DMD: slow coping for small static arrays.

[Ilya Yaroshenko via Digitalmars-d]

I have found that DMD can not optimise array coping for small 
static arrays:

Code:
-----------------------------------
size_t[8] foo(size_t[8] x)
{
  size_t[8] ret = void;
  ret[0..3] = x[5..8];
  ret[3..8] = x[0..5];
  return ret;
}
-----------------------------------
DMD (nightly build): http://goo.gl/CAufv8
-----------------------------------
ulong[8] example.foo(ulong[8]):
        push   rbp
        mov    rbp,rsp
        sub    rsp,0x10
        mov    QWORD PTR [rbp-0x8],rdi
        mov    edx,0x18
        lea    rsi,[rbp+0x38]
        call   1a <ulong[8] example.foo(ulong[8])+0x1a>
        mov    edx,0x28
        lea    rsi,[rbp+0x10]
        mov    rax,QWORD PTR [rbp-0x8]
        lea    rdi,[rax+0x18]
        call   30 <ulong[8] example.foo(ulong[8])+0x30>
        mov    rax,QWORD PTR [rbp-0x8]
        mov    rsp,rbp
        pop    rbp
        ret
        add    BYTE PTR [rax],al
        ...
-----------------------------------

GDC 4.2: http://goo.gl/RdcjeV
-----------------------------------
uint[8] example.foo(uint[8]):
        movl    4(%esp), %eax
        movl    28(%esp), %edx
        movl    %edx, (%eax)
        movl    32(%esp), %edx
        movl    %edx, 4(%eax)
        movl    36(%esp), %edx
        movl    %edx, 8(%eax)
        movl    8(%esp), %ecx
        movl    %ecx, 12(%eax)
        movl    12(%esp), %ecx
        movl    %ecx, 16(%eax)
        movl    16(%esp), %ecx
        movl    %ecx, 20(%eax)
        movl    20(%esp), %ecx
        movl    %ecx, 24(%eax)
        movl    24(%esp), %ecx
        movl    %ecx, 28(%eax)
        ret     $4
-----------------------------------

Fast coping is important for new N-demensional ranges 
https://github.com/D-Programming-Language/phobos/pull/3397 .

I want to know should I write a work around for DMD OR DMD would 
be fixed during this year?