Added abc -keepff option

diff --git a/passes/abc/abc.cc b/passes/abc/abc.cc
index 4add6452dfd2a9e06f849b2953e5dd2e2b0efc13..bd0d983acddc19bf676bdc38831855199dc3f75d 100644 (file)
--- a/passes/abc/abc.cc
+++ b/passes/abc/abc.cc
@@ -109,7 +109,7 @@ static void mark_port(RTLIL::SigSpec sig)
        }
 }
 
-static void extract_cell(RTLIL::Cell *cell)
+static void extract_cell(RTLIL::Cell *cell, bool keepff)
 {
        if (cell->type == "$_DFF_N_" || cell->type == "$_DFF_P_")
        {
@@ -121,6 +121,11 @@ static void extract_cell(RTLIL::Cell *cell)
                RTLIL::SigSpec sig_d = cell->connections["\\D"];
                RTLIL::SigSpec sig_q = cell->connections["\\Q"];
 
+               if (keepff)
+                       for (auto &c : sig_q.chunks)
+                               if (c.wire != NULL)
+                                       c.wire->attributes["\\keep"] = 1;
+
                assign_map.apply(sig_d);
                assign_map.apply(sig_q);
 
@@ -403,7 +408,7 @@ static std::string fold_abc_cmd(std::string str)
 }
 
 static void abc_module(RTLIL::Design *design, RTLIL::Module *current_module, std::string script_file, std::string exe_file,
-               std::string liberty_file, std::string constr_file, bool cleanup, int lut_mode, bool dff_mode, std::string clk_str)
+               std::string liberty_file, std::string constr_file, bool cleanup, int lut_mode, bool dff_mode, std::string clk_str, bool keepff)
 {
        module = current_module;
        map_autoidx = RTLIL::autoidx++;
@@ -498,7 +503,7 @@ static void abc_module(RTLIL::Design *design, RTLIL::Module *current_module, std
                if (design->selected(current_module, it.second))
                        cells.push_back(it.second);
        for (auto c : cells)
-               extract_cell(c);
+               extract_cell(c, keepff);
 
        for (auto &wire_it : module->wires) {
                if (wire_it.second->port_id > 0 || wire_it.second->get_bool_attribute("\\keep"))
@@ -940,6 +945,10 @@ struct AbcPass : public Pass {
                log("        with -dff, then it falls back to the automatic dection of clock domain\n");
                log("        if the specified clock is not found in a module.)\n");
                log("\n");
+               log("    -keepff\n");
+               log("        set the \"keep\" attribute on flip-flop output wires. (and thus preserve\n");
+               log("        them, for example for equivialence checking.)\n");
+               log("\n");
                log("    -nocleanup\n");
                log("        when this option is used, the temporary files created by this pass\n");
                log("        are not removed. this is useful for debugging.\n");
@@ -960,7 +969,7 @@ struct AbcPass : public Pass {
 
                std::string exe_file = rewrite_yosys_exe("yosys-abc");
                std::string script_file, liberty_file, constr_file, clk_str;
-               bool dff_mode = false, cleanup = true;
+               bool dff_mode = false, keepff = false, cleanup = true;
                int lut_mode = 0;
 
                size_t argidx;
@@ -1001,6 +1010,10 @@ struct AbcPass : public Pass {
                                clk_str = args[++argidx];
                                continue;
                        }
+                       if (arg == "-keepff") {
+                               keepff = true;
+                               continue;
+                       }
                        if (arg == "-nocleanup") {
                                cleanup = false;
                                continue;
@@ -1020,7 +1033,7 @@ struct AbcPass : public Pass {
                                if (mod_it.second->processes.size() > 0)
                                        log("Skipping module %s as it contains processes.\n", mod_it.second->name.c_str());
                                else
-                                       abc_module(design, mod_it.second, script_file, exe_file, liberty_file, constr_file, cleanup, lut_mode, dff_mode, clk_str);
+                                       abc_module(design, mod_it.second, script_file, exe_file, liberty_file, constr_file, cleanup, lut_mode, dff_mode, clk_str, keepff);
                        }
 
                assign_map.clear();