[redirect to gcc-help]
On 04/23/2010 06:25 PM, Heinz Riener wrote:
> I'm using the native GCC version[1] of my GNU/Linux distribution. I
> wonder whether GCC's optimization behavior is in the following case
> correct. Consider the following two programs:
>
> (1)
> int test(int n) {
> if (n > 0)
> return 1;
> return 0;
> }
>
> (2)
> int test(int n) {
> if (2*n > 0)
> return 1;
> return 0;
> }
>
> After compiling both with the flags '-c -O2 -pedantic -Wall', they
> result in the same object file. I expected the object files to be
> different. (The second program may overflow, the first program does
> not.)
If you have a look at the C standard, you'll see that signed integer
overflow is undefined behaviour. Therefore, it's perfectly correct to
ignore it.
Andrew.
