); // Shift is dead.
2831 AddUsesToWorkList(I);
2839 case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
2840 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2841 switch (I.getOpcode()) {
2843 case Instruction::SetEQ:
2844 case Instruction::SetNE: {
2845 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2847 // Check that the shift amount is in range. If not, don't perform
2848 // undefined shifts. When the shift is visited it will be
2850 if (ShAmt->getValue() >= TypeBits)
2853 // If we are comparing against bits always shifted out, the
2854 // comparison cannot succeed.
2856 ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
2857 if (Comp != CI) {// Comparing against a bit that we know is zero.
2858 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2859 Constant *Cst = ConstantBool::get(IsSetNE);
2860 return ReplaceInstUsesWith(I, Cst);
2863 if (LHSI->hasOneUse()) {
2864 // Otherwise strength reduce the shift into an and.
2865 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2866 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
2869 if (CI->getType()->isUnsigned()) {
2870 Mask = ConstantUInt::get(CI->getType(), Val);
2871 } else if (ShAmtVal != 0) {
2872 Mask = ConstantSInt::get(CI->getType(), Val);
2874 Mask = ConstantInt::getAllOnesValue(CI->getType());
2878 BinaryOperator::createAnd(LHSI->getOperand(0),
2879 Mask, LHSI->getName()+".mask");
2880 Value *And = InsertNewInstBefore(AndI, I);
2881 return new SetCondInst(I.getOpcode(), And,
2882 ConstantExpr::getUShr(CI, ShAmt));
2889 case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
2890 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2891 switch (I.getOpcode()) {
2893 case Instruction::SetEQ:
2894 case Instruction::SetNE: {
2896 // Check that the shift amount is in range. If not, don't perform
2897 // undefined shifts. When the shift is visited it will be
2899 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2900 if (ShAmt->getValue() >= TypeBits)
2903 // If we are comparing against bits always shifted out, the
2904 // comparison cannot succeed.
2906 ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
2908 if (Comp != CI) {// Comparing against a bit that we know is zero.
2909 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2910 Constant *Cst = ConstantBool::get(IsSetNE);
2911 return ReplaceInstUsesWith(I, Cst);
2914 if (LHSI->hasOneUse() || CI->isNullValue()) {
2915 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2917 // Otherwise strength reduce the shift into an and.
2918 uint64_t Val = ~0ULL; // All ones.
2919 Val <<= ShAmtVal; // Shift over to the right spot.
2922 if (CI->getType()->isUnsigned()) {
2923 Val &= ~0ULL >> (64-TypeBits);
2924 Mask = ConstantUInt::get(CI->getType(), Val);
2926 Mask = ConstantSInt::get(CI->getType(), Val);
2930 BinaryOperator::createAnd(LHSI->getOperand(0),
2931 Mask, LHSI->getName()+".mask");
2932 Value *And = InsertNewInstBefore(AndI, I);
2933 return new SetCondInst(I.getOpcode(), And,
2934 ConstantExpr::getShl(CI, ShAmt));
2942 case Instruction::Div:
2943 // Fold: (div X, C1) op C2 -> range check
2944 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
2945 // Fold this div into the comparison, producing a range check.
2946 // Determine, based on the divide type, what the range is being
2947 // checked. If there is an overflow on the low or high side, remember
2948 // it, otherwise compute the range [low, hi) bounding the new value.
2949 bool LoOverflow = false, HiOverflow = 0;
2950 ConstantInt *LoBound = 0, *HiBound = 0;
2953 bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
2955 Instruction::BinaryOps Opcode = I.getOpcode();
2957 if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
2958 } else if (LHSI->getType()->isUnsigned()) { // udiv
2960 LoOverflow = ProdOV;
2961 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
2962 } else if (isPositive(DivRHS)) { // Divisor is > 0.
2963 if (CI->isNullValue()) { // (X / pos) op 0
2965 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
2967 } else if (isPositive(CI)) { // (X / pos) op pos
2969 LoOverflow = ProdOV;
2970 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
2971 } else { // (X / pos) op neg
2972 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
2973 LoOverflow = AddWithOverflow(LoBound, Prod,
2974 cast<ConstantInt>(DivRHSH));
2976 HiOverflow = ProdOV;
2978 } else { // Divisor is < 0.
2979 if (CI->isNullValue()) { // (X / neg) op 0
2980 LoBound = AddOne(DivRHS);
2981 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
2982 if (HiBound == DivRHS)
2983 LoBound = 0; // - INTMIN = INTMIN
2984 } else if (isPositive(CI)) { // (X / neg) op pos
2985 HiOverflow = LoOverflow = ProdOV;
2987 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
2988 HiBound = AddOne(Prod);
2989 } else { // (X / neg) op neg
2991 LoOverflow = HiOverflow = ProdOV;
2992 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
2995 // Dividing by a negate swaps the condition.
2996 Opcode = SetCondInst::getSwappedCondition(Opcode);
3000 Value *X = LHSI->getOperand(0);
3002 default: assert(0 && "Unhandled setcc opcode!");
3003 case Instruction::SetEQ:
3004 if (LoOverflow && HiOverflow)
3005 return ReplaceInstUsesWith(I, ConstantBool::False);
3006 else if (HiOverflow)
3007 return new SetCondInst(Instruction::SetGE, X, LoBound);
3008 else if (LoOverflow)
3009 return new SetCondInst(Instruction::SetLT, X, HiBound);
3011 return InsertRangeTest(X, LoBound, HiBound, true, I);
3012 case Instruction::SetNE:
3013 if (LoOverflow && HiOverflow)
3014 return ReplaceInstUsesWith(I, ConstantBool::True);
3015 else if (HiOverflow)
3016 return new SetCondInst(Instruction::SetLT, X, LoBound);
3017 else if (LoOverflow)
3018 return new SetCondInst(Instruction::SetGE, X, HiBound);
3020 return InsertRangeTest(X, LoBound, HiBound, false, I);
3021 case Instruction::SetLT:
3023 return ReplaceInstUsesWith(I, ConstantBool::False);
3024 return new SetCondInst(Instruction::SetLT, X, LoBound);
3025 case Instruction::SetGT:
3027 return ReplaceInstUsesWith(I, ConstantBool::False);
3028 return new SetCondInst(Instruction::SetGE, X, HiBound);
3035 // Simplify seteq and setne instructions...
3036 if (I.getOpcode() == Instruction::SetEQ ||
3037 I.getOpcode() == Instruction::SetNE) {
3038 bool isSetNE = I.getOpcode() == Instruction::SetNE;
3040 // If the first operand is (and|or|xor) with a constant, and the second
3041 // operand is a constant, simplify a bit.
3042 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
3043 switch (BO->getOpcode()) {
3044 case Instruction::Rem:
3045 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
3046 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
3048 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1) {
3049 int64_t V = cast<ConstantSInt>(BO->getOperand(1))->getValue();
3050 if (isPowerOf2_64(V)) {
3051 unsigned L2 = Log2_64(V);
3052 const Type *UTy = BO->getType()->getUnsignedVersion();
3053 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
3055 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
3056 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
3057 RHSCst, BO->getName()), I);
3058 return BinaryOperator::create(I.getOpcode(), NewRem,
3059 Constant::getNullValue(UTy));
3064 case Instruction::Add:
3065 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
3066 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3067 if (BO->hasOneUse())
3068 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
3069 ConstantExpr::getSub(CI, BOp1C));
3070 } else if (CI->isNullValue()) {
3071 // Replace ((add A, B) != 0) with (A != -B) if A or B is
3072 // efficiently invertible, or if the add has just this one use.
3073 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
3075 if (Value *NegVal = dyn_castNegVal(BOp1))
3076 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
3077 else if (Value *NegVal = dyn_castNegVal(BOp0))
3078 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
3079 else if (BO->hasOneUse()) {
3080 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
3082 InsertNewInstBefore(Neg, I);
3083 return new SetCondInst(I.getOpcode(), BOp0, Neg);
3087 case Instruction::Xor:
3088 // For the xor case, we can xor two constants together, eliminating
3089 // the explicit xor.
3090 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
3091 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
3092 ConstantExpr::getXor(CI, BOC));
3095 case Instruction::Sub:
3096 // Replace (([sub|xor] A, B) != 0) with (A != B)
3097 if (CI->isNullValue())
3098 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
3102 case Instruction::Or:
3103 // If bits are being or'd in that are not present in the constant we
3104 // are comparing against, then the comparison could never succeed!
3105 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
3106 Constant *NotCI = ConstantExpr::getNot(CI);
3107 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
3108 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3112 case Instruction::And:
3113 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3114 // If bits are being compared against that are and'd out, then the
3115 // comparison can never succeed!
3116 if (!ConstantExpr::getAnd(CI,
3117 ConstantExpr::getNot(BOC))->isNullValue())
3118 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3120 // If we have ((X & C) == C), turn it into ((X & C) != 0).
3121 if (CI == BOC && isOneBitSet(CI))
3122 return new SetCondInst(isSetNE ? Instruction::SetEQ :
3123 Instruction::SetNE, Op0,
3124 Constant::getNullValue(CI->getType()));
3126 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
3127 // to be a signed value as appropriate.
3128 if (isSignBit(BOC)) {
3129 Value *X = BO->getOperand(0);
3130 // If 'X' is not signed, insert a cast now...
3131 if (!BOC->getType()->isSigned()) {
3132 const Type *DestTy = BOC->getType()->getSignedVersion();
3133 X = InsertCastBefore(X, DestTy, I);
3135 return new SetCondInst(isSetNE ? Instruction::SetLT :
3136 Instruction::SetGE, X,
3137 Constant::getNullValue(X->getType()));
3140 // ((X & ~7) == 0) --> X < 8
3141 if (CI->isNullValue() && isHighOnes(BOC)) {
3142 Value *X = BO->getOperand(0);
3143 Constant *NegX = ConstantExpr::getNeg(BOC);
3145 // If 'X' is signed, insert a cast now.
3146 if (NegX->getType()->isSigned()) {
3147 const Type *DestTy = NegX->getType()->getUnsignedVersion();
3148 X = InsertCastBefore(X, DestTy, I);
3149 NegX = ConstantExpr::getCast(NegX, DestTy);
3152 return new SetCondInst(isSetNE ? Instruction::SetGE :
3153 Instruction::SetLT, X, NegX);
3160 } else { // Not a SetEQ/SetNE
3161 // If the LHS is a cast from an integral value of the same size,
3162 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
3163 Value *CastOp = Cast->getOperand(0);
3164 const Type *SrcTy = CastOp->getType();
3165 unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits();
3166 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
3167 SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
3168 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
3169 "Source and destination signednesses should differ!");
3170 if (Cast->getType()->isSigned()) {
3171 // If this is a signed comparison, check for comparisons in the
3172 // vicinity of zero.
3173 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
3175 return BinaryOperator::createSetGT(CastOp,
3176 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize-1))-1));
3177 else if (I.getOpcode() == Instruction::SetGT &&
3178 cast<ConstantSInt>(CI)->getValue() == -1)
3179 // X > -1 => x < 128
3180 return BinaryOperator::createSetLT(CastOp,
3181 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize-1)));
3183 ConstantUInt *CUI = cast<ConstantUInt>(CI);
3184 if (I.getOpcode() == Instruction::SetLT &&
3185 CUI->getValue() == 1ULL << (SrcTySize-1))
3186 // X < 128 => X > -1
3187 return BinaryOperator::createSetGT(CastOp,
3188 ConstantSInt::get(SrcTy, -1));
3189 else if (I.getOpcode() == Instruction::SetGT &&
3190 CUI->getValue() == (1ULL << (SrcTySize-1))-1)
3192 return BinaryOperator::createSetLT(CastOp,
3193 Constant::getNullValue(SrcTy));
3200 // Handle setcc with constant RHS's that can be integer, FP or pointer.
3201 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
3202 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3203 switch (LHSI->getOpcode()) {
3204 case Instruction::GetElementPtr:
3205 if (RHSC->isNullValue()) {
3206 // Transform setcc GEP P, int 0, int 0, int 0, null -> setcc P, null
3207 bool isAllZeros = true;
3208 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
3209 if (!isa<Constant>(LHSI->getOperand(i)) ||
3210 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
3215 return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),
3216 Constant::getNullValue(LHSI->getOperand(0)->getType()));
3220 case Instruction::PHI:
3221 if (Instruction *NV = FoldOpIntoPhi(I))
3224 case Instruction::Select:
3225 // If either operand of the select is a constant, we can fold the
3226 // comparison into the select arms, which will cause one to be
3227 // constant folded and the select turned into a bitwise or.
