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8e0d1c03ca
llvm/lib/Analysis/MemoryBuiltins.cpp
Benjamin Kramer 8e0d1c03ca Make MemoryBuiltins aware of TargetLibraryInfo. 
This disables malloc-specific optimization when -fno-builtin (or -ffreestanding)
is specified. This has been a problem for a long time but became more severe
with the recent memory builtin improvements.

Since the memory builtin functions are used everywhere, this required passing
TLI in many places. This means that functions that now have an optional TLI
argument, like RecursivelyDeleteTriviallyDeadFunctions, won't remove dead
mallocs anymore if the TLI argument is missing. I've updated most passes to do
the right thing.

Fixes PR13694 and probably others.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162841 91177308-0d34-0410-b5e6-96231b3b80d8
2012-08-29 15:32:21 +00:00

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//===------ 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();
}
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