Merge remote-tracking branch 'origin/master' into xaig_dff

92 files changed, 3030 insertions, 848 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 44e32c6a8..5535ce418 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -3,6 +3,17 @@ List of major changes and improvements between releases
 =======================================================
 
 
+Yosys 0.9 .. Yosys 0.9-dev
+--------------------------
+
+ * Various
+    - Added "write_xaiger" backend
+    - Added "abc9" pass for timing-aware techmapping (experimental, FPGA only, no FFs)
+    - Added "synth_xilinx -abc9" (experimental)
+    - Added "synth_ice40 -abc9" (experimental)
+    - Added "synth -abc9" (experimental)
+
+
 Yosys 0.8 .. Yosys 0.8-dev
 --------------------------
 
@@ -16,12 +27,18 @@ Yosys 0.8 .. Yosys 0.8-dev
     - Added "gate2lut.v" techmap rule
     - Added "rename -src"
     - Added "equiv_opt" pass
+    - Added "shregmap -tech xilinx"
     - Added "read_aiger" frontend
-    - Added "abc9" pass for timing-aware techmapping (experimental, FPGA only, no FFs)
-    - Added "synth_xilinx -abc9" (experimental)
-    - Added "synth_ice40 -abc9" (experimental)
-    - Added "synth -abc9" (experimental)
-    - "synth_xilinx" to now infer hard shift registers, using new "shregmap -tech xilinx"
+    - Added "muxcover -mux{4,8,16}=<cost>"
+    - Added "muxcover -dmux=<cost>"
+    - Added "muxcover -nopartial"
+    - Added "muxpack" pass
+    - Added "pmux2shiftx -norange"
+    - Added "synth_xilinx -nocarry"
+    - Added "synth_xilinx -nowidelut"
+    - Added "synth_ecp5 -nowidelut"
+    - "synth_xilinx" to now infer hard shift registers (-nosrl to disable)
+    - Fixed sign extension of unsized constants with 'bx and 'bz MSB
 
 
 Yosys 0.7 .. Yosys 0.8
@@ -35,7 +52,7 @@ Yosys 0.7 .. Yosys 0.8
     - Added "write_verilog -decimal"
     - Added "scc -set_attr"
     - Added "verilog_defines" command
-    - Remeber defines from one read_verilog to next
+    - Remember defines from one read_verilog to next
     - Added support for hierarchical defparam
     - Added FIRRTL back-end
     - Improved ABC default scripts
@@ -44,7 +61,7 @@ Yosys 0.7 .. Yosys 0.8
     - Added Verilog $rtoi and $itor support
     - Added "check -initdrv"
     - Added "read_blif -wideports"
-    - Added support for systemVerilog "++" and "--" operators
+    - Added support for SystemVerilog "++" and "--" operators
     - Added support for SystemVerilog unique, unique0, and priority case
     - Added "write_edif" options for edif "flavors"
     - Added support for resetall compiler directive
diff --git a/Makefile b/Makefile
index fb0eaf14d..d33f27b63 100644
--- a/Makefile
+++ b/Makefile
@@ -666,6 +666,12 @@ else
 SEEDOPT=""
 endif
 
+ifneq ($(ABCEXTERNAL),)
+ABCOPT="-A $(ABCEXTERNAL)"
+else
+ABCOPT=""
+endif
+
 test: $(TARGETS) $(EXTRA_TARGETS)
 	+cd tests/simple && bash run-test.sh $(SEEDOPT)
 	+cd tests/hana && bash run-test.sh $(SEEDOPT)
@@ -674,13 +680,15 @@ test: $(TARGETS) $(EXTRA_TARGETS)
 	+cd tests/share && bash run-test.sh $(SEEDOPT)
 	+cd tests/fsm && bash run-test.sh $(SEEDOPT)
 	+cd tests/techmap && bash run-test.sh
-	+cd tests/memories && bash run-test.sh $(SEEDOPT)
+	+cd tests/memories && bash run-test.sh $(ABCOPT) $(SEEDOPT)
 	+cd tests/bram && bash run-test.sh $(SEEDOPT)
 	+cd tests/various && bash run-test.sh
 	+cd tests/sat && bash run-test.sh
 	+cd tests/svinterfaces && bash run-test.sh $(SEEDOPT)
 	+cd tests/opt && bash run-test.sh
-	+cd tests/aiger && bash run-test.sh
+	+cd tests/aiger && bash run-test.sh $(ABCOPT)
+	+cd tests/arch && bash run-test.sh
+	+cd tests/simple_abc9 && bash run-test.sh $(SEEDOPT)
 	@echo ""
 	@echo "  Passed \"make test\"."
 	@echo ""
diff --git a/README.md b/README.md
index 94ea9538f..42f972c8e 100644
--- a/README.md
+++ b/README.md
@@ -350,6 +350,14 @@ Verilog Attributes and non-standard features
   through the synthesis. When entities are combined, a new |-separated
   string is created that contains all the string from the original entities.
 
+- The ``defaultvalue`` attribute is used to store default values for
+  module inputs. The attribute is attached to the input wire by the HDL
+  front-end when the input is declared with a default value.
+
+- The ``parameter`` and ``localparam`` attributes are used to mark wires
+  that represent module parameters or localparams (when the HDL front-end
+  is run in -pwires mode).
+
 - 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/aiger.cc b/backends/aiger/aiger.cc
index 516e538a5..7c851bb91 100644
--- a/backends/aiger/aiger.cc
+++ b/backends/aiger/aiger.cc
@@ -70,34 +70,35 @@ struct AigerWriter
 
 	int bit2aig(SigBit bit)
 	{
-		if (aig_map.count(bit) == 0)
-		{
-			aig_map[bit] = -1;
-
-			if (initstate_bits.count(bit)) {
-				log_assert(initstate_ff > 0);
-				aig_map[bit] = initstate_ff;
-			} else
-			if (not_map.count(bit)) {
-				int a = bit2aig(not_map.at(bit)) ^ 1;
-				aig_map[bit] = a;
-			} else
-			if (and_map.count(bit)) {
-				auto args = and_map.at(bit);
-				int a0 = bit2aig(args.first);
-				int a1 = bit2aig(args.second);
-				aig_map[bit] = mkgate(a0, a1);
-			} else
-			if (alias_map.count(bit)) {
-				aig_map[bit] = bit2aig(alias_map.at(bit));
-			}
+		auto it = aig_map.find(bit);
+		if (it != aig_map.end()) {
+			log_assert(it->second >= 0);
+			return it->second;
+		}
 
-			if (bit == State::Sx || bit == State::Sz)
-				log_error("Design contains 'x' or 'z' bits. Use 'setundef' to replace those constants.\n");
+		// NB: Cannot use iterator returned from aig_map.insert()
+		//     since this function is called recursively
+
+		int a = -1;
+		if (not_map.count(bit)) {
+			a = bit2aig(not_map.at(bit)) ^ 1;
+		} else
+		if (and_map.count(bit)) {
+			auto args = and_map.at(bit);
+			int a0 = bit2aig(args.first);
+			int a1 = bit2aig(args.second);
+			a = mkgate(a0, a1);
+		} else
+		if (alias_map.count(bit)) {
+			a = bit2aig(alias_map.at(bit));
 		}
 
-		log_assert(aig_map.at(bit) >= 0);
-		return aig_map.at(bit);
+		if (bit == State::Sx || bit == State::Sz)
+			log_error("Design contains 'x' or 'z' bits. Use 'setundef' to replace those constants.\n");
+
+		log_assert(a >= 0);
+		aig_map[bit] = a;
+		return a;
 	}
 
 	AigerWriter(Module *module, bool zinit_mode, bool imode, bool omode, bool bmode) : module(module), zinit_mode(zinit_mode), sigmap(module)
@@ -776,6 +777,7 @@ struct AigerBackend : public Backend {
 		writer.write_aiger(*f, ascii_mode, miter_mode, symbols_mode);
 
 		if (!map_filename.empty()) {
+			rewrite_filename(filename);
 			std::ofstream mapf;
 			mapf.open(map_filename.c_str(), std::ofstream::trunc);
 			if (mapf.fail())
diff --git a/backends/aiger/xaiger.cc b/backends/aiger/xaiger.cc
index 87dca014d..8a35e06fa 100644
--- a/backends/aiger/xaiger.cc
+++ b/backends/aiger/xaiger.cc
@@ -25,6 +25,21 @@
 #elif defined(__APPLE__)
 #include <libkern/OSByteOrder.h>
 #define __builtin_bswap32 OSSwapInt32
+#elif !defined(__GNUC__)
+#include <cstdint>
+inline uint32_t __builtin_bswap32(uint32_t x)
+{
+	// https://stackoverflow.com/a/27796212
+	register uint32_t value = number_to_be_reversed;
+	uint8_t lolo = (value >> 0) & 0xFF;
+	uint8_t lohi = (value >> 8) & 0xFF;
+	uint8_t hilo = (value >> 16) & 0xFF;
+	uint8_t hihi = (value >> 24) & 0xFF;
+	return (hihi << 24)
+		| (hilo << 16)
+		| (lohi << 8)
+		| (lolo << 0);
+}
 #endif
 
 #include "kernel/yosys.h"
@@ -79,6 +94,7 @@ struct XAigerWriter
 	dict<SigBit, int> ordered_latches;
 
 	vector<Cell*> box_list;
+	bool omode = false;
 
 	//dict<SigBit, int> init_inputs;
 	//int initstate_ff = 0;
@@ -92,30 +108,37 @@ struct XAigerWriter
 
 	int bit2aig(SigBit bit)
 	{
-		if (aig_map.count(bit) == 0)
-		{
-			aig_map[bit] = -1;
-
-			if (not_map.count(bit)) {
-				int a = bit2aig(not_map.at(bit)) ^ 1;
-				aig_map[bit] = a;
-			} else
-			if (and_map.count(bit)) {
-				auto args = and_map.at(bit);
-				int a0 = bit2aig(args.first);
-				int a1 = bit2aig(args.second);
-				aig_map[bit] = mkgate(a0, a1);
-			} else
-			if (alias_map.count(bit)) {
-				aig_map[bit] = bit2aig(alias_map.at(bit));
-			}
+		auto it = aig_map.find(bit);
+		if (it != aig_map.end()) {
+			log_assert(it->second >= 0);
+			return it->second;
+		}
+
+		// NB: Cannot use iterator returned from aig_map.insert()
+		//     since this function is called recursively
+
+		int a = -1;
+		if (not_map.count(bit)) {
+			a = bit2aig(not_map.at(bit)) ^ 1;
+		} else
+		if (and_map.count(bit)) {
+			auto args = and_map.at(bit);
+			int a0 = bit2aig(args.first);
+			int a1 = bit2aig(args.second);
+			a = mkgate(a0, a1);
+		} else
+		if (alias_map.count(bit)) {
+			a = bit2aig(alias_map.at(bit));
+		}
 
-			if (bit == State::Sx || bit == State::Sz)
-				log_error("Design contains 'x' or 'z' bits. Use 'setundef' to replace those constants.\n");
+		if (bit == State::Sx || bit == State::Sz) {
+			log_debug("Design contains 'x' or 'z' bits. Treating as 1'b0.\n");
+			a = aig_map.at(State::S0);
 		}
 
-		log_assert(aig_map.at(bit) >= 0);
-		return aig_map.at(bit);
+		log_assert(a >= 0);
+		aig_map[bit] = a;
+		return a;
 	}
 
 	XAigerWriter(Module *module, bool zinit_mode, bool holes_mode=false) : module(module), zinit_mode(zinit_mode), sigmap(module)
@@ -167,9 +190,13 @@ struct XAigerWriter
 				}
 
 				if (wire->port_output || keep) {
-					if (bit != wirebit)
-						alias_map[wirebit] = bit;
-					output_bits.insert(wirebit);
+					if (bit != RTLIL::Sx) {
+						if (bit != wirebit)
+							alias_map[wirebit] = bit;
+						output_bits.insert(wirebit);
+					}
+					else
+						log_debug("Skipping PO '%s' driven by 1'bx\n", log_signal(wirebit));
 				}
 			}
 		}
@@ -274,7 +301,8 @@ struct XAigerWriter
 					if (c.second.is_fully_const()) continue;
 					auto is_input = cell->input(c.first);
 					auto is_output = cell->output(c.first);
-					log_assert(is_input || is_output);
+					if (!is_input && !is_output)
+						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()) {
@@ -313,8 +341,6 @@ struct XAigerWriter
 					for (auto user_cell : it.second)
 						toposort.edge(driver_cell, user_cell);
 
-			pool<RTLIL::Module*> abc_carry_modules;
-
 #if 0
 			toposort.analyze_loops = true;
 #endif
@@ -322,53 +348,63 @@ struct XAigerWriter
 #if 0
 			unsigned i = 0;
 			for (auto &it : toposort.loops) {
-				log("  loop %d", i++);
-				for (auto cell : it)
-					log(" %s", log_id(cell));
-				log("\n");
+				log("  loop %d\n", i++);
+				for (auto cell_name : it) {
+					auto cell = module->cell(cell_name);
+					log_assert(cell);
+					log("\t%s (%s @ %s)\n", log_id(cell), log_id(cell->type), cell->get_src_attribute().c_str());
+				}
 			}
 #endif
 			log_assert(no_loops);
 
+			pool<IdString> seen_boxes;
 			for (auto cell_name : toposort.sorted) {
 				RTLIL::Cell *cell = module->cell(cell_name);
+				log_assert(cell);
+
 				RTLIL::Module* box_module = module->design->module(cell->type);
 				if (!box_module || !box_module->attributes.count("\\abc_box_id"))
 					continue;
 
-				if (box_module->attributes.count("\\abc_carry") && !abc_carry_modules.count(box_module)) {
-					RTLIL::Wire* carry_in = nullptr, *carry_out = nullptr;
-					RTLIL::Wire* last_in = nullptr, *last_out = nullptr;
-					for (const auto &port_name : box_module->ports) {
-						RTLIL::Wire* w = box_module->wire(port_name);
-						log_assert(w);
-						if (w->port_input) {
-							if (w->attributes.count("\\abc_carry_in")) {
-								log_assert(!carry_in);
-								carry_in = w;
-							}
-							log_assert(!last_in || last_in->port_id < w->port_id);
-							last_in = w;
-						}
-						if (w->port_output) {
-							if (w->attributes.count("\\abc_carry_out")) {
-								log_assert(!carry_out);
-								carry_out = w;
+				if (seen_boxes.insert(cell->type).second) {
+					auto it = box_module->attributes.find("\\abc_carry");
+					if (it != box_module->attributes.end()) {
+						RTLIL::Wire *carry_in = nullptr, *carry_out = nullptr;
+						auto carry_in_out = it->second.decode_string();
+						auto pos = carry_in_out.find(',');
+						if (pos == std::string::npos)
+							log_error("'abc_carry' attribute on module '%s' does not contain ','.\n", log_id(cell->type));
+						auto carry_in_name = RTLIL::escape_id(carry_in_out.substr(0, pos));
+						carry_in = box_module->wire(carry_in_name);
+						if (!carry_in || !carry_in->port_input)
+							log_error("'abc_carry' on module '%s' contains '%s' which does not exist or is not an input port.\n", log_id(cell->type), carry_in_name.c_str());
+
+						auto carry_out_name = RTLIL::escape_id(carry_in_out.substr(pos+1));
+						carry_out = box_module->wire(carry_out_name);
+						if (!carry_out || !carry_out->port_output)
+							log_error("'abc_carry' on module '%s' contains '%s' which does not exist or is not an output port.\n", log_id(cell->type), carry_out_name.c_str());
+
+						auto &ports = box_module->ports;
+						for (auto jt = ports.begin(); jt != ports.end(); ) {
+							RTLIL::Wire* w = box_module->wire(*jt);
+							log_assert(w);
+							if (w == carry_in || w == carry_out) {
+								jt = ports.erase(jt);
+								continue;
 							}
-							log_assert(!last_out || last_out->port_id < w->port_id);
-							last_out = w;
+							if (w->port_id > carry_in->port_id)
+								--w->port_id;
+							if (w->port_id > carry_out->port_id)
+								--w->port_id;
+							log_assert(w->port_input || w->port_output);
+							log_assert(ports[w->port_id-1] == w->name);
+							++jt;
 						}
-					}
-
-					if (carry_in) {
-						log_assert(last_in);
-						std::swap(box_module->ports[carry_in->port_id-1], box_module->ports[last_in->port_id-1]);
-						std::swap(carry_in->port_id, last_in->port_id);
-					}
-					if (carry_out) {
-						log_assert(last_out);
-						std::swap(box_module->ports[carry_out->port_id-1], box_module->ports[last_out->port_id-1]);
-						std::swap(carry_out->port_id, last_out->port_id);
+						ports.push_back(carry_in->name);
+						carry_in->port_id = ports.size();
+						ports.push_back(carry_out->name);
+						carry_out->port_id = ports.size();
 					}
 				}
 
@@ -393,10 +429,16 @@ struct XAigerWriter
 						}
 
 						int offset = 0;
-						for (const auto &b : rhs.bits()) {
+						for (auto b : rhs.bits()) {
 							SigBit I = sigmap(b);
-							if (I != b)
-								alias_map[b] = I;
+							if (b == RTLIL::Sx)
+								b = RTLIL::S0;
+							else if (I != b) {
+								if (I == RTLIL::Sx)
+									alias_map[b] = RTLIL::S0;
+								else
+									alias_map[b] = I;
+							}
 							co_bits.emplace_back(b, cell, port_name, offset++, 0);
 							unused_bits.erase(b);
 						}
@@ -437,27 +479,33 @@ struct XAigerWriter
 		}
 
 		for (auto bit : input_bits) {
+			if (!output_bits.count(bit))
+				continue;
 			RTLIL::Wire *wire = bit.wire;
 			// If encountering an inout port, or a keep-ed wire, then create a new wire
 			// with $inout.out suffix, make it a PO driven by the existing inout, and
 			// inherit existing inout's drivers
 			if ((wire->port_input && wire->port_output && !undriven_bits.count(bit))
 					|| wire->attributes.count("\\keep")) {
-				log_assert(input_bits.count(bit) && output_bits.count(bit));
 				RTLIL::IdString wire_name = wire->name.str() + "$inout.out";
 				RTLIL::Wire *new_wire = module->wire(wire_name);
 				if (!new_wire)
 					new_wire = module->addWire(wire_name, GetSize(wire));
 				SigBit new_bit(new_wire, bit.offset);
 				module->connect(new_bit, bit);
-				if (not_map.count(bit))
-					not_map[new_bit] = not_map.at(bit);
-				else if (and_map.count(bit))
-					and_map[new_bit] = and_map.at(bit);
-				else if (alias_map.count(bit))
-					alias_map[new_bit] = alias_map.at(bit);
+				if (not_map.count(bit)) {
+					auto a = not_map.at(bit);
+					not_map[new_bit] = a;
+				}
+				else if (and_map.count(bit)) {
+					auto a = and_map.at(bit);
+					and_map[new_bit] = a;
+				}
+				else if (alias_map.count(bit)) {
+					auto a = alias_map.at(bit);
+					alias_map[new_bit] = a;
+				}
 				else
-					//log_abort();
 					alias_map[new_bit] = bit;
 				output_bits.erase(bit);
 				output_bits.insert(new_bit);
@@ -590,6 +638,12 @@ struct XAigerWriter
 			aig_o++;
 			aig_outputs.push_back(ff_aig_map.at(bit));
 		}
+
+		if (output_bits.empty()) {
+			aig_o++;
+			aig_outputs.push_back(0);
+			omode = true;
+        }
 	}
 
 	void write_aiger(std::ostream &f, bool ascii_mode)
@@ -796,6 +850,8 @@ struct XAigerWriter
 			f.write(buffer_str.data(), buffer_str.size());
 
 			if (holes_module) {
+				log_push();
+
 				// NB: fixup_ports() will sort ports by name
 				//holes_module->fixup_ports();
 				holes_module->check();
@@ -832,6 +888,8 @@ struct XAigerWriter
 				f.write(reinterpret_cast<const char*>(&buffer_size_be), sizeof(buffer_size_be));
 				f.write(buffer_str.data(), buffer_str.size());
 				holes_module->design->remove(holes_module);
+
+				log_pop();
 			}
 		}
 
@@ -915,6 +973,8 @@ struct XAigerWriter
 		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";
 
 		latch_lines.sort();
 		for (auto &it : latch_lines)
diff --git a/backends/btor/btor.cc b/backends/btor/btor.cc
index 511a11942..a507b120b 100644
--- a/backends/btor/btor.cc
+++ b/backends/btor/btor.cc
@@ -17,6 +17,11 @@
  *
  */
 
+// [[CITE]] Btor2 , BtorMC and Boolector 3.0
+// Aina Niemetz, Mathias Preiner, Clifford Wolf, Armin Biere
+// Computer Aided Verification - 30th International Conference, CAV 2018
+// https://cs.stanford.edu/people/niemetz/publication/2018/niemetzpreinerwolfbiere-cav18/
+
 #include "kernel/rtlil.h"
 #include "kernel/register.h"
 #include "kernel/sigtools.h"
@@ -875,9 +880,28 @@ struct BtorWorker
 					else
 					{
 						if (bit_cell.count(bit) == 0)
-							log_error("No driver for signal bit %s.\n", log_signal(bit));
-						export_cell(bit_cell.at(bit));
-						log_assert(bit_nid.count(bit));
+						{
+							SigSpec s = bit;
+
+							while (i+GetSize(s) < GetSize(sig) && sig[i+GetSize(s)].wire != nullptr &&
+									bit_cell.count(sig[i+GetSize(s)]) == 0)
+								s.append(sig[i+GetSize(s)]);
+
+							log_warning("No driver for signal %s.\n", log_signal(s));
+
+							int sid = get_bv_sid(GetSize(s));
+							int nid = next_nid++;
+							btorf("%d input %d %s\n", nid, sid);
+							nid_width[nid] = GetSize(s);
+
+							i += GetSize(s)-1;
+							continue;
+						}
+						else
+						{
+							export_cell(bit_cell.at(bit));
+							log_assert(bit_nid.count(bit));
+						}
 					}
 				}
 
diff --git a/backends/ilang/ilang_backend.cc b/backends/ilang/ilang_backend.cc
index 04d1ee311..b4ba2b03f 100644
--- a/backends/ilang/ilang_backend.cc
+++ b/backends/ilang/ilang_backend.cc
@@ -483,6 +483,7 @@ struct DumpPass : public Pass {
 		std::stringstream buf;
 
 		if (!filename.empty()) {
+			rewrite_filename(filename);
 			std::ofstream *ff = new std::ofstream;
 			ff->open(filename.c_str(), append ? std::ofstream::app : std::ofstream::trunc);
 			if (ff->fail()) {
diff --git a/backends/json/json.cc b/backends/json/json.cc
index f5c687981..dda4dfedd 100644
--- a/backends/json/json.cc
+++ b/backends/json/json.cc
@@ -126,6 +126,10 @@ struct JsonWriter
 			f << stringf("%s\n", first ? "" : ",");
 			f << stringf("        %s: {\n", get_name(n).c_str());
 			f << stringf("          \"direction\": \"%s\",\n", w->port_input ? w->port_output ? "inout" : "input" : "output");
+			if (w->start_offset)
+				f << stringf("          \"offset\": %d,\n", w->start_offset);
+			if (w->upto)
+				f << stringf("          \"upto\": 1,\n");
 			f << stringf("          \"bits\": %s\n", get_bits(w).c_str());
 			f << stringf("        }");
 			first = false;
@@ -189,6 +193,10 @@ struct JsonWriter
 			f << stringf("        %s: {\n", get_name(w->name).c_str());
 			f << stringf("          \"hide_name\": %s,\n", w->name[0] == '$' ? "1" : "0");
 			f << stringf("          \"bits\": %s,\n", get_bits(w).c_str());
+			if (w->start_offset)
+				f << stringf("          \"offset\": %d,\n", w->start_offset);
+			if (w->upto)
+				f << stringf("          \"upto\": 1,\n");
 			f << stringf("          \"attributes\": {");
 			write_parameters(w->attributes);
 			f << stringf("\n          }\n");
@@ -525,6 +533,7 @@ struct JsonPass : public Pass {
 		std::stringstream buf;
 
 		if (!filename.empty()) {
+			rewrite_filename(filename);
 			std::ofstream *ff = new std::ofstream;
 			ff->open(filename.c_str(), std::ofstream::trunc);
 			if (ff->fail()) {
diff --git a/backends/protobuf/protobuf.cc b/backends/protobuf/protobuf.cc
index 549fc73ae..fff110bb0 100644
--- a/backends/protobuf/protobuf.cc
+++ b/backends/protobuf/protobuf.cc
@@ -336,6 +336,7 @@ struct ProtobufPass : public Pass {
 		std::stringstream buf;
 
 		if (!filename.empty()) {
+			rewrite_filename(filename);
 			std::ofstream *ff = new std::ofstream;
 			ff->open(filename.c_str(), std::ofstream::trunc);
 			if (ff->fail()) {
diff --git a/backends/smt2/smtio.py b/backends/smt2/smtio.py
index ab20a4af2..ae7968a1b 100644
--- a/backends/smt2/smtio.py
+++ b/backends/smt2/smtio.py
@@ -1023,6 +1023,8 @@ class MkVcd:
         assert t >= self.t
         if t != self.t:
             if self.t == -1:
+                print("$version Generated by Yosys-SMTBMC $end", file=self.f)
+                print("$timescale 1ns $end", file=self.f)
                 print("$var integer 32 t smt_step $end", file=self.f)
                 print("$var event 1 ! smt_clock $end", file=self.f)
 
@@ -1041,7 +1043,10 @@ class MkVcd:
                         scope = scope[:-1]
 
                     while uipath[:-1] != scope:
-                        print("$scope module %s $end" % uipath[len(scope)], file=self.f)
+                        scopename = uipath[len(scope)]
+                        if scopename.startswith("$"):
+                            scopename = "\\" + scopename
+                        print("$scope module %s $end" % scopename, file=self.f)
                         scope.append(uipath[len(scope)])
 
                     if path in self.clocks and self.clocks[path][1] == "event":
diff --git a/frontends/aiger/aigerparse.cc b/frontends/aiger/aigerparse.cc
index 60cbde857..7f81a4c89 100644
--- a/frontends/aiger/aigerparse.cc
+++ b/frontends/aiger/aigerparse.cc
@@ -22,9 +22,6 @@
 // Armin Biere. The AIGER And-Inverter Graph (AIG) Format Version 20071012. Technical Report 07/1, October 2011, FMV Reports Series, Institute for Formal Models and Verification, Johannes Kepler University, Altenbergerstr. 69, 4040 Linz, Austria.
 // http://fmv.jku.at/papers/Biere-FMV-TR-07-1.pdf
 
-#ifdef _WIN32
-#include <libgen.h>
-#endif
 // https://stackoverflow.com/a/46137633
 #ifdef _MSC_VER
 #include <stdlib.h>
@@ -52,6 +49,9 @@ inline int32_t from_big_endian(int32_t i32) {
 #endif
 }
 
+#define log_debug2(...) ;
+//#define log_debug2(...) log_debug(__VA_ARGS__)
+
 struct ConstEvalAig
 {
 	RTLIL::Module *module;
@@ -117,13 +117,20 @@ struct ConstEvalAig
 
 		RTLIL::Cell *cell = sig2driver.at(output);
 		RTLIL::SigBit sig_a = cell->getPort("\\A");
+		sig2deps[sig_a].reserve(sig2deps[sig_a].size() + sig2deps[output].size()); // Reserve so that any invalidation
+											   // that may occur does so here, and
+											   // not mid insertion (below)
 		sig2deps[sig_a].insert(sig2deps[output].begin(), sig2deps[output].end());
 		if (!inputs.count(sig_a))
 			compute_deps(sig_a, inputs);
 
 		if (cell->type == "$_AND_") {
 			RTLIL::SigSpec sig_b = cell->getPort("\\B");
+			sig2deps[sig_b].reserve(sig2deps[sig_b].size() + sig2deps[output].size()); // Reserve so that any invalidation
+												   // that may occur does so here, and
+												   // not mid insertion (below)
 			sig2deps[sig_b].insert(sig2deps[output].begin(), sig2deps[output].end());
+
 			if (!inputs.count(sig_b))
 				compute_deps(sig_b, inputs);
 		}
@@ -305,7 +312,7 @@ static RTLIL::Wire* createWireIfNotExists(RTLIL::Module *module, unsigned litera
 	RTLIL::IdString wire_name(stringf("\\__%d%s__", variable, invert ? "b" : ""));
 	RTLIL::Wire *wire = module->wire(wire_name);
 	if (wire) return wire;
-	log_debug("Creating %s\n", wire_name.c_str());
+	log_debug2("Creating %s\n", wire_name.c_str());
 	wire = module->addWire(wire_name);
 	wire->port_input = wire->port_output = false;
 	if (!invert) return wire;
@@ -315,12 +322,12 @@ static RTLIL::Wire* createWireIfNotExists(RTLIL::Module *module, unsigned litera
 		if (module->cell(wire_inv_name)) return wire;
 	}
 	else {
-		log_debug("Creating %s\n", wire_inv_name.c_str());
+		log_debug2("Creating %s\n", wire_inv_name.c_str());
 		wire_inv = module->addWire(wire_inv_name);
 		wire_inv->port_input = wire_inv->port_output = false;
 	}
 
-	log_debug("Creating %s = ~%s\n", wire_name.c_str(), wire_inv_name.c_str());
+	log_debug2("Creating %s = ~%s\n", wire_name.c_str(), wire_inv_name.c_str());
 	module->addNotGate(stringf("\\__%d__$not", variable), wire_inv, wire);
 
 	return wire;
@@ -369,7 +376,11 @@ void AigerReader::parse_xaiger()
 			continue;
 		if (m->name.begins_with("$paramod"))
 			continue;
-		auto r = box_lookup.insert(std::make_pair(it->second.as_int(), m->name));
+		auto id = it->second.as_int();
+		auto r = box_lookup.insert(std::make_pair(id, m->name));
+		if (!r.second)
+			log_error("Module '%s' has the same abc_box_id = %d value as '%s'.\n",
+					log_id(m), id, log_id(r.first->second));
 		log_assert(r.second);
 	}
 
