1 /* 2 * Copyright (c) 1999, 2013, 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_VM_CI_CIFIELD_HPP 26 #define SHARE_VM_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 33 // ciField 34 // 35 // This class represents the result of a field lookup in the VM. 36 // The lookup may not succeed, in which case the information in 37 // the ciField will be incomplete. 38 class ciField : public ResourceObj { 39 CI_PACKAGE_ACCESS 40 friend class ciEnv; 41 friend class ciInstanceKlass; 42 friend class NonStaticFieldFiller; 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 ciInstanceKlass* _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: 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. The field is not one of the special static/final 134 // non-constant fields. These are java.lang.System.in 135 // and java.lang.System.out. Abomination. 136 // 137 // A field is also considered constant if it is marked @Stable 138 // and is non-null (or non-zero, if a primitive). 139 // For non-static fields, the null/zero check must be 140 // arranged by the user, as constant_value().is_null_or_zero(). 141 bool is_constant() { return _is_constant; } 142 143 // Get the constant value of this field. 144 ciConstant constant_value() { 145 assert(is_static() && is_constant(), "illegal call to constant_value()"); 146 return _constant_value; 147 } 148 149 // Get the constant value of non-static final field in the given 150 // object. 151 ciConstant constant_value_of(ciObject* object) { 152 assert(!is_static() && is_constant(), "only if field is non-static constant"); 153 assert(object->is_instance(), "must be instance"); 154 return object->as_instance()->field_value(this); 155 } 156 157 // Check for link time errors. Accessing a field from a 158 // certain class 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(ciInstanceKlass* accessing_klass, 166 Bytecodes::Code bc); 167 168 // Java access flags 169 bool is_public () { return flags().is_public(); } 170 bool is_private () { return flags().is_private(); } 171 bool is_protected () { return flags().is_protected(); } 172 bool is_static () { return flags().is_static(); } 173 bool is_final () { return flags().is_final(); } 174 bool is_stable () { return flags().is_stable(); } 175 bool is_volatile () { return flags().is_volatile(); } 176 bool is_transient () { return flags().is_transient(); } 177 178 bool is_call_site_target() { 179 ciInstanceKlass* callsite_klass = CURRENT_ENV->CallSite_klass(); 180 if (callsite_klass == NULL) 181 return false; 182 return (holder()->is_subclass_of(callsite_klass) && (name() == ciSymbol::target_name())); 183 } 184 185 // Debugging output 186 void print(); 187 void print_name_on(outputStream* st); 188 }; 189 190 #endif // SHARE_VM_CI_CIFIELD_HPP