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_AST_AST_TYPES_H_ 6 #define V8_AST_AST_TYPES_H_ 7 8 #include "src/conversions.h" 9 #include "src/handles.h" 10 #include "src/objects.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 // OtherUndetectable < Object 46 // DetectableReceiver = Receiver - OtherUndetectable 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 may be an infinity, in which case that infinity 99 // itself is also included in the range. A range never contains NaN or -0. 100 // 101 // If a value v happens to be an integer n, then Constant(v) is considered a 102 // subtype of Range(n, n) (and therefore also a subtype of any larger range). 103 // In order to avoid large unions, however, it is usually a good idea to use 104 // Range rather than Constant. 105 // 106 // 107 // PREDICATES 108 // 109 // There are two main functions for testing types: 110 // 111 // T1->Is(T2) -- tests whether T1 is included in T2 (i.e., T1 <= T2) 112 // T1->Maybe(T2) -- tests whether T1 and T2 overlap (i.e., T1 /\ T2 =/= 0) 113 // 114 // Typically, the former is to be used to select representations (e.g., via 115 // T->Is(SignedSmall())), and the latter to check whether a specific case needs 116 // handling (e.g., via T->Maybe(Number())). 117 // 118 // There is no functionality to discover whether a type is a leaf in the 119 // lattice. That is intentional. It should always be possible to refine the 120 // lattice (e.g., splitting up number types further) without invalidating any 121 // existing assumptions or tests. 122 // Consequently, do not normally use Equals for type tests, always use Is! 123 // 124 // The NowIs operator implements state-sensitive subtying, as described above. 125 // Any compilation decision based on such temporary properties requires runtime 126 // guarding! 127 // 128 // 129 // PROPERTIES 130 // 131 // Various formal properties hold for constructors, operators, and predicates 132 // over types. For example, constructors are injective and subtyping is a 133 // complete partial order. 134 // 135 // See test/cctest/test-types.cc for a comprehensive executable specification, 136 // especially with respect to the properties of the more exotic 'temporal' 137 // constructors and predicates (those prefixed 'Now'). 138 // 139 // 140 // IMPLEMENTATION 141 // 142 // Internally, all 'primitive' types, and their unions, are represented as 143 // bitsets. Bit 0 is reserved for tagging. Class is a heap pointer to the 144 // respective map. Only structured types require allocation. 145 // Note that the bitset representation is closed under both Union and Intersect. 146 147 // ----------------------------------------------------------------------------- 148 // Values for bitset types 149 150 // clang-format off 151 152 #define AST_MASK_BITSET_TYPE_LIST(V) \ 153 V(Representation, 0xffc00000u) \ 154 V(Semantic, 0x003ffffeu) 155 156 #define AST_REPRESENTATION(k) ((k) & AstBitsetType::kRepresentation) 157 #define AST_SEMANTIC(k) ((k) & AstBitsetType::kSemantic) 158 159 // Bits 21-22 are available. 160 #define AST_REPRESENTATION_BITSET_TYPE_LIST(V) \ 161 V(None, 0) \ 162 V(UntaggedBit, 1u << 23 | kSemantic) \ 163 V(UntaggedIntegral8, 1u << 24 | kSemantic) \ 164 V(UntaggedIntegral16, 1u << 25 | kSemantic) \ 165 V(UntaggedIntegral32, 1u << 26 | kSemantic) \ 166 V(UntaggedFloat32, 1u << 27 | kSemantic) \ 167 V(UntaggedFloat64, 1u << 28 | kSemantic) \ 168 V(UntaggedPointer, 1u << 29 | kSemantic) \ 169 V(TaggedSigned, 1u << 30 | kSemantic) \ 170 V(TaggedPointer, 1u << 31 | kSemantic) \ 171 \ 172 V(UntaggedIntegral, kUntaggedBit | kUntaggedIntegral8 | \ 173 kUntaggedIntegral16 | kUntaggedIntegral32) \ 174 V(UntaggedFloat, kUntaggedFloat32 | kUntaggedFloat64) \ 175 V(UntaggedNumber, kUntaggedIntegral | kUntaggedFloat) \ 176 V(Untagged, kUntaggedNumber | kUntaggedPointer) \ 177 V(Tagged, kTaggedSigned | kTaggedPointer) 178 179 #define AST_INTERNAL_BITSET_TYPE_LIST(V) \ 180 V(OtherUnsigned31, 1u << 1 | AST_REPRESENTATION(kTagged | kUntaggedNumber)) \ 181 V(OtherUnsigned32, 1u << 2 | AST_REPRESENTATION(kTagged | kUntaggedNumber)) \ 182 V(OtherSigned32, 1u << 3 | AST_REPRESENTATION(kTagged | kUntaggedNumber)) \ 183 V(OtherNumber, 1u << 4 | AST_REPRESENTATION(kTagged | kUntaggedNumber)) 184 185 #define AST_SEMANTIC_BITSET_TYPE_LIST(V) \ 186 V(Negative31, 1u << 5 | \ 187 AST_REPRESENTATION(kTagged | kUntaggedNumber)) \ 188 V(Null, 1u << 6 | AST_REPRESENTATION(kTaggedPointer)) \ 189 V(Undefined, 1u << 7 | AST_REPRESENTATION(kTaggedPointer)) \ 190 V(Boolean, 1u << 8 | AST_REPRESENTATION(kTaggedPointer)) \ 191 V(Unsigned30, 1u << 9 | \ 192 AST_REPRESENTATION(kTagged | kUntaggedNumber)) \ 193 V(MinusZero, 1u << 10 | \ 194 AST_REPRESENTATION(kTagged | kUntaggedNumber)) \ 195 V(NaN, 1u << 11 | \ 196 AST_REPRESENTATION(kTagged | kUntaggedNumber)) \ 197 V(Symbol, 1u << 12 | AST_REPRESENTATION(kTaggedPointer)) \ 198 V(InternalizedString, 1u << 13 | AST_REPRESENTATION(kTaggedPointer)) \ 199 V(OtherString, 1u << 14 | AST_REPRESENTATION(kTaggedPointer)) \ 200 V(OtherObject, 1u << 15 | AST_REPRESENTATION(kTaggedPointer)) \ 201 V(OtherUndetectable, 1u << 16 | AST_REPRESENTATION(kTaggedPointer)) \ 202 V(Proxy, 1u << 17 | AST_REPRESENTATION(kTaggedPointer)) \ 203 V(Function, 1u << 18 | AST_REPRESENTATION(kTaggedPointer)) \ 204 V(Hole, 1u << 19 | AST_REPRESENTATION(kTaggedPointer)) \ 205 V(OtherInternal, 1u << 20 | \ 206 AST_REPRESENTATION(kTagged | kUntagged)) \ 207 \ 208 V(Signed31, kUnsigned30 | kNegative31) \ 209 V(Signed32, kSigned31 | kOtherUnsigned31 | \ 210 kOtherSigned32) \ 211 V(Signed32OrMinusZero, kSigned32 | kMinusZero) \ 212 V(Signed32OrMinusZeroOrNaN, kSigned32 | kMinusZero | kNaN) \ 213 V(Negative32, kNegative31 | kOtherSigned32) \ 214 V(Unsigned31, kUnsigned30 | kOtherUnsigned31) \ 215 V(Unsigned32, kUnsigned30 | kOtherUnsigned31 | \ 216 kOtherUnsigned32) \ 217 V(Unsigned32OrMinusZero, kUnsigned32 | kMinusZero) \ 218 V(Unsigned32OrMinusZeroOrNaN, kUnsigned32 | kMinusZero | kNaN) \ 219 V(Integral32, kSigned32 | kUnsigned32) \ 220 V(PlainNumber, kIntegral32 | kOtherNumber) \ 221 V(OrderedNumber, kPlainNumber | kMinusZero) \ 222 V(MinusZeroOrNaN, kMinusZero | kNaN) \ 223 V(Number, kOrderedNumber | kNaN) \ 224 V(String, kInternalizedString | kOtherString) \ 225 V(UniqueName, kSymbol | kInternalizedString) \ 226 V(Name, kSymbol | kString) \ 227 V(BooleanOrNumber, kBoolean | kNumber) \ 228 V(BooleanOrNullOrNumber, kBooleanOrNumber | kNull) \ 229 V(BooleanOrNullOrUndefined, kBoolean | kNull | kUndefined) \ 230 V(NullOrNumber, kNull | kNumber) \ 231 V(NullOrUndefined, kNull | kUndefined) \ 232 V(Undetectable, kNullOrUndefined | kOtherUndetectable) \ 233 V(NumberOrOddball, kNumber | kNullOrUndefined | kBoolean | kHole) \ 234 V(NumberOrString, kNumber | kString) \ 235 V(NumberOrUndefined, kNumber | kUndefined) \ 236 V(PlainPrimitive, kNumberOrString | kBoolean | kNullOrUndefined) \ 237 V(Primitive, kSymbol | kPlainPrimitive) \ 238 V(DetectableReceiver, kFunction | kOtherObject | kProxy) \ 239 V(Object, kFunction | kOtherObject | kOtherUndetectable) \ 240 V(Receiver, kObject | kProxy) \ 241 V(StringOrReceiver, kString | kReceiver) \ 242 V(Unique, kBoolean | kUniqueName | kNull | kUndefined | \ 243 kReceiver) \ 244 V(Internal, kHole | kOtherInternal) \ 245 V(NonInternal, kPrimitive | kReceiver) \ 246 V(NonNumber, kUnique | kString | kInternal) \ 247 V(Any, 0xfffffffeu) 248 249 // clang-format on 250 251 /* 252 * The following diagrams show how integers (in the mathematical sense) are 253 * divided among the different atomic numerical types. 254 * 255 * ON OS32 N31 U30 OU31 OU32 ON 256 * ______[_______[_______[_______[_______[_______[_______ 257 * -2^31 -2^30 0 2^30 2^31 2^32 258 * 259 * E.g., OtherUnsigned32 (OU32) covers all integers from 2^31 to 2^32-1. 260 * 261 * Some of the atomic numerical bitsets are internal only (see 262 * INTERNAL_BITSET_TYPE_LIST). To a types user, they should only occur in 263 * union with certain other bitsets. For instance, OtherNumber should only 264 * occur as part of PlainNumber. 