1 /*
  2  * Copyright (c) 2024, 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 #include "precompiled.hpp"
 26 #include "cds/archiveHeapWriter.hpp"
 27 #include "cds/cdsConfig.hpp"
 28 #include "cds/filemap.hpp"
 29 #include "cds/heapShared.hpp"
 30 #include "classfile/systemDictionary.hpp"
 31 #include "gc/shared/collectedHeap.hpp"
 32 #include "memory/iterator.inline.hpp"
 33 #include "memory/oopFactory.hpp"
 34 #include "memory/universe.hpp"
 35 #include "oops/compressedOops.hpp"
 36 #include "oops/oop.inline.hpp"
 37 #include "oops/objArrayOop.inline.hpp"
 38 #include "oops/oopHandle.inline.hpp"
 39 #include "oops/typeArrayKlass.hpp"
 40 #include "oops/typeArrayOop.hpp"
 41 #include "runtime/java.hpp"
 42 #include "runtime/mutexLocker.hpp"
 43 #include "utilities/bitMap.inline.hpp"
 44 #if INCLUDE_G1GC
 45 #include "gc/g1/g1CollectedHeap.hpp"
 46 #include "gc/g1/g1HeapRegion.hpp"
 47 #endif
 48 
 49 #if INCLUDE_CDS_JAVA_HEAP
 50 
 51 GrowableArrayCHeap<u1, mtClassShared>* ArchiveHeapWriter::_buffer = nullptr;
 52 
 53 // The following are offsets from buffer_bottom()
 54 size_t ArchiveHeapWriter::_buffer_used;
 55 size_t ArchiveHeapWriter::_heap_roots_offset;
 56 
 57 size_t ArchiveHeapWriter::_heap_roots_word_size;
 58 
 59 address ArchiveHeapWriter::_requested_bottom;
 60 address ArchiveHeapWriter::_requested_top;
 61 
 62 GrowableArrayCHeap<ArchiveHeapWriter::NativePointerInfo, mtClassShared>* ArchiveHeapWriter::_native_pointers;
 63 GrowableArrayCHeap<oop, mtClassShared>* ArchiveHeapWriter::_source_objs;
 64 GrowableArrayCHeap<ArchiveHeapWriter::HeapObjOrder, mtClassShared>* ArchiveHeapWriter::_source_objs_order;
 65 
 66 ArchiveHeapWriter::BufferOffsetToSourceObjectTable*
 67   ArchiveHeapWriter::_buffer_offset_to_source_obj_table = nullptr;
 68 
 69 
 70 typedef ResourceHashtable<address, size_t,
 71       127, // prime number
 72       AnyObj::C_HEAP,
 73       mtClassShared> FillersTable;
 74 static FillersTable* _fillers;
 75 static int _num_native_ptrs = 0;
 76 
 77 void ArchiveHeapWriter::init() {
 78   if (HeapShared::can_write()) {
 79     Universe::heap()->collect(GCCause::_java_lang_system_gc);
 80 
 81     _buffer_offset_to_source_obj_table = new BufferOffsetToSourceObjectTable(/*size (prime)*/36137, /*max size*/1 * M);
 82     _fillers = new FillersTable();
 83     _requested_bottom = nullptr;
 84     _requested_top = nullptr;
 85 
 86     _native_pointers = new GrowableArrayCHeap<NativePointerInfo, mtClassShared>(2048);
 87     _source_objs = new GrowableArrayCHeap<oop, mtClassShared>(10000);
 88 
 89     guarantee(UseG1GC, "implementation limitation");
 90     guarantee(MIN_GC_REGION_ALIGNMENT <= /*G1*/HeapRegion::min_region_size_in_words() * HeapWordSize, "must be");
 91   }
 92 }
 93 
 94 void ArchiveHeapWriter::add_source_obj(oop src_obj) {
 95   _source_objs->append(src_obj);
 96 }
 97 
 98 void ArchiveHeapWriter::write(GrowableArrayCHeap<oop, mtClassShared>* roots,
 99                               ArchiveHeapInfo* heap_info) {
100   assert(HeapShared::can_write(), "sanity");
101   allocate_buffer();
102   copy_source_objs_to_buffer(roots);
103   set_requested_address(heap_info);
104   relocate_embedded_oops(roots, heap_info);
105 }
106 
107 bool ArchiveHeapWriter::is_too_large_to_archive(oop o) {
108   return is_too_large_to_archive(o->size());
109 }
110 
111 bool ArchiveHeapWriter::is_string_too_large_to_archive(oop string) {
112   typeArrayOop value = java_lang_String::value_no_keepalive(string);
113   return is_too_large_to_archive(value);
114 }
115 
116 bool ArchiveHeapWriter::is_too_large_to_archive(size_t size) {
117   assert(size > 0, "no zero-size object");
118   assert(size * HeapWordSize > size, "no overflow");
119   static_assert(MIN_GC_REGION_ALIGNMENT > 0, "must be positive");
