1 //===- InstructionCombining.cpp - Combine multiple instructions -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // InstructionCombining - Combine instructions to form fewer, simple
11 // instructions. This pass does not modify the CFG This pass is where algebraic
12 // simplification happens.
14 // This pass combines things like:
20 // This is a simple worklist driven algorithm.
22 // This pass guarantees that the following canonicalizations are performed on
24 // 1. If a binary operator has a constant operand, it is moved to the RHS
25 // 2. Bitwise operators with constant operands are always grouped so that
26 // shifts are performed first, then or's, then and's, then xor's.
27 // 3. SetCC instructions are converted from <,>,<=,>= to ==,!= if possible
28 // 4. All SetCC instructions on boolean values are replaced with logical ops
29 // 5. add X, X is represented as (X*2) => (X << 1)
30 // 6. Multiplies with a power-of-two constant argument are transformed into
34 //===----------------------------------------------------------------------===//
36 #define DEBUG_TYPE "instcombine"
37 #include "llvm/Transforms/Scalar.h"
38 #include "llvm/IntrinsicInst.h"
39 #include "llvm/Pass.h"
40 #include "llvm/DerivedTypes.h"
41 #include "llvm/GlobalVariable.h"
42 #include "llvm/Target/TargetData.h"
43 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
44 #include "llvm/Transforms/Utils/Local.h"
45 #include "llvm/Support/CallSite.h"
46 #include "llvm/Support/Debug.h"
47 #include "llvm/Support/GetElementPtrTypeIterator.h"
48 #include "llvm/Support/InstVisitor.h"
49 #include "llvm/Support/MathExtras.h"
50 #include "llvm/Support/PatternMatch.h"
51 #include "llvm/ADT/DepthFirstIterator.h"
52 #include "llvm/ADT/Statistic.h"
53 #include "llvm/ADT/STLExtras.h"
56 using namespace llvm::PatternMatch;
59 Statistic<> NumCombined ("instcombine", "Number of insts combined");
60 Statistic<> NumConstProp("instcombine", "Number of constant folds");
61 Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
62 Statistic<> NumSunkInst ("instcombine", "Number of instructions sunk");
64 class InstCombiner : public FunctionPass,
65 public InstVisitor<InstCombiner, Instruction*> {
66 // Worklist of all of the instructions that need to be simplified.
67 std::vector<Instruction*> WorkList;
70 /// AddUsersToWorkList - When an instruction is simplified, add all users of
71 /// the instruction to the work lists because they might get more simplified
74 void AddUsersToWorkList(Instruction &I) {
75 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
77 WorkList.push_back(cast<Instruction>(*UI));
80 /// AddUsesToWorkList - When an instruction is simplified, add operands to
81 /// the work lists because they might get more simplified now.
83 void AddUsesToWorkList(Instruction &I) {
84 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
85 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
86 WorkList.push_back(Op);
89 // removeFromWorkList - remove all instances of I from the worklist.
90 void removeFromWorkList(Instruction *I);
92 virtual bool runOnFunction(Function &F);
94 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
95 AU.addRequired<TargetData>();
99 TargetData &getTargetData() const { return *TD; }
101 // Visitation implementation - Implement instruction combining for different
102 // instruction types. The semantics are as follows:
104 // null - No change was made
105 // I - Change was made, I is still valid, I may be dead though
106 // otherwise - Change was made, replace I with returned instruction
108 Instruction *visitAdd(BinaryOperator &I);
109 Instruction *visitSub(BinaryOperator &I);
110 Instruction *visitMul(BinaryOperator &I);
111 Instruction *visitDiv(BinaryOperator &I);
112 Instruction *visitRem(BinaryOperator &I);
113 Instruction *visitAnd(BinaryOperator &I);
114 Instruction *visitOr (BinaryOperator &I);
115 Instruction *visitXor(BinaryOperator &I);
116 Instruction *visitSetCondInst(SetCondInst &I);
117 Instruction *visitSetCondInstWithCastAndCast(SetCondInst &SCI);
119 Instruction *FoldGEPSetCC(User *GEPLHS, Value *RHS,
120 Instruction::BinaryOps Cond, Instruction &I);
121 Instruction *visitShiftInst(ShiftInst &I);
122 Instruction *visitCastInst(CastInst &CI);
123 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
125 Instruction *visitSelectInst(SelectInst &CI);
126 Instruction *visitCallInst(CallInst &CI);
127 Instruction *visitInvokeInst(InvokeInst &II);
128 Instruction *visitPHINode(PHINode &PN);
129 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
130 Instruction *visitAllocationInst(AllocationInst &AI);
131 Instruction *visitFreeInst(FreeInst &FI);
132 Instruction *visitLoadInst(LoadInst &LI);
133 Instruction *visitStoreInst(StoreInst &SI);
134 Instruction *visitBranchInst(BranchInst &BI);
135 Instruction *visitSwitchInst(SwitchInst &SI);
137 // visitInstruction - Specify what to return for unhandled instructions...
138 Instruction *visitInstruction(Instruction &I) { return 0; }
141 Instruction *visitCallSite(CallSite CS);
142 bool transformConstExprCastCall(CallSite CS);
145 // InsertNewInstBefore - insert an instruction New before instruction Old
146 // in the program. Add the new instruction to the worklist.
148 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
149 assert(New && New->getParent() == 0 &&
150 "New instruction already inserted into a basic block!");
151 BasicBlock *BB = Old.getParent();
152 BB->getInstList().insert(&Old, New); // Insert inst
153 WorkList.push_back(New); // Add to worklist
157 /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
158 /// This also adds the cast to the worklist. Finally, this returns the
160 Value *InsertCastBefore(Value *V, const Type *Ty, Instruction &Pos) {
161 if (V->getType() == Ty) return V;
163 Instruction *C = new CastInst(V, Ty, V->getName(), &Pos);
164 WorkList.push_back(C);
168 // ReplaceInstUsesWith - This method is to be used when an instruction is
169 // found to be dead, replacable with another preexisting expression. Here
170 // we add all uses of I to the worklist, replace all uses of I with the new
171 // value, then return I, so that the inst combiner will know that I was
174 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
175 AddUsersToWorkList(I); // Add all modified instrs to worklist
177 I.replaceAllUsesWith(V);
180 // If we are replacing the instruction with itself, this must be in a
181 // segment of unreachable code, so just clobber the instruction.
182 I.replaceAllUsesWith(UndefValue::get(I.getType()));
187 // EraseInstFromFunction - When dealing with an instruction that has side
188 // effects or produces a void value, we can't rely on DCE to delete the
189 // instruction. Instead, visit methods should return the value returned by
191 Instruction *EraseInstFromFunction(Instruction &I) {
192 assert(I.use_empty() && "Cannot erase instruction that is used!");
193 AddUsesToWorkList(I);
194 removeFromWorkList(&I);
196 return 0; // Don't do anything with FI
201 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
202 /// InsertBefore instruction. This is specialized a bit to avoid inserting
203 /// casts that are known to not do anything...
205 Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
206 Instruction *InsertBefore);
208 // SimplifyCommutative - This performs a few simplifications for commutative
210 bool SimplifyCommutative(BinaryOperator &I);
213 // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
214 // PHI node as operand #0, see if we can fold the instruction into the PHI
215 // (which is only possible if all operands to the PHI are constants).
216 Instruction *FoldOpIntoPhi(Instruction &I);
218 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
219 // operator and they all are only used by the PHI, PHI together their
220 // inputs, and do the operation once, to the result of the PHI.
221 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
223 Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
224 ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
226 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
227 bool Inside, Instruction &IB);
230 RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
233 // getComplexity: Assign a complexity or rank value to LLVM Values...
234 // 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
235 static unsigned getComplexity(Value *V) {
236 if (isa<Instruction>(V)) {
237 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
241 if (isa<Argument>(V)) return 3;
242 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
245 // isOnlyUse - Return true if this instruction will be deleted if we stop using
247 static bool isOnlyUse(Value *V) {
248 return V->hasOneUse() || isa<Constant>(V);
251 // getPromotedType - Return the specified type promoted as it would be to pass
252 // though a va_arg area...
253 static const Type *getPromotedType(const Type *Ty) {
254 switch (Ty->getTypeID()) {
255 case Type::SByteTyID:
256 case Type::ShortTyID: return Type::IntTy;
257 case Type::UByteTyID:
258 case Type::UShortTyID: return Type::UIntTy;
259 case Type::FloatTyID: return Type::DoubleTy;
264 // SimplifyCommutative - This performs a few simplifications for commutative
267 // 1. Order operands such that they are listed from right (least complex) to
268 // left (most complex). This puts constants before unary operators before
271 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
272 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
274 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
275 bool Changed = false;
276 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
277 Changed = !I.swapOperands();
279 if (!I.isAssociative()) return Changed;
280 Instruction::BinaryOps Opcode = I.getOpcode();
281 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
282 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
283 if (isa<Constant>(I.getOperand(1))) {
284 Constant *Folded = ConstantExpr::get(I.getOpcode(),
285 cast<Constant>(I.getOperand(1)),
286 cast<Constant>(Op->getOperand(1)));
287 I.setOperand(0, Op->getOperand(0));
288 I.setOperand(1, Folded);
290 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
291 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
292 isOnlyUse(Op) && isOnlyUse(Op1)) {
293 Constant *C1 = cast<Constant>(Op->getOperand(1));
294 Constant *C2 = cast<Constant>(Op1->getOperand(1));
296 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
297 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
298 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
301 WorkList.push_back(New);
302 I.setOperand(0, New);
303 I.setOperand(1, Folded);
310 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
311 // if the LHS is a constant zero (which is the 'negate' form).
313 static inline Value *dyn_castNegVal(Value *V) {
314 if (BinaryOperator::isNeg(V))
315 return BinaryOperator::getNegArgument(V);
317 // Constants can be considered to be negated values if they can be folded.
318 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
319 return ConstantExpr::getNeg(C);
323 static inline Value *dyn_castNotVal(Value *V) {
324 if (BinaryOperator::isNot(V))
325 return BinaryOperator::getNotArgument(V);
327 // Constants can be considered to be not'ed values...
328 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
329 return ConstantExpr::getNot(C);
333 // dyn_castFoldableMul - If this value is a multiply that can be folded into
334 // other computations (because it has a constant operand), return the
335 // non-constant operand of the multiply, and set CST to point to the multiplier.
336 // Otherwise, return null.
338 static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
339 if (V->hasOneUse() && V->getType()->isInteger())
340 if (Instruction *I = dyn_cast<Instruction>(V)) {
341 if (I->getOpcode() == Instruction::Mul)
342 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
343 return I->getOperand(0);
344 if (I->getOpcode() == Instruction::Shl)
345 if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
346 // The multiplier is really 1 << CST.
347 Constant *One = ConstantInt::get(V->getType(), 1);
348 CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
349 return I->getOperand(0);
355 /// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
356 /// expression, return it.
357 static User *dyn_castGetElementPtr(Value *V) {
358 if (isa<GetElementPtrInst>(V)) return cast<User>(V);
359 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
360 if (CE->getOpcode() == Instruction::GetElementPtr)
361 return cast<User>(V);
365 // AddOne, SubOne - Add or subtract a constant one from an integer constant...
366 static ConstantInt *AddOne(ConstantInt *C) {
367 return cast<ConstantInt>(ConstantExpr::getAdd(C,
368 ConstantInt::get(C->getType(), 1)));
370 static ConstantInt *SubOne(ConstantInt *C) {
371 return cast<ConstantInt>(ConstantExpr::getSub(C,
372 ConstantInt::get(C->getType(), 1)));
375 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
376 // true when both operands are equal...
378 static bool isTrueWhenEqual(Instruction &I) {
379 return I.getOpcode() == Instruction::SetEQ ||
380 I.getOpcode() == Instruction::SetGE ||
381 I.getOpcode() == Instruction::SetLE;
384 /// AssociativeOpt - Perform an optimization on an associative operator. This
385 /// function is designed to check a chain of associative operators for a
386 /// potential to apply a certain optimization. Since the optimization may be
387 /// applicable if the expression was reassociated, this checks the chain, then
388 /// reassociates the expression as necessary to expose the optimization
389 /// opportunity. This makes use of a special Functor, which must define
390 /// 'shouldApply' and 'apply' methods.
392 template<typename Functor>
393 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
394 unsigned Opcode = Root.getOpcode();
395 Value *LHS = Root.getOperand(0);
397 // Quick check, see if the immediate LHS matches...
398 if (F.shouldApply(LHS))
399 return F.apply(Root);
401 // Otherwise, if the LHS is not of the same opcode as the root, return.
402 Instruction *LHSI = dyn_cast<Instruction>(LHS);
403 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
404 // Should we apply this transform to the RHS?
405 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
407 // If not to the RHS, check to see if we should apply to the LHS...
408 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
409 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
413 // If the functor wants to apply the optimization to the RHS of LHSI,
414 // reassociate the expression from ((? op A) op B) to (? op (A op B))
416 BasicBlock *BB = Root.getParent();
418 // Now all of the instructions are in the current basic block, go ahead
419 // and perform the reassociation.
420 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
422 // First move the selected RHS to the LHS of the root...
423 Root.setOperand(0, LHSI->getOperand(1));
425 // Make what used to be the LHS of the root be the user of the root...
426 Value *ExtraOperand = TmpLHSI->getOperand(1);
427 if (&Root == TmpLHSI) {
428 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
431 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
432 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
433 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
434 BasicBlock::iterator ARI = &Root; ++ARI;
435 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
438 // Now propagate the ExtraOperand down the chain of instructions until we
440 while (TmpLHSI != LHSI) {
441 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
442 // Move the instruction to immediately before the chain we are
443 // constructing to avoid breaking dominance properties.
444 NextLHSI->getParent()->getInstList().remove(NextLHSI);
445 BB->getInstList().insert(ARI, NextLHSI);
448 Value *NextOp = NextLHSI->getOperand(1);
449 NextLHSI->setOperand(1, ExtraOperand);
451 ExtraOperand = NextOp;
454 // Now that the instructions are reassociated, have the functor perform
455 // the transformation...
456 return F.apply(Root);
459 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
465 // AddRHS - Implements: X + X --> X << 1
468 AddRHS(Value *rhs) : RHS(rhs) {}
469 bool shouldApply(Value *LHS) const { return LHS == RHS; }
470 Instruction *apply(BinaryOperator &Add) const {
471 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
472 ConstantInt::get(Type::UByteTy, 1));
476 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
478 struct AddMaskingAnd {
480 AddMaskingAnd(Constant *c) : C2(c) {}
481 bool shouldApply(Value *LHS) const {
483 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
484 ConstantExpr::getAnd(C1, C2)->isNullValue();
486 Instruction *apply(BinaryOperator &Add) const {
487 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
491 static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
493 if (isa<CastInst>(I)) {
494 if (Constant *SOC = dyn_cast<Constant>(SO))
495 return ConstantExpr::getCast(SOC, I.getType());
497 return IC->InsertNewInstBefore(new CastInst(SO, I.getType(),
498 SO->getName() + ".cast"), I);
501 // Figure out if the constant is the left or the right argument.
502 bool ConstIsRHS = isa<Constant>(I.getOperand(1));
503 Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
505 if (Constant *SOC = dyn_cast<Constant>(SO)) {
507 return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
508 return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
511 Value *Op0 = SO, *Op1 = ConstOperand;
515 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
516 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
517 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&I))
518 New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh");
520 assert(0 && "Unknown binary instruction type!");
523 return IC->InsertNewInstBefore(New, I);
526 // FoldOpIntoSelect - Given an instruction with a select as one operand and a
527 // constant as the other operand, try to fold the binary operator into the
528 // select arguments. This also works for Cast instructions, which obviously do
529 // not have a second operand.
530 static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
532 // Don't modify shared select instructions
533 if (!SI->hasOneUse()) return 0;
534 Value *TV = SI->getOperand(1);
535 Value *FV = SI->getOperand(2);
537 if (isa<Constant>(TV) || isa<Constant>(FV)) {
538 // Bool selects with constant operands can be folded to logical ops.
539 if (SI->getType() == Type::BoolTy) return 0;
541 Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
542 Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
544 return new SelectInst(SI->getCondition(), SelectTrueVal,
551 /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
552 /// node as operand #0, see if we can fold the instruction into the PHI (which
553 /// is only possible if all operands to the PHI are constants).
554 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
555 PHINode *PN = cast<PHINode>(I.getOperand(0));
556 unsigned NumPHIValues = PN->getNumIncomingValues();
557 if (!PN->hasOneUse() || NumPHIValues == 0 ||
558 !isa<Constant>(PN->getIncomingValue(0))) return 0;
560 // Check to see if all of the operands of the PHI are constants. If not, we
561 // cannot do the transformation.
562 for (unsigned i = 1; i != NumPHIValues; ++i)
563 if (!isa<Constant>(PN->getIncomingValue(i)))
566 // Okay, we can do the transformation: create the new PHI node.
567 PHINode *NewPN = new PHINode(I.getType(), I.getName());
569 NewPN->reserveOperandSpace(PN->getNumOperands()/2);
570 InsertNewInstBefore(NewPN, *PN);
572 // Next, add all of the operands to the PHI.
573 if (I.getNumOperands() == 2) {
574 Constant *C = cast<Constant>(I.getOperand(1));
575 for (unsigned i = 0; i != NumPHIValues; ++i) {
576 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
577 NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
578 PN->getIncomingBlock(i));
581 assert(isa<CastInst>(I) && "Unary op should be a cast!");
582 const Type *RetTy = I.getType();
583 for (unsigned i = 0; i != NumPHIValues; ++i) {
584 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
585 NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
586 PN->getIncomingBlock(i));
589 return ReplaceInstUsesWith(I, NewPN);
592 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
593 bool Changed = SimplifyCommutative(I);
594 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
596 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
597 // X + undef -> undef
598 if (isa<UndefValue>(RHS))
599 return ReplaceInstUsesWith(I, RHS);
602 if (!I.getType()->isFloatingPoint() && // -0 + +0 = +0, so it's not a noop
604 return ReplaceInstUsesWith(I, LHS);
606 // X + (signbit) --> X ^ signbit
607 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
608 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
609 uint64_t Val = CI->getRawValue() & (1ULL << NumBits)-1;
610 if (Val == (1ULL << (NumBits-1)))
611 return BinaryOperator::createXor(LHS, RHS);
614 if (isa<PHINode>(LHS))
615 if (Instruction *NV = FoldOpIntoPhi(I))
620 if (I.getType()->isInteger()) {
621 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
623 if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
624 if (RHSI->getOpcode() == Instruction::Sub)
625 if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
626 return ReplaceInstUsesWith(I, RHSI->getOperand(0));
628 if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
629 if (LHSI->getOpcode() == Instruction::Sub)
630 if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
631 return ReplaceInstUsesWith(I, LHSI->getOperand(0));
636 if (Value *V = dyn_castNegVal(LHS))
637 return BinaryOperator::createSub(RHS, V);
640 if (!isa<Constant>(RHS))
641 if (Value *V = dyn_castNegVal(RHS))
642 return BinaryOperator::createSub(LHS, V);
646 if (Value *X = dyn_castFoldableMul(LHS, C2)) {
647 if (X == RHS) // X*C + X --> X * (C+1)
648 return BinaryOperator::createMul(RHS, AddOne(C2));
650 // X*C1 + X*C2 --> X * (C1+C2)
652 if (X == dyn_castFoldableMul(RHS, C1))
653 return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2));
656 // X + X*C --> X * (C+1)
657 if (dyn_castFoldableMul(RHS, C2) == LHS)
658 return BinaryOperator::createMul(LHS, AddOne(C2));
661 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
662 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
663 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
665 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
667 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
668 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
669 return BinaryOperator::createSub(C, X);
672 // (X & FF00) + xx00 -> (X+xx00) & FF00
673 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
674 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
676 // See if all bits from the first bit set in the Add RHS up are included
677 // in the mask. First, get the rightmost bit.
678 uint64_t AddRHSV = CRHS->getRawValue();
680 // Form a mask of all bits from the lowest bit added through the top.
681 uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
682 AddRHSHighBits &= ~0ULL >> (64-C2->getType()->getPrimitiveSizeInBits());
684 // See if the and mask includes all of these bits.
685 uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue();
687 if (AddRHSHighBits == AddRHSHighBitsAnd) {
688 // Okay, the xform is safe. Insert the new add pronto.
689 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
691 return BinaryOperator::createAnd(NewAdd, C2);
696 // Try to fold constant add into select arguments.
