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PointerUnion.h
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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/DenseMapInfo.h"
21 #include <cassert>
22 #include <cstddef>
23 #include <cstdint>
24 
25 namespace llvm {
26 
27 template <typename T> struct PointerUnionTypeSelectorReturn {
28  using Return = T;
29 };
30 
31 /// Get a type based on whether two types are the same or not.
32 ///
33 /// For:
34 ///
35 /// \code
36 /// using Ret = typename PointerUnionTypeSelector<T1, T2, EQ, NE>::Return;
37 /// \endcode
38 ///
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>
43 };
44 
45 template <typename T, typename RET_EQ, typename RET_NE>
46 struct PointerUnionTypeSelector<T, T, RET_EQ, RET_NE> {
48 };
49 
50 template <typename T1, typename T2, typename RET_EQ, typename RET_NE>
52  PointerUnionTypeSelector<T1, T2, RET_EQ, RET_NE>> {
53  using Return =
55 };
56 
57 /// Provide PointerLikeTypeTraits for void* that is used by PointerUnion
58 /// for the two template arguments.
59 template <typename PT1, typename PT2> class PointerUnionUIntTraits {
60 public:
61  static inline void *getAsVoidPointer(void *P) { return P; }
62  static inline void *getFromVoidPointer(void *P) { return P; }
63 
64  enum {
67  NumLowBitsAvailable = PT1BitsAv < PT2BitsAv ? PT1BitsAv : PT2BitsAv
68  };
69 };
70 
71 /// A discriminated union of two pointer types, with the discriminator in the
72 /// low bit of the pointer.
73 ///
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.
76 ///
77 /// Common use patterns would be something like this:
78 /// PointerUnion<int*, float*> P;
79 /// P = (int*)0;
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.
84 /// P = (float*)0;
85 /// Y = P.get<float*>(); // ok.
86 /// X = P.get<int*>(); // runtime assertion failure.
87 template <typename PT1, typename PT2> class PointerUnion {
88 public:
89  using ValTy =
91 
92 private:
93  ValTy Val;
94 
95  struct IsPT1 {
96  static const int Num = 0;
97  };
98  struct IsPT2 {
99  static const int Num = 1;
100  };
101  template <typename T> struct UNION_DOESNT_CONTAIN_TYPE {};
102 
103 public:
104  PointerUnion() = default;
106  : Val(const_cast<void *>(
107  PointerLikeTypeTraits<PT1>::getAsVoidPointer(V))) {}
109  : Val(const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(V)),
110  1) {}
111 
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.
118  }
119 
120  explicit operator bool() const { return !isNull(); }
121 
122  /// Test if the Union currently holds the type matching T.
123  template <typename T> int is() const {
124  using Ty = typename ::llvm::PointerUnionTypeSelector<
125  PT1, T, IsPT1,
127  UNION_DOESNT_CONTAIN_TYPE<T>>>::Return;
128  int TyNo = Ty::Num;
129  return static_cast<int>(Val.getInt()) == TyNo;
130  }
131 
132  /// Returns the value of the specified pointer type.
133  ///
134  /// If the specified pointer type is incorrect, assert.
135  template <typename T> T get() const {
136  assert(is<T>() && "Invalid accessor called");
138  }
139 
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 {
143  if (is<T>())
144  return get<T>();
145  return T();
146  }
147 
148  /// If the union is set to the first pointer type get an address pointing to
149  /// it.
150  PT1 const *getAddrOfPtr1() const {
151  return const_cast<PointerUnion *>(this)->getAddrOfPtr1();
152  }
153 
154  /// If the union is set to the first pointer type get an address pointing to
155  /// it.
156  PT1 *getAddrOfPtr1() {
157  assert(is<PT1>() && "Val is not the first pointer");
158  assert(
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()));
163  }
164 
165  /// Assignment from nullptr which just clears the union.
166  const PointerUnion &operator=(std::nullptr_t) {
167  Val.initWithPointer(nullptr);
168  return *this;
169  }
170 
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) {
174  Val.initWithPointer(
175  const_cast<void *>(PointerLikeTypeTraits<PT1>::getAsVoidPointer(RHS)));
176  return *this;
177  }
178  const PointerUnion &operator=(const PT2 &RHS) {
179  Val.setPointerAndInt(
180  const_cast<void *>(PointerLikeTypeTraits<PT2>::getAsVoidPointer(RHS)),
181  1);
182  return *this;
183  }
184 
185  void *getOpaqueValue() const { return Val.getOpaqueValue(); }
186  static inline PointerUnion getFromOpaqueValue(void *VP) {
187  PointerUnion V;
188  V.Val = ValTy::getFromOpaqueValue(VP);
189  return V;
190  }
191 };
192 
193 template <typename PT1, typename PT2>
195  return lhs.getOpaqueValue() == rhs.getOpaqueValue();
196 }
197 
198 template <typename PT1, typename PT2>
200  return lhs.getOpaqueValue() != rhs.getOpaqueValue();
201 }
202 
203 template <typename PT1, typename PT2>
204 bool operator<(PointerUnion<PT1, PT2> lhs, PointerUnion<PT1, PT2> rhs) {
205  return lhs.getOpaqueValue() < rhs.getOpaqueValue();
206 }
207 
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>
212  static inline void *getAsVoidPointer(const PointerUnion<PT1, PT2> &P) {
213  return P.getOpaqueValue();
214  }
215 
218  }
219 
220  // The number of bits available are the min of the two pointer types.
221  enum {
222  NumLowBitsAvailable = PointerLikeTypeTraits<
223  typename PointerUnion<PT1, PT2>::ValTy>::NumLowBitsAvailable
224  };
225 };
226 
227 /// A pointer union of three pointer types. See documentation for PointerUnion
228 /// for usage.
229 template <typename PT1, typename PT2, typename PT3> class PointerUnion3 {
230 public:
233 
234 private:
235  ValTy Val;
236 
237  struct IsInnerUnion {
238  ValTy Val;
239 
240  IsInnerUnion(ValTy val) : Val(val) {}
241 
242  template <typename T> int is() const {
243  return Val.template is<InnerUnion>() &&
244  Val.template get<InnerUnion>().template is<T>();
245  }
246 
247  template <typename T> T get() const {
248  return Val.template get<InnerUnion>().template get<T>();
249  }
250  };
251 
252  struct IsPT3 {
253  ValTy Val;
254 
255  IsPT3(ValTy val) : Val(val) {}
256 
257  template <typename T> int is() const { return Val.template is<T>(); }
258  template <typename T> T get() const { return Val.template get<T>(); }
259  };
260 
261 public:
262  PointerUnion3() = default;
263  PointerUnion3(PT1 V) { Val = InnerUnion(V); }
264  PointerUnion3(PT2 V) { Val = InnerUnion(V); }
265  PointerUnion3(PT3 V) { Val = V; }
266 
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(); }
271 
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,
278  return Ty(Val).template is<T>();
279  }
280 
281  /// Returns the value of the specified pointer type.
282  ///
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,
290  return Ty(Val).template get<T>();
291  }
292 
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 {
296  if (is<T>())
297  return get<T>();
298  return T();
299  }
300 
301  /// Assignment from nullptr which just clears the union.
302  const PointerUnion3 &operator=(std::nullptr_t) {
303  Val = nullptr;
304  return *this;
305  }
306 
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);
311  return *this;
312  }
313  const PointerUnion3 &operator=(const PT2 &RHS) {
314  Val = InnerUnion(RHS);
315  return *this;
316  }
317  const PointerUnion3 &operator=(const PT3 &RHS) {
318  Val = RHS;
319  return *this;
320  }
321 
322  void *getOpaqueValue() const { return Val.getOpaqueValue(); }
323  static inline PointerUnion3 getFromOpaqueValue(void *VP) {
324  PointerUnion3 V;
325  V.Val = ValTy::getFromOpaqueValue(VP);
326  return V;
327  }
328 };
329 
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();
336  }
337 
340  }
341 
342  // The number of bits available are the min of the two pointer types.
343  enum {
344  NumLowBitsAvailable = PointerLikeTypeTraits<
345  typename PointerUnion3<PT1, PT2, PT3>::ValTy>::NumLowBitsAvailable
346  };
347 };
348 
349 /// A pointer union of four pointer types. See documentation for PointerUnion
350 /// for usage.
351 template <typename PT1, typename PT2, typename PT3, typename PT4>
353 public:
357 
358 private:
359  ValTy Val;
360 
361 public:
362  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); }
367 
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(); }
372 
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  using Ty = typename ::llvm::PointerUnionTypeSelector<
377  PT1, T, InnerUnion1,
378  ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1,
380  return Val.template is<Ty>() && Val.template get<Ty>().template is<T>();
381  }
382 
383  /// Returns the value of the specified pointer type.
384  ///
385  /// If the specified pointer type is incorrect, assert.
386  template <typename T> T get() const {
387  assert(is<T>() && "Invalid accessor called");
388  // If T is PT1/PT2 choose InnerUnion1 otherwise choose InnerUnion2.
389  using Ty = typename ::llvm::PointerUnionTypeSelector<
390  PT1, T, InnerUnion1,
391  ::llvm::PointerUnionTypeSelector<PT2, T, InnerUnion1,
393  return Val.template get<Ty>().template get<T>();
394  }
395 
396  /// Returns the current pointer if it is of the specified pointer type,
397  /// otherwises returns null.
398  template <typename T> T dyn_cast() const {
399  if (is<T>())
400  return get<T>();
401  return T();
402  }
403 
404  /// Assignment from nullptr which just clears the union.
405  const PointerUnion4 &operator=(std::nullptr_t) {
406  Val = nullptr;
407  return *this;
408  }
409 
410  /// Assignment operators - Allow assigning into this union from either
411  /// pointer type, setting the discriminator to remember what it came from.
412  const PointerUnion4 &operator=(const PT1 &RHS) {
413  Val = InnerUnion1(RHS);
414  return *this;
415  }
416  const PointerUnion4 &operator=(const PT2 &RHS) {
417  Val = InnerUnion1(RHS);
418  return *this;
419  }
420  const PointerUnion4 &operator=(const PT3 &RHS) {
421  Val = InnerUnion2(RHS);
422  return *this;
423  }
424  const PointerUnion4 &operator=(const PT4 &RHS) {
425  Val = InnerUnion2(RHS);
426  return *this;
427  }
428 
429  void *getOpaqueValue() const { return Val.getOpaqueValue(); }
430  static inline PointerUnion4 getFromOpaqueValue(void *VP) {
431  PointerUnion4 V;
432  V.Val = ValTy::getFromOpaqueValue(VP);
433  return V;
434  }
435 };
436 
437 // Teach SmallPtrSet that PointerUnion4 is "basically a pointer", that has
438 // # low bits available = min(PT1bits,PT2bits,PT2bits)-2.
439 template <typename PT1, typename PT2, typename PT3, typename PT4>
440 struct PointerLikeTypeTraits<PointerUnion4<PT1, PT2, PT3, PT4>> {
441  static inline void *
443  return P.getOpaqueValue();
444  }
445 
448  }
449 
450  // The number of bits available are the min of the two pointer types.
451  enum {
452  NumLowBitsAvailable = PointerLikeTypeTraits<
453  typename PointerUnion4<PT1, PT2, PT3, PT4>::ValTy>::NumLowBitsAvailable
454  };
455 };
456 
457 // Teach DenseMap how to use PointerUnions as keys.
458 template <typename T, typename U> struct DenseMapInfo<PointerUnion<T, U>> {
462 
463  static inline Pair getEmptyKey() { return Pair(FirstInfo::getEmptyKey()); }
464 
465  static inline Pair getTombstoneKey() {
466  return Pair(FirstInfo::getTombstoneKey());
467  }
468 
469  static unsigned getHashValue(const Pair &PairVal) {
470  intptr_t key = (intptr_t)PairVal.getOpaqueValue();
472  }
473 
474  static bool isEqual(const Pair &LHS, const Pair &RHS) {
475  return LHS.template is<T>() == RHS.template is<T>() &&
476  (LHS.template is<T>() ? FirstInfo::isEqual(LHS.template get<T>(),
477  RHS.template get<T>())
478  : SecondInfo::isEqual(LHS.template get<U>(),
479  RHS.template get<U>()));
480  }
481 };
482 
483 } // end namespace llvm
484 
485 #endif // LLVM_ADT_POINTERUNION_H
static void * getAsVoidPointer(const PointerUnion3< PT1, PT2, PT3 > &P)
Definition: PointerUnion.h:334
const PointerUnion4 & operator=(const PT3 &RHS)
Definition: PointerUnion.h:420
Provide PointerLikeTypeTraits for void* that is used by PointerUnion for the two template arguments...
Definition: PointerUnion.h:59
const PointerUnion4 & operator=(const PT1 &RHS)
Assignment operators - Allow assigning into this union from either pointer type, setting the discrimi...
Definition: PointerUnion.h:412
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
PointerTy getPointer() const
int is() const
Test if the Union currently holds the type matching T.
Definition: PointerUnion.h:374
const PointerUnion & operator=(const PT1 &RHS)
Assignment operators - Allow assigning into this union from either pointer type, setting the discrimi...
Definition: PointerUnion.h:173
PT1 * getAddrOfPtr1()
If the union is set to the first pointer type get an address pointing to it.
Definition: PointerUnion.h:156
static PointerUnion4 getFromOpaqueValue(void *VP)
Definition: PointerUnion.h:430
static void * getAsVoidPointer(const PointerUnion< PT1, PT2 > &P)
Definition: PointerUnion.h:212
const PointerUnion & operator=(const PT2 &RHS)
Definition: PointerUnion.h:178
static unsigned getHashValue(const Pair &PairVal)
Definition: PointerUnion.h:469
T dyn_cast() const
Returns the current pointer if it is of the specified pointer type, otherwises returns null...
Definition: PointerUnion.h:295
static PointerUnion getFromOpaqueValue(void *VP)
Definition: PointerUnion.h:186
bool isNull() const
Test if the pointer held in the union is null, regardless of which type it is.
Definition: PointerUnion.h:114
static void * getAsVoidPointer(void *P)
Definition: PointerUnion.h:61
typename PointerUnionTypeSelectorReturn< RET_EQ >::Return Return
Definition: PointerUnion.h:47
PointerTy const * getAddrOfPointer() const
void * getOpaqueValue() const
Definition: PointerUnion.h:429
void * getOpaqueValue() const
PT1 const * getAddrOfPtr1() const
If the union is set to the first pointer type get an address pointing to it.
Definition: PointerUnion.h:150
static void * getAsVoidPointer(const PointerUnion4< PT1, PT2, PT3, PT4 > &P)
Definition: PointerUnion.h:442
Get a type based on whether two types are the same or not.
Definition: PointerUnion.h:41
const PointerUnion3 & operator=(std::nullptr_t)
Assignment from nullptr which just clears the union.
Definition: PointerUnion.h:302
A traits type that is used to handle pointer types and things that are just wrappers for pointers as ...
void * getOpaqueValue() const
Definition: PointerUnion.h:185
static bool isEqual(const Function &Caller, const Function &Callee)
IntType getInt() const
#define T
const PointerUnion3 & operator=(const PT3 &RHS)
Definition: PointerUnion.h:317
typename PointerUnionTypeSelector< T1, T2, RET_EQ, RET_NE >::Return Return
Definition: PointerUnion.h:54
const PointerUnion4 & operator=(const PT2 &RHS)
Definition: PointerUnion.h:416
#define P(N)
const PointerUnion & operator=(std::nullptr_t)
Assignment from nullptr which just clears the union.
Definition: PointerUnion.h:166
bool isNull() const
Test if the pointer held in the union is null, regardless of which type it is.
Definition: PointerUnion.h:269
void initWithPointer(PointerTy PtrVal)
void * getOpaqueValue() const
Definition: PointerUnion.h:322
typename PointerUnionTypeSelectorReturn< RET_NE >::Return Return
Definition: PointerUnion.h:42
const PointerUnion3 & operator=(const PT1 &RHS)
Assignment operators - Allow assigning into this union from either pointer type, setting the discrimi...
Definition: PointerUnion.h:309
const PointerUnion4 & operator=(const PT4 &RHS)
Definition: PointerUnion.h:424
T dyn_cast() const
Returns the current pointer if it is of the specified pointer type, otherwises returns null...
Definition: PointerUnion.h:142
bool isNull() const
Test if the pointer held in the union is null, regardless of which type it is.
Definition: PointerUnion.h:370
static PointerUnion3 getFromOpaqueValue(void *VP)
Definition: PointerUnion.h:323
const PointerUnion4 & operator=(std::nullptr_t)
Assignment from nullptr which just clears the union.
Definition: PointerUnion.h:405
int is() const
Test if the Union currently holds the type matching T.
Definition: PointerUnion.h:273
static PointerUnion< PT1, PT2 > getFromVoidPointer(void *P)
Definition: PointerUnion.h:216
void setPointerAndInt(PointerTy PtrVal, IntType IntVal)
bool operator!=(uint64_t V1, const APInt &V2)
Definition: APInt.h:1948
A pointer union of three pointer types.
Definition: PointerUnion.h:229
T dyn_cast() const
Returns the current pointer if it is of the specified pointer type, otherwises returns null...
Definition: PointerUnion.h:398
static PointerUnion3< PT1, PT2, PT3 > getFromVoidPointer(void *P)
Definition: PointerUnion.h:338
const PointerUnion3 & operator=(const PT2 &RHS)
Definition: PointerUnion.h:313
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
bool isNull(StringRef S)
Definition: YAMLTraits.h:488
static bool isEqual(const Pair &LHS, const Pair &RHS)
Definition: PointerUnion.h:474
int is() const
Test if the Union currently holds the type matching T.
Definition: PointerUnion.h:123
bool operator==(uint64_t V1, const APInt &V2)
Definition: APInt.h:1946
static void * getFromVoidPointer(void *P)
Definition: PointerUnion.h:62
#define T1
static PointerUnion4< PT1, PT2, PT3, PT4 > getFromVoidPointer(void *P)
Definition: PointerUnion.h:446
A pointer union of four pointer types.
Definition: PointerUnion.h:352
A discriminated union of two pointer types, with the discriminator in the low bit of the pointer...
Definition: PointerUnion.h:87