C++ PEdge::GetSource方法代码示例

// fill in the body of loophead. points in the body are those which
// are reachable from loophead over non-backedges, and which themselves
// reach a backedge for loophead. note that in the case of loop nesting,
// a point may be contained in the body of multiple loops.
// if any irreducible edges are found (edges incoming to a body point
// other than loophead whose source is not in the body), those edges
// are added to irreducible_edges
void GetLoopBody(BlockCFG *cfg, PPoint loophead,
                 Vector<PEdge*> *irreducible_edges)
{
    Vector<PPoint> *body_list = body_list_table->Lookup(loophead, true);
    Assert(body_list->Empty());

    // worklist items are points which reach a loop backedge but whose
    // incoming edges have not yet been examined.
    Vector<PPoint> worklist;

    const Vector<PEdge*> &head_incoming = cfg->GetIncomingEdges(loophead);
    for (size_t iind = 0; iind < head_incoming.Size(); iind++) {
        PEdge *edge = head_incoming[iind];
        PPoint source = edge->GetSource();

        if (backedge_table->Lookup(edge)) {
            Assert(reach_table->Lookup(PPointPair(loophead, source)));

            if (!body_table->Insert(PPointPair(loophead, source))) {
                body_list->PushBack(source);
                worklist.PushBack(source);
            }
        }
    }

    // this should only be called on loops that have actual backedges
    Assert(!worklist.Empty());

    while (!worklist.Empty()) {
        PPoint back = worklist.Back();
        worklist.PopBack();

        if (back == loophead)
            continue;

        const Vector<PEdge*> &incoming = cfg->GetIncomingEdges(back);
        for (size_t iind = 0; iind < incoming.Size(); iind++) {
            PEdge *edge = incoming[iind];
            PPoint source = edge->GetSource();

            if (reach_table->Lookup(PPointPair(loophead, source))) {
                if (!body_table->Insert(PPointPair(loophead, source))) {
                    body_list->PushBack(source);
                    worklist.PushBack(source);
                }
            }
            else if (entry_reach_table->Lookup(source)) {
                // the source is not reachable from the loophead.
                // this is an irreducible edge.
                irreducible_edges->PushBack(edge);
            }
        }
    }
}

void BlockSummary::GetAssumedBits(BlockMemory *mcfg, PPoint end_point,
                                  Vector<AssumeInfo> *assume_list)
{
  BlockId *id = mcfg->GetId();
  BlockCFG *cfg = mcfg->GetCFG();

  BlockSummary *sum = GetBlockSummary(id);

  const Vector<Bit*> *assumes = sum->GetAssumes();
  size_t assume_count = VectorSize<Bit*>(assumes);

  // pull in assumptions from the summary for mcfg. in some cases these
  // assumptions won't be useful, e.g. describing the state at exit
  // for functions. for now we're just adding all of them though. TODO: fix.
  for (size_t ind = 0; ind < assume_count; ind++) {
    Bit *bit = assumes->At(ind);
    bit->IncRef(assume_list);

    AssumeInfo info;
    info.bit = bit;
    assume_list->PushBack(info);
  }

  sum->DecRef();

  Vector<BlockCFG*> *annot_list = BodyAnnotCache.Lookup(id->Function());

  // add assumes at function entry for any preconditions.

  if (id->Kind() == B_Function) {
    for (size_t ind = 0; annot_list && ind < annot_list->Size(); ind++) {
      BlockCFG *annot_cfg = annot_list->At(ind);

      if (annot_cfg->GetAnnotationKind() != AK_Precondition &&
          annot_cfg->GetAnnotationKind() != AK_PreconditionAssume)
        continue;

      Bit *bit = BlockMemory::GetAnnotationBit(annot_cfg);
      if (!bit) continue;

      annot_cfg->IncRef(assume_list);
      bit->IncRef(assume_list);

      AssumeInfo info;
      info.annot = annot_cfg;
      info.bit = bit;
      assume_list->PushBack(info);
    }
  }

  // add assumptions from points within the block.

  for (size_t pind = 0; pind < cfg->GetPointAnnotationCount(); pind++) {
    PointAnnotation pann = cfg->GetPointAnnotation(pind);
    if (end_point && pann.point >= end_point)
      continue;

    BlockCFG *annot_cfg = GetAnnotationCFG(pann.annot);
    if (!annot_cfg) continue;

    Assert(annot_cfg->GetAnnotationKind() != AK_AssertRuntime);

    if (Bit *bit = BlockMemory::GetAnnotationBit(annot_cfg)) {
      // get the annotation bit in terms of block entry.
      Bit *point_bit = NULL;
      mcfg->TranslateBit(TRK_Point, pann.point, bit, &point_bit);
      point_bit->MoveRef(&point_bit, assume_list);

      annot_cfg->IncRef(assume_list);

      AssumeInfo info;
      info.annot = annot_cfg;
      info.point = pann.point;
      info.bit = point_bit;
      assume_list->PushBack(info);
    }

    annot_cfg->DecRef();
  }

  // add assumptions from annotation edges within the block, invariants
  // on values accessed by the block, and from the summaries of any callees.

  for (size_t eind = 0; eind < cfg->GetEdgeCount(); eind++) {
    PEdge *edge = cfg->GetEdge(eind);
    PPoint point = edge->GetSource();

    if (end_point && point >= end_point)
      continue;

    InvariantAssumeVisitor visitor(mcfg, point, assume_list);
    edge->DoVisit(&visitor);

    if (PEdgeAnnotation *nedge = edge->IfAnnotation()) {
      // add an assumption for this annotation.
      BlockCFG *annot_cfg = GetAnnotationCFG(nedge->GetAnnotationId());
      if (!annot_cfg) continue;

      Bit *bit = BlockMemory::GetAnnotationBit(annot_cfg);

//.........这里部分代码省略.........

void TopoSortCFG(BlockCFG *cfg)
{
    // can't topo sort a CFG that might have loops.
    Assert(cfg->GetLoopHeadCount() == 0);

    // map from old CFG points to the new points in the topo order. we can only
    // add a new point once we've added all its predecessors.
    PPointListHash remapping;

    // points in the remappping, in the order to add them to the CFG.
    Vector<Location*> new_points;

    // map from new points back to original CFG points.
    Vector<PPoint> old_points;

    // worklist items are the points where the sources of incoming edges have
    // already been added to the remapping, the point itself has not.
    Vector<PPoint> worklist;

    PPoint entry_point = cfg->GetEntryPoint();
    PPoint exit_point = cfg->GetExitPoint();

    // seed the worklist.
    worklist.PushBack(entry_point);

    while (!worklist.Empty()) {
        // pick the point from the worklist with the minimum line number.
        // if there is code like:
        //   if (x)
        //     a;
        //   else
        //     b;
        // we could add either a or b to the remapping first, but we want to add
        // a first. the ordering of points is used for naming loops, and we want
        // this ordering to be deterministic and map back to the code predictably.

        size_t best_index = 0;
        size_t best_line = cfg->GetPointLocation(worklist[0])->Line();

        for (size_t ind = 1; ind < worklist.Size(); ind++) {
            size_t new_line = cfg->GetPointLocation(worklist[ind])->Line();
            if (new_line < best_line) {
                best_index = ind;
                best_line = new_line;
            }
        }

        PPoint point = worklist[best_index];
        worklist[best_index] = worklist.Back();
        worklist.PopBack();

        Assert(!remapping.Lookup(point, false));

        Location *loc = cfg->GetPointLocation(point);
        loc->IncRef();
        new_points.PushBack(loc);
        old_points.PushBack(point);

        remapping.Insert(point, new_points.Size());

        const Vector<PEdge*> &outgoing = cfg->GetOutgoingEdges(point);
        for (size_t oind = 0; oind < outgoing.Size(); oind++) {
            PEdge *edge = outgoing[oind];
            PPoint target = edge->GetTarget();

            // this can happen if there are multiple edges from the worklist point
            // to the target, e.g. 'if (x) {}'. not going to happen much.
            if (worklist.Contains(target))
                continue;

            Assert(!remapping.Lookup(target, false));

