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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.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Target/TargetData.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);
}
static bool isMallocCall(const CallInst *CI) {
if (!CI)
return false;
Function *Callee = CI->getCalledFunction();
if (Callee == 0 || !Callee->isDeclaration() || Callee->getName() != "malloc")
return false;
// Check malloc prototype.
// FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
// attribute will exist.
const FunctionType *FTy = Callee->getFunctionType();
if (FTy->getNumParams() != 1)
return false;
if (IntegerType *ITy = dyn_cast<IntegerType>(FTy->param_begin()->get())) {
if (ITy->getBitWidth() != 32 && ITy->getBitWidth() != 64)
return false;
return true;
}
return false;
}
/// 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<CallInst>(I);
return (isMallocCall(CI)) ? CI : NULL;
}
CallInst *llvm::extractMallocCall(Value *I) {
CallInst *CI = dyn_cast<CallInst>(I);
return (isMallocCall(CI)) ? CI : NULL;
}
static bool isBitCastOfMallocCall(const BitCastInst *BCI) {
if (!BCI)
return false;
return isMallocCall(dyn_cast<CallInst>(BCI->getOperand(0)));
}
/// 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<BitCastInst>(I);
return (isBitCastOfMallocCall(BCI)) ? cast<CallInst>(BCI->getOperand(0))
: NULL;
}
const CallInst *llvm::extractMallocCallFromBitCast(const Value *I) {
const BitCastInst *BCI = dyn_cast<BitCastInst>(I);
return (isBitCastOfMallocCall(BCI)) ? cast<CallInst>(BCI->getOperand(0))
: NULL;
}
static Value *computeArraySize(const CallInst *CI, const TargetData *TD,
bool LookThroughSExt = false) {
if (!CI)
return NULL;
// The size of the malloc's result type must be known to determine array size.
const Type *T = getMallocAllocatedType(CI);
if (!T || !T->isSized() || !TD)
return NULL;
unsigned ElementSize = TD->getTypeAllocSize(T);
if (const 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 CallInst *CI = extractMallocCall(I);
Value *ArraySize = computeArraySize(CI, TD);
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.
const PointerType *llvm::getMallocType(const CallInst *CI) {
assert(isMalloc(CI) && "getMallocType and not malloc call");
const 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.
const Type *llvm::getMallocAllocatedType(const CallInst *CI) {
const PointerType *PT = getMallocType(CI);
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,
bool LookThroughSExt) {
assert(isMalloc(CI) && "getMallocArraySize and not malloc call");
return computeArraySize(CI, TD, LookThroughSExt);
}
//===----------------------------------------------------------------------===//
// 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 *CI = dyn_cast<CallInst>(I);
if (!CI)
return 0;
Function *Callee = CI->getCalledFunction();
if (Callee == 0 || !Callee->isDeclaration() || Callee->getName() != "free")
return 0;
// Check free prototype.
// FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
// attribute will exist.
const FunctionType *FTy = Callee->getFunctionType();
if (!FTy->getReturnType()->isVoidTy())
return 0;
if (FTy->getNumParams() != 1)
return 0;
if (FTy->param_begin()->get() != Type::getInt8PtrTy(Callee->getContext()))
return 0;
return CI;
}
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