diff --git a/Makefile b/Makefile
index 4d1a94bc2..1a5d8a093 100644
--- a/Makefile
+++ b/Makefile
@@ -890,6 +890,7 @@ MK_TEST_DIRS += tests/sim
 MK_TEST_DIRS += tests/svtypes
 MK_TEST_DIRS += tests/techmap
 MK_TEST_DIRS += tests/various
+MK_TEST_DIRS += tests/rtlil
 ifeq ($(ENABLE_VERIFIC),1)
 ifneq ($(YOSYS_NOVERIFIC),1)
 MK_TEST_DIRS += tests/verific
diff --git a/backends/rtlil/rtlil_backend.cc b/backends/rtlil/rtlil_backend.cc
index cb17432b1..d607be837 100644
--- a/backends/rtlil/rtlil_backend.cc
+++ b/backends/rtlil/rtlil_backend.cc
@@ -24,12 +24,23 @@
 
 #include "rtlil_backend.h"
 #include "kernel/yosys.h"
+#include "kernel/utils.h"
 #include <errno.h>
+#include <iterator>
 
 USING_YOSYS_NAMESPACE
 using namespace RTLIL_BACKEND;
 YOSYS_NAMESPACE_BEGIN
 
+void RTLIL_BACKEND::dump_attributes(std::ostream &f, std::string indent, const RTLIL::AttrObject *obj)
+{
+	for (const auto& [name, value] : reversed(obj->attributes)) {
+		f << stringf("%s" "attribute %s ", indent, name);
+		dump_const(f, value);
+		f << stringf("\n");
+	}
+}
+
 void RTLIL_BACKEND::dump_const(std::ostream &f, const RTLIL::Const &data, int width, int offset, bool autoint)
 {
 	if (width < 0)
@@ -110,8 +121,8 @@ void RTLIL_BACKEND::dump_sigspec(std::ostream &f, const RTLIL::SigSpec &sig, boo
 		dump_sigchunk(f, sig.as_chunk(), autoint);
 	} else {
 		f << stringf("{ ");
-		for (auto it = sig.chunks().rbegin(); it != sig.chunks().rend(); ++it) {
-			dump_sigchunk(f, *it, false);
+		for (const auto& chunk : reversed(sig.chunks())) {
+			dump_sigchunk(f, chunk, false);
 			f << stringf(" ");
 		}
 		f << stringf("}");
@@ -120,14 +131,10 @@ void RTLIL_BACKEND::dump_sigspec(std::ostream &f, const RTLIL::SigSpec &sig, boo
 
 void RTLIL_BACKEND::dump_wire(std::ostream &f, std::string indent, const RTLIL::Wire *wire)
 {
-	for (auto &it : wire->attributes) {
-		f << stringf("%s" "attribute %s ", indent, it.first);
-		dump_const(f, it.second);
-		f << stringf("\n");
-	}
+	dump_attributes(f, indent, wire);
 	if (wire->driverCell_) {
 		f << stringf("%s" "# driver %s %s\n", indent,
-				wire->driverCell()->name.c_str(), wire->driverPort().c_str());
+				wire->driverCell()->name, wire->driverPort());
 	}
 	f << stringf("%s" "wire ", indent);
 	if (wire->width != 1)
@@ -149,11 +156,7 @@ void RTLIL_BACKEND::dump_wire(std::ostream &f, std::string indent, const RTLIL::
 
 void RTLIL_BACKEND::dump_memory(std::ostream &f, std::string indent, const RTLIL::Memory *memory)
 {
-	for (auto &it : memory->attributes) {
-		f << stringf("%s" "attribute %s ", indent, it.first);
-		dump_const(f, it.second);
-		f << stringf("\n");
-	}
+	dump_attributes(f, indent, memory);
 	f << stringf("%s" "memory ", indent);
 	if (memory->width != 1)
 		f << stringf("width %d ", memory->width);
@@ -166,23 +169,19 @@ void RTLIL_BACKEND::dump_memory(std::ostream &f, std::string indent, const RTLIL
 
