| //===------ MemoryBuiltins.cpp - Identify calls to memory builtins --------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This family of functions identifies calls to builtin functions that allocate |
| // or free memory. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "memory-builtins" |
| #include "llvm/Analysis/MemoryBuiltins.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/ADT/Statistic.h" |
| #include "llvm/Analysis/ValueTracking.h" |
| #include "llvm/DataLayout.h" |
| #include "llvm/GlobalVariable.h" |
| #include "llvm/Instructions.h" |
| #include "llvm/Intrinsics.h" |
| #include "llvm/Metadata.h" |
| #include "llvm/Module.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/MathExtras.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include "llvm/Target/TargetLibraryInfo.h" |
| #include "llvm/Transforms/Utils/Local.h" |
| using namespace llvm; |
| |
| enum AllocType { |
| MallocLike = 1<<0, // allocates |
| CallocLike = 1<<1, // allocates + bzero |
| ReallocLike = 1<<2, // reallocates |
| StrDupLike = 1<<3, |
| AllocLike = MallocLike | CallocLike | StrDupLike, |
| AnyAlloc = MallocLike | CallocLike | ReallocLike | StrDupLike |
| }; |
| |
| struct AllocFnsTy { |
| LibFunc::Func Func; |
| AllocType AllocTy; |
| unsigned char NumParams; |
| // First and Second size parameters (or -1 if unused) |
| signed char FstParam, SndParam; |
| }; |
| |
| // FIXME: certain users need more information. E.g., SimplifyLibCalls needs to |
| // know which functions are nounwind, noalias, nocapture parameters, etc. |
| static const AllocFnsTy AllocationFnData[] = { |
| {LibFunc::malloc, MallocLike, 1, 0, -1}, |
| {LibFunc::valloc, MallocLike, 1, 0, -1}, |
| {LibFunc::Znwj, MallocLike, 1, 0, -1}, // new(unsigned int) |
| {LibFunc::ZnwjRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new(unsigned int, nothrow) |
| {LibFunc::Znwm, MallocLike, 1, 0, -1}, // new(unsigned long) |
| {LibFunc::ZnwmRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new(unsigned long, nothrow) |
| {LibFunc::Znaj, MallocLike, 1, 0, -1}, // new[](unsigned int) |
| {LibFunc::ZnajRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new[](unsigned int, nothrow) |
| {LibFunc::Znam, MallocLike, 1, 0, -1}, // new[](unsigned long) |
| {LibFunc::ZnamRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new[](unsigned long, nothrow) |
| {LibFunc::posix_memalign, MallocLike, 3, 2, -1}, |
| {LibFunc::calloc, CallocLike, 2, 0, 1}, |
| {LibFunc::realloc, ReallocLike, 2, 1, -1}, |
| {LibFunc::reallocf, ReallocLike, 2, 1, -1}, |
| {LibFunc::strdup, StrDupLike, 1, -1, -1}, |
| {LibFunc::strndup, StrDupLike, 2, 1, -1} |
| }; |
| |
| |
| static Function *getCalledFunction(const Value *V, bool LookThroughBitCast) { |
| if (LookThroughBitCast) |
| V = V->stripPointerCasts(); |
| |
| CallSite CS(const_cast<Value*>(V)); |
| if (!CS.getInstruction()) |
| return 0; |
| |
| Function *Callee = CS.getCalledFunction(); |
| if (!Callee || !Callee->isDeclaration()) |
| return 0; |
| return Callee; |
| } |
| |
| /// \brief Returns the allocation data for the given value if it is a call to a |
| /// known allocation function, and NULL otherwise. |
| static const AllocFnsTy *getAllocationData(const Value *V, AllocType AllocTy, |
| const TargetLibraryInfo *TLI, |
| bool LookThroughBitCast = false) { |
| Function *Callee = getCalledFunction(V, LookThroughBitCast); |
| if (!Callee) |
| return 0; |
| |
| // Make sure that the function is available. |
