AliasAnalysis.h revision cc10244d7725f191bdc91cd62befff0c97257c7b
1b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato//===- llvm/Analysis/AliasAnalysis.h - Alias Analysis Interface -*- C++ -*-===// 2b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// 3b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// The LLVM Compiler Infrastructure 4b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// 5b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// This file is distributed under the University of Illinois Open Source 6b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// License. See LICENSE.TXT for details. 7b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// 8b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato//===----------------------------------------------------------------------===// 9b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// 10b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// This file defines the generic AliasAnalysis interface, which is used as the 11b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// common interface used by all clients of alias analysis information, and 12b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// implemented by all alias analysis implementations. Mod/Ref information is 13b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// also captured by this interface. 14b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// 15b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// Implementations of this interface must implement the various virtual methods, 16b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// which automatically provides functionality for the entire suite of client 17b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// APIs. 18b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// 19b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// This API identifies memory regions with the Location class. The pointer 20b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// component specifies the base memory address of the region. The Size specifies 21b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// the maximum size (in address units) of the memory region, or UnknownSize if 22b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// the size is not known. The TBAA tag identifies the "type" of the memory 23b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// reference; see the TypeBasedAliasAnalysis class for details. 24b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// 25b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// Some non-obvious details include: 26b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// - Pointers that point to two completely different objects in memory never 27b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// alias, regardless of the value of the Size component. 28b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// - NoAlias doesn't imply inequal pointers. The most obvious example of this 29b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// is two pointers to constant memory. Even if they are equal, constant 30b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// memory is never stored to, so there will never be any dependencies. 31b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// In this and other situations, the pointers may be both NoAlias and 32b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// MustAlias at the same time. The current API can only return one result, 33b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// though this is rarely a problem in practice. 34b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato// 35b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato//===----------------------------------------------------------------------===// 36b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 37b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato#ifndef LLVM_ANALYSIS_ALIAS_ANALYSIS_H 38b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato#define LLVM_ANALYSIS_ALIAS_ANALYSIS_H 39b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 40b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato#include "llvm/Support/CallSite.h" 41b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato#include <vector> 42b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 43b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratonamespace llvm { 44b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 45b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoclass LoadInst; 46b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoclass StoreInst; 47b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoclass VAArgInst; 48b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoclass TargetData; 49b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoclass Pass; 50b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoclass AnalysisUsage; 51b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoclass MemTransferInst; 52b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoclass MemIntrinsic; 53b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 54b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoclass AliasAnalysis { 55b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoprotected: 56b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato const TargetData *TD; 57b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 58b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoprivate: 59b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato AliasAnalysis *AA; // Previous Alias Analysis to chain to. 60b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 61b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onoratoprotected: 62b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /// InitializeAliasAnalysis - Subclasses must call this method to initialize 63b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /// the AliasAnalysis interface before any other methods are called. This is 64b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /// typically called by the run* methods of these subclasses. This may be 65b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /// called multiple times. 66b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /// 67b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato void InitializeAliasAnalysis(Pass *P); 68b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 69b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /// getAnalysisUsage - All alias analysis implementations should invoke this 70b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato /// directly (using AliasAnalysis::getAnalysisUsage(AU)). 71b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato virtual void getAnalysisUsage(AnalysisUsage &AU) const; 72b72c5c2e5482cf10117b2b25f642f7616b2326c3Joe Onorato 73public: 74 static char ID; // Class identification, replacement for typeinfo 75 AliasAnalysis() : TD(0), AA(0) {} 76 virtual ~AliasAnalysis(); // We want to be subclassed 77 78 /// UnknownSize - This is a special value which can be used with the 79 /// size arguments in alias queries to indicate that the caller does not 80 /// know the sizes of the potential memory references. 81 static uint64_t const UnknownSize = ~UINT64_C(0); 82 83 /// getTargetData - Return a pointer to the current TargetData object, or 84 /// null if no TargetData object is available. 85 /// 86 const TargetData *getTargetData() const { return TD; } 87 88 /// getTypeStoreSize - Return the TargetData store size for the given type, 89 /// if known, or a conservative value otherwise. 90 /// 91 uint64_t getTypeStoreSize(const Type *Ty); 92 93 //===--------------------------------------------------------------------===// 94 /// Alias Queries... 95 /// 96 97 /// Location - A description of a memory location. 98 struct Location { 99 /// Ptr - The address of the start of the location. 100 const Value *Ptr; 101 /// Size - The maximum size of the location, in address-units, or 102 /// UnknownSize if the size is not known. Note that an unknown size does 103 /// not mean the pointer aliases the entire virtual address space, because 104 /// there are restrictions on stepping out of one object and into another. 105 /// See http://llvm.org/docs/LangRef.html#pointeraliasing 106 uint64_t Size; 107 /// TBAATag - The metadata node which describes the TBAA type of 108 /// the location, or null if there is no known unique tag. 109 const MDNode *TBAATag; 110 111 explicit Location(const Value *P = 0, uint64_t S = UnknownSize, 112 const MDNode *N = 0) 113 : Ptr(P), Size(S), TBAATag(N) {} 114 115 Location getWithNewPtr(const Value *NewPtr) const { 116 Location Copy(*this); 117 Copy.Ptr = NewPtr; 118 return Copy; 119 } 120 121 Location getWithNewSize(uint64_t NewSize) const { 122 Location Copy(*this); 123 Copy.Size = NewSize; 124 return Copy; 125 } 126 127 Location getWithoutTBAATag() const { 128 Location Copy(*this); 129 Copy.TBAATag = 0; 130 return Copy; 131 } 132 }; 133 134 /// getLocation - Fill in Loc with information about the memory reference by 135 /// the given instruction. 136 Location getLocation(const LoadInst *LI); 137 Location getLocation(const StoreInst *SI); 138 Location getLocation(const VAArgInst *VI); 139 static Location getLocationForSource(const MemTransferInst *MTI); 140 static Location getLocationForDest(const MemIntrinsic *MI); 141 142 /// Alias analysis result - Either we know for sure that it does not alias, we 143 /// know for sure it must alias, or we don't know anything: The two pointers 144 /// _might_ alias. This enum is designed so you can do things like: 145 /// if (AA.alias(P1, P2)) { ... } 146 /// to check to see if two pointers might alias. 147 /// 148 /// See docs/AliasAnalysis.html for more information on the specific meanings 149 /// of these values. 150 /// 151 enum AliasResult { 152 NoAlias = 0, ///< No dependencies. 