rocm-systems/samples/0_Intro/hcc_dialects/vadd_hc_am.cpp

// Simple test showing how to use HC syntax with AM (accelerator memory).
// AM provides a set of c-style memory management routines for allocating,
// freeing, and copying memory.   am_alloc returns a device pointer
// which can only be used on the device.  The programmer has full control
// over when data is copied.  

#include <hc.hpp>
#include <hc_am.hpp>

int main(int argc, char *argv[])
{
    int sizeElements = 1000000;
    size_t sizeBytes = sizeElements * sizeof(float);
    bool pass = true;

    // Allocate host memory
    float *A_h = (float*)malloc(sizeBytes);
    float *B_h = (float*)malloc(sizeBytes);
    float *C_h = (float*)malloc(sizeBytes);

    // Allocate device pointers:
    // Unlike array_view, these must be explicitly managed by user:
    hc::accelerator acc;  // grab default accelerator where we want to allocate memory:
    hc::accelerator_view av = acc.get_default_view();

    float *A_d, *B_d, *C_d;
    A_d = hc::am_alloc(sizeBytes, acc, 0);
    B_d = hc::am_alloc(sizeBytes, acc, 0);
    C_d = hc::am_alloc(sizeBytes, acc, 0);

    // Initialize host data
    for (int i=0; i<sizeElements; i++) {
        A_h[i] = 1.618f * i; 
        B_h[i] = 3.142f * i;
        C_h[i] = 0;
    }

    av.copy(A_h, A_d, sizeBytes); // C++ copy H2D
    av.copy(B_h, B_d, sizeBytes); // C++ copy H2D

    // Launch kernel onto AV.  
    // Because the kernel PFE and the copies are submitted to same AV, they will execute in order
    // and we don't need additional synchronization to ensure the copies complete before the PFE begins.
    hc::completion_future cf=
    hc::parallel_for_each(av,  hc::extent<1> (sizeElements),
      [=] (hc::index<1> idx) [[hc]] { 
        int i = idx[0];
        C_d[i] = A_d[i] + B_d[i];
    });

   
    // This copy is in same AV as the kernel and thus will wait for the kernel to finish before executing.
    av.copy(C_d, C_h, sizeBytes); // C++ copy D2H


    for (int i=0; i<sizeElements; i++) {
        float ref= 1.618f * i + 3.142f * i;
        if (C_h[i] != ref) {
            printf ("error:%d computed=%6.2f, reference=%6.2f\n", i, C_h[i], ref);
            pass = false;
        }
    };
    if (pass) printf ("PASSED!\n");
}