265 */ 266 267 #define AST_PROPER_BITSET_TYPE_LIST(V) \ 268 AST_REPRESENTATION_BITSET_TYPE_LIST(V) \ 269 AST_SEMANTIC_BITSET_TYPE_LIST(V) 270 271 #define AST_BITSET_TYPE_LIST(V) \ 272 AST_MASK_BITSET_TYPE_LIST(V) \ 273 AST_REPRESENTATION_BITSET_TYPE_LIST(V) \ 274 AST_INTERNAL_BITSET_TYPE_LIST(V) \ 275 AST_SEMANTIC_BITSET_TYPE_LIST(V) 276 277 class AstType; 278 279 // ----------------------------------------------------------------------------- 280 // Bitset types (internal). 281 282 class AstBitsetType { 283 public: 284 typedef uint32_t bitset; // Internal 285 286 enum : uint32_t { 287 #define DECLARE_TYPE(type, value) k##type = (value), 288 AST_BITSET_TYPE_LIST(DECLARE_TYPE) 289 #undef DECLARE_TYPE 290 kUnusedEOL = 0 291 }; 292 293 static bitset SignedSmall(); 294 static bitset UnsignedSmall(); 295 296 bitset Bitset() { 297 return static_cast<bitset>(reinterpret_cast<uintptr_t>(this) ^ 1u); 298 } 299 300 static bool IsInhabited(bitset bits) { 301 return AST_SEMANTIC(bits) != kNone && AST_REPRESENTATION(bits) != kNone; 302 } 303 304 static bool SemanticIsInhabited(bitset bits) { 305 return AST_SEMANTIC(bits) != kNone; 306 } 307 308 static bool Is(bitset bits1, bitset bits2) { 309 return (bits1 | bits2) == bits2; 310 } 311 312 static double Min(bitset); 313 static double Max(bitset); 314 315 static bitset Glb(AstType* type); // greatest lower bound that's a bitset 316 static bitset Glb(double min, double max); 317 static bitset Lub(AstType* type); // least upper bound that's a bitset 318 static bitset Lub(i::Map* map); 319 static bitset Lub(i::Object* value); 320 static bitset Lub(double value); 321 static bitset Lub(double min, double max); 322 static bitset ExpandInternals(bitset bits); 323 324 static const char* Name(bitset); 325 static void Print(std::ostream& os, bitset); // NOLINT 326 #ifdef DEBUG 327 static void Print(bitset); 328 #endif 329 330 static bitset NumberBits(bitset bits); 331 332 static bool IsBitset(AstType* type) { 333 return reinterpret_cast<uintptr_t>(type) & 1; 334 } 335 336 static AstType* NewForTesting(bitset bits) { return New(bits); } 337 338 private: 339 friend class AstType; 340 341 static AstType* New(bitset bits) { 342 return reinterpret_cast<AstType*>(static_cast<uintptr_t>(bits | 1u)); 343 } 344 345 struct Boundary { 346 bitset internal; 347 bitset external; 348 double min; 349 }; 350 static const Boundary BoundariesArray[]; 351 static inline const Boundary* Boundaries(); 352 static inline size_t BoundariesSize(); 353 }; 354 355 // ----------------------------------------------------------------------------- 356 // Superclass for non-bitset types (internal). 357 class AstTypeBase { 358 protected: 359 friend class AstType; 360 361 enum Kind { 362 kClass, 363 kConstant, 364 kContext, 365 kArray, 366 kFunction, 367 kTuple, 368 kUnion, 369 kRange 370 }; 371 372 Kind kind() const { return kind_; } 373 explicit AstTypeBase(Kind kind) : kind_(kind) {} 374 375 static bool IsKind(AstType* type, Kind kind) { 376 if (AstBitsetType::IsBitset(type)) return false; 377 AstTypeBase* base = reinterpret_cast<AstTypeBase*>(type); 378 return base->kind() == kind; 379 } 380 381 // The hacky conversion to/from AstType*. 382 static AstType* AsType(AstTypeBase* type) { 383 return reinterpret_cast<AstType*>(type); 384 } 385 static AstTypeBase* FromType(AstType* type) { 386 return reinterpret_cast<AstTypeBase*>(type); 387 } 388 389 private: 390 Kind kind_; 391 }; 392 393 // ----------------------------------------------------------------------------- 394 // Class types. 395 396 class AstClassType : public AstTypeBase { 397 public: 398 i::Handle<i::Map> Map() { return map_; } 399 400 private: 401 friend class AstType; 402 friend class AstBitsetType; 403 404 static AstType* New(i::Handle<i::Map> map, Zone* zone) { 405 return AsType(new (zone->New(sizeof(AstClassType))) 406 AstClassType(AstBitsetType::Lub(*map), map)); 407 } 408 409 static AstClassType* cast(AstType* type) { 410 DCHECK(IsKind(type, kClass)); 411 return static_cast<AstClassType*>(FromType(type)); 412 } 413 414 AstClassType(AstBitsetType::bitset bitset, i::Handle<i::Map> map) 415 : AstTypeBase(kClass), bitset_(bitset), map_(map) {} 416 417 AstBitsetType::bitset Lub() { return bitset_; } 418 419 AstBitsetType::bitset bitset_; 420 Handle<i::Map> map_; 421 }; 422 423 // ----------------------------------------------------------------------------- 424 // Constant types. 