Description of problem:
gcc optimizer option -O2 produces incorrect code

Version-Release number of selected component (if applicable):
gcc-3.2.2-5 [gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5)]

How reproducible:
Every time.

Steps to Reproduce:
1.compile and run test program with -O2 option

cat <<EOF > t.c
#include <stdio.h>
#include <string.h>
#include <ctype.h>

int main(int argc, char** argv)
{
    char *str;
    char *s;

    str = strdup("abc");
    s = str;
    printf("str is [%s], s is %c\n", str, *s);
    *s++ = toupper(*s);
    printf("str is [%s], s is %c\n", str, *s);
    free(str);
    return 0;
}
EOF
gcc -o t t.c
./t
gcc -O2 -o t t.c
./t
  
Actual results:
str is [abc], s is a
str is [Bbc], s is b

Expected results:
str is [abc], s is a
str is [Abc], s is b


Additional info: