I found a different behavior, with or without optimization, that I can't explain me.
In the code snippet below, the value b is 0 if you compile without optimization and 1 with optimization enabled (-O1) (gcc ver 12.3.rev1).
The only apparent difference is having defined zzz3 as volatile.
I obtained this behavior on both F3 and F4 microprocessors. The same code instead works correctly on other architectures both arm and x86, so the result is 0 both for a and b.
Is it a wrong behavior or is it part of an unpredictable behavior that can be overcome by forcing memory barrier or something else?
{
static long zzz;
static long zzz2;
static volatile long zzz3;
static int a, b;
zzz = 0x80000000-10;
zzz2 = zzz + 1000;
zzz3 = zzz2;
a = (zzz - zzz2) > (-1L);
b = (zzz - zzz3) > (-1L);
printf("1=failed : a=%d b=%d\n", a, b);
}
thanks, for help
