A small comparison

[jerro]

> void main() {
>     import std.stdio, std.algorithm, std.range;
>     enum n = 100;
>     immutable double r = n.iota.map!(x => x.sin ^^ 
> 2).reduce!q{a + b};
>     r.writeln;
> }

If I use core.stdc.math.sin and compile the code with:

gdc c.d -o c -O3 -fno-bounds-check -frelease

I get:

   404e80:	cvtsi2sd %ebx,%xmm0
   404e84:	callq  403070 <sin at plt>
   404e89:	mulsd  %xmm0,%xmm0
   404e8d:	add    $0x1,%ebx
   404e90:	cmp    $0x64,%ebx
   404e93:	addsd  0x28(%rsp),%xmm0
   404e99:	movsd  %xmm0,0x28(%rsp)
   404e9f:	jne    404e80 <_Dmain+0x60>

This is almost exactly the same code as

> .L3:
>     cvtsi2sd    %ebx, %xmm0
>     call    sin
> .L2:
>     mulsd   %xmm0, %xmm0
>     addl    $1, %ebx
>     cmpl    $100, %ebx
>     addsd   8(%rsp), %xmm0
>     movsd   %xmm0, 8(%rsp)
>     jne .L3