include/llvm/IR/ValueMap.h

   1 //===- ValueMap.h - Safe map from Values to data ----------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file defines the ValueMap class.  ValueMap maps Value* or any subclass
  10 // to an arbitrary other type.  It provides the DenseMap interface but updates
  11 // itself to remain safe when keys are RAUWed or deleted.  By default, when a
  12 // key is RAUWed from V1 to V2, the old mapping V1->target is removed, and a new
  13 // mapping V2->target is added.  If V2 already existed, its old target is
  14 // overwritten.  When a key is deleted, its mapping is removed.
  15 //
  16 // You can override a ValueMap's Config parameter to control exactly what
  17 // happens on RAUW and destruction and to get called back on each event.  It's
  18 // legal to call back into the ValueMap from a Config's callbacks.  Config
  19 // parameters should inherit from ValueMapConfig<KeyT> to get default
  20 // implementations of all the methods ValueMap uses.  See ValueMapConfig for
  21 // documentation of the functions you can override.
  22 //
  23 //===----------------------------------------------------------------------===//
  24
  25 #ifndef LLVM_IR_VALUEMAP_H
  26 #define LLVM_IR_VALUEMAP_H
  27
  28 #include "llvm/ADT/DenseMap.h"
  29 #include "llvm/ADT/DenseMapInfo.h"
  30 #include "llvm/ADT/None.h"
  31 #include "llvm/ADT/Optional.h"
  32 #include "llvm/IR/TrackingMDRef.h"
  33 #include "llvm/IR/ValueHandle.h"
  34 #include "llvm/Support/Casting.h"
  35 #include "llvm/Support/Mutex.h"
  36 #include "llvm/Support/UniqueLock.h"
  37 #include <algorithm>
  38 #include <cassert>
  39 #include <cstddef>
  40 #include <iterator>
  41 #include <type_traits>
  42 #include <utility>
  43
  44 namespace llvm {
  45
  46 template<typename KeyT, typename ValueT, typename Config>
  47 class ValueMapCallbackVH;
  48 template<typename DenseMapT, typename KeyT>
  49 class ValueMapIterator;
  50 template<typename DenseMapT, typename KeyT>
  51 class ValueMapConstIterator;
  52
  53 /// This class defines the default behavior for configurable aspects of
  54 /// ValueMap<>.  User Configs should inherit from this class to be as compatible
  55 /// as possible with future versions of ValueMap.
  56 template<typename KeyT, typename MutexT = sys::Mutex>
  57 struct ValueMapConfig {
  58   using mutex_type = MutexT;
  59
  60   /// If FollowRAUW is true, the ValueMap will update mappings on RAUW. If it's
  61   /// false, the ValueMap will leave the original mapping in place.
  62   enum { FollowRAUW = true };
  63
  64   // All methods will be called with a first argument of type ExtraData.  The
  65   // default implementations in this class take a templated first argument so
  66   // that users' subclasses can use any type they want without having to
  67   // override all the defaults.
  68   struct ExtraData {};
  69
  70   template<typename ExtraDataT>
  71   static void onRAUW(const ExtraDataT & /*Data*/, KeyT /*Old*/, KeyT /*New*/) {}
  72   template<typename ExtraDataT>
  73   static void onDelete(const ExtraDataT &/*Data*/, KeyT /*Old*/) {}
  74
  75   /// Returns a mutex that should be acquired around any changes to the map.
  76   /// This is only acquired from the CallbackVH (and held around calls to onRAUW
  77   /// and onDelete) and not inside other ValueMap methods.  NULL means that no
  78   /// mutex is necessary.
  79   template<typename ExtraDataT>
  80   static mutex_type *getMutex(const ExtraDataT &/*Data*/) { return nullptr; }
  81 };
  82
  83 /// See the file comment.
  84 template<typename KeyT, typename ValueT, typename Config =ValueMapConfig<KeyT>>
  85 class ValueMap {
  86   friend class ValueMapCallbackVH<KeyT, ValueT, Config>;
  87
  88   using ValueMapCVH = ValueMapCallbackVH<KeyT, ValueT, Config>;
  89   using MapT = DenseMap<ValueMapCVH, ValueT, DenseMapInfo<ValueMapCVH>>;
  90   using MDMapT = DenseMap<const Metadata *, TrackingMDRef>;
  91   using ExtraData = typename Config::ExtraData;
  92
  93   MapT Map;
  94   Optional<MDMapT> MDMap;
  95   ExtraData Data;
  96   bool MayMapMetadata = true;
  97
  98 public:
  99   using key_type = KeyT;
 100   using mapped_type = ValueT;
 101   using value_type = std::pair<KeyT, ValueT>;
 102   using size_type = unsigned;
 103
 104   explicit ValueMap(unsigned NumInitBuckets = 64)
 105       : Map(NumInitBuckets), Data() {}
 106   explicit ValueMap(const ExtraData &Data, unsigned NumInitBuckets = 64)
 107       : Map(NumInitBuckets), Data(Data) {}
 108   // ValueMap can't be copied nor moved, beucase the callbacks store pointer
 109   // to it.
