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 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
389 // true when both operands are equal...
391 static bool isTrueWhenEqual(Instruction &I) {
392 return I.getOpcode() == Instruction::SetEQ ||
393 I.getOpcode() == Instruction::SetGE ||
394 I.getOpcode() == Instruction::SetLE;
397 /// AssociativeOpt - Perform an optimization on an associative operator. This
398 /// function is designed to check a chain of associative operators for a
399 /// potential to apply a certain optimization. Since the optimization may be
400 /// applicable if the expression was reassociated, this checks the chain, then
401 /// reassociates the expression as necessary to expose the optimization
402 /// opportunity. This makes use of a special Functor, which must define
403 /// 'shouldApply' and 'apply' methods.
405 template<typename Functor>
406 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
407 unsigned Opcode = Root.getOpcode();
408 Value *LHS = Root.getOperand(0);
410 // Quick check, see if the immediate LHS matches...
411 if (F.shouldApply(LHS))
412 return F.apply(Root);
414 // Otherwise, if the LHS is not of the same opcode as the root, return.
415 Instruction *LHSI = dyn_cast<Instruction>(LHS);
416 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
417 // Should we apply this transform to the RHS?
418 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
420 // If not to the RHS, check to see if we should apply to the LHS...
421 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
422 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
426 // If the functor wants to apply the optimization to the RHS of LHSI,
427 // reassociate the expression from ((? op A) op B) to (? op (A op B))
429 BasicBlock *BB = Root.getParent();
431 // Now all of the instructions are in the current basic block, go ahead
432 // and perform the reassociation.
433 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
435 // First move the selected RHS to the LHS of the root...
436 Root.setOperand(0, LHSI->getOperand(1));
438 // Make what used to be the LHS of the root be the user of the root...
439 Value *ExtraOperand = TmpLHSI->getOperand(1);
440 if (&Root == TmpLHSI) {
441 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
444 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
445 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
446 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
447 BasicBlock::iterator ARI = &Root; ++ARI;
448 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
451 // Now propagate the ExtraOperand down the chain of instructions until we
453 while (TmpLHSI != LHSI) {
454 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
455 // Move the instruction to immediately before the chain we are
456 // constructing to avoid breaking dominance properties.
457 NextLHSI->getParent()->getInstList().remove(NextLHSI);
458 BB->getInstList().insert(ARI, NextLHSI);
461 Value *NextOp = NextLHSI->getOperand(1);
462 NextLHSI->setOperand(1, ExtraOperand);
464 ExtraOperand = NextOp;
467 // Now that the instructions are reassociated, have the functor perform
468 // the transformation...
469 return F.apply(Root);
472 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
478 // AddRHS - Implements: X + X --> X << 1
481 AddRHS(Value *rhs) : RHS(rhs) {}
482 bool shouldApply(Value *LHS) const { return LHS == RHS; }
483 Instruction *apply(BinaryOperator &Add) const {
484 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
485 ConstantInt::get(Type::UByteTy, 1));
489 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
491 struct AddMaskingAnd {
493 AddMaskingAnd(Constant *c) : C2(c) {}
494 bool shouldApply(Value *LHS) const {
496 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
497 ConstantExpr::getAnd(C1, C2)->isNullValue();
499 Instruction *apply(BinaryOperator &Add) const {
500 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
504 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
506 if (isa<CastInst>(I)) {
507 if (Constant *SOC = dyn_cast<Constant>(SO))
508 return ConstantExpr::getCast(SOC, I.getType());
510 return IC->InsertNewInstBefore(new CastInst(SO, I.getType(),
511 SO->getName() + ".cast"), I);
514 // Figure out if the constant is the left or the right argument.
515 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
516 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
518 if (Constant *SOC = dyn_cast<Constant>(SO)) {
520 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
521 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
524 Value *Op0 = SO, *Op1 = ConstOperand;
528 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
529 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
530 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&I))
531 New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh");
533 assert(0 && "Unknown binary instruction type!");
536 return IC->InsertNewInstBefore(New, I);
539 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
540 // constant as the other operand, try to fold the binary operator into the
541 // select arguments. This also works for Cast instructions, which obviously do
542 // not have a second operand.
543 static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
545 // Don't modify shared select instructions
546 if (!SI->hasOneUse()) return 0;
547 Value *TV = SI->getOperand(1);
548 Value *FV = SI->getOperand(2);
550 if (isa<Constant>(TV) || isa<Constant>(FV)) {
551 // Bool selects with constant operands can be folded to logical ops.
552 if (SI->getType() == Type::BoolTy) return 0;
554 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
555 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
557 return new SelectInst(SI->getCondition(), SelectTrueVal,
564 /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
565 /// node as operand #0, see if we can fold the instruction into the PHI (which
566 /// is only possible if all operands to the PHI are constants).
567 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
568 PHINode *PN = cast<PHINode>(I.getOperand(0));
569 unsigned NumPHIValues = PN->getNumIncomingValues();
570 if (!PN->hasOneUse() || NumPHIValues == 0 ||
571 !isa<Constant>(PN->getIncomingValue(0))) return 0;
573 // Check to see if all of the operands of the PHI are constants. If not, we
574 // cannot do the transformation.
575 for (unsigned i = 1; i != NumPHIValues; ++i)
576 if (!isa<Constant>(PN->getIncomingValue(i)))
579 // Okay, we can do the transformation: create the new PHI node.
580 PHINode *NewPN = new PHINode(I.getType(), I.getName());
582 NewPN->reserveOperandSpace(PN->getNumOperands()/2);
583 InsertNewInstBefore(NewPN, *PN);
585 // Next, add all of the operands to the PHI.
586 if (I.getNumOperands() == 2) {
587 Constant *C = cast<Constant>(I.getOperand(1));
588 for (unsigned i = 0; i != NumPHIValues; ++i) {
589 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
590 NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
591 PN->getIncomingBlock(i));
594 assert(isa<CastInst>(I) && "Unary op should be a cast!");
595 const Type *RetTy = I.getType();
596 for (unsigned i = 0; i != NumPHIValues; ++i) {
597 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
598 NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
599 PN->getIncomingBlock(i));
602 return ReplaceInstUsesWith(I, NewPN);
605 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
606 bool Changed = SimplifyCommutative(I);
607 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
609 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
610 // X + undef -> undef
611 if (isa<UndefValue>(RHS))
612 return ReplaceInstUsesWith(I, RHS);
615 if (!I.getType()->isFloatingPoint() && // -0 + +0 = +0, so it's not a noop
617 return ReplaceInstUsesWith(I, LHS);
619 // X + (signbit) --> X ^ signbit
620 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
621 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
622 uint64_t Val = CI->getRawValue() & (1ULL << NumBits)-1;
623 if (Val == (1ULL << (NumBits-1)))
624 return BinaryOperator::createXor(LHS, RHS);
627 if (isa<PHINode>(LHS))
628 if (Instruction *NV = FoldOpIntoPhi(I))
633 if (I.getType()->isInteger()) {
634 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
636 if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
637 if (RHSI->getOpcode() == Instruction::Sub)
638 if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
639 return ReplaceInstUsesWith(I, RHSI->getOperand(0));
641 if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
642 if (LHSI->getOpcode() == Instruction::Sub)
643 if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
644 return ReplaceInstUsesWith(I, LHSI->getOperand(0));
649 if (Value *V = dyn_castNegVal(LHS))
650 return BinaryOperator::createSub(RHS, V);
653 if (!isa<Constant>(RHS))
654 if (Value *V = dyn_castNegVal(RHS))
655 return BinaryOperator::createSub(LHS, V);
659 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
660 if (X == RHS) // X*C + X --> X * (C+1)
661 return BinaryOperator::createMul(RHS, AddOne(C2));
663 // X*C1 + X*C2 --> X * (C1+C2)
665 if (X == dyn_castFoldableMul(RHS, C1))
666 return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2));
669 // X + X*C --> X * (C+1)
670 if (dyn_castFoldableMul(RHS, C2) == LHS)
671 return BinaryOperator::createMul(LHS, AddOne(C2));
674 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
675 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
676 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
678 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
680 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
681 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
682 return BinaryOperator::createSub(C, X);
685 // (X & FF00) + xx00 -> (X+xx00) & FF00
686 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
687 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
689 // See if all bits from the first bit set in the Add RHS up are included
690 // in the mask. First, get the rightmost bit.
691 uint64_t AddRHSV = CRHS->getRawValue();
693 // Form a mask of all bits from the lowest bit added through the top.
694 uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
695 AddRHSHighBits &= ~0ULL >> (64-C2->getType()->getPrimitiveSizeInBits());
697 // See if the and mask includes all of these bits.
698 uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue();
700 if (AddRHSHighBits == AddRHSHighBitsAnd) {
701 // Okay, the xform is safe. Insert the new add pronto.
702 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
704 return BinaryOperator::createAnd(NewAdd, C2);
709 // Try to fold constant add into select arguments.
710 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
711 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
715 return Changed ? &I : 0;
718 // isSignBit - Return true if the value represented by the constant only has the
719 // highest order bit set.
720 static bool isSignBit(ConstantInt *CI) {
721 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
722 return (CI->getRawValue() & (~0ULL >> (64-NumBits))) == (1ULL << (NumBits-1));
725 /// RemoveNoopCast - Strip off nonconverting casts from the value.
727 static Value *RemoveNoopCast(Value *V) {
728 if (CastInst *CI = dyn_cast<CastInst>(V)) {
729 const Type *CTy = CI->getType();
730 const Type *OpTy = CI->getOperand(0)->getType();
731 if (CTy->isInteger() && OpTy->isInteger()) {
732 if (CTy->getPrimitiveSizeInBits() == OpTy->getPrimitiveSizeInBits())
733 return RemoveNoopCast(CI->getOperand(0));
734 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
735 return RemoveNoopCast(CI->getOperand(0));
740 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
741 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
743 if (Op0 == Op1) // sub X, X -> 0
744 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
746 // If this is a 'B = x-(-A)', change to B = x+A...
747 if (Value *V = dyn_castNegVal(Op1))
748 return BinaryOperator::createAdd(Op0, V);
750 if (isa<UndefValue>(Op0))
751 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
752 if (isa<UndefValue>(Op1))
753 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
755 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
756 // Replace (-1 - A) with (~A)...
757 if (C->isAllOnesValue())
758 return BinaryOperator::createNot(Op1);
760 // C - ~X == X + (1+C)
762 if (match(Op1, m_Not(m_Value(X))))
763 return BinaryOperator::createAdd(X,
764 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
765 // -((uint)X >> 31) -> ((int)X >> 31)
766 // -((int)X >> 31) -> ((uint)X >> 31)
767 if (C->isNullValue()) {
768 Value *NoopCastedRHS = RemoveNoopCast(Op1);
769 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
770 if (SI->getOpcode() == Instruction::Shr)
771 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
773 if (SI->getType()->isSigned())
774 NewTy = SI->getType()->getUnsignedVersion();
776 NewTy = SI->getType()->getSignedVersion();
777 // Check to see if we are shifting out everything but the sign bit.
778 if (CU->getValue() == SI->getType()->getPrimitiveSizeInBits()-1) {
779 // Ok, the transformation is safe. Insert a cast of the incoming
780 // value, then the new shift, then the new cast.
781 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
782 SI->getOperand(0)->getName());
783 Value *InV = InsertNewInstBefore(FirstCast, I);
784 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
786 if (NewShift->getType() == I.getType())
789 InV = InsertNewInstBefore(NewShift, I);
790 return new CastInst(NewShift, I.getType());
796 // Try to fold constant sub into select arguments.
797 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
798 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
801 if (isa<PHINode>(Op0))
802 if (Instruction *NV = FoldOpIntoPhi(I))
806 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
807 if (Op1I->getOpcode() == Instruction::Add &&
808 !Op0->getType()->isFloatingPoint()) {
809 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
810 return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
811 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
812 return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
813 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
814 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
815 // C1-(X+C2) --> (C1-C2)-X
816 return BinaryOperator::createSub(ConstantExpr::getSub(CI1, CI2),
817 Op1I->getOperand(0));
821 if (Op1I->hasOneUse()) {
822 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
823 // is not used by anyone else...
825 if (Op1I->getOpcode() == Instruction::Sub &&
826 !Op1I->getType()->isFloatingPoint()) {
827 // Swap the two operands of the subexpr...
828 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
829 Op1I->setOperand(0, IIOp1);
830 Op1I->setOperand(1, IIOp0);
832 // Create the new top level add instruction...
833 return BinaryOperator::createAdd(Op0, Op1);
836 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
838 if (Op1I->getOpcode() == Instruction::And &&
839 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
840 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
843 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
844 return BinaryOperator::createAnd(Op0, NewNot);
847 // -(X sdiv C) -> (X sdiv -C)
848 if (Op1I->getOpcode() == Instruction::Div)
849 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
850 if (CSI->isNullValue())
851 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
852 return BinaryOperator::createDiv(Op1I->getOperand(0),
853 ConstantExpr::getNeg(DivRHS));
855 // X - X*C --> X * (1-C)
857 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
859 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
860 return BinaryOperator::createMul(Op0, CP1);
865 if (!Op0->getType()->isFloatingPoint())
866 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
867 if (Op0I->getOpcode() == Instruction::Add) {
868 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
869 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
870 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
871 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
872 } else if (Op0I->getOpcode() == Instruction::Sub) {
873 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
874 return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName());
878 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
879 if (X == Op1) { // X*C - X --> X * (C-1)
880 Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
881 return BinaryOperator::createMul(Op1, CP1);
884 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
885 if (X == dyn_castFoldableMul(Op1, C2))
886 return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
891 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
892 /// really just returns true if the most significant (sign) bit is set.
893 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
894 if (RHS->getType()->isSigned()) {
895 // True if source is LHS < 0 or LHS <= -1
896 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
897 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
899 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
900 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
901 // the size of the integer type.
902 if (Opcode == Instruction::SetGE)
903 return RHSC->getValue() ==
904 1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1);
905 if (Opcode == Instruction::SetGT)
906 return RHSC->getValue() ==
907 (1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1))-1;
912 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
913 bool Changed = SimplifyCommutative(I);
914 Value *Op0 = I.getOperand(0);
916 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
917 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
919 // Simplify mul instructions with a constant RHS...
920 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
921 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
923 // ((X << C1)*C2) == (X * (C2 << C1))
924 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
925 if (SI->getOpcode() == Instruction::Shl)
926 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
927 return BinaryOperator::createMul(SI->getOperand(0),
928 ConstantExpr::getShl(CI, ShOp));
930 if (CI->isNullValue())
931 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
932 if (CI->equalsInt(1)) // X * 1 == X
933 return ReplaceInstUsesWith(I, Op0);
934 if (CI->isAllOnesValue()) // X * -1 == 0 - X
935 return BinaryOperator::createNeg(Op0, I.getName());
937 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
938 if (isPowerOf2_64(Val)) { // Replace X*(2^C) with X << C
939 uint64_t C = Log2_64(Val);
940 return new ShiftInst(Instruction::Shl, Op0,
941 ConstantUInt::get(Type::UByteTy, C));
943 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
944 if (Op1F->isNullValue())
945 return ReplaceInstUsesWith(I, Op1);
947 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
948 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
949 if (Op1F->getValue() == 1.0)
950 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
953 // Try to fold constant mul into select arguments.
954 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
955 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
958 if (isa<PHINode>(Op0))
959 if (Instruction *NV = FoldOpIntoPhi(I))
963 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
964 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
965 return BinaryOperator::createMul(Op0v, Op1v);
967 // If one of the operands of the multiply is a cast from a boolean value, then
968 // we know the bool is either zero or one, so this is a 'masking' multiply.
969 // See if we can simplify things based on how the boolean was originally
971 CastInst *BoolCast = 0;
972 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
973 if (CI->getOperand(0)->getType() == Type::BoolTy)
976 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
977 if (CI->getOperand(0)->getType() == Type::BoolTy)
980 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
981 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
982 const Type *SCOpTy = SCIOp0->getType();
984 // If the setcc is true iff the sign bit of X is set, then convert this
985 // multiply into a shift/and combination.
986 if (isa<ConstantInt>(SCIOp1) &&
987 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
988 // Shift the X value right to turn it into "all signbits".
989 Constant *Amt = ConstantUInt::get(Type::UByteTy,
990 SCOpTy->getPrimitiveSizeInBits()-1);
991 if (SCIOp0->getType()->isUnsigned()) {
992 const Type *NewTy = SCIOp0->getType()->getSignedVersion();
993 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
994 SCIOp0->getName()), I);
998 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
999 BoolCast->getOperand(0)->getName()+
1002 // If the multiply type is not the same as the source type, sign extend
1003 // or truncate to the multiply type.
1004 if (I.getType() != V->getType())
1005 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
1007 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
1008 return BinaryOperator::createAnd(V, OtherOp);
1013 return Changed ? &I : 0;
1016 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
1017 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1019 if (isa<UndefValue>(Op0)) // undef / X -> 0
1020 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1021 if (isa<UndefValue>(Op1))
1022 return ReplaceInstUsesWith(I, Op1); // X / undef -> undef
1024 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1026 if (RHS->equalsInt(1))
1027 return ReplaceInstUsesWith(I, Op0);
1030 if (RHS->isAllOnesValue())
1031 return BinaryOperator::createNeg(Op0);
1033 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
1034 if (LHS->getOpcode() == Instruction::Div)
1035 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
1036 // (X / C1) / C2 -> X / (C1*C2)
1037 return BinaryOperator::createDiv(LHS->getOperand(0),
1038 ConstantExpr::getMul(RHS, LHSRHS));
1041 // Check to see if this is an unsigned division with an exact power of 2,
1042 // if so, convert to a right shift.
1043 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1044 if (uint64_t Val = C->getValue()) // Don't break X / 0
1045 if (isPowerOf2_64(Val)) {
1046 uint64_t C = Log2_64(Val);
1047 return new ShiftInst(Instruction::Shr, Op0,
1048 ConstantUInt::get(Type::UByteTy, C));
1052 if (RHS->getType()->isSigned())
1053 if (Value *LHSNeg = dyn_castNegVal(Op0))
1054 return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS));
1056 if (!RHS->isNullValue()) {
1057 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1058 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1060 if (isa<PHINode>(Op0))
1061 if (Instruction *NV = FoldOpIntoPhi(I))
1066 // If this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1067 // transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'.
1068 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1069 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1070 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1071 if (STO->getValue() == 0) { // Couldn't be this argument.
1072 I.setOperand(1, SFO);
1074 } else if (SFO->getValue() == 0) {
1075 I.setOperand(1, STO);
1079 uint64_t TVA = STO->getValue(), FVA = SFO->getValue();
1080 if (isPowerOf2_64(TVA) && isPowerOf2_64(FVA)) {
1081 unsigned TSA = Log2_64(TVA), FSA = Log2_64(FVA);
1082 Constant *TC = ConstantUInt::get(Type::UByteTy, TSA);
1083 Instruction *TSI = new ShiftInst(Instruction::Shr, Op0,
1084 TC, SI->getName()+".t");
1085 TSI = InsertNewInstBefore(TSI, I);
1087 Constant *FC = ConstantUInt::get(Type::UByteTy, FSA);
1088 Instruction *FSI = new ShiftInst(Instruction::Shr, Op0,
1089 FC, SI->getName()+".f");
1090 FSI = InsertNewInstBefore(FSI, I);
1091 return new SelectInst(SI->getOperand(0), TSI, FSI);
1095 // 0 / X == 0, we don't need to preserve faults!
1096 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1097 if (LHS->equalsInt(0))
1098 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1104 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
1105 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1106 if (I.getType()->isSigned())
1107 if (Value *RHSNeg = dyn_castNegVal(Op1))
1108 if (!isa<ConstantSInt>(RHSNeg) ||
1109 cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
1111 AddUsesToWorkList(I);
1112 I.setOperand(1, RHSNeg);
1116 if (isa<UndefValue>(Op0)) // undef % X -> 0
1117 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1118 if (isa<UndefValue>(Op1))
1119 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
1121 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1122 if (RHS->equalsInt(1)) // X % 1 == 0
1123 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1125 // Check to see if this is an unsigned remainder with an exact power of 2,
1126 // if so, convert to a bitwise and.
