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 /// typedef typename PointerUnionTypeSelector<T1, T2, EQ, NE>::Return Ret;
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 typedef typename PointerUnionTypeSelectorReturn<RET_NE>::Return Return;
45 template <typename T, typename RET_EQ, typename RET_NE>
46 struct PointerUnionTypeSelector<T, T, RET_EQ, RET_NE> {
47 typedef typename PointerUnionTypeSelectorReturn<RET_EQ>::Return 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 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 {
89 typedef 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;
107 : Val(const_cast<void *>(
108 PointerLikeTypeTraits<PT1>::getAsVoidPointer(V))) {}
110 : Val(const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(V)),
113 /// Test if the pointer held in the union is null, regardless of
114 /// which type it is.
115 bool isNull() const {
116 // Convert from the void* to one of the pointer types, to make sure that
117 // we recursively strip off low bits if we have a nested PointerUnion.
118 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 typedef typename ::llvm::PointerUnionTypeSelector<
125 PT1, T, IsPT1, ::llvm::PointerUnionTypeSelector<
126 PT2, T, IsPT2, 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 *>(reinterpret_cast<const PT1 *>(Val.getAddrOfPointer()));
164 /// Assignment from nullptr which just clears the union.
165 const PointerUnion &operator=(std::nullptr_t) {
166 Val.initWithPointer(nullptr);
170 /// Assignment operators - Allow assigning into this union from either
171 /// pointer type, setting the discriminator to remember what it came from.
172 const PointerUnion &operator=(const PT1 &RHS) {
174 const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(RHS)));
177 const PointerUnion &operator=(const PT2 &RHS) {
178 Val.setPointerAndInt(
179 const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(RHS)),
184 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
185 static inline PointerUnion getFromOpaqueValue(void *VP) {
187 V.Val = ValTy::getFromOpaqueValue(VP);
192 template <typename PT1, typename PT2>
193 bool operator==(PointerUnion<PT1, PT2> lhs, PointerUnion<PT1, PT2> rhs) {
194 return lhs.getOpaqueValue() == rhs.getOpaqueValue();
197 template <typename PT1, typename PT2>
198 bool operator!=(PointerUnion<PT1, PT2> lhs, PointerUnion<PT1, PT2> rhs) {
199 return lhs.getOpaqueValue() != rhs.getOpaqueValue();
202 template <typename PT1, typename PT2>
203 bool operator<(PointerUnion<PT1, PT2> lhs, PointerUnion<PT1, PT2> rhs) {
204 return lhs.getOpaqueValue() < rhs.getOpaqueValue();
207 // Teach SmallPtrSet that PointerUnion is "basically a pointer", that has
208 // # low bits available = min(PT1bits,PT2bits)-1.
209 template <typename PT1, typename PT2>
210 class 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 typedef PointerUnion<PT1, PT2> InnerUnion;
232 typedef PointerUnion<InnerUnion, PT3> ValTy;
237 struct IsInnerUnion {
239 IsInnerUnion(ValTy val) : Val(val) {}
240 template <typename T> int is() const {
241 return Val.template is<InnerUnion>() &&
242 Val.template get<InnerUnion>().template is<T>();
244 template <typename T> T get() const {
245 return Val.template get<InnerUnion>().template get<T>();
251 IsPT3(ValTy val) : Val(val) {}
252 template <typename T> int is() const { return Val.template is<T>(); }
253 template <typename T> T get() const { return Val.template get<T>(); }
257 PointerUnion3() = default;
259 PointerUnion3(PT1 V) { Val = InnerUnion(V); }
260 PointerUnion3(PT2 V) { Val = InnerUnion(V); }
261 PointerUnion3(PT3 V) { Val = V; }
263 /// Test if the pointer held in the union is null, regardless of
264 /// which type it is.
265 bool isNull() const { return Val.isNull(); }
266 explicit operator bool() const { return !isNull(); }
268 /// Test if the Union currently holds the type matching T.
269 template <typename T> int is() const {
270 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
271 typedef typename ::llvm::PointerUnionTypeSelector<
272 PT1, T, IsInnerUnion,
273 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3>>::Return
275 return Ty(Val).template is<T>();
278 /// Returns the value of the specified pointer type.
280 /// If the specified pointer type is incorrect, assert.
281 template <typename T> T get() const {
282 assert(is<T>() && "Invalid accessor called");
283 // If T is PT1/PT2 choose IsInnerUnion otherwise choose IsPT3.
284 typedef typename ::llvm::PointerUnionTypeSelector<
285 PT1, T, IsInnerUnion,
286 ::llvm::PointerUnionTypeSelector<PT2, T, IsInnerUnion, IsPT3>>::Return
288 return Ty(Val).template get<T>();
291 /// Returns the current pointer if it is of the specified pointer type,
292 /// otherwises returns null.
293 template <typename T> T dyn_cast() const {
299 /// Assignment from nullptr which just clears the union.
300 const PointerUnion3 &operator=(std::nullptr_t) {
305 /// Assignment operators - Allow assigning into this union from either
306 /// pointer type, setting the discriminator to remember what it came from.
307 const PointerUnion3 &operator=(const PT1 &RHS) {
308 Val = InnerUnion(RHS);
311 const PointerUnion3 &operator=(const PT2 &RHS) {
312 Val = InnerUnion(RHS);
315 const PointerUnion3 &operator=(const PT3 &RHS) {
320 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
321 static inline PointerUnion3 getFromOpaqueValue(void *VP) {
323 V.Val = ValTy::getFromOpaqueValue(VP);
328 // Teach SmallPtrSet that PointerUnion3 is "basically a pointer", that has
329 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
330 template <typename PT1, typename PT2, typename PT3>
331 class PointerLikeTypeTraits<PointerUnion3<PT1, PT2, PT3>> {
333 static inline void *getAsVoidPointer(const PointerUnion3<PT1, PT2, PT3> &P) {
334 return P.getOpaqueValue();
337 static inline PointerUnion3<PT1, PT2, PT3> getFromVoidPointer(void *P) {
338 return PointerUnion3<PT1, PT2, PT3>::getFromOpaqueValue(P);
341 // The number of bits available are the min of the two pointer types.
343 NumLowBitsAvailable = PointerLikeTypeTraits<
344 typename PointerUnion3<PT1, PT2, PT3>::ValTy>::NumLowBitsAvailable
348 /// A pointer union of four pointer types. See documentation for PointerUnion
350 template <typename PT1, typename PT2, typename PT3, typename PT4>
351 class PointerUnion4 {
353 typedef PointerUnion<PT1, PT2> InnerUnion1;
354 typedef PointerUnion<PT3, PT4> InnerUnion2;
355 typedef PointerUnion<InnerUnion1, InnerUnion2> ValTy;
361 PointerUnion4() = default;
363 PointerUnion4(PT1 V) { Val = InnerUnion1(V); }
364 PointerUnion4(PT2 V) { Val = InnerUnion1(V); }
365 PointerUnion4(PT3 V) { Val = InnerUnion2(V); }
366 PointerUnion4(PT4 V) { Val = InnerUnion2(V); }
368 /// Test if the pointer held in the union is null, regardless of
369 /// which type it is.
370 bool isNull() const { return Val.isNull(); }
371 explicit operator bool() const { return !isNull(); }
373 /// Test if the Union currently holds the type matching T.
374 template <typename T> int is() const {
375 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
376 typedef typename ::llvm::PointerUnionTypeSelector<
377 PT1, T, InnerUnion1, ::llvm::PointerUnionTypeSelector<
378 PT2, T, InnerUnion1, InnerUnion2>>::Return Ty;
379 return Val.template is<Ty>() && Val.template get<Ty>().template is<T>();
382 /// Returns the value of the specified pointer type.
384 /// If the specified pointer type is incorrect, assert.
385 template <typename T> T get() const {
386 assert(is<T>() && "Invalid accessor called");
387 // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
388 typedef typename ::llvm::PointerUnionTypeSelector<
389 PT1, T, InnerUnion1, ::llvm::PointerUnionTypeSelector<
390 PT2, T, InnerUnion1, InnerUnion2>>::Return Ty;
391 return Val.template get<Ty>().template get<T>();
394 /// Returns the current pointer if it is of the specified pointer type,
395 /// otherwises returns null.
396 template <typename T> T dyn_cast() const {
402 /// Assignment from nullptr which just clears the union.
403 const PointerUnion4 &operator=(std::nullptr_t) {
408 /// Assignment operators - Allow assigning into this union from either
409 /// pointer type, setting the discriminator to remember what it came from.
410 const PointerUnion4 &operator=(const PT1 &RHS) {
411 Val = InnerUnion1(RHS);
414 const PointerUnion4 &operator=(const PT2 &RHS) {
415 Val = InnerUnion1(RHS);
418 const PointerUnion4 &operator=(const PT3 &RHS) {
419 Val = InnerUnion2(RHS);
422 const PointerUnion4 &operator=(const PT4 &RHS) {
423 Val = InnerUnion2(RHS);
427 void *getOpaqueValue() const { return Val.getOpaqueValue(); }
428 static inline PointerUnion4 getFromOpaqueValue(void *VP) {
430 V.Val = ValTy::getFromOpaqueValue(VP);
435 // Teach SmallPtrSet that PointerUnion4 is "basically a pointer", that has
436 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
437 template <typename PT1, typename PT2, typename PT3, typename PT4>
438 class PointerLikeTypeTraits<PointerUnion4<PT1, PT2, PT3, PT4>> {
441 getAsVoidPointer(const PointerUnion4<PT1, PT2, PT3, PT4> &P) {
442 return P.getOpaqueValue();
445 static inline PointerUnion4<PT1, PT2, PT3, PT4> getFromVoidPointer(void *P) {
446 return PointerUnion4<PT1, PT2, PT3, PT4>::getFromOpaqueValue(P);
449 // The number of bits available are the min of the two pointer types.
451 NumLowBitsAvailable = PointerLikeTypeTraits<
452 typename PointerUnion4<PT1, PT2, PT3, PT4>::ValTy>::NumLowBitsAvailable
456 // Teach DenseMap how to use PointerUnions as keys.
457 template <typename T, typename U> struct DenseMapInfo<PointerUnion<T, U>> {
458 typedef PointerUnion<T, U> Pair;
459 typedef DenseMapInfo<T> FirstInfo;
460 typedef DenseMapInfo<U> SecondInfo;
462 static inline Pair getEmptyKey() { return Pair(FirstInfo::getEmptyKey()); }
463 static inline Pair getTombstoneKey() {
464 return Pair(FirstInfo::getTombstoneKey());
466 static unsigned getHashValue(const Pair &PairVal) {
467 intptr_t key = (intptr_t)PairVal.getOpaqueValue();
468 return DenseMapInfo<intptr_t>::getHashValue(key);
470 static bool isEqual(const Pair &LHS, const Pair &RHS) {
471 return LHS.template is<T>() == RHS.template is<T>() &&
472 (LHS.template is<T>() ? FirstInfo::isEqual(LHS.template get<T>(),
473 RHS.template get<T>())
474 : SecondInfo::isEqual(LHS.template get<U>(),
475 RHS.template get<U>()));
479 } // end namespace llvm
481 #endif // LLVM_ADT_POINTERUNION_H