public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
From: "liuhongt at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/114429] [x86] (neg a) ashifrt>> 31 can be optimized to a > 0.
Date: Fri, 22 Mar 2024 06:09:27 +0000 [thread overview]
Message-ID: <bug-114429-4-S0lzTMITsI@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-114429-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114429
--- Comment #2 from Hongtao Liu <liuhongt at gcc dot gnu.org> ---
(In reply to Hongtao Liu from comment #1)
> when x is INT_MIN, I assume -x is UD, so compiler can do anything.
> otherwise, (-x) >> 31 is just x > 0.
> From rtl view. neg of INT_MIN is assumed to 0 after it's truncated.
Wait, is -INT_MIN truncated to INT_MIN? if that's case, we can't do the
optimization at rtl.
next prev parent reply other threads:[~2024-03-22 6:09 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-22 5:39 [Bug target/114429] New: " liuhongt at gcc dot gnu.org
2024-03-22 5:44 ` [Bug target/114429] " liuhongt at gcc dot gnu.org
2024-03-22 6:09 ` liuhongt at gcc dot gnu.org [this message]
2024-03-22 6:47 ` liuhongt at gcc dot gnu.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=bug-114429-4-S0lzTMITsI@http.gcc.gnu.org/bugzilla/ \
--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).