// Process an edge in the CFG for DAG building.
void BallLarusDag::buildEdge(BLBlockNodeMap& inDag, std::stack<BallLarusNode*>&
dfsStack, BallLarusNode* currentNode,
BasicBlock* succBB, unsigned duplicateCount) {
BallLarusNode* succNode = inDag[succBB];
if(succNode && succNode->getColor() == BallLarusNode::BLACK) {
// visited node and forward edge
addEdge(currentNode, succNode, duplicateCount);
} else if(succNode && succNode->getColor() == BallLarusNode::GRAY) {
// visited node and back edge
DEBUG(dbgs() << "Backedge detected.\n");
addBackedge(currentNode, succNode, duplicateCount);
} else {
BallLarusNode* childNode;
// not visited node and forward edge
if(succNode) // an unvisited node that is child of a gray node
childNode = succNode;
else { // an unvisited node that is a child of a an unvisted node
childNode = addNode(succBB);
inDag[succBB] = childNode;
}
addEdge(currentNode, childNode, duplicateCount);
dfsStack.push(childNode);
}
}
// Processes one node and its imediate edges for building the DAG.
void BallLarusDag::buildNode(BLBlockNodeMap& inDag, BLNodeStack& dfsStack) {
BallLarusNode* currentNode = dfsStack.top();
BasicBlock* currentBlock = currentNode->getBlock();
if(currentNode->getColor() != BallLarusNode::WHITE) {
// we have already visited this node
dfsStack.pop();
currentNode->setColor(BallLarusNode::BLACK);
} else {
// are there any external procedure calls?
if( ProcessEarlyTermination ) {
for( BasicBlock::iterator bbCurrent = currentNode->getBlock()->begin(),
bbEnd = currentNode->getBlock()->end(); bbCurrent != bbEnd;
bbCurrent++ ) {
Instruction& instr = *bbCurrent;
if( instr.getOpcode() == Instruction::Call ) {
BallLarusEdge* callEdge = addEdge(currentNode, getExit(), 0);
callEdge->setType(BallLarusEdge::CALLEDGE_PHONY);
break;
}
}
}
TerminatorInst* terminator = currentNode->getBlock()->getTerminator();
if(isa<ReturnInst>(terminator) || isa<UnreachableInst>(terminator)
|| isa<UnwindInst>(terminator))
addEdge(currentNode, getExit(),0);
currentNode->setColor(BallLarusNode::GRAY);
inDag[currentBlock] = currentNode;
BasicBlock* oldSuccessor = 0;
unsigned duplicateNumber = 0;
// iterate through this node's successors
for(succ_iterator successor = succ_begin(currentBlock),
succEnd = succ_end(currentBlock); successor != succEnd;
oldSuccessor = *successor, ++successor ) {
BasicBlock* succBB = *successor;
// is this edge a duplicate?
if (oldSuccessor == succBB)
duplicateNumber++;
else
duplicateNumber = 0;
buildEdge(inDag, dfsStack, currentNode, succBB, duplicateNumber);
}
}
}