@@ -396,13 +407,13 @@ void AigerReader::parse_xaiger()
 				for (unsigned i = 0; i < lutNum; ++i) {
 					uint32_t rootNodeID = parse_xaiger_literal(f);
 					uint32_t cutLeavesM = parse_xaiger_literal(f);
-					log_debug("rootNodeID=%d cutLeavesM=%d\n", rootNodeID, cutLeavesM);
+					log_debug2("rootNodeID=%d cutLeavesM=%d\n", rootNodeID, cutLeavesM);
 					RTLIL::Wire *output_sig = module->wire(stringf("\\__%d__", rootNodeID));
 					uint32_t nodeID;
 					RTLIL::SigSpec input_sig;
 					for (unsigned j = 0; j < cutLeavesM; ++j) {
 						nodeID = parse_xaiger_literal(f);
-						log_debug("\t%u\n", nodeID);
+						log_debug2("\t%u\n", nodeID);
 						RTLIL::Wire *wire = module->wire(stringf("\\__%d__", nodeID));
 						log_assert(wire);
 						input_sig.append(wire);
@@ -487,7 +498,7 @@ void AigerReader::parse_aiger_ascii()
 	for (unsigned i = 1; i <= I; ++i, ++line_count) {
 		if (!(f >> l1))
 			log_error("Line %u cannot be interpreted as an input!\n", line_count);
-		log_debug("%d is an input\n", l1);
+		log_debug2("%d is an input\n", l1);
 		log_assert(!(l1 & 1)); // Inputs can't be inverted
 		RTLIL::Wire *wire = createWireIfNotExists(module, l1);
 		wire->port_input = true;
@@ -499,7 +510,7 @@ void AigerReader::parse_aiger_ascii()
 	if (L > 0 && !clk_name.empty()) {
 		clk_wire = module->wire(clk_name);
 		log_assert(!clk_wire);
-		log_debug("Creating %s\n", clk_name.c_str());
+		log_debug2("Creating %s\n", clk_name.c_str());
 		clk_wire = module->addWire(clk_name);
 		clk_wire->port_input = true;
 		clk_wire->port_output = false;
@@ -507,7 +518,7 @@ void AigerReader::parse_aiger_ascii()
 	for (unsigned i = 0; i < L; ++i, ++line_count) {
 		if (!(f >> l1 >> l2))
 			log_error("Line %u cannot be interpreted as a latch!\n", line_count);
-		log_debug("%d %d is a latch\n", l1, l2);
+		log_debug2("%d %d is a latch\n", l1, l2);
 		log_assert(!(l1 & 1));
 		RTLIL::Wire *q_wire = createWireIfNotExists(module, l1);
 		RTLIL::Wire *d_wire = createWireIfNotExists(module, l2);
@@ -544,7 +555,7 @@ void AigerReader::parse_aiger_ascii()
 		if (!(f >> l1))
 			log_error("Line %u cannot be interpreted as an output!\n", line_count);
 
-		log_debug("%d is an output\n", l1);
+		log_debug2("%d is an output\n", l1);
 		const unsigned variable = l1 >> 1;
 		const bool invert = l1 & 1;
 		RTLIL::IdString wire_name(stringf("\\__%d%s__", variable, invert ? "b" : "")); // FIXME: is "b" the right suffix?
@@ -565,7 +576,7 @@ void AigerReader::parse_aiger_ascii()
 		if (!(f >> l1))
 			log_error("Line %u cannot be interpreted as a bad state property!\n", line_count);
 
-		log_debug("%d is a bad state property\n", l1);
+		log_debug2("%d is a bad state property\n", l1);
 		RTLIL::Wire *wire = createWireIfNotExists(module, l1);
 		wire->port_output = true;
 		bad_properties.push_back(wire);
@@ -588,7 +599,7 @@ void AigerReader::parse_aiger_ascii()
 		if (!(f >> l1 >> l2 >> l3))
 			log_error("Line %u cannot be interpreted as an AND!\n", line_count);
 
-		log_debug("%d %d %d is an AND\n", l1, l2, l3);
+		log_debug2("%d %d %d is an AND\n", l1, l2, l3);
 		log_assert(!(l1 & 1));
 		RTLIL::Wire *o_wire = createWireIfNotExists(module, l1);
 		RTLIL::Wire *i1_wire = createWireIfNotExists(module, l2);
@@ -614,7 +625,7 @@ void AigerReader::parse_aiger_binary()
 
 	// Parse inputs
 	for (unsigned i = 1; i <= I; ++i) {
-		log_debug("%d is an input\n", i);
+		log_debug2("%d is an input\n", i);
 		RTLIL::Wire *wire = createWireIfNotExists(module, i << 1);
 		wire->port_input = true;
 		log_assert(!wire->port_output);
@@ -626,7 +637,7 @@ void AigerReader::parse_aiger_binary()
 	if (L > 0 && !clk_name.empty()) {
 		clk_wire = module->wire(clk_name);
 		log_assert(!clk_wire);
-		log_debug("Creating %s\n", clk_name.c_str());
+		log_debug2("Creating %s\n", clk_name.c_str());
 		clk_wire = module->addWire(clk_name);
 		clk_wire->port_input = true;
 		clk_wire->port_output = false;
@@ -671,7 +682,7 @@ void AigerReader::parse_aiger_binary()
 		if (!(f >> l1))
 			log_error("Line %u cannot be interpreted as an output!\n", line_count);
 
-		log_debug("%d is an output\n", l1);
+		log_debug2("%d is an output\n", l1);
 		const unsigned variable = l1 >> 1;
 		const bool invert = l1 & 1;
 		RTLIL::IdString wire_name(stringf("\\__%d%s__", variable, invert ? "b" : "")); // FIXME: is "_b" the right suffix?
@@ -693,7 +704,7 @@ void AigerReader::parse_aiger_binary()
 		if (!(f >> l1))
 			log_error("Line %u cannot be interpreted as a bad state property!\n", line_count);
 
-		log_debug("%d is a bad state property\n", l1);
+		log_debug2("%d is a bad state property\n", l1);
 		RTLIL::Wire *wire = createWireIfNotExists(module, l1);
 		wire->port_output = true;
 		bad_properties.push_back(wire);
@@ -719,7 +730,7 @@ void AigerReader::parse_aiger_binary()
 		l2 = parse_next_delta_literal(f, l1);
 		l3 = parse_next_delta_literal(f, l2);
 
-		log_debug("%d %d %d is an AND\n", l1, l2, l3);
+		log_debug2("%d %d %d is an AND\n", l1, l2, l3);
 		log_assert(!(l1 & 1));
 		RTLIL::Wire *o_wire = createWireIfNotExists(module, l1);
 		RTLIL::Wire *i1_wire = createWireIfNotExists(module, l2);
@@ -730,7 +741,7 @@ void AigerReader::parse_aiger_binary()
 
 void AigerReader::post_process()
 {
-	pool<RTLIL::Module*> abc_carry_modules;
+	pool<IdString> seen_boxes;
 	unsigned ci_count = 0, co_count = 0, flop_count = 0;
 	for (auto cell : boxes) {
 		RTLIL::Module* box_module = design->module(cell->type);
@@ -745,38 +756,44 @@ void AigerReader::post_process()
 			log_assert(flop_module);
 			flop_past_q = box_module->attributes.at("\\abc_flop_past_q").decode_string();
 		}
-		else if (box_module->attributes.count("\\abc_carry") && !abc_carry_modules.count(box_module)) {
-			RTLIL::Wire* carry_in = nullptr, *carry_out = nullptr;
-			RTLIL::Wire* last_in = nullptr, *last_out = nullptr;
-			for (const auto &port_name : box_module->ports) {
-				RTLIL::Wire* w = box_module->wire(port_name);
-				log_assert(w);
-				if (w->port_input) {
-					if (w->attributes.count("\\abc_carry_in")) {
-						log_assert(!carry_in);
-						carry_in = w;
-					}
-					log_assert(!last_in || last_in->port_id < w->port_id);
-					last_in = w;
-				}
-				if (w->port_output) {
-					if (w->attributes.count("\\abc_carry_out")) {
-						log_assert(!carry_out);
-						carry_out = w;
+        else if (seen_boxes.insert(cell->type).second) {
+			auto it = box_module->attributes.find("\\abc_carry");
+			if (it != box_module->attributes.end()) {
+				RTLIL::Wire *carry_in = nullptr, *carry_out = nullptr;
+				auto carry_in_out = it->second.decode_string();
+				auto pos = carry_in_out.find(',');
+				if (pos == std::string::npos)
+					log_error("'abc_carry' attribute on module '%s' does not contain ','.\n", log_id(cell->type));
+				auto carry_in_name = RTLIL::escape_id(carry_in_out.substr(0, pos));
+				carry_in = box_module->wire(carry_in_name);
+				if (!carry_in || !carry_in->port_input)
+					log_error("'abc_carry' on module '%s' contains '%s' which does not exist or is not an input port.\n", log_id(cell->type), carry_in_name.c_str());
+
+				auto carry_out_name = RTLIL::escape_id(carry_in_out.substr(pos+1));
+				carry_out = box_module->wire(carry_out_name);
+				if (!carry_out || !carry_out->port_output)
+					log_error("'abc_carry' on module '%s' contains '%s' which does not exist or is not an output port.\n", log_id(cell->type), carry_out_name.c_str());
+
+				auto &ports = box_module->ports;
+				for (auto jt = ports.begin(); jt != ports.end(); ) {
+					RTLIL::Wire* w = box_module->wire(*jt);
+					log_assert(w);
+					if (w == carry_in || w == carry_out) {
+						jt = ports.erase(jt);
+						continue;
 					}
-					log_assert(!last_out || last_out->port_id < w->port_id);
-					last_out = w;
+					if (w->port_id > carry_in->port_id)
+						--w->port_id;
+					if (w->port_id > carry_out->port_id)
+						--w->port_id;
+					log_assert(w->port_input || w->port_output);
+					log_assert(ports[w->port_id-1] == w->name);
+					++jt;
 				}
-			}
-
-			if (carry_in != last_in) {
-				std::swap(box_module->ports[carry_in->port_id], box_module->ports[last_in->port_id]);
-				std::swap(carry_in->port_id, last_in->port_id);
-			}
-			if (carry_out != last_out) {
-				log_assert(last_out);
-				std::swap(box_module->ports[carry_out->port_id], box_module->ports[last_out->port_id]);
-				std::swap(carry_out->port_id, last_out->port_id);
+				ports.push_back(carry_in->name);
+				carry_in->port_id = ports.size();
+				ports.push_back(carry_out->name);
+				carry_out->port_id = ports.size();
 			}
 		}
 
@@ -873,7 +890,10 @@ void AigerReader::post_process()
 				RTLIL::Wire* wire = outputs[variable + co_count];
 				log_assert(wire);
 				log_assert(wire->port_output);
-				log_debug("Renaming output %s", log_id(wire));
+				if (escaped_s == "$__dummy__") {
+					wire->port_output = false;
+					continue;
+				}
 
 				if (index == 0) {
 					// Cope with the fact that a CO might be identical
@@ -988,10 +1008,15 @@ void AigerReader::post_process()
 			if (other_wire) {
 				other_wire->port_input = false;
 				other_wire->port_output = false;
-				if (wire->port_input)
+			}
+			if (wire->port_input) {
+				if (other_wire)
 					module->connect(other_wire, SigSpec(wire, i));
-				else
-					module->connect(SigSpec(wire, i), other_wire);
+			}
+			else {
+								  // Since we skip POs that are connected to Sx,
+								  // re-connect them here
+				module->connect(SigSpec(wire, i), other_wire ? other_wire : SigSpec(RTLIL::Sx));
 			}
 		}
 	}
diff --git a/frontends/ast/ast.cc b/frontends/ast/ast.cc
index b5b968e9e..3d066af53 100644
--- a/frontends/ast/ast.cc
+++ b/frontends/ast/ast.cc
@@ -46,7 +46,7 @@ namespace AST {
 // instantiate global variables (private API)
 namespace AST_INTERNAL {
 	bool flag_dump_ast1, flag_dump_ast2, flag_no_dump_ptr, flag_dump_vlog1, flag_dump_vlog2, flag_dump_rtlil, flag_nolatches, flag_nomeminit;
-	bool flag_nomem2reg, flag_mem2reg, flag_noblackbox, flag_lib, flag_nowb, flag_noopt, flag_icells, flag_autowire;
+	bool flag_nomem2reg, flag_mem2reg, flag_noblackbox, flag_lib, flag_nowb, flag_noopt, flag_icells, flag_pwires, flag_autowire;
 	AstNode *current_ast, *current_ast_mod;
 	std::map<std::string, AstNode*> current_scope;
 	const dict<RTLIL::SigBit, RTLIL::SigBit> *genRTLIL_subst_ptr = NULL;
@@ -1112,6 +1112,7 @@ static AstModule* process_module(AstNode *ast, bool defer, AstNode *original_ast
 	current_module->nowb = flag_nowb;
 	current_module->noopt = flag_noopt;
 	current_module->icells = flag_icells;
+	current_module->pwires = flag_pwires;
 	current_module->autowire = flag_autowire;
 	current_module->fixup_ports();
 
@@ -1126,7 +1127,7 @@ static AstModule* process_module(AstNode *ast, bool defer, AstNode *original_ast
 
 // create AstModule instances for all modules in the AST tree and add them to 'design'
 void AST::process(RTLIL::Design *design, AstNode *ast, bool dump_ast1, bool dump_ast2, bool no_dump_ptr, bool dump_vlog1, bool dump_vlog2, bool dump_rtlil,
-		bool nolatches, bool nomeminit, bool nomem2reg, bool mem2reg, bool noblackbox, bool lib, bool nowb, bool noopt, bool icells, bool nooverwrite, bool overwrite, bool defer, bool autowire)
+		bool nolatches, bool nomeminit, bool nomem2reg, bool mem2reg, bool noblackbox, bool lib, bool nowb, bool noopt, bool icells, bool pwires, bool nooverwrite, bool overwrite, bool defer, bool autowire)
 {
 	current_ast = ast;
 	flag_dump_ast1 = dump_ast1;
@@ -1144,6 +1145,7 @@ void AST::process(RTLIL::Design *design, AstNode *ast, bool dump_ast1, bool dump
 	flag_nowb = nowb;
 	flag_noopt = noopt;
 	flag_icells = icells;
+	flag_pwires = pwires;
 	flag_autowire = autowire;
 
 	log_assert(current_ast->type == AST_DESIGN);
@@ -1480,6 +1482,7 @@ std::string AstModule::derive_common(RTLIL::Design *design, dict<RTLIL::IdString
 	flag_nowb = nowb;
 	flag_noopt = noopt;
 	flag_icells = icells;
+	flag_pwires = pwires;
 	flag_autowire = autowire;
 	use_internal_line_num();
 
@@ -1551,6 +1554,7 @@ RTLIL::Module *AstModule::clone() const
 	new_mod->lib = lib;
 	new_mod->noopt = noopt;
 	new_mod->icells = icells;
+	new_mod->pwires = pwires;
 	new_mod->autowire = autowire;
 
 	return new_mod;
diff --git a/frontends/ast/ast.h b/frontends/ast/ast.h
index b8cde060e..54b2fb319 100644
--- a/frontends/ast/ast.h
+++ b/frontends/ast/ast.h
@@ -286,13 +286,13 @@ namespace AST
 
 	// process an AST tree (ast must point to an AST_DESIGN node) and generate RTLIL code
 	void process(RTLIL::Design *design, AstNode *ast, bool dump_ast1, bool dump_ast2, bool no_dump_ptr, bool dump_vlog1, bool dump_vlog2, bool dump_rtlil, bool nolatches, bool nomeminit,
-			bool nomem2reg, bool mem2reg, bool noblackbox, bool lib, bool nowb, bool noopt, bool icells, bool nooverwrite, bool overwrite, bool defer, bool autowire);
+			bool nomem2reg, bool mem2reg, bool noblackbox, bool lib, bool nowb, bool noopt, bool icells, bool pwires, bool nooverwrite, bool overwrite, bool defer, bool autowire);
 
 	// parametric modules are supported directly by the AST library
 	// therefore we need our own derivate of RTLIL::Module with overloaded virtual functions
 	struct AstModule : RTLIL::Module {
 		AstNode *ast;
-		bool nolatches, nomeminit, nomem2reg, mem2reg, noblackbox, lib, nowb, noopt, icells, autowire;
+		bool nolatches, nomeminit, nomem2reg, mem2reg, noblackbox, lib, nowb, noopt, icells, pwires, autowire;
 		~AstModule() YS_OVERRIDE;
 		RTLIL::IdString derive(RTLIL::Design *design, dict<RTLIL::IdString, RTLIL::Const> parameters, bool mayfail) YS_OVERRIDE;
 		RTLIL::IdString derive(RTLIL::Design *design, dict<RTLIL::IdString, RTLIL::Const> parameters, dict<RTLIL::IdString, RTLIL::Module*> interfaces, dict<RTLIL::IdString, RTLIL::IdString> modports, bool mayfail) YS_OVERRIDE;
@@ -325,7 +325,7 @@ namespace AST_INTERNAL
 {
 	// internal state variables
 	extern bool flag_dump_ast1, flag_dump_ast2, flag_no_dump_ptr, flag_dump_rtlil, flag_nolatches, flag_nomeminit;
-	extern bool flag_nomem2reg, flag_mem2reg, flag_lib, flag_noopt, flag_icells, flag_autowire;
+	extern bool flag_nomem2reg, flag_mem2reg, flag_lib, flag_noopt, flag_icells, flag_pwires, flag_autowire;
 	extern AST::AstNode *current_ast, *current_ast_mod;
 	extern std::map<std::string, AST::AstNode*> current_scope;
 	extern const dict<RTLIL::SigBit, RTLIL::SigBit> *genRTLIL_subst_ptr;
diff --git a/frontends/ast/genrtlil.cc b/frontends/ast/genrtlil.cc
index 32ed401eb..079fc11e5 100644
--- a/frontends/ast/genrtlil.cc
+++ b/frontends/ast/genrtlil.cc
@@ -853,7 +853,6 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
 	case AST_FUNCTION:
 	case AST_DPI_FUNCTION:
 	case AST_AUTOWIRE:
-	case AST_LOCALPARAM:
 	case AST_DEFPARAM:
 	case AST_GENVAR:
 	case AST_GENFOR:
@@ -895,6 +894,26 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
 	// remember the parameter, needed for example in techmap
 	case AST_PARAMETER:
 		current_module->avail_parameters.insert(str);
+		/* fall through */
+	case AST_LOCALPARAM:
+		if (flag_pwires)
+		{
+			if (GetSize(children) < 1 || children[0]->type != AST_CONSTANT)
+				log_file_error(filename, linenum, "Parameter `%s' with non-constant value!\n", str.c_str());
+
+			RTLIL::Const val = children[0]->bitsAsConst();
+			RTLIL::Wire *wire = current_module->addWire(str, GetSize(val));
+			current_module->connect(wire, val);
+
+			wire->attributes["\\src"] = stringf("%s:%d", filename.c_str(), linenum);
+			wire->attributes[type == AST_PARAMETER ? "\\parameter" : "\\localparam"] = 1;
+
+			for (auto &attr : attributes) {
+				if (attr.second->type != AST_CONSTANT)
+					log_file_error(filename, linenum, "Attribute `%s' with non-constant value!\n", attr.first.c_str());
+				wire->attributes[attr.first] = attr.second->asAttrConst();
+			}
+		}
 		break;
 
 	// create an RTLIL::Wire for an AST_WIRE node
diff --git a/frontends/json/jsonparse.cc b/frontends/json/jsonparse.cc
index 82361ea9b..f5ae8eb72 100644
--- a/frontends/json/jsonparse.cc
+++ b/frontends/json/jsonparse.cc
@@ -292,6 +292,18 @@ void json_import(Design *design, string &modname, JsonNode *node)
 			if (port_wire == nullptr)
 				port_wire = module->addWire(port_name, GetSize(port_bits_node->data_array));
 
+			if (port_node->data_dict.count("upto") != 0) {
+				JsonNode *val = port_node->data_dict.at("upto");
+				if (val->type == 'N')
+					port_wire->upto = val->data_number != 0;
+			}
+
+			if (port_node->data_dict.count("offset") != 0) {
+				JsonNode *val = port_node->data_dict.at("offset");
+				if (val->type == 'N')
+					port_wire->start_offset = val->data_number;
+			}
+
 			if (port_direction_node->data_string == "input") {
 				port_wire->port_input = true;
 			} else
@@ -372,6 +384,18 @@ void json_import(Design *design, string &modname, JsonNode *node)
 			if (wire == nullptr)
 				wire = module->addWire(net_name, GetSize(bits_node->data_array));
 
+			if (net_node->data_dict.count("upto") != 0) {
+				JsonNode *val = net_node->data_dict.at("upto");
+				if (val->type == 'N')
+					wire->upto = val->data_number != 0;
+			}
+
+			if (net_node->data_dict.count("offset") != 0) {
+				JsonNode *val = net_node->data_dict.at("offset");
+				if (val->type == 'N')
+					wire->start_offset = val->data_number;
+			}
+
 			for (int i = 0; i < GetSize(bits_node->data_array); i++)
 			{
 				JsonNode *bitval_node = bits_node->data_array.at(i);
diff --git a/frontends/verilog/const2ast.cc b/frontends/verilog/const2ast.cc
index 57d366dbf..f6a17b242 100644
--- a/frontends/verilog/const2ast.cc
+++ b/frontends/verilog/const2ast.cc
@@ -153,7 +153,7 @@ AstNode *VERILOG_FRONTEND::const2ast(std::string code, char case_type, bool warn
 {
 	if (warn_z) {
 		AstNode *ret = const2ast(code, case_type);
-		if (std::find(ret->bits.begin(), ret->bits.end(), RTLIL::State::Sz) != ret->bits.end())
+		if (ret != nullptr && std::find(ret->bits.begin(), ret->bits.end(), RTLIL::State::Sz) != ret->bits.end())
 			log_warning("Yosys has only limited support for tri-state logic at the moment. (%s:%d)\n",
 				current_filename.c_str(), get_line_num());
 		return ret;
@@ -204,7 +204,7 @@ AstNode *VERILOG_FRONTEND::const2ast(std::string code, char case_type, bool warn
 	{
 		std::vector<RTLIL::State> data;
 		bool is_signed = false;
-		bool is_unsized = false;
+		bool is_unsized = len_in_bits < 0;
 		if (*(endptr+1) == 's') {
 			is_signed = true;
 			endptr++;
@@ -213,25 +213,25 @@ AstNode *VERILOG_FRONTEND::const2ast(std::string code, char case_type, bool warn
 		{
 		case 'b':
 		case 'B':
-			my_strtobin(data, endptr+2, len_in_bits, 2, case_type, false);
+			my_strtobin(data, endptr+2, len_in_bits, 2, case_type, is_unsized);
 			break;
 		case 'o':
 		case 'O':
-			my_strtobin(data, endptr+2, len_in_bits, 8, case_type, false);
+			my_strtobin(data, endptr+2, len_in_bits, 8, case_type, is_unsized);
 			break;
 		case 'd':
 		case 'D':
-			my_strtobin(data, endptr+2, len_in_bits, 10, case_type, false);
+			my_strtobin(data, endptr+2, len_in_bits, 10, case_type, is_unsized);
 			break;
 		case 'h':
 		case 'H':
-			my_strtobin(data, endptr+2, len_in_bits, 16, case_type, false);
+			my_strtobin(data, endptr+2, len_in_bits, 16, case_type, is_unsized);
 			break;
 		default:
 			char next_char = char(tolower(*(endptr+1)));
 			if (next_char == '0' || next_char == '1' || next_char == 'x' || next_char == 'z') {
-				my_strtobin(data, endptr+1, 1, 2, case_type, true);
 				is_unsized = true;
+				my_strtobin(data, endptr+1, 1, 2, case_type, is_unsized);
 			} else {
 				return NULL;
 			}
diff --git a/frontends/verilog/verilog_frontend.cc b/frontends/verilog/verilog_frontend.cc
index 01e589efb..0e2bead6f 100644
--- a/frontends/verilog/verilog_frontend.cc
+++ b/frontends/verilog/verilog_frontend.cc
@@ -168,6 +168,9 @@ struct VerilogFrontend : public Frontend {
 		log("    -icells\n");
 		log("        interpret cell types starting with '$' as internal cell types\n");
 		log("\n");
+		log("    -pwires\n");
+		log("        add a wire for each module parameter\n");
+		log("\n");
 		log("    -nooverwrite\n");
 		log("        ignore re-definitions of modules. (the default behavior is to\n");
 		log("        create an error message if the existing module is not a black box\n");
@@ -228,6 +231,7 @@ struct VerilogFrontend : public Frontend {
 		bool flag_nodpi = false;
 		bool flag_noopt = false;
 		bool flag_icells = false;
+		bool flag_pwires = false;
 		bool flag_nooverwrite = false;
 		bool flag_overwrite = false;
 		bool flag_defer = false;
@@ -368,6 +372,10 @@ struct VerilogFrontend : public Frontend {
 				flag_icells = true;
 				continue;
 			}
+			if (arg == "-pwires") {
+				flag_pwires = true;
+				continue;
+			}
 			if (arg == "-ignore_redef" || arg == "-nooverwrite") {
 				flag_nooverwrite = true;
 				flag_overwrite = false;
@@ -458,7 +466,7 @@ struct VerilogFrontend : public Frontend {
 			error_on_dpi_function(current_ast);
 
 		AST::process(design, current_ast, flag_dump_ast1, flag_dump_ast2, flag_no_dump_ptr, flag_dump_vlog1, flag_dump_vlog2, flag_dump_rtlil, flag_nolatches,
-				flag_nomeminit, flag_nomem2reg, flag_mem2reg, flag_noblackbox, lib_mode, flag_nowb, flag_noopt, flag_icells, flag_nooverwrite, flag_overwrite, flag_defer, default_nettype_wire);
+				flag_nomeminit, flag_nomem2reg, flag_mem2reg, flag_noblackbox, lib_mode, flag_nowb, flag_noopt, flag_icells, flag_pwires, flag_nooverwrite, flag_overwrite, flag_defer, default_nettype_wire);
 
 		if (!flag_nopp)
 			delete lexin;
diff --git a/frontends/verilog/verilog_lexer.l b/frontends/verilog/verilog_lexer.l
index 3c612472d..d3fd91473 100644
--- a/frontends/verilog/verilog_lexer.l
+++ b/frontends/verilog/verilog_lexer.l
@@ -313,7 +313,7 @@ supply1 { return TOK_SUPPLY1; }
 
 "$"(info|warning|error|fatal) {
 	frontend_verilog_yylval.string = new std::string(yytext);
-	return TOK_ELAB_TASK;
+	return TOK_MSG_TASKS;
 }
 
 "$signed"   { return TOK_TO_SIGNED; }
diff --git a/frontends/verilog/verilog_parser.y b/frontends/verilog/verilog_parser.y
index a034f9601..d89b2dc88 100644
--- a/frontends/verilog/verilog_parser.y
+++ b/frontends/verilog/verilog_parser.y
@@ -133,7 +133,7 @@ struct specify_rise_fall {
 }
 
 %token <string> TOK_STRING TOK_ID TOK_CONSTVAL TOK_REALVAL TOK_PRIMITIVE
-%token <string> TOK_SVA_LABEL TOK_SPECIFY_OPER TOK_ELAB_TASK
+%token <string> TOK_SVA_LABEL TOK_SPECIFY_OPER TOK_MSG_TASKS
 %token TOK_ASSERT TOK_ASSUME TOK_RESTRICT TOK_COVER TOK_FINAL
 %token ATTR_BEGIN ATTR_END DEFATTR_BEGIN DEFATTR_END
 %token TOK_MODULE TOK_ENDMODULE TOK_PARAMETER TOK_LOCALPARAM TOK_DEFPARAM
@@ -319,15 +319,17 @@ module_para_list:
 
 single_module_para:
 	/* empty */ |
-	TOK_PARAMETER {
+	attr TOK_PARAMETER {
 		if (astbuf1) delete astbuf1;
 		astbuf1 = new AstNode(AST_PARAMETER);
 		astbuf1->children.push_back(AstNode::mkconst_int(0, true));
+		append_attr(astbuf1, $1);
 	} param_signed param_integer param_range single_param_decl |
-	TOK_LOCALPARAM {
+	attr TOK_LOCALPARAM {
 		if (astbuf1) delete astbuf1;
 		astbuf1 = new AstNode(AST_LOCALPARAM);
 		astbuf1->children.push_back(AstNode::mkconst_int(0, true));
+		append_attr(astbuf1, $1);
 	} param_signed param_integer param_range single_param_decl |
 	single_param_decl;
 
@@ -345,7 +347,13 @@ module_arg_opt_assignment:
 		if (ast_stack.back()->children.size() > 0 && ast_stack.back()->children.back()->type == AST_WIRE) {
 			AstNode *wire = new AstNode(AST_IDENTIFIER);
 			wire->str = ast_stack.back()->children.back()->str;
-			if (ast_stack.back()->children.back()->is_reg)
+			if (ast_stack.back()->children.back()->is_input) {
+				AstNode *n = ast_stack.back()->children.back();
+				if (n->attributes.count("\\defaultvalue"))
+					delete n->attributes.at("\\defaultvalue");
+				n->attributes["\\defaultvalue"] = $2;
+			} else
+			if (ast_stack.back()->children.back()->is_reg || ast_stack.back()->children.back()->is_logic)
 				ast_stack.back()->children.push_back(new AstNode(AST_INITIAL, new AstNode(AST_BLOCK, new AstNode(AST_ASSIGN_LE, wire, $2))));
 			else
 				ast_stack.back()->children.push_back(new AstNode(AST_ASSIGN, wire, $2));
@@ -509,6 +517,7 @@ wire_type_token:
 	TOK_GENVAR {
 		astbuf3->type = AST_GENVAR;
 		astbuf3->is_reg = true;
+		astbuf3->is_signed = true;
 		astbuf3->range_left = 31;
 		astbuf3->range_right = 0;
 	} |
@@ -1211,6 +1220,7 @@ param_decl:
 	attr TOK_PARAMETER {
 		astbuf1 = new AstNode(AST_PARAMETER);
 		astbuf1->children.push_back(AstNode::mkconst_int(0, true));
+		append_attr(astbuf1, $1);
 	} param_signed param_integer param_real param_range param_decl_list ';' {
 		delete astbuf1;
 	};
@@ -1219,6 +1229,7 @@ localparam_decl:
 	attr TOK_LOCALPARAM {
 		astbuf1 = new AstNode(AST_LOCALPARAM);
 		astbuf1->children.push_back(AstNode::mkconst_int(0, true));
+		append_attr(astbuf1, $1);
 	} param_signed param_integer param_real param_range param_decl_list ';' {
 		delete astbuf1;
 	};
@@ -1360,7 +1371,12 @@ wire_name_and_opt_assign:
 	wire_name '=' expr {
 		AstNode *wire = new AstNode(AST_IDENTIFIER);
 		wire->str = ast_stack.back()->children.back()->str;
-		if (astbuf1->is_reg)
+		if (astbuf1->is_input) {
+			if (astbuf1->attributes.count("\\defaultvalue"))
+				delete astbuf1->attributes.at("\\defaultvalue");
+			astbuf1->attributes["\\defaultvalue"] = $3;
+		} else
+		if (astbuf1->is_reg || astbuf1->is_logic)
 			ast_stack.back()->children.push_back(new AstNode(AST_INITIAL, new AstNode(AST_BLOCK, new AstNode(AST_ASSIGN_LE, wire, $3))));
 		else
 			ast_stack.back()->children.push_back(new AstNode(AST_ASSIGN, wire, $3));
@@ -1385,7 +1401,13 @@ wire_name:
 				node->children.push_back(rng);
 			}
 			node->type = AST_MEMORY;
-			node->children.push_back($2);
+			auto *rangeNode = $2;
+			if (rangeNode->type == AST_RANGE && rangeNode->children.size() == 1) {
+				// SV array size [n], rewrite as [n-1:0]
+				rangeNode->children[0] = new AstNode(AST_SUB, rangeNode->children[0], AstNode::mkconst_int(1, true));
+				rangeNode->children.push_back(AstNode::mkconst_int(0, false));
+			}
+			node->children.push_back(rangeNode);
 		}
 		if (current_function_or_task == NULL) {
 			if (do_not_require_port_stubs && (node->is_input || node->is_output) && port_stubs.count(*$1) == 0) {
@@ -1881,6 +1903,16 @@ behavioral_stmt:
 	} opt_arg_list ';'{
 		ast_stack.pop_back();
 	} |
+	TOK_MSG_TASKS attr {
+		AstNode *node = new AstNode(AST_TCALL);
+		node->str = *$1;
+		delete $1;
+		ast_stack.back()->children.push_back(node);
+		ast_stack.push_back(node);
+		append_attr(node, $2);
+	} opt_arg_list ';'{
+		ast_stack.pop_back();
+	} |
 	attr TOK_BEGIN opt_label {
 		AstNode *node = new AstNode(AST_BLOCK);
 		ast_stack.back()->children.push_back(node);
@@ -2177,7 +2209,7 @@ gen_stmt:
 			delete $6;
 		ast_stack.pop_back();
 	} |
-	TOK_ELAB_TASK {
+	TOK_MSG_TASKS {
 		AstNode *node = new AstNode(AST_TECALL);
 		node->str = *$1;
 		delete $1;
diff --git a/kernel/celltypes.h b/kernel/celltypes.h
index 4e91eddda..758661c02 100644
--- a/kernel/celltypes.h
+++ b/kernel/celltypes.h
@@ -246,24 +246,24 @@ struct CellTypes
 		cell_types.clear();
 	}
 
