1 /*
  2  * Copyright (c) 1998, 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 "cds/heapShared.hpp"
 27 #include "classfile/resolutionErrors.hpp"
 28 #include "classfile/systemDictionary.hpp"
 29 #include "classfile/vmClasses.hpp"
 30 #include "code/codeCache.hpp"
 31 #include "interpreter/bytecodeStream.hpp"
 32 #include "interpreter/bytecodes.hpp"
 33 #include "interpreter/interpreter.hpp"
 34 #include "interpreter/linkResolver.hpp"
 35 #include "interpreter/rewriter.hpp"
 36 #include "logging/log.hpp"
 37 #include "logging/logStream.hpp"
 38 #include "memory/metadataFactory.hpp"
 39 #include "memory/metaspaceClosure.hpp"
 40 #include "memory/resourceArea.hpp"
 41 #include "oops/access.inline.hpp"
 42 #include "oops/compressedOops.hpp"
 43 #include "oops/constantPool.inline.hpp"
 44 #include "oops/cpCache.inline.hpp"
 45 #include "oops/objArrayOop.inline.hpp"
 46 #include "oops/oop.inline.hpp"
 47 #include "prims/methodHandles.hpp"
 48 #include "runtime/arguments.hpp"
 49 #include "runtime/atomic.hpp"
 50 #include "runtime/handles.inline.hpp"
 51 #include "runtime/vm_version.hpp"
 52 #include "utilities/macros.hpp"
 53 
 54 // Implementation of ConstantPoolCacheEntry
 55 
 56 void ConstantPoolCacheEntry::initialize_entry(int index) {
 57   assert(0 < index && index < 0x10000, "sanity check");
 58   _indices = index;
 59   _f1 = NULL;
 60   _f2 = _flags = 0;
 61   assert(constant_pool_index() == index, "");
 62 }
 63 
 64 void ConstantPoolCacheEntry::verify_just_initialized(bool f2_used) {
 65   assert((_indices & (~cp_index_mask)) == 0, "sanity");
 66   assert(_f1 == NULL, "sanity");
 67   assert(_flags == 0, "sanity");
 68   if (!f2_used) {
 69     assert(_f2 == 0, "sanity");
 70   }
 71 }
 72 
 73 void ConstantPoolCacheEntry::reinitialize(bool f2_used) {
 74   _indices &= cp_index_mask;
 75   _f1 = NULL;
 76   _flags = 0;
 77   if (!f2_used) {
 78     _f2 = 0;
 79   }
 80 }
 81 
 82 int ConstantPoolCacheEntry::make_flags(TosState state,
 83                                        int option_bits,
 84                                        int field_index_or_method_params) {
 85   assert(state < number_of_states, "Invalid state in make_flags");
 86   int f = ((int)state << tos_state_shift) | option_bits | field_index_or_method_params;
 87   // Preserve existing flag bit values
 88   // The low bits are a field offset, or else the method parameter size.
 89 #ifdef ASSERT
 90   TosState old_state = flag_state();
 91   assert(old_state == (TosState)0 || old_state == state,
 92          "inconsistent cpCache flags state");
 93 #endif
 94   return (_flags | f) ;
 95 }
 96 
 97 void ConstantPoolCacheEntry::set_bytecode_1(Bytecodes::Code code) {
 98 #ifdef ASSERT
 99   // Read once.
100   volatile Bytecodes::Code c = bytecode_1();
101   assert(c == 0 || c == code || code == 0, "update must be consistent");
102 #endif
103   // Need to flush pending stores here before bytecode is written.
104   Atomic::release_store(&_indices, _indices | ((u_char)code << bytecode_1_shift));
105 }
106 
107 void ConstantPoolCacheEntry::set_bytecode_2(Bytecodes::Code code) {
108 #ifdef ASSERT
109   // Read once.
110   volatile Bytecodes::Code c = bytecode_2();
111   assert(c == 0 || c == code || code == 0, "update must be consistent");
112 #endif
113   // Need to flush pending stores here before bytecode is written.
114   Atomic::release_store(&_indices, _indices | ((u_char)code << bytecode_2_shift));
115 }
116 
117 // Sets f1, ordering with previous writes.
118 void ConstantPoolCacheEntry::release_set_f1(Metadata* f1) {
119   assert(f1 != NULL, "");
120   Atomic::release_store(&_f1, f1);
121 }
122 
123 void ConstantPoolCacheEntry::set_indy_resolution_failed() {
124   Atomic::release_store(&_flags, _flags | (1 << indy_resolution_failed_shift));
125 }
126 
127 // Note that concurrent update of both bytecodes can leave one of them
128 // reset to zero.  This is harmless; the interpreter will simply re-resolve
129 // the damaged entry.  More seriously, the memory synchronization is needed
130 // to flush other fields (f1, f2) completely to memory before the bytecodes
131 // are updated, lest other processors see a non-zero bytecode but zero f1/f2.
