1 /*
  2  * Copyright (c) 1999, 2021, 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/ciNativeEntryPoint.hpp"
 31 #include "ci/ciMethod.hpp"
 32 #include "ci/ciMethodData.hpp"
 33 #include "ci/ciMethodHandle.hpp"
 34 #include "ci/ciMethodType.hpp"
 35 #include "ci/ciNullObject.hpp"
 36 #include "ci/ciObjArray.hpp"
 37 #include "ci/ciObjArrayKlass.hpp"
 38 #include "ci/ciObject.hpp"
 39 #include "ci/ciObjectFactory.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 = NULL;
 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, NULL),
 85                                    _unloaded_methods(arena, 4, 0, NULL),
 86                                    _unloaded_klasses(arena, 8, 0, NULL),
 87                                    _unloaded_instances(arena, 4, 0, NULL),
 88                                    _return_addresses(arena, 8, 0, NULL),
 89                                    _symbols(arena, 100, 0, NULL),
 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] = NULL;
 94   }
 95 
 96   // If the shared ci objects exist append them to this factory's objects
 97   if (_shared_ci_metadata != NULL) {
 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) != NULL && !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       }
171     }
172   }
173 
174   ciEnv::_unloaded_cisymbol = ciObjectFactory::get_symbol(vmSymbols::dummy_symbol());
175   // Create dummy InstanceKlass and ObjArrayKlass object and assign them idents
176   ciEnv::_unloaded_ciinstance_klass = new (_arena) ciInstanceKlass(ciEnv::_unloaded_cisymbol, NULL, NULL);
177   init_ident_of(ciEnv::_unloaded_ciinstance_klass);
178   ciEnv::_unloaded_ciobjarrayklass = new (_arena) ciObjArrayKlass(ciEnv::_unloaded_cisymbol, ciEnv::_unloaded_ciinstance_klass, 1);
179   init_ident_of(ciEnv::_unloaded_ciobjarrayklass);
180   assert(ciEnv::_unloaded_ciobjarrayklass->is_obj_array_klass(), "just checking");
181 
182   get_metadata(Universe::boolArrayKlassObj());
183   get_metadata(Universe::charArrayKlassObj());
184   get_metadata(Universe::floatArrayKlassObj());
185   get_metadata(Universe::doubleArrayKlassObj());
186   get_metadata(Universe::byteArrayKlassObj());
187   get_metadata(Universe::shortArrayKlassObj());
188   get_metadata(Universe::intArrayKlassObj());
189   get_metadata(Universe::longArrayKlassObj());
190 
191   assert(_non_perm_count == 0, "no shared non-perm objects");
192 
193   // The shared_ident_limit is the first ident number that will
194   // be used for non-shared objects.  That is, numbers less than
195   // this limit are permanently assigned to shared CI objects,
196   // while the higher numbers are recycled afresh by each new ciEnv.
197 
198   _shared_ident_limit = _next_ident;
199   _shared_ci_metadata = &_ci_metadata;
200 }
201 
202 
203 ciSymbol* ciObjectFactory::get_symbol(Symbol* key) {
204   vmSymbolID sid = vmSymbols::find_sid(key);
205   if (sid != vmSymbolID::NO_SID) {
206     // do not pollute the main cache with it
207     return vm_symbol_at(sid);
208   }
209 
210   assert(vmSymbols::find_sid(key) == vmSymbolID::NO_SID, "");
211   ciSymbol* s = new (arena()) ciSymbol(key, vmSymbolID::NO_SID);
212   _symbols.push(s);
213   return s;
214 }
215 
216 // Decrement the refcount when done on symbols referenced by this compilation.
217 void ciObjectFactory::remove_symbols() {
218   for (int i = 0; i < _symbols.length(); i++) {
219     ciSymbol* s = _symbols.at(i);
220     s->get_symbol()->decrement_refcount();
221   }
222   // Since _symbols is resource allocated we're not allowed to delete it
223   // but it'll go away just the same.
