| // 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 V8_TYPES_H_ |
| #define V8_TYPES_H_ |
| |
| #include "handles.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| // SUMMARY |
| // |
| // A simple type system for compiler-internal use. It is based entirely on |
| // union types, and all subtyping hence amounts to set inclusion. Besides the |
| // obvious primitive types and some predefined unions, the type language also |
| // can express class types (a.k.a. specific maps) and singleton types (i.e., |
| // concrete constants). |
| // |
| // Types consist of two dimensions: semantic (value range) and representation. |
| // Both are related through subtyping. |
| // |
| // SEMANTIC DIMENSION |
| // |
| // The following equations and inequations hold for the semantic axis: |
| // |
| // None <= T |
| // T <= Any |
| // |
| // Number = Signed32 \/ Unsigned32 \/ Double |
| // Smi <= Signed32 |
| // Name = String \/ Symbol |
| // UniqueName = InternalizedString \/ Symbol |
| // InternalizedString < String |
| // |
| // Receiver = Object \/ Proxy |
| // Array < Object |
| // Function < Object |
| // RegExp < Object |
| // Undetectable < Object |
| // Detectable = Receiver \/ Number \/ Name - Undetectable |
| // |
| // Class(map) < T iff instance_type(map) < T |
| // Constant(x) < T iff instance_type(map(x)) < T |
| // |
| // Note that Constant(x) < Class(map(x)) does _not_ hold, since x's map can |
| // change! (Its instance type cannot, however.) |
| // TODO(rossberg): the latter is not currently true for proxies, because of fix, |
| // but will hold once we implement direct proxies. |
| // However, we also define a 'temporal' variant of the subtyping relation that |
| // considers the _current_ state only, i.e., Constant(x) <_now Class(map(x)). |
| // |
| // REPRESENTATIONAL DIMENSION |
| // |
| // For the representation axis, the following holds: |
| // |
| // None <= R |
| // R <= Any |
| // |
| // UntaggedInt <= UntaggedInt8 \/ UntaggedInt16 \/ UntaggedInt32) |
| // UntaggedFloat <= UntaggedFloat32 \/ UntaggedFloat64 |
| // UntaggedNumber <= UntaggedInt \/ UntaggedFloat |
| // Untagged <= UntaggedNumber \/ UntaggedPtr |
| // Tagged <= TaggedInt \/ TaggedPtr |
| // |
| // Subtyping relates the two dimensions, for example: |
| // |
| // Number <= Tagged \/ UntaggedNumber |
| // Object <= TaggedPtr \/ UntaggedPtr |
| // |
| // That holds because the semantic type constructors defined by the API create |
| // types that allow for all possible representations, and dually, the ones for |
| // representation types initially include all semantic ranges. Representations |
| // can then e.g. be narrowed for a given semantic type using intersection: |
| // |
| // SignedSmall /\ TaggedInt (a 'smi') |
| // Number /\ TaggedPtr (a heap number) |
| // |
| // PREDICATES |
| // |
| // There are two main functions for testing types: |
| // |
| // T1->Is(T2) -- tests whether T1 is included in T2 (i.e., T1 <= T2) |
| // T1->Maybe(T2) -- tests whether T1 and T2 overlap (i.e., T1 /\ T2 =/= 0) |
| // |
| // Typically, the former is to be used to select representations (e.g., via |
| // T->Is(SignedSmall())), and the latter to check whether a specific case needs |
| // handling (e.g., via T->Maybe(Number())). |
| // |
| // There is no functionality to discover whether a type is a leaf in the |
| // lattice. That is intentional. It should always be possible to refine the |
| // lattice (e.g., splitting up number types further) without invalidating any |
| // existing assumptions or tests. |
| // Consequently, do not use pointer equality for type tests, always use Is! |
| // |
| // The NowIs operator implements state-sensitive subtying, as described above. |
| // Any compilation decision based on such temporary properties requires runtime |
| // guarding! |
| // |
| // PROPERTIES |
| // |
| // Various formal properties hold for constructors, operators, and predicates |
| // over types. For example, constructors are injective, subtyping is a partial |
| // order, and union and intersection satisfy the usual algebraic properties. |
| // |
| // See test/cctest/test-types.cc for a comprehensive executable specification, |
| // especially with respect to the proeprties of the more exotic 'temporal' |
| // constructors and predicates (those prefixed 'Now'). |
| // |
| // 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. |
| // Note that the bitset representation is closed under both Union and Intersect. |
| // |
| // There are two type representations, using different allocation: |
| // |
| // - class Type (zone-allocated, for compiler and concurrent compilation) |
| // - class HeapType (heap-allocated, for persistent types) |
| // |
| // Both provide the same API, and the Convert method can be used to interconvert |
| // them. For zone types, no query method touches the heap, only constructors do. |
| |
| |
| #define MASK_BITSET_TYPE_LIST(V) \ |
| V(Representation, static_cast<int>(0xff800000)) \ |
| V(Semantic, static_cast<int>(0x007fffff)) |
| |
| #define REPRESENTATION(k) ((k) & kRepresentation) |
| #define SEMANTIC(k) ((k) & kSemantic) |
| |
| #define REPRESENTATION_BITSET_TYPE_LIST(V) \ |
| V(None, 0) \ |
| 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) \ |
| V(TaggedPtr, -1 << 30 | kSemantic) /* MSB has to be sign-extended */ \ |
| \ |
| V(UntaggedInt, kUntaggedInt8 | kUntaggedInt16 | kUntaggedInt32) \ |
| V(UntaggedFloat, kUntaggedFloat32 | kUntaggedFloat64) \ |
| V(UntaggedNumber, kUntaggedInt | kUntaggedFloat) \ |
| V(Untagged, kUntaggedNumber | kUntaggedPtr) \ |
| 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(SignedSmall, 1 << 3 | REPRESENTATION(kTagged | kUntaggedNumber)) \ |
| V(OtherSigned32, 1 << 4 | REPRESENTATION(kTagged | kUntaggedNumber)) \ |
| V(Unsigned32, 1 << 5 | REPRESENTATION(kTagged | kUntaggedNumber)) \ |
| V(Float, 1 << 6 | REPRESENTATION(kTagged | kUntaggedNumber)) \ |
| V(Symbol, 1 << 7 | REPRESENTATION(kTaggedPtr)) \ |
| V(InternalizedString, 1 << 8 | REPRESENTATION(kTaggedPtr)) \ |
| V(OtherString, 1 << 9 | REPRESENTATION(kTaggedPtr)) \ |
| V(Undetectable, 1 << 10 | REPRESENTATION(kTaggedPtr)) \ |
| V(Array, 1 << 11 | REPRESENTATION(kTaggedPtr)) \ |
| V(Function, 1 << 12 | REPRESENTATION(kTaggedPtr)) \ |
| V(RegExp, 1 << 13 | REPRESENTATION(kTaggedPtr)) \ |
| V(OtherObject, 1 << 14 | REPRESENTATION(kTaggedPtr)) \ |
| V(Proxy, 1 << 15 | REPRESENTATION(kTaggedPtr)) \ |
| V(Internal, 1 << 16 | REPRESENTATION(kTagged | kUntagged)) \ |
| \ |
| V(Signed32, kSignedSmall | kOtherSigned32) \ |
| V(Number, kSigned32 | kUnsigned32 | kFloat) \ |
| V(String, kInternalizedString | kOtherString) \ |
| V(UniqueName, kSymbol | kInternalizedString) \ |
| V(Name, kSymbol | kString) \ |
| V(NumberOrString, kNumber | kString) \ |
