llvm-6502/include/llvm/ADT/FoldingSet.h
Dan Gohman d6a2aab53e Add an optional optimization to FoldingSet to allow ID values to be
stored rather than recomputed on each bucket traversal.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75480 91177308-0d34-0410-b5e6-96231b3b80d8
2009-07-13 18:25:44 +00:00

476 lines
16 KiB
C++

//===-- llvm/ADT/FoldingSet.h - Uniquing Hash Set ---------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines a hash set that can be used to remove duplication of nodes
// in a graph. This code was originally created by Chris Lattner for use with
// SelectionDAGCSEMap, but was isolated to provide use across the llvm code set.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_FOLDINGSET_H
#define LLVM_ADT_FOLDINGSET_H
#include "llvm/Support/DataTypes.h"
#include "llvm/ADT/SmallVector.h"
#include <string>
#include <iterator>
namespace llvm {
class APFloat;
class APInt;
/// This folding set used for two purposes:
/// 1. Given information about a node we want to create, look up the unique
/// instance of the node in the set. If the node already exists, return
/// it, otherwise return the bucket it should be inserted into.
/// 2. Given a node that has already been created, remove it from the set.
///
/// This class is implemented as a single-link chained hash table, where the
/// "buckets" are actually the nodes themselves (the next pointer is in the
/// node). The last node points back to the bucket to simplify node removal.
///
/// Any node that is to be included in the folding set must be a subclass of
/// FoldingSetNode. The node class must also define a Profile method used to
/// establish the unique bits of data for the node. The Profile method is
/// passed a FoldingSetNodeID object which is used to gather the bits. Just
/// call one of the Add* functions defined in the FoldingSetImpl::NodeID class.
/// NOTE: That the folding set does not own the nodes and it is the
/// responsibility of the user to dispose of the nodes.
///
/// Eg.
/// class MyNode : public FoldingSetNode {
/// private:
/// std::string Name;
/// unsigned Value;
/// public:
/// MyNode(const char *N, unsigned V) : Name(N), Value(V) {}
/// ...
/// void Profile(FoldingSetNodeID &ID) const {
/// ID.AddString(Name);
/// ID.AddInteger(Value);
/// }
/// ...
/// };
///
/// To define the folding set itself use the FoldingSet template;
///
/// Eg.
/// FoldingSet<MyNode> MyFoldingSet;
///
/// Four public methods are available to manipulate the folding set;
///
/// 1) If you have an existing node that you want add to the set but unsure
/// that the node might already exist then call;
///
/// MyNode *M = MyFoldingSet.GetOrInsertNode(N);
///
/// If The result is equal to the input then the node has been inserted.
/// Otherwise, the result is the node existing in the folding set, and the
/// input can be discarded (use the result instead.)
///
/// 2) If you are ready to construct a node but want to check if it already
/// exists, then call FindNodeOrInsertPos with a FoldingSetNodeID of the bits to
/// check;
///
/// FoldingSetNodeID ID;
/// ID.AddString(Name);
/// ID.AddInteger(Value);
/// void *InsertPoint;
///
/// MyNode *M = MyFoldingSet.FindNodeOrInsertPos(ID, InsertPoint);
///
/// If found then M with be non-NULL, else InsertPoint will point to where it
/// should be inserted using InsertNode.
///
/// 3) If you get a NULL result from FindNodeOrInsertPos then you can as a new
/// node with FindNodeOrInsertPos;
///
/// InsertNode(N, InsertPoint);
///
/// 4) Finally, if you want to remove a node from the folding set call;
///
/// bool WasRemoved = RemoveNode(N);
///
/// The result indicates whether the node existed in the folding set.
class FoldingSetNodeID;
//===----------------------------------------------------------------------===//
/// FoldingSetImpl - Implements the folding set functionality. The main
/// structure is an array of buckets. Each bucket is indexed by the hash of
/// the nodes it contains. The bucket itself points to the nodes contained
/// in the bucket via a singly linked list. The last node in the list points
/// back to the bucket to facilitate node removal.
