jdk

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/*
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 * Copyright (c) 2005, 2024, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 *
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 */
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#include "precompiled.hpp"
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#include "ci/ciArrayKlass.hpp"
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#include "ci/ciEnv.hpp"
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#include "ci/ciKlass.hpp"
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#include "ci/ciMethod.hpp"
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#include "classfile/javaClasses.inline.hpp"
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#include "classfile/vmClasses.hpp"
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#include "code/dependencies.hpp"
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#include "compiler/compileLog.hpp"
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#include "compiler/compileBroker.hpp"
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#include "compiler/compileTask.hpp"
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#include "memory/resourceArea.hpp"
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#include "oops/klass.hpp"
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#include "oops/oop.inline.hpp"
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#include "oops/method.inline.hpp"
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#include "oops/objArrayKlass.hpp"
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#include "runtime/flags/flagSetting.hpp"
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#include "runtime/handles.hpp"
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#include "runtime/handles.inline.hpp"
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#include "runtime/javaThread.inline.hpp"
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#include "runtime/jniHandles.inline.hpp"
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#include "runtime/mutexLocker.hpp"
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#include "runtime/perfData.hpp"
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#include "runtime/vmThread.hpp"
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#include "utilities/copy.hpp"
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#ifdef ASSERT
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static bool must_be_in_vm() {
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  Thread* thread = Thread::current();
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  if (thread->is_Java_thread()) {
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    return JavaThread::cast(thread)->thread_state() == _thread_in_vm;
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  } else {
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    return true;  // Could be VMThread or GC thread
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  }
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}
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#endif //ASSERT
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bool Dependencies::_verify_in_progress = false;  // don't -Xlog:dependencies
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void Dependencies::initialize(ciEnv* env) {
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  Arena* arena = env->arena();
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  _oop_recorder = env->oop_recorder();
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  _log = env->log();
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  _dep_seen = new(arena) GrowableArray<int>(arena, 500, 0, 0);
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#if INCLUDE_JVMCI
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  _using_dep_values = false;
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#endif
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  DEBUG_ONLY(_deps[end_marker] = nullptr);
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  for (int i = (int)FIRST_TYPE; i < (int)TYPE_LIMIT; i++) {
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    _deps[i] = new(arena) GrowableArray<ciBaseObject*>(arena, 10, 0, nullptr);
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  }
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  _content_bytes = nullptr;
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  _size_in_bytes = (size_t)-1;
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  assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT), "sanity");
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}
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void Dependencies::assert_evol_method(ciMethod* m) {
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  assert_common_1(evol_method, m);
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}
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void Dependencies::assert_leaf_type(ciKlass* ctxk) {
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  if (ctxk->is_array_klass()) {
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    // As a special case, support this assertion on an array type,
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    // which reduces to an assertion on its element type.
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    // Note that this cannot be done with assertions that
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    // relate to concreteness or abstractness.
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    ciType* elemt = ctxk->as_array_klass()->base_element_type();
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    if (!elemt->is_instance_klass())  return;   // Ex:  int[][]
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    ctxk = elemt->as_instance_klass();
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    //if (ctxk->is_final())  return;            // Ex:  String[][]
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  }
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  check_ctxk(ctxk);
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  assert_common_1(leaf_type, ctxk);
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}
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void Dependencies::assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck) {
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  check_ctxk_abstract(ctxk);
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  assert_common_2(abstract_with_unique_concrete_subtype, ctxk, conck);
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}
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void Dependencies::assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm) {
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  check_ctxk(ctxk);
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  check_unique_method(ctxk, uniqm);
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  assert_common_2(unique_concrete_method_2, ctxk, uniqm);
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}
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void Dependencies::assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm, ciKlass* resolved_klass, ciMethod* resolved_method) {
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  check_ctxk(ctxk);
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  check_unique_method(ctxk, uniqm);
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  assert_common_4(unique_concrete_method_4, ctxk, uniqm, resolved_klass, resolved_method);
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}
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void Dependencies::assert_unique_implementor(ciInstanceKlass* ctxk, ciInstanceKlass* uniqk) {
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  check_ctxk(ctxk);
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  check_unique_implementor(ctxk, uniqk);
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  assert_common_2(unique_implementor, ctxk, uniqk);
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}
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void Dependencies::assert_has_no_finalizable_subclasses(ciKlass* ctxk) {
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  check_ctxk(ctxk);
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  assert_common_1(no_finalizable_subclasses, ctxk);
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}
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void Dependencies::assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle) {
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  assert_common_2(call_site_target_value, call_site, method_handle);
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}
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#if INCLUDE_JVMCI
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Dependencies::Dependencies(Arena* arena, OopRecorder* oop_recorder, CompileLog* log) {
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  _oop_recorder = oop_recorder;
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  _log = log;
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  _dep_seen = new(arena) GrowableArray<int>(arena, 500, 0, 0);
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  _using_dep_values = true;
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  DEBUG_ONLY(_dep_values[end_marker] = nullptr);
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  for (int i = (int)FIRST_TYPE; i < (int)TYPE_LIMIT; i++) {
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    _dep_values[i] = new(arena) GrowableArray<DepValue>(arena, 10, 0, DepValue());
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  }
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  _content_bytes = nullptr;
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  _size_in_bytes = (size_t)-1;
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  assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT), "sanity");
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}
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void Dependencies::assert_evol_method(Method* m) {
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  assert_common_1(evol_method, DepValue(_oop_recorder, m));
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}
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void Dependencies::assert_has_no_finalizable_subclasses(Klass* ctxk) {
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  check_ctxk(ctxk);
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  assert_common_1(no_finalizable_subclasses, DepValue(_oop_recorder, ctxk));
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}
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void Dependencies::assert_leaf_type(Klass* ctxk) {
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  if (ctxk->is_array_klass()) {
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    // As a special case, support this assertion on an array type,
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    // which reduces to an assertion on its element type.
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    // Note that this cannot be done with assertions that
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    // relate to concreteness or abstractness.
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    BasicType elemt = ArrayKlass::cast(ctxk)->element_type();
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    if (is_java_primitive(elemt))  return;   // Ex:  int[][]
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    ctxk = ObjArrayKlass::cast(ctxk)->bottom_klass();
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    //if (ctxk->is_final())  return;            // Ex:  String[][]
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  }
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  check_ctxk(ctxk);
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  assert_common_1(leaf_type, DepValue(_oop_recorder, ctxk));
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}
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void Dependencies::assert_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck) {
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  check_ctxk_abstract(ctxk);
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  DepValue ctxk_dv(_oop_recorder, ctxk);
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  DepValue conck_dv(_oop_recorder, conck, &ctxk_dv);
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  assert_common_2(abstract_with_unique_concrete_subtype, ctxk_dv, conck_dv);
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}
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void Dependencies::assert_unique_implementor(InstanceKlass* ctxk, InstanceKlass* uniqk) {
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  check_ctxk(ctxk);
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  assert(ctxk->is_interface(), "not an interface");
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  assert(ctxk->implementor() == uniqk, "not a unique implementor");
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  assert_common_2(unique_implementor, DepValue(_oop_recorder, ctxk), DepValue(_oop_recorder, uniqk));
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}
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void Dependencies::assert_unique_concrete_method(Klass* ctxk, Method* uniqm) {
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  check_ctxk(ctxk);
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  check_unique_method(ctxk, uniqm);
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  assert_common_2(unique_concrete_method_2, DepValue(_oop_recorder, ctxk), DepValue(_oop_recorder, uniqm));
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}
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void Dependencies::assert_call_site_target_value(oop call_site, oop method_handle) {
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  assert_common_2(call_site_target_value, DepValue(_oop_recorder, JNIHandles::make_local(call_site)), DepValue(_oop_recorder, JNIHandles::make_local(method_handle)));
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}
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#endif // INCLUDE_JVMCI
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// Helper function.  If we are adding a new dep. under ctxk2,
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// try to find an old dep. under a broader* ctxk1.  If there is
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//
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bool Dependencies::maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps,
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                                    int ctxk_i, ciKlass* ctxk2) {
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  ciKlass* ctxk1 = deps->at(ctxk_i)->as_metadata()->as_klass();
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  if (ctxk2->is_subtype_of(ctxk1)) {
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    return true;  // success, and no need to change
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  } else if (ctxk1->is_subtype_of(ctxk2)) {
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    // new context class fully subsumes previous one
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    deps->at_put(ctxk_i, ctxk2);
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    return true;
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  } else {
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    return false;
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  }
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}
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void Dependencies::assert_common_1(DepType dept, ciBaseObject* x) {
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  assert(dep_args(dept) == 1, "sanity");
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  log_dependency(dept, x);
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  GrowableArray<ciBaseObject*>* deps = _deps[dept];
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  // see if the same (or a similar) dep is already recorded
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  if (note_dep_seen(dept, x)) {
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    assert(deps->find(x) >= 0, "sanity");
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  } else {
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    deps->append(x);
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  }
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}
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void Dependencies::assert_common_2(DepType dept,
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                                   ciBaseObject* x0, ciBaseObject* x1) {
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  assert(dep_args(dept) == 2, "sanity");
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  log_dependency(dept, x0, x1);
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  GrowableArray<ciBaseObject*>* deps = _deps[dept];
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  // see if the same (or a similar) dep is already recorded
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  bool has_ctxk = has_explicit_context_arg(dept);
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  if (has_ctxk) {
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    assert(dep_context_arg(dept) == 0, "sanity");
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    if (note_dep_seen(dept, x1)) {
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      // look in this bucket for redundant assertions
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      const int stride = 2;
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      for (int i = deps->length(); (i -= stride) >= 0; ) {
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        ciBaseObject* y1 = deps->at(i+1);
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        if (x1 == y1) {  // same subject; check the context
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          if (maybe_merge_ctxk(deps, i+0, x0->as_metadata()->as_klass())) {
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            return;
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          }
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        }
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      }
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    }
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  } else {
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    bool dep_seen_x0 = note_dep_seen(dept, x0); // records x0 for future queries
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    bool dep_seen_x1 = note_dep_seen(dept, x1); // records x1 for future queries
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    if (dep_seen_x0 && dep_seen_x1) {
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      // look in this bucket for redundant assertions
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      const int stride = 2;
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      for (int i = deps->length(); (i -= stride) >= 0; ) {
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        ciBaseObject* y0 = deps->at(i+0);
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        ciBaseObject* y1 = deps->at(i+1);
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        if (x0 == y0 && x1 == y1) {
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          return;
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        }
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      }
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    }
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  }
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  // append the assertion in the correct bucket:
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  deps->append(x0);
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  deps->append(x1);
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}
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void Dependencies::assert_common_4(DepType dept,
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                                   ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* x2, ciBaseObject* x3) {
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  assert(has_explicit_context_arg(dept), "sanity");
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  assert(dep_context_arg(dept) == 0, "sanity");
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  assert(dep_args(dept) == 4, "sanity");
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  log_dependency(dept, ctxk, x1, x2, x3);
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  GrowableArray<ciBaseObject*>* deps = _deps[dept];
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  // see if the same (or a similar) dep is already recorded
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  bool dep_seen_x1 = note_dep_seen(dept, x1); // records x1 for future queries
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  bool dep_seen_x2 = note_dep_seen(dept, x2); // records x2 for future queries
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  bool dep_seen_x3 = note_dep_seen(dept, x3); // records x3 for future queries
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  if (dep_seen_x1 && dep_seen_x2 && dep_seen_x3) {
288
    // look in this bucket for redundant assertions
289
    const int stride = 4;
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    for (int i = deps->length(); (i -= stride) >= 0; ) {
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      ciBaseObject* y1 = deps->at(i+1);
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      ciBaseObject* y2 = deps->at(i+2);
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      ciBaseObject* y3 = deps->at(i+3);
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      if (x1 == y1 && x2 == y2 && x3 == y3) {  // same subjects; check the context
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        if (maybe_merge_ctxk(deps, i+0, ctxk)) {
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          return;
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        }
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      }
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    }
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  }
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  // append the assertion in the correct bucket:
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  deps->append(ctxk);
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  deps->append(x1);
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  deps->append(x2);
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  deps->append(x3);
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}
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#if INCLUDE_JVMCI
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bool Dependencies::maybe_merge_ctxk(GrowableArray<DepValue>* deps,
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                                    int ctxk_i, DepValue ctxk2_dv) {
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  Klass* ctxk1 = deps->at(ctxk_i).as_klass(_oop_recorder);
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  Klass* ctxk2 = ctxk2_dv.as_klass(_oop_recorder);
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  if (ctxk2->is_subtype_of(ctxk1)) {
314
    return true;  // success, and no need to change
315
  } else if (ctxk1->is_subtype_of(ctxk2)) {
316
    // new context class fully subsumes previous one
317
    deps->at_put(ctxk_i, ctxk2_dv);
318
    return true;
319
  } else {
320
    return false;
321
  }
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}
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void Dependencies::assert_common_1(DepType dept, DepValue x) {
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  assert(dep_args(dept) == 1, "sanity");
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  //log_dependency(dept, x);
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  GrowableArray<DepValue>* deps = _dep_values[dept];
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  // see if the same (or a similar) dep is already recorded
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  if (note_dep_seen(dept, x)) {
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    assert(deps->find(x) >= 0, "sanity");
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  } else {
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    deps->append(x);
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  }
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}
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void Dependencies::assert_common_2(DepType dept,
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                                   DepValue x0, DepValue x1) {
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  assert(dep_args(dept) == 2, "sanity");
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  //log_dependency(dept, x0, x1);
341
  GrowableArray<DepValue>* deps = _dep_values[dept];
342

343
  // see if the same (or a similar) dep is already recorded
344
  bool has_ctxk = has_explicit_context_arg(dept);
345
  if (has_ctxk) {
346
    assert(dep_context_arg(dept) == 0, "sanity");
347
    if (note_dep_seen(dept, x1)) {
348
      // look in this bucket for redundant assertions
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      const int stride = 2;
350
      for (int i = deps->length(); (i -= stride) >= 0; ) {
351
        DepValue y1 = deps->at(i+1);
352
        if (x1 == y1) {  // same subject; check the context
353
          if (maybe_merge_ctxk(deps, i+0, x0)) {
354
            return;
355
          }
356
        }
357
      }
358
    }
359
  } else {
360
    bool dep_seen_x0 = note_dep_seen(dept, x0); // records x0 for future queries
361
    bool dep_seen_x1 = note_dep_seen(dept, x1); // records x1 for future queries
362
    if (dep_seen_x0 && dep_seen_x1) {
363
      // look in this bucket for redundant assertions
364
      const int stride = 2;
365
      for (int i = deps->length(); (i -= stride) >= 0; ) {
366
        DepValue y0 = deps->at(i+0);
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        DepValue y1 = deps->at(i+1);
368
        if (x0 == y0 && x1 == y1) {
369
          return;
370
        }
371
      }
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    }
373
  }
374

375
  // append the assertion in the correct bucket:
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  deps->append(x0);
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  deps->append(x1);
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}
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#endif // INCLUDE_JVMCI
380

381
/// Support for encoding dependencies into an nmethod:
382

383
void Dependencies::copy_to(nmethod* nm) {
384
  address beg = nm->dependencies_begin();
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  address end = nm->dependencies_end();
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  guarantee(end - beg >= (ptrdiff_t) size_in_bytes(), "bad sizing");
387
  (void)memcpy(beg, content_bytes(), size_in_bytes());
388
  assert(size_in_bytes() % sizeof(HeapWord) == 0, "copy by words");
389
}
390

391
static int sort_dep(ciBaseObject** p1, ciBaseObject** p2, int narg) {
392
  for (int i = 0; i < narg; i++) {
393
    int diff = p1[i]->ident() - p2[i]->ident();
394
    if (diff != 0)  return diff;
395
  }
396
  return 0;
397
}
398
static int sort_dep_arg_1(ciBaseObject** p1, ciBaseObject** p2)
399
{ return sort_dep(p1, p2, 1); }
400
static int sort_dep_arg_2(ciBaseObject** p1, ciBaseObject** p2)
401
{ return sort_dep(p1, p2, 2); }
402
static int sort_dep_arg_3(ciBaseObject** p1, ciBaseObject** p2)
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{ return sort_dep(p1, p2, 3); }
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static int sort_dep_arg_4(ciBaseObject** p1, ciBaseObject** p2)
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{ return sort_dep(p1, p2, 4); }
406

407
#if INCLUDE_JVMCI
408
// metadata deps are sorted before object deps
409
static int sort_dep_value(Dependencies::DepValue* p1, Dependencies::DepValue* p2, int narg) {
410
  for (int i = 0; i < narg; i++) {
411
    int diff = p1[i].sort_key() - p2[i].sort_key();
412
    if (diff != 0)  return diff;
413
  }
414
  return 0;
415
}
416
static int sort_dep_value_arg_1(Dependencies::DepValue* p1, Dependencies::DepValue* p2)
417
{ return sort_dep_value(p1, p2, 1); }
418
static int sort_dep_value_arg_2(Dependencies::DepValue* p1, Dependencies::DepValue* p2)
419
{ return sort_dep_value(p1, p2, 2); }
420
static int sort_dep_value_arg_3(Dependencies::DepValue* p1, Dependencies::DepValue* p2)
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{ return sort_dep_value(p1, p2, 3); }
422
#endif // INCLUDE_JVMCI
423

424
void Dependencies::sort_all_deps() {
425
#if INCLUDE_JVMCI
426
  if (_using_dep_values) {
427
    for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
428
      DepType dept = (DepType)deptv;
429
      GrowableArray<DepValue>* deps = _dep_values[dept];
430
      if (deps->length() <= 1)  continue;
431
      switch (dep_args(dept)) {
432
      case 1: deps->sort(sort_dep_value_arg_1, 1); break;
433
      case 2: deps->sort(sort_dep_value_arg_2, 2); break;
434
      case 3: deps->sort(sort_dep_value_arg_3, 3); break;
435
      default: ShouldNotReachHere(); break;
436
      }
437
    }
438
    return;
439
  }
440
#endif // INCLUDE_JVMCI
441
  for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
442
    DepType dept = (DepType)deptv;
443
    GrowableArray<ciBaseObject*>* deps = _deps[dept];
444
    if (deps->length() <= 1)  continue;
445
    switch (dep_args(dept)) {
446
    case 1: deps->sort(sort_dep_arg_1, 1); break;
447
    case 2: deps->sort(sort_dep_arg_2, 2); break;
448
    case 3: deps->sort(sort_dep_arg_3, 3); break;
449
    case 4: deps->sort(sort_dep_arg_4, 4); break;
450
    default: ShouldNotReachHere(); break;
451
    }
452
  }
453
}
454

455
size_t Dependencies::estimate_size_in_bytes() {
456
  size_t est_size = 100;
457
#if INCLUDE_JVMCI
458
  if (_using_dep_values) {
459
    for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
460
      DepType dept = (DepType)deptv;
461
      GrowableArray<DepValue>* deps = _dep_values[dept];
462
      est_size += deps->length() * 2;  // tags and argument(s)
463
    }
464
    return est_size;
465
  }
466
#endif // INCLUDE_JVMCI
467
  for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
468
    DepType dept = (DepType)deptv;
469
    GrowableArray<ciBaseObject*>* deps = _deps[dept];
470
    est_size += deps->length()*2;  // tags and argument(s)
471
  }
472
  return est_size;
473
}
474

475
ciKlass* Dependencies::ctxk_encoded_as_null(DepType dept, ciBaseObject* x) {
476
  switch (dept) {
477
  case unique_concrete_method_2:
478
  case unique_concrete_method_4:
479
    return x->as_metadata()->as_method()->holder();
480
  default:
481
    return nullptr;  // let nullptr be nullptr
482
  }
483
}
484

485
Klass* Dependencies::ctxk_encoded_as_null(DepType dept, Metadata* x) {
486
  assert(must_be_in_vm(), "raw oops here");
487
  switch (dept) {
488
  case unique_concrete_method_2:
489
  case unique_concrete_method_4:
490
    assert(x->is_method(), "sanity");
491
    return ((Method*)x)->method_holder();
492
  default:
493
    return nullptr;  // let nullptr be nullptr
494
  }
495
}
496

497
void Dependencies::encode_content_bytes() {
498
  sort_all_deps();
499

500
  // cast is safe, no deps can overflow INT_MAX
501
  CompressedWriteStream bytes((int)estimate_size_in_bytes());
502

503
#if INCLUDE_JVMCI
504
  if (_using_dep_values) {
505
    for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
506
      DepType dept = (DepType)deptv;
507
      GrowableArray<DepValue>* deps = _dep_values[dept];
508
      if (deps->length() == 0)  continue;
509
      int stride = dep_args(dept);
510
      int ctxkj  = dep_context_arg(dept);  // -1 if no context arg
511
      assert(stride > 0, "sanity");
512
      for (int i = 0; i < deps->length(); i += stride) {
513
        jbyte code_byte = (jbyte)dept;
514
        int skipj = -1;
515
        if (ctxkj >= 0 && ctxkj+1 < stride) {
516
          Klass*  ctxk = deps->at(i+ctxkj+0).as_klass(_oop_recorder);
517
          DepValue x = deps->at(i+ctxkj+1);  // following argument
518
          if (ctxk == ctxk_encoded_as_null(dept, x.as_metadata(_oop_recorder))) {
519
            skipj = ctxkj;  // we win:  maybe one less oop to keep track of
520
            code_byte |= default_context_type_bit;
521
          }
522
        }
523
        bytes.write_byte(code_byte);
524
        for (int j = 0; j < stride; j++) {
525
          if (j == skipj)  continue;
526
          DepValue v = deps->at(i+j);
527
          int idx = v.index();
528
          bytes.write_int(idx);
529
        }
530
      }
531
    }
532
  } else {
533
#endif // INCLUDE_JVMCI
534
  for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
535
    DepType dept = (DepType)deptv;
536
    GrowableArray<ciBaseObject*>* deps = _deps[dept];
537
    if (deps->length() == 0)  continue;
538
    int stride = dep_args(dept);
539
    int ctxkj  = dep_context_arg(dept);  // -1 if no context arg
540
    assert(stride > 0, "sanity");
541
    for (int i = 0; i < deps->length(); i += stride) {
542
      jbyte code_byte = (jbyte)dept;
543
      int skipj = -1;
544
      if (ctxkj >= 0 && ctxkj+1 < stride) {
545
        ciKlass*  ctxk = deps->at(i+ctxkj+0)->as_metadata()->as_klass();
546
        ciBaseObject* x     = deps->at(i+ctxkj+1);  // following argument
547
        if (ctxk == ctxk_encoded_as_null(dept, x)) {
548
          skipj = ctxkj;  // we win:  maybe one less oop to keep track of
549
          code_byte |= default_context_type_bit;
550
        }
551
      }
552
      bytes.write_byte(code_byte);
553
      for (int j = 0; j < stride; j++) {
554
        if (j == skipj)  continue;
555
        ciBaseObject* v = deps->at(i+j);
556
        int idx;
557
        if (v->is_object()) {
558
          idx = _oop_recorder->find_index(v->as_object()->constant_encoding());
559
        } else {
560
          ciMetadata* meta = v->as_metadata();
561
          idx = _oop_recorder->find_index(meta->constant_encoding());
562
        }
563
        bytes.write_int(idx);
564
      }
565
    }
566
  }
567
#if INCLUDE_JVMCI
568
  }
569
#endif
570

571
  // write a sentinel byte to mark the end
572
  bytes.write_byte(end_marker);
573

574
  // round it out to a word boundary
575
  while (bytes.position() % sizeof(HeapWord) != 0) {
576
    bytes.write_byte(end_marker);
577
  }
578

579
  // check whether the dept byte encoding really works
580
  assert((jbyte)default_context_type_bit != 0, "byte overflow");
581

582
  _content_bytes = bytes.buffer();
583
  _size_in_bytes = bytes.position();
584
}
585

586

587
const char* Dependencies::_dep_name[TYPE_LIMIT] = {
588
  "end_marker",
589
  "evol_method",
590
  "leaf_type",
591
  "abstract_with_unique_concrete_subtype",
592
  "unique_concrete_method_2",
593
  "unique_concrete_method_4",
594
  "unique_implementor",
595
  "no_finalizable_subclasses",
596
  "call_site_target_value"
597
};
598

599
int Dependencies::_dep_args[TYPE_LIMIT] = {
600
  -1,// end_marker
601
  1, // evol_method m
602
  1, // leaf_type ctxk
603
  2, // abstract_with_unique_concrete_subtype ctxk, k
604
  2, // unique_concrete_method_2 ctxk, m
605
  4, // unique_concrete_method_4 ctxk, m, resolved_klass, resolved_method
606
  2, // unique_implementor ctxk, implementor
607
  1, // no_finalizable_subclasses ctxk
608
  2  // call_site_target_value call_site, method_handle
609
};
610

