[llvm] Add AMDGPU metadata to copyMetadataForLoad() (PR #110720)

[Krzysztof Drewniak via llvm-commits]

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@@ -3488,6 +3490,14 @@ void llvm::copyMetadataForLoad(LoadInst &Dest, const LoadInst &Source) {
       copyRangeMetadata(DL, Source, N, Dest);
       break;
     }
+    // Extended last-use / nontemporal hint on AMD GPUs
+    if (ID == Ctx.getMDKindID("amdpu.last.use"))
+      Dest.setMetadata(ID, N);
+    // Currently only relevant to atomics
+    else if (ID == Ctx.getMDKindID("amdgpu.no.remote.memory"))
+      Dest.setMetadata(ID, N);
+    else if (ID == Ctx.getMDKindID("amdgpu.no.fine.grained.memory"))
+      Dest.setMetadata(ID, N);
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krzysz00 wrote:

So, while they're currently only related to `atomicrmw`s, I can imagine some hypothetical future where an atomic load or the like needs a `!amdgpu.no.host.memory` to avoid setting some pessimizing flag

https://github.com/llvm/llvm-project/pull/110720