Reduce impact of HParameter inputs on HPhi representation selection

src/hydrogen-instructions.h

 // Copyright 2012 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_HYDROGEN_INSTRUCTIONS_H_
 #define V8_HYDROGEN_INSTRUCTIONS_H_
 
 #include <iosfwd>
 
 #include "src/v8.h"
@@ skipping 1623 matching lines @@
 };
 
 
 class HForceRepresentation FINAL : public HTemplateInstruction<1> {
  public:
   static HInstruction* New(Zone* zone, HValue* context, HValue* value,
                            Representation required_representation);
 
   HValue* value() const { return OperandAt(0); }
 
+  Representation observed_input_representation(int index) OVERRIDE {
+    // We haven't actually *observed* this, but it's closer to the truth
+    // than 'None'.
+    return representation();  // Same as the output representation.
+  }
   Representation RequiredInputRepresentation(int index) OVERRIDE {
     return representation();  // Same as the output representation.
   }
 
   std::ostream& PrintDataTo(std::ostream& os) const OVERRIDE;  // NOLINT
 
   DECLARE_CONCRETE_INSTRUCTION(ForceRepresentation)
 
  private:
   HForceRepresentation(HValue* value, Representation required_representation) {
@@ skipping 6366 matching lines @@
 };
 
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_