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| author | Dinesh Dwivedi <dinesh.d@samsung.com> | 2014-06-02 07:24:36 +0000 |
|---|---|---|
| committer | Dinesh Dwivedi <dinesh.d@samsung.com> | 2014-06-02 07:24:36 +0000 |
| commit | c469e543a02de7c87b6aa906d91e480ed249d8ac (patch) | |
| tree | 14d1bbbc14da5b4f08c7ed74f6b7fe8ee1feeb83 /lib/Transforms/InstCombine | |
| parent | 01fa655228c1e8460e1aaf23bc80cb669b1cefaa (diff) | |
| download | llvm-c469e543a02de7c87b6aa906d91e480ed249d8ac.tar.gz llvm-c469e543a02de7c87b6aa906d91e480ed249d8ac.tar.bz2 llvm-c469e543a02de7c87b6aa906d91e480ed249d8ac.tar.xz | |
Added inst combine transforms for single bit tests from Chris's note
if ((x & C) == 0) x |= C becomes x |= C
if ((x & C) != 0) x ^= C becomes x &= ~C
if ((x & C) == 0) x ^= C becomes x |= C
if ((x & C) != 0) x &= ~C becomes x &= ~C
if ((x & C) == 0) x &= ~C becomes nothing
Differential Revision: http://reviews.llvm.org/D3777
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210006 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms/InstCombine')
| -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) |