[PATCH 8/8] Support APX JMPABS

[Jan Beulich]

On 27.11.2023 10:03, Hu, Lin1 wrote:
>> -----Original Message-----
>> From: Jan Beulich <jbeulich@suse.com>
>> Sent: Monday, November 27, 2023 4:55 PM
>>
>> On 27.11.2023 09:46, Hu, Lin1 wrote:
>>> If I use "{evex} vaddpd ymm0, ymm1, ymm2". If it's for register considerations,
>> I think bit 5, 6, 7 can all be zero. Because the insn doesn't use k0-k7 and the
>> upper 256 bits of the registers ZMM0-ZMM15.
>>
>> How that? It clears the upper 256 bits of the destination register.
> 
> OK, so bit 5 and 7 are not affected, it they are zero, I  think the exception shouldn't be triggered.

Except that the spec mandates that the three bits are all set or all clear.
This could have been less strict, but that's too late now. For APX otoh it's
not too late yet to avoid quirky behavior.

Jan