Ejemplo n.º 1
0
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);

      // don't incorporate AssertRuntimes, these are not assumed.
      if (bit && annot_cfg->GetAnnotationKind() != AK_AssertRuntime) {
        // get the annotation bit in terms of block entry.
        Bit *point_bit = NULL;
        mcfg->TranslateBit(TRK_Point, point, bit, &point_bit);
        point_bit->MoveRef(&point_bit, assume_list);

        annot_cfg->IncRef(assume_list);

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

      annot_cfg->DecRef();
    }

    if (BlockId *callee = edge->GetDirectCallee()) {
      GetCallAssumedBits(mcfg, edge, callee, false, assume_list);
      callee->DecRef();
    }
    else if (edge->IsCall()) {
      // add conditional assumes for the indirect targets of the call.
      // this is most useful for baked information and annotations, where
      // we sometimes need to attach information at indirect calls.

      CallEdgeSet *callees = CalleeCache.Lookup(id->BaseVar());
      size_t old_count = assume_list->Size();

      if (callees) {
        for (size_t cind = 0; cind < callees->GetEdgeCount(); cind++) {
          const CallEdge &cedge = callees->GetEdge(cind);
          if (cedge.where.id == id && cedge.where.point == point) {
            cedge.callee->IncRef();
            BlockId *callee = BlockId::Make(B_Function, cedge.callee);

            GetCallAssumedBits(mcfg, edge, callee, true, assume_list);
            callee->DecRef();
          }
        }
      }

      if (assume_list->Size() != old_count) {
        // we managed to do something at this indirect call site.
        // add another assumption restricting the possible callees to
        // only those identified by our callgraph.

        GuardExpVector receiver_list;
        mcfg->TranslateReceiver(point, &receiver_list);

        for (size_t rind = 0; rind < receiver_list.Size(); rind++) {
          const GuardExp &gs = receiver_list[rind];
          gs.guard->IncRef();

          // make a bit: !when || rcv == callee0 || rcv == callee1 || ...
          Bit *extra_bit = Bit::MakeNot(gs.guard);

          for (size_t cind = 0; cind < callees->GetEdgeCount(); cind++) {
            const CallEdge &cedge = callees->GetEdge(cind);
            if (cedge.where.id == id && cedge.where.point == point) {
              Variable *callee_var = cedge.callee;
              callee_var->IncRef();
              Exp *callee_exp = Exp::MakeVar(callee_var);

              gs.exp->IncRef();
              Bit *equal = Exp::MakeCompareBit(B_Equal, callee_exp, gs.exp);

              extra_bit = Bit::MakeOr(extra_bit, equal);
            }
          }

          extra_bit->MoveRef(NULL, assume_list);

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

      CalleeCache.Release(id->BaseVar());
    }
  }

  BodyAnnotCache.Release(id->Function());

  // add assumptions from heap invariants describing values mentioned
  // in added assumptions. we could keep doing this transitively but don't,
  // to ensure termination.
  size_t count = assume_list->Size();
  for (size_t ind = 0; ind < count; ind++) {
    InvariantAssumeVisitor visitor(NULL, 0, assume_list);
    assume_list->At(ind).bit->DoVisit(&visitor);
  }

  CombineAssumeList(assume_list);
}
Ejemplo n.º 2
0
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());
}