1 //===- InstructionCombining.cpp - Combine multiple instructions -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // InstructionCombining - Combine instructions to form fewer, simple
11 // instructions. This pass does not modify the CFG This pass is where algebraic
12 // simplification happens.
14 // This pass combines things like:
20 // This is a simple worklist driven algorithm.
22 // This pass guarantees that the following canonicalizations are performed on
24 // 1. If a binary operator has a constant operand, it is moved to the RHS
25 // 2. Bitwise operators with constant operands are always grouped so that
26 // shifts are performed first, then or's, then and's, then xor's.
27 // 3. SetCC instructions are converted from <,>,<=,>= to ==,!= if possible
28 // 4. All SetCC instructions on boolean values are replaced with logical ops
29 // 5. add X, X is represented as (X*2) => (X << 1)
30 // 6. Multiplies with a power-of-two constant argument are transformed into
34 //===----------------------------------------------------------------------===//
36 #define DEBUG_TYPE "instcombine"
37 #include "llvm/Transforms/Scalar.h"
38 #include "llvm/IntrinsicInst.h"
39 #include "llvm/Pass.h"
40 #include "llvm/DerivedTypes.h"
41 #include "llvm/GlobalVariable.h"
42 #include "llvm/Target/TargetData.h"
43 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
44 #include "llvm/Transforms/Utils/Local.h"
45 #include "llvm/Support/CallSite.h"
46 #include "llvm/Support/Debug.h"
47 #include "llvm/Support/GetElementPtrTypeIterator.h"
48 #include "llvm/Support/InstVisitor.h"
49 #include "llvm/Support/MathExtras.h"
50 #include "llvm/Support/PatternMatch.h"
51 #include "llvm/ADT/DepthFirstIterator.h"
52 #include "llvm/ADT/Statistic.h"
53 #include "llvm/ADT/STLExtras.h"
57 using namespace llvm::PatternMatch;
60 Statistic<> NumCombined ("instcombine", "Number of insts combined");
61 Statistic<> NumConstProp("instcombine", "Number of constant folds");
62 Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
63 Statistic<> NumSunkInst ("instcombine", "Number of instructions sunk");
65 class InstCombiner : public FunctionPass,
66 public InstVisitor<InstCombiner, Instruction*> {
67 // Worklist of all of the instructions that need to be simplified.
68 std::vector<Instruction*> WorkList;
71 /// AddUsersToWorkList - When an instruction is simplified, add all users of
72 /// the instruction to the work lists because they might get more simplified
75 void AddUsersToWorkList(Instruction &I) {
76 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
78 WorkList.push_back(cast<Instruction>(*UI));
81 /// AddUsesToWorkList - When an instruction is simplified, add operands to
82 /// the work lists because they might get more simplified now.
84 void AddUsesToWorkList(Instruction &I) {
85 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
86 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
87 WorkList.push_back(Op);
90 // removeFromWorkList - remove all instances of I from the worklist.
91 void removeFromWorkList(Instruction *I);
93 virtual bool runOnFunction(Function &F);
95 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
96 AU.addRequired<TargetData>();
100 TargetData &getTargetData() const { return *TD; }
102 // Visitation implementation - Implement instruction combining for different
103 // instruction types. The semantics are as follows:
105 // null - No change was made
106 // I - Change was made, I is still valid, I may be dead though
107 // otherwise - Change was made, replace I with returned instruction
109 Instruction *visitAdd(BinaryOperator &I);
110 Instruction *visitSub(BinaryOperator &I);
111 Instruction *visitMul(BinaryOperator &I);
112 Instruction *visitDiv(BinaryOperator &I);
113 Instruction *visitRem(BinaryOperator &I);
114 Instruction *visitAnd(BinaryOperator &I);
115 Instruction *visitOr (BinaryOperator &I);
116 Instruction *visitXor(BinaryOperator &I);
117 Instruction *visitSetCondInst(SetCondInst &I);
118 Instruction *visitSetCondInstWithCastAndCast(SetCondInst &SCI);
120 Instruction *FoldGEPSetCC(User *GEPLHS, Value *RHS,
121 Instruction::BinaryOps Cond, Instruction &I);
122 Instruction *visitShiftInst(ShiftInst &I);
123 Instruction *FoldShiftByConstant(Value *Op0, ConstantUInt *Op1,
125 Instruction *visitCastInst(CastInst &CI);
126 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
128 Instruction *visitSelectInst(SelectInst &CI);
129 Instruction *visitCallInst(CallInst &CI);
130 Instruction *visitInvokeInst(InvokeInst &II);
131 Instruction *visitPHINode(PHINode &PN);
132 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
133 Instruction *visitAllocationInst(AllocationInst &AI);
134 Instruction *visitFreeInst(FreeInst &FI);
135 Instruction *visitLoadInst(LoadInst &LI);
136 Instruction *visitStoreInst(StoreInst &SI);
137 Instruction *visitBranchInst(BranchInst &BI);
138 Instruction *visitSwitchInst(SwitchInst &SI);
139 Instruction *visitExtractElementInst(ExtractElementInst &EI);
141 // visitInstruction - Specify what to return for unhandled instructions...
142 Instruction *visitInstruction(Instruction &I) { return 0; }
145 Instruction *visitCallSite(CallSite CS);
146 bool transformConstExprCastCall(CallSite CS);
149 // InsertNewInstBefore - insert an instruction New before instruction Old
150 // in the program. Add the new instruction to the worklist.
152 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
153 assert(New && New->getParent() == 0 &&
154 "New instruction already inserted into a basic block!");
155 BasicBlock *BB = Old.getParent();
156 BB->getInstList().insert(&Old, New); // Insert inst
157 WorkList.push_back(New); // Add to worklist
161 /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
162 /// This also adds the cast to the worklist. Finally, this returns the
164 Value *InsertCastBefore(Value *V, const Type *Ty, Instruction &Pos) {
165 if (V->getType() == Ty) return V;
167 Instruction *C = new CastInst(V, Ty, V->getName(), &Pos);
168 WorkList.push_back(C);
172 // ReplaceInstUsesWith - This method is to be used when an instruction is
173 // found to be dead, replacable with another preexisting expression. Here
174 // we add all uses of I to the worklist, replace all uses of I with the new
175 // value, then return I, so that the inst combiner will know that I was
178 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
179 AddUsersToWorkList(I); // Add all modified instrs to worklist
181 I.replaceAllUsesWith(V);
184 // If we are replacing the instruction with itself, this must be in a
185 // segment of unreachable code, so just clobber the instruction.
186 I.replaceAllUsesWith(UndefValue::get(I.getType()));
191 // EraseInstFromFunction - When dealing with an instruction that has side
192 // effects or produces a void value, we can't rely on DCE to delete the
193 // instruction. Instead, visit methods should return the value returned by
195 Instruction *EraseInstFromFunction(Instruction &I) {
196 assert(I.use_empty() && "Cannot erase instruction that is used!");
197 AddUsesToWorkList(I);
198 removeFromWorkList(&I);
200 return 0; // Don't do anything with FI
205 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
206 /// InsertBefore instruction. This is specialized a bit to avoid inserting
207 /// casts that are known to not do anything...
209 Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
210 Instruction *InsertBefore);
212 // SimplifyCommutative - This performs a few simplifications for commutative
214 bool SimplifyCommutative(BinaryOperator &I);
217 // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
218 // PHI node as operand #0, see if we can fold the instruction into the PHI
219 // (which is only possible if all operands to the PHI are constants).
220 Instruction *FoldOpIntoPhi(Instruction &I);
222 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
223 // operator and they all are only used by the PHI, PHI together their
224 // inputs, and do the operation once, to the result of the PHI.
225 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
227 Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
228 ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
230 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantIntegral *Mask,
231 bool isSub, Instruction &I);
232 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
233 bool Inside, Instruction &IB);
234 Instruction *PromoteCastOfAllocation(CastInst &CI, AllocationInst &AI);
237 RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
240 // getComplexity: Assign a complexity or rank value to LLVM Values...
241 // 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
242 static unsigned getComplexity(Value *V) {
243 if (isa<Instruction>(V)) {
244 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
248 if (isa<Argument>(V)) return 3;
249 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
252 // isOnlyUse - Return true if this instruction will be deleted if we stop using
254 static bool isOnlyUse(Value *V) {
255 return V->hasOneUse() || isa<Constant>(V);
258 // getPromotedType - Return the specified type promoted as it would be to pass
259 // though a va_arg area...
260 static const Type *getPromotedType(const Type *Ty) {
261 switch (Ty->getTypeID()) {
262 case Type::SByteTyID:
263 case Type::ShortTyID: return Type::IntTy;
264 case Type::UByteTyID:
265 case Type::UShortTyID: return Type::UIntTy;
266 case Type::FloatTyID: return Type::DoubleTy;
271 /// isCast - If the specified operand is a CastInst or a constant expr cast,
272 /// return the operand value, otherwise return null.
273 static Value *isCast(Value *V) {
274 if (CastInst *I = dyn_cast<CastInst>(V))
275 return I->getOperand(0);
276 else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
277 if (CE->getOpcode() == Instruction::Cast)
278 return CE->getOperand(0);
282 // SimplifyCommutative - This performs a few simplifications for commutative
285 // 1. Order operands such that they are listed from right (least complex) to
286 // left (most complex). This puts constants before unary operators before
289 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
290 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
292 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
293 bool Changed = false;
294 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
295 Changed = !I.swapOperands();
297 if (!I.isAssociative()) return Changed;
298 Instruction::BinaryOps Opcode = I.getOpcode();
299 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
300 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
301 if (isa<Constant>(I.getOperand(1))) {
302 Constant *Folded = ConstantExpr::get(I.getOpcode(),
303 cast<Constant>(I.getOperand(1)),
304 cast<Constant>(Op->getOperand(1)));
305 I.setOperand(0, Op->getOperand(0));
306 I.setOperand(1, Folded);
308 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
309 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
310 isOnlyUse(Op) && isOnlyUse(Op1)) {
311 Constant *C1 = cast<Constant>(Op->getOperand(1));
312 Constant *C2 = cast<Constant>(Op1->getOperand(1));
314 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
315 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
316 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
319 WorkList.push_back(New);
320 I.setOperand(0, New);
321 I.setOperand(1, Folded);
328 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
329 // if the LHS is a constant zero (which is the 'negate' form).
331 static inline Value *dyn_castNegVal(Value *V) {
332 if (BinaryOperator::isNeg(V))
333 return BinaryOperator::getNegArgument(V);
335 // Constants can be considered to be negated values if they can be folded.
336 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
337 return ConstantExpr::getNeg(C);
341 static inline Value *dyn_castNotVal(Value *V) {
342 if (BinaryOperator::isNot(V))
343 return BinaryOperator::getNotArgument(V);
345 // Constants can be considered to be not'ed values...
346 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
347 return ConstantExpr::getNot(C);
351 // dyn_castFoldableMul - If this value is a multiply that can be folded into
352 // other computations (because it has a constant operand), return the
353 // non-constant operand of the multiply, and set CST to point to the multiplier.
354 // Otherwise, return null.
356 static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
357 if (V->hasOneUse() && V->getType()->isInteger())
358 if (Instruction *I = dyn_cast<Instruction>(V)) {
359 if (I->getOpcode() == Instruction::Mul)
360 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
361 return I->getOperand(0);
362 if (I->getOpcode() == Instruction::Shl)
363 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
364 // The multiplier is really 1 << CST.
365 Constant *One = ConstantInt::get(V->getType(), 1);
366 CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
367 return I->getOperand(0);
373 /// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
374 /// expression, return it.
375 static User *dyn_castGetElementPtr(Value *V) {
376 if (isa<GetElementPtrInst>(V)) return cast<User>(V);
377 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
378 if (CE->getOpcode() == Instruction::GetElementPtr)
379 return cast<User>(V);
383 // AddOne, SubOne - Add or subtract a constant one from an integer constant...
384 static ConstantInt *AddOne(ConstantInt *C) {
385 return cast<ConstantInt>(ConstantExpr::getAdd(C,
386 ConstantInt::get(C->getType(), 1)));
388 static ConstantInt *SubOne(ConstantInt *C) {
389 return cast<ConstantInt>(ConstantExpr::getSub(C,
390 ConstantInt::get(C->getType(), 1)));
393 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
394 /// this predicate to simplify operations downstream. V and Mask are known to
395 /// be the same type.
396 static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask,
397 unsigned Depth = 0) {
398 // Note, we cannot consider 'undef' to be "IsZero" here. The problem is that
399 // we cannot optimize based on the assumption that it is zero without changing
400 // to to an explicit zero. If we don't change it to zero, other code could
401 // optimized based on the contradictory assumption that it is non-zero.
402 // Because instcombine aggressively folds operations with undef args anyway,
403 // this won't lose us code quality.
404 if (Mask->isNullValue())
406 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
407 return ConstantExpr::getAnd(CI, Mask)->isNullValue();
409 if (Depth == 6) return false; // Limit search depth.
411 if (Instruction *I = dyn_cast<Instruction>(V)) {
412 switch (I->getOpcode()) {
413 case Instruction::And:
414 // (X & C1) & C2 == 0 iff C1 & C2 == 0.
415 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1))) {
416 ConstantIntegral *C1C2 =
417 cast<ConstantIntegral>(ConstantExpr::getAnd(CI, Mask));
418 if (MaskedValueIsZero(I->getOperand(0), C1C2, Depth+1))
421 // If either the LHS or the RHS are MaskedValueIsZero, the result is zero.
422 return MaskedValueIsZero(I->getOperand(1), Mask, Depth+1) ||
423 MaskedValueIsZero(I->getOperand(0), Mask, Depth+1);
424 case Instruction::Or:
425 case Instruction::Xor:
426 // If the LHS and the RHS are MaskedValueIsZero, the result is also zero.
427 return MaskedValueIsZero(I->getOperand(1), Mask, Depth+1) &&
428 MaskedValueIsZero(I->getOperand(0), Mask, Depth+1);
429 case Instruction::Select:
430 // If the T and F values are MaskedValueIsZero, the result is also zero.
431 return MaskedValueIsZero(I->getOperand(2), Mask, Depth+1) &&
432 MaskedValueIsZero(I->getOperand(1), Mask, Depth+1);
433 case Instruction::Cast: {
434 const Type *SrcTy = I->getOperand(0)->getType();
435 if (SrcTy == Type::BoolTy)
436 return (Mask->getRawValue() & 1) == 0;
438 if (SrcTy->isInteger()) {
439 // (cast <ty> X to int) & C2 == 0 iff <ty> could not have contained C2.
440 if (SrcTy->isUnsigned() && // Only handle zero ext.
441 ConstantExpr::getCast(Mask, SrcTy)->isNullValue())
444 // If this is a noop cast, recurse.
445 if ((SrcTy->isSigned() && SrcTy->getUnsignedVersion() == I->getType())||
446 SrcTy->getSignedVersion() == I->getType()) {
448 ConstantExpr::getCast(Mask, I->getOperand(0)->getType());
449 return MaskedValueIsZero(I->getOperand(0),
450 cast<ConstantIntegral>(NewMask), Depth+1);
455 case Instruction::Shl:
456 // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
457 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
458 return MaskedValueIsZero(I->getOperand(0),
459 cast<ConstantIntegral>(ConstantExpr::getUShr(Mask, SA)),
462 case Instruction::Shr:
463 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
464 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
465 if (I->getType()->isUnsigned()) {
466 Constant *C1 = ConstantIntegral::getAllOnesValue(I->getType());
467 C1 = ConstantExpr::getShr(C1, SA);
468 C1 = ConstantExpr::getAnd(C1, Mask);
469 if (C1->isNullValue())
479 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
480 // true when both operands are equal...
482 static bool isTrueWhenEqual(Instruction &I) {
483 return I.getOpcode() == Instruction::SetEQ ||
484 I.getOpcode() == Instruction::SetGE ||
485 I.getOpcode() == Instruction::SetLE;
488 /// AssociativeOpt - Perform an optimization on an associative operator. This
489 /// function is designed to check a chain of associative operators for a
490 /// potential to apply a certain optimization. Since the optimization may be
491 /// applicable if the expression was reassociated, this checks the chain, then
492 /// reassociates the expression as necessary to expose the optimization
493 /// opportunity. This makes use of a special Functor, which must define
494 /// 'shouldApply' and 'apply' methods.
496 template<typename Functor>
497 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
498 unsigned Opcode = Root.getOpcode();
499 Value *LHS = Root.getOperand(0);
501 // Quick check, see if the immediate LHS matches...
502 if (F.shouldApply(LHS))
503 return F.apply(Root);
505 // Otherwise, if the LHS is not of the same opcode as the root, return.
506 Instruction *LHSI = dyn_cast<Instruction>(LHS);
507 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
508 // Should we apply this transform to the RHS?
509 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
511 // If not to the RHS, check to see if we should apply to the LHS...
512 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
513 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
517 // If the functor wants to apply the optimization to the RHS of LHSI,
518 // reassociate the expression from ((? op A) op B) to (? op (A op B))
520 BasicBlock *BB = Root.getParent();
522 // Now all of the instructions are in the current basic block, go ahead
523 // and perform the reassociation.
524 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
526 // First move the selected RHS to the LHS of the root...
527 Root.setOperand(0, LHSI->getOperand(1));
529 // Make what used to be the LHS of the root be the user of the root...
530 Value *ExtraOperand = TmpLHSI->getOperand(1);
531 if (&Root == TmpLHSI) {
532 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
535 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
536 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
537 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
538 BasicBlock::iterator ARI = &Root; ++ARI;
539 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
542 // Now propagate the ExtraOperand down the chain of instructions until we
544 while (TmpLHSI != LHSI) {
545 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
546 // Move the instruction to immediately before the chain we are
547 // constructing to avoid breaking dominance properties.
548 NextLHSI->getParent()->getInstList().remove(NextLHSI);
549 BB->getInstList().insert(ARI, NextLHSI);
552 Value *NextOp = NextLHSI->getOperand(1);
553 NextLHSI->setOperand(1, ExtraOperand);
555 ExtraOperand = NextOp;
558 // Now that the instructions are reassociated, have the functor perform
559 // the transformation...
560 return F.apply(Root);
563 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
569 // AddRHS - Implements: X + X --> X << 1
572 AddRHS(Value *rhs) : RHS(rhs) {}
573 bool shouldApply(Value *LHS) const { return LHS == RHS; }
574 Instruction *apply(BinaryOperator &Add) const {
575 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
576 ConstantInt::get(Type::UByteTy, 1));
580 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
582 struct AddMaskingAnd {
584 AddMaskingAnd(Constant *c) : C2(c) {}
585 bool shouldApply(Value *LHS) const {
587 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
588 ConstantExpr::getAnd(C1, C2)->isNullValue();
590 Instruction *apply(BinaryOperator &Add) const {
591 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
595 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
597 if (isa<CastInst>(I)) {
598 if (Constant *SOC = dyn_cast<Constant>(SO))
599 return ConstantExpr::getCast(SOC, I.getType());
601 return IC->InsertNewInstBefore(new CastInst(SO, I.getType(),
602 SO->getName() + ".cast"), I);
605 // Figure out if the constant is the left or the right argument.
606 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
607 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
609 if (Constant *SOC = dyn_cast<Constant>(SO)) {
611 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
612 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
615 Value *Op0 = SO, *Op1 = ConstOperand;
619 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
620 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
621 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&I))
622 New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh");
624 assert(0 && "Unknown binary instruction type!");
627 return IC->InsertNewInstBefore(New, I);
630 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
631 // constant as the other operand, try to fold the binary operator into the
632 // select arguments. This also works for Cast instructions, which obviously do
633 // not have a second operand.
634 static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
636 // Don't modify shared select instructions
637 if (!SI->hasOneUse()) return 0;
638 Value *TV = SI->getOperand(1);
639 Value *FV = SI->getOperand(2);
641 if (isa<Constant>(TV) || isa<Constant>(FV)) {
642 // Bool selects with constant operands can be folded to logical ops.
643 if (SI->getType() == Type::BoolTy) return 0;
645 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
646 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
648 return new SelectInst(SI->getCondition(), SelectTrueVal,
655 /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
656 /// node as operand #0, see if we can fold the instruction into the PHI (which
657 /// is only possible if all operands to the PHI are constants).
658 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
659 PHINode *PN = cast<PHINode>(I.getOperand(0));
660 unsigned NumPHIValues = PN->getNumIncomingValues();
661 if (!PN->hasOneUse() || NumPHIValues == 0 ||
662 !isa<Constant>(PN->getIncomingValue(0))) return 0;
664 // Check to see if all of the operands of the PHI are constants. If not, we
665 // cannot do the transformation.
666 for (unsigned i = 1; i != NumPHIValues; ++i)
667 if (!isa<Constant>(PN->getIncomingValue(i)))
670 // Okay, we can do the transformation: create the new PHI node.
671 PHINode *NewPN = new PHINode(I.getType(), I.getName());
673 NewPN->reserveOperandSpace(PN->getNumOperands()/2);
674 InsertNewInstBefore(NewPN, *PN);
676 // Next, add all of the operands to the PHI.
677 if (I.getNumOperands() == 2) {
678 Constant *C = cast<Constant>(I.getOperand(1));
679 for (unsigned i = 0; i != NumPHIValues; ++i) {
680 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
681 NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
682 PN->getIncomingBlock(i));
685 assert(isa<CastInst>(I) && "Unary op should be a cast!");
686 const Type *RetTy = I.getType();
687 for (unsigned i = 0; i != NumPHIValues; ++i) {
688 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
689 NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
690 PN->getIncomingBlock(i));
693 return ReplaceInstUsesWith(I, NewPN);
696 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
697 bool Changed = SimplifyCommutative(I);
698 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
700 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
701 // X + undef -> undef
702 if (isa<UndefValue>(RHS))
703 return ReplaceInstUsesWith(I, RHS);
706 if (!I.getType()->isFloatingPoint()) { // NOTE: -0 + +0 = +0.
707 if (RHSC->isNullValue())
708 return ReplaceInstUsesWith(I, LHS);
709 } else if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
710 if (CFP->isExactlyValue(-0.0))
711 return ReplaceInstUsesWith(I, LHS);
714 // X + (signbit) --> X ^ signbit
715 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
716 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
717 uint64_t Val = CI->getRawValue() & (~0ULL >> (64- NumBits));
718 if (Val == (1ULL << (NumBits-1)))
719 return BinaryOperator::createXor(LHS, RHS);
722 if (isa<PHINode>(LHS))
723 if (Instruction *NV = FoldOpIntoPhi(I))
726 ConstantInt *XorRHS = 0;
728 if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
729 unsigned TySizeBits = I.getType()->getPrimitiveSizeInBits();
730 int64_t RHSSExt = cast<ConstantInt>(RHSC)->getSExtValue();
731 uint64_t RHSZExt = cast<ConstantInt>(RHSC)->getZExtValue();
733 uint64_t C0080Val = 1ULL << 31;
734 int64_t CFF80Val = -C0080Val;
737 if (TySizeBits > Size) {
739 // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
740 // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
741 if (RHSSExt == CFF80Val) {
742 if (XorRHS->getZExtValue() == C0080Val)
744 } else if (RHSZExt == C0080Val) {
745 if (XorRHS->getSExtValue() == CFF80Val)
749 // This is a sign extend if the top bits are known zero.
