[Interpreter] Collect feedback about Oddballs in Subtract Stub.

src/globals.h

Index: src/globals.h
diff --git a/src/globals.h b/src/globals.h
index 03c5b1dc1a964e70270713e400d8ada1a617d723..9d0a6b76bbdab80e725fbf6dc000829f4bb78d57 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -1208,15 +1208,21 @@ inline uint32_t ObjectHash(Address address) {
 // Type feedback is encoded in such a way that, we can combine the feedback
 // at different points by performing an 'OR' operation. Type feedback moves
 // to a more generic type when we combine feedback.
-// kSignedSmall -> kNumber  -> kAny
-//                 kString  -> kAny
+// kSignedSmall -> kNumber  -> kNumberOrOddball -> kAny
+//                             kString          -> kAny
+// TODO(mythria): Remove kNumber type when crankshaft can handle Oddballs
+// similar to Numbers. We don't need kNumber feedback for Turbofan. Extra
+// information about Number might reduce few instructions but causes more
+// deopts. We collect Number only because crankshaft does not handle all
+// cases of oddballs.
 class BinaryOperationFeedback {
  public:
   enum {
     kNone = 0x0,
     kSignedSmall = 0x1,
     kNumber = 0x3,
-    kString = 0x4,
+    kNumberOrOddball = 0x7,
+    kString = 0x8,
     kAny = 0xF

[Leszek Swirski, 2016/10/10 11:57:22]

Should kAny change to 0x1F, so that it has a value beyond kNumberOrOddball |
kString (i.e. so that it has a bit set for non-number, non-strings)?

[mythria, 2016/10/10 13:26:00]

Good point. Done.

   };
 };