Merge pull request #1573 from YosysHQ/eddie/xilinx_tristate

synth_xilinx: error out if tristate without '-iopad'

passes/techmap/tribuf.cc

@@ -86,6 +86,7 @@ struct TribufWorker {
 					cell->unsetPort(ID(S));
 					cell->type = tri_type;
 					tribuf_cells[sigmap(cell->getPort(ID::Y))].push_back(cell);
+					module->design->scratchpad_set_bool("tribuf.added_something", true);
 					continue;
 				}
 
@@ -95,6 +96,7 @@ struct TribufWorker {
 					cell->unsetPort(ID(S));
 					cell->type = tri_type;
 					tribuf_cells[sigmap(cell->getPort(ID::Y))].push_back(cell);
+					module->design->scratchpad_set_bool("tribuf.added_something", true);
 					continue;
 				}
 			}
@@ -130,8 +132,10 @@ struct TribufWorker {
 
 				if (no_tribuf)
 					module->connect(it.first, muxout);
-				else
+				else {
 					module->addTribuf(NEW_ID, muxout, module->ReduceOr(NEW_ID, pmux_s), it.first);
+					module->design->scratchpad_set_bool("tribuf.added_something", true);
+				}
 			}
 		}
 	}

techlibs/xilinx/synth_xilinx.cc

@@ -316,7 +316,10 @@ struct SynthXilinxPass : public ScriptPass
 			run("proc");
 			if (flatten || help_mode)
 				run("flatten", "(with '-flatten')");
+			active_design->scratchpad_unset("tribuf.added_something");
 			run("tribuf -logic");
+			if (!do_iopad && active_design->scratchpad_get_bool("tribuf.added_something"))
+				log_error("Tristate buffers are unsupported without the '-iopad' option.\n");
 			run("deminout");
 			run("opt_expr");
 			run("opt_clean");

tests/arch/xilinx/tribuf.sh

@@ -0,0 +1,5 @@
+! ../../../yosys ../common/tribuf.v -qp "synth_xilinx"
+../../../yosys ../common/tribuf.v -qp "synth_xilinx -iopad; \
+select -assert-count 2 t:IBUF; \
+select -assert-count 1 t:INV; \
+select -assert-count 1 t:OBUFT"