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