Check that environments assigned via AssignEnvironment are actually used.

src/lithium.h

 // Copyright 2012 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
@@ skipping 408 matching lines @@
         ast_id_(ast_id),
         translation_size_(value_count),
         parameter_count_(parameter_count),
         pc_offset_(-1),
         values_(value_count, zone),
         is_tagged_(value_count, zone),
         is_uint32_(value_count, zone),
         object_mapping_(0, zone),
         outer_(outer),
         entry_(entry),
-        zone_(zone) { }
+        zone_(zone),
+        has_been_used_(false) { }
 
   Handle<JSFunction> closure() const { return closure_; }
   FrameType frame_type() const { return frame_type_; }
   int arguments_stack_height() const { return arguments_stack_height_; }
   int deoptimization_index() const { return deoptimization_index_; }
   int translation_index() const { return translation_index_; }
   BailoutId ast_id() const { return ast_id_; }
   int translation_size() const { return translation_size_; }
   int parameter_count() const { return parameter_count_; }
   int pc_offset() const { return pc_offset_; }
   const ZoneList<LOperand*>* values() const { return &values_; }
   LEnvironment* outer() const { return outer_; }
   HEnterInlined* entry() { return entry_; }
   Zone* zone() const { return zone_; }
 
+  bool has_been_used() const { return has_been_used_; }
+  void set_has_been_used() { has_been_used_ = true; }
+
   void AddValue(LOperand* operand,
                 Representation representation,
                 bool is_uint32) {
     values_.Add(operand, zone());
     if (representation.IsSmiOrTagged()) {
       ASSERT(!is_uint32);
       is_tagged_.Add(values_.length() - 1, zone());
     }
 
     if (is_uint32) {
@@ skipping 79 matching lines @@
   ZoneList<LOperand*> values_;
   GrowableBitVector is_tagged_;
   GrowableBitVector is_uint32_;
 
   // Map with encoded information about materialization_marker operands.
   ZoneList<uint32_t> object_mapping_;
 
   LEnvironment* outer_;
   HEnterInlined* entry_;
   Zone* zone_;
+  bool has_been_used_;
 };
 
 
 // Iterates over the non-null, non-constant operands in an environment.
 class ShallowIterator V8_FINAL BASE_EMBEDDED {
  public:
   explicit ShallowIterator(LEnvironment* env)
       : env_(env),
         limit_(env != NULL ? env->values()->length() : 0),
         current_(0) {
@@ skipping 177 matching lines @@
  private:
   LChunk* chunk_;
 
   DISALLOW_COPY_AND_ASSIGN(LPhase);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_LITHIUM_H_