From: Zack Weinberg <zack@codesourcery.com>
To: martin@xemacs.org
Cc: gcc@gcc.gnu.org
Subject: Re: More embarrassing failures to optimize
Date: Sun, 05 Jan 2003 23:11:00 -0000 [thread overview]
Message-ID: <873co742mp.fsf@egil.codesourcery.com> (raw)
In-Reply-To: <15896.46933.195908.799606@wobble.local> (Martin Buchholz's message of "Sun, 5 Jan 2003 14:53:09 -0800")
Martin Buchholz <martin@xemacs.org> writes:
>>>>>> "Z" == Zack Weinberg <zack@codesourcery.com> writes:
>
> Z> I suspect this is the same underlying problem that causes
> Z> gcc.c-torture/execute/builtin-constant.c to fail. This was discussed
> Z> at some length in the thread starting at
> Z> http://gcc.gnu.org/ml/gcc-patches/2002-11/msg00235.html - it's
> Z> nontrivial to fix.
>
> Independently of whether it's related to builtin_constant_p, the fact
> that the class containing the direct conversion to bool can be
> optimized as desired suggests a different approach for improving
> optimization:
You misunderstand. The problem is a general one, having to do with
calculating common-subexpression information across basic block
boundaries. __builtin_constant_p is a convenient way to turn a
poor-optimization issue into a visible-behavior-change issue.
zw
prev parent reply other threads:[~2003-01-05 23:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-01-05 10:44 Martin Buchholz
2003-01-05 18:51 ` Zack Weinberg
2003-01-05 23:01 ` Martin Buchholz
2003-01-05 23:11 ` Zack Weinberg [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=873co742mp.fsf@egil.codesourcery.com \
--to=zack@codesourcery.com \
--cc=gcc@gcc.gnu.org \
--cc=martin@xemacs.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).