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 <algorithm>
  37 #include <cassert>
  38 #include <cstddef>
  39 #include <iterator>
  40 #include <mutex>
  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
  97 public:
  98   using key_type = KeyT;
  99   using mapped_type = ValueT;
 100   using value_type = std::pair<KeyT, ValueT>;
 101   using size_type = unsigned;
 102
 103   explicit ValueMap(unsigned NumInitBuckets = 64)
 104       : Map(NumInitBuckets), Data() {}
 105   explicit ValueMap(const ExtraData &Data, unsigned NumInitBuckets = 64)
 106       : Map(NumInitBuckets), Data(Data) {}
 107   // ValueMap can't be copied nor moved, beucase the callbacks store pointer
 108   // to it.
 109   ValueMap(const ValueMap &) = delete;
 110   ValueMap(ValueMap &&) = delete;
 111   ValueMap &operator=(const ValueMap &) = delete;
 112   ValueMap &operator=(ValueMap &&) = delete;
 113
 114   bool hasMD() const { return bool(MDMap); }
 115   MDMapT &MD() {
 116     if (!MDMap)
 117       MDMap.emplace();
 118     return *MDMap;
 119   }
 120   Optional<MDMapT> &getMDMap() { return MDMap; }
 121
 122   /// Get the mapped metadata, if it's in the map.
 123   Optional<Metadata *> getMappedMD(const Metadata *MD) const {
 124     if (!MDMap)
 125       return None;
 126     auto Where = MDMap->find(MD);
 127     if (Where == MDMap->end())
 128       return None;
 129     return Where->second.get();
 130   }
 131
 132   using iterator = ValueMapIterator<MapT, KeyT>;
 133   using const_iterator = ValueMapConstIterator<MapT, KeyT>;
 134
 135   inline iterator begin() { return iterator(Map.begin()); }
 136   inline iterator end() { return iterator(Map.end()); }
 137   inline const_iterator begin() const { return const_iterator(Map.begin()); }
 138   inline const_iterator end() const { return const_iterator(Map.end()); }
 139
 140   bool empty() const { return Map.empty(); }
 141   size_type size() const { return Map.size(); }
 142
 143   /// Grow the map so that it has at least Size buckets. Does not shrink
 144   void resize(size_t Size) { Map.resize(Size); }
 145
 146   void clear() {
 147     Map.clear();
 148     MDMap.reset();
 149   }
 150
 151   /// Return 1 if the specified key is in the map, 0 otherwise.
 152   size_type count(const KeyT &Val) const {
 153     return Map.find_as(Val) == Map.end() ? 0 : 1;
 154   }
 155
 156   iterator find(const KeyT &Val) {
 157     return iterator(Map.find_as(Val));
 158   }
 159   const_iterator find(const KeyT &Val) const {
 160     return const_iterator(Map.find_as(Val));
 161   }
 162
 163   /// lookup - Return the entry for the specified key, or a default
 164   /// constructed value if no such entry exists.
 165   ValueT lookup(const KeyT &Val) const {
 166     typename MapT::const_iterator I = Map.find_as(Val);
 167     return I != Map.end() ? I->second : ValueT();
 168   }
 169
 170   // Inserts key,value pair into the map if the key isn't already in the map.
 171   // If the key is already in the map, it returns false and doesn't update the
 172   // value.
 173   std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
 174     auto MapResult = Map.insert(std::make_pair(Wrap(KV.first), KV.second));
 175     return std::make_pair(iterator(MapResult.first), MapResult.second);
 176   }
 177
 178   std::pair<iterator, bool> insert(std::pair<KeyT, ValueT> &&KV) {
 179     auto MapResult =
 180         Map.insert(std::make_pair(Wrap(KV.first), std::move(KV.second)));
 181     return std::make_pair(iterator(MapResult.first), MapResult.second);
 182   }
 183
 184   /// insert - Range insertion of pairs.
 185   template<typename InputIt>
 186   void insert(InputIt I, InputIt E) {
 187     for (; I != E; ++I)
 188       insert(*I);
 189   }
 190
 191   bool erase(const KeyT &Val) {
 192     typename MapT::iterator I = Map.find_as(Val);
 193     if (I == Map.end())
 194       return false;
 195
 196     Map.erase(I);
 197     return true;
 198   }
 199   void erase(iterator I) {
 200     return Map.erase(I.base());
 201   }
 202
 203   value_type& FindAndConstruct(const KeyT &Key) {
 204     return Map.FindAndConstruct(Wrap(Key));
 205   }
 206
 207   ValueT &operator[](const KeyT &Key) {
 208     return Map[Wrap(Key)];
 209   }
 210
 211   /// isPointerIntoBucketsArray - Return true if the specified pointer points
 212   /// somewhere into the ValueMap's array of buckets (i.e. either to a key or
 213   /// value in the ValueMap).
