1 //===- InstructionCombining.cpp - Combine multiple instructions -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // InstructionCombining - Combine instructions to form fewer, simple
11 // instructions. This pass does not modify the CFG This pass is where algebraic
12 // simplification happens.
14 // This pass combines things like:
20 // This is a simple worklist driven algorithm.
22 // This pass guarantees that the following canonicalizations are performed on
24 // 1. If a binary operator has a constant operand, it is moved to the RHS
25 // 2. Bitwise operators with constant operands are always grouped so that
26 // shifts are performed first, then or's, then and's, then xor's.
27 // 3. SetCC instructions are converted from <,>,<=,>= to ==,!= if possible
28 // 4. All SetCC instructions on boolean values are replaced with logical ops
29 // 5. add X, X is represented as (X*2) => (X << 1)
30 // 6. Multiplies with a power-of-two constant argument are transformed into
32 // N. This list is incomplete
34 //===----------------------------------------------------------------------===//
36 #define DEBUG_TYPE "instcombine"
37 #include "llvm/Transforms/Scalar.h"
38 #include "llvm/Instructions.h"
39 #include "llvm/Intrinsics.h"
40 #include "llvm/Pass.h"
41 #include "llvm/Constants.h"
42 #include "llvm/DerivedTypes.h"
43 #include "llvm/GlobalVariable.h"
44 #include "llvm/Target/TargetData.h"
45 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
46 #include "llvm/Transforms/Utils/Local.h"
47 #include "llvm/Support/CallSite.h"
48 #include "llvm/Support/GetElementPtrTypeIterator.h"
49 #include "llvm/Support/InstIterator.h"
50 #include "llvm/Support/InstVisitor.h"
51 #include "llvm/Support/PatternMatch.h"
52 #include "llvm/Support/Debug.h"
53 #include "llvm/ADT/Statistic.h"
56 using namespace llvm::PatternMatch;
59 Statistic<> NumCombined ("instcombine", "Number of insts combined");
60 Statistic<> NumConstProp("instcombine", "Number of constant folds");
61 Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
63 class InstCombiner : public FunctionPass,
64 public InstVisitor<InstCombiner, Instruction*> {
65 // Worklist of all of the instructions that need to be simplified.
66 std::vector<Instruction*> WorkList;
69 /// AddUsersToWorkList - When an instruction is simplified, add all users of
70 /// the instruction to the work lists because they might get more simplified
73 void AddUsersToWorkList(Instruction &I) {
74 for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
76 WorkList.push_back(cast<Instruction>(*UI));
79 /// AddUsesToWorkList - When an instruction is simplified, add operands to
80 /// the work lists because they might get more simplified now.
82 void AddUsesToWorkList(Instruction &I) {
83 for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
84 if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
85 WorkList.push_back(Op);
88 // removeFromWorkList - remove all instances of I from the worklist.
89 void removeFromWorkList(Instruction *I);
91 virtual bool runOnFunction(Function &F);
93 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
94 AU.addRequired<TargetData>();
98 TargetData &getTargetData() const { return *TD; }
100 // Visitation implementation - Implement instruction combining for different
101 // instruction types. The semantics are as follows:
103 // null - No change was made
104 // I - Change was made, I is still valid, I may be dead though
105 // otherwise - Change was made, replace I with returned instruction
107 Instruction *visitAdd(BinaryOperator &I);
108 Instruction *visitSub(BinaryOperator &I);
109 Instruction *visitMul(BinaryOperator &I);
110 Instruction *visitDiv(BinaryOperator &I);
111 Instruction *visitRem(BinaryOperator &I);
112 Instruction *visitAnd(BinaryOperator &I);
113 Instruction *visitOr (BinaryOperator &I);
114 Instruction *visitXor(BinaryOperator &I);
115 Instruction *visitSetCondInst(BinaryOperator &I);
116 Instruction *visitShiftInst(ShiftInst &I);
117 Instruction *visitCastInst(CastInst &CI);
118 Instruction *visitSelectInst(SelectInst &CI);
119 Instruction *visitCallInst(CallInst &CI);
120 Instruction *visitInvokeInst(InvokeInst &II);
121 Instruction *visitPHINode(PHINode &PN);
122 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
123 Instruction *visitAllocationInst(AllocationInst &AI);
124 Instruction *visitFreeInst(FreeInst &FI);
125 Instruction *visitLoadInst(LoadInst &LI);
126 Instruction *visitBranchInst(BranchInst &BI);
127 Instruction *visitSwitchInst(SwitchInst &SI);
129 // visitInstruction - Specify what to return for unhandled instructions...
130 Instruction *visitInstruction(Instruction &I) { return 0; }
133 Instruction *visitCallSite(CallSite CS);
134 bool transformConstExprCastCall(CallSite CS);
137 // InsertNewInstBefore - insert an instruction New before instruction Old
138 // in the program. Add the new instruction to the worklist.
140 Value *InsertNewInstBefore(Instruction *New, Instruction &Old) {
141 assert(New && New->getParent() == 0 &&
142 "New instruction already inserted into a basic block!");
143 BasicBlock *BB = Old.getParent();
144 BB->getInstList().insert(&Old, New); // Insert inst
145 WorkList.push_back(New); // Add to worklist
149 // ReplaceInstUsesWith - This method is to be used when an instruction is
150 // found to be dead, replacable with another preexisting expression. Here
151 // we add all uses of I to the worklist, replace all uses of I with the new
152 // value, then return I, so that the inst combiner will know that I was
155 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
156 AddUsersToWorkList(I); // Add all modified instrs to worklist
158 I.replaceAllUsesWith(V);
161 // If we are replacing the instruction with itself, this must be in a
162 // segment of unreachable code, so just clobber the instruction.
163 I.replaceAllUsesWith(Constant::getNullValue(I.getType()));
168 // EraseInstFromFunction - When dealing with an instruction that has side
169 // effects or produces a void value, we can't rely on DCE to delete the
170 // instruction. Instead, visit methods should return the value returned by
172 Instruction *EraseInstFromFunction(Instruction &I) {
173 assert(I.use_empty() && "Cannot erase instruction that is used!");
174 AddUsesToWorkList(I);
175 removeFromWorkList(&I);
176 I.getParent()->getInstList().erase(&I);
177 return 0; // Don't do anything with FI
182 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
183 /// InsertBefore instruction. This is specialized a bit to avoid inserting
184 /// casts that are known to not do anything...
186 Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
187 Instruction *InsertBefore);
189 // SimplifyCommutative - This performs a few simplifications for commutative
191 bool SimplifyCommutative(BinaryOperator &I);
193 Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
194 ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
197 RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
200 // getComplexity: Assign a complexity or rank value to LLVM Values...
201 // 0 -> Constant, 1 -> Other, 2 -> Argument, 2 -> Unary, 3 -> OtherInst
202 static unsigned getComplexity(Value *V) {
203 if (isa<Instruction>(V)) {
204 if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
208 if (isa<Argument>(V)) return 2;
209 return isa<Constant>(V) ? 0 : 1;
212 // isOnlyUse - Return true if this instruction will be deleted if we stop using
214 static bool isOnlyUse(Value *V) {
215 return V->hasOneUse() || isa<Constant>(V);
218 // getPromotedType - Return the specified type promoted as it would be to pass
219 // though a va_arg area...
220 static const Type *getPromotedType(const Type *Ty) {
221 switch (Ty->getTypeID()) {
222 case Type::SByteTyID:
223 case Type::ShortTyID: return Type::IntTy;
224 case Type::UByteTyID:
225 case Type::UShortTyID: return Type::UIntTy;
226 case Type::FloatTyID: return Type::DoubleTy;
231 // SimplifyCommutative - This performs a few simplifications for commutative
234 // 1. Order operands such that they are listed from right (least complex) to
235 // left (most complex). This puts constants before unary operators before
238 // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
239 // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
241 bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
242 bool Changed = false;
243 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
244 Changed = !I.swapOperands();
246 if (!I.isAssociative()) return Changed;
247 Instruction::BinaryOps Opcode = I.getOpcode();
248 if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
249 if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
250 if (isa<Constant>(I.getOperand(1))) {
251 Constant *Folded = ConstantExpr::get(I.getOpcode(),
252 cast<Constant>(I.getOperand(1)),
253 cast<Constant>(Op->getOperand(1)));
254 I.setOperand(0, Op->getOperand(0));
255 I.setOperand(1, Folded);
257 } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
258 if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
259 isOnlyUse(Op) && isOnlyUse(Op1)) {
260 Constant *C1 = cast<Constant>(Op->getOperand(1));
261 Constant *C2 = cast<Constant>(Op1->getOperand(1));
263 // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
264 Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
265 Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
268 WorkList.push_back(New);
269 I.setOperand(0, New);
270 I.setOperand(1, Folded);
277 // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
278 // if the LHS is a constant zero (which is the 'negate' form).
280 static inline Value *dyn_castNegVal(Value *V) {
281 if (BinaryOperator::isNeg(V))
282 return BinaryOperator::getNegArgument(cast<BinaryOperator>(V));
284 // Constants can be considered to be negated values if they can be folded...
285 if (Constant *C = dyn_cast<Constant>(V))
286 return ConstantExpr::getNeg(C);
290 static inline Value *dyn_castNotVal(Value *V) {
291 if (BinaryOperator::isNot(V))
292 return BinaryOperator::getNotArgument(cast<BinaryOperator>(V));
294 // Constants can be considered to be not'ed values...
295 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
296 return ConstantExpr::getNot(C);
300 // dyn_castFoldableMul - If this value is a multiply that can be folded into
301 // other computations (because it has a constant operand), return the
302 // non-constant operand of the multiply.
304 static inline Value *dyn_castFoldableMul(Value *V) {
305 if (V->hasOneUse() && V->getType()->isInteger())
306 if (Instruction *I = dyn_cast<Instruction>(V))
307 if (I->getOpcode() == Instruction::Mul)
308 if (isa<Constant>(I->getOperand(1)))
309 return I->getOperand(0);
313 // Log2 - Calculate the log base 2 for the specified value if it is exactly a
315 static unsigned Log2(uint64_t Val) {
316 assert(Val > 1 && "Values 0 and 1 should be handled elsewhere!");
319 if (Val & 1) return 0; // Multiple bits set?
327 /// AssociativeOpt - Perform an optimization on an associative operator. This
328 /// function is designed to check a chain of associative operators for a
329 /// potential to apply a certain optimization. Since the optimization may be
330 /// applicable if the expression was reassociated, this checks the chain, then
331 /// reassociates the expression as necessary to expose the optimization
332 /// opportunity. This makes use of a special Functor, which must define
333 /// 'shouldApply' and 'apply' methods.
335 template<typename Functor>
336 Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
337 unsigned Opcode = Root.getOpcode();
338 Value *LHS = Root.getOperand(0);
340 // Quick check, see if the immediate LHS matches...
341 if (F.shouldApply(LHS))
342 return F.apply(Root);
344 // Otherwise, if the LHS is not of the same opcode as the root, return.
345 Instruction *LHSI = dyn_cast<Instruction>(LHS);
346 while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
347 // Should we apply this transform to the RHS?
348 bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
350 // If not to the RHS, check to see if we should apply to the LHS...
351 if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
352 cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
356 // If the functor wants to apply the optimization to the RHS of LHSI,
357 // reassociate the expression from ((? op A) op B) to (? op (A op B))
359 BasicBlock *BB = Root.getParent();
361 // Now all of the instructions are in the current basic block, go ahead
362 // and perform the reassociation.
363 Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
365 // First move the selected RHS to the LHS of the root...
366 Root.setOperand(0, LHSI->getOperand(1));
368 // Make what used to be the LHS of the root be the user of the root...
369 Value *ExtraOperand = TmpLHSI->getOperand(1);
370 if (&Root == TmpLHSI) {
371 Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
374 Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
375 TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
376 TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
377 BasicBlock::iterator ARI = &Root; ++ARI;
378 BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
381 // Now propagate the ExtraOperand down the chain of instructions until we
383 while (TmpLHSI != LHSI) {
384 Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
385 // Move the instruction to immediately before the chain we are
386 // constructing to avoid breaking dominance properties.
387 NextLHSI->getParent()->getInstList().remove(NextLHSI);
388 BB->getInstList().insert(ARI, NextLHSI);
391 Value *NextOp = NextLHSI->getOperand(1);
392 NextLHSI->setOperand(1, ExtraOperand);
394 ExtraOperand = NextOp;
397 // Now that the instructions are reassociated, have the functor perform
398 // the transformation...
