diff --git a/Makefile b/Makefile
index bb26eab..5e5c4e6 100644
--- a/Makefile
+++ b/Makefile
@@ -88,7 +88,7 @@
 PLUGIN_LDFLAGS += -undefined dynamic_lookup
 
 # homebrew search paths
-ifneq ($(shell command -v brew),)
+ifneq ($(shell :; command -v brew),)
 BREW_PREFIX := $(shell brew --prefix)/opt
 $(info $$BREW_PREFIX is [${BREW_PREFIX}])
 ifeq ($(ENABLE_PYOSYS),1)
@@ -102,8 +102,8 @@
 export PATH := $(BREW_PREFIX)/bison/bin:$(BREW_PREFIX)/gettext/bin:$(BREW_PREFIX)/flex/bin:$(PATH)
 
 # macports search paths
-else ifneq ($(shell command -v port),)
-PORT_PREFIX := $(patsubst %/bin/port,%,$(shell command -v port))
+else ifneq ($(shell :; command -v port),)
+PORT_PREFIX := $(patsubst %/bin/port,%,$(shell :; command -v port))
 CXXFLAGS += -I$(PORT_PREFIX)/include
 LDFLAGS += -L$(PORT_PREFIX)/lib
 PKG_CONFIG_PATH := $(PORT_PREFIX)/lib/pkgconfig:$(PKG_CONFIG_PATH)
@@ -115,7 +115,7 @@
 LDLIBS += -lrt
 endif
 
-YOSYS_VER := 0.9+36
+YOSYS_VER := 0.9+231
 GIT_REV := $(shell cd $(YOSYS_SRC) && git rev-parse --short HEAD 2> /dev/null || echo UNKNOWN)
 OBJS = kernel/version_$(GIT_REV).o
 
diff --git a/README.md b/README.md
index e0a95a9..af3333e 100644
--- a/README.md
+++ b/README.md
@@ -332,6 +332,10 @@
   that represent module parameters or localparams (when the HDL front-end
   is run in ``-pwires`` mode).
 
+- Wires marked with the ``hierconn`` attribute are connected to wires with the
+  same name (format ``cell_name.identifier``) when they are imported from
+  sub-modules by ``flatten``.
+
 - The ``clkbuf_driver`` attribute can be set on an output port of a blackbox
   module to mark it as a clock buffer output, and thus prevent ``clkbufmap``
   from inserting another clock buffer on a net driven by such output.
@@ -351,19 +355,16 @@
   blackbox or whitebox definition to a corresponding entry in a `abc9`
   box-file.
 
-- The port attribute ``abc_scc_break`` indicates a module input port that will
-  be treated as a primary output during `abc9` techmapping. Doing so eliminates
-  the possibility of a strongly-connected component (i.e. a combinatorial loop)
-  existing. Typically, this is specified for sequential inputs on otherwise
-  combinatorial boxes -- for example, applying ``abc_scc_break`` onto the `D`
-  port of a LUTRAM cell prevents `abc9` from interpreting any `Q` -> `D` paths
-  as a combinatorial loop.
-
 - The port attribute ``abc_carry`` marks the carry-in (if an input port) and
   carry-out (if output port) ports of a box. This information is necessary for
   `abc9` to preserve the integrity of carry-chains. Specifying this attribute
   onto a bus port will affect only its most significant bit.
 
+- The port attribute ``abc_arrival`` specifies an integer (for output ports
+  only) to be used as the arrival time of this sequential port. It can be used,
+  for example, to specify the clk-to-Q delay of a flip-flop for consideration
+  during techmapping.
+
 - In addition to the ``(* ... *)`` attribute syntax, Yosys supports
   the non-standard ``{* ... *}`` attribute syntax to set default attributes
   for everything that comes after the ``{* ... *}`` statement. (Reset
diff --git a/backends/aiger/xaiger.cc b/backends/aiger/xaiger.cc
index e1b8423..fa6ba0a 100644
--- a/backends/aiger/xaiger.cc
+++ b/backends/aiger/xaiger.cc
@@ -83,6 +83,7 @@
 	dict<SigBit, pair<SigBit, SigBit>> and_map;
 	vector<std::tuple<SigBit,RTLIL::Cell*,RTLIL::IdString,int>> ci_bits;
 	vector<std::tuple<SigBit,RTLIL::Cell*,RTLIL::IdString,int,int>> co_bits;
+	dict<SigBit, float> arrival_times;
 
 	vector<pair<int, int>> aig_gates;
 	vector<int> aig_outputs;
@@ -247,14 +248,15 @@
 				if (!holes_mode) {
 					toposort.node(cell->name);
 					for (const auto &conn : cell->connections()) {
-						if (cell->input(conn.first)) {
+						auto port_wire = inst_module->wire(conn.first);
+						if (port_wire->port_input) {
 							// Ignore inout for the sake of topographical ordering
-							if (cell->output(conn.first)) continue;
+							if (port_wire->port_output) continue;
 							for (auto bit : sigmap(conn.second))
 								bit_users[bit].insert(cell->name);
 						}
 
-						if (cell->output(conn.first))
+						if (port_wire->port_output)
 							for (auto bit : sigmap(conn.second))
 								bit_drivers[bit].insert(cell->name);
 					}
@@ -271,7 +273,7 @@
 						log_error("Connection '%s' on cell '%s' (type '%s') not recognised!\n", log_id(c.first), log_id(cell), log_id(cell->type));
 
 					if (is_input) {
-						for (auto b : c.second.bits()) {
+						for (auto b : c.second) {
 							Wire *w = b.wire;
 							if (!w) continue;
 							if (!w->port_output || !cell_known) {
@@ -287,7 +289,17 @@
 						}
 					}
 					if (is_output) {
-						for (auto b : c.second.bits()) {
+						int arrival = 0;
+						if (port_wire) {
+							auto it = port_wire->attributes.find("\\abc_arrival");
+							if (it != port_wire->attributes.end()) {
+								if (it->second.flags != 0)
+									log_error("Attribute 'abc_arrival' on port '%s' of module '%s' is not an integer.\n", log_id(port_wire), log_id(cell->type));
+								arrival = it->second.as_int();
+							}
+						}
+
+						for (auto b : c.second) {
 							Wire *w = b.wire;
 							if (!w) continue;
 							input_bits.insert(b);
@@ -295,6 +307,9 @@
 							if (O != b)
 								alias_map[O] = b;
 							undriven_bits.erase(O);
+
+							if (arrival)
+								arrival_times[b] = arrival;
 						}
 					}
 				}
@@ -489,16 +504,16 @@
 			aig_outputs.push_back(bit2aig(bit));
 		}
 
+		if (output_bits.empty()) {
+			output_bits.insert(State::S0);
+			omode = true;
+		}
+
 		for (auto bit : output_bits) {
 			ordered_outputs[bit] = aig_o++;
 			aig_outputs.push_back(bit2aig(bit));
 		}
 
-		if (output_bits.empty()) {
-			aig_o++;
-			aig_outputs.push_back(0);
-			omode = true;
-		}
 	}
 
 	void write_aiger(std::ostream &f, bool ascii_mode)
@@ -560,26 +575,38 @@
 
 		f << "c";
 
+		log_assert(!output_bits.empty());
+		auto write_buffer = [](std::stringstream &buffer, int i32) {
+			int32_t i32_be = to_big_endian(i32);
+			buffer.write(reinterpret_cast<const char*>(&i32_be), sizeof(i32_be));
+		};
+		std::stringstream h_buffer;
+		auto write_h_buffer = std::bind(write_buffer, std::ref(h_buffer), std::placeholders::_1);
+		write_h_buffer(1);
+		log_debug("ciNum = %d\n", GetSize(input_bits) + GetSize(ci_bits));
+		write_h_buffer(input_bits.size() + ci_bits.size());
+		log_debug("coNum = %d\n", GetSize(output_bits) + GetSize(co_bits));
+		write_h_buffer(output_bits.size() + GetSize(co_bits));
+		log_debug("piNum = %d\n", GetSize(input_bits));
+		write_h_buffer(input_bits.size());
+		log_debug("poNum = %d\n", GetSize(output_bits));
+		write_h_buffer(output_bits.size());
+		log_debug("boxNum = %d\n", GetSize(box_list));
+		write_h_buffer(box_list.size());
+
+		auto write_buffer_float = [](std::stringstream &buffer, float f32) {
+			buffer.write(reinterpret_cast<const char*>(&f32), sizeof(f32));
+		};
+		std::stringstream i_buffer;
+		auto write_i_buffer = std::bind(write_buffer_float, std::ref(i_buffer), std::placeholders::_1);
+		for (auto bit : input_bits)
+			write_i_buffer(arrival_times.at(bit, 0));
+		//std::stringstream o_buffer;
+		//auto write_o_buffer = std::bind(write_buffer_float, std::ref(o_buffer), std::placeholders::_1);
+		//for (auto bit : output_bits)
+		//	write_o_buffer(0);
+
 		if (!box_list.empty()) {
-			auto write_buffer = [](std::stringstream &buffer, int i32) {
-				int32_t i32_be = to_big_endian(i32);
-				buffer.write(reinterpret_cast<const char*>(&i32_be), sizeof(i32_be));
-			};
-
-			std::stringstream h_buffer;
-			auto write_h_buffer = std::bind(write_buffer, std::ref(h_buffer), std::placeholders::_1);
-			write_h_buffer(1);
-			log_debug("ciNum = %d\n", GetSize(input_bits) + GetSize(ci_bits));
-			write_h_buffer(input_bits.size() + ci_bits.size());
-			log_debug("coNum = %d\n", GetSize(output_bits) + GetSize(co_bits));
-			write_h_buffer(output_bits.size() + co_bits.size());
-			log_debug("piNum = %d\n", GetSize(input_bits));
-			write_h_buffer(input_bits.size());
-			log_debug("poNum = %d\n", GetSize(output_bits));
-			write_h_buffer(output_bits.size());
-			log_debug("boxNum = %d\n", GetSize(box_list));
-			write_h_buffer(box_list.size());
-
 			RTLIL::Module *holes_module = module->design->addModule("$__holes__");
 			log_assert(holes_module);
 
@@ -643,19 +670,12 @@
 				write_h_buffer(box_count++);
 			}
 
-			f << "h";
-			std::string buffer_str = h_buffer.str();
-			int32_t buffer_size_be = to_big_endian(buffer_str.size());
-			f.write(reinterpret_cast<const char*>(&buffer_size_be), sizeof(buffer_size_be));
-			f.write(buffer_str.data(), buffer_str.size());
-
 			std::stringstream r_buffer;
 			auto write_r_buffer = std::bind(write_buffer, std::ref(r_buffer), std::placeholders::_1);
 			write_r_buffer(0);
-
 			f << "r";
-			buffer_str = r_buffer.str();
-			buffer_size_be = to_big_endian(buffer_str.size());
+			std::string buffer_str = r_buffer.str();
+			int32_t buffer_size_be = to_big_endian(buffer_str.size());
 			f.write(reinterpret_cast<const char*>(&buffer_size_be), sizeof(buffer_size_be));
 			f.write(buffer_str.data(), buffer_str.size());
 
@@ -709,6 +729,23 @@
 			}
 		}
 
+		f << "h";
+		std::string buffer_str = h_buffer.str();
+		int32_t buffer_size_be = to_big_endian(buffer_str.size());
+		f.write(reinterpret_cast<const char*>(&buffer_size_be), sizeof(buffer_size_be));
+		f.write(buffer_str.data(), buffer_str.size());
+
+		f << "i";
+		buffer_str = i_buffer.str();
+		buffer_size_be = to_big_endian(buffer_str.size());
+		f.write(reinterpret_cast<const char*>(&buffer_size_be), sizeof(buffer_size_be));
+		f.write(buffer_str.data(), buffer_str.size());
+		//f << "o";
+		//buffer_str = o_buffer.str();
+		//buffer_size_be = to_big_endian(buffer_str.size());
+		//f.write(reinterpret_cast<const char*>(&buffer_size_be), sizeof(buffer_size_be));
+		//f.write(buffer_str.data(), buffer_str.size());
+
 		f << stringf("Generated by %s\n", yosys_version_str);
 	}
 
@@ -760,11 +797,11 @@
 			f << stringf("box %d %d %s\n", box_count++, 0, log_id(cell->name));
 
 		output_lines.sort();
+		if (omode)
+			output_lines[State::S0] = "output 0 0 $__dummy__\n";
 		for (auto &it : output_lines)
 			f << it.second;
 		log_assert(output_lines.size() == output_bits.size());
-		if (omode && output_bits.empty())
-			f << "output " << output_lines.size() << " 0 $__dummy__\n";
 
 		wire_lines.sort();
 		for (auto &it : wire_lines)
diff --git a/frontends/aiger/aigerparse.cc b/frontends/aiger/aigerparse.cc
index 2e1fb8f..a8d5abc 100644
--- a/frontends/aiger/aigerparse.cc
+++ b/frontends/aiger/aigerparse.cc
@@ -430,6 +430,7 @@
 			else if (c == 'r') {
 				uint32_t dataSize YS_ATTRIBUTE(unused) = parse_xaiger_literal(f);
 				flopNum = parse_xaiger_literal(f);
+				log_debug("flopNum: %u\n", flopNum);
 				log_assert(dataSize == (flopNum+1) * sizeof(uint32_t));
 				f.ignore(flopNum * sizeof(uint32_t));
 			}
@@ -496,8 +497,7 @@
 
 	// Parse latches
 	RTLIL::Wire *clk_wire = nullptr;
-	if (L > 0) {
-		log_assert(clk_name != "");
+	if (L > 0 && !clk_name.empty()) {
 		clk_wire = module->wire(clk_name);
 		log_assert(!clk_wire);
 		log_debug2("Creating %s\n", clk_name.c_str());
@@ -513,7 +513,10 @@
 		RTLIL::Wire *q_wire = createWireIfNotExists(module, l1);
 		RTLIL::Wire *d_wire = createWireIfNotExists(module, l2);
 
-		module->addDffGate(NEW_ID, clk_wire, d_wire, q_wire);
+		if (clk_wire)
+			module->addDffGate(NEW_ID, clk_wire, d_wire, q_wire);
+		else
+			module->addFfGate(NEW_ID, d_wire, q_wire);
 
 		// Reset logic is optional in AIGER 1.9
 		if (f.peek() == ' ') {
@@ -621,8 +624,7 @@
 
 	// Parse latches
 	RTLIL::Wire *clk_wire = nullptr;
-	if (L > 0) {
-		log_assert(clk_name != "");
+	if (L > 0 && !clk_name.empty()) {
 		clk_wire = module->wire(clk_name);
 		log_assert(!clk_wire);
 		log_debug2("Creating %s\n", clk_name.c_str());
@@ -638,7 +640,10 @@
 		RTLIL::Wire *q_wire = createWireIfNotExists(module, l1);
 		RTLIL::Wire *d_wire = createWireIfNotExists(module, l2);
 
-		module->addDff(NEW_ID, clk_wire, d_wire, q_wire);
+		if (clk_wire)
+			module->addDff(NEW_ID, clk_wire, d_wire, q_wire);
+		else
+			module->addFf(NEW_ID, d_wire, q_wire);
 
 		// Reset logic is optional in AIGER 1.9
 		if (f.peek() == ' ') {
@@ -776,19 +781,19 @@
 		// NB: Assume box_module->ports are sorted alphabetically
 		//     (as RTLIL::Module::fixup_ports() would do)
 		for (auto port_name : box_module->ports) {
-			RTLIL::Wire* w = box_module->wire(port_name);
-			log_assert(w);
+			RTLIL::Wire* port = box_module->wire(port_name);
+			log_assert(port);
 			RTLIL::SigSpec rhs;
-			RTLIL::Wire* wire = nullptr;
-			for (int i = 0; i < GetSize(w); i++) {
-				if (w->port_input) {
+			for (int i = 0; i < GetSize(port); i++) {
+				RTLIL::Wire* wire = nullptr;
+				if (port->port_input) {
 					log_assert(co_count < outputs.size());
 					wire = outputs[co_count++];
 					log_assert(wire);
 					log_assert(wire->port_output);
 					wire->port_output = false;
 				}
-				if (w->port_output) {
+				if (port->port_output) {
 					log_assert((piNum + ci_count) < inputs.size());
 					wire = inputs[piNum + ci_count++];
 					log_assert(wire);
@@ -797,6 +802,7 @@
 				}
 				rhs.append(wire);
 			}
+
 			cell->setPort(port_name, rhs);
 		}
 	}
@@ -814,6 +820,7 @@
 				RTLIL::Wire* wire = inputs[variable];
 				log_assert(wire);
 				log_assert(wire->port_input);
+				log_debug("Renaming input %s", log_id(wire));
 
 				if (index == 0) {
 					// Cope with the fact that a CI might be identical
@@ -840,6 +847,7 @@
 						wire->port_input = false;
 					}
 				}
+				log_debug(" -> %s\n", log_id(wire));
 			}
 			else if (type == "output") {
 				log_assert(static_cast<unsigned>(variable + co_count) < outputs.size());
@@ -850,6 +858,7 @@
 					wire->port_output = false;
 					continue;
 				}
+				log_debug("Renaming output %s", log_id(wire));
 
 				if (index == 0) {
 					// Cope with the fact that a CO might be identical
@@ -871,6 +880,7 @@
 					else {
 						wire->port_output = false;
 						module->connect(wire, existing);
+						wire = existing;
 					}
 				}
 				else if (index > 0) {
@@ -896,6 +906,7 @@
 						wire->port_output = false;
 					}
 				}
+				log_debug(" -> %s\n", log_id(wire));
 			}
 			else if (type == "box") {
 				RTLIL::Cell* cell = module->cell(stringf("$__box%d__", variable));
@@ -1004,8 +1015,8 @@
 		log("        Name of module to be created (default: <filename>)\n");
 		log("\n");
 		log("    -clk_name <wire_name>\n");
-		log("        AIGER latches to be transformed into posedge DFFs clocked by wire of");
-		log("        this name (default: clk)\n");
+		log("        If specified, AIGER latches to be transformed into $_DFF_P_ cells\n");
+		log("        clocked by wire of this name. Otherwise, $_FF_ cells will be used.\n");
 		log("\n");
 		log("    -map <filename>\n");
 		log("        read file with port and latch symbols\n");
diff --git a/frontends/ast/simplify.cc b/frontends/ast/simplify.cc
index 86dd80c..52fcf3e 100644
--- a/frontends/ast/simplify.cc
+++ b/frontends/ast/simplify.cc
@@ -1530,10 +1530,16 @@
 		current_scope[wire_en->str] = wire_en;
 		while (wire_en->simplify(true, false, false, 1, -1, false, false)) { }
 