611
const char* Dependencies::dep_name(Dependencies::DepType dept) {
612
  if (!dept_in_mask(dept, all_types))  return "?bad-dep?";
613
  return _dep_name[dept];
614
}
615

616
int Dependencies::dep_args(Dependencies::DepType dept) {
617
  if (!dept_in_mask(dept, all_types))  return -1;
618
  return _dep_args[dept];
619
}
620

621
void Dependencies::check_valid_dependency_type(DepType dept) {
622
  guarantee(FIRST_TYPE <= dept && dept < TYPE_LIMIT, "invalid dependency type: %d", (int) dept);
623
}
624

625
Dependencies::DepType Dependencies::validate_dependencies(CompileTask* task, char** failure_detail) {
626
  int klass_violations = 0;
627
  DepType result = end_marker;
628
  for (Dependencies::DepStream deps(this); deps.next(); ) {
629
    Klass* witness = deps.check_dependency();
630
    if (witness != nullptr) {
631
      if (klass_violations == 0) {
632
        result = deps.type();
633
        if (failure_detail != nullptr && klass_violations == 0) {
634
          // Use a fixed size buffer to prevent the string stream from
635
          // resizing in the context of an inner resource mark.
636
          char* buffer = NEW_RESOURCE_ARRAY(char, O_BUFLEN);
637
          stringStream st(buffer, O_BUFLEN);
638
          deps.print_dependency(&st, witness, true);
639
          *failure_detail = st.as_string();
640
        }
641
      }
642
      klass_violations++;
643
      if (xtty == nullptr) {
644
        // If we're not logging then a single violation is sufficient,
645
        // otherwise we want to log all the dependences which were
646
        // violated.
647
        break;
648
      }
649
    }
650
  }
651

652
  return result;
653
}
654

655
// for the sake of the compiler log, print out current dependencies:
656
void Dependencies::log_all_dependencies() {
657
  if (log() == nullptr)  return;
658
  ResourceMark rm;
659
  for (int deptv = (int)FIRST_TYPE; deptv < (int)TYPE_LIMIT; deptv++) {
660
    DepType dept = (DepType)deptv;
661
    GrowableArray<ciBaseObject*>* deps = _deps[dept];
662
    int deplen = deps->length();
663
    if (deplen == 0) {
664
      continue;
665
    }
666
    int stride = dep_args(dept);
667
    GrowableArray<ciBaseObject*>* ciargs = new GrowableArray<ciBaseObject*>(stride);
668
    for (int i = 0; i < deps->length(); i += stride) {
669
      for (int j = 0; j < stride; j++) {
670
        // flush out the identities before printing
671
        ciargs->push(deps->at(i+j));
672
      }
673
      write_dependency_to(log(), dept, ciargs);
674
      ciargs->clear();
675
    }
676
    guarantee(deplen == deps->length(), "deps array cannot grow inside nested ResoureMark scope");
677
  }
678
}
679

680
void Dependencies::write_dependency_to(CompileLog* log,
681
                                       DepType dept,
682
                                       GrowableArray<DepArgument>* args,
683
                                       Klass* witness) {
684
  if (log == nullptr) {
685
    return;
686
  }
687
  ResourceMark rm;
688
  ciEnv* env = ciEnv::current();
689
  GrowableArray<ciBaseObject*>* ciargs = new GrowableArray<ciBaseObject*>(args->length());
690
  for (GrowableArrayIterator<DepArgument> it = args->begin(); it != args->end(); ++it) {
691
    DepArgument arg = *it;
692
    if (arg.is_oop()) {
693
      ciargs->push(env->get_object(arg.oop_value()));
694
    } else {
695
      ciargs->push(env->get_metadata(arg.metadata_value()));
696
    }
697
  }
698
  int argslen = ciargs->length();
699
  Dependencies::write_dependency_to(log, dept, ciargs, witness);
700
  guarantee(argslen == ciargs->length(), "ciargs array cannot grow inside nested ResoureMark scope");
701
}
702

703
void Dependencies::write_dependency_to(CompileLog* log,
704
                                       DepType dept,
705
                                       GrowableArray<ciBaseObject*>* args,
706
                                       Klass* witness) {
707
  if (log == nullptr) {
708
    return;
709
  }
710
  ResourceMark rm;
711
  GrowableArray<int>* argids = new GrowableArray<int>(args->length());
712
  for (GrowableArrayIterator<ciBaseObject*> it = args->begin(); it != args->end(); ++it) {
713
    ciBaseObject* obj = *it;
714
    if (obj->is_object()) {
715
      argids->push(log->identify(obj->as_object()));
716
    } else {
717
      argids->push(log->identify(obj->as_metadata()));
718
    }
719
  }
720
  if (witness != nullptr) {
721
    log->begin_elem("dependency_failed");
722
  } else {
723
    log->begin_elem("dependency");
724
  }
725
  log->print(" type='%s'", dep_name(dept));
726
  const int ctxkj = dep_context_arg(dept);  // -1 if no context arg
727
  if (ctxkj >= 0 && ctxkj < argids->length()) {
728
    log->print(" ctxk='%d'", argids->at(ctxkj));
729
  }
730
  // write remaining arguments, if any.
731
  for (int j = 0; j < argids->length(); j++) {
732
    if (j == ctxkj)  continue;  // already logged
733
    if (j == 1) {
734
      log->print(  " x='%d'",    argids->at(j));
735
    } else {
736
      log->print(" x%d='%d'", j, argids->at(j));
737
    }
738
  }
739
  if (witness != nullptr) {
740
    log->object("witness", witness);
741
    log->stamp();
742
  }
743
  log->end_elem();
744
}
745

746
void Dependencies::write_dependency_to(xmlStream* xtty,
747
                                       DepType dept,
748
                                       GrowableArray<DepArgument>* args,
749
                                       Klass* witness) {
750
  if (xtty == nullptr) {
751
    return;
752
  }
753
  Thread* thread = Thread::current();
754
  HandleMark rm(thread);
755
  ttyLocker ttyl;
756
  int ctxkj = dep_context_arg(dept);  // -1 if no context arg
757
  if (witness != nullptr) {
758
    xtty->begin_elem("dependency_failed");
759
  } else {
760
    xtty->begin_elem("dependency");
761
  }
762
  xtty->print(" type='%s'", dep_name(dept));
763
  if (ctxkj >= 0) {
764
    xtty->object("ctxk", args->at(ctxkj).metadata_value());
765
  }
766
  // write remaining arguments, if any.
767
  for (int j = 0; j < args->length(); j++) {
768
    if (j == ctxkj)  continue;  // already logged
769
    DepArgument arg = args->at(j);
770
    if (j == 1) {
771
      if (arg.is_oop()) {
772
        xtty->object("x", Handle(thread, arg.oop_value()));
773
      } else {
774
        xtty->object("x", arg.metadata_value());
775
      }
776
    } else {
777
      char xn[12];
778
      os::snprintf_checked(xn, sizeof(xn), "x%d", j);
779
      if (arg.is_oop()) {
780
        xtty->object(xn, Handle(thread, arg.oop_value()));
781
      } else {
782
        xtty->object(xn, arg.metadata_value());
783
      }
784
    }
785
  }
786
  if (witness != nullptr) {
787
    xtty->object("witness", witness);
788
    xtty->stamp();
789
  }
790
  xtty->end_elem();
791
}
792

793
void Dependencies::print_dependency(DepType dept, GrowableArray<DepArgument>* args,
794
                                    Klass* witness, outputStream* st) {
795
  ResourceMark rm;
796
  ttyLocker ttyl;   // keep the following output all in one block
797
  st->print_cr("%s of type %s",
798
                (witness == nullptr)? "Dependency": "Failed dependency",
799
                dep_name(dept));
800
  // print arguments
801
  int ctxkj = dep_context_arg(dept);  // -1 if no context arg
802
  for (int j = 0; j < args->length(); j++) {
803
    DepArgument arg = args->at(j);
804
    bool put_star = false;
805
    if (arg.is_null())  continue;
806
    const char* what;
807
    if (j == ctxkj) {
808
      assert(arg.is_metadata(), "must be");
809
      what = "context";
810
      put_star = !Dependencies::is_concrete_klass((Klass*)arg.metadata_value());
811
    } else if (arg.is_method()) {
812
      what = "method ";
813
      put_star = !Dependencies::is_concrete_method((Method*)arg.metadata_value(), nullptr);
814
    } else if (arg.is_klass()) {
815
      what = "class  ";
816
    } else {
817
      what = "object ";
818
    }
819
    st->print("  %s = %s", what, (put_star? "*": ""));
820
    if (arg.is_klass()) {
821
      st->print("%s", ((Klass*)arg.metadata_value())->external_name());
822
    } else if (arg.is_method()) {
823
      ((Method*)arg.metadata_value())->print_value_on(st);
824
    } else if (arg.is_oop()) {
825
      arg.oop_value()->print_value_on(st);
826
    } else {
827
      ShouldNotReachHere(); // Provide impl for this type.
828
    }
829

830
    st->cr();
831
  }
832
  if (witness != nullptr) {
833
    bool put_star = !Dependencies::is_concrete_klass(witness);
834
    st->print_cr("  witness = %s%s",
835
                  (put_star? "*": ""),
836
                  witness->external_name());
837
  }
838
}
839

840
void Dependencies::DepStream::log_dependency(Klass* witness) {
841
  if (_deps == nullptr && xtty == nullptr)  return;  // fast cutout for runtime
842
  ResourceMark rm;
843
  const int nargs = argument_count();
844
  GrowableArray<DepArgument>* args = new GrowableArray<DepArgument>(nargs);
845
  for (int j = 0; j < nargs; j++) {
846
    if (is_oop_argument(j)) {
847
      args->push(argument_oop(j));
848
    } else {
849
      args->push(argument(j));
850
    }
851
  }
852
  int argslen = args->length();
853
  if (_deps != nullptr && _deps->log() != nullptr) {
854
    if (ciEnv::current() != nullptr) {
855
      Dependencies::write_dependency_to(_deps->log(), type(), args, witness);
856
    } else {
857
      // Treat the CompileLog as an xmlstream instead
858
      Dependencies::write_dependency_to((xmlStream*)_deps->log(), type(), args, witness);
859
    }
860
  } else {
861
    Dependencies::write_dependency_to(xtty, type(), args, witness);
862
  }
863
  guarantee(argslen == args->length(), "args array cannot grow inside nested ResoureMark scope");
864
}
865

866
void Dependencies::DepStream::print_dependency(outputStream* st, Klass* witness, bool verbose) {
867
  ResourceMark rm;
868
  int nargs = argument_count();
869
  GrowableArray<DepArgument>* args = new GrowableArray<DepArgument>(nargs);
870
  for (int j = 0; j < nargs; j++) {
871
    if (is_oop_argument(j)) {
872
      args->push(argument_oop(j));
873
    } else {
874
      args->push(argument(j));
875
    }
876
  }
877
  int argslen = args->length();
878
  Dependencies::print_dependency(type(), args, witness, st);
879
  if (verbose) {
880
    if (_code != nullptr) {
881
      st->print("  code: ");
882
      _code->print_value_on(st);
883
      st->cr();
884
    }
885
  }
886
  guarantee(argslen == args->length(), "args array cannot grow inside nested ResoureMark scope");
887
}
888

889

890
/// Dependency stream support (decodes dependencies from an nmethod):
891

892
#ifdef ASSERT
893
void Dependencies::DepStream::initial_asserts(size_t byte_limit) {
894
  assert(must_be_in_vm(), "raw oops here");
895
  _byte_limit = byte_limit;
896
  _type       = (DepType)(end_marker-1);  // defeat "already at end" assert
897
  assert((_code!=nullptr) + (_deps!=nullptr) == 1, "one or t'other");
898
}
899
#endif //ASSERT
900

