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Add hooks to FoldingSetTrait to allow specializations to provide 

implementations of equality comparison and hash computation. This
can be used to optimize node lookup by avoiding creating lots of
temporary ID values just for hashing and comparison purposes.

llvm-svn: 111130
This commit is contained in:
Dan Gohman 2010-08-16 15:30:39 +00:00
parent b8640b6d73
commit 9c9ce53b29
2 changed files with 176 additions and 50 deletions
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137
llvm/include/llvm/ADT/FoldingSet.h
View File

@ -191,25 +191,75 @@ protected:
/// GetNodeProfile - Instantiations of the FoldingSet template implement
/// this function to gather data bits for the given node.
virtual void GetNodeProfile(Node *N, FoldingSetNodeID &ID) const = 0;
/// NodeEquals - Instantiations of the FoldingSet template implement
/// this function to compare the given node with the given ID.
virtual bool NodeEquals(Node *N, const FoldingSetNodeID &ID,
FoldingSetNodeID &TempID) const=0;
/// NodeEquals - Instantiations of the FoldingSet template implement
/// this function to compute a hash value for the given node.
virtual unsigned ComputeNodeHash(Node *N,
FoldingSetNodeID &TempID) const = 0;
};
//===----------------------------------------------------------------------===//
template<typename T> struct FoldingSetTrait;
/// DefaultFoldingSetTrait - This class provides default implementations
/// for FoldingSetTrait implementations.
///
template<typename T> struct DefaultFoldingSetTrait {
static void Profile(const T& X, FoldingSetNodeID& ID) {
X.Profile(ID);
}
static void Profile(T& X, FoldingSetNodeID& ID) {
X.Profile(ID);
}
// Equals - Test if the profile for X would match ID, using TempID
// to compute a temporary ID if necessary. The default implementation
// just calls Profile and does a regular comparison. Implementations
// can override this to provide more efficient implementations.
static inline bool Equals(T &X, const FoldingSetNodeID &ID,
FoldingSetNodeID &TempID);
// ComputeHash - Compute a hash value for X, using TempID to
// compute a temporary ID if necessary. The default implementation
// just calls Profile and does a regular hash computation.
// Implementations can override this to provide more efficient
// implementations.
static inline unsigned ComputeHash(T &X, FoldingSetNodeID &TempID);
};
/// FoldingSetTrait - This trait class is used to define behavior of how
/// to "profile" (in the FoldingSet parlance) an object of a given type.
/// The default behavior is to invoke a 'Profile' method on an object, but
/// through template specialization the behavior can be tailored for specific
/// types. Combined with the FoldingSetNodeWrapper class, one can add objects
/// to FoldingSets that were not originally designed to have that behavior.
///
template<typename T> struct FoldingSetTrait {
static inline void Profile(const T& X, FoldingSetNodeID& ID) { X.Profile(ID);}
static inline void Profile(T& X, FoldingSetNodeID& ID) { X.Profile(ID); }
template <typename Ctx>
static inline void Profile(T &X, FoldingSetNodeID &ID, Ctx Context) {
template<typename T> struct FoldingSetTrait
: public DefaultFoldingSetTrait<T> {};
template<typename T, typename Ctx> struct ContextualFoldingSetTrait;
/// DefaultContextualFoldingSetTrait - Like DefaultFoldingSetTrait, but
/// for ContextualFoldingSets.
template<typename T, typename Ctx>
struct DefaultContextualFoldingSetTrait {
static void Profile(T &X, FoldingSetNodeID &ID, Ctx Context) {
X.Profile(ID, Context);
}
static inline bool Equals(T &X, const FoldingSetNodeID &ID,
FoldingSetNodeID &TempID, Ctx Context);
static inline unsigned ComputeHash(T &X, FoldingSetNodeID &TempID,
Ctx Context);
};
/// ContextualFoldingSetTrait - Like FoldingSetTrait, but for
/// ContextualFoldingSets.
template<typename T, typename Ctx> struct ContextualFoldingSetTrait
: public DefaultContextualFoldingSetTrait<T, Ctx> {};
//===--------------------------------------------------------------------===//
/// FoldingSetNodeIDRef - This class describes a reference to an interned
/// FoldingSetNodeID, which can be a useful to store node id data rather
@ -223,6 +273,12 @@ public:
