PointerUnion.h revision 586ea17be9fbf2fa1f2341900ebf1675a0924edc
1//===- llvm/ADT/PointerUnion.h - Discriminated Union of 2 Ptrs --*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file defines the PointerUnion class, which is a discriminated union of 11// pointer types. 12// 13//===----------------------------------------------------------------------===// 14 15#ifndef LLVM_ADT_POINTERUNION_H 16#define LLVM_ADT_POINTERUNION_H 17 18#include "llvm/Support/Compiler.h" 19#include "llvm/ADT/PointerIntPair.h" 20 21namespace llvm { 22 23 template <typename T> 24 struct PointerUnionTypeSelectorReturn { 25 typedef T Return; 26 }; 27 28 /// \brief Get a type based on whether two types are the same or not. For: 29 /// @code 30 /// typedef typename PointerUnionTypeSelector<T1, T2, EQ, NE>::Return Ret; 31 /// @endcode 32 /// Ret will be EQ type if T1 is same as T2 or NE type otherwise. 33 template <typename T1, typename T2, typename RET_EQ, typename RET_NE> 34 struct PointerUnionTypeSelector { 35 typedef typename PointerUnionTypeSelectorReturn<RET_NE>::Return Return; 36 }; 37 38 template <typename T, typename RET_EQ, typename RET_NE> 39 struct PointerUnionTypeSelector<T, T, RET_EQ, RET_NE> { 40 typedef typename PointerUnionTypeSelectorReturn<RET_EQ>::Return Return; 41 }; 42 43 template <typename T1, typename T2, typename RET_EQ, typename RET_NE> 44 struct PointerUnionTypeSelectorReturn< 45 PointerUnionTypeSelector<T1, T2, RET_EQ, RET_NE> > { 46 typedef typename PointerUnionTypeSelector<T1, T2, RET_EQ, RET_NE>::Return 47 Return; 48 }; 49 50 /// Provide PointerLikeTypeTraits for void* that is used by PointerUnion 51 /// for the two template arguments. 52 template <typename PT1, typename PT2> 53 class PointerUnionUIntTraits { 54 public: 55 static inline void *getAsVoidPointer(void *P) { return P; } 56 static inline void *getFromVoidPointer(void *P) { return P; } 57 enum { 58 PT1BitsAv = (int)(PointerLikeTypeTraits<PT1>::NumLowBitsAvailable), 59 PT2BitsAv = (int)(PointerLikeTypeTraits<PT2>::NumLowBitsAvailable), 60 NumLowBitsAvailable = PT1BitsAv < PT2BitsAv ? PT1BitsAv : PT2BitsAv 61 }; 62 }; 63 64 /// PointerUnion - This implements a discriminated union of two pointer types, 65 /// and keeps the discriminator bit-mangled into the low bits of the pointer. 66 /// This allows the implementation to be extremely efficient in space, but 67 /// permits a very natural and type-safe API. 68 /// 69 /// Common use patterns would be something like this: 70 /// PointerUnion<int*, float*> P; 71 /// P = (int*)0; 72 /// printf("%d %d", P.is<int*>(), P.is<float*>()); // prints "1 0" 73 /// X = P.get<int*>(); // ok. 74 /// Y = P.get<float*>(); // runtime assertion failure. 75 /// Z = P.get<double*>(); // runtime assertion failure (regardless of tag) 76 /// P = (float*)0; 77 /// Y = P.get<float*>(); // ok. 78 /// X = P.get<int*>(); // runtime assertion failure. 79 template <typename PT1, typename PT2> 80 class PointerUnion { 81 public: 82 typedef PointerIntPair<void*, 1, bool, 83 PointerUnionUIntTraits<PT1,PT2> > ValTy; 84 private: 85 ValTy Val; 86 87 struct IsPT1 { 88 static const int Num = 0; 89 }; 90 struct IsPT2 { 91 static const int Num = 1; 92 }; 93 template <typename T> 94 struct UNION_DOESNT_CONTAIN_TYPE { }; 95 96 public: 97 PointerUnion() {} 98 99 PointerUnion(PT1 V) : Val( 100 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(V))) { 101 } 102 PointerUnion(PT2 V) : Val( 103 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(V)), 1) { 104 } 105 106 /// isNull - Return true if the pointer held in the union is null, 107 /// regardless of which type it is. 108 bool isNull() const { 109 // Convert from the void* to one of the pointer types, to make sure that 110 // we recursively strip off low bits if we have a nested PointerUnion. 