1 /*
2 * Copyright (c) 2024, 2026, 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
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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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
24
25 #ifndef SHARE_CDS_AOTMAPPEDHEAPWRITER_HPP
26 #define SHARE_CDS_AOTMAPPEDHEAPWRITER_HPP
27
28 #include "cds/aotMapLogger.hpp"
29 #include "cds/heapShared.hpp"
30 #include "memory/allocation.hpp"
31 #include "memory/allStatic.hpp"
32 #include "oops/compressedOops.hpp"
33 #include "oops/oopHandle.hpp"
34 #include "utilities/bitMap.hpp"
35 #include "utilities/exceptions.hpp"
36 #include "utilities/growableArray.hpp"
37 #include "utilities/hashTable.hpp"
38 #include "utilities/macros.hpp"
39
40 class MemRegion;
41
42 #if INCLUDE_CDS_JAVA_HEAP
43 class AOTMappedHeapWriter : AllStatic {
44 friend class HeapShared;
45 friend class AOTMappedHeapLoader;
46 // AOTMappedHeapWriter manipulates three types of addresses:
47 //
48 // "source" vs "buffered" vs "requested"
49 //
50 // (Note: the design and convention is the same as for the archiving of Metaspace objects.
51 // See archiveBuilder.hpp.)
52 //
53 // - "source objects" are regular Java objects allocated during the execution
54 // of "java -Xshare:dump". They can be used as regular oops.
55 //
56 // Between HeapShared::start_scanning_for_oops() and HeapShared::end_scanning_for_oops(),
57 // we recursively search for the oops that need to be stored into the CDS archive.
58 // These are entered into HeapShared::archived_object_cache().
59 //
60 // - "buffered objects" are copies of the "source objects", and are stored in into
61 // AOTMappedHeapWriter::_buffer, which is a GrowableArray that sits outside of
62 // the valid heap range. Therefore we avoid using the addresses of these copies
63 // as oops. They are usually called "buffered_addr" in the code (of the type "address").
64 //
65 // The buffered objects are stored contiguously, possibly with interleaving fillers
66 // to make sure no objects span across boundaries of MIN_GC_REGION_ALIGNMENT.
67 //
68 // - Each archived object has a "requested address" -- at run time, if the object
69 // can be mapped at this address, we can avoid relocation.
70 //
71 // The requested address of an archived object is essentially its buffered_addr + delta,
72 // where delta is (_requested_bottom - buffer_bottom());
73 //
74 // The requested addresses of all archived objects are within [_requested_bottom, _requested_top).
75 // See AOTMappedHeapWriter::set_requested_address_range() for more info.
76 // ----------------------------------------------------------------------
77
78 public:
79 static const intptr_t NOCOOPS_REQUESTED_BASE = 0x10000000;
80
81 // The minimum region size of all collectors that are supported by CDS.
82 // G1 heap region size can never be smaller than 1M.
83 // Shenandoah heap region size can never be smaller than 256K.
84 static constexpr int MIN_GC_REGION_ALIGNMENT = 256 * K;
85
86 // The heap contents are required to be deterministic when dumping "old" CDS archives, in order
87 // to support reproducible lib/server/classes*.jsa when building the JDK.
88 static bool is_writing_deterministic_heap() { return _is_writing_deterministic_heap; }
89
90 // The oop encoding used by the archived heap objects.
91 static CompressedOops::Mode narrow_oop_mode();
92 static address narrow_oop_base();
93 static int narrow_oop_shift();
94
95 static const int INITIAL_TABLE_SIZE = 15889; // prime number
96 static const int MAX_TABLE_SIZE = 1000000;
97
98 private:
99 class EmbeddedOopRelocator;
100 struct NativePointerInfo {
101 oop _src_obj;
102 int _field_offset;
103 };
104
105 static bool _is_writing_deterministic_heap;
106 static GrowableArrayCHeap<u1, mtClassShared>* _buffer;
107
108 // The number of bytes that have written into _buffer (may be smaller than _buffer->length()).
109 static size_t _buffer_used;
110
111 // The heap root segments information.
112 static HeapRootSegments _heap_root_segments;
113
114 // The address range of the requested location of the archived heap objects.
115 static address _requested_bottom; // The requested address of the lowest archived heap object
116 static address _requested_top; // The exclusive end of the highest archived heap object
117
118 static GrowableArrayCHeap<NativePointerInfo, mtClassShared>* _native_pointers;
119 static GrowableArrayCHeap<oop, mtClassShared>* _source_objs;
120
121 // We sort _source_objs_order to minimize the number of bits in ptrmap and oopmap.
122 // See comments near the body of AOTMappedHeapWriter::compare_objs_by_oop_fields().
123 // The objects will be written in the order of:
124 //_source_objs->at(_source_objs_order->at(0)._index)
125 // source_objs->at(_source_objs_order->at(1)._index)
126 // source_objs->at(_source_objs_order->at(2)._index)
127 // ...
128 struct HeapObjOrder {
129 int _index; // The location of this object in _source_objs
130 int _rank; // A lower rank means the object will be written at a lower location.
