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Add malloc call utility functions. Patch by Victor Hernandez. 

llvm-svn: 81426
This commit is contained in:
Evan Cheng 2009-09-10 04:36:43 +00:00
parent 2ffe029a61
commit 1d9d4bdc99
5 changed files with 417 additions and 52 deletions
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86
llvm/include/llvm/Analysis/MallocHelper.h Normal file
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@ -0,0 +1,86 @@
//===- llvm/Analysis/MallocHelper.h ---- Identify malloc calls --*- C++ -*-===//
//
// 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 malloc, bitcasts of malloc
// calls, and the types and array sizes associated with them.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_MALLOCHELPER_H
#define LLVM_ANALYSIS_MALLOCHELPER_H
namespace llvm {
class BitCastInst;
class CallInst;
class Instruction;
class PointerType;
class Twine;
class Type;
class Value;
//===----------------------------------------------------------------------===//
// 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 isMalloc(const Value* I);
bool isMalloc(Value* I);
/// extractMallocCall - Returns the corresponding CallInst if the instruction
/// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
/// ignore InvokeInst here.
const CallInst* extractMallocCall(const Value* I);
CallInst* extractMallocCall(Value* I);
/// extractMallocCallFromBitCast - Returns the corresponding CallInst if the
/// instruction is a bitcast of the result of a malloc call.
const CallInst* extractMallocCallFromBitCast(const Value* I);
CallInst* extractMallocCallFromBitCast(Value* I);
/// isArrayMalloc - Returns the corresponding CallInst if the instruction
/// matches the malloc call IR generated by CallInst::CreateMalloc(). This
/// means that it is a malloc call with one bitcast use AND the malloc call's
/// size argument is:
/// 1. a constant not equal to the malloc's allocated type
/// or
/// 2. the result of a multiplication by the malloc's allocated type
/// Otherwise it returns NULL.
/// The unique bitcast is needed to determine the type/size of the array
/// allocation.
CallInst* isArrayMalloc(Value* I);
const CallInst* isArrayMalloc(const Value* I);
/// 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* getMallocType(const CallInst* CI);
/// 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* getMallocAllocatedType(const CallInst* CI);
/// getMallocArraySize - Returns the array size of a malloc call. The array
/// size is computated in 1 of 3 ways:
/// 1. If the element type if of size 1, then array size is the argument to
/// malloc.
/// 2. Else if the malloc's argument is a constant, the array size is that
/// argument divided by the element type's size.
/// 3. Else the malloc argument must be a multiplication and the array size is
/// the first operand of the multiplication.
/// This function returns constant 1 if:
/// 1. The malloc call's allocated type cannot be determined.
/// 2. IR wasn't created by a call to CallInst::CreateMalloc() with a non-NULL
/// ArraySize.
Value* getMallocArraySize(CallInst* CI);
} // End llvm namespace
#endif

12
llvm/include/llvm/Instructions.h
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@ -1033,6 +1033,18 @@ public:
BasicBlock *InsertAtEnd) {
return new(1) CallInst(F, NameStr, InsertAtEnd);
}
/// CreateMalloc - Generate the IR for a call to malloc:
/// 1. Compute the malloc call's argument as the specified type's size,
/// possibly multiplied by the array size if the array size is not
/// constant 1.
/// 2. Call malloc with that argument.
/// 3. Bitcast the result of the malloc call to the specified type.
static Value *CreateMalloc(Instruction *I,
const Type *AllocTy, const Type *IntPtrTy,
Value *ArraySize = 0, const Twine &NameStr = "");
static Value *CreateMalloc(BasicBlock *InsertAtEnd,
const Type *AllocTy, const Type *IntPtrTy,
Value *ArraySize = 0, const Twine &NameStr = "");
~CallInst();

202
llvm/lib/Analysis/MallocHelper.cpp Normal file
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@ -0,0 +1,202 @@
//===-- MallocHelper.cpp - Functions to identify malloc calls -------------===//
//
// 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 malloc, bitcasts of malloc
// calls, and the types and array sizes associated with them.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/MallocHelper.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/Module.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(Value* I) {
return extractMallocCall(I) || extractMallocCallFromBitCast(I);
}
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();
Constant *MallocFunc = M->getFunction("malloc");
if (CI->getOperand(0) != MallocFunc)
return false;
return true;
}
/// 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 bool isArrayMallocHelper(const CallInst *CI) {
if (!CI)
return false;
// Only identify array mallocs for mallocs with 1 bitcast use. The unique
// bitcast is needed to determine the type/size of the array allocation.
