[PATCH] x86: fold special-operand insn attributes into a single enum

[H.J. Lu]

On Fri, Nov 11, 2022 at 12:22 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> On 11.11.2022 09:00, Jan Beulich via Binutils wrote:
> > On 10.11.2022 18:38, H.J. Lu wrote:
> >> On Thu, Nov 10, 2022 at 5:45 AM Jan Beulich <jbeulich@suse.com> wrote:
> >>>
> >>> Attributes which aren't used together in any single insn template can be
> >>> converted from individual booleans to a single enum, as was done for a few
> >>> other attributes before. This is more space efficient. Collect together
> >>> all attributes which express special operand constraints (and which fit
> >>> the criteria for folding).
> >>
> >> These assumptions may not be all true for future new instructions.
> >
> > It seems pretty unlikely to me that any of these assumptions would break.
> > If one does, converting back to an individual bit is an easy option. I
> > think this minor risk is far outweighed by the benefits of the change. We
> > really have still some ways to go to reach reasonable data representation
> > within the generated opcode table (and of course also in the source table,
> > but that's an orthogonal direction of work, where I also have further
> > changes pending).
>
> I should probably expand: For most of these I don't expect new uses to appear
> at all. Note also that I left alone e.g. ImmExt, for having a bigger risk of
> a new conflicting use appearing.
>
> If you have concerns for a specific attribute, please voice it that way. I'm
> certainly willing to re-consider for individual attributes (albeit as said
> in the earlier reply, the way back for any individual one is easy); I'm not
> going to accept a blanket "no".
>
> Jan

Lingling, Lili, Haochen, do you have any comments?

Thanks.

-- 
H.J.