            // we can add the target to the worklist if it has no incoming edges
            // from points not in the remapping.
            bool missing_incoming = false;

            const Vector<PEdge*> &incoming = cfg->GetIncomingEdges(target);
            for (size_t iind = 0; iind < incoming.Size(); iind++) {
                PEdge *edge = incoming[iind];
                PPoint source = edge->GetSource();
                if (!remapping.Lookup(source, false)) {
                    missing_incoming = true;
                    break;
                }
            }

            if (!missing_incoming)
                worklist.PushBack(target);
        }
    }

    // this assert will fail if either the CFG contains cycles, or if there are
    // nodes unreachable from the start. neither of these cases should be
    // possible here.
    Assert(new_points.Size() == cfg->GetPointCount());
    Assert(old_points.Size() == cfg->GetPointCount());

    // remap all the edges. this is also done so that the edges will be
    // in topological order according to their source points.
    Vector<PEdge*> new_edges;
//.........这里部分代码省略.........

void TrimUnreachable(BlockCFG *cfg, bool flatten_skips)
{
    // can't flatten skips if there might be loops in the CFG.
    Assert(!flatten_skips || cfg->GetLoopHeadCount() == 0);

    // receives the locations of the new points and edges of the CFG. we will
    // fill these in, then replace wholesale the old points/edges on the CFG.
    Vector<Location*> new_points;
    Vector<PEdge*> new_edges;
    Vector<LoopHead> new_loop_heads;

    Vector<PPoint> worklist;

    // get the set of points reachable from CFG entry.
    // worklist items are points in entry_reachable whose outgoing edges
    // have not been examined.
    PPointHash entry_reachable;

    PPoint entry = cfg->GetEntryPoint();
    entry_reachable.Insert(entry);
    worklist.PushBack(entry);

    while (!worklist.Empty()) {
        PPoint back = worklist.Back();
        worklist.PopBack();

        const Vector<PEdge*> &outgoing = cfg->GetOutgoingEdges(back);
        for (size_t oind = 0; oind < outgoing.Size(); oind++) {
            PEdge *edge = outgoing[oind];
            PPoint next = edge->GetTarget();

            if (!entry_reachable.Lookup(next)) {
                entry_reachable.Insert(next);
                worklist.PushBack(next);
            }
        }
    }

    // get the set of points which reach the CFG exit.
    // worklist items are points in exit_reaches whose incoming edges
    // have not been examined.
    PPointHash exit_reaches;

    PPoint exit = cfg->GetExitPoint();
    exit_reaches.Insert(exit);
    worklist.PushBack(exit);

    while (!worklist.Empty()) {
        PPoint back = worklist.Back();
        worklist.PopBack();

        const Vector<PEdge*> &incoming = cfg->GetIncomingEdges(back);
        for (size_t iind = 0; iind < incoming.Size(); iind++) {
            PEdge *edge = incoming[iind];
            PPoint prev = edge->GetSource();

            if (!exit_reaches.Lookup(prev)) {
                exit_reaches.Insert(prev);
                worklist.PushBack(prev);
            }
        }
    }

    // make sure we include the entry regardless of whether the function
    // has a path from entry to exit.
    exit_reaches.Insert(entry);
    if (flatten_skips)
        exit_reaches.Insert(FollowSkipEdges(cfg, entry));

    // map from old points to corresponding new points. only defined for
    // points that are in both entry_reachable and exit_reaches,
    // and that do not have outgoing skip edges (if flatten_skips is set).
    PPointListHash remapping;

    // map from some old p0 to another old p1 where p0 connects to p1 by
    // skip edges and p1 has no outgoing skips. empty if flatten_skips is
    // not set. only defined if remapping is defined for p1.
    PPointListHash skip_remapping;

    for (PPoint point = 1; point <= cfg->GetPointCount(); point++) {
        if (entry_reachable.Lookup(point) && exit_reaches.Lookup(point)) {

            // if this is just the source of some skip edges flatten them out.
            // the target of the skips will be defined by remapping since
            // there can be only one outgoing skip edge from a point and
            // thus all paths from point pass through target_point; if point
            // reaches the exit then so does target_point.
            if (flatten_skips) {
                PPoint target_point = FollowSkipEdges(cfg, point);
                if (target_point != point) {
                    skip_remapping.Insert(point, target_point);

                    // don't add anything to remapping for point
                    continue;
                }
            }

            Location *loc = cfg->GetPointLocation(point);
            loc->IncRef();
            new_points.PushBack(loc);
//.........这里部分代码省略.........

