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/PatternMatch.h"
50 #include "llvm/ADT/DepthFirstIterator.h"
51 #include "llvm/ADT/Statistic.h"
52 #include "llvm/ADT/STLExtras.h"
55 using namespace llvm::PatternMatch;
58 Statistic<> NumCombined ("instcombine", "Number of insts combined");
59 Statistic<> NumConstProp("instcombine", "Number of constant folds");
60 Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
61 Statistic<> NumSunkInst ("instcombine", "Number of instructions sunk");
63 class InstCombiner : public FunctionPass,
64 public InstVisitor<InstCombiner, Instruction*> {
65 // Worklist of all of the instructions that need to be simplified.
66 std::vector<Instruction*> WorkList;
69 /// AddUsersToWorkList - When an instruction is simplified, add all users of
70 /// the instruction to the work lists because they might get more simplified
73 void AddUsersToWorkList(Instruction &I) {
74 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
76 WorkList.push_back(cast<Instruction>(*UI));
79 /// AddUsesToWorkList - When an instruction is simplified, add operands to
80 /// the work lists because they might get more simplified now.
82 void AddUsesToWorkList(Instruction &I) {
83 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
84 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
85 WorkList.push_back(Op);
88 // removeFromWorkList - remove all instances of I from the worklist.
89 void removeFromWorkList(Instruction *I);
91 virtual bool runOnFunction(Function &F);
93 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
94 AU.addRequired<TargetData>();
98 TargetData &getTargetData() const { return *TD; }
100 // Visitation implementation - Implement instruction combining for different
101 // instruction types. The semantics are as follows:
103 // null - No change was made
104 // I - Change was made, I is still valid, I may be dead though
105 // otherwise - Change was made, replace I with returned instruction
107 Instruction *visitAdd(BinaryOperator &I);
108 Instruction *visitSub(BinaryOperator &I);
109 Instruction *visitMul(BinaryOperator &I);
110 Instruction *visitDiv(BinaryOperator &I);
111 Instruction *visitRem(BinaryOperator &I);
112 Instruction *visitAnd(BinaryOperator &I);
113 Instruction *visitOr (BinaryOperator &I);
114 Instruction *visitXor(BinaryOperator &I);
115 Instruction *visitSetCondInst(SetCondInst &I);
116 Instruction *visitSetCondInstWithCastAndCast(SetCondInst &SCI);
118 Instruction *FoldGEPSetCC(User *GEPLHS, Value *RHS,
119 Instruction::BinaryOps Cond, Instruction &I);
120 Instruction *visitShiftInst(ShiftInst &I);
121 Instruction *visitCastInst(CastInst &CI);
122 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
124 Instruction *visitSelectInst(SelectInst &CI);
125 Instruction *visitCallInst(CallInst &CI);
126 Instruction *visitInvokeInst(InvokeInst &II);
127 Instruction *visitPHINode(PHINode &PN);
128 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
129 Instruction *visitAllocationInst(AllocationInst &AI);
130 Instruction *visitFreeInst(FreeInst &FI);
131 Instruction *visitLoadInst(LoadInst &LI);
132 Instruction *visitStoreInst(StoreInst &SI);
133 Instruction *visitBranchInst(BranchInst &BI);
134 Instruction *visitSwitchInst(SwitchInst &SI);
136 // visitInstruction - Specify what to return for unhandled instructions...
137 Instruction *visitInstruction(Instruction &I) { return 0; }
140 Instruction *visitCallSite(CallSite CS);
141 bool transformConstExprCastCall(CallSite CS);
144 // InsertNewInstBefore - insert an instruction New before instruction Old
145 // in the program. Add the new instruction to the worklist.
147 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
148 assert(New && New->getParent() == 0 &&
149 "New instruction already inserted into a basic block!");
150 BasicBlock *BB = Old.getParent();
151 BB->getInstList().insert(&Old, New); // Insert inst
152 WorkList.push_back(New); // Add to worklist
156 /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
157 /// This also adds the cast to the worklist. Finally, this returns the
159 Value *InsertCastBefore(Value *V, const Type *Ty, Instruction &Pos) {
160 if (V->getType() == Ty) return V;
162 Instruction *C = new CastInst(V, Ty, V->getName(), &Pos);
163 WorkList.push_back(C);
167 // ReplaceInstUsesWith - This method is to be used when an instruction is
168 // found to be dead, replacable with another preexisting expression. Here
169 // we add all uses of I to the worklist, replace all uses of I with the new
170 // value, then return I, so that the inst combiner will know that I was
173 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
174 AddUsersToWorkList(I); // Add all modified instrs to worklist
176 I.replaceAllUsesWith(V);
179 // If we are replacing the instruction with itself, this must be in a
180 // segment of unreachable code, so just clobber the instruction.
181 I.replaceAllUsesWith(UndefValue::get(I.getType()));
186 // EraseInstFromFunction - When dealing with an instruction that has side
187 // effects or produces a void value, we can't rely on DCE to delete the
188 // instruction. Instead, visit methods should return the value returned by
190 Instruction *EraseInstFromFunction(Instruction &I) {
191 assert(I.use_empty() && "Cannot erase instruction that is used!");
192 AddUsesToWorkList(I);
193 removeFromWorkList(&I);
195 return 0; // Don't do anything with FI
200 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
201 /// InsertBefore instruction. This is specialized a bit to avoid inserting
202 /// casts that are known to not do anything...
204 Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
205 Instruction *InsertBefore);
207 // SimplifyCommutative - This performs a few simplifications for commutative
209 bool SimplifyCommutative(BinaryOperator &I);
212 // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
213 // PHI node as operand #0, see if we can fold the instruction into the PHI
214 // (which is only possible if all operands to the PHI are constants).
215 Instruction *FoldOpIntoPhi(Instruction &I);
217 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
218 // operator and they all are only used by the PHI, PHI together their
219 // inputs, and do the operation once, to the result of the PHI.
220 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
222 Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
223 ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
225 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
226 bool Inside, Instruction &IB);
229 RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
232 // getComplexity: Assign a complexity or rank value to LLVM Values...
233 // 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
234 static unsigned getComplexity(Value *V) {
235 if (isa<Instruction>(V)) {
236 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
240 if (isa<Argument>(V)) return 3;
241 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
244 // isOnlyUse - Return true if this instruction will be deleted if we stop using
246 static bool isOnlyUse(Value *V) {
247 return V->hasOneUse() || isa<Constant>(V);
250 // getPromotedType - Return the specified type promoted as it would be to pass
251 // though a va_arg area...
252 static const Type *getPromotedType(const Type *Ty) {
253 switch (Ty->getTypeID()) {
254 case Type::SByteTyID:
255 case Type::ShortTyID: return Type::IntTy;
256 case Type::UByteTyID:
257 case Type::UShortTyID: return Type::UIntTy;
258 case Type::FloatTyID: return Type::DoubleTy;
263 // SimplifyCommutative - This performs a few simplifications for commutative
266 // 1. Order operands such that they are listed from right (least complex) to
267 // left (most complex). This puts constants before unary operators before
270 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
271 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
273 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
274 bool Changed = false;
275 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
276 Changed = !I.swapOperands();
278 if (!I.isAssociative()) return Changed;
279 Instruction::BinaryOps Opcode = I.getOpcode();
280 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
281 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
282 if (isa<Constant>(I.getOperand(1))) {
283 Constant *Folded = ConstantExpr::get(I.getOpcode(),
284 cast<Constant>(I.getOperand(1)),
285 cast<Constant>(Op->getOperand(1)));
286 I.setOperand(0, Op->getOperand(0));
287 I.setOperand(1, Folded);
289 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
290 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
291 isOnlyUse(Op) && isOnlyUse(Op1)) {
292 Constant *C1 = cast<Constant>(Op->getOperand(1));
293 Constant *C2 = cast<Constant>(Op1->getOperand(1));
295 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
296 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
297 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
300 WorkList.push_back(New);
301 I.setOperand(0, New);
302 I.setOperand(1, Folded);
309 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
310 // if the LHS is a constant zero (which is the 'negate' form).
312 static inline Value *dyn_castNegVal(Value *V) {
313 if (BinaryOperator::isNeg(V))
314 return BinaryOperator::getNegArgument(V);
316 // Constants can be considered to be negated values if they can be folded.
317 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
318 return ConstantExpr::getNeg(C);
322 static inline Value *dyn_castNotVal(Value *V) {
323 if (BinaryOperator::isNot(V))
324 return BinaryOperator::getNotArgument(V);
326 // Constants can be considered to be not'ed values...
327 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
328 return ConstantExpr::getNot(C);
332 // dyn_castFoldableMul - If this value is a multiply that can be folded into
333 // other computations (because it has a constant operand), return the
334 // non-constant operand of the multiply, and set CST to point to the multiplier.
335 // Otherwise, return null.
337 static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
338 if (V->hasOneUse() && V->getType()->isInteger())
339 if (Instruction *I = dyn_cast<Instruction>(V)) {
340 if (I->getOpcode() == Instruction::Mul)
341 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
342 return I->getOperand(0);
343 if (I->getOpcode() == Instruction::Shl)
344 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
345 // The multiplier is really 1 << CST.
346 Constant *One = ConstantInt::get(V->getType(), 1);
347 CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
348 return I->getOperand(0);
354 /// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
355 /// expression, return it.
356 static User *dyn_castGetElementPtr(Value *V) {
357 if (isa<GetElementPtrInst>(V)) return cast<User>(V);
358 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
359 if (CE->getOpcode() == Instruction::GetElementPtr)
360 return cast<User>(V);
364 // Log2 - Calculate the log base 2 for the specified value if it is exactly a
366 static unsigned Log2(uint64_t Val) {
367 assert(Val > 1 && "Values 0 and 1 should be handled elsewhere!");
370 if (Val & 1) return 0; // Multiple bits set?
377 // AddOne, SubOne - Add or subtract a constant one from an integer constant...
378 static ConstantInt *AddOne(ConstantInt *C) {
379 return cast<ConstantInt>(ConstantExpr::getAdd(C,
380 ConstantInt::get(C->getType(), 1)));
382 static ConstantInt *SubOne(ConstantInt *C) {
383 return cast<ConstantInt>(ConstantExpr::getSub(C,
384 ConstantInt::get(C->getType(), 1)));
387 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
388 // true when both operands are equal...
390 static bool isTrueWhenEqual(Instruction &I) {
391 return I.getOpcode() == Instruction::SetEQ ||
392 I.getOpcode() == Instruction::SetGE ||
393 I.getOpcode() == Instruction::SetLE;
396 /// AssociativeOpt - Perform an optimization on an associative operator. This
397 /// function is designed to check a chain of associative operators for a
398 /// potential to apply a certain optimization. Since the optimization may be
399 /// applicable if the expression was reassociated, this checks the chain, then
400 /// reassociates the expression as necessary to expose the optimization
401 /// opportunity. This makes use of a special Functor, which must define
402 /// 'shouldApply' and 'apply' methods.
404 template<typename Functor>
405 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
406 unsigned Opcode = Root.getOpcode();
407 Value *LHS = Root.getOperand(0);
409 // Quick check, see if the immediate LHS matches...
410 if (F.shouldApply(LHS))
411 return F.apply(Root);
413 // Otherwise, if the LHS is not of the same opcode as the root, return.
414 Instruction *LHSI = dyn_cast<Instruction>(LHS);
415 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
416 // Should we apply this transform to the RHS?
417 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
419 // If not to the RHS, check to see if we should apply to the LHS...
420 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
421 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
425 // If the functor wants to apply the optimization to the RHS of LHSI,
426 // reassociate the expression from ((? op A) op B) to (? op (A op B))
428 BasicBlock *BB = Root.getParent();
430 // Now all of the instructions are in the current basic block, go ahead
431 // and perform the reassociation.
432 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
434 // First move the selected RHS to the LHS of the root...
435 Root.setOperand(0, LHSI->getOperand(1));
437 // Make what used to be the LHS of the root be the user of the root...
438 Value *ExtraOperand = TmpLHSI->getOperand(1);
439 if (&Root == TmpLHSI) {
440 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
443 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
444 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
445 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
446 BasicBlock::iterator ARI = &Root; ++ARI;
447 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
450 // Now propagate the ExtraOperand down the chain of instructions until we
452 while (TmpLHSI != LHSI) {
453 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
454 // Move the instruction to immediately before the chain we are
455 // constructing to avoid breaking dominance properties.
456 NextLHSI->getParent()->getInstList().remove(NextLHSI);
457 BB->getInstList().insert(ARI, NextLHSI);
460 Value *NextOp = NextLHSI->getOperand(1);
461 NextLHSI->setOperand(1, ExtraOperand);
463 ExtraOperand = NextOp;
466 // Now that the instructions are reassociated, have the functor perform
467 // the transformation...
468 return F.apply(Root);
471 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
477 // AddRHS - Implements: X + X --> X << 1
480 AddRHS(Value *rhs) : RHS(rhs) {}
481 bool shouldApply(Value *LHS) const { return LHS == RHS; }
482 Instruction *apply(BinaryOperator &Add) const {
483 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
484 ConstantInt::get(Type::UByteTy, 1));
488 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
490 struct AddMaskingAnd {
492 AddMaskingAnd(Constant *c) : C2(c) {}
493 bool shouldApply(Value *LHS) const {
495 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
496 ConstantExpr::getAnd(C1, C2)->isNullValue();
498 Instruction *apply(BinaryOperator &Add) const {
499 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
503 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
505 if (isa<CastInst>(I)) {
506 if (Constant *SOC = dyn_cast<Constant>(SO))
507 return ConstantExpr::getCast(SOC, I.getType());
509 return IC->InsertNewInstBefore(new CastInst(SO, I.getType(),
510 SO->getName() + ".cast"), I);
513 // Figure out if the constant is the left or the right argument.
514 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
515 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
517 if (Constant *SOC = dyn_cast<Constant>(SO)) {
519 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
520 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
523 Value *Op0 = SO, *Op1 = ConstOperand;
527 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
528 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
529 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&I))
530 New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh");
532 assert(0 && "Unknown binary instruction type!");
535 return IC->InsertNewInstBefore(New, I);
538 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
539 // constant as the other operand, try to fold the binary operator into the
540 // select arguments. This also works for Cast instructions, which obviously do
541 // not have a second operand.
542 static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
544 // Don't modify shared select instructions
545 if (!SI->hasOneUse()) return 0;
546 Value *TV = SI->getOperand(1);
547 Value *FV = SI->getOperand(2);
549 if (isa<Constant>(TV) || isa<Constant>(FV)) {
550 // Bool selects with constant operands can be folded to logical ops.
551 if (SI->getType() == Type::BoolTy) return 0;
553 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
554 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
556 return new SelectInst(SI->getCondition(), SelectTrueVal,
563 /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
564 /// node as operand #0, see if we can fold the instruction into the PHI (which
565 /// is only possible if all operands to the PHI are constants).
566 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
567 PHINode *PN = cast<PHINode>(I.getOperand(0));
568 unsigned NumPHIValues = PN->getNumIncomingValues();
569 if (!PN->hasOneUse() || NumPHIValues == 0 ||
570 !isa<Constant>(PN->getIncomingValue(0))) return 0;
572 // Check to see if all of the operands of the PHI are constants. If not, we
573 // cannot do the transformation.
574 for (unsigned i = 1; i != NumPHIValues; ++i)
575 if (!isa<Constant>(PN->getIncomingValue(i)))
578 // Okay, we can do the transformation: create the new PHI node.
579 PHINode *NewPN = new PHINode(I.getType(), I.getName());
581 NewPN->reserveOperandSpace(PN->getNumOperands()/2);
582 InsertNewInstBefore(NewPN, *PN);
584 // Next, add all of the operands to the PHI.
585 if (I.getNumOperands() == 2) {
586 Constant *C = cast<Constant>(I.getOperand(1));
587 for (unsigned i = 0; i != NumPHIValues; ++i) {
588 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
589 NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
590 PN->getIncomingBlock(i));
593 assert(isa<CastInst>(I) && "Unary op should be a cast!");
594 const Type *RetTy = I.getType();
595 for (unsigned i = 0; i != NumPHIValues; ++i) {
596 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
597 NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
598 PN->getIncomingBlock(i));
601 return ReplaceInstUsesWith(I, NewPN);
604 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
605 bool Changed = SimplifyCommutative(I);
606 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
608 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
609 // X + undef -> undef
610 if (isa<UndefValue>(RHS))
611 return ReplaceInstUsesWith(I, RHS);
614 if (!I.getType()->isFloatingPoint() && // -0 + +0 = +0, so it's not a noop
616 return ReplaceInstUsesWith(I, LHS);
618 // X + (signbit) --> X ^ signbit
619 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
620 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
621 uint64_t Val = CI->getRawValue() & (1ULL << NumBits)-1;
622 if (Val == (1ULL << (NumBits-1)))
623 return BinaryOperator::createXor(LHS, RHS);
626 if (isa<PHINode>(LHS))
627 if (Instruction *NV = FoldOpIntoPhi(I))
632 if (I.getType()->isInteger()) {
633 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
635 if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
636 if (RHSI->getOpcode() == Instruction::Sub)
637 if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
638 return ReplaceInstUsesWith(I, RHSI->getOperand(0));
640 if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
641 if (LHSI->getOpcode() == Instruction::Sub)
642 if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
643 return ReplaceInstUsesWith(I, LHSI->getOperand(0));
648 if (Value *V = dyn_castNegVal(LHS))
649 return BinaryOperator::createSub(RHS, V);
652 if (!isa<Constant>(RHS))
653 if (Value *V = dyn_castNegVal(RHS))
654 return BinaryOperator::createSub(LHS, V);
658 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
659 if (X == RHS) // X*C + X --> X * (C+1)
660 return BinaryOperator::createMul(RHS, AddOne(C2));
662 // X*C1 + X*C2 --> X * (C1+C2)
664 if (X == dyn_castFoldableMul(RHS, C1))
665 return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2));
668 // X + X*C --> X * (C+1)
669 if (dyn_castFoldableMul(RHS, C2) == LHS)
670 return BinaryOperator::createMul(LHS, AddOne(C2));
673 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
674 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
675 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
677 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
679 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
680 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
681 return BinaryOperator::createSub(C, X);
684 // (X & FF00) + xx00 -> (X+xx00) & FF00
685 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
686 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
688 // See if all bits from the first bit set in the Add RHS up are included
689 // in the mask. First, get the rightmost bit.
690 uint64_t AddRHSV = CRHS->getRawValue();
692 // Form a mask of all bits from the lowest bit added through the top.
693 uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
694 AddRHSHighBits &= ~0ULL >> (64-C2->getType()->getPrimitiveSizeInBits());
696 // See if the and mask includes all of these bits.
697 uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue();
699 if (AddRHSHighBits == AddRHSHighBitsAnd) {
700 // Okay, the xform is safe. Insert the new add pronto.
701 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
703 return BinaryOperator::createAnd(NewAdd, C2);
708 // Try to fold constant add into select arguments.
709 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
710 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
714 return Changed ? &I : 0;
717 // isSignBit - Return true if the value represented by the constant only has the
718 // highest order bit set.
719 static bool isSignBit(ConstantInt *CI) {
720 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
721 return (CI->getRawValue() & (~0ULL >> (64-NumBits))) == (1ULL << (NumBits-1));
724 /// RemoveNoopCast - Strip off nonconverting casts from the value.
726 static Value *RemoveNoopCast(Value *V) {
727 if (CastInst *CI = dyn_cast<CastInst>(V)) {
728 const Type *CTy = CI->getType();
729 const Type *OpTy = CI->getOperand(0)->getType();
730 if (CTy->isInteger() && OpTy->isInteger()) {
731 if (CTy->getPrimitiveSizeInBits() == OpTy->getPrimitiveSizeInBits())
732 return RemoveNoopCast(CI->getOperand(0));
733 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
734 return RemoveNoopCast(CI->getOperand(0));
739 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
740 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
742 if (Op0 == Op1) // sub X, X -> 0
743 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
745 // If this is a 'B = x-(-A)', change to B = x+A...
