Merge branch 'master' into xaig

115 files changed, 5842 insertions, 710 deletions

diff --git a/.github/issue_template.md b/.github/issue_template.md
index 4563a71de..5a0723c3e 100644
--- a/.github/issue_template.md
+++ b/.github/issue_template.md
@@ -4,6 +4,17 @@
 all necessary source files. (You can simply drag&drop a .zip file into
 the issue editor.)*
 
+Also, make sure that the issue is actually reproducable in current git
+master of Yosys.
+
+See https://stackoverflow.com/help/mcve for some information on how to
+create a Minimal, Complete, and Verifiable example (MCVE).
+
+Please do not waste our time with issues that lack sufficient information
+to reproduce the issue easily. We will simply close those issues.
+
+Contact https://www.symbioticeda.com/ if you need commercial support for Yosys.
+
 ## Expected behavior
 
 *Please describe the behavior you would have expected from the tool.*
@@ -11,6 +22,3 @@ the issue editor.)*
 ## Actual behavior
 
 *Please describe how the behavior you see differs from the expected behavior.*
-
-**Important Note:** Nobody will be able to help you and/or fix the issue if you
-do not provide sufficient information for reproducing the problem.
diff --git a/.gitignore b/.gitignore
index 48ce458c7..e24f7975a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -24,6 +24,8 @@
 /yosys-abc.exe
 /yosys-config
 /yosys-smtbmc
+/yosys-smtbmc.exe
+/yosys-smtbmc-script.py
 /yosys-filterlib
 /yosys-filterlib.exe
 /kernel/version_*.cc
diff --git a/.travis.yml b/.travis.yml
index 8aacbb8b1..7c6e4e43c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -132,11 +132,11 @@ matrix:
       env:
         - MATRIX_EVAL="CONFIG=clang && CC=clang-5.0 && CXX=clang++-5.0"
 
-    # Latest clang on Mac OS X
-    - os: osx
-      osx_image: xcode9.4
-      env:
-        - MATRIX_EVAL="CONFIG=clang && CC=clang && CXX=clang++"
+#   # Latest clang on Mac OS X
+#   - os: osx
+#     osx_image: xcode9.4
+#     env:
+#       - MATRIX_EVAL="CONFIG=clang && CC=clang && CXX=clang++"
 
 before_install:
   - ./.travis/setup.sh
diff --git a/Makefile b/Makefile
index c233b0a41..9bc13dcdd 100644
--- a/Makefile
+++ b/Makefile
@@ -10,6 +10,7 @@ CONFIG := clang
 # features (the more the better)
 ENABLE_TCL := 1
 ENABLE_ABC := 1
+ENABLE_GLOB := 1
 ENABLE_PLUGINS := 1
 ENABLE_READLINE := 1
 ENABLE_EDITLINE := 0
@@ -298,6 +299,10 @@ LDLIBS += -ldl
 endif
 endif
 
+ifeq ($(ENABLE_GLOB),1)
+CXXFLAGS += -DYOSYS_ENABLE_GLOB
+endif
+
 ifeq ($(ENABLE_TCL),1)
 TCL_VERSION ?= tcl$(shell bash -c "tclsh <(echo 'puts [info tclversion]')")
 ifeq ($(OS), FreeBSD)
@@ -571,7 +576,7 @@ test: $(TARGETS) $(EXTRA_TARGETS)
 	+cd tests/simple && bash run-test.sh $(SEEDOPT)
 	+cd tests/hana && bash run-test.sh $(SEEDOPT)
 	+cd tests/asicworld && bash run-test.sh $(SEEDOPT)
-	+cd tests/realmath && bash run-test.sh $(SEEDOPT)
+	# +cd tests/realmath && bash run-test.sh $(SEEDOPT)
 	+cd tests/share && bash run-test.sh $(SEEDOPT)
 	+cd tests/fsm && bash run-test.sh $(SEEDOPT)
 	+cd tests/techmap && bash run-test.sh
diff --git a/README.md b/README.md
index 883f2b0a5..4048ecbc7 100644
--- a/README.md
+++ b/README.md
@@ -34,11 +34,24 @@ compatible license that is similar in terms to the MIT license
 or the 2-clause BSD license).
 
 
-Web Site
-========
+Web Site and Other Resources
+============================
 
 More information and documentation can be found on the Yosys web site:
-http://www.clifford.at/yosys/
+- http://www.clifford.at/yosys/
+
+The "Documentation" page on the web site contains links to more resources,
+including a manual that even describes some of the Yosys internals:
+- http://www.clifford.at/yosys/documentation.html
+
+The file `CodingReadme` in this directory contains additional information
+for people interested in using the Yosys C++ APIs.
+
+Users interested in formal verification might want to use the formal verification
+front-end for Yosys, SymbiYosys:
+- https://symbiyosys.readthedocs.io/en/latest/
+- https://github.com/YosysHQ/SymbiYosys
+
 
 Setup
 ======
@@ -92,12 +105,15 @@ Makefile.
 To build Yosys simply type 'make' in this directory.
 
 	$ make
-	$ make test
 	$ sudo make install
 
 Note that this also downloads, builds and installs ABC (using yosys-abc
 as executable name).
 
+Tests are located in the tests subdirectory and can be executed using the test target. Note that you need gawk as well as a recent version of iverilog (i.e. build from git). Then, execute tests via:
+
+	$ make test
+
 Getting Started
 ===============
 
@@ -296,6 +312,12 @@ Verilog Attributes and non-standard features
   passes to identify input and output ports of cells. The Verilog backend
   also does not output blackbox modules on default.
 
+- The ``dynports'' attribute is used by the Verilog front-end to mark modules
+  that have ports with a width that depends on a parameter.
+
+- The ``hdlname'' attribute is used by some passes to document the original
+  (HDL) name of a module when renaming a module.
+
 - The ``keep`` attribute on cells and wires is used to mark objects that should
   never be removed by the optimizer. This is used for example for cells that
   have hidden connections that are not part of the netlist, such as IO pads.
diff --git a/backends/btor/btor.cc b/backends/btor/btor.cc
index 53359bd7b..55c494996 100644
--- a/backends/btor/btor.cc
+++ b/backends/btor/btor.cc
@@ -615,6 +615,7 @@ struct BtorWorker
 		{
 			int abits = cell->getParam("\\ABITS").as_int();
 			int width = cell->getParam("\\WIDTH").as_int();
+			int nwords = cell->getParam("\\SIZE").as_int();
 			int rdports = cell->getParam("\\RD_PORTS").as_int();
 			int wrports = cell->getParam("\\WR_PORTS").as_int();
 
@@ -641,6 +642,52 @@ struct BtorWorker
 			int data_sid = get_bv_sid(width);
 			int bool_sid = get_bv_sid(1);
 			int sid = get_mem_sid(abits, width);
+
+			Const initdata = cell->getParam("\\INIT");
+			initdata.exts(nwords*width);
+			int nid_init_val = -1;
+
+			if (!initdata.is_fully_undef())
+			{
+				bool constword = true;
+				Const firstword = initdata.extract(0, width);
+
+				for (int i = 1; i < nwords; i++) {
+					Const thisword = initdata.extract(i*width, width);
+					if (thisword != firstword) {
+						constword = false;
+						break;
+					}
+				}
+
+				if (constword)
+				{
+					if (verbose)
+						btorf("; initval = %s\n", log_signal(firstword));
+					nid_init_val = get_sig_nid(firstword);
+				}
+				else
+				{
+					int nid_init_val = next_nid++;
+					btorf("%d state %d\n", nid_init_val, sid);
+
+					for (int i = 0; i < nwords; i++) {
+						Const thisword = initdata.extract(i*width, width);
+						if (thisword.is_fully_undef())
+							continue;
+						Const thisaddr(i, abits);
+						int nid_thisword = get_sig_nid(thisword);
+						int nid_thisaddr = get_sig_nid(thisaddr);
+						int last_nid_init_val = nid_init_val;
+						nid_init_val = next_nid++;
+						if (verbose)
+							btorf("; initval[%d] = %s\n", i, log_signal(thisword));
+						btorf("%d write %d %d %d %d\n", nid_init_val, sid, last_nid_init_val, nid_thisaddr, nid_thisword);
+					}
+				}
+			}
+
+
 			int nid = next_nid++;
 			int nid_head = nid;
 
@@ -649,6 +696,12 @@ struct BtorWorker
 			else
 				btorf("%d state %d %s\n", nid, sid, log_id(cell));
 
+			if (nid_init_val >= 0)
+			{
+				int nid_init = next_nid++;
+				btorf("%d init %d %d %d\n", nid_init, sid, nid, nid_init_val);
+			}
+
 			if (asyncwr)
 			{
 				for (int port = 0; port < wrports; port++)
@@ -932,9 +985,8 @@ struct BtorWorker
 
 			btorf_push(stringf("output %s", log_id(wire)));
 
-			int sid = get_bv_sid(GetSize(wire));
 			int nid = get_sig_nid(wire);
-			btorf("%d output %d %d %s\n", next_nid++, sid, nid, log_id(wire));
+			btorf("%d output %d %s\n", next_nid++, nid, log_id(wire));
 
 			btorf_pop(stringf("output %s", log_id(wire)));
 		}
diff --git a/backends/edif/edif.cc b/backends/edif/edif.cc
index 2d25f879d..7e30b67af 100644
--- a/backends/edif/edif.cc
+++ b/backends/edif/edif.cc
@@ -130,7 +130,7 @@ struct EdifBackend : public Backend {
 		bool port_rename = false;
 		bool attr_properties = false;
 		std::map<RTLIL::IdString, std::map<RTLIL::IdString, int>> lib_cell_ports;
-		bool nogndvcc = false, gndvccy = true;
+		bool nogndvcc = false, gndvccy = false;
 		CellTypes ct(design);
 		EdifNames edif_names;
 
diff --git a/backends/firrtl/firrtl.cc b/backends/firrtl/firrtl.cc
index 0917ecba6..ed6e9f8ee 100644
--- a/backends/firrtl/firrtl.cc
+++ b/backends/firrtl/firrtl.cc
@@ -106,6 +106,95 @@ struct FirrtlWorker
 	RTLIL::Design *design;
 	std::string indent;
 
+	// Define read/write ports and memories.
+	// We'll collect their definitions and emit the corresponding FIRRTL definitions at the appropriate point in module construction.
+	// For the moment, we don't handle $readmemh or $readmemb.
+	// These will be part of a subsequent PR.
+	struct read_port {
+		string name;
+		bool clk_enable;
+		bool clk_parity;
+		bool transparent;
+		RTLIL::SigSpec clk;
+		RTLIL::SigSpec ena;
+		RTLIL::SigSpec addr;
+		read_port(string name, bool clk_enable, bool clk_parity, bool transparent, RTLIL::SigSpec clk, RTLIL::SigSpec ena, RTLIL::SigSpec addr) : name(name), clk_enable(clk_enable), clk_parity(clk_parity), transparent(transparent), clk(clk), ena(ena), addr(addr) {
+			// Current (3/13/2019) conventions:
+			//  generate a constant 0 for clock and a constant 1 for enable if they are undefined.
+			if (!clk.is_fully_def())
+				this->clk = SigSpec(RTLIL::Const(0, 1));
+			if (!ena.is_fully_def())
+				this->ena = SigSpec(RTLIL::Const(1, 1));
+		}
+		string gen_read(const char * indent) {
+			string addr_expr = make_expr(addr);
+			string ena_expr = make_expr(ena);
+			string clk_expr = make_expr(clk);
+			string addr_str = stringf("%s%s.addr <= %s\n", indent, name.c_str(), addr_expr.c_str());
+			string ena_str = stringf("%s%s.en <= %s\n", indent, name.c_str(), ena_expr.c_str());
+			string clk_str = stringf("%s%s.clk <= asClock(%s)\n", indent, name.c_str(), clk_expr.c_str());
+			return addr_str + ena_str + clk_str;
+		}
+	};
+	struct write_port : read_port {
+		RTLIL::SigSpec mask;
+		write_port(string name, bool clk_enable, bool clk_parity, bool transparent, RTLIL::SigSpec clk, RTLIL::SigSpec ena, RTLIL::SigSpec addr, RTLIL::SigSpec mask) : read_port(name, clk_enable, clk_parity, transparent, clk, ena, addr), mask(mask) {
+			if (!clk.is_fully_def())
+				this->clk = SigSpec(RTLIL::Const(0));
+			if (!ena.is_fully_def())
+				this->ena = SigSpec(RTLIL::Const(0));
+			if (!mask.is_fully_def())
+				this->ena = SigSpec(RTLIL::Const(1));
+		}
+	  string gen_read(const char * /* indent */) {
+			log_error("gen_read called on write_port: %s\n", name.c_str());
+			return stringf("gen_read called on write_port: %s\n", name.c_str());
+		}
+		string gen_write(const char * indent) {
+			string addr_expr = make_expr(addr);
+			string ena_expr = make_expr(ena);
+			string clk_expr = make_expr(clk);
+			string mask_expr = make_expr(mask);
+			string mask_str = stringf("%s%s.mask <= %s\n", indent, name.c_str(), mask_expr.c_str());
+			string addr_str = stringf("%s%s.addr <= %s\n", indent, name.c_str(), addr_expr.c_str());
+			string ena_str = stringf("%s%s.en <= %s\n", indent, name.c_str(), ena_expr.c_str());
+			string clk_str = stringf("%s%s.clk <= asClock(%s)\n", indent, name.c_str(), clk_expr.c_str());
+			return addr_str + ena_str + clk_str + mask_str;
+		}
+	};
+	/* Memories defined within this module. */
+	 struct memory {
+		 string name;					// memory name
+		 int abits;						// number of address bits
+		 int size;						// size (in units) of the memory
+		 int width;						// size (in bits) of each element
+		 int read_latency;
+		 int write_latency;
+		 vector<read_port> read_ports;
+		 vector<write_port> write_ports;
+		 std::string init_file;
+		 std::string init_file_srcFileSpec;
+		 memory(string name, int abits, int size, int width) : name(name), abits(abits), size(size), width(width), read_latency(0), write_latency(1), init_file(""), init_file_srcFileSpec("") {}
+		 memory() : read_latency(0), write_latency(1), init_file(""), init_file_srcFileSpec(""){}
+		 void add_memory_read_port(read_port &rp) {
+			 read_ports.push_back(rp);
+		 }
+		 void add_memory_write_port(write_port &wp) {
+			 write_ports.push_back(wp);
+		 }
+		 void add_memory_file(std::string init_file, std::string init_file_srcFileSpec) {
+			 this->init_file = init_file;
+			 this->init_file_srcFileSpec = init_file_srcFileSpec;
+		 }
+
+	 };
+	dict<string, memory> memories;
+
+	void register_memory(memory &m)
+	{
+		memories[m.name] = m;
+	}
+
 	void register_reverse_wire_map(string id, SigSpec sig)
 	{
 		for (int i = 0; i < GetSize(sig); i++)
@@ -116,7 +205,7 @@ struct FirrtlWorker
 	{
 	}
 
-	string make_expr(const SigSpec &sig)
+	static string make_expr(const SigSpec &sig)
 	{
 		string expr;
 
@@ -165,11 +254,9 @@ struct FirrtlWorker
 
 	std::string fid(RTLIL::IdString internal_id)
 	{
-		const char *str = internal_id.c_str();
-		return *str == '\\' ? str + 1 : str;
+		return make_id(internal_id);
 	}
 
-
 	std::string cellname(RTLIL::Cell *cell)
 	{
 		return fid(cell->name).c_str();
@@ -219,29 +306,42 @@ struct FirrtlWorker
 			if (it->second.size() > 0) {
 				const SigSpec &secondSig = it->second;
 				const std::string firstName = cell_name + "." + make_id(it->first);
-				const std::string secondName = make_expr(secondSig);
+				const std::string secondExpr = make_expr(secondSig);
 				// Find the direction for this port.
 				FDirection dir = getPortFDirection(it->first, instModule);
-				std::string source, sink;
+				std::string sourceExpr, sinkExpr;
+				const SigSpec *sinkSig = nullptr;
 				switch (dir) {
 					case FD_INOUT:
 						log_warning("Instance port connection %s.%s is INOUT; treating as OUT\n", cell_type.c_str(), log_signal(it->second));
 					case FD_OUT:
-						source = firstName;
-						sink = secondName;
+						sourceExpr = firstName;
+						sinkExpr = secondExpr;
+						sinkSig = &secondSig;
 						break;
 					case FD_NODIRECTION:
 						log_warning("Instance port connection %s.%s is NODIRECTION; treating as IN\n", cell_type.c_str(), log_signal(it->second));
 						/* FALL_THROUGH */
 					case FD_IN:
-						source = secondName;
-						sink = firstName;
+						sourceExpr = secondExpr;
+						sinkExpr = firstName;
 						break;
 					default:
 						log_error("Instance port %s.%s unrecognized connection direction 0x%x !\n", cell_type.c_str(), log_signal(it->second), dir);
 						break;
 				}
-				wire_exprs.push_back(stringf("\n%s%s <= %s", indent.c_str(), sink.c_str(), source.c_str()));
+				// Check for subfield assignment.
+				std::string bitsString = "bits(";
+				if (sinkExpr.substr(0, bitsString.length()) == bitsString ) {
+					if (sinkSig == nullptr)
+						log_error("Unknown subfield %s.%s\n", cell_type.c_str(), sinkExpr.c_str());
+					// Don't generate the assignment here.
+					// Add the source and sink to the "reverse_wire_map" and we'll output the assignment
+					//  as part of the coalesced subfield assignments for this wire.
+					register_reverse_wire_map(sourceExpr, *sinkSig);
+				} else {
+					wire_exprs.push_back(stringf("\n%s%s <= %s", indent.c_str(), sinkExpr.c_str(), sourceExpr.c_str()));
+				}
 			}
 		}
 		wire_exprs.push_back(stringf("\n"));
@@ -504,6 +604,7 @@ struct FirrtlWorker
 				int abits = cell->parameters.at("\\ABITS").as_int();
 				int width = cell->parameters.at("\\WIDTH").as_int();
 				int size = cell->parameters.at("\\SIZE").as_int();
+				memory m(mem_id, abits, size, width);
 				int rd_ports = cell->parameters.at("\\RD_PORTS").as_int();
 				int wr_ports = cell->parameters.at("\\WR_PORTS").as_int();
 
@@ -520,33 +621,24 @@ struct FirrtlWorker
 				if (offset != 0)
 					log_error("Memory with nonzero offset: %s.%s\n", log_id(module), log_id(cell));
 
-				cell_exprs.push_back(stringf("    mem %s:\n", mem_id.c_str()));
-				cell_exprs.push_back(stringf("      data-type => UInt<%d>\n", width));
-				cell_exprs.push_back(stringf("      depth => %d\n", size));
-
-				for (int i = 0; i < rd_ports; i++)
-					cell_exprs.push_back(stringf("      reader => r%d\n", i));
-
-				for (int i = 0; i < wr_ports; i++)
-					cell_exprs.push_back(stringf("      writer => w%d\n", i));
-
-				cell_exprs.push_back(stringf("      read-latency => 0\n"));
-				cell_exprs.push_back(stringf("      write-latency => 1\n"));
-				cell_exprs.push_back(stringf("      read-under-write => undefined\n"));
-
 				for (int i = 0; i < rd_ports; i++)
 				{
 					if (rd_clk_enable[i] != State::S0)
 						log_error("Clocked read port %d on memory %s.%s.\n", i, log_id(module), log_id(cell));
 
+					SigSpec addr_sig = cell->getPort("\\RD_ADDR").extract(i*abits, abits);
 					SigSpec data_sig = cell->getPort("\\RD_DATA").extract(i*width, width);
-					string addr_expr = make_expr(cell->getPort("\\RD_ADDR").extract(i*abits, abits));
-
-					cell_exprs.push_back(stringf("    %s.r%d.addr <= %s\n", mem_id.c_str(), i, addr_expr.c_str()));
-					cell_exprs.push_back(stringf("    %s.r%d.en <= UInt<1>(1)\n", mem_id.c_str(), i));
-					cell_exprs.push_back(stringf("    %s.r%d.clk <= asClock(UInt<1>(0))\n", mem_id.c_str(), i));
-
-					register_reverse_wire_map(stringf("%s.r%d.data", mem_id.c_str(), i), data_sig);
+					string addr_expr = make_expr(addr_sig);
+					string name(stringf("%s.r%d", m.name.c_str(), i));
+					bool clk_enable = false;
+					bool clk_parity = true;
+					bool transparency = false;
+					SigSpec ena_sig = RTLIL::SigSpec(RTLIL::State::S1, 1);
+					SigSpec clk_sig = RTLIL::SigSpec(RTLIL::State::S0, 1);
+					read_port rp(name, clk_enable, clk_parity, transparency, clk_sig, ena_sig, addr_sig);
+					m.add_memory_read_port(rp);
+					cell_exprs.push_back(rp.gen_read(indent.c_str()));
+					register_reverse_wire_map(stringf("%s.data", name.c_str()), data_sig);
 				}
 
 				for (int i = 0; i < wr_ports; i++)
@@ -557,9 +649,16 @@ struct FirrtlWorker
 					if (wr_clk_polarity[i] != State::S1)
 						log_error("Negedge write port %d on memory %s.%s.\n", i, log_id(module), log_id(cell));
 
-					string addr_expr = make_expr(cell->getPort("\\WR_ADDR").extract(i*abits, abits));
-					string data_expr = make_expr(cell->getPort("\\WR_DATA").extract(i*width, width));
-					string clk_expr = make_expr(cell->getPort("\\WR_CLK").extract(i));
+					string name(stringf("%s.w%d", m.name.c_str(), i));
+					bool clk_enable = true;
+					bool clk_parity = true;
+					bool transparency = false;
+					SigSpec addr_sig =cell->getPort("\\WR_ADDR").extract(i*abits, abits);
+					string addr_expr = make_expr(addr_sig);
+					SigSpec data_sig =cell->getPort("\\WR_DATA").extract(i*width, width);
+					string data_expr = make_expr(data_sig);
+					SigSpec clk_sig = cell->getPort("\\WR_CLK").extract(i);
+					string clk_expr = make_expr(clk_sig);
 
 					SigSpec wen_sig = cell->getPort("\\WR_EN").extract(i*width, width);
 					string wen_expr = make_expr(wen_sig[0]);
@@ -568,13 +667,50 @@ struct FirrtlWorker
 						if (wen_sig[0] != wen_sig[i])
 							log_error("Complex write enable on port %d on memory %s.%s.\n", i, log_id(module), log_id(cell));
 
-					cell_exprs.push_back(stringf("    %s.w%d.addr <= %s\n", mem_id.c_str(), i, addr_expr.c_str()));
-					cell_exprs.push_back(stringf("    %s.w%d.data <= %s\n", mem_id.c_str(), i, data_expr.c_str()));
-					cell_exprs.push_back(stringf("    %s.w%d.en <= %s\n", mem_id.c_str(), i, wen_expr.c_str()));
-					cell_exprs.push_back(stringf("    %s.w%d.mask <= UInt<1>(1)\n", mem_id.c_str(), i));
-					cell_exprs.push_back(stringf("    %s.w%d.clk <= asClock(%s)\n", mem_id.c_str(), i, clk_expr.c_str()));
+					SigSpec mask_sig = RTLIL::SigSpec(RTLIL::State::S1, 1);
+					write_port wp(name, clk_enable, clk_parity, transparency, clk_sig, wen_sig[0], addr_sig, mask_sig);
+					m.add_memory_write_port(wp);
+					cell_exprs.push_back(stringf("%s%s.data <= %s\n", indent.c_str(), name.c_str(), data_expr.c_str()));
+					cell_exprs.push_back(wp.gen_write(indent.c_str()));
 				}
+				register_memory(m);
+				continue;
+			}
 
+			if (cell->type.in("$memwr", "$memrd", "$meminit"))
+			{
+				std::string cell_type = fid(cell->type);
+				std::string mem_id = make_id(cell->parameters["\\MEMID"].decode_string());
+				memory *mp = nullptr;
+				if (cell->type == "$meminit" ) {
+					log_error("$meminit (%s.%s.%s) currently unsupported\n", log_id(module), log_id(cell), mem_id.c_str());
+				} else {
+					// It's a $memwr or $memrd. Remember the read/write port parameters for the eventual FIRRTL memory definition.
+					auto addrSig = cell->getPort("\\ADDR");
+					auto dataSig = cell->getPort("\\DATA");
+					auto enableSig = cell->getPort("\\EN");
+					auto clockSig = cell->getPort("\\CLK");
+					Const clk_enable = cell->parameters.at("\\CLK_ENABLE");
+					Const clk_polarity = cell->parameters.at("\\CLK_POLARITY");
+
+					mp = &memories.at(mem_id);
+					int portNum = 0;
+					bool transparency = false;
+					string data_expr = make_expr(dataSig);
+					if (cell->type.in("$memwr")) {
+						portNum = (int) mp->write_ports.size();
+						write_port wp(stringf("%s.w%d", mem_id.c_str(), portNum), clk_enable.as_bool(), clk_polarity.as_bool(),  transparency, clockSig, enableSig, addrSig, dataSig);
+						mp->add_memory_write_port(wp);
+						cell_exprs.push_back(stringf("%s%s.data <= %s\n", indent.c_str(), wp.name.c_str(), data_expr.c_str()));
+						cell_exprs.push_back(wp.gen_write(indent.c_str()));
+					} else if (cell->type.in("$memrd")) {
+						portNum = (int) mp->read_ports.size();
+						read_port rp(stringf("%s.r%d", mem_id.c_str(), portNum), clk_enable.as_bool(), clk_polarity.as_bool(),  transparency, clockSig, enableSig, addrSig);
+						mp->add_memory_read_port(rp);
+						cell_exprs.push_back(rp.gen_read(indent.c_str()));
+						register_reverse_wire_map(stringf("%s.data", rp.name.c_str()), dataSig);
+					}
+				}
 				continue;
 			}
 
@@ -752,6 +888,24 @@ struct FirrtlWorker
 
 		f << stringf("\n");
 
+		// If we have any memory definitions, output them.
+		for (auto kv : memories) {
+			memory m = kv.second;
+			f << stringf("    mem %s:\n", m.name.c_str());
+			f << stringf("      data-type => UInt<%d>\n", m.width);
+			f << stringf("      depth => %d\n", m.size);
+			for (int i = 0; i < (int) m.read_ports.size(); i += 1) {
+				f << stringf("      reader => r%d\n", i);
+			}
+			for (int i = 0; i < (int) m.write_ports.size(); i += 1) {
+				f << stringf("      writer => w%d\n", i);
+			}
+			f << stringf("      read-latency => %d\n", m.read_latency);
+			f << stringf("      write-latency => %d\n", m.write_latency);
+			f << stringf("      read-under-write => undefined\n");
+		}
+		f << stringf("\n");
+
 		for (auto str : cell_exprs)
 			f << str;
 
diff --git a/backends/ilang/ilang_backend.cc b/backends/ilang/ilang_backend.cc
index 4c58ea087..dc39e5e08 100644
--- a/backends/ilang/ilang_backend.cc
+++ b/backends/ilang/ilang_backend.cc
@@ -204,7 +204,7 @@ void ILANG_BACKEND::dump_proc_switch(std::ostream &f, std::string indent, const
 		f << stringf("%s  case ", indent.c_str());
 		for (size_t i = 0; i < (*it)->compare.size(); i++) {
 			if (i > 0)
-				f << stringf(", ");
+				f << stringf(" , ");
 			dump_sigspec(f, (*it)->compare[i]);
 		}
 		f << stringf("\n");
diff --git a/backends/protobuf/protobuf.cc b/backends/protobuf/protobuf.cc
index f56147cef..549fc73ae 100644
--- a/backends/protobuf/protobuf.cc
+++ b/backends/protobuf/protobuf.cc
@@ -48,7 +48,7 @@ struct ProtobufDesignSerializer
 
 	ProtobufDesignSerializer(bool use_selection, bool aig_mode) :
 			aig_mode_(aig_mode), use_selection_(use_selection) { }
-	
+
 	string get_name(IdString name)
 	{
 		return RTLIL::unescape_id(name);
@@ -60,7 +60,7 @@ struct ProtobufDesignSerializer
 	{
 		for (auto &param : parameters) {
 			std::string key = get_name(param.first);
-			
+
 
 			yosys::pb::Parameter pb_param;
 
@@ -207,7 +207,7 @@ struct ProtobufDesignSerializer
 			(*models)[aig.name] = pb_model;
 		}
 	}
-	
+
 	void serialize_design(yosys::pb::Design *pb, Design *design)
 	{
 		GOOGLE_PROTOBUF_VERIFY_VERSION;
diff --git a/backends/smt2/Makefile.inc b/backends/smt2/Makefile.inc
index dce82f01a..92941d4cf 100644
--- a/backends/smt2/Makefile.inc
+++ b/backends/smt2/Makefile.inc
@@ -3,14 +3,30 @@ OBJS += backends/smt2/smt2.o
 
 ifneq ($(CONFIG),mxe)
 ifneq ($(CONFIG),emcc)
+
+# MSYS targets support yosys-smtbmc, but require a launcher script
+ifeq ($(CONFIG),$(filter $(CONFIG),msys2 msys2-64))
+TARGETS += yosys-smtbmc.exe yosys-smtbmc-script.py
+# Needed to find the Python interpreter for yosys-smtbmc scripts.
+# Override if necessary, it is only used for msys2 targets.
+PYTHON := $(shell cygpath -w -m $(PREFIX)/bin/python3)
+
+yosys-smtbmc-script.py: backends/smt2/smtbmc.py
+	$(P) sed -e 's|##yosys-sys-path##|sys.path += [os.path.dirname(os.path.realpath(__file__)) + p for p in ["/share/python3", "/../share/yosys/python3"]]|;' \
+		-e "s|#!/usr/bin/env python3|#!$(PYTHON)|" < $< > $@
+
+yosys-smtbmc.exe: misc/launcher.c yosys-smtbmc-script.py
+	$(P) gcc -DGUI=0 -O -s -o $@ $<
+# Other targets
+else
 TARGETS += yosys-smtbmc
 
 yosys-smtbmc: backends/smt2/smtbmc.py
 	$(P) sed 's|##yosys-sys-path##|sys.path += [os.path.dirname(os.path.realpath(__file__)) + p for p in ["/share/python3", "/../share/yosys/python3"]]|;' < $< > $@.new
 	$(Q) chmod +x $@.new
 	$(Q) mv $@.new $@
+endif
 
 $(eval $(call add_share_file,share/python3,backends/smt2/smtio.py))
 endif
 endif
-
diff --git a/backends/smt2/smt2.cc b/backends/smt2/smt2.cc
index 418f8d766..688535f33 100644
--- a/backends/smt2/smt2.cc
+++ b/backends/smt2/smt2.cc
@@ -416,6 +416,7 @@ struct Smt2Worker
 		for (char ch : expr) {
 			if (ch == 'A') processed_expr += get_bv(sig_a);
 			else if (ch == 'B') processed_expr += get_bv(sig_b);
+			else if (ch == 'P') processed_expr += get_bv(cell->getPort("\\B"));
 			else if (ch == 'L') processed_expr += is_signed ? "a" : "l";
 			else if (ch == 'U') processed_expr += is_signed ? "s" : "u";
 			else processed_expr += ch;
@@ -554,7 +555,7 @@ struct Smt2Worker
 
 			if (cell->type.in("$shift", "$shiftx")) {
 				if (cell->getParam("\\B_SIGNED").as_bool()) {
-					return export_bvop(cell, stringf("(ite (bvsge B #b%0*d) "
+					return export_bvop(cell, stringf("(ite (bvsge P #b%0*d) "
 							"(bvlshr A B) (bvlshr A (bvneg B)))",
 							GetSize(cell->getPort("\\B")), 0), 's');
 				} else {
@@ -887,8 +888,8 @@ struct Smt2Worker
 
 				string name_a = get_bool(cell->getPort("\\A"));
 				string name_en = get_bool(cell->getPort("\\EN"));
-				decls.push_back(stringf("; yosys-smt2-%s %d %s\n", cell->type.c_str() + 1, id,
-						cell->attributes.count("\\src") ? cell->attributes.at("\\src").decode_string().c_str() : get_id(cell)));
+				string infostr = (cell->name[0] == '$' && cell->attributes.count("\\src")) ? cell->attributes.at("\\src").decode_string() : get_id(cell);
+				decls.push_back(stringf("; yosys-smt2-%s %d %s\n", cell->type.c_str() + 1, id, infostr.c_str()));
 
 				if (cell->type == "$cover")
 					decls.push_back(stringf("(define-fun |%s_%c %d| ((state |%s_s|)) Bool (and %s %s)) ; %s\n",
@@ -1103,20 +1104,27 @@ struct Smt2Worker
 							break;
 
 						Const initword = init_data.extract(i*width, width, State::Sx);
+						Const initmask = initword;
 						bool gen_init_constr = false;
 
-						for (auto bit : initword.bits)
-							if (bit == State::S0 || bit == State::S1)
+						for (int k = 0; k < GetSize(initword); k++) {
+							if (initword[k] == State::S0 || initword[k] == State::S1) {
 								gen_init_constr = true;
+								initmask[k] = State::S1;
+							} else {
+								initmask[k] = State::S0;
+								initword[k] = State::S0;
+							}
+						}
 
 						if (gen_init_constr)
 						{
 							if (statebv)
 								/* FIXME */;
 							else
-								init_list.push_back(stringf("(= (select (|%s#%d#0| state) #b%s) #b%s) ; %s[%d]",
+								init_list.push_back(stringf("(= (bvand (select (|%s#%d#0| state) #b%s) #b%s) #b%s) ; %s[%d]",
 										get_id(module), arrayid, Const(i, abits).as_string().c_str(),
-										initword.as_string().c_str(), get_id(cell), i));
+										initmask.as_string().c_str(), initword.as_string().c_str(), get_id(cell), i));
 						}
 					}
 				}
diff --git a/backends/smt2/smtbmc.py b/backends/smt2/smtbmc.py
index 94a5e2da0..445a42e0d 100644
--- a/backends/smt2/smtbmc.py
+++ b/backends/smt2/smtbmc.py
@@ -1484,11 +1484,11 @@ else:  # not tempind, covermode
                             smt_assert_antecedent("(|%s_h| s%d)" % (topmod, i))
                             smt_assert_antecedent("(|%s_t| s%d s%d)" % (topmod, i-1, i))
                             smt_assert_consequent(get_constr_expr(constr_assumes, i))
-                    print_msg("Re-solving with appended steps..")
-                    if smt_check_sat() == "unsat":
-                        print("%s Cannot appended steps without violating assumptions!" % smt.timestamp())
-                        retstatus = False
-                        break
+                        print_msg("Re-solving with appended steps..")
+                        if smt_check_sat() == "unsat":
+                            print("%s Cannot appended steps without violating assumptions!" % smt.timestamp())
+                            retstatus = False
+                            break
                     print_anyconsts(step)
                     for i in range(step, last_check_step+1):
                         print_failed_asserts(i)
diff --git a/backends/verilog/verilog_backend.cc b/backends/verilog/verilog_backend.cc
index d351a6266..83d83f488 100644
--- a/backends/verilog/verilog_backend.cc
+++ b/backends/verilog/verilog_backend.cc
@@ -33,7 +33,7 @@
 USING_YOSYS_NAMESPACE
 PRIVATE_NAMESPACE_BEGIN
 
-bool verbose, norename, noattr, attr2comment, noexpr, nodec, nohex, nostr, defparam, decimal;
+bool verbose, norename, noattr, attr2comment, noexpr, nodec, nohex, nostr, defparam, decimal, siminit;
 int auto_name_counter, auto_name_offset, auto_name_digits;
 std::map<RTLIL::IdString, int> auto_name_map;
 std::set<RTLIL::IdString> reg_wires, reg_ct;
@@ -1310,7 +1310,7 @@ void dump_cell(std::ostream &f, std::string indent, RTLIL::Cell *cell)
 		}
 	}
 
-	if (reg_ct.count(cell->type) && cell->hasPort("\\Q")) {
+	if (siminit && reg_ct.count(cell->type) && cell->hasPort("\\Q")) {
 		std::stringstream ss;
 		dump_reg_init(ss, cell->getPort("\\Q"));
 		if (!ss.str().empty()) {
@@ -1607,6 +1607,10 @@ struct VerilogBackend : public Backend {
 		log("        without this option all internal cells are converted to Verilog\n");
 		log("        expressions.\n");
 		log("\n");
+		log("    -siminit\n");
+		log("        add initial statements with hierarchical refs to initialize FFs when\n");
+		log("        in -noexpr mode.\n");
+		log("\n");
 		log("    -nodec\n");
 		log("        32-bit constant values are by default dumped as decimal numbers,\n");
 		log("        not bit pattern. This option deactivates this feature and instead\n");
@@ -1663,11 +1667,14 @@ struct VerilogBackend : public Backend {
 		nostr = false;
 		defparam = false;
 		decimal = false;
+		siminit = false;
 		auto_prefix = "";
 
 		bool blackboxes = false;
 		bool selected = false;
 
+		auto_name_map.clear();
+		reg_wires.clear();
 		reg_ct.clear();
 
 		reg_ct.insert("$dff");
@@ -1739,6 +1746,10 @@ struct VerilogBackend : public Backend {
 				decimal = true;
 				continue;
 			}
+			if (arg == "-siminit") {
+				siminit = true;
+				continue;
+			}
 			if (arg == "-blackboxes") {
 				blackboxes = true;
 				continue;
@@ -1770,6 +1781,8 @@ struct VerilogBackend : public Backend {
 			dump_module(*f, "", it->second);
 		}
 
+		auto_name_map.clear();
+		reg_wires.clear();
 		reg_ct.clear();
 	}
 } VerilogBackend;
diff --git a/examples/anlogic/.gitignore b/examples/anlogic/.gitignore
new file mode 100644
index 000000000..97c978a15
--- /dev/null
+++ b/examples/anlogic/.gitignore
@@ -0,0 +1,7 @@
+demo.bit
+demo_phy.area
+full.v
+*.log
+*.h
+*.tde
+*.svf
diff --git a/examples/anlogic/README b/examples/anlogic/README
new file mode 100644
index 000000000..35d8e9cb1
--- /dev/null
+++ b/examples/anlogic/README
@@ -0,0 +1,12 @@
+LED Blink project for Anlogic Lichee Tang board.
+
+Follow the install instructions for the Tang Dynasty IDE from given link below.
+
+https://tang.sipeed.com/en/getting-started/installing-td-ide/linux/
+
+
+set TD_HOME env variable to the full path to the TD <TD Install Directory> as follow.
+
+export TD_HOME=<TD Install Directory>
+
+then run "bash build.sh" in this directory.
diff --git a/examples/anlogic/build.sh b/examples/anlogic/build.sh
new file mode 100755
index 000000000..e0f6b4cfe
--- /dev/null
+++ b/examples/anlogic/build.sh
@@ -0,0 +1,4 @@
+#!/bin/bash
+set -ex
+yosys demo.ys
+$TD_HOME/bin/td build.tcl
diff --git a/examples/anlogic/build.tcl b/examples/anlogic/build.tcl
new file mode 100644
index 000000000..06db525c9
--- /dev/null
+++ b/examples/anlogic/build.tcl
@@ -0,0 +1,11 @@
+import_device eagle_s20.db -package BG256
+read_verilog full.v -top demo
+read_adc demo.adc
+optimize_rtl
+map_macro
+map
+pack
+place
+route
+report_area -io_info -file demo_phy.area
+bitgen -bit demo.bit -version 0X0000 -svf demo.svf -svf_comment_on -g ucode:00000000000000000000000000000000
diff --git a/examples/anlogic/demo.adc b/examples/anlogic/demo.adc
new file mode 100644
index 000000000..ec802502e
--- /dev/null
+++ b/examples/anlogic/demo.adc
@@ -0,0 +1,2 @@
+set_pin_assignment {CLK_IN} { LOCATION = K14;  } ##24MHZ
+set_pin_assignment {R_LED} { LOCATION = R3;  } ##R_LED
diff --git a/examples/anlogic/demo.v b/examples/anlogic/demo.v
new file mode 100644
index 000000000..e17db771e
--- /dev/null
+++ b/examples/anlogic/demo.v
@@ -0,0 +1,18 @@
+module demo (
+    input wire CLK_IN,
+    output wire R_LED
+);
+    parameter time1 = 30'd12_000_000;
+    reg led_state;
+    reg [29:0] count;
+
+    always @(posedge CLK_IN)begin
+        if(count == time1)begin
+            count<= 30'd0;
+            led_state <= ~led_state;
+        end
+        else
+            count <= count + 1'b1;
+    end
+    assign R_LED = led_state;
+endmodule
diff --git a/examples/anlogic/demo.ys b/examples/anlogic/demo.ys
new file mode 100644
index 000000000..cb396cc2b
--- /dev/null
+++ b/examples/anlogic/demo.ys
@@ -0,0 +1,3 @@
+read_verilog demo.v
+synth_anlogic -top demo
+write_verilog full.v
diff --git a/examples/igloo2/.gitignore b/examples/igloo2/.gitignore
index ea58efc9f..33b7182d3 100644
--- a/examples/igloo2/.gitignore
+++ b/examples/igloo2/.gitignore
@@ -1,3 +1,4 @@
 /netlist.edn
 /netlist.vm
+/example.stp
 /proj
diff --git a/examples/igloo2/example.pdc b/examples/igloo2/example.pdc
index e6ffd53db..298d9e934 100644
--- a/examples/igloo2/example.pdc
+++ b/examples/igloo2/example.pdc
@@ -1 +1,20 @@
 # Add placement constraints here
+
+set_io clk  -pinname H16 -fixed yes -DIRECTION INPUT
+
+set_io SW1  -pinname H12 -fixed yes -DIRECTION INPUT
+set_io SW2  -pinname H13 -fixed yes -DIRECTION INPUT
+
+set_io LED1 -pinname J16 -fixed yes -DIRECTION OUTPUT
+set_io LED2 -pinname M16 -fixed yes -DIRECTION OUTPUT
+set_io LED3 -pinname K16 -fixed yes -DIRECTION OUTPUT
+set_io LED4 -pinname N16 -fixed yes -DIRECTION OUTPUT
+
+set_io AA   -pinname L12 -fixed yes -DIRECTION OUTPUT
+set_io AB   -pinname L13 -fixed yes -DIRECTION OUTPUT
+set_io AC   -pinname M13 -fixed yes -DIRECTION OUTPUT
+set_io AD   -pinname N15 -fixed yes -DIRECTION OUTPUT
+set_io AE   -pinname L11 -fixed yes -DIRECTION OUTPUT
+set_io AF   -pinname L14 -fixed yes -DIRECTION OUTPUT
+set_io AG   -pinname N14 -fixed yes -DIRECTION OUTPUT
+set_io CA   -pinname M15 -fixed yes -DIRECTION OUTPUT
diff --git a/examples/igloo2/example.sdc b/examples/igloo2/example.sdc
index c6ff94161..f8b487316 100644
--- a/examples/igloo2/example.sdc
+++ b/examples/igloo2/example.sdc
@@ -1 +1,2 @@
 # Add timing constraints here
+create_clock -period 10.000 -waveform {0.000 5.000} [get_ports {clk}]
diff --git a/examples/igloo2/example.v b/examples/igloo2/example.v
index 1a1967d5a..4a9486e50 100644
--- a/examples/igloo2/example.v
+++ b/examples/igloo2/example.v
@@ -1,23 +1,64 @@
 module example (
 	input  clk,
-	input  EN,
+	input  SW1,
+	input  SW2,
 	output LED1,
 	output LED2,
 	output LED3,
 	output LED4,
-	output LED5
+
+	output AA, AB, AC, AD,
+	output AE, AF, AG, CA
 );
 
-	localparam BITS = 5;
+	localparam BITS = 8;
 	localparam LOG2DELAY = 22;
 
 	reg [BITS+LOG2DELAY-1:0] counter = 0;
 	reg [BITS-1:0] outcnt;
 
 	always @(posedge clk) begin
-		counter <= counter + EN;
+		counter <= counter + SW1 + SW2 + 1;
 		outcnt <= counter >> LOG2DELAY;
 	end
 
