[OT] Previously: DMD - Windows -> C# in gamedev

[Alex Rønne Petersen]

On 08-01-2012 00:06, Manu wrote:
> On 7 January 2012 20:59, bearophile <bearophileHUGS at lycos.com
> <mailto:bearophileHUGS at lycos.com>> wrote:
>
>     Manu:
>
>      > The tendency to encourage use of dynamic arrays will be a major
>     problem.
>
>     I don't know how much big that problem will be, D dynamic arrays are
>     quite handy, but I agree that static arrays need to be encouraged
>     more in D (and currently most algorithms of Phobos don't work with
>     static arrays (you need to slice them first)).
>
>
> A slice doesn't produce a GC allocation does it?
> I thought a slice was just a pointer-length pair. Should live on the
> stack/in regs?

AFAIK yes.

>
> ...so slicing static arrays shouldn't be a problem right?
>
>     Currently even this code with a stack-allocated fixed size array
>     causes a heap allocation (DMD):
>
>     void main() {
>         int[2] a = [1, 2];
>     }
>
>     ASM, optimized build:
>
>     __Dmain comdat
>         push EAX
>         push EAX
>         mov EAX,offset FLAT:_D12TypeInfo_xAi6__initZ
>         push EBX
>         push 8
>         push 2
>         push EAX
>         call near ptr __d_arrayliteralTX ; heap allocation
>         add ESP,8
>         mov EBX,EAX
>         mov dword ptr [EAX],1
>         mov ECX,EBX
>         push EBX
>         lea EDX,0Ch[ESP]
>         mov dword ptr 4[EBX],2
>         push EDX
>         call near ptr _memcpy
>         add ESP,0Ch
>         xor EAX,EAX
>         pop EBX
>         add ESP,8
>         ret
>
>
> What the hell is it allocating?
> Surely that's not necessary... that's gotta be fixable?
>
>     I have suggested to add a safer version of VLAs to avoid some
>     heap-allocated dynamic arrays:
>     http://d.puremagic.com/issues/show_bug.cgi?id=5348
>
>
> +1!!
> I'm surprised this already isn't supported!


-- 
- Alex