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 "Support/Debug.h"
52 #include "Support/Statistic.h"
57 Statistic<> NumCombined ("instcombine", "Number of insts combined");
58 Statistic<> NumConstProp("instcombine", "Number of constant folds");
59 Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
61 class InstCombiner : public FunctionPass,
62 public InstVisitor<InstCombiner, Instruction*> {
63 // Worklist of all of the instructions that need to be simplified.
64 std::vector<Instruction*> WorkList;
67 /// AddUsersToWorkList - When an instruction is simplified, add all users of
68 /// the instruction to the work lists because they might get more simplified
71 void AddUsersToWorkList(Instruction &I) {
72 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
74 WorkList.push_back(cast<Instruction>(*UI));
77 /// AddUsesToWorkList - When an instruction is simplified, add operands to
78 /// the work lists because they might get more simplified now.
80 void AddUsesToWorkList(Instruction &I) {
81 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
82 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
83 WorkList.push_back(Op);
86 // removeFromWorkList - remove all instances of I from the worklist.
87 void removeFromWorkList(Instruction *I);
89 virtual bool runOnFunction(Function &F);
91 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
92 AU.addRequired<TargetData>();
96 TargetData &getTargetData() const { return *TD; }
98 // Visitation implementation - Implement instruction combining for different
99 // instruction types. The semantics are as follows:
101 // null - No change was made
102 // I - Change was made, I is still valid, I may be dead though
103 // otherwise - Change was made, replace I with returned instruction
105 Instruction *visitAdd(BinaryOperator &I);
106 Instruction *visitSub(BinaryOperator &I);
107 Instruction *visitMul(BinaryOperator &I);
108 Instruction *visitDiv(BinaryOperator &I);
109 Instruction *visitRem(BinaryOperator &I);
110 Instruction *visitAnd(BinaryOperator &I);
111 Instruction *visitOr (BinaryOperator &I);
112 Instruction *visitXor(BinaryOperator &I);
113 Instruction *visitSetCondInst(BinaryOperator &I);
114 Instruction *visitShiftInst(ShiftInst &I);
115 Instruction *visitCastInst(CastInst &CI);
116 Instruction *visitSelectInst(SelectInst &CI);
117 Instruction *visitCallInst(CallInst &CI);
118 Instruction *visitInvokeInst(InvokeInst &II);
119 Instruction *visitPHINode(PHINode &PN);
120 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
121 Instruction *visitAllocationInst(AllocationInst &AI);
122 Instruction *visitFreeInst(FreeInst &FI);
123 Instruction *visitLoadInst(LoadInst &LI);
124 Instruction *visitBranchInst(BranchInst &BI);
126 // visitInstruction - Specify what to return for unhandled instructions...
127 Instruction *visitInstruction(Instruction &I) { return 0; }
130 Instruction *visitCallSite(CallSite CS);
131 bool transformConstExprCastCall(CallSite CS);
134 // InsertNewInstBefore - insert an instruction New before instruction Old
135 // in the program. Add the new instruction to the worklist.
137 Value *InsertNewInstBefore(Instruction *New, Instruction &Old) {
138 assert(New && New->getParent() == 0 &&
139 "New instruction already inserted into a basic block!");
140 BasicBlock *BB = Old.getParent();
141 BB->getInstList().insert(&Old, New); // Insert inst
142 WorkList.push_back(New); // Add to worklist
146 // ReplaceInstUsesWith - This method is to be used when an instruction is
147 // found to be dead, replacable with another preexisting expression. Here
148 // we add all uses of I to the worklist, replace all uses of I with the new
149 // value, then return I, so that the inst combiner will know that I was
152 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
153 AddUsersToWorkList(I); // Add all modified instrs to worklist
155 I.replaceAllUsesWith(V);
158 // If we are replacing the instruction with itself, this must be in a
159 // segment of unreachable code, so just clobber the instruction.
160 I.replaceAllUsesWith(Constant::getNullValue(I.getType()));
165 // EraseInstFromFunction - When dealing with an instruction that has side
166 // effects or produces a void value, we can't rely on DCE to delete the
167 // instruction. Instead, visit methods should return the value returned by
169 Instruction *EraseInstFromFunction(Instruction &I) {
170 assert(I.use_empty() && "Cannot erase instruction that is used!");
171 AddUsesToWorkList(I);
172 removeFromWorkList(&I);
173 I.getParent()->getInstList().erase(&I);
174 return 0; // Don't do anything with FI
179 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
180 /// InsertBefore instruction. This is specialized a bit to avoid inserting
181 /// casts that are known to not do anything...
183 Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
184 Instruction *InsertBefore);
186 // SimplifyCommutative - This performs a few simplifications for commutative
188 bool SimplifyCommutative(BinaryOperator &I);
190 Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
191 ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
194 RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
197 // getComplexity: Assign a complexity or rank value to LLVM Values...
198 // 0 -> Constant, 1 -> Other, 2 -> Argument, 2 -> Unary, 3 -> OtherInst
199 static unsigned getComplexity(Value *V) {
200 if (isa<Instruction>(V)) {
201 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
205 if (isa<Argument>(V)) return 2;
206 return isa<Constant>(V) ? 0 : 1;
209 // isOnlyUse - Return true if this instruction will be deleted if we stop using
211 static bool isOnlyUse(Value *V) {
212 return V->hasOneUse() || isa<Constant>(V);
215 // getSignedIntegralType - Given an unsigned integral type, return the signed
216 // version of it that has the same size.
217 static const Type *getSignedIntegralType(const Type *Ty) {
218 switch (Ty->getPrimitiveID()) {
219 default: assert(0 && "Invalid unsigned integer type!"); abort();
220 case Type::UByteTyID: return Type::SByteTy;
221 case Type::UShortTyID: return Type::ShortTy;
222 case Type::UIntTyID: return Type::IntTy;
223 case Type::ULongTyID: return Type::LongTy;
227 // getUnsignedIntegralType - Given an signed integral type, return the unsigned
228 // version of it that has the same size.
229 static const Type *getUnsignedIntegralType(const Type *Ty) {
230 switch (Ty->getPrimitiveID()) {
231 default: assert(0 && "Invalid signed integer type!"); abort();
232 case Type::SByteTyID: return Type::UByteTy;
233 case Type::ShortTyID: return Type::UShortTy;
234 case Type::IntTyID: return Type::UIntTy;
235 case Type::LongTyID: return Type::ULongTy;
239 // getPromotedType - Return the specified type promoted as it would be to pass
240 // though a va_arg area...
241 static const Type *getPromotedType(const Type *Ty) {
242 switch (Ty->getPrimitiveID()) {
243 case Type::SByteTyID:
244 case Type::ShortTyID: return Type::IntTy;
245 case Type::UByteTyID:
246 case Type::UShortTyID: return Type::UIntTy;
247 case Type::FloatTyID: return Type::DoubleTy;
252 // SimplifyCommutative - This performs a few simplifications for commutative
255 // 1. Order operands such that they are listed from right (least complex) to
256 // left (most complex). This puts constants before unary operators before
259 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
260 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
262 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
263 bool Changed = false;
264 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
265 Changed = !I.swapOperands();
267 if (!I.isAssociative()) return Changed;
268 Instruction::BinaryOps Opcode = I.getOpcode();
269 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
270 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
271 if (isa<Constant>(I.getOperand(1))) {
272 Constant *Folded = ConstantExpr::get(I.getOpcode(),
273 cast<Constant>(I.getOperand(1)),
274 cast<Constant>(Op->getOperand(1)));
275 I.setOperand(0, Op->getOperand(0));
276 I.setOperand(1, Folded);
278 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
279 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
280 isOnlyUse(Op) && isOnlyUse(Op1)) {
281 Constant *C1 = cast<Constant>(Op->getOperand(1));
282 Constant *C2 = cast<Constant>(Op1->getOperand(1));
284 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
285 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
286 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
289 WorkList.push_back(New);
290 I.setOperand(0, New);
291 I.setOperand(1, Folded);
298 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
299 // if the LHS is a constant zero (which is the 'negate' form).
301 static inline Value *dyn_castNegVal(Value *V) {
302 if (BinaryOperator::isNeg(V))
303 return BinaryOperator::getNegArgument(cast<BinaryOperator>(V));
305 // Constants can be considered to be negated values if they can be folded...
306 if (Constant *C = dyn_cast<Constant>(V))
307 return ConstantExpr::get(Instruction::Sub,
308 Constant::getNullValue(V->getType()), C);
312 static Constant *NotConstant(Constant *C) {
313 return ConstantExpr::get(Instruction::Xor, C,
314 ConstantIntegral::getAllOnesValue(C->getType()));
317 static inline Value *dyn_castNotVal(Value *V) {
318 if (BinaryOperator::isNot(V))
319 return BinaryOperator::getNotArgument(cast<BinaryOperator>(V));
321 // Constants can be considered to be not'ed values...
322 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
323 return NotConstant(C);
327 // dyn_castFoldableMul - If this value is a multiply that can be folded into
328 // other computations (because it has a constant operand), return the
329 // non-constant operand of the multiply.
331 static inline Value *dyn_castFoldableMul(Value *V) {
332 if (V->hasOneUse() && V->getType()->isInteger())
333 if (Instruction *I = dyn_cast<Instruction>(V))
334 if (I->getOpcode() == Instruction::Mul)
335 if (isa<Constant>(I->getOperand(1)))
336 return I->getOperand(0);
340 // dyn_castMaskingAnd - If this value is an And instruction masking a value with
341 // a constant, return the constant being anded with.
343 template<class ValueType>
344 static inline Constant *dyn_castMaskingAnd(ValueType *V) {
345 if (Instruction *I = dyn_cast<Instruction>(V))
346 if (I->getOpcode() == Instruction::And)
347 return dyn_cast<Constant>(I->getOperand(1));
349 // If this is a constant, it acts just like we were masking with it.
350 return dyn_cast<Constant>(V);
353 // Log2 - Calculate the log base 2 for the specified value if it is exactly a
355 static unsigned Log2(uint64_t Val) {
356 assert(Val > 1 && "Values 0 and 1 should be handled elsewhere!");
359 if (Val & 1) return 0; // Multiple bits set?
367 /// AssociativeOpt - Perform an optimization on an associative operator. This
368 /// function is designed to check a chain of associative operators for a
369 /// potential to apply a certain optimization. Since the optimization may be
370 /// applicable if the expression was reassociated, this checks the chain, then
371 /// reassociates the expression as necessary to expose the optimization
372 /// opportunity. This makes use of a special Functor, which must define
373 /// 'shouldApply' and 'apply' methods.
375 template<typename Functor>
376 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
377 unsigned Opcode = Root.getOpcode();
378 Value *LHS = Root.getOperand(0);
380 // Quick check, see if the immediate LHS matches...
381 if (F.shouldApply(LHS))
382 return F.apply(Root);
384 // Otherwise, if the LHS is not of the same opcode as the root, return.
385 Instruction *LHSI = dyn_cast<Instruction>(LHS);
386 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
387 // Should we apply this transform to the RHS?
388 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
390 // If not to the RHS, check to see if we should apply to the LHS...
391 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
392 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
396 // If the functor wants to apply the optimization to the RHS of LHSI,
397 // reassociate the expression from ((? op A) op B) to (? op (A op B))
399 BasicBlock *BB = Root.getParent();
400 // All of the instructions have a single use and have no side-effects,
401 // because of this, we can pull them all into the current basic block.
402 if (LHSI->getParent() != BB) {
403 // Move all of the instructions from root to LHSI into the current
405 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
406 Instruction *LastUse = &Root;
407 while (TmpLHSI->getParent() == BB) {
409 TmpLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
412 // Loop over all of the instructions in other blocks, moving them into
414 Value *TmpLHS = TmpLHSI;
416 TmpLHSI = cast<Instruction>(TmpLHS);
417 // Remove from current block...
418 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
419 // Insert before the last instruction...
