[llvm] [AArch64][SME2] Extend SMEABIPass to handle functions with new ZT0 state (PR #78848)

[Sander de Smalen via llvm-commits]

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@@ -49,11 +49,13 @@ SMEAttrs::SMEAttrs(const CallBase &CB) {
 
 SMEAttrs::SMEAttrs(StringRef FuncName) : Bitmask(0) {
   if (FuncName == "__arm_tpidr2_save" || FuncName == "__arm_sme_state")
-    Bitmask |= (SMEAttrs::SM_Compatible | SMEAttrs::ZA_Preserved |
-                SMEAttrs::ZA_NoLazySave);
+    Bitmask |=
+        (SMEAttrs::SM_Compatible | SMEAttrs::ZA_Preserved |
+         SMEAttrs::ZA_NoLazySave | encodeZT0State(StateValue::Preserved));
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sdesmalen-arm wrote:

`__arm_preserves("zt0")` implies that `__arm_tpidr2_save` and `__arm_sme_state` are Shared-ZA functions, which they are not. I guess you're trying to avoid generating the spill/fill of ZT0 around the call to these functions, but perhaps that should be made part of `ZA_NoLazySave` (which then probably needs a rename).

https://github.com/llvm/llvm-project/pull/78848