5 files changed, 90 insertions, 6 deletions
diff --git a/passes/pmgen/README.md b/passes/pmgen/README.md
index 223b43059..7a46558b1 100644
--- a/passes/pmgen/README.md
+++ b/passes/pmgen/README.md
@@ -83,8 +83,8 @@ They are declared like state variables, just using the `udata` statement:
     udata <int> min_data_width max_data_width
     udata <IdString> data_port_name
 
-They are atomatically initialzed to the default constructed value of their type
-when ther pattern matcher object is constructed.
+They are automatically initialized to the default constructed value of their type
+when the pattern matcher object is constructed.
 
 Embedded C++ code
 -----------------
@@ -158,7 +158,7 @@ Finally, `filter <expression>` narrows down the remaining list of cells. For
 performance reasons `filter` statements should only be used for things that
 can't be done using `select` and `index`.
 
-The `optional` statement marks optional matches. I.e. the matcher will also
+The `optional` statement marks optional matches. That is, the matcher will also
 explore the case where `mul` is set to `nullptr`. Without the `optional`
 statement a match may only be assigned nullptr when one of the `if` expressions
 evaluates to `false`.
diff --git a/passes/proc/proc_rmdead.cc b/passes/proc/proc_rmdead.cc
index 7c334e661..d2f8d9ead 100644
--- a/passes/proc/proc_rmdead.cc
+++ b/passes/proc/proc_rmdead.cc
@@ -34,7 +34,7 @@ void proc_rmdead(RTLIL::SwitchRule *sw, int &counter)
 
 	for (size_t i = 0; i < sw->cases.size(); i++)
 	{
-		bool is_default = GetSize(sw->cases[i]->compare) == 0 && (!pool.empty() || GetSize(sw->signal) == 0);
+		bool is_default = GetSize(sw->cases[i]->compare) == 0 || GetSize(sw->signal) == 0;
 
 		for (size_t j = 0; j < sw->cases[i]->compare.size(); j++) {
 			RTLIL::SigSpec sig = sw->cases[i]->compare[j];
diff --git a/passes/techmap/Makefile.inc b/passes/techmap/Makefile.inc
index c45571b01..ca5818248 100644
--- a/passes/techmap/Makefile.inc
+++ b/passes/techmap/Makefile.inc
@@ -38,6 +38,7 @@ OBJS += passes/techmap/attrmap.o
 OBJS += passes/techmap/zinit.o
 OBJS += passes/techmap/dff2dffs.o
 OBJS += passes/techmap/flowmap.o
+OBJS += passes/techmap/pmux2shiftx.o
 endif
 
 GENFILES += passes/techmap/techmap.inc
diff --git a/passes/techmap/pmux2shiftx.cc b/passes/techmap/pmux2shiftx.cc
new file mode 100644
index 000000000..08cb06d5f
--- /dev/null
+++ b/passes/techmap/pmux2shiftx.cc
@@ -0,0 +1,83 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#include "kernel/yosys.h"
+#include "kernel/sigtools.h"
+
+USING_YOSYS_NAMESPACE
+PRIVATE_NAMESPACE_BEGIN
+
+struct Pmux2ShiftxPass : public Pass {
+	Pmux2ShiftxPass() : Pass("pmux2shiftx", "transform $pmux cells to $shiftx cells") { }
+	void help() YS_OVERRIDE
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    pmux2shiftx [selection]\n");
+		log("\n");
+		log("This pass transforms $pmux cells to $shiftx cells.\n");
+		log("\n");
+	}
+	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
+	{
+		log_header(design, "Executing PMUX2SHIFTX pass.\n");
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++) {
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		for (auto module : design->selected_modules())
+		for (auto cell : module->selected_cells())
+		{
+			if (cell->type != "$pmux")
+				continue;
+
+			// Create a new encoder, out of a $pmux, that takes
+			// the existing pmux's 'S' input and transforms it
+			// back into a binary value
+			RTLIL::SigSpec shiftx_a;
+			RTLIL::SigSpec pmux_s;
+
+			int s_width = cell->getParam("\\S_WIDTH").as_int();
+			if (!cell->getPort("\\A").is_fully_undef()) {
+				++s_width;
+				shiftx_a.append(cell->getPort("\\A"));
+				pmux_s.append(module->Not(NEW_ID, module->ReduceOr(NEW_ID, cell->getPort("\\S"))));
+			}
+			const int width = cell->getParam("\\WIDTH").as_int();
+			const int clog2width = ceil(log2(s_width));
+
+			RTLIL::SigSpec pmux_b;
+			pmux_b.append(RTLIL::Const(0, clog2width));
+			for (int i = s_width-1; i > 0; i--)
+				pmux_b.append(RTLIL::Const(i, clog2width));
+			shiftx_a.append(cell->getPort("\\B"));
+			pmux_s.append(cell->getPort("\\S"));
+
+			RTLIL::SigSpec pmux_y = module->addWire(NEW_ID, clog2width);
+			module->addPmux(NEW_ID, RTLIL::Const(RTLIL::Sx, clog2width), pmux_b, pmux_s, pmux_y);
+			module->addShiftx(NEW_ID, shiftx_a, pmux_y, cell->getPort("\\Y"));
+			module->remove(cell);
+		}
+	}
+} Pmux2ShiftxPass;
+
+PRIVATE_NAMESPACE_END
diff --git a/passes/techmap/pmuxtree.cc b/passes/techmap/pmuxtree.cc
index b7a22dc3b..6a923f481 100644
--- a/passes/techmap/pmuxtree.cc
+++ b/passes/techmap/pmuxtree.cc
@@ -71,9 +71,9 @@ struct PmuxtreePass : public Pass {
 	{
 		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
 		log("\n");
-		log("    pmuxtree [options] [selection]\n");
+		log("    pmuxtree [selection]\n");
 		log("\n");
-		log("This pass transforms $pmux cells to a trees of $mux cells.\n");
+		log("This pass transforms $pmux cells to trees of $mux cells.\n");
 		log("\n");
 	}
 	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE