https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121253
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2025-07-26
CC| |pinskia at gcc dot gnu.org
Keywords|ra |
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
Known to fail| |15.1.0
Target Milestone|--- |14.4
Summary|aarch64 inline asm: 128-bit |[14/15/16 Regression]
|output operands use |aarch64 inline asm: 128-bit
|clobbered registers |output operands use
| |clobbered registers
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.
Note looks like the problem is latent in GCC 14; just a cost model change
exposed it.
>From gcc14's forwprop1:
```
successfully matched this instruction:
(set (reg/i:TI 0 x0)
(asm_operands:TI ("mov %0, #0
mov %R0, #0
mov x0, #12345") ("=r") 0 []
[]
[] /app/example.cpp:8))
change not profitable (cost 0 -> cost 4)
```
That is the clobber is gone. We should NOT be removing clobbers from
inline-asm.
In GCC 13, forwprop1 was different and didn't try it.
I think rtl-ssa infrastructure is removing the clobbers.
