cxxrtl: rename cxxrtl.cc→cxxrtl_backend.cc.

To avoid confusion with the C++ source files that are a part of
the simulation itself and not a part of Yosys build.

1 files changed, 0 insertions, 2520 deletions

diff --git a/backends/cxxrtl/cxxrtl.cc b/backends/cxxrtl/cxxrtl.cc
deleted file mode 100644
index 64af5dab8..000000000
--- a/backends/cxxrtl/cxxrtl.cc
+++ /dev/null
@@ -1,2520 +0,0 @@
-/*
- *  yosys -- Yosys Open SYnthesis Suite
- *
- *  Copyright (C) 2019-2020  whitequark <whitequark@whitequark.org>
- *
- *  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/rtlil.h"
-#include "kernel/register.h"
-#include "kernel/sigtools.h"
-#include "kernel/utils.h"
-#include "kernel/celltypes.h"
-#include "kernel/log.h"
-
-USING_YOSYS_NAMESPACE
-PRIVATE_NAMESPACE_BEGIN
-
-// [[CITE]]
-// Peter Eades; Xuemin Lin; W. F. Smyth, "A Fast Effective Heuristic For The Feedback Arc Set Problem"
-// Information Processing Letters, Vol. 47, pp 319-323, 1993
-// https://pdfs.semanticscholar.org/c7ed/d9acce96ca357876540e19664eb9d976637f.pdf
-
-// A topological sort (on a cell/wire graph) is always possible in a fully flattened RTLIL design without
-// processes or logic loops where every wire has a single driver. Logic loops are illegal in RTLIL and wires
-// with multiple drivers can be split by the `splitnets` pass; however, interdependencies between processes
-// or module instances can create strongly connected components without introducing evaluation nondeterminism.
-// We wish to support designs with such benign SCCs (as well as designs with multiple drivers per wire), so
-// we sort the graph in a way that minimizes feedback arcs. If there are no feedback arcs in the sorted graph,
-// then a more efficient evaluation method is possible, since eval() will always immediately converge.
-template<class T>
-struct Scheduler {
-	struct Vertex {
-		T *data;
-		Vertex *prev, *next;
-		pool<Vertex*, hash_ptr_ops> preds, succs;
-
-		Vertex() : data(NULL), prev(this), next(this) {}
-		Vertex(T *data) : data(data), prev(NULL), next(NULL) {}
-
-		bool empty() const
-		{
-			log_assert(data == NULL);
-			if (next == this) {
-				log_assert(prev == next);
-				return true;
-			}
-			return false;
-		}
-
-		void link(Vertex *list)
-		{
-			log_assert(prev == NULL && next == NULL);
-			next = list;
-			prev = list->prev;
-			list->prev->next = this;
-			list->prev = this;
-		}
-
-		void unlink()
-		{
-			log_assert(prev->next == this && next->prev == this);
-			prev->next = next;
-			next->prev = prev;
-			next = prev = NULL;
-		}
-
-		int delta() const
-		{
-			return succs.size() - preds.size();
-		}
-	};
-
-	std::vector<Vertex*> vertices;
-	Vertex *sources = new Vertex;
-	Vertex *sinks = new Vertex;
-	dict<int, Vertex*> bins;
-
-	~Scheduler()
-	{
-		delete sources;
-		delete sinks;
-		for (auto bin : bins)
-			delete bin.second;
-		for (auto vertex : vertices)
-			delete vertex;
-	}
-
-	Vertex *add(T *data)
-	{
-		Vertex *vertex = new Vertex(data);
-		vertices.push_back(vertex);
-		return vertex;
-	}
-
-	void relink(Vertex *vertex)
-	{
-		if (vertex->succs.empty())
-			vertex->link(sinks);
-		else if (vertex->preds.empty())
-			vertex->link(sources);
-		else {
-			int delta = vertex->delta();
-			if (!bins.count(delta))
-				bins[delta] = new Vertex;
-			vertex->link(bins[delta]);
-		}
-	}
-
-	Vertex *remove(Vertex *vertex)
-	{
-		vertex->unlink();
-		for (auto pred : vertex->preds) {
-			if (pred == vertex)
-				continue;
-			log_assert(pred->succs[vertex]);
-			pred->unlink();
-			pred->succs.erase(vertex);
-			relink(pred);
-		}
-		for (auto succ : vertex->succs) {
-			if (succ == vertex)
-				continue;
-			log_assert(succ->preds[vertex]);
-			succ->unlink();
-			succ->preds.erase(vertex);
-			relink(succ);
-		}
-		vertex->preds.clear();
-		vertex->succs.clear();
-		return vertex;
-	}
-
-	std::vector<Vertex*> schedule()
-	{
-		std::vector<Vertex*> s1, s2r;
-		for (auto vertex : vertices)
-			relink(vertex);
-		bool bins_empty = false;
-		while (!(sinks->empty() && sources->empty() && bins_empty)) {
-			while (!sinks->empty())
-				s2r.push_back(remove(sinks->next));
-			while (!sources->empty())
-				s1.push_back(remove(sources->next));
-			// Choosing u in this implementation isn't O(1), but the paper handwaves which data structure they suggest
-			// using to get O(1) relinking *and* find-max-key ("it is clear"... no it isn't), so this code uses a very
-			// naive implementation of find-max-key.
-			bins_empty = true;
-			bins.template sort<std::greater<int>>();
-			for (auto bin : bins) {
-				if (!bin.second->empty()) {
-					bins_empty = false;
-					s1.push_back(remove(bin.second->next));
-					break;
-				}
-			}
-		}
-		s1.insert(s1.end(), s2r.rbegin(), s2r.rend());
-		return s1;
-	}
-};
-
-bool is_input_wire(const RTLIL::Wire *wire)
-{
-	return wire->port_input && !wire->port_output;
-}
-
-bool is_unary_cell(RTLIL::IdString type)
-{
-	return type.in(
-		ID($not), ID($logic_not), ID($reduce_and), ID($reduce_or), ID($reduce_xor), ID($reduce_xnor), ID($reduce_bool),
-		ID($pos), ID($neg));
-}
-
-bool is_binary_cell(RTLIL::IdString type)
-{
-	return type.in(
-		ID($and), ID($or), ID($xor), ID($xnor), ID($logic_and), ID($logic_or),
-		ID($shl), ID($sshl), ID($shr), ID($sshr), ID($shift), ID($shiftx),
-		ID($eq), ID($ne), ID($eqx), ID($nex), ID($gt), ID($ge), ID($lt), ID($le),
-		ID($add), ID($sub), ID($mul), ID($div), ID($mod));
-}
-
-bool is_elidable_cell(RTLIL::IdString type)
-{
-	return is_unary_cell(type) || is_binary_cell(type) || type.in(
-		ID($mux), ID($concat), ID($slice));
-}
-
-bool is_sync_ff_cell(RTLIL::IdString type)
-{
-	return type.in(
-		ID($dff), ID($dffe));
-}
-
-bool is_ff_cell(RTLIL::IdString type)
-{
-	return is_sync_ff_cell(type) || type.in(
-		ID($adff), ID($dffsr), ID($dlatch), ID($dlatchsr), ID($sr));
-}
-
-bool is_internal_cell(RTLIL::IdString type)
-{
-	return type[0] == '$' && !type.begins_with("$paramod");
-}
-
-bool is_cxxrtl_blackbox_cell(const RTLIL::Cell *cell)
-{
-	RTLIL::Module *cell_module = cell->module->design->module(cell->type);
-	log_assert(cell_module != nullptr);
-	return cell_module->get_bool_attribute(ID(cxxrtl_blackbox));
-}
-
-enum class CxxrtlPortType {
-	UNKNOWN = 0, // or mixed comb/sync
-	COMB = 1,
-	SYNC = 2,
-};
-
-CxxrtlPortType cxxrtl_port_type(const RTLIL::Cell *cell, RTLIL::IdString port)
-{
-	RTLIL::Module *cell_module = cell->module->design->module(cell->type);
-	if (cell_module == nullptr || !cell_module->get_bool_attribute(ID(cxxrtl_blackbox)))
-		return CxxrtlPortType::UNKNOWN;
-	RTLIL::Wire *cell_output_wire = cell_module->wire(port);
-	log_assert(cell_output_wire != nullptr);
-	bool is_comb = cell_output_wire->get_bool_attribute(ID(cxxrtl_comb));
-	bool is_sync = cell_output_wire->get_bool_attribute(ID(cxxrtl_sync));
-	if (is_comb && is_sync)
-		log_cmd_error("Port `%s.%s' is marked as both `cxxrtl_comb` and `cxxrtl_sync`.\n",
-		              log_id(cell_module), log_signal(cell_output_wire));
-	else if (is_comb)
-		return CxxrtlPortType::COMB;
-	else if (is_sync)
-		return CxxrtlPortType::SYNC;
-	return CxxrtlPortType::UNKNOWN;
-}
-
-bool is_cxxrtl_comb_port(const RTLIL::Cell *cell, RTLIL::IdString port)
-{
-	return cxxrtl_port_type(cell, port) == CxxrtlPortType::COMB;
-}
-
-bool is_cxxrtl_sync_port(const RTLIL::Cell *cell, RTLIL::IdString port)
-{
-	return cxxrtl_port_type(cell, port) == CxxrtlPortType::SYNC;
-}
-
-struct FlowGraph {
-	struct Node {
-		enum class Type {
-			CONNECT,
-			CELL_SYNC,
-			CELL_EVAL,
-			PROCESS
-		};
-
-		Type type;
-		RTLIL::SigSig connect = {};
-		const RTLIL::Cell *cell = NULL;
-		const RTLIL::Process *process = NULL;
-	};
-
-	std::vector<Node*> nodes;
-	dict<const RTLIL::Wire*, pool<Node*, hash_ptr_ops>> wire_comb_defs, wire_sync_defs, wire_uses;
-	dict<const RTLIL::Wire*, bool> wire_def_elidable, wire_use_elidable;
-
-	~FlowGraph()
-	{
-		for (auto node : nodes)
-			delete node;
-	}
-
-	void add_defs(Node *node, const RTLIL::SigSpec &sig, bool fully_sync, bool elidable)
-	{
-		for (auto chunk : sig.chunks())
-			if (chunk.wire) {
-				if (fully_sync)
-					wire_sync_defs[chunk.wire].insert(node);
-				else
-					wire_comb_defs[chunk.wire].insert(node);
-			}
-		// Only comb defs of an entire wire in the right order can be elided.
-		if (!fully_sync && sig.is_wire())
-			wire_def_elidable[sig.as_wire()] = elidable;
-	}
-
-	void add_uses(Node *node, const RTLIL::SigSpec &sig)
-	{
-		for (auto chunk : sig.chunks())
-			if (chunk.wire) {
-				wire_uses[chunk.wire].insert(node);
-				// Only a single use of an entire wire in the right order can be elided.
-				// (But the use can include other chunks.)
-				if (!wire_use_elidable.count(chunk.wire))
-					wire_use_elidable[chunk.wire] = true;
-				else
-					wire_use_elidable[chunk.wire] = false;
-			}
-	}
-
-	bool is_elidable(const RTLIL::Wire *wire) const
-	{
-		if (wire_def_elidable.count(wire) && wire_use_elidable.count(wire))
-			return wire_def_elidable.at(wire) && wire_use_elidable.at(wire);
-		return false;
-	}
-
-	// Connections
-	void add_connect_defs_uses(Node *node, const RTLIL::SigSig &conn)
-	{
-		add_defs(node, conn.first, /*fully_sync=*/false, /*elidable=*/true);
-		add_uses(node, conn.second);
-	}
-
-	Node *add_node(const RTLIL::SigSig &conn)
-	{
-		Node *node = new Node;
-		node->type = Node::Type::CONNECT;
-		node->connect = conn;
-		nodes.push_back(node);
-		add_connect_defs_uses(node, conn);
-		return node;
-	}
-
-	// Cells
-	void add_cell_sync_defs(Node *node, const RTLIL::Cell *cell)
-	{
-		// To understand why this node type is necessary and why it produces comb defs, consider a cell
-		// with input \i and sync output \o, used in a design such that \i is connected to \o. This does
-		// not result in a feedback arc because the output is synchronous. However, a naive implementation
-		// of code generation for cells that assigns to inputs, evaluates cells, assigns from outputs
-		// would not be able to immediately converge...
-		//
-		//   wire<1> i_tmp;
-		//   cell->p_i = i_tmp.curr;
-		//   cell->eval();
-		//   i_tmp.next = cell->p_o.curr;
-		//
-		// ... since the wire connecting the input and output ports would not be localizable. To solve
-		// this, the cell is split into two scheduling nodes; one exclusively for sync outputs, and
-		// another for inputs and all non-sync outputs. This way the generated code can be rearranged...