420 BB->getInstList().insert(LastUse, TmpLHSI);
421 TmpLHS = TmpLHSI->getOperand(0);
422 } while (TmpLHSI != LHSI);
425 // Now all of the instructions are in the current basic block, go ahead
426 // and perform the reassociation.
427 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
429 // First move the selected RHS to the LHS of the root...
430 Root.setOperand(0, LHSI->getOperand(1));
432 // Make what used to be the LHS of the root be the user of the root...
433 Value *ExtraOperand = TmpLHSI->getOperand(1);
434 if (&Root != TmpLHSI)
435 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
437 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
440 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
441 BB->getInstList().remove(&Root); // Remove root from the BB
442 BB->getInstList().insert(TmpLHSI, &Root); // Insert root before TmpLHSI
444 // Now propagate the ExtraOperand down the chain of instructions until we
446 while (TmpLHSI != LHSI) {
447 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
448 Value *NextOp = NextLHSI->getOperand(1);
449 NextLHSI->setOperand(1, ExtraOperand);
451 ExtraOperand = NextOp;
454 // Now that the instructions are reassociated, have the functor perform
455 // the transformation...
456 return F.apply(Root);
459 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
465 // AddRHS - Implements: X + X --> X << 1
468 AddRHS(Value *rhs) : RHS(rhs) {}
469 bool shouldApply(Value *LHS) const { return LHS == RHS; }
470 Instruction *apply(BinaryOperator &Add) const {
471 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
472 ConstantInt::get(Type::UByteTy, 1));
476 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
478 struct AddMaskingAnd {
480 AddMaskingAnd(Constant *c) : C2(c) {}
481 bool shouldApply(Value *LHS) const {
482 if (Constant *C1 = dyn_castMaskingAnd(LHS))
483 return ConstantExpr::get(Instruction::And, C1, C2)->isNullValue();
486 Instruction *apply(BinaryOperator &Add) const {
487 return BinaryOperator::create(Instruction::Or, Add.getOperand(0),
492 static Value *FoldOperationIntoSelectOperand(Instruction &BI, Value *SO,
494 // Figure out if the constant is the left or the right argument.
495 bool ConstIsRHS = isa<Constant>(BI.getOperand(1));
496 Constant *ConstOperand = cast<Constant>(BI.getOperand(ConstIsRHS));
498 if (Constant *SOC = dyn_cast<Constant>(SO)) {
500 return ConstantExpr::get(BI.getOpcode(), SOC, ConstOperand);
501 return ConstantExpr::get(BI.getOpcode(), ConstOperand, SOC);
504 Value *Op0 = SO, *Op1 = ConstOperand;
508 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&BI))
509 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1);
510 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&BI))
511 New = new ShiftInst(SI->getOpcode(), Op0, Op1);
513 assert(0 && "Unknown binary instruction type!");
514 return IC->InsertNewInstBefore(New, BI);
517 // FoldBinOpIntoSelect - Given an instruction with a select as one operand and a
518 // constant as the other operand, try to fold the binary operator into the
520 static Instruction *FoldBinOpIntoSelect(Instruction &BI, SelectInst *SI,
522 // Don't modify shared select instructions
523 if (!SI->hasOneUse()) return 0;
524 Value *TV = SI->getOperand(1);
525 Value *FV = SI->getOperand(2);
527 if (isa<Constant>(TV) || isa<Constant>(FV)) {
528 Value *SelectTrueVal = FoldOperationIntoSelectOperand(BI, TV, IC);
529 Value *SelectFalseVal = FoldOperationIntoSelectOperand(BI, FV, IC);
531 return new SelectInst(SI->getCondition(), SelectTrueVal,
537 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
538 bool Changed = SimplifyCommutative(I);
539 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
542 if (!I.getType()->isFloatingPoint() && // -0 + +0 = +0, so it's not a noop
543 RHS == Constant::getNullValue(I.getType()))
544 return ReplaceInstUsesWith(I, LHS);
547 if (I.getType()->isInteger())
548 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
551 if (Value *V = dyn_castNegVal(LHS))
552 return BinaryOperator::create(Instruction::Sub, RHS, V);
555 if (!isa<Constant>(RHS))
556 if (Value *V = dyn_castNegVal(RHS))
557 return BinaryOperator::create(Instruction::Sub, LHS, V);
559 // X*C + X --> X * (C+1)
560 if (dyn_castFoldableMul(LHS) == RHS) {
562 ConstantExpr::get(Instruction::Add,
563 cast<Constant>(cast<Instruction>(LHS)->getOperand(1)),
564 ConstantInt::get(I.getType(), 1));
565 return BinaryOperator::create(Instruction::Mul, RHS, CP1);
568 // X + X*C --> X * (C+1)
569 if (dyn_castFoldableMul(RHS) == LHS) {
571 ConstantExpr::get(Instruction::Add,
572 cast<Constant>(cast<Instruction>(RHS)->getOperand(1)),
573 ConstantInt::get(I.getType(), 1));
574 return BinaryOperator::create(Instruction::Mul, LHS, CP1);
577 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
578 if (Constant *C2 = dyn_castMaskingAnd(RHS))
579 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
581 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
582 if (Instruction *ILHS = dyn_cast<Instruction>(LHS)) {
583 switch (ILHS->getOpcode()) {
584 case Instruction::Xor:
585 // ~X + C --> (C-1) - X
586 if (ConstantInt *XorRHS = dyn_cast<ConstantInt>(ILHS->getOperand(1)))
587 if (XorRHS->isAllOnesValue())
588 return BinaryOperator::create(Instruction::Sub,
589 ConstantExpr::get(Instruction::Sub,
590 CRHS, ConstantInt::get(I.getType(), 1)),
591 ILHS->getOperand(0));
593 case Instruction::Select:
594 // Try to fold constant add into select arguments.
595 if (Instruction *R = FoldBinOpIntoSelect(I,cast<SelectInst>(ILHS),this))
603 return Changed ? &I : 0;
606 // isSignBit - Return true if the value represented by the constant only has the
607 // highest order bit set.
608 static bool isSignBit(ConstantInt *CI) {
609 unsigned NumBits = CI->getType()->getPrimitiveSize()*8;
610 return (CI->getRawValue() & ~(-1LL << NumBits)) == (1ULL << (NumBits-1));
613 static unsigned getTypeSizeInBits(const Type *Ty) {
614 return Ty == Type::BoolTy ? 1 : Ty->getPrimitiveSize()*8;
617 /// RemoveNoopCast - Strip off nonconverting casts from the value.
619 static Value *RemoveNoopCast(Value *V) {
620 if (CastInst *CI = dyn_cast<CastInst>(V)) {
621 const Type *CTy = CI->getType();
622 const Type *OpTy = CI->getOperand(0)->getType();
623 if (CTy->isInteger() && OpTy->isInteger()) {
624 if (CTy->getPrimitiveSize() == OpTy->getPrimitiveSize())
625 return RemoveNoopCast(CI->getOperand(0));
626 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
627 return RemoveNoopCast(CI->getOperand(0));
632 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
633 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
635 if (Op0 == Op1) // sub X, X -> 0
636 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
638 // If this is a 'B = x-(-A)', change to B = x+A...
639 if (Value *V = dyn_castNegVal(Op1))
640 return BinaryOperator::create(Instruction::Add, Op0, V);
642 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
643 // Replace (-1 - A) with (~A)...
644 if (C->isAllOnesValue())
645 return BinaryOperator::createNot(Op1);
647 // C - ~X == X + (1+C)
648 if (BinaryOperator::isNot(Op1))
649 return BinaryOperator::create(Instruction::Add,
650 BinaryOperator::getNotArgument(cast<BinaryOperator>(Op1)),
651 ConstantExpr::get(Instruction::Add, C,
652 ConstantInt::get(I.getType(), 1)));
653 // -((uint)X >> 31) -> ((int)X >> 31)
654 // -((int)X >> 31) -> ((uint)X >> 31)
655 if (C->isNullValue()) {
656 Value *NoopCastedRHS = RemoveNoopCast(Op1);
657 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
658 if (SI->getOpcode() == Instruction::Shr)
659 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
661 if (SI->getType()->isSigned())
662 NewTy = getUnsignedIntegralType(SI->getType());
664 NewTy = getSignedIntegralType(SI->getType());
665 // Check to see if we are shifting out everything but the sign bit.
666 if (CU->getValue() == SI->getType()->getPrimitiveSize()*8-1) {
667 // Ok, the transformation is safe. Insert a cast of the incoming
668 // value, then the new shift, then the new cast.
669 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
670 SI->getOperand(0)->getName());
671 Value *InV = InsertNewInstBefore(FirstCast, I);
672 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
674 if (NewShift->getType() == I.getType())
677 InV = InsertNewInstBefore(NewShift, I);
678 return new CastInst(NewShift, I.getType());
684 // Try to fold constant sub into select arguments.
685 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
686 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
690 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1))
691 if (Op1I->hasOneUse()) {
692 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
693 // is not used by anyone else...
695 if (Op1I->getOpcode() == Instruction::Sub &&
696 !Op1I->getType()->isFloatingPoint()) {
697 // Swap the two operands of the subexpr...
698 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
699 Op1I->setOperand(0, IIOp1);
700 Op1I->setOperand(1, IIOp0);
702 // Create the new top level add instruction...
703 return BinaryOperator::create(Instruction::Add, Op0, Op1);
706 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
708 if (Op1I->getOpcode() == Instruction::And &&
709 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
710 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
712 Instruction *NewNot = BinaryOperator::createNot(OtherOp, "B.not", &I);
713 return BinaryOperator::create(Instruction::And, Op0, NewNot);
716 // X - X*C --> X * (1-C)
717 if (dyn_castFoldableMul(Op1I) == Op0) {
719 ConstantExpr::get(Instruction::Sub,
720 ConstantInt::get(I.getType(), 1),
721 cast<Constant>(cast<Instruction>(Op1)->getOperand(1)));
722 assert(CP1 && "Couldn't constant fold 1-C?");
723 return BinaryOperator::create(Instruction::Mul, Op0, CP1);
727 // X*C - X --> X * (C-1)
728 if (dyn_castFoldableMul(Op0) == Op1) {
730 ConstantExpr::get(Instruction::Sub,
731 cast<Constant>(cast<Instruction>(Op0)->getOperand(1)),
732 ConstantInt::get(I.getType(), 1));
733 assert(CP1 && "Couldn't constant fold C - 1?");
734 return BinaryOperator::create(Instruction::Mul, Op1, CP1);
740 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
741 /// really just returns true if the most significant (sign) bit is set.
742 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
743 if (RHS->getType()->isSigned()) {
744 // True if source is LHS < 0 or LHS <= -1
745 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
746 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
748 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
749 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
750 // the size of the integer type.
751 if (Opcode == Instruction::SetGE)
752 return RHSC->getValue() == 1ULL<<(RHS->getType()->getPrimitiveSize()*8-1);
753 if (Opcode == Instruction::SetGT)
754 return RHSC->getValue() ==
755 (1ULL << (RHS->getType()->getPrimitiveSize()*8-1))-1;
760 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
761 bool Changed = SimplifyCommutative(I);
762 Value *Op0 = I.getOperand(0);
764 // Simplify mul instructions with a constant RHS...
765 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
766 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
768 // ((X << C1)*C2) == (X * (C2 << C1))
769 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
770 if (SI->getOpcode() == Instruction::Shl)
771 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
772 return BinaryOperator::create(Instruction::Mul, SI->getOperand(0),
773 ConstantExpr::get(Instruction::Shl, CI, ShOp));
775 if (CI->isNullValue())
776 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
777 if (CI->equalsInt(1)) // X * 1 == X
778 return ReplaceInstUsesWith(I, Op0);
779 if (CI->isAllOnesValue()) // X * -1 == 0 - X
780 return BinaryOperator::createNeg(Op0, I.getName());
782 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
783 if (uint64_t C = Log2(Val)) // Replace X*(2^C) with X << C
784 return new ShiftInst(Instruction::Shl, Op0,
785 ConstantUInt::get(Type::UByteTy, C));
787 ConstantFP *Op1F = cast<ConstantFP>(Op1);
788 if (Op1F->isNullValue())
789 return ReplaceInstUsesWith(I, Op1);
791 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
792 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
793 if (Op1F->getValue() == 1.0)
794 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
797 // Try to fold constant mul into select arguments.