746 if (Value *V = dyn_castNegVal(Op1))
747 return BinaryOperator::createAdd(Op0, V);
749 if (isa<UndefValue>(Op0))
750 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
751 if (isa<UndefValue>(Op1))
752 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
754 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
755 // Replace (-1 - A) with (~A)...
756 if (C->isAllOnesValue())
757 return BinaryOperator::createNot(Op1);
759 // C - ~X == X + (1+C)
761 if (match(Op1, m_Not(m_Value(X))))
762 return BinaryOperator::createAdd(X,
763 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
764 // -((uint)X >> 31) -> ((int)X >> 31)
765 // -((int)X >> 31) -> ((uint)X >> 31)
766 if (C->isNullValue()) {
767 Value *NoopCastedRHS = RemoveNoopCast(Op1);
768 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
769 if (SI->getOpcode() == Instruction::Shr)
770 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
772 if (SI->getType()->isSigned())
773 NewTy = SI->getType()->getUnsignedVersion();
775 NewTy = SI->getType()->getSignedVersion();
776 // Check to see if we are shifting out everything but the sign bit.
777 if (CU->getValue() == SI->getType()->getPrimitiveSizeInBits()-1) {
778 // Ok, the transformation is safe. Insert a cast of the incoming
779 // value, then the new shift, then the new cast.
780 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
781 SI->getOperand(0)->getName());
782 Value *InV = InsertNewInstBefore(FirstCast, I);
783 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
785 if (NewShift->getType() == I.getType())
788 InV = InsertNewInstBefore(NewShift, I);
789 return new CastInst(NewShift, I.getType());
795 // Try to fold constant sub into select arguments.
796 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
797 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
800 if (isa<PHINode>(Op0))
801 if (Instruction *NV = FoldOpIntoPhi(I))
805 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
806 if (Op1I->getOpcode() == Instruction::Add &&
807 !Op0->getType()->isFloatingPoint()) {
808 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
809 return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
810 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
811 return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
812 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
813 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
814 // C1-(X+C2) --> (C1-C2)-X
815 return BinaryOperator::createSub(ConstantExpr::getSub(CI1, CI2),
816 Op1I->getOperand(0));
820 if (Op1I->hasOneUse()) {
821 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
822 // is not used by anyone else...
824 if (Op1I->getOpcode() == Instruction::Sub &&
825 !Op1I->getType()->isFloatingPoint()) {
826 // Swap the two operands of the subexpr...
827 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
828 Op1I->setOperand(0, IIOp1);
829 Op1I->setOperand(1, IIOp0);
831 // Create the new top level add instruction...
832 return BinaryOperator::createAdd(Op0, Op1);
835 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
837 if (Op1I->getOpcode() == Instruction::And &&
838 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
839 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
842 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
843 return BinaryOperator::createAnd(Op0, NewNot);
846 // -(X sdiv C) -> (X sdiv -C)
847 if (Op1I->getOpcode() == Instruction::Div)
848 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
849 if (CSI->isNullValue())
850 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
851 return BinaryOperator::createDiv(Op1I->getOperand(0),
852 ConstantExpr::getNeg(DivRHS));
854 // X - X*C --> X * (1-C)
856 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
858 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
859 return BinaryOperator::createMul(Op0, CP1);
864 if (!Op0->getType()->isFloatingPoint())
865 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
866 if (Op0I->getOpcode() == Instruction::Add) {
867 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
868 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
869 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
870 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
871 } else if (Op0I->getOpcode() == Instruction::Sub) {
872 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
873 return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName());
877 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
878 if (X == Op1) { // X*C - X --> X * (C-1)
879 Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
880 return BinaryOperator::createMul(Op1, CP1);
883 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
884 if (X == dyn_castFoldableMul(Op1, C2))
885 return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
890 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
891 /// really just returns true if the most significant (sign) bit is set.
892 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
893 if (RHS->getType()->isSigned()) {
894 // True if source is LHS < 0 or LHS <= -1
895 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
896 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
898 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
899 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
900 // the size of the integer type.
901 if (Opcode == Instruction::SetGE)
902 return RHSC->getValue() ==
903 1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1);
904 if (Opcode == Instruction::SetGT)
905 return RHSC->getValue() ==
906 (1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1))-1;
911 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
912 bool Changed = SimplifyCommutative(I);
913 Value *Op0 = I.getOperand(0);
915 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
916 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
918 // Simplify mul instructions with a constant RHS...
919 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
920 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
922 // ((X << C1)*C2) == (X * (C2 << C1))
923 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
924 if (SI->getOpcode() == Instruction::Shl)
925 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
926 return BinaryOperator::createMul(SI->getOperand(0),
927 ConstantExpr::getShl(CI, ShOp));
929 if (CI->isNullValue())
930 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
931 if (CI->equalsInt(1)) // X * 1 == X
932 return ReplaceInstUsesWith(I, Op0);
933 if (CI->isAllOnesValue()) // X * -1 == 0 - X
934 return BinaryOperator::createNeg(Op0, I.getName());
936 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
937 if (uint64_t C = Log2(Val)) // Replace X*(2^C) with X << C
938 return new ShiftInst(Instruction::Shl, Op0,
939 ConstantUInt::get(Type::UByteTy, C));
940 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
941 if (Op1F->isNullValue())
942 return ReplaceInstUsesWith(I, Op1);
944 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
945 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
946 if (Op1F->getValue() == 1.0)
947 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
950 // Try to fold constant mul into select arguments.
951 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
952 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
955 if (isa<PHINode>(Op0))
956 if (Instruction *NV = FoldOpIntoPhi(I))
960 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
961 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
962 return BinaryOperator::createMul(Op0v, Op1v);
964 // If one of the operands of the multiply is a cast from a boolean value, then
965 // we know the bool is either zero or one, so this is a 'masking' multiply.
966 // See if we can simplify things based on how the boolean was originally
968 CastInst *BoolCast = 0;
969 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
970 if (CI->getOperand(0)->getType() == Type::BoolTy)
973 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
974 if (CI->getOperand(0)->getType() == Type::BoolTy)
977 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
978 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
979 const Type *SCOpTy = SCIOp0->getType();
981 // If the setcc is true iff the sign bit of X is set, then convert this
982 // multiply into a shift/and combination.
983 if (isa<ConstantInt>(SCIOp1) &&
984 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
985 // Shift the X value right to turn it into "all signbits".
986 Constant *Amt = ConstantUInt::get(Type::UByteTy,
987 SCOpTy->getPrimitiveSizeInBits()-1);
988 if (SCIOp0->getType()->isUnsigned()) {
989 const Type *NewTy = SCIOp0->getType()->getSignedVersion();
990 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
991 SCIOp0->getName()), I);
995 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
996 BoolCast->getOperand(0)->getName()+
999 // If the multiply type is not the same as the source type, sign extend
1000 // or truncate to the multiply type.
1001 if (I.getType() != V->getType())
1002 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
1004 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
1005 return BinaryOperator::createAnd(V, OtherOp);
1010 return Changed ? &I : 0;
1013 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
1014 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1016 if (isa<UndefValue>(Op0)) // undef / X -> 0
1017 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1018 if (isa<UndefValue>(Op1))
1019 return ReplaceInstUsesWith(I, Op1); // X / undef -> undef
1021 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1023 if (RHS->equalsInt(1))
1024 return ReplaceInstUsesWith(I, Op0);
1027 if (RHS->isAllOnesValue())
1028 return BinaryOperator::createNeg(Op0);
1030 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
1031 if (LHS->getOpcode() == Instruction::Div)
1032 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
1033 // (X / C1) / C2 -> X / (C1*C2)
1034 return BinaryOperator::createDiv(LHS->getOperand(0),
1035 ConstantExpr::getMul(RHS, LHSRHS));
1038 // Check to see if this is an unsigned division with an exact power of 2,
1039 // if so, convert to a right shift.
1040 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1041 if (uint64_t Val = C->getValue()) // Don't break X / 0
1042 if (uint64_t C = Log2(Val))
1043 return new ShiftInst(Instruction::Shr, Op0,
1044 ConstantUInt::get(Type::UByteTy, C));
1047 if (RHS->getType()->isSigned())
1048 if (Value *LHSNeg = dyn_castNegVal(Op0))
1049 return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS));
1051 if (!RHS->isNullValue()) {
1052 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1053 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1055 if (isa<PHINode>(Op0))
1056 if (Instruction *NV = FoldOpIntoPhi(I))
1061 // If this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1062 // transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'.
1063 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1064 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1065 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1066 if (STO->getValue() == 0) { // Couldn't be this argument.
1067 I.setOperand(1, SFO);
1069 } else if (SFO->getValue() == 0) {
1070 I.setOperand(1, STO);
1074 uint64_t TVA = STO->getValue(), FVA = SFO->getValue();
1075 unsigned TSA = 0, FSA = 0;
1076 if ((TVA == 1 || (TSA = Log2(TVA))) && // Log2 fails for 0 & 1.
1077 (FVA == 1 || (FSA = Log2(FVA)))) {
1078 Constant *TC = ConstantUInt::get(Type::UByteTy, TSA);
1079 Instruction *TSI = new ShiftInst(Instruction::Shr, Op0,
1080 TC, SI->getName()+".t");
1081 TSI = InsertNewInstBefore(TSI, I);
1083 Constant *FC = ConstantUInt::get(Type::UByteTy, FSA);
1084 Instruction *FSI = new ShiftInst(Instruction::Shr, Op0,
1085 FC, SI->getName()+".f");
1086 FSI = InsertNewInstBefore(FSI, I);
1087 return new SelectInst(SI->getOperand(0), TSI, FSI);
1091 // 0 / X == 0, we don't need to preserve faults!
1092 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1093 if (LHS->equalsInt(0))
1094 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1100 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
1101 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1102 if (I.getType()->isSigned())
1103 if (Value *RHSNeg = dyn_castNegVal(Op1))
1104 if (!isa<ConstantSInt>(RHSNeg) ||
1105 cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
1107 AddUsesToWorkList(I);
1108 I.setOperand(1, RHSNeg);
1112 if (isa<UndefValue>(Op0)) // undef % X -> 0
1113 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1114 if (isa<UndefValue>(Op1))
1115 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
1117 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1118 if (RHS->equalsInt(1)) // X % 1 == 0
1119 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1121 // Check to see if this is an unsigned remainder with an exact power of 2,
1122 // if so, convert to a bitwise and.
1123 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1124 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
1125 if (!(Val & (Val-1))) // Power of 2
1126 return BinaryOperator::createAnd(Op0,
1127 ConstantUInt::get(I.getType(), Val-1));
1129 if (!RHS->isNullValue()) {
1130 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1131 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1133 if (isa<PHINode>(Op0))
1134 if (Instruction *NV = FoldOpIntoPhi(I))
1139 // If this is 'urem X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1140 // transform this into: '(Cond ? (urem X, C1) : (urem X, C2))'.
1141 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1142 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1143 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1144 if (STO->getValue() == 0) { // Couldn't be this argument.
1145 I.setOperand(1, SFO);
1147 } else if (SFO->getValue() == 0) {
1148 I.setOperand(1, STO);
1152 if (!(STO->getValue() & (STO->getValue()-1)) &&
1153 !(SFO->getValue() & (SFO->getValue()-1))) {
1154 Value *TrueAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1155 SubOne(STO), SI->getName()+".t"), I);
1156 Value *FalseAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1157 SubOne(SFO), SI->getName()+".f"), I);
1158 return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
1162 // 0 % X == 0, we don't need to preserve faults!
1163 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1164 if (LHS->equalsInt(0))
1165 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1170 // isMaxValueMinusOne - return true if this is Max-1
1171 static bool isMaxValueMinusOne(const ConstantInt *C) {
1172 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
1173 // Calculate -1 casted to the right type...
1174 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1175 uint64_t Val = ~0ULL; // All ones
1176 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1177 return CU->getValue() == Val-1;
1180 const ConstantSInt *CS = cast<ConstantSInt>(C);
1182 // Calculate 0111111111..11111
1183 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1184 int64_t Val = INT64_MAX; // All ones
1185 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1186 return CS->getValue() == Val-1;
1189 // isMinValuePlusOne - return true if this is Min+1
1190 static bool isMinValuePlusOne(const ConstantInt *C) {
1191 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1192 return CU->getValue() == 1;
1194 const ConstantSInt *CS = cast<ConstantSInt>(C);
1196 // Calculate 1111111111000000000000
1197 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1198 int64_t Val = -1; // All ones
1199 Val <<= TypeBits-1; // Shift over to the right spot
1200 return CS->getValue() == Val+1;
1203 // isOneBitSet - Return true if there is exactly one bit set in the specified
1205 static bool isOneBitSet(const ConstantInt *CI) {
1206 uint64_t V = CI->getRawValue();
1207 return V && (V & (V-1)) == 0;
1210 #if 0 // Currently unused
1211 // isLowOnes - Return true if the constant is of the form 0+1+.
1212 static bool isLowOnes(const ConstantInt *CI) {
1213 uint64_t V = CI->getRawValue();
1215 // There won't be bits set in parts that the type doesn't contain.
1216 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1218 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1219 return U && V && (U & V) == 0;
1223 // isHighOnes - Return true if the constant is of the form 1+0+.
1224 // This is the same as lowones(~X).
1225 static bool isHighOnes(const ConstantInt *CI) {
1226 uint64_t V = ~CI->getRawValue();
1228 // There won't be bits set in parts that the type doesn't contain.
1229 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1231 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1232 return U && V && (U & V) == 0;
1236 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
1237 /// are carefully arranged to allow folding of expressions such as:
1239 /// (A < B) | (A > B) --> (A != B)
1241 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
1242 /// represents that the comparison is true if A == B, and bit value '1' is true
1245 static unsigned getSetCondCode(const SetCondInst *SCI) {
1246 switch (SCI->getOpcode()) {
1248 case Instruction::SetGT: return 1;
1249 case Instruction::SetEQ: return 2;
1250 case Instruction::SetGE: return 3;
1251 case Instruction::SetLT: return 4;
1252 case Instruction::SetNE: return 5;
1253 case Instruction::SetLE: return 6;
1256 assert(0 && "Invalid SetCC opcode!");
1261 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
1262 /// opcode and two operands into either a constant true or false, or a brand new
1263 /// SetCC instruction.
1264 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
1266 case 0: return ConstantBool::False;
1267 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
1268 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
1269 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
1270 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
1271 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
1272 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
1273 case 7: return ConstantBool::True;
1274 default: assert(0 && "Illegal SetCCCode!"); return 0;
1278 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1279 struct FoldSetCCLogical {
1282 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
1283 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
1284 bool shouldApply(Value *V) const {
1285 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
1286 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
1287 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
1290 Instruction *apply(BinaryOperator &Log) const {
1291 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
1292 if (SCI->getOperand(0) != LHS) {
1293 assert(SCI->getOperand(1) == LHS);
1294 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
1297 unsigned LHSCode = getSetCondCode(SCI);
1298 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
1300 switch (Log.getOpcode()) {
1301 case Instruction::And: Code = LHSCode & RHSCode; break;
1302 case Instruction::Or: Code = LHSCode | RHSCode; break;
1303 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
1304 default: assert(0 && "Illegal logical opcode!"); return 0;
1307 Value *RV = getSetCCValue(Code, LHS, RHS);
1308 if (Instruction *I = dyn_cast<Instruction>(RV))
1310 // Otherwise, it's a constant boolean value...
1311 return IC.ReplaceInstUsesWith(Log, RV);
1316 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
1317 /// this predicate to simplify operations downstream. V and Mask are known to
1318 /// be the same type.
1319 static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask) {
1320 // Note, we cannot consider 'undef' to be "IsZero" here. The problem is that
1321 // we cannot optimize based on the assumption that it is zero without changing
1322 // to to an explicit zero. If we don't change it to zero, other code could
1323 // optimized based on the contradictory assumption that it is non-zero.
1324 // Because instcombine aggressively folds operations with undef args anyway,
1325 // this won't lose us code quality.
1326 if (Mask->isNullValue())
1328 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
1329 return ConstantExpr::getAnd(CI, Mask)->isNullValue();
1331 if (Instruction *I = dyn_cast<Instruction>(V)) {
1332 switch (I->getOpcode()) {
1333 case Instruction::And:
1334 // (X & C1) & C2 == 0 iff C1 & C2 == 0.
1335 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1)))
1336 if (ConstantExpr::getAnd(CI, Mask)->isNullValue())
1339 case Instruction::Or:
1340 // If the LHS and the RHS are MaskedValueIsZero, the result is also zero.
1341 return MaskedValueIsZero(I->getOperand(1), Mask) &&
1342 MaskedValueIsZero(I->getOperand(0), Mask);
1343 case Instruction::Select:
1344 // If the T and F values are MaskedValueIsZero, the result is also zero.
1345 return MaskedValueIsZero(I->getOperand(2), Mask) &&
1346 MaskedValueIsZero(I->getOperand(1), Mask);
1347 case Instruction::Cast: {
1348 const Type *SrcTy = I->getOperand(0)->getType();
1349 if (SrcTy == Type::BoolTy)
1350 return (Mask->getRawValue() & 1) == 0;
1352 if (SrcTy->isInteger()) {
1353 // (cast <ty> X to int) & C2 == 0 iff <ty> could not have contained C2.
1354 if (SrcTy->isUnsigned() && // Only handle zero ext.
1355 ConstantExpr::getCast(Mask, SrcTy)->isNullValue())
1358 // If this is a noop cast, recurse.
1359 if ((SrcTy->isSigned() && SrcTy->getUnsignedVersion() == I->getType())||
1360 SrcTy->getSignedVersion() == I->getType()) {
1362 ConstantExpr::getCast(Mask, I->getOperand(0)->getType());
1363 return MaskedValueIsZero(I->getOperand(0),
1364 cast<ConstantIntegral>(NewMask));
1369 case Instruction::Shl:
1370 // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
1371 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
1372 return MaskedValueIsZero(I->getOperand(0),
1373 cast<ConstantIntegral>(ConstantExpr::getUShr(Mask, SA)));
1375 case Instruction::Shr:
1376 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
1377 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
1378 if (I->getType()->isUnsigned()) {
1379 Constant *C1 = ConstantIntegral::getAllOnesValue(I->getType());
1380 C1 = ConstantExpr::getShr(C1, SA);
1381 C1 = ConstantExpr::getAnd(C1, Mask);
1382 if (C1->isNullValue())
1392 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
1393 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
1394 // guaranteed to be either a shift instruction or a binary operator.
1395 Instruction *InstCombiner::OptAndOp(Instruction *Op,
1396 ConstantIntegral *OpRHS,
1397 ConstantIntegral *AndRHS,
1398 BinaryOperator &TheAnd) {
1399 Value *X = Op->getOperand(0);
1400 Constant *Together = 0;
1401 if (!isa<ShiftInst>(Op))
1402 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
1404 switch (Op->getOpcode()) {
1405 case Instruction::Xor:
1406 if (Op->hasOneUse()) {
1407 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
1408 std::string OpName = Op->getName(); Op->setName("");
1409 Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
1410 InsertNewInstBefore(And, TheAnd);
1411 return BinaryOperator::createXor(And, Together);
1414 case Instruction::Or:
1415 if (Together == AndRHS) // (X | C) & C --> C
1416 return ReplaceInstUsesWith(TheAnd, AndRHS);
1418 if (Op->hasOneUse() && Together != OpRHS) {
1419 // (X | C1) & C2 --> (X | (C1&C2)) & C2
1420 std::string Op0Name = Op->getName(); Op->setName("");
1421 Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
1422 InsertNewInstBefore(Or, TheAnd);
1423 return BinaryOperator::createAnd(Or, AndRHS);
1426 case Instruction::Add:
1427 if (Op->hasOneUse()) {
1428 // Adding a one to a single bit bit-field should be turned into an XOR
1429 // of the bit. First thing to check is to see if this AND is with a
1430 // single bit constant.
1431 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
1433 // Clear bits that are not part of the constant.
1434 AndRHSV &= ~0ULL >> (64-AndRHS->getType()->getPrimitiveSizeInBits());
1436 // If there is only one bit set...
