Debugger: do not hold onto debug infos weakly.

SharedFunctionInfos that have a debug info must not be collected.
Otherwise we lose previously set break points. This means that
there is no need to hold onto debug infos weakly. The reason this
has not caused an issue up till now is that code flushing has been
disabled when the debugger is active.

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/1255793003

Cr-Commit-Position: refs/heads/master@{#29869}

src/debug.cc

@@ -414,36 +414,15 @@ ScriptCache::~ScriptCache() {
 }
 
 
-void Debug::HandlePhantomDebugInfo(
-    const v8::WeakCallbackInfo<DebugInfoListNode>& data) {
-  DebugInfoListNode* node = data.GetParameter();
-  node->ClearInfo();
-  Debug* debug = reinterpret_cast<Isolate*>(data.GetIsolate())->debug();
-  debug->RemoveDebugInfo(node);
-#ifdef DEBUG
-  for (DebugInfoListNode* n = debug->debug_info_list_;
-       n != NULL;
-       n = n->next()) {
-    DCHECK(n != node);
-  }
-#endif
-}
-
-
 DebugInfoListNode::DebugInfoListNode(DebugInfo* debug_info): next_(NULL) {
   // Globalize the request debug info object and make it weak.
   GlobalHandles* global_handles = debug_info->GetIsolate()->global_handles();
   debug_info_ =
       Handle<DebugInfo>::cast(global_handles->Create(debug_info)).location();
-  typedef WeakCallbackInfo<void>::Callback Callback;
-  GlobalHandles::MakeWeak(
-      reinterpret_cast<Object**>(debug_info_), this,
-      reinterpret_cast<Callback>(Debug::HandlePhantomDebugInfo),
-      v8::WeakCallbackType::kParameter);
 }
 
 
-void DebugInfoListNode::ClearInfo() {
+DebugInfoListNode::~DebugInfoListNode() {
   if (debug_info_ == nullptr) return;
   GlobalHandles::Destroy(reinterpret_cast<Object**>(debug_info_));
   debug_info_ = nullptr;
@@ -1654,60 +1633,32 @@ bool Debug::EnsureDebugInfo(Handle<SharedFunctionInfo> shared,
 }
 
 
-void Debug::RemoveDebugInfo(DebugInfoListNode* prev, DebugInfoListNode* node) {
-  // Unlink from list. If prev is NULL we are looking at the first element.
-  if (prev == NULL) {
-    debug_info_list_ = node->next();
-  } else {
-    prev->set_next(node->next());
-  }
-  delete node;
-}
-
+void Debug::RemoveDebugInfoAndClearFromShared(Handle<DebugInfo> debug_info) {
+  HandleScope scope(isolate_);
+  Handle<SharedFunctionInfo> shared(debug_info->shared());
 
-void Debug::RemoveDebugInfo(DebugInfo** debug_info) {
-  DCHECK(debug_info_list_ != NULL);
+  DCHECK_NOT_NULL(debug_info_list_);
   // Run through the debug info objects to find this one and remove it.
   DebugInfoListNode* prev = NULL;
   DebugInfoListNode* current = debug_info_list_;
   while (current != NULL) {
-    if (current->debug_info().location() == debug_info) {
-      RemoveDebugInfo(prev, current);
-      return;
-    }
-    // Move to next in list.
-    prev = current;
-    current = current->next();
+    if (current->debug_info().is_identical_to(debug_info)) {
+      // Unlink from list. If prev is NULL we are looking at the first element.
+      if (prev == NULL) {
+        debug_info_list_ = current->next();
+      } else {
+        prev->set_next(current->next());
       }
-  UNREACHABLE();
-}
-
-
-void Debug::RemoveDebugInfo(DebugInfoListNode* node) {
-  DCHECK(debug_info_list_ != NULL);
-  // Run through the debug info objects to find this one and remove it.
-  DebugInfoListNode* prev = NULL;
-  DebugInfoListNode* current = debug_info_list_;
-  while (current != NULL) {
-    if (current == node) {
-      RemoveDebugInfo(prev, node);
+      delete current;
+      shared->set_debug_info(isolate_->heap()->undefined_value());
       return;
     }
     // Move to next in list.
     prev = current;
     current = current->next();
   }
-  UNREACHABLE();
-}
-
-
-void Debug::RemoveDebugInfoAndClearFromShared(Handle<DebugInfo> debug_info) {
-  HandleScope scope(isolate_);
-  Handle<SharedFunctionInfo> shared(debug_info->shared());
-
-  RemoveDebugInfo(debug_info.location());
 
-  shared->set_debug_info(isolate_->heap()->undefined_value());
+  UNREACHABLE();
 }
 
 

src/debug.h

@@ -214,14 +214,12 @@ class ScriptCache {
 class DebugInfoListNode {
  public:
   explicit DebugInfoListNode(DebugInfo* debug_info);
-  virtual ~DebugInfoListNode() { ClearInfo(); }
+  ~DebugInfoListNode();
 
   DebugInfoListNode* next() { return next_; }
   void set_next(DebugInfoListNode* next) { next_ = next; }
   Handle<DebugInfo> debug_info() { return Handle<DebugInfo>(debug_info_); }
 
-  void ClearInfo();
-
  private:
   // Global (weak) handle to the debug info object.
   DebugInfo** debug_info_;
@@ -476,10 +474,6 @@ class Debug {
                              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);
@@ -600,9 +594,6 @@ class Debug {
   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);