PowerPC alignment option

Joel Sherrill joel.sherrill at OARcorp.com
Sat Dec 9 17:26:31 UTC 2000

I am throwing this suggestion out for comments.
The double patch to vfprintf.c was merged in
the main newlib regardless but this is more general.

-------- Original Message --------
From: Sergei Organov <osv at javad.ru>
Subject: Re: vfprintf.c patch
To: Joel Sherrill <joel.sherrill at OARcorp.com>

Joel Sherrill <joel.sherrill at OARcorp.com> writes:


> Unfortunately, I think gcc breaks this rule on some ports.  I recall
> the HPPA using the FPU for integer multiplies.  And I recall someone
> reporting on the RTEMS list that the PowerPC would do moves of
> 8-byte structures with FP load/stores.

Joel, it was I who reported this.

I just want to let you know that it seems this behavior could be
prevented by
using -mstrict-align option to the powerpc-rtems-gcc. I now think that
probably a good idea to add this option to the gcc command line for
BSPs, as there is no real "alignment exception" handler in the BSPs that
fix unaligned accesses, so -mstrict-align should be appropriate anyway.

Sergei Organov.

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