Use unsigned type bitsets to limit undefined behaviour

R=bmeurer@chromium.org, svenpanne@chromium.org
BUG=

Review URL: https://codereview.chromium.org/555153003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23916 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/types-inl.h

@@ -70,7 +70,7 @@ T* ZoneTypeConfig::cast(Type* type) {
 
 // static
 bool ZoneTypeConfig::is_bitset(Type* type) {
-  return reinterpret_cast<intptr_t>(type) & 1;
+  return reinterpret_cast<uintptr_t>(type) & 1;
 }
 
 
@@ -87,9 +87,9 @@ bool ZoneTypeConfig::is_class(Type* type) {
 
 
 // static
-int ZoneTypeConfig::as_bitset(Type* type) {
+ZoneTypeConfig::Type::bitset ZoneTypeConfig::as_bitset(Type* type) {
   DCHECK(is_bitset(type));
-  return static_cast<int>(reinterpret_cast<intptr_t>(type) >> 1);
+  return reinterpret_cast<Type::bitset>(type) ^ 1u;
 }
 
 
@@ -108,13 +108,14 @@ i::Handle<i::Map> ZoneTypeConfig::as_class(Type* type) {
 
 
 // static
-ZoneTypeConfig::Type* ZoneTypeConfig::from_bitset(int bitset) {
-  return reinterpret_cast<Type*>((bitset << 1) | 1);
+ZoneTypeConfig::Type* ZoneTypeConfig::from_bitset(Type::bitset bitset) {
+  return reinterpret_cast<Type*>(bitset | 1u);
 }
 
 
 // static
-ZoneTypeConfig::Type* ZoneTypeConfig::from_bitset(int bitset, Zone* Zone) {
+ZoneTypeConfig::Type* ZoneTypeConfig::from_bitset(
+    Type::bitset bitset, Zone* Zone) {
   return from_bitset(bitset);
 }
 
@@ -229,8 +230,9 @@ bool HeapTypeConfig::is_struct(Type* type, int tag) {
 
 
 // static
-int HeapTypeConfig::as_bitset(Type* type) {
-  return i::Smi::cast(type)->value();
+HeapTypeConfig::Type::bitset HeapTypeConfig::as_bitset(Type* type) {
+  // TODO(rossberg): Breaks the Smi abstraction. Fix once there is a better way.
+  return reinterpret_cast<Type::bitset>(type);
 }
 
 
@@ -247,14 +249,15 @@ i::Handle<HeapTypeConfig::Struct> HeapTypeConfig::as_struct(Type* type) {
 
 
 // static
-HeapTypeConfig::Type* HeapTypeConfig::from_bitset(int bitset) {
-  return Type::cast(i::Smi::FromInt(bitset));
+HeapTypeConfig::Type* HeapTypeConfig::from_bitset(Type::bitset bitset) {
+  // TODO(rossberg): Breaks the Smi abstraction. Fix once there is a better way.
+  return reinterpret_cast<Type*>(bitset);
 }
 
 
 // static
 i::Handle<HeapTypeConfig::Type> HeapTypeConfig::from_bitset(
-    int bitset, Isolate* isolate) {
+    Type::bitset bitset, Isolate* isolate) {
   return i::handle(from_bitset(bitset), isolate);
 }
 

src/types.cc

@@ -30,7 +30,8 @@ static bool deq(double x, double y) {
 
 // The largest bitset subsumed by this type.
 template<class Config>
-int TypeImpl<Config>::BitsetType::Glb(TypeImpl* type) {
+typename TypeImpl<Config>::bitset
+TypeImpl<Config>::BitsetType::Glb(TypeImpl* type) {
   DisallowHeapAllocation no_allocation;
   if (type->IsBitset()) {
     return type->AsBitset();
@@ -46,17 +47,18 @@ int TypeImpl<Config>::BitsetType::Glb(TypeImpl* type) {
 
