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Re: Gas can't handle prefix generated by gcc


On Fri, Jul 23, 2004 at 01:53:53PM -0700, Zack Weinberg wrote:
> "H. J. Lu" <hjl@lucon.org> writes:
> 
> > On Fri, Jul 23, 2004 at 01:43:33PM -0700, Zack Weinberg wrote:
> >> "H. J. Lu" <hjl@lucon.org> writes:
> >> 
> >> > On Fri, Jul 23, 2004 at 12:49:48PM -0700, Zack Weinberg wrote:
> >> >> Zack Weinberg <zack@codesourcery.com> writes:
> >> >> 
> >> >> > "H. J. Lu" <hjl@lucon.org> writes:
> >> >> >
> >> >> >> It seems that gcc uses a prefix syntax which gas doesn't handle. Does
> >> >> >> gcc always use " ; " as prefix separator?
> >> >> >
> >> >> > Yes.  It does that for cs/ds on branch hints, it does that for "rep"
> >> >> > on string instructions, it does that for "lock" on atomic updates.
> >> >> 
> >> >> Correction - it uses either " ; " or \n\t in all the above cases.
> >> >> 
> >> >
> >> > It looks like a gcc bug to me. Assembler has a way to define prefixes
> >> > for an instruction. Unfortunately, gcc uses something else. I will
> >> > close the assembler bug.
> >> 
> >> Not so fast.  Is the PREFIX_SEPARATOR mechanism (a) supported by GAS
> >> since time immemorial, and (b) supported by all other i386 assemblers
> >> since time immemorial?  If *either* of those is not true, GCC can't
> >> change.
> >
> > It was added to gas on Jun 8, 1998.
> 
> Ok, that's good enough.  Now how about (b)?
> 

I have no ideas how other i386 assemblers handle it. It doesn't matter
much since gcc should check this feature before using it.


H.J.


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