224 }
225 
226 // ------------------------------------------------------------------
227 // ciObjectFactory::get
228 //
229 // Get the ciObject corresponding to some oop.  If the ciObject has
230 // already been created, it is returned.  Otherwise, a new ciObject
231 // is created.
232 ciObject* ciObjectFactory::get(oop key) {
233   ASSERT_IN_VM;
234 
235   assert(Universe::heap()->is_in(key), "must be");
236 
237   NonPermObject* &bucket = find_non_perm(key);
238   if (bucket != NULL) {
239     return bucket->object();
240   }
241 
242   // The ciObject does not yet exist.  Create it and insert it
243   // into the cache.
244   Handle keyHandle(Thread::current(), key);
245   ciObject* new_object = create_new_object(keyHandle());
246   assert(keyHandle() == new_object->get_oop(), "must be properly recorded");
247   init_ident_of(new_object);
248   assert(Universe::heap()->is_in(new_object->get_oop()), "must be");
249 
250   // Not a perm-space object.
251   insert_non_perm(bucket, keyHandle(), new_object);
252   return new_object;
253 }
254 
255 int ciObjectFactory::metadata_compare(Metadata* const& key, ciMetadata* const& elt) {
256   Metadata* value = elt->constant_encoding();
257   if (key < value)      return -1;
258   else if (key > value) return 1;
259   else                  return 0;
260 }
261 
262 // ------------------------------------------------------------------
263 // ciObjectFactory::cached_metadata
264 //
265 // Get the ciMetadata corresponding to some Metadata. If the ciMetadata has
266 // already been created, it is returned. Otherwise, null is returned.
267 ciMetadata* ciObjectFactory::cached_metadata(Metadata* key) {
268   ASSERT_IN_VM;
269 
270   bool found = false;
271   int index = _ci_metadata.find_sorted<Metadata*, ciObjectFactory::metadata_compare>(key, found);
272 
273   if (!found) {
274     return NULL;
275   }
276   return _ci_metadata.at(index)->as_metadata();
277 }
278 
279 
280 // ------------------------------------------------------------------
281 // ciObjectFactory::get_metadata
282 //
283 // Get the ciMetadata corresponding to some Metadata. If the ciMetadata has
284 // already been created, it is returned. Otherwise, a new ciMetadata
285 // is created.
286 ciMetadata* ciObjectFactory::get_metadata(Metadata* key) {
287   ASSERT_IN_VM;
288 
289 #ifdef ASSERT
290   if (CIObjectFactoryVerify) {
291     Metadata* last = NULL;
292     for (int j = 0; j < _ci_metadata.length(); j++) {
293       Metadata* o = _ci_metadata.at(j)->constant_encoding();
294       assert(last < o, "out of order");
295       last = o;
296     }
297   }
298 #endif // ASSERT
299   int len = _ci_metadata.length();
300   bool found = false;
301   int index = _ci_metadata.find_sorted<Metadata*, ciObjectFactory::metadata_compare>(key, found);
302 #ifdef ASSERT
303   if (CIObjectFactoryVerify) {
304     for (int i = 0; i < _ci_metadata.length(); i++) {
305       if (_ci_metadata.at(i)->constant_encoding() == key) {
306         assert(index == i, " bad lookup");
307       }
308     }
309   }
310 #endif
311 
312   if (!found) {
313     // The ciMetadata does not yet exist. Create it and insert it
314     // into the cache.
315     ciMetadata* new_object = create_new_metadata(key);
316     init_ident_of(new_object);
317     assert(new_object->is_metadata(), "must be");
318 
319     if (len != _ci_metadata.length()) {
320       // creating the new object has recursively entered new objects
321       // into the table.  We need to recompute our index.
322       index = _ci_metadata.find_sorted<Metadata*, ciObjectFactory::metadata_compare>(key, found);
323     }
324     assert(!found, "no double insert");
325     _ci_metadata.insert_before(index, new_object);
326     return new_object;
327   }
328   return _ci_metadata.at(index)->as_metadata();
329 }
330 
331 // ------------------------------------------------------------------
332 // ciObjectFactory::create_new_object
333 //
334 // Create a new ciObject from an oop.
