/*

 * 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);

}