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Pull in r222856 from upstream llvm trunk (by David Majnemer):

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Revert "Added inst combine transforms for single bit tests from Chris's note"

  This reverts commit r210006, it miscompiled libapr which is used in who
  knows how many projects.

  A test has been added to ensure that we don't regress again.

This fixes a miscompilation in libapr, which caused problems in svnlite.
This commit is contained in:
dim 2014-11-27 00:33:31 +00:00
parent 226a2bb6bf
commit d0207f44e2
1 changed files with 1 additions and 28 deletions
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29
contrib/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
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@ -387,15 +387,7 @@ static Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
/// 1. The icmp predicate is inverted
/// 2. The select operands are reversed
/// 3. The magnitude of C2 and C1 are flipped
///
/// This also tries to turn
/// --- Single bit tests:
/// if ((x & C) == 0) x |= C to x |= C
/// if ((x & C) != 0) x ^= C to x &= ~C
/// if ((x & C) == 0) x ^= C to x |= C
/// if ((x & C) != 0) x &= ~C to x &= ~C
/// if ((x & C) == 0) x &= ~C to nothing
static Value *foldSelectICmpAndOr(SelectInst &SI, Value *TrueVal,
static Value *foldSelectICmpAndOr(const SelectInst &SI, Value *TrueVal,
Value *FalseVal,
InstCombiner::BuilderTy *Builder) {
const ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition());
@ -414,25 +406,6 @@ static Value *foldSelectICmpAndOr(SelectInst &SI, Value *TrueVal,
return nullptr;
const APInt *C2;
if (match(TrueVal, m_Specific(X))) {
// if ((X & C) != 0) X ^= C becomes X &= ~C
if (match(FalseVal, m_Xor(m_Specific(X), m_APInt(C2))) && C1 == C2)
return Builder->CreateAnd(X, ~(*C1));
// if ((X & C) != 0) X &= ~C becomes X &= ~C
if (match(FalseVal, m_And(m_Specific(X), m_APInt(C2))) && *C1 == ~(*C2))
return FalseVal;
} else if (match(FalseVal, m_Specific(X))) {
// if ((X & C) == 0) X ^= C becomes X |= C
if (match(TrueVal, m_Xor(m_Specific(X), m_APInt(C2))) && C1 == C2)
return Builder->CreateOr(X, *C1);
// if ((X & C) == 0) X &= ~C becomes nothing
if (match(TrueVal, m_And(m_Specific(X), m_APInt(C2))) && *C1 == ~(*C2))
return X;
// if ((X & C) == 0) X |= C becomes X |= C
if (match(TrueVal, m_Or(m_Specific(X), m_APInt(C2))) && C1 == C2)
return TrueVal;
}
bool OrOnTrueVal = false;
bool OrOnFalseVal = match(FalseVal, m_Or(m_Specific(TrueVal), m_Power2(C2)));
if (!OrOnFalseVal)