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
32 // N. This list is incomplete
34 //===----------------------------------------------------------------------===//
36 #define DEBUG_TYPE "instcombine"
37 #include "llvm/Transforms/Scalar.h"
38 #include "llvm/Instructions.h"
39 #include "llvm/Intrinsics.h"
40 #include "llvm/Pass.h"
41 #include "llvm/Constants.h"
42 #include "llvm/DerivedTypes.h"
43 #include "llvm/GlobalVariable.h"
44 #include "llvm/Target/TargetData.h"
45 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
46 #include "llvm/Transforms/Utils/Local.h"
47 #include "llvm/Support/CallSite.h"
48 #include "llvm/Support/GetElementPtrTypeIterator.h"
49 #include "llvm/Support/InstIterator.h"
50 #include "llvm/Support/InstVisitor.h"
51 #include "llvm/Support/PatternMatch.h"
52 #include "llvm/Support/Debug.h"
53 #include "llvm/ADT/Statistic.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");
63 class InstCombiner : public FunctionPass,
64 public InstVisitor<InstCombiner, Instruction*> {
65 // Worklist of all of the instructions that need to be simplified.
66 std::vector<Instruction*> WorkList;
69 /// AddUsersToWorkList - When an instruction is simplified, add all users of
70 /// the instruction to the work lists because they might get more simplified
73 void AddUsersToWorkList(Instruction &I) {
74 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
76 WorkList.push_back(cast<Instruction>(*UI));
79 /// AddUsesToWorkList - When an instruction is simplified, add operands to
80 /// the work lists because they might get more simplified now.
82 void AddUsesToWorkList(Instruction &I) {
83 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
84 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
85 WorkList.push_back(Op);
88 // removeFromWorkList - remove all instances of I from the worklist.
89 void removeFromWorkList(Instruction *I);
91 virtual bool runOnFunction(Function &F);
93 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
94 AU.addRequired<TargetData>();
98 TargetData &getTargetData() const { return *TD; }
100 // Visitation implementation - Implement instruction combining for different
101 // instruction types. The semantics are as follows:
103 // null - No change was made
104 // I - Change was made, I is still valid, I may be dead though
105 // otherwise - Change was made, replace I with returned instruction
107 Instruction *visitAdd(BinaryOperator &I);
108 Instruction *visitSub(BinaryOperator &I);
109 Instruction *visitMul(BinaryOperator &I);
110 Instruction *visitDiv(BinaryOperator &I);
111 Instruction *visitRem(BinaryOperator &I);
112 Instruction *visitAnd(BinaryOperator &I);
113 Instruction *visitOr (BinaryOperator &I);
114 Instruction *visitXor(BinaryOperator &I);
115 Instruction *visitSetCondInst(BinaryOperator &I);
116 Instruction *visitShiftInst(ShiftInst &I);
117 Instruction *visitCastInst(CastInst &CI);
118 Instruction *visitSelectInst(SelectInst &CI);
119 Instruction *visitCallInst(CallInst &CI);
120 Instruction *visitInvokeInst(InvokeInst &II);
121 Instruction *visitPHINode(PHINode &PN);
122 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
123 Instruction *visitAllocationInst(AllocationInst &AI);
124 Instruction *visitFreeInst(FreeInst &FI);
125 Instruction *visitLoadInst(LoadInst &LI);
126 Instruction *visitBranchInst(BranchInst &BI);
127 Instruction *visitSwitchInst(SwitchInst &SI);
129 // visitInstruction - Specify what to return for unhandled instructions...
130 Instruction *visitInstruction(Instruction &I) { return 0; }
133 Instruction *visitCallSite(CallSite CS);
134 bool transformConstExprCastCall(CallSite CS);
137 // InsertNewInstBefore - insert an instruction New before instruction Old
138 // in the program. Add the new instruction to the worklist.
140 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
141 assert(New && New->getParent() == 0 &&
142 "New instruction already inserted into a basic block!");
143 BasicBlock *BB = Old.getParent();
144 BB->getInstList().insert(&Old, New); // Insert inst
145 WorkList.push_back(New); // Add to worklist
149 /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
150 /// This also adds the cast to the worklist. Finally, this returns the
152 Value *InsertCastBefore(Value *V, const Type *Ty, Instruction &Pos) {
153 if (V->getType() == Ty) return V;
155 Instruction *C = new CastInst(V, Ty, V->getName(), &Pos);
156 WorkList.push_back(C);
160 // ReplaceInstUsesWith - This method is to be used when an instruction is
161 // found to be dead, replacable with another preexisting expression. Here
162 // we add all uses of I to the worklist, replace all uses of I with the new
163 // value, then return I, so that the inst combiner will know that I was
166 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
167 AddUsersToWorkList(I); // Add all modified instrs to worklist
169 I.replaceAllUsesWith(V);
172 // If we are replacing the instruction with itself, this must be in a
173 // segment of unreachable code, so just clobber the instruction.
174 I.replaceAllUsesWith(Constant::getNullValue(I.getType()));
179 // EraseInstFromFunction - When dealing with an instruction that has side
180 // effects or produces a void value, we can't rely on DCE to delete the
181 // instruction. Instead, visit methods should return the value returned by
183 Instruction *EraseInstFromFunction(Instruction &I) {
184 assert(I.use_empty() && "Cannot erase instruction that is used!");
185 AddUsesToWorkList(I);
186 removeFromWorkList(&I);
187 I.getParent()->getInstList().erase(&I);
188 return 0; // Don't do anything with FI
193 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
194 /// InsertBefore instruction. This is specialized a bit to avoid inserting
195 /// casts that are known to not do anything...
197 Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
198 Instruction *InsertBefore);
200 // SimplifyCommutative - This performs a few simplifications for commutative
202 bool SimplifyCommutative(BinaryOperator &I);
205 // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
206 // PHI node as operand #0, see if we can fold the instruction into the PHI
207 // (which is only possible if all operands to the PHI are constants).
208 Instruction *FoldOpIntoPhi(Instruction &I);
210 Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
211 ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
213 Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
214 bool Inside, Instruction &IB);
217 RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
220 // getComplexity: Assign a complexity or rank value to LLVM Values...
221 // 0 -> Constant, 1 -> Other, 2 -> Argument, 2 -> Unary, 3 -> OtherInst
222 static unsigned getComplexity(Value *V) {
223 if (isa<Instruction>(V)) {
224 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
228 if (isa<Argument>(V)) return 2;
229 return isa<Constant>(V) ? 0 : 1;
232 // isOnlyUse - Return true if this instruction will be deleted if we stop using
234 static bool isOnlyUse(Value *V) {
235 return V->hasOneUse() || isa<Constant>(V);
238 // getPromotedType - Return the specified type promoted as it would be to pass
239 // though a va_arg area...
240 static const Type *getPromotedType(const Type *Ty) {
241 switch (Ty->getTypeID()) {
242 case Type::SByteTyID:
243 case Type::ShortTyID: return Type::IntTy;
244 case Type::UByteTyID:
245 case Type::UShortTyID: return Type::UIntTy;
246 case Type::FloatTyID: return Type::DoubleTy;
251 // SimplifyCommutative - This performs a few simplifications for commutative
254 // 1. Order operands such that they are listed from right (least complex) to
255 // left (most complex). This puts constants before unary operators before
258 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
259 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
261 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
262 bool Changed = false;
263 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
264 Changed = !I.swapOperands();
266 if (!I.isAssociative()) return Changed;
267 Instruction::BinaryOps Opcode = I.getOpcode();
268 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
269 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
270 if (isa<Constant>(I.getOperand(1))) {
271 Constant *Folded = ConstantExpr::get(I.getOpcode(),
272 cast<Constant>(I.getOperand(1)),
273 cast<Constant>(Op->getOperand(1)));
274 I.setOperand(0, Op->getOperand(0));
275 I.setOperand(1, Folded);
277 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
278 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
279 isOnlyUse(Op) && isOnlyUse(Op1)) {
280 Constant *C1 = cast<Constant>(Op->getOperand(1));
281 Constant *C2 = cast<Constant>(Op1->getOperand(1));
283 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
284 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
285 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
288 WorkList.push_back(New);
289 I.setOperand(0, New);
290 I.setOperand(1, Folded);
297 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
298 // if the LHS is a constant zero (which is the 'negate' form).
300 static inline Value *dyn_castNegVal(Value *V) {
301 if (BinaryOperator::isNeg(V))
302 return BinaryOperator::getNegArgument(cast<BinaryOperator>(V));
304 // Constants can be considered to be negated values if they can be folded...
305 if (Constant *C = dyn_cast<Constant>(V))
306 return ConstantExpr::getNeg(C);
310 static inline Value *dyn_castNotVal(Value *V) {
311 if (BinaryOperator::isNot(V))
312 return BinaryOperator::getNotArgument(cast<BinaryOperator>(V));
314 // Constants can be considered to be not'ed values...
315 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
316 return ConstantExpr::getNot(C);
320 // dyn_castFoldableMul - If this value is a multiply that can be folded into
321 // other computations (because it has a constant operand), return the
322 // non-constant operand of the multiply.
324 static inline Value *dyn_castFoldableMul(Value *V) {
325 if (V->hasOneUse() && V->getType()->isInteger())
326 if (Instruction *I = dyn_cast<Instruction>(V))
327 if (I->getOpcode() == Instruction::Mul)
328 if (isa<Constant>(I->getOperand(1)))
329 return I->getOperand(0);
333 // Log2 - Calculate the log base 2 for the specified value if it is exactly a
335 static unsigned Log2(uint64_t Val) {
336 assert(Val > 1 && "Values 0 and 1 should be handled elsewhere!");
339 if (Val & 1) return 0; // Multiple bits set?
346 // AddOne, SubOne - Add or subtract a constant one from an integer constant...
347 static ConstantInt *AddOne(ConstantInt *C) {
348 return cast<ConstantInt>(ConstantExpr::getAdd(C,
349 ConstantInt::get(C->getType(), 1)));
351 static ConstantInt *SubOne(ConstantInt *C) {
352 return cast<ConstantInt>(ConstantExpr::getSub(C,
353 ConstantInt::get(C->getType(), 1)));
356 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
357 // true when both operands are equal...
359 static bool isTrueWhenEqual(Instruction &I) {
360 return I.getOpcode() == Instruction::SetEQ ||
361 I.getOpcode() == Instruction::SetGE ||
362 I.getOpcode() == Instruction::SetLE;
365 /// AssociativeOpt - Perform an optimization on an associative operator. This
366 /// function is designed to check a chain of associative operators for a
367 /// potential to apply a certain optimization. Since the optimization may be
368 /// applicable if the expression was reassociated, this checks the chain, then
369 /// reassociates the expression as necessary to expose the optimization
370 /// opportunity. This makes use of a special Functor, which must define
371 /// 'shouldApply' and 'apply' methods.
373 template<typename Functor>
374 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
375 unsigned Opcode = Root.getOpcode();
376 Value *LHS = Root.getOperand(0);
378 // Quick check, see if the immediate LHS matches...
379 if (F.shouldApply(LHS))
380 return F.apply(Root);
382 // Otherwise, if the LHS is not of the same opcode as the root, return.
383 Instruction *LHSI = dyn_cast<Instruction>(LHS);
384 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
385 // Should we apply this transform to the RHS?
386 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
388 // If not to the RHS, check to see if we should apply to the LHS...
389 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
390 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
394 // If the functor wants to apply the optimization to the RHS of LHSI,
395 // reassociate the expression from ((? op A) op B) to (? op (A op B))
397 BasicBlock *BB = Root.getParent();
399 // Now all of the instructions are in the current basic block, go ahead
400 // and perform the reassociation.
401 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
403 // First move the selected RHS to the LHS of the root...
404 Root.setOperand(0, LHSI->getOperand(1));
406 // Make what used to be the LHS of the root be the user of the root...
407 Value *ExtraOperand = TmpLHSI->getOperand(1);
408 if (&Root == TmpLHSI) {
409 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
412 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
413 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
414 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
415 BasicBlock::iterator ARI = &Root; ++ARI;
416 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
419 // Now propagate the ExtraOperand down the chain of instructions until we
421 while (TmpLHSI != LHSI) {
422 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
423 // Move the instruction to immediately before the chain we are
424 // constructing to avoid breaking dominance properties.
425 NextLHSI->getParent()->getInstList().remove(NextLHSI);
426 BB->getInstList().insert(ARI, NextLHSI);
429 Value *NextOp = NextLHSI->getOperand(1);
430 NextLHSI->setOperand(1, ExtraOperand);
432 ExtraOperand = NextOp;
435 // Now that the instructions are reassociated, have the functor perform
436 // the transformation...
437 return F.apply(Root);
440 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
446 // AddRHS - Implements: X + X --> X << 1
449 AddRHS(Value *rhs) : RHS(rhs) {}
450 bool shouldApply(Value *LHS) const { return LHS == RHS; }
451 Instruction *apply(BinaryOperator &Add) const {
452 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
453 ConstantInt::get(Type::UByteTy, 1));
457 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
459 struct AddMaskingAnd {
461 AddMaskingAnd(Constant *c) : C2(c) {}
462 bool shouldApply(Value *LHS) const {
464 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
465 ConstantExpr::getAnd(C1, C2)->isNullValue();
467 Instruction *apply(BinaryOperator &Add) const {
468 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
472 static Value *FoldOperationIntoSelectOperand(Instruction &BI, Value *SO,
474 // Figure out if the constant is the left or the right argument.
475 bool ConstIsRHS = isa<Constant>(BI.getOperand(1));
476 Constant *ConstOperand = cast<Constant>(BI.getOperand(ConstIsRHS));
478 if (Constant *SOC = dyn_cast<Constant>(SO)) {
480 return ConstantExpr::get(BI.getOpcode(), SOC, ConstOperand);
481 return ConstantExpr::get(BI.getOpcode(), ConstOperand, SOC);
484 Value *Op0 = SO, *Op1 = ConstOperand;
488 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&BI))
489 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1);
490 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&BI))
491 New = new ShiftInst(SI->getOpcode(), Op0, Op1);
493 assert(0 && "Unknown binary instruction type!");
496 return IC->InsertNewInstBefore(New, BI);
500 /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
501 /// node as operand #0, see if we can fold the instruction into the PHI (which
502 /// is only possible if all operands to the PHI are constants).
503 Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
504 PHINode *PN = cast<PHINode>(I.getOperand(0));
505 if (!PN->hasOneUse()) return 0;
507 // Check to see if all of the operands of the PHI are constants. If not, we
508 // cannot do the transformation.
509 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
510 if (!isa<Constant>(PN->getIncomingValue(i)))
513 // Okay, we can do the transformation: create the new PHI node.
514 PHINode *NewPN = new PHINode(I.getType(), I.getName());
516 NewPN->op_reserve(PN->getNumOperands());
517 InsertNewInstBefore(NewPN, *PN);
519 // Next, add all of the operands to the PHI.