697 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
698 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
702 return Changed ? &I : 0;
705 // isSignBit - Return true if the value represented by the constant only has the
706 // highest order bit set.
707 static bool isSignBit(ConstantInt *CI) {
708 unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
709 return (CI->getRawValue() & (~0ULL >> (64-NumBits))) == (1ULL << (NumBits-1));
712 /// RemoveNoopCast - Strip off nonconverting casts from the value.
714 static Value *RemoveNoopCast(Value *V) {
715 if (CastInst *CI = dyn_cast<CastInst>(V)) {
716 const Type *CTy = CI->getType();
717 const Type *OpTy = CI->getOperand(0)->getType();
718 if (CTy->isInteger() && OpTy->isInteger()) {
719 if (CTy->getPrimitiveSizeInBits() == OpTy->getPrimitiveSizeInBits())
720 return RemoveNoopCast(CI->getOperand(0));
721 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
722 return RemoveNoopCast(CI->getOperand(0));
727 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
728 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
730 if (Op0 == Op1) // sub X, X -> 0
731 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
733 // If this is a 'B = x-(-A)', change to B = x+A...
734 if (Value *V = dyn_castNegVal(Op1))
735 return BinaryOperator::createAdd(Op0, V);
737 if (isa<UndefValue>(Op0))
738 return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
739 if (isa<UndefValue>(Op1))
740 return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
742 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
743 // Replace (-1 - A) with (~A)...
744 if (C->isAllOnesValue())
745 return BinaryOperator::createNot(Op1);
747 // C - ~X == X + (1+C)
749 if (match(Op1, m_Not(m_Value(X))))
750 return BinaryOperator::createAdd(X,
751 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
752 // -((uint)X >> 31) -> ((int)X >> 31)
753 // -((int)X >> 31) -> ((uint)X >> 31)
754 if (C->isNullValue()) {
755 Value *NoopCastedRHS = RemoveNoopCast(Op1);
756 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
757 if (SI->getOpcode() == Instruction::Shr)
758 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
760 if (SI->getType()->isSigned())
761 NewTy = SI->getType()->getUnsignedVersion();
763 NewTy = SI->getType()->getSignedVersion();
764 // Check to see if we are shifting out everything but the sign bit.
765 if (CU->getValue() == SI->getType()->getPrimitiveSizeInBits()-1) {
766 // Ok, the transformation is safe. Insert a cast of the incoming
767 // value, then the new shift, then the new cast.
768 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
769 SI->getOperand(0)->getName());
770 Value *InV = InsertNewInstBefore(FirstCast, I);
771 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
773 if (NewShift->getType() == I.getType())
776 InV = InsertNewInstBefore(NewShift, I);
777 return new CastInst(NewShift, I.getType());
783 // Try to fold constant sub into select arguments.
784 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
785 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
788 if (isa<PHINode>(Op0))
789 if (Instruction *NV = FoldOpIntoPhi(I))
793 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
794 if (Op1I->getOpcode() == Instruction::Add &&
795 !Op0->getType()->isFloatingPoint()) {
796 if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
797 return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
798 else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
799 return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
800 else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
801 if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
802 // C1-(X+C2) --> (C1-C2)-X
803 return BinaryOperator::createSub(ConstantExpr::getSub(CI1, CI2),
804 Op1I->getOperand(0));
808 if (Op1I->hasOneUse()) {
809 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
810 // is not used by anyone else...
812 if (Op1I->getOpcode() == Instruction::Sub &&
813 !Op1I->getType()->isFloatingPoint()) {
814 // Swap the two operands of the subexpr...
815 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
816 Op1I->setOperand(0, IIOp1);
817 Op1I->setOperand(1, IIOp0);
819 // Create the new top level add instruction...
820 return BinaryOperator::createAdd(Op0, Op1);
823 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
825 if (Op1I->getOpcode() == Instruction::And &&
826 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
827 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
830 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
831 return BinaryOperator::createAnd(Op0, NewNot);
834 // -(X sdiv C) -> (X sdiv -C)
835 if (Op1I->getOpcode() == Instruction::Div)
836 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
837 if (CSI->isNullValue())
838 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
839 return BinaryOperator::createDiv(Op1I->getOperand(0),
840 ConstantExpr::getNeg(DivRHS));
842 // X - X*C --> X * (1-C)
844 if (dyn_castFoldableMul(Op1I, C2) == Op0) {
846 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
847 return BinaryOperator::createMul(Op0, CP1);
852 if (!Op0->getType()->isFloatingPoint())
853 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
854 if (Op0I->getOpcode() == Instruction::Add) {
855 if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
856 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
857 else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
858 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
859 } else if (Op0I->getOpcode() == Instruction::Sub) {
860 if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
861 return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName());
865 if (Value *X = dyn_castFoldableMul(Op0, C1)) {
866 if (X == Op1) { // X*C - X --> X * (C-1)
867 Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
868 return BinaryOperator::createMul(Op1, CP1);
871 ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
872 if (X == dyn_castFoldableMul(Op1, C2))
873 return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
878 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
879 /// really just returns true if the most significant (sign) bit is set.
880 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
881 if (RHS->getType()->isSigned()) {
882 // True if source is LHS < 0 or LHS <= -1
883 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
884 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
886 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
887 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
888 // the size of the integer type.
889 if (Opcode == Instruction::SetGE)
890 return RHSC->getValue() ==
891 1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1);
892 if (Opcode == Instruction::SetGT)
893 return RHSC->getValue() ==
894 (1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1))-1;
899 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
900 bool Changed = SimplifyCommutative(I);
901 Value *Op0 = I.getOperand(0);
903 if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
904 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
906 // Simplify mul instructions with a constant RHS...
907 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
908 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
910 // ((X << C1)*C2) == (X * (C2 << C1))
911 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
912 if (SI->getOpcode() == Instruction::Shl)
913 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
914 return BinaryOperator::createMul(SI->getOperand(0),
915 ConstantExpr::getShl(CI, ShOp));
917 if (CI->isNullValue())
918 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
919 if (CI->equalsInt(1)) // X * 1 == X
920 return ReplaceInstUsesWith(I, Op0);
921 if (CI->isAllOnesValue()) // X * -1 == 0 - X
922 return BinaryOperator::createNeg(Op0, I.getName());
924 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
925 if (isPowerOf2_64(Val)) { // Replace X*(2^C) with X << C
926 uint64_t C = Log2_64(Val);
927 return new ShiftInst(Instruction::Shl, Op0,
928 ConstantUInt::get(Type::UByteTy, C));
930 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
931 if (Op1F->isNullValue())
932 return ReplaceInstUsesWith(I, Op1);
934 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
935 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
936 if (Op1F->getValue() == 1.0)
937 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
940 // Try to fold constant mul into select arguments.
941 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
942 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
945 if (isa<PHINode>(Op0))
946 if (Instruction *NV = FoldOpIntoPhi(I))
950 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
951 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
952 return BinaryOperator::createMul(Op0v, Op1v);
954 // If one of the operands of the multiply is a cast from a boolean value, then
955 // we know the bool is either zero or one, so this is a 'masking' multiply.
956 // See if we can simplify things based on how the boolean was originally
958 CastInst *BoolCast = 0;
959 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
960 if (CI->getOperand(0)->getType() == Type::BoolTy)
963 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
964 if (CI->getOperand(0)->getType() == Type::BoolTy)
967 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
968 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
969 const Type *SCOpTy = SCIOp0->getType();
971 // If the setcc is true iff the sign bit of X is set, then convert this
972 // multiply into a shift/and combination.
973 if (isa<ConstantInt>(SCIOp1) &&
974 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
975 // Shift the X value right to turn it into "all signbits".
976 Constant *Amt = ConstantUInt::get(Type::UByteTy,
977 SCOpTy->getPrimitiveSizeInBits()-1);
978 if (SCIOp0->getType()->isUnsigned()) {
979 const Type *NewTy = SCIOp0->getType()->getSignedVersion();
980 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
981 SCIOp0->getName()), I);
985 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
986 BoolCast->getOperand(0)->getName()+
989 // If the multiply type is not the same as the source type, sign extend
990 // or truncate to the multiply type.
991 if (I.getType() != V->getType())
992 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
994 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
995 return BinaryOperator::createAnd(V, OtherOp);
1000 return Changed ? &I : 0;
1003 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
1004 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1006 if (isa<UndefValue>(Op0)) // undef / X -> 0
1007 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1008 if (isa<UndefValue>(Op1))
1009 return ReplaceInstUsesWith(I, Op1); // X / undef -> undef
1011 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1013 if (RHS->equalsInt(1))
1014 return ReplaceInstUsesWith(I, Op0);
1017 if (RHS->isAllOnesValue())
1018 return BinaryOperator::createNeg(Op0);
1020 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
1021 if (LHS->getOpcode() == Instruction::Div)
1022 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
1023 // (X / C1) / C2 -> X / (C1*C2)
1024 return BinaryOperator::createDiv(LHS->getOperand(0),
1025 ConstantExpr::getMul(RHS, LHSRHS));
1028 // Check to see if this is an unsigned division with an exact power of 2,
1029 // if so, convert to a right shift.
1030 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1031 if (uint64_t Val = C->getValue()) // Don't break X / 0
1032 if (isPowerOf2_64(Val)) {
1033 uint64_t C = Log2_64(Val);
1034 return new ShiftInst(Instruction::Shr, Op0,
1035 ConstantUInt::get(Type::UByteTy, C));
1039 if (RHS->getType()->isSigned())
1040 if (Value *LHSNeg = dyn_castNegVal(Op0))
1041 return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS));
1043 if (!RHS->isNullValue()) {
1044 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1045 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1047 if (isa<PHINode>(Op0))
1048 if (Instruction *NV = FoldOpIntoPhi(I))
1053 // If this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1054 // transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'.
1055 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1056 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1057 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1058 if (STO->getValue() == 0) { // Couldn't be this argument.
1059 I.setOperand(1, SFO);
1061 } else if (SFO->getValue() == 0) {
1062 I.setOperand(1, STO);
1066 uint64_t TVA = STO->getValue(), FVA = SFO->getValue();
1067 if (isPowerOf2_64(TVA) && isPowerOf2_64(FVA)) {
1068 unsigned TSA = Log2_64(TVA), FSA = Log2_64(FVA);
1069 Constant *TC = ConstantUInt::get(Type::UByteTy, TSA);
1070 Instruction *TSI = new ShiftInst(Instruction::Shr, Op0,
1071 TC, SI->getName()+".t");
1072 TSI = InsertNewInstBefore(TSI, I);
1074 Constant *FC = ConstantUInt::get(Type::UByteTy, FSA);
1075 Instruction *FSI = new ShiftInst(Instruction::Shr, Op0,
1076 FC, SI->getName()+".f");
1077 FSI = InsertNewInstBefore(FSI, I);
1078 return new SelectInst(SI->getOperand(0), TSI, FSI);
1082 // 0 / X == 0, we don't need to preserve faults!
1083 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1084 if (LHS->equalsInt(0))
1085 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1091 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
1092 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1093 if (I.getType()->isSigned())
1094 if (Value *RHSNeg = dyn_castNegVal(Op1))
1095 if (!isa<ConstantSInt>(RHSNeg) ||
1096 cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
1098 AddUsesToWorkList(I);
1099 I.setOperand(1, RHSNeg);
1103 if (isa<UndefValue>(Op0)) // undef % X -> 0
1104 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1105 if (isa<UndefValue>(Op1))
1106 return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
1108 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1109 if (RHS->equalsInt(1)) // X % 1 == 0
1110 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1112 // Check to see if this is an unsigned remainder with an exact power of 2,
1113 // if so, convert to a bitwise and.
1114 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
1115 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
1116 if (!(Val & (Val-1))) // Power of 2
1117 return BinaryOperator::createAnd(Op0,
1118 ConstantUInt::get(I.getType(), Val-1));
1120 if (!RHS->isNullValue()) {
1121 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1122 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1124 if (isa<PHINode>(Op0))
1125 if (Instruction *NV = FoldOpIntoPhi(I))
1130 // If this is 'urem X, (Cond ? C1, C2)' where C1&C2 are powers of two,
1131 // transform this into: '(Cond ? (urem X, C1) : (urem X, C2))'.
1132 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1133 if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
1134 if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
1135 if (STO->getValue() == 0) { // Couldn't be this argument.
1136 I.setOperand(1, SFO);
1138 } else if (SFO->getValue() == 0) {
1139 I.setOperand(1, STO);
1143 if (!(STO->getValue() & (STO->getValue()-1)) &&
1144 !(SFO->getValue() & (SFO->getValue()-1))) {
1145 Value *TrueAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1146 SubOne(STO), SI->getName()+".t"), I);
1147 Value *FalseAnd = InsertNewInstBefore(BinaryOperator::createAnd(Op0,
1148 SubOne(SFO), SI->getName()+".f"), I);
1149 return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
1153 // 0 % X == 0, we don't need to preserve faults!
1154 if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
1155 if (LHS->equalsInt(0))
1156 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1161 // isMaxValueMinusOne - return true if this is Max-1
1162 static bool isMaxValueMinusOne(const ConstantInt *C) {
1163 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
1164 // Calculate -1 casted to the right type...
1165 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1166 uint64_t Val = ~0ULL; // All ones
1167 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1168 return CU->getValue() == Val-1;
1171 const ConstantSInt *CS = cast<ConstantSInt>(C);
1173 // Calculate 0111111111..11111
1174 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1175 int64_t Val = INT64_MAX; // All ones
1176 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1177 return CS->getValue() == Val-1;
1180 // isMinValuePlusOne - return true if this is Min+1
1181 static bool isMinValuePlusOne(const ConstantInt *C) {
1182 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1183 return CU->getValue() == 1;
1185 const ConstantSInt *CS = cast<ConstantSInt>(C);
1187 // Calculate 1111111111000000000000
1188 unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
1189 int64_t Val = -1; // All ones
1190 Val <<= TypeBits-1; // Shift over to the right spot
1191 return CS->getValue() == Val+1;
1194 // isOneBitSet - Return true if there is exactly one bit set in the specified
1196 static bool isOneBitSet(const ConstantInt *CI) {
1197 uint64_t V = CI->getRawValue();
1198 return V && (V & (V-1)) == 0;
1201 #if 0 // Currently unused
1202 // isLowOnes - Return true if the constant is of the form 0+1+.
1203 static bool isLowOnes(const ConstantInt *CI) {
1204 uint64_t V = CI->getRawValue();
1206 // There won't be bits set in parts that the type doesn't contain.
1207 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1209 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1210 return U && V && (U & V) == 0;
1214 // isHighOnes - Return true if the constant is of the form 1+0+.
1215 // This is the same as lowones(~X).
1216 static bool isHighOnes(const ConstantInt *CI) {
1217 uint64_t V = ~CI->getRawValue();
1218 if (~V == 0) return false; // 0's does not match "1+"
1220 // There won't be bits set in parts that the type doesn't contain.
1221 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1223 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1224 return U && V && (U & V) == 0;
1228 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
1229 /// are carefully arranged to allow folding of expressions such as:
1231 /// (A < B) | (A > B) --> (A != B)
1233 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
1234 /// represents that the comparison is true if A == B, and bit value '1' is true
1237 static unsigned getSetCondCode(const SetCondInst *SCI) {
1238 switch (SCI->getOpcode()) {
1240 case Instruction::SetGT: return 1;
1241 case Instruction::SetEQ: return 2;
1242 case Instruction::SetGE: return 3;
1243 case Instruction::SetLT: return 4;
1244 case Instruction::SetNE: return 5;
1245 case Instruction::SetLE: return 6;
1248 assert(0 && "Invalid SetCC opcode!");
1253 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
1254 /// opcode and two operands into either a constant true or false, or a brand new
1255 /// SetCC instruction.
1256 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
1258 case 0: return ConstantBool::False;
1259 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
1260 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
1261 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
1262 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
1263 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
1264 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
1265 case 7: return ConstantBool::True;
1266 default: assert(0 && "Illegal SetCCCode!"); return 0;
1270 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1271 struct FoldSetCCLogical {
1274 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
1275 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
1276 bool shouldApply(Value *V) const {
1277 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
1278 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
1279 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
1282 Instruction *apply(BinaryOperator &Log) const {
1283 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
1284 if (SCI->getOperand(0) != LHS) {
1285 assert(SCI->getOperand(1) == LHS);
1286 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
1289 unsigned LHSCode = getSetCondCode(SCI);
1290 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
1292 switch (Log.getOpcode()) {
1293 case Instruction::And: Code = LHSCode & RHSCode; break;
1294 case Instruction::Or: Code = LHSCode | RHSCode; break;
1295 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
1296 default: assert(0 && "Illegal logical opcode!"); return 0;
1299 Value *RV = getSetCCValue(Code, LHS, RHS);
1300 if (Instruction *I = dyn_cast<Instruction>(RV))
1302 // Otherwise, it's a constant boolean value...
1303 return IC.ReplaceInstUsesWith(Log, RV);
1308 /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
1309 /// this predicate to simplify operations downstream. V and Mask are known to
1310 /// be the same type.
1311 static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask) {
1312 // Note, we cannot consider 'undef' to be "IsZero" here. The problem is that
1313 // we cannot optimize based on the assumption that it is zero without changing
1314 // to to an explicit zero. If we don't change it to zero, other code could
1315 // optimized based on the contradictory assumption that it is non-zero.
1316 // Because instcombine aggressively folds operations with undef args anyway,
1317 // this won't lose us code quality.
1318 if (Mask->isNullValue())
1320 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
1321 return ConstantExpr::getAnd(CI, Mask)->isNullValue();
1323 if (Instruction *I = dyn_cast<Instruction>(V)) {
1324 switch (I->getOpcode()) {
1325 case Instruction::And:
1326 // (X & C1) & C2 == 0 iff C1 & C2 == 0.
1327 if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1)))
1328 if (ConstantExpr::getAnd(CI, Mask)->isNullValue())
1331 case Instruction::Or:
1332 // If the LHS and the RHS are MaskedValueIsZero, the result is also zero.
1333 return MaskedValueIsZero(I->getOperand(1), Mask) &&
1334 MaskedValueIsZero(I->getOperand(0), Mask);
1335 case Instruction::Select:
1336 // If the T and F values are MaskedValueIsZero, the result is also zero.
1337 return MaskedValueIsZero(I->getOperand(2), Mask) &&
1338 MaskedValueIsZero(I->getOperand(1), Mask);
1339 case Instruction::Cast: {
1340 const Type *SrcTy = I->getOperand(0)->getType();
1341 if (SrcTy == Type::BoolTy)
1342 return (Mask->getRawValue() & 1) == 0;
1344 if (SrcTy->isInteger()) {
1345 // (cast <ty> X to int) & C2 == 0 iff <ty> could not have contained C2.
1346 if (SrcTy->isUnsigned() && // Only handle zero ext.
1347 ConstantExpr::getCast(Mask, SrcTy)->isNullValue())
1350 // If this is a noop cast, recurse.
1351 if ((SrcTy->isSigned() && SrcTy->getUnsignedVersion() == I->getType())||
1352 SrcTy->getSignedVersion() == I->getType()) {
1354 ConstantExpr::getCast(Mask, I->getOperand(0)->getType());
1355 return MaskedValueIsZero(I->getOperand(0),
1356 cast<ConstantIntegral>(NewMask));
1361 case Instruction::Shl:
1362 // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
1363 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
1364 return MaskedValueIsZero(I->getOperand(0),
1365 cast<ConstantIntegral>(ConstantExpr::getUShr(Mask, SA)));
1367 case Instruction::Shr:
1368 // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
1369 if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
1370 if (I->getType()->isUnsigned()) {
1371 Constant *C1 = ConstantIntegral::getAllOnesValue(I->getType());
1372 C1 = ConstantExpr::getShr(C1, SA);
1373 C1 = ConstantExpr::getAnd(C1, Mask);
1374 if (C1->isNullValue())
1384 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
1385 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
1386 // guaranteed to be either a shift instruction or a binary operator.
1387 Instruction *InstCombiner::OptAndOp(Instruction *Op,
1388 ConstantIntegral *OpRHS,
1389 ConstantIntegral *AndRHS,
1390 BinaryOperator &TheAnd) {
1391 Value *X = Op->getOperand(0);
1392 Constant *Together = 0;
1393 if (!isa<ShiftInst>(Op))
1394 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
1396 switch (Op->getOpcode()) {
1397 case Instruction::Xor:
1398 if (Op->hasOneUse()) {
1399 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
1400 std::string OpName = Op->getName(); Op->setName("");
1401 Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
1402 InsertNewInstBefore(And, TheAnd);
1403 return BinaryOperator::createXor(And, Together);
1406 case Instruction::Or:
1407 if (Together == AndRHS) // (X | C) & C --> C
1408 return ReplaceInstUsesWith(TheAnd, AndRHS);
1410 if (Op->hasOneUse() && Together != OpRHS) {
1411 // (X | C1) & C2 --> (X | (C1&C2)) & C2
1412 std::string Op0Name = Op->getName(); Op->setName("");
1413 Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
1414 InsertNewInstBefore(Or, TheAnd);
1415 return BinaryOperator::createAnd(Or, AndRHS);
1418 case Instruction::Add:
1419 if (Op->hasOneUse()) {
1420 // Adding a one to a single bit bit-field should be turned into an XOR
1421 // of the bit. First thing to check is to see if this AND is with a
1422 // single bit constant.
1423 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
1425 // Clear bits that are not part of the constant.
1426 AndRHSV &= ~0ULL >> (64-AndRHS->getType()->getPrimitiveSizeInBits());
1428 // If there is only one bit set...
1429 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
1430 // Ok, at this point, we know that we are masking the result of the
1431 // ADD down to exactly one bit. If the constant we are adding has
1432 // no bits set below this bit, then we can eliminate the ADD.
1433 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
1435 // Check to see if any bits below the one bit set in AndRHSV are set.
1436 if ((AddRHS & (AndRHSV-1)) == 0) {
1437 // If not, the only thing that can effect the output of the AND is
1438 // the bit specified by AndRHSV. If that bit is set, the effect of
1439 // the XOR is to toggle the bit. If it is clear, then the ADD has
1441 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
1442 TheAnd.setOperand(0, X);
1445 std::string Name = Op->getName(); Op->setName("");
1446 // Pull the XOR out of the AND.
1447 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
1448 InsertNewInstBefore(NewAnd, TheAnd);
1449 return BinaryOperator::createXor(NewAnd, AndRHS);
1456 case Instruction::Shl: {
1457 // We know that the AND will not produce any of the bits shifted in, so if
1458 // the anded constant includes them, clear them now!
1460 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1461 Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
1462 Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
1464 if (CI == ShlMask) { // Masking out bits that the shift already masks
1465 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
1466 } else if (CI != AndRHS) { // Reducing bits set in and.
1467 TheAnd.setOperand(1, CI);
1472 case Instruction::Shr:
1473 // We know that the AND will not produce any of the bits shifted in, so if
1474 // the anded constant includes them, clear them now! This only applies to
1475 // unsigned shifts, because a signed shr may bring in set bits!
1477 if (AndRHS->getType()->isUnsigned()) {
1478 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1479 Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS);
1480 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1482 if (CI == ShrMask) { // Masking out bits that the shift already masks.
1483 return ReplaceInstUsesWith(TheAnd, Op);
1484 } else if (CI != AndRHS) {
1485 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
1488 } else { // Signed shr.
1489 // See if this is shifting in some sign extension, then masking it out
1491 if (Op->hasOneUse()) {
1492 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1493 Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS);
1494 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1495 if (CI == AndRHS) { // Masking out bits shifted in.
1496 // Make the argument unsigned.
1497 Value *ShVal = Op->getOperand(0);
1498 ShVal = InsertCastBefore(ShVal,
1499 ShVal->getType()->getUnsignedVersion(),
1501 ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal,
1502 OpRHS, Op->getName()),
1504 Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType());
1505 ShVal = InsertNewInstBefore(BinaryOperator::createAnd(ShVal, AndRHS2,
1508 return new CastInst(ShVal, Op->getType());
1518 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
1519 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
1520 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. IB is the location to
1521 /// insert new instructions.
1522 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
1523 bool Inside, Instruction &IB) {
1524 assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
1525 "Lo is not <= Hi in range emission code!");
1527 if (Lo == Hi) // Trivially false.
1528 return new SetCondInst(Instruction::SetNE, V, V);
1529 if (cast<ConstantIntegral>(Lo)->isMinValue())
1530 return new SetCondInst(Instruction::SetLT, V, Hi);
1532 Constant *AddCST = ConstantExpr::getNeg(Lo);
1533 Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
1534 InsertNewInstBefore(Add, IB);
1535 // Convert to unsigned for the comparison.
1536 const Type *UnsType = Add->getType()->getUnsignedVersion();
1537 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1538 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1539 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1540 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1543 if (Lo == Hi) // Trivially true.
1544 return new SetCondInst(Instruction::SetEQ, V, V);
1546 Hi = SubOne(cast<ConstantInt>(Hi));
1547 if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
1548 return new SetCondInst(Instruction::SetGT, V, Hi);
1550 // Emit X-Lo > Hi-Lo-1
1551 Constant *AddCST = ConstantExpr::getNeg(Lo);
1552 Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
1553 InsertNewInstBefore(Add, IB);
1554 // Convert to unsigned for the comparison.
1555 const Type *UnsType = Add->getType()->getUnsignedVersion();
1556 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1557 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1558 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1559 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1563 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1564 bool Changed = SimplifyCommutative(I);
1565 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1567 if (isa<UndefValue>(Op1)) // X & undef -> 0
1568 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1572 return ReplaceInstUsesWith(I, Op1);
1574 if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) {
1576 if (AndRHS->isAllOnesValue())
1577 return ReplaceInstUsesWith(I, Op0);
1579 if (MaskedValueIsZero(Op0, AndRHS)) // LHS & RHS == 0
1580 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1582 // If the mask is not masking out any bits, there is no reason to do the
1583 // and in the first place.
1584 ConstantIntegral *NotAndRHS =
1585 cast<ConstantIntegral>(ConstantExpr::getNot(AndRHS));
1586 if (MaskedValueIsZero(Op0, NotAndRHS))
1587 return ReplaceInstUsesWith(I, Op0);
1589 // Optimize a variety of ((val OP C1) & C2) combinations...
1590 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
1591 Instruction *Op0I = cast<Instruction>(Op0);
1592 Value *Op0LHS = Op0I->getOperand(0);
1593 Value *Op0RHS = Op0I->getOperand(1);
1594 switch (Op0I->getOpcode()) {
1595 case Instruction::Xor:
1596 case Instruction::Or:
1597 // (X ^ V) & C2 --> (X & C2) iff (V & C2) == 0
1598 // (X | V) & C2 --> (X & C2) iff (V & C2) == 0
1599 if (MaskedValueIsZero(Op0LHS, AndRHS))
1600 return BinaryOperator::createAnd(Op0RHS, AndRHS);
1601 if (MaskedValueIsZero(Op0RHS, AndRHS))
1602 return BinaryOperator::createAnd(Op0LHS, AndRHS);
1604 // If the mask is only needed on one incoming arm, push it up.
1605 if (Op0I->hasOneUse()) {
1606 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
1607 // Not masking anything out for the LHS, move to RHS.
1608 Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
1609 Op0RHS->getName()+".masked");
1610 InsertNewInstBefore(NewRHS, I);
1611 return BinaryOperator::create(
1612 cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
1614 if (!isa<Constant>(NotAndRHS) &&
1615 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
1616 // Not masking anything out for the RHS, move to LHS.
1617 Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
1618 Op0LHS->getName()+".masked");
1619 InsertNewInstBefore(NewLHS, I);
1620 return BinaryOperator::create(
1621 cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
1626 case Instruction::And:
1627 // (X & V) & C2 --> 0 iff (V & C2) == 0
1628 if (MaskedValueIsZero(Op0LHS, AndRHS) ||
1629 MaskedValueIsZero(Op0RHS, AndRHS))
1630 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1634 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1635 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
1637 } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
1638 const Type *SrcTy = CI->getOperand(0)->getType();
1640 // If this is an integer truncation or change from signed-to-unsigned, and
1641 // if the source is an and/or with immediate, transform it. This
1642 // frequently occurs for bitfield accesses.
1643 if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
1644 if (SrcTy->getPrimitiveSizeInBits() >=
1645 I.getType()->getPrimitiveSizeInBits() &&
1646 CastOp->getNumOperands() == 2)
1647 if (ConstantInt *AndCI =dyn_cast<ConstantInt>(CastOp->getOperand(1)))
1648 if (CastOp->getOpcode() == Instruction::And) {
1649 // Change: and (cast (and X, C1) to T), C2
1650 // into : and (cast X to T), trunc(C1)&C2
1651 // This will folds the two ands together, which may allow other
1653 Instruction *NewCast =
1654 new CastInst(CastOp->getOperand(0), I.getType(),
1655 CastOp->getName()+".shrunk");
1656 NewCast = InsertNewInstBefore(NewCast, I);
1658 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1659 C3 = ConstantExpr::getAnd(C3, AndRHS); // trunc(C1)&C2
1660 return BinaryOperator::createAnd(NewCast, C3);
1661 } else if (CastOp->getOpcode() == Instruction::Or) {
1662 // Change: and (cast (or X, C1) to T), C2
1663 // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
1664 Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
1665 if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
1666 return ReplaceInstUsesWith(I, AndRHS);
1671 // If this is an integer sign or zero extension instruction.
1672 if (SrcTy->isIntegral() &&
1673 SrcTy->getPrimitiveSizeInBits() <
1674 CI->getType()->getPrimitiveSizeInBits()) {
1676 if (SrcTy->isUnsigned()) {
1677 // See if this and is clearing out bits that are known to be zero
1678 // anyway (due to the zero extension).
1679 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1680 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1681 Constant *Result = ConstantExpr::getAnd(Mask, AndRHS);
1682 if (Result == Mask) // The "and" isn't doing anything, remove it.
1683 return ReplaceInstUsesWith(I, CI);
1684 if (Result != AndRHS) { // Reduce the and RHS constant.
1685 I.setOperand(1, Result);
1690 if (CI->hasOneUse() && SrcTy->isInteger()) {
1691 // We can only do this if all of the sign bits brought in are masked
1692 // out. Compute this by first getting 0000011111, then inverting
1694 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
1695 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
1696 Mask = ConstantExpr::getNot(Mask); // 1's in the new bits.
1697 if (ConstantExpr::getAnd(Mask, AndRHS)->isNullValue()) {
1698 // If the and is clearing all of the sign bits, change this to a
1699 // zero extension cast. To do this, cast the cast input to
1700 // unsigned, then to the requested size.
1701 Value *CastOp = CI->getOperand(0);
1703 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
1704 CI->getName()+".uns");
1705 NC = InsertNewInstBefore(NC, I);
1706 // Finally, insert a replacement for CI.
1707 NC = new CastInst(NC, CI->getType(), CI->getName());
1709 NC = InsertNewInstBefore(NC, I);
1710 WorkList.push_back(CI); // Delete CI later.
1711 I.setOperand(0, NC);
1712 return &I; // The AND operand was modified.
1719 // Try to fold constant and into select arguments.
1720 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1721 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1723 if (isa<PHINode>(Op0))
1724 if (Instruction *NV = FoldOpIntoPhi(I))
1728 Value *Op0NotVal = dyn_castNotVal(Op0);
1729 Value *Op1NotVal = dyn_castNotVal(Op1);
1731 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1732 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1734 // (~A & ~B) == (~(A | B)) - De Morgan's Law
1735 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1736 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
1737 I.getName()+".demorgan");
1738 InsertNewInstBefore(Or, I);
1739 return BinaryOperator::createNot(Or);
1742 if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
1743 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1744 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1747 Value *LHSVal, *RHSVal;
1748 ConstantInt *LHSCst, *RHSCst;
1749 Instruction::BinaryOps LHSCC, RHSCC;
1750 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1751 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1752 if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
1753 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1754 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1755 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1756 // Ensure that the larger constant is on the RHS.
1757 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1758 SetCondInst *LHS = cast<SetCondInst>(Op0);
1759 if (cast<ConstantBool>(Cmp)->getValue()) {
1760 std::swap(LHS, RHS);
1761 std::swap(LHSCst, RHSCst);
1762 std::swap(LHSCC, RHSCC);
1765 // At this point, we know we have have two setcc instructions
1766 // comparing a value against two constants and and'ing the result
1767 // together. Because of the above check, we know that we only have
1768 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1769 // FoldSetCCLogical check above), that the two constants are not
1771 assert(LHSCst != RHSCst && "Compares not folded above?");
1774 default: assert(0 && "Unknown integer condition code!");
1775 case Instruction::SetEQ:
1777 default: assert(0 && "Unknown integer condition code!");
1778 case Instruction::SetEQ: // (X == 13 & X == 15) -> false
1779 case Instruction::SetGT: // (X == 13 & X > 15) -> false
1780 return ReplaceInstUsesWith(I, ConstantBool::False);
1781 case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
1782 case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
1783 return ReplaceInstUsesWith(I, LHS);
1785 case Instruction::SetNE:
1787 default: assert(0 && "Unknown integer condition code!");
1788 case Instruction::SetLT:
1789 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
1790 return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
1791 break; // (X != 13 & X < 15) -> no change
1792 case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
1793 case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
1794 return ReplaceInstUsesWith(I, RHS);
1795 case Instruction::SetNE:
1796 if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
1797 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1798 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
1799 LHSVal->getName()+".off");
1800 InsertNewInstBefore(Add, I);
1801 const Type *UnsType = Add->getType()->getUnsignedVersion();
1802 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
1803 AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
1804 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1805 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1807 break; // (X != 13 & X != 15) -> no change
1810 case Instruction::SetLT:
1812 default: assert(0 && "Unknown integer condition code!");
1813 case Instruction::SetEQ: // (X < 13 & X == 15) -> false
1814 case Instruction::SetGT: // (X < 13 & X > 15) -> false
1815 return ReplaceInstUsesWith(I, ConstantBool::False);
1816 case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
1817 case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
1818 return ReplaceInstUsesWith(I, LHS);
1820 case Instruction::SetGT:
1822 default: assert(0 && "Unknown integer condition code!");
1823 case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
1824 return ReplaceInstUsesWith(I, LHS);
1825 case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
1826 return ReplaceInstUsesWith(I, RHS);
1827 case Instruction::SetNE:
1828 if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
1829 return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
1830 break; // (X > 13 & X != 15) -> no change
1831 case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
1832 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
1838 return Changed ? &I : 0;
1841 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
1842 bool Changed = SimplifyCommutative(I);
1843 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1845 if (isa<UndefValue>(Op1))
1846 return ReplaceInstUsesWith(I, // X | undef -> -1
1847 ConstantIntegral::getAllOnesValue(I.getType()));
1849 // or X, X = X or X, 0 == X
1850 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
1851 return ReplaceInstUsesWith(I, Op0);
1854 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1855 // If X is known to only contain bits that already exist in RHS, just
1856 // replace this instruction with RHS directly.
1857 if (MaskedValueIsZero(Op0,
1858 cast<ConstantIntegral>(ConstantExpr::getNot(RHS))))
1859 return ReplaceInstUsesWith(I, RHS);
1861 ConstantInt *C1; Value *X;
1862 // (X & C1) | C2 --> (X | C2) & (C1|C2)
1863 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1864 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0->getName());
1866 InsertNewInstBefore(Or, I);
1867 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
1870 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
1871 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1872 std::string Op0Name = Op0->getName(); Op0->setName("");
1873 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
1874 InsertNewInstBefore(Or, I);
1875 return BinaryOperator::createXor(Or,
1876 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
1879 // Try to fold constant and into select arguments.
1880 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1881 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
1883 if (isa<PHINode>(Op0))
1884 if (Instruction *NV = FoldOpIntoPhi(I))
1888 Value *A, *B; ConstantInt *C1, *C2;
1890 if (match(Op0, m_And(m_Value(A), m_Value(B))))
1891 if (A == Op1 || B == Op1) // (A & ?) | A --> A
1892 return ReplaceInstUsesWith(I, Op1);
1893 if (match(Op1, m_And(m_Value(A), m_Value(B))))
1894 if (A == Op0 || B == Op0) // A | (A & ?) --> A
1895 return ReplaceInstUsesWith(I, Op0);
1897 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
1898 if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
1899 MaskedValueIsZero(Op1, C1)) {
1900 Instruction *NOr = BinaryOperator::createOr(A, Op1, Op0->getName());
1902 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
1905 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
1906 if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
1907 MaskedValueIsZero(Op0, C1)) {
1908 Instruction *NOr = BinaryOperator::createOr(A, Op0, Op1->getName());
1910 return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
1913 // (A & C1)|(A & C2) == A & (C1|C2)
1914 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
1915 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) && A == B)
1916 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
1918 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
1919 if (A == Op1) // ~A | A == -1
1920 return ReplaceInstUsesWith(I,
1921 ConstantIntegral::getAllOnesValue(I.getType()));
1925 // Note, A is still live here!
1926 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
1928 return ReplaceInstUsesWith(I,
1929 ConstantIntegral::getAllOnesValue(I.getType()));
1931 // (~A | ~B) == (~(A & B)) - De Morgan's Law
1932 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1933 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
1934 I.getName()+".demorgan"), I);
1935 return BinaryOperator::createNot(And);
1939 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
1940 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
1941 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1944 Value *LHSVal, *RHSVal;
1945 ConstantInt *LHSCst, *RHSCst;
1946 Instruction::BinaryOps LHSCC, RHSCC;
1947 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1948 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1949 if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
1950 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1951 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1952 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1953 // Ensure that the larger constant is on the RHS.
1954 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1955 SetCondInst *LHS = cast<SetCondInst>(Op0);
1956 if (cast<ConstantBool>(Cmp)->getValue()) {
1957 std::swap(LHS, RHS);
1958 std::swap(LHSCst, RHSCst);
1959 std::swap(LHSCC, RHSCC);
1962 // At this point, we know we have have two setcc instructions
1963 // comparing a value against two constants and or'ing the result
1964 // together. Because of the above check, we know that we only have
1965 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1966 // FoldSetCCLogical check above), that the two constants are not
1968 assert(LHSCst != RHSCst && "Compares not folded above?");
1971 default: assert(0 && "Unknown integer condition code!");
1972 case Instruction::SetEQ:
1974 default: assert(0 && "Unknown integer condition code!");
1975 case Instruction::SetEQ:
1976 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
1977 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1978 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
1979 LHSVal->getName()+".off");
1980 InsertNewInstBefore(Add, I);
1981 const Type *UnsType = Add->getType()->getUnsignedVersion();
1982 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
1983 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
1984 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1985 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1987 break; // (X == 13 | X == 15) -> no change
1989 case Instruction::SetGT: // (X == 13 | X > 14) -> no change
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::SetNE:
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);
2007 case Instruction::SetLT:
2009 default: assert(0 && "Unknown integer condition code!");
2010 case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
2012 case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
2013 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
2014 case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
2015 case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
2016 return ReplaceInstUsesWith(I, RHS);
2019 case Instruction::SetGT:
2021 default: assert(0 && "Unknown integer condition code!");
2022 case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
2023 case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
2024 return ReplaceInstUsesWith(I, LHS);
2025 case Instruction::SetNE: // (X > 13 | X != 15) -> true
2026 case Instruction::SetLT: // (X > 13 | X < 15) -> true
2027 return ReplaceInstUsesWith(I, ConstantBool::True);
2032 return Changed ? &I : 0;
2035 // XorSelf - Implements: X ^ X --> 0
2038 XorSelf(Value *rhs) : RHS(rhs) {}
2039 bool shouldApply(Value *LHS) const { return LHS == RHS; }
2040 Instruction *apply(BinaryOperator &Xor) const {
2046 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
2047 bool Changed = SimplifyCommutative(I);
2048 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2050 if (isa<UndefValue>(Op1))
2051 return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
2053 // xor X, X = 0, even if X is nested in a sequence of Xor's.
2054 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
2055 assert(Result == &I && "AssociativeOpt didn't work?");
2056 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
2059 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
2061 if (RHS->isNullValue())
2062 return ReplaceInstUsesWith(I, Op0);
2064 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2065 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
2066 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
2067 if (RHS == ConstantBool::True && SCI->hasOneUse())
2068 return new SetCondInst(SCI->getInverseCondition(),
2069 SCI->getOperand(0), SCI->getOperand(1));
2071 // ~(c-X) == X-c-1 == X+(-c-1)
2072 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
2073 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
2074 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
2075 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
2076 ConstantInt::get(I.getType(), 1));
2077 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
2080 // ~(~X & Y) --> (X | ~Y)
2081 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
2082 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
2083 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
2085 BinaryOperator::createNot(Op0I->getOperand(1),
2086 Op0I->getOperand(1)->getName()+".not");
2087 InsertNewInstBefore(NotY, I);
2088 return BinaryOperator::createOr(Op0NotVal, NotY);
2092 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
2093 switch (Op0I->getOpcode()) {
2094 case Instruction::Add:
2095 // ~(X-c) --> (-c-1)-X
2096 if (RHS->isAllOnesValue()) {
2097 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
2098 return BinaryOperator::createSub(
2099 ConstantExpr::getSub(NegOp0CI,
2100 ConstantInt::get(I.getType(), 1)),
2101 Op0I->getOperand(0));
2104 case Instruction::And:
2105 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
2106 if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue())
2107 return BinaryOperator::createOr(Op0, RHS);
2109 case Instruction::Or:
2110 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
2111 if (ConstantExpr::getAnd(RHS, Op0CI) == RHS)
2112 return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS));
2118 // Try to fold constant and into select arguments.
