include/llvm/IR/ValueMap.h

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