| StringRef FnName = Callee->getName(); |
| LibFunc::Func TLIFn; |
| if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn)) |
| return 0; |
| |
| unsigned i = 0; |
| bool found = false; |
| for ( ; i < array_lengthof(AllocationFnData); ++i) { |
| if (AllocationFnData[i].Func == TLIFn) { |
| found = true; |
| break; |
| } |
| } |
| if (!found) |
| return 0; |
| |
| const AllocFnsTy *FnData = &AllocationFnData[i]; |
| if ((FnData->AllocTy & AllocTy) == 0) |
| return 0; |
| |
| // Check function prototype. |
| int FstParam = FnData->FstParam; |
| int SndParam = FnData->SndParam; |
| FunctionType *FTy = Callee->getFunctionType(); |
| |
| if (FTy->getReturnType() == Type::getInt8PtrTy(FTy->getContext()) && |
| FTy->getNumParams() == FnData->NumParams && |
| (FstParam < 0 || |
| (FTy->getParamType(FstParam)->isIntegerTy(32) || |
| FTy->getParamType(FstParam)->isIntegerTy(64))) && |
| (SndParam < 0 || |
| FTy->getParamType(SndParam)->isIntegerTy(32) || |
| FTy->getParamType(SndParam)->isIntegerTy(64))) |
| return FnData; |
| return 0; |
| } |
| |
| static bool hasNoAliasAttr(const Value *V, bool LookThroughBitCast) { |
| ImmutableCallSite CS(LookThroughBitCast ? V->stripPointerCasts() : V); |
| return CS && CS.hasFnAttr(Attribute::NoAlias); |
| } |
| |
| |
| /// \brief Tests if a value is a call or invoke to a library function that |
| /// allocates or reallocates memory (either malloc, calloc, realloc, or strdup |
| /// like). |
| bool llvm::isAllocationFn(const Value *V, const TargetLibraryInfo *TLI, |
| bool LookThroughBitCast) { |
| return getAllocationData(V, AnyAlloc, TLI, LookThroughBitCast); |
| } |
| |
| /// \brief Tests if a value is a call or invoke to a function that returns a |
| /// NoAlias pointer (including malloc/calloc/realloc/strdup-like functions). |
| bool llvm::isNoAliasFn(const Value *V, const TargetLibraryInfo *TLI, |
| bool LookThroughBitCast) { |
| // it's safe to consider realloc as noalias since accessing the original |
| // pointer is undefined behavior |
| return isAllocationFn(V, TLI, LookThroughBitCast) || |
| hasNoAliasAttr(V, LookThroughBitCast); |
| } |
| |
| /// \brief Tests if a value is a call or invoke to a library function that |
| /// allocates uninitialized memory (such as malloc). |
| bool llvm::isMallocLikeFn(const Value *V, const TargetLibraryInfo *TLI, |
| bool LookThroughBitCast) { |
| return getAllocationData(V, MallocLike, TLI, LookThroughBitCast); |
| } |
| |
| /// \brief Tests if a value is a call or invoke to a library function that |
| /// allocates zero-filled memory (such as calloc). |
| bool llvm::isCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI, |
| bool LookThroughBitCast) { |
| return getAllocationData(V, CallocLike, TLI, LookThroughBitCast); |
| } |
| |
| /// \brief Tests if a value is a call or invoke to a library function that |
| /// allocates memory (either malloc, calloc, or strdup like). |
| bool llvm::isAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI, |
| bool LookThroughBitCast) { |
| return getAllocationData(V, AllocLike, TLI, LookThroughBitCast); |
| } |
| |
| /// \brief Tests if a value is a call or invoke to a library function that |
| /// reallocates memory (such as realloc). |
| bool llvm::isReallocLikeFn(const Value *V, const TargetLibraryInfo *TLI, |
| bool LookThroughBitCast) { |
| return getAllocationData(V, ReallocLike, TLI, LookThroughBitCast); |
| } |
| |
