Notices by Marc B. Reynolds (mbr@mastodon.gamedev.place)

Via a comment by @pinskia

So you can (in GCC/clang) prevent add/sub re-associations with built-ins in both. Sadly clang isn't consistently handling FMA prevention yet.

https://godbolt.org/z/c4crMh4Gf

Nice. the next GCC:

__builtin_assoc_barrier (a*b) + c

will prevent generating an FMA.

EDIT: This has been the case and it was just missing from the documentation.

https://gcc.godbolt.org/z/Kje39YeY9

@moonchild TBH: It's not clear to me. It may have but just not been documented?

@moonchild Well it appears it was just a documentation thing only!