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/PointerLikeTypeTraits.h"
27 template <typename T> struct PointerUnionTypeSelectorReturn {
31 /// Get a type based on whether two types are the same or not.
36 /// using Ret = typename PointerUnionTypeSelector<T1, T2, EQ, NE>::Return;
39 /// Ret will be EQ type if T1 is same as T2 or NE type otherwise.
40 template <typename T1, typename T2, typename RET_EQ, typename RET_NE>
41 struct PointerUnionTypeSelector {
42 using Return = typename PointerUnionTypeSelectorReturn<RET_NE>::Return;
45 template <typename T, typename RET_EQ, typename RET_NE>
46 struct PointerUnionTypeSelector<T, T, RET_EQ, RET_NE> {
47 using Return = typename PointerUnionTypeSelectorReturn<RET_EQ>::Return;
50 template <typename T1, typename T2, typename RET_EQ, typename RET_NE>
51 struct PointerUnionTypeSelectorReturn<
52 PointerUnionTypeSelector<T1, T2, RET_EQ, RET_NE>> {
54 typename PointerUnionTypeSelector<T1, T2, RET_EQ, RET_NE>::Return;
57 /// Provide PointerLikeTypeTraits for void* that is used by PointerUnion
58 /// for the two template arguments.
59 template <typename PT1, typename PT2> class PointerUnionUIntTraits {
61 static inline void *getAsVoidPointer(void *P) { return P; }
62 static inline void *getFromVoidPointer(void *P) { return P; }
65 PT1BitsAv = (int)(PointerLikeTypeTraits<PT1>::NumLowBitsAvailable),
66 PT2BitsAv = (int)(PointerLikeTypeTraits<PT2>::NumLowBitsAvailable),
67 NumLowBitsAvailable = PT1BitsAv < PT2BitsAv ? PT1BitsAv : PT2BitsAv
71 /// A discriminated union of two pointer types, with the discriminator in the
72 /// low bit of the pointer.
74 /// This implementation is extremely efficient in space due to leveraging the
75 /// low bits of the pointer, while exposing a natural and type-safe API.
77 /// Common use patterns would be something like this:
78 /// PointerUnion<int*, float*> P;
80 /// printf("%d %d", P.is<int*>(), P.is<float*>()); // prints "1 0"
81 /// X = P.get<int*>(); // ok.
82 /// Y = P.get<float*>(); // runtime assertion failure.
83 /// Z = P.get<double*>(); // compile time failure.
85 /// Y = P.get<float*>(); // ok.
86 /// X = P.get<int*>(); // runtime assertion failure.
87 template <typename PT1, typename PT2> class PointerUnion {
90 PointerIntPair<void *, 1, bool, PointerUnionUIntTraits<PT1, PT2>>;
96 static const int Num = 0;
99 static const int Num = 1;
101 template <typename T> struct UNION_DOESNT_CONTAIN_TYPE {};
104 PointerUnion() = default;
106 : Val(const_cast<void *>(
107 PointerLikeTypeTraits<PT1>::getAsVoidPointer(V))) {}
109 : Val(const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(V)),
112 /// Test if the pointer held in the union is null, regardless of
113 /// which type it is.
114 bool isNull() const {
115 // Convert from the void* to one of the pointer types, to make sure that
116 // we recursively strip off low bits if we have a nested PointerUnion.
117 return !PointerLikeTypeTraits<PT1>::getFromVoidPointer(Val.getPointer());
120 explicit operator bool() const { return !isNull(); }
122 /// Test if the Union currently holds the type matching T.
123 template <typename T> int is() const {
124 using Ty = typename ::llvm::PointerUnionTypeSelector<
126 ::llvm::PointerUnionTypeSelector<PT2, T, IsPT2,
127 UNION_DOESNT_CONTAIN_TYPE<T>>>::Return;
129 return static_cast<int>(Val.getInt()) == TyNo;
132 /// Returns the value of the specified pointer type.
