1198892Srdivacky//===------ MemoryBuiltins.cpp - Identify calls to memory builtins --------===// 2198892Srdivacky// 3198892Srdivacky// The LLVM Compiler Infrastructure 4198892Srdivacky// 5198892Srdivacky// This file is distributed under the University of Illinois Open Source 6198892Srdivacky// License. See LICENSE.TXT for details. 7198892Srdivacky// 8198892Srdivacky//===----------------------------------------------------------------------===// 9198892Srdivacky// 10198892Srdivacky// This family of functions identifies calls to builtin functions that allocate 11252723Sdim// or free memory. 12198892Srdivacky// 13198892Srdivacky//===----------------------------------------------------------------------===// 14198892Srdivacky 15245431Sdim#define DEBUG_TYPE "memory-builtins" 16252723Sdim#include "llvm/Analysis/MemoryBuiltins.h" 17252723Sdim#include "llvm/ADT/STLExtras.h" 18245431Sdim#include "llvm/ADT/Statistic.h" 19199481Srdivacky#include "llvm/Analysis/ValueTracking.h" 20252723Sdim#include "llvm/IR/DataLayout.h" 21252723Sdim#include "llvm/IR/GlobalVariable.h" 22252723Sdim#include "llvm/IR/Instructions.h" 23252723Sdim#include "llvm/IR/Intrinsics.h" 24252723Sdim#include "llvm/IR/Metadata.h" 25252723Sdim#include "llvm/IR/Module.h" 26245431Sdim#include "llvm/Support/Debug.h" 27245431Sdim#include "llvm/Support/MathExtras.h" 28245431Sdim#include "llvm/Support/raw_ostream.h" 29245431Sdim#include "llvm/Target/TargetLibraryInfo.h" 30245431Sdim#include "llvm/Transforms/Utils/Local.h" 31198892Srdivackyusing namespace llvm; 32198892Srdivacky 33245431Sdimenum AllocType { 34263509Sdim OpNewLike = 1<<0, // allocates; never returns null 35263509Sdim MallocLike = 1<<1 | OpNewLike, // allocates; may return null 36263509Sdim CallocLike = 1<<2, // allocates + bzero 37263509Sdim ReallocLike = 1<<3, // reallocates 38263509Sdim StrDupLike = 1<<4, 39245431Sdim AllocLike = MallocLike | CallocLike | StrDupLike, 40263509Sdim AnyAlloc = AllocLike | ReallocLike 41245431Sdim}; 42198892Srdivacky 43245431Sdimstruct AllocFnsTy { 44245431Sdim LibFunc::Func Func; 45245431Sdim AllocType AllocTy; 46245431Sdim unsigned char NumParams; 47245431Sdim // First and Second size parameters (or -1 if unused) 48245431Sdim signed char FstParam, SndParam; 49245431Sdim}; 50245431Sdim 51245431Sdim// FIXME: certain users need more information. E.g., SimplifyLibCalls needs to 52245431Sdim// know which functions are nounwind, noalias, nocapture parameters, etc. 53245431Sdimstatic const AllocFnsTy AllocationFnData[] = { 54245431Sdim {LibFunc::malloc, MallocLike, 1, 0, -1}, 55245431Sdim {LibFunc::valloc, MallocLike, 1, 0, -1}, 56263509Sdim {LibFunc::Znwj, OpNewLike, 1, 0, -1}, // new(unsigned int) 57245431Sdim {LibFunc::ZnwjRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new(unsigned int, nothrow) 58263509Sdim {LibFunc::Znwm, OpNewLike, 1, 0, -1}, // new(unsigned long) 59245431Sdim {LibFunc::ZnwmRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new(unsigned long, nothrow) 60263509Sdim {LibFunc::Znaj, OpNewLike, 1, 0, -1}, // new[](unsigned int) 61245431Sdim {LibFunc::ZnajRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new[](unsigned int, nothrow) 62263509Sdim {LibFunc::Znam, OpNewLike, 1, 0, -1}, // new[](unsigned long) 63245431Sdim {LibFunc::ZnamRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new[](unsigned long, nothrow) 64245431Sdim {LibFunc::calloc, CallocLike, 2, 0, 1}, 65245431Sdim {LibFunc::realloc, ReallocLike, 2, 1, -1}, 66245431Sdim {LibFunc::reallocf, ReallocLike, 2, 1, -1}, 67245431Sdim {LibFunc::strdup, StrDupLike, 1, -1, -1}, 68245431Sdim {LibFunc::strndup, StrDupLike, 2, 1, -1} 69263509Sdim // TODO: Handle "int posix_memalign(void **, size_t, size_t)" 70245431Sdim}; 71245431Sdim 72245431Sdim 73245431Sdimstatic Function *getCalledFunction(const Value *V, bool LookThroughBitCast) { 74245431Sdim if (LookThroughBitCast) 75245431Sdim V = V->stripPointerCasts(); 76245431Sdim 77245431Sdim CallSite CS(const_cast<Value*>(V)); 78245431Sdim if (!CS.getInstruction()) 79245431Sdim return 0; 80245431Sdim 81263509Sdim if (CS.isNoBuiltin()) 82263509Sdim return 0; 83263509Sdim 84245431Sdim Function *Callee = CS.getCalledFunction(); 85245431Sdim if (!Callee || !Callee->isDeclaration()) 86245431Sdim return 0; 87245431Sdim return Callee; 88198892Srdivacky} 89198892Srdivacky 90245431Sdim/// \brief Returns the allocation data for the given value if it is a call to a 91245431Sdim/// known allocation function, and NULL otherwise. 92245431Sdimstatic const AllocFnsTy *getAllocationData(const Value *V, AllocType AllocTy, 93245431Sdim const TargetLibraryInfo *TLI, 94245431Sdim bool LookThroughBitCast = false) { 95252723Sdim // Skip intrinsics 96252723Sdim if (isa<IntrinsicInst>(V)) 97252723Sdim return 0; 98252723Sdim 99245431Sdim Function *Callee = getCalledFunction(V, LookThroughBitCast); 100245431Sdim if (!Callee) 101245431Sdim return 0; 102198892Srdivacky 103245431Sdim // Make sure that the function is available. 104245431Sdim StringRef FnName = Callee->getName(); 105245431Sdim LibFunc::Func TLIFn; 106245431Sdim if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn)) 107245431Sdim return 0; 108198892Srdivacky 109245431Sdim unsigned i = 0; 110245431Sdim bool found = false; 111245431Sdim for ( ; i < array_lengthof(AllocationFnData); ++i) { 112245431Sdim if (AllocationFnData[i].Func == TLIFn) { 113245431Sdim found = true; 114245431Sdim break; 115245431Sdim } 116245431Sdim } 117245431Sdim if (!found) 118245431Sdim return 0; 119245431Sdim 120245431Sdim const AllocFnsTy *FnData = &AllocationFnData[i]; 121263509Sdim if ((FnData->AllocTy & AllocTy) != FnData->AllocTy) 122245431Sdim return 0; 123245431Sdim 124245431Sdim // Check function prototype. 125245431Sdim int FstParam = FnData->FstParam; 126245431Sdim int SndParam = FnData->SndParam; 127226890Sdim FunctionType *FTy = Callee->getFunctionType(); 128245431Sdim 129245431Sdim if (FTy->getReturnType() == Type::getInt8PtrTy(FTy->getContext()) && 130245431Sdim FTy->getNumParams() == FnData->NumParams && 131245431Sdim (FstParam < 0 || 132245431Sdim (FTy->getParamType(FstParam)->isIntegerTy(32) || 133245431Sdim FTy->getParamType(FstParam)->isIntegerTy(64))) && 134245431Sdim (SndParam < 0 || 135245431Sdim FTy->getParamType(SndParam)->isIntegerTy(32) || 136245431Sdim FTy->getParamType(SndParam)->isIntegerTy(64))) 137245431Sdim return FnData; 138245431Sdim return 0; 139198892Srdivacky} 140198892Srdivacky 141245431Sdimstatic bool hasNoAliasAttr(const Value *V, bool LookThroughBitCast) { 142245431Sdim ImmutableCallSite CS(LookThroughBitCast ? V->stripPointerCasts() : V); 143252723Sdim return CS && CS.hasFnAttr(Attribute::NoAlias); 144198892Srdivacky} 145198892Srdivacky 146245431Sdim 147245431Sdim/// \brief Tests if a value is a call or invoke to a library function that 148245431Sdim/// allocates or reallocates memory (either malloc, calloc, realloc, or strdup 149245431Sdim/// like). 150245431Sdimbool llvm::isAllocationFn(const Value *V, const TargetLibraryInfo *TLI, 151245431Sdim bool LookThroughBitCast) { 152245431Sdim return getAllocationData(V, AnyAlloc, TLI, LookThroughBitCast); 153198892Srdivacky} 154198892Srdivacky 155245431Sdim/// \brief Tests if a value is a call or invoke to a function that returns a 156245431Sdim/// NoAlias pointer (including malloc/calloc/realloc/strdup-like functions). 157245431Sdimbool llvm::isNoAliasFn(const Value *V, const TargetLibraryInfo *TLI, 158245431Sdim bool LookThroughBitCast) { 159245431Sdim // it's safe to consider realloc as noalias since accessing the original 160245431Sdim // pointer is undefined behavior 161245431Sdim return isAllocationFn(V, TLI, LookThroughBitCast) || 162245431Sdim hasNoAliasAttr(V, LookThroughBitCast); 163198892Srdivacky} 164198892Srdivacky 165245431Sdim/// \brief Tests if a value is a call or invoke to a library function that 166245431Sdim/// allocates uninitialized memory (such as malloc). 167245431Sdimbool llvm::isMallocLikeFn(const Value *V, const TargetLibraryInfo *TLI, 168245431Sdim bool LookThroughBitCast) { 169245431Sdim return getAllocationData(V, MallocLike, TLI, LookThroughBitCast); 170198892Srdivacky} 171198892Srdivacky 172245431Sdim/// \brief Tests if a value is a call or invoke to a library function that 173245431Sdim/// allocates zero-filled memory (such as calloc). 174245431Sdimbool llvm::isCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI, 175245431Sdim bool LookThroughBitCast) { 176245431Sdim return getAllocationData(V, CallocLike, TLI, LookThroughBitCast); 177198892Srdivacky} 178198892Srdivacky 179245431Sdim/// \brief Tests if a value is a call or invoke to a library function that 180245431Sdim/// allocates memory (either malloc, calloc, or strdup like). 181245431Sdimbool llvm::isAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI, 182245431Sdim bool LookThroughBitCast) { 183245431Sdim return getAllocationData(V, AllocLike, TLI, LookThroughBitCast); 184245431Sdim} 185245431Sdim 186245431Sdim/// \brief Tests if a value is a call or invoke to a library function that 187245431Sdim/// reallocates memory (such as realloc). 188245431Sdimbool llvm::isReallocLikeFn(const Value *V, const TargetLibraryInfo *TLI, 189245431Sdim bool LookThroughBitCast) { 190245431Sdim return getAllocationData(V, ReallocLike, TLI, LookThroughBitCast); 191245431Sdim} 192245431Sdim 193263509Sdim/// \brief Tests if a value is a call or invoke to a library function that 194263509Sdim/// allocates memory and never returns null (such as operator new). 