399 return F.apply(Root);
402 LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
408 // AddRHS - Implements: X + X --> X << 1
411 AddRHS(Value *rhs) : RHS(rhs) {}
412 bool shouldApply(Value *LHS) const { return LHS == RHS; }
413 Instruction *apply(BinaryOperator &Add) const {
414 return new ShiftInst(Instruction::Shl, Add.getOperand(0),
415 ConstantInt::get(Type::UByteTy, 1));
419 // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
421 struct AddMaskingAnd {
423 AddMaskingAnd(Constant *c) : C2(c) {}
424 bool shouldApply(Value *LHS) const {
426 return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
427 ConstantExpr::getAnd(C1, C2)->isNullValue();
429 Instruction *apply(BinaryOperator &Add) const {
430 return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
434 static Value *FoldOperationIntoSelectOperand(Instruction &BI, Value *SO,
436 // Figure out if the constant is the left or the right argument.
437 bool ConstIsRHS = isa<Constant>(BI.getOperand(1));
438 Constant *ConstOperand = cast<Constant>(BI.getOperand(ConstIsRHS));
440 if (Constant *SOC = dyn_cast<Constant>(SO)) {
442 return ConstantExpr::get(BI.getOpcode(), SOC, ConstOperand);
443 return ConstantExpr::get(BI.getOpcode(), ConstOperand, SOC);
446 Value *Op0 = SO, *Op1 = ConstOperand;
450 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&BI))
451 New = BinaryOperator::create(BO->getOpcode(), Op0, Op1);
452 else if (ShiftInst *SI = dyn_cast<ShiftInst>(&BI))
453 New = new ShiftInst(SI->getOpcode(), Op0, Op1);
455 assert(0 && "Unknown binary instruction type!");
458 return IC->InsertNewInstBefore(New, BI);
461 // FoldBinOpIntoSelect - Given an instruction with a select as one operand and a
462 // constant as the other operand, try to fold the binary operator into the
464 static Instruction *FoldBinOpIntoSelect(Instruction &BI, SelectInst *SI,
466 // Don't modify shared select instructions
467 if (!SI->hasOneUse()) return 0;
468 Value *TV = SI->getOperand(1);
469 Value *FV = SI->getOperand(2);
471 if (isa<Constant>(TV) || isa<Constant>(FV)) {
472 Value *SelectTrueVal = FoldOperationIntoSelectOperand(BI, TV, IC);
473 Value *SelectFalseVal = FoldOperationIntoSelectOperand(BI, FV, IC);
475 return new SelectInst(SI->getCondition(), SelectTrueVal,
481 Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
482 bool Changed = SimplifyCommutative(I);
483 Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
485 if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
487 if (!I.getType()->isFloatingPoint() && // -0 + +0 = +0, so it's not a noop
489 return ReplaceInstUsesWith(I, LHS);
491 // X + (signbit) --> X ^ signbit
492 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
493 unsigned NumBits = CI->getType()->getPrimitiveSize()*8;
494 uint64_t Val = CI->getRawValue() & (1ULL << NumBits)-1;
495 if (Val == (1ULL << NumBits-1))
496 return BinaryOperator::createXor(LHS, RHS);
501 if (I.getType()->isInteger()) {
502 if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
506 if (Value *V = dyn_castNegVal(LHS))
507 return BinaryOperator::createSub(RHS, V);
510 if (!isa<Constant>(RHS))
511 if (Value *V = dyn_castNegVal(RHS))
512 return BinaryOperator::createSub(LHS, V);
514 // X*C + X --> X * (C+1)
515 if (dyn_castFoldableMul(LHS) == RHS) {
517 ConstantExpr::getAdd(
518 cast<Constant>(cast<Instruction>(LHS)->getOperand(1)),
519 ConstantInt::get(I.getType(), 1));
520 return BinaryOperator::createMul(RHS, CP1);
523 // X + X*C --> X * (C+1)
524 if (dyn_castFoldableMul(RHS) == LHS) {
526 ConstantExpr::getAdd(
527 cast<Constant>(cast<Instruction>(RHS)->getOperand(1)),
528 ConstantInt::get(I.getType(), 1));
529 return BinaryOperator::createMul(LHS, CP1);
532 // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
534 if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
535 if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
537 if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
539 if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
540 Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
541 return BinaryOperator::createSub(C, X);
544 // Try to fold constant add into select arguments.
545 if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
546 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
550 return Changed ? &I : 0;
553 // isSignBit - Return true if the value represented by the constant only has the
554 // highest order bit set.
555 static bool isSignBit(ConstantInt *CI) {
556 unsigned NumBits = CI->getType()->getPrimitiveSize()*8;
557 return (CI->getRawValue() & ~(-1LL << NumBits)) == (1ULL << (NumBits-1));
560 static unsigned getTypeSizeInBits(const Type *Ty) {
561 return Ty == Type::BoolTy ? 1 : Ty->getPrimitiveSize()*8;
564 /// RemoveNoopCast - Strip off nonconverting casts from the value.
566 static Value *RemoveNoopCast(Value *V) {
567 if (CastInst *CI = dyn_cast<CastInst>(V)) {
568 const Type *CTy = CI->getType();
569 const Type *OpTy = CI->getOperand(0)->getType();
570 if (CTy->isInteger() && OpTy->isInteger()) {
571 if (CTy->getPrimitiveSize() == OpTy->getPrimitiveSize())
572 return RemoveNoopCast(CI->getOperand(0));
573 } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
574 return RemoveNoopCast(CI->getOperand(0));
579 Instruction *InstCombiner::visitSub(BinaryOperator &I) {
580 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
582 if (Op0 == Op1) // sub X, X -> 0
583 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
585 // If this is a 'B = x-(-A)', change to B = x+A...
586 if (Value *V = dyn_castNegVal(Op1))
587 return BinaryOperator::createAdd(Op0, V);
589 if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
590 // Replace (-1 - A) with (~A)...
591 if (C->isAllOnesValue())
592 return BinaryOperator::createNot(Op1);
594 // C - ~X == X + (1+C)
596 if (match(Op1, m_Not(m_Value(X))))
597 return BinaryOperator::createAdd(X,
598 ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
599 // -((uint)X >> 31) -> ((int)X >> 31)
600 // -((int)X >> 31) -> ((uint)X >> 31)
601 if (C->isNullValue()) {
602 Value *NoopCastedRHS = RemoveNoopCast(Op1);
603 if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
604 if (SI->getOpcode() == Instruction::Shr)
605 if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
607 if (SI->getType()->isSigned())
608 NewTy = SI->getType()->getUnsignedVersion();
610 NewTy = SI->getType()->getSignedVersion();
611 // Check to see if we are shifting out everything but the sign bit.
612 if (CU->getValue() == SI->getType()->getPrimitiveSize()*8-1) {
613 // Ok, the transformation is safe. Insert a cast of the incoming
614 // value, then the new shift, then the new cast.
615 Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
616 SI->getOperand(0)->getName());
617 Value *InV = InsertNewInstBefore(FirstCast, I);
618 Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
620 if (NewShift->getType() == I.getType())
623 InV = InsertNewInstBefore(NewShift, I);
624 return new CastInst(NewShift, I.getType());
630 // Try to fold constant sub into select arguments.
631 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
632 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
636 if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1))
637 if (Op1I->hasOneUse()) {
638 // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
639 // is not used by anyone else...
641 if (Op1I->getOpcode() == Instruction::Sub &&
642 !Op1I->getType()->isFloatingPoint()) {
643 // Swap the two operands of the subexpr...
644 Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
645 Op1I->setOperand(0, IIOp1);
646 Op1I->setOperand(1, IIOp0);
648 // Create the new top level add instruction...
649 return BinaryOperator::createAdd(Op0, Op1);
652 // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
654 if (Op1I->getOpcode() == Instruction::And &&
655 (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
656 Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
659 InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
660 return BinaryOperator::createAnd(Op0, NewNot);
663 // X - X*C --> X * (1-C)
664 if (dyn_castFoldableMul(Op1I) == Op0) {
666 ConstantExpr::getSub(ConstantInt::get(I.getType(), 1),
667 cast<Constant>(cast<Instruction>(Op1)->getOperand(1)));
668 assert(CP1 && "Couldn't constant fold 1-C?");
669 return BinaryOperator::createMul(Op0, CP1);
673 // X*C - X --> X * (C-1)
674 if (dyn_castFoldableMul(Op0) == Op1) {
676 ConstantExpr::getSub(cast<Constant>(cast<Instruction>(Op0)->getOperand(1)),
677 ConstantInt::get(I.getType(), 1));
678 assert(CP1 && "Couldn't constant fold C - 1?");
679 return BinaryOperator::createMul(Op1, CP1);
685 /// isSignBitCheck - Given an exploded setcc instruction, return true if it is
686 /// really just returns true if the most significant (sign) bit is set.
687 static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
688 if (RHS->getType()->isSigned()) {
689 // True if source is LHS < 0 or LHS <= -1
690 return Opcode == Instruction::SetLT && RHS->isNullValue() ||
691 Opcode == Instruction::SetLE && RHS->isAllOnesValue();
693 ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
694 // True if source is LHS > 127 or LHS >= 128, where the constants depend on
695 // the size of the integer type.
696 if (Opcode == Instruction::SetGE)
697 return RHSC->getValue() == 1ULL<<(RHS->getType()->getPrimitiveSize()*8-1);
698 if (Opcode == Instruction::SetGT)
699 return RHSC->getValue() ==
700 (1ULL << (RHS->getType()->getPrimitiveSize()*8-1))-1;
705 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
706 bool Changed = SimplifyCommutative(I);
707 Value *Op0 = I.getOperand(0);
709 // Simplify mul instructions with a constant RHS...
710 if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
711 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
713 // ((X << C1)*C2) == (X * (C2 << C1))
714 if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0))
715 if (SI->getOpcode() == Instruction::Shl)
716 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
717 return BinaryOperator::createMul(SI->getOperand(0),
718 ConstantExpr::getShl(CI, ShOp));
720 if (CI->isNullValue())
721 return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
722 if (CI->equalsInt(1)) // X * 1 == X
723 return ReplaceInstUsesWith(I, Op0);
724 if (CI->isAllOnesValue()) // X * -1 == 0 - X
725 return BinaryOperator::createNeg(Op0, I.getName());
727 int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
728 if (uint64_t C = Log2(Val)) // Replace X*(2^C) with X << C
729 return new ShiftInst(Instruction::Shl, Op0,
730 ConstantUInt::get(Type::UByteTy, C));
731 } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
732 if (Op1F->isNullValue())
733 return ReplaceInstUsesWith(I, Op1);
735 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
736 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
737 if (Op1F->getValue() == 1.0)
738 return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
741 // Try to fold constant mul into select arguments.
742 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
743 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
747 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
748 if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
749 return BinaryOperator::createMul(Op0v, Op1v);
751 // If one of the operands of the multiply is a cast from a boolean value, then
752 // we know the bool is either zero or one, so this is a 'masking' multiply.
753 // See if we can simplify things based on how the boolean was originally
755 CastInst *BoolCast = 0;
756 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
757 if (CI->getOperand(0)->getType() == Type::BoolTy)
760 if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
761 if (CI->getOperand(0)->getType() == Type::BoolTy)
764 if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
765 Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
766 const Type *SCOpTy = SCIOp0->getType();
768 // If the setcc is true iff the sign bit of X is set, then convert this
769 // multiply into a shift/and combination.
770 if (isa<ConstantInt>(SCIOp1) &&
771 isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
772 // Shift the X value right to turn it into "all signbits".
773 Constant *Amt = ConstantUInt::get(Type::UByteTy,
774 SCOpTy->getPrimitiveSize()*8-1);
775 if (SCIOp0->getType()->isUnsigned()) {
776 const Type *NewTy = SCIOp0->getType()->getSignedVersion();
777 SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
778 SCIOp0->getName()), I);
782 InsertNewInstBefore(new ShiftInst(Instruction::Shr, SCIOp0, Amt,
783 BoolCast->getOperand(0)->getName()+
786 // If the multiply type is not the same as the source type, sign extend
787 // or truncate to the multiply type.
788 if (I.getType() != V->getType())
789 V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
791 Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
792 return BinaryOperator::createAnd(V, OtherOp);
797 return Changed ? &I : 0;
800 Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
801 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
803 if (RHS->equalsInt(1))
804 return ReplaceInstUsesWith(I, I.getOperand(0));
807 if (RHS->isAllOnesValue())
808 return BinaryOperator::createNeg(I.getOperand(0));
810 // Check to see if this is an unsigned division with an exact power of 2,
811 // if so, convert to a right shift.
812 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
813 if (uint64_t Val = C->getValue()) // Don't break X / 0
814 if (uint64_t C = Log2(Val))
815 return new ShiftInst(Instruction::Shr, I.getOperand(0),
816 ConstantUInt::get(Type::UByteTy, C));
819 // 0 / X == 0, we don't need to preserve faults!
820 if (ConstantInt *LHS = dyn_cast<ConstantInt>(I.getOperand(0)))
821 if (LHS->equalsInt(0))
822 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
828 Instruction *InstCombiner::visitRem(BinaryOperator &I) {
829 if (I.getType()->isSigned())
830 if (Value *RHSNeg = dyn_castNegVal(I.getOperand(1)))
831 if (!isa<ConstantSInt>(RHSNeg) ||
832 cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
834 AddUsesToWorkList(I);
835 I.setOperand(1, RHSNeg);
839 if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
840 if (RHS->equalsInt(1)) // X % 1 == 0
841 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
843 // Check to see if this is an unsigned remainder with an exact power of 2,
844 // if so, convert to a bitwise and.
