public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
From: "hubicka at kam dot mff.cuni.cz" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug driver/100937] configure: Add --enable-default-semantic-interposition
Date: Mon, 22 Nov 2021 22:54:53 +0000	[thread overview]
Message-ID: <bug-100937-4-MYtAIKyTn7@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-100937-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100937

--- Comment #12 from hubicka at kam dot mff.cuni.cz ---
> (The -fno-semantic-interposition thing is probably the biggest performance gap
> between gcc -fpic and clang -fpic.)
Yep, it is often confusing to users (who do not understand what ELF
interposition is) that clang and gcc disagree on default flags here.
Recently -Ofast was extended to imply -fno-semantic-interposition that
will hopefully make more people notice this.

While doing that I have added per-symbol flag about interposition to the
symbol table, so we can also support 

__atttribute__ ((semantic_interposition))

and

__attribute__((no_semantic_interpoition))

if that would be useful for something.

      parent reply	other threads:[~2021-11-22 22:54 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-06 23:10 [Bug driver/100937] New: " i at maskray dot me
2021-06-06 23:12 ` [Bug driver/100937] " pinskia at gcc dot gnu.org
2021-06-06 23:15 ` i at maskray dot me
2021-06-06 23:19 ` pinskia at gcc dot gnu.org
2021-06-06 23:27 ` pinskia at gcc dot gnu.org
2021-06-07  8:28 ` jakub at gcc dot gnu.org
2021-06-10  5:02 ` i at maskray dot me
2021-11-02 18:16 ` frankhb1989 at gmail dot com
2021-11-03  3:19 ` egallager at gcc dot gnu.org
2021-11-03 12:25 ` redi at gcc dot gnu.org
2021-11-22 13:26 ` frankhb1989 at gmail dot com
2021-11-22 19:52 ` i at maskray dot me
2021-11-22 22:54   ` Jan Hubicka
2021-11-22 22:54 ` hubicka at kam dot mff.cuni.cz [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=bug-100937-4-MYtAIKyTn7@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).