nextpnr/fpga_interchange/arch.cc

/*
 *  nextpnr -- Next Generation Place and Route
 *
 *  Copyright (C) 2018  Claire Xenia Wolf <claire@yosyshq.com>
 *  Copyright (C) 2018-19  gatecat <gatecat@ds0.me>
 *  Copyright (C) 2021  Symbiflow Authors
 *
 *  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 "arch.h"

#include <algorithm>
#include <boost/algorithm/string.hpp>
#include <boost/range/adaptor/reversed.hpp>
#include <boost/uuid/detail/sha1.hpp>
#include <cmath>
#include <cstring>
#include <queue>
#include <set>

#include "constraints.impl.h"
#include "fpga_interchange.h"
#include "log.h"
#include "nextpnr.h"
#include "placer1.h"
#include "placer_heap.h"
#include "router1.h"
#include "router2.h"
#include "timing.h"
#include "util.h"
#include "xdc.h"

// Include tcl.h late because it messed with defines and let them leave the
// scope of the header.
#include <tcl.h>

//#define DEBUG_BINDING
//#define USE_LOOKAHEAD
//#define DEBUG_CELL_PIN_MAPPING

// Define to enable some idempotent sanity checks for some important
// operations prior to placement and routing.
#define IDEMPOTENT_CHECK

NEXTPNR_NAMESPACE_BEGIN
struct SiteBelPair
{
    std::string site;
    IdString bel;

    SiteBelPair() {}
    SiteBelPair(std::string site, IdString bel) : site(site), bel(bel) {}

    bool operator==(const SiteBelPair &other) const { return site == other.site && bel == other.bel; }
    unsigned int hash() const { return mkhash(std::hash<std::string>()(site), bel.hash()); }
};

static std::pair<std::string, std::string> split_identifier_name_dot(const std::string &name)
{
    size_t first_dot = name.find('.');
    NPNR_ASSERT(first_dot != std::string::npos);
    return std::make_pair(name.substr(0, first_dot), name.substr(first_dot + 1));
};

// -----------------------------------------------------------------------

void IdString::initialize_arch(const BaseCtx *ctx) {}

// -----------------------------------------------------------------------

static const ChipInfoPOD *get_chip_info(const RelPtr<ChipInfoPOD> *ptr) { return ptr->get(); }

static std::string sha1_hash(const char *data, size_t size)
{
    boost::uuids::detail::sha1 hasher;
    hasher.process_bytes(data, size);

    // unsigned int[5]
    boost::uuids::detail::sha1::digest_type digest;
    hasher.get_digest(digest);

    std::ostringstream buf;
    for (int i = 0; i < 5; ++i)
        buf << std::hex << std::setfill('0') << std::setw(8) << digest[i];

    return buf.str();
}

Arch::Arch(ArchArgs args) : args(args), disallow_site_routing(false)
{
    try {
        blob_file.open(args.chipdb);
        if (args.chipdb.empty() || !blob_file.is_open())
            log_error("Unable to read chipdb %s\n", args.chipdb.c_str());
        const char *blob = reinterpret_cast<const char *>(blob_file.data());

        chipdb_hash = sha1_hash(blob, blob_file.size());
        chip_info = get_chip_info(reinterpret_cast<const RelPtr<ChipInfoPOD> *>(blob));
    } catch (...) {
        log_error("Unable to read chipdb %s\n", args.chipdb.c_str());
    }

    if (chip_info->version != kExpectedChipInfoVersion) {
        log_error("Expected chipdb with version %d found version %d\n", kExpectedChipInfoVersion, chip_info->version);
    }

    // Read strings from constids into IdString database, checking that list
    // is unique and matches expected constid value.
    const RelSlice<RelPtr<char>> &constids = *chip_info->constids;
    for (size_t i = 0; i < constids.size(); ++i) {
        IdString::initialize_add(this, constids[i].get(), i + 1);
    }

    id_GND = id("GND");
    id_VCC = id("VCC");

    // Sanity check cell name ids.
    const CellMapPOD &cell_map = *chip_info->cell_map;
    int32_t first_cell_id = cell_map.cell_names[0];
    for (int32_t i = 0; i < cell_map.cell_names.ssize(); ++i) {
        log_assert(cell_map.cell_names[i] == i + first_cell_id);
    }

    io_port_types.emplace(this->id("$nextpnr_ibuf"));
    io_port_types.emplace(this->id("$nextpnr_obuf"));
    io_port_types.emplace(this->id("$nextpnr_iobuf"));
    io_port_types.emplace(this->id("$nextpnr_inv"));

    if (!this->args.package.empty()) {
        IdString package = this->id(this->args.package);
        package_index = -1;
        for (size_t i = 0; i < chip_info->packages.size(); ++i) {
            if (IdString(chip_info->packages[i].package) == package) {
                NPNR_ASSERT(package_index == -1);
                package_index = i;
            }
        }

        if (package_index == -1) {
            log_error("Could not find package '%s' in chipdb.\n", this->args.package.c_str());
        }
    } else {
        // Default to first package.
        NPNR_ASSERT(chip_info->packages.size() > 0);
        if (chip_info->packages.size() == 1) {
            IdString package_name(chip_info->packages[0].package);
            this->args.package = package_name.str(this);
            package_index = 0;
        } else {
            log_info(
                    "Package must be specified (with --package arg) when multiple packages are available, packages:\n");
            for (const auto &package : chip_info->packages) {
                log_info(" - %s\n", IdString(package.package).c_str(this));
            }
            log_error("--package is required!\n");
        }
    }

    pool<SiteBelPair> site_bel_pads;
    for (const auto &package_pin : chip_info->packages[package_index].pins) {
        IdString site(package_pin.site);
        IdString bel(package_pin.bel);
        site_bel_pads.emplace(SiteBelPair(site.str(this), bel));
    }

    for (BelId bel : getBels()) {
        auto &bel_data = bel_info(chip_info, bel);
        const SiteInstInfoPOD &site = get_site_inst(bel);
        auto iter = site_bel_pads.find(SiteBelPair(site.site_name.get(), IdString(bel_data.name)));
        if (iter != site_bel_pads.end()) {
            pads.emplace(bel);
        }
    }

    explain_constraints = false;

    int tile_type_index = 0;
    size_t max_tag_count = 0;

    for (const TileTypeInfoPOD &tile_type : chip_info->tile_types) {
        max_tag_count = std::max(max_tag_count, tile_type.tags.size());

        auto &type_definition = constraints.definitions[tile_type_index++];
        for (const ConstraintTagPOD &tag : tile_type.tags) {
            type_definition.emplace_back();
            auto &definition = type_definition.back();
            definition.prefix = IdString(tag.tag_prefix);
            definition.default_state = IdString(tag.default_state);
            NPNR_ASSERT(tag.states.size() < kMaxState);

            definition.states.reserve(tag.states.size());
            for (auto state : tag.states) {
                definition.states.push_back(IdString(state));
            }
        }

        // Logic BELs (e.g. placable BELs) should always appear first in the
        // bel data list.
        //
        // When iterating over BELs this property is depended on to skip
        // non-placable BELs (e.g. routing BELs and site ports).
        bool in_logic_bels = true;
        for (const BelInfoPOD &bel_info : tile_type.bel_data) {
            if (in_logic_bels && bel_info.category != BEL_CATEGORY_LOGIC) {
                in_logic_bels = false;
            }

            if (!in_logic_bels) {
                NPNR_ASSERT(bel_info.category != BEL_CATEGORY_LOGIC);
            }
        }
    }

    // Initially LutElement vectors for each tile type.
    tile_type_index = 0;
    max_lut_cells = 0;
    max_lut_pins = 0;
    lut_elements.resize(chip_info->tile_types.size());
    for (const TileTypeInfoPOD &tile_type : chip_info->tile_types) {
        std::vector<LutElement> &elements = lut_elements[tile_type_index++];
        elements.reserve(tile_type.lut_elements.size());

        int lut_cells_count = 0;
        for (auto &lut_element : tile_type.lut_elements) {
            elements.emplace_back();

            LutElement &element = elements.back();
            element.width = lut_element.width;
            for (auto &lut_bel : lut_element.lut_bels) {
                IdString name(lut_bel.name);
                auto result = element.lut_bels.emplace(name, LutBel());
                NPNR_ASSERT(result.second);
                LutBel &lut = result.first->second;

                lut.name = name;

                lut.low_bit = lut_bel.low_bit;
                lut.high_bit = lut_bel.high_bit;

                lut.pins.reserve(lut_bel.pins.size());
                for (size_t i = 0; i < lut_bel.pins.size(); ++i) {
                    IdString pin(lut_bel.pins[i]);
                    lut.pins.push_back(pin);
                    lut.pin_to_index[pin] = i;
                }

                lut.output_pin = IdString(lut_bel.out_pin);
                lut_cells_count++;

                max_lut_pins = std::max((int)lut_bel.pins.size(), max_lut_pins);
            }

            element.compute_pin_order();
        }

        max_lut_cells = std::max(lut_cells_count, max_lut_cells);
    }

    // Map lut cell types to their LutCellPOD
    wire_lut = nullptr;
    for (const LutCellPOD &lut_cell : chip_info->cell_map->lut_cells) {
        IdString cell_type(lut_cell.cell);
        auto result = lut_cells.emplace(cell_type, &lut_cell);
        NPNR_ASSERT(result.second);

        if (lut_cell.input_pins.size() == 1) {
            // Only really expecting 1 single input LUT type!
            NPNR_ASSERT(wire_lut == nullptr);
            wire_lut = &lut_cell;
        }
    }

    raw_bin_constant = std::regex("[01]+", std::regex_constants::ECMAScript | std::regex_constants::optimize);
    verilog_bin_constant =
            std::regex("([0-9]+)'b([01]+)", std::regex_constants::ECMAScript | std::regex_constants::optimize);
    verilog_hex_constant =
            std::regex("([0-9]+)'h([0-9a-fA-F]+)", std::regex_constants::ECMAScript | std::regex_constants::optimize);

    default_tags.resize(max_tag_count);
}

void Arch::init()
{
#ifdef USE_LOOKAHEAD
    lookahead.init(getCtx(), getCtx());
#endif
    dedicated_interconnect.init(getCtx());
    cell_parameters.init(getCtx());

    for (size_t tile_type = 0; tile_type < chip_info->tile_types.size(); ++tile_type) {
        pseudo_pip_data.init_tile_type(getCtx(), tile_type);
    }

    // Warn if there is no preferred constant net defined in the architecture
    IdString const_net_name(getCtx()->chip_info->constants->best_constant_net);
    if (const_net_name == IdString()) {
        log_warning("The architecture does not specify preferred constant net. Using VCC as default.\n");
    }
}

// -----------------------------------------------------------------------

std::string Arch::getChipName() const { return chip_info->name.get(); }

// -----------------------------------------------------------------------

IdString Arch::archArgsToId(ArchArgs args) const { return IdString(); }

// -----------------------------------------------------------------------

void Arch::setup_byname() const
{
    by_name_mutex.lock();

    if (tile_by_name.empty()) {
        for (int i = 0; i < chip_info->tiles.ssize(); i++) {
            tile_by_name[id(chip_info->tiles[i].name.get())] = i;
        }
    }

    if (site_by_name.empty()) {
        for (int i = 0; i < chip_info->tiles.ssize(); i++) {
            auto &tile = chip_info->tiles[i];
            auto &tile_type = chip_info->tile_types[tile.type];
            for (size_t j = 0; j < tile_type.site_types.size(); j++) {
                auto &site = chip_info->sites[tile.sites[j]];
                site_by_name[id(site.name.get())] = std::make_pair(i, j);
            }
        }
    }

    by_name_mutex.unlock();
}

BelId Arch::getBelByName(IdStringList name) const
{
    BelId ret;
    if (name.ids.size() != 2) {
        return BelId();
    }

    setup_byname();

    int tile, site;
    std::tie(tile, site) = site_by_name.at(name.ids[0]);
    auto &tile_info = chip_info->tile_types[chip_info->tiles[tile].type];
    IdString belname = name.ids[1];
    for (int i = 0; i < tile_info.bel_data.ssize(); i++) {
        if (tile_info.bel_data[i].site == site && tile_info.bel_data[i].name == belname.index) {
            ret.tile = tile;
            ret.index = i;
            break;
        }
    }

    return ret;
}

BelRange Arch::getBelsByTile(int x, int y) const
{
    BelRange br;

    br.b.cursor_tile = get_tile_index(x, y);
    br.e.cursor_tile = br.b.cursor_tile;
    br.b.cursor_index = 0;
    br.e.cursor_index = chip_info->tile_types[chip_info->tiles[br.b.cursor_tile].type].bel_data.size();
    br.b.chip = chip_info;
    br.e.chip = chip_info;

    if (br.b != br.e) {
        ++br.e;
    }
    return br;
}

WireId Arch::getBelPinWire(BelId bel, IdString pin) const
{
    NPNR_ASSERT(bel != BelId());

    int pin_index = get_bel_pin_index(bel, pin);

    auto &bel_data = bel_info(chip_info, bel);
    NPNR_ASSERT(pin_index >= 0 && pin_index < bel_data.num_bel_wires);

    const int32_t *wires = bel_data.wires.get();
    int32_t wire_index = wires[pin_index];
    if (wire_index < 0) {
        // This BEL pin is not connected.
        return WireId();
    } else {
        return canonical_wire(chip_info, bel.tile, wire_index);
    }
}

PortType Arch::getBelPinType(BelId bel, IdString pin) const
{
    NPNR_ASSERT(bel != BelId());

    int pin_index = get_bel_pin_index(bel, pin);
    auto &bel_data = bel_info(chip_info, bel);
    NPNR_ASSERT(pin_index >= 0 && pin_index < bel_data.num_bel_wires);
    const int32_t *types = bel_data.types.get();
    return PortType(types[pin_index]);
}

// -----------------------------------------------------------------------

WireId Arch::getWireByName(IdStringList name) const
{
    WireId ret;
    if (name.ids.size() != 2) {
        return WireId();
    }

    setup_byname();

    auto iter = site_by_name.find(name.ids[0]);
    if (iter != site_by_name.end()) {
        int tile;
        int site;
        std::tie(tile, site) = iter->second;
        auto &tile_info = chip_info->tile_types[chip_info->tiles[tile].type];
        IdString wirename = name.ids[1];
        for (int i = 0; i < tile_info.wire_data.ssize(); i++) {
            if (tile_info.wire_data[i].site == site && tile_info.wire_data[i].name == wirename.index) {
                ret.tile = tile;
                ret.index = i;
                break;
            }
        }
    } else {
        int tile = tile_by_name.at(name.ids[0]);
        auto &tile_info = chip_info->tile_types[chip_info->tiles[tile].type];
        IdString wirename = name.ids[1];
        for (int i = 0; i < tile_info.wire_data.ssize(); i++) {
            if (tile_info.wire_data[i].site == -1 && tile_info.wire_data[i].name == wirename.index) {
                int32_t node = chip_info->tiles[tile].tile_wire_to_node[i];
                if (node == -1) {
                    // Not a nodal wire
                    ret.tile = tile;
                    ret.index = i;
                } else {
                    // Is a nodal wire, set tile to -1
                    ret.tile = -1;
                    ret.index = node;
                }
                break;
            }
        }
    }

    return ret;
}

IdString Arch::getWireType(WireId wire) const
{
    int tile = wire.tile, index = wire.index;
    if (tile == -1) {
        // Nodal wire
        const TileWireRefPOD &wr = chip_info->nodes[wire.index].tile_wires[0];
        tile = wr.tile;
        index = wr.index;
    }
    auto &w2t = chip_info->tiles[tile].tile_wire_to_type;
    if (index >= w2t.ssize())
        return IdString();
    int wire_type = w2t[index];
    if (wire_type == -1)
        return IdString();
    return IdString(chip_info->wire_types[wire_type].name);
}

bool Arch::is_site_wire(WireId wire) const
{
    if (wire.tile == -1)
        return false;
    const auto &tile_type = loc_info(chip_info, wire);
    return tile_type.wire_data[wire.index].site != -1;
}

WireCategory Arch::get_wire_category(WireId wire) const
{
    int tile = wire.tile, index = wire.index;
    if (tile == -1) {
        // Nodal wire
        const TileWireRefPOD &wr = chip_info->nodes[wire.index].tile_wires[0];
        tile = wr.tile;
        index = wr.index;
    }
    auto &w2t = chip_info->tiles[tile].tile_wire_to_type;
    if (index >= w2t.ssize())
        return WIRE_CAT_GENERAL;
    int wire_type = w2t[index];
    if (wire_type == -1)
        return WIRE_CAT_GENERAL;
    return WireCategory(chip_info->wire_types[wire_type].category);
}

std::vector<std::pair<IdString, std::string>> Arch::getWireAttrs(WireId wire) const { return {}; }

// -----------------------------------------------------------------------

PipId Arch::getPipByName(IdStringList name) const
{
    // PIP name structure:
    // Tile PIP: <tile name>/<source wire name>.<destination wire name>
    // Site PIP: <site name>/<bel name>/<input bel pin name>
    // Site pin: <site name>/<bel name>
    // Psuedo site PIP: <site name>/<source wire name>.<destination wire name>

    setup_byname();

    if (name.ids.size() == 3) {
        // This is a Site PIP.
        IdString site_name = name.ids[0];
        IdString belname = name.ids[1];
        IdString pinname = name.ids[2];

        int tile;
        int site;
        std::tie(tile, site) = site_by_name.at(site_name);
        auto tile_type_idx = chip_info->tiles[tile].type;
        auto &tile_info = chip_info->tile_types[tile_type_idx];

        std::array<IdString, 2> ids{name.ids[0], belname};
        BelId bel = getBelByName(IdStringList(ids));
        NPNR_ASSERT(bel != BelId());

        int pin_index = get_bel_pin_index(bel, pinname);
        NPNR_ASSERT(pin_index >= 0);

        for (int i = 0; i < tile_info.pip_data.ssize(); i++) {
            if (tile_info.pip_data[i].site == site && tile_info.pip_data[i].bel == bel.index &&
                tile_info.pip_data[i].extra_data == pin_index) {

                PipId ret;
                ret.tile = tile;
                ret.index = i;
                return ret;
            }
        }
    } else {
        auto iter = site_by_name.find(name.ids[0]);
        if (iter != site_by_name.end()) {
            // This is either a site pin or a psuedo site pip.
            // psuedo site pips are <site>/<src site wire>.<dst site wire>
            // site pins are <site>/<bel>
            int tile;
            int site;
            std::tie(tile, site) = iter->second;
            auto tile_type_idx = chip_info->tiles[tile].type;
            auto &tile_info = chip_info->tile_types[tile_type_idx];

            std::string pip_second = name.ids[1].str(this);
            auto split = pip_second.find('.');
            if (split == std::string::npos) {
                // This is a site pin!
                BelId bel = getBelByName(name);
                NPNR_ASSERT(bel != BelId());

                for (int i = 0; i < tile_info.pip_data.ssize(); i++) {
                    if (tile_info.pip_data[i].site == site && tile_info.pip_data[i].bel == bel.index) {

