1 //===- InstructionCombining.cpp - Combine multiple instructions -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // InstructionCombining - Combine instructions to form fewer, simple
11 // instructions. This pass does not modify the CFG This pass is where algebraic
12 // simplification happens.
14 // This pass combines things like:
20 // This is a simple worklist driven algorithm.
22 // This pass guarantees that the following canonicalizations are performed on
24 // 1. If a binary operator has a constant operand, it is moved to the RHS
25 // 2. Bitwise operators with constant operands are always grouped so that
26 // shifts are performed first, then or's, then and's, then xor's.
27 // 3. SetCC instructions are converted from <,>,<=,>= to ==,!= if possible
28 // 4. All SetCC instructions on boolean values are replaced with logical ops
29 // 5. add X, X is represented as (X*2) => (X << 1)
30 // 6. Multiplies with a power-of-two constant argument are transformed into
34 //===----------------------------------------------------------------------===//
36 #define DEBUG_TYPE "instcombine"
37 #include "llvm/Transforms/Scalar.h"
38 #include "llvm/IntrinsicInst.h"
39 #include "llvm/Pass.h"
40 #include "llvm/DerivedTypes.h"
41 #include "llvm/GlobalVariable.h"
42 #include "llvm/Target/TargetData.h"
43 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
44 #include "llvm/Transforms/Utils/Local.h"
45 #include "llvm/Support/CallSite.h"
46 #include "llvm/Support/Debug.h"
47 #include "llvm/Support/GetElementPtrTypeIterator.h"
48 #include "llvm/Support/InstVisitor.h"
49 #include "llvm/Support/MathExtras.h"
50 #include "llvm/Support/PatternMatch.h"
51 #include "llvm/ADT/DepthFirstIterator.h"
52 #include "llvm/ADT/Statistic.h"
53 #include "llvm/ADT/STLExtras.h"
56 using namespace llvm::PatternMatch;
59 Statistic<> NumCombined ("instcombine", "Number of insts combined");
60 Statistic<> NumConstProp("instcombine", "Number of constant folds");
61 Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
62 Statistic<> NumSunkInst ("instcombine", "Number of instructions sunk");
64 class InstCombiner : public FunctionPass,
65 public InstVisitor<InstCombiner, Instruction*> {
66 // Worklist of all of the instructions that need to be simplified.
67 std::vector<Instruction*> WorkList;
70 /// AddUsersToWorkList - When an instruction is simplified, add all users of
71 /// the instruction to the work lists because they might get more simplified
74 void AddUsersToWorkList(Instruction &I) {
75 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
77 WorkList.push_back(cast<Instruction>(*UI));
80 /// AddUsesToWorkList - When an instruction is simplified, add operands to
81 /// the work lists because they might get more simplified now.
83 void AddUsesToWorkList(Instruction &I) {
84 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
85 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
86 WorkList.push_back(Op);
89 // removeFromWorkList - remove all instances of I from the worklist.
90 void removeFromWorkList(Instruction *I);
92 virtual bool runOnFunction(Function &F);
94 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
95 AU.addRequired<TargetData>();
99 TargetData &getTargetData() const { return *TD; }
101 // Visitation implementation - Implement instruction combining for different
102 // instruction types. The semantics are as follows:
104 // null - No change was made
105 // I - Change was made, I is still valid, I may be dead though
106 // otherwise - Change was made, replace I with returned instruction
108 Instruction *visitAdd(BinaryOperator &I);
109 Instruction *visitSub(BinaryOperator &I);
110 Instruction *visitMul(BinaryOperator &I);
111 Instruction *visitDiv(BinaryOperator &I);
112 Instruction *visitRem(BinaryOperator &I);
113 Instruction *visitAnd(BinaryOperator &I);
114 Instruction *visitOr (BinaryOperator &I);
115 Instruction *visitXor(BinaryOperator &I);
116 Instruction *visitSetCondInst(SetCondInst &I);
117 Instruction *visitSetCondInstWithCastAndCast(SetCondInst &SCI);
119 Instruction *FoldGEPSetCC(User *GEPLHS, Value *RHS,
120 Instruction::BinaryOps Cond, Instruction &I);
121 Instruction *visitShiftInst(ShiftInst &I);
122 Instruction *visitCastInst(CastInst &CI);
123 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
125 Instruction *visitSelectInst(SelectInst &CI);
126 Instruction *visitCallInst(CallInst &CI);
127 Instruction *visitInvokeInst(InvokeInst &II);
128 Instruction *visitPHINode(PHINode &PN);
129 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
130 Instruction *visitAllocationInst(AllocationInst &AI);
131 Instruction *visitFreeInst(FreeInst &FI);
132 Instruction *visitLoadInst(LoadInst &LI);
133 Instruction *visitStoreInst(StoreInst &SI);
134 Instruction *visitBranchInst(BranchInst &BI);
135 Instruction *visitSwitchInst(SwitchInst &SI);
137 // visitInstruction - Specify what to return for unhandled instructions...
138 Instruction *visitInstruction(Instruction &I) { return 0; }
141 Instruction *visitCallSite(CallSite CS);
142 bool transformConstExprCastCall(CallSite CS);
145 // InsertNewInstBefore - insert an instruction New before instruction Old
146 // in the program. Add the new instruction to the worklist.
148 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
149 assert(New && New->getParent() == 0 &&
150 "New instruction already inserted into a basic block!");
151 BasicBlock *BB = Old.getParent();
152 BB->getInstList().insert(&Old, New); // Insert inst
153 WorkList.push_back(New); // Add to worklist
157 /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
158 /// This also adds the cast to the worklist. Finally, this returns the
160 Value *InsertCastBefore(Value *V, const Type *Ty, Instruction &Pos) {
161 if (V->getType() == Ty) return V;
163 Instruction *C = new CastInst(V, Ty, V->getName(), &Pos);
164 WorkList.push_back(C);
168 // ReplaceInstUsesWith - This method is to be used when an instruction is
169 // found to be dead, replacable with another preexisting expression. Here
170 // we add all uses of I to the worklist, replace all uses of I with the new
171 // value, then return I, so that the inst combiner will know that I was
174 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
175 AddUsersToWorkList(I); // Add all modified instrs to worklist
177 I.replaceAllUsesWith(V);
180 // If we are replacing the instruction with itself, this must be in a
181 // segment of unreachable code, so just clobber the instruction.
182 I.replaceAllUsesWith(UndefValue::get(I.getType()));
187 // EraseInstFromFunction - When dealing with an instruction that has side
188 // effects or produces a void value, we can't rely on DCE to delete the
189 // instruction. Instead, visit methods should return the value returned by
191 Instruction *EraseInstFromFunction(Instruction &I) {
192 assert(I.use_empty() && "Cannot erase instruction that is used!");
193 AddUsesToWorkList(I);
194 removeFromWorkList(&I);
196 return 0; // Don't do anything with FI
201 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
202 /// InsertBefore instruction. This is specialized a bit to avoid inserting
203 /// casts that are known to not do anything...
205 Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
206 Instruction *InsertBefore);
208 // SimplifyCommutative - This performs a few simplifications for commutative
210 bool SimplifyCommutative(BinaryOperator &I);
213 // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
214 // PHI node as operand #0, see if we can fold the instruction into the PHI
215 // (which is only possible if all operands to the PHI are constants).
216 Instruction *FoldOpIntoPhi(Instruction &I);
218 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
219 // operator and they all are only used by the PHI, PHI together their
220 // inputs, and do the operation once, to the result of the PHI.
221 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
223 Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
224 ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
226 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantIntegral *Mask,
227 bool isSub, Instruction &I);
228 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
229 bool Inside, Instruction &IB);
232 RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
235 // getComplexity: Assign a complexity or rank value to LLVM Values...
236 // 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
237 static unsigned getComplexity(Value *V) {
238 if (isa<Instruction>(V)) {
239 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
243 if (isa<Argument>(V)) return 3;
244 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
247 // isOnlyUse - Return true if this instruction will be deleted if we stop using
249 static bool isOnlyUse(Value *V) {
250 return V->hasOneUse() || isa<Constant>(V);
253 // getPromotedType - Return the specified type promoted as it would be to pass
254 // though a va_arg area...
255 static const Type *getPromotedType(const Type *Ty) {
256 switch (Ty->getTypeID()) {
257 case Type::SByteTyID:
258 case Type::ShortTyID: return Type::IntTy;
259 case Type::UByteTyID:
260 case Type::UShortTyID: return Type::UIntTy;
261 case Type::FloatTyID: return Type::DoubleTy;
266 /// isCast - If the specified operand is a CastInst or a constant expr cast,
267 /// return the operand value, otherwise return null.
268 static Value *isCast(Value *V) {
269 if (CastInst *I = dyn_cast<CastInst>(V))
270 return I->getOperand(0);
271 else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
272 if (CE->getOpcode() == Instruction::Cast)
273 return CE->getOperand(0);
277 // SimplifyCommutative - This performs a few simplifications for commutative
280 // 1. Order operands such that they are listed from right (least complex) to
281 // left (most complex). This puts constants before unary operators before
284 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
285 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
287 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
288 bool Changed = false;
289 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
290 Changed = !I.swapOperands();
292 if (!I.isAssociative()) return Changed;
293 Instruction::BinaryOps Opcode = I.getOpcode();
294 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
295 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
296 if (isa<Constant>(I.getOperand(1))) {
297 Constant *Folded = ConstantExpr::get(I.getOpcode(),
298 cast<Constant>(I.getOperand(1)),
299 cast<Constant>(Op->getOperand(1)));
300 I.setOperand(0, Op->getOperand(0));
301 I.setOperand(1, Folded);
303 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
304 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
305 isOnlyUse(Op) && isOnlyUse(Op1)) {
306 Constant *C1 = cast<Constant>(Op->getOperand(1));
307 Constant *C2 = cast<Constant>(Op1->getOperand(1));
309 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
310 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
311 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
314 WorkList.push_back(New);
315 I.setOperand(0, New);
316 I.setOperand(1, Folded);
323 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
324 // if the LHS is a constant zero (which is the 'negate' form).
326 static inline Value *dyn_castNegVal(Value *V) {
327 if (BinaryOperator::isNeg(V))
328 return BinaryOperator::getNegArgument(V);
330 // Constants can be considered to be negated values if they can be folded.
331 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
332 return ConstantExpr::getNeg(C);
336 static inline Value *dyn_castNotVal(Value *V) {
337 if (BinaryOperator::isNot(V))
338 return BinaryOperator::getNotArgument(V);
340 // Constants can be considered to be not'ed values...
341 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
342 return ConstantExpr::getNot(C);
346 // dyn_castFoldableMul - If this value is a multiply that can be folded into
347 // other computations (because it has a constant operand), return the
348 // non-constant operand of the multiply, and set CST to point to the multiplier.
349 // Otherwise, return null.
351 static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
352 if (V->hasOneUse() && V->getType()->isInteger())
353 if (Instruction *I = dyn_cast<Instruction>(V)) {
354 if (I->getOpcode() == Instruction::Mul)
355 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
356 return I->getOperand(0);
357 if (I->getOpcode() == Instruction::Shl)
358 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
359 // The multiplier is really 1 << CST.
360 Constant *One = ConstantInt::get(V->getType(), 1);
361 CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
362 return I->getOperand(0);
368 /// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
369 /// expression, return it.
370 static User *dyn_castGetElementPtr(Value *V) {
371 if (isa<GetElementPtrInst>(V)) return cast<User>(V);
372 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
373 if (CE->getOpcode() == Instruction::GetElementPtr)
374 return cast<User>(V);
378 // AddOne, SubOne - Add or subtract a constant one from an integer constant...
379 static ConstantInt *AddOne(ConstantInt *C) {
380 return cast<ConstantInt>(ConstantExpr::getAdd(C,
381 ConstantInt::get(C->getType(), 1)));
383 static ConstantInt *SubOne(ConstantInt *C) {
384 return cast<ConstantInt>(ConstantExpr::getSub(C,
385 ConstantInt::get(C->getType(), 1)));
388 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
389 /// this predicate to simplify operations downstream. V and Mask are known to
390 /// be the same type.
391 static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask) {
392 // Note, we cannot consider 'undef' to be "IsZero" here. The problem is that
393 // we cannot optimize based on the assumption that it is zero without changing
394 // to to an explicit zero. If we don't change it to zero, other code could
395 // optimized based on the contradictory assumption that it is non-zero.
396 // Because instcombine aggressively folds operations with undef args anyway,
397 // this won't lose us code quality.
398 if (Mask->isNullValue())
400 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
401 return ConstantExpr::getAnd(CI, Mask)->isNullValue();
403 if (Instruction *I = dyn_cast<Instruction>(V)) {
404 switch (I->getOpcode()) {
405 case Instruction::And:
406 // (X & C1) & C2 == 0 iff C1 & C2 == 0.
407 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1))) {
408 ConstantIntegral *C1C2 =
409 cast<ConstantIntegral>(ConstantExpr::getAnd(CI, Mask));
410 if (MaskedValueIsZero(I->getOperand(0), C1C2))
413 // If either the LHS or the RHS are MaskedValueIsZero, the result is zero.
414 return MaskedValueIsZero(I->getOperand(1), Mask) ||
415 MaskedValueIsZero(I->getOperand(0), Mask);
416 case Instruction::Or:
417 case Instruction::Xor:
418 // If the LHS and the RHS are MaskedValueIsZero, the result is also zero.
419 return MaskedValueIsZero(I->getOperand(1), Mask) &&
420 MaskedValueIsZero(I->getOperand(0), Mask);
421 case Instruction::Select:
422 // If the T and F values are MaskedValueIsZero, the result is also zero.
423 return MaskedValueIsZero(I->getOperand(2), Mask) &&
424 MaskedValueIsZero(I->getOperand(1), Mask);
425 case Instruction::Cast: {
426 const Type *SrcTy = I->getOperand(0)->getType();
427 if (SrcTy == Type::BoolTy)
428 return (Mask->getRawValue() & 1) == 0;
430 if (SrcTy->isInteger()) {
431 // (cast <ty> X to int) & C2 == 0 iff <ty> could not have contained C2.
432 if (SrcTy->isUnsigned() && // Only handle zero ext.
433 ConstantExpr::getCast(Mask, SrcTy)->isNullValue())
436 // If this is a noop cast, recurse.
437 if ((SrcTy->isSigned() && SrcTy->getUnsignedVersion() == I->getType())||
438 SrcTy->getSignedVersion() == I->getType()) {
440 ConstantExpr::getCast(Mask, I->getOperand(0)->getType());
441 return MaskedValueIsZero(I->getOperand(0),
442 cast<ConstantIntegral>(NewMask));
447 case Instruction::Shl:
448 // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
449 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
450 return MaskedValueIsZero(I->getOperand(0),
451 cast<ConstantIntegral>(ConstantExpr::getUShr(Mask, SA)));
453 case Instruction::Shr:
454 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
455 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
456 if (I->getType()->isUnsigned()) {
457 Constant *C1 = ConstantIntegral::getAllOnesValue(I->getType());
458 C1 = ConstantExpr::getShr(C1, SA);
459 C1 = ConstantExpr::getAnd(C1, Mask);
460 if (C1->isNullValue())
470 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
471 // true when both operands are equal...
473 static bool isTrueWhenEqual(Instruction &I) {
474 return I.getOpcode() == Instruction::SetEQ ||
475 I.getOpcode() == Instruction::SetGE ||
476 I.getOpcode() == Instruction::SetLE;
479 /// AssociativeOpt - Perform an optimization on an associative operator. This
480 /// function is designed to check a chain of associative operators for a
481 /// potential to apply a certain optimization. Since the optimization may be
482 /// applicable if the expression was reassociated, this checks the chain, then
483 /// reassociates the expression as necessary to expose the optimization
484 /// opportunity. This makes use of a special Functor, which must define
485 /// 'shouldApply' and 'apply' methods.
487 template<typename Functor>
488 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
489 unsigned Opcode = Root.getOpcode();
490 Value *LHS = Root.getOperand(0);
492 // Quick check, see if the immediate LHS matches...
493 if (F.shouldApply(LHS))
494 return F.apply(Root);
496 // Otherwise, if the LHS is not of the same opcode as the root, return.
497 Instruction *LHSI = dyn_cast<Instruction>(LHS);
498 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
499 // Should we apply this transform to the RHS?
500 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
502 // If not to the RHS, check to see if we should apply to the LHS...
503 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
504 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
508 // If the functor wants to apply the optimization to the RHS of LHSI,
509 // reassociate the expression from ((? op A) op B) to (? op (A op B))
511 BasicBlock *BB = Root.getParent();
513 // Now all of the instructions are in the current basic block, go ahead
514 // and perform the reassociation.
515 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
517 // First move the selected RHS to the LHS of the root...
518 Root.setOperand(0, LHSI->getOperand(1));
520 // Make what used to be the LHS of the root be the user of the root...
521 Value *ExtraOperand = TmpLHSI->getOperand(1);
522 if (&Root == TmpLHSI) {
523 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
526 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
527 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
528 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
529 BasicBlock::iterator ARI = &Root; ++ARI;
530 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
533 // Now propagate the ExtraOperand down the chain of instructions until we
535 while (TmpLHSI != LHSI) {
536 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
537 // Move the instruction to immediately before the chain we are
538 // constructing to avoid breaking dominance properties.
539 NextLHSI->getParent()->getInstList().remove(NextLHSI);
540 BB->getInstList().insert(ARI, NextLHSI);
543 Value *NextOp = NextLHSI->getOperand(1);
544 NextLHSI->setOperand(1, ExtraOperand);
546 ExtraOperand = NextOp;
549 // Now that the instructions are reassociated, have the functor perform
550 // the transformation...
551 return F.apply(Root);
554 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
560 // AddRHS - Implements: X + X --> X << 1
563 AddRHS(Value *rhs) : RHS(rhs) {}
564 bool shouldApply(Value *LHS) const { return LHS == RHS; }
565 Instruction *apply(BinaryOperator &Add) const {
566 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
567 ConstantInt::get(Type::UByteTy, 1));
571 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
573 struct AddMaskingAnd {
575 AddMaskingAnd(Constant *c) : C2(c) {}
576 bool shouldApply(Value *LHS) const {
578 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
579 ConstantExpr::getAnd(C1, C2)->isNullValue();
581 Instruction *apply(BinaryOperator &Add) const {
582 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
586 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
588 if (isa<CastInst>(I)) {
589 if (Constant *SOC = dyn_cast<Constant>(SO))
590 return ConstantExpr::getCast(SOC, I.getType());
592 return IC->InsertNewInstBefore(new CastInst(SO, I.getType(),
593 SO->getName() + ".cast"), I);
596 // Figure out if the constant is the left or the right argument.
597 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
598 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
600 if (Constant *SOC = dyn_cast<Constant>(SO)) {
602 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
603 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
606 Value *Op0 = SO, *Op1 = ConstOperand;
610 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
611 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
612 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&I))
613 New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh");
615 assert(0 && "Unknown binary instruction type!");
618 return IC->InsertNewInstBefore(New, I);
621 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
622 // constant as the other operand, try to fold the binary operator into the
623 // select arguments. This also works for Cast instructions, which obviously do
624 // not have a second operand.
625 static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
627 // Don't modify shared select instructions
628 if (!SI->hasOneUse()) return 0;
629 Value *TV = SI->getOperand(1);
630 Value *FV = SI->getOperand(2);
632 if (isa<Constant>(TV) || isa<Constant>(FV)) {
633 // Bool selects with constant operands can be folded to logical ops.
634 if (SI->getType() == Type::BoolTy) return 0;
636 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
637 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
639 return new SelectInst(SI->getCondition(), SelectTrueVal,
646 /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
647 /// node as operand #0, see if we can fold the instruction into the PHI (which
648 /// is only possible if all operands to the PHI are constants).
649 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
650 PHINode *PN = cast<PHINode>(I.getOperand(0));
651 unsigned NumPHIValues = PN->getNumIncomingValues();
652 if (!PN->hasOneUse() || NumPHIValues == 0 ||
653 !isa<Constant>(PN->getIncomingValue(0))) return 0;
655 // Check to see if all of the operands of the PHI are constants. If not, we
656 // cannot do the transformation.
657 for (unsigned i = 1; i != NumPHIValues; ++i)
658 if (!isa<Constant>(PN->getIncomingValue(i)))
661 // Okay, we can do the transformation: create the new PHI node.
662 PHINode *NewPN = new PHINode(I.getType(), I.getName());
664 NewPN->reserveOperandSpace(PN->getNumOperands()/2);
665 InsertNewInstBefore(NewPN, *PN);
667 // Next, add all of the operands to the PHI.
668 if (I.getNumOperands() == 2) {
669 Constant *C = cast<Constant>(I.getOperand(1));
670 for (unsigned i = 0; i != NumPHIValues; ++i) {
671 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
672 NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
673 PN->getIncomingBlock(i));
676 assert(isa<CastInst>(I) && "Unary op should be a cast!");
677 const Type *RetTy = I.getType();
678 for (unsigned i = 0; i != NumPHIValues; ++i) {
679 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
680 NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
681 PN->getIncomingBlock(i));
684 return ReplaceInstUsesWith(I, NewPN);
687 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
688 bool Changed = SimplifyCommutative(I);
689 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
691 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
692 // X + undef -> undef
693 if (isa<UndefValue>(RHS))
694 return ReplaceInstUsesWith(I, RHS);
697 if (!I.getType()->isFloatingPoint() && // -0 + +0 = +0, so it's not a noop
699 return ReplaceInstUsesWith(I, LHS);
701 // X + (signbit) --> X ^ signbit
702 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
703 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
704 uint64_t Val = CI->getRawValue() & (1ULL << NumBits)-1;
705 if (Val == (1ULL << (NumBits-1)))
706 return BinaryOperator::createXor(LHS, RHS);
709 if (isa<PHINode>(LHS))
710 if (Instruction *NV = FoldOpIntoPhi(I))
715 if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
716 unsigned TySizeBits = I.getType()->getPrimitiveSizeInBits();
717 int64_t RHSSExt = cast<ConstantInt>(RHSC)->getSExtValue();
718 uint64_t RHSZExt = cast<ConstantInt>(RHSC)->getZExtValue();
720 uint64_t C0080Val = 1ULL << 31;
721 int64_t CFF80Val = -C0080Val;
724 if (TySizeBits > Size) {
726 // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
727 // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
728 if (RHSSExt == CFF80Val) {
729 if (XorRHS->getZExtValue() == C0080Val)
731 } else if (RHSZExt == C0080Val) {
732 if (XorRHS->getSExtValue() == CFF80Val)
736 // This is a sign extend if the top bits are known zero.
