Merge https://github.com/cliffordwolf/yosys

21 files changed, 406 insertions, 333 deletions

diff --git a/backends/btor/verilog2btor.sh b/backends/btor/verilog2btor.sh
index 1c537d5bd..dfd7f1a85 100755
--- a/backends/btor/verilog2btor.sh
+++ b/backends/btor/verilog2btor.sh
@@ -22,7 +22,7 @@ hierarchy -top $3;
 hierarchy -libdir $DIR;
 hierarchy -check;
 proc;
-opt; opt_const -mux_undef; opt;
+opt; opt_expr -mux_undef; opt;
 rename -hide;;;
 #techmap -map +/pmux2mux.v;;
 splice; opt;
diff --git a/kernel/log.h b/kernel/log.h
index 28baf9886..c0be23b08 100644
--- a/kernel/log.h
+++ b/kernel/log.h
@@ -230,6 +230,32 @@ static inline void log_dump_args_worker(const char *p YS_ATTRIBUTE(unused)) { lo
 void log_dump_val_worker(RTLIL::IdString v);
 void log_dump_val_worker(RTLIL::SigSpec v);
 
+template<typename K, typename T, typename OPS>
+static inline void log_dump_val_worker(dict<K, T, OPS> &v) {
+	log("{");
+	bool first = true;
+	for (auto &it : v) {
+		log(first ? " " : ", ");
+		log_dump_val_worker(it.first);
+		log(": ");
+		log_dump_val_worker(it.second);
+		first = false;
+	}
+	log(" }");
+}
+
+template<typename K, typename OPS>
+static inline void log_dump_val_worker(pool<K, OPS> &v) {
+	log("{");
+	bool first = true;
+	for (auto &it : v) {
+		log(first ? " " : ", ");
+		log_dump_val_worker(it);
+		first = false;
+	}
+	log(" }");
+}
+
 template<typename T>
 static inline void log_dump_val_worker(T *ptr) { log("%p", ptr); }
 
diff --git a/kernel/register.cc b/kernel/register.cc
index 49a67324d..ebe3055ac 100644
--- a/kernel/register.cc
+++ b/kernel/register.cc
@@ -80,6 +80,7 @@ Pass::pre_post_exec_state_t Pass::pre_execute()
 	state.begin_ns = PerformanceTimer::query();
 	state.parent_pass = current_pass;
 	current_pass = this;
+	clear_flags();
 	return state;
 }
 
@@ -99,6 +100,10 @@ void Pass::help()
 	log("\n");
 }
 
+void Pass::clear_flags()
+{
+}
+
 void Pass::cmd_log_args(const std::vector<std::string> &args)
 {
 	if (args.size() <= 1)
@@ -282,6 +287,60 @@ void Pass::call_on_module(RTLIL::Design *design, RTLIL::Module *module, std::vec
 	design->selected_active_module = backup_selected_active_module;
 }
 
+bool ScriptPass::check_label(std::string label, std::string info)
+{
+	if (active_design == nullptr) {
+		log("\n");
+		if (info.empty())
+			log("    %s:\n", label.c_str());
+		else
+			log("    %s:    %s\n", label.c_str(), info.c_str());
+		return true;
+	} else {
+		if (!active_run_from.empty() && active_run_from == active_run_to) {
+			block_active = (label == active_run_from);
+		} else {
+			if (label == active_run_from)
+				block_active = true;
+			if (label == active_run_to)
+				block_active = false;
+		}
+		return block_active;
+	}
+}
+
+void ScriptPass::run(std::string command, std::string info)
+{
+	if (active_design == nullptr) {
+		if (info.empty())
+			log("        %s\n", command.c_str());
+		else
+			log("        %s    %s\n", command.c_str(), info.c_str());
+	} else
+		Pass::call(active_design, command);
+}
+
+void ScriptPass::run_script(RTLIL::Design *design, std::string run_from, std::string run_to)
+{
+	help_mode = false;
+	active_design = design;
+	block_active = run_from.empty();
+	active_run_from = run_from;
+	active_run_to = run_to;
+	script();
+}
+
+void ScriptPass::help_script()
+{
+	clear_flags();
+	help_mode = true;
+	active_design = nullptr;
+	block_active = true;
+	active_run_from.clear();
+	active_run_to.clear();
+	script();
+}
+
 Frontend::Frontend(std::string name, std::string short_help) :
 		Pass(name.rfind("=", 0) == 0 ? name.substr(1) : "read_" + name, short_help),
 		frontend_name(name.rfind("=", 0) == 0 ? name.substr(1) : name)
diff --git a/kernel/register.h b/kernel/register.h
index 0ef07b760..8024c56a0 100644
--- a/kernel/register.h
+++ b/kernel/register.h
@@ -31,6 +31,7 @@ struct Pass
 	virtual ~Pass();
 
 	virtual void help();
+	virtual void clear_flags();
 	virtual void execute(std::vector<std::string> args, RTLIL::Design *design) = 0;
 
 	int call_counter;
@@ -63,6 +64,22 @@ struct Pass
 	static void done_register();
 };
 
+struct ScriptPass : Pass
+{
+	bool block_active, help_mode;
+	RTLIL::Design *active_design;
+	std::string active_run_from, active_run_to;
+
+	ScriptPass(std::string name, std::string short_help = "** document me **") : Pass(name, short_help) { }
+
+	virtual void script() = 0;
+
+	bool check_label(std::string label, std::string info = std::string());
+	void run(std::string command, std::string info = std::string());
+	void run_script(RTLIL::Design *design, std::string run_from = std::string(), std::string run_to = std::string());
+	void help_script();
+};
+
 struct Frontend : Pass
 {
 	// for reading of here documents
diff --git a/kernel/yosys.cc b/kernel/yosys.cc
index 501d94224..8da57fd4e 100644
--- a/kernel/yosys.cc
+++ b/kernel/yosys.cc
@@ -1100,8 +1100,8 @@ struct HistoryPass : public Pass {
 } HistoryPass;
 #endif
 
-struct ScriptPass : public Pass {
-	ScriptPass() : Pass("script", "execute commands from script file") { }
+struct ScriptCmdPass : public Pass {
+	ScriptCmdPass() : Pass("script", "execute commands from script file") { }
 	virtual void help() {
 		log("\n");
 		log("    script <filename> [<from_label>:<to_label>]\n");
@@ -1127,7 +1127,7 @@ struct ScriptPass : public Pass {
 		else
 			extra_args(args, 2, design, false);
 	}
-} ScriptPass;
+} ScriptCmdPass;
 
 YOSYS_NAMESPACE_END
 
diff --git a/manual/APPNOTE_012_Verilog_to_BTOR.tex b/manual/APPNOTE_012_Verilog_to_BTOR.tex
index 245a6b0b8..1bc277876 100644
--- a/manual/APPNOTE_012_Verilog_to_BTOR.tex
+++ b/manual/APPNOTE_012_Verilog_to_BTOR.tex
@@ -208,7 +208,7 @@ read_verilog -sv $1;
 hierarchy -top $3; hierarchy -libdir $DIR;
 hierarchy -check;
 proc; opt;
-opt_const -mux_undef; opt;
+opt_expr -mux_undef; opt;
 rename -hide;;;
 splice; opt;
 memory_dff -wr_only; memory_collect;;
@@ -263,7 +263,7 @@ read_verilog -sv $1;
 hierarchy -top $3; hierarchy -libdir $DIR;
 hierarchy -check;
 proc; opt;
-opt_const -mux_undef; opt;
+opt_expr -mux_undef; opt;
 rename -hide;;;
 splice; opt;
 memory;;
diff --git a/manual/CHAPTER_Optimize.tex b/manual/CHAPTER_Optimize.tex
index d09b3c478..4b09c2231 100644
--- a/manual/CHAPTER_Optimize.tex
+++ b/manual/CHAPTER_Optimize.tex
@@ -15,23 +15,23 @@ passes that each perform a simple optimization:
 \begin{itemize}
 \item Once at the beginning of {\tt opt}:
 \begin{itemize}
-\item {\tt opt\_const}
-\item {\tt opt\_share -nomux}
+\item {\tt opt\_expr}
+\item {\tt opt\_merge -nomux}
 \end{itemize}
 \item Repeat until result is stable:
 \begin{itemize}
 \item {\tt opt\_muxtree}
 \item {\tt opt\_reduce}
-\item {\tt opt\_share}
+\item {\tt opt\_merge}
 \item {\tt opt\_rmdff}
 \item {\tt opt\_clean}
-\item {\tt opt\_const}
+\item {\tt opt\_expr}
 \end{itemize}
 \end{itemize}
 
 The following section describes each of the {\tt opt\_*} passes.
 