 // The smallest bitset subsuming this type.
 template<class Config>
-int TypeImpl<Config>::BitsetType::Lub(TypeImpl* type) {
+typename TypeImpl<Config>::bitset
+TypeImpl<Config>::BitsetType::Lub(TypeImpl* type) {
   DisallowHeapAllocation no_allocation;
   if (type->IsBitset()) {
     return type->AsBitset();
   } else if (type->IsUnion()) {
     UnionHandle unioned = handle(type->AsUnion());
-    int bitset = kNone;
+    bitset result = kNone;
     for (int i = 0; i < unioned->Length(); ++i) {
-      bitset |= unioned->Get(i)->BitsetLub();
+      result |= unioned->Get(i)->BitsetLub();
     }
-    return bitset;
+    return result;
   } else if (type->IsClass()) {
     // Little hack to avoid the need for a region for handlification here...
     return Config::is_class(type) ? Lub(*Config::as_class(type)) :
@@ -80,17 +82,18 @@ int TypeImpl<Config>::BitsetType::Lub(TypeImpl* type) {
 
 // The smallest bitset subsuming this type, ignoring explicit bounds.
 template<class Config>
-int TypeImpl<Config>::BitsetType::InherentLub(TypeImpl* type) {
+typename TypeImpl<Config>::bitset
+TypeImpl<Config>::BitsetType::InherentLub(TypeImpl* type) {
   DisallowHeapAllocation no_allocation;
   if (type->IsBitset()) {
     return type->AsBitset();
   } else if (type->IsUnion()) {
     UnionHandle unioned = handle(type->AsUnion());
-    int bitset = kNone;
+    bitset result = kNone;
     for (int i = 0; i < unioned->Length(); ++i) {
-      bitset |= unioned->Get(i)->InherentBitsetLub();
+      result |= unioned->Get(i)->InherentBitsetLub();
     }
-    return bitset;
+    return result;
   } else if (type->IsClass()) {
     return Lub(*type->AsClass()->Map());
   } else if (type->IsConstant()) {
@@ -111,7 +114,8 @@ int TypeImpl<Config>::BitsetType::InherentLub(TypeImpl* type) {
 
 
 template<class Config>
-int TypeImpl<Config>::BitsetType::Lub(i::Object* value) {
+typename TypeImpl<Config>::bitset
+TypeImpl<Config>::BitsetType::Lub(i::Object* value) {
   DisallowHeapAllocation no_allocation;
   if (value->IsNumber()) {
     return Lub(value->Number()) & (value->IsSmi() ? kTaggedInt : kTaggedPtr);
@@ -121,7 +125,8 @@ int TypeImpl<Config>::BitsetType::Lub(i::Object* value) {
 
 
 template<class Config>
-int TypeImpl<Config>::BitsetType::Lub(double value) {
+typename TypeImpl<Config>::bitset
+TypeImpl<Config>::BitsetType::Lub(double value) {
   DisallowHeapAllocation no_allocation;
   if (i::IsMinusZero(value)) return kMinusZero;
   if (std::isnan(value)) return kNaN;
@@ -132,19 +137,21 @@ int TypeImpl<Config>::BitsetType::Lub(double value) {
 
 
 template<class Config>
-int TypeImpl<Config>::BitsetType::Lub(double min, double max) {
+typename TypeImpl<Config>::bitset
+TypeImpl<Config>::BitsetType::Lub(double min, double max) {
   DisallowHeapAllocation no_allocation;
   DCHECK(dle(min, max));
   if (deq(min, max)) return BitsetType::Lub(min);  // Singleton range.
-  int bitset = BitsetType::kNumber ^ SEMANTIC(BitsetType::kNaN);
-  if (dle(0, min) || max < 0) bitset ^= SEMANTIC(BitsetType::kMinusZero);
-  return bitset;
+  bitset result = BitsetType::kNumber ^ SEMANTIC(BitsetType::kNaN);
+  if (dle(0, min) || max < 0) result ^= SEMANTIC(BitsetType::kMinusZero);
+  return result;
   // TODO(neis): Could refine this further by doing more checks on min/max.
 }
 
 
 template<class Config>
-int TypeImpl<Config>::BitsetType::Lub(int32_t value) {
+typename TypeImpl<Config>::bitset
+TypeImpl<Config>::BitsetType::Lub(int32_t value) {
   if (value >= 0x40000000) {
     return i::SmiValuesAre31Bits() ? kOtherUnsigned31 : kUnsignedSmall;
   }
@@ -155,7 +162,8 @@ int TypeImpl<Config>::BitsetType::Lub(int32_t value) {
 
 
 template<class Config>
-int TypeImpl<Config>::BitsetType::Lub(uint32_t value) {
+typename TypeImpl<Config>::bitset
+TypeImpl<Config>::BitsetType::Lub(uint32_t value) {
   DisallowHeapAllocation no_allocation;
   if (value >= 0x80000000u) return kOtherUnsigned32;
   if (value >= 0x40000000u) {
@@ -166,7 +174,8 @@ int TypeImpl<Config>::BitsetType::Lub(uint32_t value) {
 
 
 template<class Config>
-int TypeImpl<Config>::BitsetType::Lub(i::Map* map) {
+typename TypeImpl<Config>::bitset
+TypeImpl<Config>::BitsetType::Lub(i::Map* map) {
   DisallowHeapAllocation no_allocation;
   switch (map->instance_type()) {
     case STRING_TYPE:
@@ -457,8 +466,8 @@ bool TypeImpl<Config>::UnionType::Wellformed() {
 
 template<class Config>
 typename TypeImpl<Config>::TypeHandle TypeImpl<Config>::Rebound(
-    int bitset, Region* region) {
-  TypeHandle bound = BitsetType::New(bitset, region);
+    bitset bitset_bound, Region* region) {
+  TypeHandle bound = BitsetType::New(bitset_bound, region);
   if (this->IsClass()) {
     return ClassType::New(this->AsClass()->Map(), bound, region);
   } else if (this->IsConstant()) {
@@ -486,16 +495,16 @@ typename TypeImpl<Config>::TypeHandle TypeImpl<Config>::Rebound(
 
 
 template<class Config>
-int TypeImpl<Config>::BoundBy(TypeImpl* that) {
+typename TypeImpl<Config>::bitset TypeImpl<Config>::BoundBy(TypeImpl* that) {
   DCHECK(!this->IsUnion());
   if (that->IsUnion()) {
     UnionType* unioned = that->AsUnion();
     int length = unioned->Length();
-    int bitset = BitsetType::kNone;
+    bitset result = BitsetType::kNone;
     for (int i = 0; i < length; ++i) {
-      bitset |= BoundBy(unioned->Get(i)->unhandle());
+      result |= BoundBy(unioned->Get(i)->unhandle());
     }
-    return bitset;
+    return result;
   } else if (that->IsClass() && this->IsClass() &&
       *this->AsClass()->Map() == *that->AsClass()->Map()) {
     return that->BitsetLub();
@@ -515,7 +524,7 @@ int TypeImpl<Config>::BoundBy(TypeImpl* that) {
 
