Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame^] | 1 | // Copyright 2014 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #ifndef V8_TYPES_H_ |
| 6 | #define V8_TYPES_H_ |
| 7 | |
| 8 | #include "src/conversions.h" |
| 9 | #include "src/factory.h" |
| 10 | #include "src/handles.h" |
| 11 | #include "src/ostreams.h" |
| 12 | |
| 13 | namespace v8 { |
| 14 | namespace internal { |
| 15 | |
| 16 | // SUMMARY |
| 17 | // |
| 18 | // A simple type system for compiler-internal use. It is based entirely on |
| 19 | // union types, and all subtyping hence amounts to set inclusion. Besides the |
| 20 | // obvious primitive types and some predefined unions, the type language also |
| 21 | // can express class types (a.k.a. specific maps) and singleton types (i.e., |
| 22 | // concrete constants). |
| 23 | // |
| 24 | // Types consist of two dimensions: semantic (value range) and representation. |
| 25 | // Both are related through subtyping. |
| 26 | // |
| 27 | // |
| 28 | // SEMANTIC DIMENSION |
| 29 | // |
| 30 | // The following equations and inequations hold for the semantic axis: |
| 31 | // |
| 32 | // None <= T |
| 33 | // T <= Any |
| 34 | // |
| 35 | // Number = Signed32 \/ Unsigned32 \/ Double |
| 36 | // Smi <= Signed32 |
| 37 | // Name = String \/ Symbol |
| 38 | // UniqueName = InternalizedString \/ Symbol |
| 39 | // InternalizedString < String |
| 40 | // |
| 41 | // Receiver = Object \/ Proxy |
| 42 | // Array < Object |
| 43 | // Function < Object |
| 44 | // RegExp < Object |
| 45 | // Undetectable < Object |
| 46 | // Detectable = Receiver \/ Number \/ Name - Undetectable |
| 47 | // |
| 48 | // Class(map) < T iff instance_type(map) < T |
| 49 | // Constant(x) < T iff instance_type(map(x)) < T |
| 50 | // Array(T) < Array |
| 51 | // Function(R, S, T0, T1, ...) < Function |
| 52 | // Context(T) < Internal |
| 53 | // |
| 54 | // Both structural Array and Function types are invariant in all parameters; |
| 55 | // relaxing this would make Union and Intersect operations more involved. |
| 56 | // There is no subtyping relation between Array, Function, or Context types |
| 57 | // and respective Constant types, since these types cannot be reconstructed |
| 58 | // for arbitrary heap values. |
| 59 | // Note also that Constant(x) < Class(map(x)) does _not_ hold, since x's map can |
| 60 | // change! (Its instance type cannot, however.) |
| 61 | // TODO(rossberg): the latter is not currently true for proxies, because of fix, |
| 62 | // but will hold once we implement direct proxies. |
| 63 | // However, we also define a 'temporal' variant of the subtyping relation that |
| 64 | // considers the _current_ state only, i.e., Constant(x) <_now Class(map(x)). |
| 65 | // |
| 66 | // |
| 67 | // REPRESENTATIONAL DIMENSION |
| 68 | // |
| 69 | // For the representation axis, the following holds: |
| 70 | // |
| 71 | // None <= R |
| 72 | // R <= Any |
| 73 | // |
| 74 | // UntaggedInt = UntaggedInt1 \/ UntaggedInt8 \/ |
| 75 | // UntaggedInt16 \/ UntaggedInt32 |
| 76 | // UntaggedFloat = UntaggedFloat32 \/ UntaggedFloat64 |
| 77 | // UntaggedNumber = UntaggedInt \/ UntaggedFloat |
| 78 | // Untagged = UntaggedNumber \/ UntaggedPtr |
| 79 | // Tagged = TaggedInt \/ TaggedPtr |
| 80 | // |
| 81 | // Subtyping relates the two dimensions, for example: |
| 82 | // |
| 83 | // Number <= Tagged \/ UntaggedNumber |
| 84 | // Object <= TaggedPtr \/ UntaggedPtr |
| 85 | // |
| 86 | // That holds because the semantic type constructors defined by the API create |
| 87 | // types that allow for all possible representations, and dually, the ones for |
| 88 | // representation types initially include all semantic ranges. Representations |
| 89 | // can then e.g. be narrowed for a given semantic type using intersection: |
| 90 | // |
| 91 | // SignedSmall /\ TaggedInt (a 'smi') |
| 92 | // Number /\ TaggedPtr (a heap number) |
| 93 | // |
| 94 | // |
| 95 | // RANGE TYPES |
| 96 | // |
| 97 | // A range type represents a continuous integer interval by its minimum and |
| 98 | // maximum value. Either value might be an infinity. |
| 99 | // |
| 100 | // Constant(v) is considered a subtype of Range(x..y) if v happens to be an |
| 101 | // integer between x and y. |
| 102 | // |
| 103 | // |
| 104 | // PREDICATES |
| 105 | // |
| 106 | // There are two main functions for testing types: |
| 107 | // |
| 108 | // T1->Is(T2) -- tests whether T1 is included in T2 (i.e., T1 <= T2) |
| 109 | // T1->Maybe(T2) -- tests whether T1 and T2 overlap (i.e., T1 /\ T2 =/= 0) |
| 110 | // |
| 111 | // Typically, the former is to be used to select representations (e.g., via |
| 112 | // T->Is(SignedSmall())), and the latter to check whether a specific case needs |
| 113 | // handling (e.g., via T->Maybe(Number())). |
| 114 | // |
| 115 | // There is no functionality to discover whether a type is a leaf in the |
| 116 | // lattice. That is intentional. It should always be possible to refine the |
| 117 | // lattice (e.g., splitting up number types further) without invalidating any |
| 118 | // existing assumptions or tests. |
| 119 | // Consequently, do not normally use Equals for type tests, always use Is! |
| 120 | // |
| 121 | // The NowIs operator implements state-sensitive subtying, as described above. |
| 122 | // Any compilation decision based on such temporary properties requires runtime |
| 123 | // guarding! |
| 124 | // |
| 125 | // |
| 126 | // PROPERTIES |
| 127 | // |
| 128 | // Various formal properties hold for constructors, operators, and predicates |
| 129 | // over types. For example, constructors are injective and subtyping is a |
| 130 | // complete partial order. |
| 131 | // |
| 132 | // See test/cctest/test-types.cc for a comprehensive executable specification, |
| 133 | // especially with respect to the properties of the more exotic 'temporal' |
| 134 | // constructors and predicates (those prefixed 'Now'). |
| 135 | // |
| 136 | // |
| 137 | // IMPLEMENTATION |
| 138 | // |
| 139 | // Internally, all 'primitive' types, and their unions, are represented as |
| 140 | // bitsets. Bit 0 is reserved for tagging. Class is a heap pointer to the |
| 141 | // respective map. Only structured types require allocation. |
| 142 | // Note that the bitset representation is closed under both Union and Intersect. |
| 143 | // |
| 144 | // There are two type representations, using different allocation: |
| 145 | // |
| 146 | // - class Type (zone-allocated, for compiler and concurrent compilation) |
| 147 | // - class HeapType (heap-allocated, for persistent types) |
| 148 | // |
| 149 | // Both provide the same API, and the Convert method can be used to interconvert |
| 150 | // them. For zone types, no query method touches the heap, only constructors do. |
| 151 | |
| 152 | |
| 153 | // ----------------------------------------------------------------------------- |
| 154 | // Values for bitset types |
| 155 | |
| 156 | #define MASK_BITSET_TYPE_LIST(V) \ |
| 157 | V(Representation, 0xff800000u) \ |
| 158 | V(Semantic, 0x007ffffeu) |
| 159 | |
| 160 | #define REPRESENTATION(k) ((k) & BitsetType::kRepresentation) |
| 161 | #define SEMANTIC(k) ((k) & BitsetType::kSemantic) |
| 162 | |
| 163 | #define REPRESENTATION_BITSET_TYPE_LIST(V) \ |
| 164 | V(None, 0) \ |
| 165 | V(UntaggedInt1, 1u << 23 | kSemantic) \ |
| 166 | V(UntaggedInt8, 1u << 24 | kSemantic) \ |
| 167 | V(UntaggedInt16, 1u << 25 | kSemantic) \ |
| 168 | V(UntaggedInt32, 1u << 26 | kSemantic) \ |
| 169 | V(UntaggedFloat32, 1u << 27 | kSemantic) \ |
| 170 | V(UntaggedFloat64, 1u << 28 | kSemantic) \ |
| 171 | V(UntaggedPtr, 1u << 29 | kSemantic) \ |
| 172 | V(TaggedInt, 1u << 30 | kSemantic) \ |
| 173 | V(TaggedPtr, 1u << 31 | kSemantic) \ |
| 174 | \ |
| 175 | V(UntaggedInt, kUntaggedInt1 | kUntaggedInt8 | \ |
| 176 | kUntaggedInt16 | kUntaggedInt32) \ |
| 177 | V(UntaggedFloat, kUntaggedFloat32 | kUntaggedFloat64) \ |
| 178 | V(UntaggedNumber, kUntaggedInt | kUntaggedFloat) \ |
| 179 | V(Untagged, kUntaggedNumber | kUntaggedPtr) \ |
| 180 | V(Tagged, kTaggedInt | kTaggedPtr) |
| 181 | |
| 182 | #define SEMANTIC_BITSET_TYPE_LIST(V) \ |
| 183 | V(Null, 1u << 1 | REPRESENTATION(kTaggedPtr)) \ |
| 184 | V(Undefined, 1u << 2 | REPRESENTATION(kTaggedPtr)) \ |
| 185 | V(Boolean, 1u << 3 | REPRESENTATION(kTaggedPtr)) \ |
| 186 | V(UnsignedSmall, 1u << 4 | REPRESENTATION(kTagged | kUntaggedNumber)) \ |
| 187 | V(OtherSignedSmall, 1u << 5 | REPRESENTATION(kTagged | kUntaggedNumber)) \ |
| 188 | V(OtherUnsigned31, 1u << 6 | REPRESENTATION(kTagged | kUntaggedNumber)) \ |
| 189 | V(OtherUnsigned32, 1u << 7 | REPRESENTATION(kTagged | kUntaggedNumber)) \ |
| 190 | V(OtherSigned32, 1u << 8 | REPRESENTATION(kTagged | kUntaggedNumber)) \ |
| 191 | V(MinusZero, 1u << 9 | REPRESENTATION(kTagged | kUntaggedNumber)) \ |
| 192 | V(NaN, 1u << 10 | REPRESENTATION(kTagged | kUntaggedNumber)) \ |
| 193 | V(OtherNumber, 1u << 11 | REPRESENTATION(kTagged | kUntaggedNumber)) \ |
| 194 | V(Symbol, 1u << 12 | REPRESENTATION(kTaggedPtr)) \ |
| 195 | V(InternalizedString, 1u << 13 | REPRESENTATION(kTaggedPtr)) \ |
| 196 | V(OtherString, 1u << 14 | REPRESENTATION(kTaggedPtr)) \ |
| 197 | V(Undetectable, 1u << 15 | REPRESENTATION(kTaggedPtr)) \ |
| 198 | V(Array, 1u << 16 | REPRESENTATION(kTaggedPtr)) \ |
| 199 | V(Buffer, 1u << 17 | REPRESENTATION(kTaggedPtr)) \ |
| 200 | V(Function, 1u << 18 | REPRESENTATION(kTaggedPtr)) \ |
| 201 | V(RegExp, 1u << 19 | REPRESENTATION(kTaggedPtr)) \ |
| 202 | V(OtherObject, 1u << 20 | REPRESENTATION(kTaggedPtr)) \ |
| 203 | V(Proxy, 1u << 21 | REPRESENTATION(kTaggedPtr)) \ |
| 204 | V(Internal, 1u << 22 | REPRESENTATION(kTagged | kUntagged)) \ |
| 205 | \ |
| 206 | V(SignedSmall, kUnsignedSmall | kOtherSignedSmall) \ |
| 207 | V(Signed32, kSignedSmall | kOtherUnsigned31 | kOtherSigned32) \ |
| 208 | V(Unsigned32, kUnsignedSmall | kOtherUnsigned31 | kOtherUnsigned32) \ |
| 209 | V(Integral32, kSigned32 | kUnsigned32) \ |
| 210 | V(OrderedNumber, kIntegral32 | kMinusZero | kOtherNumber) \ |
| 211 | V(Number, kOrderedNumber | kNaN) \ |
| 212 | V(String, kInternalizedString | kOtherString) \ |
| 213 | V(UniqueName, kSymbol | kInternalizedString) \ |
| 214 | V(Name, kSymbol | kString) \ |
| 215 | V(NumberOrString, kNumber | kString) \ |
| 216 | V(Primitive, kNumber | kName | kBoolean | kNull | kUndefined) \ |
| 217 | V(DetectableObject, kArray | kFunction | kRegExp | kOtherObject) \ |
| 218 | V(DetectableReceiver, kDetectableObject | kProxy) \ |
| 219 | V(Detectable, kDetectableReceiver | kNumber | kName) \ |
| 220 | V(Object, kDetectableObject | kUndetectable) \ |
| 221 | V(Receiver, kObject | kProxy) \ |
| 222 | V(NonNumber, kBoolean | kName | kNull | kReceiver | \ |
| 223 | kUndefined | kInternal) \ |
| 224 | V(Any, 0xfffffffeu) |
| 225 | |
| 226 | /* |
| 227 | * The following diagrams show how integers (in the mathematical sense) are |
| 228 | * divided among the different atomic numerical types. |
| 229 | * |
| 230 | * If SmiValuesAre31Bits(): |
| 231 | * |
| 232 | * ON OS32 OSS US OU31 OU32 ON |
| 233 | * ______[_______[_______[_______[_______[_______[_______ |
| 234 | * -2^31 -2^30 0 2^30 2^31 2^32 |
| 235 | * |
| 236 | * Otherwise: |
| 237 | * |
| 238 | * ON OSS US OU32 ON |
| 239 | * ______[_______________[_______________[_______[_______ |
| 240 | * -2^31 0 2^31 2^32 |
| 241 | * |
| 242 | * |
| 243 | * E.g., OtherUnsigned32 (OU32) covers all integers from 2^31 to 2^32-1. |
| 244 | * |
| 245 | */ |
| 246 | |
| 247 | #define PROPER_BITSET_TYPE_LIST(V) \ |
| 248 | REPRESENTATION_BITSET_TYPE_LIST(V) \ |
| 249 | SEMANTIC_BITSET_TYPE_LIST(V) |
| 250 | |
| 251 | #define BITSET_TYPE_LIST(V) \ |
| 252 | MASK_BITSET_TYPE_LIST(V) \ |
| 253 | PROPER_BITSET_TYPE_LIST(V) |
| 254 | |
| 255 | |
| 256 | // ----------------------------------------------------------------------------- |
| 257 | // The abstract Type class, parameterized over the low-level representation. |
| 258 | |
| 259 | // struct Config { |
| 260 | // typedef TypeImpl<Config> Type; |
| 261 | // typedef Base; |
| 262 | // typedef Struct; |
| 263 | // typedef Region; |
| 264 | // template<class> struct Handle { typedef type; } // No template typedefs... |
| 265 | // template<class T> static Handle<T>::type handle(T* t); // !is_bitset(t) |
| 266 | // template<class T> static Handle<T>::type cast(Handle<Type>::type); |
| 267 | // static bool is_bitset(Type*); |
| 268 | // static bool is_class(Type*); |
| 269 | // static bool is_struct(Type*, int tag); |
| 270 | // static bitset as_bitset(Type*); |
| 271 | // static i::Handle<i::Map> as_class(Type*); |
| 272 | // static Handle<Struct>::type as_struct(Type*); |
| 273 | // static Type* from_bitset(bitset); |
| 274 | // static Handle<Type>::type from_bitset(bitset, Region*); |
| 275 | // static Handle<Type>::type from_class(i::Handle<Map>, Region*); |
| 276 | // static Handle<Type>::type from_struct(Handle<Struct>::type, int tag); |
| 277 | // static Handle<Struct>::type struct_create(int tag, int length, Region*); |
| 278 | // static void struct_shrink(Handle<Struct>::type, int length); |
| 279 | // static int struct_tag(Handle<Struct>::type); |
| 280 | // static int struct_length(Handle<Struct>::type); |
| 281 | // static Handle<Type>::type struct_get(Handle<Struct>::type, int); |
| 282 | // static void struct_set(Handle<Struct>::type, int, Handle<Type>::type); |
| 283 | // template<class V> |
| 284 | // static i::Handle<V> struct_get_value(Handle<Struct>::type, int); |
| 285 | // template<class V> |
| 286 | // static void struct_set_value(Handle<Struct>::type, int, i::Handle<V>); |
| 287 | // } |
| 288 | template<class Config> |
| 289 | class TypeImpl : public Config::Base { |
| 290 | public: |
| 291 | // Auxiliary types. |
| 292 | |
| 293 | typedef uint32_t bitset; // Internal |
| 294 | class BitsetType; // Internal |
| 295 | class StructuralType; // Internal |
| 296 | class UnionType; // Internal |
| 297 | |
| 298 | class ClassType; |
| 299 | class ConstantType; |
| 300 | class RangeType; |
| 301 | class ContextType; |
| 302 | class ArrayType; |
| 303 | class FunctionType; |
| 304 | |
| 305 | typedef typename Config::template Handle<TypeImpl>::type TypeHandle; |
| 306 | typedef typename Config::template Handle<ClassType>::type ClassHandle; |
| 307 | typedef typename Config::template Handle<ConstantType>::type ConstantHandle; |
| 308 | typedef typename Config::template Handle<RangeType>::type RangeHandle; |
| 309 | typedef typename Config::template Handle<ContextType>::type ContextHandle; |
| 310 | typedef typename Config::template Handle<ArrayType>::type ArrayHandle; |
| 311 | typedef typename Config::template Handle<FunctionType>::type FunctionHandle; |
| 312 | typedef typename Config::template Handle<UnionType>::type UnionHandle; |
| 313 | typedef typename Config::Region Region; |
| 314 | |
| 315 | // Constructors. |
| 316 | |
| 317 | #define DEFINE_TYPE_CONSTRUCTOR(type, value) \ |
| 318 | static TypeImpl* type() { \ |
| 319 | return BitsetType::New(BitsetType::k##type); \ |
| 320 | } \ |
| 321 | static TypeHandle type(Region* region) { \ |
| 322 | return BitsetType::New(BitsetType::k##type, region); \ |
| 323 | } |
| 324 | PROPER_BITSET_TYPE_LIST(DEFINE_TYPE_CONSTRUCTOR) |
| 325 | #undef DEFINE_TYPE_CONSTRUCTOR |
| 326 | |
| 327 | static TypeHandle Class(i::Handle<i::Map> map, Region* region) { |
| 328 | return ClassType::New(map, region); |
| 329 | } |
| 330 | static TypeHandle Constant(i::Handle<i::Object> value, Region* region) { |
| 331 | return ConstantType::New(value, region); |
| 332 | } |
| 333 | static TypeHandle Range( |
| 334 | i::Handle<i::Object> min, i::Handle<i::Object> max, Region* region) { |
| 335 | return RangeType::New(min, max, region); |
| 336 | } |
| 337 | static TypeHandle Context(TypeHandle outer, Region* region) { |
| 338 | return ContextType::New(outer, region); |
| 339 | } |
| 340 | static TypeHandle Array(TypeHandle element, Region* region) { |
| 341 | return ArrayType::New(element, region); |
| 342 | } |
| 343 | static FunctionHandle Function( |
| 344 | TypeHandle result, TypeHandle receiver, int arity, Region* region) { |
| 345 | return FunctionType::New(result, receiver, arity, region); |
| 346 | } |
| 347 | static TypeHandle Function(TypeHandle result, Region* region) { |
| 348 | return Function(result, Any(region), 0, region); |
| 349 | } |
| 350 | static TypeHandle Function( |
| 351 | TypeHandle result, TypeHandle param0, Region* region) { |
| 352 | FunctionHandle function = Function(result, Any(region), 1, region); |
| 353 | function->InitParameter(0, param0); |
| 354 | return function; |
| 355 | } |
| 356 | static TypeHandle Function( |
| 357 | TypeHandle result, TypeHandle param0, TypeHandle param1, Region* region) { |
| 358 | FunctionHandle function = Function(result, Any(region), 2, region); |
| 359 | function->InitParameter(0, param0); |
| 360 | function->InitParameter(1, param1); |
| 361 | return function; |
| 362 | } |
| 363 | static TypeHandle Function( |
| 364 | TypeHandle result, TypeHandle param0, TypeHandle param1, |
| 365 | TypeHandle param2, Region* region) { |
| 366 | FunctionHandle function = Function(result, Any(region), 3, region); |
| 367 | function->InitParameter(0, param0); |
| 368 | function->InitParameter(1, param1); |
| 369 | function->InitParameter(2, param2); |
| 370 | return function; |
| 371 | } |
| 372 | |
| 373 | static TypeHandle Union(TypeHandle type1, TypeHandle type2, Region* reg); |
| 374 | static TypeHandle Intersect(TypeHandle type1, TypeHandle type2, Region* reg); |
| 375 | |
| 376 | static TypeHandle Of(double value, Region* region) { |
| 377 | return Config::from_bitset(BitsetType::Lub(value), region); |
| 378 | } |
| 379 | static TypeHandle Of(i::Object* value, Region* region) { |
| 380 | return Config::from_bitset(BitsetType::Lub(value), region); |
| 381 | } |
| 382 | static TypeHandle Of(i::Handle<i::Object> value, Region* region) { |
| 383 | return Of(*value, region); |
| 384 | } |
| 385 | |
| 386 | // Predicates. |
| 387 | |
| 388 | bool IsInhabited() { return BitsetType::IsInhabited(this->BitsetLub()); } |
| 389 | |
| 390 | bool Is(TypeImpl* that) { return this == that || this->SlowIs(that); } |
| 391 | template<class TypeHandle> |
| 392 | bool Is(TypeHandle that) { return this->Is(*that); } |
| 393 | |
| 394 | bool Maybe(TypeImpl* that); |
| 395 | template<class TypeHandle> |
| 396 | bool Maybe(TypeHandle that) { return this->Maybe(*that); } |
| 397 | |
| 398 | bool Equals(TypeImpl* that) { return this->Is(that) && that->Is(this); } |
| 399 | template<class TypeHandle> |
| 400 | bool Equals(TypeHandle that) { return this->Equals(*that); } |
| 401 | |
| 402 | // Equivalent to Constant(val)->Is(this), but avoiding allocation. |
| 403 | bool Contains(i::Object* val); |
| 404 | bool Contains(i::Handle<i::Object> val) { return this->Contains(*val); } |
| 405 | |
| 406 | // State-dependent versions of the above that consider subtyping between |
| 407 | // a constant and its map class. |
| 408 | inline static TypeHandle NowOf(i::Object* value, Region* region); |
| 409 | static TypeHandle NowOf(i::Handle<i::Object> value, Region* region) { |
| 410 | return NowOf(*value, region); |
| 411 | } |
| 412 | bool NowIs(TypeImpl* that); |
| 413 | template<class TypeHandle> |
| 414 | bool NowIs(TypeHandle that) { return this->NowIs(*that); } |
| 415 | inline bool NowContains(i::Object* val); |
| 416 | bool NowContains(i::Handle<i::Object> val) { return this->NowContains(*val); } |
| 417 | |
| 418 | bool NowStable(); |
| 419 | |
| 420 | // Inspection. |
| 421 | |
| 422 | bool IsClass() { |
| 423 | return Config::is_class(this) |
| 424 | || Config::is_struct(this, StructuralType::kClassTag); |
| 425 | } |
| 426 | bool IsConstant() { |
| 427 | return Config::is_struct(this, StructuralType::kConstantTag); |
| 428 | } |
| 429 | bool IsRange() { |
| 430 | return Config::is_struct(this, StructuralType::kRangeTag); |
| 431 | } |
| 432 | bool IsContext() { |
| 433 | return Config::is_struct(this, StructuralType::kContextTag); |
| 434 | } |
| 435 | bool IsArray() { |
| 436 | return Config::is_struct(this, StructuralType::kArrayTag); |
| 437 | } |
| 438 | bool IsFunction() { |
| 439 | return Config::is_struct(this, StructuralType::kFunctionTag); |
| 440 | } |
| 441 | |
| 442 | ClassType* AsClass() { return ClassType::cast(this); } |
| 443 | ConstantType* AsConstant() { return ConstantType::cast(this); } |
| 444 | RangeType* AsRange() { return RangeType::cast(this); } |
| 445 | ContextType* AsContext() { return ContextType::cast(this); } |
| 446 | ArrayType* AsArray() { return ArrayType::cast(this); } |
| 447 | FunctionType* AsFunction() { return FunctionType::cast(this); } |
| 448 | |
| 449 | // Minimum and maximum of a numeric type. |
| 450 | // These functions do not distinguish between -0 and +0. If the type equals |
| 451 | // kNaN, they return NaN; otherwise kNaN is ignored. Only call these |
| 452 | // functions on subtypes of Number. |
| 453 | double Min(); |
| 454 | double Max(); |
| 455 | |
| 456 | int NumClasses(); |
| 457 | int NumConstants(); |
| 458 | |
| 459 | template<class T> class Iterator; |
| 460 | Iterator<i::Map> Classes() { |
| 461 | if (this->IsBitset()) return Iterator<i::Map>(); |
| 462 | return Iterator<i::Map>(Config::handle(this)); |
| 463 | } |
| 464 | Iterator<i::Object> Constants() { |
| 465 | if (this->IsBitset()) return Iterator<i::Object>(); |
| 466 | return Iterator<i::Object>(Config::handle(this)); |
| 467 | } |
| 468 | |
| 469 | // Casting and conversion. |
| 470 | |
| 471 | static inline TypeImpl* cast(typename Config::Base* object); |
| 472 | |
| 473 | template<class OtherTypeImpl> |
| 474 | static TypeHandle Convert( |
| 475 | typename OtherTypeImpl::TypeHandle type, Region* region); |
| 476 | |
| 477 | // Printing. |
| 478 | |
| 479 | enum PrintDimension { BOTH_DIMS, SEMANTIC_DIM, REPRESENTATION_DIM }; |
| 480 | |
| 481 | void PrintTo(OStream& os, PrintDimension dim = BOTH_DIMS); // NOLINT |
| 482 | |
| 483 | #ifdef DEBUG |
| 484 | void Print(); |
| 485 | #endif |
| 486 | |
| 487 | protected: |
| 488 | // Friends. |
| 489 | |
| 490 | template<class> friend class Iterator; |
| 491 | template<class> friend class TypeImpl; |
| 492 | |
| 493 | // Handle conversion. |
| 494 | |
| 495 | template<class T> |
