Let NaN flow as double into HBranch

src/hydrogen-instructions.cc

 // 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 1258 matching lines @@
 void HReturn::PrintDataTo(StringStream* stream) {
   value()->PrintNameTo(stream);
   stream->Add(" (pop ");
   parameter_count()->PrintNameTo(stream);
   stream->Add(" values)");
 }
 
 
 Representation HBranch::observed_input_representation(int index) {
   static const ToBooleanStub::Types tagged_types(
-      ToBooleanStub::UNDEFINED |
       ToBooleanStub::NULL_TYPE |
       ToBooleanStub::SPEC_OBJECT |
       ToBooleanStub::STRING |
       ToBooleanStub::SYMBOL);
+  static const ToBooleanStub::Types number_types(
+      ToBooleanStub::HEAP_NUMBER |
+      ToBooleanStub::SMI);
   if (expected_input_types_.ContainsAnyOf(tagged_types)) {
     return Representation::Tagged();
-  } else if (expected_input_types_.Contains(ToBooleanStub::HEAP_NUMBER)) {
+  }
+  if (expected_input_types_.Contains(ToBooleanStub::UNDEFINED)) {
+    if (expected_input_types_.ContainsAnyOf(number_types)) {

[Toon Verwaest, 2013/06/18 17:01:52]

Are you sure you want to make smi+undefined double rather than tagged? Seems
like tagged would be faster; given that smis are valid tagged objects; and you
need to do a smi-check anyway.

I'd rather make undefined a special case of Contains(HEAP_NUMBER).

+      return Representation::Double();
+    }
+    return Representation::Tagged();
+  }
+  if (expected_input_types_.Contains(ToBooleanStub::HEAP_NUMBER)) {
     return Representation::Double();
-  } else if (expected_input_types_.Contains(ToBooleanStub::SMI)) {
+  }
+  if (expected_input_types_.Contains(ToBooleanStub::SMI)) {
     return Representation::Smi();
-  } else {
-    return Representation::None();
   }
+  return Representation::None();
 }
 
 
 void HCompareMap::PrintDataTo(StringStream* stream) {
   value()->PrintNameTo(stream);
   stream->Add(" (%p)", *map());
   HControlInstruction::PrintDataTo(stream);
 }
 
 
@@ skipping 2566 matching lines @@
     case kBackingStore:
       if (!name_.is_null()) stream->Add(*String::cast(*name_)->ToCString());
       stream->Add("[backing-store]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal