1 /*
2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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 *
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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23 */
24
25 #ifndef SHARE_MEMORY_UNIVERSE_HPP
26 #define SHARE_MEMORY_UNIVERSE_HPP
27
28 #include "gc/shared/verifyOption.hpp"
29 #include "memory/reservedSpace.hpp"
30 #include "oops/array.hpp"
31 #include "oops/oopHandle.hpp"
32 #include "runtime/handles.hpp"
33 #include "utilities/growableArray.hpp"
34
35 // Universe is a name space holding known system classes and objects in the VM.
36 //
37 // Loaded classes are accessible through the SystemDictionary.
38 //
39 // The object heap is allocated and accessed through Universe, and various allocation
40 // support is provided. Allocation by the interpreter and compiled code is done inline
41 // and bails out to Scavenge::invoke_and_allocate.
42
43 class CollectedHeap;
44 class DeferredObjAllocEvent;
45 class OopStorage;
46 class SerializeClosure;
47
48 class Universe: AllStatic {
49 // Ugh. Universe is much too friendly.
50 friend class SerialFullGC;
51 friend class oopDesc;
52 friend class ClassLoader;
53 friend class SystemDictionary;
54 friend class VMStructs;
55 friend class VM_PopulateDumpSharedSpace;
56 friend class Metaspace;
57 friend class AOTMetaspace;
58 friend class vmClasses;
59
60 friend jint universe_init();
61 friend void universe2_init();
62 friend bool universe_post_init();
63 friend void universe_post_module_init();
64
65 private:
66 // Known classes in the VM
67 static TypeArrayKlass* _typeArrayKlasses[T_LONG+1];
68 static ObjArrayKlass* _objectArrayKlass;
69 // Special int-Array that represents filler objects that are used by GC to overwrite
70 // dead objects. References to them are generally an error.
71 static Klass* _fillerArrayKlass;
72
73 // Known objects in the VM
74 static OopHandle _main_thread_group; // Reference to the main thread group object
75 static OopHandle _system_thread_group; // Reference to the system thread group object
76
77 static OopHandle _the_empty_class_array; // Canonicalized obj array of type java.lang.Class
78 static OopHandle _the_null_string; // A cache of "null" as a Java string
79 static OopHandle _the_min_jint_string; // A cache of "-2147483648" as a Java string
80
81 static OopHandle _the_null_sentinel; // A unique object pointer unused except as a sentinel for null.
82
83 // preallocated error objects (no backtrace)
84 static OopHandle _out_of_memory_errors;
85 static OopHandle _class_init_stack_overflow_error;
86
87 // preallocated cause message for delayed StackOverflowError
88 static OopHandle _delayed_stack_overflow_error_message;
89
90 static Array<int>* _the_empty_int_array; // Canonicalized int array
91 static Array<u2>* _the_empty_short_array; // Canonicalized short array
92 static Array<Klass*>* _the_empty_klass_array; // Canonicalized klass array
93 static Array<InstanceKlass*>* _the_empty_instance_klass_array; // Canonicalized instance klass array
94 static Array<Method*>* _the_empty_method_array; // Canonicalized method array
95
96 static Array<Klass*>* _the_array_interfaces_array;
97
98 static uintx _the_array_interfaces_bitmap;
99 static uintx _the_empty_klass_bitmap;
100
101 // array of preallocated error objects with backtrace
102 static OopHandle _preallocated_out_of_memory_error_array;
103
104 // number of preallocated error objects available for use
105 static volatile jint _preallocated_out_of_memory_error_avail_count;
106
107 // preallocated message detail strings for error objects
108 static OopHandle _msg_metaspace;
109 static OopHandle _msg_class_metaspace;
110
111 // References waiting to be transferred to the ReferenceHandler
112 static OopHandle _reference_pending_list;
113
114 // The particular choice of collected heap.
