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Re: [PATCH] x86: allow suffix-less sign-extending movsb, movsw, and movsl
- From: "Jan Beulich" <JBeulich at suse dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: "Binutils" <binutils at sourceware dot org>, "Jonas Maebe" <jonas-devlists at watlock dot be>
- Date: Fri, 01 Jul 2016 09:32:02 -0600
- Subject: Re: [PATCH] x86: allow suffix-less sign-extending movsb, movsw, and movsl
- Authentication-results: sourceware.org; auth=none
- References: <577655C002000078000FA593 at prv-mh dot provo dot novell dot com> <CAMe9rOodb0Grq+soDSJq4aZfneTEkmJy8_M-quUBn6FJyK_=6w at mail dot gmail dot com> <57768C3F02000078000FA6B0 at prv-mh dot provo dot novell dot com> <20160701154345 dot Horde dot cBkeSkisJlFXdnORG8cFS7A at mail dot elis dot ugent dot be> <577693C902000078000FA6FB at prv-mh dot provo dot novell dot com> <20160701162450 dot Horde dot hClcNkisJlFXdn0ysfmHqqA at mail dot elis dot ugent dot be> <5776A08802000078000FA759 at prv-mh dot provo dot novell dot com> <CAMe9rOo_XMW2i7PurLee7y_VsiucwUjrPJEjHGuhWv9G1ipE4A at mail dot gmail dot com> <5776A63202000078000FA788 at prv-mh dot provo dot novell dot com> <CAMe9rOrxXuHaZx4xo6E+rFubDfUOtyaU00zGACEz7q5Au7assA at mail dot gmail dot com>
>>> On 01.07.16 at 17:23, <hjl.tools@gmail.com> wrote:
> On Fri, Jul 1, 2016 at 8:19 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>>> On 01.07.16 at 17:12, <hjl.tools@gmail.com> wrote:
>>> On Fri, Jul 1, 2016 at 7:55 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>>>>> On 01.07.16 at 16:24, <jonas-devlists@watlock.be> 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?
Jan
- References:
- [PATCH] x86: allow suffix-less sign-extending movsb, movsw, and movsl
- Re: [PATCH] x86: allow suffix-less sign-extending movsb, movsw, and movsl
- Re: [PATCH] x86: allow suffix-less sign-extending movsb, movsw, and movsl
- Re: [PATCH] x86: allow suffix-less sign-extending movsb, movsw, and movsl
- Re: [PATCH] x86: allow suffix-less sign-extending movsb, movsw, and movsl
- Re: [PATCH] x86: allow suffix-less sign-extending movsb, movsw, and movsl
- Re: [PATCH] x86: allow suffix-less sign-extending movsb, movsw, and movsl
- Re: [PATCH] x86: allow suffix-less sign-extending movsb, movsw, and movsl
- Re: [PATCH] x86: allow suffix-less sign-extending movsb, movsw, and movsl
- Re: [PATCH] x86: allow suffix-less sign-extending movsb, movsw, and movsl