Exemplo n.º 1
0
void ExplodedNode::NodeGroup::addNode(ExplodedNode *N, ExplodedGraph &G) {
  assert(!getFlag());

  GroupStorage &Storage = reinterpret_cast<GroupStorage&>(P);
  if (Storage.isNull()) {
    Storage = N;
    assert(Storage.is<ExplodedNode *>());
    return;
  }

  ExplodedNodeVector *V = Storage.dyn_cast<ExplodedNodeVector *>();

  if (!V) {
    // Switch from single-node to multi-node representation.
    ExplodedNode *Old = Storage.get<ExplodedNode *>();

    BumpVectorContext &Ctx = G.getNodeAllocator();
    V = G.getAllocator().Allocate<ExplodedNodeVector>();
    new (V) ExplodedNodeVector(Ctx, 4);
    V->push_back(Old, Ctx);

    Storage = V;
    assert(!getFlag());
    assert(Storage.is<ExplodedNodeVector *>());
  }

  V->push_back(N, G.getNodeAllocator());
}
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());
  }
}
void UnreachableCodeChecker::checkEndAnalysis(ExplodedGraph &G,
                                              BugReporter &B,
                                              ExprEngine &Eng) const {
  CFGBlocksSet reachable, visited;

  if (Eng.hasWorkRemaining())
    return;

  const Decl *D = nullptr;
  CFG *C = nullptr;
  ParentMap *PM = nullptr;
  const LocationContext *LC = nullptr;
  // Iterate over ExplodedGraph
  for (ExplodedGraph::node_iterator I = G.nodes_begin(), E = G.nodes_end();
      I != E; ++I) {
    const ProgramPoint &P = I->getLocation();
    LC = P.getLocationContext();
    if (!LC->inTopFrame())
      continue;

    if (!D)
      D = LC->getAnalysisDeclContext()->getDecl();

    // Save the CFG if we don't have it already
    if (!C)
      C = LC->getAnalysisDeclContext()->getUnoptimizedCFG();
    if (!PM)
      PM = &LC->getParentMap();

    if (Optional<BlockEntrance> BE = P.getAs<BlockEntrance>()) {
      const CFGBlock *CB = BE->getBlock();
      reachable.insert(CB->getBlockID());
    }
  }

  // Bail out if we didn't get the CFG or the ParentMap.
  if (!D || !C || !PM)
    return;

  // Don't do anything for template instantiations.  Proving that code
  // in a template instantiation is unreachable means proving that it is
  // unreachable in all instantiations.
  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
    if (FD->isTemplateInstantiation())
      return;

  // Find CFGBlocks that were not covered by any node
  for (CFG::const_iterator I = C->begin(), E = C->end(); I != E; ++I) {
    const CFGBlock *CB = *I;
    // Check if the block is unreachable
    if (reachable.count(CB->getBlockID()))
      continue;

    // Check if the block is empty (an artificial block)
    if (isEmptyCFGBlock(CB))
      continue;

    // Find the entry points for this block
    if (!visited.count(CB->getBlockID()))
      FindUnreachableEntryPoints(CB, reachable, visited);

    // This block may have been pruned; check if we still want to report it
    if (reachable.count(CB->getBlockID()))
      continue;

    // Check for false positives
    if (isInvalidPath(CB, *PM))
      continue;

    // It is good practice to always have a "default" label in a "switch", even
    // if we should never get there. It can be used to detect errors, for
    // instance. Unreachable code directly under a "default" label is therefore
    // likely to be a false positive.
    if (const Stmt *label = CB->getLabel())
      if (label->getStmtClass() == Stmt::DefaultStmtClass)
        continue;

    // Special case for __builtin_unreachable.
    // FIXME: This should be extended to include other unreachable markers,
    // such as llvm_unreachable.
    if (!CB->empty()) {
      bool foundUnreachable = false;
      for (CFGBlock::const_iterator ci = CB->begin(), ce = CB->end();
           ci != ce; ++ci) {
        if (Optional<CFGStmt> S = (*ci).getAs<CFGStmt>())
          if (const CallExpr *CE = dyn_cast<CallExpr>(S->getStmt())) {
            if (CE->getBuiltinCallee() == Builtin::BI__builtin_unreachable ||
                CE->isBuiltinAssumeFalse(Eng.getContext())) {
              foundUnreachable = true;
              break;
            }
          }
      }
      if (foundUnreachable)
        continue;
    }

    // We found a block that wasn't covered - find the statement to report
    SourceRange SR;
    PathDiagnosticLocation DL;
    SourceLocation SL;
    if (const Stmt *S = getUnreachableStmt(CB)) {
      // In macros, 'do {...} while (0)' is often used. Don't warn about the
      // condition 0 when it is unreachable.
      if (S->getBeginLoc().isMacroID())
        if (const auto *I = dyn_cast<IntegerLiteral>(S))
          if (I->getValue() == 0ULL)
            if (const Stmt *Parent = PM->getParent(S))
              if (isa<DoStmt>(Parent))
                continue;
      SR = S->getSourceRange();
      DL = PathDiagnosticLocation::createBegin(S, B.getSourceManager(), LC);
      SL = DL.asLocation();
      if (SR.isInvalid() || !SL.isValid())
        continue;
    }
    else
      continue;

    // Check if the SourceLocation is in a system header
    const SourceManager &SM = B.getSourceManager();
    if (SM.isInSystemHeader(SL) || SM.isInExternCSystemHeader(SL))
      continue;

    B.EmitBasicReport(D, this, "Unreachable code", "Dead code",
                      "This statement is never executed", DL, SR);
  }
}
void UnreachableCodeChecker::checkEndAnalysis(ExplodedGraph &G,
                                              BugReporter &B,
                                              ExprEngine &Eng) const {
  CFGBlocksSet reachable, visited;

  if (Eng.hasWorkRemaining())
    return;

  CFG *C = 0;
  ParentMap *PM = 0;
  // Iterate over ExplodedGraph
  for (ExplodedGraph::node_iterator I = G.nodes_begin(), E = G.nodes_end();
      I != E; ++I) {
    const ProgramPoint &P = I->getLocation();
    const LocationContext *LC = P.getLocationContext();

    // Save the CFG if we don't have it already
    if (!C)
      C = LC->getAnalysisContext()->getUnoptimizedCFG();
    if (!PM)
      PM = &LC->getParentMap();

    if (const BlockEntrance *BE = dyn_cast<BlockEntrance>(&P)) {
      const CFGBlock *CB = BE->getBlock();
      reachable.insert(CB->getBlockID());
    }
  }

  // Bail out if we didn't get the CFG or the ParentMap.
  if (!C || !PM)
    return;

  ASTContext &Ctx = B.getContext();

  // Find CFGBlocks that were not covered by any node
  for (CFG::const_iterator I = C->begin(), E = C->end(); I != E; ++I) {
    const CFGBlock *CB = *I;
    // Check if the block is unreachable
    if (reachable.count(CB->getBlockID()))
      continue;

    // Check if the block is empty (an artificial block)
    if (isEmptyCFGBlock(CB))
      continue;

    // Find the entry points for this block
    if (!visited.count(CB->getBlockID()))
      FindUnreachableEntryPoints(CB, reachable, visited);

    // This block may have been pruned; check if we still want to report it
    if (reachable.count(CB->getBlockID()))
      continue;

    // Check for false positives
    if (CB->size() > 0 && isInvalidPath(CB, *PM))
      continue;

    // Special case for __builtin_unreachable.
    // FIXME: This should be extended to include other unreachable markers,
    // such as llvm_unreachable.
    if (!CB->empty()) {
      CFGElement First = CB->front();
      if (const CFGStmt *S = First.getAs<CFGStmt>()) {
        if (const CallExpr *CE = dyn_cast<CallExpr>(S->getStmt())) {
          if (CE->isBuiltinCall(Ctx) == Builtin::BI__builtin_unreachable)
            continue;
        }
      }
    }

    // We found a block that wasn't covered - find the statement to report
    SourceRange SR;
    SourceLocation SL;
    if (const Stmt *S = getUnreachableStmt(CB)) {
      SR = S->getSourceRange();
      SL = S->getLocStart();
      if (SR.isInvalid() || SL.isInvalid())
        continue;
    }
    else
      continue;

    // Check if the SourceLocation is in a system header
    const SourceManager &SM = B.getSourceManager();
    if (SM.isInSystemHeader(SL) || SM.isInExternCSystemHeader(SL))
      continue;

    B.EmitBasicReport("Unreachable code", "Dead code", "This statement is never"
        " executed", SL, SR);
  }
}
Exemplo n.º 5
0
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;
}
Exemplo n.º 6
0
void AnalyzerStatsChecker::checkEndAnalysis(ExplodedGraph &G,
                                            BugReporter &B,
                                            ExprEngine &Eng) const {
  const CFG *C  = 0;
  const SourceManager &SM = B.getSourceManager();
  llvm::SmallPtrSet<const CFGBlock*, 256> reachable;

  // Root node should have the location context of the top most function.
  const ExplodedNode *GraphRoot = *G.roots_begin();
  const LocationContext *LC = GraphRoot->getLocation().getLocationContext();

  const Decl *D = LC->getDecl();

  // Iterate over the exploded graph.
  for (ExplodedGraph::node_iterator I = G.nodes_begin();
      I != G.nodes_end(); ++I) {
    const ProgramPoint &P = I->getLocation();

    // Only check the coverage in the top level function (optimization).
    if (D != P.getLocationContext()->getDecl())
      continue;

    if (const BlockEntrance *BE = dyn_cast<BlockEntrance>(&P)) {
      const CFGBlock *CB = BE->getBlock();
      reachable.insert(CB);
    }
  }

  // Get the CFG and the Decl of this block.
  C = LC->getCFG();

  unsigned total = 0, unreachable = 0;

  // Find CFGBlocks that were not covered by any node
  for (CFG::const_iterator I = C->begin(); I != C->end(); ++I) {
    const CFGBlock *CB = *I;
    ++total;
    // Check if the block is unreachable
    if (!reachable.count(CB)) {
      ++unreachable;
    }
  }

  // We never 'reach' the entry block, so correct the unreachable count
  unreachable--;
  // There is no BlockEntrance corresponding to the exit block as well, so
  // assume it is reached as well.
  unreachable--;

  // Generate the warning string
  SmallString<128> buf;
  llvm::raw_svector_ostream output(buf);
  PresumedLoc Loc = SM.getPresumedLoc(D->getLocation());
  if (!Loc.isValid())
    return;

  if (isa<FunctionDecl>(D) || isa<ObjCMethodDecl>(D)) {
    const NamedDecl *ND = cast<NamedDecl>(D);
    output << *ND;
  }
  else if (isa<BlockDecl>(D)) {
    output << "block(line:" << Loc.getLine() << ":col:" << Loc.getColumn();
  }

  NumBlocksUnreachable += unreachable;
  NumBlocks += total;
  std::string NameOfRootFunction = output.str();

  output << " -> Total CFGBlocks: " << total << " | Unreachable CFGBlocks: "
      << unreachable << " | Exhausted Block: "
      << (Eng.wasBlocksExhausted() ? "yes" : "no")
      << " | Empty WorkList: "
      << (Eng.hasEmptyWorkList() ? "yes" : "no");

  B.EmitBasicReport(D, "Analyzer Statistics", "Internal Statistics",
                    output.str(), PathDiagnosticLocation(D, SM));