520 if (I.getNumOperands() == 2) {
521 Constant *C = cast<Constant>(I.getOperand(1));
522 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
523 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
524 NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
525 PN->getIncomingBlock(i));
528 assert(isa<CastInst>(I) && "Unary op should be a cast!");
529 const Type *RetTy = I.getType();
530 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
531 Constant *InV = cast<Constant>(PN->getIncomingValue(i));
532 NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
533 PN->getIncomingBlock(i));
536 return ReplaceInstUsesWith(I, NewPN);
539 // FoldBinOpIntoSelect - Given an instruction with a select as one operand and a
540 // constant as the other operand, try to fold the binary operator into the
542 static Instruction *FoldBinOpIntoSelect(Instruction &BI, SelectInst *SI,
544 // Don't modify shared select instructions
545 if (!SI->hasOneUse()) return 0;
546 Value *TV = SI->getOperand(1);
547 Value *FV = SI->getOperand(2);
549 if (isa<Constant>(TV) || isa<Constant>(FV)) {
550 Value *SelectTrueVal = FoldOperationIntoSelectOperand(BI, TV, IC);
551 Value *SelectFalseVal = FoldOperationIntoSelectOperand(BI, FV, IC);
553 return new SelectInst(SI->getCondition(), SelectTrueVal,
559 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
560 bool Changed = SimplifyCommutative(I);
561 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
563 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
565 if (!I.getType()->isFloatingPoint() && // -0 + +0 = +0, so it's not a noop
567 return ReplaceInstUsesWith(I, LHS);
569 // X + (signbit) --> X ^ signbit
570 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
571 unsigned NumBits = CI->getType()->getPrimitiveSize()*8;
572 uint64_t Val = CI->getRawValue() & (1ULL << NumBits)-1;
573 if (Val == (1ULL << NumBits-1))
574 return BinaryOperator::createXor(LHS, RHS);
577 if (isa<PHINode>(LHS))
578 if (Instruction *NV = FoldOpIntoPhi(I))
583 if (I.getType()->isInteger()) {
584 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
588 if (Value *V = dyn_castNegVal(LHS))
589 return BinaryOperator::createSub(RHS, V);
592 if (!isa<Constant>(RHS))
593 if (Value *V = dyn_castNegVal(RHS))
594 return BinaryOperator::createSub(LHS, V);
596 // X*C + X --> X * (C+1)
597 if (dyn_castFoldableMul(LHS) == RHS) {
599 ConstantExpr::getAdd(
600 cast<Constant>(cast<Instruction>(LHS)->getOperand(1)),
601 ConstantInt::get(I.getType(), 1));
602 return BinaryOperator::createMul(RHS, CP1);
605 // X + X*C --> X * (C+1)
606 if (dyn_castFoldableMul(RHS) == LHS) {
608 ConstantExpr::getAdd(
609 cast<Constant>(cast<Instruction>(RHS)->getOperand(1)),
610 ConstantInt::get(I.getType(), 1));
611 return BinaryOperator::createMul(LHS, CP1);
614 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
616 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
617 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
619 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
621 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
622 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
623 return BinaryOperator::createSub(C, X);
626 // (X & FF00) + xx00 -> (X+xx00) & FF00
627 if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
628 Constant *Anded = ConstantExpr::getAnd(CRHS, C2);
630 // See if all bits from the first bit set in the Add RHS up are included
631 // in the mask. First, get the rightmost bit.
632 uint64_t AddRHSV = CRHS->getRawValue();
634 // Form a mask of all bits from the lowest bit added through the top.
635 uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
636 AddRHSHighBits &= (1ULL << C2->getType()->getPrimitiveSize()*8)-1;
638 // See if the and mask includes all of these bits.
639 uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue();
641 if (AddRHSHighBits == AddRHSHighBitsAnd) {
642 // Okay, the xform is safe. Insert the new add pronto.
643 Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
645 return BinaryOperator::createAnd(NewAdd, C2);
651 // Try to fold constant add into select arguments.
652 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
653 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
657 return Changed ? &I : 0;
660 // isSignBit - Return true if the value represented by the constant only has the
661 // highest order bit set.
662 static bool isSignBit(ConstantInt *CI) {
663 unsigned NumBits = CI->getType()->getPrimitiveSize()*8;
664 return (CI->getRawValue() & ~(-1LL << NumBits)) == (1ULL << (NumBits-1));
667 static unsigned getTypeSizeInBits(const Type *Ty) {
668 return Ty == Type::BoolTy ? 1 : Ty->getPrimitiveSize()*8;
671 /// RemoveNoopCast - Strip off nonconverting casts from the value.
673 static Value *RemoveNoopCast(Value *V) {
674 if (CastInst *CI = dyn_cast<CastInst>(V)) {
675 const Type *CTy = CI->getType();
676 const Type *OpTy = CI->getOperand(0)->getType();
677 if (CTy->isInteger() && OpTy->isInteger()) {
678 if (CTy->getPrimitiveSize() == OpTy->getPrimitiveSize())
679 return RemoveNoopCast(CI->getOperand(0));
680 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
681 return RemoveNoopCast(CI->getOperand(0));
686 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
687 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
689 if (Op0 == Op1) // sub X, X -> 0
690 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
692 // If this is a 'B = x-(-A)', change to B = x+A...
693 if (Value *V = dyn_castNegVal(Op1))
694 return BinaryOperator::createAdd(Op0, V);
696 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
697 // Replace (-1 - A) with (~A)...
698 if (C->isAllOnesValue())
699 return BinaryOperator::createNot(Op1);
701 // C - ~X == X + (1+C)
703 if (match(Op1, m_Not(m_Value(X))))
704 return BinaryOperator::createAdd(X,
705 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
706 // -((uint)X >> 31) -> ((int)X >> 31)
707 // -((int)X >> 31) -> ((uint)X >> 31)
708 if (C->isNullValue()) {
709 Value *NoopCastedRHS = RemoveNoopCast(Op1);
710 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
711 if (SI->getOpcode() == Instruction::Shr)
712 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
714 if (SI->getType()->isSigned())
715 NewTy = SI->getType()->getUnsignedVersion();
717 NewTy = SI->getType()->getSignedVersion();
718 // Check to see if we are shifting out everything but the sign bit.
719 if (CU->getValue() == SI->getType()->getPrimitiveSize()*8-1) {
720 // Ok, the transformation is safe. Insert a cast of the incoming
721 // value, then the new shift, then the new cast.
722 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
723 SI->getOperand(0)->getName());
724 Value *InV = InsertNewInstBefore(FirstCast, I);
725 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
727 if (NewShift->getType() == I.getType())
730 InV = InsertNewInstBefore(NewShift, I);
731 return new CastInst(NewShift, I.getType());
737 // Try to fold constant sub into select arguments.
738 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
739 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
742 if (isa<PHINode>(Op0))
743 if (Instruction *NV = FoldOpIntoPhi(I))
747 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1))
748 if (Op1I->hasOneUse()) {
749 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
750 // is not used by anyone else...
752 if (Op1I->getOpcode() == Instruction::Sub &&
753 !Op1I->getType()->isFloatingPoint()) {
754 // Swap the two operands of the subexpr...
755 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
756 Op1I->setOperand(0, IIOp1);
757 Op1I->setOperand(1, IIOp0);
759 // Create the new top level add instruction...
760 return BinaryOperator::createAdd(Op0, Op1);
763 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
765 if (Op1I->getOpcode() == Instruction::And &&
766 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
767 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
770 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
771 return BinaryOperator::createAnd(Op0, NewNot);
774 // -(X sdiv C) -> (X sdiv -C)
775 if (Op1I->getOpcode() == Instruction::Div)
776 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
777 if (CSI->getValue() == 0)
778 if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
779 return BinaryOperator::createDiv(Op1I->getOperand(0),
780 ConstantExpr::getNeg(DivRHS));
782 // X - X*C --> X * (1-C)
783 if (dyn_castFoldableMul(Op1I) == Op0) {
785 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1),
786 cast<Constant>(cast<Instruction>(Op1)->getOperand(1)));
787 assert(CP1 && "Couldn't constant fold 1-C?");
788 return BinaryOperator::createMul(Op0, CP1);
792 // X*C - X --> X * (C-1)
793 if (dyn_castFoldableMul(Op0) == Op1) {
795 ConstantExpr::getSub(cast<Constant>(cast<Instruction>(Op0)->getOperand(1)),
796 ConstantInt::get(I.getType(), 1));
797 assert(CP1 && "Couldn't constant fold C - 1?");
798 return BinaryOperator::createMul(Op1, CP1);
804 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
805 /// really just returns true if the most significant (sign) bit is set.
806 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
807 if (RHS->getType()->isSigned()) {
808 // True if source is LHS < 0 or LHS <= -1
809 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
810 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
812 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
813 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
814 // the size of the integer type.
815 if (Opcode == Instruction::SetGE)
816 return RHSC->getValue() == 1ULL<<(RHS->getType()->getPrimitiveSize()*8-1);
817 if (Opcode == Instruction::SetGT)
818 return RHSC->getValue() ==
819 (1ULL << (RHS->getType()->getPrimitiveSize()*8-1))-1;
824 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
825 bool Changed = SimplifyCommutative(I);
826 Value *Op0 = I.getOperand(0);
828 // Simplify mul instructions with a constant RHS...
829 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
830 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
832 // ((X << C1)*C2) == (X * (C2 << C1))
833 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
834 if (SI->getOpcode() == Instruction::Shl)
835 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
836 return BinaryOperator::createMul(SI->getOperand(0),
837 ConstantExpr::getShl(CI, ShOp));
839 if (CI->isNullValue())
840 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
841 if (CI->equalsInt(1)) // X * 1 == X
842 return ReplaceInstUsesWith(I, Op0);
843 if (CI->isAllOnesValue()) // X * -1 == 0 - X
844 return BinaryOperator::createNeg(Op0, I.getName());
846 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
847 if (uint64_t C = Log2(Val)) // Replace X*(2^C) with X << C
848 return new ShiftInst(Instruction::Shl, Op0,
849 ConstantUInt::get(Type::UByteTy, C));
850 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
851 if (Op1F->isNullValue())
852 return ReplaceInstUsesWith(I, Op1);
854 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
855 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
856 if (Op1F->getValue() == 1.0)
857 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
860 // Try to fold constant mul into select arguments.
861 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
862 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
865 if (isa<PHINode>(Op0))
866 if (Instruction *NV = FoldOpIntoPhi(I))
870 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
871 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
872 return BinaryOperator::createMul(Op0v, Op1v);
874 // If one of the operands of the multiply is a cast from a boolean value, then
875 // we know the bool is either zero or one, so this is a 'masking' multiply.
876 // See if we can simplify things based on how the boolean was originally
878 CastInst *BoolCast = 0;
879 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
880 if (CI->getOperand(0)->getType() == Type::BoolTy)
883 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
884 if (CI->getOperand(0)->getType() == Type::BoolTy)
887 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
888 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
889 const Type *SCOpTy = SCIOp0->getType();
891 // If the setcc is true iff the sign bit of X is set, then convert this
892 // multiply into a shift/and combination.
893 if (isa<ConstantInt>(SCIOp1) &&
894 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
895 // Shift the X value right to turn it into "all signbits".
896 Constant *Amt = ConstantUInt::get(Type::UByteTy,
897 SCOpTy->getPrimitiveSize()*8-1);
898 if (SCIOp0->getType()->isUnsigned()) {
899 const Type *NewTy = SCIOp0->getType()->getSignedVersion();
900 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
901 SCIOp0->getName()), I);
905 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
906 BoolCast->getOperand(0)->getName()+
909 // If the multiply type is not the same as the source type, sign extend
910 // or truncate to the multiply type.
911 if (I.getType() != V->getType())
912 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
914 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
915 return BinaryOperator::createAnd(V, OtherOp);
920 return Changed ? &I : 0;
923 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
924 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
926 if (RHS->equalsInt(1))
927 return ReplaceInstUsesWith(I, I.getOperand(0));
930 if (RHS->isAllOnesValue())
931 return BinaryOperator::createNeg(I.getOperand(0));
933 if (Instruction *LHS = dyn_cast<Instruction>(I.getOperand(0)))
934 if (LHS->getOpcode() == Instruction::Div)
935 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
936 // (X / C1) / C2 -> X / (C1*C2)
937 return BinaryOperator::createDiv(LHS->getOperand(0),
938 ConstantExpr::getMul(RHS, LHSRHS));
941 // Check to see if this is an unsigned division with an exact power of 2,
942 // if so, convert to a right shift.
943 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
944 if (uint64_t Val = C->getValue()) // Don't break X / 0
945 if (uint64_t C = Log2(Val))
946 return new ShiftInst(Instruction::Shr, I.getOperand(0),
947 ConstantUInt::get(Type::UByteTy, C));
949 if (isa<PHINode>(I.getOperand(0)) && !RHS->isNullValue())
950 if (Instruction *NV = FoldOpIntoPhi(I))
954 // 0 / X == 0, we don't need to preserve faults!
955 if (ConstantInt *LHS = dyn_cast<ConstantInt>(I.getOperand(0)))
956 if (LHS->equalsInt(0))
957 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
963 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
964 if (I.getType()->isSigned())
965 if (Value *RHSNeg = dyn_castNegVal(I.getOperand(1)))
966 if (!isa<ConstantSInt>(RHSNeg) ||
967 cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
969 AddUsesToWorkList(I);
970 I.setOperand(1, RHSNeg);
974 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
975 if (RHS->equalsInt(1)) // X % 1 == 0
976 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
978 // Check to see if this is an unsigned remainder with an exact power of 2,
979 // if so, convert to a bitwise and.
980 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
981 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
982 if (!(Val & (Val-1))) // Power of 2
983 return BinaryOperator::createAnd(I.getOperand(0),
984 ConstantUInt::get(I.getType(), Val-1));
985 if (isa<PHINode>(I.getOperand(0)) && !RHS->isNullValue())
986 if (Instruction *NV = FoldOpIntoPhi(I))
990 // 0 % X == 0, we don't need to preserve faults!
991 if (ConstantInt *LHS = dyn_cast<ConstantInt>(I.getOperand(0)))
992 if (LHS->equalsInt(0))
993 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
998 // isMaxValueMinusOne - return true if this is Max-1
999 static bool isMaxValueMinusOne(const ConstantInt *C) {
1000 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
1001 // Calculate -1 casted to the right type...
1002 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
1003 uint64_t Val = ~0ULL; // All ones
1004 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1005 return CU->getValue() == Val-1;
1008 const ConstantSInt *CS = cast<ConstantSInt>(C);
1010 // Calculate 0111111111..11111
1011 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
1012 int64_t Val = INT64_MAX; // All ones
1013 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
1014 return CS->getValue() == Val-1;
1017 // isMinValuePlusOne - return true if this is Min+1
1018 static bool isMinValuePlusOne(const ConstantInt *C) {
1019 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
1020 return CU->getValue() == 1;
1022 const ConstantSInt *CS = cast<ConstantSInt>(C);
1024 // Calculate 1111111111000000000000
1025 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
1026 int64_t Val = -1; // All ones
1027 Val <<= TypeBits-1; // Shift over to the right spot
1028 return CS->getValue() == Val+1;
1031 // isOneBitSet - Return true if there is exactly one bit set in the specified
1033 static bool isOneBitSet(const ConstantInt *CI) {
1034 uint64_t V = CI->getRawValue();
1035 return V && (V & (V-1)) == 0;
1038 #if 0 // Currently unused
1039 // isLowOnes - Return true if the constant is of the form 0+1+.
