1 /*
   2  * Copyright (c) 1997, 2023, 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 "cds/archiveHeapWriter.hpp"
  27 #include "cds/archiveHeapLoader.hpp"
  28 #include "cds/archiveBuilder.hpp"
  29 #include "cds/classPrelinker.hpp"
  30 #include "cds/heapShared.hpp"
  31 #include "classfile/classLoaderData.hpp"
  32 #include "classfile/javaClasses.inline.hpp"
  33 #include "classfile/metadataOnStackMark.hpp"
  34 #include "classfile/stringTable.hpp"
  35 #include "classfile/systemDictionary.hpp"
  36 #include "classfile/vmClasses.hpp"
  37 #include "classfile/vmSymbols.hpp"
  38 #include "code/codeCache.hpp"
  39 #include "interpreter/bootstrapInfo.hpp"
  40 #include "interpreter/linkResolver.hpp"
  41 #include "jvm.h"
  42 #include "logging/log.hpp"
  43 #include "logging/logStream.hpp"
  44 #include "memory/allocation.inline.hpp"
  45 #include "memory/metadataFactory.hpp"
  46 #include "memory/metaspaceClosure.hpp"
  47 #include "memory/oopFactory.hpp"
  48 #include "memory/resourceArea.hpp"
  49 #include "memory/universe.hpp"
  50 #include "oops/array.hpp"
  51 #include "oops/constantPool.inline.hpp"
  52 #include "oops/cpCache.inline.hpp"
  53 #include "oops/flatArrayKlass.hpp"
  54 #include "oops/instanceKlass.hpp"
  55 #include "oops/klass.inline.hpp"
  56 #include "oops/objArrayKlass.hpp"
  57 #include "oops/objArrayOop.inline.hpp"
  58 #include "oops/oop.inline.hpp"
  59 #include "oops/typeArrayOop.inline.hpp"
  60 #include "prims/jvmtiExport.hpp"
  61 #include "runtime/atomic.hpp"
  62 #include "runtime/handles.inline.hpp"
  63 #include "runtime/init.hpp"
  64 #include "runtime/javaCalls.hpp"
  65 #include "runtime/javaThread.hpp"
  66 #include "runtime/signature.hpp"
  67 #include "runtime/vframe.inline.hpp"
  68 #include "utilities/checkedCast.hpp"
  69 #include "utilities/copy.hpp"
  70 
  71 ConstantPool* ConstantPool::allocate(ClassLoaderData* loader_data, int length, TRAPS) {
  72   Array<u1>* tags = MetadataFactory::new_array<u1>(loader_data, length, 0, CHECK_NULL);
  73   int size = ConstantPool::size(length);
  74   return new (loader_data, size, MetaspaceObj::ConstantPoolType, THREAD) ConstantPool(tags);
  75 }
  76 
  77 void ConstantPool::copy_fields(const ConstantPool* orig) {
  78   // Preserve dynamic constant information from the original pool
  79   if (orig->has_dynamic_constant()) {
  80     set_has_dynamic_constant();
  81   }
  82 
  83   set_major_version(orig->major_version());
  84   set_minor_version(orig->minor_version());
  85 
  86   set_source_file_name_index(orig->source_file_name_index());
  87   set_generic_signature_index(orig->generic_signature_index());
  88 }
  89 
  90 #ifdef ASSERT
  91 
  92 // MetaspaceObj allocation invariant is calloc equivalent memory
  93 // simple verification of this here (JVM_CONSTANT_Invalid == 0 )
  94 static bool tag_array_is_zero_initialized(Array<u1>* tags) {
  95   assert(tags != nullptr, "invariant");
  96   const int length = tags->length();
  97   for (int index = 0; index < length; ++index) {
  98     if (JVM_CONSTANT_Invalid != tags->at(index)) {
  99       return false;
 100     }
 101   }
 102   return true;
 103 }
 104 
 105 #endif
 106 
 107 ConstantPool::ConstantPool(Array<u1>* tags) :
 108   _tags(tags),
 109   _length(tags->length()) {
 110 
 111     assert(_tags != nullptr, "invariant");
 112     assert(tags->length() == _length, "invariant");
 113     assert(tag_array_is_zero_initialized(tags), "invariant");
 114     assert(0 == flags(), "invariant");
 115     assert(0 == version(), "invariant");
 116     assert(nullptr == _pool_holder, "invariant");
 117 }
 118 
 119 void ConstantPool::deallocate_contents(ClassLoaderData* loader_data) {
 120   if (cache() != nullptr) {
 121     MetadataFactory::free_metadata(loader_data, cache());
 122     set_cache(nullptr);
 123   }
 124 
 125   MetadataFactory::free_array<Klass*>(loader_data, resolved_klasses());
 126   set_resolved_klasses(nullptr);
 127 
 128   MetadataFactory::free_array<jushort>(loader_data, operands());
 129   set_operands(nullptr);
 130 
 131   release_C_heap_structures();
 132 
 133   // free tag array
 134   MetadataFactory::free_array<u1>(loader_data, tags());
 135   set_tags(nullptr);
 136 }
 137 
 138 void ConstantPool::release_C_heap_structures() {
 139   // walk constant pool and decrement symbol reference counts
 140   unreference_symbols();
 141 }
 142 
 143 void ConstantPool::metaspace_pointers_do(MetaspaceClosure* it) {
 144   log_trace(cds)("Iter(ConstantPool): %p", this);
 145 
 146   it->push(&_tags, MetaspaceClosure::_writable);
 147   it->push(&_cache);
 148   it->push(&_pool_holder);
 149   it->push(&_operands);
 150   it->push(&_resolved_klasses, MetaspaceClosure::_writable);
 151 
 152   for (int i = 0; i < length(); i++) {
 153     // The only MSO's embedded in the CP entries are Symbols:
 154     //   JVM_CONSTANT_String (normal and pseudo)
 155     //   JVM_CONSTANT_Utf8
 156     constantTag ctag = tag_at(i);
 157     if (ctag.is_string() || ctag.is_utf8()) {
 158       it->push(symbol_at_addr(i));
 159     }
 160   }
 161 }
 162 
 163 objArrayOop ConstantPool::resolved_references() const {
 164   return _cache->resolved_references();
 165 }
 166 
 167 // Called from outside constant pool resolution where a resolved_reference array
 168 // may not be present.
 169 objArrayOop ConstantPool::resolved_references_or_null() const {
 170   if (_cache == nullptr) {
 171     return nullptr;
 172   } else {
 173     return _cache->resolved_references();
 174   }
 175 }
 176 
 177 oop ConstantPool::resolved_reference_at(int index) const {
 178   oop result = resolved_references()->obj_at(index);
 179   assert(oopDesc::is_oop_or_null(result), "Must be oop");
 180   return result;
 181 }
 182 
 183 // Use a CAS for multithreaded access
 184 oop ConstantPool::set_resolved_reference_at(int index, oop new_result) {
 185   assert(oopDesc::is_oop_or_null(new_result), "Must be oop");
 186   return resolved_references()->replace_if_null(index, new_result);
 187 }
 188 
 189 // Create resolved_references array and mapping array for original cp indexes
 190 // The ldc bytecode was rewritten to have the resolved reference array index so need a way
 191 // to map it back for resolving and some unlikely miscellaneous uses.
 192 // The objects created by invokedynamic are appended to this list.
 193 void ConstantPool::initialize_resolved_references(ClassLoaderData* loader_data,
 194                                                   const intStack& reference_map,
 195                                                   int constant_pool_map_length,
 196                                                   TRAPS) {
 197   // Initialized the resolved object cache.
 198   int map_length = reference_map.length();
 199   if (map_length > 0) {
 200     // Only need mapping back to constant pool entries.  The map isn't used for
 201     // invokedynamic resolved_reference entries.  For invokedynamic entries,
 202     // the constant pool cache index has the mapping back to both the constant
 203     // pool and to the resolved reference index.
 204     if (constant_pool_map_length > 0) {
 205       Array<u2>* om = MetadataFactory::new_array<u2>(loader_data, constant_pool_map_length, CHECK);
 206 
 207       for (int i = 0; i < constant_pool_map_length; i++) {
 208         int x = reference_map.at(i);
 209         assert(x == (int)(jushort) x, "klass index is too big");
 210         om->at_put(i, (jushort)x);
 211       }
 212       set_reference_map(om);
 213     }
 214 
 215     // Create Java array for holding resolved strings, methodHandles,
 216     // methodTypes, invokedynamic and invokehandle appendix objects, etc.
 217     objArrayOop stom = oopFactory::new_objArray(vmClasses::Object_klass(), map_length, CHECK);
 218     HandleMark hm(THREAD);
 219     Handle refs_handle (THREAD, stom);  // must handleize.
 220     set_resolved_references(loader_data->add_handle(refs_handle));
 221 
 222     // Create a "scratch" copy of the resolved references array to archive
 223     if (DumpSharedSpaces) {
 224       objArrayOop scratch_references = oopFactory::new_objArray(vmClasses::Object_klass(), map_length, CHECK);
 225       HeapShared::add_scratch_resolved_references(this, scratch_references);
 226     }
 227   }
 228 }
 229 
 230 void ConstantPool::allocate_resolved_klasses(ClassLoaderData* loader_data, int num_klasses, TRAPS) {
 231   // A ConstantPool can't possibly have 0xffff valid class entries,
 232   // because entry #0 must be CONSTANT_Invalid, and each class entry must refer to a UTF8
 233   // entry for the class's name. So at most we will have 0xfffe class entries.
 234   // This allows us to use 0xffff (ConstantPool::_temp_resolved_klass_index) to indicate
 235   // UnresolvedKlass entries that are temporarily created during class redefinition.
 236   assert(num_klasses < CPKlassSlot::_temp_resolved_klass_index, "sanity");
 237   assert(resolved_klasses() == nullptr, "sanity");
 238   Array<Klass*>* rk = MetadataFactory::new_array<Klass*>(loader_data, num_klasses, CHECK);
 239   set_resolved_klasses(rk);
 240 }
 241 
 242 void ConstantPool::initialize_unresolved_klasses(ClassLoaderData* loader_data, TRAPS) {
 243   int len = length();
 244   int num_klasses = 0;
 245   for (int i = 1; i <len; i++) {
 246     switch (tag_at(i).value()) {
 247     case JVM_CONSTANT_ClassIndex:
 248       {
 249         const int class_index = klass_index_at(i);
 250         unresolved_klass_at_put(i, class_index, num_klasses++);
 251       }
 252       break;
 253 #ifndef PRODUCT
 254     case JVM_CONSTANT_Class:
 255     case JVM_CONSTANT_UnresolvedClass:
 256     case JVM_CONSTANT_UnresolvedClassInError:
 257       // All of these should have been reverted back to Unresolved before calling
 258       // this function.
 259       ShouldNotReachHere();
 260 #endif
 261     }
 262   }
 263   allocate_resolved_klasses(loader_data, num_klasses, THREAD);
 264 }
 265 
 266 // Hidden class support:
 267 void ConstantPool::klass_at_put(int class_index, Klass* k) {
 268   assert(k != nullptr, "must be valid klass");
 269   CPKlassSlot kslot = klass_slot_at(class_index);
 270   int resolved_klass_index = kslot.resolved_klass_index();
 271   Klass** adr = resolved_klasses()->adr_at(resolved_klass_index);
 272   Atomic::release_store(adr, k);
 273 
 274   // The interpreter assumes when the tag is stored, the klass is resolved
 275   // and the Klass* non-null, so we need hardware store ordering here.
 276   assert(!k->name()->is_Q_signature(), "Q-type without JVM_CONSTANT_QDescBit");
 277   release_tag_at_put(class_index, JVM_CONSTANT_Class);
 278 }
 279 
 280 #if INCLUDE_CDS_JAVA_HEAP
 281 // Returns the _resolved_reference array after removing unarchivable items from it.
 282 // Returns null if this class is not supported, or _resolved_reference doesn't exist.
 283 objArrayOop ConstantPool::prepare_resolved_references_for_archiving() {
 284   if (_cache == nullptr) {
 285     return nullptr; // nothing to do
 286   }
 287 
 288   InstanceKlass *ik = pool_holder();
 289   if (!(ik->is_shared_boot_class() || ik->is_shared_platform_class() ||
 290         ik->is_shared_app_class())) {
 291     // Archiving resolved references for classes from non-builtin loaders
 292     // is not yet supported.
 293     return nullptr;
 294   }
 295 
 296   objArrayOop rr = resolved_references();
 297   if (rr != nullptr) {
 298     ConstantPool* orig_pool = ArchiveBuilder::current()->get_source_addr(this);
 299     objArrayOop scratch_rr = HeapShared::scratch_resolved_references(orig_pool);
 300     Array<u2>* ref_map = reference_map();
 301     int ref_map_len = ref_map == nullptr ? 0 : ref_map->length();
 302     int rr_len = rr->length();
 303     for (int i = 0; i < rr_len; i++) {
 304       oop obj = rr->obj_at(i);
 305       scratch_rr->obj_at_put(i, nullptr);
 306       if (obj != nullptr && i < ref_map_len) {
 307         int index = object_to_cp_index(i);
 308         if (tag_at(index).is_string()) {
 309           assert(java_lang_String::is_instance(obj), "must be");
 310           if (!ArchiveHeapWriter::is_string_too_large_to_archive(obj)) {
 311             scratch_rr->obj_at_put(i, obj);
 312           }
 313         }
 314       }
 315     }
 316     return scratch_rr;
 317   }
 318   return rr;
 319 }
 320 
 321 void ConstantPool::add_dumped_interned_strings() {
 322   objArrayOop rr = resolved_references();
 323   if (rr != nullptr) {
 324     int rr_len = rr->length();
 325     for (int i = 0; i < rr_len; i++) {
 326       oop p = rr->obj_at(i);
 327       if (java_lang_String::is_instance(p) &&
 328           !ArchiveHeapWriter::is_string_too_large_to_archive(p)) {
 329         HeapShared::add_to_dumped_interned_strings(p);
 330       }
 331     }
 332   }
 333 }
 334 #endif
 335 
 336 #if INCLUDE_CDS
 337 // CDS support. Create a new resolved_references array.
 338 void ConstantPool::restore_unshareable_info(TRAPS) {
 339   if (!_pool_holder->is_linked() && !_pool_holder->is_rewritten()) {
 340     return;
 341   }
 342   assert(is_constantPool(), "ensure C++ vtable is restored");
 343   assert(on_stack(), "should always be set for shared constant pools");
 344   assert(is_shared(), "should always be set for shared constant pools");
 345   assert(_cache != nullptr, "constant pool _cache should not be null");
 346 
 347   // Only create the new resolved references array if it hasn't been attempted before
 348   if (resolved_references() != nullptr) return;
 349 
 350   if (vmClasses::Object_klass_loaded()) {
 351     ClassLoaderData* loader_data = pool_holder()->class_loader_data();
 352 #if INCLUDE_CDS_JAVA_HEAP
 353     if (ArchiveHeapLoader::is_in_use() &&
 354         _cache->archived_references() != nullptr) {
 355       oop archived = _cache->archived_references();
 356       // Create handle for the archived resolved reference array object
 357       HandleMark hm(THREAD);
 358       Handle refs_handle(THREAD, archived);
 359       set_resolved_references(loader_data->add_handle(refs_handle));
 360       _cache->clear_archived_references();
 361     } else
 362 #endif
 363     {
 364       // No mapped archived resolved reference array
 365       // Recreate the object array and add to ClassLoaderData.
 366       int map_length = resolved_reference_length();
 367       if (map_length > 0) {
 368         objArrayOop stom = oopFactory::new_objArray(vmClasses::Object_klass(), map_length, CHECK);
 369         HandleMark hm(THREAD);
 370         Handle refs_handle(THREAD, stom);  // must handleize.
 371         set_resolved_references(loader_data->add_handle(refs_handle));
 372       }
 373     }
 374   }
 375 }
 376 
 377 void ConstantPool::remove_unshareable_info() {
 378   // Shared ConstantPools are in the RO region, so the _flags cannot be modified.
 379   // The _on_stack flag is used to prevent ConstantPools from deallocation during
 380   // class redefinition. Since shared ConstantPools cannot be deallocated anyway,
 381   // we always set _on_stack to true to avoid having to change _flags during runtime.
 382   _flags |= (_on_stack | _is_shared);
 383 
 384   if (!_pool_holder->is_linked() && !_pool_holder->verified_at_dump_time()) {
 385     return;
 386   }
 387   // Resolved references are not in the shared archive.
 388   // Save the length for restoration.  It is not necessarily the same length
 389   // as reference_map.length() if invokedynamic is saved. It is needed when
 390   // re-creating the resolved reference array if archived heap data cannot be map
 391   // at runtime.
 392   set_resolved_reference_length(
 393     resolved_references() != nullptr ? resolved_references()->length() : 0);
 394   set_resolved_references(OopHandle());
 395 
 396   bool archived = false;
 397   for (int cp_index = 1; cp_index < length(); cp_index++) { // cp_index 0 is unused
 398     switch (tag_at(cp_index).value()) {
 399     case JVM_CONSTANT_UnresolvedClassInError:
 400       {
 401         jbyte qdesc_bit = tag_at(cp_index).is_Qdescriptor_klass() ? (jbyte) JVM_CONSTANT_QDescBit : 0;
 402         tag_at_put(cp_index, JVM_CONSTANT_UnresolvedClass | qdesc_bit);
 403       }
 404       break;
 405     case JVM_CONSTANT_MethodHandleInError:
 406       tag_at_put(cp_index, JVM_CONSTANT_MethodHandle);
 407       break;
 408     case JVM_CONSTANT_MethodTypeInError:
 409       tag_at_put(cp_index, JVM_CONSTANT_MethodType);
 410       break;
 411     case JVM_CONSTANT_DynamicInError:
 412       tag_at_put(cp_index, JVM_CONSTANT_Dynamic);
 413       break;
 414     case JVM_CONSTANT_Class:
 415       archived = maybe_archive_resolved_klass_at(cp_index);
 416       ArchiveBuilder::alloc_stats()->record_klass_cp_entry(archived);
 417       break;
 418     }
 419   }
 420 
 421   if (cache() != nullptr) {
 422     // cache() is null if this class is not yet linked.
 423     cache()->remove_unshareable_info();
 424   }
 425 }
 426 
 427 bool ConstantPool::maybe_archive_resolved_klass_at(int cp_index) {
 428   assert(ArchiveBuilder::current()->is_in_buffer_space(this), "must be");
 429   assert(tag_at(cp_index).is_klass(), "must be resolved");
 430 
 431   if (pool_holder()->is_hidden() && cp_index == pool_holder()->this_class_index()) {
 432     // All references to a hidden class's own field/methods are through this
 433     // index, which was resolved in ClassFileParser::fill_instance_klass. We
 434     // must preserve it.
 435     return true;
 436   }
 437 
 438   CPKlassSlot kslot = klass_slot_at(cp_index);
 439   int resolved_klass_index = kslot.resolved_klass_index();
 440   Klass* k = resolved_klasses()->at(resolved_klass_index);
 441   // k could be null if the referenced class has been excluded via
 442   // SystemDictionaryShared::is_excluded_class().
 443 
 444   if (k != nullptr) {
 445     ConstantPool* src_cp = ArchiveBuilder::current()->get_source_addr(this);
 446     if (ClassPrelinker::can_archive_resolved_klass(src_cp, cp_index)) {
 447       if (log_is_enabled(Debug, cds, resolve)) {
 448         ResourceMark rm;
 449         log_debug(cds, resolve)("Resolved klass CP entry [%d]: %s => %s", cp_index,
 450                                 pool_holder()->external_name(), k->external_name());
 451       }
 452       return true;
 453     }
 454   }
 455 
 456   // This referenced class cannot be archived. Revert the tag to UnresolvedClass,
 457   // so that the proper class loading and initialization can happen at runtime.
 458   resolved_klasses()->at_put(resolved_klass_index, nullptr);
 459   jbyte qdesc_bit = tag_at(cp_index).is_Qdescriptor_klass() ? (jbyte) JVM_CONSTANT_QDescBit : 0;
 460   tag_at_put(cp_index, JVM_CONSTANT_UnresolvedClass | qdesc_bit);
 461   return false;
 462 }
 463 #endif // INCLUDE_CDS
 464 
 465 int ConstantPool::cp_to_object_index(int cp_index) {
 466   // this is harder don't do this so much.
 467   int i = reference_map()->find(checked_cast<u2>(cp_index));
 468   // We might not find the index for jsr292 call.
 469   return (i < 0) ? _no_index_sentinel : i;
 470 }
 471 
 472 void ConstantPool::string_at_put(int obj_index, oop str) {
 473   oop result = set_resolved_reference_at(obj_index, str);
 474   assert(result == nullptr || result == str, "Only set once or to the same string.");
 475 }
 476 
 477 void ConstantPool::trace_class_resolution(const constantPoolHandle& this_cp, Klass* k) {
 478   ResourceMark rm;
 479   int line_number = -1;
 480   const char * source_file = nullptr;
 481   if (JavaThread::current()->has_last_Java_frame()) {
 482     // try to identify the method which called this function.
 483     vframeStream vfst(JavaThread::current());
 484     if (!vfst.at_end()) {
 485       line_number = vfst.method()->line_number_from_bci(vfst.bci());
 486       Symbol* s = vfst.method()->method_holder()->source_file_name();
 487       if (s != nullptr) {
 488         source_file = s->as_C_string();
 489       }
 490     }
 491   }
 492   if (k != this_cp->pool_holder()) {
 493     // only print something if the classes are different
 494     if (source_file != nullptr) {
 495       log_debug(class, resolve)("%s %s %s:%d",
 496                  this_cp->pool_holder()->external_name(),
 497                  k->external_name(), source_file, line_number);
 498     } else {
 499       log_debug(class, resolve)("%s %s",
 500                  this_cp->pool_holder()->external_name(),
 501                  k->external_name());
 502     }
 503   }
 504 }
 505 
 506 void check_is_inline_type(Klass* k, TRAPS) {
 507   if (!k->is_inline_klass()) {
 508     THROW(vmSymbols::java_lang_IncompatibleClassChangeError());
 509   }
 510 }
 511 
 512 Klass* ConstantPool::klass_at_impl(const constantPoolHandle& this_cp, int cp_index,
 513                                    TRAPS) {
 514   JavaThread* javaThread = THREAD;
 515 
 516   // A resolved constantPool entry will contain a Klass*, otherwise a Symbol*.
 517   // It is not safe to rely on the tag bit's here, since we don't have a lock, and
 518   // the entry and tag is not updated atomically.
 519   CPKlassSlot kslot = this_cp->klass_slot_at(cp_index);
 520   int resolved_klass_index = kslot.resolved_klass_index();
 521   int name_index = kslot.name_index();
 522   assert(this_cp->tag_at(name_index).is_symbol(), "sanity");
 523 
 524   // The tag must be JVM_CONSTANT_Class in order to read the correct value from
 525   // the unresolved_klasses() array.
 526   if (this_cp->tag_at(cp_index).is_klass()) {
 527     Klass* klass = this_cp->resolved_klasses()->at(resolved_klass_index);
 528     if (klass != nullptr) {
 529       return klass;
 530     }
 531   }
 532 
 533   // This tag doesn't change back to unresolved class unless at a safepoint.
 534   if (this_cp->tag_at(cp_index).is_unresolved_klass_in_error()) {
 535     // The original attempt to resolve this constant pool entry failed so find the
 536     // class of the original error and throw another error of the same class
 537     // (JVMS 5.4.3).
 538     // If there is a detail message, pass that detail message to the error.
 539     // The JVMS does not strictly require us to duplicate the same detail message,
 540     // or any internal exception fields such as cause or stacktrace.  But since the
 541     // detail message is often a class name or other literal string, we will repeat it
 542     // if we can find it in the symbol table.
 543     throw_resolution_error(this_cp, cp_index, CHECK_NULL);
 544     ShouldNotReachHere();
 545   }
 546 
 547   HandleMark hm(THREAD);
 548   Handle mirror_handle;
 549   Symbol* name = this_cp->symbol_at(name_index);
 550   bool inline_type_signature = false;
 551   if (name->is_Q_signature()) {
 552     name = name->fundamental_name(THREAD);
 553     inline_type_signature = true;
 554   }
 555   Handle loader (THREAD, this_cp->pool_holder()->class_loader());
 556   Handle protection_domain (THREAD, this_cp->pool_holder()->protection_domain());
 557 
 558   Klass* k;
 559   {
 560     // Turn off the single stepping while doing class resolution
 561     JvmtiHideSingleStepping jhss(javaThread);
 562     k = SystemDictionary::resolve_or_fail(name, loader, protection_domain, true, THREAD);
 563   } //  JvmtiHideSingleStepping jhss(javaThread);
 564   if (inline_type_signature) {
 565     name->decrement_refcount();
 566   }
 567 
 568   if (!HAS_PENDING_EXCEPTION) {
 569     // preserve the resolved klass from unloading
 570     mirror_handle = Handle(THREAD, k->java_mirror());
 571     // Do access check for klasses
 572     verify_constant_pool_resolve(this_cp, k, THREAD);
 573   }
 574 
 575   if (!HAS_PENDING_EXCEPTION && inline_type_signature) {
 576     check_is_inline_type(k, THREAD);
 577   }
 578 
 579   if (!HAS_PENDING_EXCEPTION) {
 580     Klass* bottom_klass = nullptr;
 581     if (k->is_objArray_klass()) {
 582       bottom_klass = ObjArrayKlass::cast(k)->bottom_klass();
 583       assert(bottom_klass != nullptr, "Should be set");
 584       assert(bottom_klass->is_instance_klass() || bottom_klass->is_typeArray_klass(), "Sanity check");
 585     } else if (k->is_flatArray_klass()) {
 586       bottom_klass = FlatArrayKlass::cast(k)->element_klass();
 587       assert(bottom_klass != nullptr, "Should be set");
 588     }
 589   }
 590 
 591   // Failed to resolve class. We must record the errors so that subsequent attempts
 592   // to resolve this constant pool entry fail with the same error (JVMS 5.4.3).
 593   if (HAS_PENDING_EXCEPTION) {
 594     jbyte tag = JVM_CONSTANT_UnresolvedClass;
 595     if (this_cp->tag_at(cp_index).is_Qdescriptor_klass()) {
 596       tag |= JVM_CONSTANT_QDescBit;
 597     }
 598     save_and_throw_exception(this_cp, cp_index, constantTag(tag), CHECK_NULL);
 599     // If CHECK_NULL above doesn't return the exception, that means that
 600     // some other thread has beaten us and has resolved the class.
 601     // To preserve old behavior, we return the resolved class.
 602     Klass* klass = this_cp->resolved_klasses()->at(resolved_klass_index);
 603     assert(klass != nullptr, "must be resolved if exception was cleared");
 604     return klass;
 605   }
 606 
 607   // logging for class+resolve.
 608   if (log_is_enabled(Debug, class, resolve)){
 609     trace_class_resolution(this_cp, k);
 610   }
 611 
 612   Klass** adr = this_cp->resolved_klasses()->adr_at(resolved_klass_index);
 613   Atomic::release_store(adr, k);
 614   // The interpreter assumes when the tag is stored, the klass is resolved
 615   // and the Klass* stored in _resolved_klasses is non-null, so we need
 616   // hardware store ordering here.
 617   jbyte tag = JVM_CONSTANT_Class;
 618   if (this_cp->tag_at(cp_index).is_Qdescriptor_klass()) {
 619     tag |= JVM_CONSTANT_QDescBit;
 620   }
 621   // We also need to CAS to not overwrite an error from a racing thread.
 622 
 623   jbyte old_tag = Atomic::cmpxchg((jbyte*)this_cp->tag_addr_at(cp_index),
 624                                   (jbyte)JVM_CONSTANT_UnresolvedClass,
 625                                   tag);
 626 
 627   // We need to recheck exceptions from racing thread and return the same.
 628   if (old_tag == JVM_CONSTANT_UnresolvedClassInError) {
 629     // Remove klass.
 630     this_cp->resolved_klasses()->at_put(resolved_klass_index, nullptr);
 631     throw_resolution_error(this_cp, cp_index, CHECK_NULL);
 632   }
 633 
 634   return k;
 635 }
 636 
 637 
 638 // Does not update ConstantPool* - to avoid any exception throwing. Used
 639 // by compiler and exception handling.  Also used to avoid classloads for
 640 // instanceof operations. Returns null if the class has not been loaded or
 641 // if the verification of constant pool failed
 642 Klass* ConstantPool::klass_at_if_loaded(const constantPoolHandle& this_cp, int which) {
 643   CPKlassSlot kslot = this_cp->klass_slot_at(which);
 644   int resolved_klass_index = kslot.resolved_klass_index();
 645   int name_index = kslot.name_index();
 646   assert(this_cp->tag_at(name_index).is_symbol(), "sanity");
 647 
 648   if (this_cp->tag_at(which).is_klass()) {
 649     Klass* k = this_cp->resolved_klasses()->at(resolved_klass_index);
 650     assert(k != nullptr, "should be resolved");
 651     return k;
 652   } else if (this_cp->tag_at(which).is_unresolved_klass_in_error()) {
 653     return nullptr;
 654   } else {
 655     Thread* current = Thread::current();
 656     HandleMark hm(current);
 657     Symbol* name = this_cp->symbol_at(name_index);
 658     oop loader = this_cp->pool_holder()->class_loader();
 659     oop protection_domain = this_cp->pool_holder()->protection_domain();
 660     Handle h_prot (current, protection_domain);
 661     Handle h_loader (current, loader);
 662     Klass* k = SystemDictionary::find_instance_klass(current, name, h_loader, h_prot);
 663 
 664     // Avoid constant pool verification at a safepoint, as it takes the Module_lock.
 665     if (k != nullptr && current->is_Java_thread()) {
 666       // Make sure that resolving is legal
 667       JavaThread* THREAD = JavaThread::cast(current); // For exception macros.
 668       ExceptionMark em(THREAD);
 669       // return null if verification fails
 670       verify_constant_pool_resolve(this_cp, k, THREAD);
 671       if (HAS_PENDING_EXCEPTION) {
 672         CLEAR_PENDING_EXCEPTION;
 673         return nullptr;
 674       }
 675       return k;
 676     } else {
 677       return k;
 678     }
 679   }
 680 }
 681 
 682 Method* ConstantPool::method_at_if_loaded(const constantPoolHandle& cpool,
 683                                                    int which) {
 684   if (cpool->cache() == nullptr)  return nullptr;  // nothing to load yet
 685   int cache_index = decode_cpcache_index(which, true);
 686   if (!(cache_index >= 0 && cache_index < cpool->cache()->length())) {
 687     // FIXME: should be an assert
 688     log_debug(class, resolve)("bad operand %d in:", which); cpool->print();
 689     return nullptr;
 690   }
 691   ConstantPoolCacheEntry* e = cpool->cache()->entry_at(cache_index);
 692   return e->method_if_resolved(cpool);
 693 }
 694 
 695 
 696 bool ConstantPool::has_appendix_at_if_loaded(const constantPoolHandle& cpool, int which) {
 697   if (cpool->cache() == nullptr)  return false;  // nothing to load yet
 698   if (is_invokedynamic_index(which)) {
 699     int indy_index = decode_invokedynamic_index(which);
 700     return cpool->resolved_indy_entry_at(indy_index)->has_appendix();
 701   } else {
 702     int cache_index = decode_cpcache_index(which, true);
 703     ConstantPoolCacheEntry* e = cpool->cache()->entry_at(cache_index);
 704     return e->has_appendix();
 705   }
 706 }
 707 
 708 oop ConstantPool::appendix_at_if_loaded(const constantPoolHandle& cpool, int which) {
 709   if (cpool->cache() == nullptr)  return nullptr;  // nothing to load yet
 710   if (is_invokedynamic_index(which)) {
 711     int indy_index = decode_invokedynamic_index(which);
 712     return cpool->resolved_reference_from_indy(indy_index);
 713   } else {
 714     int cache_index = decode_cpcache_index(which, true);
 715     ConstantPoolCacheEntry* e = cpool->cache()->entry_at(cache_index);
 716     return e->appendix_if_resolved(cpool);
 717   }
 718 }
 719 
 720 
 721 bool ConstantPool::has_local_signature_at_if_loaded(const constantPoolHandle& cpool, int which) {
 722   if (cpool->cache() == nullptr)  return false;  // nothing to load yet
 723   int cache_index = decode_cpcache_index(which, true);
 724   if (is_invokedynamic_index(which)) {
 725     return cpool->resolved_indy_entry_at(cache_index)->has_local_signature();
 726   } else {
 727     ConstantPoolCacheEntry* e = cpool->cache()->entry_at(cache_index);
 728     return e->has_local_signature();
 729   }
 730 }
 731 
 732 // Translate index, which could be CPCache index or Indy index, to a constant pool index
 733 int ConstantPool::to_cp_index(int index, Bytecodes::Code code) {
 734   assert(cache() != nullptr, "'index' is a rewritten index so this class must have been rewritten");
 735   switch(code) {
 736     case Bytecodes::_invokedynamic:
 737       return invokedynamic_bootstrap_ref_index_at(index);
 738     case Bytecodes::_getfield:
 739     case Bytecodes::_getstatic:
 740     case Bytecodes::_putfield:
 741     case Bytecodes::_putstatic:
 742     case Bytecodes::_withfield:
 743       return resolved_field_entry_at(index)->constant_pool_index();
 744     case Bytecodes::_invokeinterface:
 745     case Bytecodes::_invokehandle:
 746     case Bytecodes::_invokespecial:
 747     case Bytecodes::_invokestatic:
 748     case Bytecodes::_invokevirtual:
 749       // TODO: handle resolved method entries with new structure
 750     default:
 751       // change byte-ordering and go via cache
 752       return remap_instruction_operand_from_cache(index);
 753   }
 754 }
 755 
 756 u2 ConstantPool::uncached_name_and_type_ref_index_at(int cp_index)  {
 757   if (tag_at(cp_index).has_bootstrap()) {
 758     u2 pool_index = bootstrap_name_and_type_ref_index_at(cp_index);
 759     assert(tag_at(pool_index).is_name_and_type(), "");
 760     return pool_index;
 761   }
 762   assert(tag_at(cp_index).is_field_or_method(), "Corrupted constant pool");
 763   assert(!tag_at(cp_index).has_bootstrap(), "Must be handled above");
 764   jint ref_index = *int_at_addr(cp_index);
 765   return extract_high_short_from_int(ref_index);
 766 }
 767 
 768 u2 ConstantPool::name_and_type_ref_index_at(int index, Bytecodes::Code code) {
 769   return uncached_name_and_type_ref_index_at(to_cp_index(index, code));
 770 }
 771 
 772 constantTag ConstantPool::tag_ref_at(int which, Bytecodes::Code code) {
 773   // which may be either a Constant Pool index or a rewritten index
 774   int pool_index = which;
 775   assert(cache() != nullptr, "'index' is a rewritten index so this class must have been rewritten");
 776   pool_index = to_cp_index(which, code);
 777   return tag_at(pool_index);
 778 }
 779 
 780 u2 ConstantPool::uncached_klass_ref_index_at(int cp_index) {
 781   assert(tag_at(cp_index).is_field_or_method(), "Corrupted constant pool");
 782   jint ref_index = *int_at_addr(cp_index);
 783   return extract_low_short_from_int(ref_index);
 784 }
 785 
 786 u2 ConstantPool::klass_ref_index_at(int index, Bytecodes::Code code) {
 787   guarantee(!ConstantPool::is_invokedynamic_index(index),
 788             "an invokedynamic instruction does not have a klass");
 789   assert(code != Bytecodes::_invokedynamic,
 790             "an invokedynamic instruction does not have a klass");
 791   return uncached_klass_ref_index_at(to_cp_index(index, code));
 792 }
 793 
 794 int ConstantPool::remap_instruction_operand_from_cache(int operand) {
 795   int cpc_index = operand;
 796   DEBUG_ONLY(cpc_index -= CPCACHE_INDEX_TAG);
 797   assert((int)(u2)cpc_index == cpc_index, "clean u2");
 798   int member_index = cache()->entry_at(cpc_index)->constant_pool_index();
 799   return member_index;
 800 }
 801 
 802 
 803 void ConstantPool::verify_constant_pool_resolve(const constantPoolHandle& this_cp, Klass* k, TRAPS) {
 804   if (!(k->is_instance_klass() || k->is_objArray_klass())) {
 805     return;  // short cut, typeArray klass is always accessible
 806   }
 807   Klass* holder = this_cp->pool_holder();
 808   LinkResolver::check_klass_accessibility(holder, k, CHECK);
 809 }
 810 
 811 
 812 u2 ConstantPool::name_ref_index_at(int cp_index) {
 813   jint ref_index = name_and_type_at(cp_index);
 814   return extract_low_short_from_int(ref_index);
 815 }
 816 
 817 
 818 u2 ConstantPool::signature_ref_index_at(int cp_index) {
 819   jint ref_index = name_and_type_at(cp_index);
 820   return extract_high_short_from_int(ref_index);
 821 }
 822 
 823 
 824 Klass* ConstantPool::klass_ref_at(int which, Bytecodes::Code code, TRAPS) {
 825   return klass_at(klass_ref_index_at(which, code), THREAD);
 826 }
 827 
 828 Symbol* ConstantPool::klass_name_at(int cp_index) const {
 829   return symbol_at(klass_slot_at(cp_index).name_index());
 830 }
 831 
 832 Symbol* ConstantPool::klass_ref_at_noresolve(int which, Bytecodes::Code code) {
 833   jint ref_index = klass_ref_index_at(which, code);
 834   return klass_at_noresolve(ref_index);
 835 }
 836 
 837 Symbol* ConstantPool::uncached_klass_ref_at_noresolve(int cp_index) {
 838   jint ref_index = uncached_klass_ref_index_at(cp_index);
 839   return klass_at_noresolve(ref_index);
 840 }
 841 
 842 char* ConstantPool::string_at_noresolve(int cp_index) {
 843   return unresolved_string_at(cp_index)->as_C_string();
 844 }
 845 
 846 BasicType ConstantPool::basic_type_for_signature_at(int cp_index) const {
 847   return Signature::basic_type(symbol_at(cp_index));
 848 }
 849 
 850 
 851 void ConstantPool::resolve_string_constants_impl(const constantPoolHandle& this_cp, TRAPS) {
 852   for (int index = 1; index < this_cp->length(); index++) { // Index 0 is unused
 853     if (this_cp->tag_at(index).is_string()) {
 854       this_cp->string_at(index, CHECK);
 855     }
 856   }
 857 }
 858 
 859 static Symbol* exception_message(const constantPoolHandle& this_cp, int which, constantTag tag, oop pending_exception) {
 860   // Dig out the detailed message to reuse if possible
 861   Symbol* message = java_lang_Throwable::detail_message(pending_exception);
 862   if (message != nullptr) {
 863     return message;
 864   }
 865 
 866   // Return specific message for the tag
 867   switch (tag.value()) {
 868   case JVM_CONSTANT_UnresolvedClass:
 869     // return the class name in the error message
 870     message = this_cp->klass_name_at(which);
 871     break;
 872   case JVM_CONSTANT_MethodHandle:
 873     // return the method handle name in the error message
 874     message = this_cp->method_handle_name_ref_at(which);
 875     break;
 876   case JVM_CONSTANT_MethodType:
 877     // return the method type signature in the error message
 878     message = this_cp->method_type_signature_at(which);
 879     break;
 880   case JVM_CONSTANT_Dynamic:
 881     // return the name of the condy in the error message
 882     message = this_cp->uncached_name_ref_at(which);
 883     break;
 884   default:
 885     ShouldNotReachHere();
 886   }
 887 
 888   return message;
 889 }
 890 
 891 static void add_resolution_error(const constantPoolHandle& this_cp, int which,
 892                                  constantTag tag, oop pending_exception) {
 893 
 894   Symbol* error = pending_exception->klass()->name();
 895   oop cause = java_lang_Throwable::cause(pending_exception);
 896 
 897   // Also dig out the exception cause, if present.
 898   Symbol* cause_sym = nullptr;
 899   Symbol* cause_msg = nullptr;
 900   if (cause != nullptr && cause != pending_exception) {
 901     cause_sym = cause->klass()->name();
 902     cause_msg = java_lang_Throwable::detail_message(cause);
 903   }
 904 
 905   Symbol* message = exception_message(this_cp, which, tag, pending_exception);
 906   SystemDictionary::add_resolution_error(this_cp, which, error, message, cause_sym, cause_msg);
 907 }
 908 
 909 
 910 void ConstantPool::throw_resolution_error(const constantPoolHandle& this_cp, int which, TRAPS) {
 911   ResourceMark rm(THREAD);
 912   Symbol* message = nullptr;
 913   Symbol* cause = nullptr;
 914   Symbol* cause_msg = nullptr;
 915   Symbol* error = SystemDictionary::find_resolution_error(this_cp, which, &message, &cause, &cause_msg);
 916   assert(error != nullptr, "checking");
 917   const char* cause_str = cause_msg != nullptr ? cause_msg->as_C_string() : nullptr;
 918 
 919   CLEAR_PENDING_EXCEPTION;
 920   if (message != nullptr) {
 921     char* msg = message->as_C_string();
 922     if (cause != nullptr) {
 923       Handle h_cause = Exceptions::new_exception(THREAD, cause, cause_str);
 924       THROW_MSG_CAUSE(error, msg, h_cause);
 925     } else {
 926       THROW_MSG(error, msg);
 927     }
 928   } else {
 929     if (cause != nullptr) {
 930       Handle h_cause = Exceptions::new_exception(THREAD, cause, cause_str);
 931       THROW_CAUSE(error, h_cause);
 932     } else {
 933       THROW(error);
 934     }
 935   }
 936 }
 937 
 938 // If resolution for Class, Dynamic constant, MethodHandle or MethodType fails, save the
 939 // exception in the resolution error table, so that the same exception is thrown again.
 940 void ConstantPool::save_and_throw_exception(const constantPoolHandle& this_cp, int cp_index,
 941                                             constantTag tag, TRAPS) {
 942 
 943   int error_tag = tag.error_value();
 944 
 945   if (!PENDING_EXCEPTION->
 946     is_a(vmClasses::LinkageError_klass())) {
 947     // Just throw the exception and don't prevent these classes from
 948     // being loaded due to virtual machine errors like StackOverflow
 949     // and OutOfMemoryError, etc, or if the thread was hit by stop()
 950     // Needs clarification to section 5.4.3 of the VM spec (see 6308271)
 951   } else if (this_cp->tag_at(cp_index).value() != error_tag) {
 952     add_resolution_error(this_cp, cp_index, tag, PENDING_EXCEPTION);
 953     // CAS in the tag.  If a thread beat us to registering this error that's fine.
 954     // If another thread resolved the reference, this is a race condition. This
 955     // thread may have had a security manager or something temporary.
 956     // This doesn't deterministically get an error.   So why do we save this?
 957     // We save this because jvmti can add classes to the bootclass path after
 958     // this error, so it needs to get the same error if the error is first.
 959     jbyte old_tag = Atomic::cmpxchg((jbyte*)this_cp->tag_addr_at(cp_index),
 960                                     (jbyte)tag.value(),
 961                                     (jbyte)error_tag);
 962     if (old_tag != error_tag && old_tag != tag.value()) {
 963       // MethodHandles and MethodType doesn't change to resolved version.
 964       assert(this_cp->tag_at(cp_index).is_klass(), "Wrong tag value");
 965       // Forget the exception and use the resolved class.
 966       CLEAR_PENDING_EXCEPTION;
 967     }
 968   } else {
 969     // some other thread put this in error state
 970     throw_resolution_error(this_cp, cp_index, CHECK);
 971   }
 972 }
 973 
 974 constantTag ConstantPool::constant_tag_at(int cp_index) {
 975   constantTag tag = tag_at(cp_index);
 976   if (tag.is_dynamic_constant()) {
 977     BasicType bt = basic_type_for_constant_at(cp_index);
 978     return constantTag(constantTag::type2tag(bt));
 979   }
 980   return tag;
 981 }
 982 
 983 BasicType ConstantPool::basic_type_for_constant_at(int cp_index) {
 984   constantTag tag = tag_at(cp_index);
 985   if (tag.is_dynamic_constant() ||
 986       tag.is_dynamic_constant_in_error()) {
 987     // have to look at the signature for this one
 988     Symbol* constant_type = uncached_signature_ref_at(cp_index);
 989     return Signature::basic_type(constant_type);
 990   }
 991   return tag.basic_type();
 992 }
 993 
 994 // Called to resolve constants in the constant pool and return an oop.
 995 // Some constant pool entries cache their resolved oop. This is also
 996 // called to create oops from constants to use in arguments for invokedynamic
 997 oop ConstantPool::resolve_constant_at_impl(const constantPoolHandle& this_cp,
 998                                            int cp_index, int cache_index,
 999                                            bool* status_return, TRAPS) {
1000   oop result_oop = nullptr;
1001 
1002   if (cache_index == _possible_index_sentinel) {
1003     // It is possible that this constant is one which is cached in the objects.
1004     // We'll do a linear search.  This should be OK because this usage is rare.
1005     // FIXME: If bootstrap specifiers stress this code, consider putting in
1006     // a reverse index.  Binary search over a short array should do it.
1007     assert(cp_index > 0, "valid constant pool index");
1008     cache_index = this_cp->cp_to_object_index(cp_index);
1009   }
1010   assert(cache_index == _no_index_sentinel || cache_index >= 0, "");
1011   assert(cp_index == _no_index_sentinel || cp_index >= 0, "");
1012 
1013   if (cache_index >= 0) {
1014     result_oop = this_cp->resolved_reference_at(cache_index);
1015     if (result_oop != nullptr) {
1016       if (result_oop == Universe::the_null_sentinel()) {
1017         DEBUG_ONLY(int temp_index = (cp_index >= 0 ? cp_index : this_cp->object_to_cp_index(cache_index)));
1018         assert(this_cp->tag_at(temp_index).is_dynamic_constant(), "only condy uses the null sentinel");
1019         result_oop = nullptr;
1020       }
1021       if (status_return != nullptr)  (*status_return) = true;
1022       return result_oop;
1023       // That was easy...
1024     }
1025     cp_index = this_cp->object_to_cp_index(cache_index);
1026   }
1027 
1028   jvalue prim_value;  // temp used only in a few cases below
1029 
1030   constantTag tag = this_cp->tag_at(cp_index);
1031 
1032   if (status_return != nullptr) {
1033     // don't trigger resolution if the constant might need it
1034     switch (tag.value()) {
1035     case JVM_CONSTANT_Class:
1036     {
1037       CPKlassSlot kslot = this_cp->klass_slot_at(cp_index);
1038       int resolved_klass_index = kslot.resolved_klass_index();
1039       if (this_cp->resolved_klasses()->at(resolved_klass_index) == nullptr) {
1040         (*status_return) = false;
1041         return nullptr;
1042       }
1043       // the klass is waiting in the CP; go get it
1044       break;
1045     }
1046     case JVM_CONSTANT_String:
1047     case JVM_CONSTANT_Integer:
1048     case JVM_CONSTANT_Float:
1049     case JVM_CONSTANT_Long:
1050     case JVM_CONSTANT_Double:
1051       // these guys trigger OOM at worst
1052       break;
1053     default:
1054       (*status_return) = false;
1055       return nullptr;
1056     }
1057     // from now on there is either success or an OOME
1058     (*status_return) = true;
1059   }
1060 
1061   switch (tag.value()) {
1062 
1063   case JVM_CONSTANT_UnresolvedClass:
1064   case JVM_CONSTANT_Class:
1065     {
1066       assert(cache_index == _no_index_sentinel, "should not have been set");
1067       Klass* resolved = klass_at_impl(this_cp, cp_index, CHECK_NULL);
1068       // ldc wants the java mirror.
1069       result_oop = tag.is_Qdescriptor_klass()
1070                       ? InlineKlass::cast(resolved)->val_mirror()
1071                       : resolved->java_mirror();
1072       break;
1073     }
1074 
1075   case JVM_CONSTANT_Dynamic:
1076     {
1077       // Resolve the Dynamically-Computed constant to invoke the BSM in order to obtain the resulting oop.
1078       BootstrapInfo bootstrap_specifier(this_cp, cp_index);
1079 
1080       // The initial step in resolving an unresolved symbolic reference to a
1081       // dynamically-computed constant is to resolve the symbolic reference to a
1082       // method handle which will be the bootstrap method for the dynamically-computed
1083       // constant. If resolution of the java.lang.invoke.MethodHandle for the bootstrap
1084       // method fails, then a MethodHandleInError is stored at the corresponding
1085       // bootstrap method's CP index for the CONSTANT_MethodHandle_info. No need to
1086       // set a DynamicConstantInError here since any subsequent use of this
1087       // bootstrap method will encounter the resolution of MethodHandleInError.
1088       // Both the first, (resolution of the BSM and its static arguments), and the second tasks,
1089       // (invocation of the BSM), of JVMS Section 5.4.3.6 occur within invoke_bootstrap_method()
1090       // for the bootstrap_specifier created above.
1091       SystemDictionary::invoke_bootstrap_method(bootstrap_specifier, THREAD);
1092       Exceptions::wrap_dynamic_exception(/* is_indy */ false, THREAD);
1093       if (HAS_PENDING_EXCEPTION) {
1094         // Resolution failure of the dynamically-computed constant, save_and_throw_exception
1095         // will check for a LinkageError and store a DynamicConstantInError.
1096         save_and_throw_exception(this_cp, cp_index, tag, CHECK_NULL);
1097       }
1098       result_oop = bootstrap_specifier.resolved_value()();
1099       BasicType type = Signature::basic_type(bootstrap_specifier.signature());
1100       if (!is_reference_type(type)) {
1101         // Make sure the primitive value is properly boxed.
1102         // This is a JDK responsibility.
1103         const char* fail = nullptr;
1104         if (result_oop == nullptr) {
1105           fail = "null result instead of box";
1106         } else if (!is_java_primitive(type)) {
1107           // FIXME: support value types via unboxing
1108           fail = "can only handle references and primitives";
1109         } else if (!java_lang_boxing_object::is_instance(result_oop, type)) {
1110           fail = "primitive is not properly boxed";
1111         }
1112         if (fail != nullptr) {
1113           // Since this exception is not a LinkageError, throw exception
1114           // but do not save a DynamicInError resolution result.
1115           // See section 5.4.3 of the VM spec.
1116           THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), fail);
1117         }
1118       }
1119 
1120       LogTarget(Debug, methodhandles, condy) lt_condy;
1121       if (lt_condy.is_enabled()) {
1122         LogStream ls(lt_condy);
1123         bootstrap_specifier.print_msg_on(&ls, "resolve_constant_at_impl");
1124       }
1125       break;
1126     }
1127 
1128   case JVM_CONSTANT_String:
1129     assert(cache_index != _no_index_sentinel, "should have been set");
1130     result_oop = string_at_impl(this_cp, cp_index, cache_index, CHECK_NULL);
1131     break;
1132 
1133   case JVM_CONSTANT_MethodHandle:
1134     {
1135       int ref_kind                 = this_cp->method_handle_ref_kind_at(cp_index);
1136       int callee_index             = this_cp->method_handle_klass_index_at(cp_index);
1137       Symbol*  name =      this_cp->method_handle_name_ref_at(cp_index);
1138       Symbol*  signature = this_cp->method_handle_signature_ref_at(cp_index);
1139       constantTag m_tag  = this_cp->tag_at(this_cp->method_handle_index_at(cp_index));
1140       { ResourceMark rm(THREAD);
1141         log_debug(class, resolve)("resolve JVM_CONSTANT_MethodHandle:%d [%d/%d/%d] %s.%s",
1142                               ref_kind, cp_index, this_cp->method_handle_index_at(cp_index),
1143                               callee_index, name->as_C_string(), signature->as_C_string());
1144       }
1145 
1146       Klass* callee = klass_at_impl(this_cp, callee_index, THREAD);
1147       if (HAS_PENDING_EXCEPTION) {
1148         save_and_throw_exception(this_cp, cp_index, tag, CHECK_NULL);
1149       }
1150 
1151       // Check constant pool method consistency
1152       if ((callee->is_interface() && m_tag.is_method()) ||
1153           (!callee->is_interface() && m_tag.is_interface_method())) {
1154         ResourceMark rm(THREAD);
1155         stringStream ss;
1156         ss.print("Inconsistent constant pool data in classfile for class %s. "
1157                  "Method '", callee->name()->as_C_string());
1158         signature->print_as_signature_external_return_type(&ss);
1159         ss.print(" %s(", name->as_C_string());
1160         signature->print_as_signature_external_parameters(&ss);
1161         ss.print(")' at index %d is %s and should be %s",
1162                  cp_index,
1163                  callee->is_interface() ? "CONSTANT_MethodRef" : "CONSTANT_InterfaceMethodRef",
1164                  callee->is_interface() ? "CONSTANT_InterfaceMethodRef" : "CONSTANT_MethodRef");
1165         Exceptions::fthrow(THREAD_AND_LOCATION, vmSymbols::java_lang_IncompatibleClassChangeError(), "%s", ss.as_string());
1166         save_and_throw_exception(this_cp, cp_index, tag, CHECK_NULL);
1167       }
1168 
1169       Klass* klass = this_cp->pool_holder();
1170       HandleMark hm(THREAD);
1171       Handle value = SystemDictionary::link_method_handle_constant(klass, ref_kind,
1172                                                                    callee, name, signature,
1173                                                                    THREAD);
1174       if (HAS_PENDING_EXCEPTION) {
1175         save_and_throw_exception(this_cp, cp_index, tag, CHECK_NULL);
1176       }
1177       result_oop = value();
1178       break;
1179     }
1180 
1181   case JVM_CONSTANT_MethodType:
1182     {
1183       Symbol*  signature = this_cp->method_type_signature_at(cp_index);
1184       { ResourceMark rm(THREAD);
1185         log_debug(class, resolve)("resolve JVM_CONSTANT_MethodType [%d/%d] %s",
1186                               cp_index, this_cp->method_type_index_at(cp_index),
1187                               signature->as_C_string());
1188       }
1189       Klass* klass = this_cp->pool_holder();
1190       HandleMark hm(THREAD);
1191       Handle value = SystemDictionary::find_method_handle_type(signature, klass, THREAD);
1192       result_oop = value();
1193       if (HAS_PENDING_EXCEPTION) {
1194         save_and_throw_exception(this_cp, cp_index, tag, CHECK_NULL);
1195       }
1196       break;
1197     }
1198 
1199   case JVM_CONSTANT_Integer:
1200     assert(cache_index == _no_index_sentinel, "should not have been set");
1201     prim_value.i = this_cp->int_at(cp_index);
1202     result_oop = java_lang_boxing_object::create(T_INT, &prim_value, CHECK_NULL);
1203     break;
1204 
1205   case JVM_CONSTANT_Float:
1206     assert(cache_index == _no_index_sentinel, "should not have been set");
1207     prim_value.f = this_cp->float_at(cp_index);
1208     result_oop = java_lang_boxing_object::create(T_FLOAT, &prim_value, CHECK_NULL);
1209     break;
1210 
1211   case JVM_CONSTANT_Long:
1212     assert(cache_index == _no_index_sentinel, "should not have been set");
1213     prim_value.j = this_cp->long_at(cp_index);
1214     result_oop = java_lang_boxing_object::create(T_LONG, &prim_value, CHECK_NULL);
1215     break;
1216 
1217   case JVM_CONSTANT_Double:
1218     assert(cache_index == _no_index_sentinel, "should not have been set");
1219     prim_value.d = this_cp->double_at(cp_index);
1220     result_oop = java_lang_boxing_object::create(T_DOUBLE, &prim_value, CHECK_NULL);
1221     break;
1222 
1223   case JVM_CONSTANT_UnresolvedClassInError:
1224   case JVM_CONSTANT_DynamicInError:
1225   case JVM_CONSTANT_MethodHandleInError:
1226   case JVM_CONSTANT_MethodTypeInError:
1227     throw_resolution_error(this_cp, cp_index, CHECK_NULL);
1228     break;
1229 
1230   default:
1231     fatal("unexpected constant tag at CP %p[%d/%d] = %d", this_cp(), cp_index, cache_index, tag.value());
1232     break;
1233   }
1234 
1235   if (cache_index >= 0) {
1236     // Benign race condition:  resolved_references may already be filled in.
1237     // The important thing here is that all threads pick up the same result.
1238     // It doesn't matter which racing thread wins, as long as only one
1239     // result is used by all threads, and all future queries.
1240     oop new_result = (result_oop == nullptr ? Universe::the_null_sentinel() : result_oop);
1241     oop old_result = this_cp->set_resolved_reference_at(cache_index, new_result);
1242     if (old_result == nullptr) {
1243       return result_oop;  // was installed
1244     } else {
1245       // Return the winning thread's result.  This can be different than
1246       // the result here for MethodHandles.
1247       if (old_result == Universe::the_null_sentinel())
1248         old_result = nullptr;
1249       return old_result;
1250     }
1251   } else {
1252     assert(result_oop != Universe::the_null_sentinel(), "");
1253     return result_oop;
1254   }
1255 }
1256 
1257 oop ConstantPool::uncached_string_at(int cp_index, TRAPS) {
1258   Symbol* sym = unresolved_string_at(cp_index);
1259   oop str = StringTable::intern(sym, CHECK_(nullptr));
1260   assert(java_lang_String::is_instance(str), "must be string");
1261   return str;
1262 }
1263 
1264 void ConstantPool::copy_bootstrap_arguments_at_impl(const constantPoolHandle& this_cp, int cp_index,
1265                                                     int start_arg, int end_arg,
1266                                                     objArrayHandle info, int pos,
1267                                                     bool must_resolve, Handle if_not_available,
1268                                                     TRAPS) {
1269   int limit = pos + end_arg - start_arg;
1270   // checks: cp_index in range [0..this_cp->length),
1271   // tag at cp_index, start..end in range [0..this_cp->bootstrap_argument_count],
1272   // info array non-null, pos..limit in [0..info.length]
1273   if ((0 >= cp_index    || cp_index >= this_cp->length())  ||
1274       !(this_cp->tag_at(cp_index).is_invoke_dynamic()    ||
1275         this_cp->tag_at(cp_index).is_dynamic_constant()) ||
1276       (0 > start_arg || start_arg > end_arg) ||
1277       (end_arg > this_cp->bootstrap_argument_count_at(cp_index)) ||
1278       (0 > pos       || pos > limit)         ||
1279       (info.is_null() || limit > info->length())) {
1280     // An index or something else went wrong; throw an error.
1281     // Since this is an internal API, we don't expect this,
1282     // so we don't bother to craft a nice message.
1283     THROW_MSG(vmSymbols::java_lang_LinkageError(), "bad BSM argument access");
1284   }
1285   // now we can loop safely
1286   int info_i = pos;
1287   for (int i = start_arg; i < end_arg; i++) {
1288     int arg_index = this_cp->bootstrap_argument_index_at(cp_index, i);
1289     oop arg_oop;
1290     if (must_resolve) {
1291       arg_oop = this_cp->resolve_possibly_cached_constant_at(arg_index, CHECK);
1292     } else {
1293       bool found_it = false;
1294       arg_oop = this_cp->find_cached_constant_at(arg_index, found_it, CHECK);
1295       if (!found_it)  arg_oop = if_not_available();
1296     }
1297     info->obj_at_put(info_i++, arg_oop);
1298   }
1299 }
1300 
1301 oop ConstantPool::string_at_impl(const constantPoolHandle& this_cp, int cp_index, int obj_index, TRAPS) {
1302   // If the string has already been interned, this entry will be non-null
1303   oop str = this_cp->resolved_reference_at(obj_index);
1304   assert(str != Universe::the_null_sentinel(), "");
1305   if (str != nullptr) return str;
1306   Symbol* sym = this_cp->unresolved_string_at(cp_index);
1307   str = StringTable::intern(sym, CHECK_(nullptr));
1308   this_cp->string_at_put(obj_index, str);
1309   assert(java_lang_String::is_instance(str), "must be string");
1310   return str;
1311 }
1312 
1313 
1314 bool ConstantPool::klass_name_at_matches(const InstanceKlass* k, int cp_index) {
1315   // Names are interned, so we can compare Symbol*s directly
1316   Symbol* cp_name = klass_name_at(cp_index);
1317   return (cp_name == k->name());
1318 }
1319 
1320 
1321 // Iterate over symbols and decrement ones which are Symbol*s
1322 // This is done during GC.
1323 // Only decrement the UTF8 symbols. Strings point to
1324 // these symbols but didn't increment the reference count.
1325 void ConstantPool::unreference_symbols() {
1326   for (int index = 1; index < length(); index++) { // Index 0 is unused
1327     constantTag tag = tag_at(index);
1328     if (tag.is_symbol()) {
1329       symbol_at(index)->decrement_refcount();
1330     }
1331   }
1332 }
1333 
1334 
1335 // Compare this constant pool's entry at index1 to the constant pool
1336 // cp2's entry at index2.
1337 bool ConstantPool::compare_entry_to(int index1, const constantPoolHandle& cp2,
1338        int index2) {
1339 
1340   // The error tags are equivalent to non-error tags when comparing
1341   jbyte t1 = tag_at(index1).non_error_value();
1342   jbyte t2 = cp2->tag_at(index2).non_error_value();
1343 
1344   if (t1 != t2) {
1345     // Not the same entry type so there is nothing else to check. Note
1346     // that this style of checking will consider resolved/unresolved
1347     // class pairs as different.
1348     // From the ConstantPool* API point of view, this is correct
1349     // behavior. See VM_RedefineClasses::merge_constant_pools() to see how this
1350     // plays out in the context of ConstantPool* merging.
1351     return false;
1352   }
1353 
1354   switch (t1) {
1355   case JVM_CONSTANT_Class:
1356   {
1357     Klass* k1 = resolved_klass_at(index1);
1358     Klass* k2 = cp2->resolved_klass_at(index2);
1359     if (k1 == k2) {
1360       return true;
1361     }
1362   } break;
1363 
1364   case JVM_CONSTANT_ClassIndex:
1365   {
1366     int recur1 = klass_index_at(index1);
1367     int recur2 = cp2->klass_index_at(index2);
1368     if (compare_entry_to(recur1, cp2, recur2)) {
1369       return true;
1370     }
1371   } break;
1372 
1373   case JVM_CONSTANT_Double:
1374   {
1375     jdouble d1 = double_at(index1);
1376     jdouble d2 = cp2->double_at(index2);
1377     if (d1 == d2) {
1378       return true;
1379     }
1380   } break;
1381 
1382   case JVM_CONSTANT_Fieldref:
1383   case JVM_CONSTANT_InterfaceMethodref:
1384   case JVM_CONSTANT_Methodref:
1385   {
1386     int recur1 = uncached_klass_ref_index_at(index1);
1387     int recur2 = cp2->uncached_klass_ref_index_at(index2);
1388     bool match = compare_entry_to(recur1, cp2, recur2);
1389     if (match) {
1390       recur1 = uncached_name_and_type_ref_index_at(index1);
1391       recur2 = cp2->uncached_name_and_type_ref_index_at(index2);
1392       if (compare_entry_to(recur1, cp2, recur2)) {
1393         return true;
1394       }
1395     }
1396   } break;
1397 
1398   case JVM_CONSTANT_Float:
1399   {
1400     jfloat f1 = float_at(index1);
1401     jfloat f2 = cp2->float_at(index2);
1402     if (f1 == f2) {
1403       return true;
1404     }
1405   } break;
1406 
1407   case JVM_CONSTANT_Integer:
1408   {
1409     jint i1 = int_at(index1);
1410     jint i2 = cp2->int_at(index2);
1411     if (i1 == i2) {
1412       return true;
1413     }
1414   } break;
1415 
1416   case JVM_CONSTANT_Long:
1417   {
1418     jlong l1 = long_at(index1);
1419     jlong l2 = cp2->long_at(index2);
1420     if (l1 == l2) {
1421       return true;
1422     }
1423   } break;
1424 
1425   case JVM_CONSTANT_NameAndType:
1426   {
1427     int recur1 = name_ref_index_at(index1);
1428     int recur2 = cp2->name_ref_index_at(index2);
1429     if (compare_entry_to(recur1, cp2, recur2)) {
1430       recur1 = signature_ref_index_at(index1);
1431       recur2 = cp2->signature_ref_index_at(index2);
1432       if (compare_entry_to(recur1, cp2, recur2)) {
1433         return true;
1434       }
1435     }
1436   } break;
1437 
1438   case JVM_CONSTANT_StringIndex:
1439   {
1440     int recur1 = string_index_at(index1);
1441     int recur2 = cp2->string_index_at(index2);
1442     if (compare_entry_to(recur1, cp2, recur2)) {
1443       return true;
1444     }
1445   } break;
1446 
1447   case JVM_CONSTANT_UnresolvedClass:
1448   {
1449     Symbol* k1 = klass_name_at(index1);
1450     Symbol* k2 = cp2->klass_name_at(index2);
1451     if (k1 == k2) {
1452       return true;
1453     }
1454   } break;
1455 
1456   case JVM_CONSTANT_MethodType:
1457   {
1458     int k1 = method_type_index_at(index1);
1459     int k2 = cp2->method_type_index_at(index2);
1460     if (compare_entry_to(k1, cp2, k2)) {
1461       return true;
1462     }
1463   } break;
1464 
1465   case JVM_CONSTANT_MethodHandle:
1466   {
1467     int k1 = method_handle_ref_kind_at(index1);
1468     int k2 = cp2->method_handle_ref_kind_at(index2);
1469     if (k1 == k2) {
1470       int i1 = method_handle_index_at(index1);
1471       int i2 = cp2->method_handle_index_at(index2);
1472       if (compare_entry_to(i1, cp2, i2)) {
1473         return true;
1474       }
1475     }
1476   } break;
1477 
1478   case JVM_CONSTANT_Dynamic:
1479   {
1480     int k1 = bootstrap_name_and_type_ref_index_at(index1);
1481     int k2 = cp2->bootstrap_name_and_type_ref_index_at(index2);
1482     int i1 = bootstrap_methods_attribute_index(index1);
1483     int i2 = cp2->bootstrap_methods_attribute_index(index2);
1484     bool match_entry = compare_entry_to(k1, cp2, k2);
1485     bool match_operand = compare_operand_to(i1, cp2, i2);
1486     return (match_entry && match_operand);
1487   } break;
1488 
1489   case JVM_CONSTANT_InvokeDynamic:
1490   {
1491     int k1 = bootstrap_name_and_type_ref_index_at(index1);
1492     int k2 = cp2->bootstrap_name_and_type_ref_index_at(index2);
1493     int i1 = bootstrap_methods_attribute_index(index1);
1494     int i2 = cp2->bootstrap_methods_attribute_index(index2);
1495     bool match_entry = compare_entry_to(k1, cp2, k2);
1496     bool match_operand = compare_operand_to(i1, cp2, i2);
1497     return (match_entry && match_operand);
1498   } break;
1499 
1500   case JVM_CONSTANT_String:
1501   {
1502     Symbol* s1 = unresolved_string_at(index1);
1503     Symbol* s2 = cp2->unresolved_string_at(index2);
1504     if (s1 == s2) {
1505       return true;
1506     }
1507   } break;
1508 
1509   case JVM_CONSTANT_Utf8:
1510   {
1511     Symbol* s1 = symbol_at(index1);
1512     Symbol* s2 = cp2->symbol_at(index2);
1513     if (s1 == s2) {
1514       return true;
1515     }
1516   } break;
1517 
1518   // Invalid is used as the tag for the second constant pool entry
1519   // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
1520   // not be seen by itself.
1521   case JVM_CONSTANT_Invalid: // fall through
1522 
1523   default:
1524     ShouldNotReachHere();
1525     break;
1526   }
1527 
1528   return false;
1529 } // end compare_entry_to()
1530 
1531 
1532 // Resize the operands array with delta_len and delta_size.
1533 // Used in RedefineClasses for CP merge.
1534 void ConstantPool::resize_operands(int delta_len, int delta_size, TRAPS) {
1535   int old_len  = operand_array_length(operands());
1536   int new_len  = old_len + delta_len;
1537   int min_len  = (delta_len > 0) ? old_len : new_len;
1538 
1539   int old_size = operands()->length();
1540   int new_size = old_size + delta_size;
1541   int min_size = (delta_size > 0) ? old_size : new_size;
1542 
1543   ClassLoaderData* loader_data = pool_holder()->class_loader_data();
1544   Array<u2>* new_ops = MetadataFactory::new_array<u2>(loader_data, new_size, CHECK);
1545 
1546   // Set index in the resized array for existing elements only
1547   for (int idx = 0; idx < min_len; idx++) {
1548     int offset = operand_offset_at(idx);                       // offset in original array
1549     operand_offset_at_put(new_ops, idx, offset + 2*delta_len); // offset in resized array
1550   }
1551   // Copy the bootstrap specifiers only
1552   Copy::conjoint_memory_atomic(operands()->adr_at(2*old_len),
1553                                new_ops->adr_at(2*new_len),
1554                                (min_size - 2*min_len) * sizeof(u2));
1555   // Explicitly deallocate old operands array.
1556   // Note, it is not needed for 7u backport.
1557   if ( operands() != nullptr) { // the safety check
1558     MetadataFactory::free_array<u2>(loader_data, operands());
1559   }
1560   set_operands(new_ops);
1561 } // end resize_operands()
1562 
1563 
1564 // Extend the operands array with the length and size of the ext_cp operands.
1565 // Used in RedefineClasses for CP merge.
1566 void ConstantPool::extend_operands(const constantPoolHandle& ext_cp, TRAPS) {
1567   int delta_len = operand_array_length(ext_cp->operands());
1568   if (delta_len == 0) {
1569     return; // nothing to do
1570   }
1571   int delta_size = ext_cp->operands()->length();
1572 
1573   assert(delta_len  > 0 && delta_size > 0, "extended operands array must be bigger");
1574 
1575   if (operand_array_length(operands()) == 0) {
1576     ClassLoaderData* loader_data = pool_holder()->class_loader_data();
1577     Array<u2>* new_ops = MetadataFactory::new_array<u2>(loader_data, delta_size, CHECK);
1578     // The first element index defines the offset of second part
1579     operand_offset_at_put(new_ops, 0, 2*delta_len); // offset in new array
1580     set_operands(new_ops);
1581   } else {
1582     resize_operands(delta_len, delta_size, CHECK);
1583   }
1584 
1585 } // end extend_operands()
1586 
1587 
1588 // Shrink the operands array to a smaller array with new_len length.
1589 // Used in RedefineClasses for CP merge.
1590 void ConstantPool::shrink_operands(int new_len, TRAPS) {
1591   int old_len = operand_array_length(operands());
1592   if (new_len == old_len) {
1593     return; // nothing to do
1594   }
1595   assert(new_len < old_len, "shrunken operands array must be smaller");
1596 
1597   int free_base  = operand_next_offset_at(new_len - 1);
1598   int delta_len  = new_len - old_len;
1599   int delta_size = 2*delta_len + free_base - operands()->length();
1600 
1601   resize_operands(delta_len, delta_size, CHECK);
1602 
1603 } // end shrink_operands()
1604 
1605 
1606 void ConstantPool::copy_operands(const constantPoolHandle& from_cp,
1607                                  const constantPoolHandle& to_cp,
1608                                  TRAPS) {
1609 
1610   int from_oplen = operand_array_length(from_cp->operands());
1611   int old_oplen  = operand_array_length(to_cp->operands());
1612   if (from_oplen != 0) {
1613     ClassLoaderData* loader_data = to_cp->pool_holder()->class_loader_data();
1614     // append my operands to the target's operands array
1615     if (old_oplen == 0) {
1616       // Can't just reuse from_cp's operand list because of deallocation issues
1617       int len = from_cp->operands()->length();
1618       Array<u2>* new_ops = MetadataFactory::new_array<u2>(loader_data, len, CHECK);
1619       Copy::conjoint_memory_atomic(
1620           from_cp->operands()->adr_at(0), new_ops->adr_at(0), len * sizeof(u2));
1621       to_cp->set_operands(new_ops);
1622     } else {
1623       int old_len  = to_cp->operands()->length();
1624       int from_len = from_cp->operands()->length();
1625       int old_off  = old_oplen * sizeof(u2);
1626       int from_off = from_oplen * sizeof(u2);
1627       // Use the metaspace for the destination constant pool
1628       Array<u2>* new_operands = MetadataFactory::new_array<u2>(loader_data, old_len + from_len, CHECK);
1629       int fillp = 0, len = 0;
1630       // first part of dest
1631       Copy::conjoint_memory_atomic(to_cp->operands()->adr_at(0),
1632                                    new_operands->adr_at(fillp),
1633                                    (len = old_off) * sizeof(u2));
1634       fillp += len;
1635       // first part of src
1636       Copy::conjoint_memory_atomic(from_cp->operands()->adr_at(0),
1637                                    new_operands->adr_at(fillp),
1638                                    (len = from_off) * sizeof(u2));
1639       fillp += len;
1640       // second part of dest
1641       Copy::conjoint_memory_atomic(to_cp->operands()->adr_at(old_off),
1642                                    new_operands->adr_at(fillp),
1643                                    (len = old_len - old_off) * sizeof(u2));
1644       fillp += len;
1645       // second part of src
1646       Copy::conjoint_memory_atomic(from_cp->operands()->adr_at(from_off),
1647                                    new_operands->adr_at(fillp),
1648                                    (len = from_len - from_off) * sizeof(u2));
1649       fillp += len;
1650       assert(fillp == new_operands->length(), "");
1651 
1652       // Adjust indexes in the first part of the copied operands array.
1653       for (int j = 0; j < from_oplen; j++) {
1654         int offset = operand_offset_at(new_operands, old_oplen + j);
1655         assert(offset == operand_offset_at(from_cp->operands(), j), "correct copy");
1656         offset += old_len;  // every new tuple is preceded by old_len extra u2's
1657         operand_offset_at_put(new_operands, old_oplen + j, offset);
1658       }
1659 
1660       // replace target operands array with combined array
1661       to_cp->set_operands(new_operands);
1662     }
1663   }
1664 } // end copy_operands()
1665 
1666 
1667 // Copy this constant pool's entries at start_i to end_i (inclusive)
1668 // to the constant pool to_cp's entries starting at to_i. A total of
1669 // (end_i - start_i) + 1 entries are copied.
1670 void ConstantPool::copy_cp_to_impl(const constantPoolHandle& from_cp, int start_i, int end_i,
1671        const constantPoolHandle& to_cp, int to_i, TRAPS) {
1672 
1673 
1674   int dest_cpi = to_i;  // leave original alone for debug purposes
1675 
1676   for (int src_cpi = start_i; src_cpi <= end_i; /* see loop bottom */ ) {
1677     copy_entry_to(from_cp, src_cpi, to_cp, dest_cpi);
1678 
1679     switch (from_cp->tag_at(src_cpi).value()) {
1680     case JVM_CONSTANT_Double:
1681     case JVM_CONSTANT_Long:
1682       // double and long take two constant pool entries
1683       src_cpi += 2;
1684       dest_cpi += 2;
1685       break;
1686 
1687     default:
1688       // all others take one constant pool entry
1689       src_cpi++;
1690       dest_cpi++;
1691       break;
1692     }
1693   }
1694   copy_operands(from_cp, to_cp, CHECK);
1695 
1696 } // end copy_cp_to_impl()
1697 
1698 
1699 // Copy this constant pool's entry at from_i to the constant pool
1700 // to_cp's entry at to_i.
1701 void ConstantPool::copy_entry_to(const constantPoolHandle& from_cp, int from_i,
1702                                         const constantPoolHandle& to_cp, int to_i) {
1703 
1704   int tag = from_cp->tag_at(from_i).value();
1705   switch (tag) {
1706   case JVM_CONSTANT_ClassIndex:
1707   {
1708     jint ki = from_cp->klass_index_at(from_i);
1709     to_cp->klass_index_at_put(to_i, ki);
1710   } break;
1711 
1712   case JVM_CONSTANT_Double:
1713   {
1714     jdouble d = from_cp->double_at(from_i);
1715     to_cp->double_at_put(to_i, d);
1716     // double takes two constant pool entries so init second entry's tag
1717     to_cp->tag_at_put(to_i + 1, JVM_CONSTANT_Invalid);
1718   } break;
1719 
1720   case JVM_CONSTANT_Fieldref:
1721   {
1722     int class_index = from_cp->uncached_klass_ref_index_at(from_i);
1723     int name_and_type_index = from_cp->uncached_name_and_type_ref_index_at(from_i);
1724     to_cp->field_at_put(to_i, class_index, name_and_type_index);
1725   } break;
1726 
1727   case JVM_CONSTANT_Float:
1728   {
1729     jfloat f = from_cp->float_at(from_i);
1730     to_cp->float_at_put(to_i, f);
1731   } break;
1732 
1733   case JVM_CONSTANT_Integer:
1734   {
1735     jint i = from_cp->int_at(from_i);
1736     to_cp->int_at_put(to_i, i);
1737   } break;
1738 
1739   case JVM_CONSTANT_InterfaceMethodref:
1740   {
1741     int class_index = from_cp->uncached_klass_ref_index_at(from_i);
1742     int name_and_type_index = from_cp->uncached_name_and_type_ref_index_at(from_i);
1743     to_cp->interface_method_at_put(to_i, class_index, name_and_type_index);
1744   } break;
1745 
1746   case JVM_CONSTANT_Long:
1747   {
1748     jlong l = from_cp->long_at(from_i);
1749     to_cp->long_at_put(to_i, l);
1750     // long takes two constant pool entries so init second entry's tag
1751     to_cp->tag_at_put(to_i + 1, JVM_CONSTANT_Invalid);
1752   } break;
1753 
1754   case JVM_CONSTANT_Methodref:
1755   {
1756     int class_index = from_cp->uncached_klass_ref_index_at(from_i);
1757     int name_and_type_index = from_cp->uncached_name_and_type_ref_index_at(from_i);
1758     to_cp->method_at_put(to_i, class_index, name_and_type_index);
1759   } break;
1760 
1761   case JVM_CONSTANT_NameAndType:
1762   {
1763     int name_ref_index = from_cp->name_ref_index_at(from_i);
1764     int signature_ref_index = from_cp->signature_ref_index_at(from_i);
1765     to_cp->name_and_type_at_put(to_i, name_ref_index, signature_ref_index);
1766   } break;
1767 
1768   case JVM_CONSTANT_StringIndex:
1769   {
1770     jint si = from_cp->string_index_at(from_i);
1771     to_cp->string_index_at_put(to_i, si);
1772   } break;
1773 
1774   case JVM_CONSTANT_Class:
1775   case JVM_CONSTANT_UnresolvedClass:
1776   case JVM_CONSTANT_UnresolvedClassInError:
1777   {
1778     // Revert to JVM_CONSTANT_ClassIndex
1779     int name_index = from_cp->klass_slot_at(from_i).name_index();
1780     assert(from_cp->tag_at(name_index).is_symbol(), "sanity");
1781     to_cp->klass_index_at_put(to_i, name_index);
1782   } break;
1783 
1784   case JVM_CONSTANT_String:
1785   {
1786     Symbol* s = from_cp->unresolved_string_at(from_i);
1787     to_cp->unresolved_string_at_put(to_i, s);
1788   } break;
1789 
1790   case JVM_CONSTANT_Utf8:
1791   {
1792     Symbol* s = from_cp->symbol_at(from_i);
1793     // Need to increase refcount, the old one will be thrown away and deferenced
1794     s->increment_refcount();
1795     to_cp->symbol_at_put(to_i, s);
1796   } break;
1797 
1798   case JVM_CONSTANT_MethodType:
1799   case JVM_CONSTANT_MethodTypeInError:
1800   {
1801     jint k = from_cp->method_type_index_at(from_i);
1802     to_cp->method_type_index_at_put(to_i, k);
1803   } break;
1804 
1805   case JVM_CONSTANT_MethodHandle:
1806   case JVM_CONSTANT_MethodHandleInError:
1807   {
1808     int k1 = from_cp->method_handle_ref_kind_at(from_i);
1809     int k2 = from_cp->method_handle_index_at(from_i);
1810     to_cp->method_handle_index_at_put(to_i, k1, k2);
1811   } break;
1812 
1813   case JVM_CONSTANT_Dynamic:
1814   case JVM_CONSTANT_DynamicInError:
1815   {
1816     int k1 = from_cp->bootstrap_methods_attribute_index(from_i);
1817     int k2 = from_cp->bootstrap_name_and_type_ref_index_at(from_i);
1818     k1 += operand_array_length(to_cp->operands());  // to_cp might already have operands
1819     to_cp->dynamic_constant_at_put(to_i, k1, k2);
1820   } break;
1821 
1822   case JVM_CONSTANT_InvokeDynamic:
1823   {
1824     int k1 = from_cp->bootstrap_methods_attribute_index(from_i);
1825     int k2 = from_cp->bootstrap_name_and_type_ref_index_at(from_i);
1826     k1 += operand_array_length(to_cp->operands());  // to_cp might already have operands
1827     to_cp->invoke_dynamic_at_put(to_i, k1, k2);
1828   } break;
1829 
1830   // Invalid is used as the tag for the second constant pool entry
1831   // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
1832   // not be seen by itself.
1833   case JVM_CONSTANT_Invalid: // fall through
1834 
1835   default:
1836   {
1837     ShouldNotReachHere();
1838   } break;
1839   }
1840 } // end copy_entry_to()
1841 
1842 // Search constant pool search_cp for an entry that matches this
1843 // constant pool's entry at pattern_i. Returns the index of a
1844 // matching entry or zero (0) if there is no matching entry.
1845 int ConstantPool::find_matching_entry(int pattern_i,
1846       const constantPoolHandle& search_cp) {
1847 
1848   // index zero (0) is not used
1849   for (int i = 1; i < search_cp->length(); i++) {
1850     bool found = compare_entry_to(pattern_i, search_cp, i);
1851     if (found) {
1852       return i;
1853     }
1854   }
1855 
1856   return 0;  // entry not found; return unused index zero (0)
1857 } // end find_matching_entry()
1858 
1859 
1860 // Compare this constant pool's bootstrap specifier at idx1 to the constant pool
1861 // cp2's bootstrap specifier at idx2.
1862 bool ConstantPool::compare_operand_to(int idx1, const constantPoolHandle& cp2, int idx2) {
1863   int k1 = operand_bootstrap_method_ref_index_at(idx1);
1864   int k2 = cp2->operand_bootstrap_method_ref_index_at(idx2);
1865   bool match = compare_entry_to(k1, cp2, k2);
1866 
1867   if (!match) {
1868     return false;
1869   }
1870   int argc = operand_argument_count_at(idx1);
1871   if (argc == cp2->operand_argument_count_at(idx2)) {
1872     for (int j = 0; j < argc; j++) {
1873       k1 = operand_argument_index_at(idx1, j);
1874       k2 = cp2->operand_argument_index_at(idx2, j);
1875       match = compare_entry_to(k1, cp2, k2);
1876       if (!match) {
1877         return false;
1878       }
1879     }
1880     return true;           // got through loop; all elements equal
1881   }
1882   return false;
1883 } // end compare_operand_to()
1884 
1885 // Search constant pool search_cp for a bootstrap specifier that matches
1886 // this constant pool's bootstrap specifier data at pattern_i index.
