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/ciFlatArray.hpp"
 28 #include "ci/ciFlatArrayKlass.hpp"
 29 #include "ci/ciInstance.hpp"
 30 #include "ci/ciInstanceKlass.hpp"
 31 #include "ci/ciMemberName.hpp"
 32 #include "ci/ciNativeEntryPoint.hpp"
 33 #include "ci/ciMethod.hpp"
 34 #include "ci/ciMethodData.hpp"
 35 #include "ci/ciMethodHandle.hpp"
 36 #include "ci/ciMethodType.hpp"
 37 #include "ci/ciNullObject.hpp"
 38 #include "ci/ciObjArray.hpp"
 39 #include "ci/ciObjArrayKlass.hpp"
 40 #include "ci/ciObject.hpp"
 41 #include "ci/ciObjectFactory.hpp"
 42 #include "ci/ciSymbol.hpp"
 43 #include "ci/ciSymbols.hpp"
 44 #include "ci/ciTypeArray.hpp"
 45 #include "ci/ciTypeArrayKlass.hpp"
 46 #include "ci/ciUtilities.inline.hpp"
 47 #include "ci/ciInlineKlass.hpp"
 48 #include "classfile/javaClasses.inline.hpp"
 49 #include "classfile/vmClasses.hpp"
 50 #include "compiler/compiler_globals.hpp"
 51 #include "gc/shared/collectedHeap.inline.hpp"
 52 #include "memory/allocation.inline.hpp"
 53 #include "memory/universe.hpp"
 54 #include "oops/oop.inline.hpp"
 55 #include "runtime/handles.inline.hpp"
 56 #include "runtime/signature.hpp"
 57 #include "utilities/macros.hpp"
 58 
 59 // ciObjectFactory
 60 //
 61 // This class handles requests for the creation of new instances
 62 // of ciObject and its subclasses.  It contains a caching mechanism
 63 // which ensures that for each oop, at most one ciObject is created.
 64 // This invariant allows more efficient implementation of ciObject.
 65 //
 66 // Implementation note: the oop->ciObject mapping is represented as
 67 // a table stored in an array.  Even though objects are moved
 68 // by the garbage collector, the compactor preserves their relative
 69 // order; address comparison of oops (in perm space) is safe so long
 70 // as we prohibit GC during our comparisons.  We currently use binary
 71 // search to find the oop in the table, and inserting a new oop
 72 // into the table may be costly.  If this cost ends up being
 73 // problematic the underlying data structure can be switched to some
 74 // sort of balanced binary tree.
 75 
 76 GrowableArray<ciMetadata*>* ciObjectFactory::_shared_ci_metadata = NULL;
 77 ciSymbol*                 ciObjectFactory::_shared_ci_symbols[vmSymbols::number_of_symbols()];
 78 int                       ciObjectFactory::_shared_ident_limit = 0;
 79 volatile bool             ciObjectFactory::_initialized = false;
 80 
 81 
 82 // ------------------------------------------------------------------
 83 // ciObjectFactory::ciObjectFactory
 84 ciObjectFactory::ciObjectFactory(Arena* arena,
 85                                  int expected_size)
 86                                  : _arena(arena),
 87                                    _ci_metadata(arena, expected_size, 0, NULL),
 88                                    _unloaded_methods(arena, 4, 0, NULL),
 89                                    _unloaded_klasses(arena, 8, 0, NULL),
 90                                    _unloaded_instances(arena, 4, 0, NULL),
 91                                    _return_addresses(arena, 8, 0, NULL),
 92                                    _symbols(arena, 100, 0, NULL),
 93                                    _next_ident(_shared_ident_limit),
 94                                    _non_perm_count(0) {
 95   for (int i = 0; i < NON_PERM_BUCKETS; i++) {
 96     _non_perm_bucket[i] = NULL;
 97   }
 98 
 99   // If the shared ci objects exist append them to this factory's objects
100   if (_shared_ci_metadata != NULL) {
101     _ci_metadata.appendAll(_shared_ci_metadata);
102   }
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     for (auto index : EnumRange<vmSymbolID>{}) {
131       Symbol* vmsym = vmSymbols::symbol_at(index);
132       assert(vmSymbols::find_sid(vmsym) == index, "1-1 mapping");
133       ciSymbol* sym = new (_arena) ciSymbol(vmsym, index);
134       init_ident_of(sym);
135       _shared_ci_symbols[vmSymbols::as_int(index)] = sym;
136     }
137 #ifdef ASSERT
138     for (auto index : EnumRange<vmSymbolID>{}) {
139       Symbol* vmsym = vmSymbols::symbol_at(index);
140       ciSymbol* sym = vm_symbol_at(index);
141       assert(sym->get_symbol() == vmsym, "oop must match");
142     }
143     assert(ciSymbols::void_class_signature()->get_symbol() == vmSymbols::void_class_signature(), "spot check");
144 #endif
145   }
146 
147   for (int i = T_BOOLEAN; i <= T_CONFLICT; i++) {
148     BasicType t = (BasicType)i;
149     if (type2name(t) != NULL && !is_reference_type(t) &&
150         t != T_NARROWOOP && t != T_NARROWKLASS) {
151       ciType::_basic_types[t] = new (_arena) ciType(t);
152       init_ident_of(ciType::_basic_types[t]);
153     }
154   }
155 
156   ciEnv::_null_object_instance = new (_arena) ciNullObject();
157   init_ident_of(ciEnv::_null_object_instance);
158 
159 #define VM_CLASS_DEFN(name, ignore_s)                              \
160   if (vmClasses::name##_is_loaded()) \
161     ciEnv::_##name = get_metadata(vmClasses::name())->as_instance_klass();
162 
163   VM_CLASSES_DO(VM_CLASS_DEFN)
164 #undef VM_CLASS_DEFN
165 
166   for (int len = -1; len != _ci_metadata.length(); ) {
167     len = _ci_metadata.length();
168     for (int i2 = 0; i2 < len; i2++) {
169       ciMetadata* obj = _ci_metadata.at(i2);
170       assert (obj->is_metadata(), "what else would it be?");
171       if (obj->is_loaded() && obj->is_instance_klass()) {
172         obj->as_instance_klass()->compute_nonstatic_fields();
173       }
174     }
175   }
176 
177   ciEnv::_unloaded_cisymbol = ciObjectFactory::get_symbol(vmSymbols::dummy_symbol());
178   // Create dummy InstanceKlass and ObjArrayKlass object and assign them idents
179   ciEnv::_unloaded_ciinstance_klass = new (_arena) ciInstanceKlass(ciEnv::_unloaded_cisymbol, NULL, NULL);
180   init_ident_of(ciEnv::_unloaded_ciinstance_klass);
181   ciEnv::_unloaded_ciobjarrayklass = new (_arena) ciObjArrayKlass(ciEnv::_unloaded_cisymbol, ciEnv::_unloaded_ciinstance_klass, 1);
182   init_ident_of(ciEnv::_unloaded_ciobjarrayklass);
183   assert(ciEnv::_unloaded_ciobjarrayklass->is_obj_array_klass(), "just checking");
184 
185   get_metadata(Universe::boolArrayKlassObj());
186   get_metadata(Universe::charArrayKlassObj());
187   get_metadata(Universe::floatArrayKlassObj());
188   get_metadata(Universe::doubleArrayKlassObj());
189   get_metadata(Universe::byteArrayKlassObj());
190   get_metadata(Universe::shortArrayKlassObj());
191   get_metadata(Universe::intArrayKlassObj());
192   get_metadata(Universe::longArrayKlassObj());
193 
194   assert(_non_perm_count == 0, "no shared non-perm objects");
195 
196   // The shared_ident_limit is the first ident number that will
197   // be used for non-shared objects.  That is, numbers less than
198   // this limit are permanently assigned to shared CI objects,
199   // while the higher numbers are recycled afresh by each new ciEnv.
200 
201   _shared_ident_limit = _next_ident;
202   _shared_ci_metadata = &_ci_metadata;
203 }
204 
205 
206 ciSymbol* ciObjectFactory::get_symbol(Symbol* key) {
207   vmSymbolID sid = vmSymbols::find_sid(key);
208   if (sid != vmSymbolID::NO_SID) {
209     // do not pollute the main cache with it
210     return vm_symbol_at(sid);
211   }
212 
213   assert(vmSymbols::find_sid(key) == vmSymbolID::NO_SID, "");
214   ciSymbol* s = new (arena()) ciSymbol(key, vmSymbolID::NO_SID);
215   _symbols.push(s);
216   return s;
217 }
218 
219 // Decrement the refcount when done on symbols referenced by this compilation.
220 void ciObjectFactory::remove_symbols() {
221   for (int i = 0; i < _symbols.length(); i++) {
222     ciSymbol* s = _symbols.at(i);
223     s->get_symbol()->decrement_refcount();
224   }
225   // Since _symbols is resource allocated we're not allowed to delete it
226   // but it'll go away just the same.
227 }
228 
229 // ------------------------------------------------------------------
230 // ciObjectFactory::get
231 //
232 // Get the ciObject corresponding to some oop.  If the ciObject has
233 // already been created, it is returned.  Otherwise, a new ciObject
234 // is created.
235 ciObject* ciObjectFactory::get(oop key) {
236   ASSERT_IN_VM;
237 
238   assert(Universe::heap()->is_in(key), "must be");
239 
240   NonPermObject* &bucket = find_non_perm(key);
241   if (bucket != NULL) {
242     return bucket->object();
243   }
244 
245   // The ciObject does not yet exist.  Create it and insert it
246   // into the cache.
247   Handle keyHandle(Thread::current(), key);
248   ciObject* new_object = create_new_object(keyHandle());
249   assert(keyHandle() == new_object->get_oop(), "must be properly recorded");
250   init_ident_of(new_object);
251   assert(Universe::heap()->is_in(new_object->get_oop()), "must be");
252 
253   // Not a perm-space object.
254   insert_non_perm(bucket, keyHandle(), new_object);
255   return new_object;
256 }
257 
258 int ciObjectFactory::metadata_compare(Metadata* const& key, ciMetadata* const& elt) {
259   Metadata* value = elt->constant_encoding();
260   if (key < value)      return -1;
261   else if (key > value) return 1;
262   else                  return 0;
263 }
264 
265 // ------------------------------------------------------------------
266 // ciObjectFactory::cached_metadata
267 //
268 // Get the ciMetadata corresponding to some Metadata. If the ciMetadata has
269 // already been created, it is returned. Otherwise, null is returned.
270 ciMetadata* ciObjectFactory::cached_metadata(Metadata* key) {
271   ASSERT_IN_VM;
272 
273   bool found = false;
274   int index = _ci_metadata.find_sorted<Metadata*, ciObjectFactory::metadata_compare>(key, found);
275 
276   if (!found) {
277     return NULL;
278   }
279   return _ci_metadata.at(index)->as_metadata();
280 }
281 
282 
283 // ------------------------------------------------------------------
284 // ciObjectFactory::get_metadata
285 //
286 // Get the ciMetadata corresponding to some Metadata. If the ciMetadata has
287 // already been created, it is returned. Otherwise, a new ciMetadata
288 // is created.
289 ciMetadata* ciObjectFactory::get_metadata(Metadata* key) {
290   ASSERT_IN_VM;
291 
292 #ifdef ASSERT
293   if (CIObjectFactoryVerify) {
294     Metadata* last = NULL;
295     for (int j = 0; j < _ci_metadata.length(); j++) {
296       Metadata* o = _ci_metadata.at(j)->constant_encoding();
297       assert(last < o, "out of order");
298       last = o;
299     }
300   }
301 #endif // ASSERT
302   int len = _ci_metadata.length();
303   bool found = false;
304   int index = _ci_metadata.find_sorted<Metadata*, ciObjectFactory::metadata_compare>(key, found);
305 #ifdef ASSERT
306   if (CIObjectFactoryVerify) {
307     for (int i = 0; i < _ci_metadata.length(); i++) {
308       if (_ci_metadata.at(i)->constant_encoding() == key) {
309         assert(index == i, " bad lookup");
310       }
311     }
312   }
313 #endif
314 
315   if (!found) {
316     // The ciMetadata does not yet exist. Create it and insert it
317     // into the cache.
318     ciMetadata* new_object = create_new_metadata(key);
319     init_ident_of(new_object);
320     assert(new_object->is_metadata(), "must be");
321 
322     if (len != _ci_metadata.length()) {
323       // creating the new object has recursively entered new objects
324       // into the table.  We need to recompute our index.
325       index = _ci_metadata.find_sorted<Metadata*, ciObjectFactory::metadata_compare>(key, found);
326     }
327     assert(!found, "no double insert");
328     _ci_metadata.insert_before(index, new_object);
329     return new_object;
330   }
331   return _ci_metadata.at(index)->as_metadata();
332 }
333 
334 // ------------------------------------------------------------------
335 // ciObjectFactory::create_new_object
336 //
337 // Create a new ciObject from an oop.
338 //
339 // Implementation note: this functionality could be virtual behavior
340 // of the oop itself.  For now, we explicitly marshal the object.
341 ciObject* ciObjectFactory::create_new_object(oop o) {
342   EXCEPTION_CONTEXT;
343 
344   if (o->is_instance()) {
345     instanceHandle h_i(THREAD, (instanceOop)o);
346     if (java_lang_invoke_CallSite::is_instance(o))
347       return new (arena()) ciCallSite(h_i);
348     else if (java_lang_invoke_MemberName::is_instance(o))
349       return new (arena()) ciMemberName(h_i);
350     else if (jdk_internal_invoke_NativeEntryPoint::is_instance(o))
351       return new (arena()) ciNativeEntryPoint(h_i);
352     else if (java_lang_invoke_MethodHandle::is_instance(o))
353       return new (arena()) ciMethodHandle(h_i);
354     else if (java_lang_invoke_MethodType::is_instance(o))
355       return new (arena()) ciMethodType(h_i);
356     else
357       return new (arena()) ciInstance(h_i);
358   } else if (o->is_objArray()) {
359     objArrayHandle h_oa(THREAD, (objArrayOop)o);
360     return new (arena()) ciObjArray(h_oa);
361   } else if (o->is_typeArray()) {
362     typeArrayHandle h_ta(THREAD, (typeArrayOop)o);
363     return new (arena()) ciTypeArray(h_ta);
364   } else if (o->is_flatArray()) {
365     flatArrayHandle h_ta(THREAD, (flatArrayOop)o);
366     return new (arena()) ciFlatArray(h_ta);
367   }
368 
369   // The oop is of some type not supported by the compiler interface.
370   ShouldNotReachHere();
371   return NULL;
372 }
373 
374 // ------------------------------------------------------------------
375 // ciObjectFactory::create_new_metadata
376 //
377 // Create a new ciMetadata from a Metadata*.
378 //
379 // Implementation note: in order to keep Metadata live, an auxiliary ciObject
380 // is used, which points to it's holder.
381 ciMetadata* ciObjectFactory::create_new_metadata(Metadata* o) {
382   EXCEPTION_CONTEXT;
383 
384   if (o->is_klass()) {
385     Klass* k = (Klass*)o;
386     if (k->is_inline_klass()) {
387       return new (arena()) ciInlineKlass(k);
388     } else if (k->is_instance_klass()) {
389       assert(!ReplayCompiles || ciReplay::no_replay_state() || !ciReplay::is_klass_unresolved((InstanceKlass*)k), "must be whitelisted for replay compilation");
390       return new (arena()) ciInstanceKlass(k);
391     } else if (k->is_flatArray_klass()) {
392       return new (arena()) ciFlatArrayKlass(k);
393     } else if (k->is_objArray_klass()) {
394       return new (arena()) ciObjArrayKlass(k);
395     } else if (k->is_typeArray_klass()) {
396       return new (arena()) ciTypeArrayKlass(k);
397     }
398   } else if (o->is_method()) {
399     methodHandle h_m(THREAD, (Method*)o);
400     ciEnv *env = CURRENT_THREAD_ENV;
401     ciInstanceKlass* holder = env->get_instance_klass(h_m()->method_holder());
402     return new (arena()) ciMethod(h_m, holder);
403   } else if (o->is_methodData()) {
404     // Hold methodHandle alive - might not be necessary ???
405     methodHandle h_m(THREAD, ((MethodData*)o)->method());
406     return new (arena()) ciMethodData((MethodData*)o);
407   }
408 
409   // The Metadata* is of some type not supported by the compiler interface.
410   ShouldNotReachHere();
411   return NULL;
412 }
413 
414 //------------------------------------------------------------------
415 // ciObjectFactory::get_unloaded_method
416 //
417 // Get the ciMethod representing an unloaded/unfound method.
418 //
419 // Implementation note: unloaded methods are currently stored in
420 // an unordered array, requiring a linear-time lookup for each
421 // unloaded method.  This may need to change.
422 ciMethod* ciObjectFactory::get_unloaded_method(ciInstanceKlass* holder,
423                                                ciSymbol*        name,
424                                                ciSymbol*        signature,
425                                                ciInstanceKlass* accessor) {
426   assert(accessor != NULL, "need origin of access");
427   ciSignature* that = NULL;
428   for (int i = 0; i < _unloaded_methods.length(); i++) {
429     ciMethod* entry = _unloaded_methods.at(i);
430     if (entry->holder()->equals(holder) &&
431         entry->name()->equals(name) &&
432         entry->signature()->as_symbol()->equals(signature)) {
433       // Short-circuit slow resolve.
434       if (entry->signature()->accessing_klass() == accessor) {
435         // We've found a match.
436         return entry;
437       } else {
438         // Lazily create ciSignature
439         if (that == NULL)  that = new (arena()) ciSignature(accessor, constantPoolHandle(), signature);
440         if (entry->signature()->equals(that)) {
441           // We've found a match.
442           return entry;
443         }
444       }
445     }
446   }
447 
448   // This is a new unloaded method.  Create it and stick it in
449   // the cache.
450   ciMethod* new_method = new (arena()) ciMethod(holder, name, signature, accessor);
451 
452   init_ident_of(new_method);
453   _unloaded_methods.append(new_method);
454 
455   return new_method;
456 }
457 
458 //------------------------------------------------------------------
459 // ciObjectFactory::get_unloaded_klass
460 //
461 // Get a ciKlass representing an unloaded klass.
462 //
463 // Implementation note: unloaded klasses are currently stored in
464 // an unordered array, requiring a linear-time lookup for each
465 // unloaded klass.  This may need to change.
466 ciKlass* ciObjectFactory::get_unloaded_klass(ciKlass* accessing_klass,
467                                              ciSymbol* name,
468                                              bool create_if_not_found) {
469   EXCEPTION_CONTEXT;
470   oop loader = NULL;
471   oop domain = NULL;
472   if (accessing_klass != NULL) {
473     loader = accessing_klass->loader();
474     domain = accessing_klass->protection_domain();
475   }
476   for (int i = 0; i < _unloaded_klasses.length(); i++) {
477     ciKlass* entry = _unloaded_klasses.at(i);
478     if (entry->name()->equals(name) &&
479         entry->loader() == loader &&
480         entry->protection_domain() == domain) {
481       // We've found a match.
482       return entry;
483     }
484   }
485 
486   if (!create_if_not_found)
487     return NULL;
488 
489   // This is a new unloaded klass.  Create it and stick it in
490   // the cache.
491   ciKlass* new_klass = NULL;
492 
493   // Two cases: this is an unloaded ObjArrayKlass or an
494   // unloaded InstanceKlass.  Deal with both.
495   if (name->char_at(0) == JVM_SIGNATURE_ARRAY) {
496     // Decompose the name.'
497     SignatureStream ss(name->get_symbol(), false);
498     int dimension = ss.skip_array_prefix();  // skip all '['s
499     BasicType element_type = ss.type();
500     assert(element_type != T_ARRAY, "unsuccessful decomposition");
501     ciKlass* element_klass = NULL;
502     if (element_type == T_OBJECT || element_type == T_INLINE_TYPE) {
503       ciEnv *env = CURRENT_THREAD_ENV;
504       ciSymbol* ci_name = env->get_symbol(ss.as_symbol());
505       element_klass =
506         env->get_klass_by_name(accessing_klass, ci_name, false)->as_instance_klass();
507     } else {
508       assert(dimension > 1, "one dimensional type arrays are always loaded.");
509 
510       // The type array itself takes care of one of the dimensions.
511       dimension--;
512 
513       // The element klass is a TypeArrayKlass.
514       element_klass = ciTypeArrayKlass::make(element_type);
515     }
516     new_klass = new (arena()) ciObjArrayKlass(name, element_klass, dimension);
517   } else {
518     jobject loader_handle = NULL;
519     jobject domain_handle = NULL;
520     if (accessing_klass != NULL) {
521       loader_handle = accessing_klass->loader_handle();
522       domain_handle = accessing_klass->protection_domain_handle();
523     }
524     new_klass = new (arena()) ciInstanceKlass(name, loader_handle, domain_handle);
525   }
526   init_ident_of(new_klass);
527   _unloaded_klasses.append(new_klass);
528 
529   return new_klass;
530 }
531 
532 
533 //------------------------------------------------------------------
534 // ciObjectFactory::get_unloaded_instance
535 //
536 // Get a ciInstance representing an as-yet undetermined instance of a given class.
