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 ciMethod* _known_to_link_with_put; 53 ciInstanceKlass* _known_to_link_with_get; 54 ciConstant _constant_value; 55 56 ciType* compute_type(); 57 ciType* compute_type_impl(); 58 59 ciField(ciInstanceKlass* klass, int index); 60 ciField(fieldDescriptor* fd); 61 62 // shared constructor code 63 void initialize_from(fieldDescriptor* fd); 64 65 public: flags() const66 ciFlags flags() const { return _flags; } 67 68 // Of which klass is this field a member? 69 // 70 // Usage note: the declared holder of a field is the class 71 // referenced by name in the bytecodes. The canonical holder 72 // is the most general class which holds the field. This 73 // method returns the canonical holder. The declared holder 74 // can be accessed via a method in ciBytecodeStream. 75 // 76 // Ex. 77 // class A { 78 // public int f = 7; 79 // } 80 // class B extends A { 81 // public void test() { 82 // System.out.println(f); 83 // } 84 // } 85 // 86 // A java compiler is permitted to compile the access to 87 // field f as: 88 // 89 // getfield B.f 90 // 91 // In that case the declared holder of f would be B and 92 // the canonical holder of f would be A. holder() const93 ciInstanceKlass* holder() const { return _holder; } 94 95 // Name of this field? name() const96 ciSymbol* name() const { return _name; } 97 98 // Signature of this field? signature() const99 ciSymbol* signature() const { return _signature; } 100 101 // Of what type is this field? type()102 ciType* type() { return (_type == NULL) ? compute_type() : _type; } 103 104 // How is this field actually stored in memory? layout_type()105 BasicType layout_type() { return type2field[(_type == NULL) ? T_OBJECT : _type->basic_type()]; } 106 107 // How big is this field in memory? size_in_bytes()108 int size_in_bytes() { return type2aelembytes(layout_type()); } 109 110 // What is the offset of this field? offset() const111 int offset() const { 112 assert(_offset >= 1, "illegal call to offset()"); 113 return _offset; 114 } 115 116 // Same question, explicit units. (Fields are aligned to the byte level.) offset_in_bytes() const117 int offset_in_bytes() const { 118 return offset(); 119 } 120 121 // Is this field shared? is_shared()122 bool is_shared() { 123 // non-static fields of shared holders are cached 124 return _holder->is_shared() && !is_static(); 125 } 126 127 // Is this field a constant? 128 // 129 // Clarification: A field is considered constant if: 130 // 1. The field is both static and final 131 // 2. The field is not one of the special static/final 132 // non-constant fields. These are java.lang.System.in 133 // and java.lang.System.out. Abomination. 134 // 135 // A field is also considered constant if 136 // - it is marked @Stable and is non-null (or non-zero, if a primitive) or 137 // - it is trusted or 138 // - it is the target field of a CallSite object. 139 // 140 // See ciField::initialize_from() for more details. 141 // 142 // A user should also check the field value (constant_value().is_valid()), since 143 // constant fields of non-initialized classes don't have values yet. is_constant() const144 bool is_constant() const { return _is_constant; } 145 146 // Get the constant value of the static field. 147 ciConstant constant_value(); 148 is_static_constant()149 bool is_static_constant() { 150 return is_static() && is_constant() && constant_value().is_valid(); 151 } 152 153 // Get the constant value of non-static final field in the given 154 // object. 155 ciConstant constant_value_of(ciObject* object); 156 157 // Check for link time errors. Accessing a field from a 158 // certain method via a certain bytecode may or may not be legal. 159 // This call checks to see if an exception may be raised by 160 // an access of this field. 161 // 162 // Usage note: if the same field is accessed multiple times 163 // in the same compilation, will_link will need to be checked 164 // at each point of access. 165 bool will_link(ciMethod* accessing_method, 166 Bytecodes::Code bc); 167 168 // Java access flags is_public() const169 bool is_public () const { return flags().is_public(); } is_private() const170 bool is_private () const { return flags().is_private(); } is_protected() const171 bool is_protected () const { return flags().is_protected(); } is_static() const172 bool is_static () const { return flags().is_static(); } is_final() const173 bool is_final () const { return flags().is_final(); } is_stable() const174 bool is_stable () const { return flags().is_stable(); } is_volatile() const175 bool is_volatile () const { return flags().is_volatile(); } is_transient() const176 bool is_transient () const { return flags().is_transient(); } 177 // The field is modified outside of instance initializer methods 178 // (or class/initializer methods if the field is static). has_initialized_final_update() const179 bool has_initialized_final_update() const { return flags().has_initialized_final_update(); } 180 is_call_site_target()181 bool is_call_site_target() { 182 ciInstanceKlass* callsite_klass = CURRENT_ENV->CallSite_klass(); 183 if (callsite_klass == NULL) 184 return false; 185 return (holder()->is_subclass_of(callsite_klass) && (name() == ciSymbol::target_name())); 186 } 187 is_autobox_cache()188 bool is_autobox_cache() { 189 ciSymbol* klass_name = holder()->name(); 190 return (name() == ciSymbol::cache_field_name() && 191 holder()->uses_default_loader() && 192 (klass_name == ciSymbol::java_lang_Character_CharacterCache() || 193 klass_name == ciSymbol::java_lang_Byte_ByteCache() || 194 klass_name == ciSymbol::java_lang_Short_ShortCache() || 195 klass_name == ciSymbol::java_lang_Integer_IntegerCache() || 196 klass_name == ciSymbol::java_lang_Long_LongCache())); 197 } 198 199 // Debugging output 200 void print(); 201 void print_name_on(outputStream* st); 202 }; 203 204 #endif // SHARE_CI_CIFIELD_HPP 205