-\subsection{The opt\_const pass}
+\subsection{The opt\_expr pass}
 
 This pass performs const folding on the internal combinational cell types
 described in Chap.~\ref{chapter:celllib}. This means a cell with all constant
@@ -57,11 +57,11 @@ this pass can also optimize cells with some constant inputs.
 		$a$ &   1 & $a$ \\
 		  1 & $b$ & $b$ \\
 	\end{tabular}
-	\caption{Const folding rules for {\tt\$\_AND\_} cells as used in {\tt opt\_const}.}
-	\label{tab:opt_const_and}
+	\caption{Const folding rules for {\tt\$\_AND\_} cells as used in {\tt opt\_expr}.}
+	\label{tab:opt_expr_and}
 \end{table}
 
-Table~\ref{tab:opt_const_and} shows the replacement rules used for optimizing
+Table~\ref{tab:opt_expr_and} shows the replacement rules used for optimizing
 an {\tt\$\_AND\_} gate. The first three rules implement the obvious const folding
 rules. Note that `any' might include dynamic values calculated by other parts
 of the circuit. The following three lines propagate undef (X) states.
@@ -76,10 +76,10 @@ an undef value or a 1 and therefore the output can be set to undef.
 The last two lines simply replace an {\tt\$\_AND\_} gate with one constant-1
 input with a buffer.
 
-Besides this basic const folding the {\tt opt\_const} pass can replace 1-bit wide
+Besides this basic const folding the {\tt opt\_expr} pass can replace 1-bit wide
 {\tt \$eq} and {\tt \$ne} cells with buffers or not-gates if one input is constant.
 
-The {\tt opt\_const} pass is very conservative regarding optimizing {\tt \$mux} cells,
+The {\tt opt\_expr} pass is very conservative regarding optimizing {\tt \$mux} cells,
 as these cells are often used to model decision-trees and breaking these trees can
 interfere with other optimizations.
 
@@ -130,7 +130,7 @@ This pass identifies unused signals and cells and removes them from the design.
 creates an \B{unused\_bits} attribute on wires with unused bits. This attribute can be
 used for debugging or by other optimization passes.
 
-\subsection{The opt\_share pass}
+\subsection{The opt\_merge pass}
 
 This pass performs trivial resource sharing. This means that this pass identifies cells
 with identical inputs and replaces them with a single instance of the cell.
diff --git a/manual/CHAPTER_Overview.tex b/manual/CHAPTER_Overview.tex
index 032c0f8c3..964875d57 100644
--- a/manual/CHAPTER_Overview.tex
+++ b/manual/CHAPTER_Overview.tex
@@ -488,8 +488,8 @@ select.cc}, {\tt show.cc}, \dots) and a couple of other small utility libraries.
 \item {\tt passes/} \\
 This directory contains a subdirectory for each pass or group of passes. For example as
 of this writing the directory {\tt passes/opt/} contains the code for seven
-passes: {\tt opt}, {\tt opt\_const}, {\tt opt\_muxtree}, {\tt opt\_reduce},
-{\tt opt\_rmdff}, {\tt opt\_rmunused} and {\tt opt\_share}.
+passes: {\tt opt}, {\tt opt\_expr}, {\tt opt\_muxtree}, {\tt opt\_reduce},
+{\tt opt\_rmdff}, {\tt opt\_rmunused} and {\tt opt\_merge}.
 
 \item {\tt techlibs/} \\
 This directory contains simulation models and standard implementations for the
@@ -513,7 +513,7 @@ Yosys. So it is not needed to add additional commands to a central list of comma
 \end{sloppypar}
 
 Good starting points for reading example source code to learn how to write passes
-are {\tt passes/opt/opt\_rmdff.cc} and {\tt passes/opt/opt\_share.cc}.
+are {\tt passes/opt/opt\_rmdff.cc} and {\tt passes/opt/opt\_merge.cc}.
 
 See the top-level README file for a quick {\it Getting Started} guide and build
 instructions. The Yosys build is based solely on Makefiles.
diff --git a/manual/PRESENTATION_ExSyn.tex b/manual/PRESENTATION_ExSyn.tex
index 1b56374d6..655720ebc 100644
--- a/manual/PRESENTATION_ExSyn.tex
+++ b/manual/PRESENTATION_ExSyn.tex
@@ -144,16 +144,16 @@ The {\tt opt} command implements a series of simple optimizations. It also
 is a macro command that calls other commands:
 
 \begin{lstlisting}[xleftmargin=0.5cm, basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont, language=ys]
-opt_const               # const folding
-opt_share -nomux        # merging identical cells
+opt_expr                # const folding and simple expression rewriting
+opt_merge -nomux        # merging identical cells
 
 do
     opt_muxtree         # remove never-active branches from multiplexer tree
     opt_reduce          # consolidate trees of boolean ops to reduce functions
-    opt_share           # merging identical cells
+    opt_merge           # merging identical cells
     opt_rmdff           # remove/simplify registers with constant inputs
     opt_clean           # remove unused objects (cells, wires) from design
-    opt_const           # const folding
+    opt_expr            # const folding and simple expression rewriting
 while [changed design]
 \end{lstlisting}
 
@@ -161,7 +161,7 @@ The command {\tt clean} can be used as alias for {\tt opt\_clean}. And {\tt ;;}
 can be used as shortcut for {\tt clean}. For example:
 
 \begin{lstlisting}[xleftmargin=0.5cm, basicstyle=\ttfamily\fontsize{8pt}{10pt}\selectfont, language=ys]
-proc; opt; memory; opt_const;; fsm;;
+proc; opt; memory; opt_expr;; fsm;;
 \end{lstlisting}
 \end{frame}
 
diff --git a/passes/memory/memory_share.cc b/passes/memory/memory_share.cc
index 3a6fd0b44..ab9edb6e7 100644
--- a/passes/memory/memory_share.cc
+++ b/passes/memory/memory_share.cc
@@ -746,7 +746,7 @@ struct MemorySharePass : public Pass {
 		log("\n");
 		log("Note that in addition to the algorithms implemented in this pass, the $memrd\n");
 		log("and $memwr cells are also subject to generic resource sharing passes (and other\n");
-		log("optimizations) such as opt_share.\n");
+		log("optimizations) such as \"share\" and \"opt_merge\".\n");
 		log("\n");
 	}
 	virtual void execute(std::vector<std::string> args, RTLIL::Design *design) {
diff --git a/passes/opt/Makefile.inc b/passes/opt/Makefile.inc
index 43defb788..a8b1537bb 100644
--- a/passes/opt/Makefile.inc
+++ b/passes/opt/Makefile.inc
@@ -1,11 +1,11 @@
 
 OBJS += passes/opt/opt.o
-OBJS += passes/opt/opt_share.o
+OBJS += passes/opt/opt_merge.o
 OBJS += passes/opt/opt_muxtree.o
 OBJS += passes/opt/opt_reduce.o
 OBJS += passes/opt/opt_rmdff.o
 OBJS += passes/opt/opt_clean.o
-OBJS += passes/opt/opt_const.o
+OBJS += passes/opt/opt_expr.o
 
 ifneq ($(SMALL),1)
 OBJS += passes/opt/share.o
diff --git a/passes/opt/opt.cc b/passes/opt/opt.cc
index f5389d8ee..c25adac97 100644
--- a/passes/opt/opt.cc
+++ b/passes/opt/opt.cc
@@ -37,23 +37,23 @@ struct OptPass : public Pass {
 		log("a series of trivial optimizations and cleanups. This pass executes the other\n");
 		log("passes in the following order:\n");
 		log("\n");
-		log("    opt_const [-mux_undef] [-mux_bool] [-undriven] [-clkinv] [-fine] [-full] [-keepdc]\n");
-		log("    opt_share [-share_all] -nomux\n");
+		log("    opt_expr [-mux_undef] [-mux_bool] [-undriven] [-clkinv] [-fine] [-full] [-keepdc]\n");
+		log("    opt_merge [-share_all] -nomux\n");
 		log("\n");
 		log("    do\n");
 		log("        opt_muxtree\n");
 		log("        opt_reduce [-fine] [-full]\n");
-		log("        opt_share [-share_all]\n");
+		log("        opt_merge [-share_all]\n");
 		log("        opt_rmdff\n");
 		log("        opt_clean [-purge]\n");
-		log("        opt_const [-mux_undef] [-mux_bool] [-undriven] [-clkinv] [-fine] [-full] [-keepdc]\n");
+		log("        opt_expr [-mux_undef] [-mux_bool] [-undriven] [-clkinv] [-fine] [-full] [-keepdc]\n");
 		log("    while <changed design>\n");
 		log("\n");
 		log("When called with -fast the following script is used instead:\n");
 		log("\n");
 		log("    do\n");
-		log("        opt_const [-mux_undef] [-mux_bool] [-undriven] [-clkinv] [-fine] [-full] [-keepdc]\n");
-		log("        opt_share [-share_all]\n");
+		log("        opt_expr [-mux_undef] [-mux_bool] [-undriven] [-clkinv] [-fine] [-full] [-keepdc]\n");
+		log("        opt_merge [-share_all]\n");
 		log("        opt_rmdff\n");
 		log("        opt_clean [-purge]\n");
 		log("    while <changed design in opt_rmdff>\n");
@@ -66,9 +66,9 @@ struct OptPass : public Pass {
 	virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
 	{
 		std::string opt_clean_args;
-		std::string opt_const_args;
+		std::string opt_expr_args;
 		std::string opt_reduce_args;
-		std::string opt_share_args;
+		std::string opt_merge_args;
 		bool fast_mode = false;
 
 		log_header("Executing OPT pass (performing simple optimizations).\n");
@@ -81,37 +81,37 @@ struct OptPass : public Pass {
 				continue;
 			}
 			if (args[argidx] == "-mux_undef") {
-				opt_const_args += " -mux_undef";
+				opt_expr_args += " -mux_undef";
 				continue;
 			}
 			if (args[argidx] == "-mux_bool") {
-				opt_const_args += " -mux_bool";
+				opt_expr_args += " -mux_bool";
 				continue;
 			}
 			if (args[argidx] == "-undriven") {
-				opt_const_args += " -undriven";
+				opt_expr_args += " -undriven";
 				continue;
 			}
 			if (args[argidx] == "-clkinv") {
-				opt_const_args += " -clkinv";
+				opt_expr_args += " -clkinv";
 				continue;
 			}
 			if (args[argidx] == "-fine") {
-				opt_const_args += " -fine";
+				opt_expr_args += " -fine";
 				opt_reduce_args += " -fine";
 				continue;
 			}
 			if (args[argidx] == "-full") {
-				opt_const_args += " -full";
+				opt_expr_args += " -full";
 				opt_reduce_args += " -full";
 				continue;
 			}
 			if (args[argidx] == "-keepdc") {
-				opt_const_args += " -keepdc";
+				opt_expr_args += " -keepdc";
 				continue;
 			}
 			if (args[argidx] == "-share_all") {
-				opt_share_args += " -share_all";
+				opt_merge_args += " -share_all";
 				continue;
 			}
 			if (args[argidx] == "-fast") {
@@ -125,8 +125,8 @@ struct OptPass : public Pass {
 		if (fast_mode)
 		{
 			while (1) {
-				Pass::call(design, "opt_const" + opt_const_args);
-				Pass::call(design, "opt_share" + opt_share_args);
+				Pass::call(design, "opt_expr" + opt_expr_args);
+				Pass::call(design, "opt_merge" + opt_merge_args);
 				design->scratchpad_unset("opt.did_something");
 				Pass::call(design, "opt_rmdff");
 				if (design->scratchpad_get_bool("opt.did_something") == false)
@@ -138,16 +138,16 @@ struct OptPass : public Pass {
 		}
 		else
 		{
-			Pass::call(design, "opt_const" + opt_const_args);
-			Pass::call(design, "opt_share -nomux" + opt_share_args);
+			Pass::call(design, "opt_expr" + opt_expr_args);
+			Pass::call(design, "opt_merge -nomux" + opt_merge_args);
 			while (1) {
 				design->scratchpad_unset("opt.did_something");
 				Pass::call(design, "opt_muxtree");
 				Pass::call(design, "opt_reduce" + opt_reduce_args);
-				Pass::call(design, "opt_share" + opt_share_args);
+				Pass::call(design, "opt_merge" + opt_merge_args);
 				Pass::call(design, "opt_rmdff");
 				Pass::call(design, "opt_clean" + opt_clean_args);
-				Pass::call(design, "opt_const" + opt_const_args);
+				Pass::call(design, "opt_expr" + opt_expr_args);
 				if (design->scratchpad_get_bool("opt.did_something") == false)
 					break;
 				log_header("Rerunning OPT passes. (Maybe there is more to do..)\n");
diff --git a/passes/opt/opt_const.cc b/passes/opt/opt_expr.cc
index 0fcacf0a8..9e713935d 100644
--- a/passes/opt/opt_const.cc
+++ b/passes/opt/opt_expr.cc
@@ -179,7 +179,7 @@ bool group_cell_inputs(RTLIL::Module *module, RTLIL::Cell *cell, bool commutativ
 		log("\n");
 	}
 
-	cover_list("opt.opt_const.fine.group", "$not", "$pos", "$and", "$or", "$xor", "$xnor", cell->type.str());
+	cover_list("opt.opt_expr.fine.group", "$not", "$pos", "$and", "$or", "$xor", "$xnor", cell->type.str());
 
 	module->remove(cell);
 	did_something = true;
@@ -304,7 +304,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 
 	for (auto cell : cells.sorted)
 	{
-#define ACTION_DO(_p_, _s_) do { cover("opt.opt_const.action_" S__LINE__); replace_cell(assign_map, module, cell, input.as_string(), _p_, _s_); goto next_cell; } while (0)
+#define ACTION_DO(_p_, _s_) do { cover("opt.opt_expr.action_" S__LINE__); replace_cell(assign_map, module, cell, input.as_string(), _p_, _s_); goto next_cell; } while (0)
 #define ACTION_DO_Y(_v_) ACTION_DO("\\Y", RTLIL::SigSpec(RTLIL::State::S ## _v_))
 
 		if (clkinv)
@@ -366,7 +366,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 					}
 
 				if (new_a != RTLIL::State::Sm && RTLIL::SigSpec(new_a) != sig_a) {
-					cover("opt.opt_const.fine.$reduce_and");
+					cover("opt.opt_expr.fine.$reduce_and");
 					log("Replacing port A of %s cell `%s' in module `%s' with constant driver: %s -> %s\n",
 							cell->type.c_str(), cell->name.c_str(), module->name.c_str(), log_signal(sig_a), log_signal(new_a));
 					cell->setPort("\\A", sig_a = new_a);
@@ -392,7 +392,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 					}
 
 				if (new_a != RTLIL::State::Sm && RTLIL::SigSpec(new_a) != sig_a) {
-					cover_list("opt.opt_const.fine.A", "$logic_not", "$logic_and", "$logic_or", "$reduce_or", "$reduce_bool", cell->type.str());
+					cover_list("opt.opt_expr.fine.A", "$logic_not", "$logic_and", "$logic_or", "$reduce_or", "$reduce_bool", cell->type.str());
 					log("Replacing port A of %s cell `%s' in module `%s' with constant driver: %s -> %s\n",
 							cell->type.c_str(), cell->name.c_str(), module->name.c_str(), log_signal(sig_a), log_signal(new_a));
 					cell->setPort("\\A", sig_a = new_a);
@@ -418,7 +418,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 					}
 
 				if (new_b != RTLIL::State::Sm && RTLIL::SigSpec(new_b) != sig_b) {
-					cover_list("opt.opt_const.fine.B", "$logic_and", "$logic_or", cell->type.str());
+					cover_list("opt.opt_expr.fine.B", "$logic_and", "$logic_or", cell->type.str());
 					log("Replacing port B of %s cell `%s' in module `%s' with constant driver: %s -> %s\n",
 							cell->type.c_str(), cell->name.c_str(), module->name.c_str(), log_signal(sig_b), log_signal(new_b));
 					cell->setPort("\\B", sig_b = new_b);
@@ -429,13 +429,13 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 		}
 
 		if (cell->type == "$logic_or" && (assign_map(cell->getPort("\\A")) == RTLIL::State::S1 || assign_map(cell->getPort("\\B")) == RTLIL::State::S1)) {
-			cover("opt.opt_const.one_high");
+			cover("opt.opt_expr.one_high");
 			replace_cell(assign_map, module, cell, "one high", "\\Y", RTLIL::State::S1);
 			goto next_cell;
 		}
 
 		if (cell->type == "$logic_and" && (assign_map(cell->getPort("\\A")) == RTLIL::State::S0 || assign_map(cell->getPort("\\B")) == RTLIL::State::S0)) {
-			cover("opt.opt_const.one_low");
+			cover("opt.opt_expr.one_low");
 			replace_cell(assign_map, module, cell, "one low", "\\Y", RTLIL::State::S0);
 			goto next_cell;
 		}
@@ -462,7 +462,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 
 			if (0) {
 		found_the_x_bit:
-				cover_list("opt.opt_const.xbit", "$reduce_xor", "$reduce_xnor", "$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx",
+				cover_list("opt.opt_expr.xbit", "$reduce_xor", "$reduce_xnor", "$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx",
 						"$lt", "$le", "$ge", "$gt", "$neg", "$add", "$sub", "$mul", "$div", "$mod", "$pow", cell->type.str());
 				if (cell->type == "$reduce_xor" || cell->type == "$reduce_xnor" ||
 						cell->type == "$lt" || cell->type == "$le" || cell->type == "$ge" || cell->type == "$gt")
@@ -475,13 +475,13 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 
 		if ((cell->type == "$_NOT_" || cell->type == "$not" || cell->type == "$logic_not") && cell->getPort("\\Y").size() == 1 &&
 				invert_map.count(assign_map(cell->getPort("\\A"))) != 0) {
-			cover_list("opt.opt_const.invert.double", "$_NOT_", "$not", "$logic_not", cell->type.str());
+			cover_list("opt.opt_expr.invert.double", "$_NOT_", "$not", "$logic_not", cell->type.str());
 			replace_cell(assign_map, module, cell, "double_invert", "\\Y", invert_map.at(assign_map(cell->getPort("\\A"))));
 			goto next_cell;
 		}
 