-		//
-		//   value<1> i_tmp;
-		//   i_tmp = cell->p_o.curr;
-		//   cell->p_i = i_tmp;
-		//   cell->eval();
-		//
-		// eliminating the unnecessary delta cycle. Conceptually, the CELL_SYNC node type is a series of
-		// connections of the form `connect \lhs \cell.\sync_output`; the right-hand side of these is not
-		// as a wire in RTLIL. If it was expressible, then `\cell.\sync_output` would have a sync def,
-		// and this node would be an ordinary CONNECT node, with `\lhs` having a comb def. Because it isn't,
-		// a special node type is used, the right-hand side does not appear anywhere, and the left-hand
-		// side has a comb def.
-		for (auto conn : cell->connections())
-			if (cell->output(conn.first))
-				if (is_cxxrtl_sync_port(cell, conn.first)) {
-					// See note regarding elidability below.
-					add_defs(node, conn.second, /*fully_sync=*/false, /*elidable=*/false);
-				}
-	}
-
-	void add_cell_eval_defs_uses(Node *node, const RTLIL::Cell *cell)
-	{
-		for (auto conn : cell->connections()) {
-			if (cell->output(conn.first)) {
-				if (is_elidable_cell(cell->type))
-					add_defs(node, conn.second, /*fully_sync=*/false, /*elidable=*/true);
-				else if (is_sync_ff_cell(cell->type) || (cell->type == ID($memrd) && cell->getParam(ID::CLK_ENABLE).as_bool()))
-					add_defs(node, conn.second, /*fully_sync=*/true,  /*elidable=*/false);
-				else if (is_internal_cell(cell->type))
-					add_defs(node, conn.second, /*fully_sync=*/false, /*elidable=*/false);
-				else if (!is_cxxrtl_sync_port(cell, conn.first)) {
-					// Although at first it looks like outputs of user-defined cells may always be elided, the reality is
-					// more complex. Fully sync outputs produce no defs and so don't participate in elision. Fully comb
-					// outputs are assigned in a different way depending on whether the cell's eval() immediately converged.
-					// Unknown/mixed outputs could be elided, but should be rare in practical designs and don't justify
-					// the infrastructure required to elide outputs of cells with many of them.
-					add_defs(node, conn.second, /*fully_sync=*/false, /*elidable=*/false);
-				}
-			}
-			if (cell->input(conn.first))
-				add_uses(node, conn.second);
-		}
-	}
-
-	Node *add_node(const RTLIL::Cell *cell)
-	{
-		log_assert(cell->known());
-
-		bool has_fully_sync_outputs = false;
-		for (auto conn : cell->connections())
-			if (cell->output(conn.first) && is_cxxrtl_sync_port(cell, conn.first)) {
-				has_fully_sync_outputs = true;
-				break;
-			}
-		if (has_fully_sync_outputs) {
-			Node *node = new Node;
-			node->type = Node::Type::CELL_SYNC;
-			node->cell = cell;
-			nodes.push_back(node);
-			add_cell_sync_defs(node, cell);
-		}
-
-		Node *node = new Node;
-		node->type = Node::Type::CELL_EVAL;
-		node->cell = cell;
-		nodes.push_back(node);
-		add_cell_eval_defs_uses(node, cell);
-		return node;
-	}
-
-	// Processes
-	void add_case_defs_uses(Node *node, const RTLIL::CaseRule *case_)
-	{
-		for (auto &action : case_->actions) {
-			add_defs(node, action.first, /*is_sync=*/false, /*elidable=*/false);
-			add_uses(node, action.second);
-		}
-		for (auto sub_switch : case_->switches) {
-			add_uses(node, sub_switch->signal);
-			for (auto sub_case : sub_switch->cases) {
-				for (auto &compare : sub_case->compare)
-					add_uses(node, compare);
-				add_case_defs_uses(node, sub_case);
-			}
-		}
-	}
-
-	void add_process_defs_uses(Node *node, const RTLIL::Process *process)
-	{
-		add_case_defs_uses(node, &process->root_case);
-		for (auto sync : process->syncs)
-			for (auto action : sync->actions) {
-				if (sync->type == RTLIL::STp || sync->type == RTLIL::STn || sync->type == RTLIL::STe)
-				  add_defs(node, action.first, /*is_sync=*/true,  /*elidable=*/false);
-				else
-					add_defs(node, action.first, /*is_sync=*/false, /*elidable=*/false);
-				add_uses(node, action.second);
-			}
-	}
-
-	Node *add_node(const RTLIL::Process *process)
-	{
-		Node *node = new Node;
-		node->type = Node::Type::PROCESS;
-		node->process = process;
-		nodes.push_back(node);
-		add_process_defs_uses(node, process);
-		return node;
-	}
-};
-
-std::vector<std::string> split_by(const std::string &str, const std::string &sep)
-{
-	std::vector<std::string> result;
-	size_t prev = 0;
-	while (true) {
-		size_t curr = str.find_first_of(sep, prev + 1);
-		if (curr > str.size())
-			curr = str.size();
-		if (curr > prev + 1)
-			result.push_back(str.substr(prev, curr - prev));
-		if (curr == str.size())
-			break;
-		prev = curr;
-	}
-	return result;
-}
-
-std::string escape_cxx_string(const std::string &input)
-{
-	std::string output = "\"";
-	for (auto c : input) {
-		if (::isprint(c)) {
-			if (c == '\\')
-				output.push_back('\\');
-			output.push_back(c);
-		} else {
-			char l = c & 0xf, h = (c >> 4) & 0xf;
-			output.append("\\x");
-			output.push_back((h < 10 ? '0' + h : 'a' + h - 10));
-			output.push_back((l < 10 ? '0' + l : 'a' + l - 10));
-		}
-	}
-	output.push_back('"');
-	if (output.find('\0') != std::string::npos) {
-		output.insert(0, "std::string {");
-		output.append(stringf(", %zu}", input.size()));
-	}
-	return output;
-}
-
-template<class T>
-std::string get_hdl_name(T *object)
-{
-	if (object->has_attribute(ID::hdlname))
-		return object->get_string_attribute(ID::hdlname);
-	else
-		return object->name.str();
-}
-
-struct CxxrtlWorker {
-	bool split_intf = false;
-	std::string intf_filename;
-	std::string design_ns = "cxxrtl_design";
-	std::ostream *impl_f = nullptr;
-	std::ostream *intf_f = nullptr;
-
-	bool elide_internal = false;
-	bool elide_public = false;
-	bool localize_internal = false;
-	bool localize_public = false;
-	bool run_proc_flatten = false;
-	bool max_opt_level = false;
-
-	bool debug_info = false;
-
-	std::ostringstream f;
-	std::string indent;
-	int temporary = 0;
-
-	dict<const RTLIL::Module*, SigMap> sigmaps;
-	pool<const RTLIL::Wire*> edge_wires;
-	dict<RTLIL::SigBit, RTLIL::SyncType> edge_types;
-	pool<const RTLIL::Memory*> writable_memories;
-	dict<const RTLIL::Cell*, pool<const RTLIL::Cell*>> transparent_for;
-	dict<const RTLIL::Wire*, FlowGraph::Node> elided_wires;
-	dict<const RTLIL::Module*, std::vector<FlowGraph::Node>> schedule;
-	pool<const RTLIL::Wire*> localized_wires;
-	dict<const RTLIL::Module*, pool<std::string>> blackbox_specializations;
-	dict<const RTLIL::Module*, bool> eval_converges;
-
-	void inc_indent() {
-		indent += "\t";
-	}
-	void dec_indent() {
-		indent.resize(indent.size() - 1);
-	}
-
-	// RTLIL allows any characters in names other than whitespace. This presents an issue for generating C++ code
-	// because C++ identifiers may be only alphanumeric, cannot clash with C++ keywords, and cannot clash with cxxrtl
-	// identifiers. This issue can be solved with a name mangling scheme. We choose a name mangling scheme that results
-	// in readable identifiers, does not depend on an up-to-date list of C++ keywords, and is easy to apply. Its rules:
-	//  1. All generated identifiers start with `_`.
-	//  1a. Generated identifiers for public names (beginning with `\`) start with `p_`.
-	//  1b. Generated identifiers for internal names (beginning with `$`) start with `i_`.
-	//  2. An underscore is escaped with another underscore, i.e. `__`.
-	//  3. Any other non-alnum character is escaped with underscores around its lowercase hex code, e.g. `@` as `_40_`.
-	std::string mangle_name(const RTLIL::IdString &name)
-	{
-		std::string mangled;
-		bool first = true;
-		for (char c : name.str()) {
-			if (first) {
-				first = false;
-				if (c == '\\')
-					mangled += "p_";
-				else if (c == '$')
-					mangled += "i_";
-				else
-					log_assert(false);
-			} else {
-				if (isalnum(c)) {
-					mangled += c;
-				} else if (c == '_') {
-					mangled += "__";
-				} else {
-					char l = c & 0xf, h = (c >> 4) & 0xf;
-					mangled += '_';
-					mangled += (h < 10 ? '0' + h : 'a' + h - 10);
-					mangled += (l < 10 ? '0' + l : 'a' + l - 10);
-					mangled += '_';
-				}
-			}
-		}
-		return mangled;
-	}
-
-	std::string mangle_module_name(const RTLIL::IdString &name, bool is_blackbox = false)
-	{
-		// Class namespace.
-		if (is_blackbox)
-			return "bb_" + mangle_name(name);
-		return mangle_name(name);
-	}
-
-	std::string mangle_memory_name(const RTLIL::IdString &name)
-	{
-		// Class member namespace.
-		return "memory_" + mangle_name(name);
-	}
-
-	std::string mangle_cell_name(const RTLIL::IdString &name)
-	{
-		// Class member namespace.
-		return "cell_" + mangle_name(name);
-	}
-
-	std::string mangle_wire_name(const RTLIL::IdString &name)
-	{
-		// Class member namespace.
-		return mangle_name(name);
-	}
-
-	std::string mangle(const RTLIL::Module *module)
-	{
-		return mangle_module_name(module->name, /*is_blackbox=*/module->get_bool_attribute(ID(cxxrtl_blackbox)));
-	}
-
-	std::string mangle(const RTLIL::Memory *memory)
-	{
-		return mangle_memory_name(memory->name);
-	}
-
-	std::string mangle(const RTLIL::Cell *cell)
-	{
-		return mangle_cell_name(cell->name);
-	}
-
-	std::string mangle(const RTLIL::Wire *wire)
-	{
-		return mangle_wire_name(wire->name);
-	}
-
-	std::string mangle(RTLIL::SigBit sigbit)
-	{
-		log_assert(sigbit.wire != NULL);
-		if (sigbit.wire->width == 1)
-			return mangle(sigbit.wire);
-		return mangle(sigbit.wire) + "_" + std::to_string(sigbit.offset);
-	}
-
-	std::vector<std::string> template_param_names(const RTLIL::Module *module)
-	{
-		if (!module->has_attribute(ID(cxxrtl_template)))
-			return {};
-
-		if (module->attributes.at(ID(cxxrtl_template)).flags != RTLIL::CONST_FLAG_STRING)
-			log_cmd_error("Attribute `cxxrtl_template' of module `%s' is not a string.\n", log_id(module));
-
-		std::vector<std::string> param_names = split_by(module->get_string_attribute(ID(cxxrtl_template)), " \t");
-		for (const auto &param_name : param_names) {
-			// Various lowercase prefixes (p_, i_, cell_, ...) are used for member variables, so require
-			// parameters to start with an uppercase letter to avoid name conflicts. (This is the convention
-			// in both Verilog and C++, anyway.)
