--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shared/barrierSetNMethod.cpp	Tue Oct 16 13:18:22 2018 +0200
@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. 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 "code/codeCache.hpp"
+#include "code/nmethod.hpp"
+#include "gc/shared/barrierSet.hpp"
+#include "gc/shared/barrierSetNMethod.hpp"
+#include "logging/log.hpp"
+#include "runtime/thread.hpp"
+#include "utilities/debug.hpp"
+
+int BarrierSetNMethod::disarmed_value() const {
+  char* disarmed_addr = reinterpret_cast<char*>(Thread::current());
+  disarmed_addr += in_bytes(thread_disarmed_offset());
+  return *reinterpret_cast<int*>(disarmed_addr);
+}
+
+bool BarrierSetNMethod::supports_entry_barrier(nmethod* nm) {
+  if (nm->method()->is_method_handle_intrinsic()) {
+    return false;
+  }
+
+  if (!nm->is_native_method() && !nm->is_compiled_by_c2() && !nm->is_compiled_by_c1()) {
+    return false;
+  }
+
+  return true;
+}
+
+int BarrierSetNMethod::nmethod_stub_entry_barrier(address* return_address_ptr) {
+  address return_address = *return_address_ptr;
+  CodeBlob* cb = CodeCache::find_blob(return_address);
+  assert(cb != NULL, "invariant");
+
+  nmethod* nm = cb->as_nmethod();
+  BarrierSetNMethod* bs_nm = BarrierSet::barrier_set()->barrier_set_nmethod();
+
+  if (!bs_nm->is_armed(nm)) {
+    return 0;
+  }
+
+  assert(!nm->is_osr_method(), "Should not reach here");
+  // Called upon first entry after being armed
+  bool may_enter = bs_nm->nmethod_entry_barrier(nm);
+  if (!may_enter) {
+    log_trace(nmethod, barrier)("Deoptimizing nmethod: " PTR_FORMAT, p2i(nm));
+    bs_nm->deoptimize(nm, return_address_ptr);
+  }
+  return may_enter ? 0 : 1;
+}
+
+bool BarrierSetNMethod::nmethod_osr_entry_barrier(nmethod* nm) {
+  // This check depends on the invariant that all nmethods that are deoptimized / made not entrant
+  // are NOT disarmed.
+  // This invariant is important because a method can be deoptimized after the method have been
+  // resolved / looked up by OSR by another thread. By not deoptimizing them we guarantee that
+  // a deoptimized method will always hit the barrier and come to the same conclusion - deoptimize
+  if (!is_armed(nm)) {
+    return true;
+  }
+
+  assert(nm->is_osr_method(), "Should not reach here");
+  log_trace(nmethod, barrier)("Running osr nmethod entry barrier: " PTR_FORMAT, p2i(nm));
+  return nmethod_entry_barrier(nm);
+}