537 //
538 ciInstance* ciObjectFactory::get_unloaded_instance(ciInstanceKlass* instance_klass) {
539   for (int i = 0; i < _unloaded_instances.length(); i++) {
540     ciInstance* entry = _unloaded_instances.at(i);
541     if (entry->klass()->equals(instance_klass)) {
542       // We've found a match.
543       return entry;
544     }
545   }
546 
547   // This is a new unloaded instance.  Create it and stick it in
548   // the cache.
549   ciInstance* new_instance = new (arena()) ciInstance(instance_klass);
550 
551   init_ident_of(new_instance);
552   _unloaded_instances.append(new_instance);
553 
554   // make sure it looks the way we want:
555   assert(!new_instance->is_loaded(), "");
556   assert(new_instance->klass() == instance_klass, "");
557 
558   return new_instance;
559 }
560 
561 
562 //------------------------------------------------------------------
563 // ciObjectFactory::get_unloaded_klass_mirror
564 //
565 // Get a ciInstance representing an unresolved klass mirror.
566 //
567 // Currently, this ignores the parameters and returns a unique unloaded instance.
568 ciInstance* ciObjectFactory::get_unloaded_klass_mirror(ciKlass*  type) {
569   assert(ciEnv::_Class_klass != NULL, "");
570   return get_unloaded_instance(ciEnv::_Class_klass->as_instance_klass());
571 }
572 
573 //------------------------------------------------------------------
574 // ciObjectFactory::get_unloaded_method_handle_constant
575 //
576 // Get a ciInstance representing an unresolved method handle constant.
577 //
578 // Currently, this ignores the parameters and returns a unique unloaded instance.
579 ciInstance* ciObjectFactory::get_unloaded_method_handle_constant(ciKlass*  holder,
580                                                                  ciSymbol* name,
581                                                                  ciSymbol* signature,
582                                                                  int       ref_kind) {
583   if (ciEnv::_MethodHandle_klass == NULL)  return NULL;
584   return get_unloaded_instance(ciEnv::_MethodHandle_klass->as_instance_klass());
585 }
586 
587 //------------------------------------------------------------------
588 // ciObjectFactory::get_unloaded_method_type_constant
589 //
590 // Get a ciInstance representing an unresolved method type constant.
591 //
592 // Currently, this ignores the parameters and returns a unique unloaded instance.
593 ciInstance* ciObjectFactory::get_unloaded_method_type_constant(ciSymbol* signature) {
594   if (ciEnv::_MethodType_klass == NULL)  return NULL;
595   return get_unloaded_instance(ciEnv::_MethodType_klass->as_instance_klass());
596 }
597 
598 ciInstance* ciObjectFactory::get_unloaded_object_constant() {
599   if (ciEnv::_Object_klass == NULL)  return NULL;
600   return get_unloaded_instance(ciEnv::_Object_klass->as_instance_klass());
601 }
602 
603 //------------------------------------------------------------------
604 // ciObjectFactory::get_empty_methodData
605 //
606 // Get the ciMethodData representing the methodData for a method with
607 // none.
608 ciMethodData* ciObjectFactory::get_empty_methodData() {
609   ciMethodData* new_methodData = new (arena()) ciMethodData();
610   init_ident_of(new_methodData);
611   return new_methodData;
612 }
613 
614 //------------------------------------------------------------------
615 // ciObjectFactory::get_return_address
616 //
617 // Get a ciReturnAddress for a specified bci.
618 ciReturnAddress* ciObjectFactory::get_return_address(int bci) {
619   for (int i = 0; i < _return_addresses.length(); i++) {
620     ciReturnAddress* entry = _return_addresses.at(i);
621     if (entry->bci() == bci) {
622       // We've found a match.
