interchange: Initial global routing implementation
Signed-off-by: gatecat <gatecat@ds0.me>
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@ -479,6 +479,24 @@ IdString Arch::getWireType(WireId wire) const
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return IdString(chip_info->wire_types[wire_type].name);
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}
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WireCategory Arch::get_wire_category(WireId wire) const
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{
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int tile = wire.tile, index = wire.index;
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if (tile == -1) {
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// Nodal wire
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const TileWireRefPOD &wr = chip_info->nodes[wire.index].tile_wires[0];
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tile = wr.tile;
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index = wr.index;
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}
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auto &w2t = chip_info->tiles[tile].tile_wire_to_type;
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if (index >= w2t.ssize())
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return WIRE_CAT_GENERAL;
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int wire_type = w2t[index];
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if (wire_type == -1)
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return WIRE_CAT_GENERAL;
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return WireCategory(chip_info->wire_types[wire_type].category);
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}
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std::vector<std::pair<IdString, std::string>> Arch::getWireAttrs(WireId wire) const { return {}; }
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// -----------------------------------------------------------------------
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@ -895,6 +913,8 @@ bool Arch::route()
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// terminate at a BEL pin.
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disallow_site_routing = true;
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route_globals();
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bool result;
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if (router == "router1") {
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result = router1(getCtx(), Router1Cfg(getCtx()));
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@ -533,6 +533,8 @@ struct Arch : ArchAPI<ArchRanges>
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return range;
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}
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WireCategory get_wire_category(WireId wire) const;
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// -------------------------------------------------
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PipId getPipByName(IdStringList name) const final;
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@ -686,6 +688,10 @@ struct Arch : ArchAPI<ArchRanges>
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std::unordered_set<CellInfo *> *placed_cells);
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void pack_ports();
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void decode_lut_cells();
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const GlobalCellPOD *global_cell_info(IdString cell_type) const;
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void route_globals();
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bool pack() final;
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bool place() final;
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bool route() final;
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196
fpga_interchange/globals.cc
Normal file
196
fpga_interchange/globals.cc
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@ -0,0 +1,196 @@
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/*
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* nextpnr -- Next Generation Place and Route
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*
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* Copyright (C) 2021 gatecat <gatecat@ds0.me>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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*/
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#include "log.h"
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#include "nextpnr.h"
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#include "util.h"
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#include <queue>
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NEXTPNR_NAMESPACE_BEGIN
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namespace {
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struct GlobalVist
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{
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PipId downhill = PipId();
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int total_hops = 0;
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int global_hops = 0;
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bool operator<(const GlobalVist &other) const
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{
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return (total_hops < other.total_hops) ||
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((total_hops == other.total_hops) && (global_hops > other.global_hops));
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}
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};
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static bool route_global_arc(Context *ctx, NetInfo *net, size_t usr_idx, size_t phys_port_idx, int max_hops)
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{
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auto &usr = net->users.at(usr_idx);
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WireId src = ctx->getNetinfoSourceWire(net);
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WireId dest = ctx->getNetinfoSinkWire(net, usr, phys_port_idx);
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if (dest == WireId()) {
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log_error("Arc %d.%d (%s.%s) of net %s has no sink wire!\n", int(usr_idx), int(phys_port_idx),
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ctx->nameOf(usr.cell), ctx->nameOf(usr.port), ctx->nameOf(net));
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}
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// Consider any existing routing put in place by the site router, etc
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int start_hops = 0;
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while (net->wires.count(dest) && dest != src) {
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dest = ctx->getPipSrcWire(net->wires.at(dest).pip);
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++start_hops;
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}
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// The main BFS implementation
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// Currently this is a backwards-BFS from sink to source (or pre-existing routing) that avoids general routing. It
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// currently aims for minimum hops as a primary goal and maximum global resource usage as a secondary goal. More
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// advanced heuristics will likely be needed for more complex situation
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WireId startpoint;
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GlobalVist best_visit;
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std::queue<WireId> visit_queue;
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std::unordered_map<WireId, GlobalVist> visits;
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visit_queue.push(dest);
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visits[dest].downhill = PipId();
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visits[dest].total_hops = start_hops;
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while (!visit_queue.empty()) {
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WireId cursor = visit_queue.front();
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visit_queue.pop();
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auto &curr_visit = visits.at(cursor);
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// We're now at least one layer deeper than a valid visit, any further exploration is futile
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if (startpoint != WireId() && curr_visit.total_hops > best_visit.total_hops)
