[Bug ada/120440] [15/16 regression] gnat exception handling miscompiled (`gnat ls` crashes when bootstrapped with -march=znver3) since r15-8901-g7bec4570301c43

[sjames at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120440

--- Comment #11 from Sam James <sjames at gcc dot gnu.org> ---
Oh:
```
(rr) p Copy
$24 = (access system.exceptions.machine.gnat_gcc_exception) 0x56314ade85a0
(rr) disas
Dump of assembler code for function
ada__exceptions__exception_propagation__gnat_gcc_exception_cleanupXn:
=> 0x000056312853b80e <+0>:     test   rsi,rsi
   0x000056312853b811 <+3>:     je     0x56312853b825
<ada__exceptions__exception_propagation__gnat_gcc_exception_cleanupXn+23>
   0x000056312853b813 <+5>:     sub    rsp,0x8
   0x000056312853b817 <+9>:     mov    rdi,QWORD PTR [rsi-0x8]
   0x000056312853b81b <+13>:    call   0x5631285713d0 <__gnat_free>
   0x000056312853b820 <+18>:    add    rsp,0x8
   0x000056312853b824 <+22>:    ret
   0x000056312853b825 <+23>:    ret
End of assembler dump.
(rr) p $rsi - 0x8
$25 = 94769709483416
(rr) p *($rsi - 0x8)
$26 = 721
```