1 /*
  2  * Copyright (c) 2023, 2025, 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 "cds/aotReferenceObjSupport.hpp"
 26 #include "cds/archiveHeapWriter.hpp"
 27 #include "cds/cdsConfig.hpp"
 28 #include "cds/filemap.hpp"
 29 #include "cds/heapShared.hpp"
 30 #include "cds/regeneratedClasses.hpp"
 31 #include "classfile/javaClasses.hpp"
 32 #include "classfile/modules.hpp"
 33 #include "classfile/systemDictionary.hpp"
 34 #include "gc/shared/collectedHeap.hpp"
 35 #include "memory/iterator.inline.hpp"
 36 #include "memory/oopFactory.hpp"
 37 #include "memory/universe.hpp"
 38 #include "oops/compressedOops.hpp"
 39 #include "oops/objArrayOop.inline.hpp"
 40 #include "oops/oop.inline.hpp"
 41 #include "oops/oopHandle.inline.hpp"
 42 #include "oops/typeArrayKlass.hpp"
 43 #include "oops/typeArrayOop.hpp"
 44 #include "runtime/java.hpp"
 45 #include "runtime/mutexLocker.hpp"
 46 #include "utilities/bitMap.inline.hpp"
 47 #if INCLUDE_G1GC
 48 #include "gc/g1/g1CollectedHeap.hpp"
 49 #include "gc/g1/g1HeapRegion.hpp"
 50 #endif
 51 
 52 #if INCLUDE_CDS_JAVA_HEAP
 53 
 54 GrowableArrayCHeap<u1, mtClassShared>* ArchiveHeapWriter::_buffer = nullptr;
 55 
 56 // The following are offsets from buffer_bottom()
 57 size_t ArchiveHeapWriter::_buffer_used;
 58 
 59 // Heap root segments
 60 HeapRootSegments ArchiveHeapWriter::_heap_root_segments;
 61 
 62 address ArchiveHeapWriter::_requested_bottom;
 63 address ArchiveHeapWriter::_requested_top;
 64 
 65 GrowableArrayCHeap<ArchiveHeapWriter::NativePointerInfo, mtClassShared>* ArchiveHeapWriter::_native_pointers;
 66 GrowableArrayCHeap<oop, mtClassShared>* ArchiveHeapWriter::_source_objs;
 67 GrowableArrayCHeap<ArchiveHeapWriter::HeapObjOrder, mtClassShared>* ArchiveHeapWriter::_source_objs_order;
 68 
 69 ArchiveHeapWriter::BufferOffsetToSourceObjectTable*
 70   ArchiveHeapWriter::_buffer_offset_to_source_obj_table = nullptr;
 71 
 72 
 73 typedef HashTable<
 74       size_t,    // offset of a filler from ArchiveHeapWriter::buffer_bottom()
 75       size_t,    // size of this filler (in bytes)
 76       127,       // prime number
 77       AnyObj::C_HEAP,
 78       mtClassShared> FillersTable;
 79 static FillersTable* _fillers;
 80 static int _num_native_ptrs = 0;
 81 
 82 void ArchiveHeapWriter::init() {
 83   if (CDSConfig::is_dumping_heap()) {
 84     Universe::heap()->collect(GCCause::_java_lang_system_gc);
 85 
 86     _buffer_offset_to_source_obj_table = new BufferOffsetToSourceObjectTable(/*size (prime)*/36137, /*max size*/1 * M);
 87     _fillers = new FillersTable();
 88     _requested_bottom = nullptr;
 89     _requested_top = nullptr;
 90 
 91     _native_pointers = new GrowableArrayCHeap<NativePointerInfo, mtClassShared>(2048);
 92     _source_objs = new GrowableArrayCHeap<oop, mtClassShared>(10000);
 93 
 94     guarantee(MIN_GC_REGION_ALIGNMENT <= G1HeapRegion::min_region_size_in_words() * HeapWordSize, "must be");
 95   }
 96 }
 97 
 98 void ArchiveHeapWriter::add_source_obj(oop src_obj) {
 99   _source_objs->append(src_obj);
100 }
101 
102 void ArchiveHeapWriter::write(GrowableArrayCHeap<oop, mtClassShared>* roots,
103                               ArchiveHeapInfo* heap_info) {
104   assert(CDSConfig::is_dumping_heap(), "sanity");
105   allocate_buffer();
106   copy_source_objs_to_buffer(roots);
107   set_requested_address(heap_info);
108   relocate_embedded_oops(roots, heap_info);
109 }
110 
111 bool ArchiveHeapWriter::is_too_large_to_archive(oop o) {
112   return is_too_large_to_archive(o->size());
113 }
114 
115 bool ArchiveHeapWriter::is_string_too_large_to_archive(oop string) {
116   typeArrayOop value = java_lang_String::value_no_keepalive(string);
117   return is_too_large_to_archive(value);
118 }
119 
120 bool ArchiveHeapWriter::is_too_large_to_archive(size_t size) {
121   assert(size > 0, "no zero-size object");
122   assert(size * HeapWordSize > size, "no overflow");
123   static_assert(MIN_GC_REGION_ALIGNMENT > 0, "must be positive");
