[SYCL] Add support multidimensional subscript for atomic accessor (#3473)

Signed-off-by: mdimakov <[email protected]>

Author: maximdimakov

sycl/include/CL/sycl/accessor.hpp

@@ -288,6 +288,8 @@ class accessor_common {
   constexpr static bool IsAccessReadWrite =
       AccessMode == access::mode::read_write;
 
+  constexpr static bool IsAccessAtomic = AccessMode == access::mode::atomic;
+
   using RefType = detail::const_if_const_AS<AS, DataT> &;
   using ConstRefType = const DataT &;
   using PtrType = detail::const_if_const_AS<AS, DataT> *;
@@ -327,6 +329,14 @@ class accessor_common {
       return MAccessor[MIDs];
     }
 
+    template <int CurDims = SubDims>
+    typename detail::enable_if_t<CurDims == 1 && IsAccessAtomic,
+                                 atomic<DataT, AS>>
+    operator[](size_t Index) const {
+      MIDs[Dims - CurDims] = Index;
+      return MAccessor[MIDs];
+    }
+
     template <int CurDims = SubDims,
               typename = detail::enable_if_t<CurDims == 1 && IsAccessReadOnly>>
     ConstRefType operator[](size_t Index) const {