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| author | Cameron McInally <cameron.mcinally@nyu.edu> | 2019-05-15 14:31:33 +0000 |
|---|---|---|
| committer | Cameron McInally <cameron.mcinally@nyu.edu> | 2019-05-15 14:31:33 +0000 |
| commit | 0c82d9b5a2e2eaf19eeb41abaa61646f0de7bec1 (patch) | |
| tree | 21968e3758ea9728c82d3b041ed586ec07eb375f /llvm/lib/Analysis/InstructionSimplify.cpp | |
| parent | eaf4413d2d9d598f093e8c8e84bc01dd33a089e4 (diff) | |
| download | bcm5719-llvm-0c82d9b5a2e2eaf19eeb41abaa61646f0de7bec1.tar.gz bcm5719-llvm-0c82d9b5a2e2eaf19eeb41abaa61646f0de7bec1.zip | |
Teach InstSimplify -X + X --> 0.0 about unary FNeg
Differential Revision: https://reviews.llvm.org/D61916
llvm-svn: 360777
Diffstat (limited to 'llvm/lib/Analysis/InstructionSimplify.cpp')
| -rw-r--r-- | llvm/lib/Analysis/InstructionSimplify.cpp | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp index febc1d5fe9b..770fdf9054c 100644 --- a/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -4316,16 +4316,22 @@ static Value *SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI))) return Op0; - // With nnan: (+/-0.0 - X) + X --> 0.0 (and commuted variant) + // With nnan: -X + X --> 0.0 (and commuted variant) // We don't have to explicitly exclude infinities (ninf): INF + -INF == NaN. // Negative zeros are allowed because we always end up with positive zero: // X = -0.0: (-0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0 // X = -0.0: ( 0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0 // X = 0.0: (-0.0 - ( 0.0)) + ( 0.0) == (-0.0) + ( 0.0) == 0.0 // X = 0.0: ( 0.0 - ( 0.0)) + ( 0.0) == ( 0.0) + ( 0.0) == 0.0 - if (FMF.noNaNs() && (match(Op0, m_FSub(m_AnyZeroFP(), m_Specific(Op1))) || - match(Op1, m_FSub(m_AnyZeroFP(), m_Specific(Op0))))) - return ConstantFP::getNullValue(Op0->getType()); + if (FMF.noNaNs()) { + if (match(Op0, m_FSub(m_AnyZeroFP(), m_Specific(Op1))) || + match(Op1, m_FSub(m_AnyZeroFP(), m_Specific(Op0)))) + return ConstantFP::getNullValue(Op0->getType()); + + if (match(Op0, m_FNeg(m_Specific(Op1))) || + match(Op1, m_FNeg(m_Specific(Op0)))) + return ConstantFP::getNullValue(Op0->getType()); + } // (X - Y) + Y --> X // Y + (X - Y) --> X |
