[es6] Parameter scopes for sloppy eval

src/contexts.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/contexts.h"
 
 #include "src/bootstrapper.h"
 #include "src/debug/debug.h"
 #include "src/scopeinfo.h"
 
@@ skipping 23 matching lines @@
   result->set(used + 1, *script_context);
   return result;
 }
 
 
 bool ScriptContextTable::Lookup(Handle<ScriptContextTable> table,
                                 Handle<String> name, LookupResult* result) {
   for (int i = 0; i < table->used(); i++) {
     Handle<Context> context = GetContext(table, i);
     DCHECK(context->IsScriptContext());
-    Handle<ScopeInfo> scope_info(ScopeInfo::cast(context->extension()));
+    Handle<ScopeInfo> scope_info(context->scope_info());
     int slot_index = ScopeInfo::ContextSlotIndex(
         scope_info, name, &result->mode, &result->location, &result->init_flag,
         &result->maybe_assigned_flag);
 
     if (slot_index >= 0 && result->location == VariableLocation::CONTEXT) {
       result->context_index = i;
       result->slot_index = slot_index;
       return true;
     }
   }
   return false;
 }
 
 
+bool Context::is_declaration_context() {
+  if (IsFunctionContext() || IsNativeContext() || IsScriptContext()) {
+    return true;
+  }
+  if (!IsBlockContext()) return false;
+  Object* ext = extension();
+  return ext->IsSloppyBlockWithEvalContextExtension()

[Michael Starzinger, 2015/08/20 10:30:00]

nit: As discussed offline, it is not immediately clear from the code that a
block-context containing the new pair will always be a declaration scope (i.e.
that pair->scope_info()->is_declaration_scope() will always hold). Can we leave
a comment or DCHECK in that regard here?

[rossberg, 2015/08/21 10:00:39]

Done: added a comment here and a DCHECK to the factory function for
SloppyBlockWithBla itself.

+      || ScopeInfo::cast(ext)->is_declaration_scope();
+}
+
+
 Context* Context::declaration_context() {
   Context* current = this;
-  while (!current->IsFunctionContext() && !current->IsNativeContext() &&
-         !current->IsScriptContext()) {
+  while (!current->is_declaration_context()) {
     current = current->previous();
     DCHECK(current->closure() == closure());
   }
   return current;
 }
 
 
+JSObject* Context::extension_object() {
+  DCHECK(IsNativeContext() || IsFunctionContext() || IsBlockContext());
+  Object* object = extension();
+  if (object == nullptr) return nullptr;
+  if (IsBlockContext()) {
+    if (!object->IsSloppyBlockWithEvalContextExtension()) return nullptr;
+    object = SloppyBlockWithEvalContextExtension::cast(object)->extension();
+  }
+  DCHECK(object->IsJSContextExtensionObject() ||
+         (IsNativeContext() && object->IsJSGlobalObject()));
+  return JSObject::cast(object);
+}
+
+
+JSReceiver* Context::extension_receiver() {
+  DCHECK(IsNativeContext() || IsWithContext() ||
+         IsFunctionContext() || IsBlockContext());
+  return IsWithContext() ? JSReceiver::cast(extension()) : extension_object();
+}
+
+
+ScopeInfo* Context::scope_info() {
+  DCHECK(IsModuleContext() || IsScriptContext() || IsBlockContext());
+  Object* object = extension();
+  if (object->IsSloppyBlockWithEvalContextExtension()) {
+    DCHECK(IsBlockContext());
+    object = SloppyBlockWithEvalContextExtension::cast(object)->scope_info();
+  }
+  return ScopeInfo::cast(object);
+}
+
+
+String* Context::catch_name() {
+  DCHECK(IsCatchContext());
+  return String::cast(extension());
+}
+
+
 JSBuiltinsObject* Context::builtins() {
   GlobalObject* object = global_object();
   if (object->IsJSGlobalObject()) {
     return JSGlobalObject::cast(object)->builtins();
   } else {
     DCHECK(object->IsJSBuiltinsObject());
     return JSBuiltinsObject::cast(object);
   }
 }
 
@@ skipping 125 matching lines @@
   }
 
   do {
     if (FLAG_trace_contexts) {
       PrintF(" - looking in context %p", reinterpret_cast<void*>(*context));
       if (context->IsScriptContext()) PrintF(" (script context)");
       if (context->IsNativeContext()) PrintF(" (native context)");
       PrintF("\n");
     }
 
-
     // 1. Check global objects, subjects of with, and extension objects.
-    if (context->IsNativeContext() ||
-        context->IsWithContext() ||
-        (context->IsFunctionContext() && context->has_extension())) {
-      Handle<JSReceiver> object(
-          JSReceiver::cast(context->extension()), isolate);
+    if ((context->IsNativeContext() || context->IsWithContext() ||
+         context->IsFunctionContext() || context->IsBlockContext()) &&
+        context->extension_receiver() != nullptr) {
+      Handle<JSReceiver> object(context->extension_receiver());
 
       if (context->IsNativeContext()) {
         if (FLAG_trace_contexts) {
           PrintF(" - trying other script contexts\n");
         }
         // Try other script contexts.
         Handle<ScriptContextTable> script_contexts(
             context->global_object()->native_context()->script_context_table());
         ScriptContextTable::LookupResult r;
         if (ScriptContextTable::Lookup(script_contexts, name, &r)) {
@@ skipping 41 matching lines @@
         }
         return object;
       }
     }
 
     // 2. Check the context proper if it has slots.
     if (context->IsFunctionContext() || context->IsBlockContext() ||
         context->IsScriptContext()) {
       // Use serialized scope information of functions and blocks to search
       // for the context index.
-      Handle<ScopeInfo> scope_info;
-      if (context->IsFunctionContext()) {
-        scope_info = Handle<ScopeInfo>(
-            context->closure()->shared()->scope_info(), isolate);
-      } else {
-        scope_info = Handle<ScopeInfo>(
-            ScopeInfo::cast(context->extension()), isolate);
-      }
+      Handle<ScopeInfo> scope_info(context->IsFunctionContext()
+          ? context->closure()->shared()->scope_info()
+          : context->scope_info());
       VariableMode mode;
       VariableLocation location;
       InitializationFlag init_flag;
       // TODO(sigurds) Figure out whether maybe_assigned_flag should
       // be used to compute binding_flags.
       MaybeAssignedFlag maybe_assigned_flag;
       int slot_index = ScopeInfo::ContextSlotIndex(
           scope_info, name, &mode, &location, &init_flag, &maybe_assigned_flag);
       DCHECK(slot_index < 0 || slot_index >= MIN_CONTEXT_SLOTS);
       if (slot_index >= 0 && location == VariableLocation::CONTEXT) {
@@ skipping 21 matching lines @@
           *attributes = READ_ONLY;
           DCHECK(mode == CONST_LEGACY || mode == CONST);
           *binding_flags = (mode == CONST_LEGACY)
               ? IMMUTABLE_IS_INITIALIZED : IMMUTABLE_IS_INITIALIZED_HARMONY;
           return context;
         }
       }
 
     } else if (context->IsCatchContext()) {
       // Catch contexts have the variable name in the extension slot.
-      if (String::Equals(name, handle(String::cast(context->extension())))) {
+      if (String::Equals(name, handle(context->catch_name()))) {
         if (FLAG_trace_contexts) {
           PrintF("=> found in catch context\n");
         }
         *index = Context::THROWN_OBJECT_INDEX;
         *attributes = NONE;
         *binding_flags = MUTABLE_IS_INITIALIZED;
         return context;
       }
     }
 
     // 3. Prepare to continue with the previous (next outermost) context.
     if (context->IsNativeContext()) {
       follow_context_chain = false;
     } else {
       context = Handle<Context>(context->previous(), isolate);
     }
   } while (follow_context_chain);
 
   if (FLAG_trace_contexts) {
     PrintF("=> no property/slot found\n");
   }
   return Handle<Object>::null();
 }
 
 
 void Context::InitializeGlobalSlots() {
   DCHECK(IsScriptContext());
   DisallowHeapAllocation no_gc;
 
-  ScopeInfo* scope_info = ScopeInfo::cast(extension());
+  ScopeInfo* scope_info = this->scope_info();
 
   int context_globals = scope_info->ContextGlobalCount();
   if (context_globals > 0) {
     PropertyCell* empty_cell = GetHeap()->empty_property_cell();
 
     int context_locals = scope_info->ContextLocalCount();
     int index = Context::MIN_CONTEXT_SLOTS + context_locals;
     for (int i = 0; i < context_globals; i++) {
       set(index++, empty_cell);
     }
@@ skipping 138 matching lines @@
   // During bootstrapping we allow all objects to pass as global
   // objects. This is necessary to fix circular dependencies.
   return isolate->heap()->gc_state() != Heap::NOT_IN_GC ||
       isolate->bootstrapper()->IsActive() ||
       object->IsGlobalObject();
 }
 #endif
 
 }  // namespace internal
 }  // namespace v8