-	bool cell_known(RTLIL::IdString type)
+	bool cell_known(RTLIL::IdString type) const
 	{
 		return cell_types.count(type) != 0;
 	}
 
-	bool cell_output(RTLIL::IdString type, RTLIL::IdString port)
+	bool cell_output(RTLIL::IdString type, RTLIL::IdString port) const
 	{
 		auto it = cell_types.find(type);
 		return it != cell_types.end() && it->second.outputs.count(port) != 0;
 	}
 
-	bool cell_input(RTLIL::IdString type, RTLIL::IdString port)
+	bool cell_input(RTLIL::IdString type, RTLIL::IdString port) const
 	{
 		auto it = cell_types.find(type);
 		return it != cell_types.end() && it->second.inputs.count(port) != 0;
 	}
 
-	bool cell_evaluable(RTLIL::IdString type)
+	bool cell_evaluable(RTLIL::IdString type) const
 	{
 		auto it = cell_types.find(type);
 		return it != cell_types.end() && it->second.is_evaluable;
@@ -482,4 +482,3 @@ extern CellTypes yosys_celltypes;
 YOSYS_NAMESPACE_END
 
 #endif
-
diff --git a/kernel/register.cc b/kernel/register.cc
index 71eb6b187..26da96b95 100644
--- a/kernel/register.cc
+++ b/kernel/register.cc
@@ -545,6 +545,7 @@ void Backend::extra_args(std::ostream *&f, std::string &filename, std::vector<st
 		}
 
 		filename = arg;
+		rewrite_filename(filename);
 		std::ofstream *ff = new std::ofstream;
 		ff->open(filename.c_str(), std::ofstream::trunc);
 		yosys_output_files.insert(filename);
diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index f732b56b0..a09f4a0d1 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -1381,7 +1381,34 @@ void RTLIL::Module::check()
 	for (auto &it : processes) {
 		log_assert(it.first == it.second->name);
 		log_assert(!it.first.empty());
-		// FIXME: More checks here..
+		log_assert(it.second->root_case.compare.empty());
+		std::vector<CaseRule*> all_cases = {&it.second->root_case};
+		for (size_t i = 0; i < all_cases.size(); i++) {
+			for (auto &switch_it : all_cases[i]->switches) {
+				for (auto &case_it : switch_it->cases) {
+					for (auto &compare_it : case_it->compare) {
+						log_assert(switch_it->signal.size() == compare_it.size());
+					}
+					all_cases.push_back(case_it);
+				}
+			}
+		}
+		for (auto &sync_it : it.second->syncs) {
+			switch (sync_it->type) {
+				case SyncType::ST0:
+				case SyncType::ST1:
+				case SyncType::STp:
+				case SyncType::STn:
+				case SyncType::STe:
+					log_assert(!sync_it->signal.empty());
+					break;
+				case SyncType::STa:
+				case SyncType::STg:
+				case SyncType::STi:
+					log_assert(sync_it->signal.empty());
+					break;
+			}
+		}
 	}
 
 	for (auto &it : connections_) {
@@ -1565,21 +1592,13 @@ void RTLIL::Module::remove(const pool<RTLIL::Wire*> &wires)
 
 void RTLIL::Module::remove(RTLIL::Cell *cell)
 {
-	auto it = cells_.find(cell->name);
-	log_assert(it != cells_.end());
-	remove(it);
-}
-
-dict<RTLIL::IdString, RTLIL::Cell*>::iterator RTLIL::Module::remove(dict<RTLIL::IdString, RTLIL::Cell*>::iterator it)
-{
-	RTLIL::Cell *cell = it->second;
 	while (!cell->connections_.empty())
 		cell->unsetPort(cell->connections_.begin()->first);
 
+	log_assert(cells_.count(cell->name) != 0);
 	log_assert(refcount_cells_ == 0);
-	it = cells_.erase(it);
+	cells_.erase(cell->name);
 	delete cell;
-	return it;
 }
 
 void RTLIL::Module::rename(RTLIL::Wire *wire, RTLIL::IdString new_name)
diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index 4a0f8b4f8..f4fcf5dcf 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -1040,7 +1040,6 @@ public:
 	// Removing wires is expensive. If you have to remove wires, remove them all at once.
 	void remove(const pool<RTLIL::Wire*> &wires);
 	void remove(RTLIL::Cell *cell);
-	dict<RTLIL::IdString, RTLIL::Cell*>::iterator remove(dict<RTLIL::IdString, RTLIL::Cell*>::iterator it);
 
 	void rename(RTLIL::Wire *wire, RTLIL::IdString new_name);
 	void rename(RTLIL::Cell *cell, RTLIL::IdString new_name);
diff --git a/kernel/yosys.cc b/kernel/yosys.cc
index 377572fc2..94d6d675f 100644
--- a/kernel/yosys.cc
+++ b/kernel/yosys.cc
@@ -651,6 +651,10 @@ void rewrite_filename(std::string &filename)
 		filename = filename.substr(1, GetSize(filename)-2);
 	if (filename.substr(0, 2) == "+/")
 		filename = proc_share_dirname() + filename.substr(2);
+#ifndef _WIN32
+	if (filename.substr(0, 2) == "~/")
+		filename = filename.replace(0, 1, getenv("HOME"));
+#endif
 }
 
 #ifdef YOSYS_ENABLE_TCL
diff --git a/manual/CHAPTER_Overview.tex b/manual/CHAPTER_Overview.tex
index 2feb0f1cb..1a25c477f 100644
--- a/manual/CHAPTER_Overview.tex
+++ b/manual/CHAPTER_Overview.tex
@@ -350,6 +350,18 @@ and this bit is a one (the second ``1'').} for {\tt \textbackslash{}reset == 1}
 sets {\tt \$0\textbackslash{}q[0:0]} to the value of {\tt \textbackslash{}d} if {\tt
 \textbackslash{}enable} is active (lines $6 \dots 11$).
 
+A case can specify zero or more compare values that will determine whether it matches. Each of the compare values
+must be the exact same width as the control signal. When more than one compare value is specified, the case matches
+if any of them matches the control signal; when zero compare values are specified, the case always matches (i.e.
+it is the default case).
+
+A switch prioritizes cases from first to last: multiple cases can match, but only the first matched case becomes
+active. This normally synthesizes to a priority encoder. The {\tt parallel\_case} attribute allows passes to assume
+that no more than one case will match, and {\tt full\_case} attribute allows passes to assume that exactly one
+case will match; if these invariants are ever dynamically violated, the behavior is undefined. These attributes
+are useful when an invariant invisible to the synthesizer causes the control signal to never take certain
+bit patterns.
+
 The lines $13 \dots 16$  then cause {\tt \textbackslash{}q} to be updated whenever there is
 a positive clock edge on {\tt \textbackslash{}clock} or {\tt \textbackslash{}reset}.
 
diff --git a/passes/cmds/blackbox.cc b/passes/cmds/blackbox.cc
index 6094f8f16..d09ed872e 100644
--- a/passes/cmds/blackbox.cc
+++ b/passes/cmds/blackbox.cc
@@ -23,7 +23,7 @@ USING_YOSYS_NAMESPACE
 PRIVATE_NAMESPACE_BEGIN
 
 struct BlackboxPass : public Pass {
-	BlackboxPass() : Pass("blackbox", "change type of cells in the design") { }
+	BlackboxPass() : Pass("blackbox", "convert modules into blackbox modules") { }
 	void help() YS_OVERRIDE
 	{
 		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
diff --git a/passes/cmds/stat.cc b/passes/cmds/stat.cc
index d22685b62..27c5fb60c 100644
--- a/passes/cmds/stat.cc
+++ b/passes/cmds/stat.cc
@@ -285,8 +285,8 @@ struct StatPass : public Pass {
 		log("        use cell area information from the provided liberty file\n");
 		log("\n");
 		log("    -tech <technology>\n");
-		log("        print area estemate for the specified technology. Corrently supported\n");
-		log("        calues for <technology>: xilinx\n");
+		log("        print area estemate for the specified technology. Currently supported\n");
+		log("        values for <technology>: xilinx\n");
 		log("\n");
 		log("    -width\n");
 		log("        annotate internal cell types with their word width.\n");
diff --git a/passes/cmds/write_file.cc b/passes/cmds/write_file.cc
index 9613b462b..64a762d7c 100644
--- a/passes/cmds/write_file.cc
+++ b/passes/cmds/write_file.cc
@@ -62,7 +62,7 @@ struct WriteFileFrontend : public Frontend {
 		if (argidx < args.size() && args[argidx].rfind("-", 0) != 0)
 			output_filename = args[argidx++];
 		else
-			log_cmd_error("Missing putput filename.\n");
+			log_cmd_error("Missing output filename.\n");
 
 		extra_args(f, filename, args, argidx);
 
diff --git a/passes/hierarchy/hierarchy.cc b/passes/hierarchy/hierarchy.cc
index 24e64a9b2..213437c01 100644
--- a/passes/hierarchy/hierarchy.cc
+++ b/passes/hierarchy/hierarchy.cc
@@ -591,6 +591,9 @@ struct HierarchyPass : public Pass {
 		log("        module instances when the width does not match the module port. This\n");
 		log("        option disables this behavior.\n");
 		log("\n");
+		log("    -nodefaults\n");
+		log("        do not resolve input port default values\n");
+		log("\n");
 		log("    -nokeep_asserts\n");
 		log("        per default this pass sets the \"keep\" attribute on all modules\n");
 		log("        that directly or indirectly contain one or more formal properties.\n");
@@ -645,6 +648,7 @@ struct HierarchyPass : public Pass {
 		bool generate_mode = false;
 		bool keep_positionals = false;
 		bool keep_portwidths = false;
+		bool nodefaults = false;
 		bool nokeep_asserts = false;
 		std::vector<std::string> generate_cells;
 		std::vector<generate_port_decl_t> generate_ports;
@@ -712,6 +716,10 @@ struct HierarchyPass : public Pass {
 				keep_portwidths = true;
 				continue;
 			}
+			if (args[argidx] == "-nodefaults") {
+				nodefaults = true;
+				continue;
+			}
 			if (args[argidx] == "-nokeep_asserts") {
 				nokeep_asserts = true;
 				continue;
@@ -940,6 +948,36 @@ struct HierarchyPass : public Pass {
 			}
 		}
 
+		if (!nodefaults)
+		{
+			dict<IdString, dict<IdString, Const>> defaults_db;
+
+			for (auto module : design->modules())
+				for (auto wire : module->wires())
+					if (wire->port_input && wire->attributes.count("\\defaultvalue"))
+						defaults_db[module->name][wire->name] = wire->attributes.at("\\defaultvalue");
+
+			for (auto module : design->modules())
+				for (auto cell : module->cells())
+				{
+					if (defaults_db.count(cell->type) == 0)
+						continue;
+
+					if (keep_positionals) {
+						bool found_positionals = false;
+						for (auto &conn : cell->connections())
+							if (conn.first[0] == '$' && '0' <= conn.first[1] && conn.first[1] <= '9')
+								found_positionals = true;
+						if (found_positionals)
+							continue;
+					}
+
+					for (auto &it : defaults_db.at(cell->type))
+						if (!cell->hasPort(it.first))
+							cell->setPort(it.first, it.second);
+				}
+		}
+
 		std::set<Module*> blackbox_derivatives;
 		std::vector<Module*> design_modules = design->modules();
 
diff --git a/passes/memory/memory_dff.cc b/passes/memory/memory_dff.cc
index 220d29295..5215cce44 100644
--- a/passes/memory/memory_dff.cc
+++ b/passes/memory/memory_dff.cc
@@ -182,11 +182,17 @@ struct MemoryDffWorker
 
 		if (mux_cells_a.count(sig_data) || mux_cells_b.count(sig_data))
 		{
-			bool enable_invert = mux_cells_a.count(sig_data) != 0;
-			Cell *mux = enable_invert ? mux_cells_a.at(sig_data) : mux_cells_b.at(sig_data);
-			SigSpec check_q = sigmap(mux->getPort(enable_invert ? "\\B" : "\\A"));
+			RTLIL::SigSpec en;
+			RTLIL::SigSpec check_q;
+
+			do {
+				bool enable_invert = mux_cells_a.count(sig_data) != 0;
+				Cell *mux = enable_invert ? mux_cells_a.at(sig_data) : mux_cells_b.at(sig_data);
+				check_q = sigmap(mux->getPort(enable_invert ? "\\B" : "\\A"));
+				sig_data = sigmap(mux->getPort("\\Y"));
+				en.append(enable_invert ? module->LogicNot(NEW_ID, mux->getPort("\\S")) : mux->getPort("\\S"));
+			} while (mux_cells_a.count(sig_data) || mux_cells_b.count(sig_data));
 
-			sig_data = sigmap(mux->getPort("\\Y"));
 			for (auto bit : sig_data)
 				if (sigbit_users_count[bit] > 1)
 					goto skip_ff_after_read_merging;
@@ -195,7 +201,7 @@ struct MemoryDffWorker
 			{
 				disconnect_dff(sig_data);
 				cell->setPort("\\CLK", clk_data);
-				cell->setPort("\\EN", enable_invert ? module->LogicNot(NEW_ID, mux->getPort("\\S")) : mux->getPort("\\S"));
+				cell->setPort("\\EN", en.size() > 1 ? module->ReduceAnd(NEW_ID, en) : en);
 				cell->setPort("\\DATA", sig_data);
 				cell->parameters["\\CLK_ENABLE"] = RTLIL::Const(1);
 				cell->parameters["\\CLK_POLARITY"] = RTLIL::Const(clk_polarity);
diff --git a/passes/opt/Makefile.inc b/passes/opt/Makefile.inc
index 337fee9e4..ea3646330 100644
--- a/passes/opt/Makefile.inc
+++ b/passes/opt/Makefile.inc
@@ -14,5 +14,6 @@ OBJS += passes/opt/opt_demorgan.o
 OBJS += passes/opt/rmports.o
 OBJS += passes/opt/opt_lut.o
 OBJS += passes/opt/pmux2shiftx.o
+OBJS += passes/opt/muxpack.o
 endif
 
diff --git a/passes/opt/muxpack.cc b/passes/opt/muxpack.cc
new file mode 100644
index 000000000..6697d6ca1
--- /dev/null
+++ b/passes/opt/muxpack.cc
@@ -0,0 +1,368 @@
+/*
+ *  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.
+ *
+ */
+
+#include "kernel/yosys.h"
+#include "kernel/sigtools.h"
+
+USING_YOSYS_NAMESPACE
+PRIVATE_NAMESPACE_BEGIN
+
+struct ExclusiveDatabase
+{
+	Module *module;
+	const SigMap &sigmap;
+
+	dict<SigBit, std::pair<SigSpec,std::vector<Const>>> sig_cmp_prev;
+
+	ExclusiveDatabase(Module *module, const SigMap &sigmap) : module(module), sigmap(sigmap)
+	{
+		SigSpec const_sig, nonconst_sig;
+		SigBit y_port;
+		pool<Cell*> reduce_or;
+		for (auto cell : module->cells()) {
+			if (cell->type == "$eq") {
+				nonconst_sig = sigmap(cell->getPort("\\A"));
+				const_sig = sigmap(cell->getPort("\\B"));
+				if (!const_sig.is_fully_const()) {
+					if (!nonconst_sig.is_fully_const())
+						continue;
+					std::swap(nonconst_sig, const_sig);
+				}
+				y_port = sigmap(cell->getPort("\\Y"));
+			}
+			else if (cell->type == "$logic_not") {
+				nonconst_sig = sigmap(cell->getPort("\\A"));
+				const_sig = Const(RTLIL::S0, GetSize(nonconst_sig));
+				y_port = sigmap(cell->getPort("\\Y"));
+			}
+			else if (cell->type == "$reduce_or") {
+				reduce_or.insert(cell);
+				continue;
+			}
+			else continue;
+
+			log_assert(!nonconst_sig.empty());
+			log_assert(!const_sig.empty());
+			sig_cmp_prev[y_port] = std::make_pair(nonconst_sig,std::vector<Const>{const_sig.as_const()});
+		}
+
+		for (auto cell : reduce_or) {
+			nonconst_sig = SigSpec();
+			std::vector<Const> values;
+			SigSpec a_port = sigmap(cell->getPort("\\A"));
+			for (auto bit : a_port) {
+				auto it = sig_cmp_prev.find(bit);
+				if (it == sig_cmp_prev.end()) {
+					nonconst_sig = SigSpec();
+					break;
+				}
+				if (nonconst_sig.empty())
+					nonconst_sig = it->second.first;
+				else if (nonconst_sig != it->second.first) {
+					nonconst_sig = SigSpec();
+					break;
+				}
+				for (auto value : it->second.second)
+					values.push_back(value);
+			}
+			if (nonconst_sig.empty())
+				continue;
+			y_port = sigmap(cell->getPort("\\Y"));
+			sig_cmp_prev[y_port] = std::make_pair(nonconst_sig,std::move(values));
+		}
+	}
+
+	bool query(const SigSpec &sig) const
+	{
+		SigSpec nonconst_sig;
+		pool<Const> const_values;
+
+		for (auto bit : sig.bits()) {
+			auto it = sig_cmp_prev.find(bit);
+			if (it == sig_cmp_prev.end())
+				return false;
+
+			if (nonconst_sig.empty())
+				nonconst_sig = it->second.first;
+			else if (nonconst_sig != it->second.first)
+				return false;
+
+			for (auto value : it->second.second)
+				if (!const_values.insert(value).second)
+					return false;
+		}
+
+		return true;
+	}
+};
+
+
+struct MuxpackWorker
+{
+	Module *module;
+	SigMap sigmap;
+
+	int mux_count, pmux_count;
+
+	pool<Cell*> remove_cells;
+
+	dict<SigSpec, Cell*> sig_chain_next;
+	dict<SigSpec, Cell*> sig_chain_prev;
+	pool<SigBit> sigbit_with_non_chain_users;
+	pool<Cell*> chain_start_cells;
+	pool<Cell*> candidate_cells;
+
+	ExclusiveDatabase excl_db;
+
+	void make_sig_chain_next_prev()
+	{
+		for (auto wire : module->wires())
+		{
+			if (wire->port_output || wire->get_bool_attribute("\\keep")) {
+				for (auto bit : sigmap(wire))
+					sigbit_with_non_chain_users.insert(bit);
+			}
+		}
+
+		for (auto cell : module->cells())
+		{
+			if (cell->type.in("$mux", "$pmux") && !cell->get_bool_attribute("\\keep"))
+			{
+				SigSpec a_sig = sigmap(cell->getPort("\\A"));
+				SigSpec b_sig;
+				if (cell->type == "$mux")
+					b_sig = sigmap(cell->getPort("\\B"));
+				SigSpec y_sig = sigmap(cell->getPort("\\Y"));
+   
+				if (sig_chain_next.count(a_sig))
+					for (auto a_bit : a_sig.bits())
+						sigbit_with_non_chain_users.insert(a_bit);
+				else {
+					sig_chain_next[a_sig] = cell;
+					candidate_cells.insert(cell);
+				}
+
+				if (!b_sig.empty()) {
+					if (sig_chain_next.count(b_sig))
+						for (auto b_bit : b_sig.bits())
+							sigbit_with_non_chain_users.insert(b_bit);
+					else {
+						sig_chain_next[b_sig] = cell;
+						candidate_cells.insert(cell);
+					}
+				}
+
+				sig_chain_prev[y_sig] = cell;
+				continue;
+			}
+
+			for (auto conn : cell->connections())
+				if (cell->input(conn.first))
+					for (auto bit : sigmap(conn.second))
+						sigbit_with_non_chain_users.insert(bit);
+		}
+	}
+
+	void find_chain_start_cells()
+	{
+		for (auto cell : candidate_cells)
+		{
+			log_debug("Considering %s (%s)\n", log_id(cell), log_id(cell->type));
+
+			SigSpec a_sig = sigmap(cell->getPort("\\A"));
+			if (cell->type == "$mux") {
+				SigSpec b_sig = sigmap(cell->getPort("\\B"));
+				if (sig_chain_prev.count(a_sig) + sig_chain_prev.count(b_sig) != 1)
+					goto start_cell;
+
+				if (!sig_chain_prev.count(a_sig))
+					a_sig = b_sig;
+			}
+			else if (cell->type == "$pmux") {
+				if (!sig_chain_prev.count(a_sig))
+					goto start_cell;
+			}
+			else log_abort();
+
+			for (auto bit : a_sig.bits())
+				if (sigbit_with_non_chain_users.count(bit))
+					goto start_cell;
+
+			{
+				Cell *prev_cell = sig_chain_prev.at(a_sig);
+				log_assert(prev_cell);
+				SigSpec s_sig = sigmap(cell->getPort("\\S"));
+				s_sig.append(sigmap(prev_cell->getPort("\\S")));
+				if (!excl_db.query(s_sig))
+					goto start_cell;
+			}
+
+			continue;
+
+		start_cell:
+			chain_start_cells.insert(cell);
+		}
+	}
+
+	vector<Cell*> create_chain(Cell *start_cell)
+	{
+		vector<Cell*> chain;
+
+		Cell *c = start_cell;
+		while (c != nullptr)
+		{
+			chain.push_back(c);
+
+			SigSpec y_sig = sigmap(c->getPort("\\Y"));
+
+			if (sig_chain_next.count(y_sig) == 0)
+				break;
+
+			c = sig_chain_next.at(y_sig);
+			if (chain_start_cells.count(c) != 0)
+				break;
+		}
+
+		return chain;
+	}
+
+	void process_chain(vector<Cell*> &chain)
+	{
+		if (GetSize(chain) < 2)
+			return;
+
+		int cursor = 0;
+		while (cursor < GetSize(chain))
+		{
+			int cases = GetSize(chain) - cursor;
+
+			Cell *first_cell = chain[cursor];
+			dict<int, SigBit> taps_dict;
+
+			if (cases < 2) {
+				cursor++;
+				continue;
+			}
+
+			Cell *last_cell = chain[cursor+cases-1];
+
+			log("Converting %s.%s ... %s.%s to a pmux with %d cases.\n",
+				log_id(module), log_id(first_cell), log_id(module), log_id(last_cell), cases);
+
+			mux_count += cases;
+			pmux_count += 1;
+
+			first_cell->type = "$pmux";
+			SigSpec b_sig = first_cell->getPort("\\B");
+			SigSpec s_sig = first_cell->getPort("\\S");
+
+			for (int i = 1; i < cases; i++) {
+				Cell* prev_cell = chain[cursor+i-1];
+				Cell* cursor_cell = chain[cursor+i];
+				if (sigmap(prev_cell->getPort("\\Y")) == sigmap(cursor_cell->getPort("\\A"))) {
+					b_sig.append(cursor_cell->getPort("\\B"));
+					s_sig.append(cursor_cell->getPort("\\S"));
+				}
+				else {
+					log_assert(cursor_cell->type == "$mux");
+					b_sig.append(cursor_cell->getPort("\\A"));
+					s_sig.append(module->LogicNot(NEW_ID, cursor_cell->getPort("\\S")));
+				}
+				remove_cells.insert(cursor_cell);
+			}
+
+			first_cell->setPort("\\B", b_sig);
+			first_cell->setPort("\\S", s_sig);
+			first_cell->setParam("\\S_WIDTH", GetSize(s_sig));
+			first_cell->setPort("\\Y", last_cell->getPort("\\Y"));
+
+			cursor += cases;
+		}
+	}
+
+	void cleanup()
+	{
+		for (auto cell : remove_cells)
+			module->remove(cell);
+
+		remove_cells.clear();
+		sig_chain_next.clear();
+		sig_chain_prev.clear();
+		chain_start_cells.clear();
+		candidate_cells.clear();
+	}
+
+	MuxpackWorker(Module *module) :
+			module(module), sigmap(module), mux_count(0), pmux_count(0), excl_db(module, sigmap)
+	{
+		make_sig_chain_next_prev();
+		find_chain_start_cells();
+
+		for (auto c : chain_start_cells) {
+			vector<Cell*> chain = create_chain(c);
+			process_chain(chain);
+		}
+
+		cleanup();
+	}
+};
+
+struct MuxpackPass : public Pass {
+	MuxpackPass() : Pass("muxpack", "$mux/$pmux cascades to $pmux") { }
+	void help() YS_OVERRIDE
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    muxpack [selection]\n");
+		log("\n");
+		log("This pass converts cascaded chains of $pmux cells (e.g. those create from case\n");
+		log("constructs) and $mux cells (e.g. those created by if-else constructs) into\n");
+		log("$pmux cells.\n");
+		log("\n");
+		log("This optimisation is conservative --- it will only pack $mux or $pmux cells\n");
+		log("whose select lines are driven by '$eq' cells with other such cells if it can be\n");
+		log("certain that their select inputs are mutually exclusive.\n");
+		log("\n");
+	}
+	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
+	{
+		log_header(design, "Executing MUXPACK pass ($mux cell cascades to $pmux).\n");
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++)
+		{
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		int mux_count = 0;
+		int pmux_count = 0;
+
+		for (auto module : design->selected_modules()) {
+			MuxpackWorker worker(module);
+			mux_count += worker.mux_count;
+			pmux_count += worker.pmux_count;
+		}
+
+		log("Converted %d (p)mux cells into %d pmux cells.\n", mux_count, pmux_count);
+	}
+} MuxpackPass;
+
+PRIVATE_NAMESPACE_END
diff --git a/passes/opt/opt.cc b/passes/opt/opt.cc
index a4aca2fee..e9a43e0f3 100644
--- a/passes/opt/opt.cc
+++ b/passes/opt/opt.cc
@@ -44,7 +44,7 @@ struct OptPass : public Pass {
 		log("        opt_muxtree\n");
 		log("        opt_reduce [-fine] [-full]\n");
 		log("        opt_merge [-share_all]\n");
-		log("        opt_rmdff [-keepdc]\n");
+		log("        opt_rmdff [-keepdc] [-sat]\n");
 		log("        opt_clean [-purge]\n");
 		log("        opt_expr [-mux_undef] [-mux_bool] [-undriven] [-clkinv] [-fine] [-full] [-keepdc]\n");
 		log("    while <changed design>\n");
@@ -54,7 +54,7 @@ struct OptPass : public Pass {
 		log("    do\n");
 		log("        opt_expr [-mux_undef] [-mux_bool] [-undriven] [-clkinv] [-fine] [-full] [-keepdc]\n");
 		log("        opt_merge [-share_all]\n");
-		log("        opt_rmdff [-keepdc]\n");
+		log("        opt_rmdff [-keepdc] [-sat]\n");
 		log("        opt_clean [-purge]\n");
 		log("    while <changed design in opt_rmdff>\n");
 		log("\n");
@@ -112,6 +112,10 @@ struct OptPass : public Pass {
 				opt_rmdff_args += " -keepdc";
 				continue;
 			}
+			if (args[argidx] == "-sat") {
+				opt_rmdff_args += " -sat";
+				continue;
+			}
 			if (args[argidx] == "-share_all") {
 				opt_merge_args += " -share_all";
 				continue;
diff --git a/passes/opt/opt_clean.cc b/passes/opt/opt_clean.cc
index cfb0f788a..a8a8e0bc7 100644
--- a/passes/opt/opt_clean.cc
+++ b/passes/opt/opt_clean.cc
@@ -326,8 +326,8 @@ bool rmunused_module_signals(RTLIL::Module *module, bool purge_mode, bool verbos
 		if (wire->port_id != 0 || wire->get_bool_attribute("\\keep") || !initval.is_fully_undef()) {
 			// do not delete anything with "keep" or module ports or initialized wires
 		} else
-		if (!purge_mode && check_public_name(wire->name)) {
-			// do not get rid of public names unless in purge mode
+		if (!purge_mode && check_public_name(wire->name) && (raw_used_signals.check_any(s1) || used_signals.check_any(s2) || s1 != s2)) {
+			// do not get rid of public names unless in purge mode or if the wire is entirely unused, not even aliased
 		} else
 		if (!raw_used_signals.check_any(s1)) {
 			// delete wires that aren't used by anything directly
@@ -480,7 +480,7 @@ void rmunused_module(RTLIL::Module *module, bool purge_mode, bool verbose, bool
 
 	std::vector<RTLIL::Cell*> delcells;
 	for (auto cell : module->cells())
-		if (cell->type.in("$pos", "$_BUF_")) {
+		if (cell->type.in("$pos", "$_BUF_") && !cell->has_keep_attr()) {
 			bool is_signed = cell->type == "$pos" && cell->getParam("\\A_SIGNED").as_bool();
 			RTLIL::SigSpec a = cell->getPort("\\A");
 			RTLIL::SigSpec y = cell->getPort("\\Y");
diff --git a/passes/opt/opt_rmdff.cc b/passes/opt/opt_rmdff.cc
index eeb992a3e..be6ac2d30 100644
--- a/passes/opt/opt_rmdff.cc
+++ b/passes/opt/opt_rmdff.cc
@@ -17,19 +17,24 @@
  *
  */
 
