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"
57 using namespace llvm::PatternMatch;
60 Statistic<> NumCombined ("instcombine", "Number of insts combined");
61 Statistic<> NumConstProp("instcombine", "Number of constant folds");
62 Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
63 Statistic<> NumSunkInst ("instcombine", "Number of instructions sunk");
65 class InstCombiner : public FunctionPass,
66 public InstVisitor<InstCombiner, Instruction*> {
67 // Worklist of all of the instructions that need to be simplified.
68 std::vector<Instruction*> WorkList;
71 /// AddUsersToWorkList - When an instruction is simplified, add all users of
72 /// the instruction to the work lists because they might get more simplified
75 void AddUsersToWorkList(Instruction &I) {
76 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
78 WorkList.push_back(cast<Instruction>(*UI));
81 /// AddUsesToWorkList - When an instruction is simplified, add operands to
82 /// the work lists because they might get more simplified now.
84 void AddUsesToWorkList(Instruction &I) {
85 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
86 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
87 WorkList.push_back(Op);
90 // removeFromWorkList - remove all instances of I from the worklist.
91 void removeFromWorkList(Instruction *I);
93 virtual bool runOnFunction(Function &F);
95 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
96 AU.addRequired<TargetData>();
100 TargetData &getTargetData() const { return *TD; }
102 // Visitation implementation - Implement instruction combining for different
103 // instruction types. The semantics are as follows:
105 // null - No change was made
106 // I - Change was made, I is still valid, I may be dead though
107 // otherwise - Change was made, replace I with returned instruction
109 Instruction *visitAdd(BinaryOperator &I);
110 Instruction *visitSub(BinaryOperator &I);
111 Instruction *visitMul(BinaryOperator &I);
112 Instruction *visitDiv(BinaryOperator &I);
113 Instruction *visitRem(BinaryOperator &I);
114 Instruction *visitAnd(BinaryOperator &I);
115 Instruction *visitOr (BinaryOperator &I);
116 Instruction *visitXor(BinaryOperator &I);
117 Instruction *visitSetCondInst(SetCondInst &I);
118 Instruction *visitSetCondInstWithCastAndCast(SetCondInst &SCI);
120 Instruction *FoldGEPSetCC(User *GEPLHS, Value *RHS,
121 Instruction::BinaryOps Cond, Instruction &I);
122 Instruction *visitShiftInst(ShiftInst &I);
123 Instruction *FoldShiftByConstant(Value *Op0, ConstantUInt *Op1,
125 Instruction *visitCastInst(CastInst &CI);
126 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
128 Instruction *visitSelectInst(SelectInst &CI);
129 Instruction *visitCallInst(CallInst &CI);
130 Instruction *visitInvokeInst(InvokeInst &II);
131 Instruction *visitPHINode(PHINode &PN);
132 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
133 Instruction *visitAllocationInst(AllocationInst &AI);
134 Instruction *visitFreeInst(FreeInst &FI);
135 Instruction *visitLoadInst(LoadInst &LI);
136 Instruction *visitStoreInst(StoreInst &SI);
137 Instruction *visitBranchInst(BranchInst &BI);
138 Instruction *visitSwitchInst(SwitchInst &SI);
139 Instruction *visitExtractElementInst(ExtractElementInst &EI);
141 // visitInstruction - Specify what to return for unhandled instructions...
142 Instruction *visitInstruction(Instruction &I) { return 0; }
145 Instruction *visitCallSite(CallSite CS);
146 bool transformConstExprCastCall(CallSite CS);
149 // InsertNewInstBefore - insert an instruction New before instruction Old
150 // in the program. Add the new instruction to the worklist.
152 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
153 assert(New && New->getParent() == 0 &&
154 "New instruction already inserted into a basic block!");
155 BasicBlock *BB = Old.getParent();
156 BB->getInstList().insert(&Old, New); // Insert inst
157 WorkList.push_back(New); // Add to worklist
161 /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
162 /// This also adds the cast to the worklist. Finally, this returns the
164 Value *InsertCastBefore(Value *V, const Type *Ty, Instruction &Pos) {
165 if (V->getType() == Ty) return V;
167 Instruction *C = new CastInst(V, Ty, V->getName(), &Pos);
168 WorkList.push_back(C);
172 // ReplaceInstUsesWith - This method is to be used when an instruction is
173 // found to be dead, replacable with another preexisting expression. Here
174 // we add all uses of I to the worklist, replace all uses of I with the new
175 // value, then return I, so that the inst combiner will know that I was
178 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
179 AddUsersToWorkList(I); // Add all modified instrs to worklist
181 I.replaceAllUsesWith(V);
184 // If we are replacing the instruction with itself, this must be in a
185 // segment of unreachable code, so just clobber the instruction.
186 I.replaceAllUsesWith(UndefValue::get(I.getType()));
191 // EraseInstFromFunction - When dealing with an instruction that has side
192 // effects or produces a void value, we can't rely on DCE to delete the
193 // instruction. Instead, visit methods should return the value returned by
195 Instruction *EraseInstFromFunction(Instruction &I) {
196 assert(I.use_empty() && "Cannot erase instruction that is used!");
197 AddUsesToWorkList(I);
198 removeFromWorkList(&I);
200 return 0; // Don't do anything with FI
205 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
206 /// InsertBefore instruction. This is specialized a bit to avoid inserting
207 /// casts that are known to not do anything...
209 Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
210 Instruction *InsertBefore);
212 // SimplifyCommutative - This performs a few simplifications for commutative
214 bool SimplifyCommutative(BinaryOperator &I);
217 // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
218 // PHI node as operand #0, see if we can fold the instruction into the PHI
219 // (which is only possible if all operands to the PHI are constants).
220 Instruction *FoldOpIntoPhi(Instruction &I);
222 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
223 // operator and they all are only used by the PHI, PHI together their
224 // inputs, and do the operation once, to the result of the PHI.
225 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
227 Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
228 ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
230 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantIntegral *Mask,
231 bool isSub, Instruction &I);
232 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
233 bool Inside, Instruction &IB);
234 Instruction *PromoteCastOfAllocation(CastInst &CI, AllocationInst &AI);
237 RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
240 // getComplexity: Assign a complexity or rank value to LLVM Values...
241 // 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
242 static unsigned getComplexity(Value *V) {
243 if (isa<Instruction>(V)) {
244 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
248 if (isa<Argument>(V)) return 3;
249 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
252 // isOnlyUse - Return true if this instruction will be deleted if we stop using
254 static bool isOnlyUse(Value *V) {
255 return V->hasOneUse() || isa<Constant>(V);
258 // getPromotedType - Return the specified type promoted as it would be to pass
259 // though a va_arg area...
260 static const Type *getPromotedType(const Type *Ty) {
261 switch (Ty->getTypeID()) {
262 case Type::SByteTyID:
263 case Type::ShortTyID: return Type::IntTy;
264 case Type::UByteTyID:
265 case Type::UShortTyID: return Type::UIntTy;
266 case Type::FloatTyID: return Type::DoubleTy;
271 /// isCast - If the specified operand is a CastInst or a constant expr cast,
272 /// return the operand value, otherwise return null.
273 static Value *isCast(Value *V) {
274 if (CastInst *I = dyn_cast<CastInst>(V))
275 return I->getOperand(0);
276 else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
277 if (CE->getOpcode() == Instruction::Cast)
278 return CE->getOperand(0);
282 // SimplifyCommutative - This performs a few simplifications for commutative
285 // 1. Order operands such that they are listed from right (least complex) to
286 // left (most complex). This puts constants before unary operators before
289 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
290 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
292 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
293 bool Changed = false;
294 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
295 Changed = !I.swapOperands();
297 if (!I.isAssociative()) return Changed;
298 Instruction::BinaryOps Opcode = I.getOpcode();
299 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
300 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
301 if (isa<Constant>(I.getOperand(1))) {
302 Constant *Folded = ConstantExpr::get(I.getOpcode(),
303 cast<Constant>(I.getOperand(1)),
304 cast<Constant>(Op->getOperand(1)));
305 I.setOperand(0, Op->getOperand(0));
306 I.setOperand(1, Folded);
308 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
309 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
310 isOnlyUse(Op) && isOnlyUse(Op1)) {
311 Constant *C1 = cast<Constant>(Op->getOperand(1));
312 Constant *C2 = cast<Constant>(Op1->getOperand(1));
314 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
315 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
316 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
319 WorkList.push_back(New);
320 I.setOperand(0, New);
321 I.setOperand(1, Folded);
328 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
329 // if the LHS is a constant zero (which is the 'negate' form).
331 static inline Value *dyn_castNegVal(Value *V) {
332 if (BinaryOperator::isNeg(V))
333 return BinaryOperator::getNegArgument(V);
335 // Constants can be considered to be negated values if they can be folded.
336 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
337 return ConstantExpr::getNeg(C);
341 static inline Value *dyn_castNotVal(Value *V) {
342 if (BinaryOperator::isNot(V))
343 return BinaryOperator::getNotArgument(V);
345 // Constants can be considered to be not'ed values...
346 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
347 return ConstantExpr::getNot(C);
351 // dyn_castFoldableMul - If this value is a multiply that can be folded into
352 // other computations (because it has a constant operand), return the
353 // non-constant operand of the multiply, and set CST to point to the multiplier.
354 // Otherwise, return null.
356 static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
357 if (V->hasOneUse() && V->getType()->isInteger())
358 if (Instruction *I = dyn_cast<Instruction>(V)) {
359 if (I->getOpcode() == Instruction::Mul)
360 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
361 return I->getOperand(0);
362 if (I->getOpcode() == Instruction::Shl)
363 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
364 // The multiplier is really 1 << CST.
365 Constant *One = ConstantInt::get(V->getType(), 1);
366 CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
367 return I->getOperand(0);
373 /// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
374 /// expression, return it.
375 static User *dyn_castGetElementPtr(Value *V) {
376 if (isa<GetElementPtrInst>(V)) return cast<User>(V);
377 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
378 if (CE->getOpcode() == Instruction::GetElementPtr)
379 return cast<User>(V);
383 // AddOne, SubOne - Add or subtract a constant one from an integer constant...
384 static ConstantInt *AddOne(ConstantInt *C) {
385 return cast<ConstantInt>(ConstantExpr::getAdd(C,
386 ConstantInt::get(C->getType(), 1)));
388 static ConstantInt *SubOne(ConstantInt *C) {
389 return cast<ConstantInt>(ConstantExpr::getSub(C,
390 ConstantInt::get(C->getType(), 1)));
393 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
394 /// this predicate to simplify operations downstream. V and Mask are known to
395 /// be the same type.
396 static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask,
397 unsigned Depth = 0) {
398 // Note, we cannot consider 'undef' to be "IsZero" here. The problem is that
399 // we cannot optimize based on the assumption that it is zero without changing
400 // to to an explicit zero. If we don't change it to zero, other code could
401 // optimized based on the contradictory assumption that it is non-zero.
402 // Because instcombine aggressively folds operations with undef args anyway,
403 // this won't lose us code quality.
404 if (Mask->isNullValue())
406 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
407 return ConstantExpr::getAnd(CI, Mask)->isNullValue();
409 if (Depth == 6) return false; // Limit search depth.
411 if (Instruction *I = dyn_cast<Instruction>(V)) {
412 switch (I->getOpcode()) {
413 case Instruction::And:
414 // (X & C1) & C2 == 0 iff C1 & C2 == 0.
415 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1))) {
416 ConstantIntegral *C1C2 =
417 cast<ConstantIntegral>(ConstantExpr::getAnd(CI, Mask));
418 if (MaskedValueIsZero(I->getOperand(0), C1C2, Depth+1))
421 // If either the LHS or the RHS are MaskedValueIsZero, the result is zero.
422 return MaskedValueIsZero(I->getOperand(1), Mask, Depth+1) ||
423 MaskedValueIsZero(I->getOperand(0), Mask, Depth+1);
424 case Instruction::Or:
425 case Instruction::Xor:
426 // If the LHS and the RHS are MaskedValueIsZero, the result is also zero.
427 return MaskedValueIsZero(I->getOperand(1), Mask, Depth+1) &&
428 MaskedValueIsZero(I->getOperand(0), Mask, Depth+1);
429 case Instruction::Select:
430 // If the T and F values are MaskedValueIsZero, the result is also zero.
431 return MaskedValueIsZero(I->getOperand(2), Mask, Depth+1) &&
432 MaskedValueIsZero(I->getOperand(1), Mask, Depth+1);
433 case Instruction::Cast: {
434 const Type *SrcTy = I->getOperand(0)->getType();
435 if (SrcTy == Type::BoolTy)
436 return (Mask->getRawValue() & 1) == 0;
438 if (SrcTy->isInteger()) {
439 // (cast <ty> X to int) & C2 == 0 iff <ty> could not have contained C2.
440 if (SrcTy->isUnsigned() && // Only handle zero ext.
441 ConstantExpr::getCast(Mask, SrcTy)->isNullValue())
444 // If this is a noop cast, recurse.
445 if ((SrcTy->isSigned() && SrcTy->getUnsignedVersion() == I->getType())||
446 SrcTy->getSignedVersion() == I->getType()) {
448 ConstantExpr::getCast(Mask, I->getOperand(0)->getType());
449 return MaskedValueIsZero(I->getOperand(0),
450 cast<ConstantIntegral>(NewMask), Depth+1);
455 case Instruction::Shl:
456 // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
457 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
458 return MaskedValueIsZero(I->getOperand(0),
459 cast<ConstantIntegral>(ConstantExpr::getUShr(Mask, SA)),
462 case Instruction::Shr:
463 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
464 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
465 if (I->getType()->isUnsigned()) {
466 Constant *C1 = ConstantIntegral::getAllOnesValue(I->getType());
467 C1 = ConstantExpr::getShr(C1, SA);
468 C1 = ConstantExpr::getAnd(C1, Mask);
469 if (C1->isNullValue())
479 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
480 // true when both operands are equal...
482 static bool isTrueWhenEqual(Instruction &I) {
483 return I.getOpcode() == Instruction::SetEQ ||
484 I.getOpcode() == Instruction::SetGE ||
485 I.getOpcode() == Instruction::SetLE;
488 /// AssociativeOpt - Perform an optimization on an associative operator. This
489 /// function is designed to check a chain of associative operators for a
490 /// potential to apply a certain optimization. Since the optimization may be
491 /// applicable if the expression was reassociated, this checks the chain, then
492 /// reassociates the expression as necessary to expose the optimization
493 /// opportunity. This makes use of a special Functor, which must define
494 /// 'shouldApply' and 'apply' methods.
496 template<typename Functor>
497 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
498 unsigned Opcode = Root.getOpcode();
499 Value *LHS = Root.getOperand(0);
501 // Quick check, see if the immediate LHS matches...
502 if (F.shouldApply(LHS))
503 return F.apply(Root);
505 // Otherwise, if the LHS is not of the same opcode as the root, return.
506 Instruction *LHSI = dyn_cast<Instruction>(LHS);
507 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
508 // Should we apply this transform to the RHS?
509 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
511 // If not to the RHS, check to see if we should apply to the LHS...
512 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
513 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
517 // If the functor wants to apply the optimization to the RHS of LHSI,
518 // reassociate the expression from ((? op A) op B) to (? op (A op B))
520 BasicBlock *BB = Root.getParent();
522 // Now all of the instructions are in the current basic block, go ahead
523 // and perform the reassociation.
524 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
526 // First move the selected RHS to the LHS of the root...
527 Root.setOperand(0, LHSI->getOperand(1));
529 // Make what used to be the LHS of the root be the user of the root...
530 Value *ExtraOperand = TmpLHSI->getOperand(1);
531 if (&Root == TmpLHSI) {
532 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
535 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
536 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
537 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
538 BasicBlock::iterator ARI = &Root; ++ARI;
539 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
542 // Now propagate the ExtraOperand down the chain of instructions until we
544 while (TmpLHSI != LHSI) {
545 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
546 // Move the instruction to immediately before the chain we are
547 // constructing to avoid breaking dominance properties.
548 NextLHSI->getParent()->getInstList().remove(NextLHSI);
549 BB->getInstList().insert(ARI, NextLHSI);
552 Value *NextOp = NextLHSI->getOperand(1);
553 NextLHSI->setOperand(1, ExtraOperand);
555 ExtraOperand = NextOp;
558 // Now that the instructions are reassociated, have the functor perform
559 // the transformation...
560 return F.apply(Root);
563 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
569 // AddRHS - Implements: X + X --> X << 1
572 AddRHS(Value *rhs) : RHS(rhs) {}
573 bool shouldApply(Value *LHS) const { return LHS == RHS; }
574 Instruction *apply(BinaryOperator &Add) const {
575 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
576 ConstantInt::get(Type::UByteTy, 1));
580 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
582 struct AddMaskingAnd {
584 AddMaskingAnd(Constant *c) : C2(c) {}
585 bool shouldApply(Value *LHS) const {
587 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
588 ConstantExpr::getAnd(C1, C2)->isNullValue();
590 Instruction *apply(BinaryOperator &Add) const {
591 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
595 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
597 if (isa<CastInst>(I)) {
598 if (Constant *SOC = dyn_cast<Constant>(SO))
599 return ConstantExpr::getCast(SOC, I.getType());
601 return IC->InsertNewInstBefore(new CastInst(SO, I.getType(),
602 SO->getName() + ".cast"), I);
605 // Figure out if the constant is the left or the right argument.
606 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
607 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
609 if (Constant *SOC = dyn_cast<Constant>(SO)) {
611 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
612 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
615 Value *Op0 = SO, *Op1 = ConstOperand;
619 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
620 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
621 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&I))
622 New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh");
624 assert(0 && "Unknown binary instruction type!");
627 return IC->InsertNewInstBefore(New, I);
630 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
631 // constant as the other operand, try to fold the binary operator into the
632 // select arguments. This also works for Cast instructions, which obviously do
633 // not have a second operand.
634 static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
636 // Don't modify shared select instructions
637 if (!SI->hasOneUse()) return 0;
638 Value *TV = SI->getOperand(1);
639 Value *FV = SI->getOperand(2);
641 if (isa<Constant>(TV) || isa<Constant>(FV)) {
642 // Bool selects with constant operands can be folded to logical ops.
643 if (SI->getType() == Type::BoolTy) return 0;
645 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
646 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
648 return new SelectInst(SI->getCondition(), SelectTrueVal,
655 /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
656 /// node as operand #0, see if we can fold the instruction into the PHI (which
657 /// is only possible if all operands to the PHI are constants).
658 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
659 PHINode *PN = cast<PHINode>(I.getOperand(0));
660 unsigned NumPHIValues = PN->getNumIncomingValues();
661 if (!PN->hasOneUse() || NumPHIValues == 0 ||
662 !isa<Constant>(PN->getIncomingValue(0))) return 0;
664 // Check to see if all of the operands of the PHI are constants. If not, we
665 // cannot do the transformation.
666 for (unsigned i = 1; i != NumPHIValues; ++i)
667 if (!isa<Constant>(PN->getIncomingValue(i)))
670 // Okay, we can do the transformation: create the new PHI node.
671 PHINode *NewPN = new PHINode(I.getType(), I.getName());
673 NewPN->reserveOperandSpace(PN->getNumOperands()/2);
674 InsertNewInstBefore(NewPN, *PN);
676 // Next, add all of the operands to the PHI.
677 if (I.getNumOperands() == 2) {
678 Constant *C = cast<Constant>(I.getOperand(1));
679 for (unsigned i = 0; i != NumPHIValues; ++i) {
680 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
681 NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
682 PN->getIncomingBlock(i));
685 assert(isa<CastInst>(I) && "Unary op should be a cast!");
686 const Type *RetTy = I.getType();
687 for (unsigned i = 0; i != NumPHIValues; ++i) {
688 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
689 NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
690 PN->getIncomingBlock(i));
693 return ReplaceInstUsesWith(I, NewPN);
696 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
697 bool Changed = SimplifyCommutative(I);
698 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
700 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
701 // X + undef -> undef
702 if (isa<UndefValue>(RHS))
703 return ReplaceInstUsesWith(I, RHS);
706 if (!I.getType()->isFloatingPoint()) { // NOTE: -0 + +0 = +0.
707 if (RHSC->isNullValue())
708 return ReplaceInstUsesWith(I, LHS);
709 } else if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
710 if (CFP->isExactlyValue(-0.0))
711 return ReplaceInstUsesWith(I, LHS);
714 // X + (signbit) --> X ^ signbit
715 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
716 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
717 uint64_t Val = CI->getRawValue() & (~0ULL >> (64- NumBits));
718 if (Val == (1ULL << (NumBits-1)))
719 return BinaryOperator::createXor(LHS, RHS);
722 if (isa<PHINode>(LHS))
723 if (Instruction *NV = FoldOpIntoPhi(I))
726 ConstantInt *XorRHS = 0;
728 if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
729 unsigned TySizeBits = I.getType()->getPrimitiveSizeInBits();
730 int64_t RHSSExt = cast<ConstantInt>(RHSC)->getSExtValue();
731 uint64_t RHSZExt = cast<ConstantInt>(RHSC)->getZExtValue();
733 uint64_t C0080Val = 1ULL << 31;
734 int64_t CFF80Val = -C0080Val;
737 if (TySizeBits > Size) {
739 // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
740 // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
741 if (RHSSExt == CFF80Val) {
742 if (XorRHS->getZExtValue() == C0080Val)
744 } else if (RHSZExt == C0080Val) {
745 if (XorRHS->getSExtValue() == CFF80Val)
749 // This is a sign extend if the top bits are known zero.
750 Constant *Mask = ConstantInt::getAllOnesValue(XorLHS->getType());
751 Mask = ConstantExpr::getShl(Mask,
752 ConstantInt::get(Type::UByteTy, 64-(TySizeBits-Size)));
753 if (!MaskedValueIsZero(XorLHS, cast<ConstantInt>(Mask)))
754 Size = 0; // Not a sign ext, but can't be any others either.
764 const Type *MiddleType = 0;
767 case 32: MiddleType = Type::IntTy; break;
768 case 16: MiddleType = Type::ShortTy; break;
769 case 8: MiddleType = Type::SByteTy; break;
772 Instruction *NewTrunc = new CastInst(XorLHS, MiddleType, "sext");
773 InsertNewInstBefore(NewTrunc, I);
774 return new CastInst(NewTrunc, I.getType());
780 if (I.getType()->isInteger()) {
781 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
783 if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
784 if (RHSI->getOpcode() == Instruction::Sub)
785 if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
786 return ReplaceInstUsesWith(I, RHSI->getOperand(0));
788 if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
789 if (LHSI->getOpcode() == Instruction::Sub)
790 if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
791 return ReplaceInstUsesWith(I, LHSI->getOperand(0));
796 if (Value *V = dyn_castNegVal(LHS))
797 return BinaryOperator::createSub(RHS, V);
800 if (!isa<Constant>(RHS))
801 if (Value *V = dyn_castNegVal(RHS))
802 return BinaryOperator::createSub(LHS, V);
806 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
807 if (X == RHS) // X*C + X --> X * (C+1)
808 return BinaryOperator::createMul(RHS, AddOne(C2));
810 // X*C1 + X*C2 --> X * (C1+C2)
812 if (X == dyn_castFoldableMul(RHS, C1))
813 return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2));
816 // X + X*C --> X * (C+1)
817 if (dyn_castFoldableMul(RHS, C2) == LHS)
818 return BinaryOperator::createMul(LHS, AddOne(C2));
821 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
822 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
823 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
825 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
827 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
828 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
829 return BinaryOperator::createSub(C, X);
832 // (X & FF00) + xx00 -> (X+xx00) & FF00
833 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
834 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
836 // See if all bits from the first bit set in the Add RHS up are included
837 // in the mask. First, get the rightmost bit.
