1 /*
   2  * Copyright (c) 1999, 2019, 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 "ci/ciCallSite.hpp"
  27 #include "ci/ciInstance.hpp"
  28 #include "ci/ciInstanceKlass.hpp"
  29 #include "ci/ciMemberName.hpp"
  30 #include "ci/ciMethod.hpp"
  31 #include "ci/ciMethodData.hpp"
  32 #include "ci/ciMethodHandle.hpp"
  33 #include "ci/ciMethodType.hpp"
  34 #include "ci/ciNullObject.hpp"
  35 #include "ci/ciObjArray.hpp"
  36 #include "ci/ciObjArrayKlass.hpp"
  37 #include "ci/ciObject.hpp"
  38 #include "ci/ciObjectFactory.hpp"
  39 #include "ci/ciSymbol.hpp"
  40 #include "ci/ciTypeArray.hpp"
  41 #include "ci/ciTypeArrayKlass.hpp"
  42 #include "ci/ciUtilities.inline.hpp"
  43 #include "classfile/javaClasses.inline.hpp"
  44 #include "classfile/systemDictionary.hpp"
  45 #include "gc/shared/collectedHeap.inline.hpp"
  46 #include "memory/allocation.inline.hpp"
  47 #include "memory/universe.hpp"
  48 #include "oops/oop.inline.hpp"
  49 #include "runtime/fieldType.hpp"
  50 #include "runtime/handles.inline.hpp"
  51 #include "utilities/macros.hpp"
  52 
  53 // ciObjectFactory
  54 //
  55 // This class handles requests for the creation of new instances
  56 // of ciObject and its subclasses.  It contains a caching mechanism
  57 // which ensures that for each oop, at most one ciObject is created.
  58 // This invariant allows more efficient implementation of ciObject.
  59 //
  60 // Implementation note: the oop->ciObject mapping is represented as
  61 // a table stored in an array.  Even though objects are moved
  62 // by the garbage collector, the compactor preserves their relative
  63 // order; address comparison of oops (in perm space) is safe so long
  64 // as we prohibit GC during our comparisons.  We currently use binary
  65 // search to find the oop in the table, and inserting a new oop
  66 // into the table may be costly.  If this cost ends up being
  67 // problematic the underlying data structure can be switched to some
  68 // sort of balanced binary tree.
  69 
  70 GrowableArray<ciMetadata*>* ciObjectFactory::_shared_ci_metadata = NULL;
  71 ciSymbol*                 ciObjectFactory::_shared_ci_symbols[vmSymbols::SID_LIMIT];
  72 int                       ciObjectFactory::_shared_ident_limit = 0;
  73 volatile bool             ciObjectFactory::_initialized = false;
  74 
  75 
  76 // ------------------------------------------------------------------
  77 // ciObjectFactory::ciObjectFactory
  78 ciObjectFactory::ciObjectFactory(Arena* arena,
  79                                  int expected_size) {
  80 
  81   for (int i = 0; i < NON_PERM_BUCKETS; i++) {
  82     _non_perm_bucket[i] = NULL;
  83   }
  84   _non_perm_count = 0;
  85 
  86   _next_ident = _shared_ident_limit;
  87   _arena = arena;
  88   _ci_metadata = new (arena) GrowableArray<ciMetadata*>(arena, expected_size, 0, NULL);
  89 
  90   // If the shared ci objects exist append them to this factory's objects
  91 
  92   if (_shared_ci_metadata != NULL) {
  93     _ci_metadata->appendAll(_shared_ci_metadata);
  94   }
  95 
  96   _unloaded_methods = new (arena) GrowableArray<ciMethod*>(arena, 4, 0, NULL);
  97   _unloaded_klasses = new (arena) GrowableArray<ciKlass*>(arena, 8, 0, NULL);
  98   _unloaded_instances = new (arena) GrowableArray<ciInstance*>(arena, 4, 0, NULL);
  99   _return_addresses =
 100     new (arena) GrowableArray<ciReturnAddress*>(arena, 8, 0, NULL);
 101 
 102   _symbols = new (arena) GrowableArray<ciSymbol*>(arena, 100, 0, NULL);
 103 }
 104 
 105 // ------------------------------------------------------------------
 106 // ciObjectFactory::ciObjectFactory
 107 void ciObjectFactory::initialize() {
 108   ASSERT_IN_VM;
 109   JavaThread* thread = JavaThread::current();
 110   HandleMark  handle_mark(thread);
 111 
 112   // This Arena is long lived and exists in the resource mark of the
 113   // compiler thread that initializes the initial ciObjectFactory which
 114   // creates the shared ciObjects that all later ciObjectFactories use.
 115   Arena* arena = new (mtCompiler) Arena(mtCompiler);
 116   ciEnv initial(arena);
 117   ciEnv* env = ciEnv::current();
 118   env->_factory->init_shared_objects();
 119 
 120   _initialized = true;
 121 
 122 }
 123 
 124 void ciObjectFactory::init_shared_objects() {
 125 
 126   _next_ident = 1;  // start numbering CI objects at 1
 127 
 128   {
 129     // Create the shared symbols, but not in _shared_ci_metadata.
 130     int i;
 131     for (i = vmSymbols::FIRST_SID; i < vmSymbols::SID_LIMIT; i++) {
 132       Symbol* vmsym = vmSymbols::symbol_at((vmSymbols::SID) i);
 133       assert(vmSymbols::find_sid(vmsym) == i, "1-1 mapping");
 134       ciSymbol* sym = new (_arena) ciSymbol(vmsym, (vmSymbols::SID) i);
 135       init_ident_of(sym);
 136       _shared_ci_symbols[i] = sym;
 137     }
 138 #ifdef ASSERT
 139     for (i = vmSymbols::FIRST_SID; i < vmSymbols::SID_LIMIT; i++) {
 140       Symbol* vmsym = vmSymbols::symbol_at((vmSymbols::SID) i);
 141       ciSymbol* sym = vm_symbol_at((vmSymbols::SID) i);
 142       assert(sym->get_symbol() == vmsym, "oop must match");
 143     }
 144     assert(ciSymbol::void_class_signature()->get_symbol() == vmSymbols::void_class_signature(), "spot check");
 145 #endif
 146   }
 147 
 148   _ci_metadata = new (_arena) GrowableArray<ciMetadata*>(_arena, 64, 0, NULL);
 149 
 150   for (int i = T_BOOLEAN; i <= T_CONFLICT; i++) {
 151     BasicType t = (BasicType)i;
 152     if (type2name(t) != NULL && t != T_OBJECT && t != T_ARRAY && t != T_NARROWOOP && t != T_NARROWKLASS) {
 153       ciType::_basic_types[t] = new (_arena) ciType(t);
 154       init_ident_of(ciType::_basic_types[t]);
 155     }
 156   }
 157 
 158   ciEnv::_null_object_instance = new (_arena) ciNullObject();
 159   init_ident_of(ciEnv::_null_object_instance);
 160 
 161 #define WK_KLASS_DEFN(name, ignore_s)                              \
 162   if (SystemDictionary::name##_is_loaded()) \
 163     ciEnv::_##name = get_metadata(SystemDictionary::name())->as_instance_klass();
 164 
 165   WK_KLASSES_DO(WK_KLASS_DEFN)
 166 #undef WK_KLASS_DEFN
 167 
 168   for (int len = -1; len != _ci_metadata->length(); ) {
 169     len = _ci_metadata->length();
 170     for (int i2 = 0; i2 < len; i2++) {
 171       ciMetadata* obj = _ci_metadata->at(i2);
 172       assert (obj->is_metadata(), "what else would it be?");
 173       if (obj->is_loaded() && obj->is_instance_klass()) {
 174         obj->as_instance_klass()->compute_nonstatic_fields();
 175       }
 176     }
 177   }
 178 
 179   ciEnv::_unloaded_cisymbol = ciObjectFactory::get_symbol(vmSymbols::dummy_symbol());
 180   // Create dummy InstanceKlass and ObjArrayKlass object and assign them idents
 181   ciEnv::_unloaded_ciinstance_klass = new (_arena) ciInstanceKlass(ciEnv::_unloaded_cisymbol, NULL, NULL);
 182   init_ident_of(ciEnv::_unloaded_ciinstance_klass);
 183   ciEnv::_unloaded_ciobjarrayklass = new (_arena) ciObjArrayKlass(ciEnv::_unloaded_cisymbol, ciEnv::_unloaded_ciinstance_klass, 1);
 184   init_ident_of(ciEnv::_unloaded_ciobjarrayklass);
 185   assert(ciEnv::_unloaded_ciobjarrayklass->is_obj_array_klass(), "just checking");
 186 
 187   get_metadata(Universe::boolArrayKlassObj());
 188   get_metadata(Universe::charArrayKlassObj());
 189   get_metadata(Universe::floatArrayKlassObj());
 190   get_metadata(Universe::doubleArrayKlassObj());
 191   get_metadata(Universe::byteArrayKlassObj());
 192   get_metadata(Universe::shortArrayKlassObj());
 193   get_metadata(Universe::intArrayKlassObj());
 194   get_metadata(Universe::longArrayKlassObj());
 195 
 196 
 197 
 198   assert(_non_perm_count == 0, "no shared non-perm objects");
 199 
 200   // The shared_ident_limit is the first ident number that will
 201   // be used for non-shared objects.  That is, numbers less than
 202   // this limit are permanently assigned to shared CI objects,
 203   // while the higher numbers are recycled afresh by each new ciEnv.
 204 
 205   _shared_ident_limit = _next_ident;
 206   _shared_ci_metadata = _ci_metadata;
 207 }
 208 
 209 
 210 ciSymbol* ciObjectFactory::get_symbol(Symbol* key) {
 211   vmSymbols::SID sid = vmSymbols::find_sid(key);
 212   if (sid != vmSymbols::NO_SID) {
 213     // do not pollute the main cache with it
 214     return vm_symbol_at(sid);
 215   }
 216 
 217   assert(vmSymbols::find_sid(key) == vmSymbols::NO_SID, "");
 218   ciSymbol* s = new (arena()) ciSymbol(key, vmSymbols::NO_SID);
 219   _symbols->push(s);
 220   return s;
 221 }
 222 
 223 // Decrement the refcount when done on symbols referenced by this compilation.
 224 void ciObjectFactory::remove_symbols() {
 225   for (int i = 0; i < _symbols->length(); i++) {
 226     ciSymbol* s = _symbols->at(i);
 227     s->get_symbol()->decrement_refcount();
 228   }
 229   // Since _symbols is resource allocated we're not allowed to delete it
 230   // but it'll go away just the same.
 231 }
 232 
 233 // ------------------------------------------------------------------
 234 // ciObjectFactory::get
 235 //
 236 // Get the ciObject corresponding to some oop.  If the ciObject has
 237 // already been created, it is returned.  Otherwise, a new ciObject
 238 // is created.
 239 ciObject* ciObjectFactory::get(oop key) {
 240   ASSERT_IN_VM;
 241 
 242   assert(Universe::heap()->is_in(key), "must be");
 243 
 244   NonPermObject* &bucket = find_non_perm(key);
 245   if (bucket != NULL) {
 246     return bucket->object();
 247   }
 248 
 249   // The ciObject does not yet exist.  Create it and insert it
 250   // into the cache.
 251   Handle keyHandle(Thread::current(), key);
 252   ciObject* new_object = create_new_object(keyHandle());
 253   assert(oopDesc::equals(keyHandle(), new_object->get_oop()), "must be properly recorded");
 254   init_ident_of(new_object);
 255   assert(Universe::heap()->is_in(new_object->get_oop()), "must be");
 256 
 257   // Not a perm-space object.
 258   insert_non_perm(bucket, keyHandle(), new_object);
 259   return new_object;
 260 }
 261 
 262 int ciObjectFactory::metadata_compare(Metadata* const& key, ciMetadata* const& elt) {
 263   Metadata* value = elt->constant_encoding();
 264   if (key < value)      return -1;
 265   else if (key > value) return 1;
 266   else                  return 0;
 267 }
 268 
 269 // ------------------------------------------------------------------
 270 // ciObjectFactory::cached_metadata
 271 //
 272 // Get the ciMetadata corresponding to some Metadata. If the ciMetadata has
 273 // already been created, it is returned. Otherwise, null is returned.
 274 ciMetadata* ciObjectFactory::cached_metadata(Metadata* key) {
 275   ASSERT_IN_VM;
 276 
 277   bool found = false;
 278   int index = _ci_metadata->find_sorted<Metadata*, ciObjectFactory::metadata_compare>(key, found);
 279 
 280   if (!found) {
 281     return NULL;
 282   }
 283   return _ci_metadata->at(index)->as_metadata();
 284 }
 285 
 286 
 287 // ------------------------------------------------------------------
 288 // ciObjectFactory::get_metadata
 289 //
 290 // Get the ciMetadata corresponding to some Metadata. If the ciMetadata has
 291 // already been created, it is returned. Otherwise, a new ciMetadata
 292 // is created.
 293 ciMetadata* ciObjectFactory::get_metadata(Metadata* key) {
 294   ASSERT_IN_VM;
 295 
 296 #ifdef ASSERT
 297   if (CIObjectFactoryVerify) {
 298     Metadata* last = NULL;
 299     for (int j = 0; j< _ci_metadata->length(); j++) {
 300       Metadata* o = _ci_metadata->at(j)->constant_encoding();
 301       assert(last < o, "out of order");
 302       last = o;
 303     }
 304   }
 305 #endif // ASSERT
 306   int len = _ci_metadata->length();
 307   bool found = false;
 308   int index = _ci_metadata->find_sorted<Metadata*, ciObjectFactory::metadata_compare>(key, found);
 309 #ifdef ASSERT
 310   if (CIObjectFactoryVerify) {
 311     for (int i=0; i<_ci_metadata->length(); i++) {
 312       if (_ci_metadata->at(i)->constant_encoding() == key) {
 313         assert(index == i, " bad lookup");
 314       }
 315     }
 316   }
 317 #endif
 318 
 319   if (!found) {
 320     // The ciMetadata does not yet exist. Create it and insert it
 321     // into the cache.
 322     ciMetadata* new_object = create_new_metadata(key);
 323     init_ident_of(new_object);
 324     assert(new_object->is_metadata(), "must be");
 325 
 326     if (len != _ci_metadata->length()) {
 327       // creating the new object has recursively entered new objects
 328       // into the table.  We need to recompute our index.
 329       index = _ci_metadata->find_sorted<Metadata*, ciObjectFactory::metadata_compare>(key, found);
 330     }
 331     assert(!found, "no double insert");
 332     _ci_metadata->insert_before(index, new_object);
 333     return new_object;
 334   }
 335   return _ci_metadata->at(index)->as_metadata();
 336 }
 337 
 338 // ------------------------------------------------------------------
 339 // ciObjectFactory::create_new_object
 340 //
 341 // Create a new ciObject from an oop.
 342 //
 343 // Implementation note: this functionality could be virtual behavior
 344 // of the oop itself.  For now, we explicitly marshal the object.
 345 ciObject* ciObjectFactory::create_new_object(oop o) {
 346   EXCEPTION_CONTEXT;
 347 
 348   if (o->is_instance()) {
 349     instanceHandle h_i(THREAD, (instanceOop)o);
 350     if (java_lang_invoke_CallSite::is_instance(o))
 351       return new (arena()) ciCallSite(h_i);
 352     else if (java_lang_invoke_MemberName::is_instance(o))
 353       return new (arena()) ciMemberName(h_i);
 354     else if (java_lang_invoke_MethodHandle::is_instance(o))
 355       return new (arena()) ciMethodHandle(h_i);
 356     else if (java_lang_invoke_MethodType::is_instance(o))
 357       return new (arena()) ciMethodType(h_i);
 358     else
 359       return new (arena()) ciInstance(h_i);
 360   } else if (o->is_objArray()) {
 361     objArrayHandle h_oa(THREAD, (objArrayOop)o);
 362     return new (arena()) ciObjArray(h_oa);
 363   } else if (o->is_typeArray()) {
 364     typeArrayHandle h_ta(THREAD, (typeArrayOop)o);
 365     return new (arena()) ciTypeArray(h_ta);
 366   }
 367 
 368   // The oop is of some type not supported by the compiler interface.
 369   ShouldNotReachHere();
 370   return NULL;
 371 }
 372 
 373 // ------------------------------------------------------------------
 374 // ciObjectFactory::create_new_metadata
 375 //
 376 // Create a new ciMetadata from a Metadata*.
 377 //
 378 // Implementation note: in order to keep Metadata live, an auxiliary ciObject
 379 // is used, which points to it's holder.
 380 ciMetadata* ciObjectFactory::create_new_metadata(Metadata* o) {
 381   EXCEPTION_CONTEXT;
 382 
 383   if (o->is_klass()) {
 384     Klass* k = (Klass*)o;
 385     if (k->is_instance_klass()) {
 386       return new (arena()) ciInstanceKlass(k);
 387     } else if (k->is_objArray_klass()) {
 388       return new (arena()) ciObjArrayKlass(k);
 389     } else if (k->is_typeArray_klass()) {
 390       return new (arena()) ciTypeArrayKlass(k);
 391     }
 392   } else if (o->is_method()) {
 393     methodHandle h_m(THREAD, (Method*)o);
 394     ciEnv *env = CURRENT_THREAD_ENV;
 395     ciInstanceKlass* holder = env->get_instance_klass(h_m()->method_holder());
 396     return new (arena()) ciMethod(h_m, holder);
 397   } else if (o->is_methodData()) {
 398     // Hold methodHandle alive - might not be necessary ???
 399     methodHandle h_m(THREAD, ((MethodData*)o)->method());
 400     return new (arena()) ciMethodData((MethodData*)o);
 401   }
 402 
 403   // The Metadata* is of some type not supported by the compiler interface.
 404   ShouldNotReachHere();
 405   return NULL;
 406 }
 407 
 408 //------------------------------------------------------------------
 409 // ciObjectFactory::get_unloaded_method
 410 //
 411 // Get the ciMethod representing an unloaded/unfound method.
 412 //
 413 // Implementation note: unloaded methods are currently stored in
 414 // an unordered array, requiring a linear-time lookup for each
 415 // unloaded method.  This may need to change.
 416 ciMethod* ciObjectFactory::get_unloaded_method(ciInstanceKlass* holder,
 417                                                ciSymbol*        name,
 418                                                ciSymbol*        signature,
 419                                                ciInstanceKlass* accessor) {
 420   ciSignature* that = NULL;
 421   for (int i = 0; i < _unloaded_methods->length(); i++) {
 422     ciMethod* entry = _unloaded_methods->at(i);
 423     if (entry->holder()->equals(holder) &&
 424         entry->name()->equals(name) &&
 425         entry->signature()->as_symbol()->equals(signature)) {
 426       // Short-circuit slow resolve.
 427       if (entry->signature()->accessing_klass() == accessor) {
 428         // We've found a match.
 429         return entry;
 430       } else {
 431         // Lazily create ciSignature
 432         if (that == NULL)  that = new (arena()) ciSignature(accessor, constantPoolHandle(), signature);
 433         if (entry->signature()->equals(that)) {
 434           // We've found a match.
 435           return entry;
 436         }
 437       }
 438     }
 439   }
 440 
 441   // This is a new unloaded method.  Create it and stick it in
 442   // the cache.
 443   ciMethod* new_method = new (arena()) ciMethod(holder, name, signature, accessor);
 444 
 445   init_ident_of(new_method);
 446   _unloaded_methods->append(new_method);
 447 
 448   return new_method;
 449 }
 450 
 451 //------------------------------------------------------------------
 452 // ciObjectFactory::get_unloaded_klass
 453 //
 454 // Get a ciKlass representing an unloaded klass.
 455 //
 456 // Implementation note: unloaded klasses are currently stored in
 457 // an unordered array, requiring a linear-time lookup for each
 458 // unloaded klass.  This may need to change.
 459 ciKlass* ciObjectFactory::get_unloaded_klass(ciKlass* accessing_klass,
 460                                              ciSymbol* name,
 461                                              bool create_if_not_found) {
 462   EXCEPTION_CONTEXT;
 463   oop loader = NULL;
 464   oop domain = NULL;
 465   if (accessing_klass != NULL) {
 466     loader = accessing_klass->loader();
 467     domain = accessing_klass->protection_domain();
 468   }
 469   for (int i=0; i<_unloaded_klasses->length(); i++) {
 470     ciKlass* entry = _unloaded_klasses->at(i);
 471     if (entry->name()->equals(name) &&
 472         oopDesc::equals(entry->loader(), loader) &&
 473         oopDesc::equals(entry->protection_domain(), domain)) {
 474       // We've found a match.
 475       return entry;
 476     }
 477   }
 478 
 479   if (!create_if_not_found)
 480     return NULL;
 481 
 482   // This is a new unloaded klass.  Create it and stick it in
 483   // the cache.
 484   ciKlass* new_klass = NULL;
 485 
 486   // Two cases: this is an unloaded ObjArrayKlass or an
 487   // unloaded InstanceKlass.  Deal with both.
 488   if (name->char_at(0) == '[') {
 489     // Decompose the name.'
 490     FieldArrayInfo fd;
 491     BasicType element_type = FieldType::get_array_info(name->get_symbol(),
 492                                                        fd, THREAD);
 493     if (HAS_PENDING_EXCEPTION) {
 494       CLEAR_PENDING_EXCEPTION;
 495       CURRENT_THREAD_ENV->record_out_of_memory_failure();
 496       return ciEnv::_unloaded_ciobjarrayklass;
 497     }
 498     int dimension = fd.dimension();
 499     assert(element_type != T_ARRAY, "unsuccessful decomposition");
 500     ciKlass* element_klass = NULL;
 501     if (element_type == T_OBJECT) {
 502       ciEnv *env = CURRENT_THREAD_ENV;
 503       ciSymbol* ci_name = env->get_symbol(fd.object_key());
 504       element_klass =
 505         env->get_klass_by_name(accessing_klass, ci_name, false)->as_instance_klass();
 506     } else {
 507       assert(dimension > 1, "one dimensional type arrays are always loaded.");
 508 
 509       // The type array itself takes care of one of the dimensions.
 510       dimension--;
 511 
 512       // The element klass is a TypeArrayKlass.
 513       element_klass = ciTypeArrayKlass::make(element_type);
 514     }
 515     new_klass = new (arena()) ciObjArrayKlass(name, element_klass, dimension);
 516   } else {
 517     jobject loader_handle = NULL;
 518     jobject domain_handle = NULL;
 519     if (accessing_klass != NULL) {
 520       loader_handle = accessing_klass->loader_handle();
 521       domain_handle = accessing_klass->protection_domain_handle();
 522     }
 523     new_klass = new (arena()) ciInstanceKlass(name, loader_handle, domain_handle);
 524   }
 525   init_ident_of(new_klass);
 526   _unloaded_klasses->append(new_klass);
 527 
 528   return new_klass;
 529 }
 530 
 531 
 532 //------------------------------------------------------------------
 533 // ciObjectFactory::get_unloaded_instance
 534 //
 535 // Get a ciInstance representing an as-yet undetermined instance of a given class.
 536 //
 537 ciInstance* ciObjectFactory::get_unloaded_instance(ciInstanceKlass* instance_klass) {
 538   for (int i=0; i<_unloaded_instances->length(); i++) {
 539     ciInstance* entry = _unloaded_instances->at(i);
 540     if (entry->klass()->equals(instance_klass)) {
 541       // We've found a match.
 542       return entry;
 543     }
 544   }
 545 
 546   // This is a new unloaded instance.  Create it and stick it in
 547   // the cache.
 548   ciInstance* new_instance = new (arena()) ciInstance(instance_klass);
 549 
 550   init_ident_of(new_instance);
 551   _unloaded_instances->append(new_instance);
 552 
 553   // make sure it looks the way we want:
 554   assert(!new_instance->is_loaded(), "");
 555   assert(new_instance->klass() == instance_klass, "");
 556 
 557   return new_instance;
 558 }
 559 
 560 
 561 //------------------------------------------------------------------
 562 // ciObjectFactory::get_unloaded_klass_mirror
 563 //
 564 // Get a ciInstance representing an unresolved klass mirror.
 565 //
 566 // Currently, this ignores the parameters and returns a unique unloaded instance.
 567 ciInstance* ciObjectFactory::get_unloaded_klass_mirror(ciKlass*  type) {
 568   assert(ciEnv::_Class_klass != NULL, "");
 569   return get_unloaded_instance(ciEnv::_Class_klass->as_instance_klass());
 570 }
 571 
 572 //------------------------------------------------------------------
 573 // ciObjectFactory::get_unloaded_method_handle_constant
 574 //
 575 // Get a ciInstance representing an unresolved method handle constant.
 576 //
 577 // Currently, this ignores the parameters and returns a unique unloaded instance.
 578 ciInstance* ciObjectFactory::get_unloaded_method_handle_constant(ciKlass*  holder,
 579                                                                  ciSymbol* name,
 580                                                                  ciSymbol* signature,
 581                                                                  int       ref_kind) {
 582   if (ciEnv::_MethodHandle_klass == NULL)  return NULL;
 583   return get_unloaded_instance(ciEnv::_MethodHandle_klass->as_instance_klass());
 584 }
 585 
 586 //------------------------------------------------------------------
 587 // ciObjectFactory::get_unloaded_method_type_constant
 588 //
 589 // Get a ciInstance representing an unresolved method type constant.
 590 //
 591 // Currently, this ignores the parameters and returns a unique unloaded instance.
 592 ciInstance* ciObjectFactory::get_unloaded_method_type_constant(ciSymbol* signature) {
 593   if (ciEnv::_MethodType_klass == NULL)  return NULL;
 594   return get_unloaded_instance(ciEnv::_MethodType_klass->as_instance_klass());
 595 }
 596 
 597 ciInstance* ciObjectFactory::get_unloaded_object_constant() {
 598   if (ciEnv::_Object_klass == NULL)  return NULL;
 599   return get_unloaded_instance(ciEnv::_Object_klass->as_instance_klass());
 600 }
 601 
 602 //------------------------------------------------------------------
 603 // ciObjectFactory::get_empty_methodData
 604 //
 605 // Get the ciMethodData representing the methodData for a method with
 606 // none.
 607 ciMethodData* ciObjectFactory::get_empty_methodData() {
 608   ciMethodData* new_methodData = new (arena()) ciMethodData();
 609   init_ident_of(new_methodData);
 610   return new_methodData;
 611 }
 612 
 613 //------------------------------------------------------------------
 614 // ciObjectFactory::get_return_address
 615 //
 616 // Get a ciReturnAddress for a specified bci.
 617 ciReturnAddress* ciObjectFactory::get_return_address(int bci) {
 618   for (int i=0; i<_return_addresses->length(); i++) {
 619     ciReturnAddress* entry = _return_addresses->at(i);
 620     if (entry->bci() == bci) {
 621       // We've found a match.
 622       return entry;
 623     }
 624   }
 625 
 626   ciReturnAddress* new_ret_addr = new (arena()) ciReturnAddress(bci);
 627   init_ident_of(new_ret_addr);
 628   _return_addresses->append(new_ret_addr);
 629   return new_ret_addr;
 630 }
 631 
 632 // ------------------------------------------------------------------
 633 // ciObjectFactory::init_ident_of
 634 void ciObjectFactory::init_ident_of(ciBaseObject* obj) {
 635   obj->set_ident(_next_ident++);
 636 }
 637 
 638 static ciObjectFactory::NonPermObject* emptyBucket = NULL;
 639 
 640 // ------------------------------------------------------------------
 641 // ciObjectFactory::find_non_perm
 642 //
 643 // Use a small hash table, hashed on the klass of the key.
