[PATCH] D135097: Remove redundant option '-menable-unsafe-fp-math'.

Thu Oct 13 07:03:36 PDT 2022

aaron.ballman added a reviewer: clang-vendors.
aaron.ballman added a comment.

Adding clang-vendors because of the potential for disruption from the changes.

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Comment at: clang/docs/ReleaseNotes.rst:410-412
+- The driver option ``-menable-unsafe-fp-math`` has been removed. Passing it, will
+result in a hard error. To enable unsafe floating-point optimizations, the compiler
+options ``-funsafe-math-optimizations`` and ``-ffast-math`` are used instead.
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Because we diagnose unknown driver flags as an error (https://godbolt.org/z/4xjzKh4Ej) and there's no deprecation period, I think we should put this under the potentially breaking changes section. In this case, I'm specifically worried about proprietary projects using the flag for optimization purposes (a lot of numerical analysis code is behind closed doors).

CC @MaskRay just to make sure there's agreement (we're still trying to figure out what constitutes a breaking change we want to be loud about in terms of driver flags).

Assuming Fangrui doesn't disagree, once this lands, please post an announcement about it into https://discourse.llvm.org/c/announce/46 with the `clang` and `potentially-breaking` tags (an example of such a post is: https://discourse.llvm.org/t/clang-16-notice-of-potentially-breaking-changes/65562/ though you wouldn't need all that lead-in text). 

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D135097/new/

https://reviews.llvm.org/D135097