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 /// FoldLogicalPlusAnd - We know that Mask is of the form 0+1+, and that this is
1576 /// part of an expression (LHS +/- RHS) & Mask, where isSub determines whether
1577 /// the operator is a sub. If we can fold one of the following xforms:
1579 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
1580 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
1581 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
1583 /// return (A +/- B).
1585 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
1586 ConstantIntegral *Mask, bool isSub,
1588 Instruction *LHSI = dyn_cast<Instruction>(LHS);
1589 if (!LHSI || LHSI->getNumOperands() != 2 ||
1590 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
1592 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
1594 switch (LHSI->getOpcode()) {
1596 case Instruction::And:
1597 if (ConstantExpr::getAnd(N, Mask) == Mask)
1600 case Instruction::Or:
1601 case Instruction::Xor:
1602 if (ConstantExpr::getAnd(N, Mask)->isNullValue())
1609 New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold");
1611 New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold");
1612 return InsertNewInstBefore(New, I);
1616 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1617 bool Changed = SimplifyCommutative(I);
1618 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1620 if (isa<UndefValue>(Op1)) // X & undef -> 0
1621 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1625 return ReplaceInstUsesWith(I, Op1);
1627 if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) {
1629 if (AndRHS->isAllOnesValue())
1630 return ReplaceInstUsesWith(I, Op0);
1632 if (MaskedValueIsZero(Op0, AndRHS)) // LHS & RHS == 0
1633 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1635 // If the mask is not masking out any bits, there is no reason to do the
1636 // and in the first place.
1637 ConstantIntegral *NotAndRHS =
1638 cast<ConstantIntegral>(ConstantExpr::getNot(AndRHS));
1639 if (MaskedValueIsZero(Op0, NotAndRHS))
1640 return ReplaceInstUsesWith(I, Op0);
1642 // Optimize a variety of ((val OP C1) & C2) combinations...
1643 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
1644 Instruction *Op0I = cast<Instruction>(Op0);
1645 Value *Op0LHS = Op0I->getOperand(0);
1646 Value *Op0RHS = Op0I->getOperand(1);
1647 switch (Op0I->getOpcode()) {
1648 case Instruction::Xor:
1649 case Instruction::Or:
1650 // (X ^ V) & C2 --> (X & C2) iff (V & C2) == 0
1651 // (X | V) & C2 --> (X & C2) iff (V & C2) == 0
1652 if (MaskedValueIsZero(Op0LHS, AndRHS))
1653 return BinaryOperator::createAnd(Op0RHS, AndRHS);
1654 if (MaskedValueIsZero(Op0RHS, AndRHS))
1655 return BinaryOperator::createAnd(Op0LHS, AndRHS);
1657 // If the mask is only needed on one incoming arm, push it up.
1658 if (Op0I->hasOneUse()) {
1659 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
1660 // Not masking anything out for the LHS, move to RHS.
1661 Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
1662 Op0RHS->getName()+".masked");
1663 InsertNewInstBefore(NewRHS, I);
1664 return BinaryOperator::create(
1665 cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
1667 if (!isa<Constant>(NotAndRHS) &&
1668 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
1669 // Not masking anything out for the RHS, move to LHS.
1670 Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
1671 Op0LHS->getName()+".masked");
1672 InsertNewInstBefore(NewLHS, I);
1673 return BinaryOperator::create(
1674 cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
1679 case Instruction::And:
1680 // (X & V) & C2 --> 0 iff (V & C2) == 0
1681 if (MaskedValueIsZero(Op0LHS, AndRHS) ||
1682 MaskedValueIsZero(Op0RHS, AndRHS))
1683 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1685 case Instruction::Add:
1686 // If the AndRHS is a power of two minus one (0+1+).
1687 if ((AndRHS->getRawValue() & AndRHS->getRawValue()+1) == 0) {
1688 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
1689 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1690 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1691 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
1692 return BinaryOperator::createAnd(V, AndRHS);
1693 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
1694 return BinaryOperator::createAnd(V, AndRHS); // Add commutes
1698 case Instruction::Sub:
1699 // If the AndRHS is a power of two minus one (0+1+).
1700 if ((AndRHS->getRawValue() & AndRHS->getRawValue()+1) == 0) {
1701 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
1702 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1703 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1704 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
1705 return BinaryOperator::createAnd(V, AndRHS);
1710 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1711 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
1713 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
1714 const Type *SrcTy = CI->getOperand(0)->getType();
1716 // If this is an integer truncation or change from signed-to-unsigned, and
1717 // if the source is an and/or with immediate, transform it. This
1718 // frequently occurs for bitfield accesses.
1719 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
1720 if (SrcTy->getPrimitiveSizeInBits() >=
1721 I.getType()->getPrimitiveSizeInBits() &&
1722 CastOp->getNumOperands() == 2)
1723 if (ConstantInt *AndCI =dyn_cast<ConstantInt>(CastOp->getOperand(1)))
1724 if (CastOp->getOpcode() == Instruction::And) {
1725 // Change: and (cast (and X, C1) to T), C2
1726 // into : and (cast X to T), trunc(C1)&C2
1727 // This will folds the two ands together, which may allow other
1729 Instruction *NewCast =
1730 new CastInst(CastOp->getOperand(0), I.getType(),
1731 CastOp->getName()+".shrunk");
1732 NewCast = InsertNewInstBefore(NewCast, I);
1734 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1735 C3 = ConstantExpr::getAnd(C3, AndRHS); // trunc(C1)&C2
1736 return BinaryOperator::createAnd(NewCast, C3);
1737 } else if (CastOp->getOpcode() == Instruction::Or) {
1738 // Change: and (cast (or X, C1) to T), C2
1739 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
1740 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1741 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
1742 return ReplaceInstUsesWith(I, AndRHS);
1747 // If this is an integer sign or zero extension instruction.
1748 if (SrcTy->isIntegral() &&
1749 SrcTy->getPrimitiveSizeInBits() <
1750 CI->getType()->getPrimitiveSizeInBits()) {
1752 if (SrcTy->isUnsigned()) {
1753 // See if this and is clearing out bits that are known to be zero
1754 // anyway (due to the zero extension).
1755 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1756 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1757 Constant *Result = ConstantExpr::getAnd(Mask, AndRHS);
1758 if (Result == Mask) // The "and" isn't doing anything, remove it.
1759 return ReplaceInstUsesWith(I, CI);
1760 if (Result != AndRHS) { // Reduce the and RHS constant.
1761 I.setOperand(1, Result);
1766 if (CI->hasOneUse() && SrcTy->isInteger()) {
1767 // We can only do this if all of the sign bits brought in are masked
1768 // out. Compute this by first getting 0000011111, then inverting
1770 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1771 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1772 Mask = ConstantExpr::getNot(Mask); // 1's in the new bits.
1773 if (ConstantExpr::getAnd(Mask, AndRHS)->isNullValue()) {
1774 // If the and is clearing all of the sign bits, change this to a
1775 // zero extension cast. To do this, cast the cast input to
1776 // unsigned, then to the requested size.
1777 Value *CastOp = CI->getOperand(0);
1779 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
1780 CI->getName()+".uns");
1781 NC = InsertNewInstBefore(NC, I);
1782 // Finally, insert a replacement for CI.
1783 NC = new CastInst(NC, CI->getType(), CI->getName());
1785 NC = InsertNewInstBefore(NC, I);
1786 WorkList.push_back(CI); // Delete CI later.
1787 I.setOperand(0, NC);
1788 return &I; // The AND operand was modified.
1795 // Try to fold constant and into select arguments.
1796 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1797 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1799 if (isa<PHINode>(Op0))
1800 if (Instruction *NV = FoldOpIntoPhi(I))
1804 Value *Op0NotVal = dyn_castNotVal(Op0);
1805 Value *Op1NotVal = dyn_castNotVal(Op1);
1807 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1808 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1810 // (~A & ~B) == (~(A | B)) - De Morgan's Law
1811 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1812 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
1813 I.getName()+".demorgan");
1814 InsertNewInstBefore(Or, I);
1815 return BinaryOperator::createNot(Or);
1818 if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
1819 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1820 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1823 Value *LHSVal, *RHSVal;
1824 ConstantInt *LHSCst, *RHSCst;
1825 Instruction::BinaryOps LHSCC, RHSCC;
1826 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1827 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1828 if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
1829 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1830 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1831 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1832 // Ensure that the larger constant is on the RHS.
1833 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1834 SetCondInst *LHS = cast<SetCondInst>(Op0);
1835 if (cast<ConstantBool>(Cmp)->getValue()) {
1836 std::swap(LHS, RHS);
1837 std::swap(LHSCst, RHSCst);
1838 std::swap(LHSCC, RHSCC);
1841 // At this point, we know we have have two setcc instructions
1842 // comparing a value against two constants and and'ing the result
1843 // together. Because of the above check, we know that we only have
1844 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1845 // FoldSetCCLogical check above), that the two constants are not
1847 assert(LHSCst != RHSCst && "Compares not folded above?");
1850 default: assert(0 && "Unknown integer condition code!");
1851 case Instruction::SetEQ:
1853 default: assert(0 && "Unknown integer condition code!");
1854 case Instruction::SetEQ: // (X == 13 & X == 15) -> false
1855 case Instruction::SetGT: // (X == 13 & X > 15) -> false
1856 return ReplaceInstUsesWith(I, ConstantBool::False);
1857 case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
1858 case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
1859 return ReplaceInstUsesWith(I, LHS);
1861 case Instruction::SetNE:
1863 default: assert(0 && "Unknown integer condition code!");
1864 case Instruction::SetLT:
1865 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
1866 return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
1867 break; // (X != 13 & X < 15) -> no change
1868 case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
1869 case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
1870 return ReplaceInstUsesWith(I, RHS);
1871 case Instruction::SetNE:
1872 if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
1873 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1874 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
1875 LHSVal->getName()+".off");
1876 InsertNewInstBefore(Add, I);
1877 const Type *UnsType = Add->getType()->getUnsignedVersion();
1878 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
1879 AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
1880 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1881 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1883 break; // (X != 13 & X != 15) -> no change
1886 case Instruction::SetLT:
1888 default: assert(0 && "Unknown integer condition code!");
1889 case Instruction::SetEQ: // (X < 13 & X == 15) -> false
1890 case Instruction::SetGT: // (X < 13 & X > 15) -> false
1891 return ReplaceInstUsesWith(I, ConstantBool::False);
1892 case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
1893 case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
1894 return ReplaceInstUsesWith(I, LHS);
1896 case Instruction::SetGT:
1898 default: assert(0 && "Unknown integer condition code!");
1899 case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
1900 return ReplaceInstUsesWith(I, LHS);
1901 case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
1902 return ReplaceInstUsesWith(I, RHS);
1903 case Instruction::SetNE:
1904 if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
1905 return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
1906 break; // (X > 13 & X != 15) -> no change
1907 case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
1908 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
1914 return Changed ? &I : 0;
1917 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
1918 bool Changed = SimplifyCommutative(I);
1919 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1921 if (isa<UndefValue>(Op1))
1922 return ReplaceInstUsesWith(I, // X | undef -> -1
1923 ConstantIntegral::getAllOnesValue(I.getType()));
1925 // or X, X = X or X, 0 == X
1926 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
1927 return ReplaceInstUsesWith(I, Op0);
1930 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1931 // If X is known to only contain bits that already exist in RHS, just
1932 // replace this instruction with RHS directly.
1933 if (MaskedValueIsZero(Op0,
1934 cast<ConstantIntegral>(ConstantExpr::getNot(RHS))))
1935 return ReplaceInstUsesWith(I, RHS);
1937 ConstantInt *C1; Value *X;
1938 // (X & C1) | C2 --> (X | C2) & (C1|C2)
1939 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1940 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0->getName());
1942 InsertNewInstBefore(Or, I);
1943 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
1946 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
1947 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1948 std::string Op0Name = Op0->getName(); Op0->setName("");
1949 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
1950 InsertNewInstBefore(Or, I);
1951 return BinaryOperator::createXor(Or,
1952 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
1955 // Try to fold constant and into select arguments.
1956 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1957 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1959 if (isa<PHINode>(Op0))
1960 if (Instruction *NV = FoldOpIntoPhi(I))
1964 Value *A, *B; ConstantInt *C1, *C2;
1966 if (match(Op0, m_And(m_Value(A), m_Value(B))))
1967 if (A == Op1 || B == Op1) // (A & ?) | A --> A
1968 return ReplaceInstUsesWith(I, Op1);
1969 if (match(Op1, m_And(m_Value(A), m_Value(B))))
1970 if (A == Op0 || B == Op0) // A | (A & ?) --> A
1971 return ReplaceInstUsesWith(I, Op0);
1973 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
1974 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
1975 MaskedValueIsZero(Op1, C1)) {
1976 Instruction *NOr = BinaryOperator::createOr(A, Op1, Op0->getName());
1978 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
1981 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
1982 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
1983 MaskedValueIsZero(Op0, C1)) {
1984 Instruction *NOr = BinaryOperator::createOr(A, Op0, Op1->getName());
1986 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
1989 // (A & C1)|(B & C2)
1990 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
1991 match(Op1, m_And(m_Value(B), m_ConstantInt(C2)))) {
1993 if (A == B) // (A & C1)|(A & C2) == A & (C1|C2)
1994 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
1997 // If we have: ((V + N) & C1) | (V & C2)
1998 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
1999 // replace with V+N.
2000 if (C1 == ConstantExpr::getNot(C2)) {
2002 if ((C2->getRawValue() & (C2->getRawValue()+1)) == 0 && // C2 == 0+1+
2003 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
2004 // Add commutes, try both ways.
2005 if (V1 == B && MaskedValueIsZero(V2, C2))
2006 return ReplaceInstUsesWith(I, A);
2007 if (V2 == B && MaskedValueIsZero(V1, C2))
2008 return ReplaceInstUsesWith(I, A);
2010 // Or commutes, try both ways.
2011 if ((C1->getRawValue() & (C1->getRawValue()+1)) == 0 &&
2012 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
2013 // Add commutes, try both ways.
2014 if (V1 == A && MaskedValueIsZero(V2, C1))
2015 return ReplaceInstUsesWith(I, B);
2016 if (V2 == A && MaskedValueIsZero(V1, C1))
2017 return ReplaceInstUsesWith(I, B);
2022 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
2023 if (A == Op1) // ~A | A == -1
2024 return ReplaceInstUsesWith(I,
2025 ConstantIntegral::getAllOnesValue(I.getType()));
2029 // Note, A is still live here!
2030 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
2032 return ReplaceInstUsesWith(I,
2033 ConstantIntegral::getAllOnesValue(I.getType()));
2035 // (~A | ~B) == (~(A & B)) - De Morgan's Law
2036 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
2037 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
2038 I.getName()+".demorgan"), I);
2039 return BinaryOperator::createNot(And);
2043 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
2044 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
2045 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2048 Value *LHSVal, *RHSVal;
2049 ConstantInt *LHSCst, *RHSCst;
2050 Instruction::BinaryOps LHSCC, RHSCC;
2051 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
2052 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
2053 if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
2054 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
2055 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
2056 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
2057 // Ensure that the larger constant is on the RHS.
