1 //===- llvm/ADT/PointerUnion.h - Discriminated Union of 2 Ptrs --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the PointerUnion class, which is a discriminated union of
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_ADT_POINTERUNION_H
16 #define LLVM_ADT_POINTERUNION_H
18 #include "llvm/ADT/DenseMapInfo.h"
19 #include "llvm/ADT/PointerIntPair.h"
20 #include "llvm/Support/Compiler.h"
25 struct PointerUnionTypeSelectorReturn {
29 /// \brief Get a type based on whether two types are the same or not. For:
31 /// typedef typename PointerUnionTypeSelector<T1, T2, EQ, NE>::Return Ret;
33 /// Ret will be EQ type if T1 is same as T2 or NE type otherwise.
34 template <typename T1, typename T2, typename RET_EQ, typename RET_NE>
35 struct PointerUnionTypeSelector {
36 typedef typename PointerUnionTypeSelectorReturn<RET_NE>::Return Return;
39 template <typename T, typename RET_EQ, typename RET_NE>
40 struct PointerUnionTypeSelector<T, T, RET_EQ, RET_NE> {
41 typedef typename PointerUnionTypeSelectorReturn<RET_EQ>::Return Return;
44 template <typename T1, typename T2, typename RET_EQ, typename RET_NE>
45 struct PointerUnionTypeSelectorReturn<
46 PointerUnionTypeSelector<T1, T2, RET_EQ, RET_NE> > {
47 typedef typename PointerUnionTypeSelector<T1, T2, RET_EQ, RET_NE>::Return
51 /// Provide PointerLikeTypeTraits for void* that is used by PointerUnion
52 /// for the two template arguments.
53 template <typename PT1, typename PT2>
54 class PointerUnionUIntTraits {
56 static inline void *getAsVoidPointer(void *P) { return P; }
57 static inline void *getFromVoidPointer(void *P) { return P; }
59 PT1BitsAv = (int)(PointerLikeTypeTraits<PT1>::NumLowBitsAvailable),
60 PT2BitsAv = (int)(PointerLikeTypeTraits<PT2>::NumLowBitsAvailable),
61 NumLowBitsAvailable = PT1BitsAv < PT2BitsAv ? PT1BitsAv : PT2BitsAv
65 /// PointerUnion - This implements a discriminated union of two pointer types,
66 /// and keeps the discriminator bit-mangled into the low bits of the pointer.
67 /// This allows the implementation to be extremely efficient in space, but
68 /// permits a very natural and type-safe API.
70 /// Common use patterns would be something like this:
71 /// PointerUnion<int*, float*> P;
73 /// printf("%d %d", P.is<int*>(), P.is<float*>()); // prints "1 0"
74 /// X = P.get<int*>(); // ok.
75 /// Y = P.get<float*>(); // runtime assertion failure.
76 /// Z = P.get<double*>(); // compile time failure.
78 /// Y = P.get<float*>(); // ok.
79 /// X = P.get<int*>(); // runtime assertion failure.
80 template <typename PT1, typename PT2>
83 typedef PointerIntPair<void*, 1, bool,
84 PointerUnionUIntTraits<PT1,PT2> > ValTy;
89 static const int Num = 0;
92 static const int Num = 1;
95 struct UNION_DOESNT_CONTAIN_TYPE { };
100 PointerUnion(PT1 V) : Val(
101 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(V))) {
103 PointerUnion(PT2 V) : Val(
104 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(V)), 1) {
107 /// isNull - Return true if the pointer held in the union is null,
108 /// regardless of which type it is.
109 bool isNull() const {
110 // Convert from the void* to one of the pointer types, to make sure that
111 // we recursively strip off low bits if we have a nested PointerUnion.
112 return !PointerLikeTypeTraits<PT1>::getFromVoidPointer(Val.getPointer());
114 LLVM_EXPLICIT operator bool() const { return !isNull(); }
116 /// is<T>() return true if the Union currently holds the type matching T.
120 ::llvm::PointerUnionTypeSelector<PT1, T, IsPT1,
121 ::llvm::PointerUnionTypeSelector<PT2, T, IsPT2,
122 UNION_DOESNT_CONTAIN_TYPE<T> > >::Return Ty;
124 return static_cast<int>(Val.getInt()) == TyNo;
127 /// get<T>() - Return the value of the specified pointer type. If the
128 /// specified pointer type is incorrect, assert.
131 assert(is<T>() && "Invalid accessor called");
132 return PointerLikeTypeTraits<T>::getFromVoidPointer(Val.getPointer());
135 /// dyn_cast<T>() - If the current value is of the specified pointer type,
136 /// return it, otherwise return null.
