FoldingSet.cpp revision 226633
166458Sdfr//===-- Support/FoldingSet.cpp - Uniquing Hash Set --------------*- C++ -*-===// 266458Sdfr// 396912Smarcel// The LLVM Compiler Infrastructure 496912Smarcel// 5139790Simp// This file is distributed under the University of Illinois Open Source 666458Sdfr// License. See LICENSE.TXT for details. 766458Sdfr// 866458Sdfr//===----------------------------------------------------------------------===// 966458Sdfr// 1066458Sdfr// This file implements a hash set that can be used to remove duplication of 1166458Sdfr// nodes in a graph. This code was originally created by Chris Lattner for use 1266458Sdfr// with SelectionDAGCSEMap, but was isolated to provide use across the llvm code 1366458Sdfr// set. 1466458Sdfr// 1566458Sdfr//===----------------------------------------------------------------------===// 1666458Sdfr 1766458Sdfr#include "llvm/ADT/FoldingSet.h" 1866458Sdfr#include "llvm/Support/Allocator.h" 1966458Sdfr#include "llvm/Support/ErrorHandling.h" 2066458Sdfr#include "llvm/Support/MathExtras.h" 2166458Sdfr#include "llvm/Support/Host.h" 2266458Sdfr#include <cassert> 2366458Sdfr#include <cstring> 2466458Sdfrusing namespace llvm; 2566458Sdfr 2666458Sdfr//===----------------------------------------------------------------------===// 2766458Sdfr// FoldingSetNodeIDRef Implementation 2866458Sdfr 2966458Sdfr/// ComputeHash - Compute a strong hash value for this FoldingSetNodeIDRef, 3066458Sdfr/// used to lookup the node in the FoldingSetImpl. 3166458Sdfrunsigned FoldingSetNodeIDRef::ComputeHash() const { 3266458Sdfr // This is adapted from SuperFastHash by Paul Hsieh. 3366458Sdfr unsigned Hash = static_cast<unsigned>(Size); 3466458Sdfr for (const unsigned *BP = Data, *E = BP+Size; BP != E; ++BP) { 3566458Sdfr unsigned Data = *BP; 3666458Sdfr Hash += Data & 0xFFFF; 3766458Sdfr unsigned Tmp = ((Data >> 16) << 11) ^ Hash; 3866458Sdfr Hash = (Hash << 16) ^ Tmp; 3966458Sdfr Hash += Hash >> 11; 4066458Sdfr } 4166458Sdfr 4266458Sdfr // Force "avalanching" of final 127 bits. 4366458Sdfr Hash ^= Hash << 3; 4496912Smarcel Hash += Hash >> 5; 4566458Sdfr Hash ^= Hash << 4; 4666458Sdfr Hash += Hash >> 17; 47170033Salc Hash ^= Hash << 25; 48170033Salc Hash += Hash >> 6; 4966458Sdfr return Hash; 50115084Smarcel} 5166458Sdfr 5266458Sdfrbool FoldingSetNodeIDRef::operator==(FoldingSetNodeIDRef RHS) const { 5366458Sdfr if (Size != RHS.Size) return false; 5466458Sdfr return memcmp(Data, RHS.Data, Size*sizeof(*Data)) == 0; 5566458Sdfr} 5666458Sdfr 5766458Sdfr//===----------------------------------------------------------------------===// 5866458Sdfr// FoldingSetNodeID Implementation 5966458Sdfr 6066458Sdfr/// Add* - Add various data types to Bit data. 6166458Sdfr/// 6266458Sdfrvoid FoldingSetNodeID::AddPointer(const void *Ptr) { 6366458Sdfr // Note: this adds pointers to the hash using sizes and endianness that 6466458Sdfr // depend on the host. It doesn't matter however, because hashing on 6566458Sdfr // pointer values in inherently unstable. Nothing should depend on the 6666458Sdfr // ordering of nodes in the folding set. 6766458Sdfr Bits.append(reinterpret_cast<unsigned *>(&Ptr), 6892670Speter reinterpret_cast<unsigned *>(&Ptr+1)); 6966458Sdfr} 7066458Sdfrvoid FoldingSetNodeID::AddInteger(signed I) { 7166458Sdfr Bits.push_back(I); 7266458Sdfr} 7366458Sdfrvoid FoldingSetNodeID::AddInteger(unsigned I) { 7466458Sdfr Bits.push_back(I); 7566458Sdfr} 7666458Sdfrvoid FoldingSetNodeID::AddInteger(long I) { 7766458Sdfr AddInteger((unsigned long)I); 7866458Sdfr} 7966458Sdfrvoid FoldingSetNodeID::AddInteger(unsigned long I) { 8066458Sdfr if (sizeof(long) == sizeof(int)) 8166458Sdfr AddInteger(unsigned(I)); 8266458Sdfr else if (sizeof(long) == sizeof(long long)) { 8366458Sdfr AddInteger((unsigned long long)I); 8466458Sdfr } else { 8566458Sdfr llvm_unreachable("unexpected sizeof(long)"); 8666458Sdfr } 8766458Sdfr} 8866458Sdfrvoid FoldingSetNodeID::AddInteger(long long I) { 8966458Sdfr AddInteger((unsigned long long)I); 9066458Sdfr} 9166458Sdfrvoid FoldingSetNodeID::AddInteger(unsigned long long I) { 9266458Sdfr AddInteger(unsigned(I)); 9366458Sdfr if ((uint64_t)(unsigned)I != I) 9466458Sdfr Bits.push_back(unsigned(I >> 32)); 9566458Sdfr} 9666458Sdfr 9766458Sdfrvoid FoldingSetNodeID::AddString(StringRef String) { 9866458Sdfr unsigned Size = String.size(); 9966458Sdfr Bits.push_back(Size); 10066458Sdfr if (!Size) return; 10166458Sdfr 102150008Salc unsigned Units = Size / 4; 10366458Sdfr unsigned Pos = 0; 10466458Sdfr const unsigned *Base = (const unsigned*) String.data(); 10566458Sdfr 10666458Sdfr // If the string is aligned do a bulk transfer. 10766458Sdfr if (!((intptr_t)Base & 3)) { 10866458Sdfr Bits.append(Base, Base + Units); 109106486Smarcel Pos = (Units + 1) * 4; 110106486Smarcel } else { 111106486Smarcel // Otherwise do it the hard way. 112106486Smarcel // To be compatible with above bulk transfer, we need to take endianness 113106486Smarcel // into account. 114169291Salc if (sys::isBigEndianHost()) { 115169291Salc for (Pos += 4; Pos <= Size; Pos += 4) { 116169291Salc unsigned V = ((unsigned char)String[Pos - 4] << 24) | 117169291Salc ((unsigned char)String[Pos - 3] << 16) | 118169291Salc ((unsigned char)String[Pos - 2] << 8) | 119170519Salc (unsigned char)String[Pos - 1]; 120170519Salc Bits.push_back(V); 121170519Salc } 122170519Salc } else { 123170519Salc assert(sys::isLittleEndianHost() && "Unexpected host endianness"); 124170519Salc for (Pos += 4; Pos <= Size; Pos += 4) { 125172317Salc unsigned V = ((unsigned char)String[Pos - 1] << 24) | 126170519Salc ((unsigned char)String[Pos - 2] << 16) | 127170519Salc ((unsigned char)String[Pos - 3] << 8) | 128170519Salc (unsigned char)String[Pos - 4]; 129170519Salc Bits.push_back(V); 130172317Salc } 131172317Salc } 132170519Salc } 133170519Salc 134170519Salc // With the leftover bits. 135170519Salc unsigned V = 0; 136170519Salc // Pos will have overshot size by 4 - #bytes left over. 137170519Salc // No need to take endianness into account here - this is always executed. 138170519Salc switch (Pos - Size) { 139170519Salc case 1: V = (V << 8) | (unsigned char)String[Size - 3]; // Fall thru. 140170519Salc case 2: V = (V << 8) | (unsigned char)String[Size - 2]; // Fall thru. 141170519Salc case 3: V = (V << 8) | (unsigned char)String[Size - 1]; break; 142170519Salc default: return; // Nothing left. 143170519Salc } 144170519Salc 145170519Salc Bits.push_back(V); 146170519Salc} 147170519Salc 14896912Smarcel// AddNodeID - Adds the Bit data of another ID to *this. 14996912Smarcelvoid FoldingSetNodeID::AddNodeID(const FoldingSetNodeID &ID) { 15096912Smarcel Bits.append(ID.Bits.begin(), ID.Bits.end()); 15196912Smarcel} 15296912Smarcel 15396912Smarcel/// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used to 15496912Smarcel/// lookup the node in the FoldingSetImpl. 