2058 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
2059 SetCondInst *LHS = cast<SetCondInst>(Op0);
2060 if (cast<ConstantBool>(Cmp)->getValue()) {
2061 std::swap(LHS, RHS);
2062 std::swap(LHSCst, RHSCst);
2063 std::swap(LHSCC, RHSCC);
2066 // At this point, we know we have have two setcc instructions
2067 // comparing a value against two constants and or'ing the result
2068 // together. Because of the above check, we know that we only have
2069 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
2070 // FoldSetCCLogical check above), that the two constants are not
2072 assert(LHSCst != RHSCst && "Compares not folded above?");
2075 default: assert(0 && "Unknown integer condition code!");
2076 case Instruction::SetEQ:
2078 default: assert(0 && "Unknown integer condition code!");
2079 case Instruction::SetEQ:
2080 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
2081 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
2082 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
2083 LHSVal->getName()+".off");
2084 InsertNewInstBefore(Add, I);
2085 const Type *UnsType = Add->getType()->getUnsignedVersion();
2086 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
2087 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
2088 AddCST = ConstantExpr::getCast(AddCST, UnsType);
2089 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
2091 break; // (X == 13 | X == 15) -> no change
2093 case Instruction::SetGT: // (X == 13 | X > 14) -> no change
2095 case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
2096 case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
2097 return ReplaceInstUsesWith(I, RHS);
2100 case Instruction::SetNE:
2102 default: assert(0 && "Unknown integer condition code!");
2103 case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
2104 case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
2105 return ReplaceInstUsesWith(I, LHS);
2106 case Instruction::SetNE: // (X != 13 | X != 15) -> true
2107 case Instruction::SetLT: // (X != 13 | X < 15) -> true
2108 return ReplaceInstUsesWith(I, ConstantBool::True);
2111 case Instruction::SetLT:
2113 default: assert(0 && "Unknown integer condition code!");
2114 case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
2116 case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
2117 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
2118 case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
2119 case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
2120 return ReplaceInstUsesWith(I, RHS);
2123 case Instruction::SetGT:
2125 default: assert(0 && "Unknown integer condition code!");
2126 case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
2127 case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
2128 return ReplaceInstUsesWith(I, LHS);
2129 case Instruction::SetNE: // (X > 13 | X != 15) -> true
2130 case Instruction::SetLT: // (X > 13 | X < 15) -> true
2131 return ReplaceInstUsesWith(I, ConstantBool::True);
2137 return Changed ? &I : 0;
2140 // XorSelf - Implements: X ^ X --> 0
2143 XorSelf(Value *rhs) : RHS(rhs) {}
2144 bool shouldApply(Value *LHS) const { return LHS == RHS; }
2145 Instruction *apply(BinaryOperator &Xor) const {
2151 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
2152 bool Changed = SimplifyCommutative(I);
2153 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2155 if (isa<UndefValue>(Op1))
2156 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
2158 // xor X, X = 0, even if X is nested in a sequence of Xor's.
2159 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
2160 assert(Result == &I && "AssociativeOpt didn't work?");
2161 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2164 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2166 if (RHS->isNullValue())
2167 return ReplaceInstUsesWith(I, Op0);
2169 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2170 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
2171 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
2172 if (RHS == ConstantBool::True && SCI->hasOneUse())
2173 return new SetCondInst(SCI->getInverseCondition(),
2174 SCI->getOperand(0), SCI->getOperand(1));
2176 // ~(c-X) == X-c-1 == X+(-c-1)
2177 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
2178 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
2179 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
2180 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
2181 ConstantInt::get(I.getType(), 1));
2182 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
2185 // ~(~X & Y) --> (X | ~Y)
2186 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
2187 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
2188 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
2190 BinaryOperator::createNot(Op0I->getOperand(1),
2191 Op0I->getOperand(1)->getName()+".not");
2192 InsertNewInstBefore(NotY, I);
2193 return BinaryOperator::createOr(Op0NotVal, NotY);
2197 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
2198 switch (Op0I->getOpcode()) {
2199 case Instruction::Add:
2200 // ~(X-c) --> (-c-1)-X
2201 if (RHS->isAllOnesValue()) {
2202 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
2203 return BinaryOperator::createSub(
2204 ConstantExpr::getSub(NegOp0CI,
2205 ConstantInt::get(I.getType(), 1)),
2206 Op0I->getOperand(0));
2209 case Instruction::And:
2210 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
2211 if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue())
2212 return BinaryOperator::createOr(Op0, RHS);
2214 case Instruction::Or:
2215 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
2216 if (ConstantExpr::getAnd(RHS, Op0CI) == RHS)
2217 return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS));
2223 // Try to fold constant and into select arguments.
2224 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2225 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2227 if (isa<PHINode>(Op0))
2228 if (Instruction *NV = FoldOpIntoPhi(I))
2232 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
2234 return ReplaceInstUsesWith(I,
2235 ConstantIntegral::getAllOnesValue(I.getType()));
2237 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
2239 return ReplaceInstUsesWith(I,
2240 ConstantIntegral::getAllOnesValue(I.getType()));
2242 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
2243 if (Op1I->getOpcode() == Instruction::Or) {
2244 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
2245 cast<BinaryOperator>(Op1I)->swapOperands();
2247 std::swap(Op0, Op1);
2248 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
2250 std::swap(Op0, Op1);
2252 } else if (Op1I->getOpcode() == Instruction::Xor) {
2253 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
2254 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
2255 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
2256 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
2259 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
2260 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
2261 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
2262 cast<BinaryOperator>(Op0I)->swapOperands();
2263 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
2264 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
2265 Op1->getName()+".not"), I);
2266 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
2268 } else if (Op0I->getOpcode() == Instruction::Xor) {
2269 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
2270 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2271 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
2272 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2275 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
2276 Value *A, *B; ConstantInt *C1, *C2;
2277 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2278 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) &&
2279 ConstantExpr::getAnd(C1, C2)->isNullValue())
2280 return BinaryOperator::createOr(Op0, Op1);
2282 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
2283 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
2284 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2287 return Changed ? &I : 0;
2290 /// MulWithOverflow - Compute Result = In1*In2, returning true if the result
2291 /// overflowed for this type.
2292 static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2294 Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
2295 return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
2298 static bool isPositive(ConstantInt *C) {
2299 return cast<ConstantSInt>(C)->getValue() >= 0;
2302 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
2303 /// overflowed for this type.
2304 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2306 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
2308 if (In1->getType()->isUnsigned())
2309 return cast<ConstantUInt>(Result)->getValue() <
2310 cast<ConstantUInt>(In1)->getValue();
2311 if (isPositive(In1) != isPositive(In2))
2313 if (isPositive(In1))
2314 return cast<ConstantSInt>(Result)->getValue() <
2315 cast<ConstantSInt>(In1)->getValue();
2316 return cast<ConstantSInt>(Result)->getValue() >
2317 cast<ConstantSInt>(In1)->getValue();
2320 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
2321 /// code necessary to compute the offset from the base pointer (without adding
2322 /// in the base pointer). Return the result as a signed integer of intptr size.
2323 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
2324 TargetData &TD = IC.getTargetData();
2325 gep_type_iterator GTI = gep_type_begin(GEP);
2326 const Type *UIntPtrTy = TD.getIntPtrType();
2327 const Type *SIntPtrTy = UIntPtrTy->getSignedVersion();
2328 Value *Result = Constant::getNullValue(SIntPtrTy);
2330 // Build a mask for high order bits.
2331 uint64_t PtrSizeMask = ~0ULL;
2332 PtrSizeMask >>= 64-(TD.getPointerSize()*8);
2334 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
2335 Value *Op = GEP->getOperand(i);
2336 uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask;
2337 Constant *Scale = ConstantExpr::getCast(ConstantUInt::get(UIntPtrTy, Size),
2339 if (Constant *OpC = dyn_cast<Constant>(Op)) {
2340 if (!OpC->isNullValue()) {
2341 OpC = ConstantExpr::getCast(OpC, SIntPtrTy);
2342 Scale = ConstantExpr::getMul(OpC, Scale);
2343 if (Constant *RC = dyn_cast<Constant>(Result))
2344 Result = ConstantExpr::getAdd(RC, Scale);
2346 // Emit an add instruction.
2347 Result = IC.InsertNewInstBefore(
2348 BinaryOperator::createAdd(Result, Scale,
2349 GEP->getName()+".offs"), I);
2353 // Convert to correct type.
2354 Op = IC.InsertNewInstBefore(new CastInst(Op, SIntPtrTy,
2355 Op->getName()+".c"), I);
2357 // We'll let instcombine(mul) convert this to a shl if possible.
2358 Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
2359 GEP->getName()+".idx"), I);
2361 // Emit an add instruction.
2362 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
2363 GEP->getName()+".offs"), I);
2369 /// FoldGEPSetCC - Fold comparisons between a GEP instruction and something
2370 /// else. At this point we know that the GEP is on the LHS of the comparison.
2371 Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS,
2372 Instruction::BinaryOps Cond,
2374 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
2376 if (CastInst *CI = dyn_cast<CastInst>(RHS))
2377 if (isa<PointerType>(CI->getOperand(0)->getType()))
2378 RHS = CI->getOperand(0);
2380 Value *PtrBase = GEPLHS->getOperand(0);
2381 if (PtrBase == RHS) {
2382 // As an optimization, we don't actually have to compute the actual value of
2383 // OFFSET if this is a seteq or setne comparison, just return whether each
2384 // index is zero or not.
2385 if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) {
2386 Instruction *InVal = 0;
2387 gep_type_iterator GTI = gep_type_begin(GEPLHS);
2388 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
2390 if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
2391 if (isa<UndefValue>(C)) // undef index -> undef.
2392 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
2393 if (C->isNullValue())
2395 else if (TD->getTypeSize(GTI.getIndexedType()) == 0) {
2396 EmitIt = false; // This is indexing into a zero sized array?
2397 } else if (isa<ConstantInt>(C))
2398 return ReplaceInstUsesWith(I, // No comparison is needed here.
2399 ConstantBool::get(Cond == Instruction::SetNE));
2404 new SetCondInst(Cond, GEPLHS->getOperand(i),
2405 Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
2409 InVal = InsertNewInstBefore(InVal, I);
2410 InsertNewInstBefore(Comp, I);
2411 if (Cond == Instruction::SetNE) // True if any are unequal
2412 InVal = BinaryOperator::createOr(InVal, Comp);
2413 else // True if all are equal
2414 InVal = BinaryOperator::createAnd(InVal, Comp);
2422 ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0
2423 ConstantBool::get(Cond == Instruction::SetEQ));
2426 // Only lower this if the setcc is the only user of the GEP or if we expect
2427 // the result to fold to a constant!
2428 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
2429 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
2430 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
2431 return new SetCondInst(Cond, Offset,
2432 Constant::getNullValue(Offset->getType()));
2434 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
2435 // If the base pointers are different, but the indices are the same, just
2436 // compare the base pointer.
2437 if (PtrBase != GEPRHS->getOperand(0)) {
2438 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
2439 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
2440 GEPRHS->getOperand(0)->getType();
2442 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2443 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2444 IndicesTheSame = false;
2448 // If all indices are the same, just compare the base pointers.
2450 return new SetCondInst(Cond, GEPLHS->getOperand(0),
2451 GEPRHS->getOperand(0));
2453 // Otherwise, the base pointers are different and the indices are
2454 // different, bail out.
2458 // If one of the GEPs has all zero indices, recurse.
2459 bool AllZeros = true;
2460 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2461 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
2462 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
2467 return FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0),
2468 SetCondInst::getSwappedCondition(Cond), I);
2470 // If the other GEP has all zero indices, recurse.
2472 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2473 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
2474 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
2479 return FoldGEPSetCC(GEPLHS, GEPRHS->getOperand(0), Cond, I);
2481 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
2482 // If the GEPs only differ by one index, compare it.
2483 unsigned NumDifferences = 0; // Keep track of # differences.
2484 unsigned DiffOperand = 0; // The operand that differs.
2485 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2486 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2487 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
2488 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
2489 // Irreconcilable differences.
2493 if (NumDifferences++) break;
2498 if (NumDifferences == 0) // SAME GEP?
2499 return ReplaceInstUsesWith(I, // No comparison is needed here.
2500 ConstantBool::get(Cond == Instruction::SetEQ));
2501 else if (NumDifferences == 1) {
2502 Value *LHSV = GEPLHS->getOperand(DiffOperand);
2503 Value *RHSV = GEPRHS->getOperand(DiffOperand);
2505 // Convert the operands to signed values to make sure to perform a
2506 // signed comparison.
2507 const Type *NewTy = LHSV->getType()->getSignedVersion();
2508 if (LHSV->getType() != NewTy)
2509 LHSV = InsertNewInstBefore(new CastInst(LHSV, NewTy,
2510 LHSV->getName()), I);
2511 if (RHSV->getType() != NewTy)
2512 RHSV = InsertNewInstBefore(new CastInst(RHSV, NewTy,
2513 RHSV->getName()), I);
2514 return new SetCondInst(Cond, LHSV, RHSV);
2518 // Only lower this if the setcc is the only user of the GEP or if we expect
2519 // the result to fold to a constant!
2520 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
2521 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
2522 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
2523 Value *L = EmitGEPOffset(GEPLHS, I, *this);
2524 Value *R = EmitGEPOffset(GEPRHS, I, *this);
2525 return new SetCondInst(Cond, L, R);
2532 Instruction *InstCombiner::visitSetCondInst(SetCondInst &I) {
2533 bool Changed = SimplifyCommutative(I);
2534 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2535 const Type *Ty = Op0->getType();
2539 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
2541 if (isa<UndefValue>(Op1)) // X setcc undef -> undef
2542 return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
2544 // setcc <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
2545 // addresses never equal each other! We already know that Op0 != Op1.
2546 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
2547 isa<ConstantPointerNull>(Op0)) &&
2548 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
2549 isa<ConstantPointerNull>(Op1)))
2550 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
2552 // setcc's with boolean values can always be turned into bitwise operations
2553 if (Ty == Type::BoolTy) {
2554 switch (I.getOpcode()) {
2555 default: assert(0 && "Invalid setcc instruction!");
2556 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
2557 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
2558 InsertNewInstBefore(Xor, I);
2559 return BinaryOperator::createNot(Xor);
2561 case Instruction::SetNE:
2562 return BinaryOperator::createXor(Op0, Op1);
2564 case Instruction::SetGT:
2565 std::swap(Op0, Op1); // Change setgt -> setlt
2567 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
2568 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2569 InsertNewInstBefore(Not, I);
2570 return BinaryOperator::createAnd(Not, Op1);
2572 case Instruction::SetGE:
2573 std::swap(Op0, Op1); // Change setge -> setle
2575 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
2576 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2577 InsertNewInstBefore(Not, I);
2578 return BinaryOperator::createOr(Not, Op1);
2583 // See if we are doing a comparison between a constant and an instruction that
2584 // can be folded into the comparison.
2585 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2586 // Check to see if we are comparing against the minimum or maximum value...
2587 if (CI->isMinValue()) {
2588 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
2589 return ReplaceInstUsesWith(I, ConstantBool::False);
2590 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
2591 return ReplaceInstUsesWith(I, ConstantBool::True);
2592 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
2593 return BinaryOperator::createSetEQ(Op0, Op1);
2594 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
2595 return BinaryOperator::createSetNE(Op0, Op1);
2597 } else if (CI->isMaxValue()) {
2598 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
2599 return ReplaceInstUsesWith(I, ConstantBool::False);
2600 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
2601 return ReplaceInstUsesWith(I, ConstantBool::True);
2602 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
2603 return BinaryOperator::createSetEQ(Op0, Op1);
2604 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
2605 return BinaryOperator::createSetNE(Op0, Op1);
2607 // Comparing against a value really close to min or max?
2608 } else if (isMinValuePlusOne(CI)) {
2609 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
2610 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
2611 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
2612 return BinaryOperator::createSetNE(Op0, SubOne(CI));
2614 } else if (isMaxValueMinusOne(CI)) {
2615 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
2616 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
2617 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
2618 return BinaryOperator::createSetNE(Op0, AddOne(CI));
2621 // If we still have a setle or setge instruction, turn it into the
2622 // appropriate setlt or setgt instruction. Since the border cases have
2623 // already been handled above, this requires little checking.
2625 if (I.getOpcode() == Instruction::SetLE)
2626 return BinaryOperator::createSetLT(Op0, AddOne(CI));
2627 if (I.getOpcode() == Instruction::SetGE)
2628 return BinaryOperator::createSetGT(Op0, SubOne(CI));
2630 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
2631 switch (LHSI->getOpcode()) {
2632 case Instruction::And:
2633 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
2634 LHSI->getOperand(0)->hasOneUse()) {
2635 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
2636 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
2637 // happens a LOT in code produced by the C front-end, for bitfield
2639 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
2640 ConstantUInt *ShAmt;
2641 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
2642 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
2643 const Type *Ty = LHSI->getType();
2645 // We can fold this as long as we can't shift unknown bits
2646 // into the mask. This can only happen with signed shift
2647 // rights, as they sign-extend.