 214   bool isPointerIntoBucketsArray(const void *Ptr) const {
 215     return Map.isPointerIntoBucketsArray(Ptr);
 216   }
 217
 218   /// getPointerIntoBucketsArray() - Return an opaque pointer into the buckets
 219   /// array.  In conjunction with the previous method, this can be used to
 220   /// determine whether an insertion caused the ValueMap to reallocate.
 221   const void *getPointerIntoBucketsArray() const {
 222     return Map.getPointerIntoBucketsArray();
 223   }
 224
 225 private:
 226   // Takes a key being looked up in the map and wraps it into a
 227   // ValueMapCallbackVH, the actual key type of the map.  We use a helper
 228   // function because ValueMapCVH is constructed with a second parameter.
 229   ValueMapCVH Wrap(KeyT key) const {
 230     // The only way the resulting CallbackVH could try to modify *this (making
 231     // the const_cast incorrect) is if it gets inserted into the map.  But then
 232     // this function must have been called from a non-const method, making the
 233     // const_cast ok.
 234     return ValueMapCVH(key, const_cast<ValueMap*>(this));
 235   }
 236 };
 237
 238 // This CallbackVH updates its ValueMap when the contained Value changes,
 239 // according to the user's preferences expressed through the Config object.
 240 template <typename KeyT, typename ValueT, typename Config>
 241 class ValueMapCallbackVH final : public CallbackVH {
 242   friend class ValueMap<KeyT, ValueT, Config>;
 243   friend struct DenseMapInfo<ValueMapCallbackVH>;
 244
 245   using ValueMapT = ValueMap<KeyT, ValueT, Config>;
 246   using KeySansPointerT = typename std::remove_pointer<KeyT>::type;
 247
 248   ValueMapT *Map;
 249
 250   ValueMapCallbackVH(KeyT Key, ValueMapT *Map)
 251       : CallbackVH(const_cast<Value*>(static_cast<const Value*>(Key))),
 252         Map(Map) {}
 253
 254   // Private constructor used to create empty/tombstone DenseMap keys.
 255   ValueMapCallbackVH(Value *V) : CallbackVH(V), Map(nullptr) {}
 256
 257 public:
 258   KeyT Unwrap() const { return cast_or_null<KeySansPointerT>(getValPtr()); }
 259
 260   void deleted() override {
 261     // Make a copy that won't get changed even when *this is destroyed.
 262     ValueMapCallbackVH Copy(*this);
 263     typename Config::mutex_type *M = Config::getMutex(Copy.Map->Data);
 264     std::unique_lock<typename Config::mutex_type> Guard;
 265     if (M)
 266       Guard = std::unique_lock<typename Config::mutex_type>(*M);
 267     Config::onDelete(Copy.Map->Data, Copy.Unwrap());  // May destroy *this.
 268     Copy.Map->Map.erase(Copy);  // Definitely destroys *this.
 269   }
 270
 271   void allUsesReplacedWith(Value *new_key) override {
 272     assert(isa<KeySansPointerT>(new_key) &&
 273            "Invalid RAUW on key of ValueMap<>");
 274     // Make a copy that won't get changed even when *this is destroyed.
 275     ValueMapCallbackVH Copy(*this);
 276     typename Config::mutex_type *M = Config::getMutex(Copy.Map->Data);
 277     std::unique_lock<typename Config::mutex_type> Guard;
 278     if (M)
 279       Guard = std::unique_lock<typename Config::mutex_type>(*M);
 280
 281     KeyT typed_new_key = cast<KeySansPointerT>(new_key);
 282     // Can destroy *this:
 283     Config::onRAUW(Copy.Map->Data, Copy.Unwrap(), typed_new_key);
 284     if (Config::FollowRAUW) {
 285       typename ValueMapT::MapT::iterator I = Copy.Map->Map.find(Copy);
 286       // I could == Copy.Map->Map.end() if the onRAUW callback already
 287       // removed the old mapping.
