MemoryBuiltins.cpp revision eb7c6865cd8d44a882aa7c3e10e1d976f333344f
1//===------ MemoryBuiltins.cpp - Identify calls to memory builtins --------===// 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 family of functions identifies calls to builtin functions that allocate 11// or free memory. 12// 13//===----------------------------------------------------------------------===// 14 15#define DEBUG_TYPE "memory-builtins" 16#include "llvm/ADT/Statistic.h" 17#include "llvm/ADT/STLExtras.h" 18#include "llvm/Analysis/MemoryBuiltins.h" 19#include "llvm/GlobalVariable.h" 20#include "llvm/Instructions.h" 21#include "llvm/Intrinsics.h" 22#include "llvm/Metadata.h" 23#include "llvm/Module.h" 24#include "llvm/Analysis/ValueTracking.h" 25#include "llvm/Support/Debug.h" 26#include "llvm/Support/MathExtras.h" 27#include "llvm/Support/raw_ostream.h" 28#include "llvm/Target/TargetData.h" 29#include "llvm/Transforms/Utils/Local.h" 30using namespace llvm; 31 32enum AllocType { 33 MallocLike = 1<<0, // allocates 34 CallocLike = 1<<1, // allocates + bzero 35 ReallocLike = 1<<2, // reallocates 36 StrDupLike = 1<<3, 37 AllocLike = MallocLike | CallocLike | StrDupLike, 38 AnyAlloc = MallocLike | CallocLike | ReallocLike | StrDupLike 39}; 40 41struct AllocFnsTy { 42 const char *Name; 43 AllocType AllocTy; 44 unsigned char NumParams; 45 // First and Second size parameters (or -1 if unused) 46 signed char FstParam, SndParam; 47}; 48 49static const AllocFnsTy AllocationFnData[] = { 50 {"malloc", MallocLike, 1, 0, -1}, 51 {"valloc", MallocLike, 1, 0, -1}, 52 {"_Znwj", MallocLike, 1, 0, -1}, // operator new(unsigned int) 53 {"_Znwm", MallocLike, 1, 0, -1}, // operator new(unsigned long) 54 {"_Znaj", MallocLike, 1, 0, -1}, // operator new[](unsigned int) 55 {"_Znam", MallocLike, 1, 0, -1}, // operator new[](unsigned long) 56 {"posix_memalign", MallocLike, 3, 2, -1}, 57 {"calloc", CallocLike, 2, 0, 1}, 58 {"realloc", ReallocLike, 2, 1, -1}, 59 {"reallocf", ReallocLike, 2, 1, -1}, 60 {"strdup", StrDupLike, 1, -1, -1}, 61 {"strndup", StrDupLike, 2, -1, -1} 62}; 63 64 65static Function *getCalledFunction(const Value *V, bool LookThroughBitCast) { 66 if (LookThroughBitCast) 67 V = V->stripPointerCasts(); 68 69 Value *I = const_cast<Value*>(V); 70 CallSite CS; 71 if (CallInst *CI = dyn_cast<CallInst>(I)) 72 CS = CallSite(CI); 73 else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) 74 CS = CallSite(II); 75 else 76 return 0; 77 78 Function *Callee = CS.getCalledFunction(); 79 if (!Callee || !Callee->isDeclaration()) 80 return 0; 81 return Callee; 82} 83 84/// \brief Returns the allocation data for the given value if it is a call to a 85/// known allocation function, and NULL otherwise. 86static const AllocFnsTy *getAllocationData(const Value *V, AllocType AllocTy, 87 bool LookThroughBitCast = false) { 88 Function *Callee = getCalledFunction(V, LookThroughBitCast); 89 if (!Callee) 90 return 0; 91 92 unsigned i = 0; 93 bool found = false; 94 for ( ; i < array_lengthof(AllocationFnData); ++i) { 95 if (Callee->getName() == AllocationFnData[i].Name) { 96 found = true; 97 break; 98 } 99 } 100 if (!found) 101 return 0; 102 103 const AllocFnsTy *FnData = &AllocationFnData[i]; 104 if ((FnData->AllocTy & AllocTy) == 0) 105 return 0; 106 107 // Check function prototype. 