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42e4bdf257
contents of the set were small, deallocate and shrink the set. This avoids having us to memset as much data, significantly speeding up some pathological cases. For example, this speeds up the verifier from 0.3899s to 0.0763 (5.1x) on the testcase from PR1432 in a release build. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40837 91177308-0d34-0410-b5e6-96231b3b80d8
395 lines
12 KiB
C++
395 lines
12 KiB
C++
//===- llvm/ADT/DenseMap.h - Dense probed hash table ------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by Chris Lattner and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the DenseMap class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_DENSEMAP_H
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#define LLVM_ADT_DENSEMAP_H
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#include "llvm/Support/DataTypes.h"
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#include "llvm/Support/MathExtras.h"
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#include <cassert>
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#include <utility>
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namespace llvm {
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template<typename T>
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struct DenseMapKeyInfo {
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//static inline T getEmptyKey();
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//static inline T getTombstoneKey();
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//static unsigned getHashValue(const T &Val);
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//static bool isPod()
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};
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// Provide DenseMapKeyInfo for all pointers.
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template<typename T>
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struct DenseMapKeyInfo<T*> {
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static inline T* getEmptyKey() { return (T*)-1; }
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static inline T* getTombstoneKey() { return (T*)-2; }
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static unsigned getHashValue(const T *PtrVal) {
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return (unsigned)((uintptr_t)PtrVal >> 4) ^
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(unsigned)((uintptr_t)PtrVal >> 9);
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}
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static bool isPod() { return true; }
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};
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template<typename KeyT, typename ValueT,
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typename KeyInfoT = DenseMapKeyInfo<KeyT> >
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class DenseMapIterator;
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template<typename KeyT, typename ValueT,
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typename KeyInfoT = DenseMapKeyInfo<KeyT> >
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class DenseMapConstIterator;
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template<typename KeyT, typename ValueT,
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typename KeyInfoT = DenseMapKeyInfo<KeyT> >
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class DenseMap {
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typedef std::pair<KeyT, ValueT> BucketT;
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unsigned NumBuckets;
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BucketT *Buckets;
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unsigned NumEntries;
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unsigned NumTombstones;
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DenseMap(const DenseMap &); // not implemented.
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public:
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explicit DenseMap(unsigned NumInitBuckets = 64) {
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init(NumInitBuckets);
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}
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~DenseMap() {
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const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
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for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
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if (P->first != EmptyKey && P->first != TombstoneKey)
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P->second.~ValueT();
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P->first.~KeyT();
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}
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delete[] (char*)Buckets;
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}
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typedef DenseMapIterator<KeyT, ValueT, KeyInfoT> iterator;
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typedef DenseMapConstIterator<KeyT, ValueT, KeyInfoT> const_iterator;
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inline iterator begin() {
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return iterator(Buckets, Buckets+NumBuckets);
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}
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inline iterator end() {
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return iterator(Buckets+NumBuckets, Buckets+NumBuckets);
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}
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inline const_iterator begin() const {
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return const_iterator(Buckets, Buckets+NumBuckets);
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}
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inline const_iterator end() const {
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return const_iterator(Buckets+NumBuckets, Buckets+NumBuckets);
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}
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bool empty() const { return NumEntries == 0; }
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unsigned size() const { return NumEntries; }
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void clear() {
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// If the capacity of the array is huge, and the # elements used is small,
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// shrink the array.
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if (NumEntries * 4 < NumBuckets && NumBuckets > 64) {
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shrink_and_clear();
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return;
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}
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const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
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for (BucketT *P = Buckets, *E = Buckets+NumBuckets; P != E; ++P) {
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if (P->first != EmptyKey && P->first != TombstoneKey) {
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P->first = EmptyKey;
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P->second.~ValueT();
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--NumEntries;
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}
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}
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assert(NumEntries == 0 && "Node count imbalance!");
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NumTombstones = 0;
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}
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/// count - Return true if the specified key is in the map.
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bool count(const KeyT &Val) const {
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BucketT *TheBucket;
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return LookupBucketFor(Val, TheBucket);
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}
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iterator find(const KeyT &Val) {
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BucketT *TheBucket;
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if (LookupBucketFor(Val, TheBucket))
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return iterator(TheBucket, Buckets+NumBuckets);
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return end();
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}
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const_iterator find(const KeyT &Val) const {
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BucketT *TheBucket;
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if (LookupBucketFor(Val, TheBucket))
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return const_iterator(TheBucket, Buckets+NumBuckets);
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return end();
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}
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bool insert(const std::pair<KeyT, ValueT> &KV) {
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BucketT *TheBucket;
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if (LookupBucketFor(KV.first, TheBucket))
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return false; // Already in map.