// clone a loop body, mapping each point in the body of loophead
// to a new point in receive_cfg. receive_cfg will receive new points
// for the cloned body, and new edges for any non-backedge whose source
// and target are both in loophead's body. for other edges involving loophead,
// old_entry/exit/backedge_indexes will be filled in with indexes into
// the edges list of base_cfg. it may be that base_cfg == receive_cfg.
void CloneLoopBody(BlockCFG *base_cfg, PPoint loophead,
                   PPointListHash *remapping,
                   BlockCFG *receive_cfg,
                   Vector<size_t> *old_entry_indexes,
                   Vector<size_t> *old_exit_indexes,
                   Vector<size_t> *old_back_indexes)
{
    Assert(remapping->IsEmpty());

    Vector<PPoint> *body_list = body_list_table->Lookup(loophead, true);
    Assert(!body_list->Empty());

    // allow for base_cfg == receive_cfg, so keep track of how many points and
    // edges were originally in base_cfg before modifying receive_cfg.
    size_t init_points_size = base_cfg->GetPointCount();
    size_t init_edges_size = base_cfg->GetEdgeCount();

    // copy all points in the loop body to the new CFG.
    for (size_t bind = 0; bind < body_list->Size(); bind++) {
        PPoint body_point = body_list->At(bind);
        Assert(remapping->Lookup(body_point, false) == NULL);

        Assert(0 < body_point && body_point <= init_points_size);
        Location *loc = base_cfg->GetPointLocation(body_point);

        loc->IncRef();
        PPoint new_point = receive_cfg->AddPoint(loc);
        remapping->Insert(body_point, new_point);
    }

    // copy all edges between points in the body to the new CFG.
    for (size_t eind = 0; eind < init_edges_size; eind++) {
        PEdge *edge = base_cfg->GetEdge(eind);
        PPoint source = edge->GetSource();
        PPoint target = edge->GetTarget();

        if (!entry_reach_table->Lookup(source))
            continue;

        PPoint new_source = 0;
        if (body_table->Lookup(PPointPair(loophead, source)))
            new_source = remapping->LookupSingle(source);

        PPoint new_target = 0;
        if (body_table->Lookup(PPointPair(loophead, target)))
            new_target = remapping->LookupSingle(target);

        if (!new_source && !new_target) {
            // edge is not involved with this loop. leave it alone
        }
        else if (!new_source && new_target) {
            // entry edge. leave it alone
            old_entry_indexes->PushBack(eind);
        }
        else if (new_source && !new_target) {
            // exit edge. leave it alone
            old_exit_indexes->PushBack(eind);
        }
        else {
            Assert(new_source && new_target);

            if (target == loophead) {
                // back edge. leave it alone
                Assert(backedge_table->Lookup(edge));
                old_back_indexes->PushBack(eind);
            }
            else {
                // inner edge. clone the edge for the new source and target
                PEdge *new_edge = PEdge::ChangeEdge(edge, new_source, new_target);
                receive_cfg->AddEdge(new_edge);
            }
        }
    }
}

// determine whether loophead is a reducible loop with backedges in cfg.
// fill in dominate_table with the points dominated by loophead,
// and add as backedges any edge going to loophead which is itself
// dominated by loophead. return true if any backedges were found.
bool GetLoopBackedges(BlockCFG *cfg, PPoint loophead)
{
    // compute the nodes reachable from the entry point other than
    // through start. the dominated points are the dual of this set.

