X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FADT%2FDenseMap.h;h=83edd640e33493125f6539b91125bbce70170b6f;hb=a727d5502c8e23c090da658bf14c5ebc1169a070;hp=5fcdfae9dea71235f54e14e1b8ecc9fee3cda8ac;hpb=4d0d864be3d9a698c4edfe36961a22126f041298;p=oota-llvm.git

diff --git a/include/llvm/ADT/DenseMap.h b/include/llvm/ADT/DenseMap.h
index 5fcdfae9dea..83edd640e33 100644
--- a/include/llvm/ADT/DenseMap.h
+++ b/include/llvm/ADT/DenseMap.h
@@ -1,61 +1,355 @@
-//===- DenseMap.h - A dense map implmentation -------------------*- C++ -*-===//
-// 
+//===- llvm/ADT/DenseMap.h - Dense probed hash table ------------*- C++ -*-===//
+//
 //                     The LLVM Compiler Infrastructure
 //
-// This file was developed by the LLVM research group and is distributed under
+// This file was developed by Chris Lattner and is distributed under
 // the University of Illinois Open Source License. See LICENSE.TXT for details.
-// 
+//
 //===----------------------------------------------------------------------===//
 //
-// This file implements a dense map. A dense map template takes two
-// types. The first is the mapped type and the second is a functor
-// that maps its argument to a size_t. On instanciation a "null" value
-// can be provided to be used as a "does not exist" indicator in the
-// map. A member function grow() is provided that given the value of
-// the maximally indexed key (the argument of the functor) makes sure
-// the map has enough space for it.
+// This file defines the DenseMap class.
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef SUPPORT_DENSEMAP_H
-#define SUPPORT_DENSEMAP_H
+#ifndef LLVM_ADT_DENSEMAP_H
+#define LLVM_ADT_DENSEMAP_H
 
-#include <vector>
+#include "llvm/Support/DataTypes.h"
+#include <cassert>
+#include <utility>
 
 namespace llvm {
+  
+template<typename T>
+struct DenseMapKeyInfo {
+  //static inline T getEmptyKey();
+  //static inline T getTombstoneKey();
+  //static unsigned getHashValue(const T &Val);
+  //static bool isPod()
+};
 
-template <typename T, typename ToIndexT>
-class DenseMap {
-    typedef typename ToIndexT::argument_type IndexT;
-    typedef std::vector<T> StorageT;
-    StorageT storage_;
-    T nullVal_;
-    ToIndexT toIndex_;
+// Provide DenseMapKeyInfo for all pointers.
+template<typename T>
+struct DenseMapKeyInfo<T*> {
+  static inline T* getEmptyKey() { return (T*)-1; }
+  static inline T* getTombstoneKey() { return (T*)-2; }
+  static unsigned getHashValue(const T *PtrVal) {
+    return (unsigned)((uintptr_t)PtrVal >> 4) ^
+           (unsigned)((uintptr_t)PtrVal >> 9);
+  }
+  static bool isPod() { return true; }
+};
 