3228 Value *Op1 = 0, *Op2 = 0;
3229 if (LHSI->hasOneUse()) {
3230 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
3231 // Fold the known value into the constant operand.
3232 Op1 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3233 // Insert a new SetCC of the other select operand.
3234 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3235 LHSI->getOperand(2), RHSC,
3237 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
3238 // Fold the known value into the constant operand.
3239 Op2 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3240 // Insert a new SetCC of the other select operand.
3241 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3242 LHSI->getOperand(1), RHSC,
3248 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
3253 // If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now.
3254 if (User *GEP = dyn_castGetElementPtr(Op0))
3255 if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I))
3257 if (User *GEP = dyn_castGetElementPtr(Op1))
3258 if (Instruction *NI = FoldGEPSetCC(GEP, Op0,
3259 SetCondInst::getSwappedCondition(I.getOpcode()), I))
3262 // Test to see if the operands of the setcc are casted versions of other
3263 // values. If the cast can be stripped off both arguments, we do so now.
3264 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3265 Value *CastOp0 = CI->getOperand(0);
3266 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
3267 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
3268 (I.getOpcode() == Instruction::SetEQ ||
3269 I.getOpcode() == Instruction::SetNE)) {
3270 // We keep moving the cast from the left operand over to the right
3271 // operand, where it can often be eliminated completely.
3274 // If operand #1 is a cast instruction, see if we can eliminate it as
3276 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
3277 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
3279 Op1 = CI2->getOperand(0);
3281 // If Op1 is a constant, we can fold the cast into the constant.
3282 if (Op1->getType() != Op0->getType())
3283 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
3284 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
3286 // Otherwise, cast the RHS right before the setcc
3287 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
3288 InsertNewInstBefore(cast<Instruction>(Op1), I);
3290 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
3293 // Handle the special case of: setcc (cast bool to X), <cst>
3294 // This comes up when you have code like
3297 // For generality, we handle any zero-extension of any operand comparison
3298 // with a constant or another cast from the same type.
3299 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
3300 if (Instruction *R = visitSetCondInstWithCastAndCast(I))
3303 return Changed ? &I : 0;
3306 // visitSetCondInstWithCastAndCast - Handle setcond (cast x to y), (cast/cst).
3307 // We only handle extending casts so far.
3309 Instruction *InstCombiner::visitSetCondInstWithCastAndCast(SetCondInst &SCI) {
3310 Value *LHSCIOp = cast<CastInst>(SCI.getOperand(0))->getOperand(0);
3311 const Type *SrcTy = LHSCIOp->getType();
3312 const Type *DestTy = SCI.getOperand(0)->getType();
3315 if (!DestTy->isIntegral() || !SrcTy->isIntegral())
3318 unsigned SrcBits = SrcTy->getPrimitiveSizeInBits();
3319 unsigned DestBits = DestTy->getPrimitiveSizeInBits();
3320 if (SrcBits >= DestBits) return 0; // Only handle extending cast.
3322 // Is this a sign or zero extension?
3323 bool isSignSrc = SrcTy->isSigned();
3324 bool isSignDest = DestTy->isSigned();
3326 if (CastInst *CI = dyn_cast<CastInst>(SCI.getOperand(1))) {
3327 // Not an extension from the same type?
3328 RHSCIOp = CI->getOperand(0);
3329 if (RHSCIOp->getType() != LHSCIOp->getType()) return 0;
3330 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(SCI.getOperand(1))) {
3331 // Compute the constant that would happen if we truncated to SrcTy then
3332 // reextended to DestTy.
3333 Constant *Res = ConstantExpr::getCast(CI, SrcTy);
3335 if (ConstantExpr::getCast(Res, DestTy) == CI) {
3338 // If the value cannot be represented in the shorter type, we cannot emit
3339 // a simple comparison.
3340 if (SCI.getOpcode() == Instruction::SetEQ)
3341 return ReplaceInstUsesWith(SCI, ConstantBool::False);
3342 if (SCI.getOpcode() == Instruction::SetNE)
3343 return ReplaceInstUsesWith(SCI, ConstantBool::True);
3345 // Evaluate the comparison for LT.
3347 if (DestTy->isSigned()) {
3348 // We're performing a signed comparison.
3350 // Signed extend and signed comparison.
3351 if (cast<ConstantSInt>(CI)->getValue() < 0) // X < (small) --> false
3352 Result = ConstantBool::False;
3354 Result = ConstantBool::True; // X < (large) --> true
3356 // Unsigned extend and signed comparison.
3357 if (cast<ConstantSInt>(CI)->getValue() < 0)
3358 Result = ConstantBool::False;
3360 Result = ConstantBool::True;
3363 // We're performing an unsigned comparison.
3365 // Unsigned extend & compare -> always true.
3366 Result = ConstantBool::True;
3368 // We're performing an unsigned comp with a sign extended value.
3369 // This is true if the input is >= 0. [aka >s -1]
3370 Constant *NegOne = ConstantIntegral::getAllOnesValue(SrcTy);
3371 Result = InsertNewInstBefore(BinaryOperator::createSetGT(LHSCIOp,
3372 NegOne, SCI.getName()), SCI);
3376 // Finally, return the value computed.
3377 if (SCI.getOpcode() == Instruction::SetLT) {
3378 return ReplaceInstUsesWith(SCI, Result);
3380 assert(SCI.getOpcode()==Instruction::SetGT &&"SetCC should be folded!");
3381 if (Constant *CI = dyn_cast<Constant>(Result))
3382 return ReplaceInstUsesWith(SCI, ConstantExpr::getNot(CI));
3384 return BinaryOperator::createNot(Result);
3391 // Okay, just insert a compare of the reduced operands now!
3392 return BinaryOperator::create(SCI.getOpcode(), LHSCIOp, RHSCIOp);
3395 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
3396 assert(I.getOperand(1)->getType() == Type::UByteTy);
3397 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3398 bool isLeftShift = I.getOpcode() == Instruction::Shl;
3400 // shl X, 0 == X and shr X, 0 == X
3401 // shl 0, X == 0 and shr 0, X == 0
3402 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
3403 Op0 == Constant::getNullValue(Op0->getType()))
3404 return ReplaceInstUsesWith(I, Op0);
3406 if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
3407 if (!isLeftShift && I.getType()->isSigned())
3408 return ReplaceInstUsesWith(I, Op0);
3409 else // undef << X -> 0 AND undef >>u X -> 0
3410 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3412 if (isa<UndefValue>(Op1)) {
3413 if (isLeftShift || I.getType()->isUnsigned())// X << undef, X >>u undef -> 0
3414 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3416 return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X
3419 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
3421 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
3422 if (CSI->isAllOnesValue())
3423 return ReplaceInstUsesWith(I, CSI);
3425 // Try to fold constant and into select arguments.
3426 if (isa<Constant>(Op0))
3427 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
3428 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3431 // See if we can turn a signed shr into an unsigned shr.
3432 if (!isLeftShift && I.getType()->isSigned()) {
3433 if (MaskedValueIsZero(Op0, ConstantInt::getMinValue(I.getType()))) {
3434 Value *V = InsertCastBefore(Op0, I.getType()->getUnsignedVersion(), I);
3435 V = InsertNewInstBefore(new ShiftInst(Instruction::Shr, V, Op1,
3437 return new CastInst(V, I.getType());
3441 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
3442 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
3443 // of a signed value.
3445 unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits();
3446 if (CUI->getValue() >= TypeBits) {
3447 if (!Op0->getType()->isSigned() || isLeftShift)
3448 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
3450 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
3455 // ((X*C1) << C2) == (X * (C1 << C2))
3456 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
3457 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
3458 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
3459 return BinaryOperator::createMul(BO->getOperand(0),
3460 ConstantExpr::getShl(BOOp, CUI));
3462 // Try to fold constant and into select arguments.
3463 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3464 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3466 if (isa<PHINode>(Op0))
3467 if (Instruction *NV = FoldOpIntoPhi(I))
3470 if (Op0->hasOneUse()) {
3471 // If this is a SHL of a sign-extending cast, see if we can turn the input
3472 // into a zero extending cast (a simple strength reduction).
3473 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3474 const Type *SrcTy = CI->getOperand(0)->getType();
3475 if (isLeftShift && SrcTy->isInteger() && SrcTy->isSigned() &&
3476 SrcTy->getPrimitiveSizeInBits() <
3477 CI->getType()->getPrimitiveSizeInBits()) {
3478 // We can change it to a zero extension if we are shifting out all of
3479 // the sign extended bits. To check this, form a mask of all of the
3480 // sign extend bits, then shift them left and see if we have anything
3482 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); // 1111
3483 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); // 00001111
3484 Mask = ConstantExpr::getNot(Mask); // 1's in the sign bits: 11110000
3485 if (ConstantExpr::getShl(Mask, CUI)->isNullValue()) {
3486 // If the shift is nuking all of the sign bits, change this to a
3487 // zero extension cast. To do this, cast the cast input to
3488 // unsigned, then to the requested size.
3489 Value *CastOp = CI->getOperand(0);
3491 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
3492 CI->getName()+".uns");
3493 NC = InsertNewInstBefore(NC, I);
3494 // Finally, insert a replacement for CI.
3495 NC = new CastInst(NC, CI->getType(), CI->getName());
3497 NC = InsertNewInstBefore(NC, I);
3498 WorkList.push_back(CI); // Delete CI later.
3499 I.setOperand(0, NC);
3500 return &I; // The SHL operand was modified.
3505 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
3506 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
3509 switch (Op0BO->getOpcode()) {
3511 case Instruction::Add:
3512 case Instruction::And:
3513 case Instruction::Or:
3514 case Instruction::Xor:
3515 // These operators commute.
3516 // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
3517 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
3518 match(Op0BO->getOperand(1),
3519 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == CUI) {
3520 Instruction *YS = new ShiftInst(Instruction::Shl,
3521 Op0BO->getOperand(0), CUI,
3523 InsertNewInstBefore(YS, I); // (Y << C)
3524 Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
3526 Op0BO->getOperand(1)->getName());
3527 InsertNewInstBefore(X, I); // (X + (Y << C))
3528 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
3529 C2 = ConstantExpr::getShl(C2, CUI);
3530 return BinaryOperator::createAnd(X, C2);
3533 // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
3534 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
3535 match(Op0BO->getOperand(1),
3536 m_And(m_Shr(m_Value(V1), m_Value(V2)),
3537 m_ConstantInt(CC))) && V2 == CUI &&
3538 cast<BinaryOperator>(Op0BO->getOperand(1))->getOperand(0)->hasOneUse()) {
3539 Instruction *YS = new ShiftInst(Instruction::Shl,
3540 Op0BO->getOperand(0), CUI,
3542 InsertNewInstBefore(YS, I); // (Y << C)
3544 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, CUI),
3545 V1->getName()+".mask");
3546 InsertNewInstBefore(XM, I); // X & (CC << C)
3548 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
3552 case Instruction::Sub:
3553 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
3554 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
3555 match(Op0BO->getOperand(0),
3556 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == CUI) {
3557 Instruction *YS = new ShiftInst(Instruction::Shl,
3558 Op0BO->getOperand(1), CUI,
3560 InsertNewInstBefore(YS, I); // (Y << C)
3561 Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
3563 Op0BO->getOperand(0)->getName());
3564 InsertNewInstBefore(X, I); // (X + (Y << C))
3565 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
3566 C2 = ConstantExpr::getShl(C2, CUI);
3567 return BinaryOperator::createAnd(X, C2);
3570 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
3571 match(Op0BO->getOperand(0),
3572 m_And(m_Shr(m_Value(V1), m_Value(V2)),
3573 m_ConstantInt(CC))) && V2 == CUI &&
3574 cast<BinaryOperator>(Op0BO->getOperand(0))->getOperand(0)->hasOneUse()) {
3575 Instruction *YS = new ShiftInst(Instruction::Shl,
3576 Op0BO->getOperand(1), CUI,
3578 InsertNewInstBefore(YS, I); // (Y << C)
3580 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, CUI),
3581 V1->getName()+".mask");
3582 InsertNewInstBefore(XM, I); // X & (CC << C)
3584 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
3591 // If the operand is an bitwise operator with a constant RHS, and the
3592 // shift is the only use, we can pull it out of the shift.
