From: Richard Biener <rguenther@suse.de>
To: Jan Hubicka <hubicka@ucw.cz>
Cc: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>,
Jan Hubicka via Gcc-patches <gcc-patches@gcc.gnu.org>
Subject: Re: Unloop no longer looping loops in loop-ch
Date: Wed, 26 Apr 2023 12:17:05 +0000 (UTC) [thread overview]
Message-ID: <nycvar.YFH.7.77.849.2304261216481.4466@jbgna.fhfr.qr> (raw)
In-Reply-To: <ZEj9RhxSm5mVZY3w@kam.mff.cuni.cz>
On Wed, 26 Apr 2023, Jan Hubicka wrote:
> > > - if (precise)
> > > + if (precise
> > > + && get_max_loop_iterations_int (loop) == 1)
> > > + {
> > > + if (dump_file && (dump_flags & TDF_DETAILS))
> > > + fprintf (dump_file, "Loop %d no longer loops.\n", loop->num);
> >
> > but max loop iterations is 1 ...?
>
> I first check for loops with 0 iterations, push them to unlooping list
> and avoid any header copying (it is useless).
> At this patch we already did header duplication and verified that the
> maximal number of iterations will drop by 1 since there is no way loop
> can terminate except for the header tests we peeled out.
>
> So 1 would turn to 0 in the loop info update and it seems useless to do
> it.
> >
> > > + loops_to_unloop.safe_push (loop);
> > > + loops_to_unloop_nunroll.safe_push (0);
> > > + }
> > > + else if (precise)
> > > {
> > > if (dump_file && (dump_flags & TDF_DETAILS))
> > > fprintf (dump_file,
> > > @@ -688,6 +699,12 @@ ch_base::copy_headers (function *fun)
> > > BITMAP_FREE (exit_bbs);
> > > }
> > > }
> > > + if (loops_to_unloop.length())
> >
> > !loops_to_unloop.is_empty ()
> I updated that in my copy of the patch.
> >
> > > + {
> > > + bool irred_invalidated;
> > > + unloop_loops (loops_to_unloop, loops_to_unloop_nunroll, NULL, &irred_invalidated);
> > > + changed = true;
> > > + }
> > > free (bbs);
> > > free (copied_bbs);
> >
> >
> > Since we run VN on the header copies I wonder if, since you remove
> > edges, we need to run CFG cleanup before this and updating SSA form?
> > For safety we usually let CFG cleanup do the actual CFG manipulation
> > and just change cond jumps to if (0) or if (1)?
>
> I do unlooping only after the VN so I think I am safe here.
Ah OK.
The patch is OK then.
Thanks,
Richard.
prev parent reply other threads:[~2023-04-26 12:17 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-25 15:12 Jan Hubicka
2023-04-25 16:04 ` Bernhard Reutner-Fischer
2023-04-25 16:10 ` Jan Hubicka
2023-04-26 7:34 ` Richard Biener
2023-04-26 10:30 ` Jan Hubicka
2023-04-26 12:17 ` Richard Biener [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=nycvar.YFH.7.77.849.2304261216481.4466@jbgna.fhfr.qr \
--to=rguenther@suse.de \
--cc=gcc-patches@gcc.gnu.org \
--cc=hubicka@ucw.cz \
--cc=rep.dot.nop@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).