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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33566 91177308-0d34-0410-b5e6-96231b3b80d8
259 lines
8.9 KiB
C++
259 lines
8.9 KiB
C++
//===-- llvm/ADT/FoldingSet.h - Uniquing Hash Set ---------------*- 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 James M. Laskey 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 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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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_FOLDINGSET_H
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#define LLVM_ADT_FOLDINGSET_H
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#include "llvm/Support/DataTypes.h"
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#include "llvm/ADT/SmallVector.h"
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#include <string>
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namespace llvm {
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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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///
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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 simplified node removal.
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///
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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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///
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/// Eg.
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/// class MyNode : public FoldingSetNode {
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/// private:
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/// std::string Name;
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/// unsigned Value;
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/// public:
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/// MyNode(const char *N, unsigned V) : Name(N), Value(V) {}
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/// ...
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/// void Profile(FoldingSetNodeID &ID) {
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/// ID.AddString(Name);
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/// ID.AddInteger(Value);
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/// }
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/// ...
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/// };
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///
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/// To define the folding set itself use the FoldingSet template;
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///
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/// Eg.
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/// FoldingSet<MyNode> MyFoldingSet;
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///
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/// Four public methods are available to manipulate the folding set;
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///
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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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///
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/// MyNode *M = MyFoldingSet.GetOrInsertNode(N);
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///
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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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///
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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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/// check;
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///
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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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///
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/// MyNode *M = MyFoldingSet.FindNodeOrInsertPos(ID, InsertPoint);
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///
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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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///
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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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///
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/// InsertNode(N, InsertPoint);
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///
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/// 4) Finally, if you want to remove a node from the folding set call;
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///
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/// bool WasRemoved = RemoveNode(N);
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///
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/// The result indicates whether the node existed in the folding set.
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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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///
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class FoldingSetImpl {
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private:
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/// Buckets - Array of bucket chains.
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///
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void **Buckets;
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/// NumBuckets - Length of the Buckets array. Always a power of 2.
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///
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unsigned NumBuckets;
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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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unsigned NumNodes;
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public:
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FoldingSetImpl(unsigned Log2InitSize = 6);
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virtual ~FoldingSetImpl();
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// Forward declaration.
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class Node;
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//===--------------------------------------------------------------------===//
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/// NodeID - This class is used to gather all the unique data bits of a
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/// 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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///
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class NodeID {
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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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public:
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NodeID() {}
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/// getRawData - Return the ith entry in the Bits data.
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///
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unsigned getRawData(unsigned i) const {
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return Bits[i];
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}
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/// Add* - Add various data types to Bit data.
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///
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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(uint64_t I);
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void AddFloat(float F);
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void AddDouble(double D);
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void AddString(const std::string &String);
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/// ComputeHash - Compute a strong hash value for this NodeID, used to
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/// 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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///
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bool operator==(const NodeID &RHS) const;
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};
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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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/// a folding set.
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///
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class Node {
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private:
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// NextInFoldingSetBucket - next link in the bucket list.
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void *NextInFoldingSetBucket;
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public:
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Node() : NextInFoldingSetBucket(0) {}
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// Accessors
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void *getNextInBucket() const { return NextInFoldingSetBucket; }
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void SetNextInBucket(void *N) { NextInFoldingSetBucket = N; }
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};
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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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/// it instead.
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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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/// faster.
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Node *FindNodeOrInsertPos(const NodeID &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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private:
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/// GrowHashTable - Double the size of the hash table and rehash everything.
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///
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void GrowHashTable();
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protected:
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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(NodeID &ID, Node *N) const = 0;
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};
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// Convenience types to hide the implementation of the folding set.
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typedef FoldingSetImpl::Node FoldingSetNode;
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typedef FoldingSetImpl::NodeID FoldingSetNodeID;
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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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///
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template<class T> class FoldingSet : public FoldingSetImpl {
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private:
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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(NodeID &ID, Node *N) const {
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T *TN = static_cast<T *>(N);
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TN->Profile(ID);
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}
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public:
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FoldingSet(unsigned Log2InitSize = 6)
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: FoldingSetImpl(Log2InitSize)
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{}
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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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}
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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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/// faster.
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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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};
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} // End of namespace llvm.
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#endif
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