[Bug c/45262] New: Optimization results in wrong result on expression x>>31||(-x)>>31

[ylsdd at tttan dot com]

For the program below, gcc optimization produces wrong result. g++ does the
same for a cpp version of this program.
gcc 1.c -Wall
1
0
1

gcc 1.c -Wall -O
./a.out 
1
1
1

The program is as following
#include <stdio.h>

int f(unsigned int x)
{
        return x>>31||(-x)>>31;
}

int main()
{
        printf("%d\n", f(1));
        printf("%d\n", f(0));
        printf("%d\n", f(-1));
        return 0;
}


-- 
           Summary: Optimization results in wrong result on expression
                    x>>31||(-x)>>31
           Product: gcc
           Version: 4.4.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ylsdd at tttan dot com
 GCC build triplet: x86_64-linux-gnu
  GCC host triplet: x86_64-linux-gnu
GCC target triplet: x86_64-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45262