public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
From: "aldyh at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/46941] [trans-mem] new/delete operator are unsafe
Date: Fri, 04 Feb 2011 18:40:00 -0000	[thread overview]
Message-ID: <bug-46941-4-J9330QUl9R@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-46941-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46941

--- Comment #12 from Aldy Hernandez <aldyh at gcc dot gnu.org> 2011-02-04 18:40:09 UTC ---
Patrick, the reason memory allocated by the C++ new operator does not get
optimized by the TM-memopt pass is not because of a missing ECF_MALLOC
attribute, but because the alias oracle in GCC considers the chunk of memory as
possibly able to escape from the current function.

That is, the following hunk of code returns true in the TM-memopt pass:

      if (ptr_deref_may_alias_global_p (x))

Apparently, since new/delete operators may be overridden by class specific
hooks, the memory must be considered escaped.

So, this is not a TM bug, but a "feature" of the alias oracle in GCC.


  parent reply	other threads:[~2011-02-04 18:40 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-14 15:40 [Bug c++/46941] New: " patrick.marlier at gmail dot com
2010-12-22 10:12 ` [Bug c++/46941] " patrick.marlier at gmail dot com
2010-12-22 13:51 ` aldyh at gcc dot gnu.org
2010-12-23 15:45 ` patrick.marlier at gmail dot com
2010-12-23 16:19 ` aldyh at gcc dot gnu.org
2010-12-23 16:28 ` patrick.marlier at gmail dot com
2011-01-12 19:43 ` aldyh at gcc dot gnu.org
2011-02-02 14:17 ` patrick.marlier at gmail dot com
2011-02-03 16:24 ` aldyh at gcc dot gnu.org
2011-02-03 16:41 ` aldyh at gcc dot gnu.org
2011-02-04 13:54 ` patrick.marlier at gmail dot com
2011-02-04 15:31 ` aldyh at gcc dot gnu.org
2011-02-04 18:40 ` aldyh at gcc dot gnu.org [this message]
2011-02-04 20:13 ` patrick.marlier at gmail dot com
2011-02-04 20:16 ` aldyh at gcc dot gnu.org
2011-02-04 20:30 ` patrick.marlier at gmail dot com

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-46941-4-J9330QUl9R@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).