2119 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2120 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
2122 if (isa<PHINode>(Op0))
2123 if (Instruction *NV = FoldOpIntoPhi(I))
2127 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
2129 return ReplaceInstUsesWith(I,
2130 ConstantIntegral::getAllOnesValue(I.getType()));
2132 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
2134 return ReplaceInstUsesWith(I,
2135 ConstantIntegral::getAllOnesValue(I.getType()));
2137 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
2138 if (Op1I->getOpcode() == Instruction::Or) {
2139 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
2140 cast<BinaryOperator>(Op1I)->swapOperands();
2142 std::swap(Op0, Op1);
2143 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
2145 std::swap(Op0, Op1);
2147 } else if (Op1I->getOpcode() == Instruction::Xor) {
2148 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
2149 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
2150 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
2151 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
2154 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
2155 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
2156 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
2157 cast<BinaryOperator>(Op0I)->swapOperands();
2158 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
2159 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
2160 Op1->getName()+".not"), I);
2161 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
2163 } else if (Op0I->getOpcode() == Instruction::Xor) {
2164 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
2165 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
2166 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
2167 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
2170 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
2171 Value *A, *B; ConstantInt *C1, *C2;
2172 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
2173 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) &&
2174 ConstantExpr::getAnd(C1, C2)->isNullValue())
2175 return BinaryOperator::createOr(Op0, Op1);
2177 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
2178 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
2179 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
2182 return Changed ? &I : 0;
2185 /// MulWithOverflow - Compute Result = In1*In2, returning true if the result
2186 /// overflowed for this type.
2187 static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2189 Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
2190 return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
2193 static bool isPositive(ConstantInt *C) {
2194 return cast<ConstantSInt>(C)->getValue() >= 0;
2197 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
2198 /// overflowed for this type.
2199 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
2201 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
2203 if (In1->getType()->isUnsigned())
2204 return cast<ConstantUInt>(Result)->getValue() <
2205 cast<ConstantUInt>(In1)->getValue();
2206 if (isPositive(In1) != isPositive(In2))
2208 if (isPositive(In1))
2209 return cast<ConstantSInt>(Result)->getValue() <
2210 cast<ConstantSInt>(In1)->getValue();
2211 return cast<ConstantSInt>(Result)->getValue() >
2212 cast<ConstantSInt>(In1)->getValue();
2215 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
2216 /// code necessary to compute the offset from the base pointer (without adding
2217 /// in the base pointer). Return the result as a signed integer of intptr size.
2218 static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
2219 TargetData &TD = IC.getTargetData();
2220 gep_type_iterator GTI = gep_type_begin(GEP);
2221 const Type *UIntPtrTy = TD.getIntPtrType();
2222 const Type *SIntPtrTy = UIntPtrTy->getSignedVersion();
2223 Value *Result = Constant::getNullValue(SIntPtrTy);
2225 // Build a mask for high order bits.
2226 uint64_t PtrSizeMask = ~0ULL;
2227 PtrSizeMask >>= 64-(TD.getPointerSize()*8);
2229 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
2230 Value *Op = GEP->getOperand(i);
2231 uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask;
2232 Constant *Scale = ConstantExpr::getCast(ConstantUInt::get(UIntPtrTy, Size),
2234 if (Constant *OpC = dyn_cast<Constant>(Op)) {
2235 if (!OpC->isNullValue()) {
2236 OpC = ConstantExpr::getCast(OpC, SIntPtrTy);
2237 Scale = ConstantExpr::getMul(OpC, Scale);
2238 if (Constant *RC = dyn_cast<Constant>(Result))
2239 Result = ConstantExpr::getAdd(RC, Scale);
2241 // Emit an add instruction.
2242 Result = IC.InsertNewInstBefore(
2243 BinaryOperator::createAdd(Result, Scale,
2244 GEP->getName()+".offs"), I);
2248 // Convert to correct type.
2249 Op = IC.InsertNewInstBefore(new CastInst(Op, SIntPtrTy,
2250 Op->getName()+".c"), I);
2252 // We'll let instcombine(mul) convert this to a shl if possible.
2253 Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
2254 GEP->getName()+".idx"), I);
2256 // Emit an add instruction.
2257 Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
2258 GEP->getName()+".offs"), I);
2264 /// FoldGEPSetCC - Fold comparisons between a GEP instruction and something
2265 /// else. At this point we know that the GEP is on the LHS of the comparison.
2266 Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS,
2267 Instruction::BinaryOps Cond,
2269 assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
2271 if (CastInst *CI = dyn_cast<CastInst>(RHS))
2272 if (isa<PointerType>(CI->getOperand(0)->getType()))
2273 RHS = CI->getOperand(0);
2275 Value *PtrBase = GEPLHS->getOperand(0);
2276 if (PtrBase == RHS) {
2277 // As an optimization, we don't actually have to compute the actual value of
2278 // OFFSET if this is a seteq or setne comparison, just return whether each
2279 // index is zero or not.
2280 if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) {
2281 Instruction *InVal = 0;
2282 gep_type_iterator GTI = gep_type_begin(GEPLHS);
2283 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
2285 if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
2286 if (isa<UndefValue>(C)) // undef index -> undef.
2287 return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
2288 if (C->isNullValue())
2290 else if (TD->getTypeSize(GTI.getIndexedType()) == 0) {
2291 EmitIt = false; // This is indexing into a zero sized array?
2292 } else if (isa<ConstantInt>(C))
2293 return ReplaceInstUsesWith(I, // No comparison is needed here.
2294 ConstantBool::get(Cond == Instruction::SetNE));
2299 new SetCondInst(Cond, GEPLHS->getOperand(i),
2300 Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
2304 InVal = InsertNewInstBefore(InVal, I);
2305 InsertNewInstBefore(Comp, I);
2306 if (Cond == Instruction::SetNE) // True if any are unequal
2307 InVal = BinaryOperator::createOr(InVal, Comp);
2308 else // True if all are equal
2309 InVal = BinaryOperator::createAnd(InVal, Comp);
2317 ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0
2318 ConstantBool::get(Cond == Instruction::SetEQ));
2321 // Only lower this if the setcc is the only user of the GEP or if we expect
2322 // the result to fold to a constant!
2323 if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
2324 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
2325 Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
2326 return new SetCondInst(Cond, Offset,
2327 Constant::getNullValue(Offset->getType()));
2329 } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
2330 // If the base pointers are different, but the indices are the same, just
2331 // compare the base pointer.
2332 if (PtrBase != GEPRHS->getOperand(0)) {
2333 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
2334 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
2335 GEPRHS->getOperand(0)->getType();
2337 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2338 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2339 IndicesTheSame = false;
2343 // If all indices are the same, just compare the base pointers.
2345 return new SetCondInst(Cond, GEPLHS->getOperand(0),
2346 GEPRHS->getOperand(0));
2348 // Otherwise, the base pointers are different and the indices are
2349 // different, bail out.
2353 // If one of the GEPs has all zero indices, recurse.
2354 bool AllZeros = true;
2355 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
2356 if (!isa<Constant>(GEPLHS->getOperand(i)) ||
2357 !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
2362 return FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0),
2363 SetCondInst::getSwappedCondition(Cond), I);
2365 // If the other GEP has all zero indices, recurse.
2367 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2368 if (!isa<Constant>(GEPRHS->getOperand(i)) ||
2369 !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
2374 return FoldGEPSetCC(GEPLHS, GEPRHS->getOperand(0), Cond, I);
2376 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
2377 // If the GEPs only differ by one index, compare it.
2378 unsigned NumDifferences = 0; // Keep track of # differences.
2379 unsigned DiffOperand = 0; // The operand that differs.
2380 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
2381 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
2382 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
2383 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
2384 // Irreconcilable differences.
2388 if (NumDifferences++) break;
2393 if (NumDifferences == 0) // SAME GEP?
2394 return ReplaceInstUsesWith(I, // No comparison is needed here.
2395 ConstantBool::get(Cond == Instruction::SetEQ));
2396 else if (NumDifferences == 1) {
2397 Value *LHSV = GEPLHS->getOperand(DiffOperand);
2398 Value *RHSV = GEPRHS->getOperand(DiffOperand);
2400 // Convert the operands to signed values to make sure to perform a
2401 // signed comparison.
2402 const Type *NewTy = LHSV->getType()->getSignedVersion();
2403 if (LHSV->getType() != NewTy)
2404 LHSV = InsertNewInstBefore(new CastInst(LHSV, NewTy,
2405 LHSV->getName()), I);
2406 if (RHSV->getType() != NewTy)
2407 RHSV = InsertNewInstBefore(new CastInst(RHSV, NewTy,
2408 RHSV->getName()), I);
2409 return new SetCondInst(Cond, LHSV, RHSV);
2413 // Only lower this if the setcc is the only user of the GEP or if we expect
2414 // the result to fold to a constant!
2415 if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
2416 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
2417 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
2418 Value *L = EmitGEPOffset(GEPLHS, I, *this);
2419 Value *R = EmitGEPOffset(GEPRHS, I, *this);
2420 return new SetCondInst(Cond, L, R);
2427 Instruction *InstCombiner::visitSetCondInst(SetCondInst &I) {
2428 bool Changed = SimplifyCommutative(I);
2429 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2430 const Type *Ty = Op0->getType();
2434 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
2436 if (isa<UndefValue>(Op1)) // X setcc undef -> undef
2437 return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
2439 // setcc <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
2440 // addresses never equal each other! We already know that Op0 != Op1.
2441 if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
2442 isa<ConstantPointerNull>(Op0)) &&
2443 (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
2444 isa<ConstantPointerNull>(Op1)))
2445 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
2447 // setcc's with boolean values can always be turned into bitwise operations
2448 if (Ty == Type::BoolTy) {
2449 switch (I.getOpcode()) {
2450 default: assert(0 && "Invalid setcc instruction!");
2451 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
2452 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
2453 InsertNewInstBefore(Xor, I);
2454 return BinaryOperator::createNot(Xor);
2456 case Instruction::SetNE:
2457 return BinaryOperator::createXor(Op0, Op1);
2459 case Instruction::SetGT:
2460 std::swap(Op0, Op1); // Change setgt -> setlt
2462 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
2463 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2464 InsertNewInstBefore(Not, I);
2465 return BinaryOperator::createAnd(Not, Op1);
2467 case Instruction::SetGE:
2468 std::swap(Op0, Op1); // Change setge -> setle
2470 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
2471 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
2472 InsertNewInstBefore(Not, I);
2473 return BinaryOperator::createOr(Not, Op1);
2478 // See if we are doing a comparison between a constant and an instruction that
2479 // can be folded into the comparison.
2480 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2481 // Check to see if we are comparing against the minimum or maximum value...
2482 if (CI->isMinValue()) {
2483 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
2484 return ReplaceInstUsesWith(I, ConstantBool::False);
2485 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
2486 return ReplaceInstUsesWith(I, ConstantBool::True);
2487 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
2488 return BinaryOperator::createSetEQ(Op0, Op1);
2489 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
2490 return BinaryOperator::createSetNE(Op0, Op1);
2492 } else if (CI->isMaxValue()) {
2493 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
2494 return ReplaceInstUsesWith(I, ConstantBool::False);
2495 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
2496 return ReplaceInstUsesWith(I, ConstantBool::True);
2497 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
2498 return BinaryOperator::createSetEQ(Op0, Op1);
2499 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
2500 return BinaryOperator::createSetNE(Op0, Op1);
2502 // Comparing against a value really close to min or max?
2503 } else if (isMinValuePlusOne(CI)) {
2504 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
2505 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
2506 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
2507 return BinaryOperator::createSetNE(Op0, SubOne(CI));
2509 } else if (isMaxValueMinusOne(CI)) {
2510 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
2511 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
2512 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
2513 return BinaryOperator::createSetNE(Op0, AddOne(CI));
2516 // If we still have a setle or setge instruction, turn it into the
2517 // appropriate setlt or setgt instruction. Since the border cases have
2518 // already been handled above, this requires little checking.
2520 if (I.getOpcode() == Instruction::SetLE)
2521 return BinaryOperator::createSetLT(Op0, AddOne(CI));
2522 if (I.getOpcode() == Instruction::SetGE)
2523 return BinaryOperator::createSetGT(Op0, SubOne(CI));
2525 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
2526 switch (LHSI->getOpcode()) {
2527 case Instruction::And:
2528 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
2529 LHSI->getOperand(0)->hasOneUse()) {
2530 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
2531 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
2532 // happens a LOT in code produced by the C front-end, for bitfield
2534 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
2535 ConstantUInt *ShAmt;
2536 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
2537 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
2538 const Type *Ty = LHSI->getType();
2540 // We can fold this as long as we can't shift unknown bits
2541 // into the mask. This can only happen with signed shift
2542 // rights, as they sign-extend.
2544 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
2545 Shift->getType()->isUnsigned();
2547 // To test for the bad case of the signed shr, see if any
2548 // of the bits shifted in could be tested after the mask.
2549 int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue();
2550 if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
2552 Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal);
2554 ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
2555 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
2561 if (Shift->getOpcode() == Instruction::Shl)
2562 NewCst = ConstantExpr::getUShr(CI, ShAmt);
2564 NewCst = ConstantExpr::getShl(CI, ShAmt);
2566 // Check to see if we are shifting out any of the bits being
2568 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
2569 // If we shifted bits out, the fold is not going to work out.
2570 // As a special case, check to see if this means that the
2571 // result is always true or false now.
2572 if (I.getOpcode() == Instruction::SetEQ)
2573 return ReplaceInstUsesWith(I, ConstantBool::False);
2574 if (I.getOpcode() == Instruction::SetNE)
2575 return ReplaceInstUsesWith(I, ConstantBool::True);
2577 I.setOperand(1, NewCst);
2578 Constant *NewAndCST;
2579 if (Shift->getOpcode() == Instruction::Shl)
2580 NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
2582 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
2583 LHSI->setOperand(1, NewAndCST);
2584 LHSI->setOperand(0, Shift->getOperand(0));
2585 WorkList.push_back(Shift); // Shift is dead.
2586 AddUsesToWorkList(I);
2594 case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
2595 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2596 switch (I.getOpcode()) {
2598 case Instruction::SetEQ:
2599 case Instruction::SetNE: {
2600 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2602 // Check that the shift amount is in range. If not, don't perform
2603 // undefined shifts. When the shift is visited it will be
2605 if (ShAmt->getValue() >= TypeBits)
2608 // If we are comparing against bits always shifted out, the
2609 // comparison cannot succeed.
2611 ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
2612 if (Comp != CI) {// Comparing against a bit that we know is zero.
2613 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2614 Constant *Cst = ConstantBool::get(IsSetNE);
2615 return ReplaceInstUsesWith(I, Cst);
2618 if (LHSI->hasOneUse()) {
2619 // Otherwise strength reduce the shift into an and.
2620 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2621 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
2624 if (CI->getType()->isUnsigned()) {
2625 Mask = ConstantUInt::get(CI->getType(), Val);
2626 } else if (ShAmtVal != 0) {
2627 Mask = ConstantSInt::get(CI->getType(), Val);
2629 Mask = ConstantInt::getAllOnesValue(CI->getType());
2633 BinaryOperator::createAnd(LHSI->getOperand(0),
2634 Mask, LHSI->getName()+".mask");
2635 Value *And = InsertNewInstBefore(AndI, I);
2636 return new SetCondInst(I.getOpcode(), And,
2637 ConstantExpr::getUShr(CI, ShAmt));
2644 case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
2645 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2646 switch (I.getOpcode()) {
2648 case Instruction::SetEQ:
2649 case Instruction::SetNE: {
2651 // Check that the shift amount is in range. If not, don't perform
2652 // undefined shifts. When the shift is visited it will be
2654 unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
2655 if (ShAmt->getValue() >= TypeBits)
2658 // If we are comparing against bits always shifted out, the
2659 // comparison cannot succeed.
2661 ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
2663 if (Comp != CI) {// Comparing against a bit that we know is zero.
2664 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2665 Constant *Cst = ConstantBool::get(IsSetNE);
2666 return ReplaceInstUsesWith(I, Cst);
2669 if (LHSI->hasOneUse() || CI->isNullValue()) {
2670 unsigned ShAmtVal = (unsigned)ShAmt->getValue();
2672 // Otherwise strength reduce the shift into an and.
2673 uint64_t Val = ~0ULL; // All ones.
2674 Val <<= ShAmtVal; // Shift over to the right spot.
2677 if (CI->getType()->isUnsigned()) {
2678 Val &= ~0ULL >> (64-TypeBits);
2679 Mask = ConstantUInt::get(CI->getType(), Val);
2681 Mask = ConstantSInt::get(CI->getType(), Val);
2685 BinaryOperator::createAnd(LHSI->getOperand(0),
2686 Mask, LHSI->getName()+".mask");
2687 Value *And = InsertNewInstBefore(AndI, I);
2688 return new SetCondInst(I.getOpcode(), And,
2689 ConstantExpr::getShl(CI, ShAmt));
2697 case Instruction::Div:
2698 // Fold: (div X, C1) op C2 -> range check
2699 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
2700 // Fold this div into the comparison, producing a range check.
2701 // Determine, based on the divide type, what the range is being
2702 // checked. If there is an overflow on the low or high side, remember
2703 // it, otherwise compute the range [low, hi) bounding the new value.
2704 bool LoOverflow = false, HiOverflow = 0;
2705 ConstantInt *LoBound = 0, *HiBound = 0;
2708 bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
2710 Instruction::BinaryOps Opcode = I.getOpcode();
2712 if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
2713 } else if (LHSI->getType()->isUnsigned()) { // udiv
2715 LoOverflow = ProdOV;
2716 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
2717 } else if (isPositive(DivRHS)) { // Divisor is > 0.
2718 if (CI->isNullValue()) { // (X / pos) op 0
2720 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
2722 } else if (isPositive(CI)) { // (X / pos) op pos
2724 LoOverflow = ProdOV;
2725 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
2726 } else { // (X / pos) op neg
2727 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
2728 LoOverflow = AddWithOverflow(LoBound, Prod,
2729 cast<ConstantInt>(DivRHSH));
2731 HiOverflow = ProdOV;
2733 } else { // Divisor is < 0.
2734 if (CI->isNullValue()) { // (X / neg) op 0
2735 LoBound = AddOne(DivRHS);
2736 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
2737 if (HiBound == DivRHS)
2738 LoBound = 0; // - INTMIN = INTMIN
2739 } else if (isPositive(CI)) { // (X / neg) op pos
2740 HiOverflow = LoOverflow = ProdOV;
2742 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
2743 HiBound = AddOne(Prod);
2744 } else { // (X / neg) op neg
2746 LoOverflow = HiOverflow = ProdOV;
2747 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
2750 // Dividing by a negate swaps the condition.
2751 Opcode = SetCondInst::getSwappedCondition(Opcode);
2755 Value *X = LHSI->getOperand(0);
2757 default: assert(0 && "Unhandled setcc opcode!");
2758 case Instruction::SetEQ:
2759 if (LoOverflow && HiOverflow)
2760 return ReplaceInstUsesWith(I, ConstantBool::False);
2761 else if (HiOverflow)
2762 return new SetCondInst(Instruction::SetGE, X, LoBound);
2763 else if (LoOverflow)
2764 return new SetCondInst(Instruction::SetLT, X, HiBound);
2766 return InsertRangeTest(X, LoBound, HiBound, true, I);
2767 case Instruction::SetNE:
2768 if (LoOverflow && HiOverflow)
2769 return ReplaceInstUsesWith(I, ConstantBool::True);
2770 else if (HiOverflow)
2771 return new SetCondInst(Instruction::SetLT, X, LoBound);
2772 else if (LoOverflow)
2773 return new SetCondInst(Instruction::SetGE, X, HiBound);
2775 return InsertRangeTest(X, LoBound, HiBound, false, I);
2776 case Instruction::SetLT:
2778 return ReplaceInstUsesWith(I, ConstantBool::False);
2779 return new SetCondInst(Instruction::SetLT, X, LoBound);
2780 case Instruction::SetGT:
2782 return ReplaceInstUsesWith(I, ConstantBool::False);
2783 return new SetCondInst(Instruction::SetGE, X, HiBound);
2790 // Simplify seteq and setne instructions...
