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

src/debug/debug.h

Index: src/debug/debug.h
diff --git a/src/debug/debug.h b/src/debug/debug.h
index e87e8aecad1644dc19e5da283942a83c37f6a8fd..4b0ae1be1c9c105112207fe00a7c5d4ff40527dd 100644
--- a/src/debug/debug.h
+++ b/src/debug/debug.h
@@ -518,6 +518,8 @@ class Debug {
     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*>(
@@ -537,6 +539,7 @@ class Debug {
   }
   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_; }
@@ -551,6 +554,10 @@ class Debug {
     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_);
   }
@@ -571,6 +578,7 @@ class Debug {
   explicit Debug(Isolate* isolate);
 
   void UpdateState();
+  void UpdateHookOnFunctionCall();
   void Unload();
   void SetNextBreakId() {
     thread_local_.break_id_ = ++thread_local_.break_count_;
@@ -667,6 +675,7 @@ class Debug {
   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_;
@@ -674,6 +683,8 @@ class Debug {
   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.
 
@@ -733,6 +744,7 @@ class Debug {
   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
@@ -806,6 +818,21 @@ class SuppressDebug BASE_EMBEDDED {
   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 {