750 Constant *Mask = ConstantInt::getAllOnesValue(XorLHS->getType());
751 Mask = ConstantExpr::getShl(Mask,
752 ConstantInt::get(Type::UByteTy, 64-(TySizeBits-Size)));
753 if (!MaskedValueIsZero(XorLHS, cast<ConstantInt>(Mask)))
754 Size = 0; // Not a sign ext, but can't be any others either.
764 const Type *MiddleType = 0;
767 case 32: MiddleType = Type::IntTy; break;
768 case 16: MiddleType = Type::ShortTy; break;
769 case 8: MiddleType = Type::SByteTy; break;
772 Instruction *NewTrunc = new CastInst(XorLHS, MiddleType, "sext");
773 InsertNewInstBefore(NewTrunc, I);
774 return new CastInst(NewTrunc, I.getType());
780 if (I.getType()->isInteger()) {
781 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
783 if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
784 if (RHSI->getOpcode() == Instruction::Sub)
785 if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
786 return ReplaceInstUsesWith(I, RHSI->getOperand(0));
788 if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
789 if (LHSI->getOpcode() == Instruction::Sub)
790 if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
791 return ReplaceInstUsesWith(I, LHSI->getOperand(0));
796 if (Value *V = dyn_castNegVal(LHS))
797 return BinaryOperator::createSub(RHS, V);
800 if (!isa<Constant>(RHS))
801 if (Value *V = dyn_castNegVal(RHS))
802 return BinaryOperator::createSub(LHS, V);
806 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
807 if (X == RHS) // X*C + X --> X * (C+1)
808 return BinaryOperator::createMul(RHS, AddOne(C2));
810 // X*C1 + X*C2 --> X * (C1+C2)
812 if (X == dyn_castFoldableMul(RHS, C1))
813 return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2));
816 // X + X*C --> X * (C+1)
817 if (dyn_castFoldableMul(RHS, C2) == LHS)
818 return BinaryOperator::createMul(LHS, AddOne(C2));
821 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
822 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
823 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
825 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
827 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
828 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
829 return BinaryOperator::createSub(C, X);
832 // (X & FF00) + xx00 -> (X+xx00) & FF00
833 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
834 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
836 // See if all bits from the first bit set in the Add RHS up are included
837 // in the mask. First, get the rightmost bit.
838 uint64_t AddRHSV = CRHS->getRawValue();
840 // Form a mask of all bits from the lowest bit added through the top.
841 uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
842 AddRHSHighBits &= ~0ULL >> (64-C2->getType()->getPrimitiveSizeInBits());
844 // See if the and mask includes all of these bits.
845 uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue();
847 if (AddRHSHighBits == AddRHSHighBitsAnd) {
848 // Okay, the xform is safe. Insert the new add pronto.
849 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
851 return BinaryOperator::createAnd(NewAdd, C2);
856 // Try to fold constant add into select arguments.
857 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
858 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
862 return Changed ? &I : 0;
865 // isSignBit - Return true if the value represented by the constant only has the
866 // highest order bit set.
867 static bool isSignBit(ConstantInt *CI) {
868 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
869 return (CI->getRawValue() & (~0ULL >> (64-NumBits))) == (1ULL << (NumBits-1));
872 /// RemoveNoopCast - Strip off nonconverting casts from the value.
874 static Value *RemoveNoopCast(Value *V) {
875 if (CastInst *CI = dyn_cast<CastInst>(V)) {
876 const Type *CTy = CI->getType();
877 const Type *OpTy = CI->getOperand(0)->getType();
878 if (CTy->isInteger() && OpTy->isInteger()) {
879 if (CTy->getPrimitiveSizeInBits() == OpTy->getPrimitiveSizeInBits())
880 return RemoveNoopCast(CI->getOperand(0));
881 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
882 return RemoveNoopCast(CI->getOperand(0));
887 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
888 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
890 if (Op0 == Op1) // sub X, X -> 0
891 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
893 // If this is a 'B = x-(-A)', change to B = x+A...
894 if (Value *V = dyn_castNegVal(Op1))
895 return BinaryOperator::createAdd(Op0, V);
897 if (isa<UndefValue>(Op0))
898 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
899 if (isa<UndefValue>(Op1))
900 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
902 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
903 // Replace (-1 - A) with (~A)...
904 if (C->isAllOnesValue())
905 return BinaryOperator::createNot(Op1);
907 // C - ~X == X + (1+C)
909 if (match(Op1, m_Not(m_Value(X))))
910 return BinaryOperator::createAdd(X,
911 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
912 // -((uint)X >> 31) -> ((int)X >> 31)
913 // -((int)X >> 31) -> ((uint)X >> 31)
914 if (C->isNullValue()) {
915 Value *NoopCastedRHS = RemoveNoopCast(Op1);
916 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
917 if (SI->getOpcode() == Instruction::Shr)
918 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
920 if (SI->getType()->isSigned())
921 NewTy = SI->getType()->getUnsignedVersion();
923 NewTy = SI->getType()->getSignedVersion();
924 // Check to see if we are shifting out everything but the sign bit.
925 if (CU->getValue() == SI->getType()->getPrimitiveSizeInBits()-1) {
926 // Ok, the transformation is safe. Insert a cast of the incoming
927 // value, then the new shift, then the new cast.
928 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
929 SI->getOperand(0)->getName());
930 Value *InV = InsertNewInstBefore(FirstCast, I);
931 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
933 if (NewShift->getType() == I.getType())
936 InV = InsertNewInstBefore(NewShift, I);
937 return new CastInst(NewShift, I.getType());
943 // Try to fold constant sub into select arguments.
944 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
945 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
948 if (isa<PHINode>(Op0))
949 if (Instruction *NV = FoldOpIntoPhi(I))
953 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
954 if (Op1I->getOpcode() == Instruction::Add &&
955 !Op0->getType()->isFloatingPoint()) {
956 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
957 return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
958 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
959 return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
960 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
961 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
962 // C1-(X+C2) --> (C1-C2)-X
963 return BinaryOperator::createSub(ConstantExpr::getSub(CI1, CI2),
964 Op1I->getOperand(0));
968 if (Op1I->hasOneUse()) {
969 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
970 // is not used by anyone else...
972 if (Op1I->getOpcode() == Instruction::Sub &&
973 !Op1I->getType()->isFloatingPoint()) {
974 // Swap the two operands of the subexpr...
975 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
976 Op1I->setOperand(0, IIOp1);
977 Op1I->setOperand(1, IIOp0);
979 // Create the new top level add instruction...
980 return BinaryOperator::createAdd(Op0, Op1);
983 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
985 if (Op1I->getOpcode() == Instruction::And &&
986 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
987 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
990 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
991 return BinaryOperator::createAnd(Op0, NewNot);
994 // -(X sdiv C) -> (X sdiv -C)
995 if (Op1I->getOpcode() == Instruction::Div)
996 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
997 if (CSI->isNullValue())
998 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
999 return BinaryOperator::createDiv(Op1I->getOperand(0),
1000 ConstantExpr::getNeg(DivRHS));
1002 // X - X*C --> X * (1-C)
1003 ConstantInt *C2 = 0;
1004 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
1006 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
1007 return BinaryOperator::createMul(Op0, CP1);
1012 if (!Op0->getType()->isFloatingPoint())
1013 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
1014 if (Op0I->getOpcode() == Instruction::Add) {
1015 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
1016 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
1017 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
1018 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
1019 } else if (Op0I->getOpcode() == Instruction::Sub) {
1020 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
1021 return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName());
1025 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
1026 if (X == Op1) { // X*C - X --> X * (C-1)
1027 Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
1028 return BinaryOperator::createMul(Op1, CP1);
1031 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
1032 if (X == dyn_castFoldableMul(Op1, C2))
1033 return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
1038 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
1039 /// really just returns true if the most significant (sign) bit is set.
1040 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
1041 if (RHS->getType()->isSigned()) {
1042 // True if source is LHS < 0 or LHS <= -1
1043 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
1044 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
1046 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
1047 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
1048 // the size of the integer type.
1049 if (Opcode == Instruction::SetGE)
1050 return RHSC->getValue() ==
1051 1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1);
1052 if (Opcode == Instruction::SetGT)
1053 return RHSC->getValue() ==
1054 (1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1))-1;
1059 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
1060 bool Changed = SimplifyCommutative(I);
1061 Value *Op0 = I.getOperand(0);
1063 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
1064 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1066 // Simplify mul instructions with a constant RHS...
1067 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
1068 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
1070 // ((X << C1)*C2) == (X * (C2 << C1))
1071 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
1072 if (SI->getOpcode() == Instruction::Shl)
1073 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
1074 return BinaryOperator::createMul(SI->getOperand(0),
1075 ConstantExpr::getShl(CI, ShOp));
1077 if (CI->isNullValue())
1078 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
1079 if (CI->equalsInt(1)) // X * 1 == X
1080 return ReplaceInstUsesWith(I, Op0);
1081 if (CI->isAllOnesValue()) // X * -1 == 0 - X
1082 return BinaryOperator::createNeg(Op0, I.getName());
1084 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
1085 if (isPowerOf2_64(Val)) { // Replace X*(2^C) with X << C
1086 uint64_t C = Log2_64(Val);
1087 return new ShiftInst(Instruction::Shl, Op0,
1088 ConstantUInt::get(Type::UByteTy, C));
1090 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
1091 if (Op1F->isNullValue())
1092 return ReplaceInstUsesWith(I, Op1);
1094 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
1095 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
1096 if (Op1F->getValue() == 1.0)
1097 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
1100 // Try to fold constant mul into select arguments.
1101 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1102 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1105 if (isa<PHINode>(Op0))
1106 if (Instruction *NV = FoldOpIntoPhi(I))
1110 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
1111 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
1112 return BinaryOperator::createMul(Op0v, Op1v);
1114 // If one of the operands of the multiply is a cast from a boolean value, then
1115 // we know the bool is either zero or one, so this is a 'masking' multiply.
1116 // See if we can simplify things based on how the boolean was originally
1118 CastInst *BoolCast = 0;
1119 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
1120 if (CI->getOperand(0)->getType() == Type::BoolTy)
1123 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
1124 if (CI->getOperand(0)->getType() == Type::BoolTy)
1127 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
1128 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
1129 const Type *SCOpTy = SCIOp0->getType();
1131 // If the setcc is true iff the sign bit of X is set, then convert this
1132 // multiply into a shift/and combination.
1133 if (isa<ConstantInt>(SCIOp1) &&
1134 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
1135 // Shift the X value right to turn it into "all signbits".
1136 Constant *Amt = ConstantUInt::get(Type::UByteTy,
1137 SCOpTy->getPrimitiveSizeInBits()-1);
1138 if (SCIOp0->getType()->isUnsigned()) {
1139 const Type *NewTy = SCIOp0->getType()->getSignedVersion();
1140 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
1141 SCIOp0->getName()), I);
1145 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
1146 BoolCast->getOperand(0)->getName()+
1149 // If the multiply type is not the same as the source type, sign extend
1150 // or truncate to the multiply type.
1151 if (I.getType() != V->getType())
1152 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
1154 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
1155 return BinaryOperator::createAnd(V, OtherOp);
1160 return Changed ? &I : 0;
1163 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
1164 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1166 if (isa<UndefValue>(Op0)) // undef / X -> 0
1167 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1168 if (isa<UndefValue>(Op1))
1169 return ReplaceInstUsesWith(I, Op1); // X / undef -> undef
1171 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1173 if (RHS->equalsInt(1))
1174 return ReplaceInstUsesWith(I, Op0);
1177 if (RHS->isAllOnesValue())
1178 return BinaryOperator::createNeg(Op0);
1180 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
1181 if (LHS->getOpcode() == Instruction::Div)
1182 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
1183 // (X / C1) / C2 -> X / (C1*C2)
1184 return BinaryOperator::createDiv(LHS->getOperand(0),
1185 ConstantExpr::getMul(RHS, LHSRHS));
1188 // Check to see if this is an unsigned division with an exact power of 2,
1189 // if so, convert to a right shift.
1190 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1191 if (uint64_t Val = C->getValue()) // Don't break X / 0
1192 if (isPowerOf2_64(Val)) {
1193 uint64_t C = Log2_64(Val);
1194 return new ShiftInst(Instruction::Shr, Op0,
1195 ConstantUInt::get(Type::UByteTy, C));
1199 if (RHS->getType()->isSigned())
1200 if (Value *LHSNeg = dyn_castNegVal(Op0))
1201 return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS));
1203 if (!RHS->isNullValue()) {
1204 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1205 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1207 if (isa<PHINode>(Op0))
1208 if (Instruction *NV = FoldOpIntoPhi(I))
1213 // If this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1214 // transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'.
1215 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1216 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1217 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1218 if (STO->getValue() == 0) { // Couldn't be this argument.
1219 I.setOperand(1, SFO);
1221 } else if (SFO->getValue() == 0) {
1222 I.setOperand(1, STO);
1226 uint64_t TVA = STO->getValue(), FVA = SFO->getValue();
1227 if (isPowerOf2_64(TVA) && isPowerOf2_64(FVA)) {
1228 unsigned TSA = Log2_64(TVA), FSA = Log2_64(FVA);
1229 Constant *TC = ConstantUInt::get(Type::UByteTy, TSA);
1230 Instruction *TSI = new ShiftInst(Instruction::Shr, Op0,
1231 TC, SI->getName()+".t");
1232 TSI = InsertNewInstBefore(TSI, I);
1234 Constant *FC = ConstantUInt::get(Type::UByteTy, FSA);
1235 Instruction *FSI = new ShiftInst(Instruction::Shr, Op0,
1236 FC, SI->getName()+".f");
1237 FSI = InsertNewInstBefore(FSI, I);
1238 return new SelectInst(SI->getOperand(0), TSI, FSI);
1242 // 0 / X == 0, we don't need to preserve faults!
1243 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1244 if (LHS->equalsInt(0))
1245 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1247 if (I.getType()->isSigned()) {
1248 // If the top bits of both operands are zero (i.e. we can prove they are
1249 // unsigned inputs), turn this into a udiv.
1250 ConstantIntegral *MaskV = ConstantSInt::getMinValue(I.getType());
1251 if (MaskedValueIsZero(Op1, MaskV) && MaskedValueIsZero(Op0, MaskV)) {
1252 const Type *NTy = Op0->getType()->getUnsignedVersion();
1253 Instruction *LHS = new CastInst(Op0, NTy, Op0->getName());
1254 InsertNewInstBefore(LHS, I);
1256 if (Constant *R = dyn_cast<Constant>(Op1))
1257 RHS = ConstantExpr::getCast(R, NTy);
1259 RHS = InsertNewInstBefore(new CastInst(Op1, NTy, Op1->getName()), I);
1260 Instruction *Div = BinaryOperator::createDiv(LHS, RHS, I.getName());
1261 InsertNewInstBefore(Div, I);
1262 return new CastInst(Div, I.getType());
1265 // Known to be an unsigned division.
1266 if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
1267 // Turn A / (C1 << N), where C1 is "1<<C2" into A >> (N+C2) [udiv only].
1268 if (RHSI->getOpcode() == Instruction::Shl &&
1269 isa<ConstantUInt>(RHSI->getOperand(0))) {
1270 unsigned C1 = cast<ConstantUInt>(RHSI->getOperand(0))->getRawValue();
1271 if (isPowerOf2_64(C1)) {
1272 unsigned C2 = Log2_64(C1);
1273 Value *Add = RHSI->getOperand(1);
1275 Constant *C2V = ConstantUInt::get(Add->getType(), C2);
1276 Add = InsertNewInstBefore(BinaryOperator::createAdd(Add, C2V,
1279 return new ShiftInst(Instruction::Shr, Op0, Add);
1289 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
1290 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1291 if (I.getType()->isSigned()) {
1292 if (Value *RHSNeg = dyn_castNegVal(Op1))
1293 if (!isa<ConstantSInt>(RHSNeg) ||
1294 cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
1296 AddUsesToWorkList(I);
1297 I.setOperand(1, RHSNeg);
1301 // If the top bits of both operands are zero (i.e. we can prove they are
1302 // unsigned inputs), turn this into a urem.
1303 ConstantIntegral *MaskV = ConstantSInt::getMinValue(I.getType());
1304 if (MaskedValueIsZero(Op1, MaskV) && MaskedValueIsZero(Op0, MaskV)) {
1305 const Type *NTy = Op0->getType()->getUnsignedVersion();
1306 Instruction *LHS = new CastInst(Op0, NTy, Op0->getName());
1307 InsertNewInstBefore(LHS, I);
1309 if (Constant *R = dyn_cast<Constant>(Op1))
1310 RHS = ConstantExpr::getCast(R, NTy);
1312 RHS = InsertNewInstBefore(new CastInst(Op1, NTy, Op1->getName()), I);
1313 Instruction *Rem = BinaryOperator::createRem(LHS, RHS, I.getName());
1314 InsertNewInstBefore(Rem, I);
1315 return new CastInst(Rem, I.getType());
1319 if (isa<UndefValue>(Op0)) // undef % X -> 0
1320 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1321 if (isa<UndefValue>(Op1))
1322 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
1324 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1325 if (RHS->equalsInt(1)) // X % 1 == 0
1326 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1328 // Check to see if this is an unsigned remainder with an exact power of 2,
1329 // if so, convert to a bitwise and.
1330 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1331 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
1332 if (!(Val & (Val-1))) // Power of 2
1333 return BinaryOperator::createAnd(Op0,
1334 ConstantUInt::get(I.getType(), Val-1));
1336 if (!RHS->isNullValue()) {
1337 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1338 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1340 if (isa<PHINode>(Op0))
1341 if (Instruction *NV = FoldOpIntoPhi(I))
1346 // If this is 'urem X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1347 // transform this into: '(Cond ? (urem X, C1) : (urem X, C2))'.
1348 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1349 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1350 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1351 if (STO->getValue() == 0) { // Couldn't be this argument.
1352 I.setOperand(1, SFO);
1354 } else if (SFO->getValue() == 0) {
1355 I.setOperand(1, STO);
1359 if (!(STO->getValue() & (STO->getValue()-1)) &&
1360 !(SFO->getValue() & (SFO->getValue()-1))) {
1361 Value *TrueAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1362 SubOne(STO), SI->getName()+".t"), I);
1363 Value *FalseAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1364 SubOne(SFO), SI->getName()+".f"), I);
1365 return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
1369 // 0 % X == 0, we don't need to preserve faults!
1370 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1371 if (LHS->equalsInt(0))
1372 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1375 if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
1376 // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1) [urem only].
1377 if (I.getType()->isUnsigned() &&
1378 RHSI->getOpcode() == Instruction::Shl &&
1379 isa<ConstantUInt>(RHSI->getOperand(0))) {
1380 unsigned C1 = cast<ConstantUInt>(RHSI->getOperand(0))->getRawValue();
1381 if (isPowerOf2_64(C1)) {
1382 Constant *N1 = ConstantInt::getAllOnesValue(I.getType());
1383 Value *Add = InsertNewInstBefore(BinaryOperator::createAdd(RHSI, N1,
1385 return BinaryOperator::createAnd(Op0, Add);
1393 // isMaxValueMinusOne - return true if this is Max-1
1394 static bool isMaxValueMinusOne(const ConstantInt *C) {
1395 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
1396 // Calculate -1 casted to the right type...
1397 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1398 uint64_t Val = ~0ULL; // All ones
1399 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1400 return CU->getValue() == Val-1;
1403 const ConstantSInt *CS = cast<ConstantSInt>(C);
1405 // Calculate 0111111111..11111
1406 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1407 int64_t Val = INT64_MAX; // All ones
1408 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1409 return CS->getValue() == Val-1;
1412 // isMinValuePlusOne - return true if this is Min+1
1413 static bool isMinValuePlusOne(const ConstantInt *C) {
1414 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1415 return CU->getValue() == 1;
1417 const ConstantSInt *CS = cast<ConstantSInt>(C);
1419 // Calculate 1111111111000000000000
1420 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1421 int64_t Val = -1; // All ones
1422 Val <<= TypeBits-1; // Shift over to the right spot
1423 return CS->getValue() == Val+1;
1426 // isOneBitSet - Return true if there is exactly one bit set in the specified
1428 static bool isOneBitSet(const ConstantInt *CI) {
1429 uint64_t V = CI->getRawValue();
1430 return V && (V & (V-1)) == 0;
1433 #if 0 // Currently unused
1434 // isLowOnes - Return true if the constant is of the form 0+1+.
1435 static bool isLowOnes(const ConstantInt *CI) {
1436 uint64_t V = CI->getRawValue();
1438 // There won't be bits set in parts that the type doesn't contain.
1439 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1441 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1442 return U && V && (U & V) == 0;
1446 // isHighOnes - Return true if the constant is of the form 1+0+.
1447 // This is the same as lowones(~X).
1448 static bool isHighOnes(const ConstantInt *CI) {
1449 uint64_t V = ~CI->getRawValue();
1450 if (~V == 0) return false; // 0's does not match "1+"
1452 // There won't be bits set in parts that the type doesn't contain.
1453 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1455 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1456 return U && V && (U & V) == 0;
1460 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
1461 /// are carefully arranged to allow folding of expressions such as:
1463 /// (A < B) | (A > B) --> (A != B)
1465 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
1466 /// represents that the comparison is true if A == B, and bit value '1' is true
1469 static unsigned getSetCondCode(const SetCondInst *SCI) {
1470 switch (SCI->getOpcode()) {
1472 case Instruction::SetGT: return 1;
1473 case Instruction::SetEQ: return 2;
1474 case Instruction::SetGE: return 3;
1475 case Instruction::SetLT: return 4;
1476 case Instruction::SetNE: return 5;
1477 case Instruction::SetLE: return 6;
1480 assert(0 && "Invalid SetCC opcode!");
1485 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
1486 /// opcode and two operands into either a constant true or false, or a brand new
1487 /// SetCC instruction.
1488 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
1490 case 0: return ConstantBool::False;
1491 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
1492 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
1493 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
1494 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
1495 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
1496 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
1497 case 7: return ConstantBool::True;
1498 default: assert(0 && "Illegal SetCCCode!"); return 0;
1502 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1503 struct FoldSetCCLogical {
1506 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
1507 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
1508 bool shouldApply(Value *V) const {
1509 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
1510 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
1511 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
1514 Instruction *apply(BinaryOperator &Log) const {
1515 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
1516 if (SCI->getOperand(0) != LHS) {
1517 assert(SCI->getOperand(1) == LHS);
1518 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
1521 unsigned LHSCode = getSetCondCode(SCI);
1522 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
1524 switch (Log.getOpcode()) {
1525 case Instruction::And: Code = LHSCode & RHSCode; break;
1526 case Instruction::Or: Code = LHSCode | RHSCode; break;
1527 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
1528 default: assert(0 && "Illegal logical opcode!"); return 0;
1531 Value *RV = getSetCCValue(Code, LHS, RHS);
1532 if (Instruction *I = dyn_cast<Instruction>(RV))
1534 // Otherwise, it's a constant boolean value...
1535 return IC.ReplaceInstUsesWith(Log, RV);
1539 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
1540 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
1541 // guaranteed to be either a shift instruction or a binary operator.
1542 Instruction *InstCombiner::OptAndOp(Instruction *Op,
1543 ConstantIntegral *OpRHS,
1544 ConstantIntegral *AndRHS,
1545 BinaryOperator &TheAnd) {
1546 Value *X = Op->getOperand(0);
1547 Constant *Together = 0;
1548 if (!isa<ShiftInst>(Op))
1549 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
1551 switch (Op->getOpcode()) {
1552 case Instruction::Xor:
1553 if (Op->hasOneUse()) {
1554 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
1555 std::string OpName = Op->getName(); Op->setName("");
1556 Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
1557 InsertNewInstBefore(And, TheAnd);
1558 return BinaryOperator::createXor(And, Together);
1561 case Instruction::Or:
1562 if (Together == AndRHS) // (X | C) & C --> C
1563 return ReplaceInstUsesWith(TheAnd, AndRHS);
1565 if (Op->hasOneUse() && Together != OpRHS) {
1566 // (X | C1) & C2 --> (X | (C1&C2)) & C2
1567 std::string Op0Name = Op->getName(); Op->setName("");
1568 Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
1569 InsertNewInstBefore(Or, TheAnd);
1570 return BinaryOperator::createAnd(Or, AndRHS);
1573 case Instruction::Add:
1574 if (Op->hasOneUse()) {
1575 // Adding a one to a single bit bit-field should be turned into an XOR
1576 // of the bit. First thing to check is to see if this AND is with a
1577 // single bit constant.
