ControlFlowGraph::BlockPointerVector ControlFlowGraph::pre_order_sequence() {
typedef std::unordered_set<iterator> BlockSet;
typedef std::stack<iterator> Stack;
BlockSet visited;
BlockPointerVector sequence;
Stack stack;
if (!empty()) {
stack.push(get_entry_block());
visited.insert(get_entry_block());
}
while (!stack.empty()) {
iterator current = stack.top();
stack.pop();
sequence.push_back(current);
// favor the fallthrough
iterator fallthrough = end();
if (current->has_fallthrough_edge()) {
edge_iterator fallthroughEdge
= sequence.back()->get_fallthrough_edge();
if (visited.insert(fallthroughEdge->tail).second) {
fallthrough = fallthroughEdge->tail;
}
}
for (pointer_iterator block = current->successors.begin();
block != current->successors.end(); ++block) {
if (visited.insert(*block).second) {
stack.push(*block);
}
}
if (fallthrough != end()) {
stack.push(fallthrough);
}
}
return sequence;
}
ControlFlowGraph::BlockPointerVector ControlFlowGraph::executable_sequence() {
typedef std::unordered_set<iterator> BlockSet;
BlockPointerVector sequence;
BlockSet unscheduled;
for(iterator i = begin(); i != end(); ++i)
{
unscheduled.insert(i);
}
report("Getting executable sequence.");
sequence.push_back(get_entry_block());
unscheduled.erase(get_entry_block());
report(" added " << get_entry_block()->label());
while (!unscheduled.empty()) {
if (sequence.back()->has_fallthrough_edge()) {
edge_iterator fallthroughEdge
= sequence.back()->get_fallthrough_edge();
if (unscheduled.count(fallthroughEdge->tail) != 0) {
sequence.push_back(fallthroughEdge->tail);
unscheduled.erase(fallthroughEdge->tail);
}
}
else {
// find a new block, favor branch targets over random blocks
iterator next = *unscheduled.begin();
for(edge_pointer_iterator edge = sequence.back()->out_edges.begin();
edge != sequence.back()->out_edges.end(); ++edge)
{
if(unscheduled.count((*edge)->tail) != 0)
{
next = (*edge)->tail;
}
}
// rewind through fallthrough edges to find the beginning of the
// next chain of fall throughs
report(" restarting at " << next->label());
bool rewinding = true;
while (rewinding) {
rewinding = false;
for (edge_pointer_iterator edge = next->in_edges.begin();
edge != next->in_edges.end(); ++edge) {
if ((*edge)->type == Edge::FallThrough) {
assertM(unscheduled.count((*edge)->head) != 0,
(*edge)->head->label()
<< " has multiple fallthrough branches.");
next = (*edge)->head;
report(" rewinding to " << next->label() );
rewinding = true;
break;
}
}
}
sequence.push_back(next);
unscheduled.erase(next);
}
report(" added " << sequence.back()->label());
}
return sequence;
}