router2: Add a cleanup pass between iterations
Signed-off-by: gatecat <gatecat@ds0.me>
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gatecat
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9b51c6e337
commit
974ed04f9b
@ -1025,6 +1025,120 @@ struct Router2
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}
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}
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int trim_routing(NetInfo *net)
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{
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// Find places where we have a cheaper way of reaching a wire from earlier in the route tree
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// and rewrite routing trees to use those cheaper routes.
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int cleaned = 0;
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#ifdef ARCH_ECP5
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if (net->is_global)
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return 0;
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#endif
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// Build a reverse of the wires map going downhill
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auto &nd = nets.at(net->udata);
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dict<WireId, pool<PipId>> src2pips;
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pool<WireId> sources;
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for (const auto &wire : nd.wires) {
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PipId pip = wire.second.first;
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if (pip == PipId()) {
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sources.insert(wire.first);
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} else {
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src2pips[ctx->getPipSrcWire(pip)].insert(pip);
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}
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}
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// Compute depths of wires in the route tree for a net
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dict<WireId, int> depth;
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auto update_depth = [&](WireId src, int src_depth) {
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std::queue<std::pair<WireId, int>> visit;
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visit.emplace(src, src_depth + 1);
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depth[src] = src_depth;
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while (!visit.empty()) {
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auto cursor = visit.front();
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visit.pop();
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if (!src2pips.count(cursor.first))
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continue;
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for (PipId dh : src2pips.at(cursor.first)) {
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WireId dst = ctx->getPipDstWire(dh);
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depth[dst] = cursor.second;
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visit.emplace(dst, cursor.second + 1);
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}
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}
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};
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for (WireId src : sources) {
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update_depth(src, 0);
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}
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pool<WireId> touched;
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for (auto entry : depth) {
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// Check it wasn't removed by a previous prune
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if (nd.wires.at(entry.first).second == 0)
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continue;
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// Find cheaper route
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PipId best;
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int score = entry.second;
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for (PipId pip : ctx->getPipsUphill(entry.first)) {
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if (!ctx->checkPipAvailForNet(pip, net))
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continue;
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WireId src = ctx->getPipSrcWire(pip);
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auto fnd_depth = depth.find(src);
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if (fnd_depth == depth.end())
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continue;
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if ((fnd_depth->second + 1) < score) {
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if (ctx->debug) {
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log_info(" found cheaper route to '%s' (%d) from '%s' (%d) on net '%s'\n",
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ctx->nameOfWire(entry.first), entry.second, ctx->nameOfWire(src), fnd_depth->second, ctx->nameOf(net));
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}
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score = fnd_depth->second + 1;
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best = pip;
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}
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}
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if (best != PipId()) {
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cleaned++;
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WireId new_src = ctx->getPipSrcWire(best);
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// Transplant the route tree on top of the cheaper pip
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auto &dst_entry = nd.wires.at(entry.first);
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// Add new routing
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WireId cursor = new_src;
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while (true) {
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auto &entry = nd.wires.at(cursor);
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entry.second += dst_entry.second;
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if (entry.first != PipId()) {
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cursor = ctx->getPipSrcWire(entry.first);
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} else {
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break;
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}
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}
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// Remove old routing
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cursor = ctx->getPipSrcWire(dst_entry.first);
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src2pips[cursor].erase(dst_entry.first);
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while (true) {
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auto &entry = nd.wires.at(cursor);
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entry.second -= dst_entry.second;
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NPNR_ASSERT(entry.second >= 0);
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touched.insert(cursor);
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if (entry.first != PipId()) {
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cursor = ctx->getPipSrcWire(entry.first);
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} else {
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break;
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}
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}
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// Rewrite tree
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dst_entry.first = best;
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src2pips[new_src].insert(best);
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update_depth(entry.first, score);
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}
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}
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for (WireId wire : touched) {
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auto &entry = nd.wires.at(wire);
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if (entry.second == 0) {
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nd.wires.erase(wire);
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--wire_data(wire).curr_cong;
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}
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}
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return cleaned;
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}
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bool bind_and_check(NetInfo *net, store_index<PortRef> usr_idx, int phys_pin)
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{
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#ifdef ARCH_ECP5
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@ -1372,6 +1486,10 @@ struct Router2
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delay += ctx->getPipDelay(bound.first).maxDelay();
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cursor = ctx->getPipSrcWire(bound.first);
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}
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if (cursor != nd.src_wire) {
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log_info("net %s got src %s expected src %s\n",
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ctx->nameOf(nets_by_udata.at(net)), ctx->nameOfWire(cursor), ctx->nameOfWire(nd.src_wire));
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}
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NPNR_ASSERT(cursor == nd.src_wire);
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return delay;
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}
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@ -1439,6 +1557,10 @@ struct Router2
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}
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do_route();
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int cleaned = 0;
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for (auto n : route_queue) {
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cleaned += trim_routing(nets_by_udata.at(n));
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}
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update_route_delays();
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route_queue.clear();
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update_congestion();
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@ -1472,12 +1594,12 @@ struct Router2
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for (auto cn : failed_nets)
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route_queue.push_back(cn);
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if (timing_driven_ripup)
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log_info(" iter=%d wires=%d overused=%d overuse=%d tmgfail=%d archfail=%s\n", iter, total_wire_use,
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overused_wires, total_overuse, tmgfail,
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log_info(" iter=%d wires=%d overused=%d overuse=%d tmgfail=%d cleanedup=%d archfail=%s\n", iter, total_wire_use,
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overused_wires, total_overuse, tmgfail, cleaned,
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(overused_wires > 0 || tmgfail > 0) ? "NA" : std::to_string(arch_fail).c_str());
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else
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log_info(" iter=%d wires=%d overused=%d overuse=%d archfail=%s\n", iter, total_wire_use,
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overused_wires, total_overuse,
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log_info(" iter=%d wires=%d overused=%d overuse=%d cleanedup=%d archfail=%s\n", iter, total_wire_use,
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overused_wires, total_overuse, cleaned,
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(overused_wires > 0 || tmgfail > 0) ? "NA" : std::to_string(arch_fail).c_str());
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++iter;
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if (curr_cong_weight < 1e9)
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