+#include "kernel/log.h"
 #include "kernel/register.h"
+#include "kernel/rtlil.h"
+#include "kernel/satgen.h"
 #include "kernel/sigtools.h"
-#include "kernel/log.h"
-#include <stdlib.h>
 #include <stdio.h>
+#include <stdlib.h>
 
 USING_YOSYS_NAMESPACE
 PRIVATE_NAMESPACE_BEGIN
 
 SigMap assign_map, dff_init_map;
 SigSet<RTLIL::Cell*> mux_drivers;
+dict<SigBit, RTLIL::Cell*> bit2driver;
 dict<SigBit, pool<SigBit>> init_attributes;
+
 bool keepdc;
+bool sat;
 
 void remove_init_attr(SigSpec sig)
 {
@@ -452,12 +457,84 @@ bool handle_dff(RTLIL::Module *mod, RTLIL::Cell *dff)
 		dff->unsetPort("\\E");
 	}
 
+	if (sat && has_init && (!sig_r.size() || val_init == val_rv))
+	{
+		bool removed_sigbits = false;
+
+		ezSatPtr ez;
+		SatGen satgen(ez.get(), &assign_map);
+		pool<Cell*> sat_cells;
+
+		std::function<void(Cell*)> sat_import_cell = [&](Cell *c) {
+			if (!sat_cells.insert(c).second)
+				return;
+			if (!satgen.importCell(c))
+				return;
+			for (auto &conn : c->connections()) {
+				if (!c->input(conn.first))
+					continue;
+				for (auto bit : assign_map(conn.second))
+					if (bit2driver.count(bit))
+						sat_import_cell(bit2driver.at(bit));
+			}
+		};
+
+		// For each register bit, try to prove that it cannot change from the initial value. If so, remove it
+		for (int position = 0; position < GetSize(sig_d); position += 1) {
+			RTLIL::SigBit q_sigbit = sig_q[position];
+			RTLIL::SigBit d_sigbit = sig_d[position];
+
+			if ((!q_sigbit.wire) || (!d_sigbit.wire))
+				continue;
+
+			if (!bit2driver.count(d_sigbit))
+				continue;
+
+			sat_import_cell(bit2driver.at(d_sigbit));
+
+			RTLIL::State sigbit_init_val = val_init[position];
+			if (sigbit_init_val != State::S0 && sigbit_init_val != State::S1)
+				continue;
+
+			int init_sat_pi = satgen.importSigSpec(sigbit_init_val).front();
+			int q_sat_pi = satgen.importSigBit(q_sigbit);
+			int d_sat_pi = satgen.importSigBit(d_sigbit);
+
+			// Try to find out whether the register bit can change under some circumstances
+			bool counter_example_found = ez->solve(ez->IFF(q_sat_pi, init_sat_pi), ez->NOT(ez->IFF(d_sat_pi, init_sat_pi)));
+
+			// If the register bit cannot change, we can replace it with a constant
+			if (!counter_example_found)
+			{
+				log("Setting constant %d-bit at position %d on %s (%s) from module %s.\n", sigbit_init_val ? 1 : 0,
+						position, log_id(dff), log_id(dff->type), log_id(mod));
+
+				SigSpec tmp = dff->getPort("\\D");
+				tmp[position] = sigbit_init_val;
+				dff->setPort("\\D", tmp);
+
+				removed_sigbits = true;
+			}
+		}
+
+		if (removed_sigbits) {
+			handle_dff(mod, dff);
+			return true;
+		}
+	}
+
+
 	return false;
 
 delete_dff:
 	log("Removing %s (%s) from module %s.\n", log_id(dff), log_id(dff->type), log_id(mod));
 	remove_init_attr(dff->getPort("\\Q"));
 	mod->remove(dff);
+
+	for (auto &entry : bit2driver)
+		if (entry.second == dff)
+			bit2driver.erase(entry.first);
+
 	return true;
 }
 
@@ -467,11 +544,15 @@ struct OptRmdffPass : public Pass {
 	{
 		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
 		log("\n");
-		log("    opt_rmdff [-keepdc] [selection]\n");
+		log("    opt_rmdff [-keepdc] [-sat] [selection]\n");
 		log("\n");
 		log("This pass identifies flip-flops with constant inputs and replaces them with\n");
 		log("a constant driver.\n");
 		log("\n");
+		log("    -sat\n");
+		log("        additionally invoke SAT solver to detect and remove flip-flops (with \n");
+		log("        non-constant inputs) that can also be replaced with a constant driver\n");
+		log("\n");
 	}
 	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
 	{
@@ -479,6 +560,7 @@ struct OptRmdffPass : public Pass {
 		log_header(design, "Executing OPT_RMDFF pass (remove dff with constant values).\n");
 
 		keepdc = false;
+		sat = false;
 
 		size_t argidx;
 		for (argidx = 1; argidx < args.size(); argidx++) {
@@ -486,18 +568,22 @@ struct OptRmdffPass : public Pass {
 				keepdc = true;
 				continue;
 			}
+			if (args[argidx] == "-sat") {
+				sat = true;
+				continue;
+			}
 			break;
 		}
 		extra_args(args, argidx, design);
 
-		for (auto module : design->selected_modules())
-		{
+		for (auto module : design->selected_modules()) {
 			pool<SigBit> driven_bits;
 			dict<SigBit, State> init_bits;
 
 			assign_map.set(module);
 			dff_init_map.set(module);
 			mux_drivers.clear();
+			bit2driver.clear();
 			init_attributes.clear();
 
 			for (auto wire : module->wires())
@@ -522,17 +608,21 @@ struct OptRmdffPass : public Pass {
 						driven_bits.insert(bit);
 				}
 			}
-			mux_drivers.clear();
 
 			std::vector<RTLIL::IdString> dff_list;
 			std::vector<RTLIL::IdString> dffsr_list;
 			std::vector<RTLIL::IdString> dlatch_list;
 			for (auto cell : module->cells())
 			{
-				for (auto &conn : cell->connections())
-					if (cell->output(conn.first) || !cell->known())
-						for (auto bit : assign_map(conn.second))
+				for (auto &conn : cell->connections()) {
+					bool is_output = cell->output(conn.first);
+					if (is_output || !cell->known())
+						for (auto bit : assign_map(conn.second)) {
+							if (is_output)
+								bit2driver[bit] = cell;
 							driven_bits.insert(bit);
+						}
+				}
 
 				if (cell->type == "$mux" || cell->type == "$pmux") {
 					if (cell->getPort("\\A").size() == cell->getPort("\\B").size())
@@ -604,6 +694,7 @@ struct OptRmdffPass : public Pass {
 
 		assign_map.clear();
 		mux_drivers.clear();
+		bit2driver.clear();
 		init_attributes.clear();
 
 		if (total_count || total_initdrv)
diff --git a/passes/opt/pmux2shiftx.cc b/passes/opt/pmux2shiftx.cc
index 29870f510..65d8b8f32 100644
--- a/passes/opt/pmux2shiftx.cc
+++ b/passes/opt/pmux2shiftx.cc
@@ -221,6 +221,9 @@ struct Pmux2ShiftxPass : public Pass {
 		log("        select strategy for one-hot encoded control signals\n");
 		log("        default: pmux\n");
 		log("\n");
+		log("    -norange\n");
+		log("        disable $sub inference for \"range decoders\"\n");
+		log("\n");
 	}
 	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
 	{
@@ -230,6 +233,7 @@ struct Pmux2ShiftxPass : public Pass {
 		bool optimize_onehot = true;
 		bool verbose = false;
 		bool verbose_onehot = false;
+		bool norange = false;
 
 		log_header(design, "Executing PMUX2SHIFTX pass.\n");
 
@@ -270,6 +274,10 @@ struct Pmux2ShiftxPass : public Pass {
 				verbose_onehot = true;
 				continue;
 			}
+			if (args[argidx] == "-norange") {
+				norange = true;
+				continue;
+			}
 			break;
 		}
 		extra_args(args, argidx, design);
@@ -559,7 +567,7 @@ struct Pmux2ShiftxPass : public Pass {
 								int this_inv_delta = this_maxval - this_minval;
 								bool this_inv = false;
 
-								if (this_delta != this_inv_delta)
+								if (!norange && this_delta != this_inv_delta)
 									this_inv = this_inv_delta < this_delta;
 								else if (this_maxval != this_inv_maxval)
 									this_inv = this_inv_maxval < this_maxval;
@@ -574,7 +582,7 @@ struct Pmux2ShiftxPass : public Pass {
 
 								if (best_src_col < 0)
 									this_is_better = true;
-								else if (this_delta != best_delta)
+								else if (!norange && this_delta != best_delta)
 									this_is_better = this_delta < best_delta;
 								else if (this_maxval != best_maxval)
 									this_is_better = this_maxval < best_maxval;
@@ -656,7 +664,7 @@ struct Pmux2ShiftxPass : public Pass {
 
 					// check density percentages
 					Const offset(State::S0, GetSize(sig));
-					if (absolute_density < min_density && range_density >= min_density)
+					if (!norange && absolute_density < min_density && range_density >= min_density)
 					{
 						offset = Const(min_choice, GetSize(sig));
 						log("    offset: %s\n", log_signal(offset));
diff --git a/passes/sat/assertpmux.cc b/passes/sat/assertpmux.cc
index 509cb0ba9..3b432c461 100644
--- a/passes/sat/assertpmux.cc
+++ b/passes/sat/assertpmux.cc
@@ -180,7 +180,7 @@ struct AssertpmuxWorker
 };
 
 struct AssertpmuxPass : public Pass {
-	AssertpmuxPass() : Pass("assertpmux", "convert internal signals to module ports") { }
+	AssertpmuxPass() : Pass("assertpmux", "adds asserts for parallel muxes") { }
 	void help() YS_OVERRIDE
 	{
 		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
@@ -195,8 +195,8 @@ struct AssertpmuxPass : public Pass {
 		log("\n");
 		log("    -always\n");
 		log("        usually the $pmux condition is only checked when the $pmux output\n");
-		log("        is used be the mux tree it drives. this option will deactivate this\n");
-		log("        additional constrained and check the $pmux condition always.\n");
+		log("        is used by the mux tree it drives. this option will deactivate this\n");
+		log("        additional constraint and check the $pmux condition always.\n");
 		log("\n");
 	}
 	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
diff --git a/passes/sat/cutpoint.cc b/passes/sat/cutpoint.cc
index 048aec7f3..b4549bc39 100644
--- a/passes/sat/cutpoint.cc
+++ b/passes/sat/cutpoint.cc
@@ -24,7 +24,7 @@ USING_YOSYS_NAMESPACE
 PRIVATE_NAMESPACE_BEGIN
 
 struct CutpointPass : public Pass {
-	CutpointPass() : Pass("cutpoint", "add hi/lo cover cells for each wire bit") { }
+	CutpointPass() : Pass("cutpoint", "adds formal cut points to the design") { }
 	void help() YS_OVERRIDE
 	{
 		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
diff --git a/passes/sat/sat.cc b/passes/sat/sat.cc
index cbba738f0..e4654d835 100644
--- a/passes/sat/sat.cc
+++ b/passes/sat/sat.cc
@@ -659,6 +659,7 @@ struct SatHelper
 
 	void dump_model_to_vcd(std::string vcd_file_name)
 	{
+		rewrite_filename(vcd_file_name);
 		FILE *f = fopen(vcd_file_name.c_str(), "w");
 		if (!f)
 			log_cmd_error("Can't open output file `%s' for writing: %s\n", vcd_file_name.c_str(), strerror(errno));
@@ -761,6 +762,7 @@ struct SatHelper
 
 	void dump_model_to_json(std::string json_file_name)
 	{
+		rewrite_filename(json_file_name);
 		FILE *f = fopen(json_file_name.c_str(), "w");
 		if (!f)
 			log_cmd_error("Can't open output file `%s' for writing: %s\n", json_file_name.c_str(), strerror(errno));
@@ -1505,6 +1507,7 @@ struct SatPass : public Pass {
 					{
 						if (!cnf_file_name.empty())
 						{
+							rewrite_filename(cnf_file_name);
 							FILE *f = fopen(cnf_file_name.c_str(), "w");
 							if (!f)
 								log_cmd_error("Can't open output file `%s' for writing: %s\n", cnf_file_name.c_str(), strerror(errno));
@@ -1608,6 +1611,7 @@ struct SatPass : public Pass {
 
 			if (!cnf_file_name.empty())
 			{
+				rewrite_filename(cnf_file_name);
 				FILE *f = fopen(cnf_file_name.c_str(), "w");
 				if (!f)
 					log_cmd_error("Can't open output file `%s' for writing: %s\n", cnf_file_name.c_str(), strerror(errno));
diff --git a/passes/techmap/Makefile.inc b/passes/techmap/Makefile.inc
index c45571b01..56f05eca4 100644
--- a/passes/techmap/Makefile.inc
+++ b/passes/techmap/Makefile.inc
@@ -10,6 +10,7 @@ OBJS += passes/techmap/abc.o
 OBJS += passes/techmap/abc9.o
 ifneq ($(ABCEXTERNAL),)
 passes/techmap/abc.o: CXXFLAGS += -DABCEXTERNAL='"$(ABCEXTERNAL)"'
+passes/techmap/abc9.o: CXXFLAGS += -DABCEXTERNAL='"$(ABCEXTERNAL)"'
 endif
 endif
 
diff --git a/passes/techmap/abc9.cc b/passes/techmap/abc9.cc
index f56350b1d..2eee43739 100644
--- a/passes/techmap/abc9.cc
+++ b/passes/techmap/abc9.cc
@@ -33,7 +33,7 @@
 #endif
 
 
-#define ABC_FAST_COMMAND_LUT "&st; &retime; &if {W}"
+#define ABC_FAST_COMMAND_LUT "&st; &if {W} {D}"
 
 #include "kernel/register.h"
 #include "kernel/sigtools.h"
@@ -80,8 +80,7 @@ void handle_loops(RTLIL::Design *design)
 {
 	Pass::call(design, "scc -set_attr abc_scc_id {}");
 
-	design->selection_stack.emplace_back(false);
-	RTLIL::Selection& sel = design->selection_stack.back();
+        dict<IdString, vector<IdString>> abc_scc_break;
 
 	// For every unique SCC found, (arbitrarily) find the first
 	// cell in the component, and select (and mark) all its output
@@ -92,24 +91,72 @@ void handle_loops(RTLIL::Design *design)
 		if (it != cell->attributes.end()) {
 			auto r = ids_seen.insert(it->second);
 			if (r.second) {
-				for (const auto &c : cell->connections()) {
+				for (auto &c : cell->connections_) {
 					if (c.second.is_fully_const()) continue;
 					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;
+						}
+						else {
+							log_assert(w->port_input);
+							log_assert(b.offset < GetSize(w));
+						}
 						w->set_bool_attribute("\\abc_scc_break");
-						sel.select(module, w);
+						module->swap_names(b.wire, w);
+						c.second = RTLIL::SigBit(w, b.offset);
 					}
 				}
 			}
 			cell->attributes.erase(it);
 		}
-	}
 
-	// Then cut those selected wires to expose them as new PO/PI
-	Pass::call(design, "expose -cut -sep .abc");
+		auto jt = abc_scc_break.find(cell->type);
+		if (jt == abc_scc_break.end()) {
+			std::vector<IdString> ports;
+			RTLIL::Module* box_module = design->module(cell->type);
+			if (box_module) {
+				auto ports_csv = box_module->attributes.at("\\abc_scc_break", RTLIL::Const::from_string("")).decode_string();
+				for (const auto &port_name : split_tokens(ports_csv, ",")) {
+					auto port_id = RTLIL::escape_id(port_name);
+					auto kt = cell->connections_.find(port_id);
+					if (kt == cell->connections_.end())
+						log_error("abc_scc_break attribute value '%s' does not exist as port on module '%s'\n", port_name.c_str(), log_id(box_module));
+					ports.push_back(port_id);
+				}
+			}
+			jt = abc_scc_break.insert(std::make_pair(cell->type, std::move(ports))).first;
+		}
+
+		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("\\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;
+		}
+	}
 
-	design->selection_stack.pop_back();
+	module->fixup_ports();
 }
 
 std::string add_echos_to_abc_cmd(std::string str)
@@ -380,9 +427,6 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
 		RTLIL::Selection& sel = design->selection_stack.back();
 		sel.select(module);
 
-		// Behave as for "abc" where BLIF writer implicitly outputs all undef as zero
-		Pass::call(design, "setundef -zero");
-
 		Pass::call(design, "aigmap");
 
 		handle_loops(design);
@@ -409,7 +453,7 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
 			reader.parse_xaiger();
 		}
 		ifs.close();
-		Pass::call(design, stringf("write_verilog -noexpr -norename %s/%s", tempdir_name.c_str(), "input.v"));
+		Pass::call(design, stringf("write_verilog -noexpr -norename"));
 		design->remove(design->module("$__abc9__"));
 #endif
 
@@ -482,7 +526,7 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
 		ifs.close();
 
 #if 0
-		Pass::call(design, stringf("write_verilog -noexpr -norename %s/%s", tempdir_name.c_str(), "output.v"));
+		Pass::call(design, stringf("write_verilog -noexpr -norename"));
 #endif
 
 		log_header(design, "Re-integrating ABC9 results.\n");
@@ -498,7 +542,7 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
 			if (w->port_output) {
 				RTLIL::Wire *wire = module->wire(w->name);
 				log_assert(wire);
-				for (int i = 0; i < GetSize(wire); i++)
+				for (int i = 0; i < GetSize(w); i++)
 					output_bits.insert({wire, i});
 			}
 
@@ -518,24 +562,28 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
 			signal = std::move(bits);
 		}
 
+		dict<IdString, bool> abc_box;
 		vector<RTLIL::Cell*> boxes;
-		for (auto it = module->cells_.begin(); it != module->cells_.end(); ) {
-			RTLIL::Cell* cell = it->second;
-			if (cell->type.in("$_AND_", "$_NOT_", "$__ABC_FF_")) {
-				it = module->remove(it);
+		for (const auto &it : module->cells_) {
+			auto cell = it.second;
+			if (cell->type.in("$_AND_", "$_NOT_")) {
+				module->remove(cell);
 				continue;
 			}
-			RTLIL::Module* box_module = design->module(cell->type);
-			if (box_module && box_module->attributes.count("\\abc_box_id"))
+			auto jt = abc_box.find(cell->type);
+			if (jt == abc_box.end()) {
+				RTLIL::Module* box_module = design->module(cell->type);
+				jt = abc_box.insert(std::make_pair(cell->type, box_module && box_module->attributes.count("\\abc_box_id"))).first;
+			}
+			if (jt->second)
 				boxes.emplace_back(cell);
-			++it;
 		}
 
 		std::map<std::string, int> cell_stats;
 		for (auto c : mapped_mod->cells())
 		{
+			RTLIL::Cell *cell = nullptr;
 			if (c->type == "$_NOT_") {
-				RTLIL::Cell *cell;
 				RTLIL::SigBit a_bit = c->getPort("\\A").as_bit();
 				RTLIL::SigBit y_bit = c->getPort("\\Y").as_bit();
 				if (!a_bit.wire) {
@@ -589,11 +637,12 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
 					cell->setPort("\\Y", RTLIL::SigBit(module->wires_[remap_name(y_bit.wire->name)], y_bit.offset));
 					cell_stats[RTLIL::unescape_id(c->type)]++;
 				}
-				if (markgroups) cell->attributes["\\abcgroup"] = map_autoidx;
+				if (cell && markgroups) cell->attributes["\\abcgroup"] = map_autoidx;
 				continue;
 			}
 			cell_stats[RTLIL::unescape_id(c->type)]++;
 
+                        RTLIL::Cell *existing_cell = nullptr;
 			if (c->type == "$lut") {
 				if (GetSize(c->getPort("\\A")) == 1 && c->getParam("\\LUT").as_int() == 2) {
 					SigSpec my_a = module->wires_[remap_name(c->getPort("\\A").as_wire()->name)];
@@ -602,19 +651,23 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
                                         if (markgroups) c->attributes["\\abcgroup"] = map_autoidx;
 					continue;
 				}
+				cell = module->addCell(remap_name(c->name), c->type);
+			}
+			else {
+				existing_cell = module->cell(c->name);
+				cell = module->addCell(remap_name(c->name), c->type);
+				module->swap_names(cell, existing_cell);
 			}
 
-			RTLIL::Cell *cell = module->addCell(remap_name(c->name), c->type);
 			if (markgroups) cell->attributes["\\abcgroup"] = map_autoidx;
-                        RTLIL::Cell *existing_cell = module->cell(c->name);
-                        if (existing_cell) {
-                                cell->parameters = existing_cell->parameters;
-                                cell->attributes = existing_cell->attributes;
-                        }
-                        else {
-                                cell->parameters = c->parameters;
-                                cell->attributes = c->attributes;
-                        }
+			if (existing_cell) {
+				cell->parameters = existing_cell->parameters;
+				cell->attributes = existing_cell->attributes;
+			}
+			else {
+				cell->parameters = c->parameters;
+				cell->attributes = c->attributes;
+			}
 			for (auto &conn : c->connections()) {
 				RTLIL::SigSpec newsig;
 				for (auto c : conn.second.chunks()) {
diff --git a/passes/techmap/muxcover.cc b/passes/techmap/muxcover.cc
index 32102436d..c84cfc39a 100644
--- a/passes/techmap/muxcover.cc
+++ b/passes/techmap/muxcover.cc
@@ -23,6 +23,7 @@
 USING_YOSYS_NAMESPACE
 PRIVATE_NAMESPACE_BEGIN
 
+#define COST_DMUX   90
 #define COST_MUX2  100
 #define COST_MUX4  220
 #define COST_MUX8  460
@@ -57,7 +58,9 @@ struct MuxcoverWorker
 	bool use_mux8;
 	bool use_mux16;
 	bool nodecode;
+	bool nopartial;
 
+	int cost_dmux;
 	int cost_mux2;
 	int cost_mux4;
 	int cost_mux8;
@@ -69,6 +72,8 @@ struct MuxcoverWorker
 		use_mux8 = false;
 		use_mux16 = false;
 		nodecode = false;
+		nopartial = false;
+		cost_dmux = COST_DMUX;
 		cost_mux2 = COST_MUX2;
 		cost_mux4 = COST_MUX4;
 		cost_mux8 = COST_MUX8;
@@ -76,6 +81,23 @@ struct MuxcoverWorker
 		decode_mux_counter = 0;
 	}
 
+	bool xcmp(std::initializer_list<SigBit> list)
+	{
+		auto cursor = list.begin(), end = list.end();
+		log_assert(cursor != end);
+		SigBit tmp = *(cursor++);
+		while (cursor != end) {
+			SigBit bit = *(cursor++);
+			if (bit == State::Sx)
+				continue;
+			if (tmp == State::Sx)
+				tmp = bit;
+			if (bit != tmp)
+				return false;
+		}
+		return true;
+	}
+
 	void treeify()
 	{
 		pool<SigBit> roots;
@@ -133,13 +155,22 @@ struct MuxcoverWorker
 		log("    Finished treeification: Found %d trees.\n", GetSize(tree_list));
 	}
 
-	bool follow_muxtree(SigBit &ret_bit, tree_t &tree, SigBit bit, const char *path)
+	bool follow_muxtree(SigBit &ret_bit, tree_t &tree, SigBit bit, const char *path, bool first_layer = true)
 	{
 		if (*path) {
-			if (tree.muxes.count(bit) == 0)
-				return false;
+			if (tree.muxes.count(bit) == 0) {
+				if (first_layer || nopartial)
+					return false;
+				while (path[0] && path[1])
+					path++;
+				if (path[0] == 'S')
+					ret_bit = State::Sx;
+				else
+					ret_bit = bit;
+				return true;
+			}
 			char port_name[3] = {'\\', *path, 0};
-			return follow_muxtree(ret_bit, tree, sigmap(tree.muxes.at(bit)->getPort(port_name)), path+1);
+			return follow_muxtree(ret_bit, tree, sigmap(tree.muxes.at(bit)->getPort(port_name)), path+1, false);
 		} else {
 			ret_bit = bit;
 			return true;
@@ -148,7 +179,7 @@ struct MuxcoverWorker
 
 	int prepare_decode_mux(SigBit &A, SigBit B, SigBit sel, SigBit bit)
 	{
-		if (A == B)
+		if (A == B || sel == State::Sx)
 			return 0;
 
 		tuple<SigBit, SigBit, SigBit> key(A, B, sel);
@@ -166,7 +197,10 @@ struct MuxcoverWorker
 		if (std::get<2>(entry))
 			return 0;
 
-		return cost_mux2 / GetSize(std::get<1>(entry));
+		if (A == State::Sx || B == State::Sx)
+			return 0;
+
+		return cost_dmux / GetSize(std::get<1>(entry));
 	}
 
 	void implement_decode_mux(SigBit ctrl_bit)
@@ -183,9 +217,32 @@ struct MuxcoverWorker
 		implement_decode_mux(std::get<0>(key));
 		implement_decode_mux(std::get<1>(key));
 
-		module->addMuxGate(NEW_ID, std::get<0>(key), std::get<1>(key), std::get<2>(key), ctrl_bit);
+		if (std::get<0>(key) == State::Sx) {
+			module->addBufGate(NEW_ID, std::get<1>(key), ctrl_bit);
+		} else if (std::get<1>(key) == State::Sx) {
+			module->addBufGate(NEW_ID, std::get<0>(key), ctrl_bit);
+		} else {
+			module->addMuxGate(NEW_ID, std::get<0>(key), std::get<1>(key), std::get<2>(key), ctrl_bit);
+			decode_mux_counter++;
+		}
 		std::get<2>(entry) = true;
-		decode_mux_counter++;
+	}
+
+	void find_best_covers(tree_t &tree, const vector<SigBit> &bits)
+	{
+		for (auto bit : bits)
+			find_best_cover(tree, bit);
+	}
+
+	int sum_best_covers(tree_t &tree, const vector<SigBit> &bits)
+	{
+		int sum = 0;
+		for (auto bit : pool<SigBit>(bits.begin(), bits.end())) {
+			int cost = tree.newmuxes.at(bit).cost;
+			log_debug("        Best cost for %s: %d\n", log_signal(bit), cost);
+			sum += cost;
+		}
+		return sum;
 	}
 
 	int find_best_cover(tree_t &tree, SigBit bit)
@@ -218,9 +275,13 @@ struct MuxcoverWorker
 			mux.inputs.push_back(B);
 			mux.selects.push_back(S1);
 
+			find_best_covers(tree, mux.inputs);
+			log_debug("        Decode cost for mux2 at %s: %d\n", log_signal(bit), mux.cost);
+
 			mux.cost += cost_mux2;
-			mux.cost += find_best_cover(tree, A);
-			mux.cost += find_best_cover(tree, B);
+			mux.cost += sum_best_covers(tree, mux.inputs);
+
+			log_debug("      Cost of mux2 at %s: %d\n", log_signal(bit), mux.cost);
 
 			best_mux = mux;
 		}
@@ -238,7 +299,7 @@ struct MuxcoverWorker
 			ok = ok && follow_muxtree(S2, tree, bit, "BS");
 
 			if (nodecode)
-				ok = ok && S1 == S2;
+				ok = ok && xcmp({S1, S2});
 
 			ok = ok && follow_muxtree(T1, tree, bit, "S");
 
@@ -256,13 +317,15 @@ struct MuxcoverWorker
 				mux.selects.push_back(S1);
 				mux.selects.push_back(T1);
 
+				find_best_covers(tree, mux.inputs);
+				log_debug("        Decode cost for mux4 at %s: %d\n", log_signal(bit), mux.cost);
+
 				mux.cost += cost_mux4;
-				mux.cost += find_best_cover(tree, A);
-				mux.cost += find_best_cover(tree, B);
-				mux.cost += find_best_cover(tree, C);
-				mux.cost += find_best_cover(tree, D);
+				mux.cost += sum_best_covers(tree, mux.inputs);
 
-				if (best_mux.cost > mux.cost)
+				log_debug("      Cost of mux4 at %s: %d\n", log_signal(bit), mux.cost);
+
+				if (best_mux.cost >= mux.cost)
 					best_mux = mux;
 			}
 		}
@@ -286,13 +349,13 @@ struct MuxcoverWorker
 			ok = ok && follow_muxtree(S4, tree, bit, "BBS");
 
 			if (nodecode)
-				ok = ok && S1 == S2 && S2 == S3 && S3 == S4;
+				ok = ok && xcmp({S1, S2, S3, S4});
 
 			ok = ok && follow_muxtree(T1, tree, bit, "AS");
 			ok = ok && follow_muxtree(T2, tree, bit, "BS");
 
 			if (nodecode)
-				ok = ok && T1 == T2;
+				ok = ok && xcmp({T1, T2});
 
 			ok = ok && follow_muxtree(U1, tree, bit, "S");
 
@@ -319,17 +382,15 @@ struct MuxcoverWorker
 				mux.selects.push_back(T1);
 				mux.selects.push_back(U1);
 
+				find_best_covers(tree, mux.inputs);
+				log_debug("        Decode cost for mux8 at %s: %d\n", log_signal(bit), mux.cost);
+
 				mux.cost += cost_mux8;
-				mux.cost += find_best_cover(tree, A);
-				mux.cost += find_best_cover(tree, B);
-				mux.cost += find_best_cover(tree, C);
-				mux.cost += find_best_cover(tree, D);
-				mux.cost += find_best_cover(tree, E);
-				mux.cost += find_best_cover(tree, F);
-				mux.cost += find_best_cover(tree, G);
-				mux.cost += find_best_cover(tree, H);
-
-				if (best_mux.cost > mux.cost)
+				mux.cost += sum_best_covers(tree, mux.inputs);
+
+				log_debug("      Cost of mux8 at %s: %d\n", log_signal(bit), mux.cost);
+
+				if (best_mux.cost >= mux.cost)
 					best_mux = mux;
 			}
 		}
@@ -365,7 +426,7 @@ struct MuxcoverWorker
 			ok = ok && follow_muxtree(S8, tree, bit, "BBBS");
 
 			if (nodecode)
-				ok = ok && S1 == S2 && S2 == S3 && S3 == S4 && S4 == S5 && S5 == S6 && S6 == S7 && S7 == S8;
+				ok = ok && xcmp({S1, S2, S3, S4, S5, S6, S7, S8});
 
 			ok = ok && follow_muxtree(T1, tree, bit, "AAS");
 			ok = ok && follow_muxtree(T2, tree, bit, "ABS");
@@ -373,13 +434,13 @@ struct MuxcoverWorker
 			ok = ok && follow_muxtree(T4, tree, bit, "BBS");
 
 			if (nodecode)
-				ok = ok && T1 == T2 && T2 == T3 && T3 == T4;
+				ok = ok && xcmp({T1, T2, T3, T4});
 
 			ok = ok && follow_muxtree(U1, tree, bit, "AS");
 			ok = ok && follow_muxtree(U2, tree, bit, "BS");
 
 			if (nodecode)
-				ok = ok && U1 == U2;
+				ok = ok && xcmp({U1, U2});
 
 			ok = ok && follow_muxtree(V1, tree, bit, "S");
 
