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1 // Copyright 2012 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef V8_DEBUG_H_
6 #define V8_DEBUG_H_
7 
8 #include "src/allocation.h"
9 #include "src/arguments.h"
10 #include "src/assembler.h"
11 #include "src/execution.h"
12 #include "src/factory.h"
13 #include "src/flags.h"
14 #include "src/frames-inl.h"
15 #include "src/hashmap.h"
16 #include "src/liveedit.h"
17 #include "src/platform.h"
18 #include "src/string-stream.h"
19 #include "src/v8threads.h"
20 
21 #include "include/v8-debug.h"
22 
23 namespace v8 {
24 namespace internal {
25 
26 
27 // Forward declarations.
28 class DebugScope;
29 
30 
31 // Step actions. NOTE: These values are in macros.py as well.
32 enum StepAction {
33   StepNone = -1,  // Stepping not prepared.
34   StepOut = 0,   // Step out of the current function.
35   StepNext = 1,  // Step to the next statement in the current function.
36   StepIn = 2,    // Step into new functions invoked or the next statement
37                  // in the current function.
38   StepMin = 3,   // Perform a minimum step in the current function.
39   StepInMin = 4  // Step into new functions invoked or perform a minimum step
40                  // in the current function.
41 };
42 
43 
44 // Type of exception break. NOTE: These values are in macros.py as well.
45 enum ExceptionBreakType {
46   BreakException = 0,
47   BreakUncaughtException = 1
48 };
49 
50 
51 // Type of exception break. NOTE: These values are in macros.py as well.
52 enum BreakLocatorType {
53   ALL_BREAK_LOCATIONS = 0,
54   SOURCE_BREAK_LOCATIONS = 1
55 };
56 
57 
58 // The different types of breakpoint position alignments.
59 // Must match Debug.BreakPositionAlignment in debug-debugger.js
60 enum BreakPositionAlignment {
61   STATEMENT_ALIGNED = 0,
62   BREAK_POSITION_ALIGNED = 1
63 };
64 
65 
66 // Class for iterating through the break points in a function and changing
67 // them.
68 class BreakLocationIterator {
69  public:
70   explicit BreakLocationIterator(Handle<DebugInfo> debug_info,
71                                  BreakLocatorType type);
72   virtual ~BreakLocationIterator();
73 
74   void Next();
75   void Next(int count);
76   void FindBreakLocationFromAddress(Address pc);
77   void FindBreakLocationFromPosition(int position,
78       BreakPositionAlignment alignment);
79   void Reset();
80   bool Done() const;
81   void SetBreakPoint(Handle<Object> break_point_object);
82   void ClearBreakPoint(Handle<Object> break_point_object);
83   void SetOneShot();
84   void ClearOneShot();
85   bool IsStepInLocation(Isolate* isolate);
86   void PrepareStepIn(Isolate* isolate);
87   bool IsExit() const;
88   bool HasBreakPoint();
89   bool IsDebugBreak();
90   Object* BreakPointObjects();
91   void ClearAllDebugBreak();
92 
93 
code_position()94   inline int code_position() {
95     return static_cast<int>(pc() - debug_info_->code()->entry());
96   }
break_point()97   inline int break_point() { return break_point_; }
position()98   inline int position() { return position_; }
statement_position()99   inline int statement_position() { return statement_position_; }
pc()100   inline Address pc() { return reloc_iterator_->rinfo()->pc(); }
code()101   inline Code* code() { return debug_info_->code(); }
rinfo()102   inline RelocInfo* rinfo() { return reloc_iterator_->rinfo(); }
rmode()103   inline RelocInfo::Mode rmode() const {
104     return reloc_iterator_->rinfo()->rmode();
105   }
original_rinfo()106   inline RelocInfo* original_rinfo() {
107     return reloc_iterator_original_->rinfo();
108   }
original_rmode()109   inline RelocInfo::Mode original_rmode() const {
110     return reloc_iterator_original_->rinfo()->rmode();
111   }
112 
113   bool IsDebuggerStatement();
114 
115  protected:
116   bool RinfoDone() const;
117   void RinfoNext();
118 
119   BreakLocatorType type_;
120   int break_point_;
121   int position_;
122   int statement_position_;
123   Handle<DebugInfo> debug_info_;
124   RelocIterator* reloc_iterator_;
125   RelocIterator* reloc_iterator_original_;
126 
127  private:
128   void SetDebugBreak();
129   void ClearDebugBreak();
130 
131   void SetDebugBreakAtIC();
132   void ClearDebugBreakAtIC();
133 
134   bool IsDebugBreakAtReturn();
135   void SetDebugBreakAtReturn();
136   void ClearDebugBreakAtReturn();
137 
138   bool IsDebugBreakSlot();
139   bool IsDebugBreakAtSlot();
140   void SetDebugBreakAtSlot();
141   void ClearDebugBreakAtSlot();
142 
143   DISALLOW_COPY_AND_ASSIGN(BreakLocationIterator);
144 };
145 
146 
147 // Cache of all script objects in the heap. When a script is added a weak handle
148 // to it is created and that weak handle is stored in the cache. The weak handle
149 // callback takes care of removing the script from the cache. The key used in
150 // the cache is the script id.
151 class ScriptCache : private HashMap {
152  public:
153   explicit ScriptCache(Isolate* isolate);
~ScriptCache()154   virtual ~ScriptCache() { Clear(); }
155 
156   // Add script to the cache.
157   void Add(Handle<Script> script);
158 
159   // Return the scripts in the cache.
160   Handle<FixedArray> GetScripts();
161 
162   // Generate debugger events for collected scripts.
163   void ProcessCollectedScripts();
164 
165  private:
166   // Calculate the hash value from the key (script id).
Hash(int key)167   static uint32_t Hash(int key) {
168     return ComputeIntegerHash(key, v8::internal::kZeroHashSeed);
169   }
170 
171   // Clear the cache releasing all the weak handles.
172   void Clear();
173 
174   // Weak handle callback for scripts in the cache.
175   static void HandleWeakScript(
176       const v8::WeakCallbackData<v8::Value, void>& data);
177 
178   Isolate* isolate_;
179   // List used during GC to temporarily store id's of collected scripts.
180   List<int> collected_scripts_;
181 };
182 
183 
184 // Linked list holding debug info objects. The debug info objects are kept as
185 // weak handles to avoid a debug info object to keep a function alive.
186 class DebugInfoListNode {
187  public:
188   explicit DebugInfoListNode(DebugInfo* debug_info);
189   virtual ~DebugInfoListNode();
190 
next()191   DebugInfoListNode* next() { return next_; }
set_next(DebugInfoListNode * next)192   void set_next(DebugInfoListNode* next) { next_ = next; }
debug_info()193   Handle<DebugInfo> debug_info() { return debug_info_; }
194 
195  private:
196   // Global (weak) handle to the debug info object.
197   Handle<DebugInfo> debug_info_;
198 
199   // Next pointer for linked list.
200   DebugInfoListNode* next_;
201 };
202 
203 
204 
205 // Message delivered to the message handler callback. This is either a debugger
206 // event or the response to a command.
207 class MessageImpl: public v8::Debug::Message {
208  public:
209   // Create a message object for a debug event.
210   static MessageImpl NewEvent(DebugEvent event,
211                               bool running,
212                               Handle<JSObject> exec_state,
213                               Handle<JSObject> event_data);
214 
215   // Create a message object for the response to a debug command.
216   static MessageImpl NewResponse(DebugEvent event,
217                                  bool running,
218                                  Handle<JSObject> exec_state,
219                                  Handle<JSObject> event_data,
220                                  Handle<String> response_json,
221                                  v8::Debug::ClientData* client_data);
222 
223   // Implementation of interface v8::Debug::Message.
224   virtual bool IsEvent() const;
225   virtual bool IsResponse() const;
226   virtual DebugEvent GetEvent() const;
227   virtual bool WillStartRunning() const;
228   virtual v8::Handle<v8::Object> GetExecutionState() const;
229   virtual v8::Handle<v8::Object> GetEventData() const;
230   virtual v8::Handle<v8::String> GetJSON() const;
231   virtual v8::Handle<v8::Context> GetEventContext() const;
232   virtual v8::Debug::ClientData* GetClientData() const;
233   virtual v8::Isolate* GetIsolate() const;
234 
235  private:
236   MessageImpl(bool is_event,
237               DebugEvent event,
238               bool running,
239               Handle<JSObject> exec_state,
240               Handle<JSObject> event_data,
241               Handle<String> response_json,
242               v8::Debug::ClientData* client_data);
243 
244   bool is_event_;  // Does this message represent a debug event?
245   DebugEvent event_;  // Debug event causing the break.
246   bool running_;  // Will the VM start running after this event?
247   Handle<JSObject> exec_state_;  // Current execution state.
248   Handle<JSObject> event_data_;  // Data associated with the event.
249   Handle<String> response_json_;  // Response JSON if message holds a response.
250   v8::Debug::ClientData* client_data_;  // Client data passed with the request.
251 };
252 
253 
254 // Details of the debug event delivered to the debug event listener.
255 class EventDetailsImpl : public v8::Debug::EventDetails {
256  public:
257   EventDetailsImpl(DebugEvent event,
258                    Handle<JSObject> exec_state,
259                    Handle<JSObject> event_data,
260                    Handle<Object> callback_data,
261                    v8::Debug::ClientData* client_data);
262   virtual DebugEvent GetEvent() const;
263   virtual v8::Handle<v8::Object> GetExecutionState() const;
264   virtual v8::Handle<v8::Object> GetEventData() const;
265   virtual v8::Handle<v8::Context> GetEventContext() const;
266   virtual v8::Handle<v8::Value> GetCallbackData() const;
267   virtual v8::Debug::ClientData* GetClientData() const;
268  private:
269   DebugEvent event_;  // Debug event causing the break.
270   Handle<JSObject> exec_state_;         // Current execution state.
271   Handle<JSObject> event_data_;         // Data associated with the event.
272   Handle<Object> callback_data_;        // User data passed with the callback
273                                         // when it was registered.
274   v8::Debug::ClientData* client_data_;  // Data passed to DebugBreakForCommand.
275 };
276 
277 
278 // Message send by user to v8 debugger or debugger output message.
279 // In addition to command text it may contain a pointer to some user data
280 // which are expected to be passed along with the command reponse to message
281 // handler.
282 class CommandMessage {
283  public:
284   static CommandMessage New(const Vector<uint16_t>& command,
285                             v8::Debug::ClientData* data);
286   CommandMessage();
287 
288   // Deletes user data and disposes of the text.
289   void Dispose();
text()290   Vector<uint16_t> text() const { return text_; }
client_data()291   v8::Debug::ClientData* client_data() const { return client_data_; }
292  private:
293   CommandMessage(const Vector<uint16_t>& text,
294                  v8::Debug::ClientData* data);
295 
296   Vector<uint16_t> text_;
297   v8::Debug::ClientData* client_data_;
298 };
299 
300 
301 // A Queue of CommandMessage objects.  A thread-safe version is
302 // LockingCommandMessageQueue, based on this class.
303 class CommandMessageQueue BASE_EMBEDDED {
304  public:
305   explicit CommandMessageQueue(int size);
306   ~CommandMessageQueue();
IsEmpty()307   bool IsEmpty() const { return start_ == end_; }
308   CommandMessage Get();
309   void Put(const CommandMessage& message);
Clear()310   void Clear() { start_ = end_ = 0; }  // Queue is empty after Clear().
311  private:
312   // Doubles the size of the message queue, and copies the messages.
313   void Expand();
314 
315   CommandMessage* messages_;
316   int start_;
317   int end_;
318   int size_;  // The size of the queue buffer.  Queue can hold size-1 messages.
319 };
320 
321 
322 // LockingCommandMessageQueue is a thread-safe circular buffer of CommandMessage
323 // messages.  The message data is not managed by LockingCommandMessageQueue.
324 // Pointers to the data are passed in and out. Implemented by adding a
325 // Mutex to CommandMessageQueue.  Includes logging of all puts and gets.
326 class LockingCommandMessageQueue BASE_EMBEDDED {
327  public:
328   LockingCommandMessageQueue(Logger* logger, int size);
329   bool IsEmpty() const;
330   CommandMessage Get();
331   void Put(const CommandMessage& message);
332   void Clear();
333  private:
334   Logger* logger_;
335   CommandMessageQueue queue_;
336   mutable Mutex mutex_;
337   DISALLOW_COPY_AND_ASSIGN(LockingCommandMessageQueue);
338 };
339 
340 
341 class PromiseOnStack {
342  public:
343   PromiseOnStack(Isolate* isolate,
344                  PromiseOnStack* prev,
345                  Handle<JSFunction> getter);
346   ~PromiseOnStack();
handler()347   StackHandler* handler() { return handler_; }
getter()348   Handle<JSFunction> getter() { return getter_; }
prev()349   PromiseOnStack* prev() { return prev_; }
350  private:
351   Isolate* isolate_;
352   StackHandler* handler_;
353   Handle<JSFunction> getter_;
354   PromiseOnStack* prev_;
355 };
356 
357 
358 // This class contains the debugger support. The main purpose is to handle
359 // setting break points in the code.
360 //
361 // This class controls the debug info for all functions which currently have
362 // active breakpoints in them. This debug info is held in the heap root object
363 // debug_info which is a FixedArray. Each entry in this list is of class
364 // DebugInfo.
365 class Debug {
366  public:
367   enum AfterCompileFlags {
368     NO_AFTER_COMPILE_FLAGS,
369     SEND_WHEN_DEBUGGING
370   };
371 
372   // Debug event triggers.
373   void OnDebugBreak(Handle<Object> break_points_hit, bool auto_continue);
374   void OnException(Handle<Object> exception, bool uncaught);
375   void OnBeforeCompile(Handle<Script> script);
376   void OnAfterCompile(Handle<Script> script,
377                       AfterCompileFlags after_compile_flags);
378   void OnScriptCollected(int id);
379 
380   // API facing.
381   void SetEventListener(Handle<Object> callback, Handle<Object> data);
382   void SetMessageHandler(v8::Debug::MessageHandler handler);
383   void EnqueueCommandMessage(Vector<const uint16_t> command,
384                              v8::Debug::ClientData* client_data = NULL);
385   // Enqueue a debugger command to the command queue for event listeners.
386   void EnqueueDebugCommand(v8::Debug::ClientData* client_data = NULL);
387   MUST_USE_RESULT MaybeHandle<Object> Call(Handle<JSFunction> fun,
388                                            Handle<Object> data);
389   Handle<Context> GetDebugContext();
390   void HandleDebugBreak();
391   void ProcessDebugMessages(bool debug_command_only);
392 
393   // Internal logic
394   bool Load();
395   void Break(Arguments args, JavaScriptFrame*);
396   void SetAfterBreakTarget(JavaScriptFrame* frame);
397 
398   // Scripts handling.
399   Handle<FixedArray> GetLoadedScripts();
400 
401   // Break point handling.
402   bool SetBreakPoint(Handle<JSFunction> function,
403                      Handle<Object> break_point_object,
404                      int* source_position);
405   bool SetBreakPointForScript(Handle<Script> script,
406                               Handle<Object> break_point_object,
407                               int* source_position,
408                               BreakPositionAlignment alignment);
409   void ClearBreakPoint(Handle<Object> break_point_object);
410   void ClearAllBreakPoints();
411   void FloodWithOneShot(Handle<JSFunction> function);
412   void FloodBoundFunctionWithOneShot(Handle<JSFunction> function);
413   void FloodHandlerWithOneShot();
414   void ChangeBreakOnException(ExceptionBreakType type, bool enable);
415   bool IsBreakOnException(ExceptionBreakType type);
416 
417   // Stepping handling.
418   void PrepareStep(StepAction step_action,
419                    int step_count,
420                    StackFrame::Id frame_id);
421   void ClearStepping();
422   void ClearStepOut();
IsStepping()423   bool IsStepping() { return thread_local_.step_count_ > 0; }
424   bool StepNextContinue(BreakLocationIterator* break_location_iterator,
425                         JavaScriptFrame* frame);
StepInActive()426   bool StepInActive() { return thread_local_.step_into_fp_ != 0; }
427   void HandleStepIn(Handle<JSFunction> function,
428                     Handle<Object> holder,
429                     Address fp,
430                     bool is_constructor);
StepOutActive()431   bool StepOutActive() { return thread_local_.step_out_fp_ != 0; }
432 
433   // Purge all code objects that have no debug break slots.
434   void PrepareForBreakPoints();
435 
436   // Returns whether the operation succeeded. Compilation can only be triggered
437   // if a valid closure is passed as the second argument, otherwise the shared
438   // function needs to be compiled already.
439   bool EnsureDebugInfo(Handle<SharedFunctionInfo> shared,
440                        Handle<JSFunction> function);
441   static Handle<DebugInfo> GetDebugInfo(Handle<SharedFunctionInfo> shared);
442   static bool HasDebugInfo(Handle<SharedFunctionInfo> shared);
443 
444   // This function is used in FunctionNameUsing* tests.
445   Object* FindSharedFunctionInfoInScript(Handle<Script> script, int position);
446 
447   // Returns true if the current stub call is patched to call the debugger.
448   static bool IsDebugBreak(Address addr);
449   // Returns true if the current return statement has been patched to be
450   // a debugger breakpoint.
451   static bool IsDebugBreakAtReturn(RelocInfo* rinfo);
452 
453   static Handle<Object> GetSourceBreakLocations(
454       Handle<SharedFunctionInfo> shared,
455       BreakPositionAlignment position_aligment);
456 
457   // Check whether a global object is the debug global object.
458   bool IsDebugGlobal(GlobalObject* global);
459 
460   // Check whether this frame is just about to return.
461   bool IsBreakAtReturn(JavaScriptFrame* frame);
462 
463   // Promise handling.
464   void PromiseHandlePrologue(Handle<JSFunction> promise_getter);
465   void PromiseHandleEpilogue();
466 
467   // Support for LiveEdit
468   void FramesHaveBeenDropped(StackFrame::Id new_break_frame_id,
469                              LiveEdit::FrameDropMode mode,
470                              Object** restarter_frame_function_pointer);
471 
472   // Passed to MakeWeak.
473   static void HandleWeakDebugInfo(
474       const v8::WeakCallbackData<v8::Value, void>& data);
475 
476   // Threading support.
477   char* ArchiveDebug(char* to);
478   char* RestoreDebug(char* from);
479   static int ArchiveSpacePerThread();
FreeThreadResources()480   void FreeThreadResources() { }
481 
482   // Record function from which eval was called.
483   static void RecordEvalCaller(Handle<Script> script);
484 
485   // Garbage collection notifications.
486   void AfterGarbageCollection();
487 
488   // Flags and states.
debugger_entry()489   DebugScope* debugger_entry() { return thread_local_.current_debug_scope_; }
debug_context()490   inline Handle<Context> debug_context() { return debug_context_; }
set_live_edit_enabled(bool v)491   void set_live_edit_enabled(bool v) { live_edit_enabled_ = v; }
live_edit_enabled()492   bool live_edit_enabled() const {
493     return FLAG_enable_liveedit && live_edit_enabled_ ;
494   }
495 
is_active()496   inline bool is_active() const { return is_active_; }
is_loaded()497   inline bool is_loaded() const { return !debug_context_.is_null(); }
has_break_points()498   inline bool has_break_points() const { return has_break_points_; }
in_debug_scope()499   inline bool in_debug_scope() const {
500     return thread_local_.current_debug_scope_ != NULL;
501   }
set_disable_break(bool v)502   void set_disable_break(bool v) { break_disabled_ = v; }
503 
break_frame_id()504   StackFrame::Id break_frame_id() { return thread_local_.break_frame_id_; }
break_id()505   int break_id() { return thread_local_.break_id_; }
506 
507   // Support for embedding into generated code.
after_break_target_address()508   Address after_break_target_address() {
509     return reinterpret_cast<Address>(&after_break_target_);
510   }
511 
restarter_frame_function_pointer_address()512   Address restarter_frame_function_pointer_address() {
513     Object*** address = &thread_local_.restarter_frame_function_pointer_;
514     return reinterpret_cast<Address>(address);
515   }
516 
step_in_fp_addr()517   Address step_in_fp_addr() {
518     return reinterpret_cast<Address>(&thread_local_.step_into_fp_);
519   }
520 
521  private:
522   explicit Debug(Isolate* isolate);
523 
524   void UpdateState();
525   void Unload();
SetNextBreakId()526   void SetNextBreakId() {
527     thread_local_.break_id_ = ++thread_local_.break_count_;
528   }
529 
530   // Check whether there are commands in the command queue.
has_commands()531   inline bool has_commands() const { return !command_queue_.IsEmpty(); }
ignore_events()532   inline bool ignore_events() const { return is_suppressed_ || !is_active_; }
533 
534   // Constructors for debug event objects.
535   MUST_USE_RESULT MaybeHandle<Object> MakeJSObject(
536       const char* constructor_name,
537       int argc,
538       Handle<Object> argv[]);
539   MUST_USE_RESULT MaybeHandle<Object> MakeExecutionState();
540   MUST_USE_RESULT MaybeHandle<Object> MakeBreakEvent(
541       Handle<Object> break_points_hit);
542   MUST_USE_RESULT MaybeHandle<Object> MakeExceptionEvent(
543       Handle<Object> exception,
544       bool uncaught,
545       Handle<Object> promise);
546   MUST_USE_RESULT MaybeHandle<Object> MakeCompileEvent(
547       Handle<Script> script, bool before);
548   MUST_USE_RESULT MaybeHandle<Object> MakeScriptCollectedEvent(int id);
549 
550   // Mirror cache handling.
551   void ClearMirrorCache();
552 
553   // Returns a promise if it does not have a reject handler.
554   Handle<Object> GetPromiseForUncaughtException();
555 
556   void CallEventCallback(v8::DebugEvent event,
557                          Handle<Object> exec_state,
558                          Handle<Object> event_data,
559                          v8::Debug::ClientData* client_data);
560   void ProcessDebugEvent(v8::DebugEvent event,
561                          Handle<JSObject> event_data,
562                          bool auto_continue);
563   void NotifyMessageHandler(v8::DebugEvent event,
564                             Handle<JSObject> exec_state,
565                             Handle<JSObject> event_data,
566                             bool auto_continue);
567   void InvokeMessageHandler(MessageImpl message);
568 
569   static bool CompileDebuggerScript(Isolate* isolate, int index);
570   void ClearOneShot();
571   void ActivateStepIn(StackFrame* frame);
572   void ClearStepIn();
573   void ActivateStepOut(StackFrame* frame);
574   void ClearStepNext();
575   // Returns whether the compile succeeded.
576   void RemoveDebugInfo(Handle<DebugInfo> debug_info);
577   Handle<Object> CheckBreakPoints(Handle<Object> break_point);
578   bool CheckBreakPoint(Handle<Object> break_point_object);
579 
AssertDebugContext()580   inline void AssertDebugContext() {
581     ASSERT(isolate_->context() == *debug_context());
582     ASSERT(in_debug_scope());
583   }
584 
585   void ThreadInit();
586 
587   // Global handles.
588   Handle<Context> debug_context_;
589   Handle<Object> event_listener_;
590   Handle<Object> event_listener_data_;
591 
592   v8::Debug::MessageHandler message_handler_;
593 
594   static const int kQueueInitialSize = 4;
595   Semaphore command_received_;  // Signaled for each command received.
596   LockingCommandMessageQueue command_queue_;
597   LockingCommandMessageQueue event_command_queue_;
598 
599   bool is_active_;
600   bool is_suppressed_;
601   bool live_edit_enabled_;
602   bool has_break_points_;
603   bool break_disabled_;
604   bool break_on_exception_;
605   bool break_on_uncaught_exception_;
606 
607   ScriptCache* script_cache_;  // Cache of all scripts in the heap.
608   DebugInfoListNode* debug_info_list_;  // List of active debug info objects.
609 
610   // Storage location for jump when exiting debug break calls.
611   // Note that this address is not GC safe.  It should be computed immediately
612   // before returning to the DebugBreakCallHelper.
613   Address after_break_target_;
614 
615   // Per-thread data.
616   class ThreadLocal {
617    public:
618     // Top debugger entry.
619     DebugScope* current_debug_scope_;
620 
621     // Counter for generating next break id.
622     int break_count_;
623 
624     // Current break id.
625     int break_id_;
626 
627     // Frame id for the frame of the current break.
628     StackFrame::Id break_frame_id_;
629 
630     // Step action for last step performed.
631     StepAction last_step_action_;
632 
633     // Source statement position from last step next action.
634     int last_statement_position_;
635 
636     // Number of steps left to perform before debug event.
637     int step_count_;
638 
639     // Frame pointer from last step next action.
640     Address last_fp_;
641 
642     // Number of queued steps left to perform before debug event.
643     int queued_step_count_;
644 
645     // Frame pointer for frame from which step in was performed.
646     Address step_into_fp_;
647 
648     // Frame pointer for the frame where debugger should be called when current
649     // step out action is completed.
650     Address step_out_fp_;
651 
652     // Stores the way how LiveEdit has patched the stack. It is used when
653     // debugger returns control back to user script.
654     LiveEdit::FrameDropMode frame_drop_mode_;
655 
656     // When restarter frame is on stack, stores the address
657     // of the pointer to function being restarted. Otherwise (most of the time)
658     // stores NULL. This pointer is used with 'step in' implementation.
659     Object** restarter_frame_function_pointer_;
660 
661     // When a promise is being resolved, we may want to trigger a debug event
662     // if we catch a throw.  For this purpose we remember the try-catch
663     // handler address that would catch the exception.  We also hold onto a
664     // closure that returns a promise if the exception is considered uncaught.
665     // Due to the possibility of reentry we use a linked list.
666     PromiseOnStack* promise_on_stack_;
667   };
668 
669   // Storage location for registers when handling debug break calls
670   ThreadLocal thread_local_;
671 
672   Isolate* isolate_;
673 
674   friend class Isolate;
675   friend class DebugScope;
676   friend class DisableBreak;
677   friend class LiveEdit;
678   friend class SuppressDebug;
679 
680   friend Handle<FixedArray> GetDebuggedFunctions();  // In test-debug.cc
681   friend void CheckDebuggerUnloaded(bool check_functions);  // In test-debug.cc
682 
683   DISALLOW_COPY_AND_ASSIGN(Debug);
684 };
685 
686 
687 DECLARE_RUNTIME_FUNCTION(Debug_Break);
688 
689 
690 // This scope is used to load and enter the debug context and create a new
691 // break state.  Leaving the scope will restore the previous state.