3593 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
3594 bool isValid = true; // Valid only for And, Or, Xor
3595 bool highBitSet = false; // Transform if high bit of constant set?
3597 switch (Op0BO->getOpcode()) {
3598 default: isValid = false; break; // Do not perform transform!
3599 case Instruction::Add:
3600 isValid = isLeftShift;
3602 case Instruction::Or:
3603 case Instruction::Xor:
3606 case Instruction::And:
3611 // If this is a signed shift right, and the high bit is modified
3612 // by the logical operation, do not perform the transformation.
3613 // The highBitSet boolean indicates the value of the high bit of
3614 // the constant which would cause it to be modified for this
3617 if (isValid && !isLeftShift && !I.getType()->isUnsigned()) {
3618 uint64_t Val = Op0C->getRawValue();
3619 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
3623 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI);
3625 Instruction *NewShift =
3626 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI,
3629 InsertNewInstBefore(NewShift, I);
3631 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
3638 // If this is a shift of a shift, see if we can fold the two together...
3639 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
3640 if (ConstantUInt *ShiftAmt1C =
3641 dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) {
3642 unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getValue();
3643 unsigned ShiftAmt2 = (unsigned)CUI->getValue();
3645 // Check for (A << c1) << c2 and (A >> c1) >> c2
3646 if (I.getOpcode() == Op0SI->getOpcode()) {
3647 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
3648 if (Op0->getType()->getPrimitiveSizeInBits() < Amt)
3649 Amt = Op0->getType()->getPrimitiveSizeInBits();
3650 return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
3651 ConstantUInt::get(Type::UByteTy, Amt));
3654 // Check for (A << c1) >> c2 or visaversa. If we are dealing with
3655 // signed types, we can only support the (A >> c1) << c2 configuration,
3656 // because it can not turn an arbitrary bit of A into a sign bit.
3657 if (I.getType()->isUnsigned() || isLeftShift) {
3658 // Calculate bitmask for what gets shifted off the edge...
3659 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
3661 C = ConstantExpr::getShl(C, ShiftAmt1C);
3663 C = ConstantExpr::getShr(C, ShiftAmt1C);
3666 BinaryOperator::createAnd(Op0SI->getOperand(0), C,
3667 Op0SI->getOperand(0)->getName()+".mask");
3668 InsertNewInstBefore(Mask, I);
3670 // Figure out what flavor of shift we should use...
3671 if (ShiftAmt1 == ShiftAmt2)
3672 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
3673 else if (ShiftAmt1 < ShiftAmt2) {
3674 return new ShiftInst(I.getOpcode(), Mask,
3675 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
3677 return new ShiftInst(Op0SI->getOpcode(), Mask,
3678 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
3681 // We can handle signed (X << C1) >> C2 if it's a sign extend. In
3682 // this case, C1 == C2 and C1 is 8, 16, or 32.
3683 if (ShiftAmt1 == ShiftAmt2) {
3684 const Type *SExtType = 0;
3685 switch (ShiftAmt1) {
3686 case 8 : SExtType = Type::SByteTy; break;
3687 case 16: SExtType = Type::ShortTy; break;
3688 case 32: SExtType = Type::IntTy; break;
3692 Instruction *NewTrunc = new CastInst(Op0SI->getOperand(0),
3694 InsertNewInstBefore(NewTrunc, I);
3695 return new CastInst(NewTrunc, I.getType());
3712 /// getCastType - In the future, we will split the cast instruction into these
3713 /// various types. Until then, we have to do the analysis here.
3714 static CastType getCastType(const Type *Src, const Type *Dest) {
3715 assert(Src->isIntegral() && Dest->isIntegral() &&
3716 "Only works on integral types!");
3717 unsigned SrcSize = Src->getPrimitiveSizeInBits();
3718 unsigned DestSize = Dest->getPrimitiveSizeInBits();
3720 if (SrcSize == DestSize) return Noop;
3721 if (SrcSize > DestSize) return Truncate;
3722 if (Src->isSigned()) return Signext;
3727 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
3730 static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
3731 const Type *DstTy, TargetData *TD) {
3733 // It is legal to eliminate the instruction if casting A->B->A if the sizes
3734 // are identical and the bits don't get reinterpreted (for example
3735 // int->float->int would not be allowed).
3736 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
3739 // If we are casting between pointer and integer types, treat pointers as
3740 // integers of the appropriate size for the code below.
3741 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
3742 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
3743 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
3745 // Allow free casting and conversion of sizes as long as the sign doesn't
3747 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
3748 CastType FirstCast = getCastType(SrcTy, MidTy);
3749 CastType SecondCast = getCastType(MidTy, DstTy);
3751 // Capture the effect of these two casts. If the result is a legal cast,
3752 // the CastType is stored here, otherwise a special code is used.
3753 static const unsigned CastResult[] = {
3754 // First cast is noop
3756 // First cast is a truncate
3757 1, 1, 4, 4, // trunc->extend is not safe to eliminate
3758 // First cast is a sign ext
3759 2, 5, 2, 4, // signext->zeroext never ok
3760 // First cast is a zero ext
3764 unsigned Result = CastResult[FirstCast*4+SecondCast];
3766 default: assert(0 && "Illegal table value!");
3771 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
3772 // truncates, we could eliminate more casts.
3773 return (unsigned)getCastType(SrcTy, DstTy) == Result;
3775 return false; // Not possible to eliminate this here.
3777 // Sign or zero extend followed by truncate is always ok if the result
3778 // is a truncate or noop.
3779 CastType ResultCast = getCastType(SrcTy, DstTy);
3780 if (ResultCast == Noop || ResultCast == Truncate)
3782 // Otherwise we are still growing the value, we are only safe if the
3783 // result will match the sign/zeroextendness of the result.
3784 return ResultCast == FirstCast;
3790 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
3791 if (V->getType() == Ty || isa<Constant>(V)) return false;
3792 if (const CastInst *CI = dyn_cast<CastInst>(V))
3793 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
3799 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
3800 /// InsertBefore instruction. This is specialized a bit to avoid inserting
3801 /// casts that are known to not do anything...
3803 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
3804 Instruction *InsertBefore) {
3805 if (V->getType() == DestTy) return V;
3806 if (Constant *C = dyn_cast<Constant>(V))
3807 return ConstantExpr::getCast(C, DestTy);
3809 CastInst *CI = new CastInst(V, DestTy, V->getName());
3810 InsertNewInstBefore(CI, *InsertBefore);
3814 /// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
3815 /// expression. If so, decompose it, returning some value X, such that Val is
3818 static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
3820 assert(Val->getType() == Type::UIntTy && "Unexpected allocation size type!");
3821 if (ConstantUInt *CI = dyn_cast<ConstantUInt>(Val)) {
3822 Offset = CI->getValue();
3824 return ConstantUInt::get(Type::UIntTy, 0);
3825 } else if (Instruction *I = dyn_cast<Instruction>(Val)) {
3826 if (I->getNumOperands() == 2) {
3827 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(I->getOperand(1))) {
3828 if (I->getOpcode() == Instruction::Shl) {
3829 // This is a value scaled by '1 << the shift amt'.
3830 Scale = 1U << CUI->getValue();
3832 return I->getOperand(0);
3833 } else if (I->getOpcode() == Instruction::Mul) {
3834 // This value is scaled by 'CUI'.
3835 Scale = CUI->getValue();
3837 return I->getOperand(0);
3838 } else if (I->getOpcode() == Instruction::Add) {
3839 // We have X+C. Check to see if we really have (X*C2)+C1, where C1 is
3842 Value *SubVal = DecomposeSimpleLinearExpr(I->getOperand(0), SubScale,
3844 Offset += CUI->getValue();
3845 if (SubScale > 1 && (Offset % SubScale == 0)) {
3854 // Otherwise, we can't look past this.
3861 /// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
3862 /// try to eliminate the cast by moving the type information into the alloc.
3863 Instruction *InstCombiner::PromoteCastOfAllocation(CastInst &CI,
3864 AllocationInst &AI) {
3865 const PointerType *PTy = dyn_cast<PointerType>(CI.getType());
3866 if (!PTy) return 0; // Not casting the allocation to a pointer type.
3868 // Remove any uses of AI that are dead.
3869 assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
3870 std::vector<Instruction*> DeadUsers;
3871 for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
3872 Instruction *User = cast<Instruction>(*UI++);
3873 if (isInstructionTriviallyDead(User)) {
3874 while (UI != E && *UI == User)
3875 ++UI; // If this instruction uses AI more than once, don't break UI.
3877 // Add operands to the worklist.
3878 AddUsesToWorkList(*User);
3880 DEBUG(std::cerr << "IC: DCE: " << *User);
3882 User->eraseFromParent();
3883 removeFromWorkList(User);
3887 // Get the type really allocated and the type casted to.
3888 const Type *AllocElTy = AI.getAllocatedType();
3889 const Type *CastElTy = PTy->getElementType();
3890 if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
3892 unsigned AllocElTyAlign = TD->getTypeSize(AllocElTy);
3893 unsigned CastElTyAlign = TD->getTypeSize(CastElTy);
3894 if (CastElTyAlign < AllocElTyAlign) return 0;
3896 // If the allocation has multiple uses, only promote it if we are strictly
3897 // increasing the alignment of the resultant allocation. If we keep it the
3898 // same, we open the door to infinite loops of various kinds.
3899 if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return 0;
3901 uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
3902 uint64_t CastElTySize = TD->getTypeSize(CastElTy);
3903 if (CastElTySize == 0 || AllocElTySize == 0) return 0;
3905 // See if we can satisfy the modulus by pulling a scale out of the array
3907 unsigned ArraySizeScale, ArrayOffset;
3908 Value *NumElements = // See if the array size is a decomposable linear expr.
3909 DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
3911 // If we can now satisfy the modulus, by using a non-1 scale, we really can
3913 if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
3914 (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
3916 unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
3921 Amt = ConstantUInt::get(Type::UIntTy, Scale);
3922 if (ConstantUInt *CI = dyn_cast<ConstantUInt>(NumElements))
3923 Amt = ConstantExpr::getMul(CI, cast<ConstantUInt>(Amt));
3924 else if (Scale != 1) {
3925 Instruction *Tmp = BinaryOperator::createMul(Amt, NumElements, "tmp");
3926 Amt = InsertNewInstBefore(Tmp, AI);
3930 if (unsigned Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
3931 Value *Off = ConstantUInt::get(Type::UIntTy, Offset);
3932 Instruction *Tmp = BinaryOperator::createAdd(Amt, Off, "tmp");
3933 Amt = InsertNewInstBefore(Tmp, AI);
3936 std::string Name = AI.getName(); AI.setName("");
3937 AllocationInst *New;
3938 if (isa<MallocInst>(AI))
3939 New = new MallocInst(CastElTy, Amt, Name);
3941 New = new AllocaInst(CastElTy, Amt, Name);
3942 InsertNewInstBefore(New, AI);
3944 // If the allocation has multiple uses, insert a cast and change all things
3945 // that used it to use the new cast. This will also hack on CI, but it will
3947 if (!AI.hasOneUse()) {
3948 AddUsesToWorkList(AI);
3949 CastInst *NewCast = new CastInst(New, AI.getType(), "tmpcast");
3950 InsertNewInstBefore(NewCast, AI);
3951 AI.replaceAllUsesWith(NewCast);
3953 return ReplaceInstUsesWith(CI, New);
3957 // CastInst simplification
3959 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
3960 Value *Src = CI.getOperand(0);
3962 // If the user is casting a value to the same type, eliminate this cast
3964 if (CI.getType() == Src->getType())
3965 return ReplaceInstUsesWith(CI, Src);
3967 if (isa<UndefValue>(Src)) // cast undef -> undef
3968 return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
3970 // If casting the result of another cast instruction, try to eliminate this
3973 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
3974 Value *A = CSrc->getOperand(0);
3975 if (isEliminableCastOfCast(A->getType(), CSrc->getType(),
3976 CI.getType(), TD)) {
3977 // This instruction now refers directly to the cast's src operand. This
3978 // has a good chance of making CSrc dead.