120 
121   size_t byte_size = size * HeapWordSize;
122   if (byte_size > size_t(MIN_GC_REGION_ALIGNMENT)) {
123     return true;
124   } else {
125     return false;
126   }
127 }
128 
129 // Various lookup functions between source_obj, buffered_obj and requested_obj
130 bool ArchiveHeapWriter::is_in_requested_range(oop o) {
131   assert(_requested_bottom != nullptr, "do not call before _requested_bottom is initialized");
132   address a = cast_from_oop<address>(o);
133   return (_requested_bottom <= a && a < _requested_top);
134 }
135 
136 oop ArchiveHeapWriter::requested_obj_from_buffer_offset(size_t offset) {
137   oop req_obj = cast_to_oop(_requested_bottom + offset);
138   assert(is_in_requested_range(req_obj), "must be");
139   return req_obj;
140 }
141 
142 oop ArchiveHeapWriter::source_obj_to_requested_obj(oop src_obj) {
143   assert(CDSConfig::is_dumping_heap(), "dump-time only");
144   HeapShared::CachedOopInfo* p = HeapShared::archived_object_cache()->get(src_obj);
145   if (p != nullptr) {
146     return requested_obj_from_buffer_offset(p->buffer_offset());
147   } else {
148     return nullptr;
149   }
150 }
151 
152 oop ArchiveHeapWriter::buffered_addr_to_source_obj(address buffered_addr) {
153   oop* p = _buffer_offset_to_source_obj_table->get(buffered_address_to_offset(buffered_addr));
154   if (p != nullptr) {
155     return *p;
156   } else {
157     return nullptr;
158   }
159 }
160 
161 address ArchiveHeapWriter::buffered_addr_to_requested_addr(address buffered_addr) {
162   return _requested_bottom + buffered_address_to_offset(buffered_addr);
163 }
164 
165 oop ArchiveHeapWriter::heap_roots_requested_address() {
166   return cast_to_oop(_requested_bottom + _heap_roots_offset);
167 }
168 
169 address ArchiveHeapWriter::requested_address() {
170   assert(_buffer != nullptr, "must be initialized");
171   return _requested_bottom;
172 }
173 
174 void ArchiveHeapWriter::allocate_buffer() {
175   int initial_buffer_size = 100000;
176   _buffer = new GrowableArrayCHeap<u1, mtClassShared>(initial_buffer_size);
177   _buffer_used = 0;
178   ensure_buffer_space(1); // so that buffer_bottom() works
179 }
180 
181 void ArchiveHeapWriter::ensure_buffer_space(size_t min_bytes) {
182   // We usually have very small heaps. If we get a huge one it's probably caused by a bug.
183   guarantee(min_bytes <= max_jint, "we dont support archiving more than 2G of objects");
184   _buffer->at_grow(to_array_index(min_bytes));
185 }
186 
187 void ArchiveHeapWriter::copy_roots_to_buffer(GrowableArrayCHeap<oop, mtClassShared>* roots) {
188   Klass* k = Universe::objectArrayKlass(); // already relocated to point to archived klass
189   int length = roots->length();
190   _heap_roots_word_size = objArrayOopDesc::object_size(length);
191   size_t byte_size = _heap_roots_word_size * HeapWordSize;
192   if (byte_size >= MIN_GC_REGION_ALIGNMENT) {
193     log_error(cds, heap)("roots array is too large. Please reduce the number of classes");
194     vm_exit(1);
195   }
196 
197   maybe_fill_gc_region_gap(byte_size);
198 
199   size_t new_used = _buffer_used + byte_size;
200   ensure_buffer_space(new_used);
201 
202   HeapWord* mem = offset_to_buffered_address<HeapWord*>(_buffer_used);
203   memset(mem, 0, byte_size);
204   {
205     // This is copied from MemAllocator::finish
206     oopDesc::set_mark(mem, markWord::prototype());
207     oopDesc::release_set_klass(mem, k);
208   }
209   {
210     // This is copied from ObjArrayAllocator::initialize
211     arrayOopDesc::set_length(mem, length);
212   }
213 
214   objArrayOop arrayOop = objArrayOop(cast_to_oop(mem));
215   for (int i = 0; i < length; i++) {
216     // Do not use arrayOop->obj_at_put(i, o) as arrayOop is outside of the real heap!
217     oop o = roots->at(i);
218     if (UseCompressedOops) {
219       * arrayOop->obj_at_addr<narrowOop>(i) = CompressedOops::encode(o);
220     } else {
221       * arrayOop->obj_at_addr<oop>(i) = o;
222     }
223   }
224   log_info(cds, heap)("archived obj roots[%d] = " SIZE_FORMAT " bytes, klass = %p, obj = %p", length, byte_size, k, mem);
225 
226   _heap_roots_offset = _buffer_used;
227   _buffer_used = new_used;
228 }
229 
230 static int oop_sorting_rank(oop o) {
231   bool has_oop_ptr, has_native_ptr;
232   HeapShared::get_pointer_info(o, has_oop_ptr, has_native_ptr);
233 
234   if (!has_oop_ptr) {
235     if (!has_native_ptr) {
236       return 0;
237     } else {
238       return 1;
239     }
240   } else {
241     if (has_native_ptr) {
242       return 2;
243     } else {
244       return 3;
245     }
246   }
247 }
248 
249 // The goal is to sort the objects in increasing order of:
250 // - objects that have no pointers
251 // - objects that have only native pointers
252 // - objects that have both native and oop pointers
253 // - objects that have only oop pointers
254 int ArchiveHeapWriter::compare_objs_by_oop_fields(HeapObjOrder* a, HeapObjOrder* b) {
255   int rank_a = a->_rank;
256   int rank_b = b->_rank;
257 
258   if (rank_a != rank_b) {
259     return rank_a - rank_b;
260   } else {
261     // If they are the same rank, sort them by their position in the _source_objs array
262     return a->_index - b->_index;
263   }
264 }
265 
266 void ArchiveHeapWriter::sort_source_objs() {
267   log_info(cds)("sorting heap objects");
268   int len = _source_objs->length();
269   _source_objs_order = new GrowableArrayCHeap<HeapObjOrder, mtClassShared>(len);
270 
271   for (int i = 0; i < len; i++) {
272     oop o = _source_objs->at(i);
273     int rank = oop_sorting_rank(o);
274     HeapObjOrder os = {i, rank};
275     _source_objs_order->append(os);
276   }
277   log_info(cds)("computed ranks");
278   _source_objs_order->sort(compare_objs_by_oop_fields);
279   log_info(cds)("sorting heap objects done");
280 }
281 
282 void ArchiveHeapWriter::copy_source_objs_to_buffer(GrowableArrayCHeap<oop, mtClassShared>* roots) {
283   sort_source_objs();
284   for (int i = 0; i < _source_objs_order->length(); i++) {
285     int src_obj_index = _source_objs_order->at(i)._index;
286     oop src_obj = _source_objs->at(src_obj_index);
287     HeapShared::CachedOopInfo* info = HeapShared::archived_object_cache()->get(src_obj);
288     assert(info != nullptr, "must be");
289     size_t buffer_offset = copy_one_source_obj_to_buffer(src_obj);
290     info->set_buffer_offset(buffer_offset);
291 
292     _buffer_offset_to_source_obj_table->put_when_absent(buffer_offset, src_obj);
293     _buffer_offset_to_source_obj_table->maybe_grow();
294   }
295 
296   copy_roots_to_buffer(roots);
297 
298   log_info(cds)("Size of heap region = " SIZE_FORMAT " bytes, %d objects, %d roots, %d native ptrs",
299                 _buffer_used, _source_objs->length() + 1, roots->length(), _num_native_ptrs);
300 }
301 
302 size_t ArchiveHeapWriter::filler_array_byte_size(int length) {
303   size_t byte_size = objArrayOopDesc::object_size(length) * HeapWordSize;
304   return byte_size;
305 }
306 
307 int ArchiveHeapWriter::filler_array_length(size_t fill_bytes) {
308   assert(is_object_aligned(fill_bytes), "must be");
309   size_t elemSize = (UseCompressedOops ? sizeof(narrowOop) : sizeof(oop));
310 
311   int initial_length = to_array_length(fill_bytes / elemSize);
312   for (int length = initial_length; length >= 0; length --) {
313     size_t array_byte_size = filler_array_byte_size(length);
314     if (array_byte_size == fill_bytes) {
315       return length;
