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router2: Add experimental timing-driven ripup option

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Signed-off-by: gatecat <gatecat@ds0.me>
This commit is contained in:
gatecat 2021-08-15 16:18:57 +01:00
parent 42522c492c
commit f207068ee2
3 changed files with 67 additions and 14 deletions
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4
common/command.cc
View File

@ -173,6 +173,8 @@ po::options_description CommandHandler::getGeneralOptions()
general.add_options()("router2-heatmap", po::value<std::string>(),
"prefix for router2 resource congestion heatmaps");
general.add_options()("router2-tmg-ripup", "enable experimental timing-driven ripup in router2");
general.add_options()("report", po::value<std::string>(),
"write timing and utilization report in JSON format to file");
@ -286,6 +288,8 @@ void CommandHandler::setupContext(Context *ctx)
ctx->settings[ctx->id("placerHeap/timingWeight")] = std::to_string(vm["placer-heap-timingweight"].as<int>());
if (vm.count("router2-heatmap"))
ctx->settings[ctx->id("router2/heatmap")] = vm["router2-heatmap"].as<std::string>();
if (vm.count("router2-tmg-ripup"))
ctx->settings[ctx->id("router2/tmg_ripup")] = true;
// Setting default values
if (ctx->settings.find(ctx->id("target_freq")) == ctx->settings.end())

56
common/router2.cc
View File

@ -104,7 +104,7 @@ struct Router2
std::vector<NetInfo *> nets_by_udata;
std::vector<PerNetData> nets;
bool timing_driven;
bool timing_driven, timing_driven_ripup;
TimingAnalyser tmg;
void setup_nets()
@ -358,7 +358,7 @@ struct Router2
float base_cost = ctx->getDelayNS(ctx->getPipDelay(pip).maxDelay() + ctx->getWireDelay(wire).maxDelay() +
ctx->getDelayEpsilon());
int overuse = wd.curr_cong;
float hist_cost = wd.hist_cong_cost;
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)) {
@ -574,6 +574,12 @@ struct Router2
return tmg.get_criticality(CellPortKey(net->users.at(i)));
}
bool arc_failed_slack(NetInfo *net, size_t 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, size_t i, size_t phys_pin, bool is_mt, bool is_bb = true)
{
// Do some initial lookups and checks
@ -595,6 +601,7 @@ struct Router2
// 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;
@ -603,7 +610,7 @@ struct Router2
// 0. starting within a small range of existing routing
// 1. expanding from all routing
int mode = 0;
if (net->users.size() < 4 || nd.wires.empty())
if (net->users.size() < 4 || nd.wires.empty() || (crit > 0.95))
mode = 1;
// This records the point where forwards and backwards routing met
@ -866,12 +873,15 @@ struct Router2
t.wire_by_loc.clear();
t.in_wire_by_loc.clear();
auto &nd = nets.at(net->udata);
bool failed_slack = false;
for (size_t i = 0; i < net->users.size(); i++)
failed_slack |= arc_failed_slack(net, i);
for (size_t i = 0; i < net->users.size(); i++) {
auto &ad = nd.arcs.at(i);
for (size_t j = 0; j < ad.size(); j++) {
// Ripup failed arcs to start with
// Check if arc is already legally routed
if (check_arc_routing(net, i, j)) {
if (!failed_slack && check_arc_routing(net, i, j)) {
update_wire_by_loc(t, net, i, j, true);
continue;
}
@ -1357,14 +1367,17 @@ struct Router2
route_queue.push_back(i);
timing_driven = ctx->setting<bool>("timing_driven");
if (ctx->settings.count(ctx->id("router2/tmg_ripup")))
timing_driven_ripup = timing_driven && ctx->setting<bool>("router2/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()) > (int(nets_by_udata.size()) / 500))) {
// Heuristic: reduce runtime by skipping STA in the case of a "long tail" of a few
// congested nodes
tmg.run(iter == 1);
if (timing_driven) {
for (auto n : route_queue) {
NetInfo *ni = nets_by_udata.at(n);
auto &net = nets.at(n);
@ -1391,15 +1404,34 @@ struct Router2
write_wiretype_heatmap(cong_map);
log_info(" wrote wiretype heatmap to %s.\n", filename.c_str());
}
if (overused_wires == 0) {
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 (size_t j = 0; j < ni->users.size(); j++) {
if (arc_failed_slack(ni, j)) {
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);
log_info(" iter=%d wires=%d overused=%d overuse=%d archfail=%s\n", iter, total_wire_use, overused_wires,
total_overuse, overused_wires > 0 ? "NA" : std::to_string(arch_fail).c_str());
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;

21
common/timing.cc
View File

@ -269,6 +269,22 @@ void TimingAnalyser::setup_port_domains()
// If there are loops, repeat the process until a fixed point is reached, as there might be unusual ways to
// visit points, which would result in a missing domain key and therefore crash later on
} while (have_loops && updated_domains);
for (auto &dp : domain_pairs) {
auto &launch_data = domains.at(dp.key.launch);
auto &capture_data = domains.at(dp.key.capture);
if (launch_data.key.clock != capture_data.key.clock)
continue;
IdString clk = launch_data.key.clock;
if (!ctx->nets.count(clk))
continue;
NetInfo *clk_net = ctx->nets.at(clk).get();
if (!clk_net->clkconstr)
continue;
delay_t period = clk_net->clkconstr->period.minDelay();
if (launch_data.key.edge != capture_data.key.edge)
period /= 2;
dp.period = DelayPair(period);
}
}
void TimingAnalyser::reset_times()
@ -457,11 +473,12 @@ void TimingAnalyser::compute_slack()
auto &dp = domain_pairs.at(pdp.first);
auto &arr = pd.arrival.at(dp.key.launch);
auto &req = pd.required.at(dp.key.capture);
pdp.second.setup_slack = dp.period.minDelay() - (arr.value.maxDelay() - req.value.minDelay());
pdp.second.setup_slack = 0 - (arr.value.maxDelay() - req.value.minDelay());
if (!setup_only)
pdp.second.hold_slack = arr.value.minDelay() - req.value.maxDelay();
pdp.second.max_path_length = arr.path_length + req.path_length;
pd.worst_setup_slack = std::min(pd.worst_setup_slack, pdp.second.setup_slack);
if (dp.key.launch == dp.key.capture)
pd.worst_setup_slack = std::min(pd.worst_setup_slack, dp.period.minDelay() + pdp.second.setup_slack);
dp.worst_setup_slack = std::min(dp.worst_setup_slack, pdp.second.setup_slack);
if (!setup_only) {
pd.worst_hold_slack = std::min(pd.worst_hold_slack, pdp.second.hold_slack);