 void RTLIL_BACKEND::dump_cell(std::ostream &f, std::string indent, const RTLIL::Cell *cell)
 {
-	for (auto &it : cell->attributes) {
-		f << stringf("%s" "attribute %s ", indent, it.first);
-		dump_const(f, it.second);
-		f << stringf("\n");
-	}
+	dump_attributes(f, indent, cell);
 	f << stringf("%s" "cell %s %s\n", indent, cell->type, cell->name);
-	for (auto &it : cell->parameters) {
+	for (const auto& [name, param] : reversed(cell->parameters)) {
 		f << stringf("%s  parameter%s%s %s ", indent,
-				(it.second.flags & RTLIL::CONST_FLAG_SIGNED) != 0 ? " signed" : "",
-				(it.second.flags & RTLIL::CONST_FLAG_REAL) != 0 ? " real" : "",
-				it.first.c_str());
-		dump_const(f, it.second);
+				(param.flags & RTLIL::CONST_FLAG_SIGNED) != 0 ? " signed" : "",
+				(param.flags & RTLIL::CONST_FLAG_REAL) != 0 ? " real" : "",
+				name);
+		dump_const(f, param);
 		f << stringf("\n");
 	}
-	for (auto &it : cell->connections()) {
-		f << stringf("%s  connect %s ", indent, it.first);
-		dump_sigspec(f, it.second);
+	for (const auto& [port, sig] : reversed(cell->connections_)) {
+		f << stringf("%s  connect %s ", indent, port);
+		dump_sigspec(f, sig);
 		f << stringf("\n");
 	}
 	f << stringf("%s" "end\n", indent);
@@ -190,47 +189,38 @@ void RTLIL_BACKEND::dump_cell(std::ostream &f, std::string indent, const RTLIL::
 
 void RTLIL_BACKEND::dump_proc_case_body(std::ostream &f, std::string indent, const RTLIL::CaseRule *cs)
 {
-	for (auto it = cs->actions.begin(); it != cs->actions.end(); ++it)
-	{
+	for (const auto& [lhs, rhs] : cs->actions) {
 		f << stringf("%s" "assign ", indent);
-		dump_sigspec(f, it->first);
+		dump_sigspec(f, lhs);
 		f << stringf(" ");
-		dump_sigspec(f, it->second);
+		dump_sigspec(f, rhs);
 		f << stringf("\n");
 	}
 
-	for (auto it = cs->switches.begin(); it != cs->switches.end(); ++it)
-		dump_proc_switch(f, indent, *it);
+	for (const auto& sw : cs->switches)
+		dump_proc_switch(f, indent, sw);
 }
 
 void RTLIL_BACKEND::dump_proc_switch(std::ostream &f, std::string indent, const RTLIL::SwitchRule *sw)
 {
-	for (auto it = sw->attributes.begin(); it != sw->attributes.end(); ++it) {
-		f << stringf("%s" "attribute %s ", indent, it->first);
-		dump_const(f, it->second);
-		f << stringf("\n");
-	}
+	dump_attributes(f, indent, sw);
 
 	f << stringf("%s" "switch ", indent);
 	dump_sigspec(f, sw->signal);
 	f << stringf("\n");
 
-	for (auto it = sw->cases.begin(); it != sw->cases.end(); ++it)
+	for (const auto case_ : sw->cases)
 	{
-		for (auto ait = (*it)->attributes.begin(); ait != (*it)->attributes.end(); ++ait) {
-			f << stringf("%s  attribute %s ", indent, ait->first);
-			dump_const(f, ait->second);
-			f << stringf("\n");
-		}
+		dump_attributes(f, indent, case_);
 		f << stringf("%s  case ", indent);
-		for (size_t i = 0; i < (*it)->compare.size(); i++) {
+		for (size_t i = 0; i < case_->compare.size(); i++) {
 			if (i > 0)
 				f << stringf(" , ");
-			dump_sigspec(f, (*it)->compare[i]);
+			dump_sigspec(f, case_->compare[i]);
 		}
 		f << stringf("\n");
 
-		dump_proc_case_body(f, indent + "    ", *it);
+		dump_proc_case_body(f, indent + "    ", case_);
 	}
 
 	f << stringf("%s" "end\n", indent);
@@ -253,20 +243,16 @@ void RTLIL_BACKEND::dump_proc_sync(std::ostream &f, std::string indent, const RT
 	case RTLIL::STi: f << stringf("init\n"); break;
 	}
 
-	for (auto &it: sy->actions) {
+	for (const auto& [lhs, rhs] : sy->actions) {
 		f << stringf("%s  update ", indent);
-		dump_sigspec(f, it.first);
+		dump_sigspec(f, lhs);
 		f << stringf(" ");
-		dump_sigspec(f, it.second);
+		dump_sigspec(f, rhs);
 		f << stringf("\n");
 	}
 
 	for (auto &it: sy->mem_write_actions) {
-		for (auto it2 = it.attributes.begin(); it2 != it.attributes.end(); ++it2) {
-			f << stringf("%s  attribute %s ", indent, it2->first);
-			dump_const(f, it2->second);
-			f << stringf("\n");
-		}
+		dump_attributes(f, indent, &it);
 		f << stringf("%s  memwr %s ", indent, it.memid);
 		dump_sigspec(f, it.address);
 		f << stringf(" ");
@@ -281,15 +267,11 @@ void RTLIL_BACKEND::dump_proc_sync(std::ostream &f, std::string indent, const RT
 
 void RTLIL_BACKEND::dump_proc(std::ostream &f, std::string indent, const RTLIL::Process *proc)
 {
-	for (auto it = proc->attributes.begin(); it != proc->attributes.end(); ++it) {
-		f << stringf("%s" "attribute %s ", indent, it->first);
-		dump_const(f, it->second);
-		f << stringf("\n");
-	}
+	dump_attributes(f, indent, proc);
 	f << stringf("%s" "process %s\n", indent, proc->name);
 	dump_proc_case_body(f, indent + "  ", &proc->root_case);
-	for (auto it = proc->syncs.begin(); it != proc->syncs.end(); ++it)
-		dump_proc_sync(f, indent + "  ", *it);
+	for (auto* sync : proc->syncs)
+		dump_proc_sync(f, indent + "  ", sync);
 	f << stringf("%s" "end\n", indent);
 }
 