111 return !PointerLikeTypeTraits<PT1>::getFromVoidPointer(Val.getPointer()); 112 } 113 LLVM_EXPLICIT operator bool() const { return !isNull(); } 114 115 /// is<T>() return true if the Union currently holds the type matching T. 116 template<typename T> 117 int is() const { 118 typedef typename 119 ::llvm::PointerUnionTypeSelector<PT1, T, IsPT1, 120 ::llvm::PointerUnionTypeSelector<PT2, T, IsPT2, 121 UNION_DOESNT_CONTAIN_TYPE<T> > >::Return Ty; 122 int TyNo = Ty::Num; 123 return static_cast<int>(Val.getInt()) == TyNo; 124 } 125 126 /// get<T>() - Return the value of the specified pointer type. If the 127 /// specified pointer type is incorrect, assert. 128 template<typename T> 129 T get() const { 130 assert(is<T>() && "Invalid accessor called"); 131 return PointerLikeTypeTraits<T>::getFromVoidPointer(Val.getPointer()); 132 } 133 134 /// dyn_cast<T>() - If the current value is of the specified pointer type, 135 /// return it, otherwise return null. 136 template<typename T> 137 T dyn_cast() const { 138 if (is<T>()) return get<T>(); 139 return T(); 140 } 141 142 /// \brief If the union is set to the first pointer type get an address 143 /// pointing to it. 144 PT1 const *getAddrOfPtr1() const { 145 return const_cast<PointerUnion *>(this)->getAddrOfPtr1(); 146 } 147 148 /// \brief If the union is set to the first pointer type get an address 149 /// pointing to it. 150 PT1 *getAddrOfPtr1() { 151 assert(is<PT1>() && "Val is not the first pointer"); 152 assert(get<PT1>() == Val.getPointer() && 153 "Can't get the address because PointerLikeTypeTraits changes the ptr"); 154 return (PT1 *)Val.getAddrOfPointer(); 155 } 156 157 /// Assignment operators - Allow assigning into this union from either 158 /// pointer type, setting the discriminator to remember what it came from. 159 const PointerUnion &operator=(const PT1 &RHS) { 160 Val.initWithPointer( 161 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(RHS))); 162 return *this; 163 } 164 const PointerUnion &operator=(const PT2 &RHS) { 165 Val.setPointerAndInt( 166 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(RHS)), 167 1); 168 return *this; 169 } 170 171 void *getOpaqueValue() const { return Val.getOpaqueValue(); } 172 static inline PointerUnion getFromOpaqueValue(void *VP) { 173 PointerUnion V; 174 V.Val = ValTy::getFromOpaqueValue(VP); 175 return V; 176 } 177 }; 178 179 template<typename PT1, typename PT2> 180 static bool operator==(PointerUnion<PT1, PT2> lhs, 181 PointerUnion<PT1, PT2> rhs) { 182 return lhs.getOpaqueValue() == rhs.getOpaqueValue(); 183 } 184 185 template<typename PT1, typename PT2> 186 static bool operator!=(PointerUnion<PT1, PT2> lhs, 187 PointerUnion<PT1, PT2> rhs) { 188 return lhs.getOpaqueValue() != rhs.getOpaqueValue(); 189 } 190 191 // Teach SmallPtrSet that PointerUnion is "basically a pointer", that has 192 // # low bits available = min(PT1bits,PT2bits)-1. 193 template<typename PT1, typename PT2> 194 class PointerLikeTypeTraits<PointerUnion<PT1, PT2> > { 195 public: 196 static inline void * 197 getAsVoidPointer(const PointerUnion<PT1, PT2> &P) { 198 return P.getOpaqueValue(); 199 } 200 static inline PointerUnion<PT1, PT2> 201 getFromVoidPointer(void *P) { 202 return PointerUnion<PT1, PT2>::getFromOpaqueValue(P); 203 } 204 205 // The number of bits available are the min of the two pointer types. 206 enum { 207 NumLowBitsAvailable = 208 PointerLikeTypeTraits<typename PointerUnion<PT1,PT2>::ValTy> 209 ::NumLowBitsAvailable 210 }; 211 }; 212 213 214 /// PointerUnion3 - This is a pointer union of three pointer types. See 215 /// documentation for PointerUnion for usage. 