 110   ValueMap(const ValueMap &) = delete;
 111   ValueMap(ValueMap &&) = delete;
 112   ValueMap &operator=(const ValueMap &) = delete;
 113   ValueMap &operator=(ValueMap &&) = delete;
 114
 115   bool hasMD() const { return bool(MDMap); }
 116   MDMapT &MD() {
 117     if (!MDMap)
 118       MDMap.emplace();
 119     return *MDMap;
 120   }
 121   Optional<MDMapT> &getMDMap() { return MDMap; }
 122
 123   bool mayMapMetadata() const { return MayMapMetadata; }
 124   void enableMapMetadata() { MayMapMetadata = true; }
 125   void disableMapMetadata() { MayMapMetadata = false; }
 126
 127   /// Get the mapped metadata, if it's in the map.
 128   Optional<Metadata *> getMappedMD(const Metadata *MD) const {
 129     if (!MDMap)
 130       return None;
 131     auto Where = MDMap->find(MD);
 132     if (Where == MDMap->end())
 133       return None;
 134     return Where->second.get();
 135   }
 136
 137   using iterator = ValueMapIterator<MapT, KeyT>;
 138   using const_iterator = ValueMapConstIterator<MapT, KeyT>;
 139
 140   inline iterator begin() { return iterator(Map.begin()); }
 141   inline iterator end() { return iterator(Map.end()); }
 142   inline const_iterator begin() const { return const_iterator(Map.begin()); }
 143   inline const_iterator end() const { return const_iterator(Map.end()); }
 144
 145   bool empty() const { return Map.empty(); }
 146   size_type size() const { return Map.size(); }
 147
 148   /// Grow the map so that it has at least Size buckets. Does not shrink
 149   void resize(size_t Size) { Map.resize(Size); }
 150
 151   void clear() {
 152     Map.clear();
 153     MDMap.reset();
 154   }
 155
 156   /// Return 1 if the specified key is in the map, 0 otherwise.
 157   size_type count(const KeyT &Val) const {
 158     return Map.find_as(Val) == Map.end() ? 0 : 1;
 159   }
 160
 161   iterator find(const KeyT &Val) {
 162     return iterator(Map.find_as(Val));
 163   }
 164   const_iterator find(const KeyT &Val) const {
 165     return const_iterator(Map.find_as(Val));
 166   }
 167
 168   /// lookup - Return the entry for the specified key, or a default
 169   /// constructed value if no such entry exists.
 170   ValueT lookup(const KeyT &Val) const {
 171     typename MapT::const_iterator I = Map.find_as(Val);
 172     return I != Map.end() ? I->second : ValueT();
 173   }
 174
 175   // Inserts key,value pair into the map if the key isn't already in the map.
 176   // If the key is already in the map, it returns false and doesn't update the
 177   // value.
 178   std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
 179     auto MapResult = Map.insert(std::make_pair(Wrap(KV.first), KV.second));
 180     return std::make_pair(iterator(MapResult.first), MapResult.second);
 181   }
 182
 183   std::pair<iterator, bool> insert(std::pair<KeyT, ValueT> &&KV) {
 184     auto MapResult =
 185         Map.insert(std::make_pair(Wrap(KV.first), std::move(KV.second)));
 186     return std::make_pair(iterator(MapResult.first), MapResult.second);
 187   }
 188
 189   /// insert - Range insertion of pairs.
 190   template<typename InputIt>
 191   void insert(InputIt I, InputIt E) {
 192     for (; I != E; ++I)
 193       insert(*I);
 194   }
 195
 196   bool erase(const KeyT &Val) {
 197     typename MapT::iterator I = Map.find_as(Val);
 198     if (I == Map.end())
 199       return false;
 200
 201     Map.erase(I);
 202     return true;
 203   }
 204   void erase(iterator I) {
 205     return Map.erase(I.base());
 206   }
 207
 208   value_type& FindAndConstruct(const KeyT &Key) {
 209     return Map.FindAndConstruct(Wrap(Key));
 210   }
 211
 212   ValueT &operator[](const KeyT &Key) {
 213     return Map[Wrap(Key)];
 214   }
 215
 216   /// isPointerIntoBucketsArray - Return true if the specified pointer points
 217   /// somewhere into the ValueMap's array of buckets (i.e. either to a key or
 218   /// value in the ValueMap).
