diff options
Diffstat (limited to 'lib/Transforms/InstCombine/InstructionCombining.cpp')
-rw-r--r-- | lib/Transforms/InstCombine/InstructionCombining.cpp | 63 |
1 files changed, 46 insertions, 17 deletions
diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp index af9ec5c..ab43f7d 100644 --- a/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -710,6 +710,52 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { return 0; } + + +static bool IsOnlyNullComparedAndFreed(const Value &V) { + for (Value::const_use_iterator UI = V.use_begin(), UE = V.use_end(); + UI != UE; ++UI) { + if (isFreeCall(*UI)) + continue; + if (const ICmpInst *ICI = dyn_cast<ICmpInst>(*UI)) + if (ICI->isEquality() && isa<ConstantPointerNull>(ICI->getOperand(1))) + continue; + return false; + } + return true; +} + +Instruction *InstCombiner::visitMalloc(Instruction &MI) { + // If we have a malloc call which is only used in any amount of comparisons + // to null and free calls, delete the calls and replace the comparisons with + // true or false as appropriate. + if (IsOnlyNullComparedAndFreed(MI)) { + for (Value::use_iterator UI = MI.use_begin(), UE = MI.use_end(); + UI != UE;) { + // We can assume that every remaining use is a free call or an icmp eq/ne + // to null, so the cast is safe. + Instruction *I = cast<Instruction>(*UI); + + // Early increment here, as we're about to get rid of the user. + ++UI; + + if (isFreeCall(I)) { + EraseInstFromFunction(*cast<CallInst>(I)); + continue; + } + // Again, the cast is safe. + ICmpInst *C = cast<ICmpInst>(I); + ReplaceInstUsesWith(*C, ConstantInt::get(Type::getInt1Ty(C->getContext()), + C->isFalseWhenEqual())); + EraseInstFromFunction(*C); + } + return EraseInstFromFunction(MI); + } + return 0; +} + + + Instruction *InstCombiner::visitFree(Instruction &FI) { Value *Op = FI.getOperand(1); @@ -726,23 +772,6 @@ Instruction *InstCombiner::visitFree(Instruction &FI) { if (isa<ConstantPointerNull>(Op)) return EraseInstFromFunction(FI); - // If we have a malloc call whose only use is a free call, delete both. - if (isMalloc(Op)) { - if (CallInst* CI = extractMallocCallFromBitCast(Op)) { - if (Op->hasOneUse() && CI->hasOneUse()) { - EraseInstFromFunction(FI); - EraseInstFromFunction(*CI); - return EraseInstFromFunction(*cast<Instruction>(Op)); - } - } else { - // Op is a call to malloc - if (Op->hasOneUse()) { - EraseInstFromFunction(FI); - return EraseInstFromFunction(*cast<Instruction>(Op)); - } - } - } - return 0; } |