LLVM  3.7.0
FoldingSet.cpp
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1 //===-- Support/FoldingSet.cpp - Uniquing Hash Set --------------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements a hash set that can be used to remove duplication of
11 // nodes in a graph.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/ADT/FoldingSet.h"
16 #include "llvm/ADT/Hashing.h"
17 #include "llvm/Support/Allocator.h"
19 #include "llvm/Support/Host.h"
21 #include <cassert>
22 #include <cstring>
23 using namespace llvm;
24 
25 //===----------------------------------------------------------------------===//
26 // FoldingSetNodeIDRef Implementation
27 
28 /// ComputeHash - Compute a strong hash value for this FoldingSetNodeIDRef,
29 /// used to lookup the node in the FoldingSetImpl.
31  return static_cast<unsigned>(hash_combine_range(Data, Data+Size));
32 }
33 
35  if (Size != RHS.Size) return false;
36  return memcmp(Data, RHS.Data, Size*sizeof(*Data)) == 0;
37 }
38 
39 /// Used to compare the "ordering" of two nodes as defined by the
40 /// profiled bits and their ordering defined by memcmp().
42  if (Size != RHS.Size)
43  return Size < RHS.Size;
44  return memcmp(Data, RHS.Data, Size*sizeof(*Data)) < 0;
45 }
46 
47 //===----------------------------------------------------------------------===//
48 // FoldingSetNodeID Implementation
49 
50 /// Add* - Add various data types to Bit data.
51 ///
52 void FoldingSetNodeID::AddPointer(const void *Ptr) {
53  // Note: this adds pointers to the hash using sizes and endianness that
54  // depend on the host. It doesn't matter, however, because hashing on
55  // pointer values is inherently unstable. Nothing should depend on the
56  // ordering of nodes in the folding set.
57  Bits.append(reinterpret_cast<unsigned *>(&Ptr),
58  reinterpret_cast<unsigned *>(&Ptr+1));
59 }
61  Bits.push_back(I);
62 }
64  Bits.push_back(I);
65 }
67  AddInteger((unsigned long)I);
68 }
69 void FoldingSetNodeID::AddInteger(unsigned long I) {
70  if (sizeof(long) == sizeof(int))
71  AddInteger(unsigned(I));
72  else if (sizeof(long) == sizeof(long long)) {
73  AddInteger((unsigned long long)I);
74  } else {
75  llvm_unreachable("unexpected sizeof(long)");
76  }
77 }
79  AddInteger((unsigned long long)I);
80 }
81 void FoldingSetNodeID::AddInteger(unsigned long long I) {
82  AddInteger(unsigned(I));
83  if ((uint64_t)(unsigned)I != I)
84  Bits.push_back(unsigned(I >> 32));
85 }
86 
88  unsigned Size = String.size();
89  Bits.push_back(Size);
90  if (!Size) return;
91 
92  unsigned Units = Size / 4;
93  unsigned Pos = 0;
94  const unsigned *Base = (const unsigned*) String.data();
95 
96  // If the string is aligned do a bulk transfer.
97  if (!((intptr_t)Base & 3)) {
98  Bits.append(Base, Base + Units);
99  Pos = (Units + 1) * 4;
100  } else {
101  // Otherwise do it the hard way.
102  // To be compatible with above bulk transfer, we need to take endianness
103  // into account.
105  "Unexpected host 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];
112  Bits.push_back(V);
113  }
114  } else { // Little-endian host
115  for (Pos += 4; Pos <= Size; Pos += 4) {
116  unsigned V = ((unsigned char)String[Pos - 1] << 24) |
117  ((unsigned char)String[Pos - 2] << 16) |
118  ((unsigned char)String[Pos - 3] << 8) |
119  (unsigned char)String[Pos - 4];
120  Bits.push_back(V);
121  }
122  }
123  }
124 
125  // With the leftover bits.
126  unsigned V = 0;
127  // Pos will have overshot size by 4 - #bytes left over.
128  // No need to take endianness into account here - this is always executed.
129  switch (Pos - Size) {
130  case 1: V = (V << 8) | (unsigned char)String[Size - 3]; // Fall thru.
131  case 2: V = (V << 8) | (unsigned char)String[Size - 2]; // Fall thru.
132  case 3: V = (V << 8) | (unsigned char)String[Size - 1]; break;
133  default: return; // Nothing left.
134  }
135 
136  Bits.push_back(V);
137 }
138 
139 // AddNodeID - Adds the Bit data of another ID to *this.
141  Bits.append(ID.Bits.begin(), ID.Bits.end());
142 }
143 
144 /// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used to
145 /// lookup the node in the FoldingSetImpl.
147  return FoldingSetNodeIDRef(Bits.data(), Bits.size()).ComputeHash();
148 }
149 
150 /// operator== - Used to compare two nodes to each other.
151 ///
153  return *this == FoldingSetNodeIDRef(RHS.Bits.data(), RHS.Bits.size());
154 }
155 
156 /// operator== - Used to compare two nodes to each other.
157 ///
159  return FoldingSetNodeIDRef(Bits.data(), Bits.size()) == RHS;
160 }
161 
162 /// Used to compare the "ordering" of two nodes as defined by the
163 /// profiled bits and their ordering defined by memcmp().
165  return *this < FoldingSetNodeIDRef(RHS.Bits.data(), RHS.Bits.size());
166 }
167 
169  return FoldingSetNodeIDRef(Bits.data(), Bits.size()) < RHS;
170 }
171 
172 /// Intern - Copy this node's data to a memory region allocated from the
173 /// given allocator and return a FoldingSetNodeIDRef describing the
174 /// interned data.
177  unsigned *New = Allocator.Allocate<unsigned>(Bits.size());
178  std::uninitialized_copy(Bits.begin(), Bits.end(), New);
179  return FoldingSetNodeIDRef(New, Bits.size());
180 }
181 
182 //===----------------------------------------------------------------------===//
183 /// Helper functions for FoldingSetImpl.
184 
185 /// GetNextPtr - In order to save space, each bucket is a
186 /// singly-linked-list. In order to make deletion more efficient, we make
187 /// the list circular, so we can delete a node without computing its hash.
188 /// The problem with this is that the start of the hash buckets are not
189 /// Nodes. If NextInBucketPtr is a bucket pointer, this method returns null:
190 /// use GetBucketPtr when this happens.
191 static FoldingSetImpl::Node *GetNextPtr(void *NextInBucketPtr) {
192  // The low bit is set if this is the pointer back to the bucket.
193  if (reinterpret_cast<intptr_t>(NextInBucketPtr) & 1)
194  return nullptr;
195 
196  return static_cast<FoldingSetImpl::Node*>(NextInBucketPtr);
197 }
198 
199 
200 /// testing.
201 static void **GetBucketPtr(void *NextInBucketPtr) {
202  intptr_t Ptr = reinterpret_cast<intptr_t>(NextInBucketPtr);
203  assert((Ptr & 1) && "Not a bucket pointer");
204  return reinterpret_cast<void**>(Ptr & ~intptr_t(1));
205 }
206 
207 /// GetBucketFor - Hash the specified node ID and return the hash bucket for
208 /// the specified ID.
209 static void **GetBucketFor(unsigned Hash, void **Buckets, unsigned NumBuckets) {
210  // NumBuckets is always a power of 2.
211  unsigned BucketNum = Hash & (NumBuckets-1);
212  return Buckets + BucketNum;
213 }
214 
215 /// AllocateBuckets - Allocated initialized bucket memory.
216 static void **AllocateBuckets(unsigned NumBuckets) {
217  void **Buckets = static_cast<void**>(calloc(NumBuckets+1, sizeof(void*)));
218  // Set the very last bucket to be a non-null "pointer".
219  Buckets[NumBuckets] = reinterpret_cast<void*>(-1);
220  return Buckets;
221 }
222 
223 //===----------------------------------------------------------------------===//
224 // FoldingSetImpl Implementation
225 
226 void FoldingSetImpl::anchor() {}
227 
228 FoldingSetImpl::FoldingSetImpl(unsigned Log2InitSize) {
229  assert(5 < Log2InitSize && Log2InitSize < 32 &&
230  "Initial hash table size out of range");
231  NumBuckets = 1 << Log2InitSize;
233  NumNodes = 0;
234 }
236  free(Buckets);
237 }
239  // Set all but the last bucket to null pointers.
240  memset(Buckets, 0, NumBuckets*sizeof(void*));
241 
242  // Set the very last bucket to be a non-null "pointer".
243  Buckets[NumBuckets] = reinterpret_cast<void*>(-1);
244 
245  // Reset the node count to zero.
246  NumNodes = 0;
247 }
248 
249 /// GrowHashTable - Double the size of the hash table and rehash everything.
250 ///
251 void FoldingSetImpl::GrowHashTable() {
252  void **OldBuckets = Buckets;
253  unsigned OldNumBuckets = NumBuckets;
254  NumBuckets <<= 1;
255 
256  // Clear out new buckets.
258  NumNodes = 0;
259 
260  // Walk the old buckets, rehashing nodes into their new place.
261  FoldingSetNodeID TempID;
262  for (unsigned i = 0; i != OldNumBuckets; ++i) {
263  void *Probe = OldBuckets[i];
264  if (!Probe) continue;
265  while (Node *NodeInBucket = GetNextPtr(Probe)) {
266  // Figure out the next link, remove NodeInBucket from the old link.
267  Probe = NodeInBucket->getNextInBucket();
268  NodeInBucket->SetNextInBucket(nullptr);
269 
270  // Insert the node into the new bucket, after recomputing the hash.
271  InsertNode(NodeInBucket,
272  GetBucketFor(ComputeNodeHash(NodeInBucket, TempID),
273  Buckets, NumBuckets));
274  TempID.clear();
275  }
276  }
277 
278  free(OldBuckets);
279 }
280 
281 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists,
282 /// return it. If not, return the insertion token that will make insertion
283 /// faster.
286  void *&InsertPos) {
287  unsigned IDHash = ID.ComputeHash();
288  void **Bucket = GetBucketFor(IDHash, Buckets, NumBuckets);
289  void *Probe = *Bucket;
290 
291  InsertPos = nullptr;
292 
293  FoldingSetNodeID TempID;
294  while (Node *NodeInBucket = GetNextPtr(Probe)) {
295  if (NodeEquals(NodeInBucket, ID, IDHash, TempID))
296  return NodeInBucket;
297  TempID.clear();
298 
299  Probe = NodeInBucket->getNextInBucket();
300  }
301 
302  // Didn't find the node, return null with the bucket as the InsertPos.
303  InsertPos = Bucket;
304  return nullptr;
305 }
306 
307 /// InsertNode - Insert the specified node into the folding set, knowing that it
308 /// is not already in the map. InsertPos must be obtained from
309 /// FindNodeOrInsertPos.
310 void FoldingSetImpl::InsertNode(Node *N, void *InsertPos) {
311  assert(!N->getNextInBucket());
312  // Do we need to grow the hashtable?
313  if (NumNodes+1 > NumBuckets*2) {
314  GrowHashTable();
315  FoldingSetNodeID TempID;
316  InsertPos = GetBucketFor(ComputeNodeHash(N, TempID), Buckets, NumBuckets);
317  }
318 
319  ++NumNodes;
320 
321  /// The insert position is actually a bucket pointer.
322  void **Bucket = static_cast<void**>(InsertPos);
323 
324  void *Next = *Bucket;
325 
326  // If this is the first insertion into this bucket, its next pointer will be
327  // null. Pretend as if it pointed to itself, setting the low bit to indicate
328  // that it is a pointer to the bucket.
329  if (!Next)
330  Next = reinterpret_cast<void*>(reinterpret_cast<intptr_t>(Bucket)|1);
331 
332  // Set the node's next pointer, and make the bucket point to the node.
333  N->SetNextInBucket(Next);
334  *Bucket = N;
335 }
336 
337 /// RemoveNode - Remove a node from the folding set, returning true if one was
338 /// removed or false if the node was not in the folding set.
340  // Because each bucket is a circular list, we don't need to compute N's hash
341  // to remove it.
342  void *Ptr = N->getNextInBucket();
343  if (!Ptr) return false; // Not in folding set.
344 
345  --NumNodes;
346  N->SetNextInBucket(nullptr);
347 
348  // Remember what N originally pointed to, either a bucket or another node.
349  void *NodeNextPtr = Ptr;
350 
351  // Chase around the list until we find the node (or bucket) which points to N.
352  while (true) {
353  if (Node *NodeInBucket = GetNextPtr(Ptr)) {
354  // Advance pointer.
355  Ptr = NodeInBucket->getNextInBucket();
356 
357  // We found a node that points to N, change it to point to N's next node,
358  // removing N from the list.
