1 /*
   2  * Copyright (c) 2018, 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/aotMetaspace.hpp"
  26 #include "cds/aotStreamedHeapLoader.hpp"
  27 #include "cds/aotThread.hpp"
  28 #include "cds/cdsConfig.hpp"
  29 #include "cds/filemap.hpp"
  30 #include "cds/heapShared.inline.hpp"
  31 #include "classfile/classLoaderDataShared.hpp"
  32 #include "classfile/javaClasses.inline.hpp"
  33 #include "classfile/stringTable.hpp"
  34 #include "classfile/vmClasses.hpp"
  35 #include "gc/shared/collectedHeap.inline.hpp"
  36 #include "gc/shared/oopStorage.inline.hpp"
  37 #include "gc/shared/oopStorageSet.inline.hpp"
  38 #include "logging/log.hpp"
  39 #include "memory/iterator.inline.hpp"
  40 #include "memory/oopFactory.hpp"
  41 #include "oops/access.inline.hpp"
  42 #include "oops/objArrayOop.inline.hpp"
  43 #include "oops/oop.inline.hpp"
  44 #include "runtime/globals.hpp"
  45 #include "runtime/globals_extension.hpp"
  46 #include "runtime/handles.inline.hpp"
  47 #include "runtime/java.hpp"
  48 #include "runtime/mutex.hpp"
  49 #include "runtime/thread.hpp"
  50 #include "utilities/bitMap.inline.hpp"
  51 #include "utilities/exceptions.hpp"
  52 #include "utilities/globalDefinitions.hpp"
  53 #include "utilities/stack.inline.hpp"
  54 #include "utilities/ticks.hpp"
  55 
  56 #include <type_traits>
  57 
  58 #if INCLUDE_CDS_JAVA_HEAP
  59 
  60 FileMapRegion* AOTStreamedHeapLoader::_heap_region;
  61 FileMapRegion* AOTStreamedHeapLoader::_bitmap_region;
  62 int* AOTStreamedHeapLoader::_roots_archive;
  63 OopHandle AOTStreamedHeapLoader::_roots;
  64 BitMapView AOTStreamedHeapLoader::_oopmap;
  65 bool AOTStreamedHeapLoader::_is_in_use;
  66 int AOTStreamedHeapLoader::_previous_batch_last_object_index;
  67 int AOTStreamedHeapLoader::_current_batch_last_object_index;
  68 int AOTStreamedHeapLoader::_current_root_index;
  69 size_t AOTStreamedHeapLoader::_allocated_words;
  70 bool AOTStreamedHeapLoader::_allow_gc;
  71 bool AOTStreamedHeapLoader::_objects_are_handles;
  72 size_t AOTStreamedHeapLoader::_num_archived_objects;
  73 int AOTStreamedHeapLoader::_num_roots;
  74 size_t AOTStreamedHeapLoader::_heap_region_used;
  75 bool AOTStreamedHeapLoader::_loading_all_objects;
  76 
  77 size_t* AOTStreamedHeapLoader::_object_index_to_buffer_offset_table;
  78 void** AOTStreamedHeapLoader::_object_index_to_heap_object_table;
  79 int* AOTStreamedHeapLoader::_root_highest_object_index_table;
  80 
  81 bool AOTStreamedHeapLoader::_waiting_for_iterator;
  82 bool AOTStreamedHeapLoader::_swapping_root_format;
  83 
  84 static uint64_t _early_materialization_time_ns = 0;
  85 static uint64_t _late_materialization_time_ns = 0;
  86 static uint64_t _final_materialization_time_ns = 0;
  87 static uint64_t _cleanup_materialization_time_ns = 0;
  88 static volatile uint64_t _accumulated_lazy_materialization_time_ns = 0;
  89 static Ticks _materialization_start_ticks;
  90 
  91 int AOTStreamedHeapLoader::object_index_for_root_index(int root_index) {
  92   return _roots_archive[root_index];
  93 }
  94 
  95 int AOTStreamedHeapLoader::highest_object_index_for_root_index(int root_index) {
  96   return _root_highest_object_index_table[root_index];
  97 }
  98 
  99 size_t AOTStreamedHeapLoader::buffer_offset_for_object_index(int object_index) {
 100   return _object_index_to_buffer_offset_table[object_index];
 101 }
 102 
 103 oopDesc* AOTStreamedHeapLoader::archive_object_for_object_index(int object_index) {
 104   size_t buffer_offset = buffer_offset_for_object_index(object_index);
 105   address bottom = (address)_heap_region->mapped_base();
 106   return (oopDesc*)(bottom + buffer_offset);
 107 }
 108 
 109 size_t AOTStreamedHeapLoader::buffer_offset_for_archive_object(oopDesc* archive_object) {
 110   address bottom = (address)_heap_region->mapped_base();
 111   return size_t(archive_object) - size_t(bottom);
 112 }
 113 
 114 template <bool use_coops>
 115 BitMap::idx_t AOTStreamedHeapLoader::obj_bit_idx_for_buffer_offset(size_t buffer_offset) {
 116   if constexpr (use_coops) {
 117     return BitMap::idx_t(buffer_offset / sizeof(narrowOop));
 118   } else {
 119     return BitMap::idx_t(buffer_offset / sizeof(HeapWord));
 120   }
 121 }
 122 
 123 oop AOTStreamedHeapLoader::heap_object_for_object_index(int object_index) {
 124   assert(object_index >= 0 && object_index <= (int)_num_archived_objects,
 125          "Heap object reference out of index: %d", object_index);
 126 
 127   if (_objects_are_handles) {
 128     oop* handle = (oop*)_object_index_to_heap_object_table[object_index];
 129     if (handle == nullptr) {
 130       return nullptr;
 131     }
 132     return NativeAccess<>::oop_load(handle);
 133   } else {
 134     return cast_to_oop(_object_index_to_heap_object_table[object_index]);
 135   }
 136 }
 137 
 138 void AOTStreamedHeapLoader::set_heap_object_for_object_index(int object_index, oop heap_object) {
 139   assert(heap_object_for_object_index(object_index) == nullptr, "Should only set once with this API");
 140   if (_objects_are_handles) {
 141     oop* handle = Universe::vm_global()->allocate();
 142     NativeAccess<>::oop_store(handle, heap_object);
 143     _object_index_to_heap_object_table[object_index] = (void*)handle;
 144   } else {
 145     _object_index_to_heap_object_table[object_index] = cast_from_oop<void*>(heap_object);
 146   }
 147 }
 148 
 149 int AOTStreamedHeapLoader::archived_string_value_object_index(oopDesc* archive_object) {
 150     assert(archive_object->klass() == vmClasses::String_klass(), "Must be an archived string");
 151     address archive_string_value_addr = (address)archive_object + java_lang_String::value_offset();
 152     return UseCompressedOops ? *(int*)archive_string_value_addr : (int)*(int64_t*)archive_string_value_addr;
 153 }
 154 
 155 static int archive_array_length(oopDesc* archive_array) {
 156   return *(int*)(address(archive_array) + arrayOopDesc::length_offset_in_bytes());
 157 }
 158 
 159 static size_t archive_object_size(oopDesc* archive_object) {
 160   Klass* klass = archive_object->klass();
 161   int lh = klass->layout_helper();
 162 
 163   if (Klass::layout_helper_is_instance(lh)) {
 164     // Instance
 165     if (Klass::layout_helper_needs_slow_path(lh)) {
 166       return ((size_t*)(archive_object))[-1];
 167     } else {
 168       size_t size = (size_t)Klass::layout_helper_size_in_bytes(lh) >> LogHeapWordSize;
 169       if (UseCompactObjectHeaders && archive_object->mark().is_expanded() && klass->expand_for_hash(archive_object, archive_object->mark())) {
 170         size = align_object_size(size + 1);
 171       }
 172       return size;
 173     }
 174   } else if (Klass::layout_helper_is_array(lh)) {
 175     // Array
 176     size_t size_in_bytes;
