1 /* 2 * Copyright 1999-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 20 * CA 95054 USA or visit www.sun.com if you need additional information or 21 * have any questions. 22 * 23 */ 24 25 // ciField 26 // 27 // This class represents the result of a field lookup in the VM. 28 // The lookup may not succeed, in which case the information in 29 // the ciField will be incomplete. 30 class ciField : public ResourceObj { 31 CI_PACKAGE_ACCESS 32 friend class ciEnv; 33 friend class ciInstanceKlass; 34 friend class NonStaticFieldFiller; 35 36 private: 37 ciFlags _flags; 38 ciInstanceKlass* _holder; 39 ciSymbol* _name; 40 ciSymbol* _signature; 41 ciType* _type; 42 int _offset; 43 bool _is_constant; 44 ciInstanceKlass* _known_to_link_with; 45 ciConstant _constant_value; 46 47 // Used for will_link 48 int _cp_index; 49 50 ciType* compute_type(); 51 ciType* compute_type_impl(); 52 53 ciField(ciInstanceKlass* klass, int index); 54 ciField(fieldDescriptor* fd); 55 56 // shared constructor code 57 void initialize_from(fieldDescriptor* fd); 58 59 // The implementation of the print method. 60 void print_impl(outputStream* st); 61 62 public: 63 ciFlags flags() { return _flags; } 64 65 // Of which klass is this field a member? 66 // 67 // Usage note: the declared holder of a field is the class 68 // referenced by name in the bytecodes. The canonical holder 69 // is the most general class which holds the field. This 70 // method returns the canonical holder. The declared holder 71 // can be accessed via a method in ciBytecodeStream. 72 // 73 // Ex. 74 // class A { 75 // public int f = 7; 76 // } 77 // class B extends A { 78 // public void test() { 79 // System.out.println(f); 80 // } 81 // } 82 // 83 // A java compiler is permitted to compile the access to 84 // field f as: 85 // 86 // getfield B.f 87 // 88 // In that case the declared holder of f would be B and 89 // the canonical holder of f would be A. 90 ciInstanceKlass* holder() { return _holder; } 91 92 // Name of this field? 93 ciSymbol* name() { return _name; } 94 95 // Signature of this field? 96 ciSymbol* signature() { return _signature; } 97 98 // Of what type is this field? 99 ciType* type() { return (_type == NULL) ? compute_type() : _type; } 100 101 // How is this field actually stored in memory? 102 BasicType layout_type() { return type2field[(_type == NULL) ? T_OBJECT : _type->basic_type()]; } 103 104 // How big is this field in memory? 105 int size_in_bytes() { return type2aelembytes(layout_type()); } 106 107 // What is the offset of this field? 108 int offset() { 109 assert(_offset >= 1, "illegal call to offset()"); 110 return _offset; 111 } 112 113 // Same question, explicit units. (Fields are aligned to the byte level.) 114 int offset_in_bytes() { 115 return offset(); 116 } 117 118 // Is this field shared? 119 bool is_shared() { 120 // non-static fields of shared holders are cached 121 return _holder->is_shared() && !is_static(); 122 } 123 124 // Is this field a constant? 125 // 126 // Clarification: A field is considered constant if: 127 // 1. The field is both static and final 128 // 2. The canonical holder of the field has undergone 129 // static initialization. 130 // 3. If the field is an object or array, then the oop 131 // in question is allocated in perm space. 132 // 4. The field is not one of the special static/final 133 // non-constant fields. These are java.lang.System.in 134 // and java.lang.System.out. Abomination. 135 // 136 // Note: the check for case 4 is not yet implemented. 137 bool is_constant() { return _is_constant; } 138 139 // Get the constant value of this field. 140 ciConstant constant_value() { 141 assert(is_static() && is_constant(), "illegal call to constant_value()"); 142 return _constant_value; 143 } 144 145 // Get the constant value of non-static final field in the given 146 // object. 147 ciConstant constant_value_of(ciObject* object) { 148 assert(!is_static() && is_constant(), "only if field is non-static constant"); 149 assert(object->is_instance(), "must be instance"); 150 return object->as_instance()->field_value(this); 151 } 152 153 // Check for link time errors. Accessing a field from a 154 // certain class via a certain bytecode may or may not be legal. 155 // This call checks to see if an exception may be raised by 156 // an access of this field. 157 // 158 // Usage note: if the same field is accessed multiple times 159 // in the same compilation, will_link will need to be checked 160 // at each point of access. 161 bool will_link(ciInstanceKlass* accessing_klass, 162 Bytecodes::Code bc); 163 164 // Java access flags 165 bool is_public () { return flags().is_public(); } 166 bool is_private () { return flags().is_private(); } 167 bool is_protected () { return flags().is_protected(); } 168 bool is_static () { return flags().is_static(); } 169 bool is_final () { return flags().is_final(); } 170 bool is_volatile () { return flags().is_volatile(); } 171 bool is_transient () { return flags().is_transient(); } 172 173 // Debugging output 174 void print(); 175 void print_name_on(outputStream* st); 176 };