 219   bool isPointerIntoBucketsArray(const void *Ptr) const {
 220     return Map.isPointerIntoBucketsArray(Ptr);
 221   }
 222
 223   /// getPointerIntoBucketsArray() - Return an opaque pointer into the buckets
 224   /// array.  In conjunction with the previous method, this can be used to
 225   /// determine whether an insertion caused the ValueMap to reallocate.
 226   const void *getPointerIntoBucketsArray() const {
 227     return Map.getPointerIntoBucketsArray();
 228   }
 229
 230 private:
 231   // Takes a key being looked up in the map and wraps it into a
 232   // ValueMapCallbackVH, the actual key type of the map.  We use a helper
 233   // function because ValueMapCVH is constructed with a second parameter.
 234   ValueMapCVH Wrap(KeyT key) const {
 235     // The only way the resulting CallbackVH could try to modify *this (making
 236     // the const_cast incorrect) is if it gets inserted into the map.  But then
 237     // this function must have been called from a non-const method, making the
 238     // const_cast ok.
 239     return ValueMapCVH(key, const_cast<ValueMap*>(this));
 240   }
 241 };
 242
 243 // This CallbackVH updates its ValueMap when the contained Value changes,
 244 // according to the user's preferences expressed through the Config object.
 245 template <typename KeyT, typename ValueT, typename Config>
 246 class ValueMapCallbackVH final : public CallbackVH {
 247   friend class ValueMap<KeyT, ValueT, Config>;
 248   friend struct DenseMapInfo<ValueMapCallbackVH>;
 249
 250   using ValueMapT = ValueMap<KeyT, ValueT, Config>;
 251   using KeySansPointerT = typename std::remove_pointer<KeyT>::type;
 252
 253   ValueMapT *Map;
 254
 255   ValueMapCallbackVH(KeyT Key, ValueMapT *Map)
 256       : CallbackVH(const_cast<Value*>(static_cast<const Value*>(Key))),
 257         Map(Map) {}
 258
 259   // Private constructor used to create empty/tombstone DenseMap keys.
 260   ValueMapCallbackVH(Value *V) : CallbackVH(V), Map(nullptr) {}
 261
 262 public:
 263   KeyT Unwrap() const { return cast_or_null<KeySansPointerT>(getValPtr()); }
 264
 265   void deleted() override {
 266     // Make a copy that won't get changed even when *this is destroyed.
 267     ValueMapCallbackVH Copy(*this);
 268     typename Config::mutex_type *M = Config::getMutex(Copy.Map->Data);
 269     unique_lock<typename Config::mutex_type> Guard;
 270     if (M)
 271       Guard = unique_lock<typename Config::mutex_type>(*M);
 272     Config::onDelete(Copy.Map->Data, Copy.Unwrap());  // May destroy *this.
 273     Copy.Map->Map.erase(Copy);  // Definitely destroys *this.
 274   }
 275
 276   void allUsesReplacedWith(Value *new_key) override {
 277     assert(isa<KeySansPointerT>(new_key) &&
 278            "Invalid RAUW on key of ValueMap<>");
 279     // Make a copy that won't get changed even when *this is destroyed.
 280     ValueMapCallbackVH Copy(*this);
 281     typename Config::mutex_type *M = Config::getMutex(Copy.Map->Data);
 282     unique_lock<typename Config::mutex_type> Guard;
 283     if (M)
 284       Guard = unique_lock<typename Config::mutex_type>(*M);
 285
 286     KeyT typed_new_key = cast<KeySansPointerT>(new_key);
 287     // Can destroy *this:
 288     Config::onRAUW(Copy.Map->Data, Copy.Unwrap(), typed_new_key);
 289     if (Config::FollowRAUW) {
 290       typename ValueMapT::MapT::iterator I = Copy.Map->Map.find(Copy);
 291       // I could == Copy.Map->Map.end() if the onRAUW callback already
 292       // removed the old mapping.
