Add abc9_ops -prep_holes
authorEddie Hung <eddie@fpgeh.com>
Tue, 31 Dec 2019 02:00:49 +0000 (18:00 -0800)
committerEddie Hung <eddie@fpgeh.com>
Tue, 31 Dec 2019 02:00:49 +0000 (18:00 -0800)
backends/aiger/xaiger.cc
passes/techmap/abc9.cc
passes/techmap/abc9_ops.cc

index e7d767721387f9782c7da6d904ee9a3b35ff7766..73af3bdfb2de2d1cf1b4593b736ac34df79407b6 100644 (file)
@@ -680,12 +680,11 @@ struct XAigerWriter
                //      write_o_buffer(0);
 
                if (!box_list.empty() || !ff_bits.empty()) {
-                       RTLIL::Module *holes_module = module->design->addModule("$__holes__");
+                       RTLIL::Module *holes_module = module->design->module(stringf("%s$holes", module->name.c_str()));
                        log_assert(holes_module);
 
                        dict<IdString, Cell*> cell_cache;
 
-                       int port_id = 1;
                        int box_count = 0;
                        for (auto cell : box_list) {
                                RTLIL::Module* orig_box_module = module->design->module(cell->type);
@@ -696,85 +695,21 @@ struct XAigerWriter
                                        Pass::call_on_module(module->design, box_module, "proc");
 
                                int box_inputs = 0, box_outputs = 0;
-                               auto r = cell_cache.insert(std::make_pair(derived_name, nullptr));
-                               Cell *holes_cell = r.first->second;
-                               if (r.second && box_module->get_bool_attribute("\\whitebox")) {
-                                       holes_cell = holes_module->addCell(cell->name, cell->type);
-                                       holes_cell->parameters = cell->parameters;
-                                       r.first->second = holes_cell;
-
-                                       // Since Module::derive() will create a new module, there
-                                       //   is a chance that the ports will be alphabetically ordered
-                                       //   again, which is a problem when carry-chains are involved.
-                                       //   Inherit the port ordering from the original module here...
-                                       //   (and set the port_id below, when iterating through those)
-                                       log_assert(GetSize(box_module->ports) == GetSize(orig_box_module->ports));
-                                       box_module->ports = orig_box_module->ports;
-                               }
-
                                // NB: Assume box_module->ports are sorted alphabetically
                                //     (as RTLIL::Module::fixup_ports() would do)
-                               int box_port_id = 1;
                                for (const auto &port_name : box_module->ports) {
                                        RTLIL::Wire *w = box_module->wire(port_name);
                                        log_assert(w);
-                                       if (r.second)
-                                               w->port_id = box_port_id++;
-                                       RTLIL::Wire *holes_wire;
-                                       RTLIL::SigSpec port_sig;
                                        if (w->port_input)
-                                               for (int i = 0; i < GetSize(w); i++) {
-                                                       box_inputs++;
-                                                       holes_wire = holes_module->wire(stringf("\\i%d", box_inputs));
-                                                       if (!holes_wire) {
-                                                               holes_wire = holes_module->addWire(stringf("\\i%d", box_inputs));
-                                                               holes_wire->port_input = true;
-                                                               holes_wire->port_id = port_id++;
-                                                               holes_module->ports.push_back(holes_wire->name);
-                                                       }
-                                                       if (holes_cell)
-                                                               port_sig.append(holes_wire);
-                                               }
-                                       if (w->port_output) {
+                                               box_inputs += GetSize(w);
+                                       if (w->port_output)
                                                box_outputs += GetSize(w);
-                                               for (int i = 0; i < GetSize(w); i++) {
-                                                       if (GetSize(w) == 1)
-                                                               holes_wire = holes_module->addWire(stringf("$abc%s.%s", cell->name.c_str(), log_id(w->name)));
-                                                       else
-                                                               holes_wire = holes_module->addWire(stringf("$abc%s.%s[%d]", cell->name.c_str(), log_id(w->name), i));
-                                                       holes_wire->port_output = true;
-                                                       holes_wire->port_id = port_id++;
-                                                       holes_module->ports.push_back(holes_wire->name);
-                                                       if (holes_cell)
-                                                               port_sig.append(holes_wire);
-                                                       else
-                                                               holes_module->connect(holes_wire, State::S0);
-                                               }
-                                       }
-                                       if (!port_sig.empty()) {
-                                               if (r.second)
-                                                       holes_cell->setPort(w->name, port_sig);
-                                               else
-                                                       holes_module->connect(holes_cell->getPort(w->name), port_sig);
-                                       }
                                }
 
