Change the inlining context from an enum to a class.

runtime/vm/intermediate_language.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 1065 matching lines @@
 
   bool has_propagated_cid() const { return propagated_cid_ != kIllegalCid; }
   intptr_t propagated_cid() const { return propagated_cid_; }
 
   // May compute and set propagated cid.
   virtual intptr_t GetPropagatedCid();
 
   // Returns true if the propagated cid has changed.
   bool SetPropagatedCid(intptr_t cid);
 
-  Value* input_use_list() { return input_use_list_; }
+  bool HasUses() const {
+    return (input_use_list_ != NULL) || (env_use_list_ != NULL);
+  }
+
+  Value* input_use_list() const { return input_use_list_; }
   void set_input_use_list(Value* head) { input_use_list_ = head; }
 
-  Value* env_use_list() { return env_use_list_; }
+  Value* env_use_list() const { return env_use_list_; }
   void set_env_use_list(Value* head) { env_use_list_ = head; }
 
   // Replace uses of this definition with uses of other definition or value.
   // Precondition: use lists must be properly calculated.
   // Postcondition: use lists and use values are still valid.
   void ReplaceUsesWith(Definition* other);
 
   // Replace this definition and all uses with another definition.  If
   // replacing during iteration, pass the iterator so that the instruction
   // can be replaced without affecting iteration order, otherwise pass a
@@ skipping 3236 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_