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Revert r88830 and r88831 which appear to have caused a selfhost buildbot some

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grief. I suspect this patch merely exposed a bug else.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@88841 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2009-11-15 07:47:32 +00:00
parent 048bac35df
commit feb8018764
2 changed files with 1 additions and 28 deletions
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28
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -8539,34 +8539,6 @@ Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, Instruction &CI,
}
}
// icmp ne A, B is equal to xor A, B when A and B only really have one bit.
// It is also profitable to transform icmp eq into not(xor(A, B)) because that
// may lead to additional simplifications.
if (CI.getType() == ICI->getOperand(0)->getType()) {
if (const IntegerType *ITy = dyn_cast<IntegerType>(CI.getType())) {
Value *LHS = ICI->getOperand(0);
Value *RHS = ICI->getOperand(1);
uint32_t BitWidth = ITy->getBitWidth();
APInt KnownZeroLHS(BitWidth, 0), KnownOneLHS(BitWidth, 0);
APInt KnownZeroRHS(BitWidth, 0), KnownOneRHS(BitWidth, 0);
APInt TypeMask(APInt::getAllOnesValue(BitWidth));
ComputeMaskedBits(LHS, TypeMask, KnownZeroLHS, KnownOneLHS);
ComputeMaskedBits(RHS, TypeMask, KnownZeroRHS, KnownOneRHS);
if (KnownZeroLHS.countLeadingOnes() == BitWidth-1 &&
KnownZeroRHS.countLeadingOnes() == BitWidth-1) {
if (!DoXform) return ICI;
Value *Xor = Builder->CreateXor(LHS, RHS);
if (ICI->isTrueWhenEqual())
Xor = Builder->CreateXor(Xor, ConstantInt::get(ITy, 1));
Xor->takeName(ICI);
return ReplaceInstUsesWith(CI, Xor);
}
}
}
return 0;
}

1
test/Transforms/InstCombine/compare-signs.ll
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@ -1,4 +1,5 @@
; RUN: opt %s -instcombine -S | FileCheck %s
; XFAIL: *
; PR5438
; TODO: This should also optimize down.