425 426 class AstConstantType : public AstTypeBase { 427 public: 428 i::Handle<i::Object> Value() { return object_; } 429 430 private: 431 friend class AstType; 432 friend class AstBitsetType; 433 434 static AstType* New(i::Handle<i::Object> value, Zone* zone) { 435 AstBitsetType::bitset bitset = AstBitsetType::Lub(*value); 436 return AsType(new (zone->New(sizeof(AstConstantType))) 437 AstConstantType(bitset, value)); 438 } 439 440 static AstConstantType* cast(AstType* type) { 441 DCHECK(IsKind(type, kConstant)); 442 return static_cast<AstConstantType*>(FromType(type)); 443 } 444 445 AstConstantType(AstBitsetType::bitset bitset, i::Handle<i::Object> object) 446 : AstTypeBase(kConstant), bitset_(bitset), object_(object) {} 447 448 AstBitsetType::bitset Lub() { return bitset_; } 449 450 AstBitsetType::bitset bitset_; 451 Handle<i::Object> object_; 452 }; 453 // TODO(neis): Also cache value if numerical. 454 // TODO(neis): Allow restricting the representation. 455 456 // ----------------------------------------------------------------------------- 457 // Range types. 458 459 class AstRangeType : public AstTypeBase { 460 public: 461 struct Limits { 462 double min; 463 double max; 464 Limits(double min, double max) : min(min), max(max) {} 465 explicit Limits(AstRangeType* range) 466 : min(range->Min()), max(range->Max()) {} 467 bool IsEmpty(); 468 static Limits Empty() { return Limits(1, 0); } 469 static Limits Intersect(Limits lhs, Limits rhs); 470 static Limits Union(Limits lhs, Limits rhs); 471 }; 472 473 double Min() { return limits_.min; } 474 double Max() { return limits_.max; } 475 476 private: 477 friend class AstType; 478 friend class AstBitsetType; 479 friend class AstUnionType; 480 481 static AstType* New(double min, double max, 482 AstBitsetType::bitset representation, Zone* zone) { 483 return New(Limits(min, max), representation, zone); 484 } 485 486 static bool IsInteger(double x) { 487 return nearbyint(x) == x && !i::IsMinusZero(x); // Allows for infinities. 488 } 489 490 static AstType* New(Limits lim, AstBitsetType::bitset representation, 491 Zone* zone) { 492 DCHECK(IsInteger(lim.min) && IsInteger(lim.max)); 493 DCHECK(lim.min <= lim.max); 494 DCHECK(AST_REPRESENTATION(representation) == representation); 495 AstBitsetType::bitset bits = 496 AST_SEMANTIC(AstBitsetType::Lub(lim.min, lim.max)) | representation; 497 498 return AsType(new (zone->New(sizeof(AstRangeType))) 499 AstRangeType(bits, lim)); 500 } 501 502 static AstRangeType* cast(AstType* type) { 503 DCHECK(IsKind(type, kRange)); 504 return static_cast<AstRangeType*>(FromType(type)); 505 } 506 507 AstRangeType(AstBitsetType::bitset bitset, Limits limits) 508 : AstTypeBase(kRange), bitset_(bitset), limits_(limits) {} 509 510 AstBitsetType::bitset Lub() { return bitset_; } 511 512 AstBitsetType::bitset bitset_; 513 Limits limits_; 514 }; 515 516 // ----------------------------------------------------------------------------- 517 // Context types. 518 519 class AstContextType : public AstTypeBase { 520 public: 521 AstType* Outer() { return outer_; } 522 523 private: 524 friend class AstType; 525 526 static AstType* New(AstType* outer, Zone* zone) { 527 return AsType(new (zone->New(sizeof(AstContextType))) 528 AstContextType(outer)); // NOLINT 529 } 530 531 static AstContextType* cast(AstType* type) { 532 DCHECK(IsKind(type, kContext)); 533 return static_cast<AstContextType*>(FromType(type)); 534 } 535 536 explicit AstContextType(AstType* outer) 537 : AstTypeBase(kContext), outer_(outer) {} 538 539 AstType* outer_; 540 }; 541 542 // ----------------------------------------------------------------------------- 543 // Array types. 