124 
125   size_t byte_size = size * HeapWordSize;
126   if (byte_size > size_t(MIN_GC_REGION_ALIGNMENT)) {
127     return true;
128   } else {
129     return false;
130   }
131 }
132 
133 // Various lookup functions between source_obj, buffered_obj and requested_obj
134 bool ArchiveHeapWriter::is_in_requested_range(oop o) {
135   assert(_requested_bottom != nullptr, "do not call before _requested_bottom is initialized");
136   address a = cast_from_oop<address>(o);
137   return (_requested_bottom <= a && a < _requested_top);
138 }
139 
140 oop ArchiveHeapWriter::requested_obj_from_buffer_offset(size_t offset) {
141   oop req_obj = cast_to_oop(_requested_bottom + offset);
142   assert(is_in_requested_range(req_obj), "must be");
143   return req_obj;
144 }
145 
146 oop ArchiveHeapWriter::source_obj_to_requested_obj(oop src_obj) {
147   assert(CDSConfig::is_dumping_heap(), "dump-time only");
148   HeapShared::CachedOopInfo* p = HeapShared::archived_object_cache()->get(src_obj);
149   if (p != nullptr) {
150     return requested_obj_from_buffer_offset(p->buffer_offset());
151   } else {
152     return nullptr;
153   }
154 }
155 
156 oop ArchiveHeapWriter::buffered_addr_to_source_obj(address buffered_addr) {
157   oop* p = _buffer_offset_to_source_obj_table->get(buffered_address_to_offset(buffered_addr));
158   if (p != nullptr) {
159     return *p;
160   } else {
161     return nullptr;
162   }
163 }
164 
165 Klass* ArchiveHeapWriter::real_klass_of_buffered_oop(address buffered_addr) {
166   oop p = buffered_addr_to_source_obj(buffered_addr);
167   if (p != nullptr) {
168     return p->klass();
169   } else if (get_filler_size_at(buffered_addr) > 0) {
170     return Universe::fillerArrayKlass();
171   } else {
172     // This is one of the root segments
173     return Universe::objectArrayKlass();
174   }
175 }
176 
177 size_t ArchiveHeapWriter::size_of_buffered_oop(address buffered_addr) {
178   oop p = buffered_addr_to_source_obj(buffered_addr);
179   if (p != nullptr) {
180     return p->size();
181   }
182 
183   size_t nbytes = get_filler_size_at(buffered_addr);
184   if (nbytes > 0) {
185     assert((nbytes % BytesPerWord) == 0, "should be aligned");
186     return nbytes / BytesPerWord;
187   }
188 
189   address hrs = buffer_bottom();
190   for (size_t seg_idx = 0; seg_idx < _heap_root_segments.count(); seg_idx++) {
191     nbytes = _heap_root_segments.size_in_bytes(seg_idx);
192     if (hrs == buffered_addr) {
193       assert((nbytes % BytesPerWord) == 0, "should be aligned");
194       return nbytes / BytesPerWord;
195     }
196     hrs += nbytes;
197   }
198 
199   ShouldNotReachHere();
200   return 0;
201 }
202 
203 address ArchiveHeapWriter::buffered_addr_to_requested_addr(address buffered_addr) {
204   return _requested_bottom + buffered_address_to_offset(buffered_addr);
205 }
206 
207 address ArchiveHeapWriter::requested_address() {
208   assert(_buffer != nullptr, "must be initialized");
209   return _requested_bottom;
210 }
211 
212 void ArchiveHeapWriter::allocate_buffer() {
213   int initial_buffer_size = 100000;
214   _buffer = new GrowableArrayCHeap<u1, mtClassShared>(initial_buffer_size);
215   _buffer_used = 0;
216   ensure_buffer_space(1); // so that buffer_bottom() works
217 }
218 
219 void ArchiveHeapWriter::ensure_buffer_space(size_t min_bytes) {
220   // We usually have very small heaps. If we get a huge one it's probably caused by a bug.
221   guarantee(min_bytes <= max_jint, "we dont support archiving more than 2G of objects");
222   _buffer->at_grow(to_array_index(min_bytes));
223 }
224 
225 objArrayOop ArchiveHeapWriter::allocate_root_segment(size_t offset, int element_count) {
226   HeapWord* mem = offset_to_buffered_address<HeapWord *>(offset);
227   memset(mem, 0, objArrayOopDesc::object_size(element_count));
228 
229   // The initialization code is copied from MemAllocator::finish and ObjArrayAllocator::initialize.
230   if (UseCompactObjectHeaders) {
231     oopDesc::release_set_mark(mem, Universe::objectArrayKlass()->prototype_header());
232   } else {
233     oopDesc::set_mark(mem, markWord::prototype());
234     oopDesc::release_set_klass(mem, Universe::objectArrayKlass());
235   }
236   arrayOopDesc::set_length(mem, element_count);
237   return objArrayOop(cast_to_oop(mem));
238 }
239 
240 void ArchiveHeapWriter::root_segment_at_put(objArrayOop segment, int index, oop root) {
241   // Do not use arrayOop->obj_at_put(i, o) as arrayOop is outside the real heap!
242   if (UseCompressedOops) {
243     *segment->obj_at_addr<narrowOop>(index) = CompressedOops::encode(root);
244   } else {
245     *segment->obj_at_addr<oop>(index) = root;
246   }
247 }
248 
249 void ArchiveHeapWriter::copy_roots_to_buffer(GrowableArrayCHeap<oop, mtClassShared>* roots) {
250   // Depending on the number of classes we are archiving, a single roots array may be
251   // larger than MIN_GC_REGION_ALIGNMENT. Roots are allocated first in the buffer, which
252   // allows us to chop the large array into a series of "segments". Current layout
253   // starts with zero or more segments exactly fitting MIN_GC_REGION_ALIGNMENT, and end
254   // with a single segment that may be smaller than MIN_GC_REGION_ALIGNMENT.
255   // This is simple and efficient. We do not need filler objects anywhere between the segments,
256   // or immediately after the last segment. This allows starting the object dump immediately
257   // after the roots.
258 
259   assert((_buffer_used % MIN_GC_REGION_ALIGNMENT) == 0,
260          "Pre-condition: Roots start at aligned boundary: %zu", _buffer_used);
261 
262   int max_elem_count = ((MIN_GC_REGION_ALIGNMENT - arrayOopDesc::header_size_in_bytes()) / heapOopSize);
263   assert(objArrayOopDesc::object_size(max_elem_count)*HeapWordSize == MIN_GC_REGION_ALIGNMENT,
264          "Should match exactly");
265 
266   HeapRootSegments segments(_buffer_used,
267                             roots->length(),
268                             MIN_GC_REGION_ALIGNMENT,
269                             max_elem_count);
270 
271   int root_index = 0;
272   for (size_t seg_idx = 0; seg_idx < segments.count(); seg_idx++) {
273     int size_elems = segments.size_in_elems(seg_idx);
274     size_t size_bytes = segments.size_in_bytes(seg_idx);
275 
276     size_t oop_offset = _buffer_used;
277     _buffer_used = oop_offset + size_bytes;
278     ensure_buffer_space(_buffer_used);
279 
280     assert((oop_offset % MIN_GC_REGION_ALIGNMENT) == 0,
281            "Roots segment %zu start is not aligned: %zu",
282            segments.count(), oop_offset);
283 
284     objArrayOop seg_oop = allocate_root_segment(oop_offset, size_elems);
285     for (int i = 0; i < size_elems; i++) {
286       root_segment_at_put(seg_oop, i, roots->at(root_index++));
287     }
288 
289     log_info(aot, heap)("archived obj root segment [%d] = %zu bytes, obj = " PTR_FORMAT,
290                         size_elems, size_bytes, p2i(seg_oop));
291   }
292 
293   assert(root_index == roots->length(), "Post-condition: All roots are handled");
294 
295   _heap_root_segments = segments;
296 }
297 
298 // The goal is to sort the objects in increasing order of:
299 // - objects that have only oop pointers
300 // - objects that have both native and oop pointers
301 // - objects that have only native pointers
302 // - objects that have no pointers
303 static int oop_sorting_rank(oop o) {
304   bool has_oop_ptr, has_native_ptr;
305   HeapShared::get_pointer_info(o, has_oop_ptr, has_native_ptr);
306 
307   if (has_oop_ptr) {
308     if (!has_native_ptr) {
309       return 0;
310     } else {
311       return 1;
312     }
313   } else {
314     if (has_native_ptr) {
315       return 2;
316     } else {
317       return 3;
318     }
319   }
320 }
321 
322 int ArchiveHeapWriter::compare_objs_by_oop_fields(HeapObjOrder* a, HeapObjOrder* b) {
323   int rank_a = a->_rank;
324   int rank_b = b->_rank;
325 
326   if (rank_a != rank_b) {
327     return rank_a - rank_b;
328   } else {
329     // If they are the same rank, sort them by their position in the _source_objs array
330     return a->_index - b->_index;
331   }
332 }
333 
334 void ArchiveHeapWriter::sort_source_objs() {
335   log_info(aot)("sorting heap objects");
336   int len = _source_objs->length();
337   _source_objs_order = new GrowableArrayCHeap<HeapObjOrder, mtClassShared>(len);
338 
339   for (int i = 0; i < len; i++) {
340     oop o = _source_objs->at(i);
341     int rank = oop_sorting_rank(o);
342     HeapObjOrder os = {i, rank};
343     _source_objs_order->append(os);
344   }
345   log_info(aot)("computed ranks");
346   _source_objs_order->sort(compare_objs_by_oop_fields);
347   log_info(aot)("sorting heap objects done");
348 }
349 
350 void ArchiveHeapWriter::copy_source_objs_to_buffer(GrowableArrayCHeap<oop, mtClassShared>* roots) {
351   // There could be multiple root segments, which we want to be aligned by region.
