Comment 13 for bug 721531

I see a very similar issue even with -O0 when using GCC 4.5.2-8ubuntu1 on my ARM board.

Here is a simple test:
<snip>
$ cat test.c && gcc -O0 -Wall -Winline test.c -o test.bin && echo "O0:" && ./test.bin && gcc -O2 -Wall -Winline test.c -o test.bin && echo "O2:" && ./test.bin

#include <stdio.h>

static long __attribute__ ((noinline))
getfp (void *p)
{
  return (long) p;
}

static void __attribute__ ((noinline))
myfunc(long fp, long foo, long bar, long code, long thumb, long thumb2)
{
  printf ("\tfp: 0x%lx\n", fp);
  printf ("\tfoo: 0x%lx\n", foo);
  printf ("\tbar: 0x%lx\n", bar);
  printf ("\tcode: 0x%lx\n", code);
  printf ("\tthumb: 0x%lx\n", thumb);
  printf ("\tthumb2: 0x%lx\n", thumb2);
}

int main()
{
  long fp = (long) myfunc;
  long foo = fp & 0x1L;
  long bar = getfp (myfunc);
  long code = (long) myfunc & ~0x1L;
  long thumb = (long) myfunc & 0x1L;
  long thumb2 = getfp (myfunc) & 0x1L;
  myfunc(fp, foo, bar, code, thumb, thumb2);
  return 0;
}

O0:
        fp: 0x83b1
        foo: 0x1
        bar: 0x83b1
        code: 0x83b0
        thumb: 0x0
        thumb2: 0x1
O2:
        fp: 0x83a1
        foo: 0x0
        bar: 0x83a1
        code: 0x83a0
        thumb: 0x0
        thumb2: 0x1
</snip>

The interesting thing is the " (long) myfunc & 0x1L".