Merge pull request #2105 from whitequark/split-flatten-off-techmap

Split `flatten` from `techmap` and simplify it

5 files changed, 541 insertions, 325 deletions

diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index 397edc4e7..109113370 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -1885,6 +1885,18 @@ RTLIL::Cell *RTLIL::Module::addCell(RTLIL::IdString name, const RTLIL::Cell *oth
 	return cell;
 }
 
+RTLIL::Memory *RTLIL::Module::addMemory(RTLIL::IdString name, const RTLIL::Memory *other)
+{
+	RTLIL::Memory *mem = new RTLIL::Memory;
+	mem->name = name;
+	mem->width = other->width;
+	mem->start_offset = other->start_offset;
+	mem->size = other->size;
+	mem->attributes = other->attributes;
+	memories[mem->name] = mem;
+	return mem;
+}
+
 #define DEF_METHOD(_func, _y_size, _type) \
 	RTLIL::Cell* RTLIL::Module::add ## _func(RTLIL::IdString name, const RTLIL::SigSpec &sig_a, const RTLIL::SigSpec &sig_y, bool is_signed, const std::string &src) { \
 		RTLIL::Cell *cell = addCell(name, _type);           \
diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index 51e573e76..86b4e25b6 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -1170,6 +1170,8 @@ public:
 	RTLIL::Cell *addCell(RTLIL::IdString name, RTLIL::IdString type);
 	RTLIL::Cell *addCell(RTLIL::IdString name, const RTLIL::Cell *other);
 
+	RTLIL::Memory *addMemory(RTLIL::IdString name, const RTLIL::Memory *other);
+
 	// The add* methods create a cell and return the created cell. All signals must exist in advance.
 
 	RTLIL::Cell* addNot (RTLIL::IdString name, const RTLIL::SigSpec &sig_a, const RTLIL::SigSpec &sig_y, bool is_signed = false, const std::string &src = "");
diff --git a/passes/techmap/Makefile.inc b/passes/techmap/Makefile.inc
index 873286608..a54b4913d 100644
--- a/passes/techmap/Makefile.inc
+++ b/passes/techmap/Makefile.inc
@@ -1,4 +1,5 @@
 