                                // For flops only, create an extra 1-bit input that drives a new wire
                                //   called "<cell>.$abc9_currQ" that is used below
-                               if (box_module->get_bool_attribute("\\abc9_flop")) {
-                                       log_assert(holes_cell);
-
+                               if (box_module->get_bool_attribute("\\abc9_flop"))
                                        box_inputs++;
-                                       Wire *holes_wire = holes_module->wire(stringf("\\i%d", box_inputs));
-                                       if (!holes_wire) {
-                                               holes_wire = holes_module->addWire(stringf("\\i%d", box_inputs));
-                                               holes_wire->port_input = true;
-                                               holes_wire->port_id = port_id++;
-                                               holes_module->ports.push_back(holes_wire->name);
-                                       }
-                                       Wire *w = holes_module->addWire(stringf("%s.$abc9_currQ", cell->name.c_str()));
-                                       holes_module->connect(w, holes_wire);
-                               }
 
                                write_h_buffer(box_inputs);
                                write_h_buffer(box_outputs);
@@ -815,79 +750,20 @@ struct XAigerWriter
                        f.write(buffer_str.data(), buffer_str.size());
 
                        if (holes_module) {
-                               log_push();
-
-                               // NB: fixup_ports() will sort ports by name
-                               //holes_module->fixup_ports();
-                               holes_module->check();
-
-                               // Cannot techmap/aigmap/check all lib_whitebox-es outside of write_xaiger
-                               //   since boxes may contain parameters in which case `flatten` would have
-                               //   created a new $paramod ...
-                               Pass::call_on_module(holes_module->design, holes_module, "flatten -wb; techmap; aigmap");
-
-                               dict<SigSig, SigSig> replace;
-                               for (auto it = holes_module->cells_.begin(); it != holes_module->cells_.end(); ) {
-                                       auto cell = it->second;
-                                       if (cell->type.in("$_DFF_N_", "$_DFF_NN0_", "$_DFF_NN1_", "$_DFF_NP0_", "$_DFF_NP1_",
-                                                               "$_DFF_P_", "$_DFF_PN0_", "$_DFF_PN1", "$_DFF_PP0_", "$_DFF_PP1_")) {
-                                               SigBit D = cell->getPort("\\D");
-                                               SigBit Q = cell->getPort("\\Q");
-                                               // Remove the DFF cell from what needs to be a combinatorial box
-                                               it = holes_module->cells_.erase(it);
-                                               Wire *port;
-                                               if (GetSize(Q.wire) == 1)
-                                                       port = holes_module->wire(stringf("$abc%s", Q.wire->name.c_str()));
-                                               else
-                                                       port = holes_module->wire(stringf("$abc%s[%d]", Q.wire->name.c_str(), Q.offset));
-                                               log_assert(port);
-                                               // Prepare to replace "assign <port> = DFF.Q;" with "assign <port> = DFF.D;"
-                                               //   in order to extract the combinatorial control logic that feeds the box
-                                               //   (i.e. clock enable, synchronous reset, etc.)
-                                               replace.insert(std::make_pair(SigSig(port,Q), SigSig(port,D)));
-                                               // Since `flatten` above would have created wires named "<cell>.Q",
-                                               //   extract the pre-techmap cell name
-                                               auto pos = Q.wire->name.str().rfind(".");
-                                               log_assert(pos != std::string::npos);
-                                               IdString driver = Q.wire->name.substr(0, pos);
-                                               // And drive the signal that was previously driven by "DFF.Q" (typically
-                                               //   used to implement clock-enable functionality) with the "<cell>.$abc9_currQ"
-                                               //   wire (which itself is driven an input port) we inserted above
-                                               Wire *currQ = holes_module->wire(stringf("%s.$abc9_currQ", driver.c_str()));
-                                               log_assert(currQ);
-                                               holes_module->connect(Q, currQ);
-                                               continue;
-                                       }
-                                       else if (!cell->type.in("$_NOT_", "$_AND_"))
-                                               log_error("Whitebox contents cannot be represented as AIG. Please verify whiteboxes are synthesisable.\n");
-                                       ++it;
-                               }
-
-                               for (auto &conn : holes_module->connections_) {
-                                       auto it = replace.find(conn);
-                                       if (it != replace.end())
-                                               conn = it->second;
-                               }
-
-                               // Move into a new (temporary) design so that "clean" will only
-                               // operate (and run checks on) this one module
-                               RTLIL::Design *holes_design = new RTLIL::Design;
-                               module->design->modules_.erase(holes_module->name);
-                               holes_design->add(holes_module);
-                               Pass::call(holes_design, "opt -purge");
+                               module->design->selection_stack.emplace_back(false);
+                               module->design->selection().select(holes_module);
 