///
class FoldingSetImpl {
protected:
/// Buckets - Array of bucket chains.
///
void **Buckets;
/// NumBuckets - Length of the Buckets array. Always a power of 2.
///
unsigned NumBuckets;
/// NumNodes - Number of nodes in the folding set. Growth occurs when NumNodes
/// is greater than twice the number of buckets.
unsigned NumNodes;
public:
explicit FoldingSetImpl(unsigned Log2InitSize = 6);
virtual ~FoldingSetImpl();
//===--------------------------------------------------------------------===//
/// Node - This class is used to maintain the singly linked bucket list in
/// a folding set.
///
class Node {
private:
// NextInFoldingSetBucket - next link in the bucket list.
void *NextInFoldingSetBucket;
public:
Node() : NextInFoldingSetBucket(0) {}
// Accessors
void *getNextInBucket() const { return NextInFoldingSetBucket; }
void SetNextInBucket(void *N) { NextInFoldingSetBucket = N; }
};
/// clear - Remove all nodes from the folding set.
void clear();
/// RemoveNode - Remove a node from the folding set, returning true if one
/// was removed or false if the node was not in the folding set.
bool RemoveNode(Node *N);
/// GetOrInsertNode - If there is an existing simple Node exactly
/// equal to the specified node, return it. Otherwise, insert 'N' and return
/// it instead.
Node *GetOrInsertNode(Node *N);
/// FindNodeOrInsertPos - Look up the node specified by ID. If it exists,
/// return it. If not, return the insertion token that will make insertion
/// faster.
Node *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos);
/// InsertNode - Insert the specified node into the folding set, knowing that
/// it is not already in the folding set. InsertPos must be obtained from
/// FindNodeOrInsertPos.
void InsertNode(Node *N, void *InsertPos);
/// size - Returns the number of nodes in the folding set.
unsigned size() const { return NumNodes; }
/// empty - Returns true if there are no nodes in the folding set.
bool empty() const { return NumNodes == 0; }
private:
/// GrowHashTable - Double the size of the hash table and rehash everything.
///
void GrowHashTable();
protected:
/// GetNodeProfile - Instantiations of the FoldingSet template implement
/// this function to gather data bits for the given node.
virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const = 0;
};
//===----------------------------------------------------------------------===//
/// FoldingSetTrait - This trait class is used to define behavior of how
/// to "profile" (in the FoldingSet parlance) an object of a given type.
/// The default behavior is to invoke a 'Profile' method on an object, but
/// through template specialization the behavior can be tailored for specific
/// types. Combined with the FoldingSetNodeWrapper classs, one can add objects
/// to FoldingSets that were not originally designed to have that behavior.
///
template<typename T> struct FoldingSetTrait {
static inline void Profile(const T& X, FoldingSetNodeID& ID) { X.Profile(ID);}
static inline void Profile(T& X, FoldingSetNodeID& ID) { X.Profile(ID); }
};
//===--------------------------------------------------------------------===//
/// FoldingSetNodeID - This class is used to gather all the unique data bits of
/// a node. When all the bits are gathered this class is used to produce a
/// hash value for the node.
///
class FoldingSetNodeID {
/// Bits - Vector of all the data bits that make the node unique.
/// Use a SmallVector to avoid a heap allocation in the common case.
SmallVector<unsigned, 32> Bits;
public:
FoldingSetNodeID() {}
/// getRawData - Return the ith entry in the Bits data.
///
unsigned getRawData(unsigned i) const {
return Bits[i];
}
/// Add* - Add various data types to Bit data.
///
void AddPointer(const void *Ptr);
void AddInteger(signed I);
void AddInteger(unsigned I);
void AddInteger(long I);
void AddInteger(unsigned long I);
void AddInteger(long long I);
void AddInteger(unsigned long long I);
void AddBoolean(bool B) { AddInteger(B ? 1U : 0U); }
void AddString(const char* String, const char* End);
void AddString(const std::string &String);
void AddString(const char* String);
template <typename T>
inline void Add(const T& x) { FoldingSetTrait<T>::Profile(x, *this); }
/// clear - Clear the accumulated profile, allowing this FoldingSetNodeID
/// object to be used to compute a new profile.
inline void clear() { Bits.clear(); }
/// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used
/// to lookup the node in the FoldingSetImpl.
unsigned ComputeHash() const;
/// operator== - Used to compare two nodes to each other.
