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 static size_t _num_strings = 0;
 66 static size_t _string_bytes = 0; 
 67 static size_t _num_packages = 0;
 68 static size_t _num_protection_domains = 0;
 69 
 70 GrowableArrayCHeap<ArchiveHeapWriter::NativePointerInfo, mtClassShared>* ArchiveHeapWriter::_native_pointers;
 71 GrowableArrayCHeap<oop, mtClassShared>* ArchiveHeapWriter::_source_objs;
 72 GrowableArrayCHeap<ArchiveHeapWriter::HeapObjOrder, mtClassShared>* ArchiveHeapWriter::_source_objs_order;
 73 
 74 ArchiveHeapWriter::BufferOffsetToSourceObjectTable*
 75   ArchiveHeapWriter::_buffer_offset_to_source_obj_table = nullptr;
 76 
 77 
 78 typedef HashTable<
 79       size_t,    // offset of a filler from ArchiveHeapWriter::buffer_bottom()
 80       size_t,    // size of this filler (in bytes)
 81       127,       // prime number
 82       AnyObj::C_HEAP,
 83       mtClassShared> FillersTable;
 84 static FillersTable* _fillers;
 85 static int _num_native_ptrs = 0;
 86 
 87 void ArchiveHeapWriter::init() {
 88   if (CDSConfig::is_dumping_heap()) {
 89     Universe::heap()->collect(GCCause::_java_lang_system_gc);
 90 
 91     _buffer_offset_to_source_obj_table = new BufferOffsetToSourceObjectTable(/*size (prime)*/36137, /*max size*/1 * M);
 92     _fillers = new FillersTable();
 93     _requested_bottom = nullptr;
 94     _requested_top = nullptr;
 95 
 96     _native_pointers = new GrowableArrayCHeap<NativePointerInfo, mtClassShared>(2048);
 97     _source_objs = new GrowableArrayCHeap<oop, mtClassShared>(10000);
 98 
 99     guarantee(MIN_GC_REGION_ALIGNMENT <= G1HeapRegion::min_region_size_in_words() * HeapWordSize, "must be");
100   }
101 }
102 
103 void ArchiveHeapWriter::delete_tables_with_raw_oops() {
104   delete _source_objs;
105   _source_objs = nullptr;
106 }
107 
108 void ArchiveHeapWriter::add_source_obj(oop src_obj) {
109   _source_objs->append(src_obj);
110 }
111 
112 void ArchiveHeapWriter::write(GrowableArrayCHeap<oop, mtClassShared>* roots,
113                               ArchiveHeapInfo* heap_info) {
114   assert(CDSConfig::is_dumping_heap(), "sanity");
115   allocate_buffer();
116   copy_source_objs_to_buffer(roots);
117   set_requested_address(heap_info);
118   relocate_embedded_oops(roots, heap_info);
119 }
120 
121 bool ArchiveHeapWriter::is_too_large_to_archive(oop o) {
122   return is_too_large_to_archive(o->size());
123 }
124 
125 bool ArchiveHeapWriter::is_string_too_large_to_archive(oop string) {
126   typeArrayOop value = java_lang_String::value_no_keepalive(string);
127   return is_too_large_to_archive(value);
128 }
129 
130 bool ArchiveHeapWriter::is_too_large_to_archive(size_t size) {
131   assert(size > 0, "no zero-size object");
132   assert(size * HeapWordSize > size, "no overflow");
133   static_assert(MIN_GC_REGION_ALIGNMENT > 0, "must be positive");
134 
135   size_t byte_size = size * HeapWordSize;
136   if (byte_size > size_t(MIN_GC_REGION_ALIGNMENT)) {
137     return true;
138   } else {
139     return false;
140   }
141 }
142 
143 // Various lookup functions between source_obj, buffered_obj and requested_obj
144 bool ArchiveHeapWriter::is_in_requested_range(oop o) {
145   assert(_requested_bottom != nullptr, "do not call before _requested_bottom is initialized");
146   address a = cast_from_oop<address>(o);
147   return (_requested_bottom <= a && a < _requested_top);
148 }
149 
150 oop ArchiveHeapWriter::requested_obj_from_buffer_offset(size_t offset) {
151   oop req_obj = cast_to_oop(_requested_bottom + offset);
152   assert(is_in_requested_range(req_obj), "must be");
153   return req_obj;
154 }
155 
156 oop ArchiveHeapWriter::source_obj_to_requested_obj(oop src_obj) {
157   assert(CDSConfig::is_dumping_heap(), "dump-time only");
158   HeapShared::CachedOopInfo* p = HeapShared::get_cached_oop_info(src_obj);
159   if (p != nullptr) {
160     return requested_obj_from_buffer_offset(p->buffer_offset());
161   } else {
162     return nullptr;
163   }
164 }
165 
166 oop ArchiveHeapWriter::buffered_addr_to_source_obj(address buffered_addr) {
167   OopHandle* oh = _buffer_offset_to_source_obj_table->get(buffered_address_to_offset(buffered_addr));