216 template <typename PT1, typename PT2, typename PT3> 217 class PointerUnion3 { 218 public: 219 typedef PointerUnion<PT1, PT2> InnerUnion; 220 typedef PointerUnion<InnerUnion, PT3> ValTy; 221 private: 222 ValTy Val; 223 224 struct IsInnerUnion { 225 ValTy Val; 226 IsInnerUnion(ValTy val) : Val(val) { } 227 template<typename T> 228 int is() const { 229 return Val.template is<InnerUnion>() && 230 Val.template get<InnerUnion>().template is<T>(); 231 } 232 template<typename T> 233 T get() const { 234 return Val.template get<InnerUnion>().template get<T>(); 235 } 236 }; 237 238 struct IsPT3 { 239 ValTy Val; 240 IsPT3(ValTy val) : Val(val) { } 241 template<typename T> 242 int is() const { 243 return Val.template is<T>(); 244 } 245 template<typename T> 246 T get() const { 247 return Val.template get<T>(); 248 } 249 }; 250 251 public: 252 PointerUnion3() {} 253 254 PointerUnion3(PT1 V) { 255 Val = InnerUnion(V); 256 } 257 PointerUnion3(PT2 V) { 258 Val = InnerUnion(V); 259 } 260 PointerUnion3(PT3 V) { 261 Val = V; 262 } 263 264 /// isNull - Return true if the pointer held in the union is null, 265 /// regardless of which type it is. 266 bool isNull() const { return Val.isNull(); } 267 LLVM_EXPLICIT operator bool() const { return !isNull(); } 268 269 /// is<T>() return true if the Union currently holds the type matching T. 270 template<typename T> 271 int is() const { 272 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3. 273 typedef typename 274 ::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion, 275 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 > 276 >::Return Ty; 277 return Ty(Val).template is<T>(); 278 } 279 280 /// get<T>() - Return the value of the specified pointer type. If the 281 /// specified pointer type is incorrect, assert. 282 template<typename T> 283 T get() const { 284 assert(is<T>() && "Invalid accessor called"); 285 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3. 286 typedef typename 287 ::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion, 288 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 > 289 >::Return Ty; 290 return Ty(Val).template get<T>(); 291 } 292 293 /// dyn_cast<T>() - If the current value is of the specified pointer type, 294 /// return it, otherwise return null. 295 template<typename T> 296 T dyn_cast() const { 297 if (is<T>()) return get<T>(); 298 return T(); 299 } 300 301 /// Assignment operators - Allow assigning into this union from either 302 /// pointer type, setting the discriminator to remember what it came from. 303 const PointerUnion3 &operator=(const PT1 &RHS) { 304 Val = InnerUnion(RHS); 305 return *this; 306 } 307 const PointerUnion3 &operator=(const PT2 &RHS) { 308 Val = InnerUnion(RHS); 309 return *this; 310 } 311 const PointerUnion3 &operator=(const PT3 &RHS) { 312 Val = RHS; 313 return *this; 314 } 315 316 void *getOpaqueValue() const { return Val.getOpaqueValue(); } 317 static inline PointerUnion3 getFromOpaqueValue(void *VP) { 318 PointerUnion3 V; 319 V.Val = ValTy::getFromOpaqueValue(VP); 320 return V; 321 } 322 }; 323 324 // Teach SmallPtrSet that PointerUnion3 is "basically a pointer", that has 325 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2. 326 template<typename PT1, typename PT2, typename PT3> 327 class PointerLikeTypeTraits<PointerUnion3<PT1, PT2, PT3> > { 328 public: 329 static inline void * 330 getAsVoidPointer(const PointerUnion3<PT1, PT2, PT3> &P) { 331 return P.getOpaqueValue(); 332 } 333 static inline PointerUnion3<PT1, PT2, PT3> 334 getFromVoidPointer(void *P) { 335 return PointerUnion3<PT1, PT2, PT3>::getFromOpaqueValue(P); 336 } 337 338 // The number of bits available are the min of the two pointer types. 339 enum { 340 NumLowBitsAvailable = 341 PointerLikeTypeTraits<typename PointerUnion3<PT1, PT2, PT3>::ValTy> 342 ::NumLowBitsAvailable 343 }; 344 }; 345 346 /// PointerUnion4 - This is a pointer union of four pointer types. See 347 /// documentation for PointerUnion for usage. 