 template<class Config>
 int TypeImpl<Config>::IndexInUnion(
-    int bound, UnionHandle unioned, int current_size) {
+    bitset bound, UnionHandle unioned, int current_size) {
   DCHECK(!this->IsUnion());
   for (int i = 0; i < current_size; ++i) {
     TypeHandle that = unioned->Get(i);
@@ -545,7 +554,7 @@ int TypeImpl<Config>::ExtendUnion(
     UnionHandle result, int size, TypeHandle type,
     TypeHandle other, bool is_intersect, Region* region) {
   if (type->IsUnion()) {
-    UnionHandle unioned = handle(type->AsUnion());
+    UnionHandle unioned = Config::template cast<UnionType>(type);
     for (int i = 0; i < unioned->Length(); ++i) {
       TypeHandle type_i = unioned->Get(i);
       DCHECK(i == 0 || !(type_i->IsBitset() || type_i->Is(unioned->Get(0))));
@@ -556,10 +565,10 @@ int TypeImpl<Config>::ExtendUnion(
   } else if (!type->IsBitset()) {
     DCHECK(type->IsClass() || type->IsConstant() || type->IsRange() ||
            type->IsContext() || type->IsArray() || type->IsFunction());
-    int inherent_bound = type->InherentBitsetLub();
-    int old_bound = type->BitsetLub();
-    int other_bound = type->BoundBy(other->unhandle()) & inherent_bound;
-    int new_bound =
+    bitset inherent_bound = type->InherentBitsetLub();
+    bitset old_bound = type->BitsetLub();
+    bitset other_bound = type->BoundBy(other->unhandle()) & inherent_bound;
+    bitset new_bound =
         is_intersect ? (old_bound & other_bound) : (old_bound | other_bound);
     if (new_bound != BitsetType::kNone) {
       int i = type->IndexInUnion(new_bound, result, size);
@@ -568,7 +577,7 @@ int TypeImpl<Config>::ExtendUnion(
       } else if (result->Get(i)->IsBitset()) {
         return size;  // Already fully subsumed.
       } else {
-        int type_i_bound = result->Get(i)->BitsetLub();
+        bitset type_i_bound = result->Get(i)->BitsetLub();
         new_bound |= type_i_bound;
         if (new_bound == type_i_bound) return size;
       }
@@ -607,14 +616,14 @@ typename TypeImpl<Config>::TypeHandle TypeImpl<Config>::Union(
   if (!type2->IsBitset()) {
     size += (type2->IsUnion() ? type2->AsUnion()->Length() : 1);
   }
-  int bitset = type1->BitsetGlb() | type2->BitsetGlb();
-  if (bitset != BitsetType::kNone) ++size;
+  bitset bits = type1->BitsetGlb() | type2->BitsetGlb();
+  if (bits != BitsetType::kNone) ++size;
   DCHECK(size >= 1);
 
   UnionHandle unioned = UnionType::New(size, region);
   size = 0;
-  if (bitset != BitsetType::kNone) {
-    unioned->Set(size++, BitsetType::New(bitset, region));
+  if (bits != BitsetType::kNone) {
+    unioned->Set(size++, BitsetType::New(bits, region));
   }
   size = ExtendUnion(unioned, size, type1, type2, false, region);
   size = ExtendUnion(unioned, size, type2, type1, false, region);
@@ -656,14 +665,14 @@ typename TypeImpl<Config>::TypeHandle TypeImpl<Config>::Intersect(
   if (!type2->IsBitset()) {
     size += (type2->IsUnion() ? type2->AsUnion()->Length() : 1);
   }
-  int bitset = type1->BitsetGlb() & type2->BitsetGlb();
-  if (bitset != BitsetType::kNone) ++size;
+  bitset bits = type1->BitsetGlb() & type2->BitsetGlb();
+  if (bits != BitsetType::kNone) ++size;
   DCHECK(size >= 1);
 
   UnionHandle unioned = UnionType::New(size, region);
   size = 0;
-  if (bitset != BitsetType::kNone) {
-    unioned->Set(size++, BitsetType::New(bitset, region));
+  if (bits != BitsetType::kNone) {
+    unioned->Set(size++, BitsetType::New(bits, region));
   }
   size = ExtendUnion(unioned, size, type1, type2, true, region);
   size = ExtendUnion(unioned, size, type2, type1, true, region);
@@ -772,7 +781,7 @@ void TypeImpl<Config>::Iterator<T>::Advance() {
   DisallowHeapAllocation no_allocation;
   ++index_;
   if (type_->IsUnion()) {
-    UnionHandle unioned = handle(type_->AsUnion());
+    UnionHandle unioned = Config::template cast<UnionType>(type_);
     for (; index_ < unioned->Length(); ++index_) {
       if (matches(unioned->Get(index_))) return;
     }
@@ -841,8 +850,8 @@ typename TypeImpl<Config>::TypeHandle TypeImpl<Config>::Convert(
 // Printing.
 
 template<class Config>
-const char* TypeImpl<Config>::BitsetType::Name(int bitset) {
-  switch (bitset) {
+const char* TypeImpl<Config>::BitsetType::Name(bitset bits) {
+  switch (bits) {
     case REPRESENTATION(kAny): return "Any";
     #define RETURN_NAMED_REPRESENTATION_TYPE(type, value) \
     case REPRESENTATION(k##type): return #type;
@@ -862,15 +871,15 @@ const char* TypeImpl<Config>::BitsetType::Name(int bitset) {
 
 template <class Config>
 void TypeImpl<Config>::BitsetType::Print(OStream& os,  // NOLINT
-                                         int bitset) {
+                                         bitset bits) {
   DisallowHeapAllocation no_allocation;
-  const char* name = Name(bitset);
+  const char* name = Name(bits);
   if (name != NULL) {
     os << name;
     return;
   }
 