 		if ((cell->type == "$_MUX_" || cell->type == "$mux") && invert_map.count(assign_map(cell->getPort("\\S"))) != 0) {
-			cover_list("opt.opt_const.invert.muxsel", "$_MUX_", "$mux", cell->type.str());
+			cover_list("opt.opt_expr.invert.muxsel", "$_MUX_", "$mux", cell->type.str());
 			log("Optimizing away select inverter for %s cell `%s' in module `%s'.\n", log_id(cell->type), log_id(cell), log_id(module));
 			RTLIL::SigSpec tmp = cell->getPort("\\A");
 			cell->setPort("\\A", cell->getPort("\\B"));
@@ -564,7 +564,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 			if (input.match("  1")) ACTION_DO("\\Y", input.extract(1, 1));
 			if (input.match("01 ")) ACTION_DO("\\Y", input.extract(0, 1));
 			if (input.match("10 ")) {
-				cover("opt.opt_const.mux_to_inv");
+				cover("opt.opt_expr.mux_to_inv");
 				cell->type = "$_NOT_";
 				cell->setPort("\\A", input.extract(0, 1));
 				cell->unsetPort("\\B");
@@ -599,7 +599,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 			log_assert(GetSize(a) == GetSize(b));
 			for (int i = 0; i < GetSize(a); i++) {
 				if (a[i].wire == NULL && b[i].wire == NULL && a[i] != b[i] && a[i].data <= RTLIL::State::S1 && b[i].data <= RTLIL::State::S1) {
-					cover_list("opt.opt_const.eqneq.isneq", "$eq", "$ne", "$eqx", "$nex", cell->type.str());
+					cover_list("opt.opt_expr.eqneq.isneq", "$eq", "$ne", "$eqx", "$nex", cell->type.str());
 					RTLIL::SigSpec new_y = RTLIL::SigSpec((cell->type == "$eq" || cell->type == "$eqx") ?  RTLIL::State::S0 : RTLIL::State::S1);
 					new_y.extend_u0(cell->parameters["\\Y_WIDTH"].as_int(), false);
 					replace_cell(assign_map, module, cell, "isneq", "\\Y", new_y);
@@ -612,7 +612,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 			}
 
 			if (new_a.size() == 0) {
-				cover_list("opt.opt_const.eqneq.empty", "$eq", "$ne", "$eqx", "$nex", cell->type.str());
+				cover_list("opt.opt_expr.eqneq.empty", "$eq", "$ne", "$eqx", "$nex", cell->type.str());
 				RTLIL::SigSpec new_y = RTLIL::SigSpec((cell->type == "$eq" || cell->type == "$eqx") ?  RTLIL::State::S1 : RTLIL::State::S0);
 				new_y.extend_u0(cell->parameters["\\Y_WIDTH"].as_int(), false);
 				replace_cell(assign_map, module, cell, "empty", "\\Y", new_y);
@@ -620,7 +620,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 			}
 
 			if (new_a.size() < a.size() || new_b.size() < b.size()) {
-				cover_list("opt.opt_const.eqneq.resize", "$eq", "$ne", "$eqx", "$nex", cell->type.str());
+				cover_list("opt.opt_expr.eqneq.resize", "$eq", "$ne", "$eqx", "$nex", cell->type.str());
 				cell->setPort("\\A", new_a);
 				cell->setPort("\\B", new_b);
 				cell->parameters["\\A_WIDTH"] = new_a.size();
@@ -635,7 +635,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 			RTLIL::SigSpec b = assign_map(cell->getPort("\\B"));
 
 			if (a.is_fully_const() && !b.is_fully_const()) {
-				cover_list("opt.opt_const.eqneq.swapconst", "$eq", "$ne", cell->type.str());
+				cover_list("opt.opt_expr.eqneq.swapconst", "$eq", "$ne", cell->type.str());
 				cell->setPort("\\A", b);
 				cell->setPort("\\B", a);
 				std::swap(a, b);
@@ -646,7 +646,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 					RTLIL::SigSpec input = b;
 					ACTION_DO("\\Y", cell->getPort("\\A"));
 				} else {
-					cover_list("opt.opt_const.eqneq.isnot", "$eq", "$ne", cell->type.str());
+					cover_list("opt.opt_expr.eqneq.isnot", "$eq", "$ne", cell->type.str());
 					log("Replacing %s cell `%s' in module `%s' with inverter.\n", log_id(cell->type), log_id(cell), log_id(module));
 					cell->type = "$not";
 					cell->parameters.erase("\\B_WIDTH");
@@ -661,7 +661,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 		if ((cell->type == "$eq" || cell->type == "$ne") &&
 				(assign_map(cell->getPort("\\A")).is_fully_zero() || assign_map(cell->getPort("\\B")).is_fully_zero()))
 		{
-			cover_list("opt.opt_const.eqneq.cmpzero", "$eq", "$ne", cell->type.str());
+			cover_list("opt.opt_expr.eqneq.cmpzero", "$eq", "$ne", cell->type.str());
 			log("Replacing %s cell `%s' in module `%s' with %s.\n", log_id(cell->type), log_id(cell),
 					log_id(module), "$eq" ? "$logic_not" : "$reduce_bool");
 			cell->type = cell->type == "$eq" ? "$logic_not" : "$reduce_bool";
@@ -699,7 +699,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 					sig_y[i] = sig_a[GetSize(sig_a)-1];
 			}
 
-			cover_list("opt.opt_const.constshift", "$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx", cell->type.str());
+			cover_list("opt.opt_expr.constshift", "$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx", cell->type.str());
 
 			log("Replacing %s cell `%s' (B=%s, SHR=%d) in module `%s' with fixed wiring: %s\n",
 					log_id(cell->type), log_id(cell), log_signal(assign_map(cell->getPort("\\B"))), shift_bits, log_id(module), log_signal(sig_y));
@@ -760,9 +760,9 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 			if (identity_wrt_a || identity_wrt_b)
 			{
 				if (identity_wrt_a)
-					cover_list("opt.opt_const.identwrt.a", "$add", "$sub", "$or", "$xor", "$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx", "$mul", "$div", cell->type.str());
+					cover_list("opt.opt_expr.identwrt.a", "$add", "$sub", "$or", "$xor", "$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx", "$mul", "$div", cell->type.str());
 				if (identity_wrt_b)
-					cover_list("opt.opt_const.identwrt.b", "$add", "$sub", "$or", "$xor", "$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx", "$mul", "$div", cell->type.str());
+					cover_list("opt.opt_expr.identwrt.b", "$add", "$sub", "$or", "$xor", "$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx", "$mul", "$div", cell->type.str());
 
 				log("Replacing %s cell `%s' in module `%s' with identity for port %c.\n",
 					cell->type.c_str(), cell->name.c_str(), module->name.c_str(), identity_wrt_a ? 'A' : 'B');
@@ -786,14 +786,14 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 
 		if (mux_bool && (cell->type == "$mux" || cell->type == "$_MUX_") &&
 				cell->getPort("\\A") == RTLIL::SigSpec(0, 1) && cell->getPort("\\B") == RTLIL::SigSpec(1, 1)) {
-			cover_list("opt.opt_const.mux_bool", "$mux", "$_MUX_", cell->type.str());
+			cover_list("opt.opt_expr.mux_bool", "$mux", "$_MUX_", cell->type.str());
 			replace_cell(assign_map, module, cell, "mux_bool", "\\Y", cell->getPort("\\S"));
 			goto next_cell;
 		}
 
 		if (mux_bool && (cell->type == "$mux" || cell->type == "$_MUX_") &&
 				cell->getPort("\\A") == RTLIL::SigSpec(1, 1) && cell->getPort("\\B") == RTLIL::SigSpec(0, 1)) {
-			cover_list("opt.opt_const.mux_invert", "$mux", "$_MUX_", cell->type.str());
+			cover_list("opt.opt_expr.mux_invert", "$mux", "$_MUX_", cell->type.str());
 			log("Replacing %s cell `%s' in module `%s' with inverter.\n", log_id(cell->type), log_id(cell), log_id(module));
 			cell->setPort("\\A", cell->getPort("\\S"));
 			cell->unsetPort("\\B");
@@ -812,7 +812,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 		}
 
 		if (consume_x && mux_bool && (cell->type == "$mux" || cell->type == "$_MUX_") && cell->getPort("\\A") == RTLIL::SigSpec(0, 1)) {
-			cover_list("opt.opt_const.mux_and", "$mux", "$_MUX_", cell->type.str());
+			cover_list("opt.opt_expr.mux_and", "$mux", "$_MUX_", cell->type.str());
 			log("Replacing %s cell `%s' in module `%s' with and-gate.\n", log_id(cell->type), log_id(cell), log_id(module));
 			cell->setPort("\\A", cell->getPort("\\S"));
 			cell->unsetPort("\\S");
@@ -832,7 +832,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 		}
 