134 /// If the specified pointer type is incorrect, assert.
135 template <typename T> T get() const {
136 assert(is<T>() && "Invalid accessor called");
137 return PointerLikeTypeTraits<T>::getFromVoidPointer(Val.getPointer());
140 /// Returns the current pointer if it is of the specified pointer type,
141 /// otherwises returns null.
142 template <typename T> T dyn_cast() const {
148 /// If the union is set to the first pointer type get an address pointing to
150 PT1 const *getAddrOfPtr1() const {
151 return const_cast<PointerUnion *>(this)->getAddrOfPtr1();
154 /// If the union is set to the first pointer type get an address pointing to
156 PT1 *getAddrOfPtr1() {
157 assert(is<PT1>() && "Val is not the first pointer");
159 get<PT1>() == Val.getPointer() &&
160 "Can't get the address because PointerLikeTypeTraits changes the ptr");
161 return const_cast<PT1 *>(
162 reinterpret_cast<const PT1 *>(Val.getAddrOfPointer()));
165 /// Assignment from nullptr which just clears the union.
166 const PointerUnion &operator=(std::nullptr_t) {
167 Val.initWithPointer(nullptr);
171 /// Assignment operators - Allow assigning into this union from either
172 /// pointer type, setting the discriminator to remember what it came from.
173 const PointerUnion &operator=(const PT1 &RHS) {
175 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(RHS)));
178 const PointerUnion &operator=(const PT2 &RHS) {
179 Val.setPointerAndInt(
180 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(RHS)),
185 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
186 static inline PointerUnion getFromOpaqueValue(void *VP) {
188 V.Val = ValTy::getFromOpaqueValue(VP);
193 template <typename PT1, typename PT2>
194 bool operator==(PointerUnion<PT1, PT2> lhs, PointerUnion<PT1, PT2> rhs) {
195 return lhs.getOpaqueValue() == rhs.getOpaqueValue();
198 template <typename PT1, typename PT2>
199 bool operator!=(PointerUnion<PT1, PT2> lhs, PointerUnion<PT1, PT2> rhs) {
200 return lhs.getOpaqueValue() != rhs.getOpaqueValue();
203 template <typename PT1, typename PT2>
204 bool operator<(PointerUnion<PT1, PT2> lhs, PointerUnion<PT1, PT2> rhs) {
205 return lhs.getOpaqueValue() < rhs.getOpaqueValue();
208 // Teach SmallPtrSet that PointerUnion is "basically a pointer", that has
209 // # low bits available = min(PT1bits,PT2bits)-1.
210 template <typename PT1, typename PT2>
211 struct PointerLikeTypeTraits<PointerUnion<PT1, PT2>> {
212 static inline void *getAsVoidPointer(const PointerUnion<PT1, PT2> &P) {
213 return P.getOpaqueValue();
216 static inline PointerUnion<PT1, PT2> getFromVoidPointer(void *P) {
217 return PointerUnion<PT1, PT2>::getFromOpaqueValue(P);
220 // The number of bits available are the min of the two pointer types.
222 NumLowBitsAvailable = PointerLikeTypeTraits<
223 typename PointerUnion<PT1, PT2>::ValTy>::NumLowBitsAvailable
227 /// A pointer union of three pointer types. See documentation for PointerUnion
229 template <typename PT1, typename PT2, typename PT3> class PointerUnion3 {
231 using InnerUnion = PointerUnion<PT1, PT2>;
232 using ValTy = PointerUnion<InnerUnion, PT3>;
237 struct IsInnerUnion {
240 IsInnerUnion(ValTy val) : Val(val) {}
242 template <typename T> int is() const {
243 return Val.template is<InnerUnion>() &&
244 Val.template get<InnerUnion>().template is<T>();
247 template <typename T> T get() const {
248 return Val.template get<InnerUnion>().template get<T>();
255 IsPT3(ValTy val) : Val(val) {}
257 template <typename T> int is() const { return Val.template is<T>(); }
258 template <typename T> T get() const { return Val.template get<T>(); }
262 PointerUnion3() = default;
263 PointerUnion3(PT1 V) { Val = InnerUnion(V); }
264 PointerUnion3(PT2 V) { Val = InnerUnion(V); }
265 PointerUnion3(PT3 V) { Val = V; }
267 /// Test if the pointer held in the union is null, regardless of
268 /// which type it is.
269 bool isNull() const { return Val.isNull(); }
270 explicit operator bool() const { return !isNull(); }
272 /// Test if the Union currently holds the type matching T.
273 template <typename T> int is() const {
274 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
275 using Ty = typename ::llvm::PointerUnionTypeSelector<
276 PT1, T, IsInnerUnion,
277 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3>>::Return;
278 return Ty(Val).template is<T>();
281 /// Returns the value of the specified pointer type.
283 /// If the specified pointer type is incorrect, assert.
284 template <typename T> T get() const {
285 assert(is<T>() && "Invalid accessor called");
286 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
287 using Ty = typename ::llvm::PointerUnionTypeSelector<
288 PT1, T, IsInnerUnion,
289 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3>>::Return;
290 return Ty(Val).template get<T>();
293 /// Returns the current pointer if it is of the specified pointer type,
294 /// otherwises returns null.
295 template <typename T> T dyn_cast() const {
301 /// Assignment from nullptr which just clears the union.
302 const PointerUnion3 &operator=(std::nullptr_t) {
307 /// Assignment operators - Allow assigning into this union from either
308 /// pointer type, setting the discriminator to remember what it came from.
309 const PointerUnion3 &operator=(const PT1 &RHS) {
310 Val = InnerUnion(RHS);
313 const PointerUnion3 &operator=(const PT2 &RHS) {
314 Val = InnerUnion(RHS);
317 const PointerUnion3 &operator=(const PT3 &RHS) {
322 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
323 static inline PointerUnion3 getFromOpaqueValue(void *VP) {
325 V.Val = ValTy::getFromOpaqueValue(VP);
330 // Teach SmallPtrSet that PointerUnion3 is "basically a pointer", that has
331 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
332 template <typename PT1, typename PT2, typename PT3>
333 struct PointerLikeTypeTraits<PointerUnion3<PT1, PT2, PT3>> {
334 static inline void *getAsVoidPointer(const PointerUnion3<PT1, PT2, PT3> &P) {
335 return P.getOpaqueValue();
338 static inline PointerUnion3<PT1, PT2, PT3> getFromVoidPointer(void *P) {
339 return PointerUnion3<PT1, PT2, PT3>::getFromOpaqueValue(P);
342 // The number of bits available are the min of the two pointer types.
344 NumLowBitsAvailable = PointerLikeTypeTraits<
345 typename PointerUnion3<PT1, PT2, PT3>::ValTy>::NumLowBitsAvailable
349 template <typename PT1, typename PT2, typename PT3>
350 bool operator<(PointerUnion3<PT1, PT2, PT3> lhs,
351 PointerUnion3<PT1, PT2, PT3> rhs) {
352 return lhs.getOpaqueValue() < rhs.getOpaqueValue();
355 /// A pointer union of four pointer types. See documentation for PointerUnion
357 template <typename PT1, typename PT2, typename PT3, typename PT4>
358 class PointerUnion4 {
360 using InnerUnion1 = PointerUnion<PT1, PT2>;
361 using InnerUnion2 = PointerUnion<PT3, PT4>;
362 using ValTy = PointerUnion<InnerUnion1, InnerUnion2>;
368 PointerUnion4() = default;
369 PointerUnion4(PT1 V) { Val = InnerUnion1(V); }
370 PointerUnion4(PT2 V) { Val = InnerUnion1(V); }
371 PointerUnion4(PT3 V) { Val = InnerUnion2(V); }
372 PointerUnion4(PT4 V) { Val = InnerUnion2(V); }
374 /// Test if the pointer held in the union is null, regardless of
375 /// which type it is.