838 uint64_t AddRHSV = CRHS->getRawValue();
840 // Form a mask of all bits from the lowest bit added through the top.
841 uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
842 AddRHSHighBits &= ~0ULL >> (64-C2->getType()->getPrimitiveSizeInBits());
844 // See if the and mask includes all of these bits.
845 uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue();
847 if (AddRHSHighBits == AddRHSHighBitsAnd) {
848 // Okay, the xform is safe. Insert the new add pronto.
849 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
851 return BinaryOperator::createAnd(NewAdd, C2);
856 // Try to fold constant add into select arguments.
857 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
858 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
862 return Changed ? &I : 0;
865 // isSignBit - Return true if the value represented by the constant only has the
866 // highest order bit set.
867 static bool isSignBit(ConstantInt *CI) {
868 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
869 return (CI->getRawValue() & (~0ULL >> (64-NumBits))) == (1ULL << (NumBits-1));
872 /// RemoveNoopCast - Strip off nonconverting casts from the value.
874 static Value *RemoveNoopCast(Value *V) {
875 if (CastInst *CI = dyn_cast<CastInst>(V)) {
876 const Type *CTy = CI->getType();
877 const Type *OpTy = CI->getOperand(0)->getType();
878 if (CTy->isInteger() && OpTy->isInteger()) {
879 if (CTy->getPrimitiveSizeInBits() == OpTy->getPrimitiveSizeInBits())
880 return RemoveNoopCast(CI->getOperand(0));
881 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
882 return RemoveNoopCast(CI->getOperand(0));
887 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
888 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
890 if (Op0 == Op1) // sub X, X -> 0
891 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
893 // If this is a 'B = x-(-A)', change to B = x+A...
894 if (Value *V = dyn_castNegVal(Op1))
895 return BinaryOperator::createAdd(Op0, V);
897 if (isa<UndefValue>(Op0))
898 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
899 if (isa<UndefValue>(Op1))
900 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
902 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
903 // Replace (-1 - A) with (~A)...
904 if (C->isAllOnesValue())
905 return BinaryOperator::createNot(Op1);
907 // C - ~X == X + (1+C)
909 if (match(Op1, m_Not(m_Value(X))))
910 return BinaryOperator::createAdd(X,
911 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
912 // -((uint)X >> 31) -> ((int)X >> 31)
913 // -((int)X >> 31) -> ((uint)X >> 31)
914 if (C->isNullValue()) {
915 Value *NoopCastedRHS = RemoveNoopCast(Op1);
916 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
917 if (SI->getOpcode() == Instruction::Shr)
918 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
920 if (SI->getType()->isSigned())
921 NewTy = SI->getType()->getUnsignedVersion();
923 NewTy = SI->getType()->getSignedVersion();
924 // Check to see if we are shifting out everything but the sign bit.
925 if (CU->getValue() == SI->getType()->getPrimitiveSizeInBits()-1) {
926 // Ok, the transformation is safe. Insert a cast of the incoming
927 // value, then the new shift, then the new cast.
928 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
929 SI->getOperand(0)->getName());
930 Value *InV = InsertNewInstBefore(FirstCast, I);
931 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
933 if (NewShift->getType() == I.getType())
936 InV = InsertNewInstBefore(NewShift, I);
937 return new CastInst(NewShift, I.getType());
943 // Try to fold constant sub into select arguments.
944 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
945 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
948 if (isa<PHINode>(Op0))
949 if (Instruction *NV = FoldOpIntoPhi(I))
953 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
954 if (Op1I->getOpcode() == Instruction::Add &&
955 !Op0->getType()->isFloatingPoint()) {
956 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
957 return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
958 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
959 return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
960 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
961 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
962 // C1-(X+C2) --> (C1-C2)-X
963 return BinaryOperator::createSub(ConstantExpr::getSub(CI1, CI2),
964 Op1I->getOperand(0));
968 if (Op1I->hasOneUse()) {
969 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
970 // is not used by anyone else...
972 if (Op1I->getOpcode() == Instruction::Sub &&
973 !Op1I->getType()->isFloatingPoint()) {
974 // Swap the two operands of the subexpr...
975 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
976 Op1I->setOperand(0, IIOp1);
977 Op1I->setOperand(1, IIOp0);
979 // Create the new top level add instruction...
980 return BinaryOperator::createAdd(Op0, Op1);
983 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
985 if (Op1I->getOpcode() == Instruction::And &&
986 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
987 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
990 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
991 return BinaryOperator::createAnd(Op0, NewNot);
994 // -(X sdiv C) -> (X sdiv -C)
995 if (Op1I->getOpcode() == Instruction::Div)
996 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
997 if (CSI->isNullValue())
998 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
999 return BinaryOperator::createDiv(Op1I->getOperand(0),
1000 ConstantExpr::getNeg(DivRHS));
1002 // X - X*C --> X * (1-C)
1003 ConstantInt *C2 = 0;
1004 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
1006 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
1007 return BinaryOperator::createMul(Op0, CP1);
1012 if (!Op0->getType()->isFloatingPoint())
1013 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
1014 if (Op0I->getOpcode() == Instruction::Add) {
1015 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
1016 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
1017 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
1018 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
1019 } else if (Op0I->getOpcode() == Instruction::Sub) {
1020 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
1021 return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName());
1025 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
1026 if (X == Op1) { // X*C - X --> X * (C-1)
1027 Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
1028 return BinaryOperator::createMul(Op1, CP1);
1031 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
1032 if (X == dyn_castFoldableMul(Op1, C2))
1033 return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
1038 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
1039 /// really just returns true if the most significant (sign) bit is set.
1040 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
1041 if (RHS->getType()->isSigned()) {
1042 // True if source is LHS < 0 or LHS <= -1
1043 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
1044 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
1046 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
1047 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
1048 // the size of the integer type.
1049 if (Opcode == Instruction::SetGE)
1050 return RHSC->getValue() ==
1051 1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1);
1052 if (Opcode == Instruction::SetGT)
1053 return RHSC->getValue() ==
1054 (1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1))-1;
1059 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
1060 bool Changed = SimplifyCommutative(I);
1061 Value *Op0 = I.getOperand(0);
1063 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
1064 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1066 // Simplify mul instructions with a constant RHS...
1067 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
1068 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
1070 // ((X << C1)*C2) == (X * (C2 << C1))
1071 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
1072 if (SI->getOpcode() == Instruction::Shl)
1073 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
1074 return BinaryOperator::createMul(SI->getOperand(0),
1075 ConstantExpr::getShl(CI, ShOp));
1077 if (CI->isNullValue())
1078 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
1079 if (CI->equalsInt(1)) // X * 1 == X
1080 return ReplaceInstUsesWith(I, Op0);
1081 if (CI->isAllOnesValue()) // X * -1 == 0 - X
1082 return BinaryOperator::createNeg(Op0, I.getName());
1084 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
1085 if (isPowerOf2_64(Val)) { // Replace X*(2^C) with X << C
1086 uint64_t C = Log2_64(Val);
1087 return new ShiftInst(Instruction::Shl, Op0,
1088 ConstantUInt::get(Type::UByteTy, C));
1090 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
1091 if (Op1F->isNullValue())
1092 return ReplaceInstUsesWith(I, Op1);
1094 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
1095 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
1096 if (Op1F->getValue() == 1.0)
1097 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
1100 // Try to fold constant mul into select arguments.
1101 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1102 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1105 if (isa<PHINode>(Op0))
1106 if (Instruction *NV = FoldOpIntoPhi(I))
1110 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
1111 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
1112 return BinaryOperator::createMul(Op0v, Op1v);
1114 // If one of the operands of the multiply is a cast from a boolean value, then
1115 // we know the bool is either zero or one, so this is a 'masking' multiply.
1116 // See if we can simplify things based on how the boolean was originally
1118 CastInst *BoolCast = 0;
1119 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
1120 if (CI->getOperand(0)->getType() == Type::BoolTy)
1123 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
1124 if (CI->getOperand(0)->getType() == Type::BoolTy)
1127 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
1128 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
1129 const Type *SCOpTy = SCIOp0->getType();
1131 // If the setcc is true iff the sign bit of X is set, then convert this
1132 // multiply into a shift/and combination.
1133 if (isa<ConstantInt>(SCIOp1) &&
1134 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
1135 // Shift the X value right to turn it into "all signbits".
1136 Constant *Amt = ConstantUInt::get(Type::UByteTy,
1137 SCOpTy->getPrimitiveSizeInBits()-1);
1138 if (SCIOp0->getType()->isUnsigned()) {
1139 const Type *NewTy = SCIOp0->getType()->getSignedVersion();
1140 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
1141 SCIOp0->getName()), I);
1145 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
1146 BoolCast->getOperand(0)->getName()+
1149 // If the multiply type is not the same as the source type, sign extend
1150 // or truncate to the multiply type.
1151 if (I.getType() != V->getType())
1152 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
1154 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
1155 return BinaryOperator::createAnd(V, OtherOp);
1160 return Changed ? &I : 0;
1163 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
1164 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1166 if (isa<UndefValue>(Op0)) // undef / X -> 0
1167 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1168 if (isa<UndefValue>(Op1))
1169 return ReplaceInstUsesWith(I, Op1); // X / undef -> undef
1171 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1173 if (RHS->equalsInt(1))
1174 return ReplaceInstUsesWith(I, Op0);
1177 if (RHS->isAllOnesValue())
1178 return BinaryOperator::createNeg(Op0);
1180 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
1181 if (LHS->getOpcode() == Instruction::Div)
1182 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
1183 // (X / C1) / C2 -> X / (C1*C2)
1184 return BinaryOperator::createDiv(LHS->getOperand(0),
1185 ConstantExpr::getMul(RHS, LHSRHS));
1188 // Check to see if this is an unsigned division with an exact power of 2,
1189 // if so, convert to a right shift.
1190 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1191 if (uint64_t Val = C->getValue()) // Don't break X / 0
1192 if (isPowerOf2_64(Val)) {
1193 uint64_t C = Log2_64(Val);
1194 return new ShiftInst(Instruction::Shr, Op0,
1195 ConstantUInt::get(Type::UByteTy, C));
1199 if (RHS->getType()->isSigned())
1200 if (Value *LHSNeg = dyn_castNegVal(Op0))
1201 return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS));
1203 if (!RHS->isNullValue()) {
1204 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1205 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1207 if (isa<PHINode>(Op0))
1208 if (Instruction *NV = FoldOpIntoPhi(I))
1213 // If this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1214 // transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'.
1215 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1216 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1217 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1218 if (STO->getValue() == 0) { // Couldn't be this argument.
1219 I.setOperand(1, SFO);
1221 } else if (SFO->getValue() == 0) {
1222 I.setOperand(1, STO);
1226 uint64_t TVA = STO->getValue(), FVA = SFO->getValue();
1227 if (isPowerOf2_64(TVA) && isPowerOf2_64(FVA)) {
1228 unsigned TSA = Log2_64(TVA), FSA = Log2_64(FVA);
1229 Constant *TC = ConstantUInt::get(Type::UByteTy, TSA);
1230 Instruction *TSI = new ShiftInst(Instruction::Shr, Op0,
1231 TC, SI->getName()+".t");
1232 TSI = InsertNewInstBefore(TSI, I);
1234 Constant *FC = ConstantUInt::get(Type::UByteTy, FSA);
1235 Instruction *FSI = new ShiftInst(Instruction::Shr, Op0,
1236 FC, SI->getName()+".f");
1237 FSI = InsertNewInstBefore(FSI, I);
1238 return new SelectInst(SI->getOperand(0), TSI, FSI);
1242 // 0 / X == 0, we don't need to preserve faults!
1243 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1244 if (LHS->equalsInt(0))
1245 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1247 if (I.getType()->isSigned()) {
1248 // If the top bits of both operands are zero (i.e. we can prove they are
1249 // unsigned inputs), turn this into a udiv.
1250 ConstantIntegral *MaskV = ConstantSInt::getMinValue(I.getType());
1251 if (MaskedValueIsZero(Op1, MaskV) && MaskedValueIsZero(Op0, MaskV)) {
1252 const Type *NTy = Op0->getType()->getUnsignedVersion();
1253 Instruction *LHS = new CastInst(Op0, NTy, Op0->getName());
1254 InsertNewInstBefore(LHS, I);
1256 if (Constant *R = dyn_cast<Constant>(Op1))
1257 RHS = ConstantExpr::getCast(R, NTy);
1259 RHS = InsertNewInstBefore(new CastInst(Op1, NTy, Op1->getName()), I);
1260 Instruction *Div = BinaryOperator::createDiv(LHS, RHS, I.getName());
1261 InsertNewInstBefore(Div, I);
1262 return new CastInst(Div, I.getType());
1270 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
1271 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1272 if (I.getType()->isSigned()) {
1273 if (Value *RHSNeg = dyn_castNegVal(Op1))
1274 if (!isa<ConstantSInt>(RHSNeg) ||
1275 cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
1277 AddUsesToWorkList(I);
1278 I.setOperand(1, RHSNeg);
1282 // If the top bits of both operands are zero (i.e. we can prove they are
1283 // unsigned inputs), turn this into a urem.
1284 ConstantIntegral *MaskV = ConstantSInt::getMinValue(I.getType());
1285 if (MaskedValueIsZero(Op1, MaskV) && MaskedValueIsZero(Op0, MaskV)) {
1286 const Type *NTy = Op0->getType()->getUnsignedVersion();
1287 Instruction *LHS = new CastInst(Op0, NTy, Op0->getName());
1288 InsertNewInstBefore(LHS, I);
1290 if (Constant *R = dyn_cast<Constant>(Op1))
1291 RHS = ConstantExpr::getCast(R, NTy);
1293 RHS = InsertNewInstBefore(new CastInst(Op1, NTy, Op1->getName()), I);
1294 Instruction *Rem = BinaryOperator::createRem(LHS, RHS, I.getName());
1295 InsertNewInstBefore(Rem, I);
1296 return new CastInst(Rem, I.getType());
1300 if (isa<UndefValue>(Op0)) // undef % X -> 0
1301 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1302 if (isa<UndefValue>(Op1))
1303 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
1305 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1306 if (RHS->equalsInt(1)) // X % 1 == 0
1307 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1309 // Check to see if this is an unsigned remainder with an exact power of 2,
1310 // if so, convert to a bitwise and.
1311 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1312 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
1313 if (!(Val & (Val-1))) // Power of 2
1314 return BinaryOperator::createAnd(Op0,
1315 ConstantUInt::get(I.getType(), Val-1));
1317 if (!RHS->isNullValue()) {
1318 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1319 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1321 if (isa<PHINode>(Op0))
1322 if (Instruction *NV = FoldOpIntoPhi(I))
1327 // If this is 'urem X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1328 // transform this into: '(Cond ? (urem X, C1) : (urem X, C2))'.
1329 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1330 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1331 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1332 if (STO->getValue() == 0) { // Couldn't be this argument.
1333 I.setOperand(1, SFO);
1335 } else if (SFO->getValue() == 0) {
1336 I.setOperand(1, STO);
1340 if (!(STO->getValue() & (STO->getValue()-1)) &&
1341 !(SFO->getValue() & (SFO->getValue()-1))) {
1342 Value *TrueAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1343 SubOne(STO), SI->getName()+".t"), I);
1344 Value *FalseAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1345 SubOne(SFO), SI->getName()+".f"), I);
1346 return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
1350 // 0 % X == 0, we don't need to preserve faults!
1351 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1352 if (LHS->equalsInt(0))
1353 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1358 // isMaxValueMinusOne - return true if this is Max-1
1359 static bool isMaxValueMinusOne(const ConstantInt *C) {
1360 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
1361 // Calculate -1 casted to the right type...
1362 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1363 uint64_t Val = ~0ULL; // All ones
1364 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1365 return CU->getValue() == Val-1;
1368 const ConstantSInt *CS = cast<ConstantSInt>(C);
1370 // Calculate 0111111111..11111
1371 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1372 int64_t Val = INT64_MAX; // All ones
1373 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1374 return CS->getValue() == Val-1;
1377 // isMinValuePlusOne - return true if this is Min+1
1378 static bool isMinValuePlusOne(const ConstantInt *C) {
1379 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1380 return CU->getValue() == 1;
1382 const ConstantSInt *CS = cast<ConstantSInt>(C);
1384 // Calculate 1111111111000000000000
1385 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1386 int64_t Val = -1; // All ones
1387 Val <<= TypeBits-1; // Shift over to the right spot
1388 return CS->getValue() == Val+1;
1391 // isOneBitSet - Return true if there is exactly one bit set in the specified
1393 static bool isOneBitSet(const ConstantInt *CI) {
1394 uint64_t V = CI->getRawValue();
1395 return V && (V & (V-1)) == 0;
1398 #if 0 // Currently unused
1399 // isLowOnes - Return true if the constant is of the form 0+1+.
1400 static bool isLowOnes(const ConstantInt *CI) {
1401 uint64_t V = CI->getRawValue();
1403 // There won't be bits set in parts that the type doesn't contain.
1404 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1406 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1407 return U && V && (U & V) == 0;
1411 // isHighOnes - Return true if the constant is of the form 1+0+.
1412 // This is the same as lowones(~X).
1413 static bool isHighOnes(const ConstantInt *CI) {
1414 uint64_t V = ~CI->getRawValue();
1415 if (~V == 0) return false; // 0's does not match "1+"
1417 // There won't be bits set in parts that the type doesn't contain.
1418 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1420 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1421 return U && V && (U & V) == 0;
1425 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
1426 /// are carefully arranged to allow folding of expressions such as:
1428 /// (A < B) | (A > B) --> (A != B)
1430 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
1431 /// represents that the comparison is true if A == B, and bit value '1' is true
1434 static unsigned getSetCondCode(const SetCondInst *SCI) {
1435 switch (SCI->getOpcode()) {
1437 case Instruction::SetGT: return 1;
1438 case Instruction::SetEQ: return 2;
1439 case Instruction::SetGE: return 3;
1440 case Instruction::SetLT: return 4;
1441 case Instruction::SetNE: return 5;
1442 case Instruction::SetLE: return 6;
1445 assert(0 && "Invalid SetCC opcode!");
1450 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
1451 /// opcode and two operands into either a constant true or false, or a brand new
1452 /// SetCC instruction.
1453 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
1455 case 0: return ConstantBool::False;
1456 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
1457 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
1458 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
1459 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
1460 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
1461 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
1462 case 7: return ConstantBool::True;
1463 default: assert(0 && "Illegal SetCCCode!"); return 0;
1467 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1468 struct FoldSetCCLogical {
1471 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
1472 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
1473 bool shouldApply(Value *V) const {
1474 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
1475 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
1476 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
1479 Instruction *apply(BinaryOperator &Log) const {
1480 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
1481 if (SCI->getOperand(0) != LHS) {
1482 assert(SCI->getOperand(1) == LHS);
1483 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
1486 unsigned LHSCode = getSetCondCode(SCI);
1487 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
1489 switch (Log.getOpcode()) {
1490 case Instruction::And: Code = LHSCode & RHSCode; break;
1491 case Instruction::Or: Code = LHSCode | RHSCode; break;
1492 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
1493 default: assert(0 && "Illegal logical opcode!"); return 0;
1496 Value *RV = getSetCCValue(Code, LHS, RHS);
1497 if (Instruction *I = dyn_cast<Instruction>(RV))
1499 // Otherwise, it's a constant boolean value...
1500 return IC.ReplaceInstUsesWith(Log, RV);
1504 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
1505 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
1506 // guaranteed to be either a shift instruction or a binary operator.
1507 Instruction *InstCombiner::OptAndOp(Instruction *Op,
1508 ConstantIntegral *OpRHS,
1509 ConstantIntegral *AndRHS,
1510 BinaryOperator &TheAnd) {
1511 Value *X = Op->getOperand(0);
1512 Constant *Together = 0;
1513 if (!isa<ShiftInst>(Op))
1514 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
1516 switch (Op->getOpcode()) {
1517 case Instruction::Xor:
1518 if (Op->hasOneUse()) {
1519 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
1520 std::string OpName = Op->getName(); Op->setName("");
1521 Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
1522 InsertNewInstBefore(And, TheAnd);
1523 return BinaryOperator::createXor(And, Together);
1526 case Instruction::Or:
1527 if (Together == AndRHS) // (X | C) & C --> C
1528 return ReplaceInstUsesWith(TheAnd, AndRHS);
1530 if (Op->hasOneUse() && Together != OpRHS) {
1531 // (X | C1) & C2 --> (X | (C1&C2)) & C2
1532 std::string Op0Name = Op->getName(); Op->setName("");
1533 Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
1534 InsertNewInstBefore(Or, TheAnd);
1535 return BinaryOperator::createAnd(Or, AndRHS);
1538 case Instruction::Add:
1539 if (Op->hasOneUse()) {
1540 // Adding a one to a single bit bit-field should be turned into an XOR
1541 // of the bit. First thing to check is to see if this AND is with a
1542 // single bit constant.
1543 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
1545 // Clear bits that are not part of the constant.
1546 AndRHSV &= ~0ULL >> (64-AndRHS->getType()->getPrimitiveSizeInBits());
1548 // If there is only one bit set...
1549 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
1550 // Ok, at this point, we know that we are masking the result of the
1551 // ADD down to exactly one bit. If the constant we are adding has
1552 // no bits set below this bit, then we can eliminate the ADD.
1553 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
1555 // Check to see if any bits below the one bit set in AndRHSV are set.
1556 if ((AddRHS & (AndRHSV-1)) == 0) {
1557 // If not, the only thing that can effect the output of the AND is
1558 // the bit specified by AndRHSV. If that bit is set, the effect of
1559 // the XOR is to toggle the bit. If it is clear, then the ADD has
1561 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
1562 TheAnd.setOperand(0, X);
1565 std::string Name = Op->getName(); Op->setName("");
1566 // Pull the XOR out of the AND.
1567 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
1568 InsertNewInstBefore(NewAnd, TheAnd);
1569 return BinaryOperator::createXor(NewAnd, AndRHS);
1576 case Instruction::Shl: {
1577 // We know that the AND will not produce any of the bits shifted in, so if
1578 // the anded constant includes them, clear them now!
1580 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1581 Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
1582 Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
1584 if (CI == ShlMask) { // Masking out bits that the shift already masks
1585 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
1586 } else if (CI != AndRHS) { // Reducing bits set in and.
1587 TheAnd.setOperand(1, CI);
1592 case Instruction::Shr:
1593 // We know that the AND will not produce any of the bits shifted in, so if
1594 // the anded constant includes them, clear them now! This only applies to
1595 // unsigned shifts, because a signed shr may bring in set bits!
1597 if (AndRHS->getType()->isUnsigned()) {
1598 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1599 Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS);
1600 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1602 if (CI == ShrMask) { // Masking out bits that the shift already masks.
1603 return ReplaceInstUsesWith(TheAnd, Op);
1604 } else if (CI != AndRHS) {
1605 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
1608 } else { // Signed shr.
1609 // See if this is shifting in some sign extension, then masking it out
1611 if (Op->hasOneUse()) {
1612 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1613 Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS);
1614 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1615 if (CI == AndRHS) { // Masking out bits shifted in.
1616 // Make the argument unsigned.
1617 Value *ShVal = Op->getOperand(0);
1618 ShVal = InsertCastBefore(ShVal,
1619 ShVal->getType()->getUnsignedVersion(),
1621 ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal,
1622 OpRHS, Op->getName()),
1624 Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType());
1625 ShVal = InsertNewInstBefore(BinaryOperator::createAnd(ShVal, AndRHS2,
1628 return new CastInst(ShVal, Op->getType());
1638 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
1639 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
1640 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. IB is the location to
1641 /// insert new instructions.
1642 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
1643 bool Inside, Instruction &IB) {
1644 assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
1645 "Lo is not <= Hi in range emission code!");
1647 if (Lo == Hi) // Trivially false.
1648 return new SetCondInst(Instruction::SetNE, V, V);
1649 if (cast<ConstantIntegral>(Lo)->isMinValue())
1650 return new SetCondInst(Instruction::SetLT, V, Hi);
1652 Constant *AddCST = ConstantExpr::getNeg(Lo);
1653 Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
1654 InsertNewInstBefore(Add, IB);
1655 // Convert to unsigned for the comparison.
1656 const Type *UnsType = Add->getType()->getUnsignedVersion();
1657 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1658 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1659 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1660 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1663 if (Lo == Hi) // Trivially true.
1664 return new SetCondInst(Instruction::SetEQ, V, V);
1666 Hi = SubOne(cast<ConstantInt>(Hi));
1667 if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
1668 return new SetCondInst(Instruction::SetGT, V, Hi);
1670 // Emit X-Lo > Hi-Lo-1
1671 Constant *AddCST = ConstantExpr::getNeg(Lo);
1672 Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
1673 InsertNewInstBefore(Add, IB);
1674 // Convert to unsigned for the comparison.
1675 const Type *UnsType = Add->getType()->getUnsignedVersion();
1676 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1677 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1678 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1679 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1682 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
1683 // any number of 0s on either side. The 1s are allowed to wrap from LSB to
1684 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
1685 // not, since all 1s are not contiguous.
1686 static bool isRunOfOnes(ConstantIntegral *Val, unsigned &MB, unsigned &ME) {
1687 uint64_t V = Val->getRawValue();
1688 if (!isShiftedMask_64(V)) return false;
1690 // look for the first zero bit after the run of ones
1691 MB = 64-CountLeadingZeros_64((V - 1) ^ V);
1692 // look for the first non-zero bit
1693 ME = 64-CountLeadingZeros_64(V);
1699 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
1700 /// where isSub determines whether the operator is a sub. If we can fold one of
1701 /// the following xforms:
1703 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
1704 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
1705 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
1707 /// return (A +/- B).
1709 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
1710 ConstantIntegral *Mask, bool isSub,
1712 Instruction *LHSI = dyn_cast<Instruction>(LHS);
1713 if (!LHSI || LHSI->getNumOperands() != 2 ||
1714 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
1716 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
1718 switch (LHSI->getOpcode()) {
1720 case Instruction::And:
1721 if (ConstantExpr::getAnd(N, Mask) == Mask) {
1722 // If the AndRHS is a power of two minus one (0+1+), this is simple.
1723 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0)
1726 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
1727 // part, we don't need any explicit masks to take them out of A. If that
1728 // is all N is, ignore it.
1730 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
1731 Constant *Mask = ConstantInt::getAllOnesValue(RHS->getType());
1732 Mask = ConstantExpr::getUShr(Mask,
1733 ConstantInt::get(Type::UByteTy,
1735 if (MaskedValueIsZero(RHS, cast<ConstantIntegral>(Mask)))
1740 case Instruction::Or:
1741 case Instruction::Xor:
1742 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
1743 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0 &&
1744 ConstantExpr::getAnd(N, Mask)->isNullValue())
1751 New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold");
1753 New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold");
1754 return InsertNewInstBefore(New, I);
1757 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1758 bool Changed = SimplifyCommutative(I);
1759 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1761 if (isa<UndefValue>(Op1)) // X & undef -> 0
1762 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1766 return ReplaceInstUsesWith(I, Op1);
1768 if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) {
1770 if (AndRHS->isAllOnesValue())
1771 return ReplaceInstUsesWith(I, Op0);
1773 // and (and X, c1), c2 -> and (x, c1&c2). Handle this case here, before
1774 // calling MaskedValueIsZero, to avoid inefficient cases where we traipse
1775 // through many levels of ands.
1777 Value *X = 0; ConstantInt *C1 = 0;
1778 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))))
1779 return BinaryOperator::createAnd(X, ConstantExpr::getAnd(C1, AndRHS));
1782 if (MaskedValueIsZero(Op0, AndRHS)) // LHS & RHS == 0
1783 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1785 // If the mask is not masking out any bits, there is no reason to do the
1786 // and in the first place.
1787 ConstantIntegral *NotAndRHS =
1788 cast<ConstantIntegral>(ConstantExpr::getNot(AndRHS));
1789 if (MaskedValueIsZero(Op0, NotAndRHS))
1790 return ReplaceInstUsesWith(I, Op0);
1792 // Optimize a variety of ((val OP C1) & C2) combinations...
1793 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
1794 Instruction *Op0I = cast<Instruction>(Op0);
1795 Value *Op0LHS = Op0I->getOperand(0);
1796 Value *Op0RHS = Op0I->getOperand(1);
1797 switch (Op0I->getOpcode()) {
1798 case Instruction::Xor:
1799 case Instruction::Or:
1800 // (X ^ V) & C2 --> (X & C2) iff (V & C2) == 0
1801 // (X | V) & C2 --> (X & C2) iff (V & C2) == 0
1802 if (MaskedValueIsZero(Op0LHS, AndRHS))
1803 return BinaryOperator::createAnd(Op0RHS, AndRHS);
1804 if (MaskedValueIsZero(Op0RHS, AndRHS))
1805 return BinaryOperator::createAnd(Op0LHS, AndRHS);
1807 // If the mask is only needed on one incoming arm, push it up.
1808 if (Op0I->hasOneUse()) {
1809 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
1810 // Not masking anything out for the LHS, move to RHS.
1811 Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
1812 Op0RHS->getName()+".masked");
1813 InsertNewInstBefore(NewRHS, I);
1814 return BinaryOperator::create(
1815 cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
1817 if (!isa<Constant>(NotAndRHS) &&
1818 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
1819 // Not masking anything out for the RHS, move to LHS.
1820 Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
1821 Op0LHS->getName()+".masked");
1822 InsertNewInstBefore(NewLHS, I);
1823 return BinaryOperator::create(
1824 cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
1829 case Instruction::And:
1830 // (X & V) & C2 --> 0 iff (V & C2) == 0
1831 if (MaskedValueIsZero(Op0LHS, AndRHS) ||
1832 MaskedValueIsZero(Op0RHS, AndRHS))
1833 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1835 case Instruction::Add:
1836 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
1837 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1838 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1839 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
1840 return BinaryOperator::createAnd(V, AndRHS);
1841 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
1842 return BinaryOperator::createAnd(V, AndRHS); // Add commutes
1845 case Instruction::Sub:
1846 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
1847 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1848 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1849 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
1850 return BinaryOperator::createAnd(V, AndRHS);
1854 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1855 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
1857 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
1858 const Type *SrcTy = CI->getOperand(0)->getType();
1860 // If this is an integer truncation or change from signed-to-unsigned, and
1861 // if the source is an and/or with immediate, transform it. This
1862 // frequently occurs for bitfield accesses.
1863 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
1864 if (SrcTy->getPrimitiveSizeInBits() >=
1865 I.getType()->getPrimitiveSizeInBits() &&
1866 CastOp->getNumOperands() == 2)
1867 if (ConstantInt *AndCI =dyn_cast<ConstantInt>(CastOp->getOperand(1)))
1868 if (CastOp->getOpcode() == Instruction::And) {
1869 // Change: and (cast (and X, C1) to T), C2
1870 // into : and (cast X to T), trunc(C1)&C2
1871 // This will folds the two ands together, which may allow other
1873 Instruction *NewCast =
1874 new CastInst(CastOp->getOperand(0), I.getType(),
1875 CastOp->getName()+".shrunk");
1876 NewCast = InsertNewInstBefore(NewCast, I);
1878 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1879 C3 = ConstantExpr::getAnd(C3, AndRHS); // trunc(C1)&C2
1880 return BinaryOperator::createAnd(NewCast, C3);
1881 } else if (CastOp->getOpcode() == Instruction::Or) {
1882 // Change: and (cast (or X, C1) to T), C2
1883 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
1884 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1885 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
1886 return ReplaceInstUsesWith(I, AndRHS);
1891 // If this is an integer sign or zero extension instruction.
1892 if (SrcTy->isIntegral() &&
1893 SrcTy->getPrimitiveSizeInBits() <
1894 CI->getType()->getPrimitiveSizeInBits()) {
1896 if (SrcTy->isUnsigned()) {
1897 // See if this and is clearing out bits that are known to be zero
1898 // anyway (due to the zero extension).
1899 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1900 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1901 Constant *Result = ConstantExpr::getAnd(Mask, AndRHS);
1902 if (Result == Mask) // The "and" isn't doing anything, remove it.
1903 return ReplaceInstUsesWith(I, CI);
1904 if (Result != AndRHS) { // Reduce the and RHS constant.
1905 I.setOperand(1, Result);
1910 if (CI->hasOneUse() && SrcTy->isInteger()) {
1911 // We can only do this if all of the sign bits brought in are masked
1912 // out. Compute this by first getting 0000011111, then inverting
1914 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1915 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1916 Mask = ConstantExpr::getNot(Mask); // 1's in the new bits.
1917 if (ConstantExpr::getAnd(Mask, AndRHS)->isNullValue()) {
1918 // If the and is clearing all of the sign bits, change this to a
1919 // zero extension cast. To do this, cast the cast input to
1920 // unsigned, then to the requested size.
1921 Value *CastOp = CI->getOperand(0);
1923 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
1924 CI->getName()+".uns");
1925 NC = InsertNewInstBefore(NC, I);
1926 // Finally, insert a replacement for CI.
1927 NC = new CastInst(NC, CI->getType(), CI->getName());
1929 NC = InsertNewInstBefore(NC, I);
1930 WorkList.push_back(CI); // Delete CI later.
1931 I.setOperand(0, NC);
1932 return &I; // The AND operand was modified.
1939 // Try to fold constant and into select arguments.
1940 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1941 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1943 if (isa<PHINode>(Op0))
1944 if (Instruction *NV = FoldOpIntoPhi(I))
1948 Value *Op0NotVal = dyn_castNotVal(Op0);
1949 Value *Op1NotVal = dyn_castNotVal(Op1);
1951 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1952 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1954 // (~A & ~B) == (~(A | B)) - De Morgan's Law
1955 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1956 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
1957 I.getName()+".demorgan");
1958 InsertNewInstBefore(Or, I);
1959 return BinaryOperator::createNot(Or);
1962 if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
1963 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1964 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1967 Value *LHSVal, *RHSVal;
1968 ConstantInt *LHSCst, *RHSCst;
1969 Instruction::BinaryOps LHSCC, RHSCC;
1970 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1971 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1972 if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
1973 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1974 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1975 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1976 // Ensure that the larger constant is on the RHS.
1977 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1978 SetCondInst *LHS = cast<SetCondInst>(Op0);
1979 if (cast<ConstantBool>(Cmp)->getValue()) {
1980 std::swap(LHS, RHS);
1981 std::swap(LHSCst, RHSCst);
1982 std::swap(LHSCC, RHSCC);
1985 // At this point, we know we have have two setcc instructions
1986 // comparing a value against two constants and and'ing the result
1987 // together. Because of the above check, we know that we only have
1988 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1989 // FoldSetCCLogical check above), that the two constants are not
1991 assert(LHSCst != RHSCst && "Compares not folded above?");
1994 default: assert(0 && "Unknown integer condition code!");
1995 case Instruction::SetEQ:
1997 default: assert(0 && "Unknown integer condition code!");
1998 case Instruction::SetEQ: // (X == 13 & X == 15) -> false
1999 case Instruction::SetGT: // (X == 13 & X > 15) -> false
2000 return ReplaceInstUsesWith(I, ConstantBool::False);
2001 case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
2002 case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
2003 return ReplaceInstUsesWith(I, LHS);
2005 case Instruction::SetNE:
2007 default: assert(0 && "Unknown integer condition code!");
2008 case Instruction::SetLT:
2009 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
2010 return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
2011 break; // (X != 13 & X < 15) -> no change
2012 case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
2013 case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
2014 return ReplaceInstUsesWith(I, RHS);
2015 case Instruction::SetNE:
2016 if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
2017 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2018 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
2019 LHSVal->getName()+".off");
2020 InsertNewInstBefore(Add, I);
2021 const Type *UnsType = Add->getType()->getUnsignedVersion();
2022 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
2023 AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
2024 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2025 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
2027 break; // (X != 13 & X != 15) -> no change
2030 case Instruction::SetLT:
2032 default: assert(0 && "Unknown integer condition code!");
2033 case Instruction::SetEQ: // (X < 13 & X == 15) -> false
2034 case Instruction::SetGT: // (X < 13 & X > 15) -> false
2035 return ReplaceInstUsesWith(I, ConstantBool::False);
2036 case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
2037 case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
2038 return ReplaceInstUsesWith(I, LHS);
2040 case Instruction::SetGT:
2042 default: assert(0 && "Unknown integer condition code!");
2043 case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
2044 return ReplaceInstUsesWith(I, LHS);
2045 case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
2046 return ReplaceInstUsesWith(I, RHS);
2047 case Instruction::SetNE:
2048 if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
2049 return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
2050 break; // (X > 13 & X != 15) -> no change
2051 case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
2052 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
2058 return Changed ? &I : 0;
2061 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
2062 bool Changed = SimplifyCommutative(I);
2063 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2065 if (isa<UndefValue>(Op1))
2066 return ReplaceInstUsesWith(I, // X | undef -> -1
2067 ConstantIntegral::getAllOnesValue(I.getType()));
2069 // or X, X = X or X, 0 == X
2070 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
2071 return ReplaceInstUsesWith(I, Op0);
2074 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2075 // If X is known to only contain bits that already exist in RHS, just
2076 // replace this instruction with RHS directly.
2077 if (MaskedValueIsZero(Op0,
2078 cast<ConstantIntegral>(ConstantExpr::getNot(RHS))))
2079 return ReplaceInstUsesWith(I, RHS);
2081 ConstantInt *C1 = 0; Value *X = 0;
2082 // (X & C1) | C2 --> (X | C2) & (C1|C2)
2083 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
2084 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0->getName());
2086 InsertNewInstBefore(Or, I);
2087 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
2090 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
2091 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
2092 std::string Op0Name = Op0->getName(); Op0->setName("");
2093 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
2094 InsertNewInstBefore(Or, I);
2095 return BinaryOperator::createXor(Or,
2096 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
2099 // Try to fold constant and into select arguments.
2100 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2101 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2103 if (isa<PHINode>(Op0))
2104 if (Instruction *NV = FoldOpIntoPhi(I))
2108 Value *A = 0, *B = 0;
2109 ConstantInt *C1 = 0, *C2 = 0;
2111 if (match(Op0, m_And(m_Value(A), m_Value(B))))
2112 if (A == Op1 || B == Op1) // (A & ?) | A --> A
2113 return ReplaceInstUsesWith(I, Op1);
2114 if (match(Op1, m_And(m_Value(A), m_Value(B))))
2115 if (A == Op0 || B == Op0) // A | (A & ?) --> A
2116 return ReplaceInstUsesWith(I, Op0);
2118 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
2119 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2120 MaskedValueIsZero(Op1, C1)) {
2121 Instruction *NOr = BinaryOperator::createOr(A, Op1, Op0->getName());
2123 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2126 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
2127 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2128 MaskedValueIsZero(Op0, C1)) {
2129 Instruction *NOr = BinaryOperator::createOr(A, Op0, Op1->getName());
2131 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2134 // (A & C1)|(B & C2)
2135 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2136 match(Op1, m_And(m_Value(B), m_ConstantInt(C2)))) {
2138 if (A == B) // (A & C1)|(A & C2) == A & (C1|C2)
2139 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
2142 // If we have: ((V + N) & C1) | (V & C2)
2143 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
2144 // replace with V+N.
2145 if (C1 == ConstantExpr::getNot(C2)) {
2146 Value *V1 = 0, *V2 = 0;
2147 if ((C2->getRawValue() & (C2->getRawValue()+1)) == 0 && // C2 == 0+1+
2148 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
2149 // Add commutes, try both ways.
2150 if (V1 == B && MaskedValueIsZero(V2, C2))
2151 return ReplaceInstUsesWith(I, A);
2152 if (V2 == B && MaskedValueIsZero(V1, C2))
2153 return ReplaceInstUsesWith(I, A);
2155 // Or commutes, try both ways.
2156 if ((C1->getRawValue() & (C1->getRawValue()+1)) == 0 &&
2157 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
2158 // Add commutes, try both ways.
2159 if (V1 == A && MaskedValueIsZero(V2, C1))
2160 return ReplaceInstUsesWith(I, B);
2161 if (V2 == A && MaskedValueIsZero(V1, C1))
2162 return ReplaceInstUsesWith(I, B);
2167 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
2168 if (A == Op1) // ~A | A == -1
2169 return ReplaceInstUsesWith(I,
2170 ConstantIntegral::getAllOnesValue(I.getType()));
2174 // Note, A is still live here!
2175 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
2177 return ReplaceInstUsesWith(I,
2178 ConstantIntegral::getAllOnesValue(I.getType()));
2180 // (~A | ~B) == (~(A & B)) - De Morgan's Law
2181 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
2182 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
2183 I.getName()+".demorgan"), I);
2184 return BinaryOperator::createNot(And);
2188 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
2189 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
2190 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2193 Value *LHSVal, *RHSVal;
2194 ConstantInt *LHSCst, *RHSCst;
2195 Instruction::BinaryOps LHSCC, RHSCC;
2196 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
2197 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
2198 if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
2199 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
2200 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
2201 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
2202 // Ensure that the larger constant is on the RHS.
2203 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
2204 SetCondInst *LHS = cast<SetCondInst>(Op0);
2205 if (cast<ConstantBool>(Cmp)->getValue()) {
2206 std::swap(LHS, RHS);
2207 std::swap(LHSCst, RHSCst);
2208 std::swap(LHSCC, RHSCC);
2211 // At this point, we know we have have two setcc instructions
2212 // comparing a value against two constants and or'ing the result
2213 // together. Because of the above check, we know that we only have
2214 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
2215 // FoldSetCCLogical check above), that the two constants are not
2217 assert(LHSCst != RHSCst && "Compares not folded above?");
2220 default: assert(0 && "Unknown integer condition code!");
2221 case Instruction::SetEQ:
2223 default: assert(0 && "Unknown integer condition code!");
2224 case Instruction::SetEQ:
2225 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
2226 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2227 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
2228 LHSVal->getName()+".off");
2229 InsertNewInstBefore(Add, I);
2230 const Type *UnsType = Add->getType()->getUnsignedVersion();
2231 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
2232 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
2233 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2234 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
2236 break; // (X == 13 | X == 15) -> no change
2238 case Instruction::SetGT: // (X == 13 | X > 14) -> no change
2240 case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
2241 case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
2242 return ReplaceInstUsesWith(I, RHS);
2245 case Instruction::SetNE:
2247 default: assert(0 && "Unknown integer condition code!");
2248 case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
2249 case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
2250 return ReplaceInstUsesWith(I, LHS);
2251 case Instruction::SetNE: // (X != 13 | X != 15) -> true
2252 case Instruction::SetLT: // (X != 13 | X < 15) -> true
2253 return ReplaceInstUsesWith(I, ConstantBool::True);
2256 case Instruction::SetLT:
2258 default: assert(0 && "Unknown integer condition code!");
2259 case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
2261 case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
2262 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
2263 case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
2264 case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
2265 return ReplaceInstUsesWith(I, RHS);
2268 case Instruction::SetGT:
2270 default: assert(0 && "Unknown integer condition code!");
2271 case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
2272 case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
2273 return ReplaceInstUsesWith(I, LHS);
2274 case Instruction::SetNE: // (X > 13 | X != 15) -> true
2275 case Instruction::SetLT: // (X > 13 | X < 15) -> true
2276 return ReplaceInstUsesWith(I, ConstantBool::True);
2282 return Changed ? &I : 0;
2285 // XorSelf - Implements: X ^ X --> 0
2288 XorSelf(Value *rhs) : RHS(rhs) {}
2289 bool shouldApply(Value *LHS) const { return LHS == RHS; }
2290 Instruction *apply(BinaryOperator &Xor) const {
2296 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
2297 bool Changed = SimplifyCommutative(I);
2298 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2300 if (isa<UndefValue>(Op1))
2301 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
2303 // xor X, X = 0, even if X is nested in a sequence of Xor's.
2304 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
2305 assert(Result == &I && "AssociativeOpt didn't work?");
2306 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2309 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2311 if (RHS->isNullValue())
2312 return ReplaceInstUsesWith(I, Op0);
2314 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2315 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
2316 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
2317 if (RHS == ConstantBool::True && SCI->hasOneUse())
2318 return new SetCondInst(SCI->getInverseCondition(),
2319 SCI->getOperand(0), SCI->getOperand(1));
2321 // ~(c-X) == X-c-1 == X+(-c-1)
2322 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
2323 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
2324 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
2325 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
2326 ConstantInt::get(I.getType(), 1));
2327 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
2330 // ~(~X & Y) --> (X | ~Y)
2331 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
2332 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
2333 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
2335 BinaryOperator::createNot(Op0I->getOperand(1),
2336 Op0I->getOperand(1)->getName()+".not");
2337 InsertNewInstBefore(NotY, I);
2338 return BinaryOperator::createOr(Op0NotVal, NotY);
2342 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
2343 switch (Op0I->getOpcode()) {
2344 case Instruction::Add:
2345 // ~(X-c) --> (-c-1)-X
2346 if (RHS->isAllOnesValue()) {
2347 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
2348 return BinaryOperator::createSub(
2349 ConstantExpr::getSub(NegOp0CI,
2350 ConstantInt::get(I.getType(), 1)),
2351 Op0I->getOperand(0));
2354 case Instruction::And:
2355 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
2356 if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue())
2357 return BinaryOperator::createOr(Op0, RHS);
2359 case Instruction::Or:
2360 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
2361 if (ConstantExpr::getAnd(RHS, Op0CI) == RHS)
2362 return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS));
2368 // Try to fold constant and into select arguments.
2369 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2370 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2372 if (isa<PHINode>(Op0))
2373 if (Instruction *NV = FoldOpIntoPhi(I))
2377 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
2379 return ReplaceInstUsesWith(I,
2380 ConstantIntegral::getAllOnesValue(I.getType()));
2382 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
2384 return ReplaceInstUsesWith(I,
2385 ConstantIntegral::getAllOnesValue(I.getType()));
2387 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
2388 if (Op1I->getOpcode() == Instruction::Or) {
2389 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
2390 cast<BinaryOperator>(Op1I)->swapOperands();
2392 std::swap(Op0, Op1);
2393 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
2395 std::swap(Op0, Op1);
2397 } else if (Op1I->getOpcode() == Instruction::Xor) {
2398 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
2399 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
2400 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
2401 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
2404 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
2405 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
2406 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
2407 cast<BinaryOperator>(Op0I)->swapOperands();
2408 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
2409 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
2410 Op1->getName()+".not"), I);
2411 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
2413 } else if (Op0I->getOpcode() == Instruction::Xor) {
2414 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
2415 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2416 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
2417 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2420 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
2421 ConstantInt *C1 = 0, *C2 = 0;
2422 if (match(Op0, m_And(m_Value(), m_ConstantInt(C1))) &&
2423 match(Op1, m_And(m_Value(), m_ConstantInt(C2))) &&
2424 ConstantExpr::getAnd(C1, C2)->isNullValue())
2425 return BinaryOperator::createOr(Op0, Op1);
2427 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
2428 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
2429 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2432 return Changed ? &I : 0;
2435 /// MulWithOverflow - Compute Result = In1*In2, returning true if the result
2436 /// overflowed for this type.
2437 static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2439 Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
2440 return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
2443 static bool isPositive(ConstantInt *C) {
2444 return cast<ConstantSInt>(C)->getValue() >= 0;
2447 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
2448 /// overflowed for this type.
2449 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2451 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
2453 if (In1->getType()->isUnsigned())
2454 return cast<ConstantUInt>(Result)->getValue() <
2455 cast<ConstantUInt>(In1)->getValue();
2456 if (isPositive(In1) != isPositive(In2))
2458 if (isPositive(In1))
2459 return cast<ConstantSInt>(Result)->getValue() <
2460 cast<ConstantSInt>(In1)->getValue();
2461 return cast<ConstantSInt>(Result)->getValue() >
2462 cast<ConstantSInt>(In1)->getValue();
2465 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
2466 /// code necessary to compute the offset from the base pointer (without adding
2467 /// in the base pointer). Return the result as a signed integer of intptr size.
2468 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
2469 TargetData &TD = IC.getTargetData();
2470 gep_type_iterator GTI = gep_type_begin(GEP);
2471 const Type *UIntPtrTy = TD.getIntPtrType();
2472 const Type *SIntPtrTy = UIntPtrTy->getSignedVersion();
2473 Value *Result = Constant::getNullValue(SIntPtrTy);
2475 // Build a mask for high order bits.
2476 uint64_t PtrSizeMask = ~0ULL;
2477 PtrSizeMask >>= 64-(TD.getPointerSize()*8);
2479 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
2480 Value *Op = GEP->getOperand(i);
2481 uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask;
2482 Constant *Scale = ConstantExpr::getCast(ConstantUInt::get(UIntPtrTy, Size),
2484 if (Constant *OpC = dyn_cast<Constant>(Op)) {
2485 if (!OpC->isNullValue()) {
2486 OpC = ConstantExpr::getCast(OpC, SIntPtrTy);
2487 Scale = ConstantExpr::getMul(OpC, Scale);
2488 if (Constant *RC = dyn_cast<Constant>(Result))
2489 Result = ConstantExpr::getAdd(RC, Scale);
2491 // Emit an add instruction.
2492 Result = IC.InsertNewInstBefore(
2493 BinaryOperator::createAdd(Result, Scale,
2494 GEP->getName()+".offs"), I);
2498 // Convert to correct type.
2499 Op = IC.InsertNewInstBefore(new CastInst(Op, SIntPtrTy,
2500 Op->getName()+".c"), I);
2502 // We'll let instcombine(mul) convert this to a shl if possible.
2503 Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
2504 GEP->getName()+".idx"), I);
2506 // Emit an add instruction.
2507 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
2508 GEP->getName()+".offs"), I);
2514 /// FoldGEPSetCC - Fold comparisons between a GEP instruction and something
2515 /// else. At this point we know that the GEP is on the LHS of the comparison.
2516 Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS,
2517 Instruction::BinaryOps Cond,
2519 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
2521 if (CastInst *CI = dyn_cast<CastInst>(RHS))
2522 if (isa<PointerType>(CI->getOperand(0)->getType()))
2523 RHS = CI->getOperand(0);
2525 Value *PtrBase = GEPLHS->getOperand(0);
2526 if (PtrBase == RHS) {
2527 // As an optimization, we don't actually have to compute the actual value of
2528 // OFFSET if this is a seteq or setne comparison, just return whether each
2529 // index is zero or not.
2530 if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) {
2531 Instruction *InVal = 0;
2532 gep_type_iterator GTI = gep_type_begin(GEPLHS);
2533 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
2535 if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
2536 if (isa<UndefValue>(C)) // undef index -> undef.
2537 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
2538 if (C->isNullValue())
2540 else if (TD->getTypeSize(GTI.getIndexedType()) == 0) {
2541 EmitIt = false; // This is indexing into a zero sized array?
2542 } else if (isa<ConstantInt>(C))
2543 return ReplaceInstUsesWith(I, // No comparison is needed here.
2544 ConstantBool::get(Cond == Instruction::SetNE));
2549 new SetCondInst(Cond, GEPLHS->getOperand(i),
2550 Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
2554 InVal = InsertNewInstBefore(InVal, I);
2555 InsertNewInstBefore(Comp, I);
2556 if (Cond == Instruction::SetNE) // True if any are unequal
2557 InVal = BinaryOperator::createOr(InVal, Comp);
2558 else // True if all are equal
2559 InVal = BinaryOperator::createAnd(InVal, Comp);
2567 ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0
2568 ConstantBool::get(Cond == Instruction::SetEQ));
2571 // Only lower this if the setcc is the only user of the GEP or if we expect
2572 // the result to fold to a constant!
2573 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
2574 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
2575 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
2576 return new SetCondInst(Cond, Offset,
2577 Constant::getNullValue(Offset->getType()));
2579 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
2580 // If the base pointers are different, but the indices are the same, just
2581 // compare the base pointer.
2582 if (PtrBase != GEPRHS->getOperand(0)) {
2583 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
2584 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
2585 GEPRHS->getOperand(0)->getType();
2587 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2588 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2589 IndicesTheSame = false;
2593 // If all indices are the same, just compare the base pointers.
2595 return new SetCondInst(Cond, GEPLHS->getOperand(0),
2596 GEPRHS->getOperand(0));
2598 // Otherwise, the base pointers are different and the indices are
2599 // different, bail out.
2603 // If one of the GEPs has all zero indices, recurse.
2604 bool AllZeros = true;
2605 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2606 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
2607 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
2612 return FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0),
2613 SetCondInst::getSwappedCondition(Cond), I);
2615 // If the other GEP has all zero indices, recurse.
2617 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2618 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
2619 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
2624 return FoldGEPSetCC(GEPLHS, GEPRHS->getOperand(0), Cond, I);
2626 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
2627 // If the GEPs only differ by one index, compare it.
2628 unsigned NumDifferences = 0; // Keep track of # differences.
2629 unsigned DiffOperand = 0; // The operand that differs.
2630 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2631 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2632 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
2633 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
2634 // Irreconcilable differences.
2638 if (NumDifferences++) break;
2643 if (NumDifferences == 0) // SAME GEP?
2644 return ReplaceInstUsesWith(I, // No comparison is needed here.
2645 ConstantBool::get(Cond == Instruction::SetEQ));
2646 else if (NumDifferences == 1) {
2647 Value *LHSV = GEPLHS->getOperand(DiffOperand);
2648 Value *RHSV = GEPRHS->getOperand(DiffOperand);
2650 // Convert the operands to signed values to make sure to perform a
2651 // signed comparison.
2652 const Type *NewTy = LHSV->getType()->getSignedVersion();
2653 if (LHSV->getType() != NewTy)
2654 LHSV = InsertNewInstBefore(new CastInst(LHSV, NewTy,
2655 LHSV->getName()), I);
2656 if (RHSV->getType() != NewTy)
2657 RHSV = InsertNewInstBefore(new CastInst(RHSV, NewTy,
2658 RHSV->getName()), I);
2659 return new SetCondInst(Cond, LHSV, RHSV);
2663 // Only lower this if the setcc is the only user of the GEP or if we expect
2664 // the result to fold to a constant!
2665 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
2666 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
2667 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
2668 Value *L = EmitGEPOffset(GEPLHS, I, *this);
2669 Value *R = EmitGEPOffset(GEPRHS, I, *this);
2670 return new SetCondInst(Cond, L, R);
2677 Instruction *InstCombiner::visitSetCondInst(SetCondInst &I) {
2678 bool Changed = SimplifyCommutative(I);
2679 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2680 const Type *Ty = Op0->getType();
2684 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
2686 if (isa<UndefValue>(Op1)) // X setcc undef -> undef
2687 return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
2689 // setcc <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
2690 // addresses never equal each other! We already know that Op0 != Op1.
2691 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
2692 isa<ConstantPointerNull>(Op0)) &&
2693 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
2694 isa<ConstantPointerNull>(Op1)))
2695 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
2697 // setcc's with boolean values can always be turned into bitwise operations
2698 if (Ty == Type::BoolTy) {
2699 switch (I.getOpcode()) {
2700 default: assert(0 && "Invalid setcc instruction!");
2701 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
2702 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
2703 InsertNewInstBefore(Xor, I);
2704 return BinaryOperator::createNot(Xor);
2706 case Instruction::SetNE:
2707 return BinaryOperator::createXor(Op0, Op1);
2709 case Instruction::SetGT:
2710 std::swap(Op0, Op1); // Change setgt -> setlt
2712 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
2713 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2714 InsertNewInstBefore(Not, I);
2715 return BinaryOperator::createAnd(Not, Op1);
2717 case Instruction::SetGE:
2718 std::swap(Op0, Op1); // Change setge -> setle
2720 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
2721 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2722 InsertNewInstBefore(Not, I);
2723 return BinaryOperator::createOr(Not, Op1);
2728 // See if we are doing a comparison between a constant and an instruction that
2729 // can be folded into the comparison.
2730 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2731 // Check to see if we are comparing against the minimum or maximum value...
2732 if (CI->isMinValue()) {
2733 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
2734 return ReplaceInstUsesWith(I, ConstantBool::False);
2735 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
2736 return ReplaceInstUsesWith(I, ConstantBool::True);
2737 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
2738 return BinaryOperator::createSetEQ(Op0, Op1);
2739 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
2740 return BinaryOperator::createSetNE(Op0, Op1);
2742 } else if (CI->isMaxValue()) {
2743 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
2744 return ReplaceInstUsesWith(I, ConstantBool::False);
2745 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
2746 return ReplaceInstUsesWith(I, ConstantBool::True);
2747 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
2748 return BinaryOperator::createSetEQ(Op0, Op1);
2749 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
2750 return BinaryOperator::createSetNE(Op0, Op1);
2752 // Comparing against a value really close to min or max?
2753 } else if (isMinValuePlusOne(CI)) {
2754 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
2755 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
2756 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
2757 return BinaryOperator::createSetNE(Op0, SubOne(CI));
2759 } else if (isMaxValueMinusOne(CI)) {
2760 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
2761 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
2762 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
2763 return BinaryOperator::createSetNE(Op0, AddOne(CI));
2766 // If we still have a setle or setge instruction, turn it into the
2767 // appropriate setlt or setgt instruction. Since the border cases have
2768 // already been handled above, this requires little checking.
2770 if (I.getOpcode() == Instruction::SetLE)
2771 return BinaryOperator::createSetLT(Op0, AddOne(CI));
2772 if (I.getOpcode() == Instruction::SetGE)
2773 return BinaryOperator::createSetGT(Op0, SubOne(CI));
2775 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
2776 switch (LHSI->getOpcode()) {
2777 case Instruction::And:
2778 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
2779 LHSI->getOperand(0)->hasOneUse()) {
2780 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
2781 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
2782 // happens a LOT in code produced by the C front-end, for bitfield
2784 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
2785 ConstantUInt *ShAmt;
2786 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
2787 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
2788 const Type *Ty = LHSI->getType();
2790 // We can fold this as long as we can't shift unknown bits
2791 // into the mask. This can only happen with signed shift
2792 // rights, as they sign-extend.
2794 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
2795 Shift->getType()->isUnsigned();
2797 // To test for the bad case of the signed shr, see if any
2798 // of the bits shifted in could be tested after the mask.
2799 int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue();
2800 if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
2802 Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal);
2804 ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
2805 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
2811 if (Shift->getOpcode() == Instruction::Shl)
2812 NewCst = ConstantExpr::getUShr(CI, ShAmt);
2814 NewCst = ConstantExpr::getShl(CI, ShAmt);
2816 // Check to see if we are shifting out any of the bits being
2818 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
2819 // If we shifted bits out, the fold is not going to work out.
2820 // As a special case, check to see if this means that the
2821 // result is always true or false now.
2822 if (I.getOpcode() == Instruction::SetEQ)
2823 return ReplaceInstUsesWith(I, ConstantBool::False);
2824 if (I.getOpcode() == Instruction::SetNE)
2825 return ReplaceInstUsesWith(I, ConstantBool::True);
2827 I.setOperand(1, NewCst);
2828 Constant *NewAndCST;
2829 if (Shift->getOpcode() == Instruction::Shl)
2830 NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
2832 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
2833 LHSI->setOperand(1, NewAndCST);
2834 LHSI->setOperand(0, Shift->getOperand(0));
2835 WorkList.push_back(Shift); // Shift is dead.
2836 AddUsesToWorkList(I);
2844 case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
2845 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2846 switch (I.getOpcode()) {
2848 case Instruction::SetEQ:
2849 case Instruction::SetNE: {
2850 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2852 // Check that the shift amount is in range. If not, don't perform
2853 // undefined shifts. When the shift is visited it will be
2855 if (ShAmt->getValue() >= TypeBits)
2858 // If we are comparing against bits always shifted out, the
2859 // comparison cannot succeed.
2861 ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
2862 if (Comp != CI) {// Comparing against a bit that we know is zero.
2863 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2864 Constant *Cst = ConstantBool::get(IsSetNE);
2865 return ReplaceInstUsesWith(I, Cst);
2868 if (LHSI->hasOneUse()) {
2869 // Otherwise strength reduce the shift into an and.
2870 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2871 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
2874 if (CI->getType()->isUnsigned()) {
2875 Mask = ConstantUInt::get(CI->getType(), Val);
2876 } else if (ShAmtVal != 0) {
2877 Mask = ConstantSInt::get(CI->getType(), Val);
2879 Mask = ConstantInt::getAllOnesValue(CI->getType());
2883 BinaryOperator::createAnd(LHSI->getOperand(0),
2884 Mask, LHSI->getName()+".mask");
2885 Value *And = InsertNewInstBefore(AndI, I);
2886 return new SetCondInst(I.getOpcode(), And,
2887 ConstantExpr::getUShr(CI, ShAmt));
2894 case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
2895 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2896 switch (I.getOpcode()) {
2898 case Instruction::SetEQ:
2899 case Instruction::SetNE: {
2901 // Check that the shift amount is in range. If not, don't perform
2902 // undefined shifts. When the shift is visited it will be
2904 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2905 if (ShAmt->getValue() >= TypeBits)
2908 // If we are comparing against bits always shifted out, the
2909 // comparison cannot succeed.
2911 ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
2913 if (Comp != CI) {// Comparing against a bit that we know is zero.
2914 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2915 Constant *Cst = ConstantBool::get(IsSetNE);
2916 return ReplaceInstUsesWith(I, Cst);
2919 if (LHSI->hasOneUse() || CI->isNullValue()) {
2920 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2922 // Otherwise strength reduce the shift into an and.
2923 uint64_t Val = ~0ULL; // All ones.
2924 Val <<= ShAmtVal; // Shift over to the right spot.
2927 if (CI->getType()->isUnsigned()) {
2928 Val &= ~0ULL >> (64-TypeBits);
2929 Mask = ConstantUInt::get(CI->getType(), Val);
2931 Mask = ConstantSInt::get(CI->getType(), Val);
2935 BinaryOperator::createAnd(LHSI->getOperand(0),
2936 Mask, LHSI->getName()+".mask");
2937 Value *And = InsertNewInstBefore(AndI, I);
2938 return new SetCondInst(I.getOpcode(), And,
2939 ConstantExpr::getShl(CI, ShAmt));
2947 case Instruction::Div:
2948 // Fold: (div X, C1) op C2 -> range check
2949 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
2950 // Fold this div into the comparison, producing a range check.
2951 // Determine, based on the divide type, what the range is being
2952 // checked. If there is an overflow on the low or high side, remember
2953 // it, otherwise compute the range [low, hi) bounding the new value.
2954 bool LoOverflow = false, HiOverflow = 0;
2955 ConstantInt *LoBound = 0, *HiBound = 0;
2958 bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
2960 Instruction::BinaryOps Opcode = I.getOpcode();
2962 if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
2963 } else if (LHSI->getType()->isUnsigned()) { // udiv
2965 LoOverflow = ProdOV;
2966 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
2967 } else if (isPositive(DivRHS)) { // Divisor is > 0.
2968 if (CI->isNullValue()) { // (X / pos) op 0
2970 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
2972 } else if (isPositive(CI)) { // (X / pos) op pos
2974 LoOverflow = ProdOV;
2975 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
2976 } else { // (X / pos) op neg
2977 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
2978 LoOverflow = AddWithOverflow(LoBound, Prod,
2979 cast<ConstantInt>(DivRHSH));
2981 HiOverflow = ProdOV;
2983 } else { // Divisor is < 0.
2984 if (CI->isNullValue()) { // (X / neg) op 0
2985 LoBound = AddOne(DivRHS);
2986 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
2987 if (HiBound == DivRHS)
2988 LoBound = 0; // - INTMIN = INTMIN
2989 } else if (isPositive(CI)) { // (X / neg) op pos
2990 HiOverflow = LoOverflow = ProdOV;
2992 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
2993 HiBound = AddOne(Prod);
2994 } else { // (X / neg) op neg
2996 LoOverflow = HiOverflow = ProdOV;
2997 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
3000 // Dividing by a negate swaps the condition.
3001 Opcode = SetCondInst::getSwappedCondition(Opcode);
3005 Value *X = LHSI->getOperand(0);
3007 default: assert(0 && "Unhandled setcc opcode!");
3008 case Instruction::SetEQ:
3009 if (LoOverflow && HiOverflow)
3010 return ReplaceInstUsesWith(I, ConstantBool::False);
3011 else if (HiOverflow)
3012 return new SetCondInst(Instruction::SetGE, X, LoBound);
3013 else if (LoOverflow)
3014 return new SetCondInst(Instruction::SetLT, X, HiBound);
3016 return InsertRangeTest(X, LoBound, HiBound, true, I);
3017 case Instruction::SetNE:
3018 if (LoOverflow && HiOverflow)
3019 return ReplaceInstUsesWith(I, ConstantBool::True);
3020 else if (HiOverflow)
3021 return new SetCondInst(Instruction::SetLT, X, LoBound);
3022 else if (LoOverflow)
3023 return new SetCondInst(Instruction::SetGE, X, HiBound);
3025 return InsertRangeTest(X, LoBound, HiBound, false, I);
3026 case Instruction::SetLT:
3028 return ReplaceInstUsesWith(I, ConstantBool::False);
3029 return new SetCondInst(Instruction::SetLT, X, LoBound);
3030 case Instruction::SetGT:
3032 return ReplaceInstUsesWith(I, ConstantBool::False);
3033 return new SetCondInst(Instruction::SetGE, X, HiBound);
3040 // Simplify seteq and setne instructions...
3041 if (I.getOpcode() == Instruction::SetEQ ||
3042 I.getOpcode() == Instruction::SetNE) {
3043 bool isSetNE = I.getOpcode() == Instruction::SetNE;
3045 // If the first operand is (and|or|xor) with a constant, and the second
3046 // operand is a constant, simplify a bit.
3047 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
3048 switch (BO->getOpcode()) {
3049 case Instruction::Rem:
3050 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
3051 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
3053 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1) {
3054 int64_t V = cast<ConstantSInt>(BO->getOperand(1))->getValue();
3055 if (isPowerOf2_64(V)) {
3056 unsigned L2 = Log2_64(V);
3057 const Type *UTy = BO->getType()->getUnsignedVersion();
3058 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
3060 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
3061 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
3062 RHSCst, BO->getName()), I);
3063 return BinaryOperator::create(I.getOpcode(), NewRem,
3064 Constant::getNullValue(UTy));
3069 case Instruction::Add:
3070 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
3071 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3072 if (BO->hasOneUse())
3073 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
3074 ConstantExpr::getSub(CI, BOp1C));
3075 } else if (CI->isNullValue()) {
3076 // Replace ((add A, B) != 0) with (A != -B) if A or B is
3077 // efficiently invertible, or if the add has just this one use.
3078 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
3080 if (Value *NegVal = dyn_castNegVal(BOp1))
3081 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
3082 else if (Value *NegVal = dyn_castNegVal(BOp0))
3083 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
3084 else if (BO->hasOneUse()) {
3085 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
3087 InsertNewInstBefore(Neg, I);
3088 return new SetCondInst(I.getOpcode(), BOp0, Neg);
3092 case Instruction::Xor:
3093 // For the xor case, we can xor two constants together, eliminating
3094 // the explicit xor.
3095 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
3096 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
3097 ConstantExpr::getXor(CI, BOC));
3100 case Instruction::Sub:
3101 // Replace (([sub|xor] A, B) != 0) with (A != B)
3102 if (CI->isNullValue())
3103 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
3107 case Instruction::Or:
3108 // If bits are being or'd in that are not present in the constant we
3109 // are comparing against, then the comparison could never succeed!
3110 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
3111 Constant *NotCI = ConstantExpr::getNot(CI);
3112 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
3113 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3117 case Instruction::And:
3118 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3119 // If bits are being compared against that are and'd out, then the
3120 // comparison can never succeed!
3121 if (!ConstantExpr::getAnd(CI,
3122 ConstantExpr::getNot(BOC))->isNullValue())
3123 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3125 // If we have ((X & C) == C), turn it into ((X & C) != 0).
3126 if (CI == BOC && isOneBitSet(CI))
3127 return new SetCondInst(isSetNE ? Instruction::SetEQ :
3128 Instruction::SetNE, Op0,
3129 Constant::getNullValue(CI->getType()));
3131 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
3132 // to be a signed value as appropriate.
3133 if (isSignBit(BOC)) {
3134 Value *X = BO->getOperand(0);
3135 // If 'X' is not signed, insert a cast now...
3136 if (!BOC->getType()->isSigned()) {
3137 const Type *DestTy = BOC->getType()->getSignedVersion();
3138 X = InsertCastBefore(X, DestTy, I);
3140 return new SetCondInst(isSetNE ? Instruction::SetLT :
3141 Instruction::SetGE, X,
3142 Constant::getNullValue(X->getType()));
3145 // ((X & ~7) == 0) --> X < 8
3146 if (CI->isNullValue() && isHighOnes(BOC)) {
3147 Value *X = BO->getOperand(0);
3148 Constant *NegX = ConstantExpr::getNeg(BOC);
3150 // If 'X' is signed, insert a cast now.
3151 if (NegX->getType()->isSigned()) {
3152 const Type *DestTy = NegX->getType()->getUnsignedVersion();
3153 X = InsertCastBefore(X, DestTy, I);
3154 NegX = ConstantExpr::getCast(NegX, DestTy);
3157 return new SetCondInst(isSetNE ? Instruction::SetGE :
3158 Instruction::SetLT, X, NegX);
3165 } else { // Not a SetEQ/SetNE
3166 // If the LHS is a cast from an integral value of the same size,
3167 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
3168 Value *CastOp = Cast->getOperand(0);
3169 const Type *SrcTy = CastOp->getType();
3170 unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits();
3171 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
3172 SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
3173 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
3174 "Source and destination signednesses should differ!");
3175 if (Cast->getType()->isSigned()) {
3176 // If this is a signed comparison, check for comparisons in the
3177 // vicinity of zero.
