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1 /* |
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2 * Copyright (c) 2005, 2012, 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 |
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25 #ifndef SHARE_VM_CODE_DEPENDENCIES_HPP |
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26 #define SHARE_VM_CODE_DEPENDENCIES_HPP |
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27 |
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28 #include "ci/ciCallSite.hpp" |
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29 #include "ci/ciKlass.hpp" |
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30 #include "ci/ciMethodHandle.hpp" |
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31 #include "classfile/systemDictionary.hpp" |
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32 #include "code/compressedStream.hpp" |
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33 #include "code/nmethod.hpp" |
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34 #include "utilities/growableArray.hpp" |
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35 |
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36 //** Dependencies represent assertions (approximate invariants) within |
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37 // the runtime system, e.g. class hierarchy changes. An example is an |
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38 // assertion that a given method is not overridden; another example is |
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39 // that a type has only one concrete subtype. Compiled code which |
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40 // relies on such assertions must be discarded if they are overturned |
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41 // by changes in the runtime system. We can think of these assertions |
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42 // as approximate invariants, because we expect them to be overturned |
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43 // very infrequently. We are willing to perform expensive recovery |
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44 // operations when they are overturned. The benefit, of course, is |
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45 // performing optimistic optimizations (!) on the object code. |
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46 // |
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47 // Changes in the class hierarchy due to dynamic linking or |
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48 // class evolution can violate dependencies. There is enough |
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49 // indexing between classes and nmethods to make dependency |
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50 // checking reasonably efficient. |
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51 |
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52 class ciEnv; |
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53 class nmethod; |
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54 class OopRecorder; |
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55 class xmlStream; |
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56 class CompileLog; |
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57 class DepChange; |
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58 class KlassDepChange; |
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59 class CallSiteDepChange; |
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60 class No_Safepoint_Verifier; |
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61 |
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62 class Dependencies: public ResourceObj { |
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63 public: |
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64 // Note: In the comments on dependency types, most uses of the terms |
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65 // subtype and supertype are used in a "non-strict" or "inclusive" |
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66 // sense, and are starred to remind the reader of this fact. |
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67 // Strict uses of the terms use the word "proper". |
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68 // |
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69 // Specifically, every class is its own subtype* and supertype*. |
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70 // (This trick is easier than continually saying things like "Y is a |
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71 // subtype of X or X itself".) |
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72 // |
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73 // Sometimes we write X > Y to mean X is a proper supertype of Y. |
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74 // The notation X > {Y, Z} means X has proper subtypes Y, Z. |
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75 // The notation X.m > Y means that Y inherits m from X, while |
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76 // X.m > Y.m means Y overrides X.m. A star denotes abstractness, |
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77 // as *I > A, meaning (abstract) interface I is a super type of A, |
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78 // or A.*m > B.m, meaning B.m implements abstract method A.m. |
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79 // |
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80 // In this module, the terms "subtype" and "supertype" refer to |
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81 // Java-level reference type conversions, as detected by |
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82 // "instanceof" and performed by "checkcast" operations. The method |
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83 // Klass::is_subtype_of tests these relations. Note that "subtype" |
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84 // is richer than "subclass" (as tested by Klass::is_subclass_of), |
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85 // since it takes account of relations involving interface and array |
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86 // types. |
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87 // |
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88 // To avoid needless complexity, dependencies involving array types |
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89 // are not accepted. If you need to make an assertion about an |
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90 // array type, make the assertion about its corresponding element |
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91 // types. Any assertion that might change about an array type can |
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92 // be converted to an assertion about its element type. |
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93 // |
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94 // Most dependencies are evaluated over a "context type" CX, which |
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95 // stands for the set Subtypes(CX) of every Java type that is a subtype* |
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96 // of CX. When the system loads a new class or interface N, it is |
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97 // responsible for re-evaluating changed dependencies whose context |
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98 // type now includes N, that is, all super types of N. |
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99 // |
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100 enum DepType { |
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101 end_marker = 0, |
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102 |
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103 // An 'evol' dependency simply notes that the contents of the |
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104 // method were used. If it evolves (is replaced), the nmethod |
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105 // must be recompiled. No other dependencies are implied. |