-		std::vector<RTLIL::State> x_bit;
-		x_bit.push_back(RTLIL::State::Sx);
+		AstNode *check_defval;
+		if (type == AST_LIVE || type == AST_FAIR) {
+			check_defval = new AstNode(AST_REDUCE_BOOL, children[0]->clone());
+		} else {
+			std::vector<RTLIL::State> x_bit;
+			x_bit.push_back(RTLIL::State::Sx);
+			check_defval = mkconst_bits(x_bit, false);
+		}
 
-		AstNode *assign_check = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_bits(x_bit, false));
+		AstNode *assign_check = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), check_defval);
 		assign_check->children[0]->str = id_check;
 		assign_check->children[0]->was_checked = true;
 
@@ -1546,9 +1552,13 @@
 		default_signals->children.push_back(assign_en);
 		current_top_block->children.insert(current_top_block->children.begin(), default_signals);
 
-		assign_check = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), new AstNode(AST_REDUCE_BOOL, children[0]->clone()));
-		assign_check->children[0]->str = id_check;
-		assign_check->children[0]->was_checked = true;
+		if (type == AST_LIVE || type == AST_FAIR) {
+			assign_check = nullptr;
+		} else {
+			assign_check = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), new AstNode(AST_REDUCE_BOOL, children[0]->clone()));
+			assign_check->children[0]->str = id_check;
+			assign_check->children[0]->was_checked = true;
+		}
 
 		if (current_always == nullptr || current_always->type != AST_INITIAL) {
 			assign_en = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_int(1, false, 1));
@@ -1560,7 +1570,8 @@
 		assign_en->children[0]->was_checked = true;
 
 		newNode = new AstNode(AST_BLOCK);
-		newNode->children.push_back(assign_check);
+		if (assign_check != nullptr)
+			newNode->children.push_back(assign_check);
 		newNode->children.push_back(assign_en);
 
 		AstNode *assertnode = new AstNode(type);
diff --git a/passes/techmap/abc9.cc b/passes/techmap/abc9.cc
index 6fdf987..7eac08d 100644
--- a/passes/techmap/abc9.cc
+++ b/passes/techmap/abc9.cc
@@ -76,8 +76,7 @@
 	return stringf("$abc$%d$%s", map_autoidx, abc_name.c_str()+1);
 }
 
-void handle_loops(RTLIL::Design *design,
-		const dict<IdString,pool<IdString>> &scc_break_inputs)
+void handle_loops(RTLIL::Design *design)
 {
 	Pass::call(design, "scc -set_attr abc_scc_id {}");
 
@@ -114,30 +113,6 @@
 			}
 			cell->attributes.erase(it);
 		}
-
-		auto jt = scc_break_inputs.find(cell->type);
-		if (jt != scc_break_inputs.end())
-			for (auto port_name : jt->second) {
-				RTLIL::SigSpec sig;
-				auto &rhs = cell->connections_.at(port_name);
-				for (auto b : rhs) {
-					Wire *w = b.wire;
-					if (!w) continue;
-					w->port_output = true;
-					w->set_bool_attribute(ID(abc_scc_break));
-					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_input = true;
-					}
-					else {
-						log_assert(b.offset < GetSize(w));
-						log_assert(w->port_input);
-					}
-					sig.append(RTLIL::SigBit(w, b.offset));
-				}
-				rhs = sig;
-			}
 	}
 
 	module->fixup_ports();
@@ -272,8 +247,7 @@
 		bool cleanup, vector<int> lut_costs, bool dff_mode, std::string clk_str,
 		bool /*keepff*/, std::string delay_target, std::string /*lutin_shared*/, bool fast_mode,
 		bool show_tempdir, std::string box_file, std::string lut_file,
-		std::string wire_delay, const dict<int,IdString> &box_lookup,
-		const dict<IdString,pool<IdString>> &scc_break_inputs
+		std::string wire_delay, const dict<int,IdString> &box_lookup
 )
 {
 	module = current_module;
@@ -413,7 +387,7 @@
 		RTLIL::Selection& sel = design->selection_stack.back();
 		sel.select(module);
 
-		handle_loops(design, scc_break_inputs);
+		handle_loops(design);
 
 		Pass::call(design, "aigmap");
 
@@ -1050,9 +1024,6 @@
 			}
 			if (arg == "-box" && argidx+1 < args.size()) {
 				box_file = args[++argidx];
-				rewrite_filename(box_file);
-				if (!box_file.empty() && !is_absolute_path(box_file))
-					box_file = std::string(pwd) + "/" + box_file;
 				continue;
 			}
 			if (arg == "-W" && argidx+1 < args.size()) {
@@ -1063,8 +1034,15 @@
 		}
 		extra_args(args, argidx, design);
 
+		// ABC expects a box file for XAIG
+		if (box_file.empty())
+		    box_file = "+/dummy.box";
+
+		rewrite_filename(box_file);
+		if (!box_file.empty() && !is_absolute_path(box_file))
+		    box_file = std::string(pwd) + "/" + box_file;
+
 		dict<int,IdString> box_lookup;
-		dict<IdString,pool<IdString>> scc_break_inputs;
 		for (auto m : design->modules()) {
 			auto it = m->attributes.find(ID(abc_box_id));
 			if (it == m->attributes.end())
@@ -1082,17 +1060,13 @@
 			for (auto p : m->ports) {
 				auto w = m->wire(p);
 				log_assert(w);
-				if (w->port_input) {
-					if (w->attributes.count(ID(abc_scc_break)))
-						scc_break_inputs[m->name].insert(p);
-					if (w->attributes.count(ID(abc_carry))) {
+				if (w->attributes.count(ID(abc_carry))) {
+					if (w->port_input) {
 						if (carry_in)
 							log_error("Module '%s' contains more than one 'abc_carry' input port.\n", log_id(m));
 						carry_in = w;
 					}
-				}
-				if (w->port_output) {
-					if (w->attributes.count(ID(abc_carry))) {
+					else if (w->port_output) {
 						if (carry_out)
 							log_error("Module '%s' contains more than one 'abc_carry' input port.\n", log_id(m));
 						carry_out = w;
@@ -1144,7 +1118,7 @@
 			if (!dff_mode || !clk_str.empty()) {
 				abc9_module(design, mod, script_file, exe_file, cleanup, lut_costs, dff_mode, clk_str, keepff,
 						delay_target, lutin_shared, fast_mode, show_tempdir,
-						box_file, lut_file, wire_delay, box_lookup, scc_break_inputs);
+						box_file, lut_file, wire_delay, box_lookup);
 				continue;
 			}
 
@@ -1290,7 +1264,7 @@
 				en_sig = assign_map(std::get<3>(it.first));
 				abc9_module(design, mod, script_file, exe_file, cleanup, lut_costs, !clk_sig.empty(), "$",
 						keepff, delay_target, lutin_shared, fast_mode, show_tempdir,
-						box_file, lut_file, wire_delay, box_lookup, scc_break_inputs);
+						box_file, lut_file, wire_delay, box_lookup);
 				assign_map.set(mod);
 			}
 		}
diff --git a/passes/techmap/techmap.cc b/passes/techmap/techmap.cc
index c4496f7..5ce1bf7 100644
--- a/passes/techmap/techmap.cc
+++ b/passes/techmap/techmap.cc
@@ -205,20 +205,38 @@
 		}
 
 		std::map<RTLIL::IdString, RTLIL::IdString> positional_ports;
+		dict<Wire*, IdString> temp_renamed_wires;
 
 		for (auto &it : tpl->wires_) {
 			if (it.second->port_id > 0)
 				positional_ports[stringf("$%d", it.second->port_id)] = it.first;
 			IdString w_name = it.second->name;
 			apply_prefix(cell->name, w_name);
-			RTLIL::Wire *w = module->addWire(w_name, it.second);
-			w->port_input = false;
-			w->port_output = false;
-			w->port_id = 0;
-			if (it.second->get_bool_attribute(ID(_techmap_special_)))
-				w->attributes.clear();
-			if (w->attributes.count(ID(src)))
-				w->add_strpool_attribute(ID(src), extra_src_attrs);
+			RTLIL::Wire *w = module->wire(w_name);
+			if (w != nullptr) {
+				if (!flatten_mode || !w->get_bool_attribute(ID(hierconn))) {
+					temp_renamed_wires[w] = w->name;
+					module->rename(w, NEW_ID);
+					w = nullptr;
+				} else {
+					w->attributes.erase(ID(hierconn));
+					if (GetSize(w) < GetSize(it.second)) {
+						log_warning("Widening signal %s.%s to match size of %s.%s (via %s.%s).\n", log_id(module), log_id(w),
+								log_id(tpl), log_id(it.second), log_id(module), log_id(cell));
+						w->width = GetSize(it.second);
+					}
+				}
+			}
+			if (w == nullptr) {
+				w = module->addWire(w_name, it.second);
+				w->port_input = false;
+				w->port_output = false;
+				w->port_id = 0;
+				if (it.second->get_bool_attribute(ID(_techmap_special_)))
+					w->attributes.clear();
+				if (w->attributes.count(ID(src)))
+					w->add_strpool_attribute(ID(src), extra_src_attrs);
+			}
 			design->select(module, w);
 		}
 
