public inbox for gcc-prs@sourceware.org help / color / mirror / Atom feed
From: Jim Bray <jb@as220.org> To: nobody@gcc.gnu.org Cc: gcc-prs@gcc.gnu.org, Subject: Re: optimization/8412: Code generation problem with -march=k6 Date: Tue, 28 Jan 2003 07:06:00 -0000 [thread overview] Message-ID: <20030128070600.21090.qmail@sources.redhat.com> (raw) The following reply was made to PR optimization/8412; it has been noted by GNATS. From: Jim Bray <jb@as220.org> To: gcc-gnats@gcc.gnu.org, gcc-bugs@gcc.gnu.org, nobody@gcc.gnu.org, gcc-prs@gcc.gnu.org, alexander.puchmayr@jku.at Cc: Subject: Re: optimization/8412: Code generation problem with -march=k6 Date: 28 Jan 2003 01:59:40 -0500 I think I'm seeing this same bug, with gcc version 3.2.1 20021207 (Gentoo Linux 3.2.1-20021207) I've noticed considerable instability with multimedia things including xine, and have been studying an easily reproducible problem with xmms. I'd assumed it was 3dnow related, but testing has zeroed me in on a combination of -funroll-all-loops and -O[23]. Here are my crude notes to date. Not yet a good bug-report, The test is compiling and running xmms and doing a particular operation with it. My system is a k6-2. -finline-functions is used in all tests. CFLAGS='-march=k6-2 -g -O1' works. CFLAGS='-march=k6-2 -g -O1 -ffast-math' works. CFLAGS='-march=k6-2 -g -O1 -ffast-math -funroll-all-loops' works. CFLAGS='-march=k6-2 -g -O2 -ffast-math -funroll-all-loops' FAILS. CFLAGS='-march=k6-2 -g -O2 -ffast-math' works. CFLAGS='-march=k6-2 -O2 -ffast-math' works. The xmms configuration normally uses -funroll-all-loops, and I was seeing consistent failure with any variant of -m{cpu,arch}= {k6,k6-2} -O[23], which is not reflected above. The problem went away when the k6-specific flags were removed. I did not start getting any k6-specific build successes until I started dropping below -O2 and -funroll-all-loops. I did some studying of this with gdb, which seemed to be zeroing me into an area of code which became an unrolled loop. Bug I 'sent email to interested parties' from: http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8412 -- Jim Bray <jb@as220.org>
next reply other threads:[~2003-01-28 7:06 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2003-01-28 7:06 Jim Bray [this message] -- strict thread matches above, loose matches on Subject: below -- 2002-10-31 4:07 paolo 2002-10-31 2:56 alexander.puchmayr
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=20030128070600.21090.qmail@sources.redhat.com \ --to=jb@as220.org \ --cc=gcc-prs@gcc.gnu.org \ --cc=nobody@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: linkBe 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).