[PATCH] Allow setting CpuVRex bit in .arch directive

[H.J. Lu]

On Tue, May 24, 2016 at 1:36 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Tue, May 24, 2016 at 12:07 PM, Jakub Jelinek <jakub@redhat.com> wrote:
>> On Tue, May 24, 2016 at 12:02:42PM -0700, H.J. Lu wrote:
>>> > Try:
>>> >         .arch corei7
>>> >         .arch .avx512f
>>> >         vpxord %xmm15, %xmm15, %xmm15
>>> >         vpxord %xmm16, %xmm16, %xmm16
>>> >
>>> > I get:
>>> > /tmp/1.s: Assembler messages:
>>> > /tmp/1.s:4: Error: bad register name `%xmm16'
>>>
>>> I opened:
>>>
>>> https://sourceware.org/bugzilla/show_bug.cgi?id=20141
>>>
>>> > and couldn't find any way how to make that assemble if I want to
>>> > disable even some ISA set and thus have to start with .arch <cpuname>
>>> > and add all the ISA sets I want to enable on top of that CPU.
>>>
>>> So you want to just disable  AVX512D, no thing else.  Wouldn't a
>>> ".noarch" directive work better?
>>
>> Well, to be able to generically disable specific ISAs (one, several).
>> An alternative to .noarch would be just allowing
>> .arch .noavx512vl etc. (like it already allows .no87).
>> Perhaps instead of mentioning all the ISAs once again with "no" prefix
>> just handle it generically, if .arch .no* is used, look first for
>> entries with explicit no at the beginning, and if not found, look for
>> the string after the prefix in the table and assume negate.
>
> Yes, it should work.

It won't work since .noavx should disable all AVX instructions,
just just AVX.  I am going to check in this patch to move all .noXXX
directives to cpu_noarch.  We can add more .noXXX to cpu_noarch.

-- 
H.J.
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