| 496 | static typename Config::template Handle<T>::type handle(T* type) { |
| 497 | return Config::handle(type); |
| 498 | } |
| 499 | TypeImpl* unhandle() { return this; } |
| 500 | |
| 501 | // Internal inspection. |
| 502 | |
| 503 | bool IsNone() { return this == None(); } |
| 504 | bool IsAny() { return this == Any(); } |
| 505 | bool IsBitset() { return Config::is_bitset(this); } |
| 506 | bool IsUnion() { return Config::is_struct(this, StructuralType::kUnionTag); } |
| 507 | |
| 508 | bitset AsBitset() { |
| 509 | DCHECK(this->IsBitset()); |
| 510 | return static_cast<BitsetType*>(this)->Bitset(); |
| 511 | } |
| 512 | UnionType* AsUnion() { return UnionType::cast(this); } |
| 513 | |
| 514 | // Auxiliary functions. |
| 515 | |
| 516 | bitset BitsetGlb() { return BitsetType::Glb(this); } |
| 517 | bitset BitsetLub() { return BitsetType::Lub(this); } |
| 518 | |
| 519 | bool SlowIs(TypeImpl* that); |
| 520 | |
| 521 | static bool IsInteger(double x) { |
| 522 | return nearbyint(x) == x && !i::IsMinusZero(x); // Allows for infinities. |
| 523 | } |
| 524 | static bool IsInteger(i::Object* x) { |
| 525 | return x->IsNumber() && IsInteger(x->Number()); |
| 526 | } |
| 527 | |
| 528 | struct Limits { |
| 529 | i::Handle<i::Object> min; |
| 530 | i::Handle<i::Object> max; |
| 531 | Limits(i::Handle<i::Object> min, i::Handle<i::Object> max) : |
| 532 | min(min), max(max) {} |
| 533 | explicit Limits(RangeType* range) : |
| 534 | min(range->Min()), max(range->Max()) {} |
| 535 | }; |
| 536 | |
| 537 | static Limits Intersect(Limits lhs, Limits rhs); |
| 538 | static Limits Union(Limits lhs, Limits rhs); |
| 539 | static bool Overlap(RangeType* lhs, RangeType* rhs); |
| 540 | static bool Contains(RangeType* lhs, RangeType* rhs); |
| 541 | static bool Contains(RangeType* range, i::Object* val); |
| 542 | |
| 543 | RangeType* GetRange(); |
| 544 | static int UpdateRange( |
| 545 | RangeHandle type, UnionHandle result, int size, Region* region); |
| 546 | |
| 547 | bool SimplyEquals(TypeImpl* that); |
| 548 | template<class TypeHandle> |
| 549 | bool SimplyEquals(TypeHandle that) { return this->SimplyEquals(*that); } |
| 550 | |
| 551 | static int AddToUnion( |
| 552 | TypeHandle type, UnionHandle result, int size, Region* region); |
| 553 | static int IntersectAux( |
| 554 | TypeHandle type, TypeHandle other, |
| 555 | UnionHandle result, int size, Region* region); |
| 556 | static TypeHandle NormalizeUnion(UnionHandle unioned, int size); |
| 557 | }; |
| 558 | |
| 559 | |
| 560 | // ----------------------------------------------------------------------------- |
| 561 | // Bitset types (internal). |
| 562 | |
| 563 | template<class Config> |
| 564 | class TypeImpl<Config>::BitsetType : public TypeImpl<Config> { |
| 565 | protected: |
| 566 | friend class TypeImpl<Config>; |
| 567 | |
| 568 | enum { |
| 569 | #define DECLARE_TYPE(type, value) k##type = (value), |
| 570 | BITSET_TYPE_LIST(DECLARE_TYPE) |
| 571 | #undef DECLARE_TYPE |
| 572 | kUnusedEOL = 0 |
| 573 | }; |
| 574 | |
| 575 | bitset Bitset() { return Config::as_bitset(this); } |
| 576 | |
| 577 | static TypeImpl* New(bitset bits) { |
| 578 | DCHECK(bits == kNone || IsInhabited(bits)); |
| 579 | return Config::from_bitset(bits); |
| 580 | } |
| 581 | static TypeHandle New(bitset bits, Region* region) { |
| 582 | DCHECK(bits == kNone || IsInhabited(bits)); |
| 583 | return Config::from_bitset(bits, region); |
| 584 | } |
| 585 | // TODO(neis): Eventually allow again for types with empty semantics |
| 586 | // part and modify intersection and possibly subtyping accordingly. |
| 587 | |
| 588 | static bool IsInhabited(bitset bits) { |
| 589 | return bits & kSemantic; |
| 590 | } |
| 591 | |
| 592 | static bool Is(bitset bits1, bitset bits2) { |
| 593 | return (bits1 | bits2) == bits2; |
| 594 | } |
| 595 | |
| 596 | static double Min(bitset); |
| 597 | static double Max(bitset); |
| 598 | |
| 599 | static bitset Glb(TypeImpl* type); // greatest lower bound that's a bitset |
| 600 | static bitset Lub(TypeImpl* type); // least upper bound that's a bitset |
| 601 | static bitset Lub(i::Object* value); |
| 602 | static bitset Lub(double value); |
| 603 | static bitset Lub(int32_t value); |
| 604 | static bitset Lub(uint32_t value); |
| 605 | static bitset Lub(i::Map* map); |
| 606 | static bitset Lub(Limits lim); |
| 607 | |
| 608 | static const char* Name(bitset); |
| 609 | static void Print(OStream& os, bitset); // NOLINT |
| 610 | #ifdef DEBUG |
| 611 | static void Print(bitset); |
| 612 | #endif |
| 613 | |
| 614 | private: |
| 615 | struct BitsetMin{ |
| 616 | bitset bits; |
| 617 | double min; |
| 618 | }; |
| 619 | static const BitsetMin BitsetMins31[]; |
| 620 | static const BitsetMin BitsetMins32[]; |
| 621 | static const BitsetMin* BitsetMins() { |
| 622 | return i::SmiValuesAre31Bits() ? BitsetMins31 : BitsetMins32; |
| 623 | } |
| 624 | static size_t BitsetMinsSize() { |
| 625 | return i::SmiValuesAre31Bits() ? 7 : 5; |
| 626 | /* arraysize(BitsetMins31) : arraysize(BitsetMins32); */ |
| 627 | // Using arraysize here doesn't compile on Windows. |
| 628 | } |
| 629 | }; |
| 630 | |
| 631 | |
| 632 | // ----------------------------------------------------------------------------- |
| 633 | // Superclass for non-bitset types (internal). |
| 634 | // Contains a tag and a variable number of type or value fields. |
| 635 | |
| 636 | template<class Config> |
| 637 | class TypeImpl<Config>::StructuralType : public TypeImpl<Config> { |
| 638 | protected: |
| 639 | template<class> friend class TypeImpl; |
| 640 | friend struct ZoneTypeConfig; // For tags. |