                        PipId ret;
                        ret.tile = tile;
                        ret.index = i;
                        return ret;
                    }
                }
            } else {
                // This is a psuedo site pip!
                IdString src_site_wire = id(pip_second.substr(0, split));
                IdString dst_site_wire = id(pip_second.substr(split + 1));
                int32_t src_index = -1;
                int32_t dst_index = -1;

                for (int i = 0; i < tile_info.wire_data.ssize(); i++) {
                    if (tile_info.wire_data[i].site == site && tile_info.wire_data[i].name == src_site_wire.index) {
                        src_index = i;
                        if (dst_index != -1) {
                            break;
                        }
                    }
                    if (tile_info.wire_data[i].site == site && tile_info.wire_data[i].name == dst_site_wire.index) {
                        dst_index = i;
                        if (src_index != -1) {
                            break;
                        }
                    }
                }

                NPNR_ASSERT(src_index != -1);
                NPNR_ASSERT(dst_index != -1);

                for (int i = 0; i < tile_info.pip_data.ssize(); i++) {
                    if (tile_info.pip_data[i].site == site && tile_info.pip_data[i].src_index == src_index &&
                        tile_info.pip_data[i].dst_index == dst_index) {

                        PipId ret;
                        ret.tile = tile;
                        ret.index = i;
                        return ret;
                    }
                }
            }
        } else {
            int tile = tile_by_name.at(name.ids[0]);
            size_t tile_type_idx = chip_info->tiles[tile].type;
            auto &tile_info = chip_info->tile_types[tile_type_idx];

            std::string pip_second = name.ids[1].str(this);
            auto spn = split_identifier_name_dot(pip_second);
            auto src_wire_name = id(spn.first);
            auto dst_wire_name = id(spn.second);

            int32_t src_index = -1;
            int32_t dst_index = -1;
            for (int i = 0; i < tile_info.wire_data.ssize(); i++) {
                if (tile_info.wire_data[i].site == -1 && tile_info.wire_data[i].name == src_wire_name.index) {
                    src_index = i;
                    if (dst_index != -1) {
                        break;
                    }
                }
                if (tile_info.wire_data[i].site == -1 && tile_info.wire_data[i].name == dst_wire_name.index) {
                    dst_index = i;
                    if (src_index != -1) {
                        break;
                    }
                }
            }

            NPNR_ASSERT(src_index != -1);
            NPNR_ASSERT(dst_index != -1);

            for (int i = 0; i < tile_info.pip_data.ssize(); i++) {
                if (tile_info.pip_data[i].src_index == src_index && tile_info.pip_data[i].dst_index == dst_index) {

                    PipId ret;
                    ret.tile = tile;
                    ret.index = i;
                    return ret;
                }
            }
        }
    }

    return PipId();
}

IdStringList Arch::getPipName(PipId pip) const
{
    // PIP name structure:
    // Tile PIP: <tile name>/<source wire name>.<destination wire name>
    // Psuedo site PIP: <site name>/<input site wire>.<output site wire>
    // Site PIP: <site name>/<bel name>/<input bel pin name>
    // Site pin: <site name>/<bel name>
    NPNR_ASSERT(pip != PipId());
    auto &tile = chip_info->tiles[pip.tile];
    auto &tile_type = loc_info(chip_info, pip);
    auto &pip_info = tile_type.pip_data[pip.index];
    if (pip_info.site != -1) {
        // This is either a site pin or a site pip.
        auto &site = get_site_inst(pip);
        auto &bel = tile_type.bel_data[pip_info.bel];
        IdString bel_name(bel.name);
        if (bel.category == BEL_CATEGORY_LOGIC) {
            // This is a psuedo pip
            IdString src_wire_name = IdString(tile_type.wire_data[pip_info.src_index].name);
            IdString dst_wire_name = IdString(tile_type.wire_data[pip_info.dst_index].name);
            IdString pip = id(src_wire_name.str(this) + "." + dst_wire_name.str(this));
            std::array<IdString, 2> ids{id(site.name.get()), pip};
            return IdStringList(ids);

        } else if (bel.category == BEL_CATEGORY_ROUTING) {
            // This is a site pip.
            IdString pin_name(bel.ports[pip_info.extra_data]);
            std::array<IdString, 3> ids{id(site.name.get()), bel_name, pin_name};
            return IdStringList(ids);
        } else {
            NPNR_ASSERT(bel.category == BEL_CATEGORY_SITE_PORT);
            // This is a site pin, just the name of the BEL is a unique identifier.
            std::array<IdString, 2> ids{id(site.name.get()), bel_name};
            return IdStringList(ids);
        }
    } else {
        // This is a tile pip.
        IdString src_wire_name = IdString(tile_type.wire_data[pip_info.src_index].name);
        IdString dst_wire_name = IdString(tile_type.wire_data[pip_info.dst_index].name);
        IdString pip = id(src_wire_name.str(this) + "." + dst_wire_name.str(this));
        std::array<IdString, 2> ids{id(std::string(tile.name.get())), pip};
        return IdStringList(ids);
    }
}

IdString Arch::getPipType(PipId pip) const { return id("PIP"); }

std::vector<std::pair<IdString, std::string>> Arch::getPipAttrs(PipId pip) const { return {}; }

// -----------------------------------------------------------------------

BelId Arch::getBelByLocation(Loc loc) const
{
    BelId bi;
    if (loc.x >= chip_info->width || loc.y >= chip_info->height)
        return BelId();
    bi.tile = get_tile_index(loc);
    auto &li = loc_info(chip_info, bi);

    if (loc.z >= li.bel_data.ssize()) {
        return BelId();
    } else {
        bi.index = loc.z;
        return bi;
    }
}

std::vector<std::pair<IdString, std::string>> Arch::getBelAttrs(BelId bel) const { return {}; }

// -----------------------------------------------------------------------

BoundingBox Arch::getRouteBoundingBox(WireId src, WireId dst) const
{
    int dst_tile = dst.tile == -1 ? chip_info->nodes[dst.index].tile_wires[0].tile : dst.tile;
    int src_tile = src.tile == -1 ? chip_info->nodes[src.index].tile_wires[0].tile : src.tile;

    int src_x, src_y;
    get_tile_x_y(src_tile, &src_x, &src_y);

    int x0 = src_x, x1 = src_x, y0 = src_y, y1 = src_y;

    int dst_x, dst_y;
    get_tile_x_y(dst_tile, &dst_x, &dst_y);

    auto expand = [&](int x, int y) {
        x0 = std::min(x0, x);
        x1 = std::max(x1, x);
        y0 = std::min(y0, y);
        y1 = std::max(y1, y);
    };

    expand(dst_x, dst_y);

    if (source_locs.count(src))
        expand(source_locs.at(src).x, source_locs.at(src).y);

    if (sink_locs.count(dst)) {
        expand(sink_locs.at(dst).x, sink_locs.at(dst).y);
    }

    return {x0, y0, x1, y1};
}

bool Arch::getBudgetOverride(const NetInfo *net_info, const PortRef &sink, delay_t &budget) const { return false; }

// -----------------------------------------------------------------------

bool Arch::pack()
{
    decode_lut_cells();
    expand_macros();
    merge_constant_nets();
    pack_ports();
    pack_default_conns();
    pack_cluster();
    return true;
}

static void prepare_for_placement(Context *ctx)
{
    ctx->remove_site_routing();

    // Re-map BEL pins without constant pins
    for (BelId bel : ctx->getBels()) {
        CellInfo *cell = ctx->getBoundBelCell(bel);
        if (cell != nullptr && cell->cell_mapping != -1) {
            ctx->map_cell_pins(cell, cell->cell_mapping, /*bind_constants=*/false);
        }
    }
}

bool Arch::place()
{
    // Before placement, ripup placement specific bindings and unmask all cell
    // pins.
    getCtx()->check();
    prepare_for_placement(getCtx());
    getCtx()->check();
#ifdef IDEMPOTENT_CHECK
    prepare_for_placement(getCtx());
    getCtx()->check();
#endif

    place_constraints();
    place_globals();

    std::string placer = str_or_default(settings, id("placer"), defaultPlacer);
    if (placer == "heap") {
        PlacerHeapCfg cfg(getCtx());
        cfg.criticalityExponent = 7;
        cfg.alpha = 0.08;
        cfg.beta = 0.4;
        cfg.placeAllAtOnce = true;
        cfg.hpwl_scale_x = 1;
        cfg.hpwl_scale_y = 2;
        cfg.spread_scale_x = 2;
        cfg.spread_scale_y = 1;
        cfg.solverTolerance = 0.6e-6;
        if (!placer_heap(getCtx(), cfg))
            return false;
    } else if (placer == "sa") {
        if (!placer1(getCtx(), Placer1Cfg(getCtx())))
            return false;
    } else {
        log_error("FPGA interchange architecture does not support placer '%s'\n", placer.c_str());
    }

    getCtx()->attrs[getCtx()->id("step")] = std::string("place");
    archInfoToAttributes();

    // Print site LUT mapping caching stats
    if (!getCtx()->arch_args.disable_lut_mapping_cache) {
        log_info("Site LUT mapping cache stats:\n");
        log_info("    miss ratio: %.1f%%\n", getCtx()->site_lut_mapping_cache.getMissRatio() * 100.0f);
        log_info("    peak size : %zuMB (%zu items)\n", getCtx()->site_lut_mapping_cache.getSizeMB(),
                 getCtx()->site_lut_mapping_cache.getCount());
    }

    getCtx()->check();

    return true;
}

static void prepare_sites_for_routing(Context *ctx)
{
    // Reset site routing and remove masked cell pins from previous router run
    // (if any).
    ctx->remove_site_routing();

