[turbofan] Fix context chain extension for top-level code.

src/compiler/ast-graph-builder.cc

 // Copyright 2014 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/compiler/ast-graph-builder.h"
 
 #include "src/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/js-type-feedback.h"
@@ skipping 435 matching lines @@
       exit_controls_(local_zone),
       loop_assignment_analysis_(loop),
       state_values_cache_(jsgraph),
       liveness_analyzer_(static_cast<size_t>(info->scope()->num_stack_slots()),
                          local_zone),
       js_type_feedback_(js_type_feedback) {
   InitializeAstVisitor(info->isolate(), local_zone);
 }
 
 
+Node* AstGraphBuilder::GetFunctionClosureForContext() {
+  Scope* declaration_scope = current_scope()->DeclarationScope();
+  if (declaration_scope->is_script_scope() ||
+      declaration_scope->is_module_scope()) {
+    // Contexts nested in the native context have a canonical empty function as
+    // their closure, not the anonymous closure containing the global code.
+    // Pass a SMI sentinel and let the runtime look up the empty function.
+    return jsgraph()->SmiConstant(0);
+  } else {
+    DCHECK(declaration_scope->is_function_scope());
+    return GetFunctionClosure();
+  }
+}
+
+
 Node* AstGraphBuilder::GetFunctionClosure() {
   if (!function_closure_.is_set()) {
     const Operator* op = common()->Parameter(
         Linkage::kJSFunctionCallClosureParamIndex, "%closure");
     Node* node = NewNode(op, graph()->start());
     function_closure_.set(node);
   }
   return function_closure_.get();
 }
 
@@ skipping 708 matching lines @@
   VisitForValue(stmt->expression());
   Node* result = environment()->Pop();
   execution_control()->ReturnValue(result);
 }
 
 
 void AstGraphBuilder::VisitWithStatement(WithStatement* stmt) {
   VisitForValue(stmt->expression());
   Node* value = environment()->Pop();
   const Operator* op = javascript()->CreateWithContext();
-  Node* context = NewNode(op, value, GetFunctionClosure());
+  Node* context = NewNode(op, value, GetFunctionClosureForContext());
   PrepareFrameState(context, stmt->EntryId());
   ContextScope scope(this, stmt->scope(), context);
   Visit(stmt->statement());
 }
 
 
 void AstGraphBuilder::VisitSwitchStatement(SwitchStatement* stmt) {
   ZoneList<CaseClause*>* clauses = stmt->cases();
   SwitchBuilder compare_switch(this, clauses->length());
   ControlScopeForBreakable scope(this, stmt, &compare_switch);
@@ skipping 197 matching lines @@
   // Clear message object as we enter the catch block.
   ExternalReference message_object =
       ExternalReference::address_of_pending_message_obj(isolate());
   Node* the_hole = jsgraph()->TheHoleConstant();
   BuildStoreExternal(message_object, kMachAnyTagged, the_hole);
 
   // Create a catch scope that binds the exception.
   Node* exception = try_control.GetExceptionNode();
   Unique<String> name = MakeUnique(stmt->variable()->name());
   const Operator* op = javascript()->CreateCatchContext(name);
-  Node* context = NewNode(op, exception, GetFunctionClosure());
+  Node* context = NewNode(op, exception, GetFunctionClosureForContext());
   PrepareFrameState(context, BailoutId::None());
   {
     ContextScope scope(this, stmt->scope(), context);
     DCHECK(stmt->scope()->declarations()->is_empty());
     // Evaluate the catch-block.
     Visit(stmt->catch_block());
   }
   try_control.EndCatch();
 
   // TODO(mstarzinger): Remove bailout once everything works.
@@ skipping 1634 matching lines @@
     DCHECK_EQ(0, scope->ContextChainLength(variable->scope()));
     const Operator* op = javascript()->StoreContext(0, variable->index());
     NewNode(op, local_context, parameter);
   }
 
   return local_context;
 }
 
 
 Node* AstGraphBuilder::BuildLocalScriptContext(Scope* scope) {
-  Node* closure = GetFunctionClosure();
+  DCHECK(scope->is_script_scope());
 
   // Allocate a new local context.
   const Operator* op = javascript()->CreateScriptContext();
   Node* scope_info = jsgraph()->Constant(scope->GetScopeInfo(isolate()));
-  Node* local_context = NewNode(op, closure, scope_info);
+  Node* local_context = NewNode(op, GetFunctionClosure(), scope_info);
   PrepareFrameState(local_context, BailoutId::FunctionEntry());
 
   return local_context;
 }
 
 
 Node* AstGraphBuilder::BuildLocalBlockContext(Scope* scope) {
-  Node* closure = GetFunctionClosure();
+  DCHECK(scope->is_block_scope());
 
   // Allocate a new local context.
   const Operator* op = javascript()->CreateBlockContext();
   Node* scope_info = jsgraph()->Constant(scope->GetScopeInfo(isolate()));
-  Node* local_context = NewNode(op, scope_info, closure);
+  Node* local_context = NewNode(op, scope_info, GetFunctionClosureForContext());
 
   return local_context;
 }
 
 
 Node* AstGraphBuilder::BuildArgumentsObject(Variable* arguments) {
   if (arguments == NULL) return NULL;
 
   // Allocate and initialize a new arguments object.
   Node* callee = GetFunctionClosure();
@@ skipping 954 matching lines @@
     // Phi does not exist yet, introduce one.
     value = NewPhi(inputs, value, control);
     value->ReplaceInput(inputs - 1, other);
   }
   return value;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8