[PATCH] x86: fix handling of 64-bit operand size VPCMPESTR{I,M}

Jan Beulich JBeulich@suse.com
Thu Feb 23 09:11:00 GMT 2017


>>> On 22.02.17 at 19:52, <hjl.tools@gmail.com> wrote:
> On Tue, Feb 21, 2017 at 2:40 AM, Jan Beulich <JBeulich@suse.com> wrote:
>> Just like REX.W affects operand size of the implicit rAX/rDX inputs to
>> PCMPESTR{I,M}, VEX.W does for VPCMPESTR{I,M}. For that to work,
>> build_vex_prefix() needs to not only honor internally specified REX
>> flags (converting them to their VEX equivalents), but also such
>> resulting from explicit REX* prefix uses. Also adjust
>> build_evex_prefix() for consistency.
> 
> I prefer to use the "q" suffix instead of using rex64 prefix.  It will work with
> both VPCMPESTR{I,M} and PCMPESTR{I,M}.

Hmm, I'll see about doing that, but explicit REX prefixes should be
honored anyway imo. Furthermore using a suffix would add one
more example of bending Intel syntax, which doesn't know of any
suffixes for the vast majority of instructions (including the ones
here).

Jan



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