108 // FIXME: Check the nobuiltin metadata?? (PR5130) 109 int FstParam = FnData->FstParam; 110 int SndParam = FnData->SndParam; 111 FunctionType *FTy = Callee->getFunctionType(); 112 113 if (FTy->getReturnType() == Type::getInt8PtrTy(FTy->getContext()) && 114 FTy->getNumParams() == FnData->NumParams && 115 (FstParam < 0 || 116 (FTy->getParamType(FstParam)->isIntegerTy(32) || 117 FTy->getParamType(FstParam)->isIntegerTy(64))) && 118 (SndParam < 0 || 119 FTy->getParamType(SndParam)->isIntegerTy(32) || 120 FTy->getParamType(SndParam)->isIntegerTy(64))) 121 return FnData; 122 return 0; 123} 124 125static bool hasNoAliasAttr(const Value *V, bool LookThroughBitCast) { 126 Function *Callee = getCalledFunction(V, LookThroughBitCast); 127 return Callee && Callee->hasFnAttr(Attribute::NoAlias); 128} 129 130 131/// \brief Tests if a value is a call or invoke to a library function that 132/// allocates or reallocates memory (either malloc, calloc, realloc, or strdup 133/// like). 134bool llvm::isAllocationFn(const Value *V, bool LookThroughBitCast) { 135 return getAllocationData(V, AnyAlloc, LookThroughBitCast); 136} 137 138/// \brief Tests if a value is a call or invoke to a function that returns a 139/// NoAlias pointer (including malloc/calloc/strdup-like functions). 140bool llvm::isNoAliasFn(const Value *V, bool LookThroughBitCast) { 141 return isAllocLikeFn(V, LookThroughBitCast) || 142 hasNoAliasAttr(V, LookThroughBitCast); 143} 144 145/// \brief Tests if a value is a call or invoke to a library function that 146/// allocates uninitialized memory (such as malloc). 147bool llvm::isMallocLikeFn(const Value *V, bool LookThroughBitCast) { 148 return getAllocationData(V, MallocLike, LookThroughBitCast); 149} 150 151/// \brief Tests if a value is a call or invoke to a library function that 152/// allocates zero-filled memory (such as calloc). 153bool llvm::isCallocLikeFn(const Value *V, bool LookThroughBitCast) { 154 return getAllocationData(V, CallocLike, LookThroughBitCast); 155} 156 157/// \brief Tests if a value is a call or invoke to a library function that 158/// allocates memory (either malloc, calloc, or strdup like). 159bool llvm::isAllocLikeFn(const Value *V, bool LookThroughBitCast) { 160 return getAllocationData(V, AllocLike, LookThroughBitCast); 161} 162 163/// \brief Tests if a value is a call or invoke to a library function that 164/// reallocates memory (such as realloc). 165bool llvm::isReallocLikeFn(const Value *V, bool LookThroughBitCast) { 166 return getAllocationData(V, ReallocLike, LookThroughBitCast); 167} 168 169/// extractMallocCall - Returns the corresponding CallInst if the instruction 170/// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we 171/// ignore InvokeInst here. 172const CallInst *llvm::extractMallocCall(const Value *I) { 173 return isMallocLikeFn(I) ? dyn_cast<CallInst>(I) : 0; 174} 175 176static Value *computeArraySize(const CallInst *CI, const TargetData *TD, 177 bool LookThroughSExt = false) { 178 if (!CI) 179 return NULL; 180 181 // The size of the malloc's result type must be known to determine array size. 182 Type *T = getMallocAllocatedType(CI); 183 if (!T || !T->isSized() || !TD) 184 return NULL; 185 186 unsigned ElementSize = TD->getTypeAllocSize(T); 187 if (StructType *ST = dyn_cast<StructType>(T)) 188 ElementSize = TD->getStructLayout(ST)->getSizeInBytes(); 189 190 // If malloc call's arg can be determined to be a multiple of ElementSize, 191 // return the multiple. Otherwise, return NULL. 192 Value *MallocArg = CI->getArgOperand(0); 193 Value *Multiple = NULL; 194 if (ComputeMultiple(MallocArg, ElementSize, Multiple, 195 LookThroughSExt)) 196 return Multiple; 197 198 