168   if (oh != nullptr) {
169     return oh->resolve();
170   } else {
171     return nullptr;
172   }
173 }
174 
175 Klass* ArchiveHeapWriter::real_klass_of_buffered_oop(address buffered_addr) {
176   oop p = buffered_addr_to_source_obj(buffered_addr);
177   if (p != nullptr) {
178     return p->klass();
179   } else if (get_filler_size_at(buffered_addr) > 0) {
180     return Universe::fillerArrayKlass();
181   } else {
182     // This is one of the root segments
183     return Universe::objectArrayKlass();
184   }
185 }
186 
187 size_t ArchiveHeapWriter::size_of_buffered_oop(address buffered_addr) {
188   oop p = buffered_addr_to_source_obj(buffered_addr);
189   if (p != nullptr) {
190     return p->size();
191   }
192 
193   size_t nbytes = get_filler_size_at(buffered_addr);
194   if (nbytes > 0) {
195     assert((nbytes % BytesPerWord) == 0, "should be aligned");
196     return nbytes / BytesPerWord;
197   }
198 
199   address hrs = buffer_bottom();
200   for (size_t seg_idx = 0; seg_idx < _heap_root_segments.count(); seg_idx++) {
201     nbytes = _heap_root_segments.size_in_bytes(seg_idx);
202     if (hrs == buffered_addr) {
203       assert((nbytes % BytesPerWord) == 0, "should be aligned");
204       return nbytes / BytesPerWord;
205     }
206     hrs += nbytes;
207   }
208 
209   ShouldNotReachHere();
210   return 0;
211 }
212 
213 address ArchiveHeapWriter::buffered_addr_to_requested_addr(address buffered_addr) {
214   return _requested_bottom + buffered_address_to_offset(buffered_addr);
215 }
216 
217 address ArchiveHeapWriter::requested_address() {
218   assert(_buffer != nullptr, "must be initialized");
219   return _requested_bottom;
220 }
221 
222 void ArchiveHeapWriter::allocate_buffer() {
223   int initial_buffer_size = 100000;
224   _buffer = new GrowableArrayCHeap<u1, mtClassShared>(initial_buffer_size);
225   _buffer_used = 0;
226   ensure_buffer_space(1); // so that buffer_bottom() works
227 }
228 
229 void ArchiveHeapWriter::ensure_buffer_space(size_t min_bytes) {
230   // We usually have very small heaps. If we get a huge one it's probably caused by a bug.
231   guarantee(min_bytes <= max_jint, "we dont support archiving more than 2G of objects");
232   _buffer->at_grow(to_array_index(min_bytes));
233 }
234 
235 objArrayOop ArchiveHeapWriter::allocate_root_segment(size_t offset, int element_count) {
236   HeapWord* mem = offset_to_buffered_address<HeapWord *>(offset);
237   memset(mem, 0, objArrayOopDesc::object_size(element_count));
238 
239   // The initialization code is copied from MemAllocator::finish and ObjArrayAllocator::initialize.
240   if (UseCompactObjectHeaders) {
241     oopDesc::release_set_mark(mem, Universe::objectArrayKlass()->prototype_header());
242   } else {
243     oopDesc::set_mark(mem, markWord::prototype());
244     oopDesc::release_set_klass(mem, Universe::objectArrayKlass());
245   }
246   arrayOopDesc::set_length(mem, element_count);
247   return objArrayOop(cast_to_oop(mem));
248 }
249 
250 void ArchiveHeapWriter::root_segment_at_put(objArrayOop segment, int index, oop root) {
251   // Do not use arrayOop->obj_at_put(i, o) as arrayOop is outside the real heap!
252   if (UseCompressedOops) {
253     *segment->obj_at_addr<narrowOop>(index) = CompressedOops::encode(root);
254   } else {
255     *segment->obj_at_addr<oop>(index) = root;
256   }
257 }
258 
259 void ArchiveHeapWriter::copy_roots_to_buffer(GrowableArrayCHeap<oop, mtClassShared>* roots) {
260   // Depending on the number of classes we are archiving, a single roots array may be
261   // larger than MIN_GC_REGION_ALIGNMENT. Roots are allocated first in the buffer, which
262   // allows us to chop the large array into a series of "segments". Current layout
263   // starts with zero or more segments exactly fitting MIN_GC_REGION_ALIGNMENT, and end
264   // with a single segment that may be smaller than MIN_GC_REGION_ALIGNMENT.
265   // This is simple and efficient. We do not need filler objects anywhere between the segments,
266   // or immediately after the last segment. This allows starting the object dump immediately
267   // after the roots.
