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 = (int)(PointerLikeTypeTraits<PT1>::NumLowBitsAvailable), 58 PT2BitsAv = (int)(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) : Val( 99 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(V))) { 100 } 101 PointerUnion(PT2 V) : Val( 102 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(V)), 1) { 103 } 104 105 /// isNull - Return true if the pointer held in the union is null, 106 /// regardless of which type it is. 107 bool isNull() const { 108 // Convert from the void* to one of the pointer types, to make sure that 109 // we recursively strip off low bits if we have a nested PointerUnion. 110 return !PointerLikeTypeTraits<PT1>::getFromVoidPointer(Val.getPointer()); 111 } 112 operator bool() const { return !isNull(); } 113 114 /// is<T>() return true if the Union currently holds the type matching T. 115 template<typename T> 116 int is() const { 117 typedef typename 118 ::llvm::PointerUnionTypeSelector<PT1, T, IsPT1, 119 ::llvm::PointerUnionTypeSelector<PT2, T, IsPT2, 120 UNION_DOESNT_CONTAIN_TYPE<T> > >::Return Ty; 121 int TyNo = Ty::Num; 122 return static_cast<int>(Val.getInt()) == TyNo; 123 } 124 125 /// get<T>() - Return the value of the specified pointer type. If the 126 /// specified pointer type is incorrect, assert. 127 template<typename T> 128 T get() const { 129 assert(is<T>() && "Invalid accessor called"); 130 return PointerLikeTypeTraits<T>::getFromVoidPointer(Val.getPointer()); 131 } 132 133 /// dyn_cast<T>() - If the current value is of the specified pointer type, 134 /// return it, otherwise return null. 135 template<typename T> 136 T dyn_cast() const { 137 if (is<T>()) return get<T>(); 138 return T(); 139 } 140 141 /// \brief If the union is set to the first pointer type get an address 142 /// pointing to it. 143 PT1 const *getAddrOfPtr1() const { 144 return const_cast<PointerUnion *>(this)->getAddrOfPtr1(); 145 } 146 147 /// \brief If the union is set to the first pointer type get an address 148 /// pointing to it. 149 PT1 *getAddrOfPtr1() { 150 assert(is<PT1>() && "Val is not the first pointer"); 151 assert(get<PT1>() == Val.getPointer() && 152 "Can't get the address because PointerLikeTypeTraits changes the ptr"); 153 return (PT1 *)Val.getAddrOfPointer(); 154 } 155 156 /// Assignment operators - Allow assigning into this union from either 157 /// pointer type, setting the discriminator to remember what it came from. 158 const PointerUnion &operator=(const PT1 &RHS) { 159 Val.initWithPointer( 160 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(RHS))); 161 return *this; 162 } 163 const PointerUnion &operator=(const PT2 &RHS) { 164 Val.setPointerAndInt( 165 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(RHS)), 166 1); 167 return *this; 168 } 169 170 void *getOpaqueValue() const { return Val.getOpaqueValue(); } 171 static inline PointerUnion getFromOpaqueValue(void *VP) { 172 PointerUnion V; 173 V.Val = ValTy::getFromOpaqueValue(VP); 174 return V; 175 } 176 }; 177 178 // Teach SmallPtrSet that PointerUnion is "basically a pointer", that has 179 // # low bits available = min(PT1bits,PT2bits)-1. 180 template<typename PT1, typename PT2> 181 class PointerLikeTypeTraits<PointerUnion<PT1, PT2> > { 182 public: 183 static inline void * 184 getAsVoidPointer(const PointerUnion<PT1, PT2> &P) { 185 return P.getOpaqueValue(); 186 } 187 static inline PointerUnion<PT1, PT2> 188 getFromVoidPointer(void *P) { 189 return PointerUnion<PT1, PT2>::getFromOpaqueValue(P); 190 } 191 192 // The number of bits available are the min of the two pointer types. 193 enum { 194 NumLowBitsAvailable = 195 PointerLikeTypeTraits<typename PointerUnion<PT1,PT2>::ValTy> 196 ::NumLowBitsAvailable 197 }; 198 }; 199 200 201 /// PointerUnion3 - This is a pointer union of three pointer types. See 202 /// documentation for PointerUnion for usage. 203 template <typename PT1, typename PT2, typename PT3> 204 class PointerUnion3 { 205 public: 206 typedef PointerUnion<PT1, PT2> InnerUnion; 207 typedef PointerUnion<InnerUnion, PT3> ValTy; 208 private: 209 ValTy Val; 210 211 struct IsInnerUnion { 212 ValTy Val; 213 IsInnerUnion(ValTy val) : Val(val) { } 214 template<typename T> 215 int is() const { 216 return Val.template is<InnerUnion>() && 217 Val.template get<InnerUnion>().template is<T>(); 218 } 219 template<typename T> 220 T get() const { 221 return Val.template get<InnerUnion>().template get<T>(); 222 } 223 }; 224 225 struct IsPT3 { 226 ValTy Val; 227 IsPT3(ValTy val) : Val(val) { } 228 template<typename T> 229 int is() const { 230 return Val.template is<T>(); 231 } 232 template<typename T> 233 T get() const { 234 return Val.template get<T>(); 235 } 236 }; 237 238 public: 239 PointerUnion3() {} 240 241 PointerUnion3(PT1 V) { 242 Val = InnerUnion(V); 243 } 244 PointerUnion3(PT2 V) { 245 Val = InnerUnion(V); 246 } 247 PointerUnion3(PT3 V) { 248 Val = V; 249 } 250 251 /// isNull - Return true if the pointer held in the union is null, 252 /// regardless of which type it is. 253 bool isNull() const { return Val.isNull(); } 254 operator bool() const { return !isNull(); } 255 256 /// is<T>() return true if the Union currently holds the type matching T. 257 template<typename T> 258 int is() const { 259 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3. 260 typedef typename 261 ::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion, 262 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 > 263 >::Return Ty; 264 return Ty(Val).template is<T>(); 265 } 266 267 /// get<T>() - Return the value of the specified pointer type. If the 268 /// specified pointer type is incorrect, assert. 269 template<typename T> 270 T get() const { 271 assert(is<T>() && "Invalid accessor called"); 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 get<T>(); 278 } 279 280 /// dyn_cast<T>() - If the current value is of the specified pointer type, 281 /// return it, otherwise return null. 282 template<typename T> 283 T dyn_cast() const { 284 if (is<T>()) return get<T>(); 285 return T(); 286 } 287 288 /// Assignment operators - Allow assigning into this union from either 289 /// pointer type, setting the discriminator to remember what it came from. 290 const PointerUnion3 &operator=(const PT1 &RHS) { 291 Val = InnerUnion(RHS); 292 return *this; 293 } 294 const PointerUnion3 &operator=(const PT2 &RHS) { 295 Val = InnerUnion(RHS); 296 return *this; 297 } 298 const PointerUnion3 &operator=(const PT3 &RHS) { 299 Val = RHS; 300 return *this; 301 } 302 303 void *getOpaqueValue() const { return Val.getOpaqueValue(); } 304 static inline PointerUnion3 getFromOpaqueValue(void *VP) { 305 PointerUnion3 V; 306 V.Val = ValTy::getFromOpaqueValue(VP); 307 return V; 308 } 309 }; 310 311 // Teach SmallPtrSet that PointerUnion3 is "basically a pointer", that has 312 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2. 313 template<typename PT1, typename PT2, typename PT3> 314 class PointerLikeTypeTraits<PointerUnion3<PT1, PT2, PT3> > { 315 public: 316 static inline void * 317 getAsVoidPointer(const PointerUnion3<PT1, PT2, PT3> &P) { 318 return P.getOpaqueValue(); 319 } 320 static inline PointerUnion3<PT1, PT2, PT3> 321 getFromVoidPointer(void *P) { 322 return PointerUnion3<PT1, PT2, PT3>::getFromOpaqueValue(P); 323 } 324 325 // The number of bits available are the min of the two pointer types. 