diff --git a/.github/workflows/extra-builds.yml b/.github/workflows/extra-builds.yml
index b22a399db..e8b11ef2f 100644
--- a/.github/workflows/extra-builds.yml
+++ b/.github/workflows/extra-builds.yml
@@ -37,7 +37,7 @@ jobs:
           persist-credentials: false
       - run: sudo apt-get install libfl-dev
       - name: Build
-        run: make vcxsrc YOSYS_VER=latest
+        run: make vcxsrc YOSYS_COMPILER="Visual Studio" VCX_DIR_NAME=yosys-win32-vcxsrc-latest
       - uses: actions/upload-artifact@v4
         with:
           name: vcxsrc
diff --git a/Makefile b/Makefile
index 62eef4519..d4b17b2cb 100644
--- a/Makefile
+++ b/Makefile
@@ -177,7 +177,7 @@ ifeq ($(OS), Haiku)
 CXXFLAGS += -D_DEFAULT_SOURCE
 endif
 
-YOSYS_VER := 0.60+8
+YOSYS_VER := 0.60+51
 YOSYS_MAJOR := $(shell echo $(YOSYS_VER) | cut -d'.' -f1)
 YOSYS_MINOR := $(shell echo $(YOSYS_VER) | cut -d'.' -f2)
 YOSYS_COMMIT := $(shell echo $(YOSYS_VER) | cut -d'.' -f3)
@@ -193,8 +193,10 @@ CXXFLAGS += -DYOSYS_VER=\\"$(YOSYS_VER)\\" \
 TARBALL_GIT_REV := $(shell cat $(YOSYS_SRC)/.gitcommit)
 ifneq ($(findstring Format:,$(TARBALL_GIT_REV)),)
 GIT_REV := $(shell cd .. && git rev-parse --short=9 HEAD || echo UNKNOWN)
+GIT_DIRTY := $(shell cd .. && git diff --exit-code --quiet 2>/dev/null; if [ $$? -ne 0 ]; then echo "-dirty"; fi)
 else
 GIT_REV := $(TARBALL_GIT_REV)
+GIT_DIRTY := ""
 endif
 
 OBJS = kernel/version_$(GIT_REV).o
@@ -845,12 +847,13 @@ endif
 	$(Q) mkdir -p $(dir $@)
 	$(P) $(CXX) -o $@ -c $(CPPFLAGS) $(CXXFLAGS) $<
 
-YOSYS_VER_STR := Preqorsor $(YOSYS_VER) (git sha1 $(GIT_REV), $(notdir $(CXX)) $(shell \
-		$(CXX) --version | tr ' ()' '\n' | grep '^[0-9]' | head -n1) $(filter -f% -m% -O% -DNDEBUG,$(CXXFLAGS)))
+YOSYS_GIT_STR := $(GIT_REV)$(GIT_DIRTY)
+YOSYS_COMPILER := $(notdir $(CXX)) $(shell $(CXX) --version | tr ' ()' '\n' | grep '^[0-9]' | head -n1) $(filter -f% -m% -O% -DNDEBUG,$(CXXFLAGS))
+YOSYS_VER_STR := Preqorsor $(YOSYS_VER) (git sha1 $(YOSYS_GIT_STR), $(YOSYS_COMPILER))
 
 kernel/version_$(GIT_REV).cc: $(YOSYS_SRC)/Makefile
 	$(P) rm -f kernel/version_*.o kernel/version_*.d kernel/version_*.cc
-	$(Q) mkdir -p kernel && echo "namespace Yosys { extern const char *yosys_version_str; const char *yosys_version_str=\"$(YOSYS_VER_STR)\"; }" > kernel/version_$(GIT_REV).cc
+	$(Q) mkdir -p kernel && echo "namespace Yosys { extern const char *yosys_version_str; const char *yosys_version_str=\"$(YOSYS_VER_STR)\"; const char *yosys_git_hash_str=\"$(YOSYS_GIT_STR)\"; }" > kernel/version_$(GIT_REV).cc
 
 ifeq ($(ENABLE_VERIFIC),1)
 CXXFLAGS_NOVERIFIC = $(foreach v,$(CXXFLAGS),$(if $(findstring $(VERIFIC_DIR),$(v)),,$(v)))
@@ -1104,7 +1107,9 @@ ifeq ($(ENABLE_PYOSYS),1)
 	$(INSTALL_SUDO) cp libyosys.so $(DESTDIR)$(PYTHON_DESTDIR)/$(subst -,_,$(PROGRAM_PREFIX))pyosys/libyosys.so
 	$(INSTALL_SUDO) cp -r share $(DESTDIR)$(PYTHON_DESTDIR)/$(subst -,_,$(PROGRAM_PREFIX))pyosys
 ifeq ($(ENABLE_ABC),1)
-	$(INSTALL_SUDO) cp yosys-abc $(DESTDIR)$(PYTHON_DESTDIR)/$(subst -,_,$(PROGRAM_PREFIX))pyosys/yosys-abc
+ifeq ($(ABCEXTERNAL),)
+	$(INSTALL_SUDO) cp $(PROGRAM_PREFIX)yosys-abc$(EXE) $(DESTDIR)$(PYTHON_DESTDIR)/$(subst -,_,$(PROGRAM_PREFIX))pyosys/yosys-abc$(EXE)
+endif
 endif
 endif
 endif
@@ -1255,15 +1260,17 @@ qtcreator:
 	{ echo .; find backends frontends kernel libs passes -type f \( -name '*.h' -o -name '*.hh' \) -printf '%h\n' | sort -u; } > qtcreator.includes
 	touch qtcreator.creator
 
-vcxsrc: $(GENFILES) $(EXTRA_TARGETS)
-	rm -rf yosys-win32-vcxsrc-$(YOSYS_VER){,.zip}
+VCX_DIR_NAME := yosys-win32-vcxsrc-$(YOSYS_VER)
+vcxsrc: $(GENFILES) $(EXTRA_TARGETS) kernel/version_$(GIT_REV).cc
+	rm -rf $(VCX_DIR_NAME){,.zip}
+	cp -f kernel/version_$(GIT_REV).cc kernel/version.cc
 	set -e; for f in `ls $(filter %.cc %.cpp,$(GENFILES)) $(addsuffix .cc,$(basename $(OBJS))) $(addsuffix .cpp,$(basename $(OBJS))) 2> /dev/null`; do \
 		echo "Analyse: $$f" >&2; cpp -std=c++17 -MM -I. -D_YOSYS_ $$f; done | sed 's,.*:,,; s,//*,/,g; s,/[^/]*/\.\./,/,g; y, \\,\n\n,;' | grep '^[^/]' | sort -u | grep -v kernel/version_ > srcfiles.txt
 	echo "libs/fst/fst_win_unistd.h" >> srcfiles.txt
-	bash misc/create_vcxsrc.sh yosys-win32-vcxsrc $(YOSYS_VER) $(GIT_REV)
-	echo "namespace Yosys { extern const char *yosys_version_str; const char *yosys_version_str=\"Yosys (Version Information Unavailable)\"; }" > kernel/version.cc
-	zip yosys-win32-vcxsrc-$(YOSYS_VER)/genfiles.zip $(GENFILES) kernel/version.cc
-	zip -r yosys-win32-vcxsrc-$(YOSYS_VER).zip yosys-win32-vcxsrc-$(YOSYS_VER)/
+	echo "kernel/version.cc" >> srcfiles.txt
+	bash misc/create_vcxsrc.sh $(VCX_DIR_NAME) $(YOSYS_VER)
+	zip $(VCX_DIR_NAME)/genfiles.zip $(GENFILES) kernel/version.cc
+	zip -r $(VCX_DIR_NAME).zip $(VCX_DIR_NAME)/
 	rm -f srcfiles.txt kernel/version.cc
 