 177     size_t array_length = (size_t)archive_array_length(archive_object);
 178     size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
 179     size_in_bytes += (size_t)Klass::layout_helper_header_size(lh);
 180 
 181     size_t size = align_up(size_in_bytes, (size_t)MinObjAlignmentInBytes) / HeapWordSize;
 182     if (UseCompactObjectHeaders && archive_object->mark().is_expanded() && klass->expand_for_hash(archive_object, archive_object->mark())) {
 183       size = align_object_size(size + 1);
 184     }
 185     return size;
 186   } else {
 187     // Other
 188     return ((size_t*)(archive_object))[-1];
 189   }
 190 }
 191 
 192 oop AOTStreamedHeapLoader::allocate_object(oopDesc* archive_object, markWord mark, size_t size, TRAPS) {
 193   assert(!archive_object->is_stackChunk(), "no such objects are archived");
 194 
 195   oop heap_object;
 196 
 197   Klass* klass = archive_object->klass();
 198   assert(!(UseCompactObjectHeaders && mark.is_hashed_not_expanded()), "Must not be hashed/not-expanded");
 199   if (klass->is_mirror_instance_klass()) {
 200     size_t base_size = size;
 201     assert(!(UseCompactObjectHeaders && mark.is_not_hashed_expanded()), "should not happen");
 202     heap_object = Universe::heap()->class_allocate(klass, size, base_size, CHECK_NULL);
 203   } else if (klass->is_instance_klass()) {
 204     heap_object = Universe::heap()->obj_allocate(klass, size, CHECK_NULL);
 205   } else {
 206     assert(klass->is_array_klass(), "must be");
 207     int length = archive_array_length(archive_object);
 208     bool do_zero = klass->is_objArray_klass();
 209     heap_object = Universe::heap()->array_allocate(klass, size, length, do_zero, CHECK_NULL);
 210   }
 211 
 212   heap_object->set_mark(mark);
 213 
 214   return heap_object;
 215 }
 216 
 217 void AOTStreamedHeapLoader::install_root(int root_index, oop heap_object) {
 218   objArrayOop roots = objArrayOop(_roots.resolve());
 219   OrderAccess::release(); // Once the store below publishes an object, it can be concurrently picked up by another thread without using the lock
 220   roots->obj_at_put(root_index, heap_object);
 221 }
 222 
 223 void AOTStreamedHeapLoader::TracingObjectLoader::wait_for_iterator() {
 224   if (JavaThread::current()->is_active_Java_thread()) {
 225     // When the main thread has bootstrapped past the point of allowing safepoints,
 226     // we can and indeed have to use safepoint checking waiting.
 227     AOTHeapLoading_lock->wait();
 228   } else {
 229     // If we have no bootstrapped the main thread far enough, then we cannot and
 230     // indeed also don't need to perform safepoint checking waiting.
 231     AOTHeapLoading_lock->wait_without_safepoint_check();
 232   }
 233 }
 234 
 235 // Link object after copying in-place
 236 template <typename LinkerT>
 237 class AOTStreamedHeapLoader::InPlaceLinkingOopClosure : public BasicOopIterateClosure {
 238 private:
 239   oop _obj;
 240   LinkerT _linker;
 241 
 242 public:
 243   InPlaceLinkingOopClosure(oop obj, LinkerT linker)
 244     : _obj(obj),
 245       _linker(linker) {
 246   }
 247 
 248   virtual void do_oop(oop* p) { do_oop_work(p, (int)*(intptr_t*)p); }
 249   virtual void do_oop(narrowOop* p) { do_oop_work(p, *(int*)p); }
 250 
 251   template <typename T>
 252   void do_oop_work(T* p, int object_index) {
 253     int p_offset = pointer_delta_as_int((address)p, cast_from_oop<address>(_obj));
 254     oop pointee = _linker(p_offset, object_index);
 255     if (pointee != nullptr) {
 256       _obj->obj_field_put_access<IS_DEST_UNINITIALIZED>((int)p_offset, pointee);
 257     }
 258   }
 259 };
 260 
 261 template <bool use_coops, typename LinkerT>
 262 void AOTStreamedHeapLoader::copy_payload_carefully(oopDesc* archive_object,
 263                                                    oop heap_object,
 264                                                    BitMap::idx_t header_bit,
 265                                                    BitMap::idx_t start_bit,
 266                                                    BitMap::idx_t end_bit,
 267                                                    LinkerT linker) {
 268   using RawElementT = std::conditional_t<use_coops, int32_t, int64_t>;
 269   using OopElementT = std::conditional_t<use_coops, narrowOop, oop>;
 270 
 271   BitMap::idx_t unfinished_bit = start_bit;
 272   BitMap::idx_t next_reference_bit = _oopmap.find_first_set_bit(unfinished_bit, end_bit);
 273 
 274   // Fill in heap object bytes
 275   while (unfinished_bit < end_bit) {
 276     assert(unfinished_bit >= start_bit && unfinished_bit < end_bit, "out of bounds copying");
 277 
 278     // This is the address of the pointee inside the input stream
 279     size_t payload_offset = unfinished_bit - header_bit;
 280     RawElementT* archive_payload_addr = ((RawElementT*)archive_object) + payload_offset;
 281     RawElementT* heap_payload_addr = cast_from_oop<RawElementT*>(heap_object) + payload_offset;
 282 
 283     assert(heap_payload_addr >= cast_from_oop<RawElementT*>(heap_object) &&
 284            (HeapWord*)heap_payload_addr < cast_from_oop<HeapWord*>(heap_object) + heap_object->size(),
 285            "Out of bounds copying");
 286 
 287     if (next_reference_bit > unfinished_bit) {
 288       // Primitive bytes available
 289       size_t primitive_elements = next_reference_bit - unfinished_bit;
 290       size_t primitive_bytes = primitive_elements * sizeof(RawElementT);
 291       ::memcpy(heap_payload_addr, archive_payload_addr, primitive_bytes);
 292 
 293       unfinished_bit = next_reference_bit;
 294     } else {
 295       // Encountered reference
 296       RawElementT* archive_p = (RawElementT*)archive_payload_addr;
 297       OopElementT* heap_p = (OopElementT*)heap_payload_addr;
 298       int pointee_object_index = (int)*archive_p;
 299       int heap_p_offset = pointer_delta_as_int((address)heap_p, cast_from_oop<address>(heap_object));
 300 
 301       // The object index is retrieved from the archive, not the heap object. This is
 302       // important after GC is enabled. Concurrent GC threads may scan references in the
 303       // heap for various reasons after this point. Therefore, it is not okay to first copy
 304       // the object index from a reference location in the archived object payload to a
 305       // corresponding location in the heap object payload, and then fix it up afterwards to
 306       // refer to a heap object. This is why this code iterates carefully over object references
 307       // in the archived object, linking them one by one, without clobbering the reference
 308       // locations in the heap objects with anything other than transitions from null to the
 309       // intended linked object.
