diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index 1bcff2772..776ea4d40 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -3517,10 +3517,19 @@ void RTLIL::Module::remove(const pool<RTLIL::Wire*> &wires)
 		}
 	};
 
-	DeleteWireWorker delete_wire_worker;
-	delete_wire_worker.module = this;
-	delete_wire_worker.wires_p = &wires;
-	rewrite_sigspecs2(delete_wire_worker);
+	if (sig_norm_index != nullptr) {
+		for (auto wire : wires) {
+			log_assert(wire->driverCell_ == nullptr);
+			for (int i = 0; i < GetSize(wire); i++)
+				log_assert(fanout(SigBit(wire, i)).empty());
+		}
+		log_assert(processes.empty());
+	} else {
+		DeleteWireWorker delete_wire_worker;
+		delete_wire_worker.module = this;
+		delete_wire_worker.wires_p = &wires;
+		rewrite_sigspecs2(delete_wire_worker);
+	}
 
 	if (design->flagBufferedNormalized) {
 		for (auto wire : wires) {
diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index 992839f85..f8fae82f3 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -3083,6 +3083,8 @@ public:
 
 	const SigMap *signorm_sigmap();
 
+	void signorm_compact(const pool<RTLIL::Wire *> &dead_wires);
+
 	// Equivalent to `connect(lhs, rhs)` followed by `sigNormalize()` for the
 	// merge implied by this single connection: updates the sigmap, promotes
 	// the driven side as canonical, and re-normalizes any existing fanout
diff --git a/kernel/rtlil_bufnorm.cc b/kernel/rtlil_bufnorm.cc
index 68395727a..e111a80a3 100644
--- a/kernel/rtlil_bufnorm.cc
+++ b/kernel/rtlil_bufnorm.cc
@@ -279,6 +279,23 @@ struct RTLIL::SigNormIndex
 		++signorm_restore_count;
 	}
 
+	void compact(const pool<Wire *> &dead_wires) {
+		flush_connections();
+		log_assert(newly_driven.empty());
+
+		SigMap fresh;
+		for (auto const &bit : sigmap.database) {
+			if (bit.is_wire() && dead_wires.count(bit.wire))
+				continue;
+			SigBit rep = sigmap(bit);
+			if (rep == bit)
+				continue;
+			log_assert(!(rep.is_wire() && dead_wires.count(rep.wire)));
+			fresh.add(bit, rep);
+		}
+
+		sigmap.swap(fresh);
+	}
 };
 
 
@@ -429,7 +446,7 @@ const SigMap *RTLIL::Module::signorm_sigmap()
 		return nullptr;
 
 	int64_t start = PerformanceTimer::query();
-	sig_norm_index->flush_connections();
+	sig_norm_index->normalize();
 	int64_t time_ns = PerformanceTimer::query() - start;
 	Pass::subtract_from_current_runtime_ns(time_ns);
 	signorm_restore_ns += time_ns;
@@ -438,6 +455,13 @@ const SigMap *RTLIL::Module::signorm_sigmap()
 	return &sig_norm_index->sigmap;
 }
 