///
bool operator==(const FoldingSetNodeID &RHS) const;
};
// Convenience type to hide the implementation of the folding set.
typedef FoldingSetImpl::Node FoldingSetNode;
template<class T> class FoldingSetIterator;
template<class T> class FoldingSetBucketIterator;
//===----------------------------------------------------------------------===//
/// FoldingSet - This template class is used to instantiate a specialized
/// implementation of the folding set to the node class T. T must be a
/// subclass of FoldingSetNode and implement a Profile function.
///
template<class T> class FoldingSet : public FoldingSetImpl {
private:
/// GetNodeProfile - Each instantiatation of the FoldingSet needs to provide a
/// way to convert nodes into a unique specifier.
virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const {
T *TN = static_cast<T *>(N);
FoldingSetTrait<T>::Profile(*TN,ID);
}
public:
explicit FoldingSet(unsigned Log2InitSize = 6)
: FoldingSetImpl(Log2InitSize)
{}
typedef FoldingSetIterator<T> iterator;
iterator begin() { return iterator(Buckets); }
iterator end() { return iterator(Buckets+NumBuckets); }
typedef FoldingSetIterator<const T> const_iterator;
const_iterator begin() const { return const_iterator(Buckets); }
const_iterator end() const { return const_iterator(Buckets+NumBuckets); }
typedef FoldingSetBucketIterator<T> bucket_iterator;
bucket_iterator bucket_begin(unsigned hash) {
return bucket_iterator(Buckets + (hash & (NumBuckets-1)));
}
bucket_iterator bucket_end(unsigned hash) {
return bucket_iterator(Buckets + (hash & (NumBuckets-1)), true);
}
/// GetOrInsertNode - If there is an existing simple Node exactly
/// equal to the specified node, return it. Otherwise, insert 'N' and
/// return it instead.
T *GetOrInsertNode(Node *N) {
return static_cast<T *>(FoldingSetImpl::GetOrInsertNode(N));
}
/// FindNodeOrInsertPos - Look up the node specified by ID. If it exists,
/// return it. If not, return the insertion token that will make insertion
/// faster.
T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) {
return static_cast<T *>(FoldingSetImpl::FindNodeOrInsertPos(ID, InsertPos));
}
};
//===----------------------------------------------------------------------===//
/// FoldingSetIteratorImpl - This is the common iterator support shared by all
/// folding sets, which knows how to walk the folding set hash table.
class FoldingSetIteratorImpl {
protected:
FoldingSetNode *NodePtr;
FoldingSetIteratorImpl(void **Bucket);
void advance();
public:
bool operator==(const FoldingSetIteratorImpl &RHS) const {
return NodePtr == RHS.NodePtr;
}
bool operator!=(const FoldingSetIteratorImpl &RHS) const {
return NodePtr != RHS.NodePtr;
}
};
template<class T>
class FoldingSetIterator : public FoldingSetIteratorImpl {
public:
explicit FoldingSetIterator(void **Bucket) : FoldingSetIteratorImpl(Bucket) {}
T &operator*() const {
return *static_cast<T*>(NodePtr);
}
T *operator->() const {
return static_cast<T*>(NodePtr);
}
inline FoldingSetIterator& operator++() { // Preincrement
advance();
return *this;
}
FoldingSetIterator operator++(int) { // Postincrement
FoldingSetIterator tmp = *this; ++*this; return tmp;
}
};
//===----------------------------------------------------------------------===//
/// FoldingSetBucketIteratorImpl - This is the common bucket iterator support
/// shared by all folding sets, which knows how to walk a particular bucket
/// of a folding set hash table.
