Split up common into kernel,place,route

Signed-off-by: gatecat <gatecat@ds0.me>

4 files changed, 2785 insertions, 0 deletions

diff --git a/common/route/router1.cc b/common/route/router1.cc
new file mode 100644
index 00000000..98132116
--- /dev/null
+++ b/common/route/router1.cc
@@ -0,0 +1,1175 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2018  Claire Xenia Wolf <claire@yosyshq.com>
+ *
+ *  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 <chrono>
+#include <cmath>
+#include <queue>
+
+#include "log.h"
+#include "router1.h"
+#include "scope_lock.h"
+#include "timing.h"
+
+namespace {
+
+USING_NEXTPNR_NAMESPACE
+
+struct arc_key
+{
+    NetInfo *net_info;
+    // logical user cell port index
+    store_index<PortRef> user_idx;
+    // physical index into cell->bel pin mapping (usually 0)
+    unsigned phys_idx;
+
+    bool operator==(const arc_key &other) const
+    {
+        return (net_info == other.net_info) && (user_idx == other.user_idx) && (phys_idx == other.phys_idx);
+    }
+    bool operator<(const arc_key &other) const
+    {
+        return net_info == other.net_info
+                       ? (user_idx == other.user_idx ? phys_idx < other.phys_idx : user_idx < other.user_idx)
+                       : net_info->name < other.net_info->name;
+    }
+
+    unsigned int hash() const
+    {
+        std::size_t seed = std::hash<NetInfo *>()(net_info);
+        seed ^= user_idx.hash() + 0x9e3779b9 + (seed << 6) + (seed >> 2);
+        seed ^= std::hash<int>()(phys_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 QueuedWire
+{
+    WireId wire;
+    PipId pip;
+
+    delay_t delay = 0, penalty = 0, bonus = 0, togo = 0;
+    int randtag = 0;
+
+    struct Greater
+    {
+        bool operator()(const QueuedWire &lhs, const QueuedWire &rhs) const noexcept
+        {
+            delay_t l = lhs.delay + lhs.penalty + lhs.togo;
+            delay_t r = rhs.delay + rhs.penalty + rhs.togo;
+            NPNR_ASSERT(l >= 0);
+            NPNR_ASSERT(r >= 0);
+            l -= lhs.bonus;
+            r -= rhs.bonus;
+            return l == r ? lhs.randtag > rhs.randtag : l > r;
+        }
+    };
+};
+
+struct Router1
+{
+    Context *ctx;
+    const Router1Cfg &cfg;
+
+    std::priority_queue<arc_entry, std::vector<arc_entry>, arc_entry::Less> arc_queue;
+    dict<WireId, pool<arc_key>> wire_to_arcs;
+    dict<arc_key, pool<WireId>> arc_to_wires;
+    pool<arc_key> queued_arcs;
+
+    std::priority_queue<QueuedWire, std::vector<QueuedWire>, QueuedWire::Greater> queue;
+
+    dict<WireId, int> wireScores;
+    dict<NetInfo *, int, hash_ptr_ops> netScores;
+
+    int arcs_with_ripup = 0;
+    int arcs_without_ripup = 0;
+    bool ripup_flag;
+
+    TimingAnalyser tmg;
+
+    bool timing_driven = true;
+
+    Router1(Context *ctx, const Router1Cfg &cfg) : ctx(ctx), cfg(cfg), tmg(ctx)
+    {
+        timing_driven = ctx->setting<bool>("timing_driven");
+        tmg.setup();
+        tmg.run();
+    }
+
+    void arc_queue_insert(const arc_key &arc, WireId src_wire, WireId dst_wire)
+    {
+        if (queued_arcs.count(arc))
+            return;
+
+        delay_t pri = ctx->estimateDelay(src_wire, dst_wire) *
+                      (100 * tmg.get_criticality(CellPortKey(arc.net_info->users.at(arc.user_idx))));
+
+        arc_entry entry;
+        entry.arc = arc;
+        entry.pri = pri;
+        entry.randtag = ctx->rng();
+
+#if 0
+        if (ctx->debug)
+            log("[arc_queue_insert] %s (%d) %s %s [%d %d]\n", ctx->nameOf(entry.arc.net_info), entry.arc.user_idx,
+                ctx->nameOfWire(src_wire), ctx->nameOfWire(dst_wire), (int)entry.pri, entry.randtag);
+#endif
+
+        arc_queue.push(entry);
+        queued_arcs.insert(arc);
+    }
+
+    void arc_queue_insert(const arc_key &arc)
+    {
+        if (queued_arcs.count(arc))
+            return;
+
+        NetInfo *net_info = arc.net_info;
+        auto user_idx = arc.user_idx;
+        unsigned phys_idx = arc.phys_idx;
+
+        auto src_wire = ctx->getNetinfoSourceWire(net_info);
+        auto dst_wire = ctx->getNetinfoSinkWire(net_info, net_info->users[user_idx], phys_idx);
+
+        arc_queue_insert(arc, src_wire, dst_wire);
+    }
+
+    arc_key arc_queue_pop()
+    {
+        arc_entry entry = arc_queue.top();
+
+#if 0
+        if (ctx->debug)
+            log("[arc_queue_pop] %s (%d) [%d %d]\n", ctx->nameOf(entry.arc.net_info), entry.arc.user_idx,
+                (int)entry.pri, entry.randtag);
+#endif
+
+        arc_queue.pop();
+        queued_arcs.erase(entry.arc);
+        return entry.arc;
+    }
+
+    void ripup_net(NetInfo *net)
+    {
+        if (ctx->debug)
+            log("      ripup net %s\n", ctx->nameOf(net));
+
+        netScores[net]++;
+
+        std::vector<WireId> wires;
+        for (auto &it : net->wires)
+            wires.push_back(it.first);
+
+        ctx->sorted_shuffle(wires);
+
+        for (WireId w : wires) {
+            std::vector<arc_key> arcs;
+            for (auto &it : wire_to_arcs[w]) {
+                arc_to_wires[it].erase(w);
+                arcs.push_back(it);
+            }
+            wire_to_arcs[w].clear();
+
+            ctx->sorted_shuffle(arcs);
+
+            for (auto &it : arcs)
+                arc_queue_insert(it);
+
+            if (ctx->debug)
+                log("        unbind wire %s\n", ctx->nameOfWire(w));
+
+            ctx->unbindWire(w);
+            wireScores[w]++;
+        }
+
+        ripup_flag = true;
+    }
+
+    void ripup_wire(WireId wire, int extra_indent = 0)
+    {
+        if (ctx->debug)
+            log("    ripup wire %s\n", ctx->nameOfWire(wire));
+
+        WireId w = ctx->getConflictingWireWire(wire);
+
+        if (w == WireId()) {
+            NetInfo *n = ctx->getConflictingWireNet(wire);
+            if (n != nullptr)
+                ripup_net(n);
+        } else {
+            std::vector<arc_key> arcs;
+            for (auto &it : wire_to_arcs[w]) {
+                arc_to_wires[it].erase(w);
+                arcs.push_back(it);
+            }
+            wire_to_arcs[w].clear();
+
+            ctx->sorted_shuffle(arcs);
+
+            for (auto &it : arcs)
+                arc_queue_insert(it);
+
+            if (ctx->debug)
+                log("      unbind wire %s\n", ctx->nameOfWire(w));
+
+            ctx->unbindWire(w);
+            wireScores[w]++;
+        }
+
+        ripup_flag = true;
+    }
+
+    void ripup_pip(PipId pip)
+    {
+        if (ctx->debug)
+            log("    ripup pip %s\n", ctx->nameOfPip(pip));
+
+        WireId w = ctx->getConflictingPipWire(pip);
+
+        if (w == WireId()) {
+            NetInfo *n = ctx->getConflictingPipNet(pip);
+            if (n != nullptr)
+                ripup_net(n);
+        } else {
+            std::vector<arc_key> arcs;
+            for (auto &it : wire_to_arcs[w]) {
+                arc_to_wires[it].erase(w);
+                arcs.push_back(it);
+            }
+            wire_to_arcs[w].clear();
+
+            ctx->sorted_shuffle(arcs);
+
+            for (auto &it : arcs)
+                arc_queue_insert(it);
+
+            if (ctx->debug)
+                log("      unbind wire %s\n", ctx->nameOfWire(w));
+
+            ctx->unbindWire(w);
+            wireScores[w]++;
+        }
+
+        ripup_flag = true;
+    }
+
+    bool skip_net(NetInfo *net_info)
+    {
+#ifdef ARCH_ECP5
+        // ECP5 global nets currently appear part-unrouted due to arch database limitations
+        // Don't touch them in the router
+        if (net_info->is_global)
+            return true;
+#endif
+        if (net_info->driver.cell == nullptr)
+            return true;
+
+        return false;
+    }
+
+    void check()
+    {
+        pool<arc_key> valid_arcs;
+
+        for (auto &net_it : ctx->nets) {
+            NetInfo *net_info = net_it.second.get();
+            pool<WireId> valid_wires_for_net;
+
+            if (skip_net(net_info))
+                continue;
+
+#if 0
+            if (ctx->debug)
+                log("[check] net: %s\n", ctx->nameOf(net_info));
+#endif
+
+            auto src_wire = ctx->getNetinfoSourceWire(net_info);
+            log_assert(src_wire != WireId());
+
+            for (auto user : net_info->users.enumerate()) {
+                unsigned phys_idx = 0;
+                for (auto dst_wire : ctx->getNetinfoSinkWires(net_info, user.value)) {
+                    log_assert(dst_wire != WireId());
+
+                    arc_key arc;
+                    arc.net_info = net_info;
+                    arc.user_idx = user.index;
+                    arc.phys_idx = phys_idx++;
+                    valid_arcs.insert(arc);
+#if 0
+                    if (ctx->debug)
+                    log("[check]   arc: %s %s\n", ctx->nameOfWire(src_wire), ctx->nameOfWire(dst_wire));
+#endif
+
+                    for (WireId wire : arc_to_wires[arc]) {
+#if 0
+                        if (ctx->debug)
+                        log("[check]     wire: %s\n", ctx->nameOfWire(wire));
+#endif
+                        valid_wires_for_net.insert(wire);
+                        log_assert(wire_to_arcs[wire].count(arc));
+                        log_assert(net_info->wires.count(wire));
+                    }
+                }
+            }
+
+            for (auto &it : net_info->wires) {
+                WireId w = it.first;
+                log_assert(valid_wires_for_net.count(w));
+            }
+        }
+
+        for (auto &it : wire_to_arcs) {
+            for (auto &arc : it.second)
+                log_assert(valid_arcs.count(arc));
+        }
+
+        for (auto &it : arc_to_wires) {
+            log_assert(valid_arcs.count(it.first));
+        }
+    }
+
+    void setup()
+    {
+        dict<WireId, NetInfo *> src_to_net;
+        dict<WireId, arc_key> dst_to_arc;
+
+        std::vector<IdString> net_names;
+        for (auto &net_it : ctx->nets)
+            net_names.push_back(net_it.first);
+
+        ctx->sorted_shuffle(net_names);
+
+        for (IdString net_name : net_names) {
+            NetInfo *net_info = ctx->nets.at(net_name).get();
+
+            if (skip_net(net_info))
+                continue;
+
+            auto src_wire = ctx->getNetinfoSourceWire(net_info);
+
+            if (src_wire == WireId())
+                log_error("No wire found for port %s on source cell %s.\n", ctx->nameOf(net_info->driver.port),
+                          ctx->nameOf(net_info->driver.cell));
+
+            if (src_to_net.count(src_wire))
+                log_error("Found two nets with same source wire %s: %s vs %s\n", ctx->nameOfWire(src_wire),
+                          ctx->nameOf(net_info), ctx->nameOf(src_to_net.at(src_wire)));
+
+            if (dst_to_arc.count(src_wire))
+                log_error("Wire %s is used as source and sink in different nets: %s vs %s (%d)\n",
+                          ctx->nameOfWire(src_wire), ctx->nameOf(net_info),
+                          ctx->nameOf(dst_to_arc.at(src_wire).net_info), dst_to_arc.at(src_wire).user_idx.idx());
+
+            for (auto user : net_info->users.enumerate()) {
+                unsigned phys_idx = 0;
+                for (auto dst_wire : ctx->getNetinfoSinkWires(net_info, user.value)) {
+                    arc_key arc;
+                    arc.net_info = net_info;
+                    arc.user_idx = user.index;
+                    arc.phys_idx = phys_idx++;
+
+                    if (dst_to_arc.count(dst_wire)) {
+                        if (dst_to_arc.at(dst_wire).net_info == net_info)
+                            continue;
+                        log_error("Found two arcs with same sink wire %s: %s (%d) vs %s (%d)\n",
+                                  ctx->nameOfWire(dst_wire), ctx->nameOf(net_info), user.index.idx(),
+                                  ctx->nameOf(dst_to_arc.at(dst_wire).net_info),
+                                  dst_to_arc.at(dst_wire).user_idx.idx());
+                    }
+
+                    if (src_to_net.count(dst_wire))
+                        log_error("Wire %s is used as source and sink in different nets: %s vs %s (%d)\n",
+                                  ctx->nameOfWire(dst_wire), ctx->nameOf(src_to_net.at(dst_wire)),
+                                  ctx->nameOf(net_info), user.index.idx());
+
+                    dst_to_arc[dst_wire] = arc;
+
+                    if (net_info->wires.count(dst_wire) == 0) {
+                        arc_queue_insert(arc, src_wire, dst_wire);
+                        continue;
+                    }
+
+                    WireId cursor = dst_wire;
+                    wire_to_arcs[cursor].insert(arc);
+                    arc_to_wires[arc].insert(cursor);
+
+                    while (src_wire != cursor) {
+                        auto it = net_info->wires.find(cursor);
+                        if (it == net_info->wires.end()) {
+                            arc_queue_insert(arc, src_wire, dst_wire);
+                            break;
+                        }
+
+                        NPNR_ASSERT(it->second.pip != PipId());
+                        cursor = ctx->getPipSrcWire(it->second.pip);
+                        wire_to_arcs[cursor].insert(arc);
+                        arc_to_wires[arc].insert(cursor);
+                    }
+                }
+                // TODO: this matches the situation before supporting multiple cell->bel pins, but do we want to keep
+                // this invariant?
+                if (phys_idx == 0)
+                    log_warning("No wires found for port %s on destination cell %s.\n", ctx->nameOf(user.value.port),
+                                ctx->nameOf(user.value.cell));
+            }
+
+            src_to_net[src_wire] = net_info;
+
+            std::vector<WireId> unbind_wires;
+
+            for (auto &it : net_info->wires)
+                if (it.second.strength < STRENGTH_LOCKED && wire_to_arcs.count(it.first) == 0)
+                    unbind_wires.push_back(it.first);
+
+            for (auto it : unbind_wires)
+                ctx->unbindWire(it);
+        }
+    }
+
+    bool route_arc(const arc_key &arc, bool ripup)
+    {
+
+        NetInfo *net_info = arc.net_info;
+        auto user_idx = arc.user_idx;
+
+        auto src_wire = ctx->getNetinfoSourceWire(net_info);
+        auto dst_wire = ctx->getNetinfoSinkWire(net_info, net_info->users[user_idx], arc.phys_idx);
+        ripup_flag = false;
+
+        float crit = tmg.get_criticality(CellPortKey(net_info->users.at(user_idx)));
+
+        if (ctx->debug) {
+            log("Routing arc %d on net %s (%d arcs total):\n", user_idx.idx(), ctx->nameOf(net_info),
+                int(net_info->users.capacity()));
+            log("  source ... %s\n", ctx->nameOfWire(src_wire));
+            log("  sink ..... %s\n", ctx->nameOfWire(dst_wire));
+        }
+
+        // unbind wires that are currently used exclusively by this arc
+
+        pool<WireId> old_arc_wires;
+        old_arc_wires.swap(arc_to_wires[arc]);
+
+        for (WireId wire : old_arc_wires) {
+            auto &arc_wires = wire_to_arcs.at(wire);
+            NPNR_ASSERT(arc_wires.count(arc));
+            arc_wires.erase(arc);
+            if (arc_wires.empty()) {
+                if (ctx->debug)
+                    log("  unbind %s\n", ctx->nameOfWire(wire));
+                ctx->unbindWire(wire);
+            }
+        }
+
+        // special case
+
+        if (src_wire == dst_wire) {
+            NetInfo *bound = ctx->getBoundWireNet(src_wire);
+            if (bound != nullptr)
+                NPNR_ASSERT(bound == net_info);
+            else {
+                ctx->bindWire(src_wire, net_info, STRENGTH_WEAK);
+            }
+            arc_to_wires[arc].insert(src_wire);
+            wire_to_arcs[src_wire].insert(arc);
+            return true;
+        }
+
+        // reset wire queue
+
+        if (!queue.empty()) {
+            std::priority_queue<QueuedWire, std::vector<QueuedWire>, QueuedWire::Greater> new_queue;
+            queue.swap(new_queue);
+        }
+        dict<WireId, QueuedWire> visited;
+
+        // A* main loop
+
+        int visitCnt = 0;
+        int maxVisitCnt = INT_MAX;
+        delay_t best_est = 0;
+        delay_t best_score = -1;
+
+        {
+            QueuedWire qw;
+            qw.wire = src_wire;
+            qw.pip = PipId();
+            qw.delay = ctx->getWireDelay(qw.wire).maxDelay();
+            qw.penalty = 0;
+            qw.bonus = 0;
+            if (cfg.useEstimate) {
+                qw.togo = ctx->estimateDelay(qw.wire, dst_wire);
+                best_est = qw.delay + qw.togo;
+            }
+            qw.randtag = ctx->rng();
+
+            queue.push(qw);
+            visited[qw.wire] = qw;
+        }
+
+        while (visitCnt++ < maxVisitCnt && !queue.empty()) {
+            QueuedWire qw = queue.top();
+            queue.pop();
+
+            for (auto pip : ctx->getPipsDownhill(qw.wire)) {
+                delay_t next_delay = qw.delay + ctx->getPipDelay(pip).maxDelay();
+                delay_t next_penalty = qw.penalty;
+                delay_t next_bonus = qw.bonus;
+                delay_t penalty_delta = 0;
+
+                WireId next_wire = ctx->getPipDstWire(pip);
+                next_delay += ctx->getWireDelay(next_wire).maxDelay();
+
+                WireId conflictWireWire = WireId(), conflictPipWire = WireId();
+                NetInfo *conflictWireNet = nullptr, *conflictPipNet = nullptr;
+
+                if (net_info->wires.count(next_wire) && net_info->wires.at(next_wire).pip == pip) {
+                    next_bonus += cfg.reuseBonus * (1.0 - crit);
+                } else {
+                    if (!ctx->checkWireAvail(next_wire)) {
+                        if (!ripup)
+                            continue;
+                        conflictWireWire = ctx->getConflictingWireWire(next_wire);
+                        if (conflictWireWire == WireId()) {
+                            conflictWireNet = ctx->getConflictingWireNet(next_wire);
+                            if (conflictWireNet == nullptr)
+                                continue;
+                            else {
+                                if (conflictWireNet->wires.count(next_wire) &&
+                                    conflictWireNet->wires.at(next_wire).strength > STRENGTH_STRONG)
+                                    continue;
+                            }
+                        } else {
+                            NetInfo *conflicting = ctx->getBoundWireNet(conflictWireWire);
+                            if (conflicting != nullptr) {
+                                if (conflicting->wires.count(conflictWireWire) &&
+                                    conflicting->wires.at(conflictWireWire).strength > STRENGTH_STRONG)
+                                    continue;
+                            }
+                        }
+                    }
+
+                    if (!ctx->checkPipAvail(pip)) {
+                        if (!ripup)
+                            continue;
+                        conflictPipWire = ctx->getConflictingPipWire(pip);
+                        if (conflictPipWire == WireId()) {
+                            conflictPipNet = ctx->getConflictingPipNet(pip);
+                            if (conflictPipNet == nullptr)
+                                continue;
+                            else {
+                                if (conflictPipNet->wires.count(next_wire) &&
+                                    conflictPipNet->wires.at(next_wire).strength > STRENGTH_STRONG)
+                                    continue;
+                            }
+                        } else {
+                            NetInfo *conflicting = ctx->getBoundWireNet(conflictPipWire);
+                            if (conflicting != nullptr) {
+                                if (conflicting->wires.count(conflictPipWire) &&
+                                    conflicting->wires.at(conflictPipWire).strength > STRENGTH_STRONG)
+                                    continue;
+                            }
+                        }
+                    }
+
+                    if (conflictWireNet != nullptr && conflictPipWire != WireId() &&
+                        conflictWireNet->wires.count(conflictPipWire))
+                        conflictPipWire = WireId();
+
+                    if (conflictPipNet != nullptr && conflictWireWire != WireId() &&
+                        conflictPipNet->wires.count(conflictWireWire))
+                        conflictWireWire = WireId();
+
+                    if (conflictWireWire == conflictPipWire)
+                        conflictWireWire = WireId();
+
+                    if (conflictWireNet == conflictPipNet)
+                        conflictWireNet = nullptr;
+
+                    if (conflictWireWire != WireId()) {
+                        auto scores_it = wireScores.find(conflictWireWire);
+                        if (scores_it != wireScores.end())
+                            penalty_delta += scores_it->second * cfg.wireRipupPenalty;
+                        penalty_delta += cfg.wireRipupPenalty;
+                    }
+
+                    if (conflictPipWire != WireId()) {
+                        auto scores_it = wireScores.find(conflictPipWire);
+                        if (scores_it != wireScores.end())
+                            penalty_delta += scores_it->second * cfg.wireRipupPenalty;
+                        penalty_delta += cfg.wireRipupPenalty;
+                    }
+
+                    if (conflictWireNet != nullptr) {
+                        auto scores_it = netScores.find(conflictWireNet);
+                        if (scores_it != netScores.end())
+                            penalty_delta += scores_it->second * cfg.netRipupPenalty;
+                        penalty_delta += cfg.netRipupPenalty;
+                        penalty_delta += conflictWireNet->wires.size() * cfg.wireRipupPenalty;
+                    }
+
+                    if (conflictPipNet != nullptr) {
+                        auto scores_it = netScores.find(conflictPipNet);
+                        if (scores_it != netScores.end())
+                            penalty_delta += scores_it->second * cfg.netRipupPenalty;
+                        penalty_delta += cfg.netRipupPenalty;
+                        penalty_delta += conflictPipNet->wires.size() * cfg.wireRipupPenalty;
+                    }
+                }
+
+                next_penalty += penalty_delta * (timing_driven ? std::max(0.05, (1.0 - crit)) : 1);
+
+                delay_t next_score = next_delay + next_penalty;
+                NPNR_ASSERT(next_score >= 0);
+
+                if ((best_score >= 0) && (next_score - next_bonus - cfg.estimatePrecision > best_score))
+                    continue;
+
+                auto old_visited_it = visited.find(next_wire);
+                if (old_visited_it != visited.end()) {
+                    delay_t old_delay = old_visited_it->second.delay;
+                    delay_t old_score = old_delay + old_visited_it->second.penalty;
+                    NPNR_ASSERT(old_score >= 0);
+
+                    if (next_score + ctx->getDelayEpsilon() >= old_score)
+                        continue;
+
+#if 0
+                    if (ctx->debug)
+                        log("Found better route to %s. Old vs new delay estimate: %.3f (%.3f) %.3f (%.3f)\n",
+                            ctx->nameOfWire(next_wire),
+                            ctx->getDelayNS(old_score),
+                            ctx->getDelayNS(old_visited_it->second.delay),
+                            ctx->getDelayNS(next_score),
+                            ctx->getDelayNS(next_delay));
+#endif
+                }
+
+                QueuedWire next_qw;
+                next_qw.wire = next_wire;
+                next_qw.pip = pip;
+                next_qw.delay = next_delay;
+                next_qw.penalty = next_penalty;
+                next_qw.bonus = next_bonus;
+                if (cfg.useEstimate) {
+                    next_qw.togo = ctx->estimateDelay(next_wire, dst_wire);
+                    delay_t this_est = next_qw.delay + next_qw.togo;
+                    if (this_est / 2 - cfg.estimatePrecision > best_est)
+                        continue;
+                    if (best_est > this_est)
+                        best_est = this_est;
+                }
+                next_qw.randtag = ctx->rng();
+
+#if 0
+                if (ctx->debug)
+                    log("%s -> %s: %.3f (%.3f)\n",
+                        ctx->nameOfWire(qw.wire),
+                        ctx->nameOfWire(next_wire),
+                        ctx->getDelayNS(next_score),
+                        ctx->getDelayNS(next_delay));
+#endif
+
+                visited[next_qw.wire] = next_qw;
+                queue.push(next_qw);
+
+                if (next_wire == dst_wire) {
+                    maxVisitCnt = std::min(maxVisitCnt, 2 * visitCnt + (next_qw.penalty > 0 ? 100 : 0));
+                    best_score = next_score - next_bonus;
+                }
+            }
+        }
+
+        if (ctx->debug)
+            log("  total number of visited nodes: %d\n", visitCnt);
+
+        if (visited.count(dst_wire) == 0) {
+            if (ctx->debug)
+                log("  no route found for this arc\n");
+            return false;
+        }
+
+        if (ctx->debug) {
+            log("  final route delay:   %8.2f\n", ctx->getDelayNS(visited[dst_wire].delay));
+            log("  final route penalty: %8.2f\n", ctx->getDelayNS(visited[dst_wire].penalty));
+            log("  final route bonus:   %8.2f\n", ctx->getDelayNS(visited[dst_wire].bonus));
+            log("  arc budget:      %12.2f\n", ctx->getDelayNS(net_info->users[user_idx].budget));
+        }
+
+        // bind resulting route (and maybe unroute other nets)
+
+        pool<WireId> unassign_wires = arc_to_wires[arc];
+
+        WireId cursor = dst_wire;
+        delay_t accumulated_path_delay = 0;
+        delay_t last_path_delay_delta = 0;
+        while (1) {
+            auto pip = visited[cursor].pip;
+
+            if (ctx->debug) {
+                delay_t path_delay_delta = ctx->estimateDelay(cursor, dst_wire) - accumulated_path_delay;
+
+                log("  node %s (%+.2f %+.2f)\n", ctx->nameOfWire(cursor), ctx->getDelayNS(path_delay_delta),
+                    ctx->getDelayNS(path_delay_delta - last_path_delay_delta));
+
+                last_path_delay_delta = path_delay_delta;
+
+                if (pip != PipId())
+                    accumulated_path_delay += ctx->getPipDelay(pip).maxDelay();
+                accumulated_path_delay += ctx->getWireDelay(cursor).maxDelay();
+            }
+
+            if (pip == PipId())
+                NPNR_ASSERT(cursor == src_wire);
+
+            if (!net_info->wires.count(cursor) || net_info->wires.at(cursor).pip != pip) {
+                if (!ctx->checkWireAvail(cursor)) {
+                    ripup_wire(cursor);
+                    NPNR_ASSERT(ctx->checkWireAvail(cursor));
+                }
+
+                if (pip != PipId() && !ctx->checkPipAvail(pip)) {
+                    ripup_pip(pip);
+                    NPNR_ASSERT(ctx->checkPipAvail(pip));
+                }
+
+                if (pip == PipId()) {
+                    if (ctx->debug)
+                        log("    bind wire %s\n", ctx->nameOfWire(cursor));
+                    ctx->bindWire(cursor, net_info, STRENGTH_WEAK);
+                } else {
+                    if (ctx->debug)
+                        log("    bind pip %s\n", ctx->nameOfPip(pip));
+                    ctx->bindPip(pip, net_info, STRENGTH_WEAK);
+                }
+            }
+
