bool CfgNaive::runOnFunction(Function &F) {
errs() << F.getName() << "\n";
SmallPtrSet<BasicBlock*, 8> visitedBlocks;
// Mark all reachable blocks.
for (df_ext_iterator<Function*, SmallPtrSet<BasicBlock*, 8>> currentBlock = df_ext_begin(&F, visitedBlocks),
endBlock = df_ext_end(&F, visitedBlocks);
currentBlock != endBlock;
currentBlock++) {
//do nothing, iterator marks visited nodes automatically
}
// Build set of unreachable blocks
std::vector<BasicBlock*> unreachableBlocks;
for (Function::iterator currentBlock = F.begin(), endBlock = F.end(); currentBlock != endBlock; currentBlock++) {
if (visitedBlocks.count(currentBlock) == 0) {
unreachableBlocks.push_back(currentBlock);
}
}
// Remove unreachable blocks
for (int i = 0, e = unreachableBlocks.size(); i != e; i++) {
errs() << unreachableBlocks[i]->getName() << " is unreachable\n";
unreachableBlocks[i]->eraseFromParent();
}
bool hasModifiedBlocks = (unreachableBlocks.size() > 0);
return hasModifiedBlocks;
}
bool DeadBlocks::runOnFunction(Function& F)
{
BasicBlock* entry = F.begin();
bool changed = false;
std::set<BasicBlock*> visitedSet;
std::set<BasicBlock*> unvisitedSet;
//Perform DFS from entry block
for (df_ext_iterator<BasicBlock*> dfi = df_ext_begin(entry,visitedSet),
endi = df_ext_end(entry, visitedSet); dfi != endi; ++dfi)
{
}
// Store unvisited blocks
for(auto& BB : F)
{
auto search = visitedSet.find(&BB);
if(search == visitedSet.end()) // if not in visited set
{
unvisitedSet.insert(&BB); // blocks to be removed...
}
}
if(unvisitedSet.size() > 0)
{
changed = true;
for(auto& BB : unvisitedSet)
{
for(succ_iterator SI = succ_begin(BB), SE = succ_end(BB);
SI != SE; SI++)
{
SI->removePredecessor(BB);
}
BB->eraseFromParent();
}
}
return changed;
}
