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// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_DEBUG_H_
#define V8_DEBUG_H_
#include "src/allocation.h"
#include "src/arguments.h"
#include "src/assembler.h"
#include "src/base/atomicops.h"
#include "src/base/platform/platform.h"
#include "src/execution.h"
#include "src/factory.h"
#include "src/flags.h"
#include "src/frames-inl.h"
#include "src/hashmap.h"
#include "src/liveedit.h"
#include "src/string-stream.h"
#include "src/v8threads.h"
#include "include/v8-debug.h"
namespace v8 {
namespace internal {
// Forward declarations.
class DebugScope;
// Step actions. NOTE: These values are in as well.
enum StepAction {
StepNone = -1, // Stepping not prepared.
StepOut = 0, // Step out of the current function.
StepNext = 1, // Step to the next statement in the current function.
StepIn = 2, // Step into new functions invoked or the next statement
// in the current function.
StepMin = 3, // Perform a minimum step in the current function.
StepInMin = 4, // Step into new functions invoked or perform a minimum step
// in the current function.
StepFrame = 5 // Step into a new frame or return to previous frame.
// Type of exception break. NOTE: These values are in as well.
enum ExceptionBreakType {
BreakException = 0,
BreakUncaughtException = 1
// Type of exception break.
enum BreakLocatorType {
// The different types of breakpoint position alignments.
// Must match Debug.BreakPositionAlignment in debug-debugger.js
enum BreakPositionAlignment {
// Class for iterating through the break points in a function and changing
// them.
class BreakLocationIterator {
explicit BreakLocationIterator(Handle<DebugInfo> debug_info,
BreakLocatorType type);
virtual ~BreakLocationIterator();
void Next();
void Next(int count);
void FindBreakLocationFromAddress(Address pc);
void FindBreakLocationFromPosition(int position,
BreakPositionAlignment alignment);
void Reset();
bool Done() const;
void SetBreakPoint(Handle<Object> break_point_object);
void ClearBreakPoint(Handle<Object> break_point_object);
void SetOneShot();
void ClearOneShot();
bool IsStepInLocation(Isolate* isolate);
void PrepareStepIn(Isolate* isolate);
bool IsExit() const;
bool HasBreakPoint();
bool IsDebugBreak();
Object* BreakPointObjects();
void ClearAllDebugBreak();
inline int code_position() {
return static_cast<int>(pc() - debug_info_->code()->entry());
inline int break_point() { return break_point_; }
inline int position() { return position_; }
inline int statement_position() { return statement_position_; }
inline Address pc() { return reloc_iterator_->rinfo()->pc(); }
inline Code* code() { return debug_info_->code(); }
inline RelocInfo* rinfo() { return reloc_iterator_->rinfo(); }
inline RelocInfo::Mode rmode() const {
return reloc_iterator_->rinfo()->rmode();
inline RelocInfo* original_rinfo() {
return reloc_iterator_original_->rinfo();
inline RelocInfo::Mode original_rmode() const {
return reloc_iterator_original_->rinfo()->rmode();
bool IsDebuggerStatement();
bool RinfoDone() const;
void RinfoNext();
BreakLocatorType type_;
int break_point_;
int position_;
int statement_position_;
Handle<DebugInfo> debug_info_;
RelocIterator* reloc_iterator_;
RelocIterator* reloc_iterator_original_;
void SetDebugBreak();
void ClearDebugBreak();
void SetDebugBreakAtIC();
void ClearDebugBreakAtIC();
bool IsDebugBreakAtReturn();
void SetDebugBreakAtReturn();
void ClearDebugBreakAtReturn();
bool IsDebugBreakSlot();
bool IsDebugBreakAtSlot();
void SetDebugBreakAtSlot();
void ClearDebugBreakAtSlot();
// Cache of all script objects in the heap. When a script is added a weak handle
// to it is created and that weak handle is stored in the cache. The weak handle
// callback takes care of removing the script from the cache. The key used in
// the cache is the script id.
class ScriptCache : private HashMap {
explicit ScriptCache(Isolate* isolate);
virtual ~ScriptCache() { Clear(); }
// Add script to the cache.
void Add(Handle<Script> script);
// Return the scripts in the cache.
