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//===- HashTable.h - PDB Hash Table -----------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_DEBUGINFO_PDB_NATIVE_HASHTABLE_H
#define LLVM_DEBUGINFO_PDB_NATIVE_HASHTABLE_H
#include "llvm/ADT/SparseBitVector.h"
#include "llvm/ADT/iterator.h"
#include "llvm/DebugInfo/PDB/Native/RawError.h"
#include "llvm/Support/BinaryStreamReader.h"
#include "llvm/Support/BinaryStreamWriter.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/Error.h"
#include <cstdint>
#include <iterator>
#include <utility>
#include <vector>
namespace llvm {
namespace pdb {
Error readSparseBitVector(BinaryStreamReader &Stream, SparseBitVector<> &V);
Error writeSparseBitVector(BinaryStreamWriter &Writer, SparseBitVector<> &Vec);
template <typename ValueT> class HashTable;
template <typename ValueT>
class HashTableIterator
: public iterator_facade_base<HashTableIterator<ValueT>,
std::forward_iterator_tag,
const std::pair<uint32_t, ValueT>> {
using BaseT = typename HashTableIterator::iterator_facade_base;
friend HashTable<ValueT>;
HashTableIterator(const HashTable<ValueT> &Map, uint32_t Index,
bool IsEnd)
: Map(&Map), Index(Index), IsEnd(IsEnd) {}
public:
HashTableIterator(const HashTable<ValueT> &Map) : Map(&Map) {
int I = Map.Present.find_first();
if (I == -1) {
Index = 0;
IsEnd = true;
} else {
Index = static_cast<uint32_t>(I);
IsEnd = false;
}
}
HashTableIterator(const HashTableIterator &R) = default;
HashTableIterator &operator=(const HashTableIterator &R) {
Map = R.Map;
return *this;
}
bool operator==(const HashTableIterator &R) const {
if (IsEnd && R.IsEnd)
return true;
if (IsEnd != R.IsEnd)
return false;
return (Map == R.Map) && (Index == R.Index);
}
const std::pair<uint32_t, ValueT> &operator*() const {
assert(Map->Present.test(Index));
return Map->Buckets[Index];
}
// Implement postfix op++ in terms of prefix op++ by using the superclass
// implementation.
using BaseT::operator++;
HashTableIterator &operator++() {
while (Index < Map->Buckets.size()) {
++Index;
if (Map->Present.test(Index))
return *this;
}
IsEnd = true;
return *this;
}
private:
bool isEnd() const { return IsEnd; }
uint32_t index() const { return Index; }
const HashTable<ValueT> *Map;
uint32_t Index;
bool IsEnd;
};
template <typename ValueT>
class HashTable {
struct Header {
support::ulittle32_t Size;
support::ulittle32_t Capacity;
};
using BucketList = std::vector<std::pair<uint32_t, ValueT>>;
public:
using const_iterator = HashTableIterator<ValueT>;
friend const_iterator;
HashTable() { Buckets.resize(8); }
explicit HashTable(uint32_t Capacity) {
Buckets.resize(Capacity);
}
Error load(BinaryStreamReader &Stream) {
const Header *H;
if (auto EC = Stream.readObject(H))
return EC;
if (H->Capacity == 0)
return make_error<RawError>(raw_error_code::corrupt_file,
"Invalid Hash Table Capacity");
if (H->Size > maxLoad(H->Capacity))
return make_error<RawError>(raw_error_code::corrupt_file,
"Invalid Hash Table Size");
Buckets.resize(H->Capacity);
if (auto EC = readSparseBitVector(Stream, Present))
return EC;
if (Present.count() != H->Size)
return make_error<RawError>(raw_error_code::corrupt_file,
"Present bit vector does not match size!");
if (auto EC = readSparseBitVector(Stream, Deleted))
return EC;
if (Present.intersects(Deleted))
return make_error<RawError>(raw_error_code::corrupt_file,
"Present bit vector intersects deleted!");
for (uint32_t P : Present) {
if (auto EC = Stream.readInteger(Buckets[P].first))
return EC;
const ValueT *Value;
if (auto EC = Stream.readObject(Value))
return EC;
Buckets[P].second = *Value;
}
return Error::success();
}
uint32_t calculateSerializedLength() const {
uint32_t Size = sizeof(Header);
constexpr int BitsPerWord = 8 * sizeof(uint32_t);
int NumBitsP = Present.find_last() + 1;
int NumBitsD = Deleted.find_last() + 1;
uint32_t NumWordsP = alignTo(NumBitsP, BitsPerWord) / BitsPerWord;
uint32_t NumWordsD = alignTo(NumBitsD, BitsPerWord) / BitsPerWord;
// Present bit set number of words (4 bytes), followed by that many actual
// words (4 bytes each).
Size += sizeof(uint32_t);
Size += NumWordsP * sizeof(uint32_t);
// Deleted bit set number of words (4 bytes), followed by that many actual
// words (4 bytes each).
Size += sizeof(uint32_t);
Size += NumWordsD * sizeof(uint32_t);
// One (Key, ValueT) pair for each entry Present.
