[NFC][SYCL] Add pragma unroll in accessor.hpp

sycl/include/CL/sycl/accessor.hpp

@@ -834,6 +834,14 @@ class accessor :
 #endif // __SYCL_DEVICE_ONLY__
 
     size_t Result = 0;
+    // Unroll the following loop for both host and device code
+#if defined(__clang__) || defined(__INTEL_COMPILER)
+#pragma unroll
+#elif defined(__GNUC__) || defined(__GNUG__)
+#pragma GCC unroll 3
+#elif defined(_MSC_VER)
+    // MSVC pragma loop doesn't have unroll option
+#endif // switch over the compilers is over
     for (int I = 0; I < Dims; ++I)
       Result = Result * getMemoryRange()[I] + getOffset()[I] + Id[I];
     return Result;