115 static CollectedHeap* _collectedHeap;
116
117 static intptr_t _non_oop_bits;
118
119
120 // array of dummy objects used with +FullGCAlot
121 DEBUG_ONLY(static OopHandle _fullgc_alot_dummy_array;)
122 DEBUG_ONLY(static int _fullgc_alot_dummy_next;)
123
124 // Compiler/dispatch support
125 static int _base_vtable_size; // Java vtbl size of klass Object (in words)
126
127 // Initialization
128 static bool _bootstrapping; // true during genesis
129 static bool _module_initialized; // true after call_initPhase2 called
130 static bool _fully_initialized; // true after universe_init and initialize_vtables called
131
132 // Shutdown
133 static volatile bool _is_shutting_down;
134
135 // the array of preallocated errors with backtraces
136 static objArrayOop preallocated_out_of_memory_errors();
137
138 static objArrayOop out_of_memory_errors();
139 // generate an out of memory error; if possible using an error with preallocated backtrace;
140 // otherwise return the given default error.
141 static oop gen_out_of_memory_error(oop default_err);
142
143 static OopStorage* _vm_weak;
144 static OopStorage* _vm_global;
145
146 static jint initialize_heap();
147 static void initialize_tlab();
148 static void initialize_basic_type_mirrors(TRAPS);
149 static void fixup_mirrors(TRAPS);
150
151 static void compute_base_vtable_size(); // compute vtable size of class Object
152
153 static void genesis(TRAPS); // Create the initial world
154
155 // Mirrors for primitive classes (created eagerly)
156 static oop check_mirror(oop m) {
157 assert(m != nullptr, "mirror not initialized");
158 return m;
159 }
160
161 // Debugging
162 static int _verify_count; // number of verifies done
163 static long verify_flags;
164
165 static uintptr_t _verify_oop_mask;
166 static uintptr_t _verify_oop_bits;
167
168 // Table of primitive type mirrors, excluding T_OBJECT and T_ARRAY
169 // but including T_VOID, hence the index including T_VOID
170 static OopHandle _basic_type_mirrors[T_VOID+1];
171
172 #if INCLUDE_CDS_JAVA_HEAP
173 // Each slot i stores an index that can be used to restore _basic_type_mirrors[i]
174 // from the archive heap using HeapShared::get_root(int)
175 static int _archived_basic_type_mirror_indices[T_VOID+1];
176 #endif
177
178 public:
179 static void calculate_verify_data(HeapWord* low_boundary, HeapWord* high_boundary) PRODUCT_RETURN;
180 static void set_verify_data(uintptr_t mask, uintptr_t bits) PRODUCT_RETURN;
181
182 // Known classes in the VM
183 static TypeArrayKlass* boolArrayKlass() { return typeArrayKlass(T_BOOLEAN); }
184 static TypeArrayKlass* byteArrayKlass() { return typeArrayKlass(T_BYTE); }
185 static TypeArrayKlass* charArrayKlass() { return typeArrayKlass(T_CHAR); }
186 static TypeArrayKlass* intArrayKlass() { return typeArrayKlass(T_INT); }
187 static TypeArrayKlass* shortArrayKlass() { return typeArrayKlass(T_SHORT); }
188 static TypeArrayKlass* longArrayKlass() { return typeArrayKlass(T_LONG); }
189 static TypeArrayKlass* floatArrayKlass() { return typeArrayKlass(T_FLOAT); }
190 static TypeArrayKlass* doubleArrayKlass() { return typeArrayKlass(T_DOUBLE); }
191
192 static ObjArrayKlass* objectArrayKlass() {
193 ObjArrayKlass* k = _objectArrayKlass;
194 assert(k != nullptr, "Object array klass should be initialized; too early?");
195 return k;
196 }
197
198 static Klass* fillerArrayKlass() {
199 Klass* k = _fillerArrayKlass;
200 assert(k != nullptr, "Filler array class should be initialized; too early?");
201 return k;
202 }
203
204 static TypeArrayKlass* typeArrayKlass(BasicType t) {
205 assert((uint)t >= T_BOOLEAN, "range check for type: %s", type2name(t));
206 assert((uint)t < T_LONG+1, "range check for type: %s", type2name(t));
207 TypeArrayKlass* k = _typeArrayKlasses[t];
208 assert(k != nullptr, "Type array class should be initialized; too early?");
209 return k;
210 }
211
212 // Known objects in the VM
213 static oop int_mirror();
214 static oop float_mirror();
215 static oop double_mirror();