195263509Sdimbool llvm::isOperatorNewLikeFn(const Value *V, const TargetLibraryInfo *TLI, 196263509Sdim bool LookThroughBitCast) { 197263509Sdim return getAllocationData(V, OpNewLike, TLI, LookThroughBitCast); 198263509Sdim} 199263509Sdim 200245431Sdim/// extractMallocCall - Returns the corresponding CallInst if the instruction 201245431Sdim/// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we 202245431Sdim/// ignore InvokeInst here. 203245431Sdimconst CallInst *llvm::extractMallocCall(const Value *I, 204245431Sdim const TargetLibraryInfo *TLI) { 205245431Sdim return isMallocLikeFn(I, TLI) ? dyn_cast<CallInst>(I) : 0; 206245431Sdim} 207245431Sdim 208263509Sdimstatic Value *computeArraySize(const CallInst *CI, const DataLayout *DL, 209245431Sdim const TargetLibraryInfo *TLI, 210199481Srdivacky bool LookThroughSExt = false) { 211198892Srdivacky if (!CI) 212252723Sdim return 0; 213198892Srdivacky 214198953Srdivacky // The size of the malloc's result type must be known to determine array size. 215245431Sdim Type *T = getMallocAllocatedType(CI, TLI); 216263509Sdim if (!T || !T->isSized() || !DL) 217252723Sdim return 0; 218198892Srdivacky 219263509Sdim unsigned ElementSize = DL->getTypeAllocSize(T); 220226890Sdim if (StructType *ST = dyn_cast<StructType>(T)) 221263509Sdim ElementSize = DL->getStructLayout(ST)->getSizeInBytes(); 222198892Srdivacky 223210299Sed // If malloc call's arg can be determined to be a multiple of ElementSize, 224199481Srdivacky // return the multiple. Otherwise, return NULL. 225210299Sed Value *MallocArg = CI->getArgOperand(0); 226252723Sdim Value *Multiple = 0; 227199481Srdivacky if (ComputeMultiple(MallocArg, ElementSize, Multiple, 228199481Srdivacky LookThroughSExt)) 229199481Srdivacky return Multiple; 230198892Srdivacky 231252723Sdim return 0; 232198892Srdivacky} 233198892Srdivacky 234252723Sdim/// isArrayMalloc - Returns the corresponding CallInst if the instruction 235198892Srdivacky/// is a call to malloc whose array size can be determined and the array size 236198892Srdivacky/// is not constant 1. Otherwise, return NULL. 237245431Sdimconst CallInst *llvm::isArrayMalloc(const Value *I, 238263509Sdim const DataLayout *DL, 239245431Sdim const TargetLibraryInfo *TLI) { 240245431Sdim const CallInst *CI = extractMallocCall(I, TLI); 241263509Sdim Value *ArraySize = computeArraySize(CI, DL, TLI); 242198892Srdivacky 243252723Sdim if (ConstantInt *ConstSize = dyn_cast_or_null<ConstantInt>(ArraySize)) 244252723Sdim if (ConstSize->isOne()) 245252723Sdim return CI; 246198892Srdivacky 247198892Srdivacky // CI is a non-array malloc or we can't figure out that it is an array malloc. 248252723Sdim return 0; 249198892Srdivacky} 250198892Srdivacky 251198892Srdivacky/// getMallocType - Returns the PointerType resulting from the malloc call. 252198953Srdivacky/// The PointerType depends on the number of bitcast uses of the malloc call: 253198953Srdivacky/// 0: PointerType is the calls' return type. 254198953Srdivacky/// 1: PointerType is the bitcast's result type. 255198953Srdivacky/// >1: Unique PointerType cannot be determined, return NULL. 256245431SdimPointerType *llvm::getMallocType(const CallInst *CI, 257245431Sdim const TargetLibraryInfo *TLI) { 258245431Sdim assert(isMallocLikeFn(CI, TLI) && "getMallocType and not malloc call"); 259252723Sdim 260252723Sdim PointerType *MallocType = 0; 261198953Srdivacky unsigned NumOfBitCastUses = 0; 262198953Srdivacky 263198892Srdivacky // Determine if CallInst has a bitcast use. 264206083Srdivacky for (Value::const_use_iterator UI = CI->use_begin(), E = CI->use_end(); 265198892Srdivacky UI != E; ) 266198953Srdivacky if (const BitCastInst *BCI = dyn_cast<BitCastInst>(*UI++)) { 267198953Srdivacky MallocType = cast<PointerType>(BCI->getDestTy()); 268198953Srdivacky NumOfBitCastUses++; 269198953Srdivacky } 270198892Srdivacky 271198953Srdivacky // Malloc call has 1 bitcast use, so type is the bitcast's destination type. 272198953Srdivacky if (NumOfBitCastUses == 1) 273198953Srdivacky return MallocType; 274198892Srdivacky 275198892Srdivacky // Malloc call was not bitcast, so type is the malloc function's return type. 276198953Srdivacky if (NumOfBitCastUses == 0) 277198892Srdivacky return cast<PointerType>(CI->getType()); 278198892Srdivacky 279198892Srdivacky // Type could not be determined. 