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sta: very crude static timing analysis pass

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Co-authored-by: Eddie Hung <eddie@fpgeh.com>
This commit is contained in:
Lofty 2021-11-24 21:21:08 +00:00 • committed by Marcelina Kościelnicka
parent 113c943841
commit 77327b2544
9 changed files with 503 additions and 63 deletions
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1
passes/cmds/Makefile.inc
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@ -40,3 +40,4 @@ endif
OBJS += passes/cmds/scratchpad.o
OBJS += passes/cmds/logger.o
OBJS += passes/cmds/printattrs.o
OBJS += passes/cmds/sta.o

312
passes/cmds/sta.cc Normal file
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@ -0,0 +1,312 @@
/*
* yosys -- Yosys Open SYnthesis Suite
*
* Copyright (C) 2012 Clifford Wolf <clifford@clifford.at>
* (C) 2019 Eddie Hung <eddie@fpgeh.com>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#include "kernel/yosys.h"
#include "kernel/sigtools.h"
#include "kernel/timinginfo.h"
#include <deque>
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
struct StaWorker
{
Design *design;
Module *module;
SigMap sigmap;
struct t_data {
Cell* driver;
IdString dst_port, src_port;
vector<tuple<SigBit,int,IdString>> fanouts;
SigBit backtrack;
t_data() : driver(nullptr) {}
};
dict<SigBit, t_data> data;
std::deque<SigBit> queue;
struct t_endpoint {
Cell *sink;
IdString port;
int required;
t_endpoint() : sink(nullptr), required(0) {}
};
dict<SigBit, t_endpoint> endpoints;
int maxarrival;
SigBit maxbit;
pool<SigBit> driven;
StaWorker(RTLIL::Module *module) : design(module->design), module(module), sigmap(module), maxarrival(0)
{
TimingInfo timing;
for (auto cell : module->cells())
{
Module *inst_module = design->module(cell->type);
if (!inst_module) {
log_warning("Cell type '%s' not recognised! Ignoring.\n", log_id(cell->type));
continue;
}
if (!inst_module->get_blackbox_attribute()) {
log_warning("Cell type '%s' is not a black- nor white-box! Ignoring.\n", log_id(cell->type));
continue;
}
IdString derived_type = inst_module->derive(design, cell->parameters);
inst_module = design->module(derived_type);
log_assert(inst_module);
if (!timing.count(derived_type)) {
auto &t = timing.setup_module(inst_module);
if (t.has_inputs && t.comb.empty() && t.arrival.empty() && t.required.empty())
log_warning("Module '%s' has no timing arcs!\n", log_id(cell->type));
}
auto &t = timing.at(derived_type);
if (t.comb.empty() && t.arrival.empty() && t.required.empty())
continue;
pool<std::pair<SigBit,TimingInfo::NameBit>> src_bits, dst_bits;
for (auto &conn : cell->connections()) {
auto rhs = sigmap(conn.second);
for (auto i = 0; i < GetSize(rhs); i++) {
const auto &bit = rhs[i];
if (!bit.wire)
continue;
TimingInfo::NameBit namebit(conn.first,i);
if (cell->input(conn.first)) {
src_bits.insert(std::make_pair(bit,namebit));
auto it = t.required.find(namebit);
if (it == t.required.end())
continue;
auto r = endpoints.insert(bit);
if (r.second || r.first->second.required < it->second.first) {
r.first->second.sink = cell;
r.first->second.port = conn.first;
r.first->second.required = it->second.first;
}
}
if (cell->output(conn.first)) {
dst_bits.insert(std::make_pair(bit,namebit));
auto &d = data[bit];
d.driver = cell;
d.dst_port = conn.first;
driven.insert(bit);
auto it = t.arrival.find(namebit);
if (it == t.arrival.end())
continue;
const auto &s = it->second.second;
if (cell->hasPort(s.name)) {
auto s_bit = sigmap(cell->getPort(s.name)[s.offset]);
if (s_bit.wire)
data[s_bit].fanouts.emplace_back(bit,it->second.first,s.name);
}
}
}
}
for (const auto &s : src_bits)
for (const auto &d : dst_bits) {
auto it = t.comb.find(TimingInfo::BitBit(s.second,d.second));
if (it == t.comb.end())
continue;
data[s.first].fanouts.emplace_back(d.first,it->second,s.second.name);
}
}
for (auto port_name : module->ports) {
auto wire = module->wire(port_name);
if (wire->port_input) {