-  static const int named_bitsets[] = {
+  static const bitset named_bitsets[] = {
 #define BITSET_CONSTANT(type, value) REPRESENTATION(k##type),
       REPRESENTATION_BITSET_TYPE_LIST(BITSET_CONSTANT)
 #undef BITSET_CONSTANT
@@ -882,16 +891,16 @@ void TypeImpl<Config>::BitsetType::Print(OStream& os,  // NOLINT
 
   bool is_first = true;
   os << "(";
-  for (int i(arraysize(named_bitsets) - 1); bitset != 0 && i >= 0; --i) {
-    int subset = named_bitsets[i];
-    if ((bitset & subset) == subset) {
+  for (int i(arraysize(named_bitsets) - 1); bits != 0 && i >= 0; --i) {
+    bitset subset = named_bitsets[i];
+    if ((bits & subset) == subset) {
       if (!is_first) os << " | ";
       is_first = false;
       os << Name(subset);
-      bitset -= subset;
+      bits -= subset;
     }
   }
-  DCHECK(bitset == 0);
+  DCHECK(bits == 0);
   os << ")";
 }
 

src/types.h

@@ -122,8 +122,8 @@ namespace internal {
 // IMPLEMENTATION
 //
 // Internally, all 'primitive' types, and their unions, are represented as
-// bitsets. Class is a heap pointer to the respective map. Only Constant's, or
-// unions containing Class'es or Constant's, currently require allocation.
+// bitsets. Bit 0 is reserved for tagging. Class is a heap pointer to the
+// respective map. Only structured types require allocation.
 // Note that the bitset representation is closed under both Union and Intersect.
 //
 // There are two type representations, using different allocation:
@@ -139,24 +139,23 @@ namespace internal {
 // Values for bitset types
 
 #define MASK_BITSET_TYPE_LIST(V) \
-  V(Representation, static_cast<int>(0xffc00000)) \
-  V(Semantic,       static_cast<int>(0x003fffff))
+  V(Representation, 0xff800000u) \
+  V(Semantic,       0x007ffffeu)
 
 #define REPRESENTATION(k) ((k) & BitsetType::kRepresentation)
 #define SEMANTIC(k)       ((k) & BitsetType::kSemantic)
 
 #define REPRESENTATION_BITSET_TYPE_LIST(V) \
   V(None,             0)                   \
-  V(UntaggedInt1,     1 << 22 | kSemantic) \
-  V(UntaggedInt8,     1 << 23 | kSemantic) \
-  V(UntaggedInt16,    1 << 24 | kSemantic) \
-  V(UntaggedInt32,    1 << 25 | kSemantic) \
-  V(UntaggedFloat32,  1 << 26 | kSemantic) \
-  V(UntaggedFloat64,  1 << 27 | kSemantic) \
-  V(UntaggedPtr,      1 << 28 | kSemantic) \
-  V(TaggedInt,        1 << 29 | kSemantic) \
-  /* MSB has to be sign-extended */        \
-  V(TaggedPtr,        static_cast<int>(~0u << 30) | kSemantic) \
+  V(UntaggedInt1,     1 << 23 | kSemantic) \
+  V(UntaggedInt8,     1 << 24 | kSemantic) \
+  V(UntaggedInt16,    1 << 25 | kSemantic) \
+  V(UntaggedInt32,    1 << 26 | kSemantic) \
+  V(UntaggedFloat32,  1 << 27 | kSemantic) \
+  V(UntaggedFloat64,  1 << 28 | kSemantic) \
+  V(UntaggedPtr,      1 << 29 | kSemantic) \
+  V(TaggedInt,        1 << 30 | kSemantic) \
+  V(TaggedPtr,        1 << 31 | kSemantic) \
   \
   V(UntaggedInt,      kUntaggedInt1 | kUntaggedInt8 |      \
                       kUntaggedInt16 | kUntaggedInt32)     \
@@ -166,28 +165,28 @@ namespace internal {
   V(Tagged,           kTaggedInt | kTaggedPtr)
 