    // points reachable from the start according to the above criteria
    PPointHash reachable;

    // worklist items are points in reachable whose outgoing edges have
    // not been examined
    Vector<PPoint> worklist;

    if (!entry_reach_table->Lookup(loophead))
        return false;

    PPoint entry = cfg->GetEntryPoint();
    reachable.Insert(entry);
    worklist.PushBack(entry);

    while (!worklist.Empty()) {
        PPoint back = worklist.Back();
        worklist.PopBack();

        const Vector<PEdge*>& outgoing = cfg->GetOutgoingEdges(back);
        for (size_t oind = 0; oind < outgoing.Size(); oind++) {
            PEdge *edge = outgoing[oind];
            PPoint next = edge->GetTarget();

            if (next == loophead)
                continue;

            // already did this target
            if (reachable.Lookup(next))
                continue;

            reachable.Insert(next);
            worklist.PushBack(next);
        }
    }

    // compute the set of dominated points. this is the difference
    // between the points reachable from the CFG entry, and the points
    // in the reach table we just computed.
    for (PPoint point = 1; point <= cfg->GetPointCount(); point++) {
        if (!reachable.Lookup(point) && entry_reach_table->Lookup(point))
            dominate_table->Insert(PPointPair(loophead, point));
    }

    // backedges on the loophead are incoming edges whose source is
    // dominated by the loophead
    bool found_backedge = false;
    const Vector<PEdge*> &incoming = cfg->GetIncomingEdges(loophead);
    for (size_t eind = 0; eind < incoming.Size(); eind++) {
        PEdge *edge = incoming[eind];
        if (dominate_table->Lookup(PPointPair(loophead, edge->GetSource()))) {
            backedge_table->Insert(edge);
            found_backedge = true;
        }
    }

    return found_backedge;
}

void InferSummaries(const Vector<BlockSummary*> &summary_list)
{
  static BaseTimer infer_timer("infer_summaries");
  Timer _timer(&infer_timer);

  if (summary_list.Empty())
    return;

  Variable *function = summary_list[0]->GetId()->BaseVar();
  Vector<BlockCFG*> *annot_list = BodyAnnotCache.Lookup(function->GetName());

  // all traces which might refer to the result of pointer arithmetic.
  Vector<Exp*> arithmetic_list;
  ArithmeticEscape escape(function, arithmetic_list);

  // initial pass over the CFGs to get traces used in pointer arithmetic.
  for (size_t ind = 0; ind < summary_list.Size(); ind++) {
    BlockSummary *sum = summary_list[ind];

    BlockCFG *cfg = sum->GetMemory()->GetCFG();
    for (size_t eind = 0; eind < cfg->GetEdgeCount(); eind++) {
      PEdge *edge = cfg->GetEdge(eind);

      if (PEdgeAssign *assign_edge = edge->IfAssign()) {
        Exp *left = assign_edge->GetLeftSide();
        Exp *right = assign_edge->GetRightSide();
        ProcessArithmeticAssign(&escape, cfg->GetId(), left, right);
      }
    }
  }

  for (size_t ind = 0; ind < summary_list.Size(); ind++) {
    BlockSummary *sum = summary_list[ind];
    BlockMemory *mcfg = sum->GetMemory();
    BlockCFG *cfg = mcfg->GetCFG();

    // accumulate all the assertions at points in the CFG.
    Vector<AssertInfo> asserts;

    // add assertions at function exit for any postconditions.
    if (cfg->GetId()->Kind() == B_Function) {
      for (size_t aind = 0; annot_list && aind < annot_list->Size(); aind++) {
        BlockCFG *annot_cfg = annot_list->At(aind);

        if (annot_cfg->GetAnnotationKind() != AK_Postcondition)
          continue;
        if (Bit *bit = BlockMemory::GetAnnotationBit(annot_cfg)) {
          AssertInfo info;
          info.kind = ASK_Annotation;
          info.cls = ASC_Check;
          info.point = cfg->GetExitPoint();
          info.bit = bit;
          asserts.PushBack(info);
        }
      }
    }

