From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-419907-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 26396 invoked by alias); 12 Apr 2013 08:45:49 -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
Received: (qmail 26360 invoked by uid 55); 12 Apr 2013 08:45:46 -0000
From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/56921] [4.9 Regression] ICE in rtx_cost called by doloop_optimize_loops for PPC
Date: Fri, 12 Apr 2013 08:45:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: rtl-optimization
X-Bugzilla-Keywords: ice-on-valid-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenther at suse dot de
X-Bugzilla-Status: NEW
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 4.9.0
X-Bugzilla-Changed-Fields:
Message-ID: <bug-56921-4-x1GpfoGAbj@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-56921-4@http.gcc.gnu.org/bugzilla/>
References: <bug-56921-4@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
X-SW-Source: 2013-04/txt/msg01052.txt.bz2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56921

--- Comment #9 from rguenther at suse dot de <rguenther at suse dot de> 2013-04-12 08:45:46 UTC ---
On Fri, 12 Apr 2013, steven at gcc dot gnu.org wrote:

> 
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56921
> 
> --- Comment #8 from Steven Bosscher <steven at gcc dot gnu.org> 2013-04-12 08:36:04 UTC ---
> (In reply to comment #7)
> > niter_desc is not marked GTY(()) but is cached from struct loop aux field.
> > niter_desc uses heap memory but points to GC memory.  Thus, caching of this
> > across passes is not safe.
> > I suppose passes are missing free_simple_loop_desc, loop-doloop.c calls
> > get_simple_loop_desc but never free_simple_loop_desc for example (which
> > then at least leaks the niter_desc memory).
> 
> Another, IMHO better, solution would be to not use loop->aux but make
> a GC-safe vec indexed by loop->num. Maybe add checking in the loop
> verifier that no struct niter_desc is left pending if its parent loop
> is removed.
> 
> That should make the loop passes GC safe.
> 
> Then mark all "aux" fields as GC unsafe and document that every pass is
> responsible for cleaning up after itself.

Yes, definitely.  I was bit once by this ->aux usage which is
not really obvious.

Richard.