From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-340676-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 9109 invoked by alias); 14 Dec 2010 23:15:39 -0000
Received: (qmail 9098 invoked by uid 22791); 14 Dec 2010 23:15:38 -0000
X-SWARE-Spam-Status: No, hits=-2.8 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; Tue, 14 Dec 2010 23:15:34 +0000
From: "hubicka at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/45791] Missed devirtualization
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: hubicka at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Changed-Fields:
Message-ID: <bug-45791-4-tlExjZeCs2@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-45791-4@http.gcc.gnu.org/bugzilla/>
References: <bug-45791-4@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
Date: Tue, 14 Dec 2010 23:15:00 -0000
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: 2010-12/txt/msg01659.txt.bz2

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45791

--- Comment #9 from Jan Hubicka <hubicka at gcc dot gnu.org> 2010-12-14 23:15:16 UTC ---
OK, main() code seems to optimize out that is an imrovement. Is it optimized
away with your patch pre-IPA too? 

Derived() is also devirtualizable:

Derived::Derived() (struct Derived * const this)
{
  int (*__vtbl_ptr_type) (void) * D.2237;
  int (*__vtbl_ptr_type) (void) D.2236;
  struct Base * D.2215;

<bb 2>:
  D.2215_2 = &this_1(D)->D.2115;
  D.2215_2->_vptr.Base = &_ZTV4Base[2];
  this_1(D)->D.2115._vptr.Base = &_ZTV7Derived[2];
  D.2215_3 = &this_1(D)->D.2115;
  D.2237_9 = D.2215_3->_vptr.Base;
  D.2236_10 = MEM[(int (*__vtbl_ptr_type) (void) *)D.2237_9 + 16B];
  OBJ_TYPE_REF(D.2236_10;D.2215_3->2) (D.2215_3);

We fail to devirtualize pre-IPA.  After IPA we compile into:

<bb 2>:
  MEM[(struct Base *)this_1(D)]._vptr.Base = &_ZTV4Base[2];
  this_1(D)->D.2115._vptr.Base = &_ZTV7Derived[2];
  D.2215_3 = &this_1(D)->D.2115;
  D.2236_10 = (int (*__vtbl_ptr_type) (void)) f;

a type mismatch?