    // add assertions for any point annotations within the CFG.
    for (size_t pind = 0; pind < cfg->GetPointAnnotationCount(); pind++) {
      PointAnnotation pann = cfg->GetPointAnnotation(pind);
      BlockCFG *annot_cfg = GetAnnotationCFG(pann.annot);
      if (!annot_cfg) continue;

      if (annot_cfg->GetAnnotationKind() != AK_Assert)
        continue;

      if (Bit *bit = BlockMemory::GetAnnotationBit(annot_cfg)) {
        AssertInfo info;
        info.kind = ASK_Annotation;
        info.cls = ASC_Check;
        info.point = pann.point;
        info.bit = bit;
        asserts.PushBack(info);
      }
    }

    for (size_t eind = 0; eind < cfg->GetEdgeCount(); eind++) {
      PEdge *edge = cfg->GetEdge(eind);
      PPoint point = edge->GetSource();

      if (PEdgeAnnotation *nedge = edge->IfAnnotation()) {
        // add an assertion for this annotation if it not an assume.
        BlockCFG *annot_cfg = GetAnnotationCFG(nedge->GetAnnotationId());
        if (!annot_cfg) continue;

        if (annot_cfg->GetAnnotationKind() != AK_Assert &&
            annot_cfg->GetAnnotationKind() != AK_AssertRuntime) {
          continue;
        }

        if (Bit *bit = BlockMemory::GetAnnotationBit(annot_cfg)) {
          AssertInfo info;
          info.kind = (annot_cfg->GetAnnotationKind() == AK_Assert)
            ? ASK_Annotation : ASK_AnnotationRuntime;
          info.cls = ASC_Check;
          info.point = point;
          info.bit = bit;
          asserts.PushBack(info);
        }
      }
//.........这里部分代码省略.........

void BlockModset::ComputeModset(BlockMemory *mcfg, bool indirect)
{
  static BaseTimer compute_timer("modset_compute");
  Timer _timer(&compute_timer);

  // get any indirect callees for this function, provided they have been
  // computed and stored in the callee database (indirect is set).
  CallEdgeSet *indirect_callees = NULL;
  if (indirect)
    indirect_callees = CalleeCache.Lookup(m_id->BaseVar());

  BlockCFG *cfg = mcfg->GetCFG();
  for (size_t eind = 0; eind < cfg->GetEdgeCount(); eind++) {
    PEdge *edge = cfg->GetEdge(eind);
    PPoint point = edge->GetSource();

    if (edge->IsAssign() || edge->IsCall()) {
      // process direct assignments along this edge.

      const Vector<GuardAssign>* assigns = mcfg->GetAssigns(point);
      if (assigns) {
        for (size_t aind = 0; aind < assigns->Size(); aind++) {
          const GuardAssign &gasn = assigns->At(aind);
          ProcessUpdatedLval(mcfg, gasn.left, NULL, true, false);

          Exp *use_lval = NULL;
          Exp *kind = mcfg->GetTerminateAssign(point, gasn.left, gasn.right,
                                               &use_lval);
          if (kind) {
            ProcessUpdatedLval(mcfg, use_lval, kind, false, false);
            kind->DecRef();
          }
        }
      }
    }

    // pull in modsets from the direct and indirect callees of the edge.
    if (BlockId *callee = edge->GetDirectCallee()) {
      ComputeModsetCall(mcfg, edge, callee, NULL);
      callee->DecRef();
    }
    else if (edge->IsCall() && indirect_callees) {
      for (size_t ind = 0; ind < indirect_callees->GetEdgeCount(); ind++) {
        const CallEdge &cedge = indirect_callees->GetEdge(ind);

        // when comparing watch out for the case that this is a temporary
        // modset and does not share the same block kind as the edge point.
        if (cedge.where.version == cfg->GetVersion() &&
            cedge.where.point == point &&
            cedge.where.id->Function() == m_id->Function() &&
            cedge.where.id->Loop() == m_id->Loop()) {
          cedge.callee->IncRef();
          BlockId *callee = BlockId::Make(B_Function, cedge.callee);

          ComputeModsetCall(mcfg, edge, callee, cedge.rfld_chain);
          callee->DecRef();
        }
      }
    }
  }

  // sort the modset exps to ensure a consistent representation.
  if (m_modset_list)
    SortVector<PointValue,compare_PointValue>(m_modset_list);
  if (m_assign_list)
    SortVector<GuardAssign,compare_GuardAssign>(m_assign_list);

  if (indirect)
    CalleeCache.Release(m_id->BaseVar());
}