Small simplification of HChange instruction.

Use existing flag to mark HChange instructions that deoptimize on undefined.

Also there is no need to store the source representation explicitly.
Review URL: http://codereview.chromium.org/8066007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9472 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.cc

@@ -796,10 +796,11 @@ void HTypeof::PrintDataTo(StringStream* stream) {
 
 void HChange::PrintDataTo(StringStream* stream) {
   HUnaryOperation::PrintDataTo(stream);
-  stream->Add(" %s to %s", from_.Mnemonic(), to().Mnemonic());
+  stream->Add(" %s to %s", from().Mnemonic(), to().Mnemonic());
 
   if (CanTruncateToInt32()) stream->Add(" truncating-int32");
   if (CheckFlag(kBailoutOnMinusZero)) stream->Add(" -0?");
+  if (CheckFlag(kDeoptimizeOnUndefined)) stream->Add(" deopt-on-undefined");
 }
 
 

src/hydrogen.cc

@@ -1860,7 +1860,7 @@ void HGraph::InsertRepresentationChangeForUse(HValue* value,
   }
 
   if (new_value == NULL) {
-    new_value = new(zone()) HChange(value, value->representation(), to,
+    new_value = new(zone()) HChange(value, to,
                                     is_truncating, deoptimize_on_undefined);
   }