[clang] [llvm] [AMDGPU][Clang] Allow amdgpu-waves-per-eu attribute to lower target occupancy range (PR #138284)

[Matt Arsenault via llvm-commits]

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@@ -2519,6 +2519,29 @@ void Verifier::verifyFunctionAttrs(FunctionType *FT, AttributeList Attrs,
       CheckFailed("invalid value for 'denormal-fp-math-f32' attribute: " + S,
                   V);
   }
+
+  if (TT.isAMDGPU()) {
+    if (auto A = Attrs.getFnAttr("amdgpu-waves-per-eu"); A.isValid()) {
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arsenm wrote:

Probably should split this into a separate function 

https://github.com/llvm/llvm-project/pull/138284