 644 // If there is no entry in the cache corresponding to this oop, return
 645 // the null tail of the bucket into which the oop should be inserted.
 646 ciObjectFactory::NonPermObject* &ciObjectFactory::find_non_perm(oop key) {
 647   assert(Universe::heap()->is_in(key), "must be");
 648   ciMetadata* klass = get_metadata(key->klass());
 649   NonPermObject* *bp = &_non_perm_bucket[(unsigned) klass->hash() % NON_PERM_BUCKETS];
 650   for (NonPermObject* p; (p = (*bp)) != NULL; bp = &p->next()) {
 651     if (is_equal(p, key))  break;
 652   }
 653   return (*bp);
 654 }
 655 
 656 
 657 
 658 // ------------------------------------------------------------------
 659 // Code for for NonPermObject
 660 //
 661 inline ciObjectFactory::NonPermObject::NonPermObject(ciObjectFactory::NonPermObject* &bucket, oop key, ciObject* object) {
 662   assert(ciObjectFactory::is_initialized(), "");
 663   _object = object;
 664   _next = bucket;
 665   bucket = this;
 666 }
 667 
 668 
 669 
 670 // ------------------------------------------------------------------
 671 // ciObjectFactory::insert_non_perm
 672 //
 673 // Insert a ciObject into the non-perm table.
 674 void ciObjectFactory::insert_non_perm(ciObjectFactory::NonPermObject* &where, oop key, ciObject* obj) {
 675   assert(Universe::heap()->is_in_or_null(key), "must be");
 676   assert(&where != &emptyBucket, "must not try to fill empty bucket");
 677   NonPermObject* p = new (arena()) NonPermObject(where, key, obj);
 678   assert(where == p && is_equal(p, key) && p->object() == obj, "entry must match");
 679   assert(find_non_perm(key) == p, "must find the same spot");
 680   ++_non_perm_count;
 681 }
 682 
 683 // ------------------------------------------------------------------
 684 // ciObjectFactory::vm_symbol_at
 685 // Get the ciSymbol corresponding to some index in vmSymbols.
 686 ciSymbol* ciObjectFactory::vm_symbol_at(int index) {
 687   assert(index >= vmSymbols::FIRST_SID && index < vmSymbols::SID_LIMIT, "oob");
 688   return _shared_ci_symbols[index];
 689 }
 690 
 691 // ------------------------------------------------------------------
 692 // ciObjectFactory::metadata_do
 693 void ciObjectFactory::metadata_do(MetadataClosure* f) {
 694   if (_ci_metadata == NULL) return;
 695   for (int j = 0; j< _ci_metadata->length(); j++) {
 696     Metadata* o = _ci_metadata->at(j)->constant_encoding();
 697     f->do_metadata(o);
 698   }
 699 }
 700 
 701 // ------------------------------------------------------------------
 702 // ciObjectFactory::print_contents_impl
 703 void ciObjectFactory::print_contents_impl() {
 704   int len = _ci_metadata->length();
 705   tty->print_cr("ciObjectFactory (%d) meta data contents:", len);
 706   for (int i=0; i<len; i++) {
 707     _ci_metadata->at(i)->print();
 708     tty->cr();
 709   }
 710 }
 711 
 712 // ------------------------------------------------------------------
 713 // ciObjectFactory::print_contents
 714 void ciObjectFactory::print_contents() {
 715   print();
 716   tty->cr();
 717   GUARDED_VM_ENTRY(print_contents_impl();)
 718 }
 719 
 720 // ------------------------------------------------------------------
 721 // ciObjectFactory::print
 722 //
 723 // Print debugging information about the object factory
 724 void ciObjectFactory::print() {
 725   tty->print("<ciObjectFactory oops=%d metadata=%d unloaded_methods=%d unloaded_instances=%d unloaded_klasses=%d>",
 726              _non_perm_count, _ci_metadata->length(), _unloaded_methods->length(),
 727              _unloaded_instances->length(),
 728              _unloaded_klasses->length());
 729 }