public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/78904] zero-extracts are not effective
Date: Sat, 24 Jun 2023 22:12:58 +0000 [thread overview]
Message-ID: <bug-78904-4-ButZe4dYo9@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-78904-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78904
--- Comment #18 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Roger Sayle <sayle@gcc.gnu.org>:
https://gcc.gnu.org/g:8f6c747c8638d4c3c47ba2d4c8be86909e183132
commit r14-2065-g8f6c747c8638d4c3c47ba2d4c8be86909e183132
Author: Roger Sayle <roger@nextmovesoftware.com>
Date: Sat Jun 24 23:05:25 2023 +0100
i386: Add alternate representation for {and,or,xor}b %ah,%dh.
A patch that I'm working on to improve RTL simplifications in the
middle-end results in the regression of pr78904-1b.c, due to changes in
the canonical representation of high-byte (%ah, %bh, %ch, %dh) logic.
See also PR target/78904.
This patch avoids/prevents those failures by adding support for the
alternate representation, duplicating the existing *<code>qi_ext<mode>_2
as *<code>qi_ext<mode>_3 (the new version also replacing any_or with
any_logic to provide *andqi_ext<mode>_3 in the same pattern). Removing
the original pattern isn't trivial, as it's generated by define_split,
but this can be investigated after the other pieces are approved.
The current representation of this instruction is:
(set (zero_extract:DI (reg/v:DI 87 [ aD.2763 ])
(const_int 8 [0x8])
(const_int 8 [0x8]))
(subreg:DI (xor:QI (subreg:QI (zero_extract:DI (reg:DI 94)
(const_int 8 [0x8])
(const_int 8 [0x8])) 0)
(subreg:QI (zero_extract:DI (reg/v:DI 87 [ aD.2763 ])
(const_int 8 [0x8])
(const_int 8 [0x8])) 0)) 0))
after my proposed middle-end improvement, we attempt to recognize:
(set (zero_extract:DI (reg/v:DI 87 [ aD.2763 ])
(const_int 8 [0x8])
(const_int 8 [0x8]))
(zero_extract:DI (xor:DI (reg:DI 94)
(reg/v:DI 87 [ aD.2763 ]))
(const_int 8 [0x8])
(const_int 8 [0x8])))
2023-06-24 Roger Sayle <roger@nextmovesoftware.com>
gcc/ChangeLog
* config/i386/i386.md (*<code>qi_ext<mode>_3): New define_insn.
next prev parent reply other threads:[~2023-06-24 22:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-78904-4@http.gcc.gnu.org/bugzilla/>
2023-04-19 15:04 ` cvs-commit at gcc dot gnu.org
2023-06-23 8:22 ` roger at nextmovesoftware dot com
2023-06-23 17:47 ` segher at gcc dot gnu.org
2023-06-24 22:12 ` cvs-commit at gcc dot gnu.org [this message]
2023-11-14 17:36 ` cvs-commit at gcc dot gnu.org
2023-11-15 21:22 ` cvs-commit at gcc dot gnu.org
2023-11-16 18:13 ` cvs-commit 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-78904-4-ButZe4dYo9@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).