From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-204025-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 29186 invoked by alias); 2 Dec 2006 17:46:54 -0000
Received: (qmail 29150 invoked by uid 48); 2 Dec 2006 17:46:45 -0000
Date: Sat, 02 Dec 2006 17:46:00 -0000
Message-ID: <20061202174645.29149.qmail@sourceware.org>
X-Bugzilla-Reason: CC
References: <bug-28752-12180@http.gcc.gnu.org/bugzilla/>
Subject: [Bug middle-end/28752] bootstrap comparision fails with "-ftree-vectorize -maltivec" on ppc and i386
In-Reply-To: <bug-28752-12180@http.gcc.gnu.org/bugzilla/>
Reply-To: gcc-bugzilla@gcc.gnu.org
To: gcc-bugs@gcc.gnu.org
From: "volodyan at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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: 2006-12/txt/msg00210.txt.bz2



------- Comment #28 from volodyan at gmail dot com  2006-12-02 17:46 -------
(In reply to comment #27)
> I committed the patch that enables vectorization of strided accesses


Confirmed the bug on gcc-4.3/(Pentium-M)X86. Configured  as 
../gcc/configure   --enable-bootstrap --enable-languages=c
and built as
make BOOT_CFLAGS="-g   -msse2 -ftree-vectorize -O2" 

Bootstrap failed after wrong execution of the following loop from
cfgloopanal.c/dfs:

  printf("nvert= %d, nq in dfs=%d, post0=%d\n",g->n_vertices, nq, 
g->vertices[0].post);

  for (i = 0; i < g->n_vertices; i++)
    {
      g->vertices[i].component = -1;
      g->vertices[i].post = -1;
    }
 printf("post0=%d; i in dfs=%d\n", g->vertices[0].post, i);
[printf's added by me]

It appears that this loop, which is vectorized according to the vectorizer
dump, doesn't manage to initialize g->vertices[i].post = -1 - the second printf
outputs 0 instead of expected -1 leading to dfs falsely assuming that this
vertex is new and crashing later:

nvert= 10, nq in dfs=8, post0=0
post0=0; i in dfs=10
../../gcc/gcc/crtstuff.c: In function ‘__do_global_dtors_aux’:
../../gcc/gcc/crtstuff.c:265: internal compiler error: Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://gcc.gnu.org/bugs.html> for instructions.
make[3]: *** [crtbegin.o] Error 1
make[3]: Leaving directory `/Develop/mainline/build/gcc'
make[2]: *** [all-stage2-gcc] Error 2
make[2]: Leaving directory `/Develop/mainline/build'
make[1]: *** [stage2-bubble] Error 2
make[1]: Leaving directory `/Develop/mainline/build'
make: *** [all] Error 2
lnx-toshiba:/Develop/mainline/build #


Vladimir 


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28752