view src/share/vm/oops/oop.pcgc.inline.hpp @ 452:00b023ae2d78

6722113: CMS: Incorrect overflow handling during precleaning of Reference lists Summary: When we encounter marking stack overflow during precleaning of Reference lists, we were using the overflow list mechanism, which can cause problems on account of mutating the mark word of the header because of conflicts with mutator accesses and updates of that field. Instead we should use the usual mechanism for overflow handling in concurrent phases, namely dirtying of the card on which the overflowed object lies. Since precleaning effectively does a form of discovered list processing, albeit with discovery enabled, we needed to adjust some code to be correct in the face of interleaved processing and discovery. Reviewed-by: apetrusenko, jcoomes
author ysr
date Thu, 20 Nov 2008 12:27:41 -0800
parents d1605aabd0a1
children c18cbe5936b8
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/*
 * Copyright 2005-2008 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 */

inline void oopDesc::update_contents(ParCompactionManager* cm) {
  // The klass field must be updated before anything else
  // can be done.
  DEBUG_ONLY(klassOopDesc* original_klass = klass());

  // Can the option to update and/or copy be moved up in the
  // call chain to avoid calling into here?

  if (PSParallelCompact::should_update_klass(klass())) {
    update_header();
    assert(klass()->is_klass(), "Not updated correctly");
  } else {
    assert(klass()->is_klass(), "Not updated");
  }

  Klass* new_klass = blueprint();
  if (!new_klass->oop_is_typeArray()) {
    // It might contain oops beyond the header, so take the virtual call.
    new_klass->oop_update_pointers(cm, this);
  }
  // Else skip it.  The typeArrayKlass in the header never needs scavenging.
}

inline void oopDesc::update_contents(ParCompactionManager* cm,
                                     HeapWord* begin_limit,
                                     HeapWord* end_limit) {
  // The klass field must be updated before anything else
  // can be done.
  debug_only(klassOopDesc* original_klass = klass());

  update_contents(cm, klass(), begin_limit, end_limit);
}

inline void oopDesc::update_contents(ParCompactionManager* cm,
                                     klassOop old_klass,
                                     HeapWord* begin_limit,
                                     HeapWord* end_limit) {

  klassOop updated_klass =
    PSParallelCompact::summary_data().calc_new_klass(old_klass);

  // Needs to be boundary aware for the 64 bit case
  // update_header();
  // The klass has moved.  Is the location of the klass
  // within the limits?
  if ((((HeapWord*)&_metadata._klass) >= begin_limit) &&
      (((HeapWord*)&_metadata._klass) < end_limit)) {
    set_klass(updated_klass);
  }

  Klass* klass = updated_klass->klass_part();
  if (!klass->oop_is_typeArray()) {
    // It might contain oops beyond the header, so take the virtual call.
    klass->oop_update_pointers(cm, this, begin_limit, end_limit);
  }
  // Else skip it.  The typeArrayKlass in the header never needs scavenging.
}

inline void oopDesc::follow_contents(ParCompactionManager* cm) {
  assert (PSParallelCompact::mark_bitmap()->is_marked(this),
    "should be marked");
  blueprint()->oop_follow_contents(cm, this);
}

// Used by parallel old GC.

inline void oopDesc::follow_header(ParCompactionManager* cm) {
  if (UseCompressedOops) {
    PSParallelCompact::mark_and_push(cm, compressed_klass_addr());
  } else {
    PSParallelCompact::mark_and_push(cm, klass_addr());
  }
}

inline oop oopDesc::forward_to_atomic(oop p) {
  assert(ParNewGeneration::is_legal_forward_ptr(p),
         "illegal forwarding pointer value.");
  markOop oldMark = mark();
  markOop forwardPtrMark = markOopDesc::encode_pointer_as_mark(p);
  markOop curMark;

  assert(forwardPtrMark->decode_pointer() == p, "encoding must be reversable");
  assert(sizeof(markOop) == sizeof(intptr_t), "CAS below requires this.");

  while (!is_forwarded()) {
    curMark = (markOop)Atomic::cmpxchg_ptr(forwardPtrMark, &_mark, oldMark);
    if (curMark == oldMark) {
      assert(is_forwarded(), "the CAS should have succeeded.");
      return NULL;
    }
    oldMark = curMark;
  }
  return forwardee();
}

inline void oopDesc::update_header() {
  if (UseCompressedOops) {
    PSParallelCompact::adjust_pointer(compressed_klass_addr());
  } else {
    PSParallelCompact::adjust_pointer(klass_addr());
  }
}

inline void oopDesc::update_header(HeapWord* beg_addr, HeapWord* end_addr) {
  if (UseCompressedOops) {
    PSParallelCompact::adjust_pointer(compressed_klass_addr(),
                                      beg_addr, end_addr);
  } else {
    PSParallelCompact::adjust_pointer(klass_addr(), beg_addr, end_addr);
  }
}