From: Eric Botcazou <ebotcazou@adacore.com>
To: Marek Polacek <polacek@redhat.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] Don't bypass blocks with multiple latch edges (PR middle-end/54838)
Date: Wed, 28 Nov 2012 09:55:00 -0000 [thread overview]
Message-ID: <1544820.Re9E01eJrW@polaris> (raw)
In-Reply-To: <20121126142843.GH17362@redhat.com>
> We then end up with
> Redirecting fallthru edge 3->4 to 6
> JUMP-BYPASS: Proved reg 59 in jump_insn 15 equals constant (const_int 1
> [0x1]) Bypass edge from 3->4 to 6
> Redirecting fallthru edge 9->4 to 5
> JUMP-BYPASS: Proved reg 59 in jump_insn 15 equals constant (const_int 3
> [0x3]) Bypass edge from 9->4 to 5
> i.e., it is assumed that in one reg there "are" two constants, that can't
> be right, right?!
No, I don't think that's the problem. The above messages are admittedly a bit
terse, they should say:
JUMP-BYPASS: Proved reg 59 in jump_insn 15 equals constant (const_int 3 [0x3])
when BB 4 is entered from BB 9. Redirect edge 9->4 to 5.
so you can have different constants for BB 3 and BB 9. The patch to tweak the
dump messages along these lines is pre-approved.
The ICE in merge_latch_edges means that the loop structure and the CFG aren't
in sync anymore. Does the cprop pass modify the former without declaring it?
--
Eric Botcazou
next prev parent reply other threads:[~2012-11-28 9:55 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-26 14:28 Marek Polacek
2012-11-28 9:55 ` Eric Botcazou [this message]
2012-11-28 18:39 ` Marek Polacek
2012-11-29 8:34 ` Richard Biener
2012-11-29 8:57 ` Steven Bosscher
2012-11-29 9:35 ` Richard Biener
2012-11-29 15:39 ` Marek Polacek
2012-11-29 15:42 ` Marek Polacek
2012-11-29 15:51 ` Steven Bosscher
2012-11-29 16:56 ` Marek Polacek
2012-11-29 17:45 ` Eric Botcazou
2012-11-30 9:02 ` Richard Biener
2012-11-30 16:28 ` Marek Polacek
2012-11-30 22:01 ` Eric Botcazou
2012-11-30 22:33 ` Eric Botcazou
2012-12-01 16:18 ` Marek Polacek
2012-12-02 10:06 ` Eric Botcazou
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=1544820.Re9E01eJrW@polaris \
--to=ebotcazou@adacore.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=polacek@redhat.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).