    // Re-map BEL pins with constant pins
    for (BelId bel : ctx->getBels()) {
        CellInfo *cell = ctx->getBoundBelCell(bel);
        if (cell != nullptr && cell->cell_mapping != -1) {
            ctx->map_cell_pins(cell, cell->cell_mapping, /*bind_constants=*/true);
        }
    }

    // Clear the site routing cache. This is because routing at this stage is done with the extra constraint of blocked
    // pins to ensure a routeable pin choice.
    ctx->site_routing_cache.clear();

    // Clear the LUT mapping cache
    ctx->site_lut_mapping_cache.clear();

    // Have site router bind site routing (via bindPip and bindWire).
    // This is important so that the pseudo pips are correctly blocked prior
    // to handing the design to the generalized router algorithms.
    for (auto &tile_pair : ctx->tileStatus) {
        for (auto &site_router : tile_pair.second.sites) {
            if (site_router.cells_in_site.empty()) {
                continue;
            }

            site_router.bindSiteRouting(ctx);
        }

        tile_pair.second.pseudo_pip_model.prepare_for_routing(ctx, tile_pair.second.sites);
    }

    // Fixup LUT vcc pins.
    IdString vcc_net_name(ctx->chip_info->constants->vcc_net_name);
    IdString gnd_net_name(ctx->chip_info->constants->gnd_net_name);

    IdString const_net_name(ctx->chip_info->constants->best_constant_net);
    NPNR_ASSERT(const_net_name == IdString() || const_net_name == vcc_net_name || const_net_name == gnd_net_name);

    // FIXME: Use VCC if the architecture does not device the best constant
    if (const_net_name == IdString()) {
        const_net_name = vcc_net_name;
    }

    for (BelId bel : ctx->getBels()) {
        CellInfo *cell = ctx->getBoundBelCell(bel);
        if (cell == nullptr) {
            continue;
        }

        for (const auto &it : cell->lut_cell.pin_connections) {
            const auto &bel_pin = it.first;
            const auto &conn = it.second;

            // Connected to an active signal or unconnected
            if (conn == LutCell::PinConnection::Signal || conn == LutCell::PinConnection::Unconnected) {
                continue;
            }

            // We can't rely on bel pins not clashing with cell names (for Xilinx they use different naming schemes, for
            // Nexus they are the same) so add a prefix to the bel pin name to disambiguate it
            IdString cell_pin = ctx->idf("%s_PHYS", ctx->nameOf(bel_pin));

            PortInfo port_info;
            port_info.name = cell_pin;
            port_info.type = PORT_IN;
            port_info.net = nullptr;

#ifdef DEBUG_LUT_MAPPING
            if (ctx->verbose) {
                log_info("%s must be tied to %s, tying now\n", ctx->nameOfWire(lut_pin_wire),
                         LutCell::nameOfPinConnection(conn).c_str());
            }
#endif

            IdString tie_net_name;
            switch (conn) {
            case LutCell::PinConnection::Vcc:
                tie_net_name = vcc_net_name;
                break;
            case LutCell::PinConnection::Gnd:
                tie_net_name = gnd_net_name;
                break;
            case LutCell::PinConnection::Const:
                tie_net_name = const_net_name;
                break;
            default:
                // Should never happen
                NPNR_ASSERT_FALSE(
                        stringf("Invalid LUT cell pin connection '%s'", LutCell::nameOfPinConnection(conn).c_str())
                                .c_str());
                break;
            }

            auto result = cell->ports.emplace(cell_pin, port_info);
            if (result.second) {
                cell->cell_bel_pins[cell_pin].push_back(bel_pin);
                ctx->connectPort(tie_net_name, cell->name, cell_pin);
                cell->const_ports.emplace(cell_pin);
            } else {
                NPNR_ASSERT(result.first->second.net == ctx->getNetByAlias(tie_net_name));
                auto result2 = cell->cell_bel_pins.emplace(cell_pin, std::vector<IdString>({bel_pin}));
                NPNR_ASSERT(result2.first->second.at(0) == bel_pin);
                NPNR_ASSERT(result2.first->second.size() == 1);
            }
        }
    }
}

bool Arch::route()
{
    getCtx()->check();
    prepare_sites_for_routing(getCtx());
    getCtx()->check();
#ifdef IDEMPOTENT_CHECK
    prepare_sites_for_routing(getCtx());
    getCtx()->check();
#endif

    std::string router = str_or_default(settings, id("router"), defaultRouter);

    // Disallow site routing during general routing.  This is because
    // "prepare_sites_for_routing" has already assigned routing for all sites
    // in the design, and if the router wants to route-thru a site, it *MUST*
    // use a pseudo-pip.
    //
    // It is not legal in the FPGA interchange to enter a site and not
    // terminate at a BEL pin.
    disallow_site_routing = true;

    route_globals();

    bool result;
    if (router == "router1") {
        result = router1(getCtx(), Router1Cfg(getCtx()));
    } else if (router == "router2") {
        router2(getCtx(), Router2Cfg(getCtx()));
        result = true;
    } else {
        log_error("FPGA interchange architecture does not support router '%s'\n", router.c_str());
    }

    disallow_site_routing = false;

    getCtx()->attrs[getCtx()->id("step")] = std::string("route");
    archInfoToAttributes();

    getCtx()->check();

    // Now that routing is complete, unmask BEL pins.
    unmask_bel_pins();

    getCtx()->check();

    return result;
}

// -----------------------------------------------------------------------

std::vector<GraphicElement> Arch::getDecalGraphics(DecalId decal) const { return {}; }

DecalXY Arch::getBelDecal(BelId bel) const
{
    DecalXY decalxy;
    return decalxy;
}

DecalXY Arch::getWireDecal(WireId wire) const
{
    DecalXY decalxy;
    return decalxy;
}

DecalXY Arch::getPipDecal(PipId pip) const { return {}; };

DecalXY Arch::getGroupDecal(GroupId pip) const { return {}; };

// -----------------------------------------------------------------------

delay_t Arch::estimateDelay(WireId src, WireId dst) const
{
#ifdef USE_LOOKAHEAD
    return lookahead.estimateDelay(getCtx(), src, dst);
#else
    // Note: Something is better than nothing when USE_LOOKAHEAD is not
    // defined.
    int src_tile = src.tile == -1 ? chip_info->nodes[src.index].tile_wires[0].tile : src.tile;
    int dst_tile = dst.tile == -1 ? chip_info->nodes[dst.index].tile_wires[0].tile : dst.tile;

    int src_x, src_y;
    get_tile_x_y(src_tile, &src_x, &src_y);

    int dst_x, dst_y;
    get_tile_x_y(dst_tile, &dst_x, &dst_y);

    delay_t base = 30 * std::min(std::abs(dst_x - src_x), 18) + 10 * std::max(std::abs(dst_x - src_x) - 18, 0) +
                   60 * std::min(std::abs(dst_y - src_y), 6) + 20 * std::max(std::abs(dst_y - src_y) - 6, 0) + 300;

    base = (base * 3) / 2;
    return base;
#endif
}

delay_t Arch::predictDelay(BelId src_bel, IdString src_pin, BelId dst_bel, IdString dst_pin) const
{
    // FIXME: Implement when adding timing-driven place and route.
    NPNR_UNUSED(src_pin);
    NPNR_UNUSED(dst_pin);
    int src_x, src_y;
    get_tile_x_y(src_bel.tile, &src_x, &src_y);

    int dst_x, dst_y;
    get_tile_x_y(dst_bel.tile, &dst_x, &dst_y);

    delay_t base = 30 * std::min(std::abs(dst_x - src_x), 18) + 10 * std::max(std::abs(dst_x - src_x) - 18, 0) +
                   60 * std::min(std::abs(dst_y - src_y), 6) + 20 * std::max(std::abs(dst_y - src_y) - 6, 0) + 300;

    base = (base * 3) / 2;
    return base;
}

bool Arch::getCellDelay(const CellInfo *cell, IdString fromPort, IdString toPort, DelayQuad &delay) const
{
    // FIXME: Implement when adding timing-driven place and route.
    return false;
}

TimingPortClass Arch::getPortTimingClass(const CellInfo *cell, IdString port, int &clockInfoCount) const
{
    // FIXME: Implement when adding timing-driven place and route.
    return TMG_IGNORE;
}

TimingClockingInfo Arch::getPortClockingInfo(const CellInfo *cell, IdString port, int index) const
{
    // FIXME: Implement when adding timing-driven place and route.
    TimingClockingInfo info;
    return info;
}

// -----------------------------------------------------------------------

void Arch::read_logical_netlist(const std::string &filename)
{
    FpgaInterchange::read_logical_netlist(getCtx(), filename);
}
void Arch::write_physical_netlist(const std::string &filename) const
{
    FpgaInterchange::write_physical_netlist(getCtx(), filename);
}

void Arch::parse_xdc(const std::string &filename)
{
    TclInterp interp(getCtx());
    auto result = Tcl_EvalFile(interp.interp, filename.c_str());
    if (result != TCL_OK) {
        log_error("Error in %s:%d => %s\n", filename.c_str(), Tcl_GetErrorLine(interp.interp),
                  Tcl_GetStringResult(interp.interp));
    }
}

std::string Arch::get_part() const
{
    // FIXME: Need a map between device / package / speed grade and part.
    return chip_info->name.get() + args.package + "-1";
}