335 //
336 // Implementation note: this functionality could be virtual behavior
337 // of the oop itself.  For now, we explicitly marshal the object.
338 ciObject* ciObjectFactory::create_new_object(oop o) {
339   EXCEPTION_CONTEXT;
340 
341   if (o->is_instance()) {
342     instanceHandle h_i(THREAD, (instanceOop)o);
343     if (java_lang_invoke_CallSite::is_instance(o))
344       return new (arena()) ciCallSite(h_i);
345     else if (java_lang_invoke_MemberName::is_instance(o))
346       return new (arena()) ciMemberName(h_i);
347     else if (jdk_internal_invoke_NativeEntryPoint::is_instance(o))
348       return new (arena()) ciNativeEntryPoint(h_i);
349     else if (java_lang_invoke_MethodHandle::is_instance(o))
350       return new (arena()) ciMethodHandle(h_i);
351     else if (java_lang_invoke_MethodType::is_instance(o))
352       return new (arena()) ciMethodType(h_i);
353     else
354       return new (arena()) ciInstance(h_i);
355   } else if (o->is_objArray()) {
356     objArrayHandle h_oa(THREAD, (objArrayOop)o);
357     return new (arena()) ciObjArray(h_oa);
358   } else if (o->is_typeArray()) {
359     typeArrayHandle h_ta(THREAD, (typeArrayOop)o);
360     return new (arena()) ciTypeArray(h_ta);
361   }
362 
363   // The oop is of some type not supported by the compiler interface.
364   ShouldNotReachHere();
365   return NULL;
366 }
367 
368 // ------------------------------------------------------------------
369 // ciObjectFactory::create_new_metadata
370 //
371 // Create a new ciMetadata from a Metadata*.
372 //
373 // Implementation note: in order to keep Metadata live, an auxiliary ciObject
374 // is used, which points to it's holder.
375 ciMetadata* ciObjectFactory::create_new_metadata(Metadata* o) {
376   EXCEPTION_CONTEXT;
377 
378   if (o->is_klass()) {
379     Klass* k = (Klass*)o;
380     if (k->is_instance_klass()) {
381       return new (arena()) ciInstanceKlass(k);
382     } else if (k->is_objArray_klass()) {
383       return new (arena()) ciObjArrayKlass(k);
384     } else if (k->is_typeArray_klass()) {
385       return new (arena()) ciTypeArrayKlass(k);
386     }
387   } else if (o->is_method()) {
388     methodHandle h_m(THREAD, (Method*)o);
389     ciEnv *env = CURRENT_THREAD_ENV;
390     ciInstanceKlass* holder = env->get_instance_klass(h_m()->method_holder());
391     return new (arena()) ciMethod(h_m, holder);
392   } else if (o->is_methodData()) {
393     // Hold methodHandle alive - might not be necessary ???
394     methodHandle h_m(THREAD, ((MethodData*)o)->method());
395     return new (arena()) ciMethodData((MethodData*)o);
396   }
397 
398   // The Metadata* is of some type not supported by the compiler interface.
399   ShouldNotReachHere();
400   return NULL;
401 }
402 
403 //------------------------------------------------------------------
404 // ciObjectFactory::get_unloaded_method
405 //
406 // Get the ciMethod representing an unloaded/unfound method.
407 //
408 // Implementation note: unloaded methods are currently stored in
409 // an unordered array, requiring a linear-time lookup for each
410 // unloaded method.  This may need to change.
411 ciMethod* ciObjectFactory::get_unloaded_method(ciInstanceKlass* holder,
412                                                ciSymbol*        name,
413                                                ciSymbol*        signature,
414                                                ciInstanceKlass* accessor) {
415   assert(accessor != NULL, "need origin of access");
416   ciSignature* that = NULL;
417   for (int i = 0; i < _unloaded_methods.length(); i++) {
418     ciMethod* entry = _unloaded_methods.at(i);
419     if (entry->holder()->equals(holder) &&
420         entry->name()->equals(name) &&
421         entry->signature()->as_symbol()->equals(signature)) {
422       // Short-circuit slow resolve.
423       if (entry->signature()->accessing_klass() == accessor) {
424         // We've found a match.
425         return entry;
426       } else {
427         // Lazily create ciSignature
428         if (that == NULL)  that = new (arena()) ciSignature(accessor, constantPoolHandle(), signature);
429         if (entry->signature()->equals(that)) {
430           // We've found a match.
431           return entry;
432         }
433       }
434     }
435   }
436 
437   // This is a new unloaded method.  Create it and stick it in
438   // the cache.
439   ciMethod* new_method = new (arena()) ciMethod(holder, name, signature, accessor);
440 
441   init_ident_of(new_method);
442   _unloaded_methods.append(new_method);
443 
444   return new_method;
445 }
446 
447 //------------------------------------------------------------------
448 // ciObjectFactory::get_unloaded_klass
449 //
450 // Get a ciKlass representing an unloaded klass.
451 //
452 // Implementation note: unloaded klasses are currently stored in
453 // an unordered array, requiring a linear-time lookup for each
454 // unloaded klass.  This may need to change.
455 ciKlass* ciObjectFactory::get_unloaded_klass(ciKlass* accessing_klass,
456                                              ciSymbol* name,
457                                              bool create_if_not_found) {
458   EXCEPTION_CONTEXT;
459   oop loader = NULL;
460   oop domain = NULL;
461   if (accessing_klass != NULL) {
462     loader = accessing_klass->loader();
463     domain = accessing_klass->protection_domain();
464   }
465   for (int i = 0; i < _unloaded_klasses.length(); i++) {
466     ciKlass* entry = _unloaded_klasses.at(i);
467     if (entry->name()->equals(name) &&
468         entry->loader() == loader &&
469         entry->protection_domain() == domain) {
470       // We've found a match.
471       return entry;
472     }
473   }
474 
475   if (!create_if_not_found)
476     return NULL;
477 
478   // This is a new unloaded klass.  Create it and stick it in
479   // the cache.
480   ciKlass* new_klass = NULL;
481 
482   // Two cases: this is an unloaded ObjArrayKlass or an
483   // unloaded InstanceKlass.  Deal with both.
484   if (name->char_at(0) == JVM_SIGNATURE_ARRAY) {
485     // Decompose the name.'
486     SignatureStream ss(name->get_symbol(), false);
487     int dimension = ss.skip_array_prefix();  // skip all '['s
488     BasicType element_type = ss.type();
489     assert(element_type != T_ARRAY, "unsuccessful decomposition");
490     ciKlass* element_klass = NULL;
491     if (element_type == T_OBJECT) {
492       ciEnv *env = CURRENT_THREAD_ENV;
493       ciSymbol* ci_name = env->get_symbol(ss.as_symbol());
494       element_klass =
495         env->get_klass_by_name(accessing_klass, ci_name, false)->as_instance_klass();
496     } else {
497       assert(dimension > 1, "one dimensional type arrays are always loaded.");
498 
499       // The type array itself takes care of one of the dimensions.
500       dimension--;
501 
502       // The element klass is a TypeArrayKlass.
503       element_klass = ciTypeArrayKlass::make(element_type);
504     }
505     new_klass = new (arena()) ciObjArrayKlass(name, element_klass, dimension);
506   } else {
507     jobject loader_handle = NULL;
508     jobject domain_handle = NULL;
509     if (accessing_klass != NULL) {
510       loader_handle = accessing_klass->loader_handle();
511       domain_handle = accessing_klass->protection_domain_handle();
512     }
513     new_klass = new (arena()) ciInstanceKlass(name, loader_handle, domain_handle);
514   }
515   init_ident_of(new_klass);
516   _unloaded_klasses.append(new_klass);
517 
518   return new_klass;
519 }
520 
521 
522 //------------------------------------------------------------------
523 // ciObjectFactory::get_unloaded_instance
524 //
525 // Get a ciInstance representing an as-yet undetermined instance of a given class.