if (!CI->hasOneUse()) return false;
for (Value::use_const_iterator UI = CI->use_begin(), E = CI->use_end();
UI != E; )
if (!isa<BitCastInst>(cast<Instruction>(*UI++)))
return false;
// malloc arg
Value* MallocArg = CI->getOperand(1);
// element size
const Type* T = getMallocAllocatedType(CI);
if (!T) return false;
Constant *ElementSize = ConstantExpr::getSizeOf(T);
if (isa<ConstantExpr>(MallocArg))
return (MallocArg == ElementSize) ? false : true;
BinaryOperator *BI = dyn_cast<BinaryOperator>(MallocArg);
if (!BI)
return false;
if (BI->getOpcode() != Instruction::Mul)
return false;
if (BI->getOperand(1) != ElementSize)
return false;
return true;
}
/// isArrayMalloc - Returns the corresponding CallInst if the instruction
/// matches the malloc call IR generated by CallInst::CreateMalloc(). This
/// means that it is a malloc call with one bitcast use AND the malloc call's
/// size argument is:
/// 1. a constant not equal to the malloc's allocated type
/// or
/// 2. the result of a multiplication by the malloc's allocated type
/// Otherwise it returns NULL.
/// The unique bitcast is needed to determine the type/size of the array
/// allocation.
CallInst* llvm::isArrayMalloc(Value* I) {
CallInst *CI = extractMallocCall(I);
return (isArrayMallocHelper(CI)) ? CI : NULL;
}
const CallInst* llvm::isArrayMalloc(const Value* I) {
const CallInst *CI = extractMallocCall(I);
return (isArrayMallocHelper(CI)) ? CI : 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 type only if there is only 1 bitcast use of CI.
if (CI->hasOneUse())
for (Value::use_const_iterator UI = CI->use_begin(), E = CI->use_end();
UI != E; )
BCI = dyn_cast<BitCastInst>(cast<Instruction>(*UI++));
return BCI ? reinterpret_cast<const PointerType*>(BCI->getDestTy()) : 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;
}
/// isConstantOne - Return true only if val is constant int 1.
static bool isConstantOne(Value *val) {
return isa<ConstantInt>(val) && cast<ConstantInt>(val)->isOne();
}
/// getMallocArraySize - Returns the array size of a malloc call. The array
/// size is computated in 1 of 3 ways:
/// 1. If the element type if of size 1, then array size is the argument to
/// malloc.
/// 2. Else if the malloc's argument is a constant, the array size is that
/// argument divided by the element type's size.
/// 3. Else the malloc argument must be a multiplication and the array size is
/// the first operand of the multiplication.
/// This function returns constant 1 if:
/// 1. The malloc call's allocated type cannot be determined.
/// 2. IR wasn't created by a call to CallInst::CreateMalloc() with a non-NULL
/// ArraySize.
Value* llvm::getMallocArraySize(CallInst* CI) {
// Match CreateMalloc's use of constant 1 array-size for non-array mallocs.
if (!isArrayMalloc(CI))
return ConstantInt::get(CI->getOperand(1)->getType(), 1);
Value* MallocArg = CI->getOperand(1);
assert(getMallocAllocatedType(CI) && "getMallocArraySize and no type");
Constant *ElementSize = ConstantExpr::getSizeOf(getMallocAllocatedType(CI));
ElementSize = ConstantExpr::getTruncOrBitCast(cast<Constant>(ElementSize),
MallocArg->getType());
Constant* CO = dyn_cast<Constant>(MallocArg);
BinaryOperator* BO = dyn_cast<BinaryOperator>(MallocArg);
assert(isConstantOne(ElementSize) || CO || BO &&
"getMallocArraySize and malformed malloc IR");
if (isConstantOne(ElementSize))
return MallocArg;
if (CO)
return ConstantExpr::getUDiv(CO, ElementSize);
assert(BO && "getMallocArraySize not constant but not multiplication either");
return BO->getOperand(0);
}

58
llvm/lib/Transforms/Utils/LowerAllocations.cpp
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@ -33,13 +33,13 @@ namespace {
/// @free calls.