692 // On failure to load, FailedToEnter returns true.
693 class DebugScope BASE_EMBEDDED {
694  public:
695   explicit DebugScope(Debug* debug);
696   ~DebugScope();
697 
698   // Check whether loading was successful.
failed()699   inline bool failed() { return failed_; }
700 
701   // Get the active context from before entering the debugger.
GetContext()702   inline Handle<Context> GetContext() { return save_.context(); }
703 
704  private:
isolate()705   Isolate* isolate() { return debug_->isolate_; }
706 
707   Debug* debug_;
708   DebugScope* prev_;               // Previous scope if entered recursively.
709   StackFrame::Id break_frame_id_;  // Previous break frame id.
710   int break_id_;                   // Previous break id.
711   bool failed_;                    // Did the debug context fail to load?
712   SaveContext save_;               // Saves previous context.
713 };
714 
715 
716 // Stack allocated class for disabling break.
717 class DisableBreak BASE_EMBEDDED {
718  public:
DisableBreak(Debug * debug,bool disable_break)719   explicit DisableBreak(Debug* debug, bool disable_break)
720     : debug_(debug), old_state_(debug->break_disabled_) {
721     debug_->break_disabled_ = disable_break;
722   }
~DisableBreak()723   ~DisableBreak() { debug_->break_disabled_ = old_state_; }
724 
725  private:
726   Debug* debug_;
727   bool old_state_;
728   DISALLOW_COPY_AND_ASSIGN(DisableBreak);
729 };
730 
731 
732 class SuppressDebug BASE_EMBEDDED {
733  public:
SuppressDebug(Debug * debug)734   explicit SuppressDebug(Debug* debug)
735       : debug_(debug), old_state_(debug->is_suppressed_) {
736     debug_->is_suppressed_ = true;
737   }
~SuppressDebug()738   ~SuppressDebug() { debug_->is_suppressed_ = old_state_; }
739 
740  private:
741   Debug* debug_;
742   bool old_state_;
743   DISALLOW_COPY_AND_ASSIGN(SuppressDebug);
744 };
745 
746 
747 // Code generator routines.
748 class DebugCodegen : public AllStatic {
749  public:
750   static void GenerateSlot(MacroAssembler* masm);
751   static void GenerateCallICStubDebugBreak(MacroAssembler* masm);
752   static void GenerateLoadICDebugBreak(MacroAssembler* masm);
753   static void GenerateStoreICDebugBreak(MacroAssembler* masm);
754   static void GenerateKeyedLoadICDebugBreak(MacroAssembler* masm);
755   static void GenerateKeyedStoreICDebugBreak(MacroAssembler* masm);
756   static void GenerateCompareNilICDebugBreak(MacroAssembler* masm);
757   static void GenerateReturnDebugBreak(MacroAssembler* masm);
758   static void GenerateCallFunctionStubDebugBreak(MacroAssembler* masm);
759   static void GenerateCallConstructStubDebugBreak(MacroAssembler* masm);
760   static void GenerateCallConstructStubRecordDebugBreak(MacroAssembler* masm);
761   static void GenerateSlotDebugBreak(MacroAssembler* masm);
762   static void GeneratePlainReturnLiveEdit(MacroAssembler* masm);
763 
764   // FrameDropper is a code replacement for a JavaScript frame with possibly
765   // several frames above.
766   // There is no calling conventions here, because it never actually gets
767   // called, it only gets returned to.
768   static void GenerateFrameDropperLiveEdit(MacroAssembler* masm);
769 };
770 
771 
772 } }  // namespace v8::internal
773 
774 #endif  // V8_DEBUG_H_
775