AliasSetTracker.h revision 688ed8583eaa1544e8e53b039b2b8284d2e9268a
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/ADT/DenseMap.h" 22#include "llvm/ADT/iterator.h" 23#include "llvm/ADT/ilist.h" 24#include "llvm/ADT/ilist_node.h" 25#include <vector> 26 27namespace llvm { 28 29class AliasAnalysis; 30class LoadInst; 31class StoreInst; 32class FreeInst; 33class VAArgInst; 34class AliasSetTracker; 35class AliasSet; 36 37class AliasSet : public ilist_node<AliasSet> { 38 friend class AliasSetTracker; 39 40 class PointerRec { 41 Value *Val; // The pointer this record corresponds to. 42 PointerRec **PrevInList, *NextInList; 43 AliasSet *AS; 44 unsigned Size; 45 public: 46 PointerRec(Value *V) 47 : Val(V), PrevInList(0), NextInList(0), AS(0), Size(0) {} 48 49 Value *getValue() const { return Val; } 50 51 PointerRec *getNext() const { return NextInList; } 52 bool hasAliasSet() const { return AS != 0; } 53 54 PointerRec** setPrevInList(PointerRec **PIL) { 55 PrevInList = PIL; 56 return &NextInList; 57 } 58 59 void updateSize(unsigned NewSize) { 60 if (NewSize > Size) Size = NewSize; 61 } 62 63 unsigned getSize() const { return Size; } 64 65 AliasSet *getAliasSet(AliasSetTracker &AST) { 66 assert(AS && "No AliasSet yet!"); 67 if (AS->Forward) { 68 AliasSet *OldAS = AS; 69 AS = OldAS->getForwardedTarget(AST); 70 AS->addRef(); 71 OldAS->dropRef(AST); 72 } 73 return AS; 74 } 75 76 void setAliasSet(AliasSet *as) { 77 assert(AS == 0 && "Already have an alias set!"); 78 AS = as; 79 } 80 81 void eraseFromList() { 82 if (NextInList) NextInList->PrevInList = PrevInList; 83 *PrevInList = NextInList; 84 if (AS->PtrListEnd == &NextInList) { 85 AS->PtrListEnd = PrevInList; 86 assert(*AS->PtrListEnd == 0 && "List not terminated right!"); 87 } 88 delete this; 89 } 90 }; 91 92 PointerRec *PtrList, **PtrListEnd; // Doubly linked list of nodes. 93 AliasSet *Forward; // Forwarding pointer. 94 AliasSet *Next, *Prev; // Doubly linked list of AliasSets. 95 96 std::vector<CallSite> CallSites; // All calls & invokes in this alias set. 97 98 // RefCount - Number of nodes pointing to this AliasSet plus the number of 99 // AliasSets forwarding to it. 100 unsigned RefCount : 28; 101 102 /// AccessType - Keep track of whether this alias set merely refers to the 103 /// locations of memory, whether it modifies the memory, or whether it does 104 /// both. The lattice goes from "NoModRef" to either Refs or Mods, then to 105 /// ModRef as necessary. 106 /// 107 enum AccessType { 108 NoModRef = 0, Refs = 1, // Ref = bit 1 109 Mods = 2, ModRef = 3 // Mod = bit 2 110 }; 111 unsigned AccessTy : 2; 112 113 /// AliasType - Keep track the relationships between the pointers in the set. 114 /// Lattice goes from MustAlias to MayAlias. 115 /// 116 enum AliasType { 117 MustAlias = 0, MayAlias = 1 118 }; 119 unsigned AliasTy : 1; 120 121 // Volatile - True if this alias set contains volatile loads or stores. 122 bool Volatile : 1; 123 124 void addRef() { ++RefCount; } 125 void dropRef(AliasSetTracker &AST) { 126 assert(RefCount >= 1 && "Invalid reference count detected!"); 127 if (--RefCount == 0) 128 removeFromTracker(AST); 129 } 130 131public: 132 /// Accessors... 133 bool isRef() const { return AccessTy & Refs; } 134 bool isMod() const { return AccessTy & Mods; } 135 bool isMustAlias() const { return AliasTy == MustAlias; } 136 bool isMayAlias() const { return AliasTy == MayAlias; } 137 138 // isVolatile - Return true if this alias set contains volatile loads or 139 // stores. 140 bool isVolatile() const { return Volatile; } 141 142 /// isForwardingAliasSet - Return true if this alias set should be ignored as 143 /// part of the AliasSetTracker object. 144 bool isForwardingAliasSet() const { return Forward; } 145 146 /// mergeSetIn - Merge the specified alias set into this alias set... 147 /// 148 void mergeSetIn(AliasSet &AS, AliasSetTracker &AST); 149 150 // Alias Set iteration - Allow access to all of the pointer which are part of 151 // this alias set... 152 class iterator; 153 iterator begin() const { return iterator(PtrList); } 154 iterator end() const { return iterator(); } 155 bool empty() const { return PtrList == 0; } 156 157 void print(std::ostream &OS) const; 158 void print(std::ostream *OS) const { if (OS) print(*OS); } 159 void dump() const; 160 161 /// Define an iterator for alias sets... this is just a forward iterator. 