 288       if (I != Copy.Map->Map.end()) {
 289         ValueT Target(std::move(I->second));
 290         Copy.Map->Map.erase(I);  // Definitely destroys *this.
 291         Copy.Map->insert(std::make_pair(typed_new_key, std::move(Target)));
 292       }
 293     }
 294   }
 295 };
 296
 297 template<typename KeyT, typename ValueT, typename Config>
 298 struct DenseMapInfo<ValueMapCallbackVH<KeyT, ValueT, Config>> {
 299   using VH = ValueMapCallbackVH<KeyT, ValueT, Config>;
 300
 301   static inline VH getEmptyKey() {
 302     return VH(DenseMapInfo<Value *>::getEmptyKey());
 303   }
 304
 305   static inline VH getTombstoneKey() {
 306     return VH(DenseMapInfo<Value *>::getTombstoneKey());
 307   }
 308
 309   static unsigned getHashValue(const VH &Val) {
 310     return DenseMapInfo<KeyT>::getHashValue(Val.Unwrap());
 311   }
 312
 313   static unsigned getHashValue(const KeyT &Val) {
 314     return DenseMapInfo<KeyT>::getHashValue(Val);
 315   }
 316
 317   static bool isEqual(const VH &LHS, const VH &RHS) {
 318     return LHS == RHS;
 319   }
 320
 321   static bool isEqual(const KeyT &LHS, const VH &RHS) {
 322     return LHS == RHS.getValPtr();
 323   }
 324 };
 325
 326 template<typename DenseMapT, typename KeyT>
 327 class ValueMapIterator :
 328     public std::iterator<std::forward_iterator_tag,
 329                          std::pair<KeyT, typename DenseMapT::mapped_type>,
 330                          ptrdiff_t> {
 331   using BaseT = typename DenseMapT::iterator;
 332   using ValueT = typename DenseMapT::mapped_type;
 333
 334   BaseT I;
 335
 336 public:
 337   ValueMapIterator() : I() {}
 338   ValueMapIterator(BaseT I) : I(I) {}
 339
 340   BaseT base() const { return I; }
 341
 342   struct ValueTypeProxy {
 343     const KeyT first;
 344     ValueT& second;
 345
 346     ValueTypeProxy *operator->() { return this; }
 347
 348     operator std::pair<KeyT, ValueT>() const {
 349       return std::make_pair(first, second);
 350     }
 351   };
 352
 353   ValueTypeProxy operator*() const {
 354     ValueTypeProxy Result = {I->first.Unwrap(), I->second};
 355     return Result;
 356   }
 357
 358   ValueTypeProxy operator->() const {
 359     return operator*();
 360   }
 361
 362   bool operator==(const ValueMapIterator &RHS) const {
 363     return I == RHS.I;
 364   }
 365   bool operator!=(const ValueMapIterator &RHS) const {
 366     return I != RHS.I;
 367   }
 368
 369   inline ValueMapIterator& operator++() {  // Preincrement
 370     ++I;
 371     return *this;
 372   }
 373   ValueMapIterator operator++(int) {  // Postincrement
 374     ValueMapIterator tmp = *this; ++*this; return tmp;
 375   }
 376 };
 377
 378 template<typename DenseMapT, typename KeyT>
 379 class ValueMapConstIterator :
 380     public std::iterator<std::forward_iterator_tag,
 381                          std::pair<KeyT, typename DenseMapT::mapped_type>,
 382                          ptrdiff_t> {
 383   using BaseT = typename DenseMapT::const_iterator;
 384   using ValueT = typename DenseMapT::mapped_type;
 385
 386   BaseT I;
 387
 388 public:
 389   ValueMapConstIterator() : I() {}
 390   ValueMapConstIterator(BaseT I) : I(I) {}
 391   ValueMapConstIterator(ValueMapIterator<DenseMapT, KeyT> Other)
 392     : I(Other.base()) {}
 393
 394   BaseT base() const { return I; }
 395
 396   struct ValueTypeProxy {
 397     const KeyT first;
 398     const ValueT& second;
 399     ValueTypeProxy *operator->() { return this; }
 400     operator std::pair<KeyT, ValueT>() const {
 401       return std::make_pair(first, second);
 402     }
 403   };
 404
 405   ValueTypeProxy operator*() const {
 406     ValueTypeProxy Result = {I->first.Unwrap(), I->second};
 407     return Result;
 408   }
 409
 410   ValueTypeProxy operator->() const {
 411     return operator*();
 412   }
 413
 414   bool operator==(const ValueMapConstIterator &RHS) const {
 415     return I == RHS.I;
 416   }
 417   bool operator!=(const ValueMapConstIterator &RHS) const {
 418     return I != RHS.I;
 419   }
 420
 421   inline ValueMapConstIterator& operator++() {  // Preincrement
 422     ++I;
 423     return *this;
 424   }
 425   ValueMapConstIterator operator++(int) {  // Postincrement
 426     ValueMapConstIterator tmp = *this; ++*this; return tmp;
 427   }
 428 };
 429
 430 } // end namespace llvm
 431
 432 #endif // LLVM_IR_VALUEMAP_H