cxxrtl: Prevent wires with input or output ports from being aliased

Author: noeamiot

backends/cxxrtl/cxxrtl_backend.cc

@@ -3263,6 +3263,7 @@ struct CxxrtlWorker {
 						debug_wire_type = wire_type; // wire is a member
 
 					if (!debug_alias) continue;
+					if (wire->port_input || wire->port_output) continue; // preserve input/output metadata in flags
 					const RTLIL::Wire *it = wire;
 					while (flow.is_inlinable(it)) {
 						log_assert(flow.wire_comb_defs[it].size() == 1);