3979 CI.setOperand(0, CSrc->getOperand(0));
3983 // If this is an A->B->A cast, and we are dealing with integral types, try
3984 // to convert this into a logical 'and' instruction.
3986 if (A->getType()->isInteger() &&
3987 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
3988 CSrc->getType()->isUnsigned() && // B->A cast must zero extend
3989 CSrc->getType()->getPrimitiveSizeInBits() <
3990 CI.getType()->getPrimitiveSizeInBits()&&
3991 A->getType()->getPrimitiveSizeInBits() ==
3992 CI.getType()->getPrimitiveSizeInBits()) {
3993 assert(CSrc->getType() != Type::ULongTy &&
3994 "Cannot have type bigger than ulong!");
3995 uint64_t AndValue = ~0ULL>>(64-CSrc->getType()->getPrimitiveSizeInBits());
3996 Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(),
3998 AndOp = ConstantExpr::getCast(AndOp, A->getType());
3999 Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
4000 if (And->getType() != CI.getType()) {
4001 And->setName(CSrc->getName()+".mask");
4002 InsertNewInstBefore(And, CI);
4003 And = new CastInst(And, CI.getType());
4009 // If this is a cast to bool, turn it into the appropriate setne instruction.
4010 if (CI.getType() == Type::BoolTy)
4011 return BinaryOperator::createSetNE(CI.getOperand(0),
4012 Constant::getNullValue(CI.getOperand(0)->getType()));
4014 // If casting the result of a getelementptr instruction with no offset, turn
4015 // this into a cast of the original pointer!
4017 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
4018 bool AllZeroOperands = true;
4019 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
4020 if (!isa<Constant>(GEP->getOperand(i)) ||
4021 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
4022 AllZeroOperands = false;
4025 if (AllZeroOperands) {
4026 CI.setOperand(0, GEP->getOperand(0));
4031 // If we are casting a malloc or alloca to a pointer to a type of the same
4032 // size, rewrite the allocation instruction to allocate the "right" type.
4034 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
4035 if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
4038 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
4039 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
4041 if (isa<PHINode>(Src))
4042 if (Instruction *NV = FoldOpIntoPhi(CI))
4045 // If the source value is an instruction with only this use, we can attempt to
4046 // propagate the cast into the instruction. Also, only handle integral types
4048 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
4049 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
4050 CI.getType()->isInteger()) { // Don't mess with casts to bool here
4051 const Type *DestTy = CI.getType();
4052 unsigned SrcBitSize = Src->getType()->getPrimitiveSizeInBits();
4053 unsigned DestBitSize = DestTy->getPrimitiveSizeInBits();
4055 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
4056 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
4058 switch (SrcI->getOpcode()) {
4059 case Instruction::Add:
4060 case Instruction::Mul:
4061 case Instruction::And:
4062 case Instruction::Or:
4063 case Instruction::Xor:
4064 // If we are discarding information, or just changing the sign, rewrite.
4065 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
4066 // Don't insert two casts if they cannot be eliminated. We allow two
4067 // casts to be inserted if the sizes are the same. This could only be
4068 // converting signedness, which is a noop.
4069 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
4070 !ValueRequiresCast(Op0, DestTy, TD)) {
4071 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
4072 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
4073 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
4074 ->getOpcode(), Op0c, Op1c);
4078 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
4079 if (SrcBitSize == 1 && SrcI->getOpcode() == Instruction::Xor &&
4080 Op1 == ConstantBool::True &&
4081 (!Op0->hasOneUse() || !isa<SetCondInst>(Op0))) {
4082 Value *New = InsertOperandCastBefore(Op0, DestTy, &CI);
4083 return BinaryOperator::createXor(New,
4084 ConstantInt::get(CI.getType(), 1));
4087 case Instruction::Shl:
4088 // Allow changing the sign of the source operand. Do not allow changing
4089 // the size of the shift, UNLESS the shift amount is a constant. We
4090 // mush not change variable sized shifts to a smaller size, because it
4091 // is undefined to shift more bits out than exist in the value.
4092 if (DestBitSize == SrcBitSize ||
4093 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
4094 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
4095 return new ShiftInst(Instruction::Shl, Op0c, Op1);
4098 case Instruction::Shr:
4099 // If this is a signed shr, and if all bits shifted in are about to be
4100 // truncated off, turn it into an unsigned shr to allow greater
4102 if (DestBitSize < SrcBitSize && Src->getType()->isSigned() &&
4103 isa<ConstantInt>(Op1)) {
4104 unsigned ShiftAmt = cast<ConstantUInt>(Op1)->getValue();
4105 if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
4106 // Convert to unsigned.
4107 Value *N1 = InsertOperandCastBefore(Op0,
4108 Op0->getType()->getUnsignedVersion(), &CI);
4109 // Insert the new shift, which is now unsigned.
4110 N1 = InsertNewInstBefore(new ShiftInst(Instruction::Shr, N1,
4111 Op1, Src->getName()), CI);
4112 return new CastInst(N1, CI.getType());
4117 case Instruction::SetNE:
4118 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
4119 if (Op1C->getRawValue() == 0) {
4120 // If the input only has the low bit set, simplify directly.
4122 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
4123 // cast (X != 0) to int --> X if X&~1 == 0
4124 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
4125 if (CI.getType() == Op0->getType())
4126 return ReplaceInstUsesWith(CI, Op0);
4128 return new CastInst(Op0, CI.getType());
4131 // If the input is an and with a single bit, shift then simplify.
4132 ConstantInt *AndRHS;
4133 if (match(Op0, m_And(m_Value(), m_ConstantInt(AndRHS))))
4134 if (AndRHS->getRawValue() &&
4135 (AndRHS->getRawValue() & (AndRHS->getRawValue()-1)) == 0) {
4136 unsigned ShiftAmt = Log2_64(AndRHS->getRawValue());
4137 // Perform an unsigned shr by shiftamt. Convert input to
4138 // unsigned if it is signed.
4140 if (In->getType()->isSigned())
4141 In = InsertNewInstBefore(new CastInst(In,
4142 In->getType()->getUnsignedVersion(), In->getName()),CI);
4143 // Insert the shift to put the result in the low bit.
4144 In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In,
4145 ConstantInt::get(Type::UByteTy, ShiftAmt),
4146 In->getName()+".lobit"), CI);
4147 if (CI.getType() == In->getType())
4148 return ReplaceInstUsesWith(CI, In);
4150 return new CastInst(In, CI.getType());
4155 case Instruction::SetEQ:
4156 // We if we are just checking for a seteq of a single bit and casting it
4157 // to an integer. If so, shift the bit to the appropriate place then
4158 // cast to integer to avoid the comparison.
4159 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
4160 // Is Op1C a power of two or zero?
4161 if ((Op1C->getRawValue() & Op1C->getRawValue()-1) == 0) {
4162 // cast (X == 1) to int -> X iff X has only the low bit set.
4163 if (Op1C->getRawValue() == 1) {
4165 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
4166 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
4167 if (CI.getType() == Op0->getType())
4168 return ReplaceInstUsesWith(CI, Op0);
4170 return new CastInst(Op0, CI.getType());
4182 /// GetSelectFoldableOperands - We want to turn code that looks like this:
4184 /// %D = select %cond, %C, %A
4186 /// %C = select %cond, %B, 0
4189 /// Assuming that the specified instruction is an operand to the select, return
4190 /// a bitmask indicating which operands of this instruction are foldable if they
4191 /// equal the other incoming value of the select.
4193 static unsigned GetSelectFoldableOperands(Instruction *I) {
4194 switch (I->getOpcode()) {
4195 case Instruction::Add:
4196 case Instruction::Mul:
4197 case Instruction::And:
4198 case Instruction::Or:
4199 case Instruction::Xor:
4200 return 3; // Can fold through either operand.
4201 case Instruction::Sub: // Can only fold on the amount subtracted.
4202 case Instruction::Shl: // Can only fold on the shift amount.
4203 case Instruction::Shr:
4206 return 0; // Cannot fold
4210 /// GetSelectFoldableConstant - For the same transformation as the previous
4211 /// function, return the identity constant that goes into the select.
4212 static Constant *GetSelectFoldableConstant(Instruction *I) {
4213 switch (I->getOpcode()) {
4214 default: assert(0 && "This cannot happen!"); abort();
4215 case Instruction::Add:
4216 case Instruction::Sub:
4217 case Instruction::Or:
4218 case Instruction::Xor:
4219 return Constant::getNullValue(I->getType());
4220 case Instruction::Shl:
4221 case Instruction::Shr:
4222 return Constant::getNullValue(Type::UByteTy);
4223 case Instruction::And:
4224 return ConstantInt::getAllOnesValue(I->getType());
4225 case Instruction::Mul:
4226 return ConstantInt::get(I->getType(), 1);
4230 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
4231 /// have the same opcode and only one use each. Try to simplify this.
4232 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
4234 if (TI->getNumOperands() == 1) {
4235 // If this is a non-volatile load or a cast from the same type,
4237 if (TI->getOpcode() == Instruction::Cast) {
4238 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
4241 return 0; // unknown unary op.
4244 // Fold this by inserting a select from the input values.
4245 SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
4246 FI->getOperand(0), SI.getName()+".v");
4247 InsertNewInstBefore(NewSI, SI);
4248 return new CastInst(NewSI, TI->getType());
4251 // Only handle binary operators here.
4252 if (!isa<ShiftInst>(TI) && !isa<BinaryOperator>(TI))
4255 // Figure out if the operations have any operands in common.
4256 Value *MatchOp, *OtherOpT, *OtherOpF;
4258 if (TI->getOperand(0) == FI->getOperand(0)) {
4259 MatchOp = TI->getOperand(0);
4260 OtherOpT = TI->getOperand(1);
4261 OtherOpF = FI->getOperand(1);
4262 MatchIsOpZero = true;
4263 } else if (TI->getOperand(1) == FI->getOperand(1)) {
4264 MatchOp = TI->getOperand(1);
4265 OtherOpT = TI->getOperand(0);
4266 OtherOpF = FI->getOperand(0);
4267 MatchIsOpZero = false;
4268 } else if (!TI->isCommutative()) {
4270 } else if (TI->getOperand(0) == FI->getOperand(1)) {
4271 MatchOp = TI->getOperand(0);
4272 OtherOpT = TI->getOperand(1);
4273 OtherOpF = FI->getOperand(0);
4274 MatchIsOpZero = true;
4275 } else if (TI->getOperand(1) == FI->getOperand(0)) {
4276 MatchOp = TI->getOperand(1);
4277 OtherOpT = TI->getOperand(0);
4278 OtherOpF = FI->getOperand(1);
4279 MatchIsOpZero = true;
4284 // If we reach here, they do have operations in common.
4285 SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
4286 OtherOpF, SI.getName()+".v");
4287 InsertNewInstBefore(NewSI, SI);
4289 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
4291 return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
4293 return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
4296 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI);
4298 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp);
4302 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
4303 Value *CondVal = SI.getCondition();
4304 Value *TrueVal = SI.getTrueValue();
4305 Value *FalseVal = SI.getFalseValue();
4307 // select true, X, Y -> X
4308 // select false, X, Y -> Y
4309 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
4310 if (C == ConstantBool::True)
4311 return ReplaceInstUsesWith(SI, TrueVal);
4313 assert(C == ConstantBool::False);
4314 return ReplaceInstUsesWith(SI, FalseVal);
4317 // select C, X, X -> X
4318 if (TrueVal == FalseVal)
4319 return ReplaceInstUsesWith(SI, TrueVal);
4321 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
4322 return ReplaceInstUsesWith(SI, FalseVal);
4323 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
4324 return ReplaceInstUsesWith(SI, TrueVal);
4325 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
4326 if (isa<Constant>(TrueVal))
4327 return ReplaceInstUsesWith(SI, TrueVal);
4329 return ReplaceInstUsesWith(SI, FalseVal);
4332 if (SI.getType() == Type::BoolTy)
4333 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
4334 if (C == ConstantBool::True) {
4335 // Change: A = select B, true, C --> A = or B, C
4336 return BinaryOperator::createOr(CondVal, FalseVal);
4338 // Change: A = select B, false, C --> A = and !B, C
4340 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4341 "not."+CondVal->getName()), SI);
4342 return BinaryOperator::createAnd(NotCond, FalseVal);
4344 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
4345 if (C == ConstantBool::False) {
4346 // Change: A = select B, C, false --> A = and B, C
4347 return BinaryOperator::createAnd(CondVal, TrueVal);
4349 // Change: A = select B, C, true --> A = or !B, C
4351 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4352 "not."+CondVal->getName()), SI);
4353 return BinaryOperator::createOr(NotCond, TrueVal);
4357 // Selecting between two integer constants?