1887 // Return the index of a matching bootstrap attribute record or (-1) if there is no match.
1888 int ConstantPool::find_matching_operand(int pattern_i,
1889                     const constantPoolHandle& search_cp, int search_len) {
1890   for (int i = 0; i < search_len; i++) {
1891     bool found = compare_operand_to(pattern_i, search_cp, i);
1892     if (found) {
1893       return i;
1894     }
1895   }
1896   return -1;  // bootstrap specifier data not found; return unused index (-1)
1897 } // end find_matching_operand()
1898 
1899 
1900 #ifndef PRODUCT
1901 
1902 const char* ConstantPool::printable_name_at(int cp_index) {
1903 
1904   constantTag tag = tag_at(cp_index);
1905 
1906   if (tag.is_string()) {
1907     return string_at_noresolve(cp_index);
1908   } else if (tag.is_klass() || tag.is_unresolved_klass()) {
1909     return klass_name_at(cp_index)->as_C_string();
1910   } else if (tag.is_symbol()) {
1911     return symbol_at(cp_index)->as_C_string();
1912   }
1913   return "";
1914 }
1915 
1916 #endif // PRODUCT
1917 
1918 
1919 // JVMTI GetConstantPool support
1920 
1921 // For debugging of constant pool
1922 const bool debug_cpool = false;
1923 
1924 #define DBG(code) do { if (debug_cpool) { (code); } } while(0)
1925 
1926 static void print_cpool_bytes(jint cnt, u1 *bytes) {
1927   const char* WARN_MSG = "Must not be such entry!";
1928   jint size = 0;
1929   u2   idx1, idx2;
1930 
1931   for (jint idx = 1; idx < cnt; idx++) {
1932     jint ent_size = 0;
1933     u1   tag  = *bytes++;
1934     size++;                       // count tag
1935 
1936     printf("const #%03d, tag: %02d ", idx, tag);
1937     switch(tag) {
1938       case JVM_CONSTANT_Invalid: {
1939         printf("Invalid");
1940         break;
1941       }
1942       case JVM_CONSTANT_Unicode: {
1943         printf("Unicode      %s", WARN_MSG);
1944         break;
1945       }
1946       case JVM_CONSTANT_Utf8: {
1947         u2 len = Bytes::get_Java_u2(bytes);
1948         char str[128];
1949         if (len > 127) {
1950            len = 127;
1951         }
1952         strncpy(str, (char *) (bytes+2), len);
1953         str[len] = '\0';
1954         printf("Utf8          \"%s\"", str);
1955         ent_size = 2 + len;
1956         break;
1957       }
1958       case JVM_CONSTANT_Integer: {
1959         u4 val = Bytes::get_Java_u4(bytes);
1960         printf("int          %d", *(int *) &val);
1961         ent_size = 4;
1962         break;
1963       }
1964       case JVM_CONSTANT_Float: {
1965         u4 val = Bytes::get_Java_u4(bytes);
1966         printf("float        %5.3ff", *(float *) &val);
1967         ent_size = 4;
1968         break;
1969       }
1970       case JVM_CONSTANT_Long: {
1971         u8 val = Bytes::get_Java_u8(bytes);
1972         printf("long         " INT64_FORMAT, (int64_t) *(jlong *) &val);
1973         ent_size = 8;
1974         idx++; // Long takes two cpool slots
1975         break;
1976       }
1977       case JVM_CONSTANT_Double: {
1978         u8 val = Bytes::get_Java_u8(bytes);
1979         printf("double       %5.3fd", *(jdouble *)&val);
1980         ent_size = 8;
1981         idx++; // Double takes two cpool slots
1982         break;
1983       }
1984       case JVM_CONSTANT_Class: {
1985         idx1 = Bytes::get_Java_u2(bytes);
1986         printf("class        #%03d", idx1);
1987         ent_size = 2;
1988         break;
1989       }
1990       case (JVM_CONSTANT_Class | JVM_CONSTANT_QDescBit): {
1991         idx1 = Bytes::get_Java_u2(bytes);
1992         printf("qclass        #%03d", idx1);
1993         ent_size = 2;
1994         break;
1995       }
1996       case JVM_CONSTANT_String: {
1997         idx1 = Bytes::get_Java_u2(bytes);
1998         printf("String       #%03d", idx1);
1999         ent_size = 2;
2000         break;
2001       }
2002       case JVM_CONSTANT_Fieldref: {
2003         idx1 = Bytes::get_Java_u2(bytes);
2004         idx2 = Bytes::get_Java_u2(bytes+2);
2005         printf("Field        #%03d, #%03d", (int) idx1, (int) idx2);
2006         ent_size = 4;
2007         break;
2008       }
2009       case JVM_CONSTANT_Methodref: {
2010         idx1 = Bytes::get_Java_u2(bytes);
2011         idx2 = Bytes::get_Java_u2(bytes+2);
2012         printf("Method       #%03d, #%03d", idx1, idx2);
2013         ent_size = 4;
2014         break;
2015       }
2016       case JVM_CONSTANT_InterfaceMethodref: {
2017         idx1 = Bytes::get_Java_u2(bytes);
2018         idx2 = Bytes::get_Java_u2(bytes+2);
2019         printf("InterfMethod #%03d, #%03d", idx1, idx2);
2020         ent_size = 4;
2021         break;
2022       }
2023       case JVM_CONSTANT_NameAndType: {
2024         idx1 = Bytes::get_Java_u2(bytes);
2025         idx2 = Bytes::get_Java_u2(bytes+2);
2026         printf("NameAndType  #%03d, #%03d", idx1, idx2);
2027         ent_size = 4;
2028         break;
2029       }
2030       case JVM_CONSTANT_ClassIndex: {
2031         printf("ClassIndex  %s", WARN_MSG);
2032         break;
2033       }
2034       case JVM_CONSTANT_UnresolvedClass: {
2035         printf("UnresolvedClass: %s", WARN_MSG);
2036         break;
2037       }
2038       case (JVM_CONSTANT_UnresolvedClass | JVM_CONSTANT_QDescBit): {
2039         printf("UnresolvedQClass: %s", WARN_MSG);
2040         break;
2041       }
2042       case JVM_CONSTANT_UnresolvedClassInError: {
2043         printf("UnresolvedClassInErr: %s", WARN_MSG);
2044         break;
2045       }
2046       case JVM_CONSTANT_StringIndex: {
2047         printf("StringIndex: %s", WARN_MSG);
2048         break;
2049       }
2050     }
2051     printf(";\n");
2052     bytes += ent_size;
2053     size  += ent_size;
2054   }
2055   printf("Cpool size: %d\n", size);
2056   fflush(0);
2057   return;
2058 } /* end print_cpool_bytes */
2059 
2060 
2061 // Returns size of constant pool entry.
2062 jint ConstantPool::cpool_entry_size(jint idx) {
2063   switch(tag_at(idx).value()) {
2064     case JVM_CONSTANT_Invalid:
2065     case JVM_CONSTANT_Unicode:
2066       return 1;
2067 
2068     case JVM_CONSTANT_Utf8:
2069       return 3 + symbol_at(idx)->utf8_length();
2070 
2071     case JVM_CONSTANT_Class:
2072     case JVM_CONSTANT_String:
2073     case JVM_CONSTANT_ClassIndex:
2074     case JVM_CONSTANT_UnresolvedClass:
2075     case JVM_CONSTANT_UnresolvedClassInError:
2076     case JVM_CONSTANT_StringIndex:
2077     case JVM_CONSTANT_MethodType:
2078     case JVM_CONSTANT_MethodTypeInError:
2079       return 3;
2080 
2081     case JVM_CONSTANT_MethodHandle:
2082     case JVM_CONSTANT_MethodHandleInError:
2083       return 4; //tag, ref_kind, ref_index
2084 
2085     case JVM_CONSTANT_Integer:
2086     case JVM_CONSTANT_Float:
2087     case JVM_CONSTANT_Fieldref:
2088     case JVM_CONSTANT_Methodref:
2089     case JVM_CONSTANT_InterfaceMethodref:
2090     case JVM_CONSTANT_NameAndType:
2091       return 5;
2092 
2093     case JVM_CONSTANT_Dynamic:
2094     case JVM_CONSTANT_DynamicInError:
2095     case JVM_CONSTANT_InvokeDynamic:
2096       // u1 tag, u2 bsm, u2 nt
2097       return 5;
2098 
2099     case JVM_CONSTANT_Long:
2100     case JVM_CONSTANT_Double:
2101       return 9;
2102   }
2103   assert(false, "cpool_entry_size: Invalid constant pool entry tag");
2104   return 1;
2105 } /* end cpool_entry_size */
2106 
2107 
2108 // SymbolHash is used to find a constant pool index from a string.
2109 // This function fills in SymbolHashs, one for utf8s and one for
2110 // class names, returns size of the cpool raw bytes.
2111 jint ConstantPool::hash_entries_to(SymbolHash *symmap,
2112                                    SymbolHash *classmap) {
2113   jint size = 0;
2114 
2115   for (u2 idx = 1; idx < length(); idx++) {
2116     u2 tag = tag_at(idx).value();
2117     size += cpool_entry_size(idx);
2118 
2119     switch(tag) {
2120       case JVM_CONSTANT_Utf8: {
2121         Symbol* sym = symbol_at(idx);
2122         symmap->add_if_absent(sym, idx);
2123         DBG(printf("adding symbol entry %s = %d\n", sym->as_utf8(), idx));
2124         break;
2125       }
2126       case JVM_CONSTANT_Class:
2127       case JVM_CONSTANT_UnresolvedClass:
2128       case JVM_CONSTANT_UnresolvedClassInError: {
2129         Symbol* sym = klass_name_at(idx);
2130         classmap->add_if_absent(sym, idx);
2131         DBG(printf("adding class entry %s = %d\n", sym->as_utf8(), idx));
2132         break;
2133       }
2134       case JVM_CONSTANT_Long:
2135       case JVM_CONSTANT_Double: {
2136         idx++; // Both Long and Double take two cpool slots
2137         break;
2138       }
2139     }
2140   }
2141   return size;
2142 } /* end hash_utf8_entries_to */
2143 
2144 
2145 // Copy cpool bytes.