class FoldingSetBucketIteratorImpl {
protected:
void *Ptr;
explicit FoldingSetBucketIteratorImpl(void **Bucket);
FoldingSetBucketIteratorImpl(void **Bucket, bool)
: Ptr(Bucket) {}
void advance() {
void *Probe = static_cast<FoldingSetNode*>(Ptr)->getNextInBucket();
uintptr_t x = reinterpret_cast<uintptr_t>(Probe) & ~0x1;
Ptr = reinterpret_cast<void*>(x);
}
public:
bool operator==(const FoldingSetBucketIteratorImpl &RHS) const {
return Ptr == RHS.Ptr;
}
bool operator!=(const FoldingSetBucketIteratorImpl &RHS) const {
return Ptr != RHS.Ptr;
}
};
template<class T>
class FoldingSetBucketIterator : public FoldingSetBucketIteratorImpl {
public:
explicit FoldingSetBucketIterator(void **Bucket) :
FoldingSetBucketIteratorImpl(Bucket) {}
FoldingSetBucketIterator(void **Bucket, bool) :
FoldingSetBucketIteratorImpl(Bucket, true) {}
T& operator*() const { return *static_cast<T*>(Ptr); }
T* operator->() const { return static_cast<T*>(Ptr); }
inline FoldingSetBucketIterator& operator++() { // Preincrement
advance();
return *this;
}
FoldingSetBucketIterator operator++(int) { // Postincrement
FoldingSetBucketIterator tmp = *this; ++*this; return tmp;
}
};
//===----------------------------------------------------------------------===//
/// FoldingSetNodeWrapper - This template class is used to "wrap" arbitrary
/// types in an enclosing object so that they can be inserted into FoldingSets.
template <typename T>
class FoldingSetNodeWrapper : public FoldingSetNode {
T data;
public:
explicit FoldingSetNodeWrapper(const T& x) : data(x) {}
virtual ~FoldingSetNodeWrapper() {}
template<typename A1>
explicit FoldingSetNodeWrapper(const A1& a1)
: data(a1) {}
template <typename A1, typename A2>
explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2)
: data(a1,a2) {}
template <typename A1, typename A2, typename A3>
explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3)
: data(a1,a2,a3) {}
template <typename A1, typename A2, typename A3, typename A4>
explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3,
const A4& a4)
: data(a1,a2,a3,a4) {}
template <typename A1, typename A2, typename A3, typename A4, typename A5>
explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3,
const A4& a4, const A5& a5)
: data(a1,a2,a3,a4,a5) {}
void Profile(FoldingSetNodeID& ID) { FoldingSetTrait<T>::Profile(data, ID); }
T& getValue() { return data; }
const T& getValue() const { return data; }
operator T&() { return data; }
operator const T&() const { return data; }
};
//===----------------------------------------------------------------------===//
/// FastFoldingSetNode - This is a subclass of FoldingSetNode which stores
/// a FoldingSetNodeID value rather than requiring the node to recompute it
/// each time it is needed. This trades space for speed (which can be
/// significant if the ID is long), and it also permits nodes to drop
/// information that would otherwise only be required for recomputing an ID.
class FastFoldingSetNode : public FoldingSetNode {
FoldingSetNodeID FastID;
protected:
explicit FastFoldingSetNode(const FoldingSetNodeID &ID) : FastID(ID) {}
public:
void Profile(FoldingSetNodeID& ID) { ID = FastID; }
};
//===----------------------------------------------------------------------===//
// Partial specializations of FoldingSetTrait.
template<typename T> struct FoldingSetTrait<T*> {
static inline void Profile(const T* X, FoldingSetNodeID& ID) {
ID.AddPointer(X);
}
static inline void Profile(T* X, FoldingSetNodeID& ID) {
ID.AddPointer(X);
}
};
template<typename T> struct FoldingSetTrait<const T*> {
static inline void Profile(const T* X, FoldingSetNodeID& ID) {
ID.AddPointer(X);
}
};
} // End of namespace llvm.
#endif