15596912Smarcelunsigned FoldingSetNodeID::ComputeHash() const { 15696912Smarcel return FoldingSetNodeIDRef(Bits.data(), Bits.size()).ComputeHash(); 157119906Smarcel} 158119906Smarcel 159119906Smarcel/// operator== - Used to compare two nodes to each other. 160119906Smarcel/// 161119906Smarcelbool FoldingSetNodeID::operator==(const FoldingSetNodeID &RHS)const{ 162119906Smarcel return *this == FoldingSetNodeIDRef(RHS.Bits.data(), RHS.Bits.size()); 163119906Smarcel} 164119906Smarcel 165119906Smarcel/// operator== - Used to compare two nodes to each other. 166119906Smarcel/// 167121268Smarcelbool FoldingSetNodeID::operator==(FoldingSetNodeIDRef RHS) const { 168121268Smarcel return FoldingSetNodeIDRef(Bits.data(), Bits.size()) == RHS; 169119906Smarcel} 17066458Sdfr 17166458Sdfr/// Intern - Copy this node's data to a memory region allocated from the 17266458Sdfr/// given allocator and return a FoldingSetNodeIDRef describing the 17366458Sdfr/// interned data. 17466458SdfrFoldingSetNodeIDRef 175115084SmarcelFoldingSetNodeID::Intern(BumpPtrAllocator &Allocator) const { 176115084Smarcel unsigned *New = Allocator.Allocate<unsigned>(Bits.size()); 177115084Smarcel std::uninitialized_copy(Bits.begin(), Bits.end(), New); 178115084Smarcel return FoldingSetNodeIDRef(New, Bits.size()); 17966458Sdfr} 18066458Sdfr 181115084Smarcel//===----------------------------------------------------------------------===// 18296912Smarcel/// Helper functions for FoldingSetImpl. 18366458Sdfr 18466458Sdfr/// GetNextPtr - In order to save space, each bucket is a 18566458Sdfr/// singly-linked-list. In order to make deletion more efficient, we make 18666458Sdfr/// the list circular, so we can delete a node without computing its hash. 18766458Sdfr/// The problem with this is that the start of the hash buckets are not 18866458Sdfr/// Nodes. If NextInBucketPtr is a bucket pointer, this method returns null: 18966458Sdfr/// use GetBucketPtr when this happens. 190168920Ssepotvinstatic FoldingSetImpl::Node *GetNextPtr(void *NextInBucketPtr) { 191168920Ssepotvin // The low bit is set if this is the pointer back to the bucket. 19266458Sdfr if (reinterpret_cast<intptr_t>(NextInBucketPtr) & 1) 19366458Sdfr return 0; 19466458Sdfr 19566458Sdfr return static_cast<FoldingSetImpl::Node*>(NextInBucketPtr); 19666458Sdfr} 19766458Sdfr 19866458Sdfr 19966458Sdfr/// testing. 20066458Sdfrstatic void **GetBucketPtr(void *NextInBucketPtr) { 20166458Sdfr intptr_t Ptr = reinterpret_cast<intptr_t>(NextInBucketPtr); 20266458Sdfr assert((Ptr & 1) && "Not a bucket pointer"); 20396912Smarcel return reinterpret_cast<void**>(Ptr & ~intptr_t(1)); 204} 205 206/// GetBucketFor - Hash the specified node ID and return the hash bucket for 207/// the specified ID. 208static void **GetBucketFor(unsigned Hash, void **Buckets, unsigned NumBuckets) { 209 // NumBuckets is always a power of 2. 210 unsigned BucketNum = Hash & (NumBuckets-1); 211 return Buckets + BucketNum; 212} 213 214/// AllocateBuckets - Allocated initialized bucket memory. 215static void **AllocateBuckets(unsigned NumBuckets) { 216 void **Buckets = static_cast<void**>(calloc(NumBuckets+1, sizeof(void*))); 217 // Set the very last bucket to be a non-null "pointer". 