in_order_not_really.cpp

#include <iostream>
#include <vector>

#include <CL/sycl.hpp>

using namespace cl;

int main() {
  sycl::device dev{sycl::gpu_selector{}};
  sycl::queue q{dev, sycl::property_list{sycl::property::queue::in_order{}}};

  sycl::queue q1(q);
  sycl::queue q2(q);
  sycl::queue q3(q);

  std::size_t test_size = 4096;
  int *d_buf = sycl::malloc_device<int>(test_size, q);

  std::vector<int> h_buf(test_size, 0);

  for (int i = 0; i < 20; i++) {
    q1.submit([&](sycl::handler &cgh) {
      cgh.memcpy(d_buf, h_buf.data(), test_size * sizeof(int));
    });
    q2.submit([&](sycl::handler &cgh) {
      cgh.parallel_for<class Kernel>(
          sycl::range<1>{test_size}, [=](sycl::id<1> id) {
            int i = id.get(0);
            d_buf[i] = i + d_buf[(i + 1) % test_size];
            i = i * i * i;
            i = i % test_size;
            d_buf[i]++;
          });
    });
    q3.submit([&](sycl::handler &cgh) {
      cgh.memcpy(h_buf.data(), d_buf, test_size * sizeof(int));
    });
  }

  q.wait_and_throw();

  sycl::free(d_buf, q);
  return 0;
}
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