1437 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
1438 // Ok, at this point, we know that we are masking the result of the
1439 // ADD down to exactly one bit. If the constant we are adding has
1440 // no bits set below this bit, then we can eliminate the ADD.
1441 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
1443 // Check to see if any bits below the one bit set in AndRHSV are set.
1444 if ((AddRHS & (AndRHSV-1)) == 0) {
1445 // If not, the only thing that can effect the output of the AND is
1446 // the bit specified by AndRHSV. If that bit is set, the effect of
1447 // the XOR is to toggle the bit. If it is clear, then the ADD has
1449 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
1450 TheAnd.setOperand(0, X);
1453 std::string Name = Op->getName(); Op->setName("");
1454 // Pull the XOR out of the AND.
1455 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
1456 InsertNewInstBefore(NewAnd, TheAnd);
1457 return BinaryOperator::createXor(NewAnd, AndRHS);
1464 case Instruction::Shl: {
1465 // We know that the AND will not produce any of the bits shifted in, so if
1466 // the anded constant includes them, clear them now!
1468 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1469 Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
1470 Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
1472 if (CI == ShlMask) { // Masking out bits that the shift already masks
1473 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
1474 } else if (CI != AndRHS) { // Reducing bits set in and.
1475 TheAnd.setOperand(1, CI);
1480 case Instruction::Shr:
1481 // We know that the AND will not produce any of the bits shifted in, so if
1482 // the anded constant includes them, clear them now! This only applies to
1483 // unsigned shifts, because a signed shr may bring in set bits!
1485 if (AndRHS->getType()->isUnsigned()) {
1486 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1487 Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS);
1488 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1490 if (CI == ShrMask) { // Masking out bits that the shift already masks.
1491 return ReplaceInstUsesWith(TheAnd, Op);
1492 } else if (CI != AndRHS) {
1493 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
1496 } else { // Signed shr.
1497 // See if this is shifting in some sign extension, then masking it out
1499 if (Op->hasOneUse()) {
1500 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1501 Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS);
1502 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1503 if (CI == AndRHS) { // Masking out bits shifted in.
1504 // Make the argument unsigned.
1505 Value *ShVal = Op->getOperand(0);
1506 ShVal = InsertCastBefore(ShVal,
1507 ShVal->getType()->getUnsignedVersion(),
1509 ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal,
1510 OpRHS, Op->getName()),
1512 Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType());
1513 ShVal = InsertNewInstBefore(BinaryOperator::createAnd(ShVal, AndRHS2,
1516 return new CastInst(ShVal, Op->getType());
1526 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
1527 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
1528 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. IB is the location to
1529 /// insert new instructions.
1530 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
1531 bool Inside, Instruction &IB) {
1532 assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
1533 "Lo is not <= Hi in range emission code!");
1535 if (Lo == Hi) // Trivially false.
1536 return new SetCondInst(Instruction::SetNE, V, V);
1537 if (cast<ConstantIntegral>(Lo)->isMinValue())
1538 return new SetCondInst(Instruction::SetLT, V, Hi);
1540 Constant *AddCST = ConstantExpr::getNeg(Lo);
1541 Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
1542 InsertNewInstBefore(Add, IB);
1543 // Convert to unsigned for the comparison.
1544 const Type *UnsType = Add->getType()->getUnsignedVersion();
1545 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1546 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1547 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1548 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1551 if (Lo == Hi) // Trivially true.
1552 return new SetCondInst(Instruction::SetEQ, V, V);
1554 Hi = SubOne(cast<ConstantInt>(Hi));
1555 if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
1556 return new SetCondInst(Instruction::SetGT, V, Hi);
1558 // Emit X-Lo > Hi-Lo-1
1559 Constant *AddCST = ConstantExpr::getNeg(Lo);
1560 Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
1561 InsertNewInstBefore(Add, IB);
1562 // Convert to unsigned for the comparison.
1563 const Type *UnsType = Add->getType()->getUnsignedVersion();
1564 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1565 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1566 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1567 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1571 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1572 bool Changed = SimplifyCommutative(I);
1573 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1575 if (isa<UndefValue>(Op1)) // X & undef -> 0
1576 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1580 return ReplaceInstUsesWith(I, Op1);
1582 if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) {
1584 if (AndRHS->isAllOnesValue())
1585 return ReplaceInstUsesWith(I, Op0);
1587 if (MaskedValueIsZero(Op0, AndRHS)) // LHS & RHS == 0
1588 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1590 // If the mask is not masking out any bits, there is no reason to do the
1591 // and in the first place.
1592 ConstantIntegral *NotAndRHS =
1593 cast<ConstantIntegral>(ConstantExpr::getNot(AndRHS));
1594 if (MaskedValueIsZero(Op0, NotAndRHS))
1595 return ReplaceInstUsesWith(I, Op0);
1597 // Optimize a variety of ((val OP C1) & C2) combinations...
1598 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
1599 Instruction *Op0I = cast<Instruction>(Op0);
1600 Value *Op0LHS = Op0I->getOperand(0);
1601 Value *Op0RHS = Op0I->getOperand(1);
1602 switch (Op0I->getOpcode()) {
1603 case Instruction::Xor:
1604 case Instruction::Or:
1605 // (X ^ V) & C2 --> (X & C2) iff (V & C2) == 0
1606 // (X | V) & C2 --> (X & C2) iff (V & C2) == 0
1607 if (MaskedValueIsZero(Op0LHS, AndRHS))
1608 return BinaryOperator::createAnd(Op0RHS, AndRHS);
1609 if (MaskedValueIsZero(Op0RHS, AndRHS))
1610 return BinaryOperator::createAnd(Op0LHS, AndRHS);
1612 // If the mask is only needed on one incoming arm, push it up.
1613 if (Op0I->hasOneUse()) {
1614 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
1615 // Not masking anything out for the LHS, move to RHS.
1616 Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
1617 Op0RHS->getName()+".masked");
1618 InsertNewInstBefore(NewRHS, I);
1619 return BinaryOperator::create(
1620 cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
1622 if (!isa<Constant>(NotAndRHS) &&
1623 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
1624 // Not masking anything out for the RHS, move to LHS.
1625 Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
1626 Op0LHS->getName()+".masked");
1627 InsertNewInstBefore(NewLHS, I);
1628 return BinaryOperator::create(
1629 cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
1634 case Instruction::And:
1635 // (X & V) & C2 --> 0 iff (V & C2) == 0
1636 if (MaskedValueIsZero(Op0LHS, AndRHS) ||
1637 MaskedValueIsZero(Op0RHS, AndRHS))
1638 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1642 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1643 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
1645 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
1646 const Type *SrcTy = CI->getOperand(0)->getType();
1648 // If this is an integer sign or zero extension instruction.
1649 if (SrcTy->isIntegral() &&
1650 SrcTy->getPrimitiveSizeInBits() <
1651 CI->getType()->getPrimitiveSizeInBits()) {
1653 if (SrcTy->isUnsigned()) {
1654 // See if this and is clearing out bits that are known to be zero
1655 // anyway (due to the zero extension).
1656 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1657 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1658 Constant *Result = ConstantExpr::getAnd(Mask, AndRHS);
1659 if (Result == Mask) // The "and" isn't doing anything, remove it.
1660 return ReplaceInstUsesWith(I, CI);
1661 if (Result != AndRHS) { // Reduce the and RHS constant.
1662 I.setOperand(1, Result);
1667 if (CI->hasOneUse() && SrcTy->isInteger()) {
1668 // We can only do this if all of the sign bits brought in are masked
1669 // out. Compute this by first getting 0000011111, then inverting
1671 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1672 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1673 Mask = ConstantExpr::getNot(Mask); // 1's in the new bits.
1674 if (ConstantExpr::getAnd(Mask, AndRHS)->isNullValue()) {
1675 // If the and is clearing all of the sign bits, change this to a
1676 // zero extension cast. To do this, cast the cast input to
1677 // unsigned, then to the requested size.
1678 Value *CastOp = CI->getOperand(0);
1680 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
1681 CI->getName()+".uns");
1682 NC = InsertNewInstBefore(NC, I);
1683 // Finally, insert a replacement for CI.
1684 NC = new CastInst(NC, CI->getType(), CI->getName());
1686 NC = InsertNewInstBefore(NC, I);
1687 WorkList.push_back(CI); // Delete CI later.
1688 I.setOperand(0, NC);
1689 return &I; // The AND operand was modified.
1696 // Try to fold constant and into select arguments.
1697 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1698 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1700 if (isa<PHINode>(Op0))
1701 if (Instruction *NV = FoldOpIntoPhi(I))
1705 Value *Op0NotVal = dyn_castNotVal(Op0);
1706 Value *Op1NotVal = dyn_castNotVal(Op1);
1708 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1709 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1711 // (~A & ~B) == (~(A | B)) - De Morgan's Law
1712 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1713 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
1714 I.getName()+".demorgan");
1715 InsertNewInstBefore(Or, I);
1716 return BinaryOperator::createNot(Or);
1719 if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
1720 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1721 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1724 Value *LHSVal, *RHSVal;
1725 ConstantInt *LHSCst, *RHSCst;
1726 Instruction::BinaryOps LHSCC, RHSCC;
1727 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1728 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1729 if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
1730 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1731 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1732 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1733 // Ensure that the larger constant is on the RHS.
1734 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1735 SetCondInst *LHS = cast<SetCondInst>(Op0);
1736 if (cast<ConstantBool>(Cmp)->getValue()) {
1737 std::swap(LHS, RHS);
1738 std::swap(LHSCst, RHSCst);
1739 std::swap(LHSCC, RHSCC);
1742 // At this point, we know we have have two setcc instructions
1743 // comparing a value against two constants and and'ing the result
1744 // together. Because of the above check, we know that we only have
1745 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1746 // FoldSetCCLogical check above), that the two constants are not
1748 assert(LHSCst != RHSCst && "Compares not folded above?");
1751 default: assert(0 && "Unknown integer condition code!");
1752 case Instruction::SetEQ:
1754 default: assert(0 && "Unknown integer condition code!");
1755 case Instruction::SetEQ: // (X == 13 & X == 15) -> false
1756 case Instruction::SetGT: // (X == 13 & X > 15) -> false
1757 return ReplaceInstUsesWith(I, ConstantBool::False);
1758 case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
1759 case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
1760 return ReplaceInstUsesWith(I, LHS);
1762 case Instruction::SetNE:
1764 default: assert(0 && "Unknown integer condition code!");
1765 case Instruction::SetLT:
1766 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
1767 return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
1768 break; // (X != 13 & X < 15) -> no change
1769 case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
1770 case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
1771 return ReplaceInstUsesWith(I, RHS);
1772 case Instruction::SetNE:
1773 if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
1774 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1775 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
1776 LHSVal->getName()+".off");
1777 InsertNewInstBefore(Add, I);
1778 const Type *UnsType = Add->getType()->getUnsignedVersion();
1779 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
1780 AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
1781 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1782 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1784 break; // (X != 13 & X != 15) -> no change
1787 case Instruction::SetLT:
1789 default: assert(0 && "Unknown integer condition code!");
1790 case Instruction::SetEQ: // (X < 13 & X == 15) -> false
1791 case Instruction::SetGT: // (X < 13 & X > 15) -> false
1792 return ReplaceInstUsesWith(I, ConstantBool::False);
1793 case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
1794 case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
1795 return ReplaceInstUsesWith(I, LHS);
1797 case Instruction::SetGT:
1799 default: assert(0 && "Unknown integer condition code!");
1800 case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
1801 return ReplaceInstUsesWith(I, LHS);
1802 case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
1803 return ReplaceInstUsesWith(I, RHS);
1804 case Instruction::SetNE:
1805 if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
1806 return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
1807 break; // (X > 13 & X != 15) -> no change
1808 case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
1809 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
1815 return Changed ? &I : 0;
1818 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
1819 bool Changed = SimplifyCommutative(I);
1820 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1822 if (isa<UndefValue>(Op1))
1823 return ReplaceInstUsesWith(I, // X | undef -> -1
1824 ConstantIntegral::getAllOnesValue(I.getType()));
1826 // or X, X = X or X, 0 == X
1827 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
1828 return ReplaceInstUsesWith(I, Op0);
1831 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1832 // If X is known to only contain bits that already exist in RHS, just
1833 // replace this instruction with RHS directly.
1834 if (MaskedValueIsZero(Op0,
1835 cast<ConstantIntegral>(ConstantExpr::getNot(RHS))))
1836 return ReplaceInstUsesWith(I, RHS);
1838 ConstantInt *C1; Value *X;
1839 // (X & C1) | C2 --> (X | C2) & (C1|C2)
1840 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1841 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0->getName());
1843 InsertNewInstBefore(Or, I);
1844 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
1847 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
1848 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1849 std::string Op0Name = Op0->getName(); Op0->setName("");
1850 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
1851 InsertNewInstBefore(Or, I);
1852 return BinaryOperator::createXor(Or,
1853 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
1856 // Try to fold constant and into select arguments.
1857 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1858 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1860 if (isa<PHINode>(Op0))
1861 if (Instruction *NV = FoldOpIntoPhi(I))
1865 Value *A, *B; ConstantInt *C1, *C2;
1867 if (match(Op0, m_And(m_Value(A), m_Value(B))))
1868 if (A == Op1 || B == Op1) // (A & ?) | A --> A
1869 return ReplaceInstUsesWith(I, Op1);
1870 if (match(Op1, m_And(m_Value(A), m_Value(B))))
1871 if (A == Op0 || B == Op0) // A | (A & ?) --> A
1872 return ReplaceInstUsesWith(I, Op0);
1874 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
1875 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
1876 MaskedValueIsZero(Op1, C1)) {
1877 Instruction *NOr = BinaryOperator::createOr(A, Op1, Op0->getName());
1879 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
1882 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
1883 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
1884 MaskedValueIsZero(Op0, C1)) {
1885 Instruction *NOr = BinaryOperator::createOr(A, Op0, Op1->getName());
1887 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
1890 // (A & C1)|(A & C2) == A & (C1|C2)
1891 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
1892 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) && A == B)
1893 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
1895 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
1896 if (A == Op1) // ~A | A == -1
1897 return ReplaceInstUsesWith(I,
1898 ConstantIntegral::getAllOnesValue(I.getType()));
1902 // Note, A is still live here!
1903 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
1905 return ReplaceInstUsesWith(I,
1906 ConstantIntegral::getAllOnesValue(I.getType()));
1908 // (~A | ~B) == (~(A & B)) - De Morgan's Law
1909 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1910 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
1911 I.getName()+".demorgan"), I);
1912 return BinaryOperator::createNot(And);
1916 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
1917 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
1918 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1921 Value *LHSVal, *RHSVal;
1922 ConstantInt *LHSCst, *RHSCst;
1923 Instruction::BinaryOps LHSCC, RHSCC;
1924 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1925 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1926 if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
1927 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1928 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1929 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1930 // Ensure that the larger constant is on the RHS.
1931 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1932 SetCondInst *LHS = cast<SetCondInst>(Op0);
1933 if (cast<ConstantBool>(Cmp)->getValue()) {
1934 std::swap(LHS, RHS);
1935 std::swap(LHSCst, RHSCst);
1936 std::swap(LHSCC, RHSCC);
1939 // At this point, we know we have have two setcc instructions
1940 // comparing a value against two constants and or'ing the result
1941 // together. Because of the above check, we know that we only have
1942 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1943 // FoldSetCCLogical check above), that the two constants are not
1945 assert(LHSCst != RHSCst && "Compares not folded above?");
1948 default: assert(0 && "Unknown integer condition code!");
1949 case Instruction::SetEQ:
1951 default: assert(0 && "Unknown integer condition code!");
1952 case Instruction::SetEQ:
1953 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
1954 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1955 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
1956 LHSVal->getName()+".off");
1957 InsertNewInstBefore(Add, I);
1958 const Type *UnsType = Add->getType()->getUnsignedVersion();
1959 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
1960 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
1961 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1962 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1964 break; // (X == 13 | X == 15) -> no change
1966 case Instruction::SetGT: // (X == 13 | X > 14) -> no change
1968 case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
1969 case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
1970 return ReplaceInstUsesWith(I, RHS);
1973 case Instruction::SetNE:
1975 default: assert(0 && "Unknown integer condition code!");
1976 case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
1977 case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
1978 return ReplaceInstUsesWith(I, LHS);
1979 case Instruction::SetNE: // (X != 13 | X != 15) -> true
1980 case Instruction::SetLT: // (X != 13 | X < 15) -> true
1981 return ReplaceInstUsesWith(I, ConstantBool::True);
1984 case Instruction::SetLT:
1986 default: assert(0 && "Unknown integer condition code!");
1987 case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
1989 case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
1990 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
1991 case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
1992 case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
1993 return ReplaceInstUsesWith(I, RHS);
1996 case Instruction::SetGT:
1998 default: assert(0 && "Unknown integer condition code!");
1999 case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
2000 case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
2001 return ReplaceInstUsesWith(I, LHS);
2002 case Instruction::SetNE: // (X > 13 | X != 15) -> true
2003 case Instruction::SetLT: // (X > 13 | X < 15) -> true
2004 return ReplaceInstUsesWith(I, ConstantBool::True);
2009 return Changed ? &I : 0;
2012 // XorSelf - Implements: X ^ X --> 0
2015 XorSelf(Value *rhs) : RHS(rhs) {}
2016 bool shouldApply(Value *LHS) const { return LHS == RHS; }
2017 Instruction *apply(BinaryOperator &Xor) const {
2023 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
2024 bool Changed = SimplifyCommutative(I);
2025 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2027 if (isa<UndefValue>(Op1))
2028 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
2030 // xor X, X = 0, even if X is nested in a sequence of Xor's.
2031 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
2032 assert(Result == &I && "AssociativeOpt didn't work?");
2033 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2036 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2038 if (RHS->isNullValue())
2039 return ReplaceInstUsesWith(I, Op0);
2041 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2042 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
2043 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
2044 if (RHS == ConstantBool::True && SCI->hasOneUse())
2045 return new SetCondInst(SCI->getInverseCondition(),
2046 SCI->getOperand(0), SCI->getOperand(1));
2048 // ~(c-X) == X-c-1 == X+(-c-1)
2049 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
2050 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
2051 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
2052 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
2053 ConstantInt::get(I.getType(), 1));
2054 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
2057 // ~(~X & Y) --> (X | ~Y)
2058 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
2059 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
2060 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
2062 BinaryOperator::createNot(Op0I->getOperand(1),
2063 Op0I->getOperand(1)->getName()+".not");
2064 InsertNewInstBefore(NotY, I);
2065 return BinaryOperator::createOr(Op0NotVal, NotY);
2069 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
2070 switch (Op0I->getOpcode()) {
2071 case Instruction::Add:
2072 // ~(X-c) --> (-c-1)-X
2073 if (RHS->isAllOnesValue()) {
2074 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
2075 return BinaryOperator::createSub(
2076 ConstantExpr::getSub(NegOp0CI,
2077 ConstantInt::get(I.getType(), 1)),
2078 Op0I->getOperand(0));
2081 case Instruction::And:
2082 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
2083 if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue())
2084 return BinaryOperator::createOr(Op0, RHS);
2086 case Instruction::Or:
2087 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
2088 if (ConstantExpr::getAnd(RHS, Op0CI) == RHS)
2089 return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS));
2095 // Try to fold constant and into select arguments.
2096 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2097 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2099 if (isa<PHINode>(Op0))
2100 if (Instruction *NV = FoldOpIntoPhi(I))
2104 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
2106 return ReplaceInstUsesWith(I,
2107 ConstantIntegral::getAllOnesValue(I.getType()));
2109 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
2111 return ReplaceInstUsesWith(I,
2112 ConstantIntegral::getAllOnesValue(I.getType()));
2114 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
2115 if (Op1I->getOpcode() == Instruction::Or) {
2116 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
2117 cast<BinaryOperator>(Op1I)->swapOperands();
2119 std::swap(Op0, Op1);
2120 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
2122 std::swap(Op0, Op1);
2124 } else if (Op1I->getOpcode() == Instruction::Xor) {
2125 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
2126 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
2127 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
2128 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
2131 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
2132 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
2133 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
2134 cast<BinaryOperator>(Op0I)->swapOperands();
2135 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
2136 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
2137 Op1->getName()+".not"), I);
2138 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
2140 } else if (Op0I->getOpcode() == Instruction::Xor) {
2141 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
2142 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2143 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
2144 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2147 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
2148 Value *A, *B; ConstantInt *C1, *C2;
2149 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2150 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) &&
2151 ConstantExpr::getAnd(C1, C2)->isNullValue())
2152 return BinaryOperator::createOr(Op0, Op1);
2154 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
2155 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
2156 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2159 return Changed ? &I : 0;
2162 /// MulWithOverflow - Compute Result = In1*In2, returning true if the result
2163 /// overflowed for this type.
