From e685d35e2af951cd4dba5cb01fe215f22d5e7944 Mon Sep 17 00:00:00 2001
From: Alan Dayton <dayton8@llnl.gov>
Date: Tue, 11 Apr 2023 13:56:12 -0700
Subject: [PATCH] Improvements to ArrayView interface

---
 benchmarks/BenchmarkArrayView.cpp |  2 +-
 src/care/ArrayView.h              | 62 +++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+), 1 deletion(-)

diff --git a/benchmarks/BenchmarkArrayView.cpp b/benchmarks/BenchmarkArrayView.cpp
index d6f4a1ea..7341d477 100644
--- a/benchmarks/BenchmarkArrayView.cpp
+++ b/benchmarks/BenchmarkArrayView.cpp
@@ -19,7 +19,7 @@ static void benchmark_array_view_2d(benchmark::State& state) {
    const int extent2 = state.range(0);
    care::host_device_ptr<int> data(extent1*extent2, "data");
 
-   // Make sure memory transfers are not considered
+   // Make sure memory transfers are not considered in the timing
    auto temp = care::makeArrayView2D(data, extent1, extent2);
    (void) temp;
 
diff --git a/src/care/ArrayView.h b/src/care/ArrayView.h
index 5052f0fb..55587ced 100644
--- a/src/care/ArrayView.h
+++ b/src/care/ArrayView.h
@@ -6,6 +6,23 @@
 #include "RAJA/util/View.hpp"
 
 namespace care {
+   template <class T>
+   using ArrayView1D = RAJA::View<T, RAJA::Layout<1>>;
+
+   template <class T>
+   using ArrayCView1D = ArrayView1D<const T>;
+
+#if defined(CARE_GPUCC)
+   template <class T>
+   using ArrayView2D = RAJA::View<T, RAJA::Layout<2, int, 1>>;
+#else
+   template <class T>
+   using ArrayView2D = RAJA::View<T, RAJA::Layout<2, int, 0>>;
+#endif
+
+   template <class T>
+   using ArrayCView2D = ArrayView2D<const T>;
+
    ///
    /// Creates a 1D view on top of a flat allocation (non-owning semantics)
    ///
@@ -21,6 +38,21 @@ namespace care {
    auto makeArrayView1D(care::host_device_ptr<T> data,
                         int extent);
 
+   ///
+   /// Creates a 1D const view on top of a flat allocation (non-owning semantics)
+   ///
+   /// Moves the data to the default execution space (determined at
+   /// compile time) and wraps it in a RAJA::View.
+   ///
+   /// @param[in] data Container for the allocation
+   /// @param[in] extent Length of the view
+   ///
+   /// @return A RAJA::View object
+   ///
+   template <class T>
+   auto makeArrayCView1D(care::host_device_ptr<T> data,
+                         int extent);
+
    ///
    /// Creates a 2D view on top of a flat allocation (non-owning semantics)
    ///
@@ -38,6 +70,24 @@ namespace care {
    template <class T>
    auto makeArrayView2D(care::host_device_ptr<T> data,
                         int extent1, int extent2);
+
+   ///
+   /// Creates a 2D const view on top of a flat allocation (non-owning semantics)
+   ///
+   /// Moves the data to the default execution space (determined at
+   /// compile time) and wraps it in a RAJA::View. When using with a
+   /// RAJA loop, extent2 should correspond to the length of the RAJA
+   /// loop for optimal performance.
+   ///
+   /// @param[in] data Container for the allocation
+   /// @param[in] extent1 Length of the 1st dimension
+   /// @param[in] extent2 Length of the 2nd dimension
+   ///
+   /// @return A RAJA::View object
+   ///
+   template <class T>
+   auto makeArrayCView2D(care::host_device_ptr<T> data,
+                         int extent1, int extent2);
    
    template <class T>
    auto makeArrayView1D(care::host_device_ptr<T> data,
@@ -49,6 +99,12 @@ namespace care {
 #endif
    }
 
+   template <class T>
+   auto makeArrayCView1D(care::host_device_ptr<T> data,
+                         int extent) {
+      return makeArrayView1D(care::host_device_ptr<T const>(data), extent);
+   }
+
    template <class T>
    auto makeArrayView2D(care::host_device_ptr<T> data,
                         int extent1, int extent2) {
@@ -62,6 +118,12 @@ namespace care {
       return RAJA::View<T, RAJA::Layout<2, int, 0>>(data.data(chai::CPU), layout);
 #endif
    }
+
+   template <class T>
+   auto makeArrayCView2D(care::host_device_ptr<T> data,
+                         int extent1, int extent2) {
+      return makeArrayView2D(care::host_device_ptr<T const>(data), extent1, extent2);
+   }
 } // namespace care
 
 #endif // CARE_ARRAY_VIEW_H