+            wire_to_arcs[cursor].insert(arc);
+            arc_to_wires[arc].insert(cursor);
+
+            if (pip == PipId())
+                break;
+
+            cursor = ctx->getPipSrcWire(pip);
+        }
+
+        if (ripup_flag)
+            arcs_with_ripup++;
+        else
+            arcs_without_ripup++;
+
+        return true;
+    }
+
+    delay_t find_slack_thresh()
+    {
+        // If more than 5% of arcs have negative slack; use the 5% threshold as a ripup criteria
+        int arc_count = 0;
+        int failed_count = 0;
+        delay_t default_thresh = ctx->getDelayEpsilon();
+
+        for (auto &net : ctx->nets) {
+            NetInfo *ni = net.second.get();
+            if (skip_net(ni))
+                continue;
+            for (auto &usr : ni->users) {
+                ++arc_count;
+                delay_t slack = tmg.get_setup_slack(CellPortKey(usr));
+                if (slack == std::numeric_limits<delay_t>::min())
+                    continue;
+                if (slack < default_thresh)
+                    ++failed_count;
+            }
+        }
+
+        if (arc_count < 50 || (failed_count < (0.05 * arc_count))) {
+            return default_thresh;
+        }
+
+        std::vector<delay_t> slacks;
+        for (auto &net : ctx->nets) {
+            NetInfo *ni = net.second.get();
+            if (skip_net(ni))
+                continue;
+            for (auto &usr : ni->users) {
+                delay_t slack = tmg.get_setup_slack(CellPortKey(usr));
+                if (slack == std::numeric_limits<delay_t>::min())
+                    continue;
+                slacks.push_back(slack);
+            }
+        }
+        std::sort(slacks.begin(), slacks.end());
+        delay_t thresh = slacks.at(int(slacks.size() * 0.05));
+        log_warning("%.f%% of arcs have failing slack; using %.2fns as ripup threshold. Consider a reduced Fmax "
+                    "constraint.\n",
+                    (100.0 * failed_count) / arc_count, ctx->getDelayNS(thresh));
+        return thresh;
+    }
+};
+
+} // namespace
+
+NEXTPNR_NAMESPACE_BEGIN
+
+Router1Cfg::Router1Cfg(Context *ctx)
+{
+    maxIterCnt = ctx->setting<int>("router1/maxIterCnt", 200);
+    cleanupReroute = ctx->setting<bool>("router1/cleanupReroute", true);
+    fullCleanupReroute = ctx->setting<bool>("router1/fullCleanupReroute", true);
+    useEstimate = ctx->setting<bool>("router1/useEstimate", true);
+
+    wireRipupPenalty = ctx->getRipupDelayPenalty();
+    netRipupPenalty = 10 * ctx->getRipupDelayPenalty();
+    reuseBonus = wireRipupPenalty / 2;
+
+    estimatePrecision = 100 * ctx->getRipupDelayPenalty();
+}
+
+bool router1(Context *ctx, const Router1Cfg &cfg)
+{
+    try {
+        log_break();
+        log_info("Routing..\n");
+        ScopeLock<Context> lock(ctx);
+        auto rstart = std::chrono::high_resolution_clock::now();
+
+        log_info("Setting up routing queue.\n");
+
+        Router1 router(ctx, cfg);
+        router.setup();
+#ifndef NDEBUG
+        router.check();
+#endif
+
+        log_info("Routing %d arcs.\n", int(router.arc_queue.size()));
+
+        int iter_cnt = 0;
+        int last_arcs_with_ripup = 0;
+        int last_arcs_without_ripup = 0;
+        int timing_fail_count = 0;
+        bool timing_ripup = ctx->setting<bool>("router/tmg_ripup", false);
+        delay_t ripup_slack = 0;
+
+        log_info("           |   (re-)routed arcs  |   delta    | remaining|       time spent     |\n");
+        log_info("   IterCnt |  w/ripup   wo/ripup |  w/r  wo/r |      arcs| batch(sec) total(sec)|\n");
+
+        auto prev_time = rstart;
+        while (!router.arc_queue.empty()) {
+            if (++iter_cnt % 1000 == 0) {
+                auto curr_time = std::chrono::high_resolution_clock::now();
+                log_info("%10d | %8d %10d | %4d %5d | %9d| %10.02f %10.02f|\n", iter_cnt, router.arcs_with_ripup,
+                         router.arcs_without_ripup, router.arcs_with_ripup - last_arcs_with_ripup,
+                         router.arcs_without_ripup - last_arcs_without_ripup, int(router.arc_queue.size()),
+                         std::chrono::duration<float>(curr_time - prev_time).count(),
+                         std::chrono::duration<float>(curr_time - rstart).count());
+                prev_time = curr_time;
+                last_arcs_with_ripup = router.arcs_with_ripup;
+                last_arcs_without_ripup = router.arcs_without_ripup;
+                ctx->yield();
+#ifndef NDEBUG
+                router.check();
+#endif
+            }
+
+            if (ctx->debug)
+                log("-- %d --\n", iter_cnt);
+
+            arc_key arc = router.arc_queue_pop();
+
+            if (!router.route_arc(arc, true)) {
+                log_warning("Failed to find a route for arc %d of net %s.\n", arc.user_idx.idx(),
+                            ctx->nameOf(arc.net_info));
+#ifndef NDEBUG
+                router.check();
+                ctx->check();
+#endif
+                return false;
+            }
+            // Timing driven ripup
+            if (timing_ripup && router.arc_queue.empty() && timing_fail_count < 50) {
+                ++timing_fail_count;
+                router.tmg.run();
+                delay_t wns = 0, tns = 0;
+                if (timing_fail_count == 1)
+                    ripup_slack = router.find_slack_thresh();
+                for (auto &net : ctx->nets) {
+                    NetInfo *ni = net.second.get();
+                    if (router.skip_net(ni))
+                        continue;
+                    bool is_locked = false;
+                    for (auto &wire : ni->wires) {
+                        if (wire.second.strength > STRENGTH_STRONG)
+                            is_locked = true;
+                    }
+                    if (is_locked)
+                        continue;
+                    for (auto &usr : ni->users) {
+                        delay_t slack = router.tmg.get_setup_slack(CellPortKey(usr));
+                        if (slack == std::numeric_limits<delay_t>::min())
+                            continue;
+                        if (slack < 0) {
+                            wns = std::min(wns, slack);
+                            tns += slack;
+                        }
+                        if (slack <= ripup_slack) {
+                            for (WireId w : ctx->getNetinfoSinkWires(ni, usr)) {
+                                if (ctx->checkWireAvail(w))
+                                    continue;
+                                router.ripup_wire(w);
+                            }
+                        }
+                    }
+                }
+                log_info("    %d arcs ripped up due to negative slack WNS=%.02fns TNS=%.02fns.\n",
+                         int(router.arc_queue.size()), ctx->getDelayNS(wns), ctx->getDelayNS(tns));
+                iter_cnt = 0;
+                router.wireScores.clear();
+                router.netScores.clear();
+            }
+        }
+        auto rend = std::chrono::high_resolution_clock::now();
+        log_info("%10d | %8d %10d | %4d %5d | %9d| %10.02f %10.02f|\n", iter_cnt, router.arcs_with_ripup,
+                 router.arcs_without_ripup, router.arcs_with_ripup - last_arcs_with_ripup,
+                 router.arcs_without_ripup - last_arcs_without_ripup, int(router.arc_queue.size()),
+                 std::chrono::duration<float>(rend - prev_time).count(),
+                 std::chrono::duration<float>(rend - rstart).count());
+        log_info("Routing complete.\n");
+        ctx->yield();
+        log_info("Router1 time %.02fs\n", std::chrono::duration<float>(rend - rstart).count());
+
+#ifndef NDEBUG
+        router.check();
+        ctx->check();
+        log_assert(ctx->checkRoutedDesign());
+#endif
+
+        log_info("Checksum: 0x%08x\n", ctx->checksum());
+        timing_analysis(ctx, true /* slack_histogram */, true /* print_fmax */, true /* print_path */,
+                        true /* warn_on_failure */, true /* update_results */);
+
+        return true;
+    } catch (log_execution_error_exception) {
+#ifndef NDEBUG
+        ctx->lock();
+        ctx->check();
+        ctx->unlock();
+#endif
+        return false;
+    }
+}
+
+bool Context::checkRoutedDesign() const
+{
+    const Context *ctx = getCtx();
+
+    for (auto &net_it : ctx->nets) {
+        NetInfo *net_info = net_it.second.get();
+
+#ifdef ARCH_ECP5
+        if (net_info->is_global)
+            continue;
+#endif
+
+        if (ctx->debug)
+            log("checking net %s\n", ctx->nameOf(net_info));
+
+        if (net_info->users.empty()) {
+            if (ctx->debug)
+                log("  net without sinks\n");
+            log_assert(net_info->wires.empty());
+            continue;
+        }
+
+        bool found_unrouted = false;
+        bool found_loop = false;
+        bool found_stub = false;
+
+        struct ExtraWireInfo
+        {
+            int order_num = 0;
+            pool<WireId> children;
+        };
+
+        dict<WireId, std::unique_ptr<ExtraWireInfo>> db;
+
+        for (auto &it : net_info->wires) {
+            WireId w = it.first;
+            PipId p = it.second.pip;
+
+            if (p != PipId()) {
+                log_assert(ctx->getPipDstWire(p) == w);
+                db.emplace(ctx->getPipSrcWire(p), std::make_unique<ExtraWireInfo>()).first->second->children.insert(w);
+            }
+        }
+
+        auto src_wire = ctx->getNetinfoSourceWire(net_info);
+        if (src_wire == WireId()) {
+            log_assert(net_info->driver.cell == nullptr);
+            if (ctx->debug)
+                log("  undriven and unrouted\n");
+            continue;
+        }
+
+        if (net_info->wires.count(src_wire) == 0) {
+            if (ctx->debug)
+                log("  source (%s) not bound to net\n", ctx->nameOfWire(src_wire));
+            found_unrouted = true;
+        }
+
+        dict<WireId, store_index<PortRef>> dest_wires;
+        for (auto user : net_info->users.enumerate()) {
+            for (auto dst_wire : ctx->getNetinfoSinkWires(net_info, user.value)) {
+                log_assert(dst_wire != WireId());
+                dest_wires[dst_wire] = user.index;
+
+                if (net_info->wires.count(dst_wire) == 0) {
+                    if (ctx->debug)
+                        log("  sink %d (%s) not bound to net\n", user.index.idx(), ctx->nameOfWire(dst_wire));
+                    found_unrouted = true;
+                }
+            }
+        }
+
+        std::function<void(WireId, int)> setOrderNum;
+        pool<WireId> logged_wires;
+
+        setOrderNum = [&](WireId w, int num) {
+            auto &db_entry = *db.emplace(w, std::make_unique<ExtraWireInfo>()).first->second;
+            if (db_entry.order_num != 0) {
+                found_loop = true;
+                log("  %*s=> loop\n", 2 * num, "");
+                return;
+            }
+            db_entry.order_num = num;
+            for (WireId child : db_entry.children) {
+                if (ctx->debug) {
+                    log("  %*s-> %s\n", 2 * num, "", ctx->nameOfWire(child));
+                    logged_wires.insert(child);
+                }
+                setOrderNum(child, num + 1);
+            }
+            if (db_entry.children.empty()) {
+                if (dest_wires.count(w) != 0) {
+                    if (ctx->debug)
+                        log("  %*s=> sink %d\n", 2 * num, "", dest_wires.at(w).idx());
+                } else {
+                    if (ctx->debug)
+                        log("  %*s=> stub\n", 2 * num, "");
+                    found_stub = true;
+                }
+            }
+        };
+
+        if (ctx->debug) {
+            log("  driver: %s\n", ctx->nameOfWire(src_wire));
+            logged_wires.insert(src_wire);
+        }
+        setOrderNum(src_wire, 1);
+
+        pool<WireId> dangling_wires;
+
+        for (auto &it : db) {
+            auto &db_entry = *it.second;
+            if (db_entry.order_num == 0)
+                dangling_wires.insert(it.first);
+        }
+
+        if (ctx->debug) {
+            if (dangling_wires.empty()) {
+                log("  no dangling wires.\n");
+            } else {
+                pool<WireId> root_wires = dangling_wires;
+
+                for (WireId w : dangling_wires) {
+                    for (WireId c : db[w]->children)
+                        root_wires.erase(c);
+                }
+
+                for (WireId w : root_wires) {
+                    log("  dangling wire: %s\n", ctx->nameOfWire(w));
+                    logged_wires.insert(w);
+                    setOrderNum(w, 1);
+                }
+
+                for (WireId w : dangling_wires) {
+                    if (logged_wires.count(w) == 0)
+                        log("  loop: %s -> %s\n", ctx->nameOfWire(ctx->getPipSrcWire(net_info->wires.at(w).pip)),
+                            ctx->nameOfWire(w));
+                }
+            }
+        }
+
+        bool fail = false;
+
+        if (found_unrouted) {
+            if (ctx->debug)
+                log("check failed: found unrouted arcs\n");
+            fail = true;
+        }
+
+        if (found_loop) {
+            if (ctx->debug)
+                log("check failed: found loops\n");
+            fail = true;
+        }
+
+        if (found_stub) {
+            if (ctx->debug)
+                log("check failed: found stubs\n");
+            fail = true;
+        }
+
+        if (!dangling_wires.empty()) {
+            if (ctx->debug)
+                log("check failed: found dangling wires\n");
+            fail = true;
+        }
+
+        if (fail)
+            return false;
+    }
+
+    return true;
+}
+
+bool Context::getActualRouteDelay(WireId src_wire, WireId dst_wire, delay_t *delay, dict<WireId, PipId> *route,
+                                  bool useEstimate)
+{
+    // FIXME
+    return false;
+}
+
+NEXTPNR_NAMESPACE_END
diff --git a/common/route/router1.h b/common/route/router1.h
new file mode 100644
index 00000000..a7ec5bad
--- /dev/null
+++ b/common/route/router1.h
@@ -0,0 +1,45 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2018  Claire Xenia Wolf <claire@yosyshq.com>
+ *
+ *  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.