2791 if (I.getOpcode() == Instruction::SetEQ ||
2792 I.getOpcode() == Instruction::SetNE) {
2793 bool isSetNE = I.getOpcode() == Instruction::SetNE;
2795 // If the first operand is (and|or|xor) with a constant, and the second
2796 // operand is a constant, simplify a bit.
2797 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
2798 switch (BO->getOpcode()) {
2799 case Instruction::Rem:
2800 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
2801 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
2803 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1) {
2804 int64_t V = cast<ConstantSInt>(BO->getOperand(1))->getValue();
2805 if (isPowerOf2_64(V)) {
2806 unsigned L2 = Log2_64(V);
2807 const Type *UTy = BO->getType()->getUnsignedVersion();
2808 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
2810 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
2811 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
2812 RHSCst, BO->getName()), I);
2813 return BinaryOperator::create(I.getOpcode(), NewRem,
2814 Constant::getNullValue(UTy));
2819 case Instruction::Add:
2820 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
2821 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2822 if (BO->hasOneUse())
2823 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
2824 ConstantExpr::getSub(CI, BOp1C));
2825 } else if (CI->isNullValue()) {
2826 // Replace ((add A, B) != 0) with (A != -B) if A or B is
2827 // efficiently invertible, or if the add has just this one use.
2828 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
2830 if (Value *NegVal = dyn_castNegVal(BOp1))
2831 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
2832 else if (Value *NegVal = dyn_castNegVal(BOp0))
2833 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
2834 else if (BO->hasOneUse()) {
2835 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
2837 InsertNewInstBefore(Neg, I);
2838 return new SetCondInst(I.getOpcode(), BOp0, Neg);
2842 case Instruction::Xor:
2843 // For the xor case, we can xor two constants together, eliminating
2844 // the explicit xor.
2845 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
2846 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
2847 ConstantExpr::getXor(CI, BOC));
2850 case Instruction::Sub:
2851 // Replace (([sub|xor] A, B) != 0) with (A != B)
2852 if (CI->isNullValue())
2853 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
2857 case Instruction::Or:
2858 // If bits are being or'd in that are not present in the constant we
2859 // are comparing against, then the comparison could never succeed!
2860 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
2861 Constant *NotCI = ConstantExpr::getNot(CI);
2862 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
2863 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
2867 case Instruction::And:
2868 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2869 // If bits are being compared against that are and'd out, then the
2870 // comparison can never succeed!
2871 if (!ConstantExpr::getAnd(CI,
2872 ConstantExpr::getNot(BOC))->isNullValue())
2873 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
2875 // If we have ((X & C) == C), turn it into ((X & C) != 0).
2876 if (CI == BOC && isOneBitSet(CI))
2877 return new SetCondInst(isSetNE ? Instruction::SetEQ :
2878 Instruction::SetNE, Op0,
2879 Constant::getNullValue(CI->getType()));
2881 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
2882 // to be a signed value as appropriate.
2883 if (isSignBit(BOC)) {
2884 Value *X = BO->getOperand(0);
2885 // If 'X' is not signed, insert a cast now...
2886 if (!BOC->getType()->isSigned()) {
2887 const Type *DestTy = BOC->getType()->getSignedVersion();
2888 X = InsertCastBefore(X, DestTy, I);
2890 return new SetCondInst(isSetNE ? Instruction::SetLT :
2891 Instruction::SetGE, X,
2892 Constant::getNullValue(X->getType()));
2895 // ((X & ~7) == 0) --> X < 8
2896 if (CI->isNullValue() && isHighOnes(BOC)) {
2897 Value *X = BO->getOperand(0);
2898 Constant *NegX = ConstantExpr::getNeg(BOC);
2900 // If 'X' is signed, insert a cast now.
2901 if (NegX->getType()->isSigned()) {
2902 const Type *DestTy = NegX->getType()->getUnsignedVersion();
2903 X = InsertCastBefore(X, DestTy, I);
2904 NegX = ConstantExpr::getCast(NegX, DestTy);
2907 return new SetCondInst(isSetNE ? Instruction::SetGE :
2908 Instruction::SetLT, X, NegX);
2915 } else { // Not a SetEQ/SetNE
2916 // If the LHS is a cast from an integral value of the same size,
2917 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
2918 Value *CastOp = Cast->getOperand(0);
2919 const Type *SrcTy = CastOp->getType();
2920 unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits();
2921 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
2922 SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
2923 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
2924 "Source and destination signednesses should differ!");
2925 if (Cast->getType()->isSigned()) {
2926 // If this is a signed comparison, check for comparisons in the
2927 // vicinity of zero.
2928 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
2930 return BinaryOperator::createSetGT(CastOp,
2931 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize-1))-1));
2932 else if (I.getOpcode() == Instruction::SetGT &&
2933 cast<ConstantSInt>(CI)->getValue() == -1)
2934 // X > -1 => x < 128
2935 return BinaryOperator::createSetLT(CastOp,
2936 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize-1)));
2938 ConstantUInt *CUI = cast<ConstantUInt>(CI);
2939 if (I.getOpcode() == Instruction::SetLT &&
2940 CUI->getValue() == 1ULL << (SrcTySize-1))
2941 // X < 128 => X > -1
2942 return BinaryOperator::createSetGT(CastOp,
2943 ConstantSInt::get(SrcTy, -1));
2944 else if (I.getOpcode() == Instruction::SetGT &&
2945 CUI->getValue() == (1ULL << (SrcTySize-1))-1)
2947 return BinaryOperator::createSetLT(CastOp,
2948 Constant::getNullValue(SrcTy));
2955 // Handle setcc with constant RHS's that can be integer, FP or pointer.
2956 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
2957 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
2958 switch (LHSI->getOpcode()) {
2959 case Instruction::GetElementPtr:
2960 if (RHSC->isNullValue()) {
2961 // Transform setcc GEP P, int 0, int 0, int 0, null -> setcc P, null
2962 bool isAllZeros = true;
2963 for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
2964 if (!isa<Constant>(LHSI->getOperand(i)) ||
2965 !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
2970 return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),
2971 Constant::getNullValue(LHSI->getOperand(0)->getType()));
2975 case Instruction::PHI:
2976 if (Instruction *NV = FoldOpIntoPhi(I))
2979 case Instruction::Select:
2980 // If either operand of the select is a constant, we can fold the
2981 // comparison into the select arms, which will cause one to be
2982 // constant folded and the select turned into a bitwise or.
2983 Value *Op1 = 0, *Op2 = 0;
2984 if (LHSI->hasOneUse()) {
2985 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
2986 // Fold the known value into the constant operand.
2987 Op1 = ConstantExpr::get(I.getOpcode(), C, RHSC);
2988 // Insert a new SetCC of the other select operand.
2989 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
2990 LHSI->getOperand(2), RHSC,
2992 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
2993 // Fold the known value into the constant operand.
2994 Op2 = ConstantExpr::get(I.getOpcode(), C, RHSC);
2995 // Insert a new SetCC of the other select operand.
2996 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
2997 LHSI->getOperand(1), RHSC,
3003 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
3008 // If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now.
3009 if (User *GEP = dyn_castGetElementPtr(Op0))
3010 if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I))
3012 if (User *GEP = dyn_castGetElementPtr(Op1))
3013 if (Instruction *NI = FoldGEPSetCC(GEP, Op0,
3014 SetCondInst::getSwappedCondition(I.getOpcode()), I))
3017 // Test to see if the operands of the setcc are casted versions of other
3018 // values. If the cast can be stripped off both arguments, we do so now.
3019 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3020 Value *CastOp0 = CI->getOperand(0);
3021 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
3022 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
3023 (I.getOpcode() == Instruction::SetEQ ||
3024 I.getOpcode() == Instruction::SetNE)) {
3025 // We keep moving the cast from the left operand over to the right
3026 // operand, where it can often be eliminated completely.
3029 // If operand #1 is a cast instruction, see if we can eliminate it as
3031 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
3032 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
3034 Op1 = CI2->getOperand(0);
3036 // If Op1 is a constant, we can fold the cast into the constant.
3037 if (Op1->getType() != Op0->getType())
3038 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
3039 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
3041 // Otherwise, cast the RHS right before the setcc
3042 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
3043 InsertNewInstBefore(cast<Instruction>(Op1), I);
3045 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
3048 // Handle the special case of: setcc (cast bool to X), <cst>
3049 // This comes up when you have code like
3052 // For generality, we handle any zero-extension of any operand comparison
3053 // with a constant or another cast from the same type.
3054 if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
3055 if (Instruction *R = visitSetCondInstWithCastAndCast(I))
3058 return Changed ? &I : 0;
3061 // visitSetCondInstWithCastAndCast - Handle setcond (cast x to y), (cast/cst).
3062 // We only handle extending casts so far.
3064 Instruction *InstCombiner::visitSetCondInstWithCastAndCast(SetCondInst &SCI) {
3065 Value *LHSCIOp = cast<CastInst>(SCI.getOperand(0))->getOperand(0);
3066 const Type *SrcTy = LHSCIOp->getType();
3067 const Type *DestTy = SCI.getOperand(0)->getType();
3070 if (!DestTy->isIntegral() || !SrcTy->isIntegral())
3073 unsigned SrcBits = SrcTy->getPrimitiveSizeInBits();
3074 unsigned DestBits = DestTy->getPrimitiveSizeInBits();
3075 if (SrcBits >= DestBits) return 0; // Only handle extending cast.
3077 // Is this a sign or zero extension?
3078 bool isSignSrc = SrcTy->isSigned();
3079 bool isSignDest = DestTy->isSigned();
3081 if (CastInst *CI = dyn_cast<CastInst>(SCI.getOperand(1))) {
3082 // Not an extension from the same type?
3083 RHSCIOp = CI->getOperand(0);
3084 if (RHSCIOp->getType() != LHSCIOp->getType()) return 0;
3085 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(SCI.getOperand(1))) {
3086 // Compute the constant that would happen if we truncated to SrcTy then
3087 // reextended to DestTy.
3088 Constant *Res = ConstantExpr::getCast(CI, SrcTy);
3090 if (ConstantExpr::getCast(Res, DestTy) == CI) {
3093 // If the value cannot be represented in the shorter type, we cannot emit
3094 // a simple comparison.
3095 if (SCI.getOpcode() == Instruction::SetEQ)
3096 return ReplaceInstUsesWith(SCI, ConstantBool::False);
3097 if (SCI.getOpcode() == Instruction::SetNE)
3098 return ReplaceInstUsesWith(SCI, ConstantBool::True);
3100 // Evaluate the comparison for LT.
3102 if (DestTy->isSigned()) {
3103 // We're performing a signed comparison.
3105 // Signed extend and signed comparison.
3106 if (cast<ConstantSInt>(CI)->getValue() < 0) // X < (small) --> false
3107 Result = ConstantBool::False;
3109 Result = ConstantBool::True; // X < (large) --> true
3111 // Unsigned extend and signed comparison.
3112 if (cast<ConstantSInt>(CI)->getValue() < 0)
3113 Result = ConstantBool::False;
3115 Result = ConstantBool::True;
3118 // We're performing an unsigned comparison.
3120 // Unsigned extend & compare -> always true.
3121 Result = ConstantBool::True;
3123 // We're performing an unsigned comp with a sign extended value.
3124 // This is true if the input is >= 0. [aka >s -1]
3125 Constant *NegOne = ConstantIntegral::getAllOnesValue(SrcTy);
3126 Result = InsertNewInstBefore(BinaryOperator::createSetGT(LHSCIOp,
3127 NegOne, SCI.getName()), SCI);
3131 // Finally, return the value computed.
3132 if (SCI.getOpcode() == Instruction::SetLT) {
3133 return ReplaceInstUsesWith(SCI, Result);
3135 assert(SCI.getOpcode()==Instruction::SetGT &&"SetCC should be folded!");
3136 if (Constant *CI = dyn_cast<Constant>(Result))
3137 return ReplaceInstUsesWith(SCI, ConstantExpr::getNot(CI));
3139 return BinaryOperator::createNot(Result);
3146 // Okay, just insert a compare of the reduced operands now!
3147 return BinaryOperator::create(SCI.getOpcode(), LHSCIOp, RHSCIOp);
3150 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
3151 assert(I.getOperand(1)->getType() == Type::UByteTy);
3152 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3153 bool isLeftShift = I.getOpcode() == Instruction::Shl;
3155 // shl X, 0 == X and shr X, 0 == X
3156 // shl 0, X == 0 and shr 0, X == 0
3157 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
3158 Op0 == Constant::getNullValue(Op0->getType()))
3159 return ReplaceInstUsesWith(I, Op0);
3161 if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
3162 if (!isLeftShift && I.getType()->isSigned())
3163 return ReplaceInstUsesWith(I, Op0);
3164 else // undef << X -> 0 AND undef >>u X -> 0
3165 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3167 if (isa<UndefValue>(Op1)) {
3168 if (isLeftShift || I.getType()->isUnsigned())// X << undef, X >>u undef -> 0
3169 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
3171 return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X
3174 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
3176 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
3177 if (CSI->isAllOnesValue())
3178 return ReplaceInstUsesWith(I, CSI);
3180 // Try to fold constant and into select arguments.
3181 if (isa<Constant>(Op0))
3182 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
3183 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3186 // See if we can turn a signed shr into an unsigned shr.
3187 if (!isLeftShift && I.getType()->isSigned()) {
3188 if (MaskedValueIsZero(Op0, ConstantInt::getMinValue(I.getType()))) {
3189 Value *V = InsertCastBefore(Op0, I.getType()->getUnsignedVersion(), I);
3190 V = InsertNewInstBefore(new ShiftInst(Instruction::Shr, V, Op1,
3192 return new CastInst(V, I.getType());
3196 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
3197 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
3198 // of a signed value.
3200 unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits();
3201 if (CUI->getValue() >= TypeBits) {
3202 if (!Op0->getType()->isSigned() || isLeftShift)
3203 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
3205 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
3210 // ((X*C1) << C2) == (X * (C1 << C2))
3211 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
3212 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
3213 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
3214 return BinaryOperator::createMul(BO->getOperand(0),
3215 ConstantExpr::getShl(BOOp, CUI));
3217 // Try to fold constant and into select arguments.
3218 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
3219 if (Instruction *R = FoldOpIntoSelect(I, SI, this))
3221 if (isa<PHINode>(Op0))
3222 if (Instruction *NV = FoldOpIntoPhi(I))
3225 if (Op0->hasOneUse()) {
3226 // If this is a SHL of a sign-extending cast, see if we can turn the input
3227 // into a zero extending cast (a simple strength reduction).
3228 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
3229 const Type *SrcTy = CI->getOperand(0)->getType();
3230 if (isLeftShift && SrcTy->isInteger() && SrcTy->isSigned() &&
3231 SrcTy->getPrimitiveSizeInBits() <
3232 CI->getType()->getPrimitiveSizeInBits()) {
3233 // We can change it to a zero extension if we are shifting out all of
3234 // the sign extended bits. To check this, form a mask of all of the
3235 // sign extend bits, then shift them left and see if we have anything
3237 Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); // 1111
3238 Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); // 00001111
3239 Mask = ConstantExpr::getNot(Mask); // 1's in the sign bits: 11110000
3240 if (ConstantExpr::getShl(Mask, CUI)->isNullValue()) {
3241 // If the shift is nuking all of the sign bits, change this to a
3242 // zero extension cast. To do this, cast the cast input to
3243 // unsigned, then to the requested size.
3244 Value *CastOp = CI->getOperand(0);
3246 new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
3247 CI->getName()+".uns");
3248 NC = InsertNewInstBefore(NC, I);
3249 // Finally, insert a replacement for CI.
3250 NC = new CastInst(NC, CI->getType(), CI->getName());
3252 NC = InsertNewInstBefore(NC, I);
3253 WorkList.push_back(CI); // Delete CI later.
3254 I.setOperand(0, NC);
3255 return &I; // The SHL operand was modified.
3260 // If the operand is an bitwise operator with a constant RHS, and the
3261 // shift is the only use, we can pull it out of the shift.
3262 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0))
3263 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
3264 bool isValid = true; // Valid only for And, Or, Xor
3265 bool highBitSet = false; // Transform if high bit of constant set?
3267 switch (Op0BO->getOpcode()) {
3268 default: isValid = false; break; // Do not perform transform!
3269 case Instruction::Add:
3270 isValid = isLeftShift;
3272 case Instruction::Or:
3273 case Instruction::Xor:
3276 case Instruction::And:
3281 // If this is a signed shift right, and the high bit is modified
3282 // by the logical operation, do not perform the transformation.
3283 // The highBitSet boolean indicates the value of the high bit of
3284 // the constant which would cause it to be modified for this
3287 if (isValid && !isLeftShift && !I.getType()->isUnsigned()) {
3288 uint64_t Val = Op0C->getRawValue();
3289 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
3293 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI);
3295 Instruction *NewShift =
3296 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI,
3299 InsertNewInstBefore(NewShift, I);
3301 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
3307 // If this is a shift of a shift, see if we can fold the two together...
3308 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
3309 if (ConstantUInt *ShiftAmt1C =
3310 dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) {
3311 unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getValue();
3312 unsigned ShiftAmt2 = (unsigned)CUI->getValue();
3314 // Check for (A << c1) << c2 and (A >> c1) >> c2
3315 if (I.getOpcode() == Op0SI->getOpcode()) {
3316 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
3317 if (Op0->getType()->getPrimitiveSizeInBits() < Amt)
3318 Amt = Op0->getType()->getPrimitiveSizeInBits();
3319 return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
3320 ConstantUInt::get(Type::UByteTy, Amt));
3323 // Check for (A << c1) >> c2 or visaversa. If we are dealing with
3324 // signed types, we can only support the (A >> c1) << c2 configuration,
3325 // because it can not turn an arbitrary bit of A into a sign bit.
3326 if (I.getType()->isUnsigned() || isLeftShift) {
3327 // Calculate bitmask for what gets shifted off the edge...
3328 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
3330 C = ConstantExpr::getShl(C, ShiftAmt1C);
3332 C = ConstantExpr::getShr(C, ShiftAmt1C);
3335 BinaryOperator::createAnd(Op0SI->getOperand(0), C,
3336 Op0SI->getOperand(0)->getName()+".mask");
3337 InsertNewInstBefore(Mask, I);
3339 // Figure out what flavor of shift we should use...
3340 if (ShiftAmt1 == ShiftAmt2)
3341 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
3342 else if (ShiftAmt1 < ShiftAmt2) {
3343 return new ShiftInst(I.getOpcode(), Mask,
3344 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
3346 return new ShiftInst(Op0SI->getOpcode(), Mask,
3347 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
3363 /// getCastType - In the future, we will split the cast instruction into these
3364 /// various types. Until then, we have to do the analysis here.
3365 static CastType getCastType(const Type *Src, const Type *Dest) {
3366 assert(Src->isIntegral() && Dest->isIntegral() &&
3367 "Only works on integral types!");
3368 unsigned SrcSize = Src->getPrimitiveSizeInBits();
3369 unsigned DestSize = Dest->getPrimitiveSizeInBits();
3371 if (SrcSize == DestSize) return Noop;
3372 if (SrcSize > DestSize) return Truncate;
3373 if (Src->isSigned()) return Signext;
3378 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
3381 static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
3382 const Type *DstTy, TargetData *TD) {
3384 // It is legal to eliminate the instruction if casting A->B->A if the sizes
3385 // are identical and the bits don't get reinterpreted (for example
3386 // int->float->int would not be allowed).
3387 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
3390 // If we are casting between pointer and integer types, treat pointers as
3391 // integers of the appropriate size for the code below.
3392 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
3393 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
3394 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
3396 // Allow free casting and conversion of sizes as long as the sign doesn't
3398 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
3399 CastType FirstCast = getCastType(SrcTy, MidTy);
3400 CastType SecondCast = getCastType(MidTy, DstTy);
3402 // Capture the effect of these two casts. If the result is a legal cast,
3403 // the CastType is stored here, otherwise a special code is used.