132 void ConstantPoolCacheEntry::set_field(Bytecodes::Code get_code,
133                                        Bytecodes::Code put_code,
134                                        Klass* field_holder,
135                                        int field_index,
136                                        int field_offset,
137                                        TosState field_type,
138                                        bool is_final,
139                                        bool is_volatile) {
140   set_f1(field_holder);
141   set_f2(field_offset);
142   assert((field_index & field_index_mask) == field_index,
143          "field index does not fit in low flag bits");
144   set_field_flags(field_type,
145                   ((is_volatile ? 1 : 0) << is_volatile_shift) |
146                   ((is_final    ? 1 : 0) << is_final_shift),
147                   field_index);
148   set_bytecode_1(get_code);
149   set_bytecode_2(put_code);
150   NOT_PRODUCT(verify(tty));
151 }
152 
153 void ConstantPoolCacheEntry::set_parameter_size(int value) {
154   // This routine is called only in corner cases where the CPCE is not yet initialized.
155   // See AbstractInterpreter::deopt_continue_after_entry.
156   assert(_flags == 0 || parameter_size() == 0 || parameter_size() == value,
157          "size must not change: parameter_size=%d, value=%d", parameter_size(), value);
158   // Setting the parameter size by itself is only safe if the
159   // current value of _flags is 0, otherwise another thread may have
160   // updated it and we don't want to overwrite that value.  Don't
161   // bother trying to update it once it's nonzero but always make
162   // sure that the final parameter size agrees with what was passed.
163   if (_flags == 0) {
164     intx newflags = (value & parameter_size_mask);
165     Atomic::cmpxchg(&_flags, (intx)0, newflags);
166   }
167   guarantee(parameter_size() == value,
168             "size must not change: parameter_size=%d, value=%d", parameter_size(), value);
169 }
170 
171 void ConstantPoolCacheEntry::set_direct_or_vtable_call(Bytecodes::Code invoke_code,
172                                                        const methodHandle& method,
173                                                        int vtable_index,
174                                                        bool sender_is_interface) {
175   bool is_vtable_call = (vtable_index >= 0);  // FIXME: split this method on this boolean
176   assert(method->interpreter_entry() != NULL, "should have been set at this point");
177   assert(!method->is_obsolete(),  "attempt to write obsolete method to cpCache");
178 
179   int byte_no = -1;
180   bool change_to_virtual = false;
181   InstanceKlass* holder = NULL;  // have to declare this outside the switch
182   switch (invoke_code) {
183     case Bytecodes::_invokeinterface:
184       holder = method->method_holder();
185       // check for private interface method invocations
186       if (vtable_index == Method::nonvirtual_vtable_index && holder->is_interface() ) {
187         assert(method->is_private(), "unexpected non-private method");
188         assert(method->can_be_statically_bound(), "unexpected non-statically-bound method");
189         // set_f2_as_vfinal_method checks if is_vfinal flag is true.
190         set_method_flags(as_TosState(method->result_type()),
191                          (                             1      << is_vfinal_shift) |
192                          ((method->is_final_method() ? 1 : 0) << is_final_shift),
193                          method()->size_of_parameters());
194         set_f2_as_vfinal_method(method());
195         byte_no = 2;
196         set_f1(holder); // interface klass*
197         break;
198       }
199       else {
200         // We get here from InterpreterRuntime::resolve_invoke when an invokeinterface
201         // instruction links to a non-interface method (in Object). This can happen when
202         // an interface redeclares an Object method (like CharSequence declaring toString())
203         // or when invokeinterface is used explicitly.
204         // In that case, the method has no itable index and must be invoked as a virtual.
205         // Set a flag to keep track of this corner case.
206         assert(holder->is_interface() || holder == vmClasses::Object_klass(), "unexpected holder class");
207         assert(method->is_public(), "Calling non-public method in Object with invokeinterface");
208         change_to_virtual = true;
209 
210         // ...and fall through as if we were handling invokevirtual:
211       }
212     case Bytecodes::_invokevirtual:
213       {
214         if (!is_vtable_call) {
215           assert(method->can_be_statically_bound(), "");
216           // set_f2_as_vfinal_method checks if is_vfinal flag is true.