@@ -309,11 +291,7 @@ void RTLIL_BACKEND::dump_module(std::ostream &f, std::string indent, RTLIL::Modu
 
 	if (print_header)
 	{
-		for (auto it = module->attributes.begin(); it != module->attributes.end(); ++it) {
-			f << stringf("%s" "attribute %s ", indent, it->first);
-			dump_const(f, it->second);
-			f << stringf("\n");
-		}
+		dump_attributes(f, indent, module);
 
 		f << stringf("%s" "module %s\n", indent, module->name);
 
@@ -335,40 +313,40 @@ void RTLIL_BACKEND::dump_module(std::ostream &f, std::string indent, RTLIL::Modu
 
 	if (print_body)
 	{
-		for (auto it : module->wires())
-			if (!only_selected || design->selected(module, it)) {
+		for (const auto& [_, wire] : reversed(module->wires_))
+			if (!only_selected || design->selected(module, wire)) {
 				if (only_selected)
 					f << stringf("\n");
-				dump_wire(f, indent + "  ", it);
+				dump_wire(f, indent + "  ", wire);
 			}
 
-		for (auto it : module->memories)
-			if (!only_selected || design->selected(module, it.second)) {
+		for (const auto& [_, mem] : reversed(module->memories))
+			if (!only_selected || design->selected(module, mem)) {
 				if (only_selected)
 					f << stringf("\n");
-				dump_memory(f, indent + "  ", it.second);
+				dump_memory(f, indent + "  ", mem);
 			}
 
-		for (auto it : module->cells())
-			if (!only_selected || design->selected(module, it)) {
+		for (const auto& [_, cell] : reversed(module->cells_))
+			if (!only_selected || design->selected(module, cell)) {
 				if (only_selected)
 					f << stringf("\n");
-				dump_cell(f, indent + "  ", it);
+				dump_cell(f, indent + "  ", cell);
 			}
 
-		for (auto it : module->processes)
-			if (!only_selected || design->selected(module, it.second)) {
+		for (const auto& [_, process] : reversed(module->processes))
+			if (!only_selected || design->selected(module, process)) {
 				if (only_selected)
 					f << stringf("\n");
-				dump_proc(f, indent + "  ", it.second);
+				dump_proc(f, indent + "  ", process);
 			}
 
 		bool first_conn_line = true;
-		for (auto it = module->connections().begin(); it != module->connections().end(); ++it) {
+		for (const auto& [lhs, rhs] : module->connections()) {
 			bool show_conn = !only_selected || design->selected_whole_module(module->name);
 			if (!show_conn) {
-				RTLIL::SigSpec sigs = it->first;
-				sigs.append(it->second);
+				RTLIL::SigSpec sigs = lhs;
+				sigs.append(rhs);
 				for (auto &c : sigs.chunks()) {
 					if (c.wire == NULL || !design->selected(module, c.wire))
 						continue;
@@ -378,7 +356,7 @@ void RTLIL_BACKEND::dump_module(std::ostream &f, std::string indent, RTLIL::Modu
 			if (show_conn) {
 				if (only_selected && first_conn_line)
 					f << stringf("\n");
-				dump_conn(f, indent + "  ", it->first, it->second);
+				dump_conn(f, indent + "  ", lhs, rhs);
 				first_conn_line = false;
 			}
 		}
@@ -394,7 +372,7 @@ void RTLIL_BACKEND::dump_design(std::ostream &f, RTLIL::Design *design, bool onl
 
 	if (!flag_m) {
 		int count_selected_mods = 0;
-		for (auto module : design->modules()) {
+		for (auto* module : design->modules()) {
 			if (design->selected_whole_module(module->name))
 				flag_m = true;
 			if (design->selected(module))
@@ -410,7 +388,7 @@ void RTLIL_BACKEND::dump_design(std::ostream &f, RTLIL::Design *design, bool onl
 		f << stringf("autoidx %d\n", autoidx);
 	}
 
