add support for initializing registers and memories to the functional backend

backends/functional/cxx.cc

@@ -72,8 +72,8 @@ struct CxxStruct {
 	std::string name;
 	dict<IdString, CxxType> types;
 	CxxScope<IdString> scope;
-  CxxStruct(std::string name)
+	CxxStruct(std::string name) : name(name)
-    : name(name) {
+	{
 		scope.reserve("fn");
 		scope.reserve("visit");
 	}
@@ -98,6 +98,19 @@ struct CxxStruct {
 	}
 };
 
+std::string cxx_const(RTLIL::Const const &value) {
+	std::stringstream ss;
+	ss << "Signal<" << value.size() << ">(" << std::hex << std::showbase;
+	if(value.size() > 32) ss << "{";
+	for(int i = 0; i < value.size(); i += 32) {
+		if(i > 0) ss << ", ";
+		ss << value.extract(i, 32).as_int();
+	}
+	if(value.size() > 32) ss << "}";
+	ss << ")";
+	return ss.str();
+}
+
 template<class NodePrinter> struct CxxPrintVisitor : public FunctionalIR::AbstractVisitor<void> {
 	using Node = FunctionalIR::Node;
 	CxxWriter &f;
@@ -136,20 +149,7 @@ template<class NodePrinter> struct CxxPrintVisitor : public FunctionalIR::Abstra
 	void logical_shift_right(Node, Node a, Node b) override { print("{} >> {}", a, b); }
 	void arithmetic_shift_right(Node, Node a, Node b) override { print("{}.arithmetic_shift_right({})", a, b); }
 	void mux(Node, Node a, Node b, Node s) override { print("{2}.any() ? {1} : {0}", a, b, s); }
-	void constant(Node, RTLIL::Const value) override {
+	void constant(Node, RTLIL::Const const & value) override { print("{}", cxx_const(value)); }
-		std::stringstream ss;
-		bool multiple = value.size() > 32;
-		ss << "Signal<" << value.size() << ">(" << std::hex << std::showbase;
-		if(multiple) ss << "{";
-		while(value.size() > 32) {
-			ss << value.as_int() << ", ";
-			value = value.extract(32, value.size() - 32);
-		}
-		ss << value.as_int();
-		if(multiple) ss << "}";
-		ss << ")";
-		print("{}", ss.str());
-	}
 	void input(Node, IdString name) override { print("input.{}", input_struct[name]); }
 	void state(Node, IdString name) override { print("current_state.{}", state_struct[name]); }
 	void memory_read(Node, Node mem, Node addr) override { print("{}.read({})", mem, addr); }
@@ -184,8 +184,24 @@ struct CxxModule {
 		output_struct.print(f);
 		state_struct.print(f);
 		f.print("\tstatic void eval(Inputs const &, Outputs &, State const &, State &);\n");
+		f.print("\tstatic void initialize(State &);\n");
 		f.print("}};\n\n");
 	}
+	void write_initial_def(CxxWriter &f) {
+		f.print("void {0}::initialize({0}::State &state)\n{{\n", module_name);
+		for (auto [name, sort] : ir.state()) {
+			if (sort.is_signal())
+				f.print("\tstate.{} = {};\n", state_struct[name], cxx_const(ir.get_initial_state_signal(name)));
+			else if (sort.is_memory()) {
+				const auto &contents = ir.get_initial_state_memory(name);
+				f.print("\tstate.{}.fill({});\n", state_struct[name], cxx_const(contents.default_value()));
+				for(auto range : contents)
+					for(auto addr = range.base(); addr < range.limit(); addr++)
+						f.print("\tstate.{}[{}] = {};\n", state_struct[name], addr, cxx_const(range[addr]));
+			}
+		}
+		f.print("}}\n\n");
+	}
 	void write_eval_def(CxxWriter &f) {
 		f.print("void {0}::eval({0}::Inputs const &input, {0}::Outputs &output, {0}::State const &current_state, {0}::State &next_state)\n{{\n", module_name);
 		CxxScope<int> locals;
@@ -204,7 +220,7 @@ struct CxxModule {
 			f.print("\tnext_state.{} = {};\n", state_struct[name], node_name(ir.get_state_next_node(name)));
 		for (auto [name, sort] : ir.outputs())
 			f.print("\toutput.{} = {};\n", output_struct[name], node_name(ir.get_output_node(name)));
-		f.print("}}\n");
+		f.print("}}\n\n");
 	}
 };
 
@@ -225,6 +241,7 @@ struct FunctionalCxxBackend : public Backend
 		mod.write_header(f);
 		mod.write_struct_def(f);
 		mod.write_eval_def(f);
+		mod.write_initial_def(f);
 	}
 
 	void execute(std::ostream *&f, std::string filename, std::vector<std::string> args, RTLIL::Design *design) override

backends/functional/cxx_runtime/sim.h

@@ -410,6 +410,9 @@ public:
         ret._contents[addr.template as_numeric<size_t>()] = data;
         return ret;
     }
+    // mutating methods for initializing a state
+    void fill(Signal<d> data) { _contents.fill(data); }
+    Signal<d> &operator[](Signal<a> addr) { return _contents[addr.template as_numeric<size_t>()]; }
 };
 
 #endif

backends/functional/smtlib.cc

@@ -109,6 +109,13 @@ public:
 	}
 };
 
