problem compiling with optimizations enabled

[darkstalker]

I have the following source:

---
import std.stdio;

string ascii = " .:;+=xX$&";

void main()
{
    for (idouble i = -2i; i <= 2i; i += .125i)
    {
        for (double r = -2; r <= 2; r += .0625)
        {
            auto c = r + i;
            auto z = 0 + 0i;
            int iter;
            do
            {
                z = z * z + c;
                if (z.re * z.re + z.im * z.im > 4)
                    break;
                ++iter;
            } while (iter < ascii.length - 1);
            write(ascii[iter]);
        }
        writeln();
    }
}
---

It compiles and works normally, unless i turn in optimizations:

---
$ dmd -O program.d
Internal error: backend/gloop.c 3400
---

Is this a bug? or something wrong in my code?

compiler: DMD64 D Compiler v2.058 (64 bit)
OS: gentoo linux x86_64