AliasSetTracker.h revision b5b56ba9d4df47e618d4e0f9e1e09bf216733ee8
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/ValueHandle.h" 22#include "llvm/ADT/DenseMap.h" 23#include "llvm/ADT/iterator.h" 24#include "llvm/ADT/ilist.h" 25#include "llvm/ADT/ilist_node.h" 26#include <vector> 27 28namespace llvm { 29 30class AliasAnalysis; 31class LoadInst; 32class StoreInst; 33class FreeInst; 34class VAArgInst; 35class AliasSetTracker; 36class AliasSet; 37 38class AliasSet : public ilist_node<AliasSet> { 39 friend class AliasSetTracker; 40 41 class PointerRec { 42 Value *Val; // The pointer this record corresponds to. 43 PointerRec **PrevInList, *NextInList; 44 AliasSet *AS; 45 unsigned Size; 46 public: 47 PointerRec(Value *V) 48 : Val(V), PrevInList(0), NextInList(0), AS(0), Size(0) {} 49 50 Value *getValue() const { return Val; } 51 52 PointerRec *getNext() const { return NextInList; } 53 bool hasAliasSet() const { return AS != 0; } 54 55 PointerRec** setPrevInList(PointerRec **PIL) { 56 PrevInList = PIL; 57 return &NextInList; 58 } 59 60 void updateSize(unsigned NewSize) { 61 if (NewSize > Size) Size = NewSize; 62 } 63 64 unsigned getSize() const { return Size; } 65 66 AliasSet *getAliasSet(AliasSetTracker &AST) { 67 assert(AS && "No AliasSet yet!"); 68 if (AS->Forward) { 69 AliasSet *OldAS = AS; 70 AS = OldAS->getForwardedTarget(AST); 71 AS->addRef(); 72 OldAS->dropRef(AST); 73 } 74 return AS; 75 } 76 77 void setAliasSet(AliasSet *as) { 78 assert(AS == 0 && "Already have an alias set!"); 79 AS = as; 80 } 81 82 void eraseFromList() { 83 if (NextInList) NextInList->PrevInList = PrevInList; 84 *PrevInList = NextInList; 85 if (AS->PtrListEnd == &NextInList) { 86 AS->PtrListEnd = PrevInList; 87 assert(*AS->PtrListEnd == 0 && "List not terminated right!"); 88 } 89 delete this; 90 } 91 }; 92 93 PointerRec *PtrList, **PtrListEnd; // Doubly linked list of nodes. 94 AliasSet *Forward; // Forwarding pointer. 95 AliasSet *Next, *Prev; // Doubly linked list of AliasSets. 96 97 std::vector<CallSite> CallSites; // All calls & invokes in this alias set. 98 99 // RefCount - Number of nodes pointing to this AliasSet plus the number of 100 // AliasSets forwarding to it. 101 unsigned RefCount : 28; 102 103 /// AccessType - Keep track of whether this alias set merely refers to the 104 /// locations of memory, whether it modifies the memory, or whether it does 105 /// both. The lattice goes from "NoModRef" to either Refs or Mods, then to 106 /// ModRef as necessary. 107 /// 108 enum AccessType { 109 NoModRef = 0, Refs = 1, // Ref = bit 1 110 Mods = 2, ModRef = 3 // Mod = bit 2 111 }; 112 unsigned AccessTy : 2; 113 114 /// AliasType - Keep track the relationships between the pointers in the set. 115 /// Lattice goes from MustAlias to MayAlias. 116 /// 117 enum AliasType { 118 MustAlias = 0, MayAlias = 1 119 }; 120 unsigned AliasTy : 1; 121 122 // Volatile - True if this alias set contains volatile loads or stores. 123 bool Volatile : 1; 124 125 void addRef() { ++RefCount; } 126 void dropRef(AliasSetTracker &AST) { 127 assert(RefCount >= 1 && "Invalid reference count detected!"); 128 if (--RefCount == 0) 129 removeFromTracker(AST); 130 } 131 132public: 133 /// Accessors... 134 bool isRef() const { return AccessTy & Refs; } 135 bool isMod() const { return AccessTy & Mods; } 136 bool isMustAlias() const { return AliasTy == MustAlias; } 137 bool isMayAlias() const { return AliasTy == MayAlias; } 138 139 // isVolatile - Return true if this alias set contains volatile loads or 140 // stores. 141 bool isVolatile() const { return Volatile; } 142 143 /// isForwardingAliasSet - Return true if this alias set should be ignored as 144 /// part of the AliasSetTracker object. 145 bool isForwardingAliasSet() const { return Forward; } 146 147 /// mergeSetIn - Merge the specified alias set into this alias set... 148 /// 149 void mergeSetIn(AliasSet &AS, AliasSetTracker &AST); 150 151 // Alias Set iteration - Allow access to all of the pointer which are part of 152 // this alias set... 153 class iterator; 154 iterator begin() const { return iterator(PtrList); } 155 iterator end() const { return iterator(); } 156 bool empty() const { return PtrList == 0; } 157 158 void print(std::ostream &OS) const; 159 void print(std::ostream *OS) const { if (OS) print(*OS); } 160 void dump() const; 161 162 /// Define an iterator for alias sets... this is just a forward iterator. 