 310       oop obj = linker(heap_p_offset, pointee_object_index);
 311       if (obj != nullptr) {
 312         heap_object->obj_field_put(heap_p_offset, obj);
 313       }
 314 
 315       unfinished_bit++;
 316       next_reference_bit = _oopmap.find_first_set_bit(unfinished_bit, end_bit);
 317     }
 318   }
 319 }
 320 
 321 template <bool use_coops, typename LinkerT>
 322 void AOTStreamedHeapLoader::copy_object_impl(oopDesc* archive_object,
 323                                              oop heap_object,
 324                                              size_t size,
 325                                              LinkerT linker) {
 326   if (!_allow_gc) {
 327     // Without concurrent GC running, we can copy incorrect object references
 328     // and metadata references into the heap object and then fix them up in-place.
 329     size_t offset = 1;
 330     size_t payload_size = size - offset;
 331     HeapWord* archive_start = ((HeapWord*)archive_object);
 332     HeapWord* heap_start = cast_from_oop<HeapWord*>(heap_object);
 333 
 334     Copy::disjoint_words(archive_start + offset, heap_start + offset, payload_size);
 335 
 336     if (UseCompactObjectHeaders) {
 337       // The copying might have missed the first 4 bytes of payload/arraylength, copy that also.
 338       *(reinterpret_cast<jint*>(heap_start) + 1) = *(reinterpret_cast<jint*>(archive_start) + 1);
 339     }
 340 
 341     // In-place linking fixes up object indices from references of the heap object,
 342     // and patches them up to refer to objects. This can be done because we just copied
 343     // the payload of the object from the archive to the heap object, including the
 344     // reference object indices. However, this is only okay to do before the GC can run.
 345     // A concurrent GC thread might racingly read the object payload after GC is enabled.
 346     InPlaceLinkingOopClosure cl(heap_object, linker);
 347     heap_object->oop_iterate(&cl);
 348     HeapShared::remap_loaded_metadata(heap_object);
 349     return;
 350   }
 351 
 352   // When a concurrent GC may be running, we take care not to copy incorrect oops,
 353   // narrowOops or Metadata* into the heap objects. Transitions go from 0 to the
 354   // intended runtime linked values only.
 355   size_t word_scale = use_coops ? 2 : 1;
 356   using RawElementT = std::conditional_t<use_coops, int32_t, int64_t>;
 357 
 358   // Skip the markWord; it is set at allocation time
 359   size_t header_size = (UseCompactObjectHeaders && use_coops) ? 1 : word_scale;
 360 
 361   size_t buffer_offset = buffer_offset_for_archive_object(archive_object);
 362   const BitMap::idx_t header_bit = obj_bit_idx_for_buffer_offset<use_coops>(buffer_offset);
 363   const BitMap::idx_t start_bit = header_bit + header_size;
 364   const BitMap::idx_t end_bit = header_bit + size * word_scale;
 365 
 366   BitMap::idx_t curr_bit = start_bit;
 367 
 368   if (UseCompactObjectHeaders && !use_coops) {
 369     // Copy first 4 primitive bytes.
 370     jint* archive_start = reinterpret_cast<jint*>(archive_object);
 371     HeapWord* heap_start = cast_from_oop<HeapWord*>(heap_object);
 372     *(reinterpret_cast<jint*>(heap_start) + 1) = *(archive_start + 1);
 373   }
 374 
 375   // We are a bit paranoid about GC or other safepointing operations observing
 376   // shady metadata fields from the archive that do not point at real metadata.
 377   // We deal with this by explicitly reading the requested address from the
 378   // archive and fixing it to real Metadata before writing it into the heap object.
 379   HeapShared::do_metadata_offsets(heap_object, [&](int metadata_offset) {
 380     BitMap::idx_t metadata_field_idx = header_bit + (size_t)metadata_offset / sizeof(RawElementT);
 381     BitMap::idx_t skip = word_scale;
 382     assert(metadata_field_idx >= start_bit && metadata_field_idx + skip <= end_bit,
 383            "Metadata field out of bounds");
 384 
 385     // Copy payload before metadata field
 386     copy_payload_carefully<use_coops>(archive_object,
 387                                       heap_object,
 388                                       header_bit,
 389                                       curr_bit,
 390                                       metadata_field_idx,
 391                                       linker);
 392 
 393     // Copy metadata field
 394     Metadata* const archive_metadata = *(Metadata**)(uintptr_t(archive_object) + (size_t)metadata_offset);
 395     Metadata* const runtime_metadata = archive_metadata != nullptr
 396         ? (Metadata*)(address(archive_metadata) + AOTMetaspace::relocation_delta())
 397         : nullptr;
 398     assert(runtime_metadata == nullptr || AOTMetaspace::in_aot_cache(runtime_metadata), "Invalid metadata pointer");
 399     DEBUG_ONLY(Metadata* const previous_metadata = heap_object->metadata_field(metadata_offset);)
 400     assert(previous_metadata == nullptr || previous_metadata == runtime_metadata, "Should not observe transient values");
 401     heap_object->metadata_field_put(metadata_offset, runtime_metadata);
 402     curr_bit = metadata_field_idx + skip;
 403   });
 404 
 405   // Copy trailing metadata after the last metadata word. This is usually doing
 406   // all the copying.
 407   copy_payload_carefully<use_coops>(archive_object,
 408                                     heap_object,
 409                                     header_bit,
 410                                     curr_bit,
 411                                     end_bit,
 412                                     linker);
 413 }
 414 
 415 void AOTStreamedHeapLoader::copy_object_eager_linking(oopDesc* archive_object, oop heap_object, size_t size) {
 416   auto linker = [&](int p_offset, int pointee_object_index) {
 417     oop obj = AOTStreamedHeapLoader::heap_object_for_object_index(pointee_object_index);
 418     assert(pointee_object_index == 0 || obj != nullptr, "Eager object loading should only encounter already allocated links");
 419     return obj;
 420   };
 421   if (UseCompressedOops) {
 422     copy_object_impl<true>(archive_object, heap_object, size, linker);
 423   } else {
 424     copy_object_impl<false>(archive_object, heap_object, size, linker);
 425   }
 426 }
 427 
 428 void AOTStreamedHeapLoader::TracingObjectLoader::copy_object_lazy_linking(int object_index,
 429                                                                           oopDesc* archive_object,
 430                                                                           oop heap_object,
 431                                                                           size_t size,
 432                                                                           Stack<AOTHeapTraversalEntry, mtClassShared>& dfs_stack) {
 433   auto linker = [&](int p_offset, int pointee_object_index) {
 434     dfs_stack.push({pointee_object_index, object_index, p_offset});
 435 
 436     // The tracing linker is a bit lazy and mutates the reference fields in its traversal.
