Merge pull request #1188 from YosysHQ/eddie/abc9_push_inverters

abc9: push inverters driving box inputs (comb outputs) through $lut soft logic

passes/techmap/abc9.cc

@@ -24,12 +24,13 @@
 
 #if 0
 // Based on &flow3 - better QoR but more experimental
-#define ABC_COMMAND_LUT "&st; &ps -l; "/*"&sweep -v;"*/" &scorr; " \
+#define ABC_COMMAND_LUT "&st; &ps -l; &sweep -v; &scorr; " \
-						"&st; &if {W}; &save; &st; &syn2; &if {W}; &save; &load; "\
+						"&st; &if {W}; &save; &st; &syn2; &if {W} -v; &save; &load; "\
-						"&st; &if -g -K 6; &dch -f; &if {W}; &save; &load; "\
+						"&st; &if -g -K 6; &dch -f; &if {W} -v; &save; &load; "\
-						"&st; &if -g -K 6; &synch2; &if {W}; &save; &load"
+						"&st; &if -g -K 6; &synch2; &if {W} -v; &save; &load; "\
+						"&mfs; &ps -l"
 #else
-#define ABC_COMMAND_LUT "&st; &scorr; &sweep; &dc2; &st; &dch -f; &ps -l; &if {W} {D} -v; &mfs; &ps -l"
+#define ABC_COMMAND_LUT "&st; &scorr; &sweep; &dc2; &st; &dch -f; &ps; &if {W} {D} -v; &mfs; &ps -l"
 #endif
 
 
@@ -53,6 +54,7 @@
 #endif
 
 #include "frontends/aiger/aigerparse.h"
+#include "kernel/utils.h"
 
 #ifdef YOSYS_LINK_ABC
 extern "C" int Abc_RealMain(int argc, char *argv[]);
@@ -570,13 +572,23 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
 				boxes.emplace_back(cell);
 		}
 
+		dict<SigBit, pool<IdString>> bit_drivers, bit_users;
+		TopoSort<IdString, RTLIL::sort_by_id_str> toposort;
+		dict<RTLIL::Cell*,RTLIL::Cell*> not2drivers;
+		dict<SigBit, std::vector<RTLIL::Cell*>> bit2sinks;
+
 		std::map<std::string, int> cell_stats;
 		for (auto c : mapped_mod->cells())
 		{
+			toposort.node(c->name);
+
 			RTLIL::Cell *cell = nullptr;
 			if (c->type == "$_NOT_") {
-				RTLIL::SigBit a_bit = c->getPort("\\A").as_bit();
+				RTLIL::SigBit a_bit = c->getPort("\\A");
-				RTLIL::SigBit y_bit = c->getPort("\\Y").as_bit();
+				RTLIL::SigBit y_bit = c->getPort("\\Y");
+				bit_users[a_bit].insert(c->name);
+				bit_drivers[y_bit].insert(c->name);
+
 				if (!a_bit.wire) {
 					c->setPort("\\Y", module->addWire(NEW_ID));
 					RTLIL::Wire *wire = module->wire(remap_name(y_bit.wire->name));
@@ -584,11 +596,11 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
 					module->connect(RTLIL::SigBit(wire, y_bit.offset), RTLIL::S1);
 				}
 				else if (!lut_costs.empty() || !lut_file.empty()) {
-					RTLIL::Cell* driving_lut = nullptr;
+					RTLIL::Cell* driver_lut = nullptr;
 					// ABC can return NOT gates that drive POs
 					if (!a_bit.wire->port_input) {
 						// If it's not a NOT gate that that comes from a PI directly,
-						// find the driving LUT and clone that to guarantee that we won't
+						// find the driver LUT and clone that to guarantee that we won't
 						// increase the max logic depth
 						// (TODO: Optimise by not cloning unless will increase depth)
 						RTLIL::IdString driver_name;
@@ -596,38 +608,25 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
 							driver_name = stringf("%s$lut", a_bit.wire->name.c_str());
 						else
 							driver_name = stringf("%s[%d]$lut", a_bit.wire->name.c_str(), a_bit.offset);
-						driving_lut = mapped_mod->cell(driver_name);
+						driver_lut = mapped_mod->cell(driver_name);
 					}
 
