[PATCH] D82499: [DAGCombiner] tighten constraints for fma fold

[Qiu Chaofan via Phabricator via llvm-commits]

qiucf added a comment.

> Let me know if I should post a patch for that or if you are already working on it.

Yes. I posted D89527 <https://reviews.llvm.org/D89527>.

> It does look like gcc makes some distinction between "unsafe" and FP-contraction, but it does not behave the way I was expecting: https://godbolt.org/z/EfhPYT

The way compiler handles the option might be somewhat confusing: https://stackoverflow.com/questions/43352510 Besides, since GCC doesn't support pragma `FP_CONTRACT` (`#pragma STDC FP_CONTRACT ON`) well, `-ffp-contract=on` is equivalent to `-ffp-contract=off` in GCC. Clang looks to handle it correctly.


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  https://reviews.llvm.org/D82499/new/

https://reviews.llvm.org/D82499