@@ -423,25 +484,15 @@ struct MuxcoverWorker
 				mux.selects.push_back(U1);
 				mux.selects.push_back(V1);
 
+				find_best_covers(tree, mux.inputs);
+				log_debug("        Decode cost for mux16 at %s: %d\n", log_signal(bit), mux.cost);
+
 				mux.cost += cost_mux16;
-				mux.cost += find_best_cover(tree, A);
-				mux.cost += find_best_cover(tree, B);
-				mux.cost += find_best_cover(tree, C);
-				mux.cost += find_best_cover(tree, D);
-				mux.cost += find_best_cover(tree, E);
-				mux.cost += find_best_cover(tree, F);
-				mux.cost += find_best_cover(tree, G);
-				mux.cost += find_best_cover(tree, H);
-				mux.cost += find_best_cover(tree, I);
-				mux.cost += find_best_cover(tree, J);
-				mux.cost += find_best_cover(tree, K);
-				mux.cost += find_best_cover(tree, L);
-				mux.cost += find_best_cover(tree, M);
-				mux.cost += find_best_cover(tree, N);
-				mux.cost += find_best_cover(tree, O);
-				mux.cost += find_best_cover(tree, P);
-
-				if (best_mux.cost > mux.cost)
+				mux.cost += sum_best_covers(tree, mux.inputs);
+
+				log_debug("      Cost of mux16 at %s: %d\n", log_signal(bit), mux.cost);
+
+				if (best_mux.cost >= mux.cost)
 					best_mux = mux;
 			}
 		}
@@ -537,6 +588,7 @@ struct MuxcoverWorker
 	void treecover(tree_t &tree)
 	{
 		int count_muxes_by_type[4] = {0, 0, 0, 0};
+		log_debug("    Searching for best cover for tree at %s.\n", log_signal(tree.root));
 		find_best_cover(tree, tree.root);
 		implement_best_cover(tree, tree.root, count_muxes_by_type);
 		log("    Replaced tree at %s: %d MUX2, %d MUX4, %d MUX8, %d MUX16\n", log_signal(tree.root),
@@ -553,12 +605,13 @@ struct MuxcoverWorker
 
 		log("  Covering trees:\n");
 
-		// pre-fill cache of decoder muxes
-		if (!nodecode)
+		if (!nodecode) {
+			log_debug("    Populating cache of decoder muxes.\n");
 			for (auto &tree : tree_list) {
 				find_best_cover(tree, tree.root);
 				tree.newmuxes.clear();
 			}
+		}
 
 		for (auto &tree : tree_list)
 			treecover(tree);
@@ -584,11 +637,19 @@ struct MuxcoverPass : public Pass {
 		log("        Default costs: $_MUX_ = %d, $_MUX4_ = %d,\n", COST_MUX2, COST_MUX4);
 		log("                       $_MUX8_ = %d, $_MUX16_ = %d\n", COST_MUX8, COST_MUX16);
 		log("\n");
+		log("    -dmux=cost\n");
+		log("        Use the specified cost for $_MUX_ cells used in decoders.\n");
+		log("        Default cost: %d\n", COST_DMUX);
+		log("\n");
 		log("    -nodecode\n");
 		log("        Do not insert decoder logic. This reduces the number of possible\n");
 		log("        substitutions, but guarantees that the resulting circuit is not\n");
 		log("        less efficient than the original circuit.\n");
 		log("\n");
+		log("    -nopartial\n");
+		log("        Do not consider mappings that use $_MUX<N>_ to select from less\n");
+		log("        than <N> different signals.\n");
+		log("\n");
 	}
 	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
 	{
@@ -598,6 +659,8 @@ struct MuxcoverPass : public Pass {
 		bool use_mux8 = false;
 		bool use_mux16 = false;
 		bool nodecode = false;
+		bool nopartial = false;
+		int cost_dmux = COST_DMUX;
 		int cost_mux4 = COST_MUX4;
 		int cost_mux8 = COST_MUX8;
 		int cost_mux16 = COST_MUX16;
@@ -610,7 +673,7 @@ struct MuxcoverPass : public Pass {
 				use_mux4 = true;
 				if (arg.size() > 5) {
 					if (arg[5] != '=') break;
-					cost_mux4 = atoi(arg.substr(5).c_str());
+					cost_mux4 = atoi(arg.substr(6).c_str());
 				}
 				continue;
 			}
@@ -618,7 +681,7 @@ struct MuxcoverPass : public Pass {
 				use_mux8 = true;
 				if (arg.size() > 5) {
 					if (arg[5] != '=') break;
-					cost_mux8 = atoi(arg.substr(5).c_str());
+					cost_mux8 = atoi(arg.substr(6).c_str());
 				}
 				continue;
 			}
@@ -626,14 +689,22 @@ struct MuxcoverPass : public Pass {
 				use_mux16 = true;
 				if (arg.size() > 6) {
 					if (arg[6] != '=') break;
-					cost_mux16 = atoi(arg.substr(6).c_str());
+					cost_mux16 = atoi(arg.substr(7).c_str());
 				}
 				continue;
 			}
+			if (arg.size() >= 6 && arg.substr(0,6) == "-dmux=") {
+				cost_dmux = atoi(arg.substr(6).c_str());
+				continue;
+			}
 			if (arg == "-nodecode") {
 				nodecode = true;
 				continue;
 			}
+			if (arg == "-nopartial") {
+				nopartial = true;
+				continue;
+			}
 			break;
 		}
 		extra_args(args, argidx, design);
@@ -650,10 +721,12 @@ struct MuxcoverPass : public Pass {
 			worker.use_mux4 = use_mux4;
 			worker.use_mux8 = use_mux8;
 			worker.use_mux16 = use_mux16;
+			worker.cost_dmux = cost_dmux;
 			worker.cost_mux4 = cost_mux4;
 			worker.cost_mux8 = cost_mux8;
 			worker.cost_mux16 = cost_mux16;
 			worker.nodecode = nodecode;
+			worker.nopartial = nopartial;
 			worker.run();
 		}
 	}
diff --git a/passes/techmap/shregmap.cc b/passes/techmap/shregmap.cc
index 21dfe9619..004ab1eb9 100644
--- a/passes/techmap/shregmap.cc
+++ b/passes/techmap/shregmap.cc
@@ -293,10 +293,22 @@ struct ShregmapWorker
 
 				if (opts.init || sigbit_init.count(q_bit) == 0)
 				{
-					if (sigbit_chain_next.count(d_bit)) {
+					auto r = sigbit_chain_next.insert(std::make_pair(d_bit, cell));
+					if (!r.second) {
+						// Insertion not successful means that d_bit is already
+						// connected to another register, thus mark it as a
+						// non chain user ...
 						sigbit_with_non_chain_users.insert(d_bit);
-					} else
-						sigbit_chain_next[d_bit] = cell;
+						// ... and clone d_bit into another wire, and use that
+						// wire as a different key in the d_bit-to-cell dictionary
+						// so that it can be identified as another chain
+						// (omitting this common flop)
+						// Link: https://github.com/YosysHQ/yosys/pull/1085
+						Wire *wire = module->addWire(NEW_ID);
+						module->connect(wire, d_bit);
+						sigmap.add(wire, d_bit);
+						sigbit_chain_next.insert(std::make_pair(wire, cell));
+					}
 
 					sigbit_chain_prev[q_bit] = cell;
 					continue;
@@ -605,9 +617,11 @@ struct ShregmapPass : public Pass {
 		log("\n");
 		log("    -tech greenpak4\n");
 		log("        map to greenpak4 shift registers.\n");
+		log("        this option also implies -clkpol pos -zinit\n");
 		log("\n");
 		log("    -tech xilinx\n");
 		log("        map to xilinx dynamic-length shift registers.\n");
+		log("        this option also implies -params -init\n");
 		log("\n");
 	}
 	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
diff --git a/techlibs/ecp5/Makefile.inc b/techlibs/ecp5/Makefile.inc
index eee3b418f..ff39ba4fe 100644
--- a/techlibs/ecp5/Makefile.inc
+++ b/techlibs/ecp5/Makefile.inc
@@ -13,6 +13,7 @@ $(eval $(call add_share_file,share/ecp5,techlibs/ecp5/latches_map.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))
 
 EXTRA_OBJS += techlibs/ecp5/brams_init.mk techlibs/ecp5/brams_connect.mk
 .SECONDARY: techlibs/ecp5/brams_init.mk techlibs/ecp5/brams_connect.mk
diff --git a/techlibs/ecp5/abc_5g.box b/techlibs/ecp5/abc_5g.box
index 72af6d9cb..c757d137d 100644
--- a/techlibs/ecp5/abc_5g.box
+++ b/techlibs/ecp5/abc_5g.box
@@ -1,5 +1,12 @@
+# NB: Inputs/Outputs must be ordered alphabetically
+#     (with exceptions for carry in/out)
+
 # Box 1 : CCU2C (2xCARRY + 2xLUT4)
 # Outputs: S0, S1, COUT
+#   (NB: carry chain input/output must be last
+#        input/output and bus has been moved
+#        there overriding the otherwise
+#        alphabetical ordering)
 # name  ID   w/b   ins    outs
 CCU2C   1      1   9      3
 
@@ -9,7 +16,7 @@ CCU2C   1      1   9      3
 516  516  516  516  412   412  278  278  43
 
 # Box 2 : TRELLIS_DPR16X4 (16x4 dist ram)
-# Outputs: DO0, DO1, DO2, DO3, DO4
+# Outputs: DO0, DO1, DO2, DO3
 # name            ID  w/b   ins   outs
 TRELLIS_DPR16X4   2     0   14    4
 
diff --git a/techlibs/ecp5/abc_5g_nowide.lut b/techlibs/ecp5/abc_5g_nowide.lut
new file mode 100644
index 000000000..60352d892
--- /dev/null
+++ b/techlibs/ecp5/abc_5g_nowide.lut
@@ -0,0 +1,12 @@
+# ECP5-5G LUT library for ABC
+# Note that ECP5 architecture assigns difference
+# in LUT input delay to interconnect, so this is
+# considered too
+
+
+# Simple LUTs
+#  area  D    C    B    A
+1  1     141
+2  1     141  275
+3  1     141  275  379
+4  1     141  275  379  379
diff --git a/techlibs/ecp5/arith_map.v b/techlibs/ecp5/arith_map.v
index eb7947601..17bde0497 100644
--- a/techlibs/ecp5/arith_map.v
+++ b/techlibs/ecp5/arith_map.v
@@ -50,20 +50,21 @@ module _80_ecp5_alu (A, B, CI, BI, X, Y, CO);
 
 	wire [Y_WIDTH2-1:0] AA = A_buf;
 	wire [Y_WIDTH2-1:0] BB = BI ? ~B_buf : B_buf;
+	wire [Y_WIDTH2-1:0] BX = B_buf;
 	wire [Y_WIDTH2-1:0] C = {CO, CI};
 	wire [Y_WIDTH2-1:0] FCO, Y1;
 
 	genvar i;
 	generate for (i = 0; i < Y_WIDTH2; i = i + 2) begin:slice
 		CCU2C #(
-			.INIT0(16'b0110011010101010),
-			.INIT1(16'b0110011010101010),
+			.INIT0(16'b1001011010101010),
+			.INIT1(16'b1001011010101010),
 			.INJECT1_0("NO"),
 			.INJECT1_1("NO")
 	   ) ccu2c_i (
 			.CIN(C[i]),
-			.A0(AA[i]), .B0(BB[i]), .C0(1'b0), .D0(1'b1),
-			.A1(AA[i+1]), .B1(BB[i+1]), .C1(1'b0), .D1(1'b1),
+			.A0(AA[i]), .B0(BX[i]), .C0(BI), .D0(1'b1),
+			.A1(AA[i+1]), .B1(BX[i+1]), .C1(BI), .D1(1'b1),
 			.S0(Y[i]), .S1(Y1[i]),
 			.COUT(FCO[i])
 		);
diff --git a/techlibs/ecp5/cells_map.v b/techlibs/ecp5/cells_map.v
index 53a89e8a3..6985fbbc8 100644
--- a/techlibs/ecp5/cells_map.v
+++ b/techlibs/ecp5/cells_map.v
@@ -47,6 +47,28 @@ module  \$__DFFSE_NP1 (input D, C, E, R, output Q); TRELLIS_FF #(.GSR("DISABLED"
 module  \$__DFFSE_PP0 (input D, C, E, R, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("CE"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("RESET"), .SRMODE("LSR_OVER_CE"))  _TECHMAP_REPLACE_ (.CLK(C), .CE(E), .LSR(R), .DI(D), .Q(Q)); endmodule
 module  \$__DFFSE_PP1 (input D, C, E, R, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("CE"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("SET"), .SRMODE("LSR_OVER_CE"))  _TECHMAP_REPLACE_ (.CLK(C), .CE(E), .LSR(R), .DI(D), .Q(Q)); endmodule
 
+// TODO: Diamond flip-flops
+// module FD1P3AX(); endmodule
+// module FD1P3AY(); endmodule
+// module FD1P3BX(); endmodule
+// module FD1P3DX(); endmodule
+// module FD1P3IX(); endmodule
+// module FD1P3JX(); endmodule
+// module FD1S3AX(); endmodule
+// module FD1S3AY(); endmodule
+module FD1S3BX(input PD, D, CK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("SET"), .SRMODE("ASYNC"))  _TECHMAP_REPLACE_ (.CLK(CK), .LSR(PD), .DI(D), .Q(Q)); endmodule
+module FD1S3DX(input CD, D, CK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("RESET"), .SRMODE("ASYNC"))  _TECHMAP_REPLACE_ (.CLK(CK), .LSR(CD), .DI(D), .Q(Q)); endmodule
+module FD1S3IX(input CD, D, CK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("RESET"), .SRMODE("LSR_OVER_CE"))  _TECHMAP_REPLACE_ (.CLK(CK), .LSR(CD), .DI(D), .Q(Q)); endmodule
+module FD1S3JX(input PD, D, CK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("SET"), .SRMODE("LSR_OVER_CE"))  _TECHMAP_REPLACE_ (.CLK(CK), .LSR(PD), .DI(D), .Q(Q)); endmodule
+// module FL1P3AY(); endmodule
+// module FL1P3AZ(); endmodule
+// module FL1P3BX(); endmodule
+// module FL1P3DX(); endmodule
+// module FL1P3IY(); endmodule
+// module FL1P3JY(); endmodule
+// module FL1S3AX(); endmodule
+// module FL1S3AY(); endmodule
+
 // Diamond I/O buffers
 module IB   (input I, output O); (* PULLMODE="NONE" *) TRELLIS_IO #(.DIR("INPUT")) _TECHMAP_REPLACE_ (.B(I), .O(O)); endmodule
 module IBPU (input I, output O); (* PULLMODE="UP"   *) TRELLIS_IO #(.DIR("INPUT"))   _TECHMAP_REPLACE_ (.B(I), .O(O)); endmodule
@@ -62,14 +84,30 @@ module BBPD (input I, T, output O, inout B); (* PULLMODE="DOWN" *) TRELLIS_IO #(
 module ILVDS(input A, AN, output Z); TRELLIS_IO #(.DIR("INPUT"))  _TECHMAP_REPLACE_ (.B(A), .O(Z)); endmodule
 module OLVDS(input A, output Z, ZN); TRELLIS_IO #(.DIR("OUTPUT")) _TECHMAP_REPLACE_ (.B(Z), .I(A)); endmodule
 
-// For Diamond compatibility, FIXME: add all Diamond flipflop mappings
-module FD1S3BX(input PD, D, CK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("SET"), .SRMODE("ASYNC"))  _TECHMAP_REPLACE_ (.CLK(CK), .LSR(PD), .DI(D), .Q(Q)); endmodule
+// Diamond I/O registers
+module IFS1P3BX(input PD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("SET"), .SRMODE("ASYNC"))  _TECHMAP_REPLACE_ (.CLK(SCLK), .LSR(PD), .CE(SP), .DI(D), .Q(Q)); endmodule
+module IFS1P3DX(input CD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("RESET"), .SRMODE("ASYNC"))  _TECHMAP_REPLACE_ (.CLK(SCLK), .LSR(CD), .CE(SP), .DI(D), .Q(Q)); endmodule
+module IFS1P3IX(input CD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("RESET"), .SRMODE("LSR_OVER_CE"))  _TECHMAP_REPLACE_ (.CLK(SCLK), .LSR(CD), .CE(SP), .DI(D), .Q(Q)); endmodule
+module IFS1P3JX(input PD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("SET"), .SRMODE("LSR_OVER_CE"))  _TECHMAP_REPLACE_ (.CLK(SCLK), .LSR(PD), .CE(SP), .DI(D), .Q(Q)); endmodule
+
+module OFS1P3BX(input PD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("SET"), .SRMODE("ASYNC"))  _TECHMAP_REPLACE_ (.CLK(SCLK), .LSR(PD), .CE(SP), .DI(D), .Q(Q)); endmodule
+module OFS1P3DX(input CD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("RESET"), .SRMODE("ASYNC"))  _TECHMAP_REPLACE_ (.CLK(SCLK), .LSR(CD), .CE(SP), .DI(D), .Q(Q)); endmodule
+module OFS1P3IX(input CD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("RESET"), .SRMODE("LSR_OVER_CE"))  _TECHMAP_REPLACE_ (.CLK(SCLK), .LSR(CD), .CE(SP), .DI(D), .Q(Q)); endmodule
+module OFS1P3JX(input PD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("SET"), .SRMODE("LSR_OVER_CE"))  _TECHMAP_REPLACE_ (.CLK(SCLK), .LSR(PD), .CE(SP), .DI(D), .Q(Q)); endmodule
+
+// TODO: Diamond I/O latches
+// module IFS1S1B(input PD, D, SCLK, output Q); endmodule
+// module IFS1S1D(input CD, D, SCLK, output Q); endmodule
+// module IFS1S1I(input PD, D, SCLK, output Q); endmodule
+// module IFS1S1J(input CD, D, SCLK, output Q); endmodule
 
 `ifndef NO_LUT
 module \$lut (A, Y);
     parameter WIDTH = 0;
     parameter LUT = 0;
 
+    input [WIDTH-1:0] A;
+    output Y;
 
     // Need to swap input ordering, and fix init accordingly,
     // to match ABC's expectation of LUT inputs in non-decreasing
@@ -86,19 +124,15 @@ module \$lut (A, Y);
     endfunction
 
     function [2**P_WIDTH-1:0] permute_init;
-        input [2**P_WIDTH-1:0] orig;
         integer i;
         begin
             permute_init = 0;
             for (i = 0; i < 2**P_WIDTH; i = i + 1)
-                permute_init[i] = orig[permute_index(i)];
+                permute_init[i] = LUT[permute_index(i)];
         end
     endfunction
 
-    parameter [2**P_WIDTH-1:0] P_LUT = permute_init(LUT);
-
-    input [WIDTH-1:0] A;
-    output Y;
+    parameter [2**P_WIDTH-1:0] P_LUT = permute_init();
 
     generate
         if (WIDTH == 1) begin
diff --git a/techlibs/ecp5/cells_sim.v b/techlibs/ecp5/cells_sim.v
index f66147323..ca88d0a5b 100644
--- a/techlibs/ecp5/cells_sim.v
+++ b/techlibs/ecp5/cells_sim.v
@@ -15,11 +15,9 @@ module L6MUX21 (input D0, D1, SD, output Z);
 endmodule
 
 // ---------------------------------------
-(* abc_box_id=1, abc_carry, lib_whitebox *)
-module CCU2C((* abc_carry_in *) input CIN,
-			   input A0, B0, C0, D0, A1, B1, C1, D1,
-	           output S0, S1,
-	         (* abc_carry_out *) output COUT);
+(* abc_box_id=1, abc_carry="CIN,COUT", lib_whitebox *)
+module CCU2C(input CIN, A0, B0, C0, D0, A1, B1, C1, D1,
+	           output S0, S1, COUT);
 
 	parameter [15:0] INIT0 = 16'h0000;
 	parameter [15:0] INIT1 = 16'h0000;
@@ -106,7 +104,7 @@ module PFUMX (input ALUT, BLUT, C0, output Z);
 endmodule
 
 // ---------------------------------------
-//(* abc_box_id=2 *)
+//(* abc_box_id=2, abc_scc_break="DI,WAD,WRE" *)
 module TRELLIS_DPR16X4 (
 	input [3:0] DI,
 	input [3:0] WAD,
@@ -261,18 +259,6 @@ module TRELLIS_FF(input CLK, LSR, CE, DI, M, output reg Q);
 endmodule
 
 // ---------------------------------------
-
-module OBZ(input I, T, output O);
-assign O = T ? 1'bz : I;
-endmodule
-
-// ---------------------------------------
-
-module IB(input I, output O);
-assign O = I;
-endmodule
-
-// ---------------------------------------
 (* keep *)
 module TRELLIS_IO(
 	inout B,
@@ -303,19 +289,6 @@ endmodule
 
 // ---------------------------------------
 
-module OB(input I, output O);
-assign O = I;
-endmodule
-
-// ---------------------------------------
-
-module BB(input I, T, output O, inout B);
-assign B = T ? 1'bz : I;
-assign O = B;
-endmodule
-
-// ---------------------------------------
-
 module INV(input A, output Z);
 	assign Z = !A;
 endmodule
@@ -568,19 +541,56 @@ module DP16KD(
   parameter INITVAL_3F = 320'h00000000000000000000000000000000000000000000000000000000000000000000000000000000;
 endmodule
 
-// For Diamond compatibility, FIXME: add all Diamond flipflop mappings
-module FD1S3BX(input PD, D, CK, output Q);
-	TRELLIS_FF #(
-		.GSR("DISABLED"),
-		.CEMUX("1"),
-		.CLKMUX("CLK"),
-		.LSRMUX("LSR"),
-		.REGSET("SET"),
-		.SRMODE("ASYNC")
-	) tff_i (
-		.CLK(CK),
-		.LSR(PD),
-		.DI(D),
-		.Q(Q)
-	);
-endmodule
+// TODO: Diamond flip-flops
+// module FD1P3AX(); endmodule
+// module FD1P3AY(); endmodule
+// module FD1P3BX(); endmodule
+// module FD1P3DX(); endmodule
+// module FD1P3IX(); endmodule
+// module FD1P3JX(); endmodule
+// module FD1S3AX(); endmodule
+// module FD1S3AY(); endmodule
+module FD1S3BX(input PD, D, CK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("SET"), .SRMODE("ASYNC"))  tff (.CLK(CK), .LSR(PD), .DI(D), .Q(Q)); endmodule
+module FD1S3DX(input CD, D, CK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("RESET"), .SRMODE("ASYNC"))  tff (.CLK(CK), .LSR(CD), .DI(D), .Q(Q)); endmodule
+module FD1S3IX(input CD, D, CK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("RESET"), .SRMODE("LSR_OVER_CE"))  tff (.CLK(CK), .LSR(CD), .DI(D), .Q(Q)); endmodule
+module FD1S3JX(input PD, D, CK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("SET"), .SRMODE("LSR_OVER_CE"))  tff (.CLK(CK), .LSR(PD), .DI(D), .Q(Q)); endmodule
+// module FL1P3AY(); endmodule
+// module FL1P3AZ(); endmodule
+// module FL1P3BX(); endmodule
+// module FL1P3DX(); endmodule
+// module FL1P3IY(); endmodule
+// module FL1P3JY(); endmodule
+// module FL1S3AX(); endmodule
+// module FL1S3AY(); endmodule
+
+// Diamond I/O buffers
+module IB   (input I, output O); (* PULLMODE="NONE" *) TRELLIS_IO #(.DIR("INPUT")) tio (.B(I), .O(O)); endmodule
+module IBPU (input I, output O); (* PULLMODE="UP"   *) TRELLIS_IO #(.DIR("INPUT"))   tio (.B(I), .O(O)); endmodule
+module IBPD (input I, output O); (* PULLMODE="DOWN" *) TRELLIS_IO #(.DIR("INPUT")) tio (.B(I), .O(O)); endmodule
+module OB   (input I, output O); (* PULLMODE="NONE" *) TRELLIS_IO #(.DIR("OUTPUT")) tio (.B(O), .I(I)); endmodule
+module OBZ  (input I, T, output O); (* PULLMODE="NONE" *) TRELLIS_IO #(.DIR("OUTPUT")) tio (.B(O), .I(I), .T(T)); endmodule
+module OBZPU(input I, T, output O); (* PULLMODE="UP"   *) TRELLIS_IO #(.DIR("OUTPUT"))   tio (.B(O), .I(I), .T(T)); endmodule
+module OBZPD(input I, T, output O); (* PULLMODE="DOWN" *) TRELLIS_IO #(.DIR("OUTPUT")) tio (.B(O), .I(I), .T(T)); endmodule
+module OBCO (input I, output OT, OC); OLVDS olvds (.A(I), .Z(OT), .ZN(OC)); endmodule
+module BB   (input I, T, output O, inout B); (* PULLMODE="NONE" *) TRELLIS_IO #(.DIR("BIDIR")) tio (.B(B), .I(I), .O(O), .T(T)); endmodule
+module BBPU (input I, T, output O, inout B); (* PULLMODE="UP"   *) TRELLIS_IO #(.DIR("BIDIR"))   tio (.B(B), .I(I), .O(O), .T(T)); endmodule
+module BBPD (input I, T, output O, inout B); (* PULLMODE="DOWN" *) TRELLIS_IO #(.DIR("BIDIR")) tio (.B(B), .I(I), .O(O), .T(T)); endmodule
+module ILVDS(input A, AN, output Z); TRELLIS_IO #(.DIR("INPUT"))  tio (.B(A), .O(Z)); endmodule
+module OLVDS(input A, output Z, ZN); TRELLIS_IO #(.DIR("OUTPUT")) tio (.B(Z), .I(A)); endmodule
+
+// Diamond I/O registers
+module IFS1P3BX(input PD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("SET"), .SRMODE("ASYNC"))  tff (.CLK(SCLK), .LSR(PD), .CE(SP), .DI(D), .Q(Q)); endmodule
+module IFS1P3DX(input CD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("RESET"), .SRMODE("ASYNC"))  tff (.CLK(SCLK), .LSR(CD), .CE(SP), .DI(D), .Q(Q)); endmodule
+module IFS1P3IX(input CD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("RESET"), .SRMODE("LSR_OVER_CE"))  tff (.CLK(SCLK), .LSR(CD), .CE(SP), .DI(D), .Q(Q)); endmodule
+module IFS1P3JX(input PD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("SET"), .SRMODE("LSR_OVER_CE"))  tff (.CLK(SCLK), .LSR(PD), .CE(SP), .DI(D), .Q(Q)); endmodule
+
+module OFS1P3BX(input PD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("SET"), .SRMODE("ASYNC"))  tff (.CLK(SCLK), .LSR(PD), .CE(SP), .DI(D), .Q(Q)); endmodule
+module OFS1P3DX(input CD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("RESET"), .SRMODE("ASYNC"))  tff (.CLK(SCLK), .LSR(CD), .CE(SP), .DI(D), .Q(Q)); endmodule
+module OFS1P3IX(input CD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("RESET"), .SRMODE("LSR_OVER_CE"))  tff (.CLK(SCLK), .LSR(CD), .CE(SP), .DI(D), .Q(Q)); endmodule
+module OFS1P3JX(input PD, D, SP, SCLK, output Q); TRELLIS_FF #(.GSR("DISABLED"), .CEMUX("1"), .CLKMUX("CLK"), .LSRMUX("LSR"), .REGSET("SET"), .SRMODE("LSR_OVER_CE"))  tff (.CLK(SCLK), .LSR(PD), .CE(SP), .DI(D), .Q(Q)); endmodule
+
+// TODO: Diamond I/O latches
+// module IFS1S1B(input PD, D, SCLK, output Q); endmodule
+// module IFS1S1D(input CD, D, SCLK, output Q); endmodule
+// module IFS1S1I(input PD, D, SCLK, output Q); endmodule
+// module IFS1S1J(input CD, D, SCLK, output Q); endmodule
diff --git a/techlibs/ecp5/synth_ecp5.cc b/techlibs/ecp5/synth_ecp5.cc
index b271500f1..f16a47f01 100644
--- a/techlibs/ecp5/synth_ecp5.cc
+++ b/techlibs/ecp5/synth_ecp5.cc
@@ -76,7 +76,7 @@ struct SynthEcp5Pass : public ScriptPass
 		log("    -nodram\n");
 		log("        do not use distributed RAM cells in output netlist\n");
 		log("\n");
-		log("    -nomux\n");
+		log("    -nowidelut\n");
 		log("        do not use PFU muxes to implement LUTs larger than LUT4s\n");
 		log("\n");
 		log("    -abc2\n");
@@ -96,7 +96,7 @@ struct SynthEcp5Pass : public ScriptPass
 	}
 
 	string top_opt, blif_file, edif_file, json_file;
-	bool noccu2, nodffe, nobram, nodram, nomux, flatten, retime, abc2, abc9, vpr;
+	bool noccu2, nodffe, nobram, nodram, nowidelut, flatten, retime, abc2, abc9, vpr;
 
 	void clear_flags() YS_OVERRIDE
 	{
@@ -108,7 +108,7 @@ struct SynthEcp5Pass : public ScriptPass
 		nodffe = false;
 		nobram = false;
 		nodram = false;
-		nomux = false;
+		nowidelut = false;
 		flatten = true;
 		retime = false;
 		abc2 = false;
@@ -176,8 +176,8 @@ struct SynthEcp5Pass : public ScriptPass
 				nodram = true;
 				continue;
 			}
-			if (args[argidx] == "-nomux") {
-				nomux = true;
+			if (args[argidx] == "-nowidelut" || args[argidx] == "-nomux") {
+				nowidelut = true;
 				continue;
 			}
 			if (args[argidx] == "-abc2") {
@@ -273,14 +273,16 @@ struct SynthEcp5Pass : public ScriptPass
 			}
 			run("techmap -map +/ecp5/latches_map.v");
 			if (abc9) {
-				run("abc9 -lut +/ecp5/abc_5g.lut -box +/ecp5/abc_5g.box -W 200");
+				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");
 			} else {
-				if (nomux)
+				if (nowidelut)
 					run("abc -lut 4 -dress");
 				else
 					run("abc -lut 4:7 -dress");
 			}
-
 			run("clean");
 		}
 
diff --git a/techlibs/ice40/abc_hx.box b/techlibs/ice40/abc_hx.box
index a0655643d..f8e12b527 100644
--- a/techlibs/ice40/abc_hx.box
+++ b/techlibs/ice40/abc_hx.box
@@ -1,113 +1,17 @@
 # From https://github.com/cliffordwolf/icestorm/blob/be0bca0/icefuzz/timings_hx8k.txt
 
 # NB: Inputs/Outputs must be ordered alphabetically
+#     (with exceptions for carry in/out)
 
-# Inputs: C D
-# Outputs: Q
-SB_DFF 1 0 2 1
-- -
-
-# Inputs: C D E
-# Outputs: Q
-SB_DFFE 2 0 3 1
-- - -
-
-# Inputs: C D R
-# Outputs: Q
-SB_DFFSR 3 0 3 1
-- - -
-
-# Inputs: C D R
-# Outputs: Q
-SB_DFFR 4 0 3 1
-- - -
-
-# Inputs: C D S
-# Outputs: Q
-SB_DFFSS 5 0 3 1
-- - -
-
-# Inputs: C D S
-# Outputs: Q
-SB_DFFS 6 0 3 1
-- - -
-
-# Inputs: C D E R
-# Outputs: Q
-SB_DFFESR 7 0 4 1
-- - - -
-
-# Inputs: C D E R
-# Outputs: Q
-SB_DFFER 8 0 4 1
-- - - -
-
-# Inputs: C D E S
-# Outputs: Q
-SB_DFFESS 9 0 4 1
-- - - -
-
-# Inputs: C D E S
-# Outputs: Q
-SB_DFFES 10 0 4 1
-- - - -
-
-# Inputs: C D
-# Outputs: Q
-SB_DFFN 11 0 2 1
-- -
-
-# Inputs: C D E
-# Outputs: Q
-SB_DFFNE 12 0 3 1
-- - -
-
-# Inputs: C D R
-# Outputs: Q
-SB_DFFNSR 13 0 3 1
-- - -
-
-# Inputs: C D R
-# Outputs: Q
-SB_DFFNR 14 0 3 1
-- - -
-
-# Inputs: C D S
-# Outputs: Q
-SB_DFFNSS 15 0 3 1
-- - -
-
-# Inputs: C D S
-# Outputs: Q
-SB_DFFNS 16 0 3 1
-- - -
-
-# Inputs: C D E R
-# Outputs: Q
-SB_DFFNESR 17 0 4 1
-- - - -
-
-# Inputs: C D E R
-# Outputs: Q
-SB_DFFNER 18 0 4 1
-- - - -
-
-# Inputs: C D E S
-# Outputs: Q
-SB_DFFNESS 19 0 4 1
-- - - -
-
-# Inputs: C D E S
-# Outputs: Q
-SB_DFFNES 20 0 4 1
-- - - -
-
-# Inputs: CI I0 I1
+# Inputs: I0 I1 CI
 # Outputs: CO
-SB_CARRY 21 1 3 1
-126 259 231
+#   (NB: carry chain input/output must be last
+#        input/output and have been moved there
+#        overriding the alphabetical ordering)
+SB_CARRY 1 1 3 1
+259 231 126
 
 # Inputs: I0 I1 I2 I3
 # Outputs: O
-SB_LUT4 22 1 4 1
+SB_LUT4 2 1 4 1
 449 400 379 316
diff --git a/techlibs/ice40/abc_lp.box b/techlibs/ice40/abc_lp.box
index eb1cd0937..fbe4c56e6 100644
--- a/techlibs/ice40/abc_lp.box
+++ b/techlibs/ice40/abc_lp.box
@@ -1,113 +1,17 @@
 # From https://github.com/cliffordwolf/icestorm/blob/be0bca0/icefuzz/timings_lp8k.txt
 
 # NB: Inputs/Outputs must be ordered alphabetically
-
-# Inputs: C D
-# Outputs: Q
-SB_DFF 1 0 2 1
-- -
-
-# Inputs: C D E
-# Outputs: Q
-SB_DFFE 2 0 3 1
-- - -
-
-# Inputs: C D R
-# Outputs: Q
-SB_DFFSR 3 0 3 1
-- - -
-
-# Inputs: C D R
-# Outputs: Q
-SB_DFFR 4 0 3 1
-- - -
-
-# Inputs: C D S
-# Outputs: Q
-SB_DFFSS 5 0 3 1
-- - -
-
-# Inputs: C D S
-# Outputs: Q
-SB_DFFS 6 0 3 1
-- - -
-
-# Inputs: C D E R
-# Outputs: Q
-SB_DFFESR 7 0 4 1
-- - - -
-
-# Inputs: C D E R
-# Outputs: Q
-SB_DFFER 8 0 4 1
-- - - -
-
-# Inputs: C D E S
-# Outputs: Q
-SB_DFFESS 9 0 4 1
-- - - -
-
-# Inputs: C D E S
-# Outputs: Q
-SB_DFFES 10 0 4 1
-- - - -
-
-# Inputs: C D
-# Outputs: Q
-SB_DFFN 11 0 2 1
-- -
-
-# Inputs: C D E
-# Outputs: Q
-SB_DFFNE 12 0 3 1
-- - -
-
-# Inputs: C D R
-# Outputs: Q
-SB_DFFNSR 13 0 3 1
-- - -
-
-# Inputs: C D R
-# Outputs: Q
-SB_DFFNR 14 0 3 1
-- - -
-
-# Inputs: C D S
-# Outputs: Q
-SB_DFFNSS 15 0 3 1
-- - -
-
-# Inputs: C D S
-# Outputs: Q
-SB_DFFNS 16 0 3 1
-- - -
-
-# Inputs: C D E R
-# Outputs: Q
-SB_DFFNESR 17 0 4 1
-- - - -
-
-# Inputs: C D E R
-# Outputs: Q
-SB_DFFNER 18 0 4 1
-- - - -
-
-# Inputs: C D E S
-# Outputs: Q
-SB_DFFNESS 19 0 4 1
-- - - -
-
-# Inputs: C D E S
-# Outputs: Q
-SB_DFFNES 20 0 4 1
-- - - -
+#     (with exceptions for carry in/out)
 
 # Inputs: CI I0 I1
 # Outputs: CO
-SB_CARRY 21 1 3 1
-186 675 609
+#   (NB: carry chain input/output must be last
+#        input/output and have been moved there
+#        overriding the alphabetical ordering)
+SB_CARRY 1 1 3 1
+675 609 186 
 
 # Inputs: I0 I1 I2 I3
 # Outputs: O
-SB_LUT4 22 1 4 1
+SB_LUT4 2 1 4 1
 661 589 558 465
diff --git a/techlibs/ice40/abc_u.box b/techlibs/ice40/abc_u.box
index 3b5834e40..f44deabc4 100644
--- a/techlibs/ice40/abc_u.box
+++ b/techlibs/ice40/abc_u.box
@@ -1,113 +1,17 @@
 # From https://github.com/cliffordwolf/icestorm/blob/be0bca0/icefuzz/timings_up5k.txt
 
 # NB: Inputs/Outputs must be ordered alphabetically
+#     (with exceptions for carry in/out)
 
-# Inputs: C D
-# Outputs: Q
-SB_DFF 1 0 2 1
-- -
-
-# Inputs: C D E
-# Outputs: Q
-SB_DFFE 2 0 3 1
-- - -
-
-# Inputs: C D R
-# Outputs: Q
-SB_DFFSR 3 0 3 1
-- - -
-
-# Inputs: C D R
-# Outputs: Q
-SB_DFFR 4 0 3 1
-- - -
-
-# Inputs: C D S
-# Outputs: Q
-SB_DFFSS 5 0 3 1
-- - -
-
-# Inputs: C D S
-# Outputs: Q
-SB_DFFS 6 0 3 1
-- - -
-
-# Inputs: C D E R
-# Outputs: Q
-SB_DFFESR 7 0 4 1
-- - - -
-
-# Inputs: C D E R
-# Outputs: Q
-SB_DFFER 8 0 4 1
-- - - -
-
-# Inputs: C D E S
-# Outputs: Q
-SB_DFFESS 9 0 4 1
-- - - -
-
-# Inputs: C D E S
-# Outputs: Q
-SB_DFFES 10 0 4 1
-- - - -
-
-# Inputs: C D
-# Outputs: Q
-SB_DFFN 11 0 2 1
-- -
-
-# Inputs: C D E
-# Outputs: Q
-SB_DFFNE 12 0 3 1
-- - -
-
-# Inputs: C D R
-# Outputs: Q
-SB_DFFNSR 13 0 3 1
-- - -
-
-# Inputs: C D R
-# Outputs: Q
-SB_DFFNR 14 0 3 1
-- - -
-
-# Inputs: C D S
-# Outputs: Q
-SB_DFFNSS 15 0 3 1
-- - -
-
-# Inputs: C D S
-# Outputs: Q
-SB_DFFNS 16 0 3 1
-- - -
-
-# Inputs: C D E R
-# Outputs: Q
-SB_DFFNESR 17 0 4 1
-- - - -
-
-# Inputs: C D E R
-# Outputs: Q
-SB_DFFNER 18 0 4 1
-- - - -
-
-# Inputs: C D E S
-# Outputs: Q
-SB_DFFNESS 19 0 4 1
-- - - -
-
-# Inputs: C D E S
-# Outputs: Q
-SB_DFFNES 20 0 4 1
-- - - -
-
-# Inputs: CI I0 I1
+# Inputs: I0 I1 CI
 # Outputs: CO
-SB_CARRY 21 1 3 1
-278 675 609
+#   (NB: carry chain input/output must be last
+#        input/output and have been moved there
+#        overriding the alphabetical ordering)
+SB_CARRY 1 1 3 1
+675 609 278
 
 # Inputs: I0 I1 I2 I3
 # Outputs: O
-SB_LUT4 22 1 4 1
+SB_LUT4 2 1 4 1
 1285 1231 1205 874
diff --git a/techlibs/ice40/cells_sim.v b/techlibs/ice40/cells_sim.v
index 031afa85c..b746ba4e5 100644
--- a/techlibs/ice40/cells_sim.v
+++ b/techlibs/ice40/cells_sim.v
@@ -127,7 +127,7 @@ endmodule
 
 // SiliconBlue Logic Cells
 
-(* abc_box_id = 22, lib_whitebox *)
+(* abc_box_id = 2, lib_whitebox *)
 module SB_LUT4 (output O, input I0, I1, I2, I3);
 	parameter [15:0] LUT_INIT = 0;
 	wire [7:0] s3 = I3 ? LUT_INIT[15:8] : LUT_INIT[7:0];
@@ -136,20 +136,16 @@ module SB_LUT4 (output O, input I0, I1, I2, I3);
 	assign O = I0 ? s1[1] : s1[0];
 endmodule
 
-(* abc_box_id = 21, abc_carry, lib_whitebox *)
-module SB_CARRY ((* abc_carry_out *) output CO, input I0, I1, (* abc_carry_in *) input CI);
+(* abc_box_id = 1, abc_carry="CI,CO", lib_whitebox *)
+module SB_CARRY (output CO, input I0, I1, CI);
 	assign CO = (I0 && I1) || ((I0 || I1) && CI);
 endmodule
 
 // Positive Edge SiliconBlue FF Cells
 
 module SB_DFF (output `SB_DFF_REG, input C, D);
-`ifndef _ABC
 	always @(posedge C)
 		Q <= D;
-`else
-    always @* Q <= D;
-`endif
 endmodule
 
 module SB_DFFE (output `SB_DFF_REG, input C, E, D);
@@ -896,7 +892,6 @@ module SB_WARMBOOT (
 );
 endmodule
 
-(* nomem2reg *)
 module SB_SPRAM256KA (
 	input [13:0] ADDRESS,
 	input [15:0] DATAIN,
diff --git a/techlibs/ice40/ice40_unlut.cc b/techlibs/ice40/ice40_unlut.cc
index 2428a8e78..d16e6e6a3 100644
--- a/techlibs/ice40/ice40_unlut.cc
+++ b/techlibs/ice40/ice40_unlut.cc
@@ -74,7 +74,7 @@ static void run_ice40_unlut(Module *module)
 }
 
 struct Ice40UnlutPass : public Pass {
-	Ice40UnlutPass() : Pass("ice40_unlut", "iCE40: perform simple optimizations") { }
+	Ice40UnlutPass() : Pass("ice40_unlut", "iCE40: transform SB_LUT4 cells to $lut cells") { }
 	void help() YS_OVERRIDE
 	{
 		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
diff --git a/techlibs/ice40/synth_ice40.cc b/techlibs/ice40/synth_ice40.cc
index d8e9786c5..9dd5d81f7 100644
--- a/techlibs/ice40/synth_ice40.cc
+++ b/techlibs/ice40/synth_ice40.cc
@@ -38,8 +38,8 @@ struct SynthIce40Pass : public ScriptPass
 		log("This command runs synthesis for iCE40 FPGAs.\n");
 		log("\n");
 		log("    -device < hx | lp | u >\n");
-		log("        optimise the synthesis netlist for the specified device.\n");
-		log("        HX is the default target if no device argument specified.\n");
+		log("        relevant only for '-abc9' flow, optimise timing for the specified device.\n");
+		log("        default: hx\n");
 		log("\n");
 		log("    -top <module>\n");
 		log("        use the specified module as top module\n");
@@ -105,7 +105,6 @@ struct SynthIce40Pass : public ScriptPass
 		log("\n");
 	}
 
-
 	string top_opt, blif_file, edif_file, json_file, abc, device_opt;
 	bool nocarry, nodffe, nobram, dsp, flatten, retime, relut, noabc, abc2, vpr;
 	int min_ce_use;
@@ -331,8 +330,16 @@ struct SynthIce40Pass : public ScriptPass
 				run("techmap -map +/gate2lut.v -D LUT_WIDTH=4", "(only if -noabc)");
 			}
 			if (!noabc) {
-				if (abc == "abc9")
-					run(abc + stringf(" -lut +/ice40/abc_%s.lut -box +/ice40/abc_%s.box", device_opt.c_str(), device_opt.c_str()), "(skip if -noabc)");
+				if (abc == "abc9") {
+					int wire_delay;
+					if (device_opt == "lp")
+						wire_delay = 400;
+					else if (device_opt == "u")
+						wire_delay = 750;
+					else
+						wire_delay = 250;
+					run(abc + stringf(" -W %d -lut +/ice40/abc_%s.lut -box +/ice40/abc_%s.box", wire_delay, device_opt.c_str(), device_opt.c_str()), "(skip if -noabc)");
+				}
 				else
 					run(abc + " -dress -lut 4", "(skip if -noabc)");
 			}
diff --git a/techlibs/xilinx/Makefile.inc b/techlibs/xilinx/Makefile.inc
index 12ec20053..860fcd88c 100644
--- a/techlibs/xilinx/Makefile.inc
+++ b/techlibs/xilinx/Makefile.inc
@@ -30,9 +30,11 @@ $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/drams_map.v))
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/arith_map.v))
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/ff_map.v))
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/lut_map.v))
+
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/abc_ff.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))
 
 $(eval $(call add_gen_share_file,share/xilinx,techlibs/xilinx/brams_init_36.vh))
 $(eval $(call add_gen_share_file,share/xilinx,techlibs/xilinx/brams_init_32.vh))
diff --git a/techlibs/xilinx/abc_xc7.box b/techlibs/xilinx/abc_xc7.box
index 4caf69320..bb9258e78 100644
--- a/techlibs/xilinx/abc_xc7.box
+++ b/techlibs/xilinx/abc_xc7.box
@@ -1,5 +1,8 @@
 # Max delays from https://github.com/SymbiFlow/prjxray-db/blob/34ea6eb08a63d21ec16264ad37a0a7b142ff6031/artix7/timings/CLBLL_L.sdf
 
+# NB: Inputs/Outputs must be ordered alphabetically
+#     (with exceptions for carry in/out)
+
 # F7BMUX slower than F7AMUX
 # Inputs: I0 I1 S0
 # Outputs: O
@@ -12,34 +15,42 @@ MUXF8 2 1 3 1
 104 94 273
 
 # CARRY4 + CARRY4_[ABCD]X
-# Inputs: S0 S1 S2 S3 CYINIT DI0 DI1 DI2 DI3 CI
+# Inputs: CYINIT DI0 DI1 DI2 DI3 S0 S1 S2 S3 CI
 # Outputs:  O0 O1 O2 O3 CO0 CO1 CO2 CO3
-#   (NB: carry chain input/output must be last input/output,
-#        swapped with what normally would have been the last
-#        output, here: CI <-> S, CO <-> O
+#   (NB: carry chain input/output must be last
+#        input/output and the entire bus has been
+#        moved there overriding the otherwise
+#        alphabetical ordering)
 CARRY4 3 1 10 8
-223 -   -   -   482 -   -   -   -   222
-400 205 -   -   598 407 -   -   -   334
-523 558 226 -   584 556 537 -   -   239
-582 618 330 227 642 615 596 438 -   313
-340 -   -   -   536 379 -   -   -   271
-433 469 -   -   494 465 445 -   -   157
-512 548 292 -   592 540 520 356 -   228
-508 528 378 380 580 526 507 398 385 114
+482 -   -   -   -   223 -   -   -   222
+598 407 -   -   -   400 205 -   -   334
+584 556 537 -   -   523 558 226 -   239
+642 615 596 438 -   582 618 330 227 313
+536 379 -   -   -   340 -   -   -   271
+494 465 445 -   -   433 469 -   -   157
+592 540 520 356 -   512 548 292 -   228
+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 4 0 13 2
+-   -   -   -   -   - 631 472 407 238 127 - -
+631 472 407 238 127 - -   -   -   -   -   - -
 
 # SLICEM/A6LUT
 # Inputs: A0 A1 A2 A3 A4 A5 D DPRA0 DPRA1 DPRA2 DPRA3 DPRA4 DPRA5 WCLK WE
 # Outputs: DPO SPO
-RAM64X1D 4 0 15 2
--   -   -   -   -   -   - 124 124 124 124 124 124 - -
-124 124 124 124 124 124 - -   -   -   -   -   124 - -
+RAM64X1D 5 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 5 0 17 2
--   -   -   -   -   -   -   - 314 314 314 314 314 314 292 - -
-347 347 347 347 347 347 296 - -   -   -   -   -   -   -   - -
+RAM128X1D 6 0 17 2
+-    -    -   -   -   -   -   - 1009 998 839 774 605 494 450 - -
+1047 1036 877 812 643 532 478 - -    -   -   -   -   -   -   - -
 
 # Inputs: C CE D R \$pastQ
 # Outputs: Q
diff --git a/techlibs/xilinx/abc_xc7.lut b/techlibs/xilinx/abc_xc7.lut
index f69a923d0..bcbdec127 100644
--- a/techlibs/xilinx/abc_xc7.lut
+++ b/techlibs/xilinx/abc_xc7.lut
@@ -8,7 +8,7 @@
 4	3	127 238 407 472
 5	3	127 238 407 472 631
 6	5	127 238 407 472 631 642
-		# F7AMUX.S+F7BMUX.S + AOUTMUX+COUTMUX / 2
+		# (F7[AB]MUX.S + [AC]OUTMUX) / 2
 7	10	464 513 624 793 858 1017 1028
 		# F8MUX.S+BOUTMUX
 		    # F8MUX.I0+F7MUX.S+BOUTMUX
diff --git a/techlibs/xilinx/abc_xc7_nowide.lut b/techlibs/xilinx/abc_xc7_nowide.lut
new file mode 100644
index 000000000..fab48c879
--- /dev/null
+++ b/techlibs/xilinx/abc_xc7_nowide.lut
@@ -0,0 +1,10 @@
+# Max delays from https://github.com/SymbiFlow/prjxray-db/blob/82bf5f158cd8e9a11ac4d04f1aeef48ed1a528a5/artix7/timings/CLBLL_L.sdf
+#            and  https://github.com/SymbiFlow/prjxray-db/blob/82bf5f158cd8e9a11ac4d04f1aeef48ed1a528a5/artix7/tile_type_CLBLL_L.json
+
+# K	area	delay
+1 	1	127
+2	2	127 238
+3	3	127 238 407
+4	3	127 238 407 472
+5	3	127 238 407 472 631
+6	5	127 238 407 472 631 642
diff --git a/techlibs/xilinx/cells_map.v b/techlibs/xilinx/cells_map.v
index b5114758c..9a316fc96 100644
--- a/techlibs/xilinx/cells_map.v
+++ b/techlibs/xilinx/cells_map.v
@@ -20,16 +20,14 @@
 
 // Convert negative-polarity reset to positive-polarity
 (* techmap_celltype = "$_DFF_NN0_" *)
-module _90_dff_nn0_to_np0(input D, C, R, output Q); \$_DFF_NP0_  _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .R(~R)); endmodule
+module _90_dff_nn0_to_np0 (input D, C, R, output Q); \$_DFF_NP0_  _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .R(~R)); endmodule
 (* techmap_celltype = "$_DFF_PN0_" *)
-module _90_dff_pn0_to_pp0(input D, C, R, output Q); \$_DFF_PP0_  _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .R(~R)); endmodule
-
+module _90_dff_pn0_to_pp0 (input D, C, R, output Q); \$_DFF_PP0_  _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .R(~R)); endmodule
 (* techmap_celltype = "$_DFF_NN1_" *)
 module _90_dff_nn1_to_np1 (input D, C, R, output Q); \$_DFF_NP1   _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .R(~R)); endmodule
 (* techmap_celltype = "$_DFF_PN1_" *)
 module _90_dff_pn1_to_pp1 (input D, C, R, output Q); \$_DFF_PP1   _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .R(~R)); endmodule
 
-
 module \$__SHREG_ (input C, input D, input E, output Q);
   parameter DEPTH = 0;
   parameter [DEPTH-1:0] INIT = 0;
diff --git a/techlibs/xilinx/cells_sim.v b/techlibs/xilinx/cells_sim.v
index bf7a0ed44..5a148be01 100644
--- a/techlibs/xilinx/cells_sim.v
+++ b/techlibs/xilinx/cells_sim.v
@@ -173,8 +173,8 @@ module XORCY(output O, input CI, LI);
   assign O = CI ^ LI;
 endmodule
 
-(* abc_box_id = 3, abc_carry, lib_whitebox *)
-module CARRY4((* abc_carry_out *) output [3:0] CO, output [3:0] O, (* abc_carry_in *) input CI, input CYINIT, input [3:0] DI, S);
+(* abc_box_id = 3, abc_carry="CI,CO", lib_whitebox *)
+module CARRY4(output [3:0] CO, O, input CI, CYINIT, input [3:0] DI, S);
   assign O = S ^ {CO[2:0], CI | CYINIT};
   assign CO[0] = S[0] ? CI | CYINIT : DI[0];
   assign CO[1] = S[1] ? CO[0] : DI[1];
@@ -281,7 +281,25 @@ module FDPE_1 (output reg Q, input C, CE, D, PRE);
   always @(negedge C, posedge PRE) if (PRE) Q <= 1'b1; else if (CE) Q <= D;
 endmodule
 
-//(* abc_box_id = 4 /*, lib_whitebox*/ *)
+(* abc_box_id = 4, abc_scc_break="D,WE" *)
+module RAM32X1D (
+  output DPO, SPO,
+  input  D, WCLK, WE,
+  input  A0, A1, A2, A3, A4,
+  input  DPRA0, DPRA1, DPRA2, DPRA3, DPRA4
+);
+  parameter INIT = 32'h0;
+  parameter IS_WCLK_INVERTED = 1'b0;
+  wire [4:0] a = {A4, A3, A2, A1, A0};
+  wire [4:0] dpra = {DPRA4, DPRA3, DPRA2, DPRA1, DPRA0};
+  reg [31:0] mem = INIT;
+  assign SPO = mem[a];
+  assign DPO = mem[dpra];
+  wire clk = WCLK ^ IS_WCLK_INVERTED;
+  always @(posedge clk) if (WE) mem[a] <= D;
+endmodule
+
+(* abc_box_id = 5, abc_scc_break="D,WE" *)
 module RAM64X1D (
   output DPO, SPO,
   input  D, WCLK, WE,
@@ -299,7 +317,7 @@ module RAM64X1D (
   always @(posedge clk) if (WE) mem[a] <= D;
 endmodule
 
-//(* abc_box_id = 5 /*, lib_whitebox*/ *)
+(* abc_box_id = 6, abc_scc_break="D,WE" *)
 module RAM128X1D (
   output       DPO, SPO,
   input        D, WCLK, WE,
diff --git a/techlibs/xilinx/cells_xtra.sh b/techlibs/xilinx/cells_xtra.sh
index 2b384f405..53b528820 100644
--- a/techlibs/xilinx/cells_xtra.sh
+++ b/techlibs/xilinx/cells_xtra.sh
@@ -120,7 +120,7 @@ function xtract_cell_decl()
 	xtract_cell_decl RAM128X1S
 	xtract_cell_decl RAM256X1S
 	xtract_cell_decl RAM32M
-	xtract_cell_decl RAM32X1D
+	#xtract_cell_decl RAM32X1D
 	xtract_cell_decl RAM32X1S
 	xtract_cell_decl RAM32X1S_1
 	xtract_cell_decl RAM32X2S
diff --git a/techlibs/xilinx/cells_xtra.v b/techlibs/xilinx/cells_xtra.v
index 0ec3d0df0..15fa1b63a 100644
--- a/techlibs/xilinx/cells_xtra.v
+++ b/techlibs/xilinx/cells_xtra.v
@@ -3694,13 +3694,6 @@ module RAM32M (...);
     input WE;
 endmodule
 
-module RAM32X1D (...);
-    parameter [31:0] INIT = 32'h00000000;
-    parameter [0:0] IS_WCLK_INVERTED = 1'b0;
-    output DPO, SPO;
-    input A0, A1, A2, A3, A4, D, DPRA0, DPRA1, DPRA2, DPRA3, DPRA4, WCLK, WE;
-endmodule
-
 module RAM32X1S (...);
     parameter [31:0] INIT = 32'h00000000;
     parameter [0:0] IS_WCLK_INVERTED = 1'b0;
diff --git a/techlibs/xilinx/drams.txt b/techlibs/xilinx/drams.txt
index 91632bcee..2613c206c 100644
--- a/techlibs/xilinx/drams.txt
+++ b/techlibs/xilinx/drams.txt
@@ -1,4 +1,17 @@
 
+bram $__XILINX_RAM32X1D
+  init 1
+  abits 5
+  dbits 1
+  groups 2
+  ports  1 1
+  wrmode 0 1
+  enable 0 1
+  transp 0 0
+  clocks 0 1
+  clkpol 0 2
+endbram
+
 bram $__XILINX_RAM64X1D
   init 1
   abits 6
@@ -25,6 +38,13 @@ bram $__XILINX_RAM128X1D
   clkpol 0 2
 endbram
 
+match $__XILINX_RAM32X1D
+  min bits 3
+  min wports 1
+  make_outreg
+  or_next_if_better
+endmatch
+
 match $__XILINX_RAM64X1D
   min bits 5
   min wports 1
diff --git a/techlibs/xilinx/drams_map.v b/techlibs/xilinx/drams_map.v
index 47476b592..77041ca86 100644
--- a/techlibs/xilinx/drams_map.v
+++ b/techlibs/xilinx/drams_map.v
@@ -1,4 +1,38 @@
 
+module \$__XILINX_RAM32X1D (CLK1, A1ADDR, A1DATA, B1ADDR, B1DATA, B1EN);
+	parameter [31:0] INIT = 32'bx;
+	parameter CLKPOL2 = 1;
+	input CLK1;
+
+	input [4:0] A1ADDR;
+	output A1DATA;
+
+	input [4:0] B1ADDR;
+	input B1DATA;
+	input B1EN;
+
+	RAM32X1D #(
+		.INIT(INIT),
+		.IS_WCLK_INVERTED(!CLKPOL2)
+	) _TECHMAP_REPLACE_ (
+		.DPRA0(A1ADDR[0]),
+		.DPRA1(A1ADDR[1]),
+		.DPRA2(A1ADDR[2]),
+		.DPRA3(A1ADDR[3]),
+		.DPRA4(A1ADDR[4]),
+		.DPO(A1DATA),
+
+		.A0(B1ADDR[0]),
+		.A1(B1ADDR[1]),
+		.A2(B1ADDR[2]),
+		.A3(B1ADDR[3]),
+		.A4(B1ADDR[4]),
+		.D(B1DATA),
+		.WCLK(CLK1),
+		.WE(B1EN)
+	);
+endmodule
+
 module \$__XILINX_RAM64X1D (CLK1, A1ADDR, A1DATA, B1ADDR, B1DATA, B1EN);
 	parameter [63:0] INIT = 64'bx;
 	parameter CLKPOL2 = 1;
diff --git a/techlibs/xilinx/lut_map.v b/techlibs/xilinx/lut_map.v
index d07c59dee..13d3c3268 100644
--- a/techlibs/xilinx/lut_map.v
+++ b/techlibs/xilinx/lut_map.v
@@ -29,61 +29,86 @@ module \$lut (A, Y);
   input [WIDTH-1:0] A;
   output Y;
 
