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

darkstalker:

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

Congratulations, it's another compiler bug.

On Windows 32 bit this code behaves in another way, it doesn't crash:

import std.stdio;
void main() {
    for (idouble j = -2i; j <= 2i; j += 0.125i) {
        for (double r = -2; r <= 2; r += 0.0625) {
            cdouble c = r + j;
            writeln(c.re, " ", c.im);
        }
    }
}


Without -O:
-2 -2
-1.9375 -2
-1.875 -2
-1.8125 -2
-1.75 -2
...
1.75 2
1.8125 2
1.875 2
1.9375 2
2 2


With -O:
-0 -9.88131e-324
-0 -9.88131e-324
-0 -9.88131e-324
-0 -9.88131e-324
-0 -9.88131e-324
-0 -9.88131e-324
-0 -9.88131e-324
...

Bye,
bearophile

On 3/31/2012 4:35 PM, darkstalker wrote:
> ---
> $ dmd -O program.d
> Internal error: backend/gloop.c 3400
> ---
>
> Is this a bug? or something wrong in my code?

Any internal error messages are compiler bugs. Please add it to bugzilla:

http://d.puremagic.com/issues/enter_bug.cgi?product=D

On Saturday, 31 March 2012 at 23:35:41 UTC, darkstalker wrote:

And I have already seen the image in that gravatar somewhere.

Bye,
bearophile