| /// extractMallocCall - Returns the corresponding CallInst if the instruction |
| /// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we |
| /// ignore InvokeInst here. |
| const CallInst *llvm::extractMallocCall(const Value *I, |
| const TargetLibraryInfo *TLI) { |
| return isMallocLikeFn(I, TLI) ? dyn_cast<CallInst>(I) : 0; |
| } |
| |
| static Value *computeArraySize(const CallInst *CI, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| bool LookThroughSExt = false) { |
| if (!CI) |
| return NULL; |
| |
| // The size of the malloc's result type must be known to determine array size. |
| Type *T = getMallocAllocatedType(CI, TLI); |
| if (!T || !T->isSized() || !TD) |
| return NULL; |
| |
| unsigned ElementSize = TD->getTypeAllocSize(T); |
| if (StructType *ST = dyn_cast<StructType>(T)) |
| ElementSize = TD->getStructLayout(ST)->getSizeInBytes(); |
| |
| // If malloc call's arg can be determined to be a multiple of ElementSize, |
| // return the multiple. Otherwise, return NULL. |
| Value *MallocArg = CI->getArgOperand(0); |
| Value *Multiple = NULL; |
| if (ComputeMultiple(MallocArg, ElementSize, Multiple, |
| LookThroughSExt)) |
| return Multiple; |
| |
| return NULL; |
| } |
| |
| /// isArrayMalloc - Returns the corresponding CallInst if the instruction |
| /// is a call to malloc whose array size can be determined and the array size |
| /// is not constant 1. Otherwise, return NULL. |
| const CallInst *llvm::isArrayMalloc(const Value *I, |
| const DataLayout *TD, |
| const TargetLibraryInfo *TLI) { |
| const CallInst *CI = extractMallocCall(I, TLI); |
| Value *ArraySize = computeArraySize(CI, TD, TLI); |
| |
| if (ArraySize && |
| ArraySize != ConstantInt::get(CI->getArgOperand(0)->getType(), 1)) |
| return CI; |
| |
| // CI is a non-array malloc or we can't figure out that it is an array malloc. |
| return NULL; |
| } |
| |
| /// getMallocType - Returns the PointerType resulting from the malloc call. |
| /// The PointerType depends on the number of bitcast uses of the malloc call: |
| /// 0: PointerType is the calls' return type. |
| /// 1: PointerType is the bitcast's result type. |
| /// >1: Unique PointerType cannot be determined, return NULL. |
| PointerType *llvm::getMallocType(const CallInst *CI, |
| const TargetLibraryInfo *TLI) { |
| assert(isMallocLikeFn(CI, TLI) && "getMallocType and not malloc call"); |
| |
| PointerType *MallocType = NULL; |
| unsigned NumOfBitCastUses = 0; |
| |
| // Determine if CallInst has a bitcast use. |
| for (Value::const_use_iterator UI = CI->use_begin(), E = CI->use_end(); |
| UI != E; ) |
| if (const BitCastInst *BCI = dyn_cast<BitCastInst>(*UI++)) { |
| MallocType = cast<PointerType>(BCI->getDestTy()); |
| NumOfBitCastUses++; |
| } |
| |
| // Malloc call has 1 bitcast use, so type is the bitcast's destination type. |
| if (NumOfBitCastUses == 1) |
| return MallocType; |
| |
| // Malloc call was not bitcast, so type is the malloc function's return type. |
| if (NumOfBitCastUses == 0) |
| return cast<PointerType>(CI->getType()); |
| |
| // Type could not be determined. |
| return NULL; |
| } |
| |
| /// getMallocAllocatedType - Returns the Type allocated by malloc call. |
| /// The Type depends on the number of bitcast uses of the malloc call: |
| /// 0: PointerType is the malloc calls' return type. |
| /// 1: PointerType is the bitcast's result type. |
| /// >1: Unique PointerType cannot be determined, return NULL. |
| Type *llvm::getMallocAllocatedType(const CallInst *CI, |