1127 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1128 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
1129 if (!(Val & (Val-1))) // Power of 2
1130 return BinaryOperator::createAnd(Op0,
1131 ConstantUInt::get(I.getType(), Val-1));
1133 if (!RHS->isNullValue()) {
1134 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1135 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1137 if (isa<PHINode>(Op0))
1138 if (Instruction *NV = FoldOpIntoPhi(I))
1143 // If this is 'urem X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1144 // transform this into: '(Cond ? (urem X, C1) : (urem X, C2))'.
1145 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1146 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1147 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1148 if (STO->getValue() == 0) { // Couldn't be this argument.
1149 I.setOperand(1, SFO);
1151 } else if (SFO->getValue() == 0) {
1152 I.setOperand(1, STO);
1156 if (!(STO->getValue() & (STO->getValue()-1)) &&
1157 !(SFO->getValue() & (SFO->getValue()-1))) {
1158 Value *TrueAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1159 SubOne(STO), SI->getName()+".t"), I);
1160 Value *FalseAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1161 SubOne(SFO), SI->getName()+".f"), I);
1162 return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
1166 // 0 % X == 0, we don't need to preserve faults!
1167 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1168 if (LHS->equalsInt(0))
1169 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1174 // isMaxValueMinusOne - return true if this is Max-1
1175 static bool isMaxValueMinusOne(const ConstantInt *C) {
1176 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
1177 // Calculate -1 casted to the right type...
1178 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1179 uint64_t Val = ~0ULL; // All ones
1180 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1181 return CU->getValue() == Val-1;
1184 const ConstantSInt *CS = cast<ConstantSInt>(C);
1186 // Calculate 0111111111..11111
1187 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1188 int64_t Val = INT64_MAX; // All ones
1189 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1190 return CS->getValue() == Val-1;
1193 // isMinValuePlusOne - return true if this is Min+1
1194 static bool isMinValuePlusOne(const ConstantInt *C) {
1195 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1196 return CU->getValue() == 1;
1198 const ConstantSInt *CS = cast<ConstantSInt>(C);
1200 // Calculate 1111111111000000000000
1201 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1202 int64_t Val = -1; // All ones
1203 Val <<= TypeBits-1; // Shift over to the right spot
1204 return CS->getValue() == Val+1;
1207 // isOneBitSet - Return true if there is exactly one bit set in the specified
1209 static bool isOneBitSet(const ConstantInt *CI) {
1210 uint64_t V = CI->getRawValue();
1211 return V && (V & (V-1)) == 0;
1214 #if 0 // Currently unused
1215 // isLowOnes - Return true if the constant is of the form 0+1+.
1216 static bool isLowOnes(const ConstantInt *CI) {
1217 uint64_t V = CI->getRawValue();
1219 // There won't be bits set in parts that the type doesn't contain.
1220 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1222 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1223 return U && V && (U & V) == 0;
1227 // isHighOnes - Return true if the constant is of the form 1+0+.
1228 // This is the same as lowones(~X).
1229 static bool isHighOnes(const ConstantInt *CI) {
1230 uint64_t V = ~CI->getRawValue();
1231 if (~V == 0) return false; // 0's does not match "1+"
1233 // There won't be bits set in parts that the type doesn't contain.
1234 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1236 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1237 return U && V && (U & V) == 0;
1241 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
1242 /// are carefully arranged to allow folding of expressions such as:
1244 /// (A < B) | (A > B) --> (A != B)
1246 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
1247 /// represents that the comparison is true if A == B, and bit value '1' is true
1250 static unsigned getSetCondCode(const SetCondInst *SCI) {
1251 switch (SCI->getOpcode()) {
1253 case Instruction::SetGT: return 1;
1254 case Instruction::SetEQ: return 2;
1255 case Instruction::SetGE: return 3;
1256 case Instruction::SetLT: return 4;
1257 case Instruction::SetNE: return 5;
1258 case Instruction::SetLE: return 6;
1261 assert(0 && "Invalid SetCC opcode!");
1266 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
1267 /// opcode and two operands into either a constant true or false, or a brand new
1268 /// SetCC instruction.
1269 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
1271 case 0: return ConstantBool::False;
1272 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
1273 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
1274 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
1275 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
1276 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
1277 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
1278 case 7: return ConstantBool::True;
1279 default: assert(0 && "Illegal SetCCCode!"); return 0;
1283 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1284 struct FoldSetCCLogical {
1287 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
1288 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
1289 bool shouldApply(Value *V) const {
1290 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
1291 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
1292 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
1295 Instruction *apply(BinaryOperator &Log) const {
1296 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
1297 if (SCI->getOperand(0) != LHS) {
1298 assert(SCI->getOperand(1) == LHS);
1299 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
1302 unsigned LHSCode = getSetCondCode(SCI);
1303 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
1305 switch (Log.getOpcode()) {
1306 case Instruction::And: Code = LHSCode & RHSCode; break;
1307 case Instruction::Or: Code = LHSCode | RHSCode; break;
1308 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
1309 default: assert(0 && "Illegal logical opcode!"); return 0;
1312 Value *RV = getSetCCValue(Code, LHS, RHS);
1313 if (Instruction *I = dyn_cast<Instruction>(RV))
1315 // Otherwise, it's a constant boolean value...
1316 return IC.ReplaceInstUsesWith(Log, RV);
1321 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
1322 /// this predicate to simplify operations downstream. V and Mask are known to
1323 /// be the same type.
1324 static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask) {
1325 // Note, we cannot consider 'undef' to be "IsZero" here. The problem is that
1326 // we cannot optimize based on the assumption that it is zero without changing
1327 // to to an explicit zero. If we don't change it to zero, other code could
1328 // optimized based on the contradictory assumption that it is non-zero.
1329 // Because instcombine aggressively folds operations with undef args anyway,
1330 // this won't lose us code quality.
1331 if (Mask->isNullValue())
1333 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
1334 return ConstantExpr::getAnd(CI, Mask)->isNullValue();
1336 if (Instruction *I = dyn_cast<Instruction>(V)) {
1337 switch (I->getOpcode()) {
1338 case Instruction::And:
1339 // (X & C1) & C2 == 0 iff C1 & C2 == 0.
1340 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1)))
1341 if (ConstantExpr::getAnd(CI, Mask)->isNullValue())
1344 case Instruction::Or:
1345 // If the LHS and the RHS are MaskedValueIsZero, the result is also zero.
1346 return MaskedValueIsZero(I->getOperand(1), Mask) &&
1347 MaskedValueIsZero(I->getOperand(0), Mask);
1348 case Instruction::Select:
1349 // If the T and F values are MaskedValueIsZero, the result is also zero.
1350 return MaskedValueIsZero(I->getOperand(2), Mask) &&
1351 MaskedValueIsZero(I->getOperand(1), Mask);
1352 case Instruction::Cast: {
1353 const Type *SrcTy = I->getOperand(0)->getType();
1354 if (SrcTy == Type::BoolTy)
1355 return (Mask->getRawValue() & 1) == 0;
1357 if (SrcTy->isInteger()) {
1358 // (cast <ty> X to int) & C2 == 0 iff <ty> could not have contained C2.
1359 if (SrcTy->isUnsigned() && // Only handle zero ext.
1360 ConstantExpr::getCast(Mask, SrcTy)->isNullValue())
1363 // If this is a noop cast, recurse.
1364 if ((SrcTy->isSigned() && SrcTy->getUnsignedVersion() == I->getType())||
1365 SrcTy->getSignedVersion() == I->getType()) {
1367 ConstantExpr::getCast(Mask, I->getOperand(0)->getType());
1368 return MaskedValueIsZero(I->getOperand(0),
1369 cast<ConstantIntegral>(NewMask));
1374 case Instruction::Shl:
1375 // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
1376 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
1377 return MaskedValueIsZero(I->getOperand(0),
1378 cast<ConstantIntegral>(ConstantExpr::getUShr(Mask, SA)));
1380 case Instruction::Shr:
1381 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
1382 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
1383 if (I->getType()->isUnsigned()) {
1384 Constant *C1 = ConstantIntegral::getAllOnesValue(I->getType());
1385 C1 = ConstantExpr::getShr(C1, SA);
1386 C1 = ConstantExpr::getAnd(C1, Mask);
1387 if (C1->isNullValue())
1397 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
1398 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
1399 // guaranteed to be either a shift instruction or a binary operator.
1400 Instruction *InstCombiner::OptAndOp(Instruction *Op,
1401 ConstantIntegral *OpRHS,
1402 ConstantIntegral *AndRHS,
1403 BinaryOperator &TheAnd) {
1404 Value *X = Op->getOperand(0);
1405 Constant *Together = 0;
1406 if (!isa<ShiftInst>(Op))
1407 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
1409 switch (Op->getOpcode()) {
1410 case Instruction::Xor:
1411 if (Op->hasOneUse()) {
1412 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
1413 std::string OpName = Op->getName(); Op->setName("");
1414 Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
1415 InsertNewInstBefore(And, TheAnd);
1416 return BinaryOperator::createXor(And, Together);
1419 case Instruction::Or:
1420 if (Together == AndRHS) // (X | C) & C --> C
1421 return ReplaceInstUsesWith(TheAnd, AndRHS);
1423 if (Op->hasOneUse() && Together != OpRHS) {
1424 // (X | C1) & C2 --> (X | (C1&C2)) & C2
1425 std::string Op0Name = Op->getName(); Op->setName("");
1426 Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
1427 InsertNewInstBefore(Or, TheAnd);
1428 return BinaryOperator::createAnd(Or, AndRHS);
1431 case Instruction::Add:
1432 if (Op->hasOneUse()) {
1433 // Adding a one to a single bit bit-field should be turned into an XOR
1434 // of the bit. First thing to check is to see if this AND is with a
1435 // single bit constant.
1436 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
1438 // Clear bits that are not part of the constant.
1439 AndRHSV &= ~0ULL >> (64-AndRHS->getType()->getPrimitiveSizeInBits());
1441 // If there is only one bit set...
1442 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
1443 // Ok, at this point, we know that we are masking the result of the
1444 // ADD down to exactly one bit. If the constant we are adding has
1445 // no bits set below this bit, then we can eliminate the ADD.
1446 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
1448 // Check to see if any bits below the one bit set in AndRHSV are set.
1449 if ((AddRHS & (AndRHSV-1)) == 0) {
1450 // If not, the only thing that can effect the output of the AND is
1451 // the bit specified by AndRHSV. If that bit is set, the effect of
1452 // the XOR is to toggle the bit. If it is clear, then the ADD has
1454 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
1455 TheAnd.setOperand(0, X);
1458 std::string Name = Op->getName(); Op->setName("");
1459 // Pull the XOR out of the AND.
1460 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
1461 InsertNewInstBefore(NewAnd, TheAnd);
1462 return BinaryOperator::createXor(NewAnd, AndRHS);
1469 case Instruction::Shl: {
1470 // We know that the AND will not produce any of the bits shifted in, so if
1471 // the anded constant includes them, clear them now!
1473 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1474 Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
1475 Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
1477 if (CI == ShlMask) { // Masking out bits that the shift already masks
1478 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
1479 } else if (CI != AndRHS) { // Reducing bits set in and.
1480 TheAnd.setOperand(1, CI);
1485 case Instruction::Shr:
1486 // We know that the AND will not produce any of the bits shifted in, so if
1487 // the anded constant includes them, clear them now! This only applies to
1488 // unsigned shifts, because a signed shr may bring in set bits!
1490 if (AndRHS->getType()->isUnsigned()) {
1491 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1492 Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS);
1493 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1495 if (CI == ShrMask) { // Masking out bits that the shift already masks.
1496 return ReplaceInstUsesWith(TheAnd, Op);
1497 } else if (CI != AndRHS) {
1498 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
1501 } else { // Signed shr.
1502 // See if this is shifting in some sign extension, then masking it out
1504 if (Op->hasOneUse()) {
1505 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1506 Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS);
1507 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1508 if (CI == AndRHS) { // Masking out bits shifted in.
1509 // Make the argument unsigned.
1510 Value *ShVal = Op->getOperand(0);
1511 ShVal = InsertCastBefore(ShVal,
1512 ShVal->getType()->getUnsignedVersion(),
1514 ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal,
1515 OpRHS, Op->getName()),
1517 Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType());
1518 ShVal = InsertNewInstBefore(BinaryOperator::createAnd(ShVal, AndRHS2,
1521 return new CastInst(ShVal, Op->getType());
1531 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
1532 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
1533 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. IB is the location to
1534 /// insert new instructions.
1535 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
1536 bool Inside, Instruction &IB) {
1537 assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
1538 "Lo is not <= Hi in range emission code!");
1540 if (Lo == Hi) // Trivially false.
1541 return new SetCondInst(Instruction::SetNE, V, V);
1542 if (cast<ConstantIntegral>(Lo)->isMinValue())
1543 return new SetCondInst(Instruction::SetLT, V, Hi);
1545 Constant *AddCST = ConstantExpr::getNeg(Lo);
1546 Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
1547 InsertNewInstBefore(Add, IB);
1548 // Convert to unsigned for the comparison.
1549 const Type *UnsType = Add->getType()->getUnsignedVersion();
1550 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1551 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1552 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1553 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1556 if (Lo == Hi) // Trivially true.
1557 return new SetCondInst(Instruction::SetEQ, V, V);
1559 Hi = SubOne(cast<ConstantInt>(Hi));
1560 if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
1561 return new SetCondInst(Instruction::SetGT, V, Hi);
1563 // Emit X-Lo > Hi-Lo-1
1564 Constant *AddCST = ConstantExpr::getNeg(Lo);
1565 Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
1566 InsertNewInstBefore(Add, IB);
1567 // Convert to unsigned for the comparison.
1568 const Type *UnsType = Add->getType()->getUnsignedVersion();
1569 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1570 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1571 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1572 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1575 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
1576 // any number of 0s on either side. The 1s are allowed to wrap from LSB to
1577 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
1578 // not, since all 1s are not contiguous.
1579 static bool isRunOfOnes(ConstantIntegral *Val, unsigned &MB, unsigned &ME) {
1580 uint64_t V = Val->getRawValue();
1581 if (!isShiftedMask_64(V)) return false;
1583 // look for the first zero bit after the run of ones
1584 MB = 64-CountLeadingZeros_64((V - 1) ^ V);
1585 // look for the first non-zero bit
1586 ME = 64-CountLeadingZeros_64(V);
1592 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
1593 /// where isSub determines whether the operator is a sub. If we can fold one of
1594 /// the following xforms:
1596 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
1597 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
1598 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
1600 /// return (A +/- B).
1602 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
1603 ConstantIntegral *Mask, bool isSub,
1605 Instruction *LHSI = dyn_cast<Instruction>(LHS);
1606 if (!LHSI || LHSI->getNumOperands() != 2 ||
1607 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
1609 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
1611 switch (LHSI->getOpcode()) {
1613 case Instruction::And:
1614 if (ConstantExpr::getAnd(N, Mask) == Mask) {
1615 // If the AndRHS is a power of two minus one (0+1+), this is simple.
1616 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0)
1619 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
1620 // part, we don't need any explicit masks to take them out of A. If that
1621 // is all N is, ignore it.
1623 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
1624 Constant *Mask = ConstantInt::getAllOnesValue(RHS->getType());
1625 Mask = ConstantExpr::getUShr(Mask,
1626 ConstantInt::get(Type::UByteTy,
1628 if (MaskedValueIsZero(RHS, cast<ConstantIntegral>(Mask)))
1633 case Instruction::Or:
1634 case Instruction::Xor:
1635 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
1636 if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0 &&
1637 ConstantExpr::getAnd(N, Mask)->isNullValue())
1644 New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold");
1646 New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold");
1647 return InsertNewInstBefore(New, I);
1651 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1652 bool Changed = SimplifyCommutative(I);
1653 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1655 if (isa<UndefValue>(Op1)) // X & undef -> 0
1656 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1660 return ReplaceInstUsesWith(I, Op1);
1662 if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) {
1664 if (AndRHS->isAllOnesValue())
1665 return ReplaceInstUsesWith(I, Op0);
1667 if (MaskedValueIsZero(Op0, AndRHS)) // LHS & RHS == 0
1668 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1670 // If the mask is not masking out any bits, there is no reason to do the
1671 // and in the first place.
1672 ConstantIntegral *NotAndRHS =
1673 cast<ConstantIntegral>(ConstantExpr::getNot(AndRHS));
1674 if (MaskedValueIsZero(Op0, NotAndRHS))
1675 return ReplaceInstUsesWith(I, Op0);
1677 // Optimize a variety of ((val OP C1) & C2) combinations...
1678 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
1679 Instruction *Op0I = cast<Instruction>(Op0);
1680 Value *Op0LHS = Op0I->getOperand(0);
1681 Value *Op0RHS = Op0I->getOperand(1);
1682 switch (Op0I->getOpcode()) {
1683 case Instruction::Xor:
1684 case Instruction::Or:
1685 // (X ^ V) & C2 --> (X & C2) iff (V & C2) == 0
1686 // (X | V) & C2 --> (X & C2) iff (V & C2) == 0
1687 if (MaskedValueIsZero(Op0LHS, AndRHS))
1688 return BinaryOperator::createAnd(Op0RHS, AndRHS);
1689 if (MaskedValueIsZero(Op0RHS, AndRHS))
1690 return BinaryOperator::createAnd(Op0LHS, AndRHS);
1692 // If the mask is only needed on one incoming arm, push it up.
1693 if (Op0I->hasOneUse()) {
1694 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
1695 // Not masking anything out for the LHS, move to RHS.
1696 Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
1697 Op0RHS->getName()+".masked");
1698 InsertNewInstBefore(NewRHS, I);
1699 return BinaryOperator::create(
1700 cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
1702 if (!isa<Constant>(NotAndRHS) &&
1703 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
1704 // Not masking anything out for the RHS, move to LHS.
1705 Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
1706 Op0LHS->getName()+".masked");
1707 InsertNewInstBefore(NewLHS, I);
1708 return BinaryOperator::create(
1709 cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
1714 case Instruction::And:
1715 // (X & V) & C2 --> 0 iff (V & C2) == 0
1716 if (MaskedValueIsZero(Op0LHS, AndRHS) ||
1717 MaskedValueIsZero(Op0RHS, AndRHS))
1718 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1720 case Instruction::Add:
1721 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
1722 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1723 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1724 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
1725 return BinaryOperator::createAnd(V, AndRHS);
1726 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
1727 return BinaryOperator::createAnd(V, AndRHS); // Add commutes
1730 case Instruction::Sub:
1731 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
1732 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1733 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1734 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
1735 return BinaryOperator::createAnd(V, AndRHS);
1739 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1740 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
1742 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
1743 const Type *SrcTy = CI->getOperand(0)->getType();
1745 // If this is an integer truncation or change from signed-to-unsigned, and
1746 // if the source is an and/or with immediate, transform it. This
1747 // frequently occurs for bitfield accesses.
1748 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
1749 if (SrcTy->getPrimitiveSizeInBits() >=
1750 I.getType()->getPrimitiveSizeInBits() &&
1751 CastOp->getNumOperands() == 2)
1752 if (ConstantInt *AndCI =dyn_cast<ConstantInt>(CastOp->getOperand(1)))
1753 if (CastOp->getOpcode() == Instruction::And) {
1754 // Change: and (cast (and X, C1) to T), C2
1755 // into : and (cast X to T), trunc(C1)&C2
1756 // This will folds the two ands together, which may allow other
1758 Instruction *NewCast =
1759 new CastInst(CastOp->getOperand(0), I.getType(),
1760 CastOp->getName()+".shrunk");
1761 NewCast = InsertNewInstBefore(NewCast, I);
1763 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1764 C3 = ConstantExpr::getAnd(C3, AndRHS); // trunc(C1)&C2
1765 return BinaryOperator::createAnd(NewCast, C3);
1766 } else if (CastOp->getOpcode() == Instruction::Or) {
1767 // Change: and (cast (or X, C1) to T), C2
1768 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
1769 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1770 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
1771 return ReplaceInstUsesWith(I, AndRHS);
1776 // If this is an integer sign or zero extension instruction.
1777 if (SrcTy->isIntegral() &&
1778 SrcTy->getPrimitiveSizeInBits() <
1779 CI->getType()->getPrimitiveSizeInBits()) {
1781 if (SrcTy->isUnsigned()) {
1782 // See if this and is clearing out bits that are known to be zero
1783 // anyway (due to the zero extension).
