src/share/vm/oops/instanceKlass.cpp

Tue, 29 Mar 2011 22:05:21 -0700

author
never
date
Tue, 29 Mar 2011 22:05:21 -0700
changeset 2690
2cd0180da6e1
parent 2658
c7f3d0b4570f
child 2945
d3b9f2be46ab
permissions
-rw-r--r--

7032306: Fastdebug build failure on Solaris with SS11 compilers
Reviewed-by: kvn, iveresov

     1 /*
     2  * Copyright (c) 1997, 2011, 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  */
    25 #include "precompiled.hpp"
    26 #include "classfile/javaClasses.hpp"
    27 #include "classfile/systemDictionary.hpp"
    28 #include "classfile/verifier.hpp"
    29 #include "classfile/vmSymbols.hpp"
    30 #include "compiler/compileBroker.hpp"
    31 #include "gc_implementation/shared/markSweep.inline.hpp"
    32 #include "gc_interface/collectedHeap.inline.hpp"
    33 #include "interpreter/oopMapCache.hpp"
    34 #include "interpreter/rewriter.hpp"
    35 #include "jvmtifiles/jvmti.h"
    36 #include "memory/genOopClosures.inline.hpp"
    37 #include "memory/oopFactory.hpp"
    38 #include "memory/permGen.hpp"
    39 #include "oops/instanceKlass.hpp"
    40 #include "oops/instanceMirrorKlass.hpp"
    41 #include "oops/instanceOop.hpp"
    42 #include "oops/methodOop.hpp"
    43 #include "oops/objArrayKlassKlass.hpp"
    44 #include "oops/oop.inline.hpp"
    45 #include "oops/symbol.hpp"
    46 #include "prims/jvmtiExport.hpp"
    47 #include "prims/jvmtiRedefineClassesTrace.hpp"
    48 #include "runtime/fieldDescriptor.hpp"
    49 #include "runtime/handles.inline.hpp"
    50 #include "runtime/javaCalls.hpp"
    51 #include "runtime/mutexLocker.hpp"
    52 #include "services/threadService.hpp"
    53 #include "utilities/dtrace.hpp"
    54 #ifdef TARGET_OS_FAMILY_linux
    55 # include "thread_linux.inline.hpp"
    56 #endif
    57 #ifdef TARGET_OS_FAMILY_solaris
    58 # include "thread_solaris.inline.hpp"
    59 #endif
    60 #ifdef TARGET_OS_FAMILY_windows
    61 # include "thread_windows.inline.hpp"
    62 #endif
    63 #ifndef SERIALGC
    64 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
    65 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
    66 #include "gc_implementation/g1/g1RemSet.inline.hpp"
    67 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
    68 #include "gc_implementation/parNew/parOopClosures.inline.hpp"
    69 #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"
    70 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
    71 #include "oops/oop.pcgc.inline.hpp"
    72 #endif
    73 #ifdef COMPILER1
    74 #include "c1/c1_Compiler.hpp"
    75 #endif
    77 #ifdef DTRACE_ENABLED
    79 HS_DTRACE_PROBE_DECL4(hotspot, class__initialization__required,
    80   char*, intptr_t, oop, intptr_t);
    81 HS_DTRACE_PROBE_DECL5(hotspot, class__initialization__recursive,
    82   char*, intptr_t, oop, intptr_t, int);
    83 HS_DTRACE_PROBE_DECL5(hotspot, class__initialization__concurrent,
    84   char*, intptr_t, oop, intptr_t, int);
    85 HS_DTRACE_PROBE_DECL5(hotspot, class__initialization__erroneous,
    86   char*, intptr_t, oop, intptr_t, int);
    87 HS_DTRACE_PROBE_DECL5(hotspot, class__initialization__super__failed,
    88   char*, intptr_t, oop, intptr_t, int);
    89 HS_DTRACE_PROBE_DECL5(hotspot, class__initialization__clinit,
    90   char*, intptr_t, oop, intptr_t, int);
    91 HS_DTRACE_PROBE_DECL5(hotspot, class__initialization__error,
    92   char*, intptr_t, oop, intptr_t, int);
    93 HS_DTRACE_PROBE_DECL5(hotspot, class__initialization__end,
    94   char*, intptr_t, oop, intptr_t, int);
    96 #define DTRACE_CLASSINIT_PROBE(type, clss, thread_type)          \
    97   {                                                              \
    98     char* data = NULL;                                           \
    99     int len = 0;                                                 \
   100     Symbol* name = (clss)->name();                               \
   101     if (name != NULL) {                                          \
   102       data = (char*)name->bytes();                               \
   103       len = name->utf8_length();                                 \
   104     }                                                            \
   105     HS_DTRACE_PROBE4(hotspot, class__initialization__##type,     \
   106       data, len, (clss)->class_loader(), thread_type);           \
   107   }
   109 #define DTRACE_CLASSINIT_PROBE_WAIT(type, clss, thread_type, wait) \
   110   {                                                              \
   111     char* data = NULL;                                           \
   112     int len = 0;                                                 \
   113     Symbol* name = (clss)->name();                               \
   114     if (name != NULL) {                                          \
   115       data = (char*)name->bytes();                               \
   116       len = name->utf8_length();                                 \
   117     }                                                            \
   118     HS_DTRACE_PROBE5(hotspot, class__initialization__##type,     \
   119       data, len, (clss)->class_loader(), thread_type, wait);     \
   120   }
   122 #else //  ndef DTRACE_ENABLED
   124 #define DTRACE_CLASSINIT_PROBE(type, clss, thread_type)
   125 #define DTRACE_CLASSINIT_PROBE_WAIT(type, clss, thread_type, wait)
   127 #endif //  ndef DTRACE_ENABLED
   129 bool instanceKlass::should_be_initialized() const {
   130   return !is_initialized();
   131 }
   133 klassVtable* instanceKlass::vtable() const {
   134   return new klassVtable(as_klassOop(), start_of_vtable(), vtable_length() / vtableEntry::size());
   135 }
   137 klassItable* instanceKlass::itable() const {
   138   return new klassItable(as_klassOop());
   139 }
   141 void instanceKlass::eager_initialize(Thread *thread) {
   142   if (!EagerInitialization) return;
   144   if (this->is_not_initialized()) {
   145     // abort if the the class has a class initializer
   146     if (this->class_initializer() != NULL) return;
   148     // abort if it is java.lang.Object (initialization is handled in genesis)
   149     klassOop super = this->super();
   150     if (super == NULL) return;
   152     // abort if the super class should be initialized
   153     if (!instanceKlass::cast(super)->is_initialized()) return;
   155     // call body to expose the this pointer
   156     instanceKlassHandle this_oop(thread, this->as_klassOop());
   157     eager_initialize_impl(this_oop);
   158   }
   159 }
   162 void instanceKlass::eager_initialize_impl(instanceKlassHandle this_oop) {
   163   EXCEPTION_MARK;
   164   ObjectLocker ol(this_oop, THREAD);
   166   // abort if someone beat us to the initialization
   167   if (!this_oop->is_not_initialized()) return;  // note: not equivalent to is_initialized()
   169   ClassState old_state = this_oop->_init_state;
   170   link_class_impl(this_oop, true, THREAD);
   171   if (HAS_PENDING_EXCEPTION) {
   172     CLEAR_PENDING_EXCEPTION;
   173     // Abort if linking the class throws an exception.
   175     // Use a test to avoid redundantly resetting the state if there's
   176     // no change.  Set_init_state() asserts that state changes make
   177     // progress, whereas here we might just be spinning in place.
   178     if( old_state != this_oop->_init_state )
   179       this_oop->set_init_state (old_state);
   180   } else {
   181     // linking successfull, mark class as initialized
   182     this_oop->set_init_state (fully_initialized);
   183     // trace
   184     if (TraceClassInitialization) {
   185       ResourceMark rm(THREAD);
   186       tty->print_cr("[Initialized %s without side effects]", this_oop->external_name());
   187     }
   188   }
   189 }
   192 // See "The Virtual Machine Specification" section 2.16.5 for a detailed explanation of the class initialization
   193 // process. The step comments refers to the procedure described in that section.
   194 // Note: implementation moved to static method to expose the this pointer.
   195 void instanceKlass::initialize(TRAPS) {
   196   if (this->should_be_initialized()) {
   197     HandleMark hm(THREAD);
   198     instanceKlassHandle this_oop(THREAD, this->as_klassOop());
   199     initialize_impl(this_oop, CHECK);
   200     // Note: at this point the class may be initialized
   201     //       OR it may be in the state of being initialized
   202     //       in case of recursive initialization!
   203   } else {
   204     assert(is_initialized(), "sanity check");
   205   }
   206 }
   209 bool instanceKlass::verify_code(
   210     instanceKlassHandle this_oop, bool throw_verifyerror, TRAPS) {
   211   // 1) Verify the bytecodes
   212   Verifier::Mode mode =
   213     throw_verifyerror ? Verifier::ThrowException : Verifier::NoException;
   214   return Verifier::verify(this_oop, mode, this_oop->should_verify_class(), CHECK_false);
   215 }
   218 // Used exclusively by the shared spaces dump mechanism to prevent
   219 // classes mapped into the shared regions in new VMs from appearing linked.
   221 void instanceKlass::unlink_class() {
   222   assert(is_linked(), "must be linked");
   223   _init_state = loaded;
   224 }
   226 void instanceKlass::link_class(TRAPS) {
   227   assert(is_loaded(), "must be loaded");
   228   if (!is_linked()) {
   229     instanceKlassHandle this_oop(THREAD, this->as_klassOop());
   230     link_class_impl(this_oop, true, CHECK);
   231   }
   232 }
   234 // Called to verify that a class can link during initialization, without
   235 // throwing a VerifyError.
   236 bool instanceKlass::link_class_or_fail(TRAPS) {
   237   assert(is_loaded(), "must be loaded");
   238   if (!is_linked()) {
   239     instanceKlassHandle this_oop(THREAD, this->as_klassOop());
   240     link_class_impl(this_oop, false, CHECK_false);
   241   }
   242   return is_linked();
   243 }
   245 bool instanceKlass::link_class_impl(
   246     instanceKlassHandle this_oop, bool throw_verifyerror, TRAPS) {
   247   // check for error state
   248   if (this_oop->is_in_error_state()) {
   249     ResourceMark rm(THREAD);
   250     THROW_MSG_(vmSymbols::java_lang_NoClassDefFoundError(),
   251                this_oop->external_name(), false);
   252   }
   253   // return if already verified
   254   if (this_oop->is_linked()) {
   255     return true;
   256   }
   258   // Timing
   259   // timer handles recursion
   260   assert(THREAD->is_Java_thread(), "non-JavaThread in link_class_impl");
   261   JavaThread* jt = (JavaThread*)THREAD;
   263   // link super class before linking this class
   264   instanceKlassHandle super(THREAD, this_oop->super());
   265   if (super.not_null()) {
   266     if (super->is_interface()) {  // check if super class is an interface
   267       ResourceMark rm(THREAD);
   268       Exceptions::fthrow(
   269         THREAD_AND_LOCATION,
   270         vmSymbols::java_lang_IncompatibleClassChangeError(),
   271         "class %s has interface %s as super class",
   272         this_oop->external_name(),
   273         super->external_name()
   274       );
   275       return false;
   276     }
   278     link_class_impl(super, throw_verifyerror, CHECK_false);
   279   }
   281   // link all interfaces implemented by this class before linking this class
   282   objArrayHandle interfaces (THREAD, this_oop->local_interfaces());
   283   int num_interfaces = interfaces->length();
   284   for (int index = 0; index < num_interfaces; index++) {
   285     HandleMark hm(THREAD);
   286     instanceKlassHandle ih(THREAD, klassOop(interfaces->obj_at(index)));
   287     link_class_impl(ih, throw_verifyerror, CHECK_false);
   288   }
   290   // in case the class is linked in the process of linking its superclasses
   291   if (this_oop->is_linked()) {
   292     return true;
   293   }
   295   // trace only the link time for this klass that includes
   296   // the verification time
   297   PerfClassTraceTime vmtimer(ClassLoader::perf_class_link_time(),
   298                              ClassLoader::perf_class_link_selftime(),
   299                              ClassLoader::perf_classes_linked(),
   300                              jt->get_thread_stat()->perf_recursion_counts_addr(),
   301                              jt->get_thread_stat()->perf_timers_addr(),
   302                              PerfClassTraceTime::CLASS_LINK);
   304   // verification & rewriting
   305   {
   306     ObjectLocker ol(this_oop, THREAD);
   307     // rewritten will have been set if loader constraint error found
   308     // on an earlier link attempt
   309     // don't verify or rewrite if already rewritten
   310     if (!this_oop->is_linked()) {
   311       if (!this_oop->is_rewritten()) {
   312         {
   313           // Timer includes any side effects of class verification (resolution,
   314           // etc), but not recursive entry into verify_code().
   315           PerfClassTraceTime timer(ClassLoader::perf_class_verify_time(),
   316                                    ClassLoader::perf_class_verify_selftime(),
   317                                    ClassLoader::perf_classes_verified(),
   318                                    jt->get_thread_stat()->perf_recursion_counts_addr(),
   319                                    jt->get_thread_stat()->perf_timers_addr(),
   320                                    PerfClassTraceTime::CLASS_VERIFY);
   321           bool verify_ok = verify_code(this_oop, throw_verifyerror, THREAD);
   322           if (!verify_ok) {
   323             return false;
   324           }
   325         }
   327         // Just in case a side-effect of verify linked this class already
   328         // (which can sometimes happen since the verifier loads classes
   329         // using custom class loaders, which are free to initialize things)
   330         if (this_oop->is_linked()) {
   331           return true;
   332         }
   334         // also sets rewritten
   335         this_oop->rewrite_class(CHECK_false);
   336       }
   338       // Initialize the vtable and interface table after
   339       // methods have been rewritten since rewrite may
   340       // fabricate new methodOops.
   341       // also does loader constraint checking
   342       if (!this_oop()->is_shared()) {
   343         ResourceMark rm(THREAD);
   344         this_oop->vtable()->initialize_vtable(true, CHECK_false);
   345         this_oop->itable()->initialize_itable(true, CHECK_false);
   346       }
   347 #ifdef ASSERT
   348       else {
   349         ResourceMark rm(THREAD);
   350         this_oop->vtable()->verify(tty, true);
   351         // In case itable verification is ever added.
   352         // this_oop->itable()->verify(tty, true);
   353       }
   354 #endif
   355       this_oop->set_init_state(linked);
   356       if (JvmtiExport::should_post_class_prepare()) {
   357         Thread *thread = THREAD;
   358         assert(thread->is_Java_thread(), "thread->is_Java_thread()");
   359         JvmtiExport::post_class_prepare((JavaThread *) thread, this_oop());
   360       }
   361     }
   362   }
   363   return true;
   364 }
   367 // Rewrite the byte codes of all of the methods of a class.
   368 // Three cases:
   369 //    During the link of a newly loaded class.
   370 //    During the preloading of classes to be written to the shared spaces.
   371 //      - Rewrite the methods and update the method entry points.
   372 //
   373 //    During the link of a class in the shared spaces.
   374 //      - The methods were already rewritten, update the metho entry points.
   375 //
   376 // The rewriter must be called exactly once. Rewriting must happen after
   377 // verification but before the first method of the class is executed.
