From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-203291-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 5539 invoked by alias); 24 Nov 2006 10:28:40 -0000
Received: (qmail 5522 invoked by uid 48); 24 Nov 2006 10:28:31 -0000
Date: Fri, 24 Nov 2006 10:28:00 -0000
Subject: [Bug c/29968]  New: integer division by zero with optimization
X-Bugzilla-Reason: CC
Message-ID: <bug-29968-12471@http.gcc.gnu.org/bugzilla/>
Reply-To: gcc-bugzilla@gcc.gnu.org
To: gcc-bugs@gcc.gnu.org
From: "tiamat at komi dot mts dot ru" <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: 2006-11/txt/msg02101.txt.bz2

On ultrasparc hardware Linux/Solaris gcc 4.0.2, 4.0.3, 4.1.1 and
4.1.2-prerelease have a bug:

#include <stdio.h>

int testdiv(int i, int k) {
        if (k == 0) printf("found divide by zero\n");
        return(i/k);
}

int main() {
        int i = testdiv(1,0);
        return(i);
}

When compile it without optimization the expected result is received:

$ gcc test.c && ./a.out
found divide by zero
Floating point exception

But optimization broke it:

$ gcc -O3 test.c && ./a.out
Floating point exception

This bug was found with PostgreSQL 8.1.5 on Solaris 9 sparc. Regression tests
give me result:

The differences that caused some tests to fail can be viewed in the
file `./regression.diffs'.  A copy of the test summary that you see
above is saved in the file `./regression.out'.

*** expected/errors.out       Sat Feb 12 01:15:11 2005
--- results/errors.out        Thu Nov 23 18:14:08 2006
***************
*** 300,308 ****
  select 1/0::int8;
  ERROR:  division by zero
  select 1::int2/0;
! ERROR:  division by zero
  select 1/0::int2;
! ERROR:  division by zero
  select 1::numeric/0;
  ERROR:  division by zero
  select 1/0::numeric;
--- 300,310 ----
  select 1/0::int8;
  ERROR:  division by zero
  select 1::int2/0;
! ERROR:  floating-point exception
! DETAIL:  An invalid floating-point operation was signaled. This probably
means
 an out-of-range result or an invalid operation, such as division by zero.
  select 1/0::int2;
! ERROR:  floating-point exception
! DETAIL:  An invalid floating-point operation was signaled. This probably
means
 an out-of-range result or an invalid operation, such as division by zero.
  select 1::numeric/0;
  ERROR:  division by zero
  select 1/0::numeric;

Thanks a lot!


-- 
           Summary: integer division by zero with optimization
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: tiamat at komi dot mts dot ru
 GCC build triplet: sparc-linux-gnu, sparc-sun-solaris2.9, sparc64-sun-
                    solaris2.9
  GCC host triplet: sparc-linux-gnu, sparc-sun-solaris2.9, sparc64-sun-
                    solaris2.9
GCC target triplet: sparc-linux-gnu, sparc-sun-solaris2.9, sparc64-sun-
                    solaris2.9


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29968