1 /*
   2  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoader.hpp"
  27 #include "classfile/symbolTable.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "compiler/compileBroker.hpp"
  31 #include "compiler/compilerOracle.hpp"
  32 #include "interpreter/bytecodeHistogram.hpp"
  33 #include "memory/genCollectedHeap.hpp"
  34 #include "memory/oopFactory.hpp"
  35 #include "memory/universe.hpp"
  36 #include "oops/constantPoolOop.hpp"
  37 #include "oops/generateOopMap.hpp"
  38 #include "oops/instanceKlass.hpp"
  39 #include "oops/instanceKlassKlass.hpp"
  40 #include "oops/instanceOop.hpp"
  41 #include "oops/methodOop.hpp"
  42 #include "oops/objArrayOop.hpp"
  43 #include "oops/oop.inline.hpp"
  44 #include "oops/symbolOop.hpp"
  45 #include "prims/jvmtiExport.hpp"
  46 #include "runtime/aprofiler.hpp"
  47 #include "runtime/arguments.hpp"
  48 #include "runtime/biasedLocking.hpp"
  49 #include "runtime/compilationPolicy.hpp"
  50 #include "runtime/fprofiler.hpp"
  51 #include "runtime/init.hpp"
  52 #include "runtime/interfaceSupport.hpp"
  53 #include "runtime/java.hpp"
  54 #include "runtime/memprofiler.hpp"
  55 #include "runtime/sharedRuntime.hpp"
  56 #include "runtime/statSampler.hpp"
  57 #include "runtime/task.hpp"
  58 #include "runtime/timer.hpp"
  59 #include "runtime/vm_operations.hpp"
  60 #include "utilities/dtrace.hpp"
  61 #include "utilities/globalDefinitions.hpp"
  62 #include "utilities/histogram.hpp"
  63 #include "utilities/vmError.hpp"
  64 #ifdef TARGET_ARCH_x86
  65 # include "vm_version_x86.hpp"
  66 #endif
  67 #ifdef TARGET_ARCH_sparc
  68 # include "vm_version_sparc.hpp"
  69 #endif
  70 #ifdef TARGET_ARCH_zero
  71 # include "vm_version_zero.hpp"
  72 #endif
  73 #ifdef TARGET_OS_FAMILY_linux
  74 # include "thread_linux.inline.hpp"
  75 #endif
  76 #ifdef TARGET_OS_FAMILY_solaris
  77 # include "thread_solaris.inline.hpp"
  78 #endif
  79 #ifdef TARGET_OS_FAMILY_windows
  80 # include "thread_windows.inline.hpp"
  81 #endif
  82 #ifndef SERIALGC
  83 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
  84 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
  85 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
  86 #endif
  87 #ifdef COMPILER1
  88 #include "c1/c1_Compiler.hpp"
  89 #include "c1/c1_Runtime1.hpp"
  90 #endif
  91 #ifdef COMPILER2
  92 #include "code/compiledIC.hpp"
  93 #include "compiler/methodLiveness.hpp"
  94 #include "opto/compile.hpp"
  95 #include "opto/indexSet.hpp"
  96 #include "opto/runtime.hpp"
  97 #endif
  98 
  99 HS_DTRACE_PROBE_DECL(hotspot, vm__shutdown);
 100 
 101 #ifndef PRODUCT
 102 
 103 // Statistics printing (method invocation histogram)
 104 
 105 GrowableArray<methodOop>* collected_invoked_methods;
 106 
 107 void collect_invoked_methods(methodOop m) {
 108   if (m->invocation_count() + m->compiled_invocation_count() >= 1 ) {
 109     collected_invoked_methods->push(m);
 110   }
 111 }
 112 
 113 
 114 GrowableArray<methodOop>* collected_profiled_methods;
 115 
 116 void collect_profiled_methods(methodOop m) {
 117   methodHandle mh(Thread::current(), m);
 118   if ((m->method_data() != NULL) &&
 119       (PrintMethodData || CompilerOracle::should_print(mh))) {
 120     collected_profiled_methods->push(m);
 121   }
 122 }
 123 
 124 
 125 int compare_methods(methodOop* a, methodOop* b) {
 126   // %%% there can be 32-bit overflow here
 127   return ((*b)->invocation_count() + (*b)->compiled_invocation_count())
 128        - ((*a)->invocation_count() + (*a)->compiled_invocation_count());