return NULL; 199} 200 201/// isArrayMalloc - Returns the corresponding CallInst if the instruction 202/// is a call to malloc whose array size can be determined and the array size 203/// is not constant 1. Otherwise, return NULL. 204const CallInst *llvm::isArrayMalloc(const Value *I, const TargetData *TD) { 205 const CallInst *CI = extractMallocCall(I); 206 Value *ArraySize = computeArraySize(CI, TD); 207 208 if (ArraySize && 209 ArraySize != ConstantInt::get(CI->getArgOperand(0)->getType(), 1)) 210 return CI; 211 212 // CI is a non-array malloc or we can't figure out that it is an array malloc. 213 return NULL; 214} 215 216/// getMallocType - Returns the PointerType resulting from the malloc call. 217/// The PointerType depends on the number of bitcast uses of the malloc call: 218/// 0: PointerType is the calls' return type. 219/// 1: PointerType is the bitcast's result type. 220/// >1: Unique PointerType cannot be determined, return NULL. 221PointerType *llvm::getMallocType(const CallInst *CI) { 222 assert(isMallocLikeFn(CI) && "getMallocType and not malloc call"); 223 224 PointerType *MallocType = NULL; 225 unsigned NumOfBitCastUses = 0; 226 227 // Determine if CallInst has a bitcast use. 228 for (Value::const_use_iterator UI = CI->use_begin(), E = CI->use_end(); 229 UI != E; ) 230 if (const BitCastInst *BCI = dyn_cast<BitCastInst>(*UI++)) { 231 MallocType = cast<PointerType>(BCI->getDestTy()); 232 NumOfBitCastUses++; 233 } 234 235 // Malloc call has 1 bitcast use, so type is the bitcast's destination type. 236 if (NumOfBitCastUses == 1) 237 return MallocType; 238 239 // Malloc call was not bitcast, so type is the malloc function's return type. 240 if (NumOfBitCastUses == 0) 241 return cast<PointerType>(CI->getType()); 242 243 // Type could not be determined. 244 return NULL; 245} 246 247/// getMallocAllocatedType - Returns the Type allocated by malloc call. 248/// The Type depends on the number of bitcast uses of the malloc call: 249/// 0: PointerType is the malloc calls' return type. 250/// 1: PointerType is the bitcast's result type. 251/// >1: Unique PointerType cannot be determined, return NULL. 252Type *llvm::getMallocAllocatedType(const CallInst *CI) { 253 PointerType *PT = getMallocType(CI); 254 return PT ? PT->getElementType() : NULL; 255} 256 257/// getMallocArraySize - Returns the array size of a malloc call. If the 258/// argument passed to malloc is a multiple of the size of the malloced type, 259/// then return that multiple. For non-array mallocs, the multiple is 260/// constant 1. Otherwise, return NULL for mallocs whose array size cannot be 261/// determined. 262Value *llvm::getMallocArraySize(CallInst *CI, const TargetData *TD, 263 bool LookThroughSExt) { 264 assert(isMallocLikeFn(CI) && "getMallocArraySize and not malloc call"); 265 return computeArraySize(CI, TD, LookThroughSExt); 266} 267 268 269/// extractCallocCall - Returns the corresponding CallInst if the instruction 270/// is a calloc call. 271const CallInst *llvm::extractCallocCall(const Value *I) { 272 return isCallocLikeFn(I) ? cast<CallInst>(I) : 0; 273} 274 275 276/// isFreeCall - Returns non-null if the value is a call to the builtin free() 277const CallInst *llvm::isFreeCall(const Value *I) { 278 const CallInst *CI = dyn_cast<CallInst>(I); 279 if (!CI) 280 return 0; 281 Function *Callee = CI->getCalledFunction(); 282 if (Callee == 0 || !Callee->isDeclaration()) 283 return 0; 284 285 if (Callee->getName() != "free" && 286 Callee->getName() != "_ZdlPv" && // operator delete(void*) 287 Callee->getName() != "_ZdaPv") // operator delete[](void*) 288 return 0; 289 290 // Check free prototype. 