ExplodedGraph*
ExplodedGraph::TrimInternal(const ExplodedNode* const* BeginSources,
const ExplodedNode* const* EndSources,
InterExplodedGraphMap* M,
llvm::DenseMap<const void*, const void*> *InverseMap) const {
typedef llvm::DenseSet<const ExplodedNode*> Pass1Ty;
Pass1Ty Pass1;
typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> Pass2Ty;
Pass2Ty& Pass2 = M->M;
SmallVector<const ExplodedNode*, 10> WL1, WL2;
// ===- Pass 1 (reverse DFS) -===
for (const ExplodedNode* const* I = BeginSources; I != EndSources; ++I) {
assert(*I);
WL1.push_back(*I);
}
// Process the first worklist until it is empty. Because it is a std::list
// it acts like a FIFO queue.
while (!WL1.empty()) {
const ExplodedNode *N = WL1.back();
WL1.pop_back();
// Have we already visited this node? If so, continue to the next one.
if (Pass1.count(N))
continue;
// Otherwise, mark this node as visited.
Pass1.insert(N);
// If this is a root enqueue it to the second worklist.
if (N->Preds.empty()) {
WL2.push_back(N);
continue;
}
// Visit our predecessors and enqueue them.
for (ExplodedNode::pred_iterator I = N->Preds.begin(), E = N->Preds.end();
I != E; ++I)
WL1.push_back(*I);
}
// We didn't hit a root? Return with a null pointer for the new graph.
if (WL2.empty())
return 0;
// Create an empty graph.
ExplodedGraph* G = MakeEmptyGraph();
// ===- Pass 2 (forward DFS to construct the new graph) -===
while (!WL2.empty()) {
const ExplodedNode *N = WL2.back();
WL2.pop_back();
// Skip this node if we have already processed it.
if (Pass2.find(N) != Pass2.end())
continue;
// Create the corresponding node in the new graph and record the mapping
// from the old node to the new node.
ExplodedNode *NewN = G->getNode(N->getLocation(), N->State, N->isSink(), 0);
Pass2[N] = NewN;
// Also record the reverse mapping from the new node to the old node.
if (InverseMap) (*InverseMap)[NewN] = N;
// If this node is a root, designate it as such in the graph.
if (N->Preds.empty())
G->addRoot(NewN);
// In the case that some of the intended predecessors of NewN have already
// been created, we should hook them up as predecessors.
// Walk through the predecessors of 'N' and hook up their corresponding
// nodes in the new graph (if any) to the freshly created node.
for (ExplodedNode::pred_iterator I = N->Preds.begin(), E = N->Preds.end();
I != E; ++I) {
Pass2Ty::iterator PI = Pass2.find(*I);
if (PI == Pass2.end())
continue;
NewN->addPredecessor(PI->second, *G);
}
// In the case that some of the intended successors of NewN have already
// been created, we should hook them up as successors. Otherwise, enqueue
// the new nodes from the original graph that should have nodes created
// in the new graph.
for (ExplodedNode::succ_iterator I = N->Succs.begin(), E = N->Succs.end();
I != E; ++I) {
Pass2Ty::iterator PI = Pass2.find(*I);
if (PI != Pass2.end()) {
PI->second->addPredecessor(NewN, *G);
continue;
}
// Enqueue nodes to the worklist that were marked during pass 1.
if (Pass1.count(*I))
WL2.push_back(*I);
}
}
return G;
}
