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