216 static oop byte_mirror();
217 static oop bool_mirror();
218 static oop char_mirror();
219 static oop long_mirror();
220 static oop short_mirror();
221 static oop void_mirror();
222
223 static oop java_mirror(BasicType t);
224
225 static void load_archived_object_instances() NOT_CDS_JAVA_HEAP_RETURN;
226 #if INCLUDE_CDS_JAVA_HEAP
227 static void set_archived_basic_type_mirror_index(BasicType t, int index);
228 static void archive_exception_instances();
229 #endif
230
231 static oop main_thread_group();
232 static void set_main_thread_group(oop group);
233
234 static oop system_thread_group();
235 static void set_system_thread_group(oop group);
236
237 static objArrayOop the_empty_class_array ();
238
239 static oop the_null_string();
240 static oop the_min_jint_string();
241
242 static oop null_ptr_exception_instance();
243 static oop arithmetic_exception_instance();
244 static oop internal_error_instance();
245 static oop array_index_out_of_bounds_exception_instance();
246 static oop array_store_exception_instance();
247 static oop class_cast_exception_instance();
248 static oop preempted_exception_instance();
249 static oop vm_exception() { return internal_error_instance(); }
250
251 static Array<Klass*>* the_array_interfaces_array() { return _the_array_interfaces_array; }
252 static uintx the_array_interfaces_bitmap() { return _the_array_interfaces_bitmap; }
253
254 static Method* finalizer_register_method();
255 static Method* loader_addClass_method();
256 static Method* throw_illegal_access_error();
257 static Method* throw_no_such_method_error();
258 static Method* do_stack_walk_method();
259
260 static Method* is_substitutable_method();
261 static Method* value_object_hash_code_method();
262 static Method* is_substitutableAlt_method();
263
264 static oop the_null_sentinel();
265 static address the_null_sentinel_addr() { return (address) &_the_null_sentinel; }
266
267 // Function to initialize these
268 static void initialize_known_methods(JavaThread* current);
269
270 static void create_preallocated_out_of_memory_errors(TRAPS);
271
272 // Reference pending list manipulation. Access is protected by
273 // Heap_lock. The getter, setter and predicate require the caller
274 // owns the lock. Swap is used by parallel non-concurrent reference
275 // processing threads, where some higher level controller owns
276 // Heap_lock, so requires the lock is locked, but not necessarily by
277 // the current thread.
278 static oop reference_pending_list();
279 static void clear_reference_pending_list();
280 static bool has_reference_pending_list();
281 static oop swap_reference_pending_list(oop list);
282
283 static Array<int>* the_empty_int_array() { return _the_empty_int_array; }
284 static Array<u2>* the_empty_short_array() { return _the_empty_short_array; }
285 static Array<Method*>* the_empty_method_array() { return _the_empty_method_array; }
286 static Array<Klass*>* the_empty_klass_array() { return _the_empty_klass_array; }
287 static Array<InstanceKlass*>* the_empty_instance_klass_array() { return _the_empty_instance_klass_array; }
288
289 static uintx the_empty_klass_bitmap() { return _the_empty_klass_bitmap; }
290
291 // OutOfMemoryError support. Returns an error with the required message. The returned error
292 // may or may not have a backtrace. If error has a backtrace then the stack trace is already
293 // filled in.
294 static oop out_of_memory_error_java_heap();
295 static oop out_of_memory_error_java_heap_without_backtrace();
296 static oop out_of_memory_error_c_heap();
297 static oop out_of_memory_error_metaspace();
298 static oop out_of_memory_error_class_metaspace();
299 static oop out_of_memory_error_array_size();
300 static oop out_of_memory_error_gc_overhead_limit();
301 static oop out_of_memory_error_realloc_objects();
302
303 static oop delayed_stack_overflow_error_message();
304
305 // Saved StackOverflowError and OutOfMemoryError for use when
306 // class initialization can't create ExceptionInInitializerError.