798 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
799 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
803 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
804 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
805 return BinaryOperator::create(Instruction::Mul, Op0v, Op1v);
807 // If one of the operands of the multiply is a cast from a boolean value, then
808 // we know the bool is either zero or one, so this is a 'masking' multiply.
809 // See if we can simplify things based on how the boolean was originally
811 CastInst *BoolCast = 0;
812 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
813 if (CI->getOperand(0)->getType() == Type::BoolTy)
816 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
817 if (CI->getOperand(0)->getType() == Type::BoolTy)
820 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
821 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
822 const Type *SCOpTy = SCIOp0->getType();
824 // If the setcc is true iff the sign bit of X is set, then convert this
825 // multiply into a shift/and combination.
826 if (isa<ConstantInt>(SCIOp1) &&
827 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
828 // Shift the X value right to turn it into "all signbits".
829 Constant *Amt = ConstantUInt::get(Type::UByteTy,
830 SCOpTy->getPrimitiveSize()*8-1);
831 if (SCIOp0->getType()->isUnsigned()) {
832 const Type *NewTy = getSignedIntegralType(SCIOp0->getType());
833 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
834 SCIOp0->getName()), I);
838 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
839 BoolCast->getOperand(0)->getName()+
842 // If the multiply type is not the same as the source type, sign extend
843 // or truncate to the multiply type.
844 if (I.getType() != V->getType())
845 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
847 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
848 return BinaryOperator::create(Instruction::And, V, OtherOp);
853 return Changed ? &I : 0;
856 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
858 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
859 if (RHS->equalsInt(1))
860 return ReplaceInstUsesWith(I, I.getOperand(0));
862 // Check to see if this is an unsigned division with an exact power of 2,
863 // if so, convert to a right shift.
864 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
865 if (uint64_t Val = C->getValue()) // Don't break X / 0
866 if (uint64_t C = Log2(Val))
867 return new ShiftInst(Instruction::Shr, I.getOperand(0),
868 ConstantUInt::get(Type::UByteTy, C));
871 // 0 / X == 0, we don't need to preserve faults!
872 if (ConstantInt *LHS = dyn_cast<ConstantInt>(I.getOperand(0)))
873 if (LHS->equalsInt(0))
874 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
880 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
881 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
882 if (RHS->equalsInt(1)) // X % 1 == 0
883 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
884 if (RHS->isAllOnesValue()) // X % -1 == 0
885 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
887 // Check to see if this is an unsigned remainder with an exact power of 2,
888 // if so, convert to a bitwise and.
889 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
890 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
892 return BinaryOperator::create(Instruction::And, I.getOperand(0),
893 ConstantUInt::get(I.getType(), Val-1));
896 // 0 % X == 0, we don't need to preserve faults!
897 if (ConstantInt *LHS = dyn_cast<ConstantInt>(I.getOperand(0)))
898 if (LHS->equalsInt(0))
899 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
904 // isMaxValueMinusOne - return true if this is Max-1
905 static bool isMaxValueMinusOne(const ConstantInt *C) {
906 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
907 // Calculate -1 casted to the right type...
908 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
909 uint64_t Val = ~0ULL; // All ones
910 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
911 return CU->getValue() == Val-1;
914 const ConstantSInt *CS = cast<ConstantSInt>(C);
916 // Calculate 0111111111..11111
917 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
918 int64_t Val = INT64_MAX; // All ones
919 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
920 return CS->getValue() == Val-1;
923 // isMinValuePlusOne - return true if this is Min+1
924 static bool isMinValuePlusOne(const ConstantInt *C) {
925 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
926 return CU->getValue() == 1;
928 const ConstantSInt *CS = cast<ConstantSInt>(C);
930 // Calculate 1111111111000000000000
931 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
932 int64_t Val = -1; // All ones
933 Val <<= TypeBits-1; // Shift over to the right spot
934 return CS->getValue() == Val+1;
937 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
938 /// are carefully arranged to allow folding of expressions such as:
940 /// (A < B) | (A > B) --> (A != B)
942 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
943 /// represents that the comparison is true if A == B, and bit value '1' is true
946 static unsigned getSetCondCode(const SetCondInst *SCI) {
947 switch (SCI->getOpcode()) {
949 case Instruction::SetGT: return 1;
950 case Instruction::SetEQ: return 2;
951 case Instruction::SetGE: return 3;
952 case Instruction::SetLT: return 4;
953 case Instruction::SetNE: return 5;
954 case Instruction::SetLE: return 6;
957 assert(0 && "Invalid SetCC opcode!");
962 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
963 /// opcode and two operands into either a constant true or false, or a brand new
964 /// SetCC instruction.
965 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
967 case 0: return ConstantBool::False;
968 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
969 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
970 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
971 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
972 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
973 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
974 case 7: return ConstantBool::True;
975 default: assert(0 && "Illegal SetCCCode!"); return 0;
979 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
980 struct FoldSetCCLogical {
983 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
984 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
985 bool shouldApply(Value *V) const {
986 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
987 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
988 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
991 Instruction *apply(BinaryOperator &Log) const {
992 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
993 if (SCI->getOperand(0) != LHS) {
994 assert(SCI->getOperand(1) == LHS);
995 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
998 unsigned LHSCode = getSetCondCode(SCI);
999 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
1001 switch (Log.getOpcode()) {
1002 case Instruction::And: Code = LHSCode & RHSCode; break;
1003 case Instruction::Or: Code = LHSCode | RHSCode; break;
1004 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
1005 default: assert(0 && "Illegal logical opcode!"); return 0;
1008 Value *RV = getSetCCValue(Code, LHS, RHS);
1009 if (Instruction *I = dyn_cast<Instruction>(RV))
1011 // Otherwise, it's a constant boolean value...
1012 return IC.ReplaceInstUsesWith(Log, RV);
1017 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
1018 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
1019 // guaranteed to be either a shift instruction or a binary operator.
1020 Instruction *InstCombiner::OptAndOp(Instruction *Op,
1021 ConstantIntegral *OpRHS,
1022 ConstantIntegral *AndRHS,
1023 BinaryOperator &TheAnd) {
1024 Value *X = Op->getOperand(0);
1025 Constant *Together = 0;
1026 if (!isa<ShiftInst>(Op))
1027 Together = ConstantExpr::get(Instruction::And, AndRHS, OpRHS);
1029 switch (Op->getOpcode()) {
1030 case Instruction::Xor:
1031 if (Together->isNullValue()) {
1032 // (X ^ C1) & C2 --> (X & C2) iff (C1&C2) == 0
1033 return BinaryOperator::create(Instruction::And, X, AndRHS);
1034 } else if (Op->hasOneUse()) {
1035 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
1036 std::string OpName = Op->getName(); Op->setName("");
1037 Instruction *And = BinaryOperator::create(Instruction::And,
1039 InsertNewInstBefore(And, TheAnd);
1040 return BinaryOperator::create(Instruction::Xor, And, Together);
1043 case Instruction::Or:
1044 // (X | C1) & C2 --> X & C2 iff C1 & C1 == 0
1045 if (Together->isNullValue())
1046 return BinaryOperator::create(Instruction::And, X, AndRHS);
1048 if (Together == AndRHS) // (X | C) & C --> C
1049 return ReplaceInstUsesWith(TheAnd, AndRHS);
1051 if (Op->hasOneUse() && Together != OpRHS) {
1052 // (X | C1) & C2 --> (X | (C1&C2)) & C2
1053 std::string Op0Name = Op->getName(); Op->setName("");
1054 Instruction *Or = BinaryOperator::create(Instruction::Or, X,
1056 InsertNewInstBefore(Or, TheAnd);
1057 return BinaryOperator::create(Instruction::And, Or, AndRHS);
1061 case Instruction::Add:
1062 if (Op->hasOneUse()) {
1063 // Adding a one to a single bit bit-field should be turned into an XOR
1064 // of the bit. First thing to check is to see if this AND is with a
1065 // single bit constant.
1066 unsigned long long AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
1068 // Clear bits that are not part of the constant.
1069 AndRHSV &= (1ULL << AndRHS->getType()->getPrimitiveSize()*8)-1;
1071 // If there is only one bit set...
1072 if ((AndRHSV & (AndRHSV-1)) == 0) {
1073 // Ok, at this point, we know that we are masking the result of the
1074 // ADD down to exactly one bit. If the constant we are adding has
1075 // no bits set below this bit, then we can eliminate the ADD.
1076 unsigned long long AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
1078 // Check to see if any bits below the one bit set in AndRHSV are set.
1079 if ((AddRHS & (AndRHSV-1)) == 0) {
1080 // If not, the only thing that can effect the output of the AND is
1081 // the bit specified by AndRHSV. If that bit is set, the effect of
1082 // the XOR is to toggle the bit. If it is clear, then the ADD has
1084 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
1085 TheAnd.setOperand(0, X);
1088 std::string Name = Op->getName(); Op->setName("");
1089 // Pull the XOR out of the AND.
1090 Instruction *NewAnd =
1091 BinaryOperator::create(Instruction::And, X, AndRHS, Name);
1092 InsertNewInstBefore(NewAnd, TheAnd);
1093 return BinaryOperator::create(Instruction::Xor, NewAnd, AndRHS);
1100 case Instruction::Shl: {
1101 // We know that the AND will not produce any of the bits shifted in, so if
1102 // the anded constant includes them, clear them now!
1104 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1105 Constant *CI = ConstantExpr::get(Instruction::And, AndRHS,
1106 ConstantExpr::get(Instruction::Shl, AllOne, OpRHS));
1108 TheAnd.setOperand(1, CI);
1113 case Instruction::Shr:
1114 // We know that the AND will not produce any of the bits shifted in, so if
1115 // the anded constant includes them, clear them now! This only applies to
1116 // unsigned shifts, because a signed shr may bring in set bits!
1118 if (AndRHS->getType()->isUnsigned()) {
1119 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1120 Constant *CI = ConstantExpr::get(Instruction::And, AndRHS,
1121 ConstantExpr::get(Instruction::Shr, AllOne, OpRHS));
1123 TheAnd.setOperand(1, CI);
1133 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1134 bool Changed = SimplifyCommutative(I);
1135 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1137 // and X, X = X and X, 0 == 0
1138 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
1139 return ReplaceInstUsesWith(I, Op1);
1142 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1143 if (RHS->isAllOnesValue())
1144 return ReplaceInstUsesWith(I, Op0);
1146 // Optimize a variety of ((val OP C1) & C2) combinations...
1147 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
1148 Instruction *Op0I = cast<Instruction>(Op0);
1149 Value *X = Op0I->getOperand(0);
1150 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1151 if (Instruction *Res = OptAndOp(Op0I, Op0CI, RHS, I))
1155 // Try to fold constant and into select arguments.