1040 static bool isLowOnes(const ConstantInt *CI) {
1041 uint64_t V = CI->getRawValue();
1043 // There won't be bits set in parts that the type doesn't contain.
1044 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1046 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1047 return U && V && (U & V) == 0;
1051 // isHighOnes - Return true if the constant is of the form 1+0+.
1052 // This is the same as lowones(~X).
1053 static bool isHighOnes(const ConstantInt *CI) {
1054 uint64_t V = ~CI->getRawValue();
1056 // There won't be bits set in parts that the type doesn't contain.
1057 V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
1059 uint64_t U = V+1; // If it is low ones, this should be a power of two.
1060 return U && V && (U & V) == 0;
1064 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
1065 /// are carefully arranged to allow folding of expressions such as:
1067 /// (A < B) | (A > B) --> (A != B)
1069 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
1070 /// represents that the comparison is true if A == B, and bit value '1' is true
1073 static unsigned getSetCondCode(const SetCondInst *SCI) {
1074 switch (SCI->getOpcode()) {
1076 case Instruction::SetGT: return 1;
1077 case Instruction::SetEQ: return 2;
1078 case Instruction::SetGE: return 3;
1079 case Instruction::SetLT: return 4;
1080 case Instruction::SetNE: return 5;
1081 case Instruction::SetLE: return 6;
1084 assert(0 && "Invalid SetCC opcode!");
1089 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
1090 /// opcode and two operands into either a constant true or false, or a brand new
1091 /// SetCC instruction.
1092 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
1094 case 0: return ConstantBool::False;
1095 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
1096 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
1097 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
1098 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
1099 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
1100 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
1101 case 7: return ConstantBool::True;
1102 default: assert(0 && "Illegal SetCCCode!"); return 0;
1106 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1107 struct FoldSetCCLogical {
1110 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
1111 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
1112 bool shouldApply(Value *V) const {
1113 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
1114 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
1115 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
1118 Instruction *apply(BinaryOperator &Log) const {
1119 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
1120 if (SCI->getOperand(0) != LHS) {
1121 assert(SCI->getOperand(1) == LHS);
1122 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
1125 unsigned LHSCode = getSetCondCode(SCI);
1126 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
1128 switch (Log.getOpcode()) {
1129 case Instruction::And: Code = LHSCode & RHSCode; break;
1130 case Instruction::Or: Code = LHSCode | RHSCode; break;
1131 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
1132 default: assert(0 && "Illegal logical opcode!"); return 0;
1135 Value *RV = getSetCCValue(Code, LHS, RHS);
1136 if (Instruction *I = dyn_cast<Instruction>(RV))
1138 // Otherwise, it's a constant boolean value...
1139 return IC.ReplaceInstUsesWith(Log, RV);
1144 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
1145 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
1146 // guaranteed to be either a shift instruction or a binary operator.
1147 Instruction *InstCombiner::OptAndOp(Instruction *Op,
1148 ConstantIntegral *OpRHS,
1149 ConstantIntegral *AndRHS,
1150 BinaryOperator &TheAnd) {
1151 Value *X = Op->getOperand(0);
1152 Constant *Together = 0;
1153 if (!isa<ShiftInst>(Op))
1154 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
1156 switch (Op->getOpcode()) {
1157 case Instruction::Xor:
1158 if (Together->isNullValue()) {
1159 // (X ^ C1) & C2 --> (X & C2) iff (C1&C2) == 0
1160 return BinaryOperator::createAnd(X, AndRHS);
1161 } else if (Op->hasOneUse()) {
1162 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
1163 std::string OpName = Op->getName(); Op->setName("");
1164 Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
1165 InsertNewInstBefore(And, TheAnd);
1166 return BinaryOperator::createXor(And, Together);
1169 case Instruction::Or:
1170 // (X | C1) & C2 --> X & C2 iff C1 & C1 == 0
1171 if (Together->isNullValue())
1172 return BinaryOperator::createAnd(X, AndRHS);
1174 if (Together == AndRHS) // (X | C) & C --> C
1175 return ReplaceInstUsesWith(TheAnd, AndRHS);
1177 if (Op->hasOneUse() && Together != OpRHS) {
1178 // (X | C1) & C2 --> (X | (C1&C2)) & C2
1179 std::string Op0Name = Op->getName(); Op->setName("");
1180 Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
1181 InsertNewInstBefore(Or, TheAnd);
1182 return BinaryOperator::createAnd(Or, AndRHS);
1186 case Instruction::Add:
1187 if (Op->hasOneUse()) {
1188 // Adding a one to a single bit bit-field should be turned into an XOR
1189 // of the bit. First thing to check is to see if this AND is with a
1190 // single bit constant.
1191 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
1193 // Clear bits that are not part of the constant.
1194 AndRHSV &= (1ULL << AndRHS->getType()->getPrimitiveSize()*8)-1;
1196 // If there is only one bit set...
1197 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
1198 // Ok, at this point, we know that we are masking the result of the
1199 // ADD down to exactly one bit. If the constant we are adding has
1200 // no bits set below this bit, then we can eliminate the ADD.
1201 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
1203 // Check to see if any bits below the one bit set in AndRHSV are set.
1204 if ((AddRHS & (AndRHSV-1)) == 0) {
1205 // If not, the only thing that can effect the output of the AND is
1206 // the bit specified by AndRHSV. If that bit is set, the effect of
1207 // the XOR is to toggle the bit. If it is clear, then the ADD has
1209 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
1210 TheAnd.setOperand(0, X);
1213 std::string Name = Op->getName(); Op->setName("");
1214 // Pull the XOR out of the AND.
1215 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
1216 InsertNewInstBefore(NewAnd, TheAnd);
1217 return BinaryOperator::createXor(NewAnd, AndRHS);
1224 case Instruction::Shl: {
1225 // We know that the AND will not produce any of the bits shifted in, so if
1226 // the anded constant includes them, clear them now!
1228 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1229 Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
1230 Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
1232 if (CI == ShlMask) { // Masking out bits that the shift already masks
1233 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
1234 } else if (CI != AndRHS) { // Reducing bits set in and.
1235 TheAnd.setOperand(1, CI);
1240 case Instruction::Shr:
1241 // We know that the AND will not produce any of the bits shifted in, so if
1242 // the anded constant includes them, clear them now! This only applies to
1243 // unsigned shifts, because a signed shr may bring in set bits!
1245 if (AndRHS->getType()->isUnsigned()) {
1246 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1247 Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS);
1248 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1250 if (CI == ShrMask) { // Masking out bits that the shift already masks.
1251 return ReplaceInstUsesWith(TheAnd, Op);
1252 } else if (CI != AndRHS) {
1253 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
1256 } else { // Signed shr.
1257 // See if this is shifting in some sign extension, then masking it out
1259 if (Op->hasOneUse()) {
1260 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1261 Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS);
1262 Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
1263 if (CI == ShrMask) { // Masking out bits shifted in.
1264 // Make the argument unsigned.
1265 Value *ShVal = Op->getOperand(0);
1266 ShVal = InsertCastBefore(ShVal,
1267 ShVal->getType()->getUnsignedVersion(),
1269 ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal,
1270 OpRHS, Op->getName()),
1272 return new CastInst(ShVal, Op->getType());
1282 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
1283 /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
1284 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. IB is the location to
1285 /// insert new instructions.
1286 Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
1287 bool Inside, Instruction &IB) {
1288 assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
1289 "Lo is not <= Hi in range emission code!");
1291 if (Lo == Hi) // Trivially false.
1292 return new SetCondInst(Instruction::SetNE, V, V);
1293 if (cast<ConstantIntegral>(Lo)->isMinValue())
1294 return new SetCondInst(Instruction::SetLT, V, Hi);
1296 Constant *AddCST = ConstantExpr::getNeg(Lo);
1297 Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
1298 InsertNewInstBefore(Add, IB);
1299 // Convert to unsigned for the comparison.
1300 const Type *UnsType = Add->getType()->getUnsignedVersion();
1301 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1302 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1303 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1304 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1307 if (Lo == Hi) // Trivially true.
1308 return new SetCondInst(Instruction::SetEQ, V, V);
1310 Hi = SubOne(cast<ConstantInt>(Hi));
1311 if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
1312 return new SetCondInst(Instruction::SetGT, V, Hi);
1314 // Emit X-Lo > Hi-Lo-1
1315 Constant *AddCST = ConstantExpr::getNeg(Lo);
1316 Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
1317 InsertNewInstBefore(Add, IB);
1318 // Convert to unsigned for the comparison.
1319 const Type *UnsType = Add->getType()->getUnsignedVersion();
1320 Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
1321 AddCST = ConstantExpr::getAdd(AddCST, Hi);
1322 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1323 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1327 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1328 bool Changed = SimplifyCommutative(I);
1329 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1331 // and X, X = X and X, 0 == 0
1332 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
1333 return ReplaceInstUsesWith(I, Op1);
1336 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1337 if (RHS->isAllOnesValue())
1338 return ReplaceInstUsesWith(I, Op0);
1340 // Optimize a variety of ((val OP C1) & C2) combinations...
1341 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
1342 Instruction *Op0I = cast<Instruction>(Op0);
1343 Value *X = Op0I->getOperand(0);
1344 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1345 if (Instruction *Res = OptAndOp(Op0I, Op0CI, RHS, I))
1349 // Try to fold constant and into select arguments.
1350 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1351 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1353 if (isa<PHINode>(Op0))
1354 if (Instruction *NV = FoldOpIntoPhi(I))
1358 Value *Op0NotVal = dyn_castNotVal(Op0);
1359 Value *Op1NotVal = dyn_castNotVal(Op1);
1361 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1362 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1364 // (~A & ~B) == (~(A | B)) - De Morgan's Law
1365 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1366 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
1367 I.getName()+".demorgan");
1368 InsertNewInstBefore(Or, I);
1369 return BinaryOperator::createNot(Or);
1372 if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
1373 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1374 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1377 Value *LHSVal, *RHSVal;
1378 ConstantInt *LHSCst, *RHSCst;
1379 Instruction::BinaryOps LHSCC, RHSCC;
1380 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1381 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1382 if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
1383 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1384 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1385 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1386 // Ensure that the larger constant is on the RHS.
1387 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1388 SetCondInst *LHS = cast<SetCondInst>(Op0);
1389 if (cast<ConstantBool>(Cmp)->getValue()) {
1390 std::swap(LHS, RHS);
1391 std::swap(LHSCst, RHSCst);
1392 std::swap(LHSCC, RHSCC);
1395 // At this point, we know we have have two setcc instructions
1396 // comparing a value against two constants and and'ing the result
1397 // together. Because of the above check, we know that we only have
1398 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1399 // FoldSetCCLogical check above), that the two constants are not
1401 assert(LHSCst != RHSCst && "Compares not folded above?");
1404 default: assert(0 && "Unknown integer condition code!");
1405 case Instruction::SetEQ:
1407 default: assert(0 && "Unknown integer condition code!");
1408 case Instruction::SetEQ: // (X == 13 & X == 15) -> false
1409 case Instruction::SetGT: // (X == 13 & X > 15) -> false
1410 return ReplaceInstUsesWith(I, ConstantBool::False);
1411 case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
1412 case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
1413 return ReplaceInstUsesWith(I, LHS);
1415 case Instruction::SetNE:
1417 default: assert(0 && "Unknown integer condition code!");
1418 case Instruction::SetLT:
1419 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
1420 return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
1421 break; // (X != 13 & X < 15) -> no change
1422 case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
1423 case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
1424 return ReplaceInstUsesWith(I, RHS);
1425 case Instruction::SetNE:
1426 if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
1427 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1428 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
1429 LHSVal->getName()+".off");
1430 InsertNewInstBefore(Add, I);
1431 const Type *UnsType = Add->getType()->getUnsignedVersion();
1432 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
1433 AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
1434 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1435 return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
1437 break; // (X != 13 & X != 15) -> no change
1440 case Instruction::SetLT:
1442 default: assert(0 && "Unknown integer condition code!");
1443 case Instruction::SetEQ: // (X < 13 & X == 15) -> false
1444 case Instruction::SetGT: // (X < 13 & X > 15) -> false
1445 return ReplaceInstUsesWith(I, ConstantBool::False);
1446 case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
1447 case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
1448 return ReplaceInstUsesWith(I, LHS);
1450 case Instruction::SetGT:
1452 default: assert(0 && "Unknown integer condition code!");
1453 case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
1454 return ReplaceInstUsesWith(I, LHS);
1455 case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
1456 return ReplaceInstUsesWith(I, RHS);
1457 case Instruction::SetNE:
1458 if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
1459 return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
1460 break; // (X > 13 & X != 15) -> no change
1461 case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
1462 return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
1468 return Changed ? &I : 0;
1471 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
1472 bool Changed = SimplifyCommutative(I);
1473 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1475 // or X, X = X or X, 0 == X
1476 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
1477 return ReplaceInstUsesWith(I, Op0);
1480 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1481 if (RHS->isAllOnesValue())
1482 return ReplaceInstUsesWith(I, Op1);
1484 ConstantInt *C1; Value *X;
1485 // (X & C1) | C2 --> (X | C2) & (C1|C2)
1486 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1487 std::string Op0Name = Op0->getName(); Op0->setName("");
1488 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
1489 InsertNewInstBefore(Or, I);
1490 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
1493 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
1494 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1495 std::string Op0Name = Op0->getName(); Op0->setName("");
1496 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
1497 InsertNewInstBefore(Or, I);
1498 return BinaryOperator::createXor(Or,
1499 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
1502 // Try to fold constant and into select arguments.
1503 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1504 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1506 if (isa<PHINode>(Op0))
1507 if (Instruction *NV = FoldOpIntoPhi(I))
1511 // (A & C1)|(A & C2) == A & (C1|C2)
1512 Value *A, *B; ConstantInt *C1, *C2;
1513 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
1514 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) && A == B)
1515 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
1517 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
1518 if (A == Op1) // ~A | A == -1
1519 return ReplaceInstUsesWith(I,
1520 ConstantIntegral::getAllOnesValue(I.getType()));
1525 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
1527 return ReplaceInstUsesWith(I,
1528 ConstantIntegral::getAllOnesValue(I.getType()));
1530 // (~A | ~B) == (~(A & B)) - De Morgan's Law
1531 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1532 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
1533 I.getName()+".demorgan"), I);
1534 return BinaryOperator::createNot(And);
1538 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
1539 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
1540 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1543 Value *LHSVal, *RHSVal;
1544 ConstantInt *LHSCst, *RHSCst;
1545 Instruction::BinaryOps LHSCC, RHSCC;
1546 if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
1547 if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
1548 if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
1549 // Set[GL]E X, CST is folded to Set[GL]T elsewhere.
