view src/share/vm/oops/oop.pcgc.inline.hpp @ 1992:3cd116fd11be

6994628: G1: Test gc/gctests/FinalizeTest05 fails (one live object is finalized) Summary: The Solaris Studio 12 update 1 C++ compiler was incorrectly re-ordering the reads of an object's mark word in oopDesc::forward_to_atomic(). This opened a small window where one thread could execute the successful CAS path even though another thread had already successfully forwarded the object. This could result in an object being copied twice. The code in oopDesc::forward_to_atomic() was changed to read the mark word once. Reviewed-by: ysr, tonyp
author johnc
date Tue, 07 Dec 2010 16:18:45 -0800
parents f95d63e2154a
children e5383553fd4e
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/*
 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
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 */

#ifndef SHARE_VM_OOPS_OOP_PCGC_INLINE_HPP
#define SHARE_VM_OOPS_OOP_PCGC_INLINE_HPP

#ifndef SERIALGC
#include "gc_implementation/parNew/parNewGeneration.hpp"
#include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
#include "gc_implementation/parallelScavenge/psCompactionManager.hpp"
#include "gc_implementation/parallelScavenge/psParallelCompact.hpp"
#include "gc_implementation/parallelScavenge/psScavenge.hpp"
#include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
#endif

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 (!oldMark->is_marked()) {
    curMark = (markOop)Atomic::cmpxchg_ptr(forwardPtrMark, &_mark, oldMark);
    assert(is_forwarded(), "object should have been forwarded");
    if (curMark == oldMark) {
      return NULL;
    }
    // If the CAS was unsuccessful then curMark->is_marked()
    // should return true as another thread has CAS'd in another
    // forwarding pointer.
    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);
  }
}

#endif // SHARE_VM_OOPS_OOP_PCGC_INLINE_HPP