352   // Putting them ahead of objects makes sure we waste no space.
353   copy_roots_to_buffer(roots);
354 
355   sort_source_objs();
356   for (int i = 0; i < _source_objs_order->length(); i++) {
357     int src_obj_index = _source_objs_order->at(i)._index;
358     oop src_obj = _source_objs->at(src_obj_index);
359     HeapShared::CachedOopInfo* info = HeapShared::archived_object_cache()->get(src_obj);
360     assert(info != nullptr, "must be");
361     size_t buffer_offset = copy_one_source_obj_to_buffer(src_obj);
362     info->set_buffer_offset(buffer_offset);
363 
364     _buffer_offset_to_source_obj_table->put_when_absent(buffer_offset, src_obj);
365     _buffer_offset_to_source_obj_table->maybe_grow();
366 
367     if (java_lang_Module::is_instance(src_obj)) {
368       Modules::check_archived_module_oop(src_obj);
369     }
370   }
371 
372   log_info(aot)("Size of heap region = %zu bytes, %d objects, %d roots, %d native ptrs",
373                 _buffer_used, _source_objs->length() + 1, roots->length(), _num_native_ptrs);
374 }
375 
376 size_t ArchiveHeapWriter::filler_array_byte_size(int length) {
377   size_t byte_size = objArrayOopDesc::object_size(length) * HeapWordSize;
378   return byte_size;
379 }
380 
381 int ArchiveHeapWriter::filler_array_length(size_t fill_bytes) {
382   assert(is_object_aligned(fill_bytes), "must be");
383   size_t elemSize = (UseCompressedOops ? sizeof(narrowOop) : sizeof(oop));
384 
385   int initial_length = to_array_length(fill_bytes / elemSize);
386   for (int length = initial_length; length >= 0; length --) {
387     size_t array_byte_size = filler_array_byte_size(length);
388     if (array_byte_size == fill_bytes) {
389       return length;
390     }
391   }
392 
393   ShouldNotReachHere();
394   return -1;
395 }
396 
397 HeapWord* ArchiveHeapWriter::init_filler_array_at_buffer_top(int array_length, size_t fill_bytes) {
398   assert(UseCompressedClassPointers, "Archived heap only supported for compressed klasses");
399   Klass* oak = Universe::objectArrayKlass(); // already relocated to point to archived klass
400   HeapWord* mem = offset_to_buffered_address<HeapWord*>(_buffer_used);
401   memset(mem, 0, fill_bytes);
402   narrowKlass nk = ArchiveBuilder::current()->get_requested_narrow_klass(oak);
403   if (UseCompactObjectHeaders) {
404     oopDesc::release_set_mark(mem, markWord::prototype().set_narrow_klass(nk));
405   } else {
406     oopDesc::set_mark(mem, markWord::prototype());
407     cast_to_oop(mem)->set_narrow_klass(nk);
408   }
409   arrayOopDesc::set_length(mem, array_length);
410   return mem;
411 }
412 
413 void ArchiveHeapWriter::maybe_fill_gc_region_gap(size_t required_byte_size) {
414   // We fill only with arrays (so we don't need to use a single HeapWord filler if the
415   // leftover space is smaller than a zero-sized array object). Therefore, we need to
416   // make sure there's enough space of min_filler_byte_size in the current region after
417   // required_byte_size has been allocated. If not, fill the remainder of the current
418   // region.
419   size_t min_filler_byte_size = filler_array_byte_size(0);
420   size_t new_used = _buffer_used + required_byte_size + min_filler_byte_size;
421 
422   const size_t cur_min_region_bottom = align_down(_buffer_used, MIN_GC_REGION_ALIGNMENT);
423   const size_t next_min_region_bottom = align_down(new_used, MIN_GC_REGION_ALIGNMENT);
424 
425   if (cur_min_region_bottom != next_min_region_bottom) {
426     // Make sure that no objects span across MIN_GC_REGION_ALIGNMENT. This way
427     // we can map the region in any region-based collector.