2164 static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2166 Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
2167 return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
2170 static bool isPositive(ConstantInt *C) {
2171 return cast<ConstantSInt>(C)->getValue() >= 0;
2174 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
2175 /// overflowed for this type.
2176 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2178 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
2180 if (In1->getType()->isUnsigned())
2181 return cast<ConstantUInt>(Result)->getValue() <
2182 cast<ConstantUInt>(In1)->getValue();
2183 if (isPositive(In1) != isPositive(In2))
2185 if (isPositive(In1))
2186 return cast<ConstantSInt>(Result)->getValue() <
2187 cast<ConstantSInt>(In1)->getValue();
2188 return cast<ConstantSInt>(Result)->getValue() >
2189 cast<ConstantSInt>(In1)->getValue();
2192 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
2193 /// code necessary to compute the offset from the base pointer (without adding
2194 /// in the base pointer). Return the result as a signed integer of intptr size.
2195 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
2196 TargetData &TD = IC.getTargetData();
2197 gep_type_iterator GTI = gep_type_begin(GEP);
2198 const Type *UIntPtrTy = TD.getIntPtrType();
2199 const Type *SIntPtrTy = UIntPtrTy->getSignedVersion();
2200 Value *Result = Constant::getNullValue(SIntPtrTy);
2202 // Build a mask for high order bits.
2203 uint64_t PtrSizeMask = ~0ULL;
2204 PtrSizeMask >>= 64-(TD.getPointerSize()*8);
2206 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
2207 Value *Op = GEP->getOperand(i);
2208 uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask;
2209 Constant *Scale = ConstantExpr::getCast(ConstantUInt::get(UIntPtrTy, Size),
2211 if (Constant *OpC = dyn_cast<Constant>(Op)) {
2212 if (!OpC->isNullValue()) {
2213 OpC = ConstantExpr::getCast(OpC, SIntPtrTy);
2214 Scale = ConstantExpr::getMul(OpC, Scale);
2215 if (Constant *RC = dyn_cast<Constant>(Result))
2216 Result = ConstantExpr::getAdd(RC, Scale);
2218 // Emit an add instruction.
2219 Result = IC.InsertNewInstBefore(
2220 BinaryOperator::createAdd(Result, Scale,
2221 GEP->getName()+".offs"), I);
2225 // Convert to correct type.
2226 Op = IC.InsertNewInstBefore(new CastInst(Op, SIntPtrTy,
2227 Op->getName()+".c"), I);
2229 // We'll let instcombine(mul) convert this to a shl if possible.
2230 Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
2231 GEP->getName()+".idx"), I);
2233 // Emit an add instruction.
2234 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
2235 GEP->getName()+".offs"), I);
2241 /// FoldGEPSetCC - Fold comparisons between a GEP instruction and something
2242 /// else. At this point we know that the GEP is on the LHS of the comparison.
2243 Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS,
2244 Instruction::BinaryOps Cond,
2246 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
2248 if (CastInst *CI = dyn_cast<CastInst>(RHS))
2249 if (isa<PointerType>(CI->getOperand(0)->getType()))
2250 RHS = CI->getOperand(0);
2252 Value *PtrBase = GEPLHS->getOperand(0);
2253 if (PtrBase == RHS) {
2254 // As an optimization, we don't actually have to compute the actual value of
2255 // OFFSET if this is a seteq or setne comparison, just return whether each
2256 // index is zero or not.
2257 if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) {
2258 Instruction *InVal = 0;
2259 gep_type_iterator GTI = gep_type_begin(GEPLHS);
2260 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
2262 if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
2263 if (isa<UndefValue>(C)) // undef index -> undef.
2264 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
2265 if (C->isNullValue())
2267 else if (TD->getTypeSize(GTI.getIndexedType()) == 0) {
2268 EmitIt = false; // This is indexing into a zero sized array?
2269 } else if (isa<ConstantInt>(C))
2270 return ReplaceInstUsesWith(I, // No comparison is needed here.
2271 ConstantBool::get(Cond == Instruction::SetNE));
2276 new SetCondInst(Cond, GEPLHS->getOperand(i),
2277 Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
2281 InVal = InsertNewInstBefore(InVal, I);
2282 InsertNewInstBefore(Comp, I);
2283 if (Cond == Instruction::SetNE) // True if any are unequal
2284 InVal = BinaryOperator::createOr(InVal, Comp);
2285 else // True if all are equal
2286 InVal = BinaryOperator::createAnd(InVal, Comp);
2294 ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0
2295 ConstantBool::get(Cond == Instruction::SetEQ));
2298 // Only lower this if the setcc is the only user of the GEP or if we expect
2299 // the result to fold to a constant!
2300 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
2301 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
2302 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
2303 return new SetCondInst(Cond, Offset,
2304 Constant::getNullValue(Offset->getType()));
2306 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
2307 // If the base pointers are different, but the indices are the same, just
2308 // compare the base pointer.
2309 if (PtrBase != GEPRHS->getOperand(0)) {
2310 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
2311 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
2312 GEPRHS->getOperand(0)->getType();
2314 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2315 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2316 IndicesTheSame = false;
2320 // If all indices are the same, just compare the base pointers.
2322 return new SetCondInst(Cond, GEPLHS->getOperand(0),
2323 GEPRHS->getOperand(0));
2325 // Otherwise, the base pointers are different and the indices are
2326 // different, bail out.
2330 // If one of the GEPs has all zero indices, recurse.
2331 bool AllZeros = true;
2332 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2333 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
2334 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
2339 return FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0),
2340 SetCondInst::getSwappedCondition(Cond), I);
2342 // If the other GEP has all zero indices, recurse.
2344 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2345 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
2346 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
2351 return FoldGEPSetCC(GEPLHS, GEPRHS->getOperand(0), Cond, I);
2353 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
2354 // If the GEPs only differ by one index, compare it.
2355 unsigned NumDifferences = 0; // Keep track of # differences.
2356 unsigned DiffOperand = 0; // The operand that differs.
2357 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2358 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2359 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
2360 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
2361 // Irreconcilable differences.
2365 if (NumDifferences++) break;
2370 if (NumDifferences == 0) // SAME GEP?
2371 return ReplaceInstUsesWith(I, // No comparison is needed here.
2372 ConstantBool::get(Cond == Instruction::SetEQ));
2373 else if (NumDifferences == 1) {
2374 Value *LHSV = GEPLHS->getOperand(DiffOperand);
2375 Value *RHSV = GEPRHS->getOperand(DiffOperand);
2377 // Convert the operands to signed values to make sure to perform a
2378 // signed comparison.
2379 const Type *NewTy = LHSV->getType()->getSignedVersion();
2380 if (LHSV->getType() != NewTy)
2381 LHSV = InsertNewInstBefore(new CastInst(LHSV, NewTy,
2382 LHSV->getName()), I);
2383 if (RHSV->getType() != NewTy)
2384 RHSV = InsertNewInstBefore(new CastInst(RHSV, NewTy,
2385 RHSV->getName()), I);
2386 return new SetCondInst(Cond, LHSV, RHSV);
2390 // Only lower this if the setcc is the only user of the GEP or if we expect
2391 // the result to fold to a constant!
2392 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
2393 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
2394 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
2395 Value *L = EmitGEPOffset(GEPLHS, I, *this);
2396 Value *R = EmitGEPOffset(GEPRHS, I, *this);
2397 return new SetCondInst(Cond, L, R);
2404 Instruction *InstCombiner::visitSetCondInst(SetCondInst &I) {
2405 bool Changed = SimplifyCommutative(I);
2406 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2407 const Type *Ty = Op0->getType();
2411 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
2413 if (isa<UndefValue>(Op1)) // X setcc undef -> undef
2414 return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
2416 // setcc <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
2417 // addresses never equal each other! We already know that Op0 != Op1.
2418 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
2419 isa<ConstantPointerNull>(Op0)) &&
2420 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
2421 isa<ConstantPointerNull>(Op1)))
2422 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
2424 // setcc's with boolean values can always be turned into bitwise operations
2425 if (Ty == Type::BoolTy) {
2426 switch (I.getOpcode()) {
2427 default: assert(0 && "Invalid setcc instruction!");
2428 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
2429 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
2430 InsertNewInstBefore(Xor, I);
2431 return BinaryOperator::createNot(Xor);
2433 case Instruction::SetNE:
2434 return BinaryOperator::createXor(Op0, Op1);
2436 case Instruction::SetGT:
2437 std::swap(Op0, Op1); // Change setgt -> setlt
2439 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
2440 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2441 InsertNewInstBefore(Not, I);
2442 return BinaryOperator::createAnd(Not, Op1);
2444 case Instruction::SetGE:
2445 std::swap(Op0, Op1); // Change setge -> setle
2447 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
2448 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2449 InsertNewInstBefore(Not, I);
2450 return BinaryOperator::createOr(Not, Op1);
2455 // See if we are doing a comparison between a constant and an instruction that
2456 // can be folded into the comparison.
2457 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2458 // Check to see if we are comparing against the minimum or maximum value...
2459 if (CI->isMinValue()) {
2460 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
2461 return ReplaceInstUsesWith(I, ConstantBool::False);
2462 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
2463 return ReplaceInstUsesWith(I, ConstantBool::True);
2464 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
2465 return BinaryOperator::createSetEQ(Op0, Op1);
2466 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
2467 return BinaryOperator::createSetNE(Op0, Op1);
2469 } else if (CI->isMaxValue()) {
2470 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
2471 return ReplaceInstUsesWith(I, ConstantBool::False);
2472 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
2473 return ReplaceInstUsesWith(I, ConstantBool::True);
2474 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
2475 return BinaryOperator::createSetEQ(Op0, Op1);
2476 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
2477 return BinaryOperator::createSetNE(Op0, Op1);
2479 // Comparing against a value really close to min or max?
2480 } else if (isMinValuePlusOne(CI)) {
2481 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
2482 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
2483 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
2484 return BinaryOperator::createSetNE(Op0, SubOne(CI));
2486 } else if (isMaxValueMinusOne(CI)) {
2487 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
2488 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
2489 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
2490 return BinaryOperator::createSetNE(Op0, AddOne(CI));
2493 // If we still have a setle or setge instruction, turn it into the
2494 // appropriate setlt or setgt instruction. Since the border cases have
2495 // already been handled above, this requires little checking.
2497 if (I.getOpcode() == Instruction::SetLE)
2498 return BinaryOperator::createSetLT(Op0, AddOne(CI));
2499 if (I.getOpcode() == Instruction::SetGE)
2500 return BinaryOperator::createSetGT(Op0, SubOne(CI));
2502 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
2503 switch (LHSI->getOpcode()) {
2504 case Instruction::And:
2505 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
2506 LHSI->getOperand(0)->hasOneUse()) {
2507 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
2508 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
2509 // happens a LOT in code produced by the C front-end, for bitfield
2511 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
2512 ConstantUInt *ShAmt;
2513 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
2514 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
2515 const Type *Ty = LHSI->getType();
2517 // We can fold this as long as we can't shift unknown bits
2518 // into the mask. This can only happen with signed shift
2519 // rights, as they sign-extend.
2521 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
2522 Shift->getType()->isUnsigned();
2524 // To test for the bad case of the signed shr, see if any
2525 // of the bits shifted in could be tested after the mask.
2526 int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue();
2527 if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
2529 Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal);
2531 ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
2532 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
2538 if (Shift->getOpcode() == Instruction::Shl)
2539 NewCst = ConstantExpr::getUShr(CI, ShAmt);
2541 NewCst = ConstantExpr::getShl(CI, ShAmt);
2543 // Check to see if we are shifting out any of the bits being
2545 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
2546 // If we shifted bits out, the fold is not going to work out.
2547 // As a special case, check to see if this means that the
2548 // result is always true or false now.
2549 if (I.getOpcode() == Instruction::SetEQ)
2550 return ReplaceInstUsesWith(I, ConstantBool::False);
2551 if (I.getOpcode() == Instruction::SetNE)
2552 return ReplaceInstUsesWith(I, ConstantBool::True);
2554 I.setOperand(1, NewCst);
2555 Constant *NewAndCST;
2556 if (Shift->getOpcode() == Instruction::Shl)
2557 NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
2559 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
2560 LHSI->setOperand(1, NewAndCST);
2561 LHSI->setOperand(0, Shift->getOperand(0));
2562 WorkList.push_back(Shift); // Shift is dead.
2563 AddUsesToWorkList(I);
2571 case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
2572 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2573 switch (I.getOpcode()) {
2575 case Instruction::SetEQ:
2576 case Instruction::SetNE: {
2577 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2579 // Check that the shift amount is in range. If not, don't perform
2580 // undefined shifts. When the shift is visited it will be
2582 if (ShAmt->getValue() >= TypeBits)
2585 // If we are comparing against bits always shifted out, the
2586 // comparison cannot succeed.
2588 ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
2589 if (Comp != CI) {// Comparing against a bit that we know is zero.
2590 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2591 Constant *Cst = ConstantBool::get(IsSetNE);
2592 return ReplaceInstUsesWith(I, Cst);
2595 if (LHSI->hasOneUse()) {
2596 // Otherwise strength reduce the shift into an and.
2597 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2598 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
2601 if (CI->getType()->isUnsigned()) {
2602 Mask = ConstantUInt::get(CI->getType(), Val);
2603 } else if (ShAmtVal != 0) {
2604 Mask = ConstantSInt::get(CI->getType(), Val);
2606 Mask = ConstantInt::getAllOnesValue(CI->getType());
2610 BinaryOperator::createAnd(LHSI->getOperand(0),
2611 Mask, LHSI->getName()+".mask");
2612 Value *And = InsertNewInstBefore(AndI, I);
2613 return new SetCondInst(I.getOpcode(), And,
2614 ConstantExpr::getUShr(CI, ShAmt));
2621 case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
2622 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2623 switch (I.getOpcode()) {
2625 case Instruction::SetEQ:
2626 case Instruction::SetNE: {
2628 // Check that the shift amount is in range. If not, don't perform
2629 // undefined shifts. When the shift is visited it will be
2631 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2632 if (ShAmt->getValue() >= TypeBits)
2635 // If we are comparing against bits always shifted out, the
2636 // comparison cannot succeed.
2638 ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
2640 if (Comp != CI) {// Comparing against a bit that we know is zero.
2641 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2642 Constant *Cst = ConstantBool::get(IsSetNE);
2643 return ReplaceInstUsesWith(I, Cst);
2646 if (LHSI->hasOneUse() || CI->isNullValue()) {
2647 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2649 // Otherwise strength reduce the shift into an and.
2650 uint64_t Val = ~0ULL; // All ones.
2651 Val <<= ShAmtVal; // Shift over to the right spot.
2654 if (CI->getType()->isUnsigned()) {
2655 Val &= ~0ULL >> (64-TypeBits);
2656 Mask = ConstantUInt::get(CI->getType(), Val);
2658 Mask = ConstantSInt::get(CI->getType(), Val);
2662 BinaryOperator::createAnd(LHSI->getOperand(0),
2663 Mask, LHSI->getName()+".mask");
2664 Value *And = InsertNewInstBefore(AndI, I);
2665 return new SetCondInst(I.getOpcode(), And,
2666 ConstantExpr::getShl(CI, ShAmt));
2674 case Instruction::Div:
2675 // Fold: (div X, C1) op C2 -> range check
2676 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
2677 // Fold this div into the comparison, producing a range check.
2678 // Determine, based on the divide type, what the range is being
2679 // checked. If there is an overflow on the low or high side, remember
2680 // it, otherwise compute the range [low, hi) bounding the new value.
2681 bool LoOverflow = false, HiOverflow = 0;
2682 ConstantInt *LoBound = 0, *HiBound = 0;
2685 bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
2687 Instruction::BinaryOps Opcode = I.getOpcode();
2689 if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
2690 } else if (LHSI->getType()->isUnsigned()) { // udiv
2692 LoOverflow = ProdOV;
2693 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
2694 } else if (isPositive(DivRHS)) { // Divisor is > 0.
2695 if (CI->isNullValue()) { // (X / pos) op 0
2697 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
2699 } else if (isPositive(CI)) { // (X / pos) op pos
2701 LoOverflow = ProdOV;
2702 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
2703 } else { // (X / pos) op neg
2704 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
2705 LoOverflow = AddWithOverflow(LoBound, Prod,
2706 cast<ConstantInt>(DivRHSH));
2708 HiOverflow = ProdOV;
2710 } else { // Divisor is < 0.
2711 if (CI->isNullValue()) { // (X / neg) op 0
2712 LoBound = AddOne(DivRHS);
2713 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
2714 if (HiBound == DivRHS)
2715 LoBound = 0; // - INTMIN = INTMIN
2716 } else if (isPositive(CI)) { // (X / neg) op pos
2717 HiOverflow = LoOverflow = ProdOV;
2719 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
2720 HiBound = AddOne(Prod);
2721 } else { // (X / neg) op neg
2723 LoOverflow = HiOverflow = ProdOV;
2724 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
2727 // Dividing by a negate swaps the condition.
2728 Opcode = SetCondInst::getSwappedCondition(Opcode);
2732 Value *X = LHSI->getOperand(0);
2734 default: assert(0 && "Unhandled setcc opcode!");
2735 case Instruction::SetEQ:
2736 if (LoOverflow && HiOverflow)
2737 return ReplaceInstUsesWith(I, ConstantBool::False);
2738 else if (HiOverflow)
2739 return new SetCondInst(Instruction::SetGE, X, LoBound);
2740 else if (LoOverflow)
2741 return new SetCondInst(Instruction::SetLT, X, HiBound);
2743 return InsertRangeTest(X, LoBound, HiBound, true, I);
2744 case Instruction::SetNE:
2745 if (LoOverflow && HiOverflow)
2746 return ReplaceInstUsesWith(I, ConstantBool::True);
2747 else if (HiOverflow)
2748 return new SetCondInst(Instruction::SetLT, X, LoBound);
2749 else if (LoOverflow)
2750 return new SetCondInst(Instruction::SetGE, X, HiBound);
2752 return InsertRangeTest(X, LoBound, HiBound, false, I);
2753 case Instruction::SetLT:
2755 return ReplaceInstUsesWith(I, ConstantBool::False);
2756 return new SetCondInst(Instruction::SetLT, X, LoBound);
2757 case Instruction::SetGT:
2759 return ReplaceInstUsesWith(I, ConstantBool::False);
2760 return new SetCondInst(Instruction::SetGE, X, HiBound);
2767 // Simplify seteq and setne instructions...
2768 if (I.getOpcode() == Instruction::SetEQ ||
2769 I.getOpcode() == Instruction::SetNE) {
2770 bool isSetNE = I.getOpcode() == Instruction::SetNE;
2772 // If the first operand is (and|or|xor) with a constant, and the second
2773 // operand is a constant, simplify a bit.
2774 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
2775 switch (BO->getOpcode()) {
2776 case Instruction::Rem:
2777 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
2778 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
2780 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1)
2782 Log2(cast<ConstantSInt>(BO->getOperand(1))->getValue())) {
2783 const Type *UTy = BO->getType()->getUnsignedVersion();
2784 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
2786 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
2787 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
2788 RHSCst, BO->getName()), I);
2789 return BinaryOperator::create(I.getOpcode(), NewRem,
2790 Constant::getNullValue(UTy));
2794 case Instruction::Add:
2795 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
2796 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2797 if (BO->hasOneUse())
2798 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
2799 ConstantExpr::getSub(CI, BOp1C));
2800 } else if (CI->isNullValue()) {
2801 // Replace ((add A, B) != 0) with (A != -B) if A or B is
2802 // efficiently invertible, or if the add has just this one use.
2803 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
2805 if (Value *NegVal = dyn_castNegVal(BOp1))
2806 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
2807 else if (Value *NegVal = dyn_castNegVal(BOp0))
2808 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
2809 else if (BO->hasOneUse()) {
2810 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
2812 InsertNewInstBefore(Neg, I);
2813 return new SetCondInst(I.getOpcode(), BOp0, Neg);
2817 case Instruction::Xor:
2818 // For the xor case, we can xor two constants together, eliminating
2819 // the explicit xor.
2820 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
2821 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
2822 ConstantExpr::getXor(CI, BOC));
2825 case Instruction::Sub:
2826 // Replace (([sub|xor] A, B) != 0) with (A != B)
2827 if (CI->isNullValue())
2828 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
2832 case Instruction::Or:
2833 // If bits are being or'd in that are not present in the constant we
2834 // are comparing against, then the comparison could never succeed!
2835 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
2836 Constant *NotCI = ConstantExpr::getNot(CI);
2837 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
2838 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
2842 case Instruction::And:
2843 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2844 // If bits are being compared against that are and'd out, then the
2845 // comparison can never succeed!
2846 if (!ConstantExpr::getAnd(CI,
2847 ConstantExpr::getNot(BOC))->isNullValue())
2848 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
2850 // If we have ((X & C) == C), turn it into ((X & C) != 0).
2851 if (CI == BOC && isOneBitSet(CI))
2852 return new SetCondInst(isSetNE ? Instruction::SetEQ :
2853 Instruction::SetNE, Op0,
2854 Constant::getNullValue(CI->getType()));
2856 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
2857 // to be a signed value as appropriate.
2858 if (isSignBit(BOC)) {
2859 Value *X = BO->getOperand(0);
2860 // If 'X' is not signed, insert a cast now...
2861 if (!BOC->getType()->isSigned()) {
2862 const Type *DestTy = BOC->getType()->getSignedVersion();
2863 X = InsertCastBefore(X, DestTy, I);
2865 return new SetCondInst(isSetNE ? Instruction::SetLT :
2866 Instruction::SetGE, X,
2867 Constant::getNullValue(X->getType()));
2870 // ((X & ~7) == 0) --> X < 8
2871 if (CI->isNullValue() && isHighOnes(BOC)) {
2872 Value *X = BO->getOperand(0);
2873 Constant *NegX = ConstantExpr::getNeg(BOC);
2875 // If 'X' is signed, insert a cast now.
2876 if (NegX->getType()->isSigned()) {
2877 const Type *DestTy = NegX->getType()->getUnsignedVersion();
2878 X = InsertCastBefore(X, DestTy, I);
2879 NegX = ConstantExpr::getCast(NegX, DestTy);
2882 return new SetCondInst(isSetNE ? Instruction::SetGE :
2883 Instruction::SetLT, X, NegX);
2890 } else { // Not a SetEQ/SetNE
2891 // If the LHS is a cast from an integral value of the same size,
2892 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
2893 Value *CastOp = Cast->getOperand(0);
2894 const Type *SrcTy = CastOp->getType();
2895 unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits();
2896 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
2897 SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
2898 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
2899 "Source and destination signednesses should differ!");
2900 if (Cast->getType()->isSigned()) {
2901 // If this is a signed comparison, check for comparisons in the
2902 // vicinity of zero.
2903 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
2905 return BinaryOperator::createSetGT(CastOp,
2906 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize-1))-1));
2907 else if (I.getOpcode() == Instruction::SetGT &&
2908 cast<ConstantSInt>(CI)->getValue() == -1)
2909 // X > -1 => x < 128
2910 return BinaryOperator::createSetLT(CastOp,
2911 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize-1)));
2913 ConstantUInt *CUI = cast<ConstantUInt>(CI);
2914 if (I.getOpcode() == Instruction::SetLT &&
2915 CUI->getValue() == 1ULL << (SrcTySize-1))
2916 // X < 128 => X > -1
2917 return BinaryOperator::createSetGT(CastOp,
2918 ConstantSInt::get(SrcTy, -1));
2919 else if (I.getOpcode() == Instruction::SetGT &&
2920 CUI->getValue() == (1ULL << (SrcTySize-1))-1)
2922 return BinaryOperator::createSetLT(CastOp,
2923 Constant::getNullValue(SrcTy));
2930 // Handle setcc with constant RHS's that can be integer, FP or pointer.
2931 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
2932 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
2933 switch (LHSI->getOpcode()) {
2934 case Instruction::GetElementPtr:
2935 if (RHSC->isNullValue()) {
2936 // Transform setcc GEP P, int 0, int 0, int 0, null -> setcc P, null
2937 bool isAllZeros = true;
2938 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
2939 if (!isa<Constant>(LHSI->getOperand(i)) ||
2940 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
2945 return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),
2946 Constant::getNullValue(LHSI->getOperand(0)->getType()));
2950 case Instruction::PHI:
2951 if (Instruction *NV = FoldOpIntoPhi(I))
2954 case Instruction::Select:
2955 // If either operand of the select is a constant, we can fold the
2956 // comparison into the select arms, which will cause one to be
2957 // constant folded and the select turned into a bitwise or.
2958 Value *Op1 = 0, *Op2 = 0;
2959 if (LHSI->hasOneUse()) {
2960 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
2961 // Fold the known value into the constant operand.
2962 Op1 = ConstantExpr::get(I.getOpcode(), C, RHSC);
2963 // Insert a new SetCC of the other select operand.
2964 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
2965 LHSI->getOperand(2), RHSC,
2967 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
2968 // Fold the known value into the constant operand.
2969 Op2 = ConstantExpr::get(I.getOpcode(), C, RHSC);
2970 // Insert a new SetCC of the other select operand.
2971 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
2972 LHSI->getOperand(1), RHSC,
2978 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
2983 // If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now.
2984 if (User *GEP = dyn_castGetElementPtr(Op0))
2985 if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I))
2987 if (User *GEP = dyn_castGetElementPtr(Op1))
2988 if (Instruction *NI = FoldGEPSetCC(GEP, Op0,
2989 SetCondInst::getSwappedCondition(I.getOpcode()), I))
2992 // Test to see if the operands of the setcc are casted versions of other
2993 // values. If the cast can be stripped off both arguments, we do so now.
2994 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
2995 Value *CastOp0 = CI->getOperand(0);
2996 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
2997 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
2998 (I.getOpcode() == Instruction::SetEQ ||
2999 I.getOpcode() == Instruction::SetNE)) {
3000 // We keep moving the cast from the left operand over to the right
3001 // operand, where it can often be eliminated completely.
3004 // If operand #1 is a cast instruction, see if we can eliminate it as
3006 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
3007 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
3009 Op1 = CI2->getOperand(0);
3011 // If Op1 is a constant, we can fold the cast into the constant.
3012 if (Op1->getType() != Op0->getType())
3013 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
3014 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
3016 // Otherwise, cast the RHS right before the setcc
3017 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
3018 InsertNewInstBefore(cast<Instruction>(Op1), I);
3020 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
3023 // Handle the special case of: setcc (cast bool to X), <cst>
3024 // This comes up when you have code like
3027 // For generality, we handle any zero-extension of any operand comparison
3028 // with a constant or another cast from the same type.
3029 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
3030 if (Instruction *R = visitSetCondInstWithCastAndCast(I))
3033 return Changed ? &I : 0;
3036 // visitSetCondInstWithCastAndCast - Handle setcond (cast x to y), (cast/cst).
3037 // We only handle extending casts so far.
3039 Instruction *InstCombiner::visitSetCondInstWithCastAndCast(SetCondInst &SCI) {
3040 Value *LHSCIOp = cast<CastInst>(SCI.getOperand(0))->getOperand(0);
3041 const Type *SrcTy = LHSCIOp->getType();
3042 const Type *DestTy = SCI.getOperand(0)->getType();
3045 if (!DestTy->isIntegral() || !SrcTy->isIntegral())
3048 unsigned SrcBits = SrcTy->getPrimitiveSizeInBits();
3049 unsigned DestBits = DestTy->getPrimitiveSizeInBits();
3050 if (SrcBits >= DestBits) return 0; // Only handle extending cast.
3052 // Is this a sign or zero extension?
3053 bool isSignSrc = SrcTy->isSigned();
3054 bool isSignDest = DestTy->isSigned();
3056 if (CastInst *CI = dyn_cast<CastInst>(SCI.getOperand(1))) {
3057 // Not an extension from the same type?
3058 RHSCIOp = CI->getOperand(0);
3059 if (RHSCIOp->getType() != LHSCIOp->getType()) return 0;
3060 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(SCI.getOperand(1))) {
3061 // Compute the constant that would happen if we truncated to SrcTy then
3062 // reextended to DestTy.
3063 Constant *Res = ConstantExpr::getCast(CI, SrcTy);
3065 if (ConstantExpr::getCast(Res, DestTy) == CI) {
3068 // If the value cannot be represented in the shorter type, we cannot emit
3069 // a simple comparison.
3070 if (SCI.getOpcode() == Instruction::SetEQ)
3071 return ReplaceInstUsesWith(SCI, ConstantBool::False);
3072 if (SCI.getOpcode() == Instruction::SetNE)
3073 return ReplaceInstUsesWith(SCI, ConstantBool::True);
3075 // Evaluate the comparison for LT.
3077 if (DestTy->isSigned()) {
3078 // We're performing a signed comparison.
3080 // Signed extend and signed comparison.
3081 if (cast<ConstantSInt>(CI)->getValue() < 0) // X < (small) --> false
3082 Result = ConstantBool::False;
3084 Result = ConstantBool::True; // X < (large) --> true
3086 // Unsigned extend and signed comparison.
3087 if (cast<ConstantSInt>(CI)->getValue() < 0)
3088 Result = ConstantBool::False;
3090 Result = ConstantBool::True;
3093 // We're performing an unsigned comparison.
3095 // Unsigned extend & compare -> always true.
3096 Result = ConstantBool::True;
3098 // We're performing an unsigned comp with a sign extended value.
3099 // This is true if the input is >= 0. [aka >s -1]
3100 Constant *NegOne = ConstantIntegral::getAllOnesValue(SrcTy);
3101 Result = InsertNewInstBefore(BinaryOperator::createSetGT(LHSCIOp,
3102 NegOne, SCI.getName()), SCI);
3106 // Finally, return the value computed.
3107 if (SCI.getOpcode() == Instruction::SetLT) {
3108 return ReplaceInstUsesWith(SCI, Result);
3110 assert(SCI.getOpcode()==Instruction::SetGT &&"SetCC should be folded!");
3111 if (Constant *CI = dyn_cast<Constant>(Result))
3112 return ReplaceInstUsesWith(SCI, ConstantExpr::getNot(CI));
3114 return BinaryOperator::createNot(Result);
3121 // Okay, just insert a compare of the reduced operands now!
3122 return BinaryOperator::create(SCI.getOpcode(), LHSCIOp, RHSCIOp);
3125 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
3126 assert(I.getOperand(1)->getType() == Type::UByteTy);
3127 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3128 bool isLeftShift = I.getOpcode() == Instruction::Shl;
3130 // shl X, 0 == X and shr X, 0 == X
3131 // shl 0, X == 0 and shr 0, X == 0
3132 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
3133 Op0 == Constant::getNullValue(Op0->getType()))
3134 return ReplaceInstUsesWith(I, Op0);
3136 if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
3137 if (!isLeftShift && I.getType()->isSigned())
3138 return ReplaceInstUsesWith(I, Op0);
3139 else // undef << X -> 0 AND undef >>u X -> 0
3140 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3142 if (isa<UndefValue>(Op1)) {
3143 if (isLeftShift || I.getType()->isUnsigned())// X << undef, X >>u undef -> 0
3144 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3146 return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X
3149 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
3151 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
3152 if (CSI->isAllOnesValue())
3153 return ReplaceInstUsesWith(I, CSI);
3155 // Try to fold constant and into select arguments.
3156 if (isa<Constant>(Op0))
3157 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
3158 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3161 // See if we can turn a signed shr into an unsigned shr.
3162 if (!isLeftShift && I.getType()->isSigned()) {
3163 if (MaskedValueIsZero(Op0, ConstantInt::getMinValue(I.getType()))) {
3164 Value *V = InsertCastBefore(Op0, I.getType()->getUnsignedVersion(), I);
3165 V = InsertNewInstBefore(new ShiftInst(Instruction::Shr, V, Op1,
3167 return new CastInst(V, I.getType());
3171 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
3172 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
3173 // of a signed value.
3175 unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits();
3176 if (CUI->getValue() >= TypeBits) {
3177 if (!Op0->getType()->isSigned() || isLeftShift)
3178 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
3180 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
3185 // ((X*C1) << C2) == (X * (C1 << C2))
3186 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
3187 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
3188 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
3189 return BinaryOperator::createMul(BO->getOperand(0),
3190 ConstantExpr::getShl(BOOp, CUI));
3192 // Try to fold constant and into select arguments.
3193 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3194 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3196 if (isa<PHINode>(Op0))
3197 if (Instruction *NV = FoldOpIntoPhi(I))
3200 if (Op0->hasOneUse()) {
3201 // If this is a SHL of a sign-extending cast, see if we can turn the input
3202 // into a zero extending cast (a simple strength reduction).
3203 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3204 const Type *SrcTy = CI->getOperand(0)->getType();
3205 if (isLeftShift && SrcTy->isInteger() && SrcTy->isSigned() &&
3206 SrcTy->getPrimitiveSizeInBits() <
3207 CI->getType()->getPrimitiveSizeInBits()) {
3208 // We can change it to a zero extension if we are shifting out all of
3209 // the sign extended bits. To check this, form a mask of all of the
3210 // sign extend bits, then shift them left and see if we have anything
3212 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); // 1111
3213 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); // 00001111
3214 Mask = ConstantExpr::getNot(Mask); // 1's in the sign bits: 11110000
3215 if (ConstantExpr::getShl(Mask, CUI)->isNullValue()) {
3216 // If the shift is nuking all of the sign bits, change this to a
3217 // zero extension cast. To do this, cast the cast input to
3218 // unsigned, then to the requested size.
3219 Value *CastOp = CI->getOperand(0);
3221 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
3222 CI->getName()+".uns");
3223 NC = InsertNewInstBefore(NC, I);
3224 // Finally, insert a replacement for CI.
3225 NC = new CastInst(NC, CI->getType(), CI->getName());
3227 NC = InsertNewInstBefore(NC, I);
3228 WorkList.push_back(CI); // Delete CI later.
3229 I.setOperand(0, NC);
3230 return &I; // The SHL operand was modified.
3235 // If the operand is an bitwise operator with a constant RHS, and the
3236 // shift is the only use, we can pull it out of the shift.
3237 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0))
3238 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
3239 bool isValid = true; // Valid only for And, Or, Xor
3240 bool highBitSet = false; // Transform if high bit of constant set?
3242 switch (Op0BO->getOpcode()) {
3243 default: isValid = false; break; // Do not perform transform!
3244 case Instruction::Add:
3245 isValid = isLeftShift;
3247 case Instruction::Or:
3248 case Instruction::Xor:
3251 case Instruction::And:
3256 // If this is a signed shift right, and the high bit is modified
3257 // by the logical operation, do not perform the transformation.
3258 // The highBitSet boolean indicates the value of the high bit of
3259 // the constant which would cause it to be modified for this
3262 if (isValid && !isLeftShift && !I.getType()->isUnsigned()) {
3263 uint64_t Val = Op0C->getRawValue();
3264 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
3268 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI);
3270 Instruction *NewShift =
3271 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI,
3274 InsertNewInstBefore(NewShift, I);
3276 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
3282 // If this is a shift of a shift, see if we can fold the two together...
3283 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
3284 if (ConstantUInt *ShiftAmt1C =
3285 dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) {
3286 unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getValue();
3287 unsigned ShiftAmt2 = (unsigned)CUI->getValue();
3289 // Check for (A << c1) << c2 and (A >> c1) >> c2
3290 if (I.getOpcode() == Op0SI->getOpcode()) {
3291 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
3292 if (Op0->getType()->getPrimitiveSizeInBits() < Amt)
3293 Amt = Op0->getType()->getPrimitiveSizeInBits();
3294 return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
3295 ConstantUInt::get(Type::UByteTy, Amt));
3298 // Check for (A << c1) >> c2 or visaversa. If we are dealing with
3299 // signed types, we can only support the (A >> c1) << c2 configuration,
3300 // because it can not turn an arbitrary bit of A into a sign bit.
3301 if (I.getType()->isUnsigned() || isLeftShift) {
3302 // Calculate bitmask for what gets shifted off the edge...
3303 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
3305 C = ConstantExpr::getShl(C, ShiftAmt1C);
3307 C = ConstantExpr::getShr(C, ShiftAmt1C);
3310 BinaryOperator::createAnd(Op0SI->getOperand(0), C,
3311 Op0SI->getOperand(0)->getName()+".mask");
3312 InsertNewInstBefore(Mask, I);
3314 // Figure out what flavor of shift we should use...
3315 if (ShiftAmt1 == ShiftAmt2)
3316 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
3317 else if (ShiftAmt1 < ShiftAmt2) {
3318 return new ShiftInst(I.getOpcode(), Mask,
3319 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
3321 return new ShiftInst(Op0SI->getOpcode(), Mask,
3322 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
3338 /// getCastType - In the future, we will split the cast instruction into these
3339 /// various types. Until then, we have to do the analysis here.
3340 static CastType getCastType(const Type *Src, const Type *Dest) {
3341 assert(Src->isIntegral() && Dest->isIntegral() &&
3342 "Only works on integral types!");
3343 unsigned SrcSize = Src->getPrimitiveSizeInBits();
3344 unsigned DestSize = Dest->getPrimitiveSizeInBits();
3346 if (SrcSize == DestSize) return Noop;
3347 if (SrcSize > DestSize) return Truncate;
3348 if (Src->isSigned()) return Signext;
3353 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
3356 static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
3357 const Type *DstTy, TargetData *TD) {
3359 // It is legal to eliminate the instruction if casting A->B->A if the sizes
3360 // are identical and the bits don't get reinterpreted (for example
3361 // int->float->int would not be allowed).
3362 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
3365 // If we are casting between pointer and integer types, treat pointers as
3366 // integers of the appropriate size for the code below.
3367 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
3368 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
3369 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
3371 // Allow free casting and conversion of sizes as long as the sign doesn't
3373 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
3374 CastType FirstCast = getCastType(SrcTy, MidTy);
3375 CastType SecondCast = getCastType(MidTy, DstTy);
3377 // Capture the effect of these two casts. If the result is a legal cast,
3378 // the CastType is stored here, otherwise a special code is used.
3379 static const unsigned CastResult[] = {
3380 // First cast is noop
3382 // First cast is a truncate
3383 1, 1, 4, 4, // trunc->extend is not safe to eliminate
3384 // First cast is a sign ext
3385 2, 5, 2, 4, // signext->zeroext never ok
3386 // First cast is a zero ext
3390 unsigned Result = CastResult[FirstCast*4+SecondCast];
3392 default: assert(0 && "Illegal table value!");
3397 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
3398 // truncates, we could eliminate more casts.
3399 return (unsigned)getCastType(SrcTy, DstTy) == Result;
3401 return false; // Not possible to eliminate this here.
3403 // Sign or zero extend followed by truncate is always ok if the result
3404 // is a truncate or noop.
3405 CastType ResultCast = getCastType(SrcTy, DstTy);
3406 if (ResultCast == Noop || ResultCast == Truncate)
3408 // Otherwise we are still growing the value, we are only safe if the
3409 // result will match the sign/zeroextendness of the result.
3410 return ResultCast == FirstCast;
3416 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
3417 if (V->getType() == Ty || isa<Constant>(V)) return false;
3418 if (const CastInst *CI = dyn_cast<CastInst>(V))
3419 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
3425 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
3426 /// InsertBefore instruction. This is specialized a bit to avoid inserting
3427 /// casts that are known to not do anything...
