[llvm] [Docs][AMDGPU] availability/visibility in addrspace(3) (PR #212707)

[Krzysztof Drewniak via llvm-commits]

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@@ -126,19 +126,44 @@ these necessary conditions, and hence they can be explained using the rules from
 either memory model. But the new intrinsics and metadata *opt out* of the LLVM
 memory model, and can only be explained using the AMDGPU memory model.
 
+:::{note}
+We introduce new intrinsics because metadata cannot be used to express the
+availability and visibility of ordinary
+load/store operations, because the scope is necessary for correctness. In a
+hypothetical operation like this:
+
+```llvm
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krzysz00 wrote:

Post-merge note that this feels like an argument for allowing some flavor of "operand bundle" / "non-droppable hint" on load/store/...

https://github.com/llvm/llvm-project/pull/212707