-			if (!isupper(param_name[0]))
-				log_cmd_error("Attribute `cxxrtl_template' of module `%s' includes a parameter `%s', "
-				              "which does not start with an uppercase letter.\n",
-				              log_id(module), param_name.c_str());
-		}
-		return param_names;
-	}
-
-	std::string template_params(const RTLIL::Module *module, bool is_decl)
-	{
-		std::vector<std::string> param_names = template_param_names(module);
-		if (param_names.empty())
-			return "";
-
-		std::string params = "<";
-		bool first = true;
-		for (const auto &param_name : param_names) {
-			if (!first)
-				params += ", ";
-			first = false;
-			if (is_decl)
-				params += "size_t ";
-			params += param_name;
-		}
-		params += ">";
-		return params;
-	}
-
-	std::string template_args(const RTLIL::Cell *cell)
-	{
-		RTLIL::Module *cell_module = cell->module->design->module(cell->type);
-		log_assert(cell_module != nullptr);
-		if (!cell_module->get_bool_attribute(ID(cxxrtl_blackbox)))
-			return "";
-
-		std::vector<std::string> param_names = template_param_names(cell_module);
-		if (param_names.empty())
-			return "";
-
-		std::string params = "<";
-		bool first = true;
-		for (const auto &param_name : param_names) {
-			if (!first)
-				params += ", ";
-			first = false;
-			params += "/*" + param_name + "=*/";
-			RTLIL::IdString id_param_name = '\\' + param_name;
-			if (!cell->hasParam(id_param_name))
-				log_cmd_error("Cell `%s.%s' does not have a parameter `%s', which is required by the templated module `%s'.\n",
-				              log_id(cell->module), log_id(cell), param_name.c_str(), log_id(cell_module));
-			RTLIL::Const param_value = cell->getParam(id_param_name);
-			if (((param_value.flags & ~RTLIL::CONST_FLAG_SIGNED) != 0) || param_value.as_int() < 0)
-				log_cmd_error("Parameter `%s' of cell `%s.%s', which is required by the templated module `%s', "
-				              "is not a positive integer.\n",
-				              param_name.c_str(), log_id(cell->module), log_id(cell), log_id(cell_module));
-			params += std::to_string(cell->getParam(id_param_name).as_int());
-		}
-		params += ">";
-		return params;
-	}
-
-	std::string fresh_temporary()
-	{
-		return stringf("tmp_%d", temporary++);
-	}
-
-	void dump_attrs(const RTLIL::AttrObject *object)
-	{
-		for (auto attr : object->attributes) {
-			f << indent << "// " << attr.first.str() << ": ";
-			if (attr.second.flags & RTLIL::CONST_FLAG_STRING) {
-				f << attr.second.decode_string();
-			} else {
-				f << attr.second.as_int(/*is_signed=*/attr.second.flags & RTLIL::CONST_FLAG_SIGNED);
-			}
-			f << "\n";
-		}
-	}
-
-	void dump_const_init(const RTLIL::Const &data, int width, int offset = 0, bool fixed_width = false)
-	{
-		const int CHUNK_SIZE = 32;
-		f << "{";
-		while (width > 0) {
-			int chunk_width = min(width, CHUNK_SIZE);
-			uint32_t chunk = data.extract(offset, chunk_width).as_int();
-			if (fixed_width)
-				f << stringf("0x%.*xu", (3 + chunk_width) / 4, chunk);
-			else
-				f << stringf("%#xu", chunk);
-			if (width > CHUNK_SIZE)
-				f << ',';
-			offset += CHUNK_SIZE;
-			width  -= CHUNK_SIZE;
-		}
-		f << "}";
-	}
-
-	void dump_const_init(const RTLIL::Const &data)
-	{
-		dump_const_init(data, data.size());
-	}
-
-	void dump_const(const RTLIL::Const &data, int width, int offset = 0, bool fixed_width = false)
-	{
-		f << "value<" << width << ">";
-		dump_const_init(data, width, offset, fixed_width);
-	}
-
-	void dump_const(const RTLIL::Const &data)
-	{
-		dump_const(data, data.size());
-	}
-
-	bool dump_sigchunk(const RTLIL::SigChunk &chunk, bool is_lhs)
-	{
-		if (chunk.wire == NULL) {
-			dump_const(chunk.data, chunk.width, chunk.offset);
-			return false;
-		} else {
-			if (!is_lhs && elided_wires.count(chunk.wire)) {
-				const FlowGraph::Node &node = elided_wires[chunk.wire];
-				switch (node.type) {
-					case FlowGraph::Node::Type::CONNECT:
-						dump_connect_elided(node.connect);
-						break;
-					case FlowGraph::Node::Type::CELL_EVAL:
-						log_assert(is_elidable_cell(node.cell->type));
-						dump_cell_elided(node.cell);
-						break;
-					default:
-						log_assert(false);
-				}
-			} else if (localized_wires[chunk.wire] || is_input_wire(chunk.wire)) {
-				f << mangle(chunk.wire);
-			} else {
-				f << mangle(chunk.wire) << (is_lhs ? ".next" : ".curr");
-			}
-			if (chunk.width == chunk.wire->width && chunk.offset == 0)
-				return false;
-			else if (chunk.width == 1)
-				f << ".slice<" << chunk.offset << ">()";
-			else
-				f << ".slice<" << chunk.offset+chunk.width-1 << "," << chunk.offset << ">()";
-			return true;
-		}
-	}
-
-	bool dump_sigspec(const RTLIL::SigSpec &sig, bool is_lhs)
-	{
-		if (sig.empty()) {
-			f << "value<0>()";
-			return false;
-		} else if (sig.is_chunk()) {
-			return dump_sigchunk(sig.as_chunk(), is_lhs);
-		} else {
-			dump_sigchunk(*sig.chunks().rbegin(), is_lhs);
-			for (auto it = sig.chunks().rbegin() + 1; it != sig.chunks().rend(); ++it) {
-				f << ".concat(";
-				dump_sigchunk(*it, is_lhs);
-				f << ")";
-			}
-			return true;
-		}
-	}
-
-	void dump_sigspec_lhs(const RTLIL::SigSpec &sig)
-	{
-		dump_sigspec(sig, /*is_lhs=*/true);
-	}
-
-	void dump_sigspec_rhs(const RTLIL::SigSpec &sig)
-	{
-		// In the contexts where we want template argument deduction to occur for `template<size_t Bits> ... value<Bits>`,
-		// it is necessary to have the argument to already be a `value<N>`, since template argument deduction and implicit
-		// type conversion are mutually exclusive. In these contexts, we use dump_sigspec_rhs() to emit an explicit
-		// type conversion, but only if the expression needs it.
-		bool is_complex = dump_sigspec(sig, /*is_lhs=*/false);
-		if (is_complex)
-			f << ".val()";
-	}
-
-	void collect_sigspec_rhs(const RTLIL::SigSpec &sig, std::vector<RTLIL::IdString> &cells)
-	{
-		for (auto chunk : sig.chunks()) {
-			if (!chunk.wire || !elided_wires.count(chunk.wire))
-				continue;
-
-			const FlowGraph::Node &node = elided_wires[chunk.wire];
-			switch (node.type) {
-				case FlowGraph::Node::Type::CONNECT:
-					collect_connect(node.connect, cells);
-					break;
-				case FlowGraph::Node::Type::CELL_EVAL:
-					collect_cell_eval(node.cell, cells);
-					break;
-				default:
-					log_assert(false);
-			}
-		}
-	}
-
-	void dump_connect_elided(const RTLIL::SigSig &conn)
-	{
-		dump_sigspec_rhs(conn.second);
-	}
-
-	bool is_connect_elided(const RTLIL::SigSig &conn)
-	{
-		return conn.first.is_wire() && elided_wires.count(conn.first.as_wire());
-	}
-
-	void collect_connect(const RTLIL::SigSig &conn, std::vector<RTLIL::IdString> &cells)
-	{
-		if (!is_connect_elided(conn))
-			return;
-
-		collect_sigspec_rhs(conn.second, cells);
-	}
-
-	void dump_connect(const RTLIL::SigSig &conn)
-	{
-		if (is_connect_elided(conn))
-			return;
-
-		f << indent << "// connection\n";
-		f << indent;
-		dump_sigspec_lhs(conn.first);
-		f << " = ";
-		dump_connect_elided(conn);
-		f << ";\n";
-	}
-
-	void dump_cell_sync(const RTLIL::Cell *cell)
-	{
-		const char *access = is_cxxrtl_blackbox_cell(cell) ? "->" : ".";
-		f << indent << "// cell " << cell->name.str() << " syncs\n";
-		for (auto conn : cell->connections())
-			if (cell->output(conn.first))
-				if (is_cxxrtl_sync_port(cell, conn.first)) {
-					f << indent;
-					dump_sigspec_lhs(conn.second);
-					f << " = " << mangle(cell) << access << mangle_wire_name(conn.first) << ".curr;\n";
-				}
-	}
-
-	void dump_cell_elided(const RTLIL::Cell *cell)
-	{
-		// Unary cells
-		if (is_unary_cell(cell->type)) {
-			f << cell->type.substr(1) << '_' <<
-			     (cell->getParam(ID::A_SIGNED).as_bool() ? 's' : 'u') <<
-			     "<" << cell->getParam(ID::Y_WIDTH).as_int() << ">(";
-			dump_sigspec_rhs(cell->getPort(ID::A));
-			f << ")";
-		// Binary cells
-		} else if (is_binary_cell(cell->type)) {
-			f << cell->type.substr(1) << '_' <<
-			     (cell->getParam(ID::A_SIGNED).as_bool() ? 's' : 'u') <<
-			     (cell->getParam(ID::B_SIGNED).as_bool() ? 's' : 'u') <<
-			     "<" << cell->getParam(ID::Y_WIDTH).as_int() << ">(";
-			dump_sigspec_rhs(cell->getPort(ID::A));
-			f << ", ";
-			dump_sigspec_rhs(cell->getPort(ID::B));
-			f << ")";
-		// Muxes
-		} else if (cell->type == ID($mux)) {
-			f << "(";
-			dump_sigspec_rhs(cell->getPort(ID::S));
-			f << " ? ";
-			dump_sigspec_rhs(cell->getPort(ID::B));
-			f << " : ";
-			dump_sigspec_rhs(cell->getPort(ID::A));
-			f << ")";
-		// Concats
-		} else if (cell->type == ID($concat)) {
-			dump_sigspec_rhs(cell->getPort(ID::B));
-			f << ".concat(";
-			dump_sigspec_rhs(cell->getPort(ID::A));
-			f << ").val()";
-		// Slices
-		} else if (cell->type == ID($slice)) {
-			dump_sigspec_rhs(cell->getPort(ID::A));
-			f << ".slice<";
-			f << cell->getParam(ID::OFFSET).as_int() + cell->getParam(ID::Y_WIDTH).as_int() - 1;
-			f << ",";
-			f << cell->getParam(ID::OFFSET).as_int();
-			f << ">().val()";
-		} else {
-			log_assert(false);
-		}
-	}
-
-	bool is_cell_elided(const RTLIL::Cell *cell)
-	{
-		return is_elidable_cell(cell->type) && cell->hasPort(ID::Y) && cell->getPort(ID::Y).is_wire() &&
-			elided_wires.count(cell->getPort(ID::Y).as_wire());
-	}
-
-	void collect_cell_eval(const RTLIL::Cell *cell, std::vector<RTLIL::IdString> &cells)
-	{
-		if (!is_cell_elided(cell))
-			return;
-
-		cells.push_back(cell->name);
-		for (auto port : cell->connections())
-			if (port.first != ID::Y)
-				collect_sigspec_rhs(port.second, cells);
-	}
-
-	void dump_cell_eval(const RTLIL::Cell *cell)
-	{
-		if (is_cell_elided(cell))
-			return;
-		if (cell->type == ID($meminit))
-			return; // Handled elsewhere.
-
-		std::vector<RTLIL::IdString> elided_cells;
-		if (is_elidable_cell(cell->type)) {
-			for (auto port : cell->connections())
-				if (port.first != ID::Y)
-					collect_sigspec_rhs(port.second, elided_cells);
-		}
-		if (elided_cells.empty()) {
-			dump_attrs(cell);
-			f << indent << "// cell " << cell->name.str() << "\n";
-		} else {
-			f << indent << "// cells";
-			for (auto elided_cell : elided_cells)
-				f << " " << elided_cell.str();
-			f << "\n";
-		}
-
-		// Elidable cells
-		if (is_elidable_cell(cell->type)) {
-			f << indent;
-			dump_sigspec_lhs(cell->getPort(ID::Y));
-			f << " = ";
-			dump_cell_elided(cell);
-			f << ";\n";
-		// Parallel (one-hot) muxes
-		} else if (cell->type == ID($pmux)) {
-			int width = cell->getParam(ID::WIDTH).as_int();
-			int s_width = cell->getParam(ID::S_WIDTH).as_int();
-			bool first = true;
-			for (int part = 0; part < s_width; part++) {
-				f << (first ? indent : " else ");
-				first = false;
-				f << "if (";
-				dump_sigspec_rhs(cell->getPort(ID::S).extract(part));
-				f << ") {\n";
-				inc_indent();
-					f << indent;
-					dump_sigspec_lhs(cell->getPort(ID::Y));
-					f << " = ";
-					dump_sigspec_rhs(cell->getPort(ID::B).extract(part * width, width));
-					f << ";\n";
-				dec_indent();
-				f << indent << "}";
-			}
-			f << " else {\n";
-			inc_indent();
-				f << indent;
-				dump_sigspec_lhs(cell->getPort(ID::Y));
-				f << " = ";
-				dump_sigspec_rhs(cell->getPort(ID::A));
-				f << ";\n";
-			dec_indent();
-			f << indent << "}\n";
-		// Flip-flops
-		} else if (is_ff_cell(cell->type)) {
-			if (cell->hasPort(ID::CLK) && cell->getPort(ID::CLK).is_wire()) {
-				// Edge-sensitive logic
-				RTLIL::SigBit clk_bit = cell->getPort(ID::CLK)[0];
-				clk_bit = sigmaps[clk_bit.wire->module](clk_bit);
-				f << indent << "if (" << (cell->getParam(ID::CLK_POLARITY).as_bool() ? "posedge_" : "negedge_")
-				            << mangle(clk_bit) << ") {\n";
-				inc_indent();
-					if (cell->type == ID($dffe)) {
-						f << indent << "if (";
-						dump_sigspec_rhs(cell->getPort(ID::EN));
-						f << " == value<1> {" << cell->getParam(ID::EN_POLARITY).as_bool() << "u}) {\n";
-						inc_indent();
-					}
-					f << indent;
-					dump_sigspec_lhs(cell->getPort(ID::Q));
-					f << " = ";
-					dump_sigspec_rhs(cell->getPort(ID::D));
-					f << ";\n";
-					if (cell->type == ID($dffe)) {
-						dec_indent();
-						f << indent << "}\n";
-					}
-				dec_indent();
-				f << indent << "}\n";
-			} else if (cell->hasPort(ID::EN)) {
-				// Level-sensitive logic
-				f << indent << "if (";
-				dump_sigspec_rhs(cell->getPort(ID::EN));
-				f << " == value<1> {" << cell->getParam(ID::EN_POLARITY).as_bool() << "u}) {\n";
-				inc_indent();
-					f << indent;
-					dump_sigspec_lhs(cell->getPort(ID::Q));
-					f << " = ";
-					dump_sigspec_rhs(cell->getPort(ID::D));
-					f << ";\n";
-				dec_indent();
-				f << indent << "}\n";
-			}
-			if (cell->hasPort(ID::ARST)) {
-				// Asynchronous reset (entire coarse cell at once)
-				f << indent << "if (";
-				dump_sigspec_rhs(cell->getPort(ID::ARST));
-				f << " == value<1> {" << cell->getParam(ID::ARST_POLARITY).as_bool() << "u}) {\n";
-				inc_indent();
-					f << indent;
-					dump_sigspec_lhs(cell->getPort(ID::Q));
-					f << " = ";
-					dump_const(cell->getParam(ID::ARST_VALUE));
-					f << ";\n";
-				dec_indent();
-				f << indent << "}\n";
-			}
-			if (cell->hasPort(ID::SET)) {
-				// Asynchronous set (for individual bits)
-				f << indent;
-				dump_sigspec_lhs(cell->getPort(ID::Q));
-				f << " = ";
-				dump_sigspec_lhs(cell->getPort(ID::Q));
-				f << ".update(";
-				dump_const(RTLIL::Const(RTLIL::S1, cell->getParam(ID::WIDTH).as_int()));
-				f << ", ";
-				dump_sigspec_rhs(cell->getPort(ID::SET));
-				f << (cell->getParam(ID::SET_POLARITY).as_bool() ? "" : ".bit_not()") << ");\n";
-			}
-			if (cell->hasPort(ID::CLR)) {
-				// Asynchronous clear (for individual bits; priority over set)
-				f << indent;
-				dump_sigspec_lhs(cell->getPort(ID::Q));
-				f << " = ";
-				dump_sigspec_lhs(cell->getPort(ID::Q));
-				f << ".update(";
-				dump_const(RTLIL::Const(RTLIL::S0, cell->getParam(ID::WIDTH).as_int()));
-				f << ", ";
-				dump_sigspec_rhs(cell->getPort(ID::CLR));
-				f << (cell->getParam(ID::CLR_POLARITY).as_bool() ? "" : ".bit_not()") << ");\n";
-			}
-		// Memory ports
-		} else if (cell->type.in(ID($memrd), ID($memwr))) {
-			if (cell->getParam(ID::CLK_ENABLE).as_bool()) {
-				RTLIL::SigBit clk_bit = cell->getPort(ID::CLK)[0];
-				clk_bit = sigmaps[clk_bit.wire->module](clk_bit);
-				f << indent << "if (" << (cell->getParam(ID::CLK_POLARITY).as_bool() ? "posedge_" : "negedge_")
-				            << mangle(clk_bit) << ") {\n";
-				inc_indent();
-			}
-			RTLIL::Memory *memory = cell->module->memories[cell->getParam(ID::MEMID).decode_string()];
-			std::string valid_index_temp = fresh_temporary();
-			f << indent << "auto " << valid_index_temp << " = memory_index(";
-			dump_sigspec_rhs(cell->getPort(ID::ADDR));
-			f << ", " << memory->start_offset << ", " << memory->size << ");\n";
-			if (cell->type == ID($memrd)) {
-				bool has_enable = cell->getParam(ID::CLK_ENABLE).as_bool() && !cell->getPort(ID::EN).is_fully_ones();
-				if (has_enable) {
-					f << indent << "if (";
-					dump_sigspec_rhs(cell->getPort(ID::EN));
-					f << ") {\n";
-					inc_indent();
-				}
-				// The generated code has two bounds checks; one in an assertion, and another that guards the read.
-				// This is done so that the code does not invoke undefined behavior under any conditions, but nevertheless
-				// loudly crashes if an illegal condition is encountered. The assert may be turned off with -NDEBUG not
-				// just for release builds, but also to make sure the simulator (which is presumably embedded in some
-				// larger program) will never crash the code that calls into it.
-				//
-				// If assertions are disabled, out of bounds reads are defined to return zero.
-				f << indent << "assert(" << valid_index_temp << ".valid && \"out of bounds read\");\n";
-				f << indent << "if(" << valid_index_temp << ".valid) {\n";
-				inc_indent();
-					if (writable_memories[memory]) {
-						std::string addr_temp = fresh_temporary();
-						f << indent << "const value<" << cell->getPort(ID::ADDR).size() << "> &" << addr_temp << " = ";
-						dump_sigspec_rhs(cell->getPort(ID::ADDR));
-						f << ";\n";
-						std::string lhs_temp = fresh_temporary();
-						f << indent << "value<" << memory->width << "> " << lhs_temp << " = "
-						            << mangle(memory) << "[" << valid_index_temp << ".index];\n";
-						std::vector<const RTLIL::Cell*> memwr_cells(transparent_for[cell].begin(), transparent_for[cell].end());
-						std::sort(memwr_cells.begin(), memwr_cells.end(),
-							[](const RTLIL::Cell *a, const RTLIL::Cell *b) {
-								return a->getParam(ID::PRIORITY).as_int() < b->getParam(ID::PRIORITY).as_int();
-							});
-						for (auto memwr_cell : memwr_cells) {
-							f << indent << "if (" << addr_temp << " == ";
-							dump_sigspec_rhs(memwr_cell->getPort(ID::ADDR));
-							f << ") {\n";
-							inc_indent();
-								f << indent << lhs_temp << " = " << lhs_temp;
-								f << ".update(";
-								dump_sigspec_rhs(memwr_cell->getPort(ID::DATA));
-								f << ", ";
-								dump_sigspec_rhs(memwr_cell->getPort(ID::EN));
-								f << ");\n";
-							dec_indent();
-							f << indent << "}\n";
-						}
-						f << indent;
-						dump_sigspec_lhs(cell->getPort(ID::DATA));
-						f << " = " << lhs_temp << ";\n";
-					} else {
-						f << indent;
-						dump_sigspec_lhs(cell->getPort(ID::DATA));
-						f << " = " << mangle(memory) << "[" << valid_index_temp << ".index];\n";
-					}
-				dec_indent();
-				f << indent << "} else {\n";
-				inc_indent();
-					f << indent;
-					dump_sigspec_lhs(cell->getPort(ID::DATA));
-					f << " = value<" << memory->width << "> {};\n";
-				dec_indent();
-				f << indent << "}\n";
-				if (has_enable) {
-					dec_indent();
-					f << indent << "}\n";
-				}
-			} else /*if (cell->type == ID($memwr))*/ {
-				log_assert(writable_memories[memory]);
-				// See above for rationale of having both the assert and the condition.
-				//
-				// If assertions are disabled, out of bounds writes are defined to do nothing.
-				f << indent << "assert(" << valid_index_temp << ".valid && \"out of bounds write\");\n";
-				f << indent << "if (" << valid_index_temp << ".valid) {\n";
-				inc_indent();
-					f << indent << mangle(memory) << ".update(" << valid_index_temp << ".index, ";
-					dump_sigspec_rhs(cell->getPort(ID::DATA));
-					f << ", ";
-					dump_sigspec_rhs(cell->getPort(ID::EN));
-					f << ", " << cell->getParam(ID::PRIORITY).as_int() << ");\n";
-				dec_indent();
-				f << indent << "}\n";
-			}
-			if (cell->getParam(ID::CLK_ENABLE).as_bool()) {
-				dec_indent();
-				f << indent << "}\n";
-			}
-		// Internal cells
-		} else if (is_internal_cell(cell->type)) {
-			log_cmd_error("Unsupported internal cell `%s'.\n", cell->type.c_str());
-		// User cells
-		} else {
-			log_assert(cell->known());
-			const char *access = is_cxxrtl_blackbox_cell(cell) ? "->" : ".";
-			for (auto conn : cell->connections())
-				if (cell->input(conn.first) && !cell->output(conn.first)) {
-					f << indent << mangle(cell) << access << mangle_wire_name(conn.first) << " = ";
-					dump_sigspec_rhs(conn.second);
-					f << ";\n";
-					if (getenv("CXXRTL_VOID_MY_WARRANTY")) {
-						// Until we have proper clock tree detection, this really awful hack that opportunistically
-						// propagates prev_* values for clocks can be used to estimate how much faster a design could
-						// be if only one clock edge was simulated by replacing:
-						//   top.p_clk = value<1>{0u}; top.step();
-						//   top.p_clk = value<1>{1u}; top.step();
-						// with:
-						//   top.prev_p_clk = value<1>{0u}; top.p_clk = value<1>{1u}; top.step();
-						// Don't rely on this; it will be removed without warning.
-						RTLIL::Module *cell_module = cell->module->design->module(cell->type);
-						if (cell_module != nullptr && cell_module->wire(conn.first) && conn.second.is_wire()) {
-							RTLIL::Wire *cell_module_wire = cell_module->wire(conn.first);
-							if (edge_wires[conn.second.as_wire()] && edge_wires[cell_module_wire]) {
-								f << indent << mangle(cell) << access << "prev_" << mangle(cell_module_wire) << " = ";
-								f << "prev_" << mangle(conn.second.as_wire()) << ";\n";
-							}
-						}
-					}
-				} else if (cell->input(conn.first)) {
-					f << indent << mangle(cell) << access << mangle_wire_name(conn.first) << ".next = ";
-					dump_sigspec_rhs(conn.second);
-					f << ";\n";
-				}
-			auto assign_from_outputs = [&](bool cell_converged) {
-				for (auto conn : cell->connections()) {
-					if (cell->output(conn.first)) {
-						if (conn.second.empty())
-							continue; // ignore disconnected ports
-						if (is_cxxrtl_sync_port(cell, conn.first))
-							continue; // fully sync ports are handled in CELL_SYNC nodes
-						f << indent;
-						dump_sigspec_lhs(conn.second);
-						f << " = " << mangle(cell) << access << mangle_wire_name(conn.first);
-						// Similarly to how there is no purpose to buffering cell inputs, there is also no purpose to buffering
-						// combinatorial cell outputs in case the cell converges within one cycle. (To convince yourself that
-						// this optimization is valid, consider that, since the cell converged within one cycle, it would not
-						// have any buffered wires if they were not output ports. Imagine inlining the cell's eval() function,
-						// and consider the fate of the localized wires that used to be output ports.)
-						//
-						// Unlike cell inputs (which are never buffered), it is not possible to know apriori whether the cell
-						// (which may be late bound) will converge immediately. Because of this, the choice between using .curr
-						// (appropriate for buffered outputs) and .next (appropriate for unbuffered outputs) is made at runtime.
-						if (cell_converged && is_cxxrtl_comb_port(cell, conn.first))
-							f << ".next;\n";
-						else
-							f << ".curr;\n";
-					}
-				}
-			};
-			f << indent << "if (" << mangle(cell) << access << "eval()) {\n";
-			inc_indent();
-				assign_from_outputs(/*cell_converged=*/true);
-			dec_indent();
-			f << indent << "} else {\n";
-			inc_indent();
-				f << indent << "converged = false;\n";
-				assign_from_outputs(/*cell_converged=*/false);
-			dec_indent();
-			f << indent << "}\n";
-		}
-	}
-
-	void dump_assign(const RTLIL::SigSig &sigsig)
-	{
-		f << indent;
-		dump_sigspec_lhs(sigsig.first);
-		f << " = ";
-		dump_sigspec_rhs(sigsig.second);
-		f << ";\n";
-	}
-
-	void dump_case_rule(const RTLIL::CaseRule *rule)
-	{
-		for (auto action : rule->actions)
-			dump_assign(action);
-		for (auto switch_ : rule->switches)
-			dump_switch_rule(switch_);
-	}
-
-	void dump_switch_rule(const RTLIL::SwitchRule *rule)
-	{
-		// The switch attributes are printed before the switch condition is captured.