+OBJS += passes/techmap/flatten.o
 OBJS += passes/techmap/techmap.o
 OBJS += passes/techmap/simplemap.o
 OBJS += passes/techmap/dfflibmap.o
diff --git a/passes/techmap/flatten.cc b/passes/techmap/flatten.cc
new file mode 100644
index 000000000..027bb137d
--- /dev/null
+++ b/passes/techmap/flatten.cc
@@ -0,0 +1,357 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#include "kernel/yosys.h"
+#include "kernel/utils.h"
+#include "kernel/sigtools.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+USING_YOSYS_NAMESPACE
+PRIVATE_NAMESPACE_BEGIN
+
+void apply_prefix(IdString prefix, IdString &id)
+{
+	if (id[0] == '\\')
+		id = stringf("%s.%s", prefix.c_str(), id.c_str()+1);
+	else
+		id = stringf("$flatten%s.%s", prefix.c_str(), id.c_str());
+}
+
+void apply_prefix(IdString prefix, RTLIL::SigSpec &sig, RTLIL::Module *module)
+{
+	vector<SigChunk> chunks = sig;
+	for (auto &chunk : chunks)
+		if (chunk.wire != nullptr) {
+			IdString wire_name = chunk.wire->name;
+			apply_prefix(prefix, wire_name);
+			log_assert(module->wire(wire_name) != nullptr);
+			chunk.wire = module->wire(wire_name);
+		}
+	sig = chunks;
+}
+
+struct FlattenWorker
+{
+	bool ignore_wb = false;
+
+	void flatten_cell(RTLIL::Design *design, RTLIL::Module *module, RTLIL::Cell *cell, RTLIL::Module *tpl, std::vector<RTLIL::Cell*> &new_cells)
+	{
+		if (tpl->processes.size() != 0) {
+			log("Flattening yielded processes:");
+			for (auto &it : tpl->processes)
+				log(" %s",log_id(it.first));
+			log("\n");
+			log_error("Flattening yielded processes -> this is not supported.\n");
+		}
+
+		pool<string> extra_src_attrs = cell->get_strpool_attribute(ID::src);
+
+		dict<IdString, IdString> memory_renames;
+
+		for (auto &it : tpl->memories) {
+			IdString m_name = it.first;
+			apply_prefix(cell->name, m_name);
+			RTLIL::Memory *m = module->addMemory(m_name, it.second);
+			if (m->attributes.count(ID::src))
+				m->add_strpool_attribute(ID::src, extra_src_attrs);
+			memory_renames[it.first] = m->name;
+			design->select(module, m);
+		}
+
+		dict<IdString, IdString> positional_ports;
+		dict<Wire*, IdString> temp_renamed_wires;
+
+		for (auto tpl_w : tpl->wires())
+		{
+			if (tpl_w->port_id > 0)
+			{
+				IdString posportname = stringf("$%d", tpl_w->port_id);
+				positional_ports.emplace(posportname, tpl_w->name);
+			}
+			IdString w_name = tpl_w->name;
+			apply_prefix(cell->name, w_name);
+			RTLIL::Wire *w = module->wire(w_name);
+			if (w != nullptr) {
+				if (!w->get_bool_attribute(ID::hierconn)) {
+					temp_renamed_wires[w] = w->name;
+					module->rename(w, NEW_ID);
+					w = nullptr;
+				} else {
+					w->attributes.erase(ID::hierconn);
+					if (GetSize(w) < GetSize(tpl_w)) {
+						log_warning("Widening signal %s.%s to match size of %s.%s (via %s.%s).\n", log_id(module), log_id(w),
+								log_id(tpl), log_id(tpl_w), log_id(module), log_id(cell));
+						w->width = GetSize(tpl_w);
+					}
+				}
+			}
+			if (w == nullptr) {
+				w = module->addWire(w_name, tpl_w);
+				w->port_input = false;
+				w->port_output = false;
+				w->port_id = 0;
+				if (w->attributes.count(ID::src))
+					w->add_strpool_attribute(ID::src, extra_src_attrs);
+			}
+			design->select(module, w);
+		}
+
+		SigMap sigmap(module);
+
+		SigMap tpl_sigmap(tpl);
+		pool<SigBit> tpl_written_bits;
+
+		for (auto tpl_cell : tpl->cells())
+		for (auto &conn : tpl_cell->connections())
+			if (tpl_cell->output(conn.first))
+				for (auto bit : tpl_sigmap(conn.second))
+					tpl_written_bits.insert(bit);
+		for (auto &conn : tpl->connections())
+			for (auto bit : tpl_sigmap(conn.first))
+				tpl_written_bits.insert(bit);
+
+		SigMap port_signal_map;
+
+		for (auto &it : cell->connections())
+		{
+			IdString portname = it.first;
+			if (positional_ports.count(portname) > 0)
+				portname = positional_ports.at(portname);
+			if (tpl->wire(portname) == nullptr || tpl->wire(portname)->port_id == 0) {
+				if (portname.begins_with("$"))
+					log_error("Can't map port `%s' of cell `%s' to template `%s'!\n", portname.c_str(), cell->name.c_str(), tpl->name.c_str());
+				continue;
+			}
+
+			if (GetSize(it.second) == 0)
+				continue;
+
+			RTLIL::Wire *w = tpl->wire(portname);
+			RTLIL::SigSig c;
+
+			if (w->port_output && !w->port_input) {
+				c.first = it.second;
+				c.second = RTLIL::SigSpec(w);
+				apply_prefix(cell->name, c.second, module);
+			} else if (!w->port_output && w->port_input) {
+				c.first = RTLIL::SigSpec(w);
+				c.second = it.second;
+				apply_prefix(cell->name, c.first, module);
+			} else {
+				SigSpec sig_tpl = w, sig_tpl_pf = w, sig_mod = it.second;
+				apply_prefix(cell->name, sig_tpl_pf, module);
+				for (int i = 0; i < GetSize(sig_tpl) && i < GetSize(sig_mod); i++) {
+					if (tpl_written_bits.count(tpl_sigmap(sig_tpl[i]))) {
+						c.first.append(sig_mod[i]);
+						c.second.append(sig_tpl_pf[i]);
+					} else {
+						c.first.append(sig_tpl_pf[i]);
+						c.second.append(sig_mod[i]);
+					}
+				}
+			}
+
+			if (c.second.size() > c.first.size())
+				c.second.remove(c.first.size(), c.second.size() - c.first.size());
+
+			if (c.second.size() < c.first.size())
+				c.second.append(RTLIL::SigSpec(RTLIL::State::S0, c.first.size() - c.second.size()));
+
+			log_assert(c.first.size() == c.second.size());
+
+			// connect internal and external wires
+
+			if (sigmap(c.first).has_const())
+				log_error("Mismatch in directionality for cell port %s.%s.%s: %s <= %s\n",
+					log_id(module), log_id(cell), log_id(it.first), log_signal(c.first), log_signal(c.second));
+
+			module->connect(c);
+		}
+