901
bool Dependencies::DepStream::next() {
902
  assert(_type != end_marker, "already at end");
903
  if (_bytes.position() == 0 && _code != nullptr
904
      && _code->dependencies_size() == 0) {
905
    // Method has no dependencies at all.
906
    return false;
907
  }
908
  int code_byte = (_bytes.read_byte() & 0xFF);
909
  if (code_byte == end_marker) {
910
    DEBUG_ONLY(_type = end_marker);
911
    return false;
912
  } else {
913
    int ctxk_bit = (code_byte & Dependencies::default_context_type_bit);
914
    code_byte -= ctxk_bit;
915
    DepType dept = (DepType)code_byte;
916
    _type = dept;
917
    Dependencies::check_valid_dependency_type(dept);
918
    int stride = _dep_args[dept];
919
    assert(stride == dep_args(dept), "sanity");
920
    int skipj = -1;
921
    if (ctxk_bit != 0) {
922
      skipj = 0;  // currently the only context argument is at zero
923
      assert(skipj == dep_context_arg(dept), "zero arg always ctxk");
924
    }
925
    for (int j = 0; j < stride; j++) {
926
      _xi[j] = (j == skipj)? 0: _bytes.read_int();
927
    }
928
    DEBUG_ONLY(_xi[stride] = -1);   // help detect overruns
929
    return true;
930
  }
931
}
932

933
inline Metadata* Dependencies::DepStream::recorded_metadata_at(int i) {
934
  Metadata* o = nullptr;
935
  if (_code != nullptr) {
936
    o = _code->metadata_at(i);
937
  } else {
938
    o = _deps->oop_recorder()->metadata_at(i);
939
  }
940
  return o;
941
}
942

943
inline oop Dependencies::DepStream::recorded_oop_at(int i) {
944
  return (_code != nullptr)
945
         ? _code->oop_at(i)
946
    : JNIHandles::resolve(_deps->oop_recorder()->oop_at(i));
947
}
948

949
Metadata* Dependencies::DepStream::argument(int i) {
950
  Metadata* result = recorded_metadata_at(argument_index(i));
951

952
  if (result == nullptr) { // Explicit context argument can be compressed
953
    int ctxkj = dep_context_arg(type());  // -1 if no explicit context arg
954
    if (ctxkj >= 0 && i == ctxkj && ctxkj+1 < argument_count()) {
955
      result = ctxk_encoded_as_null(type(), argument(ctxkj+1));
956
    }
957
  }
958

959
  assert(result == nullptr || result->is_klass() || result->is_method(), "must be");
960
  return result;
961
}
962

963
/**
964
 * Returns a unique identifier for each dependency argument.
965
 */
966
uintptr_t Dependencies::DepStream::get_identifier(int i) {
967
  if (is_oop_argument(i)) {
968
    return (uintptr_t)(oopDesc*)argument_oop(i);
969
  } else {
970
    return (uintptr_t)argument(i);
971
  }
972
}
973

974
oop Dependencies::DepStream::argument_oop(int i) {
975
  oop result = recorded_oop_at(argument_index(i));
976
  assert(oopDesc::is_oop_or_null(result), "must be");
977
  return result;
978
}
979

980
InstanceKlass* Dependencies::DepStream::context_type() {
981
  assert(must_be_in_vm(), "raw oops here");
982

983
  // Most dependencies have an explicit context type argument.
984
  {
985
    int ctxkj = dep_context_arg(type());  // -1 if no explicit context arg
986
    if (ctxkj >= 0) {
987
      Metadata* k = argument(ctxkj);
988
      assert(k != nullptr && k->is_klass(), "type check");
989
      return InstanceKlass::cast((Klass*)k);
990
    }
991
  }
992

993
  // Some dependencies are using the klass of the first object
994
  // argument as implicit context type.
995
  {
996
    int ctxkj = dep_implicit_context_arg(type());
997
    if (ctxkj >= 0) {
998
      Klass* k = argument_oop(ctxkj)->klass();
999
      assert(k != nullptr, "type check");
1000
      return InstanceKlass::cast(k);
1001
    }
1002
  }
1003

1004
  // And some dependencies don't have a context type at all,
1005
  // e.g. evol_method.
1006
  return nullptr;
1007
}
1008

1009
// ----------------- DependencySignature --------------------------------------
1010
bool DependencySignature::equals(DependencySignature const& s1, DependencySignature const& s2) {
1011
  if ((s1.type() != s2.type()) || (s1.args_count() != s2.args_count())) {
1012
    return false;
1013
  }
1014

1015
  for (int i = 0; i < s1.args_count(); i++) {
1016
    if (s1.arg(i) != s2.arg(i)) {
1017
      return false;
1018
    }
1019
  }
1020
  return true;
1021
}
1022

1023
/// Checking dependencies
1024

1025
// This hierarchy walker inspects subtypes of a given type, trying to find a "bad" class which breaks a dependency.
1026
// Such a class is called a "witness" to the broken dependency.
1027
// While searching around, we ignore "participants", which are already known to the dependency.
1028
class AbstractClassHierarchyWalker {
1029
 public:
1030
  enum { PARTICIPANT_LIMIT = 3 };
1031

1032
 private:
1033
  // if non-zero, tells how many witnesses to convert to participants
1034
  uint _record_witnesses;
1035

1036
  // special classes which are not allowed to be witnesses:
1037
  Klass* _participants[PARTICIPANT_LIMIT+1];
1038
  uint   _num_participants;
1039

1040
#ifdef ASSERT
1041
  uint _nof_requests; // one-shot walker
1042
#endif // ASSERT
1043

1044
  static PerfCounter* _perf_find_witness_anywhere_calls_count;
1045
  static PerfCounter* _perf_find_witness_anywhere_steps_count;
1046
  static PerfCounter* _perf_find_witness_in_calls_count;
1047

1048
 protected:
1049
  virtual Klass* find_witness_in(KlassDepChange& changes) = 0;
1050
  virtual Klass* find_witness_anywhere(InstanceKlass* context_type) = 0;
1051

1052
  AbstractClassHierarchyWalker(Klass* participant) : _record_witnesses(0), _num_participants(0)
1053
#ifdef ASSERT
1054
  , _nof_requests(0)
1055
#endif // ASSERT
1056
  {
1057
    for (uint i = 0; i < PARTICIPANT_LIMIT+1; i++) {
1058
      _participants[i] = nullptr;
1059
    }
1060
    if (participant != nullptr) {
1061
      add_participant(participant);
1062
    }
1063
  }
1064

1065
  bool is_participant(Klass* k) {
1066
    for (uint i = 0; i < _num_participants; i++) {
1067
      if (_participants[i] == k) {
1068
        return true;
1069
      }
1070
    }
1071
    return false;
1072
  }
1073

1074
  bool record_witness(Klass* witness) {
1075
    if (_record_witnesses > 0) {
1076
      --_record_witnesses;
1077
      add_participant(witness);
1078
      return false; // not a witness
1079
    } else {
1080
      return true; // is a witness
1081
    }
1082
  }
1083

1084
  class CountingClassHierarchyIterator : public ClassHierarchyIterator {
1085
   private:
1086
    jlong _nof_steps;
1087
   public:
1088
    CountingClassHierarchyIterator(InstanceKlass* root) : ClassHierarchyIterator(root), _nof_steps(0) {}
1089

1090
    void next() {
1091
      _nof_steps++;
1092
      ClassHierarchyIterator::next();
1093
    }
1094

1095
    ~CountingClassHierarchyIterator() {
1096
      if (UsePerfData) {
1097
        _perf_find_witness_anywhere_steps_count->inc(_nof_steps);
1098
      }
1099
    }
1100
  };
1101

1102
 public:
1103
  uint num_participants() { return _num_participants; }
1104
  Klass* participant(uint n) {
1105
    assert(n <= _num_participants, "oob");
1106
    if (n < _num_participants) {
1107
      return _participants[n];
1108
    } else {
1109
      return nullptr;
1110
    }
1111
  }
1112

1113
  void add_participant(Klass* participant) {
1114
    assert(!is_participant(participant), "sanity");
1115
    assert(_num_participants + _record_witnesses < PARTICIPANT_LIMIT, "oob");
1116
    uint np = _num_participants++;
1117
    _participants[np] = participant;
1118
  }
1119

1120
  void record_witnesses(uint add) {
1121
    if (add > PARTICIPANT_LIMIT)  add = PARTICIPANT_LIMIT;
1122
    assert(_num_participants + add < PARTICIPANT_LIMIT, "oob");
1123
    _record_witnesses = add;
1124
  }
1125

1126
  Klass* find_witness(InstanceKlass* context_type, KlassDepChange* changes = nullptr);
1127

1128
  static void init();
1129
  static void print_statistics();
1130
};
1131

1132
PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_anywhere_calls_count = nullptr;
1133
PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_anywhere_steps_count = nullptr;
1134
PerfCounter* AbstractClassHierarchyWalker::_perf_find_witness_in_calls_count       = nullptr;
1135

1136
void AbstractClassHierarchyWalker::init() {
1137
  if (UsePerfData) {
1138
    EXCEPTION_MARK;
1139
    _perf_find_witness_anywhere_calls_count =
1140
        PerfDataManager::create_counter(SUN_CI, "findWitnessAnywhere", PerfData::U_Events, CHECK);
1141
    _perf_find_witness_anywhere_steps_count =
1142
        PerfDataManager::create_counter(SUN_CI, "findWitnessAnywhereSteps", PerfData::U_Events, CHECK);
1143
    _perf_find_witness_in_calls_count =
1144
        PerfDataManager::create_counter(SUN_CI, "findWitnessIn", PerfData::U_Events, CHECK);
1145
  }
1146
}
1147

1148
Klass* AbstractClassHierarchyWalker::find_witness(InstanceKlass* context_type, KlassDepChange* changes) {
1149
  // Current thread must be in VM (not native mode, as in CI):
1150
  assert(must_be_in_vm(), "raw oops here");
1151
  // Must not move the class hierarchy during this check:
1152
  assert_locked_or_safepoint(Compile_lock);
1153
  assert(_nof_requests++ == 0, "repeated requests are not supported");
1154

1155
  assert(changes == nullptr || changes->involves_context(context_type), "irrelevant dependency");
1156

1157
  // (Note: Interfaces do not have subclasses.)
1158
  // If it is an interface, search its direct implementors.
1159
  // (Their subclasses are additional indirect implementors. See InstanceKlass::add_implementor().)
1160
  if (context_type->is_interface()) {
1161
    int nof_impls = context_type->nof_implementors();
1162
    if (nof_impls == 0) {
1163
      return nullptr; // no implementors
1164
    } else if (nof_impls == 1) { // unique implementor
1165
      assert(context_type != context_type->implementor(), "not unique");
1166
      context_type = context_type->implementor();
1167
    } else { // nof_impls >= 2
1168
      // Avoid this case: *I.m > { A.m, C }; B.m > C
1169
      // Here, I.m has 2 concrete implementations, but m appears unique
1170
      // as A.m, because the search misses B.m when checking C.
1171
      // The inherited method B.m was getting missed by the walker
1172
      // when interface 'I' was the starting point.
1173
      // %%% Until this is fixed more systematically, bail out.
1174
      return context_type;
1175
    }
1176
  }
1177
  assert(!context_type->is_interface(), "no interfaces allowed");
1178

1179
  if (changes != nullptr) {
1180
    if (UsePerfData) {
1181
      _perf_find_witness_in_calls_count->inc();
1182
    }
1183
    return find_witness_in(*changes);
1184
  } else {
1185
    if (UsePerfData) {
1186
      _perf_find_witness_anywhere_calls_count->inc();
1187
    }
1188
    return find_witness_anywhere(context_type);
1189
  }
1190
}
1191

1192
class ConcreteSubtypeFinder : public AbstractClassHierarchyWalker {
1193
 private:
1194
  bool is_witness(Klass* k);
1195

1196
 protected:
1197
  virtual Klass* find_witness_in(KlassDepChange& changes);
1198
  virtual Klass* find_witness_anywhere(InstanceKlass* context_type);
1199

1200
 public:
1201
  ConcreteSubtypeFinder(Klass* participant = nullptr) : AbstractClassHierarchyWalker(participant) {}
1202
};
1203

1204
bool ConcreteSubtypeFinder::is_witness(Klass* k) {
1205
  if (Dependencies::is_concrete_klass(k)) {
1206
    return record_witness(k); // concrete subtype
1207
  } else {
1208
    return false; // not a concrete class
1209
  }
1210
}
1211