+void RTLIL::Module::signorm_compact(const pool<RTLIL::Wire *> &dead_wires)
+{
+	if (sig_norm_index == nullptr)
+		return;
+	sig_norm_index->compact(dead_wires);
+}
+
 void RTLIL::Module::new_connections(const std::vector<RTLIL::SigSig> &new_conn)
 {
 	if (sig_norm_index != nullptr) {
diff --git a/passes/opt/opt_clean/CMakeLists.txt b/passes/opt/opt_clean/CMakeLists.txt
index 70b137c93..f2aac3b6d 100644
--- a/passes/opt/opt_clean/CMakeLists.txt
+++ b/passes/opt/opt_clean/CMakeLists.txt
@@ -2,6 +2,7 @@ yosys_pass(opt_clean
 	cells_all.cc
 	cells_temp.cc
 	wires.cc
+	signorm.cc
 	inits.cc
 	opt_clean.cc
 	opt_clean.h
diff --git a/passes/opt/opt_clean/opt_clean.cc b/passes/opt/opt_clean/opt_clean.cc
index da07d396c..f5d1c4a39 100644
--- a/passes/opt/opt_clean/opt_clean.cc
+++ b/passes/opt/opt_clean/opt_clean.cc
@@ -34,6 +34,12 @@ void rmunused_module(RTLIL::Module *module, bool rminit, CleanRunContext &clean_
 	// we only start multithreading with at least 2000 cells.
 	int num_worker_threads = ThreadPool::work_pool_size(0, module->cells_size(), 10000);
 	ParallelDispatchThreadPool::Subpool subpool(clean_ctx.thread_pool, num_worker_threads);
+
+	if (module->signorm_sigmap() != nullptr) {
+		rmunused_module_signorm(module, subpool, clean_ctx);
+		return;
+	}
+
 	remove_temporary_cells(module, subpool, clean_ctx.flags.verbose);
 	rmunused_module_cells(module, subpool, clean_ctx);
 	while (rmunused_module_signals(module, subpool, clean_ctx)) { }
@@ -84,8 +90,6 @@ struct OptCleanPass : public Pass {
 		}
 		extra_args(args, argidx, design);
 
-		design->sigNormalize(false);
-
 		{
 			std::vector<RTLIL::Module*> selected_modules;
 			for (auto module : design->selected_whole_modules_warn())
@@ -143,8 +147,6 @@ struct CleanPass : public Pass {
 		}
 		extra_args(args, argidx, design);
 
-		design->sigNormalize(false);
-
 		{
 			std::vector<RTLIL::Module*> selected_modules;
 			for (auto module : design->selected_unboxed_whole_modules())
diff --git a/passes/opt/opt_clean/opt_clean.h b/passes/opt/opt_clean/opt_clean.h
index c48a8188a..ba5a8ad69 100644
--- a/passes/opt/opt_clean/opt_clean.h
+++ b/passes/opt/opt_clean/opt_clean.h
@@ -82,6 +82,10 @@ public:
 	}
 };
 
