1 /*
   2  * Copyright (c) 2012, 2018, 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 "precompiled.hpp"
  26 #include "jvm.h"
  27 #include "classfile/classListParser.hpp"
  28 #include "classfile/classLoaderExt.hpp"
  29 #include "classfile/dictionary.hpp"
  30 #include "classfile/loaderConstraints.hpp"
  31 #include "classfile/placeholders.hpp"
  32 #include "classfile/symbolTable.hpp"
  33 #include "classfile/stringTable.hpp"
  34 #include "classfile/systemDictionary.hpp"
  35 #include "classfile/systemDictionaryShared.hpp"
  36 #include "code/codeCache.hpp"
  37 #include "interpreter/bytecodeStream.hpp"
  38 #include "interpreter/bytecodes.hpp"
  39 #include "logging/log.hpp"
  40 #include "logging/logMessage.hpp"
  41 #include "memory/filemap.hpp"
  42 #include "memory/heapShared.hpp"
  43 #include "memory/metaspace.hpp"
  44 #include "memory/metaspaceClosure.hpp"
  45 #include "memory/metaspaceShared.hpp"
  46 #include "memory/resourceArea.hpp"
  47 #include "oops/compressedOops.inline.hpp"
  48 #include "oops/instanceClassLoaderKlass.hpp"
  49 #include "oops/instanceMirrorKlass.hpp"
  50 #include "oops/instanceRefKlass.hpp"
  51 #include "oops/objArrayKlass.hpp"
  52 #include "oops/objArrayOop.hpp"
  53 #include "oops/oop.inline.hpp"
  54 #include "oops/typeArrayKlass.hpp"
  55 #include "prims/jvmtiRedefineClasses.hpp"
  56 #include "runtime/handles.inline.hpp"
  57 #include "runtime/os.hpp"
  58 #include "runtime/safepointVerifiers.hpp"
  59 #include "runtime/signature.hpp"
  60 #include "runtime/timerTrace.hpp"
  61 #include "runtime/vmThread.hpp"
  62 #include "runtime/vm_operations.hpp"
  63 #include "utilities/align.hpp"
  64 #include "utilities/defaultStream.hpp"
  65 #include "utilities/hashtable.inline.hpp"
  66 #if INCLUDE_G1GC
  67 #include "gc/g1/g1Allocator.inline.hpp"
  68 #include "gc/g1/g1CollectedHeap.hpp"
  69 #endif
  70 
  71 ReservedSpace MetaspaceShared::_shared_rs;
  72 VirtualSpace MetaspaceShared::_shared_vs;
  73 MetaspaceSharedStats MetaspaceShared::_stats;
  74 bool MetaspaceShared::_has_error_classes;
  75 bool MetaspaceShared::_archive_loading_failed = false;
  76 bool MetaspaceShared::_remapped_readwrite = false;
  77 bool MetaspaceShared::_open_archive_heap_region_mapped = false;
  78 address MetaspaceShared::_cds_i2i_entry_code_buffers = NULL;
  79 size_t MetaspaceShared::_cds_i2i_entry_code_buffers_size = 0;
  80 size_t MetaspaceShared::_core_spaces_size = 0;
  81 
  82 // The CDS archive is divided into the following regions:
  83 //     mc  - misc code (the method entry trampolines)
  84 //     rw  - read-write metadata
  85 //     ro  - read-only metadata and read-only tables
  86 //     md  - misc data (the c++ vtables)
  87 //     od  - optional data (original class files)
  88 //
  89 //     s0  - shared strings(closed archive heap space) #0
  90 //     s1  - shared strings(closed archive heap space) #1 (may be empty)
  91 //     oa0 - open archive heap space #0
  92 //     oa1 - open archive heap space #1 (may be empty)
  93 //
  94 // The mc, rw, ro, md and od regions are linearly allocated, starting from
  95 // SharedBaseAddress, in the order of mc->rw->ro->md->od. The size of these 5 regions
  96 // are page-aligned, and there's no gap between any consecutive regions.
  97 //
  98 // These 5 regions are populated in the following steps:
  99 // [1] All classes are loaded in MetaspaceShared::preload_classes(). All metadata are
 100 //     temporarily allocated outside of the shared regions. Only the method entry
 101 //     trampolines are written into the mc region.
 102 // [2] ArchiveCompactor copies RW metadata into the rw region.
 103 // [3] ArchiveCompactor copies RO metadata into the ro region.
 104 // [4] SymbolTable, StringTable, SystemDictionary, and a few other read-only data
 105 //     are copied into the ro region as read-only tables.
 106 // [5] C++ vtables are copied into the md region.
 107 // [6] Original class files are copied into the od region.
 108 //
 109 // The s0/s1 and oa0/oa1 regions are populated inside MetaspaceShared::dump_java_heap_objects.
 110 // Their layout is independent of the other 5 regions.
 111 
 112 class DumpRegion {
 113 private:
 114   const char* _name;
 115   char* _base;
 116   char* _top;
 117   char* _end;
 118   bool _is_packed;
 119 
 120   char* expand_top_to(char* newtop) {
 121     assert(is_allocatable(), "must be initialized and not packed");
 122     assert(newtop >= _top, "must not grow backwards");
 123     if (newtop > _end) {
 124       MetaspaceShared::report_out_of_space(_name, newtop - _top);
 125       ShouldNotReachHere();
 126     }
 127     MetaspaceShared::commit_shared_space_to(newtop);
 128     _top = newtop;
 129     return _top;
 130   }
 131 
 132 public:
 133   DumpRegion(const char* name) : _name(name), _base(NULL), _top(NULL), _end(NULL), _is_packed(false) {}
 134 
 135   char* allocate(size_t num_bytes, size_t alignment=BytesPerWord) {
 136     char* p = (char*)align_up(_top, alignment);
 137     char* newtop = p + align_up(num_bytes, alignment);
 138     expand_top_to(newtop);
 139     memset(p, 0, newtop - p);
 140     return p;
 141   }
 142 
 143   void append_intptr_t(intptr_t n) {
 144     assert(is_aligned(_top, sizeof(intptr_t)), "bad alignment");
 145     intptr_t *p = (intptr_t*)_top;
 146     char* newtop = _top + sizeof(intptr_t);
 147     expand_top_to(newtop);
 148     *p = n;
 149   }
 150 
 151   char* base()      const { return _base;        }
 152   char* top()       const { return _top;         }
 153   char* end()       const { return _end;         }
 154   size_t reserved() const { return _end - _base; }
 155   size_t used()     const { return _top - _base; }
 156   bool is_packed()  const { return _is_packed;   }
 157   bool is_allocatable() const {
 158     return !is_packed() && _base != NULL;
 159   }
 160 
 161   void print(size_t total_bytes) const {
 162     tty->print_cr("%-3s space: " SIZE_FORMAT_W(9) " [ %4.1f%% of total] out of " SIZE_FORMAT_W(9) " bytes [%5.1f%% used] at " INTPTR_FORMAT,
 163                   _name, used(), percent_of(used(), total_bytes), reserved(), percent_of(used(), reserved()), p2i(_base));
 164   }
 165   void print_out_of_space_msg(const char* failing_region, size_t needed_bytes) {
 166     tty->print("[%-8s] " PTR_FORMAT " - " PTR_FORMAT " capacity =%9d, allocated =%9d",
 167                _name, p2i(_base), p2i(_top), int(_end - _base), int(_top - _base));
 168     if (strcmp(_name, failing_region) == 0) {
 169       tty->print_cr(" required = %d", int(needed_bytes));
 170     } else {
 171       tty->cr();
 172     }
 173   }
 174 
 175   void init(const ReservedSpace* rs) {
 176     _base = _top = rs->base();
 177     _end = rs->end();
 178   }
 179   void init(char* b, char* t, char* e) {
 180     _base = b;
 181     _top = t;
 182     _end = e;
 183   }
 184 
 185   void pack(DumpRegion* next = NULL) {
 186     assert(!is_packed(), "sanity");
 187     _end = (char*)align_up(_top, Metaspace::reserve_alignment());
 188     _is_packed = true;
 189     if (next != NULL) {
 190       next->_base = next->_top = this->_end;
 191       next->_end = MetaspaceShared::shared_rs()->end();
 192     }
 193   }
 194   bool contains(char* p) {
 195     return base() <= p && p < top();
 196   }
 197 };
 198 
 199 
 200 DumpRegion _mc_region("mc"), _ro_region("ro"), _rw_region("rw"), _md_region("md"), _od_region("od");
 201 size_t _total_string_region_size = 0, _total_open_archive_region_size = 0;
 202 
 203 char* MetaspaceShared::misc_code_space_alloc(size_t num_bytes) {
 204   return _mc_region.allocate(num_bytes);
 205 }
 206 
 207 char* MetaspaceShared::read_only_space_alloc(size_t num_bytes) {
 208   return _ro_region.allocate(num_bytes);
 209 }
 210 
 211 char* MetaspaceShared::read_only_space_top() {
 212   return _ro_region.top();
 213 }
 214 
 215 void MetaspaceShared::initialize_runtime_shared_and_meta_spaces() {
 216   assert(UseSharedSpaces, "Must be called when UseSharedSpaces is enabled");
 217 
 218   // If using shared space, open the file that contains the shared space
 219   // and map in the memory before initializing the rest of metaspace (so
 220   // the addresses don't conflict)
 221   address cds_address = NULL;
 222   FileMapInfo* mapinfo = new FileMapInfo();
 223 
 224   // Open the shared archive file, read and validate the header. If
 225   // initialization fails, shared spaces [UseSharedSpaces] are
 226   // disabled and the file is closed.
 227   // Map in spaces now also
 228   if (mapinfo->initialize() && map_shared_spaces(mapinfo)) {
 229     size_t cds_total = core_spaces_size();
 230     cds_address = (address)mapinfo->header()->region_addr(0);
 231 #ifdef _LP64
 232     if (Metaspace::using_class_space()) {
 233       char* cds_end = (char*)(cds_address + cds_total);
 234       cds_end = (char *)align_up(cds_end, Metaspace::reserve_alignment());
 235       // If UseCompressedClassPointers is set then allocate the metaspace area
 236       // above the heap and above the CDS area (if it exists).
 237       Metaspace::allocate_metaspace_compressed_klass_ptrs(cds_end, cds_address);
 238       // map_heap_regions() compares the current narrow oop and klass encodings
 239       // with the archived ones, so it must be done after all encodings are determined.
 240       mapinfo->map_heap_regions();
 241     }
 242     Universe::set_narrow_klass_range(CompressedClassSpaceSize);
 243 #endif // _LP64
 244   } else {
 245     assert(!mapinfo->is_open() && !UseSharedSpaces,
 246            "archive file not closed or shared spaces not disabled.");
 247   }
 248 }
 249 
 250 void MetaspaceShared::initialize_dumptime_shared_and_meta_spaces() {
 251   assert(DumpSharedSpaces, "should be called for dump time only");
 252   const size_t reserve_alignment = Metaspace::reserve_alignment();
 253   bool large_pages = false; // No large pages when dumping the CDS archive.
 254   char* shared_base = (char*)align_up((char*)SharedBaseAddress, reserve_alignment);
 255 
 256 #ifdef _LP64
 257   // On 64-bit VM, the heap and class space layout will be the same as if
 258   // you're running in -Xshare:on mode:
 259   //
 260   //                              +-- SharedBaseAddress (default = 0x800000000)
 261   //                              v
 262   // +-..---------+---------+ ... +----+----+----+----+----+---------------+
 263   // |    Heap    | Archive |     | MC | RW | RO | MD | OD | class space   |
 264   // +-..---------+---------+ ... +----+----+----+----+----+---------------+
 265   // |<--   MaxHeapSize  -->|     |<-- UnscaledClassSpaceMax = 4GB ------->|
 266   //
 267   const uint64_t UnscaledClassSpaceMax = (uint64_t(max_juint) + 1);
 268   const size_t cds_total = align_down(UnscaledClassSpaceMax, reserve_alignment);
 269 #else
 270   // We don't support archives larger than 256MB on 32-bit due to limited virtual address space.
 271   size_t cds_total = align_down(256*M, reserve_alignment);
 272 #endif
 273 
 274   // First try to reserve the space at the specified SharedBaseAddress.
 275   _shared_rs = ReservedSpace(cds_total, reserve_alignment, large_pages, shared_base);
 276   if (_shared_rs.is_reserved()) {
 277     assert(shared_base == 0 || _shared_rs.base() == shared_base, "should match");
 278   } else {
 279     // Get a mmap region anywhere if the SharedBaseAddress fails.
 280     _shared_rs = ReservedSpace(cds_total, reserve_alignment, large_pages);
 281   }
 282   if (!_shared_rs.is_reserved()) {
 283     vm_exit_during_initialization("Unable to reserve memory for shared space",
 284                                   err_msg(SIZE_FORMAT " bytes.", cds_total));
 285   }
 286 
 287 #ifdef _LP64
 288   // During dump time, we allocate 4GB (UnscaledClassSpaceMax) of space and split it up:
 289   // + The upper 1 GB is used as the "temporary compressed class space" -- preload_classes()
 290   //   will store Klasses into this space.
 291   // + The lower 3 GB is used for the archive -- when preload_classes() is done,
 292   //   ArchiveCompactor will copy the class metadata into this space, first the RW parts,
 293   //   then the RO parts.
 294 
 295   assert(UseCompressedOops && UseCompressedClassPointers,
 296       "UseCompressedOops and UseCompressedClassPointers must be set");
 297 
 298   size_t max_archive_size = align_down(cds_total * 3 / 4, reserve_alignment);
 299   ReservedSpace tmp_class_space = _shared_rs.last_part(max_archive_size);
 300   CompressedClassSpaceSize = align_down(tmp_class_space.size(), reserve_alignment);
 301   _shared_rs = _shared_rs.first_part(max_archive_size);
 302 
 303   // Set up compress class pointers.
 304   Universe::set_narrow_klass_base((address)_shared_rs.base());
 305   // Set narrow_klass_shift to be LogKlassAlignmentInBytes. This is consistent
 306   // with AOT.
 307   Universe::set_narrow_klass_shift(LogKlassAlignmentInBytes);
 308   // Set the range of klass addresses to 4GB.
 309   Universe::set_narrow_klass_range(cds_total);
 310 
 311   Metaspace::initialize_class_space(tmp_class_space);
 312   tty->print_cr("narrow_klass_base = " PTR_FORMAT ", narrow_klass_shift = %d",
 313                 p2i(Universe::narrow_klass_base()), Universe::narrow_klass_shift());
 314 
 315   tty->print_cr("Allocated temporary class space: " SIZE_FORMAT " bytes at " PTR_FORMAT,
 316                 CompressedClassSpaceSize, p2i(tmp_class_space.base()));
 317 #endif
 318 
 319   // Start with 0 committed bytes. The memory will be committed as needed by
 320   // MetaspaceShared::commit_shared_space_to().
 321   if (!_shared_vs.initialize(_shared_rs, 0)) {
 322     vm_exit_during_initialization("Unable to allocate memory for shared space");
 323   }
 324 
 325   _mc_region.init(&_shared_rs);
 326   tty->print_cr("Allocated shared space: " SIZE_FORMAT " bytes at " PTR_FORMAT,
 327                 _shared_rs.size(), p2i(_shared_rs.base()));
 328 }
 329 
 330 // Called by universe_post_init()
 331 void MetaspaceShared::post_initialize(TRAPS) {
 332   if (UseSharedSpaces) {
 333     int size = FileMapInfo::get_number_of_shared_paths();
 334     if (size > 0) {
 335       SystemDictionaryShared::allocate_shared_data_arrays(size, THREAD);
 336       FileMapInfo::FileMapHeader* header = FileMapInfo::current_info()->header();
 337       ClassLoaderExt::init_paths_start_index(header->_app_class_paths_start_index);
 338       ClassLoaderExt::init_app_module_paths_start_index(header->_app_module_paths_start_index);
 339     }
 340   }
 341 
 342   if (DumpSharedSpaces) {
 343     if (SharedArchiveConfigFile) {
 344       read_extra_data(SharedArchiveConfigFile, THREAD);
 345     }
 346   }
 347 }
 348 
 349 void MetaspaceShared::read_extra_data(const char* filename, TRAPS) {
 350   HashtableTextDump reader(filename);
 351   reader.check_version("VERSION: 1.0");
 352 
 353   while (reader.remain() > 0) {
 354     int utf8_length;
 355     int prefix_type = reader.scan_prefix(&utf8_length);
 356     ResourceMark rm(THREAD);
 357     char* utf8_buffer = NEW_RESOURCE_ARRAY(char, utf8_length);
 358     reader.get_utf8(utf8_buffer, utf8_length);
 359 
 360     if (prefix_type == HashtableTextDump::SymbolPrefix) {
 361       SymbolTable::new_symbol(utf8_buffer, utf8_length, THREAD);
 362     } else{
 363       assert(prefix_type == HashtableTextDump::StringPrefix, "Sanity");
 364       utf8_buffer[utf8_length] = '\0';
 365       oop s = StringTable::intern(utf8_buffer, THREAD);
 366     }
 367   }
 368 }
 369 
 370 void MetaspaceShared::commit_shared_space_to(char* newtop) {
 371   assert(DumpSharedSpaces, "dump-time only");
 372   char* base = _shared_rs.base();
 373   size_t need_committed_size = newtop - base;
 374   size_t has_committed_size = _shared_vs.committed_size();
 375   if (need_committed_size < has_committed_size) {
 376     return;
 377   }
 378 
 379   size_t min_bytes = need_committed_size - has_committed_size;
 380   size_t preferred_bytes = 1 * M;
 381   size_t uncommitted = _shared_vs.reserved_size() - has_committed_size;
 382 
 383   size_t commit = MAX2(min_bytes, preferred_bytes);
 384   assert(commit <= uncommitted, "sanity");
 385 
 386   bool result = _shared_vs.expand_by(commit, false);
 387   if (!result) {
 388     vm_exit_during_initialization(err_msg("Failed to expand shared space to " SIZE_FORMAT " bytes",
 389                                           need_committed_size));
 390   }
 391 
 392   log_info(cds)("Expanding shared spaces by " SIZE_FORMAT_W(7) " bytes [total " SIZE_FORMAT_W(9)  " bytes ending at %p]",
 393                 commit, _shared_vs.actual_committed_size(), _shared_vs.high());
 394 }
 395 
 396 // Read/write a data stream for restoring/preserving metadata pointers and
 397 // miscellaneous data from/to the shared archive file.
 398 
 399 void MetaspaceShared::serialize(SerializeClosure* soc) {
 400   int tag = 0;
 401   soc->do_tag(--tag);
 402 
 403   // Verify the sizes of various metadata in the system.
 404   soc->do_tag(sizeof(Method));
 405   soc->do_tag(sizeof(ConstMethod));
 406   soc->do_tag(arrayOopDesc::base_offset_in_bytes(T_BYTE));
 407   soc->do_tag(sizeof(ConstantPool));
 408   soc->do_tag(sizeof(ConstantPoolCache));
 409   soc->do_tag(objArrayOopDesc::base_offset_in_bytes());
 410   soc->do_tag(typeArrayOopDesc::base_offset_in_bytes(T_BYTE));
 411   soc->do_tag(sizeof(Symbol));
 412 
 413   // Dump/restore miscellaneous metadata.
 414   Universe::serialize(soc, true);
 415   soc->do_tag(--tag);
 416 
 417   // Dump/restore references to commonly used names and signatures.
 418   vmSymbols::serialize(soc);
 419   soc->do_tag(--tag);
 420 
 421   // Dump/restore the symbol and string tables
 422   SymbolTable::serialize(soc);
 423   StringTable::serialize(soc);
 424   soc->do_tag(--tag);
 425 
 426   serialize_well_known_classes(soc);
 427   soc->do_tag(--tag);
 428 
 429   soc->do_tag(666);
 430 }
 431 
 432 void MetaspaceShared::serialize_well_known_classes(SerializeClosure* soc) {
 433   java_lang_Class::serialize(soc);
 434   java_lang_String::serialize(soc);
 435   java_lang_System::serialize(soc);
 436   java_lang_ClassLoader::serialize(soc);
 437   java_lang_Throwable::serialize(soc);
 438   java_lang_Thread::serialize(soc);
 439   java_lang_ThreadGroup::serialize(soc);
 440   java_lang_AssertionStatusDirectives::serialize(soc);
 441   java_lang_module_Configuration::serialize(soc);
 442   java_lang_ref_SoftReference::serialize(soc);
 443   java_lang_invoke_MethodHandle::serialize(soc);
 444   java_lang_invoke_DirectMethodHandle::serialize(soc);
 445   java_lang_invoke_MemberName::serialize(soc);
 446   java_lang_invoke_ResolvedMethodName::serialize(soc);
 447   java_lang_invoke_LambdaForm::serialize(soc);
 448   java_lang_invoke_MethodType::serialize(soc);
 449   java_lang_invoke_CallSite::serialize(soc);
 450   java_lang_invoke_MethodHandleNatives_CallSiteContext::serialize(soc);
 451   java_security_AccessControlContext::serialize(soc);
 452   java_lang_reflect_AccessibleObject::serialize(soc);
 453   java_lang_reflect_Method::serialize(soc);
 454   java_lang_reflect_Constructor::serialize(soc);
 455   java_lang_reflect_Field::serialize(soc);
 456   java_nio_Buffer::serialize(soc);
 457   reflect_ConstantPool::serialize(soc);
 458   reflect_UnsafeStaticFieldAccessorImpl::serialize(soc);
 459   java_lang_reflect_Parameter::serialize(soc);
 460   java_lang_Module::serialize(soc);
 461   java_lang_StackTraceElement::serialize(soc);
 462   java_lang_StackFrameInfo::serialize(soc);
 463   java_lang_LiveStackFrameInfo::serialize(soc);
 464   java_util_concurrent_locks_AbstractOwnableSynchronizer::serialize(soc);
 465   java_util_ImmutableCollections_ListN::serialize(soc);
 466   java_util_ImmutableCollections_MapN::serialize(soc);
 467   java_util_ImmutableCollections_SetN::serialize(soc);
 468   jdk_internal_module_ArchivedModuleGraph::serialize(soc);
 469 }
 470 
 471 address MetaspaceShared::cds_i2i_entry_code_buffers(size_t total_size) {
 472   if (DumpSharedSpaces) {
 473     if (_cds_i2i_entry_code_buffers == NULL) {
 474       _cds_i2i_entry_code_buffers = (address)misc_code_space_alloc(total_size);
 475       _cds_i2i_entry_code_buffers_size = total_size;
 476     }
 477   } else if (UseSharedSpaces) {
 478     assert(_cds_i2i_entry_code_buffers != NULL, "must already been initialized");
 479   } else {
 480     return NULL;
 481   }
 482 
 483   assert(_cds_i2i_entry_code_buffers_size == total_size, "must not change");
 484   return _cds_i2i_entry_code_buffers;
 485 }
 486 
 487 // CDS code for dumping shared archive.
 488 
 489 // Global object for holding classes that have been loaded.  Since this
 490 // is run at a safepoint just before exit, this is the entire set of classes.
 491 static GrowableArray<Klass*>* _global_klass_objects;
 492 
 493 static void collect_array_classes(Klass* k) {
 494   _global_klass_objects->append_if_missing(k);
 495   if (k->is_array_klass()) {
 496     // Add in the array classes too
 497     ArrayKlass* ak = ArrayKlass::cast(k);
 498     Klass* h = ak->higher_dimension();
 499     if (h != NULL) {
 500       h->array_klasses_do(collect_array_classes);
 501     }
 502   }
 503 }
 504 
 505 class CollectClassesClosure : public KlassClosure {
 506   void do_klass(Klass* k) {
 507     if (!(k->is_instance_klass() && InstanceKlass::cast(k)->is_in_error_state())) {
 508       if (k->is_instance_klass() && InstanceKlass::cast(k)->signers() != NULL) {
 509         // Mark any class with signers and don't add to the _global_klass_objects
 510         k->set_has_signer_and_not_archived();
 511       } else {
 512         _global_klass_objects->append_if_missing(k);
 513       }
 514     }
 515     if (k->is_array_klass()) {
 516       // Add in the array classes too
 517       ArrayKlass* ak = ArrayKlass::cast(k);
 518       Klass* h = ak->higher_dimension();
 519       if (h != NULL) {
 520         h->array_klasses_do(collect_array_classes);
 521       }
 522     }
 523   }
 524 };
 525 
 526 static void remove_unshareable_in_classes() {
 527   for (int i = 0; i < _global_klass_objects->length(); i++) {
 528     Klass* k = _global_klass_objects->at(i);
 529     if (!k->is_objArray_klass()) {
 530       // InstanceKlass and TypeArrayKlass will in turn call remove_unshareable_info
 531       // on their array classes.
 532       assert(k->is_instance_klass() || k->is_typeArray_klass(), "must be");
 533       k->remove_unshareable_info();
 534     }
 535   }
 536 }
 537 
 538 static void remove_java_mirror_in_classes() {
 539   for (int i = 0; i < _global_klass_objects->length(); i++) {
 540     Klass* k = _global_klass_objects->at(i);
 541     if (!k->is_objArray_klass()) {
 542       // InstanceKlass and TypeArrayKlass will in turn call remove_unshareable_info
 543       // on their array classes.
 544       assert(k->is_instance_klass() || k->is_typeArray_klass(), "must be");
 545       k->remove_java_mirror();
 546     }
 547   }
 548 }
 549 
 550 static void clear_basic_type_mirrors() {
 551   assert(!MetaspaceShared::is_heap_object_archiving_allowed(), "Sanity");
 552   Universe::set_int_mirror(NULL);
 553   Universe::set_float_mirror(NULL);
 554   Universe::set_double_mirror(NULL);
 555   Universe::set_byte_mirror(NULL);
 556   Universe::set_bool_mirror(NULL);
 557   Universe::set_char_mirror(NULL);
 558   Universe::set_long_mirror(NULL);
 559   Universe::set_short_mirror(NULL);
 560   Universe::set_void_mirror(NULL);
 561 }
 562 
 563 static void rewrite_nofast_bytecode(Method* method) {
 564   BytecodeStream bcs(method);
 565   while (!bcs.is_last_bytecode()) {
 566     Bytecodes::Code opcode = bcs.next();
 567     switch (opcode) {
 568     case Bytecodes::_getfield:      *bcs.bcp() = Bytecodes::_nofast_getfield;      break;
 569     case Bytecodes::_putfield:      *bcs.bcp() = Bytecodes::_nofast_putfield;      break;
 570     case Bytecodes::_aload_0:       *bcs.bcp() = Bytecodes::_nofast_aload_0;       break;
 571     case Bytecodes::_iload: {
 572       if (!bcs.is_wide()) {
 573         *bcs.bcp() = Bytecodes::_nofast_iload;
 574       }
 575       break;
 576     }
 577     default: break;
 578     }
 579   }
 580 }
 581 
 582 // Walk all methods in the class list to ensure that they won't be modified at
 583 // run time. This includes:
 584 // [1] Rewrite all bytecodes as needed, so that the ConstMethod* will not be modified
 585 //     at run time by RewriteBytecodes/RewriteFrequentPairs
 586 // [2] Assign a fingerprint, so one doesn't need to be assigned at run-time.
 587 static void rewrite_nofast_bytecodes_and_calculate_fingerprints() {
 588   for (int i = 0; i < _global_klass_objects->length(); i++) {
 589     Klass* k = _global_klass_objects->at(i);
 590     if (k->is_instance_klass()) {
 591       InstanceKlass* ik = InstanceKlass::cast(k);
 592       for (int i = 0; i < ik->methods()->length(); i++) {
 593         Method* m = ik->methods()->at(i);
 594         rewrite_nofast_bytecode(m);
 595         Fingerprinter fp(m);
 596         // The side effect of this call sets method's fingerprint field.
 597         fp.fingerprint();
 598       }
 599     }
 600   }
 601 }
 602 
 603 static void relocate_cached_class_file() {
 604   for (int i = 0; i < _global_klass_objects->length(); i++) {
 605     Klass* k = _global_klass_objects->at(i);
 606     if (k->is_instance_klass()) {
 607       InstanceKlass* ik = InstanceKlass::cast(k);
 608       JvmtiCachedClassFileData* p = ik->get_archived_class_data();
 609       if (p != NULL) {
 610         int size = offset_of(JvmtiCachedClassFileData, data) + p->length;
 611         JvmtiCachedClassFileData* q = (JvmtiCachedClassFileData*)_od_region.allocate(size);
 612         q->length = p->length;
 613         memcpy(q->data, p->data, p->length);
 614         ik->set_archived_class_data(q);
 615       }
 616     }
 617   }
 618 }
 619 
 620 NOT_PRODUCT(
 621 static void assert_not_anonymous_class(InstanceKlass* k) {
 622   assert(!(k->is_anonymous()), "cannot archive anonymous classes");
 623 }
 624 
 625 // Anonymous classes are not stored inside any dictionaries. They are created by
 626 // SystemDictionary::parse_stream() with a non-null host_klass.
 627 static void assert_no_anonymoys_classes_in_dictionaries() {
 628   ClassLoaderDataGraph::dictionary_classes_do(assert_not_anonymous_class);
 629 })
 630 
 631 // Objects of the Metadata types (such as Klass and ConstantPool) have C++ vtables.
 632 // (In GCC this is the field <Type>::_vptr, i.e., first word in the object.)
 633 //
 634 // Addresses of the vtables and the methods may be different across JVM runs,
 635 // if libjvm.so is dynamically loaded at a different base address.
 636 //
 637 // To ensure that the Metadata objects in the CDS archive always have the correct vtable:
 638 //
 639 // + at dump time:  we redirect the _vptr to point to our own vtables inside
 640 //                  the CDS image
 641 // + at run time:   we clone the actual contents of the vtables from libjvm.so
 642 //                  into our own tables.
 643 
 644 // Currently, the archive contain ONLY the following types of objects that have C++ vtables.
 645 #define CPP_VTABLE_PATCH_TYPES_DO(f) \
 646   f(ConstantPool) \
 647   f(InstanceKlass) \
 648   f(InstanceClassLoaderKlass) \
 649   f(InstanceMirrorKlass) \
 650   f(InstanceRefKlass) \
 651   f(Method) \
 652   f(ObjArrayKlass) \
 653   f(TypeArrayKlass)
 654 
 655 class CppVtableInfo {
 656   intptr_t _vtable_size;
 657   intptr_t _cloned_vtable[1];
 658 public:
 659   static int num_slots(int vtable_size) {
 660     return 1 + vtable_size; // Need to add the space occupied by _vtable_size;
 661   }
 662   int vtable_size()           { return int(uintx(_vtable_size)); }
 663   void set_vtable_size(int n) { _vtable_size = intptr_t(n); }
 664   intptr_t* cloned_vtable()   { return &_cloned_vtable[0]; }
 665   void zero()                 { memset(_cloned_vtable, 0, sizeof(intptr_t) * vtable_size()); }
 666   // Returns the address of the next CppVtableInfo that can be placed immediately after this CppVtableInfo
 667   static size_t byte_size(int vtable_size) {
 668     CppVtableInfo i;
 669     return pointer_delta(&i._cloned_vtable[vtable_size], &i, sizeof(u1));
 670   }
 671 };
 672 
 673 template <class T> class CppVtableCloner : public T {
 674   static intptr_t* vtable_of(Metadata& m) {
 675     return *((intptr_t**)&m);
 676   }
 677   static CppVtableInfo* _info;
 678 
 679   static int get_vtable_length(const char* name);
 680 
 681 public:
 682   // Allocate and initialize the C++ vtable, starting from top, but do not go past end.
 683   static intptr_t* allocate(const char* name);
 684 
 685   // Clone the vtable to ...
 686   static intptr_t* clone_vtable(const char* name, CppVtableInfo* info);
 687 
 688   static void zero_vtable_clone() {
 689     assert(DumpSharedSpaces, "dump-time only");
 690     _info->zero();
 691   }
 692 
 693   // Switch the vtable pointer to point to the cloned vtable.
 694   static void patch(Metadata* obj) {
 695     assert(DumpSharedSpaces, "dump-time only");
 696     *(void**)obj = (void*)(_info->cloned_vtable());
 697   }
 698 
 699   static bool is_valid_shared_object(const T* obj) {
 700     intptr_t* vptr = *(intptr_t**)obj;
 701     return vptr == _info->cloned_vtable();
 702   }
 703 };
 704 
 705 template <class T> CppVtableInfo* CppVtableCloner<T>::_info = NULL;
 706 
 707 template <class T>
 708 intptr_t* CppVtableCloner<T>::allocate(const char* name) {
 709   assert(is_aligned(_md_region.top(), sizeof(intptr_t)), "bad alignment");
 710   int n = get_vtable_length(name);
 711   _info = (CppVtableInfo*)_md_region.allocate(CppVtableInfo::byte_size(n), sizeof(intptr_t));
 712   _info->set_vtable_size(n);
 713 
 714   intptr_t* p = clone_vtable(name, _info);
 715   assert((char*)p == _md_region.top(), "must be");
 716 
 717   return p;
 718 }
 719 
 720 template <class T>
 721 intptr_t* CppVtableCloner<T>::clone_vtable(const char* name, CppVtableInfo* info) {
 722   if (!DumpSharedSpaces) {
 723     assert(_info == 0, "_info is initialized only at dump time");
 724     _info = info; // Remember it -- it will be used by MetaspaceShared::is_valid_shared_method()
 725   }
 726   T tmp; // Allocate temporary dummy metadata object to get to the original vtable.
 727   int n = info->vtable_size();
 728   intptr_t* srcvtable = vtable_of(tmp);
 729   intptr_t* dstvtable = info->cloned_vtable();
 730 
 731   // We already checked (and, if necessary, adjusted n) when the vtables were allocated, so we are
 732   // safe to do memcpy.
 733   log_debug(cds, vtables)("Copying %3d vtable entries for %s", n, name);
 734   memcpy(dstvtable, srcvtable, sizeof(intptr_t) * n);
 735   return dstvtable + n;
 736 }
 737 
 738 // To determine the size of the vtable for each type, we use the following
 739 // trick by declaring 2 subclasses:
 740 //
 741 //   class CppVtableTesterA: public InstanceKlass {virtual int   last_virtual_method() {return 1;}    };
 742 //   class CppVtableTesterB: public InstanceKlass {virtual void* last_virtual_method() {return NULL}; };
 743 //
 744 // CppVtableTesterA and CppVtableTesterB's vtables have the following properties:
 745 // - Their size (N+1) is exactly one more than the size of InstanceKlass's vtable (N)
 746 // - The first N entries have are exactly the same as in InstanceKlass's vtable.
 747 // - Their last entry is different.
 748 //
 749 // So to determine the value of N, we just walk CppVtableTesterA and CppVtableTesterB's tables
 750 // and find the first entry that's different.
 751 //
 752 // This works on all C++ compilers supported by Oracle, but you may need to tweak it for more
 753 // esoteric compilers.
 754 
 755 template <class T> class CppVtableTesterB: public T {
 756 public:
 757   virtual int last_virtual_method() {return 1;}
 758 };
 759 
 760 template <class T> class CppVtableTesterA : public T {
 761 public:
 762   virtual void* last_virtual_method() {
 763     // Make this different than CppVtableTesterB::last_virtual_method so the C++
 764     // compiler/linker won't alias the two functions.
 765     return NULL;
 766   }
 767 };
 768 
 769 template <class T>
 770 int CppVtableCloner<T>::get_vtable_length(const char* name) {
 771   CppVtableTesterA<T> a;
 772   CppVtableTesterB<T> b;
 773 
 774   intptr_t* avtable = vtable_of(a);
 775   intptr_t* bvtable = vtable_of(b);
 776 
 777   // Start at slot 1, because slot 0 may be RTTI (on Solaris/Sparc)
 778   int vtable_len = 1;
 779   for (; ; vtable_len++) {
 780     if (avtable[vtable_len] != bvtable[vtable_len]) {
 781       break;
 782     }
 783   }
 784   log_debug(cds, vtables)("Found   %3d vtable entries for %s", vtable_len, name);
 785 
 786   return vtable_len;
 787 }
 788 
 789 #define ALLOC_CPP_VTABLE_CLONE(c) \
 790   CppVtableCloner<c>::allocate(#c);
 791 
 792 #define CLONE_CPP_VTABLE(c) \
 793   p = CppVtableCloner<c>::clone_vtable(#c, (CppVtableInfo*)p);
 794 
 795 #define ZERO_CPP_VTABLE(c) \
 796  CppVtableCloner<c>::zero_vtable_clone();
 797 
 798 // This can be called at both dump time and run time.
 799 intptr_t* MetaspaceShared::clone_cpp_vtables(intptr_t* p) {
 800   assert(DumpSharedSpaces || UseSharedSpaces, "sanity");
 801   CPP_VTABLE_PATCH_TYPES_DO(CLONE_CPP_VTABLE);
 802   return p;
 803 }
 804 
 805 void MetaspaceShared::zero_cpp_vtable_clones_for_writing() {
 806   assert(DumpSharedSpaces, "dump-time only");
 807   CPP_VTABLE_PATCH_TYPES_DO(ZERO_CPP_VTABLE);
 808 }
 809 
 810 // Allocate and initialize the C++ vtables, starting from top, but do not go past end.
 811 void MetaspaceShared::allocate_cpp_vtable_clones() {
 812   assert(DumpSharedSpaces, "dump-time only");
 813   // Layout (each slot is a intptr_t):
 814   //   [number of slots in the first vtable = n1]
 815   //   [ <n1> slots for the first vtable]
 816   //   [number of slots in the first second = n2]
 817   //   [ <n2> slots for the second vtable]
 818   //   ...
 819   // The order of the vtables is the same as the CPP_VTAB_PATCH_TYPES_DO macro.
 820   CPP_VTABLE_PATCH_TYPES_DO(ALLOC_CPP_VTABLE_CLONE);
 821 }
 822 
 823 // Switch the vtable pointer to point to the cloned vtable. We assume the
 824 // vtable pointer is in first slot in object.
 825 void MetaspaceShared::patch_cpp_vtable_pointers() {
 826   int n = _global_klass_objects->length();
 827   for (int i = 0; i < n; i++) {
 828     Klass* obj = _global_klass_objects->at(i);
 829     if (obj->is_instance_klass()) {
 830       InstanceKlass* ik = InstanceKlass::cast(obj);
 831       if (ik->is_class_loader_instance_klass()) {
 832         CppVtableCloner<InstanceClassLoaderKlass>::patch(ik);
 833       } else if (ik->is_reference_instance_klass()) {
 834         CppVtableCloner<InstanceRefKlass>::patch(ik);
 835       } else if (ik->is_mirror_instance_klass()) {
 836         CppVtableCloner<InstanceMirrorKlass>::patch(ik);
 837       } else {
 838         CppVtableCloner<InstanceKlass>::patch(ik);
 839       }
 840       ConstantPool* cp = ik->constants();
 841       CppVtableCloner<ConstantPool>::patch(cp);
 842       for (int j = 0; j < ik->methods()->length(); j++) {
 843         Method* m = ik->methods()->at(j);
 844         CppVtableCloner<Method>::patch(m);
 845         assert(CppVtableCloner<Method>::is_valid_shared_object(m), "must be");
 846       }
 847     } else if (obj->is_objArray_klass()) {
 848       CppVtableCloner<ObjArrayKlass>::patch(obj);
 849     } else {
 850       assert(obj->is_typeArray_klass(), "sanity");
 851       CppVtableCloner<TypeArrayKlass>::patch(obj);
 852     }
 853   }
 854 }
 855 
 856 bool MetaspaceShared::is_valid_shared_method(const Method* m) {
 857   assert(is_in_shared_metaspace(m), "must be");
 858   return CppVtableCloner<Method>::is_valid_shared_object(m);
 859 }
 860 
 861 // Closure for serializing initialization data out to a data area to be
 862 // written to the shared file.
 863 
 864 class WriteClosure : public SerializeClosure {
 865 private:
 866   DumpRegion* _dump_region;
 867 
 868 public:
 869   WriteClosure(DumpRegion* r) {
 870     _dump_region = r;
 871   }
 872 
 873   void do_ptr(void** p) {
 874     _dump_region->append_intptr_t((intptr_t)*p);
 875   }
 876 
 877   void do_u4(u4* p) {
 878     void* ptr = (void*)(uintx(*p));
 879     do_ptr(&ptr);
 880   }
 881 
 882   void do_tag(int tag) {
 883     _dump_region->append_intptr_t((intptr_t)tag);
 884   }
 885 
 886   void do_oop(oop* o) {
 887     if (*o == NULL) {
 888       _dump_region->append_intptr_t(0);
 889     } else {
 890       assert(MetaspaceShared::is_heap_object_archiving_allowed(),
 891              "Archiving heap object is not allowed");
 892       _dump_region->append_intptr_t(
 893         (intptr_t)CompressedOops::encode_not_null(*o));
 894     }
 895   }
 896 
 897   void do_region(u_char* start, size_t size) {
 898     assert((intptr_t)start % sizeof(intptr_t) == 0, "bad alignment");
 899     assert(size % sizeof(intptr_t) == 0, "bad size");
 900     do_tag((int)size);
 901     while (size > 0) {
 902       _dump_region->append_intptr_t(*(intptr_t*)start);
 903       start += sizeof(intptr_t);
 904       size -= sizeof(intptr_t);
 905     }
 906   }
 907 
 908   bool reading() const { return false; }
 909 };
 910 
 911 // This is for dumping detailed statistics for the allocations
 912 // in the shared spaces.
 913 class DumpAllocStats : public ResourceObj {
 914 public:
 915 
 916   // Here's poor man's enum inheritance
 917 #define SHAREDSPACE_OBJ_TYPES_DO(f) \
 918   METASPACE_OBJ_TYPES_DO(f) \
 919   f(SymbolHashentry) \
 920   f(SymbolBucket) \
 921   f(StringHashentry) \
 922   f(StringBucket) \
 923   f(Other)
 924 
 925   enum Type {
 926     // Types are MetaspaceObj::ClassType, MetaspaceObj::SymbolType, etc
 927     SHAREDSPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_DECLARE)
 928     _number_of_types
 929   };
 930 
 931   static const char * type_name(Type type) {
 932     switch(type) {
 933     SHAREDSPACE_OBJ_TYPES_DO(METASPACE_OBJ_TYPE_NAME_CASE)
 934     default:
 935       ShouldNotReachHere();
 936       return NULL;
 937     }
 938   }
 939 
 940 public:
 941   enum { RO = 0, RW = 1 };
 942 
 943   int _counts[2][_number_of_types];
 944   int _bytes [2][_number_of_types];
 945 
 946   DumpAllocStats() {
 947     memset(_counts, 0, sizeof(_counts));
 948     memset(_bytes,  0, sizeof(_bytes));
 949   };
 950 
 951   void record(MetaspaceObj::Type type, int byte_size, bool read_only) {
 952     assert(int(type) >= 0 && type < MetaspaceObj::_number_of_types, "sanity");
 953     int which = (read_only) ? RO : RW;
 954     _counts[which][type] ++;
 955     _bytes [which][type] += byte_size;
 956   }
 957 
 958   void record_other_type(int byte_size, bool read_only) {
 959     int which = (read_only) ? RO : RW;
 960     _bytes [which][OtherType] += byte_size;
 961   }
 962   void print_stats(int ro_all, int rw_all, int mc_all, int md_all);
 963 };
 964 
 965 void DumpAllocStats::print_stats(int ro_all, int rw_all, int mc_all, int md_all) {
 966   // Calculate size of data that was not allocated by Metaspace::allocate()
 967   MetaspaceSharedStats *stats = MetaspaceShared::stats();
 968 
 969   // symbols
 970   _counts[RO][SymbolHashentryType] = stats->symbol.hashentry_count;
 971   _bytes [RO][SymbolHashentryType] = stats->symbol.hashentry_bytes;
 972 
 973   _counts[RO][SymbolBucketType] = stats->symbol.bucket_count;
 974   _bytes [RO][SymbolBucketType] = stats->symbol.bucket_bytes;
 975 
 976   // strings
 977   _counts[RO][StringHashentryType] = stats->string.hashentry_count;
 978   _bytes [RO][StringHashentryType] = stats->string.hashentry_bytes;
 979 
 980   _counts[RO][StringBucketType] = stats->string.bucket_count;
 981   _bytes [RO][StringBucketType] = stats->string.bucket_bytes;
 982 
 983   // TODO: count things like dictionary, vtable, etc
 984   _bytes[RW][OtherType] += mc_all + md_all;
 985   rw_all += mc_all + md_all; // mc/md are mapped Read/Write
 986 
 987   // prevent divide-by-zero
 988   if (ro_all < 1) {
 989     ro_all = 1;
 990   }
 991   if (rw_all < 1) {
 992     rw_all = 1;
 993   }
 994 
 995   int all_ro_count = 0;
 996   int all_ro_bytes = 0;
 997   int all_rw_count = 0;
 998   int all_rw_bytes = 0;
 999 
1000 // To make fmt_stats be a syntactic constant (for format warnings), use #define.
1001 #define fmt_stats "%-20s: %8d %10d %5.1f | %8d %10d %5.1f | %8d %10d %5.1f"
1002   const char *sep = "--------------------+---------------------------+---------------------------+--------------------------";
1003   const char *hdr = "                        ro_cnt   ro_bytes     % |   rw_cnt   rw_bytes     % |  all_cnt  all_bytes     %";
1004 
1005   LogMessage(cds) msg;
1006 
1007   msg.info("Detailed metadata info (excluding od/st regions; rw stats include md/mc regions):");
1008   msg.info("%s", hdr);
1009   msg.info("%s", sep);
1010   for (int type = 0; type < int(_number_of_types); type ++) {
1011     const char *name = type_name((Type)type);
1012     int ro_count = _counts[RO][type];
1013     int ro_bytes = _bytes [RO][type];
1014     int rw_count = _counts[RW][type];
1015     int rw_bytes = _bytes [RW][type];
1016     int count = ro_count + rw_count;
1017     int bytes = ro_bytes + rw_bytes;
1018 
1019     double ro_perc = percent_of(ro_bytes, ro_all);
1020     double rw_perc = percent_of(rw_bytes, rw_all);
1021     double perc    = percent_of(bytes, ro_all + rw_all);
1022 
1023     msg.info(fmt_stats, name,
1024                          ro_count, ro_bytes, ro_perc,
1025                          rw_count, rw_bytes, rw_perc,
1026                          count, bytes, perc);
1027 
1028     all_ro_count += ro_count;
1029     all_ro_bytes += ro_bytes;
1030     all_rw_count += rw_count;
1031     all_rw_bytes += rw_bytes;
1032   }
1033 
1034   int all_count = all_ro_count + all_rw_count;
1035   int all_bytes = all_ro_bytes + all_rw_bytes;
1036 
1037   double all_ro_perc = percent_of(all_ro_bytes, ro_all);
1038   double all_rw_perc = percent_of(all_rw_bytes, rw_all);
1039   double all_perc    = percent_of(all_bytes, ro_all + rw_all);
1040 
1041   msg.info("%s", sep);
1042   msg.info(fmt_stats, "Total",
1043                        all_ro_count, all_ro_bytes, all_ro_perc,
1044                        all_rw_count, all_rw_bytes, all_rw_perc,
1045                        all_count, all_bytes, all_perc);
1046 
1047   assert(all_ro_bytes == ro_all, "everything should have been counted");
1048   assert(all_rw_bytes == rw_all, "everything should have been counted");
1049 
1050 #undef fmt_stats
1051 }
1052 
1053 // Populate the shared space.
1054 
1055 class VM_PopulateDumpSharedSpace: public VM_Operation {
1056 private:
1057   GrowableArray<MemRegion> *_closed_archive_heap_regions;
1058   GrowableArray<MemRegion> *_open_archive_heap_regions;
1059 
1060   void dump_java_heap_objects() NOT_CDS_JAVA_HEAP_RETURN;
1061   void dump_symbols();
1062   char* dump_read_only_tables();
1063   void print_region_stats();
1064   void print_heap_region_stats(GrowableArray<MemRegion> *heap_mem,
1065                                const char *name, const size_t total_size);
1066 public:
1067 
1068   VMOp_Type type() const { return VMOp_PopulateDumpSharedSpace; }
1069   void doit();   // outline because gdb sucks
1070   static void write_region(FileMapInfo* mapinfo, int region, DumpRegion* space, bool read_only,  bool allow_exec);
1071   bool allow_nested_vm_operations() const { return true; }
1072 }; // class VM_PopulateDumpSharedSpace
1073 
1074 class SortedSymbolClosure: public SymbolClosure {
1075   GrowableArray<Symbol*> _symbols;
1076   virtual void do_symbol(Symbol** sym) {
1077     assert((*sym)->is_permanent(), "archived symbols must be permanent");
1078     _symbols.append(*sym);
1079   }
1080   static int compare_symbols_by_address(Symbol** a, Symbol** b) {
1081     if (a[0] < b[0]) {
1082       return -1;
1083     } else if (a[0] == b[0]) {
1084       return 0;
1085     } else {
1086       return 1;
1087     }
1088   }
1089 
1090 public:
1091   SortedSymbolClosure() {
1092     SymbolTable::symbols_do(this);
1093     _symbols.sort(compare_symbols_by_address);
1094   }
1095   GrowableArray<Symbol*>* get_sorted_symbols() {
1096     return &_symbols;
1097   }
1098 };
1099 
1100 // ArchiveCompactor --
1101 //
1102 // This class is the central piece of shared archive compaction -- all metaspace data are
1103 // initially allocated outside of the shared regions. ArchiveCompactor copies the
1104 // metaspace data into their final location in the shared regions.
1105 
1106 class ArchiveCompactor : AllStatic {
1107   static DumpAllocStats* _alloc_stats;
1108   static SortedSymbolClosure* _ssc;
1109 
1110   static unsigned my_hash(const address& a) {
1111     return primitive_hash<address>(a);
1112   }
1113   static bool my_equals(const address& a0, const address& a1) {
1114     return primitive_equals<address>(a0, a1);
1115   }
1116   typedef ResourceHashtable<
1117       address, address,
1118       ArchiveCompactor::my_hash,   // solaris compiler doesn't like: primitive_hash<address>
1119       ArchiveCompactor::my_equals, // solaris compiler doesn't like: primitive_equals<address>
1120       16384, ResourceObj::C_HEAP> RelocationTable;
1121   static RelocationTable* _new_loc_table;
1122 
1123 public:
1124   static void initialize() {
1125     _alloc_stats = new(ResourceObj::C_HEAP, mtInternal)DumpAllocStats;
1126     _new_loc_table = new(ResourceObj::C_HEAP, mtInternal)RelocationTable;
1127   }
1128   static DumpAllocStats* alloc_stats() {
1129     return _alloc_stats;
1130   }
1131 
1132   static void allocate(MetaspaceClosure::Ref* ref, bool read_only) {
1133     address obj = ref->obj();
1134     int bytes = ref->size() * BytesPerWord;
1135     char* p;
1136     size_t alignment = BytesPerWord;
1137     char* oldtop;
1138     char* newtop;
1139 
1140     if (read_only) {
1141       oldtop = _ro_region.top();
1142       p = _ro_region.allocate(bytes, alignment);
1143       newtop = _ro_region.top();
1144     } else {
1145       oldtop = _rw_region.top();
1146       p = _rw_region.allocate(bytes, alignment);
1147       newtop = _rw_region.top();
1148     }
1149     memcpy(p, obj, bytes);
1150     bool isnew = _new_loc_table->put(obj, (address)p);
1151     log_trace(cds)("Copy: " PTR_FORMAT " ==> " PTR_FORMAT " %d", p2i(obj), p2i(p), bytes);
1152     assert(isnew, "must be");
1153 
1154     _alloc_stats->record(ref->msotype(), int(newtop - oldtop), read_only);
1155     if (ref->msotype() == MetaspaceObj::SymbolType) {
1156       uintx delta = MetaspaceShared::object_delta(p);
1157       if (delta > MAX_SHARED_DELTA) {
1158         // This is just a sanity check and should not appear in any real world usage. This
1159         // happens only if you allocate more than 2GB of Symbols and would require
1160         // millions of shared classes.
1161         vm_exit_during_initialization("Too many Symbols in the CDS archive",
1162                                       "Please reduce the number of shared classes.");
1163       }
1164     }
1165   }
1166 
1167   static address get_new_loc(MetaspaceClosure::Ref* ref) {
1168     address* pp = _new_loc_table->get(ref->obj());
1169     assert(pp != NULL, "must be");
1170     return *pp;
1171   }
1172 
1173 private:
1174   // Makes a shallow copy of visited MetaspaceObj's
1175   class ShallowCopier: public UniqueMetaspaceClosure {
1176     bool _read_only;
1177   public:
1178     ShallowCopier(bool read_only) : _read_only(read_only) {}
1179 
1180     virtual void do_unique_ref(Ref* ref, bool read_only) {
1181       if (read_only == _read_only) {
1182         allocate(ref, read_only);
1183       }
1184     }
1185   };
1186 
1187   // Relocate embedded pointers within a MetaspaceObj's shallow copy
1188   class ShallowCopyEmbeddedRefRelocator: public UniqueMetaspaceClosure {
1189   public:
1190     virtual void do_unique_ref(Ref* ref, bool read_only) {
1191       address new_loc = get_new_loc(ref);
1192       RefRelocator refer;
1193       ref->metaspace_pointers_do_at(&refer, new_loc);
1194     }
1195   };
1196 
1197   // Relocate a reference to point to its shallow copy
1198   class RefRelocator: public MetaspaceClosure {
1199   public:
1200     virtual bool do_ref(Ref* ref, bool read_only) {
1201       if (ref->not_null()) {
1202         ref->update(get_new_loc(ref));
1203       }
1204       return false; // Do not recurse.
1205     }
1206   };
1207 
1208 #ifdef ASSERT
1209   class IsRefInArchiveChecker: public MetaspaceClosure {
1210   public:
1211     virtual bool do_ref(Ref* ref, bool read_only) {
1212       if (ref->not_null()) {
1213         char* obj = (char*)ref->obj();
1214         assert(_ro_region.contains(obj) || _rw_region.contains(obj),
1215                "must be relocated to point to CDS archive");
1216       }
1217       return false; // Do not recurse.
1218     }
1219   };
1220 #endif
1221 
1222 public:
1223   static void copy_and_compact() {
1224     // We should no longer allocate anything from the metaspace, so that
1225     // we can have a stable set of MetaspaceObjs to work with.
1226     Metaspace::freeze();
1227 
1228     ResourceMark rm;
1229     SortedSymbolClosure the_ssc; // StackObj
1230     _ssc = &the_ssc;
1231 
1232     tty->print_cr("Scanning all metaspace objects ... ");
1233     {
1234       // allocate and shallow-copy RW objects, immediately following the MC region
1235       tty->print_cr("Allocating RW objects ... ");
1236       _mc_region.pack(&_rw_region);
1237 
1238       ResourceMark rm;
1239       ShallowCopier rw_copier(false);
1240       iterate_roots(&rw_copier);
1241     }
1242     {
1243       // allocate and shallow-copy of RO object, immediately following the RW region
1244       tty->print_cr("Allocating RO objects ... ");
1245       _rw_region.pack(&_ro_region);
1246 
1247       ResourceMark rm;
1248       ShallowCopier ro_copier(true);
1249       iterate_roots(&ro_copier);
1250     }
1251     {
1252       tty->print_cr("Relocating embedded pointers ... ");
1253       ResourceMark rm;
1254       ShallowCopyEmbeddedRefRelocator emb_reloc;
1255       iterate_roots(&emb_reloc);
1256     }
1257     {
1258       tty->print_cr("Relocating external roots ... ");
1259       ResourceMark rm;
1260       RefRelocator ext_reloc;
1261       iterate_roots(&ext_reloc);
1262     }
1263 
1264 #ifdef ASSERT
1265     {
1266       tty->print_cr("Verifying external roots ... ");
1267       ResourceMark rm;
1268       IsRefInArchiveChecker checker;
1269       iterate_roots(&checker);
1270     }
1271 #endif
1272 
1273 
1274     // cleanup
1275     _ssc = NULL;
1276   }
1277 
1278   // We must relocate the System::_well_known_klasses only after we have copied the
1279   // java objects in during dump_java_heap_objects(): during the object copy, we operate on
1280   // old objects which assert that their klass is the original klass.
1281   static void relocate_well_known_klasses() {
1282     {
1283       tty->print_cr("Relocating SystemDictionary::_well_known_klasses[] ... ");
1284       ResourceMark rm;
1285       RefRelocator ext_reloc;
1286       SystemDictionary::well_known_klasses_do(&ext_reloc);
1287     }
1288     // NOTE: after this point, we shouldn't have any globals that can reach the old
1289     // objects.
1290 
1291     // We cannot use any of the objects in the heap anymore (except for the objects
1292     // in the CDS shared string regions) because their headers no longer point to
1293     // valid Klasses.
1294   }
1295 
1296   static void iterate_roots(MetaspaceClosure* it) {
1297     GrowableArray<Symbol*>* symbols = _ssc->get_sorted_symbols();
1298     for (int i=0; i<symbols->length(); i++) {
1299       it->push(symbols->adr_at(i));
1300     }
1301     if (_global_klass_objects != NULL) {
1302       // Need to fix up the pointers
1303       for (int i = 0; i < _global_klass_objects->length(); i++) {
1304         // NOTE -- this requires that the vtable is NOT yet patched, or else we are hosed.
1305         it->push(_global_klass_objects->adr_at(i));
1306       }
1307     }
1308     FileMapInfo::metaspace_pointers_do(it);
1309     SystemDictionary::classes_do(it);
1310     Universe::metaspace_pointers_do(it);
1311     SymbolTable::metaspace_pointers_do(it);
1312     vmSymbols::metaspace_pointers_do(it);
1313   }
1314 
1315   static Klass* get_relocated_klass(Klass* orig_klass) {
1316     assert(DumpSharedSpaces, "dump time only");
1317     address* pp = _new_loc_table->get((address)orig_klass);
1318     assert(pp != NULL, "must be");
1319     Klass* klass = (Klass*)(*pp);
1320     assert(klass->is_klass(), "must be");
1321     return klass;
1322   }
1323 };
1324 
1325 DumpAllocStats* ArchiveCompactor::_alloc_stats;
1326 SortedSymbolClosure* ArchiveCompactor::_ssc;
1327 ArchiveCompactor::RelocationTable* ArchiveCompactor::_new_loc_table;
1328 
1329 void VM_PopulateDumpSharedSpace::write_region(FileMapInfo* mapinfo, int region_idx,
1330                                               DumpRegion* dump_region, bool read_only,  bool allow_exec) {
1331   mapinfo->write_region(region_idx, dump_region->base(), dump_region->used(), read_only, allow_exec);
1332 }
1333 
1334 void VM_PopulateDumpSharedSpace::dump_symbols() {
1335   tty->print_cr("Dumping symbol table ...");
1336 
1337   NOT_PRODUCT(SymbolTable::verify());
1338   SymbolTable::write_to_archive();
1339 }
1340 
1341 char* VM_PopulateDumpSharedSpace::dump_read_only_tables() {
1342   char* oldtop = _ro_region.top();
1343   // Reorder the system dictionary. Moving the symbols affects
1344   // how the hash table indices are calculated.
1345   SystemDictionary::reorder_dictionary_for_sharing();
1346 
1347   tty->print("Removing java_mirror ... ");
1348   if (!MetaspaceShared::is_heap_object_archiving_allowed()) {
1349     clear_basic_type_mirrors();
1350   }
1351   remove_java_mirror_in_classes();
1352   tty->print_cr("done. ");
1353   NOT_PRODUCT(SystemDictionary::verify();)
1354 
1355   size_t buckets_bytes = SystemDictionary::count_bytes_for_buckets();
1356   char* buckets_top = _ro_region.allocate(buckets_bytes, sizeof(intptr_t));
1357   SystemDictionary::copy_buckets(buckets_top, _ro_region.top());
1358 
1359   size_t table_bytes = SystemDictionary::count_bytes_for_table();
1360   char* table_top = _ro_region.allocate(table_bytes, sizeof(intptr_t));
1361   SystemDictionary::copy_table(table_top, _ro_region.top());
1362 
1363   // Write the archived object sub-graph infos. For each klass with sub-graphs,
1364   // the info includes the static fields (sub-graph entry points) and Klasses
1365   // of objects included in the sub-graph.
1366   HeapShared::write_archived_subgraph_infos();
1367 
1368   // Write the other data to the output array.
1369   WriteClosure wc(&_ro_region);
1370   MetaspaceShared::serialize(&wc);
1371 
1372   char* newtop = _ro_region.top();
1373   ArchiveCompactor::alloc_stats()->record_other_type(int(newtop - oldtop), true);
1374   return buckets_top;
1375 }
1376 
1377 void VM_PopulateDumpSharedSpace::doit() {
1378   Thread* THREAD = VMThread::vm_thread();
1379 
1380   FileMapInfo::check_nonempty_dir_in_shared_path_table();
1381 
1382   NOT_PRODUCT(SystemDictionary::verify();)
1383   // The following guarantee is meant to ensure that no loader constraints
1384   // exist yet, since the constraints table is not shared.  This becomes
1385   // more important now that we don't re-initialize vtables/itables for
1386   // shared classes at runtime, where constraints were previously created.
1387   guarantee(SystemDictionary::constraints()->number_of_entries() == 0,
1388             "loader constraints are not saved");
1389   guarantee(SystemDictionary::placeholders()->number_of_entries() == 0,
1390           "placeholders are not saved");
1391   // Revisit and implement this if we prelink method handle call sites:
1392   guarantee(SystemDictionary::invoke_method_table() == NULL ||
1393             SystemDictionary::invoke_method_table()->number_of_entries() == 0,
1394             "invoke method table is not saved");
1395 
1396   // At this point, many classes have been loaded.
1397   // Gather systemDictionary classes in a global array and do everything to
1398   // that so we don't have to walk the SystemDictionary again.
1399   _global_klass_objects = new GrowableArray<Klass*>(1000);
1400   CollectClassesClosure collect_classes;
1401   ClassLoaderDataGraph::loaded_classes_do(&collect_classes);
1402 
1403   tty->print_cr("Number of classes %d", _global_klass_objects->length());
1404   {
1405     int num_type_array = 0, num_obj_array = 0, num_inst = 0;
1406     for (int i = 0; i < _global_klass_objects->length(); i++) {
1407       Klass* k = _global_klass_objects->at(i);
1408       if (k->is_instance_klass()) {
1409         num_inst ++;
1410       } else if (k->is_objArray_klass()) {
1411         num_obj_array ++;
1412       } else {
1413         assert(k->is_typeArray_klass(), "sanity");
1414         num_type_array ++;
1415       }
1416     }
1417     tty->print_cr("    instance classes   = %5d", num_inst);
1418     tty->print_cr("    obj array classes  = %5d", num_obj_array);
1419     tty->print_cr("    type array classes = %5d", num_type_array);
1420   }
1421 
1422   // Ensure the ConstMethods won't be modified at run-time
1423   tty->print("Updating ConstMethods ... ");
1424   rewrite_nofast_bytecodes_and_calculate_fingerprints();
1425   tty->print_cr("done. ");
1426 
1427   // Move classes from platform/system dictionaries into the boot dictionary
1428   SystemDictionary::combine_shared_dictionaries();
1429 
1430   // Make sure all classes have a correct loader type.
1431   ClassLoaderData::the_null_class_loader_data()->dictionary()->classes_do(MetaspaceShared::check_shared_class_loader_type);
1432 
1433   // Remove all references outside the metadata
1434   tty->print("Removing unshareable information ... ");
1435   remove_unshareable_in_classes();
1436   tty->print_cr("done. ");
1437 
1438   // We don't support archiving anonymous classes. Verify that they are not stored in
1439   // the any dictionaries.
1440   NOT_PRODUCT(assert_no_anonymoys_classes_in_dictionaries());
1441 
1442   SystemDictionaryShared::finalize_verification_constraints();
1443 
1444   ArchiveCompactor::initialize();
1445   ArchiveCompactor::copy_and_compact();
1446 
1447   dump_symbols();
1448 
1449   // Dump supported java heap objects
1450   _closed_archive_heap_regions = NULL;
1451   _open_archive_heap_regions = NULL;
1452   dump_java_heap_objects();
1453 
1454   ArchiveCompactor::relocate_well_known_klasses();
1455 
1456   char* read_only_tables_start = dump_read_only_tables();
1457   _ro_region.pack(&_md_region);
1458 
1459   char* vtbl_list = _md_region.top();
1460   MetaspaceShared::allocate_cpp_vtable_clones();
1461   _md_region.pack(&_od_region);
1462 
1463   // Relocate the archived class file data into the od region
1464   relocate_cached_class_file();
1465   _od_region.pack();
1466 
1467   // The 5 core spaces are allocated consecutively mc->rw->ro->md->od, so there total size
1468   // is just the spaces between the two ends.
1469   size_t core_spaces_size = _od_region.end() - _mc_region.base();
1470   assert(core_spaces_size == (size_t)align_up(core_spaces_size, Metaspace::reserve_alignment()),
1471          "should already be aligned");
1472 
1473   // During patching, some virtual methods may be called, so at this point
1474   // the vtables must contain valid methods (as filled in by CppVtableCloner::allocate).
1475   MetaspaceShared::patch_cpp_vtable_pointers();
1476 
1477   // The vtable clones contain addresses of the current process.
1478   // We don't want to write these addresses into the archive.
1479   MetaspaceShared::zero_cpp_vtable_clones_for_writing();
1480 
1481   // Create and write the archive file that maps the shared spaces.
1482 
1483   FileMapInfo* mapinfo = new FileMapInfo();
1484   mapinfo->populate_header(os::vm_allocation_granularity());
1485   mapinfo->set_read_only_tables_start(read_only_tables_start);
1486   mapinfo->set_misc_data_patching_start(vtbl_list);
1487   mapinfo->set_cds_i2i_entry_code_buffers(MetaspaceShared::cds_i2i_entry_code_buffers());
1488   mapinfo->set_cds_i2i_entry_code_buffers_size(MetaspaceShared::cds_i2i_entry_code_buffers_size());
1489   mapinfo->set_core_spaces_size(core_spaces_size);
1490 
1491   for (int pass=1; pass<=2; pass++) {
1492     if (pass == 1) {
1493       // The first pass doesn't actually write the data to disk. All it
1494       // does is to update the fields in the mapinfo->_header.
1495     } else {
1496       // After the first pass, the contents of mapinfo->_header are finalized,
1497       // so we can compute the header's CRC, and write the contents of the header
1498       // and the regions into disk.
1499       mapinfo->open_for_write();
1500       mapinfo->set_header_crc(mapinfo->compute_header_crc());
1501     }
1502     mapinfo->write_header();
1503 
1504     // NOTE: md contains the trampoline code for method entries, which are patched at run time,
1505     // so it needs to be read/write.
1506     write_region(mapinfo, MetaspaceShared::mc, &_mc_region, /*read_only=*/false,/*allow_exec=*/true);
1507     write_region(mapinfo, MetaspaceShared::rw, &_rw_region, /*read_only=*/false,/*allow_exec=*/false);
1508     write_region(mapinfo, MetaspaceShared::ro, &_ro_region, /*read_only=*/true, /*allow_exec=*/false);
1509     write_region(mapinfo, MetaspaceShared::md, &_md_region, /*read_only=*/false,/*allow_exec=*/false);
1510     write_region(mapinfo, MetaspaceShared::od, &_od_region, /*read_only=*/true, /*allow_exec=*/false);
1511 
1512     _total_string_region_size = mapinfo->write_archive_heap_regions(
1513                                         _closed_archive_heap_regions,
1514                                         MetaspaceShared::first_string,
1515                                         MetaspaceShared::max_strings);
1516     _total_open_archive_region_size = mapinfo->write_archive_heap_regions(
1517                                         _open_archive_heap_regions,
1518                                         MetaspaceShared::first_open_archive_heap_region,
1519                                         MetaspaceShared::max_open_archive_heap_region);
1520   }
1521 
1522   mapinfo->close();
1523 
1524   // Restore the vtable in case we invoke any virtual methods.
1525   MetaspaceShared::clone_cpp_vtables((intptr_t*)vtbl_list);
1526 
1527   print_region_stats();
1528 
1529   if (log_is_enabled(Info, cds)) {
1530     ArchiveCompactor::alloc_stats()->print_stats(int(_ro_region.used()), int(_rw_region.used()),
1531                                                  int(_mc_region.used()), int(_md_region.used()));
1532   }
1533 
1534   if (PrintSystemDictionaryAtExit) {
1535     SystemDictionary::print();
1536   }
1537   // There may be other pending VM operations that operate on the InstanceKlasses,
1538   // which will fail because InstanceKlasses::remove_unshareable_info()
1539   // has been called. Forget these operations and exit the VM directly.
1540   vm_direct_exit(0);
1541 }
1542 
1543 void VM_PopulateDumpSharedSpace::print_region_stats() {
1544   // Print statistics of all the regions
1545   const size_t total_reserved = _ro_region.reserved()  + _rw_region.reserved() +
1546                                 _mc_region.reserved()  + _md_region.reserved() +
1547                                 _od_region.reserved()  +
1548                                 _total_string_region_size +
1549                                 _total_open_archive_region_size;
1550   const size_t total_bytes = _ro_region.used()  + _rw_region.used() +
1551                              _mc_region.used()  + _md_region.used() +
1552                              _od_region.used()  +
1553                              _total_string_region_size +
1554                              _total_open_archive_region_size;
1555   const double total_u_perc = percent_of(total_bytes, total_reserved);
1556 
1557   _mc_region.print(total_reserved);
1558   _rw_region.print(total_reserved);
1559   _ro_region.print(total_reserved);
1560   _md_region.print(total_reserved);
1561   _od_region.print(total_reserved);
1562   print_heap_region_stats(_closed_archive_heap_regions, "st", total_reserved);
1563   print_heap_region_stats(_open_archive_heap_regions, "oa", total_reserved);
1564 
1565   tty->print_cr("total    : " SIZE_FORMAT_W(9) " [100.0%% of total] out of " SIZE_FORMAT_W(9) " bytes [%5.1f%% used]",
1566                  total_bytes, total_reserved, total_u_perc);
1567 }
1568 
1569 void VM_PopulateDumpSharedSpace::print_heap_region_stats(GrowableArray<MemRegion> *heap_mem,
1570                                                          const char *name, const size_t total_size) {
1571   int arr_len = heap_mem == NULL ? 0 : heap_mem->length();
1572   for (int i = 0; i < arr_len; i++) {
1573       char* start = (char*)heap_mem->at(i).start();
1574       size_t size = heap_mem->at(i).byte_size();
1575       char* top = start + size;
1576       tty->print_cr("%s%d space: " SIZE_FORMAT_W(9) " [ %4.1f%% of total] out of " SIZE_FORMAT_W(9) " bytes [100.0%% used] at " INTPTR_FORMAT,
1577                     name, i, size, size/double(total_size)*100.0, size, p2i(start));
1578 
1579   }
1580 }
1581 
1582 // Update a Java object to point its Klass* to the new location after
1583 // shared archive has been compacted.
1584 void MetaspaceShared::relocate_klass_ptr(oop o) {
1585   assert(DumpSharedSpaces, "sanity");
1586   Klass* k = ArchiveCompactor::get_relocated_klass(o->klass());
1587   o->set_klass(k);
1588 }
1589 
1590 Klass* MetaspaceShared::get_relocated_klass(Klass *k) {
1591   assert(DumpSharedSpaces, "sanity");
1592   return ArchiveCompactor::get_relocated_klass(k);
1593 }
1594 
1595 class LinkSharedClassesClosure : public KlassClosure {
1596   Thread* THREAD;
1597   bool    _made_progress;
1598  public:
1599   LinkSharedClassesClosure(Thread* thread) : THREAD(thread), _made_progress(false) {}
1600 
1601   void reset()               { _made_progress = false; }
1602   bool made_progress() const { return _made_progress; }
1603 
1604   void do_klass(Klass* k) {
1605     if (k->is_instance_klass()) {
1606       InstanceKlass* ik = InstanceKlass::cast(k);
1607       // Link the class to cause the bytecodes to be rewritten and the
1608       // cpcache to be created. Class verification is done according
1609       // to -Xverify setting.
1610       _made_progress |= MetaspaceShared::try_link_class(ik, THREAD);
1611       guarantee(!HAS_PENDING_EXCEPTION, "exception in link_class");
1612 
1613       ik->constants()->resolve_class_constants(THREAD);
1614     }
1615   }
1616 };
1617 
1618 class CheckSharedClassesClosure : public KlassClosure {
1619   bool    _made_progress;
1620  public:
1621   CheckSharedClassesClosure() : _made_progress(false) {}
1622 
1623   void reset()               { _made_progress = false; }
1624   bool made_progress() const { return _made_progress; }
1625   void do_klass(Klass* k) {
1626     if (k->is_instance_klass() && InstanceKlass::cast(k)->check_sharing_error_state()) {
1627       _made_progress = true;
1628     }
1629   }
1630 };
1631 
1632 void MetaspaceShared::check_shared_class_loader_type(InstanceKlass* ik) {
1633   ResourceMark rm;
1634   if (ik->shared_classpath_index() == UNREGISTERED_INDEX) {
1635     guarantee(ik->loader_type() == 0,
1636             "Class loader type must not be set for this class %s", ik->name()->as_C_string());
1637   } else {
1638     guarantee(ik->loader_type() != 0,
1639             "Class loader type must be set for this class %s", ik->name()->as_C_string());
1640   }
1641 }
1642 
1643 void MetaspaceShared::link_and_cleanup_shared_classes(TRAPS) {
1644   // We need to iterate because verification may cause additional classes
1645   // to be loaded.
1646   LinkSharedClassesClosure link_closure(THREAD);
1647   do {
1648     link_closure.reset();
1649     ClassLoaderDataGraph::loaded_classes_do(&link_closure);
1650     guarantee(!HAS_PENDING_EXCEPTION, "exception in link_class");
1651   } while (link_closure.made_progress());
1652 
1653   if (_has_error_classes) {
1654     // Mark all classes whose super class or interfaces failed verification.
1655     CheckSharedClassesClosure check_closure;
1656     do {
1657       // Not completely sure if we need to do this iteratively. Anyway,
1658       // we should come here only if there are unverifiable classes, which
1659       // shouldn't happen in normal cases. So better safe than sorry.
1660       check_closure.reset();
1661       ClassLoaderDataGraph::loaded_classes_do(&check_closure);
1662     } while (check_closure.made_progress());
1663 
1664     if (IgnoreUnverifiableClassesDuringDump) {
1665       // This is useful when running JCK or SQE tests. You should not
1666       // enable this when running real apps.
1667       SystemDictionary::remove_classes_in_error_state();
1668     } else {
1669       tty->print_cr("Please remove the unverifiable classes from your class list and try again");
1670       exit(1);
1671     }
1672   }
1673 }
1674 
1675 void MetaspaceShared::prepare_for_dumping() {
1676   Arguments::check_unsupported_dumping_properties();
1677   ClassLoader::initialize_shared_path();
1678 }
1679 
1680 // Preload classes from a list, populate the shared spaces and dump to a
1681 // file.
1682 void MetaspaceShared::preload_and_dump(TRAPS) {
1683   { TraceTime timer("Dump Shared Spaces", TRACETIME_LOG(Info, startuptime));
1684     ResourceMark rm;
1685     char class_list_path_str[JVM_MAXPATHLEN];
1686     // Preload classes to be shared.
1687     // Should use some os:: method rather than fopen() here. aB.
1688     const char* class_list_path;
1689     if (SharedClassListFile == NULL) {
1690       // Construct the path to the class list (in jre/lib)
1691       // Walk up two directories from the location of the VM and
1692       // optionally tack on "lib" (depending on platform)
1693       os::jvm_path(class_list_path_str, sizeof(class_list_path_str));
1694       for (int i = 0; i < 3; i++) {
1695         char *end = strrchr(class_list_path_str, *os::file_separator());
1696         if (end != NULL) *end = '\0';
1697       }
1698       int class_list_path_len = (int)strlen(class_list_path_str);
1699       if (class_list_path_len >= 3) {
1700         if (strcmp(class_list_path_str + class_list_path_len - 3, "lib") != 0) {
1701           if (class_list_path_len < JVM_MAXPATHLEN - 4) {
1702             jio_snprintf(class_list_path_str + class_list_path_len,
1703                          sizeof(class_list_path_str) - class_list_path_len,
1704                          "%slib", os::file_separator());
1705             class_list_path_len += 4;
1706           }
1707         }
1708       }
1709       if (class_list_path_len < JVM_MAXPATHLEN - 10) {
1710         jio_snprintf(class_list_path_str + class_list_path_len,
1711                      sizeof(class_list_path_str) - class_list_path_len,
1712                      "%sclasslist", os::file_separator());
1713       }
1714       class_list_path = class_list_path_str;
1715     } else {
1716       class_list_path = SharedClassListFile;
1717     }
1718 
1719     tty->print_cr("Loading classes to share ...");
1720     _has_error_classes = false;
1721     int class_count = preload_classes(class_list_path, THREAD);
1722     if (ExtraSharedClassListFile) {
1723       class_count += preload_classes(ExtraSharedClassListFile, THREAD);
1724     }
1725     tty->print_cr("Loading classes to share: done.");
1726 
1727     log_info(cds)("Shared spaces: preloaded %d classes", class_count);
1728 
1729     // Rewrite and link classes
1730     tty->print_cr("Rewriting and linking classes ...");
1731 
1732     // Link any classes which got missed. This would happen if we have loaded classes that
1733     // were not explicitly specified in the classlist. E.g., if an interface implemented by class K
1734     // fails verification, all other interfaces that were not specified in the classlist but
1735     // are implemented by K are not verified.
1736     link_and_cleanup_shared_classes(CATCH);
1737     tty->print_cr("Rewriting and linking classes: done");
1738 
1739     SystemDictionary::clear_invoke_method_table();
1740 
1741     VM_PopulateDumpSharedSpace op;
1742     VMThread::execute(&op);
1743   }
1744 }
1745 
1746 
1747 int MetaspaceShared::preload_classes(const char* class_list_path, TRAPS) {
1748   ClassListParser parser(class_list_path);
1749   int class_count = 0;
1750 
1751     while (parser.parse_one_line()) {
1752       Klass* klass = ClassLoaderExt::load_one_class(&parser, THREAD);
1753       if (HAS_PENDING_EXCEPTION) {
1754         if (klass == NULL &&
1755              (PENDING_EXCEPTION->klass()->name() == vmSymbols::java_lang_ClassNotFoundException())) {
1756           // print a warning only when the pending exception is class not found
1757           tty->print_cr("Preload Warning: Cannot find %s", parser.current_class_name());
1758         }
1759         CLEAR_PENDING_EXCEPTION;
1760       }
1761       if (klass != NULL) {
1762         if (log_is_enabled(Trace, cds)) {
1763           ResourceMark rm;
1764           log_trace(cds)("Shared spaces preloaded: %s", klass->external_name());
1765         }
1766 
1767         if (klass->is_instance_klass()) {
1768           InstanceKlass* ik = InstanceKlass::cast(klass);
1769 
1770           // Link the class to cause the bytecodes to be rewritten and the
1771           // cpcache to be created. The linking is done as soon as classes
1772           // are loaded in order that the related data structures (klass and
1773           // cpCache) are located together.
1774           try_link_class(ik, THREAD);
1775           guarantee(!HAS_PENDING_EXCEPTION, "exception in link_class");
1776         }
1777 
1778         class_count++;
1779       }
1780     }
1781 
1782   return class_count;
1783 }
1784 
1785 // Returns true if the class's status has changed
1786 bool MetaspaceShared::try_link_class(InstanceKlass* ik, TRAPS) {
1787   assert(DumpSharedSpaces, "should only be called during dumping");
1788   if (ik->init_state() < InstanceKlass::linked) {
1789     bool saved = BytecodeVerificationLocal;
1790     if (ik->loader_type() == 0 && ik->class_loader() == NULL) {
1791       // The verification decision is based on BytecodeVerificationRemote
1792       // for non-system classes. Since we are using the NULL classloader
1793       // to load non-system classes for customized class loaders during dumping,
1794       // we need to temporarily change BytecodeVerificationLocal to be the same as
1795       // BytecodeVerificationRemote. Note this can cause the parent system
1796       // classes also being verified. The extra overhead is acceptable during
1797       // dumping.
1798       BytecodeVerificationLocal = BytecodeVerificationRemote;
1799     }
1800     ik->link_class(THREAD);
1801     if (HAS_PENDING_EXCEPTION) {
1802       ResourceMark rm;
1803       tty->print_cr("Preload Warning: Verification failed for %s",
1804                     ik->external_name());
1805       CLEAR_PENDING_EXCEPTION;
1806       ik->set_in_error_state();
1807       _has_error_classes = true;
1808     }
1809     BytecodeVerificationLocal = saved;
1810     return true;
1811   } else {
1812     return false;
1813   }
1814 }
1815 
1816 #if INCLUDE_CDS_JAVA_HEAP
1817 void VM_PopulateDumpSharedSpace::dump_java_heap_objects() {
1818   if (!MetaspaceShared::is_heap_object_archiving_allowed()) {
1819     if (log_is_enabled(Info, cds)) {
1820       log_info(cds)(
1821         "Archived java heap is not supported as UseG1GC, "
1822         "UseCompressedOops and UseCompressedClassPointers are required."
1823         "Current settings: UseG1GC=%s, UseCompressedOops=%s, UseCompressedClassPointers=%s.",
1824         BOOL_TO_STR(UseG1GC), BOOL_TO_STR(UseCompressedOops),
1825         BOOL_TO_STR(UseCompressedClassPointers));
1826     }
1827     return;
1828   }
1829 
1830   {
1831     NoSafepointVerifier nsv;
1832 
1833     // Cache for recording where the archived objects are copied to
1834     MetaspaceShared::create_archive_object_cache();
1835 
1836     tty->print_cr("Dumping objects to closed archive heap region ...");
1837     NOT_PRODUCT(StringTable::verify());
1838     // The closed space has maximum two regions. See FileMapInfo::write_archive_heap_regions() for details.
1839     _closed_archive_heap_regions = new GrowableArray<MemRegion>(2);
1840     MetaspaceShared::dump_closed_archive_heap_objects(_closed_archive_heap_regions);
1841 
1842     tty->print_cr("Dumping objects to open archive heap region ...");
1843     _open_archive_heap_regions = new GrowableArray<MemRegion>(2);
1844     MetaspaceShared::dump_open_archive_heap_objects(_open_archive_heap_regions);
1845 
1846     MetaspaceShared::destroy_archive_object_cache();
1847   }
1848 
1849   G1HeapVerifier::verify_archive_regions();
1850 }
1851 
1852 void MetaspaceShared::dump_closed_archive_heap_objects(
1853                                     GrowableArray<MemRegion> * closed_archive) {
1854   assert(is_heap_object_archiving_allowed(), "Cannot dump java heap objects");
1855 
1856   Thread* THREAD = Thread::current();
1857   G1CollectedHeap::heap()->begin_archive_alloc_range();
1858 
1859   // Archive interned string objects
1860   StringTable::write_to_archive();
1861 
1862   G1CollectedHeap::heap()->end_archive_alloc_range(closed_archive,
1863                                                    os::vm_allocation_granularity());
1864 }
1865 
1866 void MetaspaceShared::dump_open_archive_heap_objects(
1867                                     GrowableArray<MemRegion> * open_archive) {
1868   assert(UseG1GC, "Only support G1 GC");
1869   assert(UseCompressedOops && UseCompressedClassPointers,
1870          "Only support UseCompressedOops and UseCompressedClassPointers enabled");
1871 
1872   Thread* THREAD = Thread::current();
1873   G1CollectedHeap::heap()->begin_archive_alloc_range(true /* open */);
1874 
1875   java_lang_Class::archive_basic_type_mirrors(THREAD);
1876 
1877   MetaspaceShared::archive_klass_objects(THREAD);
1878 
1879   HeapShared::archive_module_graph_objects(THREAD);
1880 
1881   G1CollectedHeap::heap()->end_archive_alloc_range(open_archive,
1882                                                    os::vm_allocation_granularity());
1883 }
1884 
1885 unsigned MetaspaceShared::obj_hash(oop const& p) {
1886   assert(!p->mark()->has_bias_pattern(),
1887          "this object should never have been locked");  // so identity_hash won't safepoin
1888   unsigned hash = (unsigned)p->identity_hash();
1889   return hash;
1890 }
1891 
1892 MetaspaceShared::ArchivedObjectCache* MetaspaceShared::_archive_object_cache = NULL;
1893 oop MetaspaceShared::find_archived_heap_object(oop obj) {
1894   assert(DumpSharedSpaces, "dump-time only");
1895   ArchivedObjectCache* cache = MetaspaceShared::archive_object_cache();
1896   oop* p = cache->get(obj);
1897   if (p != NULL) {
1898     return *p;
1899   } else {
1900     return NULL;
1901   }
1902 }
1903 
1904 oop MetaspaceShared::archive_heap_object(oop obj, Thread* THREAD) {
1905   assert(DumpSharedSpaces, "dump-time only");
1906 
1907   oop ao = find_archived_heap_object(obj);
1908   if (ao != NULL) {
1909     // already archived
1910     return ao;
1911   }
1912 
1913   int len = obj->size();
1914   if (G1CollectedHeap::heap()->is_archive_alloc_too_large(len)) {
1915     log_debug(cds, heap)("Cannot archive, object (" PTR_FORMAT ") is too large: " SIZE_FORMAT,
1916                          p2i(obj), (size_t)obj->size());
1917     return NULL;
1918   }
1919 
1920   int hash = obj->identity_hash();
1921   oop archived_oop = (oop)G1CollectedHeap::heap()->archive_mem_allocate(len);
1922   if (archived_oop != NULL) {
1923     Copy::aligned_disjoint_words((HeapWord*)obj, (HeapWord*)archived_oop, len);
1924     relocate_klass_ptr(archived_oop);
1925     ArchivedObjectCache* cache = MetaspaceShared::archive_object_cache();
1926     cache->put(obj, archived_oop);
1927     log_debug(cds, heap)("Archived heap object " PTR_FORMAT " ==> " PTR_FORMAT,
1928                          p2i(obj), p2i(archived_oop));
1929   } else {
1930     log_error(cds, heap)(
1931       "Cannot allocate space for object " PTR_FORMAT " in archived heap region",
1932       p2i(obj));
1933     vm_exit(1);
1934   }
1935   return archived_oop;
1936 }
1937 
1938 oop MetaspaceShared::materialize_archived_object(oop obj) {
1939   if (obj != NULL) {
1940     return G1CollectedHeap::heap()->materialize_archived_object(obj);
1941   }
1942   return NULL;
1943 }
1944 
1945 void MetaspaceShared::archive_klass_objects(Thread* THREAD) {
1946   int i;
1947   for (i = 0; i < _global_klass_objects->length(); i++) {
1948     Klass* k = _global_klass_objects->at(i);
1949 
1950     // archive mirror object
1951     java_lang_Class::archive_mirror(k, CHECK);
1952 
1953     // archive the resolved_referenes array
1954     if (k->is_instance_klass()) {
1955       InstanceKlass* ik = InstanceKlass::cast(k);
1956       ik->constants()->archive_resolved_references(THREAD);
1957     }
1958   }
1959 }
1960 
1961 bool MetaspaceShared::is_archive_object(oop p) {
1962   return (p == NULL) ? false : G1ArchiveAllocator::is_archive_object(p);
1963 }
1964 
1965 void MetaspaceShared::fixup_mapped_heap_regions() {
1966   FileMapInfo *mapinfo = FileMapInfo::current_info();
1967   mapinfo->fixup_mapped_heap_regions();
1968 }
1969 #endif // INCLUDE_CDS_JAVA_HEAP
1970 
1971 // Closure for serializing initialization data in from a data area
1972 // (ptr_array) read from the shared file.
