diff options
Diffstat (limited to 'lib/Transforms/InstCombine/InstCombineSelect.cpp')
-rw-r--r-- | lib/Transforms/InstCombine/InstCombineSelect.cpp | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineSelect.cpp b/lib/Transforms/InstCombine/InstCombineSelect.cpp index 9a41e4b940..caf9e6af7d 100644 --- a/lib/Transforms/InstCombine/InstCombineSelect.cpp +++ b/lib/Transforms/InstCombine/InstCombineSelect.cpp @@ -365,7 +365,15 @@ 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 -static Value *foldSelectICmpAndOr(const SelectInst &SI, Value *TrueVal, +/// +/// 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, Value *FalseVal, InstCombiner::BuilderTy *Builder) { const ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition()); @@ -384,6 +392,25 @@ static Value *foldSelectICmpAndOr(const 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) |