| const TargetLibraryInfo *TLI) { |
| PointerType *PT = getMallocType(CI, TLI); |
| return PT ? PT->getElementType() : NULL; |
| } |
| |
| /// getMallocArraySize - Returns the array size of a malloc call. If the |
| /// argument passed to malloc is a multiple of the size of the malloced type, |
| /// then return that multiple. For non-array mallocs, the multiple is |
| /// constant 1. Otherwise, return NULL for mallocs whose array size cannot be |
| /// determined. |
| Value *llvm::getMallocArraySize(CallInst *CI, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| bool LookThroughSExt) { |
| assert(isMallocLikeFn(CI, TLI) && "getMallocArraySize and not malloc call"); |
| return computeArraySize(CI, TD, TLI, LookThroughSExt); |
| } |
| |
| |
| /// extractCallocCall - Returns the corresponding CallInst if the instruction |
| /// is a calloc call. |
| const CallInst *llvm::extractCallocCall(const Value *I, |
| const TargetLibraryInfo *TLI) { |
| return isCallocLikeFn(I, TLI) ? cast<CallInst>(I) : 0; |
| } |
| |
| |
| /// isFreeCall - Returns non-null if the value is a call to the builtin free() |
| const CallInst *llvm::isFreeCall(const Value *I, const TargetLibraryInfo *TLI) { |
| const CallInst *CI = dyn_cast<CallInst>(I); |
| if (!CI) |
| return 0; |
| Function *Callee = CI->getCalledFunction(); |
| if (Callee == 0 || !Callee->isDeclaration()) |
| return 0; |
| |
| StringRef FnName = Callee->getName(); |
| LibFunc::Func TLIFn; |
| if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn)) |
| return 0; |
| |
| if (TLIFn != LibFunc::free && |
| TLIFn != LibFunc::ZdlPv && // operator delete(void*) |
| TLIFn != LibFunc::ZdaPv) // operator delete[](void*) |
| return 0; |
| |
| // Check free prototype. |
| // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin |
| // attribute will exist. |
| FunctionType *FTy = Callee->getFunctionType(); |
| if (!FTy->getReturnType()->isVoidTy()) |
| return 0; |
| if (FTy->getNumParams() != 1) |
| return 0; |
| if (FTy->getParamType(0) != Type::getInt8PtrTy(Callee->getContext())) |
| return 0; |
| |
| return CI; |
| } |
| |
| |
| |
| //===----------------------------------------------------------------------===// |
| // Utility functions to compute size of objects. |
| // |
| |
| |
| /// \brief Compute the size of the object pointed by Ptr. Returns true and the |
| /// object size in Size if successful, and false otherwise. |
| /// If RoundToAlign is true, then Size is rounded up to the aligment of allocas, |
| /// byval arguments, and global variables. |
| bool llvm::getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout *TD, |
| const TargetLibraryInfo *TLI, bool RoundToAlign) { |
| if (!TD) |
| return false; |
| |
| ObjectSizeOffsetVisitor Visitor(TD, TLI, Ptr->getContext(), RoundToAlign); |
| SizeOffsetType Data = Visitor.compute(const_cast<Value*>(Ptr)); |
| if (!Visitor.bothKnown(Data)) |
| return false; |
| |
| APInt ObjSize = Data.first, Offset = Data.second; |
| // check for overflow |
| if (Offset.slt(0) || ObjSize.ult(Offset)) |
| Size = 0; |
| else |
| Size = (ObjSize - Offset).getZExtValue(); |
| return true; |
| } |
| |
| |
| STATISTIC(ObjectVisitorArgument, |
| "Number of arguments with unsolved size and offset"); |
| STATISTIC(ObjectVisitorLoad, |
| "Number of load instructions with unsolved size and offset"); |
| |
| |
| APInt ObjectSizeOffsetVisitor::align(APInt Size, uint64_t Align) { |
| if (RoundToAlign && Align) |