+  // Need to swap input ordering, and fix init accordingly,
+  // to match ABC's expectation of LUT inputs in non-decreasing
+  // delay order
+  function [WIDTH-1:0] permute_index;
+      input [WIDTH-1:0] i;
+      integer j;
+      begin
+          permute_index = 0;
+          for (j = 0; j < WIDTH; j = j + 1)
+              permute_index[WIDTH-1 - j] = i[j];
+      end
+  endfunction
+
+  function [2**WIDTH-1:0] permute_init;
+      input [2**WIDTH-1:0] orig;
+      integer i;
+      begin
+          permute_init = 0;
+          for (i = 0; i < 2**WIDTH; i = i + 1)
+              permute_init[i] = orig[permute_index(i)];
+      end
+  endfunction
+
+  parameter [2**WIDTH-1:0] P_LUT = permute_init(LUT);
+
   generate
     if (WIDTH == 1) begin
-      LUT1 #(.INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
+      LUT1 #(.INIT(P_LUT)) _TECHMAP_REPLACE_ (.O(Y),
         .I0(A[0]));
     end else
     if (WIDTH == 2) begin
-      LUT2 #(.INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(A[1]));
+      LUT2 #(.INIT(P_LUT)) _TECHMAP_REPLACE_ (.O(Y),
+        .I0(A[1]), .I1(A[0]));
     end else
     if (WIDTH == 3) begin
-      LUT3 #(.INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]));
+      LUT3 #(.INIT(P_LUT)) _TECHMAP_REPLACE_ (.O(Y),
+        .I0(A[2]), .I1(A[1]), .I2(A[0]));
     end else
     if (WIDTH == 4) begin
-      LUT4 #(.INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]));
+      LUT4 #(.INIT(P_LUT)) _TECHMAP_REPLACE_ (.O(Y),
+        .I0(A[3]), .I1(A[2]), .I2(A[1]),
+        .I3(A[0]));
     end else
     if (WIDTH == 5) begin
-      LUT5 #(.INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]));
+      LUT5 #(.INIT(P_LUT)) _TECHMAP_REPLACE_ (.O(Y),
+        .I0(A[4]), .I1(A[3]), .I2(A[2]),
+        .I3(A[1]), .I4(A[0]));
     end else
     if (WIDTH == 6) begin
-      LUT6 #(.INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]), .I5(A[5]));
+      LUT6 #(.INIT(P_LUT)) _TECHMAP_REPLACE_ (.O(Y),
+        .I0(A[5]), .I1(A[4]), .I2(A[3]),
+        .I3(A[2]), .I4(A[1]), .I5(A[0]));
     end else
     if (WIDTH == 7) begin
       wire T0, T1;
-      LUT6 #(.INIT(LUT[63:0])) fpga_lut_0 (.O(T0),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]), .I5(A[5]));
-      LUT6 #(.INIT(LUT[127:64])) fpga_lut_1 (.O(T1),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]), .I5(A[5]));
-      MUXF7 fpga_mux_0 (.O(Y), .I0(T0), .I1(T1), .S(A[6]));
+      LUT6 #(.INIT(P_LUT[63:0])) fpga_lut_0 (.O(T0),
+        .I0(A[6]), .I1(A[5]), .I2(A[4]),
+        .I3(A[3]), .I4(A[2]), .I5(A[1]));
+      LUT6 #(.INIT(P_LUT[127:64])) fpga_lut_1 (.O(T1),
+        .I0(A[6]), .I1(A[5]), .I2(A[4]),
+        .I3(A[3]), .I4(A[2]), .I5(A[1]));
+      MUXF7 fpga_mux_0 (.O(Y), .I0(T0), .I1(T1), .S(A[0]));
     end else
     if (WIDTH == 8) begin
       wire T0, T1, T2, T3, T4, T5;
-      LUT6 #(.INIT(LUT[63:0])) fpga_lut_0 (.O(T0),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]), .I5(A[5]));
-      LUT6 #(.INIT(LUT[127:64])) fpga_lut_1 (.O(T1),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]), .I5(A[5]));
-      LUT6 #(.INIT(LUT[191:128])) fpga_lut_2 (.O(T2),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]), .I5(A[5]));
-      LUT6 #(.INIT(LUT[255:192])) fpga_lut_3 (.O(T3),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]),
-        .I3(A[3]), .I4(A[4]), .I5(A[5]));
-      MUXF7 fpga_mux_0 (.O(T4), .I0(T0), .I1(T1), .S(A[6]));
-      MUXF7 fpga_mux_1 (.O(T5), .I0(T2), .I1(T3), .S(A[6]));
-      MUXF8 fpga_mux_2 (.O(Y), .I0(T4), .I1(T5), .S(A[7]));
+      LUT6 #(.INIT(P_LUT[63:0])) fpga_lut_0 (.O(T0),
+        .I0(A[7]), .I1(A[6]), .I2(A[5]),
+        .I3(A[4]), .I4(A[3]), .I5(A[2]));
+      LUT6 #(.INIT(P_LUT[127:64])) fpga_lut_1 (.O(T1),
+        .I0(A[7]), .I1(A[6]), .I2(A[5]),
+        .I3(A[4]), .I4(A[3]), .I5(A[2]));
+      LUT6 #(.INIT(P_LUT[191:128])) fpga_lut_2 (.O(T2),
+        .I0(A[7]), .I1(A[6]), .I2(A[5]),
+        .I3(A[4]), .I4(A[3]), .I5(A[2]));
+      LUT6 #(.INIT(P_LUT[255:192])) fpga_lut_3 (.O(T3),
+        .I0(A[7]), .I1(A[6]), .I2(A[5]),
+        .I3(A[4]), .I4(A[3]), .I5(A[2]));
+      MUXF7 fpga_mux_0 (.O(T4), .I0(T0), .I1(T1), .S(A[1]));
+      MUXF7 fpga_mux_1 (.O(T5), .I0(T2), .I1(T3), .S(A[1]));
+      MUXF8 fpga_mux_2 (.O(Y), .I0(T4), .I1(T5), .S(A[0]));
     end else begin
       wire _TECHMAP_FAIL_ = 1;
     end
diff --git a/techlibs/xilinx/synth_xilinx.cc b/techlibs/xilinx/synth_xilinx.cc
index d3f096220..cdc64db1d 100644
--- a/techlibs/xilinx/synth_xilinx.cc
+++ b/techlibs/xilinx/synth_xilinx.cc
@@ -45,8 +45,9 @@ struct SynthXilinxPass : public ScriptPass
 		log("    -top <module>\n");
 		log("        use the specified module as top module\n");
 		log("\n");
-		log("    -arch {xcup|xcu|xc7|xc6s}\n");
+		log("    -family {xcup|xcu|xc7|xc6s}\n");
 		log("        run synthesis for the specified Xilinx architecture\n");
+		log("        generate the synthesis netlist for the specified family.\n");
 		log("        default: xc7\n");
 		log("\n");
 		log("    -edif <file>\n");
@@ -61,9 +62,6 @@ struct SynthXilinxPass : public ScriptPass
 		log("        generate an output netlist (and BLIF file) suitable for VPR\n");
 		log("        (this feature is experimental and incomplete)\n");
 		log("\n");
-		log("    -nocarry\n");
-		log("        disable inference of carry chains\n");
-		log("\n");
 		log("    -nobram\n");
 		log("        disable inference of block rams\n");
 		log("\n");
@@ -73,6 +71,12 @@ struct SynthXilinxPass : public ScriptPass
 		log("    -nosrl\n");
 		log("        disable inference of shift registers\n");
 		log("\n");
+		log("    -nocarry\n");
+		log("        do not use XORCY/MUXCY/CARRY4 cells in output netlist\n");
+		log("\n");
+		log("    -nowidelut\n");
+		log("        do not use MUXF[78] resources to implement LUTs larger than LUT6s\n");
+		log("\n");
 		log("    -run <from_label>:<to_label>\n");
 		log("        only run the commands between the labels (see below). an empty\n");
 		log("        from label is synonymous to 'begin', and empty to label is\n");
@@ -93,15 +97,15 @@ struct SynthXilinxPass : public ScriptPass
 		log("\n");
 	}
 
-	std::string top_opt, edif_file, blif_file, abc, arch;
-	bool flatten, retime, vpr, nocarry, nobram, nodram, nosrl;
+	std::string top_opt, edif_file, blif_file, family;
+	bool flatten, retime, vpr, nobram, nodram, nosrl, nocarry, nowidelut, abc9;
 
 	void clear_flags() YS_OVERRIDE
 	{
 		top_opt = "-auto-top";
 		edif_file.clear();
 		blif_file.clear();
-		abc = "abc";
+		family = "xc7";
 		flatten = false;
 		retime = false;
 		vpr = false;
@@ -109,7 +113,9 @@ struct SynthXilinxPass : public ScriptPass
 		nobram = false;
 		nodram = false;
 		nosrl = false;
-		arch = "xc7";
+		nocarry = false;
+		nowidelut = false;
+		abc9 = false;
 	}
 
 	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
@@ -124,8 +130,8 @@ struct SynthXilinxPass : public ScriptPass
 				top_opt = "-top " + args[++argidx];
 				continue;
 			}
-			if (args[argidx] == "-arch" && argidx+1 < args.size()) {
-				arch = args[++argidx];
+			if ((args[argidx] == "-family" || args[argidx] == "-arch") && argidx+1 < args.size()) {
+				family = args[++argidx];
 				continue;
 			}
 			if (args[argidx] == "-edif" && argidx+1 < args.size()) {
@@ -152,6 +158,14 @@ struct SynthXilinxPass : public ScriptPass
 				retime = true;
 				continue;
 			}
+			if (args[argidx] == "-nocarry") {
+				nocarry = true;
+				continue;
+			}
+			if (args[argidx] == "-nowidelut") {
+				nowidelut = true;
+				continue;
+			}
 			if (args[argidx] == "-vpr") {
 				vpr = true;
 				continue;
@@ -173,15 +187,15 @@ struct SynthXilinxPass : public ScriptPass
 				continue;
 			}
 			if (args[argidx] == "-abc9") {
-				abc = "abc9";
+				abc9 = true;
 				continue;
 			}
 			break;
 		}
 		extra_args(args, argidx, design);
 
-		if (arch != "xcup" && arch != "xcu" && arch != "xc7" && arch != "xc6s")
-			log_cmd_error("Invalid Xilinx -arch setting: %s\n", arch.c_str());
+		if (family != "xcup" && family != "xcu" && family != "xc7" && family != "xc6s")
+			log_cmd_error("Invalid Xilinx -family setting: %s\n", family.c_str());
 
 		if (!design->full_selection())
 			log_cmd_error("This command only operates on fully selected designs!\n");
@@ -225,11 +239,6 @@ struct SynthXilinxPass : public ScriptPass
 			//   so attempt to convert $pmux-es to the former
 			if (!nosrl || help_mode)
 				run("pmux2shiftx", "(skip if '-nosrl')");
-
-			// Run a number of peephole optimisations, including one
-			//   that optimises $mul cells driving $shiftx's B input
-			//   and that aids wide mux analysis
-			run("peepopt");
 		}
 
 		if (check_label("bram", "(skip if '-nobram')")) {
@@ -268,7 +277,7 @@ struct SynthXilinxPass : public ScriptPass
 				techmap_files += " -map +/xilinx/arith_map.v";
 				if (vpr)
 					techmap_files += " -D _EXPLICIT_CARRY";
-				else if (abc == "abc9")
+				else if (abc9)
 					techmap_files += " -D _CLB_CARRY";
 			}
 			run("techmap " + techmap_files);
@@ -276,7 +285,7 @@ struct SynthXilinxPass : public ScriptPass
 		}
 
 		if (check_label("map_cells")) {
-			if (abc == "abc9")
+			if (abc9)
 				run("techmap -map +/techmap.v -map +/xilinx/cells_map.v -D _ABC -map +/xilinx/ff_map.v");
 			else
 				run("techmap -map +/techmap.v -map +/xilinx/cells_map.v");
@@ -284,21 +293,31 @@ struct SynthXilinxPass : public ScriptPass
 		}
 
 		if (check_label("map_luts")) {
-			if (abc == "abc9") {
+			run("opt_expr -mux_undef");
+			if (help_mode)
+				run("abc -luts 2:2,3,6:5[,10,20] [-dff]", "(skip if 'nowidelut', only for '-retime')");
+			else if (abc9) {
+				if (family != "xc7")
+					log_warning("'synth_xilinx -abc9' currently supports '-family xc7' only.\n");
 				run("read_verilog -icells -lib +/xilinx/abc_ff.v");
-				run(abc + " -lut +/xilinx/abc_xc7.lut -box +/xilinx/abc_xc7.box -W " + XC7_WIRE_DELAY + string(retime ? " -retime" : ""));
+				if (nowidelut)
+					run("abc9 -lut +/xilinx/abc_xc7_nowide.lut -box +/xilinx/abc_xc7.box -W " + std::string(XC7_WIRE_DELAY) + string(retime ? " -dff" : ""));
+				else
+					run("abc9 -lut +/xilinx/abc_xc7.lut -box +/xilinx/abc_xc7.box -W " + std::string(XC7_WIRE_DELAY) + string(retime ? " -dff" : ""));
+			}
+			else {
+				if (nowidelut)
+					run("abc -luts 2:2,3,6:5" + string(retime ? " -dff" : ""));
+				else
+					run("abc -luts 2:2,3,6:5,10,20" + string(retime ? " -dff" : ""));
 			}
-			else if (help_mode)
-				run(abc + " -luts 2:2,3,6:5,10,20 [-dff]");
-			else
-				run(abc + " -luts 2:2,3,6:5,10,20" + string(retime ? " -dff" : ""));
 			run("clean");
 
 			// This shregmap call infers fixed length shift registers after abc
 			//   has performed any necessary retiming
 			if (!nosrl || help_mode)
 				run("shregmap -minlen 3 -init -params -enpol any_or_none", "(skip if '-nosrl')");
-			if (abc == "abc9")
+			if (abc9)
 				run("techmap -map +/xilinx/lut_map.v -map +/xilinx/cells_map.v");
 			else
 				run("techmap -map +/xilinx/lut_map.v -map +/xilinx/cells_map.v -map +/xilinx/ff_map.v");
diff --git a/tests/aiger/.gitignore b/tests/aiger/.gitignore
index 073f46157..9a26bb8f4 100644
--- a/tests/aiger/.gitignore
+++ b/tests/aiger/.gitignore
@@ -1,2 +1 @@
-*.log
-*.out
+/*_ref.v
diff --git a/tests/aiger/run-test.sh b/tests/aiger/run-test.sh
index f52eb4ac1..deaf48a3d 100755
--- a/tests/aiger/run-test.sh
+++ b/tests/aiger/run-test.sh
@@ -2,6 +2,16 @@
 
 set -e
 
+OPTIND=1
+abcprog="../../yosys-abc"    # default to built-in version of abc
+while getopts "A:" opt
+do
+    case "$opt" in
+	A) abcprog="$OPTARG" ;;
+    esac
+done
+shift "$((OPTIND-1))"
+
 # NB: *.aag and *.aig must contain a symbol table naming the primary
 #     inputs and outputs, otherwise ABC and Yosys will name them
 #     arbitrarily (and inconsistently with each other).
@@ -10,8 +20,9 @@ for aag in *.aag; do
     # Since ABC cannot read *.aag, read the *.aig instead
     # (which would have been created by the reference aig2aig utility,
     #  available from http://fmv.jku.at/aiger/)
-    ../../yosys-abc -c "read -c ${aag%.*}.aig; write ${aag%.*}_ref.v"
-    ../../yosys -p "
+    echo "Checking $aag."
+    $abcprog -q "read -c ${aag%.*}.aig; write ${aag%.*}_ref.v"
+    ../../yosys -qp "
 read_verilog ${aag%.*}_ref.v
 prep
 design -stash gold
@@ -26,8 +37,9 @@ sat -verify -prove-asserts -show-ports -seq 16 miter
 done
 
 for aig in *.aig; do
-    ../../yosys-abc -c "read -c $aig; write ${aig%.*}_ref.v"
-    ../../yosys -p "
+    echo "Checking $aig."
+    $abcprog -q "read -c $aig; write ${aig%.*}_ref.v"
+    ../../yosys -qp "
 read_verilog ${aig%.*}_ref.v
 prep
 design -stash gold
diff --git a/tests/arch/run-test.sh b/tests/arch/run-test.sh
new file mode 100755
index 000000000..5292d1615
--- /dev/null
+++ b/tests/arch/run-test.sh
@@ -0,0 +1,18 @@
+#!/bin/bash
+
+set -e
+
+echo "Running syntax check on arch sim models"
+for arch in ../../techlibs/*; do
+	find $arch -name cells_sim.v | while read path; do
+		echo -n "Test $path ->"
+		iverilog -t null -I$arch $path
+		echo " ok"
+	done
+done
+
+for path in "../../techlibs/common/simcells.v"  "../../techlibs/common/simlib.v"; do
+	echo -n "Test $path ->"
+	iverilog -t null $path
+	echo " ok"
+done
diff --git a/tests/memories/issue00335.v b/tests/memories/issue00335.v
new file mode 100644
index 000000000..f3b6e5dfe
--- /dev/null
+++ b/tests/memories/issue00335.v
@@ -0,0 +1,28 @@
+// expect-wr-ports 1
+// expect-rd-ports 1
+// expect-rd-clk \clk
+
+module ram2 (input clk,
+             input             sel,
+             input             we, 
+             input [SIZE-1:0]  adr, 
+             input [63:0]      dat_i, 
+             output reg [63:0] dat_o);
+   parameter  SIZE = 5; // Address size
+
+   reg [63:0] mem [0:(1 << SIZE)-1];
+   integer    i;
+
+   initial begin
+      for (i = 0; i < (1<<SIZE) - 1; i = i + 1)
+        mem[i] <= 0;
+   end
+   
+   always @(posedge clk)
+     if (sel) begin
+       if (~we)
+         dat_o <= mem[adr];
+       else
+         mem[adr] <= dat_i;
+     end
+endmodule
diff --git a/tests/memories/issue00710.v b/tests/memories/issue00710.v
new file mode 100644
index 000000000..7a5fad1c2
--- /dev/null
+++ b/tests/memories/issue00710.v
@@ -0,0 +1,17 @@
+// expect-wr-ports 1
+// expect-rd-ports 1
+// expect-rd-clk \clk
+
+module top(input clk, input we, re, reset, input [7:0] addr, wdata, output reg [7:0] rdata);
+
+reg [7:0] bram[0:255];
+(* keep *) reg dummy;
+
+always @(posedge clk)
+	if (reset)
+		dummy <= 1'b0;
+	else if (re)
+		rdata <= bram[addr];
+	else if (we)
+		bram[addr] <= wdata;
+endmodule
diff --git a/tests/memories/run-test.sh b/tests/memories/run-test.sh
index 734a96682..76acaa9cd 100755
--- a/tests/memories/run-test.sh
+++ b/tests/memories/run-test.sh
@@ -4,17 +4,19 @@ set -e
 
 OPTIND=1
 seed=""    # default to no seed specified
-while getopts "S:" opt
+abcopt=""
+while getopts "A:S:" opt
 do
     case "$opt" in
+	A) abcopt="-A $OPTARG" ;;
 	S) seed="-S $OPTARG" ;;
     esac
 done
 shift "$((OPTIND-1))"
 
-bash ../tools/autotest.sh $seed -G *.v
+bash ../tools/autotest.sh $abcopt $seed -G *.v
 
-for f in `egrep -l 'expect-(wr|rd)-ports' *.v`; do
+for f in `egrep -l 'expect-(wr-ports|rd-ports|rd-clk)' *.v`; do
 	echo -n "Testing expectations for $f .."
 	../../yosys -qp "proc; opt; memory -nomap;; dump -outfile ${f%.v}.dmp t:\$mem" $f
 	if grep -q expect-wr-ports $f; then
@@ -25,6 +27,10 @@ for f in `egrep -l 'expect-(wr|rd)-ports' *.v`; do
 		grep -q "parameter \\\\RD_PORTS $(gawk '/expect-rd-ports/ { print $3; }' $f)\$" ${f%.v}.dmp ||
 				{ echo " ERROR: Unexpected number of read ports."; false; }
 	fi
+	if grep -q expect-rd-clk $f; then
+		grep -q "connect \\\\RD_CLK \\$(gawk '/expect-rd-clk/ { print $3; }' $f)\$" ${f%.v}.dmp ||
+				{ echo " ERROR: Unexpected read clock."; false; }
+	fi
 	echo " ok."
 done
 
diff --git a/tests/opt/opt_ff_sat.v b/tests/opt/opt_ff_sat.v
new file mode 100644
index 000000000..5a0a6fe37
--- /dev/null
+++ b/tests/opt/opt_ff_sat.v
@@ -0,0 +1,12 @@
+module top (
+	input clk,
+	output reg [7:0] cnt
+);
+	initial cnt = 0;
+	always @(posedge clk) begin
+		if (cnt < 20)
+			cnt <= cnt + 1;
+		else
+			cnt <= 0;
+	end
+endmodule
diff --git a/tests/opt/opt_ff_sat.ys b/tests/opt/opt_ff_sat.ys
new file mode 100644
index 000000000..4e7cc6ca4
--- /dev/null
+++ b/tests/opt/opt_ff_sat.ys
@@ -0,0 +1,5 @@
+read_verilog opt_ff_sat.v
+prep -flatten
+opt_rmdff -sat
+synth
+select -assert-count 5 t:$_DFF_P_
diff --git a/tests/simple/arrays02.sv b/tests/simple/arrays02.sv
new file mode 100644
index 000000000..76c2a7388
--- /dev/null
+++ b/tests/simple/arrays02.sv
@@ -0,0 +1,16 @@
+module uut_arrays02(clock, we, addr, wr_data, rd_data);
+
+input clock, we;
+input [3:0] addr, wr_data;
+output [3:0] rd_data;
+reg [3:0] rd_data;
+
+reg [3:0] memory [16];
+
+always @(posedge clock) begin
+	if (we)
+		memory[addr] <= wr_data;
+	rd_data <= memory[addr];
+end
+
+endmodule
diff --git a/tests/simple/defvalue.sv b/tests/simple/defvalue.sv
new file mode 100644
index 000000000..b0a087ecb
--- /dev/null
+++ b/tests/simple/defvalue.sv
@@ -0,0 +1,22 @@
+module top(input clock, input [3:0] delta, output [3:0] cnt1, cnt2);
+	cnt #(1) foo (.clock, .cnt(cnt1), .delta);
+	cnt #(2) bar (.clock, .cnt(cnt2));
+endmodule
+
+module cnt #(
+	parameter integer initval = 0
+) (
+	input clock,
+	output logic [3:0] cnt = initval,
+`ifdef __ICARUS__
+	input [3:0] delta
+`else
+	input [3:0] delta = 10
+`endif
+);
+`ifdef __ICARUS__
+	assign (weak0, weak1) delta = 10;
+`endif
+	always @(posedge clock)
+		cnt <= cnt + delta;
+endmodule
diff --git a/tests/simple/generate.v b/tests/simple/generate.v
index 3c55682cb..0e353ad9b 100644
--- a/tests/simple/generate.v
+++ b/tests/simple/generate.v
@@ -148,3 +148,14 @@ generate
 endgenerate
 assign out = steps[WIDTH].outer[0].val;
 endmodule
+
+// ------------------------------------------
+
+module gen_test6(output [3:0] o);
+generate
+    genvar i;
+    for (i = 3; i >= 0; i = i-1) begin
+        assign o[i] = 1'b0;
+    end
+endgenerate
+endmodule
diff --git a/tests/simple_abc9/abc9.v b/tests/simple_abc9/abc9.v
index 0b83c34a3..64b625efe 100644
--- a/tests/simple_abc9/abc9.v
+++ b/tests/simple_abc9/abc9.v
@@ -262,3 +262,8 @@ endmodule
 module abc9_test025(input [3:0] i, output [3:0] o);
 abc9_test024_sub a(i[2:1], o[2:1]);
 endmodule
+
+module abc9_test026(output [3:0] o, p);
+assign o = { 1'b1, 1'bx };
+assign p = { 1'b1, 1'bx, 1'b0 };
+endmodule
diff --git a/tests/tools/autotest.sh b/tests/tools/autotest.sh
index 23964a751..4d3478628 100755
--- a/tests/tools/autotest.sh
+++ b/tests/tools/autotest.sh
@@ -23,12 +23,13 @@ warn_iverilog_git=false
 # The tests are skipped if firrtl2verilog is the empty string (the default).
 firrtl2verilog=""
 xfirrtl="../xfirrtl"
+abcprog="$toolsdir/../../yosys-abc"
 
 if [ ! -f $toolsdir/cmp_tbdata -o $toolsdir/cmp_tbdata.c -nt $toolsdir/cmp_tbdata ]; then
 	( set -ex; ${CC:-gcc} -Wall -o $toolsdir/cmp_tbdata $toolsdir/cmp_tbdata.c; ) || exit 1
 fi
 
-while getopts xmGl:wkjvref:s:p:n:S:I:-: opt; do
+while getopts xmGl:wkjvref:s:p:n:S:I:A:-: opt; do
 	case "$opt" in
 		x)
 			use_xsim=true ;;
@@ -65,6 +66,8 @@ while getopts xmGl:wkjvref:s:p:n:S:I:-: opt; do
 			include_opts="$include_opts -I $OPTARG"
 			xinclude_opts="$xinclude_opts -i $OPTARG"
 			minclude_opts="$minclude_opts +incdir+$OPTARG" ;;
+		A)
+			abcprog="$OPTARG" ;;
 		-)
 			case "${OPTARG}" in
 			    xfirrtl)
@@ -89,8 +92,7 @@ done
 
 compile_and_run() {
 	exe="$1"; output="$2"; shift 2
-	ext=${1##*.}
-	if [ "$ext" == "sv" ]; then
+	if [ "${2##*.}" == "sv" ]; then
 		language_gen="-g2012"
 	else
 		language_gen="-g2005"
@@ -142,23 +144,25 @@ do
 		cd ${bn}.out
 		fn=$(basename $fn)
 		bn=$(basename $bn)
+		refext=v
 
 		rm -f ${bn}_ref.fir
 		if [[ "$ext" == "v" ]]; then
 			egrep -v '^\s*`timescale' ../$fn > ${bn}_ref.${ext}
 		elif [[ "$ext" == "aig" ]] || [[ "$ext" == "aag" ]]; then
-			"$toolsdir"/../../yosys-abc -c "read_aiger ../${fn}; write ${bn}_ref.v"
+			$abcprog -c "read_aiger ../${fn}; write ${bn}_ref.${refext}"
 		else
-			cp ../${fn} ${bn}_ref.${ext}
+			refext=$ext
+			cp ../${fn} ${bn}_ref.${refext}
 		fi
 
 		if [ ! -f ../${bn}_tb.v ]; then
-			"$toolsdir"/../../yosys -f "$frontend $include_opts" -b "test_autotb $autotb_opts" -o ${bn}_tb.v ${bn}_ref.v
+			"$toolsdir"/../../yosys -f "$frontend $include_opts -D_AUTOTB" -b "test_autotb $autotb_opts" -o ${bn}_tb.v ${bn}_ref.${refext}
 		else
 			cp ../${bn}_tb.v ${bn}_tb.v
 		fi
 		if $genvcd; then sed -i 's,// \$dump,$dump,g' ${bn}_tb.v; fi
-		compile_and_run ${bn}_tb_ref ${bn}_out_ref ${bn}_tb.v ${bn}_ref.v $libs \
+		compile_and_run ${bn}_tb_ref ${bn}_out_ref ${bn}_tb.v ${bn}_ref.${refext} $libs \
 					"$toolsdir"/../../techlibs/common/simlib.v \
 					"$toolsdir"/../../techlibs/common/simcells.v
 		if $genvcd; then mv testbench.vcd ${bn}_ref.vcd; fi
@@ -175,25 +179,25 @@ do
 			test_count=$(( test_count + 1 ))
 		}
 
-		if [ "$frontend" = "verific" -o "$frontend" = "verific_gates" ] && grep -q VERIFIC-SKIP ${bn}_ref.v; then
+		if [ "$frontend" = "verific" -o "$frontend" = "verific_gates" ] && grep -q VERIFIC-SKIP ${bn}_ref.${refext}; then
 			touch ../${bn}.skip
 			return
 		fi
 
 		if [ -n "$scriptfiles" ]; then
-			test_passes -f "$frontend $include_opts" ${bn}_ref.v $scriptfiles
+			test_passes -f "$frontend $include_opts" ${bn}_ref.${refext} $scriptfiles
 		elif [ -n "$scriptopt" ]; then
-			test_passes -f "$frontend $include_opts" -p "$scriptopt" ${bn}_ref.v
+			test_passes -f "$frontend $include_opts" -p "$scriptopt" ${bn}_ref.${refext}
 		elif [ "$frontend" = "verific" ]; then
-			test_passes -p "verific -vlog2k ${bn}_ref.v; verific -import -all; opt; memory;;"
+			test_passes -p "verific -vlog2k ${bn}_ref.${refext}; verific -import -all; opt; memory;;"
 		elif [ "$frontend" = "verific_gates" ]; then
-			test_passes -p "verific -vlog2k ${bn}_ref.v; verific -import -gates -all; opt; memory;;"
+			test_passes -p "verific -vlog2k ${bn}_ref.${refext}; verific -import -gates -all; opt; memory;;"
 		else
-			test_passes -f "$frontend $include_opts" -p "hierarchy; proc; opt; memory; opt; fsm; opt -full -fine" ${bn}_ref.v
-			test_passes -f "$frontend $include_opts" -p "hierarchy; synth -run coarse; techmap; opt; abc -dff" ${bn}_ref.v
+			test_passes -f "$frontend $include_opts" -p "hierarchy; proc; opt; memory; opt; fsm; opt -full -fine" ${bn}_ref.${refext}
+			test_passes -f "$frontend $include_opts" -p "hierarchy; synth -run coarse; techmap; opt; abc -dff" ${bn}_ref.${refext}
 			if [ -n "$firrtl2verilog" ]; then
 			    if test -z "$xfirrtl" || ! grep "$fn" "$xfirrtl" ; then
-				"$toolsdir"/../../yosys -b "firrtl" -o ${bn}_ref.fir -f "$frontend $include_opts" -p "prep -nordff; proc; opt; memory; opt; fsm; opt -full -fine; pmuxtree" ${bn}_ref.v
+				"$toolsdir"/../../yosys -b "firrtl" -o ${bn}_ref.fir -f "$frontend $include_opts" -p "prep -nordff; proc; opt; memory; opt; fsm; opt -full -fine; pmuxtree" ${bn}_ref.${refext}
 				$firrtl2verilog -i ${bn}_ref.fir -o ${bn}_ref.fir.v
 				test_passes -f "$frontend $include_opts" -p "hierarchy; proc; opt; memory; opt; fsm; opt -full -fine" ${bn}_ref.fir.v
 			    fi
diff --git a/tests/various/.gitignore b/tests/various/.gitignore
index 397b4a762..7b3e8c68e 100644
--- a/tests/various/.gitignore
+++ b/tests/various/.gitignore
@@ -1 +1,2 @@
-*.log
+/*.log
+/*.out
diff --git a/tests/various/abc9.v b/tests/various/abc9.v
new file mode 100644
index 000000000..8271cd249
--- /dev/null
+++ b/tests/various/abc9.v
@@ -0,0 +1,5 @@
+module abc9_test027(output reg o);
+initial o = 1'b0;
+always @*
+    o <= ~o;
+endmodule
diff --git a/tests/various/abc9.ys b/tests/various/abc9.ys
new file mode 100644
index 000000000..922f7005d
--- /dev/null
+++ b/tests/various/abc9.ys
@@ -0,0 +1,14 @@
+read_verilog abc9.v
+proc
+design -save gold
+
+abc9 -lut 4
+check
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
diff --git a/tests/various/muxcover.ys b/tests/various/muxcover.ys
index 7ac460f13..67e9625e6 100644
--- a/tests/various/muxcover.ys
+++ b/tests/various/muxcover.ys
@@ -13,7 +13,7 @@ read_verilog -formal <<EOT
 EOT
 
