[clang] [llvm] [AMDGPU] Add amdgpu-as MMRA for fences (PR #78572)

[Pierre van Houtryve via cfe-commits]

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@@ -18365,6 +18366,28 @@ Value *CodeGenFunction::EmitHLSLBuiltinExpr(unsigned BuiltinID,
   return nullptr;
 }
 
+void CodeGenFunction::AddAMDGCNFenceAddressSpaceMMRA(llvm::Instruction *Inst,
+                                                     const CallExpr *E) {
+  constexpr const char *Tag = "amdgpu-as";
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Pierre-vh wrote:

I think it's just more readable this way, but I have no strong preference either.
I'd say let's keep it this way, it can very easily be renamed later if we want to.

https://github.com/llvm/llvm-project/pull/78572