[NFCI][SYCL] Refactor reductions implementations

sycl/include/sycl/handler.hpp

@@ -30,6 +30,7 @@
 #include <sycl/nd_item.hpp>
 #include <sycl/nd_range.hpp>
 #include <sycl/property_list.hpp>
+#include <sycl/reduction_forward.hpp>
 #include <sycl/sampler.hpp>
 #include <sycl/stl.hpp>
 
@@ -268,43 +269,9 @@ class RoundedRangeKernelWithKH {
   KernelType KernelFunc;
 };
 
-template <typename T, class BinaryOperation, int Dims, size_t Extent,
-          typename RedOutVar>
-class reduction_impl_algo;
-
 using sycl::detail::enable_if_t;
 using sycl::detail::queue_impl;
 
-// Reductions implementation need access to private members of handler. Those
-// are limited to those below.
-namespace reduction {
-inline void finalizeHandler(handler &CGH);
-template <class FunctorTy> void withAuxHandler(handler &CGH, FunctorTy Func);
-} // namespace reduction
-
-template <typename KernelName, int Dims, typename PropertiesT,
-          typename KernelType, typename Reduction>
-void reduction_parallel_for(handler &CGH,
-                            std::shared_ptr<detail::queue_impl> Queue,
-                            range<Dims> Range, PropertiesT Properties,
-                            Reduction Redu, KernelType KernelFunc);
-
-template <typename KernelName, int Dims, typename PropertiesT,
-          typename KernelType, typename Reduction>
-void reduction_parallel_for(handler &CGH,
-                            std::shared_ptr<detail::queue_impl> Queue,
-                            nd_range<Dims> Range, PropertiesT Properties,
-                            Reduction Redu, KernelType KernelFunc);
-
-template <typename KernelName, int Dims, typename PropertiesT,
-          typename... RestT>
-void reduction_parallel_for(handler &CGH,
-                            std::shared_ptr<detail::queue_impl> Queue,
-                            nd_range<Dims> Range, PropertiesT Properties,
-                            RestT... Rest);
-
-template <typename T> struct IsReduction;
-template <typename FirstT, typename... RestT> struct AreAllButLastReductions;
 } // namespace detail
 
 /// Command group handler class.