218 Buckets[NumBuckets] = reinterpret_cast<void*>(-1); 219 return Buckets; 220} 221 222//===----------------------------------------------------------------------===// 223// FoldingSetImpl Implementation 224 225FoldingSetImpl::FoldingSetImpl(unsigned Log2InitSize) { 226 assert(5 < Log2InitSize && Log2InitSize < 32 && 227 "Initial hash table size out of range"); 228 NumBuckets = 1 << Log2InitSize; 229 Buckets = AllocateBuckets(NumBuckets); 230 NumNodes = 0; 231} 232FoldingSetImpl::~FoldingSetImpl() { 233 free(Buckets); 234} 235void FoldingSetImpl::clear() { 236 // Set all but the last bucket to null pointers. 237 memset(Buckets, 0, NumBuckets*sizeof(void*)); 238 239 // Set the very last bucket to be a non-null "pointer". 240 Buckets[NumBuckets] = reinterpret_cast<void*>(-1); 241 242 // Reset the node count to zero. 243 NumNodes = 0; 244} 245 246/// GrowHashTable - Double the size of the hash table and rehash everything. 247/// 248void FoldingSetImpl::GrowHashTable() { 249 void **OldBuckets = Buckets; 250 unsigned OldNumBuckets = NumBuckets; 251 NumBuckets <<= 1; 252 253 // Clear out new buckets. 254 Buckets = AllocateBuckets(NumBuckets); 255 NumNodes = 0; 256 257 // Walk the old buckets, rehashing nodes into their new place. 258 FoldingSetNodeID TempID; 259 for (unsigned i = 0; i != OldNumBuckets; ++i) { 260 void *Probe = OldBuckets[i]; 261 if (!Probe) continue; 262 while (Node *NodeInBucket = GetNextPtr(Probe)) { 263 // Figure out the next link, remove NodeInBucket from the old link. 264 Probe = NodeInBucket->getNextInBucket(); 265 NodeInBucket->SetNextInBucket(0); 266 267 // Insert the node into the new bucket, after recomputing the hash. 268 InsertNode(NodeInBucket, 269 GetBucketFor(ComputeNodeHash(NodeInBucket, TempID), 270 Buckets, NumBuckets)); 271 TempID.clear(); 272 } 273 } 274 275 free(OldBuckets); 276} 277 278/// FindNodeOrInsertPos - Look up the node specified by ID. If it exists, 279/// return it. If not, return the insertion token that will make insertion 280/// faster. 281FoldingSetImpl::Node 282*FoldingSetImpl::FindNodeOrInsertPos(const FoldingSetNodeID &ID, 283 void *&InsertPos) { 284 285 void **Bucket = GetBucketFor(ID.ComputeHash(), Buckets, NumBuckets); 286 void *Probe = *Bucket; 287 288 InsertPos = 0; 289 290 FoldingSetNodeID TempID; 291 while (Node *NodeInBucket = GetNextPtr(Probe)) { 292 if (NodeEquals(NodeInBucket, ID, TempID)) 293 return NodeInBucket; 294 TempID.clear(); 295 296 Probe = NodeInBucket->getNextInBucket(); 297 } 298 299 // Didn't find the node, return null with the bucket as the InsertPos. 300 InsertPos = Bucket; 301 return 0; 302} 303 304/// InsertNode - Insert the specified node into the folding set, knowing that it 305/// is not already in the map. InsertPos must be obtained from 306/// FindNodeOrInsertPos. 307void FoldingSetImpl::InsertNode(Node *N, void *InsertPos) { 308 assert(N->getNextInBucket() == 0); 309 // Do we need to grow the hashtable? 310 if (NumNodes+1 > NumBuckets*2) { 311 GrowHashTable(); 312 FoldingSetNodeID TempID; 313 InsertPos = GetBucketFor(ComputeNodeHash(N, TempID), Buckets, NumBuckets); 314 } 315 316 ++NumNodes; 317 318 /// The insert position is actually a bucket pointer. 319 void **Bucket = static_cast<void**>(InsertPos); 320 321 void *Next = *Bucket; 322 323 // If this is the first insertion into this bucket, its next pointer will be 324 // null. Pretend as if it pointed to itself, setting the low bit to indicate 325 // that it is a pointer to the bucket. 