+		for (auto tpl_cell : tpl->cells())
+		{
+			IdString c_name = tpl_cell->name;
+			apply_prefix(cell->name, c_name);
+
+			RTLIL::Cell *c = module->addCell(c_name, tpl_cell);
+			new_cells.push_back(c);
+			design->select(module, c);
+
+			for (auto &conn : c->connections())
+			{
+				RTLIL::SigSpec new_conn = conn.second;
+				apply_prefix(cell->name, new_conn, module);
+				port_signal_map.apply(new_conn);
+				c->setPort(conn.first, std::move(new_conn));
+			}
+
+			if (c->type.in(ID($memrd), ID($memwr), ID($meminit))) {
+				IdString memid = c->getParam(ID::MEMID).decode_string();
+				log_assert(memory_renames.count(memid) != 0);
+				c->setParam(ID::MEMID, Const(memory_renames[memid].str()));
+			}
+
+			if (c->type == ID($mem)) {
+				IdString memid = c->getParam(ID::MEMID).decode_string();
+				apply_prefix(cell->name, memid);
+				c->setParam(ID::MEMID, Const(memid.c_str()));
+			}
+
+			if (c->attributes.count(ID::src))
+				c->add_strpool_attribute(ID::src, extra_src_attrs);
+		}
+
+		for (auto &it : tpl->connections()) {
+			RTLIL::SigSig c = it;
+			apply_prefix(cell->name.str(), c.first, module);
+			apply_prefix(cell->name.str(), c.second, module);
+			port_signal_map.apply(c.first);
+			port_signal_map.apply(c.second);
+			module->connect(c);
+		}
+
+		module->remove(cell);
+
+		for (auto &it : temp_renamed_wires)
+		{
+			Wire *w = it.first;
+			IdString name = it.second;
+			IdString altname = module->uniquify(name);
+			Wire *other_w = module->wire(name);
+			module->rename(other_w, altname);
+			module->rename(w, name);
+		}
+	}
+
+	void flatten_module(RTLIL::Design *design, RTLIL::Module *module, pool<RTLIL::Module*> &used_modules)
+	{
+		if (!design->selected(module) || module->get_blackbox_attribute(ignore_wb))
+			return;
+
+		std::vector<RTLIL::Cell*> worklist = module->selected_cells();
+		while (!worklist.empty())
+		{
+			RTLIL::Cell *cell = worklist.back();
+			worklist.pop_back();
+
+			if (!design->has(cell->type))
+				continue;
+
+			RTLIL::Module *tpl = design->module(cell->type);
+			if (tpl->get_blackbox_attribute(ignore_wb))
+				continue;
+
+			if (cell->get_bool_attribute(ID::keep_hierarchy) || tpl->get_bool_attribute(ID::keep_hierarchy)) {
+				log("Keeping %s.%s (found keep_hierarchy attribute).\n", log_id(module), log_id(cell));
+				used_modules.insert(tpl);
+				continue;
+			}
+
+			log_debug("Flattening %s.%s (%s).\n", log_id(module), log_id(cell), log_id(cell->type));
+			// If a design is fully selected and has a top module defined, topological sorting ensures that all cells
+			// added during flattening are black boxes, and flattening is finished in one pass. However, when flattening
+			// individual modules, this isn't the case, and the newly added cells might have to be flattened further.
+			flatten_cell(design, module, cell, tpl, worklist);
+		}
+	}
+};
+
+struct FlattenPass : public Pass {
+	FlattenPass() : Pass("flatten", "flatten design") { }
+	void help() YS_OVERRIDE
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    flatten [options] [selection]\n");
+		log("\n");
+		log("This pass flattens the design by replacing cells by their implementation. This\n");
+		log("pass is very similar to the 'techmap' pass. The only difference is that this\n");
+		log("pass is using the current design as mapping library.\n");
+		log("\n");
+		log("Cells and/or modules with the 'keep_hierarchy' attribute set will not be\n");
+		log("flattened by this command.\n");
+		log("\n");
+		log("    -wb\n");
+		log("        Ignore the 'whitebox' attribute on cell implementations.\n");
+		log("\n");
+	}
+	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
+	{
+		log_header(design, "Executing FLATTEN pass (flatten design).\n");
+		log_push();
+
+		FlattenWorker worker;
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++) {
+			if (args[argidx] == "-wb") {
+				worker.ignore_wb = true;
+				continue;
+			}
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		RTLIL::Module *top = nullptr;
+		if (design->full_selection())
+			for (auto module : design->modules())
+				if (module->get_bool_attribute(ID::top))
+					top = module;
+
+		pool<RTLIL::Module*> used_modules;
+		if (top == nullptr)
+			used_modules = design->modules();
+		else
+			used_modules.insert(top);
+
+		TopoSort<RTLIL::Module*, IdString::compare_ptr_by_name<RTLIL::Module>> topo_modules;
+		pool<RTLIL::Module*> worklist = used_modules;
+		while (!worklist.empty()) {
+			RTLIL::Module *module = worklist.pop();
+			for (auto cell : module->selected_cells()) {
+				RTLIL::Module *tpl = design->module(cell->type);
+				if (tpl != nullptr) {
+					if (topo_modules.database.count(tpl) == 0)
+						worklist.insert(tpl);
+					topo_modules.edge(tpl, module);
+				}
+			}
+		}
+
+		if (!topo_modules.sort())
+			log_error("Cannot flatten a design containing recursive instantiations.\n");
+
+		for (auto module : topo_modules.sorted)
+			worker.flatten_module(design, module, used_modules);
+
+		if (top != nullptr)
+			for (auto module : design->modules().to_vector())
+				if (!used_modules[module] && !module->get_blackbox_attribute(worker.ignore_wb)) {
+					log("Deleting now unused module %s.\n", log_id(module));
+					design->remove(module);
+				}
+
+		log_pop();
+	}
+} FlattenPass;
+
+PRIVATE_NAMESPACE_END
diff --git a/passes/techmap/techmap.cc b/passes/techmap/techmap.cc
index c88f7bd0a..535db9465 100644
--- a/passes/techmap/techmap.cc
+++ b/passes/techmap/techmap.cc
@@ -67,10 +67,6 @@ struct TechmapWorker
 	pool<RTLIL::Module*> module_queue;
 	dict<Module*, SigMap> sigmaps;
 