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// Otherwise, insert the new element.
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InsertIntoBucket(KV.first, KV.second, TheBucket);
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return true;
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}
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bool erase(const KeyT &Val) {
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BucketT *TheBucket;
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if (!LookupBucketFor(Val, TheBucket))
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return false; // not in map.
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TheBucket->second.~ValueT();
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TheBucket->first = getTombstoneKey();
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--NumEntries;
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++NumTombstones;
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return true;
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}
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bool erase(iterator I) {
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BucketT *TheBucket = &*I;
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TheBucket->second.~ValueT();
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TheBucket->first = getTombstoneKey();
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--NumEntries;
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++NumTombstones;
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return true;
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}
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ValueT &operator[](const KeyT &Key) {
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BucketT *TheBucket;
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if (LookupBucketFor(Key, TheBucket))
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return TheBucket->second;
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return InsertIntoBucket(Key, ValueT(), TheBucket)->second;
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}
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private:
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BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value,
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BucketT *TheBucket) {
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// If the load of the hash table is more than 3/4, or if fewer than 1/8 of
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// the buckets are empty (meaning that many are filled with tombstones),
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// grow the table.
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//
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// The later case is tricky. For example, if we had one empty bucket with
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// tons of tombstones, failing lookups (e.g. for insertion) would have to
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// probe almost the entire table until it found the empty bucket. If the
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// table completely filled with tombstones, no lookup would ever succeed,
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// causing infinite loops in lookup.
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if (NumEntries*4 >= NumBuckets*3 ||
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NumBuckets-(NumEntries+NumTombstones) < NumBuckets/8) {
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this->grow();
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LookupBucketFor(Key, TheBucket);
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}
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++NumEntries;
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// If we are writing over a tombstone, remember this.
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if (TheBucket->first != getEmptyKey())
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--NumTombstones;
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TheBucket->first = Key;
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new (&TheBucket->second) ValueT(Value);
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return TheBucket;
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}
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static unsigned getHashValue(const KeyT &Val) {
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return KeyInfoT::getHashValue(Val);
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}
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static const KeyT getEmptyKey() {
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return KeyInfoT::getEmptyKey();
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}
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static const KeyT getTombstoneKey() {
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return KeyInfoT::getTombstoneKey();
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}
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/// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in
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/// FoundBucket. If the bucket contains the key and a value, this returns
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/// true, otherwise it returns a bucket with an empty marker or tombstone and
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/// returns false.
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bool LookupBucketFor(const KeyT &Val, BucketT *&FoundBucket) const {
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unsigned BucketNo = getHashValue(Val);
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unsigned ProbeAmt = 1;
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BucketT *BucketsPtr = Buckets;
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// FoundTombstone - Keep track of whether we find a tombstone while probing.
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BucketT *FoundTombstone = 0;
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const KeyT EmptyKey = getEmptyKey();
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const KeyT TombstoneKey = getTombstoneKey();
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assert(Val != EmptyKey && Val != TombstoneKey &&
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"Empty/Tombstone value shouldn't be inserted into map!");
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while (1) {
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BucketT *ThisBucket = BucketsPtr + (BucketNo & (NumBuckets-1));
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// Found Val's bucket? If so, return it.
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if (ThisBucket->first == Val) {
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FoundBucket = ThisBucket;
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return true;
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}
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// If we found an empty bucket, the key doesn't exist in the set.
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// Insert it and return the default value.
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if (ThisBucket->first == EmptyKey) {
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// If we've already seen a tombstone while probing, fill it in instead
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// of the empty bucket we eventually probed to.
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if (FoundTombstone) ThisBucket = FoundTombstone;
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FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket;
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return false;
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}
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// If this is a tombstone, remember it. If Val ends up not in the map, we
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// prefer to return it than something that would require more probing.
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if (ThisBucket->first == TombstoneKey && !FoundTombstone)
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FoundTombstone = ThisBucket; // Remember the first tombstone found.
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// Otherwise, it's a hash collision or a tombstone, continue quadratic
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// probing.
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BucketNo += ProbeAmt++;
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}
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}
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void init(unsigned InitBuckets) {
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NumEntries = 0;
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NumTombstones = 0;
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NumBuckets = InitBuckets;
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assert(InitBuckets && (InitBuckets & InitBuckets-1) == 0 &&
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"# initial buckets must be a power of two!");
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Buckets = (BucketT*)new char[sizeof(BucketT)*InitBuckets];
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// Initialize all the keys to EmptyKey.