153 MayAlias = 1, ///< Anything goes. 154 MustAlias = 2 ///< Pointers are equal. 155 }; 156 157 /// alias - The main low level interface to the alias analysis implementation. 158 /// Returns an AliasResult indicating whether the two pointers are aliased to 159 /// each other. This is the interface that must be implemented by specific 160 /// alias analysis implementations. 161 virtual AliasResult alias(const Location &LocA, const Location &LocB); 162 163 /// alias - A convenience wrapper. 164 AliasResult alias(const Value *V1, uint64_t V1Size, 165 const Value *V2, uint64_t V2Size) { 166 return alias(Location(V1, V1Size), Location(V2, V2Size)); 167 } 168 169 /// alias - A convenience wrapper. 170 AliasResult alias(const Value *V1, const Value *V2) { 171 return alias(V1, UnknownSize, V2, UnknownSize); 172 } 173 174 /// isNoAlias - A trivial helper function to check to see if the specified 175 /// pointers are no-alias. 176 bool isNoAlias(const Location &LocA, const Location &LocB) { 177 return alias(LocA, LocB) == NoAlias; 178 } 179 180 /// isNoAlias - A convenience wrapper. 181 bool isNoAlias(const Value *V1, uint64_t V1Size, 182 const Value *V2, uint64_t V2Size) { 183 return isNoAlias(Location(V1, V1Size), Location(V2, V2Size)); 184 } 185 186 /// isMustAlias - A convenience wrapper. 187 bool isMustAlias(const Location &LocA, const Location &LocB) { 188 return alias(LocA, LocB) == MustAlias; 189 } 190 191 /// isMustAlias - A convenience wrapper. 192 bool isMustAlias(const Value *V1, const Value *V2) { 193 return alias(V1, 1, V2, 1) == MustAlias; 194 } 195 196 /// pointsToConstantMemory - If the specified memory location is 197 /// known to be constant, return true. If OrLocal is true and the 198 /// specified memory location is known to be "local" (derived from 199 /// an alloca), return true. Otherwise return false. 200 virtual bool pointsToConstantMemory(const Location &Loc, 201 bool OrLocal = false); 202 203 /// pointsToConstantMemory - A convenient wrapper. 204 bool pointsToConstantMemory(const Value *P, bool OrLocal = false) { 205 return pointsToConstantMemory(Location(P), OrLocal); 206 } 207 208 //===--------------------------------------------------------------------===// 209 /// Simple mod/ref information... 210 /// 211 212 /// ModRefResult - Represent the result of a mod/ref query. Mod and Ref are 213 /// bits which may be or'd together. 214 /// 215 enum ModRefResult { NoModRef = 0, Ref = 1, Mod = 2, ModRef = 3 }; 216 217 /// These values define additional bits used to define the 218 /// ModRefBehavior values. 219 enum { Nowhere = 0, ArgumentPointees = 4, Anywhere = 8 | ArgumentPointees }; 220 221 /// ModRefBehavior - Summary of how a function affects memory in the program. 222 /// Loads from constant globals are not considered memory accesses for this 223 /// interface. Also, functions may freely modify stack space local to their 224 /// invocation without having to report it through these interfaces. 225 enum ModRefBehavior { 226 /// DoesNotAccessMemory - This function does not perform any non-local loads 227 /// or stores to memory. 228 /// 229 /// This property corresponds to the GCC 'const' attribute. 230 /// This property corresponds to the LLVM IR 'readnone' attribute. 231 /// This property corresponds to the IntrNoMem LLVM intrinsic flag. 232 DoesNotAccessMemory = Nowhere | NoModRef, 233 234 /// OnlyReadsArgumentPointees - The only memory references in this function 235 /// (if it has any) are non-volatile loads from objects pointed to by its 236 /// pointer-typed arguments, with arbitrary offsets. 237 /// 238 /// This property corresponds to the IntrReadArgMem LLVM intrinsic flag. 239 OnlyReadsArgumentPointees = ArgumentPointees | Ref, 240 241 /// OnlyAccessesArgumentPointees - The only memory references in this 242 /// function (if it has any) are non-volatile loads and stores from objects 243 /// pointed to by its pointer-typed arguments, with arbitrary offsets. 244 /// 245 /// This property corresponds to the IntrReadWriteArgMem LLVM intrinsic flag. 246 OnlyAccessesArgumentPointees = ArgumentPointees | ModRef, 247 248 /// OnlyReadsMemory - This function does not perform any non-local stores or 249 /// volatile loads, but may read from any memory location. 250 /// 251 /// This property corresponds to the GCC 'pure' attribute. 252 /// This property corresponds to the LLVM IR 'readonly' attribute. 253 /// This property corresponds to the IntrReadMem LLVM intrinsic flag. 254 OnlyReadsMemory = Anywhere | Ref, 255 256 /// UnknownModRefBehavior - This indicates that the function could not be 257 /// classified into one of the behaviors above. 258 UnknownModRefBehavior = Anywhere | ModRef 259 }; 260 261 /// getModRefBehavior - Return the behavior when calling the given call site. 262 virtual ModRefBehavior getModRefBehavior(ImmutableCallSite CS); 263 264 /// getModRefBehavior - Return the behavior when calling the given function. 265 /// For use when the call site is not known. 