public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
From: "dann at godzilla dot ics dot uci dot edu" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/26944] [4.1/4.2 Regression] -ftree-ch generates worse code
Date: Thu, 30 Mar 2006 16:43:00 -0000 [thread overview]
Message-ID: <20060330164310.31125.qmail@sourceware.org> (raw)
In-Reply-To: <bug-26944-1008@http.gcc.gnu.org/bugzilla/>
------- Comment #2 from dann at godzilla dot ics dot uci dot edu 2006-03-30 16:43 -------
(In reply to comment #1)
> Note that this may be also PRE confusing SCEV in presence of loop headers.
Talking about PRE, here's a maybe interesting observation in the PRE dump:
<L7>:;
pretmp.30_53 = Int_Loc.0_4 * 200;
pretmp.32_23 = (int[50] *) pretmp.30_53;
pretmp.32_11 = pretmp.32_23 + Arr_2_Par_Ref_30;
goto <bb 4> (<L2>);
<L6>:;
pretmp.27_59 = Int_Loc.0_4 * 200;
pretmp.28_45 = (int[50] *) pretmp.27_59;
pretmp.28_49 = Arr_2_Par_Ref_30 + pretmp.28_45;
# Int_Index_37 = PHI <Int_Index_58(7), Int_Loc_3(5)>;
<L0>:;
D.1544_54 = pretmp.27_59;
D.1545_55 = pretmp.28_45;
D.1546_56 = pretmp.28_49;
(*D.1546_56)[Int_Index_37] = Int_Loc_3;
Int_Index_58 = Int_Index_37 + 1;
if (D.1548_41 >= Int_Index_58) goto <L8>; else goto <L9>;
<L8>:;
goto <bb 3> (<L0>);
<L9>:;
# prephitmp.33_40 = PHI <D.1546_56(8), pretmp.32_11(6)>;
# prephitmp.33_18 = PHI <D.1545_55(8), pretmp.32_23(6)>;
# prephitmp.31_25 = PHI <D.1544_54(8), pretmp.30_53(6)>;
Compare pretmp.28_49 with pretmp.32_11, why are the arguments in a different
order? Is there something unstable in the PRE algorithm?
One has to wonder what are the tree-ch effects on more complex loops.
It might be interesting test SPEC with and without tree-ch...
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26944
next prev parent reply other threads:[~2006-03-30 16:43 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-30 16:15 [Bug tree-optimization/26944] New: " dann at godzilla dot ics dot uci dot edu
2006-03-30 16:25 ` [Bug tree-optimization/26944] [4.1/4.2 Regression] " rguenth at gcc dot gnu dot org
2006-03-30 16:43 ` dann at godzilla dot ics dot uci dot edu [this message]
2006-03-31 22:41 ` Daniel Berlin
2006-03-31 22:41 ` dberlin at dberlin dot org
2006-04-02 8:12 ` pinskia at gcc dot gnu dot org
2006-04-16 19:13 ` mmitchel at gcc dot gnu dot org
2006-05-02 17:38 ` steven at gcc dot gnu dot org
2006-05-03 18:55 ` dann at godzilla dot ics dot uci dot edu
2006-05-03 19:00 ` Andrew Pinski
2006-05-03 19:00 ` pinskia at physics dot uc dot edu
2006-05-03 21:33 ` steven at gcc dot gnu dot org
2006-05-03 21:53 ` dann at godzilla dot ics dot uci dot edu
2006-05-04 21:25 ` pinskia at gcc dot gnu dot org
2006-05-25 2:39 ` mmitchel at gcc dot gnu dot org
2007-02-14 9:10 ` [Bug tree-optimization/26944] [4.1/4.2/4.3 " mmitchel at gcc dot gnu dot org
2007-06-18 5:28 ` [Bug tree-optimization/26944] [4.1/4.2 " pinskia at gcc dot gnu dot org
2008-07-04 20:22 ` [Bug tree-optimization/26944] [4.2 " jsm28 at gcc dot gnu dot org
2009-03-30 15:51 ` jsm28 at gcc dot gnu dot org
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=20060330164310.31125.qmail@sourceware.org \
--to=gcc-bugzilla@gcc.gnu.org \
--cc=gcc-bugs@gcc.gnu.org \
/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).