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106 evol_method, |
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107 FIRST_TYPE = evol_method, |
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108 |
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109 // A context type CX is a leaf it if has no proper subtype. |
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110 leaf_type, |
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111 |
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112 // An abstract class CX has exactly one concrete subtype CC. |
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113 abstract_with_unique_concrete_subtype, |
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114 |
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115 // The type CX is purely abstract, with no concrete subtype* at all. |
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116 abstract_with_no_concrete_subtype, |
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117 |
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118 // The concrete CX is free of concrete proper subtypes. |
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119 concrete_with_no_concrete_subtype, |
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120 |
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121 // Given a method M1 and a context class CX, the set MM(CX, M1) of |
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122 // "concrete matching methods" in CX of M1 is the set of every |
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123 // concrete M2 for which it is possible to create an invokevirtual |
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124 // or invokeinterface call site that can reach either M1 or M2. |
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125 // That is, M1 and M2 share a name, signature, and vtable index. |
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126 // We wish to notice when the set MM(CX, M1) is just {M1}, or |
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127 // perhaps a set of two {M1,M2}, and issue dependencies on this. |
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128 |
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129 // The set MM(CX, M1) can be computed by starting with any matching |
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130 // concrete M2 that is inherited into CX, and then walking the |
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131 // subtypes* of CX looking for concrete definitions. |
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132 |
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133 // The parameters to this dependency are the method M1 and the |
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134 // context class CX. M1 must be either inherited in CX or defined |
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135 // in a subtype* of CX. It asserts that MM(CX, M1) is no greater |
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136 // than {M1}. |
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137 unique_concrete_method, // one unique concrete method under CX |
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138 |
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139 // An "exclusive" assertion concerns two methods or subtypes, and |
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140 // declares that there are at most two (or perhaps later N>2) |
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141 // specific items that jointly satisfy the restriction. |
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142 // We list all items explicitly rather than just giving their |
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143 // count, for robustness in the face of complex schema changes. |
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144 |
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145 // A context class CX (which may be either abstract or concrete) |
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146 // has two exclusive concrete subtypes* C1, C2 if every concrete |
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147 // subtype* of CX is either C1 or C2. Note that if neither C1 or C2 |
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148 // are equal to CX, then CX itself must be abstract. But it is |
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149 // also possible (for example) that C1 is CX (a concrete class) |
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150 // and C2 is a proper subtype of C1. |
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151 abstract_with_exclusive_concrete_subtypes_2, |
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152 |
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153 // This dependency asserts that MM(CX, M1) is no greater than {M1,M2}. |
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154 exclusive_concrete_methods_2, |
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155 |
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156 // This dependency asserts that no instances of class or it's |
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157 // subclasses require finalization registration. |
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158 no_finalizable_subclasses, |
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159 |
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160 // This dependency asserts when the CallSite.target value changed. |
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161 call_site_target_value, |
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162 |
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163 TYPE_LIMIT |
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164 }; |
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165 enum { |
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166 LG2_TYPE_LIMIT = 4, // assert(TYPE_LIMIT <= (1<<LG2_TYPE_LIMIT)) |
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167 |
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168 // handy categorizations of dependency types: |
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169 all_types = ((1 << TYPE_LIMIT) - 1) & ((-1) << FIRST_TYPE), |
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170 |
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171 non_klass_types = (1 << call_site_target_value), |
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172 klass_types = all_types & ~non_klass_types, |
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173 |
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174 non_ctxk_types = (1 << evol_method), |
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175 implicit_ctxk_types = (1 << call_site_target_value), |
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176 explicit_ctxk_types = all_types & ~(non_ctxk_types | implicit_ctxk_types), |
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177 |
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178 max_arg_count = 3, // current maximum number of arguments (incl. ctxk) |
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179 |
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180 // A "context type" is a class or interface that |
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181 // provides context for evaluating a dependency. |
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182 // When present, it is one of the arguments (dep_context_arg). |
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183 // |
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184 // If a dependency does not have a context type, there is a |
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185 // default context, depending on the type of the dependency. |
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186 // This bit signals that a default context has been compressed away. |
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187 default_context_type_bit = (1<<LG2_TYPE_LIMIT) |
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188 }; |
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189 |
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190 static const char* dep_name(DepType dept); |
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191 static int dep_args(DepType dept); |