1550 LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
1551 RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
1552 // Ensure that the larger constant is on the RHS.
1553 Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
1554 SetCondInst *LHS = cast<SetCondInst>(Op0);
1555 if (cast<ConstantBool>(Cmp)->getValue()) {
1556 std::swap(LHS, RHS);
1557 std::swap(LHSCst, RHSCst);
1558 std::swap(LHSCC, RHSCC);
1561 // At this point, we know we have have two setcc instructions
1562 // comparing a value against two constants and or'ing the result
1563 // together. Because of the above check, we know that we only have
1564 // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
1565 // FoldSetCCLogical check above), that the two constants are not
1567 assert(LHSCst != RHSCst && "Compares not folded above?");
1570 default: assert(0 && "Unknown integer condition code!");
1571 case Instruction::SetEQ:
1573 default: assert(0 && "Unknown integer condition code!");
1574 case Instruction::SetEQ:
1575 if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
1576 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1577 Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
1578 LHSVal->getName()+".off");
1579 InsertNewInstBefore(Add, I);
1580 const Type *UnsType = Add->getType()->getUnsignedVersion();
1581 Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
1582 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
1583 AddCST = ConstantExpr::getCast(AddCST, UnsType);
1584 return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
1586 break; // (X == 13 | X == 15) -> no change
1588 case Instruction::SetGT:
1589 if (LHSCst == SubOne(RHSCst)) // (X == 13 | X > 14) -> X > 13
1590 return new SetCondInst(Instruction::SetGT, LHSVal, LHSCst);
1591 break; // (X == 13 | X > 15) -> no change
1592 case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
1593 case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
1594 return ReplaceInstUsesWith(I, RHS);
1597 case Instruction::SetNE:
1599 default: assert(0 && "Unknown integer condition code!");
1600 case Instruction::SetLT: // (X != 13 | X < 15) -> X < 15
1601 return ReplaceInstUsesWith(I, RHS);
1602 case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
1603 case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
1604 return ReplaceInstUsesWith(I, LHS);
1605 case Instruction::SetNE: // (X != 13 | X != 15) -> true
1606 return ReplaceInstUsesWith(I, ConstantBool::True);
1609 case Instruction::SetLT:
1611 default: assert(0 && "Unknown integer condition code!");
1612 case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
1614 case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
1615 return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
1616 case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
1617 case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
1618 return ReplaceInstUsesWith(I, RHS);
1621 case Instruction::SetGT:
1623 default: assert(0 && "Unknown integer condition code!");
1624 case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
1625 case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
1626 return ReplaceInstUsesWith(I, LHS);
1627 case Instruction::SetNE: // (X > 13 | X != 15) -> true
1628 case Instruction::SetLT: // (X > 13 | X < 15) -> true
1629 return ReplaceInstUsesWith(I, ConstantBool::True);
1634 return Changed ? &I : 0;
1637 // XorSelf - Implements: X ^ X --> 0
1640 XorSelf(Value *rhs) : RHS(rhs) {}
1641 bool shouldApply(Value *LHS) const { return LHS == RHS; }
1642 Instruction *apply(BinaryOperator &Xor) const {
1648 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
1649 bool Changed = SimplifyCommutative(I);
1650 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1652 // xor X, X = 0, even if X is nested in a sequence of Xor's.
1653 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
1654 assert(Result == &I && "AssociativeOpt didn't work?");
1655 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1658 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1660 if (RHS->isNullValue())
1661 return ReplaceInstUsesWith(I, Op0);
1663 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
1664 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
1665 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
1666 if (RHS == ConstantBool::True && SCI->hasOneUse())
1667 return new SetCondInst(SCI->getInverseCondition(),
1668 SCI->getOperand(0), SCI->getOperand(1));
1670 // ~(c-X) == X-c-1 == X+(-c-1)
1671 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
1672 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
1673 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
1674 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
1675 ConstantInt::get(I.getType(), 1));
1676 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
1679 // ~(~X & Y) --> (X | ~Y)
1680 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
1681 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
1682 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
1684 BinaryOperator::createNot(Op0I->getOperand(1),
1685 Op0I->getOperand(1)->getName()+".not");
1686 InsertNewInstBefore(NotY, I);
1687 return BinaryOperator::createOr(Op0NotVal, NotY);
1691 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1692 switch (Op0I->getOpcode()) {
1693 case Instruction::Add:
1694 // ~(X-c) --> (-c-1)-X
1695 if (RHS->isAllOnesValue()) {
1696 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
1697 return BinaryOperator::createSub(
1698 ConstantExpr::getSub(NegOp0CI,
1699 ConstantInt::get(I.getType(), 1)),
1700 Op0I->getOperand(0));
1703 case Instruction::And:
1704 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
1705 if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue())
1706 return BinaryOperator::createOr(Op0, RHS);
1708 case Instruction::Or:
1709 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
1710 if (ConstantExpr::getAnd(RHS, Op0CI) == RHS)
1711 return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS));
1717 // Try to fold constant and into select arguments.
1718 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1719 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1721 if (isa<PHINode>(Op0))
1722 if (Instruction *NV = FoldOpIntoPhi(I))
1726 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
1728 return ReplaceInstUsesWith(I,
1729 ConstantIntegral::getAllOnesValue(I.getType()));
1731 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
1733 return ReplaceInstUsesWith(I,
1734 ConstantIntegral::getAllOnesValue(I.getType()));
1736 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
1737 if (Op1I->getOpcode() == Instruction::Or) {
1738 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
1739 cast<BinaryOperator>(Op1I)->swapOperands();
1741 std::swap(Op0, Op1);
1742 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
1744 std::swap(Op0, Op1);
1746 } else if (Op1I->getOpcode() == Instruction::Xor) {
1747 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
1748 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
1749 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
1750 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
1753 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
1754 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
1755 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
1756 cast<BinaryOperator>(Op0I)->swapOperands();
1757 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
1758 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
1759 Op1->getName()+".not"), I);
1760 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
1762 } else if (Op0I->getOpcode() == Instruction::Xor) {
1763 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
1764 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
1765 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
1766 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
1769 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
1770 Value *A, *B; ConstantInt *C1, *C2;
1771 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
1772 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) &&
1773 ConstantExpr::getAnd(C1, C2)->isNullValue())
1774 return BinaryOperator::createOr(Op0, Op1);
1776 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
1777 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
1778 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1781 return Changed ? &I : 0;
1784 /// MulWithOverflow - Compute Result = In1*In2, returning true if the result
1785 /// overflowed for this type.
1786 static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
1788 Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
1789 return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
1792 static bool isPositive(ConstantInt *C) {
1793 return cast<ConstantSInt>(C)->getValue() >= 0;
1796 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
1797 /// overflowed for this type.
1798 static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
1800 Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
1802 if (In1->getType()->isUnsigned())
1803 return cast<ConstantUInt>(Result)->getValue() <
1804 cast<ConstantUInt>(In1)->getValue();
1805 if (isPositive(In1) != isPositive(In2))
1807 if (isPositive(In1))
1808 return cast<ConstantSInt>(Result)->getValue() <
1809 cast<ConstantSInt>(In1)->getValue();
1810 return cast<ConstantSInt>(Result)->getValue() >
1811 cast<ConstantSInt>(In1)->getValue();
1814 Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
1815 bool Changed = SimplifyCommutative(I);
1816 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1817 const Type *Ty = Op0->getType();
1821 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
1823 // setcc <global/alloca*>, 0 - Global/Stack value addresses are never null!
1824 if (isa<ConstantPointerNull>(Op1) &&
1825 (isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0)))
1826 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
1829 // setcc's with boolean values can always be turned into bitwise operations
1830 if (Ty == Type::BoolTy) {
1831 switch (I.getOpcode()) {
1832 default: assert(0 && "Invalid setcc instruction!");
1833 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
1834 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
1835 InsertNewInstBefore(Xor, I);
1836 return BinaryOperator::createNot(Xor);
1838 case Instruction::SetNE:
1839 return BinaryOperator::createXor(Op0, Op1);
1841 case Instruction::SetGT:
1842 std::swap(Op0, Op1); // Change setgt -> setlt
1844 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
1845 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
1846 InsertNewInstBefore(Not, I);
1847 return BinaryOperator::createAnd(Not, Op1);
1849 case Instruction::SetGE:
1850 std::swap(Op0, Op1); // Change setge -> setle
1852 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
1853 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
1854 InsertNewInstBefore(Not, I);
1855 return BinaryOperator::createOr(Not, Op1);
1860 // See if we are doing a comparison between a constant and an instruction that
1861 // can be folded into the comparison.
1862 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
1863 // Check to see if we are comparing against the minimum or maximum value...
1864 if (CI->isMinValue()) {
1865 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
1866 return ReplaceInstUsesWith(I, ConstantBool::False);
1867 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
1868 return ReplaceInstUsesWith(I, ConstantBool::True);
1869 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
1870 return BinaryOperator::createSetEQ(Op0, Op1);
1871 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
1872 return BinaryOperator::createSetNE(Op0, Op1);
1874 } else if (CI->isMaxValue()) {
1875 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
1876 return ReplaceInstUsesWith(I, ConstantBool::False);
1877 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
1878 return ReplaceInstUsesWith(I, ConstantBool::True);
1879 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
1880 return BinaryOperator::createSetEQ(Op0, Op1);
1881 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
1882 return BinaryOperator::createSetNE(Op0, Op1);
1884 // Comparing against a value really close to min or max?
1885 } else if (isMinValuePlusOne(CI)) {
1886 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
1887 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
1888 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
1889 return BinaryOperator::createSetNE(Op0, SubOne(CI));
1891 } else if (isMaxValueMinusOne(CI)) {
1892 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
1893 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
1894 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
1895 return BinaryOperator::createSetNE(Op0, AddOne(CI));
1898 // If we still have a setle or setge instruction, turn it into the
1899 // appropriate setlt or setgt instruction. Since the border cases have
1900 // already been handled above, this requires little checking.
1902 if (I.getOpcode() == Instruction::SetLE)
1903 return BinaryOperator::createSetLT(Op0, AddOne(CI));
1904 if (I.getOpcode() == Instruction::SetGE)
1905 return BinaryOperator::createSetGT(Op0, SubOne(CI));
1907 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
1908 switch (LHSI->getOpcode()) {
1909 case Instruction::PHI:
1910 if (Instruction *NV = FoldOpIntoPhi(I))
1913 case Instruction::And:
1914 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
1915 LHSI->getOperand(0)->hasOneUse()) {
1916 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
1917 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
1918 // happens a LOT in code produced by the C front-end, for bitfield
1920 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
1921 ConstantUInt *ShAmt;
1922 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
1923 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
1924 const Type *Ty = LHSI->getType();
1926 // We can fold this as long as we can't shift unknown bits
1927 // into the mask. This can only happen with signed shift
1928 // rights, as they sign-extend.
1930 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
1931 Shift->getType()->isUnsigned();
1933 // To test for the bad case of the signed shr, see if any
1934 // of the bits shifted in could be tested after the mask.
1935 Constant *OShAmt = ConstantUInt::get(Type::UByteTy,
1936 Ty->getPrimitiveSize()*8-ShAmt->getValue());
1938 ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
1939 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
1945 if (Shift->getOpcode() == Instruction::Shl)
1946 NewCst = ConstantExpr::getUShr(CI, ShAmt);
1948 NewCst = ConstantExpr::getShl(CI, ShAmt);
1950 // Check to see if we are shifting out any of the bits being
1952 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
1953 // If we shifted bits out, the fold is not going to work out.
1954 // As a special case, check to see if this means that the
1955 // result is always true or false now.
1956 if (I.getOpcode() == Instruction::SetEQ)
1957 return ReplaceInstUsesWith(I, ConstantBool::False);
1958 if (I.getOpcode() == Instruction::SetNE)
1959 return ReplaceInstUsesWith(I, ConstantBool::True);
1961 I.setOperand(1, NewCst);
1962 Constant *NewAndCST;
1963 if (Shift->getOpcode() == Instruction::Shl)
1964 NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
1966 NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
1967 LHSI->setOperand(1, NewAndCST);
1968 LHSI->setOperand(0, Shift->getOperand(0));
1969 WorkList.push_back(Shift); // Shift is dead.
1970 AddUsesToWorkList(I);
1978 case Instruction::Cast: { // (setcc (cast X to larger), CI)
1979 const Type *SrcTy = LHSI->getOperand(0)->getType();
1980 if (SrcTy->isIntegral() && LHSI->getType()->isIntegral()) {
1981 unsigned SrcBits = SrcTy->getPrimitiveSize()*8;
1982 if (SrcTy == Type::BoolTy) SrcBits = 1;
1983 unsigned DestBits = LHSI->getType()->getPrimitiveSize()*8;
1984 if (LHSI->getType() == Type::BoolTy) DestBits = 1;
1985 if (SrcBits < DestBits) {
1986 // Check to see if the comparison is always true or false.
1987 Constant *NewCst = ConstantExpr::getCast(CI, SrcTy);
1988 if (ConstantExpr::getCast(NewCst, LHSI->getType()) != CI) {
1989 Constant *Min = ConstantIntegral::getMinValue(SrcTy);
1990 Constant *Max = ConstantIntegral::getMaxValue(SrcTy);
1991 Min = ConstantExpr::getCast(Min, LHSI->getType());
1992 Max = ConstantExpr::getCast(Max, LHSI->getType());
1993 switch (I.getOpcode()) {
1994 default: assert(0 && "unknown integer comparison");
1995 case Instruction::SetEQ:
1996 return ReplaceInstUsesWith(I, ConstantBool::False);
1997 case Instruction::SetNE:
1998 return ReplaceInstUsesWith(I, ConstantBool::True);
1999 case Instruction::SetLT:
2000 return ReplaceInstUsesWith(I, ConstantExpr::getSetLT(Max, CI));
2001 case Instruction::SetGT:
2002 return ReplaceInstUsesWith(I, ConstantExpr::getSetGT(Min, CI));
2006 return new SetCondInst(I.getOpcode(), LHSI->getOperand(0),
2007 ConstantExpr::getCast(CI, SrcTy));
2012 case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
2013 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2014 switch (I.getOpcode()) {
2016 case Instruction::SetEQ:
2017 case Instruction::SetNE: {
2018 // If we are comparing against bits always shifted out, the
2019 // comparison cannot succeed.
2021 ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
2022 if (Comp != CI) {// Comparing against a bit that we know is zero.
2023 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2024 Constant *Cst = ConstantBool::get(IsSetNE);
2025 return ReplaceInstUsesWith(I, Cst);
2028 if (LHSI->hasOneUse()) {
2029 // Otherwise strength reduce the shift into an and.
