[llvm] [NVPTX] Add syncscope support for cmpxchg (PR #140812)

[via llvm-commits]

================
@@ -6317,10 +6317,13 @@ Instruction *NVPTXTargetLowering::emitLeadingFence(IRBuilderBase &Builder,
 
   // Specialize for cmpxchg
   // Emit a fence.sc leading fence for cmpxchg seq_cst which are not emulated
+  SyncScope::ID SSID = cast<AtomicCmpXchgInst>(Inst)->getSyncScopeID();
   if (isReleaseOrStronger(Ord))
-    return Ord == AtomicOrdering::SequentiallyConsistent
-               ? Builder.CreateFence(AtomicOrdering::SequentiallyConsistent)
-               : Builder.CreateFence(AtomicOrdering::Release);
+    return Builder.CreateFence(
+        Ord == AtomicOrdering::SequentiallyConsistent
+            ? AtomicOrdering::SequentiallyConsistent
+            : AtomicOrdering::Release,
----------------
gonzalobg wrote:

```suggestion
    return Builder.CreateFence(
        Ord == AtomicOrdering::SequentiallyConsistent
            ? AtomicOrdering::SequentiallyConsistent
            : AtomicOrdering::Release, // applies if Release or AcqRel
```

https://github.com/llvm/llvm-project/pull/140812