[llvm] [AArch64][Bitcode] Use target memory for SME state (PR #205829)

[Paul Walker via llvm-commits]

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@@ -2292,8 +2292,7 @@ For example:
     - ``errnomem``: This refers to accesses to the ``errno`` variable.
     - ``target_mem#`` : These refer to target specific state that cannot be
       accessed by any other means. # is a number between 0 and 1 inclusive.
-      Note: The target_mem locations are experimental and intended for internal
-      testing only. They must not be used in production code.
+      Note: The target_mem locations are implemented in AArch64.
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paulwalker-arm wrote:

We should be specific here because otherwise those unfamiliar cannot interpret the IR.  Something like "Note: Aarch64 uses target_mem0 to represent SME ZT state, target_mem1 to .........., all other uses of target_mem are not defined."

https://github.com/llvm/llvm-project/pull/205829