1 //===-- Support/FoldingSet.cpp - Uniquing Hash Set --------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements a hash set that can be used to remove duplication of
11 // nodes in a graph. This code was originally created by Chris Lattner for use
12 // with SelectionDAGCSEMap, but was isolated to provide use across the llvm code
15 //===----------------------------------------------------------------------===//
17 #include "llvm/ADT/FoldingSet.h"
18 #include "llvm/ADT/Hashing.h"
19 #include "llvm/Support/Allocator.h"
20 #include "llvm/Support/ErrorHandling.h"
21 #include "llvm/Support/MathExtras.h"
22 #include "llvm/Support/Host.h"
27 //===----------------------------------------------------------------------===//
28 // FoldingSetNodeIDRef Implementation
30 /// ComputeHash - Compute a strong hash value for this FoldingSetNodeIDRef,
31 /// used to lookup the node in the FoldingSetImpl.
32 unsigned FoldingSetNodeIDRef::ComputeHash() const {
33 return static_cast<unsigned>(hash_combine_range(Data, Data+Size));
36 bool FoldingSetNodeIDRef::operator==(FoldingSetNodeIDRef RHS) const {
37 if (Size != RHS.Size) return false;
38 return memcmp(Data, RHS.Data, Size*sizeof(*Data)) == 0;
41 /// Used to compare the "ordering" of two nodes as defined by the
42 /// profiled bits and their ordering defined by memcmp().
43 bool FoldingSetNodeIDRef::operator<(FoldingSetNodeIDRef RHS) const {
45 return Size < RHS.Size;
46 return memcmp(Data, RHS.Data, Size*sizeof(*Data)) < 0;
49 //===----------------------------------------------------------------------===//
50 // FoldingSetNodeID Implementation
52 /// Add* - Add various data types to Bit data.
54 void FoldingSetNodeID::AddPointer(const void *Ptr) {
55 // Note: this adds pointers to the hash using sizes and endianness that
56 // depend on the host. It doesn't matter however, because hashing on
57 // pointer values in inherently unstable. Nothing should depend on the
58 // ordering of nodes in the folding set.
59 Bits.append(reinterpret_cast<unsigned *>(&Ptr),
60 reinterpret_cast<unsigned *>(&Ptr+1));
62 void FoldingSetNodeID::AddInteger(signed I) {
65 void FoldingSetNodeID::AddInteger(unsigned I) {
68 void FoldingSetNodeID::AddInteger(long I) {
69 AddInteger((unsigned long)I);
71 void FoldingSetNodeID::AddInteger(unsigned long I) {
72 if (sizeof(long) == sizeof(int))
73 AddInteger(unsigned(I));
74 else if (sizeof(long) == sizeof(long long)) {
75 AddInteger((unsigned long long)I);
77 llvm_unreachable("unexpected sizeof(long)");
80 void FoldingSetNodeID::AddInteger(long long I) {
81 AddInteger((unsigned long long)I);
83 void FoldingSetNodeID::AddInteger(unsigned long long I) {
84 AddInteger(unsigned(I));
85 if ((uint64_t)(unsigned)I != I)
86 Bits.push_back(unsigned(I >> 32));
89 void FoldingSetNodeID::AddString(StringRef String) {
90 unsigned Size = String.size();
94 unsigned Units = Size / 4;
96 const unsigned *Base = (const unsigned*) String.data();
98 // If the string is aligned do a bulk transfer.
99 if (!((intptr_t)Base & 3)) {
100 Bits.append(Base, Base + Units);
101 Pos = (Units + 1) * 4;
103 // Otherwise do it the hard way.
104 // To be compatible with above bulk transfer, we need to take endianness
106 if (sys::isBigEndianHost()) {
107 for (Pos += 4; Pos <= Size; Pos += 4) {
108 unsigned V = ((unsigned char)String[Pos - 4] << 24) |
109 ((unsigned char)String[Pos - 3] << 16) |
110 ((unsigned char)String[Pos - 2] << 8) |
111 (unsigned char)String[Pos - 1];
115 assert(sys::isLittleEndianHost() && "Unexpected host endianness");
116 for (Pos += 4; Pos <= Size; Pos += 4) {
117 unsigned V = ((unsigned char)String[Pos - 1] << 24) |
118 ((unsigned char)String[Pos - 2] << 16) |
119 ((unsigned char)String[Pos - 3] << 8) |
120 (unsigned char)String[Pos - 4];
126 // With the leftover bits.
128 // Pos will have overshot size by 4 - #bytes left over.
129 // No need to take endianness into account here - this is always executed.
130 switch (Pos - Size) {
131 case 1: V = (V << 8) | (unsigned char)String[Size - 3]; // Fall thru.
132 case 2: V = (V << 8) | (unsigned char)String[Size - 2]; // Fall thru.
133 case 3: V = (V << 8) | (unsigned char)String[Size - 1]; break;
134 default: return; // Nothing left.
140 // AddNodeID - Adds the Bit data of another ID to *this.
141 void FoldingSetNodeID::AddNodeID(const FoldingSetNodeID &ID) {
142 Bits.append(ID.Bits.begin(), ID.Bits.end());
145 /// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used to
146 /// lookup the node in the FoldingSetImpl.
147 unsigned FoldingSetNodeID::ComputeHash() const {
148 return FoldingSetNodeIDRef(Bits.data(), Bits.size()).ComputeHash();
151 /// operator== - Used to compare two nodes to each other.
153 bool FoldingSetNodeID::operator==(const FoldingSetNodeID &RHS)const{
154 return *this == FoldingSetNodeIDRef(RHS.Bits.data(), RHS.Bits.size());
157 /// operator== - Used to compare two nodes to each other.
159 bool FoldingSetNodeID::operator==(FoldingSetNodeIDRef RHS) const {
160 return FoldingSetNodeIDRef(Bits.data(), Bits.size()) == RHS;
163 /// Used to compare the "ordering" of two nodes as defined by the
164 /// profiled bits and their ordering defined by memcmp().
165 bool FoldingSetNodeID::operator<(const FoldingSetNodeID &RHS)const{
166 return *this < FoldingSetNodeIDRef(RHS.Bits.data(), RHS.Bits.size());
169 bool FoldingSetNodeID::operator<(FoldingSetNodeIDRef RHS) const {
170 return FoldingSetNodeIDRef(Bits.data(), Bits.size()) < RHS;
173 /// Intern - Copy this node's data to a memory region allocated from the
174 /// given allocator and return a FoldingSetNodeIDRef describing the
177 FoldingSetNodeID::Intern(BumpPtrAllocator &Allocator) const {
178 unsigned *New = Allocator.Allocate<unsigned>(Bits.size());
179 std::uninitialized_copy(Bits.begin(), Bits.end(), New);
180 return FoldingSetNodeIDRef(New, Bits.size());
183 //===----------------------------------------------------------------------===//
184 /// Helper functions for FoldingSetImpl.
186 /// GetNextPtr - In order to save space, each bucket is a
187 /// singly-linked-list. In order to make deletion more efficient, we make
188 /// the list circular, so we can delete a node without computing its hash.
189 /// The problem with this is that the start of the hash buckets are not
190 /// Nodes. If NextInBucketPtr is a bucket pointer, this method returns null:
191 /// use GetBucketPtr when this happens.
192 static FoldingSetImpl::Node *GetNextPtr(void *NextInBucketPtr) {
193 // The low bit is set if this is the pointer back to the bucket.
194 if (reinterpret_cast<intptr_t>(NextInBucketPtr) & 1)
197 return static_cast<FoldingSetImpl::Node*>(NextInBucketPtr);
202 static void **GetBucketPtr(void *NextInBucketPtr) {
203 intptr_t Ptr = reinterpret_cast<intptr_t>(NextInBucketPtr);
204 assert((Ptr & 1) && "Not a bucket pointer");
205 return reinterpret_cast<void**>(Ptr & ~intptr_t(1));
208 /// GetBucketFor - Hash the specified node ID and return the hash bucket for
209 /// the specified ID.
210 static void **GetBucketFor(unsigned Hash, void **Buckets, unsigned NumBuckets) {
211 // NumBuckets is always a power of 2.
212 unsigned BucketNum = Hash & (NumBuckets-1);
213 return Buckets + BucketNum;
216 /// AllocateBuckets - Allocated initialized bucket memory.
217 static void **AllocateBuckets(unsigned NumBuckets) {
218 void **Buckets = static_cast<void**>(calloc(NumBuckets+1, sizeof(void*)));
219 // Set the very last bucket to be a non-null "pointer".
220 Buckets[NumBuckets] = reinterpret_cast<void*>(-1);
224 //===----------------------------------------------------------------------===//
225 // FoldingSetImpl Implementation
227 FoldingSetImpl::FoldingSetImpl(unsigned Log2InitSize) {
228 assert(5 < Log2InitSize && Log2InitSize < 32 &&
229 "Initial hash table size out of range");
230 NumBuckets = 1 << Log2InitSize;
231 Buckets = AllocateBuckets(NumBuckets);
234 FoldingSetImpl::~FoldingSetImpl() {
237 void FoldingSetImpl::clear() {
238 // Set all but the last bucket to null pointers.
239 memset(Buckets, 0, NumBuckets*sizeof(void*));
241 // Set the very last bucket to be a non-null "pointer".
242 Buckets[NumBuckets] = reinterpret_cast<void*>(-1);
244 // Reset the node count to zero.
248 /// GrowHashTable - Double the size of the hash table and rehash everything.
250 void FoldingSetImpl::GrowHashTable() {
251 void **OldBuckets = Buckets;
252 unsigned OldNumBuckets = NumBuckets;
255 // Clear out new buckets.
256 Buckets = AllocateBuckets(NumBuckets);
259 // Walk the old buckets, rehashing nodes into their new place.
260 FoldingSetNodeID TempID;
261 for (unsigned i = 0; i != OldNumBuckets; ++i) {
262 void *Probe = OldBuckets[i];
263 if (!Probe) continue;
264 while (Node *NodeInBucket = GetNextPtr(Probe)) {
265 // Figure out the next link, remove NodeInBucket from the old link.
266 Probe = NodeInBucket->getNextInBucket();
267 NodeInBucket->SetNextInBucket(0);
269 // Insert the node into the new bucket, after recomputing the hash.
270 InsertNode(NodeInBucket,
271 GetBucketFor(ComputeNodeHash(NodeInBucket, TempID),
272 Buckets, NumBuckets));
280 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists,
281 /// return it. If not, return the insertion token that will make insertion
284 *FoldingSetImpl::FindNodeOrInsertPos(const FoldingSetNodeID &ID,
286 unsigned IDHash = ID.ComputeHash();
287 void **Bucket = GetBucketFor(IDHash, Buckets, NumBuckets);
288 void *Probe = *Bucket;
292 FoldingSetNodeID TempID;
293 while (Node *NodeInBucket = GetNextPtr(Probe)) {
294 if (NodeEquals(NodeInBucket, ID, IDHash, TempID))
298 Probe = NodeInBucket->getNextInBucket();
301 // Didn't find the node, return null with the bucket as the InsertPos.
306 /// InsertNode - Insert the specified node into the folding set, knowing that it
307 /// is not already in the map. InsertPos must be obtained from
308 /// FindNodeOrInsertPos.
309 void FoldingSetImpl::InsertNode(Node *N, void *InsertPos) {
310 assert(N->getNextInBucket() == 0);
311 // Do we need to grow the hashtable?
312 if (NumNodes+1 > NumBuckets*2) {
314 FoldingSetNodeID TempID;
315 InsertPos = GetBucketFor(ComputeNodeHash(N, TempID), Buckets, NumBuckets);
320 /// The insert position is actually a bucket pointer.
321 void **Bucket = static_cast<void**>(InsertPos);
323 void *Next = *Bucket;
325 // If this is the first insertion into this bucket, its next pointer will be
326 // null. Pretend as if it pointed to itself, setting the low bit to indicate
327 // that it is a pointer to the bucket.
329 Next = reinterpret_cast<void*>(reinterpret_cast<intptr_t>(Bucket)|1);
331 // Set the node's next pointer, and make the bucket point to the node.
332 N->SetNextInBucket(Next);
336 /// RemoveNode - Remove a node from the folding set, returning true if one was
337 /// removed or false if the node was not in the folding set.
338 bool FoldingSetImpl::RemoveNode(Node *N) {
339 // Because each bucket is a circular list, we don't need to compute N's hash
341 void *Ptr = N->getNextInBucket();
342 if (Ptr == 0) return false; // Not in folding set.
345 N->SetNextInBucket(0);
347 // Remember what N originally pointed to, either a bucket or another node.
348 void *NodeNextPtr = Ptr;
350 // Chase around the list until we find the node (or bucket) which points to N.
352 if (Node *NodeInBucket = GetNextPtr(Ptr)) {
354 Ptr = NodeInBucket->getNextInBucket();
356 // We found a node that points to N, change it to point to N's next node,
357 // removing N from the list.
359 NodeInBucket->SetNextInBucket(NodeNextPtr);
363 void **Bucket = GetBucketPtr(Ptr);
366 // If we found that the bucket points to N, update the bucket to point to
369 *Bucket = NodeNextPtr;
376 /// GetOrInsertNode - If there is an existing simple Node exactly
377 /// equal to the specified node, return it. Otherwise, insert 'N' and it
379 FoldingSetImpl::Node *FoldingSetImpl::GetOrInsertNode(FoldingSetImpl::Node *N) {
381 GetNodeProfile(N, ID);
383 if (Node *E = FindNodeOrInsertPos(ID, IP))
389 //===----------------------------------------------------------------------===//
390 // FoldingSetIteratorImpl Implementation
392 FoldingSetIteratorImpl::FoldingSetIteratorImpl(void **Bucket) {
393 // Skip to the first non-null non-self-cycle bucket.
394 while (*Bucket != reinterpret_cast<void*>(-1) &&
395 (*Bucket == 0 || GetNextPtr(*Bucket) == 0))
398 NodePtr = static_cast<FoldingSetNode*>(*Bucket);
401 void FoldingSetIteratorImpl::advance() {
402 // If there is another link within this bucket, go to it.
403 void *Probe = NodePtr->getNextInBucket();
405 if (FoldingSetNode *NextNodeInBucket = GetNextPtr(Probe))
406 NodePtr = NextNodeInBucket;
408 // Otherwise, this is the last link in this bucket.
409 void **Bucket = GetBucketPtr(Probe);
411 // Skip to the next non-null non-self-cycle bucket.
414 } while (*Bucket != reinterpret_cast<void*>(-1) &&
415 (*Bucket == 0 || GetNextPtr(*Bucket) == 0));
417 NodePtr = static_cast<FoldingSetNode*>(*Bucket);
421 //===----------------------------------------------------------------------===//
422 // FoldingSetBucketIteratorImpl Implementation
424 FoldingSetBucketIteratorImpl::FoldingSetBucketIteratorImpl(void **Bucket) {
425 Ptr = (*Bucket == 0 || GetNextPtr(*Bucket) == 0) ? (void*) Bucket : *Bucket;