 config-clean: clean
diff --git a/abc b/abc
index 177496d13..bd05a6454 160000
--- a/abc
+++ b/abc
@@ -1 +1 @@
-Subproject commit 177496d1399822a2910754fdc32f48ed8b1cd265
+Subproject commit bd05a6454e8c157caaa58ceda676ae0249d8e27c
diff --git a/kernel/cellaigs.cc b/kernel/cellaigs.cc
index fd3c7bb67..0f897cd58 100644
--- a/kernel/cellaigs.cc
+++ b/kernel/cellaigs.cc
@@ -185,50 +185,68 @@ struct AigMaker
 
 	int or_gate(int A, int B)
 	{
-		return nand_gate(not_gate(A), not_gate(B));
+		int not_a = not_gate(A);
+		int not_b = not_gate(B);
+		return nand_gate(not_a, not_b);
 	}
 
 	int nor_gate(int A, int B)
 	{
-		return and_gate(not_gate(A), not_gate(B));
+		int not_a = not_gate(A);
+		int not_b = not_gate(B);
+		return and_gate(not_a, not_b);
 	}
 
 	int xor_gate(int A, int B)
 	{
-		return nor_gate(and_gate(A, B), nor_gate(A, B));
+		int a_and_b = and_gate(A, B);
+		int a_nor_b = nor_gate(A, B);
+		return nor_gate(a_and_b, a_nor_b);
 	}
 
 	int xnor_gate(int A, int B)
 	{
-		return or_gate(and_gate(A, B), nor_gate(A, B));
+		int a_and_b = and_gate(A, B);
+		int a_nor_b = nor_gate(A, B);
+		return or_gate(a_and_b, a_nor_b);
 	}
 
 	int andnot_gate(int A, int B)
 	{
-		return and_gate(A, not_gate(B));
+		int not_b = not_gate(B);
+		return and_gate(A, not_b);
 	}
 
 	int ornot_gate(int A, int B)
 	{
-		return or_gate(A, not_gate(B));
+		int not_b = not_gate(B);
+		return or_gate(A, not_b);
 	}
 
 	int mux_gate(int A, int B, int S)
 	{
-		return or_gate(and_gate(A, not_gate(S)), and_gate(B, S));
+		int not_s = not_gate(S);
+		int a_active = and_gate(A, not_s);
+		int b_active = and_gate(B, S);
+		return or_gate(a_active, b_active);
 	}
 
-	vector<int> adder(const vector<int> &A, const vector<int> &B, int carry, vector<int> *X = nullptr, vector<int> *CO = nullptr)
+	vector<int> adder(const vector<int> &A, const vector<int> &B, int carry_in, vector<int> *X = nullptr, vector<int> *CO = nullptr)
 	{
 		vector<int> Y(GetSize(A));
 		log_assert(GetSize(A) == GetSize(B));
 		for (int i = 0; i < GetSize(A); i++) {
-			Y[i] = xor_gate(xor_gate(A[i], B[i]), carry);
-			carry = or_gate(and_gate(A[i], B[i]), and_gate(or_gate(A[i], B[i]), carry));
+			int a_xor_b = xor_gate(A[i], B[i]);
+			int a_or_b = or_gate(A[i], B[i]);
+			int a_and_b = and_gate(A[i], B[i]);
+			Y[i] = xor_gate(a_xor_b, carry_in);
+			int tmp = and_gate(a_or_b, carry_in);
+			int carry_out = or_gate(a_and_b, tmp);
 			if (X != nullptr)
-				X->at(i) = xor_gate(A[i], B[i]);
+				X->at(i) = a_xor_b;
 			if (CO != nullptr)
-				CO->at(i) = carry;
+				CO->at(i) = carry_out;
+			carry_in = carry_out;
 		}
 		return Y;
 	}
@@ -307,13 +325,13 @@ Aig::Aig(Cell *cell)
 			int A = mk.inport(ID::A, i);
 			int B = mk.inport(ID::B, i);
 			int Y = cell->type.in(ID($and), ID($_AND_))   ? mk.and_gate(A, B) :
-			        cell->type.in(ID($_NAND_))          ? mk.nand_gate(A, B) :
+			        cell->type.in(ID($_NAND_))            ? mk.nand_gate(A, B) :
 			        cell->type.in(ID($or), ID($_OR_))     ? mk.or_gate(A, B) :
-			        cell->type.in(ID($_NOR_))           ? mk.nor_gate(A, B) :
+			        cell->type.in(ID($_NOR_))             ? mk.nor_gate(A, B) :
 			        cell->type.in(ID($xor), ID($_XOR_))   ? mk.xor_gate(A, B) :
 			        cell->type.in(ID($xnor), ID($_XNOR_)) ? mk.xnor_gate(A, B) :
-			        cell->type.in(ID($_ANDNOT_))        ? mk.andnot_gate(A, B) :
-			        cell->type.in(ID($_ORNOT_))         ? mk.ornot_gate(A, B) : -1;
+			        cell->type.in(ID($_ANDNOT_))          ? mk.andnot_gate(A, B) :
+			        cell->type.in(ID($_ORNOT_))           ? mk.ornot_gate(A, B) : -1;
 			mk.outport(Y, ID::Y, i);
 		}
 		goto optimize;
@@ -465,7 +483,8 @@ Aig::Aig(Cell *cell)
 		int B = mk.inport(ID::B);
 		int C = mk.inport(ID::C);
 		int D = mk.inport(ID::D);
-		int Y = mk.nor_gate(mk.and_gate(A, B), mk.and_gate(C, D));
+		int a_and_b = mk.and_gate(A, B);
+		int Y = mk.nor_gate(a_and_b, mk.and_gate(C, D));
 		mk.outport(Y, ID::Y);
 		goto optimize;
 	}
@@ -476,7 +495,8 @@ Aig::Aig(Cell *cell)
 		int B = mk.inport(ID::B);
 		int C = mk.inport(ID::C);
 		int D = mk.inport(ID::D);
-		int Y = mk.nand_gate(mk.or_gate(A, B), mk.or_gate(C, D));
+		int a_or_b = mk.or_gate(A, B);
+		int Y = mk.nand_gate(a_or_b, mk.or_gate(C, D));
 		mk.outport(Y, ID::Y);
 		goto optimize;
 	}
diff --git a/kernel/driver.cc b/kernel/driver.cc
index 06fa6b11b..fa78bad59 100644
--- a/kernel/driver.cc
+++ b/kernel/driver.cc
@@ -255,6 +255,7 @@ int main(int argc, char **argv)
 		("h,help", "print this help message. If given, print help for <command>.",
 			cxxopts::value<std::string>(), "[<command>]")
 		("V,version", "print version information and exit")
+		("git-hash", "print git commit hash and exit")
 		("infile", "input files", cxxopts::value<std::vector<std::string>>())
 	;
 	options.add_options("logging")
@@ -332,6 +333,10 @@ int main(int argc, char **argv)
 			std::cout << yosys_version_str << std::endl;
 			exit(0);
 		}
+		if (result.count("git-hash")) {
+			std::cout << yosys_git_hash_str << std::endl;
+			exit(0);
+		}
 		if (result.count("S")) {
 			passes_commands.push_back("synth");
 			run_shell = false;
diff --git a/kernel/log.cc b/kernel/log.cc
index 5cd1d7f4f..2a1261621 100644
--- a/kernel/log.cc
+++ b/kernel/log.cc
@@ -203,6 +203,8 @@ static void logv_string(std::string_view format, std::string str) {
 
