sta: very crude static timing analysis pass

Co-authored-by: Eddie Hung <eddie@fpgeh.com>

1 files changed, 28 insertions, 30 deletions

diff --git a/passes/techmap/abc9_ops.cc b/passes/techmap/abc9_ops.cc
index 7a6959971..29fe74ec7 100644
--- a/passes/techmap/abc9_ops.cc
+++ b/passes/techmap/abc9_ops.cc
@@ -648,40 +648,38 @@ void prep_delays(RTLIL::Design *design, bool dff_mode)
 		auto inst_module = design->module(cell->type);
 		log_assert(inst_module);
 
-		auto &t = timing.at(cell->type).required;
-		for (auto &conn : cell->connections_) {
-			auto port_wire = inst_module->wire(conn.first);
+		for (auto &i : timing.at(cell->type).required) {
+			auto port_wire = inst_module->wire(i.first.name);
 			if (!port_wire)
 				log_error("Port %s in cell %s (type %s) from module %s does not actually exist",
-						log_id(conn.first), log_id(cell), log_id(cell->type), log_id(module));
-			if (!port_wire->port_input)
-				continue;
-			if (conn.second.is_fully_const())
+						log_id(i.first.name), log_id(cell), log_id(cell->type), log_id(module));
+			log_assert(port_wire->port_input);
+
+			auto d = i.second.first;
+			if (d == 0)
 				continue;
 
-			SigSpec O = module->addWire(NEW_ID, GetSize(conn.second));
-			for (int i = 0; i < GetSize(conn.second); i++) {
-				auto d = t.at(TimingInfo::NameBit(conn.first,i), 0);
-				if (d == 0)
-					continue;
+			auto offset = i.first.offset;
+			auto O = module->addWire(NEW_ID);
+			auto rhs = cell->getPort(i.first.name);
 
 #ifndef NDEBUG
-				if (ys_debug(1)) {
-					static std::set<std::tuple<IdString,IdString,int>> seen;
-					if (seen.emplace(cell->type, conn.first, i).second) log("%s.%s[%d] abc9_required = %d\n",
-							log_id(cell->type), log_id(conn.first), i, d);
-				}
+			if (ys_debug(1)) {
+				static pool<std::pair<IdString,TimingInfo::NameBit>> seen;
+				if (seen.emplace(cell->type, i.first).second) log("%s.%s[%d] abc9_required = %d\n",
+						log_id(cell->type), log_id(i.first.name), offset, d);
+			}
 #endif
-				auto r = box_cache.insert(d);
-				if (r.second) {
-					r.first->second = delay_module->derive(design, {{ID::DELAY, d}});
-					log_assert(r.first->second.begins_with("$paramod$__ABC9_DELAY\\DELAY="));
-				}
-				auto box = module->addCell(NEW_ID, r.first->second);
-				box->setPort(ID::I, conn.second[i]);
-				box->setPort(ID::O, O[i]);
-				conn.second[i] = O[i];
+			auto r = box_cache.insert(d);
+			if (r.second) {
+				r.first->second = delay_module->derive(design, {{ID::DELAY, d}});
+				log_assert(r.first->second.begins_with("$paramod$__ABC9_DELAY\\DELAY="));
 			}
+			auto box = module->addCell(NEW_ID, r.first->second);
+			box->setPort(ID::I, rhs[offset]);
+			box->setPort(ID::O, O);
+			rhs[offset] = O;
+			cell->setPort(i.first.name, rhs);
 		}
 	}
 }
@@ -1006,16 +1004,16 @@ void prep_box(RTLIL::Design *design)
 				log_assert(GetSize(wire) == 1);
 				auto it = t.find(TimingInfo::NameBit(port_name,0));
 				if (it == t.end())
-					// Assume no connectivity if no setup time
-					ss << "-";
+					// Assume that no setup time means zero
+					ss << 0;
 				else {
-					ss << it->second;
+					ss << it->second.first;
 
 #ifndef NDEBUG
 					if (ys_debug(1)) {
 						static std::set<std::pair<IdString,IdString>> seen;
 						if (seen.emplace(module->name, port_name).second) log("%s.%s abc9_required = %d\n", log_id(module),
-								log_id(port_name), it->second);
+								log_id(port_name), it->second.first);
 					}
 #endif
 				}