| V(DetectableObject, kArray | kFunction | kRegExp | kOtherObject) \ |
| V(DetectableReceiver, kDetectableObject | kProxy) \ |
| V(Detectable, kDetectableReceiver | kNumber | kName) \ |
| V(Object, kDetectableObject | kUndetectable) \ |
| V(Receiver, kObject | kProxy) \ |
| V(NonNumber, kBoolean | kName | kNull | kReceiver | \ |
| kUndefined | kInternal) \ |
| V(Any, -1) |
| |
| #define BITSET_TYPE_LIST(V) \ |
| MASK_BITSET_TYPE_LIST(V) \ |
| REPRESENTATION_BITSET_TYPE_LIST(V) \ |
| SEMANTIC_BITSET_TYPE_LIST(V) |
| |
| |
| // struct Config { |
| // typedef Base; |
| // typedef Struct; |
| // typedef Region; |
| // template<class> struct Handle { typedef type; } // No template typedefs... |
| // static Handle<Type>::type handle(Type* type); // !is_bitset(type) |
| // static bool is_bitset(Type*); |
| // static bool is_class(Type*); |
| // static bool is_constant(Type*); |
| // static bool is_struct(Type*); |
| // static int as_bitset(Type*); |
| // static i::Handle<i::Map> as_class(Type*); |
| // static i::Handle<i::Object> as_constant(Type*); |
| // static Handle<Struct>::type as_struct(Type*); |
| // static Type* from_bitset(int bitset); |
| // static Handle<Type>::type from_bitset(int bitset, Region*); |
| // static Handle<Type>::type from_class(i::Handle<Map>, int lub, Region*); |
| // static Handle<Type>::type from_constant(i::Handle<Object>, int, Region*); |
| // static Handle<Type>::type from_struct(Handle<Struct>::type); |
| // static Handle<Struct>::type struct_create(int tag, int length, Region*); |
| // static void struct_shrink(Handle<Struct>::type, int length); |
| // static int struct_tag(Handle<Struct>::type); |
| // static int struct_length(Handle<Struct>::type); |
| // static Handle<Type>::type struct_get(Handle<Struct>::type, int); |
| // static void struct_set(Handle<Struct>::type, int, Handle<Type>::type); |
| // static int lub_bitset(Type*); |
| // } |
| template<class Config> |
| class TypeImpl : public Config::Base { |
| public: |
| typedef typename Config::template Handle<TypeImpl>::type TypeHandle; |
| typedef typename Config::Region Region; |
| |
| #define DEFINE_TYPE_CONSTRUCTOR(type, value) \ |
| static TypeImpl* type() { return Config::from_bitset(k##type); } \ |
| static TypeHandle type(Region* region) { \ |
| return Config::from_bitset(k##type, region); \ |
| } |
| BITSET_TYPE_LIST(DEFINE_TYPE_CONSTRUCTOR) |
| #undef DEFINE_TYPE_CONSTRUCTOR |
| |
| static TypeHandle Class(i::Handle<i::Map> map, Region* region) { |
| return Config::from_class(map, LubBitset(*map), region); |
| } |
| static TypeHandle Constant(i::Handle<i::Object> value, Region* region) { |
| return Config::from_constant(value, LubBitset(*value), region); |
| } |
| |
| static TypeHandle Union(TypeHandle type1, TypeHandle type2, Region* reg); |
| static TypeHandle Intersect(TypeHandle type1, TypeHandle type2, Region* reg); |
| |
| static TypeHandle Of(i::Object* value, Region* region) { |
| return Config::from_bitset(LubBitset(value), region); |
| } |
| static TypeHandle Of(i::Handle<i::Object> value, Region* region) { |
| return Of(*value, region); |
| } |
| |
| bool IsInhabited() { |
| return !this->IsBitset() || IsInhabited(this->AsBitset()); |
| } |
| |
| bool Is(TypeImpl* that) { return this == that || this->SlowIs(that); } |
| template<class TypeHandle> |
| bool Is(TypeHandle that) { return this->Is(*that); } |
| |
| bool Maybe(TypeImpl* that); |
| template<class TypeHandle> |
| bool Maybe(TypeHandle that) { return this->Maybe(*that); } |
| |
| // Equivalent to Constant(value)->Is(this), but avoiding allocation. |
| bool Contains(i::Object* val); |
| bool Contains(i::Handle<i::Object> val) { return this->Contains(*val); } |
| |
| // State-dependent versions of Of and Is that consider subtyping between |
| // a constant and its map class. |
| static TypeHandle NowOf(i::Object* value, Region* region); |
| static TypeHandle NowOf(i::Handle<i::Object> value, Region* region) { |
| return NowOf(*value, region); |
| } |
| bool NowIs(TypeImpl* that); |
| template<class TypeHandle> |
| bool NowIs(TypeHandle that) { return this->NowIs(*that); } |
| bool NowContains(i::Object* val); |
| bool NowContains(i::Handle<i::Object> val) { return this->NowContains(*val); } |
| |
| bool IsClass() { return Config::is_class(this); } |
| bool IsConstant() { return Config::is_constant(this); } |
| i::Handle<i::Map> AsClass() { return Config::as_class(this); } |
| i::Handle<i::Object> AsConstant() { return Config::as_constant(this); } |
| |
| int NumClasses(); |
| int NumConstants(); |
| |
| template<class T> |
| class Iterator { |
| public: |
| bool Done() const { return index_ < 0; } |
| i::Handle<T> Current(); |
| void Advance(); |
| |
| private: |
| template<class> friend class TypeImpl; |
| |
| Iterator() : index_(-1) {} |
| explicit Iterator(TypeHandle type) : type_(type), index_(-1) { |
| Advance(); |
| } |
| |
| inline bool matches(TypeHandle type); |
| inline TypeHandle get_type(); |
| |
| TypeHandle type_; |
| int index_; |
| }; |
| |
| Iterator<i::Map> Classes() { |
| if (this->IsBitset()) return Iterator<i::Map>(); |
| return Iterator<i::Map>(Config::handle(this)); |
| } |
| Iterator<i::Object> Constants() { |
| if (this->IsBitset()) return Iterator<i::Object>(); |
| return Iterator<i::Object>(Config::handle(this)); |
| } |
| |
| static TypeImpl* cast(typename Config::Base* object) { |
| TypeImpl* t = static_cast<TypeImpl*>(object); |
| ASSERT(t->IsBitset() || t->IsClass() || t->IsConstant() || t->IsUnion()); |
| return t; |
| } |
| |
| template<class OtherTypeImpl> |
| static TypeHandle Convert( |
| typename OtherTypeImpl::TypeHandle type, Region* region); |
| |
| enum PrintDimension { BOTH_DIMS, SEMANTIC_DIM, REPRESENTATION_DIM }; |
| void TypePrint(PrintDimension = BOTH_DIMS); |
| void TypePrint(FILE* out, PrintDimension = BOTH_DIMS); |
| |
| private: |
| template<class> friend class Iterator; |
| template<class> friend class TypeImpl; |
| friend struct ZoneTypeConfig; |
| friend struct HeapTypeConfig; |
| |
| enum Tag { |
| kClassTag, |
| kConstantTag, |
| kUnionTag |
| }; |
| |
| // A structured type contains a tag an a variable number of type fields. |
| // A union is a structured type with the following invariants: |
| // - its length is at least 2 |
| // - at most one field is a bitset, and it must go into index 0 |
| // - no field is a union |
| typedef typename Config::Struct Struct; |
| typedef typename Config::template Handle<Struct>::type StructHandle; |
| |
| enum { |
| #define DECLARE_TYPE(type, value) k##type = (value), |
| BITSET_TYPE_LIST(DECLARE_TYPE) |
| #undef DECLARE_TYPE |
| kUnusedEOL = 0 |
| }; |
| |
| bool IsNone() { return this == None(); } |
| bool IsAny() { return this == Any(); } |
| bool IsBitset() { return Config::is_bitset(this); } |
| bool IsStruct(Tag tag) { |
