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Diffstat (limited to 'lib/Analysis/MemoryBuiltins.cpp')
| -rw-r--r-- | lib/Analysis/MemoryBuiltins.cpp | 770 |
1 files changed, 770 insertions, 0 deletions
diff --git a/lib/Analysis/MemoryBuiltins.cpp b/lib/Analysis/MemoryBuiltins.cpp new file mode 100644 index 00000000000..5b2313e3a6e --- /dev/null +++ b/lib/Analysis/MemoryBuiltins.cpp @@ -0,0 +1,770 @@ +//===------ 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/ADT/Statistic.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/Analysis/MemoryBuiltins.h" +#include "llvm/GlobalVariable.h" +#include "llvm/Instructions.h" +#include "llvm/Intrinsics.h" +#include "llvm/Metadata.h" +#include "llvm/Module.h" +#include "llvm/Analysis/ValueTracking.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/MathExtras.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Target/TargetData.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 TargetData *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 TargetData *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 TargetData *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 TargetData *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 TargetData *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 TargetData *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(); +} |