Re: [PATCH v3 4/7] x86-64: further re-work insn/suffix recognition to also cover MOVSL

[Jan Beulich <jbeulich@suse.com>]

On 11.10.2022 19:44, H.J. Lu wrote:
> On Wed, Oct 5, 2022 at 12:24 AM Jan Beulich <jbeulich@suse.com> wrote:
>>
>> PR gas/29524
>> In order to make MOVSL{,Q} behave similarly to MOVSB{W,L,Q} and
>> MOVSW{L,Q} we need to defer parse_insn()'s emitting of errors unrelated
>> to prefix parsing. Utilize i.error just like match_template() does.
> 
> Since movs{b,w,l,q} are string instructions, integer sign extensions
> require a suffix to specify the destination size.  This is different from other
> integer instructions.  Since only the new assembler allows the implicit suffix,
> it won't be easy to use.  We should improve error messages, but allowing
> new syntax doesn't help much.

It is an earlier change making most of this consistent with MOVZ*; it is
only logical to extend this to the long-to-quad sign-extending insn. As
with any fixes to prior misbehavior - of course one needs to play by the
rules of the older assembler for a number of years. But projects raise
their baselines, and hence at some point projects with an "avoid suffixes
if possible" policy could switch.

Jan