-					if (!driving_lut) {
+					if (!driver_lut) {
-						// If a driver couldn't be found (could be from PI,
+						// If a driver couldn't be found (could be from PI or box CI)
-						// or from a box) then implement using a LUT
+						// then implement using a LUT
 						cell = module->addLut(remap_name(stringf("%s$lut", c->name.c_str())),
-								RTLIL::SigBit(module->wires_[remap_name(a_bit.wire->name)], a_bit.offset),
+								RTLIL::SigBit(module->wires_.at(remap_name(a_bit.wire->name)), a_bit.offset),
-								RTLIL::SigBit(module->wires_[remap_name(y_bit.wire->name)], y_bit.offset),
+								RTLIL::SigBit(module->wires_.at(remap_name(y_bit.wire->name)), y_bit.offset),
-								1);
+								RTLIL::Const::from_string("01"));
+						bit2sinks[cell->getPort("\\A")].push_back(cell);
+						cell_stats["$lut"]++;
 					}
-					else {
+					else
-						auto driver_a = driving_lut->getPort("\\A").chunks();
+						not2drivers[c] = driver_lut;
-						for (auto &chunk : driver_a)
+					continue;
-							chunk.wire = module->wires_[remap_name(chunk.wire->name)];
-						RTLIL::Const driver_lut = driving_lut->getParam("\\LUT");
-						for (auto &b : driver_lut.bits) {
-							if (b == RTLIL::State::S0) b = RTLIL::State::S1;
-							else if (b == RTLIL::State::S1) b = RTLIL::State::S0;
-						}
-						cell = module->addLut(remap_name(stringf("%s$lut", c->name.c_str())),
-								driver_a,
-								RTLIL::SigBit(module->wires_[remap_name(y_bit.wire->name)], y_bit.offset),
-								driver_lut);
-					}
-				}
-				else {
-					cell = module->addCell(remap_name(c->name), "$_NOT_");
-					cell->setPort("\\A", RTLIL::SigBit(module->wires_[remap_name(a_bit.wire->name)], a_bit.offset));
-					cell->setPort("\\Y", RTLIL::SigBit(module->wires_[remap_name(y_bit.wire->name)], y_bit.offset));
-					cell_stats[RTLIL::unescape_id(c->type)]++;
 				}
+				else
+					log_abort();
 				if (cell && markgroups) cell->attributes["\\abcgroup"] = map_autoidx;
 				continue;
 			}
@@ -635,11 +634,12 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
 
 			RTLIL::Cell *existing_cell = nullptr;
 			if (c->type == "$lut") {
-				if (GetSize(c->getPort("\\A")) == 1 && c->getParam("\\LUT").as_int() == 2) {
+				if (GetSize(c->getPort("\\A")) == 1 && c->getParam("\\LUT") == RTLIL::Const::from_string("01")) {
-					SigSpec my_a = module->wires_[remap_name(c->getPort("\\A").as_wire()->name)];
+					SigSpec my_a = module->wires_.at(remap_name(c->getPort("\\A").as_wire()->name));
-					SigSpec my_y = module->wires_[remap_name(c->getPort("\\Y").as_wire()->name)];
+					SigSpec my_y = module->wires_.at(remap_name(c->getPort("\\Y").as_wire()->name));
 					module->connect(my_y, my_a);
 					if (markgroups) c->attributes["\\abcgroup"] = map_autoidx;
+					log_abort();
 					continue;
 				}
 				cell = module->addCell(remap_name(c->name), c->type);
@@ -666,10 +666,20 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
 						continue;
 					//log_assert(c.width == 1);
 					if (c.wire)
-						c.wire = module->wires_[remap_name(c.wire->name)];
+						c.wire = module->wires_.at(remap_name(c.wire->name));
 					newsig.append(c);
 				}
 				cell->setPort(conn.first, newsig);
+
+				if (cell->input(conn.first)) {
+					for (auto i : newsig)
+						bit2sinks[i].push_back(cell);
+					for (auto i : conn.second)
+						bit_users[i].insert(c->name);
+				}
+				if (cell->output(conn.first))
+					for (auto i : conn.second)
+						bit_drivers[i].insert(c->name);
 			}
 		}
 
