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Fix PR1014 and InstCombine/2006-11-27-XorBug.ll.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31941 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-11-27 19:55:07 +00:00
parent e434f4ac50
commit f2f1643037
1 changed files with 8 additions and 10 deletions
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18
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -939,17 +939,15 @@ bool InstCombiner::SimplifyDemandedBits(Value *V, uint64_t DemandedMask,
// Output known-1 are known to be set if set in only one of the LHS, RHS.
uint64_t KnownOneOut = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
// If all of the unknown bits are known to be zero on one side or the other
// (but not both) turn this into an *inclusive* or.
// If all of the demanded bits are known to be zero on one side or the
// other, turn this into an *inclusive* or.
// e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
if (uint64_t UnknownBits = DemandedMask & ~(KnownZeroOut|KnownOneOut)) {
if ((UnknownBits & (KnownZero|KnownZero2)) == UnknownBits) {
Instruction *Or =
BinaryOperator::createOr(I->getOperand(0), I->getOperand(1),
I->getName());
InsertNewInstBefore(Or, *I);
return UpdateValueUsesWith(I, Or);
}
if ((DemandedMask & ~KnownZero & ~KnownZero2) == 0) {
Instruction *Or =
BinaryOperator::createOr(I->getOperand(0), I->getOperand(1),
I->getName());
InsertNewInstBefore(Or, *I);
return UpdateValueUsesWith(I, Or);
}
// If all of the demanded bits on one side are known, and all of the set