Improve dead phi elimination....

src/hydrogen-instructions.cc

 // Copyright 2011 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 915 matching lines @@
 void HPhi::AddInput(HValue* value) {
   inputs_.Add(NULL);
   SetOperandAt(OperandCount() - 1, value);
   // Mark phis that may have 'arguments' directly or indirectly as an operand.
   if (!CheckFlag(kIsArguments) && value->CheckFlag(kIsArguments)) {
     SetFlag(kIsArguments);
   }
 }
 
 
+bool HPhi::HasRealUses() {
+  for (int i = 0; i < uses()->length(); i++) {
+    if (!uses()->at(i)->IsPhi()) return true;
+  }
+  return false;
+}
+
+
 HValue* HPhi::GetRedundantReplacement() {
   HValue* candidate = NULL;
   int count = OperandCount();
   int position = 0;
   while (position < count && candidate == NULL) {
     HValue* current = OperandAt(position++);
     if (current != this) candidate = current;
   }
   while (position < count) {
     HValue* current = OperandAt(position++);
@@ skipping 556 matching lines @@
 
 
 void HCheckPrototypeMaps::Verify() {
   HInstruction::Verify();
   ASSERT(HasNoUses());
 }
 
 #endif
 
 } }  // namespace v8::internal