On 08-01-2012 00:06, Manu wrote:
On 7 January 2012 20:59, bearophile <bearophileh...@lycos.com
<mailto:bearophileh...@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