162 class iterator : public forward_iterator<PointerRec, ptrdiff_t> { 163 PointerRec *CurNode; 164 public: 165 explicit iterator(PointerRec *CN = 0) : CurNode(CN) {} 166 167 bool operator==(const iterator& x) const { 168 return CurNode == x.CurNode; 169 } 170 bool operator!=(const iterator& x) const { return !operator==(x); } 171 172 const iterator &operator=(const iterator &I) { 173 CurNode = I.CurNode; 174 return *this; 175 } 176 177 value_type &operator*() const { 178 assert(CurNode && "Dereferencing AliasSet.end()!"); 179 return *CurNode; 180 } 181 value_type *operator->() const { return &operator*(); } 182 183 Value *getPointer() const { return CurNode->getValue(); } 184 unsigned getSize() const { return CurNode->getSize(); } 185 186 iterator& operator++() { // Preincrement 187 assert(CurNode && "Advancing past AliasSet.end()!"); 188 CurNode = CurNode->getNext(); 189 return *this; 190 } 191 iterator operator++(int) { // Postincrement 192 iterator tmp = *this; ++*this; return tmp; 193 } 194 }; 195 196private: 197 // Can only be created by AliasSetTracker. Also, ilist creates one 198 // to serve as a sentinel. 199 friend struct ilist_sentinel_traits<AliasSet>; 200 AliasSet() : PtrList(0), PtrListEnd(&PtrList), Forward(0), RefCount(0), 201 AccessTy(NoModRef), AliasTy(MustAlias), Volatile(false) { 202 } 203 204 AliasSet(const AliasSet &AS); // do not implement 205 void operator=(const AliasSet &AS); // do not implement 206 207 PointerRec *getSomePointer() const { 208 return PtrList; 209 } 210 211 /// getForwardedTarget - Return the real alias set this represents. If this 212 /// has been merged with another set and is forwarding, return the ultimate 213 /// destination set. This also implements the union-find collapsing as well. 214 AliasSet *getForwardedTarget(AliasSetTracker &AST) { 215 if (!Forward) return this; 216 217 AliasSet *Dest = Forward->getForwardedTarget(AST); 218 if (Dest != Forward) { 219 Dest->addRef(); 220 Forward->dropRef(AST); 221 Forward = Dest; 222 } 223 return Dest; 224 } 225 226 void removeFromTracker(AliasSetTracker &AST); 227 228 void addPointer(AliasSetTracker &AST, PointerRec &Entry, unsigned Size, 229 bool KnownMustAlias = false); 230 void addCallSite(CallSite CS, AliasAnalysis &AA); 231 void removeCallSite(CallSite CS) { 232 for (size_t i = 0, e = CallSites.size(); i != e; ++i) 233 if (CallSites[i].getInstruction() == CS.getInstruction()) { 234 CallSites[i] = CallSites.back(); 235 CallSites.pop_back(); 236 } 237 } 238 void setVolatile() { Volatile = true; } 239 240 /// aliasesPointer - Return true if the specified pointer "may" (or must) 241 /// alias one of the members in the set. 242 /// 243 bool aliasesPointer(const Value *Ptr, unsigned Size, AliasAnalysis &AA) const; 244 bool aliasesCallSite(CallSite CS, AliasAnalysis &AA) const; 245}; 246 247inline std::ostream& operator<<(std::ostream &OS, const AliasSet &AS) { 248 AS.print(OS); 249 return OS; 250} 251 252 253class AliasSetTracker { 254 AliasAnalysis &AA; 255 ilist<AliasSet> AliasSets; 256 257 // Map from pointers to their node 258 DenseMap<Value*, AliasSet::PointerRec*> PointerMap; 259public: 260 /// AliasSetTracker ctor - Create an empty collection of AliasSets, and use 261 /// the specified alias analysis object to disambiguate load and store 262 /// addresses. 263 explicit AliasSetTracker(AliasAnalysis &aa) : AA(aa) {} 264 ~AliasSetTracker() { clear(); } 265 266 /// add methods - These methods are used to add different types of 267 /// instructions to the alias sets. Adding a new instruction can result in 268 /// one of three actions happening: 269 /// 270 /// 1. If the instruction doesn't alias any other sets, create a new set. 271 /// 2. If the instruction aliases exactly one set, add it to the set 272 /// 3. If the instruction aliases multiple sets, merge the sets, and add 273 /// the instruction to the result. 274 /// 275 /// These methods return true if inserting the instruction resulted in the 276 /// addition of a new alias set (i.e., the pointer did not alias anything). 277 /// 278 bool add(Value *Ptr, unsigned Size); // Add a location 279 bool add(LoadInst *LI); 280 bool add(StoreInst *SI); 281 bool add(FreeInst *FI); 282 bool add(VAArgInst *VAAI); 283 bool add(CallSite CS); // Call/Invoke instructions 284 bool add(CallInst *CI) { return add(CallSite(CI)); } 285 bool add(InvokeInst *II) { return add(CallSite(II)); } 286 bool add(Instruction *I); // Dispatch to one of the other add methods... 