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Transform X-(X+Y) == -Y and X-(Y+X) == -Y

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21134 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-04-07 16:15:25 +00:00
parent 273a1f956f
commit 43d84d6b71
1 changed files with 11 additions and 2 deletions
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13
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -792,7 +792,15 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
return NV;
}
if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1))
if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
if (Op1I->getOpcode() == Instruction::Add &&
!Op0->getType()->isFloatingPoint()) {
if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
}
if (Op1I->hasOneUse()) {
// Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
// is not used by anyone else...
@ -822,7 +830,7 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
// -(X sdiv C) -> (X sdiv -C)
if (Op1I->getOpcode() == Instruction::Div)
if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
if (CSI->getValue() == 0)
if (CSI->isNullValue())
if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
return BinaryOperator::createDiv(Op1I->getOperand(0),
ConstantExpr::getNeg(DivRHS));
@ -835,6 +843,7 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
return BinaryOperator::createMul(Op0, CP1);
}
}
}
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
if (Op0I->getOpcode() == Instruction::Add)