 437     // Returning null means don't link now.
 438     return oop(nullptr);
 439   };
 440   if (UseCompressedOops) {
 441     copy_object_impl<true>(archive_object, heap_object, size, linker);
 442   } else {
 443     copy_object_impl<false>(archive_object, heap_object, size, linker);
 444   }
 445 }
 446 
 447 oop AOTStreamedHeapLoader::TracingObjectLoader::materialize_object_inner(int object_index, Stack<AOTHeapTraversalEntry, mtClassShared>& dfs_stack, TRAPS) {
 448   // Allocate object
 449   oopDesc* archive_object = archive_object_for_object_index(object_index);
 450   size_t size = archive_object_size(archive_object);
 451   markWord mark = archive_object->mark();
 452 
 453   // The markWord is marked if the object is a String and it should be interned,
 454   // make sure to unmark it before allocating memory for the object.
 455   bool string_intern = mark.is_marked();
 456   mark = mark.set_unmarked();
 457 
 458   oop heap_object;
 459 
 460   if (string_intern) {
 461     int value_object_index = archived_string_value_object_index(archive_object);
 462 
 463     // Materialize the value object.
 464     (void)materialize_object(value_object_index, dfs_stack, CHECK_NULL);
 465 
 466     // Allocate and link the string.
 467     heap_object = allocate_object(archive_object, mark, size, CHECK_NULL);
 468     copy_object_eager_linking(archive_object, heap_object, size);
 469 
 470     assert(java_lang_String::value(heap_object) == heap_object_for_object_index(value_object_index), "Linker should have linked this correctly");
 471 
 472     // Replace the string with interned string
 473     heap_object = StringTable::intern(heap_object, CHECK_NULL);
 474   } else {
 475     heap_object = allocate_object(archive_object, mark, size, CHECK_NULL);
 476 
 477     // Fill in object contents
 478     copy_object_lazy_linking(object_index, archive_object, heap_object, size, dfs_stack);
 479   }
 480 
 481   // Install forwarding
 482   set_heap_object_for_object_index(object_index, heap_object);
 483 
 484   return heap_object;
 485 }
 486 
 487 oop AOTStreamedHeapLoader::TracingObjectLoader::materialize_object(int object_index, Stack<AOTHeapTraversalEntry, mtClassShared>& dfs_stack, TRAPS) {
 488   if (object_index <= _previous_batch_last_object_index) {
 489     // The transitive closure of this object has been materialized; no need to do anything
 490     return heap_object_for_object_index(object_index);
 491   }
 492 
 493   if (object_index <= _current_batch_last_object_index) {
 494     // The AOTThread is currently materializing this object and its transitive closure; only need to wait for it to complete
 495     _waiting_for_iterator = true;
 496     while (object_index > _previous_batch_last_object_index) {
 497       wait_for_iterator();
 498     }
 499     _waiting_for_iterator = false;
 500 
 501     // Notify the AOT thread if it is waiting for tracing to finish
 502     AOTHeapLoading_lock->notify_all();
 503     return heap_object_for_object_index(object_index);;
 504   }
 505 
 506   oop heap_object = heap_object_for_object_index(object_index);
 507   if (heap_object != nullptr) {
 508     // Already materialized by mutator
 509     return heap_object;
 510   }
 511 
 512   return materialize_object_inner(object_index, dfs_stack, THREAD);
 513 }
 514 
 515 void AOTStreamedHeapLoader::TracingObjectLoader::drain_stack(Stack<AOTHeapTraversalEntry, mtClassShared>& dfs_stack, TRAPS) {
 516   while (!dfs_stack.is_empty()) {
 517     AOTHeapTraversalEntry entry = dfs_stack.pop();
 518     int pointee_object_index = entry._pointee_object_index;
 519     oop pointee_heap_object = materialize_object(pointee_object_index, dfs_stack, CHECK);
 520     oop heap_object = heap_object_for_object_index(entry._base_object_index);
 521     if (_allow_gc) {
 522       heap_object->obj_field_put(entry._heap_field_offset_bytes, pointee_heap_object);
 523     } else {
 524       heap_object->obj_field_put_access<IS_DEST_UNINITIALIZED>(entry._heap_field_offset_bytes, pointee_heap_object);
 525     }
 526   }
 527 }
 528 
 529 oop AOTStreamedHeapLoader::TracingObjectLoader::materialize_object_transitive(int object_index, Stack<AOTHeapTraversalEntry, mtClassShared>& dfs_stack, TRAPS) {
 530   assert_locked_or_safepoint(AOTHeapLoading_lock);
 531   while (_waiting_for_iterator) {
 532     wait_for_iterator();
 533   }
 534 
 535   auto handlized_materialize_object = [&](TRAPS) {
 536     oop obj = materialize_object(object_index, dfs_stack, CHECK_(Handle()));
 537     return Handle(THREAD, obj);
 538   };
 539 
 540   Handle result = handlized_materialize_object(CHECK_NULL);
 541   drain_stack(dfs_stack, CHECK_NULL);
 542 
 543   return result();
 544 }
 545 
 546 oop AOTStreamedHeapLoader::TracingObjectLoader::materialize_root(int root_index, Stack<AOTHeapTraversalEntry, mtClassShared>& dfs_stack, TRAPS) {
 547   int root_object_index = object_index_for_root_index(root_index);
 548   oop root = materialize_object_transitive(root_object_index, dfs_stack, CHECK_NULL);
 549   install_root(root_index, root);
 550 
 551   return root;
 552 }
 553 
 554 int oop_handle_cmp(const void* left, const void* right) {
 555   oop* left_handle = *(oop**)left;
 556   oop* right_handle = *(oop**)right;
 557 
 558   if (right_handle > left_handle) {
 559     return -1;
 560   } else if (left_handle > right_handle) {
 561     return 1;
 562   }
 563 
 564   return 0;
 565 }
 566 
 567 // The range is inclusive
 568 void AOTStreamedHeapLoader::IterativeObjectLoader::initialize_range(int first_object_index, int last_object_index, TRAPS) {
 569   for (int i = first_object_index; i <= last_object_index; ++i) {
 570     oopDesc* archive_object = archive_object_for_object_index(i);
 571     markWord mark = archive_object->mark();
 572     bool string_intern = mark.is_marked();
 573     if (string_intern) {
 574       int value_object_index = archived_string_value_object_index(archive_object);
 575       if (value_object_index == i + 1) {
 576         // Interned strings are eagerly materialized in the allocation phase, so there is
 577         // nothing else to do for interned strings here for the string nor its value array.
 578         i++;
 579       }
 580       continue;
 581     }
 582     size_t size = archive_object_size(archive_object);
 583     oop heap_object = heap_object_for_object_index(i);
 584     copy_object_eager_linking(archive_object, heap_object, size);
 585   }
 586 }
 587 
 588 // The range is inclusive
 589 size_t AOTStreamedHeapLoader::IterativeObjectLoader::materialize_range(int first_object_index, int last_object_index, TRAPS) {
 590   GrowableArrayCHeap<int, mtClassShared> lazy_object_indices(0);
 591   size_t materialized_words = 0;
 592 
 593   for (int i = first_object_index; i <= last_object_index; ++i) {
 594     oopDesc* archive_object = archive_object_for_object_index(i);
 595     markWord mark = archive_object->mark();
 596 
 597     // The markWord is marked if the object is a String and it should be interned,
 598     // make sure to unmark it before allocating memory for the object.
 599     bool string_intern = mark.is_marked();
 600     mark = mark.set_unmarked();
 601 
 602     size_t size = archive_object_size(archive_object);
 603     materialized_words += size;
 604 
 605     oop heap_object = heap_object_for_object_index(i);
 606     if (heap_object != nullptr) {
 607       // Lazy loading has already initialized the object; we must not mutate it
 608       lazy_object_indices.append(i);
 609       continue;
 610     }
 611 
 612     if (!string_intern) {
 613      // The normal case; no lazy loading have loaded the object yet
 614       heap_object = allocate_object(archive_object, mark, size, CHECK_0);
 615       set_heap_object_for_object_index(i, heap_object);
 616       continue;
 617     }
 618 
 619     // Eagerly materialize interned strings to ensure that objects earlier than the string
 620     // in a batch get linked to the intended interned string, and not a copy.
 621     int value_object_index = archived_string_value_object_index(archive_object);
 622 
 623     bool is_normal_interned_string = value_object_index == i + 1;
 624 
 625     if (value_object_index < first_object_index) {
 626       // If materialized in a previous batch, the value should already be allocated and initialized.
 627       assert(heap_object_for_object_index(value_object_index) != nullptr, "should be materialized");
 628     } else {
 629       // Materialize the value object.
 630       oopDesc* archive_value_object = archive_object_for_object_index(value_object_index);
 631       markWord value_mark = archive_value_object->mark();
 632       size_t value_size = archive_object_size(archive_value_object);
 633       oop value_heap_object;
 634 
 635       if (is_normal_interned_string) {
 636         // The common case: the value is next to the string. This happens when only the interned
 637         // string points to its value character array.
 638         assert(value_object_index <= last_object_index, "Must be within this batch: %d <= %d", value_object_index, last_object_index);
 639         value_heap_object = allocate_object(archive_value_object, value_mark, value_size, CHECK_0);
 640         set_heap_object_for_object_index(value_object_index, value_heap_object);
 641         materialized_words += value_size;
 642       } else {
 643         // In the uncommon case, multiple strings point to the value of an interned string.
 644         // The string can then be earlier in the batch.
 645         assert(value_object_index < i, "surprising index");
 646         value_heap_object = heap_object_for_object_index(value_object_index);
 647       }
 648 
 649       copy_object_eager_linking(archive_value_object, value_heap_object, value_size);
 650     }
 651     // Allocate and link the string.
 652     heap_object = allocate_object(archive_object, mark, size, CHECK_0);
 653     copy_object_eager_linking(archive_object, heap_object, size);
 654 
 655     assert(java_lang_String::value(heap_object) == heap_object_for_object_index(value_object_index), "Linker should have linked this correctly");
 656 
 657     // Replace the string with interned string
 658     heap_object = StringTable::intern(heap_object, CHECK_0);
 659     set_heap_object_for_object_index(i, heap_object);
 660 
 661     if (is_normal_interned_string) {
 662       // Skip over the string value, already materialized
 663       i++;
 664     }
 665   }
 666 
 667   if (lazy_object_indices.is_empty()) {
 668     // Normal case; no sprinkled lazy objects in the root subgraph
 669     initialize_range(first_object_index, last_object_index, CHECK_0);
 670   } else {
 671     // The user lazy initialized some objects that are already initialized; we have to initialize around them
 672     // to make sure they are not mutated.
 673     int previous_object_index = first_object_index - 1; // Exclusive start of initialization slice
 674     for (int i = 0; i < lazy_object_indices.length(); ++i) {
 675       int lazy_object_index = lazy_object_indices.at(i);
 676       int slice_start_object_index = previous_object_index;
 677       int slice_end_object_index = lazy_object_index;
 678 
 679       if (slice_end_object_index - slice_start_object_index > 1) { // Both markers are exclusive
 680         initialize_range(slice_start_object_index + 1, slice_end_object_index - 1, CHECK_0);
 681       }
 682       previous_object_index = lazy_object_index;
 683     }
 684     // Process tail range
 685     if (last_object_index - previous_object_index > 0) {
 686       initialize_range(previous_object_index + 1, last_object_index, CHECK_0);
 687     }
 688   }
 689 
 690   return materialized_words;
 691 }
 692 
 693 bool AOTStreamedHeapLoader::IterativeObjectLoader::has_more() {
 694   return _current_root_index < _num_roots;
 695 }
 696 
 697 void AOTStreamedHeapLoader::IterativeObjectLoader::materialize_next_batch(TRAPS) {
 698   assert(has_more(), "only materialize if there is something to materialize");
 699 
 700   int min_batch_objects = 128;
 701   int from_root_index = _current_root_index;
 702   int max_to_root_index = _num_roots - 1;
 703   int until_root_index = from_root_index;
 704   int highest_object_index;
 705 
 706   // Expand the batch size from one root, to N roots until we cross 128 objects in total
 707   for (;;) {
 708     highest_object_index = highest_object_index_for_root_index(until_root_index);
 709     if (highest_object_index - _previous_batch_last_object_index >= min_batch_objects) {
 710       break;
 711     }
 712     if (until_root_index == max_to_root_index) {
 713       break;
 714     }
 715     until_root_index++;
 716   }
 717 
 718   oop root = nullptr;
 719 
 720   // Materialize objects of necessary, representing the transitive closure of the root
 721   if (highest_object_index > _previous_batch_last_object_index) {
 722     while (_swapping_root_format) {
 723       // When the roots are being upgraded to use handles, it is not safe to racingly
 724       // iterate over the object; we must wait. Setting the current batch last object index
 725       // to something other than the previous batch last object index indicates to the
 726       // root swapping that there is current iteration ongoing.
 727       AOTHeapLoading_lock->wait();
 728     }
 729     int first_object_index = _previous_batch_last_object_index + 1;
 730     _current_batch_last_object_index = highest_object_index;
 731     size_t allocated_words;
 732     {
 733       MutexUnlocker ml(AOTHeapLoading_lock, Mutex::_safepoint_check_flag);
 734       allocated_words = materialize_range(first_object_index, highest_object_index, CHECK);
 735     }
 736     _allocated_words += allocated_words;
 737     _previous_batch_last_object_index = _current_batch_last_object_index;
 738     if (_waiting_for_iterator) {
 739       // If tracer is waiting, let it know at the next point of unlocking that the root
 740       // set it waited for has been processed now.