1784 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1785 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1786 Constant *Result = ConstantExpr::getAnd(Mask, AndRHS);
1787 if (Result == Mask) // The "and" isn't doing anything, remove it.
1788 return ReplaceInstUsesWith(I, CI);
1789 if (Result != AndRHS) { // Reduce the and RHS constant.
1790 I.setOperand(1, Result);
1795 if (CI->hasOneUse() && SrcTy->isInteger()) {
1796 // We can only do this if all of the sign bits brought in are masked
1797 // out. Compute this by first getting 0000011111, then inverting
1799 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1800 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1801 Mask = ConstantExpr::getNot(Mask); // 1's in the new bits.
1802 if (ConstantExpr::getAnd(Mask, AndRHS)->isNullValue()) {
1803 // If the and is clearing all of the sign bits, change this to a
1804 // zero extension cast. To do this, cast the cast input to
1805 // unsigned, then to the requested size.
1806 Value *CastOp = CI->getOperand(0);
1808 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
1809 CI->getName()+".uns");
1810 NC = InsertNewInstBefore(NC, I);
1811 // Finally, insert a replacement for CI.
1812 NC = new CastInst(NC, CI->getType(), CI->getName());
1814 NC = InsertNewInstBefore(NC, I);
1815 WorkList.push_back(CI); // Delete CI later.
1816 I.setOperand(0, NC);
1817 return &I; // The AND operand was modified.
1824 // Try to fold constant and into select arguments.
1825 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1826 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1828 if (isa<PHINode>(Op0))
1829 if (Instruction *NV = FoldOpIntoPhi(I))
1833 Value *Op0NotVal = dyn_castNotVal(Op0);
1834 Value *Op1NotVal = dyn_castNotVal(Op1);
1836 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1837 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1839 // (~A & ~B) == (~(A | B)) - De Morgan's Law
1840 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1841 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
1842 I.getName()+".demorgan");
1843 InsertNewInstBefore(Or, I);
1844 return BinaryOperator::createNot(Or);
1847 if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
1848 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1849 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1852 Value *LHSVal, *RHSVal;
1853 ConstantInt *LHSCst, *RHSCst;
1854 Instruction::BinaryOps LHSCC, RHSCC;
1855 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1856 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1857 if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
1858 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1859 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1860 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1861 // Ensure that the larger constant is on the RHS.
1862 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1863 SetCondInst *LHS = cast<SetCondInst>(Op0);
1864 if (cast<ConstantBool>(Cmp)->getValue()) {
1865 std::swap(LHS, RHS);
1866 std::swap(LHSCst, RHSCst);
1867 std::swap(LHSCC, RHSCC);
1870 // At this point, we know we have have two setcc instructions
1871 // comparing a value against two constants and and'ing the result
1872 // together. Because of the above check, we know that we only have
1873 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1874 // FoldSetCCLogical check above), that the two constants are not
1876 assert(LHSCst != RHSCst && "Compares not folded above?");
1879 default: assert(0 && "Unknown integer condition code!");
1880 case Instruction::SetEQ:
1882 default: assert(0 && "Unknown integer condition code!");
1883 case Instruction::SetEQ: // (X == 13 & X == 15) -> false
1884 case Instruction::SetGT: // (X == 13 & X > 15) -> false
1885 return ReplaceInstUsesWith(I, ConstantBool::False);
1886 case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
1887 case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
1888 return ReplaceInstUsesWith(I, LHS);
1890 case Instruction::SetNE:
1892 default: assert(0 && "Unknown integer condition code!");
1893 case Instruction::SetLT:
1894 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
1895 return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
1896 break; // (X != 13 & X < 15) -> no change
1897 case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
1898 case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
1899 return ReplaceInstUsesWith(I, RHS);
1900 case Instruction::SetNE:
1901 if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
1902 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1903 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
1904 LHSVal->getName()+".off");
1905 InsertNewInstBefore(Add, I);
1906 const Type *UnsType = Add->getType()->getUnsignedVersion();
1907 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
1908 AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
1909 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1910 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1912 break; // (X != 13 & X != 15) -> no change
1915 case Instruction::SetLT:
1917 default: assert(0 && "Unknown integer condition code!");
1918 case Instruction::SetEQ: // (X < 13 & X == 15) -> false
1919 case Instruction::SetGT: // (X < 13 & X > 15) -> false
1920 return ReplaceInstUsesWith(I, ConstantBool::False);
1921 case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
1922 case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
1923 return ReplaceInstUsesWith(I, LHS);
1925 case Instruction::SetGT:
1927 default: assert(0 && "Unknown integer condition code!");
1928 case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
1929 return ReplaceInstUsesWith(I, LHS);
1930 case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
1931 return ReplaceInstUsesWith(I, RHS);
1932 case Instruction::SetNE:
1933 if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
1934 return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
1935 break; // (X > 13 & X != 15) -> no change
1936 case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
1937 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
1943 return Changed ? &I : 0;
1946 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
1947 bool Changed = SimplifyCommutative(I);
1948 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1950 if (isa<UndefValue>(Op1))
1951 return ReplaceInstUsesWith(I, // X | undef -> -1
1952 ConstantIntegral::getAllOnesValue(I.getType()));
1954 // or X, X = X or X, 0 == X
1955 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
1956 return ReplaceInstUsesWith(I, Op0);
1959 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1960 // If X is known to only contain bits that already exist in RHS, just
1961 // replace this instruction with RHS directly.
1962 if (MaskedValueIsZero(Op0,
1963 cast<ConstantIntegral>(ConstantExpr::getNot(RHS))))
1964 return ReplaceInstUsesWith(I, RHS);
1966 ConstantInt *C1; Value *X;
1967 // (X & C1) | C2 --> (X | C2) & (C1|C2)
1968 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1969 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0->getName());
1971 InsertNewInstBefore(Or, I);
1972 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
1975 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
1976 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1977 std::string Op0Name = Op0->getName(); Op0->setName("");
1978 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
1979 InsertNewInstBefore(Or, I);
1980 return BinaryOperator::createXor(Or,
1981 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
1984 // Try to fold constant and into select arguments.
1985 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1986 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1988 if (isa<PHINode>(Op0))
1989 if (Instruction *NV = FoldOpIntoPhi(I))
1993 Value *A, *B; ConstantInt *C1, *C2;
1995 if (match(Op0, m_And(m_Value(A), m_Value(B))))
1996 if (A == Op1 || B == Op1) // (A & ?) | A --> A
1997 return ReplaceInstUsesWith(I, Op1);
1998 if (match(Op1, m_And(m_Value(A), m_Value(B))))
1999 if (A == Op0 || B == Op0) // A | (A & ?) --> A
2000 return ReplaceInstUsesWith(I, Op0);
2002 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
2003 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2004 MaskedValueIsZero(Op1, C1)) {
2005 Instruction *NOr = BinaryOperator::createOr(A, Op1, Op0->getName());
2007 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2010 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
2011 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
2012 MaskedValueIsZero(Op0, C1)) {
2013 Instruction *NOr = BinaryOperator::createOr(A, Op0, Op1->getName());
2015 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
2018 // (A & C1)|(B & C2)
2019 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2020 match(Op1, m_And(m_Value(B), m_ConstantInt(C2)))) {
2022 if (A == B) // (A & C1)|(A & C2) == A & (C1|C2)
2023 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
2026 // If we have: ((V + N) & C1) | (V & C2)
2027 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
2028 // replace with V+N.
2029 if (C1 == ConstantExpr::getNot(C2)) {
2031 if ((C2->getRawValue() & (C2->getRawValue()+1)) == 0 && // C2 == 0+1+
2032 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
2033 // Add commutes, try both ways.
2034 if (V1 == B && MaskedValueIsZero(V2, C2))
2035 return ReplaceInstUsesWith(I, A);
2036 if (V2 == B && MaskedValueIsZero(V1, C2))
2037 return ReplaceInstUsesWith(I, A);
2039 // Or commutes, try both ways.
2040 if ((C1->getRawValue() & (C1->getRawValue()+1)) == 0 &&
2041 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
2042 // Add commutes, try both ways.
2043 if (V1 == A && MaskedValueIsZero(V2, C1))
2044 return ReplaceInstUsesWith(I, B);
2045 if (V2 == A && MaskedValueIsZero(V1, C1))
2046 return ReplaceInstUsesWith(I, B);
2051 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
2052 if (A == Op1) // ~A | A == -1
2053 return ReplaceInstUsesWith(I,
2054 ConstantIntegral::getAllOnesValue(I.getType()));
2058 // Note, A is still live here!
2059 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
2061 return ReplaceInstUsesWith(I,
2062 ConstantIntegral::getAllOnesValue(I.getType()));
2064 // (~A | ~B) == (~(A & B)) - De Morgan's Law
2065 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
2066 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
2067 I.getName()+".demorgan"), I);
2068 return BinaryOperator::createNot(And);
2072 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
2073 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
2074 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2077 Value *LHSVal, *RHSVal;
2078 ConstantInt *LHSCst, *RHSCst;
2079 Instruction::BinaryOps LHSCC, RHSCC;
2080 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
2081 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
2082 if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
2083 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
2084 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
2085 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
2086 // Ensure that the larger constant is on the RHS.
2087 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
2088 SetCondInst *LHS = cast<SetCondInst>(Op0);
2089 if (cast<ConstantBool>(Cmp)->getValue()) {
2090 std::swap(LHS, RHS);
2091 std::swap(LHSCst, RHSCst);
2092 std::swap(LHSCC, RHSCC);
2095 // At this point, we know we have have two setcc instructions
2096 // comparing a value against two constants and or'ing the result
2097 // together. Because of the above check, we know that we only have
2098 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
2099 // FoldSetCCLogical check above), that the two constants are not
2101 assert(LHSCst != RHSCst && "Compares not folded above?");
2104 default: assert(0 && "Unknown integer condition code!");
2105 case Instruction::SetEQ:
2107 default: assert(0 && "Unknown integer condition code!");
2108 case Instruction::SetEQ:
2109 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
2110 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2111 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
2112 LHSVal->getName()+".off");
2113 InsertNewInstBefore(Add, I);
2114 const Type *UnsType = Add->getType()->getUnsignedVersion();
2115 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
2116 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
2117 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2118 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
2120 break; // (X == 13 | X == 15) -> no change
2122 case Instruction::SetGT: // (X == 13 | X > 14) -> no change
2124 case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
2125 case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
2126 return ReplaceInstUsesWith(I, RHS);
2129 case Instruction::SetNE:
2131 default: assert(0 && "Unknown integer condition code!");
2132 case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
2133 case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
2134 return ReplaceInstUsesWith(I, LHS);
2135 case Instruction::SetNE: // (X != 13 | X != 15) -> true
2136 case Instruction::SetLT: // (X != 13 | X < 15) -> true
2137 return ReplaceInstUsesWith(I, ConstantBool::True);
2140 case Instruction::SetLT:
2142 default: assert(0 && "Unknown integer condition code!");
2143 case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
2145 case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
2146 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
2147 case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
2148 case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
2149 return ReplaceInstUsesWith(I, RHS);
2152 case Instruction::SetGT:
2154 default: assert(0 && "Unknown integer condition code!");
2155 case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
2156 case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
2157 return ReplaceInstUsesWith(I, LHS);
2158 case Instruction::SetNE: // (X > 13 | X != 15) -> true
2159 case Instruction::SetLT: // (X > 13 | X < 15) -> true
2160 return ReplaceInstUsesWith(I, ConstantBool::True);
2166 return Changed ? &I : 0;
2169 // XorSelf - Implements: X ^ X --> 0
2172 XorSelf(Value *rhs) : RHS(rhs) {}
2173 bool shouldApply(Value *LHS) const { return LHS == RHS; }
2174 Instruction *apply(BinaryOperator &Xor) const {
2180 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
2181 bool Changed = SimplifyCommutative(I);
2182 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2184 if (isa<UndefValue>(Op1))
2185 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
2187 // xor X, X = 0, even if X is nested in a sequence of Xor's.
2188 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
2189 assert(Result == &I && "AssociativeOpt didn't work?");
2190 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2193 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2195 if (RHS->isNullValue())
2196 return ReplaceInstUsesWith(I, Op0);
2198 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2199 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
2200 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
2201 if (RHS == ConstantBool::True && SCI->hasOneUse())
2202 return new SetCondInst(SCI->getInverseCondition(),
2203 SCI->getOperand(0), SCI->getOperand(1));
2205 // ~(c-X) == X-c-1 == X+(-c-1)
2206 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
2207 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
2208 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
2209 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
2210 ConstantInt::get(I.getType(), 1));
2211 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
2214 // ~(~X & Y) --> (X | ~Y)
2215 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
2216 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
2217 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
2219 BinaryOperator::createNot(Op0I->getOperand(1),
2220 Op0I->getOperand(1)->getName()+".not");
2221 InsertNewInstBefore(NotY, I);
2222 return BinaryOperator::createOr(Op0NotVal, NotY);
2226 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
2227 switch (Op0I->getOpcode()) {
2228 case Instruction::Add:
2229 // ~(X-c) --> (-c-1)-X
2230 if (RHS->isAllOnesValue()) {
2231 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
2232 return BinaryOperator::createSub(
2233 ConstantExpr::getSub(NegOp0CI,
2234 ConstantInt::get(I.getType(), 1)),
2235 Op0I->getOperand(0));
2238 case Instruction::And:
2239 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
2240 if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue())
2241 return BinaryOperator::createOr(Op0, RHS);
2243 case Instruction::Or:
2244 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
2245 if (ConstantExpr::getAnd(RHS, Op0CI) == RHS)
2246 return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS));
2252 // Try to fold constant and into select arguments.
2253 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2254 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2256 if (isa<PHINode>(Op0))
2257 if (Instruction *NV = FoldOpIntoPhi(I))
2261 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
2263 return ReplaceInstUsesWith(I,
2264 ConstantIntegral::getAllOnesValue(I.getType()));
2266 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
2268 return ReplaceInstUsesWith(I,
2269 ConstantIntegral::getAllOnesValue(I.getType()));
2271 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
2272 if (Op1I->getOpcode() == Instruction::Or) {
2273 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
2274 cast<BinaryOperator>(Op1I)->swapOperands();
2276 std::swap(Op0, Op1);
2277 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
2279 std::swap(Op0, Op1);
2281 } else if (Op1I->getOpcode() == Instruction::Xor) {
2282 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
2283 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
2284 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
2285 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
2288 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
2289 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
2290 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
2291 cast<BinaryOperator>(Op0I)->swapOperands();
2292 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
2293 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
2294 Op1->getName()+".not"), I);
2295 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
2297 } else if (Op0I->getOpcode() == Instruction::Xor) {
2298 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
2299 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2300 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
2301 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2304 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
2305 Value *A, *B; ConstantInt *C1, *C2;
2306 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2307 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) &&
2308 ConstantExpr::getAnd(C1, C2)->isNullValue())
2309 return BinaryOperator::createOr(Op0, Op1);
2311 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
2312 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
2313 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2316 return Changed ? &I : 0;
2319 /// MulWithOverflow - Compute Result = In1*In2, returning true if the result
2320 /// overflowed for this type.
2321 static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2323 Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
2324 return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
2327 static bool isPositive(ConstantInt *C) {
2328 return cast<ConstantSInt>(C)->getValue() >= 0;
2331 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
2332 /// overflowed for this type.
2333 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2335 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
2337 if (In1->getType()->isUnsigned())
2338 return cast<ConstantUInt>(Result)->getValue() <
2339 cast<ConstantUInt>(In1)->getValue();
2340 if (isPositive(In1) != isPositive(In2))
2342 if (isPositive(In1))
2343 return cast<ConstantSInt>(Result)->getValue() <
2344 cast<ConstantSInt>(In1)->getValue();
2345 return cast<ConstantSInt>(Result)->getValue() >
2346 cast<ConstantSInt>(In1)->getValue();
2349 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
2350 /// code necessary to compute the offset from the base pointer (without adding
2351 /// in the base pointer). Return the result as a signed integer of intptr size.
2352 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
2353 TargetData &TD = IC.getTargetData();
2354 gep_type_iterator GTI = gep_type_begin(GEP);
2355 const Type *UIntPtrTy = TD.getIntPtrType();
2356 const Type *SIntPtrTy = UIntPtrTy->getSignedVersion();
2357 Value *Result = Constant::getNullValue(SIntPtrTy);
2359 // Build a mask for high order bits.
2360 uint64_t PtrSizeMask = ~0ULL;
2361 PtrSizeMask >>= 64-(TD.getPointerSize()*8);
2363 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
2364 Value *Op = GEP->getOperand(i);
2365 uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask;
2366 Constant *Scale = ConstantExpr::getCast(ConstantUInt::get(UIntPtrTy, Size),
2368 if (Constant *OpC = dyn_cast<Constant>(Op)) {
2369 if (!OpC->isNullValue()) {
2370 OpC = ConstantExpr::getCast(OpC, SIntPtrTy);
2371 Scale = ConstantExpr::getMul(OpC, Scale);
2372 if (Constant *RC = dyn_cast<Constant>(Result))
2373 Result = ConstantExpr::getAdd(RC, Scale);
2375 // Emit an add instruction.
2376 Result = IC.InsertNewInstBefore(
2377 BinaryOperator::createAdd(Result, Scale,
2378 GEP->getName()+".offs"), I);
2382 // Convert to correct type.
2383 Op = IC.InsertNewInstBefore(new CastInst(Op, SIntPtrTy,
2384 Op->getName()+".c"), I);
2386 // We'll let instcombine(mul) convert this to a shl if possible.
2387 Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
2388 GEP->getName()+".idx"), I);
2390 // Emit an add instruction.
2391 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
2392 GEP->getName()+".offs"), I);
2398 /// FoldGEPSetCC - Fold comparisons between a GEP instruction and something
2399 /// else. At this point we know that the GEP is on the LHS of the comparison.
2400 Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS,
2401 Instruction::BinaryOps Cond,
2403 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
2405 if (CastInst *CI = dyn_cast<CastInst>(RHS))
2406 if (isa<PointerType>(CI->getOperand(0)->getType()))
2407 RHS = CI->getOperand(0);
2409 Value *PtrBase = GEPLHS->getOperand(0);
2410 if (PtrBase == RHS) {
2411 // As an optimization, we don't actually have to compute the actual value of
2412 // OFFSET if this is a seteq or setne comparison, just return whether each
2413 // index is zero or not.
2414 if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) {
2415 Instruction *InVal = 0;
2416 gep_type_iterator GTI = gep_type_begin(GEPLHS);
2417 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
2419 if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
2420 if (isa<UndefValue>(C)) // undef index -> undef.
2421 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
2422 if (C->isNullValue())
2424 else if (TD->getTypeSize(GTI.getIndexedType()) == 0) {
2425 EmitIt = false; // This is indexing into a zero sized array?
2426 } else if (isa<ConstantInt>(C))
2427 return ReplaceInstUsesWith(I, // No comparison is needed here.
2428 ConstantBool::get(Cond == Instruction::SetNE));
2433 new SetCondInst(Cond, GEPLHS->getOperand(i),
2434 Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
2438 InVal = InsertNewInstBefore(InVal, I);
2439 InsertNewInstBefore(Comp, I);
2440 if (Cond == Instruction::SetNE) // True if any are unequal
2441 InVal = BinaryOperator::createOr(InVal, Comp);
2442 else // True if all are equal
2443 InVal = BinaryOperator::createAnd(InVal, Comp);
2451 ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0
2452 ConstantBool::get(Cond == Instruction::SetEQ));
2455 // Only lower this if the setcc is the only user of the GEP or if we expect
2456 // the result to fold to a constant!
2457 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
2458 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
2459 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
2460 return new SetCondInst(Cond, Offset,
2461 Constant::getNullValue(Offset->getType()));
2463 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
2464 // If the base pointers are different, but the indices are the same, just
2465 // compare the base pointer.
2466 if (PtrBase != GEPRHS->getOperand(0)) {
2467 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
2468 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
2469 GEPRHS->getOperand(0)->getType();
2471 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2472 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2473 IndicesTheSame = false;
2477 // If all indices are the same, just compare the base pointers.
2479 return new SetCondInst(Cond, GEPLHS->getOperand(0),
2480 GEPRHS->getOperand(0));
2482 // Otherwise, the base pointers are different and the indices are
2483 // different, bail out.
2487 // If one of the GEPs has all zero indices, recurse.
2488 bool AllZeros = true;
2489 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2490 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
2491 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
2496 return FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0),
2497 SetCondInst::getSwappedCondition(Cond), I);
2499 // If the other GEP has all zero indices, recurse.
2501 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2502 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
2503 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
2508 return FoldGEPSetCC(GEPLHS, GEPRHS->getOperand(0), Cond, I);
2510 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
2511 // If the GEPs only differ by one index, compare it.
2512 unsigned NumDifferences = 0; // Keep track of # differences.
2513 unsigned DiffOperand = 0; // The operand that differs.
2514 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2515 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2516 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
2517 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
2518 // Irreconcilable differences.
2522 if (NumDifferences++) break;
2527 if (NumDifferences == 0) // SAME GEP?
2528 return ReplaceInstUsesWith(I, // No comparison is needed here.
2529 ConstantBool::get(Cond == Instruction::SetEQ));
2530 else if (NumDifferences == 1) {
2531 Value *LHSV = GEPLHS->getOperand(DiffOperand);
2532 Value *RHSV = GEPRHS->getOperand(DiffOperand);
2534 // Convert the operands to signed values to make sure to perform a
2535 // signed comparison.
2536 const Type *NewTy = LHSV->getType()->getSignedVersion();
2537 if (LHSV->getType() != NewTy)
2538 LHSV = InsertNewInstBefore(new CastInst(LHSV, NewTy,
2539 LHSV->getName()), I);
2540 if (RHSV->getType() != NewTy)
2541 RHSV = InsertNewInstBefore(new CastInst(RHSV, NewTy,
2542 RHSV->getName()), I);
2543 return new SetCondInst(Cond, LHSV, RHSV);
2547 // Only lower this if the setcc is the only user of the GEP or if we expect
2548 // the result to fold to a constant!
2549 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
2550 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
2551 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
2552 Value *L = EmitGEPOffset(GEPLHS, I, *this);
2553 Value *R = EmitGEPOffset(GEPRHS, I, *this);
2554 return new SetCondInst(Cond, L, R);
2561 Instruction *InstCombiner::visitSetCondInst(SetCondInst &I) {
2562 bool Changed = SimplifyCommutative(I);
2563 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2564 const Type *Ty = Op0->getType();
2568 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
2570 if (isa<UndefValue>(Op1)) // X setcc undef -> undef
2571 return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
2573 // setcc <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
2574 // addresses never equal each other! We already know that Op0 != Op1.
2575 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
2576 isa<ConstantPointerNull>(Op0)) &&
2577 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
2578 isa<ConstantPointerNull>(Op1)))
2579 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
2581 // setcc's with boolean values can always be turned into bitwise operations
2582 if (Ty == Type::BoolTy) {
2583 switch (I.getOpcode()) {
2584 default: assert(0 && "Invalid setcc instruction!");
2585 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
2586 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
2587 InsertNewInstBefore(Xor, I);
2588 return BinaryOperator::createNot(Xor);
2590 case Instruction::SetNE:
2591 return BinaryOperator::createXor(Op0, Op1);
2593 case Instruction::SetGT:
2594 std::swap(Op0, Op1); // Change setgt -> setlt
2596 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
2597 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2598 InsertNewInstBefore(Not, I);
2599 return BinaryOperator::createAnd(Not, Op1);
2601 case Instruction::SetGE:
2602 std::swap(Op0, Op1); // Change setge -> setle
2604 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
2605 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2606 InsertNewInstBefore(Not, I);
2607 return BinaryOperator::createOr(Not, Op1);
2612 // See if we are doing a comparison between a constant and an instruction that
2613 // can be folded into the comparison.
2614 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2615 // Check to see if we are comparing against the minimum or maximum value...
2616 if (CI->isMinValue()) {
2617 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
2618 return ReplaceInstUsesWith(I, ConstantBool::False);
2619 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
2620 return ReplaceInstUsesWith(I, ConstantBool::True);
2621 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
2622 return BinaryOperator::createSetEQ(Op0, Op1);
2623 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
2624 return BinaryOperator::createSetNE(Op0, Op1);
2626 } else if (CI->isMaxValue()) {
2627 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
2628 return ReplaceInstUsesWith(I, ConstantBool::False);
2629 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
2630 return ReplaceInstUsesWith(I, ConstantBool::True);
2631 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
2632 return BinaryOperator::createSetEQ(Op0, Op1);
2633 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
2634 return BinaryOperator::createSetNE(Op0, Op1);
2636 // Comparing against a value really close to min or max?
2637 } else if (isMinValuePlusOne(CI)) {
2638 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
2639 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
2640 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
2641 return BinaryOperator::createSetNE(Op0, SubOne(CI));
2643 } else if (isMaxValueMinusOne(CI)) {
2644 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
2645 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
2646 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
2647 return BinaryOperator::createSetNE(Op0, AddOne(CI));
2650 // If we still have a setle or setge instruction, turn it into the
2651 // appropriate setlt or setgt instruction. Since the border cases have
2652 // already been handled above, this requires little checking.
2654 if (I.getOpcode() == Instruction::SetLE)
2655 return BinaryOperator::createSetLT(Op0, AddOne(CI));
2656 if (I.getOpcode() == Instruction::SetGE)
2657 return BinaryOperator::createSetGT(Op0, SubOne(CI));
2659 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
2660 switch (LHSI->getOpcode()) {
2661 case Instruction::And:
2662 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
2663 LHSI->getOperand(0)->hasOneUse()) {
2664 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
2665 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
2666 // happens a LOT in code produced by the C front-end, for bitfield
2668 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
2669 ConstantUInt *ShAmt;
2670 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
2671 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
2672 const Type *Ty = LHSI->getType();
2674 // We can fold this as long as we can't shift unknown bits
2675 // into the mask. This can only happen with signed shift
2676 // rights, as they sign-extend.
2678 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
2679 Shift->getType()->isUnsigned();
2681 // To test for the bad case of the signed shr, see if any
2682 // of the bits shifted in could be tested after the mask.
2683 int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue();
2684 if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
2686 Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal);
2688 ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
2689 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
2695 if (Shift->getOpcode() == Instruction::Shl)
2696 NewCst = ConstantExpr::getUShr(CI, ShAmt);
2698 NewCst = ConstantExpr::getShl(CI, ShAmt);
2700 // Check to see if we are shifting out any of the bits being
2702 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
2703 // If we shifted bits out, the fold is not going to work out.
2704 // As a special case, check to see if this means that the
2705 // result is always true or false now.
2706 if (I.getOpcode() == Instruction::SetEQ)
2707 return ReplaceInstUsesWith(I, ConstantBool::False);
2708 if (I.getOpcode() == Instruction::SetNE)
2709 return ReplaceInstUsesWith(I, ConstantBool::True);
2711 I.setOperand(1, NewCst);
2712 Constant *NewAndCST;
2713 if (Shift->getOpcode() == Instruction::Shl)
2714 NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
2716 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
2717 LHSI->setOperand(1, NewAndCST);
2718 LHSI->setOperand(0, Shift->getOperand(0));
2719 WorkList.push_back(Shift); // Shift is dead.
2720 AddUsesToWorkList(I);
2728 case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
2729 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2730 switch (I.getOpcode()) {
2732 case Instruction::SetEQ:
2733 case Instruction::SetNE: {
2734 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2736 // Check that the shift amount is in range. If not, don't perform
2737 // undefined shifts. When the shift is visited it will be
2739 if (ShAmt->getValue() >= TypeBits)
2742 // If we are comparing against bits always shifted out, the
2743 // comparison cannot succeed.
2745 ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
2746 if (Comp != CI) {// Comparing against a bit that we know is zero.
2747 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2748 Constant *Cst = ConstantBool::get(IsSetNE);
2749 return ReplaceInstUsesWith(I, Cst);
2752 if (LHSI->hasOneUse()) {
2753 // Otherwise strength reduce the shift into an and.
2754 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2755 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
2758 if (CI->getType()->isUnsigned()) {
2759 Mask = ConstantUInt::get(CI->getType(), Val);
2760 } else if (ShAmtVal != 0) {
2761 Mask = ConstantSInt::get(CI->getType(), Val);
2763 Mask = ConstantInt::getAllOnesValue(CI->getType());
2767 BinaryOperator::createAnd(LHSI->getOperand(0),
2768 Mask, LHSI->getName()+".mask");
2769 Value *And = InsertNewInstBefore(AndI, I);
2770 return new SetCondInst(I.getOpcode(), And,
2771 ConstantExpr::getUShr(CI, ShAmt));
2778 case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
2779 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2780 switch (I.getOpcode()) {
2782 case Instruction::SetEQ:
2783 case Instruction::SetNE: {
2785 // Check that the shift amount is in range. If not, don't perform
2786 // undefined shifts. When the shift is visited it will be
2788 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2789 if (ShAmt->getValue() >= TypeBits)
2792 // If we are comparing against bits always shifted out, the
2793 // comparison cannot succeed.
2795 ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
2797 if (Comp != CI) {// Comparing against a bit that we know is zero.
2798 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2799 Constant *Cst = ConstantBool::get(IsSetNE);
2800 return ReplaceInstUsesWith(I, Cst);
2803 if (LHSI->hasOneUse() || CI->isNullValue()) {
2804 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2806 // Otherwise strength reduce the shift into an and.
2807 uint64_t Val = ~0ULL; // All ones.
2808 Val <<= ShAmtVal; // Shift over to the right spot.
2811 if (CI->getType()->isUnsigned()) {
2812 Val &= ~0ULL >> (64-TypeBits);
2813 Mask = ConstantUInt::get(CI->getType(), Val);
2815 Mask = ConstantSInt::get(CI->getType(), Val);
2819 BinaryOperator::createAnd(LHSI->getOperand(0),
2820 Mask, LHSI->getName()+".mask");
2821 Value *And = InsertNewInstBefore(AndI, I);
2822 return new SetCondInst(I.getOpcode(), And,
2823 ConstantExpr::getShl(CI, ShAmt));
2831 case Instruction::Div:
2832 // Fold: (div X, C1) op C2 -> range check
2833 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
2834 // Fold this div into the comparison, producing a range check.
2835 // Determine, based on the divide type, what the range is being
2836 // checked. If there is an overflow on the low or high side, remember
2837 // it, otherwise compute the range [low, hi) bounding the new value.
2838 bool LoOverflow = false, HiOverflow = 0;
2839 ConstantInt *LoBound = 0, *HiBound = 0;
2842 bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
2844 Instruction::BinaryOps Opcode = I.getOpcode();
2846 if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
2847 } else if (LHSI->getType()->isUnsigned()) { // udiv
2849 LoOverflow = ProdOV;
2850 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
2851 } else if (isPositive(DivRHS)) { // Divisor is > 0.
2852 if (CI->isNullValue()) { // (X / pos) op 0
2854 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
2856 } else if (isPositive(CI)) { // (X / pos) op pos
2858 LoOverflow = ProdOV;
2859 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
2860 } else { // (X / pos) op neg
2861 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
2862 LoOverflow = AddWithOverflow(LoBound, Prod,
2863 cast<ConstantInt>(DivRHSH));
2865 HiOverflow = ProdOV;
2867 } else { // Divisor is < 0.
2868 if (CI->isNullValue()) { // (X / neg) op 0
2869 LoBound = AddOne(DivRHS);
2870 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
2871 if (HiBound == DivRHS)
2872 LoBound = 0; // - INTMIN = INTMIN
2873 } else if (isPositive(CI)) { // (X / neg) op pos
2874 HiOverflow = LoOverflow = ProdOV;
2876 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
2877 HiBound = AddOne(Prod);
2878 } else { // (X / neg) op neg
2880 LoOverflow = HiOverflow = ProdOV;
2881 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
2884 // Dividing by a negate swaps the condition.
2885 Opcode = SetCondInst::getSwappedCondition(Opcode);
2889 Value *X = LHSI->getOperand(0);
2891 default: assert(0 && "Unhandled setcc opcode!");
2892 case Instruction::SetEQ:
2893 if (LoOverflow && HiOverflow)
2894 return ReplaceInstUsesWith(I, ConstantBool::False);
2895 else if (HiOverflow)
2896 return new SetCondInst(Instruction::SetGE, X, LoBound);
2897 else if (LoOverflow)
2898 return new SetCondInst(Instruction::SetLT, X, HiBound);
2900 return InsertRangeTest(X, LoBound, HiBound, true, I);
2901 case Instruction::SetNE:
2902 if (LoOverflow && HiOverflow)
2903 return ReplaceInstUsesWith(I, ConstantBool::True);
2904 else if (HiOverflow)
2905 return new SetCondInst(Instruction::SetLT, X, LoBound);
2906 else if (LoOverflow)
2907 return new SetCondInst(Instruction::SetGE, X, HiBound);
2909 return InsertRangeTest(X, LoBound, HiBound, false, I);
2910 case Instruction::SetLT:
2912 return ReplaceInstUsesWith(I, ConstantBool::False);
2913 return new SetCondInst(Instruction::SetLT, X, LoBound);
2914 case Instruction::SetGT:
2916 return ReplaceInstUsesWith(I, ConstantBool::False);
2917 return new SetCondInst(Instruction::SetGE, X, HiBound);
2924 // Simplify seteq and setne instructions...
2925 if (I.getOpcode() == Instruction::SetEQ ||
2926 I.getOpcode() == Instruction::SetNE) {
2927 bool isSetNE = I.getOpcode() == Instruction::SetNE;
2929 // If the first operand is (and|or|xor) with a constant, and the second
2930 // operand is a constant, simplify a bit.
2931 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
2932 switch (BO->getOpcode()) {
2933 case Instruction::Rem:
2934 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
2935 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
2937 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1) {
2938 int64_t V = cast<ConstantSInt>(BO->getOperand(1))->getValue();
2939 if (isPowerOf2_64(V)) {
2940 unsigned L2 = Log2_64(V);
2941 const Type *UTy = BO->getType()->getUnsignedVersion();
2942 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
2944 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
2945 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
2946 RHSCst, BO->getName()), I);
2947 return BinaryOperator::create(I.getOpcode(), NewRem,
2948 Constant::getNullValue(UTy));
2953 case Instruction::Add:
2954 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
2955 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2956 if (BO->hasOneUse())
2957 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
2958 ConstantExpr::getSub(CI, BOp1C));
2959 } else if (CI->isNullValue()) {
2960 // Replace ((add A, B) != 0) with (A != -B) if A or B is
2961 // efficiently invertible, or if the add has just this one use.
2962 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
2964 if (Value *NegVal = dyn_castNegVal(BOp1))
2965 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
2966 else if (Value *NegVal = dyn_castNegVal(BOp0))
2967 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
2968 else if (BO->hasOneUse()) {
2969 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
2971 InsertNewInstBefore(Neg, I);
2972 return new SetCondInst(I.getOpcode(), BOp0, Neg);
2976 case Instruction::Xor:
2977 // For the xor case, we can xor two constants together, eliminating
2978 // the explicit xor.
2979 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
2980 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
2981 ConstantExpr::getXor(CI, BOC));
2984 case Instruction::Sub:
2985 // Replace (([sub|xor] A, B) != 0) with (A != B)
2986 if (CI->isNullValue())
2987 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
2991 case Instruction::Or:
2992 // If bits are being or'd in that are not present in the constant we
2993 // are comparing against, then the comparison could never succeed!
2994 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
2995 Constant *NotCI = ConstantExpr::getNot(CI);
2996 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
2997 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3001 case Instruction::And:
3002 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
3003 // If bits are being compared against that are and'd out, then the
3004 // comparison can never succeed!
3005 if (!ConstantExpr::getAnd(CI,
3006 ConstantExpr::getNot(BOC))->isNullValue())
3007 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
3009 // If we have ((X & C) == C), turn it into ((X & C) != 0).
3010 if (CI == BOC && isOneBitSet(CI))
3011 return new SetCondInst(isSetNE ? Instruction::SetEQ :
3012 Instruction::SetNE, Op0,
3013 Constant::getNullValue(CI->getType()));
3015 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
3016 // to be a signed value as appropriate.
3017 if (isSignBit(BOC)) {
3018 Value *X = BO->getOperand(0);
3019 // If 'X' is not signed, insert a cast now...
3020 if (!BOC->getType()->isSigned()) {
3021 const Type *DestTy = BOC->getType()->getSignedVersion();
3022 X = InsertCastBefore(X, DestTy, I);
3024 return new SetCondInst(isSetNE ? Instruction::SetLT :
3025 Instruction::SetGE, X,
3026 Constant::getNullValue(X->getType()));
3029 // ((X & ~7) == 0) --> X < 8
3030 if (CI->isNullValue() && isHighOnes(BOC)) {
3031 Value *X = BO->getOperand(0);
3032 Constant *NegX = ConstantExpr::getNeg(BOC);
3034 // If 'X' is signed, insert a cast now.
3035 if (NegX->getType()->isSigned()) {
3036 const Type *DestTy = NegX->getType()->getUnsignedVersion();
3037 X = InsertCastBefore(X, DestTy, I);
3038 NegX = ConstantExpr::getCast(NegX, DestTy);
3041 return new SetCondInst(isSetNE ? Instruction::SetGE :
3042 Instruction::SetLT, X, NegX);
3049 } else { // Not a SetEQ/SetNE
3050 // If the LHS is a cast from an integral value of the same size,
3051 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
3052 Value *CastOp = Cast->getOperand(0);
3053 const Type *SrcTy = CastOp->getType();
3054 unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits();
3055 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
3056 SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
3057 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
3058 "Source and destination signednesses should differ!");
3059 if (Cast->getType()->isSigned()) {
3060 // If this is a signed comparison, check for comparisons in the
3061 // vicinity of zero.
3062 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
3064 return BinaryOperator::createSetGT(CastOp,
3065 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize-1))-1));
3066 else if (I.getOpcode() == Instruction::SetGT &&
3067 cast<ConstantSInt>(CI)->getValue() == -1)
3068 // X > -1 => x < 128
3069 return BinaryOperator::createSetLT(CastOp,
3070 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize-1)));
3072 ConstantUInt *CUI = cast<ConstantUInt>(CI);
3073 if (I.getOpcode() == Instruction::SetLT &&
3074 CUI->getValue() == 1ULL << (SrcTySize-1))
3075 // X < 128 => X > -1
3076 return BinaryOperator::createSetGT(CastOp,
3077 ConstantSInt::get(SrcTy, -1));
3078 else if (I.getOpcode() == Instruction::SetGT &&
3079 CUI->getValue() == (1ULL << (SrcTySize-1))-1)
3081 return BinaryOperator::createSetLT(CastOp,
3082 Constant::getNullValue(SrcTy));
3089 // Handle setcc with constant RHS's that can be integer, FP or pointer.
3090 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
3091 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3092 switch (LHSI->getOpcode()) {
3093 case Instruction::GetElementPtr:
3094 if (RHSC->isNullValue()) {
3095 // Transform setcc GEP P, int 0, int 0, int 0, null -> setcc P, null
3096 bool isAllZeros = true;
3097 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
3098 if (!isa<Constant>(LHSI->getOperand(i)) ||
3099 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
3104 return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),
3105 Constant::getNullValue(LHSI->getOperand(0)->getType()));
3109 case Instruction::PHI:
3110 if (Instruction *NV = FoldOpIntoPhi(I))
3113 case Instruction::Select:
3114 // If either operand of the select is a constant, we can fold the
3115 // comparison into the select arms, which will cause one to be
3116 // constant folded and the select turned into a bitwise or.
3117 Value *Op1 = 0, *Op2 = 0;
3118 if (LHSI->hasOneUse()) {
3119 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
3120 // Fold the known value into the constant operand.
3121 Op1 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3122 // Insert a new SetCC of the other select operand.
3123 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3124 LHSI->getOperand(2), RHSC,
3126 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
3127 // Fold the known value into the constant operand.
3128 Op2 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3129 // Insert a new SetCC of the other select operand.
3130 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3131 LHSI->getOperand(1), RHSC,
3137 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
3142 // If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now.
3143 if (User *GEP = dyn_castGetElementPtr(Op0))
3144 if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I))
3146 if (User *GEP = dyn_castGetElementPtr(Op1))
3147 if (Instruction *NI = FoldGEPSetCC(GEP, Op0,
3148 SetCondInst::getSwappedCondition(I.getOpcode()), I))
3151 // Test to see if the operands of the setcc are casted versions of other
3152 // values. If the cast can be stripped off both arguments, we do so now.
