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A comment on Optimizations Enabled by -ffast-Math. Parent comment

Re:Optimizations Enabled by -ffast-Math by jcelerier on Wednesday October 20, 2021 @07:07AM (#28929271)
I was misremembering, was thinking about this recent convo on LLVM mailinglist: https://lists.llvm.org/pipermail/llvm-dev/2021-September/152...
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Re:Optimizations Enabled by -ffast-Math by usefulcat on Wednesday October 20, 2021 @12:39PM (#28932807)
I don't think you are misremembering; -ffast-math causes __builtin_isnan and __builtin_isinf to unconditionally return zero, for both gcc and clang:

https://godbolt.org/z/1qjxvW3KK

I found this out the hard way several years ago and still have my own implementations of these functions laying about in case I want to use -ffast-math.

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