 void log_formatted_string(std::string_view format, std::string str)
 {
+	log_assert(!Multithreading::active());
+
 	if (log_make_debug && !ys_debug(1))
 		return;
 	logv_string(format, std::move(str));
@@ -210,6 +212,8 @@ void log_formatted_string(std::string_view format, std::string str)
 
 void log_formatted_header(RTLIL::Design *design, std::string_view format, std::string str)
 {
+	log_assert(!Multithreading::active());
+
 	bool pop_errfile = false;
 
 	log_spacer();
@@ -249,6 +253,8 @@ void log_formatted_header(RTLIL::Design *design, std::string_view format, std::s
 
 void log_formatted_warning(std::string_view prefix, std::string message)
 {
+	log_assert(!Multithreading::active());
+
 	bool suppressed = false;
 
 	for (auto &re : log_nowarn_regexes)
diff --git a/kernel/threading.cc b/kernel/threading.cc
index 49fddaa7c..dcc044c89 100644
--- a/kernel/threading.cc
+++ b/kernel/threading.cc
@@ -3,6 +3,20 @@
 
 YOSYS_NAMESPACE_BEGIN
 
+static int init_max_threads()
+{
+	const char *v = getenv("YOSYS_MAX_THREADS");
+	if (v == nullptr)
+		return INT32_MAX;
+	return atoi(v);
+}
+
+static int get_max_threads()
+{
+	static int max_threads = init_max_threads();
+	return max_threads;
+}
+
 void DeferredLogs::flush()
 {
 	for (auto &m : logs)
@@ -12,10 +26,11 @@ void DeferredLogs::flush()
 			YOSYS_NAMESPACE_PREFIX log("%s", m.text.c_str());
 }
 
-int ThreadPool::pool_size(int reserved_cores, int max_threads)
+int ThreadPool::pool_size(int reserved_cores, int max_worker_threads)
 {
 #ifdef YOSYS_ENABLE_THREADS
-	int num_threads = std::min<int>(std::thread::hardware_concurrency() - reserved_cores, max_threads);
+	int available_threads = std::min<int>(std::thread::hardware_concurrency(), get_max_threads());
+	int num_threads = std::min(available_threads - reserved_cores, max_worker_threads);
         return std::max(0, num_threads);
 #else
         return 0;
diff --git a/kernel/threading.h b/kernel/threading.h
index c34abf850..b8cd62f87 100644
--- a/kernel/threading.h
+++ b/kernel/threading.h
@@ -127,9 +127,9 @@ class ThreadPool
 public:
 	// Computes the number of worker threads to use.
 	// `reserved_cores` cores are set aside for other threads (e.g. work on the main thread).
-	// `max_threads` --- don't return more workers than this.
+	// `max_worker_threads` --- don't return more workers than this.
 	// The result may be 0.
-	static int pool_size(int reserved_cores, int max_threads);
+	static int pool_size(int reserved_cores, int max_worker_threads);
 
 	// Create a pool of threads running the given closure (parameterized by thread number).
 	// `pool_size` must be the result of a `pool_size()` call.
diff --git a/kernel/yosys.h b/kernel/yosys.h
index b455ad496..9f5a16a9c 100644
--- a/kernel/yosys.h
+++ b/kernel/yosys.h
@@ -81,6 +81,7 @@ extern std::set<std::string> yosys_input_files, yosys_output_files;
 
 // from kernel/version_*.o (cc source generated from Makefile)
 extern const char *yosys_version_str;
+extern const char *yosys_git_hash_str;
 const char* yosys_maybe_version();
 
 // from passes/cmds/design.cc
diff --git a/kernel/yosys_common.h b/kernel/yosys_common.h
index 7e023af23..79e913cb9 100644
--- a/kernel/yosys_common.h
+++ b/kernel/yosys_common.h
@@ -299,8 +299,8 @@ RTLIL::IdString new_id_suffix(std::string_view file, int line, std::string_view
 
 #define NEW_ID \
 	YOSYS_NAMESPACE_PREFIX RTLIL::IdString::new_autoidx_with_prefix([](std::string_view func) -> const std::string * { \
-		static const std::string *prefix = YOSYS_NAMESPACE_PREFIX create_id_prefix(__FILE__, __LINE__, func); \
-		return prefix; \
+		static std::unique_ptr<const std::string> prefix(YOSYS_NAMESPACE_PREFIX create_id_prefix(__FILE__, __LINE__, func)); \
+		return prefix.get(); \
 	}(__FUNCTION__))
 #define NEW_ID_SUFFIX(suffix) \
 	YOSYS_NAMESPACE_PREFIX new_id_suffix(__FILE__, __LINE__, __FUNCTION__, suffix)
diff --git a/misc/create_vcxsrc.sh b/misc/create_vcxsrc.sh
index 228003bad..42a690ce6 100644
--- a/misc/create_vcxsrc.sh
+++ b/misc/create_vcxsrc.sh
@@ -1,9 +1,8 @@
 #!/bin/bash
 
 set -ex
-vcxsrc="$1-$2"
+vcxsrc="$1"
 yosysver="$2"
-gitsha="$3"
 
 rm -rf YosysVS-Tpl-v2.zip YosysVS
 wget https://github.com/YosysHQ/yosys/releases/download/resources/YosysVS-Tpl-v2.zip
@@ -33,7 +32,6 @@ popd
 	head -n$n "$vcxsrc"/YosysVS/YosysVS.vcxproj
 	egrep '\.(h|hh|hpp|inc)$' srcfiles.txt | sed 's,.*,<ClInclude Include="../yosys/&" />,'
 	egrep -v '\.(h|hh|hpp|inc)$' srcfiles.txt | sed 's,.*,<ClCompile Include="../yosys/&" />,'
-	echo '<ClCompile Include="../yosys/kernel/version.cc" />'
 	tail -n +$((n+1)) "$vcxsrc"/YosysVS/YosysVS.vcxproj
 } > "$vcxsrc"/YosysVS/YosysVS.vcxproj.new
 
@@ -48,9 +46,6 @@ mkdir -p "$vcxsrc"/yosys
 tar -cf - -T srcfiles.txt | tar -xf - -C "$vcxsrc"/yosys
 cp -r share "$vcxsrc"/
 
-echo "namespace Yosys { extern const char *yosys_version_str; const char *yosys_version_str=\"Yosys" \
-		"$yosysver (git sha1 $gitsha, Visual Studio)\"; }" > "$vcxsrc"/yosys/kernel/version.cc
-
 cat > "$vcxsrc"/readme-git.txt << EOT
 Want to use a git working copy for the yosys source code?
 Open "Git Bash" in this directory and run:
diff --git a/passes/techmap/abc.cc b/passes/techmap/abc.cc
index aa311374c..6d8446f82 100644
--- a/passes/techmap/abc.cc
+++ b/passes/techmap/abc.cc
@@ -255,8 +255,8 @@ std::optional<AbcProcess> spawn_abc(const char* abc_exe, DeferredLogs &logs) {
 
 	char arg1[] = "-s";
 	char* argv[] = { strdup(abc_exe), arg1, nullptr };
-	if (0 != posix_spawn(&result.pid, abc_exe, &file_actions, nullptr, argv, environ)) {
-		logs.log_error("posix_spawn %s failed", abc_exe);
+	if (0 != posix_spawnp(&result.pid, abc_exe, &file_actions, nullptr, argv, environ)) {
+		logs.log_error("posix_spawnp %s failed", abc_exe);
 		return std::nullopt;
 	}
 	free(argv[0]);
diff --git a/passes/tests/test_cell.cc b/passes/tests/test_cell.cc
index 73af155bd..4d28e659b 100644
--- a/passes/tests/test_cell.cc
+++ b/passes/tests/test_cell.cc
@@ -1143,7 +1143,29 @@ struct TestCellPass : public Pass {
 				else
 					uut = create_gold_module(design, cell_type, cell_types.at(cell_type), constmode, muxdiv);
 				if (!write_prefix.empty()) {
-					Pass::call(design, stringf("write_rtlil %s_%s_%05d.il", write_prefix, cell_type.c_str()+1, i));
+					string writer = "write_rtlil";
+					string suffix = "il";
+					if (techmap_cmd.compare("aigmap") == 0) {
+						// try to convert to aiger
+						Pass::call(design, techmap_cmd);
+						bool is_unconverted = false;
+						for (auto *mod : design->selected_modules())
+							for (auto *cell : mod->selected_cells())
+								if (!cell->type.in(ID::$_NOT_, ID::$_AND_)) {
+									is_unconverted = true;
+									break;
+								}
+						if (is_unconverted) {
+							// skip unconverted cells
+							log_warning("Skipping %s\n", cell_type);
+							delete design;
+							break;
+						} else {
+							writer = "write_aiger -ascii";
+							suffix = "aag";
+						}
+					}
+					Pass::call(design, stringf("%s %s_%s_%05d.%s", writer, write_prefix, cell_type.c_str()+1, i, suffix));
 				} else if (edges) {
 					Pass::call(design, "dump gold");
 					run_edges_test(design, verbose);
diff --git a/techlibs/ice40/ice40_wrapcarry.cc b/techlibs/ice40/ice40_wrapcarry.cc
index b0588f5e1..41ab2fa6f 100644
--- a/techlibs/ice40/ice40_wrapcarry.cc
+++ b/techlibs/ice40/ice40_wrapcarry.cc
@@ -138,7 +138,7 @@ struct Ice40WrapCarryPass : public Pass {
 							lut->attributes[a.first.c_str() + strlen("\\SB_LUT4.")] = a.second;
 						else if (a.first == ID::src)
 							src = a.second;
-						else if (a.first.in(IdString{"\\SB_LUT4.name"}, ID::keep, ID::module_not_derived))
+						else if (a.first.in(IdString{"\\SB_LUT4.name"}, ID::keep, ID::module_not_derived, ID::src))
 							continue;
 						else
 							continue;
diff --git a/tests/aiger/.gitignore b/tests/aiger/.gitignore
index 4bb3e67f6..ef347c9d3 100644
--- a/tests/aiger/.gitignore
+++ b/tests/aiger/.gitignore
@@ -1,2 +1,3 @@
 /*_ref.v
 /neg.out/
+/gate/
diff --git a/tests/aiger/gold/__ANDNOT__00000.aag b/tests/aiger/gold/__ANDNOT__00000.aag
new file mode 100644
index 000000000..93f5c0044
--- /dev/null
+++ b/tests/aiger/gold/__ANDNOT__00000.aag
@@ -0,0 +1,7 @@
+aag 3 2 0 1 1
+2
+4
+6
+6 5 2
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__AND__00000.aag b/tests/aiger/gold/__AND__00000.aag
new file mode 100644
index 000000000..5b0148022
--- /dev/null
+++ b/tests/aiger/gold/__AND__00000.aag
@@ -0,0 +1,7 @@
+aag 3 2 0 1 1
+2
+4
+6
+6 4 2
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__AOI3__00000.aag b/tests/aiger/gold/__AOI3__00000.aag
new file mode 100644
index 000000000..a726927fe
--- /dev/null
+++ b/tests/aiger/gold/__AOI3__00000.aag
@@ -0,0 +1,9 @@
+aag 5 3 0 1 2
+2
+4
+6
+10
+8 4 2
+10 9 7
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__AOI4__00000.aag b/tests/aiger/gold/__AOI4__00000.aag
new file mode 100644
index 000000000..4044dc5a8
--- /dev/null
+++ b/tests/aiger/gold/__AOI4__00000.aag
@@ -0,0 +1,11 @@
+aag 7 4 0 1 3
+2
+4
+6
+8
+14
+10 4 2
+12 8 6
+14 13 11
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__BUF__00000.aag b/tests/aiger/gold/__BUF__00000.aag
new file mode 100644
index 000000000..7a4cd3156
--- /dev/null
+++ b/tests/aiger/gold/__BUF__00000.aag
@@ -0,0 +1,5 @@
+aag 1 1 0 1 0
+2
+2
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__MUX__00000.aag b/tests/aiger/gold/__MUX__00000.aag
new file mode 100644
index 000000000..4d1757a65
--- /dev/null
+++ b/tests/aiger/gold/__MUX__00000.aag
@@ -0,0 +1,10 @@
+aag 6 3 0 1 3
+2
+4
+6
+13
+8 7 2
+10 6 4
+12 11 9
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__NAND__00000.aag b/tests/aiger/gold/__NAND__00000.aag
new file mode 100644
index 000000000..bc42187b1
--- /dev/null
+++ b/tests/aiger/gold/__NAND__00000.aag
@@ -0,0 +1,7 @@
+aag 3 2 0 1 1
+2
+4
+7
+6 4 2
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__NMUX__00000.aag b/tests/aiger/gold/__NMUX__00000.aag
new file mode 100644
index 000000000..b939855f9
--- /dev/null
+++ b/tests/aiger/gold/__NMUX__00000.aag
@@ -0,0 +1,10 @@
+aag 6 3 0 1 3
+2
+4
+6
+12
+8 7 2
+10 6 4
+12 11 9
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__NOR__00000.aag b/tests/aiger/gold/__NOR__00000.aag
new file mode 100644
index 000000000..30b1d6c95
--- /dev/null
+++ b/tests/aiger/gold/__NOR__00000.aag
@@ -0,0 +1,7 @@
+aag 3 2 0 1 1
+2
+4
+6
+6 5 3
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__NOT__00000.aag b/tests/aiger/gold/__NOT__00000.aag
new file mode 100644
index 000000000..0c9119cea
--- /dev/null
+++ b/tests/aiger/gold/__NOT__00000.aag