268 
269   assert((_buffer_used % MIN_GC_REGION_ALIGNMENT) == 0,
270          "Pre-condition: Roots start at aligned boundary: %zu", _buffer_used);
271 
272   int max_elem_count = ((MIN_GC_REGION_ALIGNMENT - arrayOopDesc::header_size_in_bytes()) / heapOopSize);
273   assert(objArrayOopDesc::object_size(max_elem_count)*HeapWordSize == MIN_GC_REGION_ALIGNMENT,
274          "Should match exactly");
275 
276   HeapRootSegments segments(_buffer_used,
277                             roots->length(),
278                             MIN_GC_REGION_ALIGNMENT,
279                             max_elem_count);
280 
281   int root_index = 0;
282   for (size_t seg_idx = 0; seg_idx < segments.count(); seg_idx++) {
283     int size_elems = segments.size_in_elems(seg_idx);
284     size_t size_bytes = segments.size_in_bytes(seg_idx);
285 
286     size_t oop_offset = _buffer_used;
287     _buffer_used = oop_offset + size_bytes;
288     ensure_buffer_space(_buffer_used);
289 
290     assert((oop_offset % MIN_GC_REGION_ALIGNMENT) == 0,
291            "Roots segment %zu start is not aligned: %zu",
292            segments.count(), oop_offset);
293 
294     objArrayOop seg_oop = allocate_root_segment(oop_offset, size_elems);
295     for (int i = 0; i < size_elems; i++) {
296       root_segment_at_put(seg_oop, i, roots->at(root_index++));
297     }
298 
299     log_info(aot, heap)("archived obj root segment [%d] = %zu bytes, obj = " PTR_FORMAT,
300                         size_elems, size_bytes, p2i(seg_oop));
301   }
302 
303   assert(root_index == roots->length(), "Post-condition: All roots are handled");
304 
305   _heap_root_segments = segments;
306 }
307 
308 // The goal is to sort the objects in increasing order of:
309 // - objects that have only oop pointers
310 // - objects that have both native and oop pointers
311 // - objects that have only native pointers
312 // - objects that have no pointers
313 static int oop_sorting_rank(oop o) {
314   bool has_oop_ptr, has_native_ptr;
315   HeapShared::get_pointer_info(o, has_oop_ptr, has_native_ptr);
316 
317   if (has_oop_ptr) {
318     if (!has_native_ptr) {
319       return 0;
320     } else {
321       return 1;
322     }
323   } else {
324     if (has_native_ptr) {
325       return 2;
326     } else {
327       return 3;
328     }
329   }
330 }
331 
332 int ArchiveHeapWriter::compare_objs_by_oop_fields(HeapObjOrder* a, HeapObjOrder* b) {
333   int rank_a = a->_rank;
334   int rank_b = b->_rank;
335 
336   if (rank_a != rank_b) {
337     return rank_a - rank_b;
338   } else {
339     // If they are the same rank, sort them by their position in the _source_objs array
340     return a->_index - b->_index;
341   }
342 }
343 
344 void ArchiveHeapWriter::sort_source_objs() {
345   log_info(aot)("sorting heap objects");
346   int len = _source_objs->length();
347   _source_objs_order = new GrowableArrayCHeap<HeapObjOrder, mtClassShared>(len);
348 
349   for (int i = 0; i < len; i++) {
350     oop o = _source_objs->at(i);
351     int rank = oop_sorting_rank(o);
352     HeapObjOrder os = {i, rank};
353     _source_objs_order->append(os);
354   }
355   log_info(aot)("computed ranks");
356   _source_objs_order->sort(compare_objs_by_oop_fields);
357   log_info(aot)("sorting heap objects done");
358 }
359 
360 void ArchiveHeapWriter::copy_source_objs_to_buffer(GrowableArrayCHeap<oop, mtClassShared>* roots) {
361   // There could be multiple root segments, which we want to be aligned by region.
362   // Putting them ahead of objects makes sure we waste no space.
363   copy_roots_to_buffer(roots);
364 
365   sort_source_objs();
366   for (int i = 0; i < _source_objs_order->length(); i++) {
367     int src_obj_index = _source_objs_order->at(i)._index;
368     oop src_obj = _source_objs->at(src_obj_index);
369     HeapShared::CachedOopInfo* info = HeapShared::get_cached_oop_info(src_obj);
370     assert(info != nullptr, "must be");
371     size_t buffer_offset = copy_one_source_obj_to_buffer(src_obj);
372     info->set_buffer_offset(buffer_offset);
373     assert(buffer_offset <= 0x7fffffff, "sanity");
374     HeapShared::add_to_permanent_oop_table(src_obj, (int)buffer_offset);
375 
376     OopHandle handle(Universe::vm_global(), src_obj);
377     _buffer_offset_to_source_obj_table->put_when_absent(buffer_offset, handle);
378     _buffer_offset_to_source_obj_table->maybe_grow();
379 
380     if (java_lang_Module::is_instance(src_obj)) {
381       Modules::check_archived_module_oop(src_obj);
382     }
383   }
384 
385   log_info(aot)("Size of heap region = %zu bytes, %d objects, %d roots, %d native ptrs",
386                 _buffer_used, _source_objs->length() + 1, roots->length(), _num_native_ptrs);
387   log_info(cds)("   strings            = %8zu (%zu bytes)", _num_strings, _string_bytes);
388   log_info(cds)("   packages           = %8zu", _num_packages);
389   log_info(cds)("   protection domains = %8zu", _num_protection_domains);
390 }
391 
392 size_t ArchiveHeapWriter::filler_array_byte_size(int length) {
393   size_t byte_size = objArrayOopDesc::object_size(length) * HeapWordSize;
394   return byte_size;
395 }
396 
397 int ArchiveHeapWriter::filler_array_length(size_t fill_bytes) {
398   assert(is_object_aligned(fill_bytes), "must be");
399   size_t elemSize = (UseCompressedOops ? sizeof(narrowOop) : sizeof(oop));
400 
401   int initial_length = to_array_length(fill_bytes / elemSize);
402   for (int length = initial_length; length >= 0; length --) {
403     size_t array_byte_size = filler_array_byte_size(length);
404     if (array_byte_size == fill_bytes) {
405       return length;
406     }
407   }
408 
409   ShouldNotReachHere();
410   return -1;
411 }
412 
413 HeapWord* ArchiveHeapWriter::init_filler_array_at_buffer_top(int array_length, size_t fill_bytes) {
414   assert(UseCompressedClassPointers, "Archived heap only supported for compressed klasses");
415   Klass* oak = Universe::objectArrayKlass(); // already relocated to point to archived klass
416   HeapWord* mem = offset_to_buffered_address<HeapWord*>(_buffer_used);
417   memset(mem, 0, fill_bytes);
418   narrowKlass nk = ArchiveBuilder::current()->get_requested_narrow_klass(oak);
419   if (UseCompactObjectHeaders) {
420     oopDesc::release_set_mark(mem, markWord::prototype().set_narrow_klass(nk));
421   } else {
422     oopDesc::set_mark(mem, markWord::prototype());
423     cast_to_oop(mem)->set_narrow_klass(nk);
424   }
425   arrayOopDesc::set_length(mem, array_length);
426   return mem;
427 }
428 
429 void ArchiveHeapWriter::maybe_fill_gc_region_gap(size_t required_byte_size) {
430   // We fill only with arrays (so we don't need to use a single HeapWord filler if the
431   // leftover space is smaller than a zero-sized array object). Therefore, we need to
432   // make sure there's enough space of min_filler_byte_size in the current region after
433   // required_byte_size has been allocated. If not, fill the remainder of the current
434   // region.
435   size_t min_filler_byte_size = filler_array_byte_size(0);
436   size_t new_used = _buffer_used + required_byte_size + min_filler_byte_size;
437 
438   const size_t cur_min_region_bottom = align_down(_buffer_used, MIN_GC_REGION_ALIGNMENT);
439   const size_t next_min_region_bottom = align_down(new_used, MIN_GC_REGION_ALIGNMENT);
440 
441   if (cur_min_region_bottom != next_min_region_bottom) {
442     // Make sure that no objects span across MIN_GC_REGION_ALIGNMENT. This way
443     // we can map the region in any region-based collector.
444     assert(next_min_region_bottom > cur_min_region_bottom, "must be");
445     assert(next_min_region_bottom - cur_min_region_bottom == MIN_GC_REGION_ALIGNMENT,
446            "no buffered object can be larger than %d bytes",  MIN_GC_REGION_ALIGNMENT);
447 
448     const size_t filler_end = next_min_region_bottom;
449     const size_t fill_bytes = filler_end - _buffer_used;
450     assert(fill_bytes > 0, "must be");
451     ensure_buffer_space(filler_end);
452 
453     int array_length = filler_array_length(fill_bytes);
454     log_info(aot, heap)("Inserting filler obj array of %d elements (%zu bytes total) @ buffer offset %zu",
455                         array_length, fill_bytes, _buffer_used);
456     HeapWord* filler = init_filler_array_at_buffer_top(array_length, fill_bytes);
457     _buffer_used = filler_end;
458     _fillers->put(buffered_address_to_offset((address)filler), fill_bytes);
459   }
460 }
461 
462 size_t ArchiveHeapWriter::get_filler_size_at(address buffered_addr) {
463   size_t* p = _fillers->get(buffered_address_to_offset(buffered_addr));
464   if (p != nullptr) {
465     assert(*p > 0, "filler must be larger than zero bytes");
466     return *p;
467   } else {
468     return 0; // buffered_addr is not a filler
469   }
470 }
471 
472 template <typename T>
473 void update_buffered_object_field(address buffered_obj, int field_offset, T value) {
474   T* field_addr = cast_to_oop(buffered_obj)->field_addr<T>(field_offset);
475   *field_addr = value;
476 }
477 
478 void ArchiveHeapWriter::update_stats(oop src_obj) {
479   if (java_lang_String::is_instance(src_obj)) {
480     _num_strings ++;
481     _string_bytes += src_obj->size() * HeapWordSize;
482     _string_bytes += java_lang_String::value(src_obj)->size() * HeapWordSize;
483   } else {
484     Klass* k = src_obj->klass();
485     Symbol* name = k->name();
486     if (name->equals("java/lang/NamedPackage") || name->equals("java/lang/Package")) {
487       _num_packages ++;
488     } else if (name->equals("java/security/ProtectionDomain")) {
489       _num_protection_domains ++;
490     }
491   }
492 }
493 
494 size_t ArchiveHeapWriter::copy_one_source_obj_to_buffer(oop src_obj) {
495   update_stats(src_obj);
496 
497   assert(!is_too_large_to_archive(src_obj), "already checked");
498   size_t byte_size = src_obj->size() * HeapWordSize;
499   assert(byte_size > 0, "no zero-size objects");
500 
501   // For region-based collectors such as G1, the archive heap may be mapped into
502   // multiple regions. We need to make sure that we don't have an object that can possible
503   // span across two regions.