291 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin 292 // attribute will exist. 293 FunctionType *FTy = Callee->getFunctionType(); 294 if (!FTy->getReturnType()->isVoidTy()) 295 return 0; 296 if (FTy->getNumParams() != 1) 297 return 0; 298 if (FTy->getParamType(0) != Type::getInt8PtrTy(Callee->getContext())) 299 return 0; 300 301 return CI; 302} 303 304 305 306//===----------------------------------------------------------------------===// 307// Utility functions to compute size of objects. 308// 309 310 311/// \brief Compute the size of the object pointed by Ptr. Returns true and the 312/// object size in Size if successful, and false otherwise. 313/// If RoundToAlign is true, then Size is rounded up to the aligment of allocas, 314/// byval arguments, and global variables. 315bool llvm::getObjectSize(const Value *Ptr, uint64_t &Size, const TargetData *TD, 316 bool RoundToAlign) { 317 if (!TD) 318 return false; 319 320 ObjectSizeOffsetVisitor Visitor(TD, Ptr->getContext(), RoundToAlign); 321 SizeOffsetType Data = Visitor.compute(const_cast<Value*>(Ptr)); 322 if (!Visitor.bothKnown(Data)) 323 return false; 324 325 APInt ObjSize = Data.first, Offset = Data.second; 326 // check for overflow 327 if (Offset.slt(0) || ObjSize.ult(Offset)) 328 Size = 0; 329 else 330 Size = (ObjSize - Offset).getZExtValue(); 331 return true; 332} 333 334 335STATISTIC(ObjectVisitorArgument, 336 "Number of arguments with unsolved size and offset"); 337STATISTIC(ObjectVisitorLoad, 338 "Number of load instructions with unsolved size and offset"); 339 340 341APInt ObjectSizeOffsetVisitor::align(APInt Size, uint64_t Align) { 342 if (RoundToAlign && Align) 343 return APInt(IntTyBits, RoundUpToAlignment(Size.getZExtValue(), Align)); 344 return Size; 345} 346 347ObjectSizeOffsetVisitor::ObjectSizeOffsetVisitor(const TargetData *TD, 348 LLVMContext &Context, 349 bool RoundToAlign) 350: TD(TD), RoundToAlign(RoundToAlign) { 351 IntegerType *IntTy = TD->getIntPtrType(Context); 352 IntTyBits = IntTy->getBitWidth(); 353 Zero = APInt::getNullValue(IntTyBits); 354} 355 356SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) { 357 V = V->stripPointerCasts(); 358 359 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) 360 return visitGEPOperator(*GEP); 361 if (Instruction *I = dyn_cast<Instruction>(V)) 362 return visit(*I); 363 if (Argument *A = dyn_cast<Argument>(V)) 364 return visitArgument(*A); 365 if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V)) 366 return visitConstantPointerNull(*P); 367 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) 368 return visitGlobalVariable(*GV); 369 if (UndefValue *UV = dyn_cast<UndefValue>(V)) 370 return visitUndefValue(*UV); 371 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) 372 if (CE->getOpcode() == Instruction::IntToPtr) 373 return unknown(); // clueless 374 375 DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: " << *V 376 << '\n'); 377 return unknown(); 378} 379 380SizeOffsetType ObjectSizeOffsetVisitor::visitAllocaInst(AllocaInst &I) { 381 if (!I.getAllocatedType()->isSized()) 382 return unknown(); 383 384 APInt Size(IntTyBits, TD->getTypeAllocSize(I.getAllocatedType())); 385 if (!I.isArrayAllocation()) 386 return std::make_pair(align(Size, I.getAlignment()), Zero); 387 388 Value *ArraySize = I.getArraySize(); 389 if (const