217           set_method_flags(as_TosState(method->result_type()),
218                            (                             1      << is_vfinal_shift) |
219                            ((method->is_final_method() ? 1 : 0) << is_final_shift)  |
220                            ((change_to_virtual         ? 1 : 0) << is_forced_virtual_shift),
221                            method()->size_of_parameters());
222           set_f2_as_vfinal_method(method());
223         } else {
224           assert(!method->can_be_statically_bound(), "");
225           assert(vtable_index >= 0, "valid index");
226           assert(!method->is_final_method(), "sanity");
227           set_method_flags(as_TosState(method->result_type()),
228                            ((change_to_virtual ? 1 : 0) << is_forced_virtual_shift),
229                            method()->size_of_parameters());
230           set_f2(vtable_index);
231         }
232         byte_no = 2;
233         break;
234       }
235 
236     case Bytecodes::_invokespecial:
237     case Bytecodes::_invokestatic:
238       assert(!is_vtable_call, "");
239       // Note:  Read and preserve the value of the is_vfinal flag on any
240       // invokevirtual bytecode shared with this constant pool cache entry.
241       // It is cheap and safe to consult is_vfinal() at all times.
242       // Once is_vfinal is set, it must stay that way, lest we get a dangling oop.
243       set_method_flags(as_TosState(method->result_type()),
244                        ((is_vfinal()               ? 1 : 0) << is_vfinal_shift) |
245                        ((method->is_final_method() ? 1 : 0) << is_final_shift),
246                        method()->size_of_parameters());
247       set_f1(method());
248       byte_no = 1;
249       break;
250     default:
251       ShouldNotReachHere();
252       break;
253   }
254 
255   // Note:  byte_no also appears in TemplateTable::resolve.
256   if (byte_no == 1) {
257     assert(invoke_code != Bytecodes::_invokevirtual &&
258            invoke_code != Bytecodes::_invokeinterface, "");
259     bool do_resolve = true;
260     // Don't mark invokespecial to method as resolved if sender is an interface.  The receiver
261     // has to be checked that it is a subclass of the current class every time this bytecode
262     // is executed.
263     if (invoke_code == Bytecodes::_invokespecial && sender_is_interface &&
264         method->name() != vmSymbols::object_initializer_name()) {
265       do_resolve = false;
266     }
267     if (invoke_code == Bytecodes::_invokestatic) {
268       assert(method->method_holder()->is_initialized() ||
269              method->method_holder()->is_reentrant_initialization(Thread::current()),
270              "invalid class initialization state for invoke_static");
271 
272       if (!VM_Version::supports_fast_class_init_checks() && method->needs_clinit_barrier()) {
273         // Don't mark invokestatic to method as resolved if the holder class has not yet completed
274         // initialization. An invokestatic must only proceed if the class is initialized, but if
275         // we resolve it before then that class initialization check is skipped.
276         //
277         // When fast class initialization checks are supported (VM_Version::supports_fast_class_init_checks() == true),
278         // template interpreter supports fast class initialization check for
279         // invokestatic which doesn't require call site re-resolution to
280         // enforce class initialization barrier.
281         do_resolve = false;
282       }
283     }
284     if (do_resolve) {
285       set_bytecode_1(invoke_code);
286     }
287   } else if (byte_no == 2)  {
288     if (change_to_virtual) {
289       assert(invoke_code == Bytecodes::_invokeinterface, "");
290       // NOTE: THIS IS A HACK - BE VERY CAREFUL!!!
291       //
292       // Workaround for the case where we encounter an invokeinterface, but we
293       // should really have an _invokevirtual since the resolved method is a
294       // virtual method in java.lang.Object. This is a corner case in the spec
295       // but is presumably legal. javac does not generate this code.
296       //
297       // We do not set bytecode_1() to _invokeinterface, because that is the
298       // bytecode # used by the interpreter to see if it is resolved.  In this
299       // case, the method gets reresolved with caller for each interface call
300       // because the actual selected method may not be public.
301       //
302       // We set bytecode_2() to _invokevirtual.
303       // See also interpreterRuntime.cpp. (8/25/2000)
304     } else {
305       assert(invoke_code == Bytecodes::_invokevirtual ||
306              (invoke_code == Bytecodes::_invokeinterface &&
307               ((method->is_private() ||
308                 (method->is_final() && method->method_holder() == vmClasses::Object_klass())))),
309              "unexpected invocation mode");
310       if (invoke_code == Bytecodes::_invokeinterface &&
311           (method->is_private() || method->is_final())) {
312         // We set bytecode_1() to _invokeinterface, because that is the
313         // bytecode # used by the interpreter to see if it is resolved.
314         // We set bytecode_2() to _invokevirtual.
