Re: [PATCH] x86: infer No_*Suf from other insn attributes

[Jan Beulich <jbeulich@suse.com>]

On 17.11.2022 02:54, H.J. Lu wrote:
> On Mon, Nov 14, 2022 at 11:27 PM Jan Beulich <jbeulich@suse.com> wrote:
>>
>> On 15.11.2022 00:33, H.J. Lu wrote:
>>> On Mon, Nov 14, 2022 at 8:12 AM Jan Beulich <jbeulich@suse.com> wrote:
>>>> --- a/opcodes/i386-opc.tbl
>>>> +++ b/opcodes/i386-opc.tbl
>>>> @@ -75,12 +75,17 @@
>>>>  #define Size32 Size=SIZE32
>>>>  #define Size64 Size=SIZE64
>>>>
>>>> +#define IsPrefix IsPrefix|No_bSuf|No_wSuf|No_lSuf|No_sSuf|No_qSuf|No_ldSuf
>>>> +
>>>
>>> I prefer to add
>>>
>>> #define No_Suf No_bSuf|No_wSuf|No_lSuf|No_sSuf|No_qSuf|No_ldSuf
>>>
>>> to cover more templates.
>>
>> Iirc you said so two years ago already in the context of "x86: imply
>> all No_*Suf when none is set in a template". Yet as before I don't
>> like going that route, as that still leaves clutter on the respective
>> lines (even if it's less clutter then). Plus the ultimate goal, as
>> also said back then, ought to be to move from negative to positive
>> forms. Doing things the way done here will avoid touching all those
>> lines again which are being touched here.
>>
>> As a compromise I'd accept introducing NoSuf (or No_Suf) in addition
>> to the changes done here, for use on applicable lines not touched
>> here already, and for use in the #define-s I'm adding. I'd prefer
>> this to be a separate, subsequent patch though (to limit patch size,
>> focusing on one transformation at a time. (I could introduce the new
>> macro in a prereq patch, using it for only AddrPrefixOpReg right away,
>> then have the patch here use it in the new macros, and finally add one
>> to use the new macro on the remaining applicable templates.)
> 
> An explicit NoSuf (or No_Suf) is better.

But why? As said - once switching to expressing permitted suffixes in a
"positive" way that'll lead to touching again _all_ the templates I'm
touching here (and of course many more I'm not touching here). Plus
that's still one more item on (often long) lines which don't really need
it. Plus, just to restate what the description says, we're already doing
this with AddrPrefixOpReg.

I'd really like to see a way forward here - this is now my 2nd attempt
that you're in the process of rejecting. If you insist on going the
NoSuf-everywhere route (and hence you're not willing to accept the
suggested compromise), then may I please ask that you make such a patch
(within a reasonable time frame), for me to then re-base over? I'm not
going to submit patches which I see clear downsides with. Yet further
work I have pending wants this sorted (at least to limit patch size
some). To be specific, I'm meaning to eliminate the bogus
LONG_DOUBLE_MNEM_SUFFIX and then also No_ldSuf, which prior to the patch
here means touching about every insn template. Yet even beyond that
the size of many patches I have pending benefits from this size / line
length reduction, just like the opcode table itself does.

Jan