 
-## Examle usage for "pmuxtree" and "muxcover"
+## Example usage for "pmuxtree" and "muxcover"
 
 proc
 pmuxtree
@@ -49,3 +49,462 @@ hierarchy -top equiv
 equiv_simple -undef
 equiv_status -assert
 
+## Partial matching MUX4
+
+design -reset
+read_verilog -formal <<EOT
+module mux_if_bal_3_1 #(parameter N=3, parameter W=1) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @* begin
+    o <= {{W{{1'bx}}}};
+    if (s[0] == 1'b0)
+     if (s[1] == 1'b0)
+      o <= i[0*W+:W];
+     else
+      o <= i[1*W+:W];
+    else
+     if (s[1] == 1'b0)
+      o <= i[2*W+:W];
+end
+endmodule
+EOT
+prep
+design -save gold
+
+techmap
+muxcover -mux4=150
+select -assert-count 0 t:$_MUX_
+select -assert-count 1 t:$_MUX4_
+select -assert-count 0 t:$_MUX8_
+select -assert-count 0 t:$_MUX16_
+techmap -map +/simcells.v t:$_MUX4_
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+## Partial matching MUX8
+
+design -reset
+read_verilog -formal <<EOT
+module mux_if_bal_5_1 #(parameter N=5, parameter W=1) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @* begin
+    o <= {{W{{1'bx}}}};
+    if (s[0] == 1'b0)
+     if (s[1] == 1'b0)
+      if (s[2] == 1'b0)
+       o <= i[0*W+:W];
+      else
+       o <= i[1*W+:W];
+     else
+      if (s[2] == 1'b0)
+       o <= i[2*W+:W];
+      else
+       o <= i[3*W+:W];
+    else
+     if (s[1] == 1'b0)
+      if (s[2] == 1'b0)
+       o <= i[4*W+:W];
+end
+endmodule
+EOT
+prep
+design -save gold
+
+techmap
+muxcover -mux4=150 -mux8=200
+clean
+opt_expr -mux_bool
+select -assert-count 0 t:$_MUX_
+select -assert-count 0 t:$_MUX4_
+select -assert-count 1 t:$_MUX8_
+select -assert-count 0 t:$_MUX16_
+techmap -map +/simcells.v t:$_MUX8_
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+## Partial matching MUX16
+
+design -reset
+read_verilog -formal <<EOT
+module mux_if_bal_9_1 #(parameter N=9, parameter W=1) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @* begin
+    o <= {{W{{1'bx}}}};
+    if (s[0] == 1'b0)
+     if (s[1] == 1'b0)
+      if (s[2] == 1'b0)
+       if (s[3] == 1'b0)
+        o <= i[0*W+:W];
+       else
+        o <= i[1*W+:W];
+      else
+       if (s[3] == 1'b0)
+        o <= i[2*W+:W];
+       else
+        o <= i[3*W+:W];
+     else
+      if (s[2] == 1'b0)
+       if (s[3] == 1'b0)
+        o <= i[4*W+:W];
+       else
+        o <= i[5*W+:W];
+      else
+       if (s[3] == 1'b0)
+        o <= i[6*W+:W];
+       else
+        o <= i[7*W+:W];
+    else
+     if (s[1] == 1'b0)
+      if (s[2] == 1'b0)
+       if (s[3] == 1'b0)
+        o <= i[8*W+:W];
+end
+endmodule
+EOT
+prep
+design -save gold
+
+techmap
+muxcover -mux4=150 -mux8=200 -mux16=250
+clean
+opt_expr -mux_bool
+select -assert-count 0 t:$_MUX_
+select -assert-count 0 t:$_MUX4_
+select -assert-count 0 t:$_MUX8_
+select -assert-count 1 t:$_MUX16_
+techmap -map +/simcells.v t:$_MUX16_
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+## MUX2 in MUX4 :: https://github.com/YosysHQ/yosys/issues/1132
+
+design -reset
+read_verilog -formal <<EOT
+module mux2in4(input [1:0] i, input s, output o);
+    assign o = s ? i[1] : i[0];
+endmodule
+EOT
+prep
+design -save gold
+
+techmap
+muxcover -mux4=99 -nodecode
+clean
+opt_expr -mux_bool
+select -assert-count 0 t:$_MUX_
+select -assert-count 1 t:$_MUX4_
+select -assert-count 0 t:$_MUX8_
+select -assert-count 0 t:$_MUX16_
+techmap -map +/simcells.v t:$_MUX4_
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+## MUX2 in MUX8 :: https://github.com/YosysHQ/yosys/issues/1132
+
+design -reset
+read_verilog -formal <<EOT
+module mux2in8(input [1:0] i, input s, output o);
+    assign o = s ? i[1] : i[0];
+endmodule
+EOT
+prep
+design -save gold
+
+techmap
+muxcover -mux8=99 -nodecode
+clean
+opt_expr -mux_bool
+select -assert-count 0 t:$_MUX_
+select -assert-count 0 t:$_MUX4_
+select -assert-count 1 t:$_MUX8_
+select -assert-count 0 t:$_MUX16_
+techmap -map +/simcells.v t:$_MUX8_
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+## MUX4 in MUX8 :: https://github.com/YosysHQ/yosys/issues/1132
+
+design -reset
+read_verilog -formal <<EOT
+module mux4in8(input [3:0] i, input [1:0] s, output o);
+    assign o = s[1] ? (s[0] ? i[3] : i[2]) : (s[0] ? i[1] : i[0]);
+endmodule
+EOT
+prep
+design -save gold
+
+techmap
+muxcover -mux8=299 -nodecode
+clean
+opt_expr -mux_bool
+select -assert-count 0 t:$_MUX_
+select -assert-count 0 t:$_MUX4_
+select -assert-count 1 t:$_MUX8_
+select -assert-count 0 t:$_MUX16_
+techmap -map +/simcells.v t:$_MUX8_
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+## MUX2 in MUX16 :: https://github.com/YosysHQ/yosys/issues/1132
+
+design -reset
+read_verilog -formal <<EOT
+module mux2in16(input [1:0] i, input s, output o);
+    assign o = s ? i[1] : i[0];
+endmodule
+EOT
+prep
+design -save gold
+
+techmap
+muxcover -mux16=99 -nodecode
+clean
+opt_expr -mux_bool
+select -assert-count 0 t:$_MUX_
+select -assert-count 0 t:$_MUX4_
+select -assert-count 0 t:$_MUX8_
+select -assert-count 1 t:$_MUX16_
+techmap -map +/simcells.v t:$_MUX16_
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+## MUX4 in MUX16 :: https://github.com/YosysHQ/yosys/issues/1132
+
+design -reset
+read_verilog -formal <<EOT
+module mux4in16(input [3:0] i, input [1:0] s, output o);
+    assign o = s[1] ? (s[0] ? i[3] : i[2]) : (s[0] ? i[1] : i[0]);
+endmodule
+EOT
+prep
+design -save gold
+
+techmap
+muxcover -mux16=299 -nodecode
+clean
+opt_expr -mux_bool
+select -assert-count 0 t:$_MUX_
+select -assert-count 0 t:$_MUX4_
+select -assert-count 0 t:$_MUX8_
+select -assert-count 1 t:$_MUX16_
+techmap -map +/simcells.v t:$_MUX16_
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+## MUX8 in MUX16 :: https://github.com/YosysHQ/yosys/issues/1132
+
+design -reset
+read_verilog -formal <<EOT
+module mux4in16(input [7:0] i, input [2:0] s, output o);
+    assign o = s[2] ? s[1] ? (s[0] ? i[3] : i[2]) : (s[0] ? i[1] : i[0])
+                    : s[1] ? (s[0] ? i[7] : i[6]) : (s[0] ? i[5] : i[4]);
+endmodule
+EOT
+prep
+design -save gold
+
+techmap
+muxcover -mux16=699 -nodecode
+clean
+opt_expr -mux_bool
+select -assert-count 0 t:$_MUX_
+select -assert-count 0 t:$_MUX4_
+select -assert-count 0 t:$_MUX8_
+select -assert-count 1 t:$_MUX16_
+techmap -map +/simcells.v t:$_MUX16_
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+## mux_if_bal_5_1 :: https://github.com/YosysHQ/yosys/issues/1132
+
+design -reset
+read_verilog -formal <<EOT
+module mux_if_bal_5_1 #(parameter N=5, parameter W=1) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @* begin
+    o <= {{W{{1'bx}}}};
+    if (s[0] == 1'b0)
+     if (s[1] == 1'b0)
+      if (s[2] == 1'b0)
+       o <= i[0*W+:W];
+      else
+       o <= i[1*W+:W];
+     else
+      if (s[2] == 1'b0)
+       o <= i[2*W+:W];
+      else
+       o <= i[3*W+:W];
+    else
+     if (s[1] == 1'b0)
+      if (s[2] == 1'b0)
+       o <= i[4*W+:W];
+end
+endmodule
+EOT
+prep
+design -save gold
+
+wreduce
+opt -full
+techmap
+muxcover -mux8=350
+clean
+opt_expr -mux_bool
+select -assert-count 0 t:$_MUX_
+select -assert-count 0 t:$_MUX4_
+select -assert-count 1 t:$_MUX8_
+select -assert-count 0 t:$_MUX16_
+techmap -map +/simcells.v t:$_MUX8_
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs -ignore_gold_x gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+## mux_if_bal_5_1 (nodecode) :: https://github.com/YosysHQ/yosys/issues/1132
+design -load gold
+
+wreduce
+opt -full
+techmap
+muxcover -mux8=350 -nodecode
+clean
+opt_expr -mux_bool
+select -assert-count 0 t:$_MUX_
+select -assert-count 0 t:$_MUX4_
+select -assert-count 1 t:$_MUX8_
+select -assert-count 0 t:$_MUX16_
+techmap -map +/simcells.v t:$_MUX8_
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs -ignore_gold_x gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+## mux_if_bal_9_1 :: https://github.com/YosysHQ/yosys/issues/1132
+
+design -reset
+read_verilog -formal <<EOT
+module mux_if_bal_9_1 #(parameter N=9, parameter W=1) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @* begin
+    o <= {{W{{1'bx}}}};
+    if (s[3] == 1'b0)
+     if (s[2] == 1'b0)
+      if (s[1] == 1'b0)
+       if (s[0] == 1'b0)
+        o <= i[0*W+:W];
+       else
+        o <= i[1*W+:W];
+      else
+       if (s[0] == 1'b0)
+        o <= i[2*W+:W];
+       else
+        o <= i[3*W+:W];
+     else
+      if (s[1] == 1'b0)
+       if (s[0] == 1'b0)
+        o <= i[4*W+:W];
+       else
+        o <= i[5*W+:W];
+      else
+       if (s[0] == 1'b0)
+        o <= i[6*W+:W];
+       else
+        o <= i[7*W+:W];
+    else
+     if (s[2] == 1'b0)
+      if (s[1] == 1'b0)
+       if (s[0] == 1'b0)
+        o <= i[8*W+:W];
+end
+endmodule
+EOT
+prep
+design -save gold
+
+wreduce
+opt -full
+techmap
+muxcover -mux16=750
+clean
+opt_expr -mux_bool
+select -assert-count 0 t:$_MUX_
+select -assert-count 0 t:$_MUX4_
+select -assert-count 0 t:$_MUX8_
+select -assert-count 1 t:$_MUX16_
+techmap -map +/simcells.v t:$_MUX16_
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs -ignore_gold_x gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+## mux_if_bal_9_1 (nodecode) :: https://github.com/YosysHQ/yosys/issues/1132
+
+design -load gold
+
+wreduce
+opt -full
+techmap
+muxcover -mux16=750 -nodecode
+clean
+opt_expr -mux_bool
+select -assert-count 0 t:$_MUX_
+select -assert-count 0 t:$_MUX4_
+select -assert-count 0 t:$_MUX8_
+select -assert-count 1 t:$_MUX16_
+techmap -map +/simcells.v t:$_MUX16_
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+
+miter -equiv -flatten -make_assert -make_outputs -ignore_gold_x gold gate miter
+sat -verify -prove-asserts -show-ports miter
diff --git a/tests/various/muxpack.v b/tests/various/muxpack.v
new file mode 100644
index 000000000..33ece1f16
--- /dev/null
+++ b/tests/various/muxpack.v
@@ -0,0 +1,259 @@
+module mux_if_unbal_4_1 #(parameter N=4, parameter W=1) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @*
+    if (s == 0) o <= i[0*W+:W];
+    else if (s == 1) o <= i[1*W+:W];
+    else if (s == 2) o <= i[2*W+:W];
+    else if (s == 3) o <= i[3*W+:W];
+    else o <= {W{1'bx}};
+endmodule
+
+module mux_if_unbal_5_3 #(parameter N=5, parameter W=3) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @* begin
+    o <= {W{1'bx}};
+    if (s == 0) o <= i[0*W+:W];
+    if (s == 1) o <= i[1*W+:W];
+    if (s == 2) o <= i[2*W+:W];
+    if (s == 3) o <= i[3*W+:W];
+    if (s == 4) o <= i[4*W+:W];
+end
+endmodule
+
+module mux_if_unbal_5_3_invert #(parameter N=5, parameter W=3) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @*
+    if (s != 0) 
+	   	if (s != 1) 
+			if (s != 2)
+				if (s != 3)
+					if (s != 4) o <= i[4*W+:W];
+					else o <= i[0*W+:W];
+				else o <= i[3*W+:W];
+			else o <= i[2*W+:W];
+		else o <= i[1*W+:W];
+    else o <= {W{1'bx}};
+endmodule
+
+module mux_if_unbal_5_3_width_mismatch #(parameter N=5, parameter W=3) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @* begin
+    o <= {W{1'bx}};
+    if (s == 0) o <= i[0*W+:W];
+    if (s == 1) o <= i[1*W+:W];
+    if (s == 2) o[W-2:0] <= i[2*W+:W-1];
+    if (s == 3) o <= i[3*W+:W];
+    if (s == 4) o <= i[4*W+:W];
+end
+endmodule
+
+module mux_if_unbal_4_1_missing #(parameter N=5, parameter W=3) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @* begin
+    if (s == 0) o <= i[0*W+:W];
+//    else if (s == 1) o <= i[1*W+:W];
+//    else if (s == 2) o <= i[2*W+:W];
+    else if (s == 3) o <= i[3*W+:W];
+    else o <= {W{1'bx}};
+end
+endmodule
+
+module mux_if_unbal_5_3_order #(parameter N=5, parameter W=3) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @* begin
+    o <= {W{1'bx}};
+    if (s == 3) o <= i[3*W+:W];
+    if (s == 2) o <= i[2*W+:W];
+    if (s == 1) o <= i[1*W+:W];
+    if (s == 4) o <= i[4*W+:W];
+    if (s == 0) o <= i[0*W+:W];
+end
+endmodule
+
+module mux_if_unbal_4_1_nonexcl #(parameter N=4, parameter W=1) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @*
+    if (s == 0) o <= i[0*W+:W];
+    else if (s == 1) o <= i[1*W+:W];
+    else if (s == 2) o <= i[2*W+:W];
+    else if (s == 3) o <= i[3*W+:W];
+	else if (s == 0) o <= {W{1'b0}};
+    else o <= {W{1'bx}};
+endmodule
+
+module mux_if_unbal_5_3_nonexcl #(parameter N=5, parameter W=3) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @* begin
+    o <= {W{1'bx}};
+    if (s == 0) o <= i[0*W+:W];
+    if (s == 1) o <= i[1*W+:W];
+    if (s == 2) o <= i[2*W+:W];
+    if (s == 3) o <= i[3*W+:W];
+    if (s == 4) o <= i[4*W+:W];
+	if (s == 0) o <= i[2*W+:W];
+end
+endmodule
+
+module mux_case_unbal_8_7#(parameter N=8, parameter W=7) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @* begin
+    o <= {W{1'bx}};
+    case (s)
+    0: o <= i[0*W+:W];
+    default:
+        case (s)
+        1: o <= i[1*W+:W];
+        2: o <= i[2*W+:W];
+        default:
+            case (s)
+            3: o <= i[3*W+:W];
+            4: o <= i[4*W+:W];
+            5: o <= i[5*W+:W];
+            default:
+                case (s)
+                    6: o <= i[6*W+:W];
+                    default: o <= i[7*W+:W];
+                endcase
+            endcase
+        endcase
+    endcase
+end
+endmodule
+
+module mux_if_bal_8_2 #(parameter N=8, parameter W=2) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @*
+    if (s[0] == 1'b0)
+     if (s[1] == 1'b0)
+      if (s[2] == 1'b0)
+       o <= i[0*W+:W];
+      else
+       o <= i[1*W+:W];
+     else
+      if (s[2] == 1'b0)
+       o <= i[2*W+:W];
+      else
+       o <= i[3*W+:W];
+    else
+     if (s[1] == 1'b0)
+      if (s[2] == 1'b0)
+       o <= i[4*W+:W];
+      else
+       o <= i[5*W+:W];
+     else
+      if (s[2] == 1'b0)
+       o <= i[6*W+:W];
+      else
+       o <= i[7*W+:W];
+endmodule
+
+module mux_if_bal_5_1 #(parameter N=5, parameter W=1) (input [N*W-1:0] i, input [$clog2(N)-1:0] s, output reg [W-1:0] o);
+always @*
+    if (s[0] == 1'b0)
+     if (s[1] == 1'b0)
+      if (s[2] == 1'b0)
+       o <= i[0*W+:W];
+      else
+       o <= i[1*W+:W];
+     else
+      if (s[2] == 1'b0)
+       o <= i[2*W+:W];
+      else
+       o <= i[3*W+:W];
+    else
+     o <= i[4*W+:W];
+endmodule
+
+module cliffordwolf_nonexclusive_select (
+        input wire x, y, z,
+        input wire a, b, c, d,
+        output reg o
+);
+        always @* begin
+                o = a;
+                if (x) o = b;
+                if (y) o = c;
+                if (z) o = d;
+        end
+endmodule
+
+module cliffordwolf_freduce (
+        input wire [1:0] s,
+        input wire a, b, c, d,
+        output reg [3:0] o
+);
+        always @* begin
+                o = {4{a}};
+                if (s == 0) o = {3{b}};
+                if (s == 1) o = {2{c}};
+                if (s == 2) o = d;
+        end
+endmodule
+
+module case_nonexclusive_select (
+        input wire [1:0] x, y,
+        input wire a, b, c, d, e,
+        output reg o
+);
+        always @* begin
+            case (x)
+                0: o = b;
+                2: o = b;
+                1: o = c;
+                default: begin
+                    o = a;
+                    if (y == 0) o = d;
+                    if (y == 1) o = e;
+                end
+        endcase
+        end
+endmodule
+
+module case_nonoverlap (
+        input wire [2:0] x,
+        input wire a, b, c, d, e,
+        output reg o
+);
+        always @* begin
+            case (x)
+                0, 2: o = b; // Creates $reduce_or
+                1: o = c;
+                default:
+                    case (x)
+                        3: o = d; 4: o = d; // Creates $reduce_or
+                        5: o = e;
+                        default: o = 1'b0;
+                    endcase
+        endcase
+        end
+endmodule
+
+module case_overlap (
+        input wire [2:0] x,
+        input wire a, b, c, d, e,
+        output reg o
+);
+        always @* begin
+            case (x)
+                0, 2: o = b; // Creates $reduce_or
+                1: o = c;
+                default:
+                    case (x)
+                        0: o = 1'b1; // OVERLAP!
+                        3, 4: o = d; // Creates $reduce_or
+                        5: o = e;
+                        default: o = 1'b0;
+                    endcase
+        endcase
+        end
+endmodule
+
+module case_overlap2 (
+        input wire [2:0] x,
+        input wire a, b, c, d, e,
+        output reg o
+);
+        always @* begin
+            case (x)
+                0: o = b; 2: o = b; // Creates $reduce_or
+                1: o = c;
+                default:
+                    case (x)
+                        0: o = d; 2: o = d; // Creates $reduce_or
+                        3: o = d; 4: o = d; // Creates $reduce_or
+                        5: o = e;
+                        default: o = 1'b0;
+                    endcase
+        endcase
+        end
+endmodule
diff --git a/tests/various/muxpack.ys b/tests/various/muxpack.ys
new file mode 100644
index 000000000..af23fcec8
--- /dev/null
+++ b/tests/various/muxpack.ys
@@ -0,0 +1,268 @@
+read_verilog muxpack.v
+design -save read
+
+hierarchy -top mux_if_unbal_4_1
+prep
+design -save gold
+muxpack
+opt
+stat
+select -assert-count 0 t:$mux
+select -assert-count 1 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top mux_if_unbal_5_3
+prep
+design -save gold
+muxpack
+opt
+stat
+select -assert-count 0 t:$mux
+select -assert-count 1 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+# TODO: Currently ExclusiveDatabase only analyses $eq cells
+#design -load read
+#hierarchy -top mux_if_unbal_5_3_invert
+#prep
+#design -save gold
+#muxpack
+#opt
+#stat
+#select -assert-count 0 t:$mux
+#select -assert-count 1 t:$pmux
+#design -stash gate
+#design -import gold -as gold
+#design -import gate -as gate
+#miter -equiv -flatten -make_assert -make_outputs gold gate miter
+#sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top mux_if_unbal_5_3_width_mismatch
+prep
+design -save gold
+muxpack
+opt
+stat
+select -assert-count 0 t:$mux
+select -assert-count 2 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top mux_if_unbal_4_1_missing
+prep
+design -save gold
+muxpack
+opt
+stat
+select -assert-count 0 t:$mux
+select -assert-count 1 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top mux_if_unbal_5_3_order
+prep
+design -save gold
+muxpack
+opt
+stat
+select -assert-count 0 t:$mux
+select -assert-count 1 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top mux_if_unbal_4_1_nonexcl
+prep
+design -save gold
+muxpack
+opt
+stat
+select -assert-count 0 t:$mux
+select -assert-count 1 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top mux_if_unbal_5_3_nonexcl
+prep
+design -save gold
+muxpack
+opt
+stat
+select -assert-count 0 t:$mux
+select -assert-count 1 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top mux_case_unbal_8_7
+prep
+design -save gold
+muxpack
+opt
+stat
+select -assert-count 0 t:$mux
+select -assert-count 1 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top mux_if_bal_8_2
+prep
+design -save gold
+muxpack
+opt
+stat
+select -assert-count 7 t:$mux
+select -assert-count 0 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top mux_if_bal_5_1
+prep
+design -save gold
+muxpack
+opt
+stat
+select -assert-count 4 t:$mux
+select -assert-count 0 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top cliffordwolf_nonexclusive_select
+prep
+design -save gold
+muxpack
+opt
+stat
+select -assert-count 3 t:$mux
+select -assert-count 0 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+#design -load read
+#hierarchy -top cliffordwolf_freduce
+#prep
+#design -save gold
+#proc; opt; freduce; opt
+#show
+#muxpack
+#opt
+#stat
+#select -assert-count 0 t:$mux
+#select -assert-count 1 t:$pmux
+#design -stash gate
+#design -import gold -as gold
+#design -import gate -as gate
+#miter -equiv -flatten -make_assert -make_outputs gold gate miter
+#sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top case_nonexclusive_select
+prep
+design -save gold
+muxpack
+opt
+stat
+select -assert-count 0 t:$mux
+select -assert-count 2 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top case_nonoverlap
+#prep # Do not prep otherwise $pmux's overlapping entry will get removed
+proc
+design -save gold
+opt -fast -mux_undef
+select -assert-count 2 t:$pmux
+muxpack
+opt
+stat
+select -assert-count 0 t:$mux
+select -assert-count 1 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top case_overlap
+#prep # Do not prep otherwise $pmux's overlapping entry will get removed
+proc
+design -save gold
+opt -fast -mux_undef
+select -assert-count 2 t:$pmux
+muxpack
+opt
+stat
+select -assert-count 0 t:$mux
+select -assert-count 2 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
+
+design -load read
+hierarchy -top case_overlap2
+#prep # Do not prep otherwise $pmux's overlapping entry will get removed
+proc
+design -save gold
+opt -fast -mux_undef
+select -assert-count 2 t:$pmux
+muxpack
+opt
+stat
+select -assert-count 0 t:$mux
+select -assert-count 2 t:$pmux
+design -stash gate
+design -import gold -as gold
+design -import gate -as gate
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports miter
diff --git a/tests/various/pmux2shiftx.v b/tests/various/pmux2shiftx.v
index fec84187b..563394080 100644
--- a/tests/various/pmux2shiftx.v
+++ b/tests/various/pmux2shiftx.v
@@ -32,3 +32,13 @@ module pmux2shiftx_test (
 		endcase
 	end
 endmodule
+
+module issue01135(input [7:0] i, output o);
+always @*
+case (i[6:3])
+    4: o <= i[0];
+    3: o <= i[2];
+    7: o <= i[3];
+    default: o <= 1'b0;
+endcase
+endmodule
diff --git a/tests/various/pmux2shiftx.ys b/tests/various/pmux2shiftx.ys
index deb134083..51ee2f7be 100644
--- a/tests/various/pmux2shiftx.ys
+++ b/tests/various/pmux2shiftx.ys
@@ -1,4 +1,7 @@
 read_verilog pmux2shiftx.v
+design -save read
+
+hierarchy -top pmux2shiftx_test
 prep
 design -save gold
 
@@ -21,8 +24,16 @@ design -import gate -as gate
 miter -equiv -flatten -make_assert -make_outputs gold gate miter
 sat -verify -prove-asserts -show-ports miter
 
-design -load gold
-stat
-
-design -load gate
-stat
+#design -load gold
+#stat
+#
+#design -load gate
+#stat
+
+design -load read
+hierarchy -top issue01135
+proc
+pmux2shiftx -norange
+opt -full
+select -assert-count 0 t:$shift*
+select -assert-count 1 t:$pmux
diff --git a/tests/various/shregmap.v b/tests/various/shregmap.v
new file mode 100644
index 000000000..604c2c976
--- /dev/null
+++ b/tests/various/shregmap.v
@@ -0,0 +1,48 @@
+module shregmap_static_test(input i, clk, output [1:0] q);
+reg head = 1'b0;
+reg [3:0] shift1 = 4'b0000;
+reg [3:0] shift2 = 4'b0000;
+
+always @(posedge clk) begin
+    head <= i;
+    shift1 <= {shift1[2:0], head};
+    shift2 <= {shift2[2:0], head};
+end
+
+assign q = {shift2[3], shift1[3]};
+endmodule
+
+module $__SHREG_DFF_P_(input C, D, output Q);
+parameter DEPTH = 1;
+parameter [DEPTH-1:0] INIT = {DEPTH{1'b0}};
+reg [DEPTH-1:0] r = INIT;
+always @(posedge C) 
+    r <= { r[DEPTH-2:0], D };
+assign Q = r[DEPTH-1];
+endmodule
+
+module shregmap_variable_test(input i, clk, input [1:0] l1, l2, output [1:0] q);
+reg head = 1'b0;
+reg [3:0] shift1 = 4'b0000;
+reg [3:0] shift2 = 4'b0000;
+
+always @(posedge clk) begin
+    head <= i;
+    shift1 <= {shift1[2:0], head};
+    shift2 <= {shift2[2:0], head};
+end
+
+assign q = {shift2[l2], shift1[l1]};
+endmodule
+
+module $__XILINX_SHREG_(input C, D, input [1:0] L, output Q);
+parameter CLKPOL = 1;
+parameter ENPOL = 1;
+parameter DEPTH = 1;
+parameter [DEPTH-1:0] INIT = {DEPTH{1'b0}};
+reg [DEPTH-1:0] r = INIT;
+wire clk = C ^ CLKPOL;
+always @(posedge C)
+    r <= { r[DEPTH-2:0], D };
+assign Q = r[L];
+endmodule
diff --git a/tests/various/shregmap.ys b/tests/various/shregmap.ys
new file mode 100644
index 000000000..d644a88aa
--- /dev/null
+++ b/tests/various/shregmap.ys
@@ -0,0 +1,66 @@
+read_verilog shregmap.v
+design -save read
+
+design -copy-to model $__SHREG_DFF_P_
+hierarchy -top shregmap_static_test
+prep
+design -save gold
+
+techmap
+shregmap -init
+
+opt
+
+stat
+# show -width
+select -assert-count 1 t:$_DFF_P_
+select -assert-count 2 t:$__SHREG_DFF_P_
+
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+design -copy-from model -as $__SHREG_DFF_P_ \$__SHREG_DFF_P_
+prep
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports -seq 5 miter
+
+design -load gold
+stat
+
+design -load gate
+stat
+
+##########
+
+design -load read
+design -copy-to model $__XILINX_SHREG_
+hierarchy -top shregmap_variable_test
+prep
+design -save gold
+
+simplemap t:$dff t:$dffe
+shregmap -tech xilinx
+
+stat
+# show -width
+write_verilog -noexpr -norename
+select -assert-count 1 t:$_DFF_P_
+select -assert-count 2 t:$__XILINX_SHREG_
+
+design -stash gate
+
+design -import gold -as gold
+design -import gate -as gate
+design -copy-from model -as $__XILINX_SHREG_ \$__XILINX_SHREG_
+prep
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports -seq 5 miter
+
+design -load gold
+stat
+
+design -load gate
+stat
diff --git a/tests/various/signext.ys b/tests/various/signext.ys
new file mode 100644
index 000000000..0c8d671e7
--- /dev/null
+++ b/tests/various/signext.ys
@@ -0,0 +1,33 @@
+
+read_verilog -formal <<EOT
+module gate(input clk, output [32:0] o, p, q, r, s, t, u);
+assign o = 'bx;
+assign p = 1'bx;
+assign q = 'bz;
+assign r = 1'bz;
+assign s = 1'b0;
+assign t = 'b1;
+assign u = -'sb1;
+endmodule
+EOT
+
+proc
+
+## Equivalence checking
+
+read_verilog -formal <<EOT
+module gold(input clk, output [32:0] o, p, q, r, s, t, u);
+assign o = {33{1'bx}};
+assign p = {{32{1'b0}}, 1'bx};
+assign q = {33{1'bz}};
+assign r = {{32{1'b0}}, 1'bz};
+assign s = {33{1'b0}};
+assign t = {{32{1'b0}}, 1'b1};
+assign u = {33{1'b1}};
+endmodule
+EOT
+
+proc
+
+miter -equiv -flatten -make_assert -make_outputs gold gate miter
+sat -verify -prove-asserts -show-ports -enable_undef miter