+std::string smt_const(RTLIL::Const const &c) {
+	std::string s = "#b";
+	for(int i = c.size(); i-- > 0; )
+		s += c[i] == State::S1 ? '1' : '0';
+	return s;
+}
+
 struct SmtPrintVisitor : public FunctionalIR::AbstractVisitor<SExpr> {
 	using Node = FunctionalIR::Node;
 	std::function<SExpr(Node)> n;
@@ -117,13 +124,6 @@ struct SmtPrintVisitor : public FunctionalIR::AbstractVisitor<SExpr> {
 
 	SmtPrintVisitor(SmtStruct &input_struct, SmtStruct &state_struct) : input_struct(input_struct), state_struct(state_struct) {}
 
-	std::string literal(RTLIL::Const c) {
-		std::string s = "#b";
-		for(int i = c.size(); i-- > 0; )
-			s += c[i] == State::S1 ? '1' : '0';
-		return s;
-	}
-
 	SExpr from_bool(SExpr &&arg) {
 		return list("ite", std::move(arg), "#b1", "#b0");
 	}
@@ -149,8 +149,8 @@ struct SmtPrintVisitor : public FunctionalIR::AbstractVisitor<SExpr> {
 	SExpr bitwise_xor(Node, Node a, Node b) override { return list("bvxor", n(a), n(b)); }
 	SExpr bitwise_not(Node, Node a) override { return list("bvnot", n(a)); }
 	SExpr unary_minus(Node, Node a) override { return list("bvneg", n(a)); }
-	SExpr reduce_and(Node, Node a) override { return from_bool(list("=", n(a), literal(RTLIL::Const(State::S1, a.width())))); }
+	SExpr reduce_and(Node, Node a) override { return from_bool(list("=", n(a), smt_const(RTLIL::Const(State::S1, a.width())))); }
-	SExpr reduce_or(Node, Node a) override { return from_bool(list("distinct", n(a), literal(RTLIL::Const(State::S0, a.width())))); }
+	SExpr reduce_or(Node, Node a) override { return from_bool(list("distinct", n(a), smt_const(RTLIL::Const(State::S0, a.width())))); }
 	SExpr reduce_xor(Node, Node a) override {
 		vector<SExpr> s { "bvxor" };
 		for(int i = 0; i < a.width(); i++)
@@ -174,7 +174,7 @@ struct SmtPrintVisitor : public FunctionalIR::AbstractVisitor<SExpr> {
 	SExpr logical_shift_right(Node, Node a, Node b) override { return list("bvlshr", n(a), extend(n(b), b.width(), a.width())); }
 	SExpr arithmetic_shift_right(Node, Node a, Node b) override { return list("bvashr", n(a), extend(n(b), b.width(), a.width())); }
 	SExpr mux(Node, Node a, Node b, Node s) override { return list("ite", to_bool(n(s)), n(b), n(a)); }
-	SExpr constant(Node, RTLIL::Const value) override { return literal(value); }
+	SExpr constant(Node, RTLIL::Const const &value) override { return smt_const(value); }
 	SExpr memory_read(Node, Node mem, Node addr) override { return list("select", n(mem), n(addr)); }
 	SExpr memory_write(Node, Node mem, Node addr, Node data) override { return list("store", n(mem), n(addr), n(data)); }
 
@@ -199,6 +199,7 @@ struct SmtModule {
 		, output_struct(scope.unique_name(module->name.str() + "_Outputs"), scope)
 		, state_struct(scope.unique_name(module->name.str() + "_State"), scope)
 	{
+		scope.reserve(name + "-initial");
 		for (const auto &input : ir.inputs())
 			input_struct.insert(input.first, input.second);
 		for (const auto &output : ir.outputs())
@@ -207,18 +208,8 @@ struct SmtModule {
 			state_struct.insert(state.first, state.second);
 	}
 
-	void write(std::ostream &out)
+	void write_eval(SExprWriter &w)
 	{
-		SExprWriter w(out);
-
-		input_struct.write_definition(w);
-		output_struct.write_definition(w);
-		state_struct.write_definition(w);
-
-		w << list("declare-datatypes",
-			list(list("Pair", 2)),
-			list(list("par", list("X", "Y"), list(list("pair", list("first", "X"), list("second", "Y"))))));
-
 		w.push();
 		w.open(list("define-fun", name,
 			list(list("inputs", input_struct.name),
@@ -245,6 +236,39 @@ struct SmtModule {
 		state_struct.write_value(w, [&](IdString name) { return node_to_sexpr(ir.get_state_next_node(name)); });
 		w.pop();
 	}
+
+	void write_initial(SExprWriter &w)
+	{
+		std::string initial = name + "-initial";
+		w << list("declare-const", initial, state_struct.name);
+		for (const auto &[name, sort] : ir.state()) {
+			if(sort.is_signal())
+				w << list("assert", list("=", state_struct.access(initial, name), smt_const(ir.get_initial_state_signal(name))));
+			else if(sort.is_memory()) {
+				auto contents = ir.get_initial_state_memory(name);
+				for(int i = 0; i < 1<<sort.addr_width(); i++) {
+					auto addr = smt_const(RTLIL::Const(i, sort.addr_width()));
+					w << list("assert", list("=", list("select", state_struct.access(initial, name), addr), smt_const(contents[i])));
+				}
+			}
+		}
+	}
+
+	void write(std::ostream &out)
+	{    
+		SExprWriter w(out);
+
+		input_struct.write_definition(w);
+		output_struct.write_definition(w);
+		state_struct.write_definition(w);
+
+		w << list("declare-datatypes",
+			list(list("Pair", 2)),
+			list(list("par", list("X", "Y"), list(list("pair", list("first", "X"), list("second", "Y"))))));
+		
+		write_eval(w);
+		write_initial(w);
+	}
 };
 
