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