326 if (Next == 0) 327 Next = reinterpret_cast<void*>(reinterpret_cast<intptr_t>(Bucket)|1); 328 329 // Set the node's next pointer, and make the bucket point to the node. 330 N->SetNextInBucket(Next); 331 *Bucket = N; 332} 333 334/// RemoveNode - Remove a node from the folding set, returning true if one was 335/// removed or false if the node was not in the folding set. 336bool FoldingSetImpl::RemoveNode(Node *N) { 337 // Because each bucket is a circular list, we don't need to compute N's hash 338 // to remove it. 339 void *Ptr = N->getNextInBucket(); 340 if (Ptr == 0) return false; // Not in folding set. 341 342 --NumNodes; 343 N->SetNextInBucket(0); 344 345 // Remember what N originally pointed to, either a bucket or another node. 346 void *NodeNextPtr = Ptr; 347 348 // Chase around the list until we find the node (or bucket) which points to N. 349 while (true) { 350 if (Node *NodeInBucket = GetNextPtr(Ptr)) { 351 // Advance pointer. 352 Ptr = NodeInBucket->getNextInBucket(); 353 354 // We found a node that points to N, change it to point to N's next node, 355 // removing N from the list. 356 if (Ptr == N) { 357 NodeInBucket->SetNextInBucket(NodeNextPtr); 358 return true; 359 } 360 } else { 361 void **Bucket = GetBucketPtr(Ptr); 362 Ptr = *Bucket; 363 364 // If we found that the bucket points to N, update the bucket to point to 365 // whatever is next. 366 if (Ptr == N) { 367 *Bucket = NodeNextPtr; 368 return true; 369 } 370 } 371 } 372} 373 374/// GetOrInsertNode - If there is an existing simple Node exactly 375/// equal to the specified node, return it. Otherwise, insert 'N' and it 376/// instead. 377FoldingSetImpl::Node *FoldingSetImpl::GetOrInsertNode(FoldingSetImpl::Node *N) { 378 FoldingSetNodeID ID; 379 GetNodeProfile(N, ID); 380 void *IP; 381 if (Node *E = FindNodeOrInsertPos(ID, IP)) 382 return E; 383 InsertNode(N, IP); 384 return N; 385} 386 387//===----------------------------------------------------------------------===// 388// FoldingSetIteratorImpl Implementation 389 390FoldingSetIteratorImpl::FoldingSetIteratorImpl(void **Bucket) { 391 // Skip to the first non-null non-self-cycle bucket. 392 while (*Bucket != reinterpret_cast<void*>(-1) && 393 (*Bucket == 0 || GetNextPtr(*Bucket) == 0)) 394 ++Bucket; 395 396 NodePtr = static_cast<FoldingSetNode*>(*Bucket); 397} 398 399void FoldingSetIteratorImpl::advance() { 400 // If there is another link within this bucket, go to it. 401 void *Probe = NodePtr->getNextInBucket(); 402 403 if (FoldingSetNode *NextNodeInBucket = GetNextPtr(Probe)) 404 NodePtr = NextNodeInBucket; 405 else { 406 // Otherwise, this is the last link in this bucket. 407 void **Bucket = GetBucketPtr(Probe); 408 409 // Skip to the next non-null non-self-cycle bucket. 410 do { 411 ++Bucket; 412 } while (*Bucket != reinterpret_cast<void*>(-1) && 413 (*Bucket == 0 || GetNextPtr(*Bucket) == 0)); 414 415 NodePtr = static_cast<FoldingSetNode*>(*Bucket); 416 } 417} 418 419//===----------------------------------------------------------------------===// 420// FoldingSetBucketIteratorImpl Implementation 421 422FoldingSetBucketIteratorImpl::FoldingSetBucketIteratorImpl(void **Bucket) { 423 Ptr = (*Bucket == 0 || GetNextPtr(*Bucket) == 0) ? (void*) Bucket : *Bucket; 424} 425