[SYCL] Fix mismatch between sub_group headers (#1215)

sub_group::store took T& for host and const T& for device.

Signed-off-by: John Pennycook <[email protected]>

Author: Pennycook

sycl/include/CL/sycl/intel/sub_group_host.hpp

@@ -136,7 +136,7 @@ struct sub_group {
   }
 
   template <typename T, access::address_space Space>
-  void store(multi_ptr<T, Space> dst, T &x) const {
+  void store(multi_ptr<T, Space> dst, const T &x) const {
     throw runtime_error("Subgroups are not supported on host device. ");
   }
 

sycl/test/regression/sub-group-store-const-ref.cpp

@@ -0,0 +1,16 @@
+// RUN: %clangxx -I %sycl_include -fsyntax-only -Xclang -verify %s
+// expected-no-diagnostics
+//
+//==-- sub-group-store-const-ref.cpp ---------------------------------------==//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+// This test checks that sub_group::store supports const reference.
+//===----------------------------------------------------------------------===//
+#include <CL/sycl.hpp>
+using namespace sycl;
+
+void test(intel::sub_group sg, global_ptr<int> ptr) { sg.store(ptr, 1); }