Threadpools, difference between DMD and LDC

[David Nadlinger via Digitalmars-d-learn]

On Sunday, 3 August 2014 at 22:24:22 UTC, safety0ff wrote:
> On Sunday, 3 August 2014 at 19:52:42 UTC, Philippe Sigaud wrote:
>>
>> Can someone confirm the results and tell me what I'm doing 
>> wrong?
>
> LDC is likely optimizing the summation:
>
>     int sum = 0;
>     foreach(i; 0..task.goal)
>         sum += i;
>
> To something like:
>
>     int sum = cast(int)(cast(ulong)(task.goal-1)*task.goal/2);

This is correct – the LLVM optimizer indeed gets rid of the loop 
completely.

Although I'd be more than happy to be able to claim a 
thousandfold speedup over DMD on real-world applications. ;)

Cheers,
David