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Breakout folding hash set from SelectionDAGCSEMap.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31215 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jim Laskey 2006-10-27 16:16:16 +00:00
parent c50209bf68
commit 0e5af195f6
2 changed files with 563 additions and 0 deletions
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281
include/llvm/ADT/FoldingSet.h Normal file
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//===-- 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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lib/Support/FoldingSet.cpp Normal file
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//===-- Support/FoldingSet.cpp - 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 implements 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.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/MathExtras.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
// FoldingSetImpl::NodeID Implementation
/// Add* - Add various data types to Bit data.
///
void FoldingSetImpl::NodeID::AddPointer(const void *Ptr) {
// Note: this adds pointers to the hash using sizes and endianness that
// depend on the host. It doesn't matter however, because hashing on
// pointer values in inherently unstable. Nothing should depend on the
// ordering of nodes in the folding set.
intptr_t PtrI = (intptr_t)Ptr;
Bits.push_back(unsigned(PtrI));
if (sizeof(intptr_t) > sizeof(unsigned))
Bits.push_back(unsigned(uint64_t(PtrI) >> 32));
}
void FoldingSetImpl::NodeID::AddInteger(signed I) {
Bits.push_back(I);
}
void FoldingSetImpl::NodeID::AddInteger(unsigned I) {
Bits.push_back(I);
}
void FoldingSetImpl::NodeID::AddInteger(uint64_t I) {
Bits.push_back(unsigned(I));
Bits.push_back(unsigned(I >> 32));
}
void FoldingSetImpl::NodeID::AddFloat(float F) {
Bits.push_back(FloatToBits(F));
}
void FoldingSetImpl::NodeID::AddDouble(double D) {
Bits.push_back(DoubleToBits(D));
}
void FoldingSetImpl::NodeID::AddString(const std::string &String) {
// Note: An assumption is made here that strings are composed of one byte
// chars.
unsigned Size = String.size();
unsigned Units = Size / sizeof(unsigned);
const unsigned *Base = (const unsigned *)String.data();
Bits.insert(Bits.end(), Base, Base + Units);
if (Size & 3) {
unsigned V = 0;
for (unsigned i = Units * sizeof(unsigned); i < Size; ++i)
V = (V << 8) | String[i];
Bits.push_back(V);
}
}
/// ComputeHash - Compute a strong hash value for this NodeID, used to
/// lookup the node in the FoldingSetImpl.
unsigned FoldingSetImpl::NodeID::ComputeHash() const {
// This is adapted from SuperFastHash by Paul Hsieh.
unsigned Hash = Bits.size();
for (const unsigned *BP = &Bits[0], *E = BP+Bits.size(); BP != E; ++BP) {
unsigned Data = *BP;
Hash += Data & 0xFFFF;
unsigned Tmp = ((Data >> 16) << 11) ^ Hash;
Hash = (Hash << 16) ^ Tmp;
Hash += Hash >> 11;
}
// Force "avalanching" of final 127 bits.
Hash ^= Hash << 3;
Hash += Hash >> 5;
Hash ^= Hash << 4;
Hash += Hash >> 17;
Hash ^= Hash << 25;
Hash += Hash >> 6;
return Hash;
}
/// operator== - Used to compare two nodes to each other.
///
bool FoldingSetImpl::NodeID::operator==(const FoldingSetImpl::NodeID &RHS)const{
if (Bits.size() != RHS.Bits.size()) return false;
return memcmp(&Bits[0], &RHS.Bits[0], Bits.size()*sizeof(Bits[0])) == 0;
}
//===----------------------------------------------------------------------===//
// FoldingSetImpl Implementation
FoldingSetImpl::FoldingSetImpl() : NumNodes(0) {
NumBuckets = 64;
Buckets = new void*[NumBuckets];
memset(Buckets, 0, NumBuckets*sizeof(void*));
}
FoldingSetImpl::~FoldingSetImpl() {
delete [] Buckets;
}
/// 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.
FoldingSetImpl::Node *FoldingSetImpl::GetNextPtr(void *NextInBucketPtr) {
if (NextInBucketPtr >= Buckets && NextInBucketPtr < Buckets+NumBuckets)
return 0;
return static_cast<Node*>(NextInBucketPtr);
}
/// GetNextPtr - This is just like the previous GetNextPtr implementation,
/// but allows a bucket array to be specified.
FoldingSetImpl::Node *FoldingSetImpl::GetNextPtr(void *NextInBucketPtr,
void **Bucks,
unsigned NumBuck) {
if (NextInBucketPtr >= Bucks && NextInBucketPtr < Bucks+NumBuck)
return 0;
return static_cast<Node*>(NextInBucketPtr);
}
/// GetBucketPtr - Provides a casting of a bucket pointer for isNode
/// testing.
void **FoldingSetImpl::GetBucketPtr(void *NextInBucketPtr) {
return static_cast<void**>(NextInBucketPtr);
}
/// GetBucketFor - Hash the specified node ID and return the hash bucket for
/// the specified ID.
void **FoldingSetImpl::GetBucketFor(const NodeID &ID) const {
// NumBuckets is always a power of 2.
unsigned BucketNum = ID.ComputeHash() & (NumBuckets-1);
return Buckets+BucketNum;
}
/// GrowHashTable - Double the size of the hash table and rehash everything.
///
void FoldingSetImpl::GrowHashTable() {
void **OldBuckets = Buckets;
unsigned OldNumBuckets = NumBuckets;
NumBuckets <<= 1;
// Reset the node count to zero: we're going to reinsert everything.
NumNodes = 0;
// Clear out new buckets.
Buckets = new void*[NumBuckets];
memset(Buckets, 0, NumBuckets*sizeof(void*));
// Walk the old buckets, rehashing nodes into their new place.
for (unsigned i = 0; i != OldNumBuckets; ++i) {
void *Probe = OldBuckets[i];
if (!Probe) continue;
while (Node *NodeInBucket = GetNextPtr(Probe, OldBuckets, OldNumBuckets)){
// Figure out the next link, remove NodeInBucket from the old link.
Probe = NodeInBucket->getNextInBucket();
NodeInBucket->SetNextInBucket(0);
// Insert the node into the new bucket, after recomputing the hash.
NodeID ID;
GetNodeProfile(ID, NodeInBucket);
InsertNode(NodeInBucket, GetBucketFor(ID));
}
}
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;
}