[OT] compiler optimisations

[Andrea Fontana via Digitalmars-d]

On Thursday, 23 April 2015 at 08:33:56 UTC, John Colvin wrote:
> Why can no compiler I try optimise this toy example as I would 
> expect?
>
> // uncomment if using a C compiler
> // typedef unsigned int uint;
> uint foo(uint a)
> {
>   if (a < 5)
>     return (a * 3) / 3;
>   else
>     return 0;
> }
>
> So, I would expect the compiler to be able to see that it is 
> equivalent to
>
> uint foo(uint a)
> {
>   return (a < 5) ? a : 0;
> }
>
> But apparently not a single modern compiler I tried can do this 
> optimisation, unless it's hidden in some obscure flag I'm not 
> aware of.
>
> An even more striking example can be found if you replace the / 
> with %, where the result of the function is then 
> unconditionally zero, but every compiler i tried still spat out 
> multiplication instructions.
>
> Is there a good reason for this, or is it just " * and / aren't 
> always inverses, so never mind all the cases where they are"?
>
> Now I know that this seems like a unrealistic example, but when 
> you're in complicated meta-programming situations code like 
> this can and will appear.

If I'm right, there's a website where I can see assembly 
generated by d compiler. And it's not dpaste... any hint?