[clang] [llvm] [SPIR-V] Encode Atomic metadata as UserSemantic string decoration (PR #193019)

[Nick Sarnie via cfe-commits]

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@@ -2539,6 +2539,28 @@ void SPIRVEmitIntrinsics::insertSpirvDecorations(Instruction *I,
                       {I->getType()},
                       {I, MetadataAsValue::get(I->getContext(), MD)});
   }
+  if (I->getModule()->getTargetTriple().getVendor() == Triple::AMD &&
+      isa<AtomicRMWInst>(I)) {
+    // If present, we encode AMDGPU atomic metadata as UserSemantic string
+    // decorations, which will be parsed during reverse translation.
+    auto &Ctx = B.getContext();
+    auto *US = ConstantAsMetadata::get(
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sarnex wrote:

The spec proposal was technically redacted, if you want to propose something again I can dig it up for a reference

https://github.com/llvm/llvm-project/pull/193019