1578 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
1580 // Clear bits that are not part of the constant.
1581 AndRHSV &= ~0ULL >> (64-AndRHS->getType()->getPrimitiveSizeInBits());
1583 // If there is only one bit set...
1584 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
1585 // Ok, at this point, we know that we are masking the result of the
1586 // ADD down to exactly one bit. If the constant we are adding has
1587 // no bits set below this bit, then we can eliminate the ADD.
1588 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
1590 // Check to see if any bits below the one bit set in AndRHSV are set.
1591 if ((AddRHS & (AndRHSV-1)) == 0) {
1592 // If not, the only thing that can effect the output of the AND is
1593 // the bit specified by AndRHSV. If that bit is set, the effect of
1594 // the XOR is to toggle the bit. If it is clear, then the ADD has
1596 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
1597 TheAnd.setOperand(0, X);
1600 std::string Name = Op->getName(); Op->setName("");
1601 // Pull the XOR out of the AND.
1602 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
1603 InsertNewInstBefore(NewAnd, TheAnd);
1604 return BinaryOperator::createXor(NewAnd, AndRHS);
1611 case Instruction::Shl: {
1612 // We know that the AND will not produce any of the bits shifted in, so if
1613 // the anded constant includes them, clear them now!
1615 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1616 Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
1617 Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
1619 if (CI == ShlMask) { // Masking out bits that the shift already masks
1620 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
1621 } else if (CI != AndRHS) { // Reducing bits set in and.
1622 TheAnd.setOperand(1, CI);
1627 case Instruction::Shr:
1628 // We know that the AND will not produce any of the bits shifted in, so if
1629 // the anded constant includes them, clear them now! This only applies to
1630 // unsigned shifts, because a signed shr may bring in set bits!
1632 if (AndRHS->getType()->isUnsigned()) {
1633 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1634 Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS);
1635 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1637 if (CI == ShrMask) { // Masking out bits that the shift already masks.
1638 return ReplaceInstUsesWith(TheAnd, Op);
1639 } else if (CI != AndRHS) {
1640 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
1643 } else { // Signed shr.
1644 // See if this is shifting in some sign extension, then masking it out
1646 if (Op->hasOneUse()) {
1647 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1648 Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS);
1649 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1650 if (CI == AndRHS) { // Masking out bits shifted in.
1651 // Make the argument unsigned.
1652 Value *ShVal = Op->getOperand(0);
1653 ShVal = InsertCastBefore(ShVal,
1654 ShVal->getType()->getUnsignedVersion(),
1656 ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal,
1657 OpRHS, Op->getName()),
1659 Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType());
1660 ShVal = InsertNewInstBefore(BinaryOperator::createAnd(ShVal, AndRHS2,
1663 return new CastInst(ShVal, Op->getType());
1673 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
1674 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
1675 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. IB is the location to
1676 /// insert new instructions.
1677 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
1678 bool Inside, Instruction &IB) {
1679 assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
1680 "Lo is not <= Hi in range emission code!");
1682 if (Lo == Hi) // Trivially false.
1683 return new SetCondInst(Instruction::SetNE, V, V);
1684 if (cast<ConstantIntegral>(Lo)->isMinValue())
1685 return new SetCondInst(Instruction::SetLT, V, Hi);
1687 Constant *AddCST = ConstantExpr::getNeg(Lo);
1688 Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
1689 InsertNewInstBefore(Add, IB);
1690 // Convert to unsigned for the comparison.
1691 const Type *UnsType = Add->getType()->getUnsignedVersion();
1692 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1693 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1694 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1695 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1698 if (Lo == Hi) // Trivially true.
1699 return new SetCondInst(Instruction::SetEQ, V, V);
1701 Hi = SubOne(cast<ConstantInt>(Hi));
1702 if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
1703 return new SetCondInst(Instruction::SetGT, V, Hi);
1705 // Emit X-Lo > Hi-Lo-1
1706 Constant *AddCST = ConstantExpr::getNeg(Lo);
1707 Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
1708 InsertNewInstBefore(Add, IB);
1709 // Convert to unsigned for the comparison.
1710 const Type *UnsType = Add->getType()->getUnsignedVersion();
1711 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1712 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1713 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1714 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1717 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
1718 // any number of 0s on either side. The 1s are allowed to wrap from LSB to
1719 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
1720 // not, since all 1s are not contiguous.
1721 static bool isRunOfOnes(ConstantIntegral *Val, unsigned &MB, unsigned &ME) {
1722 uint64_t V = Val->getRawValue();
1723 if (!isShiftedMask_64(V)) return false;
1725 // look for the first zero bit after the run of ones
1726 MB = 64-CountLeadingZeros_64((V - 1) ^ V);
1727 // look for the first non-zero bit
1728 ME = 64-CountLeadingZeros_64(V);
1734 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
1735 /// where isSub determines whether the operator is a sub. If we can fold one of
1736 /// the following xforms:
1738 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
1739 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
1740 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
1742 /// return (A +/- B).
1744 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
1745 ConstantIntegral *Mask, bool isSub,
1747 Instruction *LHSI = dyn_cast<Instruction>(LHS);
1748 if (!LHSI || LHSI->getNumOperands() != 2 ||
1749 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
1751 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
1753 switch (LHSI->getOpcode()) {
1755 case Instruction::And:
1756 if (ConstantExpr::getAnd(N, Mask) == Mask) {
1757 // If the AndRHS is a power of two minus one (0+1+), this is simple.
1758 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0)
1761 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
1762 // part, we don't need any explicit masks to take them out of A. If that
1763 // is all N is, ignore it.
1765 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
1766 Constant *Mask = ConstantInt::getAllOnesValue(RHS->getType());
1767 Mask = ConstantExpr::getUShr(Mask,
1768 ConstantInt::get(Type::UByteTy,
1770 if (MaskedValueIsZero(RHS, cast<ConstantIntegral>(Mask)))
1775 case Instruction::Or:
1776 case Instruction::Xor:
1777 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
1778 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0 &&
1779 ConstantExpr::getAnd(N, Mask)->isNullValue())
1786 New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold");
1788 New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold");
1789 return InsertNewInstBefore(New, I);
1792 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1793 bool Changed = SimplifyCommutative(I);
1794 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1796 if (isa<UndefValue>(Op1)) // X & undef -> 0
1797 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1801 return ReplaceInstUsesWith(I, Op1);
1803 if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) {
1805 if (AndRHS->isAllOnesValue())
1806 return ReplaceInstUsesWith(I, Op0);
1808 // and (and X, c1), c2 -> and (x, c1&c2). Handle this case here, before
1809 // calling MaskedValueIsZero, to avoid inefficient cases where we traipse
1810 // through many levels of ands.
1812 Value *X = 0; ConstantInt *C1 = 0;
1813 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))))
1814 return BinaryOperator::createAnd(X, ConstantExpr::getAnd(C1, AndRHS));
1817 if (MaskedValueIsZero(Op0, AndRHS)) // LHS & RHS == 0
1818 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1820 // If the mask is not masking out any bits, there is no reason to do the
1821 // and in the first place.
1822 ConstantIntegral *NotAndRHS =
1823 cast<ConstantIntegral>(ConstantExpr::getNot(AndRHS));
1824 if (MaskedValueIsZero(Op0, NotAndRHS))
1825 return ReplaceInstUsesWith(I, Op0);
1827 // Optimize a variety of ((val OP C1) & C2) combinations...
1828 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
1829 Instruction *Op0I = cast<Instruction>(Op0);
1830 Value *Op0LHS = Op0I->getOperand(0);
1831 Value *Op0RHS = Op0I->getOperand(1);
1832 switch (Op0I->getOpcode()) {
1833 case Instruction::Xor:
1834 case Instruction::Or:
1835 // (X ^ V) & C2 --> (X & C2) iff (V & C2) == 0
1836 // (X | V) & C2 --> (X & C2) iff (V & C2) == 0
1837 if (MaskedValueIsZero(Op0LHS, AndRHS))
1838 return BinaryOperator::createAnd(Op0RHS, AndRHS);
1839 if (MaskedValueIsZero(Op0RHS, AndRHS))
1840 return BinaryOperator::createAnd(Op0LHS, AndRHS);
1842 // If the mask is only needed on one incoming arm, push it up.
1843 if (Op0I->hasOneUse()) {
1844 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
1845 // Not masking anything out for the LHS, move to RHS.
1846 Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
1847 Op0RHS->getName()+".masked");
1848 InsertNewInstBefore(NewRHS, I);
1849 return BinaryOperator::create(
1850 cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
1852 if (!isa<Constant>(NotAndRHS) &&
1853 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
1854 // Not masking anything out for the RHS, move to LHS.
1855 Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
1856 Op0LHS->getName()+".masked");
1857 InsertNewInstBefore(NewLHS, I);
1858 return BinaryOperator::create(
1859 cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
1864 case Instruction::And:
1865 // (X & V) & C2 --> 0 iff (V & C2) == 0
1866 if (MaskedValueIsZero(Op0LHS, AndRHS) ||
1867 MaskedValueIsZero(Op0RHS, AndRHS))
1868 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1870 case Instruction::Add:
1871 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
1872 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1873 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1874 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
1875 return BinaryOperator::createAnd(V, AndRHS);
1876 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
1877 return BinaryOperator::createAnd(V, AndRHS); // Add commutes
1880 case Instruction::Sub:
1881 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
1882 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1883 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1884 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
1885 return BinaryOperator::createAnd(V, AndRHS);
1889 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1890 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
1892 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
1893 const Type *SrcTy = CI->getOperand(0)->getType();
1895 // If this is an integer truncation or change from signed-to-unsigned, and
1896 // if the source is an and/or with immediate, transform it. This
1897 // frequently occurs for bitfield accesses.
1898 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
1899 if (SrcTy->getPrimitiveSizeInBits() >=
1900 I.getType()->getPrimitiveSizeInBits() &&
1901 CastOp->getNumOperands() == 2)
1902 if (ConstantInt *AndCI =dyn_cast<ConstantInt>(CastOp->getOperand(1)))
1903 if (CastOp->getOpcode() == Instruction::And) {
1904 // Change: and (cast (and X, C1) to T), C2
1905 // into : and (cast X to T), trunc(C1)&C2
1906 // This will folds the two ands together, which may allow other
1908 Instruction *NewCast =
1909 new CastInst(CastOp->getOperand(0), I.getType(),
1910 CastOp->getName()+".shrunk");
1911 NewCast = InsertNewInstBefore(NewCast, I);
1913 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1914 C3 = ConstantExpr::getAnd(C3, AndRHS); // trunc(C1)&C2
1915 return BinaryOperator::createAnd(NewCast, C3);
1916 } else if (CastOp->getOpcode() == Instruction::Or) {
1917 // Change: and (cast (or X, C1) to T), C2
1918 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
1919 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1920 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
1921 return ReplaceInstUsesWith(I, AndRHS);
1926 // If this is an integer sign or zero extension instruction.
1927 if (SrcTy->isIntegral() &&
1928 SrcTy->getPrimitiveSizeInBits() <
1929 CI->getType()->getPrimitiveSizeInBits()) {
1931 if (SrcTy->isUnsigned()) {
1932 // See if this and is clearing out bits that are known to be zero
1933 // anyway (due to the zero extension).
1934 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1935 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1936 Constant *Result = ConstantExpr::getAnd(Mask, AndRHS);
1937 if (Result == Mask) // The "and" isn't doing anything, remove it.
1938 return ReplaceInstUsesWith(I, CI);
1939 if (Result != AndRHS) { // Reduce the and RHS constant.
1940 I.setOperand(1, Result);
1945 if (CI->hasOneUse() && SrcTy->isInteger()) {
1946 // We can only do this if all of the sign bits brought in are masked
1947 // out. Compute this by first getting 0000011111, then inverting
1949 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1950 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1951 Mask = ConstantExpr::getNot(Mask); // 1's in the new bits.
1952 if (ConstantExpr::getAnd(Mask, AndRHS)->isNullValue()) {
1953 // If the and is clearing all of the sign bits, change this to a
1954 // zero extension cast. To do this, cast the cast input to
1955 // unsigned, then to the requested size.
1956 Value *CastOp = CI->getOperand(0);
1958 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
1959 CI->getName()+".uns");
1960 NC = InsertNewInstBefore(NC, I);
1961 // Finally, insert a replacement for CI.
1962 NC = new CastInst(NC, CI->getType(), CI->getName());
1964 NC = InsertNewInstBefore(NC, I);
1965 WorkList.push_back(CI); // Delete CI later.
1966 I.setOperand(0, NC);
1967 return &I; // The AND operand was modified.
1974 // Try to fold constant and into select arguments.
1975 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1976 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1978 if (isa<PHINode>(Op0))
1979 if (Instruction *NV = FoldOpIntoPhi(I))
1983 Value *Op0NotVal = dyn_castNotVal(Op0);
1984 Value *Op1NotVal = dyn_castNotVal(Op1);
1986 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1987 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1989 // (~A & ~B) == (~(A | B)) - De Morgan's Law
1990 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1991 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
1992 I.getName()+".demorgan");
1993 InsertNewInstBefore(Or, I);
1994 return BinaryOperator::createNot(Or);
1997 if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
1998 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1999 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2002 Value *LHSVal, *RHSVal;
2003 ConstantInt *LHSCst, *RHSCst;
2004 Instruction::BinaryOps LHSCC, RHSCC;
2005 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
2006 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
2007 if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
2008 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
2009 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
2010 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
2011 // Ensure that the larger constant is on the RHS.
2012 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
2013 SetCondInst *LHS = cast<SetCondInst>(Op0);
2014 if (cast<ConstantBool>(Cmp)->getValue()) {
2015 std::swap(LHS, RHS);
2016 std::swap(LHSCst, RHSCst);
2017 std::swap(LHSCC, RHSCC);
2020 // At this point, we know we have have two setcc instructions
2021 // comparing a value against two constants and and'ing the result
2022 // together. Because of the above check, we know that we only have
2023 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
2024 // FoldSetCCLogical check above), that the two constants are not
2026 assert(LHSCst != RHSCst && "Compares not folded above?");
2029 default: assert(0 && "Unknown integer condition code!");
2030 case Instruction::SetEQ:
2032 default: assert(0 && "Unknown integer condition code!");
2033 case Instruction::SetEQ: // (X == 13 & X == 15) -> false
2034 case Instruction::SetGT: // (X == 13 & X > 15) -> false
2035 return ReplaceInstUsesWith(I, ConstantBool::False);
2036 case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
2037 case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
2038 return ReplaceInstUsesWith(I, LHS);
2040 case Instruction::SetNE:
2042 default: assert(0 && "Unknown integer condition code!");
2043 case Instruction::SetLT:
2044 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
2045 return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
2046 break; // (X != 13 & X < 15) -> no change
2047 case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
2048 case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
2049 return ReplaceInstUsesWith(I, RHS);
2050 case Instruction::SetNE:
2051 if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
2052 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2053 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
2054 LHSVal->getName()+".off");
2055 InsertNewInstBefore(Add, I);
2056 const Type *UnsType = Add->getType()->getUnsignedVersion();
2057 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
2058 AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
2059 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2060 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
2062 break; // (X != 13 & X != 15) -> no change
2065 case Instruction::SetLT:
2067 default: assert(0 && "Unknown integer condition code!");
2068 case Instruction::SetEQ: // (X < 13 & X == 15) -> false
2069 case Instruction::SetGT: // (X < 13 & X > 15) -> false
2070 return ReplaceInstUsesWith(I, ConstantBool::False);
2071 case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
2072 case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
2073 return ReplaceInstUsesWith(I, LHS);
2075 case Instruction::SetGT:
2077 default: assert(0 && "Unknown integer condition code!");
2078 case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
2079 return ReplaceInstUsesWith(I, LHS);
2080 case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
2081 return ReplaceInstUsesWith(I, RHS);
2082 case Instruction::SetNE:
2083 if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
2084 return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
2085 break; // (X > 13 & X != 15) -> no change
2086 case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
2087 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
2093 return Changed ? &I : 0;
2096 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
2097 bool Changed = SimplifyCommutative(I);
2098 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2100 if (isa<UndefValue>(Op1))
2101 return ReplaceInstUsesWith(I, // X | undef -> -1
2102 ConstantIntegral::getAllOnesValue(I.getType()));
2104 // or X, X = X or X, 0 == X
2105 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
2106 return ReplaceInstUsesWith(I, Op0);
2109 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2110 // If X is known to only contain bits that already exist in RHS, just
2111 // replace this instruction with RHS directly.
2112 if (MaskedValueIsZero(Op0,
2113 cast<ConstantIntegral>(ConstantExpr::getNot(RHS))))
2114 return ReplaceInstUsesWith(I, RHS);
2116 ConstantInt *C1 = 0; Value *X = 0;
2117 // (X & C1) | C2 --> (X | C2) & (C1|C2)
2118 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
2119 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0->getName());
2121 InsertNewInstBefore(Or, I);
2122 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
2125 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
2126 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
2127 std::string Op0Name = Op0->getName(); Op0->setName("");
2128 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
2129 InsertNewInstBefore(Or, I);
2130 return BinaryOperator::createXor(Or,
2131 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
2134 // Try to fold constant and into select arguments.
2135 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2136 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2138 if (isa<PHINode>(Op0))
2139 if (Instruction *NV = FoldOpIntoPhi(I))
2143 Value *A = 0, *B = 0;
2144 ConstantInt *C1 = 0, *C2 = 0;
2146 if (match(Op0, m_And(m_Value(A), m_Value(B))))
2147 if (A == Op1 || B == Op1) // (A & ?) | A --> A
2148 return ReplaceInstUsesWith(I, Op1);
2149 if (match(Op1, m_And(m_Value(A), m_Value(B))))
2150 if (A == Op0 || B == Op0) // A | (A & ?) --> A
2151 return ReplaceInstUsesWith(I, Op0);
2153 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
2154 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2155 MaskedValueIsZero(Op1, C1)) {
2156 Instruction *NOr = BinaryOperator::createOr(A, Op1, Op0->getName());
2158 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2161 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
2162 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2163 MaskedValueIsZero(Op0, C1)) {
2164 Instruction *NOr = BinaryOperator::createOr(A, Op0, Op1->getName());
2166 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2169 // (A & C1)|(B & C2)
2170 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2171 match(Op1, m_And(m_Value(B), m_ConstantInt(C2)))) {
2173 if (A == B) // (A & C1)|(A & C2) == A & (C1|C2)
2174 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
2177 // If we have: ((V + N) & C1) | (V & C2)
2178 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
2179 // replace with V+N.
2180 if (C1 == ConstantExpr::getNot(C2)) {
2181 Value *V1 = 0, *V2 = 0;
2182 if ((C2->getRawValue() & (C2->getRawValue()+1)) == 0 && // C2 == 0+1+
2183 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
2184 // Add commutes, try both ways.
2185 if (V1 == B && MaskedValueIsZero(V2, C2))
2186 return ReplaceInstUsesWith(I, A);
2187 if (V2 == B && MaskedValueIsZero(V1, C2))
2188 return ReplaceInstUsesWith(I, A);
2190 // Or commutes, try both ways.
2191 if ((C1->getRawValue() & (C1->getRawValue()+1)) == 0 &&
2192 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
2193 // Add commutes, try both ways.
2194 if (V1 == A && MaskedValueIsZero(V2, C1))
2195 return ReplaceInstUsesWith(I, B);
2196 if (V2 == A && MaskedValueIsZero(V1, C1))
2197 return ReplaceInstUsesWith(I, B);
2202 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
2203 if (A == Op1) // ~A | A == -1
2204 return ReplaceInstUsesWith(I,
2205 ConstantIntegral::getAllOnesValue(I.getType()));
2209 // Note, A is still live here!
2210 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
2212 return ReplaceInstUsesWith(I,
2213 ConstantIntegral::getAllOnesValue(I.getType()));
2215 // (~A | ~B) == (~(A & B)) - De Morgan's Law
2216 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
2217 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
2218 I.getName()+".demorgan"), I);
2219 return BinaryOperator::createNot(And);
2223 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
2224 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
2225 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2228 Value *LHSVal, *RHSVal;
2229 ConstantInt *LHSCst, *RHSCst;
2230 Instruction::BinaryOps LHSCC, RHSCC;
2231 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
2232 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
2233 if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
2234 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
2235 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
2236 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
2237 // Ensure that the larger constant is on the RHS.
2238 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
2239 SetCondInst *LHS = cast<SetCondInst>(Op0);
2240 if (cast<ConstantBool>(Cmp)->getValue()) {
2241 std::swap(LHS, RHS);
2242 std::swap(LHSCst, RHSCst);
2243 std::swap(LHSCC, RHSCC);
2246 // At this point, we know we have have two setcc instructions
2247 // comparing a value against two constants and or'ing the result
2248 // together. Because of the above check, we know that we only have
2249 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
2250 // FoldSetCCLogical check above), that the two constants are not
2252 assert(LHSCst != RHSCst && "Compares not folded above?");
2255 default: assert(0 && "Unknown integer condition code!");
2256 case Instruction::SetEQ:
2258 default: assert(0 && "Unknown integer condition code!");
2259 case Instruction::SetEQ:
2260 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
2261 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2262 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
2263 LHSVal->getName()+".off");
2264 InsertNewInstBefore(Add, I);
2265 const Type *UnsType = Add->getType()->getUnsignedVersion();
2266 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
2267 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
2268 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2269 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
2271 break; // (X == 13 | X == 15) -> no change
2273 case Instruction::SetGT: // (X == 13 | X > 14) -> no change
2275 case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
2276 case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
2277 return ReplaceInstUsesWith(I, RHS);
2280 case Instruction::SetNE:
2282 default: assert(0 && "Unknown integer condition code!");
2283 case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
2284 case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
2285 return ReplaceInstUsesWith(I, LHS);
2286 case Instruction::SetNE: // (X != 13 | X != 15) -> true
2287 case Instruction::SetLT: // (X != 13 | X < 15) -> true
2288 return ReplaceInstUsesWith(I, ConstantBool::True);
2291 case Instruction::SetLT:
2293 default: assert(0 && "Unknown integer condition code!");
2294 case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
2296 case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
2297 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
2298 case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
2299 case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
2300 return ReplaceInstUsesWith(I, RHS);
2303 case Instruction::SetGT:
2305 default: assert(0 && "Unknown integer condition code!");
2306 case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
2307 case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
2308 return ReplaceInstUsesWith(I, LHS);
2309 case Instruction::SetNE: // (X > 13 | X != 15) -> true
2310 case Instruction::SetLT: // (X > 13 | X < 15) -> true
2311 return ReplaceInstUsesWith(I, ConstantBool::True);
2317 return Changed ? &I : 0;
2320 // XorSelf - Implements: X ^ X --> 0
2323 XorSelf(Value *rhs) : RHS(rhs) {}
2324 bool shouldApply(Value *LHS) const { return LHS == RHS; }
2325 Instruction *apply(BinaryOperator &Xor) const {
2331 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
2332 bool Changed = SimplifyCommutative(I);
2333 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2335 if (isa<UndefValue>(Op1))
2336 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
2338 // xor X, X = 0, even if X is nested in a sequence of Xor's.