266 virtual ModRefBehavior getModRefBehavior(const Function *F); 267 268 /// doesNotAccessMemory - If the specified call is known to never read or 269 /// write memory, return true. If the call only reads from known-constant 270 /// memory, it is also legal to return true. Calls that unwind the stack 271 /// are legal for this predicate. 272 /// 273 /// Many optimizations (such as CSE and LICM) can be performed on such calls 274 /// without worrying about aliasing properties, and many calls have this 275 /// property (e.g. calls to 'sin' and 'cos'). 276 /// 277 /// This property corresponds to the GCC 'const' attribute. 278 /// 279 bool doesNotAccessMemory(ImmutableCallSite CS) { 280 return getModRefBehavior(CS) == DoesNotAccessMemory; 281 } 282 283 /// doesNotAccessMemory - If the specified function is known to never read or 284 /// write memory, return true. For use when the call site is not known. 285 /// 286 bool doesNotAccessMemory(const Function *F) { 287 return getModRefBehavior(F) == DoesNotAccessMemory; 288 } 289 290 /// onlyReadsMemory - If the specified call is known to only read from 291 /// non-volatile memory (or not access memory at all), return true. Calls 292 /// that unwind the stack are legal for this predicate. 293 /// 294 /// This property allows many common optimizations to be performed in the 295 /// absence of interfering store instructions, such as CSE of strlen calls. 296 /// 297 /// This property corresponds to the GCC 'pure' attribute. 298 /// 299 bool onlyReadsMemory(ImmutableCallSite CS) { 300 return onlyReadsMemory(getModRefBehavior(CS)); 301 } 302 303 /// onlyReadsMemory - If the specified function is known to only read from 304 /// non-volatile memory (or not access memory at all), return true. For use 305 /// when the call site is not known. 306 /// 307 bool onlyReadsMemory(const Function *F) { 308 return onlyReadsMemory(getModRefBehavior(F)); 309 } 310 311 /// onlyReadsMemory - Return true if functions with the specified behavior are 312 /// known to only read from non-volatile memory (or not access memory at all). 313 /// 314 static bool onlyReadsMemory(ModRefBehavior MRB) { 315 return !(MRB & Mod); 316 } 317 318 /// onlyAccessesArgPointees - Return true if functions with the specified 319 /// behavior are known to read and write at most from objects pointed to by 320 /// their pointer-typed arguments (with arbitrary offsets). 321 /// 322 static bool onlyAccessesArgPointees(ModRefBehavior MRB) { 323 return !(MRB & Anywhere & ~ArgumentPointees); 324 } 325 326 /// doesAccessArgPointees - Return true if functions with the specified 327 /// behavior are known to potentially read or write from objects pointed 328 /// to be their pointer-typed arguments (with arbitrary offsets). 329 /// 330 static bool doesAccessArgPointees(ModRefBehavior MRB) { 331 return (MRB & ModRef) && (MRB & ArgumentPointees); 332 } 333 334 /// getModRefInfo - Return information about whether or not an instruction may 335 /// read or write the specified memory location. An instruction 336 /// that doesn't read or write memory may be trivially LICM'd for example. 337 ModRefResult getModRefInfo(const Instruction *I, 338 const Location &Loc) { 339 switch (I->getOpcode()) { 340 case Instruction::VAArg: return getModRefInfo((const VAArgInst*)I, Loc); 341 case Instruction::Load: return getModRefInfo((const LoadInst*)I, Loc); 342 case Instruction::Store: return getModRefInfo((const StoreInst*)I, Loc); 343 case Instruction::Call: return getModRefInfo((const CallInst*)I, Loc); 344 case Instruction::Invoke: return getModRefInfo((const InvokeInst*)I,Loc); 345 default: return NoModRef; 346 } 347 } 348 349 /// getModRefInfo - A convenience wrapper. 350 ModRefResult getModRefInfo(const Instruction *I, 351 const Value *P, uint64_t Size) { 352 return getModRefInfo(I, Location(P, Size)); 353 } 354 355 /// getModRefInfo (for call sites) - Return whether information about whether 356 /// a particular call site modifies or reads the specified memory location. 357 virtual ModRefResult getModRefInfo(ImmutableCallSite CS, 358 const Location &Loc); 359 360 /// getModRefInfo (for call sites) - A convenience wrapper. 361 ModRefResult getModRefInfo(ImmutableCallSite CS, 362 const Value *P, uint64_t Size) { 363 return getModRefInfo(CS, Location(P, Size)); 364 } 365 366 /// getModRefInfo (for calls) - Return whether information about whether 367 /// a particular call modifies or reads the specified memory location. 368 ModRefResult getModRefInfo(const CallInst *C, const Location &Loc) { 369 return getModRefInfo(ImmutableCallSite(C), Loc); 370 } 371 372 /// getModRefInfo (for calls) - A convenience wrapper. 373 ModRefResult getModRefInfo(const CallInst *C, const Value *P, uint64_t Size) { 374 return getModRefInfo(C, Location(P, Size)); 375 } 376 377 /// getModRefInfo (for invokes) - Return whether information about whether 378 /// a particular invoke modifies or reads the specified memory location. 