280252723Sdim return 0; 281198892Srdivacky} 282198892Srdivacky 283198953Srdivacky/// getMallocAllocatedType - Returns the Type allocated by malloc call. 284198953Srdivacky/// The Type depends on the number of bitcast uses of the malloc call: 285198953Srdivacky/// 0: PointerType is the malloc calls' return type. 286198953Srdivacky/// 1: PointerType is the bitcast's result type. 287198953Srdivacky/// >1: Unique PointerType cannot be determined, return NULL. 288245431SdimType *llvm::getMallocAllocatedType(const CallInst *CI, 289245431Sdim const TargetLibraryInfo *TLI) { 290245431Sdim PointerType *PT = getMallocType(CI, TLI); 291252723Sdim return PT ? PT->getElementType() : 0; 292198892Srdivacky} 293198892Srdivacky 294252723Sdim/// getMallocArraySize - Returns the array size of a malloc call. If the 295198892Srdivacky/// argument passed to malloc is a multiple of the size of the malloced type, 296198892Srdivacky/// then return that multiple. For non-array mallocs, the multiple is 297198892Srdivacky/// constant 1. Otherwise, return NULL for mallocs whose array size cannot be 298198892Srdivacky/// determined. 299263509SdimValue *llvm::getMallocArraySize(CallInst *CI, const DataLayout *DL, 300245431Sdim const TargetLibraryInfo *TLI, 301199481Srdivacky bool LookThroughSExt) { 302245431Sdim assert(isMallocLikeFn(CI, TLI) && "getMallocArraySize and not malloc call"); 303263509Sdim return computeArraySize(CI, DL, TLI, LookThroughSExt); 304198892Srdivacky} 305198892Srdivacky 306198892Srdivacky 307245431Sdim/// extractCallocCall - Returns the corresponding CallInst if the instruction 308245431Sdim/// is a calloc call. 309245431Sdimconst CallInst *llvm::extractCallocCall(const Value *I, 310245431Sdim const TargetLibraryInfo *TLI) { 311245431Sdim return isCallocLikeFn(I, TLI) ? cast<CallInst>(I) : 0; 312245431Sdim} 313245431Sdim 314245431Sdim 315210299Sed/// isFreeCall - Returns non-null if the value is a call to the builtin free() 316245431Sdimconst CallInst *llvm::isFreeCall(const Value *I, const TargetLibraryInfo *TLI) { 317198892Srdivacky const CallInst *CI = dyn_cast<CallInst>(I); 318252723Sdim if (!CI || isa<IntrinsicInst>(CI)) 319210299Sed return 0; 320198892Srdivacky Function *Callee = CI->getCalledFunction(); 321221345Sdim if (Callee == 0 || !Callee->isDeclaration()) 322210299Sed return 0; 323198892Srdivacky 324245431Sdim StringRef FnName = Callee->getName(); 325245431Sdim LibFunc::Func TLIFn; 326245431Sdim if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn)) 327221345Sdim return 0; 328221345Sdim 329263509Sdim unsigned ExpectedNumParams; 330263509Sdim if (TLIFn == LibFunc::free || 331263509Sdim TLIFn == LibFunc::ZdlPv || // operator delete(void*) 332263509Sdim TLIFn == LibFunc::ZdaPv) // operator delete[](void*) 333263509Sdim ExpectedNumParams = 1; 334263509Sdim else if (TLIFn == LibFunc::ZdlPvRKSt9nothrow_t || // delete(void*, nothrow) 335263509Sdim TLIFn == LibFunc::ZdaPvRKSt9nothrow_t) // delete[](void*, nothrow) 336263509Sdim ExpectedNumParams = 2; 337263509Sdim else 338245431Sdim return 0; 339245431Sdim 340198892Srdivacky // Check free prototype. 341252723Sdim // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin 342198892Srdivacky // attribute will exist. 343226890Sdim FunctionType *FTy = Callee->getFunctionType(); 344198892Srdivacky if (!FTy->getReturnType()->isVoidTy()) 345210299Sed return 0; 346263509Sdim if (FTy->getNumParams() != ExpectedNumParams) 347210299Sed return 0; 348224145Sdim if (FTy->getParamType(0) != Type::getInt8PtrTy(Callee->getContext())) 349210299Sed return 0; 350198892Srdivacky 351210299Sed return CI; 352198892Srdivacky} 353245431Sdim 354245431Sdim 355245431Sdim 356245431Sdim//===----------------------------------------------------------------------===// 357245431Sdim// Utility functions to compute size of objects. 358245431Sdim// 359245431Sdim 360245431Sdim 361245431Sdim/// \brief Compute the size of the object pointed by Ptr. Returns true and the 362245431Sdim/// object size in Size if successful, and false otherwise. 363245431Sdim/// If RoundToAlign is true, then Size is rounded up to the aligment of allocas, 364245431Sdim/// byval arguments, and global variables. 