1212
Klass* ConcreteSubtypeFinder::find_witness_in(KlassDepChange& changes) {
1213
  // When looking for unexpected concrete types, do not look beneath expected ones:
1214
  //  * CX > CC > C' is OK, even if C' is new.
1215
  //  * CX > { CC,  C' } is not OK if C' is new, and C' is the witness.
1216
  Klass* new_type = changes.as_new_klass_change()->new_type();
1217
  assert(!is_participant(new_type), "only old classes are participants");
1218
  // If the new type is a subtype of a participant, we are done.
1219
  for (uint i = 0; i < num_participants(); i++) {
1220
    if (changes.involves_context(participant(i))) {
1221
      // new guy is protected from this check by previous participant
1222
      return nullptr;
1223
    }
1224
  }
1225
  if (is_witness(new_type)) {
1226
    return new_type;
1227
  }
1228
  // No witness found.  The dependency remains unbroken.
1229
  return nullptr;
1230
}
1231

1232
Klass* ConcreteSubtypeFinder::find_witness_anywhere(InstanceKlass* context_type) {
1233
  for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) {
1234
    Klass* sub = iter.klass();
1235
    // Do not report participant types.
1236
    if (is_participant(sub)) {
1237
      // Don't walk beneath a participant since it hides witnesses.
1238
      iter.skip_subclasses();
1239
    } else if (is_witness(sub)) {
1240
      return sub; // found a witness
1241
    }
1242
  }
1243
  // No witness found.  The dependency remains unbroken.
1244
  return nullptr;
1245
}
1246

1247
class ConcreteMethodFinder : public AbstractClassHierarchyWalker {
1248
 private:
1249
  Symbol* _name;
1250
  Symbol* _signature;
1251

1252
  // cache of method lookups
1253
  Method* _found_methods[PARTICIPANT_LIMIT+1];
1254

1255
  bool is_witness(Klass* k);
1256

1257
 protected:
1258
  virtual Klass* find_witness_in(KlassDepChange& changes);
1259
  virtual Klass* find_witness_anywhere(InstanceKlass* context_type);
1260

1261
 public:
1262
  bool witnessed_reabstraction_in_supers(Klass* k);
1263

1264
  ConcreteMethodFinder(Method* m, Klass* participant = nullptr) : AbstractClassHierarchyWalker(participant) {
1265
    assert(m != nullptr && m->is_method(), "sanity");
1266
    _name      = m->name();
1267
    _signature = m->signature();
1268

1269
    for (int i = 0; i < PARTICIPANT_LIMIT+1; i++) {
1270
      _found_methods[i] = nullptr;
1271
    }
1272
  }
1273

1274
  // Note:  If n==num_participants, returns nullptr.
1275
  Method* found_method(uint n) {
1276
    assert(n <= num_participants(), "oob");
1277
    Method* fm = _found_methods[n];
1278
    assert(n == num_participants() || fm != nullptr, "proper usage");
1279
    if (fm != nullptr && fm->method_holder() != participant(n)) {
1280
      // Default methods from interfaces can be added to classes. In
1281
      // that case the holder of the method is not the class but the
1282
      // interface where it's defined.
1283
      assert(fm->is_default_method(), "sanity");
1284
      return nullptr;
1285
    }
1286
    return fm;
1287
  }
1288

1289
  void add_participant(Klass* participant) {
1290
    AbstractClassHierarchyWalker::add_participant(participant);
1291
    _found_methods[num_participants()] = nullptr;
1292
  }
1293

1294
  bool record_witness(Klass* witness, Method* m) {
1295
    _found_methods[num_participants()] = m;
1296
    return AbstractClassHierarchyWalker::record_witness(witness);
1297
  }
1298

1299
 private:
1300
  static PerfCounter* _perf_find_witness_anywhere_calls_count;
1301
  static PerfCounter* _perf_find_witness_anywhere_steps_count;
1302
  static PerfCounter* _perf_find_witness_in_calls_count;
1303

1304
 public:
1305
  static void init();
1306
  static void print_statistics();
1307
};
1308

1309
bool ConcreteMethodFinder::is_witness(Klass* k) {
1310
  if (is_participant(k)) {
1311
    return false; // do not report participant types
1312
  }
1313
  if (k->is_instance_klass()) {
1314
    InstanceKlass* ik = InstanceKlass::cast(k);
1315
    // Search class hierarchy first, skipping private implementations
1316
    // as they never override any inherited methods
1317
    Method* m = ik->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1318
    if (Dependencies::is_concrete_method(m, ik)) {
1319
      return record_witness(k, m); // concrete method found
1320
    } else {
1321
      // Check for re-abstraction of method
1322
      if (!ik->is_interface() && m != nullptr && m->is_abstract()) {
1323
        // Found a matching abstract method 'm' in the class hierarchy.
1324
        // This is fine iff 'k' is an abstract class and all concrete subtypes
1325
        // of 'k' override 'm' and are participates of the current search.
1326
        ConcreteSubtypeFinder wf;
1327
        for (uint i = 0; i < num_participants(); i++) {
1328
          Klass* p = participant(i);
1329
          wf.add_participant(p);
1330
        }
1331
        Klass* w = wf.find_witness(ik);
1332
        if (w != nullptr) {
1333
          Method* wm = InstanceKlass::cast(w)->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1334
          if (!Dependencies::is_concrete_method(wm, w)) {
1335
            // Found a concrete subtype 'w' which does not override abstract method 'm'.
1336
            // Bail out because 'm' could be called with 'w' as receiver (leading to an
1337
            // AbstractMethodError) and thus the method we are looking for is not unique.
1338
            return record_witness(k, m);
1339
          }
1340
        }
1341
      }
1342
      // Check interface defaults also, if any exist.
1343
      Array<Method*>* default_methods = ik->default_methods();
1344
      if (default_methods != nullptr) {
1345
        Method* dm = ik->find_method(default_methods, _name, _signature);
1346
        if (Dependencies::is_concrete_method(dm, nullptr)) {
1347
          return record_witness(k, dm); // default method found
1348
        }
1349
      }
1350
      return false; // no concrete method found
1351
    }
1352
  } else {
1353
    return false; // no methods to find in an array type
1354
  }
1355
}
1356

1357
Klass* ConcreteMethodFinder::find_witness_in(KlassDepChange& changes) {
1358
  // When looking for unexpected concrete methods, look beneath expected ones, to see if there are overrides.
1359
  //  * CX.m > CC.m > C'.m is not OK, if C'.m is new, and C' is the witness.
1360
  Klass* new_type = changes.as_new_klass_change()->new_type();
1361
  assert(!is_participant(new_type), "only old classes are participants");
1362
  if (is_witness(new_type)) {
1363
    return new_type;
1364
  } else {
1365
    // No witness found, but is_witness() doesn't detect method re-abstraction in case of spot-checking.
1366
    if (witnessed_reabstraction_in_supers(new_type)) {
1367
      return new_type;
1368
    }
1369
  }
1370
  // No witness found.  The dependency remains unbroken.
1371
  return nullptr;
1372
}
1373

1374
bool ConcreteMethodFinder::witnessed_reabstraction_in_supers(Klass* k) {
1375
  if (!k->is_instance_klass()) {
1376
    return false; // no methods to find in an array type
1377
  } else {
1378
    // Looking for a case when an abstract method is inherited into a concrete class.
1379
    if (Dependencies::is_concrete_klass(k) && !k->is_interface()) {
1380
      Method* m = InstanceKlass::cast(k)->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1381
      if (m != nullptr) {
1382
        return false; // no reabstraction possible: local method found
1383
      }
1384
      for (InstanceKlass* super = k->java_super(); super != nullptr; super = super->java_super()) {
1385
        m = super->find_instance_method(_name, _signature, Klass::PrivateLookupMode::skip);
1386
        if (m != nullptr) { // inherited method found
1387
          if (m->is_abstract() || m->is_overpass()) {
1388
            return record_witness(super, m); // abstract method found
1389
          }
1390
          return false;
1391
        }
1392
      }
1393
      // Miranda.
1394
      return true;
1395
    }
1396
    return false;
1397
  }
1398
}
1399

1400

1401
Klass* ConcreteMethodFinder::find_witness_anywhere(InstanceKlass* context_type) {
1402
  // Walk hierarchy under a context type, looking for unexpected types.
1403
  for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) {
1404
    Klass* sub = iter.klass();
1405
    if (is_witness(sub)) {
1406
      return sub; // found a witness
1407
    }
1408
  }
1409
  // No witness found.  The dependency remains unbroken.
1410
  return nullptr;
1411
}
1412

1413
// For some method m and some class ctxk (subclass of method holder),
1414
// enumerate all distinct overrides of m in concrete subclasses of ctxk.
1415
// It relies on vtable/itable information to perform method selection on each linked subclass
1416
// and ignores all non yet linked ones (speculatively treat them as "effectively abstract").
1417
class LinkedConcreteMethodFinder : public AbstractClassHierarchyWalker {
1418
 private:
1419
  InstanceKlass* _resolved_klass;   // resolved class (JVMS-5.4.3.1)
1420
  InstanceKlass* _declaring_klass;  // the holder of resolved method (JVMS-5.4.3.3)
1421
  int            _vtable_index;     // vtable/itable index of the resolved method
1422
  bool           _do_itable_lookup; // choose between itable and vtable lookup logic
1423

1424
  // cache of method lookups
1425
  Method* _found_methods[PARTICIPANT_LIMIT+1];
1426

1427
  bool is_witness(Klass* k);
1428
  Method* select_method(InstanceKlass* recv_klass);
1429
  static int compute_vtable_index(InstanceKlass* resolved_klass, Method* resolved_method, bool& is_itable_index);
1430
  static bool is_concrete_klass(InstanceKlass* ik);
1431

1432
  void add_participant(Method* m, Klass* participant) {
1433
    uint np = num_participants();
1434
    AbstractClassHierarchyWalker::add_participant(participant);
1435
    assert(np + 1 == num_participants(), "sanity");
1436
    _found_methods[np] = m; // record the method for the participant
1437
  }
1438

1439
  bool record_witness(Klass* witness, Method* m) {
1440
    for (uint i = 0; i < num_participants(); i++) {
1441
      if (found_method(i) == m) {
1442
        return false; // already recorded
1443
      }
1444
    }
1445
    // Record not yet seen method.
1446
    _found_methods[num_participants()] = m;
1447
    return AbstractClassHierarchyWalker::record_witness(witness);
1448
  }
1449

1450
  void initialize(Method* participant) {
1451
    for (uint i = 0; i < PARTICIPANT_LIMIT+1; i++) {
1452
      _found_methods[i] = nullptr;
1453
    }
1454
    if (participant != nullptr) {
1455
      add_participant(participant, participant->method_holder());
1456
    }
1457
  }
1458

1459
 protected:
1460
  virtual Klass* find_witness_in(KlassDepChange& changes);
1461
  virtual Klass* find_witness_anywhere(InstanceKlass* context_type);
1462

1463
 public:
1464
  // In order to perform method selection, the following info is needed:
1465
  //  (1) interface or virtual call;
1466
  //  (2) vtable/itable index;
1467
  //  (3) declaring class (in case of interface call).
1468
  //
1469
  // It is prepared based on the results of method resolution: resolved class and resolved method (as specified in JVMS-5.4.3.3).
1470
  // Optionally, a method which was previously determined as a unique target (uniqm) is added as a participant
1471
  // to enable dependency spot-checking and speed up the search.
1472
  LinkedConcreteMethodFinder(InstanceKlass* resolved_klass, Method* resolved_method, Method* uniqm = nullptr) : AbstractClassHierarchyWalker(nullptr) {
1473
    assert(resolved_klass->is_linked(), "required");
1474
    assert(resolved_method->method_holder()->is_linked(), "required");
1475
    assert(!resolved_method->can_be_statically_bound(), "no vtable index available");
1476

1477
    _resolved_klass  = resolved_klass;
1478
    _declaring_klass = resolved_method->method_holder();
1479
    _vtable_index    = compute_vtable_index(resolved_klass, resolved_method,
1480
                                            _do_itable_lookup); // out parameter
1481
    assert(_vtable_index >= 0, "invalid vtable index");
1482

1483
    initialize(uniqm);
1484
  }
1485

1486
  // Note:  If n==num_participants, returns nullptr.
1487
  Method* found_method(uint n) {
1488
    assert(n <= num_participants(), "oob");
1489
    assert(participant(n) != nullptr || n == num_participants(), "proper usage");
1490
    return _found_methods[n];
1491
  }
1492
};
1493

1494
Klass* LinkedConcreteMethodFinder::find_witness_in(KlassDepChange& changes) {
1495
  Klass* type = changes.type();
1496

1497
  assert(!is_participant(type), "only old classes are participants");
1498

1499
  if (is_witness(type)) {
1500
    return type;
1501
  }
1502
  return nullptr; // No witness found.  The dependency remains unbroken.
1503
}
1504

