Subject: re: -mstrict-align on powerpc
To: Juergen Hannken-Illjes <hannken@eis.cs.tu-bs.de>
From: matthew green <mrg@eterna.com.au>
List: tech-toolchain
Date: 03/16/2003 22:35:24
   On Sat, Mar 15, 2003 at 09:25:08PM -0800, Jason Thorpe wrote:
   > 
   > On Saturday, March 15, 2003, at 08:09  AM, Juergen Hannken-Illjes wrote:
   > 
   > >
   > >Module Name:	src
   > >Committed By:	hannken
   > >Date:		Sat Mar 15 16:09:35 UTC 2003
   > >
   > >Modified Files:
   > >	src/gnu/dist/toolchain/gcc/config/rs6000: netbsd.h
   > >
   > >Log Message:
   > >Add -mstrict-align to the CC1 default options.
   > >At least the 403 ports cannot handle unaligned access.
   > >
   > >Discussed with Jason Thorpe and Matt Thomas.
   > >
   > 
   > Hm.  Maybe what we should do is default to -mstrict-align, but disable 
   > -mstrict-align for -mcpu=foo where foo doesn't require strict alignment 
   > (e.g. 603, 604, 750, etc.).  All of those CPUs can do unaligned access 
   > on integer loads/stores, right?  Is it only the 403 that actually has 
   > the problem?  (I honestly can't remember if the 405 can do unaligned 
   > access or not...)
   
   From the sources (I have no walnut board) the 405 also traps.
   
   At least 1.6 has a shared/powerpc with X, games and text.
   Therefore the powerpc should use a feature set useable on all cpus.

that's OK;  if someone uses -m603 they are doing that themselves
and it doesn't matter ... i think jason's idea is still useful.


.mrg.