[debugger] infrastructure for side-effect-free debug-evaluate.

src/debug/debug.h

 // 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_DEBUG_H_
 #define V8_DEBUG_DEBUG_H_
 
 #include "src/allocation.h"
 #include "src/arguments.h"
 #include "src/assembler.h"
@@ skipping 500 matching lines @@
   void Iterate(ObjectVisitor* v);
 
   bool CheckExecutionState(int id) {
     return CheckExecutionState() && break_id() == id;
   }
 
   bool CheckExecutionState() {
     return is_active() && !debug_context().is_null() && break_id() != 0;
   }
 
+  bool PerformReadOnlyCheck(Handle<JSFunction> function);
+
   // Flags and states.
   DebugScope* debugger_entry() {
     return reinterpret_cast<DebugScope*>(
         base::NoBarrier_Load(&thread_local_.current_debug_scope_));
   }
   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 in_debug_scope() const {
     return !!base::NoBarrier_Load(&thread_local_.current_debug_scope_);
   }
   void set_break_points_active(bool v) { break_points_active_ = v; }
   bool break_points_active() const { return break_points_active_; }
+  bool needs_readonly_check() const { return needs_readonly_check_; }
 
   StackFrame::Id break_frame_id() { return thread_local_.break_frame_id_; }
   int break_id() { return thread_local_.break_id_; }
 
   Handle<Object> return_value() { return thread_local_.return_value_; }
   void set_return_value(Handle<Object> value) {
     thread_local_.return_value_ = value;
   }
 
   // Support for embedding into generated code.
   Address is_active_address() {
     return reinterpret_cast<Address>(&is_active_);
   }
 
+  Address hook_on_function_call_address() {
+    return reinterpret_cast<Address>(&hook_on_function_call_);
+  }
+
   Address after_break_target_address() {
     return reinterpret_cast<Address>(&after_break_target_);
   }
 
   Address last_step_action_address() {
     return reinterpret_cast<Address>(&thread_local_.last_step_action_);
   }
 
   Address suspended_generator_address() {
     return reinterpret_cast<Address>(&thread_local_.suspended_generator_);
   }
 
   StepAction last_step_action() { return thread_local_.last_step_action_; }
 
   DebugFeatureTracker* feature_tracker() { return &feature_tracker_; }
 
  private:
   explicit Debug(Isolate* isolate);
 
   void UpdateState();
+  void UpdateHookOnFunctionCall();
   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_;
@@ skipping 76 matching lines @@
   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_;
 
   bool is_active_;
+  bool hook_on_function_call_;

[jgruber, 2017/01/10 12:46:37]

A brief comment about what each of these new variables is used for would be
great.

[Yang, 2017/01/10 14:14:06]

Done.

   bool is_suppressed_;
   bool live_edit_enabled_;
   bool break_disabled_;
   bool break_points_active_;
   bool in_debug_event_listener_;
   bool break_on_exception_;
   bool break_on_uncaught_exception_;
+  bool needs_readonly_check_;
+  bool readonly_check_failed_;
 
   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_;
 
   // Used to collect histogram data on debugger feature usage.
   DebugFeatureTracker feature_tracker_;
@@ skipping 39 matching lines @@
   // 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 class ReadOnlyEvaluate;
 
   friend Handle<FixedArray> GetDebuggedFunctions();  // In test-debug.cc
   friend void CheckDebuggerUnloaded(bool check_functions);  // In test-debug.cc
 
   DISALLOW_COPY_AND_ASSIGN(Debug);
 };
 
 
 // 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.
@@ skipping 53 matching lines @@
     debug_->is_suppressed_ = true;
   }
   ~SuppressDebug() { debug_->is_suppressed_ = old_state_; }
 
  private:
   Debug* debug_;
   bool old_state_;
   DISALLOW_COPY_AND_ASSIGN(SuppressDebug);
 };
 
+class ReadOnlyEvaluate {

[jgruber, 2017/01/10 12:46:37]

Maybe ReadOnlyEvaluateScope?

[Yang, 2017/01/10 14:14:06]

Done.

+ public:
+  ReadOnlyEvaluate(Debug* debug, bool readonly)
+      : debug_(debug), old_state_(debug->needs_readonly_check_) {
+    debug_->needs_readonly_check_ |= readonly;
+    debug_->UpdateHookOnFunctionCall();
+    debug_->readonly_check_failed_ = false;
+  }
+  ~ReadOnlyEvaluate();
+
+ private:
+  Debug* debug_;
+  bool old_state_;

[jgruber, 2017/01/10 12:46:37]

Maybe old_needs_readonly_check_?

+  DISALLOW_COPY_AND_ASSIGN(ReadOnlyEvaluate);
+};
 
 // Code generator routines.
 class DebugCodegen : public AllStatic {
  public:
   enum DebugBreakCallHelperMode {
     SAVE_RESULT_REGISTER,
     IGNORE_RESULT_REGISTER
   };
 
   static void GenerateDebugBreakStub(MacroAssembler* masm,
@@ skipping 12 matching lines @@
                                   Handle<Code> code);
   static bool DebugBreakSlotIsPatched(Address pc);
   static void ClearDebugBreakSlot(Isolate* isolate, Address pc);
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_DEBUG_DEBUG_H_