315         set_bytecode_1(invoke_code);
316       }
317     }
318     // set up for invokevirtual, even if linking for invokeinterface also:
319     set_bytecode_2(Bytecodes::_invokevirtual);
320   } else {
321     ShouldNotReachHere();
322   }
323   NOT_PRODUCT(verify(tty));
324 }
325 
326 void ConstantPoolCacheEntry::set_direct_call(Bytecodes::Code invoke_code, const methodHandle& method,
327                                              bool sender_is_interface) {
328   int index = Method::nonvirtual_vtable_index;
329   // index < 0; FIXME: inline and customize set_direct_or_vtable_call
330   set_direct_or_vtable_call(invoke_code, method, index, sender_is_interface);
331 }
332 
333 void ConstantPoolCacheEntry::set_vtable_call(Bytecodes::Code invoke_code, const methodHandle& method, int index) {
334   // either the method is a miranda or its holder should accept the given index
335   assert(method->method_holder()->is_interface() || method->method_holder()->verify_vtable_index(index), "");
336   // index >= 0; FIXME: inline and customize set_direct_or_vtable_call
337   set_direct_or_vtable_call(invoke_code, method, index, false);
338 }
339 
340 void ConstantPoolCacheEntry::set_itable_call(Bytecodes::Code invoke_code,
341                                              Klass* referenced_klass,
342                                              const methodHandle& method, int index) {
343   assert(method->method_holder()->verify_itable_index(index), "");
344   assert(invoke_code == Bytecodes::_invokeinterface, "");
345   InstanceKlass* interf = method->method_holder();
346   assert(interf->is_interface(), "must be an interface");
347   assert(!method->is_final_method(), "interfaces do not have final methods; cannot link to one here");
348   set_f1(referenced_klass);
349   set_f2((intx)method());
350   set_method_flags(as_TosState(method->result_type()),
351                    0,  // no option bits
352                    method()->size_of_parameters());
353   set_bytecode_1(Bytecodes::_invokeinterface);
354 }
355 
356 
357 void ConstantPoolCacheEntry::set_method_handle(const constantPoolHandle& cpool, const CallInfo &call_info) {
358   set_method_handle_common(cpool, Bytecodes::_invokehandle, call_info);
359 }
360 
361 void ConstantPoolCacheEntry::set_dynamic_call(const constantPoolHandle& cpool, const CallInfo &call_info) {
362   set_method_handle_common(cpool, Bytecodes::_invokedynamic, call_info);
363 }
364 
365 void ConstantPoolCacheEntry::set_method_handle_common(const constantPoolHandle& cpool,
366                                                       Bytecodes::Code invoke_code,
367                                                       const CallInfo &call_info) {
368   // NOTE: This CPCE can be the subject of data races.
369   // There are three words to update: flags, refs[f2], f1 (in that order).
370   // Writers must store all other values before f1.
371   // Readers must test f1 first for non-null before reading other fields.
372   // Competing writers must acquire exclusive access via a lock.
373   // A losing writer waits on the lock until the winner writes f1 and leaves
374   // the lock, so that when the losing writer returns, he can use the linked
375   // cache entry.
376 
377   JavaThread* current = JavaThread::current();
378   objArrayHandle resolved_references(current, cpool->resolved_references());
379   // Use the resolved_references() lock for this cpCache entry.
380   // resolved_references are created for all classes with Invokedynamic, MethodHandle
381   // or MethodType constant pool cache entries.
382   assert(resolved_references() != NULL,
383          "a resolved_references array should have been created for this class");
384   ObjectLocker ol(resolved_references, current);
385   if (!is_f1_null()) {
386     return;
387   }
388 
389   if (indy_resolution_failed()) {
390     // Before we got here, another thread got a LinkageError exception during
391     // resolution.  Ignore our success and throw their exception.
392     ConstantPoolCache* cpCache = cpool->cache();
393     int index = -1;
394     for (int i = 0; i < cpCache->length(); i++) {
395       if (cpCache->entry_at(i) == this) {
396         index = i;
397         break;
398       }
399     }
400     guarantee(index >= 0, "Didn't find cpCache entry!");
401     int encoded_index = ResolutionErrorTable::encode_cpcache_index(
402                           ConstantPool::encode_invokedynamic_index(index));
403     JavaThread* THREAD = JavaThread::current(); // For exception macros.
404     ConstantPool::throw_resolution_error(cpool, encoded_index, THREAD);
405     return;
406   }
407 
408   Method* adapter            = call_info.resolved_method();
409   const Handle appendix      = call_info.resolved_appendix();
410   const bool has_appendix    = appendix.not_null();
411 
412   // Write the flags.
413   // MHs and indy are always sig-poly and have a local signature.