+bool check_public_name(const std::string &id_str);
+
+void rmunused_module_signorm(RTLIL::Module *module, ParallelDispatchThreadPool::Subpool &subpool, CleanRunContext &clean_ctx);
+
 void remove_temporary_cells(RTLIL::Module *module, ParallelDispatchThreadPool::Subpool &subpool, bool verbose);
 void rmunused_module_cells(Module *module, ParallelDispatchThreadPool::Subpool &subpool, CleanRunContext &clean_ctx);
 bool rmunused_module_signals(RTLIL::Module *module, ParallelDispatchThreadPool::Subpool &subpool, CleanRunContext &clean_ctx);
diff --git a/passes/opt/opt_clean/signorm.cc b/passes/opt/opt_clean/signorm.cc
new file mode 100644
index 000000000..e3b34411d
--- /dev/null
+++ b/passes/opt/opt_clean/signorm.cc
@@ -0,0 +1,398 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Claire Xenia Wolf <claire@yosyshq.com>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#include "kernel/ffinit.h"
+#include "kernel/yosys_common.h"
+#include "passes/opt/opt_clean/opt_clean.h"
+
+USING_YOSYS_NAMESPACE
+PRIVATE_NAMESPACE_BEGIN
+
+bool is_signed_pos(RTLIL::Cell *cell) {
+	return cell->type == TW($pos) && cell->getParam(ID::A_SIGNED).as_bool();
+}
+
+bool remove_buffer_cells(RTLIL::Module *module, bool verbose)
+{
+	std::vector<RTLIL::Cell *> buffers;
+	for (int i = 0; i < module->cells_size(); i++) {
+		RTLIL::Cell *cell = module->cell_at(i);
+		if (cell->type.in(TW($pos), TW($_BUF_), TW($buf)) && !cell->has_keep_attr())
+			buffers.push_back(cell);
+	}
+
+	bool did_something = false;
+	for (RTLIL::Cell *cell : buffers) {
+		RTLIL::SigSpec a = cell->getPort(TW::A);
+		RTLIL::SigSpec y = cell->getPort(TW::Y);
+		a.extend_u0(GetSize(y), is_signed_pos(cell));
+
+		if (a.has_const(State::Sz)) {
+			RTLIL::SigSpec new_a, new_y;
+			bool bail = false;
+			for (int i = 0; i < GetSize(a); ++i) {
+				if (a[i] == State::Sz) {
+					bail = true;
+					break;
+				}
+				new_a.append(a[i]);
+				new_y.append(y[i]);
+			}
+			if (bail)
+				continue;
+			a = std::move(new_a);
+			y = std::move(new_y);
+		}
+
+		if (verbose)
+			log_debug("  removing buffer cell `%s': %s = %s\n", cell->name,
+					log_signal(y), log_signal(a));
+
+		module->remove(cell);
+		if (!y.empty())
+			module->connect_incremental(y, a);
+		did_something = true;
+	}
+	return did_something;
+}
+
+struct LiveSet {
+	pool<RTLIL::Cell *> cells;
+	std::vector<RTLIL::Cell *> worklist;
+
+	void mark(RTLIL::Cell *cell) {
+		if (cell != nullptr && cells.insert(cell).second)
+			worklist.push_back(cell);
+	}
+};
+
+dict<RTLIL::SigBit, std::vector<RTLIL::Cell *>> index_connect_cells(RTLIL::Module *module)
+{
+	dict<RTLIL::SigBit, std::vector<RTLIL::Cell *>> result;
+	for (int i = 0; i < module->cells_size(); i++) {
+		RTLIL::Cell *cell = module->cell_at(i);
+		if (cell->type != TW($connect))
+			continue;
+		for (auto &[port, sig] : cell->connections())
+			for (auto bit : sig)
+				if (bit.is_wire())
+					result[bit].push_back(cell);
+	}
+	return result;
+}
+
+void trace_live(RTLIL::Module *module, LiveSet &live, pool<std::string> &live_mems,
+		const SigMap &sigmap, CleanRunContext &clean_ctx)
+{
+	dict<RTLIL::SigBit, std::vector<RTLIL::Cell *>> connect_cells = index_connect_cells(module);
+	dict<std::string, std::vector<RTLIL::Cell *>> mem_writers;
+
+	for (int i = 0; i < module->cells_size(); i++) {
+		RTLIL::Cell *cell = module->cell_at(i);
+		if (cell->type.in(TW($memwr), TW($memwr_v2), TW($meminit), TW($meminit_v2)))
+			mem_writers[cell->getParam(ID::MEMID).decode_string()].push_back(cell);
+		if (cell->type == TW($input_port) || clean_ctx.keep_cache.query(cell))
+			live.mark(cell);
+	}
+
+	for (int i = 0; i < module->wires_size(); i++) {
+		RTLIL::Wire *wire = module->wire_at(i);
+		if (!wire->port_output && !wire->get_bool_attribute(ID::keep))
+			continue;
+		for (auto bit : sigmap(RTLIL::SigSpec(wire)))
+			if (bit.is_wire())
+				live.mark(bit.wire->driverCell_);
+	}
+
+	while (!live.worklist.empty()) {
+		RTLIL::Cell *cell = live.worklist.back();
+		live.worklist.pop_back();
+
