Debugger: ScopeMirror has N^2 algorithm when building closure mirrors. (take 2).

Review URL: https://chromiumcodereview.appspot.com/12326103
Patch from Pavel Feldman <pfeldman@chromium.org>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13724 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects.h

@@ -3559,6 +3559,13 @@ class ScopeInfo : public FixedArray {
   // must be a symbol (canonicalized).
   int FunctionContextSlotIndex(String* name, VariableMode* mode);
 
+
+  // Copies all the context locals into an object used to materialize a scope.
+  bool CopyContextLocalsToScopeObject(Isolate* isolate,
+                                      Handle<Context> context,
+                                      Handle<JSObject> scope_object);
+
+
   static Handle<ScopeInfo> Create(Scope* scope, Zone* zone);
 
   // Serializes empty scope info.

src/runtime.cc

@@ -10597,34 +10597,6 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_GetFrameDetails) {
 }
 
 
-// Copy all the context locals into an object used to materialize a scope.
-static bool CopyContextLocalsToScopeObject(
-    Isolate* isolate,
-    Handle<ScopeInfo> scope_info,
-    Handle<Context> context,
-    Handle<JSObject> scope_object) {
-  // Fill all context locals to the context extension.
-  for (int i = 0; i < scope_info->ContextLocalCount(); i++) {
-    VariableMode mode;
-    InitializationFlag init_flag;
-    int context_index = scope_info->ContextSlotIndex(
-        scope_info->ContextLocalName(i), &mode, &init_flag);
-
-    RETURN_IF_EMPTY_HANDLE_VALUE(
-        isolate,
-        SetProperty(isolate,
-                    scope_object,
-                    Handle<String>(scope_info->ContextLocalName(i)),
-                    Handle<Object>(context->get(context_index), isolate),
-                    NONE,
-                    kNonStrictMode),
-        false);
-  }
-
-  return true;
-}
-
-
 // Create a plain JSObject which materializes the local scope for the specified
 // frame.
 static Handle<JSObject> MaterializeLocalScopeWithFrameInspector(
@@ -10675,8 +10647,8 @@ static Handle<JSObject> MaterializeLocalScopeWithFrameInspector(
     // Third fill all context locals.
     Handle<Context> frame_context(Context::cast(frame->context()));
     Handle<Context> function_context(frame_context->declaration_context());
-    if (!CopyContextLocalsToScopeObject(
-            isolate, scope_info, function_context, local_scope)) {
+    if (!scope_info->CopyContextLocalsToScopeObject(
+            isolate, function_context, local_scope)) {
       return Handle<JSObject>();
     }
 
@@ -10828,8 +10800,8 @@ static Handle<JSObject> MaterializeClosure(Isolate* isolate,
       isolate->factory()->NewJSObject(isolate->object_function());
 
   // Fill all context locals to the context extension.
-  if (!CopyContextLocalsToScopeObject(
-          isolate, scope_info, context, closure_scope)) {
+  if (!scope_info->CopyContextLocalsToScopeObject(
+          isolate, context, closure_scope)) {
     return Handle<JSObject>();
   }
 
@@ -10949,8 +10921,8 @@ static Handle<JSObject> MaterializeBlockScope(
       isolate->factory()->NewJSObject(isolate->object_function());
 
   // Fill all context locals.
-  if (!CopyContextLocalsToScopeObject(
-          isolate, scope_info, context, block_scope)) {
+  if (!scope_info->CopyContextLocalsToScopeObject(
+          isolate, context, block_scope)) {
     return Handle<JSObject>();
   }
 
@@ -10972,8 +10944,8 @@ static Handle<JSObject> MaterializeModuleScope(
       isolate->factory()->NewJSObject(isolate->object_function());
 
   // Fill all context locals.
-  if (!CopyContextLocalsToScopeObject(
-          isolate, scope_info, context, module_scope)) {
+  if (!scope_info->CopyContextLocalsToScopeObject(
+          isolate, context, module_scope)) {
     return Handle<JSObject>();
   }
 

src/scopeinfo.cc

@@ -362,6 +362,31 @@ int ScopeInfo::FunctionContextSlotIndex(String* name, VariableMode* mode) {
 }
 
 
+bool ScopeInfo::CopyContextLocalsToScopeObject(
+    Isolate* isolate,
+    Handle<Context> context,
+    Handle<JSObject> scope_object) {
+  int local_count = ContextLocalCount();
+  if (local_count == 0) return true;
+  // Fill all context locals to the context extension.
+  int start = ContextLocalNameEntriesIndex();
+  int end = start + local_count;
+  for (int i = start; i < end; ++i) {
+    int context_index = Context::MIN_CONTEXT_SLOTS + i - start;
+    RETURN_IF_EMPTY_HANDLE_VALUE(
+        isolate,
+        SetProperty(isolate,
+                    scope_object,
+                    Handle<String>(String::cast(get(i))),
+                    Handle<Object>(context->get(context_index), isolate),
+                    ::NONE,
+                    kNonStrictMode),
+        false);
+  }
+  return true;
+}
+
+
 int ScopeInfo::ParameterEntriesIndex() {
   ASSERT(length() > 0);
   return kVariablePartIndex;