3153 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3154 Value *CastOp0 = CI->getOperand(0);
3155 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
3156 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
3157 (I.getOpcode() == Instruction::SetEQ ||
3158 I.getOpcode() == Instruction::SetNE)) {
3159 // We keep moving the cast from the left operand over to the right
3160 // operand, where it can often be eliminated completely.
3163 // If operand #1 is a cast instruction, see if we can eliminate it as
3165 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
3166 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
3168 Op1 = CI2->getOperand(0);
3170 // If Op1 is a constant, we can fold the cast into the constant.
3171 if (Op1->getType() != Op0->getType())
3172 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
3173 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
3175 // Otherwise, cast the RHS right before the setcc
3176 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
3177 InsertNewInstBefore(cast<Instruction>(Op1), I);
3179 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
3182 // Handle the special case of: setcc (cast bool to X), <cst>
3183 // This comes up when you have code like
3186 // For generality, we handle any zero-extension of any operand comparison
3187 // with a constant or another cast from the same type.
3188 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
3189 if (Instruction *R = visitSetCondInstWithCastAndCast(I))
3192 return Changed ? &I : 0;
3195 // visitSetCondInstWithCastAndCast - Handle setcond (cast x to y), (cast/cst).
3196 // We only handle extending casts so far.
3198 Instruction *InstCombiner::visitSetCondInstWithCastAndCast(SetCondInst &SCI) {
3199 Value *LHSCIOp = cast<CastInst>(SCI.getOperand(0))->getOperand(0);
3200 const Type *SrcTy = LHSCIOp->getType();
3201 const Type *DestTy = SCI.getOperand(0)->getType();
3204 if (!DestTy->isIntegral() || !SrcTy->isIntegral())
3207 unsigned SrcBits = SrcTy->getPrimitiveSizeInBits();
3208 unsigned DestBits = DestTy->getPrimitiveSizeInBits();
3209 if (SrcBits >= DestBits) return 0; // Only handle extending cast.
3211 // Is this a sign or zero extension?
3212 bool isSignSrc = SrcTy->isSigned();
3213 bool isSignDest = DestTy->isSigned();
3215 if (CastInst *CI = dyn_cast<CastInst>(SCI.getOperand(1))) {
3216 // Not an extension from the same type?
3217 RHSCIOp = CI->getOperand(0);
3218 if (RHSCIOp->getType() != LHSCIOp->getType()) return 0;
3219 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(SCI.getOperand(1))) {
3220 // Compute the constant that would happen if we truncated to SrcTy then
3221 // reextended to DestTy.
3222 Constant *Res = ConstantExpr::getCast(CI, SrcTy);
3224 if (ConstantExpr::getCast(Res, DestTy) == CI) {
3227 // If the value cannot be represented in the shorter type, we cannot emit
3228 // a simple comparison.
3229 if (SCI.getOpcode() == Instruction::SetEQ)
3230 return ReplaceInstUsesWith(SCI, ConstantBool::False);
3231 if (SCI.getOpcode() == Instruction::SetNE)
3232 return ReplaceInstUsesWith(SCI, ConstantBool::True);
3234 // Evaluate the comparison for LT.
3236 if (DestTy->isSigned()) {
3237 // We're performing a signed comparison.
3239 // Signed extend and signed comparison.
3240 if (cast<ConstantSInt>(CI)->getValue() < 0) // X < (small) --> false
3241 Result = ConstantBool::False;
3243 Result = ConstantBool::True; // X < (large) --> true
3245 // Unsigned extend and signed comparison.
3246 if (cast<ConstantSInt>(CI)->getValue() < 0)
3247 Result = ConstantBool::False;
3249 Result = ConstantBool::True;
3252 // We're performing an unsigned comparison.
3254 // Unsigned extend & compare -> always true.
3255 Result = ConstantBool::True;
3257 // We're performing an unsigned comp with a sign extended value.
3258 // This is true if the input is >= 0. [aka >s -1]
3259 Constant *NegOne = ConstantIntegral::getAllOnesValue(SrcTy);
3260 Result = InsertNewInstBefore(BinaryOperator::createSetGT(LHSCIOp,
3261 NegOne, SCI.getName()), SCI);
3265 // Finally, return the value computed.
3266 if (SCI.getOpcode() == Instruction::SetLT) {
3267 return ReplaceInstUsesWith(SCI, Result);
3269 assert(SCI.getOpcode()==Instruction::SetGT &&"SetCC should be folded!");
3270 if (Constant *CI = dyn_cast<Constant>(Result))
3271 return ReplaceInstUsesWith(SCI, ConstantExpr::getNot(CI));
3273 return BinaryOperator::createNot(Result);
3280 // Okay, just insert a compare of the reduced operands now!
3281 return BinaryOperator::create(SCI.getOpcode(), LHSCIOp, RHSCIOp);
3284 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
3285 assert(I.getOperand(1)->getType() == Type::UByteTy);
3286 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3287 bool isLeftShift = I.getOpcode() == Instruction::Shl;
3289 // shl X, 0 == X and shr X, 0 == X
3290 // shl 0, X == 0 and shr 0, X == 0
3291 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
3292 Op0 == Constant::getNullValue(Op0->getType()))
3293 return ReplaceInstUsesWith(I, Op0);
3295 if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
3296 if (!isLeftShift && I.getType()->isSigned())
3297 return ReplaceInstUsesWith(I, Op0);
3298 else // undef << X -> 0 AND undef >>u X -> 0
3299 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3301 if (isa<UndefValue>(Op1)) {
3302 if (isLeftShift || I.getType()->isUnsigned())// X << undef, X >>u undef -> 0
3303 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3305 return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X
3308 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
3310 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
3311 if (CSI->isAllOnesValue())
3312 return ReplaceInstUsesWith(I, CSI);
3314 // Try to fold constant and into select arguments.
3315 if (isa<Constant>(Op0))
3316 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
3317 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3320 // See if we can turn a signed shr into an unsigned shr.
3321 if (!isLeftShift && I.getType()->isSigned()) {
3322 if (MaskedValueIsZero(Op0, ConstantInt::getMinValue(I.getType()))) {
3323 Value *V = InsertCastBefore(Op0, I.getType()->getUnsignedVersion(), I);
3324 V = InsertNewInstBefore(new ShiftInst(Instruction::Shr, V, Op1,
3326 return new CastInst(V, I.getType());
3330 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
3331 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
3332 // of a signed value.
3334 unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits();
3335 if (CUI->getValue() >= TypeBits) {
3336 if (!Op0->getType()->isSigned() || isLeftShift)
3337 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
3339 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
3344 // ((X*C1) << C2) == (X * (C1 << C2))
3345 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
3346 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
3347 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
3348 return BinaryOperator::createMul(BO->getOperand(0),
3349 ConstantExpr::getShl(BOOp, CUI));
3351 // Try to fold constant and into select arguments.
3352 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3353 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3355 if (isa<PHINode>(Op0))
3356 if (Instruction *NV = FoldOpIntoPhi(I))
3359 if (Op0->hasOneUse()) {
3360 // If this is a SHL of a sign-extending cast, see if we can turn the input
3361 // into a zero extending cast (a simple strength reduction).
3362 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3363 const Type *SrcTy = CI->getOperand(0)->getType();
3364 if (isLeftShift && SrcTy->isInteger() && SrcTy->isSigned() &&
3365 SrcTy->getPrimitiveSizeInBits() <
3366 CI->getType()->getPrimitiveSizeInBits()) {
3367 // We can change it to a zero extension if we are shifting out all of
3368 // the sign extended bits. To check this, form a mask of all of the
3369 // sign extend bits, then shift them left and see if we have anything
3371 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); // 1111
3372 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); // 00001111
3373 Mask = ConstantExpr::getNot(Mask); // 1's in the sign bits: 11110000
3374 if (ConstantExpr::getShl(Mask, CUI)->isNullValue()) {
3375 // If the shift is nuking all of the sign bits, change this to a
3376 // zero extension cast. To do this, cast the cast input to
3377 // unsigned, then to the requested size.
3378 Value *CastOp = CI->getOperand(0);
3380 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
3381 CI->getName()+".uns");
3382 NC = InsertNewInstBefore(NC, I);
3383 // Finally, insert a replacement for CI.
3384 NC = new CastInst(NC, CI->getType(), CI->getName());
3386 NC = InsertNewInstBefore(NC, I);
3387 WorkList.push_back(CI); // Delete CI later.
3388 I.setOperand(0, NC);
3389 return &I; // The SHL operand was modified.
3394 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
3395 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
3396 Value *V1, *V2, *V3;
3398 switch (Op0BO->getOpcode()) {
3400 case Instruction::Add:
3401 case Instruction::And:
3402 case Instruction::Or:
3403 case Instruction::Xor:
3404 // These operators commute.
3405 // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
3406 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
3407 match(Op0BO->getOperand(1),
3408 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == CUI) {
3409 Instruction *YS = new ShiftInst(Instruction::Shl,
3410 Op0BO->getOperand(0), CUI,
3412 InsertNewInstBefore(YS, I); // (Y << C)
3413 Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
3415 Op0BO->getOperand(1)->getName());
3416 InsertNewInstBefore(X, I); // (X + (Y << C))
3417 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
3418 C2 = ConstantExpr::getShl(C2, CUI);
3419 return BinaryOperator::createAnd(X, C2);
3422 // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
3423 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
3424 match(Op0BO->getOperand(1),
3425 m_And(m_Shr(m_Value(V1), m_Value(V2)),
3426 m_ConstantInt(CC))) && V2 == CUI &&
3427 cast<BinaryOperator>(Op0BO->getOperand(1))->getOperand(0)->hasOneUse()) {
3428 Instruction *YS = new ShiftInst(Instruction::Shl,
3429 Op0BO->getOperand(0), CUI,
3431 InsertNewInstBefore(YS, I); // (Y << C)
3433 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, CUI),
3434 V1->getName()+".mask");
3435 InsertNewInstBefore(XM, I); // X & (CC << C)
3437 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
3441 case Instruction::Sub:
3442 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
3443 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
3444 match(Op0BO->getOperand(0),
3445 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == CUI) {
3446 Instruction *YS = new ShiftInst(Instruction::Shl,
3447 Op0BO->getOperand(1), CUI,
3449 InsertNewInstBefore(YS, I); // (Y << C)
3450 Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
3452 Op0BO->getOperand(0)->getName());
3453 InsertNewInstBefore(X, I); // (X + (Y << C))
3454 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
3455 C2 = ConstantExpr::getShl(C2, CUI);
3456 return BinaryOperator::createAnd(X, C2);
3459 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
3460 match(Op0BO->getOperand(0),
3461 m_And(m_Shr(m_Value(V1), m_Value(V2)),
3462 m_ConstantInt(CC))) && V2 == CUI &&
3463 cast<BinaryOperator>(Op0BO->getOperand(0))->getOperand(0)->hasOneUse()) {
3464 Instruction *YS = new ShiftInst(Instruction::Shl,
3465 Op0BO->getOperand(1), CUI,
3467 InsertNewInstBefore(YS, I); // (Y << C)
3469 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, CUI),
3470 V1->getName()+".mask");
3471 InsertNewInstBefore(XM, I); // X & (CC << C)
3473 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
3480 // If the operand is an bitwise operator with a constant RHS, and the
3481 // shift is the only use, we can pull it out of the shift.
3482 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
3483 bool isValid = true; // Valid only for And, Or, Xor
3484 bool highBitSet = false; // Transform if high bit of constant set?
3486 switch (Op0BO->getOpcode()) {
3487 default: isValid = false; break; // Do not perform transform!
3488 case Instruction::Add:
3489 isValid = isLeftShift;
3491 case Instruction::Or:
3492 case Instruction::Xor:
3495 case Instruction::And:
3500 // If this is a signed shift right, and the high bit is modified
3501 // by the logical operation, do not perform the transformation.
3502 // The highBitSet boolean indicates the value of the high bit of
3503 // the constant which would cause it to be modified for this
3506 if (isValid && !isLeftShift && !I.getType()->isUnsigned()) {
3507 uint64_t Val = Op0C->getRawValue();
3508 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
3512 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI);
3514 Instruction *NewShift =
3515 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI,
3518 InsertNewInstBefore(NewShift, I);
3520 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
3527 // If this is a shift of a shift, see if we can fold the two together...
3528 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
3529 if (ConstantUInt *ShiftAmt1C =
3530 dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) {
3531 unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getValue();
3532 unsigned ShiftAmt2 = (unsigned)CUI->getValue();
3534 // Check for (A << c1) << c2 and (A >> c1) >> c2
3535 if (I.getOpcode() == Op0SI->getOpcode()) {
3536 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
3537 if (Op0->getType()->getPrimitiveSizeInBits() < Amt)
3538 Amt = Op0->getType()->getPrimitiveSizeInBits();
3539 return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
3540 ConstantUInt::get(Type::UByteTy, Amt));
3543 // Check for (A << c1) >> c2 or visaversa. If we are dealing with
3544 // signed types, we can only support the (A >> c1) << c2 configuration,
3545 // because it can not turn an arbitrary bit of A into a sign bit.
3546 if (I.getType()->isUnsigned() || isLeftShift) {
3547 // Calculate bitmask for what gets shifted off the edge...
3548 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
3550 C = ConstantExpr::getShl(C, ShiftAmt1C);
3552 C = ConstantExpr::getShr(C, ShiftAmt1C);
3555 BinaryOperator::createAnd(Op0SI->getOperand(0), C,
3556 Op0SI->getOperand(0)->getName()+".mask");
3557 InsertNewInstBefore(Mask, I);
3559 // Figure out what flavor of shift we should use...
3560 if (ShiftAmt1 == ShiftAmt2)
3561 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
3562 else if (ShiftAmt1 < ShiftAmt2) {
3563 return new ShiftInst(I.getOpcode(), Mask,
3564 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
3566 return new ShiftInst(Op0SI->getOpcode(), Mask,
3567 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
3583 /// getCastType - In the future, we will split the cast instruction into these
3584 /// various types. Until then, we have to do the analysis here.
3585 static CastType getCastType(const Type *Src, const Type *Dest) {
3586 assert(Src->isIntegral() && Dest->isIntegral() &&
3587 "Only works on integral types!");
3588 unsigned SrcSize = Src->getPrimitiveSizeInBits();
3589 unsigned DestSize = Dest->getPrimitiveSizeInBits();
3591 if (SrcSize == DestSize) return Noop;
3592 if (SrcSize > DestSize) return Truncate;
3593 if (Src->isSigned()) return Signext;
3598 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
3601 static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
3602 const Type *DstTy, TargetData *TD) {
3604 // It is legal to eliminate the instruction if casting A->B->A if the sizes
3605 // are identical and the bits don't get reinterpreted (for example
3606 // int->float->int would not be allowed).
3607 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
3610 // If we are casting between pointer and integer types, treat pointers as
3611 // integers of the appropriate size for the code below.
3612 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
3613 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
3614 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
3616 // Allow free casting and conversion of sizes as long as the sign doesn't
3618 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
3619 CastType FirstCast = getCastType(SrcTy, MidTy);
3620 CastType SecondCast = getCastType(MidTy, DstTy);
3622 // Capture the effect of these two casts. If the result is a legal cast,
3623 // the CastType is stored here, otherwise a special code is used.
3624 static const unsigned CastResult[] = {
3625 // First cast is noop
3627 // First cast is a truncate
3628 1, 1, 4, 4, // trunc->extend is not safe to eliminate
3629 // First cast is a sign ext
3630 2, 5, 2, 4, // signext->zeroext never ok
3631 // First cast is a zero ext
3635 unsigned Result = CastResult[FirstCast*4+SecondCast];
3637 default: assert(0 && "Illegal table value!");
3642 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
3643 // truncates, we could eliminate more casts.
3644 return (unsigned)getCastType(SrcTy, DstTy) == Result;
3646 return false; // Not possible to eliminate this here.
3648 // Sign or zero extend followed by truncate is always ok if the result
3649 // is a truncate or noop.
3650 CastType ResultCast = getCastType(SrcTy, DstTy);
3651 if (ResultCast == Noop || ResultCast == Truncate)
3653 // Otherwise we are still growing the value, we are only safe if the
3654 // result will match the sign/zeroextendness of the result.
3655 return ResultCast == FirstCast;
3661 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
3662 if (V->getType() == Ty || isa<Constant>(V)) return false;
3663 if (const CastInst *CI = dyn_cast<CastInst>(V))
3664 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
3670 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
3671 /// InsertBefore instruction. This is specialized a bit to avoid inserting
3672 /// casts that are known to not do anything...
3674 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
3675 Instruction *InsertBefore) {
3676 if (V->getType() == DestTy) return V;
3677 if (Constant *C = dyn_cast<Constant>(V))
3678 return ConstantExpr::getCast(C, DestTy);
3680 CastInst *CI = new CastInst(V, DestTy, V->getName());
3681 InsertNewInstBefore(CI, *InsertBefore);
3685 // CastInst simplification
3687 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
3688 Value *Src = CI.getOperand(0);
3690 // If the user is casting a value to the same type, eliminate this cast
3692 if (CI.getType() == Src->getType())
3693 return ReplaceInstUsesWith(CI, Src);
3695 if (isa<UndefValue>(Src)) // cast undef -> undef
3696 return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
3698 // If casting the result of another cast instruction, try to eliminate this
3701 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
3702 Value *A = CSrc->getOperand(0);
3703 if (isEliminableCastOfCast(A->getType(), CSrc->getType(),
3704 CI.getType(), TD)) {
3705 // This instruction now refers directly to the cast's src operand. This
3706 // has a good chance of making CSrc dead.
3707 CI.setOperand(0, CSrc->getOperand(0));
3711 // If this is an A->B->A cast, and we are dealing with integral types, try
3712 // to convert this into a logical 'and' instruction.
3714 if (A->getType()->isInteger() &&
3715 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
3716 CSrc->getType()->isUnsigned() && // B->A cast must zero extend
3717 CSrc->getType()->getPrimitiveSizeInBits() <
3718 CI.getType()->getPrimitiveSizeInBits()&&
3719 A->getType()->getPrimitiveSizeInBits() ==
3720 CI.getType()->getPrimitiveSizeInBits()) {
3721 assert(CSrc->getType() != Type::ULongTy &&
3722 "Cannot have type bigger than ulong!");
3723 uint64_t AndValue = ~0ULL>>(64-CSrc->getType()->getPrimitiveSizeInBits());
3724 Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(),
3726 AndOp = ConstantExpr::getCast(AndOp, A->getType());
3727 Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
3728 if (And->getType() != CI.getType()) {
3729 And->setName(CSrc->getName()+".mask");
3730 InsertNewInstBefore(And, CI);
3731 And = new CastInst(And, CI.getType());
3737 // If this is a cast to bool, turn it into the appropriate setne instruction.
3738 if (CI.getType() == Type::BoolTy)
3739 return BinaryOperator::createSetNE(CI.getOperand(0),
3740 Constant::getNullValue(CI.getOperand(0)->getType()));
3742 // If casting the result of a getelementptr instruction with no offset, turn
3743 // this into a cast of the original pointer!
3745 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
3746 bool AllZeroOperands = true;
3747 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
3748 if (!isa<Constant>(GEP->getOperand(i)) ||
3749 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
3750 AllZeroOperands = false;
3753 if (AllZeroOperands) {
3754 CI.setOperand(0, GEP->getOperand(0));
3759 // If we are casting a malloc or alloca to a pointer to a type of the same
3760 // size, rewrite the allocation instruction to allocate the "right" type.
3762 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
3763 if (AI->hasOneUse() && !AI->isArrayAllocation())
3764 if (const PointerType *PTy = dyn_cast<PointerType>(CI.getType())) {
3765 // Get the type really allocated and the type casted to...