544 545 class AstArrayType : public AstTypeBase { 546 public: 547 AstType* Element() { return element_; } 548 549 private: 550 friend class AstType; 551 552 explicit AstArrayType(AstType* element) 553 : AstTypeBase(kArray), element_(element) {} 554 555 static AstType* New(AstType* element, Zone* zone) { 556 return AsType(new (zone->New(sizeof(AstArrayType))) AstArrayType(element)); 557 } 558 559 static AstArrayType* cast(AstType* type) { 560 DCHECK(IsKind(type, kArray)); 561 return static_cast<AstArrayType*>(FromType(type)); 562 } 563 564 AstType* element_; 565 }; 566 567 // ----------------------------------------------------------------------------- 568 // Superclass for types with variable number of type fields. 569 class AstStructuralType : public AstTypeBase { 570 public: 571 int LengthForTesting() { return Length(); } 572 573 protected: 574 friend class AstType; 575 576 int Length() { return length_; } 577 578 AstType* Get(int i) { 579 DCHECK(0 <= i && i < this->Length()); 580 return elements_[i]; 581 } 582 583 void Set(int i, AstType* type) { 584 DCHECK(0 <= i && i < this->Length()); 585 elements_[i] = type; 586 } 587 588 void Shrink(int length) { 589 DCHECK(2 <= length && length <= this->Length()); 590 length_ = length; 591 } 592 593 AstStructuralType(Kind kind, int length, i::Zone* zone) 594 : AstTypeBase(kind), length_(length) { 595 elements_ = 596 reinterpret_cast<AstType**>(zone->New(sizeof(AstType*) * length)); 597 } 598 599 private: 600 int length_; 601 AstType** elements_; 602 }; 603 604 // ----------------------------------------------------------------------------- 605 // Function types. 606 607 class AstFunctionType : public AstStructuralType { 608 public: 609 int Arity() { return this->Length() - 2; } 610 AstType* Result() { return this->Get(0); } 611 AstType* Receiver() { return this->Get(1); } 612 AstType* Parameter(int i) { return this->Get(2 + i); } 613 614 void InitParameter(int i, AstType* type) { this->Set(2 + i, type); } 615 616 private: 617 friend class AstType; 618 619 AstFunctionType(AstType* result, AstType* receiver, int arity, Zone* zone) 620 : AstStructuralType(kFunction, 2 + arity, zone) { 621 Set(0, result); 622 Set(1, receiver); 623 } 624 625 static AstType* New(AstType* result, AstType* receiver, int arity, 626 Zone* zone) { 627 return AsType(new (zone->New(sizeof(AstFunctionType))) 628 AstFunctionType(result, receiver, arity, zone)); 629 } 630 631 static AstFunctionType* cast(AstType* type) { 632 DCHECK(IsKind(type, kFunction)); 633 return static_cast<AstFunctionType*>(FromType(type)); 634 } 635 }; 636 637 // ----------------------------------------------------------------------------- 638 // Tuple types. 639 640 class AstTupleType : public AstStructuralType { 641 public: 642 int Arity() { return this->Length(); } 643 AstType* Element(int i) { return this->Get(i); } 644 645 void InitElement(int i, AstType* type) { this->Set(i, type); } 646 647 private: 648 friend class AstType; 649 650 AstTupleType(int length, Zone* zone) 651 : AstStructuralType(kTuple, length, zone) {} 652 653 static AstType* New(int length, Zone* zone) { 654 return AsType(new (zone->New(sizeof(AstTupleType))) 655 AstTupleType(length, zone)); 656 } 657 658 static AstTupleType* cast(AstType* type) { 659 DCHECK(IsKind(type, kTuple)); 660 return static_cast<AstTupleType*>(FromType(type)); 661 } 662 }; 663 664 // ----------------------------------------------------------------------------- 665 // Union types (internal). 666 // A union is a structured type with the following invariants: 667 // - its length is at least 2 668 // - at most one field is a bitset, and it must go into index 0 669 // - no field is a union 670 // - no field is a subtype of any other field 671 class AstUnionType : public AstStructuralType { 672 private: 673 friend AstType; 674 friend AstBitsetType; 675 676 AstUnionType(int length, Zone* zone) 677 : AstStructuralType(kUnion, length, zone) {} 678 679 static AstType* New(int length, Zone* zone) { 680 return AsType(new (zone->New(sizeof(AstUnionType))) 681 AstUnionType(length, zone)); 682 } 683 684 static AstUnionType* cast(AstType* type) { 685 DCHECK(IsKind(type, kUnion)); 686 return static_cast<AstUnionType*>(FromType(type)); 687 } 688 689 bool Wellformed(); 690 }; 691 692 class AstType { 693 public: 694 typedef AstBitsetType::bitset bitset; // Internal 695 696 // Constructors. 