@@ -0,0 +1,5 @@
+aag 1 1 0 1 0
+2
+3
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__OAI3__00000.aag b/tests/aiger/gold/__OAI3__00000.aag
new file mode 100644
index 000000000..9f8af1f72
--- /dev/null
+++ b/tests/aiger/gold/__OAI3__00000.aag
@@ -0,0 +1,9 @@
+aag 5 3 0 1 2
+2
+4
+6
+11
+8 5 3
+10 9 6
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__OAI4__00000.aag b/tests/aiger/gold/__OAI4__00000.aag
new file mode 100644
index 000000000..871c05ba3
--- /dev/null
+++ b/tests/aiger/gold/__OAI4__00000.aag
@@ -0,0 +1,11 @@
+aag 7 4 0 1 3
+2
+4
+6
+8
+15
+10 5 3
+12 9 7
+14 13 11
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__ORNOT__00000.aag b/tests/aiger/gold/__ORNOT__00000.aag
new file mode 100644
index 000000000..fc7263fce
--- /dev/null
+++ b/tests/aiger/gold/__ORNOT__00000.aag
@@ -0,0 +1,7 @@
+aag 3 2 0 1 1
+2
+4
+7
+6 4 3
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__OR__00000.aag b/tests/aiger/gold/__OR__00000.aag
new file mode 100644
index 000000000..d5e8085c2
--- /dev/null
+++ b/tests/aiger/gold/__OR__00000.aag
@@ -0,0 +1,7 @@
+aag 3 2 0 1 1
+2
+4
+7
+6 5 3
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__XNOR__00000.aag b/tests/aiger/gold/__XNOR__00000.aag
new file mode 100644
index 000000000..18bb92393
--- /dev/null
+++ b/tests/aiger/gold/__XNOR__00000.aag
@@ -0,0 +1,9 @@
+aag 5 2 0 1 3
+2
+4
+11
+6 4 2
+8 5 3
+10 9 7
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/__XOR__00000.aag b/tests/aiger/gold/__XOR__00000.aag
new file mode 100644
index 000000000..ab4bc32ad
--- /dev/null
+++ b/tests/aiger/gold/__XOR__00000.aag
@@ -0,0 +1,9 @@
+aag 5 2 0 1 3
+2
+4
+10
+6 4 2
+8 5 3
+10 9 7
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_add_00000.aag b/tests/aiger/gold/_add_00000.aag
new file mode 100644
index 000000000..9f22bc0f3
--- /dev/null
+++ b/tests/aiger/gold/_add_00000.aag
@@ -0,0 +1,62 @@
+aag 51 4 0 8 47
+2
+4
+6
+8
+14
+30
+42
+54
+66
+78
+90
+102
+10 6 2
+12 7 3
+14 13 11
+16 6 2
+18 8 4
+20 9 5
+22 21 19
+24 22 16
+26 21 19
+28 27 11
+30 29 25
+32 21 16
+34 33 19
+36 35 22
+38 33 19
+40 38 27
+42 41 37
+44 35 21
+46 45 19
+48 47 22
+50 45 19
+52 50 27
+54 53 49
+56 47 21
+58 57 19
+60 59 22
+62 57 19
+64 62 27
+66 65 61
+68 59 21
+70 69 19
+72 71 22
+74 69 19
+76 74 27
+78 77 73
+80 71 21
+82 81 19
+84 83 22
+86 81 19
+88 86 27
+90 89 85
+92 83 21
+94 93 19
+96 95 22
+98 93 19
+100 98 27
+102 101 97
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_alu_00000.aag b/tests/aiger/gold/_alu_00000.aag
new file mode 100644
index 000000000..3fdb09ea5
--- /dev/null
+++ b/tests/aiger/gold/_alu_00000.aag
@@ -0,0 +1,45 @@
+aag 33 5 0 9 28
+2
+4
+6
+8
+10
+27
+35
+36
+38
+40
+8
+48
+58
+66
+12 8 6
+14 9 7
+16 15 13
+18 16 2
+20 15 13
+22 21 3
+24 23 10
+26 25 19
+28 8 4
+30 9 5
+32 31 27
+34 33 29
+36 35 8
+38 23 19
+40 31 29
+42 38 10
+44 23 19
+46 45 11
+48 47 43
+50 40 27
+52 31 29
+54 25 19
+56 54 53
+58 57 51
+60 35 8
+62 33 29
+64 62 9
+66 65 61
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_and_00000.aag b/tests/aiger/gold/_and_00000.aag
new file mode 100644
index 000000000..6d3bab8d3
--- /dev/null
+++ b/tests/aiger/gold/_and_00000.aag
@@ -0,0 +1,28 @@
+aag 17 11 0 8 6
+2
+4
+6
+8
+10
+12
+14
+16
+18
+20
+22
+24
+26
+28
+30
+32
+34
+34
+34
+24 14 2
+26 16 4
+28 18 6
+30 20 8
+32 22 10
+34 22 12
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_buf_00000.aag b/tests/aiger/gold/_buf_00000.aag
new file mode 100644
index 000000000..d373a6a80
--- /dev/null
+++ b/tests/aiger/gold/_buf_00000.aag
@@ -0,0 +1,15 @@
+aag 6 6 0 6 0
+2
+4
+6
+8
+10
+12
+2
+4
+6
+8
+10
+12
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_eq_00000.aag b/tests/aiger/gold/_eq_00000.aag
new file mode 100644
index 000000000..e3cbcd2fc
--- /dev/null
+++ b/tests/aiger/gold/_eq_00000.aag
@@ -0,0 +1,46 @@
+aag 38 11 0 5 27
+2
+4
+6
+8
+10
+12
+14
+16
+18
+20
+22
+76
+0
+0
+0
+0
+24 10 2
+26 11 3
+28 27 25
+30 12 4
+32 13 5
+34 33 31
+36 35 29
+38 14 6
+40 15 7
+42 41 39
+44 43 36
+46 16 8
+48 17 9
+50 49 47
+52 51 44
+54 18 8
+56 19 9
+58 57 55
+60 59 52
+62 20 8
+64 21 9
+66 65 63
+68 67 60
+70 22 8
+72 23 9
+74 73 71
+76 75 68
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_ge_00000.aag b/tests/aiger/gold/_ge_00000.aag
new file mode 100644
index 000000000..8ccc44797
--- /dev/null
+++ b/tests/aiger/gold/_ge_00000.aag
@@ -0,0 +1,9 @@
+aag 3 2 0 3 1
+2
+4
+7
+0
+0
+6 4 3
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_gt_00000.aag b/tests/aiger/gold/_gt_00000.aag
new file mode 100644
index 000000000..cc0905ea1
--- /dev/null
+++ b/tests/aiger/gold/_gt_00000.aag
@@ -0,0 +1,48 @@
+aag 43 10 0 2 33
+2
+4
+6
+8
+10
+12
+14
+16
+18
+20
+86
+0
+22 20 7
+24 21 6
+26 25 23
+28 18 7
+30 16 7
+32 14 7
+34 12 7
+36 10 5
+38 9 2
+40 8 3
+42 41 38
+44 11 4
+46 45 43
+48 47 37
+50 13 6
+52 51 49
+54 53 35
+56 15 6
+58 57 55
+60 59 33
+62 17 6
+64 63 61
+66 65 31
+68 19 6
+70 69 67
+72 71 29
+74 73 25
+76 75 23
+78 77 26
+80 25 23
+82 75 23
+84 82 81
+86 85 79
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_le_00000.aag b/tests/aiger/gold/_le_00000.aag
new file mode 100644
index 000000000..75a138267
--- /dev/null
+++ b/tests/aiger/gold/_le_00000.aag
@@ -0,0 +1,52 @@
+aag 47 12 0 2 35
+2
+4
+6
+8
+10
+12
+14
+16
+18
+20
+22
+24
+94
+0
+26 25 8
+28 24 9
+30 29 27
+32 23 8
+34 21 8
+36 19 8
+38 17 8
+40 15 6
+42 13 4
+44 11 2
+46 12 5
+48 47 44
+50 49 43
+52 14 7
+54 53 51
+56 55 41
+58 16 9
+60 59 57
+62 61 39
+64 18 9
+66 65 63
+68 67 37
+70 20 9
+72 71 69
+74 73 35
+76 22 9
+78 77 75
+80 79 33
+82 81 29
+84 83 27
+86 85 30
+88 29 27
+90 83 27
+92 90 89
+94 93 87
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_logic_and_00000.aag b/tests/aiger/gold/_logic_and_00000.aag
new file mode 100644
index 000000000..d68c6fc34