3766 const Type *AllocElTy = AI->getAllocatedType();
3767 const Type *CastElTy = PTy->getElementType();
3768 if (AllocElTy->isSized() && CastElTy->isSized()) {
3769 uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
3770 uint64_t CastElTySize = TD->getTypeSize(CastElTy);
3772 // If the allocation is for an even multiple of the cast type size
3773 if (CastElTySize && (AllocElTySize % CastElTySize == 0)) {
3774 Value *Amt = ConstantUInt::get(Type::UIntTy,
3775 AllocElTySize/CastElTySize);
3776 std::string Name = AI->getName(); AI->setName("");
3777 AllocationInst *New;
3778 if (isa<MallocInst>(AI))
3779 New = new MallocInst(CastElTy, Amt, Name);
3781 New = new AllocaInst(CastElTy, Amt, Name);
3782 InsertNewInstBefore(New, *AI);
3783 return ReplaceInstUsesWith(CI, New);
3788 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
3789 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
3791 if (isa<PHINode>(Src))
3792 if (Instruction *NV = FoldOpIntoPhi(CI))
3795 // If the source value is an instruction with only this use, we can attempt to
3796 // propagate the cast into the instruction. Also, only handle integral types
3798 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
3799 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
3800 CI.getType()->isInteger()) { // Don't mess with casts to bool here
3801 const Type *DestTy = CI.getType();
3802 unsigned SrcBitSize = Src->getType()->getPrimitiveSizeInBits();
3803 unsigned DestBitSize = DestTy->getPrimitiveSizeInBits();
3805 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
3806 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
3808 switch (SrcI->getOpcode()) {
3809 case Instruction::Add:
3810 case Instruction::Mul:
3811 case Instruction::And:
3812 case Instruction::Or:
3813 case Instruction::Xor:
3814 // If we are discarding information, or just changing the sign, rewrite.
3815 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
3816 // Don't insert two casts if they cannot be eliminated. We allow two
3817 // casts to be inserted if the sizes are the same. This could only be
3818 // converting signedness, which is a noop.
3819 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
3820 !ValueRequiresCast(Op0, DestTy, TD)) {
3821 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
3822 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
3823 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
3824 ->getOpcode(), Op0c, Op1c);
3828 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
3829 if (SrcBitSize == 1 && SrcI->getOpcode() == Instruction::Xor &&
3830 Op1 == ConstantBool::True &&
3831 (!Op0->hasOneUse() || !isa<SetCondInst>(Op0))) {
3832 Value *New = InsertOperandCastBefore(Op0, DestTy, &CI);
3833 return BinaryOperator::createXor(New,
3834 ConstantInt::get(CI.getType(), 1));
3837 case Instruction::Shl:
3838 // Allow changing the sign of the source operand. Do not allow changing
3839 // the size of the shift, UNLESS the shift amount is a constant. We
3840 // mush not change variable sized shifts to a smaller size, because it
3841 // is undefined to shift more bits out than exist in the value.
3842 if (DestBitSize == SrcBitSize ||
3843 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
3844 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
3845 return new ShiftInst(Instruction::Shl, Op0c, Op1);
3848 case Instruction::Shr:
3849 // If this is a signed shr, and if all bits shifted in are about to be
3850 // truncated off, turn it into an unsigned shr to allow greater
3852 if (DestBitSize < SrcBitSize && Src->getType()->isSigned() &&
3853 isa<ConstantInt>(Op1)) {
3854 unsigned ShiftAmt = cast<ConstantUInt>(Op1)->getValue();
3855 if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
3856 // Convert to unsigned.
3857 Value *N1 = InsertOperandCastBefore(Op0,
3858 Op0->getType()->getUnsignedVersion(), &CI);
3859 // Insert the new shift, which is now unsigned.
3860 N1 = InsertNewInstBefore(new ShiftInst(Instruction::Shr, N1,
3861 Op1, Src->getName()), CI);
3862 return new CastInst(N1, CI.getType());
3867 case Instruction::SetNE:
3868 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
3869 if (Op1C->getRawValue() == 0) {
3870 // If the input only has the low bit set, simplify directly.
3872 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
3873 // cast (X != 0) to int --> X if X&~1 == 0
3874 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
3875 if (CI.getType() == Op0->getType())
3876 return ReplaceInstUsesWith(CI, Op0);
3878 return new CastInst(Op0, CI.getType());
3881 // If the input is an and with a single bit, shift then simplify.
3882 ConstantInt *AndRHS;
3883 if (match(Op0, m_And(m_Value(), m_ConstantInt(AndRHS))))
3884 if (AndRHS->getRawValue() &&
3885 (AndRHS->getRawValue() & (AndRHS->getRawValue()-1)) == 0) {
3886 unsigned ShiftAmt = Log2_64(AndRHS->getRawValue());
3887 // Perform an unsigned shr by shiftamt. Convert input to
3888 // unsigned if it is signed.
3890 if (In->getType()->isSigned())
3891 In = InsertNewInstBefore(new CastInst(In,
3892 In->getType()->getUnsignedVersion(), In->getName()),CI);
3893 // Insert the shift to put the result in the low bit.
3894 In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In,
3895 ConstantInt::get(Type::UByteTy, ShiftAmt),
3896 In->getName()+".lobit"), CI);
3897 if (CI.getType() == In->getType())
3898 return ReplaceInstUsesWith(CI, In);
3900 return new CastInst(In, CI.getType());
3905 case Instruction::SetEQ:
3906 // We if we are just checking for a seteq of a single bit and casting it
3907 // to an integer. If so, shift the bit to the appropriate place then
3908 // cast to integer to avoid the comparison.
3909 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
3910 // Is Op1C a power of two or zero?
3911 if ((Op1C->getRawValue() & Op1C->getRawValue()-1) == 0) {
3912 // cast (X == 1) to int -> X iff X has only the low bit set.
3913 if (Op1C->getRawValue() == 1) {
3915 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
3916 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
3917 if (CI.getType() == Op0->getType())
3918 return ReplaceInstUsesWith(CI, Op0);
3920 return new CastInst(Op0, CI.getType());
3931 /// GetSelectFoldableOperands - We want to turn code that looks like this:
3933 /// %D = select %cond, %C, %A
3935 /// %C = select %cond, %B, 0
3938 /// Assuming that the specified instruction is an operand to the select, return
3939 /// a bitmask indicating which operands of this instruction are foldable if they
3940 /// equal the other incoming value of the select.
3942 static unsigned GetSelectFoldableOperands(Instruction *I) {
3943 switch (I->getOpcode()) {
3944 case Instruction::Add:
3945 case Instruction::Mul:
3946 case Instruction::And:
3947 case Instruction::Or:
3948 case Instruction::Xor:
3949 return 3; // Can fold through either operand.
3950 case Instruction::Sub: // Can only fold on the amount subtracted.
3951 case Instruction::Shl: // Can only fold on the shift amount.
3952 case Instruction::Shr:
3955 return 0; // Cannot fold
3959 /// GetSelectFoldableConstant - For the same transformation as the previous
3960 /// function, return the identity constant that goes into the select.
3961 static Constant *GetSelectFoldableConstant(Instruction *I) {
3962 switch (I->getOpcode()) {
3963 default: assert(0 && "This cannot happen!"); abort();
3964 case Instruction::Add:
3965 case Instruction::Sub:
3966 case Instruction::Or:
3967 case Instruction::Xor:
3968 return Constant::getNullValue(I->getType());
3969 case Instruction::Shl:
3970 case Instruction::Shr:
3971 return Constant::getNullValue(Type::UByteTy);
3972 case Instruction::And:
3973 return ConstantInt::getAllOnesValue(I->getType());
3974 case Instruction::Mul:
3975 return ConstantInt::get(I->getType(), 1);
3979 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
3980 /// have the same opcode and only one use each. Try to simplify this.
3981 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
3983 if (TI->getNumOperands() == 1) {
3984 // If this is a non-volatile load or a cast from the same type,
3986 if (TI->getOpcode() == Instruction::Cast) {
3987 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
3990 return 0; // unknown unary op.
3993 // Fold this by inserting a select from the input values.
3994 SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
3995 FI->getOperand(0), SI.getName()+".v");
3996 InsertNewInstBefore(NewSI, SI);
3997 return new CastInst(NewSI, TI->getType());
4000 // Only handle binary operators here.
4001 if (!isa<ShiftInst>(TI) && !isa<BinaryOperator>(TI))
4004 // Figure out if the operations have any operands in common.
4005 Value *MatchOp, *OtherOpT, *OtherOpF;
4007 if (TI->getOperand(0) == FI->getOperand(0)) {
4008 MatchOp = TI->getOperand(0);
4009 OtherOpT = TI->getOperand(1);
4010 OtherOpF = FI->getOperand(1);
4011 MatchIsOpZero = true;
4012 } else if (TI->getOperand(1) == FI->getOperand(1)) {
4013 MatchOp = TI->getOperand(1);
4014 OtherOpT = TI->getOperand(0);
4015 OtherOpF = FI->getOperand(0);
4016 MatchIsOpZero = false;
4017 } else if (!TI->isCommutative()) {
4019 } else if (TI->getOperand(0) == FI->getOperand(1)) {
4020 MatchOp = TI->getOperand(0);
4021 OtherOpT = TI->getOperand(1);
4022 OtherOpF = FI->getOperand(0);
4023 MatchIsOpZero = true;
4024 } else if (TI->getOperand(1) == FI->getOperand(0)) {
4025 MatchOp = TI->getOperand(1);
4026 OtherOpT = TI->getOperand(0);
4027 OtherOpF = FI->getOperand(1);
4028 MatchIsOpZero = true;
4033 // If we reach here, they do have operations in common.
4034 SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
4035 OtherOpF, SI.getName()+".v");
4036 InsertNewInstBefore(NewSI, SI);
4038 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
4040 return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
4042 return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
4045 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI);
4047 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp);
4051 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
4052 Value *CondVal = SI.getCondition();
4053 Value *TrueVal = SI.getTrueValue();
4054 Value *FalseVal = SI.getFalseValue();
4056 // select true, X, Y -> X
4057 // select false, X, Y -> Y
4058 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
4059 if (C == ConstantBool::True)
4060 return ReplaceInstUsesWith(SI, TrueVal);
4062 assert(C == ConstantBool::False);
4063 return ReplaceInstUsesWith(SI, FalseVal);
4066 // select C, X, X -> X
4067 if (TrueVal == FalseVal)
4068 return ReplaceInstUsesWith(SI, TrueVal);
4070 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
4071 return ReplaceInstUsesWith(SI, FalseVal);
4072 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
4073 return ReplaceInstUsesWith(SI, TrueVal);
4074 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
4075 if (isa<Constant>(TrueVal))
4076 return ReplaceInstUsesWith(SI, TrueVal);
4078 return ReplaceInstUsesWith(SI, FalseVal);
4081 if (SI.getType() == Type::BoolTy)
4082 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
4083 if (C == ConstantBool::True) {
4084 // Change: A = select B, true, C --> A = or B, C
4085 return BinaryOperator::createOr(CondVal, FalseVal);
4087 // Change: A = select B, false, C --> A = and !B, C
4089 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4090 "not."+CondVal->getName()), SI);
4091 return BinaryOperator::createAnd(NotCond, FalseVal);
4093 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
4094 if (C == ConstantBool::False) {
4095 // Change: A = select B, C, false --> A = and B, C
4096 return BinaryOperator::createAnd(CondVal, TrueVal);
4098 // Change: A = select B, C, true --> A = or !B, C
4100 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4101 "not."+CondVal->getName()), SI);
4102 return BinaryOperator::createOr(NotCond, TrueVal);
4106 // Selecting between two integer constants?
4107 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
4108 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
4109 // select C, 1, 0 -> cast C to int
4110 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
4111 return new CastInst(CondVal, SI.getType());
4112 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
4113 // select C, 0, 1 -> cast !C to int
4115 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4116 "not."+CondVal->getName()), SI);
4117 return new CastInst(NotCond, SI.getType());
4120 // If one of the constants is zero (we know they can't both be) and we
4121 // have a setcc instruction with zero, and we have an 'and' with the
4122 // non-constant value, eliminate this whole mess. This corresponds to
4123 // cases like this: ((X & 27) ? 27 : 0)
4124 if (TrueValC->isNullValue() || FalseValC->isNullValue())
4125 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
4126 if ((IC->getOpcode() == Instruction::SetEQ ||
4127 IC->getOpcode() == Instruction::SetNE) &&
4128 isa<ConstantInt>(IC->getOperand(1)) &&
4129 cast<Constant>(IC->getOperand(1))->isNullValue())
4130 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
4131 if (ICA->getOpcode() == Instruction::And &&
4132 isa<ConstantInt>(ICA->getOperand(1)) &&
4133 (ICA->getOperand(1) == TrueValC ||
4134 ICA->getOperand(1) == FalseValC) &&
4135 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
4136 // Okay, now we know that everything is set up, we just don't
4137 // know whether we have a setne or seteq and whether the true or
4138 // false val is the zero.
4139 bool ShouldNotVal = !TrueValC->isNullValue();
4140 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
4143 V = InsertNewInstBefore(BinaryOperator::create(
4144 Instruction::Xor, V, ICA->getOperand(1)), SI);
4145 return ReplaceInstUsesWith(SI, V);
4149 // See if we are selecting two values based on a comparison of the two values.
4150 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
4151 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
4152 // Transform (X == Y) ? X : Y -> Y
4153 if (SCI->getOpcode() == Instruction::SetEQ)
4154 return ReplaceInstUsesWith(SI, FalseVal);
4155 // Transform (X != Y) ? X : Y -> X
4156 if (SCI->getOpcode() == Instruction::SetNE)
4157 return ReplaceInstUsesWith(SI, TrueVal);
4158 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
4160 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
4161 // Transform (X == Y) ? Y : X -> X
4162 if (SCI->getOpcode() == Instruction::SetEQ)
4163 return ReplaceInstUsesWith(SI, FalseVal);
4164 // Transform (X != Y) ? Y : X -> Y
4165 if (SCI->getOpcode() == Instruction::SetNE)
4166 return ReplaceInstUsesWith(SI, TrueVal);
4167 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
4171 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
4172 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
4173 if (TI->hasOneUse() && FI->hasOneUse()) {
4174 bool isInverse = false;
4175 Instruction *AddOp = 0, *SubOp = 0;
4177 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
4178 if (TI->getOpcode() == FI->getOpcode())
4179 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
4182 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
4183 // even legal for FP.
4184 if (TI->getOpcode() == Instruction::Sub &&
4185 FI->getOpcode() == Instruction::Add) {
4186 AddOp = FI; SubOp = TI;
4187 } else if (FI->getOpcode() == Instruction::Sub &&
4188 TI->getOpcode() == Instruction::Add) {
4189 AddOp = TI; SubOp = FI;
4193 Value *OtherAddOp = 0;
4194 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
4195 OtherAddOp = AddOp->getOperand(1);
4196 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
4197 OtherAddOp = AddOp->getOperand(0);
4201 // So at this point we know we have:
4202 // select C, (add X, Y), (sub X, ?)
4203 // We can do the transform profitably if either 'Y' = '?' or '?' is
4205 if (SubOp->getOperand(1) == AddOp ||
4206 isa<Constant>(SubOp->getOperand(1))) {
4208 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
4209 NegVal = ConstantExpr::getNeg(C);
4211 NegVal = InsertNewInstBefore(
4212 BinaryOperator::createNeg(SubOp->getOperand(1)), SI);
4215 Value *NewTrueOp = OtherAddOp;
4216 Value *NewFalseOp = NegVal;
4218 std::swap(NewTrueOp, NewFalseOp);
4219 Instruction *NewSel =
4220 new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
4222 NewSel = InsertNewInstBefore(NewSel, SI);
4223 return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
4229 // See if we can fold the select into one of our operands.
4230 if (SI.getType()->isInteger()) {
4231 // See the comment above GetSelectFoldableOperands for a description of the
4232 // transformation we are doing here.
4233 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
4234 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
4235 !isa<Constant>(FalseVal))
4236 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
4237 unsigned OpToFold = 0;
4238 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
4240 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
4245 Constant *C = GetSelectFoldableConstant(TVI);
4246 std::string Name = TVI->getName(); TVI->setName("");
4247 Instruction *NewSel =
4248 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
4250 InsertNewInstBefore(NewSel, SI);
4251 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
4252 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
4253 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
4254 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
4256 assert(0 && "Unknown instruction!!");
4261 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
4262 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
4263 !isa<Constant>(TrueVal))
4264 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
4265 unsigned OpToFold = 0;
4266 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
4268 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
4273 Constant *C = GetSelectFoldableConstant(FVI);
4274 std::string Name = FVI->getName(); FVI->setName("");
4275 Instruction *NewSel =
4276 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
4278 InsertNewInstBefore(NewSel, SI);
4279 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
4280 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
4281 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
4282 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
4284 assert(0 && "Unknown instruction!!");
4290 if (BinaryOperator::isNot(CondVal)) {
4291 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
4292 SI.setOperand(1, FalseVal);
4293 SI.setOperand(2, TrueVal);
4301 // CallInst simplification
4303 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
4304 // Intrinsics cannot occur in an invoke, so handle them here instead of in
4306 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(&CI)) {
4307 bool Changed = false;
4309 // memmove/cpy/set of zero bytes is a noop.
4310 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
4311 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
4313 // FIXME: Increase alignment here.
4315 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
4316 if (CI->getRawValue() == 1) {
4317 // Replace the instruction with just byte operations. We would
4318 // transform other cases to loads/stores, but we don't know if
4319 // alignment is sufficient.
4323 // If we have a memmove and the source operation is a constant global,
4324 // then the source and dest pointers can't alias, so we can change this
4325 // into a call to memcpy.
4326 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI))
4327 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
4328 if (GVSrc->isConstant()) {
4329 Module *M = CI.getParent()->getParent()->getParent();
4330 Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
4331 CI.getCalledFunction()->getFunctionType());
4332 CI.setOperand(0, MemCpy);
4336 if (Changed) return &CI;
4337 } else if (DbgStopPointInst *SPI = dyn_cast<DbgStopPointInst>(&CI)) {
4338 // If this stoppoint is at the same source location as the previous
4339 // stoppoint in the chain, it is not needed.
4340 if (DbgStopPointInst *PrevSPI =
4341 dyn_cast<DbgStopPointInst>(SPI->getChain()))
4342 if (SPI->getLineNo() == PrevSPI->getLineNo() &&
4343 SPI->getColNo() == PrevSPI->getColNo()) {
4344 SPI->replaceAllUsesWith(PrevSPI);
4345 return EraseInstFromFunction(CI);
4349 return visitCallSite(&CI);
4352 // InvokeInst simplification
4354 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
4355 return visitCallSite(&II);
4358 // visitCallSite - Improvements for call and invoke instructions.
4360 Instruction *InstCombiner::visitCallSite(CallSite CS) {
4361 bool Changed = false;
4363 // If the callee is a constexpr cast of a function, attempt to move the cast
4364 // to the arguments of the call/invoke.
4365 if (transformConstExprCastCall(CS)) return 0;
4367 Value *Callee = CS.getCalledValue();
4369 if (Function *CalleeF = dyn_cast<Function>(Callee))
4370 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
4371 Instruction *OldCall = CS.getInstruction();
4372 // If the call and callee calling conventions don't match, this call must
4373 // be unreachable, as the call is undefined.
4374 new StoreInst(ConstantBool::True,
4375 UndefValue::get(PointerType::get(Type::BoolTy)), OldCall);
4376 if (!OldCall->use_empty())
4377 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
4378 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
4379 return EraseInstFromFunction(*OldCall);
4383 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
4384 // This instruction is not reachable, just remove it. We insert a store to
4385 // undef so that we know that this code is not reachable, despite the fact
4386 // that we can't modify the CFG here.
4387 new StoreInst(ConstantBool::True,
4388 UndefValue::get(PointerType::get(Type::BoolTy)),
4389 CS.getInstruction());
4391 if (!CS.getInstruction()->use_empty())
4392 CS.getInstruction()->
4393 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
4395 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
4396 // Don't break the CFG, insert a dummy cond branch.
4397 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
4398 ConstantBool::True, II);
4400 return EraseInstFromFunction(*CS.getInstruction());
4403 const PointerType *PTy = cast<PointerType>(Callee->getType());
4404 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
4405 if (FTy->isVarArg()) {
4406 // See if we can optimize any arguments passed through the varargs area of
4408 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
4409 E = CS.arg_end(); I != E; ++I)
4410 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
4411 // If this cast does not effect the value passed through the varargs
4412 // area, we can eliminate the use of the cast.
4413 Value *Op = CI->getOperand(0);
4414 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
4421 return Changed ? CS.getInstruction() : 0;
4424 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
4425 // attempt to move the cast to the arguments of the call/invoke.