504   maybe_fill_gc_region_gap(byte_size);
505 
506   size_t new_used = _buffer_used + byte_size;
507   assert(new_used > _buffer_used, "no wrap around");
508 
509   size_t cur_min_region_bottom = align_down(_buffer_used, MIN_GC_REGION_ALIGNMENT);
510   size_t next_min_region_bottom = align_down(new_used, MIN_GC_REGION_ALIGNMENT);
511   assert(cur_min_region_bottom == next_min_region_bottom, "no object should cross minimal GC region boundaries");
512 
513   ensure_buffer_space(new_used);
514 
515   address from = cast_from_oop<address>(src_obj);
516   address to = offset_to_buffered_address<address>(_buffer_used);
517   assert(is_object_aligned(_buffer_used), "sanity");
518   assert(is_object_aligned(byte_size), "sanity");
519   memcpy(to, from, byte_size);
520 
521   // These native pointers will be restored explicitly at run time.
522   if (java_lang_Module::is_instance(src_obj)) {
523     update_buffered_object_field<ModuleEntry*>(to, java_lang_Module::module_entry_offset(), nullptr);
524   } else if (java_lang_ClassLoader::is_instance(src_obj)) {
525 #ifdef ASSERT
526     // We only archive these loaders
527     if (src_obj != SystemDictionary::java_platform_loader() &&
528         src_obj != SystemDictionary::java_system_loader()) {
529       assert(src_obj->klass()->name()->equals("jdk/internal/loader/ClassLoaders$BootClassLoader"), "must be");
530     }
531 #endif
532     update_buffered_object_field<ClassLoaderData*>(to, java_lang_ClassLoader::loader_data_offset(), nullptr);
533   }
534 
535   size_t buffered_obj_offset = _buffer_used;
536   _buffer_used = new_used;
537 
538   return buffered_obj_offset;
539 }
540 
541 void ArchiveHeapWriter::set_requested_address(ArchiveHeapInfo* info) {
542   assert(!info->is_used(), "only set once");
543 
544   size_t heap_region_byte_size = _buffer_used;
545   assert(heap_region_byte_size > 0, "must archived at least one object!");
546 
547   if (UseCompressedOops) {
548     if (UseG1GC) {
549       address heap_end = (address)G1CollectedHeap::heap()->reserved().end();
550       log_info(aot, heap)("Heap end = %p", heap_end);
551       _requested_bottom = align_down(heap_end - heap_region_byte_size, G1HeapRegion::GrainBytes);
552       _requested_bottom = align_down(_requested_bottom, MIN_GC_REGION_ALIGNMENT);
553       assert(is_aligned(_requested_bottom, G1HeapRegion::GrainBytes), "sanity");
554     } else {
555       _requested_bottom = align_up(CompressedOops::begin(), MIN_GC_REGION_ALIGNMENT);
556     }
557   } else {
558     // We always write the objects as if the heap started at this address. This
559     // makes the contents of the archive heap deterministic.
560     //
561     // Note that at runtime, the heap address is selected by the OS, so the archive
562     // heap will not be mapped at 0x10000000, and the contents need to be patched.
