[libcxx-commits] [libcxx] [libc++] Implement P0493R5: Atomic minimum/maximum (PR #180333)

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c8ef wrote:

> I think clang does tried to create the builtin that looks like gcc one , but gcc does not actually have it.
> 
> ```
> // GCC does not support these, they are a Clang extension.
> def AtomicFetchMax : AtomicBuiltin {
>   let Spellings = ["__atomic_fetch_max"];
>   let Attributes = [CustomTypeChecking];
>   let Prototype = "void(...)";
> }
> ```
> 
> Given about, in the `atomic_ref` case, I wonder if we should test if the builtin exists, if so, use it , otherwise fallback to the CAS loop?

Indeed, using the builtin will simplify the implementation for clang. Done.


https://github.com/llvm/llvm-project/pull/180333