-	pool<IdString> flatten_do_list;
-	pool<IdString> flatten_done_list;
-	pool<Cell*> flatten_keep_list;
-
 	pool<string> log_msg_cache;
 
 	struct TechmapWireData {
@@ -82,7 +78,6 @@ struct TechmapWorker
 
 	bool extern_mode = false;
 	bool assert_mode = false;
-	bool flatten_mode = false;
 	bool recursive_mode = false;
 	bool autoproc_mode = false;
 	bool ignore_wb = false;
@@ -168,28 +163,20 @@ struct TechmapWorker
 		pool<string> extra_src_attrs = cell->get_strpool_attribute(ID::src);
 
 		orig_cell_name = cell->name.str();
-		if (!flatten_mode) {
-			for (auto tpl_cell : tpl->cells())
-				if (tpl_cell->name == ID::_TECHMAP_REPLACE_) {
-					module->rename(cell, stringf("$techmap%d", autoidx++) + cell->name.str());
-					break;
-				}
-		}
+		for (auto tpl_cell : tpl->cells())
+			if (tpl_cell->name == ID::_TECHMAP_REPLACE_) {
+				module->rename(cell, stringf("$techmap%d", autoidx++) + cell->name.str());
+				break;
+			}
 
 		dict<IdString, IdString> memory_renames;
 
 		for (auto &it : tpl->memories) {
 			IdString m_name = it.first;
 			apply_prefix(cell->name, m_name);
-			RTLIL::Memory *m = new RTLIL::Memory;
-			m->name = m_name;
-			m->width = it.second->width;
-			m->start_offset = it.second->start_offset;
-			m->size = it.second->size;
-			m->attributes = it.second->attributes;
+			RTLIL::Memory *m = module->addMemory(m_name, it.second);
 			if (m->attributes.count(ID::src))
 				m->add_strpool_attribute(ID::src, extra_src_attrs);
-			module->memories[m->name] = m;
 			memory_renames[it.first] = m->name;
 			design->select(module, m);
 		}
@@ -205,7 +192,7 @@ struct TechmapWorker
 				IdString posportname = stringf("$%d", tpl_w->port_id);
 				positional_ports.emplace(posportname, tpl_w->name);
 
-				if (!flatten_mode && tpl_w->get_bool_attribute(ID::techmap_autopurge) &&
+				if (tpl_w->get_bool_attribute(ID::techmap_autopurge) &&
 						(!cell->hasPort(tpl_w->name) || !GetSize(cell->getPort(tpl_w->name))) &&
 						(!cell->hasPort(posportname) || !GetSize(cell->getPort(posportname))))
 				{
@@ -221,26 +208,16 @@ struct TechmapWorker
 			apply_prefix(cell->name, w_name);
 			RTLIL::Wire *w = module->wire(w_name);
 			if (w != nullptr) {
-				if (!flatten_mode || !w->get_bool_attribute(ID::hierconn)) {
-					temp_renamed_wires[w] = w->name;
-					module->rename(w, NEW_ID);
-					w = nullptr;
-				} else {
-					w->attributes.erase(ID::hierconn);
-					if (GetSize(w) < GetSize(tpl_w)) {
-						log_warning("Widening signal %s.%s to match size of %s.%s (via %s.%s).\n", log_id(module), log_id(w),
-								log_id(tpl), log_id(tpl_w), log_id(module), log_id(cell));
-						w->width = GetSize(tpl_w);
-					}
-				}
+				temp_renamed_wires[w] = w->name;
+				module->rename(w, NEW_ID);
+				w = nullptr;
 			}
 			if (w == nullptr) {
 				w = module->addWire(w_name, tpl_w);
 				w->port_input = false;
 				w->port_output = false;
 				w->port_id = 0;
-				if (!flatten_mode)
-					w->attributes.erase(ID::techmap_autopurge);
+				w->attributes.erase(ID::techmap_autopurge);
 				if (tpl_w->get_bool_attribute(ID::_techmap_special_))
 					w->attributes.clear();
 				if (w->attributes.count(ID::src))
@@ -322,56 +299,37 @@ struct TechmapWorker
 
 			log_assert(c.first.size() == c.second.size());
 
-			if (flatten_mode)
-			{
-				// more conservative approach:
-				// connect internal and external wires
-
-				if (sigmaps.count(module) == 0)
-					sigmaps[module].set(module);
-
-				if (sigmaps.at(module)(c.first).has_const())
-					log_error("Mismatch in directionality for cell port %s.%s.%s: %s <= %s\n",
-						log_id(module), log_id(cell), log_id(it.first), log_signal(c.first), log_signal(c.second));
+			// replace internal wires that are connected to external wires
 
+			if (w->port_output && !w->port_input) {
+				port_signal_map.add(c.second, c.first);
+			} else
+			if (!w->port_output && w->port_input) {
+				port_signal_map.add(c.first, c.second);
+			} else {
 				module->connect(c);
+				extra_connect = SigSig();
 			}
-			else
-			{
-				// approach that yields nicer outputs:
-				// replace internal wires that are connected to external wires
-
-				if (w->port_output && !w->port_input) {
-					port_signal_map.add(c.second, c.first);
-				} else
-				if (!w->port_output && w->port_input) {
-					port_signal_map.add(c.first, c.second);
-				} else {
-					module->connect(c);
-					extra_connect = SigSig();
-				}
 
-				for (auto &attr : w->attributes) {
-					if (attr.first == ID::src)
-						continue;
-					auto lhs = GetSize(extra_connect.first);
-					auto rhs = GetSize(extra_connect.second);
-					if (lhs > rhs)
-						extra_connect.first.remove(rhs, lhs-rhs);
-					else if (rhs > lhs)
-						extra_connect.second.remove(lhs, rhs-lhs);
-					module->connect(extra_connect);
-					break;
-				}
+			for (auto &attr : w->attributes) {
+				if (attr.first == ID::src)
+					continue;
+				auto lhs = GetSize(extra_connect.first);
+				auto rhs = GetSize(extra_connect.second);
+				if (lhs > rhs)
+					extra_connect.first.remove(rhs, lhs-rhs);
+				else if (rhs > lhs)
+					extra_connect.second.remove(lhs, rhs-lhs);
+				module->connect(extra_connect);
+				break;
 			}
 		}
 
 		for (auto tpl_cell : tpl->cells())
 		{
 			IdString c_name = tpl_cell->name;
-			bool techmap_replace_cell = (!flatten_mode) && (c_name == ID::_TECHMAP_REPLACE_);
 
