Assert when calling empty restrict(amp) function in VS 11 Beta

Question

I found a case that triggers an assert using C++ AMP in VS 11 Beta. Just define an empty function like this:

    void EmptyFunction(array_view<const float, 2> someView) restrict(amp) {}

Call this function inside a parallel_for_each. If the code was compiled with the Debug config, a dialog box appears saying that a debug assertion failed. Here is the full text:

    Debug Assertion Failed!

    Program: ...ts\Visual Studio 11\Projects\CLAHE\bin\Debug\CLAHE.vshost.exe
    File: f:\dd\vctools\dpcxxrt\src\dpcrt_compiler.cpp
    Line: 519

    Expression: handle-> _M_device_buffer_info[i]._M_formal_access_mode != _Read_access || !pBufferRWProperty[i]

There is no assert when compiled with the Release config.

Edit: Change "float" to "const float" as noted by Weirong below.

Answer 1

Hi Tevo,

Thanks for reporting this.  This looks like a known bug and we should have it fixed for the final product.

I can reproduce the issue in VS11 Beta with code like:

#include <amp.h>
using namespace concurrency;

void EmptyFunction(array_view<const float, 2> someView) restrict(amp) {}

int main()
{
    float x; 
    array_view<const float, 2> av(1, 1, &x);
    parallel_for_each(av.extent, [=] (index<2> idx) restrict(amp) {
       EmptyFunction(av);
    });
    
    return 0;
}

Note my EmptyFunction is slightly different from yours. If I replace "const float" with "float", then I cannot reproduce the assertion as you have seen. So to confirm that we indeed fixed the bug you are experiencing, could you show me the small example you have (if it's not the same as mine) that can trigger the assertion?

Thanks very much,

Weirong

Answer 2

Thanks, Weirong. You are correct that my test case had "const float", not just "float".