Re: [PATCH 0/2] x86: Fix the -mevexwig=1 assembler option

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Mon, Sep 17, 2018 at 5:14 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>> On 16.09.18 at 14:15, <hjl.tools@gmail.com> wrote:
>> On Sun, Sep 16, 2018 at 2:38 AM, Jan Beulich <jbeulich@suse.com> wrote:
>>>>>> "H.J. Lu" <hjl.tools@gmail.com> 09/14/18 9:14 PM >>>
>>>>The VEX.W/EVEX.W bit is ignored by some VEX/EVEX instructions, aka WIG
>>>>instructions.  The -mevexwig=1 assembler option assumes that if the
>>>>vexw field of an VEX/EVEX instruction is 0, it is a WIG instruction.
>>>>But the vexw field of some non-WIG VEX/EVEX instructions is 0 and their
>>>>VEX.W/EVEX.W bit is determined by the integer register operand size.  This
>>>>patch set adds VEXWIG, defined as 3, to indicate that the VEX.W/EVEX.W
>>>>bit is ignored and set VexW=3 on VEX/EVEX WIG instructions.
>>>>
>>>>H.J. Lu (2):
>>>>x86: Support VEX/EVEX WIG encoding
>>>>x86: Check non-WIG EVEX instruction encoding with -mevexwig=1
>>>
>>> Furthermore you don't seem to correct/adjust here what you've done in commit
>>> 41d1ab6a6, despite me having said so right in reply to that earlier change. I
>>> continue to think that it would have been best to revert that commit (but not its
>>> amendment), adding VexWIG here as appropriate, but at the same time not
>>> corrupting cases where the field should indeed remain to be zero, i.e. when
>>> VEX.W is supposed to be determined from integer register width (i.e. REX.W).
>>
>> Please take a look at users/hjl/wig branch and tell me which one needs to
>> fix with a testcase.
>
> I'm afraid I don't understand your request. I've already answered the
> "which ones need to be fixed" part: Said commit should simply be
> reverted; only the add-on commit 5be12fc1ad should stay (by these
> get converted to VexWIG now anyway). And I can't make sense of the
> "with a testcase" part - it's mainly up to you if and where you think a
> testcase is needed (because I think existing ones already cover this).
>

Are there any specific issues on users/hjl/wig branch? If yes, please show
me a testcas which isn't handled properly.


-- 
H.J.