[rfa] Update PC without side effect in displaced stepping

[Joel Brobecker]

> 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...

-- 
Joel