// -----------------------------------------------------------------------

#ifdef WITH_HEAP
const std::string Arch::defaultPlacer = "heap";
#else
const std::string Arch::defaultPlacer = "sa";
#endif

const std::vector<std::string> Arch::availablePlacers = {"sa",
#ifdef WITH_HEAP
                                                         "heap"
#endif
};

const std::string Arch::defaultRouter = "router2";
const std::vector<std::string> Arch::availableRouters = {"router1", "router2"};

void Arch::map_cell_pins(CellInfo *cell, int32_t mapping, bool bind_constants)
{
    cell->cell_mapping = mapping;
    if (cell->lut_cell.pins.empty()) {
        cell->cell_bel_pins.clear();
        cell->masked_cell_bel_pins.clear();
    } else {
        std::vector<IdString> cell_pin_to_remove;
        for (auto port_pair : cell->cell_bel_pins) {
            if (!cell->lut_cell.lut_pins.count(port_pair.first)) {
                cell_pin_to_remove.push_back(port_pair.first);
            }
        }

        for (IdString cell_pin : cell_pin_to_remove) {
            NPNR_ASSERT(cell->cell_bel_pins.erase(cell_pin));
        }
    }

    for (IdString const_port : cell->const_ports) {
        disconnectPort(cell->name, const_port);
        NPNR_ASSERT(cell->ports.erase(const_port));
    }

    const CellBelMapPOD &cell_pin_map = chip_info->cell_map->cell_bel_map[mapping];

    IdString gnd_net_name(chip_info->constants->gnd_net_name);
    IdString vcc_net_name(chip_info->constants->vcc_net_name);

    for (const auto &pin_map : cell_pin_map.common_pins) {
        IdString cell_pin(pin_map.cell_pin);
        IdString bel_pin(pin_map.bel_pin);

        // Skip assigned LUT pins, as they are already mapped!
        if (cell->lut_cell.lut_pins.count(cell_pin) && cell->cell_bel_pins.count(cell_pin)) {
            continue;
        }

        if (cell_pin == id_GND) {
            if (bind_constants) {
                PortInfo port_info;
                port_info.name = bel_pin;
                port_info.type = PORT_IN;
                port_info.net = nullptr;

                auto result = cell->ports.emplace(bel_pin, port_info);
                if (result.second) {
                    cell->cell_bel_pins[bel_pin].push_back(bel_pin);
                    connectPort(gnd_net_name, cell->name, bel_pin);
                    cell->const_ports.emplace(bel_pin);
                } else {
                    NPNR_ASSERT(result.first->second.net == getNetByAlias(gnd_net_name));
                    auto result2 = cell->cell_bel_pins.emplace(bel_pin, std::vector<IdString>({bel_pin}));
                    NPNR_ASSERT(result2.first->second.at(0) == bel_pin);
                    NPNR_ASSERT(result2.first->second.size() == 1);
                }
            }
            continue;
        }

        if (cell_pin == id_VCC) {
            if (bind_constants) {
                PortInfo port_info;
                port_info.name = bel_pin;
                port_info.type = PORT_IN;
                port_info.net = nullptr;

                auto result = cell->ports.emplace(bel_pin, port_info);
                if (result.second) {
                    cell->cell_bel_pins[bel_pin].push_back(bel_pin);
                    connectPort(vcc_net_name, cell->name, bel_pin);
                    cell->const_ports.emplace(bel_pin);
                } else {
                    NPNR_ASSERT(result.first->second.net == getNetByAlias(vcc_net_name));
                    auto result2 = cell->cell_bel_pins.emplace(bel_pin, std::vector<IdString>({bel_pin}));
                    NPNR_ASSERT(result2.first->second.at(0) == bel_pin);
                    NPNR_ASSERT(result2.first->second.size() == 1);
                }
            }
            continue;
        }

        cell->cell_bel_pins[cell_pin].push_back(bel_pin);
    }

    for (const auto &parameter_pin_map : cell_pin_map.parameter_pins) {
        IdString param_key(parameter_pin_map.key);
        IdString param_value(parameter_pin_map.value);

        auto iter = cell->params.find(param_key);
        if (iter == cell->params.end()) {
            continue;
        }

        if (!cell_parameters.compare_property(getCtx(), cell->type, param_key, iter->second, param_value)) {
            continue;
        }

#ifdef DEBUG_CELL_PIN_MAPPING
        log_info("parameter match on param_key %s\n", param_key.c_str(this));
#endif

        for (const auto &pin_map : parameter_pin_map.pins) {
            IdString cell_pin(pin_map.cell_pin);
            IdString bel_pin(pin_map.bel_pin);
#ifdef DEBUG_CELL_PIN_MAPPING
            log_info(" %s => %s\n", cell_pin.c_str(this), bel_pin.c_str(this));
#endif

            // Skip assigned LUT pins, as they are already mapped!
            if (cell->lut_cell.lut_pins.count(cell_pin) && cell->cell_bel_pins.count(cell_pin)) {
                continue;
            }

            if (cell_pin == id_GND) {
                if (bind_constants) {
                    PortInfo port_info;
                    port_info.name = bel_pin;
                    port_info.type = PORT_IN;
                    port_info.net = nullptr;

                    auto result = cell->ports.emplace(bel_pin, port_info);
                    if (result.second) {
                        cell->cell_bel_pins[bel_pin].push_back(bel_pin);
                        connectPort(gnd_net_name, cell->name, bel_pin);
                        cell->const_ports.emplace(bel_pin);
                    } else {
                        NPNR_ASSERT(result.first->second.net == getNetByAlias(gnd_net_name));
                        auto result2 = cell->cell_bel_pins.emplace(bel_pin, std::vector<IdString>({bel_pin}));
                        NPNR_ASSERT(result2.first->second.at(0) == bel_pin);
                        NPNR_ASSERT(result2.first->second.size() == 1);
                    }
                }
                continue;
            }

            if (cell_pin == id_VCC) {
                if (bind_constants) {
                    PortInfo port_info;
                    port_info.name = bel_pin;
                    port_info.type = PORT_IN;
                    port_info.net = nullptr;

                    auto result = cell->ports.emplace(bel_pin, port_info);
                    if (result.second) {
                        cell->cell_bel_pins[bel_pin].push_back(bel_pin);
                        connectPort(vcc_net_name, cell->name, bel_pin);
                        cell->const_ports.emplace(bel_pin);
                    } else {
                        NPNR_ASSERT(result.first->second.net == getNetByAlias(vcc_net_name));
                        auto result2 = cell->cell_bel_pins.emplace(bel_pin, std::vector<IdString>({bel_pin}));
                        NPNR_ASSERT(result2.first->second.at(0) == bel_pin);
                        NPNR_ASSERT(result2.first->second.size() == 1);
                    }
                }
                continue;
            }

            cell->cell_bel_pins[cell_pin].push_back(bel_pin);
        }
    }

#ifdef DEBUG_CELL_PIN_MAPPING
    log_info("Pin mapping for cell %s (type: %s)\n", cell->name.c_str(getCtx()), cell->type.c_str(getCtx()));
    for (auto &pin_pair : cell->cell_bel_pins) {
        log_info(" %s =>", pin_pair.first.c_str(getCtx()));
        for (IdString bel_pin : pin_pair.second) {
            log(" %s", bel_pin.c_str(getCtx()));
        }
        log("\n");
    }
#endif
}

void Arch::map_port_pins(BelId bel, CellInfo *cell) const
{
    IdStringRange pins = getBelPins(bel);
    IdString pin = get_only_value(pins);

    NPNR_ASSERT(cell->ports.size() == 1);
    cell->cell_bel_pins[cell->ports.begin()->first].clear();
    cell->cell_bel_pins[cell->ports.begin()->first].push_back(pin);
}

bool Arch::is_net_within_site(const NetInfo &net) const
{
    if (net.driver.cell == nullptr || net.driver.cell->bel == BelId()) {
        return false;
    }

    BelId driver = net.driver.cell->bel;
    int32_t site = bel_info(chip_info, driver).site;
    NPNR_ASSERT(site >= 0);

    for (const auto &user : net.users) {
        if (user.cell == nullptr || user.cell->bel == BelId()) {
            return false;
        }
        BelId user_bel = user.cell->bel;

        if (user_bel.tile != driver.tile) {
            return false;
        }

        if (bel_info(chip_info, user_bel).site != site) {
            return false;
        }
    }

    return true;
}

size_t Arch::get_cell_type_index(IdString cell_type) const
{
    const CellMapPOD &cell_map = *chip_info->cell_map;
    int cell_offset = cell_type.index - cell_map.cell_names[0];
    if ((cell_offset < 0 || cell_offset >= cell_map.cell_names.ssize())) {
        log_error("Cell %s is not a placable element.\n", cell_type.c_str(this));
    }
    NPNR_ASSERT(cell_map.cell_names[cell_offset] == cell_type.index);

    return cell_offset;
}

void Arch::merge_constant_nets()
{
    NetInfo *gnd_net = nullptr;
    NetInfo *vcc_net = nullptr;

    bool need_gnd_source = false;
    bool need_vcc_source = false;

    IdString gnd_net_name(chip_info->constants->gnd_net_name);
    IdString gnd_cell_type(chip_info->constants->gnd_cell_name);
    IdString gnd_cell_port(chip_info->constants->gnd_cell_port);

    auto gnd_iter = nets.find(gnd_net_name);
    if (gnd_iter != nets.end()) {
        NPNR_ASSERT(gnd_iter->second->driver.cell != nullptr);
        NPNR_ASSERT(gnd_iter->second->driver.cell->type == gnd_cell_type);
        NPNR_ASSERT(gnd_iter->second->driver.port == gnd_cell_port);

        gnd_net = gnd_iter->second.get();
    } else {
        gnd_net = createNet(gnd_net_name);
        need_gnd_source = true;
    }