+ *
+ */
+
+#ifndef ROUTER1_H
+#define ROUTER1_H
+
+#include "log.h"
+#include "nextpnr.h"
+NEXTPNR_NAMESPACE_BEGIN
+
+struct Router1Cfg
+{
+    Router1Cfg(Context *ctx);
+
+    int maxIterCnt;
+    bool cleanupReroute;
+    bool fullCleanupReroute;
+    bool useEstimate;
+    delay_t wireRipupPenalty;
+    delay_t netRipupPenalty;
+    delay_t reuseBonus;
+    delay_t estimatePrecision;
+};
+
+extern bool router1(Context *ctx, const Router1Cfg &cfg);
+
+NEXTPNR_NAMESPACE_END
+
+#endif // ROUTER1_H
diff --git a/common/route/router2.cc b/common/route/router2.cc
new file mode 100644
index 00000000..e943e493
--- /dev/null
+++ b/common/route/router2.cc
@@ -0,0 +1,1499 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2019  gatecat <gatecat@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.
+ *
+ *  Core routing algorithm based on CRoute:
+ *
+ *     CRoute: A Fast High-quality Timing-driven Connection-based FPGA Router
+ *     Dries Vercruyce, Elias Vansteenkiste and Dirk Stroobandt
+ *     DOI 10.1109/FCCM.2019.00017 [PDF on SciHub]
+ *
+ *  Modified for the nextpnr Arch API and data structures; optimised for
+ *  real-world FPGA architectures in particular ECP5 and Xilinx UltraScale+
+ *
+ */
+
+#include "router2.h"
+
+#include <algorithm>
+#include <boost/container/flat_map.hpp>
+#include <chrono>
+#include <deque>
+#include <fstream>
+#include <queue>
+
+#include "log.h"
+#include "nextpnr.h"
+#include "router1.h"
+#include "scope_lock.h"
+#include "timing.h"
+#include "util.h"
+
+NEXTPNR_NAMESPACE_BEGIN
+
+namespace {
+struct Router2
+{
+
+    struct PerArcData
+    {
+        WireId sink_wire;
+        ArcBounds bb;
+        bool routed = false;
+    };
+
+    // 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
+    {
+        WireId src_wire;
+        dict<WireId, std::pair<PipId, int>> wires;
+        std::vector<std::vector<PerArcData>> arcs;
+        ArcBounds bb;
+        // Coordinates of the center of the net, used for the weight-to-average
+        int cx, cy, hpwl;
+        int total_route_us = 0;
+        float max_crit = 0;
+        int fail_count = 0;
+    };
+
+    struct WireScore
+    {
+        float cost;
+        float togo_cost;
+        float total() const { return cost + togo_cost; }
+    };
+
+    struct PerWireData
+    {
+        // nextpnr
+        WireId w;
+        // Historical congestion cost
+        int curr_cong = 0;
+        float hist_cong_cost = 1.0;
+        // Wire is unavailable as locked to another arc
+        bool unavailable = false;
+        // This wire has to be used for this net
+        int reserved_net = -1;
+        // The notional location of the wire, to guarantee thread safety
+        int16_t x = 0, y = 0;
+        // Visit data
+        PipId pip_fwd, pip_bwd;
+        bool visited_fwd = false, visited_bwd = false;
+    };
+
+    Context *ctx;
+    Router2Cfg cfg;
+
+    Router2(Context *ctx, const Router2Cfg &cfg) : ctx(ctx), cfg(cfg), tmg(ctx) { tmg.setup(); }
+
+    // Use 'udata' for fast net lookups and indexing
+    std::vector<NetInfo *> nets_by_udata;
+    std::vector<PerNetData> nets;
+
+    bool timing_driven, timing_driven_ripup;
+    TimingAnalyser tmg;
+
+    void setup_nets()
+    {
+        // Populate per-net and per-arc structures at start of routing
+        nets.resize(ctx->nets.size());
+        nets_by_udata.resize(ctx->nets.size());
+        size_t i = 0;
+        for (auto &net : ctx->nets) {
+            NetInfo *ni = net.second.get();
+            ni->udata = i;
+            nets_by_udata.at(i) = ni;
+            nets.at(i).arcs.resize(ni->users.capacity());
+
+            // Start net bounding box at overall min/max
+            nets.at(i).bb.x0 = std::numeric_limits<int>::max();
+            nets.at(i).bb.x1 = std::numeric_limits<int>::min();
+            nets.at(i).bb.y0 = std::numeric_limits<int>::max();
+            nets.at(i).bb.y1 = std::numeric_limits<int>::min();
+            nets.at(i).cx = 0;
+            nets.at(i).cy = 0;
+
+            if (ni->driver.cell != nullptr) {
+                Loc drv_loc = ctx->getBelLocation(ni->driver.cell->bel);
+                nets.at(i).cx += drv_loc.x;
+                nets.at(i).cy += drv_loc.y;
+            }
+
+            for (auto usr : ni->users.enumerate()) {
+                WireId src_wire = ctx->getNetinfoSourceWire(ni);
+                for (auto &dst_wire : ctx->getNetinfoSinkWires(ni, usr.value)) {
+                    nets.at(i).src_wire = src_wire;
+                    if (ni->driver.cell == nullptr)
+                        src_wire = dst_wire;
+                    if (ni->driver.cell == nullptr && dst_wire == WireId())
+                        continue;
+                    if (src_wire == WireId())
+                        log_error("No wire found for port %s on source cell %s.\n", ctx->nameOf(ni->driver.port),
+                                  ctx->nameOf(ni->driver.cell));
+                    if (dst_wire == WireId())
+                        log_error("No wire found for port %s on destination cell %s.\n", ctx->nameOf(usr.value.port),
+                                  ctx->nameOf(usr.value.cell));
+                    nets.at(i).arcs.at(usr.index.idx()).emplace_back();
+                    auto &ad = nets.at(i).arcs.at(usr.index.idx()).back();
+                    ad.sink_wire = dst_wire;
+                    // Set bounding box for this arc
+                    ad.bb = ctx->getRouteBoundingBox(src_wire, dst_wire);
+                    // Expand net bounding box to include this arc
+                    nets.at(i).bb.x0 = std::min(nets.at(i).bb.x0, ad.bb.x0);
+                    nets.at(i).bb.x1 = std::max(nets.at(i).bb.x1, ad.bb.x1);
+                    nets.at(i).bb.y0 = std::min(nets.at(i).bb.y0, ad.bb.y0);
+                    nets.at(i).bb.y1 = std::max(nets.at(i).bb.y1, ad.bb.y1);
+                }
+                // Add location to centroid sum
+                Loc usr_loc = ctx->getBelLocation(usr.value.cell->bel);
+                nets.at(i).cx += usr_loc.x;
+                nets.at(i).cy += usr_loc.y;
+            }
+            nets.at(i).hpwl = std::max(
+                    std::abs(nets.at(i).bb.y1 - nets.at(i).bb.y0) + std::abs(nets.at(i).bb.x1 - nets.at(i).bb.x0), 1);
+            nets.at(i).cx /= int(ni->users.entries() + 1);
+            nets.at(i).cy /= int(ni->users.entries() + 1);
+            if (ctx->debug)
+                log_info("%s: bb=(%d, %d)->(%d, %d) c=(%d, %d) hpwl=%d\n", ctx->nameOf(ni), nets.at(i).bb.x0,
+                         nets.at(i).bb.y0, nets.at(i).bb.x1, nets.at(i).bb.y1, nets.at(i).cx, nets.at(i).cy,
+                         nets.at(i).hpwl);
+            nets.at(i).bb.x0 = std::max(nets.at(i).bb.x0 - cfg.bb_margin_x, 0);
+            nets.at(i).bb.y0 = std::max(nets.at(i).bb.y0 - cfg.bb_margin_y, 0);
+            nets.at(i).bb.x1 = std::min(nets.at(i).bb.x1 + cfg.bb_margin_x, ctx->getGridDimX());
+            nets.at(i).bb.y1 = std::min(nets.at(i).bb.y1 + cfg.bb_margin_y, ctx->getGridDimY());
+            i++;
+        }
+    }
+
+    dict<WireId, int> wire_to_idx;
+    std::vector<PerWireData> flat_wires;
+
+    PerWireData &wire_data(WireId w) { return flat_wires[wire_to_idx.at(w)]; }
+
+    void setup_wires()
+    {
+        // Set up per-wire structures, so that MT parts don't have to do any memory allocation
+        // This is possibly quite wasteful and not cache-optimal; further consideration necessary
+        for (auto wire : ctx->getWires()) {
+            PerWireData pwd;
+            pwd.w = wire;
+            NetInfo *bound = ctx->getBoundWireNet(wire);
+            if (bound != nullptr) {
+                auto iter = bound->wires.find(wire);
+                if (iter != bound->wires.end()) {
+                    auto &nd = nets.at(bound->udata);
+                    nd.wires[wire] = std::make_pair(bound->wires.at(wire).pip, 0);
+                    pwd.curr_cong = 1;
+                    if (bound->wires.at(wire).strength == STRENGTH_PLACER) {
+                        pwd.reserved_net = bound->udata;
+                    } else if (bound->wires.at(wire).strength > STRENGTH_PLACER) {
+                        pwd.unavailable = true;
+                    }
+                }
+            }
+
+            ArcBounds wire_loc = ctx->getRouteBoundingBox(wire, wire);
+            pwd.x = (wire_loc.x0 + wire_loc.x1) / 2;
+            pwd.y = (wire_loc.y0 + wire_loc.y1) / 2;
+
+            wire_to_idx[wire] = int(flat_wires.size());
+            flat_wires.push_back(pwd);
+        }
+
+        for (auto &net_pair : ctx->nets) {
+            auto *net = net_pair.second.get();
+            auto &nd = nets.at(net->udata);
+            for (auto usr : net->users.enumerate()) {
+                auto &ad = nd.arcs.at(usr.index.idx());
+                for (size_t phys_pin = 0; phys_pin < ad.size(); phys_pin++) {
+                    if (check_arc_routing(net, usr.index, phys_pin)) {
+                        record_prerouted_net(net, usr.index, phys_pin);
+                    }
+                }
+            }
+        }
+    }
+
+    struct QueuedWire
+    {
+
+        explicit QueuedWire(int wire = -1, WireScore score = WireScore{}, int randtag = 0)
+                : wire(wire), score(score), randtag(randtag){};
+
+        int wire;
+        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;
+            }
+        };
+    };
+
+    bool hit_test_pip(ArcBounds &bb, Loc l) { return l.x >= bb.x0 && l.x <= bb.x1 && l.y >= bb.y0 && l.y <= bb.y1; }
+
+    double curr_cong_weight, hist_cong_weight, estimate_weight;
+
+    struct ThreadContext
+    {
+        // Nets to route
+        std::vector<NetInfo *> route_nets;
+        // Nets that failed routing
+        std::vector<NetInfo *> failed_nets;
+
+        std::vector<std::pair<store_index<PortRef>, size_t>> route_arcs;
+
+        std::priority_queue<QueuedWire, std::vector<QueuedWire>, QueuedWire::Greater> fwd_queue, bwd_queue;
+        // Special case where one net has multiple logical arcs to the same physical sink
+        pool<WireId> processed_sinks;
+
+        std::vector<int> dirty_wires;
+
+        // Thread bounding box
+        ArcBounds bb;
+
+        DeterministicRNG rng;
+
+        // Used to add existing routing to the heap
+        pool<WireId> in_wire_by_loc;
+        dict<std::pair<int, int>, pool<WireId>> wire_by_loc;
+    };
+
+    bool thread_test_wire(ThreadContext &t, PerWireData &w)
+    {
+        return w.x >= t.bb.x0 && w.x <= t.bb.x1 && w.y >= t.bb.y0 && w.y <= t.bb.y1;
+    }
+
+    enum ArcRouteResult
+    {
+        ARC_SUCCESS,
+        ARC_RETRY_WITHOUT_BB,
+        ARC_FATAL,
+    };
+
+// Define to make sure we don't print in a multithreaded context
+#define ARC_LOG_ERR(...)                                                                                               \
+    do {                                                                                                               \
+        if (is_mt)                                                                                                     \
+            return ARC_FATAL;                                                                                          \
+        else                                                                                                           \
+            log_error(__VA_ARGS__);                                                                                    \
+    } while (0)
+#define ROUTE_LOG_DBG(...)                                                                                             \
+    do {                                                                                                               \
+        if (!is_mt && ctx->debug)                                                                                      \
+            log(__VA_ARGS__);                                                                                          \
+    } while (0)
+
+    void bind_pip_internal(PerNetData &net, store_index<PortRef> user, int wire, PipId pip)
+    {
+        auto &wd = flat_wires.at(wire);
+        auto found = net.wires.find(wd.w);
+        if (found == net.wires.end()) {
+            // Not yet used for any arcs of this net, add to list
+            net.wires.emplace(wd.w, std::make_pair(pip, 1));
+            // Increase bound count of wire by 1
+            ++wd.curr_cong;
+        } else {
+            // Already used for at least one other arc of this net
+            // Don't allow two uphill PIPs for the same net and wire
+            NPNR_ASSERT(found->second.first == pip);
+            // Increase the count of bound arcs
+            ++found->second.second;
+        }
+    }
+
+    void unbind_pip_internal(PerNetData &net, store_index<PortRef> user, WireId wire)
+    {
+        auto &wd = wire_data(wire);
+        auto &b = net.wires.at(wd.w);
+        --b.second;
+        if (b.second == 0) {
+            // No remaining arcs of this net bound to this wire
+            --wd.curr_cong;
+            net.wires.erase(wd.w);
+        }
+    }
+
+    void ripup_arc(NetInfo *net, store_index<PortRef> user, size_t phys_pin)
+    {
+        auto &nd = nets.at(net->udata);
+        auto &ad = nd.arcs.at(user.idx()).at(phys_pin);
+        if (!ad.routed)
+            return;
+        WireId src = nets.at(net->udata).src_wire;
+        WireId cursor = ad.sink_wire;
+        while (cursor != src) {
+            PipId pip = nd.wires.at(cursor).first;
+            unbind_pip_internal(nd, user, cursor);
+            cursor = ctx->getPipSrcWire(pip);
+        }
+        ad.routed = false;
+    }
+
+    float score_wire_for_arc(NetInfo *net, store_index<PortRef> user, size_t phys_pin, WireId wire, PipId pip,
+                             float crit_weight)
+    {
+        auto &wd = wire_data(wire);
+        auto &nd = nets.at(net->udata);
+        float base_cost = cfg.get_base_cost(ctx, wire, pip, crit_weight);
+        int overuse = wd.curr_cong;
+        float hist_cost = 1.0f + crit_weight * (wd.hist_cong_cost - 1.0f);
+        float bias_cost = 0;
+        int source_uses = 0;
+        if (nd.wires.count(wire)) {
+            overuse -= 1;
+            source_uses = nd.wires.at(wire).second;
+        }
+        float present_cost = 1.0f + overuse * curr_cong_weight * crit_weight;
+        if (pip != PipId()) {
+            Loc pl = ctx->getPipLocation(pip);
+            bias_cost = cfg.bias_cost_factor * (base_cost / int(net->users.entries())) *
+                        ((std::abs(pl.x - nd.cx) + std::abs(pl.y - nd.cy)) / float(nd.hpwl));
+        }
+        return base_cost * hist_cost * present_cost / (1 + (source_uses * crit_weight)) + bias_cost;
+    }
+
+    float get_togo_cost(NetInfo *net, store_index<PortRef> user, int wire, WireId src_sink, float crit_weight,
+                        bool bwd = false)
+    {
+        auto &nd = nets.at(net->udata);
+        auto &wd = flat_wires[wire];
+        int source_uses = 0;
+        if (nd.wires.count(wd.w)) {
+            source_uses = nd.wires.at(wd.w).second;
+        }
+        // FIXME: timing/wirelength balance?
