Move V8 to external/v8

Change-Id: If68025d67453785a651c5dfb34fad298c16676a4

1 files changed, 831 insertions, 0 deletions

diff --git a/src/rewriter.cc b/src/rewriter.cc
new file mode 100644
index 00000000..11fc071f
--- /dev/null
+++ b/src/rewriter.cc
@@ -0,0 +1,831 @@
+// Copyright 2006-2008 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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "v8.h"
+
+#include "ast.h"
+#include "func-name-inferrer.h"
+#include "scopes.h"
+#include "rewriter.h"
+
+namespace v8 {
+namespace internal {
+
+
+class AstOptimizer: public AstVisitor {
+ public:
+  explicit AstOptimizer() : has_function_literal_(false) {}
+  explicit AstOptimizer(Handle<String> enclosing_name)
+      : has_function_literal_(false) {
+    func_name_inferrer_.PushEnclosingName(enclosing_name);
+  }
+
+  void Optimize(ZoneList<Statement*>* statements);
+
+ private:
+  // Used for loop condition analysis.  Cleared before visiting a loop
+  // condition, set when a function literal is visited.
+  bool has_function_literal_;
+  // Helper object for function name inferring.
+  FuncNameInferrer func_name_inferrer_;
+
+  // Helpers
+  void OptimizeArguments(ZoneList<Expression*>* arguments);
+
+  // Node visitors.
+#define DEF_VISIT(type) \
+  virtual void Visit##type(type* node);
+  AST_NODE_LIST(DEF_VISIT)
+#undef DEF_VISIT
+
+  DISALLOW_COPY_AND_ASSIGN(AstOptimizer);
+};
+
+
+void AstOptimizer::Optimize(ZoneList<Statement*>* statements) {
+  int len = statements->length();
+  for (int i = 0; i < len; i++) {
+    Visit(statements->at(i));
+  }
+}
+
+
+void AstOptimizer::OptimizeArguments(ZoneList<Expression*>* arguments) {
+  for (int i = 0; i < arguments->length(); i++) {
+    Visit(arguments->at(i));
+  }
+}
+
+
+void AstOptimizer::VisitBlock(Block* node) {
+  Optimize(node->statements());
+}
+
+
+void AstOptimizer::VisitExpressionStatement(ExpressionStatement* node) {
+  Visit(node->expression());
+}
+
+
+void AstOptimizer::VisitIfStatement(IfStatement* node) {
+  Visit(node->condition());
+  Visit(node->then_statement());
+  if (node->HasElseStatement()) {
+    Visit(node->else_statement());
+  }
+}
+
+
+void AstOptimizer::VisitLoopStatement(LoopStatement* node) {
+  if (node->init() != NULL) {
+    Visit(node->init());
+  }
+  if (node->cond() != NULL) {
+    has_function_literal_ = false;
+    Visit(node->cond());
+    node->may_have_function_literal_ = has_function_literal_;
+  }
+  if (node->body() != NULL) {
+    Visit(node->body());
+  }
+  if (node->next() != NULL) {
+    Visit(node->next());
+  }
+}
+
+
+void AstOptimizer::VisitForInStatement(ForInStatement* node) {
+  Visit(node->each());
+  Visit(node->enumerable());
+  Visit(node->body());
+}
+
+
+void AstOptimizer::VisitTryCatch(TryCatch* node) {
+  Visit(node->try_block());
+  Visit(node->catch_var());
+  Visit(node->catch_block());
+}
+
+
+void AstOptimizer::VisitTryFinally(TryFinally* node) {
+  Visit(node->try_block());
+  Visit(node->finally_block());
+}
+
+
+void AstOptimizer::VisitSwitchStatement(SwitchStatement* node) {
+  Visit(node->tag());
+  for (int i = 0; i < node->cases()->length(); i++) {
+    CaseClause* clause = node->cases()->at(i);
+    if (!clause->is_default()) {
+      Visit(clause->label());
+    }
+    Optimize(clause->statements());
+  }
+}
+
+
+void AstOptimizer::VisitContinueStatement(ContinueStatement* node) {
+  USE(node);
+}
+
+
+void AstOptimizer::VisitBreakStatement(BreakStatement* node) {
+  USE(node);
+}
+
+
+void AstOptimizer::VisitDeclaration(Declaration* node) {
+  // Will not be reached by the current optimizations.
+  USE(node);
+}
+
+
+void AstOptimizer::VisitEmptyStatement(EmptyStatement* node) {
+  USE(node);
+}
+
+
+void AstOptimizer::VisitReturnStatement(ReturnStatement* node) {
+  Visit(node->expression());
+}
+
+
+void AstOptimizer::VisitWithEnterStatement(WithEnterStatement* node) {
+  Visit(node->expression());
+}
+
+
+void AstOptimizer::VisitWithExitStatement(WithExitStatement* node) {
+  USE(node);
+}
+
+
+void AstOptimizer::VisitDebuggerStatement(DebuggerStatement* node) {
+  USE(node);
+}
+
+
+void AstOptimizer::VisitFunctionLiteral(FunctionLiteral* node) {
+  has_function_literal_ = true;
+
+  if (node->name()->length() == 0) {
+    // Anonymous function.
+    func_name_inferrer_.AddFunction(node);
+  }
+}
+
+
+void AstOptimizer::VisitFunctionBoilerplateLiteral(
+    FunctionBoilerplateLiteral* node) {
+  USE(node);
+}
+
+
+void AstOptimizer::VisitConditional(Conditional* node) {
+  Visit(node->condition());
+  Visit(node->then_expression());
+  Visit(node->else_expression());
+}
+
+
+void AstOptimizer::VisitSlot(Slot* node) {
+  USE(node);
+}
+
+
+void AstOptimizer::VisitVariableProxy(VariableProxy* node) {
+  Variable* var = node->AsVariable();
+  if (var != NULL) {
+    if (var->type()->IsKnown()) {
+      node->type()->CopyFrom(var->type());
+    } else if (node->type()->IsLikelySmi()) {
+      var->type()->SetAsLikelySmi();
+    }
+
+    if (!var->is_this() &&
+        !Heap::result_symbol()->Equals(*var->name())) {
+      func_name_inferrer_.PushName(var->name());
+    }
+  }
+}
+
+
+void AstOptimizer::VisitLiteral(Literal* node) {
+  Handle<Object> literal = node->handle();
+  if (literal->IsSmi()) {
+    node->type()->SetAsLikelySmi();
+  } else if (literal->IsString()) {
+    Handle<String> lit_str(Handle<String>::cast(literal));
+    if (!Heap::prototype_symbol()->Equals(*lit_str)) {
+      func_name_inferrer_.PushName(lit_str);
+    }
+  }
+}
+
+
+void AstOptimizer::VisitRegExpLiteral(RegExpLiteral* node) {
+  USE(node);
+}
+
+
+void AstOptimizer::VisitArrayLiteral(ArrayLiteral* node) {
+  for (int i = 0; i < node->values()->length(); i++) {
+    Visit(node->values()->at(i));
+  }
+}
+
+void AstOptimizer::VisitObjectLiteral(ObjectLiteral* node) {
+  for (int i = 0; i < node->properties()->length(); i++) {
+    ScopedFuncNameInferrer scoped_fni(&func_name_inferrer_);
+    scoped_fni.Enter();
+    Visit(node->properties()->at(i)->key());
+    Visit(node->properties()->at(i)->value());
+  }
+}
+
+
+void AstOptimizer::VisitCatchExtensionObject(CatchExtensionObject* node) {
+  Visit(node->key());
+  Visit(node->value());
+}
+
+
+void AstOptimizer::VisitAssignment(Assignment* node) {
+  ScopedFuncNameInferrer scoped_fni(&func_name_inferrer_);
+  switch (node->op()) {
+    case Token::INIT_VAR:
+    case Token::INIT_CONST:
+    case Token::ASSIGN:
+      // No type can be infered from the general assignment.