    IdString vcc_net_name(chip_info->constants->vcc_net_name);
    IdString vcc_cell_type(chip_info->constants->vcc_cell_name);
    IdString vcc_cell_port(chip_info->constants->vcc_cell_port);

    auto vcc_iter = nets.find(vcc_net_name);
    if (vcc_iter != nets.end()) {
        NPNR_ASSERT(vcc_iter->second->driver.cell != nullptr);
        NPNR_ASSERT(vcc_iter->second->driver.cell->type == vcc_cell_type);
        NPNR_ASSERT(vcc_iter->second->driver.port == vcc_cell_port);

        vcc_net = vcc_iter->second.get();
    } else {
        vcc_net = createNet(vcc_net_name);
        need_vcc_source = true;
    }

    std::vector<IdString> other_gnd_nets;
    std::vector<IdString> other_vcc_nets;

    for (auto &net_pair : nets) {
        if (net_pair.first == gnd_net_name) {
            NPNR_ASSERT(net_pair.second.get() == gnd_net);
            continue;
        }

        if (net_pair.first == vcc_net_name) {
            NPNR_ASSERT(net_pair.second.get() == vcc_net);
            continue;
        }

        NetInfo *net = net_pair.second.get();
        if (net->driver.cell == nullptr) {
            continue;
        }

        if (net->driver.cell->type == gnd_cell_type) {
            NPNR_ASSERT(net->driver.port == gnd_cell_port);

            other_gnd_nets.push_back(net_pair.first);

            if (need_gnd_source) {
                IdString driver_cell = net->driver.cell->name;
                disconnectPort(driver_cell, gnd_cell_port);
                connectPort(gnd_net_name, driver_cell, gnd_cell_port);
                need_gnd_source = false;
            }

            NPNR_ASSERT(net->driver.port == gnd_cell_port);
            indexed_store<PortRef> users_copy = net->users;
            for (const PortRef &port_ref : users_copy) {
                IdString cell = port_ref.cell->name;
                disconnectPort(cell, port_ref.port);
                connectPort(gnd_net_name, cell, port_ref.port);
            }

            continue;
        }

        if (net->driver.cell->type == vcc_cell_type) {
            NPNR_ASSERT(net->driver.port == vcc_cell_port);

            other_vcc_nets.push_back(net_pair.first);

            if (need_vcc_source) {
                IdString driver_cell = net->driver.cell->name;
                disconnectPort(driver_cell, vcc_cell_port);
                connectPort(vcc_net_name, driver_cell, vcc_cell_port);
                need_vcc_source = false;
            }

            NPNR_ASSERT(net->driver.port == vcc_cell_port);
            indexed_store<PortRef> users_copy = net->users;
            for (const PortRef &port_ref : users_copy) {
                IdString cell = port_ref.cell->name;
                disconnectPort(cell, port_ref.port);
                connectPort(vcc_net_name, cell, port_ref.port);
            }
        }
    }

    for (IdString other_gnd_net : other_gnd_nets) {
        NetInfo *net = getNetByAlias(other_gnd_net);
        NPNR_ASSERT(net->users.empty());
        if (net->driver.cell) {
            PortRef driver = net->driver;
            IdString cell_to_remove = driver.cell->name;
            disconnectPort(driver.cell->name, driver.port);
            NPNR_ASSERT(cells.erase(cell_to_remove));
        }
    }

    for (IdString other_vcc_net : other_vcc_nets) {
        NetInfo *net = getNetByAlias(other_vcc_net);
        NPNR_ASSERT(net->users.empty());
        if (net->driver.cell) {
            PortRef driver = net->driver;
            IdString cell_to_remove = driver.cell->name;
            disconnectPort(driver.cell->name, driver.port);
            NPNR_ASSERT(cells.erase(cell_to_remove));
        }
    }

    for (IdString other_gnd_net : other_gnd_nets) {
        NPNR_ASSERT(nets.erase(other_gnd_net));
        gnd_net->aliases.push_back(other_gnd_net);
        net_aliases[other_gnd_net] = gnd_net_name;
    }

    for (IdString other_vcc_net : other_vcc_nets) {
        NPNR_ASSERT(nets.erase(other_vcc_net));
        vcc_net->aliases.push_back(other_vcc_net);
        net_aliases[other_vcc_net] = vcc_net_name;
    }

    if (need_gnd_source) {
        CellInfo *gnd_cell = createCell(gnd_cell_type, gnd_cell_type);
        gnd_cell->addOutput(gnd_cell_port);
        connectPort(gnd_net_name, gnd_cell_type, gnd_cell_port);
    }

    if (need_vcc_source) {
        CellInfo *vcc_cell = createCell(vcc_cell_type, vcc_cell_type);
        vcc_cell->addOutput(vcc_cell_port);
        connectPort(vcc_net_name, vcc_cell_type, vcc_cell_port);
    }
}

const std::vector<IdString> &Arch::getBelPinsForCellPin(const CellInfo *cell_info, IdString pin) const
{
    auto iter = cell_info->cell_bel_pins.find(pin);
    if (iter == cell_info->cell_bel_pins.end()) {
        return no_pins;
    } else {
        return iter->second;
    }
}

void Arch::report_invalid_bel(BelId bel, CellInfo *cell) const
{
    int32_t mapping = bel_info(chip_info, bel).pin_map[get_cell_type_index(cell->type)];
    NPNR_ASSERT(mapping < 0);
    log_error("Cell %s (%s) cannot be placed at BEL %s (mapping %d)\n", cell->name.c_str(this), cell->type.c_str(this),
              nameOfBel(bel), mapping);
}

void Arch::decode_lut_cells()
{
    for (auto &cell_pair : cells) {
        CellInfo *cell = cell_pair.second.get();
        auto iter = lut_cells.find(cell->type);
        if (iter == lut_cells.end()) {
            cell->lut_cell.pins.clear();
            cell->lut_cell.equation.clear();
            continue;
        }

        const LutCellPOD &lut_cell = *iter->second;

        cell->lut_cell.pins.reserve(lut_cell.input_pins.size());
        for (uint32_t pin : lut_cell.input_pins) {
            cell->lut_cell.pins.push_back(IdString(pin));
            cell->lut_cell.lut_pins.emplace(IdString(pin));
        }

        IdString equation_parameter(lut_cell.parameter);
        const Property &equation = cell->params.at(equation_parameter);
        cell->lut_cell.equation.resize(1 << cell->lut_cell.pins.size());

        cell->lut_cell.equation = cell_parameters.parse_int_like(getCtx(), cell->type, equation_parameter, equation);
    }
}

void Arch::remove_pip_pseudo_wires(PipId pip, NetInfo *net)
{
    WireId wire;
    wire.tile = pip.tile;
    const PipInfoPOD &pip_data = pip_info(chip_info, pip);
    for (int32_t wire_index : pip_data.pseudo_cell_wires) {
        NPNR_ASSERT(wire_index != -1);
        wire.index = wire_index;

        auto iter = wire_to_net.find(wire);
        NPNR_ASSERT(iter != wire_to_net.end());
        // This wire better already have been assigned to this net!
        if (iter->second != net) {
            if (iter->second == nullptr) {
                log_error("Wire %s part of pseudo pip %s but net is null\n", nameOfWire(wire), nameOfPip(pip));
            } else {
                log_error("Wire %s part of pseudo pip %s but net is '%s' instead of net '%s'\n", nameOfWire(wire),
                          nameOfPip(pip), iter->second->name.c_str(this), net->name.c_str(this));
            }
        }

        auto wire_iter = net->wires.find(wire);
        if (wire_iter != net->wires.end()) {
#ifdef DEBUG_BINDING
            if (getCtx()->verbose) {
                log_info("Removing %s from net %s, but it's in net wires\n", nameOfWire(wire), net->name.c_str(this));
            }
#endif
            // This wire is part of net->wires, make sure it has no pip,
            // but leave it alone.  It will get cleaned up via
            // unbindWire.
        } else {
            // This wire is not in net->wires, update wire_to_net.
#ifdef DEBUG_BINDING
            if (getCtx()->verbose) {
                log_info("Removing %s from net %s in remove_pip_pseudo_wires\n", nameOfWire(wire),
                         net->name.c_str(this));
            }
#endif
            iter->second = nullptr;
        }
    }

    if (pip_data.pseudo_cell_wires.size() > 0) {
        get_tile_status(pip.tile).pseudo_pip_model.unbindPip(getCtx(), pip);
    }
}

void Arch::assign_net_to_wire(WireId wire, NetInfo *net, const char *src, bool require_empty)
{
#ifdef DEBUG_BINDING
    if (getCtx()->verbose) {
        log_info("Assigning wire %s to %s from %s\n", nameOfWire(wire), net->name.c_str(this), src);
    }
#endif
    NPNR_ASSERT(net != nullptr);
    auto result = wire_to_net.emplace(wire, net);
    if (!result.second) {
        // This wire was already in the map, make sure this assignment was
        // legal.
        if (require_empty) {
            NPNR_ASSERT(result.first->second == nullptr);
        } else {
            NPNR_ASSERT(result.first->second == nullptr || result.first->second == net);
        }
        result.first->second = net;
    }
}

void Arch::unassign_wire(WireId wire)
{
    NPNR_ASSERT(wire != WireId());
#ifdef DEBUG_BINDING
    if (getCtx()->verbose) {
        log_info("unassign_wire %s\n", nameOfWire(wire));
    }
#endif

    auto iter = wire_to_net.find(wire);
    NPNR_ASSERT(iter != wire_to_net.end());