-	assign {LED1, LED2, LED3, LED4, LED5} = outcnt ^ (outcnt >> 1);
+	assign {LED1, LED2, LED3, LED4} = outcnt ^ (outcnt >> 1);
+
+	// assign CA = counter[10];
+	// seg7enc seg7encinst (
+	// 	.seg({AA, AB, AC, AD, AE, AF, AG}),
+	// 	.dat(CA ? outcnt[3:0] : outcnt[7:4])
+	// );
+
+	assign {AA, AB, AC, AD, AE, AF, AG} = ~(7'b 100_0000 >> outcnt[6:4]);
+	assign CA = outcnt[7];
+endmodule
+
+module seg7enc (
+	input [3:0] dat,
+	output [6:0] seg
+);
+	reg [6:0] seg_inv;
+	always @* begin
+		seg_inv = 0;
+		case (dat)
+			4'h0: seg_inv = 7'b 0111111;
+			4'h1: seg_inv = 7'b 0000110;
+			4'h2: seg_inv = 7'b 1011011;
+			4'h3: seg_inv = 7'b 1001111;
+			4'h4: seg_inv = 7'b 1100110;
+			4'h5: seg_inv = 7'b 1101101;
+			4'h6: seg_inv = 7'b 1111101;
+			4'h7: seg_inv = 7'b 0000111;
+			4'h8: seg_inv = 7'b 1111111;
+			4'h9: seg_inv = 7'b 1101111;
+			4'hA: seg_inv = 7'b 1110111;
+			4'hB: seg_inv = 7'b 1111100;
+			4'hC: seg_inv = 7'b 0111001;
+			4'hD: seg_inv = 7'b 1011110;
+			4'hE: seg_inv = 7'b 1111001;
+			4'hF: seg_inv = 7'b 1110001;
+		endcase
+	end
+	assign seg = ~seg_inv;
 endmodule
diff --git a/examples/igloo2/libero.tcl b/examples/igloo2/libero.tcl
index 1f3476316..abc94e479 100644
--- a/examples/igloo2/libero.tcl
+++ b/examples/igloo2/libero.tcl
@@ -8,13 +8,14 @@ new_project \
     -block_mode 0 \
     -hdl "VERILOG" \
     -family IGLOO2 \
-    -die PA4MGL500 \
-    -package tq144 \
+    -die PA4MGL2500 \
+    -package vf256 \
     -speed -1
 
 import_files -hdl_source {netlist.vm}
 import_files -sdc {example.sdc}
 import_files -io_pdc {example.pdc}
+build_design_hierarchy
 set_option -synth 0
 
 organize_tool_files -tool PLACEROUTE \
@@ -32,22 +33,25 @@ configure_tool -name PLACEROUTE \
     -params EFFORT_LEVEL:false \
     -params REPAIR_MIN_DELAY:false
 
+puts ""
 puts "**> COMPILE"
 run_tool -name {COMPILE}
 puts "<** COMPILE"
 
+puts ""
 puts "**> PLACEROUTE"
 run_tool -name {PLACEROUTE}
 puts "<** PLACEROUTE"
 
+puts ""
 puts "**> VERIFYTIMING"
 run_tool -name {VERIFYTIMING}
 puts "<** VERIFYTIMING"
 
-save_project
-
-# puts "**> export_bitstream"
-# export_bitstream_file -trusted_facility_file 1 -trusted_facility_file_components {FABRIC}
-# puts "<** export_bitstream"
+puts ""
+puts "**> BITSTREAM"
+export_bitstream_file -trusted_facility_file 1 -trusted_facility_file_components {FABRIC}
+puts "<** BITSTREAM"
 
+puts ""
 exit 0
diff --git a/examples/igloo2/runme.sh b/examples/igloo2/runme.sh
index 54247759f..a08894e0a 100644
--- a/examples/igloo2/runme.sh
+++ b/examples/igloo2/runme.sh
@@ -1,4 +1,6 @@
 #!/bin/bash
 set -ex
 yosys -p 'synth_sf2 -top example -edif netlist.edn -vlog netlist.vm' example.v
-LM_LICENSE_FILE=1702@`hostname` /opt/microsemi/Libero_SoC_v11.9/Libero/bin/libero SCRIPT:libero.tcl
+export LM_LICENSE_FILE=${LM_LICENSE_FILE:-1702@localhost}
+/opt/microsemi/Libero_SoC_v12.0/Libero/bin/libero SCRIPT:libero.tcl
+cp proj/designer/example/export/example.stp .
diff --git a/frontends/aiger/aigerparse.h b/frontends/aiger/aigerparse.h
index 42c87a298..39757545f 100644
--- a/frontends/aiger/aigerparse.h
+++ b/frontends/aiger/aigerparse.h
@@ -2,6 +2,7 @@
  *  yosys -- Yosys Open SYnthesis Suite
  *
  *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *                      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
diff --git a/frontends/ast/ast.cc b/frontends/ast/ast.cc
index 5a1bae7a7..d48996167 100644
--- a/frontends/ast/ast.cc
+++ b/frontends/ast/ast.cc
@@ -45,7 +45,7 @@ namespace AST {
 
 // instantiate global variables (private API)
 namespace AST_INTERNAL {
-	bool flag_dump_ast1, flag_dump_ast2, flag_no_dump_ptr, flag_dump_vlog, flag_dump_rtlil, flag_nolatches, flag_nomeminit;
+	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_lib, flag_noopt, flag_icells, flag_autowire;
 	AstNode *current_ast, *current_ast_mod;
 	std::map<std::string, AstNode*> current_scope;
@@ -431,9 +431,12 @@ void AstNode::dumpVlog(FILE *f, std::string indent) const
 		break;
 
 	case AST_RANGE:
-		if (range_valid)
-			fprintf(f, "[%d:%d]", range_left, range_right);
-		else {
+		if (range_valid) {
+			if (range_swapped)
+				fprintf(f, "[%d:%d]", range_right, range_left);
+			else
+				fprintf(f, "[%d:%d]", range_left, range_right);
+		} else {
 			for (auto child : children) {
 				fprintf(f, "%c", first ? '[' : ':');
 				child->dumpVlog(f, "");
@@ -562,7 +565,8 @@ void AstNode::dumpVlog(FILE *f, std::string indent) const
 
 	case AST_CONCAT:
 		fprintf(f, "{");
-		for (auto child : children) {
+		for (int i = GetSize(children)-1; i >= 0; i--) {
+			auto child = children[i];
 			if (!first)
 				fprintf(f, ", ");
 			child->dumpVlog(f, "");
@@ -926,23 +930,28 @@ static AstModule* process_module(AstNode *ast, bool defer, AstNode *original_ast
 		ast_before_simplify = ast->clone();
 
 	if (flag_dump_ast1) {
-		log("Dumping Verilog AST before simplification:\n");
+		log("Dumping AST before simplification:\n");
 		ast->dumpAst(NULL, "    ");
 		log("--- END OF AST DUMP ---\n");
 	}
+	if (flag_dump_vlog1) {
+		log("Dumping Verilog AST before simplification:\n");
+		ast->dumpVlog(NULL, "    ");
+		log("--- END OF AST DUMP ---\n");
+	}
 
 	if (!defer)
 	{
 		while (ast->simplify(!flag_noopt, false, false, 0, -1, false, false)) { }
 
 		if (flag_dump_ast2) {
-			log("Dumping Verilog AST after simplification:\n");
+			log("Dumping AST after simplification:\n");
 			ast->dumpAst(NULL, "    ");
 			log("--- END OF AST DUMP ---\n");
 		}
 
-		if (flag_dump_vlog) {
-			log("Dumping Verilog AST (as requested by dump_vlog option):\n");
+		if (flag_dump_vlog2) {
+			log("Dumping Verilog AST after simplification:\n");
 			ast->dumpVlog(NULL, "    ");
 			log("--- END OF AST DUMP ---\n");
 		}
@@ -1016,14 +1025,15 @@ 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_vlog, bool dump_rtlil,
+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 lib, bool noopt, bool icells, bool nooverwrite, bool overwrite, bool defer, bool autowire)
 {
 	current_ast = ast;
 	flag_dump_ast1 = dump_ast1;
 	flag_dump_ast2 = dump_ast2;
 	flag_no_dump_ptr = no_dump_ptr;
-	flag_dump_vlog = dump_vlog;
+	flag_dump_vlog1 = dump_vlog1;
+	flag_dump_vlog2 = dump_vlog2;
 	flag_dump_rtlil = dump_rtlil;
 	flag_nolatches = nolatches;
 	flag_nomeminit = nomeminit;
@@ -1357,7 +1367,8 @@ std::string AstModule::derive_common(RTLIL::Design *design, dict<RTLIL::IdString
 	current_ast = NULL;
 	flag_dump_ast1 = false;
 	flag_dump_ast2 = false;
-	flag_dump_vlog = false;
+	flag_dump_vlog1 = false;
+	flag_dump_vlog2 = false;
 	flag_nolatches = nolatches;
 	flag_nomeminit = nomeminit;
 	flag_nomem2reg = nomem2reg;
diff --git a/frontends/ast/ast.h b/frontends/ast/ast.h
index 08f91c9c3..ddd59d4be 100644
--- a/frontends/ast/ast.h
+++ b/frontends/ast/ast.h
@@ -214,6 +214,8 @@ namespace AST
 			MEM2REG_FL_SET_ASYNC = 0x00000800,
 			MEM2REG_FL_EQ2       = 0x00001000,
 			MEM2REG_FL_CMPLX_LHS = 0x00002000,
+			MEM2REG_FL_CONST_LHS = 0x00004000,
+			MEM2REG_FL_VAR_LHS   = 0x00008000,
 
 			/* proc flags */
 			MEM2REG_FL_EQ1       = 0x01000000,
@@ -237,6 +239,7 @@ namespace AST
 		bool has_const_only_constructs(bool &recommend_const_eval);
 		void replace_variables(std::map<std::string, varinfo_t> &variables, AstNode *fcall);
 		AstNode *eval_const_function(AstNode *fcall);
+		bool is_simple_const_expr();
 
 		// create a human-readable text representation of the AST (for debugging)
 		void dumpAst(FILE *f, std::string indent) const;
@@ -279,7 +282,7 @@ 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_vlog, bool dump_rtlil, bool nolatches, bool nomeminit,
+	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 lib, bool noopt, bool icells, bool nooverwrite, bool overwrite, bool defer, bool autowire);
 
 	// parametric modules are supported directly by the AST library
diff --git a/frontends/ast/genrtlil.cc b/frontends/ast/genrtlil.cc
index 2d591b29d..b3a2a84be 100644
--- a/frontends/ast/genrtlil.cc
+++ b/frontends/ast/genrtlil.cc
@@ -525,7 +525,16 @@ struct AST_INTERNAL::ProcessGenerator
 				}
 
 				if (last_generated_case != NULL && ast->get_bool_attribute("\\full_case") && default_case == NULL) {
+			#if 0
+					// this is a valid transformation, but as optimization it is premature.
+					// better: add a default case that assigns 'x' to everything, and let later
+					// optimizations take care of the rest
 					last_generated_case->compare.clear();
+			#else
+					default_case = new RTLIL::CaseRule;
+					addChunkActions(default_case->actions, this_case_eq_ltemp, SigSpec(State::Sx, GetSize(this_case_eq_rvalue)));
+					sw->cases.push_back(default_case);
+			#endif
 				} else {
 					if (default_case == NULL) {
 						default_case = new RTLIL::CaseRule;
@@ -544,7 +553,11 @@ struct AST_INTERNAL::ProcessGenerator
 			break;
 
 		case AST_WIRE:
-			log_file_error(ast->filename, ast->linenum, "Found wire declaration in block without label!\n");
+			log_file_error(ast->filename, ast->linenum, "Found reg declaration in block without label!\n");
+			break;
+
+		case AST_ASSIGN:
+			log_file_error(ast->filename, ast->linenum, "Found continous assignment in always/initial block!\n");
 			break;
 
 		case AST_PARAMETER:
@@ -1409,10 +1422,16 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
 			if (GetSize(en) != 1)
 				en = current_module->ReduceBool(NEW_ID, en);
 
-			std::stringstream sstr;
-			sstr << celltype << "$" << filename << ":" << linenum << "$" << (autoidx++);
+			IdString cellname;
+			if (str.empty()) {
+				std::stringstream sstr;
+				sstr << celltype << "$" << filename << ":" << linenum << "$" << (autoidx++);
+				cellname = sstr.str();
+			} else {
+				cellname = str;
+			}
 
-			RTLIL::Cell *cell = current_module->addCell(sstr.str(), celltype);
+			RTLIL::Cell *cell = current_module->addCell(cellname, celltype);
 			cell->attributes["\\src"] = stringf("%s:%d", filename.c_str(), linenum);
 
 			for (auto &attr : attributes) {
diff --git a/frontends/ast/simplify.cc b/frontends/ast/simplify.cc
index 46013544b..63b71b800 100644
--- a/frontends/ast/simplify.cc
+++ b/frontends/ast/simplify.cc
@@ -50,7 +50,6 @@ using namespace AST_INTERNAL;
 bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage, int width_hint, bool sign_hint, bool in_param)
 {
 	static int recursion_counter = 0;
-	static pair<string, int> last_blocking_assignment_warn;
 	static bool deep_recursion_warning = false;
 
 	if (recursion_counter++ == 1000 && deep_recursion_warning) {
@@ -72,7 +71,6 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
 	if (stage == 0)
 	{
 		log_assert(type == AST_MODULE || type == AST_INTERFACE);
-		last_blocking_assignment_warn = pair<string, int>();
 
 		deep_recursion_warning = true;
 		while (simplify(const_fold, at_zero, in_lvalue, 1, width_hint, sign_hint, in_param)) { }
@@ -113,6 +111,9 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
 				if (memflags & AstNode::MEM2REG_FL_CMPLX_LHS)
 					goto verbose_activate;
 
+				if ((memflags & AstNode::MEM2REG_FL_CONST_LHS) && !(memflags & AstNode::MEM2REG_FL_VAR_LHS))
+					goto verbose_activate;
+
 				// log("Note: Not replacing memory %s with list of registers (flags=0x%08lx).\n", mem->str.c_str(), long(memflags));
 				continue;
 
@@ -137,9 +138,15 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
 				int mem_width, mem_size, addr_bits;
 				node->meminfo(mem_width, mem_size, addr_bits);
 
+				int data_range_left = node->children[0]->range_left;
+				int data_range_right = node->children[0]->range_right;
+
+				if (node->children[0]->range_swapped)
+					std::swap(data_range_left, data_range_right);
+
 				for (int i = 0; i < mem_size; i++) {
 					AstNode *reg = new AstNode(AST_WIRE, new AstNode(AST_RANGE,
-							mkconst_int(mem_width-1, true), mkconst_int(0, true)));
+							mkconst_int(data_range_left, true), mkconst_int(data_range_right, true)));
 					reg->str = stringf("%s[%d]", node->str.c_str(), i);
 					reg->is_reg = true;
 					reg->is_signed = node->is_signed;
@@ -325,6 +332,15 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
 		for (size_t i = 0; i < children.size(); i++) {
 			AstNode *node = children[i];
 			if (node->type == AST_WIRE) {
+				if (node->children.size() == 1 && node->children[0]->type == AST_RANGE) {
+					for (auto c : node->children[0]->children) {
+						if (!c->is_simple_const_expr()) {
+							if (attributes.count("\\dynports"))
+								delete attributes.at("\\dynports");
+							attributes["\\dynports"] = AstNode::mkconst_int(1, true);
+						}
+					}
+				}
 				if (this_wire_scope.count(node->str) > 0) {
 					AstNode *first_node = this_wire_scope[node->str];
 					if (first_node->is_input && node->is_reg)
@@ -938,7 +954,7 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
 			}
 		}
 		if (current_scope.count(str) == 0) {
-			if (flag_autowire) {
+			if (flag_autowire || str == "\\$global_clock") {
 				AstNode *auto_wire = new AstNode(AST_AUTOWIRE);
 				auto_wire->str = str;
 				current_ast_mod->children.push_back(auto_wire);
@@ -966,6 +982,9 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage,
 		int data_range_left = id2ast->children[0]->range_left;
 		int data_range_right = id2ast->children[0]->range_right;
 
+		if (id2ast->children[0]->range_swapped)
+			std::swap(data_range_left, data_range_right);
+
 		std::stringstream sstr;
 		sstr << "$mem2bits$" << str << "$" << filename << ":" << linenum << "$" << (autoidx++);
 		std::string wire_id = sstr.str();
@@ -1499,6 +1518,7 @@ skip_dynamic_range_lvalue_expansion:;
 		newNode->children.push_back(assign_en);
 
 		AstNode *assertnode = new AstNode(type);
+		assertnode->str = str;
 		assertnode->children.push_back(new AstNode(AST_IDENTIFIER));
 		assertnode->children.push_back(new AstNode(AST_IDENTIFIER));
 		assertnode->children[0]->str = id_check;
@@ -1579,14 +1599,6 @@ skip_dynamic_range_lvalue_expansion:;
 		sstr << "$memwr$" << children[0]->str << "$" << filename << ":" << linenum << "$" << (autoidx++);
 		std::string id_addr = sstr.str() + "_ADDR", id_data = sstr.str() + "_DATA", id_en = sstr.str() + "_EN";
 
-		if (type == AST_ASSIGN_EQ) {
-			pair<string, int> this_blocking_assignment_warn(filename, linenum);
-			if (this_blocking_assignment_warn != last_blocking_assignment_warn)
-				log_warning("Blocking assignment to memory in line %s:%d is handled like a non-blocking assignment.\n",
-						filename.c_str(), linenum);
-			last_blocking_assignment_warn = this_blocking_assignment_warn;
-		}
-
 		int mem_width, mem_size, addr_bits;
 		bool mem_signed = children[0]->id2ast->is_signed;
 		children[0]->id2ast->meminfo(mem_width, mem_size, addr_bits);
@@ -2169,6 +2181,8 @@ skip_dynamic_range_lvalue_expansion:;
 				}
 
 				newNode = readmem(str == "\\$readmemh", node_filename->bitsAsConst().decode_string(), node_memory->id2ast, start_addr, finish_addr, unconditional_init);
+				delete node_filename;
+				delete node_memory;
 				goto apply_newNode;
 			}
 
@@ -2210,6 +2224,8 @@ skip_dynamic_range_lvalue_expansion:;
 		std::map<std::string, std::string> replace_rules;
 		vector<AstNode*> added_mod_children;
 		dict<std::string, AstNode*> wire_cache;
+		vector<AstNode*> new_stmts;
+		vector<AstNode*> output_assignments;
 
 		if (current_block == NULL)
 		{
@@ -2334,8 +2350,8 @@ skip_dynamic_range_lvalue_expansion:;
 					wire->port_id = 0;
 					wire->is_input = false;
 					wire->is_output = false;
-					if (!child->is_output)
-						wire->attributes["\\nosync"] = AstNode::mkconst_int(1, false);
+					wire->is_reg = true;
+					wire->attributes["\\nosync"] = AstNode::mkconst_int(1, false);
 					wire_cache[child->str] = wire;
 
 					current_ast_mod->children.push_back(wire);
@@ -2357,13 +2373,10 @@ skip_dynamic_range_lvalue_expansion:;
 							new AstNode(AST_ASSIGN_EQ, wire_id, arg) :
 							new AstNode(AST_ASSIGN_EQ, arg, wire_id);
 					assign->children[0]->was_checked = true;
-
-					for (auto it = current_block->children.begin(); it != current_block->children.end(); it++) {
-						if (*it != current_block_child)
-							continue;
-						current_block->children.insert(it, assign);
-						break;
-					}
+					if (child->is_input)
+						new_stmts.push_back(assign);
+					else
+						output_assignments.push_back(assign);
 				}
 			}
 
@@ -2377,14 +2390,18 @@ skip_dynamic_range_lvalue_expansion:;
 			{
 				AstNode *stmt = child->clone();
 				stmt->replace_ids(prefix, replace_rules);
+				new_stmts.push_back(stmt);
+			}
 
-				for (auto it = current_block->children.begin(); it != current_block->children.end(); it++) {
-					if (*it != current_block_child)
-						continue;
-					current_block->children.insert(it, stmt);
-					break;
-				}
+		new_stmts.insert(new_stmts.end(), output_assignments.begin(), output_assignments.end());
+
+		for (auto it = current_block->children.begin(); ; it++) {
+			log_assert(it != current_block->children.end());
+			if (*it == current_block_child) {
+				current_block->children.insert(it, new_stmts.begin(), new_stmts.end());
+				break;
 			}
+		}
 
 	replace_fcall_with_id:
 		if (type == AST_FCALL) {
@@ -2855,7 +2872,11 @@ void AstNode::expand_genblock(std::string index_var, std::string prefix, std::ma
 
 	for (size_t i = 0; i < children.size(); i++) {
 		AstNode *child = children[i];
-		if (child->type != AST_FUNCTION && child->type != AST_TASK && child->type != AST_PREFIX)
+		// AST_PREFIX member names should not be prefixed; a nested AST_PREFIX
+		// still needs to recursed-into
+		if (type == AST_PREFIX && i == 1 && child->type == AST_IDENTIFIER)
+			continue;
+		if (child->type != AST_FUNCTION && child->type != AST_TASK)
 			child->expand_genblock(index_var, prefix, name_map);
 	}
 
@@ -2910,7 +2931,7 @@ void AstNode::mem2reg_as_needed_pass1(dict<AstNode*, pool<std::string>> &mem2reg
 		dict<AstNode*, uint32_t> &mem2reg_candidates, dict<AstNode*, uint32_t> &proc_flags, uint32_t &flags)
 {
 	uint32_t children_flags = 0;
-	int ignore_children_counter = 0;
+	int lhs_children_counter = 0;
 
 	if (type == AST_ASSIGN || type == AST_ASSIGN_LE || type == AST_ASSIGN_EQ)
 	{
@@ -2936,6 +2957,16 @@ void AstNode::mem2reg_as_needed_pass1(dict<AstNode*, pool<std::string>> &mem2reg
 				proc_flags[mem] |= AstNode::MEM2REG_FL_EQ1;
 			}
 
+			// for proper (non-init) writes: remember if this is a constant index or not
+			if ((flags & MEM2REG_FL_INIT) == 0) {
+				if (children[0]->children.size() && children[0]->children[0]->type == AST_RANGE && children[0]->children[0]->children.size()) {
+					if (children[0]->children[0]->children[0]->type == AST_CONSTANT)
+						mem2reg_candidates[mem] |= AstNode::MEM2REG_FL_CONST_LHS;
+					else
+						mem2reg_candidates[mem] |= AstNode::MEM2REG_FL_VAR_LHS;
+				}
+			}
+
 			// remember where this is
 			if (flags & MEM2REG_FL_INIT) {
 				if (!(mem2reg_candidates[mem] & AstNode::MEM2REG_FL_SET_INIT))
@@ -2948,7 +2979,7 @@ void AstNode::mem2reg_as_needed_pass1(dict<AstNode*, pool<std::string>> &mem2reg
 			}
 		}
 
-		ignore_children_counter = 1;
+		lhs_children_counter = 1;
 	}
 
 	if (type == AST_IDENTIFIER && id2ast && id2ast->type == AST_MEMORY)
@@ -2991,12 +3022,23 @@ void AstNode::mem2reg_as_needed_pass1(dict<AstNode*, pool<std::string>> &mem2reg
 	log_assert((flags & ~0x000000ff) == 0);
 
 	for (auto child : children)
-		if (ignore_children_counter > 0)
-			ignore_children_counter--;
-		else if (proc_flags_p)
+	{
+		if (lhs_children_counter > 0) {
+			lhs_children_counter--;
+			if (child->children.size() && child->children[0]->type == AST_RANGE && child->children[0]->children.size()) {
+				for (auto c : child->children[0]->children) {
+					if (proc_flags_p)
+						c->mem2reg_as_needed_pass1(mem2reg_places, mem2reg_candidates, *proc_flags_p, flags);
+					else
+						c->mem2reg_as_needed_pass1(mem2reg_places, mem2reg_candidates, proc_flags, flags);
+				}
+			}
+		} else
+		if (proc_flags_p)
 			child->mem2reg_as_needed_pass1(mem2reg_places, mem2reg_candidates, *proc_flags_p, flags);
 		else
 			child->mem2reg_as_needed_pass1(mem2reg_places, mem2reg_candidates, proc_flags, flags);
+	}
 
 	flags &= ~children_flags | backup_flags;
 
@@ -3048,6 +3090,39 @@ bool AstNode::mem2reg_as_needed_pass2(pool<AstNode*> &mem2reg_set, AstNode *mod,
 	if (type == AST_FUNCTION || type == AST_TASK)
 		return false;
 
+	if (type == AST_MEMINIT && id2ast && mem2reg_set.count(id2ast))
+	{
+		log_assert(children[0]->type == AST_CONSTANT);
+		log_assert(children[1]->type == AST_CONSTANT);
+		log_assert(children[2]->type == AST_CONSTANT);
+
+		int cursor = children[0]->asInt(false);
+		Const data = children[1]->bitsAsConst();
+		int length = children[2]->asInt(false);
+
+		if (length != 0)
+		{
+			AstNode *block = new AstNode(AST_INITIAL, new AstNode(AST_BLOCK));
+			mod->children.push_back(block);
+			block = block->children[0];
+
+			int wordsz = GetSize(data) / length;
+
+			for (int i = 0; i < length; i++) {
+				block->children.push_back(new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER, new AstNode(AST_RANGE, AstNode::mkconst_int(cursor+i, false))), mkconst_bits(data.extract(i*wordsz, wordsz).bits, false)));
+				block->children.back()->children[0]->str = str;
+				block->children.back()->children[0]->id2ast = id2ast;
+				block->children.back()->children[0]->was_checked = true;
+			}
+		}
+
+		AstNode *newNode = new AstNode(AST_NONE);
+		newNode->cloneInto(this);
+		delete newNode;
+
+		did_something = true;
+	}
+
 	if (type == AST_ASSIGN && block == NULL && children[0]->mem2reg_check(mem2reg_set))
 	{
 		if (async_block == NULL) {
@@ -3277,6 +3352,16 @@ bool AstNode::has_const_only_constructs(bool &recommend_const_eval)
 	return false;
 }
 
+bool AstNode::is_simple_const_expr()
+{
+	if (type == AST_IDENTIFIER)
+		return false;
+	for (auto child : children)
+		if (!child->is_simple_const_expr())
+			return false;
+	return true;
+}
+
 // helper function for AstNode::eval_const_function()
 void AstNode::replace_variables(std::map<std::string, AstNode::varinfo_t> &variables, AstNode *fcall)
 {
diff --git a/frontends/ilang/ilang_frontend.cc b/frontends/ilang/ilang_frontend.cc
index 6b302a796..30d9ff79d 100644
--- a/frontends/ilang/ilang_frontend.cc
+++ b/frontends/ilang/ilang_frontend.cc
@@ -47,16 +47,20 @@ struct IlangFrontend : public Frontend {
 		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 blackbox\n");
-		log("        module, and overwrite the existing module if it is  a blackbox module.)\n");
+		log("        module, and overwrite the existing module if it is a blackbox module.)\n");
 		log("\n");
 		log("    -overwrite\n");
 		log("        overwrite existing modules with the same name\n");
 		log("\n");
+		log("    -lib\n");
+		log("        only create empty blackbox modules\n");
+		log("\n");
 	}
 	void execute(std::istream *&f, std::string filename, std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
 	{
 		ILANG_FRONTEND::flag_nooverwrite = false;
 		ILANG_FRONTEND::flag_overwrite = false;
+		ILANG_FRONTEND::flag_lib = false;
 
 		log_header(design, "Executing ILANG frontend.\n");
 
@@ -73,6 +77,10 @@ struct IlangFrontend : public Frontend {
 				ILANG_FRONTEND::flag_overwrite = true;
 				continue;
 			}
+			if (arg == "-lib") {
+				ILANG_FRONTEND::flag_lib = true;
+				continue;
+			}
 			break;
 		}
 		extra_args(f, filename, args, argidx);
diff --git a/frontends/ilang/ilang_frontend.h b/frontends/ilang/ilang_frontend.h
index 052dd4cb2..f8a152841 100644
--- a/frontends/ilang/ilang_frontend.h
+++ b/frontends/ilang/ilang_frontend.h
@@ -34,6 +34,7 @@ namespace ILANG_FRONTEND {
 	extern RTLIL::Design *current_design;
 	extern bool flag_nooverwrite;
 	extern bool flag_overwrite;
+	extern bool flag_lib;
 }
 
 YOSYS_NAMESPACE_END
diff --git a/frontends/ilang/ilang_parser.y b/frontends/ilang/ilang_parser.y
index 5bcc01f42..f83824088 100644
--- a/frontends/ilang/ilang_parser.y
+++ b/frontends/ilang/ilang_parser.y
@@ -37,7 +37,7 @@ namespace ILANG_FRONTEND {
 	std::vector<std::vector<RTLIL::SwitchRule*>*> switch_stack;
 	std::vector<RTLIL::CaseRule*> case_stack;
 	dict<RTLIL::IdString, RTLIL::Const> attrbuf;
-	bool flag_nooverwrite, flag_overwrite;
+	bool flag_nooverwrite, flag_overwrite, flag_lib;
 	bool delete_current_module;
 }
 using namespace ILANG_FRONTEND;
@@ -98,7 +98,7 @@ module:
 		delete_current_module = false;
 		if (current_design->has($2)) {
 			RTLIL::Module *existing_mod = current_design->module($2);
-			if (!flag_overwrite && attrbuf.count("\\blackbox") && attrbuf.at("\\blackbox").as_bool()) {
+			if (!flag_overwrite && (flag_lib || (attrbuf.count("\\blackbox") && attrbuf.at("\\blackbox").as_bool()))) {
 				log("Ignoring blackbox re-definition of module %s.\n", $2);
 				delete_current_module = true;
 			} else if (!flag_nooverwrite && !flag_overwrite && !existing_mod->get_bool_attribute("\\blackbox")) {
@@ -124,6 +124,8 @@ module:
 		current_module->fixup_ports();
 		if (delete_current_module)
 			delete current_module;
+		else if (flag_lib)
+			current_module->makeblackbox();
 		current_module = nullptr;
 	} EOL;
 
diff --git a/frontends/verific/README b/frontends/verific/README
index c76cdd637..89584f2e8 100644
--- a/frontends/verific/README
+++ b/frontends/verific/README
@@ -21,7 +21,7 @@ Then run in the following command in this directory:
 
 	sby -f example.sby
 
-This will generate approximately one page of text outpout. The last lines
+This will generate approximately one page of text output. The last lines
 should be something like this:
 
 	SBY [example] summary: Elapsed clock time [H:MM:SS (secs)]: 0:00:00 (0)
diff --git a/frontends/verific/verific.cc b/frontends/verific/verific.cc
index 8ee951d20..ed9727b88 100644
--- a/frontends/verific/verific.cc
+++ b/frontends/verific/verific.cc
@@ -1619,30 +1619,35 @@ struct VerificExtNets
 	int portname_cnt = 0;
 
 	// a map from Net to the same Net one level up in the design hierarchy
-	std::map<Net*, Net*> net_level_up;
+	std::map<Net*, Net*> net_level_up_drive_up;
+	std::map<Net*, Net*> net_level_up_drive_down;
 
-	Net *get_net_level_up(Net *net)
+	Net *route_up(Net *net, bool drive_up, Net *final_net = nullptr)
 	{
+		auto &net_level_up = drive_up ? net_level_up_drive_up : net_level_up_drive_down;
+
 		if (net_level_up.count(net) == 0)
 		{
 			Netlist *nl = net->Owner();
 
 			// Simply return if Netlist is not unique
-			if (nl->NumOfRefs() != 1)
-				return net;
+			log_assert(nl->NumOfRefs() == 1);
 
 			Instance *up_inst = (Instance*)nl->GetReferences()->GetLast();
 			Netlist *up_nl = up_inst->Owner();
 
 			// create new Port
 			string name = stringf("___extnets_%d", portname_cnt++);
-			Port *new_port = new Port(name.c_str(), DIR_OUT);
+			Port *new_port = new Port(name.c_str(), drive_up ? DIR_OUT : DIR_IN);
 			nl->Add(new_port);
 			net->Connect(new_port);
 
 			// create new Net in up Netlist
-			Net *new_net = new Net(name.c_str());
-			up_nl->Add(new_net);
+			Net *new_net = final_net;
+			if (new_net == nullptr || new_net->Owner() != up_nl) {
+				new_net = new Net(name.c_str());
+				up_nl->Add(new_net);
+			}
 			up_inst->Connect(new_port, new_net);
 
 			net_level_up[net] = new_net;
@@ -1651,6 +1656,39 @@ struct VerificExtNets
 		return net_level_up.at(net);
 	}
 
+	Net *route_up(Net *net, bool drive_up, Netlist *dest, Net *final_net = nullptr)
+	{
+		while (net->Owner() != dest)
+			net = route_up(net, drive_up, final_net);
+		if (final_net != nullptr)
+			log_assert(net == final_net);
+		return net;
+	}
+
+	Netlist *find_common_ancestor(Netlist *A, Netlist *B)
+	{
+		std::set<Netlist*> ancestors_of_A;
+
+		Netlist *cursor = A;
+		while (1) {
+			ancestors_of_A.insert(cursor);
+			if (cursor->NumOfRefs() != 1)
+				break;
+			cursor = ((Instance*)cursor->GetReferences()->GetLast())->Owner();
+		}
+
+		cursor = B;
+		while (1) {
+			if (ancestors_of_A.count(cursor))
+				return cursor;
+			if (cursor->NumOfRefs() != 1)
+				break;
+			cursor = ((Instance*)cursor->GetReferences()->GetLast())->Owner();
+		}
+
+		log_error("No common ancestor found between %s and %s.\n", get_full_netlist_name(A).c_str(), get_full_netlist_name(B).c_str());
+	}
+
 	void run(Netlist *nl)
 	{
 		MapIter mi, mi2;
@@ -1674,19 +1712,37 @@ struct VerificExtNets
 			if (verific_verbose)
 				log("Fixing external net reference on port %s.%s.%s:\n", get_full_netlist_name(nl).c_str(), inst->Name(), port->Name());
 
-			while (net->IsExternalTo(nl))
-			{
-				Net *newnet = get_net_level_up(net);
-				if (newnet == net) break;
+			Netlist *ext_nl = net->Owner();
+
+			if (verific_verbose)
+				log(" external net owner: %s\n", get_full_netlist_name(ext_nl).c_str());
 
+			Netlist *ca_nl = find_common_ancestor(nl, ext_nl);
+
+			if (verific_verbose)
+				log(" common ancestor: %s\n", get_full_netlist_name(ca_nl).c_str());
+
+			Net *ca_net = route_up(net, !port->IsOutput(), ca_nl);
+			Net *new_net = ca_net;
+
+			if (ca_nl != nl)
+			{
 				if (verific_verbose)
-					log("  external net: %s.%s\n", get_full_netlist_name(net->Owner()).c_str(), net->Name());
-				net = newnet;
+					log(" net in common ancestor: %s\n", ca_net->Name());
+
+				string name = stringf("___extnets_%d", portname_cnt++);
+				new_net = new Net(name.c_str());
+				nl->Add(new_net);
+
+				Net *n = route_up(new_net, port->IsOutput(), ca_nl, ca_net);
+				log_assert(n == ca_net);
 			}
 
 			if (verific_verbose)
-				log("  final net: %s.%s%s\n", get_full_netlist_name(net->Owner()).c_str(), net->Name(), net->IsExternalTo(nl) ? " (external)" : "");
-			todo_connect.push_back(tuple<Instance*, Port*, Net*>(inst, port, net));
+				log(" new local net: %s\n", new_net->Name());
+
+			log_assert(!new_net->IsExternalTo(nl));
+			todo_connect.push_back(tuple<Instance*, Port*, Net*>(inst, port, new_net));
 		}
 
 		for (auto it : todo_connect) {
@@ -1855,6 +1911,13 @@ struct VerificPass : public Pass {
 		log("  -autocover\n");
 		log("    Generate automatic cover statements for all asserts\n");
 		log("\n");
+		log("  -chparam name value \n");
+		log("    Elaborate the specified top modules (all modules when -all given) using\n");
+		log("    this parameter value. Modules on which this parameter does not exist will\n");
+		log("    cause Verific to produce a VERI-1928 or VHDL-1676 message. This option\n");
+		log("    can be specified multiple times to override multiple parameters.\n");
+		log("    String values must be passed in double quotes (\").\n");
+		log("\n");
 		log("  -v, -vv\n");
 		log("    Verbose log messages. (-vv is even more verbose than -v.)\n");
 		log("\n");
@@ -2109,6 +2172,7 @@ struct VerificPass : public Pass {
 			bool mode_autocover = false;
 			bool flatten = false, extnets = false;
 			string dumpfile;
+			Map parameters(STRING_HASH);
 
 			for (argidx++; argidx < GetSize(args); argidx++) {
 				if (args[argidx] == "-all") {
@@ -2147,6 +2211,15 @@ struct VerificPass : public Pass {
 					mode_autocover = true;
 					continue;
 				}
+				if (args[argidx] == "-chparam"  && argidx+2 < GetSize(args)) {
+                                        const std::string &key = args[++argidx];
+                                        const std::string &value = args[++argidx];
+					unsigned new_insertion = parameters.Insert(key.c_str(), value.c_str(),
+									           1 /* force_overwrite */);
+					if (!new_insertion)
+						log_warning_noprefix("-chparam %s already specified: overwriting.\n", key.c_str());
+					continue;
+				}
 				if (args[argidx] == "-V") {
 					mode_verific = true;
 					continue;
@@ -2180,7 +2253,7 @@ struct VerificPass : public Pass {
 				if (vhdl_lib) vhdl_libs.InsertLast(vhdl_lib);
 				if (veri_lib) veri_libs.InsertLast(veri_lib);
 
-				Array *netlists = hier_tree::ElaborateAll(&veri_libs, &vhdl_libs);
+				Array *netlists = hier_tree::ElaborateAll(&veri_libs, &vhdl_libs, &parameters);
 				Netlist *nl;
 				int i;
 
@@ -2217,7 +2290,7 @@ struct VerificPass : public Pass {
 				}
 
 				log("Running hier_tree::Elaborate().\n");
-				Array *netlists = hier_tree::Elaborate(&veri_modules, &vhdl_units);
+				Array *netlists = hier_tree::Elaborate(&veri_modules, &vhdl_units, &parameters);
 				Netlist *nl;
 				int i;
 
@@ -2313,21 +2386,43 @@ struct ReadPass : public Pass {
 		log("\n");
 		log("Add directory to global Verilog/SystemVerilog include directories.\n");
 		log("\n");
+		log("\n");
+		log("    read -verific\n");
+		log("    read -noverific\n");
+		log("\n");
+		log("Subsequent calls to 'read' will either use or not use Verific. Calling 'read'\n");
+		log("with -verific will result in an error on Yosys binaries that are built without\n");
+		log("Verific support. The default is to use Verific if it is available.\n");
+		log("\n");
 	}
 	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
 	{
-		if (args.size() < 2)
+#ifdef YOSYS_ENABLE_VERIFIC
+		static bool verific_available = !check_noverific_env();
+#else
+		static bool verific_available = false;
+#endif
+		static bool use_verific = verific_available;
+
+		if (args.size() < 2 || args[1][0] != '-')
 			log_cmd_error("Missing mode parameter.\n");
 
+		if (args[1] == "-verific" || args[1] == "-noverific") {
+			if (args.size() != 2)
+				log_cmd_error("Additional arguments to -verific/-noverific.\n");
+			if (args[1] == "-verific") {
+				if (!verific_available)
+					log_cmd_error("This version of Yosys is built without Verific support.\n");
+				use_verific = true;
+			} else {
+				use_verific = false;
+			}
+			return;
+		}
+
 		if (args.size() < 3)
 			log_cmd_error("Missing file name parameter.\n");
 
-#ifdef YOSYS_ENABLE_VERIFIC
-		bool use_verific = !check_noverific_env();
-#else
-		bool use_verific = false;
-#endif
-
 		if (args[1] == "-vlog95" || args[1] == "-vlog2k") {
 			if (use_verific) {
 				args[0] = "verific";
diff --git a/frontends/verific/verificsva.cc b/frontends/verific/verificsva.cc
index 6681115df..8ea8372d3 100644
--- a/frontends/verific/verificsva.cc
+++ b/frontends/verific/verificsva.cc
@@ -1666,7 +1666,20 @@ struct VerificSvaImporter
 				log("  importing SVA property at root cell %s (%s) at %s:%d.\n", root->Name(), root->View()->Owner()->Name(),
 						LineFile::GetFileName(root->Linefile()), LineFile::GetLineNo(root->Linefile()));
 
-			RTLIL::IdString root_name = module->uniquify(importer->mode_names || root->IsUserDeclared() ? RTLIL::escape_id(root->Name()) : NEW_ID);
+			bool is_user_declared = root->IsUserDeclared();
+
+			// FIXME
+			if (!is_user_declared) {
+				const char *name = root->Name();
+				for (int i = 0; name[i]; i++) {
+					if (i ? (name[i] < '0' || name[i] > '9') : (name[i] != 'i')) {
+						is_user_declared = true;
+						break;
+					}
+				}
+			}
+
+			RTLIL::IdString root_name = module->uniquify(importer->mode_names || is_user_declared ? RTLIL::escape_id(root->Name()) : NEW_ID);
 
 			// parse SVA sequence into trigger signal
 
diff --git a/frontends/verilog/Makefile.inc b/frontends/verilog/Makefile.inc
index dbaace585..0a1f97ac0 100644
--- a/frontends/verilog/Makefile.inc
+++ b/frontends/verilog/Makefile.inc
@@ -14,6 +14,8 @@ frontends/verilog/verilog_lexer.cc: frontends/verilog/verilog_lexer.l
 	$(Q) mkdir -p $(dir $@)
 	$(P) flex -o frontends/verilog/verilog_lexer.cc $<
 
+frontends/verilog/verilog_parser.tab.o: CXXFLAGS += -DYYMAXDEPTH=100000
+
 OBJS += frontends/verilog/verilog_parser.tab.o
 OBJS += frontends/verilog/verilog_lexer.o
 OBJS += frontends/verilog/preproc.o
diff --git a/frontends/verilog/verilog_frontend.cc b/frontends/verilog/verilog_frontend.cc
index aeea36a2b..504f8b3f3 100644
--- a/frontends/verilog/verilog_frontend.cc
+++ b/frontends/verilog/verilog_frontend.cc
@@ -81,6 +81,9 @@ struct VerilogFrontend : public Frontend {
 		log("    -assert-assumes\n");
 		log("        treat all assume() statements like assert() statements\n");
 		log("\n");
+		log("    -debug\n");
+		log("        alias for -dump_ast1 -dump_ast2 -dump_vlog1 -dump_vlog2 -yydebug\n");
+		log("\n");
 		log("    -dump_ast1\n");
 		log("        dump abstract syntax tree (before simplification)\n");
 		log("\n");
@@ -90,7 +93,10 @@ struct VerilogFrontend : public Frontend {
 		log("    -no_dump_ptr\n");
 		log("        do not include hex memory addresses in dump (easier to diff dumps)\n");
 		log("\n");
-		log("    -dump_vlog\n");
+		log("    -dump_vlog1\n");
+		log("        dump ast as Verilog code (before simplification)\n");
+		log("\n");
+		log("    -dump_vlog2\n");
 		log("        dump ast as Verilog code (after simplification)\n");
 		log("\n");
 		log("    -dump_rtlil\n");
@@ -197,7 +203,8 @@ struct VerilogFrontend : public Frontend {
 		bool flag_dump_ast1 = false;
 		bool flag_dump_ast2 = false;
 		bool flag_no_dump_ptr = false;
-		bool flag_dump_vlog = false;
+		bool flag_dump_vlog1 = false;
+		bool flag_dump_vlog2 = false;
 		bool flag_dump_rtlil = false;
 		bool flag_nolatches = false;
 		bool flag_nomeminit = false;
@@ -258,6 +265,14 @@ struct VerilogFrontend : public Frontend {
 				assert_assumes_mode = true;
 				continue;
 			}
+			if (arg == "-debug") {
+				flag_dump_ast1 = true;
+				flag_dump_ast2 = true;
+				flag_dump_vlog1 = true;
+				flag_dump_vlog2 = true;
+				frontend_verilog_yydebug = true;
+				continue;
+			}
 			if (arg == "-dump_ast1") {
 				flag_dump_ast1 = true;
 				continue;
@@ -270,8 +285,12 @@ struct VerilogFrontend : public Frontend {
 				flag_no_dump_ptr = true;
 				continue;
 			}
-			if (arg == "-dump_vlog") {
-				flag_dump_vlog = true;
+			if (arg == "-dump_vlog1") {
+				flag_dump_vlog1 = true;
+				continue;
+			}
+			if (arg == "-dump_vlog2") {
+				flag_dump_vlog2 = true;
 				continue;
 			}
 			if (arg == "-dump_rtlil") {
@@ -410,7 +429,7 @@ struct VerilogFrontend : public Frontend {
 		if (flag_nodpi)
 			error_on_dpi_function(current_ast);
 