365263509Sdimbool llvm::getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout *DL, 366245431Sdim const TargetLibraryInfo *TLI, bool RoundToAlign) { 367263509Sdim if (!DL) 368245431Sdim return false; 369245431Sdim 370263509Sdim ObjectSizeOffsetVisitor Visitor(DL, TLI, Ptr->getContext(), RoundToAlign); 371245431Sdim SizeOffsetType Data = Visitor.compute(const_cast<Value*>(Ptr)); 372245431Sdim if (!Visitor.bothKnown(Data)) 373245431Sdim return false; 374245431Sdim 375245431Sdim APInt ObjSize = Data.first, Offset = Data.second; 376245431Sdim // check for overflow 377245431Sdim if (Offset.slt(0) || ObjSize.ult(Offset)) 378245431Sdim Size = 0; 379245431Sdim else 380245431Sdim Size = (ObjSize - Offset).getZExtValue(); 381245431Sdim return true; 382245431Sdim} 383245431Sdim 384245431Sdim 385245431SdimSTATISTIC(ObjectVisitorArgument, 386245431Sdim "Number of arguments with unsolved size and offset"); 387245431SdimSTATISTIC(ObjectVisitorLoad, 388245431Sdim "Number of load instructions with unsolved size and offset"); 389245431Sdim 390245431Sdim 391245431SdimAPInt ObjectSizeOffsetVisitor::align(APInt Size, uint64_t Align) { 392245431Sdim if (RoundToAlign && Align) 393245431Sdim return APInt(IntTyBits, RoundUpToAlignment(Size.getZExtValue(), Align)); 394245431Sdim return Size; 395245431Sdim} 396245431Sdim 397263509SdimObjectSizeOffsetVisitor::ObjectSizeOffsetVisitor(const DataLayout *DL, 398245431Sdim const TargetLibraryInfo *TLI, 399245431Sdim LLVMContext &Context, 400245431Sdim bool RoundToAlign) 401263509Sdim: DL(DL), TLI(TLI), RoundToAlign(RoundToAlign) { 402263509Sdim IntegerType *IntTy = DL->getIntPtrType(Context); 403245431Sdim IntTyBits = IntTy->getBitWidth(); 404245431Sdim Zero = APInt::getNullValue(IntTyBits); 405245431Sdim} 406245431Sdim 407245431SdimSizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) { 408245431Sdim V = V->stripPointerCasts(); 409245431Sdim if (Instruction *I = dyn_cast<Instruction>(V)) { 410245431Sdim // If we have already seen this instruction, bail out. Cycles can happen in 411245431Sdim // unreachable code after constant propagation. 412245431Sdim if (!SeenInsts.insert(I)) 413245431Sdim return unknown(); 414245431Sdim 415245431Sdim if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) 416245431Sdim return visitGEPOperator(*GEP); 417245431Sdim return visit(*I); 418245431Sdim } 419245431Sdim if (Argument *A = dyn_cast<Argument>(V)) 420245431Sdim return visitArgument(*A); 421245431Sdim if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V)) 422245431Sdim return visitConstantPointerNull(*P); 423252723Sdim if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) 424252723Sdim return visitGlobalAlias(*GA); 425245431Sdim if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) 426245431Sdim return visitGlobalVariable(*GV); 427245431Sdim if (UndefValue *UV = dyn_cast<UndefValue>(V)) 428245431Sdim return visitUndefValue(*UV); 429245431Sdim if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 430245431Sdim if (CE->getOpcode() == Instruction::IntToPtr) 431245431Sdim return unknown(); // clueless 432245431Sdim if (CE->getOpcode() == Instruction::GetElementPtr) 433245431Sdim return visitGEPOperator(cast<GEPOperator>(*CE)); 434245431Sdim } 435245431Sdim 436245431Sdim DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: " << *V 437245431Sdim << '\n'); 438245431Sdim return unknown(); 439245431Sdim} 440245431Sdim 441245431SdimSizeOffsetType ObjectSizeOffsetVisitor::visitAllocaInst(AllocaInst &I) { 442245431Sdim if (!I.getAllocatedType()->isSized()) 443245431Sdim return unknown(); 444245431Sdim 445263509Sdim APInt Size(IntTyBits, DL->getTypeAllocSize(I.getAllocatedType())); 446245431Sdim if (!I.isArrayAllocation()) 447245431Sdim return std::make_pair(align(Size, I.getAlignment()), Zero); 448245431Sdim 449245431Sdim Value *ArraySize = I.getArraySize(); 450245431Sdim if (const ConstantInt *C = dyn_cast<ConstantInt>(ArraySize)) { 451245431Sdim Size *= C->getValue().zextOrSelf(IntTyBits); 452245431Sdim return std::make_pair(align(Size, I.getAlignment()), Zero); 453245431Sdim } 454245431Sdim return unknown(); 455245431Sdim} 456245431Sdim 457245431SdimSizeOffsetType ObjectSizeOffsetVisitor::visitArgument(Argument &A) { 458245431Sdim // no interprocedural analysis is done at the moment 459245431Sdim if (!A.hasByValAttr()) { 460245431Sdim ++ObjectVisitorArgument; 461245431Sdim return unknown(); 462245431Sdim } 463245431Sdim PointerType *PT = cast<PointerType>(A.getType()); 464263509Sdim APInt Size(IntTyBits, DL->getTypeAllocSize(PT->getElementType())); 465245431Sdim return std::make_pair(align(Size, A.getParamAlignment()), Zero); 466245431Sdim} 467245431Sdim 468245431SdimSizeOffsetType ObjectSizeOffsetVisitor::visitCallSite(CallSite CS) { 469245431Sdim const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc, 470245431Sdim TLI); 471245431Sdim if (!FnData) 472245431Sdim return unknown(); 473245431Sdim 474245431Sdim // handle strdup-like functions separately 475245431Sdim if (FnData->AllocTy == StrDupLike) { 476245431Sdim APInt Size(IntTyBits, GetStringLength(CS.getArgument(0))); 477245431Sdim if (!Size) 478245431Sdim return unknown(); 479245431Sdim 480245431Sdim // strndup limits strlen 481245431Sdim if (FnData->FstParam > 0) { 482245431Sdim ConstantInt *Arg= dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam)); 