From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-383022-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 12862 invoked by alias); 9 Feb 2012 16:44:53 -0000
Received: (qmail 12793 invoked by uid 22791); 9 Feb 2012 16:44:52 -0000
X-SWARE-Spam-Status: No, hits=-2.9 required=5.0	tests=ALL_TRUSTED,AWL,BAYES_00
X-Spam-Check-By: sourceware.org
Received: from localhost (HELO gcc.gnu.org) (127.0.0.1)    by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 09 Feb 2012 16:44:39 +0000
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/51752] trans-mem: publication safety violated
Date: Thu, 09 Feb 2012 16:44:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: middle-end
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenth at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: aldyh at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 4.8.0
X-Bugzilla-Changed-Fields:
Message-ID: <bug-51752-4-uJixf5Q61g@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-51752-4@http.gcc.gnu.org/bugzilla/>
References: <bug-51752-4@http.gcc.gnu.org/bugzilla/>
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
Content-Type: text/plain; charset="UTF-8"
MIME-Version: 1.0
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
X-SW-Source: 2012-02/txt/msg00956.txt.bz2

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51752

--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-02-09 16:43:40 UTC ---
But isn't with

  __transaction_atomic
    {
      for (i = 0; i < 10; i++)
        if (x[i])
          x[i] += data;
    }

and

  __transaction_atomic { x[9] = 1; }

occuring concurrently the loop transaction terminated?  Thus,

  __transaction_atomic
    {
      tem = data;
      for (i = 0; i < 10; i++)
        if (x[i])
          x[i] += tem;
    }

equivalent?  We don't hoist out of the transaction region (well, as far
as I can see - the transaction region seems to be specified in a very
weak way, without virtual operands or any IL barrier or such).

<bb 2>:
  # .MEM_2 = VDEF <.MEM_1(D)>
  data = 23;
  __transaction_atomic  // SUBCODE=[ GTMA_HAVE_STORE ]

<bb 3>:
  # .MEM_3 = VDEF <.MEM_2>
  x[9] = 1;
  # .MEM_4 = VDEF <.MEM_3>
  __builtin__ITM_commitTransaction ();

<bb 4>:
  # VUSE <.MEM_4>
  return;

the __transaction_atomic  // SUBCODE=[ GTMA_HAVE_STORE ] statement
looks like an overly optimistic way to start a transaction in my quick view.