SYCL named function objects compile error ( Needs keyword "const" for operator () )

Sidarth — Mon, 29 Jul 2024 18:20:48 GMT

Hello,

I am trying to compile a simple SYCL program which runs parallel for using "Named function objects" instead of lambdas. I get a compile error which ultimately is resolved if I add "const" to the end of the overloaded () operator and I am not sure why that is the case. Could someone please point out why the "const" qualifier is needed and if there are any ways around it ?

#include <iostream> #include <sycl/sycl.hpp> #define SIZE 10 #define DIV 12.3 using namespace sycl; class test_kernel { public: test_kernel(int* xx, const double yy):x(xx), y(yy) {} void operator() (nd_item<3> itm) { int idx = itm.get_global_id(0); if(idx < SIZE) x[idx] = y/12.3; } private: int* x; double y; }; int main() { queue m_que{default_selector_v}; range<3> global_range(SIZE,1,1); range<3> local_range(SIZE,1,1); std::cout << "Device Name: " << m_que.get_device().get_info<info::device::name>() << std::endl; double val = DIV * 1000; int* x = malloc_shared<int>(SIZE, m_que); for(int i =0; i<SIZE; i++) { x[i] = 10; } m_que.parallel_for(sycl::nd_range<3>{global_range,local_range}, test_kernel{x, val}).wait(); for(int i = 0; i < SIZE; i++) { if(x[i] != 1000) { std::cout << "x[ " << i << "] = " << x[i] << " instead of " << int(val/DIV) << std::endl; } } free(x, m_que); }

Here is the compile command and error:

snarayanan@crane:builds$ icpx -fsycl -o submit_to_gpu_complex ../src/submit_to_gpu_complex.cpp In file included from ../src/submit_to_gpu_complex.cpp:2: In file included from /usr/people/shared/tools/rocky/9/intel_oneapi/2024.1.0/compiler/2024.1/bin/compiler/../../include/sycl/sycl.hpp:16: In file included from /usr/people/shared/tools/rocky/9/intel_oneapi/2024.1.0/compiler/2024.1/bin/compiler/../../include/sycl/backend.hpp:27: /usr/people/shared/tools/rocky/9/intel_oneapi/2024.1.0/compiler/2024.1/bin/compiler/../../include/sycl/handler.hpp:1540:5: error: no matching function for call to object of type 'const test_kernel' 1540 | KernelFunc(detail::Builder::getElement(detail::declptr<ElementType>())); | ^~~~~~~~~~ /usr/people/shared/tools/rocky/9/intel_oneapi/2024.1.0/compiler/2024.1/bin/compiler/../../include/sycl/handler.hpp:1617:10: note: in instantiation of function template specialization 'sycl::handler::kernel_parallel_for<test_kernel, sycl::nd_item<3>, test_kernel>' requested here 1617 | h->kernel_parallel_for<TypesToForward..., Props...>(Args...); | ^ /usr/people/shared/tools/rocky/9/intel_oneapi/2024.1.0/compiler/2024.1/bin/compiler/../../include/sycl/handler.hpp:1703:29: note: in instantiation of function template specialization 'sycl::handler::KernelPropertiesUnpackerImpl<>::kernel_parallel_for_unpack<test_kernel, sycl::nd_item<3>, test_kernel, test_kernel>' requested here 1703 | Unpacker.template kernel_parallel_for_unpack<KernelName, ElementType, | ^ /usr/people/shared/tools/rocky/9/intel_oneapi/2024.1.0/compiler/2024.1/bin/compiler/../../include/sycl/handler.hpp:1699:5: note: in instantiation of function template specialization 'sycl::handler::unpack<test_kernel, test_kernel, sycl::ext::oneapi::experimental::properties<std::tuple<>>, false, (lambda at /usr/people/shared/tools/rocky/9/intel_oneapi/2024.1.0/compiler/2024.1/bin/compiler/../../include/sycl/handler.hpp:1702:21)>' requested here 1699 | unpack<KernelName, KernelType, PropertiesT, | ^ /usr/people/shared/tools/rocky/9/intel_oneapi/2024.1.0/compiler/2024.1/bin/compiler/../../include/sycl/handler.hpp:1373:5: note: in instantiation of function template specialization 'sycl::handler::kernel_parallel_for_wrapper<test_kernel, sycl::nd_item<3>, test_kernel, sycl::ext::oneapi::experimental::properties<std::tuple<>>>' requested here 1373 | kernel_parallel_for_wrapper<NameT, TransformedArgType, KernelType, | ^ /usr/people/shared/tools/rocky/9/intel_oneapi/2024.1.0/compiler/2024.1/bin/compiler/../../include/sycl/handler.hpp:2370:5: note: in instantiation of function template specialization 'sycl::handler::parallel_for_impl<sycl::detail::auto_name, test_kernel, 3, sycl::ext::oneapi::experimental::properties<std::tuple<>>>' requested here 2370 | parallel_for_impl<KernelName>(Range, Properties, std::move(KernelFunc)); | ^ /usr/people/shared/tools/rocky/9/intel_oneapi/2024.1.0/compiler/2024.1/bin/compiler/../../include/sycl/queue.hpp:2504:24: note: in instantiation of function template specialization 'sycl::handler::parallel_for<sycl::detail::auto_name, test_kernel, sycl::ext::oneapi::experimental::properties<std::tuple<>>, 3>' requested here 2504 | CGH.template parallel_for<KernelName>(Range, Properties, Rest...); | ^ /usr/people/shared/tools/rocky/9/intel_oneapi/2024.1.0/compiler/2024.1/bin/compiler/../../include/sycl/queue.hpp:2519:12: note: in instantiation of function template specialization 'sycl::queue::parallel_for<sycl::detail::auto_name, 3, sycl::ext::oneapi::experimental::properties<std::tuple<>>, test_kernel &>' requested here 2519 | return parallel_for<KernelName>( | ^ ../src/submit_to_gpu_complex.cpp:43:11: note: in instantiation of function template specialization 'sycl::queue::parallel_for<sycl::detail::auto_name, 3, test_kernel>' requested here 43 | m_que.parallel_for(sycl::nd_range<3>{global_range,local_range}, test_kernel{x, val}).wait(); | ^ ../src/submit_to_gpu_complex.cpp:15:9: note: candidate function not viable: 'this' argument has type 'const test_kernel', but method is not marked const 15 | void operator() (nd_item<3> itm) | ^ 1 error generated.

DPC++ compiler version:

snarayanan@crane:builds$ icpx --version Intel(R) oneAPI DPC++/C++ Compiler 2024.1.0 (2024.1.0.20240308) Target: x86_64-unknown-linux-gnu Thread model: posix InstalledDir: /usr/people/shared/tools/rocky/9/intel_oneapi/2024.1.0/compiler/2024.1/bin/compiler Configuration file: /usr/people/shared/tools/rocky/9/intel_oneapi/2024.1.0/compiler/2024.1/bin/compiler/../icpx.cfg

Re: SYCL named function objects compile error ( Needs keyword "const" for operator () )

Alex_Y_Intel — Tue, 30 Jul 2024 19:39:01 GMT

I'm escalating your question to our internal team for further investigation.

topic SYCL named function objects compile error ( Needs keyword "const" for operator () ) in Intel® oneAPI DPC++/C++ Compiler

SYCL named function objects compile error ( Needs keyword "const" for operator () )

Re: SYCL named function objects compile error ( Needs keyword "const" for operator () )