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Breakout folding hash set from SelectionDAGCSEMap.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31215 91177308-0d34-0410-b5e6-96231b3b80d8
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include/llvm/ADT/FoldingSet.h
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281
include/llvm/ADT/FoldingSet.h
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//===-- 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/ADT/SmallVector.h"
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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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///
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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 ass 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 did exist 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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void **Buckets;
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// NumBuckets - Length of the Buckets array. Always a power of 2.
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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 teh number of buckets.
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unsigned NumNodes;
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public:
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FoldingSetImpl();
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~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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// nextInBucket - next linek in the bucket list.
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void *nextInBucket;
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public:
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Node() : nextInBucket(0) {}
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// Accessors
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void *getNextInBucket() const { return nextInBucket; }
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void SetNextInBucket(void *N) { nextInBucket = 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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/// GetNextPtr - In order to save space, each bucket is a
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/// singly-linked-list. In order to make deletion more efficient, we make
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/// the list circular, so we can delete a node without computing its hash.
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/// The problem with this is that the start of the hash buckets are not
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/// Nodes. If NextInBucketPtr is a bucket pointer, this method returns null
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/// : use GetBucketPtr when this happens.
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Node *GetNextPtr(void *NextInBucketPtr);
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/// GetNextPtr - This is just like the previous GetNextPtr implementation,
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/// but allows a bucket array to be specified.
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Node *GetNextPtr(void *NextInBucketPtr, void **Buckets, unsigned NumBuck);
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/// GetBucketPtr - Provides a casting of a bucket pointer for isNode
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/// testing.
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void **GetBucketPtr(void *NextInBucketPtr);
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/// GetBucketFor - Hash the specified node ID and return the hash bucket for
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/// the specified ID.
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void **GetBucketFor(const NodeID &ID) const;
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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 teh given node.
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virtual void GetNodeProfile(NodeID &ID, Node *N) = 0;
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};
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// Convenence 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
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virtual void GetNodeProfile(NodeID &ID, Node *N) {
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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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/// 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(T *N) {
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return FoldingSetImpl::RemoveNode(static_cast<FoldingSetNode *>(N));
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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(
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static_cast<FoldingSetNode *>(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,
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InsertPos));
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}
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/// InsertNode - Insert the specified node into the folding set, knowing
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/// that it is not already in the folding set. InsertPos must be obtained
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/// from FindNodeOrInsertPos.
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void InsertNode(T *N, void *InsertPos) {
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FoldingSetImpl::InsertNode(static_cast<FoldingSetNode *>(N), 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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282
lib/Support/FoldingSet.cpp
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282
lib/Support/FoldingSet.cpp
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//===-- Support/FoldingSet.cpp - 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 implements a hash set that can be used to remove duplication of
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// nodes in a graph. This code was originally created by Chris Lattner for use
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// with SelectionDAGCSEMap, but was isolated to provide use across the llvm code
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// set.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/FoldingSet.h"
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#include "llvm/ADT/MathExtras.h"
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using namespace llvm;
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//===----------------------------------------------------------------------===//
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// FoldingSetImpl::NodeID Implementation
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/// Add* - Add various data types to Bit data.
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///
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void FoldingSetImpl::NodeID::AddPointer(const void *Ptr) {
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// Note: this adds pointers to the hash using sizes and endianness that
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// depend on the host. It doesn't matter however, because hashing on
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// pointer values in inherently unstable. Nothing should depend on the
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// ordering of nodes in the folding set.
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intptr_t PtrI = (intptr_t)Ptr;
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Bits.push_back(unsigned(PtrI));
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if (sizeof(intptr_t) > sizeof(unsigned))
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Bits.push_back(unsigned(uint64_t(PtrI) >> 32));
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}
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void FoldingSetImpl::NodeID::AddInteger(signed I) {
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Bits.push_back(I);
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}
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void FoldingSetImpl::NodeID::AddInteger(unsigned I) {
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Bits.push_back(I);
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}
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void FoldingSetImpl::NodeID::AddInteger(uint64_t I) {
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Bits.push_back(unsigned(I));
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Bits.push_back(unsigned(I >> 32));
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}
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void FoldingSetImpl::NodeID::AddFloat(float F) {
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Bits.push_back(FloatToBits(F));
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}
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void FoldingSetImpl::NodeID::AddDouble(double D) {
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Bits.push_back(DoubleToBits(D));
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}
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void FoldingSetImpl::NodeID::AddString(const std::string &String) {
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// Note: An assumption is made here that strings are composed of one byte
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// chars.