139 if (is<T>()) return get<T>();
143 /// \brief If the union is set to the first pointer type get an address
145 PT1 const *getAddrOfPtr1() const {
146 return const_cast<PointerUnion *>(this)->getAddrOfPtr1();
149 /// \brief If the union is set to the first pointer type get an address
151 PT1 *getAddrOfPtr1() {
152 assert(is<PT1>() && "Val is not the first pointer");
153 assert(get<PT1>() == Val.getPointer() &&
154 "Can't get the address because PointerLikeTypeTraits changes the ptr");
155 return (PT1 *)Val.getAddrOfPointer();
158 /// Assignment operators - Allow assigning into this union from either
159 /// pointer type, setting the discriminator to remember what it came from.
160 const PointerUnion &operator=(const PT1 &RHS) {
162 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(RHS)));
165 const PointerUnion &operator=(const PT2 &RHS) {
166 Val.setPointerAndInt(
167 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(RHS)),
172 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
173 static inline PointerUnion getFromOpaqueValue(void *VP) {
175 V.Val = ValTy::getFromOpaqueValue(VP);
180 template<typename PT1, typename PT2>
181 static bool operator==(PointerUnion<PT1, PT2> lhs,
182 PointerUnion<PT1, PT2> rhs) {
183 return lhs.getOpaqueValue() == rhs.getOpaqueValue();
186 template<typename PT1, typename PT2>
187 static bool operator!=(PointerUnion<PT1, PT2> lhs,
188 PointerUnion<PT1, PT2> rhs) {
189 return lhs.getOpaqueValue() != rhs.getOpaqueValue();
192 // Teach SmallPtrSet that PointerUnion is "basically a pointer", that has
193 // # low bits available = min(PT1bits,PT2bits)-1.
194 template<typename PT1, typename PT2>
195 class PointerLikeTypeTraits<PointerUnion<PT1, PT2> > {
198 getAsVoidPointer(const PointerUnion<PT1, PT2> &P) {
199 return P.getOpaqueValue();
201 static inline PointerUnion<PT1, PT2>
202 getFromVoidPointer(void *P) {
203 return PointerUnion<PT1, PT2>::getFromOpaqueValue(P);
206 // The number of bits available are the min of the two pointer types.
208 NumLowBitsAvailable =
209 PointerLikeTypeTraits<typename PointerUnion<PT1,PT2>::ValTy>
210 ::NumLowBitsAvailable
215 /// PointerUnion3 - This is a pointer union of three pointer types. See
216 /// documentation for PointerUnion for usage.
217 template <typename PT1, typename PT2, typename PT3>
218 class PointerUnion3 {
220 typedef PointerUnion<PT1, PT2> InnerUnion;
221 typedef PointerUnion<InnerUnion, PT3> ValTy;
225 struct IsInnerUnion {
227 IsInnerUnion(ValTy val) : Val(val) { }
230 return Val.template is<InnerUnion>() &&
231 Val.template get<InnerUnion>().template is<T>();
235 return Val.template get<InnerUnion>().template get<T>();
241 IsPT3(ValTy val) : Val(val) { }
244 return Val.template is<T>();
248 return Val.template get<T>();
255 PointerUnion3(PT1 V) {
258 PointerUnion3(PT2 V) {
261 PointerUnion3(PT3 V) {
265 /// isNull - Return true if the pointer held in the union is null,
266 /// regardless of which type it is.
267 bool isNull() const { return Val.isNull(); }
268 LLVM_EXPLICIT operator bool() const { return !isNull(); }
270 /// is<T>() return true if the Union currently holds the type matching T.
273 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
275 ::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion,
276 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 >
278 return Ty(Val).template is<T>();
281 /// get<T>() - Return the value of the specified pointer type. If the
282 /// specified pointer type is incorrect, assert.
285 assert(is<T>() && "Invalid accessor called");
286 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
288 ::llvm::PointerUnionTypeSelector<PT1, T, IsInnerUnion,
289 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3 >
291 return Ty(Val).template get<T>();
294 /// dyn_cast<T>() - If the current value is of the specified pointer type,
295 /// return it, otherwise return null.
298 if (is<T>()) return get<T>();
302 /// Assignment operators - Allow assigning into this union from either
303 /// pointer type, setting the discriminator to remember what it came from.
304 const PointerUnion3 &operator=(const PT1 &RHS) {
305 Val = InnerUnion(RHS);
308 const PointerUnion3 &operator=(const PT2 &RHS) {
309 Val = InnerUnion(RHS);
312 const PointerUnion3 &operator=(const PT3 &RHS) {
317 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
318 static inline PointerUnion3 getFromOpaqueValue(void *VP) {
320 V.Val = ValTy::getFromOpaqueValue(VP);
325 // Teach SmallPtrSet that PointerUnion3 is "basically a pointer", that has
326 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
327 template<typename PT1, typename PT2, typename PT3>
328 class PointerLikeTypeTraits<PointerUnion3<PT1, PT2, PT3> > {
331 getAsVoidPointer(const PointerUnion3<PT1, PT2, PT3> &P) {
332 return P.getOpaqueValue();
334 static inline PointerUnion3<PT1, PT2, PT3>
335 getFromVoidPointer(void *P) {
336 return PointerUnion3<PT1, PT2, PT3>::getFromOpaqueValue(P);
339 // The number of bits available are the min of the two pointer types.
