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+//=-- ExplodedGraph.cpp - Local, Path-Sens. "Exploded Graph" -*- C++ -*------=//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the template classes ExplodedNode and ExplodedGraph,
+// which represent a path-sensitive, intra-procedural "exploded graph."
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/GRState.h"
+#include "clang/AST/Stmt.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallVector.h"
+#include <vector>
+
+using namespace clang;
+using namespace ento;
+
+//===----------------------------------------------------------------------===//
+// Node auditing.
+//===----------------------------------------------------------------------===//
+
+// An out of line virtual method to provide a home for the class vtable.
+ExplodedNode::Auditor::~Auditor() {}
+
+#ifndef NDEBUG
+static ExplodedNode::Auditor* NodeAuditor = 0;
+#endif
+
+void ExplodedNode::SetAuditor(ExplodedNode::Auditor* A) {
+#ifndef NDEBUG
+ NodeAuditor = A;
+#endif
+}
+
+//===----------------------------------------------------------------------===//
+// Cleanup.
+//===----------------------------------------------------------------------===//
+
+typedef std::vector<ExplodedNode*> NodeList;
+static inline NodeList*& getNodeList(void *&p) { return (NodeList*&) p; }
+
+ExplodedGraph::~ExplodedGraph() {
+ if (reclaimNodes) {
+ delete getNodeList(recentlyAllocatedNodes);
+ delete getNodeList(freeNodes);
+ }
+}
+
+//===----------------------------------------------------------------------===//
+// Node reclamation.
+//===----------------------------------------------------------------------===//
+
+void ExplodedGraph::reclaimRecentlyAllocatedNodes() {
+ if (!recentlyAllocatedNodes)
+ return;
+ NodeList &nl = *getNodeList(recentlyAllocatedNodes);
+
+ // Reclaimn all nodes that match *all* the following criteria:
+ //
+ // (1) 1 predecessor (that has one successor)
+ // (2) 1 successor (that has one predecessor)
+ // (3) The ProgramPoint is for a PostStmt.
+ // (4) There is no 'tag' for the ProgramPoint.
+ // (5) The 'store' is the same as the predecessor.
+ // (6) The 'GDM' is the same as the predecessor.
+ // (7) The LocationContext is the same as the predecessor.
+ // (8) The PostStmt is for a non-CFGElement expression.
+
+ for (NodeList::iterator i = nl.begin(), e = nl.end() ; i != e; ++i) {
+ ExplodedNode *node = *i;
+
+ // Conditions 1 and 2.
+ if (node->pred_size() != 1 || node->succ_size() != 1)
+ continue;
+
+ ExplodedNode *pred = *(node->pred_begin());
+ if (pred->succ_size() != 1)
+ continue;
+
+ ExplodedNode *succ = *(node->succ_begin());
+ if (succ->pred_size() != 1)
+ continue;
+
+ // Condition 3.
+ ProgramPoint progPoint = node->getLocation();
+ if (!isa<PostStmt>(progPoint))
+ continue;
+
+ // Condition 4.
+ PostStmt ps = cast<PostStmt>(progPoint);
+ if (ps.getTag() || isa<PostStmtCustom>(ps))
+ continue;
+
+ if (isa<BinaryOperator>(ps.getStmt()))
+ continue;
+
+ // Conditions 5, 6, and 7.
+ const GRState *state = node->getState();
+ const GRState *pred_state = pred->getState();
+ if (state->store != pred_state->store || state->GDM != pred_state->GDM ||
+ progPoint.getLocationContext() != pred->getLocationContext())
+ continue;
+
+ // Condition 8.
+ if (node->getCFG().isBlkExpr(ps.getStmt()))
+ continue;
+
+ // If we reach here, we can remove the node. This means:
+ // (a) changing the predecessors successor to the successor of this node
+ // (b) changing the successors predecessor to the predecessor of this node
+ // (c) Putting 'node' onto freeNodes.
+ pred->replaceSuccessor(succ);
+ succ->replacePredecessor(pred);
+ if (!freeNodes)
+ freeNodes = new NodeList();
+ getNodeList(freeNodes)->push_back(node);
+ Nodes.RemoveNode(node);
+ --NumNodes;
+ node->~ExplodedNode();
+ }
+
+ nl.clear();
+}
+
+//===----------------------------------------------------------------------===//
+// ExplodedNode.