845 if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
846 if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
847 if (!(Val & (Val-1))) // Power of 2
848 return BinaryOperator::createAnd(I.getOperand(0),
849 ConstantUInt::get(I.getType(), Val-1));
852 // 0 % X == 0, we don't need to preserve faults!
853 if (ConstantInt *LHS = dyn_cast<ConstantInt>(I.getOperand(0)))
854 if (LHS->equalsInt(0))
855 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
860 // isMaxValueMinusOne - return true if this is Max-1
861 static bool isMaxValueMinusOne(const ConstantInt *C) {
862 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
863 // Calculate -1 casted to the right type...
864 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
865 uint64_t Val = ~0ULL; // All ones
866 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
867 return CU->getValue() == Val-1;
870 const ConstantSInt *CS = cast<ConstantSInt>(C);
872 // Calculate 0111111111..11111
873 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
874 int64_t Val = INT64_MAX; // All ones
875 Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
876 return CS->getValue() == Val-1;
879 // isMinValuePlusOne - return true if this is Min+1
880 static bool isMinValuePlusOne(const ConstantInt *C) {
881 if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
882 return CU->getValue() == 1;
884 const ConstantSInt *CS = cast<ConstantSInt>(C);
886 // Calculate 1111111111000000000000
887 unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
888 int64_t Val = -1; // All ones
889 Val <<= TypeBits-1; // Shift over to the right spot
890 return CS->getValue() == Val+1;
893 // isOneBitSet - Return true if there is exactly one bit set in the specified
895 static bool isOneBitSet(const ConstantInt *CI) {
896 uint64_t V = CI->getRawValue();
897 return V && (V & (V-1)) == 0;
900 /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
901 /// are carefully arranged to allow folding of expressions such as:
903 /// (A < B) | (A > B) --> (A != B)
905 /// Bit value '4' represents that the comparison is true if A > B, bit value '2'
906 /// represents that the comparison is true if A == B, and bit value '1' is true
909 static unsigned getSetCondCode(const SetCondInst *SCI) {
910 switch (SCI->getOpcode()) {
912 case Instruction::SetGT: return 1;
913 case Instruction::SetEQ: return 2;
914 case Instruction::SetGE: return 3;
915 case Instruction::SetLT: return 4;
916 case Instruction::SetNE: return 5;
917 case Instruction::SetLE: return 6;
920 assert(0 && "Invalid SetCC opcode!");
925 /// getSetCCValue - This is the complement of getSetCondCode, which turns an
926 /// opcode and two operands into either a constant true or false, or a brand new
927 /// SetCC instruction.
928 static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
930 case 0: return ConstantBool::False;
931 case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
932 case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
933 case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
934 case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
935 case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
936 case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
937 case 7: return ConstantBool::True;
938 default: assert(0 && "Illegal SetCCCode!"); return 0;
942 // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
943 struct FoldSetCCLogical {
946 FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
947 : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
948 bool shouldApply(Value *V) const {
949 if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
950 return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
951 SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
954 Instruction *apply(BinaryOperator &Log) const {
955 SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
956 if (SCI->getOperand(0) != LHS) {
957 assert(SCI->getOperand(1) == LHS);
958 SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
961 unsigned LHSCode = getSetCondCode(SCI);
962 unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
964 switch (Log.getOpcode()) {
965 case Instruction::And: Code = LHSCode & RHSCode; break;
966 case Instruction::Or: Code = LHSCode | RHSCode; break;
967 case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
968 default: assert(0 && "Illegal logical opcode!"); return 0;
971 Value *RV = getSetCCValue(Code, LHS, RHS);
972 if (Instruction *I = dyn_cast<Instruction>(RV))
974 // Otherwise, it's a constant boolean value...
975 return IC.ReplaceInstUsesWith(Log, RV);
980 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
981 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
982 // guaranteed to be either a shift instruction or a binary operator.
983 Instruction *InstCombiner::OptAndOp(Instruction *Op,
984 ConstantIntegral *OpRHS,
985 ConstantIntegral *AndRHS,
986 BinaryOperator &TheAnd) {
987 Value *X = Op->getOperand(0);
988 Constant *Together = 0;
989 if (!isa<ShiftInst>(Op))
990 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
992 switch (Op->getOpcode()) {
993 case Instruction::Xor:
994 if (Together->isNullValue()) {
995 // (X ^ C1) & C2 --> (X & C2) iff (C1&C2) == 0
996 return BinaryOperator::createAnd(X, AndRHS);
997 } else if (Op->hasOneUse()) {
998 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
999 std::string OpName = Op->getName(); Op->setName("");
1000 Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
1001 InsertNewInstBefore(And, TheAnd);
1002 return BinaryOperator::createXor(And, Together);
1005 case Instruction::Or:
1006 // (X | C1) & C2 --> X & C2 iff C1 & C1 == 0
1007 if (Together->isNullValue())
1008 return BinaryOperator::createAnd(X, AndRHS);
1010 if (Together == AndRHS) // (X | C) & C --> C
1011 return ReplaceInstUsesWith(TheAnd, AndRHS);
1013 if (Op->hasOneUse() && Together != OpRHS) {
1014 // (X | C1) & C2 --> (X | (C1&C2)) & C2
1015 std::string Op0Name = Op->getName(); Op->setName("");
1016 Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
1017 InsertNewInstBefore(Or, TheAnd);
1018 return BinaryOperator::createAnd(Or, AndRHS);
1022 case Instruction::Add:
1023 if (Op->hasOneUse()) {
1024 // Adding a one to a single bit bit-field should be turned into an XOR
1025 // of the bit. First thing to check is to see if this AND is with a
1026 // single bit constant.
1027 uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
1029 // Clear bits that are not part of the constant.
1030 AndRHSV &= (1ULL << AndRHS->getType()->getPrimitiveSize()*8)-1;
1032 // If there is only one bit set...
1033 if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
1034 // Ok, at this point, we know that we are masking the result of the
1035 // ADD down to exactly one bit. If the constant we are adding has
1036 // no bits set below this bit, then we can eliminate the ADD.
1037 uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
1039 // Check to see if any bits below the one bit set in AndRHSV are set.
1040 if ((AddRHS & (AndRHSV-1)) == 0) {
1041 // If not, the only thing that can effect the output of the AND is
1042 // the bit specified by AndRHSV. If that bit is set, the effect of
1043 // the XOR is to toggle the bit. If it is clear, then the ADD has
1045 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
1046 TheAnd.setOperand(0, X);
1049 std::string Name = Op->getName(); Op->setName("");
1050 // Pull the XOR out of the AND.
1051 Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
1052 InsertNewInstBefore(NewAnd, TheAnd);
1053 return BinaryOperator::createXor(NewAnd, AndRHS);
1060 case Instruction::Shl: {
1061 // We know that the AND will not produce any of the bits shifted in, so if
1062 // the anded constant includes them, clear them now!
1064 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1065 Constant *CI = ConstantExpr::getAnd(AndRHS,
1066 ConstantExpr::getShl(AllOne, OpRHS));
1068 TheAnd.setOperand(1, CI);
1073 case Instruction::Shr:
1074 // We know that the AND will not produce any of the bits shifted in, so if
1075 // the anded constant includes them, clear them now! This only applies to
1076 // unsigned shifts, because a signed shr may bring in set bits!
1078 if (AndRHS->getType()->isUnsigned()) {
1079 Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
1080 Constant *CI = ConstantExpr::getAnd(AndRHS,
1081 ConstantExpr::getShr(AllOne, OpRHS));
1083 TheAnd.setOperand(1, CI);
1093 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1094 bool Changed = SimplifyCommutative(I);
1095 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1097 // and X, X = X and X, 0 == 0
1098 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
1099 return ReplaceInstUsesWith(I, Op1);
1102 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1103 if (RHS->isAllOnesValue())
1104 return ReplaceInstUsesWith(I, Op0);
1106 // Optimize a variety of ((val OP C1) & C2) combinations...
1107 if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
1108 Instruction *Op0I = cast<Instruction>(Op0);
1109 Value *X = Op0I->getOperand(0);
1110 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1111 if (Instruction *Res = OptAndOp(Op0I, Op0CI, RHS, I))
1115 // Try to fold constant and into select arguments.
1116 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1117 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1121 Value *Op0NotVal = dyn_castNotVal(Op0);
1122 Value *Op1NotVal = dyn_castNotVal(Op1);
1124 if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
1125 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1127 // (~A & ~B) == (~(A | B)) - De Morgan's Law
1128 if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1129 Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
1130 I.getName()+".demorgan");
1131 InsertNewInstBefore(Or, I);
1132 return BinaryOperator::createNot(Or);
1135 // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
1136 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
1137 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1140 return Changed ? &I : 0;
1145 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
1146 bool Changed = SimplifyCommutative(I);
1147 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1149 // or X, X = X or X, 0 == X
1150 if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
1151 return ReplaceInstUsesWith(I, Op0);
1154 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1155 if (RHS->isAllOnesValue())
1156 return ReplaceInstUsesWith(I, Op1);
1158 ConstantInt *C1; Value *X;
1159 // (X & C1) | C2 --> (X | C2) & (C1|C2)
1160 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1161 std::string Op0Name = Op0->getName(); Op0->setName("");
1162 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
1163 InsertNewInstBefore(Or, I);
1164 return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
1167 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
1168 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
1169 std::string Op0Name = Op0->getName(); Op0->setName("");
1170 Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
1171 InsertNewInstBefore(Or, I);
1172 return BinaryOperator::createXor(Or,
1173 ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
1176 // Try to fold constant and into select arguments.
1177 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1178 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1182 // (A & C1)|(A & C2) == A & (C1|C2)
1183 Value *A, *B; ConstantInt *C1, *C2;
1184 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
1185 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) && A == B)
1186 return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2));
1188 if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
1189 if (A == Op1) // ~A | A == -1
1190 return ReplaceInstUsesWith(I,
1191 ConstantIntegral::getAllOnesValue(I.getType()));
1196 if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
1198 return ReplaceInstUsesWith(I,
1199 ConstantIntegral::getAllOnesValue(I.getType()));
1201 // (~A | ~B) == (~(A & B)) - De Morgan's Law
1202 if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
1203 Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
1204 I.getName()+".demorgan"), I);
1205 return BinaryOperator::createNot(And);
1209 // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
1210 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
1211 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1214 return Changed ? &I : 0;
1217 // XorSelf - Implements: X ^ X --> 0
1220 XorSelf(Value *rhs) : RHS(rhs) {}
1221 bool shouldApply(Value *LHS) const { return LHS == RHS; }
1222 Instruction *apply(BinaryOperator &Xor) const {
1228 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
1229 bool Changed = SimplifyCommutative(I);
1230 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1232 // xor X, X = 0, even if X is nested in a sequence of Xor's.
1233 if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
1234 assert(Result == &I && "AssociativeOpt didn't work?");
1235 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
1238 if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
1240 if (RHS->isNullValue())
1241 return ReplaceInstUsesWith(I, Op0);
1243 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
1244 // xor (setcc A, B), true = not (setcc A, B) = setncc A, B
1245 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
1246 if (RHS == ConstantBool::True && SCI->hasOneUse())
1247 return new SetCondInst(SCI->getInverseCondition(),
1248 SCI->getOperand(0), SCI->getOperand(1));
1250 // ~(c-X) == X-c-1 == X+(-c-1)
1251 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
1252 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
1253 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
1254 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
1255 ConstantInt::get(I.getType(), 1));
1256 return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
1259 // ~(~X & Y) --> (X | ~Y)
1260 if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
1261 if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
1262 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
1264 BinaryOperator::createNot(Op0I->getOperand(1),
1265 Op0I->getOperand(1)->getName()+".not");
1266 InsertNewInstBefore(NotY, I);
1267 return BinaryOperator::createOr(Op0NotVal, NotY);
1271 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1272 switch (Op0I->getOpcode()) {
1273 case Instruction::Add:
1274 // ~(X-c) --> (-c-1)-X
1275 if (RHS->isAllOnesValue()) {
1276 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
1277 return BinaryOperator::createSub(
1278 ConstantExpr::getSub(NegOp0CI,
1279 ConstantInt::get(I.getType(), 1)),
1280 Op0I->getOperand(0));
1283 case Instruction::And:
1284 // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
1285 if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue())
1286 return BinaryOperator::createOr(Op0, RHS);
1288 case Instruction::Or:
1289 // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
1290 if (ConstantExpr::getAnd(RHS, Op0CI) == RHS)
1291 return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS));
1297 // Try to fold constant and into select arguments.
