-O2 cause optimization issues while va parameters functions - linaro-toolchain

27 Apr 2011


      Hi All,
As i have frequently said, we are using 2011.3 4.5 linaro gcc. For the
following codes, if we compile it by -O2, it will crash with "segment
fault", if we just comment " if(unifi_debug >= level) {", all will be
ok.
If we don't compile it by -O2, all will be ok too.
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#define DEBUG_BUFFER_SIZE 80
int unifi_debug = 5;
void
unifi_trace(void* ospriv, int level, const char *fmt, ...)
{
        static char s[DEBUG_BUFFER_SIZE];
        va_list args;
        unsigned int len;
if(unifi_debug >= level) {
                va_start(args, fmt);
                len = vsnprintf(&(s)[0],
                    (DEBUG_BUFFER_SIZE),
                         fmt, args);
va_end(args);
                if (len >= DEBUG_BUFFER_SIZE) {
                    (s)[DEBUG_BUFFER_SIZE - 2] = '\n';
                    (s)[DEBUG_BUFFER_SIZE - 1] = 0;
                }
printf("%s", s);
        }
}
int main(void)
{
        char *prog = "/usr/sbin/unififw";
        unifi_trace(NULL, 1, "start %s\n", prog);
        return 0;
}
Thanks
Barry