Derive synthetic type bounds for expressions

src/typing.h

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 50 matching lines @@
 
   TypeFeedbackOracle* oracle() { return &oracle_; }
   Zone* zone() const { return info_->zone(); }
 
   void MergeLowerType(Expression* e, Handle<Type> t) {
     e->set_lower_type(handle(Type::Union(e->lower_type(), t), isolate_));
   }
   void MergeUpperType(Expression* e, Handle<Type> t) {
     e->set_upper_type(handle(Type::Intersect(e->upper_type(), t), isolate_));
   }
+  void MergeLowerType(Expression* e, Type* t) {
+    MergeLowerType(e, handle(t, isolate_));
+  }
+  void MergeUpperType(Expression* e, Type* t) {
+    MergeUpperType(e, handle(t, isolate_));
+  }
+
+  static Type* BoundedType(Type* bound, Handle<Type> type) {
+    return type->Is(bound) ? *type : bound;
+  }
+  static Type* AdditionType(Handle<Type> type) {
+    return type->Is(Type::Number()) ? Type::Number() :
+           type->Is(Type::String()) ? Type::String() : Type::NumberOrString();
+  }
 
   void VisitDeclarations(ZoneList<Declaration*>* declarations);
   void VisitStatements(ZoneList<Statement*>* statements);
 
 #define DECLARE_VISIT(type) virtual void Visit##type(type* node);
   AST_NODE_LIST(DECLARE_VISIT)
 #undef DECLARE_VISIT
 
   DISALLOW_COPY_AND_ASSIGN(AstTyper);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_TYPING_H_