 struct FunctionalSmtBackend : public Backend {

backends/functional/test_generic.cc

@@ -19,10 +19,100 @@
 
 #include "kernel/yosys.h"
 #include "kernel/functionalir.h"
+#include <random>
 
 USING_YOSYS_NAMESPACE
 PRIVATE_NAMESPACE_BEGIN
 
+struct MemContentsTest {
+	int addr_width, data_width;
+	MemContents state;
+	using addr_t = MemContents::addr_t;
+	std::map<addr_t, RTLIL::Const> reference;
+	MemContentsTest(int addr_width, int data_width) : addr_width(addr_width), data_width(data_width), state(addr_width, data_width, RTLIL::Const(State::S0, data_width))  {}
+	void check() {
+		state.check();
+		for(auto addr = 0; addr < (1<<addr_width); addr++) {
+			auto it = reference.find(addr);
+			if(it != reference.end()) {
+				if(state.count_range(addr, addr + 1) != 1) goto error;
+				if(it->second != state[addr]) goto error;
+			} else {
+				if(state.count_range(addr, addr + 1) != 0) goto error;
+			}
+		}
+		return;
+		error:
+		printf("FAIL\n");
+		int digits = (data_width + 3) / 4;
+		
+		for(auto addr = 0; addr < (1<<addr_width); addr++) {
+			if(addr % 8 == 0) printf("%.8x   ", addr);
+			auto it = reference.find(addr);
+			bool ref_def = it != reference.end();
+			RTLIL::Const ref_value = ref_def ? it->second : state.default_value();
+			std::string ref_string = stringf("%.*x", digits, ref_value.as_int());
+			bool sta_def = state.count_range(addr, addr + 1) == 1;
+			RTLIL::Const sta_value = state[addr];
+			std::string sta_string = stringf("%.*x", digits, sta_value.as_int());
+			if(ref_def && sta_def) {
+				if(ref_value == sta_value) printf("%s%s", ref_string.c_str(), string(digits, ' ').c_str());
+				else printf("%s%s", ref_string.c_str(), sta_string.c_str());
+			} else if(ref_def) {
+				printf("%s%s", ref_string.c_str(), string(digits, 'M').c_str());
+			} else if(sta_def) {
+				printf("%s%s", sta_string.c_str(), string(digits, 'X').c_str());
+			} else {
+				printf("%s", string(2*digits, ' ').c_str());
+			}
+			printf(" ");
+			if(addr % 8 == 7) printf("\n");
+		}
+		printf("\n");
+		//log_abort();
+	}
+	void clear_range(addr_t begin_addr, addr_t end_addr) {
+		for(auto addr = begin_addr; addr != end_addr; addr++)
+			reference.erase(addr);
+		state.clear_range(begin_addr, end_addr);
+		check();
+	}
+	void insert_concatenated(addr_t addr, RTLIL::Const const &values) {
+		addr_t words = ((addr_t) values.size() + data_width - 1) / data_width;
+		for(addr_t i = 0; i < words; i++) {
+			reference.erase(addr + i);
+			reference.emplace(addr + i, values.extract(i * data_width, data_width));
+		}
+		state.insert_concatenated(addr, values);
+		check();
+	}
+	template<typename Rnd> void run(Rnd &rnd, int n) {
+		std::uniform_int_distribution<addr_t> addr_dist(0, (1<<addr_width) - 1);
+		std::poisson_distribution<addr_t> length_dist(10);
+		std::uniform_int_distribution<uint64_t> data_dist(0, ((uint64_t)1<<data_width) - 1);
+		while(n-- > 0) {
+			addr_t low = addr_dist(rnd);
+			//addr_t length = std::min((1<<addr_width) - low, length_dist(rnd));
+			//addr_t high = low + length - 1;
+			addr_t high = addr_dist(rnd);
+			if(low > high) std::swap(low, high);
+			if((rnd() & 7) == 0) {
+				log_debug("clear %.2x to %.2x\n", (int)low, (int)high);
+				clear_range(low, high + 1);
+			} else {
+				log_debug("insert %.2x to %.2x\n", (int)low, (int)high);
+				RTLIL::Const values;
+				for(addr_t addr = low; addr <= high; addr++) {
+					RTLIL::Const word(data_dist(rnd), data_width);
+					values.bits.insert(values.bits.end(), word.bits.begin(), word.bits.end());
+				}
+				insert_concatenated(low, values);
+			}
+		}
+	}
+
+};
+
 struct FunctionalTestGeneric : public Pass
 {
 	FunctionalTestGeneric() : Pass("test_generic", "test the generic compute graph") {}
@@ -40,6 +130,14 @@ struct FunctionalTestGeneric : public Pass
 		size_t argidx = 1;
 		extra_args(args, argidx, design);
 
+		MemContentsTest test(8, 16);
+
+		std::random_device seed_dev;
+		std::mt19937 rnd(23); //seed_dev());
+		test.run(rnd, 1000);
+
+/*
+
 		for (auto module : design->selected_modules()) {
             log("Dumping module `%s'.\n", module->name.c_str());
 			auto fir = FunctionalIR::from_module(module);
@@ -50,6 +148,7 @@ struct FunctionalTestGeneric : public Pass
 			for(auto [name, sort] : fir.state())
 				std::cout << RTLIL::unescape_id(name) << " = " << RTLIL::unescape_id(fir.get_state_next_node(name).name()) << "\n";
 		}
+*/
 	}
 } FunctionalCxxBackend;
 

kernel/functionalir.cc

@@ -19,6 +19,8 @@
 
 #include "kernel/functionalir.h"
 #include <optional>
+#include "ff.h"
+#include "ffinit.h"
 
 YOSYS_NAMESPACE_BEGIN
 
@@ -70,7 +72,7 @@ struct PrintVisitor : FunctionalIR::DefaultVisitor<std::string> {
 	std::string slice(Node, Node a, int offset, int out_width) override { return "slice(" + np(a) + ", " + std::to_string(offset) + ", " + std::to_string(out_width) + ")"; }
 	std::string zero_extend(Node, Node a, int out_width) override { return "zero_extend(" + np(a) + ", " + std::to_string(out_width) + ")"; }
 	std::string sign_extend(Node, Node a, int out_width) override { return "sign_extend(" + np(a) + ", " + std::to_string(out_width) + ")"; }
-	std::string constant(Node, RTLIL::Const value) override { return "constant(" + value.as_string() + ")"; }
+	std::string constant(Node, RTLIL::Const const& value) override { return "constant(" + value.as_string() + ")"; }
 	std::string input(Node, IdString name) override { return "input(" + name.str() + ")"; }
 	std::string state(Node, IdString name) override { return "state(" + name.str() + ")"; }
 	std::string default_handler(Node self) override {
@@ -407,6 +409,8 @@ class FunctionalIRConstruction {
 	CellSimplifier simplifier;
 	vector<Mem> memories_vector;
 	dict<Cell*, Mem*> memories;
+	SigMap sig_map; // TODO: this is only for FfInitVals, remove this once FfInitVals supports DriverMap
+	FfInitVals ff_initvals;
 
 	Node enqueue(DriveSpec const &spec)
 	{
@@ -438,8 +442,11 @@ class FunctionalIRConstruction {
 			return it->second;
 	}
 public:
-	FunctionalIRConstruction(FunctionalIR::Factory &f) : factory(f), simplifier(f) {}
+	FunctionalIRConstruction(Module *module, FunctionalIR::Factory &f)
-	void add_module(Module *module)
+		: factory(f)
+		, simplifier(f)
+		, sig_map(module)
+		, ff_initvals(&sig_map, module)
 	{
 		driver_map.add(module);
 		for (auto cell : module->cells()) {
@@ -447,9 +454,12 @@ public:
 				queue.emplace_back(cell);
 		}
 		for (auto wire : module->wires()) {
+			if (wire->port_input)
+				factory.add_input(wire->name, wire->width);
 			if (wire->port_output) {
-				Node node = enqueue(DriveChunk(DriveChunkWire(wire, 0, wire->width)));
+				factory.add_output(wire->name, wire->width);
-				factory.declare_output(node, wire->name, wire->width);
+				Node value = enqueue(DriveChunk(DriveChunkWire(wire, 0, wire->width)));
+				factory.set_output(wire->name, value);
 			}
 		}
 		memories_vector = Mem::get_all_memories(module);
@@ -487,9 +497,9 @@ public:
 		// - Since wr port j can only have priority over wr port i if j > i, if we do writes in
 		//   ascending index order the result will obey the priorty relation.
 		vector<Node> read_results;
-		int addr_width = ceil_log2(mem->size);
+		factory.add_state(mem->cell->name, FunctionalIR::Sort(ceil_log2(mem->size), mem->width));
-		int data_width = mem->width;
+		factory.set_initial_state(mem->cell->name, MemContents(mem));
-		Node node = factory.state_memory(mem->cell->name, addr_width, data_width);
+		Node node = factory.get_current_state(mem->cell->name);
 		for (size_t i = 0; i < mem->wr_ports.size(); i++) {
 			const auto &wr = mem->wr_ports[i];
 			if (wr.clk_enable)
@@ -513,7 +523,7 @@ public:
 			Node addr = enqueue(driver_map(DriveSpec(rd.addr)));
 			read_results.push_back(factory.memory_read(node, addr));
 		}
-		factory.declare_state_memory(node, mem->cell->name, addr_width, data_width);
+		factory.set_next_state(mem->cell->name, node);
 		return concatenate_read_results(mem, read_results);
 	}
 	void process_cell(Cell *cell)
@@ -527,6 +537,17 @@ public:
 			}
 			Node node = handle_memory(mem);
 			factory.update_pending(cell_outputs.at({cell, ID(RD_DATA)}), node);
+		} else if (RTLIL::builtin_ff_cell_types().count(cell->type)) {
+			FfData ff(&ff_initvals, cell);
+			if (!ff.has_gclk)
+				log_error("The design contains a %s flip-flop at %s. This is not supported by the functional backend. "
+					"Call async2sync or clk2fflogic to avoid this error.\n", log_id(cell->type), log_id(cell));
+			factory.add_state(ff.name, FunctionalIR::Sort(ff.width));
+			Node q_value = factory.get_current_state(ff.name);
+			factory.suggest_name(q_value, ff.name);
+			factory.update_pending(cell_outputs.at({cell, ID(Q)}), q_value);
+			factory.set_next_state(ff.name, enqueue(ff.sig_d));
+			factory.set_initial_state(ff.name, ff.val_init);
 		} else {
 			dict<IdString, Node> connections;
 			IdString output_name; // for the single output case
@@ -572,7 +593,7 @@ public:
 					DriveChunkWire wire_chunk = chunk.wire();
 					if (wire_chunk.is_whole()) {
 						if (wire_chunk.wire->port_input) {
-							Node node = factory.input(wire_chunk.wire->name, wire_chunk.width);
+							Node node = factory.get_input(wire_chunk.wire->name);
 							factory.suggest_name(node, wire_chunk.wire->name);
 							factory.update_pending(pending, node);
 						} else {
@@ -590,24 +611,8 @@ public:
 					DriveChunkPort port_chunk = chunk.port();
 					if (port_chunk.is_whole()) {
 						if (driver_map.celltypes.cell_output(port_chunk.cell->type, port_chunk.port)) {
-							if (port_chunk.cell->type.in(ID($dff), ID($ff)))
-							{
-								Cell *cell = port_chunk.cell;
-								Node node = factory.state(cell->name, port_chunk.width);
-								factory.suggest_name(node, port_chunk.cell->name);
-								factory.update_pending(pending, node);
-								for (auto const &conn : cell->connections()) {
-									if (driver_map.celltypes.cell_input(cell->type, conn.first)) {
-										Node node = enqueue(DriveChunkPort(cell, conn));
-										factory.declare_state(node, cell->name, port_chunk.width);
-									}
-								}
-							}
-							else
-							{
 							Node node = enqueue_cell(port_chunk.cell, port_chunk.port);
 							factory.update_pending(pending, node);
-							}
 						} else {
 							DriveSpec driver = driver_map(DriveSpec(port_chunk));
 							factory.update_pending(pending, enqueue(driver));
@@ -641,8 +646,7 @@ public:
 FunctionalIR FunctionalIR::from_module(Module *module) {
     FunctionalIR ir;
     auto factory = ir.factory();
-    FunctionalIRConstruction ctor(factory);
+    FunctionalIRConstruction ctor(module, factory);
-    ctor.add_module(module);
     ctor.process_queue();
     ir.topological_sort();
     ir.forward_buf();