2030 unsigned ShAmtVal = ShAmt->getValue();
2031 unsigned TypeBits = CI->getType()->getPrimitiveSize()*8;
2032 uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
2035 if (CI->getType()->isUnsigned()) {
2036 Mask = ConstantUInt::get(CI->getType(), Val);
2037 } else if (ShAmtVal != 0) {
2038 Mask = ConstantSInt::get(CI->getType(), Val);
2040 Mask = ConstantInt::getAllOnesValue(CI->getType());
2044 BinaryOperator::createAnd(LHSI->getOperand(0),
2045 Mask, LHSI->getName()+".mask");
2046 Value *And = InsertNewInstBefore(AndI, I);
2047 return new SetCondInst(I.getOpcode(), And,
2048 ConstantExpr::getUShr(CI, ShAmt));
2055 case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
2056 if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
2057 switch (I.getOpcode()) {
2059 case Instruction::SetEQ:
2060 case Instruction::SetNE: {
2061 // If we are comparing against bits always shifted out, the
2062 // comparison cannot succeed.
2064 ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
2066 if (Comp != CI) {// Comparing against a bit that we know is zero.
2067 bool IsSetNE = I.getOpcode() == Instruction::SetNE;
2068 Constant *Cst = ConstantBool::get(IsSetNE);
2069 return ReplaceInstUsesWith(I, Cst);
2072 if (LHSI->hasOneUse() || CI->isNullValue()) {
2073 unsigned ShAmtVal = ShAmt->getValue();
2075 // Otherwise strength reduce the shift into an and.
2076 uint64_t Val = ~0ULL; // All ones.
2077 Val <<= ShAmtVal; // Shift over to the right spot.
2080 if (CI->getType()->isUnsigned()) {
2081 unsigned TypeBits = CI->getType()->getPrimitiveSize()*8;
2082 Val &= (1ULL << TypeBits)-1;
2083 Mask = ConstantUInt::get(CI->getType(), Val);
2085 Mask = ConstantSInt::get(CI->getType(), Val);
2089 BinaryOperator::createAnd(LHSI->getOperand(0),
2090 Mask, LHSI->getName()+".mask");
2091 Value *And = InsertNewInstBefore(AndI, I);
2092 return new SetCondInst(I.getOpcode(), And,
2093 ConstantExpr::getShl(CI, ShAmt));
2101 case Instruction::Div:
2102 // Fold: (div X, C1) op C2 -> range check
2103 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
2104 // Fold this div into the comparison, producing a range check.
2105 // Determine, based on the divide type, what the range is being
2106 // checked. If there is an overflow on the low or high side, remember
2107 // it, otherwise compute the range [low, hi) bounding the new value.
2108 bool LoOverflow = false, HiOverflow = 0;
2109 ConstantInt *LoBound = 0, *HiBound = 0;
2112 bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
2114 if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
2115 } else if (LHSI->getType()->isUnsigned()) { // udiv
2117 LoOverflow = ProdOV;
2118 HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
2119 } else if (isPositive(DivRHS)) { // Divisor is > 0.
2120 if (CI->isNullValue()) { // (X / pos) op 0
2122 LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
2124 } else if (isPositive(CI)) { // (X / pos) op pos
2126 LoOverflow = ProdOV;
2127 HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
2128 } else { // (X / pos) op neg
2129 Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
2130 LoOverflow = AddWithOverflow(LoBound, Prod,
2131 cast<ConstantInt>(DivRHSH));
2133 HiOverflow = ProdOV;
2135 } else { // Divisor is < 0.
2136 if (CI->isNullValue()) { // (X / neg) op 0
2137 LoBound = AddOne(DivRHS);
2138 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
2139 } else if (isPositive(CI)) { // (X / neg) op pos
2140 HiOverflow = LoOverflow = ProdOV;
2142 LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
2143 HiBound = AddOne(Prod);
2144 } else { // (X / neg) op neg
2146 LoOverflow = HiOverflow = ProdOV;
2147 HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
2152 Value *X = LHSI->getOperand(0);
2153 switch (I.getOpcode()) {
2154 default: assert(0 && "Unhandled setcc opcode!");
2155 case Instruction::SetEQ:
2156 if (LoOverflow && HiOverflow)
2157 return ReplaceInstUsesWith(I, ConstantBool::False);
2158 else if (HiOverflow)
2159 return new SetCondInst(Instruction::SetGE, X, LoBound);
2160 else if (LoOverflow)
2161 return new SetCondInst(Instruction::SetLT, X, HiBound);
2163 return InsertRangeTest(X, LoBound, HiBound, true, I);
2164 case Instruction::SetNE:
2165 if (LoOverflow && HiOverflow)
2166 return ReplaceInstUsesWith(I, ConstantBool::True);
2167 else if (HiOverflow)
2168 return new SetCondInst(Instruction::SetLT, X, LoBound);
2169 else if (LoOverflow)
2170 return new SetCondInst(Instruction::SetGE, X, HiBound);
2172 return InsertRangeTest(X, LoBound, HiBound, false, I);
2173 case Instruction::SetLT:
2175 return ReplaceInstUsesWith(I, ConstantBool::False);
2176 return new SetCondInst(Instruction::SetLT, X, LoBound);
2177 case Instruction::SetGT:
2179 return ReplaceInstUsesWith(I, ConstantBool::False);
2180 return new SetCondInst(Instruction::SetGE, X, HiBound);
2185 case Instruction::Select:
2186 // If either operand of the select is a constant, we can fold the
2187 // comparison into the select arms, which will cause one to be
2188 // constant folded and the select turned into a bitwise or.
2189 Value *Op1 = 0, *Op2 = 0;
2190 if (LHSI->hasOneUse()) {
2191 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
2192 // Fold the known value into the constant operand.
2193 Op1 = ConstantExpr::get(I.getOpcode(), C, CI);
2194 // Insert a new SetCC of the other select operand.
2195 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
2196 LHSI->getOperand(2), CI,
2198 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
2199 // Fold the known value into the constant operand.
2200 Op2 = ConstantExpr::get(I.getOpcode(), C, CI);
2201 // Insert a new SetCC of the other select operand.
2202 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
2203 LHSI->getOperand(1), CI,
2209 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
2213 // Simplify seteq and setne instructions...
2214 if (I.getOpcode() == Instruction::SetEQ ||
2215 I.getOpcode() == Instruction::SetNE) {
2216 bool isSetNE = I.getOpcode() == Instruction::SetNE;
2218 // If the first operand is (and|or|xor) with a constant, and the second
2219 // operand is a constant, simplify a bit.
2220 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
2221 switch (BO->getOpcode()) {
2222 case Instruction::Rem:
2223 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
2224 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
2226 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1)
2228 Log2(cast<ConstantSInt>(BO->getOperand(1))->getValue())) {
2229 const Type *UTy = BO->getType()->getUnsignedVersion();
2230 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
2232 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
2233 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
2234 RHSCst, BO->getName()), I);
2235 return BinaryOperator::create(I.getOpcode(), NewRem,
2236 Constant::getNullValue(UTy));
2240 case Instruction::Add:
2241 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
2242 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2243 if (BO->hasOneUse())
2244 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
2245 ConstantExpr::getSub(CI, BOp1C));
2246 } else if (CI->isNullValue()) {
2247 // Replace ((add A, B) != 0) with (A != -B) if A or B is
2248 // efficiently invertible, or if the add has just this one use.
2249 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
2251 if (Value *NegVal = dyn_castNegVal(BOp1))
2252 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
2253 else if (Value *NegVal = dyn_castNegVal(BOp0))
2254 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
2255 else if (BO->hasOneUse()) {
2256 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
2258 InsertNewInstBefore(Neg, I);
2259 return new SetCondInst(I.getOpcode(), BOp0, Neg);
2263 case Instruction::Xor:
2264 // For the xor case, we can xor two constants together, eliminating
2265 // the explicit xor.
2266 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
2267 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
2268 ConstantExpr::getXor(CI, BOC));
2271 case Instruction::Sub:
2272 // Replace (([sub|xor] A, B) != 0) with (A != B)
2273 if (CI->isNullValue())
2274 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
2278 case Instruction::Or:
2279 // If bits are being or'd in that are not present in the constant we
2280 // are comparing against, then the comparison could never succeed!
2281 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
2282 Constant *NotCI = ConstantExpr::getNot(CI);
2283 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
2284 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
2288 case Instruction::And:
2289 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2290 // If bits are being compared against that are and'd out, then the
2291 // comparison can never succeed!
2292 if (!ConstantExpr::getAnd(CI,
2293 ConstantExpr::getNot(BOC))->isNullValue())
2294 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
2296 // If we have ((X & C) == C), turn it into ((X & C) != 0).
2297 if (CI == BOC && isOneBitSet(CI))
2298 return new SetCondInst(isSetNE ? Instruction::SetEQ :
2299 Instruction::SetNE, Op0,
2300 Constant::getNullValue(CI->getType()));
2302 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
2303 // to be a signed value as appropriate.
2304 if (isSignBit(BOC)) {
2305 Value *X = BO->getOperand(0);
2306 // If 'X' is not signed, insert a cast now...
2307 if (!BOC->getType()->isSigned()) {
2308 const Type *DestTy = BOC->getType()->getSignedVersion();
2309 X = InsertCastBefore(X, DestTy, I);
2311 return new SetCondInst(isSetNE ? Instruction::SetLT :
2312 Instruction::SetGE, X,
2313 Constant::getNullValue(X->getType()));
2316 // ((X & ~7) == 0) --> X < 8
2317 if (CI->isNullValue() && isHighOnes(BOC)) {
2318 Value *X = BO->getOperand(0);
2319 Constant *NegX = ConstantExpr::getNeg(BOC);
2321 // If 'X' is signed, insert a cast now.
2322 if (NegX->getType()->isSigned()) {
2323 const Type *DestTy = NegX->getType()->getUnsignedVersion();
2324 X = InsertCastBefore(X, DestTy, I);
2325 NegX = ConstantExpr::getCast(NegX, DestTy);
2328 return new SetCondInst(isSetNE ? Instruction::SetGE :
2329 Instruction::SetLT, X, NegX);
2336 } else { // Not a SetEQ/SetNE
2337 // If the LHS is a cast from an integral value of the same size,
2338 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
2339 Value *CastOp = Cast->getOperand(0);
2340 const Type *SrcTy = CastOp->getType();
2341 unsigned SrcTySize = SrcTy->getPrimitiveSize();
2342 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
2343 SrcTySize == Cast->getType()->getPrimitiveSize()) {
2344 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
2345 "Source and destination signednesses should differ!");
2346 if (Cast->getType()->isSigned()) {
2347 // If this is a signed comparison, check for comparisons in the
2348 // vicinity of zero.
2349 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
2351 return BinaryOperator::createSetGT(CastOp,
2352 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize*8-1))-1));
2353 else if (I.getOpcode() == Instruction::SetGT &&
2354 cast<ConstantSInt>(CI)->getValue() == -1)
2355 // X > -1 => x < 128
2356 return BinaryOperator::createSetLT(CastOp,
2357 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize*8-1)));
2359 ConstantUInt *CUI = cast<ConstantUInt>(CI);
2360 if (I.getOpcode() == Instruction::SetLT &&
2361 CUI->getValue() == 1ULL << (SrcTySize*8-1))
2362 // X < 128 => X > -1
2363 return BinaryOperator::createSetGT(CastOp,
2364 ConstantSInt::get(SrcTy, -1));
2365 else if (I.getOpcode() == Instruction::SetGT &&
2366 CUI->getValue() == (1ULL << (SrcTySize*8-1))-1)
2368 return BinaryOperator::createSetLT(CastOp,
2369 Constant::getNullValue(SrcTy));
2376 // Test to see if the operands of the setcc are casted versions of other
2377 // values. If the cast can be stripped off both arguments, we do so now.
2378 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
2379 Value *CastOp0 = CI->getOperand(0);
2380 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
2381 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
2382 (I.getOpcode() == Instruction::SetEQ ||
2383 I.getOpcode() == Instruction::SetNE)) {
2384 // We keep moving the cast from the left operand over to the right
2385 // operand, where it can often be eliminated completely.
2388 // If operand #1 is a cast instruction, see if we can eliminate it as
2390 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
2391 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
2393 Op1 = CI2->getOperand(0);
2395 // If Op1 is a constant, we can fold the cast into the constant.
2396 if (Op1->getType() != Op0->getType())
2397 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
2398 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
2400 // Otherwise, cast the RHS right before the setcc
2401 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
2402 InsertNewInstBefore(cast<Instruction>(Op1), I);
2404 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
2407 // Handle the special case of: setcc (cast bool to X), <cst>
2408 // This comes up when you have code like
2411 // For generality, we handle any zero-extension of any operand comparison
2413 if (ConstantInt *ConstantRHS = dyn_cast<ConstantInt>(Op1)) {
2414 const Type *SrcTy = CastOp0->getType();
2415 const Type *DestTy = Op0->getType();
2416 if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
2417 (SrcTy->isUnsigned() || SrcTy == Type::BoolTy)) {
2418 // Ok, we have an expansion of operand 0 into a new type. Get the
2419 // constant value, masink off bits which are not set in the RHS. These
2420 // could be set if the destination value is signed.
2421 uint64_t ConstVal = ConstantRHS->getRawValue();
2422 ConstVal &= (1ULL << DestTy->getPrimitiveSize()*8)-1;
2424 // If the constant we are comparing it with has high bits set, which
2425 // don't exist in the original value, the values could never be equal,
2426 // because the source would be zero extended.
2428 SrcTy == Type::BoolTy ? 1 : SrcTy->getPrimitiveSize()*8;
2429 bool HasSignBit = ConstVal & (1ULL << (DestTy->getPrimitiveSize()*8-1));
2430 if (ConstVal & ~((1ULL << SrcBits)-1)) {
2431 switch (I.getOpcode()) {
2432 default: assert(0 && "Unknown comparison type!");
2433 case Instruction::SetEQ:
2434 return ReplaceInstUsesWith(I, ConstantBool::False);
2435 case Instruction::SetNE:
2436 return ReplaceInstUsesWith(I, ConstantBool::True);
2437 case Instruction::SetLT:
2438 case Instruction::SetLE:
2439 if (DestTy->isSigned() && HasSignBit)
2440 return ReplaceInstUsesWith(I, ConstantBool::False);
2441 return ReplaceInstUsesWith(I, ConstantBool::True);
2442 case Instruction::SetGT:
2443 case Instruction::SetGE:
2444 if (DestTy->isSigned() && HasSignBit)
2445 return ReplaceInstUsesWith(I, ConstantBool::True);
2446 return ReplaceInstUsesWith(I, ConstantBool::False);
2450 // Otherwise, we can replace the setcc with a setcc of the smaller
2452 Op1 = ConstantExpr::getCast(cast<Constant>(Op1), SrcTy);
2453 return BinaryOperator::create(I.getOpcode(), CastOp0, Op1);
2457 return Changed ? &I : 0;
2462 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
2463 assert(I.getOperand(1)->getType() == Type::UByteTy);
2464 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2465 bool isLeftShift = I.getOpcode() == Instruction::Shl;
2467 // shl X, 0 == X and shr X, 0 == X
2468 // shl 0, X == 0 and shr 0, X == 0
2469 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
2470 Op0 == Constant::getNullValue(Op0->getType()))
2471 return ReplaceInstUsesWith(I, Op0);
2473 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
2475 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
2476 if (CSI->isAllOnesValue())
2477 return ReplaceInstUsesWith(I, CSI);
2479 // Try to fold constant and into select arguments.