| return Config::is_struct(this) |
| && Config::struct_tag(Config::as_struct(this)) == tag; |
| } |
| bool IsUnion() { return IsStruct(kUnionTag); } |
| |
| int AsBitset() { return Config::as_bitset(this); } |
| StructHandle AsStruct(Tag tag) { |
| ASSERT(IsStruct(tag)); |
| return Config::as_struct(this); |
| } |
| StructHandle AsUnion() { return AsStruct(kUnionTag); } |
| |
| static int StructLength(StructHandle structured) { |
| return Config::struct_length(structured); |
| } |
| static TypeHandle StructGet(StructHandle structured, int i) { |
| return Config::struct_get(structured, i); |
| } |
| |
| bool SlowIs(TypeImpl* that); |
| |
| static bool IsInhabited(int bitset) { |
| return (bitset & kRepresentation) && (bitset & kSemantic); |
| } |
| |
| int LubBitset(); // least upper bound that's a bitset |
| int GlbBitset(); // greatest lower bound that's a bitset |
| |
| static int LubBitset(i::Object* value); |
| static int LubBitset(i::Map* map); |
| |
| bool InUnion(StructHandle unioned, int current_size); |
| static int ExtendUnion( |
| StructHandle unioned, TypeHandle t, int current_size); |
| static int ExtendIntersection( |
| StructHandle unioned, TypeHandle t, TypeHandle other, int current_size); |
| |
| static const char* bitset_name(int bitset); |
| static void BitsetTypePrint(FILE* out, int bitset); |
| }; |
| |
| |
| // Zone-allocated types are either (odd) integers to represent bitsets, or |
| // (even) pointers to structures for everything else. |
| struct ZoneTypeConfig { |
| typedef TypeImpl<ZoneTypeConfig> Type; |
| class Base {}; |
| typedef void* Struct; |
| typedef i::Zone Region; |
| template<class T> struct Handle { typedef T* type; }; |
| |
| static inline Type* handle(Type* type); |
| static inline bool is_bitset(Type* type); |
| static inline bool is_class(Type* type); |
| static inline bool is_constant(Type* type); |
| static inline bool is_struct(Type* type); |
| static inline int as_bitset(Type* type); |
| static inline Struct* as_struct(Type* type); |
| static inline i::Handle<i::Map> as_class(Type* type); |
| static inline i::Handle<i::Object> as_constant(Type* type); |
| static inline Type* from_bitset(int bitset); |
| static inline Type* from_bitset(int bitset, Zone* zone); |
| static inline Type* from_struct(Struct* structured); |
| static inline Type* from_class(i::Handle<i::Map> map, int lub, Zone* zone); |
| static inline Type* from_constant( |
| i::Handle<i::Object> value, int lub, Zone* zone); |
| static inline Struct* struct_create(int tag, int length, Zone* zone); |
| static inline void struct_shrink(Struct* structured, int length); |
| static inline int struct_tag(Struct* structured); |
| static inline int struct_length(Struct* structured); |
| static inline Type* struct_get(Struct* structured, int i); |
| static inline void struct_set(Struct* structured, int i, Type* type); |
| static inline int lub_bitset(Type* type); |
| }; |
| |
| typedef TypeImpl<ZoneTypeConfig> Type; |
| |
| |
| // Heap-allocated types are either smis for bitsets, maps for classes, boxes for |
| // constants, or fixed arrays for unions. |
| struct HeapTypeConfig { |
| typedef TypeImpl<HeapTypeConfig> Type; |
| typedef i::Object Base; |
| typedef i::FixedArray Struct; |
| typedef i::Isolate Region; |
| template<class T> struct Handle { typedef i::Handle<T> type; }; |
| |
| static inline i::Handle<Type> handle(Type* type); |