Size += (sizeof(uint32_t) + sizeof(ValueT)) * size();
return Size;
}
Error commit(BinaryStreamWriter &Writer) const {
Header H;
H.Size = size();
H.Capacity = capacity();
if (auto EC = Writer.writeObject(H))
return EC;
if (auto EC = writeSparseBitVector(Writer, Present))
return EC;
if (auto EC = writeSparseBitVector(Writer, Deleted))
return EC;
for (const auto &Entry : *this) {
if (auto EC = Writer.writeInteger(Entry.first))
return EC;
if (auto EC = Writer.writeObject(Entry.second))
return EC;
}
return Error::success();
}
void clear() {
Buckets.resize(8);
Present.clear();
Deleted.clear();
}
bool empty() const { return size() == 0; }
uint32_t capacity() const { return Buckets.size(); }
uint32_t size() const { return Present.count(); }
const_iterator begin() const { return const_iterator(*this); }
const_iterator end() const { return const_iterator(*this, 0, true); }
/// Find the entry whose key has the specified hash value, using the specified
/// traits defining hash function and equality.
template <typename Key, typename TraitsT>
const_iterator find_as(const Key &K, TraitsT &Traits) const {
uint32_t H = Traits.hashLookupKey(K) % capacity();
uint32_t I = H;
std::optional<uint32_t> FirstUnused;
do {
if (isPresent(I)) {
if (Traits.storageKeyToLookupKey(Buckets[I].first) == K)
return const_iterator(*this, I, false);
} else {
if (!FirstUnused)
FirstUnused = I;
// Insertion occurs via linear probing from the slot hint, and will be
// inserted at the first empty / deleted location. Therefore, if we are
// probing and find a location that is neither present nor deleted, then
// nothing must have EVER been inserted at this location, and thus it is
// not possible for a matching value to occur later.
if (!isDeleted(I))
break;
}
I = (I + 1) % capacity();
} while (I != H);
// The only way FirstUnused would not be set is if every single entry in the
// table were Present. But this would violate the load factor constraints
// that we impose, so it should never happen.
assert(FirstUnused);
return const_iterator(*this, *FirstUnused, true);
}
/// Set the entry using a key type that the specified Traits can convert
/// from a real key to an internal key.
template <typename Key, typename TraitsT>
bool set_as(const Key &K, ValueT V, TraitsT &Traits) {
return set_as_internal(K, std::move(V), Traits, std::nullopt);
}
template <typename Key, typename TraitsT>
ValueT get(const Key &K, TraitsT &Traits) const {
auto Iter = find_as(K, Traits);
assert(Iter != end());
return (*Iter).second;
}
protected:
bool isPresent(uint32_t K) const { return Present.test(K); }
bool isDeleted(uint32_t K) const { return Deleted.test(K); }
BucketList Buckets;
mutable SparseBitVector<> Present;
mutable SparseBitVector<> Deleted;
private:
/// Set the entry using a key type that the specified Traits can convert
/// from a real key to an internal key.
template <typename Key, typename TraitsT>
bool set_as_internal(const Key &K, ValueT V, TraitsT &Traits,
std::optional<uint32_t> InternalKey) {
auto Entry = find_as(K, Traits);
if (Entry != end()) {
assert(isPresent(Entry.index()));
assert(Traits.storageKeyToLookupKey(Buckets[Entry.index()].first) == K);
// We're updating, no need to do anything special.
Buckets[Entry.index()].second = V;
return false;
}
auto &B = Buckets[Entry.index()];
assert(!isPresent(Entry.index()));
assert(Entry.isEnd());
B.first = InternalKey ? *InternalKey : Traits.lookupKeyToStorageKey(K);
B.second = V;
Present.set(Entry.index());
Deleted.reset(Entry.index());
grow(Traits);
assert((find_as(K, Traits)) != end());
return true;
}
static uint32_t maxLoad(uint32_t capacity) { return capacity * 2 / 3 + 1; }
template <typename TraitsT>
void grow(TraitsT &Traits) {
uint32_t S = size();
uint32_t MaxLoad = maxLoad(capacity());
if (S < maxLoad(capacity()))
return;
assert(capacity() != UINT32_MAX && "Can't grow Hash table!");
uint32_t NewCapacity = (capacity() <= INT32_MAX) ? MaxLoad * 2 : UINT32_MAX;
// Growing requires rebuilding the table and re-hashing every item. Make a
// copy with a larger capacity, insert everything into the copy, then swap
// it in.
HashTable NewMap(NewCapacity);
for (auto I : Present) {
auto LookupKey = Traits.storageKeyToLookupKey(Buckets[I].first);
NewMap.set_as_internal(LookupKey, Buckets[I].second, Traits,
Buckets[I].first);
}
Buckets.swap(NewMap.Buckets);
std::swap(Present, NewMap.Present);
std::swap(Deleted, NewMap.Deleted);
assert(capacity() == NewCapacity);
assert(size() == S);
}
};
} // end namespace pdb
} // end namespace llvm
#endif // LLVM_DEBUGINFO_PDB_NATIVE_HASHTABLE_H
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