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break;
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// Valid end of routing
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if ((cursor == src) || (ctx->getBoundWireNet(cursor) == net)) {
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if (startpoint == WireId() || curr_visit < best_visit) {
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startpoint = cursor;
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best_visit = curr_visit;
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}
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}
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// Explore uphill
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for (auto pip : ctx->getPipsUphill(cursor)) {
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if (!ctx->checkPipAvailForNet(pip, net))
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continue;
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WireId pip_src = ctx->getPipSrcWire(pip);
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if (!ctx->checkWireAvail(pip_src) && ctx->getBoundWireNet(pip_src) != net)
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continue;
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auto cat = ctx->get_wire_category(pip_src);
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if (cat == WIRE_CAT_GENERAL)
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continue; // never allow general routing
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GlobalVist next_visit;
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next_visit.downhill = pip;
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next_visit.total_hops = curr_visit.total_hops + 1;
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if (max_hops != -1 && next_visit.total_hops > max_hops)
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continue;
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next_visit.global_hops = curr_visit.global_hops + ((cat == WIRE_CAT_GLOBAL) ? 1 : 0);
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auto fnd_src = visits.find(pip_src);
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if (fnd_src == visits.end() || next_visit < fnd_src->second) {
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visit_queue.push(pip_src);
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visits[pip_src] = next_visit;
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}
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}
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}
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if (startpoint == WireId())
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return false;
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if (ctx->getBoundWireNet(startpoint) == nullptr)
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ctx->bindWire(startpoint, net, STRENGTH_LOCKED);
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WireId cursor = startpoint;
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std::vector<PipId> pips;
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// Create a list of pips on the routed path
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while (true) {
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PipId pip = visits.at(cursor).downhill;
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if (pip == PipId())
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break;
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pips.push_back(pip);
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cursor = ctx->getPipDstWire(pip);
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}
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// Reverse that list
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std::reverse(pips.begin(), pips.end());
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// Bind pips until we hit already-bound routing
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for (PipId pip : pips) {
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WireId dst = ctx->getPipDstWire(pip);
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if (ctx->getBoundWireNet(dst) == net)
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break;
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ctx->bindPip(pip, net, STRENGTH_LOCKED);
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}
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return true;
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}
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}; // namespace
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const GlobalCellPOD *Arch::global_cell_info(IdString cell_type) const
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{
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for (const auto &glb_cell : chip_info->global_cells)
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if (IdString(glb_cell.cell_type) == cell_type)
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return &glb_cell;
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return nullptr;
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}
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void Arch::route_globals()
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{
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log_info("Routing globals...\n");
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Context *ctx = getCtx();
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IdString gnd_net_name(chip_info->constants->gnd_net_name);
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IdString vcc_net_name(chip_info->constants->vcc_net_name);
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for (auto cell : sorted(ctx->cells)) {
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CellInfo *ci = cell.second;
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const GlobalCellPOD *glb_cell = global_cell_info(ci->type);
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if (glb_cell == nullptr)
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continue;
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for (const auto &pin : glb_cell->pins) {
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IdString pin_name(pin.name);
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if (!ci->ports.count(pin_name))
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continue;
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auto &port = ci->ports.at(pin_name);
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// TOOD: routing of input ports, too
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// output ports are generally the first priority though
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if (port.type != PORT_OUT)
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continue;
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NetInfo *net = port.net;
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if (net == nullptr || net->name == gnd_net_name || net->name == vcc_net_name)
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continue;
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int total_sinks = 0;
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int global_sinks = 0;
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for (size_t i = 0; i < net->users.size(); i++) {
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auto &usr = net->users.at(i);
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for (size_t j = 0; j < ctx->getNetinfoSinkWireCount(net, usr); j++) {
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bool routed_global = route_global_arc(ctx, net, i, j, pin.max_hops);
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++total_sinks;
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if (routed_global)
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++global_sinks;
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if (!routed_global && pin.force_routing)
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log_error("Failed to route arc %d.%d (%s.%s) of net %s using dedicated global routing!\n",
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int(i), int(j), ctx->nameOf(usr.cell), ctx->nameOf(usr.port), ctx->nameOf(net));
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}
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}
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log_info(" routed %d/%d sinks of net %s using dedicated routing.\n", global_sinks, total_sinks,
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ctx->nameOf(net));
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}
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}
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}
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NEXTPNR_NAMESPACE_END
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