2339 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
2340 assert(Result == &I && "AssociativeOpt didn't work?");
2341 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2344 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2346 if (RHS->isNullValue())
2347 return ReplaceInstUsesWith(I, Op0);
2349 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2350 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
2351 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
2352 if (RHS == ConstantBool::True && SCI->hasOneUse())
2353 return new SetCondInst(SCI->getInverseCondition(),
2354 SCI->getOperand(0), SCI->getOperand(1));
2356 // ~(c-X) == X-c-1 == X+(-c-1)
2357 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
2358 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
2359 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
2360 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
2361 ConstantInt::get(I.getType(), 1));
2362 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
2365 // ~(~X & Y) --> (X | ~Y)
2366 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
2367 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
2368 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
2370 BinaryOperator::createNot(Op0I->getOperand(1),
2371 Op0I->getOperand(1)->getName()+".not");
2372 InsertNewInstBefore(NotY, I);
2373 return BinaryOperator::createOr(Op0NotVal, NotY);
2377 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
2378 switch (Op0I->getOpcode()) {
2379 case Instruction::Add:
2380 // ~(X-c) --> (-c-1)-X
2381 if (RHS->isAllOnesValue()) {
2382 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
2383 return BinaryOperator::createSub(
2384 ConstantExpr::getSub(NegOp0CI,
2385 ConstantInt::get(I.getType(), 1)),
2386 Op0I->getOperand(0));
2389 case Instruction::And:
2390 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
2391 if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue())
2392 return BinaryOperator::createOr(Op0, RHS);
2394 case Instruction::Or:
2395 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
2396 if (ConstantExpr::getAnd(RHS, Op0CI) == RHS)
2397 return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS));
2403 // Try to fold constant and into select arguments.
2404 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2405 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2407 if (isa<PHINode>(Op0))
2408 if (Instruction *NV = FoldOpIntoPhi(I))
2412 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
2414 return ReplaceInstUsesWith(I,
2415 ConstantIntegral::getAllOnesValue(I.getType()));
2417 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
2419 return ReplaceInstUsesWith(I,
2420 ConstantIntegral::getAllOnesValue(I.getType()));
2422 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
2423 if (Op1I->getOpcode() == Instruction::Or) {
2424 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
2425 cast<BinaryOperator>(Op1I)->swapOperands();
2427 std::swap(Op0, Op1);
2428 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
2430 std::swap(Op0, Op1);
2432 } else if (Op1I->getOpcode() == Instruction::Xor) {
2433 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
2434 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
2435 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
2436 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
2439 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
2440 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
2441 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
2442 cast<BinaryOperator>(Op0I)->swapOperands();
2443 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
2444 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
2445 Op1->getName()+".not"), I);
2446 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
2448 } else if (Op0I->getOpcode() == Instruction::Xor) {
2449 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
2450 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2451 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
2452 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2455 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
2456 ConstantInt *C1 = 0, *C2 = 0;
2457 if (match(Op0, m_And(m_Value(), m_ConstantInt(C1))) &&
2458 match(Op1, m_And(m_Value(), m_ConstantInt(C2))) &&
2459 ConstantExpr::getAnd(C1, C2)->isNullValue())
2460 return BinaryOperator::createOr(Op0, Op1);
2462 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
2463 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
2464 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2467 return Changed ? &I : 0;
2470 /// MulWithOverflow - Compute Result = In1*In2, returning true if the result
2471 /// overflowed for this type.
2472 static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2474 Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
2475 return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
2478 static bool isPositive(ConstantInt *C) {
2479 return cast<ConstantSInt>(C)->getValue() >= 0;
2482 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
2483 /// overflowed for this type.
2484 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2486 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
2488 if (In1->getType()->isUnsigned())
2489 return cast<ConstantUInt>(Result)->getValue() <
2490 cast<ConstantUInt>(In1)->getValue();
2491 if (isPositive(In1) != isPositive(In2))
2493 if (isPositive(In1))
2494 return cast<ConstantSInt>(Result)->getValue() <
2495 cast<ConstantSInt>(In1)->getValue();
2496 return cast<ConstantSInt>(Result)->getValue() >
2497 cast<ConstantSInt>(In1)->getValue();
2500 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
2501 /// code necessary to compute the offset from the base pointer (without adding
2502 /// in the base pointer). Return the result as a signed integer of intptr size.
2503 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
2504 TargetData &TD = IC.getTargetData();
2505 gep_type_iterator GTI = gep_type_begin(GEP);
2506 const Type *UIntPtrTy = TD.getIntPtrType();
2507 const Type *SIntPtrTy = UIntPtrTy->getSignedVersion();
2508 Value *Result = Constant::getNullValue(SIntPtrTy);
2510 // Build a mask for high order bits.
2511 uint64_t PtrSizeMask = ~0ULL;
2512 PtrSizeMask >>= 64-(TD.getPointerSize()*8);
2514 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
2515 Value *Op = GEP->getOperand(i);
2516 uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask;
2517 Constant *Scale = ConstantExpr::getCast(ConstantUInt::get(UIntPtrTy, Size),
2519 if (Constant *OpC = dyn_cast<Constant>(Op)) {
2520 if (!OpC->isNullValue()) {
2521 OpC = ConstantExpr::getCast(OpC, SIntPtrTy);
2522 Scale = ConstantExpr::getMul(OpC, Scale);
2523 if (Constant *RC = dyn_cast<Constant>(Result))
2524 Result = ConstantExpr::getAdd(RC, Scale);
2526 // Emit an add instruction.
2527 Result = IC.InsertNewInstBefore(
2528 BinaryOperator::createAdd(Result, Scale,
2529 GEP->getName()+".offs"), I);
2533 // Convert to correct type.
2534 Op = IC.InsertNewInstBefore(new CastInst(Op, SIntPtrTy,
2535 Op->getName()+".c"), I);
2537 // We'll let instcombine(mul) convert this to a shl if possible.
2538 Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
2539 GEP->getName()+".idx"), I);
2541 // Emit an add instruction.
2542 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
2543 GEP->getName()+".offs"), I);
2549 /// FoldGEPSetCC - Fold comparisons between a GEP instruction and something
2550 /// else. At this point we know that the GEP is on the LHS of the comparison.
2551 Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS,
2552 Instruction::BinaryOps Cond,
2554 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
2556 if (CastInst *CI = dyn_cast<CastInst>(RHS))
2557 if (isa<PointerType>(CI->getOperand(0)->getType()))
2558 RHS = CI->getOperand(0);
2560 Value *PtrBase = GEPLHS->getOperand(0);
2561 if (PtrBase == RHS) {
2562 // As an optimization, we don't actually have to compute the actual value of
2563 // OFFSET if this is a seteq or setne comparison, just return whether each
2564 // index is zero or not.
2565 if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) {
2566 Instruction *InVal = 0;
2567 gep_type_iterator GTI = gep_type_begin(GEPLHS);
2568 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
2570 if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
2571 if (isa<UndefValue>(C)) // undef index -> undef.
2572 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
2573 if (C->isNullValue())
2575 else if (TD->getTypeSize(GTI.getIndexedType()) == 0) {
2576 EmitIt = false; // This is indexing into a zero sized array?
2577 } else if (isa<ConstantInt>(C))
2578 return ReplaceInstUsesWith(I, // No comparison is needed here.
2579 ConstantBool::get(Cond == Instruction::SetNE));
2584 new SetCondInst(Cond, GEPLHS->getOperand(i),
2585 Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
2589 InVal = InsertNewInstBefore(InVal, I);
2590 InsertNewInstBefore(Comp, I);
2591 if (Cond == Instruction::SetNE) // True if any are unequal
2592 InVal = BinaryOperator::createOr(InVal, Comp);
2593 else // True if all are equal
2594 InVal = BinaryOperator::createAnd(InVal, Comp);
2602 ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0
2603 ConstantBool::get(Cond == Instruction::SetEQ));
2606 // Only lower this if the setcc is the only user of the GEP or if we expect
2607 // the result to fold to a constant!
2608 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
2609 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
2610 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
2611 return new SetCondInst(Cond, Offset,
2612 Constant::getNullValue(Offset->getType()));
2614 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
2615 // If the base pointers are different, but the indices are the same, just
2616 // compare the base pointer.
2617 if (PtrBase != GEPRHS->getOperand(0)) {
2618 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
2619 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
2620 GEPRHS->getOperand(0)->getType();
2622 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2623 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2624 IndicesTheSame = false;
2628 // If all indices are the same, just compare the base pointers.
2630 return new SetCondInst(Cond, GEPLHS->getOperand(0),
2631 GEPRHS->getOperand(0));
2633 // Otherwise, the base pointers are different and the indices are
2634 // different, bail out.
2638 // If one of the GEPs has all zero indices, recurse.
2639 bool AllZeros = true;
2640 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2641 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
2642 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
2647 return FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0),
2648 SetCondInst::getSwappedCondition(Cond), I);
2650 // If the other GEP has all zero indices, recurse.
2652 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2653 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
2654 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
2659 return FoldGEPSetCC(GEPLHS, GEPRHS->getOperand(0), Cond, I);
2661 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
2662 // If the GEPs only differ by one index, compare it.
2663 unsigned NumDifferences = 0; // Keep track of # differences.
2664 unsigned DiffOperand = 0; // The operand that differs.
2665 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2666 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2667 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
2668 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
2669 // Irreconcilable differences.
2673 if (NumDifferences++) break;
2678 if (NumDifferences == 0) // SAME GEP?
2679 return ReplaceInstUsesWith(I, // No comparison is needed here.
2680 ConstantBool::get(Cond == Instruction::SetEQ));
2681 else if (NumDifferences == 1) {
2682 Value *LHSV = GEPLHS->getOperand(DiffOperand);
2683 Value *RHSV = GEPRHS->getOperand(DiffOperand);
2685 // Convert the operands to signed values to make sure to perform a
2686 // signed comparison.
2687 const Type *NewTy = LHSV->getType()->getSignedVersion();
2688 if (LHSV->getType() != NewTy)
2689 LHSV = InsertNewInstBefore(new CastInst(LHSV, NewTy,
2690 LHSV->getName()), I);
2691 if (RHSV->getType() != NewTy)
2692 RHSV = InsertNewInstBefore(new CastInst(RHSV, NewTy,
2693 RHSV->getName()), I);
2694 return new SetCondInst(Cond, LHSV, RHSV);
2698 // Only lower this if the setcc is the only user of the GEP or if we expect
2699 // the result to fold to a constant!
2700 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
2701 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
2702 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
2703 Value *L = EmitGEPOffset(GEPLHS, I, *this);
2704 Value *R = EmitGEPOffset(GEPRHS, I, *this);
2705 return new SetCondInst(Cond, L, R);
2712 Instruction *InstCombiner::visitSetCondInst(SetCondInst &I) {
2713 bool Changed = SimplifyCommutative(I);
2714 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2715 const Type *Ty = Op0->getType();
2719 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
2721 if (isa<UndefValue>(Op1)) // X setcc undef -> undef
2722 return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
2724 // setcc <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
2725 // addresses never equal each other! We already know that Op0 != Op1.
2726 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
2727 isa<ConstantPointerNull>(Op0)) &&
2728 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
2729 isa<ConstantPointerNull>(Op1)))
2730 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
2732 // setcc's with boolean values can always be turned into bitwise operations
2733 if (Ty == Type::BoolTy) {
2734 switch (I.getOpcode()) {
2735 default: assert(0 && "Invalid setcc instruction!");
2736 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
2737 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
2738 InsertNewInstBefore(Xor, I);
2739 return BinaryOperator::createNot(Xor);
2741 case Instruction::SetNE:
2742 return BinaryOperator::createXor(Op0, Op1);
2744 case Instruction::SetGT:
2745 std::swap(Op0, Op1); // Change setgt -> setlt
2747 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
2748 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2749 InsertNewInstBefore(Not, I);
2750 return BinaryOperator::createAnd(Not, Op1);
2752 case Instruction::SetGE:
2753 std::swap(Op0, Op1); // Change setge -> setle
2755 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
2756 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2757 InsertNewInstBefore(Not, I);
2758 return BinaryOperator::createOr(Not, Op1);
2763 // See if we are doing a comparison between a constant and an instruction that
2764 // can be folded into the comparison.
2765 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2766 // Check to see if we are comparing against the minimum or maximum value...
2767 if (CI->isMinValue()) {
2768 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
2769 return ReplaceInstUsesWith(I, ConstantBool::False);
2770 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
2771 return ReplaceInstUsesWith(I, ConstantBool::True);
2772 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
2773 return BinaryOperator::createSetEQ(Op0, Op1);
2774 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
2775 return BinaryOperator::createSetNE(Op0, Op1);
2777 } else if (CI->isMaxValue()) {
2778 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
2779 return ReplaceInstUsesWith(I, ConstantBool::False);
2780 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
2781 return ReplaceInstUsesWith(I, ConstantBool::True);
2782 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
2783 return BinaryOperator::createSetEQ(Op0, Op1);
2784 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
2785 return BinaryOperator::createSetNE(Op0, Op1);
2787 // Comparing against a value really close to min or max?
2788 } else if (isMinValuePlusOne(CI)) {
2789 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
2790 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
2791 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
2792 return BinaryOperator::createSetNE(Op0, SubOne(CI));
2794 } else if (isMaxValueMinusOne(CI)) {
2795 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
2796 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
2797 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
2798 return BinaryOperator::createSetNE(Op0, AddOne(CI));
2801 // If we still have a setle or setge instruction, turn it into the
2802 // appropriate setlt or setgt instruction. Since the border cases have
2803 // already been handled above, this requires little checking.
2805 if (I.getOpcode() == Instruction::SetLE)
2806 return BinaryOperator::createSetLT(Op0, AddOne(CI));
2807 if (I.getOpcode() == Instruction::SetGE)
2808 return BinaryOperator::createSetGT(Op0, SubOne(CI));
2810 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
2811 switch (LHSI->getOpcode()) {
2812 case Instruction::And:
2813 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
2814 LHSI->getOperand(0)->hasOneUse()) {
2815 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
2816 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
2817 // happens a LOT in code produced by the C front-end, for bitfield
2819 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
2820 ConstantUInt *ShAmt;
2821 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
2822 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
2823 const Type *Ty = LHSI->getType();
2825 // We can fold this as long as we can't shift unknown bits
2826 // into the mask. This can only happen with signed shift
2827 // rights, as they sign-extend.
2829 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
2830 Shift->getType()->isUnsigned();
2832 // To test for the bad case of the signed shr, see if any
2833 // of the bits shifted in could be tested after the mask.
2834 int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue();
2835 if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
2837 Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal);
2839 ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
2840 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
2846 if (Shift->getOpcode() == Instruction::Shl)
2847 NewCst = ConstantExpr::getUShr(CI, ShAmt);
2849 NewCst = ConstantExpr::getShl(CI, ShAmt);
2851 // Check to see if we are shifting out any of the bits being
2853 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
2854 // If we shifted bits out, the fold is not going to work out.
2855 // As a special case, check to see if this means that the
2856 // result is always true or false now.
2857 if (I.getOpcode() == Instruction::SetEQ)
2858 return ReplaceInstUsesWith(I, ConstantBool::False);
2859 if (I.getOpcode() == Instruction::SetNE)
2860 return ReplaceInstUsesWith(I, ConstantBool::True);
2862 I.setOperand(1, NewCst);
2863 Constant *NewAndCST;
2864 if (Shift->getOpcode() == Instruction::Shl)
2865 NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
2867 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
2868 LHSI->setOperand(1, NewAndCST);
2869 LHSI->setOperand(0, Shift->getOperand(0));
2870 WorkList.push_back(Shift); // Shift is dead.
2871 AddUsesToWorkList(I);
2879 case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
2880 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2881 switch (I.getOpcode()) {
2883 case Instruction::SetEQ:
2884 case Instruction::SetNE: {
2885 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2887 // Check that the shift amount is in range. If not, don't perform
2888 // undefined shifts. When the shift is visited it will be
2890 if (ShAmt->getValue() >= TypeBits)
2893 // If we are comparing against bits always shifted out, the
2894 // comparison cannot succeed.
2896 ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
2897 if (Comp != CI) {// Comparing against a bit that we know is zero.
2898 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2899 Constant *Cst = ConstantBool::get(IsSetNE);
2900 return ReplaceInstUsesWith(I, Cst);
2903 if (LHSI->hasOneUse()) {
2904 // Otherwise strength reduce the shift into an and.
2905 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2906 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
2909 if (CI->getType()->isUnsigned()) {
2910 Mask = ConstantUInt::get(CI->getType(), Val);
2911 } else if (ShAmtVal != 0) {
2912 Mask = ConstantSInt::get(CI->getType(), Val);
2914 Mask = ConstantInt::getAllOnesValue(CI->getType());
2918 BinaryOperator::createAnd(LHSI->getOperand(0),
2919 Mask, LHSI->getName()+".mask");
2920 Value *And = InsertNewInstBefore(AndI, I);
2921 return new SetCondInst(I.getOpcode(), And,
2922 ConstantExpr::getUShr(CI, ShAmt));
2929 case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
2930 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2931 switch (I.getOpcode()) {
2933 case Instruction::SetEQ:
2934 case Instruction::SetNE: {
2936 // Check that the shift amount is in range. If not, don't perform
2937 // undefined shifts. When the shift is visited it will be
2939 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2940 if (ShAmt->getValue() >= TypeBits)
2943 // If we are comparing against bits always shifted out, the
2944 // comparison cannot succeed.
2946 ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
2948 if (Comp != CI) {// Comparing against a bit that we know is zero.
2949 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2950 Constant *Cst = ConstantBool::get(IsSetNE);
2951 return ReplaceInstUsesWith(I, Cst);
2954 if (LHSI->hasOneUse() || CI->isNullValue()) {
2955 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2957 // Otherwise strength reduce the shift into an and.
2958 uint64_t Val = ~0ULL; // All ones.
2959 Val <<= ShAmtVal; // Shift over to the right spot.
2962 if (CI->getType()->isUnsigned()) {
2963 Val &= ~0ULL >> (64-TypeBits);
2964 Mask = ConstantUInt::get(CI->getType(), Val);
2966 Mask = ConstantSInt::get(CI->getType(), Val);
2970 BinaryOperator::createAnd(LHSI->getOperand(0),
2971 Mask, LHSI->getName()+".mask");
2972 Value *And = InsertNewInstBefore(AndI, I);
2973 return new SetCondInst(I.getOpcode(), And,
2974 ConstantExpr::getShl(CI, ShAmt));
2982 case Instruction::Div:
2983 // Fold: (div X, C1) op C2 -> range check
2984 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
2985 // Fold this div into the comparison, producing a range check.
2986 // Determine, based on the divide type, what the range is being
2987 // checked. If there is an overflow on the low or high side, remember
2988 // it, otherwise compute the range [low, hi) bounding the new value.
2989 bool LoOverflow = false, HiOverflow = 0;
2990 ConstantInt *LoBound = 0, *HiBound = 0;
2993 bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
2995 Instruction::BinaryOps Opcode = I.getOpcode();
2997 if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
2998 } else if (LHSI->getType()->isUnsigned()) { // udiv
3000 LoOverflow = ProdOV;
3001 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
3002 } else if (isPositive(DivRHS)) { // Divisor is > 0.
3003 if (CI->isNullValue()) { // (X / pos) op 0
3005 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
3007 } else if (isPositive(CI)) { // (X / pos) op pos
3009 LoOverflow = ProdOV;
3010 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
3011 } else { // (X / pos) op neg
3012 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
3013 LoOverflow = AddWithOverflow(LoBound, Prod,
3014 cast<ConstantInt>(DivRHSH));
3016 HiOverflow = ProdOV;
3018 } else { // Divisor is < 0.
3019 if (CI->isNullValue()) { // (X / neg) op 0
3020 LoBound = AddOne(DivRHS);
3021 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
3022 if (HiBound == DivRHS)
3023 LoBound = 0; // - INTMIN = INTMIN
3024 } else if (isPositive(CI)) { // (X / neg) op pos
3025 HiOverflow = LoOverflow = ProdOV;
3027 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
3028 HiBound = AddOne(Prod);
3029 } else { // (X / neg) op neg
3031 LoOverflow = HiOverflow = ProdOV;
3032 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
3035 // Dividing by a negate swaps the condition.
3036 Opcode = SetCondInst::getSwappedCondition(Opcode);
3040 Value *X = LHSI->getOperand(0);
3042 default: assert(0 && "Unhandled setcc opcode!");
3043 case Instruction::SetEQ:
3044 if (LoOverflow && HiOverflow)
3045 return ReplaceInstUsesWith(I, ConstantBool::False);
3046 else if (HiOverflow)
3047 return new SetCondInst(Instruction::SetGE, X, LoBound);
3048 else if (LoOverflow)
3049 return new SetCondInst(Instruction::SetLT, X, HiBound);
3051 return InsertRangeTest(X, LoBound, HiBound, true, I);
3052 case Instruction::SetNE:
3053 if (LoOverflow && HiOverflow)
3054 return ReplaceInstUsesWith(I, ConstantBool::True);
3055 else if (HiOverflow)
3056 return new SetCondInst(Instruction::SetLT, X, LoBound);
3057 else if (LoOverflow)
3058 return new SetCondInst(Instruction::SetGE, X, HiBound);
3060 return InsertRangeTest(X, LoBound, HiBound, false, I);
3061 case Instruction::SetLT:
3063 return ReplaceInstUsesWith(I, ConstantBool::False);
3064 return new SetCondInst(Instruction::SetLT, X, LoBound);
3065 case Instruction::SetGT:
3067 return ReplaceInstUsesWith(I, ConstantBool::False);
3068 return new SetCondInst(Instruction::SetGE, X, HiBound);
3075 // Simplify seteq and setne instructions...
3076 if (I.getOpcode() == Instruction::SetEQ ||
3077 I.getOpcode() == Instruction::SetNE) {
3078 bool isSetNE = I.getOpcode() == Instruction::SetNE;
3080 // If the first operand is (and|or|xor) with a constant, and the second
3081 // operand is a constant, simplify a bit.
3082 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
3083 switch (BO->getOpcode()) {
3084 case Instruction::Rem:
3085 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
3086 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
3088 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1) {
3089 int64_t V = cast<ConstantSInt>(BO->getOperand(1))->getValue();
3090 if (isPowerOf2_64(V)) {
3091 unsigned L2 = Log2_64(V);
3092 const Type *UTy = BO->getType()->getUnsignedVersion();
3093 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
3095 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
3096 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
3097 RHSCst, BO->getName()), I);
3098 return BinaryOperator::create(I.getOpcode(), NewRem,
3099 Constant::getNullValue(UTy));
3104 case Instruction::Add:
3105 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
3106 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3107 if (BO->hasOneUse())
3108 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
3109 ConstantExpr::getSub(CI, BOp1C));
3110 } else if (CI->isNullValue()) {
3111 // Replace ((add A, B) != 0) with (A != -B) if A or B is
3112 // efficiently invertible, or if the add has just this one use.
3113 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
3115 if (Value *NegVal = dyn_castNegVal(BOp1))
3116 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
3117 else if (Value *NegVal = dyn_castNegVal(BOp0))
3118 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
3119 else if (BO->hasOneUse()) {
3120 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
3122 InsertNewInstBefore(Neg, I);
3123 return new SetCondInst(I.getOpcode(), BOp0, Neg);
3127 case Instruction::Xor:
3128 // For the xor case, we can xor two constants together, eliminating
3129 // the explicit xor.
3130 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
3131 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
3132 ConstantExpr::getXor(CI, BOC));
3135 case Instruction::Sub:
3136 // Replace (([sub|xor] A, B) != 0) with (A != B)
3137 if (CI->isNullValue())
3138 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
3142 case Instruction::Or:
3143 // If bits are being or'd in that are not present in the constant we
3144 // are comparing against, then the comparison could never succeed!
3145 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
3146 Constant *NotCI = ConstantExpr::getNot(CI);
3147 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
3148 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3152 case Instruction::And:
3153 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3154 // If bits are being compared against that are and'd out, then the
3155 // comparison can never succeed!
3156 if (!ConstantExpr::getAnd(CI,
3157 ConstantExpr::getNot(BOC))->isNullValue())
3158 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3160 // If we have ((X & C) == C), turn it into ((X & C) != 0).