    NetInfo *net = iter->second;
    NPNR_ASSERT(net != nullptr);

    auto &net_wires = net->wires;
    auto it = net_wires.find(wire);
    NPNR_ASSERT(it != net_wires.end());

    auto pip = it->second.pip;
    if (pip != PipId()) {
#ifdef DEBUG_BINDING
        if (getCtx()->verbose) {
            log_info("Removing pip %s because it was used to reach wire %s\n", nameOfPip(pip), nameOfWire(wire));
        }
#endif
        auto pip_iter = pip_to_net.find(pip);
        NPNR_ASSERT(pip_iter != pip_to_net.end());
        NPNR_ASSERT(pip_iter->second == net);
        pip_iter->second = nullptr;
        remove_pip_pseudo_wires(pip, net);
    }

    net_wires.erase(it);
#ifdef DEBUG_BINDING
    if (getCtx()->verbose) {
        log_info("Removing %s from net %s in unassign_wire\n", nameOfWire(wire), net->name.c_str(this));
    }
#endif
    iter->second = nullptr;
}

void Arch::unbindPip(PipId pip)
{
    NPNR_ASSERT(pip != PipId());
#ifdef DEBUG_BINDING
    if (getCtx()->verbose) {
        log_info("unbindPip %s\n", nameOfPip(pip));
    }
#endif

    auto pip_iter = pip_to_net.find(pip);
    NPNR_ASSERT(pip_iter != pip_to_net.end());
    NetInfo *net = pip_iter->second;
    NPNR_ASSERT(net != nullptr);

    WireId dst = getPipDstWire(pip);
    auto wire_iter = wire_to_net.find(dst);
    NPNR_ASSERT(wire_iter != wire_to_net.end());
    NPNR_ASSERT(wire_iter->second == net);

    remove_pip_pseudo_wires(pip, net);

    // Clear the net now.
    pip_iter->second = nullptr;
#ifdef DEBUG_BINDING
    if (getCtx()->verbose) {
        log_info("Removing %s from net %s in unbindPip\n", nameOfWire(dst), net->name.c_str(this));
    }
#endif
    wire_iter->second = nullptr;
    NPNR_ASSERT(net->wires.erase(dst) == 1);

    refreshUiPip(pip);
    refreshUiWire(dst);
}

void Arch::bindPip(PipId pip, NetInfo *net, PlaceStrength strength)
{
    NPNR_ASSERT(pip != PipId());
#ifdef DEBUG_BINDING
    if (getCtx()->verbose) {
        log_info("bindPip %s (%d/%d) to net %s\n", nameOfPip(pip), pip.tile, pip.index, net->name.c_str(this));
    }
#endif
    WireId dst = getPipDstWire(pip);
    NPNR_ASSERT(dst != WireId());

    {
        // Pip should not already be assigned to anything.
        auto result = pip_to_net.emplace(pip, net);
        if (!result.second) {
            NPNR_ASSERT(result.first->second == nullptr);
            result.first->second = net;
        }
    }

    assign_net_to_wire(dst, net, "bindPip", /*require_empty=*/true);
    assign_pip_pseudo_wires(pip, net);

    {
        auto result = net->wires.emplace(dst, PipMap{pip, strength});
        NPNR_ASSERT(result.second);
    }

    refreshUiPip(pip);
    refreshUiWire(dst);
}

void Arch::bindWire(WireId wire, NetInfo *net, PlaceStrength strength)
{
    NPNR_ASSERT(wire != WireId());
#ifdef DEBUG_BINDING
    if (getCtx()->verbose) {
        log_info("bindWire %s to net %s\n", nameOfWire(wire), net->name.c_str(this));
    }
#endif
    assign_net_to_wire(wire, net, "bindWire", /*require_empty=*/true);
    auto &pip_map = net->wires[wire];
    pip_map.pip = PipId();
    pip_map.strength = strength;
    refreshUiWire(wire);
}

bool Arch::checkPipAvailForNet(PipId pip, const NetInfo *net) const
{
    NPNR_ASSERT(pip != PipId());
    auto pip_iter = pip_to_net.find(pip);
    if (pip_iter != pip_to_net.end() && pip_iter->second != nullptr) {
        bool pip_blocked = false;
        if (net == nullptr) {
            pip_blocked = true;
        } else {
            if (net != pip_iter->second) {
                pip_blocked = true;
            }
        }
        if (pip_blocked) {
#ifdef DEBUG_BINDING
            if (getCtx()->verbose) {
                log_info("Pip %s (%d/%d) is not available, tied to net %s\n", getCtx()->nameOfPip(pip), pip.tile,
                         pip.index, pip_iter->second->name.c_str(getCtx()));
            }
#endif
            NPNR_ASSERT(pip_iter->first == pip);
            return false;
        }
    }

    WireId src = getPipSrcWire(pip);
    WireId dst = getPipDstWire(pip);

    auto wire_iter = wire_to_net.find(dst);
    if (wire_iter != wire_to_net.end()) {
        NetInfo *wire_net = wire_iter->second;
        if (wire_net != nullptr) {
            auto net_iter = wire_net->wires.find(dst);
            if (net_iter != wire_net->wires.end()) {
                if (net == nullptr) {
#ifdef DEBUG_BINDING
                    if (getCtx()->verbose) {
                        log_info("Pip %s (%d/%d) is not available, dst wire %s is tied to net %s\n",
                                 getCtx()->nameOfPip(pip), pip.tile, pip.index, getCtx()->nameOfWire(dst),
                                 wire_net->name.c_str(getCtx()));
                    }
#endif
                    // dst is already driven in this net, do not allow!
                    return false;
                } else {
#ifdef DEBUG_BINDING
                    if (getCtx()->verbose && net_iter->second.pip != pip) {
                        log_info("Pip %s (%d/%d) is not available, dst wire %s is tied to net %s\n",
                                 getCtx()->nameOfPip(pip), pip.tile, pip.index, getCtx()->nameOfWire(dst),
                                 wire_net->name.c_str(getCtx()));
                    }
#endif
                    // This pip is available if this pip is already bound to
                    // this.
                    return net_iter->second.pip == pip;
                }
            }
        }
    }

    // If this pip is a route-though, make sure all of the route-though are valid.
    // A route-through is valid if:
    //   - none of the pseudo-pip wires are bound to a net
    //   - the pseudo pip wires are bound to the same net and there are no
    //     lut elements in the tile type: this to prevent the router from choosing
    //     a pseudo-pip on the same LUT and on a different input pin for the same net.
    const TileTypeInfoPOD &tile_type = loc_info(chip_info, pip);
    const PipInfoPOD &pip_data = tile_type.pip_data[pip.index];
    WireId wire;
    wire.tile = pip.tile;
    for (int32_t wire_index : pip_data.pseudo_cell_wires) {
        wire.index = wire_index;
        NPNR_ASSERT(src != wire);
        NPNR_ASSERT(dst != wire);

        NetInfo *other_net = getConflictingWireNet(wire);
        bool is_null_net = other_net == nullptr;
        if (!is_null_net) {
            bool is_same_net = other_net == net;
            bool tile_has_luts = tile_type.lut_elements.size() > 0;
            if (!is_same_net || tile_has_luts) {
#ifdef DEBUG_BINDING
                if (getCtx()->verbose)
                    log_info("Pip %s is not available because wire %s is tied to a different net "
                             "(other net: %s - orig net: %s) or the pseudo pip may traverses LUTs\n",
                             getCtx()->nameOfPip(pip), getCtx()->nameOfWire(wire), other_net->name.c_str(getCtx()),
                             net == nullptr ? "NULL net" : net->name.c_str(getCtx()));
#endif
                return false;
            }
        }
    }

    auto tile_status_iter = tileStatus.find(pip.tile);

    if (pip_data.pseudo_cell_wires.size() > 0) {
        // FIXME: This pseudo pip check is incomplete, because constraint
        // failures will not be detected.  However the current FPGA
        // interchange schema does not provide a cell type to place.
        if (tile_status_iter != tileStatus.end() &&
            !tile_status_iter->second.pseudo_pip_model.checkPipAvail(getCtx(), pip)) {
            return false;
        }
    }

    if (pip_data.site != -1 && net != nullptr) {
        NPNR_ASSERT(net->driver.cell != nullptr);
        NPNR_ASSERT(net->driver.cell->bel != BelId());

        auto &src_wire_data = tile_type.wire_data[pip_data.src_index];
        auto &dst_wire_data = tile_type.wire_data[pip_data.dst_index];

        bool valid_pip = false;
        if (pip.tile == net->driver.cell->bel.tile) {
            if (tile_status_iter == tileStatus.end()) {
                // there is no tile status and nothing blocks the validity of this PIP
                valid_pip = true;
            } else {
                const BelInfoPOD &bel_data = tile_type.bel_data[net->driver.cell->bel.index];
                const SiteRouter &site_router = get_site_status(tile_status_iter->second, bel_data);

                const auto &pips = site_router.valid_pips;
                auto result = std::find(pips.begin(), pips.end(), pip);
                if (result != pips.end()) {
                    valid_pip = true;
                }
            }
        }

        if (disallow_site_routing && !valid_pip) {
            // For now, if driver is not part of this site, and
            // disallow_site_routing is set, disallow the edge.
            return false;
        }