4358 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
4359 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
4360 // select C, 1, 0 -> cast C to int
4361 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
4362 return new CastInst(CondVal, SI.getType());
4363 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
4364 // select C, 0, 1 -> cast !C to int
4366 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4367 "not."+CondVal->getName()), SI);
4368 return new CastInst(NotCond, SI.getType());
4371 // If one of the constants is zero (we know they can't both be) and we
4372 // have a setcc instruction with zero, and we have an 'and' with the
4373 // non-constant value, eliminate this whole mess. This corresponds to
4374 // cases like this: ((X & 27) ? 27 : 0)
4375 if (TrueValC->isNullValue() || FalseValC->isNullValue())
4376 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
4377 if ((IC->getOpcode() == Instruction::SetEQ ||
4378 IC->getOpcode() == Instruction::SetNE) &&
4379 isa<ConstantInt>(IC->getOperand(1)) &&
4380 cast<Constant>(IC->getOperand(1))->isNullValue())
4381 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
4382 if (ICA->getOpcode() == Instruction::And &&
4383 isa<ConstantInt>(ICA->getOperand(1)) &&
4384 (ICA->getOperand(1) == TrueValC ||
4385 ICA->getOperand(1) == FalseValC) &&
4386 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
4387 // Okay, now we know that everything is set up, we just don't
4388 // know whether we have a setne or seteq and whether the true or
4389 // false val is the zero.
4390 bool ShouldNotVal = !TrueValC->isNullValue();
4391 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
4394 V = InsertNewInstBefore(BinaryOperator::create(
4395 Instruction::Xor, V, ICA->getOperand(1)), SI);
4396 return ReplaceInstUsesWith(SI, V);
4400 // See if we are selecting two values based on a comparison of the two values.
4401 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
4402 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
4403 // Transform (X == Y) ? X : Y -> Y
4404 if (SCI->getOpcode() == Instruction::SetEQ)
4405 return ReplaceInstUsesWith(SI, FalseVal);
4406 // Transform (X != Y) ? X : Y -> X
4407 if (SCI->getOpcode() == Instruction::SetNE)
4408 return ReplaceInstUsesWith(SI, TrueVal);
4409 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
4411 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
4412 // Transform (X == Y) ? Y : X -> X
4413 if (SCI->getOpcode() == Instruction::SetEQ)
4414 return ReplaceInstUsesWith(SI, FalseVal);
4415 // Transform (X != Y) ? Y : X -> Y
4416 if (SCI->getOpcode() == Instruction::SetNE)
4417 return ReplaceInstUsesWith(SI, TrueVal);
4418 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
4422 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
4423 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
4424 if (TI->hasOneUse() && FI->hasOneUse()) {
4425 bool isInverse = false;
4426 Instruction *AddOp = 0, *SubOp = 0;
4428 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
4429 if (TI->getOpcode() == FI->getOpcode())
4430 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
4433 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
4434 // even legal for FP.
4435 if (TI->getOpcode() == Instruction::Sub &&
4436 FI->getOpcode() == Instruction::Add) {
4437 AddOp = FI; SubOp = TI;
4438 } else if (FI->getOpcode() == Instruction::Sub &&
4439 TI->getOpcode() == Instruction::Add) {
4440 AddOp = TI; SubOp = FI;
4444 Value *OtherAddOp = 0;
4445 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
4446 OtherAddOp = AddOp->getOperand(1);
4447 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
4448 OtherAddOp = AddOp->getOperand(0);
4452 // So at this point we know we have:
4453 // select C, (add X, Y), (sub X, ?)
4454 // We can do the transform profitably if either 'Y' = '?' or '?' is
4456 if (SubOp->getOperand(1) == AddOp ||
4457 isa<Constant>(SubOp->getOperand(1))) {
4459 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
4460 NegVal = ConstantExpr::getNeg(C);
4462 NegVal = InsertNewInstBefore(
4463 BinaryOperator::createNeg(SubOp->getOperand(1)), SI);
4466 Value *NewTrueOp = OtherAddOp;
4467 Value *NewFalseOp = NegVal;
4469 std::swap(NewTrueOp, NewFalseOp);
4470 Instruction *NewSel =
4471 new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
4473 NewSel = InsertNewInstBefore(NewSel, SI);
4474 return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
4480 // See if we can fold the select into one of our operands.
4481 if (SI.getType()->isInteger()) {
4482 // See the comment above GetSelectFoldableOperands for a description of the
4483 // transformation we are doing here.
4484 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
4485 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
4486 !isa<Constant>(FalseVal))
4487 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
4488 unsigned OpToFold = 0;
4489 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
4491 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
4496 Constant *C = GetSelectFoldableConstant(TVI);
4497 std::string Name = TVI->getName(); TVI->setName("");
4498 Instruction *NewSel =
4499 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
4501 InsertNewInstBefore(NewSel, SI);
4502 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
4503 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
4504 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
4505 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
4507 assert(0 && "Unknown instruction!!");
4512 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
4513 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
4514 !isa<Constant>(TrueVal))
4515 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
4516 unsigned OpToFold = 0;
4517 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
4519 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
4524 Constant *C = GetSelectFoldableConstant(FVI);
4525 std::string Name = FVI->getName(); FVI->setName("");
4526 Instruction *NewSel =
4527 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
4529 InsertNewInstBefore(NewSel, SI);
4530 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
4531 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
4532 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
4533 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
4535 assert(0 && "Unknown instruction!!");
4541 if (BinaryOperator::isNot(CondVal)) {
4542 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
4543 SI.setOperand(1, FalseVal);
4544 SI.setOperand(2, TrueVal);
4552 // CallInst simplification
4554 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
4555 // Intrinsics cannot occur in an invoke, so handle them here instead of in
4557 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(&CI)) {
4558 bool Changed = false;
4560 // memmove/cpy/set of zero bytes is a noop.
4561 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
4562 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
4564 // FIXME: Increase alignment here.
4566 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
4567 if (CI->getRawValue() == 1) {
4568 // Replace the instruction with just byte operations. We would
4569 // transform other cases to loads/stores, but we don't know if
4570 // alignment is sufficient.
4574 // If we have a memmove and the source operation is a constant global,
4575 // then the source and dest pointers can't alias, so we can change this
4576 // into a call to memcpy.
4577 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI))
4578 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
4579 if (GVSrc->isConstant()) {
4580 Module *M = CI.getParent()->getParent()->getParent();
4581 Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
4582 CI.getCalledFunction()->getFunctionType());
4583 CI.setOperand(0, MemCpy);
4587 if (Changed) return &CI;
4588 } else if (DbgStopPointInst *SPI = dyn_cast<DbgStopPointInst>(&CI)) {
4589 // If this stoppoint is at the same source location as the previous
4590 // stoppoint in the chain, it is not needed.
4591 if (DbgStopPointInst *PrevSPI =
4592 dyn_cast<DbgStopPointInst>(SPI->getChain()))
4593 if (SPI->getLineNo() == PrevSPI->getLineNo() &&
4594 SPI->getColNo() == PrevSPI->getColNo()) {
4595 SPI->replaceAllUsesWith(PrevSPI);
4596 return EraseInstFromFunction(CI);
4600 return visitCallSite(&CI);
4603 // InvokeInst simplification
4605 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
4606 return visitCallSite(&II);
4609 // visitCallSite - Improvements for call and invoke instructions.
4611 Instruction *InstCombiner::visitCallSite(CallSite CS) {
4612 bool Changed = false;
4614 // If the callee is a constexpr cast of a function, attempt to move the cast
4615 // to the arguments of the call/invoke.
4616 if (transformConstExprCastCall(CS)) return 0;
4618 Value *Callee = CS.getCalledValue();
4620 if (Function *CalleeF = dyn_cast<Function>(Callee))
4621 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
4622 Instruction *OldCall = CS.getInstruction();
4623 // If the call and callee calling conventions don't match, this call must
4624 // be unreachable, as the call is undefined.
4625 new StoreInst(ConstantBool::True,
4626 UndefValue::get(PointerType::get(Type::BoolTy)), OldCall);
4627 if (!OldCall->use_empty())
4628 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
4629 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
4630 return EraseInstFromFunction(*OldCall);
4634 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
4635 // This instruction is not reachable, just remove it. We insert a store to
4636 // undef so that we know that this code is not reachable, despite the fact
4637 // that we can't modify the CFG here.
4638 new StoreInst(ConstantBool::True,
4639 UndefValue::get(PointerType::get(Type::BoolTy)),
4640 CS.getInstruction());
4642 if (!CS.getInstruction()->use_empty())
4643 CS.getInstruction()->
4644 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
4646 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
4647 // Don't break the CFG, insert a dummy cond branch.
4648 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
4649 ConstantBool::True, II);
4651 return EraseInstFromFunction(*CS.getInstruction());
4654 const PointerType *PTy = cast<PointerType>(Callee->getType());
4655 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
4656 if (FTy->isVarArg()) {
4657 // See if we can optimize any arguments passed through the varargs area of
4659 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
4660 E = CS.arg_end(); I != E; ++I)
4661 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
4662 // If this cast does not effect the value passed through the varargs
4663 // area, we can eliminate the use of the cast.
4664 Value *Op = CI->getOperand(0);
4665 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
4672 return Changed ? CS.getInstruction() : 0;
4675 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
4676 // attempt to move the cast to the arguments of the call/invoke.
4678 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
4679 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
4680 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
4681 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
4683 Function *Callee = cast<Function>(CE->getOperand(0));
4684 Instruction *Caller = CS.getInstruction();
4686 // Okay, this is a cast from a function to a different type. Unless doing so
4687 // would cause a type conversion of one of our arguments, change this call to
4688 // be a direct call with arguments casted to the appropriate types.
4690 const FunctionType *FT = Callee->getFunctionType();
4691 const Type *OldRetTy = Caller->getType();
4693 // Check to see if we are changing the return type...
4694 if (OldRetTy != FT->getReturnType()) {
4695 if (Callee->isExternal() &&
4696 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
4697 !Caller->use_empty())
4698 return false; // Cannot transform this return value...
4700 // If the callsite is an invoke instruction, and the return value is used by
4701 // a PHI node in a successor, we cannot change the return type of the call
4702 // because there is no place to put the cast instruction (without breaking
4703 // the critical edge). Bail out in this case.
4704 if (!Caller->use_empty())
4705 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
4706 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
4708 if (PHINode *PN = dyn_cast<PHINode>(*UI))
4709 if (PN->getParent() == II->getNormalDest() ||
4710 PN->getParent() == II->getUnwindDest())
4714 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
4715 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
4717 CallSite::arg_iterator AI = CS.arg_begin();
4718 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
4719 const Type *ParamTy = FT->getParamType(i);
4720 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
4721 if (Callee->isExternal() && !isConvertible) return false;
4724 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
4725 Callee->isExternal())
4726 return false; // Do not delete arguments unless we have a function body...
4728 // Okay, we decided that this is a safe thing to do: go ahead and start
4729 // inserting cast instructions as necessary...
4730 std::vector<Value*> Args;
4731 Args.reserve(NumActualArgs);
4733 AI = CS.arg_begin();
4734 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
4735 const Type *ParamTy = FT->getParamType(i);
4736 if ((*AI)->getType() == ParamTy) {
4737 Args.push_back(*AI);
4739 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
4744 // If the function takes more arguments than the call was taking, add them
4746 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
4747 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
4749 // If we are removing arguments to the function, emit an obnoxious warning...
4750 if (FT->getNumParams() < NumActualArgs)
4751 if (!FT->isVarArg()) {
4752 std::cerr << "WARNING: While resolving call to function '"
4753 << Callee->getName() << "' arguments were dropped!\n";
4755 // Add all of the arguments in their promoted form to the arg list...
4756 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
4757 const Type *PTy = getPromotedType((*AI)->getType());
4758 if (PTy != (*AI)->getType()) {
4759 // Must promote to pass through va_arg area!