 #define SEMANTIC_BITSET_TYPE_LIST(V) \
-  V(Null,                1 << 0  | REPRESENTATION(kTaggedPtr)) \
-  V(Undefined,           1 << 1  | REPRESENTATION(kTaggedPtr)) \
-  V(Boolean,             1 << 2  | REPRESENTATION(kTaggedPtr)) \
-  V(UnsignedSmall,       1 << 3  | REPRESENTATION(kTagged | kUntaggedNumber)) \
-  V(OtherSignedSmall,    1 << 4  | REPRESENTATION(kTagged | kUntaggedNumber)) \
-  V(OtherUnsigned31,     1 << 5  | REPRESENTATION(kTagged | kUntaggedNumber)) \
-  V(OtherUnsigned32,     1 << 6  | REPRESENTATION(kTagged | kUntaggedNumber)) \
-  V(OtherSigned32,       1 << 7  | REPRESENTATION(kTagged | kUntaggedNumber)) \
-  V(MinusZero,           1 << 8  | REPRESENTATION(kTagged | kUntaggedNumber)) \
-  V(NaN,                 1 << 9  | REPRESENTATION(kTagged | kUntaggedNumber)) \
-  V(OtherNumber,         1 << 10 | REPRESENTATION(kTagged | kUntaggedNumber)) \
-  V(Symbol,              1 << 11 | REPRESENTATION(kTaggedPtr)) \
-  V(InternalizedString,  1 << 12 | REPRESENTATION(kTaggedPtr)) \
-  V(OtherString,         1 << 13 | REPRESENTATION(kTaggedPtr)) \
-  V(Undetectable,        1 << 14 | REPRESENTATION(kTaggedPtr)) \
-  V(Array,               1 << 15 | REPRESENTATION(kTaggedPtr)) \
-  V(Buffer,              1 << 16 | REPRESENTATION(kTaggedPtr)) \
-  V(Function,            1 << 17 | REPRESENTATION(kTaggedPtr)) \
-  V(RegExp,              1 << 18 | REPRESENTATION(kTaggedPtr)) \
-  V(OtherObject,         1 << 19 | REPRESENTATION(kTaggedPtr)) \
-  V(Proxy,               1 << 20 | REPRESENTATION(kTaggedPtr)) \
-  V(Internal,            1 << 21 | REPRESENTATION(kTagged | kUntagged)) \
+  V(Null,                1 << 1  | REPRESENTATION(kTaggedPtr)) \
+  V(Undefined,           1 << 2  | REPRESENTATION(kTaggedPtr)) \
+  V(Boolean,             1 << 3  | REPRESENTATION(kTaggedPtr)) \
+  V(UnsignedSmall,       1 << 4  | REPRESENTATION(kTagged | kUntaggedNumber)) \
+  V(OtherSignedSmall,    1 << 5  | REPRESENTATION(kTagged | kUntaggedNumber)) \
+  V(OtherUnsigned31,     1 << 6  | REPRESENTATION(kTagged | kUntaggedNumber)) \
+  V(OtherUnsigned32,     1 << 7  | REPRESENTATION(kTagged | kUntaggedNumber)) \
+  V(OtherSigned32,       1 << 8  | REPRESENTATION(kTagged | kUntaggedNumber)) \
+  V(MinusZero,           1 << 9  | REPRESENTATION(kTagged | kUntaggedNumber)) \
+  V(NaN,                 1 << 10 | REPRESENTATION(kTagged | kUntaggedNumber)) \
+  V(OtherNumber,         1 << 11 | REPRESENTATION(kTagged | kUntaggedNumber)) \
+  V(Symbol,              1 << 12 | REPRESENTATION(kTaggedPtr)) \
+  V(InternalizedString,  1 << 13 | REPRESENTATION(kTaggedPtr)) \
+  V(OtherString,         1 << 14 | REPRESENTATION(kTaggedPtr)) \
+  V(Undetectable,        1 << 15 | REPRESENTATION(kTaggedPtr)) \
+  V(Array,               1 << 16 | REPRESENTATION(kTaggedPtr)) \
+  V(Buffer,              1 << 17 | REPRESENTATION(kTaggedPtr)) \
+  V(Function,            1 << 18 | REPRESENTATION(kTaggedPtr)) \
+  V(RegExp,              1 << 19 | REPRESENTATION(kTaggedPtr)) \
+  V(OtherObject,         1 << 20 | REPRESENTATION(kTaggedPtr)) \
+  V(Proxy,               1 << 21 | REPRESENTATION(kTaggedPtr)) \
+  V(Internal,            1 << 22 | REPRESENTATION(kTagged | kUntagged)) \
   \
   V(SignedSmall,         kUnsignedSmall | kOtherSignedSmall) \
   V(Signed32,            kSignedSmall | kOtherUnsigned31 | kOtherSigned32) \
@@ -207,7 +206,7 @@ namespace internal {
   V(Receiver,            kObject | kProxy) \
   V(NonNumber,           kBoolean | kName | kNull | kReceiver | \
                          kUndefined | kInternal) \
-  V(Any,                 -1)
+  V(Any,                 0xfffffffeu)
 