+		for (auto &[port, sig] : cell->connections_) {
+			if (clean_ctx.ct_all.cell_known(cell->type_impl) &&
+					!clean_ctx.ct_all.cell_input(cell->type_impl, port))
+				continue;
+			for (auto bit : sig) {
+				if (!bit.is_wire())
+					continue;
+				live.mark(bit.wire->driverCell_);
+				if (!connect_cells.empty()) {
+					auto found = connect_cells.find(bit);
+					if (found != connect_cells.end())
+						for (RTLIL::Cell *connect : found->second)
+							live.mark(connect);
+				}
+			}
+		}
+
+		if (cell->type.in(TW($memrd), TW($memrd_v2))) {
+			std::string memid = cell->getParam(ID::MEMID).decode_string();
+			if (live_mems.insert(memid).second) {
+				auto found = mem_writers.find(memid);
+				if (found != mem_writers.end())
+					for (RTLIL::Cell *writer : found->second)
+						live.mark(writer);
+			}
+		}
+	}
+}
+
+bool sweep_cells(RTLIL::Module *module, const LiveSet &live, FfInitVals &ffinit,
+		CleanRunContext &clean_ctx)
+{
+	pool<RTLIL::Cell *> dead;
+	for (int i = 0; i < module->cells_size(); i++) {
+		RTLIL::Cell *cell = module->cell_at(i);
+		if (!live.cells.count(cell))
+			dead.insert(cell);
+	}
+	if (dead.empty())
+		return false;
+
+	dead.sort(RTLIL::sort_by_name<RTLIL::Cell>());
+	for (RTLIL::Cell *cell : dead) {
+		if (clean_ctx.flags.verbose)
+			log_debug("  removing unused `%s' cell `%s'.\n", cell->type, cell->name);
+		if (cell->is_builtin_ff())
+			ffinit.remove_init(cell->getPort(TW::Q));
+		module->remove(cell);
+		clean_ctx.stats.count_rm_cells++;
+	}
+	module->design->scratchpad_set_bool("opt.did_something", true);
+	return true;
+}
+
+void sweep_mems(RTLIL::Module *module, const pool<std::string> &live_mems, bool verbose)
+{
+	std::vector<TwineRef> dead;
+	for (auto &it : module->memories)
+		if (!live_mems.count(module->design->twines.str(it.first)))
+			dead.push_back(it.first);
+
+	for (TwineRef id : dead) {
+		if (verbose)
+			log_debug("  removing unused memory `%s'.\n", module->design->twines.str(id).c_str());
+		delete module->memories.at(id);
+		module->memories.erase(id);
+	}
+}
+
+pool<RTLIL::Wire *> referenced_wires(RTLIL::Module *module)
+{
+	pool<RTLIL::Wire *> referenced;
+	for (auto &[bit, portbits] : module->signorm_fanout())
+		if (bit.is_wire() && !portbits.empty())
+			referenced.insert(bit.wire);
+	for (int i = 0; i < module->wires_size(); i++) {
+		RTLIL::Wire *wire = module->wire_at(i);
+		if (wire->driverCell_ != nullptr)
+			referenced.insert(wire);
+	}
+	return referenced;
+}
+
+pool<RTLIL::SigBit> used_bits(RTLIL::Module *module, const SigMap &sigmap)
+{
+	pool<RTLIL::SigBit> used;
+	for (auto &[bit, portbits] : module->signorm_fanout())
+		if (!portbits.empty())
+			used.insert(bit);
+	for (int i = 0; i < module->wires_size(); i++) {
+		RTLIL::Wire *wire = module->wire_at(i);
+		if (wire->port_id > 0 && !wire->port_input)
+			for (auto bit : sigmap(RTLIL::SigSpec(wire)))
+				used.insert(bit);
+	}
+	return used;
+}
+
+void update_unused_bits(RTLIL::Module *module, const SigMap &sigmap)
+{
+	pool<RTLIL::SigBit> used = used_bits(module, sigmap);
+
+	for (int i = 0; i < module->wires_size(); i++) {
+		RTLIL::Wire *wire = module->wire_at(i);
+
+		std::string unused;
+		if (wire->port_id == 0)
+			for (int j = 0; j < GetSize(wire); j++) {
+				RTLIL::SigBit bit = sigmap(RTLIL::SigBit(wire, j));
+				if (!bit.is_wire() || used.count(bit))
+					continue;
+				if (!unused.empty())
+					unused += " ";
+				unused += stringf("%d", j);
+			}
+
+		if (unused.empty()) {
+			wire->attributes.erase(ID::unused_bits);
+		} else {
+			RTLIL::Const value(std::move(unused));
+			auto it = wire->attributes.find(ID::unused_bits);
+			if (it == wire->attributes.end() || it->second != value)
+				wire->attributes[ID::unused_bits] = std::move(value);
+		}
+	}
+}
+
+void normalize_inits(RTLIL::Module *module, const SigMap &sigmap)
+{
+	dict<RTLIL::SigBit, RTLIL::State> values;
+	pool<RTLIL::Wire *> representatives;
+
+	for (int i = 0; i < module->wires_size(); i++) {
+		RTLIL::Wire *wire = module->wire_at(i);
+		auto it = wire->attributes.find(ID::init);
