Use unsigned type bitsets to limit undefined behaviour

src/types.h

Index: src/types.h
diff --git a/src/types.h b/src/types.h
index cca8b3167b4bb9b86773d7fcf40959490a9164f0..b593b6461850538cc248cae0885aaab43d2ebde5 100644
--- a/src/types.h
+++ b/src/types.h
@@ -139,8 +139,8 @@ 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, 0xffc00000u) \
+  V(Semantic,       0x003fffffu)
 
 #define REPRESENTATION(k) ((k) & BitsetType::kRepresentation)
 #define SEMANTIC(k)       ((k) & BitsetType::kSemantic)
@@ -155,8 +155,7 @@ namespace internal {
   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(TaggedPtr,        3u << 30 | kSemantic)  /* Sign-extend MSB */ \
   \
   V(UntaggedInt,      kUntaggedInt1 | kUntaggedInt8 |      \
                       kUntaggedInt16 | kUntaggedInt32)     \
@@ -206,7 +205,7 @@ namespace internal {
   V(Receiver,            kObject | kProxy) \
   V(NonNumber,           kBoolean | kName | kNull | kReceiver | \
                          kUndefined | kInternal) \
-  V(Any,                 -1)
+  V(Any,                 0xffffffffu)
 
 #define BITSET_TYPE_LIST(V) \
   MASK_BITSET_TYPE_LIST(V) \
@@ -228,11 +227,11 @@ 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*);
@@ -251,9 +250,10 @@ 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;
@@ -456,7 +456,7 @@ 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();
   }
@@ -464,15 +464,15 @@ 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);
@@ -494,35 +494,35 @@ 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;
 };
 
@@ -865,12 +865,12 @@ 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);
 
@@ -912,12 +912,12 @@ 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);