-		AST::process(design, current_ast, flag_dump_ast1, flag_dump_ast2, flag_no_dump_ptr, flag_dump_vlog, flag_dump_rtlil, flag_nolatches, flag_nomeminit, flag_nomem2reg, flag_mem2reg, lib_mode, flag_noopt, flag_icells, flag_nooverwrite, flag_overwrite, flag_defer, default_nettype_wire);
+		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, lib_mode, flag_noopt, flag_icells, 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 1b1873e24..6ef38252a 100644
--- a/frontends/verilog/verilog_lexer.l
+++ b/frontends/verilog/verilog_lexer.l
@@ -189,6 +189,14 @@ YOSYS_NAMESPACE_END
 "always_ff"    { SV_KEYWORD(TOK_ALWAYS); }
 "always_latch" { SV_KEYWORD(TOK_ALWAYS); }
 
+ /* use special token for labels on assert, assume, cover, and restrict because it's insanley complex
+    to fix parsing of cells otherwise. (the current cell parser forces a reduce very early to update some
+    global state.. its a mess) */
+[a-zA-Z_$][a-zA-Z0-9_$]*/[ \t\r\n]*:[ \t\r\n]*(assert|assume|cover|restrict)[^a-zA-Z0-9_$\.] {
+	frontend_verilog_yylval.string = new std::string(std::string("\\") + yytext);
+	return TOK_SVA_LABEL;
+}
+
 "assert"     { if (formal_mode) return TOK_ASSERT; SV_KEYWORD(TOK_ASSERT); }
 "assume"     { if (formal_mode) return TOK_ASSUME; SV_KEYWORD(TOK_ASSUME); }
 "cover"      { if (formal_mode) return TOK_COVER; SV_KEYWORD(TOK_COVER); }
@@ -303,7 +311,7 @@ supply1 { return TOK_SUPPLY1; }
 
 [a-zA-Z_$][a-zA-Z0-9_$\.]* {
 	frontend_verilog_yylval.string = new std::string(std::string("\\") + yytext);
-    return TOK_ID;
+	return TOK_ID;
 }
 
 "/*"[ \t]*(synopsys|synthesis)[ \t]*translate_off[ \t]*"*/" {
diff --git a/frontends/verilog/verilog_parser.y b/frontends/verilog/verilog_parser.y
index a6718b020..52685f637 100644
--- a/frontends/verilog/verilog_parser.y
+++ b/frontends/verilog/verilog_parser.y
@@ -105,7 +105,8 @@ static void free_attr(std::map<std::string, AstNode*> *al)
 	bool boolean;
 }
 
-%token <string> TOK_STRING TOK_ID TOK_CONSTVAL TOK_REALVAL TOK_PRIMITIVE
+%token <string> TOK_STRING TOK_ID TOK_CONSTVAL TOK_REALVAL TOK_PRIMITIVE TOK_SVA_LABEL
+%token TOK_ASSERT TOK_ASSUME TOK_RESTRICT TOK_COVER
 %token ATTR_BEGIN ATTR_END DEFATTR_BEGIN DEFATTR_END
 %token TOK_MODULE TOK_ENDMODULE TOK_PARAMETER TOK_LOCALPARAM TOK_DEFPARAM
 %token TOK_PACKAGE TOK_ENDPACKAGE TOK_PACKAGESEP
@@ -119,14 +120,13 @@ static void free_attr(std::map<std::string, AstNode*> *al)
 %token TOK_GENERATE TOK_ENDGENERATE TOK_GENVAR TOK_REAL
 %token TOK_SYNOPSYS_FULL_CASE TOK_SYNOPSYS_PARALLEL_CASE
 %token TOK_SUPPLY0 TOK_SUPPLY1 TOK_TO_SIGNED TOK_TO_UNSIGNED
-%token TOK_POS_INDEXED TOK_NEG_INDEXED TOK_ASSERT TOK_ASSUME
-%token TOK_RESTRICT TOK_COVER TOK_PROPERTY TOK_ENUM TOK_TYPEDEF
+%token TOK_POS_INDEXED TOK_NEG_INDEXED TOK_PROPERTY TOK_ENUM TOK_TYPEDEF
 %token TOK_RAND TOK_CONST TOK_CHECKER TOK_ENDCHECKER TOK_EVENTUALLY
 %token TOK_INCREMENT TOK_DECREMENT TOK_UNIQUE TOK_PRIORITY
 
 %type <ast> range range_or_multirange  non_opt_range non_opt_multirange range_or_signed_int
 %type <ast> wire_type expr basic_expr concat_list rvalue lvalue lvalue_concat_list
-%type <string> opt_label tok_prim_wrapper hierarchical_id
+%type <string> opt_label opt_sva_label tok_prim_wrapper hierarchical_id
 %type <boolean> opt_signed opt_property unique_case_attr
 %type <al> attr case_attr
 
@@ -1329,6 +1329,14 @@ opt_label:
 		$$ = NULL;
 	};
 
+opt_sva_label:
+	TOK_SVA_LABEL ':' {
+		$$ = $1;
+	} |
+	/* empty */ {
+		$$ = NULL;
+	};
+
 opt_property:
 	TOK_PROPERTY {
 		$$ = true;
@@ -1337,9 +1345,6 @@ opt_property:
 		$$ = false;
 	};
 
-opt_stmt_label:
-	TOK_ID ':' | /* empty */;
-
 modport_stmt:
     TOK_MODPORT TOK_ID {
         AstNode *modport = new AstNode(AST_MODPORT);
@@ -1376,83 +1381,164 @@ modport_type_token:
     TOK_INPUT {current_modport_input = 1; current_modport_output = 0;} | TOK_OUTPUT {current_modport_input = 0; current_modport_output = 1;}
 
 assert:
-	opt_stmt_label TOK_ASSERT opt_property '(' expr ')' ';' {
-		if (noassert_mode)
+	opt_sva_label TOK_ASSERT opt_property '(' expr ')' ';' {
+		if (noassert_mode) {
 			delete $5;
-		else
-			ast_stack.back()->children.push_back(new AstNode(assume_asserts_mode ? AST_ASSUME : AST_ASSERT, $5));
+		} else {
+			AstNode *node = new AstNode(assume_asserts_mode ? AST_ASSUME : AST_ASSERT, $5);
+			if ($1 != nullptr)
+				node->str = *$1;
+			ast_stack.back()->children.push_back(node);
+		}
+		if ($1 != nullptr)
+			delete $1;
 	} |
-	opt_stmt_label TOK_ASSUME opt_property '(' expr ')' ';' {
-		if (noassume_mode)
+	opt_sva_label TOK_ASSUME opt_property '(' expr ')' ';' {
+		if (noassume_mode) {
 			delete $5;
-		else
-			ast_stack.back()->children.push_back(new AstNode(assert_assumes_mode ? AST_ASSERT : AST_ASSUME, $5));
+		} else {
+			AstNode *node = new AstNode(assert_assumes_mode ? AST_ASSERT : AST_ASSUME, $5);
+			if ($1 != nullptr)
+				node->str = *$1;
+			ast_stack.back()->children.push_back(node);
+		}
+		if ($1 != nullptr)
+			delete $1;
 	} |
-	opt_stmt_label TOK_ASSERT opt_property '(' TOK_EVENTUALLY expr ')' ';' {
-		if (noassert_mode)
+	opt_sva_label TOK_ASSERT opt_property '(' TOK_EVENTUALLY expr ')' ';' {
+		if (noassert_mode) {
 			delete $6;
-		else
-			ast_stack.back()->children.push_back(new AstNode(assume_asserts_mode ? AST_FAIR : AST_LIVE, $6));
+		} else {
+			AstNode *node = new AstNode(assume_asserts_mode ? AST_FAIR : AST_LIVE, $6);
+			if ($1 != nullptr)
+				node->str = *$1;
+			ast_stack.back()->children.push_back(node);
+		}
+		if ($1 != nullptr)
+			delete $1;
 	} |
-	opt_stmt_label TOK_ASSUME opt_property '(' TOK_EVENTUALLY expr ')' ';' {
-		if (noassume_mode)
+	opt_sva_label TOK_ASSUME opt_property '(' TOK_EVENTUALLY expr ')' ';' {
+		if (noassume_mode) {
 			delete $6;
-		else
-			ast_stack.back()->children.push_back(new AstNode(assert_assumes_mode ? AST_LIVE : AST_FAIR, $6));
+		} else {
+			AstNode *node = new AstNode(assert_assumes_mode ? AST_LIVE : AST_FAIR, $6);
+			if ($1 != nullptr)
+				node->str = *$1;
+			ast_stack.back()->children.push_back(node);
+		}
+		if ($1 != nullptr)
+			delete $1;
 	} |
-	opt_stmt_label TOK_COVER opt_property '(' expr ')' ';' {
-		ast_stack.back()->children.push_back(new AstNode(AST_COVER, $5));
+	opt_sva_label TOK_COVER opt_property '(' expr ')' ';' {
+		AstNode *node = new AstNode(AST_COVER, $5);
+		if ($1 != nullptr) {
+			node->str = *$1;
+			delete $1;
+		}
+		ast_stack.back()->children.push_back(node);
 	} |
-	opt_stmt_label TOK_COVER opt_property '(' ')' ';' {
-		ast_stack.back()->children.push_back(new AstNode(AST_COVER, AstNode::mkconst_int(1, false)));
+	opt_sva_label TOK_COVER opt_property '(' ')' ';' {
+		AstNode *node = new AstNode(AST_COVER, AstNode::mkconst_int(1, false));
+		if ($1 != nullptr) {
+			node->str = *$1;
+			delete $1;
+		}
+		ast_stack.back()->children.push_back(node);
 	} |
-	opt_stmt_label TOK_COVER ';' {
-		ast_stack.back()->children.push_back(new AstNode(AST_COVER, AstNode::mkconst_int(1, false)));
+	opt_sva_label TOK_COVER ';' {
+		AstNode *node = new AstNode(AST_COVER, AstNode::mkconst_int(1, false));
+		if ($1 != nullptr) {
+			node->str = *$1;
+			delete $1;
+		}
+		ast_stack.back()->children.push_back(node);
 	} |
-	opt_stmt_label TOK_RESTRICT opt_property '(' expr ')' ';' {
-		if (norestrict_mode)
+	opt_sva_label TOK_RESTRICT opt_property '(' expr ')' ';' {
+		if (norestrict_mode) {
 			delete $5;
-		else
-			ast_stack.back()->children.push_back(new AstNode(AST_ASSUME, $5));
+		} else {
+			AstNode *node = new AstNode(AST_ASSUME, $5);
+			if ($1 != nullptr)
+				node->str = *$1;
+			ast_stack.back()->children.push_back(node);
+		}
 		if (!$3)
 			log_file_warning(current_filename, get_line_num(), "SystemVerilog does not allow \"restrict\" without \"property\".\n");
+		if ($1 != nullptr)
+			delete $1;
 	} |
-	opt_stmt_label TOK_RESTRICT opt_property '(' TOK_EVENTUALLY expr ')' ';' {
-		if (norestrict_mode)
+	opt_sva_label TOK_RESTRICT opt_property '(' TOK_EVENTUALLY expr ')' ';' {
+		if (norestrict_mode) {
 			delete $6;
-		else
-			ast_stack.back()->children.push_back(new AstNode(AST_FAIR, $6));
+		} else {
+			AstNode *node = new AstNode(AST_FAIR, $6);
+			if ($1 != nullptr)
+				node->str = *$1;
+			ast_stack.back()->children.push_back(node);
+		}
 		if (!$3)
 			log_file_warning(current_filename, get_line_num(), "SystemVerilog does not allow \"restrict\" without \"property\".\n");
+		if ($1 != nullptr)
+			delete $1;
 	};
 
 assert_property:
-	TOK_ASSERT TOK_PROPERTY '(' expr ')' ';' {
-		ast_stack.back()->children.push_back(new AstNode(assume_asserts_mode ? AST_ASSUME : AST_ASSERT, $4));
-	} |
-	TOK_ASSUME TOK_PROPERTY '(' expr ')' ';' {
-		ast_stack.back()->children.push_back(new AstNode(AST_ASSUME, $4));
+	opt_sva_label TOK_ASSERT TOK_PROPERTY '(' expr ')' ';' {
+		ast_stack.back()->children.push_back(new AstNode(assume_asserts_mode ? AST_ASSUME : AST_ASSERT, $5));
+		if ($1 != nullptr) {
+			ast_stack.back()->children.back()->str = *$1;
+			delete $1;
+		}
 	} |
-	TOK_ASSERT TOK_PROPERTY '(' TOK_EVENTUALLY expr ')' ';' {
-		ast_stack.back()->children.push_back(new AstNode(assume_asserts_mode ? AST_FAIR : AST_LIVE, $5));
+	opt_sva_label TOK_ASSUME TOK_PROPERTY '(' expr ')' ';' {
+		ast_stack.back()->children.push_back(new AstNode(AST_ASSUME, $5));
+		if ($1 != nullptr) {
+			ast_stack.back()->children.back()->str = *$1;
+			delete $1;
+		}
 	} |
-	TOK_ASSUME TOK_PROPERTY '(' TOK_EVENTUALLY expr ')' ';' {
-		ast_stack.back()->children.push_back(new AstNode(AST_FAIR, $5));
+	opt_sva_label TOK_ASSERT TOK_PROPERTY '(' TOK_EVENTUALLY expr ')' ';' {
+		ast_stack.back()->children.push_back(new AstNode(assume_asserts_mode ? AST_FAIR : AST_LIVE, $6));
+		if ($1 != nullptr) {
+			ast_stack.back()->children.back()->str = *$1;
+			delete $1;
+		}
 	} |
-	TOK_COVER TOK_PROPERTY '(' expr ')' ';' {
-		ast_stack.back()->children.push_back(new AstNode(AST_COVER, $4));
+	opt_sva_label TOK_ASSUME TOK_PROPERTY '(' TOK_EVENTUALLY expr ')' ';' {
+		ast_stack.back()->children.push_back(new AstNode(AST_FAIR, $6));
+		if ($1 != nullptr) {
+			ast_stack.back()->children.back()->str = *$1;
+			delete $1;
+		}
 	} |
-	TOK_RESTRICT TOK_PROPERTY '(' expr ')' ';' {
-		if (norestrict_mode)
-			delete $4;
-		else
-			ast_stack.back()->children.push_back(new AstNode(AST_ASSUME, $4));
+	opt_sva_label TOK_COVER TOK_PROPERTY '(' expr ')' ';' {
+		ast_stack.back()->children.push_back(new AstNode(AST_COVER, $5));
+		if ($1 != nullptr) {
+			ast_stack.back()->children.back()->str = *$1;
+			delete $1;
+		}
 	} |
-	TOK_RESTRICT TOK_PROPERTY '(' TOK_EVENTUALLY expr ')' ';' {
-		if (norestrict_mode)
+	opt_sva_label TOK_RESTRICT TOK_PROPERTY '(' expr ')' ';' {
+		if (norestrict_mode) {
 			delete $5;
-		else
-			ast_stack.back()->children.push_back(new AstNode(AST_FAIR, $5));
+		} else {
+			ast_stack.back()->children.push_back(new AstNode(AST_ASSUME, $5));
+			if ($1 != nullptr) {
+				ast_stack.back()->children.back()->str = *$1;
+				delete $1;
+			}
+		}
+	} |
+	opt_sva_label TOK_RESTRICT TOK_PROPERTY '(' TOK_EVENTUALLY expr ')' ';' {
+		if (norestrict_mode) {
+			delete $6;
+		} else {
+			ast_stack.back()->children.push_back(new AstNode(AST_FAIR, $6));
+			if ($1 != nullptr) {
+				ast_stack.back()->children.back()->str = *$1;
+				delete $1;
+			}
+		}
 	};
 
 simple_behavioral_stmt:
@@ -1670,6 +1756,11 @@ case_expr_list:
 	TOK_DEFAULT {
 		ast_stack.back()->children.push_back(new AstNode(AST_DEFAULT));
 	} |
+	TOK_SVA_LABEL {
+		ast_stack.back()->children.push_back(new AstNode(AST_IDENTIFIER));
+		ast_stack.back()->children.back()->str = *$1;
+		delete $1;
+	} |
 	expr {
 		ast_stack.back()->children.push_back($1);
 	} |
diff --git a/kernel/celltypes.h b/kernel/celltypes.h
index 8b8a56111..ae88f4aaf 100644
--- a/kernel/celltypes.h
+++ b/kernel/celltypes.h
@@ -82,6 +82,27 @@ struct CellTypes
 
 	void setup_internals()
 	{
+		setup_internals_eval();
+
+		IdString A = "\\A", B = "\\B", EN = "\\EN", Y = "\\Y";
+
+		setup_type("$tribuf", {A, EN}, {Y}, true);
+
+		setup_type("$assert", {A, EN}, pool<RTLIL::IdString>(), true);
+		setup_type("$assume", {A, EN}, pool<RTLIL::IdString>(), true);
+		setup_type("$live", {A, EN}, pool<RTLIL::IdString>(), true);
+		setup_type("$fair", {A, EN}, pool<RTLIL::IdString>(), true);
+		setup_type("$cover", {A, EN}, pool<RTLIL::IdString>(), true);
+		setup_type("$initstate", pool<RTLIL::IdString>(), {Y}, true);
+		setup_type("$anyconst", pool<RTLIL::IdString>(), {Y}, true);
+		setup_type("$anyseq", pool<RTLIL::IdString>(), {Y}, true);
+		setup_type("$allconst", pool<RTLIL::IdString>(), {Y}, true);
+		setup_type("$allseq", pool<RTLIL::IdString>(), {Y}, true);
+		setup_type("$equiv", {A, B}, {Y}, true);
+	}
+
+	void setup_internals_eval()
+	{
 		std::vector<RTLIL::IdString> unary_ops = {
 			"$not", "$pos", "$neg",
 			"$reduce_and", "$reduce_or", "$reduce_xor", "$reduce_xnor", "$reduce_bool",
@@ -111,20 +132,6 @@ struct CellTypes
 		setup_type("$lcu", {P, G, CI}, {CO}, true);
 		setup_type("$alu", {A, B, CI, BI}, {X, Y, CO}, true);
 		setup_type("$fa", {A, B, C}, {X, Y}, true);
-
-		setup_type("$tribuf", {A, EN}, {Y}, true);
-
-		setup_type("$assert", {A, EN}, pool<RTLIL::IdString>(), true);
-		setup_type("$assume", {A, EN}, pool<RTLIL::IdString>(), true);
-		setup_type("$live", {A, EN}, pool<RTLIL::IdString>(), true);
-		setup_type("$fair", {A, EN}, pool<RTLIL::IdString>(), true);
-		setup_type("$cover", {A, EN}, pool<RTLIL::IdString>(), true);
-		setup_type("$initstate", pool<RTLIL::IdString>(), {Y}, true);
-		setup_type("$anyconst", pool<RTLIL::IdString>(), {Y}, true);
-		setup_type("$anyseq", pool<RTLIL::IdString>(), {Y}, true);
-		setup_type("$allconst", pool<RTLIL::IdString>(), {Y}, true);
-		setup_type("$allseq", pool<RTLIL::IdString>(), {Y}, true);
-		setup_type("$equiv", {A, B}, {Y}, true);
 	}
 
 	void setup_internals_mem()
@@ -154,6 +161,15 @@ struct CellTypes
 
 	void setup_stdcells()
 	{
+		setup_stdcells_eval();
+
+		IdString A = "\\A", E = "\\E", Y = "\\Y";
+
+		setup_type("$_TBUF_", {A, E}, {Y}, true);
+	}
+
+	void setup_stdcells_eval()
+	{
 		IdString A = "\\A", B = "\\B", C = "\\C", D = "\\D";
 		IdString E = "\\E", F = "\\F", G = "\\G", H = "\\H";
 		IdString I = "\\I", J = "\\J", K = "\\K", L = "\\L";
@@ -179,7 +195,6 @@ struct CellTypes
 		setup_type("$_OAI3_", {A, B, C}, {Y}, true);
 		setup_type("$_AOI4_", {A, B, C, D}, {Y}, true);
 		setup_type("$_OAI4_", {A, B, C, D}, {Y}, true);
-		setup_type("$_TBUF_", {A, E}, {Y}, true);
 	}
 
 	void setup_stdcells_mem()
diff --git a/kernel/hashlib.h b/kernel/hashlib.h
index df534ec1b..e7cb312ed 100644
--- a/kernel/hashlib.h
+++ b/kernel/hashlib.h
@@ -557,9 +557,11 @@ public:
 	void clear() { hashtable.clear(); entries.clear(); }
 
 	iterator begin() { return iterator(this, int(entries.size())-1); }
+	iterator element(int n) { return iterator(this, int(entries.size())-1-n); }
 	iterator end() { return iterator(nullptr, -1); }
 
 	const_iterator begin() const { return const_iterator(this, int(entries.size())-1); }
+	const_iterator element(int n) const { return const_iterator(this, int(entries.size())-1-n); }
 	const_iterator end() const { return const_iterator(nullptr, -1); }
 };
 
@@ -881,9 +883,11 @@ public:
 	void clear() { hashtable.clear(); entries.clear(); }
 
 	iterator begin() { return iterator(this, int(entries.size())-1); }
+	iterator element(int n) { return iterator(this, int(entries.size())-1-n); }
 	iterator end() { return iterator(nullptr, -1); }
 
 	const_iterator begin() const { return const_iterator(this, int(entries.size())-1); }
+	const_iterator element(int n) const { return const_iterator(this, int(entries.size())-1-n); }
 	const_iterator end() const { return const_iterator(nullptr, -1); }
 };
 
@@ -952,6 +956,7 @@ public:
 	void clear() { database.clear(); }
 
 	const_iterator begin() const { return database.begin(); }
+	const_iterator element(int n) const { return database.element(n); }
 	const_iterator end() const { return database.end(); }
 };
 
@@ -1051,6 +1056,7 @@ public:
 	void clear() { database.clear(); parents.clear(); }
 
 	const_iterator begin() const { return database.begin(); }
+	const_iterator element(int n) const { return database.element(n); }
 	const_iterator end() const { return database.end(); }
 };
 
diff --git a/kernel/log.cc b/kernel/log.cc
index 0ee2170a0..400a549dd 100644
--- a/kernel/log.cc
+++ b/kernel/log.cc
@@ -196,7 +196,11 @@ void logv_header(RTLIL::Design *design, const char *format, va_list ap)
 	if (log_hdump.count(header_id) && design != nullptr)
 		for (auto &filename : log_hdump.at(header_id)) {
 			log("Dumping current design to '%s'.\n", filename.c_str());
+			if (yosys_xtrace)
+				IdString::xtrace_db_dump();
 			Pass::call(design, {"dump", "-o", filename});
+			if (yosys_xtrace)
+				log("#X# -- end of dump --\n");
 		}
 
 	if (pop_errfile)
diff --git a/kernel/register.cc b/kernel/register.cc
index 402a5b3ea..64956401f 100644
--- a/kernel/register.cc
+++ b/kernel/register.cc
@@ -86,6 +86,8 @@ Pass::pre_post_exec_state_t Pass::pre_execute()
 
 void Pass::post_execute(Pass::pre_post_exec_state_t state)
 {
+	IdString::checkpoint();
+
 	int64_t time_ns = PerformanceTimer::query() - state.begin_ns;
 	runtime_ns += time_ns;
 	current_pass = state.parent_pass;
diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index d4aebcda9..9ae20a317 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -33,6 +33,8 @@ std::vector<int> RTLIL::IdString::global_refcount_storage_;
 std::vector<char*> RTLIL::IdString::global_id_storage_;
 dict<char*, int, hash_cstr_ops> RTLIL::IdString::global_id_index_;
 std::vector<int> RTLIL::IdString::global_free_idx_list_;
+int RTLIL::IdString::last_created_idx_[8];
+int RTLIL::IdString::last_created_idx_ptr_;
 
 RTLIL::Const::Const()
 {
@@ -639,6 +641,30 @@ RTLIL::Module::~Module()
 		delete it->second;
 }
 
+void RTLIL::Module::makeblackbox()
+{
+	pool<RTLIL::Wire*> delwires;
+
+	for (auto it = wires_.begin(); it != wires_.end(); ++it)
+		if (!it->second->port_input && !it->second->port_output)
+			delwires.insert(it->second);
+
+	for (auto it = memories.begin(); it != memories.end(); ++it)
+		delete it->second;
+	memories.clear();
+
+	for (auto it = cells_.begin(); it != cells_.end(); ++it)
+		delete it->second;
+	cells_.clear();
+
+	for (auto it = processes.begin(); it != processes.end(); ++it)
+		delete it->second;
+	processes.clear();
+
+	remove(delwires);
+	set_bool_attribute("\\blackbox");
+}
+
 void RTLIL::Module::reprocess_module(RTLIL::Design *, dict<RTLIL::IdString, RTLIL::Module *>)
 {
 	log_error("Cannot reprocess_module module `%s' !\n", id2cstr(name));
@@ -758,7 +784,7 @@ namespace {
 
 		void check()
 		{
-			if (cell->type.substr(0, 1) != "$" || cell->type.substr(0, 3) == "$__" || cell->type.substr(0, 8) == "$paramod" ||
+			if (cell->type.substr(0, 1) != "$" || cell->type.substr(0, 3) == "$__" || cell->type.substr(0, 8) == "$paramod" || cell->type.substr(0,10) == "$fmcombine" ||
 					cell->type.substr(0, 9) == "$verific$" || cell->type.substr(0, 7) == "$array:" || cell->type.substr(0, 8) == "$extern:")
 				return;
 
@@ -2358,7 +2384,7 @@ void RTLIL::Cell::check()
 
 void RTLIL::Cell::fixup_parameters(bool set_a_signed, bool set_b_signed)
 {
-	if (type.substr(0, 1) != "$" || type.substr(0, 2) == "$_" || type.substr(0, 8) == "$paramod" ||
+	if (type.substr(0, 1) != "$" || type.substr(0, 2) == "$_" || type.substr(0, 8) == "$paramod" || type.substr(0,10) == "$fmcombine" ||
 			type.substr(0, 9) == "$verific$" || type.substr(0, 7) == "$array:" || type.substr(0, 8) == "$extern:")
 		return;
 
@@ -3235,7 +3261,7 @@ void RTLIL::SigSpec::extend_u0(int width, bool is_signed)
 		remove(width, width_ - width);
 
 	if (width_ < width) {
-		RTLIL::SigBit padding = width_ > 0 ? (*this)[width_ - 1] : RTLIL::State::S0;
+		RTLIL::SigBit padding = width_ > 0 ? (*this)[width_ - 1] : RTLIL::State::Sx;
 		if (!is_signed)
 			padding = RTLIL::State::S0;
 		while (width_ < width)
diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index eb71fec7b..ef6eb9f83 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -76,6 +76,9 @@ namespace RTLIL
 
 	struct IdString
 	{
+		#undef YOSYS_XTRACE_GET_PUT
+		#undef YOSYS_SORT_ID_FREE_LIST
+
 		// the global id string cache
 
 		static struct destruct_guard_t {
@@ -89,9 +92,43 @@ namespace RTLIL
 		static dict<char*, int, hash_cstr_ops> global_id_index_;
 		static std::vector<int> global_free_idx_list_;
 
+		static int last_created_idx_ptr_;
+		static int last_created_idx_[8];
+
+		static inline void xtrace_db_dump()
+		{
+		#ifdef YOSYS_XTRACE_GET_PUT
+			for (int idx = 0; idx < GetSize(global_id_storage_); idx++)
+			{
+				if (global_id_storage_.at(idx) == nullptr)
+					log("#X# DB-DUMP index %d: FREE\n", idx);
+				else
+					log("#X# DB-DUMP index %d: '%s' (ref %d)\n", idx, global_id_storage_.at(idx), global_refcount_storage_.at(idx));
+			}
+		#endif
+		}
+
+		static inline void checkpoint()
+		{
+			last_created_idx_ptr_ = 0;
+			for (int i = 0; i < 8; i++) {
+				if (last_created_idx_[i])
+					put_reference(last_created_idx_[i]);
+				last_created_idx_[i] = 0;
+			}
+		#ifdef YOSYS_SORT_ID_FREE_LIST
+			std::sort(global_free_idx_list_.begin(), global_free_idx_list_.end(), std::greater<int>());
+		#endif
+		}
+
 		static inline int get_reference(int idx)
 		{
 			global_refcount_storage_.at(idx)++;
+		#ifdef YOSYS_XTRACE_GET_PUT
+			if (yosys_xtrace) {
+				log("#X# GET-BY-INDEX '%s' (index %d, refcount %d)\n", global_id_storage_.at(idx), idx, global_refcount_storage_.at(idx));
+			}
+		#endif
 			return idx;
 		}
 
@@ -107,6 +144,11 @@ namespace RTLIL
 			auto it = global_id_index_.find((char*)p);
 			if (it != global_id_index_.end()) {
 				global_refcount_storage_.at(it->second)++;
+		#ifdef YOSYS_XTRACE_GET_PUT
+				if (yosys_xtrace) {
+					log("#X# GET-BY-NAME '%s' (index %d, refcount %d)\n", global_id_storage_.at(it->second), it->second, global_refcount_storage_.at(it->second));
+				}
+		#endif
 				return it->second;
 			}
 
@@ -124,16 +166,22 @@ namespace RTLIL
 			global_refcount_storage_.at(idx)++;
 
 			// Avoid Create->Delete->Create pattern
-			static IdString last_created_id;
-			put_reference(last_created_id.index_);
-			last_created_id.index_ = idx;
-			get_reference(last_created_id.index_);
+			if (last_created_idx_[last_created_idx_ptr_])
+				put_reference(last_created_idx_[last_created_idx_ptr_]);
+			last_created_idx_[last_created_idx_ptr_] = idx;
+			get_reference(last_created_idx_[last_created_idx_ptr_]);
+			last_created_idx_ptr_ = (last_created_idx_ptr_ + 1) & 7;
 
 			if (yosys_xtrace) {
 				log("#X# New IdString '%s' with index %d.\n", p, idx);
 				log_backtrace("-X- ", yosys_xtrace-1);
 			}
 
+		#ifdef YOSYS_XTRACE_GET_PUT
+			if (yosys_xtrace) {
+				log("#X# GET-BY-NAME '%s' (index %d, refcount %d)\n", global_id_storage_.at(idx), idx, global_refcount_storage_.at(idx));
+			}
+		#endif
 			return idx;
 		}
 
@@ -144,6 +192,12 @@ namespace RTLIL
 			if (!destruct_guard.ok)
 				return;
 
+		#ifdef YOSYS_XTRACE_GET_PUT
+			if (yosys_xtrace) {
+				log("#X# PUT '%s' (index %d, refcount %d)\n", global_id_storage_.at(idx), idx, global_refcount_storage_.at(idx));
+			}
+		#endif
+
 			log_assert(global_refcount_storage_.at(idx) > 0);
 
 			if (--global_refcount_storage_.at(idx) != 0)
@@ -498,6 +552,14 @@ struct RTLIL::Const
 		return ret;
 	}
 
+	void extu(int width) {
+		bits.resize(width, RTLIL::State::S0);
+	}
+
+	void exts(int width) {
+		bits.resize(width, bits.empty() ? RTLIL::State::Sx : bits.back());
+	}
+
 	inline unsigned int hash() const {
 		unsigned int h = mkhash_init;
 		for (auto b : bits)
@@ -920,6 +982,7 @@ public:
 	virtual void sort();
 	virtual void check();
 	virtual void optimize();
+	virtual void makeblackbox();
 
 	void connect(const RTLIL::SigSig &conn);
 	void connect(const RTLIL::SigSpec &lhs, const RTLIL::SigSpec &rhs);
@@ -1288,7 +1351,7 @@ inline bool RTLIL::SigBit::operator<(const RTLIL::SigBit &other) const {
 		return wire ? (offset < other.offset) : (data < other.data);
 	if (wire != nullptr && other.wire != nullptr)
 		return wire->name < other.wire->name;
-	return wire < other.wire;
+	return (wire != nullptr) < (other.wire != nullptr);
 }
 
 inline bool RTLIL::SigBit::operator==(const RTLIL::SigBit &other) const {
diff --git a/kernel/yosys.cc b/kernel/yosys.cc
index 2ed0f4db4..450e4e4cf 100644
--- a/kernel/yosys.cc
+++ b/kernel/yosys.cc
@@ -33,7 +33,7 @@
 #  include <dlfcn.h>
 #endif
 
-#ifdef _WIN32
+#if defined(_WIN32)
 #  include <windows.h>
 #  include <io.h>
 #elif defined(__APPLE__)
@@ -41,13 +41,15 @@
 #  include <unistd.h>
 #  include <dirent.h>
 #  include <sys/stat.h>
-#  include <glob.h>
 #else
 #  include <unistd.h>
 #  include <dirent.h>
 #  include <sys/types.h>
 #  include <sys/wait.h>
 #  include <sys/stat.h>
+#endif
+
+#if !defined(_WIN32) && defined(YOSYS_ENABLE_GLOB)
 #  include <glob.h>
 #endif
 
@@ -216,12 +218,18 @@ std::string next_token(std::string &text, const char *sep, bool long_strings)
 
 	if (long_strings && pos_begin != text.size() && text[pos_begin] == '"') {
 		string sep_string = sep;
-		for (size_t i = pos_begin+1; i < text.size(); i++)
+		for (size_t i = pos_begin+1; i < text.size(); i++) {
 			if (text[i] == '"' && (i+1 == text.size() || sep_string.find(text[i+1]) != std::string::npos)) {
 				std::string token = text.substr(pos_begin, i-pos_begin+1);
 				text = text.substr(i+1);
 				return token;
 			}
+			if (i+1 < text.size() && text[i] == '"' && text[i+1] == ';' && (i+2 == text.size() || sep_string.find(text[i+2]) != std::string::npos)) {
+				std::string token = text.substr(pos_begin, i-pos_begin+1);
+				text = text.substr(i+2);
+				return token + ";";
+			}
+		}
 	}
 
 	size_t pos_end = text.find_first_of(sep, pos_begin);
@@ -564,7 +572,7 @@ std::vector<std::string> glob_filename(const std::string &filename_pattern)
 {
 	std::vector<std::string> results;
 
-#ifdef _WIN32
+#if defined(_WIN32) || !defined(YOSYS_ENABLE_GLOB)
 	results.push_back(filename_pattern);
 #else
 	glob_t globbuf;
diff --git a/misc/launcher.c b/misc/launcher.c
new file mode 100644
index 000000000..157d68cf3
--- /dev/null
+++ b/misc/launcher.c
@@ -0,0 +1,358 @@
+/* This file comes from the PyPA Setuptools repository, commit 16e452a:
+https://github.com/pypa/setuptools
+Modifications include this comment and inline inclusion of the LICENSE text. */
+
+/* Copyright (C) 2016 Jason R Coombs <jaraco@jaraco.com>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE. */
+
+/*  Setuptools Script Launcher for Windows
+
+    This is a stub executable for Windows that functions somewhat like
+    Effbot's "exemaker", in that it runs a script with the same name but
+    a .py extension, using information from a #! line.  It differs in that
+    it spawns the actual Python executable, rather than attempting to
+    hook into the Python DLL.  This means that the script will run with
+    sys.executable set to the Python executable, where exemaker ends up with
+    sys.executable pointing to itself.  (Which means it won't work if you try
+    to run another Python process using sys.executable.)
+
+    To build/rebuild with mingw32, do this in the setuptools project directory:
+
+       gcc -DGUI=0           -mno-cygwin -O -s -o setuptools/cli.exe launcher.c
+       gcc -DGUI=1 -mwindows -mno-cygwin -O -s -o setuptools/gui.exe launcher.c
+
+    To build for Windows RT, install both Visual Studio Express for Windows 8
+    and for Windows Desktop (both freeware), create "win32" application using
+    "Windows Desktop" version, create new "ARM" target via
+    "Configuration Manager" menu and modify ".vcxproj" file by adding
+    "<WindowsSDKDesktopARMSupport>true</WindowsSDKDesktopARMSupport>" tag
+    as child of "PropertyGroup" tags that has "Debug|ARM" and "Release|ARM"
+    properties.
+
+    It links to msvcrt.dll, but this shouldn't be a problem since it doesn't
+    actually run Python in the same process.  Note that using 'exec' instead
+    of 'spawn' doesn't work, because on Windows this leads to the Python
+    executable running in the *background*, attached to the same console
+    window, meaning you get a command prompt back *before* Python even finishes
+    starting.  So, we have to use spawnv() and wait for Python to exit before
+    continuing.  :(
+*/
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <windows.h>
+#include <tchar.h>
+#include <fcntl.h>
+
+int child_pid=0;
+
+int fail(char *format, char *data) {
+    /* Print error message to stderr and return 2 */
+    fprintf(stderr, format, data);
+    return 2;
+}
+
+char *quoted(char *data) {
+    int i, ln = strlen(data), nb;
+
+    /* We allocate twice as much space as needed to deal with worse-case
+       of having to escape everything. */
+    char *result = calloc(ln*2+3, sizeof(char));
+    char *presult = result;
+
+    *presult++ = '"';
+    for (nb=0, i=0; i < ln; i++)
+      {
+        if (data[i] == '\\')
+          nb += 1;
+        else if (data[i] == '"')
+          {
+            for (; nb > 0; nb--)
+              *presult++ = '\\';
+            *presult++ = '\\';
+          }
+        else
+          nb = 0;
+        *presult++ = data[i];
+      }
+
+    for (; nb > 0; nb--)        /* Deal w trailing slashes */
+      *presult++ = '\\';
+
+    *presult++ = '"';
+    *presult++ = 0;
+    return result;
+}
+
+
+
+
+
+
+
+
+
+
+char *loadable_exe(char *exename) {
+    /* HINSTANCE hPython;  DLL handle for python executable */
+    char *result;
+
+    /* hPython = LoadLibraryEx(exename, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
+    if (!hPython) return NULL; */
+
+    /* Return the absolute filename for spawnv */
+    result = calloc(MAX_PATH, sizeof(char));
+    strncpy(result, exename, MAX_PATH);
+    /*if (result) GetModuleFileNameA(hPython, result, MAX_PATH);
+
+    FreeLibrary(hPython); */
+    return result;
+}
+
+
+char *find_exe(char *exename, char *script) {
+    char drive[_MAX_DRIVE], dir[_MAX_DIR], fname[_MAX_FNAME], ext[_MAX_EXT];
+    char path[_MAX_PATH], c, *result;
+
+    /* convert slashes to backslashes for uniform search below */
+    result = exename;
+    while (c = *result++) if (c=='/') result[-1] = '\\';
+
+    _splitpath(exename, drive, dir, fname, ext);
+    if (drive[0] || dir[0]=='\\') {
+        return loadable_exe(exename);   /* absolute path, use directly */
+    }
+    /* Use the script's parent directory, which should be the Python home
+       (This should only be used for bdist_wininst-installed scripts, because
+        easy_install-ed scripts use the absolute path to python[w].exe
+    */
+    _splitpath(script, drive, dir, fname, ext);
+    result = dir + strlen(dir) -1;
+    if (*result == '\\') result--;
+    while (*result != '\\' && result>=dir) *result-- = 0;
+    _makepath(path, drive, dir, exename, NULL);
+    return loadable_exe(path);
+}
+
+
+char **parse_argv(char *cmdline, int *argc)
+{
+    /* Parse a command line in-place using MS C rules */
+
+    char **result = calloc(strlen(cmdline), sizeof(char *));
+    char *output = cmdline;
+    char c;
+    int nb = 0;
+    int iq = 0;
+    *argc = 0;
+
+    result[0] = output;
+    while (isspace(*cmdline)) cmdline++;   /* skip leading spaces */
+
+    do {
+        c = *cmdline++;
+        if (!c || (isspace(c) && !iq)) {
+            while (nb) {*output++ = '\\'; nb--; }
+            *output++ = 0;
+            result[++*argc] = output;
+            if (!c) return result;
+            while (isspace(*cmdline)) cmdline++;  /* skip leading spaces */
+            if (!*cmdline) return result;  /* avoid empty arg if trailing ws */
+            continue;
+        }
+        if (c == '\\')
+            ++nb;   /* count \'s */
+        else {
+            if (c == '"') {
+                if (!(nb & 1)) { iq = !iq; c = 0; }  /* skip " unless odd # of \ */
+                nb = nb >> 1;   /* cut \'s in half */
+            }
+            while (nb) {*output++ = '\\'; nb--; }
+            if (c) *output++ = c;
+        }
+    } while (1);
+}
+
+void pass_control_to_child(DWORD control_type) {
+    /*
+     * distribute-issue207
+     * passes the control event to child process (Python)
+     */
+    if (!child_pid) {
+        return;
+    }
+    GenerateConsoleCtrlEvent(child_pid,0);
+}
+
+BOOL control_handler(DWORD control_type) {
+    /*
+     * distribute-issue207
+     * control event handler callback function
+     */
+    switch (control_type) {
+        case CTRL_C_EVENT:
+            pass_control_to_child(0);
+            break;
+    }
+    return TRUE;
+}
+
+int create_and_wait_for_subprocess(char* command) {
+    /*
+     * distribute-issue207
+     * launches child process (Python)
+     */
+    DWORD return_value = 0;
+    LPSTR commandline = command;
+    STARTUPINFOA s_info;
+    PROCESS_INFORMATION p_info;
+    ZeroMemory(&p_info, sizeof(p_info));
+    ZeroMemory(&s_info, sizeof(s_info));
+    s_info.cb = sizeof(STARTUPINFO);
+    // set-up control handler callback funciotn
+    SetConsoleCtrlHandler((PHANDLER_ROUTINE) control_handler, TRUE);
+    if (!CreateProcessA(NULL, commandline, NULL, NULL, TRUE, 0, NULL, NULL, &s_info, &p_info)) {
+        fprintf(stderr, "failed to create process.\n");
+        return 0;
+    }
+    child_pid = p_info.dwProcessId;
+    // wait for Python to exit
+    WaitForSingleObject(p_info.hProcess, INFINITE);
+    if (!GetExitCodeProcess(p_info.hProcess, &return_value)) {
+        fprintf(stderr, "failed to get exit code from process.\n");
+        return 0;
+    }
+    return return_value;
+}
+
+char* join_executable_and_args(char *executable, char **args, int argc)
+{
+    /*
+     * distribute-issue207
+     * CreateProcess needs a long string of the executable and command-line arguments,
+     * so we need to convert it from the args that was built
+     */
+    int len,counter;
+    char* cmdline;
+
+    len=strlen(executable)+2;
+    for (counter=1; counter<argc; counter++) {
+        len+=strlen(args[counter])+1;
+    }
+
+    cmdline = (char*)calloc(len, sizeof(char));
+    sprintf(cmdline, "%s", executable);
+    len=strlen(executable);
+    for (counter=1; counter<argc; counter++) {
+        sprintf(cmdline+len, " %s", args[counter]);
+        len+=strlen(args[counter])+1;
+    }
+    return cmdline;
+}
+
+int run(int argc, char **argv, int is_gui) {
+
+    char python[256];   /* python executable's filename*/
+    char *pyopt;        /* Python option */
+    char script[256];   /* the script's filename */
+
+    int scriptf;        /* file descriptor for script file */
+
+    char **newargs, **newargsp, **parsedargs; /* argument array for exec */
+    char *ptr, *end;    /* working pointers for string manipulation */
+    char *cmdline;
+    int i, parsedargc;              /* loop counter */
+
+    /* compute script name from our .exe name*/
+    GetModuleFileNameA(NULL, script, sizeof(script));
+    end = script + strlen(script);
+    while( end>script && *end != '.')
+        *end-- = '\0';
+    *end-- = '\0';
+    strcat(script, (GUI ? "-script.pyw" : "-script.py"));
+
+    /* figure out the target python executable */
+
+    scriptf = open(script, O_RDONLY);
+    if (scriptf == -1) {
+        return fail("Cannot open %s\n", script);
+    }
+    end = python + read(scriptf, python, sizeof(python));
+    close(scriptf);
+
+    ptr = python-1;
+    while(++ptr < end && *ptr && *ptr!='\n' && *ptr!='\r') {;}
+
+    *ptr-- = '\0';
+
+    if (strncmp(python, "#!", 2)) {
+        /* default to python.exe if no #! header */
+        strcpy(python, "#!python.exe");
+    }
+
+    parsedargs = parse_argv(python+2, &parsedargc);
+
+    /* Using spawnv() can fail strangely if you e.g. find the Cygwin
+       Python, so we'll make sure Windows can find and load it */
+
+    ptr = find_exe(parsedargs[0], script);
+    if (!ptr) {
+        return fail("Cannot find Python executable %s\n", parsedargs[0]);
+    }
+
+    /* printf("Python executable: %s\n", ptr); */
+
+    /* Argument array needs to be
+       parsedargc + argc, plus 1 for null sentinel */
+
+    newargs = (char **)calloc(parsedargc + argc + 1, sizeof(char *));
+    newargsp = newargs;
+
+    *newargsp++ = quoted(ptr);
+    for (i = 1; i<parsedargc; i++) *newargsp++ = quoted(parsedargs[i]);
+
+    *newargsp++ = quoted(script);
+    for (i = 1; i < argc; i++)     *newargsp++ = quoted(argv[i]);
+
+    *newargsp++ = NULL;
+
+    /* printf("args 0: %s\nargs 1: %s\n", newargs[0], newargs[1]); */
+
+    if (is_gui) {
+        /* Use exec, we don't need to wait for the GUI to finish */
+        execv(ptr, (const char * const *)(newargs));
+        return fail("Could not exec %s", ptr);   /* shouldn't get here! */
+    }
+
+    /*
+     * distribute-issue207: using CreateProcessA instead of spawnv
+     */
+    cmdline = join_executable_and_args(ptr, newargs, parsedargc + argc);
+    return create_and_wait_for_subprocess(cmdline);
+}
+
+int WINAPI WinMain(HINSTANCE hI, HINSTANCE hP, LPSTR lpCmd, int nShow) {
+    return run(__argc, __argv, GUI);
+}
+
+int main(int argc, char** argv) {
+    return run(argc, argv, GUI);
+}
diff --git a/misc/yosys.proto b/misc/yosys.proto
index 2870176cb..a583e6265 100644
--- a/misc/yosys.proto
+++ b/misc/yosys.proto
@@ -1,12 +1,12 @@
 //
 // yosys -- Yosys Open SYnthesis Suite
-// 
+//
 // Copyright (C) 2018  Serge Bazanski <q3k@symbioticeda.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
@@ -73,7 +73,7 @@ message Module {
         BitVector bits = 2;
     }
     map<string, Port> port = 2;
-    
+
     // Named cells in this module.
     message Cell {
         // Set to true when the name of this cell is automatically created and
@@ -129,7 +129,7 @@ message Model {
             TYPE_FALSE = 6;
         };
         Type type = 1;
-    
+
         message Port {
             // Name of port.
             string portname = 1;
@@ -148,7 +148,7 @@ message Model {
             // Set for AND, NAND.
             Gate gate = 3;
         }
-    
+
         // Set when the node drives given output port(s).
         message OutPort {
             // Name of port.
diff --git a/passes/cmds/rename.cc b/passes/cmds/rename.cc
index 698ce7235..9b1830b7b 100644
--- a/passes/cmds/rename.cc
+++ b/passes/cmds/rename.cc
@@ -24,7 +24,7 @@
 USING_YOSYS_NAMESPACE
 PRIVATE_NAMESPACE_BEGIN
 