+
+      // Don't infer if it is "a = function(){...}();"-like expression.
+      if (node->value()->AsCall() == NULL) {
+        scoped_fni.Enter();
+      }
+      break;
+    case Token::ASSIGN_BIT_OR:
+    case Token::ASSIGN_BIT_XOR:
+    case Token::ASSIGN_BIT_AND:
+    case Token::ASSIGN_SHL:
+    case Token::ASSIGN_SAR:
+    case Token::ASSIGN_SHR:
+      node->type()->SetAsLikelySmiIfUnknown();
+      node->target()->type()->SetAsLikelySmiIfUnknown();
+      node->value()->type()->SetAsLikelySmiIfUnknown();
+      break;
+    case Token::ASSIGN_ADD:
+    case Token::ASSIGN_SUB:
+    case Token::ASSIGN_MUL:
+    case Token::ASSIGN_DIV:
+    case Token::ASSIGN_MOD:
+      if (node->type()->IsLikelySmi()) {
+        node->target()->type()->SetAsLikelySmiIfUnknown();
+        node->value()->type()->SetAsLikelySmiIfUnknown();
+      }
+      break;
+    default:
+      UNREACHABLE();
+      break;
+  }
+
+  Visit(node->target());
+  Visit(node->value());
+
+  switch (node->op()) {
+    case Token::INIT_VAR:
+    case Token::INIT_CONST:
+    case Token::ASSIGN:
+      // Pure assignment copies the type from the value.
+      node->type()->CopyFrom(node->value()->type());
+      break;
+    case Token::ASSIGN_BIT_OR:
+    case Token::ASSIGN_BIT_XOR:
+    case Token::ASSIGN_BIT_AND:
+    case Token::ASSIGN_SHL:
+    case Token::ASSIGN_SAR:
+    case Token::ASSIGN_SHR:
+      // Should have been setup above already.
+      break;
+    case Token::ASSIGN_ADD:
+    case Token::ASSIGN_SUB:
+    case Token::ASSIGN_MUL:
+    case Token::ASSIGN_DIV:
+    case Token::ASSIGN_MOD:
+      if (node->type()->IsUnknown()) {
+        if (node->target()->type()->IsLikelySmi() ||
+            node->value()->type()->IsLikelySmi()) {
+          node->type()->SetAsLikelySmi();
+        }
+      }
+      break;
+    default:
+      UNREACHABLE();
+      break;
+  }
+
+  // Since this is an assignment. We have to propagate this node's type to the
+  // variable.
+  VariableProxy* proxy = node->target()->AsVariableProxy();
+  if (proxy != NULL) {
+    Variable* var = proxy->AsVariable();
+    if (var != NULL) {
+      SmiAnalysis* var_type = var->type();
+      if (var_type->IsUnknown()) {
+        var_type->CopyFrom(node->type());
+      } else if (var_type->IsLikelySmi()) {
+        // We do not reset likely types to Unknown.