3178 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
3180 return BinaryOperator::createSetGT(CastOp,
3181 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize-1))-1));
3182 else if (I.getOpcode() == Instruction::SetGT &&
3183 cast<ConstantSInt>(CI)->getValue() == -1)
3184 // X > -1 => x < 128
3185 return BinaryOperator::createSetLT(CastOp,
3186 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize-1)));
3188 ConstantUInt *CUI = cast<ConstantUInt>(CI);
3189 if (I.getOpcode() == Instruction::SetLT &&
3190 CUI->getValue() == 1ULL << (SrcTySize-1))
3191 // X < 128 => X > -1
3192 return BinaryOperator::createSetGT(CastOp,
3193 ConstantSInt::get(SrcTy, -1));
3194 else if (I.getOpcode() == Instruction::SetGT &&
3195 CUI->getValue() == (1ULL << (SrcTySize-1))-1)
3197 return BinaryOperator::createSetLT(CastOp,
3198 Constant::getNullValue(SrcTy));
3205 // Handle setcc with constant RHS's that can be integer, FP or pointer.
3206 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
3207 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3208 switch (LHSI->getOpcode()) {
3209 case Instruction::GetElementPtr:
3210 if (RHSC->isNullValue()) {
3211 // Transform setcc GEP P, int 0, int 0, int 0, null -> setcc P, null
3212 bool isAllZeros = true;
3213 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
3214 if (!isa<Constant>(LHSI->getOperand(i)) ||
3215 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
3220 return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),
3221 Constant::getNullValue(LHSI->getOperand(0)->getType()));
3225 case Instruction::PHI:
3226 if (Instruction *NV = FoldOpIntoPhi(I))
3229 case Instruction::Select:
3230 // If either operand of the select is a constant, we can fold the
3231 // comparison into the select arms, which will cause one to be
3232 // constant folded and the select turned into a bitwise or.
3233 Value *Op1 = 0, *Op2 = 0;
3234 if (LHSI->hasOneUse()) {
3235 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
3236 // Fold the known value into the constant operand.
3237 Op1 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3238 // Insert a new SetCC of the other select operand.
3239 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3240 LHSI->getOperand(2), RHSC,
3242 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
3243 // Fold the known value into the constant operand.
3244 Op2 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3245 // Insert a new SetCC of the other select operand.
3246 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3247 LHSI->getOperand(1), RHSC,
3253 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
3258 // If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now.
3259 if (User *GEP = dyn_castGetElementPtr(Op0))
3260 if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I))
3262 if (User *GEP = dyn_castGetElementPtr(Op1))
3263 if (Instruction *NI = FoldGEPSetCC(GEP, Op0,
3264 SetCondInst::getSwappedCondition(I.getOpcode()), I))
3267 // Test to see if the operands of the setcc are casted versions of other
3268 // values. If the cast can be stripped off both arguments, we do so now.
3269 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3270 Value *CastOp0 = CI->getOperand(0);
3271 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
3272 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
3273 (I.getOpcode() == Instruction::SetEQ ||
3274 I.getOpcode() == Instruction::SetNE)) {
3275 // We keep moving the cast from the left operand over to the right
3276 // operand, where it can often be eliminated completely.
3279 // If operand #1 is a cast instruction, see if we can eliminate it as
3281 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
3282 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
3284 Op1 = CI2->getOperand(0);
3286 // If Op1 is a constant, we can fold the cast into the constant.
3287 if (Op1->getType() != Op0->getType())
3288 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
3289 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
3291 // Otherwise, cast the RHS right before the setcc
3292 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
3293 InsertNewInstBefore(cast<Instruction>(Op1), I);
3295 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
3298 // Handle the special case of: setcc (cast bool to X), <cst>
3299 // This comes up when you have code like
3302 // For generality, we handle any zero-extension of any operand comparison
3303 // with a constant or another cast from the same type.
3304 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
3305 if (Instruction *R = visitSetCondInstWithCastAndCast(I))
3308 return Changed ? &I : 0;
3311 // visitSetCondInstWithCastAndCast - Handle setcond (cast x to y), (cast/cst).
3312 // We only handle extending casts so far.
3314 Instruction *InstCombiner::visitSetCondInstWithCastAndCast(SetCondInst &SCI) {
3315 Value *LHSCIOp = cast<CastInst>(SCI.getOperand(0))->getOperand(0);
3316 const Type *SrcTy = LHSCIOp->getType();
3317 const Type *DestTy = SCI.getOperand(0)->getType();
3320 if (!DestTy->isIntegral() || !SrcTy->isIntegral())
3323 unsigned SrcBits = SrcTy->getPrimitiveSizeInBits();
3324 unsigned DestBits = DestTy->getPrimitiveSizeInBits();
3325 if (SrcBits >= DestBits) return 0; // Only handle extending cast.
3327 // Is this a sign or zero extension?
3328 bool isSignSrc = SrcTy->isSigned();
3329 bool isSignDest = DestTy->isSigned();
3331 if (CastInst *CI = dyn_cast<CastInst>(SCI.getOperand(1))) {
3332 // Not an extension from the same type?
3333 RHSCIOp = CI->getOperand(0);
3334 if (RHSCIOp->getType() != LHSCIOp->getType()) return 0;
3335 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(SCI.getOperand(1))) {
3336 // Compute the constant that would happen if we truncated to SrcTy then
3337 // reextended to DestTy.
3338 Constant *Res = ConstantExpr::getCast(CI, SrcTy);
3340 if (ConstantExpr::getCast(Res, DestTy) == CI) {
3343 // If the value cannot be represented in the shorter type, we cannot emit
3344 // a simple comparison.
3345 if (SCI.getOpcode() == Instruction::SetEQ)
3346 return ReplaceInstUsesWith(SCI, ConstantBool::False);
3347 if (SCI.getOpcode() == Instruction::SetNE)
3348 return ReplaceInstUsesWith(SCI, ConstantBool::True);
3350 // Evaluate the comparison for LT.
3352 if (DestTy->isSigned()) {
3353 // We're performing a signed comparison.
3355 // Signed extend and signed comparison.
3356 if (cast<ConstantSInt>(CI)->getValue() < 0) // X < (small) --> false
3357 Result = ConstantBool::False;
3359 Result = ConstantBool::True; // X < (large) --> true
3361 // Unsigned extend and signed comparison.
3362 if (cast<ConstantSInt>(CI)->getValue() < 0)
3363 Result = ConstantBool::False;
3365 Result = ConstantBool::True;
3368 // We're performing an unsigned comparison.
3370 // Unsigned extend & compare -> always true.
3371 Result = ConstantBool::True;
3373 // We're performing an unsigned comp with a sign extended value.
3374 // This is true if the input is >= 0. [aka >s -1]
3375 Constant *NegOne = ConstantIntegral::getAllOnesValue(SrcTy);
3376 Result = InsertNewInstBefore(BinaryOperator::createSetGT(LHSCIOp,
3377 NegOne, SCI.getName()), SCI);
3381 // Finally, return the value computed.
3382 if (SCI.getOpcode() == Instruction::SetLT) {
3383 return ReplaceInstUsesWith(SCI, Result);
3385 assert(SCI.getOpcode()==Instruction::SetGT &&"SetCC should be folded!");
3386 if (Constant *CI = dyn_cast<Constant>(Result))
3387 return ReplaceInstUsesWith(SCI, ConstantExpr::getNot(CI));
3389 return BinaryOperator::createNot(Result);
3396 // Okay, just insert a compare of the reduced operands now!
3397 return BinaryOperator::create(SCI.getOpcode(), LHSCIOp, RHSCIOp);
3400 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
3401 assert(I.getOperand(1)->getType() == Type::UByteTy);
3402 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3403 bool isLeftShift = I.getOpcode() == Instruction::Shl;
3405 // shl X, 0 == X and shr X, 0 == X
3406 // shl 0, X == 0 and shr 0, X == 0
3407 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
3408 Op0 == Constant::getNullValue(Op0->getType()))
3409 return ReplaceInstUsesWith(I, Op0);
3411 if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
3412 if (!isLeftShift && I.getType()->isSigned())
3413 return ReplaceInstUsesWith(I, Op0);
3414 else // undef << X -> 0 AND undef >>u X -> 0
3415 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3417 if (isa<UndefValue>(Op1)) {
3418 if (isLeftShift || I.getType()->isUnsigned())// X << undef, X >>u undef -> 0
3419 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3421 return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X
3424 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
3426 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
3427 if (CSI->isAllOnesValue())
3428 return ReplaceInstUsesWith(I, CSI);
3430 // Try to fold constant and into select arguments.
3431 if (isa<Constant>(Op0))
3432 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
3433 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3436 // See if we can turn a signed shr into an unsigned shr.
3437 if (!isLeftShift && I.getType()->isSigned()) {
3438 if (MaskedValueIsZero(Op0, ConstantInt::getMinValue(I.getType()))) {
3439 Value *V = InsertCastBefore(Op0, I.getType()->getUnsignedVersion(), I);
3440 V = InsertNewInstBefore(new ShiftInst(Instruction::Shr, V, Op1,
3442 return new CastInst(V, I.getType());
3446 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1))
3447 if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
3452 Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantUInt *Op1,
3454 bool isLeftShift = I.getOpcode() == Instruction::Shl;
3455 bool isSignedShift = Op0->getType()->isSigned();
3456 bool isUnsignedShift = !isSignedShift;
3458 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
3459 // of a signed value.
3461 unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits();
3462 if (Op1->getValue() >= TypeBits) {
3463 if (isUnsignedShift || isLeftShift)
3464 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
3466 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
3471 // ((X*C1) << C2) == (X * (C1 << C2))
3472 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
3473 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
3474 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
3475 return BinaryOperator::createMul(BO->getOperand(0),
3476 ConstantExpr::getShl(BOOp, Op1));
3478 // Try to fold constant and into select arguments.
3479 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3480 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3482 if (isa<PHINode>(Op0))
3483 if (Instruction *NV = FoldOpIntoPhi(I))
3486 if (Op0->hasOneUse()) {
3487 // If this is a SHL of a sign-extending cast, see if we can turn the input
3488 // into a zero extending cast (a simple strength reduction).
3489 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3490 const Type *SrcTy = CI->getOperand(0)->getType();
3491 if (isLeftShift && SrcTy->isInteger() && SrcTy->isSigned() &&
3492 SrcTy->getPrimitiveSizeInBits() <
3493 CI->getType()->getPrimitiveSizeInBits()) {
3494 // We can change it to a zero extension if we are shifting out all of
3495 // the sign extended bits. To check this, form a mask of all of the
3496 // sign extend bits, then shift them left and see if we have anything
3498 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); // 1111
3499 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); // 00001111
3500 Mask = ConstantExpr::getNot(Mask); // 1's in the sign bits: 11110000
3501 if (ConstantExpr::getShl(Mask, Op1)->isNullValue()) {
3502 // If the shift is nuking all of the sign bits, change this to a
3503 // zero extension cast. To do this, cast the cast input to
3504 // unsigned, then to the requested size.
3505 Value *CastOp = CI->getOperand(0);
3507 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
3508 CI->getName()+".uns");
3509 NC = InsertNewInstBefore(NC, I);
3510 // Finally, insert a replacement for CI.
3511 NC = new CastInst(NC, CI->getType(), CI->getName());
3513 NC = InsertNewInstBefore(NC, I);
3514 WorkList.push_back(CI); // Delete CI later.
3515 I.setOperand(0, NC);
3516 return &I; // The SHL operand was modified.
3521 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
3522 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
3525 switch (Op0BO->getOpcode()) {
3527 case Instruction::Add:
3528 case Instruction::And:
3529 case Instruction::Or:
3530 case Instruction::Xor:
3531 // These operators commute.
3532 // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
3533 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
3534 match(Op0BO->getOperand(1),
3535 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
3536 Instruction *YS = new ShiftInst(Instruction::Shl,
3537 Op0BO->getOperand(0), Op1,
3539 InsertNewInstBefore(YS, I); // (Y << C)
3540 Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
3542 Op0BO->getOperand(1)->getName());
3543 InsertNewInstBefore(X, I); // (X + (Y << C))
3544 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
3545 C2 = ConstantExpr::getShl(C2, Op1);
3546 return BinaryOperator::createAnd(X, C2);
3549 // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
3550 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
3551 match(Op0BO->getOperand(1),
3552 m_And(m_Shr(m_Value(V1), m_Value(V2)),
3553 m_ConstantInt(CC))) && V2 == Op1 &&
3554 cast<BinaryOperator>(Op0BO->getOperand(1))->getOperand(0)->hasOneUse()) {
3555 Instruction *YS = new ShiftInst(Instruction::Shl,
3556 Op0BO->getOperand(0), Op1,
3558 InsertNewInstBefore(YS, I); // (Y << C)
3560 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
3561 V1->getName()+".mask");
3562 InsertNewInstBefore(XM, I); // X & (CC << C)
3564 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
3568 case Instruction::Sub:
3569 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
3570 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
3571 match(Op0BO->getOperand(0),
3572 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
3573 Instruction *YS = new ShiftInst(Instruction::Shl,
3574 Op0BO->getOperand(1), Op1,
3576 InsertNewInstBefore(YS, I); // (Y << C)
3577 Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
3579 Op0BO->getOperand(0)->getName());
3580 InsertNewInstBefore(X, I); // (X + (Y << C))
3581 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
3582 C2 = ConstantExpr::getShl(C2, Op1);
3583 return BinaryOperator::createAnd(X, C2);
3586 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
3587 match(Op0BO->getOperand(0),
3588 m_And(m_Shr(m_Value(V1), m_Value(V2)),
3589 m_ConstantInt(CC))) && V2 == Op1 &&
3590 cast<BinaryOperator>(Op0BO->getOperand(0))->getOperand(0)->hasOneUse()) {
3591 Instruction *YS = new ShiftInst(Instruction::Shl,
3592 Op0BO->getOperand(1), Op1,
3594 InsertNewInstBefore(YS, I); // (Y << C)
3596 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
3597 V1->getName()+".mask");
3598 InsertNewInstBefore(XM, I); // X & (CC << C)
3600 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
3607 // If the operand is an bitwise operator with a constant RHS, and the
3608 // shift is the only use, we can pull it out of the shift.
3609 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
3610 bool isValid = true; // Valid only for And, Or, Xor
3611 bool highBitSet = false; // Transform if high bit of constant set?
3613 switch (Op0BO->getOpcode()) {
3614 default: isValid = false; break; // Do not perform transform!
3615 case Instruction::Add:
3616 isValid = isLeftShift;
3618 case Instruction::Or:
3619 case Instruction::Xor:
3622 case Instruction::And:
3627 // If this is a signed shift right, and the high bit is modified
3628 // by the logical operation, do not perform the transformation.
3629 // The highBitSet boolean indicates the value of the high bit of
3630 // the constant which would cause it to be modified for this
3633 if (isValid && !isLeftShift && isSignedShift) {
3634 uint64_t Val = Op0C->getRawValue();
3635 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
3639 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
3641 Instruction *NewShift =
3642 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), Op1,
3645 InsertNewInstBefore(NewShift, I);
3647 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
3654 // Find out if this is a shift of a shift by a constant.
3655 ShiftInst *ShiftOp = 0;
3656 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
3658 else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3659 // If this is a noop-integer case of a shift instruction, use the shift.
3660 if (CI->getOperand(0)->getType()->isInteger() &&
3661 CI->getOperand(0)->getType()->getPrimitiveSizeInBits() ==
3662 CI->getType()->getPrimitiveSizeInBits() &&
3663 isa<ShiftInst>(CI->getOperand(0))) {
3664 ShiftOp = cast<ShiftInst>(CI->getOperand(0));
3668 if (ShiftOp && isa<ConstantUInt>(ShiftOp->getOperand(1))) {
3669 // Find the operands and properties of the input shift. Note that the
3670 // signedness of the input shift may differ from the current shift if there
3671 // is a noop cast between the two.
3672 bool isShiftOfLeftShift = ShiftOp->getOpcode() == Instruction::Shl;
3673 bool isShiftOfSignedShift = ShiftOp->getType()->isSigned();
3674 bool isShiftOfUnsignedShift = !isShiftOfSignedShift;
3676 ConstantUInt *ShiftAmt1C = cast<ConstantUInt>(ShiftOp->getOperand(1));
3678 unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getValue();
3679 unsigned ShiftAmt2 = (unsigned)Op1->getValue();
3681 // Check for (A << c1) << c2 and (A >> c1) >> c2.
3682 if (isLeftShift == isShiftOfLeftShift) {
3683 // Do not fold these shifts if the first one is signed and the second one
3684 // is unsigned and this is a right shift. Further, don't do any folding
3686 if (isShiftOfSignedShift && isUnsignedShift && !isLeftShift)
3689 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift.
3690 if (Amt > Op0->getType()->getPrimitiveSizeInBits())
3691 Amt = Op0->getType()->getPrimitiveSizeInBits();
3693 Value *Op = ShiftOp->getOperand(0);
3694 if (isShiftOfSignedShift != isSignedShift)
3695 Op = InsertNewInstBefore(new CastInst(Op, I.getType(), "tmp"), I);
3696 return new ShiftInst(I.getOpcode(), Op,
3697 ConstantUInt::get(Type::UByteTy, Amt));
3700 // Check for (A << c1) >> c2 or (A >> c1) << c2. If we are dealing with
3701 // signed types, we can only support the (A >> c1) << c2 configuration,
3702 // because it can not turn an arbitrary bit of A into a sign bit.
3703 if (isUnsignedShift || isLeftShift) {
3704 // Calculate bitmask for what gets shifted off the edge.
3705 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
3707 C = ConstantExpr::getShl(C, ShiftAmt1C);
3709 C = ConstantExpr::getUShr(C, ShiftAmt1C);
3711 Value *Op = ShiftOp->getOperand(0);
3712 if (isShiftOfSignedShift != isSignedShift)
3713 Op = InsertNewInstBefore(new CastInst(Op, I.getType(),Op->getName()),I);
3716 BinaryOperator::createAnd(Op, C, Op->getName()+".mask");
3717 InsertNewInstBefore(Mask, I);
3719 // Figure out what flavor of shift we should use...
3720 if (ShiftAmt1 == ShiftAmt2) {
3721 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
3722 } else if (ShiftAmt1 < ShiftAmt2) {
3723 return new ShiftInst(I.getOpcode(), Mask,
3724 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
3725 } else if (isShiftOfUnsignedShift || isShiftOfLeftShift) {
3726 if (isShiftOfUnsignedShift && !isShiftOfLeftShift && isSignedShift) {
3727 // Make sure to emit an unsigned shift right, not a signed one.
3728 Mask = InsertNewInstBefore(new CastInst(Mask,
3729 Mask->getType()->getUnsignedVersion(),
3731 Mask = new ShiftInst(Instruction::Shr, Mask,
3732 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
3733 InsertNewInstBefore(Mask, I);
3734 return new CastInst(Mask, I.getType());
3736 return new ShiftInst(ShiftOp->getOpcode(), Mask,
3737 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
3740 // (X >>s C1) << C2 where C1 > C2 === (X >>s (C1-C2)) & mask
3741 Op = InsertNewInstBefore(new CastInst(Mask,
3742 I.getType()->getSignedVersion(),
3743 Mask->getName()), I);
3744 Instruction *Shift =
3745 new ShiftInst(ShiftOp->getOpcode(), Op,
3746 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
3747 InsertNewInstBefore(Shift, I);
3749 C = ConstantIntegral::getAllOnesValue(Shift->getType());
3750 C = ConstantExpr::getShl(C, Op1);
3751 Mask = BinaryOperator::createAnd(Shift, C, Op->getName()+".mask");
3752 InsertNewInstBefore(Mask, I);
3753 return new CastInst(Mask, I.getType());
3756 // We can handle signed (X << C1) >>s C2 if it's a sign extend. In
3757 // this case, C1 == C2 and C1 is 8, 16, or 32.
3758 if (ShiftAmt1 == ShiftAmt2) {
3759 const Type *SExtType = 0;
3760 switch (ShiftAmt1) {
3761 case 8 : SExtType = Type::SByteTy; break;
3762 case 16: SExtType = Type::ShortTy; break;
3763 case 32: SExtType = Type::IntTy; break;
3767 Instruction *NewTrunc = new CastInst(ShiftOp->getOperand(0),
3769 InsertNewInstBefore(NewTrunc, I);
3770 return new CastInst(NewTrunc, I.getType());
3785 /// getCastType - In the future, we will split the cast instruction into these
3786 /// various types. Until then, we have to do the analysis here.
3787 static CastType getCastType(const Type *Src, const Type *Dest) {
3788 assert(Src->isIntegral() && Dest->isIntegral() &&
3789 "Only works on integral types!");
3790 unsigned SrcSize = Src->getPrimitiveSizeInBits();
3791 unsigned DestSize = Dest->getPrimitiveSizeInBits();
3793 if (SrcSize == DestSize) return Noop;
3794 if (SrcSize > DestSize) return Truncate;
3795 if (Src->isSigned()) return Signext;
3800 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
3803 static bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
3804 const Type *DstTy, TargetData *TD) {
3806 // It is legal to eliminate the instruction if casting A->B->A if the sizes
3807 // are identical and the bits don't get reinterpreted (for example
3808 // int->float->int would not be allowed).
3809 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
3812 // If we are casting between pointer and integer types, treat pointers as
3813 // integers of the appropriate size for the code below.
3814 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
3815 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
3816 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
3818 // Allow free casting and conversion of sizes as long as the sign doesn't
3820 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
3821 CastType FirstCast = getCastType(SrcTy, MidTy);
3822 CastType SecondCast = getCastType(MidTy, DstTy);
3824 // Capture the effect of these two casts. If the result is a legal cast,
3825 // the CastType is stored here, otherwise a special code is used.
3826 static const unsigned CastResult[] = {
3827 // First cast is noop
3829 // First cast is a truncate
3830 1, 1, 4, 4, // trunc->extend is not safe to eliminate
3831 // First cast is a sign ext
3832 2, 5, 2, 4, // signext->zeroext never ok
3833 // First cast is a zero ext
3837 unsigned Result = CastResult[FirstCast*4+SecondCast];
3839 default: assert(0 && "Illegal table value!");
3844 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
3845 // truncates, we could eliminate more casts.
3846 return (unsigned)getCastType(SrcTy, DstTy) == Result;
3848 return false; // Not possible to eliminate this here.
3850 // Sign or zero extend followed by truncate is always ok if the result
3851 // is a truncate or noop.
3852 CastType ResultCast = getCastType(SrcTy, DstTy);
3853 if (ResultCast == Noop || ResultCast == Truncate)
3855 // Otherwise we are still growing the value, we are only safe if the
3856 // result will match the sign/zeroextendness of the result.
3857 return ResultCast == FirstCast;
3861 // If this is a cast from 'float -> double -> integer', cast from
3862 // 'float -> integer' directly, as the value isn't changed by the
3863 // float->double conversion.
3864 if (SrcTy->isFloatingPoint() && MidTy->isFloatingPoint() &&
3865 DstTy->isIntegral() &&
3866 SrcTy->getPrimitiveSize() < MidTy->getPrimitiveSize())
3872 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
3873 if (V->getType() == Ty || isa<Constant>(V)) return false;
3874 if (const CastInst *CI = dyn_cast<CastInst>(V))
3875 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
3881 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
3882 /// InsertBefore instruction. This is specialized a bit to avoid inserting
3883 /// casts that are known to not do anything...