1298 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1299 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1303 if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
1305 return ReplaceInstUsesWith(I,
1306 ConstantIntegral::getAllOnesValue(I.getType()));
1308 if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
1310 return ReplaceInstUsesWith(I,
1311 ConstantIntegral::getAllOnesValue(I.getType()));
1313 if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
1314 if (Op1I->getOpcode() == Instruction::Or) {
1315 if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
1316 cast<BinaryOperator>(Op1I)->swapOperands();
1318 std::swap(Op0, Op1);
1319 } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
1321 std::swap(Op0, Op1);
1323 } else if (Op1I->getOpcode() == Instruction::Xor) {
1324 if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
1325 return ReplaceInstUsesWith(I, Op1I->getOperand(1));
1326 else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
1327 return ReplaceInstUsesWith(I, Op1I->getOperand(0));
1330 if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
1331 if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
1332 if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
1333 cast<BinaryOperator>(Op0I)->swapOperands();
1334 if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
1335 Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
1336 Op1->getName()+".not"), I);
1337 return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
1339 } else if (Op0I->getOpcode() == Instruction::Xor) {
1340 if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
1341 return ReplaceInstUsesWith(I, Op0I->getOperand(1));
1342 else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
1343 return ReplaceInstUsesWith(I, Op0I->getOperand(0));
1346 // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
1347 Value *A, *B; ConstantInt *C1, *C2;
1348 if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
1349 match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) &&
1350 ConstantExpr::getAnd(C1, C2)->isNullValue())
1351 return BinaryOperator::createOr(Op0, Op1);
1353 // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
1354 if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
1355 if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
1358 return Changed ? &I : 0;
1361 // AddOne, SubOne - Add or subtract a constant one from an integer constant...
1362 static Constant *AddOne(ConstantInt *C) {
1363 return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1));
1365 static Constant *SubOne(ConstantInt *C) {
1366 return ConstantExpr::getSub(C, ConstantInt::get(C->getType(), 1));
1369 // isTrueWhenEqual - Return true if the specified setcondinst instruction is
1370 // true when both operands are equal...
1372 static bool isTrueWhenEqual(Instruction &I) {
1373 return I.getOpcode() == Instruction::SetEQ ||
1374 I.getOpcode() == Instruction::SetGE ||
1375 I.getOpcode() == Instruction::SetLE;
1378 Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
1379 bool Changed = SimplifyCommutative(I);
1380 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1381 const Type *Ty = Op0->getType();
1385 return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
1387 // setcc <global/alloca*>, 0 - Global/Stack value addresses are never null!
1388 if (isa<ConstantPointerNull>(Op1) &&
1389 (isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0)))
1390 return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
1393 // setcc's with boolean values can always be turned into bitwise operations
1394 if (Ty == Type::BoolTy) {
1395 switch (I.getOpcode()) {
1396 default: assert(0 && "Invalid setcc instruction!");
1397 case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
1398 Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
1399 InsertNewInstBefore(Xor, I);
1400 return BinaryOperator::createNot(Xor);
1402 case Instruction::SetNE:
1403 return BinaryOperator::createXor(Op0, Op1);
1405 case Instruction::SetGT:
1406 std::swap(Op0, Op1); // Change setgt -> setlt
1408 case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
1409 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
1410 InsertNewInstBefore(Not, I);
1411 return BinaryOperator::createAnd(Not, Op1);
1413 case Instruction::SetGE:
1414 std::swap(Op0, Op1); // Change setge -> setle
1416 case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
1417 Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
1418 InsertNewInstBefore(Not, I);
1419 return BinaryOperator::createOr(Not, Op1);
1424 // See if we are doing a comparison between a constant and an instruction that
1425 // can be folded into the comparison.
1426 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
1427 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
1428 if (LHSI->hasOneUse())
1429 switch (LHSI->getOpcode()) {
1430 case Instruction::And:
1431 if (isa<ConstantInt>(LHSI->getOperand(1)) &&
1432 LHSI->getOperand(0)->hasOneUse()) {
1433 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
1434 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
1435 // happens a LOT in code produced by the C front-end, for bitfield
1437 ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
1438 ConstantUInt *ShAmt;
1439 ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
1440 ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
1441 const Type *Ty = LHSI->getType();
1443 // We can fold this as long as we can't shift unknown bits
1444 // into the mask. This can only happen with signed shift
1445 // rights, as they sign-extend.
1447 bool CanFold = Shift->getOpcode() != Instruction::Shr ||
1448 Shift->getType()->isUnsigned();
1450 // To test for the bad case of the signed shr, see if any
1451 // of the bits shifted in could be tested after the mask.
1452 Constant *OShAmt = ConstantUInt::get(Type::UByteTy,
1453 Ty->getPrimitiveSize()*8-ShAmt->getValue());
1455 ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
1456 if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
1461 unsigned ShiftOp = Shift->getOpcode() == Instruction::Shl
1462 ? Instruction::Shr : Instruction::Shl;
1463 Constant *NewCst = ConstantExpr::get(ShiftOp, CI, ShAmt);
1465 // Check to see if we are shifting out any of the bits being
1467 if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
1468 // If we shifted bits out, the fold is not going to work out.
1469 // As a special case, check to see if this means that the
1470 // result is always true or false now.
1471 if (I.getOpcode() == Instruction::SetEQ)
1472 return ReplaceInstUsesWith(I, ConstantBool::False);
1473 if (I.getOpcode() == Instruction::SetNE)
1474 return ReplaceInstUsesWith(I, ConstantBool::True);
1476 I.setOperand(1, NewCst);
1477 LHSI->setOperand(1, ConstantExpr::get(ShiftOp, AndCST,ShAmt));
1478 LHSI->setOperand(0, Shift->getOperand(0));
1479 WorkList.push_back(Shift); // Shift is dead.
1480 AddUsesToWorkList(I);
1487 case Instruction::Div:
1488 if (0 && isa<ConstantInt>(LHSI->getOperand(1))) {
1489 std::cerr << "COULD FOLD: " << *LHSI;
1490 std::cerr << "COULD FOLD: " << I << "\n";
1493 case Instruction::Select:
1494 // If either operand of the select is a constant, we can fold the
1495 // comparison into the select arms, which will cause one to be
1496 // constant folded and the select turned into a bitwise or.
1497 Value *Op1 = 0, *Op2 = 0;
1498 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
1499 // Fold the known value into the constant operand.
1500 Op1 = ConstantExpr::get(I.getOpcode(), C, CI);
1501 // Insert a new SetCC of the other select operand.
1502 Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
1503 LHSI->getOperand(2), CI,
1505 } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
1506 // Fold the known value into the constant operand.
1507 Op2 = ConstantExpr::get(I.getOpcode(), C, CI);
1508 // Insert a new SetCC of the other select operand.
1509 Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
1510 LHSI->getOperand(1), CI,
1515 return new SelectInst(LHSI->getOperand(0), Op1, Op2);
1519 // Simplify seteq and setne instructions...
1520 if (I.getOpcode() == Instruction::SetEQ ||
1521 I.getOpcode() == Instruction::SetNE) {
1522 bool isSetNE = I.getOpcode() == Instruction::SetNE;
1524 // If the first operand is (and|or|xor) with a constant, and the second
1525 // operand is a constant, simplify a bit.
1526 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
1527 switch (BO->getOpcode()) {
1528 case Instruction::Rem:
1529 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
1530 if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
1532 cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1)
1534 Log2(cast<ConstantSInt>(BO->getOperand(1))->getValue())) {
1535 const Type *UTy = BO->getType()->getUnsignedVersion();
1536 Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
1538 Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
1539 Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
1540 RHSCst, BO->getName()), I);
1541 return BinaryOperator::create(I.getOpcode(), NewRem,
1542 Constant::getNullValue(UTy));
1546 case Instruction::Add:
1547 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
1548 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
1549 if (BO->hasOneUse())
1550 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
1551 ConstantExpr::getSub(CI, BOp1C));
1552 } else if (CI->isNullValue()) {
1553 // Replace ((add A, B) != 0) with (A != -B) if A or B is
1554 // efficiently invertible, or if the add has just this one use.
1555 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
1557 if (Value *NegVal = dyn_castNegVal(BOp1))
1558 return new SetCondInst(I.getOpcode(), BOp0, NegVal);
1559 else if (Value *NegVal = dyn_castNegVal(BOp0))
1560 return new SetCondInst(I.getOpcode(), NegVal, BOp1);
1561 else if (BO->hasOneUse()) {
1562 Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
1564 InsertNewInstBefore(Neg, I);
1565 return new SetCondInst(I.getOpcode(), BOp0, Neg);
1569 case Instruction::Xor:
1570 // For the xor case, we can xor two constants together, eliminating
1571 // the explicit xor.
1572 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
1573 return BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
1574 ConstantExpr::getXor(CI, BOC));
1577 case Instruction::Sub:
1578 // Replace (([sub|xor] A, B) != 0) with (A != B)
1579 if (CI->isNullValue())
1580 return new SetCondInst(I.getOpcode(), BO->getOperand(0),
1584 case Instruction::Or:
1585 // If bits are being or'd in that are not present in the constant we
1586 // are comparing against, then the comparison could never succeed!
1587 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
1588 Constant *NotCI = ConstantExpr::getNot(CI);
1589 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
1590 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
1594 case Instruction::And:
1595 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
1596 // If bits are being compared against that are and'd out, then the
1597 // comparison can never succeed!
1598 if (!ConstantExpr::getAnd(CI,
1599 ConstantExpr::getNot(BOC))->isNullValue())
1600 return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
1602 // If we have ((X & C) == C), turn it into ((X & C) != 0).
1603 if (CI == BOC && isOneBitSet(CI))
1604 return new SetCondInst(isSetNE ? Instruction::SetEQ :
1605 Instruction::SetNE, Op0,
1606 Constant::getNullValue(CI->getType()));
1608 // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
1609 // to be a signed value as appropriate.
1610 if (isSignBit(BOC)) {
1611 Value *X = BO->getOperand(0);
1612 // If 'X' is not signed, insert a cast now...
1613 if (!BOC->getType()->isSigned()) {
1614 const Type *DestTy = BOC->getType()->getSignedVersion();
1615 CastInst *NewCI = new CastInst(X,DestTy,X->getName()+".signed");
1616 InsertNewInstBefore(NewCI, I);
1619 return new SetCondInst(isSetNE ? Instruction::SetLT :
1620 Instruction::SetGE, X,
1621 Constant::getNullValue(X->getType()));
1627 } else { // Not a SetEQ/SetNE
1628 // If the LHS is a cast from an integral value of the same size,
1629 if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
1630 Value *CastOp = Cast->getOperand(0);
1631 const Type *SrcTy = CastOp->getType();
1632 unsigned SrcTySize = SrcTy->getPrimitiveSize();
1633 if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
1634 SrcTySize == Cast->getType()->getPrimitiveSize()) {
1635 assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
1636 "Source and destination signednesses should differ!");
1637 if (Cast->getType()->isSigned()) {
1638 // If this is a signed comparison, check for comparisons in the
1639 // vicinity of zero.
1640 if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
1642 return BinaryOperator::createSetGT(CastOp,
1643 ConstantUInt::get(SrcTy, (1ULL << (SrcTySize*8-1))-1));
1644 else if (I.getOpcode() == Instruction::SetGT &&
1645 cast<ConstantSInt>(CI)->getValue() == -1)
1646 // X > -1 => x < 128
1647 return BinaryOperator::createSetLT(CastOp,
1648 ConstantUInt::get(SrcTy, 1ULL << (SrcTySize*8-1)));
1650 ConstantUInt *CUI = cast<ConstantUInt>(CI);
1651 if (I.getOpcode() == Instruction::SetLT &&
1652 CUI->getValue() == 1ULL << (SrcTySize*8-1))
1653 // X < 128 => X > -1
1654 return BinaryOperator::createSetGT(CastOp,
1655 ConstantSInt::get(SrcTy, -1));
1656 else if (I.getOpcode() == Instruction::SetGT &&
1657 CUI->getValue() == (1ULL << (SrcTySize*8-1))-1)
1659 return BinaryOperator::createSetLT(CastOp,
1660 Constant::getNullValue(SrcTy));
1666 // Check to see if we are comparing against the minimum or maximum value...
1667 if (CI->isMinValue()) {
1668 if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
1669 return ReplaceInstUsesWith(I, ConstantBool::False);
1670 if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
1671 return ReplaceInstUsesWith(I, ConstantBool::True);
1672 if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
1673 return BinaryOperator::createSetEQ(Op0, Op1);
1674 if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
1675 return BinaryOperator::createSetNE(Op0, Op1);
1677 } else if (CI->isMaxValue()) {
1678 if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
1679 return ReplaceInstUsesWith(I, ConstantBool::False);
1680 if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
1681 return ReplaceInstUsesWith(I, ConstantBool::True);
1682 if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
1683 return BinaryOperator::createSetEQ(Op0, Op1);
1684 if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
1685 return BinaryOperator::createSetNE(Op0, Op1);
1687 // Comparing against a value really close to min or max?
