1 /*
   2  * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2021, Azul Systems, Inc. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #ifndef SHARE_RUNTIME_JAVATHREAD_HPP
  27 #define SHARE_RUNTIME_JAVATHREAD_HPP
  28 
  29 #include "jni.h"
  30 #include "memory/allocation.hpp"
  31 #include "oops/oop.hpp"
  32 #include "oops/oopHandle.hpp"
  33 #include "runtime/frame.hpp"
  34 #include "runtime/globals.hpp"
  35 #include "runtime/handshake.hpp"
  36 #include "runtime/javaFrameAnchor.hpp"
  37 #include "runtime/lockStack.hpp"
  38 #include "runtime/park.hpp"
  39 #include "runtime/safepointMechanism.hpp"
  40 #include "runtime/stackWatermarkSet.hpp"
  41 #include "runtime/stackOverflow.hpp"
  42 #include "runtime/thread.hpp"
  43 #include "runtime/threadHeapSampler.hpp"
  44 #include "runtime/threadStatisticalInfo.hpp"
  45 #include "utilities/exceptions.hpp"
  46 #include "utilities/globalDefinitions.hpp"
  47 #include "utilities/macros.hpp"
  48 #if INCLUDE_JFR
  49 #include "jfr/support/jfrThreadExtension.hpp"
  50 #endif
  51 
  52 class AsyncExceptionHandshake;
  53 class ContinuationEntry;
  54 class DeoptResourceMark;
  55 class JNIHandleBlock;
  56 class JVMCIRuntime;
  57 
  58 class JvmtiDeferredUpdates;
  59 class JvmtiSampledObjectAllocEventCollector;
  60 class JvmtiThreadState;
  61 
  62 class Metadata;
  63 class OopHandleList;
  64 class OopStorage;
  65 class OSThread;
  66 
  67 class ThreadsList;
  68 class ThreadSafepointState;
  69 class ThreadStatistics;
  70 
  71 class vframeArray;
  72 class vframe;
  73 class javaVFrame;
  74 
  75 class JavaThread;
  76 typedef void (*ThreadFunction)(JavaThread*, TRAPS);
  77 
  78 class JavaThread: public Thread {
  79   friend class VMStructs;
  80   friend class JVMCIVMStructs;
  81   friend class WhiteBox;
  82   friend class ThreadsSMRSupport; // to access _threadObj for exiting_threads_oops_do
  83   friend class HandshakeState;
  84   friend class Continuation;
  85   friend class Threads;
  86   friend class ServiceThread; // for deferred OopHandle release access
  87  private:
  88   bool           _on_thread_list;                // Is set when this JavaThread is added to the Threads list
  89 
  90   // All references to Java objects managed via OopHandles. These
  91   // have to be released by the ServiceThread after the JavaThread has
  92   // terminated - see add_oop_handles_for_release().
  93   OopHandle      _threadObj;                     // The Java level thread object
  94   OopHandle      _vthread; // the value returned by Thread.currentThread(): the virtual thread, if mounted, otherwise _threadObj
  95   OopHandle      _jvmti_vthread;
  96   OopHandle      _scopedValueCache;
  97 
  98   static OopStorage* _thread_oop_storage;
  99 
 100 #ifdef ASSERT
 101  private:
 102   int _java_call_counter;
 103 
 104  public:
 105   int  java_call_counter()                       { return _java_call_counter; }
 106   void inc_java_call_counter()                   { _java_call_counter++; }
 107   void dec_java_call_counter() {
 108     assert(_java_call_counter > 0, "Invalid nesting of JavaCallWrapper");
 109     _java_call_counter--;
 110   }
 111  private:  // restore original namespace restriction
 112 #endif  // ifdef ASSERT
 113 
 114   JavaFrameAnchor _anchor;                       // Encapsulation of current java frame and it state
 115 
 116   ThreadFunction _entry_point;
 117 
 118   JNIEnv        _jni_environment;
 119 
 120   // Deopt support
 121   DeoptResourceMark*  _deopt_mark;               // Holds special ResourceMark for deoptimization
 122 
 123   CompiledMethod*       _deopt_nmethod;         // CompiledMethod that is currently being deoptimized
 124   vframeArray*  _vframe_array_head;              // Holds the heap of the active vframeArrays
 125   vframeArray*  _vframe_array_last;              // Holds last vFrameArray we popped
 126   // Holds updates by JVMTI agents for compiled frames that cannot be performed immediately. They
 127   // will be carried out as soon as possible which, in most cases, is just before deoptimization of
 128   // the frame, when control returns to it.
 129   JvmtiDeferredUpdates* _jvmti_deferred_updates;
 130 
 131   // Handshake value for fixing 6243940. We need a place for the i2c
 132   // adapter to store the callee Method*. This value is NEVER live
 133   // across a gc point so it does NOT have to be gc'd
 134   // The handshake is open ended since we can't be certain that it will
 135   // be nulled. This is because we rarely ever see the race and end up
 136   // in handle_wrong_method which is the backend of the handshake. See
 137   // code in i2c adapters and handle_wrong_method.
 138 
 139   Method*       _callee_target;
 140 
 141   // Used to pass back results to the interpreter or generated code running Java code.
 142   oop           _vm_result;    // oop result is GC-preserved
 143   Metadata*     _vm_result_2;  // non-oop result
 144 
 145   // See ReduceInitialCardMarks: this holds the precise space interval of
 146   // the most recent slow path allocation for which compiled code has
 147   // elided card-marks for performance along the fast-path.
 148   MemRegion     _deferred_card_mark;
 149 
 150   ObjectMonitor* volatile _current_pending_monitor;     // ObjectMonitor this thread is waiting to lock
 151   bool           _current_pending_monitor_is_from_java; // locking is from Java code
 152   ObjectMonitor* volatile _current_waiting_monitor;     // ObjectMonitor on which this thread called Object.wait()
 153 
 154   // Active_handles points to a block of handles
 155   JNIHandleBlock* _active_handles;
 156 
 157   // One-element thread local free list
 158   JNIHandleBlock* _free_handle_block;
 159 
 160  public:
 161   volatile intptr_t _Stalled;
 162 
 163   // For tracking the heavyweight monitor the thread is pending on.
 164   ObjectMonitor* current_pending_monitor() {
 165     // Use Atomic::load() to prevent data race between concurrent modification and
 166     // concurrent readers, e.g. ThreadService::get_current_contended_monitor().
 167     // Especially, reloading pointer from thread after null check must be prevented.
 168     return Atomic::load(&_current_pending_monitor);
 169   }
 170   void set_current_pending_monitor(ObjectMonitor* monitor) {
 171     Atomic::store(&_current_pending_monitor, monitor);
 172   }
 173   void set_current_pending_monitor_is_from_java(bool from_java) {
 174     _current_pending_monitor_is_from_java = from_java;
 175   }
 176   bool current_pending_monitor_is_from_java() {
 177     return _current_pending_monitor_is_from_java;
 178   }
 179   ObjectMonitor* current_waiting_monitor() {
 180     // See the comment in current_pending_monitor() above.
