Implement loop variable assignment analysis.

src/compiler/control-builders.cc

 // Copyright 2013 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 "control-builders.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
@@ skipping 14 matching lines @@
   builder_->NewIfFalse();
 }
 
 
 void IfBuilder::End() {
   then_environment_->Merge(environment());
   set_environment(then_environment_);
 }
 
 
-void LoopBuilder::BeginLoop() {
+void LoopBuilder::BeginLoop(BitVector* assigned) {
   builder_->NewLoop();
-  loop_environment_ = environment()->CopyForLoop();
+  loop_environment_ = environment()->CopyForLoop(assigned);
   continue_environment_ = environment()->CopyAsUnreachable();
   break_environment_ = environment()->CopyAsUnreachable();
 }
 
 
 void LoopBuilder::Continue() {
   continue_environment_->Merge(environment());
   environment()->MarkAsUnreachable();
 }
 
@@ skipping 87 matching lines @@
 }
 
 
 void BlockBuilder::EndBlock() {
   break_environment_->Merge(environment());
   set_environment(break_environment_);
 }
 }
 }
 }  // namespace v8::internal::compiler