llvm-mirror/lib/Analysis/MemoryBuiltins.cpp

283 lines
9.6 KiB
C++

//===------ 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/ConstantFolding.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
// malloc Call Utility Functions.
//
/// isMalloc - Returns true if the 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;
const Module *M = CI->getParent()->getParent()->getParent();
Function *MallocFunc = M->getFunction("malloc");
if (CI->getOperand(0) != MallocFunc)
return false;
// Check malloc prototype.
// FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
// attribute will exist.
const FunctionType *FTy = MallocFunc->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;
}
/// isConstantOne - Return true only if val is constant int 1.
static bool isConstantOne(Value *val) {
return isa<ConstantInt>(val) && cast<ConstantInt>(val)->isOne();
}
static Value *isArrayMallocHelper(const CallInst *CI, LLVMContext &Context,
const TargetData *TD) {
if (!CI)
return NULL;
// Type must be known to determine array size.
const Type *T = getMallocAllocatedType(CI);
if (!T)
return NULL;
Value *MallocArg = CI->getOperand(1);
ConstantExpr *CO = dyn_cast<ConstantExpr>(MallocArg);
BinaryOperator *BO = dyn_cast<BinaryOperator>(MallocArg);
Constant *ElementSize = ConstantExpr::getSizeOf(T);
ElementSize = ConstantExpr::getTruncOrBitCast(ElementSize,
MallocArg->getType());
Constant *FoldedElementSize =
ConstantFoldConstantExpression(cast<ConstantExpr>(ElementSize), Context, TD);
// First, check if CI is a non-array malloc.
if (CO && ((CO == ElementSize) ||
(FoldedElementSize && (CO == FoldedElementSize))))
// Match CreateMalloc's use of constant 1 array-size for non-array mallocs.
return ConstantInt::get(MallocArg->getType(), 1);
// Second, check if CI is an array malloc whose array size can be determined.
if (isConstantOne(ElementSize) ||
(FoldedElementSize && isConstantOne(FoldedElementSize)))
return MallocArg;
if (!CO && !BO)
return NULL;
Value *Op0 = NULL;
Value *Op1 = NULL;
unsigned Opcode = 0;
if (CO && ((CO->getOpcode() == Instruction::Mul) ||
(CO->getOpcode() == Instruction::Shl))) {
Op0 = CO->getOperand(0);
Op1 = CO->getOperand(1);
Opcode = CO->getOpcode();
}
if (BO && ((BO->getOpcode() == Instruction::Mul) ||
(BO->getOpcode() == Instruction::Shl))) {
Op0 = BO->getOperand(0);
Op1 = BO->getOperand(1);
Opcode = BO->getOpcode();
}
// Determine array size if malloc's argument is the product of a mul or shl.
if (Op0) {
if (Opcode == Instruction::Mul) {
if ((Op1 == ElementSize) ||
(FoldedElementSize && (Op1 == FoldedElementSize)))
// ArraySize * ElementSize
return Op0;
if ((Op0 == ElementSize) ||
(FoldedElementSize && (Op0 == FoldedElementSize)))
// ElementSize * ArraySize
return Op1;
}
if (Opcode == Instruction::Shl) {
ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1);
if (!Op1CI) return NULL;
APInt Op1Int = Op1CI->getValue();
uint64_t BitToSet = Op1Int.getLimitedValue(Op1Int.getBitWidth() - 1);
Value *Op1Pow = ConstantInt::get(Context,
APInt(Op1Int.getBitWidth(), 0).set(BitToSet));
if (Op0 == ElementSize || (FoldedElementSize && Op0 == FoldedElementSize))
// ArraySize << log2(ElementSize)
return Op1Pow;
if (Op1Pow == ElementSize ||
(FoldedElementSize && Op1Pow == FoldedElementSize))
// ElementSize << log2(ArraySize)
return Op0;
}
}
// We could not determine the malloc array size from MallocArg.
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.
CallInst *llvm::isArrayMalloc(Value *I, LLVMContext &Context,
const TargetData *TD) {
CallInst *CI = extractMallocCall(I);
Value *ArraySize = isArrayMallocHelper(CI, Context, TD);
if (ArraySize &&
ArraySize != ConstantInt::get(CI->getOperand(1)->getType(), 1))
return CI;
// CI is a non-array malloc or we can't figure out that it is an array malloc.
return NULL;
}
const CallInst *llvm::isArrayMalloc(const Value *I, LLVMContext &Context,
const TargetData *TD) {
const CallInst *CI = extractMallocCall(I);
Value *ArraySize = isArrayMallocHelper(CI, Context, TD);
if (ArraySize &&
ArraySize != ConstantInt::get(CI->getOperand(1)->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.
/// This PointerType is the result type of the call's only bitcast use.
/// If there is no unique bitcast use, then return NULL.
const PointerType *llvm::getMallocType(const CallInst *CI) {
assert(isMalloc(CI) && "GetMallocType and not malloc call");
const BitCastInst *BCI = NULL;
// Determine if CallInst has a bitcast use.
for (Value::use_const_iterator UI = CI->use_begin(), E = CI->use_end();
UI != E; )
if ((BCI = dyn_cast<BitCastInst>(cast<Instruction>(*UI++))))
break;
// Malloc call has 1 bitcast use and no other uses, so type is the bitcast's
// destination type.
if (BCI && CI->hasOneUse())
return cast<PointerType>(BCI->getDestTy());
// Malloc call was not bitcast, so type is the malloc function's return type.
if (!BCI)
return cast<PointerType>(CI->getType());
// Type could not be determined.
return NULL;
}
/// getMallocAllocatedType - Returns the Type allocated by malloc call. This
/// Type is the result type of the call's only bitcast use. If there is no
/// unique bitcast use, then 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, LLVMContext &Context,
const TargetData *TD) {
return isArrayMallocHelper(CI, Context, TD);
}
//===----------------------------------------------------------------------===//
// free Call Utility Functions.
//
/// isFreeCall - Returns true if the the value is a call to the builtin free()
bool llvm::isFreeCall(const Value *I) {
const CallInst *CI = dyn_cast<CallInst>(I);
if (!CI)
return false;
const Module *M = CI->getParent()->getParent()->getParent();
Function *FreeFunc = M->getFunction("free");
if (CI->getOperand(0) != FreeFunc)
return false;
// Check free prototype.
// FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
// attribute will exist.
const FunctionType *FTy = FreeFunc->getFunctionType();
if (FTy->getReturnType() != Type::getVoidTy(M->getContext()))
return false;
if (FTy->getNumParams() != 1)
return false;
if (FTy->param_begin()->get() != Type::getInt8PtrTy(M->getContext()))
return false;
return true;
}