359  if (Ptr == N) {
360  NodeInBucket->SetNextInBucket(NodeNextPtr);
361  return true;
362  }
363  } else {
364  void **Bucket = GetBucketPtr(Ptr);
365  Ptr = *Bucket;
366 
367  // If we found that the bucket points to N, update the bucket to point to
368  // whatever is next.
369  if (Ptr == N) {
370  *Bucket = NodeNextPtr;
371  return true;
372  }
373  }
374  }
375 }
376 
377 /// GetOrInsertNode - If there is an existing simple Node exactly
378 /// equal to the specified node, return it. Otherwise, insert 'N' and it
379 /// instead.
382  GetNodeProfile(N, ID);
383  void *IP;
384  if (Node *E = FindNodeOrInsertPos(ID, IP))
385  return E;
386  InsertNode(N, IP);
387  return N;
388 }
389 
390 //===----------------------------------------------------------------------===//
391 // FoldingSetIteratorImpl Implementation
392 
394  // Skip to the first non-null non-self-cycle bucket.
395  while (*Bucket != reinterpret_cast<void*>(-1) &&
396  (!*Bucket || !GetNextPtr(*Bucket)))
397  ++Bucket;
398 
399  NodePtr = static_cast<FoldingSetNode*>(*Bucket);
400 }
401 
403  // If there is another link within this bucket, go to it.
404  void *Probe = NodePtr->getNextInBucket();
405 
406  if (FoldingSetNode *NextNodeInBucket = GetNextPtr(Probe))
407  NodePtr = NextNodeInBucket;
408  else {
409  // Otherwise, this is the last link in this bucket.
410  void **Bucket = GetBucketPtr(Probe);
411 
412  // Skip to the next non-null non-self-cycle bucket.
413  do {
414  ++Bucket;
415  } while (*Bucket != reinterpret_cast<void*>(-1) &&
416  (!*Bucket || !GetNextPtr(*Bucket)));
417 
418  NodePtr = static_cast<FoldingSetNode*>(*Bucket);
419  }
420 }
421 
422 //===----------------------------------------------------------------------===//
423 // FoldingSetBucketIteratorImpl Implementation
424 
426  Ptr = (!*Bucket || !GetNextPtr(*Bucket)) ? (void*) Bucket : *Bucket;
427 }
Node * GetOrInsertNode(Node *N)
GetOrInsertNode - If there is an existing simple Node exactly equal to the specified node...
Definition: FoldingSet.cpp:380
void AddPointer(const void *Ptr)
Add* - Add various data types to Bit data.
Definition: FoldingSet.cpp:52
void push_back(const T &Elt)
Definition: SmallVector.h:222
static void ** AllocateBuckets(unsigned NumBuckets)
AllocateBuckets - Allocated initialized bucket memory.
Definition: FoldingSet.cpp:216
size_t size() const
size - Get the string size.
Definition: StringRef.h:113
void ** Buckets
Buckets - Array of bucket chains.
Definition: FoldingSet.h:115
void InsertNode(Node *N, void *InsertPos)
InsertNode - Insert the specified node into the folding set, knowing that it is not already in the fo...
Definition: FoldingSet.cpp:310
This file defines the MallocAllocator and BumpPtrAllocator interfaces.
static void ** GetBucketPtr(void *NextInBucketPtr)
testing.
Definition: FoldingSet.cpp:201
unsigned ComputeHash() const
ComputeHash - Compute a strong hash value for this FoldingSetNodeIDRef, used to lookup the node in th...
Definition: FoldingSet.cpp:30
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition: ErrorHandling.h:98
virtual void GetNodeProfile(Node *N, FoldingSetNodeID &ID) const =0
GetNodeProfile - Instantiations of the FoldingSet template implement this function to gather data bit...
void AddInteger(signed I)
Definition: FoldingSet.cpp:60
static const bool IsLittleEndianHost
Definition: Host.h:38
const char * data() const
data - Get a pointer to the start of the string (which may not be null terminated).
Definition: StringRef.h:107
bool operator==(const FoldingSetNodeID &RHS) const
operator== - Used to compare two nodes to each other.
Definition: FoldingSet.cpp:152
FoldingSetNodeID - This class is used to gather all the unique data bits of a node.
