public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/102391] Failure to optimize adjacent 8-bit loads into a single bigger load
Date: Mon, 20 Sep 2021 08:42:58 +0000	[thread overview]
Message-ID: <bug-102391-4-seTMHP0lD9@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-102391-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102391

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
the bswap pass is in principle able to handle these but it sees

  _1 = (sizetype) offset_12(D);
  _2 = RomHeader_13(D) + _1;
  _3 = *_2;
  _4 = (signed short) _3;
  _5 = _1 + 1;
  _6 = RomHeader_13(D) + _5;
  _7 = *_6;

so the constant offset is not forwarded to the MEM_REFs (int vs. size_t issue)
and the bswap pass doesn't perform any fancy dataref analysis to spot
constant offsetted same bases (it could simply use split_constant_offset
on the found base I guess or invoke DR analysis in BB mode).

  parent reply	other threads:[~2021-09-20  8:42 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-17 22:32 [Bug tree-optimization/102391] New: Failure to optimize 2 8-bit loads into a single 16-bit load gabravier at gmail dot com
2021-09-18  0:03 ` [Bug tree-optimization/102391] Failure to optimize adjacent 8-bit loads into a single bigger load gabravier at gmail dot com
2021-09-18  0:14 ` pinskia at gcc dot gnu.org
2021-09-20  8:42 ` rguenth at gcc dot gnu.org [this message]
2021-12-15 23:31 ` pinskia 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-102391-4-seTMHP0lD9@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).