563     _requested_bottom = align_up((address)NOCOOPS_REQUESTED_BASE, MIN_GC_REGION_ALIGNMENT);
564   }
565 
566   assert(is_aligned(_requested_bottom, MIN_GC_REGION_ALIGNMENT), "sanity");
567 
568   _requested_top = _requested_bottom + _buffer_used;
569 
570   info->set_buffer_region(MemRegion(offset_to_buffered_address<HeapWord*>(0),
571                                     offset_to_buffered_address<HeapWord*>(_buffer_used)));
572   info->set_heap_root_segments(_heap_root_segments);
573 }
574 
575 // Oop relocation
576 
577 template <typename T> T* ArchiveHeapWriter::requested_addr_to_buffered_addr(T* p) {
578   assert(is_in_requested_range(cast_to_oop(p)), "must be");
579 
580   address addr = address(p);
581   assert(addr >= _requested_bottom, "must be");
582   size_t offset = addr - _requested_bottom;
583   return offset_to_buffered_address<T*>(offset);
584 }
585 
586 template <typename T> oop ArchiveHeapWriter::load_source_oop_from_buffer(T* buffered_addr) {
587   oop o = load_oop_from_buffer(buffered_addr);
588   assert(!in_buffer(cast_from_oop<address>(o)), "must point to source oop");
589   return o;
590 }
591 
592 template <typename T> void ArchiveHeapWriter::store_requested_oop_in_buffer(T* buffered_addr,
593                                                                             oop request_oop) {
594   assert(is_in_requested_range(request_oop), "must be");
595   store_oop_in_buffer(buffered_addr, request_oop);
596 }
597 
598 inline void ArchiveHeapWriter::store_oop_in_buffer(oop* buffered_addr, oop requested_obj) {
599   *buffered_addr = requested_obj;
600 }
601 
602 inline void ArchiveHeapWriter::store_oop_in_buffer(narrowOop* buffered_addr, oop requested_obj) {
603   narrowOop val = CompressedOops::encode_not_null(requested_obj);
604   *buffered_addr = val;
605 }
606 
607 oop ArchiveHeapWriter::load_oop_from_buffer(oop* buffered_addr) {
608   return *buffered_addr;
609 }
610 
611 oop ArchiveHeapWriter::load_oop_from_buffer(narrowOop* buffered_addr) {
612   return CompressedOops::decode(*buffered_addr);
613 }
614 
615 template <typename T> void ArchiveHeapWriter::relocate_field_in_buffer(T* field_addr_in_buffer, CHeapBitMap* oopmap) {
616   oop source_referent = load_source_oop_from_buffer<T>(field_addr_in_buffer);
617   if (source_referent != nullptr) {
618     if (java_lang_Class::is_instance(source_referent)) {
619       Klass* k = java_lang_Class::as_Klass(source_referent);
620       if (RegeneratedClasses::has_been_regenerated(k)) {
621         source_referent = RegeneratedClasses::get_regenerated_object(k)->java_mirror();
622       }
623       // When the source object points to a "real" mirror, the buffered object should point
624       // to the "scratch" mirror, which has all unarchivable fields scrubbed (to be reinstated
625       // at run time).
626       source_referent = HeapShared::scratch_java_mirror(source_referent);
627       assert(source_referent != nullptr, "must be");
628     }
629     oop request_referent = source_obj_to_requested_obj(source_referent);
630     store_requested_oop_in_buffer<T>(field_addr_in_buffer, request_referent);
631     mark_oop_pointer<T>(field_addr_in_buffer, oopmap);
632   }
633 }
634 
635 template <typename T> void ArchiveHeapWriter::mark_oop_pointer(T* buffered_addr, CHeapBitMap* oopmap) {
636   T* request_p = (T*)(buffered_addr_to_requested_addr((address)buffered_addr));
637   address requested_region_bottom;
638 
639   assert(request_p >= (T*)_requested_bottom, "sanity");
640   assert(request_p <  (T*)_requested_top, "sanity");
641   requested_region_bottom = _requested_bottom;
642 
643   // Mark the pointer in the oopmap
644   T* region_bottom = (T*)requested_region_bottom;
645   assert(request_p >= region_bottom, "must be");
646   BitMap::idx_t idx = request_p - region_bottom;
647   assert(idx < oopmap->size(), "overflow");
648   oopmap->set_bit(idx);
649 }
650 
651 void ArchiveHeapWriter::update_header_for_requested_obj(oop requested_obj, oop src_obj,  Klass* src_klass) {
652   assert(UseCompressedClassPointers, "Archived heap only supported for compressed klasses");
653   narrowKlass nk = ArchiveBuilder::current()->get_requested_narrow_klass(src_klass);
654   address buffered_addr = requested_addr_to_buffered_addr(cast_from_oop<address>(requested_obj));
655 
656   oop fake_oop = cast_to_oop(buffered_addr);
657   if (UseCompactObjectHeaders) {
658     fake_oop->set_mark(markWord::prototype().set_narrow_klass(nk));
659   } else {
660     fake_oop->set_narrow_klass(nk);
661   }
662 
663   if (src_obj == nullptr) {
664     return;
665   }
666   // We need to retain the identity_hash, because it may have been used by some hashtables
667   // in the shared heap.
668   if (!src_obj->fast_no_hash_check()) {
669     intptr_t src_hash = src_obj->identity_hash();
670     if (UseCompactObjectHeaders) {
671       fake_oop->set_mark(markWord::prototype().set_narrow_klass(nk).copy_set_hash(src_hash));
672     } else {
673       fake_oop->set_mark(markWord::prototype().copy_set_hash(src_hash));
674     }
675     assert(fake_oop->mark().is_unlocked(), "sanity");
676 
677     DEBUG_ONLY(intptr_t archived_hash = fake_oop->identity_hash());
678     assert(src_hash == archived_hash, "Different hash codes: original " INTPTR_FORMAT ", archived " INTPTR_FORMAT, src_hash, archived_hash);
679   }
680   // Strip age bits.