4427 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
4428 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
4429 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
4430 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
4432 Function *Callee = cast<Function>(CE->getOperand(0));
4433 Instruction *Caller = CS.getInstruction();
4435 // Okay, this is a cast from a function to a different type. Unless doing so
4436 // would cause a type conversion of one of our arguments, change this call to
4437 // be a direct call with arguments casted to the appropriate types.
4439 const FunctionType *FT = Callee->getFunctionType();
4440 const Type *OldRetTy = Caller->getType();
4442 // Check to see if we are changing the return type...
4443 if (OldRetTy != FT->getReturnType()) {
4444 if (Callee->isExternal() &&
4445 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
4446 !Caller->use_empty())
4447 return false; // Cannot transform this return value...
4449 // If the callsite is an invoke instruction, and the return value is used by
4450 // a PHI node in a successor, we cannot change the return type of the call
4451 // because there is no place to put the cast instruction (without breaking
4452 // the critical edge). Bail out in this case.
4453 if (!Caller->use_empty())
4454 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
4455 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
4457 if (PHINode *PN = dyn_cast<PHINode>(*UI))
4458 if (PN->getParent() == II->getNormalDest() ||
4459 PN->getParent() == II->getUnwindDest())
4463 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
4464 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
4466 CallSite::arg_iterator AI = CS.arg_begin();
4467 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
4468 const Type *ParamTy = FT->getParamType(i);
4469 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
4470 if (Callee->isExternal() && !isConvertible) return false;
4473 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
4474 Callee->isExternal())
4475 return false; // Do not delete arguments unless we have a function body...
4477 // Okay, we decided that this is a safe thing to do: go ahead and start
4478 // inserting cast instructions as necessary...
4479 std::vector<Value*> Args;
4480 Args.reserve(NumActualArgs);
4482 AI = CS.arg_begin();
4483 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
4484 const Type *ParamTy = FT->getParamType(i);
4485 if ((*AI)->getType() == ParamTy) {
4486 Args.push_back(*AI);
4488 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
4493 // If the function takes more arguments than the call was taking, add them
4495 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
4496 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
4498 // If we are removing arguments to the function, emit an obnoxious warning...
4499 if (FT->getNumParams() < NumActualArgs)
4500 if (!FT->isVarArg()) {
4501 std::cerr << "WARNING: While resolving call to function '"
4502 << Callee->getName() << "' arguments were dropped!\n";
4504 // Add all of the arguments in their promoted form to the arg list...
4505 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
4506 const Type *PTy = getPromotedType((*AI)->getType());
4507 if (PTy != (*AI)->getType()) {
4508 // Must promote to pass through va_arg area!
4509 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
4510 InsertNewInstBefore(Cast, *Caller);
4511 Args.push_back(Cast);
4513 Args.push_back(*AI);
4518 if (FT->getReturnType() == Type::VoidTy)
4519 Caller->setName(""); // Void type should not have a name...
4522 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4523 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
4524 Args, Caller->getName(), Caller);
4525 cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
4527 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
4528 if (cast<CallInst>(Caller)->isTailCall())
4529 cast<CallInst>(NC)->setTailCall();
4530 cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
4533 // Insert a cast of the return type as necessary...
4535 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
4536 if (NV->getType() != Type::VoidTy) {
4537 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
4539 // If this is an invoke instruction, we should insert it after the first
4540 // non-phi, instruction in the normal successor block.
4541 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4542 BasicBlock::iterator I = II->getNormalDest()->begin();
4543 while (isa<PHINode>(I)) ++I;
4544 InsertNewInstBefore(NC, *I);
4546 // Otherwise, it's a call, just insert cast right after the call instr
4547 InsertNewInstBefore(NC, *Caller);
4549 AddUsersToWorkList(*Caller);
4551 NV = UndefValue::get(Caller->getType());
4555 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
4556 Caller->replaceAllUsesWith(NV);
4557 Caller->getParent()->getInstList().erase(Caller);
4558 removeFromWorkList(Caller);
4563 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
4564 // operator and they all are only used by the PHI, PHI together their
4565 // inputs, and do the operation once, to the result of the PHI.
4566 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
4567 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
4569 // Scan the instruction, looking for input operations that can be folded away.
4570 // If all input operands to the phi are the same instruction (e.g. a cast from
4571 // the same type or "+42") we can pull the operation through the PHI, reducing
4572 // code size and simplifying code.
4573 Constant *ConstantOp = 0;
4574 const Type *CastSrcTy = 0;
4575 if (isa<CastInst>(FirstInst)) {
4576 CastSrcTy = FirstInst->getOperand(0)->getType();
4577 } else if (isa<BinaryOperator>(FirstInst) || isa<ShiftInst>(FirstInst)) {
4578 // Can fold binop or shift if the RHS is a constant.
4579 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
4580 if (ConstantOp == 0) return 0;
4582 return 0; // Cannot fold this operation.
4585 // Check to see if all arguments are the same operation.
4586 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4587 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
4588 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
4589 if (!I->hasOneUse() || I->getOpcode() != FirstInst->getOpcode())
4592 if (I->getOperand(0)->getType() != CastSrcTy)
4593 return 0; // Cast operation must match.
4594 } else if (I->getOperand(1) != ConstantOp) {
4599 // Okay, they are all the same operation. Create a new PHI node of the
4600 // correct type, and PHI together all of the LHS's of the instructions.
4601 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
4602 PN.getName()+".in");
4603 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
4605 Value *InVal = FirstInst->getOperand(0);
4606 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
4608 // Add all operands to the new PHI.
4609 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4610 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
4611 if (NewInVal != InVal)
4613 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
4618 // The new PHI unions all of the same values together. This is really
4619 // common, so we handle it intelligently here for compile-time speed.
4623 InsertNewInstBefore(NewPN, PN);
4627 // Insert and return the new operation.
4628 if (isa<CastInst>(FirstInst))
4629 return new CastInst(PhiVal, PN.getType());
4630 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
4631 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
4633 return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(),
4634 PhiVal, ConstantOp);
4637 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
4639 static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &PotentiallyDeadPHIs) {
4640 if (PN->use_empty()) return true;
4641 if (!PN->hasOneUse()) return false;
4643 // Remember this node, and if we find the cycle, return.
4644 if (!PotentiallyDeadPHIs.insert(PN).second)
4647 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
4648 return DeadPHICycle(PU, PotentiallyDeadPHIs);
4653 // PHINode simplification
4655 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
4656 if (Value *V = PN.hasConstantValue())
4657 return ReplaceInstUsesWith(PN, V);
4659 // If the only user of this instruction is a cast instruction, and all of the
4660 // incoming values are constants, change this PHI to merge together the casted
4663 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
4664 if (CI->getType() != PN.getType()) { // noop casts will be folded
4665 bool AllConstant = true;
4666 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
4667 if (!isa<Constant>(PN.getIncomingValue(i))) {
4668 AllConstant = false;
4672 // Make a new PHI with all casted values.
4673 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
4674 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
4675 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
4676 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
4677 PN.getIncomingBlock(i));
4680 // Update the cast instruction.
4681 CI->setOperand(0, New);
4682 WorkList.push_back(CI); // revisit the cast instruction to fold.
4683 WorkList.push_back(New); // Make sure to revisit the new Phi
4684 return &PN; // PN is now dead!
4688 // If all PHI operands are the same operation, pull them through the PHI,
4689 // reducing code size.
4690 if (isa<Instruction>(PN.getIncomingValue(0)) &&
4691 PN.getIncomingValue(0)->hasOneUse())
4692 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
4695 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
4696 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
4697 // PHI)... break the cycle.
4699 if (PHINode *PU = dyn_cast<PHINode>(PN.use_back())) {
4700 std::set<PHINode*> PotentiallyDeadPHIs;
4701 PotentiallyDeadPHIs.insert(&PN);
4702 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
4703 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
4709 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
4710 Instruction *InsertPoint,
4712 unsigned PS = IC->getTargetData().getPointerSize();
4713 const Type *VTy = V->getType();
4714 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
4715 // We must insert a cast to ensure we sign-extend.
4716 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
4717 V->getName()), *InsertPoint);
4718 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
4723 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
4724 Value *PtrOp = GEP.getOperand(0);
4725 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
4726 // If so, eliminate the noop.
4727 if (GEP.getNumOperands() == 1)
4728 return ReplaceInstUsesWith(GEP, PtrOp);
4730 if (isa<UndefValue>(GEP.getOperand(0)))
4731 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
4733 bool HasZeroPointerIndex = false;
4734 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
4735 HasZeroPointerIndex = C->isNullValue();
4737 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
4738 return ReplaceInstUsesWith(GEP, PtrOp);
4740 // Eliminate unneeded casts for indices.
4741 bool MadeChange = false;
4742 gep_type_iterator GTI = gep_type_begin(GEP);
4743 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
4744 if (isa<SequentialType>(*GTI)) {
4745 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
4746 Value *Src = CI->getOperand(0);
4747 const Type *SrcTy = Src->getType();
4748 const Type *DestTy = CI->getType();
4749 if (Src->getType()->isInteger()) {
4750 if (SrcTy->getPrimitiveSizeInBits() ==
4751 DestTy->getPrimitiveSizeInBits()) {
4752 // We can always eliminate a cast from ulong or long to the other.
4753 // We can always eliminate a cast from uint to int or the other on
4754 // 32-bit pointer platforms.
4755 if (DestTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()){
4757 GEP.setOperand(i, Src);
4759 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
4760 SrcTy->getPrimitiveSize() == 4) {
4761 // We can always eliminate a cast from int to [u]long. We can
4762 // eliminate a cast from uint to [u]long iff the target is a 32-bit
4764 if (SrcTy->isSigned() ||
4765 SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
4767 GEP.setOperand(i, Src);
4772 // If we are using a wider index than needed for this platform, shrink it
4773 // to what we need. If the incoming value needs a cast instruction,
4774 // insert it. This explicit cast can make subsequent optimizations more
4776 Value *Op = GEP.getOperand(i);
4777 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
4778 if (Constant *C = dyn_cast<Constant>(Op)) {
4779 GEP.setOperand(i, ConstantExpr::getCast(C,
4780 TD->getIntPtrType()->getSignedVersion()));
4783 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
4784 Op->getName()), GEP);
4785 GEP.setOperand(i, Op);
4789 // If this is a constant idx, make sure to canonicalize it to be a signed
4790 // operand, otherwise CSE and other optimizations are pessimized.
4791 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
4792 GEP.setOperand(i, ConstantExpr::getCast(CUI,
4793 CUI->getType()->getSignedVersion()));
4797 if (MadeChange) return &GEP;
4799 // Combine Indices - If the source pointer to this getelementptr instruction
4800 // is a getelementptr instruction, combine the indices of the two
4801 // getelementptr instructions into a single instruction.
4803 std::vector<Value*> SrcGEPOperands;
4804 if (User *Src = dyn_castGetElementPtr(PtrOp))
4805 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
4807 if (!SrcGEPOperands.empty()) {
4808 // Note that if our source is a gep chain itself that we wait for that
4809 // chain to be resolved before we perform this transformation. This
4810 // avoids us creating a TON of code in some cases.
4812 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
4813 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
4814 return 0; // Wait until our source is folded to completion.
4816 std::vector<Value *> Indices;
4818 // Find out whether the last index in the source GEP is a sequential idx.
4819 bool EndsWithSequential = false;
4820 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
4821 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
4822 EndsWithSequential = !isa<StructType>(*I);
4824 // Can we combine the two pointer arithmetics offsets?
4825 if (EndsWithSequential) {
4826 // Replace: gep (gep %P, long B), long A, ...
4827 // With: T = long A+B; gep %P, T, ...
4829 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
4830 if (SO1 == Constant::getNullValue(SO1->getType())) {
4832 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
4835 // If they aren't the same type, convert both to an integer of the
4836 // target's pointer size.
4837 if (SO1->getType() != GO1->getType()) {
4838 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
4839 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
4840 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
4841 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
4843 unsigned PS = TD->getPointerSize();
4844 if (SO1->getType()->getPrimitiveSize() == PS) {
4845 // Convert GO1 to SO1's type.
4846 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
4848 } else if (GO1->getType()->getPrimitiveSize() == PS) {
4849 // Convert SO1 to GO1's type.
4850 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
4852 const Type *PT = TD->getIntPtrType();
4853 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
4854 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
4858 if (isa<Constant>(SO1) && isa<Constant>(GO1))
4859 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
4861 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
4862 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
4866 // Recycle the GEP we already have if possible.
4867 if (SrcGEPOperands.size() == 2) {
4868 GEP.setOperand(0, SrcGEPOperands[0]);
4869 GEP.setOperand(1, Sum);
4872 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
4873 SrcGEPOperands.end()-1);
4874 Indices.push_back(Sum);
4875 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
4877 } else if (isa<Constant>(*GEP.idx_begin()) &&
4878 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
4879 SrcGEPOperands.size() != 1) {
4880 // Otherwise we can do the fold if the first index of the GEP is a zero
4881 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
4882 SrcGEPOperands.end());
4883 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
4886 if (!Indices.empty())
4887 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
4889 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
4890 // GEP of global variable. If all of the indices for this GEP are
4891 // constants, we can promote this to a constexpr instead of an instruction.
4893 // Scan for nonconstants...
4894 std::vector<Constant*> Indices;
4895 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
4896 for (; I != E && isa<Constant>(*I); ++I)
4897 Indices.push_back(cast<Constant>(*I));
4899 if (I == E) { // If they are all constants...
4900 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
4902 // Replace all uses of the GEP with the new constexpr...
4903 return ReplaceInstUsesWith(GEP, CE);
4905 } else if (Value *X = isCast(PtrOp)) { // Is the operand a cast?
4906 if (!isa<PointerType>(X->getType())) {
4907 // Not interesting. Source pointer must be a cast from pointer.
4908 } else if (HasZeroPointerIndex) {
4909 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
4910 // into : GEP [10 x ubyte]* X, long 0, ...
4912 // This occurs when the program declares an array extern like "int X[];"
4914 const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
4915 const PointerType *XTy = cast<PointerType>(X->getType());
4916 if (const ArrayType *XATy =
4917 dyn_cast<ArrayType>(XTy->getElementType()))
4918 if (const ArrayType *CATy =
4919 dyn_cast<ArrayType>(CPTy->getElementType()))
4920 if (CATy->getElementType() == XATy->getElementType()) {
4921 // At this point, we know that the cast source type is a pointer
4922 // to an array of the same type as the destination pointer
4923 // array. Because the array type is never stepped over (there
4924 // is a leading zero) we can fold the cast into this GEP.
4925 GEP.setOperand(0, X);
4928 } else if (GEP.getNumOperands() == 2) {
4929 // Transform things like:
4930 // %t = getelementptr ubyte* cast ([2 x int]* %str to uint*), uint %V
4931 // into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast
4932 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
4933 const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
4934 if (isa<ArrayType>(SrcElTy) &&
4935 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
4936 TD->getTypeSize(ResElTy)) {
4937 Value *V = InsertNewInstBefore(
4938 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
4939 GEP.getOperand(1), GEP.getName()), GEP);
4940 return new CastInst(V, GEP.getType());
4943 // Transform things like:
4944 // getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp
4945 // (where tmp = 8*tmp2) into:
4946 // getelementptr [100 x double]* %arr, int 0, int %tmp.2
4948 if (isa<ArrayType>(SrcElTy) &&
4949 (ResElTy == Type::SByteTy || ResElTy == Type::UByteTy)) {
4950 uint64_t ArrayEltSize =
4951 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType());
4953 // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
4954 // allow either a mul, shift, or constant here.
4956 ConstantInt *Scale = 0;
4957 if (ArrayEltSize == 1) {
4958 NewIdx = GEP.getOperand(1);
4959 Scale = ConstantInt::get(NewIdx->getType(), 1);
4960 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
4961 NewIdx = ConstantInt::get(CI->getType(), 1);
4963 } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
4964 if (Inst->getOpcode() == Instruction::Shl &&
4965 isa<ConstantInt>(Inst->getOperand(1))) {
4966 unsigned ShAmt =cast<ConstantUInt>(Inst->getOperand(1))->getValue();
4967 if (Inst->getType()->isSigned())
4968 Scale = ConstantSInt::get(Inst->getType(), 1ULL << ShAmt);
4970 Scale = ConstantUInt::get(Inst->getType(), 1ULL << ShAmt);
4971 NewIdx = Inst->getOperand(0);
4972 } else if (Inst->getOpcode() == Instruction::Mul &&
4973 isa<ConstantInt>(Inst->getOperand(1))) {
4974 Scale = cast<ConstantInt>(Inst->getOperand(1));
4975 NewIdx = Inst->getOperand(0);
4979 // If the index will be to exactly the right offset with the scale taken
4980 // out, perform the transformation.
4981 if (Scale && Scale->getRawValue() % ArrayEltSize == 0) {
4982 if (ConstantSInt *C = dyn_cast<ConstantSInt>(Scale))
4983 Scale = ConstantSInt::get(C->getType(),
4984 (int64_t)C->getRawValue() /
4985 (int64_t)ArrayEltSize);
4987 Scale = ConstantUInt::get(Scale->getType(),
4988 Scale->getRawValue() / ArrayEltSize);
4989 if (Scale->getRawValue() != 1) {
4990 Constant *C = ConstantExpr::getCast(Scale, NewIdx->getType());
4991 Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale");
4992 NewIdx = InsertNewInstBefore(Sc, GEP);
4995 // Insert the new GEP instruction.
4997 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
4998 NewIdx, GEP.getName());
4999 Idx = InsertNewInstBefore(Idx, GEP);
5000 return new CastInst(Idx, GEP.getType());
5009 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
5010 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
5011 if (AI.isArrayAllocation()) // Check C != 1
5012 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
5013 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
5014 AllocationInst *New = 0;
5016 // Create and insert the replacement instruction...
5017 if (isa<MallocInst>(AI))
5018 New = new MallocInst(NewTy, 0, AI.getName());
5020 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
5021 New = new AllocaInst(NewTy, 0, AI.getName());
5024 InsertNewInstBefore(New, AI);
5026 // Scan to the end of the allocation instructions, to skip over a block of
5027 // allocas if possible...
5029 BasicBlock::iterator It = New;
5030 while (isa<AllocationInst>(*It)) ++It;
5032 // Now that I is pointing to the first non-allocation-inst in the block,
5033 // insert our getelementptr instruction...
5035 Value *NullIdx = Constant::getNullValue(Type::IntTy);
5036 Value *V = new GetElementPtrInst(New, NullIdx, NullIdx,
5037 New->getName()+".sub", It);
5039 // Now make everything use the getelementptr instead of the original
5041 return ReplaceInstUsesWith(AI, V);
5042 } else if (isa<UndefValue>(AI.getArraySize())) {
5043 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5046 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
5047 // Note that we only do this for alloca's, because malloc should allocate and
5048 // return a unique pointer, even for a zero byte allocation.
5049 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
5050 TD->getTypeSize(AI.getAllocatedType()) == 0)
5051 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5056 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
5057 Value *Op = FI.getOperand(0);
5059 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
5060 if (CastInst *CI = dyn_cast<CastInst>(Op))
5061 if (isa<PointerType>(CI->getOperand(0)->getType())) {
5062 FI.setOperand(0, CI->getOperand(0));
5066 // free undef -> unreachable.
5067 if (isa<UndefValue>(Op)) {
5068 // Insert a new store to null because we cannot modify the CFG here.
5069 new StoreInst(ConstantBool::True,
5070 UndefValue::get(PointerType::get(Type::BoolTy)), &FI);
5071 return EraseInstFromFunction(FI);
5074 // If we have 'free null' delete the instruction. This can happen in stl code
5075 // when lots of inlining happens.
5076 if (isa<ConstantPointerNull>(Op))
5077 return EraseInstFromFunction(FI);
5083 /// GetGEPGlobalInitializer - Given a constant, and a getelementptr
5084 /// constantexpr, return the constant value being addressed by the constant
5085 /// expression, or null if something is funny.
5087 static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
5088 if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
5089 return 0; // Do not allow stepping over the value!
