Make it more explicit about the rfactor flag propagation

csrc/ir/internal_base_nodes.h

@@ -131,7 +131,25 @@ class NVF_API IterDomain : public Val {
       IterDomain* in,
       Val* factor,
       bool inner_split,
-      bool rfactor_domain = false);
+      bool rfactor_domain);
+
+  // Shortcut of the above split function. Previously, the above split function
+  // had a default value of false for the rfactor_domain flag. The
+  // default value is removed as it may implicitly drop
+  // the rfactor flag when the input is an rfactor iter domain, which
+  // may not be intended behavior. This
+  // shortcut is added to provide the backward compatible API with an
+  // assertion that the input iter domain is not indeed an rfactor domain.
+  static std::pair<IterDomain*, IterDomain*> split(
+      IterDomain* in,
+      Val* factor,
+      bool inner_split) {
+    NVF_ERROR(
+        !in->isRFactorProduct(),
+        "Unexpected input iter domain. Input should not be an rfactor iter domain: ",
+        in->toString());
+    return IterDomain::split(in, factor, inner_split, false);
+  }
 
   //! Resize an IterDomain by expanding both the left and right sides
   //! by given widths. The resulting IterDomain has an extent of