 129 }
 130 
 131 
 132 void print_method_invocation_histogram() {
 133   ResourceMark rm;
 134   HandleMark hm;
 135   collected_invoked_methods = new GrowableArray<methodOop>(1024);
 136   SystemDictionary::methods_do(collect_invoked_methods);
 137   collected_invoked_methods->sort(&compare_methods);
 138   //
 139   tty->cr();
 140   tty->print_cr("Histogram Over MethodOop Invocation Counters (cutoff = %d):", MethodHistogramCutoff);
 141   tty->cr();
 142   tty->print_cr("____Count_(I+C)____Method________________________Module_________________");
 143   unsigned total = 0, int_total = 0, comp_total = 0, static_total = 0, final_total = 0,
 144       synch_total = 0, nativ_total = 0, acces_total = 0;
 145   for (int index = 0; index < collected_invoked_methods->length(); index++) {
 146     methodOop m = collected_invoked_methods->at(index);
 147     int c = m->invocation_count() + m->compiled_invocation_count();
 148     if (c >= MethodHistogramCutoff) m->print_invocation_count();
 149     int_total  += m->invocation_count();
 150     comp_total += m->compiled_invocation_count();
 151     if (m->is_final())        final_total  += c;
 152     if (m->is_static())       static_total += c;
 153     if (m->is_synchronized()) synch_total  += c;
 154     if (m->is_native())       nativ_total  += c;
 155     if (m->is_accessor())     acces_total  += c;
 156   }
 157   tty->cr();
 158   total = int_total + comp_total;
 159   tty->print_cr("Invocations summary:");
 160   tty->print_cr("\t%9d (%4.1f%%) interpreted",  int_total,    100.0 * int_total    / total);
 161   tty->print_cr("\t%9d (%4.1f%%) compiled",     comp_total,   100.0 * comp_total   / total);
 162   tty->print_cr("\t%9d (100%%)  total",         total);
 163   tty->print_cr("\t%9d (%4.1f%%) synchronized", synch_total,  100.0 * synch_total  / total);
 164   tty->print_cr("\t%9d (%4.1f%%) final",        final_total,  100.0 * final_total  / total);
 165   tty->print_cr("\t%9d (%4.1f%%) static",       static_total, 100.0 * static_total / total);
 166   tty->print_cr("\t%9d (%4.1f%%) native",       nativ_total,  100.0 * nativ_total  / total);
 167   tty->print_cr("\t%9d (%4.1f%%) accessor",     acces_total,  100.0 * acces_total  / total);
 168   tty->cr();
 169   SharedRuntime::print_call_statistics(comp_total);
 170 }
 171 
 172 void print_method_profiling_data() {
 173   ResourceMark rm;
 174   HandleMark hm;
 175   collected_profiled_methods = new GrowableArray<methodOop>(1024);
 176   SystemDictionary::methods_do(collect_profiled_methods);
 177   collected_profiled_methods->sort(&compare_methods);
 178 
 179   int count = collected_profiled_methods->length();
 180   if (count > 0) {
 181     for (int index = 0; index < count; index++) {
 182       methodOop m = collected_profiled_methods->at(index);
 183       ttyLocker ttyl;
 184       tty->print_cr("------------------------------------------------------------------------");
 185       //m->print_name(tty);
 186       m->print_invocation_count();
 187       tty->cr();
 188       m->print_codes();
 189     }
 190     tty->print_cr("------------------------------------------------------------------------");
 191   }
 192 }
 193 
 194 void print_bytecode_count() {
 195   if (CountBytecodes || TraceBytecodes || StopInterpreterAt) {
 196     tty->print_cr("[BytecodeCounter::counter_value = %d]", BytecodeCounter::counter_value());
 197   }
 198 }
 199 
 200 AllocStats alloc_stats;
 201 
 202 
 203 
 204 // General statistics printing (profiling ...)
 205 
 206 void print_statistics() {
 207 
 208 #ifdef ASSERT
 209 
 210   if (CountRuntimeCalls) {
 211     extern Histogram *RuntimeHistogram;
 212     RuntimeHistogram->print();
 213   }
 214 
 215   if (CountJNICalls) {
 216     extern Histogram *JNIHistogram;
 217     JNIHistogram->print();
 218   }
 219 
 220   if (CountJVMCalls) {
 221     extern Histogram *JVMHistogram;
 222     JVMHistogram->print();
 223   }
 224 
 225 #endif
 226 
 227   if (MemProfiling) {
 228     MemProfiler::disengage();
 229   }
 230 
 231   if (CITime) {
 232     CompileBroker::print_times();
 233   }
 234 
 235 #ifdef COMPILER1
 236   if ((PrintC1Statistics || LogVMOutput || LogCompilation) && UseCompiler) {
 237     FlagSetting fs(DisplayVMOutput, DisplayVMOutput && PrintC1Statistics);
 238     Runtime1::print_statistics();
 239     Deoptimization::print_statistics();
 240     nmethod::print_statistics();
 241   }
 242 #endif /* COMPILER1 */
 243 
 244 #ifdef COMPILER2
 245   if ((PrintOptoStatistics || LogVMOutput || LogCompilation) && UseCompiler) {
 246     FlagSetting fs(DisplayVMOutput, DisplayVMOutput && PrintOptoStatistics);
 247     Compile::print_statistics();
 248 #ifndef COMPILER1
 249     Deoptimization::print_statistics();
 250     nmethod::print_statistics();
 251 #endif //COMPILER1
 252     SharedRuntime::print_statistics();
 253     os::print_statistics();
 254   }
 255 
 256   if (PrintLockStatistics || PrintPreciseBiasedLockingStatistics) {
 257     OptoRuntime::print_named_counters();
 258   }
 259 
 260   if (TimeLivenessAnalysis) {
 261     MethodLiveness::print_times();
 262   }
 263 #ifdef ASSERT
 264   if (CollectIndexSetStatistics) {
 265     IndexSet::print_statistics();
 266   }
 267 #endif // ASSERT
 268 #endif // COMPILER2
 269   if (CountCompiledCalls) {
 270     print_method_invocation_histogram();
 271   }
 272   if (ProfileInterpreter || C1UpdateMethodData) {
 273     print_method_profiling_data();
 274   }
 275   if (TimeCompiler) {
 276     COMPILER2_PRESENT(Compile::print_timers();)
 277   }
 278   if (TimeCompilationPolicy) {
 279     CompilationPolicy::policy()->print_time();
 280   }
 281   if (TimeOopMap) {
 282     GenerateOopMap::print_time();
 283   }
 284   if (ProfilerCheckIntervals) {
 285     PeriodicTask::print_intervals();
 286   }
 287   if (PrintSymbolTableSizeHistogram) {
 288     SymbolTable::print_histogram();
 289   }
 290   if (CountBytecodes || TraceBytecodes || StopInterpreterAt) {
 291     BytecodeCounter::print();
 292   }
 293   if (PrintBytecodePairHistogram) {
 294     BytecodePairHistogram::print();
 295   }
 296 
 297   if (PrintCodeCache) {
 298     MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
 299     CodeCache::print();
 300   }
 301 
 302   if (PrintCodeCache2) {
 303     MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
 304     CodeCache::print_internals();
 305   }
 306 
 307   if (PrintClassStatistics) {
 308     SystemDictionary::print_class_statistics();
 309   }
 310   if (PrintMethodStatistics) {
 311     SystemDictionary::print_method_statistics();
 312   }
 313 
 314   if (PrintVtableStats) {
 315     klassVtable::print_statistics();
 316     klassItable::print_statistics();
 317   }
 318   if (VerifyOops) {
 319     tty->print_cr("+VerifyOops count: %d", StubRoutines::verify_oop_count());
 320   }
 321 
 322   print_bytecode_count();
 323   if (WizardMode) {
 324     tty->print("allocation stats: ");
 325     alloc_stats.print();
 326     tty->cr();
 327   }
 328 