307 static oop class_init_stack_overflow_error();
308 static oop class_init_out_of_memory_error();
309
310 // If it's a certain type of OOME object
311 static bool is_out_of_memory_error_metaspace(oop ex_obj);
312 static bool is_out_of_memory_error_class_metaspace(oop ex_obj);
313
314 // The particular choice of collected heap.
315 static CollectedHeap* heap() { return _collectedHeap; }
316
317 static void before_exit();
318
319 DEBUG_ONLY(static bool is_stw_gc_active();)
320 DEBUG_ONLY(static bool is_in_heap(const void* p);)
321 DEBUG_ONLY(static bool is_in_heap_or_null(const void* p) { return p == nullptr || is_in_heap(p); })
322
323 // Reserve Java heap and determine CompressedOops mode
324 static ReservedHeapSpace reserve_heap(size_t heap_size, size_t alignment, size_t desired_page_size = 0);
325
326 // Global OopStorages
327 static OopStorage* vm_weak();
328 static OopStorage* vm_global();
329 static void oopstorage_init();
330
331 // Testers
332 static bool is_bootstrapping() { return _bootstrapping; }
333 static bool is_module_initialized() { return _module_initialized; }
334 static bool is_fully_initialized() { return _fully_initialized; }
335
336 static bool is_shutting_down() { return AtomicAccess::load_acquire(&_is_shutting_down); }
337
338 static bool on_page_boundary(void* addr);
339 static bool should_fill_in_stack_trace(Handle throwable);
340 static void check_alignment(uintx size, uintx alignment, const char* name);
341
342 // CDS support
343 static void serialize(SerializeClosure* f);
344
345 // Apply the closure to all klasses for basic types (classes not present in
346 // SystemDictionary).
347 static void basic_type_classes_do(KlassClosure* closure);
348 static void metaspace_pointers_do(MetaspaceClosure* it);
349
350 // Debugging
351 enum VERIFY_FLAGS {
352 Verify_Threads = 1,
353 Verify_Heap = 2,
354 Verify_SymbolTable = 4,
355 Verify_StringTable = 8,
356 Verify_CodeCache = 16,
357 Verify_SystemDictionary = 32,
358 Verify_ClassLoaderDataGraph = 64,
359 Verify_MetaspaceUtils = 128,
360 Verify_JNIHandles = 256,
361 Verify_CodeCacheOops = 512,
362 Verify_ResolvedMethodTable = 1024,
363 Verify_StringDedup = 2048,
364 Verify_All = -1
365 };
366 static void initialize_verify_flags();
367 static bool should_verify_subset(uint subset);
368 static void verify(VerifyOption option, const char* prefix);
369 static void verify(const char* prefix) {
370 verify(VerifyOption::Default, prefix);
371 }
372 static void verify() {
373 verify("");
374 }
375
376 static int verify_count() { return _verify_count; }
377 static void print_on(outputStream* st);
378 static void print_heap_at_SIGBREAK();
379
380 // Change the number of dummy objects kept reachable by the full gc dummy
381 // array; this should trigger relocation in a sliding compaction collector.
382 DEBUG_ONLY(static bool release_fullgc_alot_dummy();)
383 // The non-oop pattern (see compiledIC.hpp, etc)
384 static void* non_oop_word();
385 static bool contains_non_oop_word(void* p);
386
387 // Oop verification (see MacroAssembler::verify_oop)
388 static uintptr_t verify_oop_mask() PRODUCT_RETURN0;
389 static uintptr_t verify_oop_bits() PRODUCT_RETURN0;
390 static uintptr_t verify_mark_bits() PRODUCT_RETURN0;
391 static uintptr_t verify_mark_mask() PRODUCT_RETURN0;
392
393 // Compiler support
394 static int base_vtable_size() { return _base_vtable_size; }
395 };
396
397 #endif // SHARE_MEMORY_UNIVERSE_HPP