1156 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1157 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1161 Value *Op0NotVal = dyn_castNotVal(Op0);
1162 Value *Op1NotVal = dyn_castNotVal(Op1);
1164 // (~A & ~B) == (~(A | B)) - Demorgan's Law
1165 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1166 Instruction *Or = BinaryOperator::create(Instruction::Or, Op0NotVal,
1167 Op1NotVal,I.getName()+".demorgan");
1168 InsertNewInstBefore(Or, I);
1169 return BinaryOperator::createNot(Or);
1172 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1173 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1175 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1176 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
1177 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1180 return Changed ? &I : 0;
1185 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
1186 bool Changed = SimplifyCommutative(I);
1187 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1189 // or X, X = X or X, 0 == X
1190 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
1191 return ReplaceInstUsesWith(I, Op0);
1194 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1195 if (RHS->isAllOnesValue())
1196 return ReplaceInstUsesWith(I, Op1);
1198 if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
1199 // (X & C1) | C2 --> (X | C2) & (C1|C2)
1200 if (Op0I->getOpcode() == Instruction::And && isOnlyUse(Op0))
1201 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
1202 std::string Op0Name = Op0I->getName(); Op0I->setName("");
1203 Instruction *Or = BinaryOperator::create(Instruction::Or,
1204 Op0I->getOperand(0), RHS,
1206 InsertNewInstBefore(Or, I);
1207 return BinaryOperator::create(Instruction::And, Or,
1208 ConstantExpr::get(Instruction::Or, RHS, Op0CI));
1211 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
1212 if (Op0I->getOpcode() == Instruction::Xor && isOnlyUse(Op0))
1213 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
1214 std::string Op0Name = Op0I->getName(); Op0I->setName("");
1215 Instruction *Or = BinaryOperator::create(Instruction::Or,
1216 Op0I->getOperand(0), RHS,
1218 InsertNewInstBefore(Or, I);
1219 return BinaryOperator::create(Instruction::Xor, Or,
1220 ConstantExpr::get(Instruction::And, Op0CI,
1225 // Try to fold constant and into select arguments.
1226 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1227 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1231 // (A & C1)|(A & C2) == A & (C1|C2)
1232 if (Instruction *LHS = dyn_cast<BinaryOperator>(Op0))
1233 if (Instruction *RHS = dyn_cast<BinaryOperator>(Op1))
1234 if (LHS->getOperand(0) == RHS->getOperand(0))
1235 if (Constant *C0 = dyn_castMaskingAnd(LHS))
1236 if (Constant *C1 = dyn_castMaskingAnd(RHS))
1237 return BinaryOperator::create(Instruction::And, LHS->getOperand(0),
1238 ConstantExpr::get(Instruction::Or, C0, C1));
1240 Value *Op0NotVal = dyn_castNotVal(Op0);
1241 Value *Op1NotVal = dyn_castNotVal(Op1);
1243 if (Op1 == Op0NotVal) // ~A | A == -1
1244 return ReplaceInstUsesWith(I,
1245 ConstantIntegral::getAllOnesValue(I.getType()));
1247 if (Op0 == Op1NotVal) // A | ~A == -1
1248 return ReplaceInstUsesWith(I,
1249 ConstantIntegral::getAllOnesValue(I.getType()));
1251 // (~A | ~B) == (~(A & B)) - Demorgan's Law
1252 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1253 Instruction *And = BinaryOperator::create(Instruction::And, Op0NotVal,
1254 Op1NotVal,I.getName()+".demorgan",
1256 WorkList.push_back(And);
1257 return BinaryOperator::createNot(And);
1260 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
1261 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
1262 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1265 return Changed ? &I : 0;
1268 // XorSelf - Implements: X ^ X --> 0
1271 XorSelf(Value *rhs) : RHS(rhs) {}
1272 bool shouldApply(Value *LHS) const { return LHS == RHS; }
1273 Instruction *apply(BinaryOperator &Xor) const {
1279 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
1280 bool Changed = SimplifyCommutative(I);
1281 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1283 // xor X, X = 0, even if X is nested in a sequence of Xor's.
1284 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
1285 assert(Result == &I && "AssociativeOpt didn't work?");
1286 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1289 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1291 if (RHS->isNullValue())
1292 return ReplaceInstUsesWith(I, Op0);
1294 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
1295 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
1296 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
1297 if (RHS == ConstantBool::True && SCI->hasOneUse())
1298 return new SetCondInst(SCI->getInverseCondition(),
1299 SCI->getOperand(0), SCI->getOperand(1));
1301 // ~(c-X) == X-c-1 == X+(-c-1)
1302 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
1303 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
1304 Constant *NegOp0I0C = ConstantExpr::get(Instruction::Sub,
1305 Constant::getNullValue(Op0I0C->getType()), Op0I0C);
1306 Constant *ConstantRHS = ConstantExpr::get(Instruction::Sub, NegOp0I0C,
1307 ConstantInt::get(I.getType(), 1));
1308 return BinaryOperator::create(Instruction::Add, Op0I->getOperand(1),
1312 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1313 switch (Op0I->getOpcode()) {
1314 case Instruction::Add:
1315 // ~(X-c) --> (-c-1)-X
1316 if (RHS->isAllOnesValue()) {
1317 Constant *NegOp0CI = ConstantExpr::get(Instruction::Sub,
1318 Constant::getNullValue(Op0CI->getType()), Op0CI);
1319 return BinaryOperator::create(Instruction::Sub,
1320 ConstantExpr::get(Instruction::Sub, NegOp0CI,
1321 ConstantInt::get(I.getType(), 1)),
1322 Op0I->getOperand(0));
1325 case Instruction::And:
1326 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
1327 if (ConstantExpr::get(Instruction::And, RHS, Op0CI)->isNullValue())
1328 return BinaryOperator::create(Instruction::Or, Op0, RHS);
1330 case Instruction::Or:
1331 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
1332 if (ConstantExpr::get(Instruction::And, RHS, Op0CI) == RHS)
1333 return BinaryOperator::create(Instruction::And, Op0,
1340 // Try to fold constant and into select arguments.
1341 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1342 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1346 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
1348 return ReplaceInstUsesWith(I,
1349 ConstantIntegral::getAllOnesValue(I.getType()));
1351 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
1353 return ReplaceInstUsesWith(I,
1354 ConstantIntegral::getAllOnesValue(I.getType()));
1356 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
1357 if (Op1I->getOpcode() == Instruction::Or) {
1358 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
1359 cast<BinaryOperator>(Op1I)->swapOperands();
1361 std::swap(Op0, Op1);
1362 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
1364 std::swap(Op0, Op1);
1366 } else if (Op1I->getOpcode() == Instruction::Xor) {
1367 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
1368 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
1369 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
1370 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
1373 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
1374 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
1375 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
1376 cast<BinaryOperator>(Op0I)->swapOperands();
1377 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
1378 Value *NotB = BinaryOperator::createNot(Op1, Op1->getName()+".not", &I);
1379 WorkList.push_back(cast<Instruction>(NotB));
1380 return BinaryOperator::create(Instruction::And, Op0I->getOperand(0),
1383 } else if (Op0I->getOpcode() == Instruction::Xor) {
1384 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
1385 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
1386 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
1387 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
1390 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1^C2 == 0
1391 if (Constant *C1 = dyn_castMaskingAnd(Op0))
1392 if (Constant *C2 = dyn_castMaskingAnd(Op1))
1393 if (ConstantExpr::get(Instruction::And, C1, C2)->isNullValue())
1394 return BinaryOperator::create(Instruction::Or, Op0, Op1);
1396 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
1397 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
1398 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1401 return Changed ? &I : 0;
1404 // AddOne, SubOne - Add or subtract a constant one from an integer constant...
1405 static Constant *AddOne(ConstantInt *C) {
1406 Constant *Result = ConstantExpr::get(Instruction::Add, C,
1407 ConstantInt::get(C->getType(), 1));
1408 assert(Result && "Constant folding integer addition failed!");
1411 static Constant *SubOne(ConstantInt *C) {
1412 Constant *Result = ConstantExpr::get(Instruction::Sub, C,
1413 ConstantInt::get(C->getType(), 1));
1414 assert(Result && "Constant folding integer addition failed!");
1418 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
1419 // true when both operands are equal...
1421 static bool isTrueWhenEqual(Instruction &I) {
1422 return I.getOpcode() == Instruction::SetEQ ||
1423 I.getOpcode() == Instruction::SetGE ||
1424 I.getOpcode() == Instruction::SetLE;
1427 Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
1428 bool Changed = SimplifyCommutative(I);
1429 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1430 const Type *Ty = Op0->getType();
1434 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
1436 // setcc <global/alloca*>, 0 - Global/Stack value addresses are never null!
1437 if (isa<ConstantPointerNull>(Op1) &&
1438 (isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0)))
1439 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
1442 // setcc's with boolean values can always be turned into bitwise operations
1443 if (Ty == Type::BoolTy) {
1444 // If this is <, >, or !=, we can change this into a simple xor instruction
1445 if (!isTrueWhenEqual(I))
1446 return BinaryOperator::create(Instruction::Xor, Op0, Op1);
1448 // Otherwise we need to make a temporary intermediate instruction and insert
1449 // it into the instruction stream. This is what we are after:
1451 // seteq bool %A, %B -> ~(A^B)
1452 // setle bool %A, %B -> ~A | B
1453 // setge bool %A, %B -> A | ~B
1455 if (I.getOpcode() == Instruction::SetEQ) { // seteq case
1456 Instruction *Xor = BinaryOperator::create(Instruction::Xor, Op0, Op1,
1458 InsertNewInstBefore(Xor, I);
1459 return BinaryOperator::createNot(Xor);
1462 // Handle the setXe cases...
1463 assert(I.getOpcode() == Instruction::SetGE ||
1464 I.getOpcode() == Instruction::SetLE);
1466 if (I.getOpcode() == Instruction::SetGE)
1467 std::swap(Op0, Op1); // Change setge -> setle
1469 // Now we just have the SetLE case.
1470 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
1471 InsertNewInstBefore(Not, I);
1472 return BinaryOperator::create(Instruction::Or, Not, Op1);
1475 // Check to see if we are doing one of many comparisons against constant
1476 // integers at the end of their ranges...
1478 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
1479 // Simplify seteq and setne instructions...
1480 if (I.getOpcode() == Instruction::SetEQ ||
1481 I.getOpcode() == Instruction::SetNE) {
1482 bool isSetNE = I.getOpcode() == Instruction::SetNE;
1484 // If the first operand is (and|or|xor) with a constant, and the second
1485 // operand is a constant, simplify a bit.
1486 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
1487 switch (BO->getOpcode()) {
1488 case Instruction::Add:
1489 if (CI->isNullValue()) {
1490 // Replace ((add A, B) != 0) with (A != -B) if A or B is
1491 // efficiently invertible, or if the add has just this one use.
1492 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
1493 if (Value *NegVal = dyn_castNegVal(BOp1))
1494 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
1495 else if (Value *NegVal = dyn_castNegVal(BOp0))
1496 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
1497 else if (BO->hasOneUse()) {
1498 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
1500 InsertNewInstBefore(Neg, I);
1501 return new SetCondInst(I.getOpcode(), BOp0, Neg);
1505 case Instruction::Xor:
1506 // For the xor case, we can xor two constants together, eliminating
1507 // the explicit xor.
1508 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
1509 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
1510 ConstantExpr::get(Instruction::Xor, CI, BOC));
1513 case Instruction::Sub:
1514 // Replace (([sub|xor] A, B) != 0) with (A != B)
1515 if (CI->isNullValue())
1516 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
1520 case Instruction::Or:
1521 // If bits are being or'd in that are not present in the constant we
1522 // are comparing against, then the comparison could never succeed!
1523 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
1524 Constant *NotCI = NotConstant(CI);
1525 if (!ConstantExpr::get(Instruction::And, BOC, NotCI)->isNullValue())
1526 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
1530 case Instruction::And:
1531 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
1532 // If bits are being compared against that are and'd out, then the
1533 // comparison can never succeed!
1534 if (!ConstantExpr::get(Instruction::And, CI,
1535 NotConstant(BOC))->isNullValue())
1536 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
1538 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
1539 // to be a signed value as appropriate.
1540 if (isSignBit(BOC)) {
1541 Value *X = BO->getOperand(0);
1542 // If 'X' is not signed, insert a cast now...