 329   if (PrintSystemDictionaryAtExit) {
 330     SystemDictionary::print();
 331   }
 332 
 333   if (PrintBiasedLockingStatistics) {
 334     BiasedLocking::print_counters();
 335   }
 336 
 337 #ifdef ENABLE_ZAP_DEAD_LOCALS
 338 #ifdef COMPILER2
 339   if (ZapDeadCompiledLocals) {
 340     tty->print_cr("Compile::CompiledZap_count = %d", Compile::CompiledZap_count);
 341     tty->print_cr("OptoRuntime::ZapDeadCompiledLocals_count = %d", OptoRuntime::ZapDeadCompiledLocals_count);
 342   }
 343 #endif // COMPILER2
 344 #endif // ENABLE_ZAP_DEAD_LOCALS
 345 }
 346 
 347 #else // PRODUCT MODE STATISTICS
 348 
 349 void print_statistics() {
 350 
 351   if (CITime) {
 352     CompileBroker::print_times();
 353   }
 354 #ifdef COMPILER2
 355   if (PrintPreciseBiasedLockingStatistics) {
 356     OptoRuntime::print_named_counters();
 357   }
 358 #endif
 359   if (PrintBiasedLockingStatistics) {
 360     BiasedLocking::print_counters();
 361   }
 362 }
 363 
 364 #endif
 365 
 366 
 367 // Helper class for registering on_exit calls through JVM_OnExit
 368 
 369 extern "C" {
 370     typedef void (*__exit_proc)(void);
 371 }
 372 
 373 class ExitProc : public CHeapObj {
 374  private:
 375   __exit_proc _proc;
 376   // void (*_proc)(void);
 377   ExitProc* _next;
 378  public:
 379   // ExitProc(void (*proc)(void)) {
 380   ExitProc(__exit_proc proc) {
 381     _proc = proc;
 382     _next = NULL;
 383   }
 384   void evaluate()               { _proc(); }
 385   ExitProc* next() const        { return _next; }
 386   void set_next(ExitProc* next) { _next = next; }
 387 };
 388 
 389 
 390 // Linked list of registered on_exit procedures
 391 
 392 static ExitProc* exit_procs = NULL;
 393 
 394 
 395 extern "C" {
 396   void register_on_exit_function(void (*func)(void)) {
 397     ExitProc *entry = new ExitProc(func);
 398     // Classic vm does not throw an exception in case the allocation failed,
 399     if (entry != NULL) {
 400       entry->set_next(exit_procs);
 401       exit_procs = entry;
 402     }
 403   }
 404 }
 405 
 406 // Note: before_exit() can be executed only once, if more than one threads
 407 //       are trying to shutdown the VM at the same time, only one thread
 408 //       can run before_exit() and all other threads must wait.
 409 void before_exit(JavaThread * thread) {
 410   #define BEFORE_EXIT_NOT_RUN 0
 411   #define BEFORE_EXIT_RUNNING 1
 412   #define BEFORE_EXIT_DONE    2
 413   static jint volatile _before_exit_status = BEFORE_EXIT_NOT_RUN;
 414 
 415   // Note: don't use a Mutex to guard the entire before_exit(), as
 416   // JVMTI post_thread_end_event and post_vm_death_event will run native code.
 417   // A CAS or OSMutex would work just fine but then we need to manipulate
 418   // thread state for Safepoint. Here we use Monitor wait() and notify_all()
 419   // for synchronization.
 420   { MutexLocker ml(BeforeExit_lock);
 421     switch (_before_exit_status) {
 422     case BEFORE_EXIT_NOT_RUN:
 423       _before_exit_status = BEFORE_EXIT_RUNNING;
 424       break;
 425     case BEFORE_EXIT_RUNNING:
 426       while (_before_exit_status == BEFORE_EXIT_RUNNING) {
 427         BeforeExit_lock->wait();
 428       }
 429       assert(_before_exit_status == BEFORE_EXIT_DONE, "invalid state");
 430       return;
 431     case BEFORE_EXIT_DONE:
 432       return;
 433     }
 434   }
 435 
 436   // The only difference between this and Win32's _onexit procs is that
 437   // this version is invoked before any threads get killed.
 438   ExitProc* current = exit_procs;
 439   while (current != NULL) {
 440     ExitProc* next = current->next();
 441     current->evaluate();
 442     delete current;
 443     current = next;
 444   }
 445 
 446   // Hang forever on exit if we're reporting an error.
 447   if (ShowMessageBoxOnError && is_error_reported()) {
 448     os::infinite_sleep();
 449   }
 450 
 451   // Terminate watcher thread - must before disenrolling any periodic task
 452   if (PeriodicTask::num_tasks() > 0)
 453     WatcherThread::stop();
 454 
 455   // Print statistics gathered (profiling ...)
 456   if (Arguments::has_profile()) {
 457     FlatProfiler::disengage();
 458     FlatProfiler::print(10);
 459   }
 460 
 461   // shut down the StatSampler task
 462   StatSampler::disengage();
 463   StatSampler::destroy();
 464 
 465 #ifndef SERIALGC
 466   // stop CMS threads
 467   if (UseConcMarkSweepGC) {
 468     ConcurrentMarkSweepThread::stop();
 469   }
 470 #endif // SERIALGC
 471 
 472   // Print GC/heap related information.
 473   if (PrintGCDetails) {
 474     Universe::print();
 475     AdaptiveSizePolicyOutput(0);
 476   }
 477 
 478 
 479   if (Arguments::has_alloc_profile()) {
 480     HandleMark hm;
 481     // Do one last collection to enumerate all the objects
 482     // allocated since the last one.
 483     Universe::heap()->collect(GCCause::_allocation_profiler);
 484     AllocationProfiler::disengage();
 485     AllocationProfiler::print(0);
 486   }
 487 
 488   if (PrintBytecodeHistogram) {
 489     BytecodeHistogram::print();
 490   }
 491 
 492   if (JvmtiExport::should_post_thread_life()) {
 493     JvmtiExport::post_thread_end(thread);
 494   }
 495   // Always call even when there are not JVMTI environments yet, since environments
 496   // may be attached late and JVMTI must track phases of VM execution
 497   JvmtiExport::post_vm_death();
 498   Threads::shutdown_vm_agents();
 499 
 500   // Terminate the signal thread
 501   // Note: we don't wait until it actually dies.
 502   os::terminate_signal_thread();
 503 
 504   print_statistics();
 505   Universe::heap()->print_tracing_info();
 506 
 507   { MutexLocker ml(BeforeExit_lock);
 508     _before_exit_status = BEFORE_EXIT_DONE;
 509     BeforeExit_lock->notify_all();
 510   }
 511 
 512   #undef BEFORE_EXIT_NOT_RUN
 513   #undef BEFORE_EXIT_RUNNING
 514   #undef BEFORE_EXIT_DONE
 515 }
 516 
 517 void vm_exit(int code) {
 518   Thread* thread = ThreadLocalStorage::thread_index() == -1 ? NULL
 519     : ThreadLocalStorage::get_thread_slow();
 520   if (thread == NULL) {
 521     // we have serious problems -- just exit
 522     vm_direct_exit(code);
 523   }
 524 
 525   if (VMThread::vm_thread() != NULL) {
 526     // Fire off a VM_Exit operation to bring VM to a safepoint and exit
 527     VM_Exit op(code);
 528     if (thread->is_Java_thread())
 529       ((JavaThread*)thread)->set_thread_state(_thread_in_vm);
 530     VMThread::execute(&op);
 531     // should never reach here; but in case something wrong with VM Thread.
 532     vm_direct_exit(code);
 533   } else {
 534     // VM thread is gone, just exit
 535     vm_direct_exit(code);
 536   }
 537   ShouldNotReachHere();
 538 }
 539 
 540 void notify_vm_shutdown() {
 541   // For now, just a dtrace probe.