5091 // Loop over all of the operands, tracking down which value we are
5093 gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
5094 for (++I; I != E; ++I)
5095 if (const StructType *STy = dyn_cast<StructType>(*I)) {
5096 ConstantUInt *CU = cast<ConstantUInt>(I.getOperand());
5097 assert(CU->getValue() < STy->getNumElements() &&
5098 "Struct index out of range!");
5099 unsigned El = (unsigned)CU->getValue();
5100 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
5101 C = CS->getOperand(El);
5102 } else if (isa<ConstantAggregateZero>(C)) {
5103 C = Constant::getNullValue(STy->getElementType(El));
5104 } else if (isa<UndefValue>(C)) {
5105 C = UndefValue::get(STy->getElementType(El));
5109 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
5110 const ArrayType *ATy = cast<ArrayType>(*I);
5111 if ((uint64_t)CI->getRawValue() >= ATy->getNumElements()) return 0;
5112 if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
5113 C = CA->getOperand((unsigned)CI->getRawValue());
5114 else if (isa<ConstantAggregateZero>(C))
5115 C = Constant::getNullValue(ATy->getElementType());
5116 else if (isa<UndefValue>(C))
5117 C = UndefValue::get(ATy->getElementType());
5126 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
5127 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
5128 User *CI = cast<User>(LI.getOperand(0));
5129 Value *CastOp = CI->getOperand(0);
5131 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5132 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5133 const Type *SrcPTy = SrcTy->getElementType();
5135 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5136 // If the source is an array, the code below will not succeed. Check to
5137 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5139 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5140 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5141 if (ASrcTy->getNumElements() != 0) {
5142 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5143 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5144 SrcTy = cast<PointerType>(CastOp->getType());
5145 SrcPTy = SrcTy->getElementType();
5148 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5149 // Do not allow turning this into a load of an integer, which is then
5150 // casted to a pointer, this pessimizes pointer analysis a lot.
5151 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
5152 IC.getTargetData().getTypeSize(SrcPTy) ==
5153 IC.getTargetData().getTypeSize(DestPTy)) {
5155 // Okay, we are casting from one integer or pointer type to another of
5156 // the same size. Instead of casting the pointer before the load, cast
5157 // the result of the loaded value.
5158 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
5160 LI.isVolatile()),LI);
5161 // Now cast the result of the load.
5162 return new CastInst(NewLoad, LI.getType());
5169 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
5170 /// from this value cannot trap. If it is not obviously safe to load from the
5171 /// specified pointer, we do a quick local scan of the basic block containing
5172 /// ScanFrom, to determine if the address is already accessed.
5173 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
5174 // If it is an alloca or global variable, it is always safe to load from.
5175 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
5177 // Otherwise, be a little bit agressive by scanning the local block where we
5178 // want to check to see if the pointer is already being loaded or stored
5179 // from/to. If so, the previous load or store would have already trapped,
5180 // so there is no harm doing an extra load (also, CSE will later eliminate
5181 // the load entirely).
5182 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
5187 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
5188 if (LI->getOperand(0) == V) return true;
5189 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
5190 if (SI->getOperand(1) == V) return true;
5196 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
5197 Value *Op = LI.getOperand(0);
5199 // load (cast X) --> cast (load X) iff safe
5200 if (CastInst *CI = dyn_cast<CastInst>(Op))
5201 if (Instruction *Res = InstCombineLoadCast(*this, LI))
5204 // None of the following transforms are legal for volatile loads.
5205 if (LI.isVolatile()) return 0;
5207 if (&LI.getParent()->front() != &LI) {
5208 BasicBlock::iterator BBI = &LI; --BBI;
5209 // If the instruction immediately before this is a store to the same
5210 // address, do a simple form of store->load forwarding.
5211 if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
5212 if (SI->getOperand(1) == LI.getOperand(0))
5213 return ReplaceInstUsesWith(LI, SI->getOperand(0));
5214 if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
5215 if (LIB->getOperand(0) == LI.getOperand(0))
5216 return ReplaceInstUsesWith(LI, LIB);
5219 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
5220 if (isa<ConstantPointerNull>(GEPI->getOperand(0)) ||
5221 isa<UndefValue>(GEPI->getOperand(0))) {
5222 // Insert a new store to null instruction before the load to indicate
5223 // that this code is not reachable. We do this instead of inserting
5224 // an unreachable instruction directly because we cannot modify the
5226 new StoreInst(UndefValue::get(LI.getType()),
5227 Constant::getNullValue(Op->getType()), &LI);
5228 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5231 if (Constant *C = dyn_cast<Constant>(Op)) {
5232 // load null/undef -> undef
5233 if ((C->isNullValue() || isa<UndefValue>(C))) {
5234 // Insert a new store to null instruction before the load to indicate that
5235 // this code is not reachable. We do this instead of inserting an
5236 // unreachable instruction directly because we cannot modify the CFG.
5237 new StoreInst(UndefValue::get(LI.getType()),
5238 Constant::getNullValue(Op->getType()), &LI);
5239 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5242 // Instcombine load (constant global) into the value loaded.
5243 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
5244 if (GV->isConstant() && !GV->isExternal())
5245 return ReplaceInstUsesWith(LI, GV->getInitializer());
5247 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
5248 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
5249 if (CE->getOpcode() == Instruction::GetElementPtr) {
5250 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
5251 if (GV->isConstant() && !GV->isExternal())
5252 if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
5253 return ReplaceInstUsesWith(LI, V);
5254 if (CE->getOperand(0)->isNullValue()) {
5255 // Insert a new store to null instruction before the load to indicate
5256 // that this code is not reachable. We do this instead of inserting
5257 // an unreachable instruction directly because we cannot modify the
5259 new StoreInst(UndefValue::get(LI.getType()),
5260 Constant::getNullValue(Op->getType()), &LI);
5261 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5264 } else if (CE->getOpcode() == Instruction::Cast) {
5265 if (Instruction *Res = InstCombineLoadCast(*this, LI))
5270 if (Op->hasOneUse()) {
5271 // Change select and PHI nodes to select values instead of addresses: this
5272 // helps alias analysis out a lot, allows many others simplifications, and
5273 // exposes redundancy in the code.
5275 // Note that we cannot do the transformation unless we know that the
5276 // introduced loads cannot trap! Something like this is valid as long as
5277 // the condition is always false: load (select bool %C, int* null, int* %G),
5278 // but it would not be valid if we transformed it to load from null
5281 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
5282 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
5283 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
5284 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
5285 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
5286 SI->getOperand(1)->getName()+".val"), LI);
5287 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
5288 SI->getOperand(2)->getName()+".val"), LI);
5289 return new SelectInst(SI->getCondition(), V1, V2);
5292 // load (select (cond, null, P)) -> load P
5293 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
5294 if (C->isNullValue()) {
5295 LI.setOperand(0, SI->getOperand(2));
5299 // load (select (cond, P, null)) -> load P
5300 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
5301 if (C->isNullValue()) {
5302 LI.setOperand(0, SI->getOperand(1));
5306 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
5307 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
5308 bool Safe = PN->getParent() == LI.getParent();
5310 // Scan all of the instructions between the PHI and the load to make
5311 // sure there are no instructions that might possibly alter the value
5312 // loaded from the PHI.
5314 BasicBlock::iterator I = &LI;
5315 for (--I; !isa<PHINode>(I); --I)
5316 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
5322 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
5323 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
5324 PN->getIncomingBlock(i)->getTerminator()))
5329 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
5330 InsertNewInstBefore(NewPN, *PN);
5331 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
5333 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
5334 BasicBlock *BB = PN->getIncomingBlock(i);
5335 Value *&TheLoad = LoadMap[BB];
5337 Value *InVal = PN->getIncomingValue(i);
5338 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
5339 InVal->getName()+".val"),
5340 *BB->getTerminator());
5342 NewPN->addIncoming(TheLoad, BB);
5344 return ReplaceInstUsesWith(LI, NewPN);
5351 /// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store (cast V), P'
5353 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
5354 User *CI = cast<User>(SI.getOperand(1));
5355 Value *CastOp = CI->getOperand(0);
5357 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5358 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5359 const Type *SrcPTy = SrcTy->getElementType();
5361 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5362 // If the source is an array, the code below will not succeed. Check to
5363 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5365 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5366 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5367 if (ASrcTy->getNumElements() != 0) {
5368 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5369 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5370 SrcTy = cast<PointerType>(CastOp->getType());
5371 SrcPTy = SrcTy->getElementType();
5374 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5375 IC.getTargetData().getTypeSize(SrcPTy) ==
5376 IC.getTargetData().getTypeSize(DestPTy)) {
5378 // Okay, we are casting from one integer or pointer type to another of
5379 // the same size. Instead of casting the pointer before the store, cast
5380 // the value to be stored.
5382 if (Constant *C = dyn_cast<Constant>(SI.getOperand(0)))
5383 NewCast = ConstantExpr::getCast(C, SrcPTy);
5385 NewCast = IC.InsertNewInstBefore(new CastInst(SI.getOperand(0),
5387 SI.getOperand(0)->getName()+".c"), SI);
5389 return new StoreInst(NewCast, CastOp);
5396 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
5397 Value *Val = SI.getOperand(0);
5398 Value *Ptr = SI.getOperand(1);
5400 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
5401 removeFromWorkList(&SI);
5402 SI.eraseFromParent();
5407 if (SI.isVolatile()) return 0; // Don't hack volatile loads.
5409 // store X, null -> turns into 'unreachable' in SimplifyCFG
5410 if (isa<ConstantPointerNull>(Ptr)) {
5411 if (!isa<UndefValue>(Val)) {
5412 SI.setOperand(0, UndefValue::get(Val->getType()));
5413 if (Instruction *U = dyn_cast<Instruction>(Val))
5414 WorkList.push_back(U); // Dropped a use.
5417 return 0; // Do not modify these!
5420 // store undef, Ptr -> noop
5421 if (isa<UndefValue>(Val)) {
5422 removeFromWorkList(&SI);
5423 SI.eraseFromParent();
5428 // If the pointer destination is a cast, see if we can fold the cast into the
5430 if (CastInst *CI = dyn_cast<CastInst>(Ptr))
5431 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5433 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
5434 if (CE->getOpcode() == Instruction::Cast)
5435 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5439 // If this store is the last instruction in the basic block, and if the block
5440 // ends with an unconditional branch, try to move it to the successor block.
5441 BasicBlock::iterator BBI = &SI; ++BBI;
5442 if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
5443 if (BI->isUnconditional()) {
5444 // Check to see if the successor block has exactly two incoming edges. If
5445 // so, see if the other predecessor contains a store to the same location.
5446 // if so, insert a PHI node (if needed) and move the stores down.
5447 BasicBlock *Dest = BI->getSuccessor(0);
5449 pred_iterator PI = pred_begin(Dest);
5450 BasicBlock *Other = 0;
5451 if (*PI != BI->getParent())
5454 if (PI != pred_end(Dest)) {
5455 if (*PI != BI->getParent())
5460 if (++PI != pred_end(Dest))
5463 if (Other) { // If only one other pred...
5464 BBI = Other->getTerminator();
5465 // Make sure this other block ends in an unconditional branch and that
5466 // there is an instruction before the branch.
5467 if (isa<BranchInst>(BBI) && cast<BranchInst>(BBI)->isUnconditional() &&
5468 BBI != Other->begin()) {
5470 StoreInst *OtherStore = dyn_cast<StoreInst>(BBI);
5472 // If this instruction is a store to the same location.
5473 if (OtherStore && OtherStore->getOperand(1) == SI.getOperand(1)) {
5474 // Okay, we know we can perform this transformation. Insert a PHI
5475 // node now if we need it.
5476 Value *MergedVal = OtherStore->getOperand(0);
5477 if (MergedVal != SI.getOperand(0)) {
5478 PHINode *PN = new PHINode(MergedVal->getType(), "storemerge");
5479 PN->reserveOperandSpace(2);
5480 PN->addIncoming(SI.getOperand(0), SI.getParent());
5481 PN->addIncoming(OtherStore->getOperand(0), Other);
5482 MergedVal = InsertNewInstBefore(PN, Dest->front());
5485 // Advance to a place where it is safe to insert the new store and
5487 BBI = Dest->begin();
5488 while (isa<PHINode>(BBI)) ++BBI;
5489 InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
5490 OtherStore->isVolatile()), *BBI);
5492 // Nuke the old stores.
5493 removeFromWorkList(&SI);
5494 removeFromWorkList(OtherStore);
5495 SI.eraseFromParent();
5496 OtherStore->eraseFromParent();
5508 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
5509 // Change br (not X), label True, label False to: br X, label False, True
5511 BasicBlock *TrueDest;
5512 BasicBlock *FalseDest;
5513 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
5514 !isa<Constant>(X)) {
5515 // Swap Destinations and condition...
5517 BI.setSuccessor(0, FalseDest);
5518 BI.setSuccessor(1, TrueDest);
5522 // Cannonicalize setne -> seteq
5523 Instruction::BinaryOps Op; Value *Y;
5524 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
5525 TrueDest, FalseDest)))
5526 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
5527 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
5528 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
5529 std::string Name = I->getName(); I->setName("");
5530 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
5531 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
5532 // Swap Destinations and condition...
5533 BI.setCondition(NewSCC);
5534 BI.setSuccessor(0, FalseDest);
5535 BI.setSuccessor(1, TrueDest);
5536 removeFromWorkList(I);
5537 I->getParent()->getInstList().erase(I);
5538 WorkList.push_back(cast<Instruction>(NewSCC));
5545 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
5546 Value *Cond = SI.getCondition();
5547 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
5548 if (I->getOpcode() == Instruction::Add)
5549 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
5550 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
5551 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
5552 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
5554 SI.setOperand(0, I->getOperand(0));
5555 WorkList.push_back(I);
5563 void InstCombiner::removeFromWorkList(Instruction *I) {
5564 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
5569 /// TryToSinkInstruction - Try to move the specified instruction from its
5570 /// current block into the beginning of DestBlock, which can only happen if it's
5571 /// safe to move the instruction past all of the instructions between it and the
5572 /// end of its block.
5573 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
5574 assert(I->hasOneUse() && "Invariants didn't hold!");
5576 // Cannot move control-flow-involving instructions.
5577 if (isa<PHINode>(I) || isa<InvokeInst>(I) || isa<CallInst>(I)) return false;
5579 // Do not sink alloca instructions out of the entry block.
5580 if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front())
5583 // We can only sink load instructions if there is nothing between the load and
5584 // the end of block that could change the value.
5585 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
5586 if (LI->isVolatile()) return false; // Don't sink volatile loads.
5588 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
5590 if (Scan->mayWriteToMemory())
5594 BasicBlock::iterator InsertPos = DestBlock->begin();
5595 while (isa<PHINode>(InsertPos)) ++InsertPos;
5597 I->moveBefore(InsertPos);
5602 bool InstCombiner::runOnFunction(Function &F) {
5603 bool Changed = false;
5604 TD = &getAnalysis<TargetData>();
5607 // Populate the worklist with the reachable instructions.
5608 std::set<BasicBlock*> Visited;
5609 for (df_ext_iterator<BasicBlock*> BB = df_ext_begin(&F.front(), Visited),
5610 E = df_ext_end(&F.front(), Visited); BB != E; ++BB)
5611 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
5612 WorkList.push_back(I);
5614 // Do a quick scan over the function. If we find any blocks that are
5615 // unreachable, remove any instructions inside of them. This prevents
5616 // the instcombine code from having to deal with some bad special cases.
5617 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
5618 if (!Visited.count(BB)) {
5619 Instruction *Term = BB->getTerminator();
5620 while (Term != BB->begin()) { // Remove instrs bottom-up
5621 BasicBlock::iterator I = Term; --I;
5623 DEBUG(std::cerr << "IC: DCE: " << *I);
5626 if (!I->use_empty())
5627 I->replaceAllUsesWith(UndefValue::get(I->getType()));
5628 I->eraseFromParent();
5633 while (!WorkList.empty()) {
5634 Instruction *I = WorkList.back(); // Get an instruction from the worklist
5635 WorkList.pop_back();
5637 // Check to see if we can DCE or ConstantPropagate the instruction...
5638 // Check to see if we can DIE the instruction...
5639 if (isInstructionTriviallyDead(I)) {
5640 // Add operands to the worklist...
5641 if (I->getNumOperands() < 4)
5642 AddUsesToWorkList(*I);
5645 DEBUG(std::cerr << "IC: DCE: " << *I);
5647 I->eraseFromParent();
5648 removeFromWorkList(I);
5652 // Instruction isn't dead, see if we can constant propagate it...
5653 if (Constant *C = ConstantFoldInstruction(I)) {
5654 Value* Ptr = I->getOperand(0);
5655 if (isa<GetElementPtrInst>(I) &&
5656 cast<Constant>(Ptr)->isNullValue() &&
5657 !isa<ConstantPointerNull>(C) &&
5658 cast<PointerType>(Ptr->getType())->getElementType()->isSized()) {
5659 // If this is a constant expr gep that is effectively computing an
5660 // "offsetof", fold it into 'cast int X to T*' instead of 'gep 0, 0, 12'
5661 bool isFoldableGEP = true;
5662 for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
5663 if (!isa<ConstantInt>(I->getOperand(i)))
5664 isFoldableGEP = false;
5665 if (isFoldableGEP) {
5666 uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
5667 std::vector<Value*>(I->op_begin()+1, I->op_end()));
5668 C = ConstantUInt::get(Type::ULongTy, Offset);
5669 C = ConstantExpr::getCast(C, TD->getIntPtrType());
5670 C = ConstantExpr::getCast(C, I->getType());
5674 DEBUG(std::cerr << "IC: ConstFold to: " << *C << " from: " << *I);
5676 // Add operands to the worklist...
5677 AddUsesToWorkList(*I);
5678 ReplaceInstUsesWith(*I, C);
5681 I->getParent()->getInstList().erase(I);
5682 removeFromWorkList(I);
5686 // See if we can trivially sink this instruction to a successor basic block.
5687 if (I->hasOneUse()) {
5688 BasicBlock *BB = I->getParent();
5689 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
5690 if (UserParent != BB) {
5691 bool UserIsSuccessor = false;
5692 // See if the user is one of our successors.
5693 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
5694 if (*SI == UserParent) {
5695 UserIsSuccessor = true;
5699 // If the user is one of our immediate successors, and if that successor
5700 // only has us as a predecessors (we'd have to split the critical edge
5701 // otherwise), we can keep going.
5702 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
5703 next(pred_begin(UserParent)) == pred_end(UserParent))
5704 // Okay, the CFG is simple enough, try to sink this instruction.
5705 Changed |= TryToSinkInstruction(I, UserParent);
5709 // Now that we have an instruction, try combining it to simplify it...
5710 if (Instruction *Result = visit(*I)) {
5712 // Should we replace the old instruction with a new one?
5714 DEBUG(std::cerr << "IC: Old = " << *I
5715 << " New = " << *Result);
5717 // Everything uses the new instruction now.
5718 I->replaceAllUsesWith(Result);
5720 // Push the new instruction and any users onto the worklist.
5721 WorkList.push_back(Result);
5722 AddUsersToWorkList(*Result);
5724 // Move the name to the new instruction first...
5725 std::string OldName = I->getName(); I->setName("");
5726 Result->setName(OldName);
5728 // Insert the new instruction into the basic block...
5729 BasicBlock *InstParent = I->getParent();
5730 BasicBlock::iterator InsertPos = I;
5732 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
5733 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
5736 InstParent->getInstList().insert(InsertPos, Result);
5738 // Make sure that we reprocess all operands now that we reduced their
5740 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
5741 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
5742 WorkList.push_back(OpI);
5744 // Instructions can end up on the worklist more than once. Make sure
5745 // we do not process an instruction that has been deleted.
5746 removeFromWorkList(I);
5748 // Erase the old instruction.
5749 InstParent->getInstList().erase(I);
5751 DEBUG(std::cerr << "IC: MOD = " << *I);
5753 // If the instruction was modified, it's possible that it is now dead.
5754 // if so, remove it.
5755 if (isInstructionTriviallyDead(I)) {
5756 // Make sure we process all operands now that we are reducing their
5758 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
5759 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
5760 WorkList.push_back(OpI);
5762 // Instructions may end up in the worklist more than once. Erase all
5763 // occurrances of this instruction.
5764 removeFromWorkList(I);
5765 I->eraseFromParent();
5767 WorkList.push_back(Result);
5768 AddUsersToWorkList(*Result);
5778 FunctionPass *llvm::createInstructionCombiningPass() {
5779 return new InstCombiner();