[Bug target/94515] aarch64: broken unwind information for pac-ret

["nsz at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94515

--- Comment #1 from nsz at gcc dot gnu.org ---
i had a fix but it's not enough, so here is another test case:

__attribute__((noreturn)) void unwind(void);
int bar(void);
int global;

int foo(int x)
{
  if (x==1) return 2;
  int y = bar();
  if (y > global) global=y;
  if (y==3) unwind();
  return 0;
}

-O2 -S -mbranch-protection=pac-ret the asm:

foo:
        .cfi_startproc
        cmp     w0, 1
        beq     .L4
        hint    25 // paciasp
        .cfi_window_save  //// pauth on
        stp     x29, x30, [sp, -16]!
        .cfi_def_cfa_offset 16
        .cfi_offset 29, -16
        .cfi_offset 30, -8
        mov     x29, sp
        bl      bar
        mov     w1, w0
        adrp    x2, .LANCHOR0
        ldr     w0, [x2, #:lo12:.LANCHOR0]
        cmp     w0, w1
        blt     .L11
.L3:
        mov     w0, 0
        cmp     w1, 3
        beq     .L12
        ldp     x29, x30, [sp], 16
        .cfi_remember_state
        .cfi_restore 30
        .cfi_restore 29
        .cfi_def_cfa_offset 0
        hint    29 // autiasp
        .cfi_window_save  //// pauth off
        ret
        .p2align 2,,3
.L11:
        .cfi_restore_state  //// pauth on
        str     w1, [x2, #:lo12:.LANCHOR0]
        b       .L3
        .p2align 2,,3
.L4:
        .cfi_def_cfa_offset 0
        .cfi_restore 29
        .cfi_restore 30
        mov     w0, 2  //// pauth should be off but it's on 
        ret
.L12:
        .cfi_def_cfa_offset 16
        .cfi_offset 29, -16
        .cfi_offset 30, -8
        bl      unwind
        .cfi_endproc