Stack-allocate block variables

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/machine-operator.h"
@@ skipping 444 matching lines @@
 
 
 void AstGraphBuilder::VisitBlock(Block* stmt) {
   BlockBuilder block(this);
   BreakableScope scope(this, stmt, &block, 0);
   if (stmt->labels() != NULL) block.BeginBlock();
   if (stmt->scope() == NULL) {
     // Visit statements in the same scope, no declarations.
     VisitStatements(stmt->statements());
   } else {
-    const Operator* op = javascript()->CreateBlockContext();
-    Node* scope_info = jsgraph()->Constant(stmt->scope()->GetScopeInfo());
-    Node* context = NewNode(op, scope_info, GetFunctionClosure());
+    Node* context = nullptr;
+    if (stmt->scope()->ContextLocalCount() > 0) {
+      const Operator* op = javascript()->CreateBlockContext();
+      Node* scope_info = jsgraph()->Constant(stmt->scope()->GetScopeInfo());
+      context = NewNode(op, scope_info, GetFunctionClosure());
+    }
     ContextScope scope(this, stmt->scope(), context);
 
     // Visit declarations and statements in a block scope.
     VisitDeclarations(stmt->scope()->declarations());
     VisitStatements(stmt->statements());
   }
   if (stmt->labels() != NULL) block.EndBlock();
 }
 
 
@@ skipping 1744 matching lines @@
 
 BitVector* AstGraphBuilder::GetVariablesAssignedInLoop(
     IterationStatement* stmt) {
   if (loop_assignment_analysis_ == NULL) return NULL;
   return loop_assignment_analysis_->GetVariablesAssignedInLoop(stmt);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8