1 //===- InstructionCombining.cpp - Combine multiple instructions -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // InstructionCombining - Combine instructions to form fewer, simple
11 // instructions. This pass does not modify the CFG This pass is where algebraic
12 // simplification happens.
14 // This pass combines things like:
20 // This is a simple worklist driven algorithm.
22 // This pass guarantees that the following canonicalizations are performed on
24 // 1. If a binary operator has a constant operand, it is moved to the RHS
25 // 2. Bitwise operators with constant operands are always grouped so that
26 // shifts are performed first, then or's, then and's, then xor's.
27 // 3. SetCC instructions are converted from <,>,<=,>= to ==,!= if possible
28 // 4. All SetCC instructions on boolean values are replaced with logical ops
29 // 5. add X, X is represented as (X*2) => (X << 1)
30 // 6. Multiplies with a power-of-two constant argument are transformed into
34 //===----------------------------------------------------------------------===//
36 #define DEBUG_TYPE "instcombine"
37 #include "llvm/Transforms/Scalar.h"
38 #include "llvm/IntrinsicInst.h"
39 #include "llvm/Pass.h"
40 #include "llvm/DerivedTypes.h"
41 #include "llvm/GlobalVariable.h"
42 #include "llvm/Target/TargetData.h"
43 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
44 #include "llvm/Transforms/Utils/Local.h"
45 #include "llvm/Support/CallSite.h"
46 #include "llvm/Support/Debug.h"
47 #include "llvm/Support/GetElementPtrTypeIterator.h"
48 #include "llvm/Support/InstVisitor.h"
49 #include "llvm/Support/MathExtras.h"
50 #include "llvm/Support/PatternMatch.h"
51 #include "llvm/ADT/DepthFirstIterator.h"
52 #include "llvm/ADT/Statistic.h"
53 #include "llvm/ADT/STLExtras.h"
56 using namespace llvm::PatternMatch;
59 Statistic<> NumCombined ("instcombine", "Number of insts combined");
60 Statistic<> NumConstProp("instcombine", "Number of constant folds");
61 Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
62 Statistic<> NumSunkInst ("instcombine", "Number of instructions sunk");
64 class InstCombiner : public FunctionPass,
65 public InstVisitor<InstCombiner, Instruction*> {
66 // Worklist of all of the instructions that need to be simplified.
67 std::vector<Instruction*> WorkList;
70 /// AddUsersToWorkList - When an instruction is simplified, add all users of
71 /// the instruction to the work lists because they might get more simplified
74 void AddUsersToWorkList(Instruction &I) {
75 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
77 WorkList.push_back(cast<Instruction>(*UI));
80 /// AddUsesToWorkList - When an instruction is simplified, add operands to
81 /// the work lists because they might get more simplified now.
83 void AddUsesToWorkList(Instruction &I) {
84 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
85 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
86 WorkList.push_back(Op);
89 // removeFromWorkList - remove all instances of I from the worklist.
90 void removeFromWorkList(Instruction *I);
92 virtual bool runOnFunction(Function &F);
94 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
95 AU.addRequired<TargetData>();
99 TargetData &getTargetData() const { return *TD; }
101 // Visitation implementation - Implement instruction combining for different
102 // instruction types. The semantics are as follows:
104 // null - No change was made
105 // I - Change was made, I is still valid, I may be dead though
106 // otherwise - Change was made, replace I with returned instruction
108 Instruction *visitAdd(BinaryOperator &I);
109 Instruction *visitSub(BinaryOperator &I);
110 Instruction *visitMul(BinaryOperator &I);
111 Instruction *visitDiv(BinaryOperator &I);
112 Instruction *visitRem(BinaryOperator &I);
113 Instruction *visitAnd(BinaryOperator &I);
114 Instruction *visitOr (BinaryOperator &I);
115 Instruction *visitXor(BinaryOperator &I);
116 Instruction *visitSetCondInst(SetCondInst &I);
117 Instruction *visitSetCondInstWithCastAndCast(SetCondInst &SCI);
119 Instruction *FoldGEPSetCC(User *GEPLHS, Value *RHS,
120 Instruction::BinaryOps Cond, Instruction &I);
121 Instruction *visitShiftInst(ShiftInst &I);
122 Instruction *visitCastInst(CastInst &CI);
123 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
125 Instruction *visitSelectInst(SelectInst &CI);
126 Instruction *visitCallInst(CallInst &CI);
127 Instruction *visitInvokeInst(InvokeInst &II);
128 Instruction *visitPHINode(PHINode &PN);
129 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
130 Instruction *visitAllocationInst(AllocationInst &AI);
131 Instruction *visitFreeInst(FreeInst &FI);
132 Instruction *visitLoadInst(LoadInst &LI);
133 Instruction *visitStoreInst(StoreInst &SI);
134 Instruction *visitBranchInst(BranchInst &BI);
135 Instruction *visitSwitchInst(SwitchInst &SI);
137 // visitInstruction - Specify what to return for unhandled instructions...
138 Instruction *visitInstruction(Instruction &I) { return 0; }
141 Instruction *visitCallSite(CallSite CS);
142 bool transformConstExprCastCall(CallSite CS);
145 // InsertNewInstBefore - insert an instruction New before instruction Old
146 // in the program. Add the new instruction to the worklist.
148 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
149 assert(New && New->getParent() == 0 &&
150 "New instruction already inserted into a basic block!");
151 BasicBlock *BB = Old.getParent();
152 BB->getInstList().insert(&Old, New); // Insert inst
153 WorkList.push_back(New); // Add to worklist
157 /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
158 /// This also adds the cast to the worklist. Finally, this returns the
160 Value *InsertCastBefore(Value *V, const Type *Ty, Instruction &Pos) {
161 if (V->getType() == Ty) return V;
163 Instruction *C = new CastInst(V, Ty, V->getName(), &Pos);
164 WorkList.push_back(C);
168 // ReplaceInstUsesWith - This method is to be used when an instruction is
169 // found to be dead, replacable with another preexisting expression. Here
170 // we add all uses of I to the worklist, replace all uses of I with the new
171 // value, then return I, so that the inst combiner will know that I was
174 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
175 AddUsersToWorkList(I); // Add all modified instrs to worklist
177 I.replaceAllUsesWith(V);
180 // If we are replacing the instruction with itself, this must be in a
181 // segment of unreachable code, so just clobber the instruction.
182 I.replaceAllUsesWith(UndefValue::get(I.getType()));
187 // EraseInstFromFunction - When dealing with an instruction that has side
188 // effects or produces a void value, we can't rely on DCE to delete the
189 // instruction. Instead, visit methods should return the value returned by
191 Instruction *EraseInstFromFunction(Instruction &I) {
192 assert(I.use_empty() && "Cannot erase instruction that is used!");
193 AddUsesToWorkList(I);
194 removeFromWorkList(&I);
196 return 0; // Don't do anything with FI
201 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
202 /// InsertBefore instruction. This is specialized a bit to avoid inserting
203 /// casts that are known to not do anything...
205 Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
206 Instruction *InsertBefore);
208 // SimplifyCommutative - This performs a few simplifications for commutative
210 bool SimplifyCommutative(BinaryOperator &I);
213 // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
214 // PHI node as operand #0, see if we can fold the instruction into the PHI
215 // (which is only possible if all operands to the PHI are constants).
216 Instruction *FoldOpIntoPhi(Instruction &I);
218 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
219 // operator and they all are only used by the PHI, PHI together their
220 // inputs, and do the operation once, to the result of the PHI.
221 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
223 Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
224 ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
226 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantIntegral *Mask,
227 bool isSub, Instruction &I);
228 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
229 bool Inside, Instruction &IB);
230 Instruction *PromoteCastOfAllocation(CastInst &CI, AllocationInst &AI);
233 RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
236 // getComplexity: Assign a complexity or rank value to LLVM Values...
237 // 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
238 static unsigned getComplexity(Value *V) {
239 if (isa<Instruction>(V)) {
240 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
244 if (isa<Argument>(V)) return 3;
245 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
248 // isOnlyUse - Return true if this instruction will be deleted if we stop using
250 static bool isOnlyUse(Value *V) {
251 return V->hasOneUse() || isa<Constant>(V);
254 // getPromotedType - Return the specified type promoted as it would be to pass
255 // though a va_arg area...
256 static const Type *getPromotedType(const Type *Ty) {
257 switch (Ty->getTypeID()) {
258 case Type::SByteTyID:
259 case Type::ShortTyID: return Type::IntTy;
260 case Type::UByteTyID:
261 case Type::UShortTyID: return Type::UIntTy;
262 case Type::FloatTyID: return Type::DoubleTy;
267 /// isCast - If the specified operand is a CastInst or a constant expr cast,
268 /// return the operand value, otherwise return null.
269 static Value *isCast(Value *V) {
270 if (CastInst *I = dyn_cast<CastInst>(V))
271 return I->getOperand(0);
272 else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
273 if (CE->getOpcode() == Instruction::Cast)
274 return CE->getOperand(0);
278 // SimplifyCommutative - This performs a few simplifications for commutative
281 // 1. Order operands such that they are listed from right (least complex) to
282 // left (most complex). This puts constants before unary operators before
285 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
286 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
288 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
289 bool Changed = false;
290 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
291 Changed = !I.swapOperands();
293 if (!I.isAssociative()) return Changed;
294 Instruction::BinaryOps Opcode = I.getOpcode();
295 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
296 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
297 if (isa<Constant>(I.getOperand(1))) {
298 Constant *Folded = ConstantExpr::get(I.getOpcode(),
299 cast<Constant>(I.getOperand(1)),
300 cast<Constant>(Op->getOperand(1)));
301 I.setOperand(0, Op->getOperand(0));
302 I.setOperand(1, Folded);
304 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
305 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
306 isOnlyUse(Op) && isOnlyUse(Op1)) {
307 Constant *C1 = cast<Constant>(Op->getOperand(1));
308 Constant *C2 = cast<Constant>(Op1->getOperand(1));
310 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
311 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
312 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
315 WorkList.push_back(New);
316 I.setOperand(0, New);
317 I.setOperand(1, Folded);
324 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
325 // if the LHS is a constant zero (which is the 'negate' form).
327 static inline Value *dyn_castNegVal(Value *V) {
328 if (BinaryOperator::isNeg(V))
329 return BinaryOperator::getNegArgument(V);
331 // Constants can be considered to be negated values if they can be folded.
332 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
333 return ConstantExpr::getNeg(C);
337 static inline Value *dyn_castNotVal(Value *V) {
338 if (BinaryOperator::isNot(V))
339 return BinaryOperator::getNotArgument(V);
341 // Constants can be considered to be not'ed values...
342 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
343 return ConstantExpr::getNot(C);
347 // dyn_castFoldableMul - If this value is a multiply that can be folded into
348 // other computations (because it has a constant operand), return the
349 // non-constant operand of the multiply, and set CST to point to the multiplier.
350 // Otherwise, return null.
352 static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
353 if (V->hasOneUse() && V->getType()->isInteger())
354 if (Instruction *I = dyn_cast<Instruction>(V)) {
355 if (I->getOpcode() == Instruction::Mul)
356 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
357 return I->getOperand(0);
358 if (I->getOpcode() == Instruction::Shl)
359 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
360 // The multiplier is really 1 << CST.
361 Constant *One = ConstantInt::get(V->getType(), 1);
362 CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
363 return I->getOperand(0);
369 /// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
370 /// expression, return it.
371 static User *dyn_castGetElementPtr(Value *V) {
372 if (isa<GetElementPtrInst>(V)) return cast<User>(V);
373 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
374 if (CE->getOpcode() == Instruction::GetElementPtr)
375 return cast<User>(V);
379 // AddOne, SubOne - Add or subtract a constant one from an integer constant...
380 static ConstantInt *AddOne(ConstantInt *C) {
381 return cast<ConstantInt>(ConstantExpr::getAdd(C,
382 ConstantInt::get(C->getType(), 1)));
384 static ConstantInt *SubOne(ConstantInt *C) {
385 return cast<ConstantInt>(ConstantExpr::getSub(C,
386 ConstantInt::get(C->getType(), 1)));
389 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
390 /// this predicate to simplify operations downstream. V and Mask are known to
391 /// be the same type.
392 static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask) {
393 // Note, we cannot consider 'undef' to be "IsZero" here. The problem is that
394 // we cannot optimize based on the assumption that it is zero without changing
395 // to to an explicit zero. If we don't change it to zero, other code could
396 // optimized based on the contradictory assumption that it is non-zero.
397 // Because instcombine aggressively folds operations with undef args anyway,
398 // this won't lose us code quality.
399 if (Mask->isNullValue())
401 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
402 return ConstantExpr::getAnd(CI, Mask)->isNullValue();
404 if (Instruction *I = dyn_cast<Instruction>(V)) {
405 switch (I->getOpcode()) {
406 case Instruction::And:
407 // (X & C1) & C2 == 0 iff C1 & C2 == 0.
408 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1))) {
409 ConstantIntegral *C1C2 =
410 cast<ConstantIntegral>(ConstantExpr::getAnd(CI, Mask));
411 if (MaskedValueIsZero(I->getOperand(0), C1C2))
414 // If either the LHS or the RHS are MaskedValueIsZero, the result is zero.
415 return MaskedValueIsZero(I->getOperand(1), Mask) ||
416 MaskedValueIsZero(I->getOperand(0), Mask);
417 case Instruction::Or:
418 case Instruction::Xor:
419 // If the LHS and the RHS are MaskedValueIsZero, the result is also zero.
420 return MaskedValueIsZero(I->getOperand(1), Mask) &&
421 MaskedValueIsZero(I->getOperand(0), Mask);
422 case Instruction::Select:
423 // If the T and F values are MaskedValueIsZero, the result is also zero.
424 return MaskedValueIsZero(I->getOperand(2), Mask) &&
425 MaskedValueIsZero(I->getOperand(1), Mask);
426 case Instruction::Cast: {
427 const Type *SrcTy = I->getOperand(0)->getType();
428 if (SrcTy == Type::BoolTy)
429 return (Mask->getRawValue() & 1) == 0;
431 if (SrcTy->isInteger()) {
432 // (cast <ty> X to int) & C2 == 0 iff <ty> could not have contained C2.
433 if (SrcTy->isUnsigned() && // Only handle zero ext.
434 ConstantExpr::getCast(Mask, SrcTy)->isNullValue())
437 // If this is a noop cast, recurse.
438 if ((SrcTy->isSigned() && SrcTy->getUnsignedVersion() == I->getType())||
439 SrcTy->getSignedVersion() == I->getType()) {
441 ConstantExpr::getCast(Mask, I->getOperand(0)->getType());
442 return MaskedValueIsZero(I->getOperand(0),
443 cast<ConstantIntegral>(NewMask));
448 case Instruction::Shl:
449 // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
450 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
451 return MaskedValueIsZero(I->getOperand(0),
452 cast<ConstantIntegral>(ConstantExpr::getUShr(Mask, SA)));
454 case Instruction::Shr:
455 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
456 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
457 if (I->getType()->isUnsigned()) {
458 Constant *C1 = ConstantIntegral::getAllOnesValue(I->getType());
459 C1 = ConstantExpr::getShr(C1, SA);
460 C1 = ConstantExpr::getAnd(C1, Mask);
461 if (C1->isNullValue())
471 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
472 // true when both operands are equal...
474 static bool isTrueWhenEqual(Instruction &I) {
475 return I.getOpcode() == Instruction::SetEQ ||
476 I.getOpcode() == Instruction::SetGE ||
477 I.getOpcode() == Instruction::SetLE;
480 /// AssociativeOpt - Perform an optimization on an associative operator. This
481 /// function is designed to check a chain of associative operators for a
482 /// potential to apply a certain optimization. Since the optimization may be
483 /// applicable if the expression was reassociated, this checks the chain, then
484 /// reassociates the expression as necessary to expose the optimization
485 /// opportunity. This makes use of a special Functor, which must define
486 /// 'shouldApply' and 'apply' methods.
488 template<typename Functor>
489 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
490 unsigned Opcode = Root.getOpcode();
491 Value *LHS = Root.getOperand(0);
493 // Quick check, see if the immediate LHS matches...
494 if (F.shouldApply(LHS))
495 return F.apply(Root);
497 // Otherwise, if the LHS is not of the same opcode as the root, return.
498 Instruction *LHSI = dyn_cast<Instruction>(LHS);
499 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
500 // Should we apply this transform to the RHS?
501 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
503 // If not to the RHS, check to see if we should apply to the LHS...
504 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
505 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
509 // If the functor wants to apply the optimization to the RHS of LHSI,
510 // reassociate the expression from ((? op A) op B) to (? op (A op B))
512 BasicBlock *BB = Root.getParent();
514 // Now all of the instructions are in the current basic block, go ahead
515 // and perform the reassociation.
516 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
518 // First move the selected RHS to the LHS of the root...
519 Root.setOperand(0, LHSI->getOperand(1));
521 // Make what used to be the LHS of the root be the user of the root...
522 Value *ExtraOperand = TmpLHSI->getOperand(1);
523 if (&Root == TmpLHSI) {
524 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
527 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
528 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
529 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
530 BasicBlock::iterator ARI = &Root; ++ARI;
531 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
534 // Now propagate the ExtraOperand down the chain of instructions until we
536 while (TmpLHSI != LHSI) {
537 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
538 // Move the instruction to immediately before the chain we are
539 // constructing to avoid breaking dominance properties.
540 NextLHSI->getParent()->getInstList().remove(NextLHSI);
541 BB->getInstList().insert(ARI, NextLHSI);
544 Value *NextOp = NextLHSI->getOperand(1);
545 NextLHSI->setOperand(1, ExtraOperand);
547 ExtraOperand = NextOp;
550 // Now that the instructions are reassociated, have the functor perform
551 // the transformation...
552 return F.apply(Root);
555 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
561 // AddRHS - Implements: X + X --> X << 1
564 AddRHS(Value *rhs) : RHS(rhs) {}
565 bool shouldApply(Value *LHS) const { return LHS == RHS; }
566 Instruction *apply(BinaryOperator &Add) const {
567 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
568 ConstantInt::get(Type::UByteTy, 1));
572 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
574 struct AddMaskingAnd {
576 AddMaskingAnd(Constant *c) : C2(c) {}
577 bool shouldApply(Value *LHS) const {
579 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
580 ConstantExpr::getAnd(C1, C2)->isNullValue();
582 Instruction *apply(BinaryOperator &Add) const {
583 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
587 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
589 if (isa<CastInst>(I)) {
590 if (Constant *SOC = dyn_cast<Constant>(SO))
591 return ConstantExpr::getCast(SOC, I.getType());
593 return IC->InsertNewInstBefore(new CastInst(SO, I.getType(),
594 SO->getName() + ".cast"), I);
597 // Figure out if the constant is the left or the right argument.
598 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
599 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
601 if (Constant *SOC = dyn_cast<Constant>(SO)) {
603 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
604 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
607 Value *Op0 = SO, *Op1 = ConstOperand;
611 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
612 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
613 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&I))
614 New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh");
616 assert(0 && "Unknown binary instruction type!");
619 return IC->InsertNewInstBefore(New, I);
622 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
623 // constant as the other operand, try to fold the binary operator into the
624 // select arguments. This also works for Cast instructions, which obviously do
625 // not have a second operand.
626 static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
628 // Don't modify shared select instructions
629 if (!SI->hasOneUse()) return 0;
630 Value *TV = SI->getOperand(1);
631 Value *FV = SI->getOperand(2);
633 if (isa<Constant>(TV) || isa<Constant>(FV)) {
634 // Bool selects with constant operands can be folded to logical ops.
635 if (SI->getType() == Type::BoolTy) return 0;
637 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
638 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
640 return new SelectInst(SI->getCondition(), SelectTrueVal,
647 /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
648 /// node as operand #0, see if we can fold the instruction into the PHI (which
649 /// is only possible if all operands to the PHI are constants).
650 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
651 PHINode *PN = cast<PHINode>(I.getOperand(0));
652 unsigned NumPHIValues = PN->getNumIncomingValues();
653 if (!PN->hasOneUse() || NumPHIValues == 0 ||
654 !isa<Constant>(PN->getIncomingValue(0))) return 0;
656 // Check to see if all of the operands of the PHI are constants. If not, we
657 // cannot do the transformation.
658 for (unsigned i = 1; i != NumPHIValues; ++i)
659 if (!isa<Constant>(PN->getIncomingValue(i)))
662 // Okay, we can do the transformation: create the new PHI node.
663 PHINode *NewPN = new PHINode(I.getType(), I.getName());
665 NewPN->reserveOperandSpace(PN->getNumOperands()/2);
666 InsertNewInstBefore(NewPN, *PN);
668 // Next, add all of the operands to the PHI.
669 if (I.getNumOperands() == 2) {
670 Constant *C = cast<Constant>(I.getOperand(1));
671 for (unsigned i = 0; i != NumPHIValues; ++i) {
672 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
673 NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
674 PN->getIncomingBlock(i));
677 assert(isa<CastInst>(I) && "Unary op should be a cast!");
678 const Type *RetTy = I.getType();
679 for (unsigned i = 0; i != NumPHIValues; ++i) {
680 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
681 NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
682 PN->getIncomingBlock(i));
685 return ReplaceInstUsesWith(I, NewPN);
688 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
689 bool Changed = SimplifyCommutative(I);
690 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
692 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
693 // X + undef -> undef
694 if (isa<UndefValue>(RHS))
695 return ReplaceInstUsesWith(I, RHS);
698 if (!I.getType()->isFloatingPoint()) { // NOTE: -0 + +0 = +0.
699 if (RHSC->isNullValue())
700 return ReplaceInstUsesWith(I, LHS);
701 } else if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
702 if (CFP->isExactlyValue(-0.0))
703 return ReplaceInstUsesWith(I, LHS);
706 // X + (signbit) --> X ^ signbit
707 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
708 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
709 uint64_t Val = CI->getRawValue() & (1ULL << NumBits)-1;
710 if (Val == (1ULL << (NumBits-1)))
711 return BinaryOperator::createXor(LHS, RHS);
714 if (isa<PHINode>(LHS))
715 if (Instruction *NV = FoldOpIntoPhi(I))
720 if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
721 unsigned TySizeBits = I.getType()->getPrimitiveSizeInBits();
722 int64_t RHSSExt = cast<ConstantInt>(RHSC)->getSExtValue();
723 uint64_t RHSZExt = cast<ConstantInt>(RHSC)->getZExtValue();
725 uint64_t C0080Val = 1ULL << 31;
726 int64_t CFF80Val = -C0080Val;
729 if (TySizeBits > Size) {
731 // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
732 // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
733 if (RHSSExt == CFF80Val) {
734 if (XorRHS->getZExtValue() == C0080Val)
736 } else if (RHSZExt == C0080Val) {
737 if (XorRHS->getSExtValue() == CFF80Val)
741 // This is a sign extend if the top bits are known zero.
742 Constant *Mask = ConstantInt::getAllOnesValue(XorLHS->getType());
743 Mask = ConstantExpr::getShl(Mask,
744 ConstantInt::get(Type::UByteTy, 64-TySizeBits-Size));
745 if (!MaskedValueIsZero(XorLHS, cast<ConstantInt>(Mask)))
746 Size = 0; // Not a sign ext, but can't be any others either.
756 const Type *MiddleType = 0;
759 case 32: MiddleType = Type::IntTy; break;
760 case 16: MiddleType = Type::ShortTy; break;
761 case 8: MiddleType = Type::SByteTy; break;
764 Instruction *NewTrunc = new CastInst(XorLHS, MiddleType, "sext");
765 InsertNewInstBefore(NewTrunc, I);
766 return new CastInst(NewTrunc, I.getType());
772 if (I.getType()->isInteger()) {
773 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
775 if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
776 if (RHSI->getOpcode() == Instruction::Sub)
777 if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
778 return ReplaceInstUsesWith(I, RHSI->getOperand(0));
780 if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
781 if (LHSI->getOpcode() == Instruction::Sub)
782 if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
783 return ReplaceInstUsesWith(I, LHSI->getOperand(0));
788 if (Value *V = dyn_castNegVal(LHS))
789 return BinaryOperator::createSub(RHS, V);
792 if (!isa<Constant>(RHS))
793 if (Value *V = dyn_castNegVal(RHS))
794 return BinaryOperator::createSub(LHS, V);
798 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
799 if (X == RHS) // X*C + X --> X * (C+1)
800 return BinaryOperator::createMul(RHS, AddOne(C2));
802 // X*C1 + X*C2 --> X * (C1+C2)
804 if (X == dyn_castFoldableMul(RHS, C1))
805 return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2));
808 // X + X*C --> X * (C+1)
809 if (dyn_castFoldableMul(RHS, C2) == LHS)
810 return BinaryOperator::createMul(LHS, AddOne(C2));
813 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
814 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
815 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
817 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
819 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
820 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
821 return BinaryOperator::createSub(C, X);
824 // (X & FF00) + xx00 -> (X+xx00) & FF00
825 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
826 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
828 // See if all bits from the first bit set in the Add RHS up are included
829 // in the mask. First, get the rightmost bit.
830 uint64_t AddRHSV = CRHS->getRawValue();
832 // Form a mask of all bits from the lowest bit added through the top.
833 uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
834 AddRHSHighBits &= ~0ULL >> (64-C2->getType()->getPrimitiveSizeInBits());
836 // See if the and mask includes all of these bits.
837 uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue();
839 if (AddRHSHighBits == AddRHSHighBitsAnd) {
840 // Okay, the xform is safe. Insert the new add pronto.
841 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
843 return BinaryOperator::createAnd(NewAdd, C2);
848 // Try to fold constant add into select arguments.
849 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
850 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
854 return Changed ? &I : 0;
857 // isSignBit - Return true if the value represented by the constant only has the
858 // highest order bit set.
859 static bool isSignBit(ConstantInt *CI) {
860 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
861 return (CI->getRawValue() & (~0ULL >> (64-NumBits))) == (1ULL << (NumBits-1));
864 /// RemoveNoopCast - Strip off nonconverting casts from the value.
866 static Value *RemoveNoopCast(Value *V) {
867 if (CastInst *CI = dyn_cast<CastInst>(V)) {
868 const Type *CTy = CI->getType();
869 const Type *OpTy = CI->getOperand(0)->getType();
870 if (CTy->isInteger() && OpTy->isInteger()) {
871 if (CTy->getPrimitiveSizeInBits() == OpTy->getPrimitiveSizeInBits())
872 return RemoveNoopCast(CI->getOperand(0));
873 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
874 return RemoveNoopCast(CI->getOperand(0));
879 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
880 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
882 if (Op0 == Op1) // sub X, X -> 0
883 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
885 // If this is a 'B = x-(-A)', change to B = x+A...
886 if (Value *V = dyn_castNegVal(Op1))
887 return BinaryOperator::createAdd(Op0, V);
889 if (isa<UndefValue>(Op0))
890 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
891 if (isa<UndefValue>(Op1))
892 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
894 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
895 // Replace (-1 - A) with (~A)...
896 if (C->isAllOnesValue())
897 return BinaryOperator::createNot(Op1);
899 // C - ~X == X + (1+C)
901 if (match(Op1, m_Not(m_Value(X))))
902 return BinaryOperator::createAdd(X,
903 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
904 // -((uint)X >> 31) -> ((int)X >> 31)
905 // -((int)X >> 31) -> ((uint)X >> 31)
906 if (C->isNullValue()) {
907 Value *NoopCastedRHS = RemoveNoopCast(Op1);
908 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
909 if (SI->getOpcode() == Instruction::Shr)
910 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
912 if (SI->getType()->isSigned())
913 NewTy = SI->getType()->getUnsignedVersion();
915 NewTy = SI->getType()->getSignedVersion();
916 // Check to see if we are shifting out everything but the sign bit.
917 if (CU->getValue() == SI->getType()->getPrimitiveSizeInBits()-1) {
918 // Ok, the transformation is safe. Insert a cast of the incoming
919 // value, then the new shift, then the new cast.
920 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
921 SI->getOperand(0)->getName());
922 Value *InV = InsertNewInstBefore(FirstCast, I);
923 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
925 if (NewShift->getType() == I.getType())
928 InV = InsertNewInstBefore(NewShift, I);
929 return new CastInst(NewShift, I.getType());
935 // Try to fold constant sub into select arguments.
936 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
937 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
940 if (isa<PHINode>(Op0))
941 if (Instruction *NV = FoldOpIntoPhi(I))
945 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
946 if (Op1I->getOpcode() == Instruction::Add &&
947 !Op0->getType()->isFloatingPoint()) {
948 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
949 return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
950 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
951 return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
952 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
953 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
954 // C1-(X+C2) --> (C1-C2)-X
955 return BinaryOperator::createSub(ConstantExpr::getSub(CI1, CI2),
956 Op1I->getOperand(0));
960 if (Op1I->hasOneUse()) {
961 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
962 // is not used by anyone else...
964 if (Op1I->getOpcode() == Instruction::Sub &&
965 !Op1I->getType()->isFloatingPoint()) {
966 // Swap the two operands of the subexpr...
967 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
968 Op1I->setOperand(0, IIOp1);
969 Op1I->setOperand(1, IIOp0);
971 // Create the new top level add instruction...
972 return BinaryOperator::createAdd(Op0, Op1);
975 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
977 if (Op1I->getOpcode() == Instruction::And &&
978 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
979 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
982 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
983 return BinaryOperator::createAnd(Op0, NewNot);
986 // -(X sdiv C) -> (X sdiv -C)
987 if (Op1I->getOpcode() == Instruction::Div)
988 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
989 if (CSI->isNullValue())
990 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
991 return BinaryOperator::createDiv(Op1I->getOperand(0),
992 ConstantExpr::getNeg(DivRHS));
994 // X - X*C --> X * (1-C)
996 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
998 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
999 return BinaryOperator::createMul(Op0, CP1);
1004 if (!Op0->getType()->isFloatingPoint())
1005 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
1006 if (Op0I->getOpcode() == Instruction::Add) {
1007 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
1008 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
1009 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
1010 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
1011 } else if (Op0I->getOpcode() == Instruction::Sub) {
1012 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
1013 return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName());
1017 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
1018 if (X == Op1) { // X*C - X --> X * (C-1)
1019 Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
1020 return BinaryOperator::createMul(Op1, CP1);
1023 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
1024 if (X == dyn_castFoldableMul(Op1, C2))
1025 return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
1030 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
1031 /// really just returns true if the most significant (sign) bit is set.
1032 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
1033 if (RHS->getType()->isSigned()) {
1034 // True if source is LHS < 0 or LHS <= -1
1035 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
1036 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
1038 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
1039 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
1040 // the size of the integer type.
1041 if (Opcode == Instruction::SetGE)
1042 return RHSC->getValue() ==
1043 1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1);
1044 if (Opcode == Instruction::SetGT)
1045 return RHSC->getValue() ==
1046 (1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1))-1;
1051 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
1052 bool Changed = SimplifyCommutative(I);
1053 Value *Op0 = I.getOperand(0);
1055 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
1056 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1058 // Simplify mul instructions with a constant RHS...
1059 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
1060 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
1062 // ((X << C1)*C2) == (X * (C2 << C1))
1063 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
1064 if (SI->getOpcode() == Instruction::Shl)
1065 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
1066 return BinaryOperator::createMul(SI->getOperand(0),
1067 ConstantExpr::getShl(CI, ShOp));
1069 if (CI->isNullValue())
1070 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
1071 if (CI->equalsInt(1)) // X * 1 == X
1072 return ReplaceInstUsesWith(I, Op0);
1073 if (CI->isAllOnesValue()) // X * -1 == 0 - X
1074 return BinaryOperator::createNeg(Op0, I.getName());
1076 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
1077 if (isPowerOf2_64(Val)) { // Replace X*(2^C) with X << C
1078 uint64_t C = Log2_64(Val);
1079 return new ShiftInst(Instruction::Shl, Op0,
1080 ConstantUInt::get(Type::UByteTy, C));
1082 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
1083 if (Op1F->isNullValue())
1084 return ReplaceInstUsesWith(I, Op1);
1086 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
1087 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
1088 if (Op1F->getValue() == 1.0)
1089 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
1092 // Try to fold constant mul into select arguments.
1093 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1094 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1097 if (isa<PHINode>(Op0))
1098 if (Instruction *NV = FoldOpIntoPhi(I))
1102 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
1103 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
1104 return BinaryOperator::createMul(Op0v, Op1v);
1106 // If one of the operands of the multiply is a cast from a boolean value, then
1107 // we know the bool is either zero or one, so this is a 'masking' multiply.
1108 // See if we can simplify things based on how the boolean was originally
1110 CastInst *BoolCast = 0;
1111 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
1112 if (CI->getOperand(0)->getType() == Type::BoolTy)
1115 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
1116 if (CI->getOperand(0)->getType() == Type::BoolTy)
1119 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
1120 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
1121 const Type *SCOpTy = SCIOp0->getType();
1123 // If the setcc is true iff the sign bit of X is set, then convert this
1124 // multiply into a shift/and combination.
1125 if (isa<ConstantInt>(SCIOp1) &&
1126 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
1127 // Shift the X value right to turn it into "all signbits".
1128 Constant *Amt = ConstantUInt::get(Type::UByteTy,
1129 SCOpTy->getPrimitiveSizeInBits()-1);
1130 if (SCIOp0->getType()->isUnsigned()) {
1131 const Type *NewTy = SCIOp0->getType()->getSignedVersion();
1132 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
1133 SCIOp0->getName()), I);
1137 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
1138 BoolCast->getOperand(0)->getName()+
1141 // If the multiply type is not the same as the source type, sign extend
1142 // or truncate to the multiply type.
1143 if (I.getType() != V->getType())
1144 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
1146 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
1147 return BinaryOperator::createAnd(V, OtherOp);
1152 return Changed ? &I : 0;
1155 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
1156 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1158 if (isa<UndefValue>(Op0)) // undef / X -> 0
1159 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1160 if (isa<UndefValue>(Op1))
1161 return ReplaceInstUsesWith(I, Op1); // X / undef -> undef
1163 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1165 if (RHS->equalsInt(1))
1166 return ReplaceInstUsesWith(I, Op0);
1169 if (RHS->isAllOnesValue())
1170 return BinaryOperator::createNeg(Op0);
1172 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
1173 if (LHS->getOpcode() == Instruction::Div)
1174 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
1175 // (X / C1) / C2 -> X / (C1*C2)
1176 return BinaryOperator::createDiv(LHS->getOperand(0),
1177 ConstantExpr::getMul(RHS, LHSRHS));
1180 // Check to see if this is an unsigned division with an exact power of 2,
1181 // if so, convert to a right shift.
1182 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1183 if (uint64_t Val = C->getValue()) // Don't break X / 0
1184 if (isPowerOf2_64(Val)) {
1185 uint64_t C = Log2_64(Val);
1186 return new ShiftInst(Instruction::Shr, Op0,
1187 ConstantUInt::get(Type::UByteTy, C));
1191 if (RHS->getType()->isSigned())
1192 if (Value *LHSNeg = dyn_castNegVal(Op0))
1193 return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS));
1195 if (!RHS->isNullValue()) {
1196 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1197 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1199 if (isa<PHINode>(Op0))
1200 if (Instruction *NV = FoldOpIntoPhi(I))
1205 // If this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1206 // transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'.
1207 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1208 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1209 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1210 if (STO->getValue() == 0) { // Couldn't be this argument.
1211 I.setOperand(1, SFO);
1213 } else if (SFO->getValue() == 0) {
1214 I.setOperand(1, STO);
1218 uint64_t TVA = STO->getValue(), FVA = SFO->getValue();
1219 if (isPowerOf2_64(TVA) && isPowerOf2_64(FVA)) {
1220 unsigned TSA = Log2_64(TVA), FSA = Log2_64(FVA);
1221 Constant *TC = ConstantUInt::get(Type::UByteTy, TSA);
1222 Instruction *TSI = new ShiftInst(Instruction::Shr, Op0,
1223 TC, SI->getName()+".t");
1224 TSI = InsertNewInstBefore(TSI, I);
1226 Constant *FC = ConstantUInt::get(Type::UByteTy, FSA);
1227 Instruction *FSI = new ShiftInst(Instruction::Shr, Op0,
1228 FC, SI->getName()+".f");
1229 FSI = InsertNewInstBefore(FSI, I);
1230 return new SelectInst(SI->getOperand(0), TSI, FSI);
1234 // 0 / X == 0, we don't need to preserve faults!
1235 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1236 if (LHS->equalsInt(0))
1237 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1243 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
1244 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1245 if (I.getType()->isSigned())
1246 if (Value *RHSNeg = dyn_castNegVal(Op1))
1247 if (!isa<ConstantSInt>(RHSNeg) ||
1248 cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
1250 AddUsesToWorkList(I);
1251 I.setOperand(1, RHSNeg);
1255 if (isa<UndefValue>(Op0)) // undef % X -> 0
1256 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1257 if (isa<UndefValue>(Op1))
1258 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
1260 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1261 if (RHS->equalsInt(1)) // X % 1 == 0
1262 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1264 // Check to see if this is an unsigned remainder with an exact power of 2,
1265 // if so, convert to a bitwise and.
1266 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1267 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
1268 if (!(Val & (Val-1))) // Power of 2
1269 return BinaryOperator::createAnd(Op0,
1270 ConstantUInt::get(I.getType(), Val-1));
1272 if (!RHS->isNullValue()) {
1273 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1274 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1276 if (isa<PHINode>(Op0))
1277 if (Instruction *NV = FoldOpIntoPhi(I))
1282 // If this is 'urem X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1283 // transform this into: '(Cond ? (urem X, C1) : (urem X, C2))'.
1284 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1285 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1286 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1287 if (STO->getValue() == 0) { // Couldn't be this argument.
1288 I.setOperand(1, SFO);
1290 } else if (SFO->getValue() == 0) {
1291 I.setOperand(1, STO);
1295 if (!(STO->getValue() & (STO->getValue()-1)) &&
1296 !(SFO->getValue() & (SFO->getValue()-1))) {
1297 Value *TrueAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1298 SubOne(STO), SI->getName()+".t"), I);
1299 Value *FalseAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1300 SubOne(SFO), SI->getName()+".f"), I);
1301 return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
1305 // 0 % X == 0, we don't need to preserve faults!
1306 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1307 if (LHS->equalsInt(0))
1308 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1313 // isMaxValueMinusOne - return true if this is Max-1
1314 static bool isMaxValueMinusOne(const ConstantInt *C) {
1315 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
1316 // Calculate -1 casted to the right type...
1317 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1318 uint64_t Val = ~0ULL; // All ones
1319 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1320 return CU->getValue() == Val-1;
1323 const ConstantSInt *CS = cast<ConstantSInt>(C);
1325 // Calculate 0111111111..11111
1326 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1327 int64_t Val = INT64_MAX; // All ones
1328 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1329 return CS->getValue() == Val-1;
1332 // isMinValuePlusOne - return true if this is Min+1
1333 static bool isMinValuePlusOne(const ConstantInt *C) {
1334 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1335 return CU->getValue() == 1;
1337 const ConstantSInt *CS = cast<ConstantSInt>(C);
1339 // Calculate 1111111111000000000000
1340 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1341 int64_t Val = -1; // All ones
1342 Val <<= TypeBits-1; // Shift over to the right spot
1343 return CS->getValue() == Val+1;
1346 // isOneBitSet - Return true if there is exactly one bit set in the specified
1348 static bool isOneBitSet(const ConstantInt *CI) {
1349 uint64_t V = CI->getRawValue();
1350 return V && (V & (V-1)) == 0;
1353 #if 0 // Currently unused
1354 // isLowOnes - Return true if the constant is of the form 0+1+.
1355 static bool isLowOnes(const ConstantInt *CI) {
1356 uint64_t V = CI->getRawValue();
1358 // There won't be bits set in parts that the type doesn't contain.
1359 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1361 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1362 return U && V && (U & V) == 0;
1366 // isHighOnes - Return true if the constant is of the form 1+0+.
1367 // This is the same as lowones(~X).
1368 static bool isHighOnes(const ConstantInt *CI) {
1369 uint64_t V = ~CI->getRawValue();
1370 if (~V == 0) return false; // 0's does not match "1+"
1372 // There won't be bits set in parts that the type doesn't contain.
1373 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1375 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1376 return U && V && (U & V) == 0;
1380 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
1381 /// are carefully arranged to allow folding of expressions such as:
1383 /// (A < B) | (A > B) --> (A != B)
1385 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
1386 /// represents that the comparison is true if A == B, and bit value '1' is true
1389 static unsigned getSetCondCode(const SetCondInst *SCI) {
1390 switch (SCI->getOpcode()) {
1392 case Instruction::SetGT: return 1;
1393 case Instruction::SetEQ: return 2;
1394 case Instruction::SetGE: return 3;
1395 case Instruction::SetLT: return 4;
1396 case Instruction::SetNE: return 5;
1397 case Instruction::SetLE: return 6;
1400 assert(0 && "Invalid SetCC opcode!");
1405 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
1406 /// opcode and two operands into either a constant true or false, or a brand new
1407 /// SetCC instruction.
1408 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
1410 case 0: return ConstantBool::False;
1411 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
1412 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
1413 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
1414 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
1415 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
1416 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
1417 case 7: return ConstantBool::True;
1418 default: assert(0 && "Illegal SetCCCode!"); return 0;
1422 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1423 struct FoldSetCCLogical {
1426 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
1427 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
1428 bool shouldApply(Value *V) const {
1429 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
1430 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
1431 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
1434 Instruction *apply(BinaryOperator &Log) const {
1435 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
1436 if (SCI->getOperand(0) != LHS) {
1437 assert(SCI->getOperand(1) == LHS);
1438 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
1441 unsigned LHSCode = getSetCondCode(SCI);
1442 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
1444 switch (Log.getOpcode()) {
1445 case Instruction::And: Code = LHSCode & RHSCode; break;
1446 case Instruction::Or: Code = LHSCode | RHSCode; break;
1447 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
1448 default: assert(0 && "Illegal logical opcode!"); return 0;
1451 Value *RV = getSetCCValue(Code, LHS, RHS);
1452 if (Instruction *I = dyn_cast<Instruction>(RV))
1454 // Otherwise, it's a constant boolean value...
1455 return IC.ReplaceInstUsesWith(Log, RV);
1459 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
1460 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
1461 // guaranteed to be either a shift instruction or a binary operator.
1462 Instruction *InstCombiner::OptAndOp(Instruction *Op,
1463 ConstantIntegral *OpRHS,
1464 ConstantIntegral *AndRHS,
1465 BinaryOperator &TheAnd) {
1466 Value *X = Op->getOperand(0);
1467 Constant *Together = 0;
1468 if (!isa<ShiftInst>(Op))
1469 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
1471 switch (Op->getOpcode()) {
1472 case Instruction::Xor:
1473 if (Op->hasOneUse()) {
1474 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
1475 std::string OpName = Op->getName(); Op->setName("");
1476 Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
1477 InsertNewInstBefore(And, TheAnd);
1478 return BinaryOperator::createXor(And, Together);
1481 case Instruction::Or:
1482 if (Together == AndRHS) // (X | C) & C --> C
1483 return ReplaceInstUsesWith(TheAnd, AndRHS);
1485 if (Op->hasOneUse() && Together != OpRHS) {
1486 // (X | C1) & C2 --> (X | (C1&C2)) & C2
1487 std::string Op0Name = Op->getName(); Op->setName("");
1488 Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
1489 InsertNewInstBefore(Or, TheAnd);
1490 return BinaryOperator::createAnd(Or, AndRHS);
1493 case Instruction::Add:
1494 if (Op->hasOneUse()) {
1495 // Adding a one to a single bit bit-field should be turned into an XOR
1496 // of the bit. First thing to check is to see if this AND is with a
1497 // single bit constant.
1498 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
1500 // Clear bits that are not part of the constant.