| return APInt(IntTyBits, RoundUpToAlignment(Size.getZExtValue(), Align)); |
| return Size; |
| } |
| |
| ObjectSizeOffsetVisitor::ObjectSizeOffsetVisitor(const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| LLVMContext &Context, |
| bool RoundToAlign) |
| : TD(TD), TLI(TLI), RoundToAlign(RoundToAlign) { |
| IntegerType *IntTy = TD->getIntPtrType(Context); |
| IntTyBits = IntTy->getBitWidth(); |
| Zero = APInt::getNullValue(IntTyBits); |
| } |
| |
| SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) { |
| V = V->stripPointerCasts(); |
| if (Instruction *I = dyn_cast<Instruction>(V)) { |
| // If we have already seen this instruction, bail out. Cycles can happen in |
| // unreachable code after constant propagation. |
| if (!SeenInsts.insert(I)) |
| return unknown(); |
| |
| if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) |
| return visitGEPOperator(*GEP); |
| return visit(*I); |
| } |
| if (Argument *A = dyn_cast<Argument>(V)) |
| return visitArgument(*A); |
| if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V)) |
| return visitConstantPointerNull(*P); |
| if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) |
| return visitGlobalVariable(*GV); |
| if (UndefValue *UV = dyn_cast<UndefValue>(V)) |
| return visitUndefValue(*UV); |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { |
| if (CE->getOpcode() == Instruction::IntToPtr) |
| return unknown(); // clueless |
| if (CE->getOpcode() == Instruction::GetElementPtr) |
| return visitGEPOperator(cast<GEPOperator>(*CE)); |
| } |
| |
| DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: " << *V |
| << '\n'); |
| return unknown(); |
| } |
| |
| SizeOffsetType ObjectSizeOffsetVisitor::visitAllocaInst(AllocaInst &I) { |
| if (!I.getAllocatedType()->isSized()) |
| return unknown(); |
| |
| APInt Size(IntTyBits, TD->getTypeAllocSize(I.getAllocatedType())); |
| if (!I.isArrayAllocation()) |
| return std::make_pair(align(Size, I.getAlignment()), Zero); |
| |
| Value *ArraySize = I.getArraySize(); |
| if (const ConstantInt *C = dyn_cast<ConstantInt>(ArraySize)) { |
| Size *= C->getValue().zextOrSelf(IntTyBits); |
| return std::make_pair(align(Size, I.getAlignment()), Zero); |
| } |
| return unknown(); |
| } |
| |
| SizeOffsetType ObjectSizeOffsetVisitor::visitArgument(Argument &A) { |
| // no interprocedural analysis is done at the moment |
| if (!A.hasByValAttr()) { |
| ++ObjectVisitorArgument; |
| return unknown(); |
| } |
| PointerType *PT = cast<PointerType>(A.getType()); |
| APInt Size(IntTyBits, TD->getTypeAllocSize(PT->getElementType())); |
| return std::make_pair(align(Size, A.getParamAlignment()), Zero); |
| } |
| |
| SizeOffsetType ObjectSizeOffsetVisitor::visitCallSite(CallSite CS) { |
| const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc, |
| TLI); |
| if (!FnData) |
| return unknown(); |
| |
| // handle strdup-like functions separately |
| if (FnData->AllocTy == StrDupLike) { |
| APInt Size(IntTyBits, GetStringLength(CS.getArgument(0))); |
| if (!Size) |
| return unknown(); |
| |
| // strndup limits strlen |
| if (FnData->FstParam > 0) { |
| ConstantInt *Arg= dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam)); |
| if (!Arg) |
| return unknown(); |
| |
| APInt MaxSize = Arg->getValue().zextOrSelf(IntTyBits); |
| if (Size.ugt(MaxSize)) |
| Size = MaxSize + 1; |
| } |
| return std::make_pair(Size, Zero); |
| } |
| |
| ConstantInt *Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam)); |
