This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [PATCH] Fix s390 fallout from PR11271 patch
- From: Richard Earnshaw <rearnsha at arm dot com>
- To: Eric Botcazou <ebotcazou at libertysurf dot fr>
- Cc: Richard Earnshaw <rearnsha at arm dot com>, Ulrich Weigand <weigand at i1 dot informatik dot uni-erlangen dot de>, gcc-patches at gcc dot gnu dot org
- Date: Tue, 02 Dec 2003 13:52:47 +0000
- Subject: Re: [PATCH] Fix s390 fallout from PR11271 patch
- Organization: ARM Ltd.
- Reply-to: Richard dot Earnshaw at arm dot com
> > If this code were to be enabled for the thumb case, I think we'd end up
> > with invalid output. The reason being that the code would attempt to
> > generate a sum of the stack pointer and another register, but that's
> > invalid: one of the reasons the stack pointer isn't classed as a base
> > register is because this mode of addressing is not supported for stack
> > accesses.
>
> Okay. But the comment is very misleading.
The code was almost certainly written before thumb support was added. It
just so happens that things work correctly with that code not matching
(for an over-sized stack offset); but I think it would break if it were
changed as you suggested.
I'm sure that most ports are largely written by doing a basic port and
then fixing things that don't quite work right. I know that's how the
Thumb support was added. I very much doubt that every line of source in
the compiler is analysed by each engineer adding a new back end.
R.