 293       if (I != Copy.Map->Map.end()) {
 294         ValueT Target(std::move(I->second));
 295         Copy.Map->Map.erase(I);  // Definitely destroys *this.
 296         Copy.Map->insert(std::make_pair(typed_new_key, std::move(Target)));
 297       }
 298     }
 299   }
 300 };
 301
 302 template<typename KeyT, typename ValueT, typename Config>
 303 struct DenseMapInfo<ValueMapCallbackVH<KeyT, ValueT, Config>> {
 304   using VH = ValueMapCallbackVH<KeyT, ValueT, Config>;
 305
 306   static inline VH getEmptyKey() {
 307     return VH(DenseMapInfo<Value *>::getEmptyKey());
 308   }
 309
 310   static inline VH getTombstoneKey() {
 311     return VH(DenseMapInfo<Value *>::getTombstoneKey());
 312   }
 313
 314   static unsigned getHashValue(const VH &Val) {
 315     return DenseMapInfo<KeyT>::getHashValue(Val.Unwrap());
 316   }
 317
 318   static unsigned getHashValue(const KeyT &Val) {
 319     return DenseMapInfo<KeyT>::getHashValue(Val);
 320   }
 321
 322   static bool isEqual(const VH &LHS, const VH &RHS) {
 323     return LHS == RHS;
 324   }
 325
 326   static bool isEqual(const KeyT &LHS, const VH &RHS) {
 327     return LHS == RHS.getValPtr();
 328   }
 329 };
 330
 331 template<typename DenseMapT, typename KeyT>
 332 class ValueMapIterator :
 333     public std::iterator<std::forward_iterator_tag,
 334                          std::pair<KeyT, typename DenseMapT::mapped_type>,
 335                          ptrdiff_t> {
 336   using BaseT = typename DenseMapT::iterator;
 337   using ValueT = typename DenseMapT::mapped_type;
 338
 339   BaseT I;
 340
 341 public:
 342   ValueMapIterator() : I() {}
 343   ValueMapIterator(BaseT I) : I(I) {}
 344
 345   BaseT base() const { return I; }
 346
 347   struct ValueTypeProxy {
 348     const KeyT first;
 349     ValueT& second;
 350
 351     ValueTypeProxy *operator->() { return this; }
 352
 353     operator std::pair<KeyT, ValueT>() const {
 354       return std::make_pair(first, second);
 355     }
 356   };
 357
 358   ValueTypeProxy operator*() const {
 359     ValueTypeProxy Result = {I->first.Unwrap(), I->second};
 360     return Result;
 361   }
 362
 363   ValueTypeProxy operator->() const {
 364     return operator*();
 365   }
 366
 367   bool operator==(const ValueMapIterator &RHS) const {
 368     return I == RHS.I;
 369   }
 370   bool operator!=(const ValueMapIterator &RHS) const {
 371     return I != RHS.I;
 372   }
 373
 374   inline ValueMapIterator& operator++() {  // Preincrement
 375     ++I;
 376     return *this;
 377   }
 378   ValueMapIterator operator++(int) {  // Postincrement
 379     ValueMapIterator tmp = *this; ++*this; return tmp;
 380   }
 381 };
 382
 383 template<typename DenseMapT, typename KeyT>
 384 class ValueMapConstIterator :
 385     public std::iterator<std::forward_iterator_tag,
 386                          std::pair<KeyT, typename DenseMapT::mapped_type>,
 387                          ptrdiff_t> {
 388   using BaseT = typename DenseMapT::const_iterator;
 389   using ValueT = typename DenseMapT::mapped_type;
 390
 391   BaseT I;
 392
 393 public:
 394   ValueMapConstIterator() : I() {}
 395   ValueMapConstIterator(BaseT I) : I(I) {}
 396   ValueMapConstIterator(ValueMapIterator<DenseMapT, KeyT> Other)
 397     : I(Other.base()) {}
 398
 399   BaseT base() const { return I; }
 400
 401   struct ValueTypeProxy {
 402     const KeyT first;
 403     const ValueT& second;
 404     ValueTypeProxy *operator->() { return this; }
 405     operator std::pair<KeyT, ValueT>() const {
 406       return std::make_pair(first, second);
 407     }
 408   };
 409
 410   ValueTypeProxy operator*() const {
 411     ValueTypeProxy Result = {I->first.Unwrap(), I->second};
 412     return Result;
 413   }
 414
 415   ValueTypeProxy operator->() const {
 416     return operator*();
 417   }
 418
 419   bool operator==(const ValueMapConstIterator &RHS) const {
 420     return I == RHS.I;
 421   }
 422   bool operator!=(const ValueMapConstIterator &RHS) const {
 423     return I != RHS.I;
 424   }
 425
 426   inline ValueMapConstIterator& operator++() {  // Preincrement
 427     ++I;
 428     return *this;
 429   }
 430   ValueMapConstIterator operator++(int) {  // Postincrement
 431     ValueMapConstIterator tmp = *this; ++*this; return tmp;
 432   }
 433 };
 434
 435 } // end namespace llvm
 436
 437 #endif // LLVM_IR_VALUEMAP_H