623       return entry;
624     }
625   }
626 
627   ciReturnAddress* new_ret_addr = new (arena()) ciReturnAddress(bci);
628   init_ident_of(new_ret_addr);
629   _return_addresses.append(new_ret_addr);
630   return new_ret_addr;
631 }
632 
633 ciWrapper* ciObjectFactory::make_null_free_wrapper(ciType* type) {
634   ciWrapper* wrapper = new (arena()) ciWrapper(type);
635   init_ident_of(wrapper);
636   return wrapper;
637 }
638 
639 // ------------------------------------------------------------------
640 // ciObjectFactory::init_ident_of
641 void ciObjectFactory::init_ident_of(ciBaseObject* obj) {
642   obj->set_ident(_next_ident++);
643 }
644 
645 static ciObjectFactory::NonPermObject* emptyBucket = NULL;
646 
647 // ------------------------------------------------------------------
648 // ciObjectFactory::find_non_perm
649 //
650 // Use a small hash table, hashed on the klass of the key.
651 // If there is no entry in the cache corresponding to this oop, return
652 // the null tail of the bucket into which the oop should be inserted.
653 ciObjectFactory::NonPermObject* &ciObjectFactory::find_non_perm(oop key) {
654   assert(Universe::heap()->is_in(key), "must be");
655   ciMetadata* klass = get_metadata(key->klass());
656   NonPermObject* *bp = &_non_perm_bucket[(unsigned) klass->hash() % NON_PERM_BUCKETS];
657   for (NonPermObject* p; (p = (*bp)) != NULL; bp = &p->next()) {
658     if (is_equal(p, key))  break;
659   }
660   return (*bp);
661 }
662 
663 
664 
665 // ------------------------------------------------------------------
666 // Code for for NonPermObject
667 //
668 inline ciObjectFactory::NonPermObject::NonPermObject(ciObjectFactory::NonPermObject* &bucket, oop key, ciObject* object) {
669   assert(ciObjectFactory::is_initialized(), "");
670   _object = object;
671   _next = bucket;
672   bucket = this;
673 }
674 
675 
676 
677 // ------------------------------------------------------------------
678 // ciObjectFactory::insert_non_perm
679 //
680 // Insert a ciObject into the non-perm table.
681 void ciObjectFactory::insert_non_perm(ciObjectFactory::NonPermObject* &where, oop key, ciObject* obj) {
682   assert(Universe::heap()->is_in_or_null(key), "must be");
683   assert(&where != &emptyBucket, "must not try to fill empty bucket");
684   NonPermObject* p = new (arena()) NonPermObject(where, key, obj);
685   assert(where == p && is_equal(p, key) && p->object() == obj, "entry must match");
686   assert(find_non_perm(key) == p, "must find the same spot");
687   ++_non_perm_count;
688 }
689 
690 // ------------------------------------------------------------------
691 // ciObjectFactory::vm_symbol_at
692 // Get the ciSymbol corresponding to some index in vmSymbols.
693 ciSymbol* ciObjectFactory::vm_symbol_at(vmSymbolID sid) {
694   int index = vmSymbols::as_int(sid);
695   return _shared_ci_symbols[index];
696 }
697 
698 // ------------------------------------------------------------------
699 // ciObjectFactory::metadata_do
700 void ciObjectFactory::metadata_do(MetadataClosure* f) {
701   for (int j = 0; j < _ci_metadata.length(); j++) {
702     Metadata* o = _ci_metadata.at(j)->constant_encoding();
703     f->do_metadata(o);
704   }
705 }
706 
707 // ------------------------------------------------------------------
708 // ciObjectFactory::print_contents_impl
709 void ciObjectFactory::print_contents_impl() {
710   int len = _ci_metadata.length();
711   tty->print_cr("ciObjectFactory (%d) meta data contents:", len);
712   for (int i = 0; i < len; i++) {
713     _ci_metadata.at(i)->print();
714     tty->cr();
715   }
716 }
717 
718 // ------------------------------------------------------------------
719 // ciObjectFactory::print_contents
720 void ciObjectFactory::print_contents() {
721   print();
722   tty->cr();
723   GUARDED_VM_ENTRY(print_contents_impl();)
724 }
725 
726 // ------------------------------------------------------------------
727 // ciObjectFactory::print
728 //
729 // Print debugging information about the object factory
730 void ciObjectFactory::print() {
731   tty->print("<ciObjectFactory oops=%d metadata=%d unloaded_methods=%d unloaded_instances=%d unloaded_klasses=%d>",
732              _non_perm_count, _ci_metadata.length(), _unloaded_methods.length(),
733              _unloaded_instances.length(),
734              _unloaded_klasses.length());
735 }