ConstantInt *C = dyn_cast<ConstantInt>(ArraySize)) { 390 Size *= C->getValue().zextOrSelf(IntTyBits); 391 return std::make_pair(align(Size, I.getAlignment()), Zero); 392 } 393 return unknown(); 394} 395 396SizeOffsetType ObjectSizeOffsetVisitor::visitArgument(Argument &A) { 397 // no interprocedural analysis is done at the moment 398 if (!A.hasByValAttr()) { 399 ++ObjectVisitorArgument; 400 return unknown(); 401 } 402 PointerType *PT = cast<PointerType>(A.getType()); 403 APInt Size(IntTyBits, TD->getTypeAllocSize(PT->getElementType())); 404 return std::make_pair(align(Size, A.getParamAlignment()), Zero); 405} 406 407SizeOffsetType ObjectSizeOffsetVisitor::visitCallSite(CallSite CS) { 408 const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc); 409 if (!FnData) 410 return unknown(); 411 412 // handle strdup-like functions separately 413 if (FnData->AllocTy == StrDupLike) { 414 // TODO 415 return unknown(); 416 } 417 418 ConstantInt *Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam)); 419 if (!Arg) 420 return unknown(); 421 422 APInt Size = Arg->getValue().zextOrSelf(IntTyBits); 423 // size determined by just 1 parameter 424 if (FnData->SndParam < 0) 425 return std::make_pair(Size, Zero); 426 427 Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->SndParam)); 428 if (!Arg) 429 return unknown(); 430 431 Size *= Arg->getValue().zextOrSelf(IntTyBits); 432 return std::make_pair(Size, Zero); 433 434 // TODO: handle more standard functions (+ wchar cousins): 435 // - strdup / strndup 436 // - strcpy / strncpy 437 // - strcat / strncat 438 // - memcpy / memmove 439 // - strcat / strncat 440 // - memset 441} 442 443SizeOffsetType 444ObjectSizeOffsetVisitor::visitConstantPointerNull(ConstantPointerNull&) { 445 return std::make_pair(Zero, Zero); 446} 447 448SizeOffsetType 449ObjectSizeOffsetVisitor::visitExtractValueInst(ExtractValueInst&) { 450 // Easy cases were already folded by previous passes. 451 return unknown(); 452} 453 454SizeOffsetType ObjectSizeOffsetVisitor::visitGEPOperator(GEPOperator &GEP) { 455 SizeOffsetType PtrData = compute(GEP.getPointerOperand()); 456 if (!bothKnown(PtrData) || !GEP.hasAllConstantIndices()) 457 return unknown(); 458 459 SmallVector<Value*, 8> Ops(GEP.idx_begin(), GEP.idx_end()); 460 APInt Offset(IntTyBits,TD->getIndexedOffset(GEP.getPointerOperandType(),Ops)); 461 return std::make_pair(PtrData.first, PtrData.second + Offset); 462} 463 464SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalVariable(GlobalVariable &GV){ 465 if (!GV.hasDefinitiveInitializer()) 466 return unknown(); 467 468 APInt Size(IntTyBits, TD->getTypeAllocSize(GV.getType()->getElementType())); 469 return std::make_pair(align(Size, GV.getAlignment()), Zero); 470} 471 472SizeOffsetType ObjectSizeOffsetVisitor::visitIntToPtrInst(IntToPtrInst&) { 473 // clueless 474 return unknown(); 475} 476 477SizeOffsetType ObjectSizeOffsetVisitor::visitLoadInst(LoadInst&) { 478 ++ObjectVisitorLoad; 479 return unknown(); 480} 481 482SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode&) { 483 // too complex to analyze statically. 