348 template <typename PT1, typename PT2, typename PT3, typename PT4> 349 class PointerUnion4 { 350 public: 351 typedef PointerUnion<PT1, PT2> InnerUnion1; 352 typedef PointerUnion<PT3, PT4> InnerUnion2; 353 typedef PointerUnion<InnerUnion1, InnerUnion2> ValTy; 354 private: 355 ValTy Val; 356 public: 357 PointerUnion4() {} 358 359 PointerUnion4(PT1 V) { 360 Val = InnerUnion1(V); 361 } 362 PointerUnion4(PT2 V) { 363 Val = InnerUnion1(V); 364 } 365 PointerUnion4(PT3 V) { 366 Val = InnerUnion2(V); 367 } 368 PointerUnion4(PT4 V) { 369 Val = InnerUnion2(V); 370 } 371 372 /// isNull - Return true if the pointer held in the union is null, 373 /// regardless of which type it is. 374 bool isNull() const { return Val.isNull(); } 375 LLVM_EXPLICIT operator bool() const { return !isNull(); } 376 377 /// is<T>() return true if the Union currently holds the type matching T. 378 template<typename T> 379 int is() const { 380 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2. 381 typedef typename 382 ::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1, 383 ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 > 384 >::Return Ty; 385 return Val.template is<Ty>() && 386 Val.template get<Ty>().template is<T>(); 387 } 388 389 /// get<T>() - Return the value of the specified pointer type. If the 390 /// specified pointer type is incorrect, assert. 391 template<typename T> 392 T get() const { 393 assert(is<T>() && "Invalid accessor called"); 394 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2. 395 typedef typename 396 ::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1, 397 ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 > 398 >::Return Ty; 399 return Val.template get<Ty>().template get<T>(); 400 } 401 402 /// dyn_cast<T>() - If the current value is of the specified pointer type, 403 /// return it, otherwise return null. 404 template<typename T> 405 T dyn_cast() const { 406 if (is<T>()) return get<T>(); 407 return T(); 408 } 409 410 /// Assignment operators - Allow assigning into this union from either 411 /// pointer type, setting the discriminator to remember what it came from. 412 const PointerUnion4 &operator=(const PT1 &RHS) { 413 Val = InnerUnion1(RHS); 414 return *this; 415 } 416 const PointerUnion4 &operator=(const PT2 &RHS) { 417 Val = InnerUnion1(RHS); 418 return *this; 419 } 420 const PointerUnion4 &operator=(const PT3 &RHS) { 421 Val = InnerUnion2(RHS); 422 return *this; 423 } 424 const PointerUnion4 &operator=(const PT4 &RHS) { 425 Val = InnerUnion2(RHS); 426 return *this; 427 } 428 429 void *getOpaqueValue() const { return Val.getOpaqueValue(); } 430 static inline PointerUnion4 getFromOpaqueValue(void *VP) { 431 PointerUnion4 V; 432 V.Val = ValTy::getFromOpaqueValue(VP); 433 return V; 434 } 435 }; 436 437 // Teach SmallPtrSet that PointerUnion4 is "basically a pointer", that has 438 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2. 439 template<typename PT1, typename PT2, typename PT3, typename PT4> 440 class PointerLikeTypeTraits<PointerUnion4<PT1, PT2, PT3, PT4> > { 441 public: 442 static inline void * 443 getAsVoidPointer(const PointerUnion4<PT1, PT2, PT3, PT4> &P) { 444 return P.getOpaqueValue(); 445 } 446 static inline PointerUnion4<PT1, PT2, PT3, PT4> 447 getFromVoidPointer(void *P) { 448 return PointerUnion4<PT1, PT2, PT3, PT4>::getFromOpaqueValue(P); 449 } 450 451 // The number of bits available are the min of the two pointer types. 452 enum { 453 NumLowBitsAvailable = 454 PointerLikeTypeTraits<typename PointerUnion4<PT1, PT2, PT3, PT4>::ValTy> 455 ::NumLowBitsAvailable 456 }; 457 }; 458} 459 460#endif 461