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

[Sander de Smalen via llvm-commits]

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@@ -164,18 +164,25 @@ define void @zt0_in_caller_zt0_new_callee() "aarch64_in_zt0" nounwind {
 define void @zt0_new_caller() "aarch64_new_zt0" nounwind {
 ; CHECK-LABEL: zt0_new_caller:
 ; CHECK:       // %bb.0: // %prelude
-; CHECK-NEXT:    str x30, [sp, #-16]! // 8-byte Folded Spill
+; CHECK-NEXT:    sub sp, sp, #80
+; CHECK-NEXT:    str x30, [sp, #64] // 8-byte Folded Spill
 ; CHECK-NEXT:    mrs x8, TPIDR2_EL0
 ; CHECK-NEXT:    cbz x8, .LBB6_2
 ; CHECK-NEXT:  // %bb.1: // %save.za
+; CHECK-NEXT:    mov x8, sp
+; CHECK-NEXT:    str zt0, [x8]
+; CHECK-NEXT:    smstop za
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sdesmalen-arm wrote:

I don't think it's valid to `smstop za` before caling `__arm_tpidr2_save` if there is an active lazy-save buffer set up. This leads to a state that is not defined in the ABI.

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