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unsigned Size = String.size();
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unsigned Units = Size / sizeof(unsigned);
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const unsigned *Base = (const unsigned *)String.data();
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Bits.insert(Bits.end(), Base, Base + Units);
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if (Size & 3) {
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unsigned V = 0;
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for (unsigned i = Units * sizeof(unsigned); i < Size; ++i)
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V = (V << 8) | String[i];
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Bits.push_back(V);
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}
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}
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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 FoldingSetImpl::NodeID::ComputeHash() const {
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// This is adapted from SuperFastHash by Paul Hsieh.
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unsigned Hash = Bits.size();
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for (const unsigned *BP = &Bits[0], *E = BP+Bits.size(); BP != E; ++BP) {
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unsigned Data = *BP;
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Hash += Data & 0xFFFF;
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unsigned Tmp = ((Data >> 16) << 11) ^ Hash;
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Hash = (Hash << 16) ^ Tmp;
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Hash += Hash >> 11;
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}
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// Force "avalanching" of final 127 bits.
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Hash ^= Hash << 3;
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Hash += Hash >> 5;
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Hash ^= Hash << 4;
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Hash += Hash >> 17;
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Hash ^= Hash << 25;
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Hash += Hash >> 6;
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return Hash;
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}
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/// operator== - Used to compare two nodes to each other.
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///
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bool FoldingSetImpl::NodeID::operator==(const FoldingSetImpl::NodeID &RHS)const{
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if (Bits.size() != RHS.Bits.size()) return false;
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return memcmp(&Bits[0], &RHS.Bits[0], Bits.size()*sizeof(Bits[0])) == 0;
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}
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//===----------------------------------------------------------------------===//
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// FoldingSetImpl Implementation
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FoldingSetImpl::FoldingSetImpl() : NumNodes(0) {
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NumBuckets = 64;
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Buckets = new void*[NumBuckets];
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memset(Buckets, 0, NumBuckets*sizeof(void*));
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}
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FoldingSetImpl::~FoldingSetImpl() {
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delete [] Buckets;
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}
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/// GetNextPtr - In order to save space, each bucket is a
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/// singly-linked-list. In order to make deletion more efficient, we make
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/// the list circular, so we can delete a node without computing its hash.
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/// The problem with this is that the start of the hash buckets are not
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/// Nodes. If NextInBucketPtr is a bucket pointer, this method returns null
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/// : use GetBucketPtr when this happens.
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FoldingSetImpl::Node *FoldingSetImpl::GetNextPtr(void *NextInBucketPtr) {
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if (NextInBucketPtr >= Buckets && NextInBucketPtr < Buckets+NumBuckets)
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return 0;
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return static_cast<Node*>(NextInBucketPtr);
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}
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/// GetNextPtr - This is just like the previous GetNextPtr implementation,
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/// but allows a bucket array to be specified.
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FoldingSetImpl::Node *FoldingSetImpl::GetNextPtr(void *NextInBucketPtr,
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void **Bucks,
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unsigned NumBuck) {
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if (NextInBucketPtr >= Bucks && NextInBucketPtr < Bucks+NumBuck)
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return 0;
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return static_cast<Node*>(NextInBucketPtr);
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}
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/// GetBucketPtr - Provides a casting of a bucket pointer for isNode
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/// testing.
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void **FoldingSetImpl::GetBucketPtr(void *NextInBucketPtr) {
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return static_cast<void**>(NextInBucketPtr);
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}
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/// GetBucketFor - Hash the specified node ID and return the hash bucket for
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/// the specified ID.
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void **FoldingSetImpl::GetBucketFor(const NodeID &ID) const {
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// NumBuckets is always a power of 2.
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unsigned BucketNum = ID.ComputeHash() & (NumBuckets-1);
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return Buckets+BucketNum;
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}
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/// GrowHashTable - Double the size of the hash table and rehash everything.
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///
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void FoldingSetImpl::GrowHashTable() {
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void **OldBuckets = Buckets;
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unsigned OldNumBuckets = NumBuckets;
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NumBuckets <<= 1;
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// Reset the node count to zero: we're going to reinsert everything.
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NumNodes = 0;
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// Clear out new buckets.
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Buckets = new void*[NumBuckets];
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memset(Buckets, 0, NumBuckets*sizeof(void*));
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// Walk the old buckets, rehashing nodes into their new place.
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for (unsigned i = 0; i != OldNumBuckets; ++i) {
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void *Probe = OldBuckets[i];
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if (!Probe) continue;
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while (Node *NodeInBucket = GetNextPtr(Probe, OldBuckets, OldNumBuckets)){
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// Figure out the next link, remove NodeInBucket from the old link.
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Probe = NodeInBucket->getNextInBucket();
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NodeInBucket->SetNextInBucket(0);
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// Insert the node into the new bucket, after recomputing the hash.