-			if (techmap_replace_cell)
+			if (c_name == ID::_TECHMAP_REPLACE_)
 				c_name = orig_cell_name;
 			else if (tpl_cell->name.begins_with("\\_TECHMAP_REPLACE_."))
 				c_name = stringf("%s%s", orig_cell_name.c_str(), c_name.c_str() + strlen("\\_TECHMAP_REPLACE_"));
@@ -381,7 +339,7 @@ struct TechmapWorker
 			RTLIL::Cell *c = module->addCell(c_name, tpl_cell);
 			design->select(module, c);
 
-			if (!flatten_mode && c->type.begins_with("\\$"))
+			if (c->type.begins_with("\\$"))
 				c->type = c->type.substr(1);
 
 			vector<IdString> autopurge_ports;
@@ -426,7 +384,7 @@ struct TechmapWorker
 			if (c->attributes.count(ID::src))
 				c->add_strpool_attribute(ID::src, extra_src_attrs);
 
-			if (techmap_replace_cell)
+			if (c_name == ID::_TECHMAP_REPLACE_)
 				for (auto attr : cell->attributes)
 					if (!c->attributes.count(attr.first))
 						c->attributes[attr.first] = attr.second;
@@ -499,22 +457,6 @@ struct TechmapWorker
 				continue;
 			}
 
-			if (flatten_mode) {
-				bool keepit = cell->get_bool_attribute(ID::keep_hierarchy);
-				for (auto &tpl_name : celltypeMap.at(cell_type))
-					if (map->module(tpl_name)->get_bool_attribute(ID::keep_hierarchy))
-						keepit = true;
-				if (keepit) {
-					if (!flatten_keep_list[cell]) {
-						log("Keeping %s.%s (found keep_hierarchy property).\n", log_id(module), log_id(cell));
-						flatten_keep_list.insert(cell);
-					}
-					if (!flatten_done_list[cell->type])
-						flatten_do_list.insert(cell->type);
-					continue;
-				}
-			}
-
 			for (auto &conn : cell->connections())
 			{
 				RTLIL::SigSpec sig = sigmap(conn.second);
@@ -564,172 +506,171 @@ struct TechmapWorker
 				if (tpl->get_blackbox_attribute(ignore_wb))
 					continue;
 
-				if (!flatten_mode)
-				{
-					std::string extmapper_name;
-
-					if (tpl->get_bool_attribute(ID::techmap_simplemap))
-						extmapper_name = "simplemap";
+				std::string extmapper_name;
 
-					if (tpl->get_bool_attribute(ID::techmap_maccmap))
-						extmapper_name = "maccmap";
+				if (tpl->get_bool_attribute(ID::techmap_simplemap))
+					extmapper_name = "simplemap";
 
-					if (tpl->attributes.count(ID::techmap_wrap))
-						extmapper_name = "wrap";
+				if (tpl->get_bool_attribute(ID::techmap_maccmap))
+					extmapper_name = "maccmap";
 
-					if (!extmapper_name.empty())
-					{
-						cell->type = cell_type;
+				if (tpl->attributes.count(ID::techmap_wrap))
+					extmapper_name = "wrap";
 
-						if ((extern_mode && !in_recursion) || extmapper_name == "wrap")
-						{
-							std::string m_name = stringf("$extern:%s:%s", extmapper_name.c_str(), log_id(cell->type));
-
-							for (auto &c : cell->parameters)
-								m_name += stringf(":%s=%s", log_id(c.first), log_signal(c.second));
-
-							if (extmapper_name == "wrap")
-								m_name += ":" + sha1(tpl->attributes.at(ID::techmap_wrap).decode_string());
-
-							RTLIL::Design *extmapper_design = extern_mode && !in_recursion ? design : tpl->design;
-							RTLIL::Module *extmapper_module = extmapper_design->module(m_name);
+				if (!extmapper_name.empty())
+				{
+					cell->type = cell_type;
 
-							if (extmapper_module == nullptr)
-							{
-								extmapper_module = extmapper_design->addModule(m_name);
-								RTLIL::Cell *extmapper_cell = extmapper_module->addCell(cell->type, cell);
-
-								extmapper_cell->set_src_attribute(cell->get_src_attribute());
-
-								int port_counter = 1;
-								for (auto &c : extmapper_cell->connections_) {
-									RTLIL::Wire *w = extmapper_module->addWire(c.first, GetSize(c.second));
-									if (w->name.in(ID::Y, ID::Q))
-										w->port_output = true;
-									else
-										w->port_input = true;
-									w->port_id = port_counter++;
-									c.second = w;
-								}
+					if ((extern_mode && !in_recursion) || extmapper_name == "wrap")
+					{
+						std::string m_name = stringf("$extern:%s:%s", extmapper_name.c_str(), log_id(cell->type));
 
-								extmapper_module->fixup_ports();
-								extmapper_module->check();
+						for (auto &c : cell->parameters)
+							m_name += stringf(":%s=%s", log_id(c.first), log_signal(c.second));
 
-								if (extmapper_name == "simplemap") {
-									log("Creating %s with simplemap.\n", log_id(extmapper_module));
-									if (simplemap_mappers.count(extmapper_cell->type) == 0)
-										log_error("No simplemap mapper for cell type %s found!\n", log_id(extmapper_cell->type));
-									simplemap_mappers.at(extmapper_cell->type)(extmapper_module, extmapper_cell);
-									extmapper_module->remove(extmapper_cell);
-								}
+						if (extmapper_name == "wrap")
+							m_name += ":" + sha1(tpl->attributes.at(ID::techmap_wrap).decode_string());
 
