Sander de Smalen 8e7f073eb4 [Clang][AArch64] Change SME attributes for shared/new/preserved state. (#76971) ...

This patch replaces the `__arm_new_za`, `__arm_shared_za` and
`__arm_preserves_za` attributes in favour of:
* `__arm_new("za")`
* `__arm_in("za")`
* `__arm_out("za")`
* `__arm_inout("za")`
* `__arm_preserves("za")`

As described in https://github.com/ARM-software/acle/pull/276.

One change is that `__arm_in/out/inout/preserves(S)` are all mutually
exclusive, whereas previously it was fine to write `__arm_shared_za
__arm_preserves_za`. This case is now represented with `__arm_in("za")`.

The current implementation uses the same LLVM attributes under the hood,
since `__arm_in/out/inout` are all variations of "shared ZA", so can use
the existing `aarch64_pstate_za_shared` attribute in LLVM.

#77941 will add support for the new "zt0" state as introduced
with SME2.

2024-01-15 09:41:32 +00:00

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