src/hotspot/share/gc/shenandoah/shenandoahRootVerifier.cpp

/*
 * Copyright (c) 2019, 2021, Red Hat, Inc. All rights reserved.
 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
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#include "classfile/classLoaderDataGraph.hpp"
#include "code/codeCache.hpp"
#include "gc/shared/oopStorage.inline.hpp"
#include "gc/shared/oopStorageSet.hpp"
#include "gc/shenandoah/shenandoahAsserts.hpp"
#include "gc/shenandoah/shenandoahGeneration.hpp"
#include "gc/shenandoah/shenandoahHeap.inline.hpp"
#include "gc/shenandoah/shenandoahPhaseTimings.hpp"
#include "gc/shenandoah/shenandoahRootVerifier.hpp"
#include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
#include "gc/shenandoah/shenandoahStringDedup.hpp"
#include "gc/shenandoah/shenandoahUtils.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/jniHandles.hpp"
#include "runtime/threads.hpp"
#include "utilities/debug.hpp"
#include "utilities/enumIterator.hpp"

ShenandoahGCStateResetter::ShenandoahGCStateResetter() :
  _heap(ShenandoahHeap::heap()),
  _saved_gc_state(_heap->gc_state()),
  _saved_gc_state_changed(_heap->_gc_state_changed) {
  // Clear state to deactivate barriers. Indicate that state has changed
  // so that verifier threads will use this value, rather than thread local
  // values (which we are _not_ changing here).
  _heap->_gc_state.clear();
  _heap->_gc_state_changed = true;
}

ShenandoahGCStateResetter::~ShenandoahGCStateResetter() {
  _heap->_gc_state.set(_saved_gc_state);
  _heap->_gc_state_changed = _saved_gc_state_changed;
  assert(_heap->gc_state() == _saved_gc_state, "Should be restored");
}

void ShenandoahRootVerifier::roots_do(OopIterateClosure* oops) {
  ShenandoahGCStateResetter resetter;
  shenandoah_assert_safepoint();

  NMethodToOopClosure blobs(oops, !NMethodToOopClosure::FixRelocations);
  CodeCache::nmethods_do(&blobs);

  CLDToOopClosure clds(oops, ClassLoaderData::_claim_none);
  ClassLoaderDataGraph::cld_do(&clds);

  for (auto id : EnumRange<OopStorageSet::StrongId>()) {
    OopStorageSet::storage(id)->oops_do(oops);
  }

  ShenandoahHeap* heap = ShenandoahHeap::heap();
  if (heap->mode()->is_generational() && heap->active_generation()->is_young()) {
    shenandoah_assert_safepoint();
    ShenandoahGenerationalHeap::heap()->old_generation()->card_scan()->roots_do(oops);
  }

  // Do thread roots the last. This allows verification code to find
  // any broken objects from those special roots first, not the accidental
  // dangling reference from the thread root.
  Threads::possibly_parallel_oops_do(true, oops, nullptr);
}

void ShenandoahRootVerifier::strong_roots_do(OopIterateClosure* oops) {
  ShenandoahGCStateResetter resetter;
  shenandoah_assert_safepoint();

  CLDToOopClosure clds(oops, ClassLoaderData::_claim_none);
  ClassLoaderDataGraph::always_strong_cld_do(&clds);

  for (auto id : EnumRange<OopStorageSet::StrongId>()) {
    OopStorageSet::storage(id)->oops_do(oops);
  }

  ShenandoahHeap* heap = ShenandoahHeap::heap();
  if (heap->mode()->is_generational() && heap->active_generation()->is_young()) {
    ShenandoahGenerationalHeap::heap()->old_generation()->card_scan()->roots_do(oops);
  }

  // Do thread roots the last. This allows verification code to find
  // any broken objects from those special roots first, not the accidental
  // dangling reference from the thread root.
  NMethodToOopClosure nmethods(oops, !NMethodToOopClosure::FixRelocations);
  Threads::possibly_parallel_oops_do(true, oops, &nmethods);
}