 181     return Atomic::load(&_current_waiting_monitor);
 182   }
 183   void set_current_waiting_monitor(ObjectMonitor* monitor) {
 184     Atomic::store(&_current_waiting_monitor, monitor);
 185   }
 186 
 187   // JNI handle support
 188   JNIHandleBlock* active_handles() const         { return _active_handles; }
 189   void set_active_handles(JNIHandleBlock* block) { _active_handles = block; }
 190   JNIHandleBlock* free_handle_block() const      { return _free_handle_block; }
 191   void set_free_handle_block(JNIHandleBlock* block) { _free_handle_block = block; }
 192 
 193   void push_jni_handle_block();
 194   void pop_jni_handle_block();
 195 
 196  private:
 197   MonitorChunk* _monitor_chunks;              // Contains the off stack monitors
 198                                               // allocated during deoptimization
 199                                               // and by JNI_MonitorEnter/Exit
 200 
 201   enum SuspendFlags {
 202     // NOTE: avoid using the sign-bit as cc generates different test code
 203     //       when the sign-bit is used, and sometimes incorrectly - see CR 6398077
 204     _trace_flag             = 0x00000004U, // call tracing backend
 205     _obj_deopt              = 0x00000008U  // suspend for object reallocation and relocking for JVMTI agent
 206   };
 207 
 208   // various suspension related flags - atomically updated
 209   volatile uint32_t _suspend_flags;
 210 
 211   inline void set_suspend_flag(SuspendFlags f);
 212   inline void clear_suspend_flag(SuspendFlags f);
 213 
 214  public:
 215   inline void set_trace_flag();
 216   inline void clear_trace_flag();
 217   inline void set_obj_deopt_flag();
 218   inline void clear_obj_deopt_flag();
 219   bool is_trace_suspend()      { return (_suspend_flags & _trace_flag) != 0; }
 220   bool is_obj_deopt_suspend()  { return (_suspend_flags & _obj_deopt) != 0; }
 221 
 222   // Asynchronous exception support
 223  private:
 224   friend class InstallAsyncExceptionHandshake;
 225   friend class AsyncExceptionHandshake;
 226   friend class HandshakeState;
 227 
 228   void handle_async_exception(oop java_throwable);
 229  public:
 230   void install_async_exception(AsyncExceptionHandshake* aec = nullptr);
 231   bool has_async_exception_condition();
 232   inline void set_pending_unsafe_access_error();
 233   static void send_async_exception(JavaThread* jt, oop java_throwable);
 234 
 235   class NoAsyncExceptionDeliveryMark : public StackObj {
 236     friend JavaThread;
 237     JavaThread *_target;
 238     inline NoAsyncExceptionDeliveryMark(JavaThread *t);
 239     inline ~NoAsyncExceptionDeliveryMark();
 240   };
 241 
 242   // Safepoint support
 243  public:                                                        // Expose _thread_state for SafeFetchInt()
 244   volatile JavaThreadState _thread_state;
 245  private:
 246   SafepointMechanism::ThreadData _poll_data;
 247   ThreadSafepointState*          _safepoint_state;              // Holds information about a thread during a safepoint
 248   address                        _saved_exception_pc;           // Saved pc of instruction where last implicit exception happened
 249   NOT_PRODUCT(bool               _requires_cross_modify_fence;) // State used by VerifyCrossModifyFence
 250 #ifdef ASSERT
 251   // Debug support for checking if code allows safepoints or not.
 252   // Safepoints in the VM can happen because of allocation, invoking a VM operation, or blocking on
 253   // mutex, or blocking on an object synchronizer (Java locking).
 254   // If _no_safepoint_count is non-zero, then an assertion failure will happen in any of
 255   // the above cases. The class NoSafepointVerifier is used to set this counter.
 256   int _no_safepoint_count;                             // If 0, thread allow a safepoint to happen
 257 
 258  public:
 259   void inc_no_safepoint_count() { _no_safepoint_count++; }
 260   void dec_no_safepoint_count() { _no_safepoint_count--; }
 261   bool is_in_no_safepoint_scope() { return _no_safepoint_count > 0; }
 262 #endif // ASSERT
 263  public:
 264   // These functions check conditions before possibly going to a safepoint.
 265   // including NoSafepointVerifier.
 266   void check_for_valid_safepoint_state() NOT_DEBUG_RETURN;
 267   void check_possible_safepoint()        NOT_DEBUG_RETURN;
 268 
 269 #ifdef ASSERT
 270  private:
 271   volatile uint64_t _visited_for_critical_count;
 272 
 273  public:
 274   void set_visited_for_critical_count(uint64_t safepoint_id) {
 275     assert(_visited_for_critical_count == 0, "Must be reset before set");
 276     assert((safepoint_id & 0x1) == 1, "Must be odd");
 277     _visited_for_critical_count = safepoint_id;
 278   }
 279   void reset_visited_for_critical_count(uint64_t safepoint_id) {
 280     assert(_visited_for_critical_count == safepoint_id, "Was not visited");
 281     _visited_for_critical_count = 0;
 282   }
 283   bool was_visited_for_critical_count(uint64_t safepoint_id) const {
 284     return _visited_for_critical_count == safepoint_id;
 285   }
 286 #endif // ASSERT
 287 
 288   // JavaThread termination support
 289  public:
 290   enum TerminatedTypes {
 291     _not_terminated = 0xDEAD - 3,
 292     _thread_exiting,                             // JavaThread::exit() has been called for this thread
 293     _thread_gc_barrier_detached,                 // thread's GC barrier has been detached
 294     _thread_terminated,                          // JavaThread is removed from thread list
 295     _vm_exited                                   // JavaThread is still executing native code, but VM is terminated
 296                                                  // only VM_Exit can set _vm_exited
 297   };
 298 
 299  private:
 300   // In general a JavaThread's _terminated field transitions as follows:
 301   //
 302   //   _not_terminated => _thread_exiting => _thread_gc_barrier_detached => _thread_terminated
 303   //
 304   // _vm_exited is a special value to cover the case of a JavaThread
 305   // executing native code after the VM itself is terminated.
 306   //
 307   // A JavaThread that fails to JNI attach has these _terminated field transitions:
 308   //   _not_terminated => _thread_terminated
 309   //
 310   volatile TerminatedTypes _terminated;
 311 
 312   jint                  _in_deopt_handler;       // count of deoptimization
 313                                                  // handlers thread is in
 314   volatile bool         _doing_unsafe_access;    // Thread may fault due to unsafe access
 315   bool                  _do_not_unlock_if_synchronized;  // Do not unlock the receiver of a synchronized method (since it was
 316                                                          // never locked) when throwing an exception. Used by interpreter only.
 317 #if INCLUDE_JVMTI
 318   volatile bool         _carrier_thread_suspended;       // Carrier thread is externally suspended
 319   bool                  _is_in_VTMS_transition;          // thread is in virtual thread mount state transition
 320   bool                  _is_in_tmp_VTMS_transition;      // thread is in temporary virtual thread mount state transition
 321   bool                  _is_disable_suspend;             // JVMTI suspend is temporarily disabled; used on current thread only
 322 #ifdef ASSERT
 323   bool                  _is_VTMS_transition_disabler;    // thread currently disabled VTMS transitions
 324 #endif
 325 #endif
 326 
 327   // JNI attach states:
 328   enum JNIAttachStates {
 329     _not_attaching_via_jni = 1,  // thread is not attaching via JNI
 330     _attaching_via_jni,          // thread is attaching via JNI
 331     _attached_via_jni            // thread has attached via JNI
 332   };
 333 
 334   // A regular JavaThread's _jni_attach_state is _not_attaching_via_jni.
 335   // A native thread that is attaching via JNI starts with a value
 336   // of _attaching_via_jni and transitions to _attached_via_jni.
 337   volatile JNIAttachStates _jni_attach_state;
 338 
 339 
 340 #if INCLUDE_JVMCI
 341   // The _pending_* fields below are used to communicate extra information
 342   // from an uncommon trap in JVMCI compiled code to the uncommon trap handler.
 343 
 344   // Communicates the DeoptReason and DeoptAction of the uncommon trap
 345   int       _pending_deoptimization;
 346 
 347   // Specifies whether the uncommon trap is to bci 0 of a synchronized method
 348   // before the monitor has been acquired.
 349   bool      _pending_monitorenter;
 350 
 351   // Specifies if the DeoptReason for the last uncommon trap was Reason_transfer_to_interpreter
 352   bool      _pending_transfer_to_interpreter;
 353 
 354   // True if in a runtime call from compiled code that will deoptimize
 355   // and re-execute a failed heap allocation in the interpreter.
 356   bool      _in_retryable_allocation;
 357 
 358   // An id of a speculation that JVMCI compiled code can use to further describe and
 359   // uniquely identify the speculative optimization guarded by an uncommon trap.
 360   // See JVMCINMethodData::SPECULATION_LENGTH_BITS for further details.
 361   jlong     _pending_failed_speculation;
 362 
 363   // These fields are mutually exclusive in terms of live ranges.
 364   union {
 365     // Communicates the pc at which the most recent implicit exception occurred
 366     // from the signal handler to a deoptimization stub.
 367     address   _implicit_exception_pc;
 368 
 369     // Communicates an alternative call target to an i2c stub from a JavaCall .
 370     address   _alternate_call_target;
 371   } _jvmci;
 372 
 373   // The JVMCIRuntime in a JVMCI shared library
 374   JVMCIRuntime* _libjvmci_runtime;
 375 
 376   // Support for high precision, thread sensitive counters in JVMCI compiled code.
 377   jlong*    _jvmci_counters;
 378 
 379   // Fast thread locals for use by JVMCI
 380   jlong      _jvmci_reserved0;
 381   jlong      _jvmci_reserved1;
 382   oop        _jvmci_reserved_oop0;
 383 
 384  public:
 385   static jlong* _jvmci_old_thread_counters;
 386   static void collect_counters(jlong* array, int length);
 387 
 388   bool resize_counters(int current_size, int new_size);
 389 
 390   static bool resize_all_jvmci_counters(int new_size);
 391 
 392   void set_jvmci_reserved_oop0(oop value) {
 393     _jvmci_reserved_oop0 = value;
 394   }
 395 
 396   oop get_jvmci_reserved_oop0() {
 397     return _jvmci_reserved_oop0;
 398   }
 399 
 400   void set_jvmci_reserved0(jlong value) {
 401     _jvmci_reserved0 = value;
 402   }
 403 
 404   jlong get_jvmci_reserved0() {
 405     return _jvmci_reserved0;
 406   }
 407 
 408   void set_jvmci_reserved1(jlong value) {
 409     _jvmci_reserved1 = value;
 410   }
 411 
 412   jlong get_jvmci_reserved1() {
 413     return _jvmci_reserved1;
 414   }
 415 
 416  private:
 417 #endif // INCLUDE_JVMCI
 418 
 419   StackOverflow    _stack_overflow_state;
 420 
 421   void pretouch_stack();
 422 
 423   // Compiler exception handling (NOTE: The _exception_oop is *NOT* the same as _pending_exception. It is
 424   // used to temp. parsing values into and out of the runtime system during exception handling for compiled
 425   // code)
 426   volatile oop     _exception_oop;               // Exception thrown in compiled code
 427   volatile address _exception_pc;                // PC where exception happened
 428   volatile address _exception_handler_pc;        // PC for handler of exception
 429   volatile int     _is_method_handle_return;     // true (== 1) if the current exception PC is a MethodHandle call site.
 430 
 431  private:
 432   // support for JNI critical regions
 433   jint    _jni_active_critical;                  // count of entries into JNI critical region
 434 
 435   // Checked JNI: function name requires exception check
 436   char* _pending_jni_exception_check_fn;
 437 
 438   // For deadlock detection.
 439   int _depth_first_number;
 440 
 441   // JVMTI PopFrame support
 442   // This is set to popframe_pending to signal that top Java frame should be popped immediately
 443   int _popframe_condition;
 444 
 445   // If reallocation of scalar replaced objects fails, we throw OOM
 446   // and during exception propagation, pop the top
 447   // _frames_to_pop_failed_realloc frames, the ones that reference
 448   // failed reallocations.
 449   int _frames_to_pop_failed_realloc;
 450 
 451   ContinuationEntry* _cont_entry;
 452   intptr_t* _cont_fastpath; // the sp of the oldest known interpreted/call_stub frame inside the
 453                             // continuation that we know about
 454   int _cont_fastpath_thread_state; // whether global thread state allows continuation fastpath (JVMTI)
 455 
 456   // It's signed for error detection.
 457   intx _held_monitor_count;  // used by continuations for fast lock detection
 458   intx _jni_monitor_count;
 459 
 460   bool _can_call_java;
 461 
 462 private:
 463 
 464   friend class VMThread;
 465   friend class ThreadWaitTransition;
 466   friend class VM_Exit;
 467 
 468   // Stack watermark barriers.
 469   StackWatermarks _stack_watermarks;
 470 
 471  public:
 472   inline StackWatermarks* stack_watermarks() { return &_stack_watermarks; }
 473 
 474  public:
 475   // Constructor
 476   JavaThread();                            // delegating constructor
 477   JavaThread(bool is_attaching_via_jni);   // for main thread and JNI attached threads
 478   JavaThread(ThreadFunction entry_point, size_t stack_size = 0);
 479   ~JavaThread();
 480 
 481 #ifdef ASSERT
 482   // verify this JavaThread hasn't be published in the Threads::list yet
 483   void verify_not_published();
 484 #endif // ASSERT
 485 
 486   StackOverflow* stack_overflow_state() { return &_stack_overflow_state; }
 487 
 488   //JNI functiontable getter/setter for JVMTI jni function table interception API.
 489   void set_jni_functions(struct JNINativeInterface_* functionTable) {
 490     _jni_environment.functions = functionTable;
 491   }
 492   struct JNINativeInterface_* get_jni_functions() {
 493     return (struct JNINativeInterface_ *)_jni_environment.functions;
 494   }
 495 
 496   // This function is called at thread creation to allow
 497   // platform specific thread variables to be initialized.
 498   void cache_global_variables();
 499 
 500   // Executes Shutdown.shutdown()
 501   void invoke_shutdown_hooks();
 502 
 503   // Cleanup on thread exit
 504   enum ExitType {
 505     normal_exit,
 506     jni_detach
 507   };
 508   void exit(bool destroy_vm, ExitType exit_type = normal_exit);
 509 
 510   void cleanup_failed_attach_current_thread(bool is_daemon);
 511 
 512   class NoJavaCodeMark : public StackObj {
 513     friend JavaThread;
 514     JavaThread* _target;
 515     bool _orig;
 516    public:
 517     NoJavaCodeMark(JavaThread* t) : _target(t), _orig(t->_can_call_java) {
 518       _target->_can_call_java = false;
 519     }
 520     ~NoJavaCodeMark() {
 521       _target->_can_call_java = _orig;
 522     }
 523   };
 524 
 525   // Testers
 526   virtual bool is_Java_thread() const            { return true;  }
 527   virtual bool can_call_java() const             { return _can_call_java; }
 528 
 529   virtual bool is_active_Java_thread() const;
 530 
 531   // Thread oop. threadObj() can be null for initial JavaThread
 532   // (or for threads attached via JNI)
 533   oop threadObj() const;
 534   void set_threadOopHandles(oop p);
 535   oop vthread() const;
 536   void set_vthread(oop p);
 537   oop scopedValueCache() const;
 538   void set_scopedValueCache(oop p);
 539   void clear_scopedValueBindings();
 540   oop jvmti_vthread() const;
 541   void set_jvmti_vthread(oop p);
 542 
 543   // Prepare thread and add to priority queue.  If a priority is
 544   // not specified, use the priority of the thread object. Threads_lock
 545   // must be held while this function is called.
 546   void prepare(jobject jni_thread, ThreadPriority prio=NoPriority);
 547 
 548   void set_saved_exception_pc(address pc)        { _saved_exception_pc = pc; }
 549   address saved_exception_pc()                   { return _saved_exception_pc; }
 550 
 551   ThreadFunction entry_point() const             { return _entry_point; }
 552 
 553   // Allocates a new Java level thread object for this thread. thread_name may be null.
 554   void allocate_threadObj(Handle thread_group, const char* thread_name, bool daemon, TRAPS);
 555 
 556   // Last frame anchor routines
 557 
 558   JavaFrameAnchor* frame_anchor(void)            { return &_anchor; }
 559 
 560   // last_Java_sp
 561   bool has_last_Java_frame() const               { return _anchor.has_last_Java_frame(); }
 562   intptr_t* last_Java_sp() const                 { return _anchor.last_Java_sp(); }
 563 
 564   // last_Java_pc
 565 
 566   address last_Java_pc(void)                     { return _anchor.last_Java_pc(); }
 567 
 568   // Safepoint support
 569   inline JavaThreadState thread_state() const;
 570   inline void set_thread_state(JavaThreadState s);
 571   inline void set_thread_state_fence(JavaThreadState s);  // fence after setting thread state
 572   inline ThreadSafepointState* safepoint_state() const;
 573   inline void set_safepoint_state(ThreadSafepointState* state);
 574   inline bool is_at_poll_safepoint();
 575 
 576   // JavaThread termination and lifecycle support:
 577   void smr_delete();
 578   bool on_thread_list() const { return _on_thread_list; }
 579   void set_on_thread_list() { _on_thread_list = true; }
 580 
 581   // thread has called JavaThread::exit(), thread's GC barrier is detached
 582   // or thread is terminated
 583   bool is_exiting() const;
 584   // thread's GC barrier is NOT detached and thread is NOT terminated
 585   bool is_oop_safe() const;
 586   // thread is terminated (no longer on the threads list); the thread must
 587   // be protected by a ThreadsListHandle to avoid potential crashes.
 588   bool check_is_terminated(TerminatedTypes l_terminated) const {
 589     return l_terminated == _thread_terminated || l_terminated == _vm_exited;
 590   }
 591   bool is_terminated() const;
 592   void set_terminated(TerminatedTypes t);
 593 
 594   void block_if_vm_exited();
 595 
 596   bool doing_unsafe_access()                     { return _doing_unsafe_access; }
 597   void set_doing_unsafe_access(bool val)         { _doing_unsafe_access = val; }
 598 
 599   bool do_not_unlock_if_synchronized()             { return _do_not_unlock_if_synchronized; }
 600   void set_do_not_unlock_if_synchronized(bool val) { _do_not_unlock_if_synchronized = val; }
 601 
 602   SafepointMechanism::ThreadData* poll_data() { return &_poll_data; }
 603 
 604   void set_requires_cross_modify_fence(bool val) PRODUCT_RETURN NOT_PRODUCT({ _requires_cross_modify_fence = val; })
 605 
 606   // Continuation support
 607   ContinuationEntry* last_continuation() const { return _cont_entry; }
 608   void set_cont_fastpath(intptr_t* x)          { _cont_fastpath = x; }
 609   void push_cont_fastpath(intptr_t* sp)        { if (sp > _cont_fastpath) _cont_fastpath = sp; }
 610   void set_cont_fastpath_thread_state(bool x)  { _cont_fastpath_thread_state = (int)x; }
 611   intptr_t* raw_cont_fastpath() const          { return _cont_fastpath; }
 612   bool cont_fastpath() const                   { return _cont_fastpath == nullptr && _cont_fastpath_thread_state != 0; }
 613   bool cont_fastpath_thread_state() const      { return _cont_fastpath_thread_state != 0; }
 614 
 615   void inc_held_monitor_count(intx i = 1, bool jni = false);
 616   void dec_held_monitor_count(intx i = 1, bool jni = false);
 617 
 618   intx held_monitor_count() { return _held_monitor_count; }
 619   intx jni_monitor_count()  { return _jni_monitor_count;  }
 620   void clear_jni_monitor_count() { _jni_monitor_count = 0;   }
 621 
 622   inline bool is_vthread_mounted() const;
 623   inline const ContinuationEntry* vthread_continuation() const;
 624 
 625  private:
 626   DEBUG_ONLY(void verify_frame_info();)
 627 
 628   // Support for thread handshake operations
 629   HandshakeState _handshake;
 630  public:
 631   HandshakeState* handshake_state() { return &_handshake; }
 632 
 633   // A JavaThread can always safely operate on it self and other threads
 634   // can do it safely if they are the active handshaker.
 635   bool is_handshake_safe_for(Thread* th) const {
 636     return _handshake.active_handshaker() == th || this == th;
 637   }
 638 
 639   // Suspend/resume support for JavaThread
 640   // higher-level suspension/resume logic called by the public APIs
 641   bool java_suspend();
 642   bool java_resume();
 643   bool is_suspended()     { return _handshake.is_suspended(); }
 644 
 645   // Check for async exception in addition to safepoint.
 646   static void check_special_condition_for_native_trans(JavaThread *thread);
 647 
 648   // Synchronize with another thread that is deoptimizing objects of the
 649   // current thread, i.e. reverts optimizations based on escape analysis.
 650   void wait_for_object_deoptimization();
 651 
 652 #if INCLUDE_JVMTI
 653   inline void set_carrier_thread_suspended();
 654   inline void clear_carrier_thread_suspended();
 655 
 656   bool is_carrier_thread_suspended() const {
 657     return _carrier_thread_suspended;
 658   }
 659 
 660   bool is_in_VTMS_transition() const             { return _is_in_VTMS_transition; }
 661   bool is_in_tmp_VTMS_transition() const         { return _is_in_tmp_VTMS_transition; }
 662   bool is_in_any_VTMS_transition() const         { return _is_in_VTMS_transition || _is_in_tmp_VTMS_transition; }
 663 
 664   void set_is_in_VTMS_transition(bool val);
 665   void toggle_is_in_tmp_VTMS_transition()        { _is_in_tmp_VTMS_transition = !_is_in_tmp_VTMS_transition; };
 666 
 667   bool is_disable_suspend() const                { return _is_disable_suspend; }
 668   void toggle_is_disable_suspend()               { _is_disable_suspend = !_is_disable_suspend; };
 669 
 670 #ifdef ASSERT
 671   bool is_VTMS_transition_disabler() const       { return _is_VTMS_transition_disabler; }
 672   void set_is_VTMS_transition_disabler(bool val);
 673 #endif
 674 #endif
 675 
 676   // Support for object deoptimization and JFR suspension
 677   void handle_special_runtime_exit_condition();
 678   bool has_special_runtime_exit_condition() {
 679     return (_suspend_flags & (_obj_deopt JFR_ONLY(| _trace_flag))) != 0;
 680   }
 681 
 682   // Fast-locking support
 683   bool is_lock_owned(address adr) const;
 684 
 685   // Accessors for vframe array top
 686   // The linked list of vframe arrays are sorted on sp. This means when we
 687   // unpack the head must contain the vframe array to unpack.
 688   void set_vframe_array_head(vframeArray* value) { _vframe_array_head = value; }
 689   vframeArray* vframe_array_head() const         { return _vframe_array_head;  }
 690 
 691   // Side structure for deferring update of java frame locals until deopt occurs
 692   JvmtiDeferredUpdates* deferred_updates() const      { return _jvmti_deferred_updates; }
 693   void set_deferred_updates(JvmtiDeferredUpdates* du) { _jvmti_deferred_updates = du; }
 694 
 695   // These only really exist to make debugging deopt problems simpler
 696 
 697   void set_vframe_array_last(vframeArray* value) { _vframe_array_last = value; }
 698   vframeArray* vframe_array_last() const         { return _vframe_array_last;  }
 699 
 700   // The special resourceMark used during deoptimization
 701 
 702   void set_deopt_mark(DeoptResourceMark* value)  { _deopt_mark = value; }
 703   DeoptResourceMark* deopt_mark(void)            { return _deopt_mark; }
 704 
 705   void set_deopt_compiled_method(CompiledMethod* nm)  { _deopt_nmethod = nm; }
 706   CompiledMethod* deopt_compiled_method()        { return _deopt_nmethod; }
 707 
 708   Method*    callee_target() const               { return _callee_target; }
 709   void set_callee_target  (Method* x)            { _callee_target   = x; }
 710 
 711   // Oop results of vm runtime calls
 712   oop  vm_result() const                         { return _vm_result; }
 713   void set_vm_result  (oop x)                    { _vm_result   = x; }
 714 
 715   void set_vm_result_2  (Metadata* x)            { _vm_result_2   = x; }
 716 
 717   MemRegion deferred_card_mark() const           { return _deferred_card_mark; }
 718   void set_deferred_card_mark(MemRegion mr)      { _deferred_card_mark = mr;   }
 719 
 720 #if INCLUDE_JVMCI
 721   jlong pending_failed_speculation() const        { return _pending_failed_speculation; }
 722   void set_pending_monitorenter(bool b)           { _pending_monitorenter = b; }
 723   void set_pending_deoptimization(int reason)     { _pending_deoptimization = reason; }
 724   void set_pending_failed_speculation(jlong failed_speculation) { _pending_failed_speculation = failed_speculation; }
 725   void set_pending_transfer_to_interpreter(bool b) { _pending_transfer_to_interpreter = b; }
 726   void set_jvmci_alternate_call_target(address a) { assert(_jvmci._alternate_call_target == nullptr, "must be"); _jvmci._alternate_call_target = a; }
 727   void set_jvmci_implicit_exception_pc(address a) { assert(_jvmci._implicit_exception_pc == nullptr, "must be"); _jvmci._implicit_exception_pc = a; }
 728 
 729   virtual bool in_retryable_allocation() const    { return _in_retryable_allocation; }
 730   void set_in_retryable_allocation(bool b)        { _in_retryable_allocation = b; }
 731 
 732   JVMCIRuntime* libjvmci_runtime() const          { return _libjvmci_runtime; }
 733   void set_libjvmci_runtime(JVMCIRuntime* rt) {
 734     assert((_libjvmci_runtime == nullptr && rt != nullptr) || (_libjvmci_runtime != nullptr && rt == nullptr), "must be");
 735     _libjvmci_runtime = rt;
 736   }
 737 #endif // INCLUDE_JVMCI
 738 
 739   // Exception handling for compiled methods
 740   oop      exception_oop() const;
 741   address  exception_pc() const                  { return _exception_pc; }
 742 
 743   void set_exception_oop(oop o);
 744   void set_exception_pc(address a)               { _exception_pc = a; }
 745   void set_exception_handler_pc(address a)       { _exception_handler_pc = a; }
 746   void set_is_method_handle_return(bool value)   { _is_method_handle_return = value ? 1 : 0; }
 747 
 748   void clear_exception_oop_and_pc() {
 749     set_exception_oop(nullptr);
 750     set_exception_pc(nullptr);
 751   }
 752 
 753   // Check if address is in the usable part of the stack (excludes protected
 754   // guard pages). Can be applied to any thread and is an approximation for
 755   // using is_in_live_stack when the query has to happen from another thread.
 756   bool is_in_usable_stack(address adr) const {
 757     return is_in_stack_range_incl(adr, _stack_overflow_state.stack_reserved_zone_base());
 758   }
 759 
 760   // Misc. accessors/mutators
 761   static ByteSize scopedValueCache_offset()       { return byte_offset_of(JavaThread, _scopedValueCache); }
 762 
 763   // For assembly stub generation
 764   static ByteSize threadObj_offset()             { return byte_offset_of(JavaThread, _threadObj); }
 765   static ByteSize vthread_offset()               { return byte_offset_of(JavaThread, _vthread); }
 766   static ByteSize jni_environment_offset()       { return byte_offset_of(JavaThread, _jni_environment); }
 767   static ByteSize pending_jni_exception_check_fn_offset() {
 768     return byte_offset_of(JavaThread, _pending_jni_exception_check_fn);
 769   }
 770   static ByteSize last_Java_sp_offset() {
 771     return byte_offset_of(JavaThread, _anchor) + JavaFrameAnchor::last_Java_sp_offset();
 772   }
 773   static ByteSize last_Java_pc_offset() {
 774     return byte_offset_of(JavaThread, _anchor) + JavaFrameAnchor::last_Java_pc_offset();
 775   }
 776   static ByteSize frame_anchor_offset() {
 777     return byte_offset_of(JavaThread, _anchor);
 778   }
 779   static ByteSize callee_target_offset()         { return byte_offset_of(JavaThread, _callee_target); }
 780   static ByteSize vm_result_offset()             { return byte_offset_of(JavaThread, _vm_result); }
 781   static ByteSize vm_result_2_offset()           { return byte_offset_of(JavaThread, _vm_result_2); }
 782   static ByteSize thread_state_offset()          { return byte_offset_of(JavaThread, _thread_state); }
 783   static ByteSize polling_word_offset()          { return byte_offset_of(JavaThread, _poll_data) + byte_offset_of(SafepointMechanism::ThreadData, _polling_word);}
 784   static ByteSize polling_page_offset()          { return byte_offset_of(JavaThread, _poll_data) + byte_offset_of(SafepointMechanism::ThreadData, _polling_page);}
 785   static ByteSize saved_exception_pc_offset()    { return byte_offset_of(JavaThread, _saved_exception_pc); }
 786   static ByteSize osthread_offset()              { return byte_offset_of(JavaThread, _osthread); }
 787 #if INCLUDE_JVMCI
 788   static ByteSize pending_deoptimization_offset() { return byte_offset_of(JavaThread, _pending_deoptimization); }
 789   static ByteSize pending_monitorenter_offset()  { return byte_offset_of(JavaThread, _pending_monitorenter); }
 790   static ByteSize jvmci_alternate_call_target_offset() { return byte_offset_of(JavaThread, _jvmci._alternate_call_target); }
 791   static ByteSize jvmci_implicit_exception_pc_offset() { return byte_offset_of(JavaThread, _jvmci._implicit_exception_pc); }
 792   static ByteSize jvmci_counters_offset()        { return byte_offset_of(JavaThread, _jvmci_counters); }
 793 #endif // INCLUDE_JVMCI
 794   static ByteSize exception_oop_offset()         { return byte_offset_of(JavaThread, _exception_oop); }
 795   static ByteSize exception_pc_offset()          { return byte_offset_of(JavaThread, _exception_pc); }
 796   static ByteSize exception_handler_pc_offset()  { return byte_offset_of(JavaThread, _exception_handler_pc); }
 797   static ByteSize is_method_handle_return_offset() { return byte_offset_of(JavaThread, _is_method_handle_return); }
 798 
 799   static ByteSize active_handles_offset()        { return byte_offset_of(JavaThread, _active_handles); }
 800 
 801   // StackOverflow offsets
 802   static ByteSize stack_overflow_limit_offset()  {
 803     return byte_offset_of(JavaThread, _stack_overflow_state._stack_overflow_limit);
 804   }
 805   static ByteSize stack_guard_state_offset()     {
 806     return byte_offset_of(JavaThread, _stack_overflow_state._stack_guard_state);
 807   }
 808   static ByteSize reserved_stack_activation_offset() {
 809     return byte_offset_of(JavaThread, _stack_overflow_state._reserved_stack_activation);
 810   }
 811   static ByteSize shadow_zone_safe_limit()  {
 812     return byte_offset_of(JavaThread, _stack_overflow_state._shadow_zone_safe_limit);
 813   }
 814   static ByteSize shadow_zone_growth_watermark()  {
 815     return byte_offset_of(JavaThread, _stack_overflow_state._shadow_zone_growth_watermark);
 816   }
 817 
 818   static ByteSize suspend_flags_offset()         { return byte_offset_of(JavaThread, _suspend_flags); }
 819 
 820   static ByteSize do_not_unlock_if_synchronized_offset() { return byte_offset_of(JavaThread, _do_not_unlock_if_synchronized); }
 821   static ByteSize should_post_on_exceptions_flag_offset() {
 822     return byte_offset_of(JavaThread, _should_post_on_exceptions_flag);
 823   }
 824   static ByteSize doing_unsafe_access_offset() { return byte_offset_of(JavaThread, _doing_unsafe_access); }
 825   NOT_PRODUCT(static ByteSize requires_cross_modify_fence_offset()  { return byte_offset_of(JavaThread, _requires_cross_modify_fence); })
 826 
 827   static ByteSize cont_entry_offset()         { return byte_offset_of(JavaThread, _cont_entry); }
 828   static ByteSize cont_fastpath_offset()      { return byte_offset_of(JavaThread, _cont_fastpath); }
 829   static ByteSize held_monitor_count_offset() { return byte_offset_of(JavaThread, _held_monitor_count); }
 830 
 831 #if INCLUDE_JVMTI
 832   static ByteSize is_in_VTMS_transition_offset()     { return byte_offset_of(JavaThread, _is_in_VTMS_transition); }
 833   static ByteSize is_in_tmp_VTMS_transition_offset() { return byte_offset_of(JavaThread, _is_in_tmp_VTMS_transition); }
 834   static ByteSize is_disable_suspend_offset()        { return byte_offset_of(JavaThread, _is_disable_suspend); }
 835 #endif
 836 
 837   // Returns the jni environment for this thread
 838   JNIEnv* jni_environment()                      { return &_jni_environment; }
 839 
 840   // Returns the current thread as indicated by the given JNIEnv.
 841   // We don't assert it is Thread::current here as that is done at the
 842   // external JNI entry points where the JNIEnv is passed into the VM.
 843   static JavaThread* thread_from_jni_environment(JNIEnv* env) {
 844     JavaThread* current = reinterpret_cast<JavaThread*>(((intptr_t)env - in_bytes(jni_environment_offset())));
 845     // We can't normally get here in a thread that has completed its
 846     // execution and so "is_terminated", except when the call is from
 847     // AsyncGetCallTrace, which can be triggered by a signal at any point in
 848     // a thread's lifecycle. A thread is also considered terminated if the VM
 849     // has exited, so we have to check this and block in case this is a daemon
 850     // thread returning to the VM (the JNI DirectBuffer entry points rely on
 851     // this).
 852     if (current->is_terminated()) {
 853       current->block_if_vm_exited();
 854     }
 855     return current;
 856   }
 857 
 858   // JNI critical regions. These can nest.
 859   bool in_critical()    { return _jni_active_critical > 0; }
 860   bool in_last_critical()  { return _jni_active_critical == 1; }
 861   inline void enter_critical();
 862   void exit_critical() {
 863     assert(Thread::current() == this, "this must be current thread");
 864     _jni_active_critical--;
 865     assert(_jni_active_critical >= 0, "JNI critical nesting problem?");
 866   }
 867 
 868   // Checked JNI: is the programmer required to check for exceptions, if so specify
 869   // which function name. Returning to a Java frame should implicitly clear the
 870   // pending check, this is done for Native->Java transitions (i.e. user JNI code).
 871   // VM->Java transitions are not cleared, it is expected that JNI code enclosed
 872   // within ThreadToNativeFromVM makes proper exception checks (i.e. VM internal).
 873   bool is_pending_jni_exception_check() const { return _pending_jni_exception_check_fn != nullptr; }
 874   void clear_pending_jni_exception_check() { _pending_jni_exception_check_fn = nullptr; }
 875   const char* get_pending_jni_exception_check() const { return _pending_jni_exception_check_fn; }
 876   void set_pending_jni_exception_check(const char* fn_name) { _pending_jni_exception_check_fn = (char*) fn_name; }
 877 
 878   // For deadlock detection
 879   int depth_first_number() { return _depth_first_number; }
 880   void set_depth_first_number(int dfn) { _depth_first_number = dfn; }
 881 
 882  private:
 883   void set_monitor_chunks(MonitorChunk* monitor_chunks) { _monitor_chunks = monitor_chunks; }
 884 
 885  public:
 886   MonitorChunk* monitor_chunks() const           { return _monitor_chunks; }
 887   void add_monitor_chunk(MonitorChunk* chunk);
 888   void remove_monitor_chunk(MonitorChunk* chunk);
 889   bool in_deopt_handler() const                  { return _in_deopt_handler > 0; }
 890   void inc_in_deopt_handler()                    { _in_deopt_handler++; }
 891   void dec_in_deopt_handler() {
 892     assert(_in_deopt_handler > 0, "mismatched deopt nesting");
 893     if (_in_deopt_handler > 0) { // robustness
 894       _in_deopt_handler--;
 895     }
 896   }
 897 
 898  private:
 899   void set_entry_point(ThreadFunction entry_point) { _entry_point = entry_point; }
 900 
 901   // factor out low-level mechanics for use in both normal and error cases
 902   const char* get_thread_name_string(char* buf = nullptr, int buflen = 0) const;
 903 
 904  public:
 905 
 906   // Frame iteration; calls the function f for all frames on the stack
 907   void frames_do(void f(frame*, const RegisterMap*));
 908 
 909   // Memory operations
 910   void oops_do_frames(OopClosure* f, CodeBlobClosure* cf);
 911   void oops_do_no_frames(OopClosure* f, CodeBlobClosure* cf);
 912 
 913   // GC operations
 914   virtual void nmethods_do(CodeBlobClosure* cf);
 915 
 916   // RedefineClasses Support
 917   void metadata_do(MetadataClosure* f);
 918 
 919   // Debug method asserting thread states are correct during a handshake operation.