3161 if (CI == BOC && isOneBitSet(CI))
3162 return new SetCondInst(isSetNE ? Instruction::SetEQ :
3163 Instruction::SetNE, Op0,
3164 Constant::getNullValue(CI->getType()));
3166 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
3167 // to be a signed value as appropriate.
3168 if (isSignBit(BOC)) {
3169 Value *X = BO->getOperand(0);
3170 // If 'X' is not signed, insert a cast now...
3171 if (!BOC->getType()->isSigned()) {
3172 const Type *DestTy = BOC->getType()->getSignedVersion();
3173 X = InsertCastBefore(X, DestTy, I);
3175 return new SetCondInst(isSetNE ? Instruction::SetLT :
3176 Instruction::SetGE, X,
3177 Constant::getNullValue(X->getType()));
3180 // ((X & ~7) == 0) --> X < 8
3181 if (CI->isNullValue() && isHighOnes(BOC)) {
3182 Value *X = BO->getOperand(0);
3183 Constant *NegX = ConstantExpr::getNeg(BOC);
3185 // If 'X' is signed, insert a cast now.
3186 if (NegX->getType()->isSigned()) {
3187 const Type *DestTy = NegX->getType()->getUnsignedVersion();
3188 X = InsertCastBefore(X, DestTy, I);
3189 NegX = ConstantExpr::getCast(NegX, DestTy);
3192 return new SetCondInst(isSetNE ? Instruction::SetGE :
3193 Instruction::SetLT, X, NegX);
3200 } else { // Not a SetEQ/SetNE
3201 // If the LHS is a cast from an integral value of the same size,
3202 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
3203 Value *CastOp = Cast->getOperand(0);
3204 const Type *SrcTy = CastOp->getType();
3205 unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits();
3206 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
3207 SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
3208 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
3209 "Source and destination signednesses should differ!");
3210 if (Cast->getType()->isSigned()) {
3211 // If this is a signed comparison, check for comparisons in the
3212 // vicinity of zero.
3213 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
3215 return BinaryOperator::createSetGT(CastOp,
3216 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize-1))-1));
3217 else if (I.getOpcode() == Instruction::SetGT &&
3218 cast<ConstantSInt>(CI)->getValue() == -1)
3219 // X > -1 => x < 128
3220 return BinaryOperator::createSetLT(CastOp,
3221 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize-1)));
3223 ConstantUInt *CUI = cast<ConstantUInt>(CI);
3224 if (I.getOpcode() == Instruction::SetLT &&
3225 CUI->getValue() == 1ULL << (SrcTySize-1))
3226 // X < 128 => X > -1
3227 return BinaryOperator::createSetGT(CastOp,
3228 ConstantSInt::get(SrcTy, -1));
3229 else if (I.getOpcode() == Instruction::SetGT &&
3230 CUI->getValue() == (1ULL << (SrcTySize-1))-1)
3232 return BinaryOperator::createSetLT(CastOp,
3233 Constant::getNullValue(SrcTy));
3240 // Handle setcc with constant RHS's that can be integer, FP or pointer.
3241 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
3242 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3243 switch (LHSI->getOpcode()) {
3244 case Instruction::GetElementPtr:
3245 if (RHSC->isNullValue()) {
3246 // Transform setcc GEP P, int 0, int 0, int 0, null -> setcc P, null
3247 bool isAllZeros = true;
3248 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
3249 if (!isa<Constant>(LHSI->getOperand(i)) ||
3250 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
3255 return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),
3256 Constant::getNullValue(LHSI->getOperand(0)->getType()));
3260 case Instruction::PHI:
3261 if (Instruction *NV = FoldOpIntoPhi(I))
3264 case Instruction::Select:
3265 // If either operand of the select is a constant, we can fold the
3266 // comparison into the select arms, which will cause one to be
3267 // constant folded and the select turned into a bitwise or.
3268 Value *Op1 = 0, *Op2 = 0;
3269 if (LHSI->hasOneUse()) {
3270 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
3271 // Fold the known value into the constant operand.
3272 Op1 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3273 // Insert a new SetCC of the other select operand.
3274 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3275 LHSI->getOperand(2), RHSC,
3277 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
3278 // Fold the known value into the constant operand.
3279 Op2 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3280 // Insert a new SetCC of the other select operand.
3281 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3282 LHSI->getOperand(1), RHSC,
3288 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
3293 // If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now.
3294 if (User *GEP = dyn_castGetElementPtr(Op0))
3295 if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I))
3297 if (User *GEP = dyn_castGetElementPtr(Op1))
3298 if (Instruction *NI = FoldGEPSetCC(GEP, Op0,
3299 SetCondInst::getSwappedCondition(I.getOpcode()), I))
3302 // Test to see if the operands of the setcc are casted versions of other
3303 // values. If the cast can be stripped off both arguments, we do so now.
3304 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3305 Value *CastOp0 = CI->getOperand(0);
3306 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
3307 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
3308 (I.getOpcode() == Instruction::SetEQ ||
3309 I.getOpcode() == Instruction::SetNE)) {
3310 // We keep moving the cast from the left operand over to the right
3311 // operand, where it can often be eliminated completely.
3314 // If operand #1 is a cast instruction, see if we can eliminate it as
3316 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
3317 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
3319 Op1 = CI2->getOperand(0);
3321 // If Op1 is a constant, we can fold the cast into the constant.
3322 if (Op1->getType() != Op0->getType())
3323 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
3324 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
3326 // Otherwise, cast the RHS right before the setcc
3327 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
3328 InsertNewInstBefore(cast<Instruction>(Op1), I);
3330 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
3333 // Handle the special case of: setcc (cast bool to X), <cst>
3334 // This comes up when you have code like
3337 // For generality, we handle any zero-extension of any operand comparison
3338 // with a constant or another cast from the same type.
3339 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
3340 if (Instruction *R = visitSetCondInstWithCastAndCast(I))
3343 return Changed ? &I : 0;
3346 // visitSetCondInstWithCastAndCast - Handle setcond (cast x to y), (cast/cst).
3347 // We only handle extending casts so far.
3349 Instruction *InstCombiner::visitSetCondInstWithCastAndCast(SetCondInst &SCI) {
3350 Value *LHSCIOp = cast<CastInst>(SCI.getOperand(0))->getOperand(0);
3351 const Type *SrcTy = LHSCIOp->getType();
3352 const Type *DestTy = SCI.getOperand(0)->getType();
3355 if (!DestTy->isIntegral() || !SrcTy->isIntegral())
3358 unsigned SrcBits = SrcTy->getPrimitiveSizeInBits();
3359 unsigned DestBits = DestTy->getPrimitiveSizeInBits();
3360 if (SrcBits >= DestBits) return 0; // Only handle extending cast.
3362 // Is this a sign or zero extension?
3363 bool isSignSrc = SrcTy->isSigned();
3364 bool isSignDest = DestTy->isSigned();
3366 if (CastInst *CI = dyn_cast<CastInst>(SCI.getOperand(1))) {
3367 // Not an extension from the same type?
3368 RHSCIOp = CI->getOperand(0);
3369 if (RHSCIOp->getType() != LHSCIOp->getType()) return 0;
3370 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(SCI.getOperand(1))) {
3371 // Compute the constant that would happen if we truncated to SrcTy then
3372 // reextended to DestTy.
3373 Constant *Res = ConstantExpr::getCast(CI, SrcTy);
3375 if (ConstantExpr::getCast(Res, DestTy) == CI) {
3378 // If the value cannot be represented in the shorter type, we cannot emit
3379 // a simple comparison.
3380 if (SCI.getOpcode() == Instruction::SetEQ)
3381 return ReplaceInstUsesWith(SCI, ConstantBool::False);
3382 if (SCI.getOpcode() == Instruction::SetNE)
3383 return ReplaceInstUsesWith(SCI, ConstantBool::True);
3385 // Evaluate the comparison for LT.
3387 if (DestTy->isSigned()) {
3388 // We're performing a signed comparison.
3390 // Signed extend and signed comparison.
3391 if (cast<ConstantSInt>(CI)->getValue() < 0) // X < (small) --> false
3392 Result = ConstantBool::False;
3394 Result = ConstantBool::True; // X < (large) --> true
3396 // Unsigned extend and signed comparison.
3397 if (cast<ConstantSInt>(CI)->getValue() < 0)
3398 Result = ConstantBool::False;
3400 Result = ConstantBool::True;
3403 // We're performing an unsigned comparison.
3405 // Unsigned extend & compare -> always true.
3406 Result = ConstantBool::True;
3408 // We're performing an unsigned comp with a sign extended value.
3409 // This is true if the input is >= 0. [aka >s -1]
3410 Constant *NegOne = ConstantIntegral::getAllOnesValue(SrcTy);
3411 Result = InsertNewInstBefore(BinaryOperator::createSetGT(LHSCIOp,
3412 NegOne, SCI.getName()), SCI);
3416 // Finally, return the value computed.
3417 if (SCI.getOpcode() == Instruction::SetLT) {
3418 return ReplaceInstUsesWith(SCI, Result);
3420 assert(SCI.getOpcode()==Instruction::SetGT &&"SetCC should be folded!");
3421 if (Constant *CI = dyn_cast<Constant>(Result))
3422 return ReplaceInstUsesWith(SCI, ConstantExpr::getNot(CI));
3424 return BinaryOperator::createNot(Result);
3431 // Okay, just insert a compare of the reduced operands now!
3432 return BinaryOperator::create(SCI.getOpcode(), LHSCIOp, RHSCIOp);
3435 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
3436 assert(I.getOperand(1)->getType() == Type::UByteTy);
3437 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3438 bool isLeftShift = I.getOpcode() == Instruction::Shl;
3440 // shl X, 0 == X and shr X, 0 == X
3441 // shl 0, X == 0 and shr 0, X == 0
3442 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
3443 Op0 == Constant::getNullValue(Op0->getType()))
3444 return ReplaceInstUsesWith(I, Op0);
3446 if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
3447 if (!isLeftShift && I.getType()->isSigned())
3448 return ReplaceInstUsesWith(I, Op0);
3449 else // undef << X -> 0 AND undef >>u X -> 0
3450 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3452 if (isa<UndefValue>(Op1)) {
3453 if (isLeftShift || I.getType()->isUnsigned())// X << undef, X >>u undef -> 0
3454 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3456 return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X
3459 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
3461 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
3462 if (CSI->isAllOnesValue())
3463 return ReplaceInstUsesWith(I, CSI);
3465 // Try to fold constant and into select arguments.
3466 if (isa<Constant>(Op0))
3467 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
3468 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3471 // See if we can turn a signed shr into an unsigned shr.
3472 if (!isLeftShift && I.getType()->isSigned()) {
3473 if (MaskedValueIsZero(Op0, ConstantInt::getMinValue(I.getType()))) {
3474 Value *V = InsertCastBefore(Op0, I.getType()->getUnsignedVersion(), I);
3475 V = InsertNewInstBefore(new ShiftInst(Instruction::Shr, V, Op1,
3477 return new CastInst(V, I.getType());
3481 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1))
3482 if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
3487 Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantUInt *Op1,
3489 bool isLeftShift = I.getOpcode() == Instruction::Shl;
3490 bool isSignedShift = Op0->getType()->isSigned();
3491 bool isUnsignedShift = !isSignedShift;
3493 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
3494 // of a signed value.
3496 unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits();
3497 if (Op1->getValue() >= TypeBits) {
3498 if (isUnsignedShift || isLeftShift)
3499 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
3501 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
3506 // ((X*C1) << C2) == (X * (C1 << C2))
3507 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
3508 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
3509 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
3510 return BinaryOperator::createMul(BO->getOperand(0),
3511 ConstantExpr::getShl(BOOp, Op1));
3513 // Try to fold constant and into select arguments.
3514 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3515 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3517 if (isa<PHINode>(Op0))
3518 if (Instruction *NV = FoldOpIntoPhi(I))
3521 if (Op0->hasOneUse()) {
3522 // If this is a SHL of a sign-extending cast, see if we can turn the input
3523 // into a zero extending cast (a simple strength reduction).
3524 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3525 const Type *SrcTy = CI->getOperand(0)->getType();
3526 if (isLeftShift && SrcTy->isInteger() && SrcTy->isSigned() &&
3527 SrcTy->getPrimitiveSizeInBits() <
3528 CI->getType()->getPrimitiveSizeInBits()) {
3529 // We can change it to a zero extension if we are shifting out all of
3530 // the sign extended bits. To check this, form a mask of all of the
3531 // sign extend bits, then shift them left and see if we have anything
3533 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); // 1111
3534 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); // 00001111
3535 Mask = ConstantExpr::getNot(Mask); // 1's in the sign bits: 11110000
3536 if (ConstantExpr::getShl(Mask, Op1)->isNullValue()) {
3537 // If the shift is nuking all of the sign bits, change this to a
3538 // zero extension cast. To do this, cast the cast input to
3539 // unsigned, then to the requested size.
3540 Value *CastOp = CI->getOperand(0);
3542 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
3543 CI->getName()+".uns");
3544 NC = InsertNewInstBefore(NC, I);
3545 // Finally, insert a replacement for CI.
3546 NC = new CastInst(NC, CI->getType(), CI->getName());
3548 NC = InsertNewInstBefore(NC, I);
3549 WorkList.push_back(CI); // Delete CI later.
3550 I.setOperand(0, NC);
3551 return &I; // The SHL operand was modified.
3556 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
3557 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
3560 switch (Op0BO->getOpcode()) {
3562 case Instruction::Add:
3563 case Instruction::And:
3564 case Instruction::Or:
3565 case Instruction::Xor:
3566 // These operators commute.
3567 // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
3568 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
3569 match(Op0BO->getOperand(1),
3570 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
3571 Instruction *YS = new ShiftInst(Instruction::Shl,
3572 Op0BO->getOperand(0), Op1,
3574 InsertNewInstBefore(YS, I); // (Y << C)
3575 Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
3577 Op0BO->getOperand(1)->getName());
3578 InsertNewInstBefore(X, I); // (X + (Y << C))
3579 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
3580 C2 = ConstantExpr::getShl(C2, Op1);
3581 return BinaryOperator::createAnd(X, C2);
3584 // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
3585 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
3586 match(Op0BO->getOperand(1),
3587 m_And(m_Shr(m_Value(V1), m_Value(V2)),
3588 m_ConstantInt(CC))) && V2 == Op1 &&
3589 cast<BinaryOperator>(Op0BO->getOperand(1))->getOperand(0)->hasOneUse()) {
3590 Instruction *YS = new ShiftInst(Instruction::Shl,
3591 Op0BO->getOperand(0), Op1,
3593 InsertNewInstBefore(YS, I); // (Y << C)
3595 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
3596 V1->getName()+".mask");
3597 InsertNewInstBefore(XM, I); // X & (CC << C)
3599 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
3603 case Instruction::Sub:
3604 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
3605 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
3606 match(Op0BO->getOperand(0),
3607 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
3608 Instruction *YS = new ShiftInst(Instruction::Shl,
3609 Op0BO->getOperand(1), Op1,
3611 InsertNewInstBefore(YS, I); // (Y << C)
3612 Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
3614 Op0BO->getOperand(0)->getName());
3615 InsertNewInstBefore(X, I); // (X + (Y << C))
3616 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
3617 C2 = ConstantExpr::getShl(C2, Op1);
3618 return BinaryOperator::createAnd(X, C2);
3621 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
3622 match(Op0BO->getOperand(0),
3623 m_And(m_Shr(m_Value(V1), m_Value(V2)),
3624 m_ConstantInt(CC))) && V2 == Op1 &&
3625 cast<BinaryOperator>(Op0BO->getOperand(0))->getOperand(0)->hasOneUse()) {
3626 Instruction *YS = new ShiftInst(Instruction::Shl,
3627 Op0BO->getOperand(1), Op1,
3629 InsertNewInstBefore(YS, I); // (Y << C)
3631 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
3632 V1->getName()+".mask");
3633 InsertNewInstBefore(XM, I); // X & (CC << C)
3635 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
3642 // If the operand is an bitwise operator with a constant RHS, and the
3643 // shift is the only use, we can pull it out of the shift.
3644 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
3645 bool isValid = true; // Valid only for And, Or, Xor
3646 bool highBitSet = false; // Transform if high bit of constant set?
3648 switch (Op0BO->getOpcode()) {
3649 default: isValid = false; break; // Do not perform transform!
3650 case Instruction::Add:
3651 isValid = isLeftShift;
3653 case Instruction::Or:
3654 case Instruction::Xor:
3657 case Instruction::And:
3662 // If this is a signed shift right, and the high bit is modified
3663 // by the logical operation, do not perform the transformation.
3664 // The highBitSet boolean indicates the value of the high bit of
3665 // the constant which would cause it to be modified for this
3668 if (isValid && !isLeftShift && isSignedShift) {
3669 uint64_t Val = Op0C->getRawValue();
3670 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
3674 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
3676 Instruction *NewShift =
3677 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), Op1,
3680 InsertNewInstBefore(NewShift, I);
3682 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
3689 // Find out if this is a shift of a shift by a constant.
3690 ShiftInst *ShiftOp = 0;
3691 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
3693 else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3694 // If this is a noop-integer case of a shift instruction, use the shift.
3695 if (CI->getOperand(0)->getType()->isInteger() &&
3696 CI->getOperand(0)->getType()->getPrimitiveSizeInBits() ==
3697 CI->getType()->getPrimitiveSizeInBits() &&
3698 isa<ShiftInst>(CI->getOperand(0))) {
3699 ShiftOp = cast<ShiftInst>(CI->getOperand(0));
3703 if (ShiftOp && isa<ConstantUInt>(ShiftOp->getOperand(1))) {
3704 // Find the operands and properties of the input shift. Note that the
3705 // signedness of the input shift may differ from the current shift if there
3706 // is a noop cast between the two.
3707 bool isShiftOfLeftShift = ShiftOp->getOpcode() == Instruction::Shl;
3708 bool isShiftOfSignedShift = ShiftOp->getType()->isSigned();
3709 bool isShiftOfUnsignedShift = !isShiftOfSignedShift;
3711 ConstantUInt *ShiftAmt1C = cast<ConstantUInt>(ShiftOp->getOperand(1));
3713 unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getValue();
3714 unsigned ShiftAmt2 = (unsigned)Op1->getValue();
3716 // Check for (A << c1) << c2 and (A >> c1) >> c2.
3717 if (isLeftShift == isShiftOfLeftShift) {
3718 // Do not fold these shifts if the first one is signed and the second one
3719 // is unsigned and this is a right shift. Further, don't do any folding
3721 if (isShiftOfSignedShift && isUnsignedShift && !isLeftShift)
3724 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift.
3725 if (Amt > Op0->getType()->getPrimitiveSizeInBits())
3726 Amt = Op0->getType()->getPrimitiveSizeInBits();
3728 Value *Op = ShiftOp->getOperand(0);
3729 if (isShiftOfSignedShift != isSignedShift)
3730 Op = InsertNewInstBefore(new CastInst(Op, I.getType(), "tmp"), I);
3731 return new ShiftInst(I.getOpcode(), Op,
3732 ConstantUInt::get(Type::UByteTy, Amt));
3735 // Check for (A << c1) >> c2 or (A >> c1) << c2. If we are dealing with
3736 // signed types, we can only support the (A >> c1) << c2 configuration,
3737 // because it can not turn an arbitrary bit of A into a sign bit.
3738 if (isUnsignedShift || isLeftShift) {
3739 // Calculate bitmask for what gets shifted off the edge.
3740 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
3742 C = ConstantExpr::getShl(C, ShiftAmt1C);
3744 C = ConstantExpr::getUShr(C, ShiftAmt1C);
3746 Value *Op = ShiftOp->getOperand(0);
3747 if (isShiftOfSignedShift != isSignedShift)
3748 Op = InsertNewInstBefore(new CastInst(Op, I.getType(),Op->getName()),I);
3751 BinaryOperator::createAnd(Op, C, Op->getName()+".mask");
3752 InsertNewInstBefore(Mask, I);
3754 // Figure out what flavor of shift we should use...
3755 if (ShiftAmt1 == ShiftAmt2) {
3756 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
3757 } else if (ShiftAmt1 < ShiftAmt2) {
3758 return new ShiftInst(I.getOpcode(), Mask,
3759 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
3760 } else if (isShiftOfUnsignedShift || isShiftOfLeftShift) {
3761 if (isShiftOfUnsignedShift && !isShiftOfLeftShift && isSignedShift) {
3762 // Make sure to emit an unsigned shift right, not a signed one.
3763 Mask = InsertNewInstBefore(new CastInst(Mask,
3764 Mask->getType()->getUnsignedVersion(),
3766 Mask = new ShiftInst(Instruction::Shr, Mask,
3767 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
3768 InsertNewInstBefore(Mask, I);
3769 return new CastInst(Mask, I.getType());
3771 return new ShiftInst(ShiftOp->getOpcode(), Mask,
3772 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
3775 // (X >>s C1) << C2 where C1 > C2 === (X >>s (C1-C2)) & mask
3776 Op = InsertNewInstBefore(new CastInst(Mask,
3777 I.getType()->getSignedVersion(),
3778 Mask->getName()), I);
3779 Instruction *Shift =
3780 new ShiftInst(ShiftOp->getOpcode(), Op,
3781 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
3782 InsertNewInstBefore(Shift, I);
3784 C = ConstantIntegral::getAllOnesValue(Shift->getType());
3785 C = ConstantExpr::getShl(C, Op1);
3786 Mask = BinaryOperator::createAnd(Shift, C, Op->getName()+".mask");
3787 InsertNewInstBefore(Mask, I);
3788 return new CastInst(Mask, I.getType());
3791 // We can handle signed (X << C1) >>s C2 if it's a sign extend. In
3792 // this case, C1 == C2 and C1 is 8, 16, or 32.
3793 if (ShiftAmt1 == ShiftAmt2) {
3794 const Type *SExtType = 0;
3795 switch (ShiftAmt1) {
3796 case 8 : SExtType = Type::SByteTy; break;
3797 case 16: SExtType = Type::ShortTy; break;
3798 case 32: SExtType = Type::IntTy; break;
3802 Instruction *NewTrunc = new CastInst(ShiftOp->getOperand(0),
3804 InsertNewInstBefore(NewTrunc, I);
3805 return new CastInst(NewTrunc, I.getType());
3820 /// getCastType - In the future, we will split the cast instruction into these
3821 /// various types. Until then, we have to do the analysis here.
3822 static CastType getCastType(const Type *Src, const Type *Dest) {
3823 assert(Src->isIntegral() && Dest->isIntegral() &&
3824 "Only works on integral types!");
3825 unsigned SrcSize = Src->getPrimitiveSizeInBits();
3826 unsigned DestSize = Dest->getPrimitiveSizeInBits();
3828 if (SrcSize == DestSize) return Noop;
3829 if (SrcSize > DestSize) return Truncate;
3830 if (Src->isSigned()) return Signext;
3835 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
3838 static bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
3839 const Type *DstTy, TargetData *TD) {
3841 // It is legal to eliminate the instruction if casting A->B->A if the sizes
3842 // are identical and the bits don't get reinterpreted (for example
3843 // int->float->int would not be allowed).
3844 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
3847 // If we are casting between pointer and integer types, treat pointers as
3848 // integers of the appropriate size for the code below.
3849 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
3850 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
3851 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
3853 // Allow free casting and conversion of sizes as long as the sign doesn't
3855 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
3856 CastType FirstCast = getCastType(SrcTy, MidTy);
3857 CastType SecondCast = getCastType(MidTy, DstTy);
3859 // Capture the effect of these two casts. If the result is a legal cast,
3860 // the CastType is stored here, otherwise a special code is used.
3861 static const unsigned CastResult[] = {
3862 // First cast is noop
3864 // First cast is a truncate
3865 1, 1, 4, 4, // trunc->extend is not safe to eliminate
3866 // First cast is a sign ext
3867 2, 5, 2, 4, // signext->zeroext never ok
3868 // First cast is a zero ext
3872 unsigned Result = CastResult[FirstCast*4+SecondCast];
3874 default: assert(0 && "Illegal table value!");
3879 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
3880 // truncates, we could eliminate more casts.
