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//===- RaiseAllocations.cpp - Convert %malloc & %free calls to insts ------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the RaiseAllocations pass which convert malloc and free
// calls to malloc and free instructions.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/IPO.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/Instructions.h"
#include "llvm/Pass.h"
#include "llvm/Support/CallSite.h"
#include "llvm/ADT/Statistic.h"
using namespace llvm;
namespace {
Statistic<> NumRaised("raiseallocs", "Number of allocations raised");
// RaiseAllocations - Turn %malloc and %free calls into the appropriate
// instruction.
//
class RaiseAllocations : public ModulePass {
Function *MallocFunc; // Functions in the module we are processing
Function *FreeFunc; // Initialized by doPassInitializationVirt
public:
RaiseAllocations() : MallocFunc(0), FreeFunc(0) {}
// doPassInitialization - For the raise allocations pass, this finds a
// declaration for malloc and free if they exist.
//
void doInitialization(Module &M);
// run - This method does the actual work of converting instructions over.
//
bool runOnModule(Module &M);
};
RegisterOpt<RaiseAllocations>
X("raiseallocs", "Raise allocations from calls to instructions");
} // end anonymous namespace
// createRaiseAllocationsPass - The interface to this file...
ModulePass *llvm::createRaiseAllocationsPass() {
return new RaiseAllocations();
}
// If the module has a symbol table, they might be referring to the malloc and
// free functions. If this is the case, grab the method pointers that the
// module is using.
//
// Lookup %malloc and %free in the symbol table, for later use. If they don't
// exist, or are not external, we do not worry about converting calls to that
// function into the appropriate instruction.
//
void RaiseAllocations::doInitialization(Module &M) {
const FunctionType *MallocType = // Get the type for malloc
FunctionType::get(PointerType::get(Type::SByteTy),
std::vector<const Type*>(1, Type::ULongTy), false);
const FunctionType *FreeType = // Get the type for free
FunctionType::get(Type::VoidTy,
std::vector<const Type*>(1, PointerType::get(Type::SByteTy)),
false);
// Get Malloc and free prototypes if they exist!
MallocFunc = M.getFunction("malloc", MallocType);
FreeFunc = M.getFunction("free" , FreeType);
// Check to see if the prototype is wrong, giving us sbyte*(uint) * malloc
// This handles the common declaration of: 'void *malloc(unsigned);'
if (MallocFunc == 0) {
MallocType = FunctionType::get(PointerType::get(Type::SByteTy),
std::vector<const Type*>(1, Type::UIntTy), false);
MallocFunc = M.getFunction("malloc", MallocType);
}
// Check to see if the prototype is missing, giving us sbyte*(...) * malloc
// This handles the common declaration of: 'void *malloc();'
if (MallocFunc == 0) {
MallocType = FunctionType::get(PointerType::get(Type::SByteTy),
std::vector<const Type*>(), true);
MallocFunc = M.getFunction("malloc", MallocType);
}
// Check to see if the prototype was forgotten, giving us void (...) * free
// This handles the common forward declaration of: 'void free();'
if (FreeFunc == 0) {
FreeType = FunctionType::get(Type::VoidTy, std::vector<const Type*>(),true);
FreeFunc = M.getFunction("free", FreeType);
}
// One last try, check to see if we can find free as 'int (...)* free'. This
// handles the case where NOTHING was declared.
if (FreeFunc == 0) {
FreeType = FunctionType::get(Type::IntTy, std::vector<const Type*>(),true);
FreeFunc = M.getFunction("free", FreeType);
}
// Don't mess with locally defined versions of these functions...
if (MallocFunc && !MallocFunc->isExternal()) MallocFunc = 0;
if (FreeFunc && !FreeFunc->isExternal()) FreeFunc = 0;
}
// run - Transform calls into instructions...
//
bool RaiseAllocations::runOnModule(Module &M) {
// Find the malloc/free prototypes...
doInitialization(M);
bool Changed = false;
// First, process all of the malloc calls...
if (MallocFunc) {
std::vector<User*> Users(MallocFunc->use_begin(), MallocFunc->use_end());
std::vector<Value*> EqPointers; // Values equal to MallocFunc
while (!Users.empty()) {
User *U = Users.back();
Users.pop_back();
if (Instruction *I = dyn_cast<Instruction>(U)) {
CallSite CS = CallSite::get(I);
if (CS.getInstruction() && CS.arg_begin() != CS.arg_end() &&
(CS.getCalledFunction() == MallocFunc ||
std::find(EqPointers.begin(), EqPointers.end(),
CS.getCalledValue()) != EqPointers.end())) {
Value *Source = *CS.arg_begin();
// If no prototype was provided for malloc, we may need to cast the
// source size.
if (Source->getType() != Type::UIntTy)
Source = new CastInst(Source, Type::UIntTy, "MallocAmtCast", I);
std::string Name(I->getName()); I->setName("");
MallocInst *MI = new MallocInst(Type::SByteTy, Source, Name, I);
I->replaceAllUsesWith(MI);
// If the old instruction was an invoke, add an unconditional branch
// before the invoke, which will become the new terminator.
if (InvokeInst *II = dyn_cast<InvokeInst>(I))
new BranchInst(II->getNormalDest(), I);
// Delete the old call site
MI->getParent()->getInstList().erase(I);
Changed = true;
++NumRaised;
}
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(U)) {
Users.insert(Users.end(), GV->use_begin(), GV->use_end());
EqPointers.push_back(GV);
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
if (CE->getOpcode() == Instruction::Cast) {
Users.insert(Users.end(), CE->use_begin(), CE->use_end());
EqPointers.push_back(CE);
}
}
}
}
// Next, process all free calls...
if (FreeFunc) {
std::vector<User*> Users(FreeFunc->use_begin(), FreeFunc->use_end());
std::vector<Value*> EqPointers; // Values equal to FreeFunc
while (!Users.empty()) {
User *U = Users.back();
Users.pop_back();
if (Instruction *I = dyn_cast<Instruction>(U)) {
CallSite CS = CallSite::get(I);
if (CS.getInstruction() && CS.arg_begin() != CS.arg_end() &&
(CS.getCalledFunction() == FreeFunc ||
std::find(EqPointers.begin(), EqPointers.end(),
CS.getCalledValue()) != EqPointers.end())) {
// If no prototype was provided for free, we may need to cast the
// source pointer. This should be really uncommon, but it's necessary
// just in case we are dealing with wierd code like this:
// free((long)ptr);
//
Value *Source = *CS.arg_begin();
if (!isa<PointerType>(Source->getType()))
Source = new CastInst(Source, PointerType::get(Type::SByteTy),
"FreePtrCast", I);
new FreeInst(Source, I);
// If the old instruction was an invoke, add an unconditional branch
// before the invoke, which will become the new terminator.
if (InvokeInst *II = dyn_cast<InvokeInst>(I))
new BranchInst(II->getNormalDest(), I);
// Delete the old call site
I->getParent()->getInstList().erase(I);
Changed = true;
++NumRaised;
}
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(U)) {
Users.insert(Users.end(), GV->use_begin(), GV->use_end());
EqPointers.push_back(GV);
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
if (CE->getOpcode() == Instruction::Cast) {
Users.insert(Users.end(), CE->use_begin(), CE->use_end());
EqPointers.push_back(CE);
}
}
}
}
return Changed;
}
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