Re: [patch, ia64] Fix unaligned accesses on IA64 from dwarf2out.c

[Steve Ellcey <sje at cup dot hp dot com>]

On Tue, 2011-08-09 at 08:25 -0700, Richard Henderson wrote:
> On 08/08/2011 03:22 PM, Steve Ellcey wrote:
> > Oh, so after I declare md5, I call md5_finish_ctx like: 
> > 
> > 	md5_finish_ctx (&md5.ctx, md5.checksum);
> > 
> > Is that what you are proposing?  It seems a bit odd to put checksum in a
> > a structure with ctx just to guarantee its alignment and not to pass
> > them around as one entity, but I guess it's no worse then using a union.
> 
> Yes, that's what I'm proposing.
> 
> 
> r~

I think I like using a union to ensure the alignment of checksum better.
In dwarf2out.c we are always using one md5_ctx structure and one
checksum buffer but in fold-const.c there are routines where we use one
md5_ctx structure with 4 (fold_build2_stat_loc) or 6
(fold_build3_stat_loc) different checksum buffers.

If I use a structure containing one md5_ctx struct and one checksum
array then I need to create a lot of extra md5_ctx structures in
fold-const.c.  If I use the md5_ctx as it currently is and just change
checksum from a structure to a union in order to guarantee its alignment
then I don't need to increase the space the fold-const routines are
using.

Steve Ellcey
sje@cup.hp.com