X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FMemoryBuiltins.cpp;h=64d339f564d75766862761a50941e5a1099c8d2b;hb=12af22e8cc217827cf4f118b0f5e4ebbda9925ae;hp=347a7ea7a8b9cc17cf18ff76f8084ed8b0882512;hpb=252ef566e8734b6bcf46434d0a7954c9eda0bd96;p=oota-llvm.git diff --git a/lib/Analysis/MemoryBuiltins.cpp b/lib/Analysis/MemoryBuiltins.cpp index 347a7ea7a8b..64d339f564d 100644 --- a/lib/Analysis/MemoryBuiltins.cpp +++ b/lib/Analysis/MemoryBuiltins.cpp @@ -8,124 +8,245 @@ //===----------------------------------------------------------------------===// // // This family of functions identifies calls to builtin functions that allocate -// or free memory. +// or free memory. // //===----------------------------------------------------------------------===// #include "llvm/Analysis/MemoryBuiltins.h" -#include "llvm/Constants.h" -#include "llvm/Instructions.h" -#include "llvm/Module.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/Statistic.h" #include "llvm/Analysis/ValueTracking.h" -#include "llvm/Target/TargetData.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/GlobalVariable.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/Intrinsics.h" +#include "llvm/IR/Metadata.h" +#include "llvm/IR/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; -//===----------------------------------------------------------------------===// -// malloc Call Utility Functions. -// - -/// isMalloc - Returns true if the value is either a malloc call or a -/// bitcast of the result of a malloc call. -bool llvm::isMalloc(const Value *I) { - return extractMallocCall(I) || extractMallocCallFromBitCast(I); +#define DEBUG_TYPE "memory-builtins" + +enum AllocType { + OpNewLike = 1<<0, // allocates; never returns null + MallocLike = 1<<1 | OpNewLike, // allocates; may return null + CallocLike = 1<<2, // allocates + bzero + ReallocLike = 1<<3, // reallocates + StrDupLike = 1<<4, + AllocLike = MallocLike | CallocLike | StrDupLike, + AnyAlloc = AllocLike | ReallocLike +}; + +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, OpNewLike, 1, 0, -1}, // new(unsigned int) + {LibFunc::ZnwjRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new(unsigned int, nothrow) + {LibFunc::Znwm, OpNewLike, 1, 0, -1}, // new(unsigned long) + {LibFunc::ZnwmRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new(unsigned long, nothrow) + {LibFunc::Znaj, OpNewLike, 1, 0, -1}, // new[](unsigned int) + {LibFunc::ZnajRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new[](unsigned int, nothrow) + {LibFunc::Znam, OpNewLike, 1, 0, -1}, // new[](unsigned long) + {LibFunc::ZnamRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new[](unsigned long, nothrow) + {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} + // TODO: Handle "int posix_memalign(void **, size_t, size_t)" +}; + + +static Function *getCalledFunction(const Value *V, bool LookThroughBitCast) { + if (LookThroughBitCast) + V = V->stripPointerCasts(); + + CallSite CS(const_cast(V)); + if (!CS.getInstruction()) + return nullptr; + + if (CS.isNoBuiltin()) + return nullptr; + + Function *Callee = CS.getCalledFunction(); + if (!Callee || !Callee->isDeclaration()) + return nullptr; + return Callee; } -static bool isMallocCall(const CallInst *CI) { - if (!CI) - return false; +/// \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) { + // Skip intrinsics + if (isa(V)) + return nullptr; + + Function *Callee = getCalledFunction(V, LookThroughBitCast); + if (!Callee) + return nullptr; + + // Make sure that the function is available. + StringRef FnName = Callee->getName(); + LibFunc::Func TLIFn; + if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn)) + return nullptr; + + unsigned i = 0; + bool found = false; + for ( ; i < array_lengthof(AllocationFnData); ++i) { + if (AllocationFnData[i].Func == TLIFn) { + found = true; + break; + } + } + if (!found) + return nullptr; - Function *Callee = CI->getCalledFunction(); - if (Callee == 0 || !Callee->isDeclaration()) - return false; - if (Callee->getName() != "malloc" && - Callee->getName() != "_Znwj" && // operator new(unsigned int) - Callee->getName() != "_Znwm" && // operator new(unsigned long) - Callee->getName() != "_Znaj" && // operator new[](unsigned int) - Callee->getName() != "_Znam") // operator new[](unsigned long) - return false; + const AllocFnsTy *FnData = &AllocationFnData[i]; + if ((FnData->AllocTy & AllocTy) != FnData->AllocTy) + return nullptr; - // Check malloc prototype. - // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin - // attribute will exist. + // Check function prototype. + int FstParam = FnData->FstParam; + int SndParam = FnData->SndParam; FunctionType *FTy = Callee->getFunctionType(); - return FTy->getReturnType() == Type::getInt8PtrTy(FTy->getContext()) && - FTy->getNumParams() == 1 && - (FTy->getParamType(0)->isIntegerTy(32) || - FTy->getParamType(0)->isIntegerTy(64)); + + 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 nullptr; } -/// 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 CallInst *CI = dyn_cast(I); - return (isMallocCall(CI)) ? CI : NULL; +static bool hasNoAliasAttr(const Value *V, bool LookThroughBitCast) { + ImmutableCallSite CS(LookThroughBitCast ? V->stripPointerCasts() : V); + return CS && CS.hasFnAttr(Attribute::NoAlias); } -CallInst *llvm::extractMallocCall(Value *I) { - CallInst *CI = dyn_cast(I); - return (isMallocCall(CI)) ? CI : NULL; + +/// \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); } -static bool isBitCastOfMallocCall(const BitCastInst *BCI) { - if (!BCI) - return false; - - return isMallocCall(dyn_cast(BCI->getOperand(0))); +/// \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); } -/// extractMallocCallFromBitCast - Returns the corresponding CallInst if the -/// instruction is a bitcast of the result of a malloc call. -CallInst *llvm::extractMallocCallFromBitCast(Value *I) { - BitCastInst *BCI = dyn_cast(I); - return (isBitCastOfMallocCall(BCI)) ? cast(BCI->getOperand(0)) - : NULL; +/// \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); } -const CallInst *llvm::extractMallocCallFromBitCast(const Value *I) { - const BitCastInst *BCI = dyn_cast(I); - return (isBitCastOfMallocCall(BCI)) ? cast(BCI->getOperand(0)) - : NULL; +/// \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); } -static Value *computeArraySize(const CallInst *CI, const TargetData *TD, +/// \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); +} + +/// \brief Tests if a value is a call or invoke to a library function that +/// allocates memory and never returns null (such as operator new). +bool llvm::isOperatorNewLikeFn(const Value *V, const TargetLibraryInfo *TLI, + bool LookThroughBitCast) { + return getAllocationData(V, OpNewLike, 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(I) : nullptr; +} + +static Value *computeArraySize(const CallInst *CI, const DataLayout *DL, + const TargetLibraryInfo *TLI, bool LookThroughSExt = false) { if (!CI) - return NULL; + return nullptr; // The size of the malloc's result type must be known to determine array size. - Type *T = getMallocAllocatedType(CI); - if (!T || !T->isSized() || !TD) - return NULL; + Type *T = getMallocAllocatedType(CI, TLI); + if (!T || !T->isSized() || !DL) + return nullptr; - unsigned ElementSize = TD->getTypeAllocSize(T); + unsigned ElementSize = DL->getTypeAllocSize(T); if (StructType *ST = dyn_cast(T)) - ElementSize = TD->getStructLayout(ST)->getSizeInBytes(); + ElementSize = DL->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; + Value *Multiple = nullptr; if (ComputeMultiple(MallocArg, ElementSize, Multiple, LookThroughSExt)) return Multiple; - return NULL; + return nullptr; } -/// isArrayMalloc - Returns the corresponding CallInst if the instruction +/// 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 CallInst *CI = extractMallocCall(I); - Value *ArraySize = computeArraySize(CI, TD); +const CallInst *llvm::isArrayMalloc(const Value *I, + const DataLayout *DL, + const TargetLibraryInfo *TLI) { + const CallInst *CI = extractMallocCall(I, TLI); + Value *ArraySize = computeArraySize(CI, DL, TLI); - if (ArraySize && - ArraySize != ConstantInt::get(CI->getArgOperand(0)->getType(), 1)) - return CI; + if (ConstantInt *ConstSize = dyn_cast_or_null(ArraySize)) + if (ConstSize->isOne()) + return CI; // CI is a non-array malloc or we can't figure out that it is an array malloc. - return NULL; + return nullptr; } /// getMallocType - Returns the PointerType resulting from the malloc call. @@ -133,15 +254,16 @@ const CallInst *llvm::isArrayMalloc(const Value *I, const TargetData *TD) { /// 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) { - assert(isMalloc(CI) && "getMallocType