1501 AndRHSV &= ~0ULL >> (64-AndRHS->getType()->getPrimitiveSizeInBits());
1503 // If there is only one bit set...
1504 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
1505 // Ok, at this point, we know that we are masking the result of the
1506 // ADD down to exactly one bit. If the constant we are adding has
1507 // no bits set below this bit, then we can eliminate the ADD.
1508 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
1510 // Check to see if any bits below the one bit set in AndRHSV are set.
1511 if ((AddRHS & (AndRHSV-1)) == 0) {
1512 // If not, the only thing that can effect the output of the AND is
1513 // the bit specified by AndRHSV. If that bit is set, the effect of
1514 // the XOR is to toggle the bit. If it is clear, then the ADD has
1516 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
1517 TheAnd.setOperand(0, X);
1520 std::string Name = Op->getName(); Op->setName("");
1521 // Pull the XOR out of the AND.
1522 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
1523 InsertNewInstBefore(NewAnd, TheAnd);
1524 return BinaryOperator::createXor(NewAnd, AndRHS);
1531 case Instruction::Shl: {
1532 // We know that the AND will not produce any of the bits shifted in, so if
1533 // the anded constant includes them, clear them now!
1535 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1536 Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
1537 Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
1539 if (CI == ShlMask) { // Masking out bits that the shift already masks
1540 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
1541 } else if (CI != AndRHS) { // Reducing bits set in and.
1542 TheAnd.setOperand(1, CI);
1547 case Instruction::Shr:
1548 // We know that the AND will not produce any of the bits shifted in, so if
1549 // the anded constant includes them, clear them now! This only applies to
1550 // unsigned shifts, because a signed shr may bring in set bits!
1552 if (AndRHS->getType()->isUnsigned()) {
1553 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1554 Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS);
1555 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1557 if (CI == ShrMask) { // Masking out bits that the shift already masks.
1558 return ReplaceInstUsesWith(TheAnd, Op);
1559 } else if (CI != AndRHS) {
1560 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
1563 } else { // Signed shr.
1564 // See if this is shifting in some sign extension, then masking it out
1566 if (Op->hasOneUse()) {
1567 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1568 Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS);
1569 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1570 if (CI == AndRHS) { // Masking out bits shifted in.
1571 // Make the argument unsigned.
1572 Value *ShVal = Op->getOperand(0);
1573 ShVal = InsertCastBefore(ShVal,
1574 ShVal->getType()->getUnsignedVersion(),
1576 ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal,
1577 OpRHS, Op->getName()),
1579 Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType());
1580 ShVal = InsertNewInstBefore(BinaryOperator::createAnd(ShVal, AndRHS2,
1583 return new CastInst(ShVal, Op->getType());
1593 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
1594 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
1595 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. IB is the location to
1596 /// insert new instructions.
1597 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
1598 bool Inside, Instruction &IB) {
1599 assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
1600 "Lo is not <= Hi in range emission code!");
1602 if (Lo == Hi) // Trivially false.
1603 return new SetCondInst(Instruction::SetNE, V, V);
1604 if (cast<ConstantIntegral>(Lo)->isMinValue())
1605 return new SetCondInst(Instruction::SetLT, V, Hi);
1607 Constant *AddCST = ConstantExpr::getNeg(Lo);
1608 Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
1609 InsertNewInstBefore(Add, IB);
1610 // Convert to unsigned for the comparison.
1611 const Type *UnsType = Add->getType()->getUnsignedVersion();
1612 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1613 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1614 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1615 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1618 if (Lo == Hi) // Trivially true.
1619 return new SetCondInst(Instruction::SetEQ, V, V);
1621 Hi = SubOne(cast<ConstantInt>(Hi));
1622 if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
1623 return new SetCondInst(Instruction::SetGT, V, Hi);
1625 // Emit X-Lo > Hi-Lo-1
1626 Constant *AddCST = ConstantExpr::getNeg(Lo);
1627 Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
1628 InsertNewInstBefore(Add, IB);
1629 // Convert to unsigned for the comparison.
1630 const Type *UnsType = Add->getType()->getUnsignedVersion();
1631 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1632 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1633 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1634 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1637 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
1638 // any number of 0s on either side. The 1s are allowed to wrap from LSB to
1639 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
1640 // not, since all 1s are not contiguous.
1641 static bool isRunOfOnes(ConstantIntegral *Val, unsigned &MB, unsigned &ME) {
1642 uint64_t V = Val->getRawValue();
1643 if (!isShiftedMask_64(V)) return false;
1645 // look for the first zero bit after the run of ones
1646 MB = 64-CountLeadingZeros_64((V - 1) ^ V);
1647 // look for the first non-zero bit
1648 ME = 64-CountLeadingZeros_64(V);
1654 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
1655 /// where isSub determines whether the operator is a sub. If we can fold one of
1656 /// the following xforms:
1658 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
1659 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
1660 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
1662 /// return (A +/- B).
1664 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
1665 ConstantIntegral *Mask, bool isSub,
1667 Instruction *LHSI = dyn_cast<Instruction>(LHS);
1668 if (!LHSI || LHSI->getNumOperands() != 2 ||
1669 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
1671 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
1673 switch (LHSI->getOpcode()) {
1675 case Instruction::And:
1676 if (ConstantExpr::getAnd(N, Mask) == Mask) {
1677 // If the AndRHS is a power of two minus one (0+1+), this is simple.
1678 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0)
1681 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
1682 // part, we don't need any explicit masks to take them out of A. If that
1683 // is all N is, ignore it.
1685 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
1686 Constant *Mask = ConstantInt::getAllOnesValue(RHS->getType());
1687 Mask = ConstantExpr::getUShr(Mask,
1688 ConstantInt::get(Type::UByteTy,
1690 if (MaskedValueIsZero(RHS, cast<ConstantIntegral>(Mask)))
1695 case Instruction::Or:
1696 case Instruction::Xor:
1697 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
1698 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0 &&
1699 ConstantExpr::getAnd(N, Mask)->isNullValue())
1706 New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold");
1708 New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold");
1709 return InsertNewInstBefore(New, I);
1713 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1714 bool Changed = SimplifyCommutative(I);
1715 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1717 if (isa<UndefValue>(Op1)) // X & undef -> 0
1718 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1722 return ReplaceInstUsesWith(I, Op1);
1724 if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) {
1726 if (AndRHS->isAllOnesValue())
1727 return ReplaceInstUsesWith(I, Op0);
1729 if (MaskedValueIsZero(Op0, AndRHS)) // LHS & RHS == 0
1730 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1732 // If the mask is not masking out any bits, there is no reason to do the
1733 // and in the first place.
1734 ConstantIntegral *NotAndRHS =
1735 cast<ConstantIntegral>(ConstantExpr::getNot(AndRHS));
1736 if (MaskedValueIsZero(Op0, NotAndRHS))
1737 return ReplaceInstUsesWith(I, Op0);
1739 // Optimize a variety of ((val OP C1) & C2) combinations...
1740 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
1741 Instruction *Op0I = cast<Instruction>(Op0);
1742 Value *Op0LHS = Op0I->getOperand(0);
1743 Value *Op0RHS = Op0I->getOperand(1);
1744 switch (Op0I->getOpcode()) {
1745 case Instruction::Xor:
1746 case Instruction::Or:
1747 // (X ^ V) & C2 --> (X & C2) iff (V & C2) == 0
1748 // (X | V) & C2 --> (X & C2) iff (V & C2) == 0
1749 if (MaskedValueIsZero(Op0LHS, AndRHS))
1750 return BinaryOperator::createAnd(Op0RHS, AndRHS);
1751 if (MaskedValueIsZero(Op0RHS, AndRHS))
1752 return BinaryOperator::createAnd(Op0LHS, AndRHS);
1754 // If the mask is only needed on one incoming arm, push it up.
1755 if (Op0I->hasOneUse()) {
1756 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
1757 // Not masking anything out for the LHS, move to RHS.
1758 Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
1759 Op0RHS->getName()+".masked");
1760 InsertNewInstBefore(NewRHS, I);
1761 return BinaryOperator::create(
1762 cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
1764 if (!isa<Constant>(NotAndRHS) &&
1765 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
1766 // Not masking anything out for the RHS, move to LHS.
1767 Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
1768 Op0LHS->getName()+".masked");
1769 InsertNewInstBefore(NewLHS, I);
1770 return BinaryOperator::create(
1771 cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
1776 case Instruction::And:
1777 // (X & V) & C2 --> 0 iff (V & C2) == 0
1778 if (MaskedValueIsZero(Op0LHS, AndRHS) ||
1779 MaskedValueIsZero(Op0RHS, AndRHS))
1780 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1782 case Instruction::Add:
1783 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
1784 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1785 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1786 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
1787 return BinaryOperator::createAnd(V, AndRHS);
1788 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
1789 return BinaryOperator::createAnd(V, AndRHS); // Add commutes
1792 case Instruction::Sub:
1793 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
1794 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1795 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1796 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
1797 return BinaryOperator::createAnd(V, AndRHS);
1801 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1802 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
1804 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
1805 const Type *SrcTy = CI->getOperand(0)->getType();
1807 // If this is an integer truncation or change from signed-to-unsigned, and
1808 // if the source is an and/or with immediate, transform it. This
1809 // frequently occurs for bitfield accesses.
1810 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
1811 if (SrcTy->getPrimitiveSizeInBits() >=
1812 I.getType()->getPrimitiveSizeInBits() &&
1813 CastOp->getNumOperands() == 2)
1814 if (ConstantInt *AndCI =dyn_cast<ConstantInt>(CastOp->getOperand(1)))
1815 if (CastOp->getOpcode() == Instruction::And) {
1816 // Change: and (cast (and X, C1) to T), C2
1817 // into : and (cast X to T), trunc(C1)&C2
1818 // This will folds the two ands together, which may allow other
1820 Instruction *NewCast =
1821 new CastInst(CastOp->getOperand(0), I.getType(),
1822 CastOp->getName()+".shrunk");
1823 NewCast = InsertNewInstBefore(NewCast, I);
1825 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1826 C3 = ConstantExpr::getAnd(C3, AndRHS); // trunc(C1)&C2
1827 return BinaryOperator::createAnd(NewCast, C3);
1828 } else if (CastOp->getOpcode() == Instruction::Or) {
1829 // Change: and (cast (or X, C1) to T), C2
1830 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
1831 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1832 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
1833 return ReplaceInstUsesWith(I, AndRHS);
1838 // If this is an integer sign or zero extension instruction.
1839 if (SrcTy->isIntegral() &&
1840 SrcTy->getPrimitiveSizeInBits() <
1841 CI->getType()->getPrimitiveSizeInBits()) {
1843 if (SrcTy->isUnsigned()) {
1844 // See if this and is clearing out bits that are known to be zero
1845 // anyway (due to the zero extension).
1846 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1847 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1848 Constant *Result = ConstantExpr::getAnd(Mask, AndRHS);
1849 if (Result == Mask) // The "and" isn't doing anything, remove it.
1850 return ReplaceInstUsesWith(I, CI);
1851 if (Result != AndRHS) { // Reduce the and RHS constant.
1852 I.setOperand(1, Result);
1857 if (CI->hasOneUse() && SrcTy->isInteger()) {
1858 // We can only do this if all of the sign bits brought in are masked
1859 // out. Compute this by first getting 0000011111, then inverting
1861 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1862 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1863 Mask = ConstantExpr::getNot(Mask); // 1's in the new bits.
1864 if (ConstantExpr::getAnd(Mask, AndRHS)->isNullValue()) {
1865 // If the and is clearing all of the sign bits, change this to a
1866 // zero extension cast. To do this, cast the cast input to
1867 // unsigned, then to the requested size.
1868 Value *CastOp = CI->getOperand(0);
1870 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
1871 CI->getName()+".uns");
1872 NC = InsertNewInstBefore(NC, I);
1873 // Finally, insert a replacement for CI.
1874 NC = new CastInst(NC, CI->getType(), CI->getName());
1876 NC = InsertNewInstBefore(NC, I);
1877 WorkList.push_back(CI); // Delete CI later.
1878 I.setOperand(0, NC);
1879 return &I; // The AND operand was modified.
1886 // Try to fold constant and into select arguments.
1887 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1888 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1890 if (isa<PHINode>(Op0))
1891 if (Instruction *NV = FoldOpIntoPhi(I))
1895 Value *Op0NotVal = dyn_castNotVal(Op0);
1896 Value *Op1NotVal = dyn_castNotVal(Op1);
1898 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1899 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1901 // (~A & ~B) == (~(A | B)) - De Morgan's Law
1902 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1903 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
1904 I.getName()+".demorgan");
1905 InsertNewInstBefore(Or, I);
1906 return BinaryOperator::createNot(Or);
1909 if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
1910 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1911 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1914 Value *LHSVal, *RHSVal;
1915 ConstantInt *LHSCst, *RHSCst;
1916 Instruction::BinaryOps LHSCC, RHSCC;
1917 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1918 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1919 if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
1920 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1921 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1922 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1923 // Ensure that the larger constant is on the RHS.
1924 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1925 SetCondInst *LHS = cast<SetCondInst>(Op0);
1926 if (cast<ConstantBool>(Cmp)->getValue()) {
1927 std::swap(LHS, RHS);
1928 std::swap(LHSCst, RHSCst);
1929 std::swap(LHSCC, RHSCC);
1932 // At this point, we know we have have two setcc instructions
1933 // comparing a value against two constants and and'ing the result
1934 // together. Because of the above check, we know that we only have
1935 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1936 // FoldSetCCLogical check above), that the two constants are not
1938 assert(LHSCst != RHSCst && "Compares not folded above?");
1941 default: assert(0 && "Unknown integer condition code!");
1942 case Instruction::SetEQ:
1944 default: assert(0 && "Unknown integer condition code!");
1945 case Instruction::SetEQ: // (X == 13 & X == 15) -> false
1946 case Instruction::SetGT: // (X == 13 & X > 15) -> false
1947 return ReplaceInstUsesWith(I, ConstantBool::False);
1948 case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
1949 case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
1950 return ReplaceInstUsesWith(I, LHS);
1952 case Instruction::SetNE:
1954 default: assert(0 && "Unknown integer condition code!");
1955 case Instruction::SetLT:
1956 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
1957 return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
1958 break; // (X != 13 & X < 15) -> no change
1959 case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
1960 case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
1961 return ReplaceInstUsesWith(I, RHS);
1962 case Instruction::SetNE:
1963 if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
1964 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1965 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
1966 LHSVal->getName()+".off");
1967 InsertNewInstBefore(Add, I);
1968 const Type *UnsType = Add->getType()->getUnsignedVersion();
1969 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
1970 AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
1971 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1972 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1974 break; // (X != 13 & X != 15) -> no change
1977 case Instruction::SetLT:
1979 default: assert(0 && "Unknown integer condition code!");
1980 case Instruction::SetEQ: // (X < 13 & X == 15) -> false
1981 case Instruction::SetGT: // (X < 13 & X > 15) -> false
1982 return ReplaceInstUsesWith(I, ConstantBool::False);
1983 case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
1984 case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
1985 return ReplaceInstUsesWith(I, LHS);
1987 case Instruction::SetGT:
1989 default: assert(0 && "Unknown integer condition code!");
1990 case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
1991 return ReplaceInstUsesWith(I, LHS);
1992 case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
1993 return ReplaceInstUsesWith(I, RHS);
1994 case Instruction::SetNE:
1995 if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
1996 return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
1997 break; // (X > 13 & X != 15) -> no change
1998 case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
1999 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
2005 return Changed ? &I : 0;
2008 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
2009 bool Changed = SimplifyCommutative(I);
2010 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2012 if (isa<UndefValue>(Op1))
2013 return ReplaceInstUsesWith(I, // X | undef -> -1
2014 ConstantIntegral::getAllOnesValue(I.getType()));
2016 // or X, X = X or X, 0 == X
2017 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
2018 return ReplaceInstUsesWith(I, Op0);
2021 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2022 // If X is known to only contain bits that already exist in RHS, just
2023 // replace this instruction with RHS directly.
2024 if (MaskedValueIsZero(Op0,
2025 cast<ConstantIntegral>(ConstantExpr::getNot(RHS))))
2026 return ReplaceInstUsesWith(I, RHS);
2028 ConstantInt *C1; Value *X;
2029 // (X & C1) | C2 --> (X | C2) & (C1|C2)
2030 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
2031 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0->getName());
2033 InsertNewInstBefore(Or, I);
2034 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
2037 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
2038 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
2039 std::string Op0Name = Op0->getName(); Op0->setName("");
2040 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
2041 InsertNewInstBefore(Or, I);
2042 return BinaryOperator::createXor(Or,
2043 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
2046 // Try to fold constant and into select arguments.
2047 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2048 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2050 if (isa<PHINode>(Op0))
2051 if (Instruction *NV = FoldOpIntoPhi(I))
2055 Value *A, *B; ConstantInt *C1, *C2;
2057 if (match(Op0, m_And(m_Value(A), m_Value(B))))
2058 if (A == Op1 || B == Op1) // (A & ?) | A --> A
2059 return ReplaceInstUsesWith(I, Op1);
2060 if (match(Op1, m_And(m_Value(A), m_Value(B))))
2061 if (A == Op0 || B == Op0) // A | (A & ?) --> A
2062 return ReplaceInstUsesWith(I, Op0);
2064 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
2065 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2066 MaskedValueIsZero(Op1, C1)) {
2067 Instruction *NOr = BinaryOperator::createOr(A, Op1, Op0->getName());
2069 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2072 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
2073 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2074 MaskedValueIsZero(Op0, C1)) {
2075 Instruction *NOr = BinaryOperator::createOr(A, Op0, Op1->getName());
2077 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2080 // (A & C1)|(B & C2)
2081 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2082 match(Op1, m_And(m_Value(B), m_ConstantInt(C2)))) {
2084 if (A == B) // (A & C1)|(A & C2) == A & (C1|C2)
2085 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
2088 // If we have: ((V + N) & C1) | (V & C2)
2089 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
2090 // replace with V+N.
2091 if (C1 == ConstantExpr::getNot(C2)) {
2093 if ((C2->getRawValue() & (C2->getRawValue()+1)) == 0 && // C2 == 0+1+
2094 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
2095 // Add commutes, try both ways.
2096 if (V1 == B && MaskedValueIsZero(V2, C2))
2097 return ReplaceInstUsesWith(I, A);
2098 if (V2 == B && MaskedValueIsZero(V1, C2))
2099 return ReplaceInstUsesWith(I, A);
2101 // Or commutes, try both ways.
2102 if ((C1->getRawValue() & (C1->getRawValue()+1)) == 0 &&
2103 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
2104 // Add commutes, try both ways.
2105 if (V1 == A && MaskedValueIsZero(V2, C1))
2106 return ReplaceInstUsesWith(I, B);
2107 if (V2 == A && MaskedValueIsZero(V1, C1))
2108 return ReplaceInstUsesWith(I, B);
2113 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
2114 if (A == Op1) // ~A | A == -1
2115 return ReplaceInstUsesWith(I,
2116 ConstantIntegral::getAllOnesValue(I.getType()));
2120 // Note, A is still live here!
2121 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
2123 return ReplaceInstUsesWith(I,
2124 ConstantIntegral::getAllOnesValue(I.getType()));
2126 // (~A | ~B) == (~(A & B)) - De Morgan's Law
2127 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
2128 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
2129 I.getName()+".demorgan"), I);
2130 return BinaryOperator::createNot(And);
2134 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
2135 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
2136 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2139 Value *LHSVal, *RHSVal;
2140 ConstantInt *LHSCst, *RHSCst;
2141 Instruction::BinaryOps LHSCC, RHSCC;
2142 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
2143 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
2144 if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
2145 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
2146 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
2147 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
2148 // Ensure that the larger constant is on the RHS.
2149 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
2150 SetCondInst *LHS = cast<SetCondInst>(Op0);
2151 if (cast<ConstantBool>(Cmp)->getValue()) {
2152 std::swap(LHS, RHS);
2153 std::swap(LHSCst, RHSCst);
2154 std::swap(LHSCC, RHSCC);
2157 // At this point, we know we have have two setcc instructions
2158 // comparing a value against two constants and or'ing the result
2159 // together. Because of the above check, we know that we only have
2160 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
2161 // FoldSetCCLogical check above), that the two constants are not
2163 assert(LHSCst != RHSCst && "Compares not folded above?");
2166 default: assert(0 && "Unknown integer condition code!");
2167 case Instruction::SetEQ:
2169 default: assert(0 && "Unknown integer condition code!");
2170 case Instruction::SetEQ:
2171 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
2172 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2173 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
2174 LHSVal->getName()+".off");
2175 InsertNewInstBefore(Add, I);
2176 const Type *UnsType = Add->getType()->getUnsignedVersion();
2177 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
2178 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
2179 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2180 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
2182 break; // (X == 13 | X == 15) -> no change
2184 case Instruction::SetGT: // (X == 13 | X > 14) -> no change
2186 case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
2187 case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
2188 return ReplaceInstUsesWith(I, RHS);
2191 case Instruction::SetNE:
2193 default: assert(0 && "Unknown integer condition code!");
2194 case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
2195 case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
2196 return ReplaceInstUsesWith(I, LHS);
2197 case Instruction::SetNE: // (X != 13 | X != 15) -> true
2198 case Instruction::SetLT: // (X != 13 | X < 15) -> true
2199 return ReplaceInstUsesWith(I, ConstantBool::True);
2202 case Instruction::SetLT:
2204 default: assert(0 && "Unknown integer condition code!");
2205 case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
2207 case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
2208 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
2209 case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
2210 case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
2211 return ReplaceInstUsesWith(I, RHS);
2214 case Instruction::SetGT:
2216 default: assert(0 && "Unknown integer condition code!");
2217 case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
2218 case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
2219 return ReplaceInstUsesWith(I, LHS);
2220 case Instruction::SetNE: // (X > 13 | X != 15) -> true
2221 case Instruction::SetLT: // (X > 13 | X < 15) -> true
2222 return ReplaceInstUsesWith(I, ConstantBool::True);
2228 return Changed ? &I : 0;
2231 // XorSelf - Implements: X ^ X --> 0
2234 XorSelf(Value *rhs) : RHS(rhs) {}
2235 bool shouldApply(Value *LHS) const { return LHS == RHS; }
2236 Instruction *apply(BinaryOperator &Xor) const {
2242 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
2243 bool Changed = SimplifyCommutative(I);
2244 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2246 if (isa<UndefValue>(Op1))
2247 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
2249 // xor X, X = 0, even if X is nested in a sequence of Xor's.