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192 |
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193 static bool is_klass_type( DepType dept) { return dept_in_mask(dept, klass_types ); } |
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194 |
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195 static bool has_explicit_context_arg(DepType dept) { return dept_in_mask(dept, explicit_ctxk_types); } |
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196 static bool has_implicit_context_arg(DepType dept) { return dept_in_mask(dept, implicit_ctxk_types); } |
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197 |
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198 static int dep_context_arg(DepType dept) { return has_explicit_context_arg(dept) ? 0 : -1; } |
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199 static int dep_implicit_context_arg(DepType dept) { return has_implicit_context_arg(dept) ? 0 : -1; } |
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200 |
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201 static void check_valid_dependency_type(DepType dept); |
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202 |
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203 private: |
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204 // State for writing a new set of dependencies: |
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205 GrowableArray<int>* _dep_seen; // (seen[h->ident] & (1<<dept)) |
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206 GrowableArray<ciBaseObject*>* _deps[TYPE_LIMIT]; |
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207 |
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208 static const char* _dep_name[TYPE_LIMIT]; |
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209 static int _dep_args[TYPE_LIMIT]; |
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210 |
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211 static bool dept_in_mask(DepType dept, int mask) { |
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212 return (int)dept >= 0 && dept < TYPE_LIMIT && ((1<<dept) & mask) != 0; |
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213 } |
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214 |
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215 bool note_dep_seen(int dept, ciBaseObject* x) { |
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216 assert(dept < BitsPerInt, "oob"); |
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217 int x_id = x->ident(); |
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218 assert(_dep_seen != NULL, "deps must be writable"); |
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219 int seen = _dep_seen->at_grow(x_id, 0); |
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220 _dep_seen->at_put(x_id, seen | (1<<dept)); |
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221 // return true if we've already seen dept/x |
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222 return (seen & (1<<dept)) != 0; |
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223 } |
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224 |
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225 bool maybe_merge_ctxk(GrowableArray<ciBaseObject*>* deps, |
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226 int ctxk_i, ciKlass* ctxk); |
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227 |
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228 void sort_all_deps(); |
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229 size_t estimate_size_in_bytes(); |
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230 |
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231 // Initialize _deps, etc. |
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232 void initialize(ciEnv* env); |
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233 |
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234 // State for making a new set of dependencies: |
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235 OopRecorder* _oop_recorder; |
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236 |
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237 // Logging support |
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238 CompileLog* _log; |
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239 |
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240 address _content_bytes; // everything but the oop references, encoded |
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241 size_t _size_in_bytes; |
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242 |
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243 public: |
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244 // Make a new empty dependencies set. |
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245 Dependencies(ciEnv* env) { |
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246 initialize(env); |
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247 } |
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248 |
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249 private: |
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250 // Check for a valid context type. |
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251 // Enforce the restriction against array types. |
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252 static void check_ctxk(ciKlass* ctxk) { |
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253 assert(ctxk->is_instance_klass(), "java types only"); |
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254 } |
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255 static void check_ctxk_concrete(ciKlass* ctxk) { |
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256 assert(is_concrete_klass(ctxk->as_instance_klass()), "must be concrete"); |
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257 } |
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258 static void check_ctxk_abstract(ciKlass* ctxk) { |
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259 check_ctxk(ctxk); |
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260 assert(!is_concrete_klass(ctxk->as_instance_klass()), "must be abstract"); |
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261 } |
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262 |
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263 void assert_common_1(DepType dept, ciBaseObject* x); |
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264 void assert_common_2(DepType dept, ciBaseObject* x0, ciBaseObject* x1); |
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265 void assert_common_3(DepType dept, ciKlass* ctxk, ciBaseObject* x1, ciBaseObject* x2); |
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266 |
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267 public: |
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268 // Adding assertions to a new dependency set at compile time: |
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269 void assert_evol_method(ciMethod* m); |
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270 void assert_leaf_type(ciKlass* ctxk); |
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271 void assert_abstract_with_unique_concrete_subtype(ciKlass* ctxk, ciKlass* conck); |
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272 void assert_abstract_with_no_concrete_subtype(ciKlass* ctxk); |
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273 void assert_concrete_with_no_concrete_subtype(ciKlass* ctxk); |
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274 void assert_unique_concrete_method(ciKlass* ctxk, ciMethod* uniqm); |
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275 void assert_abstract_with_exclusive_concrete_subtypes(ciKlass* ctxk, ciKlass* k1, ciKlass* k2); |
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276 void assert_exclusive_concrete_methods(ciKlass* ctxk, ciMethod* m1, ciMethod* m2); |
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277 void assert_has_no_finalizable_subclasses(ciKlass* ctxk); |
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278 void assert_call_site_target_value(ciCallSite* call_site, ciMethodHandle* method_handle); |
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279 |
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280 // Define whether a given method or type is concrete. |
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281 // These methods define the term "concrete" as used in this module. |
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282 // For this module, an "abstract" class is one which is non-concrete. |
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283 // |
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284 // Future optimizations may allow some classes to remain |
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285 // non-concrete until their first instantiation, and allow some |
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286 // methods to remain non-concrete until their first invocation. |
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287 // In that case, there would be a middle ground between concrete |
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288 // and abstract (as defined by the Java language and VM). |
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289 static bool is_concrete_klass(Klass* k); // k is instantiable |
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290 static bool is_concrete_method(Method* m); // m is invocable |
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291 static Klass* find_finalizable_subclass(Klass* k); |
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292 |
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293 // These versions of the concreteness queries work through the CI. |
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294 // The CI versions are allowed to skew sometimes from the VM |
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295 // (oop-based) versions. The cost of such a difference is a |
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296 // (safely) aborted compilation, or a deoptimization, or a missed |
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297 // optimization opportunity. |
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298 // |
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299 // In order to prevent spurious assertions, query results must |
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300 // remain stable within any single ciEnv instance. (I.e., they must |
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301 // not go back into the VM to get their value; they must cache the |
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302 // bit in the CI, either eagerly or lazily.) |
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303 static bool is_concrete_klass(ciInstanceKlass* k); // k appears instantiable |
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304 static bool is_concrete_method(ciMethod* m); // m appears invocable |
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305 static bool has_finalizable_subclass(ciInstanceKlass* k); |
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306 |
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307 // As a general rule, it is OK to compile under the assumption that |
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308 // a given type or method is concrete, even if it at some future |
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309 // point becomes abstract. So dependency checking is one-sided, in |
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310 // that it permits supposedly concrete classes or methods to turn up |
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311 // as really abstract. (This shouldn't happen, except during class |
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312 // evolution, but that's the logic of the checking.) However, if a |
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313 // supposedly abstract class or method suddenly becomes concrete, a |
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314 // dependency on it must fail. |
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315 |
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316 // Checking old assertions at run-time (in the VM only): |
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317 static Klass* check_evol_method(Method* m); |
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318 static Klass* check_leaf_type(Klass* ctxk); |
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319 static Klass* check_abstract_with_unique_concrete_subtype(Klass* ctxk, Klass* conck, |
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320 KlassDepChange* changes = NULL); |
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321 static Klass* check_abstract_with_no_concrete_subtype(Klass* ctxk, |
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322 KlassDepChange* changes = NULL); |
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323 static Klass* check_concrete_with_no_concrete_subtype(Klass* ctxk, |
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324 KlassDepChange* changes = NULL); |
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325 static Klass* check_unique_concrete_method(Klass* ctxk, Method* uniqm, |
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326 KlassDepChange* changes = NULL); |
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327 static Klass* check_abstract_with_exclusive_concrete_subtypes(Klass* ctxk, Klass* k1, Klass* k2, |
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328 KlassDepChange* changes = NULL); |
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329 static Klass* check_exclusive_concrete_methods(Klass* ctxk, Method* m1, Method* m2, |
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330 KlassDepChange* changes = NULL); |
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331 static Klass* check_has_no_finalizable_subclasses(Klass* ctxk, KlassDepChange* changes = NULL); |
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332 static Klass* check_call_site_target_value(oop call_site, oop method_handle, CallSiteDepChange* changes = NULL); |
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333 // A returned Klass* is NULL if the dependency assertion is still |
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334 // valid. A non-NULL Klass* is a 'witness' to the assertion |
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335 // failure, a point in the class hierarchy where the assertion has |
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336 // been proven false. For example, if check_leaf_type returns |
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337 // non-NULL, the value is a subtype of the supposed leaf type. This |
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338 // witness value may be useful for logging the dependency failure. |
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339 // Note that, when a dependency fails, there may be several possible |
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340 // witnesses to the failure. The value returned from the check_foo |
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341 // method is chosen arbitrarily. |
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342 |
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343 // The 'changes' value, if non-null, requests a limited spot-check |
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344 // near the indicated recent changes in the class hierarchy. |
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345 // It is used by DepStream::spot_check_dependency_at. |
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346 |
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347 // Detecting possible new assertions: |
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348 static Klass* find_unique_concrete_subtype(Klass* ctxk); |
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349 static Method* find_unique_concrete_method(Klass* ctxk, Method* m); |
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350 static int find_exclusive_concrete_subtypes(Klass* ctxk, int klen, Klass* k[]); |
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351 static int find_exclusive_concrete_methods(Klass* ctxk, int mlen, Method* m[]); |
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352 |
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353 // Create the encoding which will be stored in an nmethod. |
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354 void encode_content_bytes(); |
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355 |