1688 } else if (isMinValuePlusOne(CI)) {
1689 if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
1690 return BinaryOperator::createSetEQ(Op0, SubOne(CI));
1691 if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
1692 return BinaryOperator::createSetNE(Op0, SubOne(CI));
1694 } else if (isMaxValueMinusOne(CI)) {
1695 if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
1696 return BinaryOperator::createSetEQ(Op0, AddOne(CI));
1697 if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
1698 return BinaryOperator::createSetNE(Op0, AddOne(CI));
1701 // If we still have a setle or setge instruction, turn it into the
1702 // appropriate setlt or setgt instruction. Since the border cases have
1703 // already been handled above, this requires little checking.
1705 if (I.getOpcode() == Instruction::SetLE)
1706 return BinaryOperator::createSetLT(Op0, AddOne(CI));
1707 if (I.getOpcode() == Instruction::SetGE)
1708 return BinaryOperator::createSetGT(Op0, SubOne(CI));
1711 // Test to see if the operands of the setcc are casted versions of other
1712 // values. If the cast can be stripped off both arguments, we do so now.
1713 if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
1714 Value *CastOp0 = CI->getOperand(0);
1715 if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
1716 (isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
1717 (I.getOpcode() == Instruction::SetEQ ||
1718 I.getOpcode() == Instruction::SetNE)) {
1719 // We keep moving the cast from the left operand over to the right
1720 // operand, where it can often be eliminated completely.
1723 // If operand #1 is a cast instruction, see if we can eliminate it as
1725 if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
1726 if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
1728 Op1 = CI2->getOperand(0);
1730 // If Op1 is a constant, we can fold the cast into the constant.
1731 if (Op1->getType() != Op0->getType())
1732 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
1733 Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
1735 // Otherwise, cast the RHS right before the setcc
1736 Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
1737 InsertNewInstBefore(cast<Instruction>(Op1), I);
1739 return BinaryOperator::create(I.getOpcode(), Op0, Op1);
1742 // Handle the special case of: setcc (cast bool to X), <cst>
1743 // This comes up when you have code like
1746 // For generality, we handle any zero-extension of any operand comparison
1748 if (ConstantInt *ConstantRHS = dyn_cast<ConstantInt>(Op1)) {
1749 const Type *SrcTy = CastOp0->getType();
1750 const Type *DestTy = Op0->getType();
1751 if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
1752 (SrcTy->isUnsigned() || SrcTy == Type::BoolTy)) {
1753 // Ok, we have an expansion of operand 0 into a new type. Get the
1754 // constant value, masink off bits which are not set in the RHS. These
1755 // could be set if the destination value is signed.
1756 uint64_t ConstVal = ConstantRHS->getRawValue();
1757 ConstVal &= (1ULL << DestTy->getPrimitiveSize()*8)-1;
1759 // If the constant we are comparing it with has high bits set, which
1760 // don't exist in the original value, the values could never be equal,
1761 // because the source would be zero extended.
1763 SrcTy == Type::BoolTy ? 1 : SrcTy->getPrimitiveSize()*8;
1764 bool HasSignBit = ConstVal & (1ULL << (DestTy->getPrimitiveSize()*8-1));
1765 if (ConstVal & ~((1ULL << SrcBits)-1)) {
1766 switch (I.getOpcode()) {
1767 default: assert(0 && "Unknown comparison type!");
1768 case Instruction::SetEQ:
1769 return ReplaceInstUsesWith(I, ConstantBool::False);
1770 case Instruction::SetNE:
1771 return ReplaceInstUsesWith(I, ConstantBool::True);
1772 case Instruction::SetLT:
1773 case Instruction::SetLE:
1774 if (DestTy->isSigned() && HasSignBit)
1775 return ReplaceInstUsesWith(I, ConstantBool::False);
1776 return ReplaceInstUsesWith(I, ConstantBool::True);
1777 case Instruction::SetGT:
1778 case Instruction::SetGE:
1779 if (DestTy->isSigned() && HasSignBit)
1780 return ReplaceInstUsesWith(I, ConstantBool::True);
1781 return ReplaceInstUsesWith(I, ConstantBool::False);
1785 // Otherwise, we can replace the setcc with a setcc of the smaller
1787 Op1 = ConstantExpr::getCast(cast<Constant>(Op1), SrcTy);
1788 return BinaryOperator::create(I.getOpcode(), CastOp0, Op1);
1792 return Changed ? &I : 0;
1797 Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
1798 assert(I.getOperand(1)->getType() == Type::UByteTy);
1799 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1800 bool isLeftShift = I.getOpcode() == Instruction::Shl;
1802 // shl X, 0 == X and shr X, 0 == X
1803 // shl 0, X == 0 and shr 0, X == 0
1804 if (Op1 == Constant::getNullValue(Type::UByteTy) ||
1805 Op0 == Constant::getNullValue(Op0->getType()))
1806 return ReplaceInstUsesWith(I, Op0);
1808 // shr int -1, X = -1 (for any arithmetic shift rights of ~0)
1810 if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
1811 if (CSI->isAllOnesValue())
1812 return ReplaceInstUsesWith(I, CSI);
1814 // Try to fold constant and into select arguments.
1815 if (isa<Constant>(Op0))
1816 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
1817 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1820 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
1821 // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
1822 // of a signed value.
1824 unsigned TypeBits = Op0->getType()->getPrimitiveSize()*8;
1825 if (CUI->getValue() >= TypeBits) {
1826 if (!Op0->getType()->isSigned() || isLeftShift)
1827 return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
1829 I.setOperand(1, ConstantUInt::get(Type::UByteTy, TypeBits-1));
1834 // ((X*C1) << C2) == (X * (C1 << C2))
1835 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
1836 if (BO->getOpcode() == Instruction::Mul && isLeftShift)
1837 if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
1838 return BinaryOperator::createMul(BO->getOperand(0),
1839 ConstantExpr::getShl(BOOp, CUI));
1841 // Try to fold constant and into select arguments.
1842 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1843 if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
1846 // If the operand is an bitwise operator with a constant RHS, and the
1847 // shift is the only use, we can pull it out of the shift.
1848 if (Op0->hasOneUse())
1849 if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0))
1850 if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
1851 bool isValid = true; // Valid only for And, Or, Xor
1852 bool highBitSet = false; // Transform if high bit of constant set?
1854 switch (Op0BO->getOpcode()) {
1855 default: isValid = false; break; // Do not perform transform!
1856 case Instruction::Or:
1857 case Instruction::Xor:
1860 case Instruction::And:
1865 // If this is a signed shift right, and the high bit is modified
1866 // by the logical operation, do not perform the transformation.
1867 // The highBitSet boolean indicates the value of the high bit of
1868 // the constant which would cause it to be modified for this
1871 if (isValid && !isLeftShift && !I.getType()->isUnsigned()) {
1872 uint64_t Val = Op0C->getRawValue();
1873 isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
1877 Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI);
1879 Instruction *NewShift =
1880 new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI,
1883 InsertNewInstBefore(NewShift, I);
1885 return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
1890 // If this is a shift of a shift, see if we can fold the two together...
1891 if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
1892 if (ConstantUInt *ShiftAmt1C =
1893 dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) {
1894 unsigned ShiftAmt1 = ShiftAmt1C->getValue();
1895 unsigned ShiftAmt2 = CUI->getValue();
1897 // Check for (A << c1) << c2 and (A >> c1) >> c2
1898 if (I.getOpcode() == Op0SI->getOpcode()) {
1899 unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
1900 if (Op0->getType()->getPrimitiveSize()*8 < Amt)
1901 Amt = Op0->getType()->getPrimitiveSize()*8;
1902 return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
1903 ConstantUInt::get(Type::UByteTy, Amt));
1906 // Check for (A << c1) >> c2 or visaversa. If we are dealing with
1907 // signed types, we can only support the (A >> c1) << c2 configuration,
1908 // because it can not turn an arbitrary bit of A into a sign bit.
1909 if (I.getType()->isUnsigned() || isLeftShift) {
1910 // Calculate bitmask for what gets shifted off the edge...
1911 Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
1913 C = ConstantExpr::getShl(C, ShiftAmt1C);
1915 C = ConstantExpr::getShr(C, ShiftAmt1C);
1918 BinaryOperator::createAnd(Op0SI->getOperand(0), C,
1919 Op0SI->getOperand(0)->getName()+".mask");
1920 InsertNewInstBefore(Mask, I);
1922 // Figure out what flavor of shift we should use...
1923 if (ShiftAmt1 == ShiftAmt2)
1924 return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
1925 else if (ShiftAmt1 < ShiftAmt2) {
1926 return new ShiftInst(I.getOpcode(), Mask,
1927 ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
1929 return new ShiftInst(Op0SI->getOpcode(), Mask,
1930 ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
1946 /// getCastType - In the future, we will split the cast instruction into these
1947 /// various types. Until then, we have to do the analysis here.
1948 static CastType getCastType(const Type *Src, const Type *Dest) {
1949 assert(Src->isIntegral() && Dest->isIntegral() &&
1950 "Only works on integral types!");
1951 unsigned SrcSize = Src->getPrimitiveSize()*8;
1952 if (Src == Type::BoolTy) SrcSize = 1;
1953 unsigned DestSize = Dest->getPrimitiveSize()*8;
1954 if (Dest == Type::BoolTy) DestSize = 1;
1956 if (SrcSize == DestSize) return Noop;
1957 if (SrcSize > DestSize) return Truncate;
1958 if (Src->isSigned()) return Signext;
1963 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
1966 static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
1967 const Type *DstTy, TargetData *TD) {
1969 // It is legal to eliminate the instruction if casting A->B->A if the sizes
1970 // are identical and the bits don't get reinterpreted (for example
1971 // int->float->int would not be allowed).
1972 if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
1975 // If we are casting between pointer and integer types, treat pointers as
1976 // integers of the appropriate size for the code below.
1977 if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
1978 if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
1979 if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
1981 // Allow free casting and conversion of sizes as long as the sign doesn't
1983 if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
1984 CastType FirstCast = getCastType(SrcTy, MidTy);
1985 CastType SecondCast = getCastType(MidTy, DstTy);
1987 // Capture the effect of these two casts. If the result is a legal cast,
1988 // the CastType is stored here, otherwise a special code is used.
1989 static const unsigned CastResult[] = {
1990 // First cast is noop
1992 // First cast is a truncate
1993 1, 1, 4, 4, // trunc->extend is not safe to eliminate
1994 // First cast is a sign ext
1995 2, 5, 2, 4, // signext->zeroext never ok
1996 // First cast is a zero ext
2000 unsigned Result = CastResult[FirstCast*4+SecondCast];
2002 default: assert(0 && "Illegal table value!");
2007 // FIXME: in the future, when LLVM has explicit sign/zeroextends and
2008 // truncates, we could eliminate more casts.
2009 return (unsigned)getCastType(SrcTy, DstTy) == Result;
2011 return false; // Not possible to eliminate this here.
2013 // Sign or zero extend followed by truncate is always ok if the result
2014 // is a truncate or noop.
2015 CastType ResultCast = getCastType(SrcTy, DstTy);
2016 if (ResultCast == Noop || ResultCast == Truncate)
2018 // Otherwise we are still growing the value, we are only safe if the
2019 // result will match the sign/zeroextendness of the result.
2020 return ResultCast == FirstCast;
2026 static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
2027 if (V->getType() == Ty || isa<Constant>(V)) return false;
2028 if (const CastInst *CI = dyn_cast<CastInst>(V))
2029 if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
2035 /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
2036 /// InsertBefore instruction. This is specialized a bit to avoid inserting
2037 /// casts that are known to not do anything...
2039 Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
2040 Instruction *InsertBefore) {
2041 if (V->getType() == DestTy) return V;
2042 if (Constant *C = dyn_cast<Constant>(V))
2043 return ConstantExpr::getCast(C, DestTy);
2045 CastInst *CI = new CastInst(V, DestTy, V->getName());
2046 InsertNewInstBefore(CI, *InsertBefore);
2050 // CastInst simplification
2052 Instruction *InstCombiner::visitCastInst(CastInst &CI) {
2053 Value *Src = CI.getOperand(0);
2055 // If the user is casting a value to the same type, eliminate this cast
2057 if (CI.getType() == Src->getType())
2058 return ReplaceInstUsesWith(CI, Src);
2060 // If casting the result of another cast instruction, try to eliminate this
2063 if (CastInst *CSrc = dyn_cast<CastInst>(Src)) {
2064 if (isEliminableCastOfCast(CSrc->getOperand(0)->getType(),
2065 CSrc->getType(), CI.getType(), TD)) {
2066 // This instruction now refers directly to the cast's src operand. This
2067 // has a good chance of making CSrc dead.