FoldingSetNodeIDRef() : Data(0), Size(0) {}
FoldingSetNodeIDRef(const unsigned *D, size_t S) : Data(D), Size(S) {}
/// ComputeHash - Compute a strong hash value for this FoldingSetNodeIDRef,
/// used to lookup the node in the FoldingSetImpl.
unsigned ComputeHash() const;
bool operator==(FoldingSetNodeIDRef) const;
const unsigned *getData() const { return Data; }
size_t getSize() const { return Size; }
};
@ -269,6 +325,7 @@ public:
/// operator== - Used to compare two nodes to each other.
///
bool operator==(const FoldingSetNodeID &RHS) const;
bool operator==(const FoldingSetNodeIDRef RHS) const;
/// Intern - Copy this node's data to a memory region allocated from the
/// given allocator and return a FoldingSetNodeIDRef describing the
@ -281,6 +338,39 @@ typedef FoldingSetImpl::Node FoldingSetNode;
template<class T> class FoldingSetIterator;
template<class T> class FoldingSetBucketIterator;
// Definitions of FoldingSetTrait and ContextualFoldingSetTrait functions, which
// require the definition of FoldingSetNodeID.
template<typename T>
inline bool
DefaultFoldingSetTrait<T>::Equals(T &X, const FoldingSetNodeID &ID,
FoldingSetNodeID &TempID) {
FoldingSetTrait<T>::Profile(X, TempID);
return TempID == ID;
}
template<typename T>
inline unsigned
DefaultFoldingSetTrait<T>::ComputeHash(T &X, FoldingSetNodeID &TempID) {
FoldingSetTrait<T>::Profile(X, TempID);
return TempID.ComputeHash();
}
template<typename T, typename Ctx>
inline bool
DefaultContextualFoldingSetTrait<T, Ctx>::Equals(T &X,
const FoldingSetNodeID &ID,
FoldingSetNodeID &TempID,
Ctx Context) {
ContextualFoldingSetTrait<T, Ctx>::Profile(X, TempID, Context);
return TempID == ID;
}
template<typename T, typename Ctx>
inline unsigned
DefaultContextualFoldingSetTrait<T, Ctx>::ComputeHash(T &X,
FoldingSetNodeID &TempID,
Ctx Context) {
ContextualFoldingSetTrait<T, Ctx>::Profile(X, TempID, Context);
return TempID.ComputeHash();
}
//===----------------------------------------------------------------------===//
/// FoldingSet - This template class is used to instantiate a specialized
/// implementation of the folding set to the node class T. T must be a
@ -294,6 +384,20 @@ private:
T *TN = static_cast<T *>(N);
FoldingSetTrait<T>::Profile(*TN, ID);
}
/// NodeEquals - Instantiations may optionally provide a way to compare a
/// node with a specified ID.
virtual bool NodeEquals(Node *N, const FoldingSetNodeID &ID,
FoldingSetNodeID &TempID) const {
T *TN = static_cast<T *>(N);
return FoldingSetTrait<T>::Equals(*TN, ID, TempID);
}
/// NodeEquals - Instantiations may optionally provide a way to compute a
/// hash value directly from a node.
virtual unsigned ComputeNodeHash(Node *N,
FoldingSetNodeID &TempID) const {
T *TN = static_cast<T *>(N);
return FoldingSetTrait<T>::ComputeHash(*TN, TempID);
}
public:
explicit FoldingSet(unsigned Log2InitSize = 6)
@ -357,10 +461,18 @@ private:
virtual void GetNodeProfile(FoldingSetImpl::Node *N,
FoldingSetNodeID &ID) const {
T *TN = static_cast<T *>(N);
// We must use explicit template arguments in case Ctx is a
// reference type.
FoldingSetTrait<T>::template Profile<Ctx>(*TN, ID, Context);
ContextualFoldingSetTrait<T, Ctx>::Profile(*TN, ID, Context);
}
virtual bool NodeEquals(FoldingSetImpl::Node *N,
const FoldingSetNodeID &ID,
FoldingSetNodeID &TempID) const {
T *TN = static_cast<T *>(N);
return ContextualFoldingSetTrait<T, Ctx>::Equals(*TN, ID, TempID, Context);
}
virtual unsigned ComputeNodeHash(FoldingSetImpl::Node *N,
FoldingSetNodeID &TempID) const {
T *TN = static_cast<T *>(N);
return ContextualFoldingSetTrait<T, Ctx>::ComputeHash(*TN, TempID, Context);
}
public:
@ -549,7 +661,7 @@ class FastFoldingSetNode : public FoldingSetNode {
protected:
explicit FastFoldingSetNode(const FoldingSetNodeID &ID) : FastID(ID) {}
public:
void Profile(FoldingSetNodeID& ID) { ID = FastID; }
void Profile(FoldingSetNodeID& ID) const { ID = FastID; }
};
//===----------------------------------------------------------------------===//
@ -559,9 +671,6 @@ template<typename T> struct FoldingSetTrait<T*> {
static inline void Profile(const T* X, FoldingSetNodeID& ID) {
ID.AddPointer(X);
}
static inline void Profile(T* X, FoldingSetNodeID& ID) {
ID.AddPointer(X);
}
};
template<typename T> struct FoldingSetTrait<const T*> {

