Refactor HType to get rid of various hacks.

src/hydrogen-types.h

+// Copyright 2014 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 HYDROGEN_TYPES_H_
+#define HYDROGEN_TYPES_H_
+
+#include <climits>
+
+#include "base/macros.h"
+
+namespace v8 {
+namespace internal {
+
+// Forward declarations.
+template <typename T> class Handle;
+class Object;
+
+#define HTYPE_LIST(V)                                 \
+  V(Any, 0x0)              /* 0000 0000 0000 0000 */  \
+  V(Tagged, 0x1)           /* 0000 0000 0000 0001 */  \
+  V(TaggedPrimitive, 0x5)  /* 0000 0000 0000 0101 */  \
+  V(TaggedNumber, 0xd)     /* 0000 0000 0000 1101 */  \
+  V(Smi, 0x1d)             /* 0000 0000 0001 1101 */  \
+  V(HeapObject, 0x21)      /* 0000 0000 0010 0001 */  \
+  V(HeapPrimitive, 0x25)   /* 0000 0000 0010 0101 */  \
+  V(Null, 0x27)            /* 0000 0000 0010 0111 */  \
+  V(HeapNumber, 0x2d)      /* 0000 0000 0010 1101 */  \
+  V(String, 0x65)          /* 0000 0000 0110 0101 */  \
+  V(Boolean, 0xa5)         /* 0000 0000 1010 0101 */  \
+  V(Undefined, 0x125)      /* 0000 0001 0010 0101 */  \
+  V(JSObject, 0x221)       /* 0000 0010 0010 0001 */  \
+  V(JSArray, 0x621)        /* 0000 0110 0010 0001 */  \
+  V(None, 0x7ff)           /* 0000 0111 1111 1111 */
+
+class HType V8_FINAL {
+ public:
+  #define DECLARE_CONSTRUCTOR(Name, mask) \
+    static HType Name() V8_WARN_UNUSED_RESULT { return HType(k##Name); }
+  HTYPE_LIST(DECLARE_CONSTRUCTOR)
+  #undef DECLARE_CONSTRUCTOR
+
+  // Return the weakest (least precise) common type.
+  HType Combine(HType other) const V8_WARN_UNUSED_RESULT {
+    return HType(static_cast<Kind>(kind_ & other.kind_));
+  }
+
+  bool Equals(HType other) const V8_WARN_UNUSED_RESULT {
+    return kind_ == other.kind_;
+  }
+
+  bool IsSubtypeOf(HType other) const V8_WARN_UNUSED_RESULT {
+    return Combine(other).Equals(other);
+  }
+
+  #define DECLARE_IS_TYPE(Name, mask)               \
+    bool Is##Name() const V8_WARN_UNUSED_RESULT {   \
+      return IsSubtypeOf(HType::Name());            \
+    }
+  HTYPE_LIST(DECLARE_IS_TYPE)
+  #undef DECLARE_IS_TYPE
+
+  template <class T>
+  static HType FromType(typename T::TypeHandle type) V8_WARN_UNUSED_RESULT;
+  static HType FromValue(Handle<Object> value) V8_WARN_UNUSED_RESULT;
+
+  const char* ToString() const V8_WARN_UNUSED_RESULT;
+
+ private:
+  enum Kind {
+    #define DECLARE_TYPE(Name, mask) k##Name = mask,
+    HTYPE_LIST(DECLARE_TYPE)
+    #undef DECLARE_TYPE
+    LAST_KIND = kNone
+  };
+
+  // Make sure type fits in int16.
+  STATIC_ASSERT(LAST_KIND < (1 << (CHAR_BIT * sizeof(int16_t))));
+
+  explicit HType(Kind kind) : kind_(kind) { }
+
+  int16_t kind_;
+};
+
+} }  // namespace v8::internal
+
+#endif  // HYDROGEN_TYPES_H_