/*
* Build information about functions that store on pointer arguments
* For simplification, we only consider a function to store on an argument
* if it has exactly one StoreInst to that argument and the arg has no other use.
*/
int DeadStoreEliminationPass::getFnThatStoreOnArgs(Module &M) {
int numStores = 0;
DEBUG(errs() << "Getting functions that store on arguments...\n");
for (Module::iterator F = M.begin(); F != M.end(); ++F) {
if (F->arg_empty() || F->isDeclaration()) continue;
// Get args
std::set<Value*> args;
for (Function::arg_iterator formalArgIter = F->arg_begin();
formalArgIter != F->arg_end(); ++formalArgIter) {
Value *formalArg = formalArgIter;
if (formalArg->getType()->isPointerTy()) {
args.insert(formalArg);
}
}
// Find stores on arguments
for (Function::iterator BB = F->begin(); BB != F->end(); ++BB) {
for (BasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) {
Instruction *inst = I;
if (!isa<StoreInst>(inst)) continue;
StoreInst *SI = dyn_cast<StoreInst>(inst);
Value *ptrOp = SI->getPointerOperand();
if (args.count(ptrOp) && ptrOp->hasNUses(1)) {
fnThatStoreOnArgs[F].insert(ptrOp);
numStores++;
DEBUG(errs() << " " << F->getName() << " stores on argument "
<< ptrOp->getName() << "\n"); }
}
}
}
DEBUG(errs() << "\n");
return numStores;
}