 741       AOTHeapLoading_lock->notify_all();
 742     }
 743   }
 744 
 745   // Install the root
 746   for (int i = from_root_index; i <= until_root_index; ++i) {
 747     int root_object_index = object_index_for_root_index(i);
 748     root = heap_object_for_object_index(root_object_index);
 749     install_root(i, root);
 750     ++_current_root_index;
 751   }
 752 }
 753 
 754 bool AOTStreamedHeapLoader::materialize_early(TRAPS) {
 755   Ticks start = Ticks::now();
 756 
 757   // Only help with early materialization from the AOT thread if the heap archive can be allocated
 758   // without the need for a GC. Otherwise, do lazy loading until GC is enabled later in the bootstrapping.
 759   size_t bootstrap_max_memory = Universe::heap()->bootstrap_max_memory();
 760   size_t bootstrap_min_memory = MAX2(_heap_region_used, 2 * M);
 761 
 762   size_t before_gc_materialize_budget_bytes = (bootstrap_max_memory > bootstrap_min_memory) ? bootstrap_max_memory - bootstrap_min_memory : 0;
 763   size_t before_gc_materialize_budget_words = before_gc_materialize_budget_bytes / HeapWordSize;
 764 
 765   log_info(aot, heap)("Max bootstrapping memory: %zuM, min bootstrapping memory: %zuM, selected budget: %zuM",
 766                       bootstrap_max_memory / M, bootstrap_min_memory / M, before_gc_materialize_budget_bytes / M);
 767 
 768   while (IterativeObjectLoader::has_more()) {
 769     if (_allow_gc || _allocated_words > before_gc_materialize_budget_words) {
 770       log_info(aot, heap)("Early object materialization interrupted at root %d", _current_root_index);
 771       break;
 772     }
 773 
 774     IterativeObjectLoader::materialize_next_batch(CHECK_false);
 775   }
 776 
 777   _early_materialization_time_ns = (Ticks::now() - start).nanoseconds();
 778 
 779   bool finished_before_gc_allowed = !_allow_gc && !IterativeObjectLoader::has_more();
 780 
 781   return finished_before_gc_allowed;
 782 }
 783 
 784 void AOTStreamedHeapLoader::materialize_late(TRAPS) {
 785   Ticks start = Ticks::now();
 786 
 787   // Continue materializing with GC allowed
 788 
 789   while (IterativeObjectLoader::has_more()) {
 790     IterativeObjectLoader::materialize_next_batch(CHECK);
 791   }
 792 
 793   _late_materialization_time_ns = (Ticks::now() - start).nanoseconds();
 794 }
 795 
 796 void AOTStreamedHeapLoader::cleanup() {
 797   // First ensure there is no concurrent tracing going on
 798   while (_waiting_for_iterator) {
 799     AOTHeapLoading_lock->wait();
 800   }
 801 
 802   Ticks start = Ticks::now();
 803 
 804   // Remove OopStorage roots
 805   if (_objects_are_handles) {
 806     size_t num_handles = _num_archived_objects;
 807     // Skip the null entry
 808     oop** handles = ((oop**)_object_index_to_heap_object_table) + 1;
 809     // Sort the handles so that oop storage can release them faster
 810     qsort(handles, num_handles, sizeof(oop*), (int (*)(const void*, const void*))oop_handle_cmp);
 811     size_t num_null_handles = 0;
 812     for (size_t handles_remaining = num_handles; handles_remaining != 0; --handles_remaining) {
 813       oop* handle = handles[handles_remaining - 1];
 814       if (handle == nullptr) {
 815         num_null_handles = handles_remaining;
 816         break;
 817       }
 818       NativeAccess<>::oop_store(handle, nullptr);
 819     }
 820     Universe::vm_global()->release(&handles[num_null_handles], num_handles - num_null_handles);
 821   }
 822 
 823   FREE_C_HEAP_ARRAY(void*, _object_index_to_heap_object_table);
 824 
 825   // Unmap regions
 826   FileMapInfo::current_info()->unmap_region(AOTMetaspace::hp);
 827   FileMapInfo::current_info()->unmap_region(AOTMetaspace::bm);
 828 
 829   _cleanup_materialization_time_ns = (Ticks::now() - start).nanoseconds();
 830 
 831   log_statistics();
 832 }
 833 
 834 void AOTStreamedHeapLoader::log_statistics() {
 835   uint64_t total_duration_us = (Ticks::now() - _materialization_start_ticks).microseconds();
 836   const bool is_async = _loading_all_objects && !AOTEagerlyLoadObjects;
 837   const char* const async_or_sync = is_async ? "async" : "sync";
 838   log_info(aot, heap)("start to finish materialization time: " UINT64_FORMAT "us",
 839                       total_duration_us);
 840   log_info(aot, heap)("early object materialization time (%s): " UINT64_FORMAT "us",
 841                       async_or_sync, _early_materialization_time_ns / 1000);
 842   log_info(aot, heap)("late object materialization time (%s): " UINT64_FORMAT "us",
 843                       async_or_sync, _late_materialization_time_ns / 1000);
 844   log_info(aot, heap)("object materialization cleanup time (%s): " UINT64_FORMAT "us",
 845                       async_or_sync, _cleanup_materialization_time_ns / 1000);
 846   log_info(aot, heap)("final object materialization time stall (sync): " UINT64_FORMAT "us",
 847                       _final_materialization_time_ns / 1000);
 848   log_info(aot, heap)("bootstrapping lazy materialization time (sync): " UINT64_FORMAT "us",
 849                       _accumulated_lazy_materialization_time_ns / 1000);
 850 
 851   uint64_t sync_time = _final_materialization_time_ns + _accumulated_lazy_materialization_time_ns;
 852   uint64_t async_time = _early_materialization_time_ns + _late_materialization_time_ns + _cleanup_materialization_time_ns;
 853 
 854   if (!is_async) {
 855     sync_time += async_time;
 856     async_time = 0;
 857   }
 858 
 859   log_info(aot, heap)("sync materialization time: " UINT64_FORMAT "us",
 860                       sync_time / 1000);
 861 
 862   log_info(aot, heap)("async materialization time: " UINT64_FORMAT "us",
 863                       async_time / 1000);
 864 
 865   uint64_t iterative_time = (uint64_t)(is_async ? async_time : sync_time);
 866   uint64_t materialized_bytes = _allocated_words * HeapWordSize;
 867   log_info(aot, heap)("%s materialized " UINT64_FORMAT "K (" UINT64_FORMAT "M/s)", async_or_sync,
 868                       materialized_bytes / 1024, uint64_t(materialized_bytes * UCONST64(1'000'000'000) / M / iterative_time));
 869 }
 870 
 871 void AOTStreamedHeapLoader::materialize_objects() {
 872   // We cannot handle any exception when materializing roots. Exits the VM.