1505
Klass* LinkedConcreteMethodFinder::find_witness_anywhere(InstanceKlass* context_type) {
1506
  for (CountingClassHierarchyIterator iter(context_type); !iter.done(); iter.next()) {
1507
    Klass* sub = iter.klass();
1508
    if (is_witness(sub)) {
1509
      return sub;
1510
    }
1511
    if (sub->is_instance_klass() && !InstanceKlass::cast(sub)->is_linked()) {
1512
      iter.skip_subclasses(); // ignore not yet linked classes
1513
    }
1514
  }
1515
  return nullptr; // No witness found. The dependency remains unbroken.
1516
}
1517

1518
bool LinkedConcreteMethodFinder::is_witness(Klass* k) {
1519
  if (is_participant(k)) {
1520
    return false; // do not report participant types
1521
  } else if (k->is_instance_klass()) {
1522
    InstanceKlass* ik = InstanceKlass::cast(k);
1523
    if (is_concrete_klass(ik)) {
1524
      Method* m = select_method(ik);
1525
      return record_witness(ik, m);
1526
    } else {
1527
      return false; // ignore non-concrete holder class
1528
    }
1529
  } else {
1530
    return false; // no methods to find in an array type
1531
  }
1532
}
1533

1534
Method* LinkedConcreteMethodFinder::select_method(InstanceKlass* recv_klass) {
1535
  Method* selected_method = nullptr;
1536
  if (_do_itable_lookup) {
1537
    assert(_declaring_klass->is_interface(), "sanity");
1538
    bool implements_interface; // initialized by method_at_itable_or_null()
1539
    selected_method = recv_klass->method_at_itable_or_null(_declaring_klass, _vtable_index,
1540
                                                           implements_interface); // out parameter
1541
    assert(implements_interface, "not implemented");
1542
  } else {
1543
    selected_method = recv_klass->method_at_vtable(_vtable_index);
1544
  }
1545
  return selected_method; // nullptr when corresponding slot is empty (AbstractMethodError case)
1546
}
1547

1548
int LinkedConcreteMethodFinder::compute_vtable_index(InstanceKlass* resolved_klass, Method* resolved_method,
1549
                                                     // out parameter
1550
                                                     bool& is_itable_index) {
1551
  if (resolved_klass->is_interface() && resolved_method->has_itable_index()) {
1552
    is_itable_index = true;
1553
    return resolved_method->itable_index();
1554
  }
1555
  // Check for default or miranda method first.
1556
  InstanceKlass* declaring_klass = resolved_method->method_holder();
1557
  if (!resolved_klass->is_interface() && declaring_klass->is_interface()) {
1558
    is_itable_index = false;
1559
    return resolved_klass->vtable_index_of_interface_method(resolved_method);
1560
  }
1561
  // At this point we are sure that resolved_method is virtual and not
1562
  // a default or miranda method; therefore, it must have a valid vtable index.
1563
  assert(resolved_method->has_vtable_index(), "");
1564
  is_itable_index = false;
1565
  return resolved_method->vtable_index();
1566
}
1567

1568
bool LinkedConcreteMethodFinder::is_concrete_klass(InstanceKlass* ik) {
1569
  if (!Dependencies::is_concrete_klass(ik)) {
1570
    return false; // not concrete
1571
  }
1572
  if (ik->is_interface()) {
1573
    return false; // interfaces aren't concrete
1574
  }
1575
  if (!ik->is_linked()) {
1576
    return false; // not yet linked classes don't have instances
1577
  }
1578
  return true;
1579
}
1580

1581
#ifdef ASSERT
1582
// Assert that m is inherited into ctxk, without intervening overrides.
1583
// (May return true even if this is not true, in corner cases where we punt.)
1584
bool Dependencies::verify_method_context(InstanceKlass* ctxk, Method* m) {
1585
  if (m->is_private()) {
1586
    return false; // Quick lose.  Should not happen.
1587
  }
1588
  if (m->method_holder() == ctxk) {
1589
    return true;  // Quick win.
1590
  }
1591
  if (!(m->is_public() || m->is_protected())) {
1592
    // The override story is complex when packages get involved.
1593
    return true;  // Must punt the assertion to true.
1594
  }
1595
  Method* lm = ctxk->lookup_method(m->name(), m->signature());
1596
  if (lm == nullptr) {
1597
    // It might be an interface method
1598
    lm = ctxk->lookup_method_in_ordered_interfaces(m->name(), m->signature());
1599
  }
1600
  if (lm == m) {
1601
    // Method m is inherited into ctxk.
1602
    return true;
1603
  }
1604
  if (lm != nullptr) {
1605
    if (!(lm->is_public() || lm->is_protected())) {
1606
      // Method is [package-]private, so the override story is complex.
1607
      return true;  // Must punt the assertion to true.
1608
    }
1609
    if (lm->is_static()) {
1610
      // Static methods don't override non-static so punt
1611
      return true;
1612
    }
1613
    if (!Dependencies::is_concrete_method(lm, ctxk) &&
1614
        !Dependencies::is_concrete_method(m, ctxk)) {
1615
      // They are both non-concrete
1616
      if (lm->method_holder()->is_subtype_of(m->method_holder())) {
1617
        // Method m is overridden by lm, but both are non-concrete.
1618
        return true;
1619
      }
1620
      if (lm->method_holder()->is_interface() && m->method_holder()->is_interface() &&
1621
          ctxk->is_subtype_of(m->method_holder()) && ctxk->is_subtype_of(lm->method_holder())) {
1622
        // Interface method defined in multiple super interfaces
1623
        return true;
1624
      }
1625
    }
1626
  }
1627
  ResourceMark rm;
1628
  tty->print_cr("Dependency method not found in the associated context:");
1629
  tty->print_cr("  context = %s", ctxk->external_name());
1630
  tty->print(   "  method = "); m->print_short_name(tty); tty->cr();
1631
  if (lm != nullptr) {
1632
    tty->print( "  found = "); lm->print_short_name(tty); tty->cr();
1633
  }
1634
  return false;
1635
}
1636
#endif // ASSERT
1637

1638
bool Dependencies::is_concrete_klass(Klass* k) {
1639
  if (k->is_abstract())  return false;
1640
  // %%% We could treat classes which are concrete but
1641
  // have not yet been instantiated as virtually abstract.
1642
  // This would require a deoptimization barrier on first instantiation.
1643
  //if (k->is_not_instantiated())  return false;
1644
  return true;
1645
}
1646

1647
bool Dependencies::is_concrete_method(Method* m, Klass* k) {
1648
  // nullptr is not a concrete method.
1649
  if (m == nullptr) {
1650
    return false;
1651
  }
1652
  // Statics are irrelevant to virtual call sites.
1653
  if (m->is_static()) {
1654
    return false;
1655
  }
1656
  // Abstract methods are not concrete.
1657
  if (m->is_abstract()) {
1658
    return false;
1659
  }
1660
  // Overpass (error) methods are not concrete if k is abstract.
1661
  if (m->is_overpass() && k != nullptr) {
1662
     return !k->is_abstract();
1663
  }
1664
  // Note "true" is conservative answer: overpass clause is false if k == nullptr,
1665
  // implies return true if answer depends on overpass clause.
1666
  return true;
1667
 }
1668

1669
Klass* Dependencies::find_finalizable_subclass(InstanceKlass* ik) {
1670
  for (ClassHierarchyIterator iter(ik); !iter.done(); iter.next()) {
1671
    Klass* sub = iter.klass();
1672
    if (sub->has_finalizer() && !sub->is_interface()) {
1673
      return sub;
1674
    }
1675
  }
1676
  return nullptr; // not found
1677
}
1678

1679
bool Dependencies::is_concrete_klass(ciInstanceKlass* k) {
1680
  if (k->is_abstract())  return false;
1681
  // We could also return false if k does not yet appear to be
1682
  // instantiated, if the VM version supports this distinction also.
1683
  //if (k->is_not_instantiated())  return false;
1684
  return true;
1685
}
1686

1687
bool Dependencies::has_finalizable_subclass(ciInstanceKlass* k) {
1688
  return k->has_finalizable_subclass();
1689
}
1690

1691
// Any use of the contents (bytecodes) of a method must be
1692
// marked by an "evol_method" dependency, if those contents
1693
// can change.  (Note: A method is always dependent on itself.)
1694
Klass* Dependencies::check_evol_method(Method* m) {
1695
  assert(must_be_in_vm(), "raw oops here");
1696
  // Did somebody do a JVMTI RedefineClasses while our backs were turned?
1697
  // Or is there a now a breakpoint?
1698
  // (Assumes compiled code cannot handle bkpts; change if UseFastBreakpoints.)
1699
  if (m->is_old()
1700
      || m->number_of_breakpoints() > 0) {
1701
    return m->method_holder();
1702
  } else {
1703
    return nullptr;
1704
  }
1705
}
1706

1707
// This is a strong assertion:  It is that the given type
1708
// has no subtypes whatever.  It is most useful for
1709
// optimizing checks on reflected types or on array types.
1710
// (Checks on types which are derived from real instances
1711
// can be optimized more strongly than this, because we
1712
// know that the checked type comes from a concrete type,
1713
// and therefore we can disregard abstract types.)
1714
Klass* Dependencies::check_leaf_type(InstanceKlass* ctxk) {
1715
  assert(must_be_in_vm(), "raw oops here");
1716
  assert_locked_or_safepoint(Compile_lock);
1717
  Klass* sub = ctxk->subklass();
1718
  if (sub != nullptr) {
1719
    return sub;
1720
  } else if (ctxk->nof_implementors() != 0) {
1721
    // if it is an interface, it must be unimplemented
1722
    // (if it is not an interface, nof_implementors is always zero)
1723
    InstanceKlass* impl = ctxk->implementor();
1724
    assert(impl != nullptr, "must be set");
1725
    return impl;
1726
  } else {
1727
    return nullptr;
1728
  }
1729
}
1730

1731
// Test the assertion that conck is the only concrete subtype* of ctxk.
1732
// The type conck itself is allowed to have have further concrete subtypes.
1733
// This allows the compiler to narrow occurrences of ctxk by conck,
1734
// when dealing with the types of actual instances.
1735
Klass* Dependencies::check_abstract_with_unique_concrete_subtype(InstanceKlass* ctxk,
1736
                                                                 Klass* conck,
1737
                                                                 NewKlassDepChange* changes) {
1738
  ConcreteSubtypeFinder wf(conck);
1739
  Klass* k = wf.find_witness(ctxk, changes);
1740
  return k;
1741
}
1742

1743

1744
// Find the unique concrete proper subtype of ctxk, or nullptr if there
1745
// is more than one concrete proper subtype.  If there are no concrete
1746
// proper subtypes, return ctxk itself, whether it is concrete or not.
1747
// The returned subtype is allowed to have have further concrete subtypes.
1748
// That is, return CC1 for CX > CC1 > CC2, but nullptr for CX > { CC1, CC2 }.
1749
Klass* Dependencies::find_unique_concrete_subtype(InstanceKlass* ctxk) {
1750
  ConcreteSubtypeFinder wf(ctxk);  // Ignore ctxk when walking.
1751
  wf.record_witnesses(1);          // Record one other witness when walking.
1752
  Klass* wit = wf.find_witness(ctxk);
1753
  if (wit != nullptr)  return nullptr;   // Too many witnesses.
1754
  Klass* conck = wf.participant(0);
1755
  if (conck == nullptr) {
1756
    return ctxk;                   // Return ctxk as a flag for "no subtypes".
1757
  } else {
1758
#ifndef PRODUCT
1759
    // Make sure the dependency mechanism will pass this discovery:
1760
    if (VerifyDependencies) {
1761
      // Turn off dependency tracing while actually testing deps.
1762
      FlagSetting fs(_verify_in_progress, true);
1763
      if (!Dependencies::is_concrete_klass(ctxk)) {
1764
        guarantee(nullptr == (void *)
1765
                  check_abstract_with_unique_concrete_subtype(ctxk, conck),
1766
                  "verify dep.");
1767
      }
1768
    }
1769
#endif //PRODUCT
1770
    return conck;
1771
  }
1772
}
1773

