nextpnr/common/router2.cc

/*
 *  nextpnr -- Next Generation Place and Route
 *
 *  Copyright (C) 2019  David Shah <dave@ds0.me>
 *
 *  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 <algorithm>
#include <deque>
#include <queue>
#include "log.h"
#include "nextpnr.h"
#include "util.h"

NEXTPNR_NAMESPACE_BEGIN

namespace {
struct Router2
{
    struct arc_key
    {
        NetInfo *net_info;
        int user_idx;

        bool operator==(const arc_key &other) const
        {
            return (net_info == other.net_info) && (user_idx == other.user_idx);
        }
        bool operator<(const arc_key &other) const
        {
            return net_info == other.net_info ? user_idx < other.user_idx : net_info->name < other.net_info->name;
        }

        struct Hash
        {
            std::size_t operator()(const arc_key &arg) const noexcept
            {
                std::size_t seed = std::hash<NetInfo *>()(arg.net_info);
                seed ^= std::hash<int>()(arg.user_idx) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
                return seed;
            }
        };
    };

    struct arc_entry
    {
        arc_key arc;
        delay_t pri;
        int randtag = 0;

        struct Less
        {
            bool operator()(const arc_entry &lhs, const arc_entry &rhs) const noexcept
            {
                if (lhs.pri != rhs.pri)
                    return lhs.pri < rhs.pri;
                return lhs.randtag < rhs.randtag;
            }
        };
    };

    struct BoundingBox
    {
        int x0, x1, y0, y1;
    };

    struct PerArcData
    {
        std::vector<std::pair<WireId, PipId>> wires;
        BoundingBox bb;
    };

    // As we allow overlap at first; the nextpnr bind functions can't be used
    // as the primary relation between arcs and wires/pips
    struct PerNetData
    {
        std::vector<PerArcData> arcs;
        BoundingBox bb;
    };

    struct PerWireData
    {
        // net --> driving pip
        std::unordered_map<int, PipId> bound_nets;
        // Which net is bound in the Arch API
        int arch_bound_net = -1;
        // Historical congestion cost
        float hist_cong_cost = 0;
    };

    struct WireScore
    {
        float cost;
        float togo_cost;
        delay_t delay;
        float total() const { return cost + togo_cost; }
    };

    Context *ctx;

    // Use 'udata' for fast net lookups and indexing
    std::vector<NetInfo *> nets_by_udata;

    struct QueuedWire
    {

        explicit QueuedWire(WireId wire = WireId(), PipId pip = PipId(), WireScore score = WireScore{}, int randtag = 0)
                : wire(wire), pip(pip), score(score), randtag(randtag){};

        WireId wire;
        PipId pip;

        WireScore score;
        int randtag = 0;

        struct Greater
        {
            bool operator()(const QueuedWire &lhs, const QueuedWire &rhs) const noexcept
            {
                float lhs_score = lhs.score.cost + lhs.score.togo_cost,
                      rhs_score = rhs.score.cost + rhs.score.togo_cost;
                return lhs_score == rhs_score ? lhs.randtag > rhs.randtag : lhs_score > rhs_score;
            }
        };
    };

    double curr_cong_weight, hist_cong_weight, estimate_weight;
    // Soft-route a net (don't touch Arch data structures which might not be thread safe)
    // If is_mt is true, then strict bounding box rules are applied and log_* won't be called
    struct ThreadContext
    {
        std::priority_queue<QueuedWire, std::vector<QueuedWire>, QueuedWire::Greater> queue;
        std::unordered_map<WireId, QueuedWire> visited;
    };

    enum ArcRouteResult
    {
        ARC_SUCCESS,
        ARC_RETRY_WITHOUT_BB,
        ARC_FATAL,
    };

// Avoid log_error in MT
#define ARC_ERR(...)                                                                                                   \
    do {                                                                                                               \
        if (is_mt)                                                                                                     \
            return ARC_FATAL;                                                                                          \
        else                                                                                                           \
            log_error(__VA_ARGS__);                                                                                    \
    } while (0)
#define ARC_DBG(...)                                                                                                   \
    do {                                                                                                               \
        if (!is_mt && ctx->debug)                                                                                      \
            log(__VA_ARGS__);                                                                                          \
    } while (0)

    ArcRouteResult route_arc(ThreadContext &t, NetInfo *net, size_t i, bool is_mt, bool is_bb = true)
    {
        auto &usr = net->users.at(i);
        ARC_DBG("Routing arc %d of net '%s'", int(i), ctx->nameOf(net));
        WireId src_wire = ctx->getNetinfoSourceWire(net), dst_wire = ctx->getNetinfoSinkWire(net, usr);

        if (src_wire == WireId())
            log_error("No wire found for port %s on source cell %s.\n", ctx->nameOf(net->driver.port),
                      ctx->nameOf(net->driver.cell));
        if (dst_wire == WireId())
            log_error("No wire found for port %s on destination cell %s.\n", ctx->nameOf(usr.port),
                      ctx->nameOf(usr.cell));
    }
#undef ARC_ERR
#undef ARC_DBG
    bool route_net(ThreadContext &t, NetInfo *net, bool is_mt)
    {

        // Define to make sure we don't print in a multithreaded context

        if (!t.queue.empty()) {
            std::priority_queue<QueuedWire, std::vector<QueuedWire>, QueuedWire::Greater> new_queue;
            t.queue.swap(new_queue);
        }
        t.visited.clear();
        for (size_t i = 0; i < net->users.size(); i++) {
        }
    }

    void bind_and_check_legality(NetInfo *net) {}
};
} // namespace

NEXTPNR_NAMESPACE_END