| if (!Arg) |
| return unknown(); |
| |
| APInt Size = Arg->getValue().zextOrSelf(IntTyBits); |
| // size determined by just 1 parameter |
| if (FnData->SndParam < 0) |
| return std::make_pair(Size, Zero); |
| |
| Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->SndParam)); |
| if (!Arg) |
| return unknown(); |
| |
| Size *= Arg->getValue().zextOrSelf(IntTyBits); |
| return std::make_pair(Size, Zero); |
| |
| // TODO: handle more standard functions (+ wchar cousins): |
| // - strdup / strndup |
| // - strcpy / strncpy |
| // - strcat / strncat |
| // - memcpy / memmove |
| // - strcat / strncat |
| // - memset |
| } |
| |
| SizeOffsetType |
| ObjectSizeOffsetVisitor::visitConstantPointerNull(ConstantPointerNull&) { |
| return std::make_pair(Zero, Zero); |
| } |
| |
| SizeOffsetType |
| ObjectSizeOffsetVisitor::visitExtractElementInst(ExtractElementInst&) { |
| return unknown(); |
| } |
| |
| SizeOffsetType |
| ObjectSizeOffsetVisitor::visitExtractValueInst(ExtractValueInst&) { |
| // Easy cases were already folded by previous passes. |
| return unknown(); |
| } |
| |
| SizeOffsetType ObjectSizeOffsetVisitor::visitGEPOperator(GEPOperator &GEP) { |
| SizeOffsetType PtrData = compute(GEP.getPointerOperand()); |
| if (!bothKnown(PtrData) || !GEP.hasAllConstantIndices()) |
| return unknown(); |
| |
| SmallVector<Value*, 8> Ops(GEP.idx_begin(), GEP.idx_end()); |
| APInt Offset(IntTyBits,TD->getIndexedOffset(GEP.getPointerOperandType(),Ops)); |
| return std::make_pair(PtrData.first, PtrData.second + Offset); |
| } |
| |
| SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalVariable(GlobalVariable &GV){ |
| if (!GV.hasDefinitiveInitializer()) |
| return unknown(); |
| |
| APInt Size(IntTyBits, TD->getTypeAllocSize(GV.getType()->getElementType())); |
| return std::make_pair(align(Size, GV.getAlignment()), Zero); |
| } |
| |
| SizeOffsetType ObjectSizeOffsetVisitor::visitIntToPtrInst(IntToPtrInst&) { |
| // clueless |
| return unknown(); |
| } |
| |
| SizeOffsetType ObjectSizeOffsetVisitor::visitLoadInst(LoadInst&) { |
| ++ObjectVisitorLoad; |
| return unknown(); |
| } |
| |
| SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode&) { |
| // too complex to analyze statically. |
| return unknown(); |
| } |
| |
| SizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) { |
| SizeOffsetType TrueSide = compute(I.getTrueValue()); |
| SizeOffsetType FalseSide = compute(I.getFalseValue()); |
| if (bothKnown(TrueSide) && bothKnown(FalseSide) && TrueSide == FalseSide) |
| return TrueSide; |
| return unknown(); |
| } |
| |
| SizeOffsetType ObjectSizeOffsetVisitor::visitUndefValue(UndefValue&) { |
| return std::make_pair(Zero, Zero); |
| } |
| |
| SizeOffsetType ObjectSizeOffsetVisitor::visitInstruction(Instruction &I) { |
| DEBUG(dbgs() << "ObjectSizeOffsetVisitor unknown instruction:" << I << '\n'); |
| return unknown(); |
| } |
| |
| |
| ObjectSizeOffsetEvaluator::ObjectSizeOffsetEvaluator(const DataLayout *TD, |
| const TargetLibraryInfo *TLI, |
| LLVMContext &Context) |
| : TD(TD), TLI(TLI), Context(Context), Builder(Context, TargetFolder(TD)) { |
| IntTy = TD->getIntPtrType(Context); |
| Zero = ConstantInt::get(IntTy, 0); |
| } |
| |
| SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute(Value *V) { |
| SizeOffsetEvalType Result = compute_(V); |
| |
| if (!bothKnown(Result)) { |
| // erase everything that was computed in this iteration from the cache, so |