   379 void instanceKlass::rewrite_class(TRAPS) {
   380   assert(is_loaded(), "must be loaded");
   381   instanceKlassHandle this_oop(THREAD, this->as_klassOop());
   382   if (this_oop->is_rewritten()) {
   383     assert(this_oop()->is_shared(), "rewriting an unshared class?");
   384     return;
   385   }
   386   Rewriter::rewrite(this_oop, CHECK); // No exception can happen here
   387   this_oop->set_rewritten();
   388 }
   391 void instanceKlass::initialize_impl(instanceKlassHandle this_oop, TRAPS) {
   392   // Make sure klass is linked (verified) before initialization
   393   // A class could already be verified, since it has been reflected upon.
   394   this_oop->link_class(CHECK);
   396   DTRACE_CLASSINIT_PROBE(required, instanceKlass::cast(this_oop()), -1);
   398   bool wait = false;
   400   // refer to the JVM book page 47 for description of steps
   401   // Step 1
   402   { ObjectLocker ol(this_oop, THREAD);
   404     Thread *self = THREAD; // it's passed the current thread
   406     // Step 2
   407     // If we were to use wait() instead of waitInterruptibly() then
   408     // we might end up throwing IE from link/symbol resolution sites
   409     // that aren't expected to throw.  This would wreak havoc.  See 6320309.
   410     while(this_oop->is_being_initialized() && !this_oop->is_reentrant_initialization(self)) {
   411         wait = true;
   412       ol.waitUninterruptibly(CHECK);
   413     }
   415     // Step 3
   416     if (this_oop->is_being_initialized() && this_oop->is_reentrant_initialization(self)) {
   417       DTRACE_CLASSINIT_PROBE_WAIT(recursive, instanceKlass::cast(this_oop()), -1,wait);
   418       return;
   419     }
   421     // Step 4
   422     if (this_oop->is_initialized()) {
   423       DTRACE_CLASSINIT_PROBE_WAIT(concurrent, instanceKlass::cast(this_oop()), -1,wait);
   424       return;
   425     }
   427     // Step 5
   428     if (this_oop->is_in_error_state()) {
   429       DTRACE_CLASSINIT_PROBE_WAIT(erroneous, instanceKlass::cast(this_oop()), -1,wait);
   430       ResourceMark rm(THREAD);
   431       const char* desc = "Could not initialize class ";
   432       const char* className = this_oop->external_name();
   433       size_t msglen = strlen(desc) + strlen(className) + 1;
   434       char* message = NEW_RESOURCE_ARRAY(char, msglen);
   435       if (NULL == message) {
   436         // Out of memory: can't create detailed error message
   437         THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), className);
   438       } else {
   439         jio_snprintf(message, msglen, "%s%s", desc, className);
   440         THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), message);
   441       }
   442     }
   444     // Step 6
   445     this_oop->set_init_state(being_initialized);
   446     this_oop->set_init_thread(self);
   447   }
   449   // Step 7
   450   klassOop super_klass = this_oop->super();
   451   if (super_klass != NULL && !this_oop->is_interface() && Klass::cast(super_klass)->should_be_initialized()) {
   452     Klass::cast(super_klass)->initialize(THREAD);
   454     if (HAS_PENDING_EXCEPTION) {
   455       Handle e(THREAD, PENDING_EXCEPTION);
   456       CLEAR_PENDING_EXCEPTION;
   457       {
   458         EXCEPTION_MARK;
   459         this_oop->set_initialization_state_and_notify(initialization_error, THREAD); // Locks object, set state, and notify all waiting threads
   460         CLEAR_PENDING_EXCEPTION;   // ignore any exception thrown, superclass initialization error is thrown below
   461       }
   462       DTRACE_CLASSINIT_PROBE_WAIT(super__failed, instanceKlass::cast(this_oop()), -1,wait);
   463       THROW_OOP(e());
   464     }
   465   }
   467   // Step 8
   468   {
   469     assert(THREAD->is_Java_thread(), "non-JavaThread in initialize_impl");
   470     JavaThread* jt = (JavaThread*)THREAD;
   471     DTRACE_CLASSINIT_PROBE_WAIT(clinit, instanceKlass::cast(this_oop()), -1,wait);
   472     // Timer includes any side effects of class initialization (resolution,
   473     // etc), but not recursive entry into call_class_initializer().
   474     PerfClassTraceTime timer(ClassLoader::perf_class_init_time(),
   475                              ClassLoader::perf_class_init_selftime(),
   476                              ClassLoader::perf_classes_inited(),
   477                              jt->get_thread_stat()->perf_recursion_counts_addr(),
   478                              jt->get_thread_stat()->perf_timers_addr(),
   479                              PerfClassTraceTime::CLASS_CLINIT);
   480     this_oop->call_class_initializer(THREAD);
   481   }
   483   // Step 9
   484   if (!HAS_PENDING_EXCEPTION) {
   485     this_oop->set_initialization_state_and_notify(fully_initialized, CHECK);
   486     { ResourceMark rm(THREAD);
   487       debug_only(this_oop->vtable()->verify(tty, true);)
   488     }
   489   }
   490   else {
   491     // Step 10 and 11
   492     Handle e(THREAD, PENDING_EXCEPTION);
   493     CLEAR_PENDING_EXCEPTION;
   494     {
   495       EXCEPTION_MARK;
   496       this_oop->set_initialization_state_and_notify(initialization_error, THREAD);
   497       CLEAR_PENDING_EXCEPTION;   // ignore any exception thrown, class initialization error is thrown below
   498     }
   499     DTRACE_CLASSINIT_PROBE_WAIT(error, instanceKlass::cast(this_oop()), -1,wait);
   500     if (e->is_a(SystemDictionary::Error_klass())) {
   501       THROW_OOP(e());
   502     } else {
   503       JavaCallArguments args(e);
   504       THROW_ARG(vmSymbols::java_lang_ExceptionInInitializerError(),
   505                 vmSymbols::throwable_void_signature(),
   506                 &args);
   507     }
   508   }
   509   DTRACE_CLASSINIT_PROBE_WAIT(end, instanceKlass::cast(this_oop()), -1,wait);
   510 }
   513 // Note: implementation moved to static method to expose the this pointer.
   514 void instanceKlass::set_initialization_state_and_notify(ClassState state, TRAPS) {
   515   instanceKlassHandle kh(THREAD, this->as_klassOop());
   516   set_initialization_state_and_notify_impl(kh, state, CHECK);
   517 }
   519 void instanceKlass::set_initialization_state_and_notify_impl(instanceKlassHandle this_oop, ClassState state, TRAPS) {
   520   ObjectLocker ol(this_oop, THREAD);
   521   this_oop->set_init_state(state);
   522   ol.notify_all(CHECK);
   523 }
   525 void instanceKlass::add_implementor(klassOop k) {
   526   assert(Compile_lock->owned_by_self(), "");
   527   // Filter out my subinterfaces.
   528   // (Note: Interfaces are never on the subklass list.)
   529   if (instanceKlass::cast(k)->is_interface()) return;
   531   // Filter out subclasses whose supers already implement me.
   532   // (Note: CHA must walk subclasses of direct implementors
   533   // in order to locate indirect implementors.)
   534   klassOop sk = instanceKlass::cast(k)->super();
   535   if (sk != NULL && instanceKlass::cast(sk)->implements_interface(as_klassOop()))
   536     // We only need to check one immediate superclass, since the
   537     // implements_interface query looks at transitive_interfaces.
   538     // Any supers of the super have the same (or fewer) transitive_interfaces.
   539     return;
   541   // Update number of implementors
   542   int i = _nof_implementors++;
   544   // Record this implementor, if there are not too many already
   545   if (i < implementors_limit) {
   546     assert(_implementors[i] == NULL, "should be exactly one implementor");
   547     oop_store_without_check((oop*)&_implementors[i], k);
   548   } else if (i == implementors_limit) {
   549     // clear out the list on first overflow
   550     for (int i2 = 0; i2 < implementors_limit; i2++)
   551       oop_store_without_check((oop*)&_implementors[i2], NULL);
   552   }
   554   // The implementor also implements the transitive_interfaces
   555   for (int index = 0; index < local_interfaces()->length(); index++) {
   556     instanceKlass::cast(klassOop(local_interfaces()->obj_at(index)))->add_implementor(k);
   557   }
   558 }
   560 void instanceKlass::init_implementor() {
   561   for (int i = 0; i < implementors_limit; i++)
   562     oop_store_without_check((oop*)&_implementors[i], NULL);
   563   _nof_implementors = 0;
   564 }
   567 void instanceKlass::process_interfaces(Thread *thread) {
   568   // link this class into the implementors list of every interface it implements
   569   KlassHandle this_as_oop (thread, this->as_klassOop());
   570   for (int i = local_interfaces()->length() - 1; i >= 0; i--) {
   571     assert(local_interfaces()->obj_at(i)->is_klass(), "must be a klass");
   572     instanceKlass* interf = instanceKlass::cast(klassOop(local_interfaces()->obj_at(i)));
   573     assert(interf->is_interface(), "expected interface");
   574     interf->add_implementor(this_as_oop());
   575   }
   576 }
   578 bool instanceKlass::can_be_primary_super_slow() const {
   579   if (is_interface())
   580     return false;
   581   else
   582     return Klass::can_be_primary_super_slow();
   583 }
   585 objArrayOop instanceKlass::compute_secondary_supers(int num_extra_slots, TRAPS) {
   586   // The secondaries are the implemented interfaces.
   587   instanceKlass* ik = instanceKlass::cast(as_klassOop());
   588   objArrayHandle interfaces (THREAD, ik->transitive_interfaces());
   589   int num_secondaries = num_extra_slots + interfaces->length();
   590   if (num_secondaries == 0) {
   591     return Universe::the_empty_system_obj_array();
   592   } else if (num_extra_slots == 0) {
   593     return interfaces();
   594   } else {
   595     // a mix of both
   596     objArrayOop secondaries = oopFactory::new_system_objArray(num_secondaries, CHECK_NULL);
   597     for (int i = 0; i < interfaces->length(); i++) {
   598       secondaries->obj_at_put(num_extra_slots+i, interfaces->obj_at(i));
   599     }
   600     return secondaries;
   601   }
   602 }
   604 bool instanceKlass::compute_is_subtype_of(klassOop k) {
   605   if (Klass::cast(k)->is_interface()) {
   606     return implements_interface(k);
   607   } else {
   608     return Klass::compute_is_subtype_of(k);
   609   }
   610 }
   612 bool instanceKlass::implements_interface(klassOop k) const {
   613   if (as_klassOop() == k) return true;
   614   assert(Klass::cast(k)->is_interface(), "should be an interface class");
   615   for (int i = 0; i < transitive_interfaces()->length(); i++) {
   616     if (transitive_interfaces()->obj_at(i) == k) {
   617       return true;
   618     }
   619   }
   620   return false;
   621 }
   623 objArrayOop instanceKlass::allocate_objArray(int n, int length, TRAPS) {
   624   if (length < 0) THROW_0(vmSymbols::java_lang_NegativeArraySizeException());
   625   if (length > arrayOopDesc::max_array_length(T_OBJECT)) {
   626     report_java_out_of_memory("Requested array size exceeds VM limit");
   627     THROW_OOP_0(Universe::out_of_memory_error_array_size());
   628   }
   629   int size = objArrayOopDesc::object_size(length);
   630   klassOop ak = array_klass(n, CHECK_NULL);
   631   KlassHandle h_ak (THREAD, ak);
   632   objArrayOop o =
   633     (objArrayOop)CollectedHeap::array_allocate(h_ak, size, length, CHECK_NULL);
   634   return o;
   635 }
   637 instanceOop instanceKlass::register_finalizer(instanceOop i, TRAPS) {
   638   if (TraceFinalizerRegistration) {
   639     tty->print("Registered ");
   640     i->print_value_on(tty);
   641     tty->print_cr(" (" INTPTR_FORMAT ") as finalizable", (address)i);
   642   }
   643   instanceHandle h_i(THREAD, i);
   644   // Pass the handle as argument, JavaCalls::call expects oop as jobjects
   645   JavaValue result(T_VOID);
   646   JavaCallArguments args(h_i);
   647   methodHandle mh (THREAD, Universe::finalizer_register_method());
   648   JavaCalls::call(&result, mh, &args, CHECK_NULL);
   649   return h_i();
   650 }
   652 instanceOop instanceKlass::allocate_instance(TRAPS) {
   653   assert(!oop_is_instanceMirror(), "wrong allocation path");
   654   bool has_finalizer_flag = has_finalizer(); // Query before possible GC
   655   int size = size_helper();  // Query before forming handle.
   657   KlassHandle h_k(THREAD, as_klassOop());
   659   instanceOop i;
   661   i = (instanceOop)CollectedHeap::obj_allocate(h_k, size, CHECK_NULL);
   662   if (has_finalizer_flag && !RegisterFinalizersAtInit) {
   663     i = register_finalizer(i, CHECK_NULL);
   664   }
   665   return i;
   666 }
   668 instanceOop instanceKlass::allocate_permanent_instance(TRAPS) {
   669   // Finalizer registration occurs in the Object.<init> constructor
   670   // and constructors normally aren't run when allocating perm
   671   // instances so simply disallow finalizable perm objects.  This can
   672   // be relaxed if a need for it is found.
   673   assert(!has_finalizer(), "perm objects not allowed to have finalizers");
   674   assert(!oop_is_instanceMirror(), "wrong allocation path");
   675   int size = size_helper();  // Query before forming handle.
   676   KlassHandle h_k(THREAD, as_klassOop());
   677   instanceOop i = (instanceOop)
   678     CollectedHeap::permanent_obj_allocate(h_k, size, CHECK_NULL);
   679   return i;
   680 }
   682 void instanceKlass::check_valid_for_instantiation(bool throwError, TRAPS) {
   683   if (is_interface() || is_abstract()) {
   684     ResourceMark rm(THREAD);
   685     THROW_MSG(throwError ? vmSymbols::java_lang_InstantiationError()
   686               : vmSymbols::java_lang_InstantiationException(), external_name());
   687   }
   688   if (as_klassOop() == SystemDictionary::Class_klass()) {
   689     ResourceMark rm(THREAD);
   690     THROW_MSG(throwError ? vmSymbols::java_lang_IllegalAccessError()
   691               : vmSymbols::java_lang_IllegalAccessException(), external_name());
   692   }
   693 }
   695 klassOop instanceKlass::array_klass_impl(bool or_null, int n, TRAPS) {
   696   instanceKlassHandle this_oop(THREAD, as_klassOop());
   697   return array_klass_impl(this_oop, or_null, n, THREAD);
   698 }
   700 klassOop instanceKlass::array_klass_impl(instanceKlassHandle this_oop, bool or_null, int n, TRAPS) {
   701   if (this_oop->array_klasses() == NULL) {
   702     if (or_null) return NULL;
   704     ResourceMark rm;
   705     JavaThread *jt = (JavaThread *)THREAD;
   706     {
   707       // Atomic creation of array_klasses
   708       MutexLocker mc(Compile_lock, THREAD);   // for vtables
   709       MutexLocker ma(MultiArray_lock, THREAD);
   711       // Check if update has already taken place
   712       if (this_oop->array_klasses() == NULL) {
   713         objArrayKlassKlass* oakk =
   714           (objArrayKlassKlass*)Universe::objArrayKlassKlassObj()->klass_part();
   716         klassOop  k = oakk->allocate_objArray_klass(1, this_oop, CHECK_NULL);
   717         this_oop->set_array_klasses(k);
   718       }
   719     }
   720   }
   721   // _this will always be set at this point
   722   objArrayKlass* oak = (objArrayKlass*)this_oop->array_klasses()->klass_part();
   723   if (or_null) {
   724     return oak->array_klass_or_null(n);
   725   }
   726   return oak->array_klass(n, CHECK_NULL);
   727 }
   729 klassOop instanceKlass::array_klass_impl(bool or_null, TRAPS) {
   730   return array_klass_impl(or_null, 1, THREAD);
   731 }
   733 void instanceKlass::call_class_initializer(TRAPS) {
   734   instanceKlassHandle ik (THREAD, as_klassOop());
   735   call_class_initializer_impl(ik, THREAD);
   736 }
   738 static int call_class_initializer_impl_counter = 0;   // for debugging
   740 methodOop instanceKlass::class_initializer() {
   741   methodOop clinit = find_method(
   742       vmSymbols::class_initializer_name(), vmSymbols::void_method_signature());
   743   if (clinit != NULL && clinit->has_valid_initializer_flags()) {
   744     return clinit;
   745   }
   746   return NULL;
   747 }
   749 void instanceKlass::call_class_initializer_impl(instanceKlassHandle this_oop, TRAPS) {
   750   methodHandle h_method(THREAD, this_oop->class_initializer());
   751   assert(!this_oop->is_initialized(), "we cannot initialize twice");
   752   if (TraceClassInitialization) {
   753     tty->print("%d Initializing ", call_class_initializer_impl_counter++);
   754     this_oop->name()->print_value();
   755     tty->print_cr("%s (" INTPTR_FORMAT ")", h_method() == NULL ? "(no method)" : "", (address)this_oop());
   756   }
   757   if (h_method() != NULL) {
   758     JavaCallArguments args; // No arguments
   759     JavaValue result(T_VOID);
   760     JavaCalls::call(&result, h_method, &args, CHECK); // Static call (no args)
   761   }
   762 }
   765 void instanceKlass::mask_for(methodHandle method, int bci,
   766   InterpreterOopMap* entry_for) {
   767   // Dirty read, then double-check under a lock.