2250 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
2251 assert(Result == &I && "AssociativeOpt didn't work?");
2252 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2255 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2257 if (RHS->isNullValue())
2258 return ReplaceInstUsesWith(I, Op0);
2260 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2261 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
2262 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
2263 if (RHS == ConstantBool::True && SCI->hasOneUse())
2264 return new SetCondInst(SCI->getInverseCondition(),
2265 SCI->getOperand(0), SCI->getOperand(1));
2267 // ~(c-X) == X-c-1 == X+(-c-1)
2268 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
2269 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
2270 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
2271 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
2272 ConstantInt::get(I.getType(), 1));
2273 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
2276 // ~(~X & Y) --> (X | ~Y)
2277 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
2278 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
2279 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
2281 BinaryOperator::createNot(Op0I->getOperand(1),
2282 Op0I->getOperand(1)->getName()+".not");
2283 InsertNewInstBefore(NotY, I);
2284 return BinaryOperator::createOr(Op0NotVal, NotY);
2288 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
2289 switch (Op0I->getOpcode()) {
2290 case Instruction::Add:
2291 // ~(X-c) --> (-c-1)-X
2292 if (RHS->isAllOnesValue()) {
2293 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
2294 return BinaryOperator::createSub(
2295 ConstantExpr::getSub(NegOp0CI,
2296 ConstantInt::get(I.getType(), 1)),
2297 Op0I->getOperand(0));
2300 case Instruction::And:
2301 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
2302 if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue())
2303 return BinaryOperator::createOr(Op0, RHS);
2305 case Instruction::Or:
2306 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
2307 if (ConstantExpr::getAnd(RHS, Op0CI) == RHS)
2308 return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS));
2314 // Try to fold constant and into select arguments.
2315 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2316 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2318 if (isa<PHINode>(Op0))
2319 if (Instruction *NV = FoldOpIntoPhi(I))
2323 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
2325 return ReplaceInstUsesWith(I,
2326 ConstantIntegral::getAllOnesValue(I.getType()));
2328 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
2330 return ReplaceInstUsesWith(I,
2331 ConstantIntegral::getAllOnesValue(I.getType()));
2333 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
2334 if (Op1I->getOpcode() == Instruction::Or) {
2335 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
2336 cast<BinaryOperator>(Op1I)->swapOperands();
2338 std::swap(Op0, Op1);
2339 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
2341 std::swap(Op0, Op1);
2343 } else if (Op1I->getOpcode() == Instruction::Xor) {
2344 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
2345 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
2346 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
2347 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
2350 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
2351 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
2352 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
2353 cast<BinaryOperator>(Op0I)->swapOperands();
2354 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
2355 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
2356 Op1->getName()+".not"), I);
2357 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
2359 } else if (Op0I->getOpcode() == Instruction::Xor) {
2360 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
2361 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2362 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
2363 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2366 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
2367 Value *A, *B; ConstantInt *C1, *C2;
2368 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2369 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) &&
2370 ConstantExpr::getAnd(C1, C2)->isNullValue())
2371 return BinaryOperator::createOr(Op0, Op1);
2373 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
2374 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
2375 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2378 return Changed ? &I : 0;
2381 /// MulWithOverflow - Compute Result = In1*In2, returning true if the result
2382 /// overflowed for this type.
2383 static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2385 Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
2386 return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
2389 static bool isPositive(ConstantInt *C) {
2390 return cast<ConstantSInt>(C)->getValue() >= 0;
2393 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
2394 /// overflowed for this type.
2395 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2397 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
2399 if (In1->getType()->isUnsigned())
2400 return cast<ConstantUInt>(Result)->getValue() <
2401 cast<ConstantUInt>(In1)->getValue();
2402 if (isPositive(In1) != isPositive(In2))
2404 if (isPositive(In1))
2405 return cast<ConstantSInt>(Result)->getValue() <
2406 cast<ConstantSInt>(In1)->getValue();
2407 return cast<ConstantSInt>(Result)->getValue() >
2408 cast<ConstantSInt>(In1)->getValue();
2411 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
2412 /// code necessary to compute the offset from the base pointer (without adding
2413 /// in the base pointer). Return the result as a signed integer of intptr size.
2414 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
2415 TargetData &TD = IC.getTargetData();
2416 gep_type_iterator GTI = gep_type_begin(GEP);
2417 const Type *UIntPtrTy = TD.getIntPtrType();
2418 const Type *SIntPtrTy = UIntPtrTy->getSignedVersion();
2419 Value *Result = Constant::getNullValue(SIntPtrTy);
2421 // Build a mask for high order bits.
2422 uint64_t PtrSizeMask = ~0ULL;
2423 PtrSizeMask >>= 64-(TD.getPointerSize()*8);
2425 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
2426 Value *Op = GEP->getOperand(i);
2427 uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask;
2428 Constant *Scale = ConstantExpr::getCast(ConstantUInt::get(UIntPtrTy, Size),
2430 if (Constant *OpC = dyn_cast<Constant>(Op)) {
2431 if (!OpC->isNullValue()) {
2432 OpC = ConstantExpr::getCast(OpC, SIntPtrTy);
2433 Scale = ConstantExpr::getMul(OpC, Scale);
2434 if (Constant *RC = dyn_cast<Constant>(Result))
2435 Result = ConstantExpr::getAdd(RC, Scale);
2437 // Emit an add instruction.
2438 Result = IC.InsertNewInstBefore(
2439 BinaryOperator::createAdd(Result, Scale,
2440 GEP->getName()+".offs"), I);
2444 // Convert to correct type.
2445 Op = IC.InsertNewInstBefore(new CastInst(Op, SIntPtrTy,
2446 Op->getName()+".c"), I);
2448 // We'll let instcombine(mul) convert this to a shl if possible.
2449 Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
2450 GEP->getName()+".idx"), I);
2452 // Emit an add instruction.
2453 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
2454 GEP->getName()+".offs"), I);
2460 /// FoldGEPSetCC - Fold comparisons between a GEP instruction and something
2461 /// else. At this point we know that the GEP is on the LHS of the comparison.
2462 Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS,
2463 Instruction::BinaryOps Cond,
2465 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
2467 if (CastInst *CI = dyn_cast<CastInst>(RHS))
2468 if (isa<PointerType>(CI->getOperand(0)->getType()))
2469 RHS = CI->getOperand(0);
2471 Value *PtrBase = GEPLHS->getOperand(0);
2472 if (PtrBase == RHS) {
2473 // As an optimization, we don't actually have to compute the actual value of
2474 // OFFSET if this is a seteq or setne comparison, just return whether each
2475 // index is zero or not.
2476 if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) {
2477 Instruction *InVal = 0;
2478 gep_type_iterator GTI = gep_type_begin(GEPLHS);
2479 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
2481 if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
2482 if (isa<UndefValue>(C)) // undef index -> undef.
2483 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
2484 if (C->isNullValue())
2486 else if (TD->getTypeSize(GTI.getIndexedType()) == 0) {
2487 EmitIt = false; // This is indexing into a zero sized array?
2488 } else if (isa<ConstantInt>(C))
2489 return ReplaceInstUsesWith(I, // No comparison is needed here.
2490 ConstantBool::get(Cond == Instruction::SetNE));
2495 new SetCondInst(Cond, GEPLHS->getOperand(i),
2496 Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
2500 InVal = InsertNewInstBefore(InVal, I);
2501 InsertNewInstBefore(Comp, I);
2502 if (Cond == Instruction::SetNE) // True if any are unequal
2503 InVal = BinaryOperator::createOr(InVal, Comp);
2504 else // True if all are equal
2505 InVal = BinaryOperator::createAnd(InVal, Comp);
2513 ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0
2514 ConstantBool::get(Cond == Instruction::SetEQ));
2517 // Only lower this if the setcc is the only user of the GEP or if we expect
2518 // the result to fold to a constant!
2519 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
2520 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
2521 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
2522 return new SetCondInst(Cond, Offset,
2523 Constant::getNullValue(Offset->getType()));
2525 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
2526 // If the base pointers are different, but the indices are the same, just
2527 // compare the base pointer.
2528 if (PtrBase != GEPRHS->getOperand(0)) {
2529 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
2530 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
2531 GEPRHS->getOperand(0)->getType();
2533 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2534 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2535 IndicesTheSame = false;
2539 // If all indices are the same, just compare the base pointers.
2541 return new SetCondInst(Cond, GEPLHS->getOperand(0),
2542 GEPRHS->getOperand(0));
2544 // Otherwise, the base pointers are different and the indices are
2545 // different, bail out.
2549 // If one of the GEPs has all zero indices, recurse.
2550 bool AllZeros = true;
2551 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2552 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
2553 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
2558 return FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0),
2559 SetCondInst::getSwappedCondition(Cond), I);
2561 // If the other GEP has all zero indices, recurse.
2563 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2564 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
2565 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
2570 return FoldGEPSetCC(GEPLHS, GEPRHS->getOperand(0), Cond, I);
2572 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
2573 // If the GEPs only differ by one index, compare it.
2574 unsigned NumDifferences = 0; // Keep track of # differences.
2575 unsigned DiffOperand = 0; // The operand that differs.
2576 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2577 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2578 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
2579 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
2580 // Irreconcilable differences.
2584 if (NumDifferences++) break;
2589 if (NumDifferences == 0) // SAME GEP?
2590 return ReplaceInstUsesWith(I, // No comparison is needed here.
2591 ConstantBool::get(Cond == Instruction::SetEQ));
2592 else if (NumDifferences == 1) {
2593 Value *LHSV = GEPLHS->getOperand(DiffOperand);
2594 Value *RHSV = GEPRHS->getOperand(DiffOperand);
2596 // Convert the operands to signed values to make sure to perform a
2597 // signed comparison.
2598 const Type *NewTy = LHSV->getType()->getSignedVersion();
2599 if (LHSV->getType() != NewTy)
2600 LHSV = InsertNewInstBefore(new CastInst(LHSV, NewTy,
2601 LHSV->getName()), I);
2602 if (RHSV->getType() != NewTy)
2603 RHSV = InsertNewInstBefore(new CastInst(RHSV, NewTy,
2604 RHSV->getName()), I);
2605 return new SetCondInst(Cond, LHSV, RHSV);
2609 // Only lower this if the setcc is the only user of the GEP or if we expect
2610 // the result to fold to a constant!
2611 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
2612 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
2613 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
2614 Value *L = EmitGEPOffset(GEPLHS, I, *this);
2615 Value *R = EmitGEPOffset(GEPRHS, I, *this);
2616 return new SetCondInst(Cond, L, R);
2623 Instruction *InstCombiner::visitSetCondInst(SetCondInst &I) {
2624 bool Changed = SimplifyCommutative(I);
2625 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2626 const Type *Ty = Op0->getType();
2630 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
2632 if (isa<UndefValue>(Op1)) // X setcc undef -> undef
2633 return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
2635 // setcc <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
2636 // addresses never equal each other! We already know that Op0 != Op1.
2637 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
2638 isa<ConstantPointerNull>(Op0)) &&
2639 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
2640 isa<ConstantPointerNull>(Op1)))
2641 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
2643 // setcc's with boolean values can always be turned into bitwise operations
2644 if (Ty == Type::BoolTy) {
2645 switch (I.getOpcode()) {
2646 default: assert(0 && "Invalid setcc instruction!");
2647 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
2648 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
2649 InsertNewInstBefore(Xor, I);
2650 return BinaryOperator::createNot(Xor);
2652 case Instruction::SetNE:
2653 return BinaryOperator::createXor(Op0, Op1);
2655 case Instruction::SetGT:
2656 std::swap(Op0, Op1); // Change setgt -> setlt
2658 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
2659 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2660 InsertNewInstBefore(Not, I);
2661 return BinaryOperator::createAnd(Not, Op1);
2663 case Instruction::SetGE:
2664 std::swap(Op0, Op1); // Change setge -> setle
2666 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
2667 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2668 InsertNewInstBefore(Not, I);
2669 return BinaryOperator::createOr(Not, Op1);
2674 // See if we are doing a comparison between a constant and an instruction that
2675 // can be folded into the comparison.
2676 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2677 // Check to see if we are comparing against the minimum or maximum value...
2678 if (CI->isMinValue()) {
2679 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
2680 return ReplaceInstUsesWith(I, ConstantBool::False);
2681 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
2682 return ReplaceInstUsesWith(I, ConstantBool::True);
2683 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
2684 return BinaryOperator::createSetEQ(Op0, Op1);
2685 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
2686 return BinaryOperator::createSetNE(Op0, Op1);
2688 } else if (CI->isMaxValue()) {
2689 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
2690 return ReplaceInstUsesWith(I, ConstantBool::False);
2691 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
2692 return ReplaceInstUsesWith(I, ConstantBool::True);
2693 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
2694 return BinaryOperator::createSetEQ(Op0, Op1);
2695 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
2696 return BinaryOperator::createSetNE(Op0, Op1);
2698 // Comparing against a value really close to min or max?
2699 } else if (isMinValuePlusOne(CI)) {
2700 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
2701 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
2702 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
2703 return BinaryOperator::createSetNE(Op0, SubOne(CI));
2705 } else if (isMaxValueMinusOne(CI)) {
2706 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
2707 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
2708 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
2709 return BinaryOperator::createSetNE(Op0, AddOne(CI));
2712 // If we still have a setle or setge instruction, turn it into the
2713 // appropriate setlt or setgt instruction. Since the border cases have
2714 // already been handled above, this requires little checking.
2716 if (I.getOpcode() == Instruction::SetLE)
2717 return BinaryOperator::createSetLT(Op0, AddOne(CI));
2718 if (I.getOpcode() == Instruction::SetGE)
2719 return BinaryOperator::createSetGT(Op0, SubOne(CI));
2721 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
2722 switch (LHSI->getOpcode()) {
2723 case Instruction::And:
2724 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
2725 LHSI->getOperand(0)->hasOneUse()) {
2726 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
2727 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
2728 // happens a LOT in code produced by the C front-end, for bitfield
2730 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
2731 ConstantUInt *ShAmt;
2732 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
2733 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
2734 const Type *Ty = LHSI->getType();
2736 // We can fold this as long as we can't shift unknown bits
2737 // into the mask. This can only happen with signed shift
2738 // rights, as they sign-extend.
2740 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
2741 Shift->getType()->isUnsigned();
2743 // To test for the bad case of the signed shr, see if any
2744 // of the bits shifted in could be tested after the mask.
2745 int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue();
2746 if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
2748 Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal);
2750 ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
2751 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
2757 if (Shift->getOpcode() == Instruction::Shl)
2758 NewCst = ConstantExpr::getUShr(CI, ShAmt);
2760 NewCst = ConstantExpr::getShl(CI, ShAmt);
2762 // Check to see if we are shifting out any of the bits being
2764 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
2765 // If we shifted bits out, the fold is not going to work out.
2766 // As a special case, check to see if this means that the
2767 // result is always true or false now.
2768 if (I.getOpcode() == Instruction::SetEQ)
2769 return ReplaceInstUsesWith(I, ConstantBool::False);
2770 if (I.getOpcode() == Instruction::SetNE)
2771 return ReplaceInstUsesWith(I, ConstantBool::True);
2773 I.setOperand(1, NewCst);
2774 Constant *NewAndCST;
2775 if (Shift->getOpcode() == Instruction::Shl)
2776 NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
2778 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
2779 LHSI->setOperand(1, NewAndCST);
2780 LHSI->setOperand(0, Shift->getOperand(0));
2781 WorkList.push_back(Shift); // Shift is dead.
2782 AddUsesToWorkList(I);
2790 case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
2791 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2792 switch (I.getOpcode()) {
2794 case Instruction::SetEQ:
2795 case Instruction::SetNE: {
2796 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2798 // Check that the shift amount is in range. If not, don't perform
2799 // undefined shifts. When the shift is visited it will be
2801 if (ShAmt->getValue() >= TypeBits)
2804 // If we are comparing against bits always shifted out, the
2805 // comparison cannot succeed.
2807 ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
2808 if (Comp != CI) {// Comparing against a bit that we know is zero.
2809 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2810 Constant *Cst = ConstantBool::get(IsSetNE);
2811 return ReplaceInstUsesWith(I, Cst);
2814 if (LHSI->hasOneUse()) {
2815 // Otherwise strength reduce the shift into an and.
2816 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2817 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
2820 if (CI->getType()->isUnsigned()) {
2821 Mask = ConstantUInt::get(CI->getType(), Val);
2822 } else if (ShAmtVal != 0) {
2823 Mask = ConstantSInt::get(CI->getType(), Val);
2825 Mask = ConstantInt::getAllOnesValue(CI->getType());
2829 BinaryOperator::createAnd(LHSI->getOperand(0),
2830 Mask, LHSI->getName()+".mask");
2831 Value *And = InsertNewInstBefore(AndI, I);
2832 return new SetCondInst(I.getOpcode(), And,
2833 ConstantExpr::getUShr(CI, ShAmt));
2840 case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
2841 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2842 switch (I.getOpcode()) {
2844 case Instruction::SetEQ:
2845 case Instruction::SetNE: {
2847 // Check that the shift amount is in range. If not, don't perform
2848 // undefined shifts. When the shift is visited it will be
2850 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2851 if (ShAmt->getValue() >= TypeBits)
2854 // If we are comparing against bits always shifted out, the
2855 // comparison cannot succeed.
2857 ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
2859 if (Comp != CI) {// Comparing against a bit that we know is zero.
2860 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2861 Constant *Cst = ConstantBool::get(IsSetNE);
2862 return ReplaceInstUsesWith(I, Cst);
2865 if (LHSI->hasOneUse() || CI->isNullValue()) {
2866 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2868 // Otherwise strength reduce the shift into an and.
2869 uint64_t Val = ~0ULL; // All ones.
2870 Val <<= ShAmtVal; // Shift over to the right spot.
2873 if (CI->getType()->isUnsigned()) {
2874 Val &= ~0ULL >> (64-TypeBits);
2875 Mask = ConstantUInt::get(CI->getType(), Val);
2877 Mask = ConstantSInt::get(CI->getType(), Val);
2881 BinaryOperator::createAnd(LHSI->getOperand(0),
2882 Mask, LHSI->getName()+".mask");
2883 Value *And = InsertNewInstBefore(AndI, I);
2884 return new SetCondInst(I.getOpcode(), And,
2885 ConstantExpr::getShl(CI, ShAmt));
2893 case Instruction::Div:
2894 // Fold: (div X, C1) op C2 -> range check
2895 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
2896 // Fold this div into the comparison, producing a range check.
2897 // Determine, based on the divide type, what the range is being
2898 // checked. If there is an overflow on the low or high side, remember
2899 // it, otherwise compute the range [low, hi) bounding the new value.
2900 bool LoOverflow = false, HiOverflow = 0;
2901 ConstantInt *LoBound = 0, *HiBound = 0;
2904 bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
2906 Instruction::BinaryOps Opcode = I.getOpcode();
2908 if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
2909 } else if (LHSI->getType()->isUnsigned()) { // udiv
2911 LoOverflow = ProdOV;
2912 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
2913 } else if (isPositive(DivRHS)) { // Divisor is > 0.
2914 if (CI->isNullValue()) { // (X / pos) op 0
2916 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
2918 } else if (isPositive(CI)) { // (X / pos) op pos
2920 LoOverflow = ProdOV;
2921 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
2922 } else { // (X / pos) op neg
2923 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
2924 LoOverflow = AddWithOverflow(LoBound, Prod,
2925 cast<ConstantInt>(DivRHSH));
2927 HiOverflow = ProdOV;
2929 } else { // Divisor is < 0.
2930 if (CI->isNullValue()) { // (X / neg) op 0
2931 LoBound = AddOne(DivRHS);
2932 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
2933 if (HiBound == DivRHS)
2934 LoBound = 0; // - INTMIN = INTMIN
2935 } else if (isPositive(CI)) { // (X / neg) op pos
2936 HiOverflow = LoOverflow = ProdOV;
2938 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
2939 HiBound = AddOne(Prod);
2940 } else { // (X / neg) op neg
2942 LoOverflow = HiOverflow = ProdOV;
2943 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
2946 // Dividing by a negate swaps the condition.
2947 Opcode = SetCondInst::getSwappedCondition(Opcode);
2951 Value *X = LHSI->getOperand(0);
2953 default: assert(0 && "Unhandled setcc opcode!");
2954 case Instruction::SetEQ:
2955 if (LoOverflow && HiOverflow)
2956 return ReplaceInstUsesWith(I, ConstantBool::False);
2957 else if (HiOverflow)
2958 return new SetCondInst(Instruction::SetGE, X, LoBound);
2959 else if (LoOverflow)
2960 return new SetCondInst(Instruction::SetLT, X, HiBound);
2962 return InsertRangeTest(X, LoBound, HiBound, true, I);
2963 case Instruction::SetNE:
2964 if (LoOverflow && HiOverflow)
2965 return ReplaceInstUsesWith(I, ConstantBool::True);
2966 else if (HiOverflow)
2967 return new SetCondInst(Instruction::SetLT, X, LoBound);
2968 else if (LoOverflow)
2969 return new SetCondInst(Instruction::SetGE, X, HiBound);
2971 return InsertRangeTest(X, LoBound, HiBound, false, I);
2972 case Instruction::SetLT:
2974 return ReplaceInstUsesWith(I, ConstantBool::False);
2975 return new SetCondInst(Instruction::SetLT, X, LoBound);
2976 case Instruction::SetGT:
2978 return ReplaceInstUsesWith(I, ConstantBool::False);
2979 return new SetCondInst(Instruction::SetGE, X, HiBound);
2986 // Simplify seteq and setne instructions...