376 bool isNull() const { return Val.isNull(); }
377 explicit operator bool() const { return !isNull(); }
379 /// Test if the Union currently holds the type matching T.
380 template <typename T> int is() const {
381 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
382 using Ty = typename ::llvm::PointerUnionTypeSelector<
384 ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1,
385 InnerUnion2>>::Return;
386 return Val.template is<Ty>() && Val.template get<Ty>().template is<T>();
389 /// Returns the value of the specified pointer type.
391 /// If the specified pointer type is incorrect, assert.
392 template <typename T> T get() const {
393 assert(is<T>() && "Invalid accessor called");
394 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
395 using Ty = typename ::llvm::PointerUnionTypeSelector<
397 ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1,
398 InnerUnion2>>::Return;
399 return Val.template get<Ty>().template get<T>();
402 /// Returns the current pointer if it is of the specified pointer type,
403 /// otherwises returns null.
404 template <typename T> T dyn_cast() const {
410 /// Assignment from nullptr which just clears the union.
411 const PointerUnion4 &operator=(std::nullptr_t) {
416 /// Assignment operators - Allow assigning into this union from either
417 /// pointer type, setting the discriminator to remember what it came from.
418 const PointerUnion4 &operator=(const PT1 &RHS) {
419 Val = InnerUnion1(RHS);
422 const PointerUnion4 &operator=(const PT2 &RHS) {
423 Val = InnerUnion1(RHS);
426 const PointerUnion4 &operator=(const PT3 &RHS) {
427 Val = InnerUnion2(RHS);
430 const PointerUnion4 &operator=(const PT4 &RHS) {
431 Val = InnerUnion2(RHS);
435 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
436 static inline PointerUnion4 getFromOpaqueValue(void *VP) {
438 V.Val = ValTy::getFromOpaqueValue(VP);
443 // Teach SmallPtrSet that PointerUnion4 is "basically a pointer", that has
444 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
445 template <typename PT1, typename PT2, typename PT3, typename PT4>
446 struct PointerLikeTypeTraits<PointerUnion4<PT1, PT2, PT3, PT4>> {
448 getAsVoidPointer(const PointerUnion4<PT1, PT2, PT3, PT4> &P) {
449 return P.getOpaqueValue();
452 static inline PointerUnion4<PT1, PT2, PT3, PT4> getFromVoidPointer(void *P) {
453 return PointerUnion4<PT1, PT2, PT3, PT4>::getFromOpaqueValue(P);
456 // The number of bits available are the min of the two pointer types.
458 NumLowBitsAvailable = PointerLikeTypeTraits<
459 typename PointerUnion4<PT1, PT2, PT3, PT4>::ValTy>::NumLowBitsAvailable
463 // Teach DenseMap how to use PointerUnions as keys.
464 template <typename T, typename U> struct DenseMapInfo<PointerUnion<T, U>> {
465 using Pair = PointerUnion<T, U>;
466 using FirstInfo = DenseMapInfo<T>;
467 using SecondInfo = DenseMapInfo<U>;
469 static inline Pair getEmptyKey() { return Pair(FirstInfo::getEmptyKey()); }
471 static inline Pair getTombstoneKey() {
472 return Pair(FirstInfo::getTombstoneKey());
475 static unsigned getHashValue(const Pair &PairVal) {
476 intptr_t key = (intptr_t)PairVal.getOpaqueValue();
477 return DenseMapInfo<intptr_t>::getHashValue(key);
480 static bool isEqual(const Pair &LHS, const Pair &RHS) {
481 return LHS.template is<T>() == RHS.template is<T>() &&
482 (LHS.template is<T>() ? FirstInfo::isEqual(LHS.template get<T>(),
483 RHS.template get<T>())
484 : SecondInfo::isEqual(LHS.template get<U>(),
485 RHS.template get<U>()));
489 } // end namespace llvm
491 #endif // LLVM_ADT_POINTERUNION_H