483245431Sdim if (!Arg) 484245431Sdim return unknown(); 485245431Sdim 486245431Sdim APInt MaxSize = Arg->getValue().zextOrSelf(IntTyBits); 487245431Sdim if (Size.ugt(MaxSize)) 488245431Sdim Size = MaxSize + 1; 489245431Sdim } 490245431Sdim return std::make_pair(Size, Zero); 491245431Sdim } 492245431Sdim 493245431Sdim ConstantInt *Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam)); 494245431Sdim if (!Arg) 495245431Sdim return unknown(); 496245431Sdim 497245431Sdim APInt Size = Arg->getValue().zextOrSelf(IntTyBits); 498245431Sdim // size determined by just 1 parameter 499245431Sdim if (FnData->SndParam < 0) 500245431Sdim return std::make_pair(Size, Zero); 501245431Sdim 502245431Sdim Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->SndParam)); 503245431Sdim if (!Arg) 504245431Sdim return unknown(); 505245431Sdim 506245431Sdim Size *= Arg->getValue().zextOrSelf(IntTyBits); 507245431Sdim return std::make_pair(Size, Zero); 508245431Sdim 509245431Sdim // TODO: handle more standard functions (+ wchar cousins): 510245431Sdim // - strdup / strndup 511245431Sdim // - strcpy / strncpy 512245431Sdim // - strcat / strncat 513245431Sdim // - memcpy / memmove 514245431Sdim // - strcat / strncat 515245431Sdim // - memset 516245431Sdim} 517245431Sdim 518245431SdimSizeOffsetType 519245431SdimObjectSizeOffsetVisitor::visitConstantPointerNull(ConstantPointerNull&) { 520245431Sdim return std::make_pair(Zero, Zero); 521245431Sdim} 522245431Sdim 523245431SdimSizeOffsetType 524245431SdimObjectSizeOffsetVisitor::visitExtractElementInst(ExtractElementInst&) { 525245431Sdim return unknown(); 526245431Sdim} 527245431Sdim 528245431SdimSizeOffsetType 529245431SdimObjectSizeOffsetVisitor::visitExtractValueInst(ExtractValueInst&) { 530245431Sdim // Easy cases were already folded by previous passes. 531245431Sdim return unknown(); 532245431Sdim} 533245431Sdim 534245431SdimSizeOffsetType ObjectSizeOffsetVisitor::visitGEPOperator(GEPOperator &GEP) { 535245431Sdim SizeOffsetType PtrData = compute(GEP.getPointerOperand()); 536252723Sdim APInt Offset(IntTyBits, 0); 537263509Sdim if (!bothKnown(PtrData) || !GEP.accumulateConstantOffset(*DL, Offset)) 538245431Sdim return unknown(); 539245431Sdim 540245431Sdim return std::make_pair(PtrData.first, PtrData.second + Offset); 541245431Sdim} 542245431Sdim 543252723SdimSizeOffsetType ObjectSizeOffsetVisitor::visitGlobalAlias(GlobalAlias &GA) { 544252723Sdim if (GA.mayBeOverridden()) 545252723Sdim return unknown(); 546252723Sdim return compute(GA.getAliasee()); 547252723Sdim} 548252723Sdim 549245431SdimSizeOffsetType ObjectSizeOffsetVisitor::visitGlobalVariable(GlobalVariable &GV){ 550245431Sdim if (!GV.hasDefinitiveInitializer()) 551245431Sdim return unknown(); 552245431Sdim 553263509Sdim APInt Size(IntTyBits, DL->getTypeAllocSize(GV.getType()->getElementType())); 554245431Sdim return std::make_pair(align(Size, GV.getAlignment()), Zero); 555245431Sdim} 556245431Sdim 557245431SdimSizeOffsetType ObjectSizeOffsetVisitor::visitIntToPtrInst(IntToPtrInst&) { 558245431Sdim // clueless 559245431Sdim return unknown(); 560245431Sdim} 561245431Sdim 562245431SdimSizeOffsetType ObjectSizeOffsetVisitor::visitLoadInst(LoadInst&) { 563245431Sdim ++ObjectVisitorLoad; 564245431Sdim return unknown(); 565245431Sdim} 566245431Sdim 567245431SdimSizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode&) { 568245431Sdim // too complex to analyze statically. 569245431Sdim return unknown(); 570245431Sdim} 571245431Sdim 572245431SdimSizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) { 573245431Sdim SizeOffsetType TrueSide = compute(I.getTrueValue()); 574245431Sdim SizeOffsetType FalseSide = compute(I.getFalseValue()); 575245431Sdim if (bothKnown(TrueSide) && bothKnown(FalseSide) && TrueSide == FalseSide) 576245431Sdim return TrueSide; 577245431Sdim return unknown(); 578245431Sdim} 579245431Sdim 580245431SdimSizeOffsetType ObjectSizeOffsetVisitor::visitUndefValue(UndefValue&) { 581245431Sdim return std::make_pair(Zero, Zero); 582245431Sdim} 583245431Sdim 584245431SdimSizeOffsetType ObjectSizeOffsetVisitor::visitInstruction(Instruction &I) { 585245431Sdim DEBUG(dbgs() << "ObjectSizeOffsetVisitor unknown instruction:" << I << '\n'); 586245431Sdim return unknown(); 587245431Sdim} 588245431Sdim 589263509SdimObjectSizeOffsetEvaluator::ObjectSizeOffsetEvaluator(const DataLayout *DL, 590263509Sdim const TargetLibraryInfo *TLI, 591263509Sdim LLVMContext &Context, 592263509Sdim bool RoundToAlign) 593263509Sdim: DL(DL), TLI(TLI), Context(Context), Builder(Context, TargetFolder(DL)), 594263509Sdim RoundToAlign(RoundToAlign) { 595263509Sdim IntTy = DL->getIntPtrType(Context); 596245431Sdim Zero = ConstantInt::get(IntTy, 0); 597245431Sdim} 598245431Sdim 599245431SdimSizeOffsetEvalType ObjectSizeOffsetEvaluator::compute(Value *V) { 600245431Sdim SizeOffsetEvalType Result = compute_(V); 601245431Sdim 602245431Sdim if (!bothKnown(Result)) { 603245431Sdim // erase everything that was computed in this iteration from the cache, so 604245431Sdim // that no dangling references are left behind. We could be a bit smarter if 605245431Sdim // we kept a dependency graph. It's probably not worth the complexity. 