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