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Instcombine: X * -1 -> -X

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6904 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-06-25 17:09:20 +00:00
parent 5db61fdc8a
commit 0af1fab019
1 changed files with 4 additions and 3 deletions
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7
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -361,10 +361,11 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
const Type *Ty = CI->getType();
uint64_t Val = Ty->isSigned() ?
(uint64_t)cast<ConstantSInt>(CI)->getValue() :
cast<ConstantUInt>(CI)->getValue();
int64_t Val = Ty->isSigned() ? cast<ConstantSInt>(CI)->getValue() :
(int64_t)cast<ConstantUInt>(CI)->getValue();
switch (Val) {
case -1: // X * -1 -> -X
return BinaryOperator::createNeg(Op0, I.getName());
case 0:
return ReplaceInstUsesWith(I, Op1); // Eliminate 'mul double %X, 0'
case 1: