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//===-- Support/FoldingSet.cpp - Uniquing Hash Set --------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file 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.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/MathExtras.h"
#include <cassert>
#include <cstring>
using namespace llvm;
//===----------------------------------------------------------------------===//
// FoldingSetNodeIDRef Implementation
/// ComputeHash - Compute a strong hash value for this FoldingSetNodeIDRef,
/// used to lookup the node in the FoldingSetBase.
unsigned FoldingSetNodeIDRef::ComputeHash() const {
return static_cast<unsigned>(hash_combine_range(Data, Data+Size));
}
bool FoldingSetNodeIDRef::operator==(FoldingSetNodeIDRef RHS) const {
if (Size != RHS.Size) return false;
return memcmp(Data, RHS.Data, Size*sizeof(*Data)) == 0;
}
/// Used to compare the "ordering" of two nodes as defined by the
/// profiled bits and their ordering defined by memcmp().
bool FoldingSetNodeIDRef::operator<(FoldingSetNodeIDRef RHS) const {
if (Size != RHS.Size)
return Size < RHS.Size;
return memcmp(Data, RHS.Data, Size*sizeof(*Data)) < 0;
}
//===----------------------------------------------------------------------===//
// FoldingSetNodeID Implementation
/// Add* - Add various data types to Bit data.
///
void FoldingSetNodeID::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 is inherently unstable. Nothing should depend on the
// ordering of nodes in the folding set.
static_assert(sizeof(uintptr_t) <= sizeof(unsigned long long),
"unexpected pointer size");
AddInteger(reinterpret_cast<uintptr_t>(Ptr));
}
void FoldingSetNodeID::AddInteger(signed I) {
Bits.push_back(I);
}
void FoldingSetNodeID::AddInteger(unsigned I) {
Bits.push_back(I);
}
void FoldingSetNodeID::AddInteger(long I) {
AddInteger((unsigned long)I);
}
void FoldingSetNodeID::AddInteger(unsigned long I) {
if (sizeof(long) == sizeof(int))
AddInteger(unsigned(I));
else if (sizeof(long) == sizeof(long long)) {
AddInteger((unsigned long long)I);
} else {
llvm_unreachable("unexpected sizeof(long)");
}
}
void FoldingSetNodeID::AddInteger(long long I) {
AddInteger((unsigned long long)I);
}
void FoldingSetNodeID::AddInteger(unsigned long long I) {
AddInteger(unsigned(I));
AddInteger(unsigned(I >> 32));
}
void FoldingSetNodeID::AddString(StringRef String) {
unsigned Size = String.size();
Bits.push_back(Size);
if (!Size) return;
unsigned Units = Size / 4;
unsigned Pos = 0;
const unsigned *Base = (const unsigned*) String.data();
// If the string is aligned do a bulk transfer.
if (!((intptr_t)Base & 3)) {
Bits.append(Base, Base + Units);
Pos = (Units + 1) * 4;
} else {
// Otherwise do it the hard way.
// To be compatible with above bulk transfer, we need to take endianness
// into account.
static_assert(sys::IsBigEndianHost || sys::IsLittleEndianHost,
"Unexpected host endianness");
if (sys::IsBigEndianHost) {
for (Pos += 4; Pos <= Size; Pos += 4) {
unsigned V = ((unsigned char)String[Pos - 4] << 24) |
((unsigned char)String[Pos - 3] << 16) |
((unsigned char)String[Pos - 2] << 8) |
(unsigned char)String[Pos - 1];
Bits.push_back(V);
}
} else { // Little-endian host
for (Pos += 4; Pos <= Size; Pos += 4) {
unsigned V = ((unsigned char)String[Pos - 1] << 24) |
((unsigned char)String[Pos - 2] << 16) |
((unsigned char)String[Pos - 3] << 8) |
(unsigned char)String[Pos - 4];
Bits.push_back(V);
}
}
}
// With the leftover bits.
unsigned V = 0;
// Pos will have overshot size by 4 - #bytes left over.
// No need to take endianness into account here - this is always executed.
switch (Pos - Size) {
case 1: V = (V << 8) | (unsigned char)String[Size - 3]; LLVM_FALLTHROUGH;
case 2: V = (V << 8) | (unsigned char)String[Size - 2]; LLVM_FALLTHROUGH;
case 3: V = (V << 8) | (unsigned char)String[Size - 1]; break;
default: return; // Nothing left.
}
Bits.push_back(V);
}
// AddNodeID - Adds the Bit data of another ID to *this.
void FoldingSetNodeID::AddNodeID(const FoldingSetNodeID &ID) {
Bits.append(ID.Bits.begin(), ID.Bits.end());
}
/// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used to
/// lookup the node in the FoldingSetBase.
unsigned FoldingSetNodeID::ComputeHash() const {
return FoldingSetNodeIDRef(Bits.data(), Bits.size()).ComputeHash();
}
/// operator== - Used to compare two nodes to each other.