526 //
527 ciInstance* ciObjectFactory::get_unloaded_instance(ciInstanceKlass* instance_klass) {
528   for (int i = 0; i < _unloaded_instances.length(); i++) {
529     ciInstance* entry = _unloaded_instances.at(i);
530     if (entry->klass()->equals(instance_klass)) {
531       // We've found a match.
532       return entry;
533     }
534   }
535 
536   // This is a new unloaded instance.  Create it and stick it in
537   // the cache.
538   ciInstance* new_instance = new (arena()) ciInstance(instance_klass);
539 
540   init_ident_of(new_instance);
541   _unloaded_instances.append(new_instance);
542 
543   // make sure it looks the way we want:
544   assert(!new_instance->is_loaded(), "");
545   assert(new_instance->klass() == instance_klass, "");
546 
547   return new_instance;
548 }
549 
550 
551 //------------------------------------------------------------------
552 // ciObjectFactory::get_unloaded_klass_mirror
553 //
554 // Get a ciInstance representing an unresolved klass mirror.
555 //
556 // Currently, this ignores the parameters and returns a unique unloaded instance.
557 ciInstance* ciObjectFactory::get_unloaded_klass_mirror(ciKlass*  type) {
558   assert(ciEnv::_Class_klass != NULL, "");
559   return get_unloaded_instance(ciEnv::_Class_klass->as_instance_klass());
560 }
561 
562 //------------------------------------------------------------------
563 // ciObjectFactory::get_unloaded_method_handle_constant
564 //
565 // Get a ciInstance representing an unresolved method handle constant.
566 //
567 // Currently, this ignores the parameters and returns a unique unloaded instance.
568 ciInstance* ciObjectFactory::get_unloaded_method_handle_constant(ciKlass*  holder,
569                                                                  ciSymbol* name,
570                                                                  ciSymbol* signature,
571                                                                  int       ref_kind) {
572   if (ciEnv::_MethodHandle_klass == NULL)  return NULL;
573   return get_unloaded_instance(ciEnv::_MethodHandle_klass->as_instance_klass());
574 }
575 
576 //------------------------------------------------------------------
577 // ciObjectFactory::get_unloaded_method_type_constant
578 //
579 // Get a ciInstance representing an unresolved method type constant.
580 //
581 // Currently, this ignores the parameters and returns a unique unloaded instance.
582 ciInstance* ciObjectFactory::get_unloaded_method_type_constant(ciSymbol* signature) {
583   if (ciEnv::_MethodType_klass == NULL)  return NULL;
584   return get_unloaded_instance(ciEnv::_MethodType_klass->as_instance_klass());
585 }
586 
587 ciInstance* ciObjectFactory::get_unloaded_object_constant() {
588   if (ciEnv::_Object_klass == NULL)  return NULL;
589   return get_unloaded_instance(ciEnv::_Object_klass->as_instance_klass());
590 }
591 
592 //------------------------------------------------------------------
593 // ciObjectFactory::get_empty_methodData
594 //
595 // Get the ciMethodData representing the methodData for a method with
596 // none.
597 ciMethodData* ciObjectFactory::get_empty_methodData() {
598   ciMethodData* new_methodData = new (arena()) ciMethodData();
599   init_ident_of(new_methodData);
600   return new_methodData;
601 }
602 
603 //------------------------------------------------------------------
604 // ciObjectFactory::get_return_address
605 //
606 // Get a ciReturnAddress for a specified bci.
607 ciReturnAddress* ciObjectFactory::get_return_address(int bci) {
608   for (int i = 0; i < _return_addresses.length(); i++) {
609     ciReturnAddress* entry = _return_addresses.at(i);
610     if (entry->bci() == bci) {
611       // We've found a match.
612       return entry;
613     }
614   }
615 
616   ciReturnAddress* new_ret_addr = new (arena()) ciReturnAddress(bci);
617   init_ident_of(new_ret_addr);
618   _return_addresses.append(new_ret_addr);
619   return new_ret_addr;
620 }
621 
622 // ------------------------------------------------------------------
623 // ciObjectFactory::init_ident_of
624 void ciObjectFactory::init_ident_of(ciBaseObject* obj) {
625   obj->set_ident(_next_ident++);
626 }
627 
628 static ciObjectFactory::NonPermObject* emptyBucket = NULL;
629 
630 // ------------------------------------------------------------------
631 // ciObjectFactory::find_non_perm
632 //
633 // Use a small hash table, hashed on the klass of the key.