   768   if (_oop_map_cache == NULL) {
   769     // Otherwise, allocate a new one.
   770     MutexLocker x(OopMapCacheAlloc_lock);
   771     // First time use. Allocate a cache in C heap
   772     if (_oop_map_cache == NULL) {
   773       _oop_map_cache = new OopMapCache();
   774     }
   775   }
   776   // _oop_map_cache is constant after init; lookup below does is own locking.
   777   _oop_map_cache->lookup(method, bci, entry_for);
   778 }
   781 bool instanceKlass::find_local_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
   782   const int n = fields()->length();
   783   for (int i = 0; i < n; i += next_offset ) {
   784     int name_index = fields()->ushort_at(i + name_index_offset);
   785     int sig_index  = fields()->ushort_at(i + signature_index_offset);
   786     Symbol* f_name = constants()->symbol_at(name_index);
   787     Symbol* f_sig  = constants()->symbol_at(sig_index);
   788     if (f_name == name && f_sig == sig) {
   789       fd->initialize(as_klassOop(), i);
   790       return true;
   791     }
   792   }
   793   return false;
   794 }
   797 void instanceKlass::shared_symbols_iterate(SymbolClosure* closure) {
   798   Klass::shared_symbols_iterate(closure);
   799   closure->do_symbol(&_generic_signature);
   800   closure->do_symbol(&_source_file_name);
   801   closure->do_symbol(&_source_debug_extension);
   803   const int n = fields()->length();
   804   for (int i = 0; i < n; i += next_offset ) {
   805     int name_index = fields()->ushort_at(i + name_index_offset);
   806     closure->do_symbol(constants()->symbol_at_addr(name_index));
   807     int sig_index  = fields()->ushort_at(i + signature_index_offset);
   808     closure->do_symbol(constants()->symbol_at_addr(sig_index));
   809   }
   810 }
   813 klassOop instanceKlass::find_interface_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
   814   const int n = local_interfaces()->length();
   815   for (int i = 0; i < n; i++) {
   816     klassOop intf1 = klassOop(local_interfaces()->obj_at(i));
   817     assert(Klass::cast(intf1)->is_interface(), "just checking type");
   818     // search for field in current interface
   819     if (instanceKlass::cast(intf1)->find_local_field(name, sig, fd)) {
   820       assert(fd->is_static(), "interface field must be static");
   821       return intf1;
   822     }
   823     // search for field in direct superinterfaces
   824     klassOop intf2 = instanceKlass::cast(intf1)->find_interface_field(name, sig, fd);
   825     if (intf2 != NULL) return intf2;
   826   }
   827   // otherwise field lookup fails
   828   return NULL;
   829 }
   832 klassOop instanceKlass::find_field(Symbol* name, Symbol* sig, fieldDescriptor* fd) const {
   833   // search order according to newest JVM spec (5.4.3.2, p.167).
   834   // 1) search for field in current klass
   835   if (find_local_field(name, sig, fd)) {
   836     return as_klassOop();
   837   }
   838   // 2) search for field recursively in direct superinterfaces
   839   { klassOop intf = find_interface_field(name, sig, fd);
   840     if (intf != NULL) return intf;
   841   }
   842   // 3) apply field lookup recursively if superclass exists
   843   { klassOop supr = super();
   844     if (supr != NULL) return instanceKlass::cast(supr)->find_field(name, sig, fd);
   845   }
   846   // 4) otherwise field lookup fails
   847   return NULL;
   848 }
   851 klassOop instanceKlass::find_field(Symbol* name, Symbol* sig, bool is_static, fieldDescriptor* fd) const {
   852   // search order according to newest JVM spec (5.4.3.2, p.167).
   853   // 1) search for field in current klass
   854   if (find_local_field(name, sig, fd)) {
   855     if (fd->is_static() == is_static) return as_klassOop();
   856   }
   857   // 2) search for field recursively in direct superinterfaces
   858   if (is_static) {
   859     klassOop intf = find_interface_field(name, sig, fd);
   860     if (intf != NULL) return intf;
   861   }
   862   // 3) apply field lookup recursively if superclass exists
   863   { klassOop supr = super();
   864     if (supr != NULL) return instanceKlass::cast(supr)->find_field(name, sig, is_static, fd);
   865   }
   866   // 4) otherwise field lookup fails
   867   return NULL;
   868 }
   871 bool instanceKlass::find_local_field_from_offset(int offset, bool is_static, fieldDescriptor* fd) const {
   872   int length = fields()->length();
   873   for (int i = 0; i < length; i += next_offset) {
   874     if (offset_from_fields( i ) == offset) {
   875       fd->initialize(as_klassOop(), i);
   876       if (fd->is_static() == is_static) return true;
   877     }
   878   }
   879   return false;
   880 }
   883 bool instanceKlass::find_field_from_offset(int offset, bool is_static, fieldDescriptor* fd) const {
   884   klassOop klass = as_klassOop();
   885   while (klass != NULL) {
   886     if (instanceKlass::cast(klass)->find_local_field_from_offset(offset, is_static, fd)) {
   887       return true;
   888     }
   889     klass = Klass::cast(klass)->super();
   890   }
   891   return false;
   892 }
   895 void instanceKlass::methods_do(void f(methodOop method)) {
   896   int len = methods()->length();
   897   for (int index = 0; index < len; index++) {
   898     methodOop m = methodOop(methods()->obj_at(index));
   899     assert(m->is_method(), "must be method");
   900     f(m);
   901   }
   902 }
   905 void instanceKlass::do_local_static_fields(FieldClosure* cl) {
   906   fieldDescriptor fd;
   907   int length = fields()->length();
   908   for (int i = 0; i < length; i += next_offset) {
   909     fd.initialize(as_klassOop(), i);
   910     if (fd.is_static()) cl->do_field(&fd);
   911   }
   912 }
   915 void instanceKlass::do_local_static_fields(void f(fieldDescriptor*, TRAPS), TRAPS) {
   916   instanceKlassHandle h_this(THREAD, as_klassOop());
   917   do_local_static_fields_impl(h_this, f, CHECK);
   918 }
   921 void instanceKlass::do_local_static_fields_impl(instanceKlassHandle this_oop, void f(fieldDescriptor* fd, TRAPS), TRAPS) {
   922   fieldDescriptor fd;
   923   int length = this_oop->fields()->length();
   924   for (int i = 0; i < length; i += next_offset) {
   925     fd.initialize(this_oop(), i);
   926     if (fd.is_static()) { f(&fd, CHECK); } // Do NOT remove {}! (CHECK macro expands into several statements)
   927   }
   928 }
   931 static int compare_fields_by_offset(int* a, int* b) {
   932   return a[0] - b[0];
   933 }
   935 void instanceKlass::do_nonstatic_fields(FieldClosure* cl) {
   936   instanceKlass* super = superklass();
   937   if (super != NULL) {
   938     super->do_nonstatic_fields(cl);
   939   }
   940   fieldDescriptor fd;
   941   int length = fields()->length();
   942   // In DebugInfo nonstatic fields are sorted by offset.
   943   int* fields_sorted = NEW_C_HEAP_ARRAY(int, 2*(length+1));
   944   int j = 0;
   945   for (int i = 0; i < length; i += next_offset) {
   946     fd.initialize(as_klassOop(), i);
   947     if (!fd.is_static()) {
   948       fields_sorted[j + 0] = fd.offset();
   949       fields_sorted[j + 1] = i;
   950       j += 2;
   951     }
   952   }
   953   if (j > 0) {
   954     length = j;
   955     // _sort_Fn is defined in growableArray.hpp.
   956     qsort(fields_sorted, length/2, 2*sizeof(int), (_sort_Fn)compare_fields_by_offset);
   957     for (int i = 0; i < length; i += 2) {
   958       fd.initialize(as_klassOop(), fields_sorted[i + 1]);
   959       assert(!fd.is_static() && fd.offset() == fields_sorted[i], "only nonstatic fields");
   960       cl->do_field(&fd);
   961     }
   962   }
   963   FREE_C_HEAP_ARRAY(int, fields_sorted);
   964 }
   967 void instanceKlass::array_klasses_do(void f(klassOop k)) {
   968   if (array_klasses() != NULL)
   969     arrayKlass::cast(array_klasses())->array_klasses_do(f);
   970 }
   973 void instanceKlass::with_array_klasses_do(void f(klassOop k)) {
   974   f(as_klassOop());
   975   array_klasses_do(f);
   976 }
   978 #ifdef ASSERT
   979 static int linear_search(objArrayOop methods, Symbol* name, Symbol* signature) {
   980   int len = methods->length();
   981   for (int index = 0; index < len; index++) {
   982     methodOop m = (methodOop)(methods->obj_at(index));
   983     assert(m->is_method(), "must be method");
   984     if (m->signature() == signature && m->name() == name) {
   985        return index;
   986     }
   987   }
   988   return -1;
   989 }
   990 #endif
   992 methodOop instanceKlass::find_method(Symbol* name, Symbol* signature) const {
   993   return instanceKlass::find_method(methods(), name, signature);
   994 }
   996 methodOop instanceKlass::find_method(objArrayOop methods, Symbol* name, Symbol* signature) {
   997   int len = methods->length();
   998   // methods are sorted, so do binary search
   999   int l = 0;
  1000   int h = len - 1;
  1001   while (l <= h) {
  1002     int mid = (l + h) >> 1;
  1003     methodOop m = (methodOop)methods->obj_at(mid);
  1004     assert(m->is_method(), "must be method");
  1005     int res = m->name()->fast_compare(name);
  1006     if (res == 0) {
  1007       // found matching name; do linear search to find matching signature
  1008       // first, quick check for common case
  1009       if (m->signature() == signature) return m;
  1010       // search downwards through overloaded methods
  1011       int i;
  1012       for (i = mid - 1; i >= l; i--) {
  1013         methodOop m = (methodOop)methods->obj_at(i);
  1014         assert(m->is_method(), "must be method");
  1015         if (m->name() != name) break;
  1016         if (m->signature() == signature) return m;
  1018       // search upwards
  1019       for (i = mid + 1; i <= h; i++) {
  1020         methodOop m = (methodOop)methods->obj_at(i);
  1021         assert(m->is_method(), "must be method");
  1022         if (m->name() != name) break;
  1023         if (m->signature() == signature) return m;
  1025       // not found
  1026 #ifdef ASSERT
  1027       int index = linear_search(methods, name, signature);
  1028       assert(index == -1, err_msg("binary search should have found entry %d", index));
  1029 #endif
  1030       return NULL;
  1031     } else if (res < 0) {
  1032       l = mid + 1;
  1033     } else {
  1034       h = mid - 1;
  1037 #ifdef ASSERT
  1038   int index = linear_search(methods, name, signature);
  1039   assert(index == -1, err_msg("binary search should have found entry %d", index));
  1040 #endif
  1041   return NULL;
  1044 methodOop instanceKlass::uncached_lookup_method(Symbol* name, Symbol* signature) const {
  1045   klassOop klass = as_klassOop();
  1046   while (klass != NULL) {
  1047     methodOop method = instanceKlass::cast(klass)->find_method(name, signature);
  1048     if (method != NULL) return method;
  1049     klass = instanceKlass::cast(klass)->super();
  1051   return NULL;
  1054 // lookup a method in all the interfaces that this class implements
  1055 methodOop instanceKlass::lookup_method_in_all_interfaces(Symbol* name,
  1056                                                          Symbol* signature) const {
  1057   objArrayOop all_ifs = instanceKlass::cast(as_klassOop())->transitive_interfaces();
  1058   int num_ifs = all_ifs->length();
  1059   instanceKlass *ik = NULL;
  1060   for (int i = 0; i < num_ifs; i++) {
  1061     ik = instanceKlass::cast(klassOop(all_ifs->obj_at(i)));
  1062     methodOop m = ik->lookup_method(name, signature);
  1063     if (m != NULL) {
  1064       return m;
  1067   return NULL;
  1070 /* jni_id_for_impl for jfieldIds only */
  1071 JNIid* instanceKlass::jni_id_for_impl(instanceKlassHandle this_oop, int offset) {
  1072   MutexLocker ml(JfieldIdCreation_lock);
  1073   // Retry lookup after we got the lock
  1074   JNIid* probe = this_oop->jni_ids() == NULL ? NULL : this_oop->jni_ids()->find(offset);
  1075   if (probe == NULL) {
  1076     // Slow case, allocate new static field identifier
  1077     probe = new JNIid(this_oop->as_klassOop(), offset, this_oop->jni_ids());
  1078     this_oop->set_jni_ids(probe);
  1080   return probe;
  1084 /* jni_id_for for jfieldIds only */
  1085 JNIid* instanceKlass::jni_id_for(int offset) {
  1086   JNIid* probe = jni_ids() == NULL ? NULL : jni_ids()->find(offset);
  1087   if (probe == NULL) {
  1088     probe = jni_id_for_impl(this->as_klassOop(), offset);
  1090   return probe;
  1094 // Lookup or create a jmethodID.
  1095 // This code is called by the VMThread and JavaThreads so the
  1096 // locking has to be done very carefully to avoid deadlocks
  1097 // and/or other cache consistency problems.
  1098 //
  1099 jmethodID instanceKlass::get_jmethod_id(instanceKlassHandle ik_h, methodHandle method_h) {
  1100   size_t idnum = (size_t)method_h->method_idnum();
  1101   jmethodID* jmeths = ik_h->methods_jmethod_ids_acquire();
  1102   size_t length = 0;
  1103   jmethodID id = NULL;
  1105   // We use a double-check locking idiom here because this cache is
  1106   // performance sensitive. In the normal system, this cache only
  1107   // transitions from NULL to non-NULL which is safe because we use
  1108   // release_set_methods_jmethod_ids() to advertise the new cache.
