1 /* 2 * Copyright (c) 2011, 2018, 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_OOPS_INSTANCEMIRRORKLASS_HPP 26 #define SHARE_VM_OOPS_INSTANCEMIRRORKLASS_HPP 27 28 #include "classfile/systemDictionary.hpp" 29 #include "oops/instanceKlass.hpp" 30 #include "runtime/handles.hpp" 31 #include "utilities/macros.hpp" 32 33 class ClassFileParser; 34 35 // An InstanceMirrorKlass is a specialized InstanceKlass for 36 // java.lang.Class instances. These instances are special because 37 // they contain the static fields of the class in addition to the 38 // normal fields of Class. This means they are variable sized 39 // instances and need special logic for computing their size and for 40 // iteration of their oops. 41 42 43 class InstanceMirrorKlass: public InstanceKlass { 44 friend class VMStructs; 45 friend class InstanceKlass; 46 47 public: 48 static const KlassID ID = InstanceMirrorKlassID; 49 50 private: 51 static int _offset_of_static_fields; 52 InstanceMirrorKlass(const ClassFileParser & parser)53 InstanceMirrorKlass(const ClassFileParser& parser) : InstanceKlass(parser, InstanceKlass::_misc_kind_mirror, ID) {} 54 55 public: InstanceMirrorKlass()56 InstanceMirrorKlass() { assert(DumpSharedSpaces || UseSharedSpaces, "only for CDS"); } 57 58 // Casting from Klass* cast(Klass * k)59 static InstanceMirrorKlass* cast(Klass* k) { 60 assert(InstanceKlass::cast(k)->is_mirror_instance_klass(), 61 "cast to InstanceMirrorKlass"); 62 return static_cast<InstanceMirrorKlass*>(k); 63 } 64 65 // Returns the size of the instance including the extra static fields. 66 virtual int oop_size(oop obj) const; 67 68 // Static field offset is an offset into the Heap, should be converted by 69 // based on UseCompressedOop for traversal start_of_static_fields(oop obj)70 static HeapWord* start_of_static_fields(oop obj) { 71 return (HeapWord*)(cast_from_oop<intptr_t>(obj) + offset_of_static_fields()); 72 } 73 init_offset_of_static_fields()74 static void init_offset_of_static_fields() { 75 // Cache the offset of the static fields in the Class instance 76 assert(_offset_of_static_fields == 0, "once"); 77 _offset_of_static_fields = InstanceMirrorKlass::cast(SystemDictionary::Class_klass())->size_helper() << LogHeapWordSize; 78 } 79 offset_of_static_fields()80 static int offset_of_static_fields() { 81 return _offset_of_static_fields; 82 } 83 84 int compute_static_oop_field_count(oop obj); 85 86 // Given a Klass return the size of the instance 87 int instance_size(Klass* k); 88 89 // allocation 90 instanceOop allocate_instance(Klass* k, TRAPS); 91 92 static void serialize_offsets(class SerializeClosure* f) NOT_CDS_RETURN; 93 94 // Oop fields (and metadata) iterators 95 // 96 // The InstanceMirrorKlass iterators also visit the hidden Klass pointer. 97 98 // Iterate over the static fields. 99 template <typename T, class OopClosureType> 100 inline void oop_oop_iterate_statics(oop obj, OopClosureType* closure); 101 102 // Forward iteration 103 // Iterate over the oop fields and metadata. 104 template <typename T, class OopClosureType> 105 inline void oop_oop_iterate(oop obj, OopClosureType* closure); 106 107 // Reverse iteration 108 // Iterate over the oop fields and metadata. 109 template <typename T, class OopClosureType> 110 inline void oop_oop_iterate_reverse(oop obj, OopClosureType* closure); 111 112 // Bounded range iteration 113 // Iterate over the oop fields and metadata. 114 template <typename T, class OopClosureType> 115 inline void oop_oop_iterate_bounded(oop obj, OopClosureType* closure, MemRegion mr); 116 117 private: 118 119 // Iterate over the static fields. 120 template <typename T, class OopClosureType> 121 inline void oop_oop_iterate_statics_bounded(oop obj, OopClosureType* closure, MemRegion mr); 122 }; 123 124 #endif // SHARE_VM_OOPS_INSTANCEMIRRORKLASS_HPP 125