163 class iterator : public forward_iterator<PointerRec, ptrdiff_t> { 164 PointerRec *CurNode; 165 public: 166 explicit iterator(PointerRec *CN = 0) : CurNode(CN) {} 167 168 bool operator==(const iterator& x) const { 169 return CurNode == x.CurNode; 170 } 171 bool operator!=(const iterator& x) const { return !operator==(x); } 172 173 const iterator &operator=(const iterator &I) { 174 CurNode = I.CurNode; 175 return *this; 176 } 177 178 value_type &operator*() const { 179 assert(CurNode && "Dereferencing AliasSet.end()!"); 180 return *CurNode; 181 } 182 value_type *operator->() const { return &operator*(); } 183 184 Value *getPointer() const { return CurNode->getValue(); } 185 unsigned getSize() const { return CurNode->getSize(); } 186 187 iterator& operator++() { // Preincrement 188 assert(CurNode && "Advancing past AliasSet.end()!"); 189 CurNode = CurNode->getNext(); 190 return *this; 191 } 192 iterator operator++(int) { // Postincrement 193 iterator tmp = *this; ++*this; return tmp; 194 } 195 }; 196 197private: 198 // Can only be created by AliasSetTracker. Also, ilist creates one 199 // to serve as a sentinel. 200 friend struct ilist_sentinel_traits<AliasSet>; 201 AliasSet() : PtrList(0), PtrListEnd(&PtrList), Forward(0), RefCount(0), 202 AccessTy(NoModRef), AliasTy(MustAlias), Volatile(false) { 203 } 204 205 AliasSet(const AliasSet &AS); // do not implement 206 void operator=(const AliasSet &AS); // do not implement 207 208 PointerRec *getSomePointer() const { 209 return PtrList; 210 } 211 212 /// getForwardedTarget - Return the real alias set this represents. If this 213 /// has been merged with another set and is forwarding, return the ultimate 214 /// destination set. This also implements the union-find collapsing as well. 215 AliasSet *getForwardedTarget(AliasSetTracker &AST) { 216 if (!Forward) return this; 217 218 AliasSet *Dest = Forward->getForwardedTarget(AST); 219 if (Dest != Forward) { 220 Dest->addRef(); 221 Forward->dropRef(AST); 222 Forward = Dest; 223 } 224 return Dest; 225 } 226 227 void removeFromTracker(AliasSetTracker &AST); 228 229 void addPointer(AliasSetTracker &AST, PointerRec &Entry, unsigned Size, 230 bool KnownMustAlias = false); 231 void addCallSite(CallSite CS, AliasAnalysis &AA); 232 void removeCallSite(CallSite CS) { 233 for (size_t i = 0, e = CallSites.size(); i != e; ++i) 234 if (CallSites[i].getInstruction() == CS.getInstruction()) { 235 CallSites[i] = CallSites.back(); 236 CallSites.pop_back(); 237 } 238 } 239 void setVolatile() { Volatile = true; } 240 241 /// aliasesPointer - Return true if the specified pointer "may" (or must) 242 /// alias one of the members in the set. 243 /// 244 bool aliasesPointer(const Value *Ptr, unsigned Size, AliasAnalysis &AA) const; 245 bool aliasesCallSite(CallSite CS, AliasAnalysis &AA) const; 246}; 247 248inline std::ostream& operator<<(std::ostream &OS, const AliasSet &AS) { 249 AS.print(OS); 250 return OS; 251} 252 253 254class AliasSetTracker { 255 /// CallbackVH - A CallbackVH to arrange for AliasSetTracker to be 256 /// notified whenever a Value is deleted. 257 class ASTCallbackVH : public CallbackVH { 258 AliasSetTracker *AST; 259 virtual void deleted(); 260 public: 261 ASTCallbackVH(Value *V, AliasSetTracker *AST = 0); 262 }; 263 264 AliasAnalysis &AA; 265 ilist<AliasSet> AliasSets; 266 267 typedef DenseMap<ASTCallbackVH, AliasSet::PointerRec*, DenseMapInfo<Value*> > 268 PointerMapType; 269 270 // Map from pointers to their node 271 PointerMapType PointerMap; 272 273public: 274 /// AliasSetTracker ctor - Create an empty collection of AliasSets, and use 275 /// the specified alias analysis object to disambiguate load and store 276 /// addresses. 277 explicit AliasSetTracker(AliasAnalysis &aa) : AA(aa) {} 278 ~AliasSetTracker() { clear(); } 279 280 /// add methods - These methods are used to add different types of 281 /// instructions to the alias sets. Adding a new instruction can result in 282 /// one of three actions happening: 283 /// 284 /// 1. If the instruction doesn't alias any other sets, create a new set. 285 /// 2. If the instruction aliases exactly one set, add it to the set 286 /// 3. If the instruction aliases multiple sets, merge the sets, and add 287 /// the instruction to the result. 288 /// 289 /// These methods return true if inserting the instruction resulted in the 290 /// addition of a new alias set (i.e., the pointer did not alias anything). 