+//===----------------------------------------------------------------------===//
+
+static inline BumpVector<ExplodedNode*>& getVector(void* P) {
+ return *reinterpret_cast<BumpVector<ExplodedNode*>*>(P);
+}
+
+void ExplodedNode::addPredecessor(ExplodedNode* V, ExplodedGraph &G) {
+ assert (!V->isSink());
+ Preds.addNode(V, G);
+ V->Succs.addNode(this, G);
+#ifndef NDEBUG
+ if (NodeAuditor) NodeAuditor->AddEdge(V, this);
+#endif
+}
+
+void ExplodedNode::NodeGroup::replaceNode(ExplodedNode *node) {
+ assert(getKind() == Size1);
+ P = reinterpret_cast<uintptr_t>(node);
+ assert(getKind() == Size1);
+}
+
+void ExplodedNode::NodeGroup::addNode(ExplodedNode* N, ExplodedGraph &G) {
+ assert((reinterpret_cast<uintptr_t>(N) & Mask) == 0x0);
+ assert(!getFlag());
+
+ if (getKind() == Size1) {
+ if (ExplodedNode* NOld = getNode()) {
+ BumpVectorContext &Ctx = G.getNodeAllocator();
+ BumpVector<ExplodedNode*> *V =
+ G.getAllocator().Allocate<BumpVector<ExplodedNode*> >();
+ new (V) BumpVector<ExplodedNode*>(Ctx, 4);
+
+ assert((reinterpret_cast<uintptr_t>(V) & Mask) == 0x0);
+ V->push_back(NOld, Ctx);
+ V->push_back(N, Ctx);
+ P = reinterpret_cast<uintptr_t>(V) | SizeOther;
+ assert(getPtr() == (void*) V);
+ assert(getKind() == SizeOther);
+ }
+ else {
+ P = reinterpret_cast<uintptr_t>(N);
+ assert(getKind() == Size1);
+ }
+ }
+ else {
+ assert(getKind() == SizeOther);
+ getVector(getPtr()).push_back(N, G.getNodeAllocator());
+ }
+}
+
+unsigned ExplodedNode::NodeGroup::size() const {
+ if (getFlag())
+ return 0;
+
+ if (getKind() == Size1)
+ return getNode() ? 1 : 0;
+ else
+ return getVector(getPtr()).size();
+}
+
+ExplodedNode **ExplodedNode::NodeGroup::begin() const {
+ if (getFlag())
+ return NULL;
+
+ if (getKind() == Size1)
+ return (ExplodedNode**) (getPtr() ? &P : NULL);
+ else
+ return const_cast<ExplodedNode**>(&*(getVector(getPtr()).begin()));
+}
+
+ExplodedNode** ExplodedNode::NodeGroup::end() const {
+ if (getFlag())
+ return NULL;
+
+ if (getKind() == Size1)
+ return (ExplodedNode**) (getPtr() ? &P+1 : NULL);
+ else {
+ // Dereferencing end() is undefined behaviour. The vector is not empty, so
+ // we can dereference the last elem and then add 1 to the result.
+ return const_cast<ExplodedNode**>(getVector(getPtr()).end());
+ }
+}
+
+ExplodedNode *ExplodedGraph::getNode(const ProgramPoint& L,
+ const GRState* State, bool* IsNew) {
+ // Profile 'State' to determine if we already have an existing node.
+ llvm::FoldingSetNodeID profile;
+ void* InsertPos = 0;
+
+ NodeTy::Profile(profile, L, State);
+ NodeTy* V = Nodes.FindNodeOrInsertPos(profile, InsertPos);
+
+ if (!V) {
+ if (freeNodes && !getNodeList(freeNodes)->empty()) {
+ NodeList *nl = getNodeList(freeNodes);
+ V = nl->back();
+ nl->pop_back();
+ }
+ else {
+ // Allocate a new node.
+ V = (NodeTy*) getAllocator().Allocate<NodeTy>();
+ }
+
+ new (V) NodeTy(L, State);
+
+ if (reclaimNodes) {
+ if (!recentlyAllocatedNodes)
+ recentlyAllocatedNodes = new NodeList();
+ getNodeList(recentlyAllocatedNodes)->push_back(V);
+ }
+
+ // Insert the node into the node set and return it.
+ Nodes.InsertNode(V, InsertPos);
+
+ ++NumNodes;
+
+ if (IsNew) *IsNew = true;
+ }
+ else
+ if (IsNew) *IsNew = false;
+
+ return V;
+}
+
+std::pair<ExplodedGraph*, InterExplodedGraphMap*>
+ExplodedGraph::Trim(const NodeTy* const* NBeg, const NodeTy* const* NEnd,
+ llvm::DenseMap<const void*, const void*> *InverseMap) const {
+
+ if (NBeg == NEnd)
+ return std::make_pair((ExplodedGraph*) 0,
+ (InterExplodedGraphMap*) 0);
+
+ assert (NBeg < NEnd);
+
+ llvm::OwningPtr<InterExplodedGraphMap> M(new InterExplodedGraphMap());
+
+ ExplodedGraph* G = TrimInternal(NBeg, NEnd, M.get(), InverseMap);
+
+ return std::make_pair(static_cast<ExplodedGraph*>(G), M.take());
+}
+
+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;
+
+ llvm::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** 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, NULL);
+ 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 **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 **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);
+ }
+
+ // Finally, explictly mark all nodes without any successors as sinks.
+ if (N->isSink())
+ NewN->markAsSink();
+ }
+
+ return G;
+}
+
+ExplodedNode*
+InterExplodedGraphMap::getMappedNode(const ExplodedNode* N) const {
+ llvm::DenseMap<const ExplodedNode*, ExplodedNode*>::const_iterator I =
+ M.find(N);
+
+ return I == M.end() ? 0 : I->second;
+}
+
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