1543 if (!BOC->getType()->isSigned()) {
1544 const Type *DestTy = getSignedIntegralType(BOC->getType());
1545 CastInst *NewCI = new CastInst(X,DestTy,X->getName()+".signed");
1546 InsertNewInstBefore(NewCI, I);
1549 return new SetCondInst(isSetNE ? Instruction::SetLT :
1550 Instruction::SetGE, X,
1551 Constant::getNullValue(X->getType()));
1557 } else { // Not a SetEQ/SetNE
1558 // If the LHS is a cast from an integral value of the same size,
1559 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
1560 Value *CastOp = Cast->getOperand(0);
1561 const Type *SrcTy = CastOp->getType();
1562 unsigned SrcTySize = SrcTy->getPrimitiveSize();
1563 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
1564 SrcTySize == Cast->getType()->getPrimitiveSize()) {
1565 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
1566 "Source and destination signednesses should differ!");
1567 if (Cast->getType()->isSigned()) {
1568 // If this is a signed comparison, check for comparisons in the
1569 // vicinity of zero.
1570 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
1572 return BinaryOperator::create(Instruction::SetGT, CastOp,
1573 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize*8-1))-1));
1574 else if (I.getOpcode() == Instruction::SetGT &&
1575 cast<ConstantSInt>(CI)->getValue() == -1)
1576 // X > -1 => x < 128
1577 return BinaryOperator::create(Instruction::SetLT, CastOp,
1578 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize*8-1)));
1580 ConstantUInt *CUI = cast<ConstantUInt>(CI);
1581 if (I.getOpcode() == Instruction::SetLT &&
1582 CUI->getValue() == 1ULL << (SrcTySize*8-1))
1583 // X < 128 => X > -1
1584 return BinaryOperator::create(Instruction::SetGT, CastOp,
1585 ConstantSInt::get(SrcTy, -1));
1586 else if (I.getOpcode() == Instruction::SetGT &&
1587 CUI->getValue() == (1ULL << (SrcTySize*8-1))-1)
1589 return BinaryOperator::create(Instruction::SetLT, CastOp,
1590 Constant::getNullValue(SrcTy));
1596 // Check to see if we are comparing against the minimum or maximum value...
1597 if (CI->isMinValue()) {
1598 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
1599 return ReplaceInstUsesWith(I, ConstantBool::False);
1600 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
1601 return ReplaceInstUsesWith(I, ConstantBool::True);
1602 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
1603 return BinaryOperator::create(Instruction::SetEQ, Op0, Op1);
1604 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
1605 return BinaryOperator::create(Instruction::SetNE, Op0, Op1);
1607 } else if (CI->isMaxValue()) {
1608 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
1609 return ReplaceInstUsesWith(I, ConstantBool::False);
1610 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
1611 return ReplaceInstUsesWith(I, ConstantBool::True);
1612 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
1613 return BinaryOperator::create(Instruction::SetEQ, Op0, Op1);
1614 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
1615 return BinaryOperator::create(Instruction::SetNE, Op0, Op1);
1617 // Comparing against a value really close to min or max?
1618 } else if (isMinValuePlusOne(CI)) {
1619 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
1620 return BinaryOperator::create(Instruction::SetEQ, Op0, SubOne(CI));
1621 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
1622 return BinaryOperator::create(Instruction::SetNE, Op0, SubOne(CI));
1624 } else if (isMaxValueMinusOne(CI)) {
1625 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
1626 return BinaryOperator::create(Instruction::SetEQ, Op0, AddOne(CI));
1627 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
1628 return BinaryOperator::create(Instruction::SetNE, Op0, AddOne(CI));
1631 // If we still have a setle or setge instruction, turn it into the
1632 // appropriate setlt or setgt instruction. Since the border cases have
1633 // already been handled above, this requires little checking.
1635 if (I.getOpcode() == Instruction::SetLE)
1636 return BinaryOperator::create(Instruction::SetLT, Op0, AddOne(CI));
1637 if (I.getOpcode() == Instruction::SetGE)
1638 return BinaryOperator::create(Instruction::SetGT, Op0, SubOne(CI));
1641 // Test to see if the operands of the setcc are casted versions of other
1642 // values. If the cast can be stripped off both arguments, we do so now.
1643 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
1644 Value *CastOp0 = CI->getOperand(0);
1645 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
1646 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
1647 (I.getOpcode() == Instruction::SetEQ ||
1648 I.getOpcode() == Instruction::SetNE)) {
1649 // We keep moving the cast from the left operand over to the right
1650 // operand, where it can often be eliminated completely.
1653 // If operand #1 is a cast instruction, see if we can eliminate it as
1655 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
1656 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
1658 Op1 = CI2->getOperand(0);
1660 // If Op1 is a constant, we can fold the cast into the constant.
1661 if (Op1->getType() != Op0->getType())
1662 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
1663 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
1665 // Otherwise, cast the RHS right before the setcc
1666 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
1667 InsertNewInstBefore(cast<Instruction>(Op1), I);
1669 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
1672 // Handle the special case of: setcc (cast bool to X), <cst>
1673 // This comes up when you have code like
1676 // For generality, we handle any zero-extension of any operand comparison
1678 if (ConstantInt *ConstantRHS = dyn_cast<ConstantInt>(Op1)) {
1679 const Type *SrcTy = CastOp0->getType();
1680 const Type *DestTy = Op0->getType();
1681 if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
1682 (SrcTy->isUnsigned() || SrcTy == Type::BoolTy)) {
1683 // Ok, we have an expansion of operand 0 into a new type. Get the
1684 // constant value, masink off bits which are not set in the RHS. These
1685 // could be set if the destination value is signed.
1686 uint64_t ConstVal = ConstantRHS->getRawValue();
1687 ConstVal &= (1ULL << DestTy->getPrimitiveSize()*8)-1;
1689 // If the constant we are comparing it with has high bits set, which
1690 // don't exist in the original value, the values could never be equal,
1691 // because the source would be zero extended.
1693 SrcTy == Type::BoolTy ? 1 : SrcTy->getPrimitiveSize()*8;
1694 bool HasSignBit = ConstVal & (1ULL << (DestTy->getPrimitiveSize()*8-1));
1695 if (ConstVal & ~((1ULL << SrcBits)-1)) {
1696 switch (I.getOpcode()) {
1697 default: assert(0 && "Unknown comparison type!");
1698 case Instruction::SetEQ:
1699 return ReplaceInstUsesWith(I, ConstantBool::False);
1700 case Instruction::SetNE:
1701 return ReplaceInstUsesWith(I, ConstantBool::True);
1702 case Instruction::SetLT:
1703 case Instruction::SetLE:
1704 if (DestTy->isSigned() && HasSignBit)
1705 return ReplaceInstUsesWith(I, ConstantBool::False);
1706 return ReplaceInstUsesWith(I, ConstantBool::True);
1707 case Instruction::SetGT:
1708 case Instruction::SetGE:
1709 if (DestTy->isSigned() && HasSignBit)
1710 return ReplaceInstUsesWith(I, ConstantBool::True);
1711 return ReplaceInstUsesWith(I, ConstantBool::False);
1715 // Otherwise, we can replace the setcc with a setcc of the smaller
1717 Op1 = ConstantExpr::getCast(cast<Constant>(Op1), SrcTy);
1718 return BinaryOperator::create(I.getOpcode(), CastOp0, Op1);
1722 return Changed ? &I : 0;
1727 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
1728 assert(I.getOperand(1)->getType() == Type::UByteTy);
1729 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1730 bool isLeftShift = I.getOpcode() == Instruction::Shl;
1732 // shl X, 0 == X and shr X, 0 == X
1733 // shl 0, X == 0 and shr 0, X == 0
1734 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
1735 Op0 == Constant::getNullValue(Op0->getType()))
1736 return ReplaceInstUsesWith(I, Op0);
1738 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
1740 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
1741 if (CSI->isAllOnesValue())
1742 return ReplaceInstUsesWith(I, CSI);
1744 // Try to fold constant and into select arguments.
1745 if (isa<Constant>(Op0))
1746 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1747 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1750 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
1751 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
1752 // of a signed value.
1754 unsigned TypeBits = Op0->getType()->getPrimitiveSize()*8;
1755 if (CUI->getValue() >= TypeBits) {
1756 if (!Op0->getType()->isSigned() || isLeftShift)
1757 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
1759 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
1764 // ((X*C1) << C2) == (X * (C1 << C2))
1765 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
1766 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
1767 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
1768 return BinaryOperator::create(Instruction::Mul, BO->getOperand(0),
1769 ConstantExpr::get(Instruction::Shl, BOOp, CUI));
1771 // Try to fold constant and into select arguments.
1772 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1773 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1776 // If the operand is an bitwise operator with a constant RHS, and the
1777 // shift is the only use, we can pull it out of the shift.
1778 if (Op0->hasOneUse())
1779 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0))
1780 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
1781 bool isValid = true; // Valid only for And, Or, Xor
1782 bool highBitSet = false; // Transform if high bit of constant set?
1784 switch (Op0BO->getOpcode()) {
1785 default: isValid = false; break; // Do not perform transform!
1786 case Instruction::Or:
1787 case Instruction::Xor:
1790 case Instruction::And:
1795 // If this is a signed shift right, and the high bit is modified
1796 // by the logical operation, do not perform the transformation.
1797 // The highBitSet boolean indicates the value of the high bit of
1798 // the constant which would cause it to be modified for this
1801 if (isValid && !isLeftShift && !I.getType()->isUnsigned()) {
1802 uint64_t Val = Op0C->getRawValue();
1803 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
1807 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI);
1809 Instruction *NewShift =
1810 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI,
1813 InsertNewInstBefore(NewShift, I);
1815 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
1820 // If this is a shift of a shift, see if we can fold the two together...
1821 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
1822 if (ConstantUInt *ShiftAmt1C =
1823 dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) {
1824 unsigned ShiftAmt1 = ShiftAmt1C->getValue();
1825 unsigned ShiftAmt2 = CUI->getValue();
1827 // Check for (A << c1) << c2 and (A >> c1) >> c2
1828 if (I.getOpcode() == Op0SI->getOpcode()) {
1829 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
1830 if (Op0->getType()->getPrimitiveSize()*8 < Amt)
1831 Amt = Op0->getType()->getPrimitiveSize()*8;
1832 return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
1833 ConstantUInt::get(Type::UByteTy, Amt));
1836 // Check for (A << c1) >> c2 or visaversa. If we are dealing with
1837 // signed types, we can only support the (A >> c1) << c2 configuration,
1838 // because it can not turn an arbitrary bit of A into a sign bit.
1839 if (I.getType()->isUnsigned() || isLeftShift) {
1840 // Calculate bitmask for what gets shifted off the edge...
1841 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
1843 C = ConstantExpr::get(Instruction::Shl, C, ShiftAmt1C);
1845 C = ConstantExpr::get(Instruction::Shr, C, ShiftAmt1C);
1848 BinaryOperator::create(Instruction::And, Op0SI->getOperand(0),
1849 C, Op0SI->getOperand(0)->getName()+".mask");
1850 InsertNewInstBefore(Mask, I);
1852 // Figure out what flavor of shift we should use...
1853 if (ShiftAmt1 == ShiftAmt2)
1854 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
1855 else if (ShiftAmt1 < ShiftAmt2) {
1856 return new ShiftInst(I.getOpcode(), Mask,
1857 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
1859 return new ShiftInst(Op0SI->getOpcode(), Mask,
1860 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
1870 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
1873 static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
1874 const Type *DstTy) {
1876 // It is legal to eliminate the instruction if casting A->B->A if the sizes
1877 // are identical and the bits don't get reinterpreted (for example
1878 // int->float->int would not be allowed)
1879 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
1882 // Allow free casting and conversion of sizes as long as the sign doesn't
1884 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
1885 unsigned SrcSize = SrcTy->getPrimitiveSize();
1886 unsigned MidSize = MidTy->getPrimitiveSize();
1887 unsigned DstSize = DstTy->getPrimitiveSize();
1889 // Cases where we are monotonically decreasing the size of the type are
1890 // always ok, regardless of what sign changes are going on.
1892 if (SrcSize >= MidSize && MidSize >= DstSize)
1895 // Cases where the source and destination type are the same, but the middle
1896 // type is bigger are noops.
1898 if (SrcSize == DstSize && MidSize > SrcSize)
1901 // If we are monotonically growing, things are more complex.
