AliasSetTracker.h revision 235fc57ef2ed0a3c43a6e2d77b7c13f96a6f8036
1//===- llvm/Analysis/AliasSetTracker.h - Build Alias Sets -------*- 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 defines two classes: AliasSetTracker and AliasSet. These interface 11// are used to classify a collection of pointer references into a maximal number 12// of disjoint sets. Each AliasSet object constructed by the AliasSetTracker 13// object refers to memory disjoint from the other sets. 14// 15//===----------------------------------------------------------------------===// 16 17#ifndef LLVM_ANALYSIS_ALIASSETTRACKER_H 18#define LLVM_ANALYSIS_ALIASSETTRACKER_H 19 20#include "llvm/Support/CallSite.h" 21#include "llvm/Support/Streams.h" 22#include "llvm/ADT/iterator" 23#include "llvm/ADT/hash_map" 24#include "llvm/ADT/ilist" 25 26namespace llvm { 27 28class AliasAnalysis; 29class LoadInst; 30class StoreInst; 31class FreeInst; 32class VAArgInst; 33class AliasSetTracker; 34class AliasSet; 35 36class AliasSet { 37 friend class AliasSetTracker; 38 39 class PointerRec; 40 typedef std::pair<Value* const, PointerRec> HashNodePair; 41 42 class PointerRec { 43 HashNodePair **PrevInList, *NextInList; 44 AliasSet *AS; 45 unsigned Size; 46 public: 47 PointerRec() : PrevInList(0), NextInList(0), AS(0), Size(0) {} 48 49 HashNodePair *getNext() const { return NextInList; } 50 bool hasAliasSet() const { return AS != 0; } 51 52 HashNodePair** setPrevInList(HashNodePair **PIL) { 53 PrevInList = PIL; 54 return &NextInList; 55 } 56 57 void updateSize(unsigned NewSize) { 58 if (NewSize > Size) Size = NewSize; 59 } 60 61 unsigned getSize() const { return Size; } 62 63 AliasSet *getAliasSet(AliasSetTracker &AST) { 64 assert(AS && "No AliasSet yet!"); 65 if (AS->Forward) { 66 AliasSet *OldAS = AS; 67 AS = OldAS->getForwardedTarget(AST); 68 AS->addRef(); 69 OldAS->dropRef(AST); 70 } 71 return AS; 72 } 73 74 void setAliasSet(AliasSet *as) { 75 assert(AS == 0 && "Already have an alias set!"); 76 AS = as; 77 } 78 79 void removeFromList() { 80 if (NextInList) NextInList->second.PrevInList = PrevInList; 81 *PrevInList = NextInList; 82 if (AS->PtrListEnd == &NextInList) { 83 AS->PtrListEnd = PrevInList; 84 assert(*AS->PtrListEnd == 0 && "List not terminated right!"); 85 } 86 } 87 }; 88 89 HashNodePair *PtrList, **PtrListEnd; // Doubly linked list of nodes 90 AliasSet *Forward; // Forwarding pointer 91 AliasSet *Next, *Prev; // Doubly linked list of AliasSets 92 93 std::vector<CallSite> CallSites; // All calls & invokes in this node 94 95 // RefCount - Number of nodes pointing to this AliasSet plus the number of 96 // AliasSets forwarding to it. 97 unsigned RefCount : 28; 98 99 /// AccessType - Keep track of whether this alias set merely refers to the 100 /// locations of memory, whether it modifies the memory, or whether it does 101 /// both. The lattice goes from "NoModRef" to either Refs or Mods, then to 102 /// ModRef as necessary. 103 /// 104 enum AccessType { 105 NoModRef = 0, Refs = 1, // Ref = bit 1 106 Mods = 2, ModRef = 3 // Mod = bit 2 107 }; 108 unsigned AccessTy : 2; 109 110 /// AliasType - Keep track the relationships between the pointers in the set. 111 /// Lattice goes from MustAlias to MayAlias. 112 /// 113 enum AliasType { 114 MustAlias = 0, MayAlias = 1 115 }; 116 unsigned AliasTy : 1; 117 118 // Volatile - True if this alias set contains volatile loads or stores. 119 bool Volatile : 1; 120 121 friend struct ilist_traits<AliasSet>; 122 AliasSet *getPrev() const { return Prev; } 123 AliasSet *getNext() const { return Next; } 124 void setPrev(AliasSet *P) { Prev = P; } 125 void setNext(AliasSet *N) { Next = N; } 126 127 void addRef() { ++RefCount; } 128 void dropRef(AliasSetTracker &AST) { 129 assert(RefCount >= 1 && "Invalid reference count detected!"); 130 if (--RefCount == 0) 131 removeFromTracker(AST); 132 } 133 134public: 135 /// Accessors... 136 bool isRef() const { return AccessTy & Refs; } 137 bool isMod() const { return AccessTy & Mods; } 138 bool isMustAlias() const { return AliasTy == MustAlias; } 139 bool isMayAlias() const { return AliasTy == MayAlias; } 140 141 // isVolatile - Return true if this alias set contains volatile loads or 142 // stores. 143 bool isVolatile() const { return Volatile; } 144 145 /// isForwardingAliasSet - Return true if this alias set should be ignored as 146 /// part of the AliasSetTracker object. 