-								if (extmapper_name == "maccmap") {
-									log("Creating %s with maccmap.\n", log_id(extmapper_module));
-									if (extmapper_cell->type != ID($macc))
-										log_error("The maccmap mapper can only map $macc (not %s) cells!\n", log_id(extmapper_cell->type));
-									maccmap(extmapper_module, extmapper_cell);
-									extmapper_module->remove(extmapper_cell);
-								}
+						RTLIL::Design *extmapper_design = extern_mode && !in_recursion ? design : tpl->design;
+						RTLIL::Module *extmapper_module = extmapper_design->module(m_name);
 
-								if (extmapper_name == "wrap") {
-									std::string cmd_string = tpl->attributes.at(ID::techmap_wrap).decode_string();
-									log("Running \"%s\" on wrapper %s.\n", cmd_string.c_str(), log_id(extmapper_module));
-									mkdebug.on();
-									Pass::call_on_module(extmapper_design, extmapper_module, cmd_string);
-									log_continue = true;
-								}
+						if (extmapper_module == nullptr)
+						{
+							extmapper_module = extmapper_design->addModule(m_name);
+							RTLIL::Cell *extmapper_cell = extmapper_module->addCell(cell->type, cell);
+
+							extmapper_cell->set_src_attribute(cell->get_src_attribute());
+
+							int port_counter = 1;
+							for (auto &c : extmapper_cell->connections_) {
+								RTLIL::Wire *w = extmapper_module->addWire(c.first, GetSize(c.second));
+								if (w->name.in(ID::Y, ID::Q))
+									w->port_output = true;
+								else
+									w->port_input = true;
+								w->port_id = port_counter++;
+								c.second = w;
 							}
 
-							cell->type = extmapper_module->name;
-							cell->parameters.clear();
+							extmapper_module->fixup_ports();
+							extmapper_module->check();
 
-							if (!extern_mode || in_recursion) {
-								tpl = extmapper_module;
-								goto use_wrapper_tpl;
+							if (extmapper_name == "simplemap") {
+								log("Creating %s with simplemap.\n", log_id(extmapper_module));
+								if (simplemap_mappers.count(extmapper_cell->type) == 0)
+									log_error("No simplemap mapper for cell type %s found!\n", log_id(extmapper_cell->type));
+								simplemap_mappers.at(extmapper_cell->type)(extmapper_module, extmapper_cell);
+								extmapper_module->remove(extmapper_cell);
 							}
 
-							auto msg = stringf("Using extmapper %s for cells of type %s.", log_id(extmapper_module), log_id(cell->type));
-							if (!log_msg_cache.count(msg)) {
-								log_msg_cache.insert(msg);
-								log("%s\n", msg.c_str());
-							}
-							log_debug("%s %s.%s (%s) to %s.\n", mapmsg_prefix.c_str(), log_id(module), log_id(cell), log_id(cell->type), log_id(extmapper_module));
-						}
-						else
-						{
-							auto msg = stringf("Using extmapper %s for cells of type %s.", extmapper_name.c_str(), log_id(cell->type));
-							if (!log_msg_cache.count(msg)) {
-								log_msg_cache.insert(msg);
-								log("%s\n", msg.c_str());
+							if (extmapper_name == "maccmap") {
+								log("Creating %s with maccmap.\n", log_id(extmapper_module));
+								if (extmapper_cell->type != ID($macc))
+									log_error("The maccmap mapper can only map $macc (not %s) cells!\n", log_id(extmapper_cell->type));
+								maccmap(extmapper_module, extmapper_cell);
+								extmapper_module->remove(extmapper_cell);
 							}
-							log_debug("%s %s.%s (%s) with %s.\n", mapmsg_prefix.c_str(), log_id(module), log_id(cell), log_id(cell->type), extmapper_name.c_str());
 
-							if (extmapper_name == "simplemap") {
-								if (simplemap_mappers.count(cell->type) == 0)
-									log_error("No simplemap mapper for cell type %s found!\n", log_id(cell->type));
-								simplemap_mappers.at(cell->type)(module, cell);
+							if (extmapper_name == "wrap") {
+								std::string cmd_string = tpl->attributes.at(ID::techmap_wrap).decode_string();
+								log("Running \"%s\" on wrapper %s.\n", cmd_string.c_str(), log_id(extmapper_module));
+								mkdebug.on();
+								Pass::call_on_module(extmapper_design, extmapper_module, cmd_string);
+								log_continue = true;
 							}
+						}
 
-							if (extmapper_name == "maccmap") {
-								if (cell->type != ID($macc))
-									log_error("The maccmap mapper can only map $macc (not %s) cells!\n", log_id(cell->type));
-								maccmap(module, cell);
-							}
+						cell->type = extmapper_module->name;
+						cell->parameters.clear();
 
-							module->remove(cell);
-							cell = nullptr;
+						if (!extern_mode || in_recursion) {
+							tpl = extmapper_module;
+							goto use_wrapper_tpl;
 						}
 