Handle<FixedArray> GetScripts();
// Calculate the hash value from the key (script id).
static uint32_t Hash(int key) {
return ComputeIntegerHash(key, v8::internal::kZeroHashSeed);
// Clear the cache releasing all the weak handles.
void Clear();
// Weak handle callback for scripts in the cache.
static void HandleWeakScript(
const v8::WeakCallbackData<v8::Value, void>& data);
Isolate* isolate_;
// Linked list holding debug info objects. The debug info objects are kept as
// weak handles to avoid a debug info object to keep a function alive.
class DebugInfoListNode {
explicit DebugInfoListNode(DebugInfo* debug_info);
virtual ~DebugInfoListNode();
DebugInfoListNode* next() { return next_; }
void set_next(DebugInfoListNode* next) { next_ = next; }
Handle<DebugInfo> debug_info() { return debug_info_; }
// Global (weak) handle to the debug info object.
Handle<DebugInfo> debug_info_;
// Next pointer for linked list.
DebugInfoListNode* next_;
// Message delivered to the message handler callback. This is either a debugger
// event or the response to a command.
class MessageImpl: public v8::Debug::Message {
// Create a message object for a debug event.
static MessageImpl NewEvent(DebugEvent event,
bool running,
Handle<JSObject> exec_state,
Handle<JSObject> event_data);
// Create a message object for the response to a debug command.
static MessageImpl NewResponse(DebugEvent event,
bool running,
Handle<JSObject> exec_state,
Handle<JSObject> event_data,
Handle<String> response_json,
v8::Debug::ClientData* client_data);
// Implementation of interface v8::Debug::Message.
virtual bool IsEvent() const;
virtual bool IsResponse() const;
virtual DebugEvent GetEvent() const;
virtual bool WillStartRunning() const;
virtual v8::Handle<v8::Object> GetExecutionState() const;
virtual v8::Handle<v8::Object> GetEventData() const;
virtual v8::Handle<v8::String> GetJSON() const;
virtual v8::Handle<v8::Context> GetEventContext() const;
virtual v8::Debug::ClientData* GetClientData() const;
virtual v8::Isolate* GetIsolate() const;
MessageImpl(bool is_event,
DebugEvent event,
bool running,
Handle<JSObject> exec_state,
Handle<JSObject> event_data,
Handle<String> response_json,
v8::Debug::ClientData* client_data);
bool is_event_; // Does this message represent a debug event?
DebugEvent event_; // Debug event causing the break.
bool running_; // Will the VM start running after this event?
Handle<JSObject> exec_state_; // Current execution state.
Handle<JSObject> event_data_; // Data associated with the event.
Handle<String> response_json_; // Response JSON if message holds a response.
v8::Debug::ClientData* client_data_; // Client data passed with the request.
// Details of the debug event delivered to the debug event listener.
class EventDetailsImpl : public v8::Debug::EventDetails {
EventDetailsImpl(DebugEvent event,
Handle<JSObject> exec_state,
Handle<JSObject> event_data,
Handle<Object> callback_data,
v8::Debug::ClientData* client_data);
virtual DebugEvent GetEvent() const;
virtual v8::Handle<v8::Object> GetExecutionState() const;
virtual v8::Handle<v8::Object> GetEventData() const;
virtual v8::Handle<v8::Context> GetEventContext() const;
virtual v8::Handle<v8::Value> GetCallbackData() const;
virtual v8::Debug::ClientData* GetClientData() const;
DebugEvent event_; // Debug event causing the break.
Handle<JSObject> exec_state_; // Current execution state.
Handle<JSObject> event_data_; // Data associated with the event.
Handle<Object> callback_data_; // User data passed with the callback
// when it was registered.
v8::Debug::ClientData* client_data_; // Data passed to DebugBreakForCommand.
// Message send by user to v8 debugger or debugger output message.