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NodeID ID;
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GetNodeProfile(ID, NodeInBucket);
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InsertNode(NodeInBucket, GetBucketFor(ID));
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}
|
||||
}
|
||||
|
||||
delete[] OldBuckets;
|
||||
}
|
||||
|
||||
/// FindNodeOrInsertPos - Look up the node specified by ID. If it exists,
|
||||
/// return it. If not, return the insertion token that will make insertion
|
||||
/// faster.
|
||||
FoldingSetImpl::Node *FoldingSetImpl::FindNodeOrInsertPos(const NodeID &ID,
|
||||
void *&InsertPos) {
|
||||
void **Bucket = GetBucketFor(ID);
|
||||
void *Probe = *Bucket;
|
||||
|
||||
InsertPos = 0;
|
||||
|
||||
while (Node *NodeInBucket = GetNextPtr(Probe)) {
|
||||
NodeID OtherID;
|
||||
GetNodeProfile(OtherID, NodeInBucket);
|
||||
if (OtherID == ID)
|
||||
return NodeInBucket;
|
||||
|
||||
Probe = NodeInBucket->getNextInBucket();
|
||||
}
|
||||
|
||||
// Didn't find the node, return null with the bucket as the InsertPos.
|
||||
InsertPos = Bucket;
|
||||
return 0;
|
||||
}
|
||||
|
||||
/// InsertNode - Insert the specified node into the folding set, knowing that it
|
||||
/// is not already in the map. InsertPos must be obtained from
|
||||
/// FindNodeOrInsertPos.
|
||||
void FoldingSetImpl::InsertNode(Node *N, void *InsertPos) {
|
||||
++NumNodes;
|
||||
// Do we need to grow the hashtable?
|
||||
if (NumNodes > NumBuckets*2) {
|
||||
GrowHashTable();
|
||||
NodeID ID;
|
||||
GetNodeProfile(ID, N);
|
||||
InsertPos = GetBucketFor(ID);
|
||||
}
|
||||
|
||||
/// The insert position is actually a bucket pointer.
|
||||
void **Bucket = static_cast<void**>(InsertPos);
|
||||
|
||||
void *Next = *Bucket;
|
||||
|
||||
// If this is the first insertion into this bucket, its next pointer will be
|
||||
// null. Pretend as if it pointed to itself.
|
||||
if (Next == 0)
|
||||
Next = Bucket;
|
||||
|
||||
// Set the nodes next pointer, and make the bucket point to the node.
|
||||
N->SetNextInBucket(Next);
|
||||
*Bucket = N;
|
||||
}
|
||||
|
||||
/// 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 FoldingSetImpl::RemoveNode(Node *N) {
|
||||
// Because each bucket is a circular list, we don't need to compute N's hash
|
||||
// to remove it. Chase around the list until we find the node (or bucket)
|
||||
// which points to N.
|
||||
void *Ptr = N->getNextInBucket();
|
||||
if (Ptr == 0) return false; // Not in folding set.
|
||||
|
||||
--NumNodes;
|
||||
|
||||
void *NodeNextPtr = Ptr;
|
||||
N->SetNextInBucket(0);
|
||||
while (true) {
|
||||
if (Node *NodeInBucket = GetNextPtr(Ptr)) {
|
||||
// Advance pointer.
|
||||
Ptr = NodeInBucket->getNextInBucket();
|
||||
|
||||
// We found a node that points to N, change it to point to N's next node,
|
||||
// removing N from the list.
|
||||
if (Ptr == N) {
|
||||
NodeInBucket->SetNextInBucket(NodeNextPtr);
|
||||
return true;
|
||||
}
|
||||
} else {
|
||||
void **Bucket = GetBucketPtr(Ptr);
|
||||
Ptr = *Bucket;
|
||||
|
||||
// If we found that the bucket points to N, update the bucket to point to
|
||||
// whatever is next.
|
||||
if (Ptr == N) {
|
||||
*Bucket = NodeNextPtr;
|
||||
return true;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// GetOrInsertNode - If there is an existing simple Node exactly
|
||||
/// equal to the specified node, return it. Otherwise, insert 'N' and it
|
||||
/// instead.
|
||||
FoldingSetImpl::Node *FoldingSetImpl::GetOrInsertNode(FoldingSetImpl::Node *N) {
|
||||
NodeID ID;
|
||||
GetNodeProfile(ID, N);
|
||||
void *IP;
|
||||
if (Node *E = FindNodeOrInsertPos(ID, IP))
|
||||
return E;
|
||||
InsertNode(N, IP);
|
||||
return N;
|
||||
}
|
Loading…
Reference in New Issue
Block a user