Does foreach on array literal allocate?

[Lionello Lunesu]

Short answer: yes, they both allocate memory.

Long answer:

_d_arrayliteralT from gc.d is used to create an array:

import std.stdio;

void main()
{
  foreach(r; [1, 2, 3])
    writefln(r);
  asm { nop; }
  int a,b,c;
  foreach(r; [a, b, c])
    writefln(r);
}

__Dmain comdat
 assume CS:__Dmain
L0:  push EBP
  mov EBP,ESP
  sub ESP,028h
  push 3
  push 2
  push 1
  push 3
  push offset FLAT:_D12TypeInfo_G3i6__initZ
  call near ptr __d_arrayliteralT
  mov -024h[EBP],EAX
  mov EAX,-024h[EBP]
  lea EAX,0Ch[EAX]
  mov -020h[EBP],EAX
  add ESP,014h
L27:  mov EAX,-024h[EBP]
  cmp EAX,-020h[EBP]
  jae L4D
  mov EAX,-024h[EBP]
  mov EAX,[EAX]
  mov -01Ch[EBP],EAX
  push dword ptr -01Ch[EBP]
  push offset FLAT:_D12TypeInfo_B1i6__initZ
  call near ptr _D3std5stdio8writeflnFYv
  add dword ptr -024h[EBP],4
  add ESP,8
  jmp short L27
L4D:  nop
  xor EAX,EAX
  mov -018h[EBP],EAX
  mov -014h[EBP],EAX
  mov -010h[EBP],EAX
  push dword ptr -010h[EBP]
  push dword ptr -014h[EBP]
  push dword ptr -018h[EBP]
  push 3
  push offset FLAT:_D12TypeInfo_G3i6__initZ
  call near ptr __d_arrayliteralT
  mov -0Ch[EBP],EAX
  mov EAX,-0Ch[EBP]
  lea EAX,0Ch[EAX]
  mov -8[EBP],EAX
  add ESP,014h
L7D:  mov EAX,-0Ch[EBP]
  cmp EAX,-8[EBP]
  jae LA3
  mov EAX,-0Ch[EBP]
  mov EAX,[EAX]
  mov -4[EBP],EAX
  push dword ptr -4[EBP]
  push offset FLAT:_D12TypeInfo_B1i6__initZ
  call near ptr _D3std5stdio8writeflnFYv
  add dword ptr -0Ch[EBP],4
  add ESP,8
  jmp short L7D
LA3:  mov ESP,EBP
  pop EBP
  ret

"Bill Baxter" <wbaxter at gmail.com> wrote in message 
news:mailman.92.1228417124.22690.digitalmars-d at puremagic.com...
> Does anyone know off the top of their head if code like this allocates
> or not with current DMD 1.x compilers?
>
> foreach(x; [1, 2, 3, 4])
> {
>     // do something non-allocating with x
> }
>
> And is the answer different if the values are only known at runtime?  Like 
> here:
>
> void a func(int a1, int a2, int a3)
> {
>   foreach(x; [a1,a2,a3]) {
>         // do something non-allocating with x
>   }
>
> }
>
> --bb