681   fake_oop->set_mark(fake_oop->mark().set_age(0));
682 }
683 
684 class ArchiveHeapWriter::EmbeddedOopRelocator: public BasicOopIterateClosure {
685   oop _src_obj;
686   address _buffered_obj;
687   CHeapBitMap* _oopmap;
688   bool _is_java_lang_ref;
689 public:
690   EmbeddedOopRelocator(oop src_obj, address buffered_obj, CHeapBitMap* oopmap) :
691     _src_obj(src_obj), _buffered_obj(buffered_obj), _oopmap(oopmap)
692   {
693     _is_java_lang_ref = AOTReferenceObjSupport::check_if_ref_obj(src_obj);
694   }
695 
696   void do_oop(narrowOop *p) { EmbeddedOopRelocator::do_oop_work(p); }
697   void do_oop(      oop *p) { EmbeddedOopRelocator::do_oop_work(p); }
698 
699 private:
700   template <class T> void do_oop_work(T *p) {
701     int field_offset = pointer_delta_as_int((char*)p, cast_from_oop<char*>(_src_obj));
702     T* field_addr = (T*)(_buffered_obj + field_offset);
703     if (_is_java_lang_ref && AOTReferenceObjSupport::skip_field(field_offset)) {
704       // Do not copy these fields. Set them to null
705       *field_addr = (T)0x0;
706     } else {
707       ArchiveHeapWriter::relocate_field_in_buffer<T>(field_addr, _oopmap);
708     }
709   }
710 };
711 
712 static void log_bitmap_usage(const char* which, BitMap* bitmap, size_t total_bits) {
713   // The whole heap is covered by total_bits, but there are only non-zero bits within [start ... end).
714   size_t start = bitmap->find_first_set_bit(0);
715   size_t end = bitmap->size();
716   log_info(aot)("%s = %7zu ... %7zu (%3zu%% ... %3zu%% = %3zu%%)", which,
717                 start, end,
718                 start * 100 / total_bits,
719                 end * 100 / total_bits,
720                 (end - start) * 100 / total_bits);
721 }
722 
723 // Update all oop fields embedded in the buffered objects
724 void ArchiveHeapWriter::relocate_embedded_oops(GrowableArrayCHeap<oop, mtClassShared>* roots,
725                                                ArchiveHeapInfo* heap_info) {
726   size_t oopmap_unit = (UseCompressedOops ? sizeof(narrowOop) : sizeof(oop));
727   size_t heap_region_byte_size = _buffer_used;
728   heap_info->oopmap()->resize(heap_region_byte_size   / oopmap_unit);
729 
730   for (int i = 0; i < _source_objs_order->length(); i++) {
731     int src_obj_index = _source_objs_order->at(i)._index;
732     oop src_obj = _source_objs->at(src_obj_index);
733     HeapShared::CachedOopInfo* info = HeapShared::get_cached_oop_info(src_obj);
734     assert(info != nullptr, "must be");
735     oop requested_obj = requested_obj_from_buffer_offset(info->buffer_offset());
736     update_header_for_requested_obj(requested_obj, src_obj, src_obj->klass());
737     address buffered_obj = offset_to_buffered_address<address>(info->buffer_offset());
738     EmbeddedOopRelocator relocator(src_obj, buffered_obj, heap_info->oopmap());
739     src_obj->oop_iterate(&relocator);
740   };
741 
742   // Relocate HeapShared::roots(), which is created in copy_roots_to_buffer() and
743   // doesn't have a corresponding src_obj, so we can't use EmbeddedOopRelocator on it.