  1109   // A partially constructed cache should never be seen by a racing
  1110   // thread. We also use release_store_ptr() to save a new jmethodID
  1111   // in the cache so a partially constructed jmethodID should never be
  1112   // seen either. Cache reads of existing jmethodIDs proceed without a
  1113   // lock, but cache writes of a new jmethodID requires uniqueness and
  1114   // creation of the cache itself requires no leaks so a lock is
  1115   // generally acquired in those two cases.
  1116   //
  1117   // If the RedefineClasses() API has been used, then this cache can
  1118   // grow and we'll have transitions from non-NULL to bigger non-NULL.
  1119   // Cache creation requires no leaks and we require safety between all
  1120   // cache accesses and freeing of the old cache so a lock is generally
  1121   // acquired when the RedefineClasses() API has been used.
  1123   if (jmeths != NULL) {
  1124     // the cache already exists
  1125     if (!ik_h->idnum_can_increment()) {
  1126       // the cache can't grow so we can just get the current values
  1127       get_jmethod_id_length_value(jmeths, idnum, &length, &id);
  1128     } else {
  1129       // cache can grow so we have to be more careful
  1130       if (Threads::number_of_threads() == 0 ||
  1131           SafepointSynchronize::is_at_safepoint()) {
  1132         // we're single threaded or at a safepoint - no locking needed
  1133         get_jmethod_id_length_value(jmeths, idnum, &length, &id);
  1134       } else {
  1135         MutexLocker ml(JmethodIdCreation_lock);
  1136         get_jmethod_id_length_value(jmeths, idnum, &length, &id);
  1140   // implied else:
  1141   // we need to allocate a cache so default length and id values are good
  1143   if (jmeths == NULL ||   // no cache yet
  1144       length <= idnum ||  // cache is too short
  1145       id == NULL) {       // cache doesn't contain entry
  1147     // This function can be called by the VMThread so we have to do all
  1148     // things that might block on a safepoint before grabbing the lock.
  1149     // Otherwise, we can deadlock with the VMThread or have a cache
  1150     // consistency issue. These vars keep track of what we might have
  1151     // to free after the lock is dropped.
  1152     jmethodID  to_dealloc_id     = NULL;
  1153     jmethodID* to_dealloc_jmeths = NULL;
  1155     // may not allocate new_jmeths or use it if we allocate it
  1156     jmethodID* new_jmeths = NULL;
  1157     if (length <= idnum) {
  1158       // allocate a new cache that might be used
  1159       size_t size = MAX2(idnum+1, (size_t)ik_h->idnum_allocated_count());
  1160       new_jmeths = NEW_C_HEAP_ARRAY(jmethodID, size+1);
  1161       memset(new_jmeths, 0, (size+1)*sizeof(jmethodID));
  1162       // cache size is stored in element[0], other elements offset by one
  1163       new_jmeths[0] = (jmethodID)size;
  1166     // allocate a new jmethodID that might be used
  1167     jmethodID new_id = NULL;
  1168     if (method_h->is_old() && !method_h->is_obsolete()) {
  1169       // The method passed in is old (but not obsolete), we need to use the current version
  1170       methodOop current_method = ik_h->method_with_idnum((int)idnum);
  1171       assert(current_method != NULL, "old and but not obsolete, so should exist");
  1172       methodHandle current_method_h(current_method == NULL? method_h() : current_method);
  1173       new_id = JNIHandles::make_jmethod_id(current_method_h);
  1174     } else {
  1175       // It is the current version of the method or an obsolete method,
  1176       // use the version passed in
  1177       new_id = JNIHandles::make_jmethod_id(method_h);
  1180     if (Threads::number_of_threads() == 0 ||
  1181         SafepointSynchronize::is_at_safepoint()) {
  1182       // we're single threaded or at a safepoint - no locking needed
  1183       id = get_jmethod_id_fetch_or_update(ik_h, idnum, new_id, new_jmeths,
  1184                                           &to_dealloc_id, &to_dealloc_jmeths);
  1185     } else {
  1186       MutexLocker ml(JmethodIdCreation_lock);
  1187       id = get_jmethod_id_fetch_or_update(ik_h, idnum, new_id, new_jmeths,
  1188                                           &to_dealloc_id, &to_dealloc_jmeths);
  1191     // The lock has been dropped so we can free resources.
  1192     // Free up either the old cache or the new cache if we allocated one.
  1193     if (to_dealloc_jmeths != NULL) {
  1194       FreeHeap(to_dealloc_jmeths);
  1196     // free up the new ID since it wasn't needed
  1197     if (to_dealloc_id != NULL) {
  1198       JNIHandles::destroy_jmethod_id(to_dealloc_id);
  1201   return id;
  1205 // Common code to fetch the jmethodID from the cache or update the
  1206 // cache with the new jmethodID. This function should never do anything
  1207 // that causes the caller to go to a safepoint or we can deadlock with
  1208 // the VMThread or have cache consistency issues.
  1209 //
  1210 jmethodID instanceKlass::get_jmethod_id_fetch_or_update(
  1211             instanceKlassHandle ik_h, size_t idnum, jmethodID new_id,
  1212             jmethodID* new_jmeths, jmethodID* to_dealloc_id_p,
  1213             jmethodID** to_dealloc_jmeths_p) {
  1214   assert(new_id != NULL, "sanity check");
  1215   assert(to_dealloc_id_p != NULL, "sanity check");
  1216   assert(to_dealloc_jmeths_p != NULL, "sanity check");
  1217   assert(Threads::number_of_threads() == 0 ||
  1218          SafepointSynchronize::is_at_safepoint() ||
  1219          JmethodIdCreation_lock->owned_by_self(), "sanity check");
  1221   // reacquire the cache - we are locked, single threaded or at a safepoint
  1222   jmethodID* jmeths = ik_h->methods_jmethod_ids_acquire();
  1223   jmethodID  id     = NULL;
  1224   size_t     length = 0;
  1226   if (jmeths == NULL ||                         // no cache yet
  1227       (length = (size_t)jmeths[0]) <= idnum) {  // cache is too short
  1228     if (jmeths != NULL) {
  1229       // copy any existing entries from the old cache
  1230       for (size_t index = 0; index < length; index++) {
  1231         new_jmeths[index+1] = jmeths[index+1];
  1233       *to_dealloc_jmeths_p = jmeths;  // save old cache for later delete
  1235     ik_h->release_set_methods_jmethod_ids(jmeths = new_jmeths);
  1236   } else {
  1237     // fetch jmethodID (if any) from the existing cache
  1238     id = jmeths[idnum+1];
  1239     *to_dealloc_jmeths_p = new_jmeths;  // save new cache for later delete
  1241   if (id == NULL) {
  1242     // No matching jmethodID in the existing cache or we have a new
  1243     // cache or we just grew the cache. This cache write is done here
  1244     // by the first thread to win the foot race because a jmethodID
  1245     // needs to be unique once it is generally available.
  1246     id = new_id;
  1248     // The jmethodID cache can be read while unlocked so we have to
  1249     // make sure the new jmethodID is complete before installing it
  1250     // in the cache.
  1251     OrderAccess::release_store_ptr(&jmeths[idnum+1], id);
  1252   } else {
  1253     *to_dealloc_id_p = new_id; // save new id for later delete
  1255   return id;
  1259 // Common code to get the jmethodID cache length and the jmethodID
  1260 // value at index idnum if there is one.
  1261 //
  1262 void instanceKlass::get_jmethod_id_length_value(jmethodID* cache,
  1263        size_t idnum, size_t *length_p, jmethodID* id_p) {
  1264   assert(cache != NULL, "sanity check");
  1265   assert(length_p != NULL, "sanity check");
  1266   assert(id_p != NULL, "sanity check");
  1268   // cache size is stored in element[0], other elements offset by one
  1269   *length_p = (size_t)cache[0];
  1270   if (*length_p <= idnum) {  // cache is too short
  1271     *id_p = NULL;
  1272   } else {
  1273     *id_p = cache[idnum+1];  // fetch jmethodID (if any)
  1278 // Lookup a jmethodID, NULL if not found.  Do no blocking, no allocations, no handles
  1279 jmethodID instanceKlass::jmethod_id_or_null(methodOop method) {
  1280   size_t idnum = (size_t)method->method_idnum();
  1281   jmethodID* jmeths = methods_jmethod_ids_acquire();
  1282   size_t length;                                // length assigned as debugging crumb
  1283   jmethodID id = NULL;
  1284   if (jmeths != NULL &&                         // If there is a cache
  1285       (length = (size_t)jmeths[0]) > idnum) {   // and if it is long enough,
  1286     id = jmeths[idnum+1];                       // Look up the id (may be NULL)
  1288   return id;
  1292 // Cache an itable index
  1293 void instanceKlass::set_cached_itable_index(size_t idnum, int index) {
  1294   int* indices = methods_cached_itable_indices_acquire();
  1295   int* to_dealloc_indices = NULL;
  1297   // We use a double-check locking idiom here because this cache is
  1298   // performance sensitive. In the normal system, this cache only
  1299   // transitions from NULL to non-NULL which is safe because we use
  1300   // release_set_methods_cached_itable_indices() to advertise the
  1301   // new cache. A partially constructed cache should never be seen
  1302   // by a racing thread. Cache reads and writes proceed without a
  1303   // lock, but creation of the cache itself requires no leaks so a
  1304   // lock is generally acquired in that case.
  1305   //
  1306   // If the RedefineClasses() API has been used, then this cache can
  1307   // grow and we'll have transitions from non-NULL to bigger non-NULL.
  1308   // Cache creation requires no leaks and we require safety between all
  1309   // cache accesses and freeing of the old cache so a lock is generally
  1310   // acquired when the RedefineClasses() API has been used.
  1312   if (indices == NULL || idnum_can_increment()) {
  1313     // we need a cache or the cache can grow
  1314     MutexLocker ml(JNICachedItableIndex_lock);
  1315     // reacquire the cache to see if another thread already did the work
  1316     indices = methods_cached_itable_indices_acquire();
  1317     size_t length = 0;
  1318     // cache size is stored in element[0], other elements offset by one
  1319     if (indices == NULL || (length = (size_t)indices[0]) <= idnum) {
  1320       size_t size = MAX2(idnum+1, (size_t)idnum_allocated_count());
  1321       int* new_indices = NEW_C_HEAP_ARRAY(int, size+1);
  1322       new_indices[0] = (int)size;
  1323       // copy any existing entries
  1324       size_t i;
  1325       for (i = 0; i < length; i++) {
  1326         new_indices[i+1] = indices[i+1];
  1328       // Set all the rest to -1
  1329       for (i = length; i < size; i++) {
  1330         new_indices[i+1] = -1;
  1332       if (indices != NULL) {
  1333         // We have an old cache to delete so save it for after we
  1334         // drop the lock.
  1335         to_dealloc_indices = indices;
  1337       release_set_methods_cached_itable_indices(indices = new_indices);
  1340     if (idnum_can_increment()) {
  1341       // this cache can grow so we have to write to it safely
  1342       indices[idnum+1] = index;
  1344   } else {
  1345     CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
  1348   if (!idnum_can_increment()) {
  1349     // The cache cannot grow and this JNI itable index value does not
  1350     // have to be unique like a jmethodID. If there is a race to set it,
  1351     // it doesn't matter.
  1352     indices[idnum+1] = index;
  1355   if (to_dealloc_indices != NULL) {
  1356     // we allocated a new cache so free the old one
  1357     FreeHeap(to_dealloc_indices);
  1362 // Retrieve a cached itable index
  1363 int instanceKlass::cached_itable_index(size_t idnum) {
  1364   int* indices = methods_cached_itable_indices_acquire();
  1365   if (indices != NULL && ((size_t)indices[0]) > idnum) {
  1366      // indices exist and are long enough, retrieve possible cached
  1367     return indices[idnum+1];
  1369   return -1;
  1373 //
  1374 // nmethodBucket is used to record dependent nmethods for
  1375 // deoptimization.  nmethod dependencies are actually <klass, method>
  1376 // pairs but we really only care about the klass part for purposes of
  1377 // finding nmethods which might need to be deoptimized.  Instead of
  1378 // recording the method, a count of how many times a particular nmethod
  1379 // was recorded is kept.  This ensures that any recording errors are
  1380 // noticed since an nmethod should be removed as many times are it's
  1381 // added.
  1382 //
  1383 class nmethodBucket {
  1384  private:
  1385   nmethod*       _nmethod;
  1386   int            _count;
  1387   nmethodBucket* _next;
  1389  public:
  1390   nmethodBucket(nmethod* nmethod, nmethodBucket* next) {
  1391     _nmethod = nmethod;
  1392     _next = next;
  1393     _count = 1;
  1395   int count()                             { return _count; }
  1396   int increment()                         { _count += 1; return _count; }
  1397   int decrement()                         { _count -= 1; assert(_count >= 0, "don't underflow"); return _count; }
  1398   nmethodBucket* next()                   { return _next; }
  1399   void set_next(nmethodBucket* b)         { _next = b; }
  1400   nmethod* get_nmethod()                  { return _nmethod; }
  1401 };
  1404 //
  1405 // Walk the list of dependent nmethods searching for nmethods which
  1406 // are dependent on the klassOop that was passed in and mark them for
  1407 // deoptimization.  Returns the number of nmethods found.
  1408 //
  1409 int instanceKlass::mark_dependent_nmethods(DepChange& changes) {
  1410   assert_locked_or_safepoint(CodeCache_lock);
  1411   int found = 0;
  1412   nmethodBucket* b = _dependencies;
  1413   while (b != NULL) {
  1414     nmethod* nm = b->get_nmethod();
  1415     // since dependencies aren't removed until an nmethod becomes a zombie,
  1416     // the dependency list may contain nmethods which aren't alive.
  1417     if (nm->is_alive() && !nm->is_marked_for_deoptimization() && nm->check_dependency_on(changes)) {
  1418       if (TraceDependencies) {
  1419         ResourceMark rm;
  1420         tty->print_cr("Marked for deoptimization");
  1421         tty->print_cr("  context = %s", this->external_name());
  1422         changes.print();
  1423         nm->print();
  1424         nm->print_dependencies();
  1426       nm->mark_for_deoptimization();
  1427       found++;
  1429     b = b->next();
  1431   return found;
  1435 //
  1436 // Add an nmethodBucket to the list of dependencies for this nmethod.
  1437 // It's possible that an nmethod has multiple dependencies on this klass
  1438 // so a count is kept for each bucket to guarantee that creation and
  1439 // deletion of dependencies is consistent.
  1440 //
  1441 void instanceKlass::add_dependent_nmethod(nmethod* nm) {
  1442   assert_locked_or_safepoint(CodeCache_lock);
  1443   nmethodBucket* b = _dependencies;
  1444   nmethodBucket* last = NULL;
  1445   while (b != NULL) {
  1446     if (nm == b->get_nmethod()) {
  1447       b->increment();
  1448       return;
  1450     b = b->next();
  1452   _dependencies = new nmethodBucket(nm, _dependencies);
  1456 //
  1457 // Decrement count of the nmethod in the dependency list and remove
  1458 // the bucket competely when the count goes to 0.  This method must
  1459 // find a corresponding bucket otherwise there's a bug in the
  1460 // recording of dependecies.