///
class VISIBILITY_HIDDEN LowerAllocations : public BasicBlockPass {
Constant *MallocFunc; // Functions in the module we are processing
Constant *FreeFunc; // Initialized by doInitialization
Constant *FreeFunc; // Functions in the module we are processing
// Initialized by doInitialization
bool LowerMallocArgToInteger;
public:
static char ID; // Pass ID, replacement for typeid
explicit LowerAllocations(bool LowerToInt = false)
: BasicBlockPass(&ID), MallocFunc(0), FreeFunc(0),
: BasicBlockPass(&ID), FreeFunc(0),
LowerMallocArgToInteger(LowerToInt) {}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
@ -88,10 +88,6 @@ Pass *llvm::createLowerAllocationsPass(bool LowerMallocArgToInteger) {
//
bool LowerAllocations::doInitialization(Module &M) {
const Type *BPTy = PointerType::getUnqual(Type::getInt8Ty(M.getContext()));
// Prototype malloc as "char* malloc(...)", because we don't know in
// doInitialization whether size_t is int or long.
FunctionType *FT = FunctionType::get(BPTy, true);
MallocFunc = M.getOrInsertFunction("malloc", FT);
FreeFunc = M.getOrInsertFunction("free" , Type::getVoidTy(M.getContext()),
BPTy, (Type *)0);
return true;
@ -102,7 +98,7 @@ bool LowerAllocations::doInitialization(Module &M) {
//
bool LowerAllocations::runOnBasicBlock(BasicBlock &BB) {
bool Changed = false;
assert(MallocFunc && FreeFunc && "Pass not initialized!");
assert(FreeFunc && "Pass not initialized!");
BasicBlock::InstListType &BBIL = BB.getInstList();
@ -112,50 +108,8 @@ bool LowerAllocations::runOnBasicBlock(BasicBlock &BB) {
// Loop over all of the instructions, looking for malloc or free instructions
for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I) {
if (MallocInst *MI = dyn_cast<MallocInst>(I)) {
const Type *AllocTy = MI->getType()->getElementType();
// malloc(type) becomes i8 *malloc(size)
Value *MallocArg;
if (LowerMallocArgToInteger)
MallocArg = ConstantInt::get(Type::getInt64Ty(BB.getContext()),
TD.getTypeAllocSize(AllocTy));
else
MallocArg = ConstantExpr::getSizeOf(AllocTy);
MallocArg =
ConstantExpr::getTruncOrBitCast(cast<Constant>(MallocArg),
IntPtrTy);
if (MI->isArrayAllocation()) {
if (isa<ConstantInt>(MallocArg) &&
cast<ConstantInt>(MallocArg)->isOne()) {
MallocArg = MI->getOperand(0); // Operand * 1 = Operand
} else if (Constant *CO = dyn_cast<Constant>(MI->getOperand(0))) {
CO =
ConstantExpr::getIntegerCast(CO, IntPtrTy, false /*ZExt*/);
MallocArg = ConstantExpr::getMul(CO,
cast<Constant>(MallocArg));
} else {
Value *Scale = MI->getOperand(0);
if (Scale->getType() != IntPtrTy)
Scale = CastInst::CreateIntegerCast(Scale, IntPtrTy, false /*ZExt*/,
"", I);
// Multiply it by the array size if necessary...
MallocArg = BinaryOperator::Create(Instruction::Mul, Scale,
MallocArg, "", I);
}
}
// Create the call to Malloc.
CallInst *MCall = CallInst::Create(MallocFunc, MallocArg, "", I);
MCall->setTailCall();
// Create a cast instruction to convert to the right type...
Value *MCast;
if (MCall->getType() != Type::getVoidTy(BB.getContext()))
MCast = new BitCastInst(MCall, MI->getType(), "", I);
else
MCast = Constant::getNullValue(MI->getType());
Value *MCast = CallInst::CreateMalloc(I, MI->getType(), IntPtrTy,
MI->getOperand(0));
// Replace all uses of the old malloc inst with the cast inst
MI->replaceAllUsesWith(MCast);

111
llvm/lib/VMCore/Instructions.cpp
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@ -16,6 +16,7 @@
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/Operator.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Support/ErrorHandling.h"
@ -440,6 +441,116 @@ bool CallInst::paramHasAttr(unsigned i, Attributes attr) const {
return false;
}
/// IsConstantOne - Return true only if val is constant int 1
static bool IsConstantOne(Value *val) {
assert(val && "IsConstantOne does not work with NULL val");
return isa<ConstantInt>(val) && cast<ConstantInt>(val)->isOne();
}
static Value *checkArraySize(Value *Amt, const Type *IntPtrTy) {
if (!Amt)
Amt = ConstantInt::get(IntPtrTy, 1);
else {
assert(!isa<BasicBlock>(Amt) &&
"Passed basic block into malloc size parameter! Use other ctor");
assert(Amt->getType() == IntPtrTy &&
"Malloc array size is not an intptr!");
}
return Amt;
}
static Value *createMalloc(Instruction *InsertBefore, BasicBlock *InsertAtEnd,
const Type *AllocTy, const Type *IntPtrTy,
Value *ArraySize, const Twine &NameStr) {
assert((!InsertBefore && InsertAtEnd || InsertBefore && !InsertAtEnd) &&
"createMalloc needs only InsertBefore or InsertAtEnd");
const PointerType *AllocPtrType = dyn_cast<PointerType>(AllocTy);
assert(AllocPtrType && "CreateMalloc passed a non-pointer allocation type");
ArraySize = checkArraySize(ArraySize, IntPtrTy);
// malloc(type) becomes i8 *malloc(size)
Value *AllocSize = ConstantExpr::getSizeOf(AllocPtrType->getElementType());
AllocSize = ConstantExpr::getTruncOrBitCast(cast<Constant>(AllocSize),
IntPtrTy);
if (!IsConstantOne(ArraySize))
if (IsConstantOne(AllocSize)) {
AllocSize = ArraySize; // Operand * 1 = Operand
} else if (Constant *CO = dyn_cast<Constant>(ArraySize)) {
Constant *Scale = ConstantExpr::getIntegerCast(CO, IntPtrTy,
false /*ZExt*/);
// Malloc arg is constant product of type size and array size
AllocSize = ConstantExpr::getMul(Scale, cast<Constant>(AllocSize));
} else {
Value *Scale = ArraySize;
if (Scale->getType() != IntPtrTy)
if (InsertBefore)
Scale = CastInst::CreateIntegerCast(Scale, IntPtrTy, false /*ZExt*/,
"", InsertBefore);
else
Scale = CastInst::CreateIntegerCast(Scale, IntPtrTy, false /*ZExt*/,
"", InsertAtEnd);
// Multiply type size by the array size...
if (InsertBefore)
AllocSize = BinaryOperator::CreateMul(Scale, AllocSize,
"", InsertBefore);
else
AllocSize = BinaryOperator::CreateMul(Scale, AllocSize,
"", InsertAtEnd);
}
// Create the call to Malloc.
BasicBlock* BB = InsertBefore ? InsertBefore->getParent() : InsertAtEnd;
Module* M = BB->getParent()->getParent();
const Type *BPTy = PointerType::getUnqual(Type::getInt8Ty(BB->getContext()));
// prototype malloc as "void *malloc(size_t)"
Constant *MallocFunc = M->getOrInsertFunction("malloc", BPTy,
IntPtrTy, NULL);
CallInst *MCall = NULL;
if (InsertBefore)
MCall = CallInst::Create(MallocFunc, AllocSize, NameStr, InsertBefore);
else
MCall = CallInst::Create(MallocFunc, AllocSize, NameStr, InsertAtEnd);
MCall->setTailCall();
// Create a cast instruction to convert to the right type...
const Type* VoidT = Type::getVoidTy(BB->getContext());
assert(MCall->getType() != VoidT && "Malloc has void return type");
Value *MCast;
if (InsertBefore)
MCast = new BitCastInst(MCall, AllocPtrType, NameStr, InsertBefore);
else
MCast = new BitCastInst(MCall, AllocPtrType, NameStr);
return MCast;
}
/// CreateMalloc - Generate the IR for a call to malloc:
/// 1. Compute the malloc call's argument as the specified type's size,
/// possibly multiplied by the array size if the array size is not
/// constant 1.
/// 2. Call malloc with that argument.
/// 3. Bitcast the result of the malloc call to the specified type.
Value *CallInst::CreateMalloc(Instruction *InsertBefore,
const Type *AllocTy, const Type *IntPtrTy,
Value *ArraySize, const Twine &NameStr) {
return createMalloc(InsertBefore, NULL, AllocTy,
IntPtrTy, ArraySize, NameStr);
}
/// CreateMalloc - Generate the IR for a call to malloc:
/// 1. Compute the malloc call's argument as the specified type's size,
/// possibly multiplied by the array size if the array size is not
/// constant 1.
/// 2. Call malloc with that argument.
/// 3. Bitcast the result of the malloc call to the specified type.
/// Note: This function does not add the bitcast to the basic block, that is the
/// responsibility of the caller.
Value *CallInst::CreateMalloc(BasicBlock *InsertAtEnd,
const Type *AllocTy, const Type *IntPtrTy,
Value *ArraySize, const Twine &NameStr) {
return createMalloc(NULL, InsertAtEnd, AllocTy,
IntPtrTy, ArraySize, NameStr);
}
//===----------------------------------------------------------------------===//
// InvokeInst Implementation