744   for (size_t seg_idx = 0; seg_idx < _heap_root_segments.count(); seg_idx++) {
745     size_t seg_offset = _heap_root_segments.segment_offset(seg_idx);
746 
747     objArrayOop requested_obj = (objArrayOop)requested_obj_from_buffer_offset(seg_offset);
748     update_header_for_requested_obj(requested_obj, nullptr, Universe::objectArrayKlass());
749     address buffered_obj = offset_to_buffered_address<address>(seg_offset);
750     int length = _heap_root_segments.size_in_elems(seg_idx);
751 
752     if (UseCompressedOops) {
753       for (int i = 0; i < length; i++) {
754         narrowOop* addr = (narrowOop*)(buffered_obj + objArrayOopDesc::obj_at_offset<narrowOop>(i));
755         relocate_field_in_buffer<narrowOop>(addr, heap_info->oopmap());
756       }
757     } else {
758       for (int i = 0; i < length; i++) {
759         oop* addr = (oop*)(buffered_obj + objArrayOopDesc::obj_at_offset<oop>(i));
760         relocate_field_in_buffer<oop>(addr, heap_info->oopmap());
761       }
762     }
763   }
764 
765   compute_ptrmap(heap_info);
766 
767   size_t total_bytes = (size_t)_buffer->length();
768   log_bitmap_usage("oopmap", heap_info->oopmap(), total_bytes / (UseCompressedOops ? sizeof(narrowOop) : sizeof(oop)));
769   log_bitmap_usage("ptrmap", heap_info->ptrmap(), total_bytes / sizeof(address));
770 }
771 
772 void ArchiveHeapWriter::mark_native_pointer(oop src_obj, int field_offset) {
773   Metadata* ptr = src_obj->metadata_field_acquire(field_offset);
774   if (ptr != nullptr) {
775     NativePointerInfo info;
776     info._src_obj = src_obj;
777     info._field_offset = field_offset;
778     _native_pointers->append(info);
779     HeapShared::set_has_native_pointers(src_obj);
780     _num_native_ptrs ++;
781   }
782 }
783 
784 // Do we have a jlong/jint field that's actually a pointer to a MetaspaceObj?
785 bool ArchiveHeapWriter::is_marked_as_native_pointer(ArchiveHeapInfo* heap_info, address buffered_obj, int field_offset) {
786   size_t offset = buffered_address_to_offset(buffered_obj) + checked_cast<size_t>(field_offset); // in bytes
787   BitMap::idx_t idx = checked_cast<BitMap::idx_t>(offset) / HeapWordSize;
788   // Leading zeros have been removed so some addresses may not be in the ptrmap
789   size_t start_pos = FileMapInfo::current_info()->heap_ptrmap_start_pos();
790   if (idx < start_pos) {
791     return false;
792   } else {
793     idx -= start_pos;
794   }
795   return (idx < heap_info->ptrmap()->size()) && (heap_info->ptrmap()->at(idx) == true);
796 }
797 
798 void ArchiveHeapWriter::compute_ptrmap(ArchiveHeapInfo* heap_info) {
799   int num_non_null_ptrs = 0;
800   Metadata** bottom = (Metadata**) _requested_bottom;
801   Metadata** top = (Metadata**) _requested_top; // exclusive
802   heap_info->ptrmap()->resize(top - bottom);
803 
804   BitMap::idx_t max_idx = 32; // paranoid - don't make it too small
805   for (int i = 0; i < _native_pointers->length(); i++) {
806     NativePointerInfo info = _native_pointers->at(i);
807     oop src_obj = info._src_obj;
808     int field_offset = info._field_offset;
809     HeapShared::CachedOopInfo* p = HeapShared::get_cached_oop_info(src_obj);
810     // requested_field_addr = the address of this field in the requested space
811     oop requested_obj = requested_obj_from_buffer_offset(p->buffer_offset());
812     Metadata** requested_field_addr = (Metadata**)(cast_from_oop<address>(requested_obj) + field_offset);
813     assert(bottom <= requested_field_addr && requested_field_addr < top, "range check");
814 
815     // Mark this field in the bitmap
816     BitMap::idx_t idx = requested_field_addr - bottom;
817     heap_info->ptrmap()->set_bit(idx);
818     num_non_null_ptrs ++;
819     max_idx = MAX2(max_idx, idx);
820 
821     // Set the native pointer to the requested address of the metadata (at runtime, the metadata will have
822     // this address if the RO/RW regions are mapped at the default location).
823 
824     Metadata** buffered_field_addr = requested_addr_to_buffered_addr(requested_field_addr);
825     Metadata* native_ptr = *buffered_field_addr;
826     guarantee(native_ptr != nullptr, "sanity");
827 
828     if (RegeneratedClasses::has_been_regenerated(native_ptr)) {
829       native_ptr = RegeneratedClasses::get_regenerated_object(native_ptr);
830     }
831 
832     guarantee(ArchiveBuilder::current()->has_been_archived((address)native_ptr),
833               "Metadata %p should have been archived", native_ptr);
834 
835     if (RegeneratedClasses::has_been_regenerated((address)native_ptr)) {
836       native_ptr = (Metadata*)RegeneratedClasses::get_regenerated_object((address)native_ptr);
837     }
838 
839     address buffered_native_ptr = ArchiveBuilder::current()->get_buffered_addr((address)native_ptr);
840     address requested_native_ptr = ArchiveBuilder::current()->to_requested(buffered_native_ptr);
841     *buffered_field_addr = (Metadata*)requested_native_ptr;
842   }
843 
844   heap_info->ptrmap()->resize(max_idx + 1);
845   log_info(aot, heap)("calculate_ptrmap: marked %d non-null native pointers for heap region (%zu bits)",
846                       num_non_null_ptrs, size_t(heap_info->ptrmap()->size()));
847 }
848 
849 #endif // INCLUDE_CDS_JAVA_HEAP