316     }
317   }
318 
319   ShouldNotReachHere();
320   return -1;
321 }
322 
323 HeapWord* ArchiveHeapWriter::init_filler_array_at_buffer_top(int array_length, size_t fill_bytes) {
324   assert(UseCompressedClassPointers, "Archived heap only supported for compressed klasses");
325   Klass* oak = Universe::objectArrayKlass(); // already relocated to point to archived klass
326   HeapWord* mem = offset_to_buffered_address<HeapWord*>(_buffer_used);
327   memset(mem, 0, fill_bytes);
328   oopDesc::set_mark(mem, markWord::prototype());
329   narrowKlass nk = ArchiveBuilder::current()->get_requested_narrow_klass(oak);
330   cast_to_oop(mem)->set_narrow_klass(nk);
331   arrayOopDesc::set_length(mem, array_length);
332   return mem;
333 }
334 
335 void ArchiveHeapWriter::maybe_fill_gc_region_gap(size_t required_byte_size) {
336   // We fill only with arrays (so we don't need to use a single HeapWord filler if the
337   // leftover space is smaller than a zero-sized array object). Therefore, we need to
338   // make sure there's enough space of min_filler_byte_size in the current region after
339   // required_byte_size has been allocated. If not, fill the remainder of the current
340   // region.
341   size_t min_filler_byte_size = filler_array_byte_size(0);
342   size_t new_used = _buffer_used + required_byte_size + min_filler_byte_size;
343 
344   const size_t cur_min_region_bottom = align_down(_buffer_used, MIN_GC_REGION_ALIGNMENT);
345   const size_t next_min_region_bottom = align_down(new_used, MIN_GC_REGION_ALIGNMENT);
346 
347   if (cur_min_region_bottom != next_min_region_bottom) {
348     // Make sure that no objects span across MIN_GC_REGION_ALIGNMENT. This way
349     // we can map the region in any region-based collector.
350     assert(next_min_region_bottom > cur_min_region_bottom, "must be");
351     assert(next_min_region_bottom - cur_min_region_bottom == MIN_GC_REGION_ALIGNMENT,
352            "no buffered object can be larger than %d bytes",  MIN_GC_REGION_ALIGNMENT);
353 
354     const size_t filler_end = next_min_region_bottom;
355     const size_t fill_bytes = filler_end - _buffer_used;
356     assert(fill_bytes > 0, "must be");
357     ensure_buffer_space(filler_end);
358 
359     int array_length = filler_array_length(fill_bytes);
360     log_info(cds, heap)("Inserting filler obj array of %d elements (" SIZE_FORMAT " bytes total) @ buffer offset " SIZE_FORMAT,
361                         array_length, fill_bytes, _buffer_used);
362     HeapWord* filler = init_filler_array_at_buffer_top(array_length, fill_bytes);
363     _buffer_used = filler_end;
364     _fillers->put((address)filler, fill_bytes);
365   }
366 }
367 
368 size_t ArchiveHeapWriter::get_filler_size_at(address buffered_addr) {
369   size_t* p = _fillers->get(buffered_addr);
370   if (p != nullptr) {
371     assert(*p > 0, "filler must be larger than zero bytes");
372     return *p;
373   } else {
374     return 0; // buffered_addr is not a filler
375   }
376 }
377 
378 template <typename T>
379 void update_buffered_object_field(address buffered_obj, int field_offset, T value) {
380   T* field_addr = cast_to_oop(buffered_obj)->field_addr<T>(field_offset);
381   *field_addr = value;
382 }
383 
384 size_t ArchiveHeapWriter::copy_one_source_obj_to_buffer(oop src_obj) {
385   assert(!is_too_large_to_archive(src_obj), "already checked");
386   size_t byte_size = src_obj->size() * HeapWordSize;
387   assert(byte_size > 0, "no zero-size objects");
388 
389   // For region-based collectors such as G1, the archive heap may be mapped into
390   // multiple regions. We need to make sure that we don't have an object that can possible
391   // span across two regions.