414   set_method_flags(as_TosState(adapter->result_type()),
415                    ((has_appendix    ? 1 : 0) << has_appendix_shift        ) |
416                    (                   1      << has_local_signature_shift ) |
417                    (                   1      << is_final_shift            ),
418                    adapter->size_of_parameters());
419 
420   LogStream* log_stream = NULL;
421   LogStreamHandle(Debug, methodhandles, indy) lsh_indy;
422   if (lsh_indy.is_enabled()) {
423     ResourceMark rm;
424     log_stream = &lsh_indy;
425     log_stream->print_cr("set_method_handle bc=%d appendix=" PTR_FORMAT "%s method=" PTR_FORMAT " (local signature) ",
426                          invoke_code,
427                          p2i(appendix()),
428                          (has_appendix ? "" : " (unused)"),
429                          p2i(adapter));
430     adapter->print_on(log_stream);
431     if (has_appendix)  appendix()->print_on(log_stream);
432   }
433 
434   // Method handle invokes and invokedynamic sites use both cp cache words.
435   // refs[f2], if not null, contains a value passed as a trailing argument to the adapter.
436   // In the general case, this could be the call site's MethodType,
437   // for use with java.lang.Invokers.checkExactType, or else a CallSite object.
438   // f1 contains the adapter method which manages the actual call.
439   // In the general case, this is a compiled LambdaForm.
440   // (The Java code is free to optimize these calls by binding other
441   // sorts of methods and appendices to call sites.)
442   // JVM-level linking is via f1, as if for invokespecial, and signatures are erased.
443   // The appendix argument (if any) is added to the signature, and is counted in the parameter_size bits.
444   // Even with the appendix, the method will never take more than 255 parameter slots.
445   //
446   // This means that given a call site like (List)mh.invoke("foo"),
447   // the f1 method has signature '(Ljl/Object;Ljl/invoke/MethodType;)Ljl/Object;',
448   // not '(Ljava/lang/String;)Ljava/util/List;'.
449   // The fact that String and List are involved is encoded in the MethodType in refs[f2].
450   // This allows us to create fewer Methods, while keeping type safety.
451   //
452 
453   // Store appendix, if any.
454   if (has_appendix) {
455     const int appendix_index = f2_as_index();
456     assert(appendix_index >= 0 && appendix_index < resolved_references->length(), "oob");
457     assert(resolved_references->obj_at(appendix_index) == NULL, "init just once");
458     resolved_references->obj_at_put(appendix_index, appendix());
459   }
460 
461   release_set_f1(adapter);  // This must be the last one to set (see NOTE above)!
462 
463   // The interpreter assembly code does not check byte_2,
464   // but it is used by is_resolved, method_if_resolved, etc.
465   set_bytecode_1(invoke_code);
466   NOT_PRODUCT(verify(tty));
467 
468   if (log_stream != NULL) {
469     this->print(log_stream, 0);
470   }
471 
472   assert(has_appendix == this->has_appendix(), "proper storage of appendix flag");
473   assert(this->has_local_signature(), "proper storage of signature flag");
474 }
475 
476 bool ConstantPoolCacheEntry::save_and_throw_indy_exc(
477   const constantPoolHandle& cpool, int cpool_index, int index, constantTag tag, TRAPS) {
478 
479   assert(HAS_PENDING_EXCEPTION, "No exception got thrown!");
480   assert(PENDING_EXCEPTION->is_a(vmClasses::LinkageError_klass()),
481          "No LinkageError exception");
482 
483   // Use the resolved_references() lock for this cpCache entry.
484   // resolved_references are created for all classes with Invokedynamic, MethodHandle
485   // or MethodType constant pool cache entries.
486   JavaThread* current = THREAD;
487   objArrayHandle resolved_references(current, cpool->resolved_references());
488   assert(resolved_references() != NULL,
489          "a resolved_references array should have been created for this class");
490   ObjectLocker ol(resolved_references, current);
491 
492   // if f1 is not null or the indy_resolution_failed flag is set then another
493   // thread either succeeded in resolving the method or got a LinkageError
494   // exception, before this thread was able to record its failure.  So, clear
495   // this thread's exception and return false so caller can use the earlier
496   // thread's result.