2987 if (I.getOpcode() == Instruction::SetEQ ||
2988 I.getOpcode() == Instruction::SetNE) {
2989 bool isSetNE = I.getOpcode() == Instruction::SetNE;
2991 // If the first operand is (and|or|xor) with a constant, and the second
2992 // operand is a constant, simplify a bit.
2993 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
2994 switch (BO->getOpcode()) {
2995 case Instruction::Rem:
2996 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
2997 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
2999 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1) {
3000 int64_t V = cast<ConstantSInt>(BO->getOperand(1))->getValue();
3001 if (isPowerOf2_64(V)) {
3002 unsigned L2 = Log2_64(V);
3003 const Type *UTy = BO->getType()->getUnsignedVersion();
3004 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
3006 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
3007 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
3008 RHSCst, BO->getName()), I);
3009 return BinaryOperator::create(I.getOpcode(), NewRem,
3010 Constant::getNullValue(UTy));
3015 case Instruction::Add:
3016 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
3017 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3018 if (BO->hasOneUse())
3019 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
3020 ConstantExpr::getSub(CI, BOp1C));
3021 } else if (CI->isNullValue()) {
3022 // Replace ((add A, B) != 0) with (A != -B) if A or B is
3023 // efficiently invertible, or if the add has just this one use.
3024 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
3026 if (Value *NegVal = dyn_castNegVal(BOp1))
3027 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
3028 else if (Value *NegVal = dyn_castNegVal(BOp0))
3029 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
3030 else if (BO->hasOneUse()) {
3031 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
3033 InsertNewInstBefore(Neg, I);
3034 return new SetCondInst(I.getOpcode(), BOp0, Neg);
3038 case Instruction::Xor:
3039 // For the xor case, we can xor two constants together, eliminating
3040 // the explicit xor.
3041 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
3042 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
3043 ConstantExpr::getXor(CI, BOC));
3046 case Instruction::Sub:
3047 // Replace (([sub|xor] A, B) != 0) with (A != B)
3048 if (CI->isNullValue())
3049 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
3053 case Instruction::Or:
3054 // If bits are being or'd in that are not present in the constant we
3055 // are comparing against, then the comparison could never succeed!
3056 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
3057 Constant *NotCI = ConstantExpr::getNot(CI);
3058 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
3059 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3063 case Instruction::And:
3064 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3065 // If bits are being compared against that are and'd out, then the
3066 // comparison can never succeed!
3067 if (!ConstantExpr::getAnd(CI,
3068 ConstantExpr::getNot(BOC))->isNullValue())
3069 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3071 // If we have ((X & C) == C), turn it into ((X & C) != 0).
3072 if (CI == BOC && isOneBitSet(CI))
3073 return new SetCondInst(isSetNE ? Instruction::SetEQ :
3074 Instruction::SetNE, Op0,
3075 Constant::getNullValue(CI->getType()));
3077 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
3078 // to be a signed value as appropriate.
3079 if (isSignBit(BOC)) {
3080 Value *X = BO->getOperand(0);
3081 // If 'X' is not signed, insert a cast now...
3082 if (!BOC->getType()->isSigned()) {
3083 const Type *DestTy = BOC->getType()->getSignedVersion();
3084 X = InsertCastBefore(X, DestTy, I);
3086 return new SetCondInst(isSetNE ? Instruction::SetLT :
3087 Instruction::SetGE, X,
3088 Constant::getNullValue(X->getType()));
3091 // ((X & ~7) == 0) --> X < 8
3092 if (CI->isNullValue() && isHighOnes(BOC)) {
3093 Value *X = BO->getOperand(0);
3094 Constant *NegX = ConstantExpr::getNeg(BOC);
3096 // If 'X' is signed, insert a cast now.
3097 if (NegX->getType()->isSigned()) {
3098 const Type *DestTy = NegX->getType()->getUnsignedVersion();
3099 X = InsertCastBefore(X, DestTy, I);
3100 NegX = ConstantExpr::getCast(NegX, DestTy);
3103 return new SetCondInst(isSetNE ? Instruction::SetGE :
3104 Instruction::SetLT, X, NegX);
3111 } else { // Not a SetEQ/SetNE
3112 // If the LHS is a cast from an integral value of the same size,
3113 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
3114 Value *CastOp = Cast->getOperand(0);
3115 const Type *SrcTy = CastOp->getType();
3116 unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits();
3117 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
3118 SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
3119 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
3120 "Source and destination signednesses should differ!");
3121 if (Cast->getType()->isSigned()) {
3122 // If this is a signed comparison, check for comparisons in the
3123 // vicinity of zero.
3124 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
3126 return BinaryOperator::createSetGT(CastOp,
3127 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize-1))-1));
3128 else if (I.getOpcode() == Instruction::SetGT &&
3129 cast<ConstantSInt>(CI)->getValue() == -1)
3130 // X > -1 => x < 128
3131 return BinaryOperator::createSetLT(CastOp,
3132 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize-1)));
3134 ConstantUInt *CUI = cast<ConstantUInt>(CI);
3135 if (I.getOpcode() == Instruction::SetLT &&
3136 CUI->getValue() == 1ULL << (SrcTySize-1))
3137 // X < 128 => X > -1
3138 return BinaryOperator::createSetGT(CastOp,
3139 ConstantSInt::get(SrcTy, -1));
3140 else if (I.getOpcode() == Instruction::SetGT &&
3141 CUI->getValue() == (1ULL << (SrcTySize-1))-1)
3143 return BinaryOperator::createSetLT(CastOp,
3144 Constant::getNullValue(SrcTy));
3151 // Handle setcc with constant RHS's that can be integer, FP or pointer.
3152 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
3153 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3154 switch (LHSI->getOpcode()) {
3155 case Instruction::GetElementPtr:
3156 if (RHSC->isNullValue()) {
3157 // Transform setcc GEP P, int 0, int 0, int 0, null -> setcc P, null
3158 bool isAllZeros = true;
3159 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
3160 if (!isa<Constant>(LHSI->getOperand(i)) ||
3161 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
3166 return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),
3167 Constant::getNullValue(LHSI->getOperand(0)->getType()));
3171 case Instruction::PHI:
3172 if (Instruction *NV = FoldOpIntoPhi(I))
3175 case Instruction::Select:
3176 // If either operand of the select is a constant, we can fold the
3177 // comparison into the select arms, which will cause one to be
3178 // constant folded and the select turned into a bitwise or.
3179 Value *Op1 = 0, *Op2 = 0;
3180 if (LHSI->hasOneUse()) {
3181 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
3182 // Fold the known value into the constant operand.
3183 Op1 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3184 // Insert a new SetCC of the other select operand.
3185 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3186 LHSI->getOperand(2), RHSC,
3188 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
3189 // Fold the known value into the constant operand.
3190 Op2 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3191 // Insert a new SetCC of the other select operand.
3192 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3193 LHSI->getOperand(1), RHSC,
3199 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
3204 // If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now.
3205 if (User *GEP = dyn_castGetElementPtr(Op0))
3206 if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I))
3208 if (User *GEP = dyn_castGetElementPtr(Op1))
3209 if (Instruction *NI = FoldGEPSetCC(GEP, Op0,
3210 SetCondInst::getSwappedCondition(I.getOpcode()), I))
3213 // Test to see if the operands of the setcc are casted versions of other
3214 // values. If the cast can be stripped off both arguments, we do so now.
3215 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3216 Value *CastOp0 = CI->getOperand(0);
3217 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
3218 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
3219 (I.getOpcode() == Instruction::SetEQ ||
3220 I.getOpcode() == Instruction::SetNE)) {
3221 // We keep moving the cast from the left operand over to the right
3222 // operand, where it can often be eliminated completely.
3225 // If operand #1 is a cast instruction, see if we can eliminate it as
3227 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
3228 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
3230 Op1 = CI2->getOperand(0);
3232 // If Op1 is a constant, we can fold the cast into the constant.
3233 if (Op1->getType() != Op0->getType())
3234 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
3235 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
3237 // Otherwise, cast the RHS right before the setcc
3238 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
3239 InsertNewInstBefore(cast<Instruction>(Op1), I);
3241 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
3244 // Handle the special case of: setcc (cast bool to X), <cst>
3245 // This comes up when you have code like
3248 // For generality, we handle any zero-extension of any operand comparison
3249 // with a constant or another cast from the same type.
3250 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
3251 if (Instruction *R = visitSetCondInstWithCastAndCast(I))
3254 return Changed ? &I : 0;
3257 // visitSetCondInstWithCastAndCast - Handle setcond (cast x to y), (cast/cst).
3258 // We only handle extending casts so far.
3260 Instruction *InstCombiner::visitSetCondInstWithCastAndCast(SetCondInst &SCI) {
3261 Value *LHSCIOp = cast<CastInst>(SCI.getOperand(0))->getOperand(0);
3262 const Type *SrcTy = LHSCIOp->getType();
3263 const Type *DestTy = SCI.getOperand(0)->getType();
3266 if (!DestTy->isIntegral() || !SrcTy->isIntegral())
3269 unsigned SrcBits = SrcTy->getPrimitiveSizeInBits();
3270 unsigned DestBits = DestTy->getPrimitiveSizeInBits();
3271 if (SrcBits >= DestBits) return 0; // Only handle extending cast.
3273 // Is this a sign or zero extension?
3274 bool isSignSrc = SrcTy->isSigned();
3275 bool isSignDest = DestTy->isSigned();
3277 if (CastInst *CI = dyn_cast<CastInst>(SCI.getOperand(1))) {
3278 // Not an extension from the same type?
3279 RHSCIOp = CI->getOperand(0);
3280 if (RHSCIOp->getType() != LHSCIOp->getType()) return 0;
3281 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(SCI.getOperand(1))) {
3282 // Compute the constant that would happen if we truncated to SrcTy then
3283 // reextended to DestTy.
3284 Constant *Res = ConstantExpr::getCast(CI, SrcTy);
3286 if (ConstantExpr::getCast(Res, DestTy) == CI) {
3289 // If the value cannot be represented in the shorter type, we cannot emit
3290 // a simple comparison.
3291 if (SCI.getOpcode() == Instruction::SetEQ)
3292 return ReplaceInstUsesWith(SCI, ConstantBool::False);
3293 if (SCI.getOpcode() == Instruction::SetNE)
3294 return ReplaceInstUsesWith(SCI, ConstantBool::True);
3296 // Evaluate the comparison for LT.
3298 if (DestTy->isSigned()) {
3299 // We're performing a signed comparison.
3301 // Signed extend and signed comparison.
3302 if (cast<ConstantSInt>(CI)->getValue() < 0) // X < (small) --> false
3303 Result = ConstantBool::False;
3305 Result = ConstantBool::True; // X < (large) --> true
3307 // Unsigned extend and signed comparison.
3308 if (cast<ConstantSInt>(CI)->getValue() < 0)
3309 Result = ConstantBool::False;
3311 Result = ConstantBool::True;
3314 // We're performing an unsigned comparison.
3316 // Unsigned extend & compare -> always true.
3317 Result = ConstantBool::True;
3319 // We're performing an unsigned comp with a sign extended value.
3320 // This is true if the input is >= 0. [aka >s -1]
3321 Constant *NegOne = ConstantIntegral::getAllOnesValue(SrcTy);
3322 Result = InsertNewInstBefore(BinaryOperator::createSetGT(LHSCIOp,
3323 NegOne, SCI.getName()), SCI);
3327 // Finally, return the value computed.
3328 if (SCI.getOpcode() == Instruction::SetLT) {
3329 return ReplaceInstUsesWith(SCI, Result);
3331 assert(SCI.getOpcode()==Instruction::SetGT &&"SetCC should be folded!");
3332 if (Constant *CI = dyn_cast<Constant>(Result))
3333 return ReplaceInstUsesWith(SCI, ConstantExpr::getNot(CI));
3335 return BinaryOperator::createNot(Result);
3342 // Okay, just insert a compare of the reduced operands now!
3343 return BinaryOperator::create(SCI.getOpcode(), LHSCIOp, RHSCIOp);
3346 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
3347 assert(I.getOperand(1)->getType() == Type::UByteTy);
3348 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3349 bool isLeftShift = I.getOpcode() == Instruction::Shl;
3351 // shl X, 0 == X and shr X, 0 == X
3352 // shl 0, X == 0 and shr 0, X == 0
3353 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
3354 Op0 == Constant::getNullValue(Op0->getType()))
3355 return ReplaceInstUsesWith(I, Op0);
3357 if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
3358 if (!isLeftShift && I.getType()->isSigned())
3359 return ReplaceInstUsesWith(I, Op0);
3360 else // undef << X -> 0 AND undef >>u X -> 0
3361 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3363 if (isa<UndefValue>(Op1)) {
3364 if (isLeftShift || I.getType()->isUnsigned())// X << undef, X >>u undef -> 0
3365 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3367 return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X
3370 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
3372 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
3373 if (CSI->isAllOnesValue())
3374 return ReplaceInstUsesWith(I, CSI);
3376 // Try to fold constant and into select arguments.
3377 if (isa<Constant>(Op0))
3378 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
3379 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3382 // See if we can turn a signed shr into an unsigned shr.
3383 if (!isLeftShift && I.getType()->isSigned()) {
3384 if (MaskedValueIsZero(Op0, ConstantInt::getMinValue(I.getType()))) {
3385 Value *V = InsertCastBefore(Op0, I.getType()->getUnsignedVersion(), I);
3386 V = InsertNewInstBefore(new ShiftInst(Instruction::Shr, V, Op1,
3388 return new CastInst(V, I.getType());
3392 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
3393 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
3394 // of a signed value.
3396 unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits();
3397 if (CUI->getValue() >= TypeBits) {
3398 if (!Op0->getType()->isSigned() || isLeftShift)
3399 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
3401 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
3406 // ((X*C1) << C2) == (X * (C1 << C2))
3407 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
3408 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
3409 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
3410 return BinaryOperator::createMul(BO->getOperand(0),
3411 ConstantExpr::getShl(BOOp, CUI));
3413 // Try to fold constant and into select arguments.
3414 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3415 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3417 if (isa<PHINode>(Op0))
3418 if (Instruction *NV = FoldOpIntoPhi(I))
3421 if (Op0->hasOneUse()) {
3422 // If this is a SHL of a sign-extending cast, see if we can turn the input
3423 // into a zero extending cast (a simple strength reduction).
3424 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3425 const Type *SrcTy = CI->getOperand(0)->getType();
3426 if (isLeftShift && SrcTy->isInteger() && SrcTy->isSigned() &&
3427 SrcTy->getPrimitiveSizeInBits() <
3428 CI->getType()->getPrimitiveSizeInBits()) {
3429 // We can change it to a zero extension if we are shifting out all of
3430 // the sign extended bits. To check this, form a mask of all of the
3431 // sign extend bits, then shift them left and see if we have anything
3433 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); // 1111
3434 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); // 00001111
3435 Mask = ConstantExpr::getNot(Mask); // 1's in the sign bits: 11110000
3436 if (ConstantExpr::getShl(Mask, CUI)->isNullValue()) {
3437 // If the shift is nuking all of the sign bits, change this to a
3438 // zero extension cast. To do this, cast the cast input to
3439 // unsigned, then to the requested size.
3440 Value *CastOp = CI->getOperand(0);
3442 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
3443 CI->getName()+".uns");
3444 NC = InsertNewInstBefore(NC, I);
3445 // Finally, insert a replacement for CI.
3446 NC = new CastInst(NC, CI->getType(), CI->getName());
3448 NC = InsertNewInstBefore(NC, I);
3449 WorkList.push_back(CI); // Delete CI later.
3450 I.setOperand(0, NC);
3451 return &I; // The SHL operand was modified.
3456 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
3457 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
3460 switch (Op0BO->getOpcode()) {
3462 case Instruction::Add:
3463 case Instruction::And:
3464 case Instruction::Or:
3465 case Instruction::Xor:
3466 // These operators commute.
3467 // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
3468 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
3469 match(Op0BO->getOperand(1),
3470 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == CUI) {
3471 Instruction *YS = new ShiftInst(Instruction::Shl,
3472 Op0BO->getOperand(0), CUI,
3474 InsertNewInstBefore(YS, I); // (Y << C)
3475 Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
3477 Op0BO->getOperand(1)->getName());
3478 InsertNewInstBefore(X, I); // (X + (Y << C))
3479 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
3480 C2 = ConstantExpr::getShl(C2, CUI);
3481 return BinaryOperator::createAnd(X, C2);
3484 // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
3485 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
3486 match(Op0BO->getOperand(1),
3487 m_And(m_Shr(m_Value(V1), m_Value(V2)),
3488 m_ConstantInt(CC))) && V2 == CUI &&
3489 cast<BinaryOperator>(Op0BO->getOperand(1))->getOperand(0)->hasOneUse()) {
3490 Instruction *YS = new ShiftInst(Instruction::Shl,
3491 Op0BO->getOperand(0), CUI,
3493 InsertNewInstBefore(YS, I); // (Y << C)
3495 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, CUI),
3496 V1->getName()+".mask");
3497 InsertNewInstBefore(XM, I); // X & (CC << C)
3499 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
3503 case Instruction::Sub:
3504 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
3505 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
3506 match(Op0BO->getOperand(0),
3507 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == CUI) {
3508 Instruction *YS = new ShiftInst(Instruction::Shl,
3509 Op0BO->getOperand(1), CUI,
3511 InsertNewInstBefore(YS, I); // (Y << C)
3512 Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
3514 Op0BO->getOperand(0)->getName());
3515 InsertNewInstBefore(X, I); // (X + (Y << C))
3516 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
3517 C2 = ConstantExpr::getShl(C2, CUI);
3518 return BinaryOperator::createAnd(X, C2);
3521 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
3522 match(Op0BO->getOperand(0),
3523 m_And(m_Shr(m_Value(V1), m_Value(V2)),
3524 m_ConstantInt(CC))) && V2 == CUI &&
3525 cast<BinaryOperator>(Op0BO->getOperand(0))->getOperand(0)->hasOneUse()) {
3526 Instruction *YS = new ShiftInst(Instruction::Shl,
3527 Op0BO->getOperand(1), CUI,
3529 InsertNewInstBefore(YS, I); // (Y << C)
3531 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, CUI),
3532 V1->getName()+".mask");
3533 InsertNewInstBefore(XM, I); // X & (CC << C)
3535 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
3542 // If the operand is an bitwise operator with a constant RHS, and the
3543 // shift is the only use, we can pull it out of the shift.
3544 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
3545 bool isValid = true; // Valid only for And, Or, Xor
3546 bool highBitSet = false; // Transform if high bit of constant set?
3548 switch (Op0BO->getOpcode()) {
3549 default: isValid = false; break; // Do not perform transform!
3550 case Instruction::Add:
3551 isValid = isLeftShift;
3553 case Instruction::Or:
3554 case Instruction::Xor:
3557 case Instruction::And:
3562 // If this is a signed shift right, and the high bit is modified
3563 // by the logical operation, do not perform the transformation.
3564 // The highBitSet boolean indicates the value of the high bit of
3565 // the constant which would cause it to be modified for this
3568 if (isValid && !isLeftShift && !I.getType()->isUnsigned()) {
3569 uint64_t Val = Op0C->getRawValue();
3570 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
3574 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI);
3576 Instruction *NewShift =
3577 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI,
3580 InsertNewInstBefore(NewShift, I);
3582 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
3589 // If this is a shift of a shift, see if we can fold the two together...
3590 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
3591 if (ConstantUInt *ShiftAmt1C =
3592 dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) {
3593 unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getValue();
3594 unsigned ShiftAmt2 = (unsigned)CUI->getValue();
3596 // Check for (A << c1) << c2 and (A >> c1) >> c2
3597 if (I.getOpcode() == Op0SI->getOpcode()) {
3598 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
3599 if (Op0->getType()->getPrimitiveSizeInBits() < Amt)
3600 Amt = Op0->getType()->getPrimitiveSizeInBits();
3601 return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
3602 ConstantUInt::get(Type::UByteTy, Amt));
3605 // Check for (A << c1) >> c2 or visaversa. If we are dealing with
3606 // signed types, we can only support the (A >> c1) << c2 configuration,
3607 // because it can not turn an arbitrary bit of A into a sign bit.
3608 if (I.getType()->isUnsigned() || isLeftShift) {
3609 // Calculate bitmask for what gets shifted off the edge...
3610 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
3612 C = ConstantExpr::getShl(C, ShiftAmt1C);
3614 C = ConstantExpr::getShr(C, ShiftAmt1C);
3617 BinaryOperator::createAnd(Op0SI->getOperand(0), C,
3618 Op0SI->getOperand(0)->getName()+".mask");
3619 InsertNewInstBefore(Mask, I);
3621 // Figure out what flavor of shift we should use...
3622 if (ShiftAmt1 == ShiftAmt2)
3623 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
3624 else if (ShiftAmt1 < ShiftAmt2) {
3625 return new ShiftInst(I.getOpcode(), Mask,
3626 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
3628 return new ShiftInst(Op0SI->getOpcode(), Mask,
3629 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
3632 // We can handle signed (X << C1) >> C2 if it's a sign extend. In
3633 // this case, C1 == C2 and C1 is 8, 16, or 32.
3634 if (ShiftAmt1 == ShiftAmt2) {
3635 const Type *SExtType = 0;
3636 switch (ShiftAmt1) {
3637 case 8 : SExtType = Type::SByteTy; break;
3638 case 16: SExtType = Type::ShortTy; break;
3639 case 32: SExtType = Type::IntTy; break;
3643 Instruction *NewTrunc = new CastInst(Op0SI->getOperand(0),
3645 InsertNewInstBefore(NewTrunc, I);
3646 return new CastInst(NewTrunc, I.getType());
3663 /// getCastType - In the future, we will split the cast instruction into these
3664 /// various types. Until then, we have to do the analysis here.