428     assert(next_min_region_bottom > cur_min_region_bottom, "must be");
429     assert(next_min_region_bottom - cur_min_region_bottom == MIN_GC_REGION_ALIGNMENT,
430            "no buffered object can be larger than %d bytes",  MIN_GC_REGION_ALIGNMENT);
431 
432     const size_t filler_end = next_min_region_bottom;
433     const size_t fill_bytes = filler_end - _buffer_used;
434     assert(fill_bytes > 0, "must be");
435     ensure_buffer_space(filler_end);
436 
437     int array_length = filler_array_length(fill_bytes);
438     log_info(aot, heap)("Inserting filler obj array of %d elements (%zu bytes total) @ buffer offset %zu",
439                         array_length, fill_bytes, _buffer_used);
440     HeapWord* filler = init_filler_array_at_buffer_top(array_length, fill_bytes);
441     _buffer_used = filler_end;
442     _fillers->put(buffered_address_to_offset((address)filler), fill_bytes);
443   }
444 }
445 
446 size_t ArchiveHeapWriter::get_filler_size_at(address buffered_addr) {
447   size_t* p = _fillers->get(buffered_address_to_offset(buffered_addr));
448   if (p != nullptr) {
449     assert(*p > 0, "filler must be larger than zero bytes");
450     return *p;
451   } else {
452     return 0; // buffered_addr is not a filler
453   }
454 }
455 
456 template <typename T>
457 void update_buffered_object_field(address buffered_obj, int field_offset, T value) {
458   T* field_addr = cast_to_oop(buffered_obj)->field_addr<T>(field_offset);
459   *field_addr = value;
460 }
461 
462 size_t ArchiveHeapWriter::copy_one_source_obj_to_buffer(oop src_obj) {
463   assert(!is_too_large_to_archive(src_obj), "already checked");
464   size_t byte_size = src_obj->size() * HeapWordSize;
465   assert(byte_size > 0, "no zero-size objects");
466 
467   // For region-based collectors such as G1, the archive heap may be mapped into
468   // multiple regions. We need to make sure that we don't have an object that can possible
469   // span across two regions.
470   maybe_fill_gc_region_gap(byte_size);
471 
472   size_t new_used = _buffer_used + byte_size;
473   assert(new_used > _buffer_used, "no wrap around");
474 
475   size_t cur_min_region_bottom = align_down(_buffer_used, MIN_GC_REGION_ALIGNMENT);
476   size_t next_min_region_bottom = align_down(new_used, MIN_GC_REGION_ALIGNMENT);
477   assert(cur_min_region_bottom == next_min_region_bottom, "no object should cross minimal GC region boundaries");
478 
479   ensure_buffer_space(new_used);
480 
481   address from = cast_from_oop<address>(src_obj);
482   address to = offset_to_buffered_address<address>(_buffer_used);
483   assert(is_object_aligned(_buffer_used), "sanity");
484   assert(is_object_aligned(byte_size), "sanity");
485   memcpy(to, from, byte_size);
486 
487   // These native pointers will be restored explicitly at run time.
488   if (java_lang_Module::is_instance(src_obj)) {
489     update_buffered_object_field<ModuleEntry*>(to, java_lang_Module::module_entry_offset(), nullptr);
490   } else if (java_lang_ClassLoader::is_instance(src_obj)) {
491 #ifdef ASSERT
492     // We only archive these loaders
493     if (src_obj != SystemDictionary::java_platform_loader() &&
494         src_obj != SystemDictionary::java_system_loader()) {
495       assert(src_obj->klass()->name()->equals("jdk/internal/loader/ClassLoaders$BootClassLoader"), "must be");
496     }
497 #endif
498     update_buffered_object_field<ClassLoaderData*>(to, java_lang_ClassLoader::loader_data_offset(), nullptr);
499   }
500 
501   size_t buffered_obj_offset = _buffer_used;
502   _buffer_used = new_used;
503 
504   return buffered_obj_offset;
505 }
506 
507 void ArchiveHeapWriter::set_requested_address(ArchiveHeapInfo* info) {
508   assert(!info->is_used(), "only set once");
509 
510   size_t heap_region_byte_size = _buffer_used;
511   assert(heap_region_byte_size > 0, "must archived at least one object!");
512 
513   if (UseCompressedOops) {
514     if (UseG1GC) {
515       address heap_end = (address)G1CollectedHeap::heap()->reserved().end();
516       log_info(aot, heap)("Heap end = %p", heap_end);
517       _requested_bottom = align_down(heap_end - heap_region_byte_size, G1HeapRegion::GrainBytes);
518       _requested_bottom = align_down(_requested_bottom, MIN_GC_REGION_ALIGNMENT);
519       assert(is_aligned(_requested_bottom, G1HeapRegion::GrainBytes), "sanity");
520     } else {
521       _requested_bottom = align_up(CompressedOops::begin(), MIN_GC_REGION_ALIGNMENT);
522     }
523   } else {
524     // We always write the objects as if the heap started at this address. This
525     // makes the contents of the archive heap deterministic.
526     //
527     // Note that at runtime, the heap address is selected by the OS, so the archive
528     // heap will not be mapped at 0x10000000, and the contents need to be patched.
529     _requested_bottom = align_up((address)NOCOOPS_REQUESTED_BASE, MIN_GC_REGION_ALIGNMENT);
530   }
531 
532   assert(is_aligned(_requested_bottom, MIN_GC_REGION_ALIGNMENT), "sanity");
533 
534   _requested_top = _requested_bottom + _buffer_used;
535 
536   info->set_buffer_region(MemRegion(offset_to_buffered_address<HeapWord*>(0),
537                                     offset_to_buffered_address<HeapWord*>(_buffer_used)));
538   info->set_heap_root_segments(_heap_root_segments);
539 }
540 
541 // Oop relocation
542 
543 template <typename T> T* ArchiveHeapWriter::requested_addr_to_buffered_addr(T* p) {
544   assert(is_in_requested_range(cast_to_oop(p)), "must be");
545 
546   address addr = address(p);
547   assert(addr >= _requested_bottom, "must be");
548   size_t offset = addr - _requested_bottom;
549   return offset_to_buffered_address<T*>(offset);
550 }
551 
552 template <typename T> oop ArchiveHeapWriter::load_source_oop_from_buffer(T* buffered_addr) {
553   oop o = load_oop_from_buffer(buffered_addr);
554   assert(!in_buffer(cast_from_oop<address>(o)), "must point to source oop");
555   return o;
556 }
557 
558 template <typename T> void ArchiveHeapWriter::store_requested_oop_in_buffer(T* buffered_addr,
559                                                                             oop request_oop) {
560   assert(is_in_requested_range(request_oop), "must be");
561   store_oop_in_buffer(buffered_addr, request_oop);
562 }
563 
564 inline void ArchiveHeapWriter::store_oop_in_buffer(oop* buffered_addr, oop requested_obj) {
565   *buffered_addr = requested_obj;
566 }
567 
568 inline void ArchiveHeapWriter::store_oop_in_buffer(narrowOop* buffered_addr, oop requested_obj) {
569   narrowOop val = CompressedOops::encode_not_null(requested_obj);
570   *buffered_addr = val;
571 }
572 
573 oop ArchiveHeapWriter::load_oop_from_buffer(oop* buffered_addr) {
574   return *buffered_addr;
575 }
576 
577 oop ArchiveHeapWriter::load_oop_from_buffer(narrowOop* buffered_addr) {
578   return CompressedOops::decode(*buffered_addr);
579 }
580 
581 template <typename T> void ArchiveHeapWriter::relocate_field_in_buffer(T* field_addr_in_buffer, CHeapBitMap* oopmap) {
582   oop source_referent = load_source_oop_from_buffer<T>(field_addr_in_buffer);
583   if (source_referent != nullptr) {
584     if (java_lang_Class::is_instance(source_referent)) {
585       Klass* k = java_lang_Class::as_Klass(source_referent);
586       if (RegeneratedClasses::has_been_regenerated(k)) {
587         source_referent = RegeneratedClasses::get_regenerated_object(k)->java_mirror();
588       }
589       // When the source object points to a "real" mirror, the buffered object should point
590       // to the "scratch" mirror, which has all unarchivable fields scrubbed (to be reinstated
591       // at run time).
592       source_referent = HeapShared::scratch_java_mirror(source_referent);
593       assert(source_referent != nullptr, "must be");
594     }
595     oop request_referent = source_obj_to_requested_obj(source_referent);
596     store_requested_oop_in_buffer<T>(field_addr_in_buffer, request_referent);
597     mark_oop_pointer<T>(field_addr_in_buffer, oopmap);
598   }
599 }
600 
601 template <typename T> void ArchiveHeapWriter::mark_oop_pointer(T* buffered_addr, CHeapBitMap* oopmap) {
602   T* request_p = (T*)(buffered_addr_to_requested_addr((address)buffered_addr));
603   address requested_region_bottom;
604 
605   assert(request_p >= (T*)_requested_bottom, "sanity");
606   assert(request_p <  (T*)_requested_top, "sanity");
607   requested_region_bottom = _requested_bottom;
608 
609   // Mark the pointer in the oopmap
610   T* region_bottom = (T*)requested_region_bottom;
611   assert(request_p >= region_bottom, "must be");
612   BitMap::idx_t idx = request_p - region_bottom;
613   assert(idx < oopmap->size(), "overflow");
614   oopmap->set_bit(idx);
615 }
616 
617 void ArchiveHeapWriter::update_header_for_requested_obj(oop requested_obj, oop src_obj,  Klass* src_klass) {
618   assert(UseCompressedClassPointers, "Archived heap only supported for compressed klasses");
619   narrowKlass nk = ArchiveBuilder::current()->get_requested_narrow_klass(src_klass);
620   address buffered_addr = requested_addr_to_buffered_addr(cast_from_oop<address>(requested_obj));
621 
622   oop fake_oop = cast_to_oop(buffered_addr);
623   if (UseCompactObjectHeaders) {
624     fake_oop->set_mark(markWord::prototype().set_narrow_klass(nk));
625   } else {
626     fake_oop->set_narrow_klass(nk);
627   }
628 
629   if (src_obj == nullptr) {
630     return;
631   }
632   // We need to retain the identity_hash, because it may have been used by some hashtables
633   // in the shared heap.
634   if (!src_obj->fast_no_hash_check()) {
635     intptr_t src_hash = src_obj->identity_hash();
636     if (UseCompactObjectHeaders) {
637       fake_oop->set_mark(markWord::prototype().set_narrow_klass(nk).copy_set_hash(src_hash));
638     } else {
639       fake_oop->set_mark(markWord::prototype().copy_set_hash(src_hash));
640     }
641     assert(fake_oop->mark().is_unlocked(), "sanity");
642 
643     DEBUG_ONLY(intptr_t archived_hash = fake_oop->identity_hash());
644     assert(src_hash == archived_hash, "Different hash codes: original " INTPTR_FORMAT ", archived " INTPTR_FORMAT, src_hash, archived_hash);
645   }
646   // Strip age bits.
647   fake_oop->set_mark(fake_oop->mark().set_age(0));
648 }
649 
650 class ArchiveHeapWriter::EmbeddedOopRelocator: public BasicOopIterateClosure {
651   oop _src_obj;
652   address _buffered_obj;
653   CHeapBitMap* _oopmap;
654   bool _is_java_lang_ref;
655 public:
656   EmbeddedOopRelocator(oop src_obj, address buffered_obj, CHeapBitMap* oopmap) :
657     _src_obj(src_obj), _buffered_obj(buffered_obj), _oopmap(oopmap)
658   {
659     _is_java_lang_ref = AOTReferenceObjSupport::check_if_ref_obj(src_obj);
660   }
661 
662   void do_oop(narrowOop *p) { EmbeddedOopRelocator::do_oop_work(p); }
663   void do_oop(      oop *p) { EmbeddedOopRelocator::do_oop_work(p); }
664 
665 private:
666   template <class T> void do_oop_work(T *p) {
667     int field_offset = pointer_delta_as_int((char*)p, cast_from_oop<char*>(_src_obj));
668     T* field_addr = (T*)(_buffered_obj + field_offset);
669     if (_is_java_lang_ref && AOTReferenceObjSupport::skip_field(field_offset)) {
670       // Do not copy these fields. Set them to null
671       *field_addr = (T)0x0;
672     } else {
673       ArchiveHeapWriter::relocate_field_in_buffer<T>(field_addr, _oopmap);
674     }
675   }
676 };
677 
678 static void log_bitmap_usage(const char* which, BitMap* bitmap, size_t total_bits) {
679   // The whole heap is covered by total_bits, but there are only non-zero bits within [start ... end).
680   size_t start = bitmap->find_first_set_bit(0);
681   size_t end = bitmap->size();
682   log_info(aot)("%s = %7zu ... %7zu (%3zu%% ... %3zu%% = %3zu%%)", which,
683                 start, end,
684                 start * 100 / total_bits,
685                 end * 100 / total_bits,
686                 (end - start) * 100 / total_bits);
687 }
688 
689 // Update all oop fields embedded in the buffered objects
690 void ArchiveHeapWriter::relocate_embedded_oops(GrowableArrayCHeap<oop, mtClassShared>* roots,
691                                                ArchiveHeapInfo* heap_info) {
692   size_t oopmap_unit = (UseCompressedOops ? sizeof(narrowOop) : sizeof(oop));
693   size_t heap_region_byte_size = _buffer_used;
694   heap_info->oopmap()->resize(heap_region_byte_size   / oopmap_unit);
695 
696   for (int i = 0; i < _source_objs_order->length(); i++) {
697     int src_obj_index = _source_objs_order->at(i)._index;
698     oop src_obj = _source_objs->at(src_obj_index);
699     HeapShared::CachedOopInfo* info = HeapShared::archived_object_cache()->get(src_obj);
700     assert(info != nullptr, "must be");
701     oop requested_obj = requested_obj_from_buffer_offset(info->buffer_offset());
702     update_header_for_requested_obj(requested_obj, src_obj, src_obj->klass());
703     address buffered_obj = offset_to_buffered_address<address>(info->buffer_offset());
704     EmbeddedOopRelocator relocator(src_obj, buffered_obj, heap_info->oopmap());
705     src_obj->oop_iterate(&relocator);
706   };
707 
708   // Relocate HeapShared::roots(), which is created in copy_roots_to_buffer() and
709   // doesn't have a corresponding src_obj, so we can't use EmbeddedOopRelocator on it.
710   for (size_t seg_idx = 0; seg_idx < _heap_root_segments.count(); seg_idx++) {
711     size_t seg_offset = _heap_root_segments.segment_offset(seg_idx);
712 
713     objArrayOop requested_obj = (objArrayOop)requested_obj_from_buffer_offset(seg_offset);
714     update_header_for_requested_obj(requested_obj, nullptr, Universe::objectArrayKlass());
715     address buffered_obj = offset_to_buffered_address<address>(seg_offset);
716     int length = _heap_root_segments.size_in_elems(seg_idx);
717 
718     if (UseCompressedOops) {
719       for (int i = 0; i < length; i++) {
720         narrowOop* addr = (narrowOop*)(buffered_obj + objArrayOopDesc::obj_at_offset<narrowOop>(i));
721         relocate_field_in_buffer<narrowOop>(addr, heap_info->oopmap());
722       }
723     } else {
724       for (int i = 0; i < length; i++) {
725         oop* addr = (oop*)(buffered_obj + objArrayOopDesc::obj_at_offset<oop>(i));
726         relocate_field_in_buffer<oop>(addr, heap_info->oopmap());
727       }
728     }
729   }
730 
731   compute_ptrmap(heap_info);
732 
733   size_t total_bytes = (size_t)_buffer->length();
734   log_bitmap_usage("oopmap", heap_info->oopmap(), total_bytes / (UseCompressedOops ? sizeof(narrowOop) : sizeof(oop)));
735   log_bitmap_usage("ptrmap", heap_info->ptrmap(), total_bytes / sizeof(address));
736 }
737 
738 void ArchiveHeapWriter::mark_native_pointer(oop src_obj, int field_offset) {
739   Metadata* ptr = src_obj->metadata_field_acquire(field_offset);
740   if (ptr != nullptr) {
741     NativePointerInfo info;
742     info._src_obj = src_obj;
743     info._field_offset = field_offset;
744     _native_pointers->append(info);
745     HeapShared::set_has_native_pointers(src_obj);
746     _num_native_ptrs ++;
747   }
748 }
749 
750 void ArchiveHeapWriter::compute_ptrmap(ArchiveHeapInfo* heap_info) {
751   int num_non_null_ptrs = 0;
752   Metadata** bottom = (Metadata**) _requested_bottom;
753   Metadata** top = (Metadata**) _requested_top; // exclusive
754   heap_info->ptrmap()->resize(top - bottom);
755 
756   BitMap::idx_t max_idx = 32; // paranoid - don't make it too small
757   for (int i = 0; i < _native_pointers->length(); i++) {
758     NativePointerInfo info = _native_pointers->at(i);
759     oop src_obj = info._src_obj;
760     int field_offset = info._field_offset;
761     HeapShared::CachedOopInfo* p = HeapShared::archived_object_cache()->get(src_obj);
762     // requested_field_addr = the address of this field in the requested space
763     oop requested_obj = requested_obj_from_buffer_offset(p->buffer_offset());
764     Metadata** requested_field_addr = (Metadata**)(cast_from_oop<address>(requested_obj) + field_offset);
765     assert(bottom <= requested_field_addr && requested_field_addr < top, "range check");
766 
767     // Mark this field in the bitmap
768     BitMap::idx_t idx = requested_field_addr - bottom;
769     heap_info->ptrmap()->set_bit(idx);
770     num_non_null_ptrs ++;
771     max_idx = MAX2(max_idx, idx);
772 
773     // Set the native pointer to the requested address of the metadata (at runtime, the metadata will have
774     // this address if the RO/RW regions are mapped at the default location).
775 
776     Metadata** buffered_field_addr = requested_addr_to_buffered_addr(requested_field_addr);
777     Metadata* native_ptr = *buffered_field_addr;
778     guarantee(native_ptr != nullptr, "sanity");
779 
780     if (RegeneratedClasses::has_been_regenerated(native_ptr)) {
781       native_ptr = RegeneratedClasses::get_regenerated_object(native_ptr);
782     }
783 
784     guarantee(ArchiveBuilder::current()->has_been_archived((address)native_ptr),
785               "Metadata %p should have been archived", native_ptr);
786 
787     address buffered_native_ptr = ArchiveBuilder::current()->get_buffered_addr((address)native_ptr);
788     address requested_native_ptr = ArchiveBuilder::current()->to_requested(buffered_native_ptr);
789     *buffered_field_addr = (Metadata*)requested_native_ptr;
790   }
791 
792   heap_info->ptrmap()->resize(max_idx + 1);
793   log_info(aot, heap)("calculate_ptrmap: marked %d non-null native pointers for heap region (%zu bits)",
794                       num_non_null_ptrs, size_t(heap_info->ptrmap()->size()));
795 }
796 
797 #endif // INCLUDE_CDS_JAVA_HEAP