484 return unknown(); 485} 486 487SizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) { 488 SizeOffsetType TrueSide = compute(I.getTrueValue()); 489 SizeOffsetType FalseSide = compute(I.getFalseValue()); 490 if (bothKnown(TrueSide) && bothKnown(FalseSide) && TrueSide == FalseSide) 491 return TrueSide; 492 return unknown(); 493} 494 495SizeOffsetType ObjectSizeOffsetVisitor::visitUndefValue(UndefValue&) { 496 return std::make_pair(Zero, Zero); 497} 498 499SizeOffsetType ObjectSizeOffsetVisitor::visitInstruction(Instruction &I) { 500 DEBUG(dbgs() << "ObjectSizeOffsetVisitor unknown instruction:" << I << '\n'); 501 return unknown(); 502} 503 504 505ObjectSizeOffsetEvaluator::ObjectSizeOffsetEvaluator(const TargetData *TD, 506 LLVMContext &Context) 507: TD(TD), Context(Context), Builder(Context, TargetFolder(TD)), 508Visitor(TD, Context) { 509 IntTy = TD->getIntPtrType(Context); 510 Zero = ConstantInt::get(IntTy, 0); 511} 512 513SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute(Value *V) { 514 SizeOffsetEvalType Result = compute_(V); 515 516 if (!bothKnown(Result)) { 517 // erase everything that was computed in this iteration from the cache, so 518 // that no dangling references are left behind. We could be a bit smarter if 519 // we kept a dependency graph. It's probably not worth the complexity. 520 for (PtrSetTy::iterator I=SeenVals.begin(), E=SeenVals.end(); I != E; ++I) { 521 CacheMapTy::iterator CacheIt = CacheMap.find(*I); 522 // non-computable results can be safely cached 523 if (CacheIt != CacheMap.end() && anyKnown(CacheIt->second)) 524 CacheMap.erase(CacheIt); 525 } 526 } 527 528 SeenVals.clear(); 529 return Result; 530} 531 532SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute_(Value *V) { 533 SizeOffsetType Const = Visitor.compute(V); 534 if (Visitor.bothKnown(Const)) 535 return std::make_pair(ConstantInt::get(Context, Const.first), 536 ConstantInt::get(Context, Const.second)); 537 538 V = V->stripPointerCasts(); 539 540 // check cache 541 CacheMapTy::iterator CacheIt = CacheMap.find(V); 542 if (CacheIt != CacheMap.end()) 543 return CacheIt->second; 544 545 // always generate code immediately before the instruction being 546 // processed, so that the generated code dominates the same BBs 547 Instruction *PrevInsertPoint = Builder.GetInsertPoint(); 548 if (Instruction *I = dyn_cast<Instruction>(V)) 549 Builder.SetInsertPoint(I); 550 551 // record the pointers that were handled in this run, so that they can be 552 // cleaned later if something fails 553 SeenVals.insert(V); 554 555 // now compute the size and offset 556 SizeOffsetEvalType Result; 557 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { 558 Result = visitGEPOperator(*GEP); 559 } else if (Instruction *I = dyn_cast<Instruction>(V)) { 560 Result = visit(*I); 561 } else if (isa<Argument>(V) || 562 (isa<ConstantExpr>(V) && 563 cast<ConstantExpr>(V)->getOpcode() == Instruction::IntToPtr) || 564 isa<GlobalVariable>(V)) { 565 // ignore values where we cannot do more than what ObjectSizeVisitor can 566 Result = unknown(); 567 } else { 568 DEBUG(dbgs() << "ObjectSizeOffsetEvaluator::compute() unhandled value: " 569 << *V << '\n'); 570 Result = unknown(); 571 } 572 573 if (PrevInsertPoint) 574 Builder.SetInsertPoint(PrevInsertPoint); 575 576 // Don't reuse CacheIt since it may be invalid at this point. 577 CacheMap[V] = Result; 578 return Result; 579} 580 581SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitAllocaInst(AllocaInst &I) { 582 if (!I.getAllocatedType()->isSized()) 583 return unknown(); 584 585 // must be a VLA 586 assert(I.isArrayAllocation()); 587 Value *ArraySize = I.getArraySize(); 588 Value *Size = ConstantInt::get(ArraySize->getType(), 589 TD->getTypeAllocSize(I.getAllocatedType())); 590 Size = Builder.CreateMul(Size, ArraySize); 591 return std::make_pair(Size, Zero); 592} 593 594SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitCallSite(CallSite CS) { 595 const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc); 596 if (!FnData) 597 return unknown(); 598 599 // handle strdup-like functions separately 600 if (FnData->AllocTy == StrDupLike) { 601 // TODO 602 return unknown(); 603 } 604 605 Value *FirstArg = CS.getArgument(FnData->FstParam); 606 FirstArg = Builder.CreateZExt(FirstArg, IntTy); 607 if (FnData->SndParam < 0) 608 return std::make_pair(FirstArg, Zero); 609 610 Value *SecondArg = CS.getArgument(FnData->SndParam); 611 SecondArg = Builder.CreateZExt(SecondArg, IntTy); 612 Value *Size = Builder.CreateMul(FirstArg, SecondArg); 613 return std::make_pair(Size, Zero); 614 615 // TODO: handle more standard functions (+ wchar cousins): 616 // - strdup / strndup 617 // - strcpy / strncpy 618 // - strcat / strncat 619 // - memcpy / memmove 620 // - strcat / strncat 621 // - memset 622} 623 624SizeOffsetEvalType 625ObjectSizeOffsetEvaluator::visitGEPOperator(GEPOperator &GEP) { 626 SizeOffsetEvalType PtrData = compute_(GEP.getPointerOperand()); 627 if (!bothKnown(PtrData)) 628 return unknown(); 629 630 Value *Offset = EmitGEPOffset(&Builder, *TD, &GEP); 631 Offset = Builder.CreateAdd(PtrData.second, Offset); 632 return std::make_pair(PtrData.first, Offset); 633} 634 635SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitIntToPtrInst(IntToPtrInst&) { 636 // clueless 637 return unknown(); 638} 639 640SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitLoadInst(LoadInst&) { 641 return unknown(); 642} 643 644SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitPHINode(PHINode &PHI) { 645 // create 2 PHIs: one for size and another for offset 646 PHINode *SizePHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues()); 647 PHINode *OffsetPHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues()); 648 649 // insert right away in the cache to handle recursive PHIs 650 CacheMap[&PHI] = std::make_pair(SizePHI, OffsetPHI); 651 652 // compute offset/size for each PHI incoming pointer 653 for (unsigned i = 0, e = PHI.getNumIncomingValues(); i != e; ++i) { 654 Builder.SetInsertPoint(PHI.getIncomingBlock(i)->getFirstInsertionPt()); 655 SizeOffsetEvalType EdgeData = compute_(PHI.getIncomingValue(i)); 656 657 if (!bothKnown(EdgeData)) { 658 OffsetPHI->replaceAllUsesWith(UndefValue::get(IntTy)); 659 OffsetPHI->eraseFromParent(); 660 SizePHI->replaceAllUsesWith(UndefValue::get(IntTy)); 661 SizePHI->eraseFromParent(); 662 return unknown(); 663 } 664 SizePHI->addIncoming(EdgeData.first, PHI.getIncomingBlock(i)); 665 OffsetPHI->addIncoming(EdgeData.second, PHI.getIncomingBlock(i)); 666 } 667 return std::make_pair(SizePHI, OffsetPHI); 668} 669 670SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitSelectInst(SelectInst &I) { 671 SizeOffsetEvalType TrueSide = compute_(I.getTrueValue()); 672 SizeOffsetEvalType FalseSide = compute_(I.getFalseValue()); 673 674 if (!bothKnown(TrueSide) || !bothKnown(FalseSide)) 675 return unknown(); 676 if (TrueSide == FalseSide) 677 return TrueSide; 678 679 Value *Size = Builder.CreateSelect(I.getCondition(), TrueSide.first, 680 FalseSide.first); 681 Value *Offset = Builder.CreateSelect(I.getCondition(), TrueSide.second, 682 FalseSide.second); 683 return std::make_pair(Size, Offset); 684} 685 686SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitInstruction(Instruction &I) { 687 DEBUG(dbgs() << "ObjectSizeOffsetEvaluator unknown instruction:" << I <<'\n'); 688 return unknown(); 689} 690