Debugger: speed up setting break points in nested SFI.

src/debug/debug.cc

Index: src/debug/debug.cc
diff --git a/src/debug/debug.cc b/src/debug/debug.cc
index d6b4ebb62271092029783e50cdad6c6e698ea53c..9e7fc53ae8cdf8354cb1c6eb8efe565bd9212687 100644
--- a/src/debug/debug.cc
+++ b/src/debug/debug.cc
@@ -1377,6 +1377,7 @@ class SharedFunctionInfoFinder {
         target_position_(target_position) {}
 
   void NewCandidate(SharedFunctionInfo* shared, JSFunction* closure = NULL) {
+    if (!shared->IsSubjectToDebugging()) return;
     int start_position = shared->function_token_position();
     if (start_position == RelocInfo::kNoPosition) {
       start_position = shared->start_position();
@@ -1426,7 +1427,7 @@ class SharedFunctionInfoFinder {
 // cannot be compiled without context (need to find outer compilable SFI etc.)
 Handle<Object> Debug::FindSharedFunctionInfoInScript(Handle<Script> script,
                                                      int position) {
-  while (true) {
+  for (int iteration = 0;; iteration++) {
     // Go through all shared function infos associated with this script to
     // find the inner most function containing this position.
     // If there is no shared function info for this script at all, there is
@@ -1444,7 +1445,18 @@ Handle<Object> Debug::FindSharedFunctionInfoInScript(Handle<Script> script,
       shared = finder.Result();
       if (shared == NULL) break;
       // We found it if it's already compiled and has debug code.
-      if (shared->HasDebugCode()) return handle(shared);
+      if (shared->HasDebugCode()) {
+        Handle<SharedFunctionInfo> shared_handle(shared);
+        // If the iteration count is larger than 1, we had to compile the outer
+        // function in order to create this shared function info. So there can
+        // be no JSFunction referencing it. We can anticipate creating a debug
+        // info while bypassing PrepareFunctionForBreakpoints.
+        if (iteration > 1) {
+          AllowHeapAllocation allow_before_return;
+          CreateDebugInfo(shared_handle);
+        }
+        return shared_handle;
+      }
     }
     // If not, compile to reveal inner functions, if possible.
     if (shared->allows_lazy_compilation_without_context()) {
@@ -1509,6 +1521,13 @@ bool Debug::EnsureDebugInfo(Handle<SharedFunctionInfo> shared,
   shared->code()->ClearInlineCaches();
   shared->ClearTypeFeedbackInfo();
 
+  CreateDebugInfo(shared);
+
+  return true;
+}
+
+
+void Debug::CreateDebugInfo(Handle<SharedFunctionInfo> shared) {
   // Create the debug info object.
   DCHECK(shared->HasDebugCode());
   Handle<DebugInfo> debug_info = isolate_->factory()->NewDebugInfo(shared);
@@ -1517,8 +1536,6 @@ bool Debug::EnsureDebugInfo(Handle<SharedFunctionInfo> shared,
   DebugInfoListNode* node = new DebugInfoListNode(*debug_info);
   node->set_next(debug_info_list_);
   debug_info_list_ = node;
-
-  return true;
 }