AliasSetTracker.h revision 791102fb1192ac9483274e54cbc42480c9b1af10
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(raw_ostream &OS) const; 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 raw_ostream& operator<<(raw_ostream &OS, const AliasSet &AS) { 248 AS.print(OS); 249 return OS; 250} 251 252 253class AliasSetTracker { 254 /// CallbackVH - A CallbackVH to arrange for AliasSetTracker to be 255 /// notified whenever a Value is deleted. 256 class ASTCallbackVH : public CallbackVH { 257 AliasSetTracker *AST; 258 virtual void deleted(); 259 public: 260 ASTCallbackVH(Value *V, AliasSetTracker *AST = 0); 261 ASTCallbackVH &operator=(Value *V); 262 }; 263 /// ASTCallbackVHDenseMapInfo - Traits to tell DenseMap that ASTCallbackVH 264 /// is not a POD (it needs its destructor called). 265 struct ASTCallbackVHDenseMapInfo : public DenseMapInfo<Value *> { 266 static bool isPod() { return false; } 267 }; 268 269 AliasAnalysis &AA; 270 ilist<AliasSet> AliasSets; 271 272 typedef DenseMap<ASTCallbackVH, AliasSet::PointerRec*, 273 ASTCallbackVHDenseMapInfo> 274 PointerMapType; 275 276 // Map from pointers to their node 277 PointerMapType PointerMap; 278 279public: 280 /// AliasSetTracker ctor - Create an empty collection of AliasSets, and use 281 /// the specified alias analysis object to disambiguate load and store 282 /// addresses. 283 explicit AliasSetTracker(AliasAnalysis &aa) : AA(aa) {} 284 ~AliasSetTracker() { clear(); } 285 286 /// add methods - These methods are used to add different types of 287 /// instructions to the alias sets. Adding a new instruction can result in 288 /// one of three actions happening: 289 /// 290 /// 1. If the instruction doesn't alias any other sets, create a new set. 291 /// 2. If the instruction aliases exactly one set, add it to the set 292 /// 3. If the instruction aliases multiple sets, merge the sets, and add 293 /// the instruction to the result. 294 /// 295 /// These methods return true if inserting the instruction resulted in the 296 /// addition of a new alias set (i.e., the pointer did not alias anything). 297 /// 298 bool add(Value *Ptr, unsigned Size); // Add a location 299 bool add(LoadInst *LI); 300 bool add(StoreInst *SI); 301 bool add(FreeInst *FI); 302 bool add(VAArgInst *VAAI); 303 bool add(CallSite CS); // Call/Invoke instructions 304 bool add(CallInst *CI) { return add(CallSite(CI)); } 305 bool add(InvokeInst *II) { return add(CallSite(II)); } 306 bool add(Instruction *I); // Dispatch to one of the other add methods... 307 void add(BasicBlock &BB); // Add all instructions in basic block 308 void add(const AliasSetTracker &AST); // Add alias relations from another AST 309 310 /// remove methods - These methods are used to remove all entries that might 311 /// be aliased by the specified instruction. These methods return true if any 312 /// alias sets were eliminated. 313 bool remove(Value *Ptr, unsigned Size); // Remove a location 314 bool remove(LoadInst *LI); 315 bool remove(StoreInst *SI); 316 bool remove(FreeInst *FI); 317 bool remove(VAArgInst *VAAI); 318 bool remove(CallSite CS); 319 bool remove(CallInst *CI) { return remove(CallSite(CI)); } 320 bool remove(InvokeInst *II) { return remove(CallSite(II)); } 321 bool remove(Instruction *I); 322 void remove(AliasSet &AS); 323 324 void clear(); 325 326 /// getAliasSets - Return the alias sets that are active. 327 /// 328 const ilist<AliasSet> &getAliasSets() const { return AliasSets; } 329 330 /// getAliasSetForPointer - Return the alias set that the specified pointer 331 /// lives in. If the New argument is non-null, this method sets the value to 332 /// true if a new alias set is created to contain the pointer (because the 333 /// pointer didn't alias anything). 334 AliasSet &getAliasSetForPointer(Value *P, unsigned Size, bool *New = 0); 335 336 /// getAliasSetForPointerIfExists - Return the alias set containing the 337 /// location specified if one exists, otherwise return null. 338 AliasSet *getAliasSetForPointerIfExists(Value *P, unsigned Size) { 339 return findAliasSetForPointer(P, Size); 340 } 341 342 /// containsPointer - Return true if the specified location is represented by 343 /// this alias set, false otherwise. This does not modify the AST object or 344 /// alias sets. 345 bool containsPointer(Value *P, unsigned Size) const; 346 347 /// getAliasAnalysis - Return the underlying alias analysis object used by 348 /// this tracker. 349 AliasAnalysis &getAliasAnalysis() const { return AA; } 350 351 /// deleteValue method - This method is used to remove a pointer value from 352 /// the AliasSetTracker entirely. It should be used when an instruction is 353 /// deleted from the program to update the AST. If you don't use this, you 354 /// would have dangling pointers to deleted instructions. 355 /// 356 void deleteValue(Value *PtrVal); 357 358 /// copyValue - This method should be used whenever a preexisting value in the 359 /// program is copied or cloned, introducing a new value. Note that it is ok 360 /// for clients that use this method to introduce the same value multiple 361 /// times: if the tracker already knows about a value, it will ignore the 362 /// request. 363 /// 364 void copyValue(Value *From, Value *To); 365 366 367 typedef ilist<AliasSet>::iterator iterator; 368 typedef ilist<AliasSet>::const_iterator const_iterator; 369 370 const_iterator begin() const { return AliasSets.begin(); } 371 const_iterator end() const { return AliasSets.end(); } 372 373 iterator begin() { return AliasSets.begin(); } 374 iterator end() { return AliasSets.end(); } 375 376 void print(raw_ostream &OS) const; 377 void dump() const; 378 379private: 380 friend class AliasSet; 381 void removeAliasSet(AliasSet *AS); 382 383 // getEntryFor - Just like operator[] on the map, except that it creates an 384 // entry for the pointer if it doesn't already exist. 385 AliasSet::PointerRec &getEntryFor(Value *V) { 386 AliasSet::PointerRec *&Entry = PointerMap[ASTCallbackVH(V, this)]; 387 if (Entry == 0) 388 Entry = new AliasSet::PointerRec(V); 389 return *Entry; 390 } 391 392 AliasSet &addPointer(Value *P, unsigned Size, AliasSet::AccessType E, 393 bool &NewSet) { 394 NewSet = false; 395 AliasSet &AS = getAliasSetForPointer(P, Size, &NewSet); 396 AS.AccessTy |= E; 397 return AS; 398 } 399 AliasSet *findAliasSetForPointer(const Value *Ptr, unsigned Size); 400 401 AliasSet *findAliasSetForCallSite(CallSite CS); 402}; 403 404inline raw_ostream& operator<<(raw_ostream &OS, const AliasSetTracker &AST) { 405 AST.print(OS); 406 return OS; 407} 408 409} // End llvm namespace 410 411#endif 412