341 NumLowBitsAvailable =
342 PointerLikeTypeTraits<typename PointerUnion3<PT1, PT2, PT3>::ValTy>
343 ::NumLowBitsAvailable
347 /// PointerUnion4 - This is a pointer union of four pointer types. See
348 /// documentation for PointerUnion for usage.
349 template <typename PT1, typename PT2, typename PT3, typename PT4>
350 class PointerUnion4 {
352 typedef PointerUnion<PT1, PT2> InnerUnion1;
353 typedef PointerUnion<PT3, PT4> InnerUnion2;
354 typedef PointerUnion<InnerUnion1, InnerUnion2> ValTy;
360 PointerUnion4(PT1 V) {
361 Val = InnerUnion1(V);
363 PointerUnion4(PT2 V) {
364 Val = InnerUnion1(V);
366 PointerUnion4(PT3 V) {
367 Val = InnerUnion2(V);
369 PointerUnion4(PT4 V) {
370 Val = InnerUnion2(V);
373 /// isNull - Return true if the pointer held in the union is null,
374 /// regardless of which type it is.
375 bool isNull() const { return Val.isNull(); }
376 LLVM_EXPLICIT operator bool() const { return !isNull(); }
378 /// is<T>() return true if the Union currently holds the type matching T.
381 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
383 ::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1,
384 ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 >
386 return Val.template is<Ty>() &&
387 Val.template get<Ty>().template is<T>();
390 /// get<T>() - Return the value of the specified pointer type. If the
391 /// specified pointer type is incorrect, assert.
394 assert(is<T>() && "Invalid accessor called");
395 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
397 ::llvm::PointerUnionTypeSelector<PT1, T, InnerUnion1,
398 ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1, InnerUnion2 >
400 return Val.template get<Ty>().template get<T>();
403 /// dyn_cast<T>() - If the current value is of the specified pointer type,
404 /// return it, otherwise return null.
407 if (is<T>()) return get<T>();
411 /// Assignment operators - Allow assigning into this union from either
412 /// pointer type, setting the discriminator to remember what it came from.
413 const PointerUnion4 &operator=(const PT1 &RHS) {
414 Val = InnerUnion1(RHS);
417 const PointerUnion4 &operator=(const PT2 &RHS) {
418 Val = InnerUnion1(RHS);
421 const PointerUnion4 &operator=(const PT3 &RHS) {
422 Val = InnerUnion2(RHS);
425 const PointerUnion4 &operator=(const PT4 &RHS) {
426 Val = InnerUnion2(RHS);
430 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
431 static inline PointerUnion4 getFromOpaqueValue(void *VP) {
433 V.Val = ValTy::getFromOpaqueValue(VP);
438 // Teach SmallPtrSet that PointerUnion4 is "basically a pointer", that has
439 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
440 template<typename PT1, typename PT2, typename PT3, typename PT4>
441 class PointerLikeTypeTraits<PointerUnion4<PT1, PT2, PT3, PT4> > {
444 getAsVoidPointer(const PointerUnion4<PT1, PT2, PT3, PT4> &P) {
445 return P.getOpaqueValue();
447 static inline PointerUnion4<PT1, PT2, PT3, PT4>
448 getFromVoidPointer(void *P) {
449 return PointerUnion4<PT1, PT2, PT3, PT4>::getFromOpaqueValue(P);
452 // The number of bits available are the min of the two pointer types.
454 NumLowBitsAvailable =
455 PointerLikeTypeTraits<typename PointerUnion4<PT1, PT2, PT3, PT4>::ValTy>
456 ::NumLowBitsAvailable
460 // Teach DenseMap how to use PointerUnions as keys.
461 template<typename T, typename U>
462 struct DenseMapInfo<PointerUnion<T, U> > {
463 typedef PointerUnion<T, U> Pair;
464 typedef DenseMapInfo<T> FirstInfo;
465 typedef DenseMapInfo<U> SecondInfo;
467 static inline Pair getEmptyKey() {
468 return Pair(FirstInfo::getEmptyKey());
470 static inline Pair getTombstoneKey() {
471 return Pair(FirstInfo::getTombstoneKey());
473 static unsigned getHashValue(const Pair &PairVal) {
474 intptr_t key = (intptr_t)PairVal.getOpaqueValue();
475 return DenseMapInfo<intptr_t>::getHashValue(key);
477 static bool isEqual(const Pair &LHS, const Pair &RHS) {
478 return LHS.template is<T>() == RHS.template is<T>() &&
479 (LHS.template is<T>() ?
480 FirstInfo::isEqual(LHS.template get<T>(),
481 RHS.template get<T>()) :
482 SecondInfo::isEqual(LHS.template get<U>(),
483 RHS.template get<U>()));