+        delay_t est_delay = ctx->estimateDelay(bwd ? src_sink : wd.w, bwd ? wd.w : src_sink);
+        return (ctx->getDelayNS(est_delay) / (1 + source_uses * crit_weight)) + cfg.ipin_cost_adder;
+    }
+
+    bool check_arc_routing(NetInfo *net, store_index<PortRef> usr, size_t phys_pin)
+    {
+        auto &nd = nets.at(net->udata);
+        auto &ad = nd.arcs.at(usr.idx()).at(phys_pin);
+        WireId src_wire = nets.at(net->udata).src_wire;
+        WireId cursor = ad.sink_wire;
+        while (nd.wires.count(cursor)) {
+            auto &wd = wire_data(cursor);
+            if (wd.curr_cong != 1)
+                return false;
+            auto &uh = nd.wires.at(cursor).first;
+            if (uh == PipId())
+                break;
+            cursor = ctx->getPipSrcWire(uh);
+        }
+        return (cursor == src_wire);
+    }
+
+    void record_prerouted_net(NetInfo *net, store_index<PortRef> usr, size_t phys_pin)
+    {
+        auto &nd = nets.at(net->udata);
+        auto &ad = nd.arcs.at(usr.idx()).at(phys_pin);
+        ad.routed = true;
+
+        WireId src = nets.at(net->udata).src_wire;
+        WireId cursor = ad.sink_wire;
+        while (cursor != src) {
+            size_t wire_idx = wire_to_idx.at(cursor);
+            PipId pip = nd.wires.at(cursor).first;
+            bind_pip_internal(nd, usr, wire_idx, pip);
+            cursor = ctx->getPipSrcWire(pip);
+        }
+    }
+
+    // Returns true if a wire contains no source ports or driving pips
+    bool is_wire_undriveable(WireId wire, const NetInfo *net, int iter_count = 0)
+    {
+        // This is specifically designed to handle a particularly icky case that the current router struggles with in
+        // the nexus device,
+        // C -> C lut input only
+        // C; D; or F from another lut -> D lut input
+        // D or M -> M ff input
+        // without careful reservation of C for C lut input and D for D lut input, there is fighting for D between FF
+        // and LUT
+        if (iter_count > 7)
+            return false; // heuristic to assume we've hit general routing
+        if (wire_data(wire).unavailable)
+            return true;
+        if (wire_data(wire).reserved_net != -1 && wire_data(wire).reserved_net != net->udata)
+            return true; // reserved for another net
+        for (auto bp : ctx->getWireBelPins(wire))
+            if ((net->driver.cell == nullptr || bp.bel == net->driver.cell->bel) &&
+                ctx->getBelPinType(bp.bel, bp.pin) != PORT_IN)
+                return false;
+        for (auto p : ctx->getPipsUphill(wire))
+            if (ctx->checkPipAvail(p)) {
+                if (!is_wire_undriveable(ctx->getPipSrcWire(p), net, iter_count + 1))
+                    return false;
+            }
+        return true;
+    }
+
+    // Find all the wires that must be used to route a given arc
+    bool reserve_wires_for_arc(NetInfo *net, store_index<PortRef> i)
+    {
+        bool did_something = false;
+        WireId src = ctx->getNetinfoSourceWire(net);
+        auto &usr = net->users.at(i);
+        for (auto sink : ctx->getNetinfoSinkWires(net, usr)) {
+            pool<WireId> rsv;
+            WireId cursor = sink;
+            bool done = false;
+            if (ctx->debug)
+                log("reserving wires for arc %d (%s.%s) of net %s\n", i.idx(), ctx->nameOf(usr.cell),
+                    ctx->nameOf(usr.port), ctx->nameOf(net));
+            while (!done) {
+                auto &wd = wire_data(cursor);
+                if (ctx->debug)
+                    log("      %s\n", ctx->nameOfWire(cursor));
+                did_something |= (wd.reserved_net != net->udata);
+                if (wd.reserved_net != -1 && wd.reserved_net != net->udata)
+                    log_error("attempting to reserve wire '%s' for nets '%s' and '%s'\n", ctx->nameOfWire(cursor),
+                              ctx->nameOf(nets_by_udata.at(wd.reserved_net)), ctx->nameOf(net));
+                wd.reserved_net = net->udata;
+                if (cursor == src)
+                    break;
+                WireId next_cursor;
+                for (auto uh : ctx->getPipsUphill(cursor)) {
+                    WireId w = ctx->getPipSrcWire(uh);
+                    if (is_wire_undriveable(w, net))
+                        continue;
+                    if (next_cursor != WireId()) {
+                        done = true;
+                        break;
+                    }
+                    next_cursor = w;
+                }
+                if (next_cursor == WireId())
+                    break;
+                cursor = next_cursor;
+            }
+        }
+        return did_something;
+    }
+
+    void find_all_reserved_wires()
+    {
+        // Run iteratively, as reserving wires for one net might limit choices for another
+        bool did_something = false;
+        do {
+            did_something = false;
+            for (auto net : nets_by_udata) {
+                WireId src = ctx->getNetinfoSourceWire(net);
+                if (src == WireId())
+                    continue;
+                for (auto usr : net->users.enumerate())
+                    did_something |= reserve_wires_for_arc(net, usr.index);
+            }
+        } while (did_something);
+    }
+
+    void reset_wires(ThreadContext &t)
+    {
+        for (auto w : t.dirty_wires) {
+            flat_wires[w].pip_fwd = PipId();
+            flat_wires[w].pip_bwd = PipId();
+            flat_wires[w].visited_fwd = false;
+            flat_wires[w].visited_bwd = false;
+        }
+        t.dirty_wires.clear();
+    }
+
+    // These nets have very-high-fanout pips and special rules must be followed (only working backwards) to avoid
+    // crippling perf
+    bool is_pseudo_const_net(const NetInfo *net)
+    {
+#ifdef ARCH_NEXUS
+        if (net->driver.cell != nullptr && net->driver.cell->type == id_VCC_DRV)
+            return true;
+#endif
+        return false;
+    }
+
+    void update_wire_by_loc(ThreadContext &t, NetInfo *net, store_index<PortRef> i, size_t phys_pin, bool is_mt)
+    {
+        if (is_pseudo_const_net(net))
+            return;
+        auto &nd = nets.at(net->udata);
+        auto &ad = nd.arcs.at(i.idx()).at(phys_pin);
+        WireId cursor = ad.sink_wire;
+        if (!nd.wires.count(cursor))
+            return;
+        while (cursor != nd.src_wire) {
+            if (!t.in_wire_by_loc.count(cursor)) {
+                t.in_wire_by_loc.insert(cursor);
+                for (auto dh : ctx->getPipsDownhill(cursor)) {
+                    Loc dh_loc = ctx->getPipLocation(dh);
+                    t.wire_by_loc[std::make_pair(dh_loc.x, dh_loc.y)].insert(cursor);
+                }
+            }
+            cursor = ctx->getPipSrcWire(nd.wires.at(cursor).first);
+        }
+    }
+
+    // Functions for marking wires as visited, and checking if they have already been visited
+    void set_visited_fwd(ThreadContext &t, int wire, PipId pip)
+    {
+        auto &wd = flat_wires.at(wire);
+        if (!wd.visited_fwd && !wd.visited_bwd)
+            t.dirty_wires.push_back(wire);
+        wd.pip_fwd = pip;
+        wd.visited_fwd = true;
+    }
+    void set_visited_bwd(ThreadContext &t, int wire, PipId pip)
+    {
+        auto &wd = flat_wires.at(wire);
+        if (!wd.visited_fwd && !wd.visited_bwd)
+            t.dirty_wires.push_back(wire);
+        wd.pip_bwd = pip;
+        wd.visited_bwd = true;
+    }
+
+    bool was_visited_fwd(int wire) { return flat_wires.at(wire).visited_fwd; }
+    bool was_visited_bwd(int wire) { return flat_wires.at(wire).visited_bwd; }
+
+    float get_arc_crit(NetInfo *net, store_index<PortRef> i)
+    {
+        if (!timing_driven)
+            return 0;
+        return tmg.get_criticality(CellPortKey(net->users.at(i)));
+    }
+
+    bool arc_failed_slack(NetInfo *net, store_index<PortRef> usr_idx)
+    {
+        return timing_driven_ripup &&
+               (tmg.get_setup_slack(CellPortKey(net->users.at(usr_idx))) < (2 * ctx->getDelayEpsilon()));
+    }
+
+    ArcRouteResult route_arc(ThreadContext &t, NetInfo *net, store_index<PortRef> i, size_t phys_pin, bool is_mt,
+                             bool is_bb = true)
+    {
+        // Do some initial lookups and checks
+        auto arc_start = std::chrono::high_resolution_clock::now();
+        auto &nd = nets[net->udata];
+        auto &ad = nd.arcs.at(i.idx()).at(phys_pin);
+        auto &usr = net->users.at(i);
+        ROUTE_LOG_DBG("Routing arc %d of net '%s' (%d, %d) -> (%d, %d)\n", i.idx(), ctx->nameOf(net), ad.bb.x0,
+                      ad.bb.y0, ad.bb.x1, ad.bb.y1);
+        WireId src_wire = ctx->getNetinfoSourceWire(net), dst_wire = ctx->getNetinfoSinkWire(net, usr, phys_pin);
+        if (src_wire == WireId())
+            ARC_LOG_ERR("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())
+            ARC_LOG_ERR("No wire found for port %s on destination cell %s.\n", ctx->nameOf(usr.port),
+                        ctx->nameOf(usr.cell));
+        int src_wire_idx = wire_to_idx.at(src_wire);
+        int dst_wire_idx = wire_to_idx.at(dst_wire);
+        // Calculate a timing weight based on criticality
+        float crit = get_arc_crit(net, i);
+        float crit_weight = (1.0f - std::pow(crit, 2));
+        ROUTE_LOG_DBG("     crit=%.3f crit_weight=%.3f\n", crit, crit_weight);
+        // Check if arc was already done _in this iteration_
+        if (t.processed_sinks.count(dst_wire))
+            return ARC_SUCCESS;
+
+        // We have two modes:
+        //     0. starting within a small range of existing routing
+        //     1. expanding from all routing
+        int mode = 0;
+        if (net->users.entries() < 4 || nd.wires.empty() || (crit > 0.95))
+            mode = 1;
+
+        // This records the point where forwards and backwards routing met
+        int midpoint_wire = -1;
+        int explored = 1;
+
+        for (; mode < 2; mode++) {
+            // Clear out the queues
+            if (!t.fwd_queue.empty()) {
+                std::priority_queue<QueuedWire, std::vector<QueuedWire>, QueuedWire::Greater> new_queue;
+                t.fwd_queue.swap(new_queue);
+            }
+            if (!t.bwd_queue.empty()) {
+                std::priority_queue<QueuedWire, std::vector<QueuedWire>, QueuedWire::Greater> new_queue;
+                t.bwd_queue.swap(new_queue);
+            }
+            // Unvisit any previously visited wires
+            reset_wires(t);
+
+            ROUTE_LOG_DBG("src_wire = %s -> dst_wire = %s\n", ctx->nameOfWire(src_wire), ctx->nameOfWire(dst_wire));
+
+            // Add 'forward' direction startpoints to queue
+            auto seed_queue_fwd = [&](WireId wire, float wire_cost = 0) {
+                WireScore base_score;
+                base_score.cost = wire_cost;
+                int wire_idx = wire_to_idx.at(wire);
+                base_score.togo_cost = get_togo_cost(net, i, wire_idx, dst_wire, false, crit_weight);
+                t.fwd_queue.push(QueuedWire(wire_idx, base_score));
+                set_visited_fwd(t, wire_idx, PipId());
+            };
+            auto &dst_data = flat_wires.at(dst_wire_idx);
+            // Look for nearby existing routing
+            for (int dy = -cfg.bb_margin_y; dy <= cfg.bb_margin_y; dy++)
+                for (int dx = -cfg.bb_margin_x; dx <= cfg.bb_margin_x; dx++) {
+                    auto fnd = t.wire_by_loc.find(std::make_pair(dst_data.x + dx, dst_data.y + dy));
+                    if (fnd == t.wire_by_loc.end())
+                        continue;
+                    for (WireId wire : fnd->second) {
+                        ROUTE_LOG_DBG("   seeding with %s\n", ctx->nameOfWire(wire));
+                        seed_queue_fwd(wire);
+                    }
+                }
+
+            if (mode == 0 && t.fwd_queue.size() < 4)
+                continue;
+
+            if (mode == 1 && !is_pseudo_const_net(net)) {
+                // Seed forwards with the source wire, if less than 8 existing wires added
+                seed_queue_fwd(src_wire);
+            } else {
+                set_visited_fwd(t, src_wire_idx, PipId());
+            }
+            auto seed_queue_bwd = [&](WireId wire) {
+                WireScore base_score;
+                base_score.cost = 0;
+                int wire_idx = wire_to_idx.at(wire);
+                base_score.togo_cost = get_togo_cost(net, i, wire_idx, src_wire, true, crit_weight);
+                t.bwd_queue.push(QueuedWire(wire_idx, base_score));
