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

[via llvm-commits]

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@@ -508,11 +508,40 @@ static std::optional<unsigned> convertAS(unsigned AS) {
   }
 }
 
-static unsigned int getCodeAddrSpace(const MemSDNode *N) {
+NVPTX::AddressSpace NVPTXDAGToDAGISel::getAddrSpace(const MemSDNode *N) {
   return convertAS(N->getMemOperand()->getAddrSpace())
       .value_or(NVPTX::AddressSpace::Generic);
 }
 
+NVPTX::Ordering NVPTXDAGToDAGISel::getMemOrder(const MemSDNode *N) const {
+  // No "sem" orderings for SM/PTX versions which do not support memory ordering
+  if (!Subtarget->hasMemoryOrdering())
+    return NVPTX::Ordering::NotAtomic;
+  auto Ordering = N->getMergedOrdering();
+  switch (Ordering) {
+  case AtomicOrdering::NotAtomic:
+  case AtomicOrdering::Unordered:
+    return NVPTX::Ordering::NotAtomic;
+  case AtomicOrdering::Monotonic:
+    return NVPTX::Ordering::Relaxed;
+  case AtomicOrdering::Acquire:
+    return NVPTX::Ordering::Acquire;
+  case AtomicOrdering::Release:
+    return NVPTX::Ordering::Release;
+  case AtomicOrdering::AcquireRelease:
+    return NVPTX::Ordering::AcquireRelease;
+  case AtomicOrdering::SequentiallyConsistent:
+    return NVPTX::Ordering::SequentiallyConsistent;
+  }
+}
+
+NVPTX::Scope NVPTXDAGToDAGISel::getAtomicScope(const MemSDNode *N) const {
+  // No "scope" modifier for SM/PTX versions which do not support scoped atomics
+  if (!Subtarget->hasAtomScope())
+    return NVPTX::Scope::Thread;
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gonzalobg wrote:

I think it may be better to add a `None` value to the `enum` instead.
`Thread` is what's produced from LLVM `syncscope("singlethread")`.

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