1774
// Try to determine whether root method in some context is concrete or not based on the information about the unique method
1775
// in that context. It exploits the fact that concrete root method is always inherited into the context when there's a unique method.
1776
// Hence, unique method holder is always a supertype of the context class when root method is concrete.
1777
// Examples for concrete_root_method
1778
//      C (C.m uniqm)
1779
//      |
1780
//      CX (ctxk) uniqm is inherited into context.
1781
//
1782
//      CX (ctxk) (CX.m uniqm) here uniqm is defined in ctxk.
1783
// Examples for !concrete_root_method
1784
//      CX (ctxk)
1785
//      |
1786
//      C (C.m uniqm) uniqm is in subtype of ctxk.
1787
bool Dependencies::is_concrete_root_method(Method* uniqm, InstanceKlass* ctxk) {
1788
  if (uniqm == nullptr) {
1789
    return false; // match Dependencies::is_concrete_method() behavior
1790
  }
1791
  // Theoretically, the "direction" of subtype check matters here.
1792
  // On one hand, in case of interface context with a single implementor, uniqm can be in a superclass of the implementor which
1793
  // is not related to context class.
1794
  // On another hand, uniqm could come from an interface unrelated to the context class, but right now it is not possible:
1795
  // it is required that uniqm->method_holder() is the participant (uniqm->method_holder() <: ctxk), hence a default method
1796
  // can't be used as unique.
1797
  if (ctxk->is_interface()) {
1798
    InstanceKlass* implementor = ctxk->implementor();
1799
    assert(implementor != ctxk, "single implementor only"); // should have been invalidated earlier
1800
    ctxk = implementor;
1801
  }
1802
  InstanceKlass* holder = uniqm->method_holder();
1803
  assert(!holder->is_interface(), "no default methods allowed");
1804
  assert(ctxk->is_subclass_of(holder) || holder->is_subclass_of(ctxk), "not related");
1805
  return ctxk->is_subclass_of(holder);
1806
}
1807

1808
// If a class (or interface) has a unique concrete method uniqm, return nullptr.
1809
// Otherwise, return a class that contains an interfering method.
1810
Klass* Dependencies::check_unique_concrete_method(InstanceKlass* ctxk,
1811
                                                  Method* uniqm,
1812
                                                  NewKlassDepChange* changes) {
1813
  ConcreteMethodFinder wf(uniqm, uniqm->method_holder());
1814
  Klass* k = wf.find_witness(ctxk, changes);
1815
  if (k != nullptr) {
1816
    return k;
1817
  }
1818
  if (!Dependencies::is_concrete_root_method(uniqm, ctxk) || changes != nullptr) {
1819
    Klass* conck = find_witness_AME(ctxk, uniqm, changes);
1820
    if (conck != nullptr) {
1821
      // Found a concrete subtype 'conck' which does not override abstract root method.
1822
      return conck;
1823
    }
1824
  }
1825
  return nullptr;
1826
}
1827

1828
Klass* Dependencies::check_unique_implementor(InstanceKlass* ctxk, Klass* uniqk, NewKlassDepChange* changes) {
1829
  assert(ctxk->is_interface(), "sanity");
1830
  assert(ctxk->nof_implementors() > 0, "no implementors");
1831
  if (ctxk->nof_implementors() == 1) {
1832
    assert(ctxk->implementor() == uniqk, "sanity");
1833
    return nullptr;
1834
  }
1835
  return ctxk; // no unique implementor
1836
}
1837

1838
// Search for AME.
1839
// There are two version of checks.
1840
//   1) Spot checking version(Classload time). Newly added class is checked for AME.
1841
//      Checks whether abstract/overpass method is inherited into/declared in newly added concrete class.
1842
//   2) Compile time analysis for abstract/overpass(abstract klass) root_m. The non uniqm subtrees are checked for concrete classes.
1843
Klass* Dependencies::find_witness_AME(InstanceKlass* ctxk, Method* m, KlassDepChange* changes) {
1844
  if (m != nullptr) {
1845
    if (changes != nullptr) {
1846
      // Spot checking version.
1847
      ConcreteMethodFinder wf(m);
1848
      Klass* new_type = changes->as_new_klass_change()->new_type();
1849
      if (wf.witnessed_reabstraction_in_supers(new_type)) {
1850
        return new_type;
1851
      }
1852
    } else {
1853
      // Note: It is required that uniqm->method_holder() is the participant (see ClassHierarchyWalker::found_method()).
1854
      ConcreteSubtypeFinder wf(m->method_holder());
1855
      Klass* conck = wf.find_witness(ctxk);
1856
      if (conck != nullptr) {
1857
        Method* cm = InstanceKlass::cast(conck)->find_instance_method(m->name(), m->signature(), Klass::PrivateLookupMode::skip);
1858
        if (!Dependencies::is_concrete_method(cm, conck)) {
1859
          return conck;
1860
        }
1861
      }
1862
    }
1863
  }
1864
  return nullptr;
1865
}
1866

1867
// This function is used by find_unique_concrete_method(non vtable based)
1868
// to check whether subtype method overrides the base method.
1869
static bool overrides(Method* sub_m, Method* base_m) {
1870
  assert(base_m != nullptr, "base method should be non null");
1871
  if (sub_m == nullptr) {
1872
    return false;
1873
  }
1874
  /**
1875
   *  If base_m is public or protected then sub_m always overrides.
1876
   *  If base_m is !public, !protected and !private (i.e. base_m is package private)
1877
   *  then sub_m should be in the same package as that of base_m.
1878
   *  For package private base_m this is conservative approach as it allows only subset of all allowed cases in
1879
   *  the jvm specification.
1880
   **/
1881
  if (base_m->is_public() || base_m->is_protected() ||
1882
      base_m->method_holder()->is_same_class_package(sub_m->method_holder())) {
1883
    return true;
1884
  }
1885
  return false;
1886
}
1887

1888
// Find the set of all non-abstract methods under ctxk that match m.
1889
// (The method m must be defined or inherited in ctxk.)
1890
// Include m itself in the set, unless it is abstract.
1891
// If this set has exactly one element, return that element.
1892
Method* Dependencies::find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass** participant) {
1893
  // Return nullptr if m is marked old; must have been a redefined method.
1894
  if (m->is_old()) {
1895
    return nullptr;
1896
  }
1897
  if (m->is_default_method()) {
1898
    return nullptr; // not supported
1899
  }
1900
  assert(verify_method_context(ctxk, m), "proper context");
1901
  ConcreteMethodFinder wf(m);
1902
  wf.record_witnesses(1);
1903
  Klass* wit = wf.find_witness(ctxk);
1904
  if (wit != nullptr)  return nullptr;  // Too many witnesses.
1905
  Method* fm = wf.found_method(0);  // Will be nullptr if num_parts == 0.
1906
  if (participant != nullptr) {
1907
    (*participant) = wf.participant(0);
1908
  }
1909
  if (!Dependencies::is_concrete_method(fm, nullptr)) {
1910
    fm = nullptr; // ignore abstract methods
1911
  }
1912
  if (Dependencies::is_concrete_method(m, ctxk)) {
1913
    if (fm == nullptr) {
1914
      // It turns out that m was always the only implementation.
1915
      fm = m;
1916
    } else if (fm != m) {
1917
      // Two conflicting implementations after all.
1918
      // (This can happen if m is inherited into ctxk and fm overrides it.)
1919
      return nullptr;
1920
    }
1921
  } else if (Dependencies::find_witness_AME(ctxk, fm) != nullptr) {
1922
    // Found a concrete subtype which does not override abstract root method.
1923
    return nullptr;
1924
  } else if (!overrides(fm, m)) {
1925
    // Found method doesn't override abstract root method.
1926
    return nullptr;
1927
  }
1928
  assert(Dependencies::is_concrete_root_method(fm, ctxk) == Dependencies::is_concrete_method(m, ctxk), "mismatch");
1929
#ifndef PRODUCT
1930
  // Make sure the dependency mechanism will pass this discovery:
1931
  if (VerifyDependencies && fm != nullptr) {
1932
    guarantee(nullptr == (void *)check_unique_concrete_method(ctxk, fm),
1933
              "verify dep.");
1934
  }
1935
#endif //PRODUCT
1936
  return fm;
1937
}
1938

1939
// If a class (or interface) has a unique concrete method uniqm, return nullptr.
1940
// Otherwise, return a class that contains an interfering method.
1941
Klass* Dependencies::check_unique_concrete_method(InstanceKlass* ctxk,
1942
                                                  Method* uniqm,
1943
                                                  Klass* resolved_klass,
1944
                                                  Method* resolved_method,
1945
                                                  KlassDepChange* changes) {
1946
  assert(!ctxk->is_interface() || ctxk == resolved_klass, "sanity");
1947
  assert(!resolved_method->can_be_statically_bound() || resolved_method == uniqm, "sanity");
1948
  assert(resolved_klass->is_subtype_of(resolved_method->method_holder()), "sanity");
1949

1950
  if (!InstanceKlass::cast(resolved_klass)->is_linked() ||
1951
      !resolved_method->method_holder()->is_linked() ||
1952
      resolved_method->can_be_statically_bound()) {
1953
    // Dependency is redundant, but benign. Just keep it to avoid unnecessary recompilation.
1954
    return nullptr; // no vtable index available
1955
  }
1956

1957
  LinkedConcreteMethodFinder mf(InstanceKlass::cast(resolved_klass), resolved_method, uniqm);
1958
  return mf.find_witness(ctxk, changes);
1959
}
1960

1961
// Find the set of all non-abstract methods under ctxk that match m.
1962
// (The method m must be defined or inherited in ctxk.)
1963
// Include m itself in the set, unless it is abstract.
1964
// If this set has exactly one element, return that element.
1965
// Not yet linked subclasses of ctxk are ignored since they don't have any instances yet.
1966
// Additionally, resolved_klass and resolved_method complete the description of the call site being analyzed.
1967
Method* Dependencies::find_unique_concrete_method(InstanceKlass* ctxk, Method* m, Klass* resolved_klass, Method* resolved_method) {
1968
  // Return nullptr if m is marked old; must have been a redefined method.
1969
  if (m->is_old()) {
1970
    return nullptr;
1971
  }
1972
  if (!InstanceKlass::cast(resolved_klass)->is_linked() ||
1973
      !resolved_method->method_holder()->is_linked() ||
1974
      resolved_method->can_be_statically_bound()) {
1975
    return m; // nothing to do: no witness under ctxk
1976
  }
1977
  LinkedConcreteMethodFinder wf(InstanceKlass::cast(resolved_klass), resolved_method);
1978
  assert(Dependencies::verify_method_context(ctxk, m), "proper context");
1979
  wf.record_witnesses(1);
1980
  Klass* wit = wf.find_witness(ctxk);
1981
  if (wit != nullptr) {
1982
    return nullptr;  // Too many witnesses.
1983
  }
1984
  // p == nullptr when no participants are found (wf.num_participants() == 0).
1985
  // fm == nullptr case has 2 meanings:
1986
  //  * when p == nullptr: no method found;
1987
  //  * when p != nullptr: AbstractMethodError-throwing method found.
1988
  // Also, found method should always be accompanied by a participant class.
1989
  Klass*   p = wf.participant(0);
1990
  Method* fm = wf.found_method(0);
1991
  assert(fm == nullptr || p != nullptr, "no participant");
1992
  // Normalize all error-throwing cases to nullptr.
1993
  if (fm == Universe::throw_illegal_access_error() ||
1994
      fm == Universe::throw_no_such_method_error() ||
1995
      !Dependencies::is_concrete_method(fm, p)) {
1996
    fm = nullptr; // error-throwing method
1997
  }
1998
  if (Dependencies::is_concrete_method(m, ctxk)) {
1999
    if (p == nullptr) {
2000
      // It turns out that m was always the only implementation.
2001
      assert(fm == nullptr, "sanity");
2002
      fm = m;
2003
    }
2004
  }
2005
#ifndef PRODUCT
2006
  // Make sure the dependency mechanism will pass this discovery:
2007
  if (VerifyDependencies && fm != nullptr) {
2008
    guarantee(nullptr == check_unique_concrete_method(ctxk, fm, resolved_klass, resolved_method),
2009
              "verify dep.");
2010
  }
2011
#endif // PRODUCT
2012
  assert(fm == nullptr || !fm->is_abstract(), "sanity");
2013
  // Old CHA conservatively reports concrete methods in abstract classes
2014
  // irrespective of whether they have concrete subclasses or not.
2015
  // Also, abstract root method case is not fully supported.
2016
#ifdef ASSERT
2017
  Klass*  uniqp = nullptr;
2018
  Method* uniqm = Dependencies::find_unique_concrete_method(ctxk, m, &uniqp);
2019
  assert(uniqm == nullptr || uniqm == fm ||
2020
         m->is_abstract() ||
2021
         uniqm->method_holder()->is_abstract() ||
2022
         (fm == nullptr && uniqm != nullptr && uniqp != nullptr && !InstanceKlass::cast(uniqp)->is_linked()),
2023
         "sanity");
2024
#endif // ASSERT
2025
  return fm;
2026
}
2027