-static void rename_in_module(RTLIL::Module *module, std::string from_name, std::string to_name)
+static void rename_in_module(RTLIL::Module *module, std::string from_name, std::string to_name, bool flag_output)
 {
 	from_name = RTLIL::escape_id(from_name);
 	to_name = RTLIL::escape_id(to_name);
@@ -37,13 +37,18 @@ static void rename_in_module(RTLIL::Module *module, std::string from_name, std::
 			Wire *w = it.second;
 			log("Renaming wire %s to %s in module %s.\n", log_id(w), log_id(to_name), log_id(module));
 			module->rename(w, to_name);
-			if (w->port_id)
+			if (w->port_id || flag_output) {
+				if (flag_output)
+					w->port_output = true;
 				module->fixup_ports();
+			}
 			return;
 		}
 
 	for (auto &it : module->cells_)
 		if (it.first == from_name) {
+			if (flag_output)
+				log_cmd_error("Called with -output but the specified object is a cell.\n");
 			log("Renaming cell %s to %s in module %s.\n", log_id(it.second), log_id(to_name), log_id(module));
 			module->rename(it.second, to_name);
 			return;
@@ -108,15 +113,26 @@ struct RenamePass : public Pass {
 		log("Rename the specified object. Note that selection patterns are not supported\n");
 		log("by this command.\n");
 		log("\n");
+		log("\n");
+		log("\n");
+		log("    rename -output old_name new_name\n");
+		log("\n");
+		log("Like above, but also make the wire an output. This will fail if the object is\n");
+		log("not a wire.\n");
+		log("\n");
+		log("\n");
 		log("    rename -src [selection]\n");
 		log("\n");
 		log("Assign names auto-generated from the src attribute to all selected wires and\n");
 		log("cells with private names.\n");
 		log("\n");
+		log("\n");
 		log("    rename -wire [selection]\n");
+		log("\n");
 		log("Assign auto-generated names based on the wires they drive to all selected\n");
 		log("cells with private names. Ignores cells driving privatly named wires.\n");
 		log("\n");
+		log("\n");
 		log("    rename -enumerate [-pattern <pattern>] [selection]\n");
 		log("\n");
 		log("Assign short auto-generated names to all selected wires and cells with private\n");
@@ -124,11 +140,13 @@ struct RenamePass : public Pass {
 		log("The character %% in the pattern is replaced with a integer number. The default\n");
 		log("pattern is '_%%_'.\n");
 		log("\n");
+		log("\n");
 		log("    rename -hide [selection]\n");
 		log("\n");
 		log("Assign private names (the ones with $-prefix) to all selected wires and cells\n");
 		log("with public names. This ignores all selected ports.\n");
 		log("\n");
+		log("\n");
 		log("    rename -top new_name\n");
 		log("\n");
 		log("Rename top module.\n");
@@ -142,6 +160,7 @@ struct RenamePass : public Pass {
 		bool flag_enumerate = false;
 		bool flag_hide = false;
 		bool flag_top = false;
+		bool flag_output = false;
 		bool got_mode = false;
 
 		size_t argidx;
@@ -153,6 +172,11 @@ struct RenamePass : public Pass {
 				got_mode = true;
 				continue;
 			}
+			if (arg == "-output" && !got_mode) {
+				flag_output = true;
+				got_mode = true;
+				continue;
+			}
 			if (arg == "-wire" && !got_mode) {
 				flag_wire = true;
 				got_mode = true;
@@ -322,10 +346,12 @@ struct RenamePass : public Pass {
 			if (!design->selected_active_module.empty())
 			{
 				if (design->modules_.count(design->selected_active_module) > 0)
-					rename_in_module(design->modules_.at(design->selected_active_module), from_name, to_name);
+					rename_in_module(design->modules_.at(design->selected_active_module), from_name, to_name, flag_output);
 			}
 			else
 			{
+				if (flag_output)
+					log_cmd_error("Mode -output requires that there is an active module selected.\n");
 				for (auto &mod : design->modules_) {
 					if (mod.first == from_name || RTLIL::unescape_id(mod.first) == from_name) {
 						to_name = RTLIL::escape_id(to_name);
diff --git a/passes/hierarchy/hierarchy.cc b/passes/hierarchy/hierarchy.cc
index 2d8edebb5..88c339e8c 100644
--- a/passes/hierarchy/hierarchy.cc
+++ b/passes/hierarchy/hierarchy.cc
@@ -910,7 +910,7 @@ struct HierarchyPass : public Pass {
 			if (m == nullptr)
 				continue;
 
-			if (m->get_bool_attribute("\\blackbox") && !cell->parameters.empty()) {
+			if (m->get_bool_attribute("\\blackbox") && !cell->parameters.empty() && m->get_bool_attribute("\\dynports")) {
 				IdString new_m_name = m->derive(design, cell->parameters, true);
 				if (new_m_name.empty())
 					continue;
diff --git a/passes/hierarchy/uniquify.cc b/passes/hierarchy/uniquify.cc
index c88ecd82e..e6154e94f 100644
--- a/passes/hierarchy/uniquify.cc
+++ b/passes/hierarchy/uniquify.cc
@@ -87,6 +87,8 @@ struct UniquifyPass : public Pass {
 					smod->name = newname;
 					cell->type = newname;
 					smod->set_bool_attribute("\\unique");
+					if (smod->attributes.count("\\hdlname") == 0)
+						smod->attributes["\\hdlname"] = string(log_id(tmod->name));
 					design->add(smod);
 
 					did_something = true;
diff --git a/passes/memory/memory_bram.cc b/passes/memory/memory_bram.cc
index cf4095d06..ddc56d9b5 100644
--- a/passes/memory/memory_bram.cc
+++ b/passes/memory/memory_bram.cc
@@ -542,7 +542,7 @@ bool replace_cell(Cell *cell, const rules_t &rules, const rules_t::bram_t &bram,
 	}
 
 	// assign write ports
-
+	pair<SigBit, bool> wr_clkdom;
 	for (int cell_port_i = 0, bram_port_i = 0; cell_port_i < wr_ports; cell_port_i++)
 	{
 		bool clken = wr_clken[cell_port_i] == State::S1;
@@ -552,7 +552,7 @@ bool replace_cell(Cell *cell, const rules_t &rules, const rules_t::bram_t &bram,
 		pair<SigBit, bool> clkdom(clksig, clkpol);
 		if (!clken)
 			clkdom = pair<SigBit, bool>(State::S1, false);
-
+		wr_clkdom = clkdom;
 		log("      Write port #%d is in clock domain %s%s.\n",
 				cell_port_i, clkdom.second ? "" : "!",
 				clken ? log_signal(clkdom.first) : "~async~");
@@ -641,6 +641,7 @@ grow_read_ports:;
 				pi.sig_data = SigSpec();
 				pi.sig_en = SigSpec();
 				pi.make_outreg = false;
+				pi.make_transp = false;
 			}
 			new_portinfos.push_back(pi);
 			if (pi.dupidx == dup_count-1) {
@@ -718,7 +719,13 @@ grow_read_ports:;
 				if (read_transp.count(pi.transp) && read_transp.at(pi.transp) != transp) {
 					if (match.make_transp && wr_ports <= 1) {
 						pi.make_transp = true;
-						enable_make_transp = true;
+						if (pi.clocks != 0) {
+							if (wr_ports == 1 && wr_clkdom != clkdom) {								
+								log("        Bram port %c%d.%d cannot have soft transparency logic added as read and write clock domains differ.\n", pi.group + 'A', pi.index + 1, pi.dupidx + 1);
+								goto skip_bram_rport;
+							}
+							enable_make_transp = true;
+						}
 					} else {
 						log("        Bram port %c%d.%d has incompatible read transparency.\n", pi.group + 'A', pi.index + 1, pi.dupidx + 1);
 						goto skip_bram_rport;
@@ -737,7 +744,8 @@ grow_read_ports:;
 			if (clken) {
 				clock_domains[pi.clocks] = clkdom;
 				clock_polarities[pi.clkpol] = clkdom.second;
-				read_transp[pi.transp] = transp;
+				if (!pi.make_transp)
+					read_transp[pi.transp] = transp;
 				pi.sig_clock = clkdom.first;
 				pi.sig_en = rd_en[cell_port_i];
 				pi.effective_clkpol = clkdom.second;
@@ -913,17 +921,18 @@ grow_read_ports:;
 				} else {
 					SigSpec bram_dout = module->addWire(NEW_ID, bram.dbits);
 					c->setPort(stringf("\\%sDATA", pf), bram_dout);
-
-					if (pi.make_outreg) {
+					if (pi.make_outreg && pi.make_transp) {
+						log("        Moving output register to address for transparent port %c%d.%d.\n", pi.group + 'A', pi.index + 1, pi.dupidx + 1);
+						SigSpec sig_addr_q = module->addWire(NEW_ID, bram.abits);
+						module->addDff(NEW_ID, pi.sig_clock, sig_addr, sig_addr_q, pi.effective_clkpol);
+						c->setPort(stringf("\\%sADDR", pf), sig_addr_q);
+					} else if (pi.make_outreg) {
 						SigSpec bram_dout_q = module->addWire(NEW_ID, bram.dbits);
 						if (!pi.sig_en.empty())
 							bram_dout = module->Mux(NEW_ID, bram_dout_q, bram_dout, pi.sig_en);
 						module->addDff(NEW_ID, pi.sig_clock, bram_dout, bram_dout_q, pi.effective_clkpol);
 						bram_dout = bram_dout_q;
-					}
-
-					if (pi.make_transp)
-					{
+					} else if (pi.make_transp) {
 						log("        Adding extra logic for transparent port %c%d.%d.\n", pi.group + 'A', pi.index + 1, pi.dupidx + 1);
 
 						SigSpec transp_en_d = module->Mux(NEW_ID, SigSpec(0, make_transp_enbits),
@@ -949,6 +958,8 @@ grow_read_ports:;
 					SigSpec addr_ok_q = addr_ok;
 					if ((pi.clocks || pi.make_outreg) && !addr_ok.empty()) {
 						addr_ok_q = module->addWire(NEW_ID);
+						if (!pi.sig_en.empty())
+							addr_ok = module->Mux(NEW_ID, addr_ok_q, addr_ok, pi.sig_en);
 						module->addDff(NEW_ID, pi.sig_clock, addr_ok, addr_ok_q, pi.effective_clkpol);
 					}
 
diff --git a/passes/opt/opt_expr.cc b/passes/opt/opt_expr.cc
index 26a3ca7bc..a05db2a4f 100644
--- a/passes/opt/opt_expr.cc
+++ b/passes/opt/opt_expr.cc
@@ -155,6 +155,13 @@ bool group_cell_inputs(RTLIL::Module *module, RTLIL::Cell *cell, bool commutativ
 			new_b.append_bit(it.first.second);
 		}
 
+		if (cell->type.in("$and", "$or") && i == GRP_CONST_A) {
+			log("  Direct Connection: %s (%s with %s)\n", log_signal(new_b), log_id(cell->type), log_signal(new_a));
+			module->connect(new_y, new_b);
+			module->connect(new_conn);
+			continue;
+		}
+
 		RTLIL::Cell *c = module->addCell(NEW_ID, cell->type);
 
 		c->setPort("\\A", new_a);
diff --git a/passes/opt/wreduce.cc b/passes/opt/wreduce.cc
index 09983bc67..52245ce3e 100644
--- a/passes/opt/wreduce.cc
+++ b/passes/opt/wreduce.cc
@@ -53,6 +53,8 @@ struct WreduceWorker
 	std::set<Cell*, IdString::compare_ptr_by_name<Cell>> work_queue_cells;
 	std::set<SigBit> work_queue_bits;
 	pool<SigBit> keep_bits;
+	dict<SigBit, State> init_bits;
+	pool<SigBit> remove_init_bits;
 
 	WreduceWorker(WreduceConfig *config, Module *module) :
 			config(config), module(module), mi(module) { }
@@ -141,6 +143,7 @@ struct WreduceWorker
 
 		SigSpec sig_d = mi.sigmap(cell->getPort("\\D"));
 		SigSpec sig_q = mi.sigmap(cell->getPort("\\Q"));
+		Const initval;
 
 		int width_before = GetSize(sig_q);
 
@@ -150,24 +153,35 @@ struct WreduceWorker
 		bool zero_ext = sig_d[GetSize(sig_d)-1] == State::S0;
 		bool sign_ext = !zero_ext;
 
+		for (int i = 0; i < GetSize(sig_q); i++) {
+			SigBit bit = sig_q[i];
+			if (init_bits.count(bit))
+				initval.bits.push_back(init_bits.at(bit));
+			else
+				initval.bits.push_back(State::Sx);
+		}
+
 		for (int i = GetSize(sig_q)-1; i >= 0; i--)
 		{
-			if (zero_ext && sig_d[i] == State::S0) {
+			if (zero_ext && sig_d[i] == State::S0 && (initval[i] == State::S0 || initval[i] == State::Sx)) {
 				module->connect(sig_q[i], State::S0);
+				remove_init_bits.insert(sig_q[i]);
 				sig_d.remove(i);
 				sig_q.remove(i);
 				continue;
 			}
 
-			if (sign_ext && i > 0 && sig_d[i] == sig_d[i-1]) {
+			if (sign_ext && i > 0 && sig_d[i] == sig_d[i-1] && initval[i] == initval[i-1]) {
 				module->connect(sig_q[i], sig_q[i-1]);
+				remove_init_bits.insert(sig_q[i]);
 				sig_d.remove(i);
 				sig_q.remove(i);
 				continue;
 			}
 
 			auto info = mi.query(sig_q[i]);
-			if (!info->is_output && GetSize(info->ports) <= 1 && !keep_bits.count(mi.sigmap(sig_q[i]))) {
+			if (!info->is_output && GetSize(info->ports) == 1 && !keep_bits.count(mi.sigmap(sig_q[i]))) {
+				remove_init_bits.insert(sig_q[i]);
 				sig_d.remove(i);
 				sig_q.remove(i);
 				zero_ext = false;
@@ -183,10 +197,11 @@ struct WreduceWorker
 
 		if (GetSize(sig_q) == 0) {
 			log("Removed cell %s.%s (%s).\n", log_id(module), log_id(cell), log_id(cell->type));
+			module->remove(cell);
 			return;
 		}
 
-		log("Removed top %d bits (of %d) from mux cell %s.%s (%s).\n", width_before - GetSize(sig_q), width_before,
+		log("Removed top %d bits (of %d) from FF cell %s.%s (%s).\n", width_before - GetSize(sig_q), width_before,
 				log_id(module), log_id(cell), log_id(cell->type));
 
 		for (auto bit : sig_d)
@@ -376,10 +391,21 @@ struct WreduceWorker
 
 	void run()
 	{
-		for (auto w : module->wires())
+		// create a copy as mi.sigmap will be updated as we process the module
+		SigMap init_attr_sigmap = mi.sigmap;
+
+		for (auto w : module->wires()) {
 			if (w->get_bool_attribute("\\keep"))
 				for (auto bit : mi.sigmap(w))
 					keep_bits.insert(bit);
+			if (w->attributes.count("\\init")) {
+				Const initval = w->attributes.at("\\init");
+				SigSpec initsig = init_attr_sigmap(w);
+				int width = std::min(GetSize(initval), GetSize(initsig));
+				for (int i = 0; i < width; i++)
+					init_bits[initsig[i]] = initval[i];
+			}
+		}
 
 		for (auto c : module->selected_cells())
 			work_queue_cells.insert(c);
@@ -427,6 +453,24 @@ struct WreduceWorker
 			module->connect(nw, SigSpec(w).extract(0, GetSize(nw)));
 			module->swap_names(w, nw);
 		}
+
+		if (!remove_init_bits.empty()) {
+			for (auto w : module->wires()) {
+				if (w->attributes.count("\\init")) {
+					Const initval = w->attributes.at("\\init");
+					Const new_initval(State::Sx, GetSize(w));
+					SigSpec initsig = init_attr_sigmap(w);
+					int width = std::min(GetSize(initval), GetSize(initsig));
+					for (int i = 0; i < width; i++) {
+						log_dump(initsig[i], remove_init_bits.count(initsig[i]));
+						if (!remove_init_bits.count(initsig[i]))
+							new_initval[i] = initval[i];
+					}
+					w->attributes.at("\\init") = new_initval;
+					log_dump(w->name, initval, new_initval);
+				}
+			}
+		}
 	}
 };
 
diff --git a/passes/pmgen/Makefile.inc b/passes/pmgen/Makefile.inc
index 33baaca30..e0609d9ba 100644
--- a/passes/pmgen/Makefile.inc
+++ b/passes/pmgen/Makefile.inc
@@ -4,5 +4,5 @@ passes/pmgen/ice40_dsp.o: passes/pmgen/ice40_dsp_pm.h
 EXTRA_OBJS += passes/pmgen/ice40_dsp_pm.h
 .SECONDARY: passes/pmgen/ice40_dsp_pm.h
 
-passes/pmgen/ice40_dsp_pm.h: passes/pmgen/ice40_dsp.pmg passes/pmgen/pmgen.py
-	$(P) cd passes/pmgen && python3 pmgen.py ice40_dsp
+passes/pmgen/ice40_dsp_pm.h: passes/pmgen/pmgen.py passes/pmgen/ice40_dsp.pmg
+	$(P) mkdir -p passes/pmgen && python3 $^ $@
diff --git a/passes/pmgen/README.md b/passes/pmgen/README.md
index a1007dc62..223b43059 100644
--- a/passes/pmgen/README.md
+++ b/passes/pmgen/README.md
@@ -16,7 +16,7 @@ API of Generated Matcher
 ========================
 
 When `pmgen.py` reads a `foobar.pmg` file, it writes `foobar_pm.h` containing
-a class `foobar_pm`. That class is instanciated with an RTLIL module and a
+a class `foobar_pm`. That class is instantiated with an RTLIL module and a
 list of cells from that module:
 
     foobar_pm pm(module, module->selected_cells());
@@ -142,7 +142,7 @@ The `select` lines are evaluated once for each cell when the matcher is
 initialized. A `match` block will only consider cells for which all `select`
 expressions evaluated to `true`. Note that the state variable corresponding to
 the match (in the example `mul`) is the only state variable that may be used
-`select` lines.
+in `select` lines.
 
 Index lines are using the `index <type> expr1 === expr2` syntax.  `expr1` is
 evaluated during matcher initialization and the same restrictions apply as for
diff --git a/passes/pmgen/pmgen.py b/passes/pmgen/pmgen.py
index e688a4567..d9747b065 100644
--- a/passes/pmgen/pmgen.py
+++ b/passes/pmgen/pmgen.py
@@ -6,7 +6,11 @@ import pprint
 
 pp = pprint.PrettyPrinter(indent=4)
 
-prefix = sys.argv[1]
+pmgfile = sys.argv[1]
+assert pmgfile.endswith(".pmg")
+prefix = pmgfile[0:-4]
+prefix = prefix.split('/')[-1]
+outfile = sys.argv[2]
 
 state_types = dict()
 udata_types = dict()
@@ -73,7 +77,7 @@ def rewrite_cpp(s):
 
     return "".join(t)
 
-with open("%s.pmg" % prefix, "r") as f:
+with open(pmgfile, "r") as f:
     while True:
         line = f.readline()
         if line == "": break
@@ -82,7 +86,7 @@ with open("%s.pmg" % prefix, "r") as f:
         cmd = line.split()
         if len(cmd) == 0 or cmd[0].startswith("//"): continue
         cmd = cmd[0]
-        
+
         if cmd == "state":
             m = re.match(r"^state\s+<(.*?)>\s+(([A-Za-z_][A-Za-z_0-9]*\s+)*[A-Za-z_][A-Za-z_0-9]*)\s*$", line)
             assert m
@@ -176,7 +180,7 @@ with open("%s.pmg" % prefix, "r") as f:
 
             blocks.append(block)
 
-with open("%s_pm.h" % prefix, "w") as f:
+with open(outfile, "w") as f:
     print("// Generated by pmgen.py from {}.pgm".format(prefix), file=f)
     print("", file=f)
 
diff --git a/passes/proc/proc_mux.cc b/passes/proc/proc_mux.cc
index 1329c1fef..bac2dc2cd 100644
--- a/passes/proc/proc_mux.cc
+++ b/passes/proc/proc_mux.cc
@@ -340,6 +340,7 @@ RTLIL::SigSpec signal_to_mux_tree(RTLIL::Module *mod, SnippetSwCache &swcache, d
 		// evaluate in reverse order to give the first entry the top priority
 		RTLIL::SigSpec initial_val = result;
 		RTLIL::Cell *last_mux_cell = NULL;
+		bool shiftx = initial_val.is_fully_undef();
 		for (size_t i = 0; i < sw->cases.size(); i++) {
 			int case_idx = sw->cases.size() - i - 1;
 			RTLIL::CaseRule *cs2 = sw->cases[case_idx];
@@ -348,6 +349,33 @@ RTLIL::SigSpec signal_to_mux_tree(RTLIL::Module *mod, SnippetSwCache &swcache, d
 				append_pmux(mod, sw->signal, cs2->compare, value, last_mux_cell, sw, ifxmode);
 			else
 				result = gen_mux(mod, sw->signal, cs2->compare, value, result, last_mux_cell, sw, ifxmode);
+
+			// Ignore output values which are entirely don't care
+			if (shiftx && !value.is_fully_undef()) {
+				// Keep checking if case condition is the same as the current case index
+				if (cs2->compare.size() == 1 && cs2->compare.front().is_fully_const())
+					shiftx = (cs2->compare.front().as_int() == case_idx);
+				else
+					shiftx = false;
+			}
+		}
+
+		// Transform into a $shiftx where possible
+		if (shiftx && last_mux_cell && last_mux_cell->type == "$pmux") {
+			// Create bit-blasted $shiftx-es that shifts by the address line used in the case statement
+			auto pmux_b_port = last_mux_cell->getPort("\\B");
+			auto pmux_y_port = last_mux_cell->getPort("\\Y");
+			int width = last_mux_cell->getParam("\\WIDTH").as_int();
+			for (int i = 0; i < width; ++i) {
+				RTLIL::SigSpec a_port;
+				// Because we went in reverse order above, un-reverse $pmux's B port here
+				for (int j = pmux_b_port.size()/width-1; j >= 0; --j)
+					a_port.append(pmux_b_port.extract(j*width+i, 1));
+				// Create a $shiftx that shifts by the address line used in the case statement
+				mod->addShiftx(NEW_ID, a_port, sw->signal, pmux_y_port.extract(i, 1));
+			}
+			// Disconnect $pmux by replacing its output port with a floating wire
+			last_mux_cell->setPort("\\Y", mod->addWire(NEW_ID, width));
 		}
 	}
 
diff --git a/passes/sat/Makefile.inc b/passes/sat/Makefile.inc
index 8ab0280c0..fc3ac879e 100644
--- a/passes/sat/Makefile.inc
+++ b/passes/sat/Makefile.inc
@@ -8,4 +8,8 @@ OBJS += passes/sat/expose.o
 OBJS += passes/sat/assertpmux.o
 OBJS += passes/sat/clk2fflogic.o
 OBJS += passes/sat/async2sync.o
+OBJS += passes/sat/supercover.o
+OBJS += passes/sat/fmcombine.o
+OBJS += passes/sat/mutate.o
+OBJS += passes/sat/cutpoint.o
 
diff --git a/passes/sat/async2sync.cc b/passes/sat/async2sync.cc
index c92db7118..d045d0dcb 100644
--- a/passes/sat/async2sync.cc
+++ b/passes/sat/async2sync.cc
@@ -39,7 +39,7 @@ struct Async2syncPass : public Pass {
 		log("reset value in the next cycle regardless of the data-in value at the time of\n");
 		log("the clock edge.\n");
 		log("\n");
-		log("Currently only $adff cells are supported by this pass.\n");
+		log("Currently only $adff and $dffsr cells are supported by this pass.\n");
 		log("\n");
 	}
 	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
@@ -84,7 +84,7 @@ struct Async2syncPass : public Pass {
 					bool arst_pol = cell->parameters["\\ARST_POLARITY"].as_bool();
 					Const arst_val = cell->parameters["\\ARST_VALUE"];
 
-					SigSpec sig_clk = cell->getPort("\\CLK");
+					// SigSpec sig_clk = cell->getPort("\\CLK");
 					SigSpec sig_arst = cell->getPort("\\ARST");
 					SigSpec sig_d = cell->getPort("\\D");
 					SigSpec sig_q = cell->getPort("\\Q");
@@ -120,6 +120,55 @@ struct Async2syncPass : public Pass {
 					cell->type = "$dff";
 					continue;
 				}
+
+				if (cell->type.in("$dffsr"))
+				{
+					// bool clk_pol = cell->parameters["\\CLK_POLARITY"].as_bool();
+					bool set_pol = cell->parameters["\\SET_POLARITY"].as_bool();
+					bool clr_pol = cell->parameters["\\CLR_POLARITY"].as_bool();
+
+					// SigSpec sig_clk = cell->getPort("\\CLK");
+					SigSpec sig_set = cell->getPort("\\SET");
+					SigSpec sig_clr = cell->getPort("\\CLR");
+					SigSpec sig_d = cell->getPort("\\D");
+					SigSpec sig_q = cell->getPort("\\Q");
+
+					log("Replacing %s.%s (%s): SET=%s, CLR=%s, D=%s, Q=%s\n",
+							log_id(module), log_id(cell), log_id(cell->type),
+							log_signal(sig_set), log_signal(sig_clr), log_signal(sig_d), log_signal(sig_q));
+
+					Const init_val;
+					for (int i = 0; i < GetSize(sig_q); i++) {
+						SigBit bit = sigmap(sig_q[i]);
+						init_val.bits.push_back(initbits.count(bit) ? initbits.at(bit) : State::Sx);
+						del_initbits.insert(bit);
+					}
+
+					Wire *new_d = module->addWire(NEW_ID, GetSize(sig_d));
+					Wire *new_q = module->addWire(NEW_ID, GetSize(sig_q));
+					new_q->attributes["\\init"] = init_val;
+
+					if (!set_pol)
+						sig_set = module->Not(NEW_ID, sig_set);
+
+					if (clr_pol)
+						sig_clr = module->Not(NEW_ID, sig_clr);
+
+					SigSpec tmp = module->Or(NEW_ID, sig_d, sig_set);
+					module->addAnd(NEW_ID, tmp, sig_clr, new_d);
+
+					tmp = module->Or(NEW_ID, new_q, sig_set);
+					module->addAnd(NEW_ID, tmp, sig_clr, sig_q);
+
+					cell->setPort("\\D", new_d);
+					cell->setPort("\\Q", new_q);
+					cell->unsetPort("\\SET");
+					cell->unsetPort("\\CLR");
+					cell->unsetParam("\\SET_POLARITY");
+					cell->unsetParam("\\CLR_POLARITY");
+					cell->type = "$dff";
+					continue;
+				}
 			}
 
