g++-4.0.3: program output is different when compiled with -O3 (did not happen with gcc-3.4.5)

[Erik]

John Love-Jensen wrote:

>Well, I suppose it is a tradeoff between correct code that works-but-is-slow
>and incorrect code that is fast-and-doesn't-work.
>  
>
The fast code works, but not with gcc-4.0, -O3 and strict aliasing. 
Since there is a fast way to do it, and it works, it is a pity that it 
can not be easily used. Especially since it is such an easy problem; to 
create an ordering functor for a 32-bit type consisting of 2 16-bit types.