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Make MaskedValueIsZero a bit more aggressive

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23677 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-10-09 22:08:50 +00:00
parent fa08fb2c78
commit 5fb0deb43a
1 changed files with 9 additions and 3 deletions
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12
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -404,11 +404,17 @@ static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask) {
switch (I->getOpcode()) {
case Instruction::And:
// (X & C1) & C2 == 0 iff C1 & C2 == 0.
if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1)))
if (ConstantExpr::getAnd(CI, Mask)->isNullValue())
if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1))) {
ConstantIntegral *C1C2 =
cast<ConstantIntegral>(ConstantExpr::getAnd(CI, Mask));
if (MaskedValueIsZero(I->getOperand(0), C1C2))
return true;
break;
}
// If either the LHS or the RHS are MaskedValueIsZero, the result is zero.
return MaskedValueIsZero(I->getOperand(1), Mask) ||
MaskedValueIsZero(I->getOperand(0), Mask);
case Instruction::Or:
case Instruction::Xor:
// If the LHS and the RHS are MaskedValueIsZero, the result is also zero.
return MaskedValueIsZero(I->getOperand(1), Mask) &&
MaskedValueIsZero(I->getOperand(0), Mask);