3429 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
3430 Instruction *InsertBefore) {
3431 if (V->getType() == DestTy) return V;
3432 if (Constant *C = dyn_cast<Constant>(V))
3433 return ConstantExpr::getCast(C, DestTy);
3435 CastInst *CI = new CastInst(V, DestTy, V->getName());
3436 InsertNewInstBefore(CI, *InsertBefore);
3440 // CastInst simplification
3442 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
3443 Value *Src = CI.getOperand(0);
3445 // If the user is casting a value to the same type, eliminate this cast
3447 if (CI.getType() == Src->getType())
3448 return ReplaceInstUsesWith(CI, Src);
3450 if (isa<UndefValue>(Src)) // cast undef -> undef
3451 return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
3453 // If casting the result of another cast instruction, try to eliminate this
3456 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
3457 Value *A = CSrc->getOperand(0);
3458 if (isEliminableCastOfCast(A->getType(), CSrc->getType(),
3459 CI.getType(), TD)) {
3460 // This instruction now refers directly to the cast's src operand. This
3461 // has a good chance of making CSrc dead.
3462 CI.setOperand(0, CSrc->getOperand(0));
3466 // If this is an A->B->A cast, and we are dealing with integral types, try
3467 // to convert this into a logical 'and' instruction.
3469 if (A->getType()->isInteger() &&
3470 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
3471 CSrc->getType()->isUnsigned() && // B->A cast must zero extend
3472 CSrc->getType()->getPrimitiveSizeInBits() <
3473 CI.getType()->getPrimitiveSizeInBits()&&
3474 A->getType()->getPrimitiveSizeInBits() ==
3475 CI.getType()->getPrimitiveSizeInBits()) {
3476 assert(CSrc->getType() != Type::ULongTy &&
3477 "Cannot have type bigger than ulong!");
3478 uint64_t AndValue = ~0ULL>>(64-CSrc->getType()->getPrimitiveSizeInBits());
3479 Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(),
3481 AndOp = ConstantExpr::getCast(AndOp, A->getType());
3482 Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
3483 if (And->getType() != CI.getType()) {
3484 And->setName(CSrc->getName()+".mask");
3485 InsertNewInstBefore(And, CI);
3486 And = new CastInst(And, CI.getType());
3492 // If this is a cast to bool, turn it into the appropriate setne instruction.
3493 if (CI.getType() == Type::BoolTy)
3494 return BinaryOperator::createSetNE(CI.getOperand(0),
3495 Constant::getNullValue(CI.getOperand(0)->getType()));
3497 // If casting the result of a getelementptr instruction with no offset, turn
3498 // this into a cast of the original pointer!
3500 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
3501 bool AllZeroOperands = true;
3502 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
3503 if (!isa<Constant>(GEP->getOperand(i)) ||
3504 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
3505 AllZeroOperands = false;
3508 if (AllZeroOperands) {
3509 CI.setOperand(0, GEP->getOperand(0));
3514 // If we are casting a malloc or alloca to a pointer to a type of the same
3515 // size, rewrite the allocation instruction to allocate the "right" type.
3517 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
3518 if (AI->hasOneUse() && !AI->isArrayAllocation())
3519 if (const PointerType *PTy = dyn_cast<PointerType>(CI.getType())) {
3520 // Get the type really allocated and the type casted to...
3521 const Type *AllocElTy = AI->getAllocatedType();
3522 const Type *CastElTy = PTy->getElementType();
3523 if (AllocElTy->isSized() && CastElTy->isSized()) {
3524 uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
3525 uint64_t CastElTySize = TD->getTypeSize(CastElTy);
3527 // If the allocation is for an even multiple of the cast type size
3528 if (CastElTySize && (AllocElTySize % CastElTySize == 0)) {
3529 Value *Amt = ConstantUInt::get(Type::UIntTy,
3530 AllocElTySize/CastElTySize);
3531 std::string Name = AI->getName(); AI->setName("");
3532 AllocationInst *New;
3533 if (isa<MallocInst>(AI))
3534 New = new MallocInst(CastElTy, Amt, Name);
3536 New = new AllocaInst(CastElTy, Amt, Name);
3537 InsertNewInstBefore(New, *AI);
3538 return ReplaceInstUsesWith(CI, New);
3543 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
3544 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
3546 if (isa<PHINode>(Src))
3547 if (Instruction *NV = FoldOpIntoPhi(CI))
3550 // If the source value is an instruction with only this use, we can attempt to
3551 // propagate the cast into the instruction. Also, only handle integral types
3553 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
3554 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
3555 CI.getType()->isInteger()) { // Don't mess with casts to bool here
3556 const Type *DestTy = CI.getType();
3557 unsigned SrcBitSize = Src->getType()->getPrimitiveSizeInBits();
3558 unsigned DestBitSize = DestTy->getPrimitiveSizeInBits();
3560 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
3561 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
3563 switch (SrcI->getOpcode()) {
3564 case Instruction::Add:
3565 case Instruction::Mul:
3566 case Instruction::And:
3567 case Instruction::Or:
3568 case Instruction::Xor:
3569 // If we are discarding information, or just changing the sign, rewrite.
3570 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
3571 // Don't insert two casts if they cannot be eliminated. We allow two
3572 // casts to be inserted if the sizes are the same. This could only be
3573 // converting signedness, which is a noop.
3574 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
3575 !ValueRequiresCast(Op0, DestTy, TD)) {
3576 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
3577 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
3578 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
3579 ->getOpcode(), Op0c, Op1c);
3583 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
3584 if (SrcBitSize == 1 && SrcI->getOpcode() == Instruction::Xor &&
3585 Op1 == ConstantBool::True &&
3586 (!Op0->hasOneUse() || !isa<SetCondInst>(Op0))) {
3587 Value *New = InsertOperandCastBefore(Op0, DestTy, &CI);
3588 return BinaryOperator::createXor(New,
3589 ConstantInt::get(CI.getType(), 1));
3592 case Instruction::Shl:
3593 // Allow changing the sign of the source operand. Do not allow changing
3594 // the size of the shift, UNLESS the shift amount is a constant. We
3595 // mush not change variable sized shifts to a smaller size, because it
3596 // is undefined to shift more bits out than exist in the value.
3597 if (DestBitSize == SrcBitSize ||
3598 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
3599 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
3600 return new ShiftInst(Instruction::Shl, Op0c, Op1);
3603 case Instruction::Shr:
3604 // If this is a signed shr, and if all bits shifted in are about to be
3605 // truncated off, turn it into an unsigned shr to allow greater
3607 if (DestBitSize < SrcBitSize && Src->getType()->isSigned() &&
3608 isa<ConstantInt>(Op1)) {
3609 unsigned ShiftAmt = cast<ConstantUInt>(Op1)->getValue();
3610 if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
3611 // Convert to unsigned.
3612 Value *N1 = InsertOperandCastBefore(Op0,
3613 Op0->getType()->getUnsignedVersion(), &CI);
3614 // Insert the new shift, which is now unsigned.
3615 N1 = InsertNewInstBefore(new ShiftInst(Instruction::Shr, N1,
3616 Op1, Src->getName()), CI);
3617 return new CastInst(N1, CI.getType());
3622 case Instruction::SetNE:
3623 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
3624 if (Op1C->getRawValue() == 0) {
3625 // If the input only has the low bit set, simplify directly.
3627 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
3628 // cast (X != 0) to int --> X if X&~1 == 0
3629 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
3630 if (CI.getType() == Op0->getType())
3631 return ReplaceInstUsesWith(CI, Op0);
3633 return new CastInst(Op0, CI.getType());
3636 // If the input is an and with a single bit, shift then simplify.
3637 ConstantInt *AndRHS;
3638 if (match(Op0, m_And(m_Value(), m_ConstantInt(AndRHS))))
3639 if (AndRHS->getRawValue() &&
3640 (AndRHS->getRawValue() & (AndRHS->getRawValue()-1)) == 0) {
3641 unsigned ShiftAmt = Log2(AndRHS->getRawValue());
3642 // Perform an unsigned shr by shiftamt. Convert input to
3643 // unsigned if it is signed.
3645 if (In->getType()->isSigned())
3646 In = InsertNewInstBefore(new CastInst(In,
3647 In->getType()->getUnsignedVersion(), In->getName()),CI);
3648 // Insert the shift to put the result in the low bit.
3649 In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In,
3650 ConstantInt::get(Type::UByteTy, ShiftAmt),
3651 In->getName()+".lobit"), CI);
3652 if (CI.getType() == In->getType())
3653 return ReplaceInstUsesWith(CI, In);
3655 return new CastInst(In, CI.getType());
3660 case Instruction::SetEQ:
3661 // We if we are just checking for a seteq of a single bit and casting it
3662 // to an integer. If so, shift the bit to the appropriate place then
3663 // cast to integer to avoid the comparison.
3664 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
3665 // Is Op1C a power of two or zero?
3666 if ((Op1C->getRawValue() & Op1C->getRawValue()-1) == 0) {
3667 // cast (X == 1) to int -> X iff X has only the low bit set.
3668 if (Op1C->getRawValue() == 1) {
3670 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
3671 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
3672 if (CI.getType() == Op0->getType())
3673 return ReplaceInstUsesWith(CI, Op0);
3675 return new CastInst(Op0, CI.getType());
3686 /// GetSelectFoldableOperands - We want to turn code that looks like this:
3688 /// %D = select %cond, %C, %A
3690 /// %C = select %cond, %B, 0
3693 /// Assuming that the specified instruction is an operand to the select, return
3694 /// a bitmask indicating which operands of this instruction are foldable if they
3695 /// equal the other incoming value of the select.
3697 static unsigned GetSelectFoldableOperands(Instruction *I) {
3698 switch (I->getOpcode()) {
3699 case Instruction::Add:
3700 case Instruction::Mul:
3701 case Instruction::And:
3702 case Instruction::Or:
3703 case Instruction::Xor:
3704 return 3; // Can fold through either operand.
3705 case Instruction::Sub: // Can only fold on the amount subtracted.
3706 case Instruction::Shl: // Can only fold on the shift amount.
3707 case Instruction::Shr:
3710 return 0; // Cannot fold
3714 /// GetSelectFoldableConstant - For the same transformation as the previous
3715 /// function, return the identity constant that goes into the select.
3716 static Constant *GetSelectFoldableConstant(Instruction *I) {
3717 switch (I->getOpcode()) {
3718 default: assert(0 && "This cannot happen!"); abort();
3719 case Instruction::Add:
3720 case Instruction::Sub:
3721 case Instruction::Or:
3722 case Instruction::Xor:
3723 return Constant::getNullValue(I->getType());
3724 case Instruction::Shl:
3725 case Instruction::Shr:
3726 return Constant::getNullValue(Type::UByteTy);
3727 case Instruction::And:
3728 return ConstantInt::getAllOnesValue(I->getType());
3729 case Instruction::Mul:
3730 return ConstantInt::get(I->getType(), 1);
3734 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
3735 /// have the same opcode and only one use each. Try to simplify this.
3736 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
3738 if (TI->getNumOperands() == 1) {
3739 // If this is a non-volatile load or a cast from the same type,
3741 if (TI->getOpcode() == Instruction::Cast) {
3742 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
3745 return 0; // unknown unary op.
3748 // Fold this by inserting a select from the input values.
3749 SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
3750 FI->getOperand(0), SI.getName()+".v");
3751 InsertNewInstBefore(NewSI, SI);
3752 return new CastInst(NewSI, TI->getType());
3755 // Only handle binary operators here.
3756 if (!isa<ShiftInst>(TI) && !isa<BinaryOperator>(TI))
3759 // Figure out if the operations have any operands in common.
3760 Value *MatchOp, *OtherOpT, *OtherOpF;
3762 if (TI->getOperand(0) == FI->getOperand(0)) {
3763 MatchOp = TI->getOperand(0);
3764 OtherOpT = TI->getOperand(1);
3765 OtherOpF = FI->getOperand(1);
3766 MatchIsOpZero = true;
3767 } else if (TI->getOperand(1) == FI->getOperand(1)) {
3768 MatchOp = TI->getOperand(1);
3769 OtherOpT = TI->getOperand(0);
3770 OtherOpF = FI->getOperand(0);
3771 MatchIsOpZero = false;
3772 } else if (!TI->isCommutative()) {
3774 } else if (TI->getOperand(0) == FI->getOperand(1)) {
3775 MatchOp = TI->getOperand(0);
3776 OtherOpT = TI->getOperand(1);
3777 OtherOpF = FI->getOperand(0);
3778 MatchIsOpZero = true;
3779 } else if (TI->getOperand(1) == FI->getOperand(0)) {
3780 MatchOp = TI->getOperand(1);
3781 OtherOpT = TI->getOperand(0);
3782 OtherOpF = FI->getOperand(1);
3783 MatchIsOpZero = true;
3788 // If we reach here, they do have operations in common.
3789 SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
3790 OtherOpF, SI.getName()+".v");
3791 InsertNewInstBefore(NewSI, SI);
3793 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
3795 return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
3797 return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
3800 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI);
3802 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp);
3806 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
3807 Value *CondVal = SI.getCondition();
3808 Value *TrueVal = SI.getTrueValue();
3809 Value *FalseVal = SI.getFalseValue();
3811 // select true, X, Y -> X
3812 // select false, X, Y -> Y
3813 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
3814 if (C == ConstantBool::True)
3815 return ReplaceInstUsesWith(SI, TrueVal);
3817 assert(C == ConstantBool::False);
3818 return ReplaceInstUsesWith(SI, FalseVal);
3821 // select C, X, X -> X
3822 if (TrueVal == FalseVal)
3823 return ReplaceInstUsesWith(SI, TrueVal);
3825 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
3826 return ReplaceInstUsesWith(SI, FalseVal);
3827 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
3828 return ReplaceInstUsesWith(SI, TrueVal);
3829 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
3830 if (isa<Constant>(TrueVal))
3831 return ReplaceInstUsesWith(SI, TrueVal);
3833 return ReplaceInstUsesWith(SI, FalseVal);
3836 if (SI.getType() == Type::BoolTy)
3837 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
3838 if (C == ConstantBool::True) {
3839 // Change: A = select B, true, C --> A = or B, C
3840 return BinaryOperator::createOr(CondVal, FalseVal);
3842 // Change: A = select B, false, C --> A = and !B, C
3844 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
3845 "not."+CondVal->getName()), SI);
3846 return BinaryOperator::createAnd(NotCond, FalseVal);
3848 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
3849 if (C == ConstantBool::False) {
3850 // Change: A = select B, C, false --> A = and B, C
3851 return BinaryOperator::createAnd(CondVal, TrueVal);
3853 // Change: A = select B, C, true --> A = or !B, C
3855 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
3856 "not."+CondVal->getName()), SI);
3857 return BinaryOperator::createOr(NotCond, TrueVal);
3861 // Selecting between two integer constants?
3862 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
3863 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
3864 // select C, 1, 0 -> cast C to int
3865 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
3866 return new CastInst(CondVal, SI.getType());
3867 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
3868 // select C, 0, 1 -> cast !C to int
3870 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
3871 "not."+CondVal->getName()), SI);
3872 return new CastInst(NotCond, SI.getType());
3875 // If one of the constants is zero (we know they can't both be) and we
3876 // have a setcc instruction with zero, and we have an 'and' with the
3877 // non-constant value, eliminate this whole mess. This corresponds to
3878 // cases like this: ((X & 27) ? 27 : 0)
3879 if (TrueValC->isNullValue() || FalseValC->isNullValue())
3880 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
3881 if ((IC->getOpcode() == Instruction::SetEQ ||
3882 IC->getOpcode() == Instruction::SetNE) &&
3883 isa<ConstantInt>(IC->getOperand(1)) &&
3884 cast<Constant>(IC->getOperand(1))->isNullValue())
3885 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
3886 if (ICA->getOpcode() == Instruction::And &&
3887 isa<ConstantInt>(ICA->getOperand(1)) &&
3888 (ICA->getOperand(1) == TrueValC ||
3889 ICA->getOperand(1) == FalseValC) &&
3890 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
3891 // Okay, now we know that everything is set up, we just don't
3892 // know whether we have a setne or seteq and whether the true or
3893 // false val is the zero.
3894 bool ShouldNotVal = !TrueValC->isNullValue();
3895 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
3898 V = InsertNewInstBefore(BinaryOperator::create(
3899 Instruction::Xor, V, ICA->getOperand(1)), SI);
3900 return ReplaceInstUsesWith(SI, V);
3904 // See if we are selecting two values based on a comparison of the two values.
3905 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
3906 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
3907 // Transform (X == Y) ? X : Y -> Y
3908 if (SCI->getOpcode() == Instruction::SetEQ)
3909 return ReplaceInstUsesWith(SI, FalseVal);
3910 // Transform (X != Y) ? X : Y -> X
3911 if (SCI->getOpcode() == Instruction::SetNE)
3912 return ReplaceInstUsesWith(SI, TrueVal);
3913 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
3915 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
3916 // Transform (X == Y) ? Y : X -> X
3917 if (SCI->getOpcode() == Instruction::SetEQ)
3918 return ReplaceInstUsesWith(SI, FalseVal);
3919 // Transform (X != Y) ? Y : X -> Y
3920 if (SCI->getOpcode() == Instruction::SetNE)
3921 return ReplaceInstUsesWith(SI, TrueVal);
3922 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
3926 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
3927 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
3928 if (TI->hasOneUse() && FI->hasOneUse()) {
3929 bool isInverse = false;
3930 Instruction *AddOp = 0, *SubOp = 0;
3932 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
3933 if (TI->getOpcode() == FI->getOpcode())
3934 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
3937 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
3938 // even legal for FP.
3939 if (TI->getOpcode() == Instruction::Sub &&
3940 FI->getOpcode() == Instruction::Add) {
3941 AddOp = FI; SubOp = TI;
3942 } else if (FI->getOpcode() == Instruction::Sub &&
3943 TI->getOpcode() == Instruction::Add) {
3944 AddOp = TI; SubOp = FI;
3948 Value *OtherAddOp = 0;
3949 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
3950 OtherAddOp = AddOp->getOperand(1);
3951 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
3952 OtherAddOp = AddOp->getOperand(0);
3956 // So at this point we know we have:
3957 // select C, (add X, Y), (sub X, ?)
3958 // We can do the transform profitably if either 'Y' = '?' or '?' is
3960 if (SubOp->getOperand(1) == AddOp ||
3961 isa<Constant>(SubOp->getOperand(1))) {
3963 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
3964 NegVal = ConstantExpr::getNeg(C);
3966 NegVal = InsertNewInstBefore(
3967 BinaryOperator::createNeg(SubOp->getOperand(1)), SI);
3970 Value *NewTrueOp = OtherAddOp;
3971 Value *NewFalseOp = NegVal;
3973 std::swap(NewTrueOp, NewFalseOp);
3974 Instruction *NewSel =
3975 new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
3977 NewSel = InsertNewInstBefore(NewSel, SI);
3978 return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
3984 // See if we can fold the select into one of our operands.
3985 if (SI.getType()->isInteger()) {
3986 // See the comment above GetSelectFoldableOperands for a description of the
3987 // transformation we are doing here.
3988 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
3989 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
3990 !isa<Constant>(FalseVal))
3991 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
3992 unsigned OpToFold = 0;
3993 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
3995 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
4000 Constant *C = GetSelectFoldableConstant(TVI);
4001 std::string Name = TVI->getName(); TVI->setName("");
4002 Instruction *NewSel =
4003 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
4005 InsertNewInstBefore(NewSel, SI);
4006 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
4007 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
4008 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
4009 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
4011 assert(0 && "Unknown instruction!!");
4016 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
4017 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
4018 !isa<Constant>(TrueVal))
4019 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
4020 unsigned OpToFold = 0;
4021 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
4023 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
4028 Constant *C = GetSelectFoldableConstant(FVI);
4029 std::string Name = FVI->getName(); FVI->setName("");
4030 Instruction *NewSel =
4031 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
4033 InsertNewInstBefore(NewSel, SI);
4034 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
4035 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
4036 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
4037 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
4039 assert(0 && "Unknown instruction!!");
4045 if (BinaryOperator::isNot(CondVal)) {
4046 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
4047 SI.setOperand(1, FalseVal);
4048 SI.setOperand(2, TrueVal);
4056 // CallInst simplification
4058 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
4059 // Intrinsics cannot occur in an invoke, so handle them here instead of in
4061 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(&CI)) {
4062 bool Changed = false;
4064 // memmove/cpy/set of zero bytes is a noop.