 542   HS_DTRACE_PROBE(hotspot, vm__shutdown);
 543   HS_DTRACE_WORKAROUND_TAIL_CALL_BUG();
 544 }
 545 
 546 void vm_direct_exit(int code) {
 547   notify_vm_shutdown();
 548   ::exit(code);
 549 }
 550 
 551 void vm_perform_shutdown_actions() {
 552   // Warning: do not call 'exit_globals()' here. All threads are still running.
 553   // Calling 'exit_globals()' will disable thread-local-storage and cause all
 554   // kinds of assertions to trigger in debug mode.
 555   if (is_init_completed()) {
 556     Thread* thread = Thread::current();
 557     if (thread->is_Java_thread()) {
 558       // We are leaving the VM, set state to native (in case any OS exit
 559       // handlers call back to the VM)
 560       JavaThread* jt = (JavaThread*)thread;
 561       // Must always be walkable or have no last_Java_frame when in
 562       // thread_in_native
 563       jt->frame_anchor()->make_walkable(jt);
 564       jt->set_thread_state(_thread_in_native);
 565     }
 566   }
 567   notify_vm_shutdown();
 568 }
 569 
 570 void vm_shutdown()
 571 {
 572   vm_perform_shutdown_actions();
 573   os::shutdown();
 574 }
 575 
 576 void vm_abort(bool dump_core) {
 577   vm_perform_shutdown_actions();
 578   os::abort(dump_core);
 579   ShouldNotReachHere();
 580 }
 581 
 582 void vm_notify_during_shutdown(const char* error, const char* message) {
 583   if (error != NULL) {
 584     tty->print_cr("Error occurred during initialization of VM");
 585     tty->print("%s", error);
 586     if (message != NULL) {
 587       tty->print_cr(": %s", message);
 588     }
 589     else {
 590       tty->cr();
 591     }
 592   }
 593   if (ShowMessageBoxOnError && WizardMode) {
 594     fatal("Error occurred during initialization of VM");
 595   }
 596 }
 597 
 598 void vm_exit_during_initialization(Handle exception) {
 599   tty->print_cr("Error occurred during initialization of VM");
 600   // If there are exceptions on this thread it must be cleared
 601   // first and here. Any future calls to EXCEPTION_MARK requires
 602   // that no pending exceptions exist.
 603   Thread *THREAD = Thread::current();
 604   if (HAS_PENDING_EXCEPTION) {
 605     CLEAR_PENDING_EXCEPTION;
 606   }
 607   java_lang_Throwable::print(exception, tty);
 608   tty->cr();
 609   java_lang_Throwable::print_stack_trace(exception(), tty);
 610   tty->cr();
 611   vm_notify_during_shutdown(NULL, NULL);
 612 
 613   // Failure during initialization, we don't want to dump core
 614   vm_abort(false);
 615 }
 616 
 617 void vm_exit_during_initialization(symbolHandle ex, const char* message) {
 618   ResourceMark rm;
 619   vm_notify_during_shutdown(ex->as_C_string(), message);
 620 
 621   // Failure during initialization, we don't want to dump core
 622   vm_abort(false);
 623 }
 624 
 625 void vm_exit_during_initialization(const char* error, const char* message) {
 626   vm_notify_during_shutdown(error, message);
 627 
 628   // Failure during initialization, we don't want to dump core
 629   vm_abort(false);
 630 }
 631 
 632 void vm_shutdown_during_initialization(const char* error, const char* message) {
 633   vm_notify_during_shutdown(error, message);
 634   vm_shutdown();
 635 }
 636 
 637 JDK_Version JDK_Version::_current;
 638 
 639 void JDK_Version::initialize() {
 640   jdk_version_info info;
 641   assert(!_current.is_valid(), "Don't initialize twice");
 642 
 643   void *lib_handle = os::native_java_library();
 644   jdk_version_info_fn_t func = CAST_TO_FN_PTR(jdk_version_info_fn_t,
 645      os::dll_lookup(lib_handle, "JDK_GetVersionInfo0"));
 646 
 647   if (func == NULL) {
 648     // JDK older than 1.6
 649     _current._partially_initialized = true;
 650   } else {
 651     (*func)(&info, sizeof(info));
 652 
 653     int major = JDK_VERSION_MAJOR(info.jdk_version);
 654     int minor = JDK_VERSION_MINOR(info.jdk_version);
 655     int micro = JDK_VERSION_MICRO(info.jdk_version);
 656     int build = JDK_VERSION_BUILD(info.jdk_version);
 657     if (major == 1 && minor > 4) {
 658       // We represent "1.5.0" as "5.0", but 1.4.2 as itself.