 873   EXCEPTION_MARK
 874 
 875   // Objects are laid out in DFS order; DFS traverse the roots by linearly walking all objects
 876   HandleMark hm(THREAD);
 877 
 878   // Early materialization with a budget before GC is allowed
 879   MutexLocker ml(AOTHeapLoading_lock, Mutex::_safepoint_check_flag);
 880 
 881   materialize_early(CHECK);
 882   await_gc_enabled();
 883   materialize_late(CHECK);
 884   // Notify materialization is done
 885   AOTHeapLoading_lock->notify_all();
 886   cleanup();
 887 }
 888 
 889 void AOTStreamedHeapLoader::switch_object_index_to_handle(int object_index) {
 890   oop heap_object = cast_to_oop(_object_index_to_heap_object_table[object_index]);
 891   if (heap_object == nullptr) {
 892     return;
 893   }
 894 
 895   oop* handle = Universe::vm_global()->allocate();
 896   NativeAccess<>::oop_store(handle, heap_object);
 897   _object_index_to_heap_object_table[object_index] = handle;
 898 }
 899 
 900 void AOTStreamedHeapLoader::enable_gc() {
 901   if (AOTEagerlyLoadObjects && !IterativeObjectLoader::has_more()) {
 902     // Everything was loaded eagerly at early startup
 903     return;
 904   }
 905 
 906   // We cannot handle any exception when materializing roots. Exits the VM.
 907   EXCEPTION_MARK
 908 
 909   MutexLocker ml(AOTHeapLoading_lock, Mutex::_safepoint_check_flag);
 910 
 911   // First wait until no tracing is active
 912   while (_waiting_for_iterator) {
 913     AOTHeapLoading_lock->wait();
 914   }
 915 
 916   // Lock further tracing from starting
 917   _waiting_for_iterator = true;
 918 
 919   // Record iterator progress
 920   int num_handles = (int)_num_archived_objects;
 921 
 922   // Lock further iteration from starting
 923   _swapping_root_format = true;
 924 
 925   // Then wait for the iterator to stop
 926   while (_previous_batch_last_object_index != _current_batch_last_object_index) {
 927     AOTHeapLoading_lock->wait();
 928   }
 929 
 930   if (IterativeObjectLoader::has_more()) {
 931     // If there is more to be materialized, we have to upgrade the object index
 932     // to object mapping to use handles. If there isn't more to materialize, the
 933     // handle will no longer e used; they are only used to materialize objects.
 934 
 935     for (int i = 1; i <= num_handles; ++i) {
 936       // Upgrade the roots to use handles
 937       switch_object_index_to_handle(i);
 938     }
 939 
 940     // From now on, accessing the object table must be done through a handle.
 941     _objects_are_handles = true;
 942   }
 943 
 944   // Unlock tracing
 945   _waiting_for_iterator = false;
 946 
 947   // Unlock iteration
 948   _swapping_root_format = false;
 949 
 950   _allow_gc = true;
 951 
 952   AOTHeapLoading_lock->notify_all();
 953 
 954   if (AOTEagerlyLoadObjects && IterativeObjectLoader::has_more()) {
 955     materialize_late(CHECK);
 956     cleanup();
 957   }
 958 }
 959 
 960 void AOTStreamedHeapLoader::materialize_thread_object() {
 961   AOTThread::materialize_thread_object();
 962 }
 963 
 964 void AOTStreamedHeapLoader::finish_materialize_objects() {
 965   Ticks start = Ticks::now();
 966 
 967   if (_loading_all_objects) {
 968     MutexLocker ml(AOTHeapLoading_lock, Mutex::_safepoint_check_flag);
 969     // Wait for the AOT thread to finish
 970     while (IterativeObjectLoader::has_more()) {
 971       AOTHeapLoading_lock->wait();
 972     }
 973   } else {
 974     assert(!AOTEagerlyLoadObjects, "sanity");
 975     assert(_current_root_index == 0, "sanity");
 976     // Without the full module graph we have done only lazy tracing materialization.
 977     // Ensure all roots are processed here by triggering root loading on every root.
 978     for (int i = 0; i < _num_roots; ++i) {
 979       get_root(i);
 980     }
 981     cleanup();
 982   }
 983 
 984   _final_materialization_time_ns = (Ticks::now() - start).nanoseconds();
 985 }
 986 
 987 void account_lazy_materialization_time_ns(uint64_t time, const char* description, int index) {
 988   AtomicAccess::add(&_accumulated_lazy_materialization_time_ns, time);
 989   log_debug(aot, heap)("Lazy materialization of %s: %d end (" UINT64_FORMAT " us of " UINT64_FORMAT " us)", description, index, time / 1000, _accumulated_lazy_materialization_time_ns / 1000);
 990 }
 991 
 992 // Initialize an empty array of AOT heap roots; materialize them lazily
 993 void AOTStreamedHeapLoader::initialize() {
 994   EXCEPTION_MARK
 995 
 996   _materialization_start_ticks = Ticks::now();
 997 
 998   FileMapInfo::current_info()->map_bitmap_region();
 999 
1000   _heap_region = FileMapInfo::current_info()->region_at(AOTMetaspace::hp);
1001   _bitmap_region = FileMapInfo::current_info()->region_at(AOTMetaspace::bm);
1002 
1003   assert(_heap_region->used() > 0, "empty heap archive?");
1004 
1005   _is_in_use = true;
1006 
1007   // archived roots are at this offset in the stream.
1008   size_t roots_offset = FileMapInfo::current_info()->streamed_heap()->roots_offset();
1009   size_t forwarding_offset = FileMapInfo::current_info()->streamed_heap()->forwarding_offset();
1010   size_t root_highest_object_index_table_offset = FileMapInfo::current_info()->streamed_heap()->root_highest_object_index_table_offset();
1011   _num_archived_objects = FileMapInfo::current_info()->streamed_heap()->num_archived_objects();
1012 
1013   // The first int is the length of the array
1014   _roots_archive = ((int*)(((address)_heap_region->mapped_base()) + roots_offset)) + 1;
1015   _num_roots = _roots_archive[-1];
1016   _heap_region_used = _heap_region->used();
1017 
1018   // We can't retire a TLAB until the filler klass is set; set it to the archived object klass.
1019   CollectedHeap::set_filler_object_klass(vmClasses::Object_klass());
1020 
1021   objArrayOop roots = oopFactory::new_objectArray(_num_roots, CHECK);
1022   _roots = OopHandle(Universe::vm_global(), roots);
1023 
1024   _object_index_to_buffer_offset_table = (size_t*)(((address)_heap_region->mapped_base()) + forwarding_offset);
1025   // We allocate the first entry for "null"
1026   _object_index_to_heap_object_table = NEW_C_HEAP_ARRAY(void*, _num_archived_objects + 1, mtClassShared);
1027   Copy::zero_to_bytes(_object_index_to_heap_object_table, (_num_archived_objects + 1) * sizeof(void*));
1028 
1029   _root_highest_object_index_table = (int*)(((address)_heap_region->mapped_base()) + root_highest_object_index_table_offset);
1030 
1031   address start = (address)(_bitmap_region->mapped_base()) + _heap_region->oopmap_offset();
1032   _oopmap = BitMapView((BitMap::bm_word_t*)start, _heap_region->oopmap_size_in_bits());
1033 
1034 
1035   if (FLAG_IS_DEFAULT(AOTEagerlyLoadObjects)) {
1036     // Concurrency will not help much if there are no extra cores available.