 #define BITSET_TYPE_LIST(V) \
   MASK_BITSET_TYPE_LIST(V) \
@@ -229,11 +228,11 @@ namespace internal {
 //   static bool is_bitset(Type*);
 //   static bool is_class(Type*);
 //   static bool is_struct(Type*, int tag);
-//   static int as_bitset(Type*);
+//   static bitset as_bitset(Type*);
 //   static i::Handle<i::Map> as_class(Type*);
 //   static Handle<Struct>::type as_struct(Type*);
-//   static Type* from_bitset(int bitset);
-//   static Handle<Type>::type from_bitset(int bitset, Region*);
+//   static Type* from_bitset(bitset);
+//   static Handle<Type>::type from_bitset(bitset, Region*);
 //   static Handle<Type>::type from_class(i::Handle<Map>, Region*);
 //   static Handle<Type>::type from_struct(Handle<Struct>::type, int tag);
 //   static Handle<Struct>::type struct_create(int tag, int length, Region*);
@@ -252,9 +251,10 @@ class TypeImpl : public Config::Base {
  public:
   // Auxiliary types.
 
-  class BitsetType;      // Internal
-  class StructuralType;  // Internal
-  class UnionType;       // Internal
+  typedef uintptr_t bitset;  // Internal
+  class BitsetType;          // Internal
+  class StructuralType;      // Internal
+  class UnionType;           // Internal
 
   class ClassType;
   class ConstantType;
@@ -457,7 +457,7 @@ class TypeImpl : public Config::Base {
   bool IsBitset() { return Config::is_bitset(this); }
   bool IsUnion() { return Config::is_struct(this, StructuralType::kUnionTag); }
 
-  int AsBitset() {
+  bitset AsBitset() {
     DCHECK(this->IsBitset());
     return static_cast<BitsetType*>(this)->Bitset();
   }
@@ -465,15 +465,15 @@ class TypeImpl : public Config::Base {
 
   // Auxiliary functions.
 
-  int BitsetGlb() { return BitsetType::Glb(this); }
-  int BitsetLub() { return BitsetType::Lub(this); }
-  int InherentBitsetLub() { return BitsetType::InherentLub(this); }
+  bitset BitsetGlb() { return BitsetType::Glb(this); }
+  bitset BitsetLub() { return BitsetType::Lub(this); }
+  bitset InherentBitsetLub() { return BitsetType::InherentLub(this); }
 
   bool SlowIs(TypeImpl* that);
 
-  TypeHandle Rebound(int bitset, Region* region);
-  int BoundBy(TypeImpl* that);
-  int IndexInUnion(int bound, UnionHandle unioned, int current_size);
+  TypeHandle Rebound(bitset bound, Region* region);
+  bitset BoundBy(TypeImpl* that);
+  int IndexInUnion(bitset bound, UnionHandle unioned, int current_size);
   static int ExtendUnion(
       UnionHandle unioned, int current_size, TypeHandle t,
       TypeHandle other, bool is_intersect, Region* region);
@@ -495,35 +495,35 @@ class TypeImpl<Config>::BitsetType : public TypeImpl<Config> {
     kUnusedEOL = 0
   };
 