3881 return (unsigned)getCastType(SrcTy, DstTy) == Result;
3883 return false; // Not possible to eliminate this here.
3885 // Sign or zero extend followed by truncate is always ok if the result
3886 // is a truncate or noop.
3887 CastType ResultCast = getCastType(SrcTy, DstTy);
3888 if (ResultCast == Noop || ResultCast == Truncate)
3890 // Otherwise we are still growing the value, we are only safe if the
3891 // result will match the sign/zeroextendness of the result.
3892 return ResultCast == FirstCast;
3896 // If this is a cast from 'float -> double -> integer', cast from
3897 // 'float -> integer' directly, as the value isn't changed by the
3898 // float->double conversion.
3899 if (SrcTy->isFloatingPoint() && MidTy->isFloatingPoint() &&
3900 DstTy->isIntegral() &&
3901 SrcTy->getPrimitiveSize() < MidTy->getPrimitiveSize())
3907 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
3908 if (V->getType() == Ty || isa<Constant>(V)) return false;
3909 if (const CastInst *CI = dyn_cast<CastInst>(V))
3910 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
3916 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
3917 /// InsertBefore instruction. This is specialized a bit to avoid inserting
3918 /// casts that are known to not do anything...
3920 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
3921 Instruction *InsertBefore) {
3922 if (V->getType() == DestTy) return V;
3923 if (Constant *C = dyn_cast<Constant>(V))
3924 return ConstantExpr::getCast(C, DestTy);
3926 CastInst *CI = new CastInst(V, DestTy, V->getName());
3927 InsertNewInstBefore(CI, *InsertBefore);
3931 /// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
3932 /// expression. If so, decompose it, returning some value X, such that Val is
3935 static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
3937 assert(Val->getType() == Type::UIntTy && "Unexpected allocation size type!");
3938 if (ConstantUInt *CI = dyn_cast<ConstantUInt>(Val)) {
3939 Offset = CI->getValue();
3941 return ConstantUInt::get(Type::UIntTy, 0);
3942 } else if (Instruction *I = dyn_cast<Instruction>(Val)) {
3943 if (I->getNumOperands() == 2) {
3944 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(I->getOperand(1))) {
3945 if (I->getOpcode() == Instruction::Shl) {
3946 // This is a value scaled by '1 << the shift amt'.
3947 Scale = 1U << CUI->getValue();
3949 return I->getOperand(0);
3950 } else if (I->getOpcode() == Instruction::Mul) {
3951 // This value is scaled by 'CUI'.
3952 Scale = CUI->getValue();
3954 return I->getOperand(0);
3955 } else if (I->getOpcode() == Instruction::Add) {
3956 // We have X+C. Check to see if we really have (X*C2)+C1, where C1 is
3959 Value *SubVal = DecomposeSimpleLinearExpr(I->getOperand(0), SubScale,
3961 Offset += CUI->getValue();
3962 if (SubScale > 1 && (Offset % SubScale == 0)) {
3971 // Otherwise, we can't look past this.
3978 /// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
3979 /// try to eliminate the cast by moving the type information into the alloc.
3980 Instruction *InstCombiner::PromoteCastOfAllocation(CastInst &CI,
3981 AllocationInst &AI) {
3982 const PointerType *PTy = dyn_cast<PointerType>(CI.getType());
3983 if (!PTy) return 0; // Not casting the allocation to a pointer type.
3985 // Remove any uses of AI that are dead.
3986 assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
3987 std::vector<Instruction*> DeadUsers;
3988 for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
3989 Instruction *User = cast<Instruction>(*UI++);
3990 if (isInstructionTriviallyDead(User)) {
3991 while (UI != E && *UI == User)
3992 ++UI; // If this instruction uses AI more than once, don't break UI.
3994 // Add operands to the worklist.
3995 AddUsesToWorkList(*User);
3997 DEBUG(std::cerr << "IC: DCE: " << *User);
3999 User->eraseFromParent();
4000 removeFromWorkList(User);
4004 // Get the type really allocated and the type casted to.
4005 const Type *AllocElTy = AI.getAllocatedType();
4006 const Type *CastElTy = PTy->getElementType();
4007 if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
4009 unsigned AllocElTyAlign = TD->getTypeSize(AllocElTy);
4010 unsigned CastElTyAlign = TD->getTypeSize(CastElTy);
4011 if (CastElTyAlign < AllocElTyAlign) return 0;
4013 // If the allocation has multiple uses, only promote it if we are strictly
4014 // increasing the alignment of the resultant allocation. If we keep it the
4015 // same, we open the door to infinite loops of various kinds.
4016 if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return 0;
4018 uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
4019 uint64_t CastElTySize = TD->getTypeSize(CastElTy);
4020 if (CastElTySize == 0 || AllocElTySize == 0) return 0;
4022 // See if we can satisfy the modulus by pulling a scale out of the array
4024 unsigned ArraySizeScale, ArrayOffset;
4025 Value *NumElements = // See if the array size is a decomposable linear expr.
4026 DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
4028 // If we can now satisfy the modulus, by using a non-1 scale, we really can
4030 if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
4031 (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
4033 unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
4038 Amt = ConstantUInt::get(Type::UIntTy, Scale);
4039 if (ConstantUInt *CI = dyn_cast<ConstantUInt>(NumElements))
4040 Amt = ConstantExpr::getMul(CI, cast<ConstantUInt>(Amt));
4041 else if (Scale != 1) {
4042 Instruction *Tmp = BinaryOperator::createMul(Amt, NumElements, "tmp");
4043 Amt = InsertNewInstBefore(Tmp, AI);
4047 if (unsigned Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
4048 Value *Off = ConstantUInt::get(Type::UIntTy, Offset);
4049 Instruction *Tmp = BinaryOperator::createAdd(Amt, Off, "tmp");
4050 Amt = InsertNewInstBefore(Tmp, AI);
4053 std::string Name = AI.getName(); AI.setName("");
4054 AllocationInst *New;
4055 if (isa<MallocInst>(AI))
4056 New = new MallocInst(CastElTy, Amt, AI.getAlignment(), Name);
4058 New = new AllocaInst(CastElTy, Amt, AI.getAlignment(), Name);
4059 InsertNewInstBefore(New, AI);
4061 // If the allocation has multiple uses, insert a cast and change all things
4062 // that used it to use the new cast. This will also hack on CI, but it will
4064 if (!AI.hasOneUse()) {
4065 AddUsesToWorkList(AI);
4066 CastInst *NewCast = new CastInst(New, AI.getType(), "tmpcast");
4067 InsertNewInstBefore(NewCast, AI);
4068 AI.replaceAllUsesWith(NewCast);
4070 return ReplaceInstUsesWith(CI, New);
4074 // CastInst simplification
4076 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
4077 Value *Src = CI.getOperand(0);
4079 // If the user is casting a value to the same type, eliminate this cast
4081 if (CI.getType() == Src->getType())
4082 return ReplaceInstUsesWith(CI, Src);
4084 if (isa<UndefValue>(Src)) // cast undef -> undef
4085 return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
4087 // If casting the result of another cast instruction, try to eliminate this
4090 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
4091 Value *A = CSrc->getOperand(0);
4092 if (isEliminableCastOfCast(A->getType(), CSrc->getType(),
4093 CI.getType(), TD)) {
4094 // This instruction now refers directly to the cast's src operand. This
4095 // has a good chance of making CSrc dead.
4096 CI.setOperand(0, CSrc->getOperand(0));
4100 // If this is an A->B->A cast, and we are dealing with integral types, try
4101 // to convert this into a logical 'and' instruction.
4103 if (A->getType()->isInteger() &&
4104 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
4105 CSrc->getType()->isUnsigned() && // B->A cast must zero extend
4106 CSrc->getType()->getPrimitiveSizeInBits() <
4107 CI.getType()->getPrimitiveSizeInBits()&&
4108 A->getType()->getPrimitiveSizeInBits() ==
4109 CI.getType()->getPrimitiveSizeInBits()) {
4110 assert(CSrc->getType() != Type::ULongTy &&
4111 "Cannot have type bigger than ulong!");
4112 uint64_t AndValue = ~0ULL>>(64-CSrc->getType()->getPrimitiveSizeInBits());
4113 Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(),
4115 AndOp = ConstantExpr::getCast(AndOp, A->getType());
4116 Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
4117 if (And->getType() != CI.getType()) {
4118 And->setName(CSrc->getName()+".mask");
4119 InsertNewInstBefore(And, CI);
4120 And = new CastInst(And, CI.getType());
4126 // If this is a cast to bool, turn it into the appropriate setne instruction.
4127 if (CI.getType() == Type::BoolTy)
4128 return BinaryOperator::createSetNE(CI.getOperand(0),
4129 Constant::getNullValue(CI.getOperand(0)->getType()));
4131 // If casting the result of a getelementptr instruction with no offset, turn
4132 // this into a cast of the original pointer!
4134 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
4135 bool AllZeroOperands = true;
4136 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
4137 if (!isa<Constant>(GEP->getOperand(i)) ||
4138 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
4139 AllZeroOperands = false;
4142 if (AllZeroOperands) {
4143 CI.setOperand(0, GEP->getOperand(0));
4148 // If we are casting a malloc or alloca to a pointer to a type of the same
4149 // size, rewrite the allocation instruction to allocate the "right" type.
4151 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
4152 if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
4155 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
4156 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
4158 if (isa<PHINode>(Src))
4159 if (Instruction *NV = FoldOpIntoPhi(CI))
4162 // If the source value is an instruction with only this use, we can attempt to
4163 // propagate the cast into the instruction. Also, only handle integral types
4165 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
4166 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
4167 CI.getType()->isInteger()) { // Don't mess with casts to bool here
4168 const Type *DestTy = CI.getType();
4169 unsigned SrcBitSize = Src->getType()->getPrimitiveSizeInBits();
4170 unsigned DestBitSize = DestTy->getPrimitiveSizeInBits();
4172 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
4173 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
4175 switch (SrcI->getOpcode()) {
4176 case Instruction::Add:
4177 case Instruction::Mul:
4178 case Instruction::And:
4179 case Instruction::Or:
4180 case Instruction::Xor:
4181 // If we are discarding information, or just changing the sign, rewrite.
4182 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
4183 // Don't insert two casts if they cannot be eliminated. We allow two
4184 // casts to be inserted if the sizes are the same. This could only be
4185 // converting signedness, which is a noop.
4186 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
4187 !ValueRequiresCast(Op0, DestTy, TD)) {
4188 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
4189 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
4190 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
4191 ->getOpcode(), Op0c, Op1c);
4195 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
4196 if (SrcBitSize == 1 && SrcI->getOpcode() == Instruction::Xor &&
4197 Op1 == ConstantBool::True &&
4198 (!Op0->hasOneUse() || !isa<SetCondInst>(Op0))) {
4199 Value *New = InsertOperandCastBefore(Op0, DestTy, &CI);
4200 return BinaryOperator::createXor(New,
4201 ConstantInt::get(CI.getType(), 1));
4204 case Instruction::Shl:
4205 // Allow changing the sign of the source operand. Do not allow changing
4206 // the size of the shift, UNLESS the shift amount is a constant. We
4207 // mush not change variable sized shifts to a smaller size, because it
4208 // is undefined to shift more bits out than exist in the value.
4209 if (DestBitSize == SrcBitSize ||
4210 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
4211 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
4212 return new ShiftInst(Instruction::Shl, Op0c, Op1);
4215 case Instruction::Shr:
4216 // If this is a signed shr, and if all bits shifted in are about to be
4217 // truncated off, turn it into an unsigned shr to allow greater
4219 if (DestBitSize < SrcBitSize && Src->getType()->isSigned() &&
4220 isa<ConstantInt>(Op1)) {
4221 unsigned ShiftAmt = cast<ConstantUInt>(Op1)->getValue();
4222 if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
4223 // Convert to unsigned.
4224 Value *N1 = InsertOperandCastBefore(Op0,
4225 Op0->getType()->getUnsignedVersion(), &CI);
4226 // Insert the new shift, which is now unsigned.
4227 N1 = InsertNewInstBefore(new ShiftInst(Instruction::Shr, N1,
4228 Op1, Src->getName()), CI);
4229 return new CastInst(N1, CI.getType());
4234 case Instruction::SetNE:
4235 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
4236 if (Op1C->getRawValue() == 0) {
4237 // If the input only has the low bit set, simplify directly.
4239 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
4240 // cast (X != 0) to int --> X if X&~1 == 0
4241 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
4242 if (CI.getType() == Op0->getType())
4243 return ReplaceInstUsesWith(CI, Op0);
4245 return new CastInst(Op0, CI.getType());
4248 // If the input is an and with a single bit, shift then simplify.
4249 ConstantInt *AndRHS;
4250 if (match(Op0, m_And(m_Value(), m_ConstantInt(AndRHS))))
4251 if (AndRHS->getRawValue() &&
4252 (AndRHS->getRawValue() & (AndRHS->getRawValue()-1)) == 0) {
4253 unsigned ShiftAmt = Log2_64(AndRHS->getRawValue());
4254 // Perform an unsigned shr by shiftamt. Convert input to
4255 // unsigned if it is signed.
4257 if (In->getType()->isSigned())
4258 In = InsertNewInstBefore(new CastInst(In,
4259 In->getType()->getUnsignedVersion(), In->getName()),CI);
4260 // Insert the shift to put the result in the low bit.
4261 In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In,
4262 ConstantInt::get(Type::UByteTy, ShiftAmt),
4263 In->getName()+".lobit"), CI);
4264 if (CI.getType() == In->getType())
4265 return ReplaceInstUsesWith(CI, In);
4267 return new CastInst(In, CI.getType());
4272 case Instruction::SetEQ:
4273 // We if we are just checking for a seteq of a single bit and casting it
4274 // to an integer. If so, shift the bit to the appropriate place then
4275 // cast to integer to avoid the comparison.
4276 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
4277 // Is Op1C a power of two or zero?
4278 if ((Op1C->getRawValue() & Op1C->getRawValue()-1) == 0) {
4279 // cast (X == 1) to int -> X iff X has only the low bit set.
4280 if (Op1C->getRawValue() == 1) {
4282 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
4283 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
4284 if (CI.getType() == Op0->getType())
4285 return ReplaceInstUsesWith(CI, Op0);
4287 return new CastInst(Op0, CI.getType());
4299 /// GetSelectFoldableOperands - We want to turn code that looks like this:
4301 /// %D = select %cond, %C, %A
4303 /// %C = select %cond, %B, 0
4306 /// Assuming that the specified instruction is an operand to the select, return
4307 /// a bitmask indicating which operands of this instruction are foldable if they
4308 /// equal the other incoming value of the select.
4310 static unsigned GetSelectFoldableOperands(Instruction *I) {
4311 switch (I->getOpcode()) {
4312 case Instruction::Add:
4313 case Instruction::Mul:
4314 case Instruction::And:
4315 case Instruction::Or:
4316 case Instruction::Xor:
4317 return 3; // Can fold through either operand.
4318 case Instruction::Sub: // Can only fold on the amount subtracted.
4319 case Instruction::Shl: // Can only fold on the shift amount.
4320 case Instruction::Shr:
4323 return 0; // Cannot fold
4327 /// GetSelectFoldableConstant - For the same transformation as the previous
4328 /// function, return the identity constant that goes into the select.
4329 static Constant *GetSelectFoldableConstant(Instruction *I) {
4330 switch (I->getOpcode()) {
4331 default: assert(0 && "This cannot happen!"); abort();
4332 case Instruction::Add:
4333 case Instruction::Sub:
4334 case Instruction::Or:
4335 case Instruction::Xor:
4336 return Constant::getNullValue(I->getType());
4337 case Instruction::Shl:
4338 case Instruction::Shr:
4339 return Constant::getNullValue(Type::UByteTy);
4340 case Instruction::And:
4341 return ConstantInt::getAllOnesValue(I->getType());
4342 case Instruction::Mul:
4343 return ConstantInt::get(I->getType(), 1);
4347 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
4348 /// have the same opcode and only one use each. Try to simplify this.
4349 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
4351 if (TI->getNumOperands() == 1) {
4352 // If this is a non-volatile load or a cast from the same type,
4354 if (TI->getOpcode() == Instruction::Cast) {
4355 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
4358 return 0; // unknown unary op.
4361 // Fold this by inserting a select from the input values.
4362 SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
4363 FI->getOperand(0), SI.getName()+".v");
4364 InsertNewInstBefore(NewSI, SI);
4365 return new CastInst(NewSI, TI->getType());
4368 // Only handle binary operators here.
4369 if (!isa<ShiftInst>(TI) && !isa<BinaryOperator>(TI))
4372 // Figure out if the operations have any operands in common.
4373 Value *MatchOp, *OtherOpT, *OtherOpF;
4375 if (TI->getOperand(0) == FI->getOperand(0)) {
4376 MatchOp = TI->getOperand(0);
4377 OtherOpT = TI->getOperand(1);
4378 OtherOpF = FI->getOperand(1);
4379 MatchIsOpZero = true;
4380 } else if (TI->getOperand(1) == FI->getOperand(1)) {
4381 MatchOp = TI->getOperand(1);
4382 OtherOpT = TI->getOperand(0);
4383 OtherOpF = FI->getOperand(0);
4384 MatchIsOpZero = false;
4385 } else if (!TI->isCommutative()) {
4387 } else if (TI->getOperand(0) == FI->getOperand(1)) {
4388 MatchOp = TI->getOperand(0);
4389 OtherOpT = TI->getOperand(1);
4390 OtherOpF = FI->getOperand(0);
4391 MatchIsOpZero = true;
4392 } else if (TI->getOperand(1) == FI->getOperand(0)) {
4393 MatchOp = TI->getOperand(1);
4394 OtherOpT = TI->getOperand(0);
4395 OtherOpF = FI->getOperand(1);
4396 MatchIsOpZero = true;
4401 // If we reach here, they do have operations in common.
4402 SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
4403 OtherOpF, SI.getName()+".v");
4404 InsertNewInstBefore(NewSI, SI);
4406 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
4408 return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
4410 return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
4413 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI);
4415 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp);
4419 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
4420 Value *CondVal = SI.getCondition();
4421 Value *TrueVal = SI.getTrueValue();
4422 Value *FalseVal = SI.getFalseValue();
4424 // select true, X, Y -> X
4425 // select false, X, Y -> Y
4426 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
4427 if (C == ConstantBool::True)
4428 return ReplaceInstUsesWith(SI, TrueVal);
4430 assert(C == ConstantBool::False);
4431 return ReplaceInstUsesWith(SI, FalseVal);
4434 // select C, X, X -> X
4435 if (TrueVal == FalseVal)
4436 return ReplaceInstUsesWith(SI, TrueVal);
4438 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
4439 return ReplaceInstUsesWith(SI, FalseVal);
4440 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
4441 return ReplaceInstUsesWith(SI, TrueVal);
4442 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
4443 if (isa<Constant>(TrueVal))
4444 return ReplaceInstUsesWith(SI, TrueVal);
4446 return ReplaceInstUsesWith(SI, FalseVal);
4449 if (SI.getType() == Type::BoolTy)
4450 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
4451 if (C == ConstantBool::True) {
4452 // Change: A = select B, true, C --> A = or B, C
4453 return BinaryOperator::createOr(CondVal, FalseVal);
4455 // Change: A = select B, false, C --> A = and !B, C
4457 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4458 "not."+CondVal->getName()), SI);
4459 return BinaryOperator::createAnd(NotCond, FalseVal);
4461 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
4462 if (C == ConstantBool::False) {
4463 // Change: A = select B, C, false --> A = and B, C
4464 return BinaryOperator::createAnd(CondVal, TrueVal);
4466 // Change: A = select B, C, true --> A = or !B, C
4468 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4469 "not."+CondVal->getName()), SI);
4470 return BinaryOperator::createOr(NotCond, TrueVal);
4474 // Selecting between two integer constants?
4475 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
4476 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
4477 // select C, 1, 0 -> cast C to int
4478 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
4479 return new CastInst(CondVal, SI.getType());
4480 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
4481 // select C, 0, 1 -> cast !C to int
4483 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4484 "not."+CondVal->getName()), SI);
4485 return new CastInst(NotCond, SI.getType());
4488 // If one of the constants is zero (we know they can't both be) and we
4489 // have a setcc instruction with zero, and we have an 'and' with the
4490 // non-constant value, eliminate this whole mess. This corresponds to
4491 // cases like this: ((X & 27) ? 27 : 0)
4492 if (TrueValC->isNullValue() || FalseValC->isNullValue())
4493 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
4494 if ((IC->getOpcode() == Instruction::SetEQ ||
4495 IC->getOpcode() == Instruction::SetNE) &&
4496 isa<ConstantInt>(IC->getOperand(1)) &&
4497 cast<Constant>(IC->getOperand(1))->isNullValue())
4498 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
4499 if (ICA->getOpcode() == Instruction::And &&
4500 isa<ConstantInt>(ICA->getOperand(1)) &&
4501 (ICA->getOperand(1) == TrueValC ||
4502 ICA->getOperand(1) == FalseValC) &&
4503 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
4504 // Okay, now we know that everything is set up, we just don't
4505 // know whether we have a setne or seteq and whether the true or
4506 // false val is the zero.
4507 bool ShouldNotVal = !TrueValC->isNullValue();
4508 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
4511 V = InsertNewInstBefore(BinaryOperator::create(
4512 Instruction::Xor, V, ICA->getOperand(1)), SI);
4513 return ReplaceInstUsesWith(SI, V);
4517 // See if we are selecting two values based on a comparison of the two values.
4518 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
4519 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
4520 // Transform (X == Y) ? X : Y -> Y
4521 if (SCI->getOpcode() == Instruction::SetEQ)
4522 return ReplaceInstUsesWith(SI, FalseVal);
4523 // Transform (X != Y) ? X : Y -> X
4524 if (SCI->getOpcode() == Instruction::SetNE)
4525 return ReplaceInstUsesWith(SI, TrueVal);
4526 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
4528 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
4529 // Transform (X == Y) ? Y : X -> X
4530 if (SCI->getOpcode() == Instruction::SetEQ)
4531 return ReplaceInstUsesWith(SI, FalseVal);
4532 // Transform (X != Y) ? Y : X -> Y
4533 if (SCI->getOpcode() == Instruction::SetNE)
4534 return ReplaceInstUsesWith(SI, TrueVal);
4535 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
4539 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
4540 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
4541 if (TI->hasOneUse() && FI->hasOneUse()) {
4542 bool isInverse = false;
4543 Instruction *AddOp = 0, *SubOp = 0;
4545 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
4546 if (TI->getOpcode() == FI->getOpcode())
4547 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
4550 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
4551 // even legal for FP.
4552 if (TI->getOpcode() == Instruction::Sub &&
4553 FI->getOpcode() == Instruction::Add) {
4554 AddOp = FI; SubOp = TI;
4555 } else if (FI->getOpcode() == Instruction::Sub &&
4556 TI->getOpcode() == Instruction::Add) {
4557 AddOp = TI; SubOp = FI;
4561 Value *OtherAddOp = 0;
4562 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
4563 OtherAddOp = AddOp->getOperand(1);
4564 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
4565 OtherAddOp = AddOp->getOperand(0);
4569 // So at this point we know we have:
4570 // select C, (add X, Y), (sub X, ?)
4571 // We can do the transform profitably if either 'Y' = '?' or '?' is
4573 if (SubOp->getOperand(1) == AddOp ||
4574 isa<Constant>(SubOp->getOperand(1))) {
4576 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
4577 NegVal = ConstantExpr::getNeg(C);
4579 NegVal = InsertNewInstBefore(
4580 BinaryOperator::createNeg(SubOp->getOperand(1)), SI);
4583 Value *NewTrueOp = OtherAddOp;
4584 Value *NewFalseOp = NegVal;
4586 std::swap(NewTrueOp, NewFalseOp);
4587 Instruction *NewSel =
4588 new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
4590 NewSel = InsertNewInstBefore(NewSel, SI);
4591 return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
4597 // See if we can fold the select into one of our operands.
