More meaningful error message

diff --git a/passes/techmap/abc9.cc b/passes/techmap/abc9.cc
index c8272153d58359e961385a04b30da68db8e2555f..6356d4fbf0d0e1b83dfbffa385766de4034e0d77 100644 (file)
--- a/passes/techmap/abc9.cc
+++ b/passes/techmap/abc9.cc
@@ -118,6 +118,8 @@ void handle_loops(RTLIL::Design *design)
                        auto jt = box_module->attributes.find("\\abc_scc_break");
                        if (jt != box_module->attributes.end()) {
                                auto it = cell->connections_.find(RTLIL::escape_id(jt->second.decode_string()));
+                               if (it == cell->connections_.end())
+                                       log_error("abc_scc_break attribute value '%s' does not exist as port on module '%s'\n", jt->second.decode_string().c_str(), log_id(box_module));
                                log_assert(it != cell->connections_.end());
                                auto &c = *it;
                                SigBit b = cell->getPort(RTLIL::escape_id(jt->second.decode_string()));