@@ -380,6 +398,16 @@
 		}
 
 		module->remove(cell);
+
+		for (auto &it : temp_renamed_wires)
+		{
+			Wire *w = it.first;
+			IdString name = it.second;
+			IdString altname = module->uniquify(name);
+			Wire *other_w = module->wire(name);
+			module->rename(other_w, altname);
+			module->rename(w, name);
+		}
 	}
 
 	bool techmap_module(RTLIL::Design *design, RTLIL::Module *module, RTLIL::Design *map, std::set<RTLIL::Cell*> &handled_cells,
diff --git a/techlibs/common/Makefile.inc b/techlibs/common/Makefile.inc
index 0e05620..de94798 100644
--- a/techlibs/common/Makefile.inc
+++ b/techlibs/common/Makefile.inc
@@ -28,3 +28,4 @@
 $(eval $(call add_share_file,share,techlibs/common/gate2lut.v))
 $(eval $(call add_share_file,share,techlibs/common/cmp2lut.v))
 $(eval $(call add_share_file,share,techlibs/common/cells.lib))
+$(eval $(call add_share_file,share,techlibs/common/dummy.box))
diff --git a/techlibs/common/dummy.box b/techlibs/common/dummy.box
new file mode 100644
index 0000000..0c18070
--- /dev/null
+++ b/techlibs/common/dummy.box
@@ -0,0 +1 @@
+(dummy) 1 0 0 0
diff --git a/techlibs/ecp5/Makefile.inc b/techlibs/ecp5/Makefile.inc
index 2143aca..9efb634 100644
--- a/techlibs/ecp5/Makefile.inc
+++ b/techlibs/ecp5/Makefile.inc
@@ -14,6 +14,9 @@
 $(eval $(call add_share_file,share/ecp5,techlibs/ecp5/arith_map.v))
 $(eval $(call add_share_file,share/ecp5,techlibs/ecp5/latches_map.v))
 
+$(eval $(call add_share_file,share/ecp5,techlibs/ecp5/abc_map.v))
+$(eval $(call add_share_file,share/ecp5,techlibs/ecp5/abc_unmap.v))
+$(eval $(call add_share_file,share/ecp5,techlibs/ecp5/abc_model.v))
 $(eval $(call add_share_file,share/ecp5,techlibs/ecp5/abc_5g.box))
 $(eval $(call add_share_file,share/ecp5,techlibs/ecp5/abc_5g.lut))
 $(eval $(call add_share_file,share/ecp5,techlibs/ecp5/abc_5g_nowide.lut))
diff --git a/techlibs/ecp5/abc_5g.box b/techlibs/ecp5/abc_5g.box
index c757d13..a336b4a 100644
--- a/techlibs/ecp5/abc_5g.box
+++ b/techlibs/ecp5/abc_5g.box
@@ -15,16 +15,16 @@
 630  379  630  379  526   275  392  141  273
 516  516  516  516  412   412  278  278  43
 
-# Box 2 : TRELLIS_DPR16X4 (16x4 dist ram)
+# Box 2 : TRELLIS_DPR16X4_COMB (16x4 dist ram)
 # Outputs: DO0, DO1, DO2, DO3
-# name            ID  w/b   ins   outs
-TRELLIS_DPR16X4   2     0   14    4
+# name               ID  w/b   ins   outs
+$__ABC_DPR16X4_COMB  2     0   8    4
 
-#DI0   DI1   DI2   DI3   RAD0   RAD1   RAD2   RAD3   WAD0    WAD1   WAD2   WAD3  WCK   WRE
--      -     -     -     141    379    275    379    -       -      -      -     -     -
--      -     -     -     141    379    275    379    -       -      -      -     -     -
--      -     -     -     141    379    275    379    -       -      -      -     -     -
--      -     -     -     141    379    275    379    -       -      -      -     -     -
+#A0   A1   A2   A3   RAD0   RAD1   RAD2   RAD3
+0     0    0    0    141    379    275    379
+0     0    0    0    141    379    275    379
+0     0    0    0    141    379    275    379
+0     0    0    0    141    379    275    379
 
 # Box 3 : PFUMX (MUX2)
 # Outputs: Z
diff --git a/techlibs/ecp5/abc_map.v b/techlibs/ecp5/abc_map.v
new file mode 100644
index 0000000..ffd25f0
--- /dev/null
+++ b/techlibs/ecp5/abc_map.v
@@ -0,0 +1,24 @@
+// ---------------------------------------
+
+module TRELLIS_DPR16X4 (
+	input  [3:0] DI,
+	input  [3:0] WAD,
+	input        WRE,
+	input        WCK,
+	input  [3:0] RAD,
+	output [3:0] DO
+);
+	parameter WCKMUX = "WCK";
+	parameter WREMUX = "WRE";
+	parameter [63:0] INITVAL = 64'h0000000000000000;
+    wire [3:0] \$DO ;
+
+    TRELLIS_DPR16X4 #(
+      .WCKMUX(WCKMUX), .WREMUX(WREMUX), .INITVAL(INITVAL)
+    ) _TECHMAP_REPLACE_ (
+      .DI(DI), .WAD(WAD), .WRE(WRE), .WCK(WCK),
+      .RAD(RAD), .DO(\$DO )
+    );
+
+    \$__ABC_DPR16X4_COMB do (.A(\$DO ), .S(RAD), .Y(DO));
+endmodule
diff --git a/techlibs/ecp5/abc_model.v b/techlibs/ecp5/abc_model.v
new file mode 100644
index 0000000..56a733b
--- /dev/null
+++ b/techlibs/ecp5/abc_model.v
@@ -0,0 +1,5 @@
+// ---------------------------------------
+
+(* abc_box_id=2 *)
+module \$__ABC_DPR16X4_COMB (input [3:0] A, S, output [3:0] Y);
+endmodule
diff --git a/techlibs/ecp5/abc_unmap.v b/techlibs/ecp5/abc_unmap.v
new file mode 100644
index 0000000..d43cdd9
--- /dev/null
+++ b/techlibs/ecp5/abc_unmap.v
@@ -0,0 +1,5 @@
+// ---------------------------------------
+
+module \$__ABC_DPR16X4_COMB (input [3:0] A, S, output [3:0] Y);
+    assign Y = A;
+endmodule
diff --git a/techlibs/ecp5/cells_sim.v b/techlibs/ecp5/cells_sim.v
index 5bdb839..db77dc1 100644
--- a/techlibs/ecp5/cells_sim.v
+++ b/techlibs/ecp5/cells_sim.v
@@ -109,16 +109,13 @@
 endmodule
 
 // ---------------------------------------
-//(* abc_box_id=2 *)
 module TRELLIS_DPR16X4 (
-	(* abc_scc_break *)
 	input  [3:0] DI,
-	(* abc_scc_break *)
 	input  [3:0] WAD,
-	(* abc_scc_break *)
 	input        WRE,
 	input        WCK,
 	input  [3:0] RAD,
+	/* (* abc_arrival=<TODO> *) */
 	output [3:0] DO
 );
 	parameter WCKMUX = "WCK";
diff --git a/techlibs/ecp5/synth_ecp5.cc b/techlibs/ecp5/synth_ecp5.cc
index a8075e8..2593546 100644
--- a/techlibs/ecp5/synth_ecp5.cc
+++ b/techlibs/ecp5/synth_ecp5.cc
@@ -280,12 +280,17 @@
 			if (abc2 || help_mode) {
 				run("abc", "      (only if -abc2)");
 			}
-			run("techmap -map +/ecp5/latches_map.v");
+			std::string techmap_args = "-map +/ecp5/latches_map.v";
+			if (abc9)
+				techmap_args += " -map +/ecp5/abc_map.v -max_iter 1";
+			run("techmap " + techmap_args);
+
 			if (abc9) {
 				if (nowidelut)
 					run("abc9 -lut +/ecp5/abc_5g_nowide.lut -box +/ecp5/abc_5g.box -W 200");
 				else
 					run("abc9 -lut +/ecp5/abc_5g.lut -box +/ecp5/abc_5g.box -W 200");
+				run("techmap -map +/ecp5/abc_unmap.v");
 			} else {
 				if (nowidelut)
 					run("abc -lut 4 -dress");
diff --git a/techlibs/ice40/cells_sim.v b/techlibs/ice40/cells_sim.v
index 2a7487f..8e5e035 100644
--- a/techlibs/ice40/cells_sim.v
+++ b/techlibs/ice40/cells_sim.v
@@ -2,6 +2,10 @@
 `define SB_DFF_REG reg Q = 0
 // `define SB_DFF_REG reg Q
 
