Add kernel reduction example

examples/CMakeLists.txt

@@ -101,6 +101,11 @@ raja_add_executable(
   NAME kernel-dynamic-tile
   SOURCES kernel-dynamic-tile.cpp)
 
+raja_add_executable(
+  NAME kernel-reduction
+  SOURCES kernel-reduction.cpp)
+
+
 raja_add_executable(
   NAME resource-kernel
   SOURCES resource-kernel.cpp)

examples/kernel-reduction.cpp

@@ -0,0 +1,73 @@
+#include "RAJA/RAJA.hpp"
+#include "RAJA/index/RangeSegment.hpp"
+#include "memoryManager.hpp"
+
+
+int main(int RAJA_UNUSED_ARG(argc), char **RAJA_UNUSED_ARG(argv[]))
+{
+
+// matrix min, really dumb example
+using EXEC_POL8 =
+    RAJA::KernelPolicy<
+      RAJA::statement::CudaKernel<
+        RAJA::statement::For<1, RAJA::cuda_block_x_loop,    // row
+          RAJA::statement::For<0, RAJA::cuda_thread_x_loop, // col
+            RAJA::statement::Lambda<0>  // min addition do I need an extra , RAJA::Params<0> here?
+          >
+        >
+      >
+    >;
+  // _matmult_3lambdakernel_cuda_end
+
+  using VALOPLOC_INT_MIN = RAJA::expt::ValLocOp<int, RAJA::Index_type, RAJA::operators::minimum>;
+  using VALOP_INT_MIN = RAJA::expt::ValOp<int, RAJA::operators::minimum>;
+  // RAJA::expt::Reduce<RAJA::operators::minimum>(&cuda_min),
+  int cuda_min = 0;
+
+  int seq_sum = 0;
+  int N = 10000;
+
+  RAJA::TypedRangeSegment<int> row_range(0, N);
+  RAJA::TypedRangeSegment<int> col_range(0, N);
+
+  RAJA::resources::Cuda cuda_res;
+  int *A = memoryManager::allocate<int>(N * N);
+  for (int row = 0; row < N; ++row) {
+    for (int col = 0; col < N; ++col) {
+      A[col + row * N] = -row;
+    }
+  }
+
+  RAJA::View<int, RAJA::Layout<2>> Aview(A, N, N);
+
+  // doesn't compile: 
+  //      no known conversion from 
+  //      'RAJA::expt::detail::Reducer<RAJA::operators::minimum<int>, int, RAJA::expt::ValOp<int, RAJA::operators::minimum>>' 
+  //       to 'VALOP_INT_MIN &'
+  RAJA::kernel_param<EXEC_POL8>(
+    // segments
+    RAJA::make_tuple(col_range, row_range),
+    // params
+    RAJA::make_tuple(RAJA::expt::Reduce<RAJA::operators::minimum>(&cuda_min)),
+    //RAJA::tuple<double>(0.0),
+    // lambda 1
+    [=] RAJA_DEVICE (int col, int row, VALOP_INT_MIN &_cuda_min) {
+      _cuda_min.min(Aview(row, col));
+      //double& a){
+        //a += Aview(row, col);
+    }
+
+  );
+
+  // compiles
+  RAJA::forall<RAJA::cuda_exec<256>>(cuda_res, RAJA::RangeSegment(0, N),
+    RAJA::expt::Reduce<RAJA::operators::minimum>(&cuda_min),
+    [=] RAJA_DEVICE (int i, VALOP_INT_MIN &_cuda_min) {
+      _cuda_min.min(Aview(i, 0));
+    }
+
+  );
+
+  std::cout << "MIN VAL = " << cuda_min << std::endl;
+  //checkResult<double>(Cview, N);
+};

include/RAJA/kernel-reduce.cpp

@@ -0,0 +1,41 @@
+#include "RAJA/RAJA.hpp"
+
+using EXEC_POL8 =
+    RAJA::KernelPolicy<
+      RAJA::statement::CudaKernel<
+        RAJA::statement::For<1, RAJA::cuda_block_x_loop,    // row
+          RAJA::statement::For<0, RAJA::cuda_thread_x_loop, // col
+            RAJA::statement::Lambda<0, RAJA::Params<0>>,    // dot = 0.0
+            RAJA::statement::For<2, RAJA::seq_exec,
+                RAJA::statement::Lambda<1>                  // dot += ...
+            >,
+            RAJA::statement::Lambda<2, RAJA::Segs<0, 1>, RAJA::Params<0>>   // set C = ...
+          >
+        >
+      >
+    >;
+  // _matmult_3lambdakernel_cuda_end
+
+  RAJA::kernel_param<EXEC_POL8>(
+    RAJA::make_tuple(col_range, row_range, dot_range),
+
+    RAJA::tuple<double>{0.0},    // thread local variable for 'dot'
+
+    // lambda 0
+    [=] RAJA_DEVICE (double& dot) {
+       dot = 0.0;
+    },
+
+    // lambda 1
+    [=] RAJA_DEVICE (int col, int row, int k, double& dot) {
+       dot += Aview(row, k) * Bview(k, col);
+    },
+
+    // lambda 2
+    [=] RAJA_DEVICE (int col, int row, double& dot) {
+       Cview(row, col) = dot;
+    }
+
+  );
+
+  checkResult<double>(Cview, N);

include/RAJA/pattern/params/reducer.hpp

@@ -68,7 +68,7 @@ struct Reducer : public ForallParamBase
 {
   using op         = Op;
   using value_type = T;  // This is a basic data type
-
+  //using VOp = ValOp<T, Op>;
   Reducer() = default;
 
   // Basic data type constructor