2146 // Returns:
2147 //    0, in case of OutOfMemoryError
2148 //   -1, in case of internal error
2149 //  > 0, count of the raw cpool bytes that have been copied
2150 int ConstantPool::copy_cpool_bytes(int cpool_size,
2151                                    SymbolHash* tbl,
2152                                    unsigned char *bytes) {
2153   u2   idx1, idx2;
2154   jint size  = 0;
2155   jint cnt   = length();
2156   unsigned char *start_bytes = bytes;
2157 
2158   for (jint idx = 1; idx < cnt; idx++) {
2159     u1   tag      = tag_at(idx).value();
2160     jint ent_size = cpool_entry_size(idx);
2161 
2162     assert(size + ent_size <= cpool_size, "Size mismatch");
2163 
2164     *bytes = tag;
2165     DBG(printf("#%03hd tag=%03hd, ", (short)idx, (short)tag));
2166     switch(tag) {
2167       case JVM_CONSTANT_Invalid: {
2168         DBG(printf("JVM_CONSTANT_Invalid"));
2169         break;
2170       }
2171       case JVM_CONSTANT_Unicode: {
2172         assert(false, "Wrong constant pool tag: JVM_CONSTANT_Unicode");
2173         DBG(printf("JVM_CONSTANT_Unicode"));
2174         break;
2175       }
2176       case JVM_CONSTANT_Utf8: {
2177         Symbol* sym = symbol_at(idx);
2178         char*     str = sym->as_utf8();
2179         // Warning! It's crashing on x86 with len = sym->utf8_length()
2180         int       len = (int) strlen(str);
2181         Bytes::put_Java_u2((address) (bytes+1), (u2) len);
2182         for (int i = 0; i < len; i++) {
2183             bytes[3+i] = (u1) str[i];
2184         }
2185         DBG(printf("JVM_CONSTANT_Utf8: %s ", str));
2186         break;
2187       }
2188       case JVM_CONSTANT_Integer: {
2189         jint val = int_at(idx);
2190         Bytes::put_Java_u4((address) (bytes+1), *(u4*)&val);
2191         break;
2192       }
2193       case JVM_CONSTANT_Float: {
2194         jfloat val = float_at(idx);
2195         Bytes::put_Java_u4((address) (bytes+1), *(u4*)&val);
2196         break;
2197       }
2198       case JVM_CONSTANT_Long: {
2199         jlong val = long_at(idx);
2200         Bytes::put_Java_u8((address) (bytes+1), *(u8*)&val);
2201         idx++;             // Long takes two cpool slots
2202         break;
2203       }
2204       case JVM_CONSTANT_Double: {
2205         jdouble val = double_at(idx);
2206         Bytes::put_Java_u8((address) (bytes+1), *(u8*)&val);
2207         idx++;             // Double takes two cpool slots
2208         break;
2209       }
2210       case JVM_CONSTANT_Class:
2211       case JVM_CONSTANT_UnresolvedClass:
2212       case JVM_CONSTANT_UnresolvedClassInError: {
2213         *bytes = JVM_CONSTANT_Class;
2214         Symbol* sym = klass_name_at(idx);
2215         idx1 = tbl->symbol_to_value(sym);
2216         assert(idx1 != 0, "Have not found a hashtable entry");
2217         Bytes::put_Java_u2((address) (bytes+1), idx1);
2218         DBG(printf("JVM_CONSTANT_Class: idx=#%03hd, %s", idx1, sym->as_utf8()));
2219         break;
2220       }
2221       case JVM_CONSTANT_String: {
2222         *bytes = JVM_CONSTANT_String;
2223         Symbol* sym = unresolved_string_at(idx);
2224         idx1 = tbl->symbol_to_value(sym);
2225         assert(idx1 != 0, "Have not found a hashtable entry");
2226         Bytes::put_Java_u2((address) (bytes+1), idx1);
2227         DBG(printf("JVM_CONSTANT_String: idx=#%03hd, %s", idx1, sym->as_utf8()));
2228         break;
2229       }
2230       case JVM_CONSTANT_Fieldref:
2231       case JVM_CONSTANT_Methodref:
2232       case JVM_CONSTANT_InterfaceMethodref: {
2233         idx1 = uncached_klass_ref_index_at(idx);
2234         idx2 = uncached_name_and_type_ref_index_at(idx);
2235         Bytes::put_Java_u2((address) (bytes+1), idx1);
2236         Bytes::put_Java_u2((address) (bytes+3), idx2);
2237         DBG(printf("JVM_CONSTANT_Methodref: %hd %hd", idx1, idx2));
2238         break;
2239       }
2240       case JVM_CONSTANT_NameAndType: {
2241         idx1 = name_ref_index_at(idx);
2242         idx2 = signature_ref_index_at(idx);
2243         Bytes::put_Java_u2((address) (bytes+1), idx1);
2244         Bytes::put_Java_u2((address) (bytes+3), idx2);
2245         DBG(printf("JVM_CONSTANT_NameAndType: %hd %hd", idx1, idx2));
2246         break;
2247       }
2248       case JVM_CONSTANT_ClassIndex: {
2249         *bytes = JVM_CONSTANT_Class;
2250         idx1 = checked_cast<u2>(klass_index_at(idx));
2251         Bytes::put_Java_u2((address) (bytes+1), idx1);
2252         DBG(printf("JVM_CONSTANT_ClassIndex: %hd", idx1));
2253         break;
2254       }
2255       case JVM_CONSTANT_StringIndex: {
2256         *bytes = JVM_CONSTANT_String;
2257         idx1 = checked_cast<u2>(string_index_at(idx));
2258         Bytes::put_Java_u2((address) (bytes+1), idx1);
2259         DBG(printf("JVM_CONSTANT_StringIndex: %hd", idx1));
2260         break;
2261       }
2262       case JVM_CONSTANT_MethodHandle:
2263       case JVM_CONSTANT_MethodHandleInError: {
2264         *bytes = JVM_CONSTANT_MethodHandle;
2265         int kind = method_handle_ref_kind_at(idx);
2266         idx1 = checked_cast<u2>(method_handle_index_at(idx));
2267         *(bytes+1) = (unsigned char) kind;
2268         Bytes::put_Java_u2((address) (bytes+2), idx1);
2269         DBG(printf("JVM_CONSTANT_MethodHandle: %d %hd", kind, idx1));
2270         break;
2271       }
2272       case JVM_CONSTANT_MethodType:
2273       case JVM_CONSTANT_MethodTypeInError: {
2274         *bytes = JVM_CONSTANT_MethodType;
2275         idx1 = checked_cast<u2>(method_type_index_at(idx));
2276         Bytes::put_Java_u2((address) (bytes+1), idx1);
2277         DBG(printf("JVM_CONSTANT_MethodType: %hd", idx1));
2278         break;
2279       }
2280       case JVM_CONSTANT_Dynamic:
2281       case JVM_CONSTANT_DynamicInError: {
2282         *bytes = tag;
2283         idx1 = extract_low_short_from_int(*int_at_addr(idx));
2284         idx2 = extract_high_short_from_int(*int_at_addr(idx));
2285         assert(idx2 == bootstrap_name_and_type_ref_index_at(idx), "correct half of u4");
2286         Bytes::put_Java_u2((address) (bytes+1), idx1);
2287         Bytes::put_Java_u2((address) (bytes+3), idx2);
2288         DBG(printf("JVM_CONSTANT_Dynamic: %hd %hd", idx1, idx2));
2289         break;
2290       }
2291       case JVM_CONSTANT_InvokeDynamic: {
2292         *bytes = tag;
2293         idx1 = extract_low_short_from_int(*int_at_addr(idx));
2294         idx2 = extract_high_short_from_int(*int_at_addr(idx));
2295         assert(idx2 == bootstrap_name_and_type_ref_index_at(idx), "correct half of u4");
2296         Bytes::put_Java_u2((address) (bytes+1), idx1);
2297         Bytes::put_Java_u2((address) (bytes+3), idx2);
2298         DBG(printf("JVM_CONSTANT_InvokeDynamic: %hd %hd", idx1, idx2));
2299         break;
2300       }
2301     }
2302     DBG(printf("\n"));
2303     bytes += ent_size;
2304     size  += ent_size;
2305   }
2306   assert(size == cpool_size, "Size mismatch");
2307 
2308   // Keep temporarily for debugging until it's stable.
2309   DBG(print_cpool_bytes(cnt, start_bytes));
2310   return (int)(bytes - start_bytes);
2311 } /* end copy_cpool_bytes */
2312 
2313 #undef DBG
2314 
2315 bool ConstantPool::is_maybe_on_stack() const {
2316   // This method uses the similar logic as nmethod::is_maybe_on_stack()
2317   if (!Continuations::enabled()) {
2318     return false;
2319   }
2320 
2321   // If the condition below is true, it means that the nmethod was found to
2322   // be alive the previous completed marking cycle.
2323   return cache()->gc_epoch() >= CodeCache::previous_completed_gc_marking_cycle();
2324 }
2325 
2326 // For redefinition, if any methods found in loom stack chunks, the gc_epoch is
2327 // recorded in their constant pool cache. The on_stack-ness of the constant pool controls whether
2328 // memory for the method is reclaimed.
2329 bool ConstantPool::on_stack() const {
2330   if ((_flags &_on_stack) != 0) {
2331     return true;
2332   }
2333 
2334   if (_cache == nullptr) {
2335     return false;
2336   }
2337 
2338   return is_maybe_on_stack();
2339 }
2340 
2341 void ConstantPool::set_on_stack(const bool value) {
2342   if (value) {
2343     // Only record if it's not already set.
2344     if (!on_stack()) {
2345       assert(!is_shared(), "should always be set for shared constant pools");
2346       _flags |= _on_stack;
2347       MetadataOnStackMark::record(this);
2348     }
2349   } else {
2350     // Clearing is done single-threadedly.
2351     if (!is_shared()) {
2352       _flags &= (u2)(~_on_stack);
2353     }
2354   }
2355 }
2356 
2357 // Printing
2358 
2359 void ConstantPool::print_on(outputStream* st) const {
2360   assert(is_constantPool(), "must be constantPool");
2361   st->print_cr("%s", internal_name());
2362   if (flags() != 0) {
2363     st->print(" - flags: 0x%x", flags());
2364     if (has_preresolution()) st->print(" has_preresolution");
2365     if (on_stack()) st->print(" on_stack");
2366     st->cr();
2367   }
2368   if (pool_holder() != nullptr) {
2369     st->print_cr(" - holder: " PTR_FORMAT, p2i(pool_holder()));
2370   }
2371   st->print_cr(" - cache: " PTR_FORMAT, p2i(cache()));
2372   st->print_cr(" - resolved_references: " PTR_FORMAT, p2i(resolved_references_or_null()));
2373   st->print_cr(" - reference_map: " PTR_FORMAT, p2i(reference_map()));
2374   st->print_cr(" - resolved_klasses: " PTR_FORMAT, p2i(resolved_klasses()));
2375   st->print_cr(" - cp length: %d", length());
2376 
2377   for (int index = 1; index < length(); index++) {      // Index 0 is unused
2378     ((ConstantPool*)this)->print_entry_on(index, st);
2379     switch (tag_at(index).value()) {
2380       case JVM_CONSTANT_Long :
2381       case JVM_CONSTANT_Double :
2382         index++;   // Skip entry following eigth-byte constant
2383     }
2384 
2385   }
2386   st->cr();
2387 }
2388 
2389 // Print one constant pool entry
2390 void ConstantPool::print_entry_on(const int cp_index, outputStream* st) {
2391   EXCEPTION_MARK;
2392   st->print(" - %3d : ", cp_index);
2393   tag_at(cp_index).print_on(st);
2394   st->print(" : ");
2395   switch (tag_at(cp_index).value()) {
2396     case JVM_CONSTANT_Class :
2397       { Klass* k = klass_at(cp_index, CATCH);
2398         guarantee(k != nullptr, "need klass");
2399         k->print_value_on(st);
2400         st->print(" {" PTR_FORMAT "}", p2i(k));
2401       }
2402       break;
2403     case JVM_CONSTANT_Fieldref :
2404     case JVM_CONSTANT_Methodref :
2405     case JVM_CONSTANT_InterfaceMethodref :
2406       st->print("klass_index=%d", uncached_klass_ref_index_at(cp_index));
2407       st->print(" name_and_type_index=%d", uncached_name_and_type_ref_index_at(cp_index));
2408       break;
2409     case JVM_CONSTANT_String :
2410       unresolved_string_at(cp_index)->print_value_on(st);
2411       break;
2412     case JVM_CONSTANT_Integer :
2413       st->print("%d", int_at(cp_index));
2414       break;
2415     case JVM_CONSTANT_Float :
2416       st->print("%f", float_at(cp_index));
2417       break;
2418     case JVM_CONSTANT_Long :
2419       st->print_jlong(long_at(cp_index));
2420       break;
2421     case JVM_CONSTANT_Double :
2422       st->print("%lf", double_at(cp_index));
2423       break;
2424     case JVM_CONSTANT_NameAndType :
2425       st->print("name_index=%d", name_ref_index_at(cp_index));
2426       st->print(" signature_index=%d", signature_ref_index_at(cp_index));
2427       break;
2428     case JVM_CONSTANT_Utf8 :
2429       symbol_at(cp_index)->print_value_on(st);
2430       break;
2431     case JVM_CONSTANT_ClassIndex: {
2432         int name_index = *int_at_addr(cp_index);
2433         st->print("klass_index=%d ", name_index);
2434         symbol_at(name_index)->print_value_on(st);
2435       }
2436       break;
2437     case JVM_CONSTANT_UnresolvedClass :               // fall-through
2438     case JVM_CONSTANT_UnresolvedClassInError: {
2439         CPKlassSlot kslot = klass_slot_at(cp_index);
2440         int resolved_klass_index = kslot.resolved_klass_index();
2441         int name_index = kslot.name_index();
2442         assert(tag_at(name_index).is_symbol(), "sanity");
2443         symbol_at(name_index)->print_value_on(st);
2444       }
2445       break;
2446     case JVM_CONSTANT_MethodHandle :
2447     case JVM_CONSTANT_MethodHandleInError :
2448       st->print("ref_kind=%d", method_handle_ref_kind_at(cp_index));
2449       st->print(" ref_index=%d", method_handle_index_at(cp_index));
2450       break;
2451     case JVM_CONSTANT_MethodType :
2452     case JVM_CONSTANT_MethodTypeInError :
2453       st->print("signature_index=%d", method_type_index_at(cp_index));
2454       break;
2455     case JVM_CONSTANT_Dynamic :
2456     case JVM_CONSTANT_DynamicInError :
2457       {
2458         st->print("bootstrap_method_index=%d", bootstrap_method_ref_index_at(cp_index));
2459         st->print(" type_index=%d", bootstrap_name_and_type_ref_index_at(cp_index));
2460         int argc = bootstrap_argument_count_at(cp_index);
2461         if (argc > 0) {
2462           for (int arg_i = 0; arg_i < argc; arg_i++) {
2463             int arg = bootstrap_argument_index_at(cp_index, arg_i);
2464             st->print((arg_i == 0 ? " arguments={%d" : ", %d"), arg);
2465           }
2466           st->print("}");
2467         }
2468       }
2469       break;
2470     case JVM_CONSTANT_InvokeDynamic :
2471       {
2472         st->print("bootstrap_method_index=%d", bootstrap_method_ref_index_at(cp_index));
2473         st->print(" name_and_type_index=%d", bootstrap_name_and_type_ref_index_at(cp_index));
2474         int argc = bootstrap_argument_count_at(cp_index);
2475         if (argc > 0) {
2476           for (int arg_i = 0; arg_i < argc; arg_i++) {
2477             int arg = bootstrap_argument_index_at(cp_index, arg_i);
2478             st->print((arg_i == 0 ? " arguments={%d" : ", %d"), arg);
2479           }
2480           st->print("}");
2481         }
2482       }
2483       break;
2484     default:
2485       ShouldNotReachHere();
2486       break;
2487   }
2488   st->cr();
2489 }
2490 
2491 void ConstantPool::print_value_on(outputStream* st) const {
2492   assert(is_constantPool(), "must be constantPool");
2493   st->print("constant pool [%d]", length());
2494   if (has_preresolution()) st->print("/preresolution");
2495   if (operands() != nullptr)  st->print("/operands[%d]", operands()->length());
2496   print_address_on(st);
2497   if (pool_holder() != nullptr) {
2498     st->print(" for ");
2499     pool_holder()->print_value_on(st);
2500     bool extra = (pool_holder()->constants() != this);
2501     if (extra)  st->print(" (extra)");
2502   }
2503   if (cache() != nullptr) {
2504     st->print(" cache=" PTR_FORMAT, p2i(cache()));
2505   }
2506 }
2507 
2508 // Verification
2509 
2510 void ConstantPool::verify_on(outputStream* st) {
2511   guarantee(is_constantPool(), "object must be constant pool");
2512   for (int i = 0; i< length();  i++) {
2513     constantTag tag = tag_at(i);
2514     if (tag.is_klass() || tag.is_unresolved_klass()) {
2515       guarantee(klass_name_at(i)->refcount() != 0, "should have nonzero reference count");
2516     } else if (tag.is_symbol()) {
2517       Symbol* entry = symbol_at(i);
2518       guarantee(entry->refcount() != 0, "should have nonzero reference count");
2519     } else if (tag.is_string()) {
2520       Symbol* entry = unresolved_string_at(i);
2521       guarantee(entry->refcount() != 0, "should have nonzero reference count");
2522     }
2523   }
2524   if (pool_holder() != nullptr) {
2525     // Note: pool_holder() can be null in temporary constant pools
2526     // used during constant pool merging
2527     guarantee(pool_holder()->is_klass(),    "should be klass");
2528   }
2529 }