// The weight on each edge is the increment required along any path that
// contains that edge.
void BallLarusDag::calculatePathNumbersFrom(BallLarusNode* node) {
if(node == getExit())
// The Exit node must be base case
node->setNumberPaths(1);
else {
unsigned sumPaths = 0;
BallLarusNode* succNode;
for(BLEdgeIterator succ = node->succBegin(), end = node->succEnd();
succ != end; succ++) {
if( (*succ)->getType() == BallLarusEdge::BACKEDGE ||
(*succ)->getType() == BallLarusEdge::SPLITEDGE )
continue;
(*succ)->setWeight(sumPaths);
succNode = (*succ)->getTarget();
if( !succNode->getNumberPaths() )
return;
sumPaths += succNode->getNumberPaths();
}
node->setNumberPaths(sumPaths);
}
}
// Calculate the path numbers by assigning edge increments as prescribed
// in Ball-Larus path profiling.
void BallLarusDag::calculatePathNumbers() {
BallLarusNode* node;
std::queue<BallLarusNode*> bfsQueue;
bfsQueue.push(getExit());
while(bfsQueue.size() > 0) {
node = bfsQueue.front();
DEBUG(dbgs() << "calculatePathNumbers on " << node->getName() << "\n");
bfsQueue.pop();
unsigned prevPathNumber = node->getNumberPaths();
calculatePathNumbersFrom(node);
// Check for DAG splitting
if( node->getNumberPaths() > 100000000 && node != getRoot() ) {
// Add new phony edge from the split-node to the DAG's exit
BallLarusEdge* exitEdge = addEdge(node, getExit(), 0);
exitEdge->setType(BallLarusEdge::SPLITEDGE_PHONY);
// Counters to handle the possibility of a multi-graph
BasicBlock* oldTarget = 0;
unsigned duplicateNumber = 0;
// Iterate through each successor edge, adding phony edges
for( BLEdgeIterator succ = node->succBegin(), end = node->succEnd();
succ != end; oldTarget = (*succ)->getTarget()->getBlock(), succ++ ) {
if( (*succ)->getType() == BallLarusEdge::NORMAL ) {
// is this edge a duplicate?
if( oldTarget != (*succ)->getTarget()->getBlock() )
duplicateNumber = 0;
// create the new phony edge: root -> succ
BallLarusEdge* rootEdge =
addEdge(getRoot(), (*succ)->getTarget(), duplicateNumber++);
rootEdge->setType(BallLarusEdge::SPLITEDGE_PHONY);
rootEdge->setRealEdge(*succ);
// split on this edge and reference it's exit/root phony edges
(*succ)->setType(BallLarusEdge::SPLITEDGE);
(*succ)->setPhonyRoot(rootEdge);
(*succ)->setPhonyExit(exitEdge);
(*succ)->setWeight(0);
}
}
calculatePathNumbersFrom(node);
}
DEBUG(dbgs() << "prev, new number paths " << prevPathNumber << ", "
<< node->getNumberPaths() << ".\n");
if(prevPathNumber == 0 && node->getNumberPaths() != 0) {
DEBUG(dbgs() << "node ready : " << node->getName() << "\n");
for(BLEdgeIterator pred = node->predBegin(), end = node->predEnd();
pred != end; pred++) {
if( (*pred)->getType() == BallLarusEdge::BACKEDGE ||
(*pred)->getType() == BallLarusEdge::SPLITEDGE )
continue;
BallLarusNode* nextNode = (*pred)->getSource();
// not yet visited?
if(nextNode->getNumberPaths() == 0)
bfsQueue.push(nextNode);
}
}
}
DEBUG(dbgs() << "\tNumber of paths: " << getRoot()->getNumberPaths() << "\n");
}