287 void add(BasicBlock &BB); // Add all instructions in basic block 288 void add(const AliasSetTracker &AST); // Add alias relations from another AST 289 290 /// remove methods - These methods are used to remove all entries that might 291 /// be aliased by the specified instruction. These methods return true if any 292 /// alias sets were eliminated. 293 bool remove(Value *Ptr, unsigned Size); // Remove a location 294 bool remove(LoadInst *LI); 295 bool remove(StoreInst *SI); 296 bool remove(FreeInst *FI); 297 bool remove(VAArgInst *VAAI); 298 bool remove(CallSite CS); 299 bool remove(CallInst *CI) { return remove(CallSite(CI)); } 300 bool remove(InvokeInst *II) { return remove(CallSite(II)); } 301 bool remove(Instruction *I); 302 void remove(AliasSet &AS); 303 304 void clear(); 305 306 /// getAliasSets - Return the alias sets that are active. 307 /// 308 const ilist<AliasSet> &getAliasSets() const { return AliasSets; } 309 310 /// getAliasSetForPointer - Return the alias set that the specified pointer 311 /// lives in. If the New argument is non-null, this method sets the value to 312 /// true if a new alias set is created to contain the pointer (because the 313 /// pointer didn't alias anything). 314 AliasSet &getAliasSetForPointer(Value *P, unsigned Size, bool *New = 0); 315 316 /// getAliasSetForPointerIfExists - Return the alias set containing the 317 /// location specified if one exists, otherwise return null. 318 AliasSet *getAliasSetForPointerIfExists(Value *P, unsigned Size) { 319 return findAliasSetForPointer(P, Size); 320 } 321 322 /// containsPointer - Return true if the specified location is represented by 323 /// this alias set, false otherwise. This does not modify the AST object or 324 /// alias sets. 325 bool containsPointer(Value *P, unsigned Size) const; 326 327 /// getAliasAnalysis - Return the underlying alias analysis object used by 328 /// this tracker. 329 AliasAnalysis &getAliasAnalysis() const { return AA; } 330 331 /// deleteValue method - This method is used to remove a pointer value from 332 /// the AliasSetTracker entirely. It should be used when an instruction is 333 /// deleted from the program to update the AST. If you don't use this, you 334 /// would have dangling pointers to deleted instructions. 335 /// 336 void deleteValue(Value *PtrVal); 337 338 /// copyValue - This method should be used whenever a preexisting value in the 339 /// program is copied or cloned, introducing a new value. Note that it is ok 340 /// for clients that use this method to introduce the same value multiple 341 /// times: if the tracker already knows about a value, it will ignore the 342 /// request. 343 /// 344 void copyValue(Value *From, Value *To); 345 346 347 typedef ilist<AliasSet>::iterator iterator; 348 typedef ilist<AliasSet>::const_iterator const_iterator; 349 350 const_iterator begin() const { return AliasSets.begin(); } 351 const_iterator end() const { return AliasSets.end(); } 352 353 iterator begin() { return AliasSets.begin(); } 354 iterator end() { return AliasSets.end(); } 355 356 void print(std::ostream &OS) const; 357 void print(std::ostream *OS) const { if (OS) print(*OS); } 358 void dump() const; 359 360private: 361 friend class AliasSet; 362 void removeAliasSet(AliasSet *AS); 363 364 // getEntryFor - Just like operator[] on the map, except that it creates an 365 // entry for the pointer if it doesn't already exist. 366 AliasSet::PointerRec &getEntryFor(Value *V) { 367 AliasSet::PointerRec *&Entry = PointerMap[V]; 368 if (Entry == 0) 369 Entry = new AliasSet::PointerRec(V); 370 return *Entry; 371 } 372 373 AliasSet &addPointer(Value *P, unsigned Size, AliasSet::AccessType E, 374 bool &NewSet) { 375 NewSet = false; 376 AliasSet &AS = getAliasSetForPointer(P, Size, &NewSet); 377 AS.AccessTy |= E; 378 return AS; 379 } 380 AliasSet *findAliasSetForPointer(const Value *Ptr, unsigned Size); 381 382 AliasSet *findAliasSetForCallSite(CallSite CS); 383}; 384 385inline std::ostream& operator<<(std::ostream &OS, const AliasSetTracker &AST) { 386 AST.print(OS); 387 return OS; 388} 389 390} // End llvm namespace 391 392#endif 393