Re: Creating X32 ABI code with GCC?

[Vincent Diepeveen <diep@xxxxxxxxx>]

John that's not what i'm looking for -m32 creates full 32 bits  
executables says manual page here.

I'm looking for 64 bits executables with 32 bits adressing. So i want  
to use the full 64 bits functionality except when it comes
 to the array lookups. If all code gets put to 32 bits you lose the  
huge advantages of 64 bits, being more registers and for
some code doing it in 64 bits is faster than 32 bits.



On May 21, 2012, at 8:14 PM, Jonathan Wakely wrote:

> On 21 May 2012 18:55, Vincent Diepeveen wrote:
> > hi,
> >
> > Kernel 3.4 supports X32 ABI.
> >
> > see
> > http://kernelnewbies.org/ 
> > Linux_3.4#head-039c9d273884c9639937c10d68b4a3214869eb4b
> >
> > This could give fantastic speedups at x64 hardware as it combines the
> > advantages of 64 bits
> >  programming, bunch of registers, with the advantage of still  
> > reusing the
> > old codes 'signed integer' lookup
> > which right now slows down so much in x64 as it creates an extra sign
> > extension for the lookup 32 bits signed
> >  value to 64 bits signed value.
> >
> > Does GCC already support this and if so which options can i  
> > trigger this
> > with GCC?
> >
> > If so does this work at all x64 processors as well?
> >
> > If i google i see a few postings about X32 'backported to GCC'  
> > attempt in
> > 2011 somewhere, but no confirmation whatsoever.
>
> Google harder :)
>
> If I search for x32 gc the top hit is the x32 project homepage  
> which says
>
> "X32 is functional complete with C, C++, Objective C and Fortran on
> GCC trunk as of revision 177914"
>
> The manual for GCC 4.7 documents the -mx32 switch at
> http://gcc.gnu.org/onlinedocs/gcc-4.7.0/gcc/i386-and-x86_002d64- 
> Options.html

That's creating a full 32 bits executable isn't it?