Definition: FoldingSet.h:297
virtual unsigned ComputeNodeHash(Node *N, FoldingSetNodeID &TempID) const =0
ComputeNodeHash - Instantiations of the FoldingSet template implement this function to compute a hash...
void AddNodeID(const FoldingSetNodeID &ID)
Definition: FoldingSet.cpp:140
Allocate memory in an ever growing pool, as if by bump-pointer.
Definition: Allocator.h:135
void * getNextInBucket() const
Definition: FoldingSet.h:144
FoldingSetNode * NodePtr
Definition: FoldingSet.h:604
bool operator<(FoldingSetNodeIDRef) const
Used to compare the "ordering" of two nodes as defined by the profiled bits and their ordering define...
Definition: FoldingSet.cpp:41
LLVM_ATTRIBUTE_RETURNS_NONNULL LLVM_ATTRIBUTE_RETURNS_NOALIAS void * Allocate(size_t Size, size_t Alignment)
Allocate space at the specified alignment.
Definition: Allocator.h:208
static FoldingSetImpl::Node * GetNextPtr(void *NextInBucketPtr)
Helper functions for FoldingSetImpl.
Definition: FoldingSet.cpp:191
Node * FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos)
FindNodeOrInsertPos - Look up the node specified by ID.
Definition: FoldingSet.cpp:285
static void ** GetBucketFor(unsigned Hash, void **Buckets, unsigned NumBuckets)
GetBucketFor - Hash the specified node ID and return the hash bucket for the specified ID...
Definition: FoldingSet.cpp:209
unsigned NumNodes
NumNodes - Number of nodes in the folding set.
Definition: FoldingSet.h:123
FoldingSetImpl(unsigned Log2InitSize=6)
Definition: FoldingSet.cpp:228
void append(in_iter in_start, in_iter in_end)
Add the specified range to the end of the SmallVector.
Definition: SmallVector.h:416
bool RemoveNode(Node *N)
RemoveNode - Remove a node from the folding set, returning true if one was removed or false if the no...
Definition: FoldingSet.cpp:339
bool operator<(const FoldingSetNodeID &RHS) const
Used to compare the "ordering" of two nodes as defined by the profiled bits and their ordering define...
Definition: FoldingSet.cpp:164
void SetNextInBucket(void *N)
Definition: FoldingSet.h:145
void clear()
clear - Clear the accumulated profile, allowing this FoldingSetNodeID object to be used to compute a ...
Definition: FoldingSet.h:326
Node - This class is used to maintain the singly linked bucket list in a folding set.
Definition: FoldingSet.h:134
unsigned NumBuckets
NumBuckets - Length of the Buckets array.
Definition: FoldingSet.h:119
hash_code hash_combine_range(InputIteratorT first, InputIteratorT last)
Compute a hash_code for a sequence of values.
Definition: Hashing.h:481
FoldingSetNodeIDRef - This class describes a reference to an interned FoldingSetNodeID, which can be a useful to store node id data rather than using plain FoldingSetNodeIDs, since the 32-element SmallVector is often much larger than necessary, and the possibility of heap allocation means it requires a non-trivial destructor call.
Definition: FoldingSet.h:269
pointer data()
Return a pointer to the vector's buffer, even if empty().
Definition: SmallVector.h:134
FoldingSetIteratorImpl(void **Bucket)
Definition: FoldingSet.cpp:393
unsigned ComputeHash() const
ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used to lookup the node in the F...
Definition: FoldingSet.cpp:146
static const bool IsBigEndianHost
Definition: Host.h:35
#define I(x, y, z)
Definition: MD5.cpp:54
#define N
void AddString(StringRef String)
Definition: FoldingSet.cpp:87
FoldingSetBucketIteratorImpl(void **Bucket)
Definition: FoldingSet.cpp:425
FoldingSetNodeIDRef Intern(BumpPtrAllocator &Allocator) const
Intern - Copy this node's data to a memory region allocated from the given allocator and return a Fol...
Definition: FoldingSet.cpp:176
std::string Hash(const Unit &U)
Definition: FuzzerUtil.cpp:39
virtual bool NodeEquals(Node *N, const FoldingSetNodeID &ID, unsigned IDHash, FoldingSetNodeID &TempID) const =0
NodeEquals - Instantiations of the FoldingSet template implement this function to compare the given n...
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:40
void clear()
clear - Remove all nodes from the folding set.
Definition: FoldingSet.cpp:238
bool operator==(FoldingSetNodeIDRef) const
Definition: FoldingSet.cpp:34