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Differential D36382

[InstCombine] Remove shift handling from OptAndOp.
ClosedPublic

Authored by craig.topper on Aug 6 2017, 3:31 PM.

Details

Reviewers
spatel
davide
Commits
rG576fb91aefa3: [InstCombine] Remove shift handling from OptAndOp.
rL310234: [InstCombine] Remove shift handling from OptAndOp.
Summary

This is all handled by SimplifyDemandedBits.

Diff Detail

Event Timeline

craig.topper created this revision.Aug 6 2017, 3:31 PM
Harbormaster completed remote builds in B9077: Diff 109941.Aug 6 2017, 3:32 PM
davide accepted this revision.Aug 6 2017, 4:08 PM
davide added a subscriber: davide.

LGTM.

This revision is now accepted and ready to land.Aug 6 2017, 4:08 PM
Closed by commit rL310234: [InstCombine] Remove shift handling from OptAndOp. (authored by ctopper). · Explain WhyAug 6 2017, 4:31 PM
This revision was automatically updated to reflect the committed changes.

Revision Contents

PathSize
lib/
Transforms/
InstCombine/
58 lines

Diff 109941

lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

Show First 20 Lines • Show All 176 Lines • ▼ Show 20 Lines if (Op->hasOneUse()) {
Value *NewAnd = Builder.CreateAnd(X, AndRHS); Value *NewAnd = Builder.CreateAnd(X, AndRHS);
NewAnd->takeName(Op); NewAnd->takeName(Op);
return BinaryOperator::CreateXor(NewAnd, AndRHS); return BinaryOperator::CreateXor(NewAnd, AndRHS);
} }
} }
} }
} }
break; break;
case Instruction::Shl: {
// We know that the AND will not produce any of the bits shifted in, so if
// the anded constant includes them, clear them now!
//
uint32_t BitWidth = AndRHS->getType()->getBitWidth();
uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal));
ConstantInt *CI = Builder.getInt(AndRHS->getValue() & ShlMask);
if (CI->getValue() == ShlMask)
// Masking out bits that the shift already masks.
return replaceInstUsesWith(TheAnd, Op); // No need for the and.
if (CI != AndRHS) { // Reducing bits set in and.
TheAnd.setOperand(1, CI);
return &TheAnd;
}
break;
}
case Instruction::LShr: {
// We know that the AND will not produce any of the bits shifted in, so if
// the anded constant includes them, clear them now! This only applies to
// unsigned shifts, because a signed shr may bring in set bits!
//
uint32_t BitWidth = AndRHS->getType()->getBitWidth();
uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
ConstantInt *CI = Builder.getInt(AndRHS->getValue() & ShrMask);
if (CI->getValue() == ShrMask)
// Masking out bits that the shift already masks.
return replaceInstUsesWith(TheAnd, Op);
if (CI != AndRHS) {
TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
return &TheAnd;
}
break;
}
case Instruction::AShr:
// Signed shr.
// See if this is shifting in some sign extension, then masking it out
// with an and.
if (Op->hasOneUse()) {
uint32_t BitWidth = AndRHS->getType()->getBitWidth();
uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
Constant *C = Builder.getInt(AndRHS->getValue() & ShrMask);
if (C == AndRHS) { // Masking out bits shifted in.
// (Val ashr C1) & C2 -> (Val lshr C1) & C2
// Make the argument unsigned.
Value *ShVal = Op->getOperand(0);
ShVal = Builder.CreateLShr(ShVal, OpRHS, Op->getName());
return BinaryOperator::CreateAnd(ShVal, AndRHS, TheAnd.getName());
}
}
break;
} }
return nullptr; return nullptr;
} }
/// Emit a computation of: (V >= Lo && V < Hi) if Inside is true, otherwise /// Emit a computation of: (V >= Lo && V < Hi) if Inside is true, otherwise
/// (V < Lo || V >= Hi). This method expects that Lo <= Hi. IsSigned indicates /// (V < Lo || V >= Hi). This method expects that Lo <= Hi. IsSigned indicates
/// whether to treat V, Lo, and Hi as signed or not. /// whether to treat V, Lo, and Hi as signed or not.
Value *InstCombiner::insertRangeTest(Value *V, const APInt &Lo, const APInt &Hi, Value *InstCombiner::insertRangeTest(Value *V, const APInt &Lo, const APInt &Hi,
▲ Show 20 Lines • Show All 2,340 Lines • Show Last 20 Lines