Support Smi in CompareIDAndBranch

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index bd33f1a2b7ee38eb0998d783445066d902abe59c..6a1cad27f15c2dcb3c6c6a7b419f00501efafe60 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -2460,10 +2460,16 @@ void HCompareIDAndBranch::InferRepresentation(HInferRepresentation* h_infer) {
   bool observed_integers =
       observed_input_representation(0).IsInteger32() &&
       observed_input_representation(1).IsInteger32();
-  bool inputs_are_not_doubles =
-      !left_rep.IsDouble() && !right_rep.IsDouble();
+  bool inputs_are_not_doubles = !left_rep.IsDouble() && !right_rep.IsDouble();
+
   if (observed_integers && inputs_are_not_doubles) {
-    rep = Representation::Integer32();
+    rep = Representation::Smi();
+    if (left_rep.is_more_general_than(rep) && !left_rep.IsTagged()) {
+      rep = Representation::Integer32();
+    }
+    if (right_rep.is_more_general_than(rep) && !right_rep.IsTagged()) {
+      rep = Representation::Integer32();
+    }
   } else {
     rep = Representation::Double();
     // According to the ES5 spec (11.9.3, 11.8.5), Equality comparisons (==, ===