kernel/functionalir.h

@@ -189,24 +189,11 @@ private:
 	// the bool is true for next state values
 	using Graph = ComputeGraph<NodeData, Attr, IdString, std::pair<IdString, bool>>;
 	Graph _graph;
-	dict<IdString, Sort> _inputs;
+	dict<IdString, Sort> _input_sorts;
-	dict<IdString, Sort> _outputs;
+	dict<IdString, Sort> _output_sorts;
-	dict<IdString, Sort> _state;
+	dict<IdString, Sort> _state_sorts;
-	void add_input(IdString name, Sort sort) {
+	dict<IdString, RTLIL::Const> _initial_state_signal;
-		auto [it, found] = _inputs.emplace(name, std::move(sort));
+	dict<IdString, MemContents> _initial_state_memory;
-		if(found)
-			log_assert(it->second == sort);
-	}
-	void add_state(IdString name, Sort sort) {
-		auto [it, found] = _state.emplace(name, std::move(sort));
-		if(found)
-			log_assert(it->second == sort);
-	}
-	void add_output(IdString name, Sort sort) {
-		auto [it, found] = _outputs.emplace(name, std::move(sort));
-		if(found)
-			log_assert(it->second == sort);
-	}
 public:
 	class Factory;
 	// Node is an immutable reference to a FunctionalIR node
@@ -306,7 +293,7 @@ public:
 		virtual T logical_shift_right(Node self, Node a, Node b) = 0;
 		virtual T arithmetic_shift_right(Node self, Node a, Node b) = 0;
 		virtual T mux(Node self, Node a, Node b, Node s) = 0;
-		virtual T constant(Node self, RTLIL::Const value) = 0;
+		virtual T constant(Node self, RTLIL::Const const & value) = 0;
 		virtual T input(Node self, IdString name) = 0;
 		virtual T state(Node self, IdString name) = 0;
 		virtual T memory_read(Node self, Node mem, Node addr) = 0;
@@ -343,7 +330,7 @@ public:
 		T logical_shift_right(Node self, Node, Node) override { return default_handler(self); }
 		T arithmetic_shift_right(Node self, Node, Node) override { return default_handler(self); }
 		T mux(Node self, Node, Node, Node) override { return default_handler(self); }
-		T constant(Node self, RTLIL::Const) override { return default_handler(self); }
+		T constant(Node self, RTLIL::Const const &) override { return default_handler(self); }
 		T input(Node self, IdString) override { return default_handler(self); }
 		T state(Node self, IdString) override { return default_handler(self); }
 		T memory_read(Node self, Node, Node) override { return default_handler(self); }
@@ -453,29 +440,40 @@ public:
 			log_assert(node.sort() == value.sort());
 			mutate(node).append_arg(value._ref);
 		}
-		Node input(IdString name, int width) {
+		void add_input(IdString name, int width) {
-			_ir.add_input(name, Sort(width));
+			auto [it, inserted] = _ir._input_sorts.emplace(name, Sort(width));
-			return add(NodeData(Fn::input, name), Sort(width), {});
+			if (!inserted) log_error("input `%s` was re-defined", name.c_str());
 		}
-		Node state(IdString name, int width) {
+		void add_output(IdString name, int width) {
-			_ir.add_state(name, Sort(width));
+			auto [it, inserted] = _ir._output_sorts.emplace(name, Sort(width));
-			return add(NodeData(Fn::state, name), Sort(width), {});
+			if (!inserted) log_error("output `%s` was re-defined", name.c_str());
 		}
-		Node state_memory(IdString name, int addr_width, int data_width) {
+		void add_state(IdString name, Sort sort) {
-			_ir.add_state(name, Sort(addr_width, data_width));
+			auto [it, inserted] = _ir._state_sorts.emplace(name, sort);
-			return add(NodeData(Fn::state, name), Sort(addr_width, data_width), {});
+			if (!inserted) log_error("state `%s` was re-defined", name.c_str());
 		}
-		void declare_output(Node node, IdString name, int width) {
+		Node get_input(IdString name) {
-			_ir.add_output(name, Sort(width));
+			return add(NodeData(Fn::input, name), Sort(_ir._input_sorts.at(name)), {});
-			mutate(node).assign_key({name, false});
 		}
-		void declare_state(Node node, IdString name, int width) {
+		Node get_current_state(IdString name) {
-			_ir.add_state(name, Sort(width));
+			return add(NodeData(Fn::state, name), Sort(_ir._state_sorts.at(name)), {});
-			mutate(node).assign_key({name, true});
 		}
-		void declare_state_memory(Node node, IdString name, int addr_width, int data_width) {
+		void set_output(IdString output, Node value) {
-			_ir.add_state(name, Sort(addr_width, data_width));
+			log_assert(_ir._output_sorts.at(output) == value.sort());
-			mutate(node).assign_key({name, true});
+			mutate(value).assign_key({output, false});
+		}
+		void set_initial_state(IdString state, RTLIL::Const value) {
+			Sort &sort = _ir._state_sorts.at(state);
+			value.extu(sort.width());
+			_ir._initial_state_signal.emplace(state, std::move(value));
+		}
+		void set_initial_state(IdString state, MemContents value) {
+			log_assert(Sort(value.addr_width(), value.data_width()) == _ir._state_sorts.at(state));
+			_ir._initial_state_memory.emplace(state, std::move(value));
+		}
+		void set_next_state(IdString state, Node value) {
+			log_assert(_ir._state_sorts.at(state) == value.sort());
+			mutate(value).assign_key({state, true});
 		}
 		void suggest_name(Node node, IdString name) {
 			mutate(node).sparse_attr() = name;
@@ -487,9 +485,11 @@ public:
 	Node operator[](int i) { return Node(_graph[i]); }
 	void topological_sort();
 	void forward_buf();
-	dict<IdString, Sort> inputs() const { return _inputs; }
+	dict<IdString, Sort> inputs() const { return _input_sorts; }
-	dict<IdString, Sort> outputs() const { return _outputs; }
+	dict<IdString, Sort> outputs() const { return _output_sorts; }
-	dict<IdString, Sort> state() const { return _state; }
+	dict<IdString, Sort> state() const { return _state_sorts; }
+	RTLIL::Const  const &get_initial_state_signal(IdString name) { return _initial_state_signal.at(name); }
+	MemContents const &get_initial_state_memory(IdString name) { return _initial_state_memory.at(name); }
 	Node get_output_node(IdString name) { return Node(_graph({name, false})); }
 	Node get_state_next_node(IdString name) { return Node(_graph({name, true})); }
 	class Iterator {

tests/functional/rtlil_cells.py

@@ -153,15 +153,17 @@ class FFCell(BaseCell):
         from test_functional import yosys_synth
         verilog_file = path.parent / 'verilog.v'
         with open(verilog_file, 'w') as f:
-            f.write("""
+            width = parameters['WIDTH']
+            f.write(f"""
 module gold(
     input wire clk,
-    input wire [{0}:0] D,
+    input wire [{width-1}:0] D,
-    output reg [{0}:0] Q
+    output reg [{width-1}:0] Q
 );
+    initial Q = {width}'b{("101" * width)[:width]};
     always @(posedge clk)
         Q <= D;
-endmodule""".format(parameters['WIDTH'] - 1))
+endmodule""")
         yosys_synth(verilog_file, path)
 
 class MemCell(BaseCell):
@@ -180,6 +182,10 @@ module gold(
     output reg [{0}:0] RD
 );
     reg [{0}:0] mem[0:{2}];
+    integer i;
+    initial
+        for(i = 0; i <= {2}; i = i + 1)
+            mem[i] = 9192 * (i + 1);
     always @(*)
         RD = mem[RA];
     always @(posedge clk)
@@ -211,8 +217,11 @@ module gold(
     output reg [{0}:0] RD1,
     output reg [{0}:0] RD2
 );
-                    (*keep*)
     reg [{0}:0] mem[0:{2}];
+    integer i;
+    initial
+        for(i = 0; i <= {2}; i = i + 1)
+            mem[i] = 9192 * (i + 1);
     always @(*)
         RD1 = mem[RA1];
     always @(*)

tests/functional/smt_vcd.py

@@ -81,25 +81,6 @@ def simulate_smt_with_smtio(smt_file_path, vcd_path, smt_io, num_steps, rnd):
     parser.finish()
     assert smt_io.check_sat() == 'sat'
 