392   maybe_fill_gc_region_gap(byte_size);
393 
394   size_t new_used = _buffer_used + byte_size;
395   assert(new_used > _buffer_used, "no wrap around");
396 
397   size_t cur_min_region_bottom = align_down(_buffer_used, MIN_GC_REGION_ALIGNMENT);
398   size_t next_min_region_bottom = align_down(new_used, MIN_GC_REGION_ALIGNMENT);
399   assert(cur_min_region_bottom == next_min_region_bottom, "no object should cross minimal GC region boundaries");
400 
401   ensure_buffer_space(new_used);
402 
403   address from = cast_from_oop<address>(src_obj);
404   address to = offset_to_buffered_address<address>(_buffer_used);
405   assert(is_object_aligned(_buffer_used), "sanity");
406   assert(is_object_aligned(byte_size), "sanity");
407   memcpy(to, from, byte_size);
408 
409   // These native pointers will be restored explicitly at run time.
410   if (java_lang_Module::is_instance(src_obj)) {
411     update_buffered_object_field<ModuleEntry*>(to, java_lang_Module::module_entry_offset(), nullptr);
412   } else if (java_lang_ClassLoader::is_instance(src_obj)) {
413 #ifdef ASSERT
414     // We only archive these loaders
415     if (src_obj != SystemDictionary::java_platform_loader() &&
416         src_obj != SystemDictionary::java_system_loader()) {
417       assert(src_obj->klass()->name()->equals("jdk/internal/loader/ClassLoaders$BootClassLoader"), "must be");
418     }
419 #endif
420     update_buffered_object_field<ClassLoaderData*>(to, java_lang_ClassLoader::loader_data_offset(), nullptr);
421   }
422 
423   size_t buffered_obj_offset = _buffer_used;
424   _buffer_used = new_used;
425 
426   return buffered_obj_offset;
427 }
428 
429 void ArchiveHeapWriter::set_requested_address(ArchiveHeapInfo* info) {
430   assert(!info->is_used(), "only set once");
431   assert(UseG1GC, "must be");
432   address heap_end = (address)G1CollectedHeap::heap()->reserved().end();
433   log_info(cds, heap)("Heap end = %p", heap_end);
434 
435   size_t heap_region_byte_size = _buffer_used;
436   assert(heap_region_byte_size > 0, "must archived at least one object!");
437 
438 
439   if (UseCompressedOops) {
440     _requested_bottom = align_down(heap_end - heap_region_byte_size, HeapRegion::GrainBytes);
441   } else {
442     // We always write the objects as if the heap started at this address. This
443     // makes the contents of the archive heap deterministic.
444     //
445     // Note that at runtime, the heap address is selected by the OS, so the archive
446     // heap will not be mapped at 0x10000000, and the contents need to be patched.
447     _requested_bottom = (address)NOCOOPS_REQUESTED_BASE;
448   }
449 
450   assert(is_aligned(_requested_bottom, HeapRegion::GrainBytes), "sanity");
451 
452   _requested_top = _requested_bottom + _buffer_used;
453 
454   info->set_buffer_region(MemRegion(offset_to_buffered_address<HeapWord*>(0),
455                                     offset_to_buffered_address<HeapWord*>(_buffer_used)));
456   info->set_heap_roots_offset(_heap_roots_offset);
457 }
458 
459 // Oop relocation
460 
461 template <typename T> T* ArchiveHeapWriter::requested_addr_to_buffered_addr(T* p) {
462   assert(is_in_requested_range(cast_to_oop(p)), "must be");
463 
464   address addr = address(p);
465   assert(addr >= _requested_bottom, "must be");
466   size_t offset = addr - _requested_bottom;
467   return offset_to_buffered_address<T*>(offset);
468 }
469 
470 template <typename T> oop ArchiveHeapWriter::load_source_oop_from_buffer(T* buffered_addr) {
471   oop o = load_oop_from_buffer(buffered_addr);
472   assert(!in_buffer(cast_from_oop<address>(o)), "must point to source oop");
473   return o;
474 }
475 
476 template <typename T> void ArchiveHeapWriter::store_requested_oop_in_buffer(T* buffered_addr,
477                                                                             oop request_oop) {
478   assert(is_in_requested_range(request_oop), "must be");
479   store_oop_in_buffer(buffered_addr, request_oop);
480 }
481 
482 inline void ArchiveHeapWriter::store_oop_in_buffer(oop* buffered_addr, oop requested_obj) {
483   *buffered_addr = requested_obj;
484 }
485 
486 inline void ArchiveHeapWriter::store_oop_in_buffer(narrowOop* buffered_addr, oop requested_obj) {
487   narrowOop val = CompressedOops::encode_not_null(requested_obj);
488   *buffered_addr = val;
489 }
490 
491 oop ArchiveHeapWriter::load_oop_from_buffer(oop* buffered_addr) {
492   return *buffered_addr;
493 }
494 
495 oop ArchiveHeapWriter::load_oop_from_buffer(narrowOop* buffered_addr) {
496   return CompressedOops::decode(*buffered_addr);
497 }
498 
499 template <typename T> void ArchiveHeapWriter::relocate_field_in_buffer(T* field_addr_in_buffer, CHeapBitMap* oopmap) {
500   oop source_referent = load_source_oop_from_buffer<T>(field_addr_in_buffer);
501   if (!CompressedOops::is_null(source_referent)) {
502     oop request_referent = source_obj_to_requested_obj(source_referent);
503     store_requested_oop_in_buffer<T>(field_addr_in_buffer, request_referent);
504     mark_oop_pointer<T>(field_addr_in_buffer, oopmap);
505   }
506 }
507 
508 template <typename T> void ArchiveHeapWriter::mark_oop_pointer(T* buffered_addr, CHeapBitMap* oopmap) {
509   T* request_p = (T*)(buffered_addr_to_requested_addr((address)buffered_addr));
510   address requested_region_bottom;
511 
512   assert(request_p >= (T*)_requested_bottom, "sanity");
513   assert(request_p <  (T*)_requested_top, "sanity");
514   requested_region_bottom = _requested_bottom;
515 
516   // Mark the pointer in the oopmap
517   T* region_bottom = (T*)requested_region_bottom;
518   assert(request_p >= region_bottom, "must be");
519   BitMap::idx_t idx = request_p - region_bottom;
520   assert(idx < oopmap->size(), "overflow");
521   oopmap->set_bit(idx);
522 }
523 
524 void ArchiveHeapWriter::update_header_for_requested_obj(oop requested_obj, oop src_obj,  Klass* src_klass) {
525   assert(UseCompressedClassPointers, "Archived heap only supported for compressed klasses");
526   narrowKlass nk = ArchiveBuilder::current()->get_requested_narrow_klass(src_klass);
527   address buffered_addr = requested_addr_to_buffered_addr(cast_from_oop<address>(requested_obj));
528 
529   oop fake_oop = cast_to_oop(buffered_addr);
530   fake_oop->set_narrow_klass(nk);
531 
532   // We need to retain the identity_hash, because it may have been used by some hashtables
533   // in the shared heap. This also has the side effect of pre-initializing the
534   // identity_hash for all shared objects, so they are less likely to be written
535   // into during run time, increasing the potential of memory sharing.
