--- /dev/null	2020-09-04 12:37:41.765504620 +0200
+++ new/test/hotspot/gtest/metaspace/metaspaceGtestCommon.cpp	2020-09-04 13:58:12.549502244 +0200
@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020 SAP SE. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+
+#include "runtime/os.hpp"
+
+#include "metaspaceGtestCommon.hpp"
+#include "metaspaceGtestRangeHelpers.hpp"
+
+
+void zap_range(MetaWord* p, size_t word_size) {
+  for (MetaWord* pzap = p; pzap < p + word_size; pzap += os::vm_page_size() / BytesPerWord) {
+    *pzap = (MetaWord)NOT_LP64(0xFEFEFEFE) LP64_ONLY(0xFEFEFEFEEFEFEFEFULL);
+  }
+}
+
+// Writes a unique pattern to p
+void mark_address(MetaWord* p, uintx pattern) {
+  MetaWord x = (MetaWord)((uintx) p ^ pattern);
+  *p = x;
+}
+
+// checks pattern at address
+void check_marked_address(const MetaWord* p, uintx pattern) {
+  MetaWord x = (MetaWord)((uintx) p ^ pattern);
+  EXPECT_EQ(*p, x);
+}
+
+// "fill_range_with_pattern" fills a range of heap words with pointers to itself.
+//
+// The idea is to fill a memory range with a pattern which is both marked clearly to the caller
+// and cannot be moved without becoming invalid.
+//
+// The filled range can be checked with check_range_for_pattern. One also can only check
+// a sub range of the original range.
+void fill_range_with_pattern(MetaWord* p, size_t word_size, uintx pattern) {
+  assert(word_size > 0 && p != NULL, "sanity");
+  for (MetaWord* p2 = p; p2 < p + word_size; p2++) {
+    mark_address(p2, pattern);
+  }
+}
+
+void check_range_for_pattern(const MetaWord* p, size_t word_size, uintx pattern) {
+  assert(p != NULL, "sanity");
+  const MetaWord* p2 = p;
+  while (p2 < p + word_size) {
+    check_marked_address(p2, pattern);
+    p2++;
+  }
+}
+
+// Similar to fill_range_with_pattern, but only marks start and end. This is optimized for cases
+// where fill_range_with_pattern just is too slow.
+// Use check_marked_range to check the range. In contrast to check_range_for_pattern, only the original
+// range can be checked.
+void mark_range(MetaWord* p, size_t word_size, uintx pattern) {
+  assert(word_size > 0 && p != NULL, "sanity");
+  mark_address(p, pattern);
+  mark_address(p + word_size - 1, pattern);
+}
+
+void check_marked_range(const MetaWord* p, size_t word_size, uintx pattern) {
+  assert(word_size > 0 && p != NULL, "sanity");
+  check_marked_address(p, pattern);
+  check_marked_address(p + word_size - 1, pattern);
+}
+
+void mark_range(MetaWord* p, size_t word_size) {
+  assert(word_size > 0 && p != NULL, "sanity");
+  uintx pattern = (uintx)p2i(p);
+  mark_range(p, word_size, pattern);
+}
+
+void check_marked_range(const MetaWord* p, size_t word_size) {
+  uintx pattern = (uintx)p2i(p);
+  check_marked_range(p, word_size, pattern);
+}
+