[clang] Add clang atomic control options and attribute (PR #114841)

[Hubert Tong via cfe-commits]

================
@@ -132,6 +132,12 @@ Attribute Changes in Clang
   This forces the global to be considered small or large in regards to the
   x86-64 code model, regardless of the code model specified for the compilation.
 
+- Introduced a new statement attribute ``[[clang::atomic]]`` that enables
+  fine-grained control over atomic code generation on a per-statement basis.
+  Supported options include ``[no_]remote_memory``,
+  ``[no_]fine_grained_memory``, and ``[no_]ignore_denormal_mode``, particularly
+  relevant for AMDGPU targets, where they map to corresponding IR metadata.
----------------
hubert-reinterpretcast wrote:

```suggestion
  ``[no_]fine_grained_memory``, and ``[no_]ignore_denormal_mode``. These are
  particularly relevant for AMDGPU targets, where they map to corresponding IR
  metadata.
```

https://github.com/llvm/llvm-project/pull/114841