-		dump_attrs(rule);
-		std::string signal_temp = fresh_temporary();
-		f << indent << "const value<" << rule->signal.size() << "> &" << signal_temp << " = ";
-		dump_sigspec(rule->signal, /*is_lhs=*/false);
-		f << ";\n";
-
-		bool first = true;
-		for (auto case_ : rule->cases) {
-			// The case attributes (for nested cases) are printed before the if/else if/else statement.
-			dump_attrs(rule);
-			f << indent;
-			if (!first)
-				f << "} else ";
-			first = false;
-			if (!case_->compare.empty()) {
-				f << "if (";
-				bool first = true;
-				for (auto &compare : case_->compare) {
-					if (!first)
-						f << " || ";
-					first = false;
-					if (compare.is_fully_def()) {
-						f << signal_temp << " == ";
-						dump_sigspec(compare, /*is_lhs=*/false);
-					} else if (compare.is_fully_const()) {
-						RTLIL::Const compare_mask, compare_value;
-						for (auto bit : compare.as_const()) {
-							switch (bit) {
-								case RTLIL::S0:
-								case RTLIL::S1:
-									compare_mask.bits.push_back(RTLIL::S1);
-									compare_value.bits.push_back(bit);
-									break;
-
-								case RTLIL::Sx:
-								case RTLIL::Sz:
-								case RTLIL::Sa:
-									compare_mask.bits.push_back(RTLIL::S0);
-									compare_value.bits.push_back(RTLIL::S0);
-									break;
-
-								default:
-									log_assert(false);
-							}
-						}
-						f << "and_uu<" << compare.size() << ">(" << signal_temp << ", ";
-						dump_const(compare_mask);
-						f << ") == ";
-						dump_const(compare_value);
-					} else {
-						log_assert(false);
-					}
-				}
-				f << ") ";
-			}
-			f << "{\n";
-			inc_indent();
-				dump_case_rule(case_);
-			dec_indent();
-		}
-		f << indent << "}\n";
-	}
-
-	void dump_process(const RTLIL::Process *proc)
-	{
-		dump_attrs(proc);
-		f << indent << "// process " << proc->name.str() << "\n";
-		// The case attributes (for root case) are always empty.
-		log_assert(proc->root_case.attributes.empty());
-		dump_case_rule(&proc->root_case);
-		for (auto sync : proc->syncs) {
-			RTLIL::SigBit sync_bit;
-			if (!sync->signal.empty()) {
-				sync_bit = sync->signal[0];
-				sync_bit = sigmaps[sync_bit.wire->module](sync_bit);
-			}
-
-			pool<std::string> events;
-			switch (sync->type) {
-				case RTLIL::STp:
-					log_assert(sync_bit.wire != nullptr);
-					events.insert("posedge_" + mangle(sync_bit));
-					break;
-				case RTLIL::STn:
-					log_assert(sync_bit.wire != nullptr);
-					events.insert("negedge_" + mangle(sync_bit));
-					break;
-				case RTLIL::STe:
-					log_assert(sync_bit.wire != nullptr);
-					events.insert("posedge_" + mangle(sync_bit));
-					events.insert("negedge_" + mangle(sync_bit));
-					break;
-
-				case RTLIL::STa:
-					events.insert("true");
-					break;
-
-				case RTLIL::ST0:
-				case RTLIL::ST1:
-				case RTLIL::STg:
-				case RTLIL::STi:
-					log_assert(false);
-			}
-			if (!events.empty()) {
-				f << indent << "if (";
-				bool first = true;
-				for (auto &event : events) {
-					if (!first)
-						f << " || ";
-					first = false;
-					f << event;
-				}
-				f << ") {\n";
-				inc_indent();
-					for (auto action : sync->actions)
-						dump_assign(action);
-				dec_indent();
-				f << indent << "}\n";
-			}
-		}
-	}
-
-	void dump_wire(const RTLIL::Wire *wire, bool is_local_context)
-	{
-		if (elided_wires.count(wire))
-			return;
-		if (localized_wires.count(wire) != is_local_context)
-			return;
-
-		if (is_local_context) {
-			dump_attrs(wire);
-			f << indent << "value<" << wire->width << "> " << mangle(wire) << ";\n";
-		} else {
-			std::string width;
-			if (wire->module->has_attribute(ID(cxxrtl_blackbox)) && wire->has_attribute(ID(cxxrtl_width))) {
-				width = wire->get_string_attribute(ID(cxxrtl_width));
-			} else {
-				width = std::to_string(wire->width);
-			}
-
-			dump_attrs(wire);
-			f << indent << (is_input_wire(wire) ? "value" : "wire") << "<" << width << "> " << mangle(wire);
-			if (wire->has_attribute(ID::init)) {
-				f << " ";
-				dump_const_init(wire->attributes.at(ID::init));
-			}
-			f << ";\n";
-			if (edge_wires[wire]) {
-				if (is_input_wire(wire)) {
-					f << indent << "value<" << width << "> prev_" << mangle(wire);
-					if (wire->has_attribute(ID::init)) {
-						f << " ";
-						dump_const_init(wire->attributes.at(ID::init));
-					}
-					f << ";\n";
-				}
-				for (auto edge_type : edge_types) {
-					if (edge_type.first.wire == wire) {
-						std::string prev, next;
-						if (is_input_wire(wire)) {
-							prev = "prev_" + mangle(edge_type.first.wire);
-							next =           mangle(edge_type.first.wire);
-						} else {
-							prev = mangle(edge_type.first.wire) + ".curr";
-							next = mangle(edge_type.first.wire) + ".next";
-						}
-						prev += ".slice<" + std::to_string(edge_type.first.offset) + ">().val()";
-						next += ".slice<" + std::to_string(edge_type.first.offset) + ">().val()";
-						if (edge_type.second != RTLIL::STn) {
-							f << indent << "bool posedge_" << mangle(edge_type.first) << "() const {\n";
-							inc_indent();
-								f << indent << "return !" << prev << " && " << next << ";\n";
-							dec_indent();
-							f << indent << "}\n";
-						}
-						if (edge_type.second != RTLIL::STp) {
-							f << indent << "bool negedge_" << mangle(edge_type.first) << "() const {\n";
-							inc_indent();
-								f << indent << "return " << prev << " && !" << next << ";\n";
-							dec_indent();
-							f << indent << "}\n";
-						}
-					}
-				}
-			}
-		}
-	}
-
-	void dump_memory(RTLIL::Module *module, const RTLIL::Memory *memory)
-	{
-		vector<const RTLIL::Cell*> init_cells;
-		for (auto cell : module->cells())
-			if (cell->type == ID($meminit) && cell->getParam(ID::MEMID).decode_string() == memory->name.str())
-				init_cells.push_back(cell);
-
-		std::sort(init_cells.begin(), init_cells.end(), [](const RTLIL::Cell *a, const RTLIL::Cell *b) {
-			int a_addr = a->getPort(ID::ADDR).as_int(), b_addr = b->getPort(ID::ADDR).as_int();
-			int a_prio = a->getParam(ID::PRIORITY).as_int(), b_prio = b->getParam(ID::PRIORITY).as_int();
-			return a_prio > b_prio || (a_prio == b_prio && a_addr < b_addr);
-		});
-
-		dump_attrs(memory);
-		f << indent << "memory<" << memory->width << "> " << mangle(memory)
-		            << " { " << memory->size << "u";
-		if (init_cells.empty()) {
-			f << " };\n";
-		} else {
-			f << ",\n";
-			inc_indent();
-				for (auto cell : init_cells) {
-					dump_attrs(cell);
-					RTLIL::Const data = cell->getPort(ID::DATA).as_const();
-					size_t width = cell->getParam(ID::WIDTH).as_int();
-					size_t words = cell->getParam(ID::WORDS).as_int();
-					f << indent << "memory<" << memory->width << ">::init<" << words << "> { "
-					            << stringf("%#x", cell->getPort(ID::ADDR).as_int()) << ", {";
-					inc_indent();
-						for (size_t n = 0; n < words; n++) {
-							if (n % 4 == 0)
-								f << "\n" << indent;
-							else
-								f << " ";
-							dump_const(data, width, n * width, /*fixed_width=*/true);
-							f << ",";
-						}
-					dec_indent();
-					f << "\n" << indent << "}},\n";
-				}
-			dec_indent();
-			f << indent << "};\n";
-		}
-	}
-
-	void dump_eval_method(RTLIL::Module *module)
-	{
-		inc_indent();
-			f << indent << "bool converged = " << (eval_converges.at(module) ? "true" : "false") << ";\n";
-			if (!module->get_bool_attribute(ID(cxxrtl_blackbox))) {
-				for (auto wire : module->wires()) {
-					if (edge_wires[wire]) {
-						for (auto edge_type : edge_types) {
-							if (edge_type.first.wire == wire) {
-								if (edge_type.second != RTLIL::STn) {
-									f << indent << "bool posedge_" << mangle(edge_type.first) << " = ";
-									f << "this->posedge_" << mangle(edge_type.first) << "();\n";
-								}
-								if (edge_type.second != RTLIL::STp) {
-									f << indent << "bool negedge_" << mangle(edge_type.first) << " = ";
-									f << "this->negedge_" << mangle(edge_type.first) << "();\n";
-								}
-							}
-						}
-					}
-				}
-				for (auto wire : module->wires())
-					dump_wire(wire, /*is_local_context=*/true);
-				for (auto node : schedule[module]) {
-					switch (node.type) {
-						case FlowGraph::Node::Type::CONNECT:
-							dump_connect(node.connect);
-							break;
-						case FlowGraph::Node::Type::CELL_SYNC:
-							dump_cell_sync(node.cell);
-							break;
-						case FlowGraph::Node::Type::CELL_EVAL:
-							dump_cell_eval(node.cell);
-							break;
-						case FlowGraph::Node::Type::PROCESS:
-							dump_process(node.process);
-							break;
-					}
-				}
-			}
-			f << indent << "return converged;\n";
-		dec_indent();
-	}
-
-	void dump_commit_method(RTLIL::Module *module)
-	{
-		inc_indent();
-			f << indent << "bool changed = false;\n";
-			for (auto wire : module->wires()) {
-				if (elided_wires.count(wire) || localized_wires.count(wire))
-					continue;
-				if (is_input_wire(wire)) {
-					if (edge_wires[wire])
-						f << indent << "prev_" << mangle(wire) << " = " << mangle(wire) << ";\n";
-					continue;
-				}
-				if (!module->get_bool_attribute(ID(cxxrtl_blackbox)) || wire->port_id != 0)
-					f << indent << "changed |= " << mangle(wire) << ".commit();\n";
-			}
-			if (!module->get_bool_attribute(ID(cxxrtl_blackbox))) {
-				for (auto memory : module->memories) {
-					if (!writable_memories[memory.second])
-						continue;
-					f << indent << "changed |= " << mangle(memory.second) << ".commit();\n";
-				}
-				for (auto cell : module->cells()) {
-					if (is_internal_cell(cell->type))
-						continue;
-					const char *access = is_cxxrtl_blackbox_cell(cell) ? "->" : ".";
-					f << indent << "changed |= " << mangle(cell) << access << "commit();\n";
-				}
-			}
-			f << indent << "return changed;\n";
-		dec_indent();
-	}
-
-	void dump_debug_info_method(RTLIL::Module *module)
-	{
-		inc_indent();
-			f << indent << "assert(path.empty() || path[path.size() - 1] == ' ');\n";
-			for (auto wire : module->wires()) {
-				if (wire->name[0] != '\\')
-					continue;
-				if (localized_wires.count(wire))
-					continue;
-				f << indent << "items.emplace(path + " << escape_cxx_string(get_hdl_name(wire));
-				f << ", debug_item(" << mangle(wire) << "));\n";
-			}
-			for (auto &memory_it : module->memories) {
-				if (memory_it.first[0] != '\\')
-					continue;
-				f << indent << "items.emplace(path + " << escape_cxx_string(get_hdl_name(memory_it.second));
-				f << ", debug_item(" << mangle(memory_it.second) << "));\n";
-			}
-			for (auto cell : module->cells()) {
-				if (is_internal_cell(cell->type))
-					continue;
-				const char *access = is_cxxrtl_blackbox_cell(cell) ? "->" : ".";
-				f << indent << mangle(cell) << access << "debug_info(items, ";
-				f << "path + " << escape_cxx_string(get_hdl_name(cell) + ' ') << ");\n";
-			}
-		dec_indent();
-	}
-
-	void dump_metadata_map(const dict<RTLIL::IdString, RTLIL::Const> &metadata_map)
-	{
-		if (metadata_map.empty()) {
-			f << "metadata_map()";
-			return;
-		}
-		f << "metadata_map({\n";
-		inc_indent();
-			for (auto metadata_item : metadata_map) {
-				if (!metadata_item.first.begins_with("\\"))
-					continue;
-				f << indent << "{ " << escape_cxx_string(metadata_item.first.str().substr(1)) << ", ";
-				if (metadata_item.second.flags & RTLIL::CONST_FLAG_REAL) {
-					f << std::showpoint << std::stod(metadata_item.second.decode_string()) << std::noshowpoint;
-				} else if (metadata_item.second.flags & RTLIL::CONST_FLAG_STRING) {
-					f << escape_cxx_string(metadata_item.second.decode_string());
-				} else {
-					f << metadata_item.second.as_int(/*is_signed=*/metadata_item.second.flags & RTLIL::CONST_FLAG_SIGNED);
-					if (!(metadata_item.second.flags & RTLIL::CONST_FLAG_SIGNED))
-						f << "u";
-				}
-				f << " },\n";
-			}
-		dec_indent();
-		f << indent << "})";
-	}
-
-	void dump_module_intf(RTLIL::Module *module)
-	{
-		dump_attrs(module);
-		if (module->get_bool_attribute(ID(cxxrtl_blackbox))) {
-			if (module->has_attribute(ID(cxxrtl_template)))
-				f << indent << "template" << template_params(module, /*is_decl=*/true) << "\n";
-			f << indent << "struct " << mangle(module) << " : public module {\n";
-			inc_indent();
-				for (auto wire : module->wires()) {
-					if (wire->port_id != 0)
-						dump_wire(wire, /*is_local_context=*/false);
-				}
-				f << "\n";
-				f << indent << "bool eval() override {\n";
-				dump_eval_method(module);
-				f << indent << "}\n";
-				f << "\n";
-				f << indent << "bool commit() override {\n";
-				dump_commit_method(module);
-				f << indent << "}\n";
-				f << "\n";
-				if (debug_info) {
-					f << indent << "void debug_info(debug_items &items, std::string path = \"\") override {\n";
-					dump_debug_info_method(module);
-					f << indent << "}\n";
-					f << "\n";
-				}
-				f << indent << "static std::unique_ptr<" << mangle(module);
-				f << template_params(module, /*is_decl=*/false) << "> ";
-				f << "create(std::string name, metadata_map parameters, metadata_map attributes);\n";
-			dec_indent();
-			f << indent << "}; // struct " << mangle(module) << "\n";
-			f << "\n";
-			if (blackbox_specializations.count(module)) {
-				// If templated black boxes are used, the constructor of any module which includes the black box cell
-				// (which calls the declared but not defined in the generated code `create` function) may only be used
-				// if (a) the create function is defined in the same translation unit, or (b) the create function has
-				// a forward-declared explicit specialization.