3885 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
3886 Instruction *InsertBefore) {
3887 if (V->getType() == DestTy) return V;
3888 if (Constant *C = dyn_cast<Constant>(V))
3889 return ConstantExpr::getCast(C, DestTy);
3891 CastInst *CI = new CastInst(V, DestTy, V->getName());
3892 InsertNewInstBefore(CI, *InsertBefore);
3896 /// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
3897 /// expression. If so, decompose it, returning some value X, such that Val is
3900 static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
3902 assert(Val->getType() == Type::UIntTy && "Unexpected allocation size type!");
3903 if (ConstantUInt *CI = dyn_cast<ConstantUInt>(Val)) {
3904 Offset = CI->getValue();
3906 return ConstantUInt::get(Type::UIntTy, 0);
3907 } else if (Instruction *I = dyn_cast<Instruction>(Val)) {
3908 if (I->getNumOperands() == 2) {
3909 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(I->getOperand(1))) {
3910 if (I->getOpcode() == Instruction::Shl) {
3911 // This is a value scaled by '1 << the shift amt'.
3912 Scale = 1U << CUI->getValue();
3914 return I->getOperand(0);
3915 } else if (I->getOpcode() == Instruction::Mul) {
3916 // This value is scaled by 'CUI'.
3917 Scale = CUI->getValue();
3919 return I->getOperand(0);
3920 } else if (I->getOpcode() == Instruction::Add) {
3921 // We have X+C. Check to see if we really have (X*C2)+C1, where C1 is
3924 Value *SubVal = DecomposeSimpleLinearExpr(I->getOperand(0), SubScale,
3926 Offset += CUI->getValue();
3927 if (SubScale > 1 && (Offset % SubScale == 0)) {
3936 // Otherwise, we can't look past this.
3943 /// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
3944 /// try to eliminate the cast by moving the type information into the alloc.
3945 Instruction *InstCombiner::PromoteCastOfAllocation(CastInst &CI,
3946 AllocationInst &AI) {
3947 const PointerType *PTy = dyn_cast<PointerType>(CI.getType());
3948 if (!PTy) return 0; // Not casting the allocation to a pointer type.
3950 // Remove any uses of AI that are dead.
3951 assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
3952 std::vector<Instruction*> DeadUsers;
3953 for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
3954 Instruction *User = cast<Instruction>(*UI++);
3955 if (isInstructionTriviallyDead(User)) {
3956 while (UI != E && *UI == User)
3957 ++UI; // If this instruction uses AI more than once, don't break UI.
3959 // Add operands to the worklist.
3960 AddUsesToWorkList(*User);
3962 DEBUG(std::cerr << "IC: DCE: " << *User);
3964 User->eraseFromParent();
3965 removeFromWorkList(User);
3969 // Get the type really allocated and the type casted to.
3970 const Type *AllocElTy = AI.getAllocatedType();
3971 const Type *CastElTy = PTy->getElementType();
3972 if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
3974 unsigned AllocElTyAlign = TD->getTypeSize(AllocElTy);
3975 unsigned CastElTyAlign = TD->getTypeSize(CastElTy);
3976 if (CastElTyAlign < AllocElTyAlign) return 0;
3978 // If the allocation has multiple uses, only promote it if we are strictly
3979 // increasing the alignment of the resultant allocation. If we keep it the
3980 // same, we open the door to infinite loops of various kinds.
3981 if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return 0;
3983 uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
3984 uint64_t CastElTySize = TD->getTypeSize(CastElTy);
3985 if (CastElTySize == 0 || AllocElTySize == 0) return 0;
3987 // See if we can satisfy the modulus by pulling a scale out of the array
3989 unsigned ArraySizeScale, ArrayOffset;
3990 Value *NumElements = // See if the array size is a decomposable linear expr.
3991 DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
3993 // If we can now satisfy the modulus, by using a non-1 scale, we really can
3995 if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
3996 (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
3998 unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
4003 Amt = ConstantUInt::get(Type::UIntTy, Scale);
4004 if (ConstantUInt *CI = dyn_cast<ConstantUInt>(NumElements))
4005 Amt = ConstantExpr::getMul(CI, cast<ConstantUInt>(Amt));
4006 else if (Scale != 1) {
4007 Instruction *Tmp = BinaryOperator::createMul(Amt, NumElements, "tmp");
4008 Amt = InsertNewInstBefore(Tmp, AI);
4012 if (unsigned Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
4013 Value *Off = ConstantUInt::get(Type::UIntTy, Offset);
4014 Instruction *Tmp = BinaryOperator::createAdd(Amt, Off, "tmp");
4015 Amt = InsertNewInstBefore(Tmp, AI);
4018 std::string Name = AI.getName(); AI.setName("");
4019 AllocationInst *New;
4020 if (isa<MallocInst>(AI))
4021 New = new MallocInst(CastElTy, Amt, AI.getAlignment(), Name);
4023 New = new AllocaInst(CastElTy, Amt, AI.getAlignment(), Name);
4024 InsertNewInstBefore(New, AI);
4026 // If the allocation has multiple uses, insert a cast and change all things
4027 // that used it to use the new cast. This will also hack on CI, but it will
4029 if (!AI.hasOneUse()) {
4030 AddUsesToWorkList(AI);
4031 CastInst *NewCast = new CastInst(New, AI.getType(), "tmpcast");
4032 InsertNewInstBefore(NewCast, AI);
4033 AI.replaceAllUsesWith(NewCast);
4035 return ReplaceInstUsesWith(CI, New);
4039 // CastInst simplification
4041 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
4042 Value *Src = CI.getOperand(0);
4044 // If the user is casting a value to the same type, eliminate this cast
4046 if (CI.getType() == Src->getType())
4047 return ReplaceInstUsesWith(CI, Src);
4049 if (isa<UndefValue>(Src)) // cast undef -> undef
4050 return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
4052 // If casting the result of another cast instruction, try to eliminate this
4055 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
4056 Value *A = CSrc->getOperand(0);
4057 if (isEliminableCastOfCast(A->getType(), CSrc->getType(),
4058 CI.getType(), TD)) {
4059 // This instruction now refers directly to the cast's src operand. This
4060 // has a good chance of making CSrc dead.
4061 CI.setOperand(0, CSrc->getOperand(0));
4065 // If this is an A->B->A cast, and we are dealing with integral types, try
4066 // to convert this into a logical 'and' instruction.
4068 if (A->getType()->isInteger() &&
4069 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
4070 CSrc->getType()->isUnsigned() && // B->A cast must zero extend
4071 CSrc->getType()->getPrimitiveSizeInBits() <
4072 CI.getType()->getPrimitiveSizeInBits()&&
4073 A->getType()->getPrimitiveSizeInBits() ==
4074 CI.getType()->getPrimitiveSizeInBits()) {
4075 assert(CSrc->getType() != Type::ULongTy &&
4076 "Cannot have type bigger than ulong!");
4077 uint64_t AndValue = ~0ULL>>(64-CSrc->getType()->getPrimitiveSizeInBits());
4078 Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(),
4080 AndOp = ConstantExpr::getCast(AndOp, A->getType());
4081 Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
4082 if (And->getType() != CI.getType()) {
4083 And->setName(CSrc->getName()+".mask");
4084 InsertNewInstBefore(And, CI);
4085 And = new CastInst(And, CI.getType());
4091 // If this is a cast to bool, turn it into the appropriate setne instruction.
4092 if (CI.getType() == Type::BoolTy)
4093 return BinaryOperator::createSetNE(CI.getOperand(0),
4094 Constant::getNullValue(CI.getOperand(0)->getType()));
4096 // If casting the result of a getelementptr instruction with no offset, turn
4097 // this into a cast of the original pointer!
4099 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
4100 bool AllZeroOperands = true;
4101 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
4102 if (!isa<Constant>(GEP->getOperand(i)) ||
4103 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
4104 AllZeroOperands = false;
4107 if (AllZeroOperands) {
4108 CI.setOperand(0, GEP->getOperand(0));
4113 // If we are casting a malloc or alloca to a pointer to a type of the same
4114 // size, rewrite the allocation instruction to allocate the "right" type.
4116 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
4117 if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
4120 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
4121 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
4123 if (isa<PHINode>(Src))
4124 if (Instruction *NV = FoldOpIntoPhi(CI))
4127 // If the source value is an instruction with only this use, we can attempt to
4128 // propagate the cast into the instruction. Also, only handle integral types
4130 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
4131 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
4132 CI.getType()->isInteger()) { // Don't mess with casts to bool here
4133 const Type *DestTy = CI.getType();
4134 unsigned SrcBitSize = Src->getType()->getPrimitiveSizeInBits();
4135 unsigned DestBitSize = DestTy->getPrimitiveSizeInBits();
4137 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
4138 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
4140 switch (SrcI->getOpcode()) {
4141 case Instruction::Add:
4142 case Instruction::Mul:
4143 case Instruction::And:
4144 case Instruction::Or:
4145 case Instruction::Xor:
4146 // If we are discarding information, or just changing the sign, rewrite.
4147 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
4148 // Don't insert two casts if they cannot be eliminated. We allow two
4149 // casts to be inserted if the sizes are the same. This could only be
4150 // converting signedness, which is a noop.
4151 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
4152 !ValueRequiresCast(Op0, DestTy, TD)) {
4153 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
4154 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
4155 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
4156 ->getOpcode(), Op0c, Op1c);
4160 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
4161 if (SrcBitSize == 1 && SrcI->getOpcode() == Instruction::Xor &&
4162 Op1 == ConstantBool::True &&
4163 (!Op0->hasOneUse() || !isa<SetCondInst>(Op0))) {
4164 Value *New = InsertOperandCastBefore(Op0, DestTy, &CI);
4165 return BinaryOperator::createXor(New,
4166 ConstantInt::get(CI.getType(), 1));
4169 case Instruction::Shl:
4170 // Allow changing the sign of the source operand. Do not allow changing
4171 // the size of the shift, UNLESS the shift amount is a constant. We
4172 // mush not change variable sized shifts to a smaller size, because it
4173 // is undefined to shift more bits out than exist in the value.
4174 if (DestBitSize == SrcBitSize ||
4175 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
4176 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
4177 return new ShiftInst(Instruction::Shl, Op0c, Op1);
4180 case Instruction::Shr:
4181 // If this is a signed shr, and if all bits shifted in are about to be
4182 // truncated off, turn it into an unsigned shr to allow greater
4184 if (DestBitSize < SrcBitSize && Src->getType()->isSigned() &&
4185 isa<ConstantInt>(Op1)) {
4186 unsigned ShiftAmt = cast<ConstantUInt>(Op1)->getValue();
4187 if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
4188 // Convert to unsigned.
4189 Value *N1 = InsertOperandCastBefore(Op0,
4190 Op0->getType()->getUnsignedVersion(), &CI);
4191 // Insert the new shift, which is now unsigned.
4192 N1 = InsertNewInstBefore(new ShiftInst(Instruction::Shr, N1,
4193 Op1, Src->getName()), CI);
4194 return new CastInst(N1, CI.getType());
4199 case Instruction::SetNE:
4200 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
4201 if (Op1C->getRawValue() == 0) {
4202 // If the input only has the low bit set, simplify directly.
4204 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
4205 // cast (X != 0) to int --> X if X&~1 == 0
4206 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
4207 if (CI.getType() == Op0->getType())
4208 return ReplaceInstUsesWith(CI, Op0);
4210 return new CastInst(Op0, CI.getType());
4213 // If the input is an and with a single bit, shift then simplify.
4214 ConstantInt *AndRHS;
4215 if (match(Op0, m_And(m_Value(), m_ConstantInt(AndRHS))))
4216 if (AndRHS->getRawValue() &&
4217 (AndRHS->getRawValue() & (AndRHS->getRawValue()-1)) == 0) {
4218 unsigned ShiftAmt = Log2_64(AndRHS->getRawValue());
4219 // Perform an unsigned shr by shiftamt. Convert input to
4220 // unsigned if it is signed.
4222 if (In->getType()->isSigned())
4223 In = InsertNewInstBefore(new CastInst(In,
4224 In->getType()->getUnsignedVersion(), In->getName()),CI);
4225 // Insert the shift to put the result in the low bit.
4226 In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In,
4227 ConstantInt::get(Type::UByteTy, ShiftAmt),
4228 In->getName()+".lobit"), CI);
4229 if (CI.getType() == In->getType())
4230 return ReplaceInstUsesWith(CI, In);
4232 return new CastInst(In, CI.getType());
4237 case Instruction::SetEQ:
4238 // We if we are just checking for a seteq of a single bit and casting it
4239 // to an integer. If so, shift the bit to the appropriate place then
4240 // cast to integer to avoid the comparison.
4241 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
4242 // Is Op1C a power of two or zero?
4243 if ((Op1C->getRawValue() & Op1C->getRawValue()-1) == 0) {
4244 // cast (X == 1) to int -> X iff X has only the low bit set.
4245 if (Op1C->getRawValue() == 1) {
4247 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
4248 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
4249 if (CI.getType() == Op0->getType())
4250 return ReplaceInstUsesWith(CI, Op0);
4252 return new CastInst(Op0, CI.getType());
4264 /// GetSelectFoldableOperands - We want to turn code that looks like this:
4266 /// %D = select %cond, %C, %A
4268 /// %C = select %cond, %B, 0
4271 /// Assuming that the specified instruction is an operand to the select, return
4272 /// a bitmask indicating which operands of this instruction are foldable if they
4273 /// equal the other incoming value of the select.
4275 static unsigned GetSelectFoldableOperands(Instruction *I) {
4276 switch (I->getOpcode()) {
4277 case Instruction::Add:
4278 case Instruction::Mul:
4279 case Instruction::And:
4280 case Instruction::Or:
4281 case Instruction::Xor:
4282 return 3; // Can fold through either operand.
4283 case Instruction::Sub: // Can only fold on the amount subtracted.
4284 case Instruction::Shl: // Can only fold on the shift amount.
4285 case Instruction::Shr:
4288 return 0; // Cannot fold
4292 /// GetSelectFoldableConstant - For the same transformation as the previous
4293 /// function, return the identity constant that goes into the select.
4294 static Constant *GetSelectFoldableConstant(Instruction *I) {
4295 switch (I->getOpcode()) {
4296 default: assert(0 && "This cannot happen!"); abort();
4297 case Instruction::Add:
4298 case Instruction::Sub:
4299 case Instruction::Or:
4300 case Instruction::Xor:
4301 return Constant::getNullValue(I->getType());
4302 case Instruction::Shl:
4303 case Instruction::Shr:
4304 return Constant::getNullValue(Type::UByteTy);
4305 case Instruction::And:
4306 return ConstantInt::getAllOnesValue(I->getType());
4307 case Instruction::Mul:
4308 return ConstantInt::get(I->getType(), 1);
4312 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
4313 /// have the same opcode and only one use each. Try to simplify this.
4314 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
4316 if (TI->getNumOperands() == 1) {
4317 // If this is a non-volatile load or a cast from the same type,
4319 if (TI->getOpcode() == Instruction::Cast) {
4320 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
4323 return 0; // unknown unary op.
4326 // Fold this by inserting a select from the input values.
4327 SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
4328 FI->getOperand(0), SI.getName()+".v");
4329 InsertNewInstBefore(NewSI, SI);
4330 return new CastInst(NewSI, TI->getType());
4333 // Only handle binary operators here.
4334 if (!isa<ShiftInst>(TI) && !isa<BinaryOperator>(TI))
4337 // Figure out if the operations have any operands in common.
4338 Value *MatchOp, *OtherOpT, *OtherOpF;
4340 if (TI->getOperand(0) == FI->getOperand(0)) {
4341 MatchOp = TI->getOperand(0);
4342 OtherOpT = TI->getOperand(1);
4343 OtherOpF = FI->getOperand(1);
4344 MatchIsOpZero = true;
4345 } else if (TI->getOperand(1) == FI->getOperand(1)) {
4346 MatchOp = TI->getOperand(1);
4347 OtherOpT = TI->getOperand(0);
4348 OtherOpF = FI->getOperand(0);
4349 MatchIsOpZero = false;
4350 } else if (!TI->isCommutative()) {
4352 } else if (TI->getOperand(0) == FI->getOperand(1)) {
4353 MatchOp = TI->getOperand(0);
4354 OtherOpT = TI->getOperand(1);
4355 OtherOpF = FI->getOperand(0);
4356 MatchIsOpZero = true;
4357 } else if (TI->getOperand(1) == FI->getOperand(0)) {
4358 MatchOp = TI->getOperand(1);
4359 OtherOpT = TI->getOperand(0);
4360 OtherOpF = FI->getOperand(1);
4361 MatchIsOpZero = true;
4366 // If we reach here, they do have operations in common.
4367 SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
4368 OtherOpF, SI.getName()+".v");
4369 InsertNewInstBefore(NewSI, SI);
4371 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
4373 return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
4375 return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
4378 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI);
4380 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp);
4384 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
4385 Value *CondVal = SI.getCondition();
4386 Value *TrueVal = SI.getTrueValue();
4387 Value *FalseVal = SI.getFalseValue();
4389 // select true, X, Y -> X
4390 // select false, X, Y -> Y
4391 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
4392 if (C == ConstantBool::True)
4393 return ReplaceInstUsesWith(SI, TrueVal);
4395 assert(C == ConstantBool::False);
4396 return ReplaceInstUsesWith(SI, FalseVal);
4399 // select C, X, X -> X
4400 if (TrueVal == FalseVal)
4401 return ReplaceInstUsesWith(SI, TrueVal);
4403 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
4404 return ReplaceInstUsesWith(SI, FalseVal);
4405 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
4406 return ReplaceInstUsesWith(SI, TrueVal);
4407 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
4408 if (isa<Constant>(TrueVal))
4409 return ReplaceInstUsesWith(SI, TrueVal);
4411 return ReplaceInstUsesWith(SI, FalseVal);
4414 if (SI.getType() == Type::BoolTy)
4415 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
4416 if (C == ConstantBool::True) {
4417 // Change: A = select B, true, C --> A = or B, C
4418 return BinaryOperator::createOr(CondVal, FalseVal);
4420 // Change: A = select B, false, C --> A = and !B, C
4422 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4423 "not."+CondVal->getName()), SI);
4424 return BinaryOperator::createAnd(NotCond, FalseVal);
4426 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
4427 if (C == ConstantBool::False) {
4428 // Change: A = select B, C, false --> A = and B, C
4429 return BinaryOperator::createAnd(CondVal, TrueVal);
4431 // Change: A = select B, C, true --> A = or !B, C
4433 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4434 "not."+CondVal->getName()), SI);
4435 return BinaryOperator::createOr(NotCond, TrueVal);
4439 // Selecting between two integer constants?
4440 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
4441 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
4442 // select C, 1, 0 -> cast C to int
4443 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
4444 return new CastInst(CondVal, SI.getType());
4445 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
4446 // select C, 0, 1 -> cast !C to int
4448 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4449 "not."+CondVal->getName()), SI);
4450 return new CastInst(NotCond, SI.getType());
4453 // If one of the constants is zero (we know they can't both be) and we
4454 // have a setcc instruction with zero, and we have an 'and' with the
4455 // non-constant value, eliminate this whole mess. This corresponds to
4456 // cases like this: ((X & 27) ? 27 : 0)
4457 if (TrueValC->isNullValue() || FalseValC->isNullValue())
4458 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
4459 if ((IC->getOpcode() == Instruction::SetEQ ||
4460 IC->getOpcode() == Instruction::SetNE) &&
4461 isa<ConstantInt>(IC->getOperand(1)) &&
4462 cast<Constant>(IC->getOperand(1))->isNullValue())
4463 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
4464 if (ICA->getOpcode() == Instruction::And &&
4465 isa<ConstantInt>(ICA->getOperand(1)) &&
4466 (ICA->getOperand(1) == TrueValC ||
4467 ICA->getOperand(1) == FalseValC) &&
4468 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
4469 // Okay, now we know that everything is set up, we just don't
4470 // know whether we have a setne or seteq and whether the true or
4471 // false val is the zero.
4472 bool ShouldNotVal = !TrueValC->isNullValue();
4473 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
4476 V = InsertNewInstBefore(BinaryOperator::create(
4477 Instruction::Xor, V, ICA->getOperand(1)), SI);
4478 return ReplaceInstUsesWith(SI, V);
4482 // See if we are selecting two values based on a comparison of the two values.
4483 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
4484 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
4485 // Transform (X == Y) ? X : Y -> Y
4486 if (SCI->getOpcode() == Instruction::SetEQ)
4487 return ReplaceInstUsesWith(SI, FalseVal);
4488 // Transform (X != Y) ? X : Y -> X
4489 if (SCI->getOpcode() == Instruction::SetNE)
4490 return ReplaceInstUsesWith(SI, TrueVal);
4491 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
4493 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
4494 // Transform (X == Y) ? Y : X -> X
4495 if (SCI->getOpcode() == Instruction::SetEQ)
4496 return ReplaceInstUsesWith(SI, FalseVal);
4497 // Transform (X != Y) ? Y : X -> Y
4498 if (SCI->getOpcode() == Instruction::SetNE)
4499 return ReplaceInstUsesWith(SI, TrueVal);
4500 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
4504 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
4505 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
4506 if (TI->hasOneUse() && FI->hasOneUse()) {
4507 bool isInverse = false;
4508 Instruction *AddOp = 0, *SubOp = 0;
4510 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
4511 if (TI->getOpcode() == FI->getOpcode())
4512 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
4515 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
4516 // even legal for FP.
4517 if (TI->getOpcode() == Instruction::Sub &&
4518 FI->getOpcode() == Instruction::Add) {
4519 AddOp = FI; SubOp = TI;
4520 } else if (FI->getOpcode() == Instruction::Sub &&
4521 TI->getOpcode() == Instruction::Add) {
4522 AddOp = TI; SubOp = FI;
4526 Value *OtherAddOp = 0;
4527 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
4528 OtherAddOp = AddOp->getOperand(1);
4529 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
4530 OtherAddOp = AddOp->getOperand(0);
4534 // So at this point we know we have:
4535 // select C, (add X, Y), (sub X, ?)
4536 // We can do the transform profitably if either 'Y' = '?' or '?' is
4538 if (SubOp->getOperand(1) == AddOp ||
4539 isa<Constant>(SubOp->getOperand(1))) {
4541 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
4542 NegVal = ConstantExpr::getNeg(C);
4544 NegVal = InsertNewInstBefore(
4545 BinaryOperator::createNeg(SubOp->getOperand(1)), SI);
4548 Value *NewTrueOp = OtherAddOp;
4549 Value *NewFalseOp = NegVal;
4551 std::swap(NewTrueOp, NewFalseOp);
4552 Instruction *NewSel =
4553 new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
4555 NewSel = InsertNewInstBefore(NewSel, SI);
4556 return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
4562 // See if we can fold the select into one of our operands.
4563 if (SI.getType()->isInteger()) {
4564 // See the comment above GetSelectFoldableOperands for a description of the
4565 // transformation we are doing here.