  // Emit warning for each block we bailed out on.
  typedef CoreEngine::BlocksExhausted::const_iterator ExhaustedIterator;
  const CoreEngine &CE = Eng.getCoreEngine();
  for (ExhaustedIterator I = CE.blocks_exhausted_begin(),
      E = CE.blocks_exhausted_end(); I != E; ++I) {
    const BlockEdge &BE =  I->first;
    const CFGBlock *Exit = BE.getDst();
    const CFGElement &CE = Exit->front();
    if (const CFGStmt *CS = dyn_cast<CFGStmt>(&CE)) {
      SmallString<128> bufI;
      llvm::raw_svector_ostream outputI(bufI);
      outputI << "(" << NameOfRootFunction << ")" <<
                 ": The analyzer generated a sink at this point";
      B.EmitBasicReport(D, "Sink Point", "Internal Statistics", outputI.str(),
                        PathDiagnosticLocation::createBegin(CS->getStmt(),
                                                            SM, LC));
    }
  }
}
Exemplo n.º 7
0
void AnalyzerStatsChecker::checkEndAnalysis(ExplodedGraph &G,
        BugReporter &B,
        ExprEngine &Eng) const {
    const CFG *C  = 0;
    const Decl *D = 0;
    const LocationContext *LC = 0;
    const SourceManager &SM = B.getSourceManager();
    llvm::SmallPtrSet<const CFGBlock*, 256> reachable;

    // Iterate over explodedgraph
    for (ExplodedGraph::node_iterator I = G.nodes_begin();
            I != G.nodes_end(); ++I) {
        const ProgramPoint &P = I->getLocation();
        // Save the LocationContext if we don't have it already
        if (!LC)
            LC = P.getLocationContext();

        if (const BlockEntrance *BE = dyn_cast<BlockEntrance>(&P)) {
            const CFGBlock *CB = BE->getBlock();
            reachable.insert(CB);
        }
    }

    // Get the CFG and the Decl of this block
    C = LC->getCFG();
    D = LC->getAnalysisContext()->getDecl();

    unsigned total = 0, unreachable = 0;

    // Find CFGBlocks that were not covered by any node
    for (CFG::const_iterator I = C->begin(); I != C->end(); ++I) {
        const CFGBlock *CB = *I;
        ++total;
        // Check if the block is unreachable
        if (!reachable.count(CB)) {
            ++unreachable;
        }
    }

    // We never 'reach' the entry block, so correct the unreachable count
    unreachable--;

    // Generate the warning string
    llvm::SmallString<128> buf;
    llvm::raw_svector_ostream output(buf);
    PresumedLoc Loc = SM.getPresumedLoc(D->getLocation());
    if (Loc.isValid()) {
        output << Loc.getFilename() << " : ";

        if (isa<FunctionDecl>(D) || isa<ObjCMethodDecl>(D)) {
            const NamedDecl *ND = cast<NamedDecl>(D);
            output << ND;
        }
        else if (isa<BlockDecl>(D)) {
            output << "block(line:" << Loc.getLine() << ":col:" << Loc.getColumn();
        }
    }

    output << " -> Total CFGBlocks: " << total << " | Unreachable CFGBlocks: "
           << unreachable << " | Exhausted Block: "
           << (Eng.wasBlocksExhausted() ? "yes" : "no")
           << " | Empty WorkList: "
           << (Eng.hasEmptyWorkList() ? "yes" : "no");

    B.EmitBasicReport("Analyzer Statistics", "Internal Statistics", output.str(),
                      PathDiagnosticLocation(D, SM));

    // Emit warning for each block we bailed out on
    typedef CoreEngine::BlocksExhausted::const_iterator ExhaustedIterator;
    const CoreEngine &CE = Eng.getCoreEngine();
    for (ExhaustedIterator I = CE.blocks_exhausted_begin(),
            E = CE.blocks_exhausted_end(); I != E; ++I) {
        const BlockEdge &BE =  I->first;
        const CFGBlock *Exit = BE.getDst();
        const CFGElement &CE = Exit->front();
        if (const CFGStmt *CS = dyn_cast<CFGStmt>(&CE))
            B.EmitBasicReport("Bailout Point", "Internal Statistics", "The analyzer "
                              "stopped analyzing at this point",
                              PathDiagnosticLocation::createBegin(CS->getStmt(), SM, LC));
    }
}