3404 static const unsigned CastResult[] = {
3405 // First cast is noop
3407 // First cast is a truncate
3408 1, 1, 4, 4, // trunc->extend is not safe to eliminate
3409 // First cast is a sign ext
3410 2, 5, 2, 4, // signext->zeroext never ok
3411 // First cast is a zero ext
3415 unsigned Result = CastResult[FirstCast*4+SecondCast];
3417 default: assert(0 && "Illegal table value!");
3422 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
3423 // truncates, we could eliminate more casts.
3424 return (unsigned)getCastType(SrcTy, DstTy) == Result;
3426 return false; // Not possible to eliminate this here.
3428 // Sign or zero extend followed by truncate is always ok if the result
3429 // is a truncate or noop.
3430 CastType ResultCast = getCastType(SrcTy, DstTy);
3431 if (ResultCast == Noop || ResultCast == Truncate)
3433 // Otherwise we are still growing the value, we are only safe if the
3434 // result will match the sign/zeroextendness of the result.
3435 return ResultCast == FirstCast;
3441 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
3442 if (V->getType() == Ty || isa<Constant>(V)) return false;
3443 if (const CastInst *CI = dyn_cast<CastInst>(V))
3444 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
3450 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
3451 /// InsertBefore instruction. This is specialized a bit to avoid inserting
3452 /// casts that are known to not do anything...
3454 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
3455 Instruction *InsertBefore) {
3456 if (V->getType() == DestTy) return V;
3457 if (Constant *C = dyn_cast<Constant>(V))
3458 return ConstantExpr::getCast(C, DestTy);
3460 CastInst *CI = new CastInst(V, DestTy, V->getName());
3461 InsertNewInstBefore(CI, *InsertBefore);
3465 // CastInst simplification
3467 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
3468 Value *Src = CI.getOperand(0);
3470 // If the user is casting a value to the same type, eliminate this cast
3472 if (CI.getType() == Src->getType())
3473 return ReplaceInstUsesWith(CI, Src);
3475 if (isa<UndefValue>(Src)) // cast undef -> undef
3476 return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
3478 // If casting the result of another cast instruction, try to eliminate this
3481 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
3482 Value *A = CSrc->getOperand(0);
3483 if (isEliminableCastOfCast(A->getType(), CSrc->getType(),
3484 CI.getType(), TD)) {
3485 // This instruction now refers directly to the cast's src operand. This
3486 // has a good chance of making CSrc dead.
3487 CI.setOperand(0, CSrc->getOperand(0));
3491 // If this is an A->B->A cast, and we are dealing with integral types, try
3492 // to convert this into a logical 'and' instruction.
3494 if (A->getType()->isInteger() &&
3495 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
3496 CSrc->getType()->isUnsigned() && // B->A cast must zero extend
3497 CSrc->getType()->getPrimitiveSizeInBits() <
3498 CI.getType()->getPrimitiveSizeInBits()&&
3499 A->getType()->getPrimitiveSizeInBits() ==
3500 CI.getType()->getPrimitiveSizeInBits()) {
3501 assert(CSrc->getType() != Type::ULongTy &&
3502 "Cannot have type bigger than ulong!");
3503 uint64_t AndValue = ~0ULL>>(64-CSrc->getType()->getPrimitiveSizeInBits());
3504 Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(),
3506 AndOp = ConstantExpr::getCast(AndOp, A->getType());
3507 Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
3508 if (And->getType() != CI.getType()) {
3509 And->setName(CSrc->getName()+".mask");
3510 InsertNewInstBefore(And, CI);
3511 And = new CastInst(And, CI.getType());
3517 // If this is a cast to bool, turn it into the appropriate setne instruction.
3518 if (CI.getType() == Type::BoolTy)
3519 return BinaryOperator::createSetNE(CI.getOperand(0),
3520 Constant::getNullValue(CI.getOperand(0)->getType()));
3522 // If casting the result of a getelementptr instruction with no offset, turn
3523 // this into a cast of the original pointer!
3525 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
3526 bool AllZeroOperands = true;
3527 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
3528 if (!isa<Constant>(GEP->getOperand(i)) ||
3529 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
3530 AllZeroOperands = false;
3533 if (AllZeroOperands) {
3534 CI.setOperand(0, GEP->getOperand(0));
3539 // If we are casting a malloc or alloca to a pointer to a type of the same
3540 // size, rewrite the allocation instruction to allocate the "right" type.
3542 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
3543 if (AI->hasOneUse() && !AI->isArrayAllocation())
3544 if (const PointerType *PTy = dyn_cast<PointerType>(CI.getType())) {
3545 // Get the type really allocated and the type casted to...
3546 const Type *AllocElTy = AI->getAllocatedType();
3547 const Type *CastElTy = PTy->getElementType();
3548 if (AllocElTy->isSized() && CastElTy->isSized()) {
3549 uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
3550 uint64_t CastElTySize = TD->getTypeSize(CastElTy);
3552 // If the allocation is for an even multiple of the cast type size
3553 if (CastElTySize && (AllocElTySize % CastElTySize == 0)) {
3554 Value *Amt = ConstantUInt::get(Type::UIntTy,
3555 AllocElTySize/CastElTySize);
3556 std::string Name = AI->getName(); AI->setName("");
3557 AllocationInst *New;
3558 if (isa<MallocInst>(AI))
3559 New = new MallocInst(CastElTy, Amt, Name);
3561 New = new AllocaInst(CastElTy, Amt, Name);
3562 InsertNewInstBefore(New, *AI);
3563 return ReplaceInstUsesWith(CI, New);
3568 if (SelectInst *SI = dyn_cast<SelectInst>(Src))
3569 if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
3571 if (isa<PHINode>(Src))
3572 if (Instruction *NV = FoldOpIntoPhi(CI))
3575 // If the source value is an instruction with only this use, we can attempt to
3576 // propagate the cast into the instruction. Also, only handle integral types
3578 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
3579 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
3580 CI.getType()->isInteger()) { // Don't mess with casts to bool here
3581 const Type *DestTy = CI.getType();
3582 unsigned SrcBitSize = Src->getType()->getPrimitiveSizeInBits();
3583 unsigned DestBitSize = DestTy->getPrimitiveSizeInBits();
3585 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
3586 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
3588 switch (SrcI->getOpcode()) {
3589 case Instruction::Add:
3590 case Instruction::Mul:
3591 case Instruction::And:
3592 case Instruction::Or:
3593 case Instruction::Xor:
3594 // If we are discarding information, or just changing the sign, rewrite.
3595 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
3596 // Don't insert two casts if they cannot be eliminated. We allow two
3597 // casts to be inserted if the sizes are the same. This could only be
3598 // converting signedness, which is a noop.
3599 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
3600 !ValueRequiresCast(Op0, DestTy, TD)) {
3601 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
3602 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
3603 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
3604 ->getOpcode(), Op0c, Op1c);
3608 // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
3609 if (SrcBitSize == 1 && SrcI->getOpcode() == Instruction::Xor &&
3610 Op1 == ConstantBool::True &&
3611 (!Op0->hasOneUse() || !isa<SetCondInst>(Op0))) {
3612 Value *New = InsertOperandCastBefore(Op0, DestTy, &CI);
3613 return BinaryOperator::createXor(New,
3614 ConstantInt::get(CI.getType(), 1));
3617 case Instruction::Shl:
3618 // Allow changing the sign of the source operand. Do not allow changing
3619 // the size of the shift, UNLESS the shift amount is a constant. We
3620 // mush not change variable sized shifts to a smaller size, because it
3621 // is undefined to shift more bits out than exist in the value.
3622 if (DestBitSize == SrcBitSize ||
3623 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
3624 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
3625 return new ShiftInst(Instruction::Shl, Op0c, Op1);
3628 case Instruction::Shr:
3629 // If this is a signed shr, and if all bits shifted in are about to be
3630 // truncated off, turn it into an unsigned shr to allow greater
3632 if (DestBitSize < SrcBitSize && Src->getType()->isSigned() &&
3633 isa<ConstantInt>(Op1)) {
3634 unsigned ShiftAmt = cast<ConstantUInt>(Op1)->getValue();
3635 if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
3636 // Convert to unsigned.
3637 Value *N1 = InsertOperandCastBefore(Op0,
3638 Op0->getType()->getUnsignedVersion(), &CI);
3639 // Insert the new shift, which is now unsigned.
3640 N1 = InsertNewInstBefore(new ShiftInst(Instruction::Shr, N1,
3641 Op1, Src->getName()), CI);
3642 return new CastInst(N1, CI.getType());
3647 case Instruction::SetNE:
3648 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
3649 if (Op1C->getRawValue() == 0) {
3650 // If the input only has the low bit set, simplify directly.
3652 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
3653 // cast (X != 0) to int --> X if X&~1 == 0
3654 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
3655 if (CI.getType() == Op0->getType())
3656 return ReplaceInstUsesWith(CI, Op0);
3658 return new CastInst(Op0, CI.getType());
3661 // If the input is an and with a single bit, shift then simplify.
3662 ConstantInt *AndRHS;
3663 if (match(Op0, m_And(m_Value(), m_ConstantInt(AndRHS))))
3664 if (AndRHS->getRawValue() &&
3665 (AndRHS->getRawValue() & (AndRHS->getRawValue()-1)) == 0) {
3666 unsigned ShiftAmt = Log2_64(AndRHS->getRawValue());
3667 // Perform an unsigned shr by shiftamt. Convert input to
3668 // unsigned if it is signed.
3670 if (In->getType()->isSigned())
3671 In = InsertNewInstBefore(new CastInst(In,
3672 In->getType()->getUnsignedVersion(), In->getName()),CI);
3673 // Insert the shift to put the result in the low bit.
3674 In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In,
3675 ConstantInt::get(Type::UByteTy, ShiftAmt),
3676 In->getName()+".lobit"), CI);
3677 if (CI.getType() == In->getType())
3678 return ReplaceInstUsesWith(CI, In);
3680 return new CastInst(In, CI.getType());
3685 case Instruction::SetEQ:
3686 // We if we are just checking for a seteq of a single bit and casting it
3687 // to an integer. If so, shift the bit to the appropriate place then
3688 // cast to integer to avoid the comparison.
3689 if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
3690 // Is Op1C a power of two or zero?
3691 if ((Op1C->getRawValue() & Op1C->getRawValue()-1) == 0) {
3692 // cast (X == 1) to int -> X iff X has only the low bit set.
3693 if (Op1C->getRawValue() == 1) {
3695 ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
3696 if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
3697 if (CI.getType() == Op0->getType())
3698 return ReplaceInstUsesWith(CI, Op0);
3700 return new CastInst(Op0, CI.getType());
3711 /// GetSelectFoldableOperands - We want to turn code that looks like this:
3713 /// %D = select %cond, %C, %A
3715 /// %C = select %cond, %B, 0
3718 /// Assuming that the specified instruction is an operand to the select, return
3719 /// a bitmask indicating which operands of this instruction are foldable if they
3720 /// equal the other incoming value of the select.
3722 static unsigned GetSelectFoldableOperands(Instruction *I) {
3723 switch (I->getOpcode()) {
3724 case Instruction::Add:
3725 case Instruction::Mul:
3726 case Instruction::And:
3727 case Instruction::Or:
3728 case Instruction::Xor:
3729 return 3; // Can fold through either operand.
3730 case Instruction::Sub: // Can only fold on the amount subtracted.
3731 case Instruction::Shl: // Can only fold on the shift amount.
3732 case Instruction::Shr:
3735 return 0; // Cannot fold
3739 /// GetSelectFoldableConstant - For the same transformation as the previous
3740 /// function, return the identity constant that goes into the select.
3741 static Constant *GetSelectFoldableConstant(Instruction *I) {
3742 switch (I->getOpcode()) {
3743 default: assert(0 && "This cannot happen!"); abort();
3744 case Instruction::Add:
3745 case Instruction::Sub:
3746 case Instruction::Or:
3747 case Instruction::Xor:
3748 return Constant::getNullValue(I->getType());
3749 case Instruction::Shl:
3750 case Instruction::Shr:
3751 return Constant::getNullValue(Type::UByteTy);
3752 case Instruction::And:
3753 return ConstantInt::getAllOnesValue(I->getType());
3754 case Instruction::Mul:
3755 return ConstantInt::get(I->getType(), 1);
3759 /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
3760 /// have the same opcode and only one use each. Try to simplify this.
3761 Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
3763 if (TI->getNumOperands() == 1) {
3764 // If this is a non-volatile load or a cast from the same type,
3766 if (TI->getOpcode() == Instruction::Cast) {
3767 if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
3770 return 0; // unknown unary op.
3773 // Fold this by inserting a select from the input values.
3774 SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
3775 FI->getOperand(0), SI.getName()+".v");
3776 InsertNewInstBefore(NewSI, SI);
3777 return new CastInst(NewSI, TI->getType());
3780 // Only handle binary operators here.
3781 if (!isa<ShiftInst>(TI) && !isa<BinaryOperator>(TI))
3784 // Figure out if the operations have any operands in common.
3785 Value *MatchOp, *OtherOpT, *OtherOpF;
3787 if (TI->getOperand(0) == FI->getOperand(0)) {
3788 MatchOp = TI->getOperand(0);
3789 OtherOpT = TI->getOperand(1);
3790 OtherOpF = FI->getOperand(1);
3791 MatchIsOpZero = true;
3792 } else if (TI->getOperand(1) == FI->getOperand(1)) {
3793 MatchOp = TI->getOperand(1);
3794 OtherOpT = TI->getOperand(0);
3795 OtherOpF = FI->getOperand(0);
3796 MatchIsOpZero = false;
3797 } else if (!TI->isCommutative()) {
3799 } else if (TI->getOperand(0) == FI->getOperand(1)) {
3800 MatchOp = TI->getOperand(0);
3801 OtherOpT = TI->getOperand(1);
3802 OtherOpF = FI->getOperand(0);
3803 MatchIsOpZero = true;
3804 } else if (TI->getOperand(1) == FI->getOperand(0)) {
3805 MatchOp = TI->getOperand(1);
3806 OtherOpT = TI->getOperand(0);
3807 OtherOpF = FI->getOperand(1);
3808 MatchIsOpZero = true;
3813 // If we reach here, they do have operations in common.
3814 SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
3815 OtherOpF, SI.getName()+".v");
3816 InsertNewInstBefore(NewSI, SI);
3818 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
3820 return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
3822 return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
3825 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI);
3827 return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp);
3831 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
3832 Value *CondVal = SI.getCondition();
3833 Value *TrueVal = SI.getTrueValue();
3834 Value *FalseVal = SI.getFalseValue();
3836 // select true, X, Y -> X
3837 // select false, X, Y -> Y
3838 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
3839 if (C == ConstantBool::True)
3840 return ReplaceInstUsesWith(SI, TrueVal);
3842 assert(C == ConstantBool::False);
3843 return ReplaceInstUsesWith(SI, FalseVal);
3846 // select C, X, X -> X
3847 if (TrueVal == FalseVal)
3848 return ReplaceInstUsesWith(SI, TrueVal);
3850 if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
3851 return ReplaceInstUsesWith(SI, FalseVal);
3852 if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
3853 return ReplaceInstUsesWith(SI, TrueVal);
3854 if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
3855 if (isa<Constant>(TrueVal))
3856 return ReplaceInstUsesWith(SI, TrueVal);
3858 return ReplaceInstUsesWith(SI, FalseVal);
3861 if (SI.getType() == Type::BoolTy)
3862 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
3863 if (C == ConstantBool::True) {
3864 // Change: A = select B, true, C --> A = or B, C
3865 return BinaryOperator::createOr(CondVal, FalseVal);
3867 // Change: A = select B, false, C --> A = and !B, C
3869 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
3870 "not."+CondVal->getName()), SI);
3871 return BinaryOperator::createAnd(NotCond, FalseVal);
3873 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
3874 if (C == ConstantBool::False) {
3875 // Change: A = select B, C, false --> A = and B, C
3876 return BinaryOperator::createAnd(CondVal, TrueVal);
3878 // Change: A = select B, C, true --> A = or !B, C
3880 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
3881 "not."+CondVal->getName()), SI);
3882 return BinaryOperator::createOr(NotCond, TrueVal);
3886 // Selecting between two integer constants?
3887 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
3888 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
3889 // select C, 1, 0 -> cast C to int
3890 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
3891 return new CastInst(CondVal, SI.getType());
3892 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
3893 // select C, 0, 1 -> cast !C to int
3895 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
3896 "not."+CondVal->getName()), SI);
3897 return new CastInst(NotCond, SI.getType());
3900 // If one of the constants is zero (we know they can't both be) and we
3901 // have a setcc instruction with zero, and we have an 'and' with the
3902 // non-constant value, eliminate this whole mess. This corresponds to
3903 // cases like this: ((X & 27) ? 27 : 0)
3904 if (TrueValC->isNullValue() || FalseValC->isNullValue())
3905 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
3906 if ((IC->getOpcode() == Instruction::SetEQ ||
3907 IC->getOpcode() == Instruction::SetNE) &&
3908 isa<ConstantInt>(IC->getOperand(1)) &&
3909 cast<Constant>(IC->getOperand(1))->isNullValue())
3910 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
3911 if (ICA->getOpcode() == Instruction::And &&
3912 isa<ConstantInt>(ICA->getOperand(1)) &&
3913 (ICA->getOperand(1) == TrueValC ||
3914 ICA->getOperand(1) == FalseValC) &&
3915 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
3916 // Okay, now we know that everything is set up, we just don't
3917 // know whether we have a setne or seteq and whether the true or
3918 // false val is the zero.
3919 bool ShouldNotVal = !TrueValC->isNullValue();
3920 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
3923 V = InsertNewInstBefore(BinaryOperator::create(
3924 Instruction::Xor, V, ICA->getOperand(1)), SI);
3925 return ReplaceInstUsesWith(SI, V);
3929 // See if we are selecting two values based on a comparison of the two values.
3930 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
3931 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
3932 // Transform (X == Y) ? X : Y -> Y
3933 if (SCI->getOpcode() == Instruction::SetEQ)
3934 return ReplaceInstUsesWith(SI, FalseVal);
3935 // Transform (X != Y) ? X : Y -> X
3936 if (SCI->getOpcode() == Instruction::SetNE)
3937 return ReplaceInstUsesWith(SI, TrueVal);
3938 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
3940 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
3941 // Transform (X == Y) ? Y : X -> X
3942 if (SCI->getOpcode() == Instruction::SetEQ)
3943 return ReplaceInstUsesWith(SI, FalseVal);
3944 // Transform (X != Y) ? Y : X -> Y
3945 if (SCI->getOpcode() == Instruction::SetNE)
3946 return ReplaceInstUsesWith(SI, TrueVal);
3947 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
3951 if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
3952 if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
3953 if (TI->hasOneUse() && FI->hasOneUse()) {
3954 bool isInverse = false;
3955 Instruction *AddOp = 0, *SubOp = 0;
3957 // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
3958 if (TI->getOpcode() == FI->getOpcode())
3959 if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
3962 // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
3963 // even legal for FP.
3964 if (TI->getOpcode() == Instruction::Sub &&
3965 FI->getOpcode() == Instruction::Add) {
3966 AddOp = FI; SubOp = TI;
3967 } else if (FI->getOpcode() == Instruction::Sub &&
3968 TI->getOpcode() == Instruction::Add) {
3969 AddOp = TI; SubOp = FI;
3973 Value *OtherAddOp = 0;
3974 if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
3975 OtherAddOp = AddOp->getOperand(1);
3976 } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
3977 OtherAddOp = AddOp->getOperand(0);
3981 // So at this point we know we have:
3982 // select C, (add X, Y), (sub X, ?)
3983 // We can do the transform profitably if either 'Y' = '?' or '?' is
3985 if (SubOp->getOperand(1) == AddOp ||
3986 isa<Constant>(SubOp->getOperand(1))) {
3988 if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
3989 NegVal = ConstantExpr::getNeg(C);
3991 NegVal = InsertNewInstBefore(
3992 BinaryOperator::createNeg(SubOp->getOperand(1)), SI);
3995 Value *NewTrueOp = OtherAddOp;
3996 Value *NewFalseOp = NegVal;
3998 std::swap(NewTrueOp, NewFalseOp);
3999 Instruction *NewSel =
4000 new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
4002 NewSel = InsertNewInstBefore(NewSel, SI);
4003 return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
4009 // See if we can fold the select into one of our operands.
4010 if (SI.getType()->isInteger()) {
4011 // See the comment above GetSelectFoldableOperands for a description of the
4012 // transformation we are doing here.