697 #define DEFINE_TYPE_CONSTRUCTOR(type, value) \ 698 static AstType* type() { return AstBitsetType::New(AstBitsetType::k##type); } 699 AST_PROPER_BITSET_TYPE_LIST(DEFINE_TYPE_CONSTRUCTOR) 700 #undef DEFINE_TYPE_CONSTRUCTOR 701 702 static AstType* SignedSmall() { 703 return AstBitsetType::New(AstBitsetType::SignedSmall()); 704 } 705 static AstType* UnsignedSmall() { 706 return AstBitsetType::New(AstBitsetType::UnsignedSmall()); 707 } 708 709 static AstType* Class(i::Handle<i::Map> map, Zone* zone) { 710 return AstClassType::New(map, zone); 711 } 712 static AstType* Constant(i::Handle<i::Object> value, Zone* zone) { 713 return AstConstantType::New(value, zone); 714 } 715 static AstType* Range(double min, double max, Zone* zone) { 716 return AstRangeType::New(min, max, 717 AST_REPRESENTATION(AstBitsetType::kTagged | 718 AstBitsetType::kUntaggedNumber), 719 zone); 720 } 721 static AstType* Context(AstType* outer, Zone* zone) { 722 return AstContextType::New(outer, zone); 723 } 724 static AstType* Array(AstType* element, Zone* zone) { 725 return AstArrayType::New(element, zone); 726 } 727 static AstType* Function(AstType* result, AstType* receiver, int arity, 728 Zone* zone) { 729 return AstFunctionType::New(result, receiver, arity, zone); 730 } 731 static AstType* Function(AstType* result, Zone* zone) { 732 return Function(result, Any(), 0, zone); 733 } 734 static AstType* Function(AstType* result, AstType* param0, Zone* zone) { 735 AstType* function = Function(result, Any(), 1, zone); 736 function->AsFunction()->InitParameter(0, param0); 737 return function; 738 } 739 static AstType* Function(AstType* result, AstType* param0, AstType* param1, 740 Zone* zone) { 741 AstType* function = Function(result, Any(), 2, zone); 742 function->AsFunction()->InitParameter(0, param0); 743 function->AsFunction()->InitParameter(1, param1); 744 return function; 745 } 746 static AstType* Function(AstType* result, AstType* param0, AstType* param1, 747 AstType* param2, Zone* zone) { 748 AstType* function = Function(result, Any(), 3, zone); 749 function->AsFunction()->InitParameter(0, param0); 750 function->AsFunction()->InitParameter(1, param1); 751 function->AsFunction()->InitParameter(2, param2); 752 return function; 753 } 754 static AstType* Function(AstType* result, int arity, AstType** params, 755 Zone* zone) { 756 AstType* function = Function(result, Any(), arity, zone); 757 for (int i = 0; i < arity; ++i) { 758 function->AsFunction()->InitParameter(i, params[i]); 759 } 760 return function; 761 } 762 static AstType* Tuple(AstType* first, AstType* second, AstType* third, 763 Zone* zone) { 764 AstType* tuple = AstTupleType::New(3, zone); 765 tuple->AsTuple()->InitElement(0, first); 766 tuple->AsTuple()->InitElement(1, second); 767 tuple->AsTuple()->InitElement(2, third); 768 return tuple; 769 } 770 771 static AstType* Union(AstType* type1, AstType* type2, Zone* zone); 772 static AstType* Intersect(AstType* type1, AstType* type2, Zone* zone); 773 774 static AstType* Of(double value, Zone* zone) { 775 return AstBitsetType::New( 776 AstBitsetType::ExpandInternals(AstBitsetType::Lub(value))); 777 } 778 static AstType* Of(i::Object* value, Zone* zone) { 779 return AstBitsetType::New( 780 AstBitsetType::ExpandInternals(AstBitsetType::Lub(value))); 781 } 782 static AstType* Of(i::Handle<i::Object> value, Zone* zone) { 783 return Of(*value, zone); 784 } 785 786 static AstType* For(i::Map* map) { 787 return AstBitsetType::New( 788 AstBitsetType::ExpandInternals(AstBitsetType::Lub(map))); 789 } 790 static AstType* For(i::Handle<i::Map> map) { return For(*map); } 791 792 // Extraction of components. 