 			for (auto wire : module->wires())
diff --git a/passes/sat/cutpoint.cc b/passes/sat/cutpoint.cc
new file mode 100644
index 000000000..048aec7f3
--- /dev/null
+++ b/passes/sat/cutpoint.cc
@@ -0,0 +1,168 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *
+ *  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 CutpointPass : public Pass {
+	CutpointPass() : Pass("cutpoint", "add hi/lo cover cells for each wire bit") { }
+	void help() YS_OVERRIDE
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    cutpoint [options] [selection]\n");
+		log("\n");
+		log("This command adds formal cut points to the design.\n");
+		log("\n");
+		log("    -undef\n");
+		log("        set cupoint nets to undef (x). the default behavior is to create a\n");
+		log("        $anyseq cell and drive the cutpoint net from that\n");
+		log("\n");
+	}
+	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
+	{
+		 bool flag_undef = false;
+
+		log_header(design, "Executing CUTPOINT pass.\n");
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++)
+		{
+			if (args[argidx] == "-undef") {
+				flag_undef = true;
+				continue;
+			}
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		for (auto module : design->selected_modules())
+		{
+			if (design->selected_whole_module(module->name)) {
+				log("Making all outputs of module %s cut points, removing module contents.\n", log_id(module));
+				module->new_connections(std::vector<RTLIL::SigSig>());
+				for (auto cell : vector<Cell*>(module->cells()))
+					module->remove(cell);
+				vector<Wire*> output_wires;
+				for (auto wire : module->wires())
+					if (wire->port_output)
+						output_wires.push_back(wire);
+				for (auto wire : output_wires)
+					module->connect(wire, flag_undef ? Const(State::Sx, GetSize(wire)) : module->Anyseq(NEW_ID, GetSize(wire)));
+				continue;
+			}
+
+			SigMap sigmap(module);
+			pool<SigBit> cutpoint_bits;
+
+			for (auto cell : module->selected_cells()) {
+				if (cell->type == "$anyseq")
+					continue;
+				log("Removing cell %s.%s, making all cell outputs cutpoints.\n", log_id(module), log_id(cell));
+				for (auto &conn : cell->connections()) {
+					if (cell->output(conn.first))
+						module->connect(conn.second, flag_undef ? Const(State::Sx, GetSize(conn.second)) : module->Anyseq(NEW_ID, GetSize(conn.second)));
+				}
+				module->remove(cell);
+			}
+
+			for (auto wire : module->selected_wires()) {
+				if (wire->port_output) {
+					log("Making output wire %s.%s a cutpoint.\n", log_id(module), log_id(wire));
+					Wire *new_wire = module->addWire(NEW_ID, wire);
+					module->swap_names(wire, new_wire);
+					module->connect(new_wire, flag_undef ? Const(State::Sx, GetSize(new_wire)) : module->Anyseq(NEW_ID, GetSize(new_wire)));
+					wire->port_id = 0;
+					wire->port_input = false;
+					wire->port_output = false;
+					continue;
+				}
+				log("Making wire %s.%s a cutpoint.\n", log_id(module), log_id(wire));
+				for (auto bit : sigmap(wire))
+					cutpoint_bits.insert(bit);
+			}
+
+			if (!cutpoint_bits.empty())
+			{
+				for (auto cell : module->cells()) {
+					for (auto &conn : cell->connections()) {
+						if (!cell->output(conn.first))
+							continue;
+						SigSpec sig = sigmap(conn.second);
+						int bit_count = 0;
+						for (auto &bit : sig) {
+							if (cutpoint_bits.count(bit))
+								bit_count++;
+						}
+						if (bit_count == 0)
+							continue;
+						SigSpec dummy = module->addWire(NEW_ID, bit_count);
+						bit_count = 0;
+						for (auto &bit : sig) {
+							if (cutpoint_bits.count(bit))
+								bit = dummy[bit_count++];
+						}
+						cell->setPort(conn.first, sig);
+					}
+				}
+
+				vector<Wire*> rewrite_wires;
+				for (auto wire : module->wires()) {
+					if (!wire->port_input)
+						continue;
+					int bit_count = 0;
+					for (auto &bit : sigmap(wire))
+						if (cutpoint_bits.count(bit))
+							bit_count++;
+					if (bit_count)
+						rewrite_wires.push_back(wire);
+				}
+
+				for (auto wire : rewrite_wires) {
+					Wire *new_wire = module->addWire(NEW_ID, wire);
+					SigSpec lhs, rhs, sig = sigmap(wire);
+					for (int i = 0; i < GetSize(sig); i++)
+						if (!cutpoint_bits.count(sig[i])) {
+							lhs.append(SigBit(wire, i));
+							rhs.append(SigBit(new_wire, i));
+						}
+					if (GetSize(lhs))
+						module->connect(lhs, rhs);
+					module->swap_names(wire, new_wire);
+					wire->port_id = 0;
+					wire->port_input = false;
+					wire->port_output = false;
+				}
+
+				SigSpec sig(cutpoint_bits);
+				sig.sort_and_unify();
+
+				for (auto chunk : sig.chunks()) {
+					SigSpec s(chunk);
+					module->connect(s, flag_undef ? Const(State::Sx, GetSize(s)) : module->Anyseq(NEW_ID, GetSize(s)));
+				}
+			}
+		}
+	}
+} CutpointPass;
+
+PRIVATE_NAMESPACE_END
diff --git a/passes/sat/fmcombine.cc b/passes/sat/fmcombine.cc
new file mode 100644
index 000000000..cd75ca860
--- /dev/null
+++ b/passes/sat/fmcombine.cc
@@ -0,0 +1,341 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *
+ *  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"
+#include "kernel/celltypes.h"
+
+USING_YOSYS_NAMESPACE
+PRIVATE_NAMESPACE_BEGIN
+
+struct opts_t
+{
+	bool fwd = false;
+	bool bwd = false;
+	bool nop = false;
+};
+
+struct FmcombineWorker
+{
+	const opts_t &opts;
+	Design *design;
+	Module *original = nullptr;
+	Module *module = nullptr;
+	IdString orig_type, combined_type;
+
+	FmcombineWorker(Design *design, IdString orig_type, const opts_t &opts) :
+			opts(opts), design(design), original(design->module(orig_type)),
+			orig_type(orig_type), combined_type("$fmcombine" + orig_type.str())
+	{
+	}
+
+	SigSpec import_sig(SigSpec sig, const string &suffix)
+	{
+		SigSpec newsig;
+		for (auto chunk : sig.chunks()) {
+			if (chunk.wire != nullptr)
+				chunk.wire = module->wire(chunk.wire->name.str() + suffix);
+			newsig.append(chunk);
+		}
+		return newsig;
+	}
+
+	void import_prim_cell(Cell *cell, const string &suffix)
+	{
+		Cell *c = module->addCell(cell->name.str() + suffix, cell->type);
+		c->parameters = cell->parameters;
+		c->attributes = cell->attributes;
+
+		for (auto &conn : cell->connections())
+			c->setPort(conn.first, import_sig(conn.second, suffix));
+	}
+
+	void import_hier_cell(Cell *cell)
+	{
+		if (!cell->parameters.empty())
+			log_cmd_error("Cell %s.%s has unresolved instance parameters.\n", log_id(original), log_id(cell));
+
+		FmcombineWorker sub_worker(design, cell->type, opts);
+		sub_worker.generate();
+
+		Cell *c = module->addCell(cell->name.str() + "_combined", sub_worker.combined_type);
+		// c->parameters = cell->parameters;
+		c->attributes = cell->attributes;
+
+		for (auto &conn : cell->connections()) {
+			c->setPort(conn.first.str() + "_gold", import_sig(conn.second, "_gold"));
+			c->setPort(conn.first.str() + "_gate", import_sig(conn.second, "_gate"));
+		}
+	}
+
+	void generate()
+	{
+		if (design->module(combined_type)) {
+			// log("Combined module %s already exists.\n", log_id(combined_type));
+			return;
+		}
+
+		log("Generating combined module %s from module %s.\n", log_id(combined_type), log_id(orig_type));
+		module = design->addModule(combined_type);
+
+		for (auto wire : original->wires()) {
+			module->addWire(wire->name.str() + "_gold", wire);
+			module->addWire(wire->name.str() + "_gate", wire);
+		}
+		module->fixup_ports();
+
+		for (auto cell : original->cells()) {
+			if (design->module(cell->type) == nullptr) {
+				import_prim_cell(cell, "_gold");
+				import_prim_cell(cell, "_gate");
+			} else {
+				import_hier_cell(cell);
+			}
+		}
+
+		for (auto &conn : original->connections()) {
+			module->connect(import_sig(conn.first, "_gold"), import_sig(conn.second, "_gold"));
+			module->connect(import_sig(conn.first, "_gate"), import_sig(conn.second, "_gate"));
+		}
+
+		if (opts.nop)
+			return;
+
+		CellTypes ct;
+		ct.setup_internals_eval();
+		ct.setup_stdcells_eval();
+
+		SigMap sigmap(module);
+
+		dict<SigBit, SigBit> data_bit_to_eq_net;
+		dict<Cell*, SigSpec> cell_to_eq_nets;
+		dict<SigSpec, SigSpec> reduce_db;
+		dict<SigSpec, SigSpec> invert_db;
+
+		for (auto cell : original->cells())
+		{
+			if (!ct.cell_known(cell->type))
+				continue;
+
+			for (auto &conn : cell->connections())
+			{
+				if (!cell->output(conn.first))
+					continue;
+
+				SigSpec A = import_sig(conn.second, "_gold");
+				SigSpec B = import_sig(conn.second, "_gate");
+				SigBit EQ = module->Eq(NEW_ID, A, B);
+
+				for (auto bit : sigmap({A, B}))
+					data_bit_to_eq_net[bit] = EQ;
+
+				cell_to_eq_nets[cell].append(EQ);
+			}
+		}
+
+		for (auto cell : original->cells())
+		{
+			if (!ct.cell_known(cell->type))
+				continue;
+
+			bool skip_cell = !cell_to_eq_nets.count(cell);
+			pool<SigBit> src_eq_bits;
+
+			for (auto &conn : cell->connections())
+			{
+				if (skip_cell)
+					break;
+
+				if (cell->output(conn.first))
+					continue;
+
+				SigSpec A = import_sig(conn.second, "_gold");
+				SigSpec B = import_sig(conn.second, "_gate");
+
+				for (auto bit : sigmap({A, B})) {
+					if (data_bit_to_eq_net.count(bit))
+						src_eq_bits.insert(data_bit_to_eq_net.at(bit));
+					else
+						skip_cell = true;
+				}
+			}
+
+			if (!skip_cell) {
+				SigSpec antecedent = SigSpec(src_eq_bits);
+				antecedent.sort_and_unify();
+
+				if (GetSize(antecedent) > 1) {
+					if (reduce_db.count(antecedent) == 0)
+						reduce_db[antecedent] = module->ReduceAnd(NEW_ID, antecedent);
+					antecedent = reduce_db.at(antecedent);
+				}
+
+				SigSpec consequent = cell_to_eq_nets.at(cell);
+				consequent.sort_and_unify();
+
+				if (GetSize(consequent) > 1) {
+					if (reduce_db.count(consequent) == 0)
+						reduce_db[consequent] = module->ReduceAnd(NEW_ID, consequent);
+					consequent = reduce_db.at(consequent);
+				}
+
+				if (opts.fwd)
+					module->addAssume(NEW_ID, consequent, antecedent);
+
+				if (opts.bwd)
+				{
+					if (invert_db.count(antecedent) == 0)
+						invert_db[antecedent] = module->Not(NEW_ID, antecedent);
+
+					if (invert_db.count(consequent) == 0)
+						invert_db[consequent] = module->Not(NEW_ID, consequent);
+
+					module->addAssume(NEW_ID, invert_db.at(antecedent), invert_db.at(consequent));
+				}
+			}
+		}
+	}
+};
+
+struct FmcombinePass : public Pass {
+	FmcombinePass() : Pass("fmcombine", "combine two instances of a cell into one") { }
+	void help() YS_OVERRIDE
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    fmcombine [options] module_name gold_cell gate_cell\n");
+		// log("    fmcombine [options] @gold_cell @gate_cell\n");
+		log("\n");
+		log("This pass takes two cells, which are instances of the same module, and replaces\n");
+		log("them with one instance of a special 'combined' module, that effectively\n");
+		log("contains two copies of the original module, plus some formal properties.\n");
+		log("\n");
+		log("This is useful for formal test benches that check what differences in behavior\n");
+		log("a slight difference in input causes in a module.\n");
+		log("\n");
+		log("    -fwd\n");
+		log("        Insert forward hint assumptions into the combined module.\n");
+		log("\n");
+		log("    -bwd\n");
+		log("        Insert backward hint assumptions into the combined module.\n");
+		log("        (Backward hints are logically equivalend to fordward hits, but\n");
+		log("        some solvers are faster with bwd hints, or even both -bwd and -fwd.)\n");
+		log("\n");
+		log("    -nop\n");
+		log("        Don't insert hint assumptions into the combined module.\n");
+		log("        (This should not provide any speedup over the original design, but\n");
+		log("        strangely sometimes it does.)\n");
+		log("\n");
+		log("If none of -fwd, -bwd, and -nop is given, then -fwd is used as default.\n");
+		log("\n");
+	}
+	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
+	{
+		opts_t opts;
+		Module *module = nullptr;
+		Cell *gold_cell = nullptr;
+		Cell *gate_cell = nullptr;
+
+		log_header(design, "Executing FMCOMBINE pass.\n");
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++)
+		{
+			// if (args[argidx] == "-o" && argidx+1 < args.size()) {
+			// 	filename = args[++argidx];
+			// 	continue;
+			// }
+			if (args[argidx] == "-fwd") {
+				opts.fwd = true;
+				continue;
+			}
+			if (args[argidx] == "-bwd") {
+				opts.bwd = true;
+				continue;
+			}
+			if (args[argidx] == "-nop") {
+				opts.nop = true;
+				continue;
+			}
+			break;
+		}
+		if (argidx+2 == args.size())
+		{
+			string gold_name = args[argidx++];
+			string gate_name = args[argidx++];
+			log_cmd_error("fmcombine @gold_cell @gate_cell call style is not implemented yet.");
+		}
+		else if (argidx+3 == args.size())
+		{
+			IdString module_name = RTLIL::escape_id(args[argidx++]);
+			IdString gold_name = RTLIL::escape_id(args[argidx++]);
+			IdString gate_name = RTLIL::escape_id(args[argidx++]);
+
+			module = design->module(module_name);
+			if (module == nullptr)
+				log_cmd_error("Module %s not found.\n", log_id(module_name));
+
+			gold_cell = module->cell(gold_name);
+			if (gold_cell == nullptr)
+				log_cmd_error("Gold cell %s not found in module %s.\n", log_id(gold_name), log_id(module));
+
+			gate_cell = module->cell(gate_name);
+			if (gate_cell == nullptr)
+				log_cmd_error("Gold cell %s not found in module %s.\n", log_id(gate_name), log_id(module));
+		}
+		else
+		{
+			log_cmd_error("Invalid number of arguments.\n");
+		}
+		// extra_args(args, argidx, design);
+
+		if (opts.nop && (opts.fwd || opts.bwd))
+			log_cmd_error("Option -nop can not be combined with -fwd and/or -bwd.\n");
+
+		if (!opts.nop && !opts.fwd && !opts.bwd)
+			opts.fwd = true;
+
+		if (gold_cell->type != gate_cell->type)
+			log_cmd_error("Types of gold and gate cells do not match.\n");
+		if (!gold_cell->parameters.empty())
+			log_cmd_error("Gold cell has unresolved instance parameters.\n");
+		if (!gate_cell->parameters.empty())
+			log_cmd_error("Gold cell has unresolved instance parameters.\n");
+
+		FmcombineWorker worker(design, gold_cell->type, opts);
+		worker.generate();
+		IdString combined_cell_name = module->uniquify(stringf("\\%s_%s", log_id(gold_cell), log_id(gate_cell)));
+
+		Cell *cell = module->addCell(combined_cell_name, worker.combined_type);
+		cell->attributes = gold_cell->attributes;
+		cell->add_strpool_attribute("\\src", gate_cell->get_strpool_attribute("\\src"));
+
+		log("Combining cells %s and %s in module %s into new cell %s.\n", log_id(gold_cell), log_id(gate_cell), log_id(module), log_id(cell));
+
+		for (auto &conn : gold_cell->connections())
+			cell->setPort(conn.first.str() + "_gold", conn.second);
+		module->remove(gold_cell);
+
+		for (auto &conn : gate_cell->connections())
+			cell->setPort(conn.first.str() + "_gate", conn.second);
+		module->remove(gate_cell);
+	}
+} FmcombinePass;
+
+PRIVATE_NAMESPACE_END
diff --git a/passes/sat/mutate.cc b/passes/sat/mutate.cc
new file mode 100644
index 000000000..b53bbfeb2
--- /dev/null
+++ b/passes/sat/mutate.cc
@@ -0,0 +1,988 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *
+ *  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 mutate_t {
+	string mode;
+	pool<string> src;
+	IdString module, cell;
+	IdString port, wire;
+	int portbit = -1;
+	int ctrlbit = -1;
+	int wirebit = -1;
+	bool used = false;
+};
+
+struct mutate_opts_t {
+	int seed = 0;
+	std::string mode;
+	pool<string> src;
+	IdString module, cell, port, wire;
+	int portbit = -1;
+	int ctrlbit = -1;
+	int wirebit = -1;
+
+	IdString ctrl_name;
+	int ctrl_width = -1, ctrl_value = -1;
+
+	bool none = false;
+
+	int pick_cover_prcnt = 80;
+
+	int weight_cover = 500;
+
+	int weight_pq_w = 100;
+	int weight_pq_b = 100;
+	int weight_pq_c = 100;
+	int weight_pq_s = 100;
+
+	int weight_pq_mw = 100;
+	int weight_pq_mb = 100;
+	int weight_pq_mc = 100;
+	int weight_pq_ms = 100;
+};
+
+void database_add(std::vector<mutate_t> &database, const mutate_opts_t &opts, const mutate_t &entry)
+{
+	if (!opts.mode.empty() && opts.mode != entry.mode)
+		return;
+
+	if (!opts.src.empty()) {
+		bool found_match = false;
+		for (auto &s : opts.src) {
+			if (entry.src.count(s))
+				found_match = true;
+		}
+		if (!found_match)
+			return;
+	}
+
+	if (!opts.module.empty() && opts.module != entry.module)
+		return;
+
+	if (!opts.cell.empty() && opts.cell != entry.cell)
+		return;
+
+	if (!opts.port.empty() && opts.port != entry.port)
+		return;
+
+	if (opts.portbit >= 0 && opts.portbit != entry.portbit)
+		return;
+
+	if (opts.ctrlbit >= 0 && opts.ctrlbit != entry.ctrlbit)
+		return;
+
+	if (!opts.wire.empty() && opts.wire != entry.wire)
+		return;
+
+	if (opts.wirebit >= 0 && opts.wirebit != entry.wirebit)
+		return;
+
+	database.push_back(entry);
+}
+
+struct xs128_t
+{
+	uint32_t x = 123456789;
+	uint32_t y = 0, z = 0, w = 0;
+
+	xs128_t(int seed = 0) : w(seed) {
+		next();
+		next();
+		next();
+	}
+
+	void next() {
+		uint32_t t = x ^ (x << 11);
+		x = y, y = z, z = w;
+		w ^= (w >> 19) ^ t ^ (t >> 8);
+	}
+
+	int operator()() {
+		next();
+		return w & 0x3fffffff;
+	}
+
+	int operator()(int n) {
+		if (n < 2)
+			return 0;
+		while (1) {
+			int k = (*this)(), p = k % n;
+			if ((k - p + n) <= 0x40000000)
+				return p;
+		}
+	}
+};
+
+struct coverdb_t
+{
+	dict<string, int> src_db;
+	dict<tuple<IdString, IdString>, int> wire_db;
+	dict<tuple<IdString, IdString, int>, int> wirebit_db;
+
+	void insert(const mutate_t &m) {
+		if (!m.wire.empty()) {
+			wire_db[tuple<IdString, IdString>(m.module, m.wire)] = 0;
+			wirebit_db[tuple<IdString, IdString, int>(m.module, m.wire, m.wirebit)] = 0;
+		}
+		for (auto &s : m.src) {
+			src_db[s] = 0;
+		}
+	}
+
+	void update(const mutate_t &m) {
+		if (!m.wire.empty()) {
+			wire_db.at(tuple<IdString, IdString>(m.module, m.wire))++;
+			wirebit_db.at(tuple<IdString, IdString, int>(m.module, m.wire, m.wirebit))++;
+		}
+		for (auto &s : m.src) {
+			src_db.at(s)++;
+		}
+	}
+
+	int score(const mutate_t &m) {
+		int this_score = m.src.empty() ? 0 : 1;
+		if (!m.wire.empty()) {
+			this_score += wire_db.at(tuple<IdString, IdString>(m.module, m.wire)) ? 0 : 5;
+			this_score += wirebit_db.at(tuple<IdString, IdString, int>(m.module, m.wire, m.wirebit)) ? 0 : 1;
+		}
+		for (auto &s : m.src) {
+			this_score += src_db.at(s) ? 0 : 5;
+		}
+		return this_score;
+	}
+};
+
+struct mutate_queue_t
+{
+	pool<mutate_t*, hash_ptr_ops> db;
+
+	mutate_t *pick(xs128_t &rng, coverdb_t &coverdb, const mutate_opts_t &opts) {
+		mutate_t *m = nullptr;
+		if (rng(100) < opts.pick_cover_prcnt) {
+			vector<mutate_t*> candidates, rmqueue;
+			int best_score = -1;
+			for (auto p : db) {
+				if (p->used) {
+					rmqueue.push_back(p);
+					continue;
+				}
+				int this_score = coverdb.score(*p);
+				if (this_score > best_score) {
+					best_score = this_score;
+					candidates.clear();
+				}
+				if (best_score == this_score)
+					candidates.push_back(p);
+			}
+			for (auto p : rmqueue)
+				db.erase(p);
+			if (!candidates.empty())
+				m = candidates[rng(GetSize(candidates))];
+		}
+		if (m == nullptr) {
+			while (!db.empty()) {
+				int i = rng(GetSize(db));
+				auto it = db.element(i);
+				mutate_t *p = *it;
+				db.erase(it);
+				if (p->used == false) {
+					m = p;
+					break;
+				}
+			}
+		}
+		return m;
+	}
+
+	void add(mutate_t *m) {
+		db.insert(m);
+	}
+};
+
+template <typename K, typename T>
+struct mutate_chain_queue_t
+{
+	dict<K, T> db;
+
+	mutate_t *pick(xs128_t &rng, coverdb_t &coverdb, const mutate_opts_t &opts) {
+		while (!db.empty()) {
+			int i = rng(GetSize(db));
+			auto it = db.element(i);
+			mutate_t *m = it->second.pick(rng, coverdb, opts);
+			if (m != nullptr)
+				return m;
+			db.erase(it);
+		}
+		return nullptr;
+	}
+
+	template<typename... Args>
+	void add(mutate_t *m, K key, Args... args) {
+		db[key].add(m, args...);
+	}
+};
+
+template <typename K, typename T>
+struct mutate_once_queue_t
+{
+	dict<K, T> db;
+
+	mutate_t *pick(xs128_t &rng, coverdb_t &coverdb, const mutate_opts_t &opts) {
+		while (!db.empty()) {
+			int i = rng(GetSize(db));
+			auto it = db.element(i);
+			mutate_t *m = it->second.pick(rng, coverdb, opts);
+			db.erase(it);
+			if (m != nullptr)
+				return m;
+		}
+		return nullptr;
+	}
+
+	template<typename... Args>
+	void add(mutate_t *m, K key, Args... args) {
+		db[key].add(m, args...);
+	}
+};
+
+void database_reduce(std::vector<mutate_t> &database, const mutate_opts_t &opts, int N, xs128_t &rng)
+{
+	std::vector<mutate_t> new_database;
+	coverdb_t coverdb;
+
+	int total_weight = opts.weight_cover + opts.weight_pq_w + opts.weight_pq_b + opts.weight_pq_c + opts.weight_pq_s;
+	total_weight += opts.weight_pq_mw + opts.weight_pq_mb + opts.weight_pq_mc + opts.weight_pq_ms;
+
+	if (N >= GetSize(database))
+		return;
+
+	mutate_once_queue_t<tuple<IdString, IdString>, mutate_queue_t> primary_queue_wire;
+	mutate_once_queue_t<tuple<IdString, IdString, int>, mutate_queue_t> primary_queue_bit;
+	mutate_once_queue_t<tuple<IdString, IdString>, mutate_queue_t> primary_queue_cell;
+	mutate_once_queue_t<string, mutate_queue_t> primary_queue_src;
+
+	mutate_chain_queue_t<IdString, mutate_once_queue_t<IdString, mutate_queue_t>> primary_queue_module_wire;
+	mutate_chain_queue_t<IdString, mutate_once_queue_t<pair<IdString, int>, mutate_queue_t>> primary_queue_module_bit;
+	mutate_chain_queue_t<IdString, mutate_once_queue_t<IdString, mutate_queue_t>> primary_queue_module_cell;
+	mutate_chain_queue_t<IdString, mutate_once_queue_t<string, mutate_queue_t>> primary_queue_module_src;
+
+	for (auto &m : database)
+	{
+		coverdb.insert(m);
+
+		if (!m.wire.empty()) {
+			primary_queue_wire.add(&m, tuple<IdString, IdString>(m.module, m.wire));
+			primary_queue_bit.add(&m, tuple<IdString, IdString, int>(m.module, m.wire, m.wirebit));
+			primary_queue_module_wire.add(&m, m.module, m.wire);
+			primary_queue_module_bit.add(&m, m.module, pair<IdString, int>(m.wire, m.wirebit));
+		}
+
+		primary_queue_cell.add(&m, tuple<IdString, IdString>(m.module, m.cell));
+		primary_queue_module_cell.add(&m, m.module, m.cell);
+
+		for (auto &s : m.src) {
+			primary_queue_src.add(&m, s);
+			primary_queue_module_src.add(&m, m.module, s);
+		}
+	}
+
+	vector<mutate_t*> cover_candidates;
+	int best_cover_score = -1;
+	bool skip_cover = false;
+
+	while (GetSize(new_database) < N)
+	{
+		int k = rng(total_weight);
+
+		k -= opts.weight_cover;
+		if (k < 0) {
+			while (!skip_cover) {
+				if (cover_candidates.empty()) {
+					best_cover_score = -1;
+					for (auto &m : database) {
+						if (m.used || m.src.empty())
+							continue;
+						int this_score = -1;
+						for (auto &s : m.src) {
+							if (this_score == -1 || this_score > coverdb.src_db.at(s))
+								this_score = coverdb.src_db.at(s);
+						}
+						log_assert(this_score != -1);
+						if (best_cover_score == -1 || this_score < best_cover_score) {
+							cover_candidates.clear();
+							best_cover_score = this_score;
+						}
+						if (best_cover_score == this_score)
+							cover_candidates.push_back(&m);
+					}
+					if (best_cover_score == -1) {
+						skip_cover = true;
+						break;
+					}
+				}
+
+				mutate_t *m = nullptr;
+				while (!cover_candidates.empty())
+				{
+					int idx = rng(GetSize(cover_candidates));
+					mutate_t *p = cover_candidates[idx];
+					cover_candidates[idx] = cover_candidates.back();
+					cover_candidates.pop_back();
+
+					if (p->used)
+						continue;
+
+					int this_score = -1;
+					for (auto &s : p->src) {
+						if (this_score == -1 || this_score > coverdb.src_db.at(s))
+							this_score = coverdb.src_db.at(s);
+					}
+
+					if (this_score != best_cover_score)
+						continue;
+
+					m = p;
+					break;
+				}
+
+				if (m != nullptr) {
+					m->used = true;
+					coverdb.update(*m);
+					new_database.push_back(*m);
+					break;
+				}
+			}
+			continue;
+		}
+
+#define X(__wght, __queue)                               \
+    k -= __wght;                                         \
+    if (k < 0) {                                         \
+      mutate_t *m = __queue.pick(rng, coverdb, opts);    \
+      if (m != nullptr) {                                \
+        m->used = true;                                  \
+        coverdb.update(*m);                              \
+        new_database.push_back(*m);                      \
+      };                                                 \
+      continue;                                          \
+    }
+
+		X(opts.weight_pq_w, primary_queue_wire)
+		X(opts.weight_pq_b, primary_queue_bit)
+		X(opts.weight_pq_c, primary_queue_cell)
+		X(opts.weight_pq_s, primary_queue_src)
+
+		X(opts.weight_pq_mw, primary_queue_module_wire)
+		X(opts.weight_pq_mb, primary_queue_module_bit)
+		X(opts.weight_pq_mc, primary_queue_module_cell)
+		X(opts.weight_pq_ms, primary_queue_module_src)
+#undef X
+	}
+
+	std::swap(new_database, database);
+
+	int covered_src_cnt = 0;
+	int covered_wire_cnt = 0;
+	int covered_wirebit_cnt = 0;
+
+	for (auto &it : coverdb.src_db)
+		if (it.second)
+			covered_src_cnt++;
+
+	for (auto &it : coverdb.wire_db)
+		if (it.second)
+			covered_wire_cnt++;
+
+	for (auto &it : coverdb.wirebit_db)
+		if (it.second)
+			covered_wirebit_cnt++;
+
+	log("Covered %d/%d src attributes (%.2f%%).\n", covered_src_cnt, GetSize(coverdb.src_db), 100.0 * covered_src_cnt / GetSize(coverdb.src_db));
+	log("Covered %d/%d wires (%.2f%%).\n", covered_wire_cnt, GetSize(coverdb.wire_db), 100.0 * covered_wire_cnt / GetSize(coverdb.wire_db));
+	log("Covered %d/%d wire bits (%.2f%%).\n", covered_wirebit_cnt, GetSize(coverdb.wirebit_db), 100.0 * covered_wirebit_cnt / GetSize(coverdb.wirebit_db));
+}
+
+void mutate_list(Design *design, const mutate_opts_t &opts, const string &filename, const string &srcsfile, int N)
+{
+	pool<string> sources;
+	std::vector<mutate_t> database;
+	xs128_t rng(opts.seed);
+
+	for (auto module : design->selected_modules())
+	{
+		if (!opts.module.empty() && module->name != opts.module)
+			continue;
+
+		SigMap sigmap(module);
+		dict<SigBit, int> bit_user_cnt;
+
+		for (auto wire : module->wires()) {
+			if (wire->name[0] == '\\' && wire->attributes.count("\\src"))
+				sigmap.add(wire);
+		}
+
+		for (auto cell : module->cells()) {
+			for (auto &conn : cell->connections()) {
+				if (cell->output(conn.first))
+					continue;
+				for (auto bit : sigmap(conn.second))
+					bit_user_cnt[bit]++;
+			}
+		}
+
+		for (auto wire : module->selected_wires())
+		{
+			for (SigBit bit : SigSpec(wire))
+			{
+				SigBit sigbit = sigmap(bit);
+
+				if (bit.wire == nullptr || sigbit.wire == nullptr)
+					continue;
+
+				if (!bit.wire->port_id != !sigbit.wire->port_id) {
+					if (bit.wire->port_id)
+						sigmap.add(bit);
+					continue;
+				}
+
+				if (!bit.wire->name[0] != !sigbit.wire->name[0]) {
+					if (bit.wire->name[0] == '\\')
+						sigmap.add(bit);
+					continue;
+				}
+			}
+		}
+
+		for (auto cell : module->selected_cells())
+		{
+			if (!opts.cell.empty() && cell->name != opts.cell)
+				continue;
+
+			for (auto &conn : cell->connections())
+			{
+				for (int i = 0; i < GetSize(conn.second); i++) {
+					mutate_t entry;
+					entry.module = module->name;
+					entry.cell = cell->name;
+					entry.port = conn.first;
+					entry.portbit = i;
+
+					for (auto &s : cell->get_strpool_attribute("\\src"))
+						entry.src.insert(s);
+
+					SigBit bit = sigmap(conn.second[i]);
+					if (bit.wire && bit.wire->name[0] == '\\' && (cell->output(conn.first) || bit_user_cnt[bit] == 1)) {
+						for (auto &s : bit.wire->get_strpool_attribute("\\src"))
+							entry.src.insert(s);
+						entry.wire = bit.wire->name;
+						entry.wirebit = bit.offset;
+					}
+
+					if (!srcsfile.empty())
+						sources.insert(entry.src.begin(), entry.src.end());
+
+					entry.mode = "inv";
+					database_add(database, opts, entry);
+
+					entry.mode = "const0";
+					database_add(database, opts, entry);
+
+					entry.mode = "const1";
+					database_add(database, opts, entry);
+
+					entry.mode = "cnot0";
+					entry.ctrlbit = rng(GetSize(conn.second));
+					if (entry.ctrlbit != entry.portbit && conn.second[entry.ctrlbit].wire)
+						database_add(database, opts, entry);
+
+					entry.mode = "cnot1";
+					entry.ctrlbit = rng(GetSize(conn.second));
+					if (entry.ctrlbit != entry.portbit && conn.second[entry.ctrlbit].wire)
+						database_add(database, opts, entry);
+				}
+			}
+		}
+	}
+
+	log("Raw database size: %d\n", GetSize(database));
+	if (N != 0) {
+		database_reduce(database, opts, opts.none ? N-1 : N, rng);
+		log("Reduced database size: %d\n", GetSize(database));
+	}
+
+	if (!srcsfile.empty()) {
+		std::ofstream sout;
+		sout.open(srcsfile, std::ios::out | std::ios::trunc);
+		if (!sout.is_open())
+			log_error("Could not open file \"%s\" with write access.\n", srcsfile.c_str());
+		sources.sort();
+		for (auto &s : sources)
+			sout << s << std::endl;
+	}
+
+	std::ofstream fout;
+
+	if (!filename.empty()) {
+		fout.open(filename, std::ios::out | std::ios::trunc);
+		if (!fout.is_open())
+			log_error("Could not open file \"%s\" with write access.\n", filename.c_str());
+	}
+
+	int ctrl_value = opts.ctrl_value;
+
+	if (opts.none) {
+		string str = "mutate";
+		if (!opts.ctrl_name.empty())
+			str += stringf(" -ctrl %s %d %d", log_id(opts.ctrl_name), opts.ctrl_width, ctrl_value++);
+		str += " -mode none";
+		if (filename.empty())
+			log("%s\n", str.c_str());
+		else
+			fout << str << std::endl;
+	}
+
+	for (auto &entry : database) {
+		string str = "mutate";
+		if (!opts.ctrl_name.empty())
+			str += stringf(" -ctrl %s %d %d", log_id(opts.ctrl_name), opts.ctrl_width, ctrl_value++);
+		str += stringf(" -mode %s", entry.mode.c_str());
+		if (!entry.module.empty())
+			str += stringf(" -module %s", log_id(entry.module));
+		if (!entry.cell.empty())
+			str += stringf(" -cell %s", log_id(entry.cell));
+		if (!entry.port.empty())
+			str += stringf(" -port %s", log_id(entry.port));
+		if (entry.portbit >= 0)
+			str += stringf(" -portbit %d", entry.portbit);
+		if (entry.ctrlbit >= 0)
+			str += stringf(" -ctrlbit %d", entry.ctrlbit);
+		if (!entry.wire.empty())
+			str += stringf(" -wire %s", log_id(entry.wire));
+		if (entry.wirebit >= 0)
+			str += stringf(" -wirebit %d", entry.wirebit);
+		for (auto &s : entry.src)
+			str += stringf(" -src %s", s.c_str());
+		if (filename.empty())
+			log("%s\n", str.c_str());
+		else
+			fout << str << std::endl;
+	}
+}
+
+SigSpec mutate_ctrl_sig(Module *module, IdString name, int width)
+{
+	Wire *ctrl_wire = module->wire(name);
+
+	if (ctrl_wire == nullptr)
+	{
+		log("Adding ctrl port %s to module %s.\n", log_id(name), log_id(module));
+
+		ctrl_wire = module->addWire(name, width);
+		ctrl_wire->port_input = true;
+		module->fixup_ports();
+
+		for (auto mod : module->design->modules())
+		for (auto cell : mod->cells())
+		{
+			if (cell->type != module->name)
+				continue;
+
+			SigSpec ctrl = mutate_ctrl_sig(mod, name, width);
+
+			log("Connecting ctrl port to cell %s in module %s.\n", log_id(cell), log_id(mod));
+			cell->setPort(name, ctrl);
+		}
+	}
+
+	log_assert(GetSize(ctrl_wire) == width);
+	return ctrl_wire;
+}
+
+SigBit mutate_ctrl(Module *module, const mutate_opts_t &opts)
+{
+	if (opts.ctrl_name.empty())
+		return State::S1;
+
+	SigSpec sig = mutate_ctrl_sig(module, opts.ctrl_name, opts.ctrl_width);
+	return module->Eq(NEW_ID, sig, Const(opts.ctrl_value, GetSize(sig)));
+}
+
+SigSpec mutate_ctrl_mux(Module *module, const mutate_opts_t &opts, SigSpec unchanged_sig, SigSpec changed_sig)
+{
+	SigBit ctrl_bit = mutate_ctrl(module, opts);
+	if (ctrl_bit == State::S0)
+		return unchanged_sig;
+	if (ctrl_bit == State::S1)
+		return changed_sig;
+	return module->Mux(NEW_ID, unchanged_sig, changed_sig, ctrl_bit);
+}
+
+void mutate_inv(Design *design, const mutate_opts_t &opts)
+{
+	Module *module = design->module(opts.module);
+	Cell *cell = module->cell(opts.cell);
+
+	SigBit bit = cell->getPort(opts.port)[opts.portbit];
+	SigBit inbit, outbit;
+
+	if (cell->input(opts.port))
+	{
+		log("Add input inverter at %s.%s.%s[%d].\n", log_id(module), log_id(cell), log_id(opts.port), opts.portbit);
+		SigBit outbit = module->Not(NEW_ID, bit);
+		bit = mutate_ctrl_mux(module, opts, bit, outbit);
+	}
+	else
+	{
+		log("Add output inverter at %s.%s.%s[%d].\n", log_id(module), log_id(cell), log_id(opts.port), opts.portbit);
+		SigBit inbit = module->addWire(NEW_ID);
+		SigBit outbit = module->Not(NEW_ID, inbit);
+		module->connect(bit, mutate_ctrl_mux(module, opts, inbit, outbit));
+		bit = inbit;
+	}
+
+	SigSpec s = cell->getPort(opts.port);
+	s[opts.portbit] = bit;
+	cell->setPort(opts.port, s);
+}
+
+void mutate_const(Design *design, const mutate_opts_t &opts, bool one)
+{
+	Module *module = design->module(opts.module);
+	Cell *cell = module->cell(opts.cell);
+
+	SigBit bit = cell->getPort(opts.port)[opts.portbit];
+	SigBit inbit, outbit;
+
+	if (cell->input(opts.port))
+	{
+		log("Add input constant %d at %s.%s.%s[%d].\n", one ? 1 : 0, log_id(module), log_id(cell), log_id(opts.port), opts.portbit);
+		SigBit outbit = one ? State::S1 : State::S0;
+		bit = mutate_ctrl_mux(module, opts, bit, outbit);
+	}
+	else
+	{
+		log("Add output constant %d at %s.%s.%s[%d].\n", one ? 1 : 0, log_id(module), log_id(cell), log_id(opts.port), opts.portbit);
+		SigBit inbit = module->addWire(NEW_ID);
+		SigBit outbit = one ? State::S1 : State::S0;
+		module->connect(bit, mutate_ctrl_mux(module, opts, inbit, outbit));
+		bit = inbit;
+	}
+
+	SigSpec s = cell->getPort(opts.port);
+	s[opts.portbit] = bit;
+	cell->setPort(opts.port, s);
+}
+
+void mutate_cnot(Design *design, const mutate_opts_t &opts, bool one)
+{
+	Module *module = design->module(opts.module);
+	Cell *cell = module->cell(opts.cell);
+
+	SigBit bit = cell->getPort(opts.port)[opts.portbit];
+	SigBit ctrl = cell->getPort(opts.port)[opts.ctrlbit];
+	SigBit inbit, outbit;
+
+	if (cell->input(opts.port))
+	{
+		log("Add input cnot%d at %s.%s.%s[%d,%d].\n", one ? 1 : 0, log_id(module), log_id(cell), log_id(opts.port), opts.portbit, opts.ctrlbit);
+		SigBit outbit = one ? module->Xor(NEW_ID, bit, ctrl) : module->Xnor(NEW_ID, bit, ctrl);
+		bit = mutate_ctrl_mux(module, opts, bit, outbit);
+	}
+	else
+	{
+		log("Add output cnot%d at %s.%s.%s[%d,%d].\n", one ? 1 : 0, log_id(module), log_id(cell), log_id(opts.port), opts.portbit, opts.ctrlbit);
+		SigBit inbit = module->addWire(NEW_ID);
+		SigBit outbit = one ? module->Xor(NEW_ID, inbit, ctrl) : module->Xnor(NEW_ID, inbit, ctrl);
+		module->connect(bit, mutate_ctrl_mux(module, opts, inbit, outbit));
+		bit = inbit;
+	}
+
+	SigSpec s = cell->getPort(opts.port);
+	s[opts.portbit] = bit;
+	cell->setPort(opts.port, s);
+}
+
+struct MutatePass : public Pass {
+	MutatePass() : Pass("mutate", "generate or apply design mutations") { }
+	void help() YS_OVERRIDE
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    mutate -list N [options] [selection]\n");
+		log("\n");
+		log("Create a list of N mutations using an even sampling.\n");
+		log("\n");
+		log("    -o filename\n");
+		log("        Write list to this file instead of console output\n");
+		log("\n");
+		log("    -s filename\n");
+		log("        Write a list of all src tags found in the design to the specified file\n");
+		log("\n");
+		log("    -seed N\n");
+		log("        RNG seed for selecting mutations\n");
+		log("\n");
+		log("    -none\n");
+		log("        Include a \"none\" mutation in the output\n");
+		log("\n");
+		log("    -ctrl name width value\n");
+		log("        Add -ctrl options to the output. Use 'value' for first mutation, then\n");
+		log("        simply count up from there.\n");
+		log("\n");
+		log("    -mode name\n");
+		log("    -module name\n");
+		log("    -cell name\n");
+		log("    -port name\n");
+		log("    -portbit int\n");
+		log("    -ctrlbit int\n");
+		log("    -wire name\n");
+		log("    -wirebit int\n");
+		log("    -src string\n");
+		log("        Filter list of mutation candidates to those matching\n");
+		log("        the given parameters.\n");
+		log("\n");
+		log("    -cfg option int\n");
+		log("        Set a configuration option. Options available:\n");
+		log("          weight_pq_w weight_pq_b weight_pq_c weight_pq_s\n");
+		log("          weight_pq_mw weight_pq_mb weight_pq_mc weight_pq_ms\n");
+		log("          weight_cover pick_cover_prcnt\n");
+		log("\n");
+		log("\n");
+		log("    mutate -mode MODE [options]\n");
+		log("\n");
+		log("Apply the given mutation.\n");
+		log("\n");
+		log("    -ctrl name width value\n");
+		log("        Add a control signal with the given name and width. The mutation is\n");
+		log("        activated if the control signal equals the given value.\n");
+		log("\n");
+		log("    -module name\n");
+		log("    -cell name\n");
+		log("    -port name\n");
+		log("    -portbit int\n");
+		log("    -ctrlbit int\n");
+		log("        Mutation parameters, as generated by 'mutate -list N'.\n");
+		log("\n");
+		log("    -wire name\n");
+		log("    -wirebit int\n");
+		log("    -src string\n");
+		log("        Ignored. (They are generated by -list for documentation purposes.)\n");
+		log("\n");
+	}
+	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
+	{
+		mutate_opts_t opts;
+		string filename;
+		string srcsfile;
+		int N = -1;
+
+		log_header(design, "Executing MUTATE pass.\n");
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++)
+		{
+			if (args[argidx] == "-list" && argidx+1 < args.size()) {
+				N = atoi(args[++argidx].c_str());
+				continue;
+			}
+			if (args[argidx] == "-o" && argidx+1 < args.size()) {
+				filename = args[++argidx];
+				continue;
+			}
+			if (args[argidx] == "-s" && argidx+1 < args.size()) {
+				srcsfile = args[++argidx];
+				continue;
+			}
+			if (args[argidx] == "-seed" && argidx+1 < args.size()) {
+				opts.seed = atoi(args[++argidx].c_str());
+				continue;
+			}
+			if (args[argidx] == "-none") {
+				opts.none = true;
+				continue;
+			}
+			if (args[argidx] == "-mode" && argidx+1 < args.size()) {
+				opts.mode = args[++argidx];
+				continue;
+			}
+			if (args[argidx] == "-ctrl" && argidx+3 < args.size()) {
+				opts.ctrl_name = RTLIL::escape_id(args[++argidx]);
+				opts.ctrl_width = atoi(args[++argidx].c_str());
+				opts.ctrl_value = atoi(args[++argidx].c_str());
+				continue;
+			}
+			if (args[argidx] == "-module" && argidx+1 < args.size()) {
+				opts.module = RTLIL::escape_id(args[++argidx]);
+				continue;
+			}
+			if (args[argidx] == "-cell" && argidx+1 < args.size()) {
+				opts.cell = RTLIL::escape_id(args[++argidx]);
+				continue;
+			}
+			if (args[argidx] == "-port" && argidx+1 < args.size()) {
+				opts.port = RTLIL::escape_id(args[++argidx]);
+				continue;
+			}
+			if (args[argidx] == "-portbit" && argidx+1 < args.size()) {
+				opts.portbit = atoi(args[++argidx].c_str());
+				continue;
+			}
+			if (args[argidx] == "-ctrlbit" && argidx+1 < args.size()) {
+				opts.ctrlbit = atoi(args[++argidx].c_str());
+				continue;
+			}
+			if (args[argidx] == "-wire" && argidx+1 < args.size()) {
+				opts.wire = RTLIL::escape_id(args[++argidx]);
+				continue;
+			}
+			if (args[argidx] == "-wirebit" && argidx+1 < args.size()) {
+				opts.wirebit = atoi(args[++argidx].c_str());
+				continue;
+			}
+			if (args[argidx] == "-src" && argidx+1 < args.size()) {
+				opts.src.insert(args[++argidx]);
+				continue;
+			}
+			if (args[argidx] == "-cfg" && argidx+2 < args.size()) {
+				if (args[argidx+1] == "pick_cover_prcnt") {
+					opts.pick_cover_prcnt = atoi(args[argidx+2].c_str());
+					argidx += 2;
+					continue;
+				}
+				if (args[argidx+1] == "weight_cover") {
+					opts.weight_cover = atoi(args[argidx+2].c_str());
+					argidx += 2;
+					continue;
+				}
+				if (args[argidx+1] == "weight_pq_w") {
+					opts.weight_pq_w = atoi(args[argidx+2].c_str());
+					argidx += 2;
+					continue;
+				}
+				if (args[argidx+1] == "weight_pq_b") {
+					opts.weight_pq_b = atoi(args[argidx+2].c_str());
+					argidx += 2;
+					continue;
+				}
+				if (args[argidx+1] == "weight_pq_c") {
+					opts.weight_pq_c = atoi(args[argidx+2].c_str());
+					argidx += 2;
+					continue;
+				}
+				if (args[argidx+1] == "weight_pq_s") {
+					opts.weight_pq_s = atoi(args[argidx+2].c_str());
+					argidx += 2;
+					continue;
+				}
+				if (args[argidx+1] == "weight_pq_mw") {
+					opts.weight_pq_mw = atoi(args[argidx+2].c_str());
+					argidx += 2;
+					continue;
+				}
+				if (args[argidx+1] == "weight_pq_mb") {
+					opts.weight_pq_mb = atoi(args[argidx+2].c_str());
+					argidx += 2;
+					continue;
+				}
+				if (args[argidx+1] == "weight_pq_mc") {
+					opts.weight_pq_mc = atoi(args[argidx+2].c_str());
+					argidx += 2;
+					continue;
+				}
+				if (args[argidx+1] == "weight_pq_ms") {
+					opts.weight_pq_ms = atoi(args[argidx+2].c_str());
+					argidx += 2;
+					continue;
+				}
+			}
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		if (N >= 0) {
+			mutate_list(design, opts, filename, srcsfile, N);
+			return;
+		}
+
+		if (opts.mode == "none") {
+			if (!opts.ctrl_name.empty()) {
+				Module *topmod = opts.module.empty() ? design->top_module() : design->module(opts.module);
+				if (topmod)
+					mutate_ctrl_sig(topmod, opts.ctrl_name, opts.ctrl_width);
+			}
+			return;
+		}
+
+		if (opts.module.empty())
+			log_cmd_error("Missing -module argument.\n");
+
+		Module *module = design->module(opts.module);
+		if (module == nullptr)
+			log_cmd_error("Module %s not found.\n", log_id(opts.module));
+
+		if (opts.cell.empty())
+			log_cmd_error("Missing -cell argument.\n");
+
+		Cell *cell = module->cell(opts.cell);
+		if (cell == nullptr)
+			log_cmd_error("Cell %s not found in module %s.\n", log_id(opts.cell), log_id(opts.module));
+
+		if (opts.port.empty())
+			log_cmd_error("Missing -port argument.\n");
+
+		if (!cell->hasPort(opts.port))
+			log_cmd_error("Port %s not found on cell %s.%s.\n", log_id(opts.port), log_id(opts.module), log_id(opts.cell));
+
+		if (opts.portbit < 0)
+			log_cmd_error("Missing -portbit argument.\n");
+
+		if (GetSize(cell->getPort(opts.port)) <= opts.portbit)
+			log_cmd_error("Out-of-range -portbit argument for port %s on cell %s.%s.\n", log_id(opts.port), log_id(opts.module), log_id(opts.cell));
+
+		if (opts.mode == "inv") {
+			mutate_inv(design, opts);
+			return;
+		}
+
+		if (opts.mode == "const0" || opts.mode == "const1") {
+			mutate_const(design, opts, opts.mode == "const1");
+			return;
+		}
+
+		if (opts.ctrlbit < 0)
+			log_cmd_error("Missing -ctrlbit argument.\n");
+
+		if (GetSize(cell->getPort(opts.port)) <= opts.ctrlbit)
+			log_cmd_error("Out-of-range -ctrlbit argument for port %s on cell %s.%s.\n", log_id(opts.port), log_id(opts.module), log_id(opts.cell));
+
+		if (opts.mode == "cnot0" || opts.mode == "cnot1") {
+			mutate_cnot(design, opts, opts.mode == "cnot1");
+			return;
+		}
+
+		log_cmd_error("Invalid mode: %s\n", opts.mode.c_str());
+	}
+} MutatePass;
+
+PRIVATE_NAMESPACE_END
diff --git a/passes/sat/supercover.cc b/passes/sat/supercover.cc
new file mode 100644
index 000000000..ba44f02d8
--- /dev/null
+++ b/passes/sat/supercover.cc
@@ -0,0 +1,92 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *
+ *  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 SupercoverPass : public Pass {
+	SupercoverPass() : Pass("supercover", "add hi/lo cover cells for each wire bit") { }
+	void help() YS_OVERRIDE
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    supercover [options] [selection]\n");
+		log("\n");
+		log("This command adds two cover cells for each bit of each selected wire, one\n");
+		log("checking for a hi signal level and one checking for lo level.\n");
+		log("\n");
+	}
+	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
+	{
+		// bool flag_noinit = false;
+
+		log_header(design, "Executing SUPERCOVER pass.\n");
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++)
+		{
+			// if (args[argidx] == "-noinit") {
+			// 	flag_noinit = true;
+			// 	continue;
+			// }
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		for (auto module : design->selected_modules())
+		{
+			SigMap sigmap(module);
+			pool<SigBit> handled_bits;
+
+			int cnt_wire = 0, cnt_bits = 0;
+			log("Adding cover cells to module %s.\n", log_id(module));
+			for (auto wire : module->selected_wires())
+			{
+				bool counted_wire = false;
+				std::string src = wire->get_src_attribute();
+
+				for (auto bit : sigmap(SigSpec(wire)))
+				{
+					if (bit.wire == nullptr)
+						continue;
+
+					if (handled_bits.count(bit))
+						continue;
+
+					SigSpec inv = module->Not(NEW_ID, bit);
+					module->addCover(NEW_ID, bit, State::S1, src);
+					module->addCover(NEW_ID, inv, State::S1, src);
+
+					handled_bits.insert(bit);
+					if (!counted_wire) {
+						counted_wire = false;
+						cnt_wire++;
+					}
+					cnt_bits++;
+				}
+			}
+			log("  added cover cells to %d wires, %d bits.\n", cnt_wire, cnt_bits);
+		}
+	}
+} SupercoverPass;
+
+PRIVATE_NAMESPACE_END
diff --git a/passes/techmap/libparse.cc b/passes/techmap/libparse.cc
index 3927a657b..991cc4498 100644
--- a/passes/techmap/libparse.cc
+++ b/passes/techmap/libparse.cc
@@ -24,6 +24,7 @@
 #include <istream>
 #include <fstream>
 #include <iostream>
+#include <sstream>
 
 #ifndef FILTERLIB
 #include "kernel/log.h"
@@ -86,15 +87,17 @@ int LibertyParser::lexer(std::string &str)
 {
 	int c;
 
+	// eat whitespace
 	do {
 		c = f.get();
 	} while (c == ' ' || c == '\t' || c == '\r');
 
-	if (('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || ('0' <= c && c <= '9') || c == '_' || c == '-' || c == '+' || c == '.' || c == '[' || c == ']') {
+	// search for identifiers, numbers, plus or minus.
+	if (('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || ('0' <= c && c <= '9') || c == '_' || c == '-' || c == '+' || c == '.') {
 		str = c;
 		while (1) {
 			c = f.get();
-			if (('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || ('0' <= c && c <= '9') || c == '_' || c == '-' || c == '+' || c == '.' || c == '[' || c == ']')
+			if (('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || ('0' <= c && c <= '9') || c == '_' || c == '-' || c == '+' || c == '.')
 				str += c;
 			else
 				break;
@@ -111,6 +114,8 @@ int LibertyParser::lexer(std::string &str)
 		}
 	}
 
+	// if it wasn't an identifer, number of array range,
+	// maybe it's a string?
 	if (c == '"') {
 		str = "";
 		while (1) {
@@ -125,9 +130,10 @@ int LibertyParser::lexer(std::string &str)
 		return 'v';
 	}
 
+	// if it wasn't a string, perhaps it's a comment or a forward slash?
 	if (c == '/') {
 		c = f.get();
-		if (c == '*') {
+		if (c == '*') {         // start of '/*' block comment
 			int last_c = 0;
 			while (c > 0 && (last_c != '*' || c != '/')) {
 				last_c = c;
@@ -136,7 +142,7 @@ int LibertyParser::lexer(std::string &str)
 					line++;
 			}
 			return lexer(str);
-		} else if (c == '/') {
+		} else if (c == '/') {  // start of '//' line comment
 			while (c > 0 && c != '\n')
 				c = f.get();
 			line++;
@@ -144,24 +150,31 @@ int LibertyParser::lexer(std::string &str)
 		}
 		f.unget();
 		// fprintf(stderr, "LEX: char >>/<<\n");
-		return '/';
+		return '/';             // a single '/' charater.
 	}
 
+	// check for a backslash
 	if (c == '\\') {
-		c = f.get();
+		c = f.get();		
 		if (c == '\r')
 			c = f.get();
-		if (c == '\n')
+		if (c == '\n') {
+			line++;
 			return lexer(str);
+		}
 		f.unget();
 		return '\\';
 	}
 
+	// check for a new line
 	if (c == '\n') {
 		line++;
 		return 'n';
 	}
 
+	// anything else, such as ';' will get passed
+	// through as literal items.
+
 	// if (c >= 32 && c < 255)
 	// 	fprintf(stderr, "LEX: char >>%c<<\n", c);
 	// else
@@ -175,14 +188,39 @@ LibertyAst *LibertyParser::parse()
 
 	int tok = lexer(str);
 
-	while (tok == 'n')
+	// there are liberty files in the wild that
+	// have superfluous ';' at the end of
+	// a  { ... }. We simply ignore a ';' here.
+	// and get to the next statement.
+
+	while ((tok == 'n') || (tok == ';'))
 		tok = lexer(str);
 
 	if (tok == '}' || tok < 0)
 		return NULL;
 