2480 if (isa<Constant>(Op0))
2481 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
2482 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
2485 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
2486 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
2487 // of a signed value.
2489 unsigned TypeBits = Op0->getType()->getPrimitiveSize()*8;
2490 if (CUI->getValue() >= TypeBits) {
2491 if (!Op0->getType()->isSigned() || isLeftShift)
2492 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
2494 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
2499 // ((X*C1) << C2) == (X * (C1 << C2))
2500 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
2501 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
2502 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
2503 return BinaryOperator::createMul(BO->getOperand(0),
2504 ConstantExpr::getShl(BOOp, CUI));
2506 // Try to fold constant and into select arguments.
2507 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2508 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
2510 if (isa<PHINode>(Op0))
2511 if (Instruction *NV = FoldOpIntoPhi(I))
2514 // If the operand is an bitwise operator with a constant RHS, and the
2515 // shift is the only use, we can pull it out of the shift.
2516 if (Op0->hasOneUse())
2517 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0))
2518 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
2519 bool isValid = true; // Valid only for And, Or, Xor
2520 bool highBitSet = false; // Transform if high bit of constant set?
2522 switch (Op0BO->getOpcode()) {
2523 default: isValid = false; break; // Do not perform transform!
2524 case Instruction::Add:
2525 isValid = isLeftShift;
2527 case Instruction::Or:
2528 case Instruction::Xor:
2531 case Instruction::And:
2536 // If this is a signed shift right, and the high bit is modified
2537 // by the logical operation, do not perform the transformation.
2538 // The highBitSet boolean indicates the value of the high bit of
2539 // the constant which would cause it to be modified for this
2542 if (isValid && !isLeftShift && !I.getType()->isUnsigned()) {
2543 uint64_t Val = Op0C->getRawValue();
2544 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
2548 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI);
2550 Instruction *NewShift =
2551 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI,
2554 InsertNewInstBefore(NewShift, I);
2556 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
2561 // If this is a shift of a shift, see if we can fold the two together...
2562 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
2563 if (ConstantUInt *ShiftAmt1C =
2564 dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) {
2565 unsigned ShiftAmt1 = ShiftAmt1C->getValue();
2566 unsigned ShiftAmt2 = CUI->getValue();
2568 // Check for (A << c1) << c2 and (A >> c1) >> c2
2569 if (I.getOpcode() == Op0SI->getOpcode()) {
2570 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
2571 if (Op0->getType()->getPrimitiveSize()*8 < Amt)
2572 Amt = Op0->getType()->getPrimitiveSize()*8;
2573 return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
2574 ConstantUInt::get(Type::UByteTy, Amt));
2577 // Check for (A << c1) >> c2 or visaversa. If we are dealing with
2578 // signed types, we can only support the (A >> c1) << c2 configuration,
2579 // because it can not turn an arbitrary bit of A into a sign bit.
2580 if (I.getType()->isUnsigned() || isLeftShift) {
2581 // Calculate bitmask for what gets shifted off the edge...
2582 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
2584 C = ConstantExpr::getShl(C, ShiftAmt1C);
2586 C = ConstantExpr::getShr(C, ShiftAmt1C);
2589 BinaryOperator::createAnd(Op0SI->getOperand(0), C,
2590 Op0SI->getOperand(0)->getName()+".mask");
2591 InsertNewInstBefore(Mask, I);
2593 // Figure out what flavor of shift we should use...
2594 if (ShiftAmt1 == ShiftAmt2)
2595 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
2596 else if (ShiftAmt1 < ShiftAmt2) {
2597 return new ShiftInst(I.getOpcode(), Mask,
2598 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
2600 return new ShiftInst(Op0SI->getOpcode(), Mask,
2601 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
2617 /// getCastType - In the future, we will split the cast instruction into these
2618 /// various types. Until then, we have to do the analysis here.
2619 static CastType getCastType(const Type *Src, const Type *Dest) {
2620 assert(Src->isIntegral() && Dest->isIntegral() &&
2621 "Only works on integral types!");
2622 unsigned SrcSize = Src->getPrimitiveSize()*8;
2623 if (Src == Type::BoolTy) SrcSize = 1;
2624 unsigned DestSize = Dest->getPrimitiveSize()*8;
2625 if (Dest == Type::BoolTy) DestSize = 1;
2627 if (SrcSize == DestSize) return Noop;
2628 if (SrcSize > DestSize) return Truncate;
2629 if (Src->isSigned()) return Signext;
2634 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
2637 static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
2638 const Type *DstTy, TargetData *TD) {
2640 // It is legal to eliminate the instruction if casting A->B->A if the sizes
2641 // are identical and the bits don't get reinterpreted (for example
2642 // int->float->int would not be allowed).
2643 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
2646 // If we are casting between pointer and integer types, treat pointers as
2647 // integers of the appropriate size for the code below.
2648 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
2649 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
2650 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
2652 // Allow free casting and conversion of sizes as long as the sign doesn't
2654 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
2655 CastType FirstCast = getCastType(SrcTy, MidTy);
2656 CastType SecondCast = getCastType(MidTy, DstTy);
2658 // Capture the effect of these two casts. If the result is a legal cast,
2659 // the CastType is stored here, otherwise a special code is used.
2660 static const unsigned CastResult[] = {
2661 // First cast is noop
2663 // First cast is a truncate
2664 1, 1, 4, 4, // trunc->extend is not safe to eliminate
2665 // First cast is a sign ext
2666 2, 5, 2, 4, // signext->zeroext never ok
2667 // First cast is a zero ext
2671 unsigned Result = CastResult[FirstCast*4+SecondCast];
2673 default: assert(0 && "Illegal table value!");
2678 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
2679 // truncates, we could eliminate more casts.
2680 return (unsigned)getCastType(SrcTy, DstTy) == Result;
2682 return false; // Not possible to eliminate this here.
2684 // Sign or zero extend followed by truncate is always ok if the result
2685 // is a truncate or noop.
2686 CastType ResultCast = getCastType(SrcTy, DstTy);
2687 if (ResultCast == Noop || ResultCast == Truncate)
2689 // Otherwise we are still growing the value, we are only safe if the
2690 // result will match the sign/zeroextendness of the result.
2691 return ResultCast == FirstCast;
2697 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
2698 if (V->getType() == Ty || isa<Constant>(V)) return false;
2699 if (const CastInst *CI = dyn_cast<CastInst>(V))
2700 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
2706 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
2707 /// InsertBefore instruction. This is specialized a bit to avoid inserting
2708 /// casts that are known to not do anything...
2710 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
2711 Instruction *InsertBefore) {
2712 if (V->getType() == DestTy) return V;
2713 if (Constant *C = dyn_cast<Constant>(V))
2714 return ConstantExpr::getCast(C, DestTy);
2716 CastInst *CI = new CastInst(V, DestTy, V->getName());
2717 InsertNewInstBefore(CI, *InsertBefore);
2721 // CastInst simplification
2723 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
2724 Value *Src = CI.getOperand(0);
2726 // If the user is casting a value to the same type, eliminate this cast
2728 if (CI.getType() == Src->getType())
2729 return ReplaceInstUsesWith(CI, Src);
2731 // If casting the result of another cast instruction, try to eliminate this
2734 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) {
2735 if (isEliminableCastOfCast(CSrc->getOperand(0)->getType(),
2736 CSrc->getType(), CI.getType(), TD)) {
2737 // This instruction now refers directly to the cast's src operand. This
2738 // has a good chance of making CSrc dead.
2739 CI.setOperand(0, CSrc->getOperand(0));
2743 // If this is an A->B->A cast, and we are dealing with integral types, try
2744 // to convert this into a logical 'and' instruction.
2746 if (CSrc->getOperand(0)->getType() == CI.getType() &&
2747 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
2748 CI.getType()->isUnsigned() && CSrc->getType()->isUnsigned() &&
2749 CSrc->getType()->getPrimitiveSize() < CI.getType()->getPrimitiveSize()){
2750 assert(CSrc->getType() != Type::ULongTy &&
2751 "Cannot have type bigger than ulong!");
2752 uint64_t AndValue = (1ULL << CSrc->getType()->getPrimitiveSize()*8)-1;
2753 Constant *AndOp = ConstantUInt::get(CI.getType(), AndValue);
2754 return BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
2758 // If this is a cast to bool, turn it into the appropriate setne instruction.
2759 if (CI.getType() == Type::BoolTy)
2760 return BinaryOperator::createSetNE(CI.getOperand(0),
2761 Constant::getNullValue(CI.getOperand(0)->getType()));
2763 // If casting the result of a getelementptr instruction with no offset, turn
2764 // this into a cast of the original pointer!
2766 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
2767 bool AllZeroOperands = true;
2768 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
2769 if (!isa<Constant>(GEP->getOperand(i)) ||
2770 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
2771 AllZeroOperands = false;
2774 if (AllZeroOperands) {
2775 CI.setOperand(0, GEP->getOperand(0));
2780 // If we are casting a malloc or alloca to a pointer to a type of the same
2781 // size, rewrite the allocation instruction to allocate the "right" type.
2783 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
2784 if (AI->hasOneUse() && !AI->isArrayAllocation())
2785 if (const PointerType *PTy = dyn_cast<PointerType>(CI.getType())) {
2786 // Get the type really allocated and the type casted to...
2787 const Type *AllocElTy = AI->getAllocatedType();
2788 const Type *CastElTy = PTy->getElementType();
2789 if (AllocElTy->isSized() && CastElTy->isSized()) {
2790 unsigned AllocElTySize = TD->getTypeSize(AllocElTy);
2791 unsigned CastElTySize = TD->getTypeSize(CastElTy);
2793 // If the allocation is for an even multiple of the cast type size
2794 if (CastElTySize && (AllocElTySize % CastElTySize == 0)) {
2795 Value *Amt = ConstantUInt::get(Type::UIntTy,
2796 AllocElTySize/CastElTySize);
2797 std::string Name = AI->getName(); AI->setName("");
2798 AllocationInst *New;
2799 if (isa<MallocInst>(AI))
2800 New = new MallocInst(CastElTy, Amt, Name);
2802 New = new AllocaInst(CastElTy, Amt, Name);
2803 InsertNewInstBefore(New, *AI);
2804 return ReplaceInstUsesWith(CI, New);
2809 if (isa<PHINode>(Src))
2810 if (Instruction *NV = FoldOpIntoPhi(CI))
2813 // If the source value is an instruction with only this use, we can attempt to
2814 // propagate the cast into the instruction. Also, only handle integral types
2816 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
2817 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
2818 CI.getType()->isInteger()) { // Don't mess with casts to bool here
2819 const Type *DestTy = CI.getType();
2820 unsigned SrcBitSize = getTypeSizeInBits(Src->getType());
2821 unsigned DestBitSize = getTypeSizeInBits(DestTy);
2823 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
2824 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
2826 switch (SrcI->getOpcode()) {
2827 case Instruction::Add:
2828 case Instruction::Mul:
2829 case Instruction::And:
2830 case Instruction::Or:
2831 case Instruction::Xor:
2832 // If we are discarding information, or just changing the sign, rewrite.
2833 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
2834 // Don't insert two casts if they cannot be eliminated. We allow two
2835 // casts to be inserted if the sizes are the same. This could only be
2836 // converting signedness, which is a noop.
2837 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
2838 !ValueRequiresCast(Op0, DestTy, TD)) {
2839 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
2840 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
2841 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
2842 ->getOpcode(), Op0c, Op1c);
2846 case Instruction::Shl:
2847 // Allow changing the sign of the source operand. Do not allow changing
2848 // the size of the shift, UNLESS the shift amount is a constant. We
2849 // mush not change variable sized shifts to a smaller size, because it
2850 // is undefined to shift more bits out than exist in the value.
2851 if (DestBitSize == SrcBitSize ||
2852 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
2853 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
2854 return new ShiftInst(Instruction::Shl, Op0c, Op1);
2863 /// GetSelectFoldableOperands - We want to turn code that looks like this:
2865 /// %D = select %cond, %C, %A
2867 /// %C = select %cond, %B, 0
2870 /// Assuming that the specified instruction is an operand to the select, return
2871 /// a bitmask indicating which operands of this instruction are foldable if they
2872 /// equal the other incoming value of the select.
2874 static unsigned GetSelectFoldableOperands(Instruction *I) {
2875 switch (I->getOpcode()) {
2876 case Instruction::Add:
2877 case Instruction::Mul:
2878 case Instruction::And:
2879 case Instruction::Or:
2880 case Instruction::Xor:
2881 return 3; // Can fold through either operand.
2882 case Instruction::Sub: // Can only fold on the amount subtracted.
2883 case Instruction::Shl: // Can only fold on the shift amount.
2884 case Instruction::Shr:
2887 return 0; // Cannot fold
2891 /// GetSelectFoldableConstant - For the same transformation as the previous
2892 /// function, return the identity constant that goes into the select.
2893 static Constant *GetSelectFoldableConstant(Instruction *I) {
2894 switch (I->getOpcode()) {
2895 default: assert(0 && "This cannot happen!"); abort();
2896 case Instruction::Add:
2897 case Instruction::Sub:
2898 case Instruction::Or:
2899 case Instruction::Xor:
2900 return Constant::getNullValue(I->getType());
2901 case Instruction::Shl:
2902 case Instruction::Shr:
2903 return Constant::getNullValue(Type::UByteTy);
2904 case Instruction::And:
2905 return ConstantInt::getAllOnesValue(I->getType());
2906 case Instruction::Mul:
2907 return ConstantInt::get(I->getType(), 1);
2911 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
2912 Value *CondVal = SI.getCondition();
2913 Value *TrueVal = SI.getTrueValue();
2914 Value *FalseVal = SI.getFalseValue();
2916 // select true, X, Y -> X
2917 // select false, X, Y -> Y
2918 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
2919 if (C == ConstantBool::True)
2920 return ReplaceInstUsesWith(SI, TrueVal);
2922 assert(C == ConstantBool::False);
2923 return ReplaceInstUsesWith(SI, FalseVal);
2926 // select C, X, X -> X
2927 if (TrueVal == FalseVal)
2928 return ReplaceInstUsesWith(SI, TrueVal);
2930 if (SI.getType() == Type::BoolTy)
2931 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
2932 if (C == ConstantBool::True) {
2933 // Change: A = select B, true, C --> A = or B, C
2934 return BinaryOperator::createOr(CondVal, FalseVal);
2936 // Change: A = select B, false, C --> A = and !B, C
2938 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
2939 "not."+CondVal->getName()), SI);
2940 return BinaryOperator::createAnd(NotCond, FalseVal);
2942 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
2943 if (C == ConstantBool::False) {
2944 // Change: A = select B, C, false --> A = and B, C
2945 return BinaryOperator::createAnd(CondVal, TrueVal);
2947 // Change: A = select B, C, true --> A = or !B, C
2949 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
2950 "not."+CondVal->getName()), SI);
2951 return BinaryOperator::createOr(NotCond, TrueVal);
2955 // Selecting between two integer constants?