4013 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
4014 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
4015 !isa<Constant>(FalseVal))
4016 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
4017 unsigned OpToFold = 0;
4018 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
4020 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
4025 Constant *C = GetSelectFoldableConstant(TVI);
4026 std::string Name = TVI->getName(); TVI->setName("");
4027 Instruction *NewSel =
4028 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
4030 InsertNewInstBefore(NewSel, SI);
4031 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
4032 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
4033 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
4034 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
4036 assert(0 && "Unknown instruction!!");
4041 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
4042 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
4043 !isa<Constant>(TrueVal))
4044 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
4045 unsigned OpToFold = 0;
4046 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
4048 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
4053 Constant *C = GetSelectFoldableConstant(FVI);
4054 std::string Name = FVI->getName(); FVI->setName("");
4055 Instruction *NewSel =
4056 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
4058 InsertNewInstBefore(NewSel, SI);
4059 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
4060 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
4061 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
4062 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
4064 assert(0 && "Unknown instruction!!");
4070 if (BinaryOperator::isNot(CondVal)) {
4071 SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
4072 SI.setOperand(1, FalseVal);
4073 SI.setOperand(2, TrueVal);
4081 // CallInst simplification
4083 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
4084 // Intrinsics cannot occur in an invoke, so handle them here instead of in
4086 if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(&CI)) {
4087 bool Changed = false;
4089 // memmove/cpy/set of zero bytes is a noop.
4090 if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
4091 if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
4093 // FIXME: Increase alignment here.
4095 if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
4096 if (CI->getRawValue() == 1) {
4097 // Replace the instruction with just byte operations. We would
4098 // transform other cases to loads/stores, but we don't know if
4099 // alignment is sufficient.
4103 // If we have a memmove and the source operation is a constant global,
4104 // then the source and dest pointers can't alias, so we can change this
4105 // into a call to memcpy.
4106 if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI))
4107 if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
4108 if (GVSrc->isConstant()) {
4109 Module *M = CI.getParent()->getParent()->getParent();
4110 Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
4111 CI.getCalledFunction()->getFunctionType());
4112 CI.setOperand(0, MemCpy);
4116 if (Changed) return &CI;
4117 } else if (DbgStopPointInst *SPI = dyn_cast<DbgStopPointInst>(&CI)) {
4118 // If this stoppoint is at the same source location as the previous
4119 // stoppoint in the chain, it is not needed.
4120 if (DbgStopPointInst *PrevSPI =
4121 dyn_cast<DbgStopPointInst>(SPI->getChain()))
4122 if (SPI->getLineNo() == PrevSPI->getLineNo() &&
4123 SPI->getColNo() == PrevSPI->getColNo()) {
4124 SPI->replaceAllUsesWith(PrevSPI);
4125 return EraseInstFromFunction(CI);
4129 return visitCallSite(&CI);
4132 // InvokeInst simplification
4134 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
4135 return visitCallSite(&II);
4138 // visitCallSite - Improvements for call and invoke instructions.
4140 Instruction *InstCombiner::visitCallSite(CallSite CS) {
4141 bool Changed = false;
4143 // If the callee is a constexpr cast of a function, attempt to move the cast
4144 // to the arguments of the call/invoke.
4145 if (transformConstExprCastCall(CS)) return 0;
4147 Value *Callee = CS.getCalledValue();
4149 if (Function *CalleeF = dyn_cast<Function>(Callee))
4150 if (CalleeF->getCallingConv() != CS.getCallingConv()) {
4151 Instruction *OldCall = CS.getInstruction();
4152 // If the call and callee calling conventions don't match, this call must
4153 // be unreachable, as the call is undefined.
4154 new StoreInst(ConstantBool::True,
4155 UndefValue::get(PointerType::get(Type::BoolTy)), OldCall);
4156 if (!OldCall->use_empty())
4157 OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
4158 if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
4159 return EraseInstFromFunction(*OldCall);
4163 if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
4164 // This instruction is not reachable, just remove it. We insert a store to
4165 // undef so that we know that this code is not reachable, despite the fact
4166 // that we can't modify the CFG here.
4167 new StoreInst(ConstantBool::True,
4168 UndefValue::get(PointerType::get(Type::BoolTy)),
4169 CS.getInstruction());
4171 if (!CS.getInstruction()->use_empty())
4172 CS.getInstruction()->
4173 replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
4175 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
4176 // Don't break the CFG, insert a dummy cond branch.
4177 new BranchInst(II->getNormalDest(), II->getUnwindDest(),
4178 ConstantBool::True, II);
4180 return EraseInstFromFunction(*CS.getInstruction());
4183 const PointerType *PTy = cast<PointerType>(Callee->getType());
4184 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
4185 if (FTy->isVarArg()) {
4186 // See if we can optimize any arguments passed through the varargs area of
4188 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
4189 E = CS.arg_end(); I != E; ++I)
4190 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
4191 // If this cast does not effect the value passed through the varargs
4192 // area, we can eliminate the use of the cast.
4193 Value *Op = CI->getOperand(0);
4194 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
4201 return Changed ? CS.getInstruction() : 0;
4204 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
4205 // attempt to move the cast to the arguments of the call/invoke.
4207 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
4208 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
4209 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
4210 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
4212 Function *Callee = cast<Function>(CE->getOperand(0));
4213 Instruction *Caller = CS.getInstruction();
4215 // Okay, this is a cast from a function to a different type. Unless doing so
4216 // would cause a type conversion of one of our arguments, change this call to
4217 // be a direct call with arguments casted to the appropriate types.
4219 const FunctionType *FT = Callee->getFunctionType();
4220 const Type *OldRetTy = Caller->getType();
4222 // Check to see if we are changing the return type...
4223 if (OldRetTy != FT->getReturnType()) {
4224 if (Callee->isExternal() &&
4225 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
4226 !Caller->use_empty())
4227 return false; // Cannot transform this return value...
4229 // If the callsite is an invoke instruction, and the return value is used by
4230 // a PHI node in a successor, we cannot change the return type of the call
4231 // because there is no place to put the cast instruction (without breaking
4232 // the critical edge). Bail out in this case.
4233 if (!Caller->use_empty())
4234 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
4235 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
4237 if (PHINode *PN = dyn_cast<PHINode>(*UI))
4238 if (PN->getParent() == II->getNormalDest() ||
4239 PN->getParent() == II->getUnwindDest())
4243 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
4244 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
4246 CallSite::arg_iterator AI = CS.arg_begin();
4247 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
4248 const Type *ParamTy = FT->getParamType(i);
4249 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
4250 if (Callee->isExternal() && !isConvertible) return false;
4253 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
4254 Callee->isExternal())
4255 return false; // Do not delete arguments unless we have a function body...
4257 // Okay, we decided that this is a safe thing to do: go ahead and start
4258 // inserting cast instructions as necessary...
4259 std::vector<Value*> Args;
4260 Args.reserve(NumActualArgs);
4262 AI = CS.arg_begin();
4263 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
4264 const Type *ParamTy = FT->getParamType(i);
4265 if ((*AI)->getType() == ParamTy) {
4266 Args.push_back(*AI);
4268 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
4273 // If the function takes more arguments than the call was taking, add them
4275 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
4276 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
4278 // If we are removing arguments to the function, emit an obnoxious warning...
4279 if (FT->getNumParams() < NumActualArgs)
4280 if (!FT->isVarArg()) {
4281 std::cerr << "WARNING: While resolving call to function '"
4282 << Callee->getName() << "' arguments were dropped!\n";
4284 // Add all of the arguments in their promoted form to the arg list...
4285 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
4286 const Type *PTy = getPromotedType((*AI)->getType());
4287 if (PTy != (*AI)->getType()) {
4288 // Must promote to pass through va_arg area!
4289 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
4290 InsertNewInstBefore(Cast, *Caller);
4291 Args.push_back(Cast);
4293 Args.push_back(*AI);
4298 if (FT->getReturnType() == Type::VoidTy)
4299 Caller->setName(""); // Void type should not have a name...
4302 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4303 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
4304 Args, Caller->getName(), Caller);
4305 cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
4307 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
4308 if (cast<CallInst>(Caller)->isTailCall())
4309 cast<CallInst>(NC)->setTailCall();
4310 cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
4313 // Insert a cast of the return type as necessary...
4315 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
4316 if (NV->getType() != Type::VoidTy) {
4317 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
4319 // If this is an invoke instruction, we should insert it after the first
4320 // non-phi, instruction in the normal successor block.
4321 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
4322 BasicBlock::iterator I = II->getNormalDest()->begin();
4323 while (isa<PHINode>(I)) ++I;
4324 InsertNewInstBefore(NC, *I);
4326 // Otherwise, it's a call, just insert cast right after the call instr
4327 InsertNewInstBefore(NC, *Caller);
4329 AddUsersToWorkList(*Caller);
4331 NV = UndefValue::get(Caller->getType());
4335 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
4336 Caller->replaceAllUsesWith(NV);
4337 Caller->getParent()->getInstList().erase(Caller);
4338 removeFromWorkList(Caller);
4343 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
4344 // operator and they all are only used by the PHI, PHI together their
4345 // inputs, and do the operation once, to the result of the PHI.
4346 Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
4347 Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
4349 // Scan the instruction, looking for input operations that can be folded away.
4350 // If all input operands to the phi are the same instruction (e.g. a cast from
4351 // the same type or "+42") we can pull the operation through the PHI, reducing
4352 // code size and simplifying code.
4353 Constant *ConstantOp = 0;
4354 const Type *CastSrcTy = 0;
4355 if (isa<CastInst>(FirstInst)) {
4356 CastSrcTy = FirstInst->getOperand(0)->getType();
4357 } else if (isa<BinaryOperator>(FirstInst) || isa<ShiftInst>(FirstInst)) {
4358 // Can fold binop or shift if the RHS is a constant.
4359 ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
4360 if (ConstantOp == 0) return 0;
4362 return 0; // Cannot fold this operation.
4365 // Check to see if all arguments are the same operation.
4366 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4367 if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
4368 Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
4369 if (!I->hasOneUse() || I->getOpcode() != FirstInst->getOpcode())
4372 if (I->getOperand(0)->getType() != CastSrcTy)
4373 return 0; // Cast operation must match.
4374 } else if (I->getOperand(1) != ConstantOp) {
4379 // Okay, they are all the same operation. Create a new PHI node of the
4380 // correct type, and PHI together all of the LHS's of the instructions.
4381 PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
4382 PN.getName()+".in");
4383 NewPN->reserveOperandSpace(PN.getNumOperands()/2);
4385 Value *InVal = FirstInst->getOperand(0);
4386 NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
4388 // Add all operands to the new PHI.
4389 for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
4390 Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
4391 if (NewInVal != InVal)
4393 NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
4398 // The new PHI unions all of the same values together. This is really
4399 // common, so we handle it intelligently here for compile-time speed.
4403 InsertNewInstBefore(NewPN, PN);
4407 // Insert and return the new operation.
4408 if (isa<CastInst>(FirstInst))
4409 return new CastInst(PhiVal, PN.getType());
4410 else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
4411 return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
4413 return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(),
4414 PhiVal, ConstantOp);
4417 /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
4419 static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &PotentiallyDeadPHIs) {
4420 if (PN->use_empty()) return true;
4421 if (!PN->hasOneUse()) return false;
4423 // Remember this node, and if we find the cycle, return.
4424 if (!PotentiallyDeadPHIs.insert(PN).second)
4427 if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
4428 return DeadPHICycle(PU, PotentiallyDeadPHIs);
4433 // PHINode simplification
4435 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
4436 if (Value *V = PN.hasConstantValue())
4437 return ReplaceInstUsesWith(PN, V);
4439 // If the only user of this instruction is a cast instruction, and all of the
4440 // incoming values are constants, change this PHI to merge together the casted
4443 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
4444 if (CI->getType() != PN.getType()) { // noop casts will be folded
4445 bool AllConstant = true;
4446 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
4447 if (!isa<Constant>(PN.getIncomingValue(i))) {
4448 AllConstant = false;
4452 // Make a new PHI with all casted values.
4453 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
4454 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
4455 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
4456 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
4457 PN.getIncomingBlock(i));
4460 // Update the cast instruction.
4461 CI->setOperand(0, New);
4462 WorkList.push_back(CI); // revisit the cast instruction to fold.
4463 WorkList.push_back(New); // Make sure to revisit the new Phi
4464 return &PN; // PN is now dead!
4468 // If all PHI operands are the same operation, pull them through the PHI,
4469 // reducing code size.
4470 if (isa<Instruction>(PN.getIncomingValue(0)) &&
4471 PN.getIncomingValue(0)->hasOneUse())
4472 if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
4475 // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
4476 // this PHI only has a single use (a PHI), and if that PHI only has one use (a
4477 // PHI)... break the cycle.
4479 if (PHINode *PU = dyn_cast<PHINode>(PN.use_back())) {
4480 std::set<PHINode*> PotentiallyDeadPHIs;
4481 PotentiallyDeadPHIs.insert(&PN);
4482 if (DeadPHICycle(PU, PotentiallyDeadPHIs))
4483 return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
4489 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
4490 Instruction *InsertPoint,
4492 unsigned PS = IC->getTargetData().getPointerSize();
4493 const Type *VTy = V->getType();
4494 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
4495 // We must insert a cast to ensure we sign-extend.
4496 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
4497 V->getName()), *InsertPoint);
4498 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
4503 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
4504 Value *PtrOp = GEP.getOperand(0);
4505 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
4506 // If so, eliminate the noop.
4507 if (GEP.getNumOperands() == 1)
4508 return ReplaceInstUsesWith(GEP, PtrOp);
4510 if (isa<UndefValue>(GEP.getOperand(0)))
4511 return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
4513 bool HasZeroPointerIndex = false;
4514 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
4515 HasZeroPointerIndex = C->isNullValue();
4517 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
4518 return ReplaceInstUsesWith(GEP, PtrOp);
4520 // Eliminate unneeded casts for indices.
4521 bool MadeChange = false;
4522 gep_type_iterator GTI = gep_type_begin(GEP);
4523 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
4524 if (isa<SequentialType>(*GTI)) {
4525 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
4526 Value *Src = CI->getOperand(0);
4527 const Type *SrcTy = Src->getType();
4528 const Type *DestTy = CI->getType();
4529 if (Src->getType()->isInteger()) {
4530 if (SrcTy->getPrimitiveSizeInBits() ==
4531 DestTy->getPrimitiveSizeInBits()) {
4532 // We can always eliminate a cast from ulong or long to the other.
4533 // We can always eliminate a cast from uint to int or the other on
4534 // 32-bit pointer platforms.
4535 if (DestTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()){
4537 GEP.setOperand(i, Src);
4539 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
4540 SrcTy->getPrimitiveSize() == 4) {
4541 // We can always eliminate a cast from int to [u]long. We can
4542 // eliminate a cast from uint to [u]long iff the target is a 32-bit
4544 if (SrcTy->isSigned() ||
4545 SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
4547 GEP.setOperand(i, Src);
4552 // If we are using a wider index than needed for this platform, shrink it
4553 // to what we need. If the incoming value needs a cast instruction,
4554 // insert it. This explicit cast can make subsequent optimizations more
4556 Value *Op = GEP.getOperand(i);
4557 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
4558 if (Constant *C = dyn_cast<Constant>(Op)) {
4559 GEP.setOperand(i, ConstantExpr::getCast(C,
4560 TD->getIntPtrType()->getSignedVersion()));
4563 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
4564 Op->getName()), GEP);
4565 GEP.setOperand(i, Op);
4569 // If this is a constant idx, make sure to canonicalize it to be a signed
4570 // operand, otherwise CSE and other optimizations are pessimized.
4571 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
4572 GEP.setOperand(i, ConstantExpr::getCast(CUI,
4573 CUI->getType()->getSignedVersion()));
4577 if (MadeChange) return &GEP;
4579 // Combine Indices - If the source pointer to this getelementptr instruction
4580 // is a getelementptr instruction, combine the indices of the two
4581 // getelementptr instructions into a single instruction.
4583 std::vector<Value*> SrcGEPOperands;
4584 if (User *Src = dyn_castGetElementPtr(PtrOp))
4585 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
4587 if (!SrcGEPOperands.empty()) {
4588 // Note that if our source is a gep chain itself that we wait for that
4589 // chain to be resolved before we perform this transformation. This
4590 // avoids us creating a TON of code in some cases.
4592 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
4593 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
4594 return 0; // Wait until our source is folded to completion.
4596 std::vector<Value *> Indices;
4598 // Find out whether the last index in the source GEP is a sequential idx.
4599 bool EndsWithSequential = false;
4600 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
4601 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
4602 EndsWithSequential = !isa<StructType>(*I);
4604 // Can we combine the two pointer arithmetics offsets?
4605 if (EndsWithSequential) {
4606 // Replace: gep (gep %P, long B), long A, ...
4607 // With: T = long A+B; gep %P, T, ...
4609 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
4610 if (SO1 == Constant::getNullValue(SO1->getType())) {
4612 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
4615 // If they aren't the same type, convert both to an integer of the
4616 // target's pointer size.
4617 if (SO1->getType() != GO1->getType()) {
4618 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
4619 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
4620 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
4621 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
4623 unsigned PS = TD->getPointerSize();
4624 if (SO1->getType()->getPrimitiveSize() == PS) {
4625 // Convert GO1 to SO1's type.
4626 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
4628 } else if (GO1->getType()->getPrimitiveSize() == PS) {
4629 // Convert SO1 to GO1's type.
4630 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
4632 const Type *PT = TD->getIntPtrType();
4633 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
4634 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
4638 if (isa<Constant>(SO1) && isa<Constant>(GO1))
4639 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
4641 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
4642 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
4646 // Recycle the GEP we already have if possible.
4647 if (SrcGEPOperands.size() == 2) {
4648 GEP.setOperand(0, SrcGEPOperands[0]);
4649 GEP.setOperand(1, Sum);
4652 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
4653 SrcGEPOperands.end()-1);
4654 Indices.push_back(Sum);
4655 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
4657 } else if (isa<Constant>(*GEP.idx_begin()) &&
4658 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
4659 SrcGEPOperands.size() != 1) {
4660 // Otherwise we can do the fold if the first index of the GEP is a zero
4661 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
4662 SrcGEPOperands.end());
4663 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
4666 if (!Indices.empty())
4667 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
4669 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
4670 // GEP of global variable. If all of the indices for this GEP are
4671 // constants, we can promote this to a constexpr instead of an instruction.
4673 // Scan for nonconstants...
4674 std::vector<Constant*> Indices;
4675 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
4676 for (; I != E && isa<Constant>(*I); ++I)
4677 Indices.push_back(cast<Constant>(*I));
4679 if (I == E) { // If they are all constants...
4680 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
4682 // Replace all uses of the GEP with the new constexpr...
4683 return ReplaceInstUsesWith(GEP, CE);
4685 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(PtrOp)) {
4686 if (CE->getOpcode() == Instruction::Cast) {
4687 if (HasZeroPointerIndex) {
4688 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
4689 // into : GEP [10 x ubyte]* X, long 0, ...
4691 // This occurs when the program declares an array extern like "int X[];"
4693 Constant *X = CE->getOperand(0);
4694 const PointerType *CPTy = cast<PointerType>(CE->getType());
4695 if (const PointerType *XTy = dyn_cast<PointerType>(X->getType()))
4696 if (const ArrayType *XATy =
4697 dyn_cast<ArrayType>(XTy->getElementType()))
4698 if (const ArrayType *CATy =
4699 dyn_cast<ArrayType>(CPTy->getElementType()))
4700 if (CATy->getElementType() == XATy->getElementType()) {
4701 // At this point, we know that the cast source type is a pointer
4702 // to an array of the same type as the destination pointer
4703 // array. Because the array type is never stepped over (there
4704 // is a leading zero) we can fold the cast into this GEP.
4705 GEP.setOperand(0, X);
4708 } else if (GEP.getNumOperands() == 2 &&
4709 isa<PointerType>(CE->getOperand(0)->getType())) {
4710 // Transform things like:
4711 // %t = getelementptr ubyte* cast ([2 x sbyte]* %str to ubyte*), uint %V
4712 // into: %t1 = getelementptr [2 x sbyte*]* %str, int 0, uint %V; cast
4713 Constant *X = CE->getOperand(0);
4714 const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
4715 const Type *ResElTy =cast<PointerType>(CE->getType())->getElementType();
4716 if (isa<ArrayType>(SrcElTy) &&
4717 TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
4718 TD->getTypeSize(ResElTy)) {
4719 Value *V = InsertNewInstBefore(
4720 new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
4721 GEP.getOperand(1), GEP.getName()), GEP);
4722 return new CastInst(V, GEP.getType());
4731 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
4732 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
4733 if (AI.isArrayAllocation()) // Check C != 1
4734 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
4735 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
4736 AllocationInst *New = 0;
4738 // Create and insert the replacement instruction...
