[PATCH] x86: Optimize with EVEX128 encoding for AVX512VL

Jan Beulich JBeulich@suse.com
Thu Mar 8 16:46:00 GMT 2018


>>> On 08.03.18 at 17:08, <hjl.tools@gmail.com> wrote:
> On Thu, Mar 8, 2018 at 7:28 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>>> On 08.03.18 at 15:34, <hjl.tools@gmail.com> wrote:
>>> On Thu, Mar 8, 2018 at 6:03 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>> Do you really need that extra pseudo_evex_prefix field, i.e.
>>>> why can't you just check i.vec_encoding?
>>>>
>>>
>>> Yes, it is needed since  i.vec_encoding will be changed to
>>> vex_encoding_evex by:
>>>
>>>  /* Upper 16 vector register is only available with VREX in 64bit
>>>      mode.  */
>>>   if ((r->reg_flags & RegVRex))
>>>     {
>>>       if (i.vec_encoding == vex_encoding_default)
>>>         i.vec_encoding = vex_encoding_evex;
>>
>> But in that case you can't lower to VEX encoding anyway.
>>
> 
> You are right.  Here is the updated patch.

LGTM, FWIW.

Jan



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