// In addition to command text it may contain a pointer to some user data
// which are expected to be passed along with the command reponse to message
// handler.
class CommandMessage {
static CommandMessage New(const Vector<uint16_t>& command,
v8::Debug::ClientData* data);
// Deletes user data and disposes of the text.
void Dispose();
Vector<uint16_t> text() const { return text_; }
v8::Debug::ClientData* client_data() const { return client_data_; }
CommandMessage(const Vector<uint16_t>& text,
v8::Debug::ClientData* data);
Vector<uint16_t> text_;
v8::Debug::ClientData* client_data_;
// A Queue of CommandMessage objects. A thread-safe version is
// LockingCommandMessageQueue, based on this class.
class CommandMessageQueue BASE_EMBEDDED {
explicit CommandMessageQueue(int size);
bool IsEmpty() const { return start_ == end_; }
CommandMessage Get();
void Put(const CommandMessage& message);
void Clear() { start_ = end_ = 0; } // Queue is empty after Clear().
// Doubles the size of the message queue, and copies the messages.
void Expand();
CommandMessage* messages_;
int start_;
int end_;
int size_; // The size of the queue buffer. Queue can hold size-1 messages.
// LockingCommandMessageQueue is a thread-safe circular buffer of CommandMessage
// messages. The message data is not managed by LockingCommandMessageQueue.
// Pointers to the data are passed in and out. Implemented by adding a
// Mutex to CommandMessageQueue. Includes logging of all puts and gets.
class LockingCommandMessageQueue BASE_EMBEDDED {
LockingCommandMessageQueue(Logger* logger, int size);
bool IsEmpty() const;
CommandMessage Get();
void Put(const CommandMessage& message);
void Clear();
Logger* logger_;
CommandMessageQueue queue_;
mutable base::Mutex mutex_;
// This class contains the debugger support. The main purpose is to handle
// setting break points in the code.
// This class controls the debug info for all functions which currently have
// active breakpoints in them. This debug info is held in the heap root object
// debug_info which is a FixedArray. Each entry in this list is of class
// DebugInfo.
class Debug {
// Debug event triggers.
void OnDebugBreak(Handle<Object> break_points_hit, bool auto_continue);
void OnThrow(Handle<Object> exception, bool uncaught);
void OnPromiseReject(Handle<JSObject> promise, Handle<Object> value);
void OnCompileError(Handle<Script> script);
void OnBeforeCompile(Handle<Script> script);
void OnAfterCompile(Handle<Script> script);
void OnPromiseEvent(Handle<JSObject> data);
void OnAsyncTaskEvent(Handle<JSObject> data);
// API facing.
void SetEventListener(Handle<Object> callback, Handle<Object> data);
void SetMessageHandler(v8::Debug::MessageHandler handler);
void EnqueueCommandMessage(Vector<const uint16_t> command,
v8::Debug::ClientData* client_data = NULL);
// Enqueue a debugger command to the command queue for event listeners.
void EnqueueDebugCommand(v8::Debug::ClientData* client_data = NULL);
MUST_USE_RESULT MaybeHandle<Object> Call(Handle<JSFunction> fun,
Handle<Object> data);
Handle<Context> GetDebugContext();
void HandleDebugBreak();
void ProcessDebugMessages(bool debug_command_only);
// Internal logic
bool Load();
void Break(Arguments args, JavaScriptFrame*);
void SetAfterBreakTarget(JavaScriptFrame* frame);
// Scripts handling.
Handle<FixedArray> GetLoadedScripts();
// Break point handling.
bool SetBreakPoint(Handle<JSFunction> function,
Handle<Object> break_point_object,
int* source_position);
bool SetBreakPointForScript(Handle<Script> script,
Handle<Object> break_point_object,
int* source_position,
BreakPositionAlignment alignment);
void ClearBreakPoint(Handle<Object> break_point_object);
void ClearAllBreakPoints();
void FloodWithOneShot(Handle<JSFunction> function,
BreakLocatorType type = ALL_BREAK_LOCATIONS);
void FloodBoundFunctionWithOneShot(Handle<JSFunction> function);
void FloodDefaultConstructorWithOneShot(Handle<JSFunction> function);
void FloodWithOneShotGeneric(Handle<JSFunction> function,
Handle<Object> holder = Handle<Object>());
void FloodHandlerWithOneShot();
void ChangeBreakOnException(ExceptionBreakType type, bool enable);
bool IsBreakOnException(ExceptionBreakType type);
// Stepping handling.
void PrepareStep(StepAction step_action,
int step_count,
StackFrame::Id frame_id);
void ClearStepping();
void ClearStepOut();
bool IsStepping() { return thread_local_.step_count_ > 0; }
bool StepNextContinue(BreakLocationIterator* break_location_iterator,
JavaScriptFrame* frame);
bool StepInActive() { return thread_local_.step_into_fp_ != 0; }
void HandleStepIn(Handle<Object> function_obj, Handle<Object> holder,
Address fp, bool is_constructor);
bool StepOutActive() { return thread_local_.step_out_fp_ != 0; }
// Purge all code objects that have no debug break slots.
void PrepareForBreakPoints();
// Returns whether the operation succeeded. Compilation can only be triggered
// if a valid closure is passed as the second argument, otherwise the shared
// function needs to be compiled already.
bool EnsureDebugInfo(Handle<SharedFunctionInfo> shared,
Handle<JSFunction> function);
static Handle<DebugInfo> GetDebugInfo(Handle<SharedFunctionInfo> shared);
static bool HasDebugInfo(Handle<SharedFunctionInfo> shared);
// This function is used in FunctionNameUsing* tests.
Object* FindSharedFunctionInfoInScript(Handle<Script> script, int position);
// Returns true if the current stub call is patched to call the debugger.
static bool IsDebugBreak(Address addr);
// Returns true if the current return statement has been patched to be
// a debugger breakpoint.
static bool IsDebugBreakAtReturn(RelocInfo* rinfo);
static Handle<Object> GetSourceBreakLocations(
Handle<SharedFunctionInfo> shared,
BreakPositionAlignment position_aligment);
// Check whether a global object is the debug global object.
bool IsDebugGlobal(GlobalObject* global);
// Check whether this frame is just about to return.
bool IsBreakAtReturn(JavaScriptFrame* frame);
// Support for LiveEdit
void FramesHaveBeenDropped(StackFrame::Id new_break_frame_id,
LiveEdit::FrameDropMode mode,
Object** restarter_frame_function_pointer);
// Passed to MakeWeak.
static void HandlePhantomDebugInfo(
const PhantomCallbackData<DebugInfoListNode>& data);
// Threading support.
char* ArchiveDebug(char* to);
char* RestoreDebug(char* from);
static int ArchiveSpacePerThread();
void FreeThreadResources() { }
// Record function from which eval was called.
static void RecordEvalCaller(Handle<Script> script);
bool CheckExecutionState(int id) {
return !debug_context().is_null() && break_id() != 0 && break_id() == id;
// Flags and states.
DebugScope* debugger_entry() {
return reinterpret_cast<DebugScope*>(
inline Handle<Context> debug_context() { return debug_context_; }
void set_live_edit_enabled(bool v) { live_edit_enabled_ = v; }
bool live_edit_enabled() const {
return FLAG_enable_liveedit && live_edit_enabled_ ;
inline bool is_active() const { return is_active_; }
inline bool is_loaded() const { return !debug_context_.is_null(); }
inline bool has_break_points() const { return has_break_points_; }
inline bool in_debug_scope() const {
return !!base::NoBarrier_Load(&thread_local_.current_debug_scope_);
void set_disable_break(bool v) { break_disabled_ = v; }
StackFrame::Id break_frame_id() { return thread_local_.break_frame_id_; }
int break_id() { return thread_local_.break_id_; }
// Support for embedding into generated code.
Address is_active_address() {
return reinterpret_cast<Address>(&is_active_);
Address after_break_target_address() {
return reinterpret_cast<Address>(&after_break_target_);
Address restarter_frame_function_pointer_address() {
Object*** address = &thread_local_.restarter_frame_function_pointer_;
return reinterpret_cast<Address>(address);
Address step_in_fp_addr() {
return reinterpret_cast<Address>(&thread_local_.step_into_fp_);
StepAction last_step_action() { return thread_local_.last_step_action_; }
explicit Debug(Isolate* isolate);
void UpdateState();
void Unload();
void SetNextBreakId() {
thread_local_.break_id_ = ++thread_local_.break_count_;
// Check whether there are commands in the command queue.
inline bool has_commands() const { return !command_queue_.IsEmpty(); }
inline bool ignore_events() const { return is_suppressed_ || !is_active_; }
inline bool break_disabled() const {
return break_disabled_ || in_debug_event_listener_;
void OnException(Handle<Object> exception, bool uncaught,
Handle<Object> promise);
// Constructors for debug event objects.