-	if (tok != 'v')
-		error();
+	if (tok != 'v') {
+		std::string eReport;
+		switch(tok)
+		{
+		case 'n':
+			error("Unexpected newline.");
+			break;
+		case '[':
+		case ']':
+		case '}':
+		case '{':
+		case '\"':
+		case ':':
+			eReport = "Unexpected '";
+			eReport += static_cast<char>(tok);
+			eReport += "'.";
+			error(eReport);
+			break;
+		default:
+			error();
+		}
+	}
 
 	LibertyAst *ast = new LibertyAst;
 	ast->id = str;
@@ -191,12 +229,11 @@ LibertyAst *LibertyParser::parse()
 	{
 		tok = lexer(str);
 
-		if (tok == ';')
+		// allow both ';' and new lines to 
+		// terminate a statement.
+		if ((tok == ';') || (tok == 'n'))
 			break;
 
-		if (tok == 'n')
-			continue;
-
 		if (tok == ':' && ast->value.empty()) {
 			tok = lexer(ast->value);
 			if (tok != 'v')
@@ -210,7 +247,12 @@ LibertyAst *LibertyParser::parse()
 				ast->value += str;
 				tok = lexer(str);
 			}
-			if (tok == ';')
+			
+			// In a liberty file, all key : value pairs should end in ';'
+			// However, there are some liberty files in the wild that
+			// just have a newline. We'll be kind and accept a newline
+			// instead of the ';' too..
+			if ((tok == ';') || (tok == 'n'))
 				break;
 			else
 				error();
@@ -225,8 +267,70 @@ LibertyAst *LibertyParser::parse()
 					continue;
 				if (tok == ')')
 					break;
-				if (tok != 'v')
-					error();
+				
+				// FIXME: the AST needs to be extended to store
+				//        these vector ranges.
+				if (tok == '[')
+				{
+					// parse vector range [A] or [A:B]
+					std::string arg;
+					tok = lexer(arg);
+					if (tok != 'v')
+					{
+						// expected a vector array index
+						error("Expected a number.");
+					}
+					else
+					{
+						// fixme: check for number A
+					}
+					tok = lexer(arg);
+					// optionally check for : in case of [A:B]
+					// if it isn't we just expect ']'
+					// as we have [A]
+					if (tok == ':')
+					{
+						tok = lexer(arg);
+						if (tok != 'v')
+						{
+							// expected a vector array index
+							error("Expected a number.");
+						}
+						else
+						{
+							// fixme: check for number B
+							tok = lexer(arg);                            
+						}
+					}
+					// expect a closing bracket of array range
+					if (tok != ']')
+					{
+						error("Expected ']' on array range.");
+					}
+					continue;           
+				}
+				if (tok != 'v') {
+					std::string eReport;
+					switch(tok)
+					{
+					case 'n':
+						error("Unexpected newline.");
+						break;
+					case '[':
+					case ']':
+					case '}':
+					case '{':
+					case '\"':
+					case ':':
+						eReport = "Unexpected '";
+						eReport += static_cast<char>(tok);
+						eReport += "'.";
+						error(eReport);
+						break;
+					default:
+						error();
+					}
+				}
 				ast->args.push_back(arg);
 			}
 			continue;
@@ -255,6 +359,14 @@ void LibertyParser::error()
 	log_error("Syntax error in liberty file on line %d.\n", line);
 }
 
+void LibertyParser::error(const std::string &str)
+{
+	std::stringstream ss;
+	ss << "Syntax error in liberty file on line " << line << ".\n";
+	ss << "  " << str << "\n";
+	log_error("%s", ss.str().c_str());
+}
+
 #else
 
 void LibertyParser::error()
@@ -263,25 +375,34 @@ void LibertyParser::error()
 	exit(1);
 }
 
+void LibertyParser::error(const std::string &str)
+{
+	std::stringstream ss;
+	ss << "Syntax error in liberty file on line " << line << ".\n";
+	ss << "  " << str << "\n";
+	printf("%s", ss.str().c_str());
+	exit(1);
+}
+
 /**** BEGIN: http://svn.clifford.at/tools/trunk/examples/check.h ****/
 
 #define CHECK_NV(result, check)                                      \
    do {                                                              \
-     auto _R = (result);                                             \
-     if (!(_R check)) {                                              \
-       fprintf(stderr, "Error from '%s' (%ld %s) in %s:%d.\n",       \
-               #result, (long int)_R, #check, __FILE__, __LINE__);   \
-       abort();                                                      \
-     }                                                               \
+	 auto _R = (result);                                             \
+	 if (!(_R check)) {                                              \
+	   fprintf(stderr, "Error from '%s' (%ld %s) in %s:%d.\n",       \
+			   #result, (long int)_R, #check, __FILE__, __LINE__);   \
+	   abort();                                                      \
+	 }                                                               \
    } while(0)
 
 #define CHECK_COND(result)                                           \
    do {                                                              \
-     if (!(result)) {                                                \
-       fprintf(stderr, "Error from '%s' in %s:%d.\n",                \
-               #result, __FILE__, __LINE__);                         \
-       abort();                                                      \
-     }                                                               \
+	 if (!(result)) {                                                \
+	   fprintf(stderr, "Error from '%s' in %s:%d.\n",                \
+			   #result, __FILE__, __LINE__);                         \
+	   abort();                                                      \
+	 }                                                               \
    } while(0)
 
 /**** END: http://svn.clifford.at/tools/trunk/examples/check.h ****/
diff --git a/passes/techmap/libparse.h b/passes/techmap/libparse.h
index cf6325570..c9ebd06c5 100644
--- a/passes/techmap/libparse.h
+++ b/passes/techmap/libparse.h
@@ -46,9 +46,17 @@ namespace Yosys
 		LibertyAst *ast;
 		LibertyParser(std::istream &f) : f(f), line(1), ast(parse()) {}
 		~LibertyParser() { if (ast) delete ast; }
+        
+        /* lexer return values:
+           'v': identifier, string, array range [...] -> str holds the token string
+           'n': newline
+           anything else is a single character.
+        */
 		int lexer(std::string &str);
-		LibertyAst *parse();
+		
+        LibertyAst *parse();
 		void error();
+        void error(const std::string &str);
 	};
 }
 
diff --git a/techlibs/achronix/speedster22i/cells_sim.v b/techlibs/achronix/speedster22i/cells_sim.v
index a94dce9b1..a0c60b4be 100755
--- a/techlibs/achronix/speedster22i/cells_sim.v
+++ b/techlibs/achronix/speedster22i/cells_sim.v
@@ -30,7 +30,7 @@ endmodule
 module PADOUT (output padout, input padin, input oe);
    assign padout  = padin;
    assign oe = oe;
-endmodule 
+endmodule
 
 module LUT4 (output dout,
              input  din0, din1, din2, din3);
@@ -66,14 +66,14 @@ always @(dataa_w or datab_w or datac_w or datad_w) begin
                          datac_w, datad_w);
 end
 assign dout = combout_rt & 1'b1;
-endmodule 
+endmodule
 
 module DFF (output q,
             input  d, ck);
    reg             q;
    always @(posedge ck)
      q <= d;
-   
+
 endmodule
 
 
diff --git a/techlibs/anlogic/anlogic_eqn.cc b/techlibs/anlogic/anlogic_eqn.cc
index c025c65c4..741bf04cc 100644
--- a/techlibs/anlogic/anlogic_eqn.cc
+++ b/techlibs/anlogic/anlogic_eqn.cc
@@ -52,13 +52,13 @@ struct AnlogicEqnPass : public Pass {
 						eqn += names[j];
 					else
 						eqn += std::string("~") + names[j];
-					
+
 					if (j!=(inputs-1)) eqn += "*";
 				}
 				eqn += ")+";
 			}
 		}
-		if (eqn.empty()) return Const("0");		
+		if (eqn.empty()) return Const("0");
 		eqn = eqn.substr(0, eqn.length()-1);
 		return Const(eqn);
 	}
diff --git a/techlibs/ecp5/Makefile.inc b/techlibs/ecp5/Makefile.inc
index 8df02be5f..4db087e87 100644
--- a/techlibs/ecp5/Makefile.inc
+++ b/techlibs/ecp5/Makefile.inc
@@ -1,5 +1,5 @@
 
-OBJS += techlibs/ecp5/synth_ecp5.o
+OBJS += techlibs/ecp5/synth_ecp5.o techlibs/ecp5/ecp5_ffinit.o
 
 $(eval $(call add_share_file,share/ecp5,techlibs/ecp5/cells_map.v))
 $(eval $(call add_share_file,share/ecp5,techlibs/ecp5/cells_sim.v))
diff --git a/techlibs/ecp5/arith_map.v b/techlibs/ecp5/arith_map.v
index 1094c5f8a..eb7947601 100644
--- a/techlibs/ecp5/arith_map.v
+++ b/techlibs/ecp5/arith_map.v
@@ -33,7 +33,7 @@ module _80_ecp5_alu (A, B, CI, BI, X, Y, CO);
 	input CI, BI;
 	output [Y_WIDTH-1:0] CO;
 
-	wire _TECHMAP_FAIL_ = Y_WIDTH <= 2;
+	wire _TECHMAP_FAIL_ = Y_WIDTH <= 4;
 
 	wire [Y_WIDTH-1:0] A_buf, B_buf;
 	\$pos #(.A_SIGNED(A_SIGNED), .A_WIDTH(A_WIDTH), .Y_WIDTH(Y_WIDTH)) A_conv (.A(A), .Y(A_buf));
diff --git a/techlibs/ecp5/cells_bb.v b/techlibs/ecp5/cells_bb.v
index 425d62d24..223e19b9e 100644
--- a/techlibs/ecp5/cells_bb.v
+++ b/techlibs/ecp5/cells_bb.v
@@ -156,6 +156,41 @@ module OSCG(
 parameter DIV = 128;
 endmodule
 
+(* blackbox *) (* keep *)
+module USRMCLK(
+	input USRMCLKI, USRMCLKTS,
+	output USRMCLKO
+);
+endmodule
+
+(* blackbox *) (* keep *)
+module JTAGG(
+	input TCK, TMS, TDI, JTDO2, JTDO1,
+	output TDO, JTDI, JTCK, JRTI2, JRTI1,
+	output JSHIFT, JUPDATE, JRSTN, JCE2, JCE1
+);
+parameter ER1 = "ENABLED";
+parameter ER2 = "ENABLED";
+endmodule
+
+(* blackbox *)
+module DELAYF(
+	input A, LOADN, MOVE, DIRECTION,
+	output Z, CFLAG
+);
+	parameter DEL_MODE = "USER_DEFINED";
+	parameter DEL_VALUE = 0;
+endmodule
+
+(* blackbox *)
+module DELAYG(
+	input A,
+	output Z
+);
+	parameter DEL_MODE = "USER_DEFINED";
+	parameter DEL_VALUE = 0;
+endmodule
+
 (* blackbox *)
 module IDDRX1F(
 	input D, SCLK, RST,
@@ -165,6 +200,31 @@ module IDDRX1F(
 endmodule
 
 (* blackbox *)
+module IDDRX2F(
+	input D, SCLK, ECLK, RST,
+	output Q0, Q1, Q2, Q3
+);
+	parameter GSR = "ENABLED";
+endmodule
+
+(* blackbox *)
+module IDDR71B(
+	input D, SCLK, ECLK, RST, ALIGNWD,
+	output Q0, Q1, Q2, Q3, Q4, Q5, Q6
+);
+	parameter GSR = "ENABLED";
+endmodule
+
+(* blackbox *)
+module IDDRX2DQA(
+	input D, DQSR90, ECLK, SCLK, RST,
+	input RDPNTR2, RDPNTR1, RDPNTR0, WRPNTR2, WRPNTR1, WRPNTR0,
+	output Q0, Q1, Q2, Q3, QWL
+);
+	parameter GSR = "ENABLED";
+endmodule
+
+(* blackbox *)
 module ODDRX1F(
 	input SCLK, RST, D0, D1,
 	output Q
@@ -173,6 +233,91 @@ module ODDRX1F(
 endmodule
 
 (* blackbox *)
+module ODDRX2F(
+	input SCLK, ECLK, RST, D0, D1, D2, D3,
+	output Q
+);
+	parameter GSR = "ENABLED";
+endmodule
+
+(* blackbox *)
+module ODDR71B(
+	input SCLK, ECLK, RST, D0, D1, D2, D3, D4, D5, D6,
+	output Q
+);
+	parameter GSR = "ENABLED";
+endmodule
+
+(* blackbox *)
+module OSHX2A(
+	input D0, D1, RST, ECLK, SCLK,
+	output Q
+);
+	parameter GSR = "ENABLED";
+endmodule
+
+(* blackbox *)
+module ODDRX2DQA(
+	input D0, D1, D2, D3, RST, ECLK, SCLK, DQSW270,
+	output Q
+);
+	parameter GSR = "ENABLED";
+endmodule
+
+(* blackbox *)
+module ODDRX2DQSB(
+	input D0, D1, D2, D3, RST, ECLK, SCLK, DQSW,
+	output Q
+);
+	parameter GSR = "ENABLED";
+endmodule
+
+(* blackbox *)
+module TSHX2DQA(
+	input T0, T1, SCLK, ECLK, DQSW270, RST,
+	output Q
+);
+	parameter GSR = "ENABLED";
+	parameter REGSET = "SET";
+endmodule
+
+(* blackbox *)
+module TSHX2DQSA(
+	input T0, T1, SCLK, ECLK, DQSW, RST,
+	output Q
+);
+	parameter GSR = "ENABLED";
+	parameter REGSET = "SET";
+endmodule
+
+(* blackbox *)
+module DQSBUFM(
+	input DQSI, READ1, READ0, READCLKSEL2, READCLKSEL1, READCLKSEL0, DDRDEL,
+	input ECLK, SCLK,
+	input DYNDELAY7, DYNDELAY6, DYNDELAY5, DYNDELAY4,
+	input DYNDELAY3, DYNDELAY2, DYNDELAY1, DYNDELAY0, 
+	input RST, RDLOADN, RDMOVE, RDDIRECTION, WRLOADN, WRMOVE, WRDIRECTION, PAUSE,
+	output DQSR90, DQSW, DQSW270,
+	output RDPNTR2, RDPNTR1, RDPNTR0, WRPNTR2, WRPNTR1, WRPNTR0,
+	output DATAVALID, BURSTDET, RDCFLAG, WRCFLAG
+);
+	parameter DQS_LI_DEL_ADJ = "FACTORYONLY";
+	parameter DQS_LI_DEL_VAL = 0;
+	parameter DQS_LO_DEL_ADJ = "FACTORYONLY";
+	parameter DQS_LO_DEL_VAL = 0;
+	parameter GSR = "ENABLED";
+endmodule
+
+(* blackbox *)
+module DDRDLLA(
+	input CLK, RST, UDDCNTLN, FREEZE,
+	output LOCK, DDRDEL, DCNTL7, DCNTL6, DCNTL5, DCNTL4, DCNTL3, DCNTL2, DCNTL1, DCNTL0
+);
+	parameter FORCE_MAX_DELAY = "NO";
+	parameter GSR = "ENABLED";
+endmodule
+
+(* blackbox *)
 module CLKDIVF(
 	input CLKI, RST, ALIGNWD,
 	output CDIVX
@@ -182,6 +327,13 @@ module CLKDIVF(
 endmodule
 
 (* blackbox *)
+module ECLKSYNCB(
+	input ECLKI, STOP,
+	output ECLKO
+);
+endmodule
+
+(* blackbox *)
 module DCCA(
 	input CLKI, CE,
 	output CLKO
diff --git a/techlibs/ecp5/cells_map.v b/techlibs/ecp5/cells_map.v
index 23182bdeb..6ab4b69f2 100644
--- a/techlibs/ecp5/cells_map.v
+++ b/techlibs/ecp5/cells_map.v
@@ -47,6 +47,9 @@ 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
 
+// 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
+
 `ifndef NO_LUT
 module \$lut (A, Y);
     parameter WIDTH = 0;
diff --git a/techlibs/ecp5/cells_sim.v b/techlibs/ecp5/cells_sim.v
index f27540bd7..1e4002ee0 100644
--- a/techlibs/ecp5/cells_sim.v
+++ b/techlibs/ecp5/cells_sim.v
@@ -203,13 +203,14 @@ endmodule
 
 // ---------------------------------------
 
-module TRELLIS_FF(input CLK, LSR, CE, DI, output reg Q);
+module TRELLIS_FF(input CLK, LSR, CE, DI, M, output reg Q);
 	parameter GSR = "ENABLED";
 	parameter [127:0] CEMUX = "1";
 	parameter CLKMUX = "CLK";
 	parameter LSRMUX = "LSR";
 	parameter SRMODE = "LSR_OVER_CE";
 	parameter REGSET = "RESET";
+	parameter [127:0] LSRMODE = "LSR";
 
 	reg muxce;
 	always @(*)
@@ -222,8 +223,13 @@ module TRELLIS_FF(input CLK, LSR, CE, DI, output reg Q);
 
 	wire muxlsr = (LSRMUX == "INV") ? ~LSR : LSR;
 	wire muxclk = (CLKMUX == "INV") ? ~CLK : CLK;
-
-	localparam srval = (REGSET == "SET") ? 1'b1 : 1'b0;
+	wire srval;
+	generate
+		if (LSRMODE == "PRLD")
+			assign srval = M;
+		else
+			assign srval = (REGSET == "SET") ? 1'b1 : 1'b0;
+	endgenerate
 
 	initial Q = srval;
 
@@ -339,6 +345,8 @@ module TRELLIS_SLICE(
 	parameter REG1_SD = "0";
 	parameter REG0_REGSET = "RESET";
 	parameter REG1_REGSET = "RESET";
+	parameter REG0_LSRMODE = "LSR";
+	parameter REG1_LSRMODE = "LSR";
 	parameter [127:0] CCU2_INJECT1_0 = "NO";
 	parameter [127:0] CCU2_INJECT1_1 = "NO";
 	parameter WREMUX = "WRE";
@@ -428,10 +436,11 @@ module TRELLIS_SLICE(
 		.CLKMUX(CLKMUX),
 		.LSRMUX(LSRMUX),
 		.SRMODE(SRMODE),
-		.REGSET(REG0_REGSET)
+		.REGSET(REG0_REGSET),
+		.LSRMODE(REG0_LSRMODE)
 	) ff_0 (
 		.CLK(CLK), .LSR(LSR), .CE(CE),
-		.DI(muxdi0),
+		.DI(muxdi0), .M(M0),
 		.Q(Q0)
 	);
 	TRELLIS_FF #(
@@ -440,10 +449,11 @@ module TRELLIS_SLICE(
 		.CLKMUX(CLKMUX),
 		.LSRMUX(LSRMUX),
 		.SRMODE(SRMODE),
-		.REGSET(REG1_REGSET)
+		.REGSET(REG1_REGSET),
+		.LSRMODE(REG1_LSRMODE)
 	) ff_1 (
 		.CLK(CLK), .LSR(LSR), .CE(CE),
-		.DI(muxdi1),
+		.DI(muxdi1), .M(M1),
 		.Q(Q1)
 	);
 endmodule
@@ -547,3 +557,20 @@ module DP16KD(
   parameter INITVAL_3E = 320'h00000000000000000000000000000000000000000000000000000000000000000000000000000000;
   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
diff --git a/techlibs/ecp5/ecp5_ffinit.cc b/techlibs/ecp5/ecp5_ffinit.cc
new file mode 100644
index 000000000..dbd16cac9
--- /dev/null
+++ b/techlibs/ecp5/ecp5_ffinit.cc
@@ -0,0 +1,203 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *  Copyright (C) 2018-19  David Shah <david@symbioticeda.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 Ecp5FfinitPass : public Pass {
+	Ecp5FfinitPass() : Pass("ecp5_ffinit", "ECP5: handle FF init values") { }
+	void help() YS_OVERRIDE
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    ecp5_ffinit [options] [selection]\n");
+		log("\n");
+		log("Remove init values for FF output signals when equal to reset value.\n");
+		log("If reset is not used, set the reset value to the init value, otherwise\n");
+		log("unmap out the reset (if not an async reset).\n");
+	}
+	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
+	{
+		log_header(design, "Executing ECP5_FFINIT pass (implement FF init values).\n");
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++)
+		{
+			// if (args[argidx] == "-singleton") {
+			// 	singleton_mode = true;
+			// 	continue;
+			// }
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		for (auto module : design->selected_modules())
+		{
+			log("Handling FF init values in %s.\n", log_id(module));
+
+			SigMap sigmap(module);
+			pool<Wire*> init_wires;
+			dict<SigBit, State> initbits;
+			dict<SigBit, SigBit> initbit_to_wire;
+			pool<SigBit> handled_initbits;
+
+			for (auto wire : module->selected_wires())
+			{
+				if (wire->attributes.count("\\init") == 0)
+					continue;
+
+				SigSpec wirebits = sigmap(wire);
+				Const initval = wire->attributes.at("\\init");
+				init_wires.insert(wire);
+
+				for (int i = 0; i < GetSize(wirebits) && i < GetSize(initval); i++)
+				{
+					SigBit bit = wirebits[i];
+					State val = initval[i];
+
+					if (val != State::S0 && val != State::S1)
+						continue;
+
+					if (initbits.count(bit)) {
+						if (initbits.at(bit) != val) {
+							log_warning("Conflicting init values for signal %s (%s = %s, %s = %s).\n",
+									log_signal(bit), log_signal(SigBit(wire, i)), log_signal(val),
+									log_signal(initbit_to_wire[bit]), log_signal(initbits.at(bit)));
+							initbits.at(bit) = State::Sx;
+						}
+						continue;
+					}
+
+					initbits[bit] = val;
+					initbit_to_wire[bit] = SigBit(wire, i);
+				}
+			}
+			for (auto cell : module->selected_cells())
+			{
+				if (cell->type != "\\TRELLIS_FF")
+					continue;
+				SigSpec sig_d = cell->getPort("\\DI");
+				SigSpec sig_q = cell->getPort("\\Q");
+				SigSpec sig_lsr = cell->getPort("\\LSR");
+
+				if (GetSize(sig_d) < 1 || GetSize(sig_q) < 1)
+					continue;
+
+				SigBit bit_d = sigmap(sig_d[0]);
+				SigBit bit_q = sigmap(sig_q[0]);
+
+				std::string regset = "RESET";
+				if (cell->hasParam("\\REGSET"))
+					regset = cell->getParam("\\REGSET").decode_string();
+				State resetState;
+				if (regset == "SET")
+					resetState = State::S1;
+				else if (regset == "RESET")
+					resetState = State::S0;
+				else
+					log_error("FF cell %s has illegal REGSET value %s.\n",
+						log_id(cell), regset.c_str());
+
+				if (!initbits.count(bit_q))
+					continue;
+
+				State val = initbits.at(bit_q);
+
+				if (val == State::Sx)
+					continue;
+
+				log("FF init value for cell %s (%s): %s = %c\n", log_id(cell), log_id(cell->type),
+						log_signal(bit_q), val != State::S0 ? '1' : '0');
+				// Initval is the same as the reset state. Matches hardware, nowt more to do
+				if (val == resetState) {
+					handled_initbits.insert(bit_q);
+					continue;
+				}
+
+				if (GetSize(sig_lsr) >= 1 && sig_lsr[0] != State::S0) {
+					std::string srmode = "LSR_OVER_CE";
+					if (cell->hasParam("\\SRMODE"))
+						srmode = cell->getParam("\\SRMODE").decode_string();
+					if (srmode == "ASYNC") {
+						log("Async reset value %c for FF cell %s inconsistent with init value %c.\n",
+							resetState != State::S0 ? '1' : '0', log_id(cell), val != State::S0 ? '1' : '0');
+					} else {
+						SigBit bit_lsr = sigmap(sig_lsr[0]);
+						Wire *new_bit_d = module->addWire(NEW_ID);
+						if (resetState == State::S0) {
+							module->addAndnotGate(NEW_ID, bit_d, bit_lsr, new_bit_d);
+						} else {
+							module->addOrGate(NEW_ID, bit_d, bit_lsr, new_bit_d);
+						}
+
+						cell->setPort("\\DI", new_bit_d);
+						cell->setPort("\\LSR", State::S0);
+
+						if(cell->hasPort("\\CE")) {
+							std::string cemux = "CE";
+							if (cell->hasParam("\\CEMUX"))
+								cemux = cell->getParam("\\CEMUX").decode_string();
+							SigSpec sig_ce = cell->getPort("\\CE");
+							if (GetSize(sig_ce) >= 1) {
+								SigBit bit_ce = sigmap(sig_ce[0]);
+								Wire *new_bit_ce = module->addWire(NEW_ID);
+								if (cemux == "INV")
+									module->addAndnotGate(NEW_ID, bit_ce, bit_lsr, new_bit_ce);
+								else
+									module->addOrGate(NEW_ID, bit_ce, bit_lsr, new_bit_ce);
+								cell->setPort("\\CE", new_bit_ce);
+							}
+						}
+						cell->setParam("\\REGSET", val != State::S0 ? Const("SET") : Const("RESET"));
+						handled_initbits.insert(bit_q);
+					}
+				} else {
+					cell->setParam("\\REGSET", val != State::S0 ? Const("SET") : Const("RESET"));
+					handled_initbits.insert(bit_q);
+				}
+			}
+
+			for (auto wire : init_wires)
+			{
+				if (wire->attributes.count("\\init") == 0)
+					continue;
+
+				SigSpec wirebits = sigmap(wire);
+				Const &initval = wire->attributes.at("\\init");
+				bool remove_attribute = true;
+
+				for (int i = 0; i < GetSize(wirebits) && i < GetSize(initval); i++) {
+					if (handled_initbits.count(wirebits[i]))
+						initval[i] = State::Sx;
+					else if (initval[i] != State::Sx)
+						remove_attribute = false;
+				}
+
+				if (remove_attribute)
+					wire->attributes.erase("\\init");
+			}
+		}
+	}
+} Ecp5FfinitPass;
+
+PRIVATE_NAMESPACE_END
diff --git a/techlibs/ecp5/synth_ecp5.cc b/techlibs/ecp5/synth_ecp5.cc
index bda03d251..4b889d672 100644
--- a/techlibs/ecp5/synth_ecp5.cc
+++ b/techlibs/ecp5/synth_ecp5.cc
@@ -255,10 +255,7 @@ struct SynthEcp5Pass : public ScriptPass
 			run("techmap -D NO_LUT -map +/ecp5/cells_map.v");
 			run("opt_expr -mux_undef");
 			run("simplemap");
-			// TODO
-#if 0
 			run("ecp5_ffinit");
-#endif
 		}
 
 		if (check_label("map_luts"))
diff --git a/techlibs/gowin/arith_map.v b/techlibs/gowin/arith_map.v
index 25e789e4a..e15de6423 100644
--- a/techlibs/gowin/arith_map.v
+++ b/techlibs/gowin/arith_map.v
@@ -25,24 +25,24 @@ module _80_gw1n_alu(A, B, CI, BI, X, Y, CO);
    parameter A_WIDTH = 1;
    parameter B_WIDTH = 1;
    parameter Y_WIDTH = 1;
-   
+
    input [A_WIDTH-1:0] A;
    input [B_WIDTH-1:0] B;
    output [Y_WIDTH-1:0] X, Y;
-   
+
    input 		CI, BI;
    output [Y_WIDTH-1:0] CO;
-   
+
    wire 		_TECHMAP_FAIL_ = Y_WIDTH <= 2;
-   
+
    wire [Y_WIDTH-1:0] 	A_buf, B_buf;
    \$pos #(.A_SIGNED(A_SIGNED), .A_WIDTH(A_WIDTH), .Y_WIDTH(Y_WIDTH)) A_conv (.A(A), .Y(A_buf));
    \$pos #(.A_SIGNED(B_SIGNED), .A_WIDTH(B_WIDTH), .Y_WIDTH(Y_WIDTH)) B_conv (.A(B), .Y(B_buf));
-   
+
    wire [Y_WIDTH-1:0] 	AA = A_buf;
    wire [Y_WIDTH-1:0] 	BB = BI ? ~B_buf : B_buf;
    wire [Y_WIDTH-1:0] 	C = {CO, CI};
-   
+
    genvar 		i;
    generate for (i = 0; i < Y_WIDTH; i = i + 1) begin:slice
       ALU #(.ALU_MODE(32'b0))
diff --git a/techlibs/gowin/synth_gowin.cc b/techlibs/gowin/synth_gowin.cc
index 96128a680..9a3fcdbb6 100644
--- a/techlibs/gowin/synth_gowin.cc
+++ b/techlibs/gowin/synth_gowin.cc
@@ -111,7 +111,7 @@ struct SynthGowinPass : public ScriptPass
 			if (args[argidx] == "-noflatten") {
 				flatten = false;
 				continue;
-			}			
+			}
 			break;
 		}
 		extra_args(args, argidx, design);
diff --git a/techlibs/ice40/Makefile.inc b/techlibs/ice40/Makefile.inc
index 2750901c8..723b59d6f 100644
--- a/techlibs/ice40/Makefile.inc
+++ b/techlibs/ice40/Makefile.inc
@@ -1,5 +1,6 @@
 
 OBJS += techlibs/ice40/synth_ice40.o
+OBJS += techlibs/ice40/ice40_braminit.o
 OBJS += techlibs/ice40/ice40_ffssr.o
 OBJS += techlibs/ice40/ice40_ffinit.o
 OBJS += techlibs/ice40/ice40_opt.o
diff --git a/techlibs/ice40/brams_map.v b/techlibs/ice40/brams_map.v
index 19a61d73b..ad3bccd21 100644
--- a/techlibs/ice40/brams_map.v
+++ b/techlibs/ice40/brams_map.v
@@ -7,8 +7,8 @@ module \$__ICE40_RAM4K (
 	input  [10:0] WADDR,
 	input  [15:0] MASK, WDATA
 );
-	parameter integer READ_MODE = 0;
-	parameter integer WRITE_MODE = 0;
+	parameter [1:0] READ_MODE = 0;
+	parameter [1:0] WRITE_MODE = 0;
 	parameter [0:0] NEGCLK_R = 0;
 	parameter [0:0] NEGCLK_W = 0;
 
diff --git a/techlibs/ice40/cells_sim.v b/techlibs/ice40/cells_sim.v
index 2041693cc..62a28364b 100644
--- a/techlibs/ice40/cells_sim.v
+++ b/techlibs/ice40/cells_sim.v
@@ -326,6 +326,8 @@ module SB_RAM40_4K (
 	parameter INIT_E = 256'h0000000000000000000000000000000000000000000000000000000000000000;
 	parameter INIT_F = 256'h0000000000000000000000000000000000000000000000000000000000000000;
 
+	parameter INIT_FILE = "";
+
 `ifndef BLACKBOX
 	wire [15:0] WMASK_I;
 	wire [15:0] RMASK_I;
@@ -408,43 +410,27 @@ module SB_RAM40_4K (
 	reg [15:0] memory [0:255];
 
 	initial begin
-		for (i=0; i<16; i=i+1) begin
-`ifdef YOSYS
-			memory[ 0*16 + i] <= INIT_0[16*i +: 16];
-			memory[ 1*16 + i] <= INIT_1[16*i +: 16];
-			memory[ 2*16 + i] <= INIT_2[16*i +: 16];
-			memory[ 3*16 + i] <= INIT_3[16*i +: 16];
-			memory[ 4*16 + i] <= INIT_4[16*i +: 16];
-			memory[ 5*16 + i] <= INIT_5[16*i +: 16];
-			memory[ 6*16 + i] <= INIT_6[16*i +: 16];
-			memory[ 7*16 + i] <= INIT_7[16*i +: 16];
-			memory[ 8*16 + i] <= INIT_8[16*i +: 16];
-			memory[ 9*16 + i] <= INIT_9[16*i +: 16];
-			memory[10*16 + i] <= INIT_A[16*i +: 16];
-			memory[11*16 + i] <= INIT_B[16*i +: 16];
-			memory[12*16 + i] <= INIT_C[16*i +: 16];
-			memory[13*16 + i] <= INIT_D[16*i +: 16];
-			memory[14*16 + i] <= INIT_E[16*i +: 16];
-			memory[15*16 + i] <= INIT_F[16*i +: 16];
-`else
-			memory[ 0*16 + i] = INIT_0[16*i +: 16];
-			memory[ 1*16 + i] = INIT_1[16*i +: 16];
-			memory[ 2*16 + i] = INIT_2[16*i +: 16];
-			memory[ 3*16 + i] = INIT_3[16*i +: 16];
-			memory[ 4*16 + i] = INIT_4[16*i +: 16];
-			memory[ 5*16 + i] = INIT_5[16*i +: 16];
-			memory[ 6*16 + i] = INIT_6[16*i +: 16];
-			memory[ 7*16 + i] = INIT_7[16*i +: 16];
-			memory[ 8*16 + i] = INIT_8[16*i +: 16];
-			memory[ 9*16 + i] = INIT_9[16*i +: 16];
-			memory[10*16 + i] = INIT_A[16*i +: 16];
-			memory[11*16 + i] = INIT_B[16*i +: 16];
-			memory[12*16 + i] = INIT_C[16*i +: 16];
-			memory[13*16 + i] = INIT_D[16*i +: 16];
-			memory[14*16 + i] = INIT_E[16*i +: 16];
-			memory[15*16 + i] = INIT_F[16*i +: 16];
-`endif
-		end
+		if (INIT_FILE != "")
+			$readmemh(INIT_FILE, memory);
+		else
+			for (i=0; i<16; i=i+1) begin
+				memory[ 0*16 + i] = INIT_0[16*i +: 16];
+				memory[ 1*16 + i] = INIT_1[16*i +: 16];
+				memory[ 2*16 + i] = INIT_2[16*i +: 16];
+				memory[ 3*16 + i] = INIT_3[16*i +: 16];
+				memory[ 4*16 + i] = INIT_4[16*i +: 16];
+				memory[ 5*16 + i] = INIT_5[16*i +: 16];
+				memory[ 6*16 + i] = INIT_6[16*i +: 16];
+				memory[ 7*16 + i] = INIT_7[16*i +: 16];
+				memory[ 8*16 + i] = INIT_8[16*i +: 16];
+				memory[ 9*16 + i] = INIT_9[16*i +: 16];
+				memory[10*16 + i] = INIT_A[16*i +: 16];
+				memory[11*16 + i] = INIT_B[16*i +: 16];
+				memory[12*16 + i] = INIT_C[16*i +: 16];
+				memory[13*16 + i] = INIT_D[16*i +: 16];
+				memory[14*16 + i] = INIT_E[16*i +: 16];
+				memory[15*16 + i] = INIT_F[16*i +: 16];
+			end
 	end
 
 	always @(posedge WCLK) begin
@@ -504,6 +490,8 @@ module SB_RAM40_4KNR (
 	parameter INIT_E = 256'h0000000000000000000000000000000000000000000000000000000000000000;
 	parameter INIT_F = 256'h0000000000000000000000000000000000000000000000000000000000000000;
 
+	parameter INIT_FILE = "";
+
 	SB_RAM40_4K #(
 		.WRITE_MODE(WRITE_MODE),
 		.READ_MODE (READ_MODE ),
@@ -522,7 +510,8 @@ module SB_RAM40_4KNR (
 		.INIT_C    (INIT_C    ),
 		.INIT_D    (INIT_D    ),
 		.INIT_E    (INIT_E    ),
-		.INIT_F    (INIT_F    )
+		.INIT_F    (INIT_F    ),
+		.INIT_FILE (INIT_FILE )
 	) RAM (
 		.RDATA(RDATA),
 		.RCLK (~RCLKN),
@@ -566,6 +555,8 @@ module SB_RAM40_4KNW (
 	parameter INIT_E = 256'h0000000000000000000000000000000000000000000000000000000000000000;
 	parameter INIT_F = 256'h0000000000000000000000000000000000000000000000000000000000000000;
 
+	parameter INIT_FILE = "";
+
 	SB_RAM40_4K #(
 		.WRITE_MODE(WRITE_MODE),
 		.READ_MODE (READ_MODE ),
@@ -584,7 +575,8 @@ module SB_RAM40_4KNW (
 		.INIT_C    (INIT_C    ),
 		.INIT_D    (INIT_D    ),
 		.INIT_E    (INIT_E    ),
-		.INIT_F    (INIT_F    )
+		.INIT_F    (INIT_F    ),
+		.INIT_FILE (INIT_FILE )
 	) RAM (
 		.RDATA(RDATA),
 		.RCLK (RCLK ),
@@ -628,6 +620,8 @@ module SB_RAM40_4KNRNW (
 	parameter INIT_E = 256'h0000000000000000000000000000000000000000000000000000000000000000;
 	parameter INIT_F = 256'h0000000000000000000000000000000000000000000000000000000000000000;
 
+	parameter INIT_FILE = "";
+
 	SB_RAM40_4K #(
 		.WRITE_MODE(WRITE_MODE),
 		.READ_MODE (READ_MODE ),
@@ -646,7 +640,8 @@ module SB_RAM40_4KNRNW (
 		.INIT_C    (INIT_C    ),
 		.INIT_D    (INIT_D    ),
 		.INIT_E    (INIT_E    ),
-		.INIT_F    (INIT_F    )
+		.INIT_F    (INIT_F    ),
+		.INIT_FILE (INIT_FILE )
 	) RAM (
 		.RDATA(RDATA),
 		.RCLK (~RCLKN),
diff --git a/techlibs/ice40/ice40_braminit.cc b/techlibs/ice40/ice40_braminit.cc
new file mode 100644
index 000000000..4fa6b0792
--- /dev/null
+++ b/techlibs/ice40/ice40_braminit.cc
@@ -0,0 +1,159 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *
+ *  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"
+#include <stdlib.h>
+#include <stdio.h>
+#include <bitset>
+
+USING_YOSYS_NAMESPACE
+PRIVATE_NAMESPACE_BEGIN
+
+static void run_ice40_braminit(Module *module)
+{
+	for (auto cell : module->selected_cells())
+	{
+		uint16_t mem[256];
+
+		/* Only consider cells we're interested in */
+		if (cell->type != "\\SB_RAM40_4K" &&
+		    cell->type != "\\SB_RAM40_4KNR" &&
+		    cell->type != "\\SB_RAM40_4KNW" &&
+		    cell->type != "\\SB_RAM40_4KNRNW")
+			continue;
+		if (!cell->hasParam("\\INIT_FILE"))
+			continue;
+		std::string init_file = cell->getParam("\\INIT_FILE").decode_string();
+		cell->unsetParam("\\INIT_FILE");
+		if (init_file == "")
+			continue;
+
+		/* Open file */
+		log("Processing %s : %s\n", RTLIL::id2cstr(cell->name), init_file.c_str());
+
+		std::ifstream f;
+		f.open(init_file.c_str());
+		if (f.fail()) {
+			log("Can not open file `%s`.\n", init_file.c_str());
+			continue;
+		}
+
+		/* Defaults to 0 */
+		memset(mem, 0x00, sizeof(mem));
+
+		/* Process each line */
+		bool in_comment = false;
+		int cursor = 0;
+
+		while (!f.eof())
+		{
+			std::string line, token;
+			std::getline(f, line);
+
+			for (int i = 0; i < GetSize(line); i++)
+			{
+				if (in_comment && line.substr(i, 2) == "*/") {
+					line[i] = ' ';
+					line[i+1] = ' ';
+					in_comment = false;
+					continue;
+				}
+				if (!in_comment && line.substr(i, 2) == "/*")
+					in_comment = true;
+				if (in_comment)
+					line[i] = ' ';
+			}
+
+			while (1)
+			{
+				bool set_cursor = false;
+				long value;
+
+				token = next_token(line, " \t\r\n");
+				if (token.empty() || token.substr(0, 2) == "//")
+					break;
+
+				if (token[0] == '@') {
+					token = token.substr(1);
+					set_cursor = true;
+				}
+
+				const char *nptr = token.c_str();
+				char *endptr;
+				value = strtol(nptr, &endptr, 16);
+				if (!*nptr || *endptr) {
+					log("Can not parse %s `%s` for %s.\n",
+						set_cursor ? "address" : "value",
+						nptr, token.c_str()
+					);
+					continue;
+				}
+
+				if (set_cursor)
+					cursor = value;
+				else if (cursor >= 0 && cursor < 256)
+					mem[cursor++] = value;
+				else
+					log("Attempt to initialize non existent address %d\n", cursor);
+			}
+		}
+
+		/* Set attributes */
+		const char *hex = "0123456789ABCDEF";
+		for (int i=0; i<16; i++) {
+			std::string val = "";
+			for (int j=15; j>=0; j--)
+				val += std::bitset<16>(mem[i*16+j]).to_string();
+			cell->setParam("\\INIT_" + std::string(1, hex[i]), RTLIL::Const::from_string(val));
+		}
+	}
+}
+
+struct Ice40BRAMInitPass : public Pass {
+	Ice40BRAMInitPass() : Pass("ice40_braminit", "iCE40: perform SB_RAM40_4K initialization from file") { }
+	void help() YS_OVERRIDE
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    ice40_braminit\n");
+		log("\n");
+		log("This command processes all SB_RAM40_4K blocks with a non-empty INIT_FILE\n");
+		log("parameter and converts it into the required INIT_x attributes\n");
+		log("\n");
+	}
+	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
+	{
+		log_header(design, "Executing ICE40_BRAMINIT pass.\n");
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++) {
+			// if (args[argidx] == "-???") {
+			//  continue;
+			// }
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		for (auto module : design->selected_modules())
+			run_ice40_braminit(module);
+	}
+} Ice40BRAMInitPass;
+
+PRIVATE_NAMESPACE_END
diff --git a/techlibs/ice40/synth_ice40.cc b/techlibs/ice40/synth_ice40.cc
index 621b0b2bc..6c77e5482 100644
--- a/techlibs/ice40/synth_ice40.cc
+++ b/techlibs/ice40/synth_ice40.cc
@@ -266,6 +266,7 @@ struct SynthIce40Pass : public ScriptPass
 		{
 			run("memory_bram -rules +/ice40/brams.txt");
 			run("techmap -map +/ice40/brams_map.v");
+			run("ice40_braminit");
 		}
 
 		if (check_label("map"))
diff --git a/techlibs/intel/cycloneive/arith_map.v b/techlibs/intel/cycloneive/arith_map.v
index b3a11272b..49e36aa25 100644
--- a/techlibs/intel/cycloneive/arith_map.v
+++ b/techlibs/intel/cycloneive/arith_map.v
@@ -32,7 +32,7 @@ module fa
    wire   VCC;
 
    assign VCC = 1'b1;
-   
+
    cycloneiv_lcell_comb gen_sum_0 (.combout(sum_x),
                                    .dataa(a_c),
                                    .datab(b_c),
@@ -40,7 +40,7 @@ module fa
                                    .datad(VCC));
    defparam syn__05_.lut_mask = 16'b1001011010010110;
    defparam syn__05_.sum_lutc_input = "datac";
-   
+
    cycloneiv_lcell_comb gen_cout_0 (.combout(cout_t),
                                     .dataa(cin_c),
                                     .datab(b_c),
@@ -48,11 +48,11 @@ module fa
                                     .datad(VCC));
    defparam syn__06_.lut_mask = 16'b1110000011100000;
    defparam syn__06_.sum_lutc_input = "datac";
-   
+
 endmodule // fa
 
 module f_stage();
-   
+
 endmodule // f_stage
 
 module f_end();
@@ -88,7 +88,7 @@ module _80_cycloneive_alu (A, B, CI, BI, X, Y, CO);
           .cin_c(C[0]),
           .cout_t(C0[1]),
           .sum_x(Y[0]));
-   
+
    genvar i;
    generate for (i = 1; i < Y_WIDTH; i = i + 1) begin:slice
       cycloneive_lcell_comb #(.lut_mask(16'b0101_1010_0101_0000), .sum_lutc_input("cin")) arith_cell (.combout(Y[i]), .cout(CO[i]), .dataa(BB[i]), .datab(1'b1), .datac(1'b1), .datad(1'b1), .cin(C[i]));
diff --git a/techlibs/intel/cyclonev/cells_map.v b/techlibs/intel/cyclonev/cells_map.v
index bd60d4e17..f8d142bc9 100644
--- a/techlibs/intel/cyclonev/cells_map.v
+++ b/techlibs/intel/cyclonev/cells_map.v
@@ -76,7 +76,7 @@ module \$lut (A, Y);
    wire              VCC;
    wire              GND;
    assign {VCC,GND} = {1'b1,1'b0};
-   
+
    generate
       if (WIDTH == 1) begin
 	 assign Y = ~A[0]; // Not need to spend 1 logic cell for such an easy function
@@ -151,7 +151,7 @@ module \$lut (A, Y);
                     TODO: There's not a just 7-input function on Cyclone V, see the following note:
                     **Extended LUT Mode**
                     Use extended LUT mode to implement a specific set of 7-input functions. The set must
-                    be a 2-to-1 multiplexer fed by two arbitrary 5-input functions sharing four inputs. 
+                    be a 2-to-1 multiplexer fed by two arbitrary 5-input functions sharing four inputs.
                     [source](Device Interfaces and Integration Basics for Cyclone V Devices).
                   end*/
                   else
diff --git a/techlibs/sf2/cells_map.v b/techlibs/sf2/cells_map.v
index 5b8888294..6ad7807d2 100644
--- a/techlibs/sf2/cells_map.v
+++ b/techlibs/sf2/cells_map.v
@@ -1,40 +1,54 @@
-// module  \$_DFF_N_ (input D, C, output Q); SB_DFFN _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C)); endmodule
+module  \$_DFF_N_ (input D, C, output Q);
+  SLE _TECHMAP_REPLACE_ (.D(D), .CLK(!C), .EN(1'b1), .ALn(1'b1), .ADn(1'b1), .SLn(1'b1), .SD(1'b0), .LAT(1'b0), .Q(Q));
+endmodule
 
 module  \$_DFF_P_ (input D, C, output Q);
-  SLE _TECHMAP_REPLACE_ (
-    .D(D),
-    .CLK(C),
-    .EN(1'b1),
-    .ALn(1'b1),
-    .ADn(1'b1),
-    .SLn(1'b1),
-    .SD(1'b0),
-    .LAT(1'b0),
-    .Q(Q)
-  );
+  SLE _TECHMAP_REPLACE_ (.D(D), .CLK(C), .EN(1'b1), .ALn(1'b1), .ADn(1'b1), .SLn(1'b1), .SD(1'b0), .LAT(1'b0), .Q(Q));
+endmodule
+
+module \$_DFF_NN0_ (input D, C, R, output Q);
+  SLE _TECHMAP_REPLACE_ (.D(D), .CLK(!C), .EN(1'b1), .ALn(R), .ADn(1'b1), .SLn(1'b1), .SD(1'b0), .LAT(1'b0), .Q(Q));
+endmodule
+
+module \$_DFF_NN1_ (input D, C, R, output Q);
+  SLE _TECHMAP_REPLACE_ (.D(D), .CLK(!C), .EN(1'b1), .ALn(R), .ADn(1'b0), .SLn(1'b1), .SD(1'b0), .LAT(1'b0), .Q(Q));
+endmodule
+
+module \$_DFF_NP0_ (input D, C, R, output Q);
+  SLE _TECHMAP_REPLACE_ (.D(D), .CLK(!C), .EN(1'b1), .ALn(!R), .ADn(1'b1), .SLn(1'b1), .SD(1'b0), .LAT(1'b0), .Q(Q));
+endmodule
+
+module \$_DFF_NP1_ (input D, C, R, output Q);
+  SLE _TECHMAP_REPLACE_ (.D(D), .CLK(!C), .EN(1'b1), .ALn(!R), .ADn(1'b0), .SLn(1'b1), .SD(1'b0), .LAT(1'b0), .Q(Q));
+endmodule
+
+module \$_DFF_PN0_ (input D, C, R, output Q);
+  SLE _TECHMAP_REPLACE_ (.D(D), .CLK(C), .EN(1'b1), .ALn(R), .ADn(1'b1), .SLn(1'b1), .SD(1'b0), .LAT(1'b0), .Q(Q));
+endmodule
+
+module \$_DFF_PN1_ (input D, C, R, output Q);
+  SLE _TECHMAP_REPLACE_ (.D(D), .CLK(C), .EN(1'b1), .ALn(R), .ADn(1'b0), .SLn(1'b1), .SD(1'b0), .LAT(1'b0), .Q(Q));
+endmodule
+
+module \$_DFF_PP0_ (input D, C, R, output Q);
+  SLE _TECHMAP_REPLACE_ (.D(D), .CLK(C), .EN(1'b1), .ALn(!R), .ADn(1'b1), .SLn(1'b1), .SD(1'b0), .LAT(1'b0), .Q(Q));
+endmodule
+
+module \$_DFF_PP1_ (input D, C, R, output Q);
+  SLE _TECHMAP_REPLACE_ (.D(D), .CLK(C), .EN(1'b1), .ALn(!R), .ADn(1'b0), .SLn(1'b1), .SD(1'b0), .LAT(1'b0), .Q(Q));
 endmodule
 