+`define ABC_ARRIVAL_HX(TIME) `ifdef ICE40_HX (* abc_arrival=TIME *) `endif
+`define ABC_ARRIVAL_LP(TIME) `ifdef ICE40_LP (* abc_arrival=TIME *) `endif
+`define ABC_ARRIVAL_U(TIME)  `ifdef ICE40_U (* abc_arrival=TIME *) `endif
+
 // SiliconBlue IO Cells
 
 module SB_IO (
@@ -169,20 +173,42 @@
 	);
 endmodule
 
+// Max delay from: https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_hx1k.txt#L90
+//                 https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_lp1k.txt#L90
+//                 https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_up5k.txt#L102
+
 // Positive Edge SiliconBlue FF Cells
 
-module SB_DFF (output `SB_DFF_REG, input C, D);
+module SB_DFF (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, D
+);
 	always @(posedge C)
 		Q <= D;
 endmodule
 
-module SB_DFFE (output `SB_DFF_REG, input C, E, D);
+module SB_DFFE (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, E, D
+);
 	always @(posedge C)
 		if (E)
 			Q <= D;
 endmodule
 
-module SB_DFFSR (output `SB_DFF_REG, input C, R, D);
+module SB_DFFSR (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, R, D
+);
 	always @(posedge C)
 		if (R)
 			Q <= 0;
@@ -190,7 +216,13 @@
 			Q <= D;
 endmodule
 
-module SB_DFFR (output `SB_DFF_REG, input C, R, D);
+module SB_DFFR (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, R, D
+);
 	always @(posedge C, posedge R)
 		if (R)
 			Q <= 0;
@@ -198,7 +230,13 @@
 			Q <= D;
 endmodule
 
-module SB_DFFSS (output `SB_DFF_REG, input C, S, D);
+module SB_DFFSS (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, S, D
+);
 	always @(posedge C)
 		if (S)
 			Q <= 1;
@@ -206,7 +244,13 @@
 			Q <= D;
 endmodule
 
-module SB_DFFS (output `SB_DFF_REG, input C, S, D);
+module SB_DFFS (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, S, D
+);
 	always @(posedge C, posedge S)
 		if (S)
 			Q <= 1;
@@ -214,7 +258,13 @@
 			Q <= D;
 endmodule
 
-module SB_DFFESR (output `SB_DFF_REG, input C, E, R, D);
+module SB_DFFESR (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, E, R, D
+);
 	always @(posedge C)
 		if (E) begin
 			if (R)
@@ -224,7 +274,13 @@
 		end
 endmodule
 
-module SB_DFFER (output `SB_DFF_REG, input C, E, R, D);
+module SB_DFFER (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, E, R, D
+);
 	always @(posedge C, posedge R)
 		if (R)
 			Q <= 0;
@@ -232,7 +288,13 @@
 			Q <= D;
 endmodule
 
-module SB_DFFESS (output `SB_DFF_REG, input C, E, S, D);
+module SB_DFFESS (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, E, S, D
+);
 	always @(posedge C)
 		if (E) begin
 			if (S)
@@ -242,7 +304,13 @@
 		end
 endmodule
 
-module SB_DFFES (output `SB_DFF_REG, input C, E, S, D);
+module SB_DFFES (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, E, S, D
+);
 	always @(posedge C, posedge S)
 		if (S)
 			Q <= 1;
@@ -252,18 +320,36 @@
 
 // Negative Edge SiliconBlue FF Cells
 
-module SB_DFFN (output `SB_DFF_REG, input C, D);
+module SB_DFFN (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, D
+);
 	always @(negedge C)
 		Q <= D;
 endmodule
 
-module SB_DFFNE (output `SB_DFF_REG, input C, E, D);
+module SB_DFFNE (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, E, D
+);
 	always @(negedge C)
 		if (E)
 			Q <= D;
 endmodule
 
-module SB_DFFNSR (output `SB_DFF_REG, input C, R, D);
+module SB_DFFNSR (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, R, D
+);
 	always @(negedge C)
 		if (R)
 			Q <= 0;
@@ -271,7 +357,13 @@
 			Q <= D;
 endmodule
 
-module SB_DFFNR (output `SB_DFF_REG, input C, R, D);
+module SB_DFFNR (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, R, D
+);
 	always @(negedge C, posedge R)
 		if (R)
 			Q <= 0;
@@ -279,7 +371,13 @@
 			Q <= D;
 endmodule
 
-module SB_DFFNSS (output `SB_DFF_REG, input C, S, D);
+module SB_DFFNSS (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, S, D
+);
 	always @(negedge C)
 		if (S)
 			Q <= 1;
@@ -287,7 +385,13 @@
 			Q <= D;
 endmodule
 
-module SB_DFFNS (output `SB_DFF_REG, input C, S, D);
+module SB_DFFNS (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, S, D
+);
 	always @(negedge C, posedge S)
 		if (S)
 			Q <= 1;
@@ -295,7 +399,13 @@
 			Q <= D;
 endmodule
 
-module SB_DFFNESR (output `SB_DFF_REG, input C, E, R, D);
+module SB_DFFNESR (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, E, R, D
+);
 	always @(negedge C)
 		if (E) begin
 			if (R)
@@ -305,7 +415,13 @@
 		end
 endmodule
 
-module SB_DFFNER (output `SB_DFF_REG, input C, E, R, D);
+module SB_DFFNER (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, E, R, D
+);
 	always @(negedge C, posedge R)
 		if (R)
 			Q <= 0;
@@ -313,7 +429,13 @@
 			Q <= D;
 endmodule
 
-module SB_DFFNESS (output `SB_DFF_REG, input C, E, S, D);
+module SB_DFFNESS (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, E, S, D
+);
 	always @(negedge C)
 		if (E) begin
 			if (S)
@@ -323,7 +445,13 @@
 		end
 endmodule
 
-module SB_DFFNES (output `SB_DFF_REG, input C, E, S, D);
+module SB_DFFNES (
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output `SB_DFF_REG,
+	input C, E, S, D
+);
 	always @(negedge C, posedge S)
 		if (S)
 			Q <= 1;
@@ -334,6 +462,9 @@
 // SiliconBlue RAM Cells
 
 module SB_RAM40_4K (
+	`ABC_ARRIVAL_HX(2146) // https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_hx1k.txt#L401
+	`ABC_ARRIVAL_LP(3163) // https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_lp1k.txt#L401
+	`ABC_ARRIVAL_U(1179)  // https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_up5k.txt#L13026
 	output [15:0] RDATA,
 	input         RCLK, RCLKE, RE,
 	input  [10:0] RADDR,
@@ -502,6 +633,9 @@
 endmodule
 
 module SB_RAM40_4KNR (
+	`ABC_ARRIVAL_HX(2146) // https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_hx1k.txt#L401
+	`ABC_ARRIVAL_LP(3163) // https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_lp1k.txt#L401
+	`ABC_ARRIVAL_U(1179)  // https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_up5k.txt#L13026
 	output [15:0] RDATA,
 	input         RCLKN, RCLKE, RE,
 	input  [10:0] RADDR,
@@ -567,6 +701,9 @@
 endmodule
 
 module SB_RAM40_4KNW (
+	`ABC_ARRIVAL_HX(2146) // https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_hx1k.txt#L401
+	`ABC_ARRIVAL_LP(3163) // https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_lp1k.txt#L401
+	`ABC_ARRIVAL_U(1179)  // https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_up5k.txt#L13026
 	output [15:0] RDATA,
 	input         RCLK, RCLKE, RE,
 	input  [10:0] RADDR,
@@ -632,6 +769,9 @@
 endmodule
 
 module SB_RAM40_4KNRNW (
+	`ABC_ARRIVAL_HX(2146) // https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_hx1k.txt#L401
+	`ABC_ARRIVAL_LP(3163) // https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_lp1k.txt#L401
+	`ABC_ARRIVAL_U(1179)  // https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_up5k.txt#L13026
 	output [15:0] RDATA,
 	input         RCLKN, RCLKE, RE,
 	input  [10:0] RADDR,
@@ -700,7 +840,12 @@
 
 module ICESTORM_LC (
 	input I0, I1, I2, I3, CIN, CLK, CEN, SR,
-	output LO, O, COUT
+	output LO,
+	`ABC_ARRIVAL_HX(540)
+	`ABC_ARRIVAL_LP(796)
+	`ABC_ARRIVAL_U(1391)
+	output O,
+	output COUT
 );
 	parameter [15:0] LUT_INIT = 0;
 
