[SYCL-2020]- null placeholder accessor issue in Reduction SYCL test

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

@@ -794,6 +794,17 @@ class QueueInterface {
 #endif
   }
 
+  template <typename T>
+  EIGEN_STRONG_INLINE TensorSycl::internal::RangeAccess<cl::sycl::access::mode::read_write, T> get_null_accessor()
+      const {
+    eigen_assert(null_buff_simulator.get_size() % sizeof(T) == 0 && "The null buffer size must be a multiple of sizeof(T)");
+    const ptrdiff_t typed_size = null_buff_simulator.get_size() / sizeof(T);
+    eigen_assert(typed_size > 0);
+    auto typed_null_buff =
+        null_buff_simulator.template reinterpret<T>(cl::sycl::range<1>(typed_size));
+    return TensorSycl::internal::RangeAccess<cl::sycl::access::mode::read_write, T>(typed_null_buff);
+  }
+
  protected:
   EIGEN_STRONG_INLINE void set_latest_event(cl::sycl::event e) const {
 #ifdef EIGEN_SYCL_STORE_LATEST_EVENT
@@ -852,6 +863,7 @@ class QueueInterface {
   /// SyclDevice. If a non-read-only pointer is needed to be accessed on the
   /// host we should manually deallocate it.
   mutable TensorSycl::internal::PointerMapper pMapper;
+  cl::sycl::buffer<uint8_t, 1> null_buff_simulator = cl::sycl::buffer<uint8_t, 1>(cl::sycl::range<1>(128));
 #ifndef EIGEN_SYCL_NO_REUSE_BUFFERS
   mutable std::unordered_set<void *> scratch_buffers;
 #endif
@@ -885,6 +897,11 @@ struct SyclDevice : public SyclDeviceBase {
   explicit SyclDevice(const QueueInterface *queue_stream)
       : SyclDeviceBase(queue_stream) {}
  
+  template <typename scalar_t>
+  EIGEN_STRONG_INLINE TensorSycl::internal::RangeAccess<cl::sycl::access::mode::read_write, scalar_t>
+  get_null_accessor() const {
+    return queue_stream()->template get_null_accessor<scalar_t>();
+  }
   // this is the accessor used to construct the evaluator
   template <cl::sycl::access::mode AcMd, typename T>
   EIGEN_STRONG_INLINE TensorSycl::internal::RangeAccess<AcMd, T>

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

@@ -541,6 +541,24 @@ class TensorReductionOp : public TensorBase<TensorReductionOp<Op, Dims, XprType,
 template<typename ArgType, typename Device>
 struct TensorReductionEvaluatorBase;
 
+namespace internal {
+namespace reduction {
+
+template <typename CoeffReturnType, typename Device>
+EIGEN_ALWAYS_INLINE typename StorageMemory<CoeffReturnType, Device>::Type get_null_value(
+    typename std::enable_if<Eigen::internal::is_same<Device, Eigen::SyclDevice>::value, const Device>::type& dev) {
+    return (dev.template get_null_accessor<CoeffReturnType>());
+}
+
+template <typename CoeffReturnType, typename Device>
+EIGEN_ALWAYS_INLINE typename StorageMemory<CoeffReturnType, Device>::Type get_null_value(
+    typename std::enable_if<!Eigen::internal::is_same<Device, Eigen::SyclDevice>::value, const Device>::type&) {
+    return NULL;
+}
+
+}// end namespace reduction
+} // end namespace internal
+
 // Eval as rvalue
 template<typename Op, typename Dims, typename ArgType, template <class> class MakePointer_, typename Device>
 struct TensorReductionEvaluatorBase<const TensorReductionOp<Op, Dims, ArgType, MakePointer_>, Device>
@@ -603,8 +621,10 @@ static constexpr bool RunningOnGPU = false;
   static constexpr bool RunningFullReduction = (NumOutputDims==0);
 
   EIGEN_STRONG_INLINE TensorReductionEvaluatorBase(const XprType& op, const Device& device)
-      : m_impl(op.expression(), device), m_reducer(op.reducer()), m_result(NULL), m_device(device)
+      : m_impl(op.expression(), device),
-  {
+        m_reducer(op.reducer()),
+        m_result(internal::reduction::get_null_value<CoeffReturnType, Device>(device)),
+        m_device(device) {
     EIGEN_STATIC_ASSERT((NumInputDims >= NumReducedDims), YOU_MADE_A_PROGRAMMING_MISTAKE);
     EIGEN_STATIC_ASSERT((!ReducingInnerMostDims | !PreservingInnerMostDims | (NumReducedDims == NumInputDims)),
                         YOU_MADE_A_PROGRAMMING_MISTAKE);
@@ -895,7 +915,7 @@ static constexpr bool RunningOnGPU = false;
   // binding placeholder accessors to a command group handler for SYCL
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void bind(cl::sycl::handler &cgh) const {
     m_impl.bind(cgh);
-    if(m_result) m_result.bind(cgh);
+    m_result.bind(cgh);
   }
 #endif
 

unsupported/test/cxx11_tensor_device_sycl.cpp

@@ -26,8 +26,10 @@
 #ifdef SYCL_COMPILER_IS_DPCPP
 template <typename T>
 struct cl::sycl::is_device_copyable<
-    const OffByOneScalar<T>,
+    OffByOneScalar<T>,
-    std::enable_if_t<!std::is_trivially_copyable<const OffByOneScalar<T>>::value>> : std::true_type {};
+    std::enable_if_t<!(!std::is_trivially_copyable<OffByOneScalar<T>>::value &&
+                       (std::is_const_v<OffByOneScalar<T>> || std::is_volatile_v<OffByOneScalar<T>>))>>
+    : std::true_type {};
 #endif
 
 template <typename DataType, int DataLayout, typename IndexType>