 920   DEBUG_ONLY(void verify_states_for_handshake();)
 921 
 922   // Misc. operations
 923   const char* name() const;
 924   const char* name_raw() const;
 925   const char* type_name() const { return "JavaThread"; }
 926   static const char* name_for(oop thread_obj);
 927 
 928   void print_on(outputStream* st, bool print_extended_info) const;
 929   void print_on(outputStream* st) const { print_on(st, false); }
 930   void print() const;
 931   void print_thread_state_on(outputStream*) const;
 932   void print_on_error(outputStream* st, char* buf, int buflen) const;
 933   void print_name_on_error(outputStream* st, char* buf, int buflen) const;
 934   void verify();
 935 
 936   // Accessing frames
 937   frame last_frame() {
 938     _anchor.make_walkable();
 939     return pd_last_frame();
 940   }
 941   javaVFrame* last_java_vframe(RegisterMap* reg_map) { return last_java_vframe(last_frame(), reg_map); }
 942 
 943   frame carrier_last_frame(RegisterMap* reg_map);
 944   javaVFrame* carrier_last_java_vframe(RegisterMap* reg_map) { return last_java_vframe(carrier_last_frame(reg_map), reg_map); }
 945 
 946   frame vthread_last_frame();
 947   javaVFrame* vthread_last_java_vframe(RegisterMap* reg_map) { return last_java_vframe(vthread_last_frame(), reg_map); }
 948 
 949   frame platform_thread_last_frame(RegisterMap* reg_map);
 950   javaVFrame*  platform_thread_last_java_vframe(RegisterMap* reg_map) {
 951     return last_java_vframe(platform_thread_last_frame(reg_map), reg_map);
 952   }
 953 
 954   javaVFrame* last_java_vframe(const frame f, RegisterMap* reg_map);
 955 
 956   // Returns method at 'depth' java or native frames down the stack
 957   // Used for security checks
 958   Klass* security_get_caller_class(int depth);
 959 
 960   // Print stack trace in external format
 961   // These variants print carrier/platform thread information only.
 962   void print_stack_on(outputStream* st);
 963   void print_stack() { print_stack_on(tty); }
 964   // This prints the currently mounted virtual thread.
 965   void print_vthread_stack_on(outputStream* st);
 966   // This prints the active stack: either carrier/platform or virtual.
 967   void print_active_stack_on(outputStream* st);
 968   // Print current stack trace for checked JNI warnings and JNI fatal errors.
 969   // This is the external format from above, but selecting the platform
 970   // or vthread as applicable.
 971   void print_jni_stack();
 972 
 973   void print_native_stack_on(outputStream* st);
 974 
 975   // Print stack traces in various internal formats
 976   void trace_stack()                             PRODUCT_RETURN;
 977   void trace_stack_from(vframe* start_vf)        PRODUCT_RETURN;
 978   void trace_frames()                            PRODUCT_RETURN;
 979 
 980   // Print an annotated view of the stack frames
 981   void print_frame_layout(int depth = 0, bool validate_only = false) NOT_DEBUG_RETURN;
 982   void validate_frame_layout() {
 983     print_frame_layout(0, true);
 984   }
 985 
 986   // Function for testing deoptimization
 987   void deoptimize();
 988   void make_zombies();
 989 
 990   void deoptimize_marked_methods();
 991 
 992  public:
 993   // Returns the running thread as a JavaThread
 994   static JavaThread* current() {
 995     return JavaThread::cast(Thread::current());
 996   }
 997 
 998   // Returns the current thread as a JavaThread, or nullptr if not attached
 999   static inline JavaThread* current_or_null();
1000 
1001   // Casts
1002   static JavaThread* cast(Thread* t) {
1003     assert(t->is_Java_thread(), "incorrect cast to JavaThread");
1004     return static_cast<JavaThread*>(t);
1005   }
1006 
1007   static const JavaThread* cast(const Thread* t) {
1008     assert(t->is_Java_thread(), "incorrect cast to const JavaThread");
1009     return static_cast<const JavaThread*>(t);
1010   }
1011 
1012   // Returns the active Java thread.  Do not use this if you know you are calling
1013   // from a JavaThread, as it's slower than JavaThread::current.  If called from
1014   // the VMThread, it also returns the JavaThread that instigated the VMThread's
1015   // operation.  You may not want that either.
1016   static JavaThread* active();
1017 
1018  protected:
1019   virtual void pre_run();
1020   virtual void run();
1021   void thread_main_inner();
1022   virtual void post_run();
1023 
1024  public:
1025   // Thread local information maintained by JVMTI.
1026   void set_jvmti_thread_state(JvmtiThreadState *value)                           { _jvmti_thread_state = value; }
1027   // A JvmtiThreadState is lazily allocated. This jvmti_thread_state()
1028   // getter is used to get this JavaThread's JvmtiThreadState if it has
1029   // one which means null can be returned. JvmtiThreadState::state_for()
1030   // is used to get the specified JavaThread's JvmtiThreadState if it has
1031   // one or it allocates a new JvmtiThreadState for the JavaThread and
1032   // returns it. JvmtiThreadState::state_for() will return null only if
1033   // the specified JavaThread is exiting.
1034   JvmtiThreadState *jvmti_thread_state() const                                   { return _jvmti_thread_state; }
1035   static ByteSize jvmti_thread_state_offset()                                    { return byte_offset_of(JavaThread, _jvmti_thread_state); }
1036 
1037 #if INCLUDE_JVMTI
1038   // Rebind JVMTI thread state from carrier to virtual or from virtual to carrier.
1039   JvmtiThreadState *rebind_to_jvmti_thread_state_of(oop thread_oop);
1040 #endif
1041 
1042   // JVMTI PopFrame support
1043   // Setting and clearing popframe_condition
1044   // All of these enumerated values are bits. popframe_pending
1045   // indicates that a PopFrame() has been requested and not yet been
1046   // completed. popframe_processing indicates that that PopFrame() is in
1047   // the process of being completed. popframe_force_deopt_reexecution_bit
1048   // indicates that special handling is required when returning to a
1049   // deoptimized caller.
1050   enum PopCondition {
1051     popframe_inactive                      = 0x00,
1052     popframe_pending_bit                   = 0x01,
1053     popframe_processing_bit                = 0x02,
1054     popframe_force_deopt_reexecution_bit   = 0x04
1055   };
1056   PopCondition popframe_condition()                   { return (PopCondition) _popframe_condition; }
1057   void set_popframe_condition(PopCondition c)         { _popframe_condition = c; }
1058   void set_popframe_condition_bit(PopCondition c)     { _popframe_condition |= c; }
1059   void clear_popframe_condition()                     { _popframe_condition = popframe_inactive; }
1060   static ByteSize popframe_condition_offset()         { return byte_offset_of(JavaThread, _popframe_condition); }
1061   bool has_pending_popframe()                         { return (popframe_condition() & popframe_pending_bit) != 0; }
1062   bool popframe_forcing_deopt_reexecution()           { return (popframe_condition() & popframe_force_deopt_reexecution_bit) != 0; }
1063 
1064   bool pop_frame_in_process(void)                     { return ((_popframe_condition & popframe_processing_bit) != 0); }
1065   void set_pop_frame_in_process(void)                 { _popframe_condition |= popframe_processing_bit; }
1066   void clr_pop_frame_in_process(void)                 { _popframe_condition &= ~popframe_processing_bit; }
1067 
1068   int frames_to_pop_failed_realloc() const            { return _frames_to_pop_failed_realloc; }
1069   void set_frames_to_pop_failed_realloc(int nb)       { _frames_to_pop_failed_realloc = nb; }
1070   void dec_frames_to_pop_failed_realloc()             { _frames_to_pop_failed_realloc--; }
1071 
1072  private:
1073   // Saved incoming arguments to popped frame.
1074   // Used only when popped interpreted frame returns to deoptimized frame.
1075   void*    _popframe_preserved_args;
1076   int      _popframe_preserved_args_size;
1077 
1078  public:
1079   void  popframe_preserve_args(ByteSize size_in_bytes, void* start);
1080   void* popframe_preserved_args();
1081   ByteSize popframe_preserved_args_size();
1082   WordSize popframe_preserved_args_size_in_words();
1083   void  popframe_free_preserved_args();
1084 
1085 
1086  private:
1087   JvmtiThreadState *_jvmti_thread_state;
1088 
1089   // Used by the interpreter in fullspeed mode for frame pop, method
1090   // entry, method exit and single stepping support. This field is
1091   // only set to non-zero at a safepoint or using a direct handshake
1092   // (see EnterInterpOnlyModeClosure).
1093   // It can be set to zero asynchronously to this threads execution (i.e., without
1094   // safepoint/handshake or a lock) so we have to be very careful.
1095   // Accesses by other threads are synchronized using JvmtiThreadState_lock though.
1096   int               _interp_only_mode;
1097 
1098  public:
1099   // used by the interpreter for fullspeed debugging support (see above)
1100   static ByteSize interp_only_mode_offset() { return byte_offset_of(JavaThread, _interp_only_mode); }
1101   bool is_interp_only_mode()                { return (_interp_only_mode != 0); }
1102   int get_interp_only_mode()                { return _interp_only_mode; }
1103   int set_interp_only_mode(int val)         { return _interp_only_mode = val; }
1104   void increment_interp_only_mode()         { ++_interp_only_mode; }
1105   void decrement_interp_only_mode()         { --_interp_only_mode; }
1106 
1107   // support for cached flag that indicates whether exceptions need to be posted for this thread
1108   // if this is false, we can avoid deoptimizing when events are thrown
1109   // this gets set to reflect whether jvmtiExport::post_exception_throw would actually do anything
1110  private:
1111   int    _should_post_on_exceptions_flag;
1112 
1113  public:
1114   void  set_should_post_on_exceptions_flag(int val)  { _should_post_on_exceptions_flag = val; }
1115 
1116  private:
1117   ThreadStatistics *_thread_stat;
1118 
1119  public:
1120   ThreadStatistics* get_thread_stat() const    { return _thread_stat; }
1121 
1122   // Return a blocker object for which this thread is blocked parking.
1123   oop current_park_blocker();
1124 
1125  private:
1126   static size_t _stack_size_at_create;
1127 
1128  public:
1129   static inline size_t stack_size_at_create(void) {
1130     return _stack_size_at_create;
1131   }
1132   static inline void set_stack_size_at_create(size_t value) {
1133     _stack_size_at_create = value;
1134   }
1135 
1136   // Machine dependent stuff
1137 #include OS_CPU_HEADER(javaThread)
1138 
1139   // JSR166 per-thread parker
1140  private:
1141   Parker _parker;
1142  public:
1143   Parker* parker() { return &_parker; }
1144 
1145  public:
1146   // clearing/querying jni attach status
1147   bool is_attaching_via_jni() const { return _jni_attach_state == _attaching_via_jni; }
1148   bool has_attached_via_jni() const { return is_attaching_via_jni() || _jni_attach_state == _attached_via_jni; }
1149   inline void set_done_attaching_via_jni();
1150 
1151   // Stack dump assistance:
1152   // Track the class we want to initialize but for which we have to wait
1153   // on its init_lock() because it is already being initialized.
1154   void set_class_to_be_initialized(InstanceKlass* k);
1155   InstanceKlass* class_to_be_initialized() const;
1156 
1157   // The most recent active <clinit> invocation is tracked by this variable.
1158   // The setter returns the previous value, so it can be restored later if needed.
1159   InstanceKlass* set_class_being_initialized(InstanceKlass* k);
1160   InstanceKlass* class_being_initialized() const;
1161 
1162 private:
1163   InstanceKlass* _class_to_be_initialized;
1164   InstanceKlass* _class_being_initialized;
1165 
1166   // java.lang.Thread.sleep support
1167   ParkEvent * _SleepEvent;
1168 public:
1169   bool sleep(jlong millis);
1170   bool sleep_nanos(jlong nanos);
1171 
1172   // java.lang.Thread interruption support
1173   void interrupt();
1174   bool is_interrupted(bool clear_interrupted);
1175 
1176 private:
1177   LockStack _lock_stack;
1178 
1179 public:
1180   LockStack& lock_stack() { return _lock_stack; }
1181 
1182   static ByteSize lock_stack_offset()      { return byte_offset_of(JavaThread, _lock_stack); }
1183   // Those offsets are used in code generators to access the LockStack that is embedded in this
1184   // JavaThread structure. Those accesses are relative to the current thread, which
1185   // is typically in a dedicated register.
1186   static ByteSize lock_stack_top_offset()  { return lock_stack_offset() + LockStack::top_offset(); }
1187   static ByteSize lock_stack_base_offset() { return lock_stack_offset() + LockStack::base_offset(); }
1188 
1189   static OopStorage* thread_oop_storage();
1190 
1191   static void verify_cross_modify_fence_failure(JavaThread *thread) PRODUCT_RETURN;
1192 
1193   // Helper function to create the java.lang.Thread object for a
1194   // VM-internal thread. The thread will have the given name and be
1195   // part of the System ThreadGroup.
1196   static Handle create_system_thread_object(const char* name, TRAPS);
1197 
1198   // Helper function to start a VM-internal daemon thread.
1199   // E.g. ServiceThread, NotificationThread, CompilerThread etc.
1200   static void start_internal_daemon(JavaThread* current, JavaThread* target,
1201                                     Handle thread_oop, ThreadPriority prio);
1202 
1203   // Helper function to do vm_exit_on_initialization for osthread
1204   // resource allocation failure.
1205   static void vm_exit_on_osthread_failure(JavaThread* thread);
1206 
1207   // Deferred OopHandle release support
1208  private:
1209   // List of OopHandles to be released - guarded by the Service_lock.
1210   static OopHandleList* _oop_handle_list;
1211   // Add our OopHandles to the list for the service thread to release.
1212   void add_oop_handles_for_release();
1213   // Called by the ServiceThread to release the OopHandles.
1214   static void release_oop_handles();
1215   // Called by the ServiceThread to poll if there are any OopHandles to release.
1216   // Called when holding the Service_lock.
1217   static bool has_oop_handles_to_release() {
1218     return _oop_handle_list != nullptr;
1219   }
1220 };
1221 
1222 inline JavaThread* JavaThread::current_or_null() {
1223   Thread* current = Thread::current_or_null();
1224   return current != nullptr ? JavaThread::cast(current) : nullptr;
1225 }
1226 
1227 class UnlockFlagSaver {
1228   private:
1229     JavaThread* _thread;
1230     bool _do_not_unlock;
1231   public:
1232     UnlockFlagSaver(JavaThread* t) {
1233       _thread = t;
1234       _do_not_unlock = t->do_not_unlock_if_synchronized();
1235       t->set_do_not_unlock_if_synchronized(false);
1236     }
1237     ~UnlockFlagSaver() {
1238       _thread->set_do_not_unlock_if_synchronized(_do_not_unlock);
1239     }
1240 };
1241 
1242 class JNIHandleMark : public StackObj {
1243   JavaThread* _thread;
1244  public:
1245   JNIHandleMark(JavaThread* thread) : _thread(thread) {
1246     thread->push_jni_handle_block();
1247   }
1248   ~JNIHandleMark() { _thread->pop_jni_handle_block(); }
1249 };
1250 
1251 #endif // SHARE_RUNTIME_JAVATHREAD_HPP