1 files changed, 38 insertions, 16 deletions

diff --git a/backends/aiger/xaiger.cc b/backends/aiger/xaiger.cc
index 8a35e06fa..19e6c8369 100644
--- a/backends/aiger/xaiger.cc
+++ b/backends/aiger/xaiger.cc
@@ -211,6 +211,7 @@ struct XAigerWriter
 		//       box ordering, but not individual AIG cells
 		dict<SigBit, pool<IdString>> bit_drivers, bit_users;
 		TopoSort<IdString, RTLIL::sort_by_id_str> toposort;
+		dict<IdString, std::pair<IdString,IdString>> flop_data;
 		bool abc_box_seen = false;
 
 		for (auto cell : module->selected_cells()) {
@@ -264,36 +265,57 @@ struct XAigerWriter
 				abc_box_seen = true;
 
 				toposort.node(cell->name);
-				auto abc_flop_d = inst_module->attributes.at("\\abc_flop_d", RTLIL::Const());
-				if (abc_flop_d.size() == 0) {
-					for (const auto &conn : cell->connections()) {
-						if (cell->input(conn.first)) {
-							// Ignore inout for the sake of topographical ordering
-							if (cell->output(conn.first)) continue;
-							for (auto bit : sigmap(conn.second))
-								bit_users[bit].insert(cell->name);
-						}
 
-						if (cell->output(conn.first))
-							for (auto bit : sigmap(conn.second))
-								bit_drivers[bit].insert(cell->name);
+				auto r = flop_data.insert(std::make_pair(cell->type, std::make_pair(IdString(), IdString())));
+				if (r.second) {
+					auto it = inst_module->attributes.find("\\abc_flop");
+					if (it != inst_module->attributes.end()) {
+						std::string abc_flop = it->second.decode_string();
+						size_t start, end;
+						end = abc_flop.find(','); // Ignore original module
+						log_assert(end != std::string::npos);
+						start = end + 1;
+						end = abc_flop.find(',', start + 1);
+						log_assert(start != std::string::npos && end != std::string::npos);
+						auto abc_flop_d = RTLIL::escape_id(abc_flop.substr(start, end-start));
+						start = end + 1;
+						end = abc_flop.find(',', start + 1);
+						log_assert(start != std::string::npos && end != std::string::npos);
+						auto abc_flop_q = RTLIL::escape_id(abc_flop.substr(start, end-start));
+						r.first->second = std::make_pair(abc_flop_d, abc_flop_q);
 					}
 				}
-				else {
-					auto abc_flop_q = inst_module->attributes.at("\\abc_flop_q");
 
-					SigBit d = cell->getPort(RTLIL::escape_id(abc_flop_d.decode_string()));
+				auto abc_flop_d = r.first->second.first;
+				if (abc_flop_d != IdString()) {
+					SigBit d = cell->getPort(abc_flop_d);
 					SigBit I = sigmap(d);
 					if (I != d)
 						alias_map[I] = d;
 					unused_bits.erase(d);
 
-					SigBit q = cell->getPort(RTLIL::escape_id(abc_flop_q.decode_string()));
+					auto abc_flop_q = r.first->second.second;
+					SigBit q = cell->getPort(abc_flop_q);
 					SigBit O = sigmap(q);
 					if (O != q)
 						alias_map[O] = q;
 					undriven_bits.erase(O);
 					ff_bits.emplace_back(q);
+
+				}
+				else {
+					for (const auto &conn : cell->connections()) {
+						if (cell->input(conn.first)) {
+							// Ignore inout for the sake of topographical ordering
+							if (cell->output(conn.first)) continue;
+							for (auto bit : sigmap(conn.second))
+								bit_users[bit].insert(cell->name);
+						}
+
+						if (cell->output(conn.first))
+							for (auto bit : sigmap(conn.second))
+								bit_drivers[bit].insert(cell->name);
+					}
 				}
 			}
 			else {