 // module  \$_DFFE_NN_ (input D, C, E, output Q); SB_DFFNE _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .E(!E)); endmodule
 // module  \$_DFFE_PN_ (input D, C, E, output Q); SB_DFFE  _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .E(!E)); endmodule
-// 
+//
 // module  \$_DFFE_NP_ (input D, C, E, output Q); SB_DFFNE _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .E(E)); endmodule
 // module  \$_DFFE_PP_ (input D, C, E, output Q); SB_DFFE  _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .E(E)); endmodule
-// 
-// module  \$_DFF_NN0_ (input D, C, R, output Q); SB_DFFNR _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .R(!R)); endmodule
-// module  \$_DFF_NN1_ (input D, C, R, output Q); SB_DFFNS _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .S(!R)); endmodule
-// module  \$_DFF_PN0_ (input D, C, R, output Q); SB_DFFR  _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .R(!R)); endmodule
-// module  \$_DFF_PN1_ (input D, C, R, output Q); SB_DFFS  _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .S(!R)); endmodule
-// 
-// module  \$_DFF_NP0_ (input D, C, R, output Q); SB_DFFNR _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .R(R)); endmodule
-// module  \$_DFF_NP1_ (input D, C, R, output Q); SB_DFFNS _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .S(R)); endmodule
-// module  \$_DFF_PP0_ (input D, C, R, output Q); SB_DFFR  _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .R(R)); endmodule
-// module  \$_DFF_PP1_ (input D, C, R, output Q); SB_DFFS  _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .S(R)); endmodule
-// 
+//
 // module  \$__DFFE_NN0 (input D, C, E, R, output Q); SB_DFFNER _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .E(E), .R(!R)); endmodule
 // module  \$__DFFE_NN1 (input D, C, E, R, output Q); SB_DFFNES _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .E(E), .S(!R)); endmodule
 // module  \$__DFFE_PN0 (input D, C, E, R, output Q); SB_DFFER  _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .E(E), .R(!R)); endmodule
 // module  \$__DFFE_PN1 (input D, C, E, R, output Q); SB_DFFES  _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .E(E), .S(!R)); endmodule
-// 
+//
 // module  \$__DFFE_NP0 (input D, C, E, R, output Q); SB_DFFNER _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .E(E), .R(R)); endmodule
 // module  \$__DFFE_NP1 (input D, C, E, R, output Q); SB_DFFNES _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .E(E), .S(R)); endmodule
 // module  \$__DFFE_PP0 (input D, C, E, R, output Q); SB_DFFER  _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .E(E), .R(R)); endmodule
diff --git a/techlibs/sf2/cells_sim.v b/techlibs/sf2/cells_sim.v
index f967068af..c62748b11 100644
--- a/techlibs/sf2/cells_sim.v
+++ b/techlibs/sf2/cells_sim.v
@@ -1,3 +1,114 @@
+// https://coredocs.s3.amazonaws.com/Libero/12_0_0/Tool/sf2_mlg.pdf
+
+module ADD2 (
+
+	input A, B,
+	output Y
+);
+	assign Y = A & B;
+endmodule
+
+module ADD3 (
+	input A, B, C,
+	output Y
+);
+	assign Y = A & B & C;
+endmodule
+
+module ADD4 (
+	input A, B, C, D,
+	output Y
+);
+	assign Y = A & B & C & D;
+endmodule
+
+module CFG1 (
+	output Y,
+	input A
+);
+	parameter [1:0] INIT = 2'h0;
+	assign Y = INIT >> A;
+endmodule
+
+module CFG2 (
+	output Y,
+	input A,
+	input B
+);
+	parameter [3:0] INIT = 4'h0;
+	assign Y = INIT >> {B, A};
+endmodule
+
+module CFG3 (
+	output Y,
+	input A,
+	input B,
+	input C
+);
+	parameter [7:0] INIT = 8'h0;
+	assign Y = INIT >> {C, B, A};
+endmodule
+
+module CFG4 (
+	output Y,
+	input A,
+	input B,
+	input C,
+	input D
+);
+	parameter [15:0] INIT = 16'h0;
+	assign Y = INIT >> {D, C, B, A};
+endmodule
+
+module BUFF (
+	input A,
+	output Y
+);
+	assign Y = A;
+endmodule
+
+module BUFD (
+	input A,
+	output Y
+);
+	assign Y = A;
+endmodule
+
+module CLKINT (
+	input A,
+	output Y
+);
+	assign Y = A;
+endmodule
+
+module CLKINT_PRESERVE (
+	input A,
+	output Y
+);
+	assign Y = A;
+endmodule
+
+module GCLKINT (
+	input A, EN,
+	output Y
+);
+	assign Y = A & EN;
+endmodule
+
+module RCLKINT (
+	input A,
+	output Y
+);
+	assign Y = A;
+endmodule
+
+module RGCLKINT (
+	input A, EN,
+	output Y
+);
+	assign Y = A & EN;
+endmodule
+
 module SLE (
 	output Q,
 	input ADn,
@@ -36,44 +147,151 @@ module SLE (
 	assign Q = LAT ? q_latch : q_ff;
 endmodule
 
-module CFG1 (
-	output Y,
-	input A
+// module AR1
+// module FCEND_BUFF
+// module FCINIT_BUFF
+// module FLASH_FREEZE
+// module OSCILLATOR
+// module SYSRESET
+// module SYSCTRL_RESET_STATUS
+// module LIVE_PROBE_FB
+// module GCLKBUF
+// module GCLKBUF_DIFF
+// module GCLKBIBUF
+// module DFN1
+// module DFN1C0
+// module DFN1E1
+// module DFN1E1C0
+// module DFN1E1P0
+// module DFN1P0
+// module DLN1
+// module DLN1C0
+// module DLN1P0
+
+module INV (
+	input A,
+	output Y
 );
-	parameter [1:0] INIT = 2'h0;
-	assign Y = INIT >> A;
+	assign Y = !A;
 endmodule
 
-module CFG2 (
-	output Y,
+module INVD (
 	input A,
-	input B
+	output Y
 );
-	parameter [3:0] INIT = 4'h0;
-	assign Y = INIT >> {B, A};
+	assign Y = !A;
 endmodule
 
-module CFG3 (
-	output Y,
-	input A,
-	input B,
-	input C
+module MX2 (
+	input A, B, S,
+	output Y
 );
-	parameter [7:0] INIT = 8'h0;
-	assign Y = INIT >> {C, B, A};
+	assign Y = S ? B : A;
 endmodule
 
-module CFG4 (
-	output Y,
-	input A,
-	input B,
-	input C,
-	input D
+module MX4 (
+	input D0, D1, D2, D3, S0, S1,
+	output Y
 );
-	parameter [15:0] INIT = 16'h0;
-	assign Y = INIT >> {D, C, B, A};
+	assign Y = S1 ? (S0 ? D3 : D2) : (S0 ? D1 : D0);
+endmodule
+
+module NAND2 (
+	input A, B,
+	output Y
+);
+	assign Y = !(A & B);
+endmodule
+
+module NAND3 (
+	input A, B, C,
+	output Y
+);
+	assign Y = !(A & B & C);
+endmodule
+
+module NAND4 (
+	input A, B, C, D,
+	output Y
+);
+	assign Y = !(A & B & C & D);
+endmodule
+
+module NOR2 (
+	input A, B,
+	output Y
+);
+	assign Y = !(A | B);
+endmodule
+
+module NOR3 (
+	input A, B, C,
+	output Y
+);
+	assign Y = !(A | B | C);
+endmodule
+
+module NOR4 (
+	input A, B, C, D,
+	output Y
+);
+	assign Y = !(A | B | C | D);
 endmodule
 
+module OR2 (
+	input A, B,
+	output Y
+);
+	assign Y = A | B;
+endmodule
+
+module OR3 (
+	input A, B, C,
+	output Y
+);
+	assign Y = A | B | C;
+endmodule
+
+module OR4 (
+	input A, B, C, D,
+	output Y
+);
+	assign Y = A | B | C | D;
+endmodule
+
+module XOR2 (
+	input A, B,
+	output Y
+);
+	assign Y = A ^ B;
+endmodule
+
+module XOR3 (
+	input A, B, C,
+	output Y
+);
+	assign Y = A ^ B ^ C;
+endmodule
+
+module XOR4 (
+	input A, B, C, D,
+	output Y
+);
+	assign Y = A ^ B ^ C ^ D;
+endmodule
+
+module XOR8 (
+	input A, B, C, D, E, F, G, H,
+	output Y
+);
+	assign Y = A ^ B ^ C ^ D ^ E ^ F ^ G ^ H;
+endmodule
+
+// module UJTAG
+// module BIBUF
+// module BIBUF_DIFF
+// module CLKBIBUF
+
 module CLKBUF (
 	input PAD,
 	output Y
@@ -81,6 +299,8 @@ module CLKBUF (
 	assign Y = PAD;
 endmodule
 
+// module CLKBUF_DIFF
+
 module INBUF (
 	input PAD,
 	output Y
@@ -88,9 +308,20 @@ module INBUF (
 	assign Y = PAD;
 endmodule
 
+// module INBUF_DIFF
+
 module OUTBUF (
 	input D,
 	output PAD
 );
 	assign PAD = D;
 endmodule
+
+// module OUTBUF_DIFF
+// module TRIBUFF
+// module TRIBUFF_DIFF
+// module DDR_IN
+// module DDR_OUT
+// module RAM1K18
+// module RAM64x18
+// module MACC
diff --git a/techlibs/sf2/sf2_iobs.cc b/techlibs/sf2/sf2_iobs.cc
index 27141430c..3d43332e2 100644
--- a/techlibs/sf2/sf2_iobs.cc
+++ b/techlibs/sf2/sf2_iobs.cc
@@ -23,6 +23,136 @@
 USING_YOSYS_NAMESPACE
 PRIVATE_NAMESPACE_BEGIN
 
+static void handle_iobufs(Module *module, bool clkbuf_mode)
+{
+	SigMap sigmap(module);
+
+	pool<SigBit> clk_bits;
+	pool<SigBit> handled_io_bits;
+	dict<SigBit, SigBit> rewrite_bits;
+	vector<pair<Cell*, SigBit>> pad_bits;
+
+	for (auto cell : module->cells())
+	{
+		if (clkbuf_mode && cell->type == "\\SLE") {
+			for (auto bit : sigmap(cell->getPort("\\CLK")))
+				clk_bits.insert(bit);
+		}
+		if (cell->type.in("\\INBUF", "\\OUTBUF", "\\TRIBUFF", "\\BIBUF", "\\CLKBUF", "\\CLKBIBUF",
+				"\\INBUF_DIFF", "\\OUTBUF_DIFF", "\\BIBUFF_DIFF", "\\TRIBUFF_DIFF", "\\CLKBUF_DIFF",
+				"\\GCLKBUF", "\\GCLKBUF_DIFF", "\\GCLKBIBUF")) {
+			for (auto bit : sigmap(cell->getPort("\\PAD")))
+				handled_io_bits.insert(bit);
+		}
+	}
+
+	for (auto wire : vector<Wire*>(module->wires()))
+	{
+		if (!wire->port_input && !wire->port_output)
+			continue;
+
+		for (int index = 0; index < GetSize(wire); index++)
+		{
+			SigBit bit(wire, index);
+			SigBit canonical_bit = sigmap(bit);
+
+			if (handled_io_bits.count(canonical_bit))
+				continue;
+
+			if (wire->port_input && wire->port_output)
+				log_error("Failed to add buffer for inout port bit %s.\n", log_signal(bit));
+
+			IdString buf_type, buf_port;
+
+			if (wire->port_output) {
+				buf_type = "\\OUTBUF";
+				buf_port = "\\D";
+			} else if (clkbuf_mode && clk_bits.count(canonical_bit)) {
+				buf_type = "\\CLKBUF";
+				buf_port = "\\Y";
+			} else {
+				buf_type = "\\INBUF";
+				buf_port = "\\Y";
+			}
+
+			Cell *c = module->addCell(NEW_ID, buf_type);
+			SigBit new_bit = module->addWire(NEW_ID);
+			c->setPort(buf_port, new_bit);
+			pad_bits.push_back(make_pair(c, bit));
+			rewrite_bits[canonical_bit] = new_bit;
+
+			log("Added %s cell %s for port bit %s.\n", log_id(c->type), log_id(c), log_signal(bit));
+		}
+	}
+
+	auto rewrite_function = [&](SigSpec &s) {
+		for (auto &bit : s) {
+			SigBit canonical_bit = sigmap(bit);
+			if (rewrite_bits.count(canonical_bit))
+				bit = rewrite_bits.at(canonical_bit);
+		}
+	};
+
+	module->rewrite_sigspecs(rewrite_function);
+
+	for (auto &it : pad_bits)
+		it.first->setPort("\\PAD", it.second);
+}
+
+static void handle_clkint(Module *module)
+{
+	SigMap sigmap(module);
+
+	pool<SigBit> clk_bits;
+	vector<SigBit> handled_clk_bits;
+
+	for (auto cell : module->cells())
+	{
+		if (cell->type == "\\SLE") {
+			for (auto bit : sigmap(cell->getPort("\\CLK")))
+				clk_bits.insert(bit);
+		}
+		if (cell->type.in("\\CLKBUF", "\\CLKBIBUF", "\\CLKBUF_DIFF", "\\GCLKBUF", "\\GCLKBUF_DIFF", "\\GCLKBIBUF",
+				"\\CLKINT", "\\CLKINT_PRESERVE", "\\GCLKINT", "\\RCLKINT", "\\RGCLKINT")) {
+			for (auto bit : sigmap(cell->getPort("\\Y")))
+				handled_clk_bits.push_back(bit);
+		}
+	}
+
+	for (auto bit : handled_clk_bits)
+		clk_bits.erase(bit);
+
+	for (auto cell : vector<Cell*>(module->cells()))
+	for (auto &conn : cell->connections())
+	{
+		if (!cell->output(conn.first))
+			continue;
+
+		SigSpec sig = conn.second;
+		bool did_something = false;
+
+		for (auto &bit : sig) {
+			SigBit canonical_bit = sigmap(bit);
+			if (clk_bits.count(canonical_bit)) {
+				Cell *c = module->addCell(NEW_ID, "\\CLKINT");
+				SigBit new_bit = module->addWire(NEW_ID);
+				c->setPort("\\A", new_bit);
+				c->setPort("\\Y", bit);
+				log("Added %s cell %s for clock signal %s.\n", log_id(c->type), log_id(c), log_signal(bit));
+				clk_bits.erase(canonical_bit);
+				did_something = true;
+				bit = new_bit;
+			}
+		}
+
+		if (did_something)
+			cell->setPort(conn.first, sig);
+	}
+
+	for (auto bit : clk_bits)
+		log_error("Failed to insert CLKINT for clock signal %s.\n", log_signal(bit));
+}
+
 struct Sf2IobsPass : public Pass {
 	Sf2IobsPass() : Pass("sf2_iobs", "SF2: insert IO buffers") { }
 	void help() YS_OVERRIDE
@@ -31,20 +161,25 @@ struct Sf2IobsPass : public Pass {
 		log("\n");
 		log("    sf2_iobs [options] [selection]\n");
 		log("\n");
-		log("Add SF2 I/O buffers to top module IOs as needed.\n");
+		log("Add SF2 I/O buffers and global buffers to top module as needed.\n");
+		log("\n");
+		log("    -clkbuf\n");
+		log("        Insert PAD->global_net clock buffers\n");
 		log("\n");
 	}
 	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
 	{
+		bool clkbuf_mode = false;
+
 		log_header(design, "Executing sf2_iobs pass (insert IO buffers).\n");
 
 		size_t argidx;
 		for (argidx = 1; argidx < args.size(); argidx++)
 		{
-			// if (args[argidx] == "-singleton") {
-			// 	singleton_mode = true;
-			// 	continue;
-			// }
+			if (args[argidx] == "-clkbuf") {
+				clkbuf_mode = true;
+				continue;
+			}
 			break;
 		}
 		extra_args(args, argidx, design);
@@ -54,76 +189,8 @@ struct Sf2IobsPass : public Pass {
 		if (module == nullptr)
 			log_cmd_error("No top module found.\n");
 
-		SigMap sigmap(module);
-
-		pool<SigBit> clk_bits;
-		pool<SigBit> handled_io_bits;
-		dict<SigBit, SigBit> rewrite_bits;
-		vector<pair<Cell*, SigBit>> pad_bits;
-
-		for (auto cell : module->cells())
-		{
-			if (cell->type == "\\SLE") {
-				for (auto bit : sigmap(cell->getPort("\\CLK")))
-					clk_bits.insert(bit);
-			}
-			if (cell->type.in("\\INBUF", "\\OUTBUF", "\\CLKBUF")) {
-				for (auto bit : sigmap(cell->getPort("\\PAD")))
-					handled_io_bits.insert(bit);
-			}
-		}
-
-		for (auto wire : vector<Wire*>(module->wires()))
-		{
-			if (!wire->port_input && !wire->port_output)
-				continue;
-
-			for (int index = 0; index < GetSize(wire); index++)
-			{
-				SigBit bit(wire, index);
-				SigBit canonical_bit = sigmap(bit);
-
-				if (handled_io_bits.count(canonical_bit))
-					continue;
-
-				if (wire->port_input && wire->port_output)
-					log_error("Failed to add buffer for inout port bit %s.\n", log_signal(bit));
-
-				IdString buf_type, buf_port;
-
-				if (wire->port_output) {
-					buf_type = "\\OUTBUF";
-					buf_port = "\\D";
-				} else if (clk_bits.count(canonical_bit)) {
-					buf_type = "\\CLKBUF";
-					buf_port = "\\Y";
-				} else {
-					buf_type = "\\INBUF";
-					buf_port = "\\Y";
-				}
-
-				Cell *c = module->addCell(NEW_ID, buf_type);
-				SigBit new_bit = module->addWire(NEW_ID);
-				c->setPort(buf_port, new_bit);
-				pad_bits.push_back(make_pair(c, bit));
-				rewrite_bits[canonical_bit] = new_bit;
-
-				log("Added %s cell %s for port bit %s.\n", log_id(c->type), log_id(c), log_signal(bit));
-			}
-		}
-
-		auto rewrite_function = [&](SigSpec &s) {
-			for (auto &bit : s) {
-				SigBit canonical_bit = sigmap(bit);
-				if (rewrite_bits.count(canonical_bit))
-					bit = rewrite_bits.at(canonical_bit);
-			}
-		};
-
-		module->rewrite_sigspecs(rewrite_function);
-
-		for (auto &it : pad_bits)
-			it.first->setPort("\\PAD", it.second);
+		handle_iobufs(module, clkbuf_mode);
+		handle_clkint(module);
 	}
 } Sf2IobsPass;
 
diff --git a/techlibs/sf2/synth_sf2.cc b/techlibs/sf2/synth_sf2.cc
index bdc20456d..0924df7a6 100644
--- a/techlibs/sf2/synth_sf2.cc
+++ b/techlibs/sf2/synth_sf2.cc
@@ -63,6 +63,9 @@ struct SynthSf2Pass : public ScriptPass
 		log("    -noiobs\n");
 		log("        run synthesis in \"block mode\", i.e. do not insert IO buffers\n");
 		log("\n");
+		log("    -clkbuf\n");
+		log("        insert direct PAD->global_net buffers\n");
+		log("\n");
 		log("    -retime\n");
 		log("        run 'abc' with -dff option\n");
 		log("\n");
@@ -73,7 +76,7 @@ struct SynthSf2Pass : public ScriptPass
 	}
 
 	string top_opt, edif_file, vlog_file, json_file;
-	bool flatten, retime, iobs;
+	bool flatten, retime, iobs, clkbuf;
 
 	void clear_flags() YS_OVERRIDE
 	{
@@ -84,6 +87,7 @@ struct SynthSf2Pass : public ScriptPass
 		flatten = true;
 		retime = false;
 		iobs = true;
+		clkbuf = false;
 	}
 
 	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
@@ -130,6 +134,10 @@ struct SynthSf2Pass : public ScriptPass
 				iobs = false;
 				continue;
 			}
+			if (args[argidx] == "-clkbuf") {
+				clkbuf = true;
+				continue;
+			}
 			break;
 		}
 		extra_args(args, argidx, design);
@@ -201,8 +209,10 @@ struct SynthSf2Pass : public ScriptPass
 
 		if (check_label("map_iobs"))
 		{
-			if (iobs || help_mode)
-				run("sf2_iobs", "(unless -noiobs)");
+			if (help_mode)
+				run("sf2_iobs [-clkbuf]", "(unless -noiobs)");
+			else if (iobs)
+				run(clkbuf ? "sf2_iobs -clkbuf" : "sf2_iobs");
 			run("clean");
 		}
 
diff --git a/techlibs/xilinx/Makefile.inc b/techlibs/xilinx/Makefile.inc
index 887ea27d9..d68f03bb4 100644
--- a/techlibs/xilinx/Makefile.inc
+++ b/techlibs/xilinx/Makefile.inc
@@ -28,7 +28,8 @@ $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/brams_bb.v))
 $(eval $(call add_share_file,share/xilinx,techlibs/xilinx/drams.txt))
 $(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 $(call add_share_file,share/xilinx,techlibs/xilinx/lut2lut.v))
+$(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_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/arith_map.v b/techlibs/xilinx/arith_map.v
index 03719659b..09a5f07e8 100644
--- a/techlibs/xilinx/arith_map.v
+++ b/techlibs/xilinx/arith_map.v
@@ -17,6 +17,9 @@
  *
  */
 
+// ============================================================================
+// LCU
+
 (* techmap_celltype = "$lcu" *)
 module _80_xilinx_lcu (P, G, CI, CO);
 	parameter WIDTH = 2;
@@ -28,10 +31,78 @@ module _80_xilinx_lcu (P, G, CI, CO);
 
 	wire _TECHMAP_FAIL_ = WIDTH <= 2;
 
+	genvar i;
+
+`ifdef _CLB_CARRY
+
+	localparam CARRY4_COUNT = (WIDTH + 3) / 4;
+	localparam MAX_WIDTH    = CARRY4_COUNT * 4;
+	localparam PAD_WIDTH    = MAX_WIDTH - WIDTH;
+
+	wire [MAX_WIDTH-1:0] S  = {{PAD_WIDTH{1'b0}}, P & ~G};
+	wire [MAX_WIDTH-1:0] C  = CO;
+
+	generate for (i = 0; i < CARRY4_COUNT; i = i + 1) begin:slice
+
+		// Partially occupied CARRY4
+		if ((i+1)*4 > WIDTH) begin
+
+			// First one
+			if (i == 0) begin
+				CARRY4 carry4_1st_part
+				(
+				.CYINIT(CI),
+				.CI    (1'd0),
+				.DI    (G [(Y_WIDTH - 1):i*4]),
+				.S     (S [(Y_WIDTH - 1):i*4]),
+				.CO    (CO[(Y_WIDTH - 1):i*4]),
+				);
+			// Another one
+			end else begin
+				CARRY4 carry4_part
+				(
+				.CYINIT(1'd0),
+				.CI    (C [i*4 - 1]),
+				.DI    (G [(Y_WIDTH - 1):i*4]),
+				.S     (S [(Y_WIDTH - 1):i*4]),
+				.CO    (CO[(Y_WIDTH - 1):i*4]),
+				);
+			end
+
+		// Fully occupied CARRY4
+		end else begin
+
+			// First one
+			if (i == 0) begin
+				CARRY4 carry4_1st_full
+				(
+				.CYINIT(CI),
+				.CI    (1'd0),
+				.DI    (G [((i+1)*4 - 1):i*4]),
+				.S     (S [((i+1)*4 - 1):i*4]),
+				.CO    (CO[((i+1)*4 - 1):i*4]),
+				);
+			// Another one
+			end else begin
+				CARRY4 carry4_full
+				(
+				.CYINIT(1'd0),
+				.CI    (C [i*4 - 1]),
+				.DI    (G [((i+1)*4 - 1):i*4]),
+				.S     (S [((i+1)*4 - 1):i*4]),
+				.CO    (CO[((i+1)*4 - 1):i*4]),
+				);
+			end
+
+		end
+
+	end endgenerate
+
+`elsif _EXPLICIT_CARRY
+
 	wire [WIDTH-1:0] C = {CO, CI};
 	wire [WIDTH-1:0] S = P & ~G;
 
-	genvar i;
 	generate for (i = 0; i < WIDTH; i = i + 1) begin:slice
 		MUXCY muxcy (
 			.CI(C[i]),
@@ -40,8 +111,28 @@ module _80_xilinx_lcu (P, G, CI, CO);
 			.O(CO[i])
 		);
 	end endgenerate
+
+`else
+
+	wire [WIDTH-1:0] C = {CO, CI};
+	wire [WIDTH-1:0] S = P & ~G;
+
+	generate for (i = 0; i < WIDTH; i = i + 1) begin:slice
+		MUXCY muxcy (
+			.CI(C[i]),
+			.DI(G[i]),
+			.S(S[i]),
+			.O(CO[i])
+		);
+	end endgenerate
+`endif
+
 endmodule
 
+
+// ============================================================================
+// ALU
+
 (* techmap_celltype = "$alu" *)
 module _80_xilinx_alu (A, B, CI, BI, X, Y, CO);
 	parameter A_SIGNED = 0;
@@ -49,6 +140,8 @@ module _80_xilinx_alu (A, B, CI, BI, X, Y, CO);
 	parameter A_WIDTH = 1;
 	parameter B_WIDTH = 1;
 	parameter Y_WIDTH = 1;
+	parameter _TECHMAP_CONSTVAL_CI_ = 0;
+	parameter _TECHMAP_CONSTMSK_CI_ = 0;
 
 	input [A_WIDTH-1:0] A;
 	input [B_WIDTH-1:0] B;
@@ -66,16 +159,189 @@ module _80_xilinx_alu (A, B, CI, BI, X, Y, CO);
 	wire [Y_WIDTH-1:0] AA = A_buf;
 	wire [Y_WIDTH-1:0] BB = BI ? ~B_buf : B_buf;
 
-	wire [Y_WIDTH-1:0] P = AA ^ BB;
-	wire [Y_WIDTH-1:0] G = AA & BB;
-	wire [Y_WIDTH-1:0] C = {CO, CI};
-	wire [Y_WIDTH-1:0] S = P & ~G;
+	genvar i;
+
+`ifdef _CLB_CARRY
+
+	localparam CARRY4_COUNT = (Y_WIDTH + 3) / 4;
+	localparam MAX_WIDTH    = CARRY4_COUNT * 4;
+	localparam PAD_WIDTH    = MAX_WIDTH - Y_WIDTH;
+
+	wire [MAX_WIDTH-1:0] S  = {{PAD_WIDTH{1'b0}}, AA ^ BB};
+	wire [MAX_WIDTH-1:0] DI = {{PAD_WIDTH{1'b0}}, AA & BB};
+
+	wire [MAX_WIDTH-1:0] C  = CO;
 
 	genvar i;
+	generate for (i = 0; i < CARRY4_COUNT; i = i + 1) begin:slice
+
+		// Partially occupied CARRY4
+		if ((i+1)*4 > Y_WIDTH) begin
+
+			// First one
+			if (i == 0) begin
+				CARRY4 #(.IS_INITIALIZED(1'd1)) carry4_1st_part
+				(
+				.CYINIT(CI),
+				.CI    (1'd0),
+				.DI    (DI[(Y_WIDTH - 1):i*4]),
+				.S     (S [(Y_WIDTH - 1):i*4]),
+				.O     (Y [(Y_WIDTH - 1):i*4]),
+				.CO    (CO[(Y_WIDTH - 1):i*4])
+				);
+			// Another one
+			end else begin
+				CARRY4 carry4_part
+				(
+				.CYINIT(1'd0),
+				.CI    (C [i*4 - 1]),
+				.DI    (DI[(Y_WIDTH - 1):i*4]),
+				.S     (S [(Y_WIDTH - 1):i*4]),
+				.O     (Y [(Y_WIDTH - 1):i*4]),
+				.CO    (CO[(Y_WIDTH - 1):i*4])
+				);
+			end
+
+		// Fully occupied CARRY4
+		end else begin
+
+			// First one
+			if (i == 0) begin
+				CARRY4 #(.IS_INITIALIZED(1'd1)) carry4_1st_full
+				(
+				.CYINIT(CI),
+				.CI    (1'd0),
+				.DI    (DI[((i+1)*4 - 1):i*4]),
+				.S     (S [((i+1)*4 - 1):i*4]),
+				.O     (Y [((i+1)*4 - 1):i*4]),
+				.CO    (CO[((i+1)*4 - 1):i*4])
+				);
+			// Another one
+			end else begin
+				CARRY4 carry4_full
+				(
+				.CYINIT(1'd0),
+				.CI    (C [i*4 - 1]),
+				.DI    (DI[((i+1)*4 - 1):i*4]),
+				.S     (S [((i+1)*4 - 1):i*4]),
+				.O     (Y [((i+1)*4 - 1):i*4]),
+				.CO    (CO[((i+1)*4 - 1):i*4])
+				);
+			end
+
+		end
+
+	end endgenerate
+
+`elsif _EXPLICIT_CARRY
+
+	wire [Y_WIDTH-1:0] S = AA ^ BB;
+	wire [Y_WIDTH-1:0] DI = AA & BB;
+
+	wire CINIT;
+	// Carry chain.
+	//
+	// VPR requires that the carry chain never hit the fabric.	The CO input
+	// to this techmap is the carry outputs for synthesis, e.g. might hit the
+	// fabric.
+	//
+	// So we maintain two wire sets, CO_CHAIN is the carry that is for VPR,
+	// e.g. off fabric dedicated chain.  CO is the carry outputs that are
+	// available to the fabric.
+	wire [Y_WIDTH-1:0] CO_CHAIN;
+	wire [Y_WIDTH-1:0] C = {CO_CHAIN, CINIT};
+
+	// If carry chain is being initialized to a constant, techmap the constant
+	// source.	Otherwise techmap the fabric source.
+	generate for (i = 0; i < 1; i = i + 1) begin:slice
+		CARRY0 #(.CYINIT_FABRIC(1)) carry(
+			.CI_INIT(CI),
+			.DI(DI[0]),
+			.S(S[0]),
+			.CO_CHAIN(CO_CHAIN[0]),
+			.CO_FABRIC(CO[0]),
+			.O(Y[0])
+		);
+	end endgenerate
+
+	generate for (i = 1; i < Y_WIDTH-1; i = i + 1) begin:slice
+		if(i % 4 == 0) begin
+			CARRY0 carry (
+				.CI(C[i]),
+				.DI(DI[i]),
+				.S(S[i]),
+				.CO_CHAIN(CO_CHAIN[i]),
+				.CO_FABRIC(CO[i]),
+				.O(Y[i])
+			);
+		end
+		else
+		begin
+			CARRY carry (
+				.CI(C[i]),
+				.DI(DI[i]),
+				.S(S[i]),
+				.CO_CHAIN(CO_CHAIN[i]),
+				.CO_FABRIC(CO[i]),
+				.O(Y[i])
+			);
+		end
+	end endgenerate
+
+	generate for (i = Y_WIDTH-1; i < Y_WIDTH; i = i + 1) begin:slice
+		if(i % 4 == 0) begin
+			CARRY0 top_of_carry (
+				.CI(C[i]),
+				.DI(DI[i]),
+				.S(S[i]),
+				.CO_CHAIN(CO_CHAIN[i]),
+				.O(Y[i])
+			);
+		end
+		else
+		begin
+			CARRY top_of_carry (
+				.CI(C[i]),
+				.DI(DI[i]),
+				.S(S[i]),
+				.CO_CHAIN(CO_CHAIN[i]),
+				.O(Y[i])
+			);
+		end
+		// Turns out CO_FABRIC and O both use [ABCD]MUX, so provide
+		// a non-congested path to output the top of the carry chain.
+		// Registering the output of the CARRY block would solve this, but not
+		// all designs do that.
+		if((i+1) % 4 == 0) begin
+			CARRY0 carry_output (
+				.CI(CO_CHAIN[i]),
+				.DI(0),
+				.S(0),
+				.O(CO[i])
+			);
+		end
+		else
+		begin
+			CARRY carry_output (
+				.CI(CO_CHAIN[i]),
+				.DI(0),
+				.S(0),
+				.O(CO[i])
+			);
+		end
+	end endgenerate
+
+`else
+
+	wire [Y_WIDTH-1:0] S = AA ^ BB;
+	wire [Y_WIDTH-1:0] DI = AA & BB;
+
+	wire [Y_WIDTH-1:0] C = {CO, CI};
+
 	generate for (i = 0; i < Y_WIDTH; i = i + 1) begin:slice
 		MUXCY muxcy (
 			.CI(C[i]),
-			.DI(G[i]),
+			.DI(DI[i]),
 			.S(S[i]),
 			.O(CO[i])
 		);
@@ -86,6 +352,8 @@ module _80_xilinx_alu (A, B, CI, BI, X, Y, CO);
 		);
 	end endgenerate
 
-	assign X = P;
+`endif
+
+	assign X = S;
 endmodule
 
diff --git a/techlibs/xilinx/cells_map.v b/techlibs/xilinx/cells_map.v
index 0771be0b9..d5801c0fc 100644
--- a/techlibs/xilinx/cells_map.v
+++ b/techlibs/xilinx/cells_map.v
@@ -1,86 +1,20 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
 
-module  \$_DFF_N_ (input D, C, output Q); FDRE #(.INIT(|0), .IS_C_INVERTED(|1), .IS_D_INVERTED(|0), .IS_R_INVERTED(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .R(1'b0)); endmodule
-module  \$_DFF_P_ (input D, C, output Q); FDRE #(.INIT(|0), .IS_C_INVERTED(|0), .IS_D_INVERTED(|0), .IS_R_INVERTED(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .R(1'b0)); endmodule
-
-module  \$_DFFE_NP_ (input D, C, E, output Q); FDRE #(.INIT(|0), .IS_C_INVERTED(|1), .IS_D_INVERTED(|0), .IS_R_INVERTED(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(E), .R(1'b0)); endmodule
-module  \$_DFFE_PP_ (input D, C, E, output Q); FDRE #(.INIT(|0), .IS_C_INVERTED(|0), .IS_D_INVERTED(|0), .IS_R_INVERTED(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(E), .R(1'b0)); endmodule
-
-module  \$_DFF_NN0_ (input D, C, R, output Q); FDCE #(.INIT(|0), .IS_C_INVERTED(|1), .IS_D_INVERTED(|0), .IS_CLR_INVERTED(|1)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR(R)); endmodule
-module  \$_DFF_NP0_ (input D, C, R, output Q); FDCE #(.INIT(|0), .IS_C_INVERTED(|1), .IS_D_INVERTED(|0), .IS_CLR_INVERTED(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR(R)); endmodule
-module  \$_DFF_PN0_ (input D, C, R, output Q); FDCE #(.INIT(|0), .IS_C_INVERTED(|0), .IS_D_INVERTED(|0), .IS_CLR_INVERTED(|1)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR(R)); endmodule
-module  \$_DFF_PP0_ (input D, C, R, output Q); FDCE #(.INIT(|0), .IS_C_INVERTED(|0), .IS_D_INVERTED(|0), .IS_CLR_INVERTED(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR(R)); endmodule
-
-module  \$_DFF_NN1_ (input D, C, R, output Q); FDPE #(.INIT(|0), .IS_C_INVERTED(|1), .IS_D_INVERTED(|0), .IS_PRE_INVERTED(|1)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE(R)); endmodule
-module  \$_DFF_NP1_ (input D, C, R, output Q); FDPE #(.INIT(|0), .IS_C_INVERTED(|1), .IS_D_INVERTED(|0), .IS_PRE_INVERTED(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE(R)); endmodule
-module  \$_DFF_PN1_ (input D, C, R, output Q); FDPE #(.INIT(|0), .IS_C_INVERTED(|0), .IS_D_INVERTED(|0), .IS_PRE_INVERTED(|1)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE(R)); endmodule
-module  \$_DFF_PP1_ (input D, C, R, output Q); FDPE #(.INIT(|0), .IS_C_INVERTED(|0), .IS_D_INVERTED(|0), .IS_PRE_INVERTED(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE(R)); endmodule
-
-`ifndef NO_LUT
-module \$lut (A, Y);
-  parameter WIDTH = 0;
-  parameter LUT = 0;
-
-  input [WIDTH-1:0] A;
-  output Y;
-
-  generate
-    if (WIDTH == 1) begin
-      LUT1 #(.INIT(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]));
-    end else
-    if (WIDTH == 3) begin
-      LUT3 #(.INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
-        .I0(A[0]), .I1(A[1]), .I2(A[2]));
-    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]));
-    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]));
-    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]));
-    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]));
-    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]));
-    end else begin
-      wire _TECHMAP_FAIL_ = 1;
-    end
-  endgenerate
-endmodule
-`endif
+// Empty for now
diff --git a/techlibs/xilinx/cells_sim.v b/techlibs/xilinx/cells_sim.v
index eba17ac9c..ff5ff0726 100644
--- a/techlibs/xilinx/cells_sim.v
+++ b/techlibs/xilinx/cells_sim.v
@@ -1,3 +1,21 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *
+ *  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.
+ *
+ */
 
 // See Xilinx UG953 and UG474 for a description of the cell types below.
 // http://www.xilinx.com/support/documentation/user_guides/ug474_7Series_CLB.pdf
@@ -104,6 +122,29 @@ module CARRY4(output [3:0] CO, O, input CI, CYINIT, input [3:0] DI, S);
   assign CO[3] = S[3] ? CO[2] : DI[3];
 endmodule
 
+`ifdef _EXPLICIT_CARRY
+
+module CARRY0(output CO_CHAIN, CO_FABRIC, O, input CI, CI_INIT, DI, S);
+  parameter CYINIT_FABRIC = 0;
+  wire CI_COMBINE;
+  if(CYINIT_FABRIC) begin
+    assign CI_COMBINE = CI_INIT;
+  end else begin
+    assign CI_COMBINE = CI;
+  end
+  assign CO_CHAIN = S ? CI_COMBINE : DI;
+  assign CO_FABRIC = S ? CI_COMBINE : DI;
+  assign O = S ^ CI_COMBINE;
+endmodule
+
+module CARRY(output CO_CHAIN, CO_FABRIC, O, input CI, DI, S);
+  assign CO_CHAIN = S ? CI : DI;
+  assign CO_FABRIC = S ? CI : DI;
+  assign O = S ^ CI;
+endmodule
+
+`endif
+
 module FDRE (output reg Q, input C, CE, D, R);
   parameter [0:0] INIT = 1'b0;
   parameter [0:0] IS_C_INVERTED = 1'b0;
@@ -156,6 +197,30 @@ module FDPE (output reg Q, input C, CE, D, PRE);
   endcase endgenerate
 endmodule
 
+module FDRE_1 (output reg Q, input C, CE, D, R);
+  parameter [0:0] INIT = 1'b0;
+  initial Q <= INIT;
+  always @(negedge C) if (R) Q <= 1'b0; else if(CE) Q <= D;
+endmodule
+
+module FDSE_1 (output reg Q, input C, CE, D, S);
+  parameter [0:0] INIT = 1'b1;
+  initial Q <= INIT;
+  always @(negedge C) if (S) Q <= 1'b1; else if(CE) Q <= D;
+endmodule
+
+module FDCE_1 (output reg Q, input C, CE, D, CLR);
+  parameter [0:0] INIT = 1'b0;
+  initial Q <= INIT;
+  always @(negedge C, posedge CLR) if (CLR) Q <= 1'b0; else if (CE) Q <= D;
+endmodule
+
+module FDPE_1 (output reg Q, input C, CE, D, PRE);
+  parameter [0:0] INIT = 1'b1;
+  initial Q <= INIT;
+  always @(negedge C, posedge PRE) if (PRE) Q <= 1'b1; else if (CE) Q <= D;
+endmodule
+
 module RAM64X1D (
   output DPO, SPO,
   input  D, WCLK, WE,
diff --git a/techlibs/xilinx/cells_xtra.sh b/techlibs/xilinx/cells_xtra.sh
index 0480410f5..56520ea10 100644
--- a/techlibs/xilinx/cells_xtra.sh
+++ b/techlibs/xilinx/cells_xtra.sh
@@ -7,6 +7,7 @@ function xtract_cell_decl()
 {
 	for dir in $libdir/xeclib $libdir/retarget; do
 		[ -f $dir/$1.v ] || continue
+		[ -z "$2" ] || echo $2
 		egrep '^\s*((end)?module|parameter|input|inout|output|(end)?function|(end)?task)' $dir/$1.v |
 			sed -re '/UNPLACED/ d; /^\s*function/,/endfunction/ d; /^\s*task/,/endtask/ d;
 			         s,//.*,,; s/#?\(.*/(...);/; s/^(input|output|parameter)/ \1/;
@@ -37,10 +38,10 @@ function xtract_cell_decl()
 	xtract_cell_decl BUFMR
 	xtract_cell_decl BUFMRCE
 	xtract_cell_decl BUFR
-	xtract_cell_decl CAPTUREE2
+	xtract_cell_decl CAPTUREE2 "(* keep *)"
 	# xtract_cell_decl CARRY4
 	xtract_cell_decl CFGLUT5
-	xtract_cell_decl DCIRESET
+	xtract_cell_decl DCIRESET "(* keep *)"
 	xtract_cell_decl DNA_PORT
 	xtract_cell_decl DSP48E1
 	xtract_cell_decl EFUSE_USR
@@ -67,10 +68,10 @@ function xtract_cell_decl()
 	xtract_cell_decl IBUFDS_GTE2
 	xtract_cell_decl IBUFDS_IBUFDISABLE
 	xtract_cell_decl IBUFDS_INTERMDISABLE
-	xtract_cell_decl ICAPE2
+	xtract_cell_decl ICAPE2 "(* keep *)"
 	xtract_cell_decl IDDR
 	xtract_cell_decl IDDR_2CLK
-	xtract_cell_decl IDELAYCTRL
+	xtract_cell_decl IDELAYCTRL "(* keep *)"
 	xtract_cell_decl IDELAYE2
 	xtract_cell_decl IN_FIFO
 	xtract_cell_decl IOBUF
@@ -112,10 +113,10 @@ function xtract_cell_decl()
 	xtract_cell_decl PHY_CONTROL
 	xtract_cell_decl PLLE2_ADV
 	xtract_cell_decl PLLE2_BASE
-	xtract_cell_decl PS7
+	xtract_cell_decl PS7 "(* keep *)"
 	xtract_cell_decl PULLDOWN
 	xtract_cell_decl PULLUP
-	# xtract_cell_decl RAM128X1D
+	xtract_cell_decl RAM128X1D
 	xtract_cell_decl RAM128X1S
 	xtract_cell_decl RAM256X1S
 	xtract_cell_decl RAM32M
@@ -124,7 +125,7 @@ function xtract_cell_decl()
 	xtract_cell_decl RAM32X1S_1
 	xtract_cell_decl RAM32X2S
 	xtract_cell_decl RAM64M
-	# xtract_cell_decl RAM64X1D
+	xtract_cell_decl RAM64X1D
 	xtract_cell_decl RAM64X1S
 	xtract_cell_decl RAM64X1S_1
 	xtract_cell_decl RAM64X2S
@@ -136,7 +137,7 @@ function xtract_cell_decl()
 	xtract_cell_decl ROM64X1
 	xtract_cell_decl SRL16E
 	xtract_cell_decl SRLC32E
-	xtract_cell_decl STARTUPE2
+	xtract_cell_decl STARTUPE2 "(* keep *)"
 	xtract_cell_decl USR_ACCESSE2
 	xtract_cell_decl XADC
 } > cells_xtra.new
diff --git a/techlibs/xilinx/cells_xtra.v b/techlibs/xilinx/cells_xtra.v
index 8d8b91ddc..497518d35 100644
--- a/techlibs/xilinx/cells_xtra.v
+++ b/techlibs/xilinx/cells_xtra.v
@@ -114,6 +114,7 @@ module BUFR (...);
     parameter SIM_DEVICE = "7SERIES";
 endmodule
 
+(* keep *)
 module CAPTUREE2 (...);
     parameter ONESHOT = "TRUE";
     input CAP;
@@ -130,6 +131,7 @@ module CFGLUT5 (...);
     input CDI, CE, CLK;
 endmodule
 
+(* keep *)
 module DCIRESET (...);
     output LOCKED;
     input RST;
@@ -2102,6 +2104,7 @@ module IBUFDS_INTERMDISABLE (...);
     input INTERMDISABLE;
 endmodule
 
+(* keep *)
 module ICAPE2 (...);
     parameter [31:0] DEVICE_ID = 32'h04244093;
     parameter ICAP_WIDTH = "X32";
@@ -2149,6 +2152,7 @@ module IDDR_2CLK (...);
     input S;
 endmodule
 
+(* keep *)
 module IDELAYCTRL (...);
     parameter SIM_DEVICE = "7SERIES";
     output RDY;
@@ -3057,6 +3061,7 @@ module PLLE2_BASE (...);
     input RST;
 endmodule
 
+(* keep *)
 module PS7 (...);
     output DMA0DAVALID;
     output DMA0DRREADY;
@@ -3688,6 +3693,17 @@ module PULLUP (...);
     output O;
 endmodule
 
+module RAM128X1D (...);
+    parameter [127:0] INIT = 128'h00000000000000000000000000000000;
+    parameter [0:0] IS_WCLK_INVERTED = 1'b0;
+    output DPO, SPO;
+    input [6:0] A;
+    input [6:0] DPRA;
+    input D;
+    input WCLK;
+    input WE;
+endmodule
+
 module RAM128X1S (...);
     parameter [127:0] INIT = 128'h00000000000000000000000000000000;
     parameter [0:0] IS_WCLK_INVERTED = 1'b0;
@@ -3778,6 +3794,13 @@ module RAM64M (...);
     input WE;
 endmodule
 
+module RAM64X1D (...);
+    parameter [63:0] INIT = 64'h0000000000000000;
+    parameter [0:0] IS_WCLK_INVERTED = 1'b0;
+    output DPO, SPO;
+    input A0, A1, A2, A3, A4, A5, D, DPRA0, DPRA1, DPRA2, DPRA3, DPRA4, DPRA5, WCLK, WE;
+endmodule
+
 module RAM64X1S (...);
     parameter [63:0] INIT = 64'h0000000000000000;
     parameter [0:0] IS_WCLK_INVERTED = 1'b0;
@@ -3840,6 +3863,7 @@ module SRLC32E (...);
     input CE, CLK, D;
 endmodule
 
+(* keep *)
 module STARTUPE2 (...);
     parameter PROG_USR = "FALSE";
     parameter real SIM_CCLK_FREQ = 0.0;
diff --git a/techlibs/xilinx/ff_map.v b/techlibs/xilinx/ff_map.v
new file mode 100644
index 000000000..13beaa6ae
--- /dev/null
+++ b/techlibs/xilinx/ff_map.v
@@ -0,0 +1,42 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *
+ *  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.
+ *
+ */
+
+// ============================================================================
+// FF mapping
+
+`ifndef _NO_FFS
+
+module  \$_DFF_N_   (input D, C, output Q);    FDRE_1 #(.INIT(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .R(1'b0)); endmodule
+module  \$_DFF_P_   (input D, C, output Q);    FDRE   #(.INIT(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .R(1'b0)); endmodule
+
+module  \$_DFFE_NP_ (input D, C, E, output Q); FDRE_1 #(.INIT(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(E),    .R(1'b0)); endmodule
+module  \$_DFFE_PP_ (input D, C, E, output Q); FDRE   #(.INIT(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(E),    .R(1'b0)); endmodule
+
+module  \$_DFF_NN0_ (input D, C, R, output Q); FDCE_1 #(.INIT(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR(!R)); endmodule
+module  \$_DFF_NP0_ (input D, C, R, output Q); FDCE_1 #(.INIT(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR( R)); endmodule
+module  \$_DFF_PN0_ (input D, C, R, output Q); FDCE   #(.INIT(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR(!R)); endmodule
+module  \$_DFF_PP0_ (input D, C, R, output Q); FDCE   #(.INIT(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .CLR( R)); endmodule
+
+module  \$_DFF_NN1_ (input D, C, R, output Q); FDPE_1 #(.INIT(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE(!R)); endmodule
+module  \$_DFF_NP1_ (input D, C, R, output Q); FDPE_1 #(.INIT(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE( R)); endmodule
+module  \$_DFF_PN1_ (input D, C, R, output Q); FDPE   #(.INIT(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE(!R)); endmodule
+module  \$_DFF_PP1_ (input D, C, R, output Q); FDPE   #(.INIT(|0)) _TECHMAP_REPLACE_ (.D(D), .Q(Q), .C(C), .CE(1'b1), .PRE( R)); endmodule
+
+`endif
+
diff --git a/techlibs/xilinx/lut2lut.v b/techlibs/xilinx/lut2lut.v
deleted file mode 100644
index 061ad2041..000000000
--- a/techlibs/xilinx/lut2lut.v
+++ /dev/null
@@ -1,65 +0,0 @@
-module LUT1(output O, input I0);
-  parameter [1:0] INIT = 0;
-  \$lut #(
-    .WIDTH(1),
-    .LUT(INIT)
-  ) _TECHMAP_REPLACE_ (
-    .A(I0),
-    .Y(O)
-  );
-endmodule
-
-module LUT2(output O, input I0, I1);
-  parameter [3:0] INIT = 0;
-  \$lut #(
-    .WIDTH(2),
-    .LUT(INIT)
-  ) _TECHMAP_REPLACE_ (
-    .A({I1, I0}),
-    .Y(O)
-  );
-endmodule
-
-module LUT3(output O, input I0, I1, I2);
-  parameter [7:0] INIT = 0;
-  \$lut #(
-    .WIDTH(3),
-    .LUT(INIT)
-  ) _TECHMAP_REPLACE_ (
-    .A({I2, I1, I0}),
-    .Y(O)
-  );
-endmodule
-
-module LUT4(output O, input I0, I1, I2, I3);
-  parameter [15:0] INIT = 0;
-  \$lut #(
-    .WIDTH(4),
-    .LUT(INIT)
-  ) _TECHMAP_REPLACE_ (
-    .A({I3, I2, I1, I0}),
-    .Y(O)
-  );
-endmodule
-
-module LUT5(output O, input I0, I1, I2, I3, I4);
-  parameter [31:0] INIT = 0;
-  \$lut #(
-    .WIDTH(5),
-    .LUT(INIT)
-  ) _TECHMAP_REPLACE_ (
-    .A({I4, I3, I2, I1, I0}),
-    .Y(O)
-  );
-endmodule
-
-module LUT6(output O, input I0, I1, I2, I3, I4, I5);
-  parameter [63:0] INIT = 0;
-  \$lut #(
-    .WIDTH(6),
-    .LUT(INIT)
-  ) _TECHMAP_REPLACE_ (
-    .A({I5, I4, I3, I2, I1, I0}),
-    .Y(O)
-  );
-endmodule
diff --git a/techlibs/xilinx/lut_map.v b/techlibs/xilinx/lut_map.v
new file mode 100644
index 000000000..d07c59dee
--- /dev/null
+++ b/techlibs/xilinx/lut_map.v
@@ -0,0 +1,94 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *
+ *  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.
+ *
+ */
+
+// ============================================================================
+// LUT mapping
+
+`ifndef _NO_LUTS
+
+module \$lut (A, Y);
+  parameter WIDTH = 0;
+  parameter LUT = 0;
+
+  input [WIDTH-1:0] A;
+  output Y;
+
+  generate
+    if (WIDTH == 1) begin
+      LUT1 #(.INIT(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]));
+    end else
+    if (WIDTH == 3) begin
+      LUT3 #(.INIT(LUT)) _TECHMAP_REPLACE_ (.O(Y),
+        .I0(A[0]), .I1(A[1]), .I2(A[2]));
+    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]));
+    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]));
+    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]));
+    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]));
+    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]));
+    end else begin
+      wire _TECHMAP_FAIL_ = 1;
+    end
+  endgenerate
+endmodule
+
+`endif
+
diff --git a/techlibs/xilinx/synth_xilinx.cc b/techlibs/xilinx/synth_xilinx.cc
index 6c11d885d..805ae8e6e 100644
--- a/techlibs/xilinx/synth_xilinx.cc
+++ b/techlibs/xilinx/synth_xilinx.cc
@@ -63,6 +63,12 @@ struct SynthXilinxPass : public Pass
 		log("        generate an output netlist (and BLIF file) suitable for VPR\n");
 		log("        (this feature is experimental and incomplete)\n");
 		log("\n");
+		log("    -nobram\n");
+		log("        disable infering of block rams\n");
+		log("\n");
+		log("    -nodram\n");
+		log("        disable infering of distributed rams\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");
@@ -90,11 +96,11 @@ struct SynthXilinxPass : public Pass
 		log("    coarse:\n");
 		log("        synth -run coarse\n");
 		log("\n");
-		log("    bram:\n");
+		log("    bram: (only executed when '-nobram' is not given)\n");
 		log("        memory_bram -rules +/xilinx/brams.txt\n");
 		log("        techmap -map +/xilinx/brams_map.v\n");
 		log("\n");
-		log("    dram:\n");
+		log("    dram: (only executed when '-nodram' is not given)\n");
 		log("        memory_bram -rules +/xilinx/drams.txt\n");
 		log("        techmap -map +/xilinx/drams_map.v\n");
 		log("\n");
@@ -104,16 +110,18 @@ struct SynthXilinxPass : public Pass
 		log("        dffsr2dff\n");
 		log("        dff2dffe\n");
 		log("        opt -full\n");
-		log("        techmap -map +/techmap.v -map +/xilinx/arith_map.v\n");
+		log("        techmap -map +/techmap.v -map +/xilinx/arith_map.v -map +/xilinx/ff_map.v\n");
 		log("        opt -fast\n");
 		log("\n");
 		log("    map_luts:\n");
-		log("        abc -luts 2:2,3,6:5,10,20 [-dff]\n");
+		log("        abc -luts 2:2,3,6:5,10,20 [-dff] (without '-vpr' only!)\n");
+		log("        abc -lut 5 [-dff] (with '-vpr' only!)\n");
 		log("        clean\n");
 		log("\n");
 		log("    map_cells:\n");
-		log("        techmap -map +/xilinx/cells_map.v (with -D NO_LUT in vpr mode)\n");
-		log("        dffinit -ff FDRE Q INIT -ff FDCE Q INIT -ff FDPE Q INIT\n");
+		log("        techmap -map +/xilinx/cells_map.v\n");
+		log("        dffinit -ff FDRE   Q INIT -ff FDCE   Q INIT -ff FDPE   Q INIT -ff FDSE   Q INIT \\\n");
+		log("                -ff FDRE_1 Q INIT -ff FDCE_1 Q INIT -ff FDPE_1 Q INIT -ff FDSE_1 Q INIT\n");
 		log("        clean\n");
 		log("\n");
 		log("    check:\n");
@@ -137,6 +145,8 @@ struct SynthXilinxPass : public Pass
 		bool flatten = false;
 		bool retime = false;
 		bool vpr = false;
+		bool nobram = false;
+		bool nodram = false;
 
 		size_t argidx;
 		for (argidx = 1; argidx < args.size(); argidx++)
@@ -173,6 +183,14 @@ struct SynthXilinxPass : public Pass
 				vpr = true;
 				continue;
 			}
+			if (args[argidx] == "-nobram") {
+				nobram = true;
+				continue;
+			}
+			if (args[argidx] == "-nodram") {
+				nodram = true;
+				continue;
+			}
 			break;
 		}
 		extra_args(args, argidx, design);
@@ -187,9 +205,18 @@ struct SynthXilinxPass : public Pass
 
 		if (check_label(active, run_from, run_to, "begin"))
 		{
-			Pass::call(design, "read_verilog -lib +/xilinx/cells_sim.v");
+			if (vpr) {
+				Pass::call(design, "read_verilog -lib -D_EXPLICIT_CARRY +/xilinx/cells_sim.v");
+			} else {
+				Pass::call(design, "read_verilog -lib +/xilinx/cells_sim.v");
+			}
+
 			Pass::call(design, "read_verilog -lib +/xilinx/cells_xtra.v");
-			Pass::call(design, "read_verilog -lib +/xilinx/brams_bb.v");
+
+			if (!nobram) {
+				Pass::call(design, "read_verilog -lib +/xilinx/brams_bb.v");
+			}
+
 			Pass::call(design, stringf("hierarchy -check %s", top_opt.c_str()));
 		}
 
@@ -206,14 +233,18 @@ struct SynthXilinxPass : public Pass
 
 		if (check_label(active, run_from, run_to, "bram"))
 		{
-			Pass::call(design, "memory_bram -rules +/xilinx/brams.txt");
-			Pass::call(design, "techmap -map +/xilinx/brams_map.v");
+			if (!nobram) {
+				Pass::call(design, "memory_bram -rules +/xilinx/brams.txt");
+				Pass::call(design, "techmap -map +/xilinx/brams_map.v");
+			}
 		}
 
 		if (check_label(active, run_from, run_to, "dram"))
 		{
-			Pass::call(design, "memory_bram -rules +/xilinx/drams.txt");
-			Pass::call(design, "techmap -map +/xilinx/drams_map.v");
+			if (!nodram) {
+				Pass::call(design, "memory_bram -rules +/xilinx/drams.txt");
+				Pass::call(design, "techmap -map +/xilinx/drams_map.v");
+			}
 		}
 
 		if (check_label(active, run_from, run_to, "fine"))
@@ -223,7 +254,14 @@ struct SynthXilinxPass : public Pass
 			Pass::call(design, "dffsr2dff");
 			Pass::call(design, "dff2dffe");
 			Pass::call(design, "opt -full");
-			Pass::call(design, "techmap -map +/techmap.v -map +/xilinx/arith_map.v");
+
+			if (vpr) {
+				Pass::call(design, "techmap -map +/techmap.v -map +/xilinx/arith_map.v -map +/xilinx/ff_map.v -D _EXPLICIT_CARRY");
+			} else {
+				Pass::call(design, "techmap -map +/techmap.v -map +/xilinx/arith_map.v -map +/xilinx/ff_map.v");
+			}
+
+			Pass::call(design, "hierarchy -check");
 			Pass::call(design, "opt -fast");
 		}
 
@@ -231,14 +269,14 @@ struct SynthXilinxPass : public Pass
 		{
 			Pass::call(design, "abc -luts 2:2,3,6:5,10,20" + string(retime ? " -dff" : ""));
 			Pass::call(design, "clean");
+			Pass::call(design, "techmap -map +/xilinx/lut_map.v");
 		}
 
 		if (check_label(active, run_from, run_to, "map_cells"))
 		{
 			Pass::call(design, "techmap -map +/xilinx/cells_map.v");
-			if (vpr)
-			    Pass::call(design, "techmap -map +/xilinx/lut2lut.v");
-			Pass::call(design, "dffinit -ff FDRE Q INIT -ff FDCE Q INIT -ff FDPE Q INIT");
+			Pass::call(design, "dffinit -ff FDRE Q INIT -ff FDCE Q INIT -ff FDPE Q INIT -ff FDSE Q INIT "
+					"-ff FDRE_1 Q INIT -ff FDCE_1 Q INIT -ff FDPE_1 Q INIT -ff FDSE_1 Q INIT");
 			Pass::call(design, "clean");
 		}
 
@@ -252,7 +290,7 @@ struct SynthXilinxPass : public Pass
 		if (check_label(active, run_from, run_to, "edif"))
 		{
 			if (!edif_file.empty())
-				Pass::call(design, stringf("write_edif %s", edif_file.c_str()));
+				Pass::call(design, stringf("write_edif -pvector bra %s", edif_file.c_str()));
 		}
 		if (check_label(active, run_from, run_to, "blif"))
 		{
diff --git a/tests/asicworld/xfirrtl b/tests/asicworld/xfirrtl
index c782a2bd6..08bf4ccd8 100644
--- a/tests/asicworld/xfirrtl
+++ b/tests/asicworld/xfirrtl
@@ -6,7 +6,6 @@ code_hdl_models_d_latch_gates.v	combinational loop
 code_hdl_models_dff_async_reset.v	$adff
 code_hdl_models_tff_async_reset.v	$adff
 code_hdl_models_uart.v	$adff
-code_specman_switch_fabric.v	subfield assignment (bits() <= ...)
 code_tidbits_asyn_reset.v	$adff
 code_tidbits_reg_seq_example.v	$adff
 code_verilog_tutorial_always_example.v	empty module
diff --git a/tests/liberty/.gitignore b/tests/liberty/.gitignore
new file mode 100644
index 000000000..e6ec49c4a
--- /dev/null
+++ b/tests/liberty/.gitignore
@@ -0,0 +1,2 @@
+*.log
+test.ys
diff --git a/tests/liberty/busdef.lib b/tests/liberty/busdef.lib
new file mode 100644
index 000000000..b5e3d50b9
--- /dev/null
+++ b/tests/liberty/busdef.lib
@@ -0,0 +1,81 @@
+/********************************************/
+/*                                          */
+/* Supergate cell library for Bench marking */
+/*                                          */
+/* Symbiotic EDA GmbH / Moseley Instruments */
+/* Niels A. Moseley                         */
+/*                                          */
+/* Process: none                            */
+/*                                          */
+/* Date   : 02-11-2018                      */
+/* Version: 1.0                             */
+/*                                          */
+/********************************************/
+
+library(supergate) {
+  technology (cmos);
+  revision : 1.0;
+  
+  time_unit                     : "1ps";
+  pulling_resistance_unit       : "1kohm";  
+  voltage_unit                  : "1V";
+  current_unit                  : "1uA";  
+  
+  capacitive_load_unit(1,ff);
+  
+  default_inout_pin_cap         :  7.0;
+  default_input_pin_cap         :  7.0;
+  default_output_pin_cap        :  0.0;
+  default_fanout_load           :  1.0;
+
+  default_wire_load_capacitance : 0.1;
+  default_wire_load_resistance  : 1.0e-3;
+  default_wire_load_area        : 0.0;
+
+  nom_process                   :  1.0;
+  nom_temperature               : 25.0;
+  nom_voltage                   :  1.2;
+  
+  delay_model                   : generic_cmos;
+  
+    type( IO_bus_3_to_0 ) {
+        base_type : array ;
+        data_type : bit ;
+        bit_width : 4;
+        bit_from : 3 ;
+        bit_to : 0 ;
+        downto : true ;
+    }
+
+    cell (SRAM) {
+        area : 1 ;
+        memory() {
+            type : ram;
+            address_width : 4;
+            word_width : 4;
+        }
+        pin(CE1) {
+            direction : input;
+            capacitance : 0.021;
+            max_transition : 1.024;
+            switch_pin : true;
+        }
+        bus(I1)  {
+            bus_type : IO_bus_3_to_0 ;
+            direction : input;
+            pin (I1[3:0]) {
+                timing() {
+                    related_pin :   "CE1" ;
+                    timing_type : setup_rising ;
+                    rise_constraint (scalar) {
+                        values("0.0507786");
+                    }
+                    fall_constraint (scalar) {
+                        values("0.0507786");
+                    }
+                }
+            }
+        }
+    }
+
+} /* end */
diff --git a/tests/liberty/normal.lib b/tests/liberty/normal.lib
new file mode 100644
index 000000000..4621194dd
--- /dev/null
+++ b/tests/liberty/normal.lib
@@ -0,0 +1,359 @@
+/********************************************/
+/*                                          */
+/* Supergate cell library for Bench marking */
+/*                                          */
+/* Symbiotic EDA GmbH / Moseley Instruments */
+/* Niels A. Moseley                         */
+/*                                          */
+/* Process: none                            */
+/*                                          */
+/* Date   : 02-11-2018                      */
+/* Version: 1.0                             */
+/*                                          */
+/********************************************/
+
+library(supergate) {
+  technology (cmos);
+  revision : 1.0;
+  
+  time_unit                     : "1ps";
+  pulling_resistance_unit       : "1kohm";  
+  voltage_unit                  : "1V";
+  current_unit                  : "1uA";  
+  
+  capacitive_load_unit(1,ff);
+  
+  default_inout_pin_cap         :  7.0;
+  default_input_pin_cap         :  7.0;
+  default_output_pin_cap        :  0.0;
+  default_fanout_load           :  1.0;
+
+  default_wire_load_capacitance : 0.1;
+  default_wire_load_resistance  : 1.0e-3;
+  default_wire_load_area        : 0.0;
+
+  nom_process                   :  1.0;
+  nom_temperature               : 25.0;
+  nom_voltage                   :  1.2;
+  
+  delay_model                   : generic_cmos;
+  
+  /* Inverter */
+  cell (inv) {
+    area : 1;
+    pin(A) {
+      direction : input;
+    }
+    
+    pin(Y) {
+      direction : output;
+      function : "A'";
+    }
+  }
+  
+  /* tri-state inverter */
+  cell (tri_inv) {
+    area : 4;
+    pin(A) {
+      direction : input;    
+    }
+    pin(S) {
+      direction : input;
+    }
+    pin(Z) {
+      direction : output;
+      function  : "A'";
+      three_State : "S'";
+    }
+  }
+  
+  cell (buffer) {
+    area : 5;
+    pin(A) {
+      direction : input;
+    }
+    pin(Y) {
+      direction : output;
+      function : "A";
+    }
+  }  
+  
+  /* 2-input NAND gate */
+  cell (nand2) {
+    area : 3;
+    pin(A) {
+      direction : input;
+    }
+    pin(B) {
+      direction : input;
+    }
+    pin(Y) {
+      direction: output;
+      function : "(A * B)'";
+    }
+  }
+  
+  /* 2-input NOR gate */
+  cell (nor2) {
+    area : 3;
+    pin(A) {
+      direction : input;
+    }
+    pin(B) {
+      direction : input;
+    }
+    pin(Y) {
+      direction: output;
+      function : "(A + B)'";
+    }
+  }
+  
+  /* 2-input XOR */
+  cell (xor2) {
+    area : 6;
+    pin(A) {
+      direction : input;
+    }
+    pin(B) {
+      direction : input;
+    }
+    pin(Y) {
+      direction: output;
+      function : "(A *B') + (A' * B)";
+    }
+  }
+  
+  /* 2-input inverting MUX */
+  cell (imux2) {
+    area : 5;
+    pin(A) {
+      direction : input;
+    }
+    pin(B) {
+      direction : input;
+    }
+    pin(S) {
+      direction : input;
+    } 
+    pin(Y) {
+      direction: output;
+      function : "( (A * S) + (B * S') )'";
+    }
+  }
+  
+  /* D-type flip-flop with asynchronous reset and preset */
+  cell (dff) {
+    area : 6;
+    ff("IQ", "IQN") {
+      next_state : "D";
+      clocked_on : "CLK";
+      clear      : "RESET";
+      preset     : "PRESET";
+      clear_preset_var1 : L;
+      clear_preset_var2 : L;
+    } 
+    pin(D) {
+      direction : input;
+    }
+    pin(CLK) {
+      direction : input;
+    }
+    pin(RESET) {
+      direction : input;
+    }
+    pin(PRESET) {
+      direction : input;
+    }
+    pin(Q) {
+      direction: output;
+      function : "IQ";
+      timing() {
+        timing_type : rising_edge;
+        intrinsic_rise : 65;
+        intrinsic_fall : 65;
+        rise_resistance : 0;
+        fall_resistance : 0; 
+        related_pin : "CLK";
+      }
+      timing () {
+        timing_type : clear;
+        timing_sense : positive_unate;
+        intrinsic_fall : 75;
+        related_pin : "RESET";
+      }
+      timing () {
+        timing_type : preset;
+        timing_sense : negative_unate;
+        intrinsic_rise : 75;
+        related_pin : "PRESET";
+      }      
+    }
+    pin(QN) {
+      direction: output;
+      function : "IQN";
+      timing() {
+        timing_type : rising_edge;
+        intrinsic_rise : 65;
+        intrinsic_fall : 65;
+        rise_resistance : 0;
+        fall_resistance : 0; 
+        related_pin : "CLK";
+      }
+      timing () {
+        timing_type : preset;
+        timing_sense : negative_unate;
+        intrinsic_rise : 75;
+        related_pin : "RESET";
+      }
+      timing () {
+        timing_type : clear;
+        timing_sense : positive_unate;
+        intrinsic_fall : 75;
+        related_pin : "PRESET";
+      }      
+    } 
+  }
+
+  /* Latch */
+  cell(latch) {
+    area : 5;
+    latch ("IQ","IQN") {
+      enable : "G";
+      data_in : "D";
+    }
+
+    pin(D) {
+      direction : input;
+    }
+    pin(G) {
+      direction : input;
+    }
+ 
+    pin(Q) {
+      direction : output;
+      function : "IQ";
+      internal_node : "Q";
+      
+      timing() {
+        timing_type : rising_edge;
+        intrinsic_rise : 65;
+        intrinsic_fall : 65;
+        rise_resistance : 0;
+        fall_resistance : 0;
+        related_pin : "G";
+      }
+      
+      timing() {
+        timing_sense : positive_unate;
+        intrinsic_rise : 65;
+        intrinsic_fall : 65;
+        rise_resistance : 0;
+        fall_resistance : 0;
+        related_pin : "D";
+      }
+    }
+    
+    pin(QN) {
+      direction : output;
+      function : "IQN";
+      internal_node : "QN";
+      
+      timing() {
+        timing_type : rising_edge;
+        intrinsic_rise : 65;
+        intrinsic_fall : 65;
+        rise_resistance : 0;
+        fall_resistance : 0;
+        related_pin : "G";
+      }
+      
+      timing() {
+        timing_sense : negative_unate;
+        intrinsic_rise : 65;
+        intrinsic_fall : 65;
+        rise_resistance : 0;
+        fall_resistance : 0;
+        related_pin : "D";
+      }
+    }
+  }
+
+  /* 3 input AND-OR-INVERT gate */
+  cell (aoi211) {
+    area : 3;
+    pin(A) {
+      direction : input;
+    }
+    pin(B) {
+      direction : input;
+    }
+    pin(C) {
+      direction : input;
+    }    
+    pin(Y) {
+      direction: output;
+      function : "((A * B) + C)'";
+    }
+  }
+
+
+  /* 3 input OR-AND-INVERT gate */
+  cell (oai211) {
+    area : 3;
+    pin(A) {
+      direction : input;
+    }
+    pin(B) {
+      direction : input;
+    }
+    pin(C) {
+      direction : input;
+    }    
+    pin(Y) {
+      direction: output;
+      function : "((A + B) * C)'";
+    }
+  }
+
+  /* half adder */
+  cell (halfadder) {
+    area : 5;
+    pin(A) {
+      direction : input;
+    }
+    pin(B) {
+      direction : input;
+    }
+    pin(C) {
+      direction : output;
+      function  : "(A * B)";
+    }    
+    pin(Y) {
+      direction: output;
+      function : "(A *B') + (A' * B)";
+    }    
+  }
+
+  /* full adder */
+  cell (fulladder) {
+    area : 8;
+    pin(A) {
+      direction : input;
+    }
+    pin(B) {
+      direction : input;
+    }
+    pin(CI) {
+      direction : input;
+    }    
+    pin(CO) {
+      direction : output;
+      function : "(((A * B)+(B * CI))+(CI * A))";
+    }
+    pin(Y) {
+      direction: output;
+      function : "((A^B)^CI)";
+    }    
+  }
+
+} /* end */
diff --git a/tests/liberty/processdefs.lib b/tests/liberty/processdefs.lib
new file mode 100644
index 000000000..37a6bbaf8
--- /dev/null
+++ b/tests/liberty/processdefs.lib
@@ -0,0 +1,48 @@
+/********************************************/
+/*                                          */
+/* Supergate cell library for Bench marking */
+/*                                          */
+/* Symbiotic EDA GmbH / Moseley Instruments */
+/* Niels A. Moseley                         */
+/*                                          */
+/* Process: none                            */
+/*                                          */
+/* Date   : 25-03-2019                      */
+/* Version: 1.0                             */
+/*                                          */
+/********************************************/
+
+library(processdefs) {
+    technology (cmos);
+    revision : 1.0;
+
+    time_unit                     : "1ps";
+    pulling_resistance_unit       : "1kohm";  
+    voltage_unit                  : "1V";
+    current_unit                  : "1uA";  
+
+    capacitive_load_unit(1,ff);
+
+    default_inout_pin_cap         :  7.0;
+    default_input_pin_cap         :  7.0;
+    default_output_pin_cap        :  0.0;
+    default_fanout_load           :  1.0;
+
+    default_wire_load_capacitance : 0.1;
+    default_wire_load_resistance  : 1.0e-3;
+    default_wire_load_area        : 0.0;
+
+    nom_process                   :  1.0;
+    nom_temperature               : 25.0;
+    nom_voltage                   :  1.2;
+
+    delay_model                   : generic_cmos;
+    
+    define_cell_area(bond_pads,pad_slots)
+    input_voltage(cmos) {
+        vil : 0.3 * VDD ;
+        vih : 0.7 * VDD ;
+        vimin : -0.5 ;
+        vimax : VDD + 0.5 ;
+    }
+}
diff --git a/tests/liberty/run-test.sh b/tests/liberty/run-test.sh
new file mode 100755
index 000000000..7e2ed2370
--- /dev/null
+++ b/tests/liberty/run-test.sh
@@ -0,0 +1,10 @@
+#!/bin/bash
+set -e
+
+for x in *.lib; do
+	echo "Running $x.."
+    echo "read_verilog small.v" > test.ys
+    echo "synth -top small" >> test.ys
+    echo "dfflibmap -liberty ${x}" >> test.ys
+	../../yosys -ql ${x%.lib}.log -s test.ys
+done
diff --git a/tests/liberty/semicolextra.lib b/tests/liberty/semicolextra.lib
new file mode 100644
index 000000000..6a7fa77cc
--- /dev/null
+++ b/tests/liberty/semicolextra.lib
@@ -0,0 +1,48 @@
+/*
+
+	Test case for https://www.reddit.com/r/yosys/comments/b5texg/yosys_fails_to_parse_apparentlycorrect_liberty/
+
+	fall_constraint (SETUP_HOLD) formatting.
+
+*/
+
+library(supergate) {
+  technology (cmos);
+  revision : 1.0;
+
+    cell (DFF) {
+        cell_footprint : dff;
+        area : 50;
+        pin(D) {
+            direction : input;
+            capacitance : 0.002;
+            timing() {
+                related_pin : "CK";
+                timing_type : setup_rising;
+
+                fall_constraint (SETUP_HOLD) { values ("0.4000, 0.3000, 0.2000, 0.1000, 0.0000", \
+                    "0.4000, 0.3000, 0.2000, 0.1000, 0.000", \
+                    "0.5000, 0.4000, 0.3000, 0.2000, 0.0000", \
+                    "0.7000, 0.6000, 0.5000, 0.4000, 0.2000", \
+                    "1.0000, 1.0000, 0.9000, 0.8000, 0.6000"); };
+            }
+        }	
+
+        pin(CK) {
+            direction : input;
+            clock : true;
+            capacitance : 0.00290;
+        }
+
+        ff(IQ,IQN) {
+            clocked_on : "CK";
+            next_state : "D";
+        }
+        pin(Q) {
+            direction : output;
+            capacitance : 0.003;
+            max_capacitance : 0.3;
+        }
+        cell_leakage_power : 0.3;
+    }
+}
diff --git a/tests/liberty/semicolmissing.lib b/tests/liberty/semicolmissing.lib
new file mode 100644
index 000000000..f7c20750a
--- /dev/null
+++ b/tests/liberty/semicolmissing.lib
@@ -0,0 +1,72 @@
+/********************************************/
+/*                                          */
+/* Supergate cell library for Bench marking */
+/*                                          */
+/* Symbiotic EDA GmbH / Moseley Instruments */
+/* Niels A. Moseley                         */
+/*                                          */
+/* Process: none                            */
+/*                                          */
+/* Date   : 24-03-2019                      */
+/* Version: 1.0                             */
+/* Version: 1.1 - Removed semicolons in     */
+/*                full adder                */
+/*                                          */
+/********************************************/
+
+/* 
+    semi colon is missing in full-adder specification
+    some TSMC liberty files are formatted this way..
+*/
+
+library(supergate) {
+  technology (cmos);
+  revision : 1.0;
+  
+  time_unit                     : "1ps";
+  pulling_resistance_unit       : "1kohm";  
+  voltage_unit                  : "1V";
+  current_unit                  : "1uA";  
+  
+  capacitive_load_unit(1,ff);
+  
+  default_inout_pin_cap         :  7.0;
+  default_input_pin_cap         :  7.0;
+  default_output_pin_cap        :  0.0;
+  default_fanout_load           :  1.0;
+
+  default_wire_load_capacitance : 0.1;
+  default_wire_load_resistance  : 1.0e-3;
+  default_wire_load_area        : 0.0;
+
+  nom_process                   :  1.0;
+  nom_temperature               : 25.0;
+  nom_voltage                   :  1.2;
+  
+  delay_model                   : generic_cmos;
+  
+  /* full adder */
+  cell (fulladder) {
+    area : 8
+    pin(A) {
+      direction : input
+    }
+    pin(B) {
+      direction : input
+    }
+    pin(CI) {
+      direction : input
+    }    
+    pin(CO) {
+      direction : output
+      function : "(((A * B)+(B * CI))+(CI * A))"
+    }
+    pin(Y) {
+      direction: output
+      function : "((A^B)^CI)"
+    }    
+  }
+
+} /* end */
+
+
diff --git a/tests/liberty/small.v b/tests/liberty/small.v
new file mode 100644
index 000000000..bd94be4fc
--- /dev/null
+++ b/tests/liberty/small.v
@@ -0,0 +1,16 @@
+/** small, meaningless design to test loading of liberty files */
+
+module small
+(
+    input clk,
+    output reg[7:0] count
+);
+
+initial count = 0;
+
+always @ (posedge clk) 
+begin
+    count <= count + 1'b1;
+end
+
+endmodule
diff --git a/tests/simple/generate.v b/tests/simple/generate.v
index 24eb4462c..3c55682cb 100644
--- a/tests/simple/generate.v
+++ b/tests/simple/generate.v
@@ -90,5 +90,61 @@ generate
 		endcase
 	end
 endgenerate
+endmodule
+
+// ------------------------------------------
+
+module gen_test4(a, b);
+
+input [3:0] a;
+output [3:0] b;
+
+genvar i;
+generate
+	for (i=0; i < 3; i=i+1) begin : foo
+		localparam PREV = i - 1;
+		wire temp;
+		if (i == 0)
+			assign temp = a[0];
+		else
+			assign temp = foo[PREV].temp & a[i];
+		assign b[i] = temp;
+	end
+endgenerate
+endmodule
+
+// ------------------------------------------
+
+module gen_test5(input_bits, out);
+
+parameter WIDTH = 256;
+parameter CHUNK = 4;
 
+input [WIDTH-1:0] input_bits;
+output out;
+
+genvar step, i, j;
+generate
+	for (step = 1; step <= WIDTH; step = step * CHUNK) begin : steps
+		localparam PREV = step / CHUNK;
+		localparam DIM = WIDTH / step;
+		for (i = 0; i < DIM; i = i + 1) begin : outer
+			localparam LAST_START = i * CHUNK;
+			for (j = 0; j < CHUNK; j = j + 1) begin : inner
+				wire temp;
+				if (step == 1)
+					assign temp = input_bits[i];
+				else if (j == 0)
+					assign temp = steps[PREV].outer[LAST_START].val;
+				else
+					assign temp
+						= steps[step].outer[i].inner[j-1].temp
+						& steps[PREV].outer[LAST_START + j].val;
+			end
+			wire val;
+			assign val = steps[step].outer[i].inner[CHUNK - 1].temp;
+		end
+	end
+endgenerate
+assign out = steps[WIDTH].outer[0].val;
 endmodule
diff --git a/tests/simple/task_func.v b/tests/simple/task_func.v
index fa50c1d5c..f6e902f63 100644
--- a/tests/simple/task_func.v
+++ b/tests/simple/task_func.v
@@ -120,3 +120,22 @@ module task_func_test04(input [7:0] in, output [7:0] out1, out2, out3, out4);
 	assign out3 = test3(in);
 	assign out4 = test4(in);
 endmodule
+
+// -------------------------------------------------------------------
+
+// https://github.com/YosysHQ/yosys/issues/857
+module task_func_test05(data_in,data_out,clk);
+	output reg data_out;
+	input data_in;
+	input clk;
+
+	task myTask;
+		output out;
+		input in;
+		out = in;
+	endtask
+
+	always @(posedge clk) begin
+		myTask(data_out,data_in);
+	end
+endmodule
diff --git a/tests/simple/xfirrtl b/tests/simple/xfirrtl
index 00e89b389..50d693513 100644
--- a/tests/simple/xfirrtl
+++ b/tests/simple/xfirrtl
@@ -1,6 +1,7 @@
 # This file contains the names of verilog files to exclude from verilog to FIRRTL regression tests due to known failures.
 arraycells.v	inst id[0] of
 dff_different_styles.v
+dff_init.v	Initial value not supported
 generate.v	combinational loop
 hierdefparam.v	inst id[0] of
 i2c_master_tests.v   $adff
@@ -12,7 +13,6 @@ multiplier.v	inst id[0] of
 muxtree.v	drops modules
 omsp_dbg_uart.v	$adff
 operators.v	$pow
-paramods.v	subfield assignment (bits() <= ...)
 partsel.v	drops modules
 process.v	drops modules
 realexpr.v	drops modules
diff --git a/tests/sva/extnets.sv b/tests/sva/extnets.sv
new file mode 100644
index 000000000..47312de7a
--- /dev/null
+++ b/tests/sva/extnets.sv
@@ -0,0 +1,22 @@
+module top(input i, output o);
+	A A();
+	B B();
+	assign A.i = i;
+	assign o = B.o;
+	always @* assert(o == i);
+endmodule
+
+module A;
+	wire i, y;
+`ifdef FAIL
+	assign B.x = i;
+`else
+	assign B.x = !i;
+`endif
+	assign y = !B.y;
+endmodule
+
+module B;
+	wire x, y, o;
+	assign y = x, o = A.y;
+endmodule
diff --git a/tests/tools/autotest.sh b/tests/tools/autotest.sh
index 13c25432f..99768b0ec 100755
--- a/tests/tools/autotest.sh
+++ b/tests/tools/autotest.sh
@@ -8,7 +8,7 @@ verbose=false
 keeprunning=false
 makejmode=false
 frontend="verilog"
-backend_opts="-noattr -noexpr"
+backend_opts="-noattr -noexpr -siminit"
 autotb_opts=""
 include_opts=""
 xinclude_opts=""
@@ -49,7 +49,7 @@ while getopts xmGl:wkjvref:s:p:n:S:I:-: opt; do
 		r)
 			backend_opts="$backend_opts -norename" ;;
 		e)
-			backend_opts="$( echo " $backend_opts " | sed 's, -noexpr ,,; s,^ ,,; s, $,,;'; )" ;;
+			backend_opts="$( echo " $backend_opts " | sed 's, -noexpr , ,; s,^ ,,; s, $,,;'; )" ;;
 		f)
 			frontend="$OPTARG" ;;
 		s)
@@ -181,7 +181,7 @@ do
 			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
-				$firrtl2verilog -i ${bn}_ref.fir -o ${bn}_ref.fir.v  -X verilog
+				$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
 			fi