1037     FLAG_SET_ERGO(AOTEagerlyLoadObjects, os::initial_active_processor_count() <= 1);
1038   }
1039 
1040   // If the full module graph is not available or the JVMTI class file load hook is on, we
1041   // will prune the object graph to not include cached objects in subgraphs that are not intended
1042   // to be loaded.
1043   _loading_all_objects = CDSConfig::is_using_full_module_graph() && !JvmtiExport::should_post_class_file_load_hook();
1044   if (!_loading_all_objects) {
1045     // When not using FMG, fall back to tracing materialization
1046     FLAG_SET_ERGO(AOTEagerlyLoadObjects, false);
1047     return;
1048   }
1049 
1050   if (AOTEagerlyLoadObjects) {
1051     // Objects are laid out in DFS order; DFS traverse the roots by linearly walking all objects
1052     HandleMark hm(THREAD);
1053 
1054     // Early materialization with a budget before GC is allowed
1055     MutexLocker ml(AOTHeapLoading_lock, Mutex::_safepoint_check_flag);
1056 
1057     bool finished_before_gc_allowed = materialize_early(CHECK);
1058     if (finished_before_gc_allowed) {
1059       cleanup();
1060     }
1061   } else {
1062     AOTThread::initialize();
1063   }
1064 }
1065 
1066 oop AOTStreamedHeapLoader::materialize_root(int root_index) {
1067   Ticks start = Ticks::now();
1068   // We cannot handle any exception when materializing a root. Exits the VM.
1069   EXCEPTION_MARK
1070   Stack<AOTHeapTraversalEntry, mtClassShared> dfs_stack;
1071   HandleMark hm(THREAD);
1072 
1073   oop result;
1074   {
1075     MutexLocker ml(AOTHeapLoading_lock, Mutex::_safepoint_check_flag);
1076 
1077     oop root = objArrayOop(_roots.resolve())->obj_at(root_index);
1078 
1079     if (root != nullptr) {
1080       // The root has already been materialized
1081       result = root;
1082     } else {
1083       // The root has not been materialized, start tracing materialization
1084       result = TracingObjectLoader::materialize_root(root_index, dfs_stack, CHECK_NULL);
1085     }
1086   }
1087 
1088   uint64_t duration = (Ticks::now() - start).nanoseconds();
1089 
1090   account_lazy_materialization_time_ns(duration, "root", root_index);
1091 
1092   return result;
1093 }
1094 
1095 oop AOTStreamedHeapLoader::get_root(int index) {
1096   oop result = objArrayOop(_roots.resolve())->obj_at(index);
1097   if (result == nullptr) {
1098     // Materialize root
1099     result = materialize_root(index);
1100   }
1101   if (result == _roots.resolve()) {
1102     // A self-reference to the roots array acts as a sentinel object for null,
1103     // indicating that the root has been cleared.
1104     result = nullptr;
1105   }
1106   // Acquire the root transitive object payload
1107   OrderAccess::acquire();
1108   return result;
1109 }
1110 
1111 void AOTStreamedHeapLoader::clear_root(int index) {
1112   // Self-reference to the roots array acts as a sentinel object for null,
1113   // indicating that the root has been cleared.
1114   objArrayOop(_roots.resolve())->obj_at_put(index, _roots.resolve());
1115 }
1116 
1117 void AOTStreamedHeapLoader::await_gc_enabled() {
1118   while (!_allow_gc) {
1119     AOTHeapLoading_lock->wait();
1120   }
1121 }
1122 
1123 void AOTStreamedHeapLoader::finish_initialization(FileMapInfo* static_mapinfo) {
1124   static_mapinfo->stream_heap_region();
1125 }
1126 
1127 AOTMapLogger::OopDataIterator* AOTStreamedHeapLoader::oop_iterator(FileMapInfo* info, address buffer_start, address buffer_end) {
1128   class StreamedLoaderOopIterator : public AOTMapLogger::OopDataIterator {
1129   private:
1130     int _current;
1131     int _next;
1132 
1133     address _buffer_start;
1134 
1135     int _num_archived_objects;
1136 
1137   public:
1138     StreamedLoaderOopIterator(address buffer_start,
1139                               int num_archived_objects)
1140       : _current(0),
1141         _next(1),
1142         _buffer_start(buffer_start),
1143         _num_archived_objects(num_archived_objects) {
1144     }
1145 
1146     AOTMapLogger::OopData capture(int dfs_index) {
1147       size_t buffered_offset = buffer_offset_for_object_index(dfs_index);
1148       address buffered_addr = _buffer_start + buffered_offset;
1149       oopDesc* raw_oop = (oopDesc*)buffered_addr;
1150       size_t size = archive_object_size(raw_oop);
1151 
1152       intptr_t target_location = (intptr_t)buffered_offset;
1153       uint32_t narrow_location = checked_cast<uint32_t>(dfs_index);
1154       Klass* klass = raw_oop->klass();
1155 
1156       address requested_addr = (address)buffered_offset;
1157 
1158       return { buffered_addr,
1159                requested_addr,
1160                target_location,
1161                narrow_location,
1162                raw_oop,
1163                klass,
1164                size,
1165                false };
1166     }
1167 
1168     bool has_next() override {
1169       return _next <= _num_archived_objects;
1170     }
1171 
1172     AOTMapLogger::OopData next() override {
1173       _current = _next;
1174       AOTMapLogger::OopData result = capture(_current);
1175       _next = _current + 1;
1176       return result;
1177     }
1178 
1179     AOTMapLogger::OopData obj_at(narrowOop* addr) override {
1180       int dfs_index = (int)(*addr);
1181       if (dfs_index == 0) {
1182         return null_data();
1183       } else {
1184         return capture(dfs_index);
1185       }
1186     }
1187 
1188     AOTMapLogger::OopData obj_at(oop* addr) override {
1189       int dfs_index = (int)cast_from_oop<uintptr_t>(*addr);
1190       if (dfs_index == 0) {
1191         return null_data();
1192       } else {
1193         return capture(dfs_index);
1194       }
1195     }
1196 
1197     GrowableArrayCHeap<AOTMapLogger::OopData, mtClass>* roots() override {
1198       GrowableArrayCHeap<AOTMapLogger::OopData, mtClass>* result = new GrowableArrayCHeap<AOTMapLogger::OopData, mtClass>();
1199 
1200       for (int i = 0; i < _num_roots; ++i) {
1201         int object_index = object_index_for_root_index(i);
1202         result->append(capture(object_index));
1203       }
1204 
1205       return result;
1206     }
1207   };
1208 
1209   assert(_is_in_use, "printing before initializing?");
1210 
1211   return new StreamedLoaderOopIterator(buffer_start, (int)info->streamed_heap()->num_archived_objects());
1212 }
1213 
1214 #endif // INCLUDE_CDS_JAVA_HEAP