                                std::stringstream a_buffer;
                                XAigerWriter writer(holes_module, true /* holes_mode */);
                                writer.write_aiger(a_buffer, false /*ascii_mode*/);
-                               delete holes_design;
+
+                               module->design->selection_stack.pop_back();
 
                                f << "a";
                                std::string buffer_str = a_buffer.str();
                                int32_t buffer_size_be = to_big_endian(buffer_str.size());
                                f.write(reinterpret_cast<const char*>(&buffer_size_be), sizeof(buffer_size_be));
                                f.write(buffer_str.data(), buffer_str.size());
-
-                               log_pop();
                        }
                }
 
index cd798cfbeb311f0eaea220a960c69b8c9ab986d0..e11b150652e8fdfefe18698d859e6eee864090d6 100644 (file)
@@ -207,7 +207,7 @@ struct Abc9Pass : public ScriptPass
                        tempdir_name = make_temp_dir(tempdir_name);
 
                        run("scc -set_attr abc9_scc_id {}");
-                       run("abc9_ops -break_scc -prep_dff");
+                       run("abc9_ops -break_scc -prep_dff -prep_holes");
                        run("aigmap");
                        run(stringf("write_xaiger -map %s/input.sym %s/input.xaig", tempdir_name.c_str(), tempdir_name.c_str()),
                                        "write_xaiger -map <abc-temp-dir>/input.sym <abc-temp-dir>/input.xaig");
index 3e7e5ec7f7ab35462929df044cffb65864e850d5..8eb935e1f11d6f73396ef6116719ad7071c1bf98 100644 (file)
@@ -20,6 +20,7 @@
 
 #include "kernel/register.h"
 #include "kernel/sigtools.h"
+#include "kernel/utils.h"
 
 USING_YOSYS_NAMESPACE
 PRIVATE_NAMESPACE_BEGIN
@@ -75,7 +76,8 @@ void break_scc(RTLIL::Module *module)
        module->fixup_ports();
 }
 
-void unbreak_scc(RTLIL::Module *module) {
+void unbreak_scc(RTLIL::Module *module)
+{
        // Now 'unexpose' those wires by undoing
        // the expose operation -- remove them from PO/PI
        // and re-connecting them back together
@@ -96,7 +98,8 @@ void unbreak_scc(RTLIL::Module *module) {
        module->fixup_ports();
 }
 
-void prep_dff(RTLIL::Module *module) {
+void prep_dff(RTLIL::Module *module)
+{
        auto design = module->design;
        log_assert(design);
 