MUST_USE_RESULT MaybeHandle<Object> MakeJSObject(
const char* constructor_name,
int argc,
Handle<Object> argv[]);
MUST_USE_RESULT MaybeHandle<Object> MakeExecutionState();
MUST_USE_RESULT MaybeHandle<Object> MakeBreakEvent(
Handle<Object> break_points_hit);
MUST_USE_RESULT MaybeHandle<Object> MakeExceptionEvent(
Handle<Object> exception,
bool uncaught,
Handle<Object> promise);
MUST_USE_RESULT MaybeHandle<Object> MakeCompileEvent(
Handle<Script> script, v8::DebugEvent type);
MUST_USE_RESULT MaybeHandle<Object> MakePromiseEvent(
Handle<JSObject> promise_event);
MUST_USE_RESULT MaybeHandle<Object> MakeAsyncTaskEvent(
Handle<JSObject> task_event);
// Mirror cache handling.
void ClearMirrorCache();
MaybeHandle<Object> PromiseHasUserDefinedRejectHandler(
Handle<JSObject> promise);
void CallEventCallback(v8::DebugEvent event,
Handle<Object> exec_state,
Handle<Object> event_data,
v8::Debug::ClientData* client_data);
void ProcessCompileEventInDebugScope(v8::DebugEvent event,
Handle<Script> script);
void ProcessDebugEvent(v8::DebugEvent event,
Handle<JSObject> event_data,
bool auto_continue);
void NotifyMessageHandler(v8::DebugEvent event,
Handle<JSObject> exec_state,
Handle<JSObject> event_data,
bool auto_continue);
void InvokeMessageHandler(MessageImpl message);
static bool CompileDebuggerScript(Isolate* isolate, int index);
void ClearOneShot();
void ActivateStepIn(StackFrame* frame);
void ClearStepIn();
void ActivateStepOut(StackFrame* frame);
void ClearStepNext();
void RemoveDebugInfoAndClearFromShared(Handle<DebugInfo> debug_info);
void RemoveDebugInfo(DebugInfo** debug_info);
void RemoveDebugInfo(DebugInfoListNode* node);
void RemoveDebugInfo(DebugInfoListNode* prev, DebugInfoListNode* node);
Handle<Object> CheckBreakPoints(Handle<Object> break_point);
bool CheckBreakPoint(Handle<Object> break_point_object);
inline void AssertDebugContext() {
DCHECK(isolate_->context() == *debug_context());
void ThreadInit();
// Global handles.
Handle<Context> debug_context_;
Handle<Object> event_listener_;
Handle<Object> event_listener_data_;
v8::Debug::MessageHandler message_handler_;
static const int kQueueInitialSize = 4;
base::Semaphore command_received_; // Signaled for each command received.
LockingCommandMessageQueue command_queue_;
LockingCommandMessageQueue event_command_queue_;
bool is_active_;
bool is_suppressed_;
bool live_edit_enabled_;
bool has_break_points_;
bool break_disabled_;
bool in_debug_event_listener_;
bool break_on_exception_;
bool break_on_uncaught_exception_;
ScriptCache* script_cache_; // Cache of all scripts in the heap.
DebugInfoListNode* debug_info_list_; // List of active debug info objects.
// Storage location for jump when exiting debug break calls.
// Note that this address is not GC safe. It should be computed immediately
// before returning to the DebugBreakCallHelper.
Address after_break_target_;
// Per-thread data.
class ThreadLocal {
// Top debugger entry.
base::AtomicWord current_debug_scope_;
// Counter for generating next break id.
int break_count_;
// Current break id.
int break_id_;
// Frame id for the frame of the current break.
StackFrame::Id break_frame_id_;
// Step action for last step performed.
StepAction last_step_action_;
// Source statement position from last step next action.
int last_statement_position_;
// Number of steps left to perform before debug event.
int step_count_;
// Frame pointer from last step next or step frame action.
