[SYCL] Implement dot kernel

SYCLStream.cpp

@@ -13,6 +13,9 @@ using namespace cl::sycl;
 
 #define WGSIZE 256
 
+#define DOT_WGSIZE 256
+#define DOT_NUM_GROUPS 256
+
 // Cache list of devices
 bool cached = false;
 std::vector<device> devices;
@@ -48,6 +51,7 @@ SYCLStream<T>::SYCLStream(const unsigned int ARRAY_SIZE, const int device_index)
   d_a = new buffer<T>(array_size);
   d_b = new buffer<T>(array_size);
   d_c = new buffer<T>(array_size);
+  d_sum = new buffer<T>(DOT_NUM_GROUPS);
 }
 
 template <class T>
@@ -56,6 +60,7 @@ SYCLStream<T>::~SYCLStream()
   delete d_a;
   delete d_b;
   delete d_c;
+  delete d_sum;
 
   delete queue;
 }
@@ -124,6 +129,49 @@ void SYCLStream<T>::triad()
   queue->wait();
 }
 
+template <class T>
+T SYCLStream<T>::dot()
+{
+  queue->submit([&](handler &cgh)
+  {
+    auto ka   = d_a->template get_access<access::mode::read>(cgh);
+    auto kb   = d_b->template get_access<access::mode::read>(cgh);
+    auto ksum = d_sum->template get_access<access::mode::write>(cgh);
+
+    auto wg_sum = accessor<T, 1, access::mode::read_write, access::target::local>(range<1>(DOT_WGSIZE), cgh);
+
+    size_t N = array_size;
+
+    cgh.parallel_for<class dot>(nd_range<1>(DOT_NUM_GROUPS*DOT_WGSIZE, DOT_WGSIZE), [=](nd_item<1> item)
+    {
+      size_t i = item.get_global(0);
+      size_t li = item.get_local(0);
+      wg_sum[li] = 0.0;
+      for (; i < N; i += item.get_global_range()[0])
+        wg_sum[li] += ka[i] * kb[i];
+
+      for (int offset = item.get_local_range()[0]; offset > 0; offset /= 2)
+      {
+        item.barrier(cl::sycl::access::fence_space::local_space);
+        if (li < offset)
+          wg_sum[li] += wg_sum[li + offset];
+      }
+
+      if (li == 0)
+        ksum[item.get_group(0)] = wg_sum[0];
+    });
+  });
+
+  T sum = 0.0;
+  auto h_sum = d_sum->template get_access<access::mode::read, access::target::host_buffer>();
+  for (int i = 0; i < DOT_NUM_GROUPS; i++)
+  {
+    sum += h_sum[i];
+  }
+
+  return sum;
+}
+
 template <class T>
 void SYCLStream<T>::write_arrays(const std::vector<T>& a, const std::vector<T>& b, const std::vector<T>& c)
 {

SYCLStream.h

@@ -27,6 +27,7 @@ class SYCLStream : public Stream<T>
     cl::sycl::buffer<T> *d_a;
     cl::sycl::buffer<T> *d_b;
     cl::sycl::buffer<T> *d_c;
+    cl::sycl::buffer<T> *d_sum;
 
   public:
 
@@ -37,6 +38,7 @@ class SYCLStream : public Stream<T>
     virtual void add() override;
     virtual void mul() override;
     virtual void triad() override;
+    virtual T    dot() override;
 
     virtual void write_arrays(const std::vector<T>& a, const std::vector<T>& b, const std::vector<T>& c) override;
     virtual void read_arrays(std::vector<T>& a, std::vector<T>& b, std::vector<T>& c) override;