291 /// 292 bool add(Value *Ptr, unsigned Size); // Add a location 293 bool add(LoadInst *LI); 294 bool add(StoreInst *SI); 295 bool add(FreeInst *FI); 296 bool add(VAArgInst *VAAI); 297 bool add(CallSite CS); // Call/Invoke instructions 298 bool add(CallInst *CI) { return add(CallSite(CI)); } 299 bool add(InvokeInst *II) { return add(CallSite(II)); } 300 bool add(Instruction *I); // Dispatch to one of the other add methods... 301 void add(BasicBlock &BB); // Add all instructions in basic block 302 void add(const AliasSetTracker &AST); // Add alias relations from another AST 303 304 /// remove methods - These methods are used to remove all entries that might 305 /// be aliased by the specified instruction. These methods return true if any 306 /// alias sets were eliminated. 307 bool remove(Value *Ptr, unsigned Size); // Remove a location 308 bool remove(LoadInst *LI); 309 bool remove(StoreInst *SI); 310 bool remove(FreeInst *FI); 311 bool remove(VAArgInst *VAAI); 312 bool remove(CallSite CS); 313 bool remove(CallInst *CI) { return remove(CallSite(CI)); } 314 bool remove(InvokeInst *II) { return remove(CallSite(II)); } 315 bool remove(Instruction *I); 316 void remove(AliasSet &AS); 317 318 void clear(); 319 320 /// getAliasSets - Return the alias sets that are active. 321 /// 322 const ilist<AliasSet> &getAliasSets() const { return AliasSets; } 323 324 /// getAliasSetForPointer - Return the alias set that the specified pointer 325 /// lives in. If the New argument is non-null, this method sets the value to 326 /// true if a new alias set is created to contain the pointer (because the 327 /// pointer didn't alias anything). 328 AliasSet &getAliasSetForPointer(Value *P, unsigned Size, bool *New = 0); 329 330 /// getAliasSetForPointerIfExists - Return the alias set containing the 331 /// location specified if one exists, otherwise return null. 332 AliasSet *getAliasSetForPointerIfExists(Value *P, unsigned Size) { 333 return findAliasSetForPointer(P, Size); 334 } 335 336 /// containsPointer - Return true if the specified location is represented by 337 /// this alias set, false otherwise. This does not modify the AST object or 338 /// alias sets. 339 bool containsPointer(Value *P, unsigned Size) const; 340 341 /// getAliasAnalysis - Return the underlying alias analysis object used by 342 /// this tracker. 343 AliasAnalysis &getAliasAnalysis() const { return AA; } 344 345 /// deleteValue method - This method is used to remove a pointer value from 346 /// the AliasSetTracker entirely. It should be used when an instruction is 347 /// deleted from the program to update the AST. If you don't use this, you 348 /// would have dangling pointers to deleted instructions. 349 /// 350 void deleteValue(Value *PtrVal); 351 352 /// copyValue - This method should be used whenever a preexisting value in the 353 /// program is copied or cloned, introducing a new value. Note that it is ok 354 /// for clients that use this method to introduce the same value multiple 355 /// times: if the tracker already knows about a value, it will ignore the 356 /// request. 357 /// 358 void copyValue(Value *From, Value *To); 359 360 361 typedef ilist<AliasSet>::iterator iterator; 362 typedef ilist<AliasSet>::const_iterator const_iterator; 363 364 const_iterator begin() const { return AliasSets.begin(); } 365 const_iterator end() const { return AliasSets.end(); } 366 367 iterator begin() { return AliasSets.begin(); } 368 iterator end() { return AliasSets.end(); } 369 370 void print(std::ostream &OS) const; 371 void print(std::ostream *OS) const { if (OS) print(*OS); } 372 void dump() const; 373 374private: 375 friend class AliasSet; 376 void removeAliasSet(AliasSet *AS); 377 378 // getEntryFor - Just like operator[] on the map, except that it creates an 379 // entry for the pointer if it doesn't already exist. 380 AliasSet::PointerRec &getEntryFor(Value *V) { 381 AliasSet::PointerRec *&Entry = PointerMap[ASTCallbackVH(V, this)]; 382 if (Entry == 0) 383 Entry = new AliasSet::PointerRec(V); 384 return *Entry; 385 } 386 387 AliasSet &addPointer(Value *P, unsigned Size, AliasSet::AccessType E, 388 bool &NewSet) { 389 NewSet = false; 390 AliasSet &AS = getAliasSetForPointer(P, Size, &NewSet); 391 AS.AccessTy |= E; 392 return AS; 393 } 394 AliasSet *findAliasSetForPointer(const Value *Ptr, unsigned Size); 395 396 AliasSet *findAliasSetForCallSite(CallSite CS); 397}; 398 399inline std::ostream& operator<<(std::ostream &OS, const AliasSetTracker &AST) { 400 AST.print(OS); 401 return OS; 402} 403 404} // End llvm namespace 405 406#endif 407