379 ModRefResult getModRefInfo(const InvokeInst *I, 380 const Location &Loc) { 381 return getModRefInfo(ImmutableCallSite(I), Loc); 382 } 383 384 /// getModRefInfo (for invokes) - A convenience wrapper. 385 ModRefResult getModRefInfo(const InvokeInst *I, 386 const Value *P, uint64_t Size) { 387 return getModRefInfo(I, Location(P, Size)); 388 } 389 390 /// getModRefInfo (for loads) - Return whether information about whether 391 /// a particular load modifies or reads the specified memory location. 392 ModRefResult getModRefInfo(const LoadInst *L, const Location &Loc); 393 394 /// getModRefInfo (for loads) - A convenience wrapper. 395 ModRefResult getModRefInfo(const LoadInst *L, const Value *P, uint64_t Size) { 396 return getModRefInfo(L, Location(P, Size)); 397 } 398 399 /// getModRefInfo (for stores) - Return whether information about whether 400 /// a particular store modifies or reads the specified memory location. 401 ModRefResult getModRefInfo(const StoreInst *S, const Location &Loc); 402 403 /// getModRefInfo (for stores) - A convenience wrapper. 404 ModRefResult getModRefInfo(const StoreInst *S, const Value *P, uint64_t Size) { 405 return getModRefInfo(S, Location(P, Size)); 406 } 407 408 /// getModRefInfo (for va_args) - Return whether information about whether 409 /// a particular va_arg modifies or reads the specified memory location. 410 ModRefResult getModRefInfo(const VAArgInst* I, const Location &Loc); 411 412 /// getModRefInfo (for va_args) - A convenience wrapper. 413 ModRefResult getModRefInfo(const VAArgInst* I, const Value* P, uint64_t Size) { 414 return getModRefInfo(I, Location(P, Size)); 415 } 416 417 /// getModRefInfo - Return information about whether two call sites may refer 418 /// to the same set of memory locations. See 419 /// http://llvm.org/docs/AliasAnalysis.html#ModRefInfo 420 /// for details. 421 virtual ModRefResult getModRefInfo(ImmutableCallSite CS1, 422 ImmutableCallSite CS2); 423 424 //===--------------------------------------------------------------------===// 425 /// Higher level methods for querying mod/ref information. 426 /// 427 428 /// canBasicBlockModify - Return true if it is possible for execution of the 429 /// specified basic block to modify the value pointed to by Ptr. 430 bool canBasicBlockModify(const BasicBlock &BB, const Location &Loc); 431 432 /// canBasicBlockModify - A convenience wrapper. 433 bool canBasicBlockModify(const BasicBlock &BB, const Value *P, uint64_t Size){ 434 return canBasicBlockModify(BB, Location(P, Size)); 435 } 436 437 /// canInstructionRangeModify - Return true if it is possible for the 438 /// execution of the specified instructions to modify the value pointed to by 439 /// Ptr. The instructions to consider are all of the instructions in the 440 /// range of [I1,I2] INCLUSIVE. I1 and I2 must be in the same basic block. 441 bool canInstructionRangeModify(const Instruction &I1, const Instruction &I2, 442 const Location &Loc); 443 444 /// canInstructionRangeModify - A convenience wrapper. 445 bool canInstructionRangeModify(const Instruction &I1, const Instruction &I2, 446 const Value *Ptr, uint64_t Size) { 447 return canInstructionRangeModify(I1, I2, Location(Ptr, Size)); 448 } 449 450 //===--------------------------------------------------------------------===// 451 /// Methods that clients should call when they transform the program to allow 452 /// alias analyses to update their internal data structures. Note that these 453 /// methods may be called on any instruction, regardless of whether or not 454 /// they have pointer-analysis implications. 455 /// 456 457 /// deleteValue - This method should be called whenever an LLVM Value is 458 /// deleted from the program, for example when an instruction is found to be 459 /// redundant and is eliminated. 460 /// 461 virtual void deleteValue(Value *V); 462 463 /// copyValue - This method should be used whenever a preexisting value in the 464 /// program is copied or cloned, introducing a new value. Note that analysis 465 /// implementations should tolerate clients that use this method to introduce 466 /// the same value multiple times: if the analysis already knows about a 467 /// value, it should ignore the request. 468 /// 469 virtual void copyValue(Value *From, Value *To); 470 471 /// replaceWithNewValue - This method is the obvious combination of the two 472 /// above, and it provided as a helper to simplify client code. 473 /// 474 void replaceWithNewValue(Value *Old, Value *New) { 475 copyValue(Old, New); 476 deleteValue(Old); 477 } 478}; 479 480/// isNoAliasCall - Return true if this pointer is returned by a noalias 481/// function. 482bool isNoAliasCall(const Value *V); 483 484/// isIdentifiedObject - Return true if this pointer refers to a distinct and 485/// identifiable object. This returns true for: 486/// Global Variables and Functions (but not Global Aliases) 487/// Allocas and Mallocs 488/// ByVal and NoAlias Arguments 489/// NoAlias returns 490/// 491bool isIdentifiedObject(const Value *V); 492 493} // End llvm namespace 494 495#endif 496