[PATCH] D71726: Let clang atomic builtins fetch add/sub support floating point types

[Yaxun Liu via Phabricator via cfe-commits]

yaxunl added a comment.

This patch focuses on clang work for enabling fp atomics. There is a middle end pass for lowering fp atomics to cmpxchg, however not all targets enable it or enable it properly. From clang point of view, those targets are not ready to say they support fp atomics, therefore it diagnose those situations and let clang fail gracefully instead of crashing with isel failure or missing symbols in linker.

I have limited resources to work on middle end and backend for all targets. If a backend really cares about fp atomics, they should fix the atomic lowering pass then enable fp atomics support in clang Target info.

This patch implements fp atomic support in clang. It does not make things worse in regarding the bugs in middle ends and backends. I think it is not beneficial to blocking this clang change due to middle end and backend issues.


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  https://reviews.llvm.org/D71726/new/

https://reviews.llvm.org/D71726