2649 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
2650 Shift->getType()->isUnsigned();
2652 // To test for the bad case of the signed shr, see if any
2653 // of the bits shifted in could be tested after the mask.
2654 int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue();
2655 if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
2657 Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal);
2659 ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
2660 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
2666 if (Shift->getOpcode() == Instruction::Shl)
2667 NewCst = ConstantExpr::getUShr(CI, ShAmt);
2669 NewCst = ConstantExpr::getShl(CI, ShAmt);
2671 // Check to see if we are shifting out any of the bits being
2673 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
2674 // If we shifted bits out, the fold is not going to work out.
2675 // As a special case, check to see if this means that the
2676 // result is always true or false now.
2677 if (I.getOpcode() == Instruction::SetEQ)
2678 return ReplaceInstUsesWith(I, ConstantBool::False);
2679 if (I.getOpcode() == Instruction::SetNE)
2680 return ReplaceInstUsesWith(I, ConstantBool::True);
2682 I.setOperand(1, NewCst);
2683 Constant *NewAndCST;
2684 if (Shift->getOpcode() == Instruction::Shl)
2685 NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
2687 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
2688 LHSI->setOperand(1, NewAndCST);
2689 LHSI->setOperand(0, Shift->getOperand(0));
2690 WorkList.push_back(Shift); // Shift is dead.
2691 AddUsesToWorkList(I);
2699 case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
2700 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2701 switch (I.getOpcode()) {
2703 case Instruction::SetEQ:
2704 case Instruction::SetNE: {
2705 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2707 // Check that the shift amount is in range. If not, don't perform
2708 // undefined shifts. When the shift is visited it will be
2710 if (ShAmt->getValue() >= TypeBits)
2713 // If we are comparing against bits always shifted out, the
2714 // comparison cannot succeed.
2716 ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
2717 if (Comp != CI) {// Comparing against a bit that we know is zero.
2718 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2719 Constant *Cst = ConstantBool::get(IsSetNE);
2720 return ReplaceInstUsesWith(I, Cst);
2723 if (LHSI->hasOneUse()) {
2724 // Otherwise strength reduce the shift into an and.
2725 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2726 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
2729 if (CI->getType()->isUnsigned()) {
2730 Mask = ConstantUInt::get(CI->getType(), Val);
2731 } else if (ShAmtVal != 0) {
2732 Mask = ConstantSInt::get(CI->getType(), Val);
2734 Mask = ConstantInt::getAllOnesValue(CI->getType());
2738 BinaryOperator::createAnd(LHSI->getOperand(0),
2739 Mask, LHSI->getName()+".mask");
2740 Value *And = InsertNewInstBefore(AndI, I);
2741 return new SetCondInst(I.getOpcode(), And,
2742 ConstantExpr::getUShr(CI, ShAmt));
2749 case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
2750 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2751 switch (I.getOpcode()) {
2753 case Instruction::SetEQ:
2754 case Instruction::SetNE: {
2756 // Check that the shift amount is in range. If not, don't perform
2757 // undefined shifts. When the shift is visited it will be
2759 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2760 if (ShAmt->getValue() >= TypeBits)
2763 // If we are comparing against bits always shifted out, the
2764 // comparison cannot succeed.
2766 ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
2768 if (Comp != CI) {// Comparing against a bit that we know is zero.
2769 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2770 Constant *Cst = ConstantBool::get(IsSetNE);
2771 return ReplaceInstUsesWith(I, Cst);
2774 if (LHSI->hasOneUse() || CI->isNullValue()) {
2775 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2777 // Otherwise strength reduce the shift into an and.
2778 uint64_t Val = ~0ULL; // All ones.
2779 Val <<= ShAmtVal; // Shift over to the right spot.
2782 if (CI->getType()->isUnsigned()) {
2783 Val &= ~0ULL >> (64-TypeBits);
2784 Mask = ConstantUInt::get(CI->getType(), Val);
2786 Mask = ConstantSInt::get(CI->getType(), Val);
2790 BinaryOperator::createAnd(LHSI->getOperand(0),
2791 Mask, LHSI->getName()+".mask");
2792 Value *And = InsertNewInstBefore(AndI, I);
2793 return new SetCondInst(I.getOpcode(), And,
2794 ConstantExpr::getShl(CI, ShAmt));
2802 case Instruction::Div:
2803 // Fold: (div X, C1) op C2 -> range check
2804 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
2805 // Fold this div into the comparison, producing a range check.
2806 // Determine, based on the divide type, what the range is being
2807 // checked. If there is an overflow on the low or high side, remember
2808 // it, otherwise compute the range [low, hi) bounding the new value.
2809 bool LoOverflow = false, HiOverflow = 0;
2810 ConstantInt *LoBound = 0, *HiBound = 0;
2813 bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
2815 Instruction::BinaryOps Opcode = I.getOpcode();
2817 if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
2818 } else if (LHSI->getType()->isUnsigned()) { // udiv
2820 LoOverflow = ProdOV;
2821 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
2822 } else if (isPositive(DivRHS)) { // Divisor is > 0.
2823 if (CI->isNullValue()) { // (X / pos) op 0
2825 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
2827 } else if (isPositive(CI)) { // (X / pos) op pos
2829 LoOverflow = ProdOV;
2830 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
2831 } else { // (X / pos) op neg
2832 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
2833 LoOverflow = AddWithOverflow(LoBound, Prod,
2834 cast<ConstantInt>(DivRHSH));
2836 HiOverflow = ProdOV;
2838 } else { // Divisor is < 0.
2839 if (CI->isNullValue()) { // (X / neg) op 0
2840 LoBound = AddOne(DivRHS);
2841 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
2842 if (HiBound == DivRHS)
2843 LoBound = 0; // - INTMIN = INTMIN
2844 } else if (isPositive(CI)) { // (X / neg) op pos
2845 HiOverflow = LoOverflow = ProdOV;
2847 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
2848 HiBound = AddOne(Prod);
2849 } else { // (X / neg) op neg
2851 LoOverflow = HiOverflow = ProdOV;
2852 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
2855 // Dividing by a negate swaps the condition.
2856 Opcode = SetCondInst::getSwappedCondition(Opcode);
2860 Value *X = LHSI->getOperand(0);
2862 default: assert(0 && "Unhandled setcc opcode!");
2863 case Instruction::SetEQ:
2864 if (LoOverflow && HiOverflow)
2865 return ReplaceInstUsesWith(I, ConstantBool::False);
2866 else if (HiOverflow)
2867 return new SetCondInst(Instruction::SetGE, X, LoBound);
2868 else if (LoOverflow)
2869 return new SetCondInst(Instruction::SetLT, X, HiBound);
2871 return InsertRangeTest(X, LoBound, HiBound, true, I);
2872 case Instruction::SetNE:
2873 if (LoOverflow && HiOverflow)
2874 return ReplaceInstUsesWith(I, ConstantBool::True);
2875 else if (HiOverflow)
2876 return new SetCondInst(Instruction::SetLT, X, LoBound);
2877 else if (LoOverflow)
2878 return new SetCondInst(Instruction::SetGE, X, HiBound);
2880 return InsertRangeTest(X, LoBound, HiBound, false, I);
2881 case Instruction::SetLT:
2883 return ReplaceInstUsesWith(I, ConstantBool::False);
2884 return new SetCondInst(Instruction::SetLT, X, LoBound);
2885 case Instruction::SetGT:
2887 return ReplaceInstUsesWith(I, ConstantBool::False);
2888 return new SetCondInst(Instruction::SetGE, X, HiBound);
2895 // Simplify seteq and setne instructions...
2896 if (I.getOpcode() == Instruction::SetEQ ||
2897 I.getOpcode() == Instruction::SetNE) {
2898 bool isSetNE = I.getOpcode() == Instruction::SetNE;
2900 // If the first operand is (and|or|xor) with a constant, and the second
2901 // operand is a constant, simplify a bit.
2902 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
2903 switch (BO->getOpcode()) {
2904 case Instruction::Rem:
2905 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
2906 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
2908 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1) {
2909 int64_t V = cast<ConstantSInt>(BO->getOperand(1))->getValue();
2910 if (isPowerOf2_64(V)) {
2911 unsigned L2 = Log2_64(V);
2912 const Type *UTy = BO->getType()->getUnsignedVersion();
2913 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
2915 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
2916 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
2917 RHSCst, BO->getName()), I);
2918 return BinaryOperator::create(I.getOpcode(), NewRem,
2919 Constant::getNullValue(UTy));
2924 case Instruction::Add:
2925 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
2926 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2927 if (BO->hasOneUse())
2928 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
2929 ConstantExpr::getSub(CI, BOp1C));
2930 } else if (CI->isNullValue()) {
2931 // Replace ((add A, B) != 0) with (A != -B) if A or B is
2932 // efficiently invertible, or if the add has just this one use.
2933 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
2935 if (Value *NegVal = dyn_castNegVal(BOp1))
2936 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
2937 else if (Value *NegVal = dyn_castNegVal(BOp0))
2938 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
2939 else if (BO->hasOneUse()) {
2940 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
2942 InsertNewInstBefore(Neg, I);
2943 return new SetCondInst(I.getOpcode(), BOp0, Neg);
2947 case Instruction::Xor:
2948 // For the xor case, we can xor two constants together, eliminating
2949 // the explicit xor.
2950 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
2951 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
2952 ConstantExpr::getXor(CI, BOC));
2955 case Instruction::Sub:
2956 // Replace (([sub|xor] A, B) != 0) with (A != B)
2957 if (CI->isNullValue())
2958 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
2962 case Instruction::Or:
2963 // If bits are being or'd in that are not present in the constant we
2964 // are comparing against, then the comparison could never succeed!
2965 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
2966 Constant *NotCI = ConstantExpr::getNot(CI);
2967 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
2968 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
2972 case Instruction::And:
2973 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2974 // If bits are being compared against that are and'd out, then the
2975 // comparison can never succeed!
2976 if (!ConstantExpr::getAnd(CI,
2977 ConstantExpr::getNot(BOC))->isNullValue())
2978 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
2980 // If we have ((X & C) == C), turn it into ((X & C) != 0).
2981 if (CI == BOC && isOneBitSet(CI))
2982 return new SetCondInst(isSetNE ? Instruction::SetEQ :
2983 Instruction::SetNE, Op0,
2984 Constant::getNullValue(CI->getType()));
2986 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
2987 // to be a signed value as appropriate.
2988 if (isSignBit(BOC)) {
2989 Value *X = BO->getOperand(0);
2990 // If 'X' is not signed, insert a cast now...
2991 if (!BOC->getType()->isSigned()) {
2992 const Type *DestTy = BOC->getType()->getSignedVersion();
2993 X = InsertCastBefore(X, DestTy, I);
2995 return new SetCondInst(isSetNE ? Instruction::SetLT :
2996 Instruction::SetGE, X,
2997 Constant::getNullValue(X->getType()));
3000 // ((X & ~7) == 0) --> X < 8
3001 if (CI->isNullValue() && isHighOnes(BOC)) {
3002 Value *X = BO->getOperand(0);
3003 Constant *NegX = ConstantExpr::getNeg(BOC);
3005 // If 'X' is signed, insert a cast now.
3006 if (NegX->getType()->isSigned()) {
3007 const Type *DestTy = NegX->getType()->getUnsignedVersion();
3008 X = InsertCastBefore(X, DestTy, I);
3009 NegX = ConstantExpr::getCast(NegX, DestTy);
3012 return new SetCondInst(isSetNE ? Instruction::SetGE :
3013 Instruction::SetLT, X, NegX);
3020 } else { // Not a SetEQ/SetNE
3021 // If the LHS is a cast from an integral value of the same size,
3022 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
3023 Value *CastOp = Cast->getOperand(0);
3024 const Type *SrcTy = CastOp->getType();
3025 unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits();
3026 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
3027 SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
3028 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
3029 "Source and destination signednesses should differ!");
3030 if (Cast->getType()->isSigned()) {
3031 // If this is a signed comparison, check for comparisons in the
3032 // vicinity of zero.
3033 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
3035 return BinaryOperator::createSetGT(CastOp,
3036 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize-1))-1));
3037 else if (I.getOpcode() == Instruction::SetGT &&
3038 cast<ConstantSInt>(CI)->getValue() == -1)
3039 // X > -1 => x < 128
3040 return BinaryOperator::createSetLT(CastOp,
3041 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize-1)));
3043 ConstantUInt *CUI = cast<ConstantUInt>(CI);
3044 if (I.getOpcode() == Instruction::SetLT &&
3045 CUI->getValue() == 1ULL << (SrcTySize-1))
3046 // X < 128 => X > -1
3047 return BinaryOperator::createSetGT(CastOp,
3048 ConstantSInt::get(SrcTy, -1));
3049 else if (I.getOpcode() == Instruction::SetGT &&
3050 CUI->getValue() == (1ULL << (SrcTySize-1))-1)
3052 return BinaryOperator::createSetLT(CastOp,
3053 Constant::getNullValue(SrcTy));
3060 // Handle setcc with constant RHS's that can be integer, FP or pointer.
3061 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
3062 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3063 switch (LHSI->getOpcode()) {
3064 case Instruction::GetElementPtr:
3065 if (RHSC->isNullValue()) {
3066 // Transform setcc GEP P, int 0, int 0, int 0, null -> setcc P, null
3067 bool isAllZeros = true;
3068 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
3069 if (!isa<Constant>(LHSI->getOperand(i)) ||
3070 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
3075 return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),
3076 Constant::getNullValue(LHSI->getOperand(0)->getType()));
3080 case Instruction::PHI:
3081 if (Instruction *NV = FoldOpIntoPhi(I))
3084 case Instruction::Select:
3085 // If either operand of the select is a constant, we can fold the
3086 // comparison into the select arms, which will cause one to be
3087 // constant folded and the select turned into a bitwise or.
3088 Value *Op1 = 0, *Op2 = 0;
3089 if (LHSI->hasOneUse()) {
3090 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
3091 // Fold the known value into the constant operand.
3092 Op1 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3093 // Insert a new SetCC of the other select operand.
3094 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3095 LHSI->getOperand(2), RHSC,
3097 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
3098 // Fold the known value into the constant operand.
3099 Op2 = ConstantExpr::get(I.getOpcode(), C, RHSC);
3100 // Insert a new SetCC of the other select operand.
3101 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
3102 LHSI->getOperand(1), RHSC,
3108 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
3113 // If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now.
3114 if (User *GEP = dyn_castGetElementPtr(Op0))
3115 if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I))
3117 if (User *GEP = dyn_castGetElementPtr(Op1))
3118 if (Instruction *NI = FoldGEPSetCC(GEP, Op0,
3119 SetCondInst::getSwappedCondition(I.getOpcode()), I))
3122 // Test to see if the operands of the setcc are casted versions of other
3123 // values. If the cast can be stripped off both arguments, we do so now.
3124 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3125 Value *CastOp0 = CI->getOperand(0);
3126 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
3127 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
3128 (I.getOpcode() == Instruction::SetEQ ||
3129 I.getOpcode() == Instruction::SetNE)) {
3130 // We keep moving the cast from the left operand over to the right
3131 // operand, where it can often be eliminated completely.
3134 // If operand #1 is a cast instruction, see if we can eliminate it as
3136 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
3137 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
3139 Op1 = CI2->getOperand(0);
3141 // If Op1 is a constant, we can fold the cast into the constant.
3142 if (Op1->getType() != Op0->getType())
3143 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
3144 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
3146 // Otherwise, cast the RHS right before the setcc
3147 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
3148 InsertNewInstBefore(cast<Instruction>(Op1), I);
3150 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
3153 // Handle the special case of: setcc (cast bool to X), <cst>
3154 // This comes up when you have code like
3157 // For generality, we handle any zero-extension of any operand comparison
3158 // with a constant or another cast from the same type.
3159 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
3160 if (Instruction *R = visitSetCondInstWithCastAndCast(I))
3163 return Changed ? &I : 0;
3166 // visitSetCondInstWithCastAndCast - Handle setcond (cast x to y), (cast/cst).
3167 // We only handle extending casts so far.
3169 Instruction *InstCombiner::visitSetCondInstWithCastAndCast(SetCondInst &SCI) {
3170 Value *LHSCIOp = cast<CastInst>(SCI.getOperand(0))->getOperand(0);
3171 const Type *SrcTy = LHSCIOp->getType();
3172 const Type *DestTy = SCI.getOperand(0)->getType();
3175 if (!DestTy->isIntegral() || !SrcTy->isIntegral())
3178 unsigned SrcBits = SrcTy->getPrimitiveSizeInBits();
3179 unsigned DestBits = DestTy->getPrimitiveSizeInBits();
3180 if (SrcBits >= DestBits) return 0; // Only handle extending cast.
3182 // Is this a sign or zero extension?
3183 bool isSignSrc = SrcTy->isSigned();
3184 bool isSignDest = DestTy->isSigned();
3186 if (CastInst *CI = dyn_cast<CastInst>(SCI.getOperand(1))) {
3187 // Not an extension from the same type?
3188 RHSCIOp = CI->getOperand(0);
3189 if (RHSCIOp->getType() != LHSCIOp->getType()) return 0;
3190 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(SCI.getOperand(1))) {
3191 // Compute the constant that would happen if we truncated to SrcTy then
3192 // reextended to DestTy.
3193 Constant *Res = ConstantExpr::getCast(CI, SrcTy);
3195 if (ConstantExpr::getCast(Res, DestTy) == CI) {
3198 // If the value cannot be represented in the shorter type, we cannot emit
3199 // a simple comparison.
3200 if (SCI.getOpcode() == Instruction::SetEQ)
3201 return ReplaceInstUsesWith(SCI, ConstantBool::False);
3202 if (SCI.getOpcode() == Instruction::SetNE)
3203 return ReplaceInstUsesWith(SCI, ConstantBool::True);
3205 // Evaluate the comparison for LT.
3207 if (DestTy->isSigned()) {
3208 // We're performing a signed comparison.
3210 // Signed extend and signed comparison.
3211 if (cast<ConstantSInt>(CI)->getValue() < 0) // X < (small) --> false
3212 Result = ConstantBool::False;
3214 Result = ConstantBool::True; // X < (large) --> true
3216 // Unsigned extend and signed comparison.
3217 if (cast<ConstantSInt>(CI)->getValue() < 0)
3218 Result = ConstantBool::False;
3220 Result = ConstantBool::True;
3223 // We're performing an unsigned comparison.
3225 // Unsigned extend & compare -> always true.
3226 Result = ConstantBool::True;
3228 // We're performing an unsigned comp with a sign extended value.
3229 // This is true if the input is >= 0. [aka >s -1]
3230 Constant *NegOne = ConstantIntegral::getAllOnesValue(SrcTy);
3231 Result = InsertNewInstBefore(BinaryOperator::createSetGT(LHSCIOp,
3232 NegOne, SCI.getName()), SCI);
3236 // Finally, return the value computed.
3237 if (SCI.getOpcode() == Instruction::SetLT) {
3238 return ReplaceInstUsesWith(SCI, Result);
3240 assert(SCI.getOpcode()==Instruction::SetGT &&"SetCC should be folded!");
3241 if (Constant *CI = dyn_cast<Constant>(Result))
3242 return ReplaceInstUsesWith(SCI, ConstantExpr::getNot(CI));
3244 return BinaryOperator::createNot(Result);
3251 // Okay, just insert a compare of the reduced operands now!
3252 return BinaryOperator::create(SCI.getOpcode(), LHSCIOp, RHSCIOp);
3255 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
3256 assert(I.getOperand(1)->getType() == Type::UByteTy);
3257 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3258 bool isLeftShift = I.getOpcode() == Instruction::Shl;
3260 // shl X, 0 == X and shr X, 0 == X
3261 // shl 0, X == 0 and shr 0, X == 0
3262 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
3263 Op0 == Constant::getNullValue(Op0->getType()))
3264 return ReplaceInstUsesWith(I, Op0);
3266 if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
3267 if (!isLeftShift && I.getType()->isSigned())
3268 return ReplaceInstUsesWith(I, Op0);
3269 else // undef << X -> 0 AND undef >>u X -> 0
3270 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3272 if (isa<UndefValue>(Op1)) {
3273 if (isLeftShift || I.getType()->isUnsigned())// X << undef, X >>u undef -> 0
3274 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3276 return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X
3279 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
3281 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
3282 if (CSI->isAllOnesValue())
3283 return ReplaceInstUsesWith(I, CSI);
3285 // Try to fold constant and into select arguments.
3286 if (isa<Constant>(Op0))
3287 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
3288 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3291 // See if we can turn a signed shr into an unsigned shr.
3292 if (!isLeftShift && I.getType()->isSigned()) {
3293 if (MaskedValueIsZero(Op0, ConstantInt::getMinValue(I.getType()))) {
3294 Value *V = InsertCastBefore(Op0, I.getType()->getUnsignedVersion(), I);
3295 V = InsertNewInstBefore(new ShiftInst(Instruction::Shr, V, Op1,
3297 return new CastInst(V, I.getType());
3301 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
3302 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
3303 // of a signed value.
3305 unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits();
3306 if (CUI->getValue() >= TypeBits) {
3307 if (!Op0->getType()->isSigned() || isLeftShift)
3308 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
3310 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
3315 // ((X*C1) << C2) == (X * (C1 << C2))
3316 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
3317 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
3318 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
3319 return BinaryOperator::createMul(BO->getOperand(0),
3320 ConstantExpr::getShl(BOOp, CUI));
3322 // Try to fold constant and into select arguments.
3323 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3324 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3326 if (isa<PHINode>(Op0))
3327 if (Instruction *NV = FoldOpIntoPhi(I))
3330 if (Op0->hasOneUse()) {
3331 // If this is a SHL of a sign-extending cast, see if we can turn the input
3332 // into a zero extending cast (a simple strength reduction).
3333 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3334 const Type *SrcTy = CI->getOperand(0)->getType();
3335 if (isLeftShift && SrcTy->isInteger() && SrcTy->isSigned() &&
3336 SrcTy->getPrimitiveSizeInBits() <
3337 CI->getType()->getPrimitiveSizeInBits()) {
3338 // We can change it to a zero extension if we are shifting out all of
3339 // the sign extended bits. To check this, form a mask of all of the
3340 // sign extend bits, then shift them left and see if we have anything
3342 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); // 1111
3343 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); // 00001111
3344 Mask = ConstantExpr::getNot(Mask); // 1's in the sign bits: 11110000
3345 if (ConstantExpr::getShl(Mask, CUI)->isNullValue()) {
3346 // If the shift is nuking all of the sign bits, change this to a
3347 // zero extension cast. To do this, cast the cast input to
3348 // unsigned, then to the requested size.
3349 Value *CastOp = CI->getOperand(0);
3351 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
3352 CI->getName()+".uns");
3353 NC = InsertNewInstBefore(NC, I);
3354 // Finally, insert a replacement for CI.
3355 NC = new CastInst(NC, CI->getType(), CI->getName());
3357 NC = InsertNewInstBefore(NC, I);
3358 WorkList.push_back(CI); // Delete CI later.
3359 I.setOperand(0, NC);
3360 return &I; // The SHL operand was modified.
3365 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
3366 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
3367 Value *V1, *V2, *V3;
3369 switch (Op0BO->getOpcode()) {
3371 case Instruction::Add:
3372 case Instruction::And:
3373 case Instruction::Or:
3374 case Instruction::Xor:
3375 // These operators commute.
3376 // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
3377 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
3378 match(Op0BO->getOperand(1),
3379 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == CUI) {
3380 Instruction *YS = new ShiftInst(Instruction::Shl,
3381 Op0BO->getOperand(0), CUI,
3383 InsertNewInstBefore(YS, I); // (Y << C)
3384 Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
3386 Op0BO->getOperand(1)->getName());
3387 InsertNewInstBefore(X, I); // (X + (Y << C))
3388 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
3389 C2 = ConstantExpr::getShl(C2, CUI);
3390 return BinaryOperator::createAnd(X, C2);
3393 // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
3394 if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
3395 match(Op0BO->getOperand(1),
3396 m_And(m_Shr(m_Value(V1), m_Value(V2)),
3397 m_ConstantInt(CC))) && V2 == CUI &&
3398 cast<BinaryOperator>(Op0BO->getOperand(1))->getOperand(0)->hasOneUse()) {
3399 Instruction *YS = new ShiftInst(Instruction::Shl,
3400 Op0BO->getOperand(0), CUI,
3402 InsertNewInstBefore(YS, I); // (Y << C)
3404 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, CUI),
3405 V1->getName()+".mask");
3406 InsertNewInstBefore(XM, I); // X & (CC << C)
3408 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
3412 case Instruction::Sub:
3413 // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
3414 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
3415 match(Op0BO->getOperand(0),
3416 m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == CUI) {
3417 Instruction *YS = new ShiftInst(Instruction::Shl,
3418 Op0BO->getOperand(1), CUI,
3420 InsertNewInstBefore(YS, I); // (Y << C)
3421 Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
3423 Op0BO->getOperand(0)->getName());
3424 InsertNewInstBefore(X, I); // (X + (Y << C))
3425 Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
3426 C2 = ConstantExpr::getShl(C2, CUI);
3427 return BinaryOperator::createAnd(X, C2);
3430 if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
3431 match(Op0BO->getOperand(0),
3432 m_And(m_Shr(m_Value(V1), m_Value(V2)),
3433 m_ConstantInt(CC))) && V2 == CUI &&
3434 cast<BinaryOperator>(Op0BO->getOperand(0))->getOperand(0)->hasOneUse()) {
3435 Instruction *YS = new ShiftInst(Instruction::Shl,
3436 Op0BO->getOperand(1), CUI,
3438 InsertNewInstBefore(YS, I); // (Y << C)
3440 BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, CUI),
3441 V1->getName()+".mask");
3442 InsertNewInstBefore(XM, I); // X & (CC << C)
3444 return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
3451 // If the operand is an bitwise operator with a constant RHS, and the
3452 // shift is the only use, we can pull it out of the shift.
3453 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
3454 bool isValid = true; // Valid only for And, Or, Xor
3455 bool highBitSet = false; // Transform if high bit of constant set?
3457 switch (Op0BO->getOpcode()) {
3458 default: isValid = false; break; // Do not perform transform!
3459 case Instruction::Add:
3460 isValid = isLeftShift;
3462 case Instruction::Or:
3463 case Instruction::Xor:
3466 case Instruction::And:
3471 // If this is a signed shift right, and the high bit is modified
3472 // by the logical operation, do not perform the transformation.
3473 // The highBitSet boolean indicates the value of the high bit of
3474 // the constant which would cause it to be modified for this
3477 if (isValid && !isLeftShift && !I.getType()->isUnsigned()) {
3478 uint64_t Val = Op0C->getRawValue();
3479 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
3483 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI);
3485 Instruction *NewShift =
3486 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI,
3489 InsertNewInstBefore(NewShift, I);
3491 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
3498 // If this is a shift of a shift, see if we can fold the two together...
3499 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
3500 if (ConstantUInt *ShiftAmt1C =
3501 dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) {
3502 unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getValue();
3503 unsigned ShiftAmt2 = (unsigned)CUI->getValue();
3505 // Check for (A << c1) << c2 and (A >> c1) >> c2
3506 if (I.getOpcode() == Op0SI->getOpcode()) {
3507 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
3508 if (Op0->getType()->getPrimitiveSizeInBits() < Amt)
3509 Amt = Op0->getType()->getPrimitiveSizeInBits();
3510 return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
3511 ConstantUInt::get(Type::UByteTy, Amt));
3514 // Check for (A << c1) >> c2 or visaversa. If we are dealing with
3515 // signed types, we can only support the (A >> c1) << c2 configuration,
3516 // because it can not turn an arbitrary bit of A into a sign bit.
3517 if (I.getType()->isUnsigned() || isLeftShift) {
3518 // Calculate bitmask for what gets shifted off the edge...
3519 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
3521 C = ConstantExpr::getShl(C, ShiftAmt1C);
3523 C = ConstantExpr::getShr(C, ShiftAmt1C);
3526 BinaryOperator::createAnd(Op0SI->getOperand(0), C,
3527 Op0SI->getOperand(0)->getName()+".mask");
3528 InsertNewInstBefore(Mask, I);
3530 // Figure out what flavor of shift we should use...
3531 if (ShiftAmt1 == ShiftAmt2)
3532 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
3533 else if (ShiftAmt1 < ShiftAmt2) {
3534 return new ShiftInst(I.getOpcode(), Mask,
3535 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
3537 return new ShiftInst(Op0SI->getOpcode(), Mask,
3538 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
3554 /// getCastType - In the future, we will split the cast instruction into these
3555 /// various types. Until then, we have to do the analysis here.
3556 static CastType getCastType(const Type *Src, const Type *Dest) {
3557 assert(Src->isIntegral() && Dest->isIntegral() &&
3558 "Only works on integral types!");
3559 unsigned SrcSize = Src->getPrimitiveSizeInBits();
3560 unsigned DestSize = Dest->getPrimitiveSizeInBits();
3562 if (SrcSize == DestSize) return Noop;
3563 if (SrcSize > DestSize) return Truncate;
3564 if (Src->isSigned()) return Signext;
3569 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
3572 static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
3573 const Type *DstTy, TargetData *TD) {
3575 // It is legal to eliminate the instruction if casting A->B->A if the sizes
3576 // are identical and the bits don't get reinterpreted (for example
3577 // int->float->int would not be allowed).
3578 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
3581 // If we are casting between pointer and integer types, treat pointers as
3582 // integers of the appropriate size for the code below.
3583 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
3584 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
3585 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
3587 // Allow free casting and conversion of sizes as long as the sign doesn't
3589 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
3590 CastType FirstCast = getCastType(SrcTy, MidTy);
3591 CastType SecondCast = getCastType(MidTy, DstTy);
3593 // Capture the effect of these two casts. If the result is a legal cast,
3594 // the CastType is stored here, otherwise a special code is used.
3595 static const unsigned CastResult[] = {
3596 // First cast is noop
3598 // First cast is a truncate
3599 1, 1, 4, 4, // trunc->extend is not safe to eliminate
3600 // First cast is a sign ext
3601 2, 5, 2, 4, // signext->zeroext never ok
3602 // First cast is a zero ext
3606 unsigned Result = CastResult[FirstCast*4+SecondCast];
3608 default: assert(0 && "Illegal table value!");
3613 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
3614 // truncates, we could eliminate more casts.
3615 return (unsigned)getCastType(SrcTy, DstTy) == Result;
3617 return false; // Not possible to eliminate this here.
3619 // Sign or zero extend followed by truncate is always ok if the result
3620 // is a truncate or noop.
3621 CastType ResultCast = getCastType(SrcTy, DstTy);
3622 if (ResultCast == Noop || ResultCast == Truncate)
3624 // Otherwise we are still growing the value, we are only safe if the
3625 // result will match the sign/zeroextendness of the result.
3626 return ResultCast == FirstCast;
3632 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
3633 if (V->getType() == Ty || isa<Constant>(V)) return false;
3634 if (const CastInst *CI = dyn_cast<CastInst>(V))
3635 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
3641 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
3642 /// InsertBefore instruction. This is specialized a bit to avoid inserting
3643 /// casts that are known to not do anything...
3645 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
3646 Instruction *InsertBefore) {
3647 if (V->getType() == DestTy) return V;
3648 if (Constant *C = dyn_cast<Constant>(V))
3649 return ConstantExpr::getCast(C, DestTy);
3651 CastInst *CI = new CastInst(V, DestTy, V->getName());
3652 InsertNewInstBefore(CI, *InsertBefore);
3656 // CastInst simplification
3658 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
3659 Value *Src = CI.getOperand(0);
3661 // If the user is casting a value to the same type, eliminate this cast
3663 if (CI.getType() == Src->getType())
3664 return ReplaceInstUsesWith(CI, Src);
3666 if (isa<UndefValue>(Src)) // cast undef -> undef
3667 return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
3669 // If casting the result of another cast instruction, try to eliminate this
3672 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
3673 Value *A = CSrc->getOperand(0);
3674 if (isEliminableCastOfCast(A->getType(), CSrc->getType(),
3675 CI.getType(), TD)) {
3676 // This instruction now refers directly to the cast's src operand. This
3677 // has a good chance of making CSrc dead.