-    def initial_state(states):
-        mk_state_parts = []
-        rv = []
-        for name, width in states.items():
-            if isinstance(width, int):
-                binary_string = format(0, '0{}b'.format(width))
-                mk_state_parts.append(f"#b{binary_string}")
-            else:
-                binary_string = format(0, '0{}b'.format(width[1]))
-                rv.append(f"(declare-const test_state_initial_mem_{name} (Array (_ BitVec {width[0]}) (_ BitVec {width[1]})))")
-                rv.append(f"(assert (forall ((i (_ BitVec {width[0]}))) (= (select test_state_initial_mem_{name} i) #b{binary_string})))")
-                mk_state_parts.append(f"test_state_initial_mem_{name}")
-        if len(states) == 0:
-            mk_state_call = "gold_State"
-        else:
-            mk_state_call = "(gold_State {})".format(" ".join(mk_state_parts))
-        rv.append(f"(define-const test_state_step_n0 gold_State {mk_state_call})\n")
-        return rv
-
     def set_step(inputs, step):
         # This function assumes 'inputs' is a dictionary like {"A": 5, "B": 4}
         # and 'input_values' is a dictionary like {"A": 5, "B": 13} specifying the concrete values for each input.
@@ -118,7 +99,7 @@ def simulate_smt_with_smtio(smt_file_path, vcd_path, smt_io, num_steps, rnd):
             f"(define-const test_state_step_n{step+1} gold_State (second test_results_step_n{step}))\n",
         ]
 
-    smt_commands = initial_state(states)
+    smt_commands = [f"(define-const test_state_step_n0 gold_State gold-initial)\n"]
     for step in range(num_steps):
         for step_command in set_step(inputs, step):
             smt_commands.append(step_command)

tests/functional/test_functional.py

@@ -29,14 +29,14 @@ def yosys_synth(verilog_file, rtlil_file):
 # simulate an rtlil file with yosys, comparing with a given vcd file, and writing out the yosys simulation results into a second vcd file
 def yosys_sim(rtlil_file, vcd_reference_file, vcd_out_file, preprocessing = ""):
     try:
-        yosys(f"read_rtlil {quote(rtlil_file)}; {preprocessing}; sim -r {quote(vcd_reference_file)} -scope gold -vcd {quote(vcd_out_file)} -timescale 1us -sim-gold")
+        yosys(f"read_rtlil {quote(rtlil_file)}; {preprocessing}; sim -r {quote(vcd_reference_file)} -scope gold -vcd {quote(vcd_out_file)} -timescale 1us -sim-gold -fst-noinit")
     except:
         # if yosys sim fails it's probably because of a simulation mismatch
         # since yosys sim aborts on simulation mismatch to generate vcd output
         # we have to re-run with a different set of flags
         # on this run we ignore output and return code, we just want a best-effort attempt to get a vcd
         subprocess.run([base_path / 'yosys', '-Q', '-p',
-            f'read_rtlil {quote(rtlil_file)}; sim -vcd {quote(vcd_out_file)} -a -r {quote(vcd_reference_file)} -scope gold -timescale 1us'],
+            f'read_rtlil {quote(rtlil_file)}; sim -vcd {quote(vcd_out_file)} -a -r {quote(vcd_reference_file)} -scope gold -timescale 1us -fst-noinit'],
             capture_output=True, check=False)
         raise
 

tests/functional/vcd_harness.cc

@@ -7,7 +7,11 @@
 
 #include "my_module_functional_cxx.cc"
 