-				//
-				// Option (b) makes it possible to have the generated code and the black box implementation in different
-				// translation units, which is convenient. Of course, its downside is that black boxes must predefine
-				// a specialization for every combination of parameters the generated code may use; but since the main
-				// purpose of templated black boxes is abstracting over datapath width, it is expected that there would
-				// be very few such combinations anyway.
-				for (auto specialization : blackbox_specializations[module]) {
-					f << indent << "template<>\n";
-					f << indent << "std::unique_ptr<" << mangle(module) << specialization << "> ";
-					f << mangle(module) << specialization << "::";
-					f << "create(std::string name, metadata_map parameters, metadata_map attributes);\n";
-					f << "\n";
-				}
-			}
-		} else {
-			f << indent << "struct " << mangle(module) << " : public module {\n";
-			inc_indent();
-				for (auto wire : module->wires())
-					dump_wire(wire, /*is_local_context=*/false);
-				f << "\n";
-				bool has_memories = false;
-				for (auto memory : module->memories) {
-					dump_memory(module, memory.second);
-					has_memories = true;
-				}
-				if (has_memories)
-					f << "\n";
-				bool has_cells = false;
-				for (auto cell : module->cells()) {
-					if (is_internal_cell(cell->type))
-						continue;
-					dump_attrs(cell);
-					RTLIL::Module *cell_module = module->design->module(cell->type);
-					log_assert(cell_module != nullptr);
-					if (cell_module->get_bool_attribute(ID(cxxrtl_blackbox))) {
-						f << indent << "std::unique_ptr<" << mangle(cell_module) << template_args(cell) << "> ";
-						f << mangle(cell) << " = " << mangle(cell_module) << template_args(cell);
-						f << "::create(" << escape_cxx_string(get_hdl_name(cell)) << ", ";
-						dump_metadata_map(cell->parameters);
-						f << ", ";
-						dump_metadata_map(cell->attributes);
-						f << ");\n";
-					} else {
-						f << indent << mangle(cell_module) << " " << mangle(cell) << ";\n";
-					}
-					has_cells = true;
-				}
-				if (has_cells)
-					f << "\n";
-				f << indent << "bool eval() override;\n";
-				f << indent << "bool commit() override;\n";
-				if (debug_info)
-					f << indent << "void debug_info(debug_items &items, std::string path = \"\") override;\n";
-			dec_indent();
-			f << indent << "}; // struct " << mangle(module) << "\n";
-			f << "\n";
-		}
-	}
-
-	void dump_module_impl(RTLIL::Module *module)
-	{
-		if (module->get_bool_attribute(ID(cxxrtl_blackbox)))
-			return;
-		f << indent << "bool " << mangle(module) << "::eval() {\n";
-		dump_eval_method(module);
-		f << indent << "}\n";
-		f << "\n";
-		f << indent << "bool " << mangle(module) << "::commit() {\n";
-		dump_commit_method(module);
-		f << indent << "}\n";
-		f << "\n";
-		if (debug_info) {
-			f << indent << "void " << mangle(module) << "::debug_info(debug_items &items, std::string path) {\n";
-			dump_debug_info_method(module);
-			f << indent << "}\n";
-			f << "\n";
-		}
-	}
-
-	void dump_design(RTLIL::Design *design)
-	{
-		RTLIL::Module *top_module = nullptr;
-		std::vector<RTLIL::Module*> modules;
-		TopoSort<RTLIL::Module*> topo_design;
-		for (auto module : design->modules()) {
-			if (!design->selected_module(module))
-				continue;
-			if (module->get_bool_attribute(ID(cxxrtl_blackbox)))
-				modules.push_back(module); // cxxrtl blackboxes first
-			if (module->get_blackbox_attribute() || module->get_bool_attribute(ID(cxxrtl_blackbox)))
-				continue;
-			if (module->get_bool_attribute(ID::top))
-				top_module = module;
-
-			topo_design.node(module);
-			for (auto cell : module->cells()) {
-				if (is_internal_cell(cell->type) || is_cxxrtl_blackbox_cell(cell))
-					continue;
-				RTLIL::Module *cell_module = design->module(cell->type);
-				log_assert(cell_module != nullptr);
-				topo_design.edge(cell_module, module);
-			}
-		}
-		log_assert(topo_design.sort());
-		modules.insert(modules.end(), topo_design.sorted.begin(), topo_design.sorted.end());
-
-		if (split_intf) {
-			// The only thing more depraved than include guards, is mangling filenames to turn them into include guards.
-			std::string include_guard = design_ns + "_header";
-			std::transform(include_guard.begin(), include_guard.end(), include_guard.begin(), ::toupper);
-
-			f << "#ifndef " << include_guard << "\n";
-			f << "#define " << include_guard << "\n";
-			f << "\n";
-			if (top_module != nullptr && debug_info) {
-				f << "#include <backends/cxxrtl/cxxrtl_capi.h>\n";
-				f << "\n";
-				f << "#ifdef __cplusplus\n";
-				f << "extern \"C\" {\n";
-				f << "#endif\n";
-				f << "\n";
-				f << "cxxrtl_toplevel " << design_ns << "_create();\n";
-				f << "\n";
-				f << "#ifdef __cplusplus\n";
-				f << "}\n";
-				f << "#endif\n";
-				f << "\n";
-			} else {
-				f << "// The CXXRTL C API is not available because the design is built without debug information.\n";
-				f << "\n";
-			}
-			f << "#ifdef __cplusplus\n";
-			f << "\n";
-			f << "#include <backends/cxxrtl/cxxrtl.h>\n";
-			f << "\n";
-			f << "using namespace cxxrtl;\n";
-			f << "\n";
-			f << "namespace " << design_ns << " {\n";
-			f << "\n";
-			for (auto module : modules)
-				dump_module_intf(module);
-			f << "} // namespace " << design_ns << "\n";
-			f << "\n";
-			f << "#endif // __cplusplus\n";
-			f << "\n";
-			f << "#endif\n";
-			*intf_f << f.str(); f.str("");
-		}
-
-		if (split_intf)
-			f << "#include \"" << intf_filename << "\"\n";
-		else
-			f << "#include <backends/cxxrtl/cxxrtl.h>\n";
-		f << "\n";
-		f << "#if defined(CXXRTL_INCLUDE_CAPI_IMPL) || \\\n";
-		f << "    defined(CXXRTL_INCLUDE_VCD_CAPI_IMPL)\n";
-		f << "#include <backends/cxxrtl/cxxrtl_capi.cc>\n";
-		f << "#endif\n";
-		f << "\n";
-		f << "#if defined(CXXRTL_INCLUDE_VCD_CAPI_IMPL)\n";
-		f << "#include <backends/cxxrtl/cxxrtl_vcd_capi.cc>\n";
-		f << "#endif\n";
-		f << "\n";
-		f << "using namespace cxxrtl_yosys;\n";
-		f << "\n";
-		f << "namespace " << design_ns << " {\n";
-		f << "\n";
-		for (auto module : modules) {
-			if (!split_intf)
-				dump_module_intf(module);
-			dump_module_impl(module);
-		}
-		f << "} // namespace " << design_ns << "\n";
-		f << "\n";
-		if (top_module != nullptr && debug_info) {
-			f << "cxxrtl_toplevel " << design_ns << "_create() {\n";
-			inc_indent();
-				f << indent << "return new _cxxrtl_toplevel { ";
-				f << "std::make_unique<" << design_ns << "::" << mangle(top_module) << ">()";
-				f << " };\n";
-			dec_indent();
-			f << "}\n";
-		}
-
-		*impl_f << f.str(); f.str("");
-	}
-
-	// Edge-type sync rules require us to emit edge detectors, which require coordination between
-	// eval and commit phases. To do this we need to collect them upfront.
-	//
-	// Note that the simulator commit phase operates at wire granularity but edge-type sync rules
-	// operate at wire bit granularity; it is possible to have code similar to:
-	//     wire [3:0] clocks;
-	//     always @(posedge clocks[0]) ...
-	// To handle this we track edge sensitivity both for wires and wire bits.
-	void register_edge_signal(SigMap &sigmap, RTLIL::SigSpec signal, RTLIL::SyncType type)
-	{
-		signal = sigmap(signal);
-		log_assert(signal.is_wire() && signal.is_bit());
-		log_assert(type == RTLIL::STp || type == RTLIL::STn || type == RTLIL::STe);
-
-		RTLIL::SigBit sigbit = signal[0];
-		if (!edge_types.count(sigbit))
-			edge_types[sigbit] = type;
-		else if (edge_types[sigbit] != type)
-			edge_types[sigbit] = RTLIL::STe;
-		edge_wires.insert(signal.as_wire());
-	}
-
-	void analyze_design(RTLIL::Design *design)
-	{
-		bool has_feedback_arcs = false;
-		bool has_buffered_wires = false;
-
-		for (auto module : design->modules()) {
-			if (!design->selected_module(module))
-				continue;
-
-			SigMap &sigmap = sigmaps[module];
-			sigmap.set(module);
-
-			if (module->get_bool_attribute(ID(cxxrtl_blackbox))) {
-				for (auto port : module->ports) {
-					RTLIL::Wire *wire = module->wire(port);
-					if (wire->has_attribute(ID(cxxrtl_edge))) {
-						RTLIL::Const edge_attr = wire->attributes[ID(cxxrtl_edge)];
-						if (!(edge_attr.flags & RTLIL::CONST_FLAG_STRING) || (int)edge_attr.decode_string().size() != GetSize(wire))
-							log_cmd_error("Attribute `cxxrtl_edge' of port `%s.%s' is not a string with one character per bit.\n",
-							              log_id(module), log_signal(wire));
-
-						std::string edges = wire->get_string_attribute(ID(cxxrtl_edge));
-						for (int i = 0; i < GetSize(wire); i++) {
-							RTLIL::SigSpec wire_sig = wire;
-							switch (edges[i]) {
-								case '-': break;
-								case 'p': register_edge_signal(sigmap, wire_sig[i], RTLIL::STp); break;
-								case 'n': register_edge_signal(sigmap, wire_sig[i], RTLIL::STn); break;
-								case 'a': register_edge_signal(sigmap, wire_sig[i], RTLIL::STe); break;
-								default:
-									log_cmd_error("Attribute `cxxrtl_edge' of port `%s.%s' contains specifiers "
-									              "other than '-', 'p', 'n', or 'a'.\n",
-										log_id(module), log_signal(wire));
-							}
-						}
-					}
-				}
-
-				// Black boxes converge by default, since their implementations are quite unlikely to require
-				// internal propagation of comb signals.