4760 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
4761 InsertNewInstBefore(Cast, *Caller);
4762 Args.push_back(Cast);
4764 Args.push_back(*AI);
4769 if (FT->getReturnType() == Type::VoidTy)
4770 Caller->setName(""); // Void type should not have a name...
4773 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4774 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
4775 Args, Caller->getName(), Caller);
4776 cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
4778 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
4779 if (cast<CallInst>(Caller)->isTailCall())
4780 cast<CallInst>(NC)->setTailCall();
4781 cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
4784 // Insert a cast of the return type as necessary...
4786 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
4787 if (NV->getType() != Type::VoidTy) {
4788 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
4790 // If this is an invoke instruction, we should insert it after the first
4791 // non-phi, instruction in the normal successor block.
4792 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4793 BasicBlock::iterator I = II->getNormalDest()->begin();
4794 while (isa<PHINode>(I)) ++I;
4795 InsertNewInstBefore(NC, *I);
4797 // Otherwise, it's a call, just insert cast right after the call instr
4798 InsertNewInstBefore(NC, *Caller);
4800 AddUsersToWorkList(*Caller);
4802 NV = UndefValue::get(Caller->getType());
4806 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
4807 Caller->replaceAllUsesWith(NV);
4808 Caller->getParent()->getInstList().erase(Caller);
4809 removeFromWorkList(Caller);
4814 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
4815 // operator and they all are only used by the PHI, PHI together their
4816 // inputs, and do the operation once, to the result of the PHI.
4817 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
4818 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
4820 // Scan the instruction, looking for input operations that can be folded away.
4821 // If all input operands to the phi are the same instruction (e.g. a cast from
4822 // the same type or "+42") we can pull the operation through the PHI, reducing
4823 // code size and simplifying code.
4824 Constant *ConstantOp = 0;
4825 const Type *CastSrcTy = 0;
4826 if (isa<CastInst>(FirstInst)) {
4827 CastSrcTy = FirstInst->getOperand(0)->getType();
4828 } else if (isa<BinaryOperator>(FirstInst) || isa<ShiftInst>(FirstInst)) {
4829 // Can fold binop or shift if the RHS is a constant.
4830 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
4831 if (ConstantOp == 0) return 0;
4833 return 0; // Cannot fold this operation.
4836 // Check to see if all arguments are the same operation.
4837 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4838 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
4839 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
4840 if (!I->hasOneUse() || I->getOpcode() != FirstInst->getOpcode())
4843 if (I->getOperand(0)->getType() != CastSrcTy)
4844 return 0; // Cast operation must match.
4845 } else if (I->getOperand(1) != ConstantOp) {
4850 // Okay, they are all the same operation. Create a new PHI node of the
4851 // correct type, and PHI together all of the LHS's of the instructions.
4852 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
4853 PN.getName()+".in");
4854 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
4856 Value *InVal = FirstInst->getOperand(0);
4857 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
4859 // Add all operands to the new PHI.
4860 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4861 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
4862 if (NewInVal != InVal)
4864 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
4869 // The new PHI unions all of the same values together. This is really
4870 // common, so we handle it intelligently here for compile-time speed.
4874 InsertNewInstBefore(NewPN, PN);
4878 // Insert and return the new operation.
4879 if (isa<CastInst>(FirstInst))
4880 return new CastInst(PhiVal, PN.getType());
4881 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
4882 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
4884 return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(),
4885 PhiVal, ConstantOp);
4888 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
4890 static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &PotentiallyDeadPHIs) {
4891 if (PN->use_empty()) return true;
4892 if (!PN->hasOneUse()) return false;
4894 // Remember this node, and if we find the cycle, return.
4895 if (!PotentiallyDeadPHIs.insert(PN).second)
4898 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
4899 return DeadPHICycle(PU, PotentiallyDeadPHIs);
4904 // PHINode simplification
4906 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
4907 if (Value *V = PN.hasConstantValue())
4908 return ReplaceInstUsesWith(PN, V);
4910 // If the only user of this instruction is a cast instruction, and all of the
4911 // incoming values are constants, change this PHI to merge together the casted
4914 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
4915 if (CI->getType() != PN.getType()) { // noop casts will be folded
4916 bool AllConstant = true;
4917 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
4918 if (!isa<Constant>(PN.getIncomingValue(i))) {
4919 AllConstant = false;
4923 // Make a new PHI with all casted values.
4924 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
4925 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
4926 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
4927 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
4928 PN.getIncomingBlock(i));
4931 // Update the cast instruction.
4932 CI->setOperand(0, New);
4933 WorkList.push_back(CI); // revisit the cast instruction to fold.
4934 WorkList.push_back(New); // Make sure to revisit the new Phi
4935 return &PN; // PN is now dead!
4939 // If all PHI operands are the same operation, pull them through the PHI,
4940 // reducing code size.
4941 if (isa<Instruction>(PN.getIncomingValue(0)) &&
4942 PN.getIncomingValue(0)->hasOneUse())
4943 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
4946 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
4947 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
4948 // PHI)... break the cycle.
4950 if (PHINode *PU = dyn_cast<PHINode>(PN.use_back())) {
4951 std::set<PHINode*> PotentiallyDeadPHIs;
4952 PotentiallyDeadPHIs.insert(&PN);
4953 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
4954 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
4960 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
4961 Instruction *InsertPoint,
4963 unsigned PS = IC->getTargetData().getPointerSize();
4964 const Type *VTy = V->getType();
4965 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
4966 // We must insert a cast to ensure we sign-extend.
4967 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
4968 V->getName()), *InsertPoint);
4969 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
4974 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
4975 Value *PtrOp = GEP.getOperand(0);
4976 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
4977 // If so, eliminate the noop.
4978 if (GEP.getNumOperands() == 1)
4979 return ReplaceInstUsesWith(GEP, PtrOp);
4981 if (isa<UndefValue>(GEP.getOperand(0)))
4982 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
4984 bool HasZeroPointerIndex = false;
4985 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
4986 HasZeroPointerIndex = C->isNullValue();
4988 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
4989 return ReplaceInstUsesWith(GEP, PtrOp);
4991 // Eliminate unneeded casts for indices.
4992 bool MadeChange = false;
4993 gep_type_iterator GTI = gep_type_begin(GEP);
4994 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
4995 if (isa<SequentialType>(*GTI)) {
4996 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
4997 Value *Src = CI->getOperand(0);
4998 const Type *SrcTy = Src->getType();
4999 const Type *DestTy = CI->getType();
5000 if (Src->getType()->isInteger()) {
5001 if (SrcTy->getPrimitiveSizeInBits() ==
5002 DestTy->getPrimitiveSizeInBits()) {
5003 // We can always eliminate a cast from ulong or long to the other.
5004 // We can always eliminate a cast from uint to int or the other on
5005 // 32-bit pointer platforms.
5006 if (DestTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()){
5008 GEP.setOperand(i, Src);
5010 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
5011 SrcTy->getPrimitiveSize() == 4) {
5012 // We can always eliminate a cast from int to [u]long. We can
5013 // eliminate a cast from uint to [u]long iff the target is a 32-bit
5015 if (SrcTy->isSigned() ||
5016 SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
5018 GEP.setOperand(i, Src);
5023 // If we are using a wider index than needed for this platform, shrink it
5024 // to what we need. If the incoming value needs a cast instruction,
5025 // insert it. This explicit cast can make subsequent optimizations more
5027 Value *Op = GEP.getOperand(i);
5028 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
5029 if (Constant *C = dyn_cast<Constant>(Op)) {
5030 GEP.setOperand(i, ConstantExpr::getCast(C,
5031 TD->getIntPtrType()->getSignedVersion()));
5034 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
5035 Op->getName()), GEP);
5036 GEP.setOperand(i, Op);
5040 // If this is a constant idx, make sure to canonicalize it to be a signed
5041 // operand, otherwise CSE and other optimizations are pessimized.
5042 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
5043 GEP.setOperand(i, ConstantExpr::getCast(CUI,
5044 CUI->getType()->getSignedVersion()));
5048 if (MadeChange) return &GEP;
5050 // Combine Indices - If the source pointer to this getelementptr instruction
5051 // is a getelementptr instruction, combine the indices of the two
5052 // getelementptr instructions into a single instruction.
5054 std::vector<Value*> SrcGEPOperands;
5055 if (User *Src = dyn_castGetElementPtr(PtrOp))
5056 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
5058 if (!SrcGEPOperands.empty()) {
5059 // Note that if our source is a gep chain itself that we wait for that
5060 // chain to be resolved before we perform this transformation. This
5061 // avoids us creating a TON of code in some cases.
5063 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
5064 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
5065 return 0; // Wait until our source is folded to completion.
5067 std::vector<Value *> Indices;
5069 // Find out whether the last index in the source GEP is a sequential idx.
5070 bool EndsWithSequential = false;
5071 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
5072 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
5073 EndsWithSequential = !isa<StructType>(*I);
5075 // Can we combine the two pointer arithmetics offsets?
5076 if (EndsWithSequential) {
5077 // Replace: gep (gep %P, long B), long A, ...
5078 // With: T = long A+B; gep %P, T, ...
5080 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
5081 if (SO1 == Constant::getNullValue(SO1->getType())) {
5083 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
5086 // If they aren't the same type, convert both to an integer of the
5087 // target's pointer size.
5088 if (SO1->getType() != GO1->getType()) {
5089 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
5090 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
5091 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
5092 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
5094 unsigned PS = TD->getPointerSize();
5095 if (SO1->getType()->getPrimitiveSize() == PS) {
5096 // Convert GO1 to SO1's type.
5097 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
5099 } else if (GO1->getType()->getPrimitiveSize() == PS) {
5100 // Convert SO1 to GO1's type.
5101 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
5103 const Type *PT = TD->getIntPtrType();
5104 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
5105 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
5109 if (isa<Constant>(SO1) && isa<Constant>(GO1))
5110 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
5112 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
5113 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
5117 // Recycle the GEP we already have if possible.
5118 if (SrcGEPOperands.size() == 2) {
5119 GEP.setOperand(0, SrcGEPOperands[0]);
5120 GEP.setOperand(1, Sum);
5123 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
5124 SrcGEPOperands.end()-1);
5125 Indices.push_back(Sum);
5126 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
5128 } else if (isa<Constant>(*GEP.idx_begin()) &&
5129 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
5130 SrcGEPOperands.size() != 1) {
5131 // Otherwise we can do the fold if the first index of the GEP is a zero
5132 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
5133 SrcGEPOperands.end());
5134 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
5137 if (!Indices.empty())
5138 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
5140 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
5141 // GEP of global variable. If all of the indices for this GEP are
5142 // constants, we can promote this to a constexpr instead of an instruction.
5144 // Scan for nonconstants...
5145 std::vector<Constant*> Indices;
5146 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
5147 for (; I != E && isa<Constant>(*I); ++I)
5148 Indices.push_back(cast<Constant>(*I));
5150 if (I == E) { // If they are all constants...
5151 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
5153 // Replace all uses of the GEP with the new constexpr...
5154 return ReplaceInstUsesWith(GEP, CE);
5156 } else if (Value *X = isCast(PtrOp)) { // Is the operand a cast?
5157 if (!isa<PointerType>(X->getType())) {
5158 // Not interesting. Source pointer must be a cast from pointer.
5159 } else if (HasZeroPointerIndex) {
5160 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
5161 // into : GEP [10 x ubyte]* X, long 0, ...
5163 // This occurs when the program declares an array extern like "int X[];"
5165 const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
5166 const PointerType *XTy = cast<PointerType>(X->getType());
5167 if (const ArrayType *XATy =
5168 dyn_cast<ArrayType>(XTy->getElementType()))
5169 if (const ArrayType *CATy =
5170 dyn_cast<ArrayType>(CPTy->getElementType()))
5171 if (CATy->getElementType() == XATy->getElementType()) {
5172 // At this point, we know that the cast source type is a pointer
5173 // to an array of the same type as the destination pointer
5174 // array. Because the array type is never stepped over (there
5175 // is a leading zero) we can fold the cast into this GEP.
