[llvm-commits] CVS: llvm/include/llvm/ADT/FoldingSet.h
Jim Laskey
jlaskey at apple.com
Fri Oct 27 09:16:33 PDT 2006
Changes in directory llvm/include/llvm/ADT:
FoldingSet.h added (r1.1)
---
Log message:
Breakout folding hash set from SelectionDAGCSEMap.
---
Diffs of the changes: (+281 -0)
FoldingSet.h | 281 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 281 insertions(+)
Index: llvm/include/llvm/ADT/FoldingSet.h
diff -c /dev/null llvm/include/llvm/ADT/FoldingSet.h:1.1
*** /dev/null Fri Oct 27 11:16:26 2006
--- llvm/include/llvm/ADT/FoldingSet.h Fri Oct 27 11:16:16 2006
***************
*** 0 ****
--- 1,281 ----
+ //===-- llvm/ADT/FoldingSet.h - Uniquing Hash Set ---------------*- C++ -*-===//
+ //
+ // The LLVM Compiler Infrastructure
+ //
+ // This file was developed by James M. Laskey and 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/ADT/SmallVector.h"
+
+ namespace llvm {
+
+ /// 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 simplified 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.
+ ///
+ /// 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) {
+ /// 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 ass 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 did exist in the folding set.
+
+
+ //===----------------------------------------------------------------------===//
+ /// 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 {
+ private:
+ // 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 teh number of buckets.
+ unsigned NumNodes;
+
+ public:
+ FoldingSetImpl();
+ ~FoldingSetImpl();
+
+ // Forward declaration.
+ class Node;
+
+ //===--------------------------------------------------------------------===//
+ /// NodeID - 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 NodeID {
+ /// 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:
+ NodeID() {}
+
+ /// 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(uint64_t I);
+ void AddFloat(float F);
+ void AddDouble(double D);
+ void AddString(const std::string &String);
+
+ /// ComputeHash - Compute a strong hash value for this NodeID, used to
+ /// lookup the node in the FoldingSetImpl.
+ unsigned ComputeHash() const;
+
+ /// operator== - Used to compare two nodes to each other.
+ ///
+ bool operator==(const NodeID &RHS) const;
+ };
+
+ //===--------------------------------------------------------------------===//
+ /// Node - This class is used to maintain the singly linked bucket list in
+ /// a folding set.
+ ///
+ class Node {
+ private:
+ // nextInBucket - next linek in the bucket list.
+ void *nextInBucket;
+
+ public:
+
+ Node() : nextInBucket(0) {}
+
+ // Accessors
+ void *getNextInBucket() const { return nextInBucket; }
+ void SetNextInBucket(void *N) { nextInBucket = 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 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 NodeID &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);
+
+ private:
+ /// GetNextPtr - In order to save space, each bucket is a
+ /// singly-linked-list. In order to make deletion more efficient, we make
+ /// the list circular, so we can delete a node without computing its hash.
+ /// The problem with this is that the start of the hash buckets are not
+ /// Nodes. If NextInBucketPtr is a bucket pointer, this method returns null
+ /// : use GetBucketPtr when this happens.
+ Node *GetNextPtr(void *NextInBucketPtr);
+
+ /// GetNextPtr - This is just like the previous GetNextPtr implementation,
+ /// but allows a bucket array to be specified.
+ Node *GetNextPtr(void *NextInBucketPtr, void **Buckets, unsigned NumBuck);
+
+ /// GetBucketPtr - Provides a casting of a bucket pointer for isNode
+ /// testing.
+ void **GetBucketPtr(void *NextInBucketPtr);
+
+ /// GetBucketFor - Hash the specified node ID and return the hash bucket for
+ /// the specified ID.
+ void **GetBucketFor(const NodeID &ID) const;
+
+ /// 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 teh given node.
+ virtual void GetNodeProfile(NodeID &ID, Node *N) = 0;
+ };
+
+ // Convenence types to hide the implementation of the folding set.
+ typedef FoldingSetImpl::Node FoldingSetNode;
+ typedef FoldingSetImpl::NodeID FoldingSetNodeID;
+
+ //===--------------------------------------------------------------------===//
+ /// 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
+ virtual void GetNodeProfile(NodeID &ID, Node *N) {
+ T *TN = static_cast<T *>(N);
+ TN->Profile(ID);
+ }
+
+ public:
+ /// 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(T *N) {
+ return FoldingSetImpl::RemoveNode(static_cast<FoldingSetNode *>(N));
+ }
+
+ /// 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(
+ static_cast<FoldingSetNode *>(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));
+ }
+
+ /// 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(T *N, void *InsertPos) {
+ FoldingSetImpl::InsertNode(static_cast<FoldingSetNode *>(N), InsertPos);
+ }
+ };
+
+ }; // End of namespace llvm.
+
+
+ #endif
+
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