4566 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
4567 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
4568 !isa<Constant>(FalseVal))
4569 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
4570 unsigned OpToFold = 0;
4571 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
4573 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
4578 Constant *C = GetSelectFoldableConstant(TVI);
4579 std::string Name = TVI->getName(); TVI->setName("");
4580 Instruction *NewSel =
4581 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
4583 InsertNewInstBefore(NewSel, SI);
4584 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
4585 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
4586 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
4587 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
4589 assert(0 && "Unknown instruction!!");
4594 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
4595 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
4596 !isa<Constant>(TrueVal))
4597 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
4598 unsigned OpToFold = 0;
4599 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
4601 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
4606 Constant *C = GetSelectFoldableConstant(FVI);
4607 std::string Name = FVI->getName(); FVI->setName("");
4608 Instruction *NewSel =
4609 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
4611 InsertNewInstBefore(NewSel, SI);
4612 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
4613 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
4614 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
4615 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
4617 assert(0 && "Unknown instruction!!");
4623 if (BinaryOperator::isNot(CondVal)) {
4624 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
4625 SI.setOperand(1, FalseVal);
4626 SI.setOperand(2, TrueVal);
4634 /// visitCallInst - CallInst simplification. This mostly only handles folding
4635 /// of intrinsic instructions. For normal calls, it allows visitCallSite to do
4636 /// the heavy lifting.
4638 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
4639 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
4640 if (!II) return visitCallSite(&CI);
4642 // Intrinsics cannot occur in an invoke, so handle them here instead of in
4644 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
4645 bool Changed = false;
4647 // memmove/cpy/set of zero bytes is a noop.
4648 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
4649 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
4651 // FIXME: Increase alignment here.
4653 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
4654 if (CI->getRawValue() == 1) {
4655 // Replace the instruction with just byte operations. We would
4656 // transform other cases to loads/stores, but we don't know if
4657 // alignment is sufficient.
4661 // If we have a memmove and the source operation is a constant global,
4662 // then the source and dest pointers can't alias, so we can change this
4663 // into a call to memcpy.
4664 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(II))
4665 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
4666 if (GVSrc->isConstant()) {
4667 Module *M = CI.getParent()->getParent()->getParent();
4668 Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
4669 CI.getCalledFunction()->getFunctionType());
4670 CI.setOperand(0, MemCpy);
4674 if (Changed) return II;
4675 } else if (DbgStopPointInst *SPI = dyn_cast<DbgStopPointInst>(II)) {
4676 // If this stoppoint is at the same source location as the previous
4677 // stoppoint in the chain, it is not needed.
4678 if (DbgStopPointInst *PrevSPI =
4679 dyn_cast<DbgStopPointInst>(SPI->getChain()))
4680 if (SPI->getLineNo() == PrevSPI->getLineNo() &&
4681 SPI->getColNo() == PrevSPI->getColNo()) {
4682 SPI->replaceAllUsesWith(PrevSPI);
4683 return EraseInstFromFunction(CI);
4686 switch (II->getIntrinsicID()) {
4688 case Intrinsic::stackrestore: {
4689 // If the save is right next to the restore, remove the restore. This can
4690 // happen when variable allocas are DCE'd.
4691 if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
4692 if (SS->getIntrinsicID() == Intrinsic::stacksave) {
4693 BasicBlock::iterator BI = SS;
4695 return EraseInstFromFunction(CI);
4699 // If the stack restore is in a return/unwind block and if there are no
4700 // allocas or calls between the restore and the return, nuke the restore.
4701 TerminatorInst *TI = II->getParent()->getTerminator();
4702 if (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)) {
4703 BasicBlock::iterator BI = II;
4704 bool CannotRemove = false;
4705 for (++BI; &*BI != TI; ++BI) {
4706 if (isa<AllocaInst>(BI) ||
4707 (isa<CallInst>(BI) && !isa<IntrinsicInst>(BI))) {
4708 CannotRemove = true;
4713 return EraseInstFromFunction(CI);
4720 return visitCallSite(II);
4723 // InvokeInst simplification
4725 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
4726 return visitCallSite(&II);
4729 // visitCallSite - Improvements for call and invoke instructions.
4731 Instruction *InstCombiner::visitCallSite(CallSite CS) {
4732 bool Changed = false;
4734 // If the callee is a constexpr cast of a function, attempt to move the cast
4735 // to the arguments of the call/invoke.
4736 if (transformConstExprCastCall(CS)) return 0;
4738 Value *Callee = CS.getCalledValue();
4740 if (Function *CalleeF = dyn_cast<Function>(Callee))
4741 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
4742 Instruction *OldCall = CS.getInstruction();
4743 // If the call and callee calling conventions don't match, this call must
4744 // be unreachable, as the call is undefined.
4745 new StoreInst(ConstantBool::True,
4746 UndefValue::get(PointerType::get(Type::BoolTy)), OldCall);
4747 if (!OldCall->use_empty())
4748 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
4749 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
4750 return EraseInstFromFunction(*OldCall);
4754 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
4755 // This instruction is not reachable, just remove it. We insert a store to
4756 // undef so that we know that this code is not reachable, despite the fact
4757 // that we can't modify the CFG here.
4758 new StoreInst(ConstantBool::True,
4759 UndefValue::get(PointerType::get(Type::BoolTy)),
4760 CS.getInstruction());
4762 if (!CS.getInstruction()->use_empty())
4763 CS.getInstruction()->
4764 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
4766 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
4767 // Don't break the CFG, insert a dummy cond branch.
4768 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
4769 ConstantBool::True, II);
4771 return EraseInstFromFunction(*CS.getInstruction());
4774 const PointerType *PTy = cast<PointerType>(Callee->getType());
4775 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
4776 if (FTy->isVarArg()) {
4777 // See if we can optimize any arguments passed through the varargs area of
4779 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
4780 E = CS.arg_end(); I != E; ++I)
4781 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
4782 // If this cast does not effect the value passed through the varargs
4783 // area, we can eliminate the use of the cast.
4784 Value *Op = CI->getOperand(0);
4785 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
4792 return Changed ? CS.getInstruction() : 0;
4795 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
4796 // attempt to move the cast to the arguments of the call/invoke.
4798 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
4799 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
4800 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
4801 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
4803 Function *Callee = cast<Function>(CE->getOperand(0));
4804 Instruction *Caller = CS.getInstruction();
4806 // Okay, this is a cast from a function to a different type. Unless doing so
4807 // would cause a type conversion of one of our arguments, change this call to
4808 // be a direct call with arguments casted to the appropriate types.
4810 const FunctionType *FT = Callee->getFunctionType();
4811 const Type *OldRetTy = Caller->getType();
4813 // Check to see if we are changing the return type...
4814 if (OldRetTy != FT->getReturnType()) {
4815 if (Callee->isExternal() &&
4816 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
4817 !Caller->use_empty())
4818 return false; // Cannot transform this return value...
4820 // If the callsite is an invoke instruction, and the return value is used by
4821 // a PHI node in a successor, we cannot change the return type of the call
4822 // because there is no place to put the cast instruction (without breaking
4823 // the critical edge). Bail out in this case.
4824 if (!Caller->use_empty())
4825 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
4826 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
4828 if (PHINode *PN = dyn_cast<PHINode>(*UI))
4829 if (PN->getParent() == II->getNormalDest() ||
4830 PN->getParent() == II->getUnwindDest())
4834 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
4835 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
4837 CallSite::arg_iterator AI = CS.arg_begin();
4838 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
4839 const Type *ParamTy = FT->getParamType(i);
4840 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
4841 if (Callee->isExternal() && !isConvertible) return false;
4844 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
4845 Callee->isExternal())
4846 return false; // Do not delete arguments unless we have a function body...
4848 // Okay, we decided that this is a safe thing to do: go ahead and start
4849 // inserting cast instructions as necessary...
4850 std::vector<Value*> Args;
4851 Args.reserve(NumActualArgs);
4853 AI = CS.arg_begin();
4854 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
4855 const Type *ParamTy = FT->getParamType(i);
4856 if ((*AI)->getType() == ParamTy) {
4857 Args.push_back(*AI);
4859 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
4864 // If the function takes more arguments than the call was taking, add them
4866 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
4867 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
4869 // If we are removing arguments to the function, emit an obnoxious warning...
4870 if (FT->getNumParams() < NumActualArgs)
4871 if (!FT->isVarArg()) {
4872 std::cerr << "WARNING: While resolving call to function '"
4873 << Callee->getName() << "' arguments were dropped!\n";
4875 // Add all of the arguments in their promoted form to the arg list...
4876 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
4877 const Type *PTy = getPromotedType((*AI)->getType());
4878 if (PTy != (*AI)->getType()) {
4879 // Must promote to pass through va_arg area!
4880 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
4881 InsertNewInstBefore(Cast, *Caller);
4882 Args.push_back(Cast);
4884 Args.push_back(*AI);
4889 if (FT->getReturnType() == Type::VoidTy)
4890 Caller->setName(""); // Void type should not have a name...
4893 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4894 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
4895 Args, Caller->getName(), Caller);
4896 cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
4898 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
4899 if (cast<CallInst>(Caller)->isTailCall())
4900 cast<CallInst>(NC)->setTailCall();
4901 cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
4904 // Insert a cast of the return type as necessary...
4906 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
4907 if (NV->getType() != Type::VoidTy) {
4908 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
4910 // If this is an invoke instruction, we should insert it after the first
4911 // non-phi, instruction in the normal successor block.
4912 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4913 BasicBlock::iterator I = II->getNormalDest()->begin();
4914 while (isa<PHINode>(I)) ++I;
4915 InsertNewInstBefore(NC, *I);
4917 // Otherwise, it's a call, just insert cast right after the call instr
4918 InsertNewInstBefore(NC, *Caller);
4920 AddUsersToWorkList(*Caller);
4922 NV = UndefValue::get(Caller->getType());
4926 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
4927 Caller->replaceAllUsesWith(NV);
4928 Caller->getParent()->getInstList().erase(Caller);
4929 removeFromWorkList(Caller);
4934 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
4935 // operator and they all are only used by the PHI, PHI together their
4936 // inputs, and do the operation once, to the result of the PHI.
4937 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
4938 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
4940 // Scan the instruction, looking for input operations that can be folded away.
4941 // If all input operands to the phi are the same instruction (e.g. a cast from
4942 // the same type or "+42") we can pull the operation through the PHI, reducing
4943 // code size and simplifying code.
4944 Constant *ConstantOp = 0;
4945 const Type *CastSrcTy = 0;
4946 if (isa<CastInst>(FirstInst)) {
4947 CastSrcTy = FirstInst->getOperand(0)->getType();
4948 } else if (isa<BinaryOperator>(FirstInst) || isa<ShiftInst>(FirstInst)) {
4949 // Can fold binop or shift if the RHS is a constant.
4950 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
4951 if (ConstantOp == 0) return 0;
4953 return 0; // Cannot fold this operation.
4956 // Check to see if all arguments are the same operation.
4957 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4958 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
4959 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
4960 if (!I->hasOneUse() || I->getOpcode() != FirstInst->getOpcode())
4963 if (I->getOperand(0)->getType() != CastSrcTy)
4964 return 0; // Cast operation must match.
4965 } else if (I->getOperand(1) != ConstantOp) {
4970 // Okay, they are all the same operation. Create a new PHI node of the
4971 // correct type, and PHI together all of the LHS's of the instructions.
4972 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
4973 PN.getName()+".in");
4974 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
4976 Value *InVal = FirstInst->getOperand(0);
4977 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
4979 // Add all operands to the new PHI.
4980 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4981 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
4982 if (NewInVal != InVal)
4984 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
4989 // The new PHI unions all of the same values together. This is really
4990 // common, so we handle it intelligently here for compile-time speed.
4994 InsertNewInstBefore(NewPN, PN);
4998 // Insert and return the new operation.
4999 if (isa<CastInst>(FirstInst))
5000 return new CastInst(PhiVal, PN.getType());
5001 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
5002 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
5004 return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(),
5005 PhiVal, ConstantOp);
5008 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
5010 static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &PotentiallyDeadPHIs) {
5011 if (PN->use_empty()) return true;
5012 if (!PN->hasOneUse()) return false;
5014 // Remember this node, and if we find the cycle, return.
5015 if (!PotentiallyDeadPHIs.insert(PN).second)
5018 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
5019 return DeadPHICycle(PU, PotentiallyDeadPHIs);
5024 // PHINode simplification
5026 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
5027 if (Value *V = PN.hasConstantValue())
5028 return ReplaceInstUsesWith(PN, V);
5030 // If the only user of this instruction is a cast instruction, and all of the
5031 // incoming values are constants, change this PHI to merge together the casted
5034 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
5035 if (CI->getType() != PN.getType()) { // noop casts will be folded
5036 bool AllConstant = true;
5037 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
5038 if (!isa<Constant>(PN.getIncomingValue(i))) {
5039 AllConstant = false;
5043 // Make a new PHI with all casted values.
5044 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
5045 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
5046 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
5047 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
5048 PN.getIncomingBlock(i));
5051 // Update the cast instruction.
5052 CI->setOperand(0, New);
5053 WorkList.push_back(CI); // revisit the cast instruction to fold.
5054 WorkList.push_back(New); // Make sure to revisit the new Phi
5055 return &PN; // PN is now dead!
5059 // If all PHI operands are the same operation, pull them through the PHI,
5060 // reducing code size.
5061 if (isa<Instruction>(PN.getIncomingValue(0)) &&
5062 PN.getIncomingValue(0)->hasOneUse())
5063 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
5066 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
5067 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
5068 // PHI)... break the cycle.
5070 if (PHINode *PU = dyn_cast<PHINode>(PN.use_back())) {
5071 std::set<PHINode*> PotentiallyDeadPHIs;
5072 PotentiallyDeadPHIs.insert(&PN);
5073 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
5074 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
5080 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
5081 Instruction *InsertPoint,
5083 unsigned PS = IC->getTargetData().getPointerSize();
5084 const Type *VTy = V->getType();
5085 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
5086 // We must insert a cast to ensure we sign-extend.
5087 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
5088 V->getName()), *InsertPoint);
5089 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
5094 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
5095 Value *PtrOp = GEP.getOperand(0);
5096 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
5097 // If so, eliminate the noop.
5098 if (GEP.getNumOperands() == 1)
5099 return ReplaceInstUsesWith(GEP, PtrOp);
5101 if (isa<UndefValue>(GEP.getOperand(0)))
5102 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
5104 bool HasZeroPointerIndex = false;
5105 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
5106 HasZeroPointerIndex = C->isNullValue();
5108 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
5109 return ReplaceInstUsesWith(GEP, PtrOp);
5111 // Eliminate unneeded casts for indices.
5112 bool MadeChange = false;
5113 gep_type_iterator GTI = gep_type_begin(GEP);
5114 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
5115 if (isa<SequentialType>(*GTI)) {
5116 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
5117 Value *Src = CI->getOperand(0);
5118 const Type *SrcTy = Src->getType();
5119 const Type *DestTy = CI->getType();
5120 if (Src->getType()->isInteger()) {
5121 if (SrcTy->getPrimitiveSizeInBits() ==
5122 DestTy->getPrimitiveSizeInBits()) {
5123 // We can always eliminate a cast from ulong or long to the other.
5124 // We can always eliminate a cast from uint to int or the other on
5125 // 32-bit pointer platforms.
5126 if (DestTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()){
5128 GEP.setOperand(i, Src);
5130 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
5131 SrcTy->getPrimitiveSize() == 4) {
5132 // We can always eliminate a cast from int to [u]long. We can
5133 // eliminate a cast from uint to [u]long iff the target is a 32-bit
5135 if (SrcTy->isSigned() ||
5136 SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
5138 GEP.setOperand(i, Src);
5143 // If we are using a wider index than needed for this platform, shrink it
5144 // to what we need. If the incoming value needs a cast instruction,
5145 // insert it. This explicit cast can make subsequent optimizations more
5147 Value *Op = GEP.getOperand(i);
5148 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
5149 if (Constant *C = dyn_cast<Constant>(Op)) {
5150 GEP.setOperand(i, ConstantExpr::getCast(C,
5151 TD->getIntPtrType()->getSignedVersion()));
5154 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
5155 Op->getName()), GEP);
5156 GEP.setOperand(i, Op);
5160 // If this is a constant idx, make sure to canonicalize it to be a signed
5161 // operand, otherwise CSE and other optimizations are pessimized.
5162 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
5163 GEP.setOperand(i, ConstantExpr::getCast(CUI,
5164 CUI->getType()->getSignedVersion()));
5168 if (MadeChange) return &GEP;
5170 // Combine Indices - If the source pointer to this getelementptr instruction
5171 // is a getelementptr instruction, combine the indices of the two
5172 // getelementptr instructions into a single instruction.
5174 std::vector<Value*> SrcGEPOperands;
5175 if (User *Src = dyn_castGetElementPtr(PtrOp))
5176 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
5178 if (!SrcGEPOperands.empty()) {
5179 // Note that if our source is a gep chain itself that we wait for that
5180 // chain to be resolved before we perform this transformation. This
5181 // avoids us creating a TON of code in some cases.
5183 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
5184 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
5185 return 0; // Wait until our source is folded to completion.
5187 std::vector<Value *> Indices;
5189 // Find out whether the last index in the source GEP is a sequential idx.
5190 bool EndsWithSequential = false;
5191 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
5192 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
5193 EndsWithSequential = !isa<StructType>(*I);
5195 // Can we combine the two pointer arithmetics offsets?
5196 if (EndsWithSequential) {
5197 // Replace: gep (gep %P, long B), long A, ...
5198 // With: T = long A+B; gep %P, T, ...
5200 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
5201 if (SO1 == Constant::getNullValue(SO1->getType())) {
5203 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
5206 // If they aren't the same type, convert both to an integer of the
5207 // target's pointer size.
5208 if (SO1->getType() != GO1->getType()) {
5209 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
5210 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
5211 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
5212 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
5214 unsigned PS = TD->getPointerSize();
5215 if (SO1->getType()->getPrimitiveSize() == PS) {
5216 // Convert GO1 to SO1's type.
5217 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
5219 } else if (GO1->getType()->getPrimitiveSize() == PS) {
5220 // Convert SO1 to GO1's type.
5221 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
5223 const Type *PT = TD->getIntPtrType();
5224 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
5225 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
5229 if (isa<Constant>(SO1) && isa<Constant>(GO1))
5230 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
5232 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
5233 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
5237 // Recycle the GEP we already have if possible.
5238 if (SrcGEPOperands.size() == 2) {
5239 GEP.setOperand(0, SrcGEPOperands[0]);
5240 GEP.setOperand(1, Sum);
5243 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
5244 SrcGEPOperands.end()-1);
5245 Indices.push_back(Sum);
5246 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
5248 } else if (isa<Constant>(*GEP.idx_begin()) &&
5249 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
5250 SrcGEPOperands.size() != 1) {
5251 // Otherwise we can do the fold if the first index of the GEP is a zero
5252 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
5253 SrcGEPOperands.end());
5254 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
5257 if (!Indices.empty())
5258 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
5260 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
5261 // GEP of global variable. If all of the indices for this GEP are
5262 // constants, we can promote this to a constexpr instead of an instruction.
5264 // Scan for nonconstants...
5265 std::vector<Constant*> Indices;
5266 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
5267 for (; I != E && isa<Constant>(*I); ++I)
5268 Indices.push_back(cast<Constant>(*I));
5270 if (I == E) { // If they are all constants...
5271 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
5273 // Replace all uses of the GEP with the new constexpr...
5274 return ReplaceInstUsesWith(GEP, CE);
5276 } else if (Value *X = isCast(PtrOp)) { // Is the operand a cast?
5277 if (!isa<PointerType>(X->getType())) {
5278 // Not interesting. Source pointer must be a cast from pointer.
5279 } else if (HasZeroPointerIndex) {
5280 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
5281 // into : GEP [10 x ubyte]* X, long 0, ...
5283 // This occurs when the program declares an array extern like "int X[];"
5285 const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
5286 const PointerType *XTy = cast<PointerType>(X->getType());
5287 if (const ArrayType *XATy =
5288 dyn_cast<ArrayType>(XTy->getElementType()))
5289 if (const ArrayType *CATy =
5290 dyn_cast<ArrayType>(CPTy->getElementType()))
5291 if (CATy->getElementType() == XATy->getElementType()) {
5292 // At this point, we know that the cast source type is a pointer
5293 // to an array of the same type as the destination pointer
5294 // array. Because the array type is never stepped over (there
5295 // is a leading zero) we can fold the cast into this GEP.
5296 GEP.setOperand(0, X);
5299 } else if (GEP.getNumOperands() == 2) {
5300 // Transform things like:
5301 // %t = getelementptr ubyte* cast ([2 x int]* %str to uint*), uint %V
5302 // into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast
5303 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
5304 const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
5305 if (isa<ArrayType>(SrcElTy) &&
5306 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
5307 TD->getTypeSize(ResElTy)) {
5308 Value *V = InsertNewInstBefore(
5309 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
5310 GEP.getOperand(1), GEP.getName()), GEP);
5311 return new CastInst(V, GEP.getType());
5314 // Transform things like:
5315 // getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp
5316 // (where tmp = 8*tmp2) into:
5317 // getelementptr [100 x double]* %arr, int 0, int %tmp.2
5319 if (isa<ArrayType>(SrcElTy) &&
5320 (ResElTy == Type::SByteTy || ResElTy == Type::UByteTy)) {
5321 uint64_t ArrayEltSize =
5322 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType());
5324 // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
5325 // allow either a mul, shift, or constant here.
5327 ConstantInt *Scale = 0;
5328 if (ArrayEltSize == 1) {
5329 NewIdx = GEP.getOperand(1);
5330 Scale = ConstantInt::get(NewIdx->getType(), 1);
5331 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
5332 NewIdx = ConstantInt::get(CI->getType(), 1);
5334 } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
5335 if (Inst->getOpcode() == Instruction::Shl &&
5336 isa<ConstantInt>(Inst->getOperand(1))) {
5337 unsigned ShAmt =cast<ConstantUInt>(Inst->getOperand(1))->getValue();
5338 if (Inst->getType()->isSigned())
5339 Scale = ConstantSInt::get(Inst->getType(), 1ULL << ShAmt);
5341 Scale = ConstantUInt::get(Inst->getType(), 1ULL << ShAmt);
5342 NewIdx = Inst->getOperand(0);
5343 } else if (Inst->getOpcode() == Instruction::Mul &&
5344 isa<ConstantInt>(Inst->getOperand(1))) {
5345 Scale = cast<ConstantInt>(Inst->getOperand(1));
5346 NewIdx = Inst->getOperand(0);
5350 // If the index will be to exactly the right offset with the scale taken
5351 // out, perform the transformation.
5352 if (Scale && Scale->getRawValue() % ArrayEltSize == 0) {
5353 if (ConstantSInt *C = dyn_cast<ConstantSInt>(Scale))
5354 Scale = ConstantSInt::get(C->getType(),
5355 (int64_t)C->getRawValue() /
5356 (int64_t)ArrayEltSize);
5358 Scale = ConstantUInt::get(Scale->getType(),
5359 Scale->getRawValue() / ArrayEltSize);
5360 if (Scale->getRawValue() != 1) {
5361 Constant *C = ConstantExpr::getCast(Scale, NewIdx->getType());
5362 Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale");
5363 NewIdx = InsertNewInstBefore(Sc, GEP);
5366 // Insert the new GEP instruction.
5368 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
5369 NewIdx, GEP.getName());
5370 Idx = InsertNewInstBefore(Idx, GEP);
5371 return new CastInst(Idx, GEP.getType());
5380 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
5381 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
5382 if (AI.isArrayAllocation()) // Check C != 1
5383 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
5384 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
5385 AllocationInst *New = 0;
5387 // Create and insert the replacement instruction...
