[llvm-dev] [FPEnv] FNEG instruction (original) (raw)
Cameron McInally via llvm-dev llvm-dev at lists.llvm.org
Wed Sep 26 11:29:48 PDT 2018
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On Wed, Sep 26, 2018 at 2:14 PM Kevin Neal via llvm-dev < llvm-dev at lists.llvm.org> wrote:
Do we really want to have fneg be the only instruction with guaranteed no side effects? That just sounds like a gotcha waiting to happen. Or it could result in horrible code depending on the architecture.
That's not quite right. FNEG(X) and FSUB(-0.0, X) are not the same operation. They are very similar, but still different at an edge case(s). The current transformations that occur in LLVM are unsafe. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20180926/1a33880c/attachment.html>
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