737 Constant *Mask = ConstantInt::getAllOnesValue(XorLHS->getType());
738 Mask = ConstantExpr::getShl(Mask,
739 ConstantInt::get(Type::UByteTy, 64-TySizeBits-Size));
740 if (!MaskedValueIsZero(XorLHS, cast<ConstantInt>(Mask)))
741 Size = 0; // Not a sign ext, but can't be any others either.
751 const Type *MiddleType = 0;
754 case 32: MiddleType = Type::IntTy; break;
755 case 16: MiddleType = Type::ShortTy; break;
756 case 8: MiddleType = Type::SByteTy; break;
759 Instruction *NewTrunc = new CastInst(XorLHS, MiddleType, "sext");
760 InsertNewInstBefore(NewTrunc, I);
761 return new CastInst(NewTrunc, I.getType());
767 if (I.getType()->isInteger()) {
768 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
770 if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
771 if (RHSI->getOpcode() == Instruction::Sub)
772 if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
773 return ReplaceInstUsesWith(I, RHSI->getOperand(0));
775 if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
776 if (LHSI->getOpcode() == Instruction::Sub)
777 if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
778 return ReplaceInstUsesWith(I, LHSI->getOperand(0));
783 if (Value *V = dyn_castNegVal(LHS))
784 return BinaryOperator::createSub(RHS, V);
787 if (!isa<Constant>(RHS))
788 if (Value *V = dyn_castNegVal(RHS))
789 return BinaryOperator::createSub(LHS, V);
793 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
794 if (X == RHS) // X*C + X --> X * (C+1)
795 return BinaryOperator::createMul(RHS, AddOne(C2));
797 // X*C1 + X*C2 --> X * (C1+C2)
799 if (X == dyn_castFoldableMul(RHS, C1))
800 return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2));
803 // X + X*C --> X * (C+1)
804 if (dyn_castFoldableMul(RHS, C2) == LHS)
805 return BinaryOperator::createMul(LHS, AddOne(C2));
808 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
809 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
810 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
812 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
814 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
815 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
816 return BinaryOperator::createSub(C, X);
819 // (X & FF00) + xx00 -> (X+xx00) & FF00
820 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
821 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
823 // See if all bits from the first bit set in the Add RHS up are included
824 // in the mask. First, get the rightmost bit.
825 uint64_t AddRHSV = CRHS->getRawValue();
827 // Form a mask of all bits from the lowest bit added through the top.
828 uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
829 AddRHSHighBits &= ~0ULL >> (64-C2->getType()->getPrimitiveSizeInBits());
831 // See if the and mask includes all of these bits.
832 uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue();
834 if (AddRHSHighBits == AddRHSHighBitsAnd) {
835 // Okay, the xform is safe. Insert the new add pronto.
836 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
838 return BinaryOperator::createAnd(NewAdd, C2);
843 // Try to fold constant add into select arguments.
844 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
845 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
849 return Changed ? &I : 0;
852 // isSignBit - Return true if the value represented by the constant only has the
853 // highest order bit set.
854 static bool isSignBit(ConstantInt *CI) {
855 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
856 return (CI->getRawValue() & (~0ULL >> (64-NumBits))) == (1ULL << (NumBits-1));
859 /// RemoveNoopCast - Strip off nonconverting casts from the value.
861 static Value *RemoveNoopCast(Value *V) {
862 if (CastInst *CI = dyn_cast<CastInst>(V)) {
863 const Type *CTy = CI->getType();
864 const Type *OpTy = CI->getOperand(0)->getType();
865 if (CTy->isInteger() && OpTy->isInteger()) {
866 if (CTy->getPrimitiveSizeInBits() == OpTy->getPrimitiveSizeInBits())
867 return RemoveNoopCast(CI->getOperand(0));
868 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
869 return RemoveNoopCast(CI->getOperand(0));
874 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
875 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
877 if (Op0 == Op1) // sub X, X -> 0
878 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
880 // If this is a 'B = x-(-A)', change to B = x+A...
881 if (Value *V = dyn_castNegVal(Op1))
882 return BinaryOperator::createAdd(Op0, V);
884 if (isa<UndefValue>(Op0))
885 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
886 if (isa<UndefValue>(Op1))
887 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
889 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
890 // Replace (-1 - A) with (~A)...
891 if (C->isAllOnesValue())
892 return BinaryOperator::createNot(Op1);
894 // C - ~X == X + (1+C)
896 if (match(Op1, m_Not(m_Value(X))))
897 return BinaryOperator::createAdd(X,
898 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
899 // -((uint)X >> 31) -> ((int)X >> 31)
900 // -((int)X >> 31) -> ((uint)X >> 31)
901 if (C->isNullValue()) {
902 Value *NoopCastedRHS = RemoveNoopCast(Op1);
903 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
904 if (SI->getOpcode() == Instruction::Shr)
905 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
907 if (SI->getType()->isSigned())
908 NewTy = SI->getType()->getUnsignedVersion();
910 NewTy = SI->getType()->getSignedVersion();
911 // Check to see if we are shifting out everything but the sign bit.
912 if (CU->getValue() == SI->getType()->getPrimitiveSizeInBits()-1) {
913 // Ok, the transformation is safe. Insert a cast of the incoming
914 // value, then the new shift, then the new cast.
915 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
916 SI->getOperand(0)->getName());
917 Value *InV = InsertNewInstBefore(FirstCast, I);
918 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
920 if (NewShift->getType() == I.getType())
923 InV = InsertNewInstBefore(NewShift, I);
924 return new CastInst(NewShift, I.getType());
930 // Try to fold constant sub into select arguments.
931 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
932 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
935 if (isa<PHINode>(Op0))
936 if (Instruction *NV = FoldOpIntoPhi(I))
940 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
941 if (Op1I->getOpcode() == Instruction::Add &&
942 !Op0->getType()->isFloatingPoint()) {
943 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
944 return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
945 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
946 return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
947 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
948 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
949 // C1-(X+C2) --> (C1-C2)-X
950 return BinaryOperator::createSub(ConstantExpr::getSub(CI1, CI2),
951 Op1I->getOperand(0));
955 if (Op1I->hasOneUse()) {
956 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
957 // is not used by anyone else...
959 if (Op1I->getOpcode() == Instruction::Sub &&
960 !Op1I->getType()->isFloatingPoint()) {
961 // Swap the two operands of the subexpr...
962 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
963 Op1I->setOperand(0, IIOp1);
964 Op1I->setOperand(1, IIOp0);
966 // Create the new top level add instruction...
967 return BinaryOperator::createAdd(Op0, Op1);
970 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
972 if (Op1I->getOpcode() == Instruction::And &&
973 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
974 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
977 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
978 return BinaryOperator::createAnd(Op0, NewNot);
981 // -(X sdiv C) -> (X sdiv -C)
982 if (Op1I->getOpcode() == Instruction::Div)
983 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
984 if (CSI->isNullValue())
985 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
986 return BinaryOperator::createDiv(Op1I->getOperand(0),
987 ConstantExpr::getNeg(DivRHS));
989 // X - X*C --> X * (1-C)
991 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
993 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
994 return BinaryOperator::createMul(Op0, CP1);
999 if (!Op0->getType()->isFloatingPoint())
1000 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
1001 if (Op0I->getOpcode() == Instruction::Add) {
1002 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
1003 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
1004 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
1005 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
1006 } else if (Op0I->getOpcode() == Instruction::Sub) {
1007 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
1008 return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName());
1012 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
1013 if (X == Op1) { // X*C - X --> X * (C-1)
1014 Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
1015 return BinaryOperator::createMul(Op1, CP1);
1018 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
1019 if (X == dyn_castFoldableMul(Op1, C2))
1020 return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
1025 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
1026 /// really just returns true if the most significant (sign) bit is set.
1027 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
1028 if (RHS->getType()->isSigned()) {
1029 // True if source is LHS < 0 or LHS <= -1
1030 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
1031 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
1033 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
1034 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
1035 // the size of the integer type.
1036 if (Opcode == Instruction::SetGE)
1037 return RHSC->getValue() ==
1038 1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1);
1039 if (Opcode == Instruction::SetGT)
1040 return RHSC->getValue() ==
1041 (1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1))-1;
1046 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
1047 bool Changed = SimplifyCommutative(I);
1048 Value *Op0 = I.getOperand(0);
1050 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
1051 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1053 // Simplify mul instructions with a constant RHS...
1054 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
1055 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
1057 // ((X << C1)*C2) == (X * (C2 << C1))
1058 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
1059 if (SI->getOpcode() == Instruction::Shl)
1060 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
1061 return BinaryOperator::createMul(SI->getOperand(0),
1062 ConstantExpr::getShl(CI, ShOp));
1064 if (CI->isNullValue())
1065 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
1066 if (CI->equalsInt(1)) // X * 1 == X
1067 return ReplaceInstUsesWith(I, Op0);
1068 if (CI->isAllOnesValue()) // X * -1 == 0 - X
1069 return BinaryOperator::createNeg(Op0, I.getName());
1071 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
1072 if (isPowerOf2_64(Val)) { // Replace X*(2^C) with X << C
1073 uint64_t C = Log2_64(Val);
1074 return new ShiftInst(Instruction::Shl, Op0,
1075 ConstantUInt::get(Type::UByteTy, C));
1077 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
1078 if (Op1F->isNullValue())
1079 return ReplaceInstUsesWith(I, Op1);
1081 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
1082 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
1083 if (Op1F->getValue() == 1.0)
1084 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
1087 // Try to fold constant mul into select arguments.
1088 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1089 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1092 if (isa<PHINode>(Op0))
1093 if (Instruction *NV = FoldOpIntoPhi(I))
1097 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
1098 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
1099 return BinaryOperator::createMul(Op0v, Op1v);
1101 // If one of the operands of the multiply is a cast from a boolean value, then
1102 // we know the bool is either zero or one, so this is a 'masking' multiply.
1103 // See if we can simplify things based on how the boolean was originally
1105 CastInst *BoolCast = 0;
1106 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
1107 if (CI->getOperand(0)->getType() == Type::BoolTy)
1110 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
1111 if (CI->getOperand(0)->getType() == Type::BoolTy)
1114 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
1115 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
1116 const Type *SCOpTy = SCIOp0->getType();
1118 // If the setcc is true iff the sign bit of X is set, then convert this
1119 // multiply into a shift/and combination.
1120 if (isa<ConstantInt>(SCIOp1) &&
1121 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
1122 // Shift the X value right to turn it into "all signbits".
1123 Constant *Amt = ConstantUInt::get(Type::UByteTy,
1124 SCOpTy->getPrimitiveSizeInBits()-1);
1125 if (SCIOp0->getType()->isUnsigned()) {
1126 const Type *NewTy = SCIOp0->getType()->getSignedVersion();
1127 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
1128 SCIOp0->getName()), I);
1132 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
1133 BoolCast->getOperand(0)->getName()+
1136 // If the multiply type is not the same as the source type, sign extend
1137 // or truncate to the multiply type.
1138 if (I.getType() != V->getType())
1139 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
1141 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
1142 return BinaryOperator::createAnd(V, OtherOp);
1147 return Changed ? &I : 0;
1150 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
1151 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1153 if (isa<UndefValue>(Op0)) // undef / X -> 0
1154 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1155 if (isa<UndefValue>(Op1))
1156 return ReplaceInstUsesWith(I, Op1); // X / undef -> undef
1158 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1160 if (RHS->equalsInt(1))
1161 return ReplaceInstUsesWith(I, Op0);
1164 if (RHS->isAllOnesValue())
1165 return BinaryOperator::createNeg(Op0);
1167 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
1168 if (LHS->getOpcode() == Instruction::Div)
1169 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
1170 // (X / C1) / C2 -> X / (C1*C2)
1171 return BinaryOperator::createDiv(LHS->getOperand(0),
1172 ConstantExpr::getMul(RHS, LHSRHS));
1175 // Check to see if this is an unsigned division with an exact power of 2,
1176 // if so, convert to a right shift.
1177 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1178 if (uint64_t Val = C->getValue()) // Don't break X / 0
1179 if (isPowerOf2_64(Val)) {
1180 uint64_t C = Log2_64(Val);
1181 return new ShiftInst(Instruction::Shr, Op0,
1182 ConstantUInt::get(Type::UByteTy, C));
1186 if (RHS->getType()->isSigned())
1187 if (Value *LHSNeg = dyn_castNegVal(Op0))
1188 return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS));
1190 if (!RHS->isNullValue()) {
1191 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1192 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1194 if (isa<PHINode>(Op0))
1195 if (Instruction *NV = FoldOpIntoPhi(I))
1200 // If this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1201 // transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'.
1202 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1203 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1204 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1205 if (STO->getValue() == 0) { // Couldn't be this argument.
1206 I.setOperand(1, SFO);
1208 } else if (SFO->getValue() == 0) {
1209 I.setOperand(1, STO);
1213 uint64_t TVA = STO->getValue(), FVA = SFO->getValue();
1214 if (isPowerOf2_64(TVA) && isPowerOf2_64(FVA)) {
1215 unsigned TSA = Log2_64(TVA), FSA = Log2_64(FVA);
1216 Constant *TC = ConstantUInt::get(Type::UByteTy, TSA);
1217 Instruction *TSI = new ShiftInst(Instruction::Shr, Op0,
1218 TC, SI->getName()+".t");
1219 TSI = InsertNewInstBefore(TSI, I);
1221 Constant *FC = ConstantUInt::get(Type::UByteTy, FSA);
1222 Instruction *FSI = new ShiftInst(Instruction::Shr, Op0,
1223 FC, SI->getName()+".f");
1224 FSI = InsertNewInstBefore(FSI, I);
1225 return new SelectInst(SI->getOperand(0), TSI, FSI);
1229 // 0 / X == 0, we don't need to preserve faults!
1230 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1231 if (LHS->equalsInt(0))
1232 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1238 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
1239 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1240 if (I.getType()->isSigned())
1241 if (Value *RHSNeg = dyn_castNegVal(Op1))
1242 if (!isa<ConstantSInt>(RHSNeg) ||
1243 cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
1245 AddUsesToWorkList(I);
1246 I.setOperand(1, RHSNeg);
1250 if (isa<UndefValue>(Op0)) // undef % X -> 0
1251 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1252 if (isa<UndefValue>(Op1))
1253 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
1255 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1256 if (RHS->equalsInt(1)) // X % 1 == 0
1257 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1259 // Check to see if this is an unsigned remainder with an exact power of 2,
1260 // if so, convert to a bitwise and.
1261 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1262 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
1263 if (!(Val & (Val-1))) // Power of 2
1264 return BinaryOperator::createAnd(Op0,
1265 ConstantUInt::get(I.getType(), Val-1));
1267 if (!RHS->isNullValue()) {
1268 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1269 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1271 if (isa<PHINode>(Op0))
1272 if (Instruction *NV = FoldOpIntoPhi(I))
1277 // If this is 'urem X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1278 // transform this into: '(Cond ? (urem X, C1) : (urem X, C2))'.
1279 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1280 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1281 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1282 if (STO->getValue() == 0) { // Couldn't be this argument.
1283 I.setOperand(1, SFO);
1285 } else if (SFO->getValue() == 0) {
1286 I.setOperand(1, STO);
1290 if (!(STO->getValue() & (STO->getValue()-1)) &&
1291 !(SFO->getValue() & (SFO->getValue()-1))) {
1292 Value *TrueAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1293 SubOne(STO), SI->getName()+".t"), I);
1294 Value *FalseAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1295 SubOne(SFO), SI->getName()+".f"), I);
1296 return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
1300 // 0 % X == 0, we don't need to preserve faults!
1301 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1302 if (LHS->equalsInt(0))
1303 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1308 // isMaxValueMinusOne - return true if this is Max-1
1309 static bool isMaxValueMinusOne(const ConstantInt *C) {
1310 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
1311 // Calculate -1 casted to the right type...
1312 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1313 uint64_t Val = ~0ULL; // All ones
1314 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1315 return CU->getValue() == Val-1;
1318 const ConstantSInt *CS = cast<ConstantSInt>(C);
1320 // Calculate 0111111111..11111
1321 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1322 int64_t Val = INT64_MAX; // All ones
1323 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1324 return CS->getValue() == Val-1;
1327 // isMinValuePlusOne - return true if this is Min+1
1328 static bool isMinValuePlusOne(const ConstantInt *C) {
1329 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1330 return CU->getValue() == 1;
1332 const ConstantSInt *CS = cast<ConstantSInt>(C);
1334 // Calculate 1111111111000000000000
1335 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1336 int64_t Val = -1; // All ones
1337 Val <<= TypeBits-1; // Shift over to the right spot
1338 return CS->getValue() == Val+1;
1341 // isOneBitSet - Return true if there is exactly one bit set in the specified
1343 static bool isOneBitSet(const ConstantInt *CI) {
1344 uint64_t V = CI->getRawValue();
1345 return V && (V & (V-1)) == 0;
1348 #if 0 // Currently unused
1349 // isLowOnes - Return true if the constant is of the form 0+1+.
1350 static bool isLowOnes(const ConstantInt *CI) {
1351 uint64_t V = CI->getRawValue();
1353 // There won't be bits set in parts that the type doesn't contain.
1354 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1356 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1357 return U && V && (U & V) == 0;
1361 // isHighOnes - Return true if the constant is of the form 1+0+.
1362 // This is the same as lowones(~X).
1363 static bool isHighOnes(const ConstantInt *CI) {
1364 uint64_t V = ~CI->getRawValue();
1365 if (~V == 0) return false; // 0's does not match "1+"
1367 // There won't be bits set in parts that the type doesn't contain.
1368 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1370 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1371 return U && V && (U & V) == 0;
1375 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
1376 /// are carefully arranged to allow folding of expressions such as:
1378 /// (A < B) | (A > B) --> (A != B)
1380 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
1381 /// represents that the comparison is true if A == B, and bit value '1' is true
1384 static unsigned getSetCondCode(const SetCondInst *SCI) {
1385 switch (SCI->getOpcode()) {
1387 case Instruction::SetGT: return 1;
1388 case Instruction::SetEQ: return 2;
1389 case Instruction::SetGE: return 3;
1390 case Instruction::SetLT: return 4;
1391 case Instruction::SetNE: return 5;
1392 case Instruction::SetLE: return 6;
1395 assert(0 && "Invalid SetCC opcode!");
1400 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
1401 /// opcode and two operands into either a constant true or false, or a brand new
1402 /// SetCC instruction.
1403 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
1405 case 0: return ConstantBool::False;
1406 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
1407 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
1408 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
1409 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
1410 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
1411 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
1412 case 7: return ConstantBool::True;
1413 default: assert(0 && "Illegal SetCCCode!"); return 0;
1417 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1418 struct FoldSetCCLogical {
1421 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
1422 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
1423 bool shouldApply(Value *V) const {
1424 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
1425 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
1426 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
1429 Instruction *apply(BinaryOperator &Log) const {
1430 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
1431 if (SCI->getOperand(0) != LHS) {
1432 assert(SCI->getOperand(1) == LHS);
1433 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
1436 unsigned LHSCode = getSetCondCode(SCI);
1437 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
1439 switch (Log.getOpcode()) {
1440 case Instruction::And: Code = LHSCode & RHSCode; break;
1441 case Instruction::Or: Code = LHSCode | RHSCode; break;
1442 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
1443 default: assert(0 && "Illegal logical opcode!"); return 0;
1446 Value *RV = getSetCCValue(Code, LHS, RHS);
1447 if (Instruction *I = dyn_cast<Instruction>(RV))
1449 // Otherwise, it's a constant boolean value...
1450 return IC.ReplaceInstUsesWith(Log, RV);
1454 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
1455 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
1456 // guaranteed to be either a shift instruction or a binary operator.
1457 Instruction *InstCombiner::OptAndOp(Instruction *Op,
1458 ConstantIntegral *OpRHS,
1459 ConstantIntegral *AndRHS,
1460 BinaryOperator &TheAnd) {
1461 Value *X = Op->getOperand(0);
1462 Constant *Together = 0;
1463 if (!isa<ShiftInst>(Op))
1464 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
1466 switch (Op->getOpcode()) {
1467 case Instruction::Xor:
1468 if (Op->hasOneUse()) {
1469 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
1470 std::string OpName = Op->getName(); Op->setName("");
1471 Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
1472 InsertNewInstBefore(And, TheAnd);
1473 return BinaryOperator::createXor(And, Together);
1476 case Instruction::Or:
1477 if (Together == AndRHS) // (X | C) & C --> C
1478 return ReplaceInstUsesWith(TheAnd, AndRHS);
1480 if (Op->hasOneUse() && Together != OpRHS) {
1481 // (X | C1) & C2 --> (X | (C1&C2)) & C2
1482 std::string Op0Name = Op->getName(); Op->setName("");
1483 Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
1484 InsertNewInstBefore(Or, TheAnd);
1485 return BinaryOperator::createAnd(Or, AndRHS);
1488 case Instruction::Add:
1489 if (Op->hasOneUse()) {
1490 // Adding a one to a single bit bit-field should be turned into an XOR
1491 // of the bit. First thing to check is to see if this AND is with a
1492 // single bit constant.
1493 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
1495 // Clear bits that are not part of the constant.