+      }
+    }
+  }
+}
+
+
+void AstOptimizer::VisitThrow(Throw* node) {
+  Visit(node->exception());
+}
+
+
+void AstOptimizer::VisitProperty(Property* node) {
+  Visit(node->obj());
+  Visit(node->key());
+}
+
+
+void AstOptimizer::VisitCall(Call* node) {
+  Visit(node->expression());
+  OptimizeArguments(node->arguments());
+}
+
+
+void AstOptimizer::VisitCallNew(CallNew* node) {
+  Visit(node->expression());
+  OptimizeArguments(node->arguments());
+}
+
+
+void AstOptimizer::VisitCallRuntime(CallRuntime* node) {
+  ScopedFuncNameInferrer scoped_fni(&func_name_inferrer_);
+  if (Factory::InitializeVarGlobal_symbol()->Equals(*node->name()) &&
+      node->arguments()->length() >= 2 &&
+      node->arguments()->at(1)->AsFunctionLiteral() != NULL) {
+      scoped_fni.Enter();
+  }
+  OptimizeArguments(node->arguments());
+}
+
+
+void AstOptimizer::VisitUnaryOperation(UnaryOperation* node) {
+  Visit(node->expression());
+}
+
+
+void AstOptimizer::VisitCountOperation(CountOperation* node) {
+  // Count operations assume that they work on Smis.
+  node->type()->SetAsLikelySmiIfUnknown();
+  node->expression()->type()->SetAsLikelySmiIfUnknown();
+  Visit(node->expression());
+}
+
+
+void AstOptimizer::VisitBinaryOperation(BinaryOperation* node) {
+  // Depending on the operation we can propagate this node's type down the
+  // AST nodes.
+  switch (node->op()) {
+    case Token::COMMA:
+    case Token::OR:
+    case Token::AND:
+      break;
+    case Token::BIT_OR:
+    case Token::BIT_XOR:
+    case Token::BIT_AND:
+    case Token::SHL:
+    case Token::SAR:
+    case Token::SHR:
+      node->type()->SetAsLikelySmiIfUnknown();
+      node->left()->type()->SetAsLikelySmiIfUnknown();
+      node->right()->type()->SetAsLikelySmiIfUnknown();
+      break;
+    case Token::ADD:
+    case Token::SUB:
+    case Token::MUL:
+    case Token::DIV:
+    case Token::MOD:
+      if (node->type()->IsLikelySmi()) {
+        node->left()->type()->SetAsLikelySmiIfUnknown();
+        node->right()->type()->SetAsLikelySmiIfUnknown();
+      }
+      break;
+    default:
+      UNREACHABLE();
+      break;
+  }
+
+  Visit(node->left());
+  Visit(node->right());
+
+  // After visiting the operand nodes we have to check if this node's type
+  // can be updated. If it does, then we can push that information down
+  // towards the leafs again if the new information is an upgrade over the
+  // previous type of the operand nodes.
+  if (node->type()->IsUnknown()) {
+    if (node->left()->type()->IsLikelySmi() ||
+        node->right()->type()->IsLikelySmi()) {
+      node->type()->SetAsLikelySmi();
+    }
+    if (node->type()->IsLikelySmi()) {
+      // The type of this node changed to LIKELY_SMI. Propagate this knowledge
+      // down through the nodes.
+      if (node->left()->type()->IsUnknown()) {
+        node->left()->type()->SetAsLikelySmi();
+        Visit(node->left());
+      }
+      if (node->right()->type()->IsUnknown()) {
+        node->right()->type()->SetAsLikelySmi();
+        Visit(node->right());
+      }
+    }
+  }
+}
+
+
+void AstOptimizer::VisitCompareOperation(CompareOperation* node) {
+  if (node->type()->IsKnown()) {
+    // Propagate useful information down towards the leafs.
+    node->left()->type()->SetAsLikelySmiIfUnknown();
+    node->right()->type()->SetAsLikelySmiIfUnknown();
+  }
+
+  Visit(node->left());
+  Visit(node->right());
+
+  // After visiting the operand nodes we have to check if this node's type
+  // can be updated. If it does, then we can push that information down
+  // towards the leafs again if the new information is an upgrade over the
+  // previous type of the operand nodes.
+  if (node->type()->IsUnknown()) {
+    if (node->left()->type()->IsLikelySmi() ||
+        node->right()->type()->IsLikelySmi()) {
+      node->type()->SetAsLikelySmi();
+    }
+    if (node->type()->IsLikelySmi()) {
+      // The type of this node changed to LIKELY_SMI. Propagate this knowledge
+      // down through the nodes.