+		if (it == wire->attributes.end())
+			continue;
+
+		RTLIL::Const val = it->second;
+		RTLIL::SigSpec sig = sigmap(RTLIL::SigSpec(wire));
+		for (int j = 0; j < GetSize(val) && j < GetSize(sig); j++)
+			if (val[j] != State::Sx && sig[j].is_wire()) {
+				values[sig[j]] = val[j];
+				representatives.insert(sig[j].wire);
+			}
+		wire->attributes.erase(it);
+	}
+
+	for (RTLIL::Wire *wire : representatives) {
+		bool found = false;
+		RTLIL::Const val(State::Sx, wire->width);
+		for (int j = 0; j < wire->width; j++) {
+			auto it = values.find(RTLIL::SigBit(wire, j));
+			if (it != values.end()) {
+				val.set(j, it->second);
+				found = true;
+			}
+		}
+		if (found)
+			wire->attributes[ID::init] = val;
+	}
+}
+
+bool wire_is_pinned(RTLIL::Wire *wire)
+{
+	if (wire->port_id != 0)
+		return true;
+	if (wire->get_bool_attribute(ID::keep))
+		return true;
+	auto init = wire->attributes.find(ID::init);
+	if (init != wire->attributes.end() && !init->second.is_fully_undef())
+		return true;
+	return false;
+}
+
+bool wire_is_live(RTLIL::Wire *wire, const pool<RTLIL::Wire *> &referenced)
+{
+	return wire_is_pinned(wire) || referenced.count(wire) != 0;
+}
+
+int sweep_wires(RTLIL::Module *module, CleanRunContext &clean_ctx)
+{
+	const SigMap *sigmap = module->signorm_sigmap();
+	log_assert(sigmap != nullptr);
+	pool<RTLIL::Wire *> referenced = referenced_wires(module);
+
+	pool<RTLIL::Wire *> dead;
+
+	for (int i = 0; i < module->wires_size(); i++) {
+		RTLIL::Wire *wire = module->wire_at(i);
+		if (wire_is_live(wire, referenced))
+			continue;
+
+		if (GetSize(wire) != 0 && !clean_ctx.flags.purge &&
+				check_public_name(wire->name.escaped())) {
+			bool aliases_live_net = false;
+			for (int j = 0; j < GetSize(wire); j++) {
+				RTLIL::SigBit bit(wire, j), rep = (*sigmap)(bit);
+				if (rep == bit)
+					continue;
+				if (!rep.is_wire() || wire_is_live(rep.wire, referenced)) {
+					aliases_live_net = true;
+					break;
+				}
+			}
+			if (aliases_live_net)
+				continue;
+		}
+
+		dead.insert(wire);
+	}
+
+	for (auto const &bit : sigmap->database) {
+		if (!bit.is_wire() || dead.count(bit.wire))
+			continue;
+		RTLIL::SigBit rep = (*sigmap)(bit);
+		if (rep.is_wire())
+			dead.erase(rep.wire);
+	}
+
+	if (dead.empty())
+		return 0;
+
+	int unreported = 0;
+	for (RTLIL::Wire *wire : dead) {
+		if (ys_debug() || (check_public_name(wire->name.escaped()) && clean_ctx.flags.verbose))
+			log_debug("  removing unused non-port wire %s.\n", wire->name);
+		else
+			unreported++;
+	}
+
+	module->signorm_compact(dead);
+	module->remove(dead);
+
+	clean_ctx.stats.count_rm_wires += GetSize(dead);
+	if (clean_ctx.flags.verbose && unreported)
+		log_debug("  removed %d unused temporary wires.\n", unreported);
+	return GetSize(dead);
+}
+
+PRIVATE_NAMESPACE_END
+
+YOSYS_NAMESPACE_BEGIN
+
+void rmunused_module_signorm(RTLIL::Module *module, ParallelDispatchThreadPool::Subpool &subpool,
+		CleanRunContext &clean_ctx)
+{
+	if (remove_buffer_cells(module, clean_ctx.flags.verbose))
+		module->design->scratchpad_set_bool("opt.did_something", true);
+
+	SigMap sigmap(module);
+	FfInitVals ffinit;
+	ffinit.set_parallel(&sigmap, subpool.thread_pool(), module);
+
+	LiveSet live;
+	pool<std::string> live_mems;
+	trace_live(module, live, live_mems, sigmap, clean_ctx);
+
+	sweep_cells(module, live, ffinit, clean_ctx);
+	sweep_mems(module, live_mems, clean_ctx.flags.verbose);
+
+	normalize_inits(module, sigmap);
+	sweep_wires(module, clean_ctx);
+
+	if (rmunused_module_init(module, subpool, clean_ctx.flags.verbose))
+		sweep_wires(module, clean_ctx);
+
+	SigMap swept(module);
+	update_unused_bits(module, swept);
+}
+
+YOSYS_NAMESPACE_END
diff --git a/passes/opt/opt_clean/wires.cc b/passes/opt/opt_clean/wires.cc
index 0ece62110..adeaa70bf 100644
--- a/passes/opt/opt_clean/wires.cc
+++ b/passes/opt/opt_clean/wires.cc
@@ -144,17 +144,6 @@ bool compare_signals(const RTLIL::SigBit &s1, const RTLIL::SigBit &s2, const Sha
 	return w2->name.lt_by_name(w1->name);
 }
 
