[clang] [llvm] [AMDGPU] Add an option to disable unsafe uses of atomic xor (PR #69229)

[Matt Arsenault via cfe-commits]

arsenm wrote:

> Will the metadata for unsafe-fp-atomics also be controlled by the pragma that controls the no-fine-grained and no-remote metadata? e.g. something like
> 
> ```
> #pragma clang atomics begin no-fine-grained(on) no-remote(on) unsafe-fp(on)
> ```

Yes, I would expect something like that for consistency. The most problematic part is the denormal flushing in some address spaces, and secondarily the fixed rounding mode in other cases 

https://github.com/llvm/llvm-project/pull/69229