  1461 //
  1462 void instanceKlass::remove_dependent_nmethod(nmethod* nm) {
  1463   assert_locked_or_safepoint(CodeCache_lock);
  1464   nmethodBucket* b = _dependencies;
  1465   nmethodBucket* last = NULL;
  1466   while (b != NULL) {
  1467     if (nm == b->get_nmethod()) {
  1468       if (b->decrement() == 0) {
  1469         if (last == NULL) {
  1470           _dependencies = b->next();
  1471         } else {
  1472           last->set_next(b->next());
  1474         delete b;
  1476       return;
  1478     last = b;
  1479     b = b->next();
  1481 #ifdef ASSERT
  1482   tty->print_cr("### %s can't find dependent nmethod:", this->external_name());
  1483   nm->print();
  1484 #endif // ASSERT
  1485   ShouldNotReachHere();
  1489 #ifndef PRODUCT
  1490 void instanceKlass::print_dependent_nmethods(bool verbose) {
  1491   nmethodBucket* b = _dependencies;
  1492   int idx = 0;
  1493   while (b != NULL) {
  1494     nmethod* nm = b->get_nmethod();
  1495     tty->print("[%d] count=%d { ", idx++, b->count());
  1496     if (!verbose) {
  1497       nm->print_on(tty, "nmethod");
  1498       tty->print_cr(" } ");
  1499     } else {
  1500       nm->print();
  1501       nm->print_dependencies();
  1502       tty->print_cr("--- } ");
  1504     b = b->next();
  1509 bool instanceKlass::is_dependent_nmethod(nmethod* nm) {
  1510   nmethodBucket* b = _dependencies;
  1511   while (b != NULL) {
  1512     if (nm == b->get_nmethod()) {
  1513       return true;
  1515     b = b->next();
  1517   return false;
  1519 #endif //PRODUCT
  1522 #ifdef ASSERT
  1523 template <class T> void assert_is_in(T *p) {
  1524   T heap_oop = oopDesc::load_heap_oop(p);
  1525   if (!oopDesc::is_null(heap_oop)) {
  1526     oop o = oopDesc::decode_heap_oop_not_null(heap_oop);
  1527     assert(Universe::heap()->is_in(o), "should be in heap");
  1530 template <class T> void assert_is_in_closed_subset(T *p) {
  1531   T heap_oop = oopDesc::load_heap_oop(p);
  1532   if (!oopDesc::is_null(heap_oop)) {
  1533     oop o = oopDesc::decode_heap_oop_not_null(heap_oop);
  1534     assert(Universe::heap()->is_in_closed_subset(o), "should be in closed");
  1537 template <class T> void assert_is_in_reserved(T *p) {
  1538   T heap_oop = oopDesc::load_heap_oop(p);
  1539   if (!oopDesc::is_null(heap_oop)) {
  1540     oop o = oopDesc::decode_heap_oop_not_null(heap_oop);
  1541     assert(Universe::heap()->is_in_reserved(o), "should be in reserved");
  1544 template <class T> void assert_nothing(T *p) {}
  1546 #else
  1547 template <class T> void assert_is_in(T *p) {}
  1548 template <class T> void assert_is_in_closed_subset(T *p) {}
  1549 template <class T> void assert_is_in_reserved(T *p) {}
  1550 template <class T> void assert_nothing(T *p) {}
  1551 #endif // ASSERT
  1553 //
  1554 // Macros that iterate over areas of oops which are specialized on type of
  1555 // oop pointer either narrow or wide, depending on UseCompressedOops
  1556 //
  1557 // Parameters are:
  1558 //   T         - type of oop to point to (either oop or narrowOop)
  1559 //   start_p   - starting pointer for region to iterate over
  1560 //   count     - number of oops or narrowOops to iterate over
  1561 //   do_oop    - action to perform on each oop (it's arbitrary C code which
  1562 //               makes it more efficient to put in a macro rather than making
  1563 //               it a template function)
  1564 //   assert_fn - assert function which is template function because performance
  1565 //               doesn't matter when enabled.
  1566 #define InstanceKlass_SPECIALIZED_OOP_ITERATE( \
  1567   T, start_p, count, do_oop,                \
  1568   assert_fn)                                \
  1569 {                                           \
  1570   T* p         = (T*)(start_p);             \
  1571   T* const end = p + (count);               \
  1572   while (p < end) {                         \
  1573     (assert_fn)(p);                         \
  1574     do_oop;                                 \
  1575     ++p;                                    \
  1576   }                                         \
  1579 #define InstanceKlass_SPECIALIZED_OOP_REVERSE_ITERATE( \
  1580   T, start_p, count, do_oop,                \
  1581   assert_fn)                                \
  1582 {                                           \
  1583   T* const start = (T*)(start_p);           \
  1584   T*       p     = start + (count);         \
  1585   while (start < p) {                       \
  1586     --p;                                    \
  1587     (assert_fn)(p);                         \
  1588     do_oop;                                 \
  1589   }                                         \
  1592 #define InstanceKlass_SPECIALIZED_BOUNDED_OOP_ITERATE( \
  1593   T, start_p, count, low, high,             \
  1594   do_oop, assert_fn)                        \
  1595 {                                           \
  1596   T* const l = (T*)(low);                   \
  1597   T* const h = (T*)(high);                  \
  1598   assert(mask_bits((intptr_t)l, sizeof(T)-1) == 0 && \
  1599          mask_bits((intptr_t)h, sizeof(T)-1) == 0,   \
  1600          "bounded region must be properly aligned"); \
  1601   T* p       = (T*)(start_p);               \
  1602   T* end     = p + (count);                 \
  1603   if (p < l) p = l;                         \
  1604   if (end > h) end = h;                     \
  1605   while (p < end) {                         \
  1606     (assert_fn)(p);                         \
  1607     do_oop;                                 \
  1608     ++p;                                    \
  1609   }                                         \
  1613 // The following macros call specialized macros, passing either oop or
  1614 // narrowOop as the specialization type.  These test the UseCompressedOops
  1615 // flag.
  1616 #define InstanceKlass_OOP_MAP_ITERATE(obj, do_oop, assert_fn)            \
  1617 {                                                                        \
  1618   /* Compute oopmap block range. The common case                         \
  1619      is nonstatic_oop_map_size == 1. */                                  \
  1620   OopMapBlock* map           = start_of_nonstatic_oop_maps();            \
  1621   OopMapBlock* const end_map = map + nonstatic_oop_map_count();          \
  1622   if (UseCompressedOops) {                                               \
  1623     while (map < end_map) {                                              \
  1624       InstanceKlass_SPECIALIZED_OOP_ITERATE(narrowOop,                   \
  1625         obj->obj_field_addr<narrowOop>(map->offset()), map->count(),     \
  1626         do_oop, assert_fn)                                               \
  1627       ++map;                                                             \
  1628     }                                                                    \
  1629   } else {                                                               \
  1630     while (map < end_map) {                                              \
  1631       InstanceKlass_SPECIALIZED_OOP_ITERATE(oop,                         \
  1632         obj->obj_field_addr<oop>(map->offset()), map->count(),           \
  1633         do_oop, assert_fn)                                               \
  1634       ++map;                                                             \
  1635     }                                                                    \
  1636   }                                                                      \
  1639 #define InstanceKlass_OOP_MAP_REVERSE_ITERATE(obj, do_oop, assert_fn)    \
  1640 {                                                                        \
  1641   OopMapBlock* const start_map = start_of_nonstatic_oop_maps();          \
  1642   OopMapBlock* map             = start_map + nonstatic_oop_map_count();  \
  1643   if (UseCompressedOops) {                                               \
  1644     while (start_map < map) {                                            \
  1645       --map;                                                             \
  1646       InstanceKlass_SPECIALIZED_OOP_REVERSE_ITERATE(narrowOop,           \
  1647         obj->obj_field_addr<narrowOop>(map->offset()), map->count(),     \
  1648         do_oop, assert_fn)                                               \
  1649     }                                                                    \
  1650   } else {                                                               \
  1651     while (start_map < map) {                                            \
  1652       --map;                                                             \
  1653       InstanceKlass_SPECIALIZED_OOP_REVERSE_ITERATE(oop,                 \
  1654         obj->obj_field_addr<oop>(map->offset()), map->count(),           \
  1655         do_oop, assert_fn)                                               \
  1656     }                                                                    \
  1657   }                                                                      \
  1660 #define InstanceKlass_BOUNDED_OOP_MAP_ITERATE(obj, low, high, do_oop,    \
  1661                                               assert_fn)                 \
  1662 {                                                                        \
  1663   /* Compute oopmap block range. The common case is                      \
  1664      nonstatic_oop_map_size == 1, so we accept the                       \
  1665      usually non-existent extra overhead of examining                    \
  1666      all the maps. */                                                    \
  1667   OopMapBlock* map           = start_of_nonstatic_oop_maps();            \
  1668   OopMapBlock* const end_map = map + nonstatic_oop_map_count();          \
  1669   if (UseCompressedOops) {                                               \
  1670     while (map < end_map) {                                              \
  1671       InstanceKlass_SPECIALIZED_BOUNDED_OOP_ITERATE(narrowOop,           \
  1672         obj->obj_field_addr<narrowOop>(map->offset()), map->count(),     \
  1673         low, high,                                                       \
  1674         do_oop, assert_fn)                                               \
  1675       ++map;                                                             \
  1676     }                                                                    \
  1677   } else {                                                               \
  1678     while (map < end_map) {                                              \
  1679       InstanceKlass_SPECIALIZED_BOUNDED_OOP_ITERATE(oop,                 \
  1680         obj->obj_field_addr<oop>(map->offset()), map->count(),           \
  1681         low, high,                                                       \
  1682         do_oop, assert_fn)                                               \
  1683       ++map;                                                             \
  1684     }                                                                    \
  1685   }                                                                      \
  1688 void instanceKlass::oop_follow_contents(oop obj) {
  1689   assert(obj != NULL, "can't follow the content of NULL object");
  1690   obj->follow_header();
  1691   InstanceKlass_OOP_MAP_ITERATE( \
  1692     obj, \
  1693     MarkSweep::mark_and_push(p), \
  1694     assert_is_in_closed_subset)
  1697 #ifndef SERIALGC
  1698 void instanceKlass::oop_follow_contents(ParCompactionManager* cm,
  1699                                         oop obj) {
  1700   assert(obj != NULL, "can't follow the content of NULL object");
  1701   obj->follow_header(cm);
  1702   InstanceKlass_OOP_MAP_ITERATE( \
  1703     obj, \
  1704     PSParallelCompact::mark_and_push(cm, p), \
  1705     assert_is_in)
  1707 #endif // SERIALGC
  1709 // closure's do_header() method dicates whether the given closure should be
  1710 // applied to the klass ptr in the object header.
  1712 #define InstanceKlass_OOP_OOP_ITERATE_DEFN(OopClosureType, nv_suffix)        \
  1714 int instanceKlass::oop_oop_iterate##nv_suffix(oop obj, OopClosureType* closure) { \
  1715   SpecializationStats::record_iterate_call##nv_suffix(SpecializationStats::ik);\
  1716   /* header */                                                          \
  1717   if (closure->do_header()) {                                           \
  1718     obj->oop_iterate_header(closure);                                   \
  1719   }                                                                     \
  1720   InstanceKlass_OOP_MAP_ITERATE(                                        \
  1721     obj,                                                                \
  1722     SpecializationStats::                                               \
  1723       record_do_oop_call##nv_suffix(SpecializationStats::ik);           \
  1724     (closure)->do_oop##nv_suffix(p),                                    \
  1725     assert_is_in_closed_subset)                                         \
  1726   return size_helper();                                                 \
  1729 #ifndef SERIALGC
  1730 #define InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DEFN(OopClosureType, nv_suffix) \
  1732 int instanceKlass::oop_oop_iterate_backwards##nv_suffix(oop obj,                \
  1733                                               OopClosureType* closure) {        \
  1734   SpecializationStats::record_iterate_call##nv_suffix(SpecializationStats::ik); \
  1735   /* header */                                                                  \
  1736   if (closure->do_header()) {                                                   \
  1737     obj->oop_iterate_header(closure);                                           \
  1738   }                                                                             \
  1739   /* instance variables */                                                      \
  1740   InstanceKlass_OOP_MAP_REVERSE_ITERATE(                                        \
  1741     obj,                                                                        \
  1742     SpecializationStats::record_do_oop_call##nv_suffix(SpecializationStats::ik);\
  1743     (closure)->do_oop##nv_suffix(p),                                            \
  1744     assert_is_in_closed_subset)                                                 \
  1745    return size_helper();                                                        \
  1747 #endif // !SERIALGC
  1749 #define InstanceKlass_OOP_OOP_ITERATE_DEFN_m(OopClosureType, nv_suffix) \
  1751 int instanceKlass::oop_oop_iterate##nv_suffix##_m(oop obj,              \
  1752                                                   OopClosureType* closure, \
  1753                                                   MemRegion mr) {          \
  1754   SpecializationStats::record_iterate_call##nv_suffix(SpecializationStats::ik);\
  1755   if (closure->do_header()) {                                            \
  1756     obj->oop_iterate_header(closure, mr);                                \
  1757   }                                                                      \
  1758   InstanceKlass_BOUNDED_OOP_MAP_ITERATE(                                 \
  1759     obj, mr.start(), mr.end(),                                           \
  1760     (closure)->do_oop##nv_suffix(p),                                     \
  1761     assert_is_in_closed_subset)                                          \
  1762   return size_helper();                                                  \
  1765 ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceKlass_OOP_OOP_ITERATE_DEFN)
  1766 ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceKlass_OOP_OOP_ITERATE_DEFN)
  1767 ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceKlass_OOP_OOP_ITERATE_DEFN_m)
  1768 ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceKlass_OOP_OOP_ITERATE_DEFN_m)
  1769 #ifndef SERIALGC
  1770 ALL_OOP_OOP_ITERATE_CLOSURES_1(InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DEFN)
  1771 ALL_OOP_OOP_ITERATE_CLOSURES_2(InstanceKlass_OOP_OOP_ITERATE_BACKWARDS_DEFN)
  1772 #endif // !SERIALGC
  1774 int instanceKlass::oop_adjust_pointers(oop obj) {
  1775   int size = size_helper();
  1776   InstanceKlass_OOP_MAP_ITERATE( \
  1777     obj, \
  1778     MarkSweep::adjust_pointer(p), \
  1779     assert_is_in)
  1780   obj->adjust_header();
  1781   return size;
  1784 #ifndef SERIALGC
  1785 void instanceKlass::oop_push_contents(PSPromotionManager* pm, oop obj) {
  1786   InstanceKlass_OOP_MAP_REVERSE_ITERATE( \
  1787     obj, \
  1788     if (PSScavenge::should_scavenge(p)) { \
  1789       pm->claim_or_forward_depth(p); \
  1790     }, \
  1791     assert_nothing )
  1794 int instanceKlass::oop_update_pointers(ParCompactionManager* cm, oop obj) {
  1795   InstanceKlass_OOP_MAP_ITERATE( \
  1796     obj, \
  1797     PSParallelCompact::adjust_pointer(p), \
  1798     assert_nothing)
  1799   return size_helper();
  1802 #endif // SERIALGC
  1804 // This klass is alive but the implementor link is not followed/updated.
