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author | David Tweed <david.tweed@arm.com> | 2013-03-18 11:54:44 +0000 |
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committer | David Tweed <david.tweed@arm.com> | 2013-03-18 11:54:44 +0000 |
commit | ec7eb55cc4c35318ff0ec4e04c0d42e5a65e1811 (patch) | |
tree | 552e8711a2f857dc6e99290b0d514f07ddba1fe8 /lib/IR/Constants.cpp | |
parent | b9e8678025891a3eb5431c652df541b632902fc6 (diff) | |
download | external_llvm-ec7eb55cc4c35318ff0ec4e04c0d42e5a65e1811.zip external_llvm-ec7eb55cc4c35318ff0ec4e04c0d42e5a65e1811.tar.gz external_llvm-ec7eb55cc4c35318ff0ec4e04c0d42e5a65e1811.tar.bz2 |
The optimization a + (-0.0f) -> a was being misapplied to a + (+0.0f) in the vector case (because
we weren't differntiating floating-point zeroinitializers from other zero-initializers)
which was causing problems for code relying upon a + (+0.0f) to, eg, flush denormals to
0. Make the scalar and vector cases have the same behaviour.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177279 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/IR/Constants.cpp')
-rw-r--r-- | lib/IR/Constants.cpp | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/lib/IR/Constants.cpp b/lib/IR/Constants.cpp index 0c7effb..70f7e01 100644 --- a/lib/IR/Constants.cpp +++ b/lib/IR/Constants.cpp @@ -47,6 +47,19 @@ bool Constant::isNegativeZeroValue() const { if (const ConstantFP *CFP = dyn_cast<ConstantFP>(this)) return CFP->isZero() && CFP->isNegative(); + // Equivalent for a vector of -0.0's. + if (const ConstantDataVector *CV = dyn_cast<ConstantDataVector>(this)) + if (ConstantFP *SplatCFP = dyn_cast_or_null<ConstantFP>(CV->getSplatValue())) + if (SplatCFP && SplatCFP->isZero() && SplatCFP->isNegative()) + return true; + + // However, vectors of zeroes which are floating point represent +0.0's. + if (const ConstantAggregateZero *CAZ = dyn_cast<ConstantAggregateZero>(this)) + if (const VectorType *VT = dyn_cast<VectorType>(CAZ->getType())) + if (VT->getElementType()->isFloatingPointTy()) + // As it's a CAZ, we know it's the zero bit-pattern (ie, +0.0) in each element. + return false; + // Otherwise, just use +0.0. return isNullValue(); } |