1496 AndRHSV &= ~0ULL >> (64-AndRHS->getType()->getPrimitiveSizeInBits());
1498 // If there is only one bit set...
1499 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
1500 // Ok, at this point, we know that we are masking the result of the
1501 // ADD down to exactly one bit. If the constant we are adding has
1502 // no bits set below this bit, then we can eliminate the ADD.
1503 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
1505 // Check to see if any bits below the one bit set in AndRHSV are set.
1506 if ((AddRHS & (AndRHSV-1)) == 0) {
1507 // If not, the only thing that can effect the output of the AND is
1508 // the bit specified by AndRHSV. If that bit is set, the effect of
1509 // the XOR is to toggle the bit. If it is clear, then the ADD has
1511 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
1512 TheAnd.setOperand(0, X);
1515 std::string Name = Op->getName(); Op->setName("");
1516 // Pull the XOR out of the AND.
1517 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
1518 InsertNewInstBefore(NewAnd, TheAnd);
1519 return BinaryOperator::createXor(NewAnd, AndRHS);
1526 case Instruction::Shl: {
1527 // We know that the AND will not produce any of the bits shifted in, so if
1528 // the anded constant includes them, clear them now!
1530 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1531 Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
1532 Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
1534 if (CI == ShlMask) { // Masking out bits that the shift already masks
1535 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
1536 } else if (CI != AndRHS) { // Reducing bits set in and.
1537 TheAnd.setOperand(1, CI);
1542 case Instruction::Shr:
1543 // We know that the AND will not produce any of the bits shifted in, so if
1544 // the anded constant includes them, clear them now! This only applies to
1545 // unsigned shifts, because a signed shr may bring in set bits!
1547 if (AndRHS->getType()->isUnsigned()) {
1548 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1549 Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS);
1550 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1552 if (CI == ShrMask) { // Masking out bits that the shift already masks.
1553 return ReplaceInstUsesWith(TheAnd, Op);
1554 } else if (CI != AndRHS) {
1555 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
1558 } else { // Signed shr.
1559 // See if this is shifting in some sign extension, then masking it out
1561 if (Op->hasOneUse()) {
1562 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1563 Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS);
1564 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1565 if (CI == AndRHS) { // Masking out bits shifted in.
1566 // Make the argument unsigned.
1567 Value *ShVal = Op->getOperand(0);
1568 ShVal = InsertCastBefore(ShVal,
1569 ShVal->getType()->getUnsignedVersion(),
1571 ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal,
1572 OpRHS, Op->getName()),
1574 Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType());
1575 ShVal = InsertNewInstBefore(BinaryOperator::createAnd(ShVal, AndRHS2,
1578 return new CastInst(ShVal, Op->getType());
1588 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
1589 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
1590 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. IB is the location to
1591 /// insert new instructions.
1592 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
1593 bool Inside, Instruction &IB) {
1594 assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
1595 "Lo is not <= Hi in range emission code!");
1597 if (Lo == Hi) // Trivially false.
1598 return new SetCondInst(Instruction::SetNE, V, V);
1599 if (cast<ConstantIntegral>(Lo)->isMinValue())
1600 return new SetCondInst(Instruction::SetLT, V, Hi);
1602 Constant *AddCST = ConstantExpr::getNeg(Lo);
1603 Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
1604 InsertNewInstBefore(Add, IB);
1605 // Convert to unsigned for the comparison.
1606 const Type *UnsType = Add->getType()->getUnsignedVersion();
1607 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1608 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1609 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1610 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1613 if (Lo == Hi) // Trivially true.
1614 return new SetCondInst(Instruction::SetEQ, V, V);
1616 Hi = SubOne(cast<ConstantInt>(Hi));
1617 if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
1618 return new SetCondInst(Instruction::SetGT, V, Hi);
1620 // Emit X-Lo > Hi-Lo-1
1621 Constant *AddCST = ConstantExpr::getNeg(Lo);
1622 Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
1623 InsertNewInstBefore(Add, IB);
1624 // Convert to unsigned for the comparison.
1625 const Type *UnsType = Add->getType()->getUnsignedVersion();
1626 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1627 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1628 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1629 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1632 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
1633 // any number of 0s on either side. The 1s are allowed to wrap from LSB to
1634 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
1635 // not, since all 1s are not contiguous.
1636 static bool isRunOfOnes(ConstantIntegral *Val, unsigned &MB, unsigned &ME) {
1637 uint64_t V = Val->getRawValue();
1638 if (!isShiftedMask_64(V)) return false;
1640 // look for the first zero bit after the run of ones
1641 MB = 64-CountLeadingZeros_64((V - 1) ^ V);
1642 // look for the first non-zero bit
1643 ME = 64-CountLeadingZeros_64(V);
1649 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
1650 /// where isSub determines whether the operator is a sub. If we can fold one of
1651 /// the following xforms:
1653 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
1654 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
1655 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
1657 /// return (A +/- B).
1659 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
1660 ConstantIntegral *Mask, bool isSub,
1662 Instruction *LHSI = dyn_cast<Instruction>(LHS);
1663 if (!LHSI || LHSI->getNumOperands() != 2 ||
1664 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
1666 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
1668 switch (LHSI->getOpcode()) {
1670 case Instruction::And:
1671 if (ConstantExpr::getAnd(N, Mask) == Mask) {
1672 // If the AndRHS is a power of two minus one (0+1+), this is simple.
1673 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0)
1676 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
1677 // part, we don't need any explicit masks to take them out of A. If that
1678 // is all N is, ignore it.
1680 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
1681 Constant *Mask = ConstantInt::getAllOnesValue(RHS->getType());
1682 Mask = ConstantExpr::getUShr(Mask,
1683 ConstantInt::get(Type::UByteTy,
1685 if (MaskedValueIsZero(RHS, cast<ConstantIntegral>(Mask)))
1690 case Instruction::Or:
1691 case Instruction::Xor:
1692 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
1693 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0 &&
1694 ConstantExpr::getAnd(N, Mask)->isNullValue())
1701 New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold");
1703 New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold");
1704 return InsertNewInstBefore(New, I);
1708 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1709 bool Changed = SimplifyCommutative(I);
1710 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1712 if (isa<UndefValue>(Op1)) // X & undef -> 0
1713 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1717 return ReplaceInstUsesWith(I, Op1);
1719 if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) {
1721 if (AndRHS->isAllOnesValue())
1722 return ReplaceInstUsesWith(I, Op0);
1724 if (MaskedValueIsZero(Op0, AndRHS)) // LHS & RHS == 0
1725 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1727 // If the mask is not masking out any bits, there is no reason to do the
1728 // and in the first place.
1729 ConstantIntegral *NotAndRHS =
1730 cast<ConstantIntegral>(ConstantExpr::getNot(AndRHS));
1731 if (MaskedValueIsZero(Op0, NotAndRHS))
1732 return ReplaceInstUsesWith(I, Op0);
1734 // Optimize a variety of ((val OP C1) & C2) combinations...
1735 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
1736 Instruction *Op0I = cast<Instruction>(Op0);
1737 Value *Op0LHS = Op0I->getOperand(0);
1738 Value *Op0RHS = Op0I->getOperand(1);
1739 switch (Op0I->getOpcode()) {
1740 case Instruction::Xor:
1741 case Instruction::Or:
1742 // (X ^ V) & C2 --> (X & C2) iff (V & C2) == 0
1743 // (X | V) & C2 --> (X & C2) iff (V & C2) == 0
1744 if (MaskedValueIsZero(Op0LHS, AndRHS))
1745 return BinaryOperator::createAnd(Op0RHS, AndRHS);
1746 if (MaskedValueIsZero(Op0RHS, AndRHS))
1747 return BinaryOperator::createAnd(Op0LHS, AndRHS);
1749 // If the mask is only needed on one incoming arm, push it up.
1750 if (Op0I->hasOneUse()) {
1751 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
1752 // Not masking anything out for the LHS, move to RHS.
1753 Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
1754 Op0RHS->getName()+".masked");
1755 InsertNewInstBefore(NewRHS, I);
1756 return BinaryOperator::create(
1757 cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
1759 if (!isa<Constant>(NotAndRHS) &&
1760 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
1761 // Not masking anything out for the RHS, move to LHS.
1762 Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
1763 Op0LHS->getName()+".masked");
1764 InsertNewInstBefore(NewLHS, I);
1765 return BinaryOperator::create(
1766 cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
1771 case Instruction::And:
1772 // (X & V) & C2 --> 0 iff (V & C2) == 0
1773 if (MaskedValueIsZero(Op0LHS, AndRHS) ||
1774 MaskedValueIsZero(Op0RHS, AndRHS))
1775 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1777 case Instruction::Add:
1778 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
1779 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1780 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1781 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
1782 return BinaryOperator::createAnd(V, AndRHS);
1783 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
1784 return BinaryOperator::createAnd(V, AndRHS); // Add commutes
1787 case Instruction::Sub:
1788 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
1789 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1790 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1791 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
1792 return BinaryOperator::createAnd(V, AndRHS);
1796 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1797 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
1799 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
1800 const Type *SrcTy = CI->getOperand(0)->getType();
1802 // If this is an integer truncation or change from signed-to-unsigned, and
1803 // if the source is an and/or with immediate, transform it. This
1804 // frequently occurs for bitfield accesses.
1805 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
1806 if (SrcTy->getPrimitiveSizeInBits() >=
1807 I.getType()->getPrimitiveSizeInBits() &&
1808 CastOp->getNumOperands() == 2)
1809 if (ConstantInt *AndCI =dyn_cast<ConstantInt>(CastOp->getOperand(1)))
1810 if (CastOp->getOpcode() == Instruction::And) {
1811 // Change: and (cast (and X, C1) to T), C2
1812 // into : and (cast X to T), trunc(C1)&C2
1813 // This will folds the two ands together, which may allow other
1815 Instruction *NewCast =
1816 new CastInst(CastOp->getOperand(0), I.getType(),
1817 CastOp->getName()+".shrunk");
1818 NewCast = InsertNewInstBefore(NewCast, I);
1820 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1821 C3 = ConstantExpr::getAnd(C3, AndRHS); // trunc(C1)&C2
1822 return BinaryOperator::createAnd(NewCast, C3);
1823 } else if (CastOp->getOpcode() == Instruction::Or) {
1824 // Change: and (cast (or X, C1) to T), C2
1825 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
1826 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1827 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
1828 return ReplaceInstUsesWith(I, AndRHS);
1833 // If this is an integer sign or zero extension instruction.
1834 if (SrcTy->isIntegral() &&
1835 SrcTy->getPrimitiveSizeInBits() <
1836 CI->getType()->getPrimitiveSizeInBits()) {
1838 if (SrcTy->isUnsigned()) {
1839 // See if this and is clearing out bits that are known to be zero
1840 // anyway (due to the zero extension).
1841 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1842 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1843 Constant *Result = ConstantExpr::getAnd(Mask, AndRHS);
1844 if (Result == Mask) // The "and" isn't doing anything, remove it.
1845 return ReplaceInstUsesWith(I, CI);
1846 if (Result != AndRHS) { // Reduce the and RHS constant.
1847 I.setOperand(1, Result);
1852 if (CI->hasOneUse() && SrcTy->isInteger()) {
1853 // We can only do this if all of the sign bits brought in are masked
1854 // out. Compute this by first getting 0000011111, then inverting
1856 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1857 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1858 Mask = ConstantExpr::getNot(Mask); // 1's in the new bits.
1859 if (ConstantExpr::getAnd(Mask, AndRHS)->isNullValue()) {
1860 // If the and is clearing all of the sign bits, change this to a
1861 // zero extension cast. To do this, cast the cast input to
1862 // unsigned, then to the requested size.
1863 Value *CastOp = CI->getOperand(0);
1865 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
1866 CI->getName()+".uns");
1867 NC = InsertNewInstBefore(NC, I);
1868 // Finally, insert a replacement for CI.
1869 NC = new CastInst(NC, CI->getType(), CI->getName());
1871 NC = InsertNewInstBefore(NC, I);
1872 WorkList.push_back(CI); // Delete CI later.
1873 I.setOperand(0, NC);
1874 return &I; // The AND operand was modified.
1881 // Try to fold constant and into select arguments.
1882 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1883 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1885 if (isa<PHINode>(Op0))
1886 if (Instruction *NV = FoldOpIntoPhi(I))
1890 Value *Op0NotVal = dyn_castNotVal(Op0);
1891 Value *Op1NotVal = dyn_castNotVal(Op1);
1893 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1894 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1896 // (~A & ~B) == (~(A | B)) - De Morgan's Law
1897 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1898 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
1899 I.getName()+".demorgan");
1900 InsertNewInstBefore(Or, I);
1901 return BinaryOperator::createNot(Or);
1904 if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
1905 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1906 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1909 Value *LHSVal, *RHSVal;
1910 ConstantInt *LHSCst, *RHSCst;
1911 Instruction::BinaryOps LHSCC, RHSCC;
1912 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1913 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1914 if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
1915 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1916 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1917 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1918 // Ensure that the larger constant is on the RHS.
1919 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1920 SetCondInst *LHS = cast<SetCondInst>(Op0);
1921 if (cast<ConstantBool>(Cmp)->getValue()) {
1922 std::swap(LHS, RHS);
1923 std::swap(LHSCst, RHSCst);
1924 std::swap(LHSCC, RHSCC);
1927 // At this point, we know we have have two setcc instructions
1928 // comparing a value against two constants and and'ing the result
1929 // together. Because of the above check, we know that we only have
1930 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1931 // FoldSetCCLogical check above), that the two constants are not
1933 assert(LHSCst != RHSCst && "Compares not folded above?");
1936 default: assert(0 && "Unknown integer condition code!");
1937 case Instruction::SetEQ:
1939 default: assert(0 && "Unknown integer condition code!");
1940 case Instruction::SetEQ: // (X == 13 & X == 15) -> false
1941 case Instruction::SetGT: // (X == 13 & X > 15) -> false
1942 return ReplaceInstUsesWith(I, ConstantBool::False);
1943 case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
1944 case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
1945 return ReplaceInstUsesWith(I, LHS);
1947 case Instruction::SetNE:
1949 default: assert(0 && "Unknown integer condition code!");
1950 case Instruction::SetLT:
1951 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
1952 return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
1953 break; // (X != 13 & X < 15) -> no change
1954 case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
1955 case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
1956 return ReplaceInstUsesWith(I, RHS);
1957 case Instruction::SetNE:
1958 if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
1959 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1960 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
1961 LHSVal->getName()+".off");
1962 InsertNewInstBefore(Add, I);
1963 const Type *UnsType = Add->getType()->getUnsignedVersion();
1964 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
1965 AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
1966 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1967 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1969 break; // (X != 13 & X != 15) -> no change
1972 case Instruction::SetLT:
1974 default: assert(0 && "Unknown integer condition code!");
1975 case Instruction::SetEQ: // (X < 13 & X == 15) -> false
1976 case Instruction::SetGT: // (X < 13 & X > 15) -> false
1977 return ReplaceInstUsesWith(I, ConstantBool::False);
1978 case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
1979 case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
1980 return ReplaceInstUsesWith(I, LHS);
1982 case Instruction::SetGT:
1984 default: assert(0 && "Unknown integer condition code!");
1985 case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
1986 return ReplaceInstUsesWith(I, LHS);
1987 case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
1988 return ReplaceInstUsesWith(I, RHS);
1989 case Instruction::SetNE:
1990 if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
1991 return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
1992 break; // (X > 13 & X != 15) -> no change
1993 case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
1994 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
2000 return Changed ? &I : 0;
2003 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
2004 bool Changed = SimplifyCommutative(I);
2005 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2007 if (isa<UndefValue>(Op1))
2008 return ReplaceInstUsesWith(I, // X | undef -> -1
2009 ConstantIntegral::getAllOnesValue(I.getType()));
2011 // or X, X = X or X, 0 == X
2012 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
2013 return ReplaceInstUsesWith(I, Op0);
2016 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2017 // If X is known to only contain bits that already exist in RHS, just
2018 // replace this instruction with RHS directly.
2019 if (MaskedValueIsZero(Op0,
2020 cast<ConstantIntegral>(ConstantExpr::getNot(RHS))))
2021 return ReplaceInstUsesWith(I, RHS);
2023 ConstantInt *C1; Value *X;
2024 // (X & C1) | C2 --> (X | C2) & (C1|C2)
2025 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
2026 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0->getName());
2028 InsertNewInstBefore(Or, I);
2029 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
2032 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
2033 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
2034 std::string Op0Name = Op0->getName(); Op0->setName("");
2035 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
2036 InsertNewInstBefore(Or, I);
2037 return BinaryOperator::createXor(Or,
2038 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
2041 // Try to fold constant and into select arguments.
2042 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2043 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2045 if (isa<PHINode>(Op0))
2046 if (Instruction *NV = FoldOpIntoPhi(I))
2050 Value *A, *B; ConstantInt *C1, *C2;
2052 if (match(Op0, m_And(m_Value(A), m_Value(B))))
2053 if (A == Op1 || B == Op1) // (A & ?) | A --> A
2054 return ReplaceInstUsesWith(I, Op1);
2055 if (match(Op1, m_And(m_Value(A), m_Value(B))))
2056 if (A == Op0 || B == Op0) // A | (A & ?) --> A
2057 return ReplaceInstUsesWith(I, Op0);
2059 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
2060 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2061 MaskedValueIsZero(Op1, C1)) {
2062 Instruction *NOr = BinaryOperator::createOr(A, Op1, Op0->getName());
2064 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2067 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
2068 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2069 MaskedValueIsZero(Op0, C1)) {
2070 Instruction *NOr = BinaryOperator::createOr(A, Op0, Op1->getName());
2072 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2075 // (A & C1)|(B & C2)
2076 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2077 match(Op1, m_And(m_Value(B), m_ConstantInt(C2)))) {
2079 if (A == B) // (A & C1)|(A & C2) == A & (C1|C2)
2080 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
2083 // If we have: ((V + N) & C1) | (V & C2)
2084 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
2085 // replace with V+N.
2086 if (C1 == ConstantExpr::getNot(C2)) {
2088 if ((C2->getRawValue() & (C2->getRawValue()+1)) == 0 && // C2 == 0+1+
2089 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
2090 // Add commutes, try both ways.
2091 if (V1 == B && MaskedValueIsZero(V2, C2))
2092 return ReplaceInstUsesWith(I, A);
2093 if (V2 == B && MaskedValueIsZero(V1, C2))
2094 return ReplaceInstUsesWith(I, A);
2096 // Or commutes, try both ways.
2097 if ((C1->getRawValue() & (C1->getRawValue()+1)) == 0 &&
2098 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
2099 // Add commutes, try both ways.
2100 if (V1 == A && MaskedValueIsZero(V2, C1))
2101 return ReplaceInstUsesWith(I, B);
2102 if (V2 == A && MaskedValueIsZero(V1, C1))
2103 return ReplaceInstUsesWith(I, B);
2108 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
2109 if (A == Op1) // ~A | A == -1
2110 return ReplaceInstUsesWith(I,
2111 ConstantIntegral::getAllOnesValue(I.getType()));
2115 // Note, A is still live here!
2116 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
2118 return ReplaceInstUsesWith(I,
2119 ConstantIntegral::getAllOnesValue(I.getType()));
2121 // (~A | ~B) == (~(A & B)) - De Morgan's Law
2122 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
2123 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
2124 I.getName()+".demorgan"), I);
2125 return BinaryOperator::createNot(And);
2129 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
2130 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
2131 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2134 Value *LHSVal, *RHSVal;
2135 ConstantInt *LHSCst, *RHSCst;
2136 Instruction::BinaryOps LHSCC, RHSCC;
2137 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
2138 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
2139 if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
2140 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
2141 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
2142 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
2143 // Ensure that the larger constant is on the RHS.
2144 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
2145 SetCondInst *LHS = cast<SetCondInst>(Op0);
2146 if (cast<ConstantBool>(Cmp)->getValue()) {
2147 std::swap(LHS, RHS);
2148 std::swap(LHSCst, RHSCst);
2149 std::swap(LHSCC, RHSCC);
2152 // At this point, we know we have have two setcc instructions
2153 // comparing a value against two constants and or'ing the result
2154 // together. Because of the above check, we know that we only have
2155 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
2156 // FoldSetCCLogical check above), that the two constants are not
2158 assert(LHSCst != RHSCst && "Compares not folded above?");
2161 default: assert(0 && "Unknown integer condition code!");
2162 case Instruction::SetEQ:
2164 default: assert(0 && "Unknown integer condition code!");
2165 case Instruction::SetEQ:
2166 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
2167 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2168 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
2169 LHSVal->getName()+".off");
2170 InsertNewInstBefore(Add, I);
2171 const Type *UnsType = Add->getType()->getUnsignedVersion();
2172 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
2173 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
2174 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2175 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
2177 break; // (X == 13 | X == 15) -> no change
2179 case Instruction::SetGT: // (X == 13 | X > 14) -> no change
2181 case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
2182 case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
2183 return ReplaceInstUsesWith(I, RHS);
2186 case Instruction::SetNE:
2188 default: assert(0 && "Unknown integer condition code!");
2189 case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
2190 case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
2191 return ReplaceInstUsesWith(I, LHS);
2192 case Instruction::SetNE: // (X != 13 | X != 15) -> true
2193 case Instruction::SetLT: // (X != 13 | X < 15) -> true
2194 return ReplaceInstUsesWith(I, ConstantBool::True);
2197 case Instruction::SetLT:
2199 default: assert(0 && "Unknown integer condition code!");
2200 case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
2202 case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
2203 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
2204 case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
2205 case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
2206 return ReplaceInstUsesWith(I, RHS);
2209 case Instruction::SetGT:
2211 default: assert(0 && "Unknown integer condition code!");
2212 case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
2213 case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
2214 return ReplaceInstUsesWith(I, LHS);
2215 case Instruction::SetNE: // (X > 13 | X != 15) -> true
2216 case Instruction::SetLT: // (X > 13 | X < 15) -> true
2217 return ReplaceInstUsesWith(I, ConstantBool::True);
2223 return Changed ? &I : 0;
2226 // XorSelf - Implements: X ^ X --> 0
2229 XorSelf(Value *rhs) : RHS(rhs) {}
2230 bool shouldApply(Value *LHS) const { return LHS == RHS; }
2231 Instruction *apply(BinaryOperator &Xor) const {
2237 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
2238 bool Changed = SimplifyCommutative(I);
2239 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2241 if (isa<UndefValue>(Op1))
2242 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
2244 // xor X, X = 0, even if X is nested in a sequence of Xor's.