--- /dev/null
+++ b/tests/aiger/gold/_logic_and_00000.aag
@@ -0,0 +1,30 @@
+aag 21 11 0 6 10
+2
+4
+6
+8
+10
+12
+14
+16
+18
+20
+22
+42
+0
+0
+0
+0
+0
+24 5 3
+26 24 7
+28 26 9
+30 28 11
+32 30 13
+34 17 15
+36 34 19
+38 36 21
+40 38 23
+42 41 33
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_logic_not_00000.aag b/tests/aiger/gold/_logic_not_00000.aag
new file mode 100644
index 000000000..7798b23e9
--- /dev/null
+++ b/tests/aiger/gold/_logic_not_00000.aag
@@ -0,0 +1,15 @@
+aag 7 4 0 5 3
+2
+4
+6
+8
+14
+0
+0
+0
+0
+10 5 3
+12 10 7
+14 12 9
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_logic_or_00000.aag b/tests/aiger/gold/_logic_or_00000.aag
new file mode 100644
index 000000000..12b3364d4
--- /dev/null
+++ b/tests/aiger/gold/_logic_or_00000.aag
@@ -0,0 +1,29 @@
+aag 21 11 0 5 10
+2
+4
+6
+8
+10
+12
+14
+16
+18
+20
+22
+43
+0
+0
+0
+0
+24 5 3
+26 24 7
+28 26 9
+30 28 11
+32 30 13
+34 17 15
+36 34 19
+38 36 21
+40 38 23
+42 40 32
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_lt_00000.aag b/tests/aiger/gold/_lt_00000.aag
new file mode 100644
index 000000000..2169b4a53
--- /dev/null
+++ b/tests/aiger/gold/_lt_00000.aag
@@ -0,0 +1,43 @@
+aag 34 9 0 6 25
+2
+4
+6
+8
+10
+12
+14
+16
+18
+68
+0
+0
+0
+0
+0
+20 19 10
+22 18 11
+24 23 21
+26 19 8
+28 17 6
+30 15 4
+32 12 3
+34 13 2
+36 35 32
+38 14 5
+40 39 37
+42 41 31
+44 16 7
+46 45 43
+48 47 29
+50 18 9
+52 51 49
+54 53 27
+56 55 23
+58 57 21
+60 59 24
+62 23 21
+64 57 21
+66 64 63
+68 67 61
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_mux_00000.aag b/tests/aiger/gold/_mux_00000.aag
new file mode 100644
index 000000000..4d1757a65
--- /dev/null
+++ b/tests/aiger/gold/_mux_00000.aag
@@ -0,0 +1,10 @@
+aag 6 3 0 1 3
+2
+4
+6
+13
+8 7 2
+10 6 4
+12 11 9
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_ne_00000.aag b/tests/aiger/gold/_ne_00000.aag
new file mode 100644
index 000000000..e4d894bde
--- /dev/null
+++ b/tests/aiger/gold/_ne_00000.aag
@@ -0,0 +1,40 @@
+aag 29 10 0 8 19
+2
+4
+6
+8
+10
+12
+14
+16
+18
+20
+59
+0
+0
+0
+0
+0
+0
+0
+22 12 2
+24 13 3
+26 25 23
+28 14 4
+30 15 5
+32 31 29
+34 33 27
+36 16 6
+38 17 7
+40 39 37
+42 41 34
+44 18 8
+46 19 9
+48 47 45
+50 49 42
+52 20 10
+54 21 11
+56 55 53
+58 57 50
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_not_00000.aag b/tests/aiger/gold/_not_00000.aag
new file mode 100644
index 000000000..3c5ede656
--- /dev/null
+++ b/tests/aiger/gold/_not_00000.aag
@@ -0,0 +1,11 @@
+aag 6 6 0 2 0
+2
+4
+6
+8
+10
+12
+3
+5
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_or_00000.aag b/tests/aiger/gold/_or_00000.aag
new file mode 100644
index 000000000..58714e461
--- /dev/null
+++ b/tests/aiger/gold/_or_00000.aag
@@ -0,0 +1,11 @@
+aag 6 4 0 2 2
+2
+4
+6
+8
+11
+13
+10 5 3
+12 7 3
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_pos_00000.aag b/tests/aiger/gold/_pos_00000.aag
new file mode 100644
index 000000000..29a2dd61a
--- /dev/null
+++ b/tests/aiger/gold/_pos_00000.aag
@@ -0,0 +1,9 @@
+aag 1 1 0 5 0
+2
+2
+2
+2
+2
+2
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_reduce_and_00000.aag b/tests/aiger/gold/_reduce_and_00000.aag
new file mode 100644
index 000000000..06db9a1dd
--- /dev/null
+++ b/tests/aiger/gold/_reduce_and_00000.aag
@@ -0,0 +1,7 @@
+aag 1 1 0 3 0
+2
+2
+0
+0
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_reduce_bool_00000.aag b/tests/aiger/gold/_reduce_bool_00000.aag
new file mode 100644
index 000000000..48a1410c8
--- /dev/null
+++ b/tests/aiger/gold/_reduce_bool_00000.aag
@@ -0,0 +1,13 @@
+aag 7 4 0 3 3
+2
+4
+6
+8
+15
+0
+0
+10 5 3
+12 10 7
+14 12 9
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_reduce_or_00000.aag b/tests/aiger/gold/_reduce_or_00000.aag
new file mode 100644
index 000000000..d5e8085c2
--- /dev/null
+++ b/tests/aiger/gold/_reduce_or_00000.aag
@@ -0,0 +1,7 @@
+aag 3 2 0 1 1
+2
+4
+7
+6 5 3
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_reduce_xnor_00000.aag b/tests/aiger/gold/_reduce_xnor_00000.aag
new file mode 100644
index 000000000..6ad6ac39e
--- /dev/null
+++ b/tests/aiger/gold/_reduce_xnor_00000.aag
@@ -0,0 +1,30 @@
+aag 25 6 0 2 19
+2
+4
+6
+8
+10
+12
+51
+0
+14 4 2
+16 5 3
+18 17 15
+20 18 6
+22 17 15
+24 23 7
+26 25 21
+28 26 8
+30 25 21
+32 31 9
+34 33 29
+36 34 10
+38 33 29
+40 39 11
+42 41 37
+44 42 12
+46 41 37
+48 47 13
+50 49 45
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_reduce_xor_00000.aag b/tests/aiger/gold/_reduce_xor_00000.aag
new file mode 100644
index 000000000..ab4bc32ad
--- /dev/null
+++ b/tests/aiger/gold/_reduce_xor_00000.aag
@@ -0,0 +1,9 @@
+aag 5 2 0 1 3
+2
+4
+10
+6 4 2
+8 5 3
+10 9 7
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_sub_00000.aag b/tests/aiger/gold/_sub_00000.aag
new file mode 100644
index 000000000..e9d976b32
--- /dev/null
+++ b/tests/aiger/gold/_sub_00000.aag
@@ -0,0 +1,20 @@
+aag 16 13 0 1 3
+2
+4
+6
+8
+10
+12
+14
+16
+18
+20
+22
+24
+26
+33
+28 17 2
+30 16 3
+32 31 29
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_xnor_00000.aag b/tests/aiger/gold/_xnor_00000.aag
new file mode 100644
index 000000000..9dd097862
--- /dev/null
+++ b/tests/aiger/gold/_xnor_00000.aag
@@ -0,0 +1,17 @@
+aag 10 4 0 4 6
+2
+4
+6
+8
+15
+21
+21
+21
+10 6 2
+12 7 3
+14 13 11
+16 8 4
+18 9 5
+20 19 17
+c
+Generated by Yosys
diff --git a/tests/aiger/gold/_xor_00000.aag b/tests/aiger/gold/_xor_00000.aag
new file mode 100644
index 000000000..453b8d0ee
--- /dev/null
+++ b/tests/aiger/gold/_xor_00000.aag
@@ -0,0 +1,12 @@
+aag 8 5 0 1 3
+2
+4
+6
+8
+10
+16
+12 8 2
+14 9 3
+16 15 13
+c
+Generated by Yosys
diff --git a/tests/aiger/run-test.sh b/tests/aiger/run-test.sh
index ca7339ff0..94d83ede4 100755
--- a/tests/aiger/run-test.sh
+++ b/tests/aiger/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 set -e
 