-	for (auto module : design->modules()) {
+	for (const auto& [_, module] : reversed(design->modules_)) {
 		if (!only_selected || design->selected(module)) {
 			if (only_selected)
 				f << stringf("\n");
@@ -438,10 +416,14 @@ struct RTLILBackend : public Backend {
 		log("    -selected\n");
 		log("        only write selected parts of the design.\n");
 		log("\n");
+		log("    -sort\n");
+		log("        sort design in-place (used to be default).\n");
+		log("\n");
 	}
 	void execute(std::ostream *&f, std::string filename, std::vector<std::string> args, RTLIL::Design *design) override
 	{
 		bool selected = false;
+		bool do_sort = false;
 
 		log_header(design, "Executing RTLIL backend.\n");
 
@@ -452,14 +434,19 @@ struct RTLILBackend : public Backend {
 				selected = true;
 				continue;
 			}
+			if (arg == "-sort") {
+				do_sort = true;
+				continue;
+			}
 			break;
 		}
 		extra_args(f, filename, args, argidx);
 
-		design->sort();
-
 		log("Output filename: %s\n", filename);
 
+		if (do_sort)
+			design->sort();
+
 		*f << stringf("# Generated by %s\n", yosys_maybe_version());
 		RTLIL_BACKEND::dump_design(*f, design, selected, true, false);
 	}
@@ -528,7 +515,7 @@ struct DumpPass : public Pass {
 		if (!empty) {
 			rewrite_filename(filename);
 			std::ofstream *ff = new std::ofstream;
-			ff->open(filename.c_str(), append ? std::ofstream::app : std::ofstream::trunc);
+			ff->open(filename, append ? std::ofstream::app : std::ofstream::trunc);
 			if (ff->fail()) {
 				delete ff;
 				log_error("Can't open file `%s' for writing: %s\n", filename, strerror(errno));
diff --git a/backends/rtlil/rtlil_backend.h b/backends/rtlil/rtlil_backend.h
index 35829729c..dd7347def 100644
--- a/backends/rtlil/rtlil_backend.h
+++ b/backends/rtlil/rtlil_backend.h
@@ -31,6 +31,7 @@
 YOSYS_NAMESPACE_BEGIN
 
 namespace RTLIL_BACKEND {
+	void dump_attributes(std::ostream &f, std::string indent, const RTLIL::AttrObject *obj);
 	void dump_const(std::ostream &f, const RTLIL::Const &data, int width = -1, int offset = 0, bool autoint = true);
 	void dump_sigchunk(std::ostream &f, const RTLIL::SigChunk &chunk, bool autoint = true);
 	void dump_sigspec(std::ostream &f, const RTLIL::SigSpec &sig, bool autoint = true);
diff --git a/frontends/verilog/verilog_frontend.cc b/frontends/verilog/verilog_frontend.cc
index 2bdaf40ce..6c9e67dc5 100644
--- a/frontends/verilog/verilog_frontend.cc
+++ b/frontends/verilog/verilog_frontend.cc
@@ -229,6 +229,10 @@ struct VerilogFrontend : public Frontend {
 		log("        add 'dir' to the directories which are used when searching include\n");
 		log("        files\n");
 		log("\n");
+		log("    -relativeshare\n");
+		log("        use paths relative to share directory for source locations\n");
+		log("        where possible (experimental).\n");
+		log("\n");
 		log("The command 'verilog_defaults' can be used to register default options for\n");
 		log("subsequent calls to 'read_verilog'.\n");
 		log("\n");
@@ -273,6 +277,7 @@ struct VerilogFrontend : public Frontend {
 		bool flag_nowb = false;
 		bool flag_nosynthesis = false;
 		bool flag_yydebug = false;
+		bool flag_relative_share = false;
 		define_map_t defines_map;
 
 		std::list<std::string> include_dirs;
@@ -450,6 +455,11 @@ struct VerilogFrontend : public Frontend {
 				attributes.push_back(RTLIL::escape_id(args[++argidx]));
 				continue;
 			}
+			if (arg == "-relativeshare") {
+				flag_relative_share = true;
+				log_experimental("read_verilog -relativeshare");
+				continue;
+			}
 			if (arg == "-D" && argidx+1 < args.size()) {
 				std::string name = args[++argidx], value;
 				size_t equal = name.find('=');
@@ -490,6 +500,13 @@ struct VerilogFrontend : public Frontend {
 		log("Parsing %s%s input from `%s' to AST representation.\n",
 				parse_mode.formal ? "formal " : "", parse_mode.sv ? "SystemVerilog" : "Verilog", filename.c_str());
 
