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

[James Y Knight via Phabricator via cfe-commits]

jyknight added a comment.

In D71726#2537101 <https://reviews.llvm.org/D71726#2537101>, @yaxunl wrote:

> For amdgpu target, we do need diagnose unsupported atomics (not limited to fp atomics) since we do not support libcall due to ISA level linking not supported. This is something we cannot fix in a short time and we would rather diagnose it than confusing the users with missing symbols in lld.

If this is limited simply to not supporting oversized or misaligned atomics, I'd find that a lot less objectionable. At that point you just need a single boolean variable/accessor for whether the target can support atomic library calls. I note that we already have warning messages: warn_atomic_op_misaligned and warn_atomic_op_oversized. Maybe those can just be promoted to errors on AMDGPU.


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