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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/54735] [4.8 Regression] Segmentation fault in walk_aliased_vdefs_1
Date: Tue, 02 Oct 2012 13:03:00 -0000	[thread overview]
Message-ID: <bug-54735-4-qXjxgNMpRj@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-54735-4@http.gcc.gnu.org/bugzilla/>


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54735

--- Comment #12 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-10-02 13:03:07 UTC ---
Actually that just papers over the real issue.  The issue is that
cfg-cleanup runs before update-ssa and that removes a basic-block (9)
because we have

<bb 8>:
D.2778 ={v} {CLOBBER};
if (1 == 0)
  goto <bb 9>;
else
  goto <bb 33>;

  <bb 9>:
  # .MEM_62 = VDEF <.MEM_60>
  D.2632.m_col = 0;

  <bb 10>:
  # VUSE <.MEM_62>
  __assert_fail (0);

but as you can see this removes the definition for .MEM_62!

That is what confuses update-SSA (rightfully so - it re-assigns .MEM_62
to the inserted PHI node).

Which means we need to update virtual SSA form right here, before
calling cfgcleanup.


  parent reply	other threads:[~2012-10-02 13:03 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-28 12:54 [Bug tree-optimization/54735] New: " markus at trippelsdorf dot de
2012-09-28 13:08 ` [Bug tree-optimization/54735] " rguenth at gcc dot gnu.org
2012-09-28 19:30 ` markus at trippelsdorf dot de
2012-09-28 20:51 ` dehao at google dot com
2012-09-28 20:55 ` markus at trippelsdorf dot de
2012-09-29  7:06 ` markus at trippelsdorf dot de
2012-10-01 11:05 ` rguenth at gcc dot gnu.org
2012-10-01 15:31 ` markus at trippelsdorf dot de
2012-10-02 10:37 ` rguenth at gcc dot gnu.org
2012-10-02 11:17 ` rguenth at gcc dot gnu.org
2012-10-02 11:59 ` jamborm at gcc dot gnu.org
2012-10-02 12:08 ` markus at trippelsdorf dot de
2012-10-02 13:03 ` rguenth at gcc dot gnu.org [this message]
2012-10-04 11:48 ` rguenth at gcc dot gnu.org
2012-10-04 11:49 ` [Bug tree-optimization/54735] [4.7 " rguenth at gcc dot gnu.org
2012-11-26 14:26 ` rguenth at gcc dot gnu.org
2012-11-26 14:27 ` rguenth at gcc dot gnu.org

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