@@ -134,6 +137,306 @@ void prep_dff(RTLIL::Module *module) {
        }
 }
 
+void prep_holes(RTLIL::Module *module)
+{
+       auto design = module->design;
+       log_assert(design);
+
+       SigMap sigmap(module);
+
+       // TODO: Speed up toposort -- ultimately we care about
+       //       box ordering, but not individual AIG cells
+       dict<SigBit, pool<IdString>> bit_drivers, bit_users;
+       TopoSort<IdString, RTLIL::sort_by_id_str> toposort;
+       bool abc9_box_seen = false;
+
+       for (auto cell : module->selected_cells()) {
+               if (cell->type == "$_NOT_")
+               {
+                       SigBit A = sigmap(cell->getPort("\\A").as_bit());
+                       SigBit Y = sigmap(cell->getPort("\\Y").as_bit());
+                       toposort.node(cell->name);
+                       bit_users[A].insert(cell->name);
+                       bit_drivers[Y].insert(cell->name);
+                       continue;
+               }
+
+               if (cell->type == "$_AND_")
+               {
+                       SigBit A = sigmap(cell->getPort("\\A").as_bit());
+                       SigBit B = sigmap(cell->getPort("\\B").as_bit());
+                       SigBit Y = sigmap(cell->getPort("\\Y").as_bit());
+                       toposort.node(cell->name);
+                       bit_users[A].insert(cell->name);
+                       bit_users[B].insert(cell->name);
+                       bit_drivers[Y].insert(cell->name);
+                       continue;
+               }
+
+               if (cell->type == "$__ABC9_FF_")
+                       continue;
+
+               RTLIL::Module* inst_module = design->module(cell->type);
+               if (inst_module) {
+                       if (!inst_module->attributes.count("\\abc9_box_id") || cell->get_bool_attribute("\\abc9_keep"))
+                               continue;
+
+                       for (const auto &conn : cell->connections()) {
+                               auto port_wire = inst_module->wire(conn.first);
+                               // Ignore inout for the sake of topographical ordering
+                               if (port_wire->port_input && !port_wire->port_output)
+                                       for (auto bit : sigmap(conn.second))
+                                               bit_users[bit].insert(cell->name);
+                               if (port_wire->port_output)
+                                       for (auto bit : sigmap(conn.second))
+                                               bit_drivers[bit].insert(cell->name);
+                       }
+
+                        abc9_box_seen = true;
+
+                        toposort.node(cell->name);
+               }
+       }
+
+       if (!abc9_box_seen)
+               return;
+
+       for (auto &it : bit_users)
+               if (bit_drivers.count(it.first))
+                       for (auto driver_cell : bit_drivers.at(it.first))
+                       for (auto user_cell : it.second)
+                               toposort.edge(driver_cell, user_cell);
+
+#if 0
+       toposort.analyze_loops = true;
+#endif
+       bool no_loops YS_ATTRIBUTE(unused) = toposort.sort();
+#if 0
+       unsigned i = 0;
+       for (auto &it : toposort.loops) {
+               log("  loop %d\n", i++);
+               for (auto cell_name : it) {
+                       auto cell = module->cell(cell_name);
+                       log_assert(cell);
+                       log("\t%s (%s @ %s)\n", log_id(cell), log_id(cell->type), cell->get_src_attribute().c_str());
+               }
+       }
+#endif
+       log_assert(no_loops);
+
+       vector<Cell*> box_list;
+       for (auto cell_name : toposort.sorted) {
+               RTLIL::Cell *cell = module->cell(cell_name);
+               log_assert(cell);
+
+               RTLIL::Module* box_module = design->module(cell->type);
+               if (!box_module || !box_module->attributes.count("\\abc9_box_id")
+                               || cell->get_bool_attribute("\\abc9_keep"))
+                       continue;
+
+               bool blackbox = box_module->get_blackbox_attribute(true /* ignore_wb */);
+
+               // Fully pad all unused input connections of this box cell with S0
+               // Fully pad all undriven output connections of this box cell with anonymous wires
+               // NB: Assume box_module->ports are sorted alphabetically
+               //     (as RTLIL::Module::fixup_ports() would do)
+               for (const auto &port_name : box_module->ports) {
+                       RTLIL::Wire* w = box_module->wire(port_name);
+                       log_assert(w);
+                       auto it = cell->connections_.find(port_name);
+                       if (w->port_input) {
+                               RTLIL::SigSpec rhs;
+                               if (it != cell->connections_.end()) {
+                                       if (GetSize(it->second) < GetSize(w))
+                                               it->second.append(RTLIL::SigSpec(State::S0, GetSize(w)-GetSize(it->second)));
+                                       rhs = it->second;
+                               }
+                               else {
+                                       rhs = RTLIL::SigSpec(State::S0, GetSize(w));
+                                       cell->setPort(port_name, rhs);
+                               }
+                       }
+                       if (w->port_output) {
+                               RTLIL::SigSpec rhs;
+                               auto it = cell->connections_.find(w->name);