+		log("verilog frontend filename %s\n", filename.c_str());
+		if (flag_relative_share) {
+			auto share_path = proc_share_dirname();
+			if (filename.substr(0, share_path.length()) == share_path)
+				filename = std::string("+/") + filename.substr(share_path.length());
+			log("new filename %s\n", filename.c_str());
+		}
 		AST::sv_mode_but_global_and_used_for_literally_one_condition = parse_mode.sv;
 		std::string code_after_preproc;
 
diff --git a/kernel/hashlib.h b/kernel/hashlib.h
index c95ce1e7b..ed329bba6 100644
--- a/kernel/hashlib.h
+++ b/kernel/hashlib.h
@@ -569,13 +569,16 @@ public:
 		int index;
 		const_iterator(const dict *ptr, int index) : ptr(ptr), index(index) { }
 	public:
-		typedef std::forward_iterator_tag iterator_category;
+		typedef std::bidirectional_iterator_tag iterator_category;
 		typedef std::pair<K, T> value_type;
 		typedef ptrdiff_t difference_type;
-		typedef std::pair<K, T>* pointer;
-		typedef std::pair<K, T>& reference;
+		typedef const std::pair<K, T>* pointer;
+		typedef const std::pair<K, T>& reference;
 		const_iterator() { }
 		const_iterator operator++() { index--; return *this; }
+		const_iterator operator++(int) { const_iterator tmp = *this; index--; return tmp; }
+		const_iterator operator--() { index++; return *this; }
+		const_iterator operator--(int) { const_iterator tmp = *this; index++; return tmp; }
 		const_iterator operator+=(int amt) { index -= amt; return *this; }
 		bool operator<(const const_iterator &other) const { return index > other.index; }
 		bool operator==(const const_iterator &other) const { return index == other.index; }
@@ -609,6 +612,13 @@ public:
 		const std::pair<K, T> *operator->() const { return &ptr->entries[index].udata; }
 		operator const_iterator() const { return const_iterator(ptr, index); }
 	};
+	using reverse_iterator = std::reverse_iterator<const_iterator>;
+	reverse_iterator rbegin() const {
+		return std::make_reverse_iterator(end());
+	}
+	reverse_iterator rend() const {
+		return std::make_reverse_iterator(begin());
+	}
 
 	constexpr dict()
 	{
@@ -858,7 +868,7 @@ public:
 
 	const_iterator begin() const { return const_iterator(this, int(entries.size())-1); }
 	const_iterator element(int n) const { return const_iterator(this, int(entries.size())-1-n); }
-	const_iterator end() const { return const_iterator(nullptr, -1); }
+	const_iterator end() const { return const_iterator(this, -1); }
 };
 
 template<typename K, typename OPS>
diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index 4f34d6f7b..7d53fdd32 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -5888,6 +5888,7 @@ RTLIL::CaseRule *RTLIL::CaseRule::clone() const
 	RTLIL::CaseRule *new_caserule = new RTLIL::CaseRule;
 	new_caserule->compare = compare;
 	new_caserule->actions = actions;
+	new_caserule->attributes = attributes;
 	for (auto &it : switches)
 		new_caserule->switches.push_back(it->clone());
 	return new_caserule;
diff --git a/kernel/utils.h b/kernel/utils.h
index 6c9fe36a5..5c739aceb 100644
--- a/kernel/utils.h
+++ b/kernel/utils.h
@@ -21,6 +21,7 @@
 // do not depend on any other components of yosys (except stuff like log_*).
 
 #include "kernel/yosys.h"
+#include <iterator>
 
 #ifndef UTILS_H
 #define UTILS_H
@@ -276,6 +277,16 @@ inline int ceil_log2(int x)
 #endif
 }
 
+template <typename T>
+auto reversed(const T& container) {
+    struct reverse_view {
+        const T& cont;
+        auto begin() const { return cont.rbegin(); }
+        auto end() const { return cont.rend(); }
+    };
+    return reverse_view{container};
+}
+
 YOSYS_NAMESPACE_END
 
 #endif
diff --git a/passes/cmds/bugpoint.cc b/passes/cmds/bugpoint.cc
index 8432c27fd..897dd8459 100644
--- a/passes/cmds/bugpoint.cc
+++ b/passes/cmds/bugpoint.cc
@@ -122,8 +122,6 @@ struct BugpointPass : public Pass {
 
 	int run_yosys(RTLIL::Design *design, string runner, string yosys_cmd, string yosys_arg, string suffix, bool catch_err)
 	{
-		design->sort();
-
 		string bugpoint_file = "bugpoint-case";
 		if (suffix.size())
 			bugpoint_file += stringf(".%.8s", suffix);
diff --git a/passes/techmap/techmap.cc b/passes/techmap/techmap.cc
index 30b8e17ab..281a8795a 100644
--- a/passes/techmap/techmap.cc
+++ b/passes/techmap/techmap.cc
@@ -1032,6 +1032,10 @@ struct TechmapPass : public Pass {
 		log("    -dont_map <celltype>\n");
 		log("        leave the given cell type unmapped by ignoring any mapping rules for it\n");
 		log("\n");
+		log("    -relativeshare\n");
+		log("        use paths relative to share directory for source locations\n");
+		log("        where possible (experimental).\n");
+		log("\n");
 		log("When a module in the map file has the 'techmap_celltype' attribute set, it will\n");
 		log("match cells with a type that match the text value of this attribute. Otherwise\n");
 		log("the module name will be used to match the cell.  Multiple space-separated cell\n");
@@ -1185,6 +1189,11 @@ struct TechmapPass : public Pass {
 				verilog_frontend += " -I " + args[++argidx];
 				continue;
 			}
+			if (args[argidx] == "-relativeshare") {
+				verilog_frontend += " -relativeshare";
+				log_experimental("techmap -relativeshare");
+				continue;
+			}
 			if (args[argidx] == "-assert") {
 				worker.assert_mode = true;
 				continue;
diff --git a/passes/tests/raise_error.cc b/passes/tests/raise_error.cc
index 7233e78fa..b21ec7d1d 100644
--- a/passes/tests/raise_error.cc
+++ b/passes/tests/raise_error.cc
@@ -47,7 +47,7 @@ struct RaiseErrorPass : public Pass {
 		extra_args(args, argidx, design, true);
 