1973 
1974 class ReadClosure : public SerializeClosure {
1975 private:
1976   intptr_t** _ptr_array;
1977 
1978   inline intptr_t nextPtr() {
1979     return *(*_ptr_array)++;
1980   }
1981 
1982 public:
1983   ReadClosure(intptr_t** ptr_array) { _ptr_array = ptr_array; }
1984 
1985   void do_ptr(void** p) {
1986     assert(*p == NULL, "initializing previous initialized pointer.");
1987     intptr_t obj = nextPtr();
1988     assert((intptr_t)obj >= 0 || (intptr_t)obj < -100,
1989            "hit tag while initializing ptrs.");
1990     *p = (void*)obj;
1991   }
1992 
1993   void do_u4(u4* p) {
1994     intptr_t obj = nextPtr();
1995     *p = (u4)(uintx(obj));
1996   }
1997 
1998   void do_tag(int tag) {
1999     int old_tag;
2000     old_tag = (int)(intptr_t)nextPtr();
2001     // do_int(&old_tag);
2002     assert(tag == old_tag, "old tag doesn't match");
2003     FileMapInfo::assert_mark(tag == old_tag);
2004   }
2005 
2006   void do_oop(oop *p) {
2007     narrowOop o = (narrowOop)nextPtr();
2008     if (o == 0 || !MetaspaceShared::open_archive_heap_region_mapped()) {
2009       p = NULL;
2010     } else {
2011       assert(MetaspaceShared::is_heap_object_archiving_allowed(),
2012              "Archived heap object is not allowed");
2013       assert(MetaspaceShared::open_archive_heap_region_mapped(),
2014              "Open archive heap region is not mapped");
2015       *p = CompressedOops::decode_not_null(o);
2016     }
2017   }
2018 
2019   void do_region(u_char* start, size_t size) {
2020     assert((intptr_t)start % sizeof(intptr_t) == 0, "bad alignment");
2021     assert(size % sizeof(intptr_t) == 0, "bad size");
2022     do_tag((int)size);
2023     while (size > 0) {
2024       *(intptr_t*)start = nextPtr();
2025       start += sizeof(intptr_t);
2026       size -= sizeof(intptr_t);
2027     }
2028   }
2029 
2030   bool reading() const { return true; }
2031 };
2032 
2033 // Return true if given address is in the misc data region
2034 bool MetaspaceShared::is_in_shared_region(const void* p, int idx) {
2035   return UseSharedSpaces && FileMapInfo::current_info()->is_in_shared_region(p, idx);
2036 }
2037 
2038 bool MetaspaceShared::is_in_trampoline_frame(address addr) {
2039   if (UseSharedSpaces && is_in_shared_region(addr, MetaspaceShared::mc)) {
2040     return true;
2041   }
2042   return false;
2043 }
2044 
2045 void MetaspaceShared::print_shared_spaces() {
2046   if (UseSharedSpaces) {
2047     FileMapInfo::current_info()->print_shared_spaces();
2048   }
2049 }
2050 
2051 
2052 // Map shared spaces at requested addresses and return if succeeded.
2053 bool MetaspaceShared::map_shared_spaces(FileMapInfo* mapinfo) {
2054   size_t image_alignment = mapinfo->alignment();
2055 
2056 #ifndef _WINDOWS
2057   // Map in the shared memory and then map the regions on top of it.
2058   // On Windows, don't map the memory here because it will cause the
2059   // mappings of the regions to fail.
2060   ReservedSpace shared_rs = mapinfo->reserve_shared_memory();
2061   if (!shared_rs.is_reserved()) return false;
2062 #endif
2063 
2064   assert(!DumpSharedSpaces, "Should not be called with DumpSharedSpaces");
2065 
2066   char* ro_base = NULL; char* ro_top;
2067   char* rw_base = NULL; char* rw_top;
2068   char* mc_base = NULL; char* mc_top;
2069   char* md_base = NULL; char* md_top;
2070   char* od_base = NULL; char* od_top;
2071 
2072   // Map each shared region
2073   if ((mc_base = mapinfo->map_region(mc, &mc_top)) != NULL &&
2074       (rw_base = mapinfo->map_region(rw, &rw_top)) != NULL &&
2075       (ro_base = mapinfo->map_region(ro, &ro_top)) != NULL &&
2076       (md_base = mapinfo->map_region(md, &md_top)) != NULL &&
2077       (od_base = mapinfo->map_region(od, &od_top)) != NULL &&
2078       (image_alignment == (size_t)os::vm_allocation_granularity()) &&
2079       mapinfo->validate_shared_path_table()) {
2080     // Success -- set up MetaspaceObj::_shared_metaspace_{base,top} for
2081     // fast checking in MetaspaceShared::is_in_shared_metaspace() and
2082     // MetaspaceObj::is_shared().
2083     //
2084     // We require that mc->rw->ro->md->od to be laid out consecutively, with no
2085     // gaps between them. That way, we can ensure that the OS won't be able to
2086     // allocate any new memory spaces inside _shared_metaspace_{base,top}, which
2087     // would mess up the simple comparision in MetaspaceShared::is_in_shared_metaspace().
2088     assert(mc_base < ro_base && mc_base < rw_base && mc_base < md_base && mc_base < od_base, "must be");
2089     assert(od_top  > ro_top  && od_top  > rw_top  && od_top  > md_top  && od_top  > mc_top , "must be");
2090     assert(mc_top == rw_base, "must be");
2091     assert(rw_top == ro_base, "must be");
2092     assert(ro_top == md_base, "must be");
2093     assert(md_top == od_base, "must be");
2094 
2095     MetaspaceObj::_shared_metaspace_base = (void*)mc_base;
2096     MetaspaceObj::_shared_metaspace_top  = (void*)od_top;
2097     return true;
2098   } else {
2099     // If there was a failure in mapping any of the spaces, unmap the ones
2100     // that succeeded
2101     if (ro_base != NULL) mapinfo->unmap_region(ro);
2102     if (rw_base != NULL) mapinfo->unmap_region(rw);
2103     if (mc_base != NULL) mapinfo->unmap_region(mc);
2104     if (md_base != NULL) mapinfo->unmap_region(md);
2105     if (od_base != NULL) mapinfo->unmap_region(od);
2106 #ifndef _WINDOWS
2107     // Release the entire mapped region
2108     shared_rs.release();
2109 #endif
2110     // If -Xshare:on is specified, print out the error message and exit VM,
2111     // otherwise, set UseSharedSpaces to false and continue.
2112     if (RequireSharedSpaces || PrintSharedArchiveAndExit) {
2113       vm_exit_during_initialization("Unable to use shared archive.", "Failed map_region for using -Xshare:on.");
2114     } else {
2115       FLAG_SET_DEFAULT(UseSharedSpaces, false);
2116     }
2117     return false;
2118   }
2119 }
2120 
2121 // Read the miscellaneous data from the shared file, and
2122 // serialize it out to its various destinations.
2123 
2124 void MetaspaceShared::initialize_shared_spaces() {
2125   FileMapInfo *mapinfo = FileMapInfo::current_info();
2126   _cds_i2i_entry_code_buffers = mapinfo->cds_i2i_entry_code_buffers();
2127   _cds_i2i_entry_code_buffers_size = mapinfo->cds_i2i_entry_code_buffers_size();
2128   _core_spaces_size = mapinfo->core_spaces_size();
2129   char* buffer = mapinfo->misc_data_patching_start();
2130   clone_cpp_vtables((intptr_t*)buffer);
2131 
2132   // The rest of the data is now stored in the RW region
2133   buffer = mapinfo->read_only_tables_start();
2134   int sharedDictionaryLen = *(intptr_t*)buffer;
2135   buffer += sizeof(intptr_t);
2136   int number_of_entries = *(intptr_t*)buffer;
2137   buffer += sizeof(intptr_t);
2138   SystemDictionary::set_shared_dictionary((HashtableBucket<mtClass>*)buffer,
2139                                           sharedDictionaryLen,
2140                                           number_of_entries);
2141   buffer += sharedDictionaryLen;
2142 
2143   // The following data are the linked list elements
2144   // (HashtableEntry objects) for the shared dictionary table.
2145 
2146   int len = *(intptr_t*)buffer;     // skip over shared dictionary entries
2147   buffer += sizeof(intptr_t);
2148   buffer += len;
2149 
2150   // The table of archived java heap object sub-graph infos
2151   buffer = HeapShared::read_archived_subgraph_infos(buffer);
2152 
2153   // Verify various attributes of the archive, plus initialize the
2154   // shared string/symbol tables
2155   intptr_t* array = (intptr_t*)buffer;
2156   ReadClosure rc(&array);
2157   serialize(&rc);
2158 
2159   // Initialize the run-time symbol table.
2160   SymbolTable::create_table();
2161 
2162   // Close the mapinfo file
2163   mapinfo->close();
2164 
2165   if (PrintSharedArchiveAndExit) {
2166     if (PrintSharedDictionary) {
2167       tty->print_cr("\nShared classes:\n");
2168       SystemDictionary::print_shared(tty);
2169     }
2170     if (_archive_loading_failed) {
2171       tty->print_cr("archive is invalid");
2172       vm_exit(1);
2173     } else {
2174       tty->print_cr("archive is valid");
2175       vm_exit(0);
2176     }
2177   }
2178 }
2179 
2180 // JVM/TI RedefineClasses() support:
2181 bool MetaspaceShared::remap_shared_readonly_as_readwrite() {
2182   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
2183 
2184   if (UseSharedSpaces) {
2185     // remap the shared readonly space to shared readwrite, private
2186     FileMapInfo* mapinfo = FileMapInfo::current_info();
2187     if (!mapinfo->remap_shared_readonly_as_readwrite()) {
2188       return false;
2189     }
2190     _remapped_readwrite = true;
2191   }
2192   return true;
2193 }
2194 
2195 void MetaspaceShared::report_out_of_space(const char* name, size_t needed_bytes) {
2196   // This is highly unlikely to happen on 64-bits because we have reserved a 4GB space.
2197   // On 32-bit we reserve only 256MB so you could run out of space with 100,000 classes
2198   // or so.
2199   _mc_region.print_out_of_space_msg(name, needed_bytes);
2200   _rw_region.print_out_of_space_msg(name, needed_bytes);
2201   _ro_region.print_out_of_space_msg(name, needed_bytes);
2202   _md_region.print_out_of_space_msg(name, needed_bytes);
2203   _od_region.print_out_of_space_msg(name, needed_bytes);
2204 
2205   vm_exit_during_initialization(err_msg("Unable to allocate from '%s' region", name),
2206                                 "Please reduce the number of shared classes.");
2207 }