2245 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
2246 assert(Result == &I && "AssociativeOpt didn't work?");
2247 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2250 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2252 if (RHS->isNullValue())
2253 return ReplaceInstUsesWith(I, Op0);
2255 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2256 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
2257 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
2258 if (RHS == ConstantBool::True && SCI->hasOneUse())
2259 return new SetCondInst(SCI->getInverseCondition(),
2260 SCI->getOperand(0), SCI->getOperand(1));
2262 // ~(c-X) == X-c-1 == X+(-c-1)
2263 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
2264 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
2265 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
2266 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
2267 ConstantInt::get(I.getType(), 1));
2268 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
2271 // ~(~X & Y) --> (X | ~Y)
2272 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
2273 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
2274 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
2276 BinaryOperator::createNot(Op0I->getOperand(1),
2277 Op0I->getOperand(1)->getName()+".not");
2278 InsertNewInstBefore(NotY, I);
2279 return BinaryOperator::createOr(Op0NotVal, NotY);
2283 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
2284 switch (Op0I->getOpcode()) {
2285 case Instruction::Add:
2286 // ~(X-c) --> (-c-1)-X
2287 if (RHS->isAllOnesValue()) {
2288 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
2289 return BinaryOperator::createSub(
2290 ConstantExpr::getSub(NegOp0CI,
2291 ConstantInt::get(I.getType(), 1)),
2292 Op0I->getOperand(0));
2295 case Instruction::And:
2296 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
2297 if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue())
2298 return BinaryOperator::createOr(Op0, RHS);
2300 case Instruction::Or:
2301 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
2302 if (ConstantExpr::getAnd(RHS, Op0CI) == RHS)
2303 return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS));
2309 // Try to fold constant and into select arguments.
2310 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2311 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2313 if (isa<PHINode>(Op0))
2314 if (Instruction *NV = FoldOpIntoPhi(I))
2318 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
2320 return ReplaceInstUsesWith(I,
2321 ConstantIntegral::getAllOnesValue(I.getType()));
2323 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
2325 return ReplaceInstUsesWith(I,
2326 ConstantIntegral::getAllOnesValue(I.getType()));
2328 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
2329 if (Op1I->getOpcode() == Instruction::Or) {
2330 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
2331 cast<BinaryOperator>(Op1I)->swapOperands();
2333 std::swap(Op0, Op1);
2334 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
2336 std::swap(Op0, Op1);
2338 } else if (Op1I->getOpcode() == Instruction::Xor) {
2339 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
2340 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
2341 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
2342 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
2345 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
2346 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
2347 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
2348 cast<BinaryOperator>(Op0I)->swapOperands();
2349 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
2350 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
2351 Op1->getName()+".not"), I);
2352 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
2354 } else if (Op0I->getOpcode() == Instruction::Xor) {
2355 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
2356 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2357 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
2358 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2361 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
2362 Value *A, *B; ConstantInt *C1, *C2;
2363 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2364 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) &&
2365 ConstantExpr::getAnd(C1, C2)->isNullValue())
2366 return BinaryOperator::createOr(Op0, Op1);
2368 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
2369 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
2370 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2373 return Changed ? &I : 0;
2376 /// MulWithOverflow - Compute Result = In1*In2, returning true if the result
2377 /// overflowed for this type.
2378 static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2380 Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
2381 return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
2384 static bool isPositive(ConstantInt *C) {
2385 return cast<ConstantSInt>(C)->getValue() >= 0;
2388 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
2389 /// overflowed for this type.
2390 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2392 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
2394 if (In1->getType()->isUnsigned())
2395 return cast<ConstantUInt>(Result)->getValue() <
2396 cast<ConstantUInt>(In1)->getValue();
2397 if (isPositive(In1) != isPositive(In2))
2399 if (isPositive(In1))
2400 return cast<ConstantSInt>(Result)->getValue() <
2401 cast<ConstantSInt>(In1)->getValue();
2402 return cast<ConstantSInt>(Result)->getValue() >
2403 cast<ConstantSInt>(In1)->getValue();
2406 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
2407 /// code necessary to compute the offset from the base pointer (without adding
2408 /// in the base pointer). Return the result as a signed integer of intptr size.
2409 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
2410 TargetData &TD = IC.getTargetData();
2411 gep_type_iterator GTI = gep_type_begin(GEP);
2412 const Type *UIntPtrTy = TD.getIntPtrType();
2413 const Type *SIntPtrTy = UIntPtrTy->getSignedVersion();
2414 Value *Result = Constant::getNullValue(SIntPtrTy);
2416 // Build a mask for high order bits.
2417 uint64_t PtrSizeMask = ~0ULL;
2418 PtrSizeMask >>= 64-(TD.getPointerSize()*8);
2420 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
2421 Value *Op = GEP->getOperand(i);
2422 uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask;
2423 Constant *Scale = ConstantExpr::getCast(ConstantUInt::get(UIntPtrTy, Size),
2425 if (Constant *OpC = dyn_cast<Constant>(Op)) {
2426 if (!OpC->isNullValue()) {
2427 OpC = ConstantExpr::getCast(OpC, SIntPtrTy);
2428 Scale = ConstantExpr::getMul(OpC, Scale);
2429 if (Constant *RC = dyn_cast<Constant>(Result))
2430 Result = ConstantExpr::getAdd(RC, Scale);
2432 // Emit an add instruction.
2433 Result = IC.InsertNewInstBefore(
2434 BinaryOperator::createAdd(Result, Scale,
2435 GEP->getName()+".offs"), I);
2439 // Convert to correct type.
2440 Op = IC.InsertNewInstBefore(new CastInst(Op, SIntPtrTy,
2441 Op->getName()+".c"), I);
2443 // We'll let instcombine(mul) convert this to a shl if possible.
2444 Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
2445 GEP->getName()+".idx"), I);
2447 // Emit an add instruction.
2448 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
2449 GEP->getName()+".offs"), I);
2455 /// FoldGEPSetCC - Fold comparisons between a GEP instruction and something
2456 /// else. At this point we know that the GEP is on the LHS of the comparison.
2457 Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS,
2458 Instruction::BinaryOps Cond,
2460 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
2462 if (CastInst *CI = dyn_cast<CastInst>(RHS))
2463 if (isa<PointerType>(CI->getOperand(0)->getType()))
2464 RHS = CI->getOperand(0);
2466 Value *PtrBase = GEPLHS->getOperand(0);
2467 if (PtrBase == RHS) {
2468 // As an optimization, we don't actually have to compute the actual value of
2469 // OFFSET if this is a seteq or setne comparison, just return whether each
2470 // index is zero or not.
2471 if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) {
2472 Instruction *InVal = 0;
2473 gep_type_iterator GTI = gep_type_begin(GEPLHS);
2474 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
2476 if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
2477 if (isa<UndefValue>(C)) // undef index -> undef.
2478 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
2479 if (C->isNullValue())
2481 else if (TD->getTypeSize(GTI.getIndexedType()) == 0) {
2482 EmitIt = false; // This is indexing into a zero sized array?
2483 } else if (isa<ConstantInt>(C))
2484 return ReplaceInstUsesWith(I, // No comparison is needed here.
2485 ConstantBool::get(Cond == Instruction::SetNE));
2490 new SetCondInst(Cond, GEPLHS->getOperand(i),
2491 Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
2495 InVal = InsertNewInstBefore(InVal, I);
2496 InsertNewInstBefore(Comp, I);
2497 if (Cond == Instruction::SetNE) // True if any are unequal
2498 InVal = BinaryOperator::createOr(InVal, Comp);
2499 else // True if all are equal
2500 InVal = BinaryOperator::createAnd(InVal, Comp);
2508 ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0
2509 ConstantBool::get(Cond == Instruction::SetEQ));
2512 // Only lower this if the setcc is the only user of the GEP or if we expect
2513 // the result to fold to a constant!
2514 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
2515 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
2516 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
2517 return new SetCondInst(Cond, Offset,
2518 Constant::getNullValue(Offset->getType()));
2520 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
2521 // If the base pointers are different, but the indices are the same, just
2522 // compare the base pointer.
2523 if (PtrBase != GEPRHS->getOperand(0)) {
2524 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
2525 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
2526 GEPRHS->getOperand(0)->getType();
2528 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2529 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2530 IndicesTheSame = false;
2534 // If all indices are the same, just compare the base pointers.
2536 return new SetCondInst(Cond, GEPLHS->getOperand(0),
2537 GEPRHS->getOperand(0));
2539 // Otherwise, the base pointers are different and the indices are
2540 // different, bail out.
2544 // If one of the GEPs has all zero indices, recurse.
2545 bool AllZeros = true;
2546 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2547 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
2548 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
2553 return FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0),
2554 SetCondInst::getSwappedCondition(Cond), I);
2556 // If the other GEP has all zero indices, recurse.
2558 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2559 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
2560 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
2565 return FoldGEPSetCC(GEPLHS, GEPRHS->getOperand(0), Cond, I);
2567 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
2568 // If the GEPs only differ by one index, compare it.
2569 unsigned NumDifferences = 0; // Keep track of # differences.
2570 unsigned DiffOperand = 0; // The operand that differs.
2571 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2572 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2573 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
2574 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
2575 // Irreconcilable differences.
2579 if (NumDifferences++) break;
2584 if (NumDifferences == 0) // SAME GEP?
2585 return ReplaceInstUsesWith(I, // No comparison is needed here.
2586 ConstantBool::get(Cond == Instruction::SetEQ));
2587 else if (NumDifferences == 1) {
2588 Value *LHSV = GEPLHS->getOperand(DiffOperand);
2589 Value *RHSV = GEPRHS->getOperand(DiffOperand);
2591 // Convert the operands to signed values to make sure to perform a
2592 // signed comparison.
2593 const Type *NewTy = LHSV->getType()->getSignedVersion();
2594 if (LHSV->getType() != NewTy)
2595 LHSV = InsertNewInstBefore(new CastInst(LHSV, NewTy,
2596 LHSV->getName()), I);
2597 if (RHSV->getType() != NewTy)
2598 RHSV = InsertNewInstBefore(new CastInst(RHSV, NewTy,
2599 RHSV->getName()), I);
2600 return new SetCondInst(Cond, LHSV, RHSV);
2604 // Only lower this if the setcc is the only user of the GEP or if we expect
2605 // the result to fold to a constant!
2606 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
2607 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
2608 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
2609 Value *L = EmitGEPOffset(GEPLHS, I, *this);
2610 Value *R = EmitGEPOffset(GEPRHS, I, *this);
2611 return new SetCondInst(Cond, L, R);
2618 Instruction *InstCombiner::visitSetCondInst(SetCondInst &I) {
2619 bool Changed = SimplifyCommutative(I);
2620 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2621 const Type *Ty = Op0->getType();
2625 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
2627 if (isa<UndefValue>(Op1)) // X setcc undef -> undef
2628 return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
2630 // setcc <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
2631 // addresses never equal each other! We already know that Op0 != Op1.
2632 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
2633 isa<ConstantPointerNull>(Op0)) &&
2634 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
2635 isa<ConstantPointerNull>(Op1)))
2636 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
2638 // setcc's with boolean values can always be turned into bitwise operations
2639 if (Ty == Type::BoolTy) {
2640 switch (I.getOpcode()) {
2641 default: assert(0 && "Invalid setcc instruction!");
2642 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
2643 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
2644 InsertNewInstBefore(Xor, I);
2645 return BinaryOperator::createNot(Xor);
2647 case Instruction::SetNE:
2648 return BinaryOperator::createXor(Op0, Op1);
2650 case Instruction::SetGT:
2651 std::swap(Op0, Op1); // Change setgt -> setlt
2653 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
2654 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2655 InsertNewInstBefore(Not, I);
2656 return BinaryOperator::createAnd(Not, Op1);
2658 case Instruction::SetGE:
2659 std::swap(Op0, Op1); // Change setge -> setle
2661 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
2662 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2663 InsertNewInstBefore(Not, I);
2664 return BinaryOperator::createOr(Not, Op1);
2669 // See if we are doing a comparison between a constant and an instruction that
2670 // can be folded into the comparison.
2671 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2672 // Check to see if we are comparing against the minimum or maximum value...
2673 if (CI->isMinValue()) {
2674 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
2675 return ReplaceInstUsesWith(I, ConstantBool::False);
2676 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
2677 return ReplaceInstUsesWith(I, ConstantBool::True);
2678 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
2679 return BinaryOperator::createSetEQ(Op0, Op1);
2680 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
2681 return BinaryOperator::createSetNE(Op0, Op1);
2683 } else if (CI->isMaxValue()) {
2684 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
2685 return ReplaceInstUsesWith(I, ConstantBool::False);
2686 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
2687 return ReplaceInstUsesWith(I, ConstantBool::True);
2688 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
2689 return BinaryOperator::createSetEQ(Op0, Op1);
2690 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
2691 return BinaryOperator::createSetNE(Op0, Op1);
2693 // Comparing against a value really close to min or max?
2694 } else if (isMinValuePlusOne(CI)) {
2695 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
2696 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
2697 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
2698 return BinaryOperator::createSetNE(Op0, SubOne(CI));
2700 } else if (isMaxValueMinusOne(CI)) {
2701 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
2702 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
2703 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
2704 return BinaryOperator::createSetNE(Op0, AddOne(CI));
2707 // If we still have a setle or setge instruction, turn it into the
2708 // appropriate setlt or setgt instruction. Since the border cases have
2709 // already been handled above, this requires little checking.
2711 if (I.getOpcode() == Instruction::SetLE)
2712 return BinaryOperator::createSetLT(Op0, AddOne(CI));
2713 if (I.getOpcode() == Instruction::SetGE)
2714 return BinaryOperator::createSetGT(Op0, SubOne(CI));
2716 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
2717 switch (LHSI->getOpcode()) {
2718 case Instruction::And:
2719 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
2720 LHSI->getOperand(0)->hasOneUse()) {
2721 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
2722 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
2723 // happens a LOT in code produced by the C front-end, for bitfield
2725 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
2726 ConstantUInt *ShAmt;
2727 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
2728 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
2729 const Type *Ty = LHSI->getType();
2731 // We can fold this as long as we can't shift unknown bits
2732 // into the mask. This can only happen with signed shift
2733 // rights, as they sign-extend.
2735 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
2736 Shift->getType()->isUnsigned();
2738 // To test for the bad case of the signed shr, see if any
2739 // of the bits shifted in could be tested after the mask.
2740 int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue();
2741 if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
2743 Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal);
2745 ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
2746 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
2752 if (Shift->getOpcode() == Instruction::Shl)
2753 NewCst = ConstantExpr::getUShr(CI, ShAmt);
2755 NewCst = ConstantExpr::getShl(CI, ShAmt);
2757 // Check to see if we are shifting out any of the bits being
2759 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
2760 // If we shifted bits out, the fold is not going to work out.
2761 // As a special case, check to see if this means that the
2762 // result is always true or false now.
2763 if (I.getOpcode() == Instruction::SetEQ)
2764 return ReplaceInstUsesWith(I, ConstantBool::False);
2765 if (I.getOpcode() == Instruction::SetNE)
2766 return ReplaceInstUsesWith(I, ConstantBool::True);
2768 I.setOperand(1, NewCst);
2769 Constant *NewAndCST;
2770 if (Shift->getOpcode() == Instruction::Shl)
2771 NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
2773 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
2774 LHSI->setOperand(1, NewAndCST);
2775 LHSI->setOperand(0, Shift->getOperand(0));
2776 WorkList.push_back(Shift); // Shift is dead.
2777 AddUsesToWorkList(I);
2785 case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
2786 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2787 switch (I.getOpcode()) {
2789 case Instruction::SetEQ:
2790 case Instruction::SetNE: {
2791 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2793 // Check that the shift amount is in range. If not, don't perform
2794 // undefined shifts. When the shift is visited it will be
2796 if (ShAmt->getValue() >= TypeBits)
2799 // If we are comparing against bits always shifted out, the
2800 // comparison cannot succeed.
2802 ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
2803 if (Comp != CI) {// Comparing against a bit that we know is zero.
2804 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2805 Constant *Cst = ConstantBool::get(IsSetNE);
2806 return ReplaceInstUsesWith(I, Cst);
2809 if (LHSI->hasOneUse()) {
2810 // Otherwise strength reduce the shift into an and.
2811 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2812 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
2815 if (CI->getType()->isUnsigned()) {
2816 Mask = ConstantUInt::get(CI->getType(), Val);
2817 } else if (ShAmtVal != 0) {
2818 Mask = ConstantSInt::get(CI->getType(), Val);
2820 Mask = ConstantInt::getAllOnesValue(CI->getType());
2824 BinaryOperator::createAnd(LHSI->getOperand(0),
2825 Mask, LHSI->getName()+".mask");
2826 Value *And = InsertNewInstBefore(AndI, I);
2827 return new SetCondInst(I.getOpcode(), And,
2828 ConstantExpr::getUShr(CI, ShAmt));
2835 case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
2836 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2837 switch (I.getOpcode()) {
2839 case Instruction::SetEQ:
2840 case Instruction::SetNE: {
2842 // Check that the shift amount is in range. If not, don't perform
2843 // undefined shifts. When the shift is visited it will be
2845 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2846 if (ShAmt->getValue() >= TypeBits)
2849 // If we are comparing against bits always shifted out, the
2850 // comparison cannot succeed.
2852 ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
2854 if (Comp != CI) {// Comparing against a bit that we know is zero.
2855 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2856 Constant *Cst = ConstantBool::get(IsSetNE);
2857 return ReplaceInstUsesWith(I, Cst);
2860 if (LHSI->hasOneUse() || CI->isNullValue()) {
2861 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2863 // Otherwise strength reduce the shift into an and.
2864 uint64_t Val = ~0ULL; // All ones.
2865 Val <<= ShAmtVal; // Shift over to the right spot.
2868 if (CI->getType()->isUnsigned()) {
2869 Val &= ~0ULL >> (64-TypeBits);
2870 Mask = ConstantUInt::get(CI->getType(), Val);
2872 Mask = ConstantSInt::get(CI->getType(), Val);
2876 BinaryOperator::createAnd(LHSI->getOperand(0),
2877 Mask, LHSI->getName()+".mask");
2878 Value *And = InsertNewInstBefore(AndI, I);
2879 return new SetCondInst(I.getOpcode(), And,
2880 ConstantExpr::getShl(CI, ShAmt));
2888 case Instruction::Div:
2889 // Fold: (div X, C1) op C2 -> range check
2890 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
2891 // Fold this div into the comparison, producing a range check.
2892 // Determine, based on the divide type, what the range is being
2893 // checked. If there is an overflow on the low or high side, remember
2894 // it, otherwise compute the range [low, hi) bounding the new value.
2895 bool LoOverflow = false, HiOverflow = 0;
2896 ConstantInt *LoBound = 0, *HiBound = 0;
2899 bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
2901 Instruction::BinaryOps Opcode = I.getOpcode();
2903 if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
2904 } else if (LHSI->getType()->isUnsigned()) { // udiv
2906 LoOverflow = ProdOV;
2907 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
2908 } else if (isPositive(DivRHS)) { // Divisor is > 0.
2909 if (CI->isNullValue()) { // (X / pos) op 0
2911 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
2913 } else if (isPositive(CI)) { // (X / pos) op pos
2915 LoOverflow = ProdOV;
2916 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
2917 } else { // (X / pos) op neg
2918 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
2919 LoOverflow = AddWithOverflow(LoBound, Prod,
2920 cast<ConstantInt>(DivRHSH));
2922 HiOverflow = ProdOV;
2924 } else { // Divisor is < 0.
2925 if (CI->isNullValue()) { // (X / neg) op 0
2926 LoBound = AddOne(DivRHS);
2927 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
2928 if (HiBound == DivRHS)
2929 LoBound = 0; // - INTMIN = INTMIN
2930 } else if (isPositive(CI)) { // (X / neg) op pos
2931 HiOverflow = LoOverflow = ProdOV;
2933 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
2934 HiBound = AddOne(Prod);
2935 } else { // (X / neg) op neg
2937 LoOverflow = HiOverflow = ProdOV;
2938 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
2941 // Dividing by a negate swaps the condition.
2942 Opcode = SetCondInst::getSwappedCondition(Opcode);
2946 Value *X = LHSI->getOperand(0);
2948 default: assert(0 && "Unhandled setcc opcode!");
2949 case Instruction::SetEQ:
2950 if (LoOverflow && HiOverflow)
2951 return ReplaceInstUsesWith(I, ConstantBool::False);
2952 else if (HiOverflow)
2953 return new SetCondInst(Instruction::SetGE, X, LoBound);
2954 else if (LoOverflow)
2955 return new SetCondInst(Instruction::SetLT, X, HiBound);
2957 return InsertRangeTest(X, LoBound, HiBound, true, I);
2958 case Instruction::SetNE:
2959 if (LoOverflow && HiOverflow)
2960 return ReplaceInstUsesWith(I, ConstantBool::True);
2961 else if (HiOverflow)
2962 return new SetCondInst(Instruction::SetLT, X, LoBound);
2963 else if (LoOverflow)
2964 return new SetCondInst(Instruction::SetGE, X, HiBound);
2966 return InsertRangeTest(X, LoBound, HiBound, false, I);
2967 case Instruction::SetLT:
2969 return ReplaceInstUsesWith(I, ConstantBool::False);
2970 return new SetCondInst(Instruction::SetLT, X, LoBound);
2971 case Instruction::SetGT:
2973 return ReplaceInstUsesWith(I, ConstantBool::False);
2974 return new SetCondInst(Instruction::SetGE, X, HiBound);
2981 // Simplify seteq and setne instructions...
