[turbofan] Initial version of number type feedback.

src/compiler/type-hints.h

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COMPILER_TYPE_HINTS_H_
 #define V8_COMPILER_TYPE_HINTS_H_
 
 #include "src/base/flags.h"
 #include "src/utils.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 // Type hints for an binary operation.
 class BinaryOperationHints final {
  public:
-  enum Hint { kNone, kSignedSmall, kSigned32, kNumber, kString, kAny };
+  enum Hint {
+    kNone,
+    kSignedSmall,
+    kSigned32,
+    kNumberOrUndefined,
+    kString,
+    kAny
+  };
 
   BinaryOperationHints() : BinaryOperationHints(kNone, kNone, kNone) {}
   BinaryOperationHints(Hint left, Hint right, Hint result)
       : bit_field_(LeftField::encode(left) | RightField::encode(right) |
                    ResultField::encode(result)) {}
 
   static BinaryOperationHints Any() {
     return BinaryOperationHints(kAny, kAny, kAny);
   }
 
   Hint left() const { return LeftField::decode(bit_field_); }
   Hint right() const { return RightField::decode(bit_field_); }
   Hint result() const { return ResultField::decode(bit_field_); }
+  Hint combined() const { return Combine(Combine(left(), right()), result()); }
+
+  // Hint 'subtyping' and generalization.
+  static bool Is(Hint h1, Hint h2);
+  static Hint Combine(Hint h1, Hint h2);
 
   bool operator==(BinaryOperationHints const& that) const {
     return this->bit_field_ == that.bit_field_;
   }
   bool operator!=(BinaryOperationHints const& that) const {
     return !(*this == that);
   }
 
   friend size_t hash_value(BinaryOperationHints const& hints) {
     return hints.bit_field_;
@@ skipping 33 matching lines @@
 
 std::ostream& operator<<(std::ostream&, ToBooleanHints);
 
 DEFINE_OPERATORS_FOR_FLAGS(ToBooleanHints)
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_TYPE_HINTS_H_