Address last_fp_;
// Number of queued steps left to perform before debug event.
int queued_step_count_;
// Frame pointer for frame from which step in was performed.
Address step_into_fp_;
// Frame pointer for the frame where debugger should be called when current
// step out action is completed.
Address step_out_fp_;
// Stores the way how LiveEdit has patched the stack. It is used when
// debugger returns control back to user script.
LiveEdit::FrameDropMode frame_drop_mode_;
// When restarter frame is on stack, stores the address
// of the pointer to function being restarted. Otherwise (most of the time)
// stores NULL. This pointer is used with 'step in' implementation.
Object** restarter_frame_function_pointer_;
// Storage location for registers when handling debug break calls
ThreadLocal thread_local_;
Isolate* isolate_;
friend class Isolate;
friend class DebugScope;
friend class DisableBreak;
friend class LiveEdit;
friend class SuppressDebug;
friend Handle<FixedArray> GetDebuggedFunctions(); // In
friend void CheckDebuggerUnloaded(bool check_functions); // In
// This scope is used to load and enter the debug context and create a new
// break state. Leaving the scope will restore the previous state.
// On failure to load, FailedToEnter returns true.
class DebugScope BASE_EMBEDDED {
explicit DebugScope(Debug* debug);
// Check whether loading was successful.
inline bool failed() { return failed_; }
// Get the active context from before entering the debugger.
inline Handle<Context> GetContext() { return save_.context(); }
Isolate* isolate() { return debug_->isolate_; }
Debug* debug_;
DebugScope* prev_; // Previous scope if entered recursively.
StackFrame::Id break_frame_id_; // Previous break frame id.
int break_id_; // Previous break id.
bool failed_; // Did the debug context fail to load?
SaveContext save_; // Saves previous context.
PostponeInterruptsScope no_termination_exceptons_;
// Stack allocated class for disabling break.
class DisableBreak BASE_EMBEDDED {
explicit DisableBreak(Debug* debug, bool disable_break)
: debug_(debug),
previous_in_debug_event_listener_(debug->in_debug_event_listener_) {
debug_->break_disabled_ = disable_break;
debug_->in_debug_event_listener_ = disable_break;
~DisableBreak() {
debug_->break_disabled_ = previous_break_disabled_;
debug_->in_debug_event_listener_ = previous_in_debug_event_listener_;
Debug* debug_;
bool previous_break_disabled_;
bool previous_in_debug_event_listener_;
class SuppressDebug BASE_EMBEDDED {
explicit SuppressDebug(Debug* debug)
: debug_(debug), old_state_(debug->is_suppressed_) {
debug_->is_suppressed_ = true;
~SuppressDebug() { debug_->is_suppressed_ = old_state_; }
Debug* debug_;
bool old_state_;
// Code generator routines.
class DebugCodegen : public AllStatic {
static void GenerateSlot(MacroAssembler* masm);
static void GenerateCallICStubDebugBreak(MacroAssembler* masm);
static void GenerateLoadICDebugBreak(MacroAssembler* masm);
static void GenerateStoreICDebugBreak(MacroAssembler* masm);
static void GenerateKeyedLoadICDebugBreak(MacroAssembler* masm);
static void GenerateKeyedStoreICDebugBreak(MacroAssembler* masm);
static void GenerateCompareNilICDebugBreak(MacroAssembler* masm);
static void GenerateReturnDebugBreak(MacroAssembler* masm);
static void GenerateCallFunctionStubDebugBreak(MacroAssembler* masm);
static void GenerateCallConstructStubDebugBreak(MacroAssembler* masm);
static void GenerateCallConstructStubRecordDebugBreak(MacroAssembler* masm);
static void GenerateSlotDebugBreak(MacroAssembler* masm);
static void GeneratePlainReturnLiveEdit(MacroAssembler* masm);
// FrameDropper is a code replacement for a JavaScript frame with possibly
// several frames above.
// There is no calling conventions here, because it never actually gets
// called, it only gets returned to.
static void GenerateFrameDropperLiveEdit(MacroAssembler* masm);
} } // namespace v8::internal
#endif // V8_DEBUG_H_