2068 CI.setOperand(0, CSrc->getOperand(0));
2072 // If this is an A->B->A cast, and we are dealing with integral types, try
2073 // to convert this into a logical 'and' instruction.
2075 if (CSrc->getOperand(0)->getType() == CI.getType() &&
2076 CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
2077 CI.getType()->isUnsigned() && CSrc->getType()->isUnsigned() &&
2078 CSrc->getType()->getPrimitiveSize() < CI.getType()->getPrimitiveSize()){
2079 assert(CSrc->getType() != Type::ULongTy &&
2080 "Cannot have type bigger than ulong!");
2081 uint64_t AndValue = (1ULL << CSrc->getType()->getPrimitiveSize()*8)-1;
2082 Constant *AndOp = ConstantUInt::get(CI.getType(), AndValue);
2083 return BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
2087 // If this is a cast to bool, turn it into the appropriate setne instruction.
2088 if (CI.getType() == Type::BoolTy)
2089 return BinaryOperator::createSetNE(CI.getOperand(0),
2090 Constant::getNullValue(CI.getOperand(0)->getType()));
2092 // If casting the result of a getelementptr instruction with no offset, turn
2093 // this into a cast of the original pointer!
2095 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
2096 bool AllZeroOperands = true;
2097 for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
2098 if (!isa<Constant>(GEP->getOperand(i)) ||
2099 !cast<Constant>(GEP->getOperand(i))->isNullValue()) {
2100 AllZeroOperands = false;
2103 if (AllZeroOperands) {
2104 CI.setOperand(0, GEP->getOperand(0));
2109 // If we are casting a malloc or alloca to a pointer to a type of the same
2110 // size, rewrite the allocation instruction to allocate the "right" type.
2112 if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
2113 if (AI->hasOneUse() && !AI->isArrayAllocation())
2114 if (const PointerType *PTy = dyn_cast<PointerType>(CI.getType())) {
2115 // Get the type really allocated and the type casted to...
2116 const Type *AllocElTy = AI->getAllocatedType();
2117 const Type *CastElTy = PTy->getElementType();
2118 if (AllocElTy->isSized() && CastElTy->isSized()) {
2119 unsigned AllocElTySize = TD->getTypeSize(AllocElTy);
2120 unsigned CastElTySize = TD->getTypeSize(CastElTy);
2122 // If the allocation is for an even multiple of the cast type size
2123 if (CastElTySize && (AllocElTySize % CastElTySize == 0)) {
2124 Value *Amt = ConstantUInt::get(Type::UIntTy,
2125 AllocElTySize/CastElTySize);
2126 std::string Name = AI->getName(); AI->setName("");
2127 AllocationInst *New;
2128 if (isa<MallocInst>(AI))
2129 New = new MallocInst(CastElTy, Amt, Name);
2131 New = new AllocaInst(CastElTy, Amt, Name);
2132 InsertNewInstBefore(New, *AI);
2133 return ReplaceInstUsesWith(CI, New);
2138 // If the source value is an instruction with only this use, we can attempt to
2139 // propagate the cast into the instruction. Also, only handle integral types
2141 if (Instruction *SrcI = dyn_cast<Instruction>(Src))
2142 if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
2143 CI.getType()->isInteger()) { // Don't mess with casts to bool here
2144 const Type *DestTy = CI.getType();
2145 unsigned SrcBitSize = getTypeSizeInBits(Src->getType());
2146 unsigned DestBitSize = getTypeSizeInBits(DestTy);
2148 Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
2149 Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
2151 switch (SrcI->getOpcode()) {
2152 case Instruction::Add:
2153 case Instruction::Mul:
2154 case Instruction::And:
2155 case Instruction::Or:
2156 case Instruction::Xor:
2157 // If we are discarding information, or just changing the sign, rewrite.
2158 if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
2159 // Don't insert two casts if they cannot be eliminated. We allow two
2160 // casts to be inserted if the sizes are the same. This could only be
2161 // converting signedness, which is a noop.
2162 if (DestBitSize == SrcBitSize || !ValueRequiresCast(Op1, DestTy,TD) ||
2163 !ValueRequiresCast(Op0, DestTy, TD)) {
2164 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
2165 Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
2166 return BinaryOperator::create(cast<BinaryOperator>(SrcI)
2167 ->getOpcode(), Op0c, Op1c);
2171 case Instruction::Shl:
2172 // Allow changing the sign of the source operand. Do not allow changing
2173 // the size of the shift, UNLESS the shift amount is a constant. We
2174 // mush not change variable sized shifts to a smaller size, because it
2175 // is undefined to shift more bits out than exist in the value.
2176 if (DestBitSize == SrcBitSize ||
2177 (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
2178 Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
2179 return new ShiftInst(Instruction::Shl, Op0c, Op1);
2188 /// GetSelectFoldableOperands - We want to turn code that looks like this:
2190 /// %D = select %cond, %C, %A
2192 /// %C = select %cond, %B, 0
2195 /// Assuming that the specified instruction is an operand to the select, return
2196 /// a bitmask indicating which operands of this instruction are foldable if they
2197 /// equal the other incoming value of the select.
2199 static unsigned GetSelectFoldableOperands(Instruction *I) {
2200 switch (I->getOpcode()) {
2201 case Instruction::Add:
2202 case Instruction::Mul:
2203 case Instruction::And:
2204 case Instruction::Or:
2205 case Instruction::Xor:
2206 return 3; // Can fold through either operand.
2207 case Instruction::Sub: // Can only fold on the amount subtracted.
2208 case Instruction::Shl: // Can only fold on the shift amount.
2209 case Instruction::Shr:
2212 return 0; // Cannot fold
2216 /// GetSelectFoldableConstant - For the same transformation as the previous
2217 /// function, return the identity constant that goes into the select.
2218 static Constant *GetSelectFoldableConstant(Instruction *I) {
2219 switch (I->getOpcode()) {
2220 default: assert(0 && "This cannot happen!"); abort();
2221 case Instruction::Add:
2222 case Instruction::Sub:
2223 case Instruction::Or:
2224 case Instruction::Xor:
2225 return Constant::getNullValue(I->getType());
2226 case Instruction::Shl:
2227 case Instruction::Shr:
2228 return Constant::getNullValue(Type::UByteTy);
2229 case Instruction::And:
2230 return ConstantInt::getAllOnesValue(I->getType());
2231 case Instruction::Mul:
2232 return ConstantInt::get(I->getType(), 1);
2236 Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
2237 Value *CondVal = SI.getCondition();
2238 Value *TrueVal = SI.getTrueValue();
2239 Value *FalseVal = SI.getFalseValue();
2241 // select true, X, Y -> X
2242 // select false, X, Y -> Y
2243 if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
2244 if (C == ConstantBool::True)
2245 return ReplaceInstUsesWith(SI, TrueVal);
2247 assert(C == ConstantBool::False);
2248 return ReplaceInstUsesWith(SI, FalseVal);
2251 // select C, X, X -> X
2252 if (TrueVal == FalseVal)
2253 return ReplaceInstUsesWith(SI, TrueVal);
2255 if (SI.getType() == Type::BoolTy)
2256 if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
2257 if (C == ConstantBool::True) {
2258 // Change: A = select B, true, C --> A = or B, C
2259 return BinaryOperator::createOr(CondVal, FalseVal);
2261 // Change: A = select B, false, C --> A = and !B, C
2263 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
2264 "not."+CondVal->getName()), SI);
2265 return BinaryOperator::createAnd(NotCond, FalseVal);
2267 } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
2268 if (C == ConstantBool::False) {
2269 // Change: A = select B, C, false --> A = and B, C
2270 return BinaryOperator::createAnd(CondVal, TrueVal);
2272 // Change: A = select B, C, true --> A = or !B, C
2274 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
2275 "not."+CondVal->getName()), SI);
2276 return BinaryOperator::createOr(NotCond, TrueVal);
2280 // Selecting between two integer constants?
2281 if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
2282 if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
2283 // select C, 1, 0 -> cast C to int
2284 if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
2285 return new CastInst(CondVal, SI.getType());
2286 } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
2287 // select C, 0, 1 -> cast !C to int
2289 InsertNewInstBefore(BinaryOperator::createNot(CondVal,
2290 "not."+CondVal->getName()), SI);
2291 return new CastInst(NotCond, SI.getType());
2294 // If one of the constants is zero (we know they can't both be) and we
2295 // have a setcc instruction with zero, and we have an 'and' with the
2296 // non-constant value, eliminate this whole mess. This corresponds to
2297 // cases like this: ((X & 27) ? 27 : 0)
2298 if (TrueValC->isNullValue() || FalseValC->isNullValue())
2299 if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
2300 if ((IC->getOpcode() == Instruction::SetEQ ||
2301 IC->getOpcode() == Instruction::SetNE) &&
2302 isa<ConstantInt>(IC->getOperand(1)) &&
2303 cast<Constant>(IC->getOperand(1))->isNullValue())
2304 if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
2305 if (ICA->getOpcode() == Instruction::And &&
2306 isa<ConstantInt>(ICA->getOperand(1)) &&
2307 (ICA->getOperand(1) == TrueValC ||
2308 ICA->getOperand(1) == FalseValC) &&
2309 isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
2310 // Okay, now we know that everything is set up, we just don't
2311 // know whether we have a setne or seteq and whether the true or
2312 // false val is the zero.
2313 bool ShouldNotVal = !TrueValC->isNullValue();
2314 ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
2317 V = InsertNewInstBefore(BinaryOperator::create(
2318 Instruction::Xor, V, ICA->getOperand(1)), SI);
2319 return ReplaceInstUsesWith(SI, V);
2323 // See if we are selecting two values based on a comparison of the two values.
2324 if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
2325 if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
2326 // Transform (X == Y) ? X : Y -> Y
2327 if (SCI->getOpcode() == Instruction::SetEQ)
2328 return ReplaceInstUsesWith(SI, FalseVal);
2329 // Transform (X != Y) ? X : Y -> X
2330 if (SCI->getOpcode() == Instruction::SetNE)
2331 return ReplaceInstUsesWith(SI, TrueVal);
2332 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
2334 } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
2335 // Transform (X == Y) ? Y : X -> X
2336 if (SCI->getOpcode() == Instruction::SetEQ)
2337 return ReplaceInstUsesWith(SI, FalseVal);
2338 // Transform (X != Y) ? Y : X -> Y
2339 if (SCI->getOpcode() == Instruction::SetNE)
2340 return ReplaceInstUsesWith(SI, TrueVal);
2341 // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
2345 // See if we can fold the select into one of our operands.
2346 if (SI.getType()->isInteger()) {
2347 // See the comment above GetSelectFoldableOperands for a description of the
2348 // transformation we are doing here.
2349 if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
2350 if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
2351 !isa<Constant>(FalseVal))
2352 if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
2353 unsigned OpToFold = 0;
2354 if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
2356 } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
2361 Constant *C = GetSelectFoldableConstant(TVI);
2362 std::string Name = TVI->getName(); TVI->setName("");
2363 Instruction *NewSel =
2364 new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
2366 InsertNewInstBefore(NewSel, SI);
2367 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
2368 return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
2369 else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
2370 return new ShiftInst(SI->getOpcode(), FalseVal, NewSel);
2372 assert(0 && "Unknown instruction!!");
2377 if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
2378 if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
2379 !isa<Constant>(TrueVal))
2380 if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
2381 unsigned OpToFold = 0;
2382 if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
2384 } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
2389 Constant *C = GetSelectFoldableConstant(FVI);
2390 std::string Name = FVI->getName(); FVI->setName("");
2391 Instruction *NewSel =
2392 new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
2394 InsertNewInstBefore(NewSel, SI);
2395 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
2396 return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
2397 else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
2398 return new ShiftInst(SI->getOpcode(), TrueVal, NewSel);
2400 assert(0 && "Unknown instruction!!");
2409 // CallInst simplification
2411 Instruction *InstCombiner::visitCallInst(CallInst &CI) {
2412 // Intrinsics cannot occur in an invoke, so handle them here instead of in
2414 if (Function *F = CI.getCalledFunction())
2415 switch (F->getIntrinsicID()) {
2416 case Intrinsic::memmove:
2417 case Intrinsic::memcpy:
2418 case Intrinsic::memset:
2419 // memmove/cpy/set of zero bytes is a noop.
2420 if (Constant *NumBytes = dyn_cast<Constant>(CI.getOperand(3))) {
2421 if (NumBytes->isNullValue())
2422 return EraseInstFromFunction(CI);
2429 return visitCallSite(&CI);
2432 // InvokeInst simplification
2434 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
2435 return visitCallSite(&II);
2438 // visitCallSite - Improvements for call and invoke instructions.
2440 Instruction *InstCombiner::visitCallSite(CallSite CS) {
2441 bool Changed = false;
2443 // If the callee is a constexpr cast of a function, attempt to move the cast
2444 // to the arguments of the call/invoke.