  1805 // Subklass and sibling links are handled by Klass::follow_weak_klass_links
  1807 void instanceKlass::follow_weak_klass_links(
  1808   BoolObjectClosure* is_alive, OopClosure* keep_alive) {
  1809   assert(is_alive->do_object_b(as_klassOop()), "this oop should be live");
  1810   if (ClassUnloading) {
  1811     for (int i = 0; i < implementors_limit; i++) {
  1812       klassOop impl = _implementors[i];
  1813       if (impl == NULL)  break;  // no more in the list
  1814       if (!is_alive->do_object_b(impl)) {
  1815         // remove this guy from the list by overwriting him with the tail
  1816         int lasti = --_nof_implementors;
  1817         assert(lasti >= i && lasti < implementors_limit, "just checking");
  1818         _implementors[i] = _implementors[lasti];
  1819         _implementors[lasti] = NULL;
  1820         --i; // rerun the loop at this index
  1823   } else {
  1824     for (int i = 0; i < implementors_limit; i++) {
  1825       keep_alive->do_oop(&adr_implementors()[i]);
  1828   Klass::follow_weak_klass_links(is_alive, keep_alive);
  1831 void instanceKlass::remove_unshareable_info() {
  1832   Klass::remove_unshareable_info();
  1833   init_implementor();
  1836 static void clear_all_breakpoints(methodOop m) {
  1837   m->clear_all_breakpoints();
  1840 void instanceKlass::release_C_heap_structures() {
  1841   // Deallocate oop map cache
  1842   if (_oop_map_cache != NULL) {
  1843     delete _oop_map_cache;
  1844     _oop_map_cache = NULL;
  1847   // Deallocate JNI identifiers for jfieldIDs
  1848   JNIid::deallocate(jni_ids());
  1849   set_jni_ids(NULL);
  1851   jmethodID* jmeths = methods_jmethod_ids_acquire();
  1852   if (jmeths != (jmethodID*)NULL) {
  1853     release_set_methods_jmethod_ids(NULL);
  1854     FreeHeap(jmeths);
  1857   int* indices = methods_cached_itable_indices_acquire();
  1858   if (indices != (int*)NULL) {
  1859     release_set_methods_cached_itable_indices(NULL);
  1860     FreeHeap(indices);
  1863   // release dependencies
  1864   nmethodBucket* b = _dependencies;
  1865   _dependencies = NULL;
  1866   while (b != NULL) {
  1867     nmethodBucket* next = b->next();
  1868     delete b;
  1869     b = next;
  1872   // Deallocate breakpoint records
  1873   if (breakpoints() != 0x0) {
  1874     methods_do(clear_all_breakpoints);
  1875     assert(breakpoints() == 0x0, "should have cleared breakpoints");
  1878   // deallocate information about previous versions
  1879   if (_previous_versions != NULL) {
  1880     for (int i = _previous_versions->length() - 1; i >= 0; i--) {
  1881       PreviousVersionNode * pv_node = _previous_versions->at(i);
  1882       delete pv_node;
  1884     delete _previous_versions;
  1885     _previous_versions = NULL;
  1888   // deallocate the cached class file
  1889   if (_cached_class_file_bytes != NULL) {
  1890     os::free(_cached_class_file_bytes);
  1891     _cached_class_file_bytes = NULL;
  1892     _cached_class_file_len = 0;
  1895   // Decrement symbol reference counts associated with the unloaded class.
  1896   if (_name != NULL) _name->decrement_refcount();
  1897   // unreference array name derived from this class name (arrays of an unloaded
  1898   // class can't be referenced anymore).
  1899   if (_array_name != NULL)  _array_name->decrement_refcount();
  1900   if (_source_file_name != NULL) _source_file_name->decrement_refcount();
  1901   if (_source_debug_extension != NULL) _source_debug_extension->decrement_refcount();
  1902   // walk constant pool and decrement symbol reference counts
  1903   _constants->unreference_symbols();
  1906 void instanceKlass::set_source_file_name(Symbol* n) {
  1907   _source_file_name = n;
  1908   if (_source_file_name != NULL) _source_file_name->increment_refcount();
  1911 void instanceKlass::set_source_debug_extension(Symbol* n) {
  1912   _source_debug_extension = n;
  1913   if (_source_debug_extension != NULL) _source_debug_extension->increment_refcount();
  1916 address instanceKlass::static_field_addr(int offset) {
  1917   return (address)(offset + instanceMirrorKlass::offset_of_static_fields() + (intptr_t)java_mirror());
  1921 const char* instanceKlass::signature_name() const {
  1922   const char* src = (const char*) (name()->as_C_string());
  1923   const int src_length = (int)strlen(src);
  1924   char* dest = NEW_RESOURCE_ARRAY(char, src_length + 3);
  1925   int src_index = 0;
  1926   int dest_index = 0;
  1927   dest[dest_index++] = 'L';
  1928   while (src_index < src_length) {
  1929     dest[dest_index++] = src[src_index++];
  1931   dest[dest_index++] = ';';
  1932   dest[dest_index] = '\0';
  1933   return dest;
  1936 // different verisons of is_same_class_package
  1937 bool instanceKlass::is_same_class_package(klassOop class2) {
  1938   klassOop class1 = as_klassOop();
  1939   oop classloader1 = instanceKlass::cast(class1)->class_loader();
  1940   Symbol* classname1 = Klass::cast(class1)->name();
  1942   if (Klass::cast(class2)->oop_is_objArray()) {
  1943     class2 = objArrayKlass::cast(class2)->bottom_klass();
  1945   oop classloader2;
  1946   if (Klass::cast(class2)->oop_is_instance()) {
  1947     classloader2 = instanceKlass::cast(class2)->class_loader();
  1948   } else {
  1949     assert(Klass::cast(class2)->oop_is_typeArray(), "should be type array");
  1950     classloader2 = NULL;
  1952   Symbol* classname2 = Klass::cast(class2)->name();
  1954   return instanceKlass::is_same_class_package(classloader1, classname1,
  1955                                               classloader2, classname2);
  1958 bool instanceKlass::is_same_class_package(oop classloader2, Symbol* classname2) {
  1959   klassOop class1 = as_klassOop();
  1960   oop classloader1 = instanceKlass::cast(class1)->class_loader();
  1961   Symbol* classname1 = Klass::cast(class1)->name();
  1963   return instanceKlass::is_same_class_package(classloader1, classname1,
  1964                                               classloader2, classname2);
  1967 // return true if two classes are in the same package, classloader
  1968 // and classname information is enough to determine a class's package
  1969 bool instanceKlass::is_same_class_package(oop class_loader1, Symbol* class_name1,
  1970                                           oop class_loader2, Symbol* class_name2) {
  1971   if (class_loader1 != class_loader2) {
  1972     return false;
  1973   } else if (class_name1 == class_name2) {
  1974     return true;                // skip painful bytewise comparison
  1975   } else {
  1976     ResourceMark rm;
  1978     // The Symbol*'s are in UTF8 encoding. Since we only need to check explicitly
  1979     // for ASCII characters ('/', 'L', '['), we can keep them in UTF8 encoding.
  1980     // Otherwise, we just compare jbyte values between the strings.
  1981     const jbyte *name1 = class_name1->base();
  1982     const jbyte *name2 = class_name2->base();
  1984     const jbyte *last_slash1 = UTF8::strrchr(name1, class_name1->utf8_length(), '/');
  1985     const jbyte *last_slash2 = UTF8::strrchr(name2, class_name2->utf8_length(), '/');
  1987     if ((last_slash1 == NULL) || (last_slash2 == NULL)) {
  1988       // One of the two doesn't have a package.  Only return true
  1989       // if the other one also doesn't have a package.
  1990       return last_slash1 == last_slash2;
  1991     } else {
  1992       // Skip over '['s
  1993       if (*name1 == '[') {
  1994         do {
  1995           name1++;
  1996         } while (*name1 == '[');
  1997         if (*name1 != 'L') {
  1998           // Something is terribly wrong.  Shouldn't be here.
  1999           return false;
  2002       if (*name2 == '[') {
  2003         do {
  2004           name2++;
  2005         } while (*name2 == '[');
  2006         if (*name2 != 'L') {
  2007           // Something is terribly wrong.  Shouldn't be here.
  2008           return false;
  2012       // Check that package part is identical
  2013       int length1 = last_slash1 - name1;
  2014       int length2 = last_slash2 - name2;
  2016       return UTF8::equal(name1, length1, name2, length2);
  2021 // Returns true iff super_method can be overridden by a method in targetclassname
  2022 // See JSL 3rd edition 8.4.6.1
  2023 // Assumes name-signature match
  2024 // "this" is instanceKlass of super_method which must exist
  2025 // note that the instanceKlass of the method in the targetclassname has not always been created yet
  2026 bool instanceKlass::is_override(methodHandle super_method, Handle targetclassloader, Symbol* targetclassname, TRAPS) {
  2027    // Private methods can not be overridden
  2028    if (super_method->is_private()) {
  2029      return false;
  2031    // If super method is accessible, then override
  2032    if ((super_method->is_protected()) ||
  2033        (super_method->is_public())) {
  2034      return true;
  2036    // Package-private methods are not inherited outside of package
  2037    assert(super_method->is_package_private(), "must be package private");
  2038    return(is_same_class_package(targetclassloader(), targetclassname));
  2041 /* defined for now in jvm.cpp, for historical reasons *--
  2042 klassOop instanceKlass::compute_enclosing_class_impl(instanceKlassHandle self,
  2043                                                      Symbol*& simple_name_result, TRAPS) {
  2044   ...
  2046 */
  2048 // tell if two classes have the same enclosing class (at package level)
  2049 bool instanceKlass::is_same_package_member_impl(instanceKlassHandle class1,
  2050                                                 klassOop class2_oop, TRAPS) {
  2051   if (class2_oop == class1->as_klassOop())          return true;
  2052   if (!Klass::cast(class2_oop)->oop_is_instance())  return false;
  2053   instanceKlassHandle class2(THREAD, class2_oop);
  2055   // must be in same package before we try anything else
  2056   if (!class1->is_same_class_package(class2->class_loader(), class2->name()))
  2057     return false;
  2059   // As long as there is an outer1.getEnclosingClass,
  2060   // shift the search outward.
  2061   instanceKlassHandle outer1 = class1;
  2062   for (;;) {
  2063     // As we walk along, look for equalities between outer1 and class2.
  2064     // Eventually, the walks will terminate as outer1 stops
  2065     // at the top-level class around the original class.
  2066     bool ignore_inner_is_member;
  2067     klassOop next = outer1->compute_enclosing_class(&ignore_inner_is_member,
  2068                                                     CHECK_false);
  2069     if (next == NULL)  break;
  2070     if (next == class2())  return true;
  2071     outer1 = instanceKlassHandle(THREAD, next);
  2074   // Now do the same for class2.
  2075   instanceKlassHandle outer2 = class2;
  2076   for (;;) {
  2077     bool ignore_inner_is_member;
  2078     klassOop next = outer2->compute_enclosing_class(&ignore_inner_is_member,
  2079                                                     CHECK_false);
  2080     if (next == NULL)  break;
  2081     // Might as well check the new outer against all available values.
  2082     if (next == class1())  return true;
  2083     if (next == outer1())  return true;
  2084     outer2 = instanceKlassHandle(THREAD, next);
  2087   // If by this point we have not found an equality between the
  2088   // two classes, we know they are in separate package members.
  2089   return false;
  2093 jint instanceKlass::compute_modifier_flags(TRAPS) const {
  2094   klassOop k = as_klassOop();
  2095   jint access = access_flags().as_int();
  2097   // But check if it happens to be member class.
  2098   typeArrayOop inner_class_list = inner_classes();
  2099   int length = (inner_class_list == NULL) ? 0 : inner_class_list->length();
  2100   assert (length % instanceKlass::inner_class_next_offset == 0, "just checking");
  2101   if (length > 0) {
  2102     typeArrayHandle inner_class_list_h(THREAD, inner_class_list);
  2103     instanceKlassHandle ik(THREAD, k);
  2104     for (int i = 0; i < length; i += instanceKlass::inner_class_next_offset) {
  2105       int ioff = inner_class_list_h->ushort_at(
  2106                       i + instanceKlass::inner_class_inner_class_info_offset);
  2108       // Inner class attribute can be zero, skip it.
  2109       // Strange but true:  JVM spec. allows null inner class refs.
  2110       if (ioff == 0) continue;
  2112       // only look at classes that are already loaded
  2113       // since we are looking for the flags for our self.
  2114       Symbol* inner_name = ik->constants()->klass_name_at(ioff);
  2115       if ((ik->name() == inner_name)) {
  2116         // This is really a member class.
  2117         access = inner_class_list_h->ushort_at(i + instanceKlass::inner_class_access_flags_offset);
  2118         break;
  2122   // Remember to strip ACC_SUPER bit
  2123   return (access & (~JVM_ACC_SUPER)) & JVM_ACC_WRITTEN_FLAGS;
  2126 jint instanceKlass::jvmti_class_status() const {
  2127   jint result = 0;
  2129   if (is_linked()) {
  2130     result |= JVMTI_CLASS_STATUS_VERIFIED | JVMTI_CLASS_STATUS_PREPARED;
  2133   if (is_initialized()) {
  2134     assert(is_linked(), "Class status is not consistent");
  2135     result |= JVMTI_CLASS_STATUS_INITIALIZED;
  2137   if (is_in_error_state()) {
  2138     result |= JVMTI_CLASS_STATUS_ERROR;
  2140   return result;
  2143 methodOop instanceKlass::method_at_itable(klassOop holder, int index, TRAPS) {
  2144   itableOffsetEntry* ioe = (itableOffsetEntry*)start_of_itable();
  2145   int method_table_offset_in_words = ioe->offset()/wordSize;
  2146   int nof_interfaces = (method_table_offset_in_words - itable_offset_in_words())
  2147                        / itableOffsetEntry::size();
  2149   for (int cnt = 0 ; ; cnt ++, ioe ++) {
  2150     // If the interface isn't implemented by the receiver class,
  2151     // the VM should throw IncompatibleClassChangeError.
  2152     if (cnt >= nof_interfaces) {
  2153       THROW_0(vmSymbols::java_lang_IncompatibleClassChangeError());
  2156     klassOop ik = ioe->interface_klass();
  2157     if (ik == holder) break;
  2160   itableMethodEntry* ime = ioe->first_method_entry(as_klassOop());
  2161   methodOop m = ime[index].method();
  2162   if (m == NULL) {
  2163     THROW_0(vmSymbols::java_lang_AbstractMethodError());
  2165   return m;
  2168 // On-stack replacement stuff
  2169 void instanceKlass::add_osr_nmethod(nmethod* n) {
  2170   // only one compilation can be active
  2171   NEEDS_CLEANUP
  2172   // This is a short non-blocking critical region, so the no safepoint check is ok.
  2173   OsrList_lock->lock_without_safepoint_check();
  2174   assert(n->is_osr_method(), "wrong kind of nmethod");
  2175   n->set_osr_link(osr_nmethods_head());
  2176   set_osr_nmethods_head(n);
  2177   // Raise the highest osr level if necessary
  2178   if (TieredCompilation) {
  2179     methodOop m = n->method();
  2180     m->set_highest_osr_comp_level(MAX2(m->highest_osr_comp_level(), n->comp_level()));
  2182   // Remember to unlock again
  2183   OsrList_lock->unlock();
  2185   // Get rid of the osr methods for the same bci that have lower levels.
