Added support for truncating of wires to wreduce pass

kernel/modtools.h

@@ -59,14 +59,20 @@ struct ModIndex : public RTLIL::Monitor
 
 	void port_add(RTLIL::Cell *cell, RTLIL::IdString port, const RTLIL::SigSpec &sig)
 	{
-		for (int i = 0; i < SIZE(sig); i++)
+		for (int i = 0; i < SIZE(sig); i++) {
-			database[sigmap(sig[i])].ports.insert(PortInfo(cell, port, i));
+			RTLIL::SigBit bit = sigmap(sig[i]);
+			if (bit.wire)
+				database[bit].ports.insert(PortInfo(cell, port, i));
+		}
 	}
 
 	void port_del(RTLIL::Cell *cell, RTLIL::IdString port, const RTLIL::SigSpec &sig)
 	{
-		for (int i = 0; i < SIZE(sig); i++)
+		for (int i = 0; i < SIZE(sig); i++) {
-			database[sigmap(sig[i])].ports.erase(PortInfo(cell, port, i));
+			RTLIL::SigBit bit = sigmap(sig[i]);
+			if (bit.wire)
+				database[bit].ports.erase(PortInfo(cell, port, i));
+		}
 	}
 
 	const SigBitInfo &info(RTLIL::SigBit bit)
@@ -83,10 +89,11 @@ struct ModIndex : public RTLIL::Monitor
 		for (auto wire : module->wires())
 			if (wire->port_input || wire->port_output)
 				for (int i = 0; i < SIZE(wire); i++) {
-					if (wire->port_input)
+					RTLIL::SigBit bit = sigmap(RTLIL::SigBit(wire, i));
-						database[sigmap(RTLIL::SigBit(wire, i))].is_input = true;
+					if (bit.wire && wire->port_input)
-					if (wire->port_output)
+						database[bit].is_input = true;
-						database[sigmap(RTLIL::SigBit(wire, i))].is_output = true;
+					if (bit.wire && wire->port_output)
+						database[bit].is_output = true;
 				}
 		for (auto cell : module->cells())
 			for (auto &conn : cell->connections())
@@ -137,6 +144,7 @@ struct ModIndex : public RTLIL::Monitor
 	{
 		if (auto_reload_module)
 			reload_module();
+
 		auto it = database.find(sigmap(bit));
 		if (it == database.end())
 			return nullptr;

kernel/rtlil.cc

@@ -1071,6 +1071,36 @@ void RTLIL::Module::rename(RTLIL::IdString old_name, RTLIL::IdString new_name)
 		log_abort();
 }
 
+void RTLIL::Module::swap_names(RTLIL::Wire *w1, RTLIL::Wire *w2)
+{
+	log_assert(wires_[w1->name] == w1);
+	log_assert(wires_[w2->name] == w2);
+	log_assert(refcount_wires_ == 0);
+
+	wires_.erase(w1->name);
+	wires_.erase(w2->name);
+
+	std::swap(w1->name, w2->name);
+
+	wires_[w1->name] = w1;
+	wires_[w2->name] = w2;
+}
+
+void RTLIL::Module::swap_names(RTLIL::Cell *c1, RTLIL::Cell *c2)
+{
+	log_assert(cells_[c1->name] == c1);
+	log_assert(cells_[c2->name] == c2);
+	log_assert(refcount_cells_ == 0);
+
+	cells_.erase(c1->name);
+	cells_.erase(c2->name);
+
+	std::swap(c1->name, c2->name);
+
+	cells_[c1->name] = c1;
+	cells_[c2->name] = c2;
+}
+
 static bool fixup_ports_compare(const RTLIL::Wire *a, const RTLIL::Wire *b)
 {
 	if (a->port_id && !b->port_id)

kernel/rtlil.h

@@ -590,6 +590,10 @@ public:
 	std::vector<RTLIL::Wire*> selected_wires() const;
 	std::vector<RTLIL::Cell*> selected_cells() const;
 
+	template<typename T> bool selected(T *member) const {
+		return design->selected_member(name, member->name);
+	}
+
 	RTLIL::Wire* wire(RTLIL::IdString id) { return wires_.count(id) ? wires_.at(id) : nullptr; }
 	RTLIL::Cell* cell(RTLIL::IdString id) { return cells_.count(id) ? cells_.at(id) : nullptr; }
 
@@ -604,6 +608,9 @@ public:
 	void rename(RTLIL::Cell *cell, RTLIL::IdString new_name);
 	void rename(RTLIL::IdString old_name, RTLIL::IdString new_name);
 
+	void swap_names(RTLIL::Wire *w1, RTLIL::Wire *w2);
+	void swap_names(RTLIL::Cell *c1, RTLIL::Cell *c2);
+
 	RTLIL::Wire *addWire(RTLIL::IdString name, int width = 1);
 	RTLIL::Wire *addWire(RTLIL::IdString name, const RTLIL::Wire *other);
 

passes/cmds/wreduce.cc

@@ -21,8 +21,6 @@
 #include "kernel/sigtools.h"
 #include "kernel/modtools.h"
 
-#include <type_traits>
-
 USING_YOSYS_NAMESPACE
 using namespace RTLIL;
 
@@ -243,6 +241,14 @@ struct WreduceWorker
 		return did_something;
 	}
 
+	static int count_nontrivial_wire_attrs(RTLIL::Wire *w)
+	{
+		int count = w->attributes.size();
+		count -= w->attributes.count("\\src");
+		count -= w->attributes.count("\\unused_bits");
+		return count;
+	}
+
 	void run()
 	{
 		for (auto c : module->selected_cells())
@@ -257,7 +263,32 @@ struct WreduceWorker
 			work_queue_cells.clear();
 			for (auto bit : work_queue_bits)
 			for (auto port : mi.query_ports(bit))
-				work_queue_cells.insert(port.cell);
+				if (module->selected(port.cell))
+					work_queue_cells.insert(port.cell);
+		}
+
+		for (auto w : module->selected_wires())
+		{
+			int unused_top_bits = 0;
+
+			if (w->port_id > 0 || count_nontrivial_wire_attrs(w) > 0)
+				continue;
+
+			for (int i = SIZE(w)-1; i >= 0; i--) {
+				SigBit bit(w, i);
+				auto info = mi.query(bit);
+				if (info && (info->is_input || info->is_output || SIZE(info->ports) > 0))
+					break;
+				unused_top_bits++;
+			}
+
+			if (0 < unused_top_bits && unused_top_bits < SIZE(w)) {
+				log("Removed top %d bits (of %d) from wire %s.%s.\n", unused_top_bits, SIZE(w), log_id(module), log_id(w));
+				Wire *nw = module->addWire(NEW_ID, w);
+				nw->width = SIZE(w) - unused_top_bits;
+				module->connect(nw, SigSpec(w).extract(0, SIZE(nw)));
+				module->swap_names(w, nw);
+			}
 		}
 	}
 };
@@ -270,7 +301,12 @@ struct WreducePass : public Pass {
 		log("\n");
 		log("    wreduce [options] [selection]\n");
 		log("\n");
-		log("This command reduces the word size of operations.\n");
+		log("This command reduces the word size of operations. For example it will replace\n");
+		log("the 32 bit adders in the following code with adders of more appropriate widths:\n");
+		log("\n");
+		log("    module test(input [3:0] a, b, c, output [7:0] y);\n");
+		log("        assign y = a + b + c + 1;\n");
+		log("    endmodule\n");
 		log("\n");
 	}
 	virtual void execute(std::vector<std::string> args, Design *design)