[clang] [Clang][AMDGPU] Stop defaulting to `one-as` for all atomic scopes (PR #120095)

[Tony Tye via cfe-commits]

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@@ -537,7 +537,11 @@ AMDGPUTargetCodeGenInfo::getLLVMSyncScopeID(const LangOptions &LangOpts,
     break;
   }
 
-  if (Ordering != llvm::AtomicOrdering::SequentiallyConsistent) {
+  // OpenCL assumes by default that atomic scopes are per-address space for
+  // non-sequentially consistent operations.
+  if (Scope >= SyncScope::OpenCLWorkGroup &&
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t-tye wrote:

What does seem questionable is that this function is checking the memory ordering. It feels like that should be done by the caller of this function. It is the caller that should be selecting the right value for the scope argument. For OpenCL the *one-as" sync-scopes should only be used for non-sequentially consistent memory orders. That is is rule of the OpenCL language.

https://github.com/llvm/llvm-project/pull/120095