2982 if (I.getOpcode() == Instruction::SetEQ ||
2983 I.getOpcode() == Instruction::SetNE) {
2984 bool isSetNE = I.getOpcode() == Instruction::SetNE;
2986 // If the first operand is (and|or|xor) with a constant, and the second
2987 // operand is a constant, simplify a bit.
2988 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
2989 switch (BO->getOpcode()) {
2990 case Instruction::Rem:
2991 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
2992 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
2994 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1) {
2995 int64_t V = cast<ConstantSInt>(BO->getOperand(1))->getValue();
2996 if (isPowerOf2_64(V)) {
2997 unsigned L2 = Log2_64(V);
2998 const Type *UTy = BO->getType()->getUnsignedVersion();
2999 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
3001 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
3002 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
3003 RHSCst, BO->getName()), I);
3004 return BinaryOperator::create(I.getOpcode(), NewRem,
3005 Constant::getNullValue(UTy));
3010 case Instruction::Add:
3011 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
3012 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3013 if (BO->hasOneUse())
3014 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
3015 ConstantExpr::getSub(CI, BOp1C));
3016 } else if (CI->isNullValue()) {
3017 // Replace ((add A, B) != 0) with (A != -B) if A or B is
3018 // efficiently invertible, or if the add has just this one use.
3019 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
3021 if (Value *NegVal = dyn_castNegVal(BOp1))
3022 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
3023 else if (Value *NegVal = dyn_castNegVal(BOp0))
3024 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
3025 else if (BO->hasOneUse()) {
3026 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
3028 InsertNewInstBefore(Neg, I);
3029 return new SetCondInst(I.getOpcode(), BOp0, Neg);
3033 case Instruction::Xor:
3034 // For the xor case, we can xor two constants together, eliminating
3035 // the explicit xor.
3036 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
3037 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
3038 ConstantExpr::getXor(CI, BOC));
3041 case Instruction::Sub:
3042 // Replace (([sub|xor] A, B) != 0) with (A != B)
3043 if (CI->isNullValue())
3044 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
3048 case Instruction::Or:
3049 // If bits are being or'd in that are not present in the constant we
3050 // are comparing against, then the comparison could never succeed!
3051 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
3052 Constant *NotCI = ConstantExpr::getNot(CI);
3053 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
3054 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3058 case Instruction::And:
3059 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3060 // If bits are being compared against that are and'd out, then the
3061 // comparison can never succeed!
3062 if (!ConstantExpr::getAnd(CI,
3063 ConstantExpr::getNot(BOC))->isNullValue())
3064 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3066 // If we have ((X & C) == C), turn it into ((X & C) != 0).
3067 if (CI == BOC && isOneBitSet(CI))
3068 return new SetCondInst(isSetNE ? Instruction::SetEQ :
3069 Instruction::SetNE, Op0,
3070 Constant::getNullValue(CI->getType()));
3072 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
3073 // to be a signed value as appropriate.
3074 if (isSignBit(BOC)) {
3075 Value *X = BO->getOperand(0);
3076 // If 'X' is not signed, insert a cast now...
3077 if (!BOC->getType()->isSigned()) {
3078 const Type *DestTy = BOC->getType()->getSignedVersion();
3079 X = InsertCastBefore(X, DestTy, I);
3081 return new SetCondInst(isSetNE ? Instruction::SetLT :
3082 Instruction::SetGE, X,
3083 Constant::getNullValue(X->getType()));
3086 // ((X & ~7) == 0) --> X < 8
3087 if (CI->isNullValue() && isHighOnes(BOC)) {
3088 Value *X = BO->getOperand(0);
3089 Constant *NegX = ConstantExpr::getNeg(BOC);
3091 // If 'X' is signed, insert a cast now.
3092 if (NegX->getType()->isSigned()) {
3093 const Type *DestTy = NegX->getType()->getUnsignedVersion();
3094 X = InsertCastBefore(X, DestTy, I);
3095 NegX = ConstantExpr::getCast(NegX, DestTy);
3098 return new SetCondInst(isSetNE ? Instruction::SetGE :
3099 Instruction::SetLT, X, NegX);
3106 } else { // Not a SetEQ/SetNE
3107 // If the LHS is a cast from an integral value of the same size,
3108 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
3109 Value *CastOp = Cast->getOperand(0);
3110 const Type *SrcTy = CastOp->getType();
3111 unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits();
3112 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
3113 SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
3114 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
3115 "Source and destination signednesses should differ!");
3116 if (Cast->getType()->isSigned()) {
3117 // If this is a signed comparison, check for comparisons in the
3118 // vicinity of zero.
3119 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
3121 return BinaryOperator::createSetGT(CastOp,
3122 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize-1))-1));
3123 else if (I.getOpcode() == Instruction::SetGT &&
3124 cast<ConstantSInt>(CI)->getValue() == -1)
3125 // X > -1 => x < 128
3126 return BinaryOperator::createSetLT(CastOp,
3127 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize-1)));
3129 ConstantUInt *CUI = cast<ConstantUInt>(CI);
3130 if (I.getOpcode() == Instruction::SetLT &&
3131 CUI->getValue() == 1ULL << (SrcTySize-1))
3132 // X < 128 => X > -1
3133 return BinaryOperator::createSetGT(CastOp,
3134 ConstantSInt::get(SrcTy, -1));
3135 else if (I.getOpcode() == Instruction::SetGT &&
3136 CUI->getValue() == (1ULL << (SrcTySize-1))-1)
3138 return BinaryOperator::createSetLT(CastOp,
3139 Constant::getNullValue(SrcTy));
3146 // Handle setcc with constant RHS's that can be integer, FP or pointer.
3147 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
3148 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3149 switch (LHSI->getOpcode()) {
3150 case Instruction::GetElementPtr:
3151 if (RHSC->isNullValue()) {
3152 // Transform setcc GEP P, int 0, int 0, int 0, null -> setcc P, null
3153 bool isAllZeros = true;
3154 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
3155 if (!isa<Constant>(LHSI->getOperand(i)) ||
3156 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
3161 return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),
3162 Constant::getNullValue(LHSI->getOperand(0)->getType()));
3166 case Instruction::PHI:
3167 if (Instruction *NV = FoldOpIntoPhi(I))
3170 case Instruction::Select:
3171 // If either operand of the select is a constant, we can fold the
3172 // comparison into the select arms, which will cause one to be
3173 // constant folded and the select turned into a bitwise or.
3174 Value *Op1 = 0, *Op2 = 0;
3175 if (LHSI->hasOneUse()) {
3176 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
3177 // Fold the known value into the constant operand.
3178 Op1 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3179 // Insert a new SetCC of the other select operand.
3180 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3181 LHSI->getOperand(2), RHSC,
3183 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
3184 // Fold the known value into the constant operand.
3185 Op2 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3186 // Insert a new SetCC of the other select operand.
3187 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3188 LHSI->getOperand(1), RHSC,
3194 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
3199 // If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now.
3200 if (User *GEP = dyn_castGetElementPtr(Op0))
3201 if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I))
3203 if (User *GEP = dyn_castGetElementPtr(Op1))
3204 if (Instruction *NI = FoldGEPSetCC(GEP, Op0,
3205 SetCondInst::getSwappedCondition(I.getOpcode()), I))
3208 // Test to see if the operands of the setcc are casted versions of other
3209 // values. If the cast can be stripped off both arguments, we do so now.
3210 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3211 Value *CastOp0 = CI->getOperand(0);
3212 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
3213 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
3214 (I.getOpcode() == Instruction::SetEQ ||
3215 I.getOpcode() == Instruction::SetNE)) {
3216 // We keep moving the cast from the left operand over to the right
3217 // operand, where it can often be eliminated completely.
3220 // If operand #1 is a cast instruction, see if we can eliminate it as
3222 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
3223 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
3225 Op1 = CI2->getOperand(0);
3227 // If Op1 is a constant, we can fold the cast into the constant.
3228 if (Op1->getType() != Op0->getType())
3229 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
3230 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
3232 // Otherwise, cast the RHS right before the setcc
3233 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
3234 InsertNewInstBefore(cast<Instruction>(Op1), I);
3236 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
3239 // Handle the special case of: setcc (cast bool to X), <cst>
3240 // This comes up when you have code like
3243 // For generality, we handle any zero-extension of any operand comparison
3244 // with a constant or another cast from the same type.
3245 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
3246 if (Instruction *R = visitSetCondInstWithCastAndCast(I))
3249 return Changed ? &I : 0;
3252 // visitSetCondInstWithCastAndCast - Handle setcond (cast x to y), (cast/cst).
3253 // We only handle extending casts so far.
3255 Instruction *InstCombiner::visitSetCondInstWithCastAndCast(SetCondInst &SCI) {
3256 Value *LHSCIOp = cast<CastInst>(SCI.getOperand(0))->getOperand(0);
3257 const Type *SrcTy = LHSCIOp->getType();
3258 const Type *DestTy = SCI.getOperand(0)->getType();
3261 if (!DestTy->isIntegral() || !SrcTy->isIntegral())
3264 unsigned SrcBits = SrcTy->getPrimitiveSizeInBits();
3265 unsigned DestBits = DestTy->getPrimitiveSizeInBits();
3266 if (SrcBits >= DestBits) return 0; // Only handle extending cast.
3268 // Is this a sign or zero extension?
3269 bool isSignSrc = SrcTy->isSigned();
3270 bool isSignDest = DestTy->isSigned();
3272 if (CastInst *CI = dyn_cast<CastInst>(SCI.getOperand(1))) {
3273 // Not an extension from the same type?
3274 RHSCIOp = CI->getOperand(0);
3275 if (RHSCIOp->getType() != LHSCIOp->getType()) return 0;
3276 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(SCI.getOperand(1))) {
3277 // Compute the constant that would happen if we truncated to SrcTy then
3278 // reextended to DestTy.
3279 Constant *Res = ConstantExpr::getCast(CI, SrcTy);
3281 if (ConstantExpr::getCast(Res, DestTy) == CI) {
3284 // If the value cannot be represented in the shorter type, we cannot emit
3285 // a simple comparison.
3286 if (SCI.getOpcode() == Instruction::SetEQ)
3287 return ReplaceInstUsesWith(SCI, ConstantBool::False);
3288 if (SCI.getOpcode() == Instruction::SetNE)
3289 return ReplaceInstUsesWith(SCI, ConstantBool::True);
3291 // Evaluate the comparison for LT.
3293 if (DestTy->isSigned()) {
3294 // We're performing a signed comparison.
3296 // Signed extend and signed comparison.
3297 if (cast<ConstantSInt>(CI)->getValue() < 0) // X < (small) --> false
3298 Result = ConstantBool::False;
3300 Result = ConstantBool::True; // X < (large) --> true
3302 // Unsigned extend and signed comparison.
3303 if (cast<ConstantSInt>(CI)->getValue() < 0)
3304 Result = ConstantBool::False;
3306 Result = ConstantBool::True;
3309 // We're performing an unsigned comparison.
3311 // Unsigned extend & compare -> always true.
3312 Result = ConstantBool::True;
3314 // We're performing an unsigned comp with a sign extended value.
3315 // This is true if the input is >= 0. [aka >s -1]
3316 Constant *NegOne = ConstantIntegral::getAllOnesValue(SrcTy);
3317 Result = InsertNewInstBefore(BinaryOperator::createSetGT(LHSCIOp,
3318 NegOne, SCI.getName()), SCI);
3322 // Finally, return the value computed.
3323 if (SCI.getOpcode() == Instruction::SetLT) {
3324 return ReplaceInstUsesWith(SCI, Result);
3326 assert(SCI.getOpcode()==Instruction::SetGT &&"SetCC should be folded!");
3327 if (Constant *CI = dyn_cast<Constant>(Result))
3328 return ReplaceInstUsesWith(SCI, ConstantExpr::getNot(CI));
3330 return BinaryOperator::createNot(Result);
3337 // Okay, just insert a compare of the reduced operands now!
3338 return BinaryOperator::create(SCI.getOpcode(), LHSCIOp, RHSCIOp);
3341 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
3342 assert(I.getOperand(1)->getType() == Type::UByteTy);
3343 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3344 bool isLeftShift = I.getOpcode() == Instruction::Shl;
3346 // shl X, 0 == X and shr X, 0 == X
3347 // shl 0, X == 0 and shr 0, X == 0
3348 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
3349 Op0 == Constant::getNullValue(Op0->getType()))
3350 return ReplaceInstUsesWith(I, Op0);
3352 if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
3353 if (!isLeftShift && I.getType()->isSigned())
3354 return ReplaceInstUsesWith(I, Op0);
3355 else // undef << X -> 0 AND undef >>u X -> 0
3356 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3358 if (isa<UndefValue>(Op1)) {
3359 if (isLeftShift || I.getType()->isUnsigned())// X << undef, X >>u undef -> 0
3360 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3362 return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X
3365 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
3367 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
3368 if (CSI->isAllOnesValue())
3369 return ReplaceInstUsesWith(I, CSI);
3371 // Try to fold constant and into select arguments.
3372 if (isa<Constant>(Op0))
3373 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
3374 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3377 // See if we can turn a signed shr into an unsigned shr.
3378 if (!isLeftShift && I.getType()->isSigned()) {
3379 if (MaskedValueIsZero(Op0, ConstantInt::getMinValue(I.getType()))) {
3380 Value *V = InsertCastBefore(Op0, I.getType()->getUnsignedVersion(), I);
3381 V = InsertNewInstBefore(new ShiftInst(Instruction::Shr, V, Op1,
3383 return new CastInst(V, I.getType());
3387 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
3388 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
3389 // of a signed value.
3391 unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits();
3392 if (CUI->getValue() >= TypeBits) {
3393 if (!Op0->getType()->isSigned() || isLeftShift)
3394 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
3396 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
3401 // ((X*C1) << C2) == (X * (C1 << C2))
3402 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
3403 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
3404 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
3405 return BinaryOperator::createMul(BO->getOperand(0),
3406 ConstantExpr::getShl(BOOp, CUI));
3408 // Try to fold constant and into select arguments.
3409 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3410 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3412 if (isa<PHINode>(Op0))
3413 if (Instruction *NV = FoldOpIntoPhi(I))
3416 if (Op0->hasOneUse()) {
3417 // If this is a SHL of a sign-extending cast, see if we can turn the input
3418 // into a zero extending cast (a simple strength reduction).
3419 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3420 const Type *SrcTy = CI->getOperand(0)->getType();
3421 if (isLeftShift && SrcTy->isInteger() && SrcTy->isSigned() &&
3422 SrcTy->getPrimitiveSizeInBits() <
3423 CI->getType()->getPrimitiveSizeInBits()) {
3424 // We can change it to a zero extension if we are shifting out all of
3425 // the sign extended bits. To check this, form a mask of all of the
3426 // sign extend bits, then shift them left and see if we have anything
3428 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); // 1111
3429 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); // 00001111
3430 Mask = ConstantExpr::getNot(Mask); // 1's in the sign bits: 11110000
3431 if (ConstantExpr::getShl(Mask, CUI)->isNullValue()) {
3432 // If the shift is nuking all of the sign bits, change this to a
3433 // zero extension cast. To do this, cast the cast input to
3434 // unsigned, then to the requested size.
3435 Value *CastOp = CI->getOperand(0);
3437 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
3438 CI->getName()+".uns");
3439 NC = InsertNewInstBefore(NC, I);
3440 // Finally, insert a replacement for CI.
3441 NC = new CastInst(NC, CI->getType(), CI->getName());
3443 NC = InsertNewInstBefore(NC, I);
3444 WorkList.push_back(CI); // Delete CI later.
3445 I.setOperand(0, NC);
3446 return &I; // The SHL operand was modified.
3451 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
3452 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
3455 switch (Op0BO->getOpcode()) {
3457 case Instruction::Add:
3458 case Instruction::And:
3459 case Instruction::Or:
3460 case Instruction::Xor:
3461 // These operators commute.
3462 // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
3463 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
3464 match(Op0BO->getOperand(1),
3465 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == CUI) {
3466 Instruction *YS = new ShiftInst(Instruction::Shl,
3467 Op0BO->getOperand(0), CUI,
3469 InsertNewInstBefore(YS, I); // (Y << C)
3470 Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
3472 Op0BO->getOperand(1)->getName());
3473 InsertNewInstBefore(X, I); // (X + (Y << C))
3474 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
3475 C2 = ConstantExpr::getShl(C2, CUI);
3476 return BinaryOperator::createAnd(X, C2);
3479 // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
3480 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
3481 match(Op0BO->getOperand(1),
3482 m_And(m_Shr(m_Value(V1), m_Value(V2)),
3483 m_ConstantInt(CC))) && V2 == CUI &&
3484 cast<BinaryOperator>(Op0BO->getOperand(1))->getOperand(0)->hasOneUse()) {
3485 Instruction *YS = new ShiftInst(Instruction::Shl,
3486 Op0BO->getOperand(0), CUI,
3488 InsertNewInstBefore(YS, I); // (Y << C)
3490 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, CUI),
3491 V1->getName()+".mask");
3492 InsertNewInstBefore(XM, I); // X & (CC << C)
3494 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
3498 case Instruction::Sub:
3499 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
3500 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
3501 match(Op0BO->getOperand(0),
3502 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == CUI) {
3503 Instruction *YS = new ShiftInst(Instruction::Shl,
3504 Op0BO->getOperand(1), CUI,
3506 InsertNewInstBefore(YS, I); // (Y << C)
3507 Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
3509 Op0BO->getOperand(0)->getName());
3510 InsertNewInstBefore(X, I); // (X + (Y << C))
3511 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
3512 C2 = ConstantExpr::getShl(C2, CUI);
3513 return BinaryOperator::createAnd(X, C2);
3516 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
3517 match(Op0BO->getOperand(0),
3518 m_And(m_Shr(m_Value(V1), m_Value(V2)),
3519 m_ConstantInt(CC))) && V2 == CUI &&
3520 cast<BinaryOperator>(Op0BO->getOperand(0))->getOperand(0)->hasOneUse()) {
3521 Instruction *YS = new ShiftInst(Instruction::Shl,
3522 Op0BO->getOperand(1), CUI,
3524 InsertNewInstBefore(YS, I); // (Y << C)
3526 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, CUI),
3527 V1->getName()+".mask");
3528 InsertNewInstBefore(XM, I); // X & (CC << C)
3530 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
3537 // If the operand is an bitwise operator with a constant RHS, and the
3538 // shift is the only use, we can pull it out of the shift.
3539 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
3540 bool isValid = true; // Valid only for And, Or, Xor
3541 bool highBitSet = false; // Transform if high bit of constant set?
3543 switch (Op0BO->getOpcode()) {
3544 default: isValid = false; break; // Do not perform transform!
3545 case Instruction::Add:
3546 isValid = isLeftShift;
3548 case Instruction::Or:
3549 case Instruction::Xor:
3552 case Instruction::And:
3557 // If this is a signed shift right, and the high bit is modified
3558 // by the logical operation, do not perform the transformation.
3559 // The highBitSet boolean indicates the value of the high bit of
3560 // the constant which would cause it to be modified for this
3563 if (isValid && !isLeftShift && !I.getType()->isUnsigned()) {
3564 uint64_t Val = Op0C->getRawValue();
3565 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
3569 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI);
3571 Instruction *NewShift =
3572 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI,
3575 InsertNewInstBefore(NewShift, I);
3577 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
3584 // If this is a shift of a shift, see if we can fold the two together...
3585 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
3586 if (ConstantUInt *ShiftAmt1C =
3587 dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) {
3588 unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getValue();
3589 unsigned ShiftAmt2 = (unsigned)CUI->getValue();
3591 // Check for (A << c1) << c2 and (A >> c1) >> c2
3592 if (I.getOpcode() == Op0SI->getOpcode()) {
3593 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
3594 if (Op0->getType()->getPrimitiveSizeInBits() < Amt)
3595 Amt = Op0->getType()->getPrimitiveSizeInBits();
3596 return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
3597 ConstantUInt::get(Type::UByteTy, Amt));
3600 // Check for (A << c1) >> c2 or visaversa. If we are dealing with
3601 // signed types, we can only support the (A >> c1) << c2 configuration,
3602 // because it can not turn an arbitrary bit of A into a sign bit.
3603 if (I.getType()->isUnsigned() || isLeftShift) {
3604 // Calculate bitmask for what gets shifted off the edge...
3605 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
3607 C = ConstantExpr::getShl(C, ShiftAmt1C);
3609 C = ConstantExpr::getShr(C, ShiftAmt1C);
3612 BinaryOperator::createAnd(Op0SI->getOperand(0), C,
3613 Op0SI->getOperand(0)->getName()+".mask");
3614 InsertNewInstBefore(Mask, I);
3616 // Figure out what flavor of shift we should use...
3617 if (ShiftAmt1 == ShiftAmt2)
3618 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
3619 else if (ShiftAmt1 < ShiftAmt2) {
3620 return new ShiftInst(I.getOpcode(), Mask,
3621 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
3623 return new ShiftInst(Op0SI->getOpcode(), Mask,
3624 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
3627 // We can handle signed (X << C1) >> C2 if it's a sign extend. In
3628 // this case, C1 == C2 and C1 is 8, 16, or 32.
3629 if (ShiftAmt1 == ShiftAmt2) {
3630 const Type *SExtType = 0;
3631 switch (ShiftAmt1) {
3632 case 8 : SExtType = Type::SByteTy; break;
3633 case 16: SExtType = Type::ShortTy; break;
3634 case 32: SExtType = Type::IntTy; break;
3638 Instruction *NewTrunc = new CastInst(Op0SI->getOperand(0),
3640 InsertNewInstBefore(NewTrunc, I);
3641 return new CastInst(NewTrunc, I.getType());
3658 /// getCastType - In the future, we will split the cast instruction into these
3659 /// various types. Until then, we have to do the analysis here.