536   if (src_obj != nullptr) {
537     intptr_t src_hash = src_obj->identity_hash();
538     fake_oop->set_mark(markWord::prototype().copy_set_hash(src_hash));
539     assert(fake_oop->mark().is_unlocked(), "sanity");
540 
541     DEBUG_ONLY(intptr_t archived_hash = fake_oop->identity_hash());
542     assert(src_hash == archived_hash, "Different hash codes: original " INTPTR_FORMAT ", archived " INTPTR_FORMAT, src_hash, archived_hash);
543   }
544 }
545 
546 // Relocate an element in the buffered copy of HeapShared::roots()
547 template <typename T> void ArchiveHeapWriter::relocate_root_at(oop requested_roots, int index, CHeapBitMap* oopmap) {
548   size_t offset = (size_t)((objArrayOop)requested_roots)->obj_at_offset<T>(index);
549   relocate_field_in_buffer<T>((T*)(buffered_heap_roots_addr() + offset), oopmap);
550 }
551 
552 class ArchiveHeapWriter::EmbeddedOopRelocator: public BasicOopIterateClosure {
553   oop _src_obj;
554   address _buffered_obj;
555   CHeapBitMap* _oopmap;
556 
557 public:
558   EmbeddedOopRelocator(oop src_obj, address buffered_obj, CHeapBitMap* oopmap) :
559     _src_obj(src_obj), _buffered_obj(buffered_obj), _oopmap(oopmap) {}
560 
561   void do_oop(narrowOop *p) { EmbeddedOopRelocator::do_oop_work(p); }
562   void do_oop(      oop *p) { EmbeddedOopRelocator::do_oop_work(p); }
563 
564 private:
565   template <class T> void do_oop_work(T *p) {
566     size_t field_offset = pointer_delta(p, _src_obj, sizeof(char));
567     ArchiveHeapWriter::relocate_field_in_buffer<T>((T*)(_buffered_obj + field_offset), _oopmap);
568   }
569 };
570 
571 static void log_bitmap_usage(const char* which, BitMap* bitmap, size_t total_bits) {
572   // The whole heap is covered by total_bits, but there are only non-zero bits within [start ... end).
573   size_t start = bitmap->find_first_set_bit(0);
574   size_t end = bitmap->size();
575   log_info(cds)("%s = " SIZE_FORMAT_W(7) " ... " SIZE_FORMAT_W(7) " (%3zu%% ... %3zu%% = %3zu%%)", which,
576                 start, end,
577                 start * 100 / total_bits,
578                 end * 100 / total_bits,
579                 (end - start) * 100 / total_bits);
580 }
581 
582 // Update all oop fields embedded in the buffered objects
583 void ArchiveHeapWriter::relocate_embedded_oops(GrowableArrayCHeap<oop, mtClassShared>* roots,
584                                                ArchiveHeapInfo* heap_info) {
585   size_t oopmap_unit = (UseCompressedOops ? sizeof(narrowOop) : sizeof(oop));
586   size_t heap_region_byte_size = _buffer_used;
587   heap_info->oopmap()->resize(heap_region_byte_size   / oopmap_unit);
588 
589   for (int i = 0; i < _source_objs_order->length(); i++) {
590     int src_obj_index = _source_objs_order->at(i)._index;
591     oop src_obj = _source_objs->at(src_obj_index);
592     HeapShared::CachedOopInfo* info = HeapShared::archived_object_cache()->get(src_obj);
593     assert(info != nullptr, "must be");
594     oop requested_obj = requested_obj_from_buffer_offset(info->buffer_offset());
595     update_header_for_requested_obj(requested_obj, src_obj, src_obj->klass());
596     address buffered_obj = offset_to_buffered_address<address>(info->buffer_offset());
597     EmbeddedOopRelocator relocator(src_obj, buffered_obj, heap_info->oopmap());
598     src_obj->oop_iterate(&relocator);
599   };
600 
601   // Relocate HeapShared::roots(), which is created in copy_roots_to_buffer() and
602   // doesn't have a corresponding src_obj, so we can't use EmbeddedOopRelocator on it.
603   oop requested_roots = requested_obj_from_buffer_offset(_heap_roots_offset);
604   update_header_for_requested_obj(requested_roots, nullptr, Universe::objectArrayKlass());
605   int length = roots != nullptr ? roots->length() : 0;
606   for (int i = 0; i < length; i++) {
607     if (UseCompressedOops) {
608       relocate_root_at<narrowOop>(requested_roots, i, heap_info->oopmap());
609     } else {
610       relocate_root_at<oop>(requested_roots, i, heap_info->oopmap());
611     }
612   }
613 
614   compute_ptrmap(heap_info);
615 
616   size_t total_bytes = (size_t)_buffer->length();
617   log_bitmap_usage("oopmap", heap_info->oopmap(), total_bytes / (UseCompressedOops ? sizeof(narrowOop) : sizeof(oop)));
618   log_bitmap_usage("ptrmap", heap_info->ptrmap(), total_bytes / sizeof(address));
619 }
620 
621 void ArchiveHeapWriter::mark_native_pointer(oop src_obj, int field_offset) {
622   Metadata* ptr = src_obj->metadata_field_acquire(field_offset);
623   if (ptr != nullptr) {
624     NativePointerInfo info;
625     info._src_obj = src_obj;
626     info._field_offset = field_offset;
627     _native_pointers->append(info);
628     HeapShared::set_has_native_pointers(src_obj);
629     _num_native_ptrs ++;
630   }
631 }
632 
633 // Do we have a jlong/jint field that's actually a pointer to a MetaspaceObj?
