Merge pull request #1542 from YosysHQ/dave/abc9-loop-fix

abc9: Fix breaking of SCCs

2 files changed, 46 insertions, 29 deletions

diff --git a/passes/techmap/abc9.cc b/passes/techmap/abc9.cc
index 27106cc5d..8276c3c16 100644
--- a/passes/techmap/abc9.cc
+++ b/passes/techmap/abc9.cc
@@ -94,20 +94,30 @@ void handle_loops(RTLIL::Design *design)
 					if (cell->output(c.first)) {
 						SigBit b = c.second.as_bit();
 						Wire *w = b.wire;
-						log_assert(!w->port_input);
-						w->port_input = true;
-						w = module->wire(stringf("%s.abci", w->name.c_str()));
-						if (!w) {
-							w = module->addWire(stringf("%s.abci", b.wire->name.c_str()), GetSize(b.wire));
-							w->port_output = true;
+						if (w->port_input) {
+							// In this case, hopefully the loop break has been already created
+							// Get the non-prefixed wire
+							Wire *wo = module->wire(stringf("%s.abco", b.wire->name.c_str()));
+							log_assert(wo != nullptr);
+							log_assert(wo->port_output);
+							log_assert(b.offset < GetSize(wo));
+							c.second = RTLIL::SigBit(wo, b.offset);
 						}
 						else {
-							log_assert(w->port_input);
-							log_assert(b.offset < GetSize(w));
+							// Create a new output/input loop break
+							w->port_input = true;
+							w = module->wire(stringf("%s.abco", w->name.c_str()));
+							if (!w) {
+								w = module->addWire(stringf("%s.abco", b.wire->name.c_str()), GetSize(b.wire));
+								w->port_output = true;
+							}
+							else {
+								log_assert(w->port_input);
+								log_assert(b.offset < GetSize(w));
+							}
+							w->set_bool_attribute(ID(abc9_scc_break));
+							c.second = RTLIL::SigBit(w, b.offset);
 						}
-						w->set_bool_attribute(ID(abc9_scc_break));
-						module->swap_names(b.wire, w);
-						c.second = RTLIL::SigBit(w, b.offset);
 					}
 				}
 			}
@@ -420,24 +430,6 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
 
 		design->selection_stack.pop_back();
 
-		// Now 'unexpose' those wires by undoing
-		// the expose operation -- remove them from PO/PI
-		// and re-connecting them back together
-		for (auto wire : module->wires()) {
-			auto it = wire->attributes.find(ID(abc9_scc_break));
-			if (it != wire->attributes.end()) {
-				wire->attributes.erase(it);
-				log_assert(wire->port_output);
-				wire->port_output = false;
-				RTLIL::Wire *i_wire = module->wire(wire->name.str() + ".abci");
-				log_assert(i_wire);
-				log_assert(i_wire->port_input);
-				i_wire->port_input = false;
-				module->connect(i_wire, wire);
-			}
-		}
-		module->fixup_ports();
-
 		log_header(design, "Executing ABC9.\n");
 
 		if (!lut_costs.empty()) {
@@ -781,6 +773,25 @@ clone_lut:
 			}
 		}
 
+		// Now 'unexpose' those wires by undoing
+		// the expose operation -- remove them from PO/PI
+		// and re-connecting them back together
+		for (auto wire : module->wires()) {
+			auto it = wire->attributes.find(ID(abc9_scc_break));
+			if (it != wire->attributes.end()) {
+				wire->attributes.erase(it);
+				log_assert(wire->port_output);
+				wire->port_output = false;
+				std::string name = wire->name.str();
+				RTLIL::Wire *i_wire = module->wire(name.substr(0, GetSize(name) - 5));
+				log_assert(i_wire);
+				log_assert(i_wire->port_input);
+				i_wire->port_input = false;
+				module->connect(i_wire, wire);
+			}
+		}
+		module->fixup_ports();
+
 		//log("ABC RESULTS:        internal signals: %8d\n", int(signal_list.size()) - in_wires - out_wires);
 		log("ABC RESULTS:           input signals: %8d\n", in_wires);
 		log("ABC RESULTS:          output signals: %8d\n", out_wires);
diff --git a/tests/simple_abc9/abc9.v b/tests/simple_abc9/abc9.v
index 4d5879e6f..de60619d1 100644
--- a/tests/simple_abc9/abc9.v
+++ b/tests/simple_abc9/abc9.v
@@ -258,3 +258,9 @@ module abc9_test026(output [3:0] o, p);
 assign o = { 1'b1, 1'bx };
 assign p = { 1'b1, 1'bx, 1'b0 };
 endmodule
+
+module abc9_test030(input [3:0] d, input en, output reg [3:0] q);
+always @*
+  if (en)
+    q <= d;
+endmodule