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

[Jan Beulich <jbeulich@suse.com>]

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).

Jan