[clang] [Clang][HIP][CUDA] Add `__cluster_dims__` and `__no_cluster__` attribute (PR #156686)

[Matt Arsenault via cfe-commits]

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@@ -1557,6 +1557,23 @@ def HIPManaged : InheritableAttr {
   let Documentation = [HIPManagedAttrDocs];
 }
 
+def CUDAClusterDims : InheritableAttr {
+  let Spellings = [GNU<"cluster_dims">, Declspec<"__cluster_dims__">];
+  let Args = [ExprArgument<"X">, ExprArgument<"Y", 1>, ExprArgument<"Z", 1>];
+  let Subjects = SubjectList<[Function], ErrorDiag, "kernel functions">;
+  let LangOpts = [CUDA];
+  let Documentation = [CUDAClusterDimsAttrDoc];
+}
+
+def CUDANoCluster : InheritableAttr {
+  let Spellings = [GNU<"no_cluster">, Declspec<"__no_cluster__">];
+  let Subjects = SubjectList<[Function], ErrorDiag, "kernel functions">;
+  let LangOpts = [CUDA];
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arsenm wrote:

I'd leave it, the fewer arbitrary restrictions the better 

https://github.com/llvm/llvm-project/pull/156686