Use constant types to represent the fixed right arg of a MOD.

src/ic.cc

Index: src/ic.cc
diff --git a/src/ic.cc b/src/ic.cc
index 8a25504564640c17e7a8f5f067889a2b6aececa8..b548bc68609675d7fa100e1c32c78fe6bdb4f93c 100644
--- a/src/ic.cc
+++ b/src/ic.cc
@@ -2329,7 +2329,10 @@ BinaryOpIC::State::State(ExtraICState extra_ic_state) {
       1 << FixedRightArgValueField::decode(extra_ic_state));
   left_kind_ = LeftKindField::decode(extra_ic_state);
   if (fixed_right_arg_.has_value) {
-    right_kind_ = Smi::IsValid(fixed_right_arg_.value) ? SMI : INT32;
+    // We have only 4 bits to encode the log2 of the fixed right arg, so the
+    // max value is 2^(2^4), which is always a SMI.
+    ASSERT(Smi::IsValid(fixed_right_arg_.value));
+    right_kind_ = SMI;
   } else {
     right_kind_ = RightKindField::decode(extra_ic_state);
   }
@@ -2582,6 +2585,17 @@ void BinaryOpIC::State::GenerateAheadOfTime(
 }
 
 
+Handle<Type> BinaryOpIC::State::GetRightType(Isolate* isolate) const {
+  if (fixed_right_arg_.has_value) {
+    Handle<Smi> value = handle(Smi::FromInt(fixed_right_arg_.value), isolate);
+    Handle<Type> type = handle(Type::Constant(value, isolate), isolate);
+    ASSERT(type->Is(KindToType(right_kind_, isolate)));
+    return type;
+  }
+  return KindToType(right_kind_, isolate);
+}
+
+
 Handle<Type> BinaryOpIC::State::GetResultType(Isolate* isolate) const {
   Kind result_kind = result_kind_;
   if (HasSideEffects()) {