606245431Sdim for (PtrSetTy::iterator I=SeenVals.begin(), E=SeenVals.end(); I != E; ++I) { 607245431Sdim CacheMapTy::iterator CacheIt = CacheMap.find(*I); 608245431Sdim // non-computable results can be safely cached 609245431Sdim if (CacheIt != CacheMap.end() && anyKnown(CacheIt->second)) 610245431Sdim CacheMap.erase(CacheIt); 611245431Sdim } 612245431Sdim } 613245431Sdim 614245431Sdim SeenVals.clear(); 615245431Sdim return Result; 616245431Sdim} 617245431Sdim 618245431SdimSizeOffsetEvalType ObjectSizeOffsetEvaluator::compute_(Value *V) { 619263509Sdim ObjectSizeOffsetVisitor Visitor(DL, TLI, Context, RoundToAlign); 620245431Sdim SizeOffsetType Const = Visitor.compute(V); 621245431Sdim if (Visitor.bothKnown(Const)) 622245431Sdim return std::make_pair(ConstantInt::get(Context, Const.first), 623245431Sdim ConstantInt::get(Context, Const.second)); 624245431Sdim 625245431Sdim V = V->stripPointerCasts(); 626245431Sdim 627245431Sdim // check cache 628245431Sdim CacheMapTy::iterator CacheIt = CacheMap.find(V); 629245431Sdim if (CacheIt != CacheMap.end()) 630245431Sdim return CacheIt->second; 631245431Sdim 632245431Sdim // always generate code immediately before the instruction being 633245431Sdim // processed, so that the generated code dominates the same BBs 634245431Sdim Instruction *PrevInsertPoint = Builder.GetInsertPoint(); 635245431Sdim if (Instruction *I = dyn_cast<Instruction>(V)) 636245431Sdim Builder.SetInsertPoint(I); 637245431Sdim 638245431Sdim // now compute the size and offset 639245431Sdim SizeOffsetEvalType Result; 640263509Sdim 641263509Sdim // Record the pointers that were handled in this run, so that they can be 642263509Sdim // cleaned later if something fails. We also use this set to break cycles that 643263509Sdim // can occur in dead code. 644263509Sdim if (!SeenVals.insert(V)) { 645263509Sdim Result = unknown(); 646263509Sdim } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { 647245431Sdim Result = visitGEPOperator(*GEP); 648245431Sdim } else if (Instruction *I = dyn_cast<Instruction>(V)) { 649245431Sdim Result = visit(*I); 650245431Sdim } else if (isa<Argument>(V) || 651245431Sdim (isa<ConstantExpr>(V) && 652245431Sdim cast<ConstantExpr>(V)->getOpcode() == Instruction::IntToPtr) || 653252723Sdim isa<GlobalAlias>(V) || 654245431Sdim isa<GlobalVariable>(V)) { 655245431Sdim // ignore values where we cannot do more than what ObjectSizeVisitor can 656245431Sdim Result = unknown(); 657245431Sdim } else { 658245431Sdim DEBUG(dbgs() << "ObjectSizeOffsetEvaluator::compute() unhandled value: " 659245431Sdim << *V << '\n'); 660245431Sdim Result = unknown(); 661245431Sdim } 662245431Sdim 663245431Sdim if (PrevInsertPoint) 664245431Sdim Builder.SetInsertPoint(PrevInsertPoint); 665245431Sdim 666245431Sdim // Don't reuse CacheIt since it may be invalid at this point. 667245431Sdim CacheMap[V] = Result; 668245431Sdim return Result; 669245431Sdim} 670245431Sdim 671245431SdimSizeOffsetEvalType ObjectSizeOffsetEvaluator::visitAllocaInst(AllocaInst &I) { 672245431Sdim if (!I.getAllocatedType()->isSized()) 673245431Sdim return unknown(); 674245431Sdim 675245431Sdim // must be a VLA 676245431Sdim assert(I.isArrayAllocation()); 677245431Sdim Value *ArraySize = I.getArraySize(); 678245431Sdim Value *Size = ConstantInt::get(ArraySize->getType(), 679263509Sdim DL->getTypeAllocSize(I.getAllocatedType())); 680245431Sdim Size = Builder.CreateMul(Size, ArraySize); 681245431Sdim return std::make_pair(Size, Zero); 682245431Sdim} 683245431Sdim 684245431SdimSizeOffsetEvalType ObjectSizeOffsetEvaluator::visitCallSite(CallSite CS) { 685245431Sdim const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc, 686245431Sdim TLI); 687245431Sdim if (!FnData) 688245431Sdim return unknown(); 689245431Sdim 690245431Sdim // handle strdup-like functions separately 691245431Sdim if (FnData->AllocTy == StrDupLike) { 692245431Sdim // TODO 693245431Sdim return unknown(); 694245431Sdim } 695245431Sdim 696245431Sdim Value *FirstArg = CS.getArgument(FnData->FstParam); 697245431Sdim FirstArg = Builder.CreateZExt(FirstArg, IntTy); 698245431Sdim if (FnData->SndParam < 0) 699245431Sdim return std::make_pair(FirstArg, Zero); 700245431Sdim 701245431Sdim Value *SecondArg = CS.getArgument(FnData->SndParam); 702245431Sdim SecondArg = Builder.CreateZExt(SecondArg, IntTy); 703245431Sdim Value *Size = Builder.CreateMul(FirstArg, SecondArg); 704245431Sdim return std::make_pair(Size, Zero); 705245431Sdim 706245431Sdim // TODO: handle more standard functions (+ wchar cousins): 707245431Sdim // - strdup / strndup 708245431Sdim // - strcpy / strncpy 709245431Sdim // - strcat / strncat 710245431Sdim // - memcpy / memmove 711245431Sdim // - strcat / strncat 712245431Sdim // - memset 713245431Sdim} 714245431Sdim 715245431SdimSizeOffsetEvalType 716245431SdimObjectSizeOffsetEvaluator::visitExtractElementInst(ExtractElementInst&) { 717245431Sdim return unknown(); 718245431Sdim} 719245431Sdim 720245431SdimSizeOffsetEvalType 721245431SdimObjectSizeOffsetEvaluator::visitExtractValueInst(ExtractValueInst&) { 722245431Sdim return unknown(); 723245431Sdim} 724245431Sdim 725245431SdimSizeOffsetEvalType 726245431SdimObjectSizeOffsetEvaluator::visitGEPOperator(GEPOperator &GEP) { 727245431Sdim SizeOffsetEvalType PtrData = compute_(GEP.getPointerOperand()); 728245431Sdim if (!bothKnown(PtrData)) 729245431Sdim return unknown(); 730245431Sdim 731263509Sdim Value *Offset = EmitGEPOffset(&Builder, *DL, &GEP, /*NoAssumptions=*/true); 732245431Sdim Offset = Builder.CreateAdd(PtrData.second, Offset); 733245431Sdim return std::make_pair(PtrData.first, Offset); 734245431Sdim} 735245431Sdim 736245431SdimSizeOffsetEvalType ObjectSizeOffsetEvaluator::visitIntToPtrInst(IntToPtrInst&) { 737245431Sdim // clueless 738245431Sdim return unknown(); 739245431Sdim} 740245431Sdim 741245431SdimSizeOffsetEvalType ObjectSizeOffsetEvaluator::visitLoadInst(LoadInst&) { 742245431Sdim return unknown(); 743245431Sdim} 744245431Sdim 745245431SdimSizeOffsetEvalType ObjectSizeOffsetEvaluator::visitPHINode(PHINode &PHI) { 746245431Sdim // create 2 PHIs: one for size and another for offset 747245431Sdim PHINode *SizePHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues()); 748245431Sdim PHINode *OffsetPHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues()); 749245431Sdim 750245431Sdim // insert right away in the cache to handle recursive PHIs 751245431Sdim CacheMap[&PHI] = std::make_pair(SizePHI, OffsetPHI); 752245431Sdim 753245431Sdim // compute offset/size for each PHI incoming pointer 754245431Sdim for (unsigned i = 0, e = PHI.getNumIncomingValues(); i != e; ++i) { 755245431Sdim Builder.SetInsertPoint(PHI.getIncomingBlock(i)->getFirstInsertionPt()); 756245431Sdim SizeOffsetEvalType EdgeData = compute_(PHI.getIncomingValue(i)); 757245431Sdim 758245431Sdim if (!bothKnown(EdgeData)) { 759245431Sdim OffsetPHI->replaceAllUsesWith(UndefValue::get(IntTy)); 760245431Sdim OffsetPHI->eraseFromParent(); 761245431Sdim SizePHI->replaceAllUsesWith(UndefValue::get(IntTy)); 762245431Sdim SizePHI->eraseFromParent(); 763245431Sdim return unknown(); 764245431Sdim } 765245431Sdim SizePHI->addIncoming(EdgeData.first, PHI.getIncomingBlock(i)); 766245431Sdim OffsetPHI->addIncoming(EdgeData.second, PHI.getIncomingBlock(i)); 767245431Sdim } 768245431Sdim 769245431Sdim Value *Size = SizePHI, *Offset = OffsetPHI, *Tmp; 770245431Sdim if ((Tmp = SizePHI->hasConstantValue())) { 771245431Sdim Size = Tmp; 772245431Sdim SizePHI->replaceAllUsesWith(Size); 773245431Sdim SizePHI->eraseFromParent(); 774245431Sdim } 775245431Sdim if ((Tmp = OffsetPHI->hasConstantValue())) { 776245431Sdim Offset = Tmp; 777245431Sdim OffsetPHI->replaceAllUsesWith(Offset); 778245431Sdim OffsetPHI->eraseFromParent(); 779245431Sdim } 780245431Sdim return std::make_pair(Size, Offset); 781245431Sdim} 782245431Sdim 783245431SdimSizeOffsetEvalType ObjectSizeOffsetEvaluator::visitSelectInst(SelectInst &I) { 784245431Sdim SizeOffsetEvalType TrueSide = compute_(I.getTrueValue()); 785245431Sdim SizeOffsetEvalType FalseSide = compute_(I.getFalseValue()); 786245431Sdim 787245431Sdim if (!bothKnown(TrueSide) || !bothKnown(FalseSide)) 788245431Sdim return unknown(); 789245431Sdim if (TrueSide == FalseSide) 790245431Sdim return TrueSide; 791245431Sdim 792245431Sdim Value *Size = Builder.CreateSelect(I.getCondition(), TrueSide.first, 793245431Sdim FalseSide.first); 794245431Sdim Value *Offset = Builder.CreateSelect(I.getCondition(), TrueSide.second, 795245431Sdim FalseSide.second); 796245431Sdim return std::make_pair(Size, Offset); 797245431Sdim} 798245431Sdim 799245431SdimSizeOffsetEvalType ObjectSizeOffsetEvaluator::visitInstruction(Instruction &I) { 800245431Sdim DEBUG(dbgs() << "ObjectSizeOffsetEvaluator unknown instruction:" << I <<'\n'); 801245431Sdim return unknown(); 802245431Sdim} 803