+                set_visited_bwd(t, wire_idx, PipId());
+            };
+
+            // Seed backwards with the dest wire
+            seed_queue_bwd(dst_wire);
+
+            int toexplore = 25000 * std::max(1, (ad.bb.x1 - ad.bb.x0) + (ad.bb.y1 - ad.bb.y0));
+            int iter = 0;
+
+            // Mode 0 required both queues to be live
+            while (((mode == 0) ? (!t.fwd_queue.empty() && !t.bwd_queue.empty())
+                                : (!t.fwd_queue.empty() || !t.bwd_queue.empty())) &&
+                   (!is_bb || iter < toexplore)) {
+                ++iter;
+                if (!t.fwd_queue.empty()) {
+                    // Explore forwards
+                    auto curr = t.fwd_queue.top();
+                    t.fwd_queue.pop();
+                    ++explored;
+                    if (was_visited_bwd(curr.wire)) {
+                        // Meet in the middle; done
+                        midpoint_wire = curr.wire;
+                        break;
+                    }
+                    auto &curr_data = flat_wires.at(curr.wire);
+                    for (PipId dh : ctx->getPipsDownhill(curr_data.w)) {
+                        // Skip pips outside of box in bounding-box mode
+                        if (is_bb && !hit_test_pip(nd.bb, ctx->getPipLocation(dh)))
+                            continue;
+                        if (!ctx->checkPipAvailForNet(dh, net))
+                            continue;
+                        WireId next = ctx->getPipDstWire(dh);
+                        int next_idx = wire_to_idx.at(next);
+                        if (was_visited_fwd(next_idx)) {
+                            // Don't expand the same node twice.
+                            continue;
+                        }
+                        auto &nwd = flat_wires.at(next_idx);
+                        if (nwd.unavailable)
+                            continue;
+                        // Reserved for another net
+                        if (nwd.reserved_net != -1 && nwd.reserved_net != net->udata)
+                            continue;
+                        // Don't allow the same wire to be bound to the same net with a different driving pip
+                        auto fnd_wire = nd.wires.find(next);
+                        if (fnd_wire != nd.wires.end() && fnd_wire->second.first != dh)
+                            continue;
+                        if (!thread_test_wire(t, nwd))
+                            continue; // thread safety issue
+                        WireScore next_score;
+                        next_score.cost = curr.score.cost + score_wire_for_arc(net, i, phys_pin, next, dh, crit_weight);
+                        next_score.togo_cost =
+                                cfg.estimate_weight * get_togo_cost(net, i, next_idx, dst_wire, false, crit_weight);
+                        set_visited_fwd(t, next_idx, dh);
+                        t.fwd_queue.push(QueuedWire(next_idx, next_score, t.rng.rng()));
+                    }
+                }
+                if (!t.bwd_queue.empty()) {
+                    // Explore backwards
+                    auto curr = t.bwd_queue.top();
+                    t.bwd_queue.pop();
+                    ++explored;
+                    if (was_visited_fwd(curr.wire)) {
+                        // Meet in the middle; done
+                        midpoint_wire = curr.wire;
+                        break;
+                    }
+                    auto &curr_data = flat_wires.at(curr.wire);
+                    // Don't allow the same wire to be bound to the same net with a different driving pip
+                    PipId bound_pip;
+                    auto fnd_wire = nd.wires.find(curr_data.w);
+                    if (fnd_wire != nd.wires.end())
+                        bound_pip = fnd_wire->second.first;
+
+                    for (PipId uh : ctx->getPipsUphill(curr_data.w)) {
+                        if (bound_pip != PipId() && bound_pip != uh)
+                            continue;
+                        if (is_bb && !hit_test_pip(nd.bb, ctx->getPipLocation(uh)))
+                            continue;
+                        if (!ctx->checkPipAvailForNet(uh, net))
+                            continue;
+                        WireId next = ctx->getPipSrcWire(uh);
+                        int next_idx = wire_to_idx.at(next);
+                        if (was_visited_bwd(next_idx)) {
+                            // Don't expand the same node twice.
+                            continue;
+                        }
+                        auto &nwd = flat_wires.at(next_idx);
+                        if (nwd.unavailable)
+                            continue;
+                        // Reserved for another net
+                        if (nwd.reserved_net != -1 && nwd.reserved_net != net->udata)
+                            continue;
+                        if (!thread_test_wire(t, nwd))
+                            continue; // thread safety issue
+                        WireScore next_score;
+                        next_score.cost = curr.score.cost + score_wire_for_arc(net, i, phys_pin, next, uh, crit_weight);
+                        next_score.togo_cost =
+                                cfg.estimate_weight * get_togo_cost(net, i, next_idx, src_wire, true, crit_weight);
+                        set_visited_bwd(t, next_idx, uh);
+                        t.bwd_queue.push(QueuedWire(next_idx, next_score, t.rng.rng()));
+                    }
+                }
+            }
+            if (midpoint_wire != -1)
+                break;
+        }
+        ArcRouteResult result = ARC_SUCCESS;
+        if (midpoint_wire != -1) {
+            ROUTE_LOG_DBG("   Routed (explored %d wires): ", explored);
+            int cursor_bwd = midpoint_wire;
+            while (was_visited_fwd(cursor_bwd)) {
+                PipId pip = flat_wires.at(cursor_bwd).pip_fwd;
+                if (pip == PipId() && cursor_bwd != src_wire_idx)
+                    break;
+                bind_pip_internal(nd, i, cursor_bwd, pip);
+                if (ctx->debug && !is_mt) {
+                    auto &wd = flat_wires.at(cursor_bwd);
+                    ROUTE_LOG_DBG("      fwd wire: %s (curr %d hist %f share %d)\n", ctx->nameOfWire(wd.w),
+                                  wd.curr_cong - 1, wd.hist_cong_cost, nd.wires.at(wd.w).second);
+                }
+                if (pip == PipId()) {
+                    break;
+                }
+                ROUTE_LOG_DBG("         fwd pip: %s (%d, %d)\n", ctx->nameOfPip(pip), ctx->getPipLocation(pip).x,
+                              ctx->getPipLocation(pip).y);
+                cursor_bwd = wire_to_idx.at(ctx->getPipSrcWire(pip));
+            }
+
+            while (cursor_bwd != src_wire_idx) {
+                // Tack onto existing routing
+                WireId bwd_w = flat_wires.at(cursor_bwd).w;
+                if (!nd.wires.count(bwd_w))
+                    break;
+                auto &bound = nd.wires.at(bwd_w);
+                PipId pip = bound.first;
+                if (ctx->debug && !is_mt) {
+                    auto &wd = flat_wires.at(cursor_bwd);
+                    ROUTE_LOG_DBG("      ext wire: %s (curr %d hist %f share %d)\n", ctx->nameOfWire(wd.w),
+                                  wd.curr_cong - 1, wd.hist_cong_cost, bound.second);
+                }
+                bind_pip_internal(nd, i, cursor_bwd, pip);
+                if (pip == PipId())
+                    break;
+                cursor_bwd = wire_to_idx.at(ctx->getPipSrcWire(pip));
+            }
+
+            NPNR_ASSERT(cursor_bwd == src_wire_idx);
+
+            int cursor_fwd = midpoint_wire;
+            while (was_visited_bwd(cursor_fwd)) {
+                PipId pip = flat_wires.at(cursor_fwd).pip_bwd;
+                if (pip == PipId()) {
+                    break;
+                }
+                ROUTE_LOG_DBG("         bwd pip: %s (%d, %d)\n", ctx->nameOfPip(pip), ctx->getPipLocation(pip).x,
+                              ctx->getPipLocation(pip).y);
+                cursor_fwd = wire_to_idx.at(ctx->getPipDstWire(pip));
+                bind_pip_internal(nd, i, cursor_fwd, pip);
+                if (ctx->debug && !is_mt) {
+                    auto &wd = flat_wires.at(cursor_fwd);
+                    ROUTE_LOG_DBG("      bwd wire: %s (curr %d hist %f share %d)\n", ctx->nameOfWire(wd.w),
+                                  wd.curr_cong - 1, wd.hist_cong_cost, nd.wires.at(wd.w).second);
+                }
+            }
+            NPNR_ASSERT(cursor_fwd == dst_wire_idx);
+
+            update_wire_by_loc(t, net, i, phys_pin, is_mt);
+            t.processed_sinks.insert(dst_wire);
+            ad.routed = true;
+            auto arc_end = std::chrono::high_resolution_clock::now();
+            ROUTE_LOG_DBG("Routing arc %d of net '%s' (is_bb = %d) took %02fs\n", i.idx(), ctx->nameOf(net), is_bb,
+                          std::chrono::duration<float>(arc_end - arc_start).count());
+        } else {
+            auto arc_end = std::chrono::high_resolution_clock::now();
+            ROUTE_LOG_DBG("Failed routing arc %d of net '%s' (is_bb = %d) took %02fs\n", i.idx(), ctx->nameOf(net),
+                          is_bb, std::chrono::duration<float>(arc_end - arc_start).count());
+            result = ARC_RETRY_WITHOUT_BB;
+        }
+        reset_wires(t);
+        return result;
+    }
+#undef ARC_ERR
+
+    bool route_net(ThreadContext &t, NetInfo *net, bool is_mt)
+    {
+
+#ifdef ARCH_ECP5
+        if (net->is_global)
+            return true;
+#endif
+
+        ROUTE_LOG_DBG("Routing net '%s'...\n", ctx->nameOf(net));
+
+        auto rstart = std::chrono::high_resolution_clock::now();
+
+        // Nothing to do if net is undriven
+        if (net->driver.cell == nullptr)
+            return true;
+
+        bool have_failures = false;
+        t.processed_sinks.clear();
+        t.route_arcs.clear();
+        t.wire_by_loc.clear();
+        t.in_wire_by_loc.clear();
+        auto &nd = nets.at(net->udata);
+        bool failed_slack = false;
+        for (auto usr : net->users.enumerate())
+            failed_slack |= arc_failed_slack(net, usr.index);
+        for (auto usr : net->users.enumerate()) {
+            auto &ad = nd.arcs.at(usr.index.idx());
+            for (size_t j = 0; j < ad.size(); j++) {
+                // Ripup failed arcs to start with
+                // Check if arc is already legally routed
+                if (!failed_slack && check_arc_routing(net, usr.index, j)) {
+                    update_wire_by_loc(t, net, usr.index, j, true);
+                    continue;
+                }
+
+                // Ripup arc to start with
+                ripup_arc(net, usr.index, j);
+                t.route_arcs.emplace_back(usr.index, j);
+            }
+        }
+        // Route most critical arc first
+        std::stable_sort(t.route_arcs.begin(), t.route_arcs.end(),
+                         [&](std::pair<store_index<PortRef>, size_t> a, std::pair<store_index<PortRef>, size_t> b) {
+                             return get_arc_crit(net, a.first) > get_arc_crit(net, b.first);
+                         });
+        for (auto a : t.route_arcs) {
+            auto res1 = route_arc(t, net, a.first, a.second, is_mt, true);
+            if (res1 == ARC_FATAL)
+                return false; // Arc failed irrecoverably
+            else if (res1 == ARC_RETRY_WITHOUT_BB) {
+                if (is_mt) {
+                    // Can't break out of bounding box in multi-threaded mode, so mark this arc as a failure
+                    have_failures = true;
+                } else {
+                    // Attempt a re-route without the bounding box constraint
+                    ROUTE_LOG_DBG("Rerouting arc %d.%d of net '%s' without bounding box, possible tricky routing...\n",
+                                  a.first.idx(), int(a.second), ctx->nameOf(net));
+                    auto res2 = route_arc(t, net, a.first, a.second, is_mt, false);
+                    // If this also fails, no choice but to give up
+                    if (res2 != ARC_SUCCESS) {
+                        if (ctx->debug) {
+                            log_info("Pre-bound routing: \n");
+                            for (auto &wire_pair : net->wires) {
+                                log("        %s", ctx->nameOfWire(wire_pair.first));
+                                if (wire_pair.second.pip != PipId())
+                                    log(" %s", ctx->nameOfPip(wire_pair.second.pip));
+                                log("\n");
+                            }
+                        }
+                        log_error("Failed to route arc %d.%d of net '%s', from %s to %s.\n", a.first.idx(),
+                                  int(a.second), ctx->nameOf(net), ctx->nameOfWire(ctx->getNetinfoSourceWire(net)),
+                                  ctx->nameOfWire(ctx->getNetinfoSinkWire(net, net->users.at(a.first), a.second)));
+                    }
+                }
+            }
+        }
+        if (cfg.perf_profile) {
+            auto rend = std::chrono::high_resolution_clock::now();
+            nets.at(net->udata).total_route_us +=
+                    (std::chrono::duration_cast<std::chrono::microseconds>(rend - rstart).count());
+        }
+        return !have_failures;
+    }
+#undef ROUTE_LOG_DBG
+
+    int total_wire_use = 0;
+    int overused_wires = 0;
+    int total_overuse = 0;
+    std::vector<int> route_queue;
+    std::set<int> failed_nets;
+
+    void update_congestion()
+    {
+        total_overuse = 0;
+        overused_wires = 0;
+        total_wire_use = 0;
+        failed_nets.clear();
+        pool<WireId> already_updated;
+        for (size_t i = 0; i < nets.size(); i++) {
+            auto &nd = nets.at(i);
+            for (const auto &w : nd.wires) {
+                ++total_wire_use;
+                auto &wd = wire_data(w.first);
+                if (wd.curr_cong > 1) {
+                    if (already_updated.count(w.first)) {
+                        ++total_overuse;
+                    } else {
+                        if (curr_cong_weight > 0)
+                            wd.hist_cong_cost =
+                                    std::min(1e9, wd.hist_cong_cost + (wd.curr_cong - 1) * hist_cong_weight);
+                        already_updated.insert(w.first);
+                        ++overused_wires;
+                    }
+                    failed_nets.insert(i);
+                }
+            }
+        }
+        for (int n : failed_nets) {
+            auto &net_data = nets.at(n);
+            ++net_data.fail_count;
+            if ((net_data.fail_count % 3) == 0) {
+                // Every three times a net fails to route, expand the bounding box to increase the search space
+#ifndef ARCH_MISTRAL
+                // This patch seems to make thing worse for CycloneV, as it slows down the resolution of TD congestion,
+                // disable it
+                net_data.bb.x0 = std::max(net_data.bb.x0 - 1, 0);
+                net_data.bb.y0 = std::max(net_data.bb.y0 - 1, 0);
+                net_data.bb.x1 = std::min(net_data.bb.x1 + 1, ctx->getGridDimX());
+                net_data.bb.y1 = std::min(net_data.bb.y1 + 1, ctx->getGridDimY());
+#endif
+            }
+        }
+    }
+
+    bool bind_and_check(NetInfo *net, store_index<PortRef> usr_idx, int phys_pin)
+    {
+#ifdef ARCH_ECP5
+        if (net->is_global)
+            return true;
+#endif
+        bool success = true;
+        auto &nd = nets.at(net->udata);
+        auto &ad = nd.arcs.at(usr_idx.idx()).at(phys_pin);
+        auto &usr = net->users.at(usr_idx);
+        WireId src = ctx->getNetinfoSourceWire(net);
+        // Skip routes with no source
+        if (src == WireId())
+            return true;
+        WireId dst = ctx->getNetinfoSinkWire(net, usr, phys_pin);
+        if (dst == WireId())
+            return true;
+
+        // Skip routes where there is no routing (special cases)
+        if (!ad.routed) {
+            if ((src == dst) && ctx->getBoundWireNet(dst) != net)
+                ctx->bindWire(src, net, STRENGTH_WEAK);
+            if (ctx->debug) {
+                log("Net %s not routed, not binding\n", ctx->nameOf(net));
+            }
+            return true;
+        }
+
+        WireId cursor = dst;
+
+        std::vector<PipId> to_bind;
+
+        while (cursor != src) {
+            if (!ctx->checkWireAvail(cursor)) {
+                NetInfo *bound_net = ctx->getBoundWireNet(cursor);
+                if (bound_net != net) {
+                    if (ctx->verbose) {
+                        if (bound_net != nullptr) {
+                            log_info("Failed to bind wire %s to net %s, bound to net %s\n", ctx->nameOfWire(cursor),
+                                     net->name.c_str(ctx), bound_net->name.c_str(ctx));
+                        } else {
+                            log_info("Failed to bind wire %s to net %s, bound net nullptr\n", ctx->nameOfWire(cursor),
+                                     net->name.c_str(ctx));
+                        }
+                    }
+                    success = false;
+                    break;
+                }
+            }
+            if (!nd.wires.count(cursor)) {
+                log("Failure details:\n");
+                log("    Cursor: %s\n", ctx->nameOfWire(cursor));
+                log_error("Internal error; incomplete route tree for arc %d of net %s.\n", usr_idx.idx(),
+                          ctx->nameOf(net));
+            }
+            PipId p = nd.wires.at(cursor).first;
+            if (ctx->checkPipAvailForNet(p, net)) {
+                NetInfo *bound_net = ctx->getBoundPipNet(p);
+                if (bound_net == nullptr) {
+                    to_bind.push_back(p);
+                }
+            } else {
+                if (ctx->verbose) {
+                    log_info("Failed to bind pip %s to net %s\n", ctx->nameOfPip(p), net->name.c_str(ctx));
+                }
+                success = false;
+                break;
+            }
+            cursor = ctx->getPipSrcWire(p);
+        }
+
+        if (success) {
+            if (ctx->getBoundWireNet(src) == nullptr)
+                ctx->bindWire(src, net, STRENGTH_WEAK);
+            for (auto tb : to_bind)
+                ctx->bindPip(tb, net, STRENGTH_WEAK);
+        } else {
+            ripup_arc(net, usr_idx, phys_pin);
+            failed_nets.insert(net->udata);
+        }
+        return success;
+    }
+
+    int arch_fail = 0;
+    bool bind_and_check_all()
+    {
+        // Make sure arch is internally consistent before we mess with it.
+        ctx->check();
+
+        bool success = true;
+        std::vector<WireId> net_wires;
+        for (auto net : nets_by_udata) {
+#ifdef ARCH_ECP5
+            if (net->is_global)
+                continue;
+#endif
+            // Ripup wires and pips used by the net in nextpnr's structures
+            net_wires.clear();
+            for (auto &w : net->wires) {
+                if (w.second.strength <= STRENGTH_STRONG) {
+                    net_wires.push_back(w.first);
+                } else if (ctx->debug) {
+                    log("Net %s didn't rip up wire %s because strength was %d\n", ctx->nameOf(net),
+                        ctx->nameOfWire(w.first), w.second.strength);
+                }
+            }
+            for (auto w : net_wires)
+                ctx->unbindWire(w);
+
+            if (ctx->debug) {
+                log("Ripped up %zu wires on net %s\n", net_wires.size(), ctx->nameOf(net));
+            }
+
+            // Bind the arcs using the routes we have discovered
+            for (auto usr : net->users.enumerate()) {
+                for (size_t phys_pin = 0; phys_pin < nets.at(net->udata).arcs.at(usr.index.idx()).size(); phys_pin++) {
+                    if (!bind_and_check(net, usr.index, phys_pin)) {
+                        ++arch_fail;
+                        success = false;
+                    }
+                }
+            }
+        }
+
+        // Check that the arch is still internally consistent!
+        ctx->check();
+
+        return success;
+    }
+
+    void write_wiretype_heatmap(std::ostream &out)
+    {
+        dict<IdString, std::vector<int>> cong_by_type;
+        size_t max_cong = 0;
+        // Build histogram
+        for (auto &wd : flat_wires) {
+            size_t val = wd.curr_cong;
+            IdString type = ctx->getWireType(wd.w);
+            max_cong = std::max(max_cong, val);
+            if (cong_by_type[type].size() <= max_cong)
+                cong_by_type[type].resize(max_cong + 1);
+            cong_by_type[type].at(val) += 1;
+        }
+        // Write csv
+        out << "type,";
+        for (size_t i = 0; i <= max_cong; i++)
+            out << "bound=" << i << ",";
+        out << std::endl;
+        for (auto &ty : cong_by_type) {
+            out << ctx->nameOf(ty.first) << ",";
+            for (int count : ty.second)
+                out << count << ",";
+            out << std::endl;
+        }
+    }
+
+    int mid_x = 0, mid_y = 0;
+
+    void partition_nets()
+    {
+        // Create a histogram of positions in X and Y positions
+        std::map<int, int> cxs, cys;
+        for (auto &n : nets) {
+            if (n.cx != -1)
+                ++cxs[n.cx];
+            if (n.cy != -1)
+                ++cys[n.cy];
+        }
+        // 4-way split for now
+        int accum_x = 0, accum_y = 0;
+        int halfway = int(nets.size()) / 2;
+        for (auto &p : cxs) {
+            if (accum_x < halfway && (accum_x + p.second) >= halfway)
+                mid_x = p.first;
+            accum_x += p.second;
+        }
+        for (auto &p : cys) {
+            if (accum_y < halfway && (accum_y + p.second) >= halfway)
+                mid_y = p.first;
+            accum_y += p.second;
+        }
+        if (ctx->verbose) {
+            log_info("    x splitpoint: %d\n", mid_x);
+            log_info("    y splitpoint: %d\n", mid_y);
+        }
+        std::vector<int> bins(5, 0);
+        for (auto &n : nets) {
+            if (n.bb.x0 < mid_x && n.bb.x1 < mid_x && n.bb.y0 < mid_y && n.bb.y1 < mid_y)
+                ++bins[0]; // TL
+            else if (n.bb.x0 >= mid_x && n.bb.x1 >= mid_x && n.bb.y0 < mid_y && n.bb.y1 < mid_y)
+                ++bins[1]; // TR
+            else if (n.bb.x0 < mid_x && n.bb.x1 < mid_x && n.bb.y0 >= mid_y && n.bb.y1 >= mid_y)
+                ++bins[2]; // BL
+            else if (n.bb.x0 >= mid_x && n.bb.x1 >= mid_x && n.bb.y0 >= mid_y && n.bb.y1 >= mid_y)
+                ++bins[3]; // BR
+            else
+                ++bins[4]; // cross-boundary
+        }
+        if (ctx->verbose)
+            for (int i = 0; i < 5; i++)
+                log_info("        bin %d N=%d\n", i, bins[i]);
+    }
+
+    void router_thread(ThreadContext &t, bool is_mt)
+    {
+        for (auto n : t.route_nets) {
+            bool result = route_net(t, n, is_mt);
+            if (!result)
+                t.failed_nets.push_back(n);
+        }
+    }
+
+    void do_route()
+    {
+        // Don't multithread if fewer than 200 nets (heuristic)
+        if (route_queue.size() < 200) {
+            ThreadContext st;
+            st.rng.rngseed(ctx->rng64());
+            st.bb = ArcBounds(0, 0, std::numeric_limits<int>::max(), std::numeric_limits<int>::max());
+            for (size_t j = 0; j < route_queue.size(); j++) {
+                route_net(st, nets_by_udata[route_queue[j]], false);
+            }
+            return;
+        }
+        const int Nq = 4, Nv = 2, Nh = 2;
+        const int N = Nq + Nv + Nh;
+        std::vector<ThreadContext> tcs(N + 1);
+        for (auto &th : tcs) {
+            th.rng.rngseed(ctx->rng64());
+        }
+        int le_x = mid_x;
+        int rs_x = mid_x;
+        int le_y = mid_y;
+        int rs_y = mid_y;
+        // Set up thread bounding boxes
+        tcs.at(0).bb = ArcBounds(0, 0, mid_x, mid_y);
+        tcs.at(1).bb = ArcBounds(mid_x + 1, 0, std::numeric_limits<int>::max(), le_y);
+        tcs.at(2).bb = ArcBounds(0, mid_y + 1, mid_x, std::numeric_limits<int>::max());
+        tcs.at(3).bb =
+                ArcBounds(mid_x + 1, mid_y + 1, std::numeric_limits<int>::max(), std::numeric_limits<int>::max());
+
+        tcs.at(4).bb = ArcBounds(0, 0, std::numeric_limits<int>::max(), mid_y);
+        tcs.at(5).bb = ArcBounds(0, mid_y + 1, std::numeric_limits<int>::max(), std::numeric_limits<int>::max());
+
+        tcs.at(6).bb = ArcBounds(0, 0, mid_x, std::numeric_limits<int>::max());
+        tcs.at(7).bb = ArcBounds(mid_x + 1, 0, std::numeric_limits<int>::max(), std::numeric_limits<int>::max());
+
+        tcs.at(8).bb = ArcBounds(0, 0, std::numeric_limits<int>::max(), std::numeric_limits<int>::max());
+
+        for (auto n : route_queue) {
+            auto &nd = nets.at(n);
+            auto ni = nets_by_udata.at(n);
+            int bin = N;
+            // Quadrants
+            if (nd.bb.x0 < le_x && nd.bb.x1 < le_x && nd.bb.y0 < le_y && nd.bb.y1 < le_y)
+                bin = 0;
+            else if (nd.bb.x0 >= rs_x && nd.bb.x1 >= rs_x && nd.bb.y0 < le_y && nd.bb.y1 < le_y)
+                bin = 1;
+            else if (nd.bb.x0 < le_x && nd.bb.x1 < le_x && nd.bb.y0 >= rs_y && nd.bb.y1 >= rs_y)
+                bin = 2;
+            else if (nd.bb.x0 >= rs_x && nd.bb.x1 >= rs_x && nd.bb.y0 >= rs_y && nd.bb.y1 >= rs_y)
+                bin = 3;
+            // Vertical split
+            else if (nd.bb.y0 < le_y && nd.bb.y1 < le_y)
+                bin = Nq + 0;
+            else if (nd.bb.y0 >= rs_y && nd.bb.y1 >= rs_y)
+                bin = Nq + 1;
+            // Horizontal split
+            else if (nd.bb.x0 < le_x && nd.bb.x1 < le_x)
+                bin = Nq + Nv + 0;
+            else if (nd.bb.x0 >= rs_x && nd.bb.x1 >= rs_x)
+                bin = Nq + Nv + 1;
+            tcs.at(bin).route_nets.push_back(ni);
+        }
+        if (ctx->verbose)
+            log_info("%d/%d nets not multi-threadable\n", int(tcs.at(N).route_nets.size()), int(route_queue.size()));
+#ifdef NPNR_DISABLE_THREADS
+        // Singlethreaded routing - quadrants
+        for (int i = 0; i < Nq; i++) {
+            router_thread(tcs.at(i), /*is_mt=*/false);
+        }
+        // Vertical splits
+        for (int i = Nq; i < Nq + Nv; i++) {
+            router_thread(tcs.at(i), /*is_mt=*/false);
+        }
+        // Horizontal splits
+        for (int i = Nq + Nv; i < Nq + Nv + Nh; i++) {
+            router_thread(tcs.at(i), /*is_mt=*/false);
+        }
+#else
+        // Multithreaded part of routing - quadrants
+        std::vector<boost::thread> threads;
+        for (int i = 0; i < Nq; i++) {
+            threads.emplace_back([this, &tcs, i]() { router_thread(tcs.at(i), /*is_mt=*/true); });
+        }
+        for (auto &t : threads)
+            t.join();
+        threads.clear();
+        // Vertical splits
+        for (int i = Nq; i < Nq + Nv; i++) {
+            threads.emplace_back([this, &tcs, i]() { router_thread(tcs.at(i), /*is_mt=*/true); });
+        }
+        for (auto &t : threads)
+            t.join();
+        threads.clear();
+        // Horizontal splits
+        for (int i = Nq + Nv; i < Nq + Nv + Nh; i++) {
+            threads.emplace_back([this, &tcs, i]() { router_thread(tcs.at(i), /*is_mt=*/true); });
+        }
+        for (auto &t : threads)
+            t.join();
+        threads.clear();
+#endif
+        // Singlethreaded part of routing - nets that cross partitions
+        // or don't fit within bounding box
+        for (auto st_net : tcs.at(N).route_nets)
+            route_net(tcs.at(N), st_net, false);
+        // Failed nets
+        for (int i = 0; i < N; i++)
+            for (auto fail : tcs.at(i).failed_nets)
+                route_net(tcs.at(N), fail, false);
+    }
+
+    delay_t get_route_delay(int net, store_index<PortRef> usr_idx, int phys_idx)
+    {
+        auto &nd = nets.at(net);
+        auto &ad = nd.arcs.at(usr_idx.idx()).at(phys_idx);
+        WireId cursor = ad.sink_wire;
+        if (cursor == WireId() || nd.src_wire == WireId())
+            return 0;
+        delay_t delay = 0;
+        while (true) {
+            delay += ctx->getWireDelay(cursor).maxDelay();
+            if (!nd.wires.count(cursor))
+                break;
+            auto &bound = nd.wires.at(cursor);
+            if (bound.first == PipId())
+                break;
+            delay += ctx->getPipDelay(bound.first).maxDelay();
+            cursor = ctx->getPipSrcWire(bound.first);
+        }
+        NPNR_ASSERT(cursor == nd.src_wire);
+        return delay;
+    }
+
+    void update_route_delays()
+    {
+        for (int net : route_queue) {
+            NetInfo *ni = nets_by_udata.at(net);
+#ifdef ARCH_ECP5
+            if (ni->is_global)
+                continue;
+#endif
+            auto &nd = nets.at(net);
+            for (auto usr : ni->users.enumerate()) {
+                delay_t arc_delay = 0;
+                for (int j = 0; j < int(nd.arcs.at(usr.index.idx()).size()); j++)
+                    arc_delay = std::max(arc_delay, get_route_delay(net, usr.index, j));
+                tmg.set_route_delay(CellPortKey(usr.value), DelayPair(arc_delay));
+            }
+        }
+    }
+
+    void operator()()
+    {
+        log_info("Running router2...\n");
+        log_info("Setting up routing resources...\n");
+        auto rstart = std::chrono::high_resolution_clock::now();
+        setup_nets();
+        setup_wires();
+        find_all_reserved_wires();
+        partition_nets();
+        curr_cong_weight = cfg.init_curr_cong_weight;
+        hist_cong_weight = cfg.hist_cong_weight;
+        ThreadContext st;
+        int iter = 1;
+
+        ScopeLock<Context> lock(ctx);
+
+        for (size_t i = 0; i < nets_by_udata.size(); i++)
+            route_queue.push_back(i);
+
+        timing_driven = ctx->setting<bool>("timing_driven");
+        if (ctx->settings.count(ctx->id("router/tmg_ripup")))
+            timing_driven_ripup = timing_driven && ctx->setting<bool>("router/tmg_ripup");
+        else
+            timing_driven_ripup = false;
+        log_info("Running main router loop...\n");
+        if (timing_driven)
+            tmg.run(true);
+        do {
+            ctx->sorted_shuffle(route_queue);
+
+            if (timing_driven && int(route_queue.size()) >= 30) {
+                for (auto n : route_queue) {
+                    NetInfo *ni = nets_by_udata.at(n);
+                    auto &net = nets.at(n);
+                    net.max_crit = 0;
+                    for (auto &usr : ni->users) {
+                        float c = tmg.get_criticality(CellPortKey(usr));
+                        net.max_crit = std::max(net.max_crit, c);
+                    }
+                }
+                std::stable_sort(route_queue.begin(), route_queue.end(),
+                                 [&](int na, int nb) { return nets.at(na).max_crit > nets.at(nb).max_crit; });
+            }
+
+            do_route();
+            update_route_delays();
+            route_queue.clear();
+            update_congestion();
+
+            if (!cfg.heatmap.empty()) {
+                std::string filename(cfg.heatmap + "_" + std::to_string(iter) + ".csv");
+                std::ofstream cong_map(filename);
+                if (!cong_map)
+                    log_error("Failed to open wiretype heatmap %s for writing.\n", filename.c_str());
+                write_wiretype_heatmap(cong_map);
+                log_info("        wrote wiretype heatmap to %s.\n", filename.c_str());
+            }
+            int tmgfail = 0;
+            if (timing_driven)
+                tmg.run(false);
+            if (timing_driven_ripup && iter < 500) {
+                for (size_t i = 0; i < nets_by_udata.size(); i++) {
+                    NetInfo *ni = nets_by_udata.at(i);
+                    for (auto usr : ni->users.enumerate()) {
+                        if (arc_failed_slack(ni, usr.index)) {
+                            failed_nets.insert(i);
+                            ++tmgfail;
+                        }
+                    }
+                }
+            }
+            if (overused_wires == 0 && tmgfail == 0) {
+                // Try and actually bind nextpnr Arch API wires
+                bind_and_check_all();
+            }
+            for (auto cn : failed_nets)
+                route_queue.push_back(cn);
+            if (timing_driven_ripup)
+                log_info("    iter=%d wires=%d overused=%d overuse=%d tmgfail=%d archfail=%s\n", iter, total_wire_use,
+                         overused_wires, total_overuse, tmgfail,
+                         (overused_wires > 0 || tmgfail > 0) ? "NA" : std::to_string(arch_fail).c_str());
+            else
+                log_info("    iter=%d wires=%d overused=%d overuse=%d archfail=%s\n", iter, total_wire_use,
+                         overused_wires, total_overuse,
+                         (overused_wires > 0 || tmgfail > 0) ? "NA" : std::to_string(arch_fail).c_str());
+            ++iter;
+            if (curr_cong_weight < 1e9)
+                curr_cong_weight += cfg.curr_cong_mult;
+        } while (!failed_nets.empty());
+        if (cfg.perf_profile) {
+            std::vector<std::pair<int, IdString>> nets_by_runtime;
+            for (auto &n : nets_by_udata) {
+                nets_by_runtime.emplace_back(nets.at(n->udata).total_route_us, n->name);
+            }
+            std::sort(nets_by_runtime.begin(), nets_by_runtime.end(), std::greater<std::pair<int, IdString>>());
+            log_info("1000 slowest nets by runtime:\n");
+            for (int i = 0; i < std::min(int(nets_by_runtime.size()), 1000); i++) {
+                log("        %80s %6d %.1fms\n", nets_by_runtime.at(i).second.c_str(ctx),
+                    int(ctx->nets.at(nets_by_runtime.at(i).second)->users.entries()),
+                    nets_by_runtime.at(i).first / 1000.0);
+            }
+        }
+        auto rend = std::chrono::high_resolution_clock::now();
+        log_info("Router2 time %.02fs\n", std::chrono::duration<float>(rend - rstart).count());
+
+        log_info("Running router1 to check that route is legal...\n");
+
+        lock.unlock_early();
+
+        router1(ctx, Router1Cfg(ctx));
+    }
+};
+} // namespace
+
+void router2(Context *ctx, const Router2Cfg &cfg)
+{
+    Router2 rt(ctx, cfg);
+    rt.ctx = ctx;
+    rt();
+}
+
+Router2Cfg::Router2Cfg(Context *ctx)
+{
+    backwards_max_iter = ctx->setting<int>("router2/bwdMaxIter", 20);
+    global_backwards_max_iter = ctx->setting<int>("router2/glbBwdMaxIter", 200);
+    bb_margin_x = ctx->setting<int>("router2/bbMargin/x", 3);
+    bb_margin_y = ctx->setting<int>("router2/bbMargin/y", 3);
+    ipin_cost_adder = ctx->setting<float>("router2/ipinCostAdder", 0.0f);
+    bias_cost_factor = ctx->setting<float>("router2/biasCostFactor", 0.25f);
+    init_curr_cong_weight = ctx->setting<float>("router2/initCurrCongWeight", 0.5f);
+    hist_cong_weight = ctx->setting<float>("router2/histCongWeight", 1.0f);
+    curr_cong_mult = ctx->setting<float>("router2/currCongWeightMult", 2.0f);
+    estimate_weight = ctx->setting<float>("router2/estimateWeight", 1.25f);
+    perf_profile = ctx->setting<bool>("router2/perfProfile", false);
+    if (ctx->settings.count(ctx->id("router2/heatmap")))
+        heatmap = ctx->settings.at(ctx->id("router2/heatmap")).as_string();
+    else
+        heatmap = "";
+}
+
+NEXTPNR_NAMESPACE_END
diff --git a/common/route/router2.h b/common/route/router2.h
new file mode 100644
index 00000000..629453c6
--- /dev/null
+++ b/common/route/router2.h
@@ -0,0 +1,66 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2019  gatecat <gatecat@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 "nextpnr.h"
+
+NEXTPNR_NAMESPACE_BEGIN
+
+inline float default_base_cost(Context *ctx, WireId wire, PipId pip, float crit_weight)
+{
+    (void)crit_weight; // unused
+    return ctx->getDelayNS(ctx->getPipDelay(pip).maxDelay() + ctx->getWireDelay(wire).maxDelay() +
+                           ctx->getDelayEpsilon());
+}
+
+struct Router2Cfg
+{
+    Router2Cfg(Context *ctx);
+
+    // Maximum iterations for backwards routing attempt
+    int backwards_max_iter;
+    // Maximum iterations for backwards routing attempt for global nets
+    int global_backwards_max_iter;
+    // Padding added to bounding boxes to account for imperfect routing,
+    // congestion, etc
+    int bb_margin_x, bb_margin_y;
+    // Cost factor added to input pin wires; effectively reduces the
+    // benefit of sharing interconnect
+    float ipin_cost_adder;
+    // Cost factor for "bias" towards center location of net
+    float bias_cost_factor;
+    // Starting current and historical congestion cost factor
+    float init_curr_cong_weight, hist_cong_weight;
+    // Current congestion cost multiplier
+    float curr_cong_mult;
+
+    // Weight given to delay estimate in A*. Higher values
+    // mean faster and more directed routing, at the risk
+    // of choosing a less congestion/delay-optimal route
+    float estimate_weight;
+
+    // Print additional performance profiling information
+    bool perf_profile = false;
+
+    std::string heatmap;
+    std::function<float(Context *ctx, WireId wire, PipId pip, float crit_weight)> get_base_cost = default_base_cost;
+};
+
+void router2(Context *ctx, const Router2Cfg &cfg);
+
+NEXTPNR_NAMESPACE_END