[Bug c/29968] New: integer division by zero with optimization

[tiamat at komi dot mts dot ru]

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