-						did_something = true;
-						mapped_cell = true;
-						break;
+						auto msg = stringf("Using extmapper %s for cells of type %s.", log_id(extmapper_module), log_id(cell->type));
+						if (!log_msg_cache.count(msg)) {
+							log_msg_cache.insert(msg);
+							log("%s\n", msg.c_str());
+						}
+						log_debug("%s %s.%s (%s) to %s.\n", mapmsg_prefix.c_str(), log_id(module), log_id(cell), log_id(cell->type), log_id(extmapper_module));
 					}
+					else
+					{
+						auto msg = stringf("Using extmapper %s for cells of type %s.", extmapper_name.c_str(), log_id(cell->type));
+						if (!log_msg_cache.count(msg)) {
+							log_msg_cache.insert(msg);
+							log("%s\n", msg.c_str());
+						}
+						log_debug("%s %s.%s (%s) with %s.\n", mapmsg_prefix.c_str(), log_id(module), log_id(cell), log_id(cell->type), extmapper_name.c_str());
 
-					for (auto &conn : cell->connections()) {
-						if (conn.first.begins_with("$"))
-							continue;
-						if (tpl->wire(conn.first) != nullptr && tpl->wire(conn.first)->port_id > 0)
-							continue;
-						if (!conn.second.is_fully_const() || parameters.count(conn.first) > 0 || tpl->avail_parameters.count(conn.first) == 0)
-							goto next_tpl;
-						parameters[conn.first] = conn.second.as_const();
+						if (extmapper_name == "simplemap") {
+							if (simplemap_mappers.count(cell->type) == 0)
+								log_error("No simplemap mapper for cell type %s found!\n", log_id(cell->type));
+							simplemap_mappers.at(cell->type)(module, cell);
+						}
+
+						if (extmapper_name == "maccmap") {
+							if (cell->type != ID($macc))
+								log_error("The maccmap mapper can only map $macc (not %s) cells!\n", log_id(cell->type));
+							maccmap(module, cell);
+						}
+
+						module->remove(cell);
+						cell = nullptr;
 					}
 
-					if (0) {
-			next_tpl:
+					did_something = true;
+					mapped_cell = true;
+					break;
+				}
+
+				for (auto &conn : cell->connections()) {
+					if (conn.first.begins_with("$"))
 						continue;
-					}
+					if (tpl->wire(conn.first) != nullptr && tpl->wire(conn.first)->port_id > 0)
+						continue;
+					if (!conn.second.is_fully_const() || parameters.count(conn.first) > 0 || tpl->avail_parameters.count(conn.first) == 0)
+						goto next_tpl;
+					parameters[conn.first] = conn.second.as_const();
+				}
 
-					if (tpl->avail_parameters.count(ID::_TECHMAP_CELLTYPE_) != 0)
-						parameters.emplace(ID::_TECHMAP_CELLTYPE_, RTLIL::unescape_id(cell->type));
+				if (0) {
+		next_tpl:
+					continue;
+				}
 
-					for (auto &conn : cell->connections()) {
-						if (tpl->avail_parameters.count(stringf("\\_TECHMAP_CONSTMSK_%s_", log_id(conn.first))) != 0) {
-							std::vector<RTLIL::SigBit> v = sigmap(conn.second).to_sigbit_vector();
-							for (auto &bit : v)
-								bit = RTLIL::SigBit(bit.wire == nullptr ? RTLIL::State::S1 : RTLIL::State::S0);
-							parameters.emplace(stringf("\\_TECHMAP_CONSTMSK_%s_", log_id(conn.first)), RTLIL::SigSpec(v).as_const());
-						}
-						if (tpl->avail_parameters.count(stringf("\\_TECHMAP_CONSTVAL_%s_", log_id(conn.first))) != 0) {
-							std::vector<RTLIL::SigBit> v = sigmap(conn.second).to_sigbit_vector();
-							for (auto &bit : v)
-								if (bit.wire != nullptr)
-									bit = RTLIL::SigBit(RTLIL::State::Sx);
-							parameters.emplace(stringf("\\_TECHMAP_CONSTVAL_%s_", log_id(conn.first)), RTLIL::SigSpec(v).as_const());
-						}
-						if (tpl->avail_parameters.count(stringf("\\_TECHMAP_WIREINIT_%s_", log_id(conn.first))) != 0) {
-							auto sig = sigmap(conn.second);
-							RTLIL::Const value(State::Sx, sig.size());
-							for (int i = 0; i < sig.size(); i++) {
-								auto it = init_bits.find(sig[i]);
-								if (it != init_bits.end()) {
-									value[i] = it->second;
-								}
+				if (tpl->avail_parameters.count(ID::_TECHMAP_CELLTYPE_) != 0)
+					parameters.emplace(ID::_TECHMAP_CELLTYPE_, RTLIL::unescape_id(cell->type));
+
+				for (auto &conn : cell->connections()) {
+					if (tpl->avail_parameters.count(stringf("\\_TECHMAP_CONSTMSK_%s_", log_id(conn.first))) != 0) {
+						std::vector<RTLIL::SigBit> v = sigmap(conn.second).to_sigbit_vector();
+						for (auto &bit : v)
+							bit = RTLIL::SigBit(bit.wire == nullptr ? RTLIL::State::S1 : RTLIL::State::S0);
+						parameters.emplace(stringf("\\_TECHMAP_CONSTMSK_%s_", log_id(conn.first)), RTLIL::SigSpec(v).as_const());
+					}
+					if (tpl->avail_parameters.count(stringf("\\_TECHMAP_CONSTVAL_%s_", log_id(conn.first))) != 0) {
+						std::vector<RTLIL::SigBit> v = sigmap(conn.second).to_sigbit_vector();
+						for (auto &bit : v)
+							if (bit.wire != nullptr)
+								bit = RTLIL::SigBit(RTLIL::State::Sx);
+						parameters.emplace(stringf("\\_TECHMAP_CONSTVAL_%s_", log_id(conn.first)), RTLIL::SigSpec(v).as_const());
+					}
+					if (tpl->avail_parameters.count(stringf("\\_TECHMAP_WIREINIT_%s_", log_id(conn.first))) != 0) {
+						auto sig = sigmap(conn.second);
+						RTLIL::Const value(State::Sx, sig.size());
+						for (int i = 0; i < sig.size(); i++) {
+							auto it = init_bits.find(sig[i]);
+							if (it != init_bits.end()) {
+								value[i] = it->second;
 							}
-							parameters.emplace(stringf("\\_TECHMAP_WIREINIT_%s_", log_id(conn.first)), value);
 						}
+						parameters.emplace(stringf("\\_TECHMAP_WIREINIT_%s_", log_id(conn.first)), value);
 					}
+				}
 
