1 /* 2 * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_CI_CIFIELD_HPP 26 #define SHARE_CI_CIFIELD_HPP 27 28 #include "ci/ciClassList.hpp" 29 #include "ci/ciConstant.hpp" 30 #include "ci/ciFlags.hpp" 31 #include "ci/ciInstance.hpp" 32 #include "ci/ciUtilities.hpp" 33 34 // ciField 35 // 36 // This class represents the result of a field lookup in the VM. 37 // The lookup may not succeed, in which case the information in 38 // the ciField will be incomplete. 39 class ciField : public ResourceObj { 40 CI_PACKAGE_ACCESS 41 friend class ciEnv; 42 friend class ciInstanceKlass; 43 44 private: 45 ciFlags _flags; 46 ciInstanceKlass* _holder; 47 ciSymbol* _name; 48 ciSymbol* _signature; 49 ciType* _type; 50 int _offset; 51 bool _is_constant; 52 bool _is_flattened; 53 bool _is_flattenable; 54 ciMethod* _known_to_link_with_put; 55 ciInstanceKlass* _known_to_link_with_get; 56 ciConstant _constant_value; 57 58 ciType* compute_type(); 59 ciType* compute_type_impl(); 60 61 ciField(ciInstanceKlass* klass, int index); 62 ciField(fieldDescriptor* fd); 63 ciField(ciField* field, ciInstanceKlass* holder, int offset, bool is_final); 64 65 // shared constructor code 66 void initialize_from(fieldDescriptor* fd); 67 68 public: 69 ciFlags flags() const { return _flags; } 70 71 // Of which klass is this field a member? 72 // 73 // Usage note: the declared holder of a field is the class 74 // referenced by name in the bytecodes. The canonical holder 75 // is the most general class which holds the field. This 76 // method returns the canonical holder. The declared holder 77 // can be accessed via a method in ciBytecodeStream. 78 // 79 // Ex. 80 // class A { 81 // public int f = 7; 82 // } 83 // class B extends A { 84 // public void test() { 85 // System.out.println(f); 86 // } 87 // } 88 // 89 // A java compiler is permitted to compile the access to 90 // field f as: 91 // 92 // getfield B.f 93 // 94 // In that case the declared holder of f would be B and 95 // the canonical holder of f would be A. 96 ciInstanceKlass* holder() const { return _holder; } 97 98 // Name of this field? 99 ciSymbol* name() const { return _name; } 100 101 // Signature of this field? 102 ciSymbol* signature() const { return _signature; } 103 104 // Of what type is this field? 105 ciType* type() { return (_type == NULL) ? compute_type() : _type; } 106 107 // How is this field actually stored in memory? 108 BasicType layout_type() { return type2field[type()->basic_type()]; } 109 110 // How big is this field in memory? 111 int size_in_bytes() { return type2aelembytes(layout_type()); } 112 113 // What is the offset of this field? 114 int offset() const { 115 assert(_offset >= 1, "illegal call to offset()"); 116 return _offset; 117 } 118 119 // Same question, explicit units. (Fields are aligned to the byte level.) 120 int offset_in_bytes() const { 121 return offset(); 122 } 123 124 // Is this field shared? 125 bool is_shared() { 126 // non-static fields of shared holders are cached 127 return _holder->is_shared() && !is_static(); 128 } 129 130 // Is this field a constant? 131 // 132 // Clarification: A field is considered constant if: 133 // 1. The field is both static and final 134 // 2. The field is not one of the special static/final 135 // non-constant fields. These are java.lang.System.in 136 // and java.lang.System.out. Abomination. 137 // 138 // A field is also considered constant if 139 // - it is marked @Stable and is non-null (or non-zero, if a primitive) or 140 // - it is trusted or 141 // - it is the target field of a CallSite object. 142 // 143 // See ciField::initialize_from() for more details. 144 // 145 // A user should also check the field value (constant_value().is_valid()), since 146 // constant fields of non-initialized classes don't have values yet. 147 bool is_constant() const { return _is_constant; } 148 149 // Get the constant value of the static field. 150 ciConstant constant_value(); 151 152 bool is_static_constant() { 153 return is_static() && is_constant() && constant_value().is_valid(); 154 } 155 156 // Get the constant value of non-static final field in the given 157 // object. 158 ciConstant constant_value_of(ciObject* object); 159 160 // Check for link time errors. Accessing a field from a 161 // certain method via a certain bytecode may or may not be legal. 162 // This call checks to see if an exception may be raised by 163 // an access of this field. 164 // 165 // Usage note: if the same field is accessed multiple times 166 // in the same compilation, will_link will need to be checked 167 // at each point of access. 168 bool will_link(ciMethod* accessing_method, 169 Bytecodes::Code bc); 170 171 // Java access flags 172 bool is_public () const { return flags().is_public(); } 173 bool is_private () const { return flags().is_private(); } 174 bool is_protected () const { return flags().is_protected(); } 175 bool is_static () const { return flags().is_static(); } 176 bool is_final () const { return flags().is_final(); } 177 bool is_stable () const { return flags().is_stable(); } 178 bool is_volatile () const { return flags().is_volatile(); } 179 bool is_transient () const { return flags().is_transient(); } 180 bool is_flattened () const { return _is_flattened; } 181 bool is_flattenable () const { return _is_flattenable; } 182 183 // The field is modified outside of instance initializer methods 184 // (or class/initializer methods if the field is static). 185 bool has_initialized_final_update() const { return flags().has_initialized_final_update(); } 186 187 bool is_call_site_target() { 188 ciInstanceKlass* callsite_klass = CURRENT_ENV->CallSite_klass(); 189 if (callsite_klass == NULL) 190 return false; 191 return (holder()->is_subclass_of(callsite_klass) && (name() == ciSymbol::target_name())); 192 } 193 194 bool is_autobox_cache() { 195 ciSymbol* klass_name = holder()->name(); 196 return (name() == ciSymbol::cache_field_name() && 197 holder()->uses_default_loader() && 198 (klass_name == ciSymbol::java_lang_Character_CharacterCache() || 199 klass_name == ciSymbol::java_lang_Byte_ByteCache() || 200 klass_name == ciSymbol::java_lang_Short_ShortCache() || 201 klass_name == ciSymbol::java_lang_Integer_IntegerCache() || 202 klass_name == ciSymbol::java_lang_Long_LongCache())); 203 } 204 205 bool is_q_type() const { 206 // Cannot use (type()->basic_type() == T_VALUETYPE) -- if the class is not loaded, 207 // type() is an unloaded ciInstanceKlass! 208 return signature()->char_at(0) == 'Q'; 209 } 210 211 // Debugging output 212 void print(); 213 void print_name_on(outputStream* st); 214 }; 215 216 #endif // SHARE_CI_CIFIELD_HPP