 		RTLIL::NamedObject *err_obj = nullptr;
-		
+
 		for (auto mod : design->all_selected_modules()) {
 			if (mod->has_attribute(ID::raise_error)) {
 				err_obj = mod->clone();
diff --git a/techlibs/common/synth.cc b/techlibs/common/synth.cc
index 9c85fbbc7..0dbb7cbec 100644
--- a/techlibs/common/synth.cc
+++ b/techlibs/common/synth.cc
@@ -98,13 +98,17 @@ struct SynthPass : public ScriptPass {
 		log("        mapping library in the `techmap` step. this option can be\n");
 		log("        repeated.\n");
 		log("\n");
+		log("    -relativeshare\n");
+		log("        use paths relative to share directory for source locations\n");
+		log("        where possible (experimental).\n");
+		log("\n");
 		log("The following commands are executed by this synthesis command:\n");
 		help_script();
 		log("\n");
 	}
 
 	string top_module, fsm_opts, memory_opts, abc;
-	bool autotop, flatten, noalumacc, nofsm, noabc, noshare, flowmap, booth, hieropt;
+	bool autotop, flatten, noalumacc, nofsm, noabc, noshare, flowmap, booth, hieropt, relative_share;
 	int lut;
 	std::vector<std::string> techmap_maps;
 
@@ -124,6 +128,7 @@ struct SynthPass : public ScriptPass {
 		flowmap = false;
 		booth = false;
 		hieropt = false;
+		relative_share = false;
 		abc = "abc";
 		techmap_maps.clear();
 	}
@@ -211,6 +216,11 @@ struct SynthPass : public ScriptPass {
 				hieropt = true;
 				continue;
 			}
+			if (args[argidx] == "-relativeshare") {
+				relative_share = true;
+				log_experimental("synth -relativeshare");
+				continue;
+			}
 			break;
 		}
 		extra_args(args, argidx, design);
@@ -239,6 +249,10 @@ struct SynthPass : public ScriptPass {
 		else
 			hieropt_flag = hieropt ? " -hier" : "";
 
+		std::string techmap_cmd = "techmap";
+		if (relative_share)
+			techmap_cmd += " -relativeshare";
+
 		if (check_label("begin")) {
 			if (help_mode) {
 				run("hierarchy -check [-top <top> | -auto-top]");
@@ -268,9 +282,9 @@ struct SynthPass : public ScriptPass {
 			run("peepopt");
 			run("opt_clean");
 			if (help_mode)
-				run("techmap -map +/cmp2lut.v -map +/cmp2lcu.v", " (if -lut)");
+				run(techmap_cmd + " -map +/cmp2lut.v -map +/cmp2lcu.v", " (if -lut)");
 			else if (lut)
-				run(stringf("techmap -map +/cmp2lut.v -map +/cmp2lcu.v -D LUT_WIDTH=%d", lut));
+				run(stringf("%s -map +/cmp2lut.v -map +/cmp2lcu.v -D LUT_WIDTH=%d", techmap_cmd, lut));
 			if (booth || help_mode)
 				run("booth", "    (if -booth)");
 			if (!noalumacc)
@@ -287,22 +301,22 @@ struct SynthPass : public ScriptPass {
 			run("memory_map");
 			run("opt -full");
 			if (help_mode) {
-				run("techmap", "                  (unless -extra-map)");	
-				run("techmap -map +/techmap.v -map <inject>", "  (if -extra-map)");
+				run(techmap_cmd, "                  (unless -extra-map)");	
+				run(techmap_cmd + " -map +/techmap.v -map <inject>", "  (if -extra-map)");
 			} else {
 				std::string techmap_opts;
 				if (!techmap_maps.empty())
 					techmap_opts += " -map +/techmap.v";
 				for (auto fn : techmap_maps)
 					techmap_opts += stringf(" -map %s", fn);
-				run("techmap" + techmap_opts);
+				run(techmap_cmd + techmap_opts);
 			}
 			if (help_mode) {
-				run("techmap -map +/gate2lut.v", "(if -noabc and -lut)");
+				run(techmap_cmd + " -map +/gate2lut.v", "(if -noabc and -lut)");
 				run("clean; opt_lut", "           (if -noabc and -lut)");
 				run("flowmap -maxlut K", "        (if -flowmap and -lut)");
 			} else if (noabc && lut) {
-				run(stringf("techmap -map +/gate2lut.v -D LUT_WIDTH=%d", lut));
+				run(stringf("%s -map +/gate2lut.v -D LUT_WIDTH=%d", techmap_cmd, lut));
 				run("clean; opt_lut");
 			} else if (flowmap) {
 				run(stringf("flowmap -maxlut %d", lut));
diff --git a/techlibs/fabulous/synth_fabulous.cc b/techlibs/fabulous/synth_fabulous.cc
index 3b95ff91e..f74dc8e26 100644
--- a/techlibs/fabulous/synth_fabulous.cc
+++ b/techlibs/fabulous/synth_fabulous.cc
@@ -69,7 +69,7 @@ struct SynthPass : public ScriptPass
 		log("        use the specified Verilog file for extra primitives (can be specified multiple\n");
 		log("        times).\n");
 		log("\n");
-		log("    -extra-map <techamp.v>\n");
+		log("    -extra-map <techmap.v>\n");
 		log("        use the specified Verilog file for extra techmap rules (can be specified multiple\n");
 		log("        times).\n");
 		log("\n");
diff --git a/tests/bugpoint/raise_error.ys b/tests/bugpoint/raise_error.ys
index 8fb10eb96..79127deff 100644
--- a/tests/bugpoint/raise_error.ys
+++ b/tests/bugpoint/raise_error.ys
@@ -22,34 +22,37 @@ logger -check-expected
 