4065 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
4066 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
4068 // FIXME: Increase alignment here.
4070 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
4071 if (CI->getRawValue() == 1) {
4072 // Replace the instruction with just byte operations. We would
4073 // transform other cases to loads/stores, but we don't know if
4074 // alignment is sufficient.
4078 // If we have a memmove and the source operation is a constant global,
4079 // then the source and dest pointers can't alias, so we can change this
4080 // into a call to memcpy.
4081 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI))
4082 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
4083 if (GVSrc->isConstant()) {
4084 Module *M = CI.getParent()->getParent()->getParent();
4085 Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
4086 CI.getCalledFunction()->getFunctionType());
4087 CI.setOperand(0, MemCpy);
4091 if (Changed) return &CI;
4092 } else if (DbgStopPointInst *SPI = dyn_cast<DbgStopPointInst>(&CI)) {
4093 // If this stoppoint is at the same source location as the previous
4094 // stoppoint in the chain, it is not needed.
4095 if (DbgStopPointInst *PrevSPI =
4096 dyn_cast<DbgStopPointInst>(SPI->getChain()))
4097 if (SPI->getLineNo() == PrevSPI->getLineNo() &&
4098 SPI->getColNo() == PrevSPI->getColNo()) {
4099 SPI->replaceAllUsesWith(PrevSPI);
4100 return EraseInstFromFunction(CI);
4104 return visitCallSite(&CI);
4107 // InvokeInst simplification
4109 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
4110 return visitCallSite(&II);
4113 // visitCallSite - Improvements for call and invoke instructions.
4115 Instruction *InstCombiner::visitCallSite(CallSite CS) {
4116 bool Changed = false;
4118 // If the callee is a constexpr cast of a function, attempt to move the cast
4119 // to the arguments of the call/invoke.
4120 if (transformConstExprCastCall(CS)) return 0;
4122 Value *Callee = CS.getCalledValue();
4124 if (Function *CalleeF = dyn_cast<Function>(Callee))
4125 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
4126 Instruction *OldCall = CS.getInstruction();
4127 // If the call and callee calling conventions don't match, this call must
4128 // be unreachable, as the call is undefined.
4129 new StoreInst(ConstantBool::True,
4130 UndefValue::get(PointerType::get(Type::BoolTy)), OldCall);
4131 if (!OldCall->use_empty())
4132 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
4133 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
4134 return EraseInstFromFunction(*OldCall);
4138 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
4139 // This instruction is not reachable, just remove it. We insert a store to
4140 // undef so that we know that this code is not reachable, despite the fact
4141 // that we can't modify the CFG here.
4142 new StoreInst(ConstantBool::True,
4143 UndefValue::get(PointerType::get(Type::BoolTy)),
4144 CS.getInstruction());
4146 if (!CS.getInstruction()->use_empty())
4147 CS.getInstruction()->
4148 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
4150 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
4151 // Don't break the CFG, insert a dummy cond branch.
4152 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
4153 ConstantBool::True, II);
4155 return EraseInstFromFunction(*CS.getInstruction());
4158 const PointerType *PTy = cast<PointerType>(Callee->getType());
4159 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
4160 if (FTy->isVarArg()) {
4161 // See if we can optimize any arguments passed through the varargs area of
4163 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
4164 E = CS.arg_end(); I != E; ++I)
4165 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
4166 // If this cast does not effect the value passed through the varargs
4167 // area, we can eliminate the use of the cast.
4168 Value *Op = CI->getOperand(0);
4169 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
4176 return Changed ? CS.getInstruction() : 0;
4179 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
4180 // attempt to move the cast to the arguments of the call/invoke.
4182 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
4183 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
4184 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
4185 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
4187 Function *Callee = cast<Function>(CE->getOperand(0));
4188 Instruction *Caller = CS.getInstruction();
4190 // Okay, this is a cast from a function to a different type. Unless doing so
4191 // would cause a type conversion of one of our arguments, change this call to
4192 // be a direct call with arguments casted to the appropriate types.
4194 const FunctionType *FT = Callee->getFunctionType();
4195 const Type *OldRetTy = Caller->getType();
4197 // Check to see if we are changing the return type...
4198 if (OldRetTy != FT->getReturnType()) {
4199 if (Callee->isExternal() &&
4200 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
4201 !Caller->use_empty())
4202 return false; // Cannot transform this return value...
4204 // If the callsite is an invoke instruction, and the return value is used by
4205 // a PHI node in a successor, we cannot change the return type of the call
4206 // because there is no place to put the cast instruction (without breaking
4207 // the critical edge). Bail out in this case.
4208 if (!Caller->use_empty())
4209 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
4210 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
4212 if (PHINode *PN = dyn_cast<PHINode>(*UI))
4213 if (PN->getParent() == II->getNormalDest() ||
4214 PN->getParent() == II->getUnwindDest())
4218 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
4219 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
4221 CallSite::arg_iterator AI = CS.arg_begin();
4222 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
4223 const Type *ParamTy = FT->getParamType(i);
4224 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
4225 if (Callee->isExternal() && !isConvertible) return false;
4228 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
4229 Callee->isExternal())
4230 return false; // Do not delete arguments unless we have a function body...
4232 // Okay, we decided that this is a safe thing to do: go ahead and start
4233 // inserting cast instructions as necessary...
4234 std::vector<Value*> Args;
4235 Args.reserve(NumActualArgs);
4237 AI = CS.arg_begin();
4238 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
4239 const Type *ParamTy = FT->getParamType(i);
4240 if ((*AI)->getType() == ParamTy) {
4241 Args.push_back(*AI);
4243 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
4248 // If the function takes more arguments than the call was taking, add them
4250 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
4251 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
4253 // If we are removing arguments to the function, emit an obnoxious warning...
4254 if (FT->getNumParams() < NumActualArgs)
4255 if (!FT->isVarArg()) {
4256 std::cerr << "WARNING: While resolving call to function '"
4257 << Callee->getName() << "' arguments were dropped!\n";
4259 // Add all of the arguments in their promoted form to the arg list...
4260 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
4261 const Type *PTy = getPromotedType((*AI)->getType());
4262 if (PTy != (*AI)->getType()) {
4263 // Must promote to pass through va_arg area!
4264 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
4265 InsertNewInstBefore(Cast, *Caller);
4266 Args.push_back(Cast);
4268 Args.push_back(*AI);
4273 if (FT->getReturnType() == Type::VoidTy)
4274 Caller->setName(""); // Void type should not have a name...
4277 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4278 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
4279 Args, Caller->getName(), Caller);
4280 cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
4282 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
4283 if (cast<CallInst>(Caller)->isTailCall())
4284 cast<CallInst>(NC)->setTailCall();
4285 cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
4288 // Insert a cast of the return type as necessary...
4290 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
4291 if (NV->getType() != Type::VoidTy) {
4292 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
4294 // If this is an invoke instruction, we should insert it after the first
4295 // non-phi, instruction in the normal successor block.
4296 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4297 BasicBlock::iterator I = II->getNormalDest()->begin();
4298 while (isa<PHINode>(I)) ++I;
4299 InsertNewInstBefore(NC, *I);
4301 // Otherwise, it's a call, just insert cast right after the call instr
4302 InsertNewInstBefore(NC, *Caller);
4304 AddUsersToWorkList(*Caller);
4306 NV = UndefValue::get(Caller->getType());
4310 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
4311 Caller->replaceAllUsesWith(NV);
4312 Caller->getParent()->getInstList().erase(Caller);
4313 removeFromWorkList(Caller);
4318 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
4319 // operator and they all are only used by the PHI, PHI together their
4320 // inputs, and do the operation once, to the result of the PHI.
4321 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
4322 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
4324 // Scan the instruction, looking for input operations that can be folded away.
4325 // If all input operands to the phi are the same instruction (e.g. a cast from
4326 // the same type or "+42") we can pull the operation through the PHI, reducing
4327 // code size and simplifying code.
4328 Constant *ConstantOp = 0;
4329 const Type *CastSrcTy = 0;
4330 if (isa<CastInst>(FirstInst)) {
4331 CastSrcTy = FirstInst->getOperand(0)->getType();
4332 } else if (isa<BinaryOperator>(FirstInst) || isa<ShiftInst>(FirstInst)) {
4333 // Can fold binop or shift if the RHS is a constant.
4334 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
4335 if (ConstantOp == 0) return 0;
4337 return 0; // Cannot fold this operation.
4340 // Check to see if all arguments are the same operation.
4341 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4342 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
4343 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
4344 if (!I->hasOneUse() || I->getOpcode() != FirstInst->getOpcode())
4347 if (I->getOperand(0)->getType() != CastSrcTy)
4348 return 0; // Cast operation must match.
4349 } else if (I->getOperand(1) != ConstantOp) {
4354 // Okay, they are all the same operation. Create a new PHI node of the
4355 // correct type, and PHI together all of the LHS's of the instructions.
4356 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
4357 PN.getName()+".in");
4358 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
4360 Value *InVal = FirstInst->getOperand(0);
4361 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
4363 // Add all operands to the new PHI.
4364 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4365 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
4366 if (NewInVal != InVal)
4368 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
4373 // The new PHI unions all of the same values together. This is really
4374 // common, so we handle it intelligently here for compile-time speed.
4378 InsertNewInstBefore(NewPN, PN);
4382 // Insert and return the new operation.
4383 if (isa<CastInst>(FirstInst))
4384 return new CastInst(PhiVal, PN.getType());
4385 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
4386 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
4388 return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(),
4389 PhiVal, ConstantOp);
4392 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
4394 static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &PotentiallyDeadPHIs) {
4395 if (PN->use_empty()) return true;
4396 if (!PN->hasOneUse()) return false;
4398 // Remember this node, and if we find the cycle, return.
4399 if (!PotentiallyDeadPHIs.insert(PN).second)
4402 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
4403 return DeadPHICycle(PU, PotentiallyDeadPHIs);
4408 // PHINode simplification
4410 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
4411 if (Value *V = hasConstantValue(&PN)) {
4412 // If V is an instruction, we have to be certain that it dominates PN.
4413 // However, because we don't have dom info, we can't do a perfect job.
4414 if (Instruction *I = dyn_cast<Instruction>(V)) {
4415 // We know that the instruction dominates the PHI if there are no undef
4416 // values coming in. If the instruction is defined in the entry block,
4417 // and is not an invoke, we know it is ok.
4418 if (I->getParent() != &I->getParent()->getParent()->front() ||
4420 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
4421 if (isa<UndefValue>(PN.getIncomingValue(i))) {
4428 return ReplaceInstUsesWith(PN, V);
4431 // If the only user of this instruction is a cast instruction, and all of the
4432 // incoming values are constants, change this PHI to merge together the casted
4435 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
4436 if (CI->getType() != PN.getType()) { // noop casts will be folded
4437 bool AllConstant = true;
4438 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
4439 if (!isa<Constant>(PN.getIncomingValue(i))) {
4440 AllConstant = false;
4444 // Make a new PHI with all casted values.
4445 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
4446 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
4447 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
4448 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
4449 PN.getIncomingBlock(i));
4452 // Update the cast instruction.
4453 CI->setOperand(0, New);
4454 WorkList.push_back(CI); // revisit the cast instruction to fold.
4455 WorkList.push_back(New); // Make sure to revisit the new Phi
4456 return &PN; // PN is now dead!
4460 // If all PHI operands are the same operation, pull them through the PHI,
4461 // reducing code size.
4462 if (isa<Instruction>(PN.getIncomingValue(0)) &&
4463 PN.getIncomingValue(0)->hasOneUse())
4464 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
4467 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
4468 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
4469 // PHI)... break the cycle.
4471 if (PHINode *PU = dyn_cast<PHINode>(PN.use_back())) {
4472 std::set<PHINode*> PotentiallyDeadPHIs;
4473 PotentiallyDeadPHIs.insert(&PN);
4474 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
4475 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
4481 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
4482 Instruction *InsertPoint,
4484 unsigned PS = IC->getTargetData().getPointerSize();
4485 const Type *VTy = V->getType();
4486 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
4487 // We must insert a cast to ensure we sign-extend.
4488 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
4489 V->getName()), *InsertPoint);
4490 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
4495 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
4496 Value *PtrOp = GEP.getOperand(0);
4497 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
4498 // If so, eliminate the noop.
4499 if (GEP.getNumOperands() == 1)
4500 return ReplaceInstUsesWith(GEP, PtrOp);
4502 if (isa<UndefValue>(GEP.getOperand(0)))
4503 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
4505 bool HasZeroPointerIndex = false;
4506 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
4507 HasZeroPointerIndex = C->isNullValue();
4509 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
4510 return ReplaceInstUsesWith(GEP, PtrOp);
4512 // Eliminate unneeded casts for indices.
4513 bool MadeChange = false;
4514 gep_type_iterator GTI = gep_type_begin(GEP);
4515 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
4516 if (isa<SequentialType>(*GTI)) {
4517 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
4518 Value *Src = CI->getOperand(0);
4519 const Type *SrcTy = Src->getType();
4520 const Type *DestTy = CI->getType();
4521 if (Src->getType()->isInteger()) {
4522 if (SrcTy->getPrimitiveSizeInBits() ==
4523 DestTy->getPrimitiveSizeInBits()) {
4524 // We can always eliminate a cast from ulong or long to the other.
4525 // We can always eliminate a cast from uint to int or the other on
4526 // 32-bit pointer platforms.
4527 if (DestTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()){
4529 GEP.setOperand(i, Src);
4531 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
4532 SrcTy->getPrimitiveSize() == 4) {
4533 // We can always eliminate a cast from int to [u]long. We can
4534 // eliminate a cast from uint to [u]long iff the target is a 32-bit
4536 if (SrcTy->isSigned() ||
4537 SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
4539 GEP.setOperand(i, Src);
4544 // If we are using a wider index than needed for this platform, shrink it
4545 // to what we need. If the incoming value needs a cast instruction,
4546 // insert it. This explicit cast can make subsequent optimizations more
4548 Value *Op = GEP.getOperand(i);
4549 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
4550 if (Constant *C = dyn_cast<Constant>(Op)) {
4551 GEP.setOperand(i, ConstantExpr::getCast(C,
4552 TD->getIntPtrType()->getSignedVersion()));
4555 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
4556 Op->getName()), GEP);
4557 GEP.setOperand(i, Op);
4561 // If this is a constant idx, make sure to canonicalize it to be a signed
4562 // operand, otherwise CSE and other optimizations are pessimized.
4563 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
4564 GEP.setOperand(i, ConstantExpr::getCast(CUI,
4565 CUI->getType()->getSignedVersion()));
4569 if (MadeChange) return &GEP;
4571 // Combine Indices - If the source pointer to this getelementptr instruction
4572 // is a getelementptr instruction, combine the indices of the two
4573 // getelementptr instructions into a single instruction.
4575 std::vector<Value*> SrcGEPOperands;
4576 if (User *Src = dyn_castGetElementPtr(PtrOp))
4577 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
4579 if (!SrcGEPOperands.empty()) {
4580 // Note that if our source is a gep chain itself that we wait for that
4581 // chain to be resolved before we perform this transformation. This
4582 // avoids us creating a TON of code in some cases.
4584 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
4585 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
4586 return 0; // Wait until our source is folded to completion.
4588 std::vector<Value *> Indices;
4590 // Find out whether the last index in the source GEP is a sequential idx.
4591 bool EndsWithSequential = false;
4592 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
4593 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
4594 EndsWithSequential = !isa<StructType>(*I);
4596 // Can we combine the two pointer arithmetics offsets?
4597 if (EndsWithSequential) {
4598 // Replace: gep (gep %P, long B), long A, ...
4599 // With: T = long A+B; gep %P, T, ...
4601 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
4602 if (SO1 == Constant::getNullValue(SO1->getType())) {
4604 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
4607 // If they aren't the same type, convert both to an integer of the
4608 // target's pointer size.
4609 if (SO1->getType() != GO1->getType()) {
4610 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
4611 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
4612 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
4613 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
4615 unsigned PS = TD->getPointerSize();
4616 if (SO1->getType()->getPrimitiveSize() == PS) {
4617 // Convert GO1 to SO1's type.
4618 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
4620 } else if (GO1->getType()->getPrimitiveSize() == PS) {
4621 // Convert SO1 to GO1's type.
4622 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
4624 const Type *PT = TD->getIntPtrType();
4625 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
4626 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
4630 if (isa<Constant>(SO1) && isa<Constant>(GO1))
4631 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
4633 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
4634 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
4638 // Recycle the GEP we already have if possible.
4639 if (SrcGEPOperands.size() == 2) {
4640 GEP.setOperand(0, SrcGEPOperands[0]);
4641 GEP.setOperand(1, Sum);
4644 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
4645 SrcGEPOperands.end()-1);
4646 Indices.push_back(Sum);
4647 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
4649 } else if (isa<Constant>(*GEP.idx_begin()) &&
4650 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
4651 SrcGEPOperands.size() != 1) {
4652 // Otherwise we can do the fold if the first index of the GEP is a zero
4653 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
4654 SrcGEPOperands.end());
4655 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
4658 if (!Indices.empty())
4659 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
4661 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
4662 // GEP of global variable. If all of the indices for this GEP are
4663 // constants, we can promote this to a constexpr instead of an instruction.
4665 // Scan for nonconstants...
4666 std::vector<Constant*> Indices;
4667 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
4668 for (; I != E && isa<Constant>(*I); ++I)
4669 Indices.push_back(cast<Constant>(*I));
4671 if (I == E) { // If they are all constants...
4672 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
4674 // Replace all uses of the GEP with the new constexpr...
4675 return ReplaceInstUsesWith(GEP, CE);
4677 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(PtrOp)) {
4678 if (CE->getOpcode() == Instruction::Cast) {
4679 if (HasZeroPointerIndex) {
4680 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
4681 // into : GEP [10 x ubyte]* X, long 0, ...
4683 // This occurs when the program declares an array extern like "int X[];"
4685 Constant *X = CE->getOperand(0);
4686 const PointerType *CPTy = cast<PointerType>(CE->getType());
4687 if (const PointerType *XTy = dyn_cast<PointerType>(X->getType()))
4688 if (const ArrayType *XATy =
4689 dyn_cast<ArrayType>(XTy->getElementType()))
4690 if (const ArrayType *CATy =
4691 dyn_cast<ArrayType>(CPTy->getElementType()))
4692 if (CATy->getElementType() == XATy->getElementType()) {
4693 // At this point, we know that the cast source type is a pointer
4694 // to an array of the same type as the destination pointer
4695 // array. Because the array type is never stepped over (there
4696 // is a leading zero) we can fold the cast into this GEP.
4697 GEP.setOperand(0, X);
4700 } else if (GEP.getNumOperands() == 2 &&
4701 isa<PointerType>(CE->getOperand(0)->getType())) {
4702 // Transform things like:
4703 // %t = getelementptr ubyte* cast ([2 x sbyte]* %str to ubyte*), uint %V
4704 // into: %t1 = getelementptr [2 x sbyte*]* %str, int 0, uint %V; cast
4705 Constant *X = CE->getOperand(0);
4706 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
4707 const Type *ResElTy =cast<PointerType>(CE->getType())->getElementType();
4708 if (isa<ArrayType>(SrcElTy) &&
4709 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
4710 TD->getTypeSize(ResElTy)) {
4711 Value *V = InsertNewInstBefore(
4712 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
4713 GEP.getOperand(1), GEP.getName()), GEP);
4714 return new CastInst(V, GEP.getType());
4723 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
4724 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
4725 if (AI.isArrayAllocation()) // Check C != 1
4726 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
4727 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
4728 AllocationInst *New = 0;
4730 // Create and insert the replacement instruction...
4731 if (isa<MallocInst>(AI))
4732 New = new MallocInst(NewTy, 0, AI.getName());
4734 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
4735 New = new AllocaInst(NewTy, 0, AI.getName());
4738 InsertNewInstBefore(New, AI);
4740 // Scan to the end of the allocation instructions, to skip over a block of
4741 // allocas if possible...
4743 BasicBlock::iterator It = New;
4744 while (isa<AllocationInst>(*It)) ++It;
4746 // Now that I is pointing to the first non-allocation-inst in the block,
4747 // insert our getelementptr instruction...
4749 Value *NullIdx = Constant::getNullValue(Type::IntTy);
4750 Value *V = new GetElementPtrInst(New, NullIdx, NullIdx,
4751 New->getName()+".sub", It);
4753 // Now make everything use the getelementptr instead of the original
4755 return ReplaceInstUsesWith(AI, V);
4756 } else if (isa<UndefValue>(AI.getArraySize())) {
4757 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
4760 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
4761 // Note that we only do this for alloca's, because malloc should allocate and
4762 // return a unique pointer, even for a zero byte allocation.
4763 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
4764 TD->getTypeSize(AI.getAllocatedType()) == 0)
4765 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
4770 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
4771 Value *Op = FI.getOperand(0);
4773 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
4774 if (CastInst *CI = dyn_cast<CastInst>(Op))
4775 if (isa<PointerType>(CI->getOperand(0)->getType())) {
4776 FI.setOperand(0, CI->getOperand(0));
4780 // free undef -> unreachable.
4781 if (isa<UndefValue>(Op)) {
4782 // Insert a new store to null because we cannot modify the CFG here.
4783 new StoreInst(ConstantBool::True,
4784 UndefValue::get(PointerType::get(Type::BoolTy)), &FI);
4785 return EraseInstFromFunction(FI);
4788 // If we have 'free null' delete the instruction. This can happen in stl code
4789 // when lots of inlining happens.
4790 if (isa<ConstantPointerNull>(Op))
4791 return EraseInstFromFunction(FI);
4797 /// GetGEPGlobalInitializer - Given a constant, and a getelementptr
4798 /// constantexpr, return the constant value being addressed by the constant
4799 /// expression, or null if something is funny.
4801 static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
4802 if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
4803 return 0; // Do not allow stepping over the value!
4805 // Loop over all of the operands, tracking down which value we are
4807 gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
4808 for (++I; I != E; ++I)
4809 if (const StructType *STy = dyn_cast<StructType>(*I)) {
4810 ConstantUInt *CU = cast<ConstantUInt>(I.getOperand());
4811 assert(CU->getValue() < STy->getNumElements() &&
4812 "Struct index out of range!");
4813 unsigned El = (unsigned)CU->getValue();
4814 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
4815 C = CS->getOperand(El);
4816 } else if (isa<ConstantAggregateZero>(C)) {
4817 C = Constant::getNullValue(STy->getElementType(El));
4818 } else if (isa<UndefValue>(C)) {
4819 C = UndefValue::get(STy->getElementType(El));
4823 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
4824 const ArrayType *ATy = cast<ArrayType>(*I);
4825 if ((uint64_t)CI->getRawValue() >= ATy->getNumElements()) return 0;
4826 if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
4827 C = CA->getOperand((unsigned)CI->getRawValue());
4828 else if (isa<ConstantAggregateZero>(C))
4829 C = Constant::getNullValue(ATy->getElementType());
4830 else if (isa<UndefValue>(C))
4831 C = UndefValue::get(ATy->getElementType());
4840 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
4841 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
4842 User *CI = cast<User>(LI.getOperand(0));
4843 Value *CastOp = CI->getOperand(0);
4845 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
4846 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
4847 const Type *SrcPTy = SrcTy->getElementType();
4849 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
4850 // If the source is an array, the code below will not succeed. Check to
4851 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
4853 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
4854 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
4855 if (ASrcTy->getNumElements() != 0) {
4856 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
4857 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
4858 SrcTy = cast<PointerType>(CastOp->getType());
4859 SrcPTy = SrcTy->getElementType();
4862 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
4863 // Do not allow turning this into a load of an integer, which is then
4864 // casted to a pointer, this pessimizes pointer analysis a lot.
4865 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
4866 IC.getTargetData().getTypeSize(SrcPTy) ==
4867 IC.getTargetData().getTypeSize(DestPTy)) {
4869 // Okay, we are casting from one integer or pointer type to another of
4870 // the same size. Instead of casting the pointer before the load, cast
4871 // the result of the loaded value.
4872 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
4874 LI.isVolatile()),LI);
4875 // Now cast the result of the load.
4876 return new CastInst(NewLoad, LI.getType());
4883 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
4884 /// from this value cannot trap. If it is not obviously safe to load from the
4885 /// specified pointer, we do a quick local scan of the basic block containing
4886 /// ScanFrom, to determine if the address is already accessed.
4887 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
4888 // If it is an alloca or global variable, it is always safe to load from.
4889 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
4891 // Otherwise, be a little bit agressive by scanning the local block where we
4892 // want to check to see if the pointer is already being loaded or stored
4893 // from/to. If so, the previous load or store would have already trapped,
4894 // so there is no harm doing an extra load (also, CSE will later eliminate
4895 // the load entirely).
4896 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
4901 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
4902 if (LI->getOperand(0) == V) return true;
4903 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
4904 if (SI->getOperand(1) == V) return true;
4910 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
4911 Value *Op = LI.getOperand(0);
4913 // load (cast X) --> cast (load X) iff safe
4914 if (CastInst *CI = dyn_cast<CastInst>(Op))
4915 if (Instruction *Res = InstCombineLoadCast(*this, LI))
4918 // None of the following transforms are legal for volatile loads.
4919 if (LI.isVolatile()) return 0;
4921 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
4922 if (isa<ConstantPointerNull>(GEPI->getOperand(0)) ||
4923 isa<UndefValue>(GEPI->getOperand(0))) {
4924 // Insert a new store to null instruction before the load to indicate
4925 // that this code is not reachable. We do this instead of inserting
4926 // an unreachable instruction directly because we cannot modify the
4928 new StoreInst(UndefValue::get(LI.getType()),
4929 Constant::getNullValue(Op->getType()), &LI);
4930 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
4933 if (Constant *C = dyn_cast<Constant>(Op)) {
4934 // load null/undef -> undef
4935 if ((C->isNullValue() || isa<UndefValue>(C))) {
4936 // Insert a new store to null instruction before the load to indicate that
4937 // this code is not reachable. We do this instead of inserting an
4938 // unreachable instruction directly because we cannot modify the CFG.
4939 new StoreInst(UndefValue::get(LI.getType()),
4940 Constant::getNullValue(Op->getType()), &LI);
4941 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
4944 // Instcombine load (constant global) into the value loaded.
4945 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
4946 if (GV->isConstant() && !GV->isExternal())
4947 return ReplaceInstUsesWith(LI, GV->getInitializer());
4949 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
4950 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
4951 if (CE->getOpcode() == Instruction::GetElementPtr) {
4952 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
4953 if (GV->isConstant() && !GV->isExternal())
4954 if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
4955 return ReplaceInstUsesWith(LI, V);
4956 if (CE->getOperand(0)->isNullValue()) {
4957 // Insert a new store to null instruction before the load to indicate
4958 // that this code is not reachable. We do this instead of inserting
4959 // an unreachable instruction directly because we cannot modify the
4961 new StoreInst(UndefValue::get(LI.getType()),
4962 Constant::getNullValue(Op->getType()), &LI);
4963 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
4966 } else if (CE->getOpcode() == Instruction::Cast) {
4967 if (Instruction *Res = InstCombineLoadCast(*this, LI))
4972 if (Op->hasOneUse()) {
4973 // Change select and PHI nodes to select values instead of addresses: this
4974 // helps alias analysis out a lot, allows many others simplifications, and
4975 // exposes redundancy in the code.
4977 // Note that we cannot do the transformation unless we know that the
4978 // introduced loads cannot trap! Something like this is valid as long as
4979 // the condition is always false: load (select bool %C, int* null, int* %G),
4980 // but it would not be valid if we transformed it to load from null
4983 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
4984 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
4985 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
4986 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
4987 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
4988 SI->getOperand(1)->getName()+".val"), LI);
4989 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
4990 SI->getOperand(2)->getName()+".val"), LI);
4991 return new SelectInst(SI->getCondition(), V1, V2);
4994 // load (select (cond, null, P)) -> load P
4995 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
4996 if (C->isNullValue()) {
4997 LI.setOperand(0, SI->getOperand(2));
5001 // load (select (cond, P, null)) -> load P
5002 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
5003 if (C->isNullValue()) {
5004 LI.setOperand(0, SI->getOperand(1));
5008 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
5009 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
5010 bool Safe = PN->getParent() == LI.getParent();
5012 // Scan all of the instructions between the PHI and the load to make
5013 // sure there are no instructions that might possibly alter the value
5014 // loaded from the PHI.
5016 BasicBlock::iterator I = &LI;
5017 for (--I; !isa<PHINode>(I); --I)
5018 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
5024 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
5025 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
5026 PN->getIncomingBlock(i)->getTerminator()))
5031 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
5032 InsertNewInstBefore(NewPN, *PN);
5033 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
5035 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
5036 BasicBlock *BB = PN->getIncomingBlock(i);
5037 Value *&TheLoad = LoadMap[BB];
5039 Value *InVal = PN->getIncomingValue(i);
5040 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
5041 InVal->getName()+".val"),
5042 *BB->getTerminator());
5044 NewPN->addIncoming(TheLoad, BB);
5046 return ReplaceInstUsesWith(LI, NewPN);
5053 /// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store (cast V), P'
5055 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
5056 User *CI = cast<User>(SI.getOperand(1));
5057 Value *CastOp = CI->getOperand(0);
5059 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5060 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5061 const Type *SrcPTy = SrcTy->getElementType();
5063 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5064 // If the source is an array, the code below will not succeed. Check to
5065 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5067 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5068 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5069 if (ASrcTy->getNumElements() != 0) {
5070 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5071 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5072 SrcTy = cast<PointerType>(CastOp->getType());
5073 SrcPTy = SrcTy->getElementType();
5076 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5077 IC.getTargetData().getTypeSize(SrcPTy) ==
5078 IC.getTargetData().getTypeSize(DestPTy)) {
5080 // Okay, we are casting from one integer or pointer type to another of
5081 // the same size. Instead of casting the pointer before the store, cast
5082 // the value to be stored.
5084 if (Constant *C = dyn_cast<Constant>(SI.getOperand(0)))
5085 NewCast = ConstantExpr::getCast(C, SrcPTy);
5087 NewCast = IC.InsertNewInstBefore(new CastInst(SI.getOperand(0),
5089 SI.getOperand(0)->getName()+".c"), SI);
5091 return new StoreInst(NewCast, CastOp);
5098 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
5099 Value *Val = SI.getOperand(0);
5100 Value *Ptr = SI.getOperand(1);
5102 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
5103 removeFromWorkList(&SI);
5104 SI.eraseFromParent();
5109 if (SI.isVolatile()) return 0; // Don't hack volatile loads.
5111 // store X, null -> turns into 'unreachable' in SimplifyCFG
5112 if (isa<ConstantPointerNull>(Ptr)) {
5113 if (!isa<UndefValue>(Val)) {
5114 SI.setOperand(0, UndefValue::get(Val->getType()));
5115 if (Instruction *U = dyn_cast<Instruction>(Val))
5116 WorkList.push_back(U); // Dropped a use.
5119 return 0; // Do not modify these!
5122 // store undef, Ptr -> noop
5123 if (isa<UndefValue>(Val)) {
5124 removeFromWorkList(&SI);
5125 SI.eraseFromParent();
5130 // If the pointer destination is a cast, see if we can fold the cast into the
5132 if (CastInst *CI = dyn_cast<CastInst>(Ptr))
5133 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5135 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
5136 if (CE->getOpcode() == Instruction::Cast)
5137 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5144 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
5145 // Change br (not X), label True, label False to: br X, label False, True
5147 BasicBlock *TrueDest;
5148 BasicBlock *FalseDest;
5149 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
5150 !isa<Constant>(X)) {
5151 // Swap Destinations and condition...
5153 BI.setSuccessor(0, FalseDest);
5154 BI.setSuccessor(1, TrueDest);
5158 // Cannonicalize setne -> seteq
5159 Instruction::BinaryOps Op; Value *Y;
5160 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
5161 TrueDest, FalseDest)))
5162 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
5163 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
5164 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
5165 std::string Name = I->getName(); I->setName("");
5166 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
5167 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
5168 // Swap Destinations and condition...
5169 BI.setCondition(NewSCC);
5170 BI.setSuccessor(0, FalseDest);
5171 BI.setSuccessor(1, TrueDest);
5172 removeFromWorkList(I);
5173 I->getParent()->getInstList().erase(I);
5174 WorkList.push_back(cast<Instruction>(NewSCC));
5181 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
5182 Value *Cond = SI.getCondition();
5183 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
5184 if (I->getOpcode() == Instruction::Add)
5185 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
5186 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
5187 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
5188 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
5190 SI.setOperand(0, I->getOperand(0));
5191 WorkList.push_back(I);
5199 void InstCombiner::removeFromWorkList(Instruction *I) {
5200 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
5205 /// TryToSinkInstruction - Try to move the specified instruction from its
5206 /// current block into the beginning of DestBlock, which can only happen if it's
5207 /// safe to move the instruction past all of the instructions between it and the
5208 /// end of its block.
5209 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
5210 assert(I->hasOneUse() && "Invariants didn't hold!");
5212 // Cannot move control-flow-involving instructions.
5213 if (isa<PHINode>(I) || isa<InvokeInst>(I) || isa<CallInst>(I)) return false;
5215 // Do not sink alloca instructions out of the entry block.
5216 if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front())
5219 // We can only sink load instructions if there is nothing between the load and
5220 // the end of block that could change the value.
5221 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
5222 if (LI->isVolatile()) return false; // Don't sink volatile loads.
5224 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
5226 if (Scan->mayWriteToMemory())
5230 BasicBlock::iterator InsertPos = DestBlock->begin();
5231 while (isa<PHINode>(InsertPos)) ++InsertPos;
5233 BasicBlock *SrcBlock = I->getParent();
5234 DestBlock->getInstList().splice(InsertPos, SrcBlock->getInstList(), I);
5239 bool InstCombiner::runOnFunction(Function &F) {
5240 bool Changed = false;
5241 TD = &getAnalysis<TargetData>();
5244 // Populate the worklist with the reachable instructions.
5245 std::set<BasicBlock*> Visited;
5246 for (df_ext_iterator<BasicBlock*> BB = df_ext_begin(&F.front(), Visited),
5247 E = df_ext_end(&F.front(), Visited); BB != E; ++BB)
5248 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
5249 WorkList.push_back(I);
5251 // Do a quick scan over the function. If we find any blocks that are
5252 // unreachable, remove any instructions inside of them. This prevents
5253 // the instcombine code from having to deal with some bad special cases.
5254 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
5255 if (!Visited.count(BB)) {
5256 Instruction *Term = BB->getTerminator();
5257 while (Term != BB->begin()) { // Remove instrs bottom-up
5258 BasicBlock::iterator I = Term; --I;
5260 DEBUG(std::cerr << "IC: DCE: " << *I);
5263 if (!I->use_empty())
5264 I->replaceAllUsesWith(UndefValue::get(I->getType()));
5265 I->eraseFromParent();
5270 while (!WorkList.empty()) {
5271 Instruction *I = WorkList.back(); // Get an instruction from the worklist
5272 WorkList.pop_back();
5274 // Check to see if we can DCE or ConstantPropagate the instruction...
5275 // Check to see if we can DIE the instruction...
5276 if (isInstructionTriviallyDead(I)) {
5277 // Add operands to the worklist...
5278 if (I->getNumOperands() < 4)
5279 AddUsesToWorkList(*I);
5282 DEBUG(std::cerr << "IC: DCE: " << *I);
5284 I->eraseFromParent();
5285 removeFromWorkList(I);
5289 // Instruction isn't dead, see if we can constant propagate it...
5290 if (Constant *C = ConstantFoldInstruction(I)) {
5291 Value* Ptr = I->getOperand(0);
5292 if (isa<GetElementPtrInst>(I) &&
5293 cast<Constant>(Ptr)->isNullValue() &&
5294 !isa<ConstantPointerNull>(C) &&
5295 cast<PointerType>(Ptr->getType())->getElementType()->isSized()) {
5296 // If this is a constant expr gep that is effectively computing an
5297 // "offsetof", fold it into 'cast int X to T*' instead of 'gep 0, 0, 12'
5298 bool isFoldableGEP = true;
5299 for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
5300 if (!isa<ConstantInt>(I->getOperand(i)))
5301 isFoldableGEP = false;
5302 if (isFoldableGEP) {
5303 uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
5304 std::vector<Value*>(I->op_begin()+1, I->op_end()));
5305 C = ConstantUInt::get(Type::ULongTy, Offset);
5306 C = ConstantExpr::getCast(C, TD->getIntPtrType());
5307 C = ConstantExpr::getCast(C, I->getType());
5311 DEBUG(std::cerr << "IC: ConstFold to: " << *C << " from: " << *I);
5313 // Add operands to the worklist...
5314 AddUsesToWorkList(*I);
5315 ReplaceInstUsesWith(*I, C);
5318 I->getParent()->getInstList().erase(I);
5319 removeFromWorkList(I);
5323 // See if we can trivially sink this instruction to a successor basic block.
5324 if (I->hasOneUse()) {
5325 BasicBlock *BB = I->getParent();
5326 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
5327 if (UserParent != BB) {
5328 bool UserIsSuccessor = false;
5329 // See if the user is one of our successors.
5330 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
5331 if (*SI == UserParent) {
5332 UserIsSuccessor = true;
5336 // If the user is one of our immediate successors, and if that successor
5337 // only has us as a predecessors (we'd have to split the critical edge
5338 // otherwise), we can keep going.
5339 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
5340 next(pred_begin(UserParent)) == pred_end(UserParent))
5341 // Okay, the CFG is simple enough, try to sink this instruction.
5342 Changed |= TryToSinkInstruction(I, UserParent);
5346 // Now that we have an instruction, try combining it to simplify it...
5347 if (Instruction *Result = visit(*I)) {
5349 // Should we replace the old instruction with a new one?
5351 DEBUG(std::cerr << "IC: Old = " << *I
5352 << " New = " << *Result);
5354 // Everything uses the new instruction now.
5355 I->replaceAllUsesWith(Result);
5357 // Push the new instruction and any users onto the worklist.
5358 WorkList.push_back(Result);
5359 AddUsersToWorkList(*Result);
5361 // Move the name to the new instruction first...
5362 std::string OldName = I->getName(); I->setName("");
5363 Result->setName(OldName);
5365 // Insert the new instruction into the basic block...
5366 BasicBlock *InstParent = I->getParent();
5367 BasicBlock::iterator InsertPos = I;
5369 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
5370 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
5373 InstParent->getInstList().insert(InsertPos, Result);
5375 // Make sure that we reprocess all operands now that we reduced their
5377 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
5378 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
5379 WorkList.push_back(OpI);
5381 // Instructions can end up on the worklist more than once. Make sure
5382 // we do not process an instruction that has been deleted.
5383 removeFromWorkList(I);
5385 // Erase the old instruction.
5386 InstParent->getInstList().erase(I);
5388 DEBUG(std::cerr << "IC: MOD = " << *I);
5390 // If the instruction was modified, it's possible that it is now dead.
5391 // if so, remove it.
5392 if (isInstructionTriviallyDead(I)) {
5393 // Make sure we process all operands now that we are reducing their
5395 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
5396 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
5397 WorkList.push_back(OpI);
5399 // Instructions may end up in the worklist more than once. Erase all
5400 // occurrances of this instruction.
5401 removeFromWorkList(I);
5402 I->eraseFromParent();
5404 WorkList.push_back(Result);
5405 AddUsersToWorkList(*Result);
5415 FunctionPass *llvm::createInstructionCombiningPass() {
5416 return new InstCombiner();