4598 if (SI.getType()->isInteger()) {
4599 // See the comment above GetSelectFoldableOperands for a description of the
4600 // transformation we are doing here.
4601 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
4602 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
4603 !isa<Constant>(FalseVal))
4604 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
4605 unsigned OpToFold = 0;
4606 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
4608 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
4613 Constant *C = GetSelectFoldableConstant(TVI);
4614 std::string Name = TVI->getName(); TVI->setName("");
4615 Instruction *NewSel =
4616 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
4618 InsertNewInstBefore(NewSel, SI);
4619 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
4620 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
4621 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
4622 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
4624 assert(0 && "Unknown instruction!!");
4629 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
4630 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
4631 !isa<Constant>(TrueVal))
4632 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
4633 unsigned OpToFold = 0;
4634 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
4636 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
4641 Constant *C = GetSelectFoldableConstant(FVI);
4642 std::string Name = FVI->getName(); FVI->setName("");
4643 Instruction *NewSel =
4644 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
4646 InsertNewInstBefore(NewSel, SI);
4647 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
4648 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
4649 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
4650 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
4652 assert(0 && "Unknown instruction!!");
4658 if (BinaryOperator::isNot(CondVal)) {
4659 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
4660 SI.setOperand(1, FalseVal);
4661 SI.setOperand(2, TrueVal);
4669 /// visitCallInst - CallInst simplification. This mostly only handles folding
4670 /// of intrinsic instructions. For normal calls, it allows visitCallSite to do
4671 /// the heavy lifting.
4673 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
4674 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
4675 if (!II) return visitCallSite(&CI);
4677 // Intrinsics cannot occur in an invoke, so handle them here instead of in
4679 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
4680 bool Changed = false;
4682 // memmove/cpy/set of zero bytes is a noop.
4683 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
4684 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
4686 // FIXME: Increase alignment here.
4688 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
4689 if (CI->getRawValue() == 1) {
4690 // Replace the instruction with just byte operations. We would
4691 // transform other cases to loads/stores, but we don't know if
4692 // alignment is sufficient.
4696 // If we have a memmove and the source operation is a constant global,
4697 // then the source and dest pointers can't alias, so we can change this
4698 // into a call to memcpy.
4699 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(II))
4700 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
4701 if (GVSrc->isConstant()) {
4702 Module *M = CI.getParent()->getParent()->getParent();
4703 Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
4704 CI.getCalledFunction()->getFunctionType());
4705 CI.setOperand(0, MemCpy);
4709 if (Changed) return II;
4710 } else if (DbgStopPointInst *SPI = dyn_cast<DbgStopPointInst>(II)) {
4711 // If this stoppoint is at the same source location as the previous
4712 // stoppoint in the chain, it is not needed.
4713 if (DbgStopPointInst *PrevSPI =
4714 dyn_cast<DbgStopPointInst>(SPI->getChain()))
4715 if (SPI->getLineNo() == PrevSPI->getLineNo() &&
4716 SPI->getColNo() == PrevSPI->getColNo()) {
4717 SPI->replaceAllUsesWith(PrevSPI);
4718 return EraseInstFromFunction(CI);
4721 switch (II->getIntrinsicID()) {
4723 case Intrinsic::stackrestore: {
4724 // If the save is right next to the restore, remove the restore. This can
4725 // happen when variable allocas are DCE'd.
4726 if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
4727 if (SS->getIntrinsicID() == Intrinsic::stacksave) {
4728 BasicBlock::iterator BI = SS;
4730 return EraseInstFromFunction(CI);
4734 // If the stack restore is in a return/unwind block and if there are no
4735 // allocas or calls between the restore and the return, nuke the restore.
4736 TerminatorInst *TI = II->getParent()->getTerminator();
4737 if (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)) {
4738 BasicBlock::iterator BI = II;
4739 bool CannotRemove = false;
4740 for (++BI; &*BI != TI; ++BI) {
4741 if (isa<AllocaInst>(BI) ||
4742 (isa<CallInst>(BI) && !isa<IntrinsicInst>(BI))) {
4743 CannotRemove = true;
4748 return EraseInstFromFunction(CI);
4755 return visitCallSite(II);
4758 // InvokeInst simplification
4760 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
4761 return visitCallSite(&II);
4764 // visitCallSite - Improvements for call and invoke instructions.
4766 Instruction *InstCombiner::visitCallSite(CallSite CS) {
4767 bool Changed = false;
4769 // If the callee is a constexpr cast of a function, attempt to move the cast
4770 // to the arguments of the call/invoke.
4771 if (transformConstExprCastCall(CS)) return 0;
4773 Value *Callee = CS.getCalledValue();
4775 if (Function *CalleeF = dyn_cast<Function>(Callee))
4776 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
4777 Instruction *OldCall = CS.getInstruction();
4778 // If the call and callee calling conventions don't match, this call must
4779 // be unreachable, as the call is undefined.
4780 new StoreInst(ConstantBool::True,
4781 UndefValue::get(PointerType::get(Type::BoolTy)), OldCall);
4782 if (!OldCall->use_empty())
4783 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
4784 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
4785 return EraseInstFromFunction(*OldCall);
4789 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
4790 // This instruction is not reachable, just remove it. We insert a store to
4791 // undef so that we know that this code is not reachable, despite the fact
4792 // that we can't modify the CFG here.
4793 new StoreInst(ConstantBool::True,
4794 UndefValue::get(PointerType::get(Type::BoolTy)),
4795 CS.getInstruction());
4797 if (!CS.getInstruction()->use_empty())
4798 CS.getInstruction()->
4799 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
4801 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
4802 // Don't break the CFG, insert a dummy cond branch.
4803 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
4804 ConstantBool::True, II);
4806 return EraseInstFromFunction(*CS.getInstruction());
4809 const PointerType *PTy = cast<PointerType>(Callee->getType());
4810 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
4811 if (FTy->isVarArg()) {
4812 // See if we can optimize any arguments passed through the varargs area of
4814 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
4815 E = CS.arg_end(); I != E; ++I)
4816 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
4817 // If this cast does not effect the value passed through the varargs
4818 // area, we can eliminate the use of the cast.
4819 Value *Op = CI->getOperand(0);
4820 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
4827 return Changed ? CS.getInstruction() : 0;
4830 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
4831 // attempt to move the cast to the arguments of the call/invoke.
4833 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
4834 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
4835 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
4836 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
4838 Function *Callee = cast<Function>(CE->getOperand(0));
4839 Instruction *Caller = CS.getInstruction();
4841 // Okay, this is a cast from a function to a different type. Unless doing so
4842 // would cause a type conversion of one of our arguments, change this call to
4843 // be a direct call with arguments casted to the appropriate types.
4845 const FunctionType *FT = Callee->getFunctionType();
4846 const Type *OldRetTy = Caller->getType();
4848 // Check to see if we are changing the return type...
4849 if (OldRetTy != FT->getReturnType()) {
4850 if (Callee->isExternal() &&
4851 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
4852 !Caller->use_empty())
4853 return false; // Cannot transform this return value...
4855 // If the callsite is an invoke instruction, and the return value is used by
4856 // a PHI node in a successor, we cannot change the return type of the call
4857 // because there is no place to put the cast instruction (without breaking
4858 // the critical edge). Bail out in this case.
4859 if (!Caller->use_empty())
4860 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
4861 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
4863 if (PHINode *PN = dyn_cast<PHINode>(*UI))
4864 if (PN->getParent() == II->getNormalDest() ||
4865 PN->getParent() == II->getUnwindDest())
4869 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
4870 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
4872 CallSite::arg_iterator AI = CS.arg_begin();
4873 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
4874 const Type *ParamTy = FT->getParamType(i);
4875 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
4876 if (Callee->isExternal() && !isConvertible) return false;
4879 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
4880 Callee->isExternal())
4881 return false; // Do not delete arguments unless we have a function body...
4883 // Okay, we decided that this is a safe thing to do: go ahead and start
4884 // inserting cast instructions as necessary...
4885 std::vector<Value*> Args;
4886 Args.reserve(NumActualArgs);
4888 AI = CS.arg_begin();
4889 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
4890 const Type *ParamTy = FT->getParamType(i);
4891 if ((*AI)->getType() == ParamTy) {
4892 Args.push_back(*AI);
4894 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
4899 // If the function takes more arguments than the call was taking, add them
4901 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
4902 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
4904 // If we are removing arguments to the function, emit an obnoxious warning...
4905 if (FT->getNumParams() < NumActualArgs)
4906 if (!FT->isVarArg()) {
4907 std::cerr << "WARNING: While resolving call to function '"
4908 << Callee->getName() << "' arguments were dropped!\n";
4910 // Add all of the arguments in their promoted form to the arg list...
4911 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
4912 const Type *PTy = getPromotedType((*AI)->getType());
4913 if (PTy != (*AI)->getType()) {
4914 // Must promote to pass through va_arg area!
4915 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
4916 InsertNewInstBefore(Cast, *Caller);
4917 Args.push_back(Cast);
4919 Args.push_back(*AI);
4924 if (FT->getReturnType() == Type::VoidTy)
4925 Caller->setName(""); // Void type should not have a name...
4928 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4929 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
4930 Args, Caller->getName(), Caller);
4931 cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
4933 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
4934 if (cast<CallInst>(Caller)->isTailCall())
4935 cast<CallInst>(NC)->setTailCall();
4936 cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
4939 // Insert a cast of the return type as necessary...
4941 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
4942 if (NV->getType() != Type::VoidTy) {
4943 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
4945 // If this is an invoke instruction, we should insert it after the first
4946 // non-phi, instruction in the normal successor block.
4947 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4948 BasicBlock::iterator I = II->getNormalDest()->begin();
4949 while (isa<PHINode>(I)) ++I;
4950 InsertNewInstBefore(NC, *I);
4952 // Otherwise, it's a call, just insert cast right after the call instr
4953 InsertNewInstBefore(NC, *Caller);
4955 AddUsersToWorkList(*Caller);
4957 NV = UndefValue::get(Caller->getType());
4961 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
4962 Caller->replaceAllUsesWith(NV);
4963 Caller->getParent()->getInstList().erase(Caller);
4964 removeFromWorkList(Caller);
4969 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
4970 // operator and they all are only used by the PHI, PHI together their
4971 // inputs, and do the operation once, to the result of the PHI.
4972 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
4973 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
4975 // Scan the instruction, looking for input operations that can be folded away.
4976 // If all input operands to the phi are the same instruction (e.g. a cast from
4977 // the same type or "+42") we can pull the operation through the PHI, reducing
4978 // code size and simplifying code.
4979 Constant *ConstantOp = 0;
4980 const Type *CastSrcTy = 0;
4981 if (isa<CastInst>(FirstInst)) {
4982 CastSrcTy = FirstInst->getOperand(0)->getType();
4983 } else if (isa<BinaryOperator>(FirstInst) || isa<ShiftInst>(FirstInst)) {
4984 // Can fold binop or shift if the RHS is a constant.
4985 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
4986 if (ConstantOp == 0) return 0;
4988 return 0; // Cannot fold this operation.
4991 // Check to see if all arguments are the same operation.
4992 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4993 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
4994 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
4995 if (!I->hasOneUse() || I->getOpcode() != FirstInst->getOpcode())
4998 if (I->getOperand(0)->getType() != CastSrcTy)
4999 return 0; // Cast operation must match.
5000 } else if (I->getOperand(1) != ConstantOp) {
5005 // Okay, they are all the same operation. Create a new PHI node of the
5006 // correct type, and PHI together all of the LHS's of the instructions.
5007 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
5008 PN.getName()+".in");
5009 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
5011 Value *InVal = FirstInst->getOperand(0);
5012 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
5014 // Add all operands to the new PHI.
5015 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
5016 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
5017 if (NewInVal != InVal)
5019 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
5024 // The new PHI unions all of the same values together. This is really
5025 // common, so we handle it intelligently here for compile-time speed.
5029 InsertNewInstBefore(NewPN, PN);
5033 // Insert and return the new operation.
5034 if (isa<CastInst>(FirstInst))
5035 return new CastInst(PhiVal, PN.getType());
5036 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
5037 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
5039 return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(),
5040 PhiVal, ConstantOp);
5043 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
5045 static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &PotentiallyDeadPHIs) {
5046 if (PN->use_empty()) return true;
5047 if (!PN->hasOneUse()) return false;
5049 // Remember this node, and if we find the cycle, return.
5050 if (!PotentiallyDeadPHIs.insert(PN).second)
5053 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
5054 return DeadPHICycle(PU, PotentiallyDeadPHIs);
5059 // PHINode simplification
5061 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
5062 if (Value *V = PN.hasConstantValue())
5063 return ReplaceInstUsesWith(PN, V);
5065 // If the only user of this instruction is a cast instruction, and all of the
5066 // incoming values are constants, change this PHI to merge together the casted
5069 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
5070 if (CI->getType() != PN.getType()) { // noop casts will be folded
5071 bool AllConstant = true;
5072 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
5073 if (!isa<Constant>(PN.getIncomingValue(i))) {
5074 AllConstant = false;
5078 // Make a new PHI with all casted values.
5079 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
5080 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
5081 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
5082 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
5083 PN.getIncomingBlock(i));
5086 // Update the cast instruction.
5087 CI->setOperand(0, New);
5088 WorkList.push_back(CI); // revisit the cast instruction to fold.
5089 WorkList.push_back(New); // Make sure to revisit the new Phi
5090 return &PN; // PN is now dead!
5094 // If all PHI operands are the same operation, pull them through the PHI,
5095 // reducing code size.
5096 if (isa<Instruction>(PN.getIncomingValue(0)) &&
5097 PN.getIncomingValue(0)->hasOneUse())
5098 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
5101 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
5102 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
5103 // PHI)... break the cycle.
5105 if (PHINode *PU = dyn_cast<PHINode>(PN.use_back())) {
5106 std::set<PHINode*> PotentiallyDeadPHIs;
5107 PotentiallyDeadPHIs.insert(&PN);
5108 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
5109 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
5115 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
5116 Instruction *InsertPoint,
5118 unsigned PS = IC->getTargetData().getPointerSize();
5119 const Type *VTy = V->getType();
5120 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
5121 // We must insert a cast to ensure we sign-extend.
5122 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
5123 V->getName()), *InsertPoint);
5124 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
5129 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
5130 Value *PtrOp = GEP.getOperand(0);
5131 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
5132 // If so, eliminate the noop.
5133 if (GEP.getNumOperands() == 1)
5134 return ReplaceInstUsesWith(GEP, PtrOp);
5136 if (isa<UndefValue>(GEP.getOperand(0)))
5137 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
5139 bool HasZeroPointerIndex = false;
5140 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
5141 HasZeroPointerIndex = C->isNullValue();
5143 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
5144 return ReplaceInstUsesWith(GEP, PtrOp);
5146 // Eliminate unneeded casts for indices.
5147 bool MadeChange = false;
5148 gep_type_iterator GTI = gep_type_begin(GEP);
5149 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
5150 if (isa<SequentialType>(*GTI)) {
5151 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
5152 Value *Src = CI->getOperand(0);
5153 const Type *SrcTy = Src->getType();
5154 const Type *DestTy = CI->getType();
5155 if (Src->getType()->isInteger()) {
5156 if (SrcTy->getPrimitiveSizeInBits() ==
5157 DestTy->getPrimitiveSizeInBits()) {
5158 // We can always eliminate a cast from ulong or long to the other.
5159 // We can always eliminate a cast from uint to int or the other on
5160 // 32-bit pointer platforms.
5161 if (DestTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()){
5163 GEP.setOperand(i, Src);
5165 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
5166 SrcTy->getPrimitiveSize() == 4) {
5167 // We can always eliminate a cast from int to [u]long. We can
5168 // eliminate a cast from uint to [u]long iff the target is a 32-bit
5170 if (SrcTy->isSigned() ||
5171 SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
5173 GEP.setOperand(i, Src);
5178 // If we are using a wider index than needed for this platform, shrink it
5179 // to what we need. If the incoming value needs a cast instruction,
5180 // insert it. This explicit cast can make subsequent optimizations more
5182 Value *Op = GEP.getOperand(i);
5183 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
5184 if (Constant *C = dyn_cast<Constant>(Op)) {
5185 GEP.setOperand(i, ConstantExpr::getCast(C,
5186 TD->getIntPtrType()->getSignedVersion()));
5189 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
5190 Op->getName()), GEP);
5191 GEP.setOperand(i, Op);
5195 // If this is a constant idx, make sure to canonicalize it to be a signed
5196 // operand, otherwise CSE and other optimizations are pessimized.
5197 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
5198 GEP.setOperand(i, ConstantExpr::getCast(CUI,
5199 CUI->getType()->getSignedVersion()));
5203 if (MadeChange) return &GEP;
5205 // Combine Indices - If the source pointer to this getelementptr instruction
5206 // is a getelementptr instruction, combine the indices of the two
5207 // getelementptr instructions into a single instruction.
5209 std::vector<Value*> SrcGEPOperands;
5210 if (User *Src = dyn_castGetElementPtr(PtrOp))
5211 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
5213 if (!SrcGEPOperands.empty()) {
5214 // Note that if our source is a gep chain itself that we wait for that
5215 // chain to be resolved before we perform this transformation. This
5216 // avoids us creating a TON of code in some cases.
5218 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
5219 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
5220 return 0; // Wait until our source is folded to completion.
5222 std::vector<Value *> Indices;
5224 // Find out whether the last index in the source GEP is a sequential idx.
5225 bool EndsWithSequential = false;
5226 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
5227 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
5228 EndsWithSequential = !isa<StructType>(*I);
5230 // Can we combine the two pointer arithmetics offsets?
5231 if (EndsWithSequential) {
5232 // Replace: gep (gep %P, long B), long A, ...
5233 // With: T = long A+B; gep %P, T, ...
5235 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
5236 if (SO1 == Constant::getNullValue(SO1->getType())) {
5238 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
5241 // If they aren't the same type, convert both to an integer of the
5242 // target's pointer size.
5243 if (SO1->getType() != GO1->getType()) {
5244 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
5245 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
5246 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
5247 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
5249 unsigned PS = TD->getPointerSize();
5250 if (SO1->getType()->getPrimitiveSize() == PS) {
5251 // Convert GO1 to SO1's type.
5252 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
5254 } else if (GO1->getType()->getPrimitiveSize() == PS) {
5255 // Convert SO1 to GO1's type.
5256 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
5258 const Type *PT = TD->getIntPtrType();
5259 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
5260 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
5264 if (isa<Constant>(SO1) && isa<Constant>(GO1))
5265 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
5267 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
5268 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
5272 // Recycle the GEP we already have if possible.
5273 if (SrcGEPOperands.size() == 2) {
5274 GEP.setOperand(0, SrcGEPOperands[0]);
5275 GEP.setOperand(1, Sum);
5278 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
5279 SrcGEPOperands.end()-1);
5280 Indices.push_back(Sum);
5281 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
5283 } else if (isa<Constant>(*GEP.idx_begin()) &&
5284 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
5285 SrcGEPOperands.size() != 1) {
5286 // Otherwise we can do the fold if the first index of the GEP is a zero
5287 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
5288 SrcGEPOperands.end());
5289 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
5292 if (!Indices.empty())
5293 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
5295 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
5296 // GEP of global variable. If all of the indices for this GEP are
5297 // constants, we can promote this to a constexpr instead of an instruction.
5299 // Scan for nonconstants...
5300 std::vector<Constant*> Indices;
5301 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
5302 for (; I != E && isa<Constant>(*I); ++I)
5303 Indices.push_back(cast<Constant>(*I));
5305 if (I == E) { // If they are all constants...
5306 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
5308 // Replace all uses of the GEP with the new constexpr...
5309 return ReplaceInstUsesWith(GEP, CE);
5311 } else if (Value *X = isCast(PtrOp)) { // Is the operand a cast?
5312 if (!isa<PointerType>(X->getType())) {
5313 // Not interesting. Source pointer must be a cast from pointer.
5314 } else if (HasZeroPointerIndex) {
5315 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
5316 // into : GEP [10 x ubyte]* X, long 0, ...
5318 // This occurs when the program declares an array extern like "int X[];"
5320 const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
5321 const PointerType *XTy = cast<PointerType>(X->getType());
5322 if (const ArrayType *XATy =
5323 dyn_cast<ArrayType>(XTy->getElementType()))
5324 if (const ArrayType *CATy =
5325 dyn_cast<ArrayType>(CPTy->getElementType()))
5326 if (CATy->getElementType() == XATy->getElementType()) {
5327 // At this point, we know that the cast source type is a pointer
5328 // to an array of the same type as the destination pointer
5329 // array. Because the array type is never stepped over (there
5330 // is a leading zero) we can fold the cast into this GEP.
5331 GEP.setOperand(0, X);
5334 } else if (GEP.getNumOperands() == 2) {
5335 // Transform things like:
5336 // %t = getelementptr ubyte* cast ([2 x int]* %str to uint*), uint %V
5337 // into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast
5338 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
5339 const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
5340 if (isa<ArrayType>(SrcElTy) &&
5341 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
5342 TD->getTypeSize(ResElTy)) {
5343 Value *V = InsertNewInstBefore(
5344 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
5345 GEP.getOperand(1), GEP.getName()), GEP);
5346 return new CastInst(V, GEP.getType());
5349 // Transform things like:
5350 // getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp
5351 // (where tmp = 8*tmp2) into:
5352 // getelementptr [100 x double]* %arr, int 0, int %tmp.2
5354 if (isa<ArrayType>(SrcElTy) &&
5355 (ResElTy == Type::SByteTy || ResElTy == Type::UByteTy)) {
5356 uint64_t ArrayEltSize =
5357 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType());
5359 // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
5360 // allow either a mul, shift, or constant here.
5362 ConstantInt *Scale = 0;
5363 if (ArrayEltSize == 1) {
5364 NewIdx = GEP.getOperand(1);
5365 Scale = ConstantInt::get(NewIdx->getType(), 1);
5366 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
5367 NewIdx = ConstantInt::get(CI->getType(), 1);
5369 } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
5370 if (Inst->getOpcode() == Instruction::Shl &&
5371 isa<ConstantInt>(Inst->getOperand(1))) {
5372 unsigned ShAmt =cast<ConstantUInt>(Inst->getOperand(1))->getValue();
5373 if (Inst->getType()->isSigned())
5374 Scale = ConstantSInt::get(Inst->getType(), 1ULL << ShAmt);
5376 Scale = ConstantUInt::get(Inst->getType(), 1ULL << ShAmt);
5377 NewIdx = Inst->getOperand(0);
5378 } else if (Inst->getOpcode() == Instruction::Mul &&
5379 isa<ConstantInt>(Inst->getOperand(1))) {
5380 Scale = cast<ConstantInt>(Inst->getOperand(1));
5381 NewIdx = Inst->getOperand(0);
5385 // If the index will be to exactly the right offset with the scale taken
5386 // out, perform the transformation.
5387 if (Scale && Scale->getRawValue() % ArrayEltSize == 0) {
5388 if (ConstantSInt *C = dyn_cast<ConstantSInt>(Scale))
5389 Scale = ConstantSInt::get(C->getType(),
5390 (int64_t)C->getRawValue() /
5391 (int64_t)ArrayEltSize);
5393 Scale = ConstantUInt::get(Scale->getType(),
5394 Scale->getRawValue() / ArrayEltSize);
5395 if (Scale->getRawValue() != 1) {
5396 Constant *C = ConstantExpr::getCast(Scale, NewIdx->getType());
5397 Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale");
5398 NewIdx = InsertNewInstBefore(Sc, GEP);
5401 // Insert the new GEP instruction.
