Add crude histogram feature, printed after placement and routing
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85a436198c
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@ -933,7 +933,7 @@ bool router1(Context *ctx, const Router1Cfg &cfg)
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#ifndef NDEBUG
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ctx->check();
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#endif
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timing_analysis(ctx, true /* print_path */);
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timing_analysis(ctx, true /* slack_histogram */, true /* print_path */);
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ctx->unlock();
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return true;
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} catch (log_execution_error_exception) {
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@ -27,6 +27,7 @@
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NEXTPNR_NAMESPACE_BEGIN
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typedef std::vector<const PortRef*> PortRefVector;
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typedef std::map<delay_t, unsigned> DelayFrequency;
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struct Timing
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{
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@ -35,8 +36,10 @@ struct Timing
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delay_t min_slack;
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PortRefVector current_path;
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PortRefVector *crit_path;
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DelayFrequency *slack_histogram;
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Timing(Context *ctx, bool update, PortRefVector *crit_path = nullptr): ctx(ctx), update(update), min_slack(1.0e12 / ctx->target_freq), crit_path(crit_path) {}
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Timing(Context *ctx, bool update, PortRefVector *crit_path = nullptr, DelayFrequency *slack_histogram = nullptr)
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: ctx(ctx), update(update), min_slack(1.0e12 / ctx->target_freq), crit_path(crit_path), slack_histogram(slack_histogram) {}
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delay_t follow_net(NetInfo *net, int path_length, delay_t slack)
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{
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@ -75,6 +78,8 @@ struct Timing
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if (crit_path)
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*crit_path = current_path;
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}
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if (slack_histogram)
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(*slack_histogram)[slack]++;
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} else {
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// Default to the path ending here, if no further paths found
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value = slack / path_length;
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@ -178,11 +183,12 @@ void assign_budget(Context *ctx, bool quiet)
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log_info("Checksum: 0x%08x\n", ctx->checksum());
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}
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void timing_analysis(Context *ctx, bool print_path)
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void timing_analysis(Context *ctx, bool print_histogram, bool print_path)
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{
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PortRefVector crit_path;
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DelayFrequency slack_histogram;
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Timing timing(ctx, false /* update */, &crit_path);
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Timing timing(ctx, false /* update */, print_path ? &crit_path : nullptr, print_histogram ? &slack_histogram : nullptr);
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auto min_slack = timing.walk_paths();
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if (print_path) {
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@ -224,6 +230,28 @@ void timing_analysis(Context *ctx, bool print_path)
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delay_t default_slack = delay_t(1.0e12 / ctx->target_freq);
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log_info("estimated Fmax = %.2f MHz\n", 1e6 / (default_slack - min_slack));
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if (print_histogram) {
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constexpr unsigned num_bins = 20;
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unsigned bar_width = 60;
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auto min_slack = slack_histogram.begin()->first;
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auto max_slack = slack_histogram.rbegin()->first;
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auto bin_size = (max_slack - min_slack) / num_bins;
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std::vector<unsigned> bins(num_bins+1);
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unsigned max_freq = 0;
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for (const auto& i : slack_histogram) {
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auto& bin = bins[(i.first-min_slack) / bin_size];
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bin += i.second;
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max_freq = std::max(max_freq, bin);
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}
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bar_width = std::min(bar_width, max_freq);
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log_break();
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log_info("Slack histogram:\n");
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log_info(" legend: * represents %d endpoint(s)\n", max_freq / bar_width);
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for (unsigned i = 0; i < bins.size(); ++i)
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log_info("%6d < ps < %6d |%s\n", min_slack + bin_size*i, min_slack + bin_size*(i+1), std::string(bins[i] * bar_width / max_freq, '*').c_str());
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}
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}
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NEXTPNR_NAMESPACE_END
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@ -29,7 +29,7 @@ void assign_budget(Context *ctx, bool quiet = false);
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// Perform timing analysis and print out the fmax, and optionally the
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// critical path
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void timing_analysis(Context *ctx, bool print_path = false);
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void timing_analysis(Context *ctx, bool slack_histogram = true, bool print_path = false);
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NEXTPNR_NAMESPACE_END
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