1903 if (SrcSize <= MidSize && MidSize <= DstSize) {
1904 // We have eight combinations of signedness to worry about. Here's the
1906 static const int SignTable[8] = {
1907 // CODE, SrcSigned, MidSigned, DstSigned, Comment
1908 1, // U U U Always ok
1909 1, // U U S Always ok
1910 3, // U S U Ok iff SrcSize != MidSize
1911 3, // U S S Ok iff SrcSize != MidSize
1912 0, // S U U Never ok
1913 2, // S U S Ok iff MidSize == DstSize
1914 1, // S S U Always ok
1915 1, // S S S Always ok
1918 // Choose an action based on the current entry of the signtable that this
1919 // cast of cast refers to...
1920 unsigned Row = SrcTy->isSigned()*4+MidTy->isSigned()*2+DstTy->isSigned();
1921 switch (SignTable[Row]) {
1922 case 0: return false; // Never ok
1923 case 1: return true; // Always ok
1924 case 2: return MidSize == DstSize; // Ok iff MidSize == DstSize
1925 case 3: // Ok iff SrcSize != MidSize
1926 return SrcSize != MidSize || SrcTy == Type::BoolTy;
1927 default: assert(0 && "Bad entry in sign table!");
1932 // Otherwise, we cannot succeed. Specifically we do not want to allow things
1933 // like: short -> ushort -> uint, because this can create wrong results if
1934 // the input short is negative!
1939 static bool ValueRequiresCast(const Value *V, const Type *Ty) {
1940 if (V->getType() == Ty || isa<Constant>(V)) return false;
1941 if (const CastInst *CI = dyn_cast<CastInst>(V))
1942 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty))
1947 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
1948 /// InsertBefore instruction. This is specialized a bit to avoid inserting
1949 /// casts that are known to not do anything...
1951 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
1952 Instruction *InsertBefore) {
1953 if (V->getType() == DestTy) return V;
1954 if (Constant *C = dyn_cast<Constant>(V))
1955 return ConstantExpr::getCast(C, DestTy);
1957 CastInst *CI = new CastInst(V, DestTy, V->getName());
1958 InsertNewInstBefore(CI, *InsertBefore);
1962 // CastInst simplification
1964 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
1965 Value *Src = CI.getOperand(0);
1967 // If the user is casting a value to the same type, eliminate this cast
1969 if (CI.getType() == Src->getType())
1970 return ReplaceInstUsesWith(CI, Src);
1972 // If casting the result of another cast instruction, try to eliminate this
1975 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) {
1976 if (isEliminableCastOfCast(CSrc->getOperand(0)->getType(),
1977 CSrc->getType(), CI.getType())) {
1978 // This instruction now refers directly to the cast's src operand. This
1979 // has a good chance of making CSrc dead.
1980 CI.setOperand(0, CSrc->getOperand(0));
1984 // If this is an A->B->A cast, and we are dealing with integral types, try
1985 // to convert this into a logical 'and' instruction.
1987 if (CSrc->getOperand(0)->getType() == CI.getType() &&
1988 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
1989 CI.getType()->isUnsigned() && CSrc->getType()->isUnsigned() &&
1990 CSrc->getType()->getPrimitiveSize() < CI.getType()->getPrimitiveSize()){
1991 assert(CSrc->getType() != Type::ULongTy &&
1992 "Cannot have type bigger than ulong!");
1993 uint64_t AndValue = (1ULL << CSrc->getType()->getPrimitiveSize()*8)-1;
1994 Constant *AndOp = ConstantUInt::get(CI.getType(), AndValue);
1995 return BinaryOperator::create(Instruction::And, CSrc->getOperand(0),
2000 // If casting the result of a getelementptr instruction with no offset, turn
2001 // this into a cast of the original pointer!
2003 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
2004 bool AllZeroOperands = true;
2005 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
2006 if (!isa<Constant>(GEP->getOperand(i)) ||
2007 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
2008 AllZeroOperands = false;
2011 if (AllZeroOperands) {
2012 CI.setOperand(0, GEP->getOperand(0));
2017 // If we are casting a malloc or alloca to a pointer to a type of the same
2018 // size, rewrite the allocation instruction to allocate the "right" type.
2020 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
2021 if (AI->hasOneUse() && !AI->isArrayAllocation())
2022 if (const PointerType *PTy = dyn_cast<PointerType>(CI.getType())) {
2023 // Get the type really allocated and the type casted to...
2024 const Type *AllocElTy = AI->getAllocatedType();
2025 unsigned AllocElTySize = TD->getTypeSize(AllocElTy);
2026 const Type *CastElTy = PTy->getElementType();
2027 unsigned CastElTySize = TD->getTypeSize(CastElTy);
2029 // If the allocation is for an even multiple of the cast type size
2030 if (CastElTySize && (AllocElTySize % CastElTySize == 0)) {
2031 Value *Amt = ConstantUInt::get(Type::UIntTy,
2032 AllocElTySize/CastElTySize);
2033 std::string Name = AI->getName(); AI->setName("");
2034 AllocationInst *New;
2035 if (isa<MallocInst>(AI))
2036 New = new MallocInst(CastElTy, Amt, Name);
2038 New = new AllocaInst(CastElTy, Amt, Name);
2039 InsertNewInstBefore(New, CI);
2040 return ReplaceInstUsesWith(CI, New);
2044 // If the source value is an instruction with only this use, we can attempt to
2045 // propagate the cast into the instruction. Also, only handle integral types
2047 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
2048 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
2049 CI.getType()->isInteger()) { // Don't mess with casts to bool here
2050 const Type *DestTy = CI.getType();
2051 unsigned SrcBitSize = getTypeSizeInBits(Src->getType());
2052 unsigned DestBitSize = getTypeSizeInBits(DestTy);
2054 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
2055 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
2057 switch (SrcI->getOpcode()) {
2058 case Instruction::Add:
2059 case Instruction::Mul:
2060 case Instruction::And:
2061 case Instruction::Or:
2062 case Instruction::Xor:
2063 // If we are discarding information, or just changing the sign, rewrite.
2064 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
2065 // Don't insert two casts if they cannot be eliminated. We allow two
2066 // casts to be inserted if the sizes are the same. This could only be
2067 // converting signedness, which is a noop.
2068 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy) ||
2069 !ValueRequiresCast(Op0, DestTy)) {
2070 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
2071 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
2072 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
2073 ->getOpcode(), Op0c, Op1c);
2077 case Instruction::Shl:
2078 // Allow changing the sign of the source operand. Do not allow changing
2079 // the size of the shift, UNLESS the shift amount is a constant. We
2080 // mush not change variable sized shifts to a smaller size, because it
2081 // is undefined to shift more bits out than exist in the value.
2082 if (DestBitSize == SrcBitSize ||
2083 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
2084 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
2085 return new ShiftInst(Instruction::Shl, Op0c, Op1);
2094 /// GetSelectFoldableOperands - We want to turn code that looks like this:
2096 /// %D = select %cond, %C, %A
2098 /// %C = select %cond, %B, 0
2101 /// Assuming that the specified instruction is an operand to the select, return
2102 /// a bitmask indicating which operands of this instruction are foldable if they
2103 /// equal the other incoming value of the select.
2105 static unsigned GetSelectFoldableOperands(Instruction *I) {
2106 switch (I->getOpcode()) {
2107 case Instruction::Add:
2108 case Instruction::Mul:
2109 case Instruction::And:
2110 case Instruction::Or:
2111 case Instruction::Xor:
2112 return 3; // Can fold through either operand.
2113 case Instruction::Sub: // Can only fold on the amount subtracted.
2114 case Instruction::Shl: // Can only fold on the shift amount.
2115 case Instruction::Shr:
2118 return 0; // Cannot fold
2122 /// GetSelectFoldableConstant - For the same transformation as the previous
2123 /// function, return the identity constant that goes into the select.
2124 static Constant *GetSelectFoldableConstant(Instruction *I) {
2125 switch (I->getOpcode()) {
2126 default: assert(0 && "This cannot happen!"); abort();
2127 case Instruction::Add:
2128 case Instruction::Sub:
2129 case Instruction::Or:
2130 case Instruction::Xor:
2131 return Constant::getNullValue(I->getType());
2132 case Instruction::Shl:
2133 case Instruction::Shr:
2134 return Constant::getNullValue(Type::UByteTy);
2135 case Instruction::And:
2136 return ConstantInt::getAllOnesValue(I->getType());
2137 case Instruction::Mul:
2138 return ConstantInt::get(I->getType(), 1);
2142 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
2143 Value *CondVal = SI.getCondition();
2144 Value *TrueVal = SI.getTrueValue();
2145 Value *FalseVal = SI.getFalseValue();
2147 // select true, X, Y -> X
2148 // select false, X, Y -> Y
2149 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
2150 if (C == ConstantBool::True)
2151 return ReplaceInstUsesWith(SI, TrueVal);
2153 assert(C == ConstantBool::False);
2154 return ReplaceInstUsesWith(SI, FalseVal);
2157 // select C, X, X -> X
2158 if (TrueVal == FalseVal)
2159 return ReplaceInstUsesWith(SI, TrueVal);
2161 if (SI.getType() == Type::BoolTy)
2162 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
2163 if (C == ConstantBool::True) {
2164 // Change: A = select B, true, C --> A = or B, C
2165 return BinaryOperator::create(Instruction::Or, CondVal, FalseVal);
2167 // Change: A = select B, false, C --> A = and !B, C
2169 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
2170 "not."+CondVal->getName()), SI);
2171 return BinaryOperator::create(Instruction::And, NotCond, FalseVal);
2173 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
2174 if (C == ConstantBool::False) {
2175 // Change: A = select B, C, false --> A = and B, C
2176 return BinaryOperator::create(Instruction::And, CondVal, TrueVal);
2178 // Change: A = select B, C, true --> A = or !B, C
2180 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
2181 "not."+CondVal->getName()), SI);
2182 return BinaryOperator::create(Instruction::Or, NotCond, TrueVal);
2186 // Selecting between two integer constants?
2187 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
2188 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
2189 // select C, 1, 0 -> cast C to int
2190 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
2191 return new CastInst(CondVal, SI.getType());
2192 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
2193 // select C, 0, 1 -> cast !C to int
2195 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
2196 "not."+CondVal->getName()), SI);
2197 return new CastInst(NotCond, SI.getType());
2201 // See if we can fold the select into one of our operands.
2202 if (SI.getType()->isInteger()) {
2203 // See the comment above GetSelectFoldableOperands for a description of the
2204 // transformation we are doing here.
2205 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
2206 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
2207 !isa<Constant>(FalseVal))
2208 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
2209 unsigned OpToFold = 0;
2210 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
2212 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
2217 Constant *C = GetSelectFoldableConstant(TVI);
2218 std::string Name = TVI->getName(); TVI->setName("");
2219 Instruction *NewSel =
2220 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
2222 InsertNewInstBefore(NewSel, SI);
2223 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
2224 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
2225 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
2226 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
2228 assert(0 && "Unknown instruction!!");
2233 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
2234 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
2235 !isa<Constant>(TrueVal))
2236 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
2237 unsigned OpToFold = 0;
2238 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
2240 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
2245 Constant *C = GetSelectFoldableConstant(FVI);
2246 std::string Name = FVI->getName(); FVI->setName("");
2247 Instruction *NewSel =
2248 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
2250 InsertNewInstBefore(NewSel, SI);
2251 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
2252 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
2253 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
2254 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
2256 assert(0 && "Unknown instruction!!");
2265 // CallInst simplification
2267 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
2268 // Intrinsics cannot occur in an invoke, so handle them here instead of in
2270 if (Function *F = CI.getCalledFunction())
2271 switch (F->getIntrinsicID()) {
2272 case Intrinsic::memmove:
2273 case Intrinsic::memcpy:
2274 case Intrinsic::memset:
2275 // memmove/cpy/set of zero bytes is a noop.