634 bool ArchiveHeapWriter::is_marked_as_native_pointer(ArchiveHeapInfo* heap_info, oop src_obj, int field_offset) {
635   HeapShared::CachedOopInfo* p = HeapShared::archived_object_cache()->get(src_obj);
636   assert(p != nullptr, "must be");
637 
638   // requested_field_addr = the address of this field in the requested space
639   oop requested_obj = requested_obj_from_buffer_offset(p->buffer_offset());
640   Metadata** requested_field_addr = (Metadata**)(cast_from_oop<address>(requested_obj) + field_offset);
641   assert((Metadata**)_requested_bottom <= requested_field_addr && requested_field_addr < (Metadata**) _requested_top, "range check");
642 
643   BitMap::idx_t idx = requested_field_addr - (Metadata**) _requested_bottom;
644   // Leading zeros have been removed so some addresses may not be in the ptrmap
645   size_t start_pos = FileMapInfo::current_info()->heap_ptrmap_start_pos();
646   if (idx < start_pos) {
647     return false;
648   } else {
649     idx -= start_pos;
650   }
651   return (idx < heap_info->ptrmap()->size()) && (heap_info->ptrmap()->at(idx) == true);
652 }
653 
654 void ArchiveHeapWriter::compute_ptrmap(ArchiveHeapInfo* heap_info) {
655   int num_non_null_ptrs = 0;
656   Metadata** bottom = (Metadata**) _requested_bottom;
657   Metadata** top = (Metadata**) _requested_top; // exclusive
658   heap_info->ptrmap()->resize(top - bottom);
659 
660   BitMap::idx_t max_idx = 32; // paranoid - don't make it too small
661   for (int i = 0; i < _native_pointers->length(); i++) {
662     NativePointerInfo info = _native_pointers->at(i);
663     oop src_obj = info._src_obj;
664     int field_offset = info._field_offset;
665     HeapShared::CachedOopInfo* p = HeapShared::archived_object_cache()->get(src_obj);
666     // requested_field_addr = the address of this field in the requested space
667     oop requested_obj = requested_obj_from_buffer_offset(p->buffer_offset());
668     Metadata** requested_field_addr = (Metadata**)(cast_from_oop<address>(requested_obj) + field_offset);
669     assert(bottom <= requested_field_addr && requested_field_addr < top, "range check");
670 
671     // Mark this field in the bitmap
672     BitMap::idx_t idx = requested_field_addr - bottom;
673     heap_info->ptrmap()->set_bit(idx);
674     num_non_null_ptrs ++;
675     max_idx = MAX2(max_idx, idx);
676 
677     // Set the native pointer to the requested address of the metadata (at runtime, the metadata will have
678     // this address if the RO/RW regions are mapped at the default location).
679 
680     Metadata** buffered_field_addr = requested_addr_to_buffered_addr(requested_field_addr);
681     Metadata* native_ptr = *buffered_field_addr;
682     assert(native_ptr != nullptr, "sanity");
683 
684     address buffered_native_ptr = ArchiveBuilder::current()->get_buffered_addr((address)native_ptr);
685     address requested_native_ptr = ArchiveBuilder::current()->to_requested(buffered_native_ptr);
686     *buffered_field_addr = (Metadata*)requested_native_ptr;
687   }
688 
689   heap_info->ptrmap()->resize(max_idx + 1);
690   log_info(cds, heap)("calculate_ptrmap: marked %d non-null native pointers for heap region (" SIZE_FORMAT " bits)",
691                       num_non_null_ptrs, size_t(heap_info->ptrmap()->size()));
692 }
693 
694 #endif // INCLUDE_CDS_JAVA_HEAP