the following code compiled with GDC shows the bug
(I'm using the gcc 4.8 windows mingw32 version from https://bitbucket.org/goshawk/gdc/downloads)

import std.math;
import std.stdio;
import std.range;
import std.parallelism;

void main()
{
    enum n = 1000;
    float step = 1.0f/n;

    float[n] results_singlethreaded;
    float[n] results_multithreaded;

    foreach(i; iota(n))
        results_singlethreaded[i] = pow(step * i, 0.4545f);
    foreach(i; parallel(iota(n)))
        results_multithreaded[i] = pow(step * i, 0.4545f);
    foreach(i; iota(n))
        assert(results_singlethreaded[i] == results_multithreaded[i]);
}

~/Desktop $ ./test.exe
core.exception.AssertError@test.d(26): Assertion failure

The same code passes without assertion when compiled with DMD.

Am Sun, 02 Jun 2013 07:17:12 +0200
schrieb "finalpatch" <fengli@gmail.com>:

> the following code compiled with GDC shows the bug
> (I'm using the gcc 4.8 windows mingw32 version from
> https://bitbucket.org/goshawk/gdc/downloads)
> 
> import std.math;
> import std.stdio;
> import std.range;
> import std.parallelism;
> 
> void main()
> {
>      enum n = 1000;
>      float step = 1.0f/n;
> 
>      float[n] results_singlethreaded;
>      float[n] results_multithreaded;
> 
>      foreach(i; iota(n))
>          results_singlethreaded[i] = pow(step * i, 0.4545f);
>      foreach(i; parallel(iota(n)))
>          results_multithreaded[i] = pow(step * i, 0.4545f);
>      foreach(i; iota(n))
>          assert(results_singlethreaded[i] ==
> results_multithreaded[i]);
> }
> 
> ~/Desktop $ ./test.exe
> core.exception.AssertError@test.d(26): Assertion failure
> 
> The same code passes without assertion when compiled with DMD.

Please file a bug report on bugzilla.gdcproject.org

I can't reproduce this on linux/posix. Could you use feqrel to check the number of equal bits of the single/multithreaded results?

Bug reported as #58
http://bugzilla.gdcproject.org/show_bug.cgi?id=58
I have added the output from feqrel to the report.

On Sunday, 2 June 2013 at 08:28:42 UTC, Johannes Pfau wrote:
>> 
>> The same code passes without assertion when compiled with DMD.
>
> Please file a bug report on bugzilla.gdcproject.org
>
> I can't reproduce this on linux/posix. Could you use feqrel to check
> the number of equal bits of the single/multithreaded results?