1 #ifdef USE_PRAGMA_IDENT_HDR 2 #pragma ident "@(#)ciField.hpp 1.23 07/09/28 10:23:24 JVM" 3 #endif 4 /* 5 * Copyright 1999-2008 Sun Microsystems, Inc. All Rights Reserved. 6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 7 * 8 * This code is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License version 2 only, as 10 * published by the Free Software Foundation. 11 * 12 * This code is distributed in the hope that it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 * version 2 for more details (a copy is included in the LICENSE file that 16 * accompanied this code). 17 * 18 * You should have received a copy of the GNU General Public License version 19 * 2 along with this work; if not, write to the Free Software Foundation, 20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 21 * 22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 23 * CA 95054 USA or visit www.sun.com if you need additional information or 24 * have any questions. 25 * 26 */ 27 28 // ciField 29 // 30 // This class represents the result of a field lookup in the VM. 31 // The lookup may not succeed, in which case the information in 32 // the ciField will be incomplete. 33 class ciField : public ResourceObj { 34 CI_PACKAGE_ACCESS 35 friend class ciEnv; 36 friend class ciInstanceKlass; 37 friend class NonStaticFieldFiller; 38 39 private: 40 ciFlags _flags; 41 ciInstanceKlass* _holder; 42 ciSymbol* _name; 43 ciSymbol* _signature; 44 ciType* _type; 45 int _offset; 46 bool _is_constant; 47 ciInstanceKlass* _known_to_link_with; 48 ciConstant _constant_value; 49 50 // Used for will_link 51 int _cp_index; 52 53 ciType* compute_type(); 54 ciType* compute_type_impl(); 55 56 ciField(ciInstanceKlass* klass, int index); 57 ciField(fieldDescriptor* fd); 58 59 // shared constructor code 60 void initialize_from(fieldDescriptor* fd); 61 62 // The implementation of the print method. 63 void print_impl(outputStream* st); 64 65 public: 66 ciFlags flags() { 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. 93 ciInstanceKlass* holder() { return _holder; } 94 95 // Name of this field? 96 ciSymbol* name() { return _name; } 97 98 // Signature of this field? 99 ciSymbol* signature() { return _signature; } 100 101 // Of what type is this field? 102 ciType* type() { return (_type == NULL) ? compute_type() : _type; } 103 104 // How is this field actually stored in memory? 105 BasicType layout_type() { return type2field[(_type == NULL) ? T_OBJECT : _type->basic_type()]; } 106 107 // How big is this field in memory? 108 int size_in_bytes() { return type2aelembytes(layout_type()); } 109 110 // What is the offset of this field? 111 int offset() { 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.) 117 int offset_in_bytes() { 118 return offset(); 119 } 120 121 // Is this field 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 canonical holder of the field has undergone 132 // static initialization. 133 // 3. If the field is an object or array, then the oop 134 // in question is allocated in perm space. 135 // 4. The field is not one of the special static/final 136 // non-constant fields. These are java.lang.System.in 137 // and java.lang.System.out. Abomination. 138 // 139 // Note: the check for case 4 is not yet implemented. 140 bool is_constant() { return _is_constant; } 141 142 // Get the constant value of this field. 143 ciConstant constant_value() { 144 assert(is_constant(), "illegal call to constant_value()"); 145 return _constant_value; 146 } 147 148 // Check for link time errors. Accessing a field from a 149 // certain class via a certain bytecode may or may not be legal. 150 // This call checks to see if an exception may be raised by 151 // an access of this field. 152 // 153 // Usage note: if the same field is accessed multiple times 154 // in the same compilation, will_link will need to be checked 155 // at each point of access. 156 bool will_link(ciInstanceKlass* accessing_klass, 157 Bytecodes::Code bc); 158 159 // Java access flags 160 bool is_public () { return flags().is_public(); } 161 bool is_private () { return flags().is_private(); } 162 bool is_protected () { return flags().is_protected(); } 163 bool is_static () { return flags().is_static(); } 164 bool is_final () { return flags().is_final(); } 165 bool is_volatile () { return flags().is_volatile(); } 166 bool is_transient () { return flags().is_transient(); } 167 168 // Debugging output 169 void print(); 170 void print_name_on(outputStream* st); 171 };