326 enum { 327 NumLowBitsAvailable = 328 PointerLikeTypeTraits<typename PointerUnion3<PT1, PT2, PT3>::ValTy> 329 ::NumLowBitsAvailable 330 }; 331 }; 332 333 /// PointerUnion4 - This is a pointer union of four pointer types. See 334 /// documentation for PointerUnion for usage. 335 template <typename PT1, typename PT2, typename PT3, typename PT4> 336 class PointerUnion4 { 337 public: 338 typedef PointerUnion<PT1, PT2> InnerUnion1; 339 typedef PointerUnion<PT3, PT4> InnerUnion2; 340 typedef PointerUnion<InnerUnion1, InnerUnion2> ValTy; 341 private: 342 ValTy Val; 343 public: 344 PointerUnion4() {} 345 346 PointerUnion4(PT1 V) { 347 Val = InnerUnion1(V); 348 } 349 PointerUnion4(PT2 V) { 350 Val = InnerUnion1(V); 351 } 352 PointerUnion4(PT3 V) { 353 Val = InnerUnion2(V); 354 } 355 PointerUnion4(PT4 V) { 356 Val = InnerUnion2(V); 357 } 358 359 /// isNull - Return true if the pointer held in the union is null, 360 /// regardless of which type it is. 361 bool isNull() const { return Val.isNull(); } 362 operator bool() const { return !isNull(); } 363 364 /// is<T>() return true if the Union currently holds the type matching T. 365 template<typename T> 366 int is() const { 367 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2. 368 typedef typename 369 ::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1, 370 ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 > 371 >::Return Ty; 372 return Val.template is<Ty>() && 373 Val.template get<Ty>().template is<T>(); 374 } 375 376 /// get<T>() - Return the value of the specified pointer type. If the 377 /// specified pointer type is incorrect, assert. 378 template<typename T> 379 T get() const { 380 assert(is<T>() && "Invalid accessor called"); 381 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2. 382 typedef typename 383 ::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1, 384 ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 > 385 >::Return Ty; 386 return Val.template get<Ty>().template get<T>(); 387 } 388 389 /// dyn_cast<T>() - If the current value is of the specified pointer type, 390 /// return it, otherwise return null. 391 template<typename T> 392 T dyn_cast() const { 393 if (is<T>()) return get<T>(); 394 return T(); 395 } 396 397 /// Assignment operators - Allow assigning into this union from either 398 /// pointer type, setting the discriminator to remember what it came from. 399 const PointerUnion4 &operator=(const PT1 &RHS) { 400 Val = InnerUnion1(RHS); 401 return *this; 402 } 403 const PointerUnion4 &operator=(const PT2 &RHS) { 404 Val = InnerUnion1(RHS); 405 return *this; 406 } 407 const PointerUnion4 &operator=(const PT3 &RHS) { 408 Val = InnerUnion2(RHS); 409 return *this; 410 } 411 const PointerUnion4 &operator=(const PT4 &RHS) { 412 Val = InnerUnion2(RHS); 413 return *this; 414 } 415 416 void *getOpaqueValue() const { return Val.getOpaqueValue(); } 417 static inline PointerUnion4 getFromOpaqueValue(void *VP) { 418 PointerUnion4 V; 419 V.Val = ValTy::getFromOpaqueValue(VP); 420 return V; 421 } 422 }; 423 424 // Teach SmallPtrSet that PointerUnion4 is "basically a pointer", that has 425 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2. 426 template<typename PT1, typename PT2, typename PT3, typename PT4> 427 class PointerLikeTypeTraits<PointerUnion4<PT1, PT2, PT3, PT4> > { 428 public: 429 static inline void * 430 getAsVoidPointer(const PointerUnion4<PT1, PT2, PT3, PT4> &P) { 431 return P.getOpaqueValue(); 432 } 433 static inline PointerUnion4<PT1, PT2, PT3, PT4> 434 getFromVoidPointer(void *P) { 435 return PointerUnion4<PT1, PT2, PT3, PT4>::getFromOpaqueValue(P); 436 } 437 438 // The number of bits available are the min of the two pointer types. 439 enum { 440 NumLowBitsAvailable = 441 PointerLikeTypeTraits<typename PointerUnion4<PT1, PT2, PT3, PT4>::ValTy> 442 ::NumLowBitsAvailable 443 }; 444 }; 445 } 446 447 #endif 448