3660 static CastType getCastType(const Type *Src, const Type *Dest) {
3661 assert(Src->isIntegral() && Dest->isIntegral() &&
3662 "Only works on integral types!");
3663 unsigned SrcSize = Src->getPrimitiveSizeInBits();
3664 unsigned DestSize = Dest->getPrimitiveSizeInBits();
3666 if (SrcSize == DestSize) return Noop;
3667 if (SrcSize > DestSize) return Truncate;
3668 if (Src->isSigned()) return Signext;
3673 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
3676 static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
3677 const Type *DstTy, TargetData *TD) {
3679 // It is legal to eliminate the instruction if casting A->B->A if the sizes
3680 // are identical and the bits don't get reinterpreted (for example
3681 // int->float->int would not be allowed).
3682 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
3685 // If we are casting between pointer and integer types, treat pointers as
3686 // integers of the appropriate size for the code below.
3687 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
3688 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
3689 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
3691 // Allow free casting and conversion of sizes as long as the sign doesn't
3693 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
3694 CastType FirstCast = getCastType(SrcTy, MidTy);
3695 CastType SecondCast = getCastType(MidTy, DstTy);
3697 // Capture the effect of these two casts. If the result is a legal cast,
3698 // the CastType is stored here, otherwise a special code is used.
3699 static const unsigned CastResult[] = {
3700 // First cast is noop
3702 // First cast is a truncate
3703 1, 1, 4, 4, // trunc->extend is not safe to eliminate
3704 // First cast is a sign ext
3705 2, 5, 2, 4, // signext->zeroext never ok
3706 // First cast is a zero ext
3710 unsigned Result = CastResult[FirstCast*4+SecondCast];
3712 default: assert(0 && "Illegal table value!");
3717 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
3718 // truncates, we could eliminate more casts.
3719 return (unsigned)getCastType(SrcTy, DstTy) == Result;
3721 return false; // Not possible to eliminate this here.
3723 // Sign or zero extend followed by truncate is always ok if the result
3724 // is a truncate or noop.
3725 CastType ResultCast = getCastType(SrcTy, DstTy);
3726 if (ResultCast == Noop || ResultCast == Truncate)
3728 // Otherwise we are still growing the value, we are only safe if the
3729 // result will match the sign/zeroextendness of the result.
3730 return ResultCast == FirstCast;
3736 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
3737 if (V->getType() == Ty || isa<Constant>(V)) return false;
3738 if (const CastInst *CI = dyn_cast<CastInst>(V))
3739 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
3745 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
3746 /// InsertBefore instruction. This is specialized a bit to avoid inserting
3747 /// casts that are known to not do anything...
3749 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
3750 Instruction *InsertBefore) {
3751 if (V->getType() == DestTy) return V;
3752 if (Constant *C = dyn_cast<Constant>(V))
3753 return ConstantExpr::getCast(C, DestTy);
3755 CastInst *CI = new CastInst(V, DestTy, V->getName());
3756 InsertNewInstBefore(CI, *InsertBefore);
3760 // CastInst simplification
3762 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
3763 Value *Src = CI.getOperand(0);
3765 // If the user is casting a value to the same type, eliminate this cast
3767 if (CI.getType() == Src->getType())
3768 return ReplaceInstUsesWith(CI, Src);
3770 if (isa<UndefValue>(Src)) // cast undef -> undef
3771 return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
3773 // If casting the result of another cast instruction, try to eliminate this
3776 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
3777 Value *A = CSrc->getOperand(0);
3778 if (isEliminableCastOfCast(A->getType(), CSrc->getType(),
3779 CI.getType(), TD)) {
3780 // This instruction now refers directly to the cast's src operand. This
3781 // has a good chance of making CSrc dead.
3782 CI.setOperand(0, CSrc->getOperand(0));
3786 // If this is an A->B->A cast, and we are dealing with integral types, try
3787 // to convert this into a logical 'and' instruction.
3789 if (A->getType()->isInteger() &&
3790 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
3791 CSrc->getType()->isUnsigned() && // B->A cast must zero extend
3792 CSrc->getType()->getPrimitiveSizeInBits() <
3793 CI.getType()->getPrimitiveSizeInBits()&&
3794 A->getType()->getPrimitiveSizeInBits() ==
3795 CI.getType()->getPrimitiveSizeInBits()) {
3796 assert(CSrc->getType() != Type::ULongTy &&
3797 "Cannot have type bigger than ulong!");
3798 uint64_t AndValue = ~0ULL>>(64-CSrc->getType()->getPrimitiveSizeInBits());
3799 Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(),
3801 AndOp = ConstantExpr::getCast(AndOp, A->getType());
3802 Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
3803 if (And->getType() != CI.getType()) {
3804 And->setName(CSrc->getName()+".mask");
3805 InsertNewInstBefore(And, CI);
3806 And = new CastInst(And, CI.getType());
3812 // If this is a cast to bool, turn it into the appropriate setne instruction.
3813 if (CI.getType() == Type::BoolTy)
3814 return BinaryOperator::createSetNE(CI.getOperand(0),
3815 Constant::getNullValue(CI.getOperand(0)->getType()));
3817 // If casting the result of a getelementptr instruction with no offset, turn
3818 // this into a cast of the original pointer!
3820 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
3821 bool AllZeroOperands = true;
3822 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
3823 if (!isa<Constant>(GEP->getOperand(i)) ||
3824 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
3825 AllZeroOperands = false;
3828 if (AllZeroOperands) {
3829 CI.setOperand(0, GEP->getOperand(0));
3834 // If we are casting a malloc or alloca to a pointer to a type of the same
3835 // size, rewrite the allocation instruction to allocate the "right" type.
3837 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
3838 if (AI->hasOneUse() && !AI->isArrayAllocation())
3839 if (const PointerType *PTy = dyn_cast<PointerType>(CI.getType())) {
3840 // Get the type really allocated and the type casted to...
3841 const Type *AllocElTy = AI->getAllocatedType();
3842 const Type *CastElTy = PTy->getElementType();
3843 if (AllocElTy->isSized() && CastElTy->isSized()) {
3844 uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
3845 uint64_t CastElTySize = TD->getTypeSize(CastElTy);
3847 // If the allocation is for an even multiple of the cast type size
3848 if (CastElTySize && (AllocElTySize % CastElTySize == 0)) {
3849 Value *Amt = ConstantUInt::get(Type::UIntTy,
3850 AllocElTySize/CastElTySize);
3851 std::string Name = AI->getName(); AI->setName("");
3852 AllocationInst *New;
3853 if (isa<MallocInst>(AI))
3854 New = new MallocInst(CastElTy, Amt, Name);
3856 New = new AllocaInst(CastElTy, Amt, Name);
3857 InsertNewInstBefore(New, *AI);
3858 return ReplaceInstUsesWith(CI, New);
3863 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
3864 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
3866 if (isa<PHINode>(Src))
3867 if (Instruction *NV = FoldOpIntoPhi(CI))
3870 // If the source value is an instruction with only this use, we can attempt to
3871 // propagate the cast into the instruction. Also, only handle integral types
3873 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
3874 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
3875 CI.getType()->isInteger()) { // Don't mess with casts to bool here
3876 const Type *DestTy = CI.getType();
3877 unsigned SrcBitSize = Src->getType()->getPrimitiveSizeInBits();
3878 unsigned DestBitSize = DestTy->getPrimitiveSizeInBits();
3880 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
3881 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
3883 switch (SrcI->getOpcode()) {
3884 case Instruction::Add:
3885 case Instruction::Mul:
3886 case Instruction::And:
3887 case Instruction::Or:
3888 case Instruction::Xor:
3889 // If we are discarding information, or just changing the sign, rewrite.
3890 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
3891 // Don't insert two casts if they cannot be eliminated. We allow two
3892 // casts to be inserted if the sizes are the same. This could only be
3893 // converting signedness, which is a noop.
3894 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
3895 !ValueRequiresCast(Op0, DestTy, TD)) {
3896 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
3897 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
3898 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
3899 ->getOpcode(), Op0c, Op1c);
3903 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
3904 if (SrcBitSize == 1 && SrcI->getOpcode() == Instruction::Xor &&
3905 Op1 == ConstantBool::True &&
3906 (!Op0->hasOneUse() || !isa<SetCondInst>(Op0))) {
3907 Value *New = InsertOperandCastBefore(Op0, DestTy, &CI);
3908 return BinaryOperator::createXor(New,
3909 ConstantInt::get(CI.getType(), 1));
3912 case Instruction::Shl:
3913 // Allow changing the sign of the source operand. Do not allow changing
3914 // the size of the shift, UNLESS the shift amount is a constant. We
3915 // mush not change variable sized shifts to a smaller size, because it
3916 // is undefined to shift more bits out than exist in the value.
3917 if (DestBitSize == SrcBitSize ||
3918 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
3919 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
3920 return new ShiftInst(Instruction::Shl, Op0c, Op1);
3923 case Instruction::Shr:
3924 // If this is a signed shr, and if all bits shifted in are about to be
3925 // truncated off, turn it into an unsigned shr to allow greater
3927 if (DestBitSize < SrcBitSize && Src->getType()->isSigned() &&
3928 isa<ConstantInt>(Op1)) {
3929 unsigned ShiftAmt = cast<ConstantUInt>(Op1)->getValue();
3930 if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
3931 // Convert to unsigned.
3932 Value *N1 = InsertOperandCastBefore(Op0,
3933 Op0->getType()->getUnsignedVersion(), &CI);
3934 // Insert the new shift, which is now unsigned.
3935 N1 = InsertNewInstBefore(new ShiftInst(Instruction::Shr, N1,
3936 Op1, Src->getName()), CI);
3937 return new CastInst(N1, CI.getType());
3942 case Instruction::SetNE:
3943 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
3944 if (Op1C->getRawValue() == 0) {
3945 // If the input only has the low bit set, simplify directly.
3947 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
3948 // cast (X != 0) to int --> X if X&~1 == 0
3949 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
3950 if (CI.getType() == Op0->getType())
3951 return ReplaceInstUsesWith(CI, Op0);
3953 return new CastInst(Op0, CI.getType());
3956 // If the input is an and with a single bit, shift then simplify.
3957 ConstantInt *AndRHS;
3958 if (match(Op0, m_And(m_Value(), m_ConstantInt(AndRHS))))
3959 if (AndRHS->getRawValue() &&
3960 (AndRHS->getRawValue() & (AndRHS->getRawValue()-1)) == 0) {
3961 unsigned ShiftAmt = Log2_64(AndRHS->getRawValue());
3962 // Perform an unsigned shr by shiftamt. Convert input to
3963 // unsigned if it is signed.
3965 if (In->getType()->isSigned())
3966 In = InsertNewInstBefore(new CastInst(In,
3967 In->getType()->getUnsignedVersion(), In->getName()),CI);
3968 // Insert the shift to put the result in the low bit.
3969 In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In,
3970 ConstantInt::get(Type::UByteTy, ShiftAmt),
3971 In->getName()+".lobit"), CI);
3972 if (CI.getType() == In->getType())
3973 return ReplaceInstUsesWith(CI, In);
3975 return new CastInst(In, CI.getType());
3980 case Instruction::SetEQ:
3981 // We if we are just checking for a seteq of a single bit and casting it
3982 // to an integer. If so, shift the bit to the appropriate place then
3983 // cast to integer to avoid the comparison.
3984 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
3985 // Is Op1C a power of two or zero?
3986 if ((Op1C->getRawValue() & Op1C->getRawValue()-1) == 0) {
3987 // cast (X == 1) to int -> X iff X has only the low bit set.
3988 if (Op1C->getRawValue() == 1) {
3990 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
3991 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
3992 if (CI.getType() == Op0->getType())
3993 return ReplaceInstUsesWith(CI, Op0);
3995 return new CastInst(Op0, CI.getType());
4006 /// GetSelectFoldableOperands - We want to turn code that looks like this:
4008 /// %D = select %cond, %C, %A
4010 /// %C = select %cond, %B, 0
4013 /// Assuming that the specified instruction is an operand to the select, return
4014 /// a bitmask indicating which operands of this instruction are foldable if they
4015 /// equal the other incoming value of the select.
4017 static unsigned GetSelectFoldableOperands(Instruction *I) {
4018 switch (I->getOpcode()) {
4019 case Instruction::Add:
4020 case Instruction::Mul:
4021 case Instruction::And:
4022 case Instruction::Or:
4023 case Instruction::Xor:
4024 return 3; // Can fold through either operand.
4025 case Instruction::Sub: // Can only fold on the amount subtracted.
4026 case Instruction::Shl: // Can only fold on the shift amount.
4027 case Instruction::Shr:
4030 return 0; // Cannot fold
4034 /// GetSelectFoldableConstant - For the same transformation as the previous
4035 /// function, return the identity constant that goes into the select.
4036 static Constant *GetSelectFoldableConstant(Instruction *I) {
4037 switch (I->getOpcode()) {
4038 default: assert(0 && "This cannot happen!"); abort();
4039 case Instruction::Add:
4040 case Instruction::Sub:
4041 case Instruction::Or:
4042 case Instruction::Xor:
4043 return Constant::getNullValue(I->getType());
4044 case Instruction::Shl:
4045 case Instruction::Shr:
4046 return Constant::getNullValue(Type::UByteTy);
4047 case Instruction::And:
4048 return ConstantInt::getAllOnesValue(I->getType());
4049 case Instruction::Mul:
4050 return ConstantInt::get(I->getType(), 1);
4054 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
4055 /// have the same opcode and only one use each. Try to simplify this.
4056 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
4058 if (TI->getNumOperands() == 1) {
4059 // If this is a non-volatile load or a cast from the same type,
4061 if (TI->getOpcode() == Instruction::Cast) {
4062 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
4065 return 0; // unknown unary op.
4068 // Fold this by inserting a select from the input values.
4069 SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
4070 FI->getOperand(0), SI.getName()+".v");
4071 InsertNewInstBefore(NewSI, SI);
4072 return new CastInst(NewSI, TI->getType());
4075 // Only handle binary operators here.
4076 if (!isa<ShiftInst>(TI) && !isa<BinaryOperator>(TI))
4079 // Figure out if the operations have any operands in common.
4080 Value *MatchOp, *OtherOpT, *OtherOpF;
4082 if (TI->getOperand(0) == FI->getOperand(0)) {
4083 MatchOp = TI->getOperand(0);
4084 OtherOpT = TI->getOperand(1);
4085 OtherOpF = FI->getOperand(1);
4086 MatchIsOpZero = true;
4087 } else if (TI->getOperand(1) == FI->getOperand(1)) {
4088 MatchOp = TI->getOperand(1);
4089 OtherOpT = TI->getOperand(0);
4090 OtherOpF = FI->getOperand(0);
4091 MatchIsOpZero = false;
4092 } else if (!TI->isCommutative()) {
4094 } else if (TI->getOperand(0) == FI->getOperand(1)) {
4095 MatchOp = TI->getOperand(0);
4096 OtherOpT = TI->getOperand(1);
4097 OtherOpF = FI->getOperand(0);
4098 MatchIsOpZero = true;
4099 } else if (TI->getOperand(1) == FI->getOperand(0)) {
4100 MatchOp = TI->getOperand(1);
4101 OtherOpT = TI->getOperand(0);
4102 OtherOpF = FI->getOperand(1);
4103 MatchIsOpZero = true;
4108 // If we reach here, they do have operations in common.
4109 SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
4110 OtherOpF, SI.getName()+".v");
4111 InsertNewInstBefore(NewSI, SI);
4113 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
4115 return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
4117 return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
4120 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI);
4122 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp);
4126 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
4127 Value *CondVal = SI.getCondition();
4128 Value *TrueVal = SI.getTrueValue();
4129 Value *FalseVal = SI.getFalseValue();
4131 // select true, X, Y -> X
4132 // select false, X, Y -> Y
4133 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
4134 if (C == ConstantBool::True)
4135 return ReplaceInstUsesWith(SI, TrueVal);
4137 assert(C == ConstantBool::False);
4138 return ReplaceInstUsesWith(SI, FalseVal);
4141 // select C, X, X -> X
4142 if (TrueVal == FalseVal)
4143 return ReplaceInstUsesWith(SI, TrueVal);
4145 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
4146 return ReplaceInstUsesWith(SI, FalseVal);
4147 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
4148 return ReplaceInstUsesWith(SI, TrueVal);
4149 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
4150 if (isa<Constant>(TrueVal))
4151 return ReplaceInstUsesWith(SI, TrueVal);
4153 return ReplaceInstUsesWith(SI, FalseVal);
4156 if (SI.getType() == Type::BoolTy)
4157 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
4158 if (C == ConstantBool::True) {
4159 // Change: A = select B, true, C --> A = or B, C
4160 return BinaryOperator::createOr(CondVal, FalseVal);
4162 // Change: A = select B, false, C --> A = and !B, C
4164 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4165 "not."+CondVal->getName()), SI);
4166 return BinaryOperator::createAnd(NotCond, FalseVal);
4168 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
4169 if (C == ConstantBool::False) {
4170 // Change: A = select B, C, false --> A = and B, C
4171 return BinaryOperator::createAnd(CondVal, TrueVal);
4173 // Change: A = select B, C, true --> A = or !B, C
4175 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4176 "not."+CondVal->getName()), SI);
4177 return BinaryOperator::createOr(NotCond, TrueVal);
4181 // Selecting between two integer constants?
4182 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
4183 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
4184 // select C, 1, 0 -> cast C to int
4185 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
4186 return new CastInst(CondVal, SI.getType());
4187 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
4188 // select C, 0, 1 -> cast !C to int
4190 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4191 "not."+CondVal->getName()), SI);
4192 return new CastInst(NotCond, SI.getType());
4195 // If one of the constants is zero (we know they can't both be) and we
4196 // have a setcc instruction with zero, and we have an 'and' with the
4197 // non-constant value, eliminate this whole mess. This corresponds to
4198 // cases like this: ((X & 27) ? 27 : 0)
4199 if (TrueValC->isNullValue() || FalseValC->isNullValue())
4200 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
4201 if ((IC->getOpcode() == Instruction::SetEQ ||
4202 IC->getOpcode() == Instruction::SetNE) &&
4203 isa<ConstantInt>(IC->getOperand(1)) &&
4204 cast<Constant>(IC->getOperand(1))->isNullValue())
4205 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
4206 if (ICA->getOpcode() == Instruction::And &&
4207 isa<ConstantInt>(ICA->getOperand(1)) &&
4208 (ICA->getOperand(1) == TrueValC ||
4209 ICA->getOperand(1) == FalseValC) &&
4210 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
4211 // Okay, now we know that everything is set up, we just don't
4212 // know whether we have a setne or seteq and whether the true or
4213 // false val is the zero.
4214 bool ShouldNotVal = !TrueValC->isNullValue();
4215 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
4218 V = InsertNewInstBefore(BinaryOperator::create(
4219 Instruction::Xor, V, ICA->getOperand(1)), SI);
4220 return ReplaceInstUsesWith(SI, V);
4224 // See if we are selecting two values based on a comparison of the two values.
4225 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
4226 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
4227 // Transform (X == Y) ? X : Y -> Y
4228 if (SCI->getOpcode() == Instruction::SetEQ)
4229 return ReplaceInstUsesWith(SI, FalseVal);
4230 // Transform (X != Y) ? X : Y -> X
4231 if (SCI->getOpcode() == Instruction::SetNE)
4232 return ReplaceInstUsesWith(SI, TrueVal);
4233 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
4235 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
4236 // Transform (X == Y) ? Y : X -> X
4237 if (SCI->getOpcode() == Instruction::SetEQ)
4238 return ReplaceInstUsesWith(SI, FalseVal);
4239 // Transform (X != Y) ? Y : X -> Y
4240 if (SCI->getOpcode() == Instruction::SetNE)
4241 return ReplaceInstUsesWith(SI, TrueVal);
4242 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
4246 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
4247 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
4248 if (TI->hasOneUse() && FI->hasOneUse()) {
4249 bool isInverse = false;
4250 Instruction *AddOp = 0, *SubOp = 0;
4252 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
4253 if (TI->getOpcode() == FI->getOpcode())
4254 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
4257 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
4258 // even legal for FP.
4259 if (TI->getOpcode() == Instruction::Sub &&
4260 FI->getOpcode() == Instruction::Add) {
4261 AddOp = FI; SubOp = TI;
4262 } else if (FI->getOpcode() == Instruction::Sub &&
4263 TI->getOpcode() == Instruction::Add) {
4264 AddOp = TI; SubOp = FI;
4268 Value *OtherAddOp = 0;
4269 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
4270 OtherAddOp = AddOp->getOperand(1);
4271 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
4272 OtherAddOp = AddOp->getOperand(0);
4276 // So at this point we know we have:
4277 // select C, (add X, Y), (sub X, ?)
4278 // We can do the transform profitably if either 'Y' = '?' or '?' is
4280 if (SubOp->getOperand(1) == AddOp ||
4281 isa<Constant>(SubOp->getOperand(1))) {
4283 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
4284 NegVal = ConstantExpr::getNeg(C);
4286 NegVal = InsertNewInstBefore(
4287 BinaryOperator::createNeg(SubOp->getOperand(1)), SI);
4290 Value *NewTrueOp = OtherAddOp;
4291 Value *NewFalseOp = NegVal;
4293 std::swap(NewTrueOp, NewFalseOp);
4294 Instruction *NewSel =
4295 new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
4297 NewSel = InsertNewInstBefore(NewSel, SI);
4298 return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
4304 // See if we can fold the select into one of our operands.
4305 if (SI.getType()->isInteger()) {
4306 // See the comment above GetSelectFoldableOperands for a description of the
4307 // transformation we are doing here.