634 // If there is no entry in the cache corresponding to this oop, return
635 // the null tail of the bucket into which the oop should be inserted.
636 ciObjectFactory::NonPermObject* &ciObjectFactory::find_non_perm(oop key) {
637   assert(Universe::heap()->is_in(key), "must be");
638   ciMetadata* klass = get_metadata(key->klass());
639   NonPermObject* *bp = &_non_perm_bucket[(unsigned) klass->hash() % NON_PERM_BUCKETS];
640   for (NonPermObject* p; (p = (*bp)) != NULL; bp = &p->next()) {
641     if (is_equal(p, key))  break;
642   }
643   return (*bp);
644 }
645 
646 
647 
648 // ------------------------------------------------------------------
649 // Code for for NonPermObject
650 //
651 inline ciObjectFactory::NonPermObject::NonPermObject(ciObjectFactory::NonPermObject* &bucket, oop key, ciObject* object) {
652   assert(ciObjectFactory::is_initialized(), "");
653   _object = object;
654   _next = bucket;
655   bucket = this;
656 }
657 
658 
659 
660 // ------------------------------------------------------------------
661 // ciObjectFactory::insert_non_perm
662 //
663 // Insert a ciObject into the non-perm table.
664 void ciObjectFactory::insert_non_perm(ciObjectFactory::NonPermObject* &where, oop key, ciObject* obj) {
665   assert(Universe::heap()->is_in_or_null(key), "must be");
666   assert(&where != &emptyBucket, "must not try to fill empty bucket");
667   NonPermObject* p = new (arena()) NonPermObject(where, key, obj);
668   assert(where == p && is_equal(p, key) && p->object() == obj, "entry must match");
669   assert(find_non_perm(key) == p, "must find the same spot");
670   ++_non_perm_count;
671 }
672 
673 // ------------------------------------------------------------------
674 // ciObjectFactory::vm_symbol_at
675 // Get the ciSymbol corresponding to some index in vmSymbols.
676 ciSymbol* ciObjectFactory::vm_symbol_at(vmSymbolID sid) {
677   int index = vmSymbols::as_int(sid);
678   return _shared_ci_symbols[index];
679 }
680 
681 // ------------------------------------------------------------------
682 // ciObjectFactory::metadata_do
683 void ciObjectFactory::metadata_do(MetadataClosure* f) {
684   for (int j = 0; j < _ci_metadata.length(); j++) {
685     Metadata* o = _ci_metadata.at(j)->constant_encoding();
686     f->do_metadata(o);
687   }
688 }
689 
690 // ------------------------------------------------------------------
691 // ciObjectFactory::print_contents_impl
692 void ciObjectFactory::print_contents_impl() {
693   int len = _ci_metadata.length();
694   tty->print_cr("ciObjectFactory (%d) meta data contents:", len);
695   for (int i = 0; i < len; i++) {
696     _ci_metadata.at(i)->print();
697     tty->cr();
698   }
699 }
700 
701 // ------------------------------------------------------------------
702 // ciObjectFactory::print_contents
703 void ciObjectFactory::print_contents() {
704   print();
705   tty->cr();
706   GUARDED_VM_ENTRY(print_contents_impl();)
707 }
708 
709 // ------------------------------------------------------------------
710 // ciObjectFactory::print
711 //
712 // Print debugging information about the object factory
713 void ciObjectFactory::print() {
714   tty->print("<ciObjectFactory oops=%d metadata=%d unloaded_methods=%d unloaded_instances=%d unloaded_klasses=%d>",
715              _non_perm_count, _ci_metadata.length(), _unloaded_methods.length(),
716              _unloaded_instances.length(),
717              _unloaded_klasses.length());
718 }