87
llvm/lib/Support/FoldingSet.cpp
View File

@ -22,6 +22,37 @@
#include <cstring>
using namespace llvm;
//===----------------------------------------------------------------------===//
// FoldingSetNodeIDRef Implementation
/// ComputeHash - Compute a strong hash value for this FoldingSetNodeIDRef,
/// used to lookup the node in the FoldingSetImpl.
unsigned FoldingSetNodeIDRef::ComputeHash() const {
// This is adapted from SuperFastHash by Paul Hsieh.
unsigned Hash = static_cast<unsigned>(Size);
for (const unsigned *BP = Data, *E = BP+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;
}
bool FoldingSetNodeIDRef::operator==(FoldingSetNodeIDRef RHS) const {
if (Size != RHS.Size) return false;
return memcmp(Data, RHS.Data, Size*sizeof(*Data)) == 0;
}
//===----------------------------------------------------------------------===//
// FoldingSetNodeID Implementation
@ -104,31 +135,19 @@ void FoldingSetNodeID::AddString(StringRef String) {
/// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used to
/// lookup the node in the FoldingSetImpl.
unsigned FoldingSetNodeID::ComputeHash() const {
// This is adapted from SuperFastHash by Paul Hsieh.
unsigned Hash = static_cast<unsigned>(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;
return FoldingSetNodeIDRef(&Bits[0], Bits.size()).ComputeHash();
}
/// operator== - Used to compare two nodes to each other.
///
bool FoldingSetNodeID::operator==(const FoldingSetNodeID &RHS)const{
if (Bits.size() != RHS.Bits.size()) return false;
return memcmp(&Bits[0], &RHS.Bits[0], Bits.size()*sizeof(Bits[0])) == 0;
return *this == FoldingSetNodeIDRef(&RHS.Bits[0], RHS.Bits.size());
}
/// operator== - Used to compare two nodes to each other.
///
bool FoldingSetNodeID::operator==(FoldingSetNodeIDRef RHS) const {
return FoldingSetNodeIDRef(&Bits[0], Bits.size()) == RHS;
}
/// Intern - Copy this node's data to a memory region allocated from the
@ -168,10 +187,9 @@ static void **GetBucketPtr(void *NextInBucketPtr) {
/// GetBucketFor - Hash the specified node ID and return the hash bucket for
/// the specified ID.
static void **GetBucketFor(const FoldingSetNodeID &ID,
void **Buckets, unsigned NumBuckets) {
static void **GetBucketFor(unsigned Hash, void **Buckets, unsigned NumBuckets) {
// NumBuckets is always a power of 2.
unsigned BucketNum = ID.ComputeHash() & (NumBuckets-1);
unsigned BucketNum = Hash & (NumBuckets-1);
return Buckets + BucketNum;
}
@ -219,7 +237,7 @@ void FoldingSetImpl::GrowHashTable() {
NumNodes = 0;
// Walk the old buckets, rehashing nodes into their new place.
FoldingSetNodeID ID;
FoldingSetNodeID TempID;
for (unsigned i = 0; i != OldNumBuckets; ++i) {
void *Probe = OldBuckets[i];
if (!Probe) continue;
@ -229,9 +247,10 @@ void FoldingSetImpl::GrowHashTable() {
NodeInBucket->SetNextInBucket(0);
// Insert the node into the new bucket, after recomputing the hash.
GetNodeProfile(NodeInBucket, ID);
InsertNode(NodeInBucket, GetBucketFor(ID, Buckets, NumBuckets));
ID.clear();
InsertNode(NodeInBucket,
GetBucketFor(ComputeNodeHash(NodeInBucket, TempID),
Buckets, NumBuckets));
TempID.clear();
}
}
@ -245,19 +264,18 @@ FoldingSetImpl::Node
*FoldingSetImpl::FindNodeOrInsertPos(const FoldingSetNodeID &ID,
void *&InsertPos) {
void **Bucket = GetBucketFor(ID, Buckets, NumBuckets);
void **Bucket = GetBucketFor(ID.ComputeHash(), Buckets, NumBuckets);
void *Probe = *Bucket;
InsertPos = 0;
FoldingSetNodeID OtherID;
FoldingSetNodeID TempID;
while (Node *NodeInBucket = GetNextPtr(Probe)) {
GetNodeProfile(NodeInBucket, OtherID);
if (OtherID == ID)
if (NodeEquals(NodeInBucket, ID, TempID))
return NodeInBucket;
TempID.clear();
Probe = NodeInBucket->getNextInBucket();
OtherID.clear();
}
// Didn't find the node, return null with the bucket as the InsertPos.
@ -273,9 +291,8 @@ void FoldingSetImpl::InsertNode(Node *N, void *InsertPos) {
// Do we need to grow the hashtable?
if (NumNodes+1 > NumBuckets*2) {
GrowHashTable();
FoldingSetNodeID ID;
GetNodeProfile(N, ID);
InsertPos = GetBucketFor(ID, Buckets, NumBuckets);
FoldingSetNodeID TempID;
InsertPos = GetBucketFor(ComputeNodeHash(N, TempID), Buckets, NumBuckets);
}
++NumNodes;