[clang] [Clang][HIP] Deprecate the AMDGCN_WAVEFRONT_SIZE macros (PR #112849)

[Matt Arsenault via cfe-commits]

================
@@ -337,9 +337,12 @@ void AMDGPUTargetInfo::getTargetDefines(const LangOptions &Opts,
   if (hasFastFMA())
     Builder.defineMacro("FP_FAST_FMA");
 
-  Builder.defineMacro("__AMDGCN_WAVEFRONT_SIZE__", Twine(WavefrontSize));
-  // ToDo: deprecate this macro for naming consistency.
-  Builder.defineMacro("__AMDGCN_WAVEFRONT_SIZE", Twine(WavefrontSize));
+  Builder.defineMacro("__AMDGCN_WAVEFRONT_SIZE__", Twine(WavefrontSize),
+                      "compile-time-constant access to the wavefront size will "
+                      "be removed in a future release");
+  Builder.defineMacro("__AMDGCN_WAVEFRONT_SIZE", Twine(WavefrontSize),
+                      "compile-time-constant access to the wavefront size will "
+                      "be removed in a future release");
----------------
arsenm wrote:

I was thinking of lower level uses. i.e. not user facing code we would want in headers or people using directly. e.g. cases where implementing cross lane operations relies on the operations that only work on half the lanes, or don't work at all when executed in wave32 

https://github.com/llvm/llvm-project/pull/112849