C++ ProgramPoint::getTag方法代码示例

bool ExplodedGraph::shouldCollect(const ExplodedNode *node) {
  // First, we only consider nodes for reclamation of the following
  // conditions apply:
  //
  // (1) 1 predecessor (that has one successor)
  // (2) 1 successor (that has one predecessor)
  //
  // If a node has no successor it is on the "frontier", while a node
  // with no predecessor is a root.
  //
  // After these prerequisites, we discard all "filler" nodes that
  // are used only for intermediate processing, and are not essential
  // for analyzer history:
  //
  // (a) PreStmtPurgeDeadSymbols
  //
  // We then discard all other nodes where *all* of the following conditions
  // apply:
  //
  // (3) The ProgramPoint is for a PostStmt, but not a PostStore.
  // (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) Expressions that are *not* lvalue expressions.
  // (9) The PostStmt isn't for a non-consumed Stmt or Expr.
  // (10) The successor is neither a CallExpr StmtPoint nor a CallEnter or 
  //      PreImplicitCall (so that we would be able to find it when retrying a 
  //      call with no inlining).
  // FIXME: It may be safe to reclaim PreCall and PostCall nodes as well.

  // Conditions 1 and 2.
  if (node->pred_size() != 1 || node->succ_size() != 1)
    return false;

  const ExplodedNode *pred = *(node->pred_begin());
  if (pred->succ_size() != 1)
    return false;
  
  const ExplodedNode *succ = *(node->succ_begin());
  if (succ->pred_size() != 1)
    return false;

  // Now reclaim any nodes that are (by definition) not essential to
  // analysis history and are not consulted by any client code.
  ProgramPoint progPoint = node->getLocation();
  if (progPoint.getAs<PreStmtPurgeDeadSymbols>())
    return !progPoint.getTag();

  // Condition 3.
  if (!progPoint.getAs<PostStmt>() || progPoint.getAs<PostStore>())
    return false;

  // Condition 4.
  if (progPoint.getTag())
    return false;

  // Conditions 5, 6, and 7.
  ProgramStateRef state = node->getState();
  ProgramStateRef pred_state = pred->getState();    
  if (state->store != pred_state->store || state->GDM != pred_state->GDM ||
      progPoint.getLocationContext() != pred->getLocationContext())
    return false;

  // All further checks require expressions. As per #3, we know that we have
  // a PostStmt.
  const Expr *Ex = dyn_cast<Expr>(progPoint.castAs<PostStmt>().getStmt());
  if (!Ex)
    return false;

  // Condition 8.
  // Do not collect nodes for "interesting" lvalue expressions since they are
  // used extensively for generating path diagnostics.
  if (isInterestingLValueExpr(Ex))
    return false;

  // Condition 9.
  // Do not collect nodes for non-consumed Stmt or Expr to ensure precise
  // diagnostic generation; specifically, so that we could anchor arrows
  // pointing to the beginning of statements (as written in code).
  ParentMap &PM = progPoint.getLocationContext()->getParentMap();
  if (!PM.isConsumedExpr(Ex))
    return false;

  // Condition 10.
  const ProgramPoint SuccLoc = succ->getLocation();
  if (Optional<StmtPoint> SP = SuccLoc.getAs<StmtPoint>())
    if (CallEvent::isCallStmt(SP->getStmt()))
      return false;

  // Condition 10, continuation.
  if (SuccLoc.getAs<CallEnter>() || SuccLoc.getAs<PreImplicitCall>())
    return false;

  return true;
}