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timing: Always split histogram with zero as a boundary #436

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timing: Always split histogram with zero as a boundary #436

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47 changes: 37 additions & 10 deletions common/timing.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -956,15 +956,42 @@ void timing_analysis(Context *ctx, bool print_histogram, bool print_fmax, bool p
if (print_histogram && slack_histogram.size() > 0) {
unsigned num_bins = 20;
unsigned bar_width = 60;
std::vector<unsigned> bins_count(num_bins);
std::vector<unsigned> bins_bounds(num_bins + 1);
unsigned max_freq = 0;
auto min_slack = slack_histogram.begin()->first;
auto max_slack = slack_histogram.rbegin()->first;
auto bin_size = std::max<unsigned>(1, ceil((max_slack - min_slack + 1) / float(num_bins)));
std::vector<unsigned> bins(num_bins);
unsigned max_freq = 0;
for (const auto &i : slack_histogram) {
auto &bin = bins[(i.first - min_slack) / bin_size];
bin += i.second;
max_freq = std::max(max_freq, bin);

if ((min_slack < 0) && (max_slack > 0)) {
/* Double sided histogram */
/* [0...bin_ofs-1] = neg */
/* [bin_ofs...num_bins-1] = pos */
auto bin_ofs = std::max<unsigned>(
num_bins / 4, std::min<unsigned>(num_bins - (num_bins / 4) - 1,
ceil(float(num_bins) * -min_slack / (max_slack - min_slack))));
auto bin_size_neg = std::max<unsigned>(1, ceil((-min_slack + 1) / float(bin_ofs)));
auto bin_size_pos = std::max<unsigned>(1, ceil((max_slack + 1) / float(num_bins - bin_ofs)));
for (unsigned i = 0; i < bin_ofs; i++)
bins_bounds[i] = (i - bin_ofs) * bin_size_neg;
for (unsigned i = bin_ofs; i <= num_bins; i++)
bins_bounds[i] = (i - bin_ofs) * bin_size_pos;
for (const auto &i : slack_histogram) {
int idx = (i.first < 0) ? (int)bin_ofs + (i.first / (int)bin_size_neg) - 1
: (int)bin_ofs + (i.first / (int)bin_size_pos);
auto &bin = bins_count[idx];
bin += i.second;
max_freq = std::max(max_freq, bin);
}
} else {
/* Single sided histogram */
auto bin_size = std::max<unsigned>(1, ceil((max_slack - min_slack + 1) / float(num_bins)));
for (unsigned i = 0; i <= num_bins; i++)
bins_bounds[i] = min_slack + bin_size * i;
for (const auto &i : slack_histogram) {
auto &bin = bins_count[(i.first - min_slack) / bin_size];
bin += i.second;
max_freq = std::max(max_freq, bin);
}
}
bar_width = std::min(bar_width, max_freq);

Expand All @@ -973,9 +1000,9 @@ void timing_analysis(Context *ctx, bool print_histogram, bool print_fmax, bool p
log_info(" legend: * represents %d endpoint(s)\n", max_freq / bar_width);
log_info(" + represents [1,%d) endpoint(s)\n", max_freq / bar_width);
for (unsigned i = 0; i < num_bins; ++i)
log_info("[%6d, %6d) |%s%c\n", min_slack + bin_size * i, min_slack + bin_size * (i + 1),
std::string(bins[i] * bar_width / max_freq, '*').c_str(),
(bins[i] * bar_width) % max_freq > 0 ? '+' : ' ');
log_info("[%6d, %6d) | %6d | %s%c\n", bins_bounds[i], bins_bounds[i + 1], bins_count[i],
std::string(bins_count[i] * bar_width / max_freq, '*').c_str(),
(bins_count[i] * bar_width) % max_freq > 0 ? '+' : ' ');
}
}

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