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