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1 /* |
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2 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. |
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8 * |
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9 * This code is distributed in the hope that it will be useful, but WITHOUT |
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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12 * version 2 for more details (a copy is included in the LICENSE file that |
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13 * accompanied this code). |
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14 * |
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15 * You should have received a copy of the GNU General Public License version |
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16 * 2 along with this work; if not, write to the Free Software Foundation, |
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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18 * |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
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22 */ |
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23 |
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24 #ifndef SHARE_GC_Z_ZMARKSTACKENTRY_HPP |
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25 #define SHARE_GC_Z_ZMARKSTACKENTRY_HPP |
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26 |
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27 #include "gc/z/zBitField.hpp" |
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28 #include "memory/allocation.hpp" |
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29 |
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30 // |
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31 // Mark stack entry layout |
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32 // ----------------------- |
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33 // |
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34 // Object entry |
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35 // ------------ |
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36 // |
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37 // 6 |
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38 // 3 2 1 0 |
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39 // +---------------------------------------------------------------------+-+-+ |
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40 // |11111111 11111111 11111111 11111111 11111111 11111111 11111111 111111|1|1| |
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41 // +---------------------------------------------------------------------+-+-+ |
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42 // | | | |
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43 // | 1-1 Partial Array Flag (1-bit) * | |
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44 // | | |
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45 // | 0-0 Final Flag (1-bit) * |
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46 // | |
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47 // * 63-2 Object Address (62-bits) |
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48 // |
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49 // |
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50 // Partial array entry |
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51 // ------------------- |
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52 // |
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53 // 6 3 3 |
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54 // 3 2 1 2 1 0 |
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55 // +------------------------------------+---------------------------------+-+-+ |
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56 // |11111111 11111111 11111111 11111111 |11111111 11111111 11111111 111111|1|1| |
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57 // +------------------------------------+---------------------------------+-+-+ |
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58 // | | | | |
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59 // | | 1-1 Partial Array Flag (1-bit) * | |
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60 // | | | |
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61 // | | 0-0 Final Flag (1-bit) * |
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62 // | | |
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63 // | * 31-2 Partial Array Length (30-bits) |
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64 // | |
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65 // * 63-32 Partial Array Address Offset (32-bits) |
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66 // |
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67 |
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68 class ZMarkStackEntry { |
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69 private: |
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70 typedef ZBitField<uint64_t, bool, 0, 1> field_finalizable; |
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71 typedef ZBitField<uint64_t, bool, 1, 1> field_partial_array; |
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72 typedef ZBitField<uint64_t, uintptr_t, 2, 62> field_object_address; |
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73 typedef ZBitField<uint64_t, size_t, 2, 30> field_partial_array_length; |
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74 typedef ZBitField<uint64_t, size_t, 32, 32> field_partial_array_offset; |
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75 |
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76 uint64_t _entry; |
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77 |
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78 public: |
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79 ZMarkStackEntry() { |
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80 // This constructor is intentionally left emtpy and does not initialize |
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81 // _entry to allow it to be optimized out when instantiating ZMarkStack, |
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82 // which has a long array of ZMarkStackEntry elements, but doesn't care |
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83 // what _entry is initialized to. |
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84 } |
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85 |
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86 ZMarkStackEntry(uintptr_t object_address, bool finalizable) : |
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87 _entry(field_object_address::encode(object_address) | |
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88 field_partial_array::encode(false) | |
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89 field_finalizable::encode(finalizable)) {} |
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90 |
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91 ZMarkStackEntry(size_t partial_array_offset, size_t partial_array_length, bool finalizable) : |
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92 _entry(field_partial_array_offset::encode(partial_array_offset) | |
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93 field_partial_array_length::encode(partial_array_length) | |
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94 field_partial_array::encode(true) | |
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95 field_finalizable::encode(finalizable)) {} |
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96 |
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97 bool finalizable() const { |
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98 return field_finalizable::decode(_entry); |
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99 } |
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100 |
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101 bool partial_array() const { |
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102 return field_partial_array::decode(_entry); |
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103 } |
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104 |
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105 size_t partial_array_offset() const { |
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106 return field_partial_array_offset::decode(_entry); |
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107 } |
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108 |
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109 size_t partial_array_length() const { |
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110 return field_partial_array_length::decode(_entry); |
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111 } |
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112 |
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113 uintptr_t object_address() const { |
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114 return field_object_address::decode(_entry); |
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115 } |
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116 }; |
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117 |
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118 #endif // SHARE_GC_Z_ZMARKSTACKENTRY_HPP |