Re: [rfc] Target-described register support for MIPS

Thiemo Seufer
2007-06-13T15:05:09Z

Maciej W. Rozycki wrote:
> On Tue, 12 Jun 2007, Daniel Jacobowitz wrote:
>
> > > Hmm, these look wrong -- no "ta" registers have been defined for old
> > > ABIs.
> >
> > OK, I'll drop them. They came from O32_SYMBOLIC_REGISTER_NAMES in
> > gas/config/tc-mips.c.
>
> Hmm, it looks like they may have been defined so that some weird
> handcoded assembly works for both o32 and n32 by using $t0-$t3 and
> $ta0-$ta3 -- note how the definitions are swapped for the two ABIs.
>
> But the names make no sense for o32 -- "ta" stands for
> "temporary/argument" and these are obviously not argument registers. I do
> not recall seeing any code using these names anyway and portable code will
> probably refer to the registers by numbers as $4-$15 (once you have
> recorded or discarded the arguments you are free to use all of these
> registers as temporaries anyway), possibly hiding them under some
> preprocessor macros. And GCC does not care.

The "ta" aliases are supposed to help with writing multi-ABI assembler
code, and are occasionally used for that purpose. I don't think they
are useful for disassembling. When gdb knows the ABI it should IMHO
display the "real" names instead of the "ta" aliases.

Thiemo