147 bool isForwardingAliasSet() const { return Forward; } 148 149 /// mergeSetIn - Merge the specified alias set into this alias set... 150 /// 151 void mergeSetIn(AliasSet &AS, AliasSetTracker &AST); 152 153 // Alias Set iteration - Allow access to all of the pointer which are part of 154 // this alias set... 155 class iterator; 156 iterator begin() const { return iterator(PtrList); } 157 iterator end() const { return iterator(); } 158 bool empty() const { return PtrList == 0; } 159 160 void print(std::ostream &OS) const; 161 void print(std::ostream *OS) const { if (OS) print(*OS); } 162 void dump() const; 163 164 /// Define an iterator for alias sets... this is just a forward iterator. 165 class iterator : public forward_iterator<HashNodePair, ptrdiff_t> { 166 HashNodePair *CurNode; 167 public: 168 explicit iterator(HashNodePair *CN = 0) : CurNode(CN) {} 169 170 bool operator==(const iterator& x) const { 171 return CurNode == x.CurNode; 172 } 173 bool operator!=(const iterator& x) const { return !operator==(x); } 174 175 const iterator &operator=(const iterator &I) { 176 CurNode = I.CurNode; 177 return *this; 178 } 179 180 value_type &operator*() const { 181 assert(CurNode && "Dereferencing AliasSet.end()!"); 182 return *CurNode; 183 } 184 value_type *operator->() const { return &operator*(); } 185 186 Value *getPointer() const { return CurNode->first; } 187 unsigned getSize() const { return CurNode->second.getSize(); } 188 189 iterator& operator++() { // Preincrement 190 assert(CurNode && "Advancing past AliasSet.end()!"); 191 CurNode = CurNode->second.getNext(); 192 return *this; 193 } 194 iterator operator++(int) { // Postincrement 195 iterator tmp = *this; ++*this; return tmp; 196 } 197 }; 198 199private: 200 // Can only be created by AliasSetTracker 201 AliasSet() : PtrList(0), PtrListEnd(&PtrList), Forward(0), RefCount(0), 202 AccessTy(NoModRef), AliasTy(MustAlias), Volatile(false) { 203 } 204 205 AliasSet(const AliasSet &AS) { 206 assert(0 && "Copy ctor called!?!?!"); 207 abort(); 208 } 209 210 HashNodePair *getSomePointer() const { 211 return PtrList; 212 } 213 214 /// getForwardedTarget - Return the real alias set this represents. If this 215 /// has been merged with another set and is forwarding, return the ultimate 216 /// destination set. This also implements the union-find collapsing as well. 217 AliasSet *getForwardedTarget(AliasSetTracker &AST) { 218 if (!Forward) return this; 219 220 AliasSet *Dest = Forward->getForwardedTarget(AST); 221 if (Dest != Forward) { 222 Dest->addRef(); 223 Forward->dropRef(AST); 224 Forward = Dest; 225 } 226 return Dest; 227 } 228 229 void removeFromTracker(AliasSetTracker &AST); 230 231 void addPointer(AliasSetTracker &AST, HashNodePair &Entry, unsigned Size, 232 bool KnownMustAlias = false); 233 void addCallSite(CallSite CS, AliasAnalysis &AA); 234 void removeCallSite(CallSite CS) { 235 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) 236 if (CallSites[i].getInstruction() == CS.getInstruction()) { 237 CallSites[i] = CallSites.back(); 238 CallSites.pop_back(); 239 } 240 } 241 void setVolatile() { Volatile = true; } 242 243 /// aliasesPointer - Return true if the specified pointer "may" (or must) 244 /// alias one of the members in the set. 245 /// 246 bool aliasesPointer(const Value *Ptr, unsigned Size, AliasAnalysis &AA) const; 247 bool aliasesCallSite(CallSite CS, AliasAnalysis &AA) const; 248}; 249 250inline std::ostream& operator<<(std::ostream &OS, const AliasSet &AS) { 251 AS.print(OS); 252 return OS; 253} 254 255 256class AliasSetTracker { 257 AliasAnalysis &AA; 258 ilist<AliasSet> AliasSets; 259 260 // Map from pointers to their node 261 hash_map<Value*, AliasSet::PointerRec> PointerMap; 262public: 263 /// AliasSetTracker ctor - Create an empty collection of AliasSets, and use 264 /// the specified alias analysis object to disambiguate load and store 265 /// addresses. 266 explicit AliasSetTracker(AliasAnalysis &aa) : AA(aa) {} 267 ~AliasSetTracker() { clear(); } 268 269 /// add methods - These methods are used to add different types of 270 /// instructions to the alias sets. Adding a new instruction can result in 271 /// one of three actions happening: 272 /// 273 /// 1. If the instruction doesn't alias any other sets, create a new set. 274 /// 2. If the instruction aliases exactly one set, add it to the set 275 /// 3. If the instruction aliases multiple sets, merge the sets, and add 276 /// the instruction to the result. 277 /// 278 /// These methods return true if inserting the instruction resulted in the 279 /// addition of a new alias set (i.e., the pointer did not alias anything). 