3665 static CastType getCastType(const Type *Src, const Type *Dest) {
3666 assert(Src->isIntegral() && Dest->isIntegral() &&
3667 "Only works on integral types!");
3668 unsigned SrcSize = Src->getPrimitiveSizeInBits();
3669 unsigned DestSize = Dest->getPrimitiveSizeInBits();
3671 if (SrcSize == DestSize) return Noop;
3672 if (SrcSize > DestSize) return Truncate;
3673 if (Src->isSigned()) return Signext;
3678 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
3681 static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
3682 const Type *DstTy, TargetData *TD) {
3684 // It is legal to eliminate the instruction if casting A->B->A if the sizes
3685 // are identical and the bits don't get reinterpreted (for example
3686 // int->float->int would not be allowed).
3687 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
3690 // If we are casting between pointer and integer types, treat pointers as
3691 // integers of the appropriate size for the code below.
3692 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
3693 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
3694 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
3696 // Allow free casting and conversion of sizes as long as the sign doesn't
3698 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
3699 CastType FirstCast = getCastType(SrcTy, MidTy);
3700 CastType SecondCast = getCastType(MidTy, DstTy);
3702 // Capture the effect of these two casts. If the result is a legal cast,
3703 // the CastType is stored here, otherwise a special code is used.
3704 static const unsigned CastResult[] = {
3705 // First cast is noop
3707 // First cast is a truncate
3708 1, 1, 4, 4, // trunc->extend is not safe to eliminate
3709 // First cast is a sign ext
3710 2, 5, 2, 4, // signext->zeroext never ok
3711 // First cast is a zero ext
3715 unsigned Result = CastResult[FirstCast*4+SecondCast];
3717 default: assert(0 && "Illegal table value!");
3722 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
3723 // truncates, we could eliminate more casts.
3724 return (unsigned)getCastType(SrcTy, DstTy) == Result;
3726 return false; // Not possible to eliminate this here.
3728 // Sign or zero extend followed by truncate is always ok if the result
3729 // is a truncate or noop.
3730 CastType ResultCast = getCastType(SrcTy, DstTy);
3731 if (ResultCast == Noop || ResultCast == Truncate)
3733 // Otherwise we are still growing the value, we are only safe if the
3734 // result will match the sign/zeroextendness of the result.
3735 return ResultCast == FirstCast;
3741 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
3742 if (V->getType() == Ty || isa<Constant>(V)) return false;
3743 if (const CastInst *CI = dyn_cast<CastInst>(V))
3744 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
3750 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
3751 /// InsertBefore instruction. This is specialized a bit to avoid inserting
3752 /// casts that are known to not do anything...
3754 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
3755 Instruction *InsertBefore) {
3756 if (V->getType() == DestTy) return V;
3757 if (Constant *C = dyn_cast<Constant>(V))
3758 return ConstantExpr::getCast(C, DestTy);
3760 CastInst *CI = new CastInst(V, DestTy, V->getName());
3761 InsertNewInstBefore(CI, *InsertBefore);
3765 /// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
3766 /// try to eliminate the cast by moving the type information into the alloc.
3767 Instruction *InstCombiner::PromoteCastOfAllocation(CastInst &CI,
3768 AllocationInst &AI) {
3769 const PointerType *PTy = dyn_cast<PointerType>(CI.getType());
3770 if (AI.isArrayAllocation() || !PTy) return 0;
3772 // Remove any uses of AI that are dead.
3773 assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
3774 std::vector<Instruction*> DeadUsers;
3775 for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
3776 Instruction *User = cast<Instruction>(*UI++);
3777 if (isInstructionTriviallyDead(User)) {
3778 while (UI != E && *UI == User)
3779 ++UI; // If this instruction uses AI more than once, don't break UI.
3781 // Add operands to the worklist.
3782 AddUsesToWorkList(*User);
3784 DEBUG(std::cerr << "IC: DCE: " << *User);
3786 User->eraseFromParent();
3787 removeFromWorkList(User);
3791 // Finally, if the instruction now has one use, delete it.
3792 if (!AI.hasOneUse()) return 0;
3794 // Get the type really allocated and the type casted to.
3795 const Type *AllocElTy = AI.getAllocatedType();
3796 const Type *CastElTy = PTy->getElementType();
3797 if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
3799 uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
3800 uint64_t CastElTySize = TD->getTypeSize(CastElTy);
3802 // If the allocation is for an even multiple of the cast type size
3803 if (CastElTySize == 0 || AllocElTySize % CastElTySize != 0)
3805 Value *Amt = ConstantUInt::get(Type::UIntTy,
3806 AllocElTySize/CastElTySize);
3807 std::string Name = AI.getName(); AI.setName("");
3808 AllocationInst *New;
3809 if (isa<MallocInst>(AI))
3810 New = new MallocInst(CastElTy, Amt, Name);
3812 New = new AllocaInst(CastElTy, Amt, Name);
3813 InsertNewInstBefore(New, AI);
3814 return ReplaceInstUsesWith(CI, New);
3818 // CastInst simplification
3820 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
3821 Value *Src = CI.getOperand(0);
3823 // If the user is casting a value to the same type, eliminate this cast
3825 if (CI.getType() == Src->getType())
3826 return ReplaceInstUsesWith(CI, Src);
3828 if (isa<UndefValue>(Src)) // cast undef -> undef
3829 return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
3831 // If casting the result of another cast instruction, try to eliminate this
3834 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
3835 Value *A = CSrc->getOperand(0);
3836 if (isEliminableCastOfCast(A->getType(), CSrc->getType(),
3837 CI.getType(), TD)) {
3838 // This instruction now refers directly to the cast's src operand. This
3839 // has a good chance of making CSrc dead.
3840 CI.setOperand(0, CSrc->getOperand(0));
3844 // If this is an A->B->A cast, and we are dealing with integral types, try
3845 // to convert this into a logical 'and' instruction.
3847 if (A->getType()->isInteger() &&
3848 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
3849 CSrc->getType()->isUnsigned() && // B->A cast must zero extend
3850 CSrc->getType()->getPrimitiveSizeInBits() <
3851 CI.getType()->getPrimitiveSizeInBits()&&
3852 A->getType()->getPrimitiveSizeInBits() ==
3853 CI.getType()->getPrimitiveSizeInBits()) {
3854 assert(CSrc->getType() != Type::ULongTy &&
3855 "Cannot have type bigger than ulong!");
3856 uint64_t AndValue = ~0ULL>>(64-CSrc->getType()->getPrimitiveSizeInBits());
3857 Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(),
3859 AndOp = ConstantExpr::getCast(AndOp, A->getType());
3860 Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
3861 if (And->getType() != CI.getType()) {
3862 And->setName(CSrc->getName()+".mask");
3863 InsertNewInstBefore(And, CI);
3864 And = new CastInst(And, CI.getType());
3870 // If this is a cast to bool, turn it into the appropriate setne instruction.
3871 if (CI.getType() == Type::BoolTy)
3872 return BinaryOperator::createSetNE(CI.getOperand(0),
3873 Constant::getNullValue(CI.getOperand(0)->getType()));
3875 // If casting the result of a getelementptr instruction with no offset, turn
3876 // this into a cast of the original pointer!
3878 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
3879 bool AllZeroOperands = true;
3880 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
3881 if (!isa<Constant>(GEP->getOperand(i)) ||
3882 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
3883 AllZeroOperands = false;
3886 if (AllZeroOperands) {
3887 CI.setOperand(0, GEP->getOperand(0));
3892 // If we are casting a malloc or alloca to a pointer to a type of the same
3893 // size, rewrite the allocation instruction to allocate the "right" type.
3895 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
3896 if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
3899 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
3900 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
3902 if (isa<PHINode>(Src))
3903 if (Instruction *NV = FoldOpIntoPhi(CI))
3906 // If the source value is an instruction with only this use, we can attempt to
3907 // propagate the cast into the instruction. Also, only handle integral types
3909 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
3910 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
3911 CI.getType()->isInteger()) { // Don't mess with casts to bool here
3912 const Type *DestTy = CI.getType();
3913 unsigned SrcBitSize = Src->getType()->getPrimitiveSizeInBits();
3914 unsigned DestBitSize = DestTy->getPrimitiveSizeInBits();
3916 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
3917 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
3919 switch (SrcI->getOpcode()) {
3920 case Instruction::Add:
3921 case Instruction::Mul:
3922 case Instruction::And:
3923 case Instruction::Or:
3924 case Instruction::Xor:
3925 // If we are discarding information, or just changing the sign, rewrite.
3926 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
3927 // Don't insert two casts if they cannot be eliminated. We allow two
3928 // casts to be inserted if the sizes are the same. This could only be
3929 // converting signedness, which is a noop.
3930 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
3931 !ValueRequiresCast(Op0, DestTy, TD)) {
3932 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
3933 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
3934 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
3935 ->getOpcode(), Op0c, Op1c);
3939 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
3940 if (SrcBitSize == 1 && SrcI->getOpcode() == Instruction::Xor &&
3941 Op1 == ConstantBool::True &&
3942 (!Op0->hasOneUse() || !isa<SetCondInst>(Op0))) {
3943 Value *New = InsertOperandCastBefore(Op0, DestTy, &CI);
3944 return BinaryOperator::createXor(New,
3945 ConstantInt::get(CI.getType(), 1));
3948 case Instruction::Shl:
3949 // Allow changing the sign of the source operand. Do not allow changing
3950 // the size of the shift, UNLESS the shift amount is a constant. We
3951 // mush not change variable sized shifts to a smaller size, because it
3952 // is undefined to shift more bits out than exist in the value.
3953 if (DestBitSize == SrcBitSize ||
3954 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
3955 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
3956 return new ShiftInst(Instruction::Shl, Op0c, Op1);
3959 case Instruction::Shr:
3960 // If this is a signed shr, and if all bits shifted in are about to be
3961 // truncated off, turn it into an unsigned shr to allow greater
3963 if (DestBitSize < SrcBitSize && Src->getType()->isSigned() &&
3964 isa<ConstantInt>(Op1)) {
3965 unsigned ShiftAmt = cast<ConstantUInt>(Op1)->getValue();
3966 if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
3967 // Convert to unsigned.
3968 Value *N1 = InsertOperandCastBefore(Op0,
3969 Op0->getType()->getUnsignedVersion(), &CI);
3970 // Insert the new shift, which is now unsigned.
3971 N1 = InsertNewInstBefore(new ShiftInst(Instruction::Shr, N1,
3972 Op1, Src->getName()), CI);
3973 return new CastInst(N1, CI.getType());
3978 case Instruction::SetNE:
3979 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
3980 if (Op1C->getRawValue() == 0) {
3981 // If the input only has the low bit set, simplify directly.
3983 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
3984 // cast (X != 0) to int --> X if X&~1 == 0
3985 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
3986 if (CI.getType() == Op0->getType())
3987 return ReplaceInstUsesWith(CI, Op0);
3989 return new CastInst(Op0, CI.getType());
3992 // If the input is an and with a single bit, shift then simplify.
3993 ConstantInt *AndRHS;
3994 if (match(Op0, m_And(m_Value(), m_ConstantInt(AndRHS))))
3995 if (AndRHS->getRawValue() &&
3996 (AndRHS->getRawValue() & (AndRHS->getRawValue()-1)) == 0) {
3997 unsigned ShiftAmt = Log2_64(AndRHS->getRawValue());
3998 // Perform an unsigned shr by shiftamt. Convert input to
3999 // unsigned if it is signed.
4001 if (In->getType()->isSigned())
4002 In = InsertNewInstBefore(new CastInst(In,
4003 In->getType()->getUnsignedVersion(), In->getName()),CI);
4004 // Insert the shift to put the result in the low bit.
4005 In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In,
4006 ConstantInt::get(Type::UByteTy, ShiftAmt),
4007 In->getName()+".lobit"), CI);
4008 if (CI.getType() == In->getType())
4009 return ReplaceInstUsesWith(CI, In);
4011 return new CastInst(In, CI.getType());
4016 case Instruction::SetEQ:
4017 // We if we are just checking for a seteq of a single bit and casting it
4018 // to an integer. If so, shift the bit to the appropriate place then
4019 // cast to integer to avoid the comparison.
4020 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
4021 // Is Op1C a power of two or zero?
4022 if ((Op1C->getRawValue() & Op1C->getRawValue()-1) == 0) {
4023 // cast (X == 1) to int -> X iff X has only the low bit set.
4024 if (Op1C->getRawValue() == 1) {
4026 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
4027 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
4028 if (CI.getType() == Op0->getType())
4029 return ReplaceInstUsesWith(CI, Op0);
4031 return new CastInst(Op0, CI.getType());
4042 /// GetSelectFoldableOperands - We want to turn code that looks like this:
4044 /// %D = select %cond, %C, %A
4046 /// %C = select %cond, %B, 0
4049 /// Assuming that the specified instruction is an operand to the select, return
4050 /// a bitmask indicating which operands of this instruction are foldable if they
4051 /// equal the other incoming value of the select.
4053 static unsigned GetSelectFoldableOperands(Instruction *I) {
4054 switch (I->getOpcode()) {
4055 case Instruction::Add:
4056 case Instruction::Mul:
4057 case Instruction::And:
4058 case Instruction::Or:
4059 case Instruction::Xor:
4060 return 3; // Can fold through either operand.
4061 case Instruction::Sub: // Can only fold on the amount subtracted.
4062 case Instruction::Shl: // Can only fold on the shift amount.
4063 case Instruction::Shr:
4066 return 0; // Cannot fold
4070 /// GetSelectFoldableConstant - For the same transformation as the previous
4071 /// function, return the identity constant that goes into the select.
4072 static Constant *GetSelectFoldableConstant(Instruction *I) {
4073 switch (I->getOpcode()) {
4074 default: assert(0 && "This cannot happen!"); abort();
4075 case Instruction::Add:
4076 case Instruction::Sub:
4077 case Instruction::Or:
4078 case Instruction::Xor:
4079 return Constant::getNullValue(I->getType());
4080 case Instruction::Shl:
4081 case Instruction::Shr:
4082 return Constant::getNullValue(Type::UByteTy);
4083 case Instruction::And:
4084 return ConstantInt::getAllOnesValue(I->getType());
4085 case Instruction::Mul:
4086 return ConstantInt::get(I->getType(), 1);
4090 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
4091 /// have the same opcode and only one use each. Try to simplify this.
4092 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
4094 if (TI->getNumOperands() == 1) {
4095 // If this is a non-volatile load or a cast from the same type,
4097 if (TI->getOpcode() == Instruction::Cast) {
4098 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
4101 return 0; // unknown unary op.
4104 // Fold this by inserting a select from the input values.
4105 SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
4106 FI->getOperand(0), SI.getName()+".v");
4107 InsertNewInstBefore(NewSI, SI);
4108 return new CastInst(NewSI, TI->getType());
4111 // Only handle binary operators here.
4112 if (!isa<ShiftInst>(TI) && !isa<BinaryOperator>(TI))
4115 // Figure out if the operations have any operands in common.
4116 Value *MatchOp, *OtherOpT, *OtherOpF;
4118 if (TI->getOperand(0) == FI->getOperand(0)) {
4119 MatchOp = TI->getOperand(0);
4120 OtherOpT = TI->getOperand(1);
4121 OtherOpF = FI->getOperand(1);
4122 MatchIsOpZero = true;
4123 } else if (TI->getOperand(1) == FI->getOperand(1)) {
4124 MatchOp = TI->getOperand(1);
4125 OtherOpT = TI->getOperand(0);
4126 OtherOpF = FI->getOperand(0);
4127 MatchIsOpZero = false;
4128 } else if (!TI->isCommutative()) {
4130 } else if (TI->getOperand(0) == FI->getOperand(1)) {
4131 MatchOp = TI->getOperand(0);
4132 OtherOpT = TI->getOperand(1);
4133 OtherOpF = FI->getOperand(0);
4134 MatchIsOpZero = true;
4135 } else if (TI->getOperand(1) == FI->getOperand(0)) {
4136 MatchOp = TI->getOperand(1);
4137 OtherOpT = TI->getOperand(0);
4138 OtherOpF = FI->getOperand(1);
4139 MatchIsOpZero = true;
4144 // If we reach here, they do have operations in common.
4145 SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
4146 OtherOpF, SI.getName()+".v");
4147 InsertNewInstBefore(NewSI, SI);
4149 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
4151 return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
4153 return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
4156 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI);
4158 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp);
4162 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
4163 Value *CondVal = SI.getCondition();
4164 Value *TrueVal = SI.getTrueValue();
4165 Value *FalseVal = SI.getFalseValue();
4167 // select true, X, Y -> X
4168 // select false, X, Y -> Y
4169 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
4170 if (C == ConstantBool::True)
4171 return ReplaceInstUsesWith(SI, TrueVal);
4173 assert(C == ConstantBool::False);
4174 return ReplaceInstUsesWith(SI, FalseVal);
4177 // select C, X, X -> X
4178 if (TrueVal == FalseVal)
4179 return ReplaceInstUsesWith(SI, TrueVal);
4181 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
4182 return ReplaceInstUsesWith(SI, FalseVal);
4183 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
4184 return ReplaceInstUsesWith(SI, TrueVal);
4185 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
4186 if (isa<Constant>(TrueVal))
4187 return ReplaceInstUsesWith(SI, TrueVal);
4189 return ReplaceInstUsesWith(SI, FalseVal);
4192 if (SI.getType() == Type::BoolTy)
4193 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
4194 if (C == ConstantBool::True) {
4195 // Change: A = select B, true, C --> A = or B, C
4196 return BinaryOperator::createOr(CondVal, FalseVal);
4198 // Change: A = select B, false, C --> A = and !B, C
4200 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4201 "not."+CondVal->getName()), SI);
4202 return BinaryOperator::createAnd(NotCond, FalseVal);
4204 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
4205 if (C == ConstantBool::False) {
4206 // Change: A = select B, C, false --> A = and B, C
4207 return BinaryOperator::createAnd(CondVal, TrueVal);
4209 // Change: A = select B, C, true --> A = or !B, C
4211 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4212 "not."+CondVal->getName()), SI);
4213 return BinaryOperator::createOr(NotCond, TrueVal);
4217 // Selecting between two integer constants?
4218 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
4219 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
4220 // select C, 1, 0 -> cast C to int
4221 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
4222 return new CastInst(CondVal, SI.getType());
4223 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
4224 // select C, 0, 1 -> cast !C to int
4226 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4227 "not."+CondVal->getName()), SI);
4228 return new CastInst(NotCond, SI.getType());
4231 // If one of the constants is zero (we know they can't both be) and we
4232 // have a setcc instruction with zero, and we have an 'and' with the
4233 // non-constant value, eliminate this whole mess. This corresponds to
4234 // cases like this: ((X & 27) ? 27 : 0)
4235 if (TrueValC->isNullValue() || FalseValC->isNullValue())
4236 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
4237 if ((IC->getOpcode() == Instruction::SetEQ ||
4238 IC->getOpcode() == Instruction::SetNE) &&
4239 isa<ConstantInt>(IC->getOperand(1)) &&
4240 cast<Constant>(IC->getOperand(1))->isNullValue())
4241 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
4242 if (ICA->getOpcode() == Instruction::And &&
4243 isa<ConstantInt>(ICA->getOperand(1)) &&
4244 (ICA->getOperand(1) == TrueValC ||
4245 ICA->getOperand(1) == FalseValC) &&
4246 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
4247 // Okay, now we know that everything is set up, we just don't
4248 // know whether we have a setne or seteq and whether the true or
4249 // false val is the zero.
4250 bool ShouldNotVal = !TrueValC->isNullValue();
4251 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
4254 V = InsertNewInstBefore(BinaryOperator::create(
4255 Instruction::Xor, V, ICA->getOperand(1)), SI);
4256 return ReplaceInstUsesWith(SI, V);
4260 // See if we are selecting two values based on a comparison of the two values.
4261 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
4262 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
4263 // Transform (X == Y) ? X : Y -> Y
4264 if (SCI->getOpcode() == Instruction::SetEQ)
4265 return ReplaceInstUsesWith(SI, FalseVal);
4266 // Transform (X != Y) ? X : Y -> X
4267 if (SCI->getOpcode() == Instruction::SetNE)
4268 return ReplaceInstUsesWith(SI, TrueVal);
4269 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
4271 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
4272 // Transform (X == Y) ? Y : X -> X
4273 if (SCI->getOpcode() == Instruction::SetEQ)
4274 return ReplaceInstUsesWith(SI, FalseVal);
4275 // Transform (X != Y) ? Y : X -> Y
4276 if (SCI->getOpcode() == Instruction::SetNE)
4277 return ReplaceInstUsesWith(SI, TrueVal);
4278 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
4282 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
4283 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
4284 if (TI->hasOneUse() && FI->hasOneUse()) {
4285 bool isInverse = false;
4286 Instruction *AddOp = 0, *SubOp = 0;
4288 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
4289 if (TI->getOpcode() == FI->getOpcode())
4290 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
4293 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
4294 // even legal for FP.
4295 if (TI->getOpcode() == Instruction::Sub &&
4296 FI->getOpcode() == Instruction::Add) {
4297 AddOp = FI; SubOp = TI;
4298 } else if (FI->getOpcode() == Instruction::Sub &&
4299 TI->getOpcode() == Instruction::Add) {
4300 AddOp = TI; SubOp = FI;
4304 Value *OtherAddOp = 0;
4305 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
4306 OtherAddOp = AddOp->getOperand(1);
4307 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
4308 OtherAddOp = AddOp->getOperand(0);
4312 // So at this point we know we have:
4313 // select C, (add X, Y), (sub X, ?)
4314 // We can do the transform profitably if either 'Y' = '?' or '?' is
4316 if (SubOp->getOperand(1) == AddOp ||
4317 isa<Constant>(SubOp->getOperand(1))) {
4319 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
4320 NegVal = ConstantExpr::getNeg(C);
4322 NegVal = InsertNewInstBefore(
4323 BinaryOperator::createNeg(SubOp->getOperand(1)), SI);
4326 Value *NewTrueOp = OtherAddOp;
4327 Value *NewFalseOp = NegVal;
4329 std::swap(NewTrueOp, NewFalseOp);
4330 Instruction *NewSel =
4331 new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
4333 NewSel = InsertNewInstBefore(NewSel, SI);
4334 return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
4340 // See if we can fold the select into one of our operands.
4341 if (SI.getType()->isInteger()) {
4342 // See the comment above GetSelectFoldableOperands for a description of the
4343 // transformation we are doing here.
4344 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
4345 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
4346 !isa<Constant>(FalseVal))
4347 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
4348 unsigned OpToFold = 0;
4349 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
4351 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
4356 Constant *C = GetSelectFoldableConstant(TVI);
4357 std::string Name = TVI->getName(); TVI->setName("");
4358 Instruction *NewSel =
4359 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
4361 InsertNewInstBefore(NewSel, SI);
4362 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
4363 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
4364 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
4365 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
4367 assert(0 && "Unknown instruction!!");
4372 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
4373 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
4374 !isa<Constant>(TrueVal))
4375 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
4376 unsigned OpToFold = 0;
4377 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
4379 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
4384 Constant *C = GetSelectFoldableConstant(FVI);
4385 std::string Name = FVI->getName(); FVI->setName("");
4386 Instruction *NewSel =
4387 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
4389 InsertNewInstBefore(NewSel, SI);
4390 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
4391 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
4392 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
4393 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
4395 assert(0 && "Unknown instruction!!");
4401 if (BinaryOperator::isNot(CondVal)) {
4402 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
4403 SI.setOperand(1, FalseVal);
4404 SI.setOperand(2, TrueVal);
4412 // CallInst simplification
4414 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
4415 // Intrinsics cannot occur in an invoke, so handle them here instead of in
4417 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(&CI)) {
4418 bool Changed = false;
4420 // memmove/cpy/set of zero bytes is a noop.
4421 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
4422 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
4424 // FIXME: Increase alignment here.
4426 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
4427 if (CI->getRawValue() == 1) {
4428 // Replace the instruction with just byte operations. We would
4429 // transform other cases to loads/stores, but we don't know if
4430 // alignment is sufficient.
4434 // If we have a memmove and the source operation is a constant global,
4435 // then the source and dest pointers can't alias, so we can change this
4436 // into a call to memcpy.
4437 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI))
4438 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
4439 if (GVSrc->isConstant()) {
4440 Module *M = CI.getParent()->getParent()->getParent();
4441 Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
4442 CI.getCalledFunction()->getFunctionType());
4443 CI.setOperand(0, MemCpy);
4447 if (Changed) return &CI;
4448 } else if (DbgStopPointInst *SPI = dyn_cast<DbgStopPointInst>(&CI)) {
4449 // If this stoppoint is at the same source location as the previous
4450 // stoppoint in the chain, it is not needed.
4451 if (DbgStopPointInst *PrevSPI =
4452 dyn_cast<DbgStopPointInst>(SPI->getChain()))
4453 if (SPI->getLineNo() == PrevSPI->getLineNo() &&
4454 SPI->getColNo() == PrevSPI->getColNo()) {
4455 SPI->replaceAllUsesWith(PrevSPI);
4456 return EraseInstFromFunction(CI);
4460 return visitCallSite(&CI);
4463 // InvokeInst simplification
4465 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
4466 return visitCallSite(&II);
4469 // visitCallSite - Improvements for call and invoke instructions.
4471 Instruction *InstCombiner::visitCallSite(CallSite CS) {
4472 bool Changed = false;
4474 // If the callee is a constexpr cast of a function, attempt to move the cast
4475 // to the arguments of the call/invoke.
4476 if (transformConstExprCastCall(CS)) return 0;
4478 Value *Callee = CS.getCalledValue();
4480 if (Function *CalleeF = dyn_cast<Function>(Callee))
4481 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
4482 Instruction *OldCall = CS.getInstruction();
4483 // If the call and callee calling conventions don't match, this call must
4484 // be unreachable, as the call is undefined.
4485 new StoreInst(ConstantBool::True,
4486 UndefValue::get(PointerType::get(Type::BoolTy)), OldCall);
4487 if (!OldCall->use_empty())
4488 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
4489 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
4490 return EraseInstFromFunction(*OldCall);
4494 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
4495 // This instruction is not reachable, just remove it. We insert a store to
4496 // undef so that we know that this code is not reachable, despite the fact
4497 // that we can't modify the CFG here.
4498 new StoreInst(ConstantBool::True,
4499 UndefValue::get(PointerType::get(Type::BoolTy)),
4500 CS.getInstruction());
4502 if (!CS.getInstruction()->use_empty())
4503 CS.getInstruction()->
4504 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
4506 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
4507 // Don't break the CFG, insert a dummy cond branch.
4508 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
4509 ConstantBool::True, II);
4511 return EraseInstFromFunction(*CS.getInstruction());
4514 const PointerType *PTy = cast<PointerType>(Callee->getType());
4515 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
4516 if (FTy->isVarArg()) {
4517 // See if we can optimize any arguments passed through the varargs area of
4519 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
4520 E = CS.arg_end(); I != E; ++I)
4521 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
4522 // If this cast does not effect the value passed through the varargs
4523 // area, we can eliminate the use of the cast.
4524 Value *Op = CI->getOperand(0);
4525 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
4532 return Changed ? CS.getInstruction() : 0;
4535 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
4536 // attempt to move the cast to the arguments of the call/invoke.
4538 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
4539 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
4540 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
4541 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
4543 Function *Callee = cast<Function>(CE->getOperand(0));
4544 Instruction *Caller = CS.getInstruction();
4546 // Okay, this is a cast from a function to a different type. Unless doing so
4547 // would cause a type conversion of one of our arguments, change this call to
4548 // be a direct call with arguments casted to the appropriate types.
4550 const FunctionType *FT = Callee->getFunctionType();
4551 const Type *OldRetTy = Caller->getType();
4553 // Check to see if we are changing the return type...
4554 if (OldRetTy != FT->getReturnType()) {
4555 if (Callee->isExternal() &&
4556 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
4557 !Caller->use_empty())
4558 return false; // Cannot transform this return value...
4560 // If the callsite is an invoke instruction, and the return value is used by
4561 // a PHI node in a successor, we cannot change the return type of the call
4562 // because there is no place to put the cast instruction (without breaking
4563 // the critical edge). Bail out in this case.
4564 if (!Caller->use_empty())
4565 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
4566 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
4568 if (PHINode *PN = dyn_cast<PHINode>(*UI))
4569 if (PN->getParent() == II->getNormalDest() ||
4570 PN->getParent() == II->getUnwindDest())
4574 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
4575 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
4577 CallSite::arg_iterator AI = CS.arg_begin();
4578 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
4579 const Type *ParamTy = FT->getParamType(i);
4580 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
4581 if (Callee->isExternal() && !isConvertible) return false;
4584 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
4585 Callee->isExternal())
4586 return false; // Do not delete arguments unless we have a function body...
4588 // Okay, we decided that this is a safe thing to do: go ahead and start
4589 // inserting cast instructions as necessary...
4590 std::vector<Value*> Args;
4591 Args.reserve(NumActualArgs);
4593 AI = CS.arg_begin();
4594 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
4595 const Type *ParamTy = FT->getParamType(i);
4596 if ((*AI)->getType() == ParamTy) {
4597 Args.push_back(*AI);
4599 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
4604 // If the function takes more arguments than the call was taking, add them
4606 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
4607 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
4609 // If we are removing arguments to the function, emit an obnoxious warning...
4610 if (FT->getNumParams() < NumActualArgs)
4611 if (!FT->isVarArg()) {
4612 std::cerr << "WARNING: While resolving call to function '"
4613 << Callee->getName() << "' arguments were dropped!\n";
4615 // Add all of the arguments in their promoted form to the arg list...
4616 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
4617 const Type *PTy = getPromotedType((*AI)->getType());
4618 if (PTy != (*AI)->getType()) {
4619 // Must promote to pass through va_arg area!
4620 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
4621 InsertNewInstBefore(Cast, *Caller);
4622 Args.push_back(Cast);
4624 Args.push_back(*AI);
4629 if (FT->getReturnType() == Type::VoidTy)
4630 Caller->setName(""); // Void type should not have a name...
4633 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4634 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
4635 Args, Caller->getName(), Caller);
4636 cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
4638 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
4639 if (cast<CallInst>(Caller)->isTailCall())
4640 cast<CallInst>(NC)->setTailCall();
4641 cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
4644 // Insert a cast of the return type as necessary...
4646 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
4647 if (NV->getType() != Type::VoidTy) {
4648 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
4650 // If this is an invoke instruction, we should insert it after the first
4651 // non-phi, instruction in the normal successor block.
4652 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4653 BasicBlock::iterator I = II->getNormalDest()->begin();
4654 while (isa<PHINode>(I)) ++I;
4655 InsertNewInstBefore(NC, *I);
4657 // Otherwise, it's a call, just insert cast right after the call instr
4658 InsertNewInstBefore(NC, *Caller);
4660 AddUsersToWorkList(*Caller);
4662 NV = UndefValue::get(Caller->getType());
4666 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
4667 Caller->replaceAllUsesWith(NV);
4668 Caller->getParent()->getInstList().erase(Caller);
4669 removeFromWorkList(Caller);
4674 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
4675 // operator and they all are only used by the PHI, PHI together their
4676 // inputs, and do the operation once, to the result of the PHI.
4677 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
4678 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
4680 // Scan the instruction, looking for input operations that can be folded away.
4681 // If all input operands to the phi are the same instruction (e.g. a cast from
4682 // the same type or "+42") we can pull the operation through the PHI, reducing
4683 // code size and simplifying code.
4684 Constant *ConstantOp = 0;
4685 const Type *CastSrcTy = 0;
4686 if (isa<CastInst>(FirstInst)) {
4687 CastSrcTy = FirstInst->getOperand(0)->getType();
4688 } else if (isa<BinaryOperator>(FirstInst) || isa<ShiftInst>(FirstInst)) {
4689 // Can fold binop or shift if the RHS is a constant.
4690 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
4691 if (ConstantOp == 0) return 0;
4693 return 0; // Cannot fold this operation.
4696 // Check to see if all arguments are the same operation.
4697 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4698 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
4699 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
4700 if (!I->hasOneUse() || I->getOpcode() != FirstInst->getOpcode())
4703 if (I->getOperand(0)->getType() != CastSrcTy)
4704 return 0; // Cast operation must match.
4705 } else if (I->getOperand(1) != ConstantOp) {
4710 // Okay, they are all the same operation. Create a new PHI node of the
4711 // correct type, and PHI together all of the LHS's of the instructions.
4712 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
4713 PN.getName()+".in");
4714 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
4716 Value *InVal = FirstInst->getOperand(0);
4717 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
4719 // Add all operands to the new PHI.
4720 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4721 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
4722 if (NewInVal != InVal)
4724 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
4729 // The new PHI unions all of the same values together. This is really
4730 // common, so we handle it intelligently here for compile-time speed.
4734 InsertNewInstBefore(NewPN, PN);
4738 // Insert and return the new operation.
4739 if (isa<CastInst>(FirstInst))
4740 return new CastInst(PhiVal, PN.getType());
4741 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
4742 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
4744 return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(),
4745 PhiVal, ConstantOp);
4748 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
4750 static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &PotentiallyDeadPHIs) {
4751 if (PN->use_empty()) return true;
4752 if (!PN->hasOneUse()) return false;
4754 // Remember this node, and if we find the cycle, return.
4755 if (!PotentiallyDeadPHIs.insert(PN).second)
4758 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
4759 return DeadPHICycle(PU, PotentiallyDeadPHIs);
4764 // PHINode simplification
4766 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
4767 if (Value *V = PN.hasConstantValue())
4768 return ReplaceInstUsesWith(PN, V);
4770 // If the only user of this instruction is a cast instruction, and all of the
4771 // incoming values are constants, change this PHI to merge together the casted
4774 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
4775 if (CI->getType() != PN.getType()) { // noop casts will be folded
4776 bool AllConstant = true;
4777 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
4778 if (!isa<Constant>(PN.getIncomingValue(i))) {
4779 AllConstant = false;
4783 // Make a new PHI with all casted values.
4784 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
4785 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
4786 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
4787 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
4788 PN.getIncomingBlock(i));
4791 // Update the cast instruction.
4792 CI->setOperand(0, New);
4793 WorkList.push_back(CI); // revisit the cast instruction to fold.
4794 WorkList.push_back(New); // Make sure to revisit the new Phi
4795 return &PN; // PN is now dead!
4799 // If all PHI operands are the same operation, pull them through the PHI,
4800 // reducing code size.
4801 if (isa<Instruction>(PN.getIncomingValue(0)) &&
4802 PN.getIncomingValue(0)->hasOneUse())
4803 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
4806 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
4807 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
4808 // PHI)... break the cycle.
4810 if (PHINode *PU = dyn_cast<PHINode>(PN.use_back())) {
4811 std::set<PHINode*> PotentiallyDeadPHIs;
4812 PotentiallyDeadPHIs.insert(&PN);
4813 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
4814 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
4820 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
4821 Instruction *InsertPoint,
4823 unsigned PS = IC->getTargetData().getPointerSize();
4824 const Type *VTy = V->getType();
4825 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
4826 // We must insert a cast to ensure we sign-extend.
4827 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
4828 V->getName()), *InsertPoint);
4829 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
4834 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
4835 Value *PtrOp = GEP.getOperand(0);
4836 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
4837 // If so, eliminate the noop.
4838 if (GEP.getNumOperands() == 1)
4839 return ReplaceInstUsesWith(GEP, PtrOp);
4841 if (isa<UndefValue>(GEP.getOperand(0)))
4842 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
4844 bool HasZeroPointerIndex = false;
4845 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
4846 HasZeroPointerIndex = C->isNullValue();
4848 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
4849 return ReplaceInstUsesWith(GEP, PtrOp);
4851 // Eliminate unneeded casts for indices.
4852 bool MadeChange = false;
4853 gep_type_iterator GTI = gep_type_begin(GEP);
4854 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
4855 if (isa<SequentialType>(*GTI)) {
4856 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
4857 Value *Src = CI->getOperand(0);
4858 const Type *SrcTy = Src->getType();
4859 const Type *DestTy = CI->getType();
4860 if (Src->getType()->isInteger()) {
4861 if (SrcTy->getPrimitiveSizeInBits() ==
4862 DestTy->getPrimitiveSizeInBits()) {
4863 // We can always eliminate a cast from ulong or long to the other.
4864 // We can always eliminate a cast from uint to int or the other on
4865 // 32-bit pointer platforms.
4866 if (DestTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()){
4868 GEP.setOperand(i, Src);
4870 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
4871 SrcTy->getPrimitiveSize() == 4) {
4872 // We can always eliminate a cast from int to [u]long. We can
4873 // eliminate a cast from uint to [u]long iff the target is a 32-bit
4875 if (SrcTy->isSigned() ||
4876 SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
4878 GEP.setOperand(i, Src);
4883 // If we are using a wider index than needed for this platform, shrink it
4884 // to what we need. If the incoming value needs a cast instruction,
4885 // insert it. This explicit cast can make subsequent optimizations more
4887 Value *Op = GEP.getOperand(i);
4888 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
4889 if (Constant *C = dyn_cast<Constant>(Op)) {
4890 GEP.setOperand(i, ConstantExpr::getCast(C,
4891 TD->getIntPtrType()->getSignedVersion()));
4894 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
4895 Op->getName()), GEP);
4896 GEP.setOperand(i, Op);
4900 // If this is a constant idx, make sure to canonicalize it to be a signed
4901 // operand, otherwise CSE and other optimizations are pessimized.
4902 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
4903 GEP.setOperand(i, ConstantExpr::getCast(CUI,
4904 CUI->getType()->getSignedVersion()));
4908 if (MadeChange) return &GEP;
4910 // Combine Indices - If the source pointer to this getelementptr instruction
4911 // is a getelementptr instruction, combine the indices of the two
4912 // getelementptr instructions into a single instruction.
4914 std::vector<Value*> SrcGEPOperands;
4915 if (User *Src = dyn_castGetElementPtr(PtrOp))
4916 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
4918 if (!SrcGEPOperands.empty()) {
4919 // Note that if our source is a gep chain itself that we wait for that
4920 // chain to be resolved before we perform this transformation. This
4921 // avoids us creating a TON of code in some cases.
4923 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
4924 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
4925 return 0; // Wait until our source is folded to completion.
4927 std::vector<Value *> Indices;
4929 // Find out whether the last index in the source GEP is a sequential idx.
4930 bool EndsWithSequential = false;
4931 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
4932 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
4933 EndsWithSequential = !isa<StructType>(*I);
4935 // Can we combine the two pointer arithmetics offsets?
4936 if (EndsWithSequential) {
4937 // Replace: gep (gep %P, long B), long A, ...
4938 // With: T = long A+B; gep %P, T, ...
4940 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
4941 if (SO1 == Constant::getNullValue(SO1->getType())) {
4943 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
4946 // If they aren't the same type, convert both to an integer of the
4947 // target's pointer size.
4948 if (SO1->getType() != GO1->getType()) {
4949 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
4950 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
4951 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
4952 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
4954 unsigned PS = TD->getPointerSize();
4955 if (SO1->getType()->getPrimitiveSize() == PS) {
4956 // Convert GO1 to SO1's type.
4957 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
4959 } else if (GO1->getType()->getPrimitiveSize() == PS) {
4960 // Convert SO1 to GO1's type.
4961 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
4963 const Type *PT = TD->getIntPtrType();
4964 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
4965 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
4969 if (isa<Constant>(SO1) && isa<Constant>(GO1))
4970 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
4972 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
4973 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
4977 // Recycle the GEP we already have if possible.
4978 if (SrcGEPOperands.size() == 2) {
4979 GEP.setOperand(0, SrcGEPOperands[0]);
4980 GEP.setOperand(1, Sum);
4983 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
4984 SrcGEPOperands.end()-1);
4985 Indices.push_back(Sum);
4986 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
4988 } else if (isa<Constant>(*GEP.idx_begin()) &&
4989 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
4990 SrcGEPOperands.size() != 1) {
4991 // Otherwise we can do the fold if the first index of the GEP is a zero
4992 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
4993 SrcGEPOperands.end());
4994 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
4997 if (!Indices.empty())
4998 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
5000 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
5001 // GEP of global variable. If all of the indices for this GEP are
5002 // constants, we can promote this to a constexpr instead of an instruction.
5004 // Scan for nonconstants...
5005 std::vector<Constant*> Indices;
5006 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
5007 for (; I != E && isa<Constant>(*I); ++I)
5008 Indices.push_back(cast<Constant>(*I));
5010 if (I == E) { // If they are all constants...
5011 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
5013 // Replace all uses of the GEP with the new constexpr...
5014 return ReplaceInstUsesWith(GEP, CE);
5016 } else if (Value *X = isCast(PtrOp)) { // Is the operand a cast?
5017 if (!isa<PointerType>(X->getType())) {
5018 // Not interesting. Source pointer must be a cast from pointer.
5019 } else if (HasZeroPointerIndex) {
5020 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
5021 // into : GEP [10 x ubyte]* X, long 0, ...
5023 // This occurs when the program declares an array extern like "int X[];"
5025 const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
5026 const PointerType *XTy = cast<PointerType>(X->getType());
5027 if (const ArrayType *XATy =
5028 dyn_cast<ArrayType>(XTy->getElementType()))
5029 if (const ArrayType *CATy =
5030 dyn_cast<ArrayType>(CPTy->getElementType()))
5031 if (CATy->getElementType() == XATy->getElementType()) {
5032 // At this point, we know that the cast source type is a pointer
5033 // to an array of the same type as the destination pointer
5034 // array. Because the array type is never stepped over (there
5035 // is a leading zero) we can fold the cast into this GEP.
5036 GEP.setOperand(0, X);
5039 } else if (GEP.getNumOperands() == 2) {
5040 // Transform things like:
5041 // %t = getelementptr ubyte* cast ([2 x int]* %str to uint*), uint %V
5042 // into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast
5043 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
5044 const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
5045 if (isa<ArrayType>(SrcElTy) &&
5046 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
5047 TD->getTypeSize(ResElTy)) {
5048 Value *V = InsertNewInstBefore(
5049 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
5050 GEP.getOperand(1), GEP.getName()), GEP);
5051 return new CastInst(V, GEP.getType());
5054 // Transform things like:
5055 // getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp
5056 // (where tmp = 8*tmp2) into:
5057 // getelementptr [100 x double]* %arr, int 0, int %tmp.2
5059 if (isa<ArrayType>(SrcElTy) &&
5060 (ResElTy == Type::SByteTy || ResElTy == Type::UByteTy)) {
5061 uint64_t ArrayEltSize =
5062 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType());
5064 // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
5065 // allow either a mul, shift, or constant here.
5067 ConstantInt *Scale = 0;
5068 if (ArrayEltSize == 1) {
5069 NewIdx = GEP.getOperand(1);
5070 Scale = ConstantInt::get(NewIdx->getType(), 1);
5071 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
5072 NewIdx = ConstantInt::get(CI->getType(), 1);
5074 } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
5075 if (Inst->getOpcode() == Instruction::Shl &&
5076 isa<ConstantInt>(Inst->getOperand(1))) {
5077 unsigned ShAmt =cast<ConstantUInt>(Inst->getOperand(1))->getValue();
5078 if (Inst->getType()->isSigned())
5079 Scale = ConstantSInt::get(Inst->getType(), 1ULL << ShAmt);
5081 Scale = ConstantUInt::get(Inst->getType(), 1ULL << ShAmt);
5082 NewIdx = Inst->getOperand(0);
5083 } else if (Inst->getOpcode() == Instruction::Mul &&
5084 isa<ConstantInt>(Inst->getOperand(1))) {
5085 Scale = cast<ConstantInt>(Inst->getOperand(1));
5086 NewIdx = Inst->getOperand(0);
5090 // If the index will be to exactly the right offset with the scale taken
5091 // out, perform the transformation.