+template<typename KeyT, typename ValueT, 
+         typename KeyInfoT = DenseMapKeyInfo<KeyT> >
+class DenseMapIterator;
+template<typename KeyT, typename ValueT,
+         typename KeyInfoT = DenseMapKeyInfo<KeyT> >
+class DenseMapConstIterator;
+
+template<typename KeyT, typename ValueT,
+         typename KeyInfoT = DenseMapKeyInfo<KeyT> >
+class DenseMap {
+  typedef std::pair<KeyT, ValueT> BucketT;
+  unsigned NumBuckets;
+  BucketT *Buckets;
+  
+  unsigned NumEntries;
+  unsigned NumTombstones;
+  DenseMap(const DenseMap &); // not implemented.
 public:
-    DenseMap() { }
+  explicit DenseMap(unsigned NumInitBuckets = 64) {
+    init(NumInitBuckets);
+  }
+  ~DenseMap() {
+    const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
+    for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
+      if (P->first != EmptyKey && P->first != TombstoneKey)
+        P->second.~ValueT();
+      P->first.~KeyT();
+    }
+    delete[] (char*)Buckets;
+  }
+  
+  typedef DenseMapIterator<KeyT, ValueT, KeyInfoT> iterator;
+  typedef DenseMapConstIterator<KeyT, ValueT, KeyInfoT> const_iterator;
+  inline iterator begin() {
+     return iterator(Buckets, Buckets+NumBuckets);
+  }
+  inline iterator end() {
+    return iterator(Buckets+NumBuckets, Buckets+NumBuckets);
+  }
+  inline const_iterator begin() const {
+    return const_iterator(Buckets, Buckets+NumBuckets);
+  }
+  inline const_iterator end() const {
+    return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets);
+  }
+  
+  bool empty() const { return NumEntries == 0; }
+  unsigned size() const { return NumEntries; }
+  
+  void clear() {
+    const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
+    for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
+      if (P->first != EmptyKey && P->first != TombstoneKey) {
+        P->first = EmptyKey;
+        P->second.~ValueT();
+        --NumEntries;
+      }
+    }
+    assert(NumEntries == 0 && "Node count imbalance!");
+    NumTombstones = 0;
+  }
+  
+  /// count - Return true if the specified key is in the map.
+  bool count(const KeyT &Val) const {
+    BucketT *TheBucket;
+    return LookupBucketFor(Val, TheBucket);
+  }
+  
+  iterator find(const KeyT &Val) {
+    BucketT *TheBucket;
+    if (LookupBucketFor(Val, TheBucket))
+      return iterator(TheBucket, Buckets+NumBuckets);
+    return end();
+  }
+  const_iterator find(const KeyT &Val) const {
+    BucketT *TheBucket;
+    if (LookupBucketFor(Val, TheBucket))
+      return const_iterator(TheBucket, Buckets+NumBuckets);
+    return end();
+  }
+  
+  bool insert(const std::pair<KeyT, ValueT> &KV) {
+    BucketT *TheBucket;
+    if (LookupBucketFor(KV.first, TheBucket))
+      return false; // Already in map.
+    
+    // Otherwise, insert the new element.
+    InsertIntoBucket(KV.first, KV.second, TheBucket);
+    return true;
+  }
+  
+  bool erase(const KeyT &Val) {
+    BucketT *TheBucket;
+    if (!LookupBucketFor(Val, TheBucket))
+      return false; // not in map.
 
-    explicit DenseMap(const T& val) : nullVal_(val) { }
+    TheBucket->second.~ValueT();
+    TheBucket->first = getTombstoneKey();
+    --NumEntries;
+    ++NumTombstones;
+    return true;
+  }
+  bool erase(iterator I) {
+    BucketT *TheBucket = &*I;
+    TheBucket->second.~ValueT();
+    TheBucket->first = getTombstoneKey();
+    --NumEntries;
+    ++NumTombstones;
+    return true;
+  }
+  
+  ValueT &operator[](const KeyT &Key) {
+    BucketT *TheBucket;
+    if (LookupBucketFor(Key, TheBucket))
+      return TheBucket->second;
 