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356 address content_bytes() { |
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357 assert(_content_bytes != NULL, "encode it first"); |
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358 return _content_bytes; |
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359 } |
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360 size_t size_in_bytes() { |
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361 assert(_content_bytes != NULL, "encode it first"); |
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362 return _size_in_bytes; |
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363 } |
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364 |
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365 OopRecorder* oop_recorder() { return _oop_recorder; } |
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366 CompileLog* log() { return _log; } |
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367 |
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368 void copy_to(nmethod* nm); |
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369 |
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370 void log_all_dependencies(); |
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371 void log_dependency(DepType dept, int nargs, ciBaseObject* args[]) { |
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372 write_dependency_to(log(), dept, nargs, args); |
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373 } |
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374 void log_dependency(DepType dept, |
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375 ciBaseObject* x0, |
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376 ciBaseObject* x1 = NULL, |
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377 ciBaseObject* x2 = NULL) { |
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378 if (log() == NULL) return; |
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379 ciBaseObject* args[max_arg_count]; |
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380 args[0] = x0; |
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381 args[1] = x1; |
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382 args[2] = x2; |
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383 assert(2 < max_arg_count, ""); |
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384 log_dependency(dept, dep_args(dept), args); |
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385 } |
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386 |
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387 class DepArgument : public ResourceObj { |
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388 private: |
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389 bool _is_oop; |
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390 bool _valid; |
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391 void* _value; |
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392 public: |
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393 DepArgument() : _is_oop(false), _value(NULL), _valid(false) {} |
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394 DepArgument(oop v): _is_oop(true), _value(v), _valid(true) {} |
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395 DepArgument(Metadata* v): _is_oop(false), _value(v), _valid(true) {} |
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396 |
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397 bool is_null() const { return _value == NULL; } |
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398 bool is_oop() const { return _is_oop; } |
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399 bool is_metadata() const { return !_is_oop; } |
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400 bool is_klass() const { return is_metadata() && metadata_value()->is_klass(); } |
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401 bool is_method() const { return is_metadata() && metadata_value()->is_method(); } |
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402 |
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403 oop oop_value() const { assert(_is_oop && _valid, "must be"); return (oop) _value; } |
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404 Metadata* metadata_value() const { assert(!_is_oop && _valid, "must be"); return (Metadata*) _value; } |
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405 }; |
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406 |
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407 static void write_dependency_to(CompileLog* log, |
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408 DepType dept, |
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409 int nargs, ciBaseObject* args[], |
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410 Klass* witness = NULL); |
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411 static void write_dependency_to(CompileLog* log, |
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412 DepType dept, |
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413 int nargs, DepArgument args[], |
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414 Klass* witness = NULL); |
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415 static void write_dependency_to(xmlStream* xtty, |
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416 DepType dept, |
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417 int nargs, DepArgument args[], |
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418 Klass* witness = NULL); |
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419 static void print_dependency(DepType dept, |
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420 int nargs, DepArgument args[], |
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421 Klass* witness = NULL); |
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422 |
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423 private: |
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424 // helper for encoding common context types as zero: |
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425 static ciKlass* ctxk_encoded_as_null(DepType dept, ciBaseObject* x); |
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426 |
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427 static Klass* ctxk_encoded_as_null(DepType dept, Metadata* x); |
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428 |
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429 public: |
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430 // Use this to iterate over an nmethod's dependency set. |
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431 // Works on new and old dependency sets. |
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432 // Usage: |
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433 // |
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434 // ; |
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435 // Dependencies::DepType dept; |
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436 // for (Dependencies::DepStream deps(nm); deps.next(); ) { |
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437 // ... |
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438 // } |
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439 // |
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440 // The caller must be in the VM, since oops are not wrapped in handles. |
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441 class DepStream { |
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442 private: |
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443 nmethod* _code; // null if in a compiler thread |
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444 Dependencies* _deps; // null if not in a compiler thread |
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445 CompressedReadStream _bytes; |
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446 #ifdef ASSERT |
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447 size_t _byte_limit; |
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448 #endif |
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449 |
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450 // iteration variables: |
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451 DepType _type; |
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452 int _xi[max_arg_count+1]; |