793 static AstType* Representation(AstType* t, Zone* zone); 794 static AstType* Semantic(AstType* t, Zone* zone); 795 796 // Predicates. 797 bool IsInhabited() { return AstBitsetType::IsInhabited(this->BitsetLub()); } 798 799 bool Is(AstType* that) { return this == that || this->SlowIs(that); } 800 bool Maybe(AstType* that); 801 bool Equals(AstType* that) { return this->Is(that) && that->Is(this); } 802 803 // Equivalent to Constant(val)->Is(this), but avoiding allocation. 804 bool Contains(i::Object* val); 805 bool Contains(i::Handle<i::Object> val) { return this->Contains(*val); } 806 807 // State-dependent versions of the above that consider subtyping between 808 // a constant and its map class. 809 static AstType* NowOf(i::Object* value, Zone* zone); 810 static AstType* NowOf(i::Handle<i::Object> value, Zone* zone) { 811 return NowOf(*value, zone); 812 } 813 bool NowIs(AstType* that); 814 bool NowContains(i::Object* val); 815 bool NowContains(i::Handle<i::Object> val) { return this->NowContains(*val); } 816 817 bool NowStable(); 818 819 // Inspection. 820 bool IsRange() { return IsKind(AstTypeBase::kRange); } 821 bool IsClass() { return IsKind(AstTypeBase::kClass); } 822 bool IsConstant() { return IsKind(AstTypeBase::kConstant); } 823 bool IsContext() { return IsKind(AstTypeBase::kContext); } 824 bool IsArray() { return IsKind(AstTypeBase::kArray); } 825 bool IsFunction() { return IsKind(AstTypeBase::kFunction); } 826 bool IsTuple() { return IsKind(AstTypeBase::kTuple); } 827 828 AstClassType* AsClass() { return AstClassType::cast(this); } 829 AstConstantType* AsConstant() { return AstConstantType::cast(this); } 830 AstRangeType* AsRange() { return AstRangeType::cast(this); } 831 AstContextType* AsContext() { return AstContextType::cast(this); } 832 AstArrayType* AsArray() { return AstArrayType::cast(this); } 833 AstFunctionType* AsFunction() { return AstFunctionType::cast(this); } 834 AstTupleType* AsTuple() { return AstTupleType::cast(this); } 835 836 // Minimum and maximum of a numeric type. 837 // These functions do not distinguish between -0 and +0. If the type equals 838 // kNaN, they return NaN; otherwise kNaN is ignored. Only call these 839 // functions on subtypes of Number. 840 double Min(); 841 double Max(); 842 843 // Extracts a range from the type: if the type is a range or a union 844 // containing a range, that range is returned; otherwise, NULL is returned. 845 AstType* GetRange(); 846 847 static bool IsInteger(i::Object* x); 848 static bool IsInteger(double x) { 849 return nearbyint(x) == x && !i::IsMinusZero(x); // Allows for infinities. 850 } 851 852 int NumClasses(); 853 int NumConstants(); 854 855 template <class T> 856 class Iterator { 857 public: 858 bool Done() const { return index_ < 0; } 859 i::Handle<T> Current(); 860 void Advance(); 861 862 private: 863 friend class AstType; 864 865 Iterator() : index_(-1) {} 866 explicit Iterator(AstType* type) : type_(type), index_(-1) { Advance(); } 867 868 inline bool matches(AstType* type); 869 inline AstType* get_type(); 870 871 AstType* type_; 872 int index_; 873 }; 874 875 Iterator<i::Map> Classes() { 876 if (this->IsBitset()) return Iterator<i::Map>(); 877 return Iterator<i::Map>(this); 878 } 879 Iterator<i::Object> Constants() { 880 if (this->IsBitset()) return Iterator<i::Object>(); 881 return Iterator<i::Object>(this); 882 } 883 884 // Printing. 885 886 enum PrintDimension { BOTH_DIMS, SEMANTIC_DIM, REPRESENTATION_DIM }; 887 888 void PrintTo(std::ostream& os, PrintDimension dim = BOTH_DIMS); // NOLINT 889 890 #ifdef DEBUG 891 void Print(); 892 #endif 893 894 // Helpers for testing. 895 bool IsBitsetForTesting() { return IsBitset(); } 896 bool IsUnionForTesting() { return IsUnion(); } 897 bitset AsBitsetForTesting() { return AsBitset(); } 898 AstUnionType* AsUnionForTesting() { return AsUnion(); } 899 900 private: 901 // Friends. 902 template <class> 903 friend class Iterator; 904 friend AstBitsetType; 905 friend AstUnionType; 906 907 // Internal inspection. 