[SYCL] Use the user-provided host ptr if alignment is sufficient

Reuse the pointer provided by the user in the buffer constructor (even
if use_host_ptr wasn't specified) if its alignment is sufficient.

Signed-off-by: Sergey Semenov <sergey.semenov@intel.com>

Author: sergey-semenov

sycl/include/CL/sycl/detail/buffer_impl.hpp

@@ -22,6 +22,7 @@
 #include <CL/sycl/stl.hpp>
 #include <CL/sycl/types.hpp>
 
+#include <cstdint>
 #include <functional>
 #include <memory>
 #include <type_traits>
@@ -59,7 +60,10 @@ template <typename AllocatorT> class buffer_impl : public SYCLMemObjT {
       return;
 
     set_final_data(reinterpret_cast<char *>(HostData));
-    if (MProps.has_property<property::buffer::use_host_ptr>()) {
+    size_t RequiredAlignment =
+        getNextPowerOfTwo(sizeof(typename AllocatorT::value_type));
+    if (reinterpret_cast<std::uintptr_t>(HostData) % RequiredAlignment == 0 ||
+        MProps.has_property<property::buffer::use_host_ptr>()) {
       MUserPtr = HostData;
       return;
     }