///
bool FoldingSetNodeID::operator==(const FoldingSetNodeID &RHS) const {
return *this == FoldingSetNodeIDRef(RHS.Bits.data(), RHS.Bits.size());
}
/// operator== - Used to compare two nodes to each other.
///
bool FoldingSetNodeID::operator==(FoldingSetNodeIDRef RHS) const {
return FoldingSetNodeIDRef(Bits.data(), Bits.size()) == RHS;
}
/// Used to compare the "ordering" of two nodes as defined by the
/// profiled bits and their ordering defined by memcmp().
bool FoldingSetNodeID::operator<(const FoldingSetNodeID &RHS) const {
return *this < FoldingSetNodeIDRef(RHS.Bits.data(), RHS.Bits.size());
}
bool FoldingSetNodeID::operator<(FoldingSetNodeIDRef RHS) const {
return FoldingSetNodeIDRef(Bits.data(), Bits.size()) < RHS;
}
/// Intern - Copy this node's data to a memory region allocated from the
/// given allocator and return a FoldingSetNodeIDRef describing the
/// interned data.
FoldingSetNodeIDRef
FoldingSetNodeID::Intern(BumpPtrAllocator &Allocator) const {
unsigned *New = Allocator.Allocate<unsigned>(Bits.size());
std::uninitialized_copy(Bits.begin(), Bits.end(), New);
return FoldingSetNodeIDRef(New, Bits.size());
}
//===----------------------------------------------------------------------===//
/// Helper functions for FoldingSetBase.
/// 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.
static FoldingSetBase::Node *GetNextPtr(void *NextInBucketPtr) {
// The low bit is set if this is the pointer back to the bucket.
if (reinterpret_cast<intptr_t>(NextInBucketPtr) & 1)
return nullptr;
return static_cast<FoldingSetBase::Node*>(NextInBucketPtr);
}
/// testing.
static void **GetBucketPtr(void *NextInBucketPtr) {
intptr_t Ptr = reinterpret_cast<intptr_t>(NextInBucketPtr);
assert((Ptr & 1) && "Not a bucket pointer");
return reinterpret_cast<void**>(Ptr & ~intptr_t(1));
}
/// GetBucketFor - Hash the specified node ID and return the hash bucket for
/// the specified ID.
static void **GetBucketFor(unsigned Hash, void **Buckets, unsigned NumBuckets) {
// NumBuckets is always a power of 2.
unsigned BucketNum = Hash & (NumBuckets-1);
return Buckets + BucketNum;
}
/// AllocateBuckets - Allocated initialized bucket memory.
static void **AllocateBuckets(unsigned NumBuckets) {
void **Buckets = static_cast<void**>(safe_calloc(NumBuckets + 1,
sizeof(void*)));
// Set the very last bucket to be a non-null "pointer".
Buckets[NumBuckets] = reinterpret_cast<void*>(-1);
return Buckets;
}
//===----------------------------------------------------------------------===//
// FoldingSetBase Implementation
void FoldingSetBase::anchor() {}
FoldingSetBase::FoldingSetBase(unsigned Log2InitSize) {
assert(5 < Log2InitSize && Log2InitSize < 32 &&
"Initial hash table size out of range");
NumBuckets = 1 << Log2InitSize;
Buckets = AllocateBuckets(NumBuckets);
NumNodes = 0;
}
FoldingSetBase::FoldingSetBase(FoldingSetBase &&Arg)
: Buckets(Arg.Buckets), NumBuckets(Arg.NumBuckets), NumNodes(Arg.NumNodes) {
Arg.Buckets = nullptr;
Arg.NumBuckets = 0;
Arg.NumNodes = 0;
}
FoldingSetBase &FoldingSetBase::operator=(FoldingSetBase &&RHS) {
free(Buckets); // This may be null if the set is in a moved-from state.
Buckets = RHS.Buckets;
NumBuckets = RHS.NumBuckets;
NumNodes = RHS.NumNodes;
RHS.Buckets = nullptr;
RHS.NumBuckets = 0;
RHS.NumNodes = 0;
return *this;
}
FoldingSetBase::~FoldingSetBase() {
free(Buckets);
}
void FoldingSetBase::clear() {
// Set all but the last bucket to null pointers.
memset(Buckets, 0, NumBuckets*sizeof(void*));
// Set the very last bucket to be a non-null "pointer".
Buckets[NumBuckets] = reinterpret_cast<void*>(-1);
// Reset the node count to zero.
NumNodes = 0;
}
void FoldingSetBase::GrowBucketCount(unsigned NewBucketCount) {
assert((NewBucketCount > NumBuckets) && "Can't shrink a folding set with GrowBucketCount");
assert(isPowerOf2_32(NewBucketCount) && "Bad bucket count!");
void **OldBuckets = Buckets;
unsigned OldNumBuckets = NumBuckets;
// Clear out new buckets.
Buckets = AllocateBuckets(NewBucketCount);
// Set NumBuckets only if allocation of new buckets was succesful
NumBuckets = NewBucketCount;
NumNodes = 0;
// Walk the old buckets, rehashing nodes into their new place.