| 641 | friend struct HeapTypeConfig; |
| 642 | |
| 643 | enum Tag { |
| 644 | kClassTag, |
| 645 | kConstantTag, |
| 646 | kRangeTag, |
| 647 | kContextTag, |
| 648 | kArrayTag, |
| 649 | kFunctionTag, |
| 650 | kUnionTag |
| 651 | }; |
| 652 | |
| 653 | int Length() { |
| 654 | return Config::struct_length(Config::as_struct(this)); |
| 655 | } |
| 656 | TypeHandle Get(int i) { |
| 657 | DCHECK(0 <= i && i < this->Length()); |
| 658 | return Config::struct_get(Config::as_struct(this), i); |
| 659 | } |
| 660 | void Set(int i, TypeHandle type) { |
| 661 | DCHECK(0 <= i && i < this->Length()); |
| 662 | Config::struct_set(Config::as_struct(this), i, type); |
| 663 | } |
| 664 | void Shrink(int length) { |
| 665 | DCHECK(2 <= length && length <= this->Length()); |
| 666 | Config::struct_shrink(Config::as_struct(this), length); |
| 667 | } |
| 668 | template<class V> i::Handle<V> GetValue(int i) { |
| 669 | DCHECK(0 <= i && i < this->Length()); |
| 670 | return Config::template struct_get_value<V>(Config::as_struct(this), i); |
| 671 | } |
| 672 | template<class V> void SetValue(int i, i::Handle<V> x) { |
| 673 | DCHECK(0 <= i && i < this->Length()); |
| 674 | Config::struct_set_value(Config::as_struct(this), i, x); |
| 675 | } |
| 676 | |
| 677 | static TypeHandle New(Tag tag, int length, Region* region) { |
| 678 | DCHECK(1 <= length); |
| 679 | return Config::from_struct(Config::struct_create(tag, length, region)); |
| 680 | } |
| 681 | }; |
| 682 | |
| 683 | |
| 684 | // ----------------------------------------------------------------------------- |
| 685 | // Union types (internal). |
| 686 | // A union is a structured type with the following invariants: |
| 687 | // - its length is at least 2 |
| 688 | // - at most one field is a bitset, and it must go into index 0 |
| 689 | // - no field is a union |
| 690 | // - no field is a subtype of any other field |
| 691 | template<class Config> |
| 692 | class TypeImpl<Config>::UnionType : public StructuralType { |
| 693 | public: |
| 694 | static UnionHandle New(int length, Region* region) { |
| 695 | return Config::template cast<UnionType>( |
| 696 | StructuralType::New(StructuralType::kUnionTag, length, region)); |
| 697 | } |
| 698 | |
| 699 | static UnionType* cast(TypeImpl* type) { |
| 700 | DCHECK(type->IsUnion()); |
| 701 | return static_cast<UnionType*>(type); |
| 702 | } |
| 703 | |
| 704 | bool Wellformed(); |
| 705 | }; |
| 706 | |
| 707 | |
| 708 | // ----------------------------------------------------------------------------- |
| 709 | // Class types. |
| 710 | |
| 711 | template<class Config> |
| 712 | class TypeImpl<Config>::ClassType : public StructuralType { |
| 713 | public: |
| 714 | TypeHandle Bound(Region* region) { |
| 715 | return Config::is_class(this) ? |
| 716 | BitsetType::New(BitsetType::Lub(*Config::as_class(this)), region) : |
| 717 | this->Get(0); |
| 718 | } |
| 719 | i::Handle<i::Map> Map() { |
| 720 | return Config::is_class(this) ? Config::as_class(this) : |
| 721 | this->template GetValue<i::Map>(1); |
| 722 | } |
| 723 | |
| 724 | static ClassHandle New(i::Handle<i::Map> map, Region* region) { |
| 725 | ClassHandle type = |
| 726 | Config::template cast<ClassType>(Config::from_class(map, region)); |
| 727 | if (!type->IsClass()) { |
| 728 | type = Config::template cast<ClassType>( |
| 729 | StructuralType::New(StructuralType::kClassTag, 2, region)); |
| 730 | type->Set(0, BitsetType::New(BitsetType::Lub(*map), region)); |
| 731 | type->SetValue(1, map); |
| 732 | } |
| 733 | return type; |
| 734 | } |
| 735 | |
| 736 | static ClassType* cast(TypeImpl* type) { |
| 737 | DCHECK(type->IsClass()); |
| 738 | return static_cast<ClassType*>(type); |
| 739 | } |
| 740 | }; |
| 741 | |
| 742 | |
| 743 | // ----------------------------------------------------------------------------- |
| 744 | // Constant types. |
| 745 | |
| 746 | template<class Config> |
| 747 | class TypeImpl<Config>::ConstantType : public StructuralType { |
| 748 | public: |
| 749 | TypeHandle Bound() { return this->Get(0); } |
| 750 | i::Handle<i::Object> Value() { return this->template GetValue<i::Object>(1); } |
| 751 | |
| 752 | static ConstantHandle New(i::Handle<i::Object> value, Region* region) { |
| 753 | ConstantHandle type = Config::template cast<ConstantType>( |
| 754 | StructuralType::New(StructuralType::kConstantTag, 2, region)); |
| 755 | type->Set(0, BitsetType::New(BitsetType::Lub(*value), region)); |
| 756 | type->SetValue(1, value); |
| 757 | return type; |
| 758 | } |
| 759 | |
| 760 | static ConstantType* cast(TypeImpl* type) { |
| 761 | DCHECK(type->IsConstant()); |
| 762 | return static_cast<ConstantType*>(type); |
| 763 | } |
| 764 | }; |
| 765 | // TODO(neis): Also cache value if numerical. |
| 766 | // TODO(neis): Allow restricting the representation. |
| 767 | |
| 768 | |
| 769 | // ----------------------------------------------------------------------------- |
| 770 | // Range types. |
| 771 | |
| 772 | template<class Config> |
| 773 | class TypeImpl<Config>::RangeType : public StructuralType { |
| 774 | public: |
| 775 | int BitsetLub() { return this->Get(0)->AsBitset(); } |
| 776 | i::Handle<i::Object> Min() { return this->template GetValue<i::Object>(1); } |
| 777 | i::Handle<i::Object> Max() { return this->template GetValue<i::Object>(2); } |
| 778 | |
| 779 | static RangeHandle New( |
| 780 | i::Handle<i::Object> min, i::Handle<i::Object> max, Region* region) { |
| 781 | DCHECK(min->Number() <= max->Number()); |
| 782 | RangeHandle type = Config::template cast<RangeType>( |