2445 if (transformConstExprCastCall(CS)) return 0;
2447 Value *Callee = CS.getCalledValue();
2448 const PointerType *PTy = cast<PointerType>(Callee->getType());
2449 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
2450 if (FTy->isVarArg()) {
2451 // See if we can optimize any arguments passed through the varargs area of
2453 for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
2454 E = CS.arg_end(); I != E; ++I)
2455 if (CastInst *CI = dyn_cast<CastInst>(*I)) {
2456 // If this cast does not effect the value passed through the varargs
2457 // area, we can eliminate the use of the cast.
2458 Value *Op = CI->getOperand(0);
2459 if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
2466 return Changed ? CS.getInstruction() : 0;
2469 // transformConstExprCastCall - If the callee is a constexpr cast of a function,
2470 // attempt to move the cast to the arguments of the call/invoke.
2472 bool InstCombiner::transformConstExprCastCall(CallSite CS) {
2473 if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
2474 ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
2475 if (CE->getOpcode() != Instruction::Cast || !isa<Function>(CE->getOperand(0)))
2477 Function *Callee = cast<Function>(CE->getOperand(0));
2478 Instruction *Caller = CS.getInstruction();
2480 // Okay, this is a cast from a function to a different type. Unless doing so
2481 // would cause a type conversion of one of our arguments, change this call to
2482 // be a direct call with arguments casted to the appropriate types.
2484 const FunctionType *FT = Callee->getFunctionType();
2485 const Type *OldRetTy = Caller->getType();
2487 // Check to see if we are changing the return type...
2488 if (OldRetTy != FT->getReturnType()) {
2489 if (Callee->isExternal() &&
2490 !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
2491 !Caller->use_empty())
2492 return false; // Cannot transform this return value...
2494 // If the callsite is an invoke instruction, and the return value is used by
2495 // a PHI node in a successor, we cannot change the return type of the call
2496 // because there is no place to put the cast instruction (without breaking
2497 // the critical edge). Bail out in this case.
2498 if (!Caller->use_empty())
2499 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
2500 for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
2502 if (PHINode *PN = dyn_cast<PHINode>(*UI))
2503 if (PN->getParent() == II->getNormalDest() ||
2504 PN->getParent() == II->getUnwindDest())
2508 unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
2509 unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
2511 CallSite::arg_iterator AI = CS.arg_begin();
2512 for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
2513 const Type *ParamTy = FT->getParamType(i);
2514 bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
2515 if (Callee->isExternal() && !isConvertible) return false;
2518 if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
2519 Callee->isExternal())
2520 return false; // Do not delete arguments unless we have a function body...
2522 // Okay, we decided that this is a safe thing to do: go ahead and start
2523 // inserting cast instructions as necessary...
2524 std::vector<Value*> Args;
2525 Args.reserve(NumActualArgs);
2527 AI = CS.arg_begin();
2528 for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
2529 const Type *ParamTy = FT->getParamType(i);
2530 if ((*AI)->getType() == ParamTy) {
2531 Args.push_back(*AI);
2533 Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
2538 // If the function takes more arguments than the call was taking, add them
2540 for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
2541 Args.push_back(Constant::getNullValue(FT->getParamType(i)));
2543 // If we are removing arguments to the function, emit an obnoxious warning...
2544 if (FT->getNumParams() < NumActualArgs)
2545 if (!FT->isVarArg()) {
2546 std::cerr << "WARNING: While resolving call to function '"
2547 << Callee->getName() << "' arguments were dropped!\n";
2549 // Add all of the arguments in their promoted form to the arg list...
2550 for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
2551 const Type *PTy = getPromotedType((*AI)->getType());
2552 if (PTy != (*AI)->getType()) {
2553 // Must promote to pass through va_arg area!
2554 Instruction *Cast = new CastInst(*AI, PTy, "tmp");
2555 InsertNewInstBefore(Cast, *Caller);
2556 Args.push_back(Cast);
2558 Args.push_back(*AI);
2563 if (FT->getReturnType() == Type::VoidTy)
2564 Caller->setName(""); // Void type should not have a name...
2567 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
2568 NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
2569 Args, Caller->getName(), Caller);
2571 NC = new CallInst(Callee, Args, Caller->getName(), Caller);
2574 // Insert a cast of the return type as necessary...
2576 if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
2577 if (NV->getType() != Type::VoidTy) {
2578 NV = NC = new CastInst(NC, Caller->getType(), "tmp");
2580 // If this is an invoke instruction, we should insert it after the first
2581 // non-phi, instruction in the normal successor block.
2582 if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
2583 BasicBlock::iterator I = II->getNormalDest()->begin();
2584 while (isa<PHINode>(I)) ++I;
2585 InsertNewInstBefore(NC, *I);
2587 // Otherwise, it's a call, just insert cast right after the call instr
2588 InsertNewInstBefore(NC, *Caller);
2590 AddUsersToWorkList(*Caller);
2592 NV = Constant::getNullValue(Caller->getType());
2596 if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
2597 Caller->replaceAllUsesWith(NV);
2598 Caller->getParent()->getInstList().erase(Caller);
2599 removeFromWorkList(Caller);
2605 // PHINode simplification
2607 Instruction *InstCombiner::visitPHINode(PHINode &PN) {
2608 if (Value *V = hasConstantValue(&PN))
2609 return ReplaceInstUsesWith(PN, V);
2611 // If the only user of this instruction is a cast instruction, and all of the
2612 // incoming values are constants, change this PHI to merge together the casted
2615 if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
2616 if (CI->getType() != PN.getType()) { // noop casts will be folded
2617 bool AllConstant = true;
2618 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
2619 if (!isa<Constant>(PN.getIncomingValue(i))) {
2620 AllConstant = false;
2624 // Make a new PHI with all casted values.
2625 PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
2626 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2627 Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
2628 New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
2629 PN.getIncomingBlock(i));
2632 // Update the cast instruction.
2633 CI->setOperand(0, New);
2634 WorkList.push_back(CI); // revisit the cast instruction to fold.
2635 WorkList.push_back(New); // Make sure to revisit the new Phi
2636 return &PN; // PN is now dead!
2642 static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
2643 Instruction *InsertPoint,
2645 unsigned PS = IC->getTargetData().getPointerSize();
2646 const Type *VTy = V->getType();
2648 if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
2649 // We must insert a cast to ensure we sign-extend.
2650 V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
2651 V->getName()), *InsertPoint);
2652 return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
2657 Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
2658 Value *PtrOp = GEP.getOperand(0);
2659 // Is it 'getelementptr %P, long 0' or 'getelementptr %P'
2660 // If so, eliminate the noop.
2661 if (GEP.getNumOperands() == 1)
2662 return ReplaceInstUsesWith(GEP, PtrOp);
2664 bool HasZeroPointerIndex = false;
2665 if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
2666 HasZeroPointerIndex = C->isNullValue();
2668 if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
2669 return ReplaceInstUsesWith(GEP, PtrOp);
2671 // Eliminate unneeded casts for indices.
2672 bool MadeChange = false;
2673 gep_type_iterator GTI = gep_type_begin(GEP);
2674 for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
2675 if (isa<SequentialType>(*GTI)) {
2676 if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
2677 Value *Src = CI->getOperand(0);
2678 const Type *SrcTy = Src->getType();
2679 const Type *DestTy = CI->getType();
2680 if (Src->getType()->isInteger()) {
2681 if (SrcTy->getPrimitiveSize() == DestTy->getPrimitiveSize()) {
2682 // We can always eliminate a cast from ulong or long to the other.
2683 // We can always eliminate a cast from uint to int or the other on
2684 // 32-bit pointer platforms.
2685 if (DestTy->getPrimitiveSize() >= TD->getPointerSize()) {
2687 GEP.setOperand(i, Src);
2689 } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
2690 SrcTy->getPrimitiveSize() == 4) {
2691 // We can always eliminate a cast from int to [u]long. We can
2692 // eliminate a cast from uint to [u]long iff the target is a 32-bit
2694 if (SrcTy->isSigned() ||
2695 SrcTy->getPrimitiveSize() >= TD->getPointerSize()) {
2697 GEP.setOperand(i, Src);
2702 // If we are using a wider index than needed for this platform, shrink it
2703 // to what we need. If the incoming value needs a cast instruction,
2704 // insert it. This explicit cast can make subsequent optimizations more
2706 Value *Op = GEP.getOperand(i);
2707 if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
2708 if (Constant *C = dyn_cast<Constant>(Op)) {
2709 GEP.setOperand(i, ConstantExpr::getCast(C,
2710 TD->getIntPtrType()->getSignedVersion()));
2713 Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
2714 Op->getName()), GEP);
2715 GEP.setOperand(i, Op);
2719 // If this is a constant idx, make sure to canonicalize it to be a signed
2720 // operand, otherwise CSE and other optimizations are pessimized.
2721 if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
2722 GEP.setOperand(i, ConstantExpr::getCast(CUI,
2723 CUI->getType()->getSignedVersion()));
2727 if (MadeChange) return &GEP;
2729 // Combine Indices - If the source pointer to this getelementptr instruction
2730 // is a getelementptr instruction, combine the indices of the two
2731 // getelementptr instructions into a single instruction.
2733 std::vector<Value*> SrcGEPOperands;
2734 if (GetElementPtrInst *Src = dyn_cast<GetElementPtrInst>(PtrOp)) {
2735 SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
2736 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(PtrOp)) {
2737 if (CE->getOpcode() == Instruction::GetElementPtr)
2738 SrcGEPOperands.assign(CE->op_begin(), CE->op_end());
2741 if (!SrcGEPOperands.empty()) {
2742 // Note that if our source is a gep chain itself that we wait for that
2743 // chain to be resolved before we perform this transformation. This
2744 // avoids us creating a TON of code in some cases.
2746 if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
2747 cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
2748 return 0; // Wait until our source is folded to completion.
2750 std::vector<Value *> Indices;
2752 // Find out whether the last index in the source GEP is a sequential idx.
2753 bool EndsWithSequential = false;
2754 for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
2755 E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
2756 EndsWithSequential = !isa<StructType>(*I);
2758 // Can we combine the two pointer arithmetics offsets?
2759 if (EndsWithSequential) {
2760 // Replace: gep (gep %P, long B), long A, ...
2761 // With: T = long A+B; gep %P, T, ...
2763 Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
2764 if (SO1 == Constant::getNullValue(SO1->getType())) {
2766 } else if (GO1 == Constant::getNullValue(GO1->getType())) {
2769 // If they aren't the same type, convert both to an integer of the
2770 // target's pointer size.
2771 if (SO1->getType() != GO1->getType()) {
2772 if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
2773 SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
2774 } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
2775 GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
2777 unsigned PS = TD->getPointerSize();
2779 if (SO1->getType()->getPrimitiveSize() == PS) {
2780 // Convert GO1 to SO1's type.
2781 GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
2783 } else if (GO1->getType()->getPrimitiveSize() == PS) {
2784 // Convert SO1 to GO1's type.
2785 SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
2787 const Type *PT = TD->getIntPtrType();
2788 SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
2789 GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
2793 if (isa<Constant>(SO1) && isa<Constant>(GO1))
2794 Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
2796 Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
2797 InsertNewInstBefore(cast<Instruction>(Sum), GEP);
2801 // Recycle the GEP we already have if possible.
2802 if (SrcGEPOperands.size() == 2) {
2803 GEP.setOperand(0, SrcGEPOperands[0]);
2804 GEP.setOperand(1, Sum);
2807 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
2808 SrcGEPOperands.end()-1);
2809 Indices.push_back(Sum);
2810 Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
2812 } else if (isa<Constant>(*GEP.idx_begin()) &&
2813 cast<Constant>(*GEP.idx_begin())->isNullValue() &&
2814 SrcGEPOperands.size() != 1) {
2815 // Otherwise we can do the fold if the first index of the GEP is a zero
2816 Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
2817 SrcGEPOperands.end());
2818 Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
2821 if (!Indices.empty())
2822 return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
2824 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
2825 // GEP of global variable. If all of the indices for this GEP are
2826 // constants, we can promote this to a constexpr instead of an instruction.
2828 // Scan for nonconstants...
2829 std::vector<Constant*> Indices;
2830 User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
2831 for (; I != E && isa<Constant>(*I); ++I)
2832 Indices.push_back(cast<Constant>(*I));
2834 if (I == E) { // If they are all constants...
2835 Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices);
2837 // Replace all uses of the GEP with the new constexpr...
2838 return ReplaceInstUsesWith(GEP, CE);
2840 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(PtrOp)) {
2841 if (CE->getOpcode() == Instruction::Cast) {
2842 if (HasZeroPointerIndex) {
2843 // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
2844 // into : GEP [10 x ubyte]* X, long 0, ...