4739 if (isa<MallocInst>(AI))
4740 New = new MallocInst(NewTy, 0, AI.getName());
4742 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
4743 New = new AllocaInst(NewTy, 0, AI.getName());
4746 InsertNewInstBefore(New, AI);
4748 // Scan to the end of the allocation instructions, to skip over a block of
4749 // allocas if possible...
4751 BasicBlock::iterator It = New;
4752 while (isa<AllocationInst>(*It)) ++It;
4754 // Now that I is pointing to the first non-allocation-inst in the block,
4755 // insert our getelementptr instruction...
4757 Value *NullIdx = Constant::getNullValue(Type::IntTy);
4758 Value *V = new GetElementPtrInst(New, NullIdx, NullIdx,
4759 New->getName()+".sub", It);
4761 // Now make everything use the getelementptr instead of the original
4763 return ReplaceInstUsesWith(AI, V);
4764 } else if (isa<UndefValue>(AI.getArraySize())) {
4765 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
4768 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
4769 // Note that we only do this for alloca's, because malloc should allocate and
4770 // return a unique pointer, even for a zero byte allocation.
4771 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
4772 TD->getTypeSize(AI.getAllocatedType()) == 0)
4773 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
4778 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
4779 Value *Op = FI.getOperand(0);
4781 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
4782 if (CastInst *CI = dyn_cast<CastInst>(Op))
4783 if (isa<PointerType>(CI->getOperand(0)->getType())) {
4784 FI.setOperand(0, CI->getOperand(0));
4788 // free undef -> unreachable.
4789 if (isa<UndefValue>(Op)) {
4790 // Insert a new store to null because we cannot modify the CFG here.
4791 new StoreInst(ConstantBool::True,
4792 UndefValue::get(PointerType::get(Type::BoolTy)), &FI);
4793 return EraseInstFromFunction(FI);
4796 // If we have 'free null' delete the instruction. This can happen in stl code
4797 // when lots of inlining happens.
4798 if (isa<ConstantPointerNull>(Op))
4799 return EraseInstFromFunction(FI);
4805 /// GetGEPGlobalInitializer - Given a constant, and a getelementptr
4806 /// constantexpr, return the constant value being addressed by the constant
4807 /// expression, or null if something is funny.
4809 static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
4810 if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
4811 return 0; // Do not allow stepping over the value!
4813 // Loop over all of the operands, tracking down which value we are
4815 gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
4816 for (++I; I != E; ++I)
4817 if (const StructType *STy = dyn_cast<StructType>(*I)) {
4818 ConstantUInt *CU = cast<ConstantUInt>(I.getOperand());
4819 assert(CU->getValue() < STy->getNumElements() &&
4820 "Struct index out of range!");
4821 unsigned El = (unsigned)CU->getValue();
4822 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
4823 C = CS->getOperand(El);
4824 } else if (isa<ConstantAggregateZero>(C)) {
4825 C = Constant::getNullValue(STy->getElementType(El));
4826 } else if (isa<UndefValue>(C)) {
4827 C = UndefValue::get(STy->getElementType(El));
4831 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
4832 const ArrayType *ATy = cast<ArrayType>(*I);
4833 if ((uint64_t)CI->getRawValue() >= ATy->getNumElements()) return 0;
4834 if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
4835 C = CA->getOperand((unsigned)CI->getRawValue());
4836 else if (isa<ConstantAggregateZero>(C))
4837 C = Constant::getNullValue(ATy->getElementType());
4838 else if (isa<UndefValue>(C))
4839 C = UndefValue::get(ATy->getElementType());
4848 /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
4849 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
4850 User *CI = cast<User>(LI.getOperand(0));
4851 Value *CastOp = CI->getOperand(0);
4853 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
4854 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
4855 const Type *SrcPTy = SrcTy->getElementType();
4857 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
4858 // If the source is an array, the code below will not succeed. Check to
4859 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
4861 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
4862 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
4863 if (ASrcTy->getNumElements() != 0) {
4864 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
4865 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
4866 SrcTy = cast<PointerType>(CastOp->getType());
4867 SrcPTy = SrcTy->getElementType();
4870 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
4871 // Do not allow turning this into a load of an integer, which is then
4872 // casted to a pointer, this pessimizes pointer analysis a lot.
4873 (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
4874 IC.getTargetData().getTypeSize(SrcPTy) ==
4875 IC.getTargetData().getTypeSize(DestPTy)) {
4877 // Okay, we are casting from one integer or pointer type to another of
4878 // the same size. Instead of casting the pointer before the load, cast
4879 // the result of the loaded value.
4880 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
4882 LI.isVolatile()),LI);
4883 // Now cast the result of the load.
4884 return new CastInst(NewLoad, LI.getType());
4891 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
4892 /// from this value cannot trap. If it is not obviously safe to load from the
4893 /// specified pointer, we do a quick local scan of the basic block containing
4894 /// ScanFrom, to determine if the address is already accessed.
4895 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
4896 // If it is an alloca or global variable, it is always safe to load from.
4897 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
4899 // Otherwise, be a little bit agressive by scanning the local block where we
4900 // want to check to see if the pointer is already being loaded or stored
4901 // from/to. If so, the previous load or store would have already trapped,
4902 // so there is no harm doing an extra load (also, CSE will later eliminate
4903 // the load entirely).
4904 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
4909 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
4910 if (LI->getOperand(0) == V) return true;
4911 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
4912 if (SI->getOperand(1) == V) return true;
4918 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
4919 Value *Op = LI.getOperand(0);
4921 // load (cast X) --> cast (load X) iff safe
4922 if (CastInst *CI = dyn_cast<CastInst>(Op))
4923 if (Instruction *Res = InstCombineLoadCast(*this, LI))
4926 // None of the following transforms are legal for volatile loads.
4927 if (LI.isVolatile()) return 0;
4929 if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
4930 if (isa<ConstantPointerNull>(GEPI->getOperand(0)) ||
4931 isa<UndefValue>(GEPI->getOperand(0))) {
4932 // Insert a new store to null instruction before the load to indicate
4933 // that this code is not reachable. We do this instead of inserting
4934 // an unreachable instruction directly because we cannot modify the
4936 new StoreInst(UndefValue::get(LI.getType()),
4937 Constant::getNullValue(Op->getType()), &LI);
4938 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
4941 if (Constant *C = dyn_cast<Constant>(Op)) {
4942 // load null/undef -> undef
4943 if ((C->isNullValue() || isa<UndefValue>(C))) {
4944 // Insert a new store to null instruction before the load to indicate that
4945 // this code is not reachable. We do this instead of inserting an
4946 // unreachable instruction directly because we cannot modify the CFG.
4947 new StoreInst(UndefValue::get(LI.getType()),
4948 Constant::getNullValue(Op->getType()), &LI);
4949 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
4952 // Instcombine load (constant global) into the value loaded.
4953 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
4954 if (GV->isConstant() && !GV->isExternal())
4955 return ReplaceInstUsesWith(LI, GV->getInitializer());
4957 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
4958 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
4959 if (CE->getOpcode() == Instruction::GetElementPtr) {
4960 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
4961 if (GV->isConstant() && !GV->isExternal())
4962 if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
4963 return ReplaceInstUsesWith(LI, V);
4964 if (CE->getOperand(0)->isNullValue()) {
4965 // Insert a new store to null instruction before the load to indicate
4966 // that this code is not reachable. We do this instead of inserting
4967 // an unreachable instruction directly because we cannot modify the
4969 new StoreInst(UndefValue::get(LI.getType()),
4970 Constant::getNullValue(Op->getType()), &LI);
4971 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
4974 } else if (CE->getOpcode() == Instruction::Cast) {
4975 if (Instruction *Res = InstCombineLoadCast(*this, LI))
4980 if (Op->hasOneUse()) {
4981 // Change select and PHI nodes to select values instead of addresses: this
4982 // helps alias analysis out a lot, allows many others simplifications, and
4983 // exposes redundancy in the code.
4985 // Note that we cannot do the transformation unless we know that the
4986 // introduced loads cannot trap! Something like this is valid as long as
4987 // the condition is always false: load (select bool %C, int* null, int* %G),
4988 // but it would not be valid if we transformed it to load from null
4991 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
4992 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
4993 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
4994 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
4995 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
4996 SI->getOperand(1)->getName()+".val"), LI);
4997 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
4998 SI->getOperand(2)->getName()+".val"), LI);
4999 return new SelectInst(SI->getCondition(), V1, V2);
5002 // load (select (cond, null, P)) -> load P
5003 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
5004 if (C->isNullValue()) {
5005 LI.setOperand(0, SI->getOperand(2));
5009 // load (select (cond, P, null)) -> load P
5010 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
5011 if (C->isNullValue()) {
5012 LI.setOperand(0, SI->getOperand(1));
5016 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
5017 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
5018 bool Safe = PN->getParent() == LI.getParent();
5020 // Scan all of the instructions between the PHI and the load to make
5021 // sure there are no instructions that might possibly alter the value
5022 // loaded from the PHI.
5024 BasicBlock::iterator I = &LI;
5025 for (--I; !isa<PHINode>(I); --I)
5026 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
5032 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
5033 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
5034 PN->getIncomingBlock(i)->getTerminator()))
5039 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
5040 InsertNewInstBefore(NewPN, *PN);
5041 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
5043 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
5044 BasicBlock *BB = PN->getIncomingBlock(i);
5045 Value *&TheLoad = LoadMap[BB];
5047 Value *InVal = PN->getIncomingValue(i);
5048 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
5049 InVal->getName()+".val"),
5050 *BB->getTerminator());
5052 NewPN->addIncoming(TheLoad, BB);
5054 return ReplaceInstUsesWith(LI, NewPN);
5061 /// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store (cast V), P'
5063 static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
5064 User *CI = cast<User>(SI.getOperand(1));
5065 Value *CastOp = CI->getOperand(0);
5067 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
5068 if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
5069 const Type *SrcPTy = SrcTy->getElementType();
5071 if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
5072 // If the source is an array, the code below will not succeed. Check to
5073 // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
5075 if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
5076 if (Constant *CSrc = dyn_cast<Constant>(CastOp))
5077 if (ASrcTy->getNumElements() != 0) {
5078 std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
5079 CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
5080 SrcTy = cast<PointerType>(CastOp->getType());
5081 SrcPTy = SrcTy->getElementType();
5084 if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
5085 IC.getTargetData().getTypeSize(SrcPTy) ==
5086 IC.getTargetData().getTypeSize(DestPTy)) {
5088 // Okay, we are casting from one integer or pointer type to another of
5089 // the same size. Instead of casting the pointer before the store, cast
5090 // the value to be stored.
5092 if (Constant *C = dyn_cast<Constant>(SI.getOperand(0)))
5093 NewCast = ConstantExpr::getCast(C, SrcPTy);
5095 NewCast = IC.InsertNewInstBefore(new CastInst(SI.getOperand(0),
5097 SI.getOperand(0)->getName()+".c"), SI);
5099 return new StoreInst(NewCast, CastOp);
5106 Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
5107 Value *Val = SI.getOperand(0);
5108 Value *Ptr = SI.getOperand(1);
5110 if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
5111 removeFromWorkList(&SI);
5112 SI.eraseFromParent();
5117 if (SI.isVolatile()) return 0; // Don't hack volatile loads.
5119 // store X, null -> turns into 'unreachable' in SimplifyCFG
5120 if (isa<ConstantPointerNull>(Ptr)) {
5121 if (!isa<UndefValue>(Val)) {
5122 SI.setOperand(0, UndefValue::get(Val->getType()));
5123 if (Instruction *U = dyn_cast<Instruction>(Val))
5124 WorkList.push_back(U); // Dropped a use.
5127 return 0; // Do not modify these!
5130 // store undef, Ptr -> noop
5131 if (isa<UndefValue>(Val)) {
5132 removeFromWorkList(&SI);
5133 SI.eraseFromParent();
5138 // If the pointer destination is a cast, see if we can fold the cast into the
5140 if (CastInst *CI = dyn_cast<CastInst>(Ptr))
5141 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5143 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
5144 if (CE->getOpcode() == Instruction::Cast)
5145 if (Instruction *Res = InstCombineStoreToCast(*this, SI))
5152 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
5153 // Change br (not X), label True, label False to: br X, label False, True
5155 BasicBlock *TrueDest;
5156 BasicBlock *FalseDest;
5157 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
5158 !isa<Constant>(X)) {
5159 // Swap Destinations and condition...
5161 BI.setSuccessor(0, FalseDest);
5162 BI.setSuccessor(1, TrueDest);
5166 // Cannonicalize setne -> seteq
5167 Instruction::BinaryOps Op; Value *Y;
5168 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
5169 TrueDest, FalseDest)))
5170 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
5171 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
5172 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
5173 std::string Name = I->getName(); I->setName("");
5174 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
5175 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
5176 // Swap Destinations and condition...
5177 BI.setCondition(NewSCC);
5178 BI.setSuccessor(0, FalseDest);
5179 BI.setSuccessor(1, TrueDest);
5180 removeFromWorkList(I);
5181 I->getParent()->getInstList().erase(I);
5182 WorkList.push_back(cast<Instruction>(NewSCC));
5189 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
5190 Value *Cond = SI.getCondition();
5191 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
5192 if (I->getOpcode() == Instruction::Add)
5193 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
5194 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
5195 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
5196 SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
5198 SI.setOperand(0, I->getOperand(0));
5199 WorkList.push_back(I);
5207 void InstCombiner::removeFromWorkList(Instruction *I) {
5208 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
5213 /// TryToSinkInstruction - Try to move the specified instruction from its
5214 /// current block into the beginning of DestBlock, which can only happen if it's
5215 /// safe to move the instruction past all of the instructions between it and the
5216 /// end of its block.
5217 static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
5218 assert(I->hasOneUse() && "Invariants didn't hold!");
5220 // Cannot move control-flow-involving instructions.
5221 if (isa<PHINode>(I) || isa<InvokeInst>(I) || isa<CallInst>(I)) return false;
5223 // Do not sink alloca instructions out of the entry block.
5224 if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front())
5227 // We can only sink load instructions if there is nothing between the load and
5228 // the end of block that could change the value.
5229 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
5230 if (LI->isVolatile()) return false; // Don't sink volatile loads.
5232 for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
5234 if (Scan->mayWriteToMemory())
5238 BasicBlock::iterator InsertPos = DestBlock->begin();
5239 while (isa<PHINode>(InsertPos)) ++InsertPos;
5241 BasicBlock *SrcBlock = I->getParent();
5242 DestBlock->getInstList().splice(InsertPos, SrcBlock->getInstList(), I);
5247 bool InstCombiner::runOnFunction(Function &F) {
5248 bool Changed = false;
5249 TD = &getAnalysis<TargetData>();
5252 // Populate the worklist with the reachable instructions.
5253 std::set<BasicBlock*> Visited;
5254 for (df_ext_iterator<BasicBlock*> BB = df_ext_begin(&F.front(), Visited),
5255 E = df_ext_end(&F.front(), Visited); BB != E; ++BB)
5256 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
5257 WorkList.push_back(I);
5259 // Do a quick scan over the function. If we find any blocks that are
5260 // unreachable, remove any instructions inside of them. This prevents
5261 // the instcombine code from having to deal with some bad special cases.
5262 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
5263 if (!Visited.count(BB)) {
5264 Instruction *Term = BB->getTerminator();
5265 while (Term != BB->begin()) { // Remove instrs bottom-up
5266 BasicBlock::iterator I = Term; --I;
5268 DEBUG(std::cerr << "IC: DCE: " << *I);
5271 if (!I->use_empty())
5272 I->replaceAllUsesWith(UndefValue::get(I->getType()));
5273 I->eraseFromParent();
5278 while (!WorkList.empty()) {
5279 Instruction *I = WorkList.back(); // Get an instruction from the worklist
5280 WorkList.pop_back();
5282 // Check to see if we can DCE or ConstantPropagate the instruction...
5283 // Check to see if we can DIE the instruction...
5284 if (isInstructionTriviallyDead(I)) {
5285 // Add operands to the worklist...
5286 if (I->getNumOperands() < 4)
5287 AddUsesToWorkList(*I);
5290 DEBUG(std::cerr << "IC: DCE: " << *I);
5292 I->eraseFromParent();
5293 removeFromWorkList(I);
5297 // Instruction isn't dead, see if we can constant propagate it...
5298 if (Constant *C = ConstantFoldInstruction(I)) {
5299 Value* Ptr = I->getOperand(0);
5300 if (isa<GetElementPtrInst>(I) &&
5301 cast<Constant>(Ptr)->isNullValue() &&
5302 !isa<ConstantPointerNull>(C) &&
5303 cast<PointerType>(Ptr->getType())->getElementType()->isSized()) {
5304 // If this is a constant expr gep that is effectively computing an
5305 // "offsetof", fold it into 'cast int X to T*' instead of 'gep 0, 0, 12'
5306 bool isFoldableGEP = true;
5307 for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
5308 if (!isa<ConstantInt>(I->getOperand(i)))
5309 isFoldableGEP = false;
5310 if (isFoldableGEP) {
5311 uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
5312 std::vector<Value*>(I->op_begin()+1, I->op_end()));
5313 C = ConstantUInt::get(Type::ULongTy, Offset);
5314 C = ConstantExpr::getCast(C, TD->getIntPtrType());
5315 C = ConstantExpr::getCast(C, I->getType());
5319 DEBUG(std::cerr << "IC: ConstFold to: " << *C << " from: " << *I);
5321 // Add operands to the worklist...
5322 AddUsesToWorkList(*I);
5323 ReplaceInstUsesWith(*I, C);
5326 I->getParent()->getInstList().erase(I);
5327 removeFromWorkList(I);
5331 // See if we can trivially sink this instruction to a successor basic block.
5332 if (I->hasOneUse()) {
5333 BasicBlock *BB = I->getParent();
5334 BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
5335 if (UserParent != BB) {
5336 bool UserIsSuccessor = false;
5337 // See if the user is one of our successors.
5338 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
5339 if (*SI == UserParent) {
5340 UserIsSuccessor = true;
5344 // If the user is one of our immediate successors, and if that successor
5345 // only has us as a predecessors (we'd have to split the critical edge
5346 // otherwise), we can keep going.
5347 if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
5348 next(pred_begin(UserParent)) == pred_end(UserParent))
5349 // Okay, the CFG is simple enough, try to sink this instruction.
5350 Changed |= TryToSinkInstruction(I, UserParent);
5354 // Now that we have an instruction, try combining it to simplify it...
5355 if (Instruction *Result = visit(*I)) {
5357 // Should we replace the old instruction with a new one?
5359 DEBUG(std::cerr << "IC: Old = " << *I
5360 << " New = " << *Result);
5362 // Everything uses the new instruction now.
5363 I->replaceAllUsesWith(Result);
5365 // Push the new instruction and any users onto the worklist.
5366 WorkList.push_back(Result);
5367 AddUsersToWorkList(*Result);
5369 // Move the name to the new instruction first...
5370 std::string OldName = I->getName(); I->setName("");
5371 Result->setName(OldName);
5373 // Insert the new instruction into the basic block...
5374 BasicBlock *InstParent = I->getParent();
5375 BasicBlock::iterator InsertPos = I;
5377 if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
5378 while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
5381 InstParent->getInstList().insert(InsertPos, Result);
5383 // Make sure that we reprocess all operands now that we reduced their
5385 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
5386 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
5387 WorkList.push_back(OpI);
5389 // Instructions can end up on the worklist more than once. Make sure
5390 // we do not process an instruction that has been deleted.
5391 removeFromWorkList(I);
5393 // Erase the old instruction.
5394 InstParent->getInstList().erase(I);
5396 DEBUG(std::cerr << "IC: MOD = " << *I);
5398 // If the instruction was modified, it's possible that it is now dead.
5399 // if so, remove it.
5400 if (isInstructionTriviallyDead(I)) {
5401 // Make sure we process all operands now that we are reducing their
5403 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
5404 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
5405 WorkList.push_back(OpI);
5407 // Instructions may end up in the worklist more than once. Erase all
5408 // occurrances of this instruction.
5409 removeFromWorkList(I);
5410 I->eraseFromParent();
5412 WorkList.push_back(Result);
5413 AddUsersToWorkList(*Result);
5423 FunctionPass *llvm::createInstructionCombiningPass() {
5424 return new InstCombiner();