-				eval_converges[module] = true;
-				continue;
-			}
-
-			FlowGraph flow;
-
-			for (auto conn : module->connections())
-				flow.add_node(conn);
-
-			dict<const RTLIL::Cell*, FlowGraph::Node*> memrw_cell_nodes;
-			dict<std::pair<RTLIL::SigBit, const RTLIL::Memory*>,
-			     pool<const RTLIL::Cell*>> memwr_per_domain;
-			for (auto cell : module->cells()) {
-				if (!cell->known())
-					log_cmd_error("Unknown cell `%s'.\n", log_id(cell->type));
-
-				RTLIL::Module *cell_module = design->module(cell->type);
-				if (cell_module &&
-				    cell_module->get_blackbox_attribute() &&
-				    !cell_module->get_bool_attribute(ID(cxxrtl_blackbox)))
-					log_cmd_error("External blackbox cell `%s' is not marked as a CXXRTL blackbox.\n", log_id(cell->type));
-
-				if (cell_module &&
-				    cell_module->get_bool_attribute(ID(cxxrtl_blackbox)) &&
-				    cell_module->get_bool_attribute(ID(cxxrtl_template)))
-					blackbox_specializations[cell_module].insert(template_args(cell));
-
-				FlowGraph::Node *node = flow.add_node(cell);
-
-				// Various DFF cells are treated like posedge/negedge processes, see above for details.
-				if (cell->type.in(ID($dff), ID($dffe), ID($adff), ID($dffsr))) {
-					if (cell->getPort(ID::CLK).is_wire())
-						register_edge_signal(sigmap, cell->getPort(ID::CLK),
-							cell->parameters[ID::CLK_POLARITY].as_bool() ? RTLIL::STp : RTLIL::STn);
-				}
-				// Similar for memory port cells.
-				if (cell->type.in(ID($memrd), ID($memwr))) {
-					if (cell->getParam(ID::CLK_ENABLE).as_bool()) {
-						if (cell->getPort(ID::CLK).is_wire())
-							register_edge_signal(sigmap, cell->getPort(ID::CLK),
-								cell->parameters[ID::CLK_POLARITY].as_bool() ? RTLIL::STp : RTLIL::STn);
-					}
-					memrw_cell_nodes[cell] = node;
-				}
-				// Optimize access to read-only memories.
-				if (cell->type == ID($memwr))
-					writable_memories.insert(module->memories[cell->getParam(ID::MEMID).decode_string()]);
-				// Collect groups of memory write ports in the same domain.
-				if (cell->type == ID($memwr) && cell->getParam(ID::CLK_ENABLE).as_bool() && cell->getPort(ID::CLK).is_wire()) {
-					RTLIL::SigBit clk_bit = sigmap(cell->getPort(ID::CLK))[0];
-					const RTLIL::Memory *memory = module->memories[cell->getParam(ID::MEMID).decode_string()];
-					memwr_per_domain[{clk_bit, memory}].insert(cell);
-				}
-				// Handling of packed memories is delegated to the `memory_unpack` pass, so we can rely on the presence
-				// of RTLIL memory objects and $memrd/$memwr/$meminit cells.
-				if (cell->type.in(ID($mem)))
-					log_assert(false);
-			}
-			for (auto cell : module->cells()) {
-				// Collect groups of memory write ports read by every transparent read port.
-				if (cell->type == ID($memrd) && cell->getParam(ID::CLK_ENABLE).as_bool() && cell->getPort(ID::CLK).is_wire() &&
-				    cell->getParam(ID::TRANSPARENT).as_bool()) {
-					RTLIL::SigBit clk_bit = sigmap(cell->getPort(ID::CLK))[0];
-					const RTLIL::Memory *memory = module->memories[cell->getParam(ID::MEMID).decode_string()];
-					for (auto memwr_cell : memwr_per_domain[{clk_bit, memory}]) {
-						transparent_for[cell].insert(memwr_cell);
-						// Our implementation of transparent $memrd cells reads \EN, \ADDR and \DATA from every $memwr cell
-						// in the same domain, which isn't directly visible in the netlist. Add these uses explicitly.
-						flow.add_uses(memrw_cell_nodes[cell], memwr_cell->getPort(ID::EN));
-						flow.add_uses(memrw_cell_nodes[cell], memwr_cell->getPort(ID::ADDR));
-						flow.add_uses(memrw_cell_nodes[cell], memwr_cell->getPort(ID::DATA));
-					}
-				}
-			}
-
-			for (auto proc : module->processes) {
-				flow.add_node(proc.second);
-
-				for (auto sync : proc.second->syncs)
-					switch (sync->type) {
-						// Edge-type sync rules require pre-registration.
-						case RTLIL::STp:
-						case RTLIL::STn:
-						case RTLIL::STe:
-							register_edge_signal(sigmap, sync->signal, sync->type);
-							break;
-
-						// Level-type sync rules require no special handling.
-						case RTLIL::ST0:
-						case RTLIL::ST1:
-						case RTLIL::STa:
-							break;
-
-						case RTLIL::STg:
-							log_cmd_error("Global clock is not supported.\n");
-
-						// Handling of init-type sync rules is delegated to the `proc_init` pass, so we can use the wire
-						// attribute regardless of input.
-						case RTLIL::STi:
-							log_assert(false);
-					}
-			}
-
-			for (auto wire : module->wires()) {
-				if (!flow.is_elidable(wire)) continue;
-				if (wire->port_id != 0) continue;
-				if (wire->get_bool_attribute(ID::keep)) continue;
-				if (wire->name.begins_with("$") && !elide_internal) continue;
-				if (wire->name.begins_with("\\") && !elide_public) continue;
-				if (edge_wires[wire]) continue;
-				log_assert(flow.wire_comb_defs[wire].size() == 1);
-				elided_wires[wire] = **flow.wire_comb_defs[wire].begin();
-			}
-
-			dict<FlowGraph::Node*, pool<const RTLIL::Wire*>, hash_ptr_ops> node_defs;
-			for (auto wire_comb_def : flow.wire_comb_defs)
-				for (auto node : wire_comb_def.second)
-					node_defs[node].insert(wire_comb_def.first);
-
-			Scheduler<FlowGraph::Node> scheduler;
-			dict<FlowGraph::Node*, Scheduler<FlowGraph::Node>::Vertex*, hash_ptr_ops> node_map;
-			for (auto node : flow.nodes)
-				node_map[node] = scheduler.add(node);
-			for (auto node_def : node_defs) {
-				auto vertex = node_map[node_def.first];
-				for (auto wire : node_def.second)
-					for (auto succ_node : flow.wire_uses[wire]) {
-						auto succ_vertex = node_map[succ_node];
-						vertex->succs.insert(succ_vertex);
-						succ_vertex->preds.insert(vertex);
-					}
-			}
-
-			auto eval_order = scheduler.schedule();
-			pool<FlowGraph::Node*, hash_ptr_ops> evaluated;
-			pool<const RTLIL::Wire*> feedback_wires;
-			for (auto vertex : eval_order) {
-				auto node = vertex->data;
-				schedule[module].push_back(*node);
-				// Any wire that is an output of node vo and input of node vi where vo is scheduled later than vi
-				// is a feedback wire. Feedback wires indicate apparent logic loops in the design, which may be
-				// caused by a true logic loop, but usually are a benign result of dependency tracking that works
-				// on wire, not bit, level. Nevertheless, feedback wires cannot be localized.
-				evaluated.insert(node);
-				for (auto wire : node_defs[node])
-					for (auto succ_node : flow.wire_uses[wire])
-						if (evaluated[succ_node]) {
-							feedback_wires.insert(wire);
-							// Feedback wires may never be elided because feedback requires state, but the point of elision
-							// (and localization) is to eliminate state.
-							elided_wires.erase(wire);
-						}
-			}
-
-			if (!feedback_wires.empty()) {
-				has_feedback_arcs = true;
-				log("Module `%s' contains feedback arcs through wires:\n", log_id(module));
-				for (auto wire : feedback_wires)
-					log("  %s\n", log_id(wire));
-				log("\n");
-			}
-
-			for (auto wire : module->wires()) {
-				if (feedback_wires[wire]) continue;
-				if (wire->port_id != 0) continue;
-				if (wire->get_bool_attribute(ID::keep)) continue;
-				if (wire->name.begins_with("$") && !localize_internal) continue;
-				if (wire->name.begins_with("\\") && !localize_public) continue;
-				if (edge_wires[wire]) continue;
-				if (flow.wire_sync_defs.count(wire) > 0) continue;
-				localized_wires.insert(wire);
-			}
-
-			// For maximum performance, the state of the simulation (which is the same as the set of its double buffered
-			// wires, since using a singly buffered wire for any kind of state introduces a race condition) should contain
-			// no wires attached to combinatorial outputs. Feedback wires, by definition, make that impossible. However,
-			// it is possible that a design with no feedback arcs would end up with doubly buffered wires in such cases
-			// as a wire with multiple drivers where one of them is combinatorial and the other is synchronous. Such designs
-			// also require more than one delta cycle to converge.
-			pool<const RTLIL::Wire*> buffered_wires;
-			for (auto wire : module->wires()) {
-				if (flow.wire_comb_defs[wire].size() > 0 && !elided_wires.count(wire) && !localized_wires[wire]) {
-					if (!feedback_wires[wire])
-						buffered_wires.insert(wire);
-				}
-			}
-			if (!buffered_wires.empty()) {
-				has_buffered_wires = true;
-				log("Module `%s' contains buffered combinatorial wires:\n", log_id(module));
-				for (auto wire : buffered_wires)
-					log("  %s\n", log_id(wire));
-				log("\n");
-			}
-
-			eval_converges[module] = feedback_wires.empty() && buffered_wires.empty();
-		}
-		if (has_feedback_arcs || has_buffered_wires) {
-			// Although both non-feedback buffered combinatorial wires and apparent feedback wires may be eliminated
-			// by optimizing the design, if after `proc; flatten` there are any feedback wires remaining, it is very
-			// likely that these feedback wires are indicative of a true logic loop, so they get emphasized in the message.
-			const char *why_pessimistic = nullptr;
-			if (has_feedback_arcs)
-				why_pessimistic = "feedback wires";
-			else if (has_buffered_wires)
-				why_pessimistic = "buffered combinatorial wires";
-			log_warning("Design contains %s, which require delta cycles during evaluation.\n", why_pessimistic);
-			if (!max_opt_level)
-				log("Increasing the optimization level may eliminate %s from the design.\n", why_pessimistic);
-		}
-	}
-
-	void check_design(RTLIL::Design *design, bool &has_sync_init, bool &has_packed_mem)
-	{
-		has_sync_init = has_packed_mem = false;
-
-		for (auto module : design->modules()) {
-			if (module->get_blackbox_attribute() && !module->has_attribute(ID(cxxrtl_blackbox)))
-				continue;
-
-			if (!design->selected_whole_module(module))
-				if (design->selected_module(module))
-					log_cmd_error("Can't handle partially selected module `%s'!\n", id2cstr(module->name));
-			if (!design->selected_module(module))
-				continue;
-
-			for (auto proc : module->processes)
-				for (auto sync : proc.second->syncs)
-					if (sync->type == RTLIL::STi)
-						has_sync_init = true;
-
-			for (auto cell : module->cells())
-				if (cell->type == ID($mem))
-					has_packed_mem = true;
-		}
-	}
-
-	void prepare_design(RTLIL::Design *design)
-	{
-		bool did_anything = false;
-		bool has_sync_init, has_packed_mem;
-		log_push();
-		check_design(design, has_sync_init, has_packed_mem);
-		if (run_proc_flatten) {
-			Pass::call(design, "proc");
-			Pass::call(design, "flatten");
-			did_anything = true;
-		} else if (has_sync_init) {
-			// We're only interested in proc_init, but it depends on proc_prune and proc_clean, so call those
-			// in case they weren't already. (This allows `yosys foo.v -o foo.cc` to work.)
-			Pass::call(design, "proc_prune");
-			Pass::call(design, "proc_clean");
-			Pass::call(design, "proc_init");
-			did_anything = true;
-		}
-		if (has_packed_mem) {
-			Pass::call(design, "memory_unpack");
-			did_anything = true;
-		}
-		// Recheck the design if it was modified.