5388 if (isa<MallocInst>(AI))
5389 New = new MallocInst(NewTy, 0, AI.getAlignment(), AI.getName());
5391 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
5392 New = new AllocaInst(NewTy, 0, AI.getAlignment(), AI.getName());
5395 InsertNewInstBefore(New, AI);
5397 // Scan to the end of the allocation instructions, to skip over a block of
5398 // allocas if possible...
5400 BasicBlock::iterator It = New;
5401 while (isa<AllocationInst>(*It)) ++It;
5403 // Now that I is pointing to the first non-allocation-inst in the block,
5404 // insert our getelementptr instruction...
5406 Value *NullIdx = Constant::getNullValue(Type::IntTy);
5407 Value *V = new GetElementPtrInst(New, NullIdx, NullIdx,
5408 New->getName()+".sub", It);
5410 // Now make everything use the getelementptr instead of the original
5412 return ReplaceInstUsesWith(AI, V);
5413 } else if (isa<UndefValue>(AI.getArraySize())) {
5414 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5417 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
5418 // Note that we only do this for alloca's, because malloc should allocate and
5419 // return a unique pointer, even for a zero byte allocation.
5420 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
5421 TD->getTypeSize(AI.getAllocatedType()) == 0)
5422 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5427 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
5428 Value *Op = FI.getOperand(0);
5430 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
5431 if (CastInst *CI = dyn_cast<CastInst>(Op))
5432 if (isa<PointerType>(CI->getOperand(0)->getType())) {
5433 FI.setOperand(0, CI->getOperand(0));
5437 // free undef -> unreachable.
5438 if (isa<UndefValue>(Op)) {
5439 // Insert a new store to null because we cannot modify the CFG here.
5440 new StoreInst(ConstantBool::True,
5441 UndefValue::get(PointerType::get(Type::BoolTy)), &FI);
5442 return EraseInstFromFunction(FI);
5445 // If we have 'free null' delete the instruction. This can happen in stl code
5446 // when lots of inlining happens.
5447 if (isa<ConstantPointerNull>(Op))
5448 return EraseInstFromFunction(FI);
5454 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
5455 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
5456 User *CI = cast<User>(LI.getOperand(0));
5457 Value *CastOp = CI->getOperand(0);
5459 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5460 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5461 const Type *SrcPTy = SrcTy->getElementType();
5463 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5464 // If the source is an array, the code below will not succeed. Check to
5465 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5467 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5468 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5469 if (ASrcTy->getNumElements() != 0) {
5470 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5471 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5472 SrcTy = cast<PointerType>(CastOp->getType());
5473 SrcPTy = SrcTy->getElementType();
5476 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5477 // Do not allow turning this into a load of an integer, which is then
5478 // casted to a pointer, this pessimizes pointer analysis a lot.
5479 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
5480 IC.getTargetData().getTypeSize(SrcPTy) ==
5481 IC.getTargetData().getTypeSize(DestPTy)) {
5483 // Okay, we are casting from one integer or pointer type to another of
5484 // the same size. Instead of casting the pointer before the load, cast
5485 // the result of the loaded value.
5486 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
5488 LI.isVolatile()),LI);
5489 // Now cast the result of the load.
5490 return new CastInst(NewLoad, LI.getType());
5497 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
5498 /// from this value cannot trap. If it is not obviously safe to load from the
5499 /// specified pointer, we do a quick local scan of the basic block containing
5500 /// ScanFrom, to determine if the address is already accessed.
5501 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
5502 // If it is an alloca or global variable, it is always safe to load from.
5503 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
5505 // Otherwise, be a little bit agressive by scanning the local block where we
5506 // want to check to see if the pointer is already being loaded or stored
5507 // from/to. If so, the previous load or store would have already trapped,
5508 // so there is no harm doing an extra load (also, CSE will later eliminate
5509 // the load entirely).
5510 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
5515 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
5516 if (LI->getOperand(0) == V) return true;
5517 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
5518 if (SI->getOperand(1) == V) return true;
5524 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
5525 Value *Op = LI.getOperand(0);
5527 // load (cast X) --> cast (load X) iff safe
5528 if (CastInst *CI = dyn_cast<CastInst>(Op))
5529 if (Instruction *Res = InstCombineLoadCast(*this, LI))
5532 // None of the following transforms are legal for volatile loads.
5533 if (LI.isVolatile()) return 0;
5535 if (&LI.getParent()->front() != &LI) {
5536 BasicBlock::iterator BBI = &LI; --BBI;
5537 // If the instruction immediately before this is a store to the same
5538 // address, do a simple form of store->load forwarding.
5539 if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
5540 if (SI->getOperand(1) == LI.getOperand(0))
5541 return ReplaceInstUsesWith(LI, SI->getOperand(0));
5542 if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
5543 if (LIB->getOperand(0) == LI.getOperand(0))
5544 return ReplaceInstUsesWith(LI, LIB);
5547 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
5548 if (isa<ConstantPointerNull>(GEPI->getOperand(0)) ||
5549 isa<UndefValue>(GEPI->getOperand(0))) {
5550 // Insert a new store to null instruction before the load to indicate
5551 // that this code is not reachable. We do this instead of inserting
5552 // an unreachable instruction directly because we cannot modify the
5554 new StoreInst(UndefValue::get(LI.getType()),
5555 Constant::getNullValue(Op->getType()), &LI);
5556 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5559 if (Constant *C = dyn_cast<Constant>(Op)) {
5560 // load null/undef -> undef
5561 if ((C->isNullValue() || isa<UndefValue>(C))) {
5562 // Insert a new store to null instruction before the load to indicate that
5563 // this code is not reachable. We do this instead of inserting an
5564 // unreachable instruction directly because we cannot modify the CFG.
5565 new StoreInst(UndefValue::get(LI.getType()),
5566 Constant::getNullValue(Op->getType()), &LI);
5567 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5570 // Instcombine load (constant global) into the value loaded.
5571 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
5572 if (GV->isConstant() && !GV->isExternal())
5573 return ReplaceInstUsesWith(LI, GV->getInitializer());
5575 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
5576 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
5577 if (CE->getOpcode() == Instruction::GetElementPtr) {
5578 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
5579 if (GV->isConstant() && !GV->isExternal())
5581 ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
5582 return ReplaceInstUsesWith(LI, V);
5583 if (CE->getOperand(0)->isNullValue()) {
5584 // Insert a new store to null instruction before the load to indicate
5585 // that this code is not reachable. We do this instead of inserting
5586 // an unreachable instruction directly because we cannot modify the
5588 new StoreInst(UndefValue::get(LI.getType()),
5589 Constant::getNullValue(Op->getType()), &LI);
5590 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5593 } else if (CE->getOpcode() == Instruction::Cast) {
5594 if (Instruction *Res = InstCombineLoadCast(*this, LI))
5599 if (Op->hasOneUse()) {
5600 // Change select and PHI nodes to select values instead of addresses: this
5601 // helps alias analysis out a lot, allows many others simplifications, and
5602 // exposes redundancy in the code.
5604 // Note that we cannot do the transformation unless we know that the
5605 // introduced loads cannot trap! Something like this is valid as long as
5606 // the condition is always false: load (select bool %C, int* null, int* %G),
5607 // but it would not be valid if we transformed it to load from null
5610 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
5611 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
5612 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
5613 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
5614 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
5615 SI->getOperand(1)->getName()+".val"), LI);
5616 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
5617 SI->getOperand(2)->getName()+".val"), LI);
5618 return new SelectInst(SI->getCondition(), V1, V2);
5621 // load (select (cond, null, P)) -> load P
5622 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
5623 if (C->isNullValue()) {
5624 LI.setOperand(0, SI->getOperand(2));
5628 // load (select (cond, P, null)) -> load P
5629 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
5630 if (C->isNullValue()) {
5631 LI.setOperand(0, SI->getOperand(1));
5635 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
5636 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
5637 bool Safe = PN->getParent() == LI.getParent();
5639 // Scan all of the instructions between the PHI and the load to make
5640 // sure there are no instructions that might possibly alter the value
5641 // loaded from the PHI.
5643 BasicBlock::iterator I = &LI;
5644 for (--I; !isa<PHINode>(I); --I)
5645 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
5651 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
5652 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
5653 PN->getIncomingBlock(i)->getTerminator()))
5658 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
5659 InsertNewInstBefore(NewPN, *PN);
5660 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
5662 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
5663 BasicBlock *BB = PN->getIncomingBlock(i);
5664 Value *&TheLoad = LoadMap[BB];
5666 Value *InVal = PN->getIncomingValue(i);
5667 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
5668 InVal->getName()+".val"),
5669 *BB->getTerminator());
5671 NewPN->addIncoming(TheLoad, BB);
5673 return ReplaceInstUsesWith(LI, NewPN);
5680 /// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store (cast V), P'
5682 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
5683 User *CI = cast<User>(SI.getOperand(1));
5684 Value *CastOp = CI->getOperand(0);
5686 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5687 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5688 const Type *SrcPTy = SrcTy->getElementType();
5690 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5691 // If the source is an array, the code below will not succeed. Check to
5692 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5694 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5695 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5696 if (ASrcTy->getNumElements() != 0) {
5697 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5698 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5699 SrcTy = cast<PointerType>(CastOp->getType());
5700 SrcPTy = SrcTy->getElementType();
5703 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5704 IC.getTargetData().getTypeSize(SrcPTy) ==
5705 IC.getTargetData().getTypeSize(DestPTy)) {
5707 // Okay, we are casting from one integer or pointer type to another of
5708 // the same size. Instead of casting the pointer before the store, cast
5709 // the value to be stored.
5711 if (Constant *C = dyn_cast<Constant>(SI.getOperand(0)))
5712 NewCast = ConstantExpr::getCast(C, SrcPTy);
5714 NewCast = IC.InsertNewInstBefore(new CastInst(SI.getOperand(0),
5716 SI.getOperand(0)->getName()+".c"), SI);
5718 return new StoreInst(NewCast, CastOp);
5725 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
5726 Value *Val = SI.getOperand(0);
5727 Value *Ptr = SI.getOperand(1);
5729 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
5730 removeFromWorkList(&SI);
5731 SI.eraseFromParent();
5736 if (SI.isVolatile()) return 0; // Don't hack volatile loads.
5738 // store X, null -> turns into 'unreachable' in SimplifyCFG
5739 if (isa<ConstantPointerNull>(Ptr)) {
5740 if (!isa<UndefValue>(Val)) {
5741 SI.setOperand(0, UndefValue::get(Val->getType()));
5742 if (Instruction *U = dyn_cast<Instruction>(Val))
5743 WorkList.push_back(U); // Dropped a use.
5746 return 0; // Do not modify these!
5749 // store undef, Ptr -> noop
5750 if (isa<UndefValue>(Val)) {
5751 removeFromWorkList(&SI);
5752 SI.eraseFromParent();
5757 // If the pointer destination is a cast, see if we can fold the cast into the
5759 if (CastInst *CI = dyn_cast<CastInst>(Ptr))
5760 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5762 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
5763 if (CE->getOpcode() == Instruction::Cast)
5764 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5768 // If this store is the last instruction in the basic block, and if the block
5769 // ends with an unconditional branch, try to move it to the successor block.
5770 BasicBlock::iterator BBI = &SI; ++BBI;
5771 if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
5772 if (BI->isUnconditional()) {
5773 // Check to see if the successor block has exactly two incoming edges. If
5774 // so, see if the other predecessor contains a store to the same location.
5775 // if so, insert a PHI node (if needed) and move the stores down.
5776 BasicBlock *Dest = BI->getSuccessor(0);
5778 pred_iterator PI = pred_begin(Dest);
5779 BasicBlock *Other = 0;
5780 if (*PI != BI->getParent())
5783 if (PI != pred_end(Dest)) {
5784 if (*PI != BI->getParent())
5789 if (++PI != pred_end(Dest))
5792 if (Other) { // If only one other pred...
5793 BBI = Other->getTerminator();
5794 // Make sure this other block ends in an unconditional branch and that
5795 // there is an instruction before the branch.
5796 if (isa<BranchInst>(BBI) && cast<BranchInst>(BBI)->isUnconditional() &&
5797 BBI != Other->begin()) {
5799 StoreInst *OtherStore = dyn_cast<StoreInst>(BBI);
5801 // If this instruction is a store to the same location.
5802 if (OtherStore && OtherStore->getOperand(1) == SI.getOperand(1)) {
5803 // Okay, we know we can perform this transformation. Insert a PHI
5804 // node now if we need it.
5805 Value *MergedVal = OtherStore->getOperand(0);
5806 if (MergedVal != SI.getOperand(0)) {
5807 PHINode *PN = new PHINode(MergedVal->getType(), "storemerge");
5808 PN->reserveOperandSpace(2);
5809 PN->addIncoming(SI.getOperand(0), SI.getParent());
5810 PN->addIncoming(OtherStore->getOperand(0), Other);
5811 MergedVal = InsertNewInstBefore(PN, Dest->front());
5814 // Advance to a place where it is safe to insert the new store and
5816 BBI = Dest->begin();
5817 while (isa<PHINode>(BBI)) ++BBI;
5818 InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
5819 OtherStore->isVolatile()), *BBI);
5821 // Nuke the old stores.
5822 removeFromWorkList(&SI);
5823 removeFromWorkList(OtherStore);
5824 SI.eraseFromParent();
5825 OtherStore->eraseFromParent();
5837 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
5838 // Change br (not X), label True, label False to: br X, label False, True
5840 BasicBlock *TrueDest;
5841 BasicBlock *FalseDest;
5842 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
5843 !isa<Constant>(X)) {
5844 // Swap Destinations and condition...
5846 BI.setSuccessor(0, FalseDest);
5847 BI.setSuccessor(1, TrueDest);
5851 // Cannonicalize setne -> seteq
5852 Instruction::BinaryOps Op; Value *Y;
5853 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
5854 TrueDest, FalseDest)))
5855 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
5856 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
5857 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
5858 std::string Name = I->getName(); I->setName("");
5859 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
5860 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
5861 // Swap Destinations and condition...
5862 BI.setCondition(NewSCC);
5863 BI.setSuccessor(0, FalseDest);
5864 BI.setSuccessor(1, TrueDest);
5865 removeFromWorkList(I);
5866 I->getParent()->getInstList().erase(I);
5867 WorkList.push_back(cast<Instruction>(NewSCC));
5874 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
5875 Value *Cond = SI.getCondition();
5876 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
5877 if (I->getOpcode() == Instruction::Add)
5878 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
5879 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
5880 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
5881 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
5883 SI.setOperand(0, I->getOperand(0));
5884 WorkList.push_back(I);
5891 Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
5892 if (ConstantAggregateZero *C =
5893 dyn_cast<ConstantAggregateZero>(EI.getOperand(0))) {
5894 // If packed val is constant 0, replace extract with scalar 0
5895 const Type *Ty = cast<PackedType>(C->getType())->getElementType();
5896 EI.replaceAllUsesWith(Constant::getNullValue(Ty));
5897 return ReplaceInstUsesWith(EI, Constant::getNullValue(Ty));
5899 if (ConstantPacked *C = dyn_cast<ConstantPacked>(EI.getOperand(0))) {
5900 // If packed val is constant with uniform operands, replace EI
5901 // with that operand
5902 Constant *op0 = cast<Constant>(C->getOperand(0));
5903 for (unsigned i = 1; i < C->getNumOperands(); ++i)
5904 if (C->getOperand(i) != op0) return 0;
5905 return ReplaceInstUsesWith(EI, op0);
5907 if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0)))
5908 if (I->hasOneUse()) {
5909 // Push extractelement into predecessor operation if legal and
5910 // profitable to do so
5911 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
5912 if (!isa<Constant>(BO->getOperand(0)) &&
5913 !isa<Constant>(BO->getOperand(1)))
5915 ExtractElementInst *newEI0 =
5916 new ExtractElementInst(BO->getOperand(0), EI.getOperand(1),
5918 ExtractElementInst *newEI1 =
5919 new ExtractElementInst(BO->getOperand(1), EI.getOperand(1),
5921 InsertNewInstBefore(newEI0, EI);
5922 InsertNewInstBefore(newEI1, EI);
5923 return BinaryOperator::create(BO->getOpcode(), newEI0, newEI1);
5925 switch(I->getOpcode()) {
5926 case Instruction::Load: {
5927 Value *Ptr = InsertCastBefore(I->getOperand(0),
5928 PointerType::get(EI.getType()), EI);
5929 GetElementPtrInst *GEP =
5930 new GetElementPtrInst(Ptr, EI.getOperand(1),
5931 I->getName() + ".gep");
5932 InsertNewInstBefore(GEP, EI);
5933 return new LoadInst(GEP);
5943 void InstCombiner::removeFromWorkList(Instruction *I) {
5944 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
5949 /// TryToSinkInstruction - Try to move the specified instruction from its
5950 /// current block into the beginning of DestBlock, which can only happen if it's
5951 /// safe to move the instruction past all of the instructions between it and the
5952 /// end of its block.
5953 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
5954 assert(I->hasOneUse() && "Invariants didn't hold!");
5956 // Cannot move control-flow-involving, volatile loads, vaarg, etc.
5957 if (isa<PHINode>(I) || I->mayWriteToMemory()) return false;
5959 // Do not sink alloca instructions out of the entry block.
5960 if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front())
5963 // We can only sink load instructions if there is nothing between the load and
5964 // the end of block that could change the value.
5965 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
5966 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
5968 if (Scan->mayWriteToMemory())
5972 BasicBlock::iterator InsertPos = DestBlock->begin();
5973 while (isa<PHINode>(InsertPos)) ++InsertPos;
5975 I->moveBefore(InsertPos);
5980 bool InstCombiner::runOnFunction(Function &F) {
5981 bool Changed = false;
5982 TD = &getAnalysis<TargetData>();
5985 // Populate the worklist with the reachable instructions.
5986 std::set<BasicBlock*> Visited;
5987 for (df_ext_iterator<BasicBlock*> BB = df_ext_begin(&F.front(), Visited),
5988 E = df_ext_end(&F.front(), Visited); BB != E; ++BB)
5989 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
5990 WorkList.push_back(I);
5992 // Do a quick scan over the function. If we find any blocks that are
5993 // unreachable, remove any instructions inside of them. This prevents
5994 // the instcombine code from having to deal with some bad special cases.
5995 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
5996 if (!Visited.count(BB)) {
5997 Instruction *Term = BB->getTerminator();
5998 while (Term != BB->begin()) { // Remove instrs bottom-up
5999 BasicBlock::iterator I = Term; --I;
6001 DEBUG(std::cerr << "IC: DCE: " << *I);
6004 if (!I->use_empty())
6005 I->replaceAllUsesWith(UndefValue::get(I->getType()));
6006 I->eraseFromParent();
6011 while (!WorkList.empty()) {
6012 Instruction *I = WorkList.back(); // Get an instruction from the worklist
6013 WorkList.pop_back();
6015 // Check to see if we can DCE or ConstantPropagate the instruction...
6016 // Check to see if we can DIE the instruction...
6017 if (isInstructionTriviallyDead(I)) {
6018 // Add operands to the worklist...
6019 if (I->getNumOperands() < 4)
6020 AddUsesToWorkList(*I);
6023 DEBUG(std::cerr << "IC: DCE: " << *I);
6025 I->eraseFromParent();
6026 removeFromWorkList(I);
6030 // Instruction isn't dead, see if we can constant propagate it...
6031 if (Constant *C = ConstantFoldInstruction(I)) {
6032 Value* Ptr = I->getOperand(0);
6033 if (isa<GetElementPtrInst>(I) &&
6034 cast<Constant>(Ptr)->isNullValue() &&
6035 !isa<ConstantPointerNull>(C) &&
6036 cast<PointerType>(Ptr->getType())->getElementType()->isSized()) {
6037 // If this is a constant expr gep that is effectively computing an
6038 // "offsetof", fold it into 'cast int X to T*' instead of 'gep 0, 0, 12'
6039 bool isFoldableGEP = true;
6040 for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
6041 if (!isa<ConstantInt>(I->getOperand(i)))
6042 isFoldableGEP = false;
6043 if (isFoldableGEP) {
6044 uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
6045 std::vector<Value*>(I->op_begin()+1, I->op_end()));
6046 C = ConstantUInt::get(Type::ULongTy, Offset);
6047 C = ConstantExpr::getCast(C, TD->getIntPtrType());
6048 C = ConstantExpr::getCast(C, I->getType());
6052 DEBUG(std::cerr << "IC: ConstFold to: " << *C << " from: " << *I);
6054 // Add operands to the worklist...
6055 AddUsesToWorkList(*I);
6056 ReplaceInstUsesWith(*I, C);
6059 I->getParent()->getInstList().erase(I);
6060 removeFromWorkList(I);
6064 // See if we can trivially sink this instruction to a successor basic block.
6065 if (I->hasOneUse()) {
6066 BasicBlock *BB = I->getParent();
6067 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
6068 if (UserParent != BB) {
6069 bool UserIsSuccessor = false;
6070 // See if the user is one of our successors.
6071 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
6072 if (*SI == UserParent) {
6073 UserIsSuccessor = true;
6077 // If the user is one of our immediate successors, and if that successor
6078 // only has us as a predecessors (we'd have to split the critical edge
6079 // otherwise), we can keep going.
6080 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
6081 next(pred_begin(UserParent)) == pred_end(UserParent))
6082 // Okay, the CFG is simple enough, try to sink this instruction.
6083 Changed |= TryToSinkInstruction(I, UserParent);
6087 // Now that we have an instruction, try combining it to simplify it...
6088 if (Instruction *Result = visit(*I)) {
6090 // Should we replace the old instruction with a new one?
6092 DEBUG(std::cerr << "IC: Old = " << *I
6093 << " New = " << *Result);
6095 // Everything uses the new instruction now.
6096 I->replaceAllUsesWith(Result);
6098 // Push the new instruction and any users onto the worklist.
6099 WorkList.push_back(Result);
6100 AddUsersToWorkList(*Result);
6102 // Move the name to the new instruction first...
6103 std::string OldName = I->getName(); I->setName("");
6104 Result->setName(OldName);
6106 // Insert the new instruction into the basic block...
6107 BasicBlock *InstParent = I->getParent();
6108 BasicBlock::iterator InsertPos = I;
6110 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
6111 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
6114 InstParent->getInstList().insert(InsertPos, Result);
6116 // Make sure that we reprocess all operands now that we reduced their
6118 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
6119 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
6120 WorkList.push_back(OpI);
6122 // Instructions can end up on the worklist more than once. Make sure
6123 // we do not process an instruction that has been deleted.
6124 removeFromWorkList(I);
6126 // Erase the old instruction.
6127 InstParent->getInstList().erase(I);
6129 DEBUG(std::cerr << "IC: MOD = " << *I);
6131 // If the instruction was modified, it's possible that it is now dead.
6132 // if so, remove it.
6133 if (isInstructionTriviallyDead(I)) {
6134 // Make sure we process all operands now that we are reducing their
6136 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
6137 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
6138 WorkList.push_back(OpI);
6140 // Instructions may end up in the worklist more than once. Erase all
6141 // occurrences of this instruction.
6142 removeFromWorkList(I);
6143 I->eraseFromParent();
6145 WorkList.push_back(Result);
6146 AddUsersToWorkList(*Result);
6156 FunctionPass *llvm::createInstructionCombiningPass() {
6157 return new InstCombiner();