Something went wrong when trying SYCL reduction variables with oneAPI

[JamesFBM]

Hi, I'm new to SYCL and am trying to run an example about reduction variables in the SYCL Specification. I revise the code a little and the final version is shown as follows:

#include <iostream>
#include <sycl/sycl.hpp>
#include <numeric>

using namespace sycl;

int main() {
	buffer<int> valuesBuf{ 1024 };
	{
		host_accessor a{ valuesBuf };
        // std::iota(a.begin(), a.end(), 0);
        std::iota(&(a[0]), &(a[1023]), 0);
	}

	int sumResult = 0;
	buffer<int> sumBuf{ &sumResult, 1 };
	int maxResult = 0;
	buffer<int> maxBuf{ &maxResult, 1 };

	queue myQueue;

	myQueue.submit([&](handler& cgh) {
		auto inputValues = valuesBuf.get_access<access_mode::read>(cgh);
	auto sumReduction = reduction(sumBuf, cgh, plus<>());
	auto maxReduction = reduction(maxBuf, cgh, maximum<>());

    /*
	 cgh.parallel_for(range<1> {2048, 1024}, sumReduction, maxReduction,
		[=](nd_item<1> it, auto& sum, auto& max) {
			sum += inputValues[it.get_local_id()];
			max.combine(inputValues[it.get_global_id()]);
		});
    */

    cgh.parallel_for(nd_range<1> {2048, 1024}, sumReduction, maxReduction,
		[=](nd_item<1> it, auto& sum, auto& max) {
			sum += inputValues[it.get_local_id()];
	        max.combine(inputValues[it.get_global_id()]);
		});
    });

	// assert(maxBuf.get_host_access()[0] == 1023 && sumBuf.get_host_access()[0] == 523776);
    std::cout << maxBuf.get_host_access()[0] << std::endl;
    std::cout << sumBuf.get_host_access()[0] << std::endl;
}

However, there is still something wrong with it which I cannot figure out the reasons. The problems are:

1. The code can be successfully compiled in cmd with command

   icpx -fsycl src.cpp -o o.exe​

   while when compiled in Visual Studio 2022 with Intel(R) oneAPI DPC++ Compiler, it fails and pops out the error

   SYCL kernel cannot call a variadic function
   SYCL kernel cannot call an undefined function without SYCL_EXTERNAL attribute

   I have seen a similar problem in Re: SYCL kernel cannot call an undefined function without SYCL_EXTERNAL attribute - Intel Communities  and Re: SYCL kernel cannot call an undefined function without SYCL_EXTERNAL attribute - Intel Communities and believe that Line 38 function

   max.combine(inputValues[it.get_global_id()]);​

   triggers the compilation error, but cannot find a suitable solution to my code.
2.  Even without the compilation problem above, the program cannot function as expected. For the program prints out nothing and exits with a meaningless value. The commands are shown below:

   C:\Users\a1595\Desktop\dr\c>icpx -fsycl c.cpp -o c.exe
   
   C:\Users\a1595\Desktop\dr\c>c.exe
   
   C:\Users\a1595\Desktop\dr\c>echo %ERRORLEVEL%
   -1073740791​

   A similar result also occurs in Visual Studio 2022 environment and I have no idea about it.

I am looking forward to any help. Thanks a lot.

[AishwaryaCV_Intel]

Hi,

Thank you for posting in intel communities.

Since this is a duplicate thread of <https://community.intel.com/t5/Intel-oneAPI-Data-Parallel-C/problems-about-SYCL-reduction-variables-using-oneAPI/m-p/1454057#M2774>, we will no longer monitor this thread. We will continue addressing this issue in the other thread.

Thanks And Regards,

Aishwarya