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

[Erich Keane via cfe-commits]

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@@ -5654,6 +5654,130 @@ static void handleLaunchBoundsAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
                         AL.getNumArgs() > 2 ? AL.getArgAsExpr(2) : nullptr);
 }
 
+static std::pair<Expr *, int>
+makeClusterDimsArgExpr(Sema &S, Expr *E, const CUDAClusterDimsAttr &AL,
+                       const unsigned Idx) {
+  if (S.DiagnoseUnexpandedParameterPack(E))
+    return {nullptr, 0};
+
+  // Accept template arguments for now as they depend on something else.
+  // We'll get to check them when they eventually get instantiated.
+  if (E->isValueDependent())
+    return {E, 1};
+
+  std::optional<llvm::APSInt> I = llvm::APSInt(64);
+  if (!(I = E->getIntegerConstantExpr(S.Context))) {
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erichkeane wrote:

I'd prefer splitting this into 2 lines:  Put the `E->getIntegerConstantExpr` in the initializer above, then just do `!I`. here.

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