private void enqueueParents(final SSAConstructionInfo consInfo) {
		final Set seen = new HashSet();

		final Iterator iter = cfg.nodes().iterator();

		while (iter.hasNext()) {
			final Block block = (Block) iter.next();

			final Iterator e = consInfo.realsAtBlock(block).iterator();

			while (e.hasNext()) {
				final VarExpr real = (VarExpr) e.next();

				Node p = real.parent();

				if ((p instanceof StoreExpr) && real.isDef()) {
					p = p.parent();
				}

				if ((p instanceof Expr) && !seen.contains(p)) {
					final Expr expr = (Expr) p;

					seen.add(p);

					if (isFirstOrder(expr)) {
						worklist.addReal(expr);
					}
				}
			}
		}
	}