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[InstCombine] Use APInt::intersects and APInt::isSubsetOf to improve a few more places in SimplifyDemandedBits. 

llvm-svn: 300896
This commit is contained in:
Craig Topper 2017-04-20 21:24:37 +00:00
parent 3f5152d212
commit ff23889609
1 changed files with 4 additions and 4 deletions
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8
llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
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@ -578,12 +578,12 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
// If the input sign bit is known to be zero, or if none of the top bits
// are demanded, turn this into an unsigned shift right.
if (BitWidth <= ShiftAmt || KnownZero[BitWidth-ShiftAmt-1] ||
(HighBits & ~DemandedMask) == HighBits) {
!DemandedMask.intersects(HighBits)) {
BinaryOperator *LShr = BinaryOperator::CreateLShr(I->getOperand(0),
I->getOperand(1));
LShr->setIsExact(cast<BinaryOperator>(I)->isExact());
return InsertNewInstWith(LShr, *I);
} else if ((KnownOne & SignMask) != 0) { // New bits are known one.
} else if (KnownOne.intersects(SignMask)) { // New bits are known one.
KnownOne |= HighBits;
}
}
@ -612,12 +612,12 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
// If LHS is non-negative or has all low bits zero, then the upper bits
// are all zero.
if (LHSKnownZero.isSignBitSet() || ((LHSKnownZero & LowBits) == LowBits))
if (LHSKnownZero.isSignBitSet() || LowBits.isSubsetOf(LHSKnownZero))
KnownZero |= ~LowBits;
// If LHS is negative and not all low bits are zero, then the upper bits
// are all one.
if (LHSKnownOne.isSignBitSet() && ((LHSKnownOne & LowBits) != 0))
if (LHSKnownOne.isSignBitSet() && LowBits.intersects(LHSKnownOne))
KnownOne |= ~LowBits;
assert(!(KnownZero & KnownOne) && "Bits known to be one AND zero?");