| static inline bool is_bitset(Type* type); |
| static inline bool is_class(Type* type); |
| static inline bool is_constant(Type* type); |
| static inline bool is_struct(Type* type); |
| static inline int as_bitset(Type* type); |
| static inline i::Handle<i::Map> as_class(Type* type); |
| static inline i::Handle<i::Object> as_constant(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 i::Handle<Type> from_class( |
| i::Handle<i::Map> map, int lub, Isolate* isolate); |
| static inline i::Handle<Type> from_constant( |
| i::Handle<i::Object> value, int lub, Isolate* isolate); |
| static inline i::Handle<Type> from_struct(i::Handle<Struct> structured); |
| static inline i::Handle<Struct> struct_create( |
| int tag, int length, Isolate* isolate); |
| static inline void struct_shrink(i::Handle<Struct> structured, int length); |
| static inline int struct_tag(i::Handle<Struct> structured); |
| static inline int struct_length(i::Handle<Struct> structured); |
| static inline i::Handle<Type> struct_get(i::Handle<Struct> structured, int i); |
| static inline void struct_set( |
| i::Handle<Struct> structured, int i, i::Handle<Type> type); |
| static inline int lub_bitset(Type* type); |
| }; |
| |
| typedef TypeImpl<HeapTypeConfig> HeapType; |
| |
| |
| // A simple struct to represent a pair of lower/upper type bounds. |
| template<class Config> |
| struct BoundsImpl { |
| typedef TypeImpl<Config> Type; |
| typedef typename Type::TypeHandle TypeHandle; |
| typedef typename Type::Region Region; |
| |
| TypeHandle lower; |
| TypeHandle upper; |
| |
| BoundsImpl() {} |
| explicit BoundsImpl(TypeHandle t) : lower(t), upper(t) {} |
| BoundsImpl(TypeHandle l, TypeHandle u) : lower(l), upper(u) { |
| ASSERT(lower->Is(upper)); |
| } |
| |
| // Unrestricted bounds. |
| static BoundsImpl Unbounded(Region* region) { |
| return BoundsImpl(Type::None(region), Type::Any(region)); |
| } |
| |
| // Meet: both b1 and b2 are known to hold. |
| static BoundsImpl Both(BoundsImpl b1, BoundsImpl b2, Region* region) { |
| TypeHandle lower = Type::Union(b1.lower, b2.lower, region); |
| TypeHandle upper = Type::Intersect(b1.upper, b2.upper, region); |
| // Lower bounds are considered approximate, correct as necessary. |
| lower = Type::Intersect(lower, upper, region); |
| return BoundsImpl(lower, upper); |
| } |
| |
| // Join: either b1 or b2 is known to hold. |
| static BoundsImpl Either(BoundsImpl b1, BoundsImpl b2, Region* region) { |
| TypeHandle lower = Type::Intersect(b1.lower, b2.lower, region); |
| TypeHandle upper = Type::Union(b1.upper, b2.upper, region); |
| return BoundsImpl(lower, upper); |
| } |
| |
| static BoundsImpl NarrowLower(BoundsImpl b, TypeHandle t, Region* region) { |
| // Lower bounds are considered approximate, correct as necessary. |
| t = Type::Intersect(t, b.upper, region); |
| TypeHandle lower = Type::Union(b.lower, t, region); |
| return BoundsImpl(lower, b.upper); |
| } |
| static BoundsImpl NarrowUpper(BoundsImpl b, TypeHandle t, Region* region) { |
| TypeHandle lower = Type::Intersect(b.lower, t, region); |
| TypeHandle upper = Type::Intersect(b.upper, t, region); |
| return BoundsImpl(lower, upper); |
| } |
| |
| bool Narrows(BoundsImpl that) { |
| return that.lower->Is(this->lower) && this->upper->Is(that.upper); |
| } |
| }; |
| |
| typedef BoundsImpl<ZoneTypeConfig> Bounds; |
| |
| } } // namespace v8::internal |
| |
| #endif // V8_TYPES_H_ |