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453 |
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454 void initial_asserts(size_t byte_limit) NOT_DEBUG({}); |
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455 |
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456 inline Metadata* recorded_metadata_at(int i); |
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457 inline oop recorded_oop_at(int i); |
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458 |
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459 Klass* check_klass_dependency(KlassDepChange* changes); |
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460 Klass* check_call_site_dependency(CallSiteDepChange* changes); |
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461 |
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462 void trace_and_log_witness(Klass* witness); |
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463 |
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464 public: |
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465 DepStream(Dependencies* deps) |
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466 : _deps(deps), |
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467 _code(NULL), |
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468 _bytes(deps->content_bytes()) |
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469 { |
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470 initial_asserts(deps->size_in_bytes()); |
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471 } |
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472 DepStream(nmethod* code) |
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473 : _deps(NULL), |
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474 _code(code), |
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475 _bytes(code->dependencies_begin()) |
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476 { |
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477 initial_asserts(code->dependencies_size()); |
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478 } |
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479 |
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480 bool next(); |
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481 |
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482 DepType type() { return _type; } |
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483 int argument_count() { return dep_args(type()); } |
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484 int argument_index(int i) { assert(0 <= i && i < argument_count(), "oob"); |
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485 return _xi[i]; } |
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486 Metadata* argument(int i); // => recorded_oop_at(argument_index(i)) |
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487 oop argument_oop(int i); // => recorded_oop_at(argument_index(i)) |
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488 Klass* context_type(); |
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489 |
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490 bool is_klass_type() { return Dependencies::is_klass_type(type()); } |
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491 |
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492 Method* method_argument(int i) { |
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493 Metadata* x = argument(i); |
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494 assert(x->is_method(), "type"); |
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495 return (Method*) x; |
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496 } |
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497 Klass* type_argument(int i) { |
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498 Metadata* x = argument(i); |
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499 assert(x->is_klass(), "type"); |
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500 return (Klass*) x; |
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501 } |
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502 |
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503 // The point of the whole exercise: Is this dep still OK? |
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504 Klass* check_dependency() { |
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505 Klass* result = check_klass_dependency(NULL); |
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506 if (result != NULL) return result; |
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507 return check_call_site_dependency(NULL); |
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508 } |
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509 |
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510 // A lighter version: Checks only around recent changes in a class |
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511 // hierarchy. (See Universe::flush_dependents_on.) |
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512 Klass* spot_check_dependency_at(DepChange& changes); |
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513 |
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514 // Log the current dependency to xtty or compilation log. |
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515 void log_dependency(Klass* witness = NULL); |
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516 |
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517 // Print the current dependency to tty. |
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518 void print_dependency(Klass* witness = NULL, bool verbose = false); |
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519 }; |
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520 friend class Dependencies::DepStream; |
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521 |
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522 static void print_statistics() PRODUCT_RETURN; |
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523 }; |
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524 |
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525 |
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526 // Every particular DepChange is a sub-class of this class. |
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527 class DepChange : public StackObj { |
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528 public: |
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529 // What kind of DepChange is this? |
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530 virtual bool is_klass_change() const { return false; } |
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531 virtual bool is_call_site_change() const { return false; } |
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532 |
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533 // Subclass casting with assertions. |
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534 KlassDepChange* as_klass_change() { |
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535 assert(is_klass_change(), "bad cast"); |
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536 return (KlassDepChange*) this; |
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537 } |
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538 CallSiteDepChange* as_call_site_change() { |
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539 assert(is_call_site_change(), "bad cast"); |
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540 return (CallSiteDepChange*) this; |
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541 } |
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542 |
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543 void print(); |
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544 |
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545 public: |
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546 enum ChangeType { |
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547 NO_CHANGE = 0, // an uninvolved klass |
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548 Change_new_type, // a newly loaded type |
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549 Change_new_sub, // a super with a new subtype |
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550 Change_new_impl, // an interface with a new implementation |