 		if (consume_x && mux_bool && (cell->type == "$mux" || cell->type == "$_MUX_") && cell->getPort("\\B") == RTLIL::SigSpec(1, 1)) {
-			cover_list("opt.opt_const.mux_or", "$mux", "$_MUX_", cell->type.str());
+			cover_list("opt.opt_expr.mux_or", "$mux", "$_MUX_", cell->type.str());
 			log("Replacing %s cell `%s' in module `%s' with or-gate.\n", log_id(cell->type), log_id(cell), log_id(module));
 			cell->setPort("\\B", cell->getPort("\\S"));
 			cell->unsetPort("\\S");
@@ -856,7 +856,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 			int width = cell->getPort("\\A").size();
 			if ((cell->getPort("\\A").is_fully_undef() && cell->getPort("\\B").is_fully_undef()) ||
 					cell->getPort("\\S").is_fully_undef()) {
-				cover_list("opt.opt_const.mux_undef", "$mux", "$pmux", cell->type.str());
+				cover_list("opt.opt_expr.mux_undef", "$mux", "$pmux", cell->type.str());
 				replace_cell(assign_map, module, cell, "mux_undef", "\\Y", cell->getPort("\\A"));
 				goto next_cell;
 			}
@@ -875,17 +875,17 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 				new_s = new_s.extract(0, new_s.size()-1);
 			}
 			if (new_s.size() == 0) {
-				cover_list("opt.opt_const.mux_empty", "$mux", "$pmux", cell->type.str());
+				cover_list("opt.opt_expr.mux_empty", "$mux", "$pmux", cell->type.str());
 				replace_cell(assign_map, module, cell, "mux_empty", "\\Y", new_a);
 				goto next_cell;
 			}
 			if (new_a == RTLIL::SigSpec(RTLIL::State::S0) && new_b == RTLIL::SigSpec(RTLIL::State::S1)) {
-				cover_list("opt.opt_const.mux_sel01", "$mux", "$pmux", cell->type.str());
+				cover_list("opt.opt_expr.mux_sel01", "$mux", "$pmux", cell->type.str());
 				replace_cell(assign_map, module, cell, "mux_sel01", "\\Y", new_s);
 				goto next_cell;
 			}
 			if (cell->getPort("\\S").size() != new_s.size()) {
-				cover_list("opt.opt_const.mux_reduce", "$mux", "$pmux", cell->type.str());
+				cover_list("opt.opt_expr.mux_reduce", "$mux", "$pmux", cell->type.str());
 				log("Optimized away %d select inputs of %s cell `%s' in module `%s'.\n",
 						GetSize(cell->getPort("\\S")) - GetSize(new_s), log_id(cell->type), log_id(cell), log_id(module));
 				cell->setPort("\\A", new_a);
@@ -911,7 +911,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 				RTLIL::SigSpec y(RTLIL::const_ ## _t(a.as_const(), dummy_arg, \
 						cell->parameters["\\A_SIGNED"].as_bool(), false, \
 						cell->parameters["\\Y_WIDTH"].as_int())); \
-				cover("opt.opt_const.const.$" #_t); \
+				cover("opt.opt_expr.const.$" #_t); \
 				replace_cell(assign_map, module, cell, stringf("%s", log_signal(a)), "\\Y", y); \
 				goto next_cell; \
 			} \
@@ -926,7 +926,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 						cell->parameters["\\A_SIGNED"].as_bool(), \
 						cell->parameters["\\B_SIGNED"].as_bool(), \
 						cell->parameters["\\Y_WIDTH"].as_int())); \
-				cover("opt.opt_const.const.$" #_t); \
+				cover("opt.opt_expr.const.$" #_t); \
 				replace_cell(assign_map, module, cell, stringf("%s, %s", log_signal(a), log_signal(b)), "\\Y", y); \
 				goto next_cell; \
 			} \
@@ -1002,7 +1002,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 
 				if (a_val == 0)
 				{
-					cover("opt.opt_const.mul_shift.zero");
+					cover("opt.opt_expr.mul_shift.zero");
 
 					log("Replacing multiply-by-zero cell `%s' in module `%s' with zero-driver.\n",
 							cell->name.c_str(), module->name.c_str());
@@ -1018,9 +1018,9 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 					if (a_val == (1 << i))
 					{
 						if (swapped_ab)
-							cover("opt.opt_const.mul_shift.swapped");
+							cover("opt.opt_expr.mul_shift.swapped");
 						else
-							cover("opt.opt_const.mul_shift.unswapped");
+							cover("opt.opt_expr.mul_shift.unswapped");
 
 						log("Replacing multiply-by-%d cell `%s' in module `%s' with shift-by-%d.\n",
 								a_val, cell->name.c_str(), module->name.c_str(), i);
@@ -1056,15 +1056,16 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 	}
 }
 
-struct OptConstPass : public Pass {
-	OptConstPass() : Pass("opt_const", "perform const folding") { }
+struct OptExprPass : public Pass {
+	OptExprPass() : Pass("opt_expr", "perform const folding and simple expression rewriting") { }
 	virtual void help()
 	{
 		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
 		log("\n");
-		log("    opt_const [options] [selection]\n");
+		log("    opt_expr [options] [selection]\n");
 		log("\n");
 		log("This pass performs const folding on internal cell types with constant inputs.\n");
+		log("It also performs some simple expression rewritring.\n");
 		log("\n");
 		log("    -mux_undef\n");
 		log("        remove 'undef' inputs from $mux, $pmux and $_MUX_ cells\n");
@@ -1100,7 +1101,7 @@ struct OptConstPass : public Pass {
 		bool do_fine = false;
 		bool keepdc = false;
 
-		log_header("Executing OPT_CONST pass (perform const folding).\n");
+		log_header("Executing OPT_EXPR pass (perform const folding).\n");
 		log_push();
 
 		size_t argidx;
@@ -1158,6 +1159,6 @@ struct OptConstPass : public Pass {
 
 		log_pop();
 	}
-} OptConstPass;
+} OptExprPass;
 
 PRIVATE_NAMESPACE_END
diff --git a/passes/opt/opt_share.cc b/passes/opt/opt_merge.cc
index 46752e43b..07019aac9 100644
--- a/passes/opt/opt_share.cc
+++ b/passes/opt/opt_merge.cc
@@ -31,7 +31,7 @@
 USING_YOSYS_NAMESPACE
 PRIVATE_NAMESPACE_BEGIN
 
-struct OptShareWorker
+struct OptMergeWorker
 {
 	RTLIL::Design *design;
 	RTLIL::Module *module;
@@ -45,6 +45,29 @@ struct OptShareWorker
 	dict<const RTLIL::Cell*, std::string> cell_hash_cache;
 #endif
 
+	static void sort_pmux_conn(dict<RTLIL::IdString, RTLIL::SigSpec> &conn)
+	{
+		SigSpec sig_s = conn.at("\\S");
+		SigSpec sig_b = conn.at("\\B");
+
+		int s_width = GetSize(sig_s);
+		int width = GetSize(sig_b) / s_width;
+
+		vector<pair<SigBit, SigSpec>> sb_pairs;
+		for (int i = 0; i < s_width; i++)
+			sb_pairs.push_back(pair<SigBit, SigSpec>(sig_s[i], sig_b.extract(i*width, width)));
+
+		std::sort(sb_pairs.begin(), sb_pairs.end());
+
+		conn["\\S"] = SigSpec();
+		conn["\\B"] = SigSpec();
+
+		for (auto &it : sb_pairs) {
+			conn["\\S"].append(it.first);
+			conn["\\B"].append(it.second);
+		}
+	}
+
 #ifdef USE_CELL_HASH_CACHE
 	std::string int_to_hash_string(unsigned int v)
 	{
@@ -91,25 +114,40 @@ struct OptShareWorker
 			assign_map.apply(alt_conn.at("\\A"));
 			alt_conn.at("\\A").sort_and_unify();
 			conn = &alt_conn;
+		} else
+		if (cell->type == "$pmux") {
+			alt_conn = *conn;
+			assign_map.apply(alt_conn.at("\\A"));
+			assign_map.apply(alt_conn.at("\\B"));
+			assign_map.apply(alt_conn.at("\\S"));
+			sort_pmux_conn(alt_conn);
+			conn = &alt_conn;
 		}
 
+		vector<string> hash_conn_strings;
+
 		for (auto &it : *conn) {
 			if (cell->output(it.first))
 				continue;
 			RTLIL::SigSpec sig = it.second;
 			assign_map.apply(sig);
-			hash_string += "C " + it.first.str() + "=";
+			string s = "C " + it.first.str() + "=";
 			for (auto &chunk : sig.chunks()) {
 				if (chunk.wire)
-					hash_string += "{" + chunk.wire->name.str() + " " +
+					s += "{" + chunk.wire->name.str() + " " +
 							int_to_hash_string(chunk.offset) + " " +
 							int_to_hash_string(chunk.width) + "}";
 				else
-					hash_string += RTLIL::Const(chunk.data).as_string();
+					s += RTLIL::Const(chunk.data).as_string();
 			}
-			hash_string += "\n";
+			hash_conn_strings.push_back(s + "\n");
 		}
 