 659       major = minor;
 660       minor = micro;
 661       micro = 0;
 662     }
 663     _current = JDK_Version(major, minor, micro, info.update_version,
 664                            info.special_update_version, build,
 665                            info.thread_park_blocker == 1);
 666   }
 667 }
 668 
 669 void JDK_Version::fully_initialize(
 670     uint8_t major, uint8_t minor, uint8_t micro, uint8_t update) {
 671   // This is only called when current is less than 1.6 and we've gotten
 672   // far enough in the initialization to determine the exact version.
 673   assert(major < 6, "not needed for JDK version >= 6");
 674   assert(is_partially_initialized(), "must not initialize");
 675   if (major < 5) {
 676     // JDK verison sequence: 1.2.x, 1.3.x, 1.4.x, 5.0.x, 6.0.x, etc.
 677     micro = minor;
 678     minor = major;
 679     major = 1;
 680   }
 681   _current = JDK_Version(major, minor, micro, update);
 682 }
 683 
 684 void JDK_Version_init() {
 685   JDK_Version::initialize();
 686 }
 687 
 688 static int64_t encode_jdk_version(const JDK_Version& v) {
 689   return
 690     ((int64_t)v.major_version()          << (BitsPerByte * 5)) |
 691     ((int64_t)v.minor_version()          << (BitsPerByte * 4)) |
 692     ((int64_t)v.micro_version()          << (BitsPerByte * 3)) |
 693     ((int64_t)v.update_version()         << (BitsPerByte * 2)) |
 694     ((int64_t)v.special_update_version() << (BitsPerByte * 1)) |
 695     ((int64_t)v.build_number()           << (BitsPerByte * 0));
 696 }
 697 
 698 int JDK_Version::compare(const JDK_Version& other) const {
 699   assert(is_valid() && other.is_valid(), "Invalid version (uninitialized?)");
 700   if (!is_partially_initialized() && other.is_partially_initialized()) {
 701     return -(other.compare(*this)); // flip the comparators
 702   }
 703   assert(!other.is_partially_initialized(), "Not initialized yet");
 704   if (is_partially_initialized()) {
 705     assert(other.major_version() >= 6,
 706            "Invalid JDK version comparison during initialization");
 707     return -1;
 708   } else {
 709     uint64_t e = encode_jdk_version(*this);
 710     uint64_t o = encode_jdk_version(other);
 711     return (e > o) ? 1 : ((e == o) ? 0 : -1);
 712   }
 713 }
 714 
 715 void JDK_Version::to_string(char* buffer, size_t buflen) const {
 716   size_t index = 0;
 717   if (!is_valid()) {
 718     jio_snprintf(buffer, buflen, "%s", "(uninitialized)");
 719   } else if (is_partially_initialized()) {
 720     jio_snprintf(buffer, buflen, "%s", "(uninitialized) pre-1.6.0");
 721   } else {
 722     index += jio_snprintf(
 723         &buffer[index], buflen - index, "%d.%d", _major, _minor);
 724     if (_micro > 0) {
 725       index += jio_snprintf(&buffer[index], buflen - index, ".%d", _micro);
 726     }
 727     if (_update > 0) {
 728       index += jio_snprintf(&buffer[index], buflen - index, "_%02d", _update);
 729     }
 730     if (_special > 0) {
 731       index += jio_snprintf(&buffer[index], buflen - index, "%c", _special);
 732     }
 733     if (_build > 0) {
 734       index += jio_snprintf(&buffer[index], buflen - index, "-b%02d", _build);
 735     }
 736   }
 737 }