@@ -681,14 +691,14 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
 			if (!conn.first.is_fully_const()) {
 				auto chunks = conn.first.chunks();
 				for (auto &c : chunks)
-					c.wire = module->wires_[remap_name(c.wire->name)];
+					c.wire = module->wires_.at(remap_name(c.wire->name));
 				conn.first = std::move(chunks);
 			}
 			if (!conn.second.is_fully_const()) {
 				auto chunks = conn.second.chunks();
 				for (auto &c : chunks)
 					if (c.wire)
-						c.wire = module->wires_[remap_name(c.wire->name)];
+						c.wire = module->wires_.at(remap_name(c.wire->name));
 				conn.second = std::move(chunks);
 			}
 			module->connect(conn);
@@ -725,6 +735,79 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
 			}
 		}
 
+		for (auto &it : bit_users)
+			if (bit_drivers.count(it.first))
+				for (auto driver_cell : bit_drivers.at(it.first))
+				for (auto user_cell : it.second)
+					toposort.edge(driver_cell, user_cell);
+		bool no_loops = toposort.sort();
+		log_assert(no_loops);
+
+		for (auto ii = toposort.sorted.rbegin(); ii != toposort.sorted.rend(); ii++) {
+			RTLIL::Cell *not_cell = mapped_mod->cell(*ii);
+			log_assert(not_cell);
+			if (not_cell->type != "$_NOT_")
+				continue;
+			auto it = not2drivers.find(not_cell);
+			if (it == not2drivers.end())
+				continue;
+			RTLIL::Cell *driver_lut = it->second;
+			RTLIL::SigBit a_bit = not_cell->getPort("\\A");
+			RTLIL::SigBit y_bit = not_cell->getPort("\\Y");
+			RTLIL::Const driver_mask;
+
+			a_bit.wire = module->wires_.at(remap_name(a_bit.wire->name));
+			y_bit.wire = module->wires_.at(remap_name(y_bit.wire->name));
+
+			auto jt = bit2sinks.find(a_bit);
+			if (jt == bit2sinks.end())
+				goto clone_lut;
+
+			for (auto sink_cell : jt->second)
+				if (sink_cell->type != "$lut")
+					goto clone_lut;
+
+			// Push downstream LUTs past inverter
+			for (auto sink_cell : jt->second) {
+				SigSpec A = sink_cell->getPort("\\A");
+				RTLIL::Const mask = sink_cell->getParam("\\LUT");
+				int index = 0;
+				for (; index < GetSize(A); index++)
+					if (A[index] == a_bit)
+						break;
+				log_assert(index < GetSize(A));
+				int i = 0;
+				while (i < GetSize(mask)) {
+					for (int j = 0; j < (1 << index); j++)
+						std::swap(mask[i+j], mask[i+j+(1 << index)]);
+					i += 1 << (index+1);
+				}
+				A[index] = y_bit;
+				sink_cell->setPort("\\A", A);
+				sink_cell->setParam("\\LUT", mask);
+			}
+
+			// Since we have rewritten all sinks (which we know
+			// to be only LUTs) to be after the inverter, we can
+			// go ahead and clone the LUT with the expectation
+			// that the original driving LUT will become dangling
+			// and get cleaned away
+clone_lut:
+			driver_mask = driver_lut->getParam("\\LUT");
+			for (auto &b : driver_mask.bits) {
+				if (b == RTLIL::State::S0) b = RTLIL::State::S1;
+				else if (b == RTLIL::State::S1) b = RTLIL::State::S0;
+			}
+			auto cell = module->addLut(NEW_ID,
+					driver_lut->getPort("\\A"),
+					y_bit,
+					driver_mask);
+			for (auto &bit : cell->connections_.at("\\A")) {
+				bit.wire = module->wires_.at(remap_name(bit.wire->name));
+				bit2sinks[bit].push_back(cell);
+			}
+		}
+
 		//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);

tests/various/abc9.ys

@@ -19,6 +19,6 @@ hierarchy -top abc9_test028
 proc
 
 abc9 -lut 4
-select -assert-count 1 t:$lut r:LUT=1 r:WIDTH=1 %i %i
+select -assert-count 1 t:$lut r:LUT=2'b01 r:WIDTH=1 %i %i
 select -assert-count 1 t:unknown
 select -assert-none t:$lut t:unknown %% t: %D