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

[Dhruva Chakrabarti 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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dhruvachak wrote:

Ok, so here's the enum. 

enum class SyncScope {
  SystemScope,
  DeviceScope,
  WorkgroupScope,
  WavefrontScope,
  SingleScope,
  HIPSingleThread,
  HIPWavefront,
  HIPWorkgroup,
  HIPAgent,
  HIPSystem,
  OpenCLWorkGroup,
  OpenCLDevice,
  OpenCLAllSVMDevices,
  OpenCLSubGroup,
  Last = OpenCLSubGroup
};

So like you said, the OpenCL ones. If Matt agrees, I am fine with this change though I don't see how it is better than explicitly checking for OpenCL. Just more cryptic. Either way, please add a comment.

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