-  int Bitset() { return Config::as_bitset(this); }
+  bitset Bitset() { return Config::as_bitset(this); }
 
-  static TypeImpl* New(int bitset) {
-    return static_cast<BitsetType*>(Config::from_bitset(bitset));
+  static TypeImpl* New(bitset bits) {
+    return static_cast<BitsetType*>(Config::from_bitset(bits));
   }
-  static TypeHandle New(int bitset, Region* region) {
-    return Config::from_bitset(bitset, region);
+  static TypeHandle New(bitset bits, Region* region) {
+    return Config::from_bitset(bits, region);
   }
 
-  static bool IsInhabited(int bitset) {
-    return (bitset & kRepresentation) && (bitset & kSemantic);
+  static bool IsInhabited(bitset bits) {
+    return (bits & kRepresentation) && (bits & kSemantic);
   }
 
-  static bool Is(int bitset1, int bitset2) {
-    return (bitset1 | bitset2) == bitset2;
+  static bool Is(bitset bits1, bitset bits2) {
+    return (bits1 | bits2) == bits2;
   }
 
-  static int Glb(TypeImpl* type);  // greatest lower bound that's a bitset
-  static int Lub(TypeImpl* type);  // least upper bound that's a bitset
-  static int Lub(i::Object* value);
-  static int Lub(double value);
-  static int Lub(int32_t value);
-  static int Lub(uint32_t value);
-  static int Lub(i::Map* map);
-  static int Lub(double min, double max);
-  static int InherentLub(TypeImpl* type);
+  static bitset Glb(TypeImpl* type);  // greatest lower bound that's a bitset
+  static bitset Lub(TypeImpl* type);  // least upper bound that's a bitset
+  static bitset Lub(i::Object* value);
+  static bitset Lub(double value);
+  static bitset Lub(int32_t value);
+  static bitset Lub(uint32_t value);
+  static bitset Lub(i::Map* map);
+  static bitset Lub(double min, double max);
+  static bitset InherentLub(TypeImpl* type);
 
-  static const char* Name(int bitset);
-  static void Print(OStream& os, int bitset);  // NOLINT
+  static const char* Name(bitset);
+  static void Print(OStream& os, bitset);  // NOLINT
   using TypeImpl::PrintTo;
 };
 
@@ -866,12 +866,12 @@ struct ZoneTypeConfig {
   static inline bool is_class(Type* type);
   static inline bool is_struct(Type* type, int tag);
 
-  static inline int as_bitset(Type* type);
+  static inline Type::bitset as_bitset(Type* type);
   static inline i::Handle<i::Map> as_class(Type* type);
   static inline Struct* as_struct(Type* type);
 
-  static inline Type* from_bitset(int bitset);
-  static inline Type* from_bitset(int bitset, Zone* zone);
+  static inline Type* from_bitset(Type::bitset);
+  static inline Type* from_bitset(Type::bitset, Zone* zone);
   static inline Type* from_class(i::Handle<i::Map> map, Zone* zone);
   static inline Type* from_struct(Struct* structured);
 
@@ -913,12 +913,12 @@ struct HeapTypeConfig {
   static inline bool is_class(Type* type);
   static inline bool is_struct(Type* type, int tag);
 
-  static inline int as_bitset(Type* type);
+  static inline Type::bitset as_bitset(Type* type);
   static inline i::Handle<i::Map> as_class(Type* type);
   static inline i::Handle<Struct> as_struct(Type* type);
 
-  static inline Type* from_bitset(int bitset);
-  static inline i::Handle<Type> from_bitset(int bitset, Isolate* isolate);
+  static inline Type* from_bitset(Type::bitset);
+  static inline i::Handle<Type> from_bitset(Type::bitset, Isolate* isolate);
   static inline i::Handle<Type> from_class(
       i::Handle<i::Map> map, Isolate* isolate);
   static inline i::Handle<Type> from_struct(i::Handle<Struct> structure);