[SYCL][NFC] Use regular accessors for USM reductions (#1962)

The patch changes the type of accessors for USM reductions.
Placeholder accessors were used previously. Regular accessors are used now.

Also, the patch fixes few inaccurate or wrong comment sections.

Signed-off-by: Vyacheslav N Klochkov <[email protected]>

Author: v-klochkov

sycl/include/CL/sycl/handler.hpp

@@ -983,7 +983,7 @@ class __SYCL_EXPORT handler {
                                           RWAcc);
     this->finalize();
 
-    // Copy from RWAcc to some temp memory.
+    // Copy from RWAcc to user's reduction accessor.
     handler CopyHandler(QueueCopy, MIsHost);
     CopyHandler.saveCodeLoc(MCodeLoc);
 #ifndef __SYCL_DEVICE_ONLY__

sycl/include/CL/sycl/intel/reduction.hpp

@@ -1001,8 +1001,8 @@ reduAuxCGFunc(handler &CGH, const nd_range<Dims> &Range, size_t NWorkItems,
 
 /// Creates and returns an object implementing the reduction functionality.
 /// Accepts 3 arguments: the accessor to buffer to where the computed reduction
-/// must be stored \param Acc, identity value \param Identity, and the
-/// binary operation that must be used in the reduction \param Combiner.
+/// must be stored \param Acc, identity value \param Identity, and the binary
+/// operation used in the reduction.
 template <typename T, class BinaryOperation, int Dims, access::mode AccMode,
           access::placeholder IsPH>
 detail::reduction_impl<T, BinaryOperation, Dims, false, AccMode, IsPH>
@@ -1015,8 +1015,7 @@ reduction(accessor<T, Dims, AccMode, access::target::global_buffer, IsPH> &Acc,
 
 /// Creates and returns an object implementing the reduction functionality.
 /// Accepts 2 arguments: the accessor to buffer to where the computed reduction
-/// must be stored \param Acc and the binary operation that must be used
-/// in the reduction \param Combiner.
+/// must be stored \param Acc and the binary operation used in the reduction.
 /// The identity value is not passed to this version as it is statically known.
 template <typename T, class BinaryOperation, int Dims, access::mode AccMode,
           access::placeholder IsPH>
@@ -1032,37 +1031,27 @@ reduction(accessor<T, Dims, AccMode, access::target::global_buffer, IsPH> &Acc,
 
 /// Creates and returns an object implementing the reduction functionality.
 /// Accepts 3 arguments: the reference to the reduction variable to where
-/// the computed reduction must be stored \param VarRef, identity value
-/// \param Identity, and the binary operation that must be used
-/// in the reduction \param Combiner.
+/// the computed reduction must be stored \param VarPtr, identity value
+/// \param Identity, and the binary operation used in the reduction.
 template <typename T, class BinaryOperation>
-detail::reduction_impl<T, BinaryOperation, 0, true, access::mode::read_write,
-                       access::placeholder::true_t>
-reduction(T *VarPtr, const T &Identity, BinaryOperation Combiner) {
-  // The Combiner argument was needed only to define the BinaryOperation param.
-  (void)Combiner;
+detail::reduction_impl<T, BinaryOperation, 0, true, access::mode::read_write>
+reduction(T *VarPtr, const T &Identity, BinaryOperation) {
   return detail::reduction_impl<T, BinaryOperation, 0, true,
-                                access::mode::read_write,
-                                access::placeholder::true_t>(VarPtr, Identity);
+                                access::mode::read_write>(VarPtr, Identity);
 }
 
 /// Creates and returns an object implementing the reduction functionality.
-/// Accepts 3 arguments: the reference to the reduction variable to where
-/// the computed reduction must be stored \param VarRef, identity value
-/// \param Identity, and the binary operation that must be used
-/// in the reduction \param Combiner.
+/// Accepts 2 arguments: the reference to the reduction variable, to where
+/// the computed reduction must be stored \param VarPtr, and the binary
+/// operation used in the reduction.
 /// The identity value is not passed to this version as it is statically known.
 template <typename T, class BinaryOperation>
 detail::enable_if_t<detail::IsKnownIdentityOp<T, BinaryOperation>::value,
                     detail::reduction_impl<T, BinaryOperation, 0, true,
-                                           access::mode::read_write,
-                                           access::placeholder::true_t>>
-reduction(T *VarPtr, BinaryOperation Combiner) {
-  // The Combiner argument was needed only to define the BinaryOperation param.
-  (void)Combiner;
+                                           access::mode::read_write>>
+reduction(T *VarPtr, BinaryOperation) {
   return detail::reduction_impl<T, BinaryOperation, 0, true,
-                                access::mode::read_write,
-                                access::placeholder::true_t>(VarPtr);
+                                access::mode::read_write>(VarPtr);
 }
 
 } // namespace intel