-    typename StorageT::reference operator[](IndexT n) {
-        assert(toIndex_(n) < storage_.size() && "index out of bounds!");
-        return storage_[toIndex_(n)];
+    return InsertIntoBucket(Key, ValueT(), TheBucket)->second;
+  }
+  
+private:
+  BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value,
+                            BucketT *TheBucket) {
+    // If the load of the hash table is more than 3/4, or if fewer than 1/8 of
+    // the buckets are empty (meaning that many are filled with tombstones),
+    // grow the table.
+    //
+    // The later case is tricky.  For example, if we had one empty bucket with
+    // tons of tombstones, failing lookups (e.g. for insertion) would have to
+    // probe almost the entire table until it found the empty bucket.  If the
+    // table completely filled with tombstones, no lookup would ever succeed,
+    // causing infinite loops in lookup.
+    if (NumEntries*4 >= NumBuckets*3 ||
+        NumBuckets-(NumEntries+NumTombstones) < NumBuckets/8) {        
+      this->grow();
+      LookupBucketFor(Key, TheBucket);
     }
+    ++NumEntries;
+    
+    // If we are writing over a tombstone, remember this.
+    if (TheBucket->first != getEmptyKey())
+      --NumTombstones;
+    
+    TheBucket->first = Key;
+    new (&TheBucket->second) ValueT(Value);
+    return TheBucket;
+  }
 
-    typename StorageT::const_reference operator[](IndexT n) const {
-        assert(toIndex_(n) < storage_.size() && "index out of bounds!");
-        return storage_[toIndex_(n)];
+  static unsigned getHashValue(const KeyT &Val) {
+    return KeyInfoT::getHashValue(Val);
+  }
+  static const KeyT getEmptyKey() {
+    return KeyInfoT::getEmptyKey();
+  }
+  static const KeyT getTombstoneKey() {
+    return KeyInfoT::getTombstoneKey();
+  }
+  
+  /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in
+  /// FoundBucket.  If the bucket contains the key and a value, this returns
+  /// true, otherwise it returns a bucket with an empty marker or tombstone and
+  /// returns false.
+  bool LookupBucketFor(const KeyT &Val, BucketT *&FoundBucket) const {
+    unsigned BucketNo = getHashValue(Val);
+    unsigned ProbeAmt = 1;
+    BucketT *BucketsPtr = Buckets;
+    
+    // FoundTombstone - Keep track of whether we find a tombstone while probing.
+    BucketT *FoundTombstone = 0;
+    const KeyT EmptyKey = getEmptyKey();
+    const KeyT TombstoneKey = getTombstoneKey();
+    assert(Val != EmptyKey && Val != TombstoneKey &&
+           "Empty/Tombstone value shouldn't be inserted into map!");
+      
+    while (1) {
+      BucketT *ThisBucket = BucketsPtr + (BucketNo & (NumBuckets-1));
+      // Found Val's bucket?  If so, return it.
+      if (ThisBucket->first == Val) {
+        FoundBucket = ThisBucket;
+        return true;
+      }
+      
+      // If we found an empty bucket, the key doesn't exist in the set.
+      // Insert it and return the default value.
+      if (ThisBucket->first == EmptyKey) {
+        // If we've already seen a tombstone while probing, fill it in instead
+        // of the empty bucket we eventually probed to.
+        if (FoundTombstone) ThisBucket = FoundTombstone;
+        FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket;
+        return false;
+      }
+      
+      // If this is a tombstone, remember it.  If Val ends up not in the map, we
+      // prefer to return it than something that would require more probing.
+      if (ThisBucket->first == TombstoneKey && !FoundTombstone)
+        FoundTombstone = ThisBucket;  // Remember the first tombstone found.
+      
+      // Otherwise, it's a hash collision or a tombstone, continue quadratic
+      // probing.
+      BucketNo += ProbeAmt++;
     }
+  }
 
-    void clear() {
-        storage_.assign(storage_.size(), nullVal_);
-    }
+  void init(unsigned InitBuckets) {
+    NumEntries = 0;
+    NumTombstones = 0;
+    NumBuckets = InitBuckets;
+    assert(InitBuckets && (InitBuckets & InitBuckets-1) == 0 &&
+           "# initial buckets must be a power of two!");
+    Buckets = (BucketT*)new char[sizeof(BucketT)*InitBuckets];
+    // Initialize all the keys to EmptyKey.
+    const KeyT EmptyKey = getEmptyKey();
+    for (unsigned i = 0; i != InitBuckets; ++i)
+      new (&Buckets[i].first) KeyT(EmptyKey);
+  }
+  
+  void grow() {
+    unsigned OldNumBuckets = NumBuckets;
+    BucketT *OldBuckets = Buckets;
+    
+    // Double the number of buckets.
+    NumBuckets <<= 1;
+    NumTombstones = 0;
+    Buckets = (BucketT*)new char[sizeof(BucketT)*NumBuckets];
+
+    // Initialize all the keys to EmptyKey.
+    const KeyT EmptyKey = getEmptyKey();
+    for (unsigned i = 0, e = NumBuckets; i != e; ++i)
+      new (&Buckets[i].first) KeyT(EmptyKey);
 
-    void grow(IndexT n) {
-        storage_.resize(toIndex_(n) + 1, nullVal_);
+    // Insert all the old elements.
+    const KeyT TombstoneKey = getTombstoneKey();
+    for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) {
+      if (B->first != EmptyKey && B->first != TombstoneKey) {
+        // Insert the key/value into the new table.
+        BucketT *DestBucket;
+        bool FoundVal = LookupBucketFor(B->first, DestBucket);
+        FoundVal = FoundVal; // silence warning.
+        assert(!FoundVal && "Key already in new map?");
+        DestBucket->first = B->first;
+        new (&DestBucket->second) ValueT(B->second);
+        
+        // Free the value.
+        B->second.~ValueT();
+      }
+      B->first.~KeyT();
     }
+    
+    // Free the old table.
+    delete[] (char*)OldBuckets;
+  }
+};
+
+template<typename KeyT, typename ValueT, typename KeyInfoT>
+class DenseMapIterator {
+  typedef std::pair<KeyT, ValueT> BucketT;
+protected:
+  const BucketT *Ptr, *End;
+public:
+  DenseMapIterator(const BucketT *Pos, const BucketT *E) : Ptr(Pos), End(E) {
+    AdvancePastEmptyBuckets();
+  }
+  
+  std::pair<KeyT, ValueT> &operator*() const {
+    return *const_cast<BucketT*>(Ptr);
+  }
+  std::pair<KeyT, ValueT> *operator->() const {
+    return const_cast<BucketT*>(Ptr);
+  }
+  
+  bool operator==(const DenseMapIterator &RHS) const {
+    return Ptr == RHS.Ptr;
+  }
+  bool operator!=(const DenseMapIterator &RHS) const {
+    return Ptr != RHS.Ptr;
+  }
+  
+  inline DenseMapIterator& operator++() {          // Preincrement
+    ++Ptr;
+    AdvancePastEmptyBuckets();
+    return *this;
+  }
+  DenseMapIterator operator++(int) {        // Postincrement
+    DenseMapIterator tmp = *this; ++*this; return tmp;
+  }
+  
+private:
+  void AdvancePastEmptyBuckets() {
+    const KeyT Empty = KeyInfoT::getEmptyKey();
+    const KeyT Tombstone = KeyInfoT::getTombstoneKey();
+
+    while (Ptr != End && (Ptr->first == Empty || Ptr->first == Tombstone))
+      ++Ptr;
+  }
+};
+
+template<typename KeyT, typename ValueT, typename KeyInfoT>
+class DenseMapConstIterator : public DenseMapIterator<KeyT, ValueT, KeyInfoT> {
+public:
+  DenseMapConstIterator(const std::pair<KeyT, ValueT> *Pos,
+                        const std::pair<KeyT, ValueT> *E)
+    : DenseMapIterator<KeyT, ValueT, KeyInfoT>(Pos, E) {
+  }
+  const std::pair<KeyT, ValueT> &operator*() const {
+    return *this->Ptr;
+  }
+  const std::pair<KeyT, ValueT> *operator->() const {
+    return this->Ptr;
+  }
 };
 
-} // End llvm namespace
+} // end namespace llvm
 
 #endif