2956 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
2957 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
2958 // select C, 1, 0 -> cast C to int
2959 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
2960 return new CastInst(CondVal, SI.getType());
2961 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
2962 // select C, 0, 1 -> cast !C to int
2964 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
2965 "not."+CondVal->getName()), SI);
2966 return new CastInst(NotCond, SI.getType());
2969 // If one of the constants is zero (we know they can't both be) and we
2970 // have a setcc instruction with zero, and we have an 'and' with the
2971 // non-constant value, eliminate this whole mess. This corresponds to
2972 // cases like this: ((X & 27) ? 27 : 0)
2973 if (TrueValC->isNullValue() || FalseValC->isNullValue())
2974 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
2975 if ((IC->getOpcode() == Instruction::SetEQ ||
2976 IC->getOpcode() == Instruction::SetNE) &&
2977 isa<ConstantInt>(IC->getOperand(1)) &&
2978 cast<Constant>(IC->getOperand(1))->isNullValue())
2979 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
2980 if (ICA->getOpcode() == Instruction::And &&
2981 isa<ConstantInt>(ICA->getOperand(1)) &&
2982 (ICA->getOperand(1) == TrueValC ||
2983 ICA->getOperand(1) == FalseValC) &&
2984 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
2985 // Okay, now we know that everything is set up, we just don't
2986 // know whether we have a setne or seteq and whether the true or
2987 // false val is the zero.
2988 bool ShouldNotVal = !TrueValC->isNullValue();
2989 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
2992 V = InsertNewInstBefore(BinaryOperator::create(
2993 Instruction::Xor, V, ICA->getOperand(1)), SI);
2994 return ReplaceInstUsesWith(SI, V);
2998 // See if we are selecting two values based on a comparison of the two values.
2999 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
3000 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
3001 // Transform (X == Y) ? X : Y -> Y
3002 if (SCI->getOpcode() == Instruction::SetEQ)
3003 return ReplaceInstUsesWith(SI, FalseVal);
3004 // Transform (X != Y) ? X : Y -> X
3005 if (SCI->getOpcode() == Instruction::SetNE)
3006 return ReplaceInstUsesWith(SI, TrueVal);
3007 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
3009 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
3010 // Transform (X == Y) ? Y : X -> X
3011 if (SCI->getOpcode() == Instruction::SetEQ)
3012 return ReplaceInstUsesWith(SI, FalseVal);
3013 // Transform (X != Y) ? Y : X -> Y
3014 if (SCI->getOpcode() == Instruction::SetNE)
3015 return ReplaceInstUsesWith(SI, TrueVal);
3016 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
3020 // See if we can fold the select into one of our operands.
3021 if (SI.getType()->isInteger()) {
3022 // See the comment above GetSelectFoldableOperands for a description of the
3023 // transformation we are doing here.
3024 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
3025 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
3026 !isa<Constant>(FalseVal))
3027 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
3028 unsigned OpToFold = 0;
3029 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
3031 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
3036 Constant *C = GetSelectFoldableConstant(TVI);
3037 std::string Name = TVI->getName(); TVI->setName("");
3038 Instruction *NewSel =
3039 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
3041 InsertNewInstBefore(NewSel, SI);
3042 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
3043 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
3044 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
3045 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
3047 assert(0 && "Unknown instruction!!");
3052 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
3053 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
3054 !isa<Constant>(TrueVal))
3055 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
3056 unsigned OpToFold = 0;
3057 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
3059 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
3064 Constant *C = GetSelectFoldableConstant(FVI);
3065 std::string Name = FVI->getName(); FVI->setName("");
3066 Instruction *NewSel =
3067 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
3069 InsertNewInstBefore(NewSel, SI);
3070 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
3071 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
3072 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
3073 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
3075 assert(0 && "Unknown instruction!!");
3084 // CallInst simplification
3086 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
3087 // Intrinsics cannot occur in an invoke, so handle them here instead of in
3089 if (Function *F = CI.getCalledFunction())
3090 switch (F->getIntrinsicID()) {
3091 case Intrinsic::memmove:
3092 case Intrinsic::memcpy:
3093 case Intrinsic::memset:
3094 // memmove/cpy/set of zero bytes is a noop.
3095 if (Constant *NumBytes = dyn_cast<Constant>(CI.getOperand(3))) {
3096 if (NumBytes->isNullValue())
3097 return EraseInstFromFunction(CI);
3104 return visitCallSite(&CI);
3107 // InvokeInst simplification
3109 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
3110 return visitCallSite(&II);
3113 // visitCallSite - Improvements for call and invoke instructions.
3115 Instruction *InstCombiner::visitCallSite(CallSite CS) {
3116 bool Changed = false;
3118 // If the callee is a constexpr cast of a function, attempt to move the cast
3119 // to the arguments of the call/invoke.
3120 if (transformConstExprCastCall(CS)) return 0;
3122 Value *Callee = CS.getCalledValue();
3123 const PointerType *PTy = cast<PointerType>(Callee->getType());
3124 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
3125 if (FTy->isVarArg()) {
3126 // See if we can optimize any arguments passed through the varargs area of
3128 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
3129 E = CS.arg_end(); I != E; ++I)
3130 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
3131 // If this cast does not effect the value passed through the varargs
3132 // area, we can eliminate the use of the cast.
3133 Value *Op = CI->getOperand(0);
3134 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
3141 return Changed ? CS.getInstruction() : 0;
3144 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
3145 // attempt to move the cast to the arguments of the call/invoke.
3147 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
3148 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
3149 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
3150 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
3152 Function *Callee = cast<Function>(CE->getOperand(0));
3153 Instruction *Caller = CS.getInstruction();
3155 // Okay, this is a cast from a function to a different type. Unless doing so
3156 // would cause a type conversion of one of our arguments, change this call to
3157 // be a direct call with arguments casted to the appropriate types.
3159 const FunctionType *FT = Callee->getFunctionType();
3160 const Type *OldRetTy = Caller->getType();
3162 // Check to see if we are changing the return type...
3163 if (OldRetTy != FT->getReturnType()) {
3164 if (Callee->isExternal() &&
3165 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
3166 !Caller->use_empty())
3167 return false; // Cannot transform this return value...
3169 // If the callsite is an invoke instruction, and the return value is used by
3170 // a PHI node in a successor, we cannot change the return type of the call
3171 // because there is no place to put the cast instruction (without breaking
3172 // the critical edge). Bail out in this case.
3173 if (!Caller->use_empty())
3174 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
3175 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
3177 if (PHINode *PN = dyn_cast<PHINode>(*UI))
3178 if (PN->getParent() == II->getNormalDest() ||
3179 PN->getParent() == II->getUnwindDest())
3183 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
3184 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
3186 CallSite::arg_iterator AI = CS.arg_begin();
3187 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
3188 const Type *ParamTy = FT->getParamType(i);
3189 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
3190 if (Callee->isExternal() && !isConvertible) return false;
3193 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
3194 Callee->isExternal())
3195 return false; // Do not delete arguments unless we have a function body...
3197 // Okay, we decided that this is a safe thing to do: go ahead and start
3198 // inserting cast instructions as necessary...
3199 std::vector<Value*> Args;
3200 Args.reserve(NumActualArgs);
3202 AI = CS.arg_begin();
3203 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
3204 const Type *ParamTy = FT->getParamType(i);
3205 if ((*AI)->getType() == ParamTy) {
3206 Args.push_back(*AI);
3208 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
3213 // If the function takes more arguments than the call was taking, add them
3215 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
3216 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
3218 // If we are removing arguments to the function, emit an obnoxious warning...
3219 if (FT->getNumParams() < NumActualArgs)
3220 if (!FT->isVarArg()) {
3221 std::cerr << "WARNING: While resolving call to function '"
3222 << Callee->getName() << "' arguments were dropped!\n";
3224 // Add all of the arguments in their promoted form to the arg list...
3225 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
3226 const Type *PTy = getPromotedType((*AI)->getType());
3227 if (PTy != (*AI)->getType()) {
3228 // Must promote to pass through va_arg area!
3229 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
3230 InsertNewInstBefore(Cast, *Caller);
3231 Args.push_back(Cast);
3233 Args.push_back(*AI);
3238 if (FT->getReturnType() == Type::VoidTy)
3239 Caller->setName(""); // Void type should not have a name...
3242 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
3243 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
3244 Args, Caller->getName(), Caller);
3246 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
3249 // Insert a cast of the return type as necessary...
3251 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
3252 if (NV->getType() != Type::VoidTy) {
3253 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
3255 // If this is an invoke instruction, we should insert it after the first
3256 // non-phi, instruction in the normal successor block.
3257 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
3258 BasicBlock::iterator I = II->getNormalDest()->begin();
3259 while (isa<PHINode>(I)) ++I;
3260 InsertNewInstBefore(NC, *I);
3262 // Otherwise, it's a call, just insert cast right after the call instr
3263 InsertNewInstBefore(NC, *Caller);
3265 AddUsersToWorkList(*Caller);
3267 NV = Constant::getNullValue(Caller->getType());
3271 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
3272 Caller->replaceAllUsesWith(NV);
3273 Caller->getParent()->getInstList().erase(Caller);
3274 removeFromWorkList(Caller);
3280 // PHINode simplification
3282 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
3283 if (Value *V = hasConstantValue(&PN))
3284 return ReplaceInstUsesWith(PN, V);
3286 // If the only user of this instruction is a cast instruction, and all of the
3287 // incoming values are constants, change this PHI to merge together the casted
3290 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
3291 if (CI->getType() != PN.getType()) { // noop casts will be folded
3292 bool AllConstant = true;
3293 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
3294 if (!isa<Constant>(PN.getIncomingValue(i))) {
3295 AllConstant = false;
3299 // Make a new PHI with all casted values.
3300 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
3301 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
3302 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
3303 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
3304 PN.getIncomingBlock(i));
3307 // Update the cast instruction.
3308 CI->setOperand(0, New);
3309 WorkList.push_back(CI); // revisit the cast instruction to fold.
3310 WorkList.push_back(New); // Make sure to revisit the new Phi
3311 return &PN; // PN is now dead!
3317 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
3318 Instruction *InsertPoint,
3320 unsigned PS = IC->getTargetData().getPointerSize();
3321 const Type *VTy = V->getType();
3323 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
3324 // We must insert a cast to ensure we sign-extend.
3325 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
3326 V->getName()), *InsertPoint);
3327 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
3332 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
3333 Value *PtrOp = GEP.getOperand(0);
3334 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
3335 // If so, eliminate the noop.
3336 if (GEP.getNumOperands() == 1)
3337 return ReplaceInstUsesWith(GEP, PtrOp);
3339 bool HasZeroPointerIndex = false;
3340 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
3341 HasZeroPointerIndex = C->isNullValue();
3343 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
3344 return ReplaceInstUsesWith(GEP, PtrOp);
3346 // Eliminate unneeded casts for indices.
3347 bool MadeChange = false;
3348 gep_type_iterator GTI = gep_type_begin(GEP);
3349 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
3350 if (isa<SequentialType>(*GTI)) {
3351 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
3352 Value *Src = CI->getOperand(0);
3353 const Type *SrcTy = Src->getType();
3354 const Type *DestTy = CI->getType();
3355 if (Src->getType()->isInteger()) {
3356 if (SrcTy->getPrimitiveSize() == DestTy->getPrimitiveSize()) {
3357 // We can always eliminate a cast from ulong or long to the other.
3358 // We can always eliminate a cast from uint to int or the other on
3359 // 32-bit pointer platforms.
3360 if (DestTy->getPrimitiveSize() >= TD->getPointerSize()) {
3362 GEP.setOperand(i, Src);
3364 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
3365 SrcTy->getPrimitiveSize() == 4) {
3366 // We can always eliminate a cast from int to [u]long. We can
3367 // eliminate a cast from uint to [u]long iff the target is a 32-bit
3369 if (SrcTy->isSigned() ||
3370 SrcTy->getPrimitiveSize() >= TD->getPointerSize()) {
3372 GEP.setOperand(i, Src);
3377 // If we are using a wider index than needed for this platform, shrink it
3378 // to what we need. If the incoming value needs a cast instruction,
3379 // insert it. This explicit cast can make subsequent optimizations more
3381 Value *Op = GEP.getOperand(i);
3382 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
3383 if (Constant *C = dyn_cast<Constant>(Op)) {
3384 GEP.setOperand(i, ConstantExpr::getCast(C,
3385 TD->getIntPtrType()->getSignedVersion()));
3388 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
3389 Op->getName()), GEP);
3390 GEP.setOperand(i, Op);
3394 // If this is a constant idx, make sure to canonicalize it to be a signed
3395 // operand, otherwise CSE and other optimizations are pessimized.
3396 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
3397 GEP.setOperand(i, ConstantExpr::getCast(CUI,
3398 CUI->getType()->getSignedVersion()));
3402 if (MadeChange) return &GEP;
3404 // Combine Indices - If the source pointer to this getelementptr instruction
3405 // is a getelementptr instruction, combine the indices of the two
3406 // getelementptr instructions into a single instruction.
3408 std::vector<Value*> SrcGEPOperands;
3409 if (GetElementPtrInst *Src = dyn_cast<GetElementPtrInst>(PtrOp)) {
3410 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
3411 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(PtrOp)) {
3412 if (CE->getOpcode() == Instruction::GetElementPtr)
3413 SrcGEPOperands.assign(CE->op_begin(), CE->op_end());
3416 if (!SrcGEPOperands.empty()) {
3417 // Note that if our source is a gep chain itself that we wait for that
3418 // chain to be resolved before we perform this transformation. This
3419 // avoids us creating a TON of code in some cases.
3421 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
3422 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
3423 return 0; // Wait until our source is folded to completion.
3425 std::vector<Value *> Indices;
3427 // Find out whether the last index in the source GEP is a sequential idx.
3428 bool EndsWithSequential = false;
3429 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
3430 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
3431 EndsWithSequential = !isa<StructType>(*I);
3433 // Can we combine the two pointer arithmetics offsets?
3434 if (EndsWithSequential) {
3435 // Replace: gep (gep %P, long B), long A, ...
3436 // With: T = long A+B; gep %P, T, ...
3438 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
3439 if (SO1 == Constant::getNullValue(SO1->getType())) {
3441 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
3444 // If they aren't the same type, convert both to an integer of the
3445 // target's pointer size.
3446 if (SO1->getType() != GO1->getType()) {
3447 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
3448 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
3449 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
3450 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
3452 unsigned PS = TD->getPointerSize();
3454 if (SO1->getType()->getPrimitiveSize() == PS) {
3455 // Convert GO1 to SO1's type.
3456 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
3458 } else if (GO1->getType()->getPrimitiveSize() == PS) {
3459 // Convert SO1 to GO1's type.
3460 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
3462 const Type *PT = TD->getIntPtrType();
3463 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
3464 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
3468 if (isa<Constant>(SO1) && isa<Constant>(GO1))
3469 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
3471 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
3472 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
3476 // Recycle the GEP we already have if possible.
3477 if (SrcGEPOperands.size() == 2) {
3478 GEP.setOperand(0, SrcGEPOperands[0]);
3479 GEP.setOperand(1, Sum);
3482 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
3483 SrcGEPOperands.end()-1);
3484 Indices.push_back(Sum);
3485 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
3487 } else if (isa<Constant>(*GEP.idx_begin()) &&
3488 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
3489 SrcGEPOperands.size() != 1) {
3490 // Otherwise we can do the fold if the first index of the GEP is a zero
3491 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
3492 SrcGEPOperands.end());
3493 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
3496 if (!Indices.empty())
3497 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
3499 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
3500 // GEP of global variable. If all of the indices for this GEP are
3501 // constants, we can promote this to a constexpr instead of an instruction.
3503 // Scan for nonconstants...
3504 std::vector<Constant*> Indices;
3505 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
3506 for (; I != E && isa<Constant>(*I); ++I)
3507 Indices.push_back(cast<Constant>(*I));
3509 if (I == E) { // If they are all constants...
3510 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
3512 // Replace all uses of the GEP with the new constexpr...
3513 return ReplaceInstUsesWith(GEP, CE);
3515 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(PtrOp)) {
3516 if (CE->getOpcode() == Instruction::Cast) {
3517 if (HasZeroPointerIndex) {
3518 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
3519 // into : GEP [10 x ubyte]* X, long 0, ...
3521 // This occurs when the program declares an array extern like "int X[];"
3523 Constant *X = CE->getOperand(0);
3524 const PointerType *CPTy = cast<PointerType>(CE->getType());
3525 if (const PointerType *XTy = dyn_cast<PointerType>(X->getType()))
3526 if (const ArrayType *XATy =
3527 dyn_cast<ArrayType>(XTy->getElementType()))
3528 if (const ArrayType *CATy =
3529 dyn_cast<ArrayType>(CPTy->getElementType()))
3530 if (CATy->getElementType() == XATy->getElementType()) {
3531 // At this point, we know that the cast source type is a pointer
3532 // to an array of the same type as the destination pointer
3533 // array. Because the array type is never stepped over (there
3534 // is a leading zero) we can fold the cast into this GEP.
3535 GEP.setOperand(0, X);
3545 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
3546 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
3547 if (AI.isArrayAllocation()) // Check C != 1
3548 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
3549 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
3550 AllocationInst *New = 0;
3552 // Create and insert the replacement instruction...
3553 if (isa<MallocInst>(AI))
3554 New = new MallocInst(NewTy, 0, AI.getName());
3556 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
3557 New = new AllocaInst(NewTy, 0, AI.getName());
3560 InsertNewInstBefore(New, AI);
3562 // Scan to the end of the allocation instructions, to skip over a block of
3563 // allocas if possible...
3565 BasicBlock::iterator It = New;
3566 while (isa<AllocationInst>(*It)) ++It;
3568 // Now that I is pointing to the first non-allocation-inst in the block,
3569 // insert our getelementptr instruction...
3571 std::vector<Value*> Idx(2, Constant::getNullValue(Type::IntTy));
3572 Value *V = new GetElementPtrInst(New, Idx, New->getName()+".sub", It);
3574 // Now make everything use the getelementptr instead of the original
3576 return ReplaceInstUsesWith(AI, V);
3579 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
3580 // Note that we only do this for alloca's, because malloc should allocate and
3581 // return a unique pointer, even for a zero byte allocation.
3582 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
3583 TD->getTypeSize(AI.getAllocatedType()) == 0)
3584 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
3589 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
3590 Value *Op = FI.getOperand(0);
3592 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
3593 if (CastInst *CI = dyn_cast<CastInst>(Op))
3594 if (isa<PointerType>(CI->getOperand(0)->getType())) {
3595 FI.setOperand(0, CI->getOperand(0));
3599 // If we have 'free null' delete the instruction. This can happen in stl code
3600 // when lots of inlining happens.
3601 if (isa<ConstantPointerNull>(Op))
3602 return EraseInstFromFunction(FI);
3608 /// GetGEPGlobalInitializer - Given a constant, and a getelementptr
3609 /// constantexpr, return the constant value being addressed by the constant
3610 /// expression, or null if something is funny.
3612 static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
3613 if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
3614 return 0; // Do not allow stepping over the value!
3616 // Loop over all of the operands, tracking down which value we are
3618 gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
3619 for (++I; I != E; ++I)
3620 if (const StructType *STy = dyn_cast<StructType>(*I)) {
3621 ConstantUInt *CU = cast<ConstantUInt>(I.getOperand());
3622 assert(CU->getValue() < STy->getNumElements() &&
3623 "Struct index out of range!");
3624 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
3625 C = CS->getOperand(CU->getValue());
3626 } else if (isa<ConstantAggregateZero>(C)) {
3627 C = Constant::getNullValue(STy->getElementType(CU->getValue()));
3631 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
3632 const ArrayType *ATy = cast<ArrayType>(*I);
3633 if ((uint64_t)CI->getRawValue() >= ATy->getNumElements()) return 0;
3634 if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
3635 C = CA->getOperand(CI->getRawValue());
3636 else if (isa<ConstantAggregateZero>(C))
3637 C = Constant::getNullValue(ATy->getElementType());
3646 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
3647 User *CI = cast<User>(LI.getOperand(0));
3649 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
3650 if (const PointerType *SrcTy =
3651 dyn_cast<PointerType>(CI->getOperand(0)->getType())) {
3652 const Type *SrcPTy = SrcTy->getElementType();
3653 if (SrcPTy->isSized() && DestPTy->isSized() &&
3654 IC.getTargetData().getTypeSize(SrcPTy) ==
3655 IC.getTargetData().getTypeSize(DestPTy) &&
3656 (SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
3657 (DestPTy->isInteger() || isa<PointerType>(DestPTy))) {
3658 // Okay, we are casting from one integer or pointer type to another of
3659 // the same size. Instead of casting the pointer before the load, cast
3660 // the result of the loaded value.
3661 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CI->getOperand(0),
3663 LI.isVolatile()),LI);
3664 // Now cast the result of the load.
3665 return new CastInst(NewLoad, LI.getType());
3671 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
3672 /// from this value cannot trap. If it is not obviously safe to load from the
3673 /// specified pointer, we do a quick local scan of the basic block containing
3674 /// ScanFrom, to determine if the address is already accessed.
3675 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
3676 // If it is an alloca or global variable, it is always safe to load from.
3677 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
3679 // Otherwise, be a little bit agressive by scanning the local block where we
3680 // want to check to see if the pointer is already being loaded or stored
3681 // from/to. If so, the previous load or store would have already trapped,
3682 // so there is no harm doing an extra load (also, CSE will later eliminate
3683 // the load entirely).
3684 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
3689 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
3690 if (LI->getOperand(0) == V) return true;
3691 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
3692 if (SI->getOperand(1) == V) return true;
3698 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
3699 Value *Op = LI.getOperand(0);
3701 if (Constant *C = dyn_cast<Constant>(Op))
3702 if (C->isNullValue() && !LI.isVolatile()) // load null -> 0
3703 return ReplaceInstUsesWith(LI, Constant::getNullValue(LI.getType()));
3705 // Instcombine load (constant global) into the value loaded...
3706 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
3707 if (GV->isConstant() && !GV->isExternal())
3708 return ReplaceInstUsesWith(LI, GV->getInitializer());
3710 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded...
3711 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
3712 if (CE->getOpcode() == Instruction::GetElementPtr) {
3713 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
3714 if (GV->isConstant() && !GV->isExternal())
3715 if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
3716 return ReplaceInstUsesWith(LI, V);
3717 } else if (CE->getOpcode() == Instruction::Cast) {
3718 if (Instruction *Res = InstCombineLoadCast(*this, LI))
3722 // load (cast X) --> cast (load X) iff safe
3723 if (CastInst *CI = dyn_cast<CastInst>(Op))
3724 if (Instruction *Res = InstCombineLoadCast(*this, LI))
3727 if (!LI.isVolatile() && Op->hasOneUse()) {
3728 // Change select and PHI nodes to select values instead of addresses: this
3729 // helps alias analysis out a lot, allows many others simplifications, and
3730 // exposes redundancy in the code.
3732 // Note that we cannot do the transformation unless we know that the
3733 // introduced loads cannot trap! Something like this is valid as long as
3734 // the condition is always false: load (select bool %C, int* null, int* %G),
3735 // but it would not be valid if we transformed it to load from null
3738 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
3739 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
3740 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
3741 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
3742 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
3743 SI->getOperand(1)->getName()+".val"), LI);
3744 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
3745 SI->getOperand(2)->getName()+".val"), LI);
3746 return new SelectInst(SI->getCondition(), V1, V2);
3749 // load (select (cond, null, P)) -> load P
3750 if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
3751 if (C->isNullValue()) {
3752 LI.setOperand(0, SI->getOperand(2));
3756 // load (select (cond, P, null)) -> load P
3757 if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
3758 if (C->isNullValue()) {
3759 LI.setOperand(0, SI->getOperand(1));
3763 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
3764 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
3765 bool Safe = PN->getParent() == LI.getParent();
3767 // Scan all of the instructions between the PHI and the load to make
3768 // sure there are no instructions that might possibly alter the value
3769 // loaded from the PHI.
3771 BasicBlock::iterator I = &LI;
3772 for (--I; !isa<PHINode>(I); --I)
3773 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
3779 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
3780 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
3781 PN->getIncomingBlock(i)->getTerminator()))
3786 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
3787 InsertNewInstBefore(NewPN, *PN);
3788 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
3790 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
3791 BasicBlock *BB = PN->getIncomingBlock(i);
3792 Value *&TheLoad = LoadMap[BB];
3794 Value *InVal = PN->getIncomingValue(i);
3795 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
3796 InVal->getName()+".val"),
3797 *BB->getTerminator());
3799 NewPN->addIncoming(TheLoad, BB);
3801 return ReplaceInstUsesWith(LI, NewPN);
3809 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
3810 // Change br (not X), label True, label False to: br X, label False, True
3812 BasicBlock *TrueDest;
3813 BasicBlock *FalseDest;
3814 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
3815 !isa<Constant>(X)) {
3816 // Swap Destinations and condition...
3818 BI.setSuccessor(0, FalseDest);
3819 BI.setSuccessor(1, TrueDest);
3823 // Cannonicalize setne -> seteq
3824 Instruction::BinaryOps Op; Value *Y;
3825 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
3826 TrueDest, FalseDest)))
3827 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
3828 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
3829 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
3830 std::string Name = I->getName(); I->setName("");
3831 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
3832 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
3833 // Swap Destinations and condition...
3834 BI.setCondition(NewSCC);
3835 BI.setSuccessor(0, FalseDest);
3836 BI.setSuccessor(1, TrueDest);
3837 removeFromWorkList(I);
3838 I->getParent()->getInstList().erase(I);
3839 WorkList.push_back(cast<Instruction>(NewSCC));
3846 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
3847 Value *Cond = SI.getCondition();
3848 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
3849 if (I->getOpcode() == Instruction::Add)
3850 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
3851 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
3852 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
3853 SI.setOperand(i, ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
3855 SI.setOperand(0, I->getOperand(0));
3856 WorkList.push_back(I);
3864 void InstCombiner::removeFromWorkList(Instruction *I) {
3865 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
3869 bool InstCombiner::runOnFunction(Function &F) {
3870 bool Changed = false;
3871 TD = &getAnalysis<TargetData>();
3873 for (inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i)
3874 WorkList.push_back(&*i);
3877 while (!WorkList.empty()) {
3878 Instruction *I = WorkList.back(); // Get an instruction from the worklist
3879 WorkList.pop_back();
3881 // Check to see if we can DCE or ConstantPropagate the instruction...
3882 // Check to see if we can DIE the instruction...
3883 if (isInstructionTriviallyDead(I)) {
3884 // Add operands to the worklist...
3885 if (I->getNumOperands() < 4)
3886 AddUsesToWorkList(*I);
3889 I->getParent()->getInstList().erase(I);
3890 removeFromWorkList(I);
3894 // Instruction isn't dead, see if we can constant propagate it...
3895 if (Constant *C = ConstantFoldInstruction(I)) {
3896 // Add operands to the worklist...
3897 AddUsesToWorkList(*I);
3898 ReplaceInstUsesWith(*I, C);
3901 I->getParent()->getInstList().erase(I);
3902 removeFromWorkList(I);
3906 // Now that we have an instruction, try combining it to simplify it...
3907 if (Instruction *Result = visit(*I)) {
3909 // Should we replace the old instruction with a new one?
3911 DEBUG(std::cerr << "IC: Old = " << *I
3912 << " New = " << *Result);
3914 // Everything uses the new instruction now.
3915 I->replaceAllUsesWith(Result);
3917 // Push the new instruction and any users onto the worklist.
3918 WorkList.push_back(Result);
3919 AddUsersToWorkList(*Result);
3921 // Move the name to the new instruction first...
3922 std::string OldName = I->getName(); I->setName("");
3923 Result->setName(OldName);
3925 // Insert the new instruction into the basic block...
3926 BasicBlock *InstParent = I->getParent();
3927 InstParent->getInstList().insert(I, Result);
3929 // Make sure that we reprocess all operands now that we reduced their
3931 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
3932 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
3933 WorkList.push_back(OpI);
3935 // Instructions can end up on the worklist more than once. Make sure
3936 // we do not process an instruction that has been deleted.
3937 removeFromWorkList(I);
3939 // Erase the old instruction.
3940 InstParent->getInstList().erase(I);
3942 DEBUG(std::cerr << "IC: MOD = " << *I);
3944 // If the instruction was modified, it's possible that it is now dead.
3945 // if so, remove it.
3946 if (isInstructionTriviallyDead(I)) {
3947 // Make sure we process all operands now that we are reducing their
3949 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
3950 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
3951 WorkList.push_back(OpI);
3953 // Instructions may end up in the worklist more than once. Erase all
3954 // occurrances of this instruction.
3955 removeFromWorkList(I);
3956 I->getParent()->getInstList().erase(I);
3958 WorkList.push_back(Result);
3959 AddUsersToWorkList(*Result);
3969 FunctionPass *llvm::createInstructionCombiningPass() {
3970 return new InstCombiner();