5092 if (Scale && Scale->getRawValue() % ArrayEltSize == 0) {
5093 if (ConstantSInt *C = dyn_cast<ConstantSInt>(Scale))
5094 Scale = ConstantSInt::get(C->getType(),
5095 (int64_t)C->getRawValue() /
5096 (int64_t)ArrayEltSize);
5098 Scale = ConstantUInt::get(Scale->getType(),
5099 Scale->getRawValue() / ArrayEltSize);
5100 if (Scale->getRawValue() != 1) {
5101 Constant *C = ConstantExpr::getCast(Scale, NewIdx->getType());
5102 Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale");
5103 NewIdx = InsertNewInstBefore(Sc, GEP);
5106 // Insert the new GEP instruction.
5108 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
5109 NewIdx, GEP.getName());
5110 Idx = InsertNewInstBefore(Idx, GEP);
5111 return new CastInst(Idx, GEP.getType());
5120 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
5121 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
5122 if (AI.isArrayAllocation()) // Check C != 1
5123 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
5124 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
5125 AllocationInst *New = 0;
5127 // Create and insert the replacement instruction...
5128 if (isa<MallocInst>(AI))
5129 New = new MallocInst(NewTy, 0, AI.getName());
5131 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
5132 New = new AllocaInst(NewTy, 0, AI.getName());
5135 InsertNewInstBefore(New, AI);
5137 // Scan to the end of the allocation instructions, to skip over a block of
5138 // allocas if possible...
5140 BasicBlock::iterator It = New;
5141 while (isa<AllocationInst>(*It)) ++It;
5143 // Now that I is pointing to the first non-allocation-inst in the block,
5144 // insert our getelementptr instruction...
5146 Value *NullIdx = Constant::getNullValue(Type::IntTy);
5147 Value *V = new GetElementPtrInst(New, NullIdx, NullIdx,
5148 New->getName()+".sub", It);
5150 // Now make everything use the getelementptr instead of the original
5152 return ReplaceInstUsesWith(AI, V);
5153 } else if (isa<UndefValue>(AI.getArraySize())) {
5154 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5157 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
5158 // Note that we only do this for alloca's, because malloc should allocate and
5159 // return a unique pointer, even for a zero byte allocation.
5160 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
5161 TD->getTypeSize(AI.getAllocatedType()) == 0)
5162 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5167 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
5168 Value *Op = FI.getOperand(0);
5170 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
5171 if (CastInst *CI = dyn_cast<CastInst>(Op))
5172 if (isa<PointerType>(CI->getOperand(0)->getType())) {
5173 FI.setOperand(0, CI->getOperand(0));
5177 // free undef -> unreachable.
5178 if (isa<UndefValue>(Op)) {
5179 // Insert a new store to null because we cannot modify the CFG here.
5180 new StoreInst(ConstantBool::True,
5181 UndefValue::get(PointerType::get(Type::BoolTy)), &FI);
5182 return EraseInstFromFunction(FI);
5185 // If we have 'free null' delete the instruction. This can happen in stl code
5186 // when lots of inlining happens.
5187 if (isa<ConstantPointerNull>(Op))
5188 return EraseInstFromFunction(FI);
5194 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
5195 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
5196 User *CI = cast<User>(LI.getOperand(0));
5197 Value *CastOp = CI->getOperand(0);
5199 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5200 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5201 const Type *SrcPTy = SrcTy->getElementType();
5203 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5204 // If the source is an array, the code below will not succeed. Check to
5205 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5207 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5208 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5209 if (ASrcTy->getNumElements() != 0) {
5210 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5211 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5212 SrcTy = cast<PointerType>(CastOp->getType());
5213 SrcPTy = SrcTy->getElementType();
5216 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5217 // Do not allow turning this into a load of an integer, which is then
5218 // casted to a pointer, this pessimizes pointer analysis a lot.
5219 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
5220 IC.getTargetData().getTypeSize(SrcPTy) ==
5221 IC.getTargetData().getTypeSize(DestPTy)) {
5223 // Okay, we are casting from one integer or pointer type to another of
5224 // the same size. Instead of casting the pointer before the load, cast
5225 // the result of the loaded value.
5226 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
5228 LI.isVolatile()),LI);
5229 // Now cast the result of the load.
5230 return new CastInst(NewLoad, LI.getType());
5237 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
5238 /// from this value cannot trap. If it is not obviously safe to load from the
5239 /// specified pointer, we do a quick local scan of the basic block containing
5240 /// ScanFrom, to determine if the address is already accessed.
5241 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
5242 // If it is an alloca or global variable, it is always safe to load from.
5243 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
5245 // Otherwise, be a little bit agressive by scanning the local block where we
5246 // want to check to see if the pointer is already being loaded or stored
5247 // from/to. If so, the previous load or store would have already trapped,
5248 // so there is no harm doing an extra load (also, CSE will later eliminate
5249 // the load entirely).
5250 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
5255 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
5256 if (LI->getOperand(0) == V) return true;
5257 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
5258 if (SI->getOperand(1) == V) return true;
5264 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
5265 Value *Op = LI.getOperand(0);
5267 // load (cast X) --> cast (load X) iff safe
5268 if (CastInst *CI = dyn_cast<CastInst>(Op))
5269 if (Instruction *Res = InstCombineLoadCast(*this, LI))
5272 // None of the following transforms are legal for volatile loads.
5273 if (LI.isVolatile()) return 0;
5275 if (&LI.getParent()->front() != &LI) {
5276 BasicBlock::iterator BBI = &LI; --BBI;
5277 // If the instruction immediately before this is a store to the same
5278 // address, do a simple form of store->load forwarding.
5279 if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
5280 if (SI->getOperand(1) == LI.getOperand(0))
5281 return ReplaceInstUsesWith(LI, SI->getOperand(0));
5282 if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
5283 if (LIB->getOperand(0) == LI.getOperand(0))
5284 return ReplaceInstUsesWith(LI, LIB);
5287 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
5288 if (isa<ConstantPointerNull>(GEPI->getOperand(0)) ||
5289 isa<UndefValue>(GEPI->getOperand(0))) {
5290 // Insert a new store to null instruction before the load to indicate
5291 // that this code is not reachable. We do this instead of inserting
5292 // an unreachable instruction directly because we cannot modify the
5294 new StoreInst(UndefValue::get(LI.getType()),
5295 Constant::getNullValue(Op->getType()), &LI);
5296 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5299 if (Constant *C = dyn_cast<Constant>(Op)) {
5300 // load null/undef -> undef
5301 if ((C->isNullValue() || isa<UndefValue>(C))) {
5302 // Insert a new store to null instruction before the load to indicate that
5303 // this code is not reachable. We do this instead of inserting an
5304 // unreachable instruction directly because we cannot modify the CFG.
5305 new StoreInst(UndefValue::get(LI.getType()),
5306 Constant::getNullValue(Op->getType()), &LI);
5307 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5310 // Instcombine load (constant global) into the value loaded.
5311 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
5312 if (GV->isConstant() && !GV->isExternal())
5313 return ReplaceInstUsesWith(LI, GV->getInitializer());
5315 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
5316 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
5317 if (CE->getOpcode() == Instruction::GetElementPtr) {
5318 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
5319 if (GV->isConstant() && !GV->isExternal())
5321 ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
5322 return ReplaceInstUsesWith(LI, V);
5323 if (CE->getOperand(0)->isNullValue()) {
5324 // Insert a new store to null instruction before the load to indicate
5325 // that this code is not reachable. We do this instead of inserting
5326 // an unreachable instruction directly because we cannot modify the
5328 new StoreInst(UndefValue::get(LI.getType()),
5329 Constant::getNullValue(Op->getType()), &LI);
5330 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5333 } else if (CE->getOpcode() == Instruction::Cast) {
5334 if (Instruction *Res = InstCombineLoadCast(*this, LI))
5339 if (Op->hasOneUse()) {
5340 // Change select and PHI nodes to select values instead of addresses: this
5341 // helps alias analysis out a lot, allows many others simplifications, and
5342 // exposes redundancy in the code.
5344 // Note that we cannot do the transformation unless we know that the
5345 // introduced loads cannot trap! Something like this is valid as long as
5346 // the condition is always false: load (select bool %C, int* null, int* %G),
5347 // but it would not be valid if we transformed it to load from null
5350 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
5351 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
5352 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
5353 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
5354 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
5355 SI->getOperand(1)->getName()+".val"), LI);
5356 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
5357 SI->getOperand(2)->getName()+".val"), LI);
5358 return new SelectInst(SI->getCondition(), V1, V2);
5361 // load (select (cond, null, P)) -> load P
5362 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
5363 if (C->isNullValue()) {
5364 LI.setOperand(0, SI->getOperand(2));
5368 // load (select (cond, P, null)) -> load P
5369 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
5370 if (C->isNullValue()) {
5371 LI.setOperand(0, SI->getOperand(1));
5375 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
5376 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
5377 bool Safe = PN->getParent() == LI.getParent();
5379 // Scan all of the instructions between the PHI and the load to make
5380 // sure there are no instructions that might possibly alter the value
5381 // loaded from the PHI.
5383 BasicBlock::iterator I = &LI;
5384 for (--I; !isa<PHINode>(I); --I)
5385 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
5391 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
5392 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
5393 PN->getIncomingBlock(i)->getTerminator()))
5398 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
5399 InsertNewInstBefore(NewPN, *PN);
5400 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
5402 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
5403 BasicBlock *BB = PN->getIncomingBlock(i);
5404 Value *&TheLoad = LoadMap[BB];
5406 Value *InVal = PN->getIncomingValue(i);
5407 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
5408 InVal->getName()+".val"),
5409 *BB->getTerminator());
5411 NewPN->addIncoming(TheLoad, BB);
5413 return ReplaceInstUsesWith(LI, NewPN);
5420 /// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store (cast V), P'
5422 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
5423 User *CI = cast<User>(SI.getOperand(1));
5424 Value *CastOp = CI->getOperand(0);
5426 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5427 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5428 const Type *SrcPTy = SrcTy->getElementType();
5430 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5431 // If the source is an array, the code below will not succeed. Check to
5432 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5434 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5435 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5436 if (ASrcTy->getNumElements() != 0) {
5437 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5438 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5439 SrcTy = cast<PointerType>(CastOp->getType());
5440 SrcPTy = SrcTy->getElementType();
5443 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5444 IC.getTargetData().getTypeSize(SrcPTy) ==
5445 IC.getTargetData().getTypeSize(DestPTy)) {
5447 // Okay, we are casting from one integer or pointer type to another of
5448 // the same size. Instead of casting the pointer before the store, cast
5449 // the value to be stored.
5451 if (Constant *C = dyn_cast<Constant>(SI.getOperand(0)))
5452 NewCast = ConstantExpr::getCast(C, SrcPTy);
5454 NewCast = IC.InsertNewInstBefore(new CastInst(SI.getOperand(0),
5456 SI.getOperand(0)->getName()+".c"), SI);
5458 return new StoreInst(NewCast, CastOp);
5465 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
5466 Value *Val = SI.getOperand(0);
5467 Value *Ptr = SI.getOperand(1);
5469 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
5470 removeFromWorkList(&SI);
5471 SI.eraseFromParent();
5476 if (SI.isVolatile()) return 0; // Don't hack volatile loads.
5478 // store X, null -> turns into 'unreachable' in SimplifyCFG
5479 if (isa<ConstantPointerNull>(Ptr)) {
5480 if (!isa<UndefValue>(Val)) {
5481 SI.setOperand(0, UndefValue::get(Val->getType()));
5482 if (Instruction *U = dyn_cast<Instruction>(Val))
5483 WorkList.push_back(U); // Dropped a use.
5486 return 0; // Do not modify these!
5489 // store undef, Ptr -> noop
5490 if (isa<UndefValue>(Val)) {
5491 removeFromWorkList(&SI);
5492 SI.eraseFromParent();
5497 // If the pointer destination is a cast, see if we can fold the cast into the
5499 if (CastInst *CI = dyn_cast<CastInst>(Ptr))
5500 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5502 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
5503 if (CE->getOpcode() == Instruction::Cast)
5504 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5508 // If this store is the last instruction in the basic block, and if the block
5509 // ends with an unconditional branch, try to move it to the successor block.
5510 BasicBlock::iterator BBI = &SI; ++BBI;
5511 if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
5512 if (BI->isUnconditional()) {
5513 // Check to see if the successor block has exactly two incoming edges. If
5514 // so, see if the other predecessor contains a store to the same location.
5515 // if so, insert a PHI node (if needed) and move the stores down.
5516 BasicBlock *Dest = BI->getSuccessor(0);
5518 pred_iterator PI = pred_begin(Dest);
5519 BasicBlock *Other = 0;
5520 if (*PI != BI->getParent())
5523 if (PI != pred_end(Dest)) {
5524 if (*PI != BI->getParent())
5529 if (++PI != pred_end(Dest))
5532 if (Other) { // If only one other pred...
5533 BBI = Other->getTerminator();
5534 // Make sure this other block ends in an unconditional branch and that
5535 // there is an instruction before the branch.
5536 if (isa<BranchInst>(BBI) && cast<BranchInst>(BBI)->isUnconditional() &&
5537 BBI != Other->begin()) {
5539 StoreInst *OtherStore = dyn_cast<StoreInst>(BBI);
5541 // If this instruction is a store to the same location.
5542 if (OtherStore && OtherStore->getOperand(1) == SI.getOperand(1)) {
5543 // Okay, we know we can perform this transformation. Insert a PHI
5544 // node now if we need it.
5545 Value *MergedVal = OtherStore->getOperand(0);
5546 if (MergedVal != SI.getOperand(0)) {
5547 PHINode *PN = new PHINode(MergedVal->getType(), "storemerge");
5548 PN->reserveOperandSpace(2);
5549 PN->addIncoming(SI.getOperand(0), SI.getParent());
5550 PN->addIncoming(OtherStore->getOperand(0), Other);
5551 MergedVal = InsertNewInstBefore(PN, Dest->front());
5554 // Advance to a place where it is safe to insert the new store and
5556 BBI = Dest->begin();
5557 while (isa<PHINode>(BBI)) ++BBI;
5558 InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
5559 OtherStore->isVolatile()), *BBI);
5561 // Nuke the old stores.
5562 removeFromWorkList(&SI);
5563 removeFromWorkList(OtherStore);
5564 SI.eraseFromParent();
5565 OtherStore->eraseFromParent();
5577 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
5578 // Change br (not X), label True, label False to: br X, label False, True
5580 BasicBlock *TrueDest;
5581 BasicBlock *FalseDest;
5582 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
5583 !isa<Constant>(X)) {
5584 // Swap Destinations and condition...
5586 BI.setSuccessor(0, FalseDest);
5587 BI.setSuccessor(1, TrueDest);
5591 // Cannonicalize setne -> seteq
5592 Instruction::BinaryOps Op; Value *Y;
5593 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
5594 TrueDest, FalseDest)))
5595 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
5596 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
5597 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
5598 std::string Name = I->getName(); I->setName("");
5599 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
5600 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
5601 // Swap Destinations and condition...
5602 BI.setCondition(NewSCC);
5603 BI.setSuccessor(0, FalseDest);
5604 BI.setSuccessor(1, TrueDest);
5605 removeFromWorkList(I);
5606 I->getParent()->getInstList().erase(I);
5607 WorkList.push_back(cast<Instruction>(NewSCC));
5614 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
5615 Value *Cond = SI.getCondition();
5616 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
5617 if (I->getOpcode() == Instruction::Add)
5618 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
5619 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
5620 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
5621 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
5623 SI.setOperand(0, I->getOperand(0));
5624 WorkList.push_back(I);
5631 void InstCombiner::removeFromWorkList(Instruction *I) {
5632 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
5637 /// TryToSinkInstruction - Try to move the specified instruction from its
5638 /// current block into the beginning of DestBlock, which can only happen if it's
5639 /// safe to move the instruction past all of the instructions between it and the
5640 /// end of its block.
5641 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
5642 assert(I->hasOneUse() && "Invariants didn't hold!");
5644 // Cannot move control-flow-involving instructions.
5645 if (isa<PHINode>(I) || isa<InvokeInst>(I) || isa<CallInst>(I)) return false;
5647 // Do not sink alloca instructions out of the entry block.
5648 if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front())
5651 // We can only sink load instructions if there is nothing between the load and
5652 // the end of block that could change the value.
5653 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
5654 if (LI->isVolatile()) return false; // Don't sink volatile loads.
5656 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
5658 if (Scan->mayWriteToMemory())
5662 BasicBlock::iterator InsertPos = DestBlock->begin();
5663 while (isa<PHINode>(InsertPos)) ++InsertPos;
5665 I->moveBefore(InsertPos);
5670 bool InstCombiner::runOnFunction(Function &F) {
5671 bool Changed = false;
5672 TD = &getAnalysis<TargetData>();
5675 // Populate the worklist with the reachable instructions.
5676 std::set<BasicBlock*> Visited;
5677 for (df_ext_iterator<BasicBlock*> BB = df_ext_begin(&F.front(), Visited),
5678 E = df_ext_end(&F.front(), Visited); BB != E; ++BB)
5679 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
5680 WorkList.push_back(I);
5682 // Do a quick scan over the function. If we find any blocks that are
5683 // unreachable, remove any instructions inside of them. This prevents
5684 // the instcombine code from having to deal with some bad special cases.
5685 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
5686 if (!Visited.count(BB)) {
5687 Instruction *Term = BB->getTerminator();
5688 while (Term != BB->begin()) { // Remove instrs bottom-up
5689 BasicBlock::iterator I = Term; --I;
5691 DEBUG(std::cerr << "IC: DCE: " << *I);
5694 if (!I->use_empty())
5695 I->replaceAllUsesWith(UndefValue::get(I->getType()));
5696 I->eraseFromParent();
5701 while (!WorkList.empty()) {
5702 Instruction *I = WorkList.back(); // Get an instruction from the worklist
5703 WorkList.pop_back();
5705 // Check to see if we can DCE or ConstantPropagate the instruction...
5706 // Check to see if we can DIE the instruction...
5707 if (isInstructionTriviallyDead(I)) {
5708 // Add operands to the worklist...
5709 if (I->getNumOperands() < 4)
5710 AddUsesToWorkList(*I);
5713 DEBUG(std::cerr << "IC: DCE: " << *I);
5715 I->eraseFromParent();
5716 removeFromWorkList(I);
5720 // Instruction isn't dead, see if we can constant propagate it...
5721 if (Constant *C = ConstantFoldInstruction(I)) {
5722 Value* Ptr = I->getOperand(0);
5723 if (isa<GetElementPtrInst>(I) &&
5724 cast<Constant>(Ptr)->isNullValue() &&
5725 !isa<ConstantPointerNull>(C) &&
5726 cast<PointerType>(Ptr->getType())->getElementType()->isSized()) {
5727 // If this is a constant expr gep that is effectively computing an
5728 // "offsetof", fold it into 'cast int X to T*' instead of 'gep 0, 0, 12'
5729 bool isFoldableGEP = true;
5730 for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
5731 if (!isa<ConstantInt>(I->getOperand(i)))
5732 isFoldableGEP = false;
5733 if (isFoldableGEP) {
5734 uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
5735 std::vector<Value*>(I->op_begin()+1, I->op_end()));
5736 C = ConstantUInt::get(Type::ULongTy, Offset);
5737 C = ConstantExpr::getCast(C, TD->getIntPtrType());
5738 C = ConstantExpr::getCast(C, I->getType());
5742 DEBUG(std::cerr << "IC: ConstFold to: " << *C << " from: " << *I);
5744 // Add operands to the worklist...
5745 AddUsesToWorkList(*I);
5746 ReplaceInstUsesWith(*I, C);
5749 I->getParent()->getInstList().erase(I);
5750 removeFromWorkList(I);
5754 // See if we can trivially sink this instruction to a successor basic block.
5755 if (I->hasOneUse()) {
5756 BasicBlock *BB = I->getParent();
5757 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
5758 if (UserParent != BB) {
5759 bool UserIsSuccessor = false;
5760 // See if the user is one of our successors.
5761 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
5762 if (*SI == UserParent) {
5763 UserIsSuccessor = true;
5767 // If the user is one of our immediate successors, and if that successor
5768 // only has us as a predecessors (we'd have to split the critical edge
5769 // otherwise), we can keep going.
5770 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
5771 next(pred_begin(UserParent)) == pred_end(UserParent))
5772 // Okay, the CFG is simple enough, try to sink this instruction.
5773 Changed |= TryToSinkInstruction(I, UserParent);
5777 // Now that we have an instruction, try combining it to simplify it...
5778 if (Instruction *Result = visit(*I)) {
5780 // Should we replace the old instruction with a new one?
5782 DEBUG(std::cerr << "IC: Old = " << *I
5783 << " New = " << *Result);
5785 // Everything uses the new instruction now.
5786 I->replaceAllUsesWith(Result);
5788 // Push the new instruction and any users onto the worklist.
5789 WorkList.push_back(Result);
5790 AddUsersToWorkList(*Result);
5792 // Move the name to the new instruction first...
5793 std::string OldName = I->getName(); I->setName("");
5794 Result->setName(OldName);
5796 // Insert the new instruction into the basic block...
5797 BasicBlock *InstParent = I->getParent();
5798 BasicBlock::iterator InsertPos = I;
5800 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
5801 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
5804 InstParent->getInstList().insert(InsertPos, Result);
5806 // Make sure that we reprocess all operands now that we reduced their
5808 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
5809 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
5810 WorkList.push_back(OpI);
5812 // Instructions can end up on the worklist more than once. Make sure
5813 // we do not process an instruction that has been deleted.
5814 removeFromWorkList(I);
5816 // Erase the old instruction.
5817 InstParent->getInstList().erase(I);
5819 DEBUG(std::cerr << "IC: MOD = " << *I);
5821 // If the instruction was modified, it's possible that it is now dead.
5822 // if so, remove it.
5823 if (isInstructionTriviallyDead(I)) {
5824 // Make sure we process all operands now that we are reducing their
5826 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
5827 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
5828 WorkList.push_back(OpI);
5830 // Instructions may end up in the worklist more than once. Erase all
5831 // occurrances of this instruction.
5832 removeFromWorkList(I);
5833 I->eraseFromParent();
5835 WorkList.push_back(Result);
5836 AddUsersToWorkList(*Result);
5846 FunctionPass *llvm::createInstructionCombiningPass() {
5847 return new InstCombiner();