and not malloc call"); - - PointerType *MallocType = NULL; +PointerType *llvm::getMallocType(const CallInst *CI, + const TargetLibraryInfo *TLI) { + assert(isMallocLikeFn(CI, TLI) && "getMallocType and not malloc call"); + + PointerType *MallocType = nullptr; 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; ) + for (Value::const_user_iterator UI = CI->user_begin(), E = CI->user_end(); + UI != E;) if (const BitCastInst *BCI = dyn_cast(*UI++)) { MallocType = cast(BCI->getDestTy()); NumOfBitCastUses++; @@ -156,7 +278,7 @@ PointerType *llvm::getMallocType(const CallInst *CI) { return cast(CI->getType()); // Type could not be determined. - return NULL; + return nullptr; } /// getMallocAllocatedType - Returns the Type allocated by malloc call. @@ -164,90 +286,524 @@ PointerType *llvm::getMallocType(const CallInst *CI) { /// 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) { - PointerType *PT = getMallocType(CI); - return PT ? PT->getElementType() : NULL; +Type *llvm::getMallocAllocatedType(const CallInst *CI, + const TargetLibraryInfo *TLI) { + PointerType *PT = getMallocType(CI, TLI); + return PT ? PT->getElementType() : nullptr; } -/// getMallocArraySize - Returns the array size of a malloc call. If the +/// 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, +Value *llvm::getMallocArraySize(CallInst *CI, const DataLayout *DL, + const TargetLibraryInfo *TLI, bool LookThroughSExt) { - assert(isMalloc(CI) && "getMallocArraySize and not malloc call"); - return computeArraySize(CI, TD, LookThroughSExt); + assert(isMallocLikeFn(CI, TLI) && "getMallocArraySize and not malloc call"); + return computeArraySize(CI, DL, TLI, LookThroughSExt); } -//===----------------------------------------------------------------------===// -// clloc Call Utility Functions. -// - -static bool isCallocCall(const CallInst *CI) { - if (!CI) - return false; - - Function *Callee = CI->getCalledFunction(); - if (Callee == 0 || !Callee->isDeclaration()) - return false; - if (Callee->getName() != "calloc") - return false; - - // Check malloc prototype. - // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin - // attribute will exist. - FunctionType *FTy = Callee->getFunctionType(); - return FTy->getReturnType() == Type::getInt8PtrTy(FTy->getContext()) && - FTy->getNumParams() == 2 && - ((FTy->getParamType(0)->isIntegerTy(32) && - FTy->getParamType(1)->isIntegerTy(32)) || - (FTy->getParamType(0)->isIntegerTy(64) && - FTy->getParamType(1)->isIntegerTy(64))); -} - /// extractCallocCall - Returns the corresponding CallInst if the instruction /// is a calloc call. -const CallInst *llvm::extractCallocCall(const Value *I) { - const CallInst *CI = dyn_cast(I); - return isCallocCall(CI) ? CI : 0; -} - -CallInst *llvm::extractCallocCall(Value *I) { - CallInst *CI = dyn_cast(I); - return isCallocCall(CI) ? CI : 0; +const CallInst *llvm::extractCallocCall(const Value *I, + const TargetLibraryInfo *TLI) { + return isCallocLikeFn(I, TLI) ? cast(I) : nullptr; } -//===----------------------------------------------------------------------===// -// free Call Utility Functions. -// - /// isFreeCall - Returns non-null if the value is a call to the builtin free() -const CallInst *llvm::isFreeCall(const Value *I) { +const CallInst *llvm::isFreeCall(const Value *I, const TargetLibraryInfo *TLI) { const CallInst *CI = dyn_cast(I); - if (!CI) - return 0; + if (!CI || isa(CI)) + return nullptr; Function *Callee = CI->getCalledFunction(); - if (Callee == 0 || !Callee->isDeclaration()) - return 0; - - if (Callee->getName() != "free" && - Callee->getName() != "_ZdlPv" && // operator delete(void*) - Callee->getName() != "_ZdaPv") // operator delete[](void*) - return 0; + if (Callee == nullptr || !Callee->isDeclaration()) + return nullptr; + + StringRef FnName = Callee->getName(); + LibFunc::Func TLIFn; + if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn)) + return nullptr; + + unsigned ExpectedNumParams; + if (TLIFn == LibFunc::free || + TLIFn == LibFunc::ZdlPv || // operator delete(void*) + TLIFn == LibFunc::ZdaPv) // operator delete[](void*) + ExpectedNumParams = 1; + else if (TLIFn == LibFunc::ZdlPvRKSt9nothrow_t || // delete(void*, nothrow) + TLIFn == LibFunc::ZdaPvRKSt9nothrow_t) // delete[](void*, nothrow) + ExpectedNumParams = 2; + else + return nullptr; // Check free prototype. - // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin + // 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; + return nullptr; + if (FTy->getNumParams() != ExpectedNumParams) + return nullptr; if (FTy->getParamType(0) != Type::getInt8PtrTy(Callee->getContext())) - return 0; + return nullptr; 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 *DL, + const TargetLibraryInfo *TLI, bool RoundToAlign) { + if (!DL) + return false; + + ObjectSizeOffsetVisitor Visitor(DL, TLI, Ptr->getContext(), RoundToAlign); + SizeOffsetType Data = Visitor.compute(const_cast(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 *DL, + const TargetLibraryInfo *TLI, + LLVMContext &Context, + bool RoundToAlign) +: DL(DL), TLI(TLI), RoundToAlign(RoundToAlign) { + // Pointer size must be rechecked for each object visited since it could have + // a different address space. +} + +SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) { + IntTyBits = DL->getPointerTypeSizeInBits(V->getType()); + Zero = APInt::getNullValue(IntTyBits); + + V = V->stripPointerCasts(); + if (Instruction *I = dyn_cast(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(V)) + return visitGEPOperator(*GEP); + return visit(*I); + } + if (Argument *A = dyn_cast(V)) + return visitArgument(*A); + if (ConstantPointerNull *P = dyn_cast(V)) + return visitConstantPointerNull(*P); + if (GlobalAlias *GA = dyn_cast(V)) + return visitGlobalAlias(*GA); + if (GlobalVariable *GV = dyn_cast(V)) + return visitGlobalVariable(*GV); + if (UndefValue *UV = dyn_cast(V)) + return visitUndefValue(*UV); + if (ConstantExpr *CE = dyn_cast(V)) { + if (CE->getOpcode() == Instruction::IntToPtr) + return unknown(); // clueless + if (CE->getOpcode() == Instruction::GetElementPtr) + return visitGEPOperator(cast(*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, DL->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(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.hasByValOrInAllocaAttr()) { + ++ObjectVisitorArgument; + return unknown(); + } + PointerType *PT = cast(A.getType()); + APInt Size(IntTyBits, DL->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(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(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(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()); + APInt Offset(IntTyBits, 0); + if (!bothKnown(PtrData) || !GEP.accumulateConstantOffset(*DL, Offset)) + return unknown(); + + return std::make_pair(PtrData.first, PtrData.second + Offset); +} + +SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalAlias(GlobalAlias &GA) { + if (GA.mayBeOverridden()) + return unknown(); + return compute(GA.getAliasee()); +} + +SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalVariable(GlobalVariable &GV){ + if (!GV.hasDefinitiveInitializer()) + return unknown(); + + APInt Size(IntTyBits, DL->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 *DL, + const TargetLibraryInfo *TLI, + LLVMContext &Context, + bool RoundToAlign) +: DL(DL), TLI(TLI), Context(Context), Builder(Context, TargetFolder(DL)), + RoundToAlign(RoundToAlign) { + // IntTy and Zero must be set for each compute() since the address space may + // be different for later objects. +} + +SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute(Value *V) { + // XXX - Are vectors of pointers possible here? + IntTy = cast(DL->getIntPtrType(V->getType())); + Zero = ConstantInt::get(IntTy, 0); + + 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(DL, TLI, Context, RoundToAlign); + 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(V)) + Builder.SetInsertPoint(I); + + // now compute the size and offset + SizeOffsetEvalType Result; + + // Record the pointers that were handled in this run, so that they can be + // cleaned later if something fails. We also use this set to break cycles that + // can occur in dead code. + if (!SeenVals.insert(V)) { + Result = unknown(); + } else if (GEPOperator *GEP = dyn_cast(V)) { + Result = visitGEPOperator(*GEP); + } else if (Instruction *I = dyn_cast(V)) { + Result = visit(*I); + } else if (isa(V) || + (isa(V) && + cast(V)->getOpcode() == Instruction::IntToPtr) || + isa(V) || + isa(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(), + DL->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, *DL, &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(); +}