+		std::sort(hash_conn_strings.begin(), hash_conn_strings.end());
+
+		for (auto it : hash_conn_strings)
+			hash_string += it;
+
 		cell_hash_cache[cell] = sha1(hash_string);
 		return cell_hash_cache[cell];
 	}
@@ -171,6 +209,10 @@ struct OptShareWorker
 		if (cell1->type == "$reduce_and" || cell1->type == "$reduce_or" || cell1->type == "$reduce_bool") {
 			conn1["\\A"].sort_and_unify();
 			conn2["\\A"].sort_and_unify();
+		} else
+		if (cell1->type == "$pmux") {
+			sort_pmux_conn(conn1);
+			sort_pmux_conn(conn2);
 		}
 
 		if (conn1 != conn2) {
@@ -212,14 +254,14 @@ struct OptShareWorker
 	}
 
 	struct CompareCells {
-		OptShareWorker *that;
-		CompareCells(OptShareWorker *that) : that(that) {}
+		OptMergeWorker *that;
+		CompareCells(OptMergeWorker *that) : that(that) {}
 		bool operator()(const RTLIL::Cell *cell1, const RTLIL::Cell *cell2) const {
 			return that->compare_cells(cell1, cell2);
 		}
 	};
 
-	OptShareWorker(RTLIL::Design *design, RTLIL::Module *module, bool mode_nomux, bool mode_share_all) :
+	OptMergeWorker(RTLIL::Design *design, RTLIL::Module *module, bool mode_nomux, bool mode_share_all) :
 		design(design), module(module), assign_map(module), mode_share_all(mode_share_all)
 	{
 		total_count = 0;
@@ -286,13 +328,13 @@ struct OptShareWorker
 	}
 };
 
-struct OptSharePass : public Pass {
-	OptSharePass() : Pass("opt_share", "consolidate identical cells") { }
+struct OptMergePass : public Pass {
+	OptMergePass() : Pass("opt_merge", "consolidate identical cells") { }
 	virtual void help()
 	{
 		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
 		log("\n");
-		log("    opt_share [options] [selection]\n");
+		log("    opt_merge [options] [selection]\n");
 		log("\n");
 		log("This pass identifies cells with identical type and input signals. Such cells\n");
 		log("are then merged to one cell.\n");
@@ -306,7 +348,7 @@ struct OptSharePass : public Pass {
 	}
 	virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
 	{
-		log_header("Executing OPT_SHARE pass (detect identical cells).\n");
+		log_header("Executing OPT_MERGE pass (detect identical cells).\n");
 
 		bool mode_nomux = false;
 		bool mode_share_all = false;
@@ -328,7 +370,7 @@ struct OptSharePass : public Pass {
 
 		int total_count = 0;
 		for (auto module : design->selected_modules()) {
-			OptShareWorker worker(design, module, mode_nomux, mode_share_all);
+			OptMergeWorker worker(design, module, mode_nomux, mode_share_all);
 			total_count += worker.total_count;
 		}
 
@@ -336,6 +378,6 @@ struct OptSharePass : public Pass {
 			design->scratchpad_set_bool("opt.did_something", true);
 		log("Removed a total of %d cells.\n", total_count);
 	}
-} OptSharePass;
+} OptMergePass;
 
 PRIVATE_NAMESPACE_END
diff --git a/passes/proc/proc_rmdead.cc b/passes/proc/proc_rmdead.cc
index f60d4b30d..af17e8d38 100644
--- a/passes/proc/proc_rmdead.cc
+++ b/passes/proc/proc_rmdead.cc
@@ -51,8 +51,8 @@ void proc_rmdead(RTLIL::SwitchRule *sw, int &counter)
 				counter++;
 				continue;
 			}
-			if (pool.empty())
-				sw->cases[i]->compare.clear();
+			// if (pool.empty())
+			// 	sw->cases[i]->compare.clear();
 		}
 
 		for (auto switch_it : sw->cases[i]->switches)
diff --git a/passes/sat/miter.cc b/passes/sat/miter.cc
index 682299ef2..e809425c8 100644
--- a/passes/sat/miter.cc
+++ b/passes/sat/miter.cc
@@ -254,7 +254,7 @@ void create_miter_equiv(struct Pass *that, std::vector<std::string> args, RTLIL:
 
 	if (flag_flatten) {
 		log_push();
-		Pass::call_on_module(design, miter_module, "flatten; opt_const -keepdc -undriven;;");
+		Pass::call_on_module(design, miter_module, "flatten; opt_expr -keepdc -undriven;;");
 		log_pop();
 	}
 }
@@ -327,7 +327,7 @@ void create_miter_assert(struct Pass *that, std::vector<std::string> args, RTLIL
 
 	if (flag_flatten) {
 		log_push();
-		Pass::call_on_module(design, module, "opt_const -keepdc -undriven;;");
+		Pass::call_on_module(design, module, "opt_expr -keepdc -undriven;;");
 		log_pop();
 	}
 }
@@ -361,7 +361,7 @@ struct MiterPass : public Pass {
 		log("        also create an 'assert' cell that checks if trigger is always low.\n");
 		log("\n");
 		log("    -flatten\n");
-		log("        call 'flatten; opt_const -keepdc -undriven;;' on the miter circuit.\n");
+		log("        call 'flatten; opt_expr -keepdc -undriven;;' on the miter circuit.\n");
 		log("\n");
 		log("\n");
 		log("    miter -assert [options] module [miter_name]\n");
@@ -375,7 +375,7 @@ struct MiterPass : public Pass {
 		log("        keep module output ports.\n");
 		log("\n");
 		log("    -flatten\n");
-		log("        call 'flatten; opt_const -keepdc -undriven;;' on the miter circuit.\n");
+		log("        call 'flatten; opt_expr -keepdc -undriven;;' on the miter circuit.\n");
 		log("\n");
 	}
 	virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
diff --git a/techlibs/common/prep.cc b/techlibs/common/prep.cc
index 8bae920d0..911737947 100644
--- a/techlibs/common/prep.cc
+++ b/techlibs/common/prep.cc
@@ -69,7 +69,7 @@ struct PrepPass : public Pass {
 		log("\n");
 		log("    prep:\n");
 		log("        proc\n");
-		log("        opt_const\n");
+		log("        opt_expr -keepdc\n");
 		log("        opt_clean\n");
 		log("        check\n");
 		log("        opt -keepdc\n");
@@ -134,7 +134,7 @@ struct PrepPass : public Pass {
 		if (check_label(active, run_from, run_to, "coarse"))
 		{
 			Pass::call(design, "proc");
-			Pass::call(design, "opt_const");
+			Pass::call(design, "opt_expr -keepdc");
 			Pass::call(design, "opt_clean");
 			Pass::call(design, "check");
 			Pass::call(design, "opt -keepdc");
diff --git a/techlibs/common/synth.cc b/techlibs/common/synth.cc
index 83d00f328..8eb1aeba4 100644
--- a/techlibs/common/synth.cc
+++ b/techlibs/common/synth.cc
@@ -25,22 +25,11 @@
 USING_YOSYS_NAMESPACE
 PRIVATE_NAMESPACE_BEGIN
 
-bool check_label(bool &active, std::string run_from, std::string run_to, std::string label)
+struct SynthPass : public ScriptPass
 {
-	if (!run_from.empty() && run_from == run_to) {
-		active = (label == run_from);
-	} else {
-		if (label == run_from)
-			active = true;
-		if (label == run_to)
-			active = false;
-	}
-	return active;
-}
+	SynthPass() : ScriptPass("synth", "generic synthesis script") { }
 
