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Re: [PATCH] x86: allow suffix-less sign-extending movsb, movsw, and movsl

On Fri, Jul 1, 2016 at 8:32 AM, Jan Beulich <> wrote:
>>>> On 01.07.16 at 17:23, <> wrote:
>> On Fri, Jul 1, 2016 at 8:19 AM, Jan Beulich <> wrote:
>>>>>> On 01.07.16 at 17:12, <> wrote:
>>>> On Fri, Jul 1, 2016 at 7:55 AM, Jan Beulich <> wrote:
>>>>>>>> On 01.07.16 at 16:24, <> wrote:
>>>>>> So in the end, I guess the movzb/movzw change is fine, but this one is
>>>>>> not. It's in inherent inconsistency related to the ability of leaving
>>>>>> away the size suffixes in combination with the chosen mnemonics, it
>>>>>> seems.
>>>>> I do not understand what inconsistency you refer to here. The
>>>>> only inconsistency I can see is that one can't omit the suffixes
>>>>> from these three instructions, unlike any others with GPR
>>>>> operands.
>>>> This mnemonic inconsistency comes from ISA and AT&T syntax.
>>>> But there are no issues now.
>>> There is - as said, I fell into the trap seeing "movzb" in source code
>>> and assuming I then could also use "movzw" or "movsb" (etc). I
>>> can certainly open a bug if that helps you re-consider.
>> It is unfortunate.  But it won't lead to wrong instructions being used.
> So since I see that rational arguments won't lead anywhere here
> - would you at least allow in the fix for the bug that this change
> uncovered (the one hunk changing tc-i386.c), even if that also
> doesn't seem to cause any issues right now?

Please open a bug report with a testcase.


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