908 bool IsKind(AstTypeBase::Kind kind) { 909 return AstTypeBase::IsKind(this, kind); 910 } 911 912 bool IsNone() { return this == None(); } 913 bool IsAny() { return this == Any(); } 914 bool IsBitset() { return AstBitsetType::IsBitset(this); } 915 bool IsUnion() { return IsKind(AstTypeBase::kUnion); } 916 917 bitset AsBitset() { 918 DCHECK(this->IsBitset()); 919 return reinterpret_cast<AstBitsetType*>(this)->Bitset(); 920 } 921 AstUnionType* AsUnion() { return AstUnionType::cast(this); } 922 923 bitset Representation(); 924 925 // Auxiliary functions. 926 bool SemanticMaybe(AstType* that); 927 928 bitset BitsetGlb() { return AstBitsetType::Glb(this); } 929 bitset BitsetLub() { return AstBitsetType::Lub(this); } 930 931 bool SlowIs(AstType* that); 932 bool SemanticIs(AstType* that); 933 934 static bool Overlap(AstRangeType* lhs, AstRangeType* rhs); 935 static bool Contains(AstRangeType* lhs, AstRangeType* rhs); 936 static bool Contains(AstRangeType* range, AstConstantType* constant); 937 static bool Contains(AstRangeType* range, i::Object* val); 938 939 static int UpdateRange(AstType* type, AstUnionType* result, int size, 940 Zone* zone); 941 942 static AstRangeType::Limits IntersectRangeAndBitset(AstType* range, 943 AstType* bits, 944 Zone* zone); 945 static AstRangeType::Limits ToLimits(bitset bits, Zone* zone); 946 947 bool SimplyEquals(AstType* that); 948 949 static int AddToUnion(AstType* type, AstUnionType* result, int size, 950 Zone* zone); 951 static int IntersectAux(AstType* type, AstType* other, AstUnionType* result, 952 int size, AstRangeType::Limits* limits, Zone* zone); 953 static AstType* NormalizeUnion(AstType* unioned, int size, Zone* zone); 954 static AstType* NormalizeRangeAndBitset(AstType* range, bitset* bits, 955 Zone* zone); 956 }; 957 958 // ----------------------------------------------------------------------------- 959 // Type bounds. A simple struct to represent a pair of lower/upper types. 960 961 struct AstBounds { 962 AstType* lower; 963 AstType* upper; 964 965 AstBounds() 966 : // Make sure accessing uninitialized bounds crashes big-time. 967 lower(nullptr), 968 upper(nullptr) {} 969 explicit AstBounds(AstType* t) : lower(t), upper(t) {} 970 AstBounds(AstType* l, AstType* u) : lower(l), upper(u) { 971 DCHECK(lower->Is(upper)); 972 } 973 974 // Unrestricted bounds. 975 static AstBounds Unbounded() { 976 return AstBounds(AstType::None(), AstType::Any()); 977 } 978 979 // Meet: both b1 and b2 are known to hold. 980 static AstBounds Both(AstBounds b1, AstBounds b2, Zone* zone) { 981 AstType* lower = AstType::Union(b1.lower, b2.lower, zone); 982 AstType* upper = AstType::Intersect(b1.upper, b2.upper, zone); 983 // Lower bounds are considered approximate, correct as necessary. 984 if (!lower->Is(upper)) lower = upper; 985 return AstBounds(lower, upper); 986 } 987 988 // Join: either b1 or b2 is known to hold. 989 static AstBounds Either(AstBounds b1, AstBounds b2, Zone* zone) { 990 AstType* lower = AstType::Intersect(b1.lower, b2.lower, zone); 991 AstType* upper = AstType::Union(b1.upper, b2.upper, zone); 992 return AstBounds(lower, upper); 993 } 994 995 static AstBounds NarrowLower(AstBounds b, AstType* t, Zone* zone) { 996 AstType* lower = AstType::Union(b.lower, t, zone); 997 // Lower bounds are considered approximate, correct as necessary. 998 if (!lower->Is(b.upper)) lower = b.upper; 999 return AstBounds(lower, b.upper); 1000 } 1001 static AstBounds NarrowUpper(AstBounds b, AstType* t, Zone* zone) { 1002 AstType* lower = b.lower; 1003 AstType* upper = AstType::Intersect(b.upper, t, zone); 1004 // Lower bounds are considered approximate, correct as necessary. 1005 if (!lower->Is(upper)) lower = upper; 1006 return AstBounds(lower, upper); 1007 } 1008 1009 bool Narrows(AstBounds that) { 1010 return that.lower->Is(this->lower) && this->upper->Is(that.upper); 1011 } 1012 }; 1013 1014 } // namespace internal 1015 } // namespace v8 1016 1017 #endif // V8_AST_AST_TYPES_H_ 1018