2276 if (Constant *NumBytes = dyn_cast<Constant>(CI.getOperand(3))) {
2277 if (NumBytes->isNullValue())
2278 return EraseInstFromFunction(CI);
2285 return visitCallSite(&CI);
2288 // InvokeInst simplification
2290 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
2291 return visitCallSite(&II);
2294 // visitCallSite - Improvements for call and invoke instructions.
2296 Instruction *InstCombiner::visitCallSite(CallSite CS) {
2297 bool Changed = false;
2299 // If the callee is a constexpr cast of a function, attempt to move the cast
2300 // to the arguments of the call/invoke.
2301 if (transformConstExprCastCall(CS)) return 0;
2303 Value *Callee = CS.getCalledValue();
2304 const PointerType *PTy = cast<PointerType>(Callee->getType());
2305 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
2306 if (FTy->isVarArg()) {
2307 // See if we can optimize any arguments passed through the varargs area of
2309 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
2310 E = CS.arg_end(); I != E; ++I)
2311 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
2312 // If this cast does not effect the value passed through the varargs
2313 // area, we can eliminate the use of the cast.
2314 Value *Op = CI->getOperand(0);
2315 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
2322 return Changed ? CS.getInstruction() : 0;
2325 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
2326 // attempt to move the cast to the arguments of the call/invoke.
2328 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
2329 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
2330 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
2331 if (CE->getOpcode() != Instruction::Cast ||
2332 !isa<ConstantPointerRef>(CE->getOperand(0)))
2334 ConstantPointerRef *CPR = cast<ConstantPointerRef>(CE->getOperand(0));
2335 if (!isa<Function>(CPR->getValue())) return false;
2336 Function *Callee = cast<Function>(CPR->getValue());
2337 Instruction *Caller = CS.getInstruction();
2339 // Okay, this is a cast from a function to a different type. Unless doing so
2340 // would cause a type conversion of one of our arguments, change this call to
2341 // be a direct call with arguments casted to the appropriate types.
2343 const FunctionType *FT = Callee->getFunctionType();
2344 const Type *OldRetTy = Caller->getType();
2346 // Check to see if we are changing the return type...
2347 if (OldRetTy != FT->getReturnType()) {
2348 if (Callee->isExternal() &&
2349 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
2350 !Caller->use_empty())
2351 return false; // Cannot transform this return value...
2353 // If the callsite is an invoke instruction, and the return value is used by
2354 // a PHI node in a successor, we cannot change the return type of the call
2355 // because there is no place to put the cast instruction (without breaking
2356 // the critical edge). Bail out in this case.
2357 if (!Caller->use_empty())
2358 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
2359 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
2361 if (PHINode *PN = dyn_cast<PHINode>(*UI))
2362 if (PN->getParent() == II->getNormalDest() ||
2363 PN->getParent() == II->getUnwindDest())
2367 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
2368 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
2370 CallSite::arg_iterator AI = CS.arg_begin();
2371 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
2372 const Type *ParamTy = FT->getParamType(i);
2373 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
2374 if (Callee->isExternal() && !isConvertible) return false;
2377 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
2378 Callee->isExternal())
2379 return false; // Do not delete arguments unless we have a function body...
2381 // Okay, we decided that this is a safe thing to do: go ahead and start
2382 // inserting cast instructions as necessary...
2383 std::vector<Value*> Args;
2384 Args.reserve(NumActualArgs);
2386 AI = CS.arg_begin();
2387 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
2388 const Type *ParamTy = FT->getParamType(i);
2389 if ((*AI)->getType() == ParamTy) {
2390 Args.push_back(*AI);
2392 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
2397 // If the function takes more arguments than the call was taking, add them
2399 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
2400 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
2402 // If we are removing arguments to the function, emit an obnoxious warning...
2403 if (FT->getNumParams() < NumActualArgs)
2404 if (!FT->isVarArg()) {
2405 std::cerr << "WARNING: While resolving call to function '"
2406 << Callee->getName() << "' arguments were dropped!\n";
2408 // Add all of the arguments in their promoted form to the arg list...
2409 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
2410 const Type *PTy = getPromotedType((*AI)->getType());
2411 if (PTy != (*AI)->getType()) {
2412 // Must promote to pass through va_arg area!
2413 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
2414 InsertNewInstBefore(Cast, *Caller);
2415 Args.push_back(Cast);
2417 Args.push_back(*AI);
2422 if (FT->getReturnType() == Type::VoidTy)
2423 Caller->setName(""); // Void type should not have a name...
2426 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
2427 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
2428 Args, Caller->getName(), Caller);
2430 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
2433 // Insert a cast of the return type as necessary...
2435 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
2436 if (NV->getType() != Type::VoidTy) {
2437 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
2439 // If this is an invoke instruction, we should insert it after the first
2440 // non-phi, instruction in the normal successor block.
2441 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
2442 BasicBlock::iterator I = II->getNormalDest()->begin();
2443 while (isa<PHINode>(I)) ++I;
2444 InsertNewInstBefore(NC, *I);
2446 // Otherwise, it's a call, just insert cast right after the call instr
2447 InsertNewInstBefore(NC, *Caller);
2449 AddUsersToWorkList(*Caller);
2451 NV = Constant::getNullValue(Caller->getType());
2455 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
2456 Caller->replaceAllUsesWith(NV);
2457 Caller->getParent()->getInstList().erase(Caller);
2458 removeFromWorkList(Caller);
2464 // PHINode simplification
2466 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
2467 if (Value *V = hasConstantValue(&PN))
2468 return ReplaceInstUsesWith(PN, V);
2470 // If the only user of this instruction is a cast instruction, and all of the
2471 // incoming values are constants, change this PHI to merge together the casted
2474 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
2475 if (CI->getType() != PN.getType()) { // noop casts will be folded
2476 bool AllConstant = true;
2477 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
2478 if (!isa<Constant>(PN.getIncomingValue(i))) {
2479 AllConstant = false;
2483 // Make a new PHI with all casted values.
2484 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
2485 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2486 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
2487 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
2488 PN.getIncomingBlock(i));
2491 // Update the cast instruction.
2492 CI->setOperand(0, New);
2493 WorkList.push_back(CI); // revisit the cast instruction to fold.
2494 WorkList.push_back(New); // Make sure to revisit the new Phi
2495 return &PN; // PN is now dead!
2501 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
2502 Instruction *InsertPoint,
2504 unsigned PS = IC->getTargetData().getPointerSize();
2505 const Type *VTy = V->getType();
2507 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
2508 // We must insert a cast to ensure we sign-extend.
2509 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
2510 V->getName()), *InsertPoint);
2511 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
2516 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
2517 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
2518 // If so, eliminate the noop.
2519 if (GEP.getNumOperands() == 1)
2520 return ReplaceInstUsesWith(GEP, GEP.getOperand(0));
2522 bool HasZeroPointerIndex = false;
2523 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
2524 HasZeroPointerIndex = C->isNullValue();
2526 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
2527 return ReplaceInstUsesWith(GEP, GEP.getOperand(0));
2529 // Eliminate unneeded casts for indices.
2530 bool MadeChange = false;
2531 gep_type_iterator GTI = gep_type_begin(GEP);
2532 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
2533 if (isa<SequentialType>(*GTI)) {
2534 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
2535 Value *Src = CI->getOperand(0);
2536 const Type *SrcTy = Src->getType();
2537 const Type *DestTy = CI->getType();
2538 if (Src->getType()->isInteger()) {
2539 if (SrcTy->getPrimitiveSize() == DestTy->getPrimitiveSize()) {
2540 // We can always eliminate a cast from ulong or long to the other.
2541 // We can always eliminate a cast from uint to int or the other on
2542 // 32-bit pointer platforms.
2543 if (DestTy->getPrimitiveSize() >= TD->getPointerSize()) {
2545 GEP.setOperand(i, Src);
2547 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
2548 SrcTy->getPrimitiveSize() == 4) {
2549 // We can always eliminate a cast from int to [u]long. We can
2550 // eliminate a cast from uint to [u]long iff the target is a 32-bit
2552 if (SrcTy->isSigned() ||
2553 SrcTy->getPrimitiveSize() >= TD->getPointerSize()) {
2555 GEP.setOperand(i, Src);
2560 // If we are using a wider index than needed for this platform, shrink it
2561 // to what we need. If the incoming value needs a cast instruction,
2562 // insert it. This explicit cast can make subsequent optimizations more
2564 Value *Op = GEP.getOperand(i);
2565 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
2566 if (!isa<Constant>(Op)) {
2567 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
2568 Op->getName()), GEP);
2569 GEP.setOperand(i, Op);
2573 if (MadeChange) return &GEP;
2575 // Combine Indices - If the source pointer to this getelementptr instruction
2576 // is a getelementptr instruction, combine the indices of the two
2577 // getelementptr instructions into a single instruction.
2579 std::vector<Value*> SrcGEPOperands;
2580 if (GetElementPtrInst *Src = dyn_cast<GetElementPtrInst>(GEP.getOperand(0))) {
2581 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
2582 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GEP.getOperand(0))) {
2583 if (CE->getOpcode() == Instruction::GetElementPtr)
2584 SrcGEPOperands.assign(CE->op_begin(), CE->op_end());
2587 if (!SrcGEPOperands.empty()) {
2588 std::vector<Value *> Indices;
2590 // Can we combine the two pointer arithmetics offsets?
2591 if (SrcGEPOperands.size() == 2 && isa<Constant>(SrcGEPOperands[1]) &&
2592 isa<Constant>(GEP.getOperand(1))) {
2593 Constant *SGC = cast<Constant>(SrcGEPOperands[1]);
2594 Constant *GC = cast<Constant>(GEP.getOperand(1));
2595 if (SGC->getType() != GC->getType()) {
2596 SGC = ConstantExpr::getSignExtend(SGC, Type::LongTy);
2597 GC = ConstantExpr::getSignExtend(GC, Type::LongTy);
2600 // Replace: gep (gep %P, long C1), long C2, ...
2601 // With: gep %P, long (C1+C2), ...
2602 GEP.setOperand(0, SrcGEPOperands[0]);
2603 GEP.setOperand(1, ConstantExpr::getAdd(SGC, GC));
2604 if (Instruction *I = dyn_cast<Instruction>(GEP.getOperand(0)))
2605 AddUsersToWorkList(*I); // Reduce use count of Src
2607 } else if (SrcGEPOperands.size() == 2) {
2608 // Replace: gep (gep %P, long B), long A, ...
2609 // With: T = long A+B; gep %P, T, ...
2611 // Note that if our source is a gep chain itself that we wait for that
2612 // chain to be resolved before we perform this transformation. This
2613 // avoids us creating a TON of code in some cases.
2615 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
2616 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
2617 return 0; // Wait until our source is folded to completion.
2619 Value *Sum, *SO1 = SrcGEPOperands[1], *GO1 = GEP.getOperand(1);
2620 if (SO1 == Constant::getNullValue(SO1->getType())) {
2622 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
2625 // If they aren't the same type, convert both to an integer of the
2626 // target's pointer size.
2627 if (SO1->getType() != GO1->getType()) {
2628 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
2629 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
2630 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
2631 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
2633 unsigned PS = TD->getPointerSize();
2635 if (SO1->getType()->getPrimitiveSize() == PS) {
2636 // Convert GO1 to SO1's type.
2637 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
2639 } else if (GO1->getType()->getPrimitiveSize() == PS) {
2640 // Convert SO1 to GO1's type.
2641 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
2643 const Type *PT = TD->getIntPtrType();
2644 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
2645 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
2649 Sum = BinaryOperator::create(Instruction::Add, SO1, GO1,
2650 GEP.getOperand(0)->getName()+".sum", &GEP);
2651 WorkList.push_back(cast<Instruction>(Sum));
2653 GEP.setOperand(0, SrcGEPOperands[0]);
2654 GEP.setOperand(1, Sum);
2656 } else if (isa<Constant>(*GEP.idx_begin()) &&
2657 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
2658 SrcGEPOperands.size() != 1) {
2659 // Otherwise we can do the fold if the first index of the GEP is a zero
2660 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
2661 SrcGEPOperands.end());
2662 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
2663 } else if (SrcGEPOperands.back() ==
2664 Constant::getNullValue(SrcGEPOperands.back()->getType())) {
2665 // We have to check to make sure this really is an ARRAY index we are
2666 // ending up with, not a struct index.