| 783 | StructuralType::New(StructuralType::kRangeTag, 3, region)); |
| 784 | type->Set(0, BitsetType::New(BitsetType::Lub(Limits(min, max)), region)); |
| 785 | type->SetValue(1, min); |
| 786 | type->SetValue(2, max); |
| 787 | return type; |
| 788 | } |
| 789 | |
| 790 | static RangeHandle New(Limits lim, Region* region) { |
| 791 | return New(lim.min, lim.max, region); |
| 792 | } |
| 793 | |
| 794 | static RangeType* cast(TypeImpl* type) { |
| 795 | DCHECK(type->IsRange()); |
| 796 | return static_cast<RangeType*>(type); |
| 797 | } |
| 798 | }; |
| 799 | // TODO(neis): Also cache min and max values. |
| 800 | // TODO(neis): Allow restricting the representation. |
| 801 | |
| 802 | |
| 803 | // ----------------------------------------------------------------------------- |
| 804 | // Context types. |
| 805 | |
| 806 | template<class Config> |
| 807 | class TypeImpl<Config>::ContextType : public StructuralType { |
| 808 | public: |
| 809 | TypeHandle Outer() { return this->Get(0); } |
| 810 | |
| 811 | static ContextHandle New(TypeHandle outer, Region* region) { |
| 812 | ContextHandle type = Config::template cast<ContextType>( |
| 813 | StructuralType::New(StructuralType::kContextTag, 1, region)); |
| 814 | type->Set(0, outer); |
| 815 | return type; |
| 816 | } |
| 817 | |
| 818 | static ContextType* cast(TypeImpl* type) { |
| 819 | DCHECK(type->IsContext()); |
| 820 | return static_cast<ContextType*>(type); |
| 821 | } |
| 822 | }; |
| 823 | |
| 824 | |
| 825 | // ----------------------------------------------------------------------------- |
| 826 | // Array types. |
| 827 | |
| 828 | template<class Config> |
| 829 | class TypeImpl<Config>::ArrayType : public StructuralType { |
| 830 | public: |
| 831 | TypeHandle Element() { return this->Get(0); } |
| 832 | |
| 833 | static ArrayHandle New(TypeHandle element, Region* region) { |
| 834 | ArrayHandle type = Config::template cast<ArrayType>( |
| 835 | StructuralType::New(StructuralType::kArrayTag, 1, region)); |
| 836 | type->Set(0, element); |
| 837 | return type; |
| 838 | } |
| 839 | |
| 840 | static ArrayType* cast(TypeImpl* type) { |
| 841 | DCHECK(type->IsArray()); |
| 842 | return static_cast<ArrayType*>(type); |
| 843 | } |
| 844 | }; |
| 845 | |
| 846 | |
| 847 | // ----------------------------------------------------------------------------- |
| 848 | // Function types. |
| 849 | |
| 850 | template<class Config> |
| 851 | class TypeImpl<Config>::FunctionType : public StructuralType { |
| 852 | public: |
| 853 | int Arity() { return this->Length() - 2; } |
| 854 | TypeHandle Result() { return this->Get(0); } |
| 855 | TypeHandle Receiver() { return this->Get(1); } |
| 856 | TypeHandle Parameter(int i) { return this->Get(2 + i); } |
| 857 | |
| 858 | void InitParameter(int i, TypeHandle type) { this->Set(2 + i, type); } |
| 859 | |
| 860 | static FunctionHandle New( |
| 861 | TypeHandle result, TypeHandle receiver, int arity, Region* region) { |
| 862 | FunctionHandle type = Config::template cast<FunctionType>( |
| 863 | StructuralType::New(StructuralType::kFunctionTag, 2 + arity, region)); |
| 864 | type->Set(0, result); |
| 865 | type->Set(1, receiver); |
| 866 | return type; |
| 867 | } |
| 868 | |
| 869 | static FunctionType* cast(TypeImpl* type) { |
| 870 | DCHECK(type->IsFunction()); |
| 871 | return static_cast<FunctionType*>(type); |
| 872 | } |
| 873 | }; |
| 874 | |
| 875 | |
| 876 | // ----------------------------------------------------------------------------- |
| 877 | // Type iterators. |
| 878 | |
| 879 | template<class Config> template<class T> |
| 880 | class TypeImpl<Config>::Iterator { |
| 881 | public: |
| 882 | bool Done() const { return index_ < 0; } |
| 883 | i::Handle<T> Current(); |
| 884 | void Advance(); |
| 885 | |
| 886 | private: |
| 887 | template<class> friend class TypeImpl; |
| 888 | |
| 889 | Iterator() : index_(-1) {} |
| 890 | explicit Iterator(TypeHandle type) : type_(type), index_(-1) { |
| 891 | Advance(); |
| 892 | } |
| 893 | |
| 894 | inline bool matches(TypeHandle type); |
| 895 | inline TypeHandle get_type(); |
| 896 | |
| 897 | TypeHandle type_; |
| 898 | int index_; |
| 899 | }; |
| 900 | |
| 901 | |
| 902 | // ----------------------------------------------------------------------------- |
| 903 | // Zone-allocated types; they are either (odd) integers to represent bitsets, or |
| 904 | // (even) pointers to structures for everything else. |
| 905 | |
| 906 | struct ZoneTypeConfig { |
| 907 | typedef TypeImpl<ZoneTypeConfig> Type; |
| 908 | class Base {}; |
| 909 | typedef void* Struct; |
| 910 | typedef i::Zone Region; |
| 911 | template<class T> struct Handle { typedef T* type; }; |
| 912 | |
| 913 | template<class T> static inline T* handle(T* type); |
| 914 | template<class T> static inline T* cast(Type* type); |
| 915 | |
| 916 | static inline bool is_bitset(Type* type); |
| 917 | static inline bool is_class(Type* type); |
| 918 | static inline bool is_struct(Type* type, int tag); |
| 919 | |
| 920 | static inline Type::bitset as_bitset(Type* type); |
| 921 | static inline i::Handle<i::Map> as_class(Type* type); |
| 922 | static inline Struct* as_struct(Type* type); |
| 923 | |
| 924 | static inline Type* from_bitset(Type::bitset); |
| 925 | static inline Type* from_bitset(Type::bitset, Zone* zone); |
| 926 | static inline Type* from_class(i::Handle<i::Map> map, Zone* zone); |
| 927 | static inline Type* from_struct(Struct* structured); |
| 928 | |
| 929 | static inline Struct* struct_create(int tag, int length, Zone* zone); |
