Introduce scopes to keep track of catch blocks at compile time.

src/runtime.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 10041 matching lines @@
     locals->set(i * 2, *info.LocalName(i));
     if (it.frame()->is_optimized()) {
       // Get the value from the deoptimized frame.
       locals->set(i * 2 + 1,
                   deoptimized_frame->GetExpression(i));
     } else {
       // Get the value from the stack.
       locals->set(i * 2 + 1, it.frame()->GetExpression(i));
     }
   }
-  // Get the context containing declarations.
-  Handle<Context> context(
-      Context::cast(it.frame()->context())->declaration_context());
-  for (; i < info.NumberOfLocals(); ++i) {
-    Handle<String> name = info.LocalName(i);
-    locals->set(i * 2, *name);
-    locals->set(i * 2 + 1,
-                context->get(scope_info->ContextSlotIndex(*name, NULL)));
+  if (i < info.NumberOfLocals()) {
+    // Get the context containing declarations.
+    Handle<Context> context(
+        Context::cast(it.frame()->context())->declaration_context());
+    for (; i < info.NumberOfLocals(); ++i) {
+      Handle<String> name = info.LocalName(i);
+      locals->set(i * 2, *name);
+      locals->set(i * 2 + 1,
+                  context->get(scope_info->ContextSlotIndex(*name, NULL)));
+    }
   }
 
   // Check whether this frame is positioned at return. If not top
   // frame or if the frame is optimized it cannot be at a return.
   bool at_return = false;
   if (!it.frame()->is_optimized() && index == 0) {
     at_return = isolate->debug()->IsBreakAtReturn(it.frame());
   }
 
   // If positioned just before return find the value to be returned and add it
@@ skipping 201 matching lines @@
         isolate,
         SetProperty(local_scope,
                     scope_info.parameter_name(i),
                     Handle<Object>(frame->GetParameter(i), isolate),
                     NONE,
                     kNonStrictMode),
         Handle<JSObject>());
   }
 
   // Second fill all stack locals.
-  for (int i = 0; i < scope_info.number_of_stack_slots(); i++) {
+  for (int i = 0; i < scope_info.number_of_stack_slots(); ++i) {
     RETURN_IF_EMPTY_HANDLE_VALUE(
         isolate,
         SetProperty(local_scope,
                     scope_info.stack_slot_name(i),
                     Handle<Object>(frame->GetExpression(i), isolate),
                     NONE,
                     kNonStrictMode),
         Handle<JSObject>());
   }
 
-  // Third fill all context locals.
-  Handle<Context> frame_context(Context::cast(frame->context()));
-  Handle<Context> function_context(frame_context->declaration_context());
-  if (!CopyContextLocalsToScopeObject(isolate,
-                                      serialized_scope_info, scope_info,
-                                      function_context, local_scope)) {
-    return Handle<JSObject>();
-  }
+  if (scope_info.number_of_context_slots() > Context::MIN_CONTEXT_SLOTS) {
+    // Third fill all context locals.
+    Handle<Context> frame_context(Context::cast(frame->context()));
+    Handle<Context> function_context(frame_context->declaration_context());
+    if (!CopyContextLocalsToScopeObject(isolate,
+                                        serialized_scope_info, scope_info,
+                                        function_context, local_scope)) {
+      return Handle<JSObject>();
+    }
 
-  // Finally copy any properties from the function context extension. This will
-  // be variables introduced by eval.
-  if (function_context->closure() == *function) {
-    if (function_context->has_extension() &&
-        !function_context->IsGlobalContext()) {
-      Handle<JSObject> ext(JSObject::cast(function_context->extension()));
-      Handle<FixedArray> keys = GetKeysInFixedArrayFor(ext, INCLUDE_PROTOS);
-      for (int i = 0; i < keys->length(); i++) {
-        // Names of variables introduced by eval are strings.
-        ASSERT(keys->get(i)->IsString());
-        Handle<String> key(String::cast(keys->get(i)));
-        RETURN_IF_EMPTY_HANDLE_VALUE(
-            isolate,
-            SetProperty(local_scope,
-                        key,
-                        GetProperty(ext, key),
-                        NONE,
-                        kNonStrictMode),
-            Handle<JSObject>());
+    // Finally copy any properties from the function context extension. This will

[Kevin Millikin (Chromium), 2011/06/30 09:28:45]

Long line already fixed.

+    // be variables introduced by eval.
+    if (function_context->closure() == *function) {
+      if (function_context->has_extension() &&
+          !function_context->IsGlobalContext()) {
+        Handle<JSObject> ext(JSObject::cast(function_context->extension()));
+        Handle<FixedArray> keys = GetKeysInFixedArrayFor(ext, INCLUDE_PROTOS);
+        for (int i = 0; i < keys->length(); i++) {
+          // Names of variables introduced by eval are strings.
+          ASSERT(keys->get(i)->IsString());
+          Handle<String> key(String::cast(keys->get(i)));
+          RETURN_IF_EMPTY_HANDLE_VALUE(
+              isolate,
+              SetProperty(local_scope,
+                          key,
+                          GetProperty(ext, key),
+                          NONE,
+                          kNonStrictMode),
+              Handle<JSObject>());
+        }
       }
     }
   }
+
   return local_scope;
 }
 
 
 // Create a plain JSObject which materializes the closure content for the
 // context.
 static Handle<JSObject> MaterializeClosure(Isolate* isolate,
                                            Handle<Context> context) {
   ASSERT(context->IsFunctionContext());
 
@@ skipping 2206 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal