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Re: [RFC PATCH, i386]: Rewrite pop patterns to use POST_INC memory operands
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Richard Henderson <rth at redhat dot com>
- Cc: Uros Bizjak <ubizjak at gmail dot com>, gcc-patches at gcc dot gnu dot org, jh at suse dot cz
- Date: Mon, 30 Aug 2010 19:47:59 +0200
- Subject: Re: [RFC PATCH, i386]: Rewrite pop patterns to use POST_INC memory operands
- References: <AANLkTikEQw1gdzwC8DFSwp4MWJ1L_OUu68bpf6UT4cM8@mail.gmail.com> <4C7BED0E.firstname.lastname@example.org>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Mon, Aug 30, 2010 at 10:40:30AM -0700, Richard Henderson wrote:
> On 08/30/2010 10:15 AM, Uros Bizjak wrote:
> > I will wait for eventual comments due to scary %%% comment (this is
> > also why the patch is in the RFC state ATM).
> I'm sure I'm not aware of all the dataflow changes in the past years,
> so I have no real constructive feedback as to whether it should be
> expected to work now.
I must say I'm very surprised if the patch works reliably, there are many
#ifdef AUTO_INC_DEC guarded hunks and not all of them are related only
to automatic inc/dec additions, but just whether the code should look for
PRE/POST_INC/DEC/MODIFY in the IL. E.g. cleanup_auto_inc_dec
in the combiner.c to give some example.
And, cselib does very poor job with inc/dec addressing currently (except for
var-tracking which removes inc/dec addressing from the IL before feeding it