-struct SynthPass : public Pass {
-	SynthPass() : Pass("synth", "generic synthesis script") { }
-	virtual void help()
+	virtual void help() YS_OVERRIDE
 	{
 		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
 		log("\n");
@@ -75,49 +64,28 @@ struct SynthPass : public Pass {
 		log("\n");
 		log("\n");
 		log("The following commands are executed by this synthesis command:\n");
+		help_script();
 		log("\n");
-		log("    begin:\n");
-		log("        hierarchy -check [-top <top>]\n");
-		log("\n");
-		log("    coarse:\n");
-		log("        proc\n");
-		log("        opt_const\n");
-		log("        opt_clean\n");
-		log("        check\n");
-		log("        opt\n");
-		log("        wreduce\n");
-		log("        alumacc\n");
-		log("        share\n");
-		log("        opt\n");
-		log("        fsm\n");
-		log("        opt -fast\n");
-		log("        memory -nomap\n");
-		log("        opt_clean\n");
-		log("\n");
-		log("    fine:\n");
-		log("        opt -fast -full\n");
-		log("        memory_map\n");
-		log("        opt -full\n");
-		log("        techmap\n");
-		log("        opt -fast\n");
-	#ifdef YOSYS_ENABLE_ABC
-		log("        abc -fast\n");
-		log("        opt -fast\n");
-	#endif
-		log("\n");
-		log("    check:\n");
-		log("        hierarchy -check\n");
-		log("        stat\n");
-		log("        check\n");
-		log("\n");
 	}
-	virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
+
+	std::string top_module, fsm_opts, memory_opts;
+	bool noalumacc, nofsm, noabc;
+
+	virtual void clear_flags() YS_OVERRIDE
+	{
+		top_module.clear();
+		fsm_opts.clear();
+		memory_opts.clear();
+
+		noalumacc = false;
+		nofsm = false;
+		noabc = false;
+	}
+
+	virtual void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
 	{
-		std::string top_module, fsm_opts, memory_opts;
-		std::string run_from, run_to;
-		bool noalumacc = false;
-		bool nofsm = false;
-		bool noabc = false;
+		string run_from, run_to;
+		clear_flags();
 
 		size_t argidx;
 		for (argidx = 1; argidx < args.size(); argidx++)
@@ -164,62 +132,69 @@ struct SynthPass : public Pass {
 		if (!design->full_selection())
 			log_cmd_error("This comannd only operates on fully selected designs!\n");
 
-		bool active = run_from.empty();
-
 		log_header("Executing SYNTH pass.\n");
 		log_push();
 
-		if (check_label(active, run_from, run_to, "begin"))
+		run_script(design, run_from, run_to);
+
+		log_pop();
+	}
+
+	virtual void script() YS_OVERRIDE
+	{
+		if (check_label("begin"))
 		{
-			if (top_module.empty())
-				Pass::call(design, stringf("hierarchy -check"));
-			else
-				Pass::call(design, stringf("hierarchy -check -top %s", top_module.c_str()));
+			if (help_mode) {
+				run("hierarchy -check [-top <top>]");
+			} else {
+				if (top_module.empty())
+					run(stringf("hierarchy -check"));
+				else
+					run(stringf("hierarchy -check -top %s", top_module.c_str()));
+			}
 		}
 
-		if (check_label(active, run_from, run_to, "coarse"))
+		if (check_label("coarse"))
 		{
-			Pass::call(design, "proc");
-			Pass::call(design, "opt_const");
-			Pass::call(design, "opt_clean");
-			Pass::call(design, "check");
-			Pass::call(design, "opt");
-			Pass::call(design, "wreduce");
+			run("proc");
+			run("opt_expr");
+			run("opt_clean");
+			run("check");
+			run("opt");
+			run("wreduce");
 			if (!noalumacc)
-				Pass::call(design, "alumacc");
-			Pass::call(design, "share");
-			Pass::call(design, "opt");
+				run("alumacc");
+			run("share");
+			run("opt");
 			if (!nofsm)
-				Pass::call(design, "fsm" + fsm_opts);
-			Pass::call(design, "opt -fast");
-			Pass::call(design, "memory -nomap" + memory_opts);
-			Pass::call(design, "opt_clean");
+				run("fsm" + fsm_opts);
+			run("opt -fast");
+			run("memory -nomap" + memory_opts);
+			run("opt_clean");
 		}
 
-		if (check_label(active, run_from, run_to, "fine"))
+		if (check_label("fine"))
 		{
-			Pass::call(design, "opt -fast -full");
-			Pass::call(design, "memory_map");
-			Pass::call(design, "opt -full");
-			Pass::call(design, "techmap");
-			Pass::call(design, "opt -fast");
+			run("opt -fast -full");
+			run("memory_map");
+			run("opt -full");
+			run("techmap");
+			run("opt -fast");
 
 			if (!noabc) {
 		#ifdef YOSYS_ENABLE_ABC
-				Pass::call(design, "abc -fast");
-				Pass::call(design, "opt -fast");
+				run("abc -fast");
+				run("opt -fast");
 		#endif
 			}
 		}
 
-		if (check_label(active, run_from, run_to, "check"))
+		if (check_label("check"))
 		{
-			Pass::call(design, "hierarchy -check");
-			Pass::call(design, "stat");
-			Pass::call(design, "check");
+			run("hierarchy -check");
+			run("stat");
+			run("check");
 		}
-
-		log_pop();
 	}
 } SynthPass;
 
diff --git a/techlibs/common/techmap.v b/techlibs/common/techmap.v
index ae08c3d17..a623bb516 100644
--- a/techlibs/common/techmap.v
+++ b/techlibs/common/techmap.v
@@ -93,7 +93,7 @@ module _90_shift_ops_shr_shl_sshl_sshr (A, B, Y);
 	localparam BB_WIDTH = `MIN($clog2(shift_left ? Y_WIDTH : A_SIGNED ? WIDTH : A_WIDTH) + 1, B_WIDTH);
 
 	wire [1023:0] _TECHMAP_DO_00_ = "proc;;";
-	wire [1023:0] _TECHMAP_DO_01_ = "RECURSION; CONSTMAP; opt_muxtree; opt_const -mux_undef -mux_bool -fine;;;";
+	wire [1023:0] _TECHMAP_DO_01_ = "RECURSION; CONSTMAP; opt_muxtree; opt_expr -mux_undef -mux_bool -fine;;;";
 
 	integer i;
 	reg [WIDTH-1:0] buffer;
@@ -136,7 +136,7 @@ module _90_shift_shiftx (A, B, Y);
 	localparam extbit = _TECHMAP_CELLTYPE_ == "$shift" ? 1'b0 : 1'bx;
 
 	wire [1023:0] _TECHMAP_DO_00_ = "proc;;";
-	wire [1023:0] _TECHMAP_DO_01_ = "CONSTMAP; opt_muxtree; opt_const -mux_undef -mux_bool -fine;;;";
+	wire [1023:0] _TECHMAP_DO_01_ = "CONSTMAP; opt_muxtree; opt_expr -mux_undef -mux_bool -fine;;;";
 
 	integer i;
 	reg [WIDTH-1:0] buffer;
diff --git a/techlibs/ice40/ice40_opt.cc b/techlibs/ice40/ice40_opt.cc
index 677ac8d77..5730847ce 100644
--- a/techlibs/ice40/ice40_opt.cc
+++ b/techlibs/ice40/ice40_opt.cc
@@ -127,8 +127,8 @@ struct Ice40OptPass : public Pass {
 		log("\n");
 		log("    do\n");
 		log("        <ice40 specific optimizations>\n");
-		log("        opt_const -mux_undef -undriven [-full]\n");
-		log("        opt_share\n");
+		log("        opt_expr -mux_undef -undriven [-full]\n");
+		log("        opt_merge\n");
 		log("        opt_rmdff\n");
 		log("        opt_clean\n");
 		log("    while <changed design>\n");
@@ -136,14 +136,14 @@ struct Ice40OptPass : public Pass {
 	}
 	virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
 	{
-		string opt_const_args = "-mux_undef -undriven";
+		string opt_expr_args = "-mux_undef -undriven";
 		log_header("Executing ICE40_OPT pass (performing simple optimizations).\n");
 		log_push();
 
 		size_t argidx;
 		for (argidx = 1; argidx < args.size(); argidx++) {
 			if (args[argidx] == "-full") {
-				opt_const_args += " -full";
+				opt_expr_args += " -full";
 				continue;
 			}
 			break;
@@ -158,8 +158,8 @@ struct Ice40OptPass : public Pass {
 			for (auto module : design->selected_modules())
 				run_ice40_opts(module);
 
-			Pass::call(design, "opt_const " + opt_const_args);
-			Pass::call(design, "opt_share");
+			Pass::call(design, "opt_expr " + opt_expr_args);
+			Pass::call(design, "opt_merge");
 			Pass::call(design, "opt_rmdff");
 			Pass::call(design, "opt_clean");
 
diff --git a/techlibs/ice40/synth_ice40.cc b/techlibs/ice40/synth_ice40.cc
index 92d53f4ab..2ed7642ae 100644
--- a/techlibs/ice40/synth_ice40.cc
+++ b/techlibs/ice40/synth_ice40.cc
@@ -25,18 +25,11 @@
 USING_YOSYS_NAMESPACE
 PRIVATE_NAMESPACE_BEGIN
 
-bool check_label(bool &active, std::string run_from, std::string run_to, std::string label)
+struct SynthIce40Pass : public ScriptPass
 {
-	if (label == run_from)
-		active = true;
-	if (label == run_to)
-		active = false;
-	return active;
-}
+	SynthIce40Pass() : ScriptPass("synth_ice40", "synthesis for iCE40 FPGAs") { }
 