+				{
 					int unique_bit_id_counter = 0;
 					dict<RTLIL::SigBit, int> unique_bit_id;
 					unique_bit_id[RTLIL::State::S0] = unique_bit_id_counter++;
@@ -787,13 +728,9 @@ struct TechmapWorker
 					}
 				}
 
-				if (flatten_mode) {
-					techmap_do_cache[tpl] = true;
-				} else {
-					RTLIL::Module *constmapped_tpl = map->module(constmap_tpl_name(sigmap, tpl, cell, false));
-					if (constmapped_tpl != nullptr)
-						tpl = constmapped_tpl;
-				}
+				RTLIL::Module *constmapped_tpl = map->module(constmap_tpl_name(sigmap, tpl, cell, false));
+				if (constmapped_tpl != nullptr)
+					tpl = constmapped_tpl;
 
 				if (techmap_do_cache.count(tpl) == 0)
 				{
@@ -1333,97 +1270,4 @@ struct TechmapPass : public Pass {
 	}
 } TechmapPass;
 
-struct FlattenPass : public Pass {
-	FlattenPass() : Pass("flatten", "flatten design") { }
-	void help() YS_OVERRIDE
-	{
-		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
-		log("\n");
-		log("    flatten [options] [selection]\n");
-		log("\n");
-		log("This pass flattens the design by replacing cells by their implementation. This\n");
-		log("pass is very similar to the 'techmap' pass. The only difference is that this\n");
-		log("pass is using the current design as mapping library.\n");
-		log("\n");
-		log("Cells and/or modules with the 'keep_hierarchy' attribute set will not be\n");
-		log("flattened by this command.\n");
-		log("\n");
-		log("    -wb\n");
-		log("        Ignore the 'whitebox' attribute on cell implementations.\n");
-		log("\n");
-	}
-	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
-	{
-		log_header(design, "Executing FLATTEN pass (flatten design).\n");
-		log_push();
-
-		TechmapWorker worker;
-		worker.flatten_mode = true;
-
-		size_t argidx;
-		for (argidx = 1; argidx < args.size(); argidx++) {
-			if (args[argidx] == "-wb") {
-				worker.ignore_wb = true;
-				continue;
-			}
-			break;
-		}
-		extra_args(args, argidx, design);
-
-
-		dict<IdString, pool<IdString>> celltypeMap;
-		for (auto module : design->modules())
-			celltypeMap[module->name].insert(module->name);
-		for (auto &i : celltypeMap)
-			i.second.sort(RTLIL::sort_by_id_str());
-
-		RTLIL::Module *top_mod = nullptr;
-		if (design->full_selection())
-			for (auto mod : design->modules())
-				if (mod->get_bool_attribute(ID::top))
-					top_mod = mod;
-
-		pool<RTLIL::Cell*> handled_cells;
-		if (top_mod != nullptr) {
-			worker.flatten_do_list.insert(top_mod->name);
-			while (!worker.flatten_do_list.empty()) {
-				auto mod = design->module(*worker.flatten_do_list.begin());
-				while (worker.techmap_module(design, mod, design, handled_cells, celltypeMap, false)) { }
-				worker.flatten_done_list.insert(mod->name);
-				worker.flatten_do_list.erase(mod->name);
-			}
-		} else {
-			for (auto mod : design->modules().to_vector())
-				while (worker.techmap_module(design, mod, design, handled_cells, celltypeMap, false)) { }
-		}
-
-		log_suppressed();
-		log("No more expansions possible.\n");
-
-		if (top_mod != nullptr)
-		{
-			pool<IdString> used_modules, new_used_modules;
-			new_used_modules.insert(top_mod->name);
-			while (!new_used_modules.empty()) {
-				pool<IdString> queue;
-				queue.swap(new_used_modules);
-				for (auto modname : queue)
-					used_modules.insert(modname);
-				for (auto modname : queue)
-					for (auto cell : design->module(modname)->cells())
-						if (design->module(cell->type) && !used_modules[cell->type])
-							new_used_modules.insert(cell->type);
-			}
-
-			for (auto mod : design->modules().to_vector())
-				if (!used_modules[mod->name] && !mod->get_blackbox_attribute(worker.ignore_wb)) {
-					log("Deleting now unused module %s.\n", log_id(mod));
-					design->remove(mod);
-				}
-		}
-
-		log_pop();
-	}
-} FlattenPass;
-
 PRIVATE_NAMESPACE_END