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551 CHANGE_LIMIT, |
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552 Start_Klass = CHANGE_LIMIT // internal indicator for ContextStream |
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553 }; |
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554 |
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555 // Usage: |
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556 // for (DepChange::ContextStream str(changes); str.next(); ) { |
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557 // Klass* k = str.klass(); |
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558 // switch (str.change_type()) { |
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559 // ... |
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560 // } |
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561 // } |
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562 class ContextStream : public StackObj { |
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563 private: |
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564 DepChange& _changes; |
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565 friend class DepChange; |
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566 |
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567 // iteration variables: |
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568 ChangeType _change_type; |
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569 Klass* _klass; |
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570 Array<Klass*>* _ti_base; // i.e., transitive_interfaces |
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571 int _ti_index; |
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572 int _ti_limit; |
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573 |
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574 // start at the beginning: |
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575 void start(); |
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576 |
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577 public: |
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578 ContextStream(DepChange& changes) |
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579 : _changes(changes) |
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580 { start(); } |
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581 |
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582 ContextStream(DepChange& changes, No_Safepoint_Verifier& nsv) |
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583 : _changes(changes) |
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584 // the nsv argument makes it safe to hold oops like _klass |
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585 { start(); } |
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586 |
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587 bool next(); |
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588 |
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589 ChangeType change_type() { return _change_type; } |
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590 Klass* klass() { return _klass; } |
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591 }; |
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592 friend class DepChange::ContextStream; |
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593 }; |
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594 |
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595 |
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596 // A class hierarchy change coming through the VM (under the Compile_lock). |
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597 // The change is structured as a single new type with any number of supers |
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598 // and implemented interface types. Other than the new type, any of the |
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599 // super types can be context types for a relevant dependency, which the |
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600 // new type could invalidate. |
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601 class KlassDepChange : public DepChange { |
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602 private: |
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603 // each change set is rooted in exactly one new type (at present): |
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604 KlassHandle _new_type; |
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605 |
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606 void initialize(); |
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607 |
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608 public: |
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609 // notes the new type, marks it and all its super-types |
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610 KlassDepChange(KlassHandle new_type) |
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611 : _new_type(new_type) |
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612 { |
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613 initialize(); |
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614 } |
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615 |
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616 // cleans up the marks |
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617 ~KlassDepChange(); |
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618 |
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619 // What kind of DepChange is this? |
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620 virtual bool is_klass_change() const { return true; } |
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621 |
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622 Klass* new_type() { return _new_type(); } |
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623 |
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624 // involves_context(k) is true if k is new_type or any of the super types |
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625 bool involves_context(Klass* k); |
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626 }; |
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627 |
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628 |
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629 // A CallSite has changed its target. |
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630 class CallSiteDepChange : public DepChange { |
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631 private: |
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632 Handle _call_site; |
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633 Handle _method_handle; |
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634 |
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635 public: |
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636 CallSiteDepChange(Handle call_site, Handle method_handle) |
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637 : _call_site(call_site), |
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638 _method_handle(method_handle) |
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639 { |
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640 assert(_call_site() ->is_a(SystemDictionary::CallSite_klass()), "must be"); |
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641 assert(_method_handle()->is_a(SystemDictionary::MethodHandle_klass()), "must be"); |
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642 } |
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643 |
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644 // What kind of DepChange is this? |
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645 virtual bool is_call_site_change() const { return true; } |
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646 |
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647 oop call_site() const { return _call_site(); } |
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648 oop method_handle() const { return _method_handle(); } |
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649 }; |
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650 |
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651 #endif // SHARE_VM_CODE_DEPENDENCIES_HPP |