FoldingSetNodeID TempID;
for (unsigned i = 0; i != OldNumBuckets; ++i) {
void *Probe = OldBuckets[i];
if (!Probe) continue;
while (Node *NodeInBucket = GetNextPtr(Probe)) {
// Figure out the next link, remove NodeInBucket from the old link.
Probe = NodeInBucket->getNextInBucket();
NodeInBucket->SetNextInBucket(nullptr);
// Insert the node into the new bucket, after recomputing the hash.
InsertNode(NodeInBucket,
GetBucketFor(ComputeNodeHash(NodeInBucket, TempID),
Buckets, NumBuckets));
TempID.clear();
}
}
free(OldBuckets);
}
/// GrowHashTable - Double the size of the hash table and rehash everything.
///
void FoldingSetBase::GrowHashTable() {
GrowBucketCount(NumBuckets * 2);
}
void FoldingSetBase::reserve(unsigned EltCount) {
// This will give us somewhere between EltCount / 2 and
// EltCount buckets. This puts us in the load factor
// range of 1.0 - 2.0.
if(EltCount < capacity())
return;
GrowBucketCount(PowerOf2Floor(EltCount));
}
/// FindNodeOrInsertPos - Look up the node specified by ID. If it exists,
/// return it. If not, return the insertion token that will make insertion
/// faster.
FoldingSetBase::Node *
FoldingSetBase::FindNodeOrInsertPos(const FoldingSetNodeID &ID,
void *&InsertPos) {
unsigned IDHash = ID.ComputeHash();
void **Bucket = GetBucketFor(IDHash, Buckets, NumBuckets);
void *Probe = *Bucket;
InsertPos = nullptr;
FoldingSetNodeID TempID;
while (Node *NodeInBucket = GetNextPtr(Probe)) {
if (NodeEquals(NodeInBucket, ID, IDHash, TempID))
return NodeInBucket;
TempID.clear();
Probe = NodeInBucket->getNextInBucket();
}
// Didn't find the node, return null with the bucket as the InsertPos.
InsertPos = Bucket;
return nullptr;
}
/// 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 FoldingSetBase::InsertNode(Node *N, void *InsertPos) {
assert(!N->getNextInBucket());
// Do we need to grow the hashtable?
if (NumNodes+1 > capacity()) {
GrowHashTable();
FoldingSetNodeID TempID;
InsertPos = GetBucketFor(ComputeNodeHash(N, TempID), Buckets, NumBuckets);
}
++NumNodes;
/// 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, setting the low bit to indicate
// that it is a pointer to the bucket.
if (!Next)
Next = reinterpret_cast<void*>(reinterpret_cast<intptr_t>(Bucket)|1);
// Set the node's 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 FoldingSetBase::RemoveNode(Node *N) {
// Because each bucket is a circular list, we don't need to compute N's hash
// to remove it.
void *Ptr = N->getNextInBucket();
if (!Ptr) return false; // Not in folding set.
--NumNodes;
N->SetNextInBucket(nullptr);
// Remember what N originally pointed to, either a bucket or another node.
void *NodeNextPtr = Ptr;
// Chase around the list until we find the node (or bucket) which points to N.
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.
FoldingSetBase::Node *FoldingSetBase::GetOrInsertNode(FoldingSetBase::Node *N) {
FoldingSetNodeID ID;
GetNodeProfile(N, ID);
void *IP;
if (Node *E = FindNodeOrInsertPos(ID, IP))
return E;
InsertNode(N, IP);
return N;
}
//===----------------------------------------------------------------------===//
// FoldingSetIteratorImpl Implementation
FoldingSetIteratorImpl::FoldingSetIteratorImpl(void **Bucket) {
// Skip to the first non-null non-self-cycle bucket.
while (*Bucket != reinterpret_cast<void*>(-1) &&
(!*Bucket || !GetNextPtr(*Bucket)))
++Bucket;
NodePtr = static_cast<FoldingSetNode*>(*Bucket);
}
void FoldingSetIteratorImpl::advance() {
// If there is another link within this bucket, go to it.
void *Probe = NodePtr->getNextInBucket();
if (FoldingSetNode *NextNodeInBucket = GetNextPtr(Probe))
NodePtr = NextNodeInBucket;
else {
// Otherwise, this is the last link in this bucket.
void **Bucket = GetBucketPtr(Probe);
// Skip to the next non-null non-self-cycle bucket.
do {
++Bucket;
} while (*Bucket != reinterpret_cast<void*>(-1) &&
(!*Bucket || !GetNextPtr(*Bucket)));
NodePtr = static_cast<FoldingSetNode*>(*Bucket);
}
}
//===----------------------------------------------------------------------===//
// FoldingSetBucketIteratorImpl Implementation
FoldingSetBucketIteratorImpl::FoldingSetBucketIteratorImpl(void **Bucket) {
Ptr = (!*Bucket || !GetNextPtr(*Bucket)) ? (void*) Bucket : *Bucket;
}