-std::string vcd_name_mangle(std::string name) {
+class VcdFile {
+	std::ofstream &ofs;
+	std::string code_alloc = "!";
+	std::unordered_map<std::string, std::string> codes;
+	std::string name_mangle(std::string name) {
 		std::string ret = name;
 		bool escape = ret.empty() || !isalpha(ret[0]) && ret[0] != '_';
 		for(size_t i = 0; i < ret.size(); i++) {
@@ -20,55 +24,76 @@ std::string vcd_name_mangle(std::string name) {
 		else
 			return ret;
 	}
-std::unordered_map<std::string, std::string> codes; 
+	std::string allocate_code() {
-
+		std::string ret = code_alloc;
-struct DumpHeader {
+		for (size_t i = 0; i < code_alloc.size(); i++)
-  std::ofstream &ofs;
+			if (code_alloc[i]++ == '~')
-  std::string code = "!";
+				code_alloc[i] = '!';
-  DumpHeader(std::ofstream &ofs) : ofs(ofs) {}
-  void increment_code() {
-    for(size_t i = 0; i < code.size(); i++)
-      if(code[i]++ == '~')
-        code[i] = '!';
 			else
-        return;
+				return ret;
-    code.push_back('!');
+		code_alloc.push_back('!');
+		return ret;
 	}
-  template <size_t n>
+public:
-  void operator()(const char *name, Signal<n> value) {
+	VcdFile(std::ofstream &ofs) : ofs(ofs) {}
-    ofs << "$var wire " << n << " " << code << " " << vcd_name_mangle(name) << " $end\n";
+	struct DumpHeader {
-    codes[name] = code;
+		VcdFile *file;
-    increment_code();
+		explicit DumpHeader(VcdFile *file) : file(file) {}
-  }
+		template <size_t n> void operator()(const char *name, Signal<n> value)
-  template <size_t n, size_t m>
+		{
-  void operator()(const char *name, Memory<n, m> value) {
+			auto it = file->codes.find(name);
+			if(it == file->codes.end())
+				it = file->codes.emplace(name, file->allocate_code()).first;
+			file->ofs << "$var wire " << n << " " << it->second << " " << file->name_mangle(name) << " $end\n";
 		}
+		template <size_t n, size_t m> void operator()(const char *name, Memory<n, m> value) {}
 	};
-
 	struct Dump {
-  std::ofstream &ofs;
+		VcdFile *file;
-  Dump(std::ofstream &ofs) : ofs(ofs) {}
+		explicit Dump(VcdFile *file) : file(file) {}
-  template <size_t n>
+		template <size_t n> void operator()(const char *name, Signal<n> value)
-  void operator()(const char *name, Signal<n> value) {
+		{
-    // Bit
 			if (n == 1) {
-      ofs << (value[0] ? '1' : '0');
+				file->ofs << (value[0] ? '1' : '0');
-      ofs << codes[name] << "\n";
+				file->ofs << file->codes.at(name) << "\n";
-      return;
+			} else {
-    }
+				file->ofs << "b";
-    // vector (multi-bit) signals
-    ofs << "b";
 				for (size_t i = n; i-- > 0;)
-      ofs << (value[i] ? '1' : '0');
+					file->ofs << (value[i] ? '1' : '0');
-    ofs << " " << codes[name] << "\n";
+				file->ofs << " " << file->codes.at(name) << "\n";
 			}
-  template <size_t n, size_t m>
-  void operator()(const char *name, Memory<n, m> value) {
 		}
+		template <size_t n, size_t m> void operator()(const char *name, Memory<n, m> value) {}
+	};
+	void begin_header() {
+		constexpr int number_timescale = 1;
+		const std::string units_timescale = "us";
+		ofs << "$timescale " << number_timescale << " " << units_timescale << " $end\n";
+		ofs << "$scope module gold $end\n";
+	}
+	void end_header() {
+		ofs << "$enddefinitions $end\n$dumpvars\n";
+	}
+	template<typename... Args> void header(Args ...args) {
+		begin_header();
+		DumpHeader d(this);
+		(args.visit(d), ...);
+		end_header();
+	}
+	void begin_data(int step) {
+		ofs << "#" << step << "\n";
+	}
+	template<typename... Args> void data(int step, Args ...args) {
+		begin_data(step);
+		Dump d(this);
+		(args.visit(d), ...);
+	}
+	DumpHeader dump_header() { return DumpHeader(this); }
+	Dump dump() { return Dump(this); }
 };
 
-template<size_t n>
+template <size_t n> Signal<n> random_signal(std::mt19937 &gen)
-Signal<n> random_signal(std::mt19937 &gen) {
+{
 	std::uniform_int_distribution<uint32_t> dist;
 	std::array<uint32_t, (n + 31) / 32> words;
 	for (auto &w : words)
@@ -76,21 +101,11 @@ Signal<n> random_signal(std::mt19937 &gen) {
 	return Signal<n>::from_array(words);
 }
 
-struct Reset {
-  template <size_t n>
-  void operator()(const char *, Signal<n> &signal) {
-    signal = 0;
-  }
-};
-
 struct Randomize {
 	std::mt19937 &gen;
 	Randomize(std::mt19937 &gen) : gen(gen) {}
 
-  template <size_t n>
+	template <size_t n> void operator()(const char *, Signal<n> &signal) { signal = random_signal<n>(gen); }
-  void operator()(const char *, Signal<n> &signal) {
-    signal = random_signal<n>(gen);
-  }
 };
 
 int main(int argc, char **argv)
@@ -104,43 +119,27 @@ int main(int argc, char **argv)
 	const int steps = atoi(argv[2]);
 	const uint32_t seed = atoi(argv[3]);
 
-  constexpr int number_timescale = 1;
-  const std::string units_timescale = "us";
 	gold::Inputs inputs;
 	gold::Outputs outputs;
 	gold::State state;
 	gold::State next_state;
 
 	std::ofstream vcd_file(functional_vcd_filename);
+	VcdFile vcd(vcd_file);
+	vcd.header(inputs, outputs, state);
 
-  vcd_file << "$timescale " << number_timescale << " " << units_timescale << " $end\n";
-  vcd_file << "$scope module gold $end\n";
-  {
-    DumpHeader d(vcd_file);
-    inputs.visit(d);
-    outputs.visit(d);
-    state.visit(d);
-  }
-  vcd_file << "$enddefinitions $end\n$dumpvars\n";
 	std::mt19937 gen(seed);
 
-  inputs.visit(Reset());
+	gold::initialize(state);
 
 	for (int step = 0; step < steps; ++step) {
-    vcd_file << "#" << step << "\n";
+		inputs.visit(Randomize(gen));
+
 		gold::eval(inputs, outputs, state, next_state);
-    {
+		vcd.data(step, inputs, outputs, state);
-      Dump d(vcd_file);
-      inputs.visit(d);
-      outputs.visit(d);
-      state.visit(d);
-    }
 
 		state = next_state;
-    inputs.visit(Randomize(gen));
 	}
 
-  vcd_file.close();
-
 	return 0;
 }