3678 CI.setOperand(0, CSrc->getOperand(0));
3682 // If this is an A->B->A cast, and we are dealing with integral types, try
3683 // to convert this into a logical 'and' instruction.
3685 if (A->getType()->isInteger() &&
3686 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
3687 CSrc->getType()->isUnsigned() && // B->A cast must zero extend
3688 CSrc->getType()->getPrimitiveSizeInBits() <
3689 CI.getType()->getPrimitiveSizeInBits()&&
3690 A->getType()->getPrimitiveSizeInBits() ==
3691 CI.getType()->getPrimitiveSizeInBits()) {
3692 assert(CSrc->getType() != Type::ULongTy &&
3693 "Cannot have type bigger than ulong!");
3694 uint64_t AndValue = ~0ULL>>(64-CSrc->getType()->getPrimitiveSizeInBits());
3695 Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(),
3697 AndOp = ConstantExpr::getCast(AndOp, A->getType());
3698 Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
3699 if (And->getType() != CI.getType()) {
3700 And->setName(CSrc->getName()+".mask");
3701 InsertNewInstBefore(And, CI);
3702 And = new CastInst(And, CI.getType());
3708 // If this is a cast to bool, turn it into the appropriate setne instruction.
3709 if (CI.getType() == Type::BoolTy)
3710 return BinaryOperator::createSetNE(CI.getOperand(0),
3711 Constant::getNullValue(CI.getOperand(0)->getType()));
3713 // If casting the result of a getelementptr instruction with no offset, turn
3714 // this into a cast of the original pointer!
3716 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
3717 bool AllZeroOperands = true;
3718 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
3719 if (!isa<Constant>(GEP->getOperand(i)) ||
3720 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
3721 AllZeroOperands = false;
3724 if (AllZeroOperands) {
3725 CI.setOperand(0, GEP->getOperand(0));
3730 // If we are casting a malloc or alloca to a pointer to a type of the same
3731 // size, rewrite the allocation instruction to allocate the "right" type.
3733 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
3734 if (AI->hasOneUse() && !AI->isArrayAllocation())
3735 if (const PointerType *PTy = dyn_cast<PointerType>(CI.getType())) {
3736 // Get the type really allocated and the type casted to...
3737 const Type *AllocElTy = AI->getAllocatedType();
3738 const Type *CastElTy = PTy->getElementType();
3739 if (AllocElTy->isSized() && CastElTy->isSized()) {
3740 uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
3741 uint64_t CastElTySize = TD->getTypeSize(CastElTy);
3743 // If the allocation is for an even multiple of the cast type size
3744 if (CastElTySize && (AllocElTySize % CastElTySize == 0)) {
3745 Value *Amt = ConstantUInt::get(Type::UIntTy,
3746 AllocElTySize/CastElTySize);
3747 std::string Name = AI->getName(); AI->setName("");
3748 AllocationInst *New;
3749 if (isa<MallocInst>(AI))
3750 New = new MallocInst(CastElTy, Amt, Name);
3752 New = new AllocaInst(CastElTy, Amt, Name);
3753 InsertNewInstBefore(New, *AI);
3754 return ReplaceInstUsesWith(CI, New);
3759 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
3760 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
3762 if (isa<PHINode>(Src))
3763 if (Instruction *NV = FoldOpIntoPhi(CI))
3766 // If the source value is an instruction with only this use, we can attempt to
3767 // propagate the cast into the instruction. Also, only handle integral types
3769 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
3770 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
3771 CI.getType()->isInteger()) { // Don't mess with casts to bool here
3772 const Type *DestTy = CI.getType();
3773 unsigned SrcBitSize = Src->getType()->getPrimitiveSizeInBits();
3774 unsigned DestBitSize = DestTy->getPrimitiveSizeInBits();
3776 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
3777 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
3779 switch (SrcI->getOpcode()) {
3780 case Instruction::Add:
3781 case Instruction::Mul:
3782 case Instruction::And:
3783 case Instruction::Or:
3784 case Instruction::Xor:
3785 // If we are discarding information, or just changing the sign, rewrite.
3786 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
3787 // Don't insert two casts if they cannot be eliminated. We allow two
3788 // casts to be inserted if the sizes are the same. This could only be
3789 // converting signedness, which is a noop.
3790 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
3791 !ValueRequiresCast(Op0, DestTy, TD)) {
3792 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
3793 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
3794 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
3795 ->getOpcode(), Op0c, Op1c);
3799 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
3800 if (SrcBitSize == 1 && SrcI->getOpcode() == Instruction::Xor &&
3801 Op1 == ConstantBool::True &&
3802 (!Op0->hasOneUse() || !isa<SetCondInst>(Op0))) {
3803 Value *New = InsertOperandCastBefore(Op0, DestTy, &CI);
3804 return BinaryOperator::createXor(New,
3805 ConstantInt::get(CI.getType(), 1));
3808 case Instruction::Shl:
3809 // Allow changing the sign of the source operand. Do not allow changing
3810 // the size of the shift, UNLESS the shift amount is a constant. We
3811 // mush not change variable sized shifts to a smaller size, because it
3812 // is undefined to shift more bits out than exist in the value.
3813 if (DestBitSize == SrcBitSize ||
3814 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
3815 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
3816 return new ShiftInst(Instruction::Shl, Op0c, Op1);
3819 case Instruction::Shr:
3820 // If this is a signed shr, and if all bits shifted in are about to be
3821 // truncated off, turn it into an unsigned shr to allow greater
3823 if (DestBitSize < SrcBitSize && Src->getType()->isSigned() &&
3824 isa<ConstantInt>(Op1)) {
3825 unsigned ShiftAmt = cast<ConstantUInt>(Op1)->getValue();
3826 if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
3827 // Convert to unsigned.
3828 Value *N1 = InsertOperandCastBefore(Op0,
3829 Op0->getType()->getUnsignedVersion(), &CI);
3830 // Insert the new shift, which is now unsigned.
3831 N1 = InsertNewInstBefore(new ShiftInst(Instruction::Shr, N1,
3832 Op1, Src->getName()), CI);
3833 return new CastInst(N1, CI.getType());
3838 case Instruction::SetNE:
3839 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
3840 if (Op1C->getRawValue() == 0) {
3841 // If the input only has the low bit set, simplify directly.
3843 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
3844 // cast (X != 0) to int --> X if X&~1 == 0
3845 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
3846 if (CI.getType() == Op0->getType())
3847 return ReplaceInstUsesWith(CI, Op0);
3849 return new CastInst(Op0, CI.getType());
3852 // If the input is an and with a single bit, shift then simplify.
3853 ConstantInt *AndRHS;
3854 if (match(Op0, m_And(m_Value(), m_ConstantInt(AndRHS))))
3855 if (AndRHS->getRawValue() &&
3856 (AndRHS->getRawValue() & (AndRHS->getRawValue()-1)) == 0) {
3857 unsigned ShiftAmt = Log2_64(AndRHS->getRawValue());
3858 // Perform an unsigned shr by shiftamt. Convert input to
3859 // unsigned if it is signed.
3861 if (In->getType()->isSigned())
3862 In = InsertNewInstBefore(new CastInst(In,
3863 In->getType()->getUnsignedVersion(), In->getName()),CI);
3864 // Insert the shift to put the result in the low bit.
3865 In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In,
3866 ConstantInt::get(Type::UByteTy, ShiftAmt),
3867 In->getName()+".lobit"), CI);
3868 if (CI.getType() == In->getType())
3869 return ReplaceInstUsesWith(CI, In);
3871 return new CastInst(In, CI.getType());
3876 case Instruction::SetEQ:
3877 // We if we are just checking for a seteq of a single bit and casting it
3878 // to an integer. If so, shift the bit to the appropriate place then
3879 // cast to integer to avoid the comparison.
3880 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
3881 // Is Op1C a power of two or zero?
3882 if ((Op1C->getRawValue() & Op1C->getRawValue()-1) == 0) {
3883 // cast (X == 1) to int -> X iff X has only the low bit set.
3884 if (Op1C->getRawValue() == 1) {
3886 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
3887 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
3888 if (CI.getType() == Op0->getType())
3889 return ReplaceInstUsesWith(CI, Op0);
3891 return new CastInst(Op0, CI.getType());
3902 /// GetSelectFoldableOperands - We want to turn code that looks like this:
3904 /// %D = select %cond, %C, %A
3906 /// %C = select %cond, %B, 0
3909 /// Assuming that the specified instruction is an operand to the select, return
3910 /// a bitmask indicating which operands of this instruction are foldable if they
3911 /// equal the other incoming value of the select.
3913 static unsigned GetSelectFoldableOperands(Instruction *I) {
3914 switch (I->getOpcode()) {
3915 case Instruction::Add:
3916 case Instruction::Mul:
3917 case Instruction::And:
3918 case Instruction::Or:
3919 case Instruction::Xor:
3920 return 3; // Can fold through either operand.
3921 case Instruction::Sub: // Can only fold on the amount subtracted.
3922 case Instruction::Shl: // Can only fold on the shift amount.
3923 case Instruction::Shr:
3926 return 0; // Cannot fold
3930 /// GetSelectFoldableConstant - For the same transformation as the previous
3931 /// function, return the identity constant that goes into the select.
3932 static Constant *GetSelectFoldableConstant(Instruction *I) {
3933 switch (I->getOpcode()) {
3934 default: assert(0 && "This cannot happen!"); abort();
3935 case Instruction::Add:
3936 case Instruction::Sub:
3937 case Instruction::Or:
3938 case Instruction::Xor:
3939 return Constant::getNullValue(I->getType());
3940 case Instruction::Shl:
3941 case Instruction::Shr:
3942 return Constant::getNullValue(Type::UByteTy);
3943 case Instruction::And:
3944 return ConstantInt::getAllOnesValue(I->getType());
3945 case Instruction::Mul:
3946 return ConstantInt::get(I->getType(), 1);
3950 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
3951 /// have the same opcode and only one use each. Try to simplify this.
3952 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
3954 if (TI->getNumOperands() == 1) {
3955 // If this is a non-volatile load or a cast from the same type,
3957 if (TI->getOpcode() == Instruction::Cast) {
3958 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
3961 return 0; // unknown unary op.
3964 // Fold this by inserting a select from the input values.
3965 SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
3966 FI->getOperand(0), SI.getName()+".v");
3967 InsertNewInstBefore(NewSI, SI);
3968 return new CastInst(NewSI, TI->getType());
3971 // Only handle binary operators here.
3972 if (!isa<ShiftInst>(TI) && !isa<BinaryOperator>(TI))
3975 // Figure out if the operations have any operands in common.
3976 Value *MatchOp, *OtherOpT, *OtherOpF;
3978 if (TI->getOperand(0) == FI->getOperand(0)) {
3979 MatchOp = TI->getOperand(0);
3980 OtherOpT = TI->getOperand(1);
3981 OtherOpF = FI->getOperand(1);
3982 MatchIsOpZero = true;
3983 } else if (TI->getOperand(1) == FI->getOperand(1)) {
3984 MatchOp = TI->getOperand(1);
3985 OtherOpT = TI->getOperand(0);
3986 OtherOpF = FI->getOperand(0);
3987 MatchIsOpZero = false;
3988 } else if (!TI->isCommutative()) {
3990 } else if (TI->getOperand(0) == FI->getOperand(1)) {
3991 MatchOp = TI->getOperand(0);
3992 OtherOpT = TI->getOperand(1);
3993 OtherOpF = FI->getOperand(0);
3994 MatchIsOpZero = true;
3995 } else if (TI->getOperand(1) == FI->getOperand(0)) {
3996 MatchOp = TI->getOperand(1);
3997 OtherOpT = TI->getOperand(0);
3998 OtherOpF = FI->getOperand(1);
3999 MatchIsOpZero = true;
4004 // If we reach here, they do have operations in common.
4005 SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
4006 OtherOpF, SI.getName()+".v");
4007 InsertNewInstBefore(NewSI, SI);
4009 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
4011 return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
4013 return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
4016 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI);
4018 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp);
4022 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
4023 Value *CondVal = SI.getCondition();
4024 Value *TrueVal = SI.getTrueValue();
4025 Value *FalseVal = SI.getFalseValue();
4027 // select true, X, Y -> X
4028 // select false, X, Y -> Y
4029 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
4030 if (C == ConstantBool::True)
4031 return ReplaceInstUsesWith(SI, TrueVal);
4033 assert(C == ConstantBool::False);
4034 return ReplaceInstUsesWith(SI, FalseVal);
4037 // select C, X, X -> X
4038 if (TrueVal == FalseVal)
4039 return ReplaceInstUsesWith(SI, TrueVal);
4041 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
4042 return ReplaceInstUsesWith(SI, FalseVal);
4043 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
4044 return ReplaceInstUsesWith(SI, TrueVal);
4045 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
4046 if (isa<Constant>(TrueVal))
4047 return ReplaceInstUsesWith(SI, TrueVal);
4049 return ReplaceInstUsesWith(SI, FalseVal);
4052 if (SI.getType() == Type::BoolTy)
4053 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
4054 if (C == ConstantBool::True) {
4055 // Change: A = select B, true, C --> A = or B, C
4056 return BinaryOperator::createOr(CondVal, FalseVal);
4058 // Change: A = select B, false, C --> A = and !B, C
4060 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4061 "not."+CondVal->getName()), SI);
4062 return BinaryOperator::createAnd(NotCond, FalseVal);
4064 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
4065 if (C == ConstantBool::False) {
4066 // Change: A = select B, C, false --> A = and B, C
4067 return BinaryOperator::createAnd(CondVal, TrueVal);
4069 // Change: A = select B, C, true --> A = or !B, C
4071 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4072 "not."+CondVal->getName()), SI);
4073 return BinaryOperator::createOr(NotCond, TrueVal);
4077 // Selecting between two integer constants?
4078 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
4079 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
4080 // select C, 1, 0 -> cast C to int
4081 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
4082 return new CastInst(CondVal, SI.getType());
4083 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
4084 // select C, 0, 1 -> cast !C to int
4086 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
4087 "not."+CondVal->getName()), SI);
4088 return new CastInst(NotCond, SI.getType());
4091 // If one of the constants is zero (we know they can't both be) and we
4092 // have a setcc instruction with zero, and we have an 'and' with the
4093 // non-constant value, eliminate this whole mess. This corresponds to
4094 // cases like this: ((X & 27) ? 27 : 0)
4095 if (TrueValC->isNullValue() || FalseValC->isNullValue())
4096 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
4097 if ((IC->getOpcode() == Instruction::SetEQ ||
4098 IC->getOpcode() == Instruction::SetNE) &&
4099 isa<ConstantInt>(IC->getOperand(1)) &&
4100 cast<Constant>(IC->getOperand(1))->isNullValue())
4101 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
4102 if (ICA->getOpcode() == Instruction::And &&
4103 isa<ConstantInt>(ICA->getOperand(1)) &&
4104 (ICA->getOperand(1) == TrueValC ||
4105 ICA->getOperand(1) == FalseValC) &&
4106 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
4107 // Okay, now we know that everything is set up, we just don't
4108 // know whether we have a setne or seteq and whether the true or
4109 // false val is the zero.
4110 bool ShouldNotVal = !TrueValC->isNullValue();
4111 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
4114 V = InsertNewInstBefore(BinaryOperator::create(
4115 Instruction::Xor, V, ICA->getOperand(1)), SI);
4116 return ReplaceInstUsesWith(SI, V);
4120 // See if we are selecting two values based on a comparison of the two values.