| // that no dangling references are left behind. We could be a bit smarter if |
| // we kept a dependency graph. It's probably not worth the complexity. |
| for (PtrSetTy::iterator I=SeenVals.begin(), E=SeenVals.end(); I != E; ++I) { |
| CacheMapTy::iterator CacheIt = CacheMap.find(*I); |
| // non-computable results can be safely cached |
| if (CacheIt != CacheMap.end() && anyKnown(CacheIt->second)) |
| CacheMap.erase(CacheIt); |
| } |
| } |
| |
| SeenVals.clear(); |
| return Result; |
| } |
| |
| SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute_(Value *V) { |
| ObjectSizeOffsetVisitor Visitor(TD, TLI, Context); |
| SizeOffsetType Const = Visitor.compute(V); |
| if (Visitor.bothKnown(Const)) |
| return std::make_pair(ConstantInt::get(Context, Const.first), |
| ConstantInt::get(Context, Const.second)); |
| |
| V = V->stripPointerCasts(); |
| |
| // check cache |
| CacheMapTy::iterator CacheIt = CacheMap.find(V); |
| if (CacheIt != CacheMap.end()) |
| return CacheIt->second; |
| |
| // always generate code immediately before the instruction being |
| // processed, so that the generated code dominates the same BBs |
| Instruction *PrevInsertPoint = Builder.GetInsertPoint(); |
| if (Instruction *I = dyn_cast<Instruction>(V)) |
| Builder.SetInsertPoint(I); |
| |
| // record the pointers that were handled in this run, so that they can be |
| // cleaned later if something fails |
| SeenVals.insert(V); |
| |
| // now compute the size and offset |
| SizeOffsetEvalType Result; |
| if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) { |
| Result = visitGEPOperator(*GEP); |
| } else if (Instruction *I = dyn_cast<Instruction>(V)) { |
| Result = visit(*I); |
| } else if (isa<Argument>(V) || |
| (isa<ConstantExpr>(V) && |
| cast<ConstantExpr>(V)->getOpcode() == Instruction::IntToPtr) || |
| isa<GlobalVariable>(V)) { |
| // ignore values where we cannot do more than what ObjectSizeVisitor can |
| Result = unknown(); |
| } else { |
| DEBUG(dbgs() << "ObjectSizeOffsetEvaluator::compute() unhandled value: " |
| << *V << '\n'); |
| Result = unknown(); |
| } |
| |
| if (PrevInsertPoint) |
| Builder.SetInsertPoint(PrevInsertPoint); |
| |
| // Don't reuse CacheIt since it may be invalid at this point. |
| CacheMap[V] = Result; |
| return Result; |
| } |
| |
| SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitAllocaInst(AllocaInst &I) { |
| if (!I.getAllocatedType()->isSized()) |
| return unknown(); |
| |
| // must be a VLA |
| assert(I.isArrayAllocation()); |
| Value *ArraySize = I.getArraySize(); |
| Value *Size = ConstantInt::get(ArraySize->getType(), |
| TD->getTypeAllocSize(I.getAllocatedType())); |
| Size = Builder.CreateMul(Size, ArraySize); |
| return std::make_pair(Size, Zero); |
| } |
| |
| SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitCallSite(CallSite CS) { |
| const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc, |
| TLI); |
| if (!FnData) |
| return unknown(); |
| |
| // handle strdup-like functions separately |
| if (FnData->AllocTy == StrDupLike) { |
| // TODO |
| return unknown(); |
| } |
| |
| Value *FirstArg = CS.getArgument(FnData->FstParam); |
| FirstArg = Builder.CreateZExt(FirstArg, IntTy); |
| if (FnData->SndParam < 0) |
| return std::make_pair(FirstArg, Zero); |
| |
| Value *SecondArg = CS.getArgument(FnData->SndParam); |
| SecondArg = Builder.CreateZExt(SecondArg, IntTy); |
| Value *Size = Builder.CreateMul(FirstArg, SecondArg); |
| return std::make_pair(Size, Zero); |