4308 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
4309 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
4310 !isa<Constant>(FalseVal))
4311 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
4312 unsigned OpToFold = 0;
4313 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
4315 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
4320 Constant *C = GetSelectFoldableConstant(TVI);
4321 std::string Name = TVI->getName(); TVI->setName("");
4322 Instruction *NewSel =
4323 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
4325 InsertNewInstBefore(NewSel, SI);
4326 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
4327 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
4328 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
4329 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
4331 assert(0 && "Unknown instruction!!");
4336 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
4337 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
4338 !isa<Constant>(TrueVal))
4339 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
4340 unsigned OpToFold = 0;
4341 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
4343 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
4348 Constant *C = GetSelectFoldableConstant(FVI);
4349 std::string Name = FVI->getName(); FVI->setName("");
4350 Instruction *NewSel =
4351 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
4353 InsertNewInstBefore(NewSel, SI);
4354 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
4355 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
4356 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
4357 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
4359 assert(0 && "Unknown instruction!!");
4365 if (BinaryOperator::isNot(CondVal)) {
4366 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
4367 SI.setOperand(1, FalseVal);
4368 SI.setOperand(2, TrueVal);
4376 // CallInst simplification
4378 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
4379 // Intrinsics cannot occur in an invoke, so handle them here instead of in
4381 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(&CI)) {
4382 bool Changed = false;
4384 // memmove/cpy/set of zero bytes is a noop.
4385 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
4386 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
4388 // FIXME: Increase alignment here.
4390 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
4391 if (CI->getRawValue() == 1) {
4392 // Replace the instruction with just byte operations. We would
4393 // transform other cases to loads/stores, but we don't know if
4394 // alignment is sufficient.
4398 // If we have a memmove and the source operation is a constant global,
4399 // then the source and dest pointers can't alias, so we can change this
4400 // into a call to memcpy.
4401 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI))
4402 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
4403 if (GVSrc->isConstant()) {
4404 Module *M = CI.getParent()->getParent()->getParent();
4405 Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
4406 CI.getCalledFunction()->getFunctionType());
4407 CI.setOperand(0, MemCpy);
4411 if (Changed) return &CI;
4412 } else if (DbgStopPointInst *SPI = dyn_cast<DbgStopPointInst>(&CI)) {
4413 // If this stoppoint is at the same source location as the previous
4414 // stoppoint in the chain, it is not needed.
4415 if (DbgStopPointInst *PrevSPI =
4416 dyn_cast<DbgStopPointInst>(SPI->getChain()))
4417 if (SPI->getLineNo() == PrevSPI->getLineNo() &&
4418 SPI->getColNo() == PrevSPI->getColNo()) {
4419 SPI->replaceAllUsesWith(PrevSPI);
4420 return EraseInstFromFunction(CI);
4424 return visitCallSite(&CI);
4427 // InvokeInst simplification
4429 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
4430 return visitCallSite(&II);
4433 // visitCallSite - Improvements for call and invoke instructions.
4435 Instruction *InstCombiner::visitCallSite(CallSite CS) {
4436 bool Changed = false;
4438 // If the callee is a constexpr cast of a function, attempt to move the cast
4439 // to the arguments of the call/invoke.
4440 if (transformConstExprCastCall(CS)) return 0;
4442 Value *Callee = CS.getCalledValue();
4444 if (Function *CalleeF = dyn_cast<Function>(Callee))
4445 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
4446 Instruction *OldCall = CS.getInstruction();
4447 // If the call and callee calling conventions don't match, this call must
4448 // be unreachable, as the call is undefined.
4449 new StoreInst(ConstantBool::True,
4450 UndefValue::get(PointerType::get(Type::BoolTy)), OldCall);
4451 if (!OldCall->use_empty())
4452 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
4453 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
4454 return EraseInstFromFunction(*OldCall);
4458 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
4459 // This instruction is not reachable, just remove it. We insert a store to
4460 // undef so that we know that this code is not reachable, despite the fact
4461 // that we can't modify the CFG here.
4462 new StoreInst(ConstantBool::True,
4463 UndefValue::get(PointerType::get(Type::BoolTy)),
4464 CS.getInstruction());
4466 if (!CS.getInstruction()->use_empty())
4467 CS.getInstruction()->
4468 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
4470 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
4471 // Don't break the CFG, insert a dummy cond branch.
4472 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
4473 ConstantBool::True, II);
4475 return EraseInstFromFunction(*CS.getInstruction());
4478 const PointerType *PTy = cast<PointerType>(Callee->getType());
4479 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
4480 if (FTy->isVarArg()) {
4481 // See if we can optimize any arguments passed through the varargs area of
4483 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
4484 E = CS.arg_end(); I != E; ++I)
4485 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
4486 // If this cast does not effect the value passed through the varargs
4487 // area, we can eliminate the use of the cast.
4488 Value *Op = CI->getOperand(0);
4489 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
4496 return Changed ? CS.getInstruction() : 0;
4499 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
4500 // attempt to move the cast to the arguments of the call/invoke.
4502 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
4503 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
4504 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
4505 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
4507 Function *Callee = cast<Function>(CE->getOperand(0));
4508 Instruction *Caller = CS.getInstruction();
4510 // Okay, this is a cast from a function to a different type. Unless doing so
4511 // would cause a type conversion of one of our arguments, change this call to
4512 // be a direct call with arguments casted to the appropriate types.
4514 const FunctionType *FT = Callee->getFunctionType();
4515 const Type *OldRetTy = Caller->getType();
4517 // Check to see if we are changing the return type...
4518 if (OldRetTy != FT->getReturnType()) {
4519 if (Callee->isExternal() &&
4520 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
4521 !Caller->use_empty())
4522 return false; // Cannot transform this return value...
4524 // If the callsite is an invoke instruction, and the return value is used by
4525 // a PHI node in a successor, we cannot change the return type of the call
4526 // because there is no place to put the cast instruction (without breaking
4527 // the critical edge). Bail out in this case.
4528 if (!Caller->use_empty())
4529 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
4530 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
4532 if (PHINode *PN = dyn_cast<PHINode>(*UI))
4533 if (PN->getParent() == II->getNormalDest() ||
4534 PN->getParent() == II->getUnwindDest())
4538 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
4539 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
4541 CallSite::arg_iterator AI = CS.arg_begin();
4542 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
4543 const Type *ParamTy = FT->getParamType(i);
4544 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
4545 if (Callee->isExternal() && !isConvertible) return false;
4548 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
4549 Callee->isExternal())
4550 return false; // Do not delete arguments unless we have a function body...
4552 // Okay, we decided that this is a safe thing to do: go ahead and start
4553 // inserting cast instructions as necessary...
4554 std::vector<Value*> Args;
4555 Args.reserve(NumActualArgs);
4557 AI = CS.arg_begin();
4558 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
4559 const Type *ParamTy = FT->getParamType(i);
4560 if ((*AI)->getType() == ParamTy) {
4561 Args.push_back(*AI);
4563 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
4568 // If the function takes more arguments than the call was taking, add them
4570 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
4571 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
4573 // If we are removing arguments to the function, emit an obnoxious warning...
4574 if (FT->getNumParams() < NumActualArgs)
4575 if (!FT->isVarArg()) {
4576 std::cerr << "WARNING: While resolving call to function '"
4577 << Callee->getName() << "' arguments were dropped!\n";
4579 // Add all of the arguments in their promoted form to the arg list...
4580 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
4581 const Type *PTy = getPromotedType((*AI)->getType());
4582 if (PTy != (*AI)->getType()) {
4583 // Must promote to pass through va_arg area!
4584 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
4585 InsertNewInstBefore(Cast, *Caller);
4586 Args.push_back(Cast);
4588 Args.push_back(*AI);
4593 if (FT->getReturnType() == Type::VoidTy)
4594 Caller->setName(""); // Void type should not have a name...
4597 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4598 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
4599 Args, Caller->getName(), Caller);
4600 cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
4602 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
4603 if (cast<CallInst>(Caller)->isTailCall())
4604 cast<CallInst>(NC)->setTailCall();
4605 cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
4608 // Insert a cast of the return type as necessary...
4610 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
4611 if (NV->getType() != Type::VoidTy) {
4612 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
4614 // If this is an invoke instruction, we should insert it after the first
4615 // non-phi, instruction in the normal successor block.
4616 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4617 BasicBlock::iterator I = II->getNormalDest()->begin();
4618 while (isa<PHINode>(I)) ++I;
4619 InsertNewInstBefore(NC, *I);
4621 // Otherwise, it's a call, just insert cast right after the call instr
4622 InsertNewInstBefore(NC, *Caller);
4624 AddUsersToWorkList(*Caller);
4626 NV = UndefValue::get(Caller->getType());
4630 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
4631 Caller->replaceAllUsesWith(NV);
4632 Caller->getParent()->getInstList().erase(Caller);
4633 removeFromWorkList(Caller);
4638 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
4639 // operator and they all are only used by the PHI, PHI together their
4640 // inputs, and do the operation once, to the result of the PHI.
4641 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
4642 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
4644 // Scan the instruction, looking for input operations that can be folded away.
4645 // If all input operands to the phi are the same instruction (e.g. a cast from
4646 // the same type or "+42") we can pull the operation through the PHI, reducing
4647 // code size and simplifying code.
4648 Constant *ConstantOp = 0;
4649 const Type *CastSrcTy = 0;
4650 if (isa<CastInst>(FirstInst)) {
4651 CastSrcTy = FirstInst->getOperand(0)->getType();
4652 } else if (isa<BinaryOperator>(FirstInst) || isa<ShiftInst>(FirstInst)) {
4653 // Can fold binop or shift if the RHS is a constant.
4654 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
4655 if (ConstantOp == 0) return 0;
4657 return 0; // Cannot fold this operation.
4660 // Check to see if all arguments are the same operation.
4661 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4662 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
4663 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
4664 if (!I->hasOneUse() || I->getOpcode() != FirstInst->getOpcode())
4667 if (I->getOperand(0)->getType() != CastSrcTy)
4668 return 0; // Cast operation must match.
4669 } else if (I->getOperand(1) != ConstantOp) {
4674 // Okay, they are all the same operation. Create a new PHI node of the
4675 // correct type, and PHI together all of the LHS's of the instructions.
4676 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
4677 PN.getName()+".in");
4678 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
4680 Value *InVal = FirstInst->getOperand(0);
4681 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
4683 // Add all operands to the new PHI.
4684 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4685 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
4686 if (NewInVal != InVal)
4688 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
4693 // The new PHI unions all of the same values together. This is really
4694 // common, so we handle it intelligently here for compile-time speed.
4698 InsertNewInstBefore(NewPN, PN);
4702 // Insert and return the new operation.
4703 if (isa<CastInst>(FirstInst))
4704 return new CastInst(PhiVal, PN.getType());
4705 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
4706 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
4708 return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(),
4709 PhiVal, ConstantOp);
4712 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
4714 static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &PotentiallyDeadPHIs) {
4715 if (PN->use_empty()) return true;
4716 if (!PN->hasOneUse()) return false;
4718 // Remember this node, and if we find the cycle, return.
4719 if (!PotentiallyDeadPHIs.insert(PN).second)
4722 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
4723 return DeadPHICycle(PU, PotentiallyDeadPHIs);
4728 // PHINode simplification
4730 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
4731 if (Value *V = PN.hasConstantValue())
4732 return ReplaceInstUsesWith(PN, V);
4734 // If the only user of this instruction is a cast instruction, and all of the
4735 // incoming values are constants, change this PHI to merge together the casted
4738 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
4739 if (CI->getType() != PN.getType()) { // noop casts will be folded
4740 bool AllConstant = true;
4741 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
4742 if (!isa<Constant>(PN.getIncomingValue(i))) {
4743 AllConstant = false;
4747 // Make a new PHI with all casted values.
4748 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
4749 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
4750 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
4751 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
4752 PN.getIncomingBlock(i));
4755 // Update the cast instruction.
4756 CI->setOperand(0, New);
4757 WorkList.push_back(CI); // revisit the cast instruction to fold.
4758 WorkList.push_back(New); // Make sure to revisit the new Phi
4759 return &PN; // PN is now dead!
4763 // If all PHI operands are the same operation, pull them through the PHI,
4764 // reducing code size.
4765 if (isa<Instruction>(PN.getIncomingValue(0)) &&
4766 PN.getIncomingValue(0)->hasOneUse())
4767 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
4770 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
4771 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
4772 // PHI)... break the cycle.
4774 if (PHINode *PU = dyn_cast<PHINode>(PN.use_back())) {
4775 std::set<PHINode*> PotentiallyDeadPHIs;
4776 PotentiallyDeadPHIs.insert(&PN);
4777 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
4778 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
4784 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
4785 Instruction *InsertPoint,
4787 unsigned PS = IC->getTargetData().getPointerSize();
4788 const Type *VTy = V->getType();
4789 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
4790 // We must insert a cast to ensure we sign-extend.
4791 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
4792 V->getName()), *InsertPoint);
4793 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
4798 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
4799 Value *PtrOp = GEP.getOperand(0);
4800 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
4801 // If so, eliminate the noop.
4802 if (GEP.getNumOperands() == 1)
4803 return ReplaceInstUsesWith(GEP, PtrOp);
4805 if (isa<UndefValue>(GEP.getOperand(0)))
4806 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
4808 bool HasZeroPointerIndex = false;
4809 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
4810 HasZeroPointerIndex = C->isNullValue();
4812 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
4813 return ReplaceInstUsesWith(GEP, PtrOp);
4815 // Eliminate unneeded casts for indices.
4816 bool MadeChange = false;
4817 gep_type_iterator GTI = gep_type_begin(GEP);
4818 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
4819 if (isa<SequentialType>(*GTI)) {
4820 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
4821 Value *Src = CI->getOperand(0);
4822 const Type *SrcTy = Src->getType();
4823 const Type *DestTy = CI->getType();
4824 if (Src->getType()->isInteger()) {
4825 if (SrcTy->getPrimitiveSizeInBits() ==
4826 DestTy->getPrimitiveSizeInBits()) {
4827 // We can always eliminate a cast from ulong or long to the other.
4828 // We can always eliminate a cast from uint to int or the other on
4829 // 32-bit pointer platforms.
4830 if (DestTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()){
4832 GEP.setOperand(i, Src);
4834 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
4835 SrcTy->getPrimitiveSize() == 4) {
4836 // We can always eliminate a cast from int to [u]long. We can
4837 // eliminate a cast from uint to [u]long iff the target is a 32-bit
4839 if (SrcTy->isSigned() ||
4840 SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
4842 GEP.setOperand(i, Src);
4847 // If we are using a wider index than needed for this platform, shrink it
4848 // to what we need. If the incoming value needs a cast instruction,
4849 // insert it. This explicit cast can make subsequent optimizations more
4851 Value *Op = GEP.getOperand(i);
4852 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
4853 if (Constant *C = dyn_cast<Constant>(Op)) {
4854 GEP.setOperand(i, ConstantExpr::getCast(C,
4855 TD->getIntPtrType()->getSignedVersion()));
4858 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
4859 Op->getName()), GEP);
4860 GEP.setOperand(i, Op);
4864 // If this is a constant idx, make sure to canonicalize it to be a signed
4865 // operand, otherwise CSE and other optimizations are pessimized.
4866 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
4867 GEP.setOperand(i, ConstantExpr::getCast(CUI,
4868 CUI->getType()->getSignedVersion()));
4872 if (MadeChange) return &GEP;
4874 // Combine Indices - If the source pointer to this getelementptr instruction
4875 // is a getelementptr instruction, combine the indices of the two
4876 // getelementptr instructions into a single instruction.
4878 std::vector<Value*> SrcGEPOperands;
4879 if (User *Src = dyn_castGetElementPtr(PtrOp))
4880 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
4882 if (!SrcGEPOperands.empty()) {
4883 // Note that if our source is a gep chain itself that we wait for that
4884 // chain to be resolved before we perform this transformation. This
4885 // avoids us creating a TON of code in some cases.
4887 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
4888 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
4889 return 0; // Wait until our source is folded to completion.
4891 std::vector<Value *> Indices;
4893 // Find out whether the last index in the source GEP is a sequential idx.
4894 bool EndsWithSequential = false;
4895 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
4896 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
4897 EndsWithSequential = !isa<StructType>(*I);
4899 // Can we combine the two pointer arithmetics offsets?
4900 if (EndsWithSequential) {
4901 // Replace: gep (gep %P, long B), long A, ...
4902 // With: T = long A+B; gep %P, T, ...
4904 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
4905 if (SO1 == Constant::getNullValue(SO1->getType())) {
4907 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
4910 // If they aren't the same type, convert both to an integer of the
4911 // target's pointer size.
4912 if (SO1->getType() != GO1->getType()) {
4913 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
4914 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
4915 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
4916 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
4918 unsigned PS = TD->getPointerSize();
4919 if (SO1->getType()->getPrimitiveSize() == PS) {
4920 // Convert GO1 to SO1's type.
4921 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
4923 } else if (GO1->getType()->getPrimitiveSize() == PS) {
4924 // Convert SO1 to GO1's type.
4925 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
4927 const Type *PT = TD->getIntPtrType();
4928 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
4929 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
4933 if (isa<Constant>(SO1) && isa<Constant>(GO1))
4934 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
4936 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
4937 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
4941 // Recycle the GEP we already have if possible.
4942 if (SrcGEPOperands.size() == 2) {
4943 GEP.setOperand(0, SrcGEPOperands[0]);
4944 GEP.setOperand(1, Sum);
4947 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
4948 SrcGEPOperands.end()-1);
4949 Indices.push_back(Sum);
4950 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
4952 } else if (isa<Constant>(*GEP.idx_begin()) &&
4953 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
4954 SrcGEPOperands.size() != 1) {
4955 // Otherwise we can do the fold if the first index of the GEP is a zero
4956 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
4957 SrcGEPOperands.end());
4958 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
4961 if (!Indices.empty())
4962 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
4964 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
4965 // GEP of global variable. If all of the indices for this GEP are
4966 // constants, we can promote this to a constexpr instead of an instruction.
4968 // Scan for nonconstants...
4969 std::vector<Constant*> Indices;
4970 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
4971 for (; I != E && isa<Constant>(*I); ++I)
4972 Indices.push_back(cast<Constant>(*I));
4974 if (I == E) { // If they are all constants...
4975 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
4977 // Replace all uses of the GEP with the new constexpr...
4978 return ReplaceInstUsesWith(GEP, CE);
4980 } else if (Value *X = isCast(PtrOp)) { // Is the operand a cast?
4981 if (!isa<PointerType>(X->getType())) {
4982 // Not interesting. Source pointer must be a cast from pointer.
4983 } else if (HasZeroPointerIndex) {
4984 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
4985 // into : GEP [10 x ubyte]* X, long 0, ...
4987 // This occurs when the program declares an array extern like "int X[];"
4989 const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
4990 const PointerType *XTy = cast<PointerType>(X->getType());
4991 if (const ArrayType *XATy =
4992 dyn_cast<ArrayType>(XTy->getElementType()))
4993 if (const ArrayType *CATy =
4994 dyn_cast<ArrayType>(CPTy->getElementType()))
4995 if (CATy->getElementType() == XATy->getElementType()) {
4996 // At this point, we know that the cast source type is a pointer
4997 // to an array of the same type as the destination pointer
4998 // array. Because the array type is never stepped over (there
4999 // is a leading zero) we can fold the cast into this GEP.
5000 GEP.setOperand(0, X);
5003 } else if (GEP.getNumOperands() == 2) {
5004 // Transform things like:
5005 // %t = getelementptr ubyte* cast ([2 x int]* %str to uint*), uint %V
5006 // into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast
5007 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
5008 const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
5009 if (isa<ArrayType>(SrcElTy) &&
5010 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
5011 TD->getTypeSize(ResElTy)) {
5012 Value *V = InsertNewInstBefore(
5013 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
5014 GEP.getOperand(1), GEP.getName()), GEP);
5015 return new CastInst(V, GEP.getType());
5018 // Transform things like:
5019 // getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp
5020 // (where tmp = 8*tmp2) into:
5021 // getelementptr [100 x double]* %arr, int 0, int %tmp.2
5023 if (isa<ArrayType>(SrcElTy) &&
5024 (ResElTy == Type::SByteTy || ResElTy == Type::UByteTy)) {
5025 uint64_t ArrayEltSize =
5026 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType());
5028 // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
5029 // allow either a mul, shift, or constant here.
5031 ConstantInt *Scale = 0;
5032 if (ArrayEltSize == 1) {
5033 NewIdx = GEP.getOperand(1);
5034 Scale = ConstantInt::get(NewIdx->getType(), 1);
5035 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
5036 NewIdx = ConstantInt::get(CI->getType(), 1);
5038 } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
5039 if (Inst->getOpcode() == Instruction::Shl &&
5040 isa<ConstantInt>(Inst->getOperand(1))) {
5041 unsigned ShAmt =cast<ConstantUInt>(Inst->getOperand(1))->getValue();
5042 if (Inst->getType()->isSigned())
5043 Scale = ConstantSInt::get(Inst->getType(), 1ULL << ShAmt);
5045 Scale = ConstantUInt::get(Inst->getType(), 1ULL << ShAmt);
5046 NewIdx = Inst->getOperand(0);
5047 } else if (Inst->getOpcode() == Instruction::Mul &&
5048 isa<ConstantInt>(Inst->getOperand(1))) {
5049 Scale = cast<ConstantInt>(Inst->getOperand(1));
5050 NewIdx = Inst->getOperand(0);
5054 // If the index will be to exactly the right offset with the scale taken
5055 // out, perform the transformation.
5056 if (Scale && Scale->getRawValue() % ArrayEltSize == 0) {
5057 if (ConstantSInt *C = dyn_cast<ConstantSInt>(Scale))
5058 Scale = ConstantSInt::get(C->getType(),
5059 (int64_t)C->getRawValue() /
5060 (int64_t)ArrayEltSize);
5062 Scale = ConstantUInt::get(Scale->getType(),
5063 Scale->getRawValue() / ArrayEltSize);
5064 if (Scale->getRawValue() != 1) {
5065 Constant *C = ConstantExpr::getCast(Scale, NewIdx->getType());
5066 Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale");
5067 NewIdx = InsertNewInstBefore(Sc, GEP);
5070 // Insert the new GEP instruction.
