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//===------ MemoryBuiltins.cpp - Identify calls to memory builtins --------===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// This family of functions identifies calls to builtin functions that allocate
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/MemoryBuiltins.h"
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#include "llvm/Constants.h"
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#include "llvm/Instructions.h"
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#include "llvm/Module.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/Target/TargetData.h"
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//===----------------------------------------------------------------------===//
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// malloc Call Utility Functions.
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/// isMalloc - Returns true if the value is either a malloc call or a
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/// bitcast of the result of a malloc call.
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bool llvm::isMalloc(const Value *I) {
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return extractMallocCall(I) || extractMallocCallFromBitCast(I);
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static bool isMallocCall(const CallInst *CI) {
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Function *Callee = CI->getCalledFunction();
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if (Callee == 0 || !Callee->isDeclaration() || Callee->getName() != "malloc")
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// Check malloc prototype.
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// FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
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// attribute will exist.
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const FunctionType *FTy = Callee->getFunctionType();
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if (FTy->getNumParams() != 1)
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if (IntegerType *ITy = dyn_cast<IntegerType>(FTy->param_begin()->get())) {
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if (ITy->getBitWidth() != 32 && ITy->getBitWidth() != 64)
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/// extractMallocCall - Returns the corresponding CallInst if the instruction
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/// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
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/// ignore InvokeInst here.
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const CallInst *llvm::extractMallocCall(const Value *I) {
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const CallInst *CI = dyn_cast<CallInst>(I);
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return (isMallocCall(CI)) ? CI : NULL;
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CallInst *llvm::extractMallocCall(Value *I) {
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CallInst *CI = dyn_cast<CallInst>(I);
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return (isMallocCall(CI)) ? CI : NULL;
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static bool isBitCastOfMallocCall(const BitCastInst *BCI) {
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return isMallocCall(dyn_cast<CallInst>(BCI->getOperand(0)));
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/// extractMallocCallFromBitCast - Returns the corresponding CallInst if the
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/// instruction is a bitcast of the result of a malloc call.
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CallInst *llvm::extractMallocCallFromBitCast(Value *I) {
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BitCastInst *BCI = dyn_cast<BitCastInst>(I);
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return (isBitCastOfMallocCall(BCI)) ? cast<CallInst>(BCI->getOperand(0))
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const CallInst *llvm::extractMallocCallFromBitCast(const Value *I) {
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const BitCastInst *BCI = dyn_cast<BitCastInst>(I);
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return (isBitCastOfMallocCall(BCI)) ? cast<CallInst>(BCI->getOperand(0))
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static Value *computeArraySize(const CallInst *CI, const TargetData *TD,
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bool LookThroughSExt = false) {
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// The size of the malloc's result type must be known to determine array size.
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const Type *T = getMallocAllocatedType(CI);
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if (!T || !T->isSized() || !TD)
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unsigned ElementSize = TD->getTypeAllocSize(T);
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if (const StructType *ST = dyn_cast<StructType>(T))
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ElementSize = TD->getStructLayout(ST)->getSizeInBytes();
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// If malloc calls' arg can be determined to be a multiple of ElementSize,
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// return the multiple. Otherwise, return NULL.
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Value *MallocArg = CI->getOperand(1);
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Value *Multiple = NULL;
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if (ComputeMultiple(MallocArg, ElementSize, Multiple,
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/// isArrayMalloc - Returns the corresponding CallInst if the instruction
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/// is a call to malloc whose array size can be determined and the array size
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/// is not constant 1. Otherwise, return NULL.
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const CallInst *llvm::isArrayMalloc(const Value *I, const TargetData *TD) {
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const CallInst *CI = extractMallocCall(I);
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Value *ArraySize = computeArraySize(CI, TD);
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ArraySize != ConstantInt::get(CI->getOperand(1)->getType(), 1))
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// CI is a non-array malloc or we can't figure out that it is an array malloc.
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/// getMallocType - Returns the PointerType resulting from the malloc call.
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/// The PointerType depends on the number of bitcast uses of the malloc call:
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/// 0: PointerType is the calls' return type.
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/// 1: PointerType is the bitcast's result type.
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/// >1: Unique PointerType cannot be determined, return NULL.
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const PointerType *llvm::getMallocType(const CallInst *CI) {
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assert(isMalloc(CI) && "getMallocType and not malloc call");
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const PointerType *MallocType = NULL;
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unsigned NumOfBitCastUses = 0;
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// Determine if CallInst has a bitcast use.
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for (Value::use_const_iterator UI = CI->use_begin(), E = CI->use_end();
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if (const BitCastInst *BCI = dyn_cast<BitCastInst>(*UI++)) {
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MallocType = cast<PointerType>(BCI->getDestTy());
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// Malloc call has 1 bitcast use, so type is the bitcast's destination type.
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if (NumOfBitCastUses == 1)
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// Malloc call was not bitcast, so type is the malloc function's return type.
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if (NumOfBitCastUses == 0)
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return cast<PointerType>(CI->getType());
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// Type could not be determined.
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/// getMallocAllocatedType - Returns the Type allocated by malloc call.
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/// The Type depends on the number of bitcast uses of the malloc call:
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/// 0: PointerType is the malloc calls' return type.
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/// 1: PointerType is the bitcast's result type.
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/// >1: Unique PointerType cannot be determined, return NULL.
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const Type *llvm::getMallocAllocatedType(const CallInst *CI) {
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const PointerType *PT = getMallocType(CI);
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return PT ? PT->getElementType() : NULL;
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/// getMallocArraySize - Returns the array size of a malloc call. If the
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/// argument passed to malloc is a multiple of the size of the malloced type,
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/// then return that multiple. For non-array mallocs, the multiple is
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/// constant 1. Otherwise, return NULL for mallocs whose array size cannot be
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Value *llvm::getMallocArraySize(CallInst *CI, const TargetData *TD,
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bool LookThroughSExt) {
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assert(isMalloc(CI) && "getMallocArraySize and not malloc call");
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return computeArraySize(CI, TD, LookThroughSExt);
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//===----------------------------------------------------------------------===//
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// free Call Utility Functions.
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/// isFreeCall - Returns true if the value is a call to the builtin free()
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bool llvm::isFreeCall(const Value *I) {
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const CallInst *CI = dyn_cast<CallInst>(I);
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Function *Callee = CI->getCalledFunction();
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if (Callee == 0 || !Callee->isDeclaration() || Callee->getName() != "free")
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// Check free prototype.
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// FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
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// attribute will exist.
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const FunctionType *FTy = Callee->getFunctionType();
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if (!FTy->getReturnType()->isVoidTy())
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if (FTy->getNumParams() != 1)
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if (FTy->param_begin()->get() != Type::getInt8PtrTy(Callee->getContext()))