Re: [RFA] ppc/rs6000: use gdbarch_ps_regnum

["Michael Snyder" <msnyder@redhat.com>]

> On Fri, 15 Oct 2004 17:41:10 -0700
> Michael Snyder <msnyder@redhat.com> wrote:
>
>> I just happened to notice this.  Gdbarch implements PS_REGNUM,
>> so there's no reason to keep it privately in the tdep struct.
>
> Is there some good reason to move it out of the private tdep
> struct and into the public eye?
>
> I'll note that ppc_fp0_regnum is also in the tdep struct, and
> something comparable (FP0_REGNUM) is also in the gdbarch name space.
> Yet, rs6000-tdep does not set FP0_REGNUM via set_gdbarch_fp0_regnum()
> and I happen to like it this way.  The reason is that there's no good
> reason (that I know of) for the other parts of GDB to be aware of this
> register numbering.  Also, putting the indexes into the tdep struct
> gives a uniform mechanism of accessing (most of) the PPC related
> register numbers.  If we were to move either the PS or FP0 register
> number back out to gdbarch, then we'd be accessing some of the
> registers via one mechanism and these others via another.
> (Unfortunately, we still have SP_REGNUM and PC_REGNUM in gdbarch land.
> But there are good reasons for other, non-ppc specific portions to
> know about these register numbers.)

No special reason -- I just figured that if there was a public interface,
there might be some motivation to use that instead of a private interface.

PS_REGNUM is referred to quite a lot -- but mostly in other tdep and nat
files that are orthogonal to this one.  The major exception being 
std-regs.c,
which sort-of groups PS in there with PC, SP and (cover your ears, Andrew)
FP.

I have no attachment to it, though, if you prefer it the way it is.