[llvm] [NVPTX] Add Volta Atomic SequentiallyConsistent Load and Store Operations (PR #98551)

[Artem Belevich via llvm-commits]

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@@ -106,15 +106,49 @@ enum LoadStore {
   isStoreShift = 6
 };
 
-namespace PTXLdStInstCode {
-enum MemorySemantic {
+// Extends LLVM AtomicOrdering with PTX Orderings:
+using OrderingUnderlyingType = unsigned int;
+enum class Ordering : OrderingUnderlyingType {
   NotAtomic = 0, // PTX calls these: "Weak"
-  Volatile = 1,
+  // Unordered = 1, // NVPTX maps LLVM Unorderd to Relaxed
   Relaxed = 2,
-  Acquire = 3,
-  Release = 4,
-  RelaxedMMIO = 5
+  // Consume = 3,   // Unimplemented in LLVM; NVPTX would map to "Acquire"
+  Acquire = 4,
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Artem-B wrote:

OK. The only problem is that hardcoded numbers may eventually deviate from the values used by `AtomicOrdering`.
Perhaps instead of the literal values, we should use `AtomicOrdering` enum values, possibly with a set of static asserts ensuring that the values in this enum are strictly ordered, if we rely on that.

https://github.com/llvm/llvm-project/pull/98551