-bool check_public_name(const std::string &id_str)
-{
-	if (!id_str.empty() && id_str[0] == '$')
-		return false;
-	if (id_str.rfind("\\_", 0) == 0 && (id_str.back() == '_' || id_str.find("_[") != std::string::npos))
-		return false;
-	if (id_str.find(".$") != std::string::npos)
-		return false;
-	return true;
-}
-
 void add_spec(ShardedSigPool::Builder &builder, const ThreadIndex &thread, const RTLIL::SigSpec &spec) {
 	for (SigBit bit : spec)
 		if (bit.wire != nullptr)
@@ -533,6 +522,17 @@ PRIVATE_NAMESPACE_END
 
 YOSYS_NAMESPACE_BEGIN
 
+bool check_public_name(const std::string &id_str)
+{
+	if (!id_str.empty() && id_str[0] == '$')
+		return false;
+	if (id_str.rfind("\\_", 0) == 0 && (id_str.back() == '_' || id_str.find("_[") != std::string::npos))
+		return false;
+	if (id_str.find(".$") != std::string::npos)
+		return false;
+	return true;
+}
+
 bool rmunused_module_signals(RTLIL::Module *module, ParallelDispatchThreadPool::Subpool &subpool, CleanRunContext &clean_ctx)
 {
 	// Passing actx to function == function does parallel work
diff --git a/passes/opt/opt_dff.cc b/passes/opt/opt_dff.cc
index 9485fe733..e08e2fe70 100644
--- a/passes/opt/opt_dff.cc
+++ b/passes/opt/opt_dff.cc
@@ -1454,7 +1454,6 @@ struct OptDffPass : public Pass {
 			break;
 		}
 		extra_args(args, argidx, design);
-		// TODO extra wires signorm adds breaks muxtree traversal or requires sigmapping
 		design->sigNormalize(false);
 
 		// The SAT engine reasons in 2-valued logic (a constant x is treated as