-struct SynthIce40Pass : public Pass {
-	SynthIce40Pass() : Pass("synth_ice40", "synthesis for iCE40 FPGAs") { }
-	virtual void help()
+	virtual void help() YS_OVERRIDE
 	{
 		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
 		log("\n");
@@ -77,73 +70,30 @@ struct SynthIce40Pass : public Pass {
 		log("\n");
 		log("\n");
 		log("The following commands are executed by this synthesis command:\n");
+		help_script();
 		log("\n");
-		log("    begin:\n");
-		log("        read_verilog -lib +/ice40/cells_sim.v\n");
-		log("        hierarchy -check -top <top>\n");
-		log("\n");
-		log("    flatten:         (unless -noflatten)\n");
-		log("        proc\n");
-		log("        flatten\n");
-		log("        tribuf -logic\n");
-		log("\n");
-		log("    coarse:\n");
-		log("        synth -run coarse\n");
-		log("\n");
-		log("    bram:            (skip if -nobram)\n");
-		log("        memory_bram -rules +/ice40/brams.txt\n");
-		log("        techmap -map +/ice40/brams_map.v\n");
-		log("\n");
-		log("    fine:\n");
-		log("        opt -fast -mux_undef -undriven -fine\n");
-		log("        memory_map\n");
-		log("        opt -undriven -fine\n");
-		log("        techmap -map +/techmap.v [-map +/ice40/arith_map.v]\n");
-		log("        abc -dff     (only if -retime)\n");
-		log("        ice40_opt\n");
-		log("\n");
-		log("    map_ffs:\n");
-		log("        dffsr2dff\n");
-		log("        dff2dffe -direct-match $_DFF_*\n");
-		log("        techmap -map +/ice40/cells_map.v\n");
-		log("        opt_const -mux_undef\n");
-		log("        simplemap\n");
-		log("        ice40_ffinit\n");
-		log("        ice40_ffssr\n");
-		log("        ice40_opt -full\n");
-		log("\n");
-		log("    map_luts:\n");
-		log("        abc          (only if -abc2)\n");
-		log("        ice40_opt    (only if -abc2)\n");
-		log("        abc -lut 4\n");
-		log("        clean\n");
-		log("\n");
-		log("    map_cells:\n");
-		log("        techmap -map +/ice40/cells_map.v\n");
-		log("        clean\n");
-		log("\n");
-		log("    check:\n");
-		log("        hierarchy -check\n");
-		log("        stat\n");
-		log("        check -noinit\n");
-		log("\n");
-		log("    blif:\n");
-		log("        write_blif -gates -attr -param <file-name>\n");
-		log("\n");
-		log("    edif:\n");
-		log("        write_edif <file-name>\n");
-		log("\n");
 	}
-	virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
+
+	string top_opt = "-auto-top";
+	string blif_file, edif_file;
+	bool nocarry, nobram, flatten, retime, abc2;
+
+	virtual void clear_flags() YS_OVERRIDE
+	{
+		top_opt = "-auto-top";
+		blif_file = "";
+		edif_file = "";
+		nocarry = false;
+		nobram = false;
+		flatten = true;
+		retime = false;
+		abc2 = false;
+	}
+
+	virtual void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
 	{
-		std::string top_opt = "-auto-top";
 		std::string run_from, run_to;
-		std::string blif_file, edif_file;
-		bool nocarry = false;
-		bool nobram = false;
-		bool flatten = true;
-		bool retime = false;
-		bool abc2 = false;
+		clear_flags();
 
 		size_t argidx;
 		for (argidx = 1; argidx < args.size(); argidx++)
@@ -199,97 +149,100 @@ struct SynthIce40Pass : public Pass {
 		if (!design->full_selection())
 			log_cmd_error("This comannd only operates on fully selected designs!\n");
 
-		bool active = run_from.empty();
-
 		log_header("Executing SYNTH_ICE40 pass.\n");
 		log_push();
 
-		if (check_label(active, run_from, run_to, "begin"))
+		run_script(design, run_from, run_to);
+
+		log_pop();
+	}
+
+	virtual void script() YS_OVERRIDE
+	{
+		if (check_label("begin"))
 		{
-			Pass::call(design, "read_verilog -lib +/ice40/cells_sim.v");
-			Pass::call(design, stringf("hierarchy -check %s", top_opt.c_str()));
+			run("read_verilog -lib +/ice40/cells_sim.v");
+			run(stringf("hierarchy -check %s", help_mode ? "-top <top>" : top_opt.c_str()));
 		}
 
-		if (flatten && check_label(active, run_from, run_to, "flatten"))
+		if (flatten && check_label("flatten", "(unless -noflatten)"))
 		{
-			Pass::call(design, "proc");
-			Pass::call(design, "flatten");
-			Pass::call(design, "tribuf -logic");
+			run("proc");
+			run("flatten");
+			run("tribuf -logic");
 		}
 
-		if (check_label(active, run_from, run_to, "coarse"))
+		if (check_label("coarse"))
 		{
-			Pass::call(design, "synth -run coarse");
+			run("synth -run coarse");
 		}
 
-		if (!nobram && check_label(active, run_from, run_to, "bram"))
+		if (!nobram && check_label("bram", "(skip if -nobram)"))
 		{
-			Pass::call(design, "memory_bram -rules +/ice40/brams.txt");
-			Pass::call(design, "techmap -map +/ice40/brams_map.v");
+			run("memory_bram -rules +/ice40/brams.txt");
+			run("techmap -map +/ice40/brams_map.v");
 		}
 
-		if (check_label(active, run_from, run_to, "fine"))
+		if (check_label("fine"))
 		{
-			Pass::call(design, "opt -fast -mux_undef -undriven -fine");
-			Pass::call(design, "memory_map");
-			Pass::call(design, "opt -undriven -fine");
+			run("opt -fast -mux_undef -undriven -fine");
+			run("memory_map");
+			run("opt -undriven -fine");
 			if (nocarry)
-				Pass::call(design, "techmap");
+				run("techmap");
 			else
-				Pass::call(design, "techmap -map +/techmap.v -map +/ice40/arith_map.v");
-			if (retime)
-				Pass::call(design, "abc -dff");
-			Pass::call(design, "ice40_opt");
+				run("techmap -map +/techmap.v -map +/ice40/arith_map.v");
+			if (retime || help_mode)
+				run("abc -dff", "(only if -retime)");
+			run("ice40_opt");
 		}
 
-		if (check_label(active, run_from, run_to, "map_ffs"))
+		if (check_label("map_ffs"))
 		{
-			Pass::call(design, "dffsr2dff");
-			Pass::call(design, "dff2dffe -direct-match $_DFF_*");
-			Pass::call(design, "techmap -map +/ice40/cells_map.v");
-			Pass::call(design, "opt_const -mux_undef");
-			Pass::call(design, "simplemap");
-			Pass::call(design, "ice40_ffinit");
-			Pass::call(design, "ice40_ffssr");
-			Pass::call(design, "ice40_opt -full");
+			run("dffsr2dff");
+			run("dff2dffe -direct-match $_DFF_*");
+			run("techmap -map +/ice40/cells_map.v");
+			run("opt_expr -mux_undef");
+			run("simplemap");
+			run("ice40_ffinit");
+			run("ice40_ffssr");
+			run("ice40_opt -full");
 		}
 
-		if (check_label(active, run_from, run_to, "map_luts"))
+		if (check_label("map_luts"))
 		{
-			if (abc2) {
-				Pass::call(design, "abc");
-				Pass::call(design, "ice40_opt");
+			if (abc2 || help_mode) {
+				run("abc", "      (only if -abc2)");
+				run("ice40_opt", "(only if -abc2)");
 			}
-			Pass::call(design, "abc -lut 4");
-			Pass::call(design, "clean");
+			run("abc -lut 4");
+			run("clean");
 		}
 
-		if (check_label(active, run_from, run_to, "map_cells"))
+		if (check_label("map_cells"))
 		{
-			Pass::call(design, "techmap -map +/ice40/cells_map.v");
-			Pass::call(design, "clean");
+			run("techmap -map +/ice40/cells_map.v");
+			run("clean");
 		}
 
-		if (check_label(active, run_from, run_to, "check"))
+		if (check_label("check"))
 		{
-			Pass::call(design, "hierarchy -check");
-			Pass::call(design, "stat");
-			Pass::call(design, "check -noinit");
+			run("hierarchy -check");
+			run("stat");
+			run("check -noinit");
 		}
 
-		if (check_label(active, run_from, run_to, "blif"))
+		if (check_label("blif"))
 		{
-			if (!blif_file.empty())
-				Pass::call(design, stringf("write_blif -gates -attr -param %s", blif_file.c_str()));
+			if (!blif_file.empty() || help_mode)
+				run(stringf("write_blif -gates -attr -param %s", help_mode ? "<file-name>" : blif_file.c_str()));
 		}
 
-		if (check_label(active, run_from, run_to, "edif"))
+		if (check_label("edif"))
 		{
-			if (!edif_file.empty())
-				Pass::call(design, stringf("write_edif %s", edif_file.c_str()));
+			if (!edif_file.empty() || help_mode)
+				run(stringf("write_edif %s", help_mode ? "<file-name>" : edif_file.c_str()));
 		}
-
-		log_pop();
 	}
 } SynthIce40Pass;