 # raise_error with int exits with status
 design -load read
+setattr -mod -unset raise_error def other
+dump
 bugpoint -suffix error -yosys ../../yosys -command raise_error -expect-return 7
 select -assert-mod-count 1 =*
 select -assert-mod-count 1 top
 
 # raise_error -always still uses 'raise_error' attribute if possible
 design -load read
+setattr -mod -unset raise_error def other
 bugpoint -suffix error -yosys ../../yosys -command "raise_error -always" -expect-return 7
 select -assert-mod-count 1 =*
 select -assert-mod-count 1 top
 
 # raise_error with string prints message and exits with 1
 design -load read
-rename top abc
+setattr -mod -unset raise_error top def
 bugpoint -suffix error -yosys ../../yosys -command raise_error -grep "help me" -expect-return 1
 select -assert-mod-count 1 =*
 select -assert-mod-count 1 other
 
 # raise_error with no value exits with 1
 design -load read
-rename def zzy
+setattr -mod -unset raise_error top
 delete other
 bugpoint -suffix error -yosys ../../yosys -command raise_error -expect-return 1
 select -assert-mod-count 1 =*
-select -assert-mod-count 1 zzy
+select -assert-mod-count 1 def
 
 # raise_error -stderr prints to stderr and exits with 1
 design -load read
-rename top abc
+setattr -mod -unset raise_error top def
 bugpoint -suffix error -yosys ../../yosys -command "raise_error -stderr" -err-grep "help me" -expect-return 1
 select -assert-mod-count 1 =*
 select -assert-mod-count 1 other
diff --git a/tests/functional/test_functional.py b/tests/functional/test_functional.py
index 7a09966d8..e4c78a1fb 100644
--- a/tests/functional/test_functional.py
+++ b/tests/functional/test_functional.py
@@ -24,7 +24,7 @@ def compile_cpp(in_path, out_path, args):
     run(['g++', '-g', '-std=c++17'] + args + [str(in_path), '-o', str(out_path)])
 
 def yosys_synth(verilog_file, rtlil_file):
-    yosys(f"read_verilog {quote(verilog_file)} ; prep ; write_rtlil {quote(rtlil_file)}")
+    yosys(f"read_verilog {quote(verilog_file)} ; prep ; setundef -undriven -undef ; write_rtlil {quote(rtlil_file)}")
 
 # simulate an rtlil file with yosys, comparing with a given vcd file, and writing out the yosys simulation results into a second vcd file
 def yosys_sim(rtlil_file, vcd_reference_file, vcd_out_file, preprocessing = ""):
@@ -91,4 +91,4 @@ def test_print_graph(tmp_path):
     tb_file = base_path / 'tests/functional/picorv32_tb.v'
     cpu_file = base_path / 'tests/functional/picorv32.v'
     # currently we only check that we can print the graph without getting an error, not that it prints anything sensibl
-    yosys(f"read_verilog {quote(tb_file)} {quote(cpu_file)}; prep -top gold; flatten; clk2fflogic; test_generic")
+    yosys(f"read_verilog {quote(tb_file)} {quote(cpu_file)}; prep -top gold; setundef -undriven -undef ; flatten; clk2fflogic; test_generic")
diff --git a/tests/rtlil/.gitignore b/tests/rtlil/.gitignore
new file mode 100644
index 000000000..abe251a76
--- /dev/null
+++ b/tests/rtlil/.gitignore
@@ -0,0 +1 @@
+/temp
\ No newline at end of file
diff --git a/tests/rtlil/everything.v b/tests/rtlil/everything.v
new file mode 100644
index 000000000..666d630c2
--- /dev/null
+++ b/tests/rtlil/everything.v
@@ -0,0 +1,40 @@
+module alu(
+	input clk,
+	input [7:0] A,
+	input [7:0] B,
+	input [3:0] operation,
+	output reg [7:0] result,
+	output reg CF,
+	output reg ZF,
+	output reg SF
+);
+
+	localparam ALU_OP_ADD = 4'b0000;
+	localparam ALU_OP_SUB = 4'b0001;
+
+	reg [8:0] tmp;
+
+	always @(posedge clk)
+	begin
+		case (operation)
+			ALU_OP_ADD :
+				tmp = A + B;
+			ALU_OP_SUB :
+				tmp = A - B;
+		endcase
+
+		CF <= tmp[8];
+		ZF <= tmp[7:0] == 0;
+		SF <= tmp[7];
+
+		result <= tmp[7:0];
+	end
+endmodule
+
+module foo(
+    input [7:0] a, input [7:0] b, output [7:0] y
+);
+    wire [7:0] bb;
+    assign b = bb;
+    assign y = a + bb;
+endmodule
diff --git a/tests/rtlil/roundtrip-design.sh b/tests/rtlil/roundtrip-design.sh
new file mode 100644
index 000000000..018e363c7
--- /dev/null
+++ b/tests/rtlil/roundtrip-design.sh
@@ -0,0 +1,10 @@
+set -euo pipefail
+YS=../../yosys
+
+mkdir -p temp
+
+$YS -p "read_verilog -sv everything.v; write_rtlil temp/roundtrip-design-push.il; design -push; design -pop; write_rtlil temp/roundtrip-design-pop.il"
+diff temp/roundtrip-design-push.il temp/roundtrip-design-pop.il
+
+$YS -p "read_verilog -sv everything.v; write_rtlil temp/roundtrip-design-save.il; design -save foo; design -load foo; write_rtlil temp/roundtrip-design-load.il"
+diff temp/roundtrip-design-save.il temp/roundtrip-design-load.il
diff --git a/tests/rtlil/roundtrip-text.sh b/tests/rtlil/roundtrip-text.sh
new file mode 100644
index 000000000..35417cff7
--- /dev/null
+++ b/tests/rtlil/roundtrip-text.sh
@@ -0,0 +1,31 @@
+set -euo pipefail
+YS=../../yosys
+
+mkdir -p temp
+
+# non-POSIX sed -i inconsistency workaround
+remove_empty_lines() {
+    local file="$1"
+    sed '/^$/d' "$file" > temp/tmp
+    mv temp/tmp "$file"
+}
+
+# write_rtlil and dump are equivalent
+$YS -p "read_verilog -sv everything.v; copy alu zzz; proc zzz; dump -o temp/roundtrip-text.dump.il; write_rtlil temp/roundtrip-text.write.il"
+remove_empty_lines temp/roundtrip-text.dump.il
+remove_empty_lines temp/roundtrip-text.write.il
+# Trim first line ("Generated by Yosys ...")
+tail -n +2 temp/roundtrip-text.write.il > temp/roundtrip-text.write-nogen.il
+diff temp/roundtrip-text.dump.il temp/roundtrip-text.write-nogen.il
+
+# Loading and writing it out again doesn't change the RTLIL
+$YS -p "read_rtlil temp/roundtrip-text.dump.il; write_rtlil temp/roundtrip-text.reload.il"
+remove_empty_lines temp/roundtrip-text.reload.il
+tail -n +2 temp/roundtrip-text.reload.il > temp/roundtrip-text.reload-nogen.il
+diff temp/roundtrip-text.dump.il temp/roundtrip-text.reload-nogen.il
+
+# Hashing differences don't change the RTLIL
+$YS --hash-seed=2345678 -p "read_rtlil temp/roundtrip-text.dump.il; write_rtlil temp/roundtrip-text.reload-hash.il"
+remove_empty_lines temp/roundtrip-text.reload-hash.il
+tail -n +2 temp/roundtrip-text.reload-hash.il > temp/roundtrip-text.reload-hash-nogen.il
+diff temp/roundtrip-text.dump.il temp/roundtrip-text.reload-hash-nogen.il
diff --git a/tests/rtlil/run-test.sh b/tests/rtlil/run-test.sh
new file mode 100755
index 000000000..70b282a9a
--- /dev/null
+++ b/tests/rtlil/run-test.sh
@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+set -eu
+source ../gen-tests-makefile.sh
+generate_mk --bash