@@ -57,3 +58,13 @@ for y in *.ys; do
     echo "Running $y."
     ../../yosys -ql ${y%.*}.log $y
 done
+
+# compare aigmap with reference
+# make gold with: rm gold/*; yosys --no-version -p "test_cell -aigmap -w gold/ -n 1 -s 1 all"
+rm -rf gate; mkdir gate
+../../yosys --no-version -p "test_cell -aigmap -w gate/ -n 1 -s 1 all"
+(
+    set -o pipefail
+    diff --brief gold gate | tee aigmap.err
+)
+rm aigmap.err
diff --git a/tests/alumacc/run-test.sh b/tests/alumacc/run-test.sh
index e9698386e..2e3f5235c 100644
--- a/tests/alumacc/run-test.sh
+++ b/tests/alumacc/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 set -e
 for x in *.ys; do
   echo "Running $x.."
diff --git a/tests/arch/run-test.sh b/tests/arch/run-test.sh
index 68f925b34..7602717d2 100755
--- a/tests/arch/run-test.sh
+++ b/tests/arch/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 set -e
 
diff --git a/tests/asicworld/run-test.sh b/tests/asicworld/run-test.sh
index 5131ed646..c9b4118a7 100755
--- a/tests/asicworld/run-test.sh
+++ b/tests/asicworld/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 OPTIND=1
 seed=""    # default to no seed specified
diff --git a/tests/blif/run-test.sh b/tests/blif/run-test.sh
index e9698386e..2e3f5235c 100755
--- a/tests/blif/run-test.sh
+++ b/tests/blif/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 set -e
 for x in *.ys; do
   echo "Running $x.."
diff --git a/tests/bram/run-test.sh b/tests/bram/run-test.sh
index 37fc91d0e..47f24f5dd 100755
--- a/tests/bram/run-test.sh
+++ b/tests/bram/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 # run this test many times:
 # MAKE="make -j8" time bash -c 'for ((i=0; i<100; i++)); do echo "-- $i --"; bash run-test.sh || exit 1; done'
diff --git a/tests/common-env.sh b/tests/common-env.sh
new file mode 100644
index 000000000..f3a411280
--- /dev/null
+++ b/tests/common-env.sh
@@ -0,0 +1 @@
+export YOSYS_MAX_THREADS=4
diff --git a/tests/cxxrtl/run-test.sh b/tests/cxxrtl/run-test.sh
index 4b542e180..aa7a0c26c 100755
--- a/tests/cxxrtl/run-test.sh
+++ b/tests/cxxrtl/run-test.sh
@@ -1,4 +1,5 @@
 #!/bin/bash
+source ../common-env.sh
 
 set -ex
 
diff --git a/tests/fmt/run-test.sh b/tests/fmt/run-test.sh
index 88ee6e238..a3402f953 100644
--- a/tests/fmt/run-test.sh
+++ b/tests/fmt/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 set -ex
 
diff --git a/tests/fsm/run-test.sh b/tests/fsm/run-test.sh
index dc60c69c4..139ea8261 100755
--- a/tests/fsm/run-test.sh
+++ b/tests/fsm/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 # run this test many times:
 # time bash -c 'for ((i=0; i<100; i++)); do echo "-- $i --"; bash run-test.sh || exit 1; done'
diff --git a/tests/functional/run-test.sh b/tests/functional/run-test.sh
index e0bedf8d4..7c38f3190 100755
--- a/tests/functional/run-test.sh
+++ b/tests/functional/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
 
diff --git a/tests/gen-tests-makefile.sh b/tests/gen-tests-makefile.sh
index e3308506b..a0fb23ac3 100755
--- a/tests/gen-tests-makefile.sh
+++ b/tests/gen-tests-makefile.sh
@@ -9,7 +9,7 @@ generate_target() {
 	echo "all: $target_name"
 	echo ".PHONY: $target_name"
 	echo "$target_name:"
-	printf "\t@%s\n" "$test_command"
+	printf "\t@YOSYS_MAX_THREADS=4 %s\n" "$test_command"
 	printf "\t@echo 'Passed %s'\n" "$target_name"
 }
 
diff --git a/tests/hana/run-test.sh b/tests/hana/run-test.sh
index 99be37f5e..8533e5544 100755
--- a/tests/hana/run-test.sh
+++ b/tests/hana/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 OPTIND=1
 seed=""    # default to no seed specified
diff --git a/tests/liberty/run-test.sh b/tests/liberty/run-test.sh
index 5afdb727e..d5fb65e16 100755
--- a/tests/liberty/run-test.sh
+++ b/tests/liberty/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 set -eo pipefail
 
 for x in *.lib; do
diff --git a/tests/memfile/run-test.sh b/tests/memfile/run-test.sh
index db0ec54ee..44c1e4821 100755
--- a/tests/memfile/run-test.sh
+++ b/tests/memfile/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 set -e
 
diff --git a/tests/memlib/run-test.sh b/tests/memlib/run-test.sh
index 5f230a03e..9e95fb255 100755
--- a/tests/memlib/run-test.sh
+++ b/tests/memlib/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 set -eu
 
 OPTIND=1
diff --git a/tests/memories/run-test.sh b/tests/memories/run-test.sh
index 4f1da7ce7..8f83e11a1 100755
--- a/tests/memories/run-test.sh
+++ b/tests/memories/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 set -e
 
diff --git a/tests/opt_share/run-test.sh b/tests/opt_share/run-test.sh
index e80cd4214..e3a6e8b7b 100755
--- a/tests/opt_share/run-test.sh
+++ b/tests/opt_share/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 # run this test many times:
 # time bash -c 'for ((i=0; i<100; i++)); do echo "-- $i --"; bash run-test.sh || exit 1; done'
diff --git a/tests/peepopt/run-test.sh b/tests/peepopt/run-test.sh
index e9698386e..2e3f5235c 100644
--- a/tests/peepopt/run-test.sh
+++ b/tests/peepopt/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 set -e
 for x in *.ys; do
   echo "Running $x.."
diff --git a/tests/proc/run-test.sh b/tests/proc/run-test.sh
index e9698386e..2e3f5235c 100755
--- a/tests/proc/run-test.sh
+++ b/tests/proc/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 set -e
 for x in *.ys; do
   echo "Running $x.."
diff --git a/tests/rpc/run-test.sh b/tests/rpc/run-test.sh
index 624043750..0d58b0de2 100755
--- a/tests/rpc/run-test.sh
+++ b/tests/rpc/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 set -e
 for x in *.ys; do
   echo "Running $x.."
diff --git a/tests/select/run-test.sh b/tests/select/run-test.sh
index e9698386e..2e3f5235c 100755
--- a/tests/select/run-test.sh
+++ b/tests/select/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 set -e
 for x in *.ys; do
   echo "Running $x.."
diff --git a/tests/share/run-test.sh b/tests/share/run-test.sh
index a7b5fc4a0..0cef580a7 100755
--- a/tests/share/run-test.sh
+++ b/tests/share/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 # run this test many times:
 # time bash -c 'for ((i=0; i<100; i++)); do echo "-- $i --"; bash run-test.sh || exit 1; done'
diff --git a/tests/simple/run-test.sh b/tests/simple/run-test.sh
index b9e79f34a..c3711fe3e 100755
--- a/tests/simple/run-test.sh
+++ b/tests/simple/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 OPTIND=1
 seed=""    # default to no seed specified
diff --git a/tests/simple_abc9/run-test.sh b/tests/simple_abc9/run-test.sh
index 5669321ac..0b3e5061f 100755
--- a/tests/simple_abc9/run-test.sh
+++ b/tests/simple_abc9/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 
 OPTIND=1
 seed=""    # default to no seed specified
diff --git a/tests/svinterfaces/run-test.sh b/tests/svinterfaces/run-test.sh
index 71bdcd67a..28ce627d9 100755
--- a/tests/svinterfaces/run-test.sh
+++ b/tests/svinterfaces/run-test.sh
@@ -1,4 +1,5 @@
 #/bin/bash -e
+source ../common-env.sh
 
 ./runone.sh  svinterface1
 ./runone.sh  svinterface_at_top
diff --git a/tests/tools/autotest.sh b/tests/tools/autotest.sh
index 47b06d575..c9a12b66b 100755
--- a/tests/tools/autotest.sh
+++ b/tests/tools/autotest.sh
@@ -162,20 +162,24 @@ do
 			cp ../${bn}_tb.v ${bn}_tb.v
 		fi
 		if $genvcd; then sed -i 's,// \$dump,$dump,g' ${bn}_tb.v; fi
+		touch ${bn}.iverilog
 		compile_and_run ${bn}_tb_ref ${bn}_out_ref ${bn}_tb.v ${bn}_ref.${refext} "${libs[@]}" \
 					"$toolsdir"/../../techlibs/common/simlib.v \
 					"$toolsdir"/../../techlibs/common/simcells.v
+		rm ${bn}.iverilog
 		if $genvcd; then mv testbench.vcd ${bn}_ref.vcd; fi
 
 		test_count=0
 		test_passes() {
 			"$toolsdir"/../../yosys -b "verilog $backend_opts" -o ${bn}_syn${test_count}.v "$@"
+			touch ${bn}.iverilog
 			compile_and_run ${bn}_tb_syn${test_count} ${bn}_out_syn${test_count} \
 					${bn}_tb.v ${bn}_syn${test_count}.v "${libs[@]}" \
 					"$toolsdir"/../../techlibs/common/simlib.v \
 					"$toolsdir"/../../techlibs/common/simcells.v
 			if $genvcd; then mv testbench.vcd ${bn}_syn${test_count}.vcd; fi
 			"$toolsdir/cmp_tbdata" ${bn}_out_ref ${bn}_out_syn${test_count}
+			rm ${bn}.iverilog
 			test_count=$(( test_count + 1 ))
 		}
 
@@ -227,7 +231,9 @@ do
 	else
 		echo "${status_prefix}${did_firrtl}-> ERROR!"
 		if $warn_iverilog_git; then
-			echo "Note: Make sure that 'iverilog' is an up-to-date git checkout of Icarus Verilog."
+			if [ -f ${bn}.out/${bn}.iverilog ]; then
+				echo "Note: Make sure that 'iverilog' is an up-to-date git checkout of Icarus Verilog."
+			fi
 		fi
 		$keeprunning || exit 1
 	fi
diff --git a/tests/verific/run-test.sh b/tests/verific/run-test.sh
index 1d39e2093..1666ee1f9 100755
--- a/tests/verific/run-test.sh
+++ b/tests/verific/run-test.sh
@@ -2,4 +2,4 @@
 set -eu
 source ../gen-tests-makefile.sh
 generate_mk --yosys-scripts --bash
-echo "$(echo 'export ASAN_OPTIONS=halt_on_error=0'; cat run-test.mk)" > run-test.mk
\ No newline at end of file
+{ echo 'export ASAN_OPTIONS=halt_on_error=0'; cat run-test.mk; } > run-test.mk.tmp && mv run-test.mk.tmp run-test.mk
diff --git a/tests/xprop/run-test.sh b/tests/xprop/run-test.sh
index 84b7c4ac4..303c0bb3b 100755
--- a/tests/xprop/run-test.sh
+++ b/tests/xprop/run-test.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+source ../common-env.sh
 set -e
 
 python3 generate.py $@