2667 generic_gep_type_iterator<std::vector<Value*>::iterator>
2668 GTI = gep_type_begin(SrcGEPOperands[0]->getType(),
2669 SrcGEPOperands.begin()+1, SrcGEPOperands.end());
2670 std::advance(GTI, SrcGEPOperands.size()-2);
2671 if (isa<SequentialType>(*GTI)) {
2672 // If the src gep ends with a constant array index, merge this get into
2673 // it, even if we have a non-zero array index.
2674 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
2675 SrcGEPOperands.end()-1);
2676 Indices.insert(Indices.end(), GEP.idx_begin(), GEP.idx_end());
2680 if (!Indices.empty())
2681 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
2683 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(GEP.getOperand(0))) {
2684 // GEP of global variable. If all of the indices for this GEP are
2685 // constants, we can promote this to a constexpr instead of an instruction.
2687 // Scan for nonconstants...
2688 std::vector<Constant*> Indices;
2689 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
2690 for (; I != E && isa<Constant>(*I); ++I)
2691 Indices.push_back(cast<Constant>(*I));
2693 if (I == E) { // If they are all constants...
2695 ConstantExpr::getGetElementPtr(ConstantPointerRef::get(GV), Indices);
2697 // Replace all uses of the GEP with the new constexpr...
2698 return ReplaceInstUsesWith(GEP, CE);
2700 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GEP.getOperand(0))) {
2701 if (CE->getOpcode() == Instruction::Cast) {
2702 if (HasZeroPointerIndex) {
2703 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
2704 // into : GEP [10 x ubyte]* X, long 0, ...
2706 // This occurs when the program declares an array extern like "int X[];"
2708 Constant *X = CE->getOperand(0);
2709 const PointerType *CPTy = cast<PointerType>(CE->getType());
2710 if (const PointerType *XTy = dyn_cast<PointerType>(X->getType()))
2711 if (const ArrayType *XATy =
2712 dyn_cast<ArrayType>(XTy->getElementType()))
2713 if (const ArrayType *CATy =
2714 dyn_cast<ArrayType>(CPTy->getElementType()))
2715 if (CATy->getElementType() == XATy->getElementType()) {
2716 // At this point, we know that the cast source type is a pointer
2717 // to an array of the same type as the destination pointer
2718 // array. Because the array type is never stepped over (there
2719 // is a leading zero) we can fold the cast into this GEP.
2720 GEP.setOperand(0, X);
2730 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
2731 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
2732 if (AI.isArrayAllocation()) // Check C != 1
2733 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
2734 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
2735 AllocationInst *New = 0;
2737 // Create and insert the replacement instruction...
2738 if (isa<MallocInst>(AI))
2739 New = new MallocInst(NewTy, 0, AI.getName());
2741 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
2742 New = new AllocaInst(NewTy, 0, AI.getName());
2745 InsertNewInstBefore(New, AI);
2747 // Scan to the end of the allocation instructions, to skip over a block of
2748 // allocas if possible...
2750 BasicBlock::iterator It = New;
2751 while (isa<AllocationInst>(*It)) ++It;
2753 // Now that I is pointing to the first non-allocation-inst in the block,
2754 // insert our getelementptr instruction...
2756 std::vector<Value*> Idx(2, Constant::getNullValue(Type::IntTy));
2757 Value *V = new GetElementPtrInst(New, Idx, New->getName()+".sub", It);
2759 // Now make everything use the getelementptr instead of the original
2761 return ReplaceInstUsesWith(AI, V);
2764 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
2765 // Note that we only do this for alloca's, because malloc should allocate and
2766 // return a unique pointer, even for a zero byte allocation.
2767 if (isa<AllocaInst>(AI) && TD->getTypeSize(AI.getAllocatedType()) == 0)
2768 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
2773 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
2774 Value *Op = FI.getOperand(0);
2776 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
2777 if (CastInst *CI = dyn_cast<CastInst>(Op))
2778 if (isa<PointerType>(CI->getOperand(0)->getType())) {
2779 FI.setOperand(0, CI->getOperand(0));
2783 // If we have 'free null' delete the instruction. This can happen in stl code
2784 // when lots of inlining happens.
2785 if (isa<ConstantPointerNull>(Op))
2786 return EraseInstFromFunction(FI);
2792 /// GetGEPGlobalInitializer - Given a constant, and a getelementptr
2793 /// constantexpr, return the constant value being addressed by the constant
2794 /// expression, or null if something is funny.
2796 static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
2797 if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
2798 return 0; // Do not allow stepping over the value!
2800 // Loop over all of the operands, tracking down which value we are
2802 for (unsigned i = 2, e = CE->getNumOperands(); i != e; ++i)
2803 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(CE->getOperand(i))) {
2804 ConstantStruct *CS = dyn_cast<ConstantStruct>(C);
2805 if (CS == 0) return 0;
2806 if (CU->getValue() >= CS->getValues().size()) return 0;
2807 C = cast<Constant>(CS->getValues()[CU->getValue()]);
2808 } else if (ConstantSInt *CS = dyn_cast<ConstantSInt>(CE->getOperand(i))) {
2809 ConstantArray *CA = dyn_cast<ConstantArray>(C);
2810 if (CA == 0) return 0;
2811 if ((uint64_t)CS->getValue() >= CA->getValues().size()) return 0;
2812 C = cast<Constant>(CA->getValues()[CS->getValue()]);
2818 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
2819 Value *Op = LI.getOperand(0);
2820 if (LI.isVolatile()) return 0;
2822 if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(Op))
2823 Op = CPR->getValue();
2825 // Instcombine load (constant global) into the value loaded...
2826 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
2827 if (GV->isConstant() && !GV->isExternal())
2828 return ReplaceInstUsesWith(LI, GV->getInitializer());
2830 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded...
2831 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
2832 if (CE->getOpcode() == Instruction::GetElementPtr)
2833 if (ConstantPointerRef *G=dyn_cast<ConstantPointerRef>(CE->getOperand(0)))
2834 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(G->getValue()))
2835 if (GV->isConstant() && !GV->isExternal())
2836 if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
2837 return ReplaceInstUsesWith(LI, V);
2839 // load (cast X) --> cast (load X) iff safe
2840 if (CastInst *CI = dyn_cast<CastInst>(Op)) {
2841 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
2842 if (const PointerType *SrcTy =
2843 dyn_cast<PointerType>(CI->getOperand(0)->getType())) {
2844 const Type *SrcPTy = SrcTy->getElementType();
2845 if (TD->getTypeSize(SrcPTy) == TD->getTypeSize(DestPTy) &&
2846 (SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
2847 (DestPTy->isInteger() || isa<PointerType>(DestPTy))) {
2848 // Okay, we are casting from one integer or pointer type to another of
2849 // the same size. Instead of casting the pointer before the load, cast
2850 // the result of the loaded value.
2851 Value *NewLoad = InsertNewInstBefore(new LoadInst(CI->getOperand(0),
2852 CI->getName()), LI);
2853 // Now cast the result of the load.
2854 return new CastInst(NewLoad, LI.getType());
2863 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
2864 // Change br (not X), label True, label False to: br X, label False, True
2865 if (BI.isConditional() && !isa<Constant>(BI.getCondition())) {
2866 if (Value *V = dyn_castNotVal(BI.getCondition())) {
2867 BasicBlock *TrueDest = BI.getSuccessor(0);
2868 BasicBlock *FalseDest = BI.getSuccessor(1);
2869 // Swap Destinations and condition...
2871 BI.setSuccessor(0, FalseDest);
2872 BI.setSuccessor(1, TrueDest);
2874 } else if (SetCondInst *I = dyn_cast<SetCondInst>(BI.getCondition())) {
2875 // Cannonicalize setne -> seteq
2876 if ((I->getOpcode() == Instruction::SetNE ||
2877 I->getOpcode() == Instruction::SetLE ||
2878 I->getOpcode() == Instruction::SetGE) && I->hasOneUse()) {
2879 std::string Name = I->getName(); I->setName("");
2880 Instruction::BinaryOps NewOpcode =
2881 SetCondInst::getInverseCondition(I->getOpcode());
2882 Value *NewSCC = BinaryOperator::create(NewOpcode, I->getOperand(0),
2883 I->getOperand(1), Name, I);
2884 BasicBlock *TrueDest = BI.getSuccessor(0);
2885 BasicBlock *FalseDest = BI.getSuccessor(1);
2886 // Swap Destinations and condition...
2887 BI.setCondition(NewSCC);
2888 BI.setSuccessor(0, FalseDest);
2889 BI.setSuccessor(1, TrueDest);
2890 removeFromWorkList(I);
2891 I->getParent()->getInstList().erase(I);
2892 WorkList.push_back(cast<Instruction>(NewSCC));
2901 void InstCombiner::removeFromWorkList(Instruction *I) {
2902 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
2906 bool InstCombiner::runOnFunction(Function &F) {
2907 bool Changed = false;
2908 TD = &getAnalysis<TargetData>();
2910 WorkList.insert(WorkList.end(), inst_begin(F), inst_end(F));
2912 while (!WorkList.empty()) {
2913 Instruction *I = WorkList.back(); // Get an instruction from the worklist
2914 WorkList.pop_back();
2916 // Check to see if we can DCE or ConstantPropagate the instruction...
2917 // Check to see if we can DIE the instruction...
2918 if (isInstructionTriviallyDead(I)) {
2919 // Add operands to the worklist...
2920 if (I->getNumOperands() < 4)
2921 AddUsesToWorkList(*I);
2924 I->getParent()->getInstList().erase(I);
2925 removeFromWorkList(I);
2929 // Instruction isn't dead, see if we can constant propagate it...
2930 if (Constant *C = ConstantFoldInstruction(I)) {
2931 // Add operands to the worklist...
2932 AddUsesToWorkList(*I);
2933 ReplaceInstUsesWith(*I, C);
2936 I->getParent()->getInstList().erase(I);
2937 removeFromWorkList(I);
2941 // Check to see if any of the operands of this instruction are a
2942 // ConstantPointerRef. Since they sneak in all over the place and inhibit
2943 // optimization, we want to strip them out unconditionally!
2944 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
2945 if (ConstantPointerRef *CPR =
2946 dyn_cast<ConstantPointerRef>(I->getOperand(i))) {
2947 I->setOperand(i, CPR->getValue());
2951 // Now that we have an instruction, try combining it to simplify it...
2952 if (Instruction *Result = visit(*I)) {
2954 // Should we replace the old instruction with a new one?
2956 DEBUG(std::cerr << "IC: Old = " << *I
2957 << " New = " << *Result);
2959 // Instructions can end up on the worklist more than once. Make sure
2960 // we do not process an instruction that has been deleted.
2961 removeFromWorkList(I);
2963 // Move the name to the new instruction first...
2964 std::string OldName = I->getName(); I->setName("");
2965 Result->setName(OldName);
2967 // Insert the new instruction into the basic block...
2968 BasicBlock *InstParent = I->getParent();
2969 InstParent->getInstList().insert(I, Result);
2971 // Everything uses the new instruction now...
2972 I->replaceAllUsesWith(Result);
2974 // Erase the old instruction.
2975 InstParent->getInstList().erase(I);
2977 DEBUG(std::cerr << "IC: MOD = " << *I);
2979 BasicBlock::iterator II = I;
2981 // If the instruction was modified, it's possible that it is now dead.
2982 // if so, remove it.
2983 if (dceInstruction(II)) {
2984 // Instructions may end up in the worklist more than once. Erase them
2986 removeFromWorkList(I);
2992 WorkList.push_back(Result);
2993 AddUsersToWorkList(*Result);
3002 Pass *llvm::createInstructionCombiningPass() {
3003 return new InstCombiner();