5072 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
5073 NewIdx, GEP.getName());
5074 Idx = InsertNewInstBefore(Idx, GEP);
5075 return new CastInst(Idx, GEP.getType());
5084 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
5085 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
5086 if (AI.isArrayAllocation()) // Check C != 1
5087 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
5088 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
5089 AllocationInst *New = 0;
5091 // Create and insert the replacement instruction...
5092 if (isa<MallocInst>(AI))
5093 New = new MallocInst(NewTy, 0, AI.getName());
5095 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
5096 New = new AllocaInst(NewTy, 0, AI.getName());
5099 InsertNewInstBefore(New, AI);
5101 // Scan to the end of the allocation instructions, to skip over a block of
5102 // allocas if possible...
5104 BasicBlock::iterator It = New;
5105 while (isa<AllocationInst>(*It)) ++It;
5107 // Now that I is pointing to the first non-allocation-inst in the block,
5108 // insert our getelementptr instruction...
5110 Value *NullIdx = Constant::getNullValue(Type::IntTy);
5111 Value *V = new GetElementPtrInst(New, NullIdx, NullIdx,
5112 New->getName()+".sub", It);
5114 // Now make everything use the getelementptr instead of the original
5116 return ReplaceInstUsesWith(AI, V);
5117 } else if (isa<UndefValue>(AI.getArraySize())) {
5118 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5121 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
5122 // Note that we only do this for alloca's, because malloc should allocate and
5123 // return a unique pointer, even for a zero byte allocation.
5124 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
5125 TD->getTypeSize(AI.getAllocatedType()) == 0)
5126 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5131 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
5132 Value *Op = FI.getOperand(0);
5134 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
5135 if (CastInst *CI = dyn_cast<CastInst>(Op))
5136 if (isa<PointerType>(CI->getOperand(0)->getType())) {
5137 FI.setOperand(0, CI->getOperand(0));
5141 // free undef -> unreachable.
5142 if (isa<UndefValue>(Op)) {
5143 // Insert a new store to null because we cannot modify the CFG here.
5144 new StoreInst(ConstantBool::True,
5145 UndefValue::get(PointerType::get(Type::BoolTy)), &FI);
5146 return EraseInstFromFunction(FI);
5149 // If we have 'free null' delete the instruction. This can happen in stl code
5150 // when lots of inlining happens.
5151 if (isa<ConstantPointerNull>(Op))
5152 return EraseInstFromFunction(FI);
5158 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
5159 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
5160 User *CI = cast<User>(LI.getOperand(0));
5161 Value *CastOp = CI->getOperand(0);
5163 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5164 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5165 const Type *SrcPTy = SrcTy->getElementType();
5167 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5168 // If the source is an array, the code below will not succeed. Check to
5169 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5171 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5172 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5173 if (ASrcTy->getNumElements() != 0) {
5174 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5175 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5176 SrcTy = cast<PointerType>(CastOp->getType());
5177 SrcPTy = SrcTy->getElementType();
5180 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5181 // Do not allow turning this into a load of an integer, which is then
5182 // casted to a pointer, this pessimizes pointer analysis a lot.
5183 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
5184 IC.getTargetData().getTypeSize(SrcPTy) ==
5185 IC.getTargetData().getTypeSize(DestPTy)) {
5187 // Okay, we are casting from one integer or pointer type to another of
5188 // the same size. Instead of casting the pointer before the load, cast
5189 // the result of the loaded value.
5190 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
5192 LI.isVolatile()),LI);
5193 // Now cast the result of the load.
5194 return new CastInst(NewLoad, LI.getType());
5201 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
5202 /// from this value cannot trap. If it is not obviously safe to load from the
5203 /// specified pointer, we do a quick local scan of the basic block containing
5204 /// ScanFrom, to determine if the address is already accessed.
5205 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
5206 // If it is an alloca or global variable, it is always safe to load from.
5207 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
5209 // Otherwise, be a little bit agressive by scanning the local block where we
5210 // want to check to see if the pointer is already being loaded or stored
5211 // from/to. If so, the previous load or store would have already trapped,
5212 // so there is no harm doing an extra load (also, CSE will later eliminate
5213 // the load entirely).
5214 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
5219 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
5220 if (LI->getOperand(0) == V) return true;
5221 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
5222 if (SI->getOperand(1) == V) return true;
5228 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
5229 Value *Op = LI.getOperand(0);
5231 // load (cast X) --> cast (load X) iff safe
5232 if (CastInst *CI = dyn_cast<CastInst>(Op))
5233 if (Instruction *Res = InstCombineLoadCast(*this, LI))
5236 // None of the following transforms are legal for volatile loads.
5237 if (LI.isVolatile()) return 0;
5239 if (&LI.getParent()->front() != &LI) {
5240 BasicBlock::iterator BBI = &LI; --BBI;
5241 // If the instruction immediately before this is a store to the same
5242 // address, do a simple form of store->load forwarding.
5243 if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
5244 if (SI->getOperand(1) == LI.getOperand(0))
5245 return ReplaceInstUsesWith(LI, SI->getOperand(0));
5246 if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
5247 if (LIB->getOperand(0) == LI.getOperand(0))
5248 return ReplaceInstUsesWith(LI, LIB);
5251 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
5252 if (isa<ConstantPointerNull>(GEPI->getOperand(0)) ||
5253 isa<UndefValue>(GEPI->getOperand(0))) {
5254 // Insert a new store to null instruction before the load to indicate
5255 // that this code is not reachable. We do this instead of inserting
5256 // an unreachable instruction directly because we cannot modify the
5258 new StoreInst(UndefValue::get(LI.getType()),
5259 Constant::getNullValue(Op->getType()), &LI);
5260 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5263 if (Constant *C = dyn_cast<Constant>(Op)) {
5264 // load null/undef -> undef
5265 if ((C->isNullValue() || isa<UndefValue>(C))) {
5266 // Insert a new store to null instruction before the load to indicate that
5267 // this code is not reachable. We do this instead of inserting an
5268 // unreachable instruction directly because we cannot modify the CFG.
5269 new StoreInst(UndefValue::get(LI.getType()),
5270 Constant::getNullValue(Op->getType()), &LI);
5271 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5274 // Instcombine load (constant global) into the value loaded.
5275 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
5276 if (GV->isConstant() && !GV->isExternal())
5277 return ReplaceInstUsesWith(LI, GV->getInitializer());
5279 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
5280 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
5281 if (CE->getOpcode() == Instruction::GetElementPtr) {
5282 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
5283 if (GV->isConstant() && !GV->isExternal())
5285 ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
5286 return ReplaceInstUsesWith(LI, V);
5287 if (CE->getOperand(0)->isNullValue()) {
5288 // Insert a new store to null instruction before the load to indicate
5289 // that this code is not reachable. We do this instead of inserting
5290 // an unreachable instruction directly because we cannot modify the
5292 new StoreInst(UndefValue::get(LI.getType()),
5293 Constant::getNullValue(Op->getType()), &LI);
5294 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5297 } else if (CE->getOpcode() == Instruction::Cast) {
5298 if (Instruction *Res = InstCombineLoadCast(*this, LI))
5303 if (Op->hasOneUse()) {
5304 // Change select and PHI nodes to select values instead of addresses: this
5305 // helps alias analysis out a lot, allows many others simplifications, and
5306 // exposes redundancy in the code.
5308 // Note that we cannot do the transformation unless we know that the
5309 // introduced loads cannot trap! Something like this is valid as long as
5310 // the condition is always false: load (select bool %C, int* null, int* %G),
5311 // but it would not be valid if we transformed it to load from null
5314 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
5315 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
5316 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
5317 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
5318 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
5319 SI->getOperand(1)->getName()+".val"), LI);
5320 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
5321 SI->getOperand(2)->getName()+".val"), LI);
5322 return new SelectInst(SI->getCondition(), V1, V2);
5325 // load (select (cond, null, P)) -> load P
5326 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
5327 if (C->isNullValue()) {
5328 LI.setOperand(0, SI->getOperand(2));
5332 // load (select (cond, P, null)) -> load P
5333 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
5334 if (C->isNullValue()) {
5335 LI.setOperand(0, SI->getOperand(1));
5339 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
5340 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
5341 bool Safe = PN->getParent() == LI.getParent();
5343 // Scan all of the instructions between the PHI and the load to make
5344 // sure there are no instructions that might possibly alter the value
5345 // loaded from the PHI.
5347 BasicBlock::iterator I = &LI;
5348 for (--I; !isa<PHINode>(I); --I)
5349 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
5355 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
5356 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
5357 PN->getIncomingBlock(i)->getTerminator()))
5362 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
5363 InsertNewInstBefore(NewPN, *PN);
5364 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
5366 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
5367 BasicBlock *BB = PN->getIncomingBlock(i);
5368 Value *&TheLoad = LoadMap[BB];
5370 Value *InVal = PN->getIncomingValue(i);
5371 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
5372 InVal->getName()+".val"),
5373 *BB->getTerminator());
5375 NewPN->addIncoming(TheLoad, BB);
5377 return ReplaceInstUsesWith(LI, NewPN);
5384 /// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store (cast V), P'
5386 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
5387 User *CI = cast<User>(SI.getOperand(1));
5388 Value *CastOp = CI->getOperand(0);
5390 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5391 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5392 const Type *SrcPTy = SrcTy->getElementType();
5394 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5395 // If the source is an array, the code below will not succeed. Check to
5396 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5398 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5399 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5400 if (ASrcTy->getNumElements() != 0) {
5401 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5402 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5403 SrcTy = cast<PointerType>(CastOp->getType());
5404 SrcPTy = SrcTy->getElementType();
5407 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5408 IC.getTargetData().getTypeSize(SrcPTy) ==
5409 IC.getTargetData().getTypeSize(DestPTy)) {
5411 // Okay, we are casting from one integer or pointer type to another of
5412 // the same size. Instead of casting the pointer before the store, cast
5413 // the value to be stored.
5415 if (Constant *C = dyn_cast<Constant>(SI.getOperand(0)))
5416 NewCast = ConstantExpr::getCast(C, SrcPTy);
5418 NewCast = IC.InsertNewInstBefore(new CastInst(SI.getOperand(0),
5420 SI.getOperand(0)->getName()+".c"), SI);
5422 return new StoreInst(NewCast, CastOp);
5429 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
5430 Value *Val = SI.getOperand(0);
5431 Value *Ptr = SI.getOperand(1);
5433 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
5434 removeFromWorkList(&SI);
5435 SI.eraseFromParent();
5440 if (SI.isVolatile()) return 0; // Don't hack volatile loads.
5442 // store X, null -> turns into 'unreachable' in SimplifyCFG
5443 if (isa<ConstantPointerNull>(Ptr)) {
5444 if (!isa<UndefValue>(Val)) {
5445 SI.setOperand(0, UndefValue::get(Val->getType()));
5446 if (Instruction *U = dyn_cast<Instruction>(Val))
5447 WorkList.push_back(U); // Dropped a use.
5450 return 0; // Do not modify these!
5453 // store undef, Ptr -> noop
5454 if (isa<UndefValue>(Val)) {
5455 removeFromWorkList(&SI);
5456 SI.eraseFromParent();
5461 // If the pointer destination is a cast, see if we can fold the cast into the
5463 if (CastInst *CI = dyn_cast<CastInst>(Ptr))
5464 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5466 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
5467 if (CE->getOpcode() == Instruction::Cast)
5468 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5472 // If this store is the last instruction in the basic block, and if the block
5473 // ends with an unconditional branch, try to move it to the successor block.
5474 BasicBlock::iterator BBI = &SI; ++BBI;
5475 if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
5476 if (BI->isUnconditional()) {
5477 // Check to see if the successor block has exactly two incoming edges. If
5478 // so, see if the other predecessor contains a store to the same location.
5479 // if so, insert a PHI node (if needed) and move the stores down.
5480 BasicBlock *Dest = BI->getSuccessor(0);
5482 pred_iterator PI = pred_begin(Dest);
5483 BasicBlock *Other = 0;
5484 if (*PI != BI->getParent())
5487 if (PI != pred_end(Dest)) {
5488 if (*PI != BI->getParent())
5493 if (++PI != pred_end(Dest))
5496 if (Other) { // If only one other pred...
5497 BBI = Other->getTerminator();
5498 // Make sure this other block ends in an unconditional branch and that
5499 // there is an instruction before the branch.
5500 if (isa<BranchInst>(BBI) && cast<BranchInst>(BBI)->isUnconditional() &&
5501 BBI != Other->begin()) {
5503 StoreInst *OtherStore = dyn_cast<StoreInst>(BBI);
5505 // If this instruction is a store to the same location.
5506 if (OtherStore && OtherStore->getOperand(1) == SI.getOperand(1)) {
5507 // Okay, we know we can perform this transformation. Insert a PHI
5508 // node now if we need it.
5509 Value *MergedVal = OtherStore->getOperand(0);
5510 if (MergedVal != SI.getOperand(0)) {
5511 PHINode *PN = new PHINode(MergedVal->getType(), "storemerge");
5512 PN->reserveOperandSpace(2);
5513 PN->addIncoming(SI.getOperand(0), SI.getParent());
5514 PN->addIncoming(OtherStore->getOperand(0), Other);
5515 MergedVal = InsertNewInstBefore(PN, Dest->front());
5518 // Advance to a place where it is safe to insert the new store and
5520 BBI = Dest->begin();
5521 while (isa<PHINode>(BBI)) ++BBI;
5522 InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
5523 OtherStore->isVolatile()), *BBI);
5525 // Nuke the old stores.
5526 removeFromWorkList(&SI);
5527 removeFromWorkList(OtherStore);
5528 SI.eraseFromParent();
5529 OtherStore->eraseFromParent();
5541 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
5542 // Change br (not X), label True, label False to: br X, label False, True
5544 BasicBlock *TrueDest;
5545 BasicBlock *FalseDest;
5546 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
5547 !isa<Constant>(X)) {
5548 // Swap Destinations and condition...
5550 BI.setSuccessor(0, FalseDest);
5551 BI.setSuccessor(1, TrueDest);
5555 // Cannonicalize setne -> seteq
5556 Instruction::BinaryOps Op; Value *Y;
5557 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
5558 TrueDest, FalseDest)))
5559 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
5560 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
5561 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
5562 std::string Name = I->getName(); I->setName("");
5563 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
5564 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
5565 // Swap Destinations and condition...
5566 BI.setCondition(NewSCC);
5567 BI.setSuccessor(0, FalseDest);
5568 BI.setSuccessor(1, TrueDest);
5569 removeFromWorkList(I);
5570 I->getParent()->getInstList().erase(I);
5571 WorkList.push_back(cast<Instruction>(NewSCC));
5578 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
5579 Value *Cond = SI.getCondition();
5580 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
5581 if (I->getOpcode() == Instruction::Add)
5582 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
5583 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
5584 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
5585 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
5587 SI.setOperand(0, I->getOperand(0));
5588 WorkList.push_back(I);
5596 void InstCombiner::removeFromWorkList(Instruction *I) {
5597 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
5602 /// TryToSinkInstruction - Try to move the specified instruction from its
5603 /// current block into the beginning of DestBlock, which can only happen if it's
5604 /// safe to move the instruction past all of the instructions between it and the
5605 /// end of its block.
5606 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
5607 assert(I->hasOneUse() && "Invariants didn't hold!");
5609 // Cannot move control-flow-involving instructions.
5610 if (isa<PHINode>(I) || isa<InvokeInst>(I) || isa<CallInst>(I)) return false;
5612 // Do not sink alloca instructions out of the entry block.
5613 if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front())
5616 // We can only sink load instructions if there is nothing between the load and
5617 // the end of block that could change the value.
5618 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
5619 if (LI->isVolatile()) return false; // Don't sink volatile loads.
5621 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
5623 if (Scan->mayWriteToMemory())
5627 BasicBlock::iterator InsertPos = DestBlock->begin();
5628 while (isa<PHINode>(InsertPos)) ++InsertPos;
5630 I->moveBefore(InsertPos);
5635 bool InstCombiner::runOnFunction(Function &F) {
5636 bool Changed = false;
5637 TD = &getAnalysis<TargetData>();
5640 // Populate the worklist with the reachable instructions.
5641 std::set<BasicBlock*> Visited;
5642 for (df_ext_iterator<BasicBlock*> BB = df_ext_begin(&F.front(), Visited),
5643 E = df_ext_end(&F.front(), Visited); BB != E; ++BB)
5644 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
5645 WorkList.push_back(I);
5647 // Do a quick scan over the function. If we find any blocks that are
5648 // unreachable, remove any instructions inside of them. This prevents
5649 // the instcombine code from having to deal with some bad special cases.
5650 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
5651 if (!Visited.count(BB)) {
5652 Instruction *Term = BB->getTerminator();
5653 while (Term != BB->begin()) { // Remove instrs bottom-up
5654 BasicBlock::iterator I = Term; --I;
5656 DEBUG(std::cerr << "IC: DCE: " << *I);
5659 if (!I->use_empty())
5660 I->replaceAllUsesWith(UndefValue::get(I->getType()));
5661 I->eraseFromParent();
5666 while (!WorkList.empty()) {
5667 Instruction *I = WorkList.back(); // Get an instruction from the worklist
5668 WorkList.pop_back();
5670 // Check to see if we can DCE or ConstantPropagate the instruction...
5671 // Check to see if we can DIE the instruction...
5672 if (isInstructionTriviallyDead(I)) {
5673 // Add operands to the worklist...
5674 if (I->getNumOperands() < 4)
5675 AddUsesToWorkList(*I);
5678 DEBUG(std::cerr << "IC: DCE: " << *I);
5680 I->eraseFromParent();
5681 removeFromWorkList(I);
5685 // Instruction isn't dead, see if we can constant propagate it...
5686 if (Constant *C = ConstantFoldInstruction(I)) {
5687 Value* Ptr = I->getOperand(0);
5688 if (isa<GetElementPtrInst>(I) &&
5689 cast<Constant>(Ptr)->isNullValue() &&
5690 !isa<ConstantPointerNull>(C) &&
5691 cast<PointerType>(Ptr->getType())->getElementType()->isSized()) {
5692 // If this is a constant expr gep that is effectively computing an
5693 // "offsetof", fold it into 'cast int X to T*' instead of 'gep 0, 0, 12'
5694 bool isFoldableGEP = true;
5695 for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
5696 if (!isa<ConstantInt>(I->getOperand(i)))
5697 isFoldableGEP = false;
5698 if (isFoldableGEP) {
5699 uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
5700 std::vector<Value*>(I->op_begin()+1, I->op_end()));
5701 C = ConstantUInt::get(Type::ULongTy, Offset);
5702 C = ConstantExpr::getCast(C, TD->getIntPtrType());
5703 C = ConstantExpr::getCast(C, I->getType());
5707 DEBUG(std::cerr << "IC: ConstFold to: " << *C << " from: " << *I);
5709 // Add operands to the worklist...
5710 AddUsesToWorkList(*I);
5711 ReplaceInstUsesWith(*I, C);
5714 I->getParent()->getInstList().erase(I);
5715 removeFromWorkList(I);
5719 // See if we can trivially sink this instruction to a successor basic block.
5720 if (I->hasOneUse()) {
5721 BasicBlock *BB = I->getParent();
5722 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
5723 if (UserParent != BB) {
5724 bool UserIsSuccessor = false;
5725 // See if the user is one of our successors.
5726 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
5727 if (*SI == UserParent) {
5728 UserIsSuccessor = true;
5732 // If the user is one of our immediate successors, and if that successor
5733 // only has us as a predecessors (we'd have to split the critical edge
5734 // otherwise), we can keep going.
5735 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
5736 next(pred_begin(UserParent)) == pred_end(UserParent))
5737 // Okay, the CFG is simple enough, try to sink this instruction.
5738 Changed |= TryToSinkInstruction(I, UserParent);
5742 // Now that we have an instruction, try combining it to simplify it...
5743 if (Instruction *Result = visit(*I)) {
5745 // Should we replace the old instruction with a new one?
5747 DEBUG(std::cerr << "IC: Old = " << *I
5748 << " New = " << *Result);
5750 // Everything uses the new instruction now.
5751 I->replaceAllUsesWith(Result);
5753 // Push the new instruction and any users onto the worklist.
5754 WorkList.push_back(Result);
5755 AddUsersToWorkList(*Result);
5757 // Move the name to the new instruction first...
5758 std::string OldName = I->getName(); I->setName("");
5759 Result->setName(OldName);
5761 // Insert the new instruction into the basic block...
5762 BasicBlock *InstParent = I->getParent();
5763 BasicBlock::iterator InsertPos = I;
5765 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
5766 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
5769 InstParent->getInstList().insert(InsertPos, Result);
5771 // Make sure that we reprocess all operands now that we reduced their
5773 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
5774 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
5775 WorkList.push_back(OpI);
5777 // Instructions can end up on the worklist more than once. Make sure
5778 // we do not process an instruction that has been deleted.
5779 removeFromWorkList(I);
5781 // Erase the old instruction.
5782 InstParent->getInstList().erase(I);
5784 DEBUG(std::cerr << "IC: MOD = " << *I);
5786 // If the instruction was modified, it's possible that it is now dead.
5787 // if so, remove it.
5788 if (isInstructionTriviallyDead(I)) {
5789 // Make sure we process all operands now that we are reducing their
5791 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
5792 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
5793 WorkList.push_back(OpI);
5795 // Instructions may end up in the worklist more than once. Erase all
5796 // occurrances of this instruction.
5797 removeFromWorkList(I);
5798 I->eraseFromParent();
5800 WorkList.push_back(Result);
5801 AddUsersToWorkList(*Result);
5811 FunctionPass *llvm::createInstructionCombiningPass() {
5812 return new InstCombiner();