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

[Jonas Maebe <jonas-devlists at watlock dot be>]

Jan Beulich wrote on Fri, 01 Jul 2016:

> > > > On 01.07.16 at 16:24, <jonas-devlists@watlock.be> wrote:
> > Referring again to the above document, it says about movsb/movsw:
> > "movsb is not movsb{wlq}" and "movsw
> > is not movsw{lq}" (on p. 37). Those are the only mnemonics that are
> > singled out in this way.
>
> Well, the document referenced is a random one; it's way too new
> to be a canonical reference.

I disagree that (originally) Sun documentation is a random reference  
in the context of AT&T/System V UNIX. Yes, SVR4.2 i386 documentation  
would be even better (if it mentions this issue), but I guess that  
only exists as hard copy in someone's basement.

> 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.

It is not consistent that all base mnemonics (i.e., without size  
suffix) refer to individual opcodes (or groups of opcodes) as defined  
in Intel's architecture manuals, except for movsb/w/l.


Jonas