497   if (!is_f1_null() || indy_resolution_failed()) {
498     CLEAR_PENDING_EXCEPTION;
499     return false;
500   }
501 
502   Symbol* error = PENDING_EXCEPTION->klass()->name();
503   Symbol* message = java_lang_Throwable::detail_message(PENDING_EXCEPTION);
504 
505   SystemDictionary::add_resolution_error(cpool, index, error, message);
506   set_indy_resolution_failed();
507   return true;
508 }
509 
510 Method* ConstantPoolCacheEntry::method_if_resolved(const constantPoolHandle& cpool) {
511   // Decode the action of set_method and set_interface_call
512   Bytecodes::Code invoke_code = bytecode_1();
513   if (invoke_code != (Bytecodes::Code)0) {
514     Metadata* f1 = f1_ord();
515     if (f1 != NULL) {
516       switch (invoke_code) {
517       case Bytecodes::_invokeinterface:
518         assert(f1->is_klass(), "");
519         return f2_as_interface_method();
520       case Bytecodes::_invokestatic:
521       case Bytecodes::_invokespecial:
522         assert(!has_appendix(), "");
523       case Bytecodes::_invokehandle:
524       case Bytecodes::_invokedynamic:
525         assert(f1->is_method(), "");
526         return (Method*)f1;
527       default:
528         break;
529       }
530     }
531   }
532   invoke_code = bytecode_2();
533   if (invoke_code != (Bytecodes::Code)0) {
534     switch (invoke_code) {
535     case Bytecodes::_invokevirtual:
536       if (is_vfinal()) {
537         // invokevirtual
538         Method* m = f2_as_vfinal_method();
539         assert(m->is_method(), "");
540         return m;
541       } else {
542         int holder_index = cpool->uncached_klass_ref_index_at(constant_pool_index());
543         if (cpool->tag_at(holder_index).is_klass()) {
544           Klass* klass = cpool->resolved_klass_at(holder_index);
545           return klass->method_at_vtable(f2_as_index());
546         }
547       }
548       break;
549     default:
550       break;
551     }
552   }
553   return NULL;
554 }
555 
556 
557 oop ConstantPoolCacheEntry::appendix_if_resolved(const constantPoolHandle& cpool) {
558   if (!has_appendix())
559     return NULL;
560   const int ref_index = f2_as_index();
561   objArrayOop resolved_references = cpool->resolved_references();
562   return resolved_references->obj_at(ref_index);
563 }
564 
565 
566 #if INCLUDE_JVMTI
567 
568 void log_adjust(const char* entry_type, Method* old_method, Method* new_method, bool* trace_name_printed) {
569   ResourceMark rm;
570 
571   if (!(*trace_name_printed)) {
572     log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());
573     *trace_name_printed = true;
574   }
575   log_trace(redefine, class, update, constantpool)
576     ("cpc %s entry update: %s", entry_type, new_method->external_name());
577 }
578 
579 // RedefineClasses() API support:
580 // If this ConstantPoolCacheEntry refers to old_method then update it
581 // to refer to new_method.
582 void ConstantPoolCacheEntry::adjust_method_entry(Method* old_method,
583        Method* new_method, bool * trace_name_printed) {
584 
585   if (is_vfinal()) {
586     // virtual and final so _f2 contains method ptr instead of vtable index
587     if (f2_as_vfinal_method() == old_method) {
588       // match old_method so need an update
589       // NOTE: can't use set_f2_as_vfinal_method as it asserts on different values
590       _f2 = (intptr_t)new_method;
591       log_adjust("vfinal", old_method, new_method, trace_name_printed);
592     }
593     return;
594   }
595 
596   assert (_f1 != NULL, "should not call with uninteresting entry");
597 
598   if (!(_f1->is_method())) {
599     // _f1 is a Klass* for an interface, _f2 is the method
600     if (f2_as_interface_method() == old_method) {
601       _f2 = (intptr_t)new_method;
602       log_adjust("interface", old_method, new_method, trace_name_printed);
603     }
604   } else if (_f1 == old_method) {
605     _f1 = new_method;
606     log_adjust("special, static or dynamic", old_method, new_method, trace_name_printed);
607   }
608 }
609 
610 // a constant pool cache entry should never contain old or obsolete methods
611 bool ConstantPoolCacheEntry::check_no_old_or_obsolete_entries() {
612   Method* m = get_interesting_method_entry();
613   // return false if m refers to a non-deleted old or obsolete method
614   if (m != NULL) {
615     assert(m->is_valid() && m->is_method(), "m is a valid method");
616     return !m->is_old() && !m->is_obsolete(); // old is always set for old and obsolete
617   } else {
618     return true;
619   }
620 }
621 
622 Method* ConstantPoolCacheEntry::get_interesting_method_entry() {