| |
| // TODO: handle more standard functions (+ wchar cousins): |
| // - strdup / strndup |
| // - strcpy / strncpy |
| // - strcat / strncat |
| // - memcpy / memmove |
| // - strcat / strncat |
| // - memset |
| } |
| |
| SizeOffsetEvalType |
| ObjectSizeOffsetEvaluator::visitExtractElementInst(ExtractElementInst&) { |
| return unknown(); |
| } |
| |
| SizeOffsetEvalType |
| ObjectSizeOffsetEvaluator::visitExtractValueInst(ExtractValueInst&) { |
| return unknown(); |
| } |
| |
| SizeOffsetEvalType |
| ObjectSizeOffsetEvaluator::visitGEPOperator(GEPOperator &GEP) { |
| SizeOffsetEvalType PtrData = compute_(GEP.getPointerOperand()); |
| if (!bothKnown(PtrData)) |
| return unknown(); |
| |
| Value *Offset = EmitGEPOffset(&Builder, *TD, &GEP, /*NoAssumptions=*/true); |
| Offset = Builder.CreateAdd(PtrData.second, Offset); |
| return std::make_pair(PtrData.first, Offset); |
| } |
| |
| SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitIntToPtrInst(IntToPtrInst&) { |
| // clueless |
| return unknown(); |
| } |
| |
| SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitLoadInst(LoadInst&) { |
| return unknown(); |
| } |
| |
| SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitPHINode(PHINode &PHI) { |
| // create 2 PHIs: one for size and another for offset |
| PHINode *SizePHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues()); |
| PHINode *OffsetPHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues()); |
| |
| // insert right away in the cache to handle recursive PHIs |
| CacheMap[&PHI] = std::make_pair(SizePHI, OffsetPHI); |
| |
| // compute offset/size for each PHI incoming pointer |
| for (unsigned i = 0, e = PHI.getNumIncomingValues(); i != e; ++i) { |
| Builder.SetInsertPoint(PHI.getIncomingBlock(i)->getFirstInsertionPt()); |
| SizeOffsetEvalType EdgeData = compute_(PHI.getIncomingValue(i)); |
| |
| if (!bothKnown(EdgeData)) { |
| OffsetPHI->replaceAllUsesWith(UndefValue::get(IntTy)); |
| OffsetPHI->eraseFromParent(); |
| SizePHI->replaceAllUsesWith(UndefValue::get(IntTy)); |
| SizePHI->eraseFromParent(); |
| return unknown(); |
| } |
| SizePHI->addIncoming(EdgeData.first, PHI.getIncomingBlock(i)); |
| OffsetPHI->addIncoming(EdgeData.second, PHI.getIncomingBlock(i)); |
| } |
| |
| Value *Size = SizePHI, *Offset = OffsetPHI, *Tmp; |
| if ((Tmp = SizePHI->hasConstantValue())) { |
| Size = Tmp; |
| SizePHI->replaceAllUsesWith(Size); |
| SizePHI->eraseFromParent(); |
| } |
| if ((Tmp = OffsetPHI->hasConstantValue())) { |
| Offset = Tmp; |
| OffsetPHI->replaceAllUsesWith(Offset); |
| OffsetPHI->eraseFromParent(); |
| } |
| return std::make_pair(Size, Offset); |
| } |
| |
| SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitSelectInst(SelectInst &I) { |
| SizeOffsetEvalType TrueSide = compute_(I.getTrueValue()); |
| SizeOffsetEvalType FalseSide = compute_(I.getFalseValue()); |
| |
| if (!bothKnown(TrueSide) || !bothKnown(FalseSide)) |
| return unknown(); |
| if (TrueSide == FalseSide) |
| return TrueSide; |
| |
| Value *Size = Builder.CreateSelect(I.getCondition(), TrueSide.first, |
| FalseSide.first); |
| Value *Offset = Builder.CreateSelect(I.getCondition(), TrueSide.second, |
| FalseSide.second); |
| return std::make_pair(Size, Offset); |
| } |
| |
| SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitInstruction(Instruction &I) { |
| DEBUG(dbgs() << "ObjectSizeOffsetEvaluator unknown instruction:" << I <<'\n'); |
| return unknown(); |
| } |