JDK14/Java14源码在线阅读

/*
 * Copyright (c) 2017, 2019, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

#include "precompiled.hpp"
#include "gc/z/zGlobals.hpp"
#include "runtime/globals.hpp"
#include "utilities/globalDefinitions.hpp"
#include "utilities/powerOfTwo.hpp"

//
// The heap can have three different layouts, depending on the max heap size.
//
// Address Space & Pointer Layout 1
// --------------------------------
//
//  +--------------------------------+ 0x00007FFFFFFFFFFF (127TB)
//  .                                .
//  .                                .
//  .                                .
//  +--------------------------------+ 0x0000014000000000 (20TB)
//  |         Remapped View          |
//  +--------------------------------+ 0x0000010000000000 (16TB)
//  .                                .
//  +--------------------------------+ 0x00000c0000000000 (12TB)
//  |         Marked1 View           |
//  +--------------------------------+ 0x0000080000000000 (8TB)
//  |         Marked0 View           |
//  +--------------------------------+ 0x0000040000000000 (4TB)
//  .                                .
//  +--------------------------------+ 0x0000000000000000
//
//   6                  4 4  4 4
//   3                  6 5  2 1                                             0
//  +--------------------+----+-----------------------------------------------+
//  |00000000 00000000 00|1111|11 11111111 11111111 11111111 11111111 11111111|
//  +--------------------+----+-----------------------------------------------+
//  |                    |    |
//  |                    |    * 41-0 Object Offset (42-bits, 4TB address space)
//  |                    |
//  |                    * 45-42 Metadata Bits (4-bits)  0001 = Marked0      (Address view 4-8TB)
//  |                                                    0010 = Marked1      (Address view 8-12TB)
//  |                                                    0100 = Remapped     (Address view 16-20TB)
//  |                                                    1000 = Finalizable  (Address view N/A)
//  |
//  * 63-46 Fixed (18-bits, always zero)
//
//
// Address Space & Pointer Layout 2
// --------------------------------
//
//  +--------------------------------+ 0x00007FFFFFFFFFFF (127TB)
//  .                                .
//  .                                .
//  .                                .
//  +--------------------------------+ 0x0000280000000000 (40TB)
//  |         Remapped View          |
//  +--------------------------------+ 0x0000200000000000 (32TB)
//  .                                .
//  +--------------------------------+ 0x0000180000000000 (24TB)
//  |         Marked1 View           |
//  +--------------------------------+ 0x0000100000000000 (16TB)
//  |         Marked0 View           |
//  +--------------------------------+ 0x0000080000000000 (8TB)
//  .                                .
//  +--------------------------------+ 0x0000000000000000
//
//   6                 4 4  4 4
//   3                 7 6  3 2                                              0
//  +------------------+-----+------------------------------------------------+
//  |00000000 00000000 0|1111|111 11111111 11111111 11111111 11111111 11111111|
//  +-------------------+----+------------------------------------------------+
//  |                   |    |
//  |                   |    * 42-0 Object Offset (43-bits, 8TB address space)
//  |                   |
//  |                   * 46-43 Metadata Bits (4-bits)  0001 = Marked0      (Address view 8-16TB)
//  |                                                   0010 = Marked1      (Address view 16-24TB)
//  |                                                   0100 = Remapped     (Address view 32-40TB)
//  |                                                   1000 = Finalizable  (Address view N/A)
//  |
//  * 63-47 Fixed (17-bits, always zero)
//
//
// Address Space & Pointer Layout 3
// --------------------------------
//
//  +--------------------------------+ 0x00007FFFFFFFFFFF (127TB)
//  .                                .
//  .                                .
//  .                                .
//  +--------------------------------+ 0x0000500000000000 (80TB)
//  |         Remapped View          |
//  +--------------------------------+ 0x0000400000000000 (64TB)
//  .                                .
//  +--------------------------------+ 0x0000300000000000 (48TB)
//  |         Marked1 View           |
//  +--------------------------------+ 0x0000200000000000 (32TB)
//  |         Marked0 View           |
//  +--------------------------------+ 0x0000100000000000 (16TB)
//  .                                .
//  +--------------------------------+ 0x0000000000000000
//
//   6               4  4  4 4
//   3               8  7  4 3                                               0
//  +------------------+----+-------------------------------------------------+
//  |00000000 00000000 |1111|1111 11111111 11111111 11111111 11111111 11111111|
//  +------------------+----+-------------------------------------------------+
//  |                  |    |
//  |                  |    * 43-0 Object Offset (44-bits, 16TB address space)
//  |                  |
//  |                  * 47-44 Metadata Bits (4-bits)  0001 = Marked0      (Address view 16-32TB)
//  |                                                  0010 = Marked1      (Address view 32-48TB)

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