280 /// 281 bool add(Value *Ptr, unsigned Size); // Add a location 282 bool add(LoadInst *LI); 283 bool add(StoreInst *SI); 284 bool add(FreeInst *FI); 285 bool add(VAArgInst *VAAI); 286 bool add(CallSite CS); // Call/Invoke instructions 287 bool add(CallInst *CI) { return add(CallSite(CI)); } 288 bool add(InvokeInst *II) { return add(CallSite(II)); } 289 bool add(Instruction *I); // Dispatch to one of the other add methods... 290 void add(BasicBlock &BB); // Add all instructions in basic block 291 void add(const AliasSetTracker &AST); // Add alias relations from another AST 292 293 /// remove methods - These methods are used to remove all entries that might 294 /// be aliased by the specified instruction. These methods return true if any 295 /// alias sets were eliminated. 296 bool remove(Value *Ptr, unsigned Size); // Remove a location 297 bool remove(LoadInst *LI); 298 bool remove(StoreInst *SI); 299 bool remove(FreeInst *FI); 300 bool remove(VAArgInst *VAAI); 301 bool remove(CallSite CS); 302 bool remove(CallInst *CI) { return remove(CallSite(CI)); } 303 bool remove(InvokeInst *II) { return remove(CallSite(II)); } 304 bool remove(Instruction *I); 305 void remove(AliasSet &AS); 306 307 void clear() { 308 PointerMap.clear(); 309 AliasSets.clear(); 310 } 311 312 /// getAliasSets - Return the alias sets that are active. 313 /// 314 const ilist<AliasSet> &getAliasSets() const { return AliasSets; } 315 316 /// getAliasSetForPointer - Return the alias set that the specified pointer 317 /// lives in. If the New argument is non-null, this method sets the value to 318 /// true if a new alias set is created to contain the pointer (because the 319 /// pointer didn't alias anything). 320 AliasSet &getAliasSetForPointer(Value *P, unsigned Size, bool *New = 0); 321 322 /// getAliasSetForPointerIfExists - Return the alias set containing the 323 /// location specified if one exists, otherwise return null. 324 AliasSet *getAliasSetForPointerIfExists(Value *P, unsigned Size) { 325 return findAliasSetForPointer(P, Size); 326 } 327 328 /// containsPointer - Return true if the specified location is represented by 329 /// this alias set, false otherwise. This does not modify the AST object or 330 /// alias sets. 331 bool containsPointer(Value *P, unsigned Size) const; 332 333 /// getAliasAnalysis - Return the underlying alias analysis object used by 334 /// this tracker. 335 AliasAnalysis &getAliasAnalysis() const { return AA; } 336 337 /// deleteValue method - This method is used to remove a pointer value from 338 /// the AliasSetTracker entirely. It should be used when an instruction is 339 /// deleted from the program to update the AST. If you don't use this, you 340 /// would have dangling pointers to deleted instructions. 341 /// 342 void deleteValue(Value *PtrVal); 343 344 /// copyValue - This method should be used whenever a preexisting value in the 345 /// program is copied or cloned, introducing a new value. Note that it is ok 346 /// for clients that use this method to introduce the same value multiple 347 /// times: if the tracker already knows about a value, it will ignore the 348 /// request. 349 /// 350 void copyValue(Value *From, Value *To); 351 352 353 typedef ilist<AliasSet>::iterator iterator; 354 typedef ilist<AliasSet>::const_iterator const_iterator; 355 356 const_iterator begin() const { return AliasSets.begin(); } 357 const_iterator end() const { return AliasSets.end(); } 358 359 iterator begin() { return AliasSets.begin(); } 360 iterator end() { return AliasSets.end(); } 361 362 void print(std::ostream &OS) const; 363 void print(std::ostream *OS) const { if (OS) print(*OS); } 364 void dump() const; 365 366private: 367 friend class AliasSet; 368 void removeAliasSet(AliasSet *AS); 369 370 AliasSet::HashNodePair &getEntryFor(Value *V) { 371 // Standard operator[], except that it returns the whole pair, not just 372 // ->second. 373 return *PointerMap.insert(AliasSet::HashNodePair(V, 374 AliasSet::PointerRec())).first; 375 } 376 377 AliasSet &addPointer(Value *P, unsigned Size, AliasSet::AccessType E, 378 bool &NewSet) { 379 NewSet = false; 380 AliasSet &AS = getAliasSetForPointer(P, Size, &NewSet); 381 AS.AccessTy |= E; 382 return AS; 383 } 384 AliasSet *findAliasSetForPointer(const Value *Ptr, unsigned Size); 385 386 AliasSet *findAliasSetForCallSite(CallSite CS); 387}; 388 389inline std::ostream& operator<<(std::ostream &OS, const AliasSetTracker &AST) { 390 AST.print(OS); 391 return OS; 392} 393 394} // End llvm namespace 395 396#endif 397