@@ -1300,6 +1445,7 @@
 	input ADDSUBTOP, ADDSUBBOT,
 	input OHOLDTOP, OHOLDBOT,
 	input CI, ACCUMCI, SIGNEXTIN,
+	//`ABC_ARRIVAL_U(1984)  // https://github.com/cliffordwolf/icestorm/blob/95949315364f8d9b0c693386aefadf44b28e2cf6/icefuzz/timings_up5k.txt#L13026
 	output [31:0] O,
 	output CO, ACCUMCO, SIGNEXTOUT
 );
diff --git a/techlibs/ice40/synth_ice40.cc b/techlibs/ice40/synth_ice40.cc
index c6de81b..a389026 100644
--- a/techlibs/ice40/synth_ice40.cc
+++ b/techlibs/ice40/synth_ice40.cc
@@ -238,7 +238,14 @@
 	{
 		if (check_label("begin"))
 		{
-			run("read_verilog -icells -lib +/ice40/cells_sim.v");
+			std::string define;
+			if (device_opt == "lp")
+				define = "-D ICE40_LP";
+			else if (device_opt == "u")
+				define = "-D ICE40_U";
+			else
+				define = "-D ICE40_HX";
+			run("read_verilog -icells " + define + " -lib +/ice40/cells_sim.v");
 			run(stringf("hierarchy -check %s", help_mode ? "-top <top>" : top_opt.c_str()));
 			run("proc");
 		}
diff --git a/techlibs/xilinx/Makefile.inc b/techlibs/xilinx/Makefile.inc
index 2b1af28..2efcf7d 100644
--- a/techlibs/xilinx/Makefile.inc
+++ b/techlibs/xilinx/Makefile.inc
@@ -39,6 +39,9 @@
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/lut_map.v))
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/mux_map.v))
 
+$(eval $(call add_share_file,share/xilinx,techlibs/xilinx/abc_map.v))
+$(eval $(call add_share_file,share/xilinx,techlibs/xilinx/abc_unmap.v))
+$(eval $(call add_share_file,share/xilinx,techlibs/xilinx/abc_model.v))
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/abc_xc7.box))
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/abc_xc7.lut))
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/abc_xc7_nowide.lut))
diff --git a/techlibs/xilinx/abc_map.v b/techlibs/xilinx/abc_map.v
new file mode 100644
index 0000000..0c85d66
--- /dev/null
+++ b/techlibs/xilinx/abc_map.v
@@ -0,0 +1,123 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *                2019  Eddie Hung    <eddie@fpgeh.com>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+// ============================================================================
+
+module RAM32X1D (
+  output DPO, SPO,
+  input  D,
+  input  WCLK,
+  input  WE,
+  input  A0, A1, A2, A3, A4,
+  input  DPRA0, DPRA1, DPRA2, DPRA3, DPRA4
+);
+  parameter INIT = 32'h0;
+  parameter IS_WCLK_INVERTED = 1'b0;
+  wire \$DPO , \$SPO ;
+  RAM32X1D #(
+    .INIT(INIT), .IS_WCLK_INVERTED(IS_WCLK_INVERTED)
+  ) _TECHMAP_REPLACE_ (
+    .DPO(\$DPO ), .SPO(\$SPO ),
+    .D(D), .WCLK(WCLK), .WE(WE),
+    .A0(A0), .A1(A1), .A2(A2), .A3(A3), .A4(A4),
+    .DPRA0(DPRA0), .DPRA1(DPRA1), .DPRA2(DPRA2), .DPRA3(DPRA3), .DPRA4(DPRA4)
+  );
+  \$__ABC_LUT6 dpo (.A(\$DPO ), .S({1'b0, A0, A1, A2, A3, A4}), .Y(DPO));
+  \$__ABC_LUT6 spo (.A(\$SPO ), .S({1'b0, A0, A1, A2, A3, A4}), .Y(SPO));
+endmodule
+
+module RAM64X1D (
+  output DPO, SPO,
+  input  D,
+  input  WCLK,
+  input  WE,
+  input  A0, A1, A2, A3, A4, A5,
+  input  DPRA0, DPRA1, DPRA2, DPRA3, DPRA4, DPRA5
+);
+  parameter INIT = 64'h0;
+  parameter IS_WCLK_INVERTED = 1'b0;
+  wire \$DPO , \$SPO ;
+  RAM64X1D #(
+    .INIT(INIT), .IS_WCLK_INVERTED(IS_WCLK_INVERTED)
+  ) _TECHMAP_REPLACE_ (
+    .DPO(\$DPO ), .SPO(\$SPO ),
+    .D(D), .WCLK(WCLK), .WE(WE),
+    .A0(A0), .A1(A1), .A2(A2), .A3(A3), .A4(A4), .A5(A5),
+    .DPRA0(DPRA0), .DPRA1(DPRA1), .DPRA2(DPRA2), .DPRA3(DPRA3), .DPRA4(DPRA4), .DPRA5(DPRA5)
+  );
+  \$__ABC_LUT6 dpo (.A(\$DPO ), .S({A0, A1, A2, A3, A4, A5}), .Y(DPO));
+  \$__ABC_LUT6 spo (.A(\$SPO ), .S({A0, A1, A2, A3, A4, A5}), .Y(SPO));
+endmodule
+
+module RAM128X1D (
+  output       DPO, SPO,
+  input        D,
+  input        WCLK,
+  input        WE,
+  input  [6:0] A, DPRA
+);
+  parameter INIT = 128'h0;
+  parameter IS_WCLK_INVERTED = 1'b0;
+  wire \$DPO , \$SPO ;
+  RAM128X1D #(
+    .INIT(INIT), .IS_WCLK_INVERTED(IS_WCLK_INVERTED)
+  ) _TECHMAP_REPLACE_ (
+    .DPO(\$DPO ), .SPO(\$SPO ),
+    .D(D), .WCLK(WCLK), .WE(WE),
+    .A(A),
+    .DPRA(DPRA)
+  );
+  \$__ABC_LUT7 dpo (.A(\$DPO ), .S(A), .Y(DPO));
+  \$__ABC_LUT7 spo (.A(\$SPO ), .S(A), .Y(SPO));
+endmodule
+
+module SRL16E (
+  output Q,
+  input A0, A1, A2, A3, CE, CLK, D
+);
+  parameter [15:0] INIT = 16'h0000;
+  parameter [0:0] IS_CLK_INVERTED = 1'b0;
+  wire \$Q ;
+  SRL16E #(
+    .INIT(INIT), .IS_CLK_INVERTED(IS_CLK_INVERTED)
+  ) _TECHMAP_REPLACE_ (
+    .Q(\$Q ),
+    .A0(A0), .A1(A1), .A2(A2), .A3(A3), .CE(CE), .CLK(CLK), .D(D)
+  );
+  \$__ABC_LUT6 q (.A(\$Q ), .S({1'b1, A0, A1, A2, A3, 1'b1}), .Y(Q));
+endmodule
+
+module SRLC32E (
+  output Q,
+  output Q31,
+  input [4:0] A,
+  input CE, CLK, D
+);
+  parameter [31:0] INIT = 32'h00000000;
+  parameter [0:0] IS_CLK_INVERTED = 1'b0;
+  wire \$Q ;
+  SRLC32E #(
+    .INIT(INIT), .IS_CLK_INVERTED(IS_CLK_INVERTED)
+  ) _TECHMAP_REPLACE_ (
+    .Q(\$Q ), .Q31(Q31),
+    .A(A), .CE(CE), .CLK(CLK), .D(D)
+  );
+  \$__ABC_LUT6 q (.A(\$Q ), .S({1'b1, A}), .Y(Q));
+endmodule
diff --git a/techlibs/xilinx/abc_model.v b/techlibs/xilinx/abc_model.v
new file mode 100644
index 0000000..655b993
--- /dev/null
+++ b/techlibs/xilinx/abc_model.v
@@ -0,0 +1,34 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *                2019  Eddie Hung    <eddie@fpgeh.com>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+// ============================================================================
+
+(* abc_box_id = 3, lib_whitebox *)
+module \$__XILINX_MUXF78 (output O, input I0, I1, I2, I3, S0, S1);
+  assign O = S1 ? (S0 ? I3 : I2)
+                : (S0 ? I1 : I0);
+endmodule
+
+(* abc_box_id=2000 *)
+module \$__ABC_LUT6 (input A, input [5:0] S, output Y);
+endmodule
+(* abc_box_id=2001 *)
+module \$__ABC_LUT7 (input A, input [6:0] S, output Y);
+endmodule
diff --git a/techlibs/xilinx/abc_unmap.v b/techlibs/xilinx/abc_unmap.v
new file mode 100644
index 0000000..f101a22
--- /dev/null
+++ b/techlibs/xilinx/abc_unmap.v
@@ -0,0 +1,28 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *                2019  Eddie Hung    <eddie@fpgeh.com>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+// ============================================================================
+
+module \$__ABC_LUT6 (input A, input [5:0] S, output Y);
+  assign Y = A;
+endmodule
+module \$__ABC_LUT7 (input A, input [6:0] S, output Y);
+  assign Y = A;
+endmodule
diff --git a/techlibs/xilinx/abc_xc7.box b/techlibs/xilinx/abc_xc7.box
index 3789ff3..20da3b8 100644
--- a/techlibs/xilinx/abc_xc7.box
+++ b/techlibs/xilinx/abc_xc7.box
@@ -1,4 +1,5 @@
 # Max delays from https://github.com/SymbiFlow/prjxray-db/blob/34ea6eb08a63d21ec16264ad37a0a7b142ff6031/artix7/timings/CLBLL_L.sdf
+#                 https://github.com/SymbiFlow/prjxray-db/blob/23c8b0851f979f0799318eaca90174413a46b257/artix7/timings/slicel.sdf
 
 # NB: Inputs/Outputs must be ordered alphabetically
 #     (with exceptions for carry in/out)
@@ -14,6 +15,10 @@
 MUXF8 2 1 3 1
 104 94 273
 
+# Box containing MUXF7.[AB] + MUXF8,
+#   Necessary to make these an atomic unit so that
+#   ABC cannot optimise just one of the MUXF7 away
+#   and expect to save on its delay
 # Inputs: I0 I1 I2 I3 S0 S1
 # Outputs: O
 $__MUXF78 3 1 6 1
@@ -37,22 +42,20 @@
 580 526 507 398 385 508 528 378 380 114
 
 # SLICEM/A6LUT
-# Inputs: A0 A1 A2 A3 A4 D DPRA0 DPRA1 DPRA2 DPRA3 DPRA4 WCLK WE
-# Outputs: DPO SPO
-RAM32X1D 5 0 13 2
--   -   -   -   -   - 631 472 407 238 127 - -
-631 472 407 238 127 - -   -   -   -   -   - -
+# Box to emulate comb/seq behaviour of RAMD{32,64} and SRL{16,32}
+#   Necessary since RAMD* and SRL* have both combinatorial (i.e.
+#   same-cycle read operation) and sequential (write operation
+#   is only committed on the next clock edge).
+#   To model the combinatorial path, such cells have to be split
+#   into comb and seq parts, with this box modelling only the former.
+# Inputs: A S0 S1 S2 S3 S4 S5
+# Outputs: Y
+$__ABC_LUT6 2000 0 7 1
+0 642 631 472 407 238 127
 
-# SLICEM/A6LUT
-# Inputs: A0 A1 A2 A3 A4 A5 D DPRA0 DPRA1 DPRA2 DPRA3 DPRA4 DPRA5 WCLK WE
+# SLICEM/A6LUT + F7BMUX
+# Box to emulate comb/seq behaviour of RAMD128
+# Inputs: A S0 S1 S2 S3 S4 S5 S6
 # Outputs: DPO SPO
-RAM64X1D 6 0 15 2
--   -   -   -   -   -   - 642 631 472 407 238 127 - -
-642 631 472 407 238 127 - -   -   -   -   -   -   - -
-
-# SLICEM/A6LUT + F7[AB]MUX
-# Inputs: A0 A1 A2 A3 A4 A5 A6 D DPRA0 DPRA1 DPRA2 DPRA3 DPRA4 DPRA5 DPRA6 WCLK WE
-# Outputs: DPO SPO
-RAM128X1D 7 0 17 2
--    -    -   -   -   -   -   - 1009 998 839 774 605 494 450 - -
-1047 1036 877 812 643 532 478 - -    -   -   -   -   -   -   - -
+$__ABC_LUT7 2001 0 8 1
+0 1047 1036 877 812 643 532 478
diff --git a/techlibs/xilinx/cells_map.v b/techlibs/xilinx/cells_map.v
index b8e5baf..a15884e 100644
--- a/techlibs/xilinx/cells_map.v
+++ b/techlibs/xilinx/cells_map.v
@@ -331,7 +331,6 @@
 endmodule
 `endif
 
-`ifndef _ABC
 module \$__XILINX_MUXF78 (O, I0, I1, I2, I3, S0, S1);
   output O;
   input I0, I1, I2, I3, S0, S1;
@@ -364,4 +363,3 @@
   else
     MUXF8 mux8 (.I0(T0), .I1(T1), .S(S1), .O(O));
 endmodule
-`endif
diff --git a/techlibs/xilinx/cells_sim.v b/techlibs/xilinx/cells_sim.v
index e12b77c..6e87292 100644
--- a/techlibs/xilinx/cells_sim.v
+++ b/techlibs/xilinx/cells_sim.v
@@ -184,14 +184,6 @@
   assign O = S ? I1 : I0;
 endmodule
 
-`ifdef _ABC
-(* abc_box_id = 3, lib_whitebox *)
-module \$__XILINX_MUXF78 (output O, input I0, I1, I2, I3, S0, S1);
-  assign O = S1 ? (S0 ? I3 : I2)
-                : (S0 ? I1 : I0);
-endmodule
-`endif
-
 module XORCY(output O, input CI, LI);
   assign O = CI ^ LI;
 endmodule
@@ -236,7 +228,15 @@
 
 `endif
 
-module FDRE (output reg Q, (* clkbuf_sink *) input C, input CE, D, R);
+// Max delay from: https://github.com/SymbiFlow/prjxray-db/blob/34ea6eb08a63d21ec16264ad37a0a7b142ff6031/artix7/timings/CLBLL_L.sdf#L238-L250
+
+module FDRE (
+  (* abc_arrival=303 *)
+  output reg Q,
+  (* clkbuf_sink *)
+  input C, 
+  input CE, D, R
+);
   parameter [0:0] INIT = 1'b0;
   parameter [0:0] IS_C_INVERTED = 1'b0;
   parameter [0:0] IS_D_INVERTED = 1'b0;
@@ -248,7 +248,13 @@
   endcase endgenerate
 endmodule
 
-module FDSE (output reg Q, (* clkbuf_sink *) input C, input CE, D, S);
+module FDSE (
+  (* abc_arrival=303 *)
+  output reg Q,
+  (* clkbuf_sink *)
+  input C,
+  input CE, D, S
+);
   parameter [0:0] INIT = 1'b1;
   parameter [0:0] IS_C_INVERTED = 1'b0;
   parameter [0:0] IS_D_INVERTED = 1'b0;
@@ -260,7 +266,13 @@
   endcase endgenerate
 endmodule
 
-module FDCE (output reg Q, (* clkbuf_sink *) input C, input CE, D, CLR);
+module FDCE (
+  (* abc_arrival=303 *)
+  output reg Q,
+  (* clkbuf_sink *)
+  input C,
+  input CE, D, CLR
+);
   parameter [0:0] INIT = 1'b0;
   parameter [0:0] IS_C_INVERTED = 1'b0;
   parameter [0:0] IS_D_INVERTED = 1'b0;
@@ -274,7 +286,13 @@
   endcase endgenerate
 endmodule
 
-module FDPE (output reg Q, (* clkbuf_sink *) input C, input CE, D, PRE);
+module FDPE (
+  (* abc_arrival=303 *)
+  output reg Q,
+  (* clkbuf_sink *)
+  input C,
+  input CE, D, PRE
+);
   parameter [0:0] INIT = 1'b1;
   parameter [0:0] IS_C_INVERTED = 1'b0;
   parameter [0:0] IS_D_INVERTED = 1'b0;
@@ -288,38 +306,61 @@
   endcase endgenerate
 endmodule
 
-module FDRE_1 (output reg Q, (* clkbuf_sink *) input C, input CE, D, R);
+module FDRE_1 (
+  (* abc_arrival=303 *)
+  output reg Q,
+  (* clkbuf_sink *)
+  input C,
+  input CE, D, R
+);
   parameter [0:0] INIT = 1'b0;
   initial Q <= INIT;
   always @(negedge C) if (R) Q <= 1'b0; else if(CE) Q <= D;
 endmodule
 
-module FDSE_1 (output reg Q, (* clkbuf_sink *) input C, input CE, D, S);
+module FDSE_1 (
+  (* abc_arrival=303 *)
+  output reg Q,
+  (* clkbuf_sink *)
+  input C,
+  input CE, D, S
+);
   parameter [0:0] INIT = 1'b1;
   initial Q <= INIT;
   always @(negedge C) if (S) Q <= 1'b1; else if(CE) Q <= D;
 endmodule
 
-module FDCE_1 (output reg Q, (* clkbuf_sink *) input C, input CE, D, CLR);
+module FDCE_1 (
+  (* abc_arrival=303 *)
+  output reg Q,
+  (* clkbuf_sink *)
+  input C,
+  input CE, D, CLR
+);
   parameter [0:0] INIT = 1'b0;
   initial Q <= INIT;
   always @(negedge C, posedge CLR) if (CLR) Q <= 1'b0; else if (CE) Q <= D;
 endmodule
 