+                               if (it != cell->connections_.end()) {
+                                       if (GetSize(it->second) < GetSize(w))
+                                               it->second.append(module->addWire(NEW_ID, GetSize(w)-GetSize(it->second)));
+                                       rhs = it->second;
+                               }
+                               else {
+                                       Wire *wire = module->addWire(NEW_ID, GetSize(w));
+                                       if (blackbox)
+                                               wire->set_bool_attribute(ID(abc9_padding));
+                                       rhs = wire;
+                                       cell->setPort(port_name, rhs);
+                               }
+                       }
+               }
+
+               box_list.emplace_back(cell);
+       }
+       log_assert(!box_list.empty());
+
+       RTLIL::Module *holes_module = design->addModule(stringf("%s$holes", module->name.c_str()));
+       log_assert(holes_module);
+
+       dict<IdString, Cell*> cell_cache;
+
+       int port_id = 1;
+       for (auto cell : box_list) {
+               RTLIL::Module* orig_box_module = design->module(cell->type);
+               log_assert(orig_box_module);
+               IdString derived_name = orig_box_module->derive(design, cell->parameters);
+               RTLIL::Module* box_module = design->module(derived_name);
+               if (box_module->has_processes())
+                       Pass::call_on_module(design, box_module, "proc");
+
+               int box_inputs = 0;
+               auto r = cell_cache.insert(std::make_pair(derived_name, nullptr));
+               Cell *holes_cell = r.first->second;
+               if (r.second && box_module->get_bool_attribute("\\whitebox")) {
+                       holes_cell = holes_module->addCell(cell->name, cell->type);
+                       holes_cell->parameters = cell->parameters;
+                       r.first->second = holes_cell;
+
+                       // Since Module::derive() will create a new module, there
+                       //   is a chance that the ports will be alphabetically ordered
+                       //   again, which is a problem when carry-chains are involved.
+                       //   Inherit the port ordering from the original module here...
+                       //   (and set the port_id below, when iterating through those)
+                       log_assert(GetSize(box_module->ports) == GetSize(orig_box_module->ports));
+                       box_module->ports = orig_box_module->ports;
+               }
+
+               // NB: Assume box_module->ports are sorted alphabetically
+               //     (as RTLIL::Module::fixup_ports() would do)
+               int box_port_id = 1;
+               for (const auto &port_name : box_module->ports) {
+                       RTLIL::Wire *w = box_module->wire(port_name);
+                       log_assert(w);
+                       if (r.second)
+                               w->port_id = box_port_id++;
+                       RTLIL::Wire *holes_wire;
+                       RTLIL::SigSpec port_sig;
+                       if (w->port_input)
+                               for (int i = 0; i < GetSize(w); i++) {
+                                       box_inputs++;
+                                       holes_wire = holes_module->wire(stringf("\\i%d", box_inputs));
+                                       if (!holes_wire) {
+                                               holes_wire = holes_module->addWire(stringf("\\i%d", box_inputs));
+                                               holes_wire->port_input = true;
+                                               holes_wire->port_id = port_id++;
+                                               holes_module->ports.push_back(holes_wire->name);
+                                       }
+                                       if (holes_cell)
+                                               port_sig.append(holes_wire);
+                               }
+                       if (w->port_output)
+                               for (int i = 0; i < GetSize(w); i++) {
+                                       if (GetSize(w) == 1)
+                                               holes_wire = holes_module->addWire(stringf("$abc%s.%s", cell->name.c_str(), log_id(w->name)));
+                                       else
+                                               holes_wire = holes_module->addWire(stringf("$abc%s.%s[%d]", cell->name.c_str(), log_id(w->name), i));
+                                       holes_wire->port_output = true;
+                                       holes_wire->port_id = port_id++;
+                                       holes_module->ports.push_back(holes_wire->name);
+                                       if (holes_cell)
+                                               port_sig.append(holes_wire);
+                                       else
+                                               holes_module->connect(holes_wire, State::S0);
+                               }
+                       if (!port_sig.empty()) {
+                               if (r.second)
+                                       holes_cell->setPort(w->name, port_sig);
+                               else
+                                       holes_module->connect(holes_cell->getPort(w->name), port_sig);
+                       }
+               }
+
+               // For flops only, create an extra 1-bit input that drives a new wire
