maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

Make MaskedValueIsZero a bit more aggressive 

llvm-svn: 23677
This commit is contained in:
Chris Lattner 2005-10-09 22:08:50 +00:00
parent 1dfb85c7af
commit 03b9eb506c
1 changed files with 9 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -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);