        // FIXME: This check isn't perfect.  If a driver and sink are in the
        // same site, it is possible for the router to route-thru the site
        // ports without hitting a sink, which is not legal in the FPGA
        // interchange.
        if (!valid_pip) {
            // See if one users can enter this site.
            if (dst_wire_data.site == -1) {
                // This is an output site port, but not for the driver net.
                // Disallow.
                NPNR_ASSERT(src_wire_data.site == pip_data.site);
            } else {
                // This might be a valid pip, scan users.
                for (auto &user : net->users) {
                    NPNR_ASSERT(user.cell != nullptr);
                    if (user.cell->bel == BelId()) {
                        continue;
                    }

                    auto &bel_data = bel_info(chip_info, user.cell->bel);
                    if (bel_data.site == pip_data.site) {
                        valid_pip = true;
                        break;
                    }
                }
            }
        }

        if (!valid_pip) {
#ifdef DEBUG_BINDING
            if (getCtx()->verbose) {
                log_info("Pip %s is within a site and not available not right now\n", getCtx()->nameOfPip(pip));
            }
#endif
            return false;
        }
    }

    return true;
}

bool Arch::checkPipAvail(PipId pip) const { return checkPipAvailForNet(pip, nullptr); }

std::string Arch::get_chipdb_hash() const { return chipdb_hash; }

bool Arch::is_inverting(PipId pip) const
{
    auto &tile_type = loc_info(chip_info, pip);
    auto &pip_info = tile_type.pip_data[pip.index];
    if (pip_info.site == -1) {
        // FIXME: Some routing pips are inverters, but this is missing from
        // the chipdb.
        return false;
    }

    auto &bel_data = tile_type.bel_data[pip_info.bel];

    // Is a fixed inverter if the non_inverting_pin is another pin.
    return bel_data.non_inverting_pin != pip_info.extra_data && bel_data.inverting_pin == pip_info.extra_data;
}

bool Arch::can_invert(PipId pip) const
{
    auto &tile_type = loc_info(chip_info, pip);
    auto &pip_info = tile_type.pip_data[pip.index];
    if (pip_info.site == -1) {
        return false;
    }

    auto &bel_data = tile_type.bel_data[pip_info.bel];

    // Can optionally invert if this pip is both the non_inverting_pin and
    // inverting pin.
    return bel_data.non_inverting_pin == pip_info.extra_data && bel_data.inverting_pin == pip_info.extra_data;
}

void Arch::mask_bel_pins_on_site_wire(NetInfo *net, WireId wire)
{
    std::vector<size_t> bel_pins_to_mask;
    for (const PortRef &port_ref : net->users) {
        if (port_ref.cell->bel == BelId()) {
            continue;
        }

        NPNR_ASSERT(port_ref.cell != nullptr);
        auto iter = port_ref.cell->cell_bel_pins.find(port_ref.port);
        if (iter == port_ref.cell->cell_bel_pins.end()) {
            continue;
        }

        std::vector<IdString> &cell_bel_pins = iter->second;
        bel_pins_to_mask.clear();

        for (size_t bel_pin_idx = 0; bel_pin_idx < cell_bel_pins.size(); ++bel_pin_idx) {
            IdString bel_pin = cell_bel_pins.at(bel_pin_idx);
            WireId bel_pin_wire = getBelPinWire(port_ref.cell->bel, bel_pin);
            if (bel_pin_wire == wire) {
                bel_pins_to_mask.push_back(bel_pin_idx);
            }
        }

        if (!bel_pins_to_mask.empty()) {
            std::vector<IdString> &masked_cell_bel_pins = port_ref.cell->masked_cell_bel_pins[port_ref.port];
            // Remove in reverse order to preserve indicies.
            for (auto riter = bel_pins_to_mask.rbegin(); riter != bel_pins_to_mask.rend(); ++riter) {
                size_t bel_pin_idx = *riter;
                masked_cell_bel_pins.push_back(cell_bel_pins.at(bel_pin_idx));
                cell_bel_pins.erase(cell_bel_pins.begin() + bel_pin_idx);
            }
        }
    }
}

void Arch::unmask_bel_pins()
{
    for (auto &cell_pair : cells) {
        CellInfo *cell = cell_pair.second.get();
        if (cell->masked_cell_bel_pins.empty()) {
            continue;
        }

        for (auto &mask_pair : cell->masked_cell_bel_pins) {
            IdString cell_port = mask_pair.first;
            const std::vector<IdString> &bel_pins = mask_pair.second;
            std::vector<IdString> &cell_bel_pins = cell->cell_bel_pins[cell_port];
            cell_bel_pins.insert(cell_bel_pins.begin(), bel_pins.begin(), bel_pins.end());
        }

        cell->masked_cell_bel_pins.clear();
    }
}

void Arch::remove_site_routing()
{
    pool<WireId> wires_to_unbind;
    for (auto &net_pair : nets) {
        for (auto &wire_pair : net_pair.second->wires) {
            WireId wire = wire_pair.first;
            if (wire_pair.second.strength != STRENGTH_PLACER) {
                // Only looking for bound placer wires
                continue;
            }
            wires_to_unbind.emplace(wire);
        }
    }

    for (WireId wire : wires_to_unbind) {
        unbindWire(wire);
    }

    unmask_bel_pins();

    IdString id_NEXTPNR_INV = id("$nextpnr_inv");
    IdString id_I = id("I");
    std::vector<IdString> cells_to_remove;
    for (auto &cell_pair : cells) {
        CellInfo *cell = cell_pair.second.get();
        if (cell->type != id_NEXTPNR_INV) {
            continue;
        }

        disconnectPort(cell_pair.first, id_I);
        cells_to_remove.push_back(cell_pair.first);
        tileStatus.at(cell->bel.tile).boundcells[cell->bel.index] = nullptr;
    }

    for (IdString cell_name : cells_to_remove) {
        NPNR_ASSERT(cells.erase(cell_name) == 1);
    }
}

void Arch::explain_bel_status(BelId bel) const
{
    if (isBelLocationValid(bel)) {
        log_info("BEL %s is valid!\n", nameOfBel(bel));
        return;
    }

    auto iter = tileStatus.find(bel.tile);
    NPNR_ASSERT(iter != tileStatus.end());
    const TileStatus &tile_status = iter->second;
    const CellInfo *cell = tile_status.boundcells[bel.index];
    if (!dedicated_interconnect.isBelLocationValid(bel, cell)) {
        dedicated_interconnect.explain_bel_status(bel, cell);
        return;
    }

    if (io_port_types.count(cell->type)) {
        return;
    }

    if (!is_cell_valid_constraints(cell, tile_status, /*explain_constraints=*/true)) {
        return;
    }

    auto &bel_data = bel_info(chip_info, bel);
    const SiteRouter &site = get_site_status(tile_status, bel_data);
    NPNR_ASSERT(!site.checkSiteRouting(getCtx(), tile_status));
    site.explain(getCtx());
}

DelayQuad Arch::getPipDelay(PipId pip) const
{
    // FIXME: Implement when adding timing-driven place and route.
    const auto &pip_data = pip_info(chip_info, pip);

    // Scale pseudo-pips by the number of wires they consume to make them
    // more expensive than a single edge.  This approximation exists soley to
    // make the non-timing driven solution avoid thinking that pseudo-pips
    // are the same cost as regular pips.
    return DelayQuad(100 * (1 + pip_data.pseudo_cell_wires.size()));
}

const DefaultCellConnsPOD *Arch::get_default_conns(IdString cell_type) const
{
    for (const auto &conn : chip_info->constants->default_conns) {
        if (IdString(conn.cell_type) == cell_type)
            return &conn;
    }
    return nullptr;
}

void Arch::pack_default_conns()
{
    IdString vcc_net_name(chip_info->constants->vcc_net_name);
    IdString gnd_net_name(chip_info->constants->gnd_net_name);
    Context *ctx = getCtx();

    std::vector<IdString> dead_nets;

    for (auto &cell : ctx->cells) {
        CellInfo *ci = cell.second.get();
        const DefaultCellConnsPOD *conns = get_default_conns(ci->type);
        if (conns == nullptr)
            continue;
        for (const auto &pin : conns->pins) {
            IdString pin_name(pin.pin_name);
            // pin missing, create it
            if (!ci->ports.count(pin_name))
                ci->addInput(pin_name);
            const NetInfo *net = ci->ports.at(pin_name).net;
            if (net != nullptr) {
                // pin is connected, and driven, nothing to do
                if (net->driver.cell != nullptr)
                    continue;
                // pin is connected but undriven, disconnect the existing net
                ctx->disconnectPort(ci->name, pin_name);
                // remove net if it has no remaining users
                if (net->users.empty())
                    dead_nets.push_back(net->name);
            }
            if (pin.value == PIN_VALUE_GND)
                ctx->connectPort(gnd_net_name, ci->name, pin_name);
            else if (pin.value == PIN_VALUE_VCC)
                ctx->connectPort(vcc_net_name, ci->name, pin_name);
            else
                NPNR_ASSERT(pin.value == PIN_VALUE_FLOAT);
        }
    }

    // Remove any left-behind nets with no users and no drivers
    for (auto net : dead_nets)
        ctx->nets.erase(net);
}

// Instance constraint templates.
template void Arch::ArchConstraints::bindBel(Arch::ArchConstraints::TagState *, const Arch::ConstraintRange);
template void Arch::ArchConstraints::unbindBel(Arch::ArchConstraints::TagState *, const Arch::ConstraintRange);
template bool Arch::ArchConstraints::isValidBelForCellType(const Context *, uint32_t,
                                                           const Arch::ArchConstraints::TagState *,
                                                           const Arch::ConstraintRange, IdString, IdString, BelId,
                                                           bool) const;

NEXTPNR_NAMESPACE_END