5403 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
5404 NewIdx, GEP.getName());
5405 Idx = InsertNewInstBefore(Idx, GEP);
5406 return new CastInst(Idx, GEP.getType());
5415 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
5416 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
5417 if (AI.isArrayAllocation()) // Check C != 1
5418 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
5419 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
5420 AllocationInst *New = 0;
5422 // Create and insert the replacement instruction...
5423 if (isa<MallocInst>(AI))
5424 New = new MallocInst(NewTy, 0, AI.getAlignment(), AI.getName());
5426 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
5427 New = new AllocaInst(NewTy, 0, AI.getAlignment(), AI.getName());
5430 InsertNewInstBefore(New, AI);
5432 // Scan to the end of the allocation instructions, to skip over a block of
5433 // allocas if possible...
5435 BasicBlock::iterator It = New;
5436 while (isa<AllocationInst>(*It)) ++It;
5438 // Now that I is pointing to the first non-allocation-inst in the block,
5439 // insert our getelementptr instruction...
5441 Value *NullIdx = Constant::getNullValue(Type::IntTy);
5442 Value *V = new GetElementPtrInst(New, NullIdx, NullIdx,
5443 New->getName()+".sub", It);
5445 // Now make everything use the getelementptr instead of the original
5447 return ReplaceInstUsesWith(AI, V);
5448 } else if (isa<UndefValue>(AI.getArraySize())) {
5449 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5452 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
5453 // Note that we only do this for alloca's, because malloc should allocate and
5454 // return a unique pointer, even for a zero byte allocation.
5455 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
5456 TD->getTypeSize(AI.getAllocatedType()) == 0)
5457 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5462 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
5463 Value *Op = FI.getOperand(0);
5465 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
5466 if (CastInst *CI = dyn_cast<CastInst>(Op))
5467 if (isa<PointerType>(CI->getOperand(0)->getType())) {
5468 FI.setOperand(0, CI->getOperand(0));
5472 // free undef -> unreachable.
5473 if (isa<UndefValue>(Op)) {
5474 // Insert a new store to null because we cannot modify the CFG here.
5475 new StoreInst(ConstantBool::True,
5476 UndefValue::get(PointerType::get(Type::BoolTy)), &FI);
5477 return EraseInstFromFunction(FI);
5480 // If we have 'free null' delete the instruction. This can happen in stl code
5481 // when lots of inlining happens.
5482 if (isa<ConstantPointerNull>(Op))
5483 return EraseInstFromFunction(FI);
5489 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
5490 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
5491 User *CI = cast<User>(LI.getOperand(0));
5492 Value *CastOp = CI->getOperand(0);
5494 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5495 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5496 const Type *SrcPTy = SrcTy->getElementType();
5498 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5499 // If the source is an array, the code below will not succeed. Check to
5500 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5502 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5503 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5504 if (ASrcTy->getNumElements() != 0) {
5505 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5506 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5507 SrcTy = cast<PointerType>(CastOp->getType());
5508 SrcPTy = SrcTy->getElementType();
5511 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5512 // Do not allow turning this into a load of an integer, which is then
5513 // casted to a pointer, this pessimizes pointer analysis a lot.
5514 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
5515 IC.getTargetData().getTypeSize(SrcPTy) ==
5516 IC.getTargetData().getTypeSize(DestPTy)) {
5518 // Okay, we are casting from one integer or pointer type to another of
5519 // the same size. Instead of casting the pointer before the load, cast
5520 // the result of the loaded value.
5521 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
5523 LI.isVolatile()),LI);
5524 // Now cast the result of the load.
5525 return new CastInst(NewLoad, LI.getType());
5532 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
5533 /// from this value cannot trap. If it is not obviously safe to load from the
5534 /// specified pointer, we do a quick local scan of the basic block containing
5535 /// ScanFrom, to determine if the address is already accessed.
5536 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
5537 // If it is an alloca or global variable, it is always safe to load from.
5538 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
5540 // Otherwise, be a little bit agressive by scanning the local block where we
5541 // want to check to see if the pointer is already being loaded or stored
5542 // from/to. If so, the previous load or store would have already trapped,
5543 // so there is no harm doing an extra load (also, CSE will later eliminate
5544 // the load entirely).
5545 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
5550 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
5551 if (LI->getOperand(0) == V) return true;
5552 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
5553 if (SI->getOperand(1) == V) return true;
5559 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
5560 Value *Op = LI.getOperand(0);
5562 // load (cast X) --> cast (load X) iff safe
5563 if (CastInst *CI = dyn_cast<CastInst>(Op))
5564 if (Instruction *Res = InstCombineLoadCast(*this, LI))
5567 // None of the following transforms are legal for volatile loads.
5568 if (LI.isVolatile()) return 0;
5570 if (&LI.getParent()->front() != &LI) {
5571 BasicBlock::iterator BBI = &LI; --BBI;
5572 // If the instruction immediately before this is a store to the same
5573 // address, do a simple form of store->load forwarding.
5574 if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
5575 if (SI->getOperand(1) == LI.getOperand(0))
5576 return ReplaceInstUsesWith(LI, SI->getOperand(0));
5577 if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
5578 if (LIB->getOperand(0) == LI.getOperand(0))
5579 return ReplaceInstUsesWith(LI, LIB);
5582 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
5583 if (isa<ConstantPointerNull>(GEPI->getOperand(0)) ||
5584 isa<UndefValue>(GEPI->getOperand(0))) {
5585 // Insert a new store to null instruction before the load to indicate
5586 // that this code is not reachable. We do this instead of inserting
5587 // an unreachable instruction directly because we cannot modify the
5589 new StoreInst(UndefValue::get(LI.getType()),
5590 Constant::getNullValue(Op->getType()), &LI);
5591 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5594 if (Constant *C = dyn_cast<Constant>(Op)) {
5595 // load null/undef -> undef
5596 if ((C->isNullValue() || isa<UndefValue>(C))) {
5597 // Insert a new store to null instruction before the load to indicate that
5598 // this code is not reachable. We do this instead of inserting an
5599 // unreachable instruction directly because we cannot modify the CFG.
5600 new StoreInst(UndefValue::get(LI.getType()),
5601 Constant::getNullValue(Op->getType()), &LI);
5602 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5605 // Instcombine load (constant global) into the value loaded.
5606 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
5607 if (GV->isConstant() && !GV->isExternal())
5608 return ReplaceInstUsesWith(LI, GV->getInitializer());
5610 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
5611 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
5612 if (CE->getOpcode() == Instruction::GetElementPtr) {
5613 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
5614 if (GV->isConstant() && !GV->isExternal())
5616 ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
5617 return ReplaceInstUsesWith(LI, V);
5618 if (CE->getOperand(0)->isNullValue()) {
5619 // Insert a new store to null instruction before the load to indicate
5620 // that this code is not reachable. We do this instead of inserting
5621 // an unreachable instruction directly because we cannot modify the
5623 new StoreInst(UndefValue::get(LI.getType()),
5624 Constant::getNullValue(Op->getType()), &LI);
5625 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5628 } else if (CE->getOpcode() == Instruction::Cast) {
5629 if (Instruction *Res = InstCombineLoadCast(*this, LI))
5634 if (Op->hasOneUse()) {
5635 // Change select and PHI nodes to select values instead of addresses: this
5636 // helps alias analysis out a lot, allows many others simplifications, and
5637 // exposes redundancy in the code.
5639 // Note that we cannot do the transformation unless we know that the
5640 // introduced loads cannot trap! Something like this is valid as long as
5641 // the condition is always false: load (select bool %C, int* null, int* %G),
5642 // but it would not be valid if we transformed it to load from null
5645 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
5646 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
5647 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
5648 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
5649 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
5650 SI->getOperand(1)->getName()+".val"), LI);
5651 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
5652 SI->getOperand(2)->getName()+".val"), LI);
5653 return new SelectInst(SI->getCondition(), V1, V2);
5656 // load (select (cond, null, P)) -> load P
5657 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
5658 if (C->isNullValue()) {
5659 LI.setOperand(0, SI->getOperand(2));
5663 // load (select (cond, P, null)) -> load P
5664 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
5665 if (C->isNullValue()) {
5666 LI.setOperand(0, SI->getOperand(1));
5670 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
5671 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
5672 bool Safe = PN->getParent() == LI.getParent();
5674 // Scan all of the instructions between the PHI and the load to make
5675 // sure there are no instructions that might possibly alter the value
5676 // loaded from the PHI.
5678 BasicBlock::iterator I = &LI;
5679 for (--I; !isa<PHINode>(I); --I)
5680 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
5686 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
5687 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
5688 PN->getIncomingBlock(i)->getTerminator()))
5693 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
5694 InsertNewInstBefore(NewPN, *PN);
5695 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
5697 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
5698 BasicBlock *BB = PN->getIncomingBlock(i);
5699 Value *&TheLoad = LoadMap[BB];
5701 Value *InVal = PN->getIncomingValue(i);
5702 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
5703 InVal->getName()+".val"),
5704 *BB->getTerminator());
5706 NewPN->addIncoming(TheLoad, BB);
5708 return ReplaceInstUsesWith(LI, NewPN);
5715 /// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store (cast V), P'
5717 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
5718 User *CI = cast<User>(SI.getOperand(1));
5719 Value *CastOp = CI->getOperand(0);
5721 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5722 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5723 const Type *SrcPTy = SrcTy->getElementType();
5725 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5726 // If the source is an array, the code below will not succeed. Check to
5727 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5729 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5730 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5731 if (ASrcTy->getNumElements() != 0) {
5732 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5733 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5734 SrcTy = cast<PointerType>(CastOp->getType());
5735 SrcPTy = SrcTy->getElementType();
5738 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5739 IC.getTargetData().getTypeSize(SrcPTy) ==
5740 IC.getTargetData().getTypeSize(DestPTy)) {
5742 // Okay, we are casting from one integer or pointer type to another of
5743 // the same size. Instead of casting the pointer before the store, cast
5744 // the value to be stored.
5746 if (Constant *C = dyn_cast<Constant>(SI.getOperand(0)))
5747 NewCast = ConstantExpr::getCast(C, SrcPTy);
5749 NewCast = IC.InsertNewInstBefore(new CastInst(SI.getOperand(0),
5751 SI.getOperand(0)->getName()+".c"), SI);
5753 return new StoreInst(NewCast, CastOp);
5760 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
5761 Value *Val = SI.getOperand(0);
5762 Value *Ptr = SI.getOperand(1);
5764 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
5765 removeFromWorkList(&SI);
5766 SI.eraseFromParent();
5771 if (SI.isVolatile()) return 0; // Don't hack volatile loads.
5773 // store X, null -> turns into 'unreachable' in SimplifyCFG
5774 if (isa<ConstantPointerNull>(Ptr)) {
5775 if (!isa<UndefValue>(Val)) {
5776 SI.setOperand(0, UndefValue::get(Val->getType()));
5777 if (Instruction *U = dyn_cast<Instruction>(Val))
5778 WorkList.push_back(U); // Dropped a use.
5781 return 0; // Do not modify these!
5784 // store undef, Ptr -> noop
5785 if (isa<UndefValue>(Val)) {
5786 removeFromWorkList(&SI);
5787 SI.eraseFromParent();
5792 // If the pointer destination is a cast, see if we can fold the cast into the
5794 if (CastInst *CI = dyn_cast<CastInst>(Ptr))
5795 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5797 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
5798 if (CE->getOpcode() == Instruction::Cast)
5799 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5803 // If this store is the last instruction in the basic block, and if the block
5804 // ends with an unconditional branch, try to move it to the successor block.
5805 BasicBlock::iterator BBI = &SI; ++BBI;
5806 if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
5807 if (BI->isUnconditional()) {
5808 // Check to see if the successor block has exactly two incoming edges. If
5809 // so, see if the other predecessor contains a store to the same location.
5810 // if so, insert a PHI node (if needed) and move the stores down.
5811 BasicBlock *Dest = BI->getSuccessor(0);
5813 pred_iterator PI = pred_begin(Dest);
5814 BasicBlock *Other = 0;
5815 if (*PI != BI->getParent())
5818 if (PI != pred_end(Dest)) {
5819 if (*PI != BI->getParent())
5824 if (++PI != pred_end(Dest))
5827 if (Other) { // If only one other pred...
5828 BBI = Other->getTerminator();
5829 // Make sure this other block ends in an unconditional branch and that
5830 // there is an instruction before the branch.
5831 if (isa<BranchInst>(BBI) && cast<BranchInst>(BBI)->isUnconditional() &&
5832 BBI != Other->begin()) {
5834 StoreInst *OtherStore = dyn_cast<StoreInst>(BBI);
5836 // If this instruction is a store to the same location.
5837 if (OtherStore && OtherStore->getOperand(1) == SI.getOperand(1)) {
5838 // Okay, we know we can perform this transformation. Insert a PHI
5839 // node now if we need it.
5840 Value *MergedVal = OtherStore->getOperand(0);
5841 if (MergedVal != SI.getOperand(0)) {
5842 PHINode *PN = new PHINode(MergedVal->getType(), "storemerge");
5843 PN->reserveOperandSpace(2);
5844 PN->addIncoming(SI.getOperand(0), SI.getParent());
5845 PN->addIncoming(OtherStore->getOperand(0), Other);
5846 MergedVal = InsertNewInstBefore(PN, Dest->front());
5849 // Advance to a place where it is safe to insert the new store and
5851 BBI = Dest->begin();
5852 while (isa<PHINode>(BBI)) ++BBI;
5853 InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
5854 OtherStore->isVolatile()), *BBI);
5856 // Nuke the old stores.
5857 removeFromWorkList(&SI);
5858 removeFromWorkList(OtherStore);
5859 SI.eraseFromParent();
5860 OtherStore->eraseFromParent();
5872 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
5873 // Change br (not X), label True, label False to: br X, label False, True
5875 BasicBlock *TrueDest;
5876 BasicBlock *FalseDest;
5877 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
5878 !isa<Constant>(X)) {
5879 // Swap Destinations and condition...
5881 BI.setSuccessor(0, FalseDest);
5882 BI.setSuccessor(1, TrueDest);
5886 // Cannonicalize setne -> seteq
5887 Instruction::BinaryOps Op; Value *Y;
5888 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
5889 TrueDest, FalseDest)))
5890 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
5891 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
5892 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
5893 std::string Name = I->getName(); I->setName("");
5894 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
5895 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
5896 // Swap Destinations and condition...
5897 BI.setCondition(NewSCC);
5898 BI.setSuccessor(0, FalseDest);
5899 BI.setSuccessor(1, TrueDest);
5900 removeFromWorkList(I);
5901 I->getParent()->getInstList().erase(I);
5902 WorkList.push_back(cast<Instruction>(NewSCC));
5909 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
5910 Value *Cond = SI.getCondition();
5911 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
5912 if (I->getOpcode() == Instruction::Add)
5913 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
5914 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
5915 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
5916 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
5918 SI.setOperand(0, I->getOperand(0));
5919 WorkList.push_back(I);
5926 Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
5927 if (ConstantAggregateZero *C =
5928 dyn_cast<ConstantAggregateZero>(EI.getOperand(0))) {
5929 // If packed val is constant 0, replace extract with scalar 0
5930 const Type *Ty = cast<PackedType>(C->getType())->getElementType();
5931 EI.replaceAllUsesWith(Constant::getNullValue(Ty));
5932 return ReplaceInstUsesWith(EI, Constant::getNullValue(Ty));
5934 if (ConstantPacked *C = dyn_cast<ConstantPacked>(EI.getOperand(0))) {
5935 // If packed val is constant with uniform operands, replace EI
5936 // with that operand
5937 Constant *op0 = cast<Constant>(C->getOperand(0));
5938 for (unsigned i = 1; i < C->getNumOperands(); ++i)
5939 if (C->getOperand(i) != op0) return 0;
5940 return ReplaceInstUsesWith(EI, op0);
5942 if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0)))
5943 if (I->hasOneUse()) {
5944 // Push extractelement into predecessor operation if legal and
5945 // profitable to do so
5946 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
5947 if (!isa<Constant>(BO->getOperand(0)) &&
5948 !isa<Constant>(BO->getOperand(1)))
5950 ExtractElementInst *newEI0 =
5951 new ExtractElementInst(BO->getOperand(0), EI.getOperand(1),
5953 ExtractElementInst *newEI1 =
5954 new ExtractElementInst(BO->getOperand(1), EI.getOperand(1),
5956 InsertNewInstBefore(newEI0, EI);
5957 InsertNewInstBefore(newEI1, EI);
5958 return BinaryOperator::create(BO->getOpcode(), newEI0, newEI1);
5960 switch(I->getOpcode()) {
5961 case Instruction::Load: {
5962 Value *Ptr = InsertCastBefore(I->getOperand(0),
5963 PointerType::get(EI.getType()), EI);
5964 GetElementPtrInst *GEP =
5965 new GetElementPtrInst(Ptr, EI.getOperand(1),
5966 I->getName() + ".gep");
5967 InsertNewInstBefore(GEP, EI);
5968 return new LoadInst(GEP);
5978 void InstCombiner::removeFromWorkList(Instruction *I) {
5979 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
5984 /// TryToSinkInstruction - Try to move the specified instruction from its
5985 /// current block into the beginning of DestBlock, which can only happen if it's
5986 /// safe to move the instruction past all of the instructions between it and the
5987 /// end of its block.
5988 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
5989 assert(I->hasOneUse() && "Invariants didn't hold!");
5991 // Cannot move control-flow-involving, volatile loads, vaarg, etc.
5992 if (isa<PHINode>(I) || I->mayWriteToMemory()) return false;
5994 // Do not sink alloca instructions out of the entry block.
5995 if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front())
5998 // We can only sink load instructions if there is nothing between the load and
5999 // the end of block that could change the value.
6000 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
6001 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
6003 if (Scan->mayWriteToMemory())
6007 BasicBlock::iterator InsertPos = DestBlock->begin();
6008 while (isa<PHINode>(InsertPos)) ++InsertPos;
6010 I->moveBefore(InsertPos);
6015 bool InstCombiner::runOnFunction(Function &F) {
6016 bool Changed = false;
6017 TD = &getAnalysis<TargetData>();
6020 // Populate the worklist with the reachable instructions.
6021 std::set<BasicBlock*> Visited;
6022 for (df_ext_iterator<BasicBlock*> BB = df_ext_begin(&F.front(), Visited),
6023 E = df_ext_end(&F.front(), Visited); BB != E; ++BB)
6024 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
6025 WorkList.push_back(I);
6027 // Do a quick scan over the function. If we find any blocks that are
6028 // unreachable, remove any instructions inside of them. This prevents
6029 // the instcombine code from having to deal with some bad special cases.
6030 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
6031 if (!Visited.count(BB)) {
6032 Instruction *Term = BB->getTerminator();
6033 while (Term != BB->begin()) { // Remove instrs bottom-up
6034 BasicBlock::iterator I = Term; --I;
6036 DEBUG(std::cerr << "IC: DCE: " << *I);
6039 if (!I->use_empty())
6040 I->replaceAllUsesWith(UndefValue::get(I->getType()));
6041 I->eraseFromParent();
6046 while (!WorkList.empty()) {
6047 Instruction *I = WorkList.back(); // Get an instruction from the worklist
6048 WorkList.pop_back();
6050 // Check to see if we can DCE or ConstantPropagate the instruction...
6051 // Check to see if we can DIE the instruction...
6052 if (isInstructionTriviallyDead(I)) {
6053 // Add operands to the worklist...
6054 if (I->getNumOperands() < 4)
6055 AddUsesToWorkList(*I);
6058 DEBUG(std::cerr << "IC: DCE: " << *I);
6060 I->eraseFromParent();
6061 removeFromWorkList(I);
6065 // Instruction isn't dead, see if we can constant propagate it...
6066 if (Constant *C = ConstantFoldInstruction(I)) {
6067 Value* Ptr = I->getOperand(0);
6068 if (isa<GetElementPtrInst>(I) &&
6069 cast<Constant>(Ptr)->isNullValue() &&
6070 !isa<ConstantPointerNull>(C) &&
6071 cast<PointerType>(Ptr->getType())->getElementType()->isSized()) {
6072 // If this is a constant expr gep that is effectively computing an
6073 // "offsetof", fold it into 'cast int X to T*' instead of 'gep 0, 0, 12'
6074 bool isFoldableGEP = true;
6075 for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
6076 if (!isa<ConstantInt>(I->getOperand(i)))
6077 isFoldableGEP = false;
6078 if (isFoldableGEP) {
6079 uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
6080 std::vector<Value*>(I->op_begin()+1, I->op_end()));
6081 C = ConstantUInt::get(Type::ULongTy, Offset);
6082 C = ConstantExpr::getCast(C, TD->getIntPtrType());
6083 C = ConstantExpr::getCast(C, I->getType());
6087 DEBUG(std::cerr << "IC: ConstFold to: " << *C << " from: " << *I);
6089 // Add operands to the worklist...
6090 AddUsesToWorkList(*I);
6091 ReplaceInstUsesWith(*I, C);
6094 I->getParent()->getInstList().erase(I);
6095 removeFromWorkList(I);
6099 // See if we can trivially sink this instruction to a successor basic block.
6100 if (I->hasOneUse()) {
6101 BasicBlock *BB = I->getParent();
6102 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
6103 if (UserParent != BB) {
6104 bool UserIsSuccessor = false;
6105 // See if the user is one of our successors.
6106 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
6107 if (*SI == UserParent) {
6108 UserIsSuccessor = true;
6112 // If the user is one of our immediate successors, and if that successor
6113 // only has us as a predecessors (we'd have to split the critical edge
6114 // otherwise), we can keep going.
6115 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
6116 next(pred_begin(UserParent)) == pred_end(UserParent))
6117 // Okay, the CFG is simple enough, try to sink this instruction.
6118 Changed |= TryToSinkInstruction(I, UserParent);
6122 // Now that we have an instruction, try combining it to simplify it...
6123 if (Instruction *Result = visit(*I)) {
6125 // Should we replace the old instruction with a new one?
6127 DEBUG(std::cerr << "IC: Old = " << *I
6128 << " New = " << *Result);
6130 // Everything uses the new instruction now.
6131 I->replaceAllUsesWith(Result);
6133 // Push the new instruction and any users onto the worklist.
6134 WorkList.push_back(Result);
6135 AddUsersToWorkList(*Result);
6137 // Move the name to the new instruction first...
6138 std::string OldName = I->getName(); I->setName("");
6139 Result->setName(OldName);
6141 // Insert the new instruction into the basic block...
6142 BasicBlock *InstParent = I->getParent();
6143 BasicBlock::iterator InsertPos = I;
6145 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
6146 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
6149 InstParent->getInstList().insert(InsertPos, Result);
6151 // Make sure that we reprocess all operands now that we reduced their
6153 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
6154 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
6155 WorkList.push_back(OpI);
6157 // Instructions can end up on the worklist more than once. Make sure
6158 // we do not process an instruction that has been deleted.
6159 removeFromWorkList(I);
6161 // Erase the old instruction.
6162 InstParent->getInstList().erase(I);
6164 DEBUG(std::cerr << "IC: MOD = " << *I);
6166 // If the instruction was modified, it's possible that it is now dead.
6167 // if so, remove it.
6168 if (isInstructionTriviallyDead(I)) {
6169 // Make sure we process all operands now that we are reducing their
6171 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
6172 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
6173 WorkList.push_back(OpI);
6175 // Instructions may end up in the worklist more than once. Erase all
6176 // occurrences of this instruction.
6177 removeFromWorkList(I);
6178 I->eraseFromParent();
6180 WorkList.push_back(Result);
6181 AddUsersToWorkList(*Result);
6191 FunctionPass *llvm::createInstructionCombiningPass() {
6192 return new InstCombiner();