Introduce type Bounds record

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 16 matching lines @@
 
 #ifndef V8_TYPING_H_
 #define V8_TYPING_H_
 
 #include "v8.h"
 
 #include "allocation.h"
 #include "ast.h"
 #include "compiler.h"
 #include "type-info.h"
+#include "types.h"
 #include "zone.h"
 #include "scopes.h"
 
 namespace v8 {
 namespace internal {
 
 
 class AstTyper: public AstVisitor {
  public:
   static void Run(CompilationInfo* info);
 
   void* operator new(size_t size, Zone* zone) {
     return zone->New(static_cast<int>(size));
   }
   void operator delete(void* pointer, Zone* zone) { }
   void operator delete(void* pointer) { }
 
   DEFINE_AST_VISITOR_SUBCLASS_MEMBERS();
 
  private:
   explicit AstTyper(CompilationInfo* info);
 
   CompilationInfo* info_;
   TypeFeedbackOracle oracle_;
 
   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 NarrowType(Expression* e, Bounds b) {
+    e->set_bounds(Bounds::Both(e->bounds(), b, 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_));
+  void NarrowLowerType(Expression* e, Handle<Type> t) {
+    e->set_bounds(Bounds::NarrowLower(e->bounds(), t, isolate_));
   }
 
   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_