4121 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
4122 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
4123 // Transform (X == Y) ? X : Y -> Y
4124 if (SCI->getOpcode() == Instruction::SetEQ)
4125 return ReplaceInstUsesWith(SI, FalseVal);
4126 // Transform (X != Y) ? X : Y -> X
4127 if (SCI->getOpcode() == Instruction::SetNE)
4128 return ReplaceInstUsesWith(SI, TrueVal);
4129 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
4131 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
4132 // Transform (X == Y) ? Y : X -> X
4133 if (SCI->getOpcode() == Instruction::SetEQ)
4134 return ReplaceInstUsesWith(SI, FalseVal);
4135 // Transform (X != Y) ? Y : X -> Y
4136 if (SCI->getOpcode() == Instruction::SetNE)
4137 return ReplaceInstUsesWith(SI, TrueVal);
4138 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
4142 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
4143 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
4144 if (TI->hasOneUse() && FI->hasOneUse()) {
4145 bool isInverse = false;
4146 Instruction *AddOp = 0, *SubOp = 0;
4148 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
4149 if (TI->getOpcode() == FI->getOpcode())
4150 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
4153 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
4154 // even legal for FP.
4155 if (TI->getOpcode() == Instruction::Sub &&
4156 FI->getOpcode() == Instruction::Add) {
4157 AddOp = FI; SubOp = TI;
4158 } else if (FI->getOpcode() == Instruction::Sub &&
4159 TI->getOpcode() == Instruction::Add) {
4160 AddOp = TI; SubOp = FI;
4164 Value *OtherAddOp = 0;
4165 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
4166 OtherAddOp = AddOp->getOperand(1);
4167 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
4168 OtherAddOp = AddOp->getOperand(0);
4172 // So at this point we know we have:
4173 // select C, (add X, Y), (sub X, ?)
4174 // We can do the transform profitably if either 'Y' = '?' or '?' is
4176 if (SubOp->getOperand(1) == AddOp ||
4177 isa<Constant>(SubOp->getOperand(1))) {
4179 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
4180 NegVal = ConstantExpr::getNeg(C);
4182 NegVal = InsertNewInstBefore(
4183 BinaryOperator::createNeg(SubOp->getOperand(1)), SI);
4186 Value *NewTrueOp = OtherAddOp;
4187 Value *NewFalseOp = NegVal;
4189 std::swap(NewTrueOp, NewFalseOp);
4190 Instruction *NewSel =
4191 new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
4193 NewSel = InsertNewInstBefore(NewSel, SI);
4194 return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
4200 // See if we can fold the select into one of our operands.
4201 if (SI.getType()->isInteger()) {
4202 // See the comment above GetSelectFoldableOperands for a description of the
4203 // transformation we are doing here.
4204 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
4205 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
4206 !isa<Constant>(FalseVal))
4207 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
4208 unsigned OpToFold = 0;
4209 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
4211 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
4216 Constant *C = GetSelectFoldableConstant(TVI);
4217 std::string Name = TVI->getName(); TVI->setName("");
4218 Instruction *NewSel =
4219 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
4221 InsertNewInstBefore(NewSel, SI);
4222 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
4223 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
4224 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
4225 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
4227 assert(0 && "Unknown instruction!!");
4232 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
4233 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
4234 !isa<Constant>(TrueVal))
4235 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
4236 unsigned OpToFold = 0;
4237 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
4239 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
4244 Constant *C = GetSelectFoldableConstant(FVI);
4245 std::string Name = FVI->getName(); FVI->setName("");
4246 Instruction *NewSel =
4247 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
4249 InsertNewInstBefore(NewSel, SI);
4250 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
4251 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
4252 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
4253 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
4255 assert(0 && "Unknown instruction!!");
4261 if (BinaryOperator::isNot(CondVal)) {
4262 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
4263 SI.setOperand(1, FalseVal);
4264 SI.setOperand(2, TrueVal);
4272 // CallInst simplification
4274 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
4275 // Intrinsics cannot occur in an invoke, so handle them here instead of in
4277 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(&CI)) {
4278 bool Changed = false;
4280 // memmove/cpy/set of zero bytes is a noop.
4281 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
4282 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
4284 // FIXME: Increase alignment here.
4286 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
4287 if (CI->getRawValue() == 1) {
4288 // Replace the instruction with just byte operations. We would
4289 // transform other cases to loads/stores, but we don't know if
4290 // alignment is sufficient.
4294 // If we have a memmove and the source operation is a constant global,
4295 // then the source and dest pointers can't alias, so we can change this
4296 // into a call to memcpy.
4297 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI))
4298 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
4299 if (GVSrc->isConstant()) {
4300 Module *M = CI.getParent()->getParent()->getParent();
4301 Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
4302 CI.getCalledFunction()->getFunctionType());
4303 CI.setOperand(0, MemCpy);
4307 if (Changed) return &CI;
4308 } else if (DbgStopPointInst *SPI = dyn_cast<DbgStopPointInst>(&CI)) {
4309 // If this stoppoint is at the same source location as the previous
4310 // stoppoint in the chain, it is not needed.
4311 if (DbgStopPointInst *PrevSPI =
4312 dyn_cast<DbgStopPointInst>(SPI->getChain()))
4313 if (SPI->getLineNo() == PrevSPI->getLineNo() &&
4314 SPI->getColNo() == PrevSPI->getColNo()) {
4315 SPI->replaceAllUsesWith(PrevSPI);
4316 return EraseInstFromFunction(CI);
4320 return visitCallSite(&CI);
4323 // InvokeInst simplification
4325 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
4326 return visitCallSite(&II);
4329 // visitCallSite - Improvements for call and invoke instructions.
4331 Instruction *InstCombiner::visitCallSite(CallSite CS) {
4332 bool Changed = false;
4334 // If the callee is a constexpr cast of a function, attempt to move the cast
4335 // to the arguments of the call/invoke.
4336 if (transformConstExprCastCall(CS)) return 0;
4338 Value *Callee = CS.getCalledValue();
4340 if (Function *CalleeF = dyn_cast<Function>(Callee))
4341 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
4342 Instruction *OldCall = CS.getInstruction();
4343 // If the call and callee calling conventions don't match, this call must
4344 // be unreachable, as the call is undefined.
4345 new StoreInst(ConstantBool::True,
4346 UndefValue::get(PointerType::get(Type::BoolTy)), OldCall);
4347 if (!OldCall->use_empty())
4348 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
4349 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
4350 return EraseInstFromFunction(*OldCall);
4354 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
4355 // This instruction is not reachable, just remove it. We insert a store to
4356 // undef so that we know that this code is not reachable, despite the fact
4357 // that we can't modify the CFG here.
4358 new StoreInst(ConstantBool::True,
4359 UndefValue::get(PointerType::get(Type::BoolTy)),
4360 CS.getInstruction());
4362 if (!CS.getInstruction()->use_empty())
4363 CS.getInstruction()->
4364 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
4366 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
4367 // Don't break the CFG, insert a dummy cond branch.
4368 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
4369 ConstantBool::True, II);
4371 return EraseInstFromFunction(*CS.getInstruction());
4374 const PointerType *PTy = cast<PointerType>(Callee->getType());
4375 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
4376 if (FTy->isVarArg()) {
4377 // See if we can optimize any arguments passed through the varargs area of
4379 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
4380 E = CS.arg_end(); I != E; ++I)
4381 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
4382 // If this cast does not effect the value passed through the varargs
4383 // area, we can eliminate the use of the cast.
4384 Value *Op = CI->getOperand(0);
4385 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
4392 return Changed ? CS.getInstruction() : 0;
4395 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
4396 // attempt to move the cast to the arguments of the call/invoke.
4398 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
4399 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
4400 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
4401 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
4403 Function *Callee = cast<Function>(CE->getOperand(0));
4404 Instruction *Caller = CS.getInstruction();
4406 // Okay, this is a cast from a function to a different type. Unless doing so
4407 // would cause a type conversion of one of our arguments, change this call to
4408 // be a direct call with arguments casted to the appropriate types.
4410 const FunctionType *FT = Callee->getFunctionType();
4411 const Type *OldRetTy = Caller->getType();
4413 // Check to see if we are changing the return type...
4414 if (OldRetTy != FT->getReturnType()) {
4415 if (Callee->isExternal() &&
4416 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
4417 !Caller->use_empty())
4418 return false; // Cannot transform this return value...
4420 // If the callsite is an invoke instruction, and the return value is used by
4421 // a PHI node in a successor, we cannot change the return type of the call
4422 // because there is no place to put the cast instruction (without breaking
4423 // the critical edge). Bail out in this case.
4424 if (!Caller->use_empty())
4425 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
4426 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
4428 if (PHINode *PN = dyn_cast<PHINode>(*UI))
4429 if (PN->getParent() == II->getNormalDest() ||
4430 PN->getParent() == II->getUnwindDest())
4434 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
4435 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
4437 CallSite::arg_iterator AI = CS.arg_begin();
4438 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
4439 const Type *ParamTy = FT->getParamType(i);
4440 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
4441 if (Callee->isExternal() && !isConvertible) return false;
4444 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
4445 Callee->isExternal())
4446 return false; // Do not delete arguments unless we have a function body...
4448 // Okay, we decided that this is a safe thing to do: go ahead and start
4449 // inserting cast instructions as necessary...
4450 std::vector<Value*> Args;
4451 Args.reserve(NumActualArgs);
4453 AI = CS.arg_begin();
4454 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
4455 const Type *ParamTy = FT->getParamType(i);
4456 if ((*AI)->getType() == ParamTy) {
4457 Args.push_back(*AI);
4459 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
4464 // If the function takes more arguments than the call was taking, add them
4466 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
4467 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
4469 // If we are removing arguments to the function, emit an obnoxious warning...
4470 if (FT->getNumParams() < NumActualArgs)
4471 if (!FT->isVarArg()) {
4472 std::cerr << "WARNING: While resolving call to function '"
4473 << Callee->getName() << "' arguments were dropped!\n";
4475 // Add all of the arguments in their promoted form to the arg list...
4476 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
4477 const Type *PTy = getPromotedType((*AI)->getType());
4478 if (PTy != (*AI)->getType()) {
4479 // Must promote to pass through va_arg area!
4480 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
4481 InsertNewInstBefore(Cast, *Caller);
4482 Args.push_back(Cast);
4484 Args.push_back(*AI);
4489 if (FT->getReturnType() == Type::VoidTy)
4490 Caller->setName(""); // Void type should not have a name...
4493 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4494 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
4495 Args, Caller->getName(), Caller);
4496 cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
4498 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
4499 if (cast<CallInst>(Caller)->isTailCall())
4500 cast<CallInst>(NC)->setTailCall();
4501 cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
4504 // Insert a cast of the return type as necessary...
4506 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
4507 if (NV->getType() != Type::VoidTy) {
4508 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
4510 // If this is an invoke instruction, we should insert it after the first
4511 // non-phi, instruction in the normal successor block.
4512 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4513 BasicBlock::iterator I = II->getNormalDest()->begin();
4514 while (isa<PHINode>(I)) ++I;
4515 InsertNewInstBefore(NC, *I);
4517 // Otherwise, it's a call, just insert cast right after the call instr
4518 InsertNewInstBefore(NC, *Caller);
4520 AddUsersToWorkList(*Caller);
4522 NV = UndefValue::get(Caller->getType());
4526 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
4527 Caller->replaceAllUsesWith(NV);
4528 Caller->getParent()->getInstList().erase(Caller);
4529 removeFromWorkList(Caller);
4534 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
4535 // operator and they all are only used by the PHI, PHI together their
4536 // inputs, and do the operation once, to the result of the PHI.
4537 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
4538 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
4540 // Scan the instruction, looking for input operations that can be folded away.
4541 // If all input operands to the phi are the same instruction (e.g. a cast from
4542 // the same type or "+42") we can pull the operation through the PHI, reducing
4543 // code size and simplifying code.
4544 Constant *ConstantOp = 0;
4545 const Type *CastSrcTy = 0;
4546 if (isa<CastInst>(FirstInst)) {
4547 CastSrcTy = FirstInst->getOperand(0)->getType();
4548 } else if (isa<BinaryOperator>(FirstInst) || isa<ShiftInst>(FirstInst)) {
4549 // Can fold binop or shift if the RHS is a constant.
4550 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
4551 if (ConstantOp == 0) return 0;
4553 return 0; // Cannot fold this operation.
4556 // Check to see if all arguments are the same operation.
4557 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4558 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
4559 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
4560 if (!I->hasOneUse() || I->getOpcode() != FirstInst->getOpcode())
4563 if (I->getOperand(0)->getType() != CastSrcTy)
4564 return 0; // Cast operation must match.
4565 } else if (I->getOperand(1) != ConstantOp) {
4570 // Okay, they are all the same operation. Create a new PHI node of the
4571 // correct type, and PHI together all of the LHS's of the instructions.
4572 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
4573 PN.getName()+".in");
4574 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
4576 Value *InVal = FirstInst->getOperand(0);
4577 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
4579 // Add all operands to the new PHI.
4580 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4581 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
4582 if (NewInVal != InVal)
4584 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
4589 // The new PHI unions all of the same values together. This is really
4590 // common, so we handle it intelligently here for compile-time speed.
4594 InsertNewInstBefore(NewPN, PN);
4598 // Insert and return the new operation.
4599 if (isa<CastInst>(FirstInst))
4600 return new CastInst(PhiVal, PN.getType());
4601 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
4602 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
4604 return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(),
4605 PhiVal, ConstantOp);
4608 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
4610 static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &PotentiallyDeadPHIs) {
4611 if (PN->use_empty()) return true;
4612 if (!PN->hasOneUse()) return false;
4614 // Remember this node, and if we find the cycle, return.
4615 if (!PotentiallyDeadPHIs.insert(PN).second)
4618 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
4619 return DeadPHICycle(PU, PotentiallyDeadPHIs);
4624 // PHINode simplification
4626 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
4627 if (Value *V = PN.hasConstantValue())
4628 return ReplaceInstUsesWith(PN, V);
4630 // If the only user of this instruction is a cast instruction, and all of the
4631 // incoming values are constants, change this PHI to merge together the casted
4634 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
4635 if (CI->getType() != PN.getType()) { // noop casts will be folded
4636 bool AllConstant = true;
4637 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
4638 if (!isa<Constant>(PN.getIncomingValue(i))) {
4639 AllConstant = false;
4643 // Make a new PHI with all casted values.
4644 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
4645 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
4646 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
4647 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
4648 PN.getIncomingBlock(i));
4651 // Update the cast instruction.
4652 CI->setOperand(0, New);
4653 WorkList.push_back(CI); // revisit the cast instruction to fold.
4654 WorkList.push_back(New); // Make sure to revisit the new Phi
4655 return &PN; // PN is now dead!
4659 // If all PHI operands are the same operation, pull them through the PHI,
4660 // reducing code size.
4661 if (isa<Instruction>(PN.getIncomingValue(0)) &&
4662 PN.getIncomingValue(0)->hasOneUse())
4663 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
4666 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
4667 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
4668 // PHI)... break the cycle.
4670 if (PHINode *PU = dyn_cast<PHINode>(PN.use_back())) {
4671 std::set<PHINode*> PotentiallyDeadPHIs;
4672 PotentiallyDeadPHIs.insert(&PN);
4673 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
4674 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
4680 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
4681 Instruction *InsertPoint,
4683 unsigned PS = IC->getTargetData().getPointerSize();
4684 const Type *VTy = V->getType();
4685 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
4686 // We must insert a cast to ensure we sign-extend.
4687 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
4688 V->getName()), *InsertPoint);
4689 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
4694 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
4695 Value *PtrOp = GEP.getOperand(0);
4696 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
4697 // If so, eliminate the noop.
4698 if (GEP.getNumOperands() == 1)
4699 return ReplaceInstUsesWith(GEP, PtrOp);
4701 if (isa<UndefValue>(GEP.getOperand(0)))
4702 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
4704 bool HasZeroPointerIndex = false;
4705 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
4706 HasZeroPointerIndex = C->isNullValue();
4708 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
4709 return ReplaceInstUsesWith(GEP, PtrOp);
4711 // Eliminate unneeded casts for indices.
4712 bool MadeChange = false;
4713 gep_type_iterator GTI = gep_type_begin(GEP);
4714 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
4715 if (isa<SequentialType>(*GTI)) {
4716 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
4717 Value *Src = CI->getOperand(0);
4718 const Type *SrcTy = Src->getType();
4719 const Type *DestTy = CI->getType();
4720 if (Src->getType()->isInteger()) {
4721 if (SrcTy->getPrimitiveSizeInBits() ==
4722 DestTy->getPrimitiveSizeInBits()) {
4723 // We can always eliminate a cast from ulong or long to the other.
4724 // We can always eliminate a cast from uint to int or the other on
4725 // 32-bit pointer platforms.
4726 if (DestTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()){
4728 GEP.setOperand(i, Src);
4730 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
4731 SrcTy->getPrimitiveSize() == 4) {
4732 // We can always eliminate a cast from int to [u]long. We can
4733 // eliminate a cast from uint to [u]long iff the target is a 32-bit
4735 if (SrcTy->isSigned() ||
4736 SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
4738 GEP.setOperand(i, Src);
4743 // If we are using a wider index than needed for this platform, shrink it
4744 // to what we need. If the incoming value needs a cast instruction,
4745 // insert it. This explicit cast can make subsequent optimizations more
4747 Value *Op = GEP.getOperand(i);
4748 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
4749 if (Constant *C = dyn_cast<Constant>(Op)) {
4750 GEP.setOperand(i, ConstantExpr::getCast(C,
4751 TD->getIntPtrType()->getSignedVersion()));
4754 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
4755 Op->getName()), GEP);
4756 GEP.setOperand(i, Op);
4760 // If this is a constant idx, make sure to canonicalize it to be a signed
4761 // operand, otherwise CSE and other optimizations are pessimized.
4762 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
4763 GEP.setOperand(i, ConstantExpr::getCast(CUI,
4764 CUI->getType()->getSignedVersion()));
4768 if (MadeChange) return &GEP;
4770 // Combine Indices - If the source pointer to this getelementptr instruction
4771 // is a getelementptr instruction, combine the indices of the two
4772 // getelementptr instructions into a single instruction.
4774 std::vector<Value*> SrcGEPOperands;
4775 if (User *Src = dyn_castGetElementPtr(PtrOp))
4776 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
4778 if (!SrcGEPOperands.empty()) {
4779 // Note that if our source is a gep chain itself that we wait for that
4780 // chain to be resolved before we perform this transformation. This
4781 // avoids us creating a TON of code in some cases.
4783 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
4784 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
4785 return 0; // Wait until our source is folded to completion.
4787 std::vector<Value *> Indices;
4789 // Find out whether the last index in the source GEP is a sequential idx.
4790 bool EndsWithSequential = false;
4791 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
4792 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
4793 EndsWithSequential = !isa<StructType>(*I);
4795 // Can we combine the two pointer arithmetics offsets?
4796 if (EndsWithSequential) {
4797 // Replace: gep (gep %P, long B), long A, ...
4798 // With: T = long A+B; gep %P, T, ...
4800 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
4801 if (SO1 == Constant::getNullValue(SO1->getType())) {
4803 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
4806 // If they aren't the same type, convert both to an integer of the
4807 // target's pointer size.
4808 if (SO1->getType() != GO1->getType()) {
4809 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
4810 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
4811 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
4812 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
4814 unsigned PS = TD->getPointerSize();
4815 if (SO1->getType()->getPrimitiveSize() == PS) {
4816 // Convert GO1 to SO1's type.
4817 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
4819 } else if (GO1->getType()->getPrimitiveSize() == PS) {
4820 // Convert SO1 to GO1's type.
4821 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
4823 const Type *PT = TD->getIntPtrType();
4824 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
4825 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
4829 if (isa<Constant>(SO1) && isa<Constant>(GO1))
4830 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
4832 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
4833 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
4837 // Recycle the GEP we already have if possible.
4838 if (SrcGEPOperands.size() == 2) {
4839 GEP.setOperand(0, SrcGEPOperands[0]);
4840 GEP.setOperand(1, Sum);
4843 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
4844 SrcGEPOperands.end()-1);
4845 Indices.push_back(Sum);
4846 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
4848 } else if (isa<Constant>(*GEP.idx_begin()) &&
4849 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
4850 SrcGEPOperands.size() != 1) {
4851 // Otherwise we can do the fold if the first index of the GEP is a zero
4852 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
4853 SrcGEPOperands.end());
4854 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
4857 if (!Indices.empty())
4858 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
4860 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
4861 // GEP of global variable. If all of the indices for this GEP are
4862 // constants, we can promote this to a constexpr instead of an instruction.
4864 // Scan for nonconstants...
4865 std::vector<Constant*> Indices;
4866 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
4867 for (; I != E && isa<Constant>(*I); ++I)
4868 Indices.push_back(cast<Constant>(*I));
4870 if (I == E) { // If they are all constants...
4871 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
4873 // Replace all uses of the GEP with the new constexpr...
4874 return ReplaceInstUsesWith(GEP, CE);
4876 } else if (Value *X = isCast(PtrOp)) { // Is the operand a cast?
4877 if (!isa<PointerType>(X->getType())) {
4878 // Not interesting. Source pointer must be a cast from pointer.
4879 } else if (HasZeroPointerIndex) {
4880 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
4881 // into : GEP [10 x ubyte]* X, long 0, ...
4883 // This occurs when the program declares an array extern like "int X[];"
4885 const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
4886 const PointerType *XTy = cast<PointerType>(X->getType());
4887 if (const ArrayType *XATy =
4888 dyn_cast<ArrayType>(XTy->getElementType()))
4889 if (const ArrayType *CATy =
4890 dyn_cast<ArrayType>(CPTy->getElementType()))
4891 if (CATy->getElementType() == XATy->getElementType()) {
4892 // At this point, we know that the cast source type is a pointer
4893 // to an array of the same type as the destination pointer
4894 // array. Because the array type is never stepped over (there
4895 // is a leading zero) we can fold the cast into this GEP.
4896 GEP.setOperand(0, X);
4899 } else if (GEP.getNumOperands() == 2) {
4900 // Transform things like:
4901 // %t = getelementptr ubyte* cast ([2 x int]* %str to uint*), uint %V
4902 // into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast
4903 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
4904 const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
4905 if (isa<ArrayType>(SrcElTy) &&
4906 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
4907 TD->getTypeSize(ResElTy)) {
4908 Value *V = InsertNewInstBefore(
4909 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
4910 GEP.getOperand(1), GEP.getName()), GEP);
4911 return new CastInst(V, GEP.getType());
4914 // Transform things like:
4915 // getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp
4916 // (where tmp = 8*tmp2) into:
4917 // getelementptr [100 x double]* %arr, int 0, int %tmp.2
4919 if (isa<ArrayType>(SrcElTy) &&
4920 (ResElTy == Type::SByteTy || ResElTy == Type::UByteTy)) {
4921 uint64_t ArrayEltSize =
4922 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType());
4924 // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
4925 // allow either a mul, shift, or constant here.
4927 ConstantInt *Scale = 0;
4928 if (ArrayEltSize == 1) {
4929 NewIdx = GEP.getOperand(1);
4930 Scale = ConstantInt::get(NewIdx->getType(), 1);
4931 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
4932 NewIdx = ConstantInt::get(CI->getType(), 1);
4934 } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
4935 if (Inst->getOpcode() == Instruction::Shl &&
4936 isa<ConstantInt>(Inst->getOperand(1))) {
4937 unsigned ShAmt =cast<ConstantUInt>(Inst->getOperand(1))->getValue();
4938 if (Inst->getType()->isSigned())
4939 Scale = ConstantSInt::get(Inst->getType(), 1ULL << ShAmt);
4941 Scale = ConstantUInt::get(Inst->getType(), 1ULL << ShAmt);
4942 NewIdx = Inst->getOperand(0);
4943 } else if (Inst->getOpcode() == Instruction::Mul &&
4944 isa<ConstantInt>(Inst->getOperand(1))) {
4945 Scale = cast<ConstantInt>(Inst->getOperand(1));
4946 NewIdx = Inst->getOperand(0);
4950 // If the index will be to exactly the right offset with the scale taken
4951 // out, perform the transformation.
4952 if (Scale && Scale->getRawValue() % ArrayEltSize == 0) {
4953 if (ConstantSInt *C = dyn_cast<ConstantSInt>(Scale))
4954 Scale = ConstantSInt::get(C->getType(),
4955 (int64_t)C->getRawValue() /
4956 (int64_t)ArrayEltSize);
4958 Scale = ConstantUInt::get(Scale->getType(),
4959 Scale->getRawValue() / ArrayEltSize);
4960 if (Scale->getRawValue() != 1) {
4961 Constant *C = ConstantExpr::getCast(Scale, NewIdx->getType());
4962 Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale");
4963 NewIdx = InsertNewInstBefore(Sc, GEP);
4966 // Insert the new GEP instruction.
4968 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
4969 NewIdx, GEP.getName());
4970 Idx = InsertNewInstBefore(Idx, GEP);
4971 return new CastInst(Idx, GEP.getType());
4980 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
4981 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
4982 if (AI.isArrayAllocation()) // Check C != 1
4983 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
4984 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
4985 AllocationInst *New = 0;
4987 // Create and insert the replacement instruction...
4988 if (isa<MallocInst>(AI))
4989 New = new MallocInst(NewTy, 0, AI.getName());
4991 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
4992 New = new AllocaInst(NewTy, 0, AI.getName());
4995 InsertNewInstBefore(New, AI);
4997 // Scan to the end of the allocation instructions, to skip over a block of
4998 // allocas if possible...
5000 BasicBlock::iterator It = New;
5001 while (isa<AllocationInst>(*It)) ++It;
5003 // Now that I is pointing to the first non-allocation-inst in the block,
5004 // insert our getelementptr instruction...
5006 Value *NullIdx = Constant::getNullValue(Type::IntTy);
5007 Value *V = new GetElementPtrInst(New, NullIdx, NullIdx,
5008 New->getName()+".sub", It);
5010 // Now make everything use the getelementptr instead of the original
5012 return ReplaceInstUsesWith(AI, V);
5013 } else if (isa<UndefValue>(AI.getArraySize())) {
5014 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5017 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
5018 // Note that we only do this for alloca's, because malloc should allocate and
5019 // return a unique pointer, even for a zero byte allocation.
5020 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
5021 TD->getTypeSize(AI.getAllocatedType()) == 0)
5022 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
5027 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
5028 Value *Op = FI.getOperand(0);
5030 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
5031 if (CastInst *CI = dyn_cast<CastInst>(Op))
5032 if (isa<PointerType>(CI->getOperand(0)->getType())) {
5033 FI.setOperand(0, CI->getOperand(0));
5037 // free undef -> unreachable.
5038 if (isa<UndefValue>(Op)) {
5039 // Insert a new store to null because we cannot modify the CFG here.
5040 new StoreInst(ConstantBool::True,
5041 UndefValue::get(PointerType::get(Type::BoolTy)), &FI);
5042 return EraseInstFromFunction(FI);
5045 // If we have 'free null' delete the instruction. This can happen in stl code
5046 // when lots of inlining happens.
5047 if (isa<ConstantPointerNull>(Op))
5048 return EraseInstFromFunction(FI);
5054 /// GetGEPGlobalInitializer - Given a constant, and a getelementptr
5055 /// constantexpr, return the constant value being addressed by the constant
5056 /// expression, or null if something is funny.
5058 static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
5059 if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
5060 return 0; // Do not allow stepping over the value!
5062 // Loop over all of the operands, tracking down which value we are
5064 gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
5065 for (++I; I != E; ++I)
5066 if (const StructType *STy = dyn_cast<StructType>(*I)) {
5067 ConstantUInt *CU = cast<ConstantUInt>(I.getOperand());
5068 assert(CU->getValue() < STy->getNumElements() &&
5069 "Struct index out of range!");
5070 unsigned El = (unsigned)CU->getValue();
5071 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
5072 C = CS->getOperand(El);
5073 } else if (isa<ConstantAggregateZero>(C)) {
5074 C = Constant::getNullValue(STy->getElementType(El));
5075 } else if (isa<UndefValue>(C)) {
5076 C = UndefValue::get(STy->getElementType(El));
5080 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
5081 const ArrayType *ATy = cast<ArrayType>(*I);
5082 if ((uint64_t)CI->getRawValue() >= ATy->getNumElements()) return 0;
5083 if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
5084 C = CA->getOperand((unsigned)CI->getRawValue());
5085 else if (isa<ConstantAggregateZero>(C))
5086 C = Constant::getNullValue(ATy->getElementType());
5087 else if (isa<UndefValue>(C))
5088 C = UndefValue::get(ATy->getElementType());
5097 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
5098 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
5099 User *CI = cast<User>(LI.getOperand(0));
5100 Value *CastOp = CI->getOperand(0);
5102 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5103 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5104 const Type *SrcPTy = SrcTy->getElementType();
5106 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5107 // If the source is an array, the code below will not succeed. Check to
5108 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5110 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5111 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5112 if (ASrcTy->getNumElements() != 0) {
5113 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5114 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5115 SrcTy = cast<PointerType>(CastOp->getType());
5116 SrcPTy = SrcTy->getElementType();
5119 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5120 // Do not allow turning this into a load of an integer, which is then
5121 // casted to a pointer, this pessimizes pointer analysis a lot.
5122 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
5123 IC.getTargetData().getTypeSize(SrcPTy) ==
5124 IC.getTargetData().getTypeSize(DestPTy)) {
5126 // Okay, we are casting from one integer or pointer type to another of
5127 // the same size. Instead of casting the pointer before the load, cast
5128 // the result of the loaded value.
5129 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
5131 LI.isVolatile()),LI);
5132 // Now cast the result of the load.
5133 return new CastInst(NewLoad, LI.getType());
5140 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
5141 /// from this value cannot trap. If it is not obviously safe to load from the
5142 /// specified pointer, we do a quick local scan of the basic block containing
5143 /// ScanFrom, to determine if the address is already accessed.
5144 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
5145 // If it is an alloca or global variable, it is always safe to load from.
5146 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
5148 // Otherwise, be a little bit agressive by scanning the local block where we
5149 // want to check to see if the pointer is already being loaded or stored
5150 // from/to. If so, the previous load or store would have already trapped,
5151 // so there is no harm doing an extra load (also, CSE will later eliminate
5152 // the load entirely).
5153 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
5158 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
5159 if (LI->getOperand(0) == V) return true;
5160 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
5161 if (SI->getOperand(1) == V) return true;
5167 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
5168 Value *Op = LI.getOperand(0);
5170 // load (cast X) --> cast (load X) iff safe
5171 if (CastInst *CI = dyn_cast<CastInst>(Op))
5172 if (Instruction *Res = InstCombineLoadCast(*this, LI))
5175 // None of the following transforms are legal for volatile loads.
5176 if (LI.isVolatile()) return 0;
5178 if (&LI.getParent()->front() != &LI) {
5179 BasicBlock::iterator BBI = &LI; --BBI;
5180 // If the instruction immediately before this is a store to the same
5181 // address, do a simple form of store->load forwarding.
5182 if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
5183 if (SI->getOperand(1) == LI.getOperand(0))
5184 return ReplaceInstUsesWith(LI, SI->getOperand(0));
5185 if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
5186 if (LIB->getOperand(0) == LI.getOperand(0))
5187 return ReplaceInstUsesWith(LI, LIB);
5190 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
5191 if (isa<ConstantPointerNull>(GEPI->getOperand(0)) ||
5192 isa<UndefValue>(GEPI->getOperand(0))) {
5193 // Insert a new store to null instruction before the load to indicate
5194 // that this code is not reachable. We do this instead of inserting
5195 // an unreachable instruction directly because we cannot modify the
5197 new StoreInst(UndefValue::get(LI.getType()),
5198 Constant::getNullValue(Op->getType()), &LI);
5199 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5202 if (Constant *C = dyn_cast<Constant>(Op)) {
5203 // load null/undef -> undef
5204 if ((C->isNullValue() || isa<UndefValue>(C))) {
5205 // Insert a new store to null instruction before the load to indicate that
5206 // this code is not reachable. We do this instead of inserting an
5207 // unreachable instruction directly because we cannot modify the CFG.