-module FDPE_1 (output reg Q, (* clkbuf_sink *) input C, input CE, D, PRE);
+module FDPE_1 (
+  (* abc_arrival=303 *)
+  output reg Q,
+  (* clkbuf_sink *)
+  input C,
+  input CE, D, PRE
+);
   parameter [0:0] INIT = 1'b1;
   initial Q <= INIT;
   always @(negedge C, posedge PRE) if (PRE) Q <= 1'b1; else if (CE) Q <= D;
 endmodule
 
-(* abc_box_id = 5 *)
 module RAM32X1D (
+  // Max delay from: https://github.com/SymbiFlow/prjxray-db/blob/34ea6eb08a63d21ec16264ad37a0a7b142ff6031/artix7/timings/CLBLM_R.sdf#L957
+  (* abc_arrival=1153 *)
   output DPO, SPO,
-  (* abc_scc_break *)
   input  D,
   (* clkbuf_sink *)
   input  WCLK,
-  (* abc_scc_break *)
   input  WE,
   input  A0, A1, A2, A3, A4,
   input  DPRA0, DPRA1, DPRA2, DPRA3, DPRA4
@@ -335,14 +376,13 @@
   always @(posedge clk) if (WE) mem[a] <= D;
 endmodule
 
-(* abc_box_id = 6 *)
 module RAM64X1D (
+  // Max delay from: https://github.com/SymbiFlow/prjxray-db/blob/34ea6eb08a63d21ec16264ad37a0a7b142ff6031/artix7/timings/CLBLM_R.sdf#L957
+  (* abc_arrival=1153 *)
   output DPO, SPO,
-  (* abc_scc_break *)
   input  D,
   (* clkbuf_sink *)
   input  WCLK,
-  (* abc_scc_break *)
   input  WE,
   input  A0, A1, A2, A3, A4, A5,
   input  DPRA0, DPRA1, DPRA2, DPRA3, DPRA4, DPRA5
@@ -358,14 +398,13 @@
   always @(posedge clk) if (WE) mem[a] <= D;
 endmodule
 
-(* abc_box_id = 7 *)
 module RAM128X1D (
-  output       DPO, SPO,
-  (* abc_scc_break *)
+  // Max delay from: https://github.com/SymbiFlow/prjxray-db/blob/34ea6eb08a63d21ec16264ad37a0a7b142ff6031/artix7/timings/CLBLM_R.sdf#L957
+  (* abc_arrival=1153 *)
+  output DPO, SPO,
   input        D,
   (* clkbuf_sink *)
   input        WCLK,
-  (* abc_scc_break *)
   input        WE,
   input  [6:0] A, DPRA
 );
@@ -379,6 +418,8 @@
 endmodule
 
 module SRL16E (
+  // Max delay from: https://github.com/SymbiFlow/prjxray-db/blob/34ea6eb08a63d21ec16264ad37a0a7b142ff6031/artix7/timings/CLBLM_R.sdf#L904-L905
+  (* abc_arrival=1472 *)
   output Q,
   input A0, A1, A2, A3, CE,
   (* clkbuf_sink *)
@@ -423,7 +464,10 @@
 endmodule
 
 module SRLC32E (
+  // Max delay from: https://github.com/SymbiFlow/prjxray-db/blob/34ea6eb08a63d21ec16264ad37a0a7b142ff6031/artix7/timings/CLBLM_R.sdf#L904-L905
+  (* abc_arrival=1472 *)
   output Q,
+  (* abc_arrival=1114 *)
   output Q31,
   input [4:0] A,
   input CE,
diff --git a/techlibs/xilinx/synth_xilinx.cc b/techlibs/xilinx/synth_xilinx.cc
index 3760a11..bfc0ac2 100644
--- a/techlibs/xilinx/synth_xilinx.cc
+++ b/techlibs/xilinx/synth_xilinx.cc
@@ -268,9 +268,9 @@
 	{
 		if (check_label("begin")) {
 			if (vpr)
-				run("read_verilog -lib -icells -D _ABC -D_EXPLICIT_CARRY +/xilinx/cells_sim.v");
+				run("read_verilog -lib -D_EXPLICIT_CARRY +/xilinx/cells_sim.v");
 			else
-				run("read_verilog -lib -icells -D _ABC +/xilinx/cells_sim.v");
+				run("read_verilog -lib +/xilinx/cells_sim.v");
 
 			run("read_verilog -lib +/xilinx/cells_xtra.v");
 
@@ -408,7 +408,7 @@
 		}
 
 		if (check_label("map_cells")) {
-			std::string techmap_args = "-map +/techmap.v -D _ABC -map +/xilinx/cells_map.v";
+			std::string techmap_args = "-map +/techmap.v -map +/xilinx/cells_map.v";
 			if (widemux > 0)
 				techmap_args += stringf(" -D MIN_MUX_INPUTS=%d", widemux);
 			run("techmap " + techmap_args);
@@ -428,10 +428,12 @@
 			if (flatten_before_abc)
 				run("flatten");
 			if (help_mode)
-				run("abc -luts 2:2,3,6:5[,10,20] [-dff]", "(option for 'nowidelut', option for '-retime')");
+				run("abc -luts 2:2,3,6:5[,10,20] [-dff]", "(option for 'nowidelut'; option for '-retime')");
 			else if (abc9) {
 				if (family != "xc7")
 					log_warning("'synth_xilinx -abc9' currently supports '-family xc7' only.\n");
+				run("techmap -map +/xilinx/abc_map.v -max_iter 1");
+				run("read_verilog -icells -lib +/xilinx/abc_model.v");
 				if (nowidelut)
 					run("abc9 -lut +/xilinx/abc_xc7_nowide.lut -box +/xilinx/abc_xc7.box -W " + std::to_string(XC7_WIRE_DELAY));
 				else
@@ -449,14 +451,15 @@
 			//   has performed any necessary retiming
 			if (!nosrl || help_mode)
 				run("xilinx_srl -fixed -minlen 3", "(skip if '-nosrl')");
-
 			std::string techmap_args = "-map +/xilinx/lut_map.v -map +/xilinx/cells_map.v";
 			if (help_mode)
-					techmap_args += " [-map +/xilinx/ff_map.v]";
-			else if (!abc9)
-					techmap_args += " -map +/xilinx/ff_map.v";
+				techmap_args += " [-map +/xilinx/ff_map.v]";
+			else if (abc9)
+				techmap_args += " -map +/xilinx/abc_unmap.v";
+			else
+				techmap_args += " -map +/xilinx/ff_map.v";
 			run("techmap " + techmap_args);
-			if (!abc9)
+			if (!abc9 || help_mode)
 				run("dffinit -ff FDRE Q INIT -ff FDCE Q INIT -ff FDPE Q INIT -ff FDSE Q INIT "
 						"-ff FDRE_1 Q INIT -ff FDCE_1 Q INIT -ff FDPE_1 Q INIT -ff FDSE_1 Q INIT", "(without '-abc9' only)");
 			run("clean");
diff --git a/techlibs/xilinx/xc7_brams_bb.v b/techlibs/xilinx/xc7_brams_bb.v
index a43b4b5..5b40a45 100644
--- a/techlibs/xilinx/xc7_brams_bb.v
+++ b/techlibs/xilinx/xc7_brams_bb.v
@@ -1,3 +1,5 @@
+// Max delays from https://github.com/SymbiFlow/prjxray-db/blob/f8e0364116b2983ac72a3dc8c509ea1cc79e2e3d/artix7/timings/BRAM_L.sdf#L138-L147
+
 module RAMB18E1 (
 	(* clkbuf_sink *)
 	input CLKARDCLK,
@@ -21,9 +23,13 @@
 	input [1:0] WEA,
 	input [3:0] WEBWE,
 
+	(* abc_arrival=2454 *)
 	output [15:0] DOADO,
+	(* abc_arrival=2454 *)
 	output [15:0] DOBDO,
+	(* abc_arrival=2454 *)
 	output [1:0] DOPADOP,
+	(* abc_arrival=2454 *)
 	output [1:0] DOPBDOP
 );
 	parameter INITP_00 = 256'h0000000000000000000000000000000000000000000000000000000000000000;
@@ -147,9 +153,13 @@
 	input [3:0] WEA,
 	input [7:0] WEBWE,
 
+	(* abc_arrival=2454 *)
 	output [31:0] DOADO,
+	(* abc_arrival=2454 *)
 	output [31:0] DOBDO,
+	(* abc_arrival=2454 *)
 	output [3:0] DOPADOP,
+	(* abc_arrival=2454 *)
 	output [3:0] DOPBDOP
 );
 	parameter INITP_00 = 256'h0000000000000000000000000000000000000000000000000000000000000000;
diff --git a/tests/various/abc9.v b/tests/various/abc9.v
index a08b613..30ebd4e 100644
--- a/tests/various/abc9.v
+++ b/tests/various/abc9.v
@@ -5,5 +5,7 @@
 endmodule
 
 module abc9_test028(input i, output o);
-unknown u(~i, o);
+wire w;
+unknown u(~i, w);
+unknown2 u2(w, o);
 endmodule