131 };
132 static GrowableArrayCHeap<HeapObjOrder, mtClassShared>* _source_objs_order;
133
134 typedef ResizeableHashTable<size_t, OopHandle,
135 AnyObj::C_HEAP,
136 mtClassShared> BufferOffsetToSourceObjectTable;
137 static BufferOffsetToSourceObjectTable* _buffer_offset_to_source_obj_table;
138
139 static void allocate_buffer();
140 static void ensure_buffer_space(size_t min_bytes);
141
142 // Both Java bytearray and GrowableArraty use int indices and lengths. Do a safe typecast with range check
143 static int to_array_index(size_t i) {
144 assert(i <= (size_t)max_jint, "must be");
145 return (int)i;
146 }
147 static int to_array_length(size_t n) {
148 return to_array_index(n);
149 }
150
151 template <typename T> static T offset_to_buffered_address(size_t offset) {
152 return (T)(_buffer->adr_at(to_array_index(offset)));
153 }
154
155 static address buffer_bottom() {
156 return offset_to_buffered_address<address>(0);
157 }
158
159 // The exclusive end of the last object that was copied into the buffer.
160 static address buffer_top() {
161 return buffer_bottom() + _buffer_used;
162 }
163
164 static bool in_buffer(address buffered_addr) {
165 return (buffer_bottom() <= buffered_addr) && (buffered_addr < buffer_top());
166 }
167
168 static size_t buffered_address_to_offset(address buffered_addr) {
169 assert(in_buffer(buffered_addr), "sanity");
170 return buffered_addr - buffer_bottom();
171 }
172
173 static void root_segment_at_put(objArrayOop segment, int index, oop root);
174 static objArrayOop allocate_root_segment(size_t offset, int element_count);
175 static void copy_roots_to_buffer(GrowableArrayCHeap<oop, mtClassShared>* roots);
176 static void copy_source_objs_to_buffer(GrowableArrayCHeap<oop, mtClassShared>* roots);
177 static size_t copy_one_source_obj_to_buffer(oop src_obj);
178 static void update_stats(oop src_obj);
179
180 static void maybe_fill_gc_region_gap(size_t required_byte_size);
181 static size_t filler_array_byte_size(int length);
182 static int filler_array_length(size_t fill_bytes);
183 static HeapWord* init_filler_array_at_buffer_top(int array_length, size_t fill_bytes);
184
185 static void set_requested_address_range(ArchiveMappedHeapInfo* info);
186 static void mark_native_pointers(oop orig_obj);
187 static void relocate_embedded_oops(GrowableArrayCHeap<oop, mtClassShared>* roots, ArchiveMappedHeapInfo* info);
188 static void compute_ptrmap(ArchiveMappedHeapInfo *info);
189 static bool is_in_requested_range(oop o);
190 static oop requested_obj_from_buffer_offset(size_t offset);
191
192 static oop load_oop_from_buffer(oop* buffered_addr);
193 static oop load_oop_from_buffer(narrowOop* buffered_addr);
194 inline static void store_oop_in_buffer(oop* buffered_addr, oop requested_obj);
195 inline static void store_oop_in_buffer(narrowOop* buffered_addr, oop requested_obj);
196
197 template <typename T> static oop load_source_oop_from_buffer(T* buffered_addr);
198 template <typename T> static void store_requested_oop_in_buffer(T* buffered_addr, oop request_oop);
199
200 template <typename T> static T* requested_addr_to_buffered_addr(T* p);
201 template <typename T> static void relocate_field_in_buffer(T* field_addr_in_buffer, oop source_referent, CHeapBitMap* oopmap);
202 template <typename T> static void mark_oop_pointer(T* buffered_addr, CHeapBitMap* oopmap);
203
204 static void update_header_for_requested_obj(oop requested_obj, oop src_obj, Klass* src_klass);
205
206 static int compare_objs_by_oop_fields(HeapObjOrder* a, HeapObjOrder* b);
207 static void sort_source_objs();
208
209 public:
210 static void init() NOT_CDS_JAVA_HEAP_RETURN;
211 static void delete_tables_with_raw_oops();
212 static void add_source_obj(oop src_obj);
213 static bool is_too_large_to_archive(size_t size);
214 static bool is_too_large_to_archive(oop obj);
215 static bool is_string_too_large_to_archive(oop string);
216 static void write(GrowableArrayCHeap<oop, mtClassShared>*, ArchiveMappedHeapInfo* heap_info);
217 static address requested_address(); // requested address of the lowest achived heap object
218 static size_t get_filler_size_at(address buffered_addr);
219
220 static void mark_native_pointer(oop src_obj, int offset);
221 static oop source_obj_to_requested_obj(oop src_obj);
222 static oop buffered_addr_to_source_obj(address buffered_addr);
223 static address buffered_addr_to_requested_addr(address buffered_addr);
224 static Klass* real_klass_of_buffered_oop(address buffered_addr);
225 static size_t size_of_buffered_oop(address buffered_addr);
226
227 static AOTMapLogger::OopDataIterator* oop_iterator(ArchiveMappedHeapInfo* heap_info);
228 };
229 #endif // INCLUDE_CDS_JAVA_HEAP
230 #endif // SHARE_CDS_AOTMAPPEDHEAPWRITER_HPP