+      if (node->left()->type()->IsUnknown()) {
+        node->left()->type()->SetAsLikelySmi();
+        Visit(node->left());
+      }
+      if (node->right()->type()->IsUnknown()) {
+        node->right()->type()->SetAsLikelySmi();
+        Visit(node->right());
+      }
+    }
+  }
+}
+
+
+void AstOptimizer::VisitThisFunction(ThisFunction* node) {
+  USE(node);
+}
+
+
+class Processor: public AstVisitor {
+ public:
+  explicit Processor(VariableProxy* result)
+      : result_(result),
+        result_assigned_(false),
+        is_set_(false),
+        in_try_(false) {
+  }
+
+  void Process(ZoneList<Statement*>* statements);
+  bool result_assigned() const  { return result_assigned_; }
+
+ private:
+  VariableProxy* result_;
+
+  // We are not tracking result usage via the result_'s use
+  // counts (we leave the accurate computation to the
+  // usage analyzer). Instead we simple remember if
+  // there was ever an assignment to result_.
+  bool result_assigned_;
+
+  // To avoid storing to .result all the time, we eliminate some of
+  // the stores by keeping track of whether or not we're sure .result
+  // will be overwritten anyway. This is a bit more tricky than what I
+  // was hoping for
+  bool is_set_;
+  bool in_try_;
+
+  Expression* SetResult(Expression* value) {
+    result_assigned_ = true;
+    return new Assignment(Token::ASSIGN, result_, value,
+                          RelocInfo::kNoPosition);
+  }
+
+  // Node visitors.
+#define DEF_VISIT(type) \
+  virtual void Visit##type(type* node);
+  AST_NODE_LIST(DEF_VISIT)
+#undef DEF_VISIT
+};
+
+
+void Processor::Process(ZoneList<Statement*>* statements) {
+  for (int i = statements->length() - 1; i >= 0; --i) {
+    Visit(statements->at(i));
+  }
+}
+
+
+void Processor::VisitBlock(Block* node) {
+  // An initializer block is the rewritten form of a variable declaration
+  // with initialization expressions. The initializer block contains the
+  // list of assignments corresponding to the initialization expressions.
+  // While unclear from the spec (ECMA-262, 3rd., 12.2), the value of
+  // a variable declaration with initialization expression is 'undefined'
+  // with some JS VMs: For instance, using smjs, print(eval('var x = 7'))
+  // returns 'undefined'. To obtain the same behavior with v8, we need
+  // to prevent rewriting in that case.
+  if (!node->is_initializer_block()) Process(node->statements());
+}
+
+
+void Processor::VisitExpressionStatement(ExpressionStatement* node) {
+  // Rewrite : <x>; -> .result = <x>;
+  if (!is_set_) {
+    node->set_expression(SetResult(node->expression()));
+    if (!in_try_) is_set_ = true;
+  }
+}
+
+
+void Processor::VisitIfStatement(IfStatement* node) {
+  // Rewrite both then and else parts (reversed).
+  bool save = is_set_;
+  Visit(node->else_statement());
+  bool set_after_then = is_set_;
+  is_set_ = save;
+  Visit(node->then_statement());
+  is_set_ = is_set_ && set_after_then;
+}
+
+
+
+
+void Processor::VisitLoopStatement(LoopStatement* node) {
+  // Rewrite loop body statement.
+  bool set_after_loop = is_set_;
+  Visit(node->body());
+  is_set_ = is_set_ && set_after_loop;
+}
+
+
+void Processor::VisitForInStatement(ForInStatement* node) {
+  // Rewrite for-in body statement.
+  bool set_after_for = is_set_;
+  Visit(node->body());
+  is_set_ = is_set_ && set_after_for;
+}
+
+
+void Processor::VisitTryCatch(TryCatch* node) {
+  // Rewrite both try and catch blocks (reversed order).