+               //   called "<cell>.$abc9_currQ" that is used below
+               if (box_module->get_bool_attribute("\\abc9_flop")) {
+                       log_assert(holes_cell);
+
+                       box_inputs++;
+                       Wire *holes_wire = holes_module->wire(stringf("\\i%d", box_inputs));
+                       if (!holes_wire) {
+                               holes_wire = holes_module->addWire(stringf("\\i%d", box_inputs));
+                               holes_wire->port_input = true;
+                               holes_wire->port_id = port_id++;
+                               holes_module->ports.push_back(holes_wire->name);
+                       }
+                       Wire *w = holes_module->addWire(stringf("%s.$abc9_currQ", cell->name.c_str()));
+                       holes_module->connect(w, holes_wire);
+               }
+       }
+
+       log_push();
+
+       // NB: fixup_ports() will sort ports by name
+       //holes_module->fixup_ports();
+       holes_module->check();
+
+       // Cannot techmap/aigmap/check all lib_whitebox-es outside of write_xaiger
+       //   since boxes may contain parameters in which case `flatten` would have
+       //   created a new $paramod ...
+       Pass::call_on_module(design, holes_module, "flatten -wb; techmap; aigmap");
+
+       dict<SigSig, SigSig> replace;
+       for (auto it = holes_module->cells_.begin(); it != holes_module->cells_.end(); ) {
+               auto cell = it->second;
+               if (cell->type.in("$_DFF_N_", "$_DFF_NN0_", "$_DFF_NN1_", "$_DFF_NP0_", "$_DFF_NP1_",
+                                       "$_DFF_P_", "$_DFF_PN0_", "$_DFF_PN1", "$_DFF_PP0_", "$_DFF_PP1_")) {
+                       SigBit D = cell->getPort("\\D");
+                       SigBit Q = cell->getPort("\\Q");
+                       // Remove the DFF cell from what needs to be a combinatorial box
+                       it = holes_module->cells_.erase(it);
+                       Wire *port;
+                       if (GetSize(Q.wire) == 1)
+                               port = holes_module->wire(stringf("$abc%s", Q.wire->name.c_str()));
+                       else
+                               port = holes_module->wire(stringf("$abc%s[%d]", Q.wire->name.c_str(), Q.offset));
+                       log_assert(port);
+                       // Prepare to replace "assign <port> = DFF.Q;" with "assign <port> = DFF.D;"
+                       //   in order to extract the combinatorial control logic that feeds the box
+                       //   (i.e. clock enable, synchronous reset, etc.)
+                       replace.insert(std::make_pair(SigSig(port,Q), SigSig(port,D)));
+                       // Since `flatten` above would have created wires named "<cell>.Q",
+                       //   extract the pre-techmap cell name
+                       auto pos = Q.wire->name.str().rfind(".");
+                       log_assert(pos != std::string::npos);
+                       IdString driver = Q.wire->name.substr(0, pos);
+                       // And drive the signal that was previously driven by "DFF.Q" (typically
+                       //   used to implement clock-enable functionality) with the "<cell>.$abc9_currQ"
+                       //   wire (which itself is driven an input port) we inserted above
+                       Wire *currQ = holes_module->wire(stringf("%s.$abc9_currQ", driver.c_str()));
+                       log_assert(currQ);
+                       holes_module->connect(Q, currQ);
+                       continue;
+               }
+               else if (!cell->type.in("$_NOT_", "$_AND_"))
+                       log_error("Whitebox contents cannot be represented as AIG. Please verify whiteboxes are synthesisable.\n");
+               ++it;
+       }
+
+       for (auto &conn : holes_module->connections_) {
+               auto it = replace.find(conn);
+               if (it != replace.end())
+                       conn = it->second;
+       }
+
+       // Move into a new (temporary) design so that "clean" will only
+       // operate (and run checks on) this one module
+       RTLIL::Design *holes_design = new RTLIL::Design;
+       holes_design->add(holes_module);
+       Pass::call(holes_design, "opt -purge");
+       holes_design->modules_.erase(holes_module->name);
+       holes_module->design = design;
+
+       log_pop();
+}
+
 struct Abc9PrepPass : public Pass {
        Abc9PrepPass() : Pass("abc9_ops", "helper functions for ABC9") { }
        void help() YS_OVERRIDE
@@ -151,6 +454,7 @@ struct Abc9PrepPass : public Pass {
                bool break_scc_mode = false;
                bool unbreak_scc_mode = false;
                bool prep_dff_mode = false;
+               bool prep_holes_mode = false;
 
                size_t argidx;
                for (argidx = 1; argidx < args.size(); argidx++) {
@@ -167,6 +471,10 @@ struct Abc9PrepPass : public Pass {
                                prep_dff_mode = true;
                                continue;
                        }
+                       if (arg == "-prep_holes") {
+                               prep_holes_mode = true;
+                               continue;
+                       }
                        break;
                }
                extra_args(args, argidx, design);
@@ -178,6 +486,8 @@ struct Abc9PrepPass : public Pass {
                                unbreak_scc(mod);
                        if (prep_dff_mode)
                                prep_dff(mod);
+                       if (prep_holes_mode)
+                               prep_holes(mod);
                }
        }
 } Abc9PrepPass;