Partial OpenCL support via SYCL compatible with ComputeCpp CE.

unsupported/Eigen/CXX11/src/Tensor/TensorDeviceSycl.h

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+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// Copyright (C) 2016 Benoit Steiner <benoit.steiner.goog@gmail.com>
+// Mehdi Goli    Codeplay Software Ltd.
+// Ralph Potter  Codeplay Software Ltd.
+// Luke Iwanski  Codeplay Software Ltd.
+// Cummins Chris PhD student at The University of Edinburgh.
+// Contact: <eigen@codeplay.com>
+
+//
+// This Source Code Form is subject to the terms of the Mozilla
+// Public License v. 2.0. If a copy of the MPL was not distributed
+// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#if defined(EIGEN_USE_SYCL) && !defined(EIGEN_CXX11_TENSOR_TENSOR_DEVICE_SYCL_H)
+#define EIGEN_CXX11_TENSOR_TENSOR_DEVICE_SYCL_H
+
+namespace Eigen {
+/// \struct BufferT is used to specialise add_sycl_buffer function for
+//  two types of buffer we have. When the MapAllocator is true, we create the
+//  sycl buffer with MapAllocator.
+/// We have to const_cast the input pointer in order to work around the fact
+/// that sycl does not accept map allocator for const pointer.
+template <typename T, bool MapAllocator>
+struct BufferT {
+  using Type = cl::sycl::buffer<T, 1, cl::sycl::map_allocator<T>>;
+  static inline void add_sycl_buffer(
+      const T *ptr, size_t num_bytes,
+      std::map<const void *, std::shared_ptr<void>> &buffer_map) {
+    buffer_map.insert(std::pair<const void *, std::shared_ptr<void>>(
+        ptr, std::shared_ptr<void>(std::make_shared<Type>(
+                 Type(const_cast<T *>(ptr), cl::sycl::range<1>(num_bytes))))));
+  }
+};
+
+/// specialisation of the \ref BufferT when the MapAllocator is false. In this
+/// case we only create the device-only buffer.
+template <typename T>
+struct BufferT<T, false> {
+  using Type = cl::sycl::buffer<T, 1>;
+  static inline void add_sycl_buffer(
+      const T *ptr, size_t num_bytes,
+      std::map<const void *, std::shared_ptr<void>> &buffer_map) {
+    buffer_map.insert(std::pair<const void *, std::shared_ptr<void>>(
+        ptr, std::shared_ptr<void>(
+                 std::make_shared<Type>(Type(cl::sycl::range<1>(num_bytes))))));
+  }
+};
+
+struct SyclDevice {
+  /// class members
+  /// sycl queue
+  cl::sycl::queue &m_queue;
+  /// std::map is the container used to make sure that we create only one buffer
+  /// per pointer. The lifespan of the buffer
+  /// now depends on the lifespan of SyclDevice. If a non-read-only pointer is
+  /// needed to be accessed on the host we should manually deallocate it.
+  mutable std::map<const void *, std::shared_ptr<void>> buffer_map;
+
+  SyclDevice(cl::sycl::queue &q) : m_queue(q) {}
+  // destructor
+  ~SyclDevice() { deallocate_all(); }
+
+  template <typename T>
+  void deallocate(const T *p) const {
+    auto it = buffer_map.find(p);
+    if (it != buffer_map.end()) {
+      buffer_map.erase(it);
+    }
+  }
+  void deallocate_all() const { buffer_map.clear(); }
+
+  /// creation of sycl accessor for a buffer. This function first tries to find
+  /// the buffer in the buffer_map.
+  /// If found it gets the accessor from it, if not, the function then adds an
+  /// entry by creating a sycl buffer
+  /// for that particular pointer.
+  template <cl::sycl::access::mode AcMd, bool MapAllocator, typename T>
+  inline cl::sycl::accessor<T, 1, AcMd, cl::sycl::access::target::global_buffer>
+  get_sycl_accessor(size_t num_bytes, cl::sycl::handler &cgh,
+                    const T *ptr) const {
+    auto it = buffer_map.find(ptr);
+    if (it == buffer_map.end()) {
+      BufferT<T, MapAllocator>::add_sycl_buffer(ptr, num_bytes, buffer_map);
+    }
+    return (
+        ((typename BufferT<T, MapAllocator>::Type *)(buffer_map.at(ptr).get()))
+            ->template get_access<AcMd>(cgh));
+  }
+
+  /// allocating memory on the cpu
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void *allocate(size_t num_bytes) const {
+    return internal::aligned_malloc(num_bytes);
+  }
+
+  // some runtime conditions that can be applied here
+  bool isDeviceSuitable() const { return true; }
+
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void deallocate(void *buffer) const {
+    internal::aligned_free(buffer);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void memcpy(void *dst, const void *src,
+                                                    size_t n) const {
+    ::memcpy(dst, src, n);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void memcpyHostToDevice(
+      void *dst, const void *src, size_t n) const {
+    memcpy(dst, src, n);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void memcpyDeviceToHost(
+      void *dst, const void *src, size_t n) const {
+    memcpy(dst, src, n);
+  }
+  EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void memset(void *buffer, int c,
+                                                    size_t n) const {
+    ::memset(buffer, c, n);
+  }
+};
+}  // end namespace Eigen
+
+#endif  // EIGEN_CXX11_TENSOR_TENSOR_DEVICE_SYCL_H