[rfa] Update PC without side effect in displaced stepping

[Mark Kettenis]

> Date: Thu, 23 Dec 2010 08:22:36 +0400
> From: Joel Brobecker <brobecker@adacore.com>
> 
> > When writing the new patch, I re-consider this problem again.  GDB
> > doesn't support displaced stepping on sparc and hppa, so it is not
> > harmful to sparc and hppa when regcache_write_pc is replaced by
> > regcache_cooked_write_unsigned.
> > Currently, GDB supports displaced stepping on s390, rs6000 (including
> > ppc-linux, aix), i386, amd64 and arm.  AFAICS, this replacement in my
> > original patch is not harmful to these targets.
> [...]
> > Given my original patch is clean, and not harmful to existing targets
> > support displaced stepping, please consider my original patch again.
> > Comments on promising directions/approaches are welcome.
> 
> I haven't seen the patch, so I cannot comment specifically, but I think
> that you are using the wrong reasons to try to justify your initial
> patch.  It does not matter whether sparc or hppa support displaced
> stepping or not. They might - it's not far-fetched for sparc, for
> instance.  Or other platforms where it matters might be contributed
> in the future, and they could need displaced stepping too.  By letting
> your patch in, we would be making it harder for other platforms to
> implement it.  It would feel like sweeping the dust under the carpet...

I have the same feeling.