Re: [PATCH 0/4] x86: fold a number of VEX and EVEX templates

[Jan Beulich <jbeulich@suse.com>]

On 18.09.2023 13:18, Cui, Lili wrote:
>> -----Original Message-----
>> From: Jan Beulich <jbeulich@suse.com>
>> Sent: Monday, September 18, 2023 5:38 PM
>> To: Cui, Lili <lili.cui@intel.com>
>> Cc: Binutils <binutils@sourceware.org>; H.J. Lu <hjl.tools@gmail.com>;
>> Hongtao Liu <crazylht@gmail.com>
>> Subject: Re: [PATCH 0/4] x86: fold a number of VEX and EVEX templates
>>
>> On 18.09.2023 07:47, Cui, Lili wrote:
>>>> -----Original Message-----
>>>> From: Hongtao Liu <crazylht@gmail.com>
>>>> Sent: Monday, September 18, 2023 9:58 AM
>>>>
>>>> On Fri, Sep 15, 2023 at 4:46 PM Jan Beulich via Binutils
>>>> <binutils@sourceware.org> wrote:
>>>>>
>>>>> The last two patches are explicitly RFC, for having a possibly
>>>>> unwanted side effect.
>>>> We're about to send out APX patches, @Lili Cui  cloud you take a look
>>>> at the series?
>>>
>>> Since APX only needs to promote the VEX instructions without
>> corresponding EVEX, these folding VEX and EVEX template patches has no
>> effect on our internal APX patches.
>>
>> I don't follow: As soon as you have an insn with both a VEX and an EVEX
>> encoding, there can be potential for folding (ideally right when APX is being
>> introduced, rather than once again leaving it to me to clean up later).
> 
> Oh, I got your point. After your patches checked in,  I will fold VEX and EVEX  after we have promoted-EVEX. 

Just fyi that I'll likely need a v2 of those patches. While thinking of how
to remove the odd behavior of the latter two patches, I also spotted an
anomaly (even if largely benign right now) in the first one. I'll have to
think about that some more (just to be reasonably sure not to introduce yet
new quirks), so I won't post right away.

Jan