[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.

1 files changed, 4 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 0cfe7a0..01b042c 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -2380,8 +2380,10 @@ void CodeGenModule::SetLLVMFunctionAttributesForDefinition(const Decl *D,
   if (D->hasAttr<ArmLocallyStreamingAttr>())
     B.addAttribute("aarch64_pstate_sm_body");
 
-  if (D->hasAttr<ArmNewZAAttr>())
-    B.addAttribute("aarch64_pstate_za_new");
+  if (auto *Attr = D->getAttr<ArmNewAttr>()) {
+    if (Attr->isNewZA())
+      B.addAttribute("aarch64_pstate_za_new");
+  }
 
   // Track whether we need to add the optnone LLVM attribute,
   // starting with the default for this optimization level.