static Value::use_iterator skipToNextUser(Value::use_iterator I,
Value::use_iterator End) {
User *CurUser = I->getUser();
++I;
while (I != End && I->getUser() == CurUser)
++I;
return I;
}
void DuettoNativeRewriter::rewriteConstructorImplementation(Module& M, Function& F)
{
//Copy the code in a function with the right signature
Function* newFunc=getReturningConstructor(M, &F);
if(!newFunc->empty())
return;
//Visit each instruction and take note of the ones that needs to be replaced
Function::const_iterator B=F.begin();
Function::const_iterator BE=F.end();
ValueToValueMapTy valueMap;
CallInst* lowerConstructor = NULL;
const CallInst* oldLowerConstructor = NULL;
for(;B!=BE;++B)
{
BasicBlock::const_iterator I=B->begin();
BasicBlock::const_iterator IE=B->end();
for(;I!=IE;++I)
{
if(I->getOpcode()!=Instruction::Call)
continue;
const CallInst* callInst=cast<CallInst>(&(*I));
Function* f=callInst->getCalledFunction();
if(!f)
continue;
const char* startOfType;
const char* endOfType;
if(!DuettoNativeRewriter::isBuiltinConstructor(f->getName().data(), startOfType, endOfType))
continue;
//Check that the constructor is for 'this'
if(callInst->getOperand(0)!=F.arg_begin())
continue;
//If this is another constructor for the same type, change it to a
//returning constructor and use it as the 'this' argument
Function* newFunc = getReturningConstructor(M, f);
llvm::SmallVector<Value*, 4> newArgs;
for(unsigned i=1;i<callInst->getNumArgOperands();i++)
newArgs.push_back(callInst->getArgOperand(i));
lowerConstructor = CallInst::Create(newFunc, newArgs);
oldLowerConstructor = callInst;
break;
}
if(lowerConstructor)
break;
}
//Clone the linkage first
newFunc->setLinkage(F.getLinkage());
Function::arg_iterator origArg=++F.arg_begin();
Function::arg_iterator newArg=newFunc->arg_begin();
valueMap.insert(make_pair(F.arg_begin(), lowerConstructor));
for(unsigned i=1;i<F.arg_size();i++)
{
valueMap.insert(make_pair(&(*origArg), &(*newArg)));
++origArg;
++newArg;
}
SmallVector<ReturnInst*, 4> returns;
CloneFunctionInto(newFunc, &F, valueMap, false, returns);
//Find the right place to add the base construtor call
assert(lowerConstructor->getNumArgOperands()<=1 && "Native constructors with multiple args are not supported");
Instruction* callPred = NULL;
if (lowerConstructor->getNumArgOperands()==1 && Instruction::classof(lowerConstructor->getArgOperand(0)))
{
//Switch the argument to the one in the new func
lowerConstructor->setArgOperand(0, valueMap[lowerConstructor->getArgOperand(0)]);
callPred = cast<Instruction>(lowerConstructor->getArgOperand(0));
}
else
callPred = &newFunc->getEntryBlock().front();
//Add add it
lowerConstructor->insertAfter(callPred);
//Override the returs values
for(unsigned i=0;i<returns.size();i++)
{
Instruction* newInst = ReturnInst::Create(M.getContext(),lowerConstructor);
newInst->insertBefore(returns[i]);
returns[i]->removeFromParent();
}
//Recursively move all the users of the lower constructor after the call itself
Instruction* insertPoint = lowerConstructor->getNextNode();
SmallVector<Value*, 4> usersQueue(lowerConstructor->getNumUses());
unsigned int i;
Value::use_iterator it;
for(i=usersQueue.size()-1,it=lowerConstructor->use_begin();it!=lowerConstructor->use_end();++it,i--)
usersQueue[i]=it->getUser();
SmallSet<Instruction*, 4> movedInstructions;
while(!usersQueue.empty())
{
Instruction* cur=dyn_cast<Instruction>(usersQueue.pop_back_val());
if(!cur)
continue;
if(movedInstructions.count(cur))
continue;
movedInstructions.insert(cur);
cur->moveBefore(insertPoint);
//Add users of this instrucution as well
usersQueue.resize(usersQueue.size()+cur->getNumUses());
for(i=usersQueue.size()-1,it=cur->use_begin();it!=cur->use_end();++it,i--)
usersQueue[i]=it->getUser();
}
cast<Instruction>(valueMap[oldLowerConstructor])->eraseFromParent();
}