2028
Klass* Dependencies::check_has_no_finalizable_subclasses(InstanceKlass* ctxk, NewKlassDepChange* changes) {
2029
  InstanceKlass* search_at = ctxk;
2030
  if (changes != nullptr) {
2031
    search_at = changes->new_type(); // just look at the new bit
2032
  }
2033
  return find_finalizable_subclass(search_at);
2034
}
2035

2036
Klass* Dependencies::check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes) {
2037
  assert(call_site != nullptr, "sanity");
2038
  assert(method_handle != nullptr, "sanity");
2039
  assert(call_site->is_a(vmClasses::CallSite_klass()),     "sanity");
2040

2041
  if (changes == nullptr) {
2042
    // Validate all CallSites
2043
    if (java_lang_invoke_CallSite::target(call_site) != method_handle)
2044
      return call_site->klass();  // assertion failed
2045
  } else {
2046
    // Validate the given CallSite
2047
    if (call_site == changes->call_site() && java_lang_invoke_CallSite::target(call_site) != changes->method_handle()) {
2048
      assert(method_handle != changes->method_handle(), "must be");
2049
      return call_site->klass();  // assertion failed
2050
    }
2051
  }
2052
  return nullptr;  // assertion still valid
2053
}
2054

2055
void Dependencies::DepStream::trace_and_log_witness(Klass* witness) {
2056
  if (_verify_in_progress) return;  // don't log
2057
  if (witness != nullptr) {
2058
    LogTarget(Debug, dependencies) lt;
2059
    if (lt.is_enabled()) {
2060
      LogStream ls(&lt);
2061
      print_dependency(&ls, witness, /*verbose=*/ true);
2062
    }
2063
    // The following is a no-op unless logging is enabled:
2064
    log_dependency(witness);
2065
  }
2066
}
2067

2068
Klass* Dependencies::DepStream::check_new_klass_dependency(NewKlassDepChange* changes) {
2069
  assert_locked_or_safepoint(Compile_lock);
2070
  Dependencies::check_valid_dependency_type(type());
2071

2072
  Klass* witness = nullptr;
2073
  switch (type()) {
2074
  case evol_method:
2075
    witness = check_evol_method(method_argument(0));
2076
    break;
2077
  case leaf_type:
2078
    witness = check_leaf_type(context_type());
2079
    break;
2080
  case abstract_with_unique_concrete_subtype:
2081
    witness = check_abstract_with_unique_concrete_subtype(context_type(), type_argument(1), changes);
2082
    break;
2083
  case unique_concrete_method_2:
2084
    witness = check_unique_concrete_method(context_type(), method_argument(1), changes);
2085
    break;
2086
  case unique_concrete_method_4:
2087
    witness = check_unique_concrete_method(context_type(), method_argument(1), type_argument(2), method_argument(3), changes);
2088
    break;
2089
  case unique_implementor:
2090
    witness = check_unique_implementor(context_type(), type_argument(1), changes);
2091
    break;
2092
  case no_finalizable_subclasses:
2093
    witness = check_has_no_finalizable_subclasses(context_type(), changes);
2094
    break;
2095
  default:
2096
    witness = nullptr;
2097
    break;
2098
  }
2099
  trace_and_log_witness(witness);
2100
  return witness;
2101
}
2102

2103
Klass* Dependencies::DepStream::check_klass_init_dependency(KlassInitDepChange* changes) {
2104
  assert_locked_or_safepoint(Compile_lock);
2105
  Dependencies::check_valid_dependency_type(type());
2106

2107
  // No new types added. Only unique_concrete_method_4 is sensitive to class initialization changes.
2108
  Klass* witness = nullptr;
2109
  switch (type()) {
2110
  case unique_concrete_method_4:
2111
    witness = check_unique_concrete_method(context_type(), method_argument(1), type_argument(2), method_argument(3), changes);
2112
    break;
2113
  default:
2114
    witness = nullptr;
2115
    break;
2116
  }
2117
  trace_and_log_witness(witness);
2118
  return witness;
2119
}
2120

2121
Klass* Dependencies::DepStream::check_klass_dependency(KlassDepChange* changes) {
2122
  assert_locked_or_safepoint(Compile_lock);
2123
  Dependencies::check_valid_dependency_type(type());
2124

2125
  if (changes != nullptr) {
2126
    if (changes->is_klass_init_change()) {
2127
      return check_klass_init_dependency(changes->as_klass_init_change());
2128
    } else {
2129
      return check_new_klass_dependency(changes->as_new_klass_change());
2130
    }
2131
  } else {
2132
    Klass* witness = check_new_klass_dependency(nullptr);
2133
    // check_klass_init_dependency duplicates check_new_klass_dependency checks when class hierarchy change info is absent.
2134
    assert(witness != nullptr || check_klass_init_dependency(nullptr) == nullptr, "missed dependency");
2135
    return witness;
2136
  }
2137
}
2138

2139
Klass* Dependencies::DepStream::check_call_site_dependency(CallSiteDepChange* changes) {
2140
  assert_locked_or_safepoint(Compile_lock);
2141
  Dependencies::check_valid_dependency_type(type());
2142

2143
  Klass* witness = nullptr;
2144
  switch (type()) {
2145
  case call_site_target_value:
2146
    witness = check_call_site_target_value(argument_oop(0), argument_oop(1), changes);
2147
    break;
2148
  default:
2149
    witness = nullptr;
2150
    break;
2151
  }
2152
  trace_and_log_witness(witness);
2153
  return witness;
2154
}
2155

2156

2157
Klass* Dependencies::DepStream::spot_check_dependency_at(DepChange& changes) {
2158
  // Handle klass dependency
2159
  if (changes.is_klass_change() && changes.as_klass_change()->involves_context(context_type()))
2160
    return check_klass_dependency(changes.as_klass_change());
2161

2162
  // Handle CallSite dependency
2163
  if (changes.is_call_site_change())
2164
    return check_call_site_dependency(changes.as_call_site_change());
2165

2166
  // irrelevant dependency; skip it
2167
  return nullptr;
2168
}
2169

2170

2171
void DepChange::print() { print_on(tty); }
2172

2173
void DepChange::print_on(outputStream* st) {
2174
  int nsup = 0, nint = 0;
2175
  for (ContextStream str(*this); str.next(); ) {
2176
    InstanceKlass* k = str.klass();
2177
    switch (str.change_type()) {
2178
    case Change_new_type:
2179
      st->print_cr("  dependee = %s", k->external_name());
2180
      break;
2181
    case Change_new_sub:
2182
      if (!WizardMode) {
2183
        ++nsup;
2184
      } else {
2185
        st->print_cr("  context super = %s", k->external_name());
2186
      }
2187
      break;
2188
    case Change_new_impl:
2189
      if (!WizardMode) {
2190
        ++nint;
2191
      } else {
2192
        st->print_cr("  context interface = %s", k->external_name());
2193
      }
2194
      break;
2195
    default:
2196
      break;
2197
    }
2198
  }
2199
  if (nsup + nint != 0) {
2200
    st->print_cr("  context supers = %d, interfaces = %d", nsup, nint);
2201
  }
2202
}
2203

2204
void DepChange::ContextStream::start() {
2205
  InstanceKlass* type = (_changes.is_klass_change() ? _changes.as_klass_change()->type() : (InstanceKlass*) nullptr);
2206
  _change_type = (type == nullptr ? NO_CHANGE : Start_Klass);
2207
  _klass = type;
2208
  _ti_base = nullptr;
2209
  _ti_index = 0;
2210
  _ti_limit = 0;
2211
}
2212

2213
bool DepChange::ContextStream::next() {
2214
  switch (_change_type) {
2215
  case Start_Klass:             // initial state; _klass is the new type
2216
    _ti_base = _klass->transitive_interfaces();
2217
    _ti_index = 0;
2218
    _change_type = Change_new_type;
2219
    return true;
2220
  case Change_new_type:
2221
    // fall through:
2222
    _change_type = Change_new_sub;
2223
  case Change_new_sub:
2224
    // 6598190: brackets workaround Sun Studio C++ compiler bug 6629277
2225
    {
2226
      _klass = _klass->java_super();
2227
      if (_klass != nullptr) {
2228
        return true;
2229
      }
2230
    }
2231
    // else set up _ti_limit and fall through:
2232
    _ti_limit = (_ti_base == nullptr) ? 0 : _ti_base->length();
2233
    _change_type = Change_new_impl;
2234
  case Change_new_impl:
2235
    if (_ti_index < _ti_limit) {
2236
      _klass = _ti_base->at(_ti_index++);
2237
      return true;
2238
    }
2239
    // fall through:
2240
    _change_type = NO_CHANGE;  // iterator is exhausted
2241
  case NO_CHANGE:
2242
    break;
2243
  default:
2244
    ShouldNotReachHere();
2245
  }
2246
  return false;
2247
}
2248

2249
void KlassDepChange::initialize() {
2250
  // entire transaction must be under this lock:
2251
  assert_lock_strong(Compile_lock);
2252

2253
  // Mark all dependee and all its superclasses
2254
  // Mark transitive interfaces
2255
  for (ContextStream str(*this); str.next(); ) {
2256
    InstanceKlass* d = str.klass();
2257
    assert(!d->is_marked_dependent(), "checking");
2258
    d->set_is_marked_dependent(true);
2259
  }
2260
}
2261

2262
KlassDepChange::~KlassDepChange() {
2263
  // Unmark all dependee and all its superclasses
2264
  // Unmark transitive interfaces
2265
  for (ContextStream str(*this); str.next(); ) {
2266
    InstanceKlass* d = str.klass();
2267
    d->set_is_marked_dependent(false);
2268
  }
2269
}
2270

2271
bool KlassDepChange::involves_context(Klass* k) {
2272
  if (k == nullptr || !k->is_instance_klass()) {
2273
    return false;
2274
  }
2275
  InstanceKlass* ik = InstanceKlass::cast(k);
2276
  bool is_contained = ik->is_marked_dependent();
2277
  assert(is_contained == type()->is_subtype_of(k),
2278
         "correct marking of potential context types");
2279
  return is_contained;
2280
}
2281

2282
void Dependencies::print_statistics() {
2283
  AbstractClassHierarchyWalker::print_statistics();
2284
}
2285

2286
void AbstractClassHierarchyWalker::print_statistics() {
2287
  if (UsePerfData) {
2288
    jlong deps_find_witness_calls   = _perf_find_witness_anywhere_calls_count->get_value();
2289
    jlong deps_find_witness_steps   = _perf_find_witness_anywhere_steps_count->get_value();
2290
    jlong deps_find_witness_singles = _perf_find_witness_in_calls_count->get_value();
2291

2292
    ttyLocker ttyl;
2293
    tty->print_cr("Dependency check (find_witness) "
2294
                  "calls=" JLONG_FORMAT ", steps=" JLONG_FORMAT " (avg=%.1f), singles=" JLONG_FORMAT,
2295
                  deps_find_witness_calls,
2296
                  deps_find_witness_steps,
2297
                  (double)deps_find_witness_steps / deps_find_witness_calls,
2298
                  deps_find_witness_singles);
2299
    if (xtty != nullptr) {
2300
      xtty->elem("deps_find_witness calls='" JLONG_FORMAT "' steps='" JLONG_FORMAT "' singles='" JLONG_FORMAT "'",
2301
                 deps_find_witness_calls,
2302
                 deps_find_witness_steps,
2303
                 deps_find_witness_singles);
2304
    }
2305
  }
2306
}
2307

2308
CallSiteDepChange::CallSiteDepChange(Handle call_site, Handle method_handle) :
2309
  _call_site(call_site),
2310
  _method_handle(method_handle) {
2311
  assert(_call_site()->is_a(vmClasses::CallSite_klass()), "must be");
2312
  assert(_method_handle.is_null() || _method_handle()->is_a(vmClasses::MethodHandle_klass()), "must be");
2313
}
2314

2315
void dependencies_init() {
2316
  AbstractClassHierarchyWalker::init();
2317
}
2318