623   if (!is_method_entry()) {
624     // not a method entry so not interesting by default
625     return NULL;
626   }
627   Method* m = NULL;
628   if (is_vfinal()) {
629     // virtual and final so _f2 contains method ptr instead of vtable index
630     m = f2_as_vfinal_method();
631   } else if (is_f1_null()) {
632     // NULL _f1 means this is a virtual entry so also not interesting
633     return NULL;
634   } else {
635     if (!(_f1->is_method())) {
636       // _f1 is a Klass* for an interface
637       m = f2_as_interface_method();
638     } else {
639       m = f1_as_method();
640     }
641   }
642   assert(m != NULL && m->is_method(), "sanity check");
643   if (m == NULL || !m->is_method()) {
644     return NULL;
645   }
646   return m;
647 }
648 #endif // INCLUDE_JVMTI
649 
650 void ConstantPoolCacheEntry::print(outputStream* st, int index) const {
651   // print separator
652   if (index == 0) st->print_cr("                 -------------");
653   // print entry
654   st->print("%3d  (" PTR_FORMAT ")  ", index, (intptr_t)this);
655   st->print_cr("[%02x|%02x|%5d]", bytecode_2(), bytecode_1(),
656                constant_pool_index());
657   st->print_cr("                 [   " PTR_FORMAT "]", (intptr_t)_f1);
658   st->print_cr("                 [   " PTR_FORMAT "]", (intptr_t)_f2);
659   st->print_cr("                 [   " PTR_FORMAT "]", (intptr_t)_flags);
660   st->print_cr("                 -------------");
661 }
662 
663 void ConstantPoolCacheEntry::verify(outputStream* st) const {
664   // not implemented yet
665 }
666 
667 // Implementation of ConstantPoolCache
668 
669 ConstantPoolCache* ConstantPoolCache::allocate(ClassLoaderData* loader_data,
670                                      const intStack& index_map,
671                                      const intStack& invokedynamic_index_map,
672                                      const intStack& invokedynamic_map, TRAPS) {
673 
674   const int length = index_map.length() + invokedynamic_index_map.length();
675   int size = ConstantPoolCache::size(length);
676 
677   return new (loader_data, size, MetaspaceObj::ConstantPoolCacheType, THREAD)
678     ConstantPoolCache(length, index_map, invokedynamic_index_map, invokedynamic_map);
679 }
680 
681 void ConstantPoolCache::initialize(const intArray& inverse_index_map,
682                                    const intArray& invokedynamic_inverse_index_map,
683                                    const intArray& invokedynamic_references_map) {
684   for (int i = 0; i < inverse_index_map.length(); i++) {
685     ConstantPoolCacheEntry* e = entry_at(i);
686     int original_index = inverse_index_map.at(i);
687     e->initialize_entry(original_index);
688     assert(entry_at(i) == e, "sanity");
689   }
690 
691   // Append invokedynamic entries at the end
692   int invokedynamic_offset = inverse_index_map.length();
693   for (int i = 0; i < invokedynamic_inverse_index_map.length(); i++) {
694     int offset = i + invokedynamic_offset;
695     ConstantPoolCacheEntry* e = entry_at(offset);
696     int original_index = invokedynamic_inverse_index_map.at(i);
697     e->initialize_entry(original_index);
698     assert(entry_at(offset) == e, "sanity");
699   }
700 
701   for (int ref = 0; ref < invokedynamic_references_map.length(); ref++) {
702     const int cpci = invokedynamic_references_map.at(ref);
703     if (cpci >= 0) {
704       entry_at(cpci)->initialize_resolved_reference_index(ref);
705     }
706   }
707 }
708 
709 // Record the GC marking cycle when redefined vs. when found in the InstanceStackChunks.
710 void ConstantPoolCache::record_marking_cycle() {
711   _marking_cycle = CodeCache::marking_cycle();
712 }
713 
714 void ConstantPoolCache::verify_just_initialized() {
715   DEBUG_ONLY(walk_entries_for_initialization(/*check_only = */ true));
716 }
717 
718 void ConstantPoolCache::remove_unshareable_info() {
719   walk_entries_for_initialization(/*check_only = */ false);
720 }
721 
722 void ConstantPoolCache::walk_entries_for_initialization(bool check_only) {
723   Arguments::assert_is_dumping_archive();
724   // When dumping the archive, we want to clean up the ConstantPoolCache
725   // to remove any effect of linking due to the execution of Java code --
726   // each ConstantPoolCacheEntry will have the same contents as if
727   // ConstantPoolCache::initialize has just returned:
728   //
729   // - We keep the ConstantPoolCache::constant_pool_index() bits for all entries.
730   // - We keep the "f2" field for entries used by invokedynamic and invokehandle
731   // - All other bits in the entries are cleared to zero.
732   ResourceMark rm;
733 
734   InstanceKlass* ik = constant_pool()->pool_holder();
735   bool* f2_used = NEW_RESOURCE_ARRAY(bool, length());
736   memset(f2_used, 0, sizeof(bool) * length());
737 
738   Thread* current = Thread::current();
739 
740   // Find all the slots that we need to preserve f2
741   for (int i = 0; i < ik->methods()->length(); i++) {
742     Method* m = ik->methods()->at(i);
743     RawBytecodeStream bcs(methodHandle(current, m));
744     while (!bcs.is_last_bytecode()) {
745       Bytecodes::Code opcode = bcs.raw_next();
746       switch (opcode) {
747       case Bytecodes::_invokedynamic: {
748           int index = Bytes::get_native_u4(bcs.bcp() + 1);
749           int cp_cache_index = constant_pool()->invokedynamic_cp_cache_index(index);
750           f2_used[cp_cache_index] = 1;
751         }
752         break;
753       case Bytecodes::_invokehandle: {
754           int cp_cache_index = Bytes::get_native_u2(bcs.bcp() + 1);
755           f2_used[cp_cache_index] = 1;
756         }
757         break;
758       default:
759         break;
760       }
761     }
762   }
763 
764   if (check_only) {
765     DEBUG_ONLY(
766       for (int i=0; i<length(); i++) {
767         entry_at(i)->verify_just_initialized(f2_used[i]);
768       })
769   } else {
770     for (int i=0; i<length(); i++) {
771       entry_at(i)->reinitialize(f2_used[i]);
772     }
773   }
774 }
775 
776 void ConstantPoolCache::deallocate_contents(ClassLoaderData* data) {
777   assert(!is_shared(), "shared caches are not deallocated");
778   data->remove_handle(_resolved_references);
779   set_resolved_references(OopHandle());
780   MetadataFactory::free_array<u2>(data, _reference_map);
781   set_reference_map(NULL);
782 }
783 
784 #if INCLUDE_CDS_JAVA_HEAP
785 oop ConstantPoolCache::archived_references() {
786   if (_archived_references_index < 0) {
787     return NULL;
788   }
789   return HeapShared::get_root(_archived_references_index);
790 }
791 
792 void ConstantPoolCache::clear_archived_references() {
793   if (_archived_references_index >= 0) {
794     HeapShared::clear_root(_archived_references_index);
795     _archived_references_index = -1;
796   }
797 }
798 
799 void ConstantPoolCache::set_archived_references(oop o) {
800   assert(DumpSharedSpaces, "called only during runtime");
801   _archived_references_index = HeapShared::append_root(o);
802 }
803 #endif
804 
805 #if INCLUDE_JVMTI
806 // RedefineClasses() API support:
807 // If any entry of this ConstantPoolCache points to any of
808 // old_methods, replace it with the corresponding new_method.
809 void ConstantPoolCache::adjust_method_entries(bool * trace_name_printed) {
810   for (int i = 0; i < length(); i++) {
811     ConstantPoolCacheEntry* entry = entry_at(i);
812     Method* old_method = entry->get_interesting_method_entry();
813     if (old_method == NULL || !old_method->is_old()) {
814       continue; // skip uninteresting entries
815     }
816     if (old_method->is_deleted()) {
817       // clean up entries with deleted methods
818       entry->initialize_entry(entry->constant_pool_index());
819       continue;
820     }
821     Method* new_method = old_method->get_new_method();
822     entry_at(i)->adjust_method_entry(old_method, new_method, trace_name_printed);
823   }
824 }
825 
826 // the constant pool cache should never contain old or obsolete methods
827 bool ConstantPoolCache::check_no_old_or_obsolete_entries() {
828   ResourceMark rm;
829   for (int i = 1; i < length(); i++) {
830     Method* m = entry_at(i)->get_interesting_method_entry();
831     if (m != NULL && !entry_at(i)->check_no_old_or_obsolete_entries()) {
832       log_trace(redefine, class, update, constantpool)
833         ("cpcache check found old method entry: class: %s, old: %d, obsolete: %d, method: %s",
834          constant_pool()->pool_holder()->external_name(), m->is_old(), m->is_obsolete(), m->external_name());
835       return false;
836     }
837   }
838   return true;
839 }
840 
841 void ConstantPoolCache::dump_cache() {
842   for (int i = 1; i < length(); i++) {
843     if (entry_at(i)->get_interesting_method_entry() != NULL) {
844       entry_at(i)->print(tty, i);
845     }
846   }
847 }
848 #endif // INCLUDE_JVMTI
849 
850 void ConstantPoolCache::metaspace_pointers_do(MetaspaceClosure* it) {
851   log_trace(cds)("Iter(ConstantPoolCache): %p", this);
852   it->push(&_constant_pool);
853   it->push(&_reference_map);
854 }
855 
856 // Printing
857 
858 void ConstantPoolCache::print_on(outputStream* st) const {
859   st->print_cr("%s", internal_name());
860   // print constant pool cache entries
861   for (int i = 0; i < length(); i++) entry_at(i)->print(st, i);
862 }
863 
864 void ConstantPoolCache::print_value_on(outputStream* st) const {
865   st->print("cache [%d]", length());
866   print_address_on(st);
867   st->print(" for ");
868   constant_pool()->print_value_on(st);
869 }
870 
871 
872 // Verification
873 
874 void ConstantPoolCache::verify_on(outputStream* st) {
875   // print constant pool cache entries
876   for (int i = 0; i < length(); i++) entry_at(i)->verify(st);
877 }