5176 GEP.setOperand(0, X);
5179 } else if (GEP.getNumOperands() == 2) {
5180 // Transform things like:
5181 // %t = getelementptr ubyte* cast ([2 x int]* %str to uint*), uint %V
5182 // into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast
5183 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
5184 const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
5185 if (isa<ArrayType>(SrcElTy) &&
5186 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
5187 TD->getTypeSize(ResElTy)) {
5188 Value *V = InsertNewInstBefore(
5189 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
5190 GEP.getOperand(1), GEP.getName()), GEP);
5191 return new CastInst(V, GEP.getType());
5194 // Transform things like:
5195 // getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp
5196 // (where tmp = 8*tmp2) into:
5197 // getelementptr [100 x double]* %arr, int 0, int %tmp.2
5199 if (isa<ArrayType>(SrcElTy) &&
5200 (ResElTy == Type::SByteTy || ResElTy == Type::UByteTy)) {
5201 uint64_t ArrayEltSize =
5202 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType());
5204 // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
5205 // allow either a mul, shift, or constant here.
5207 ConstantInt *Scale = 0;
5208 if (ArrayEltSize == 1) {
5209 NewIdx = GEP.getOperand(1);
5210 Scale = ConstantInt::get(NewIdx->getType(), 1);
5211 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
5212 NewIdx = ConstantInt::get(CI->getType(), 1);
5214 } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
5215 if (Inst->getOpcode() == Instruction::Shl &&
5216 isa<ConstantInt>(Inst->getOperand(1))) {
5217 unsigned ShAmt =cast<ConstantUInt>(Inst->getOperand(1))->getValue();
5218 if (Inst->getType()->isSigned())
5219 Scale = ConstantSInt::get(Inst->getType(), 1ULL << ShAmt);
5221 Scale = ConstantUInt::get(Inst->getType(), 1ULL << ShAmt);
5222 NewIdx = Inst->getOperand(0);
5223 } else if (Inst->getOpcode() == Instruction::Mul &&
5224 isa<ConstantInt>(Inst->getOperand(1))) {
5225 Scale = cast<ConstantInt>(Inst->getOperand(1));
5226 NewIdx = Inst->getOperand(0);
5230 // If the index will be to exactly the right offset with the scale taken
5231 // out, perform the transformation.
5232 if (Scale && Scale->getRawValue() % ArrayEltSize == 0) {
5233 if (ConstantSInt *C = dyn_cast<ConstantSInt>(Scale))
5234 Scale = ConstantSInt::get(C->getType(),
5235 (int64_t)C->getRawValue() /
5236 (int64_t)ArrayEltSize);
5238 Scale = ConstantUInt::get(Scale->getType(),
5239 Scale->getRawValue() / ArrayEltSize);
5240 if (Scale->getRawValue() != 1) {
5241 Constant *C = ConstantExpr::getCast(Scale, NewIdx->getType());
5242 Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale");
5243 NewIdx = InsertNewInstBefore(Sc, GEP);
5246 // Insert the new GEP instruction.
5248 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
5249 NewIdx, GEP.getName());
5250 Idx = InsertNewInstBefore(Idx, GEP);
5251 return new CastInst(Idx, GEP.getType());
5260 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
5261 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
5262 if (AI.isArrayAllocation()) // Check C != 1
5263 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
5264 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
5265 AllocationInst *New = 0;
5267 // Create and insert the replacement instruction...
5268 if (isa<MallocInst>(AI))
5269 New = new MallocInst(NewTy, 0, AI.getName());
5271 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
5272 New = new AllocaInst(NewTy, 0, AI.getName());
5275 InsertNewInstBefore(New, AI);
5277 // Scan to the end of the allocation instructions, to skip over a block of
5278 // allocas if possible...
5280 BasicBlock::iterator It = New;
5281 while (isa<AllocationInst>(*It)) ++It;
5283 // Now that I is pointing to the first non-allocation-inst in the block,
5284 // insert our getelementptr instruction...
5286 Value *NullIdx = Constant::getNullValue(Type::IntTy);
5287 Value *V = new GetElementPtrInst(New, NullIdx, NullIdx,
5288 New->getName()+".sub", It);
5290 // Now make everything use the getelementptr instead of the original
5292 return ReplaceInstUsesWith(AI, V);
5293 } else if (isa<UndefValue>(AI.getArraySize())) {
5294 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5297 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
5298 // Note that we only do this for alloca's, because malloc should allocate and
5299 // return a unique pointer, even for a zero byte allocation.
5300 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
5301 TD->getTypeSize(AI.getAllocatedType()) == 0)
5302 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5307 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
5308 Value *Op = FI.getOperand(0);
5310 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
5311 if (CastInst *CI = dyn_cast<CastInst>(Op))
5312 if (isa<PointerType>(CI->getOperand(0)->getType())) {
5313 FI.setOperand(0, CI->getOperand(0));
5317 // free undef -> unreachable.
5318 if (isa<UndefValue>(Op)) {
5319 // Insert a new store to null because we cannot modify the CFG here.
5320 new StoreInst(ConstantBool::True,
5321 UndefValue::get(PointerType::get(Type::BoolTy)), &FI);
5322 return EraseInstFromFunction(FI);
5325 // If we have 'free null' delete the instruction. This can happen in stl code
5326 // when lots of inlining happens.
5327 if (isa<ConstantPointerNull>(Op))
5328 return EraseInstFromFunction(FI);
5334 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
5335 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
5336 User *CI = cast<User>(LI.getOperand(0));
5337 Value *CastOp = CI->getOperand(0);
5339 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5340 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5341 const Type *SrcPTy = SrcTy->getElementType();
5343 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5344 // If the source is an array, the code below will not succeed. Check to
5345 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5347 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5348 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5349 if (ASrcTy->getNumElements() != 0) {
5350 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5351 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5352 SrcTy = cast<PointerType>(CastOp->getType());
5353 SrcPTy = SrcTy->getElementType();
5356 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5357 // Do not allow turning this into a load of an integer, which is then
5358 // casted to a pointer, this pessimizes pointer analysis a lot.
5359 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
5360 IC.getTargetData().getTypeSize(SrcPTy) ==
5361 IC.getTargetData().getTypeSize(DestPTy)) {
5363 // Okay, we are casting from one integer or pointer type to another of
5364 // the same size. Instead of casting the pointer before the load, cast
5365 // the result of the loaded value.
5366 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
5368 LI.isVolatile()),LI);
5369 // Now cast the result of the load.
5370 return new CastInst(NewLoad, LI.getType());
5377 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
5378 /// from this value cannot trap. If it is not obviously safe to load from the
5379 /// specified pointer, we do a quick local scan of the basic block containing
5380 /// ScanFrom, to determine if the address is already accessed.
5381 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
5382 // If it is an alloca or global variable, it is always safe to load from.
5383 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
5385 // Otherwise, be a little bit agressive by scanning the local block where we
5386 // want to check to see if the pointer is already being loaded or stored
5387 // from/to. If so, the previous load or store would have already trapped,
5388 // so there is no harm doing an extra load (also, CSE will later eliminate
5389 // the load entirely).
5390 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
5395 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
5396 if (LI->getOperand(0) == V) return true;
5397 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
5398 if (SI->getOperand(1) == V) return true;
5404 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
5405 Value *Op = LI.getOperand(0);
5407 // load (cast X) --> cast (load X) iff safe
5408 if (CastInst *CI = dyn_cast<CastInst>(Op))
5409 if (Instruction *Res = InstCombineLoadCast(*this, LI))
5412 // None of the following transforms are legal for volatile loads.
5413 if (LI.isVolatile()) return 0;
5415 if (&LI.getParent()->front() != &LI) {
5416 BasicBlock::iterator BBI = &LI; --BBI;
5417 // If the instruction immediately before this is a store to the same
5418 // address, do a simple form of store->load forwarding.
5419 if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
5420 if (SI->getOperand(1) == LI.getOperand(0))
5421 return ReplaceInstUsesWith(LI, SI->getOperand(0));
5422 if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
5423 if (LIB->getOperand(0) == LI.getOperand(0))
5424 return ReplaceInstUsesWith(LI, LIB);
5427 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
5428 if (isa<ConstantPointerNull>(GEPI->getOperand(0)) ||
5429 isa<UndefValue>(GEPI->getOperand(0))) {
5430 // Insert a new store to null instruction before the load to indicate
5431 // that this code is not reachable. We do this instead of inserting
5432 // an unreachable instruction directly because we cannot modify the
5434 new StoreInst(UndefValue::get(LI.getType()),
5435 Constant::getNullValue(Op->getType()), &LI);
5436 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5439 if (Constant *C = dyn_cast<Constant>(Op)) {
5440 // load null/undef -> undef
5441 if ((C->isNullValue() || isa<UndefValue>(C))) {
5442 // Insert a new store to null instruction before the load to indicate that
5443 // this code is not reachable. We do this instead of inserting an
5444 // unreachable instruction directly because we cannot modify the CFG.
5445 new StoreInst(UndefValue::get(LI.getType()),
5446 Constant::getNullValue(Op->getType()), &LI);
5447 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5450 // Instcombine load (constant global) into the value loaded.
5451 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
5452 if (GV->isConstant() && !GV->isExternal())
5453 return ReplaceInstUsesWith(LI, GV->getInitializer());
5455 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
5456 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
5457 if (CE->getOpcode() == Instruction::GetElementPtr) {
5458 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
5459 if (GV->isConstant() && !GV->isExternal())
5461 ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
5462 return ReplaceInstUsesWith(LI, V);
5463 if (CE->getOperand(0)->isNullValue()) {
5464 // Insert a new store to null instruction before the load to indicate
5465 // that this code is not reachable. We do this instead of inserting
5466 // an unreachable instruction directly because we cannot modify the
5468 new StoreInst(UndefValue::get(LI.getType()),
5469 Constant::getNullValue(Op->getType()), &LI);
5470 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5473 } else if (CE->getOpcode() == Instruction::Cast) {
5474 if (Instruction *Res = InstCombineLoadCast(*this, LI))
5479 if (Op->hasOneUse()) {
5480 // Change select and PHI nodes to select values instead of addresses: this
5481 // helps alias analysis out a lot, allows many others simplifications, and
5482 // exposes redundancy in the code.
5484 // Note that we cannot do the transformation unless we know that the
5485 // introduced loads cannot trap! Something like this is valid as long as
5486 // the condition is always false: load (select bool %C, int* null, int* %G),
5487 // but it would not be valid if we transformed it to load from null
5490 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
5491 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
5492 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
5493 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
5494 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
5495 SI->getOperand(1)->getName()+".val"), LI);
5496 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
5497 SI->getOperand(2)->getName()+".val"), LI);
5498 return new SelectInst(SI->getCondition(), V1, V2);
5501 // load (select (cond, null, P)) -> load P
5502 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
5503 if (C->isNullValue()) {
5504 LI.setOperand(0, SI->getOperand(2));
5508 // load (select (cond, P, null)) -> load P
5509 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
5510 if (C->isNullValue()) {
5511 LI.setOperand(0, SI->getOperand(1));
5515 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
5516 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
5517 bool Safe = PN->getParent() == LI.getParent();
5519 // Scan all of the instructions between the PHI and the load to make
5520 // sure there are no instructions that might possibly alter the value
5521 // loaded from the PHI.
5523 BasicBlock::iterator I = &LI;
5524 for (--I; !isa<PHINode>(I); --I)
5525 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
5531 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
5532 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
5533 PN->getIncomingBlock(i)->getTerminator()))
5538 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
5539 InsertNewInstBefore(NewPN, *PN);
5540 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
5542 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
5543 BasicBlock *BB = PN->getIncomingBlock(i);
5544 Value *&TheLoad = LoadMap[BB];
5546 Value *InVal = PN->getIncomingValue(i);
5547 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
5548 InVal->getName()+".val"),
5549 *BB->getTerminator());
5551 NewPN->addIncoming(TheLoad, BB);
5553 return ReplaceInstUsesWith(LI, NewPN);
5560 /// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store (cast V), P'
5562 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
5563 User *CI = cast<User>(SI.getOperand(1));
5564 Value *CastOp = CI->getOperand(0);
5566 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5567 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5568 const Type *SrcPTy = SrcTy->getElementType();
5570 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5571 // If the source is an array, the code below will not succeed. Check to
5572 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5574 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5575 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5576 if (ASrcTy->getNumElements() != 0) {
5577 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5578 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5579 SrcTy = cast<PointerType>(CastOp->getType());
5580 SrcPTy = SrcTy->getElementType();
5583 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5584 IC.getTargetData().getTypeSize(SrcPTy) ==
5585 IC.getTargetData().getTypeSize(DestPTy)) {
5587 // Okay, we are casting from one integer or pointer type to another of
5588 // the same size. Instead of casting the pointer before the store, cast
5589 // the value to be stored.
