Let NaN flow as double into HBranch

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 8a6ccbc9e2cbe364fb7e973372e478437c45a73d..7075e80faa1740676c07d84c3cefa908286e0fca 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -1276,20 +1276,29 @@ void HReturn::PrintDataTo(StringStream* stream) {
 
 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();
 }