  2186   if (TieredCompilation) {
  2187     for (int l = CompLevel_limited_profile; l < n->comp_level(); l++) {
  2188       nmethod *inv = lookup_osr_nmethod(n->method(), n->osr_entry_bci(), l, true);
  2189       if (inv != NULL && inv->is_in_use()) {
  2190         inv->make_not_entrant();
  2197 void instanceKlass::remove_osr_nmethod(nmethod* n) {
  2198   // This is a short non-blocking critical region, so the no safepoint check is ok.
  2199   OsrList_lock->lock_without_safepoint_check();
  2200   assert(n->is_osr_method(), "wrong kind of nmethod");
  2201   nmethod* last = NULL;
  2202   nmethod* cur  = osr_nmethods_head();
  2203   int max_level = CompLevel_none;  // Find the max comp level excluding n
  2204   methodOop m = n->method();
  2205   // Search for match
  2206   while(cur != NULL && cur != n) {
  2207     if (TieredCompilation) {
  2208       // Find max level before n
  2209       max_level = MAX2(max_level, cur->comp_level());
  2211     last = cur;
  2212     cur = cur->osr_link();
  2214   nmethod* next = NULL;
  2215   if (cur == n) {
  2216     next = cur->osr_link();
  2217     if (last == NULL) {
  2218       // Remove first element
  2219       set_osr_nmethods_head(next);
  2220     } else {
  2221       last->set_osr_link(next);
  2224   n->set_osr_link(NULL);
  2225   if (TieredCompilation) {
  2226     cur = next;
  2227     while (cur != NULL) {
  2228       // Find max level after n
  2229       max_level = MAX2(max_level, cur->comp_level());
  2230       cur = cur->osr_link();
  2232     m->set_highest_osr_comp_level(max_level);
  2234   // Remember to unlock again
  2235   OsrList_lock->unlock();
  2238 nmethod* instanceKlass::lookup_osr_nmethod(const methodOop m, int bci, int comp_level, bool match_level) const {
  2239   // This is a short non-blocking critical region, so the no safepoint check is ok.
  2240   OsrList_lock->lock_without_safepoint_check();
  2241   nmethod* osr = osr_nmethods_head();
  2242   nmethod* best = NULL;
  2243   while (osr != NULL) {
  2244     assert(osr->is_osr_method(), "wrong kind of nmethod found in chain");
  2245     // There can be a time when a c1 osr method exists but we are waiting
  2246     // for a c2 version. When c2 completes its osr nmethod we will trash
  2247     // the c1 version and only be able to find the c2 version. However
  2248     // while we overflow in the c1 code at back branches we don't want to
  2249     // try and switch to the same code as we are already running
  2251     if (osr->method() == m &&
  2252         (bci == InvocationEntryBci || osr->osr_entry_bci() == bci)) {
  2253       if (match_level) {
  2254         if (osr->comp_level() == comp_level) {
  2255           // Found a match - return it.
  2256           OsrList_lock->unlock();
  2257           return osr;
  2259       } else {
  2260         if (best == NULL || (osr->comp_level() > best->comp_level())) {
  2261           if (osr->comp_level() == CompLevel_highest_tier) {
  2262             // Found the best possible - return it.
  2263             OsrList_lock->unlock();
  2264             return osr;
  2266           best = osr;
  2270     osr = osr->osr_link();
  2272   OsrList_lock->unlock();
  2273   if (best != NULL && best->comp_level() >= comp_level && match_level == false) {
  2274     return best;
  2276   return NULL;
  2279 // -----------------------------------------------------------------------------------------------------
  2280 #ifndef PRODUCT
  2282 // Printing
  2284 #define BULLET  " - "
  2286 void FieldPrinter::do_field(fieldDescriptor* fd) {
  2287   _st->print(BULLET);
  2288    if (_obj == NULL) {
  2289      fd->print_on(_st);
  2290      _st->cr();
  2291    } else {
  2292      fd->print_on_for(_st, _obj);
  2293      _st->cr();
  2298 void instanceKlass::oop_print_on(oop obj, outputStream* st) {
  2299   Klass::oop_print_on(obj, st);
  2301   if (as_klassOop() == SystemDictionary::String_klass()) {
  2302     typeArrayOop value  = java_lang_String::value(obj);
  2303     juint        offset = java_lang_String::offset(obj);
  2304     juint        length = java_lang_String::length(obj);
  2305     if (value != NULL &&
  2306         value->is_typeArray() &&
  2307         offset          <= (juint) value->length() &&
  2308         offset + length <= (juint) value->length()) {
  2309       st->print(BULLET"string: ");
  2310       Handle h_obj(obj);
  2311       java_lang_String::print(h_obj, st);
  2312       st->cr();
  2313       if (!WizardMode)  return;  // that is enough
  2317   st->print_cr(BULLET"---- fields (total size %d words):", oop_size(obj));
  2318   FieldPrinter print_field(st, obj);
  2319   do_nonstatic_fields(&print_field);
  2321   if (as_klassOop() == SystemDictionary::Class_klass()) {
  2322     st->print(BULLET"signature: ");
  2323     java_lang_Class::print_signature(obj, st);
  2324     st->cr();
  2325     klassOop mirrored_klass = java_lang_Class::as_klassOop(obj);
  2326     st->print(BULLET"fake entry for mirror: ");
  2327     mirrored_klass->print_value_on(st);
  2328     st->cr();
  2329     st->print(BULLET"fake entry resolved_constructor: ");
  2330     methodOop ctor = java_lang_Class::resolved_constructor(obj);
  2331     ctor->print_value_on(st);
  2332     klassOop array_klass = java_lang_Class::array_klass(obj);
  2333     st->cr();
  2334     st->print(BULLET"fake entry for array: ");
  2335     array_klass->print_value_on(st);
  2336     st->cr();
  2337     st->print_cr(BULLET"fake entry for oop_size: %d", java_lang_Class::oop_size(obj));
  2338     st->print_cr(BULLET"fake entry for static_oop_field_count: %d", java_lang_Class::static_oop_field_count(obj));
  2339     klassOop real_klass = java_lang_Class::as_klassOop(obj);
  2340     if (real_klass != NULL && real_klass->klass_part()->oop_is_instance()) {
  2341       instanceKlass::cast(real_klass)->do_local_static_fields(&print_field);
  2343   } else if (as_klassOop() == SystemDictionary::MethodType_klass()) {
  2344     st->print(BULLET"signature: ");
  2345     java_lang_invoke_MethodType::print_signature(obj, st);
  2346     st->cr();
  2350 #endif //PRODUCT
  2352 void instanceKlass::oop_print_value_on(oop obj, outputStream* st) {
  2353   st->print("a ");
  2354   name()->print_value_on(st);
  2355   obj->print_address_on(st);
  2356   if (as_klassOop() == SystemDictionary::String_klass()
  2357       && java_lang_String::value(obj) != NULL) {
  2358     ResourceMark rm;
  2359     int len = java_lang_String::length(obj);
  2360     int plen = (len < 24 ? len : 12);
  2361     char* str = java_lang_String::as_utf8_string(obj, 0, plen);
  2362     st->print(" = \"%s\"", str);
  2363     if (len > plen)
  2364       st->print("...[%d]", len);
  2365   } else if (as_klassOop() == SystemDictionary::Class_klass()) {
  2366     klassOop k = java_lang_Class::as_klassOop(obj);
  2367     st->print(" = ");
  2368     if (k != NULL) {
  2369       k->print_value_on(st);
  2370     } else {
  2371       const char* tname = type2name(java_lang_Class::primitive_type(obj));
  2372       st->print("%s", tname ? tname : "type?");
  2374   } else if (as_klassOop() == SystemDictionary::MethodType_klass()) {
  2375     st->print(" = ");
  2376     java_lang_invoke_MethodType::print_signature(obj, st);
  2377   } else if (java_lang_boxing_object::is_instance(obj)) {
  2378     st->print(" = ");
  2379     java_lang_boxing_object::print(obj, st);
  2383 const char* instanceKlass::internal_name() const {
  2384   return external_name();
  2387 // Verification
  2389 class VerifyFieldClosure: public OopClosure {
  2390  protected:
  2391   template <class T> void do_oop_work(T* p) {
  2392     guarantee(Universe::heap()->is_in_closed_subset(p), "should be in heap");
  2393     oop obj = oopDesc::load_decode_heap_oop(p);
  2394     if (!obj->is_oop_or_null()) {
  2395       tty->print_cr("Failed: " PTR_FORMAT " -> " PTR_FORMAT, p, (address)obj);
  2396       Universe::print();
  2397       guarantee(false, "boom");
  2400  public:
  2401   virtual void do_oop(oop* p)       { VerifyFieldClosure::do_oop_work(p); }
  2402   virtual void do_oop(narrowOop* p) { VerifyFieldClosure::do_oop_work(p); }
  2403 };
  2405 void instanceKlass::oop_verify_on(oop obj, outputStream* st) {
  2406   Klass::oop_verify_on(obj, st);
  2407   VerifyFieldClosure blk;
  2408   oop_oop_iterate(obj, &blk);
  2411 #ifndef PRODUCT
  2413 void instanceKlass::verify_class_klass_nonstatic_oop_maps(klassOop k) {
  2414   // This verification code is disabled.  JDK_Version::is_gte_jdk14x_version()
  2415   // cannot be called since this function is called before the VM is
  2416   // able to determine what JDK version is running with.
  2417   // The check below always is false since 1.4.
  2418   return;
  2420   // This verification code temporarily disabled for the 1.4
  2421   // reflection implementation since java.lang.Class now has
  2422   // Java-level instance fields. Should rewrite this to handle this
  2423   // case.
  2424   if (!(JDK_Version::is_gte_jdk14x_version() && UseNewReflection)) {
  2425     // Verify that java.lang.Class instances have a fake oop field added.
  2426     instanceKlass* ik = instanceKlass::cast(k);
  2428     // Check that we have the right class
  2429     static bool first_time = true;
  2430     guarantee(k == SystemDictionary::Class_klass() && first_time, "Invalid verify of maps");
  2431     first_time = false;
  2432     const int extra = java_lang_Class::number_of_fake_oop_fields;
  2433     guarantee(ik->nonstatic_field_size() == extra, "just checking");
  2434     guarantee(ik->nonstatic_oop_map_count() == 1, "just checking");
  2435     guarantee(ik->size_helper() == align_object_size(instanceOopDesc::header_size() + extra), "just checking");
  2437     // Check that the map is (2,extra)
  2438     int offset = java_lang_Class::klass_offset;
  2440     OopMapBlock* map = ik->start_of_nonstatic_oop_maps();
  2441     guarantee(map->offset() == offset && map->count() == (unsigned int) extra,
  2442               "sanity");
  2446 #endif // ndef PRODUCT
  2448 // JNIid class for jfieldIDs only
  2449 // Note to reviewers:
  2450 // These JNI functions are just moved over to column 1 and not changed
  2451 // in the compressed oops workspace.
  2452 JNIid::JNIid(klassOop holder, int offset, JNIid* next) {
  2453   _holder = holder;
  2454   _offset = offset;
  2455   _next = next;
  2456   debug_only(_is_static_field_id = false;)
  2460 JNIid* JNIid::find(int offset) {
  2461   JNIid* current = this;
  2462   while (current != NULL) {
  2463     if (current->offset() == offset) return current;
  2464     current = current->next();
  2466   return NULL;
  2469 void JNIid::oops_do(OopClosure* f) {
  2470   for (JNIid* cur = this; cur != NULL; cur = cur->next()) {
  2471     f->do_oop(cur->holder_addr());
  2475 void JNIid::deallocate(JNIid* current) {
  2476   while (current != NULL) {
  2477     JNIid* next = current->next();
  2478     delete current;
  2479     current = next;
  2484 void JNIid::verify(klassOop holder) {
  2485   int first_field_offset  = instanceMirrorKlass::offset_of_static_fields();
  2486   int end_field_offset;
  2487   end_field_offset = first_field_offset + (instanceKlass::cast(holder)->static_field_size() * wordSize);
  2489   JNIid* current = this;
  2490   while (current != NULL) {
  2491     guarantee(current->holder() == holder, "Invalid klass in JNIid");
  2492 #ifdef ASSERT
  2493     int o = current->offset();
  2494     if (current->is_static_field_id()) {
  2495       guarantee(o >= first_field_offset  && o < end_field_offset,  "Invalid static field offset in JNIid");
  2497 #endif
  2498     current = current->next();
  2503 #ifdef ASSERT
  2504 void instanceKlass::set_init_state(ClassState state) {
  2505   bool good_state = as_klassOop()->is_shared() ? (_init_state <= state)
  2506                                                : (_init_state < state);
  2507   assert(good_state || state == allocated, "illegal state transition");
  2508   _init_state = state;
  2510 #endif
  2513 // RedefineClasses() support for previous versions:
  2515 // Add an information node that contains weak references to the
  2516 // interesting parts of the previous version of the_class.
  2517 // This is also where we clean out any unused weak references.
  2518 // Note that while we delete nodes from the _previous_versions
  2519 // array, we never delete the array itself until the klass is
  2520 // unloaded. The has_been_redefined() query depends on that fact.
  2521 //
  2522 void instanceKlass::add_previous_version(instanceKlassHandle ikh,
  2523        BitMap* emcp_methods, int emcp_method_count) {
  2524   assert(Thread::current()->is_VM_thread(),
  2525          "only VMThread can add previous versions");
  2527   if (_previous_versions == NULL) {
  2528     // This is the first previous version so make some space.
  2529     // Start with 2 elements under the assumption that the class
  2530     // won't be redefined much.
  2531     _previous_versions =  new (ResourceObj::C_HEAP)
  2532                             GrowableArray<PreviousVersionNode *>(2, true);
  2535   // RC_TRACE macro has an embedded ResourceMark
  2536   RC_TRACE(0x00000100, ("adding previous version ref for %s @%d, EMCP_cnt=%d",
  2537     ikh->external_name(), _previous_versions->length(), emcp_method_count));
  2538   constantPoolHandle cp_h(ikh->constants());
  2539   jobject cp_ref;
  2540   if (cp_h->is_shared()) {
  2541     // a shared ConstantPool requires a regular reference; a weak
  2542     // reference would be collectible
  2543     cp_ref = JNIHandles::make_global(cp_h);
  2544   } else {
  2545     cp_ref = JNIHandles::make_weak_global(cp_h);
  2547   PreviousVersionNode * pv_node = NULL;
  2548   objArrayOop old_methods = ikh->methods();
  2550   if (emcp_method_count == 0) {
  2551     // non-shared ConstantPool gets a weak reference
  2552     pv_node = new PreviousVersionNode(cp_ref, !cp_h->is_shared(), NULL);
  2553     RC_TRACE(0x00000400,
  2554       ("add: all methods are obsolete; flushing any EMCP weak refs"));
  2555   } else {
  2556     int local_count = 0;
  2557     GrowableArray<jweak>* method_refs = new (ResourceObj::C_HEAP)
  2558       GrowableArray<jweak>(emcp_method_count, true);
  2559     for (int i = 0; i < old_methods->length(); i++) {
  2560       if (emcp_methods->at(i)) {
  2561         // this old method is EMCP so save a weak ref
  2562         methodOop old_method = (methodOop) old_methods->obj_at(i);
  2563         methodHandle old_method_h(old_method);
  2564         jweak method_ref = JNIHandles::make_weak_global(old_method_h);
  2565         method_refs->append(method_ref);
  2566         if (++local_count >= emcp_method_count) {
  2567           // no more EMCP methods so bail out now
  2568           break;
  2572     // non-shared ConstantPool gets a weak reference
  2573     pv_node = new PreviousVersionNode(cp_ref, !cp_h->is_shared(), method_refs);
  2576   _previous_versions->append(pv_node);
  2578   // Using weak references allows the interesting parts of previous
  2579   // classes to be GC'ed when they are no longer needed. Since the
  2580   // caller is the VMThread and we are at a safepoint, this is a good
  2581   // time to clear out unused weak references.
  2583   RC_TRACE(0x00000400, ("add: previous version length=%d",
  2584     _previous_versions->length()));
  2586   // skip the last entry since we just added it
  2587   for (int i = _previous_versions->length() - 2; i >= 0; i--) {
  2588     // check the previous versions array for a GC'ed weak refs
  2589     pv_node = _previous_versions->at(i);
  2590     cp_ref = pv_node->prev_constant_pool();
  2591     assert(cp_ref != NULL, "cp ref was unexpectedly cleared");
  2592     if (cp_ref == NULL) {
  2593       delete pv_node;
  2594       _previous_versions->remove_at(i);
  2595       // Since we are traversing the array backwards, we don't have to
  2596       // do anything special with the index.
  2597       continue;  // robustness
  2600     constantPoolOop cp = (constantPoolOop)JNIHandles::resolve(cp_ref);
  2601     if (cp == NULL) {
  2602       // this entry has been GC'ed so remove it
  2603       delete pv_node;
  2604       _previous_versions->remove_at(i);
  2605       // Since we are traversing the array backwards, we don't have to
  2606       // do anything special with the index.
  2607       continue;
  2608     } else {
  2609       RC_TRACE(0x00000400, ("add: previous version @%d is alive", i));
  2612     GrowableArray<jweak>* method_refs = pv_node->prev_EMCP_methods();
  2613     if (method_refs != NULL) {
  2614       RC_TRACE(0x00000400, ("add: previous methods length=%d",
  2615         method_refs->length()));
  2616       for (int j = method_refs->length() - 1; j >= 0; j--) {
  2617         jweak method_ref = method_refs->at(j);
  2618         assert(method_ref != NULL, "weak method ref was unexpectedly cleared");
  2619         if (method_ref == NULL) {
  2620           method_refs->remove_at(j);
  2621           // Since we are traversing the array backwards, we don't have to
  2622           // do anything special with the index.
  2623           continue;  // robustness
  2626         methodOop method = (methodOop)JNIHandles::resolve(method_ref);
  2627         if (method == NULL || emcp_method_count == 0) {
  2628           // This method entry has been GC'ed or the current
  2629           // RedefineClasses() call has made all methods obsolete
  2630           // so remove it.
  2631           JNIHandles::destroy_weak_global(method_ref);
  2632           method_refs->remove_at(j);
  2633         } else {
  2634           // RC_TRACE macro has an embedded ResourceMark
  2635           RC_TRACE(0x00000400,
  2636             ("add: %s(%s): previous method @%d in version @%d is alive",
  2637             method->name()->as_C_string(), method->signature()->as_C_string(),
  2638             j, i));
  2644   int obsolete_method_count = old_methods->length() - emcp_method_count;
  2646   if (emcp_method_count != 0 && obsolete_method_count != 0 &&
  2647       _previous_versions->length() > 1) {
  2648     // We have a mix of obsolete and EMCP methods. If there is more
  2649     // than the previous version that we just added, then we have to
  2650     // clear out any matching EMCP method entries the hard way.
  2651     int local_count = 0;
  2652     for (int i = 0; i < old_methods->length(); i++) {
  2653       if (!emcp_methods->at(i)) {
  2654         // only obsolete methods are interesting
  2655         methodOop old_method = (methodOop) old_methods->obj_at(i);
  2656         Symbol* m_name = old_method->name();
  2657         Symbol* m_signature = old_method->signature();
  2659         // skip the last entry since we just added it
  2660         for (int j = _previous_versions->length() - 2; j >= 0; j--) {
  2661           // check the previous versions array for a GC'ed weak refs
  2662           pv_node = _previous_versions->at(j);
  2663           cp_ref = pv_node->prev_constant_pool();
  2664           assert(cp_ref != NULL, "cp ref was unexpectedly cleared");
  2665           if (cp_ref == NULL) {
  2666             delete pv_node;
  2667             _previous_versions->remove_at(j);
  2668             // Since we are traversing the array backwards, we don't have to
  2669             // do anything special with the index.
  2670             continue;  // robustness
  2673           constantPoolOop cp = (constantPoolOop)JNIHandles::resolve(cp_ref);
  2674           if (cp == NULL) {
  2675             // this entry has been GC'ed so remove it
  2676             delete pv_node;
  2677             _previous_versions->remove_at(j);
  2678             // Since we are traversing the array backwards, we don't have to
  2679             // do anything special with the index.
  2680             continue;
  2683           GrowableArray<jweak>* method_refs = pv_node->prev_EMCP_methods();
  2684           if (method_refs == NULL) {
  2685             // We have run into a PreviousVersion generation where
  2686             // all methods were made obsolete during that generation's
  2687             // RedefineClasses() operation. At the time of that
  2688             // operation, all EMCP methods were flushed so we don't
  2689             // have to go back any further.
  2690             //
  2691             // A NULL method_refs is different than an empty method_refs.
  2692             // We cannot infer any optimizations about older generations
  2693             // from an empty method_refs for the current generation.
  2694             break;
  2697           for (int k = method_refs->length() - 1; k >= 0; k--) {
  2698             jweak method_ref = method_refs->at(k);
  2699             assert(method_ref != NULL,
  2700               "weak method ref was unexpectedly cleared");
  2701             if (method_ref == NULL) {
  2702               method_refs->remove_at(k);
  2703               // Since we are traversing the array backwards, we don't
  2704               // have to do anything special with the index.
  2705               continue;  // robustness
  2708             methodOop method = (methodOop)JNIHandles::resolve(method_ref);
  2709             if (method == NULL) {
  2710               // this method entry has been GC'ed so skip it
  2711               JNIHandles::destroy_weak_global(method_ref);
  2712               method_refs->remove_at(k);
  2713               continue;
  2716             if (method->name() == m_name &&
  2717                 method->signature() == m_signature) {
  2718               // The current RedefineClasses() call has made all EMCP
  2719               // versions of this method obsolete so mark it as obsolete
  2720               // and remove the weak ref.
  2721               RC_TRACE(0x00000400,
  2722                 ("add: %s(%s): flush obsolete method @%d in version @%d",
  2723                 m_name->as_C_string(), m_signature->as_C_string(), k, j));
  2725               method->set_is_obsolete();
  2726               JNIHandles::destroy_weak_global(method_ref);
  2727               method_refs->remove_at(k);
  2728               break;
  2732           // The previous loop may not find a matching EMCP method, but
  2733           // that doesn't mean that we can optimize and not go any
  2734           // further back in the PreviousVersion generations. The EMCP
  2735           // method for this generation could have already been GC'ed,
  2736           // but there still may be an older EMCP method that has not
  2737           // been GC'ed.
  2740         if (++local_count >= obsolete_method_count) {
  2741           // no more obsolete methods so bail out now
  2742           break;
  2747 } // end add_previous_version()
  2750 // Determine if instanceKlass has a previous version.
  2751 bool instanceKlass::has_previous_version() const {
  2752   if (_previous_versions == NULL) {
  2753     // no previous versions array so answer is easy
  2754     return false;
  2757   for (int i = _previous_versions->length() - 1; i >= 0; i--) {
  2758     // Check the previous versions array for an info node that hasn't
  2759     // been GC'ed
  2760     PreviousVersionNode * pv_node = _previous_versions->at(i);
  2762     jobject cp_ref = pv_node->prev_constant_pool();
  2763     assert(cp_ref != NULL, "cp reference was unexpectedly cleared");
  2764     if (cp_ref == NULL) {
  2765       continue;  // robustness
  2768     constantPoolOop cp = (constantPoolOop)JNIHandles::resolve(cp_ref);
  2769     if (cp != NULL) {
  2770       // we have at least one previous version
  2771       return true;
  2774     // We don't have to check the method refs. If the constant pool has
  2775     // been GC'ed then so have the methods.
  2778   // all of the underlying nodes' info has been GC'ed
  2779   return false;
  2780 } // end has_previous_version()
  2782 methodOop instanceKlass::method_with_idnum(int idnum) {
  2783   methodOop m = NULL;
  2784   if (idnum < methods()->length()) {
  2785     m = (methodOop) methods()->obj_at(idnum);
  2787   if (m == NULL || m->method_idnum() != idnum) {
  2788     for (int index = 0; index < methods()->length(); ++index) {
  2789       m = (methodOop) methods()->obj_at(index);
  2790       if (m->method_idnum() == idnum) {
  2791         return m;
  2795   return m;
  2799 // Set the annotation at 'idnum' to 'anno'.
  2800 // We don't want to create or extend the array if 'anno' is NULL, since that is the
  2801 // default value.  However, if the array exists and is long enough, we must set NULL values.
  2802 void instanceKlass::set_methods_annotations_of(int idnum, typeArrayOop anno, objArrayOop* md_p) {
  2803   objArrayOop md = *md_p;
  2804   if (md != NULL && md->length() > idnum) {
  2805     md->obj_at_put(idnum, anno);
  2806   } else if (anno != NULL) {
  2807     // create the array
  2808     int length = MAX2(idnum+1, (int)_idnum_allocated_count);
  2809     md = oopFactory::new_system_objArray(length, Thread::current());
  2810     if (*md_p != NULL) {
  2811       // copy the existing entries
  2812       for (int index = 0; index < (*md_p)->length(); index++) {
  2813         md->obj_at_put(index, (*md_p)->obj_at(index));
  2816     set_annotations(md, md_p);
  2817     md->obj_at_put(idnum, anno);
  2818   } // if no array and idnum isn't included there is nothing to do
  2821 // Construct a PreviousVersionNode entry for the array hung off
  2822 // the instanceKlass.
  2823 PreviousVersionNode::PreviousVersionNode(jobject prev_constant_pool,
  2824   bool prev_cp_is_weak, GrowableArray<jweak>* prev_EMCP_methods) {
  2826   _prev_constant_pool = prev_constant_pool;
  2827   _prev_cp_is_weak = prev_cp_is_weak;
  2828   _prev_EMCP_methods = prev_EMCP_methods;
  2832 // Destroy a PreviousVersionNode
  2833 PreviousVersionNode::~PreviousVersionNode() {
  2834   if (_prev_constant_pool != NULL) {
  2835     if (_prev_cp_is_weak) {
  2836       JNIHandles::destroy_weak_global(_prev_constant_pool);
  2837     } else {
  2838       JNIHandles::destroy_global(_prev_constant_pool);
  2842   if (_prev_EMCP_methods != NULL) {
  2843     for (int i = _prev_EMCP_methods->length() - 1; i >= 0; i--) {
  2844       jweak method_ref = _prev_EMCP_methods->at(i);
  2845       if (method_ref != NULL) {
  2846         JNIHandles::destroy_weak_global(method_ref);
  2849     delete _prev_EMCP_methods;
  2854 // Construct a PreviousVersionInfo entry
  2855 PreviousVersionInfo::PreviousVersionInfo(PreviousVersionNode *pv_node) {
  2856   _prev_constant_pool_handle = constantPoolHandle();  // NULL handle
  2857   _prev_EMCP_method_handles = NULL;
  2859   jobject cp_ref = pv_node->prev_constant_pool();
  2860   assert(cp_ref != NULL, "constant pool ref was unexpectedly cleared");
  2861   if (cp_ref == NULL) {
  2862     return;  // robustness
  2865   constantPoolOop cp = (constantPoolOop)JNIHandles::resolve(cp_ref);
  2866   if (cp == NULL) {
  2867     // Weak reference has been GC'ed. Since the constant pool has been
  2868     // GC'ed, the methods have also been GC'ed.
  2869     return;
  2872   // make the constantPoolOop safe to return
  2873   _prev_constant_pool_handle = constantPoolHandle(cp);
  2875   GrowableArray<jweak>* method_refs = pv_node->prev_EMCP_methods();
  2876   if (method_refs == NULL) {
  2877     // the instanceKlass did not have any EMCP methods
  2878     return;
  2881   _prev_EMCP_method_handles = new GrowableArray<methodHandle>(10);
  2883   int n_methods = method_refs->length();
  2884   for (int i = 0; i < n_methods; i++) {
  2885     jweak method_ref = method_refs->at(i);
  2886     assert(method_ref != NULL, "weak method ref was unexpectedly cleared");
  2887     if (method_ref == NULL) {
  2888       continue;  // robustness
  2891     methodOop method = (methodOop)JNIHandles::resolve(method_ref);
  2892     if (method == NULL) {
  2893       // this entry has been GC'ed so skip it
  2894       continue;
  2897     // make the methodOop safe to return
  2898     _prev_EMCP_method_handles->append(methodHandle(method));
  2903 // Destroy a PreviousVersionInfo
  2904 PreviousVersionInfo::~PreviousVersionInfo() {
  2905   // Since _prev_EMCP_method_handles is not C-heap allocated, we
  2906   // don't have to delete it.
  2910 // Construct a helper for walking the previous versions array
  2911 PreviousVersionWalker::PreviousVersionWalker(instanceKlass *ik) {
  2912   _previous_versions = ik->previous_versions();
  2913   _current_index = 0;
  2914   // _hm needs no initialization
  2915   _current_p = NULL;
  2919 // Destroy a PreviousVersionWalker
  2920 PreviousVersionWalker::~PreviousVersionWalker() {
  2921   // Delete the current info just in case the caller didn't walk to
  2922   // the end of the previous versions list. No harm if _current_p is
  2923   // already NULL.
  2924   delete _current_p;
  2926   // When _hm is destroyed, all the Handles returned in
  2927   // PreviousVersionInfo objects will be destroyed.
  2928   // Also, after this destructor is finished it will be
  2929   // safe to delete the GrowableArray allocated in the
  2930   // PreviousVersionInfo objects.
  2934 // Return the interesting information for the next previous version
  2935 // of the klass. Returns NULL if there are no more previous versions.
  2936 PreviousVersionInfo* PreviousVersionWalker::next_previous_version() {
  2937   if (_previous_versions == NULL) {
  2938     // no previous versions so nothing to return
  2939     return NULL;
  2942   delete _current_p;  // cleanup the previous info for the caller
  2943   _current_p = NULL;  // reset to NULL so we don't delete same object twice
  2945   int length = _previous_versions->length();
  2947   while (_current_index < length) {
  2948     PreviousVersionNode * pv_node = _previous_versions->at(_current_index++);
  2949     PreviousVersionInfo * pv_info = new (ResourceObj::C_HEAP)
  2950                                           PreviousVersionInfo(pv_node);
  2952     constantPoolHandle cp_h = pv_info->prev_constant_pool_handle();
  2953     if (cp_h.is_null()) {
  2954       delete pv_info;
  2956       // The underlying node's info has been GC'ed so try the next one.
  2957       // We don't have to check the methods. If the constant pool has
  2958       // GC'ed then so have the methods.
  2959       continue;
  2962     // Found a node with non GC'ed info so return it. The caller will
  2963     // need to delete pv_info when they are done with it.
  2964     _current_p = pv_info;
  2965     return pv_info;
  2968   // all of the underlying nodes' info has been GC'ed
  2969   return NULL;
  2970 } // end next_previous_version()

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