xaiger: remove some unnecessary operations ...

... since they can not be triggered by (* keep *) anymore
(but could still be triggered by (* abc9_scc *) !?!)

diff --git a/backends/aiger/xaiger.cc b/backends/aiger/xaiger.cc
index 7b6b851b36b591a4a7732d4ce395feca7f172dfc..cde6d066ac9de3dfa1fd7eac9c022b4190f0eae0 100644 (file)
--- a/backends/aiger/xaiger.cc
+++ b/backends/aiger/xaiger.cc
@@ -224,8 +224,6 @@ struct XAigerWriter
                                        alias_map[Q] = D;
                                        auto r YS_ATTRIBUTE(unused) = ff_bits.insert(std::make_pair(D, cell));
                                        log_assert(r.second);
-                                       if (input_bits.erase(Q))
-                                               log_assert(Q.wire->attributes.count(ID::keep));
                                        continue;
                                }
 
@@ -379,11 +377,6 @@ struct XAigerWriter
                                                        alias_map[O] = b;
                                                ci_bits.emplace_back(b);
                                                undriven_bits.erase(O);
-                                               // If PI and CI, then must be a (* keep *) wire
-                                               if (input_bits.erase(O)) {
-                                                       log_assert(output_bits.count(O));
-                                                       log_assert(O.wire->get_bool_attribute(ID::keep));
-                                               }
                                        }
                        }
 
@@ -468,8 +461,8 @@ struct XAigerWriter
                for (const auto &bit : output_bits) {
                        ordered_outputs[bit] = aig_o++;
                        int aig;
-                       // Unlike bit2aig() which checks aig_map first, for
-                       //   inout/keep bits, since aig_map will point to
+                       // Unlike bit2aig() which checks aig_map first for
+                       //   inout/scc bits, since aig_map will point to
                        //   the PI, first attempt to find the NOT/AND driver
                        //   before resorting to an aig_map lookup (which
                        //   could be another PO)