5591 if (Constant *C = dyn_cast<Constant>(SI.getOperand(0)))
5592 NewCast = ConstantExpr::getCast(C, SrcPTy);
5594 NewCast = IC.InsertNewInstBefore(new CastInst(SI.getOperand(0),
5596 SI.getOperand(0)->getName()+".c"), SI);
5598 return new StoreInst(NewCast, CastOp);
5605 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
5606 Value *Val = SI.getOperand(0);
5607 Value *Ptr = SI.getOperand(1);
5609 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
5610 removeFromWorkList(&SI);
5611 SI.eraseFromParent();
5616 if (SI.isVolatile()) return 0; // Don't hack volatile loads.
5618 // store X, null -> turns into 'unreachable' in SimplifyCFG
5619 if (isa<ConstantPointerNull>(Ptr)) {
5620 if (!isa<UndefValue>(Val)) {
5621 SI.setOperand(0, UndefValue::get(Val->getType()));
5622 if (Instruction *U = dyn_cast<Instruction>(Val))
5623 WorkList.push_back(U); // Dropped a use.
5626 return 0; // Do not modify these!
5629 // store undef, Ptr -> noop
5630 if (isa<UndefValue>(Val)) {
5631 removeFromWorkList(&SI);
5632 SI.eraseFromParent();
5637 // If the pointer destination is a cast, see if we can fold the cast into the
5639 if (CastInst *CI = dyn_cast<CastInst>(Ptr))
5640 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5642 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
5643 if (CE->getOpcode() == Instruction::Cast)
5644 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5648 // If this store is the last instruction in the basic block, and if the block
5649 // ends with an unconditional branch, try to move it to the successor block.
5650 BasicBlock::iterator BBI = &SI; ++BBI;
5651 if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
5652 if (BI->isUnconditional()) {
5653 // Check to see if the successor block has exactly two incoming edges. If
5654 // so, see if the other predecessor contains a store to the same location.
5655 // if so, insert a PHI node (if needed) and move the stores down.
5656 BasicBlock *Dest = BI->getSuccessor(0);
5658 pred_iterator PI = pred_begin(Dest);
5659 BasicBlock *Other = 0;
5660 if (*PI != BI->getParent())
5663 if (PI != pred_end(Dest)) {
5664 if (*PI != BI->getParent())
5669 if (++PI != pred_end(Dest))
5672 if (Other) { // If only one other pred...
5673 BBI = Other->getTerminator();
5674 // Make sure this other block ends in an unconditional branch and that
5675 // there is an instruction before the branch.
5676 if (isa<BranchInst>(BBI) && cast<BranchInst>(BBI)->isUnconditional() &&
5677 BBI != Other->begin()) {
5679 StoreInst *OtherStore = dyn_cast<StoreInst>(BBI);
5681 // If this instruction is a store to the same location.
5682 if (OtherStore && OtherStore->getOperand(1) == SI.getOperand(1)) {
5683 // Okay, we know we can perform this transformation. Insert a PHI
5684 // node now if we need it.
5685 Value *MergedVal = OtherStore->getOperand(0);
5686 if (MergedVal != SI.getOperand(0)) {
5687 PHINode *PN = new PHINode(MergedVal->getType(), "storemerge");
5688 PN->reserveOperandSpace(2);
5689 PN->addIncoming(SI.getOperand(0), SI.getParent());
5690 PN->addIncoming(OtherStore->getOperand(0), Other);
5691 MergedVal = InsertNewInstBefore(PN, Dest->front());
5694 // Advance to a place where it is safe to insert the new store and
5696 BBI = Dest->begin();
5697 while (isa<PHINode>(BBI)) ++BBI;
5698 InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
5699 OtherStore->isVolatile()), *BBI);
5701 // Nuke the old stores.
5702 removeFromWorkList(&SI);
5703 removeFromWorkList(OtherStore);
5704 SI.eraseFromParent();
5705 OtherStore->eraseFromParent();
5717 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
5718 // Change br (not X), label True, label False to: br X, label False, True
5720 BasicBlock *TrueDest;
5721 BasicBlock *FalseDest;
5722 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
5723 !isa<Constant>(X)) {
5724 // Swap Destinations and condition...
5726 BI.setSuccessor(0, FalseDest);
5727 BI.setSuccessor(1, TrueDest);
5731 // Cannonicalize setne -> seteq
5732 Instruction::BinaryOps Op; Value *Y;
5733 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
5734 TrueDest, FalseDest)))
5735 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
5736 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
5737 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
5738 std::string Name = I->getName(); I->setName("");
5739 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
5740 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
5741 // Swap Destinations and condition...
5742 BI.setCondition(NewSCC);
5743 BI.setSuccessor(0, FalseDest);
5744 BI.setSuccessor(1, TrueDest);
5745 removeFromWorkList(I);
5746 I->getParent()->getInstList().erase(I);
5747 WorkList.push_back(cast<Instruction>(NewSCC));
5754 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
5755 Value *Cond = SI.getCondition();
5756 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
5757 if (I->getOpcode() == Instruction::Add)
5758 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
5759 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
5760 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
5761 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
5763 SI.setOperand(0, I->getOperand(0));
5764 WorkList.push_back(I);
5771 void InstCombiner::removeFromWorkList(Instruction *I) {
5772 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
5777 /// TryToSinkInstruction - Try to move the specified instruction from its
5778 /// current block into the beginning of DestBlock, which can only happen if it's
5779 /// safe to move the instruction past all of the instructions between it and the
5780 /// end of its block.
5781 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
5782 assert(I->hasOneUse() && "Invariants didn't hold!");
5784 // Cannot move control-flow-involving, volatile loads, vaarg, etc.
5785 if (isa<PHINode>(I) || I->mayWriteToMemory()) return false;
5787 // Do not sink alloca instructions out of the entry block.
5788 if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front())
5791 // We can only sink load instructions if there is nothing between the load and
5792 // the end of block that could change the value.
5793 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
5794 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
5796 if (Scan->mayWriteToMemory())
5800 BasicBlock::iterator InsertPos = DestBlock->begin();
5801 while (isa<PHINode>(InsertPos)) ++InsertPos;
5803 I->moveBefore(InsertPos);
5808 bool InstCombiner::runOnFunction(Function &F) {
5809 bool Changed = false;
5810 TD = &getAnalysis<TargetData>();
5813 // Populate the worklist with the reachable instructions.
5814 std::set<BasicBlock*> Visited;
5815 for (df_ext_iterator<BasicBlock*> BB = df_ext_begin(&F.front(), Visited),
5816 E = df_ext_end(&F.front(), Visited); BB != E; ++BB)
5817 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
5818 WorkList.push_back(I);
5820 // Do a quick scan over the function. If we find any blocks that are
5821 // unreachable, remove any instructions inside of them. This prevents
5822 // the instcombine code from having to deal with some bad special cases.
5823 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
5824 if (!Visited.count(BB)) {
5825 Instruction *Term = BB->getTerminator();
5826 while (Term != BB->begin()) { // Remove instrs bottom-up
5827 BasicBlock::iterator I = Term; --I;
5829 DEBUG(std::cerr << "IC: DCE: " << *I);
5832 if (!I->use_empty())
5833 I->replaceAllUsesWith(UndefValue::get(I->getType()));
5834 I->eraseFromParent();
5839 while (!WorkList.empty()) {
5840 Instruction *I = WorkList.back(); // Get an instruction from the worklist
5841 WorkList.pop_back();
5843 // Check to see if we can DCE or ConstantPropagate the instruction...
5844 // Check to see if we can DIE the instruction...
5845 if (isInstructionTriviallyDead(I)) {
5846 // Add operands to the worklist...
5847 if (I->getNumOperands() < 4)
5848 AddUsesToWorkList(*I);
5851 DEBUG(std::cerr << "IC: DCE: " << *I);
5853 I->eraseFromParent();
5854 removeFromWorkList(I);
5858 // Instruction isn't dead, see if we can constant propagate it...
5859 if (Constant *C = ConstantFoldInstruction(I)) {
5860 Value* Ptr = I->getOperand(0);
5861 if (isa<GetElementPtrInst>(I) &&
5862 cast<Constant>(Ptr)->isNullValue() &&
5863 !isa<ConstantPointerNull>(C) &&
5864 cast<PointerType>(Ptr->getType())->getElementType()->isSized()) {
5865 // If this is a constant expr gep that is effectively computing an
5866 // "offsetof", fold it into 'cast int X to T*' instead of 'gep 0, 0, 12'
5867 bool isFoldableGEP = true;
5868 for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
5869 if (!isa<ConstantInt>(I->getOperand(i)))
5870 isFoldableGEP = false;
5871 if (isFoldableGEP) {
5872 uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
5873 std::vector<Value*>(I->op_begin()+1, I->op_end()));
5874 C = ConstantUInt::get(Type::ULongTy, Offset);
5875 C = ConstantExpr::getCast(C, TD->getIntPtrType());
5876 C = ConstantExpr::getCast(C, I->getType());
5880 DEBUG(std::cerr << "IC: ConstFold to: " << *C << " from: " << *I);
5882 // Add operands to the worklist...
5883 AddUsesToWorkList(*I);
5884 ReplaceInstUsesWith(*I, C);
5887 I->getParent()->getInstList().erase(I);
5888 removeFromWorkList(I);
5892 // See if we can trivially sink this instruction to a successor basic block.
5893 if (I->hasOneUse()) {
5894 BasicBlock *BB = I->getParent();
5895 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
5896 if (UserParent != BB) {
5897 bool UserIsSuccessor = false;
5898 // See if the user is one of our successors.
5899 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
5900 if (*SI == UserParent) {
5901 UserIsSuccessor = true;
5905 // If the user is one of our immediate successors, and if that successor
5906 // only has us as a predecessors (we'd have to split the critical edge
5907 // otherwise), we can keep going.
5908 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
5909 next(pred_begin(UserParent)) == pred_end(UserParent))
5910 // Okay, the CFG is simple enough, try to sink this instruction.
5911 Changed |= TryToSinkInstruction(I, UserParent);
5915 // Now that we have an instruction, try combining it to simplify it...
5916 if (Instruction *Result = visit(*I)) {
5918 // Should we replace the old instruction with a new one?
5920 DEBUG(std::cerr << "IC: Old = " << *I
5921 << " New = " << *Result);
5923 // Everything uses the new instruction now.
5924 I->replaceAllUsesWith(Result);
5926 // Push the new instruction and any users onto the worklist.
5927 WorkList.push_back(Result);
5928 AddUsersToWorkList(*Result);
5930 // Move the name to the new instruction first...
5931 std::string OldName = I->getName(); I->setName("");
5932 Result->setName(OldName);
5934 // Insert the new instruction into the basic block...
5935 BasicBlock *InstParent = I->getParent();
5936 BasicBlock::iterator InsertPos = I;
5938 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
5939 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
5942 InstParent->getInstList().insert(InsertPos, Result);
5944 // Make sure that we reprocess all operands now that we reduced their
5946 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
5947 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
5948 WorkList.push_back(OpI);
5950 // Instructions can end up on the worklist more than once. Make sure
5951 // we do not process an instruction that has been deleted.
5952 removeFromWorkList(I);
5954 // Erase the old instruction.
5955 InstParent->getInstList().erase(I);
5957 DEBUG(std::cerr << "IC: MOD = " << *I);
5959 // If the instruction was modified, it's possible that it is now dead.
5960 // if so, remove it.
5961 if (isInstructionTriviallyDead(I)) {
5962 // Make sure we process all operands now that we are reducing their
5964 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
5965 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
5966 WorkList.push_back(OpI);
5968 // Instructions may end up in the worklist more than once. Erase all
5969 // occurrances of this instruction.
5970 removeFromWorkList(I);
5971 I->eraseFromParent();
5973 WorkList.push_back(Result);
5974 AddUsersToWorkList(*Result);
5984 FunctionPass *llvm::createInstructionCombiningPass() {
5985 return new InstCombiner();