| 930 | static inline void struct_shrink(Struct* structure, int length); |
| 931 | static inline int struct_tag(Struct* structure); |
| 932 | static inline int struct_length(Struct* structure); |
| 933 | static inline Type* struct_get(Struct* structure, int i); |
| 934 | static inline void struct_set(Struct* structure, int i, Type* type); |
| 935 | template<class V> |
| 936 | static inline i::Handle<V> struct_get_value(Struct* structure, int i); |
| 937 | template<class V> static inline void struct_set_value( |
| 938 | Struct* structure, int i, i::Handle<V> x); |
| 939 | }; |
| 940 | |
| 941 | typedef TypeImpl<ZoneTypeConfig> Type; |
| 942 | |
| 943 | |
| 944 | // ----------------------------------------------------------------------------- |
| 945 | // Heap-allocated types; either smis for bitsets, maps for classes, boxes for |
| 946 | // constants, or fixed arrays for unions. |
| 947 | |
| 948 | struct HeapTypeConfig { |
| 949 | typedef TypeImpl<HeapTypeConfig> Type; |
| 950 | typedef i::Object Base; |
| 951 | typedef i::FixedArray Struct; |
| 952 | typedef i::Isolate Region; |
| 953 | template<class T> struct Handle { typedef i::Handle<T> type; }; |
| 954 | |
| 955 | template<class T> static inline i::Handle<T> handle(T* type); |
| 956 | template<class T> static inline i::Handle<T> cast(i::Handle<Type> type); |
| 957 | |
| 958 | static inline bool is_bitset(Type* type); |
| 959 | static inline bool is_class(Type* type); |
| 960 | static inline bool is_struct(Type* type, int tag); |
| 961 | |
| 962 | static inline Type::bitset as_bitset(Type* type); |
| 963 | static inline i::Handle<i::Map> as_class(Type* type); |
| 964 | static inline i::Handle<Struct> as_struct(Type* type); |
| 965 | |
| 966 | static inline Type* from_bitset(Type::bitset); |
| 967 | static inline i::Handle<Type> from_bitset(Type::bitset, Isolate* isolate); |
| 968 | static inline i::Handle<Type> from_class( |
| 969 | i::Handle<i::Map> map, Isolate* isolate); |
| 970 | static inline i::Handle<Type> from_struct(i::Handle<Struct> structure); |
| 971 | |
| 972 | static inline i::Handle<Struct> struct_create( |
| 973 | int tag, int length, Isolate* isolate); |
| 974 | static inline void struct_shrink(i::Handle<Struct> structure, int length); |
| 975 | static inline int struct_tag(i::Handle<Struct> structure); |
| 976 | static inline int struct_length(i::Handle<Struct> structure); |
| 977 | static inline i::Handle<Type> struct_get(i::Handle<Struct> structure, int i); |
| 978 | static inline void struct_set( |
| 979 | i::Handle<Struct> structure, int i, i::Handle<Type> type); |
| 980 | template<class V> |
| 981 | static inline i::Handle<V> struct_get_value( |
| 982 | i::Handle<Struct> structure, int i); |
| 983 | template<class V> |
| 984 | static inline void struct_set_value( |
| 985 | i::Handle<Struct> structure, int i, i::Handle<V> x); |
| 986 | }; |
| 987 | |
| 988 | typedef TypeImpl<HeapTypeConfig> HeapType; |
| 989 | |
| 990 | |
| 991 | // ----------------------------------------------------------------------------- |
| 992 | // Type bounds. A simple struct to represent a pair of lower/upper types. |
| 993 | |
| 994 | template<class Config> |
| 995 | struct BoundsImpl { |
| 996 | typedef TypeImpl<Config> Type; |
| 997 | typedef typename Type::TypeHandle TypeHandle; |
| 998 | typedef typename Type::Region Region; |
| 999 | |
| 1000 | TypeHandle lower; |
| 1001 | TypeHandle upper; |
| 1002 | |
| 1003 | BoundsImpl() {} |
| 1004 | explicit BoundsImpl(TypeHandle t) : lower(t), upper(t) {} |
| 1005 | BoundsImpl(TypeHandle l, TypeHandle u) : lower(l), upper(u) { |
| 1006 | DCHECK(lower->Is(upper)); |
| 1007 | } |
| 1008 | |
| 1009 | // Unrestricted bounds. |
| 1010 | static BoundsImpl Unbounded(Region* region) { |
| 1011 | return BoundsImpl(Type::None(region), Type::Any(region)); |
| 1012 | } |
| 1013 | |
| 1014 | // Meet: both b1 and b2 are known to hold. |
| 1015 | static BoundsImpl Both(BoundsImpl b1, BoundsImpl b2, Region* region) { |
| 1016 | TypeHandle lower = Type::Union(b1.lower, b2.lower, region); |
| 1017 | TypeHandle upper = Type::Intersect(b1.upper, b2.upper, region); |
| 1018 | // Lower bounds are considered approximate, correct as necessary. |
| 1019 | lower = Type::Intersect(lower, upper, region); |
| 1020 | return BoundsImpl(lower, upper); |
| 1021 | } |
| 1022 | |
| 1023 | // Join: either b1 or b2 is known to hold. |
| 1024 | static BoundsImpl Either(BoundsImpl b1, BoundsImpl b2, Region* region) { |
| 1025 | TypeHandle lower = Type::Intersect(b1.lower, b2.lower, region); |
| 1026 | TypeHandle upper = Type::Union(b1.upper, b2.upper, region); |
| 1027 | return BoundsImpl(lower, upper); |
| 1028 | } |
| 1029 | |
| 1030 | static BoundsImpl NarrowLower(BoundsImpl b, TypeHandle t, Region* region) { |
| 1031 | // Lower bounds are considered approximate, correct as necessary. |
| 1032 | t = Type::Intersect(t, b.upper, region); |
| 1033 | TypeHandle lower = Type::Union(b.lower, t, region); |
| 1034 | return BoundsImpl(lower, b.upper); |
| 1035 | } |
| 1036 | static BoundsImpl NarrowUpper(BoundsImpl b, TypeHandle t, Region* region) { |
| 1037 | TypeHandle lower = Type::Intersect(b.lower, t, region); |
| 1038 | TypeHandle upper = Type::Intersect(b.upper, t, region); |
| 1039 | return BoundsImpl(lower, upper); |
| 1040 | } |
| 1041 | |
| 1042 | bool Narrows(BoundsImpl that) { |
| 1043 | return that.lower->Is(this->lower) && this->upper->Is(that.upper); |
| 1044 | } |
| 1045 | }; |
| 1046 | |
| 1047 | typedef BoundsImpl<ZoneTypeConfig> Bounds; |
| 1048 | |
| 1049 | } } // namespace v8::internal |
| 1050 | |
| 1051 | #endif // V8_TYPES_H_ |