+  bool set_after_catch = is_set_;
+  Visit(node->catch_block());
+  is_set_ = is_set_ && set_after_catch;
+  bool save = in_try_;
+  in_try_ = true;
+  Visit(node->try_block());
+  in_try_ = save;
+}
+
+
+void Processor::VisitTryFinally(TryFinally* node) {
+  // Rewrite both try and finally block (reversed order).
+  Visit(node->finally_block());
+  bool save = in_try_;
+  in_try_ = true;
+  Visit(node->try_block());
+  in_try_ = save;
+}
+
+
+void Processor::VisitSwitchStatement(SwitchStatement* node) {
+  // Rewrite statements in all case clauses in reversed order.
+  ZoneList<CaseClause*>* clauses = node->cases();
+  bool set_after_switch = is_set_;
+  for (int i = clauses->length() - 1; i >= 0; --i) {
+    CaseClause* clause = clauses->at(i);
+    Process(clause->statements());
+  }
+  is_set_ = is_set_ && set_after_switch;
+}
+
+
+void Processor::VisitContinueStatement(ContinueStatement* node) {
+  is_set_ = false;
+}
+
+
+void Processor::VisitBreakStatement(BreakStatement* node) {
+  is_set_ = false;
+}
+
+
+// Do nothing:
+void Processor::VisitDeclaration(Declaration* node) {}
+void Processor::VisitEmptyStatement(EmptyStatement* node) {}
+void Processor::VisitReturnStatement(ReturnStatement* node) {}
+void Processor::VisitWithEnterStatement(WithEnterStatement* node) {}
+void Processor::VisitWithExitStatement(WithExitStatement* node) {}
+void Processor::VisitDebuggerStatement(DebuggerStatement* node) {}
+
+
+// Expressions are never visited yet.
+void Processor::VisitFunctionLiteral(FunctionLiteral* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitFunctionBoilerplateLiteral(
+    FunctionBoilerplateLiteral* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitConditional(Conditional* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitSlot(Slot* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitVariableProxy(VariableProxy* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitLiteral(Literal* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitRegExpLiteral(RegExpLiteral* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitArrayLiteral(ArrayLiteral* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitObjectLiteral(ObjectLiteral* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitCatchExtensionObject(CatchExtensionObject* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitAssignment(Assignment* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitThrow(Throw* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitProperty(Property* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitCall(Call* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitCallNew(CallNew* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitCallRuntime(CallRuntime* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitUnaryOperation(UnaryOperation* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitCountOperation(CountOperation* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitBinaryOperation(BinaryOperation* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitCompareOperation(CompareOperation* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+void Processor::VisitThisFunction(ThisFunction* node) {
+  USE(node);
+  UNREACHABLE();
+}
+
+
+bool Rewriter::Process(FunctionLiteral* function) {
+  HistogramTimerScope timer(&Counters::rewriting);
+  Scope* scope = function->scope();
+  if (scope->is_function_scope()) return true;
+
+  ZoneList<Statement*>* body = function->body();
+  if (body->is_empty()) return true;
+
+  VariableProxy* result = scope->NewTemporary(Factory::result_symbol());
+  Processor processor(result);
+  processor.Process(body);
+  if (processor.HasStackOverflow()) return false;
+
+  if (processor.result_assigned()) body->Add(new ReturnStatement(result));
+  return true;
+}
+
+
+bool Rewriter::Optimize(FunctionLiteral* function) {
+  ZoneList<Statement*>* body = function->body();
+
+  if (FLAG_optimize_ast && !body->is_empty()) {
+    HistogramTimerScope timer(&Counters::ast_optimization);
+    AstOptimizer optimizer(function->name());
+    optimizer.Optimize(body);
+    if (optimizer.HasStackOverflow()) {
+      return false;
+    }
+  }
+  return true;
+}
+
+
+} }  // namespace v8::internal