5208 new StoreInst(UndefValue::get(LI.getType()),
5209 Constant::getNullValue(Op->getType()), &LI);
5210 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5213 // Instcombine load (constant global) into the value loaded.
5214 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
5215 if (GV->isConstant() && !GV->isExternal())
5216 return ReplaceInstUsesWith(LI, GV->getInitializer());
5218 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
5219 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
5220 if (CE->getOpcode() == Instruction::GetElementPtr) {
5221 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
5222 if (GV->isConstant() && !GV->isExternal())
5223 if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
5224 return ReplaceInstUsesWith(LI, V);
5225 if (CE->getOperand(0)->isNullValue()) {
5226 // Insert a new store to null instruction before the load to indicate
5227 // that this code is not reachable. We do this instead of inserting
5228 // an unreachable instruction directly because we cannot modify the
5230 new StoreInst(UndefValue::get(LI.getType()),
5231 Constant::getNullValue(Op->getType()), &LI);
5232 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
5235 } else if (CE->getOpcode() == Instruction::Cast) {
5236 if (Instruction *Res = InstCombineLoadCast(*this, LI))
5241 if (Op->hasOneUse()) {
5242 // Change select and PHI nodes to select values instead of addresses: this
5243 // helps alias analysis out a lot, allows many others simplifications, and
5244 // exposes redundancy in the code.
5246 // Note that we cannot do the transformation unless we know that the
5247 // introduced loads cannot trap! Something like this is valid as long as
5248 // the condition is always false: load (select bool %C, int* null, int* %G),
5249 // but it would not be valid if we transformed it to load from null
5252 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
5253 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
5254 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
5255 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
5256 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
5257 SI->getOperand(1)->getName()+".val"), LI);
5258 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
5259 SI->getOperand(2)->getName()+".val"), LI);
5260 return new SelectInst(SI->getCondition(), V1, V2);
5263 // load (select (cond, null, P)) -> load P
5264 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
5265 if (C->isNullValue()) {
5266 LI.setOperand(0, SI->getOperand(2));
5270 // load (select (cond, P, null)) -> load P
5271 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
5272 if (C->isNullValue()) {
5273 LI.setOperand(0, SI->getOperand(1));
5277 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
5278 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
5279 bool Safe = PN->getParent() == LI.getParent();
5281 // Scan all of the instructions between the PHI and the load to make
5282 // sure there are no instructions that might possibly alter the value
5283 // loaded from the PHI.
5285 BasicBlock::iterator I = &LI;
5286 for (--I; !isa<PHINode>(I); --I)
5287 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
5293 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
5294 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
5295 PN->getIncomingBlock(i)->getTerminator()))
5300 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
5301 InsertNewInstBefore(NewPN, *PN);
5302 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
5304 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
5305 BasicBlock *BB = PN->getIncomingBlock(i);
5306 Value *&TheLoad = LoadMap[BB];
5308 Value *InVal = PN->getIncomingValue(i);
5309 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
5310 InVal->getName()+".val"),
5311 *BB->getTerminator());
5313 NewPN->addIncoming(TheLoad, BB);
5315 return ReplaceInstUsesWith(LI, NewPN);
5322 /// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store (cast V), P'
5324 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
5325 User *CI = cast<User>(SI.getOperand(1));
5326 Value *CastOp = CI->getOperand(0);
5328 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5329 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5330 const Type *SrcPTy = SrcTy->getElementType();
5332 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5333 // If the source is an array, the code below will not succeed. Check to
5334 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5336 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5337 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5338 if (ASrcTy->getNumElements() != 0) {
5339 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5340 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5341 SrcTy = cast<PointerType>(CastOp->getType());
5342 SrcPTy = SrcTy->getElementType();
5345 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5346 IC.getTargetData().getTypeSize(SrcPTy) ==
5347 IC.getTargetData().getTypeSize(DestPTy)) {
5349 // Okay, we are casting from one integer or pointer type to another of
5350 // the same size. Instead of casting the pointer before the store, cast
5351 // the value to be stored.
5353 if (Constant *C = dyn_cast<Constant>(SI.getOperand(0)))
5354 NewCast = ConstantExpr::getCast(C, SrcPTy);
5356 NewCast = IC.InsertNewInstBefore(new CastInst(SI.getOperand(0),
5358 SI.getOperand(0)->getName()+".c"), SI);
5360 return new StoreInst(NewCast, CastOp);
5367 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
5368 Value *Val = SI.getOperand(0);
5369 Value *Ptr = SI.getOperand(1);
5371 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
5372 removeFromWorkList(&SI);
5373 SI.eraseFromParent();
5378 if (SI.isVolatile()) return 0; // Don't hack volatile loads.
5380 // store X, null -> turns into 'unreachable' in SimplifyCFG
5381 if (isa<ConstantPointerNull>(Ptr)) {
5382 if (!isa<UndefValue>(Val)) {
5383 SI.setOperand(0, UndefValue::get(Val->getType()));
5384 if (Instruction *U = dyn_cast<Instruction>(Val))
5385 WorkList.push_back(U); // Dropped a use.
5388 return 0; // Do not modify these!
5391 // store undef, Ptr -> noop
5392 if (isa<UndefValue>(Val)) {
5393 removeFromWorkList(&SI);
5394 SI.eraseFromParent();
5399 // If the pointer destination is a cast, see if we can fold the cast into the
5401 if (CastInst *CI = dyn_cast<CastInst>(Ptr))
5402 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5404 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
5405 if (CE->getOpcode() == Instruction::Cast)
5406 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5410 // If this store is the last instruction in the basic block, and if the block
5411 // ends with an unconditional branch, try to move it to the successor block.
5412 BasicBlock::iterator BBI = &SI; ++BBI;
5413 if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
5414 if (BI->isUnconditional()) {
5415 // Check to see if the successor block has exactly two incoming edges. If
5416 // so, see if the other predecessor contains a store to the same location.
5417 // if so, insert a PHI node (if needed) and move the stores down.
5418 BasicBlock *Dest = BI->getSuccessor(0);
5420 pred_iterator PI = pred_begin(Dest);
5421 BasicBlock *Other = 0;
5422 if (*PI != BI->getParent())
5425 if (PI != pred_end(Dest)) {
5426 if (*PI != BI->getParent())
5431 if (++PI != pred_end(Dest))
5434 if (Other) { // If only one other pred...
5435 BBI = Other->getTerminator();
5436 // Make sure this other block ends in an unconditional branch and that
5437 // there is an instruction before the branch.
5438 if (isa<BranchInst>(BBI) && cast<BranchInst>(BBI)->isUnconditional() &&
5439 BBI != Other->begin()) {
5441 StoreInst *OtherStore = dyn_cast<StoreInst>(BBI);
5443 // If this instruction is a store to the same location.
5444 if (OtherStore && OtherStore->getOperand(1) == SI.getOperand(1)) {
5445 // Okay, we know we can perform this transformation. Insert a PHI
5446 // node now if we need it.
5447 Value *MergedVal = OtherStore->getOperand(0);
5448 if (MergedVal != SI.getOperand(0)) {
5449 PHINode *PN = new PHINode(MergedVal->getType(), "storemerge");
5450 PN->reserveOperandSpace(2);
5451 PN->addIncoming(SI.getOperand(0), SI.getParent());
5452 PN->addIncoming(OtherStore->getOperand(0), Other);
5453 MergedVal = InsertNewInstBefore(PN, Dest->front());
5456 // Advance to a place where it is safe to insert the new store and
5458 BBI = Dest->begin();
5459 while (isa<PHINode>(BBI)) ++BBI;
5460 InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
5461 OtherStore->isVolatile()), *BBI);
5463 // Nuke the old stores.
5464 removeFromWorkList(&SI);
5465 removeFromWorkList(OtherStore);
5466 SI.eraseFromParent();
5467 OtherStore->eraseFromParent();
5479 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
5480 // Change br (not X), label True, label False to: br X, label False, True
5482 BasicBlock *TrueDest;
5483 BasicBlock *FalseDest;
5484 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
5485 !isa<Constant>(X)) {
5486 // Swap Destinations and condition...
5488 BI.setSuccessor(0, FalseDest);
5489 BI.setSuccessor(1, TrueDest);
5493 // Cannonicalize setne -> seteq
5494 Instruction::BinaryOps Op; Value *Y;
5495 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
5496 TrueDest, FalseDest)))
5497 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
5498 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
5499 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
5500 std::string Name = I->getName(); I->setName("");
5501 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
5502 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
5503 // Swap Destinations and condition...
5504 BI.setCondition(NewSCC);
5505 BI.setSuccessor(0, FalseDest);
5506 BI.setSuccessor(1, TrueDest);
5507 removeFromWorkList(I);
5508 I->getParent()->getInstList().erase(I);
5509 WorkList.push_back(cast<Instruction>(NewSCC));
5516 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
5517 Value *Cond = SI.getCondition();
5518 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
5519 if (I->getOpcode() == Instruction::Add)
5520 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
5521 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
5522 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
5523 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
5525 SI.setOperand(0, I->getOperand(0));
5526 WorkList.push_back(I);
5534 void InstCombiner::removeFromWorkList(Instruction *I) {
5535 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
5540 /// TryToSinkInstruction - Try to move the specified instruction from its
5541 /// current block into the beginning of DestBlock, which can only happen if it's
5542 /// safe to move the instruction past all of the instructions between it and the
5543 /// end of its block.
5544 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
5545 assert(I->hasOneUse() && "Invariants didn't hold!");
5547 // Cannot move control-flow-involving instructions.
5548 if (isa<PHINode>(I) || isa<InvokeInst>(I) || isa<CallInst>(I)) return false;
5550 // Do not sink alloca instructions out of the entry block.
5551 if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front())
5554 // We can only sink load instructions if there is nothing between the load and
5555 // the end of block that could change the value.
5556 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
5557 if (LI->isVolatile()) return false; // Don't sink volatile loads.
5559 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
5561 if (Scan->mayWriteToMemory())
5565 BasicBlock::iterator InsertPos = DestBlock->begin();
5566 while (isa<PHINode>(InsertPos)) ++InsertPos;
5568 I->moveBefore(InsertPos);
5573 bool InstCombiner::runOnFunction(Function &F) {
5574 bool Changed = false;
5575 TD = &getAnalysis<TargetData>();
5578 // Populate the worklist with the reachable instructions.
5579 std::set<BasicBlock*> Visited;
5580 for (df_ext_iterator<BasicBlock*> BB = df_ext_begin(&F.front(), Visited),
5581 E = df_ext_end(&F.front(), Visited); BB != E; ++BB)
5582 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
5583 WorkList.push_back(I);
5585 // Do a quick scan over the function. If we find any blocks that are
5586 // unreachable, remove any instructions inside of them. This prevents
5587 // the instcombine code from having to deal with some bad special cases.
5588 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
5589 if (!Visited.count(BB)) {
5590 Instruction *Term = BB->getTerminator();
5591 while (Term != BB->begin()) { // Remove instrs bottom-up
5592 BasicBlock::iterator I = Term; --I;
5594 DEBUG(std::cerr << "IC: DCE: " << *I);
5597 if (!I->use_empty())
5598 I->replaceAllUsesWith(UndefValue::get(I->getType()));
5599 I->eraseFromParent();
5604 while (!WorkList.empty()) {
5605 Instruction *I = WorkList.back(); // Get an instruction from the worklist
5606 WorkList.pop_back();
5608 // Check to see if we can DCE or ConstantPropagate the instruction...
5609 // Check to see if we can DIE the instruction...
5610 if (isInstructionTriviallyDead(I)) {
5611 // Add operands to the worklist...
5612 if (I->getNumOperands() < 4)
5613 AddUsesToWorkList(*I);
5616 DEBUG(std::cerr << "IC: DCE: " << *I);
5618 I->eraseFromParent();
5619 removeFromWorkList(I);
5623 // Instruction isn't dead, see if we can constant propagate it...
5624 if (Constant *C = ConstantFoldInstruction(I)) {
5625 Value* Ptr = I->getOperand(0);
5626 if (isa<GetElementPtrInst>(I) &&
5627 cast<Constant>(Ptr)->isNullValue() &&
5628 !isa<ConstantPointerNull>(C) &&
5629 cast<PointerType>(Ptr->getType())->getElementType()->isSized()) {
5630 // If this is a constant expr gep that is effectively computing an
5631 // "offsetof", fold it into 'cast int X to T*' instead of 'gep 0, 0, 12'
5632 bool isFoldableGEP = true;
5633 for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
5634 if (!isa<ConstantInt>(I->getOperand(i)))
5635 isFoldableGEP = false;
5636 if (isFoldableGEP) {
5637 uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
5638 std::vector<Value*>(I->op_begin()+1, I->op_end()));
5639 C = ConstantUInt::get(Type::ULongTy, Offset);
5640 C = ConstantExpr::getCast(C, TD->getIntPtrType());
5641 C = ConstantExpr::getCast(C, I->getType());
5645 DEBUG(std::cerr << "IC: ConstFold to: " << *C << " from: " << *I);
5647 // Add operands to the worklist...
5648 AddUsesToWorkList(*I);
5649 ReplaceInstUsesWith(*I, C);
5652 I->getParent()->getInstList().erase(I);
5653 removeFromWorkList(I);
5657 // See if we can trivially sink this instruction to a successor basic block.
5658 if (I->hasOneUse()) {
5659 BasicBlock *BB = I->getParent();
5660 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
5661 if (UserParent != BB) {
5662 bool UserIsSuccessor = false;
5663 // See if the user is one of our successors.
5664 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
5665 if (*SI == UserParent) {
5666 UserIsSuccessor = true;
5670 // If the user is one of our immediate successors, and if that successor
5671 // only has us as a predecessors (we'd have to split the critical edge
5672 // otherwise), we can keep going.
5673 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
5674 next(pred_begin(UserParent)) == pred_end(UserParent))
5675 // Okay, the CFG is simple enough, try to sink this instruction.
5676 Changed |= TryToSinkInstruction(I, UserParent);
5680 // Now that we have an instruction, try combining it to simplify it...
5681 if (Instruction *Result = visit(*I)) {
5683 // Should we replace the old instruction with a new one?
5685 DEBUG(std::cerr << "IC: Old = " << *I
5686 << " New = " << *Result);
5688 // Everything uses the new instruction now.
5689 I->replaceAllUsesWith(Result);
5691 // Push the new instruction and any users onto the worklist.
5692 WorkList.push_back(Result);
5693 AddUsersToWorkList(*Result);
5695 // Move the name to the new instruction first...
5696 std::string OldName = I->getName(); I->setName("");
5697 Result->setName(OldName);
5699 // Insert the new instruction into the basic block...
5700 BasicBlock *InstParent = I->getParent();
5701 BasicBlock::iterator InsertPos = I;
5703 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
5704 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
5707 InstParent->getInstList().insert(InsertPos, Result);
5709 // Make sure that we reprocess all operands now that we reduced their
5711 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
5712 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
5713 WorkList.push_back(OpI);
5715 // Instructions can end up on the worklist more than once. Make sure
5716 // we do not process an instruction that has been deleted.
5717 removeFromWorkList(I);
5719 // Erase the old instruction.
5720 InstParent->getInstList().erase(I);
5722 DEBUG(std::cerr << "IC: MOD = " << *I);
5724 // If the instruction was modified, it's possible that it is now dead.
5725 // if so, remove it.
5726 if (isInstructionTriviallyDead(I)) {
5727 // Make sure we process all operands now that we are reducing their
5729 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
5730 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
5731 WorkList.push_back(OpI);
5733 // Instructions may end up in the worklist more than once. Erase all
5734 // occurrances of this instruction.
5735 removeFromWorkList(I);
5736 I->eraseFromParent();
5738 WorkList.push_back(Result);
5739 AddUsersToWorkList(*Result);
5749 FunctionPass *llvm::createInstructionCombiningPass() {
5750 return new InstCombiner();