Implement loop variable assignment analysis.

src/compiler/graph-builder.h

 // 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.
 
 #ifndef V8_COMPILER_GRAPH_BUILDER_H_
 #define V8_COMPILER_GRAPH_BUILDER_H_
 
 #include "src/v8.h"
 
 #include "src/allocation.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph.h"
 #include "src/unique.h"
 
 namespace v8 {
 namespace internal {
+
+class BitVector;
+
 namespace compiler {
 
 class Node;
 
 // A common base class for anything that creates nodes in a graph.
 class GraphBuilder {
  public:
   explicit GraphBuilder(Graph* graph) : graph_(graph) {}
   virtual ~GraphBuilder() {}
 
@@ skipping 169 matching lines @@
   Environment* CopyForConditional() { return builder()->CopyEnvironment(this); }
 
   // Copies this environment to a potentially unreachable control-flow point.
   Environment* CopyAsUnreachable() {
     Environment* env = builder()->CopyEnvironment(this);
     env->MarkAsUnreachable();
     return env;
   }
 
   // Copies this environment at a loop header control-flow point.
-  Environment* CopyForLoop() {
-    PrepareForLoop();
+  Environment* CopyForLoop(BitVector* assigned) {
+    PrepareForLoop(assigned);
     return builder()->CopyEnvironment(this);
   }
 
   Node* GetContext() { return builder_->current_context(); }
 
  protected:
   Zone* zone() const { return builder_->local_zone(); }
   Graph* graph() const { return builder_->graph(); }
   StructuredGraphBuilder* builder() const { return builder_; }
   CommonOperatorBuilder* common() { return builder_->common(); }
   NodeVector* values() { return &values_; }
 
   // Prepare environment to be used as loop header.
-  void PrepareForLoop();
+  void PrepareForLoop(BitVector* assigned);
 
  private:
   StructuredGraphBuilder* builder_;
   Node* control_dependency_;
   Node* effect_dependency_;
   NodeVector values_;
 };
 }
 }
 }  // namespace v8::internal::compiler
 
 #endif  // V8_COMPILER_GRAPH_BUILDER_H__