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const KeyT EmptyKey = getEmptyKey();
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for (unsigned i = 0; i != InitBuckets; ++i)
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new (&Buckets[i].first) KeyT(EmptyKey);
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}
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void grow() {
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unsigned OldNumBuckets = NumBuckets;
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BucketT *OldBuckets = Buckets;
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// Double the number of buckets.
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NumBuckets <<= 1;
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NumTombstones = 0;
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Buckets = (BucketT*)new char[sizeof(BucketT)*NumBuckets];
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// Initialize all the keys to EmptyKey.
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const KeyT EmptyKey = getEmptyKey();
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for (unsigned i = 0, e = NumBuckets; i != e; ++i)
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new (&Buckets[i].first) KeyT(EmptyKey);
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// Insert all the old elements.
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const KeyT TombstoneKey = getTombstoneKey();
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for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) {
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if (B->first != EmptyKey && B->first != TombstoneKey) {
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// Insert the key/value into the new table.
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BucketT *DestBucket;
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bool FoundVal = LookupBucketFor(B->first, DestBucket);
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FoundVal = FoundVal; // silence warning.
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assert(!FoundVal && "Key already in new map?");
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DestBucket->first = B->first;
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new (&DestBucket->second) ValueT(B->second);
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// Free the value.
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B->second.~ValueT();
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}
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B->first.~KeyT();
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}
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// Free the old table.
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delete[] (char*)OldBuckets;
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}
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void shrink_and_clear() {
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unsigned OldNumBuckets = NumBuckets;
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BucketT *OldBuckets = Buckets;
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// Reduce the number of buckets.
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NumBuckets = NumEntries > 32 ? 1 << (Log2_32_Ceil(NumEntries) + 1)
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: 64;
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NumTombstones = 0;
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Buckets = (BucketT*)new char[sizeof(BucketT)*NumBuckets];
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// Initialize all the keys to EmptyKey.
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const KeyT EmptyKey = getEmptyKey();
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for (unsigned i = 0, e = NumBuckets; i != e; ++i)
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new (&Buckets[i].first) KeyT(EmptyKey);
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// Free the old buckets.
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const KeyT TombstoneKey = getTombstoneKey();
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for (BucketT *B = OldBuckets, *E = OldBuckets+OldNumBuckets; B != E; ++B) {
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if (B->first != EmptyKey && B->first != TombstoneKey) {
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// Free the value.
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B->second.~ValueT();
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}
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B->first.~KeyT();
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}
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// Free the old table.
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delete[] (char*)OldBuckets;
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NumEntries = 0;
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}
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};
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template<typename KeyT, typename ValueT, typename KeyInfoT>
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class DenseMapIterator {
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typedef std::pair<KeyT, ValueT> BucketT;
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protected:
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const BucketT *Ptr, *End;
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public:
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DenseMapIterator(const BucketT *Pos, const BucketT *E) : Ptr(Pos), End(E) {
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AdvancePastEmptyBuckets();
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}
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std::pair<KeyT, ValueT> &operator*() const {
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return *const_cast<BucketT*>(Ptr);
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}
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std::pair<KeyT, ValueT> *operator->() const {
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return const_cast<BucketT*>(Ptr);
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}
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bool operator==(const DenseMapIterator &RHS) const {
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return Ptr == RHS.Ptr;
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}
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bool operator!=(const DenseMapIterator &RHS) const {
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return Ptr != RHS.Ptr;
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}
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inline DenseMapIterator& operator++() { // Preincrement
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++Ptr;
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AdvancePastEmptyBuckets();
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return *this;
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}
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DenseMapIterator operator++(int) { // Postincrement
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DenseMapIterator tmp = *this; ++*this; return tmp;
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}
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private:
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void AdvancePastEmptyBuckets() {
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const KeyT Empty = KeyInfoT::getEmptyKey();
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const KeyT Tombstone = KeyInfoT::getTombstoneKey();
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while (Ptr != End && (Ptr->first == Empty || Ptr->first == Tombstone))
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++Ptr;
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}
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};
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template<typename KeyT, typename ValueT, typename KeyInfoT>
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class DenseMapConstIterator : public DenseMapIterator<KeyT, ValueT, KeyInfoT> {
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public:
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DenseMapConstIterator(const std::pair<KeyT, ValueT> *Pos,
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const std::pair<KeyT, ValueT> *E)
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: DenseMapIterator<KeyT, ValueT, KeyInfoT>(Pos, E) {
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}
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const std::pair<KeyT, ValueT> &operator*() const {
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return *this->Ptr;
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}
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const std::pair<KeyT, ValueT> *operator->() const {
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return this->Ptr;
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}
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};
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} // end namespace llvm
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#endif
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