-		if (has_sync_init || has_packed_mem)
-			check_design(design, has_sync_init, has_packed_mem);
-		log_assert(!(has_sync_init || has_packed_mem));
-		log_pop();
-		if (did_anything)
-			log_spacer();
-		analyze_design(design);
-	}
-};
-
-struct CxxrtlBackend : public Backend {
-	static const int DEFAULT_OPT_LEVEL = 5;
-	static const int DEFAULT_DEBUG_LEVEL = 1;
-
-	CxxrtlBackend() : Backend("cxxrtl", "convert design to C++ RTL simulation") { }
-	void help() YS_OVERRIDE
-	{
-		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
-		log("\n");
-		log("    write_cxxrtl [options] [filename]\n");
-		log("\n");
-		log("Write C++ code that simulates the design. The generated code requires a driver\n");
-		log("that instantiates the design, toggles its clock, and interacts with its ports.\n");
-		log("\n");
-		log("The following driver may be used as an example for a design with a single clock\n");
-		log("driving rising edge triggered flip-flops:\n");
-		log("\n");
-		log("    #include \"top.cc\"\n");
-		log("\n");
-		log("    int main() {\n");
-		log("      cxxrtl_design::p_top top;\n");
-		log("      top.step();\n");
-		log("      while (1) {\n");
-		log("        /* user logic */\n");
-		log("        top.p_clk = value<1> {0u};\n");
-		log("        top.step();\n");
-		log("        top.p_clk = value<1> {1u};\n");
-		log("        top.step();\n");
-		log("      }\n");
-		log("    }\n");
-		log("\n");
-		log("Note that CXXRTL simulations, just like the hardware they are simulating, are\n");
-		log("subject to race conditions. If, in the example above, the user logic would run\n");
-		log("simultaneously with the rising edge of the clock, the design would malfunction.\n");
-		log("\n");
-		log("This backend supports replacing parts of the design with black boxes implemented\n");
-		log("in C++. If a module marked as a CXXRTL black box, its implementation is ignored,\n");
-		log("and the generated code consists only of an interface and a factory function.\n");
-		log("The driver must implement the factory function that creates an implementation of\n");
-		log("the black box, taking into account the parameters it is instantiated with.\n");
-		log("\n");
-		log("For example, the following Verilog code defines a CXXRTL black box interface for\n");
-		log("a synchronous debug sink:\n");
-		log("\n");
-		log("    (* cxxrtl_blackbox *)\n");
-		log("    module debug(...);\n");
-		log("      (* cxxrtl_edge = \"p\" *) input clk;\n");
-		log("      input en;\n");
-		log("      input [7:0] i_data;\n");
-		log("      (* cxxrtl_sync *) output [7:0] o_data;\n");
-		log("    endmodule\n");
-		log("\n");
-		log("For this HDL interface, this backend will generate the following C++ interface:\n");
-		log("\n");
-		log("    struct bb_p_debug : public module {\n");
-		log("      value<1> p_clk;\n");
-		log("      bool posedge_p_clk() const { /* ... */ }\n");
-		log("      value<1> p_en;\n");
-		log("      value<8> p_i_data;\n");
-		log("      wire<8> p_o_data;\n");
-		log("\n");
-		log("      bool eval() override;\n");
-		log("      bool commit() override;\n");
-		log("\n");
-		log("      static std::unique_ptr<bb_p_debug>\n");
-		log("      create(std::string name, metadata_map parameters, metadata_map attributes);\n");
-		log("    };\n");
-		log("\n");
-		log("The `create' function must be implemented by the driver. For example, it could\n");
-		log("always provide an implementation logging the values to standard error stream:\n");
-		log("\n");
-		log("    namespace cxxrtl_design {\n");
-		log("\n");
-		log("    struct stderr_debug : public bb_p_debug {\n");
-		log("      bool eval() override {\n");
-		log("        if (posedge_p_clk() && p_en)\n");
-		log("          fprintf(stderr, \"debug: %%02x\\n\", p_i_data.data[0]);\n");
-		log("        p_o_data.next = p_i_data;\n");
-		log("        return bb_p_debug::eval();\n");
-		log("      }\n");
-		log("    };\n");
-		log("\n");
-		log("    std::unique_ptr<bb_p_debug>\n");
-		log("    bb_p_debug::create(std::string name, cxxrtl::metadata_map parameters,\n");
-		log("                       cxxrtl::metadata_map attributes) {\n");
-		log("      return std::make_unique<stderr_debug>();\n");
-		log("    }\n");
-		log("\n");
-		log("    }\n");
-		log("\n");
-		log("For complex applications of black boxes, it is possible to parameterize their\n");
-		log("port widths. For example, the following Verilog code defines a CXXRTL black box\n");
-		log("interface for a configurable width debug sink:\n");
-		log("\n");
-		log("    (* cxxrtl_blackbox, cxxrtl_template = \"WIDTH\" *)\n");
-		log("    module debug(...);\n");
-		log("      parameter WIDTH = 8;\n");
-		log("      (* cxxrtl_edge = \"p\" *) input clk;\n");
-		log("      input en;\n");
-		log("      (* cxxrtl_width = \"WIDTH\" *) input [WIDTH - 1:0] i_data;\n");
-		log("      (* cxxrtl_width = \"WIDTH\" *) output [WIDTH - 1:0] o_data;\n");
-		log("    endmodule\n");
-		log("\n");
-		log("For this parametric HDL interface, this backend will generate the following C++\n");
-		log("interface (only the differences are shown):\n");
-		log("\n");
-		log("    template<size_t WIDTH>\n");
-		log("    struct bb_p_debug : public module {\n");
-		log("      // ...\n");
-		log("      value<WIDTH> p_i_data;\n");
-		log("      wire<WIDTH> p_o_data;\n");
-		log("      // ...\n");
-		log("      static std::unique_ptr<bb_p_debug<WIDTH>>\n");
-		log("      create(std::string name, metadata_map parameters, metadata_map attributes);\n");
-		log("    };\n");
-		log("\n");
-		log("The `create' function must be implemented by the driver, specialized for every\n");
-		log("possible combination of template parameters. (Specialization is necessary to\n");
-		log("enable separate compilation of generated code and black box implementations.)\n");
-		log("\n");
-		log("    template<size_t SIZE>\n");
-		log("    struct stderr_debug : public bb_p_debug<SIZE> {\n");
-		log("      // ...\n");
-		log("    };\n");
-		log("\n");
-		log("    template<>\n");
-		log("    std::unique_ptr<bb_p_debug<8>>\n");
-		log("    bb_p_debug<8>::create(std::string name, cxxrtl::metadata_map parameters,\n");
-		log("                          cxxrtl::metadata_map attributes) {\n");
-		log("      return std::make_unique<stderr_debug<8>>();\n");
-		log("    }\n");
-		log("\n");
-		log("The following attributes are recognized by this backend:\n");
-		log("\n");
-		log("    cxxrtl_blackbox\n");
-		log("        only valid on modules. if specified, the module contents are ignored,\n");
-		log("        and the generated code includes only the module interface and a factory\n");
-		log("        function, which will be called to instantiate the module.\n");
-		log("\n");
-		log("    cxxrtl_edge\n");
-		log("        only valid on inputs of black boxes. must be one of \"p\", \"n\", \"a\".\n");
-		log("        if specified on signal `clk`, the generated code includes edge detectors\n");
-		log("        `posedge_p_clk()` (if \"p\"), `negedge_p_clk()` (if \"n\"), or both (if\n");
-		log("        \"a\"), simplifying implementation of clocked black boxes.\n");
-		log("\n");
-		log("    cxxrtl_template\n");
-		log("        only valid on black boxes. must contain a space separated sequence of\n");
-		log("        identifiers that have a corresponding black box parameters. for each\n");
-		log("        of them, the generated code includes a `size_t` template parameter.\n");
-		log("\n");
-		log("    cxxrtl_width\n");
-		log("        only valid on ports of black boxes. must be a constant expression, which\n");
-		log("        is directly inserted into generated code.\n");
-		log("\n");
-		log("    cxxrtl_comb, cxxrtl_sync\n");
-		log("        only valid on outputs of black boxes. if specified, indicates that every\n");
-		log("        bit of the output port is driven, correspondingly, by combinatorial or\n");
-		log("        synchronous logic. this knowledge is used for scheduling optimizations.\n");
-		log("        if neither is specified, the output will be pessimistically treated as\n");
-		log("        driven by both combinatorial and synchronous logic.\n");
-		log("\n");
-		log("The following options are supported by this backend:\n");
-		log("\n");
-		log("    -header\n");
-		log("        generate separate interface (.h) and implementation (.cc) files.\n");
-		log("        if specified, the backend must be called with a filename, and filename\n");
-		log("        of the interface is derived from filename of the implementation.\n");
-		log("        otherwise, interface and implementation are generated together.\n");
-		log("\n");
-		log("    -namespace <ns-name>\n");
-		log("        place the generated code into namespace <ns-name>. if not specified,\n");
-		log("        \"cxxrtl_design\" is used.\n");
-		log("\n");
-		log("    -O <level>\n");
-		log("        set the optimization level. the default is -O%d. higher optimization\n", DEFAULT_OPT_LEVEL);
-		log("        levels dramatically decrease compile and run time, and highest level\n");
-		log("        possible for a design should be used.\n");
-		log("\n");
-		log("    -O0\n");
-		log("        no optimization.\n");
-		log("\n");
-		log("    -O1\n");
-		log("        elide internal wires if possible.\n");
-		log("\n");
-		log("    -O2\n");
-		log("        like -O1, and localize internal wires if possible.\n");
-		log("\n");
-		log("    -O3\n");
-		log("        like -O2, and elide public wires not marked (*keep*) if possible.\n");
-		log("\n");
-		log("    -O4\n");
-		log("        like -O3, and localize public wires not marked (*keep*) if possible.\n");
-		log("\n");
-		log("    -O5\n");
-		log("        like -O4, and run `proc; flatten` first.\n");
-		log("\n");
-		log("    -g <level>\n");
-		log("        set the debug level. the default is -g%d. higher debug levels provide\n", DEFAULT_DEBUG_LEVEL);
-		log("        more visibility and generate more code, but do not pessimize evaluation.\n");
-		log("\n");
-		log("    -g0\n");
-		log("        no debug information.\n");
-		log("\n");
-		log("    -g1\n");
-		log("        debug information for non-localized public wires.\n");
-		log("\n");
-	}
-
-	void execute(std::ostream *&f, std::string filename, std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
-	{
-		int opt_level = DEFAULT_OPT_LEVEL;
-		int debug_level = DEFAULT_DEBUG_LEVEL;
-		CxxrtlWorker worker;
-
-		log_header(design, "Executing CXXRTL backend.\n");
-
-		size_t argidx;
-		for (argidx = 1; argidx < args.size(); argidx++)
-		{
-			if (args[argidx] == "-O" && argidx+1 < args.size()) {
-				opt_level = std::stoi(args[++argidx]);
-				continue;
-			}
-			if (args[argidx].substr(0, 2) == "-O" && args[argidx].size() == 3 && isdigit(args[argidx][2])) {
-				opt_level = std::stoi(args[argidx].substr(2));
-				continue;
-			}
-			if (args[argidx] == "-g" && argidx+1 < args.size()) {
-				debug_level = std::stoi(args[++argidx]);
-				continue;
-			}
-			if (args[argidx].substr(0, 2) == "-g" && args[argidx].size() == 3 && isdigit(args[argidx][2])) {
-				debug_level = std::stoi(args[argidx].substr(2));
-				continue;
-			}
-			if (args[argidx] == "-header") {
-				worker.split_intf = true;
-				continue;
-			}
-			if (args[argidx] == "-namespace" && argidx+1 < args.size()) {
-				worker.design_ns = args[++argidx];
-				continue;
-			}
-			break;
-		}
-		extra_args(f, filename, args, argidx);
-
-		switch (opt_level) {
-			// the highest level here must match DEFAULT_OPT_LEVEL
-			case 5:
-				worker.max_opt_level = true;
-				worker.run_proc_flatten = true;
-				YS_FALLTHROUGH
-			case 4:
-				worker.localize_public = true;
-				YS_FALLTHROUGH
-			case 3:
-				worker.elide_public = true;
-				YS_FALLTHROUGH
-			case 2:
-				worker.localize_internal = true;
-				YS_FALLTHROUGH
-			case 1:
-				worker.elide_internal = true;
-				YS_FALLTHROUGH
-			case 0:
-				break;
-			default:
-				log_cmd_error("Invalid optimization level %d.\n", opt_level);
-		}
-
-		switch (debug_level) {
-			// the highest level here must match DEFAULT_DEBUG_LEVEL
-			case 1:
-				worker.debug_info = true;
-				YS_FALLTHROUGH
-			case 0:
-				break;
-			default:
-				log_cmd_error("Invalid optimization level %d.\n", opt_level);
-		}
-
-		std::ofstream intf_f;
-		if (worker.split_intf) {
-			if (filename == "<stdout>")
-				log_cmd_error("Option -header must be used with a filename.\n");
-
-			worker.intf_filename = filename.substr(0, filename.rfind('.')) + ".h";
-			intf_f.open(worker.intf_filename, std::ofstream::trunc);
-			if (intf_f.fail())
-				log_cmd_error("Can't open file `%s' for writing: %s\n",
-				              worker.intf_filename.c_str(), strerror(errno));
-
-			worker.intf_f = &intf_f;
-		}
-		worker.impl_f = f;
-
-		worker.prepare_design(design);
-		worker.dump_design(design);
-	}
-} CxxrtlBackend;
-
-PRIVATE_NAMESPACE_END