2846 // This occurs when the program declares an array extern like "int X[];"
2848 Constant *X = CE->getOperand(0);
2849 const PointerType *CPTy = cast<PointerType>(CE->getType());
2850 if (const PointerType *XTy = dyn_cast<PointerType>(X->getType()))
2851 if (const ArrayType *XATy =
2852 dyn_cast<ArrayType>(XTy->getElementType()))
2853 if (const ArrayType *CATy =
2854 dyn_cast<ArrayType>(CPTy->getElementType()))
2855 if (CATy->getElementType() == XATy->getElementType()) {
2856 // At this point, we know that the cast source type is a pointer
2857 // to an array of the same type as the destination pointer
2858 // array. Because the array type is never stepped over (there
2859 // is a leading zero) we can fold the cast into this GEP.
2860 GEP.setOperand(0, X);
2870 Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
2871 // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
2872 if (AI.isArrayAllocation()) // Check C != 1
2873 if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
2874 const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
2875 AllocationInst *New = 0;
2877 // Create and insert the replacement instruction...
2878 if (isa<MallocInst>(AI))
2879 New = new MallocInst(NewTy, 0, AI.getName());
2881 assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
2882 New = new AllocaInst(NewTy, 0, AI.getName());
2885 InsertNewInstBefore(New, AI);
2887 // Scan to the end of the allocation instructions, to skip over a block of
2888 // allocas if possible...
2890 BasicBlock::iterator It = New;
2891 while (isa<AllocationInst>(*It)) ++It;
2893 // Now that I is pointing to the first non-allocation-inst in the block,
2894 // insert our getelementptr instruction...
2896 std::vector<Value*> Idx(2, Constant::getNullValue(Type::IntTy));
2897 Value *V = new GetElementPtrInst(New, Idx, New->getName()+".sub", It);
2899 // Now make everything use the getelementptr instead of the original
2901 return ReplaceInstUsesWith(AI, V);
2904 // If alloca'ing a zero byte object, replace the alloca with a null pointer.
2905 // Note that we only do this for alloca's, because malloc should allocate and
2906 // return a unique pointer, even for a zero byte allocation.
2907 if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
2908 TD->getTypeSize(AI.getAllocatedType()) == 0)
2909 return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
2914 Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
2915 Value *Op = FI.getOperand(0);
2917 // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
2918 if (CastInst *CI = dyn_cast<CastInst>(Op))
2919 if (isa<PointerType>(CI->getOperand(0)->getType())) {
2920 FI.setOperand(0, CI->getOperand(0));
2924 // If we have 'free null' delete the instruction. This can happen in stl code
2925 // when lots of inlining happens.
2926 if (isa<ConstantPointerNull>(Op))
2927 return EraseInstFromFunction(FI);
2933 /// GetGEPGlobalInitializer - Given a constant, and a getelementptr
2934 /// constantexpr, return the constant value being addressed by the constant
2935 /// expression, or null if something is funny.
2937 static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
2938 if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
2939 return 0; // Do not allow stepping over the value!
2941 // Loop over all of the operands, tracking down which value we are
2943 gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
2944 for (++I; I != E; ++I)
2945 if (const StructType *STy = dyn_cast<StructType>(*I)) {
2946 ConstantUInt *CU = cast<ConstantUInt>(I.getOperand());
2947 assert(CU->getValue() < STy->getNumElements() &&
2948 "Struct index out of range!");
2949 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
2950 C = CS->getOperand(CU->getValue());
2951 } else if (isa<ConstantAggregateZero>(C)) {
2952 C = Constant::getNullValue(STy->getElementType(CU->getValue()));
2956 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
2957 const ArrayType *ATy = cast<ArrayType>(*I);
2958 if ((uint64_t)CI->getRawValue() >= ATy->getNumElements()) return 0;
2959 if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
2960 C = CA->getOperand(CI->getRawValue());
2961 else if (isa<ConstantAggregateZero>(C))
2962 C = Constant::getNullValue(ATy->getElementType());
2971 static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
2972 User *CI = cast<User>(LI.getOperand(0));
2974 const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
2975 if (const PointerType *SrcTy =
2976 dyn_cast<PointerType>(CI->getOperand(0)->getType())) {
2977 const Type *SrcPTy = SrcTy->getElementType();
2978 if (SrcPTy->isSized() && DestPTy->isSized() &&
2979 IC.getTargetData().getTypeSize(SrcPTy) ==
2980 IC.getTargetData().getTypeSize(DestPTy) &&
2981 (SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
2982 (DestPTy->isInteger() || isa<PointerType>(DestPTy))) {
2983 // Okay, we are casting from one integer or pointer type to another of
2984 // the same size. Instead of casting the pointer before the load, cast
2985 // the result of the loaded value.
2986 Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CI->getOperand(0),
2988 LI.isVolatile()),LI);
2989 // Now cast the result of the load.
2990 return new CastInst(NewLoad, LI.getType());
2996 /// isSafeToLoadUnconditionally - Return true if we know that executing a load
2997 /// from this value cannot trap. If it is not obviously safe to load from the
2998 /// specified pointer, we do a quick local scan of the basic block containing
2999 /// ScanFrom, to determine if the address is already accessed.
3000 static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
3001 // If it is an alloca or global variable, it is always safe to load from.
3002 if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
3004 // Otherwise, be a little bit agressive by scanning the local block where we
3005 // want to check to see if the pointer is already being loaded or stored
3006 // from/to. If so, the previous load or store would have already trapped,
3007 // so there is no harm doing an extra load (also, CSE will later eliminate
3008 // the load entirely).
3009 BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
3014 if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
3015 if (LI->getOperand(0) == V) return true;
3016 } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
3017 if (SI->getOperand(1) == V) return true;
3023 Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
3024 Value *Op = LI.getOperand(0);
3026 if (Constant *C = dyn_cast<Constant>(Op))
3027 if (C->isNullValue() && !LI.isVolatile()) // load null -> 0
3028 return ReplaceInstUsesWith(LI, Constant::getNullValue(LI.getType()));
3030 // Instcombine load (constant global) into the value loaded...
3031 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
3032 if (GV->isConstant() && !GV->isExternal())
3033 return ReplaceInstUsesWith(LI, GV->getInitializer());
3035 // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded...
3036 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
3037 if (CE->getOpcode() == Instruction::GetElementPtr) {
3038 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
3039 if (GV->isConstant() && !GV->isExternal())
3040 if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
3041 return ReplaceInstUsesWith(LI, V);
3042 } else if (CE->getOpcode() == Instruction::Cast) {
3043 if (Instruction *Res = InstCombineLoadCast(*this, LI))
3047 // load (cast X) --> cast (load X) iff safe
3048 if (CastInst *CI = dyn_cast<CastInst>(Op))
3049 if (Instruction *Res = InstCombineLoadCast(*this, LI))
3052 if (!LI.isVolatile() && Op->hasOneUse()) {
3053 // Change select and PHI nodes to select values instead of addresses: this
3054 // helps alias analysis out a lot, allows many others simplifications, and
3055 // exposes redundancy in the code.
3057 // Note that we cannot do the transformation unless we know that the
3058 // introduced loads cannot trap! Something like this is valid as long as
3059 // the condition is always false: load (select bool %C, int* null, int* %G),
3060 // but it would not be valid if we transformed it to load from null
3063 if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
3064 // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
3065 if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
3066 isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
3067 Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
3068 SI->getOperand(1)->getName()+".val"), LI);
3069 Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
3070 SI->getOperand(2)->getName()+".val"), LI);
3071 return new SelectInst(SI->getCondition(), V1, V2);
3074 } else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
3075 // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
3076 bool Safe = PN->getParent() == LI.getParent();
3078 // Scan all of the instructions between the PHI and the load to make
3079 // sure there are no instructions that might possibly alter the value
3080 // loaded from the PHI.
3082 BasicBlock::iterator I = &LI;
3083 for (--I; !isa<PHINode>(I); --I)
3084 if (isa<StoreInst>(I) || isa<CallInst>(I)) {
3090 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
3091 if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
3092 PN->getIncomingBlock(i)->getTerminator()))
3097 PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
3098 InsertNewInstBefore(NewPN, *PN);
3099 std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
3101 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
3102 BasicBlock *BB = PN->getIncomingBlock(i);
3103 Value *&TheLoad = LoadMap[BB];
3105 Value *InVal = PN->getIncomingValue(i);
3106 TheLoad = InsertNewInstBefore(new LoadInst(InVal,
3107 InVal->getName()+".val"),
3108 *BB->getTerminator());
3110 NewPN->addIncoming(TheLoad, BB);
3112 return ReplaceInstUsesWith(LI, NewPN);
3120 Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
3121 // Change br (not X), label True, label False to: br X, label False, True
3123 BasicBlock *TrueDest;
3124 BasicBlock *FalseDest;
3125 if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
3126 !isa<Constant>(X)) {
3127 // Swap Destinations and condition...
3129 BI.setSuccessor(0, FalseDest);
3130 BI.setSuccessor(1, TrueDest);
3134 // Cannonicalize setne -> seteq
3135 Instruction::BinaryOps Op; Value *Y;
3136 if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
3137 TrueDest, FalseDest)))
3138 if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
3139 Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
3140 SetCondInst *I = cast<SetCondInst>(BI.getCondition());
3141 std::string Name = I->getName(); I->setName("");
3142 Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
3143 Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
3144 // Swap Destinations and condition...
3145 BI.setCondition(NewSCC);
3146 BI.setSuccessor(0, FalseDest);
3147 BI.setSuccessor(1, TrueDest);
3148 removeFromWorkList(I);
3149 I->getParent()->getInstList().erase(I);
3150 WorkList.push_back(cast<Instruction>(NewSCC));
3157 Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
3158 Value *Cond = SI.getCondition();
3159 if (Instruction *I = dyn_cast<Instruction>(Cond)) {
3160 if (I->getOpcode() == Instruction::Add)
3161 if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
3162 // change 'switch (X+4) case 1:' into 'switch (X) case -3'
3163 for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
3164 SI.setOperand(i, ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
3166 SI.setOperand(0, I->getOperand(0));
3167 WorkList.push_back(I);
3175 void InstCombiner::removeFromWorkList(Instruction *I) {
3176 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
3180 bool InstCombiner::runOnFunction(Function &F) {
3181 bool Changed = false;
3182 TD = &getAnalysis<TargetData>();
3184 for (inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i)
3185 WorkList.push_back(&*i);
3188 while (!WorkList.empty()) {
3189 Instruction *I = WorkList.back(); // Get an instruction from the worklist
3190 WorkList.pop_back();
3192 // Check to see if we can DCE or ConstantPropagate the instruction...
3193 // Check to see if we can DIE the instruction...
3194 if (isInstructionTriviallyDead(I)) {
3195 // Add operands to the worklist...
3196 if (I->getNumOperands() < 4)
3197 AddUsesToWorkList(*I);
3200 I->getParent()->getInstList().erase(I);
3201 removeFromWorkList(I);
3205 // Instruction isn't dead, see if we can constant propagate it...
3206 if (Constant *C = ConstantFoldInstruction(I)) {
3207 // Add operands to the worklist...
3208 AddUsesToWorkList(*I);
3209 ReplaceInstUsesWith(*I, C);
3212 I->getParent()->getInstList().erase(I);
3213 removeFromWorkList(I);
3217 // Now that we have an instruction, try combining it to simplify it...
3218 if (Instruction *Result = visit(*I)) {
3220 // Should we replace the old instruction with a new one?
3222 DEBUG(std::cerr << "IC: Old = " << *I
3223 << " New = " << *Result);
3225 // Everything uses the new instruction now.
3226 I->replaceAllUsesWith(Result);
3228 // Push the new instruction and any users onto the worklist.
3229 WorkList.push_back(Result);
3230 AddUsersToWorkList(*Result);
3232 // Move the name to the new instruction first...
3233 std::string OldName = I->getName(); I->setName("");
3234 Result->setName(OldName);
3236 // Insert the new instruction into the basic block...
3237 BasicBlock *InstParent = I->getParent();
3238 InstParent->getInstList().insert(I, Result);
3240 // Make sure that we reprocess all operands now that we reduced their
3242 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
3243 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
3244 WorkList.push_back(OpI);
3246 // Instructions can end up on the worklist more than once. Make sure
3247 // we do not process an instruction that has been deleted.
3248 removeFromWorkList(I);
3250 // Erase the old instruction.
3251 InstParent->getInstList().erase(I);
3253 DEBUG(std::cerr << "IC: MOD = " << *I);
3255 // If the instruction was modified, it's possible that it is now dead.
3256 // if so, remove it.
3257 if (isInstructionTriviallyDead(I)) {
3258 // Make sure we process all operands now that we are reducing their
3260 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
3261 if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
3262 WorkList.push_back(OpI);
3264 // Instructions may end up in the worklist more than once. Erase all
3265 // occurrances of this instruction.
3266 removeFromWorkList(I);
3267 I->getParent()->getInstList().erase(I);
3269 WorkList.push_back(Result);
3270 AddUsersToWorkList(*Result);
3280 FunctionPass *llvm::createInstructionCombiningPass() {
3281 return new InstCombiner();