for (const auto &b : sigmap(wire)) {
queue.emplace_back(b);
driven.insert(b);
}
// All primary inputs to arrive at time zero
wire->set_intvec_attribute(ID::sta_arrival, std::vector<int>(GetSize(wire), 0));
}
if (wire->port_output)
for (const auto &b : sigmap(wire))
if (b.wire)
endpoints.insert(b);
}
}
void run()
{
while (!queue.empty()) {
auto b = queue.front();
queue.pop_front();
auto it = data.find(b);
if (it == data.end())
continue;
const auto& src_arrivals = b.wire->get_intvec_attribute(ID::sta_arrival);
log_assert(GetSize(src_arrivals) == GetSize(b.wire));
auto src_arrival = src_arrivals[b.offset];
for (const auto &d : it->second.fanouts) {
const auto &dst_bit = std::get<0>(d);
auto dst_arrivals = dst_bit.wire->get_intvec_attribute(ID::sta_arrival);
if (dst_arrivals.empty())
dst_arrivals = std::vector<int>(GetSize(dst_bit.wire), -1);
else
log_assert(GetSize(dst_arrivals) == GetSize(dst_bit.wire));
auto &dst_arrival = dst_arrivals[dst_bit.offset];
auto new_arrival = src_arrival + std::get<1>(d);
if (dst_arrival < new_arrival) {
auto dst_wire = dst_bit.wire;
dst_arrival = std::max(dst_arrival, new_arrival);
dst_wire->set_intvec_attribute(ID::sta_arrival, dst_arrivals);
queue.emplace_back(dst_bit);
data[dst_bit].backtrack = b;
data[dst_bit].src_port = std::get<2>(d);
auto it = endpoints.find(dst_bit);
if (it != endpoints.end())
new_arrival += it->second.required;
if (new_arrival > maxarrival && driven.count(b)) {
maxarrival = new_arrival;
maxbit = dst_bit;
}
}
}
}
auto b = maxbit;
if (b == SigBit()) {
log("No timing paths found.\n");
return;
}
log("Latest arrival time in '%s' is %d:\n", log_id(module), maxarrival);
auto it = endpoints.find(maxbit);
if (it != endpoints.end() && it->second.sink)
log(" %6d %s (%s.%s)\n", maxarrival, log_id(it->second.sink), log_id(it->second.sink->type), log_id(it->second.port));
else {
log(" %6d (%s)\n", maxarrival, b.wire->port_output ? "<primary output>" : "<unknown>");
if (!b.wire->port_output)
log_warning("Critical-path does not terminate in a recognised endpoint.\n");
}
auto jt = data.find(b);
while (jt != data.end()) {
int arrival = b.wire->get_intvec_attribute(ID::sta_arrival)[b.offset];
if (jt->second.driver) {
log(" %s\n", log_signal(b));
log(" %6d %s (%s.%s->%s)\n", arrival, log_id(jt->second.driver), log_id(jt->second.driver->type), log_id(jt->second.src_port), log_id(jt->second.dst_port));
}
else if (b.wire->port_input)
log(" %6d %s (%s)\n", arrival, log_signal(b), "<primary input>");
else
log_abort();
b = jt->second.backtrack;
jt = data.find(b);
}
std::map<int, unsigned> arrival_histogram;
for (const auto &i : endpoints) {
const auto &b = i.first;
if (!driven.count(b))
continue;
if (!b.wire->attributes.count(ID::sta_arrival)) {
log_warning("Endpoint %s.%s has no (* sta_arrival *) value.\n", log_id(module), log_signal(b));
continue;
}
auto arrival = b.wire->get_intvec_attribute(ID::sta_arrival)[b.offset];
if (arrival < 0) {
log_warning("Endpoint %s.%s has no (* sta_arrival *) value.\n", log_id(module), log_signal(b));
continue;
}
arrival += i.second.required;
arrival_histogram[arrival]++;
}
// Adapted from https://github.com/YosysHQ/nextpnr/blob/affb12cc27ebf409eade062c4c59bb98569d8147/common/timing.cc#L946-L969
if (arrival_histogram.size() > 0) {
unsigned num_bins = 20;
unsigned bar_width = 60;
auto min_arrival = arrival_histogram.begin()->first;
auto max_arrival = arrival_histogram.rbegin()->first;
auto bin_size = std::max<unsigned>(1, ceil((max_arrival - min_arrival + 1) / float(num_bins)));
std::vector<unsigned> bins(num_bins);
unsigned max_freq = 0;
for (const auto &i : arrival_histogram) {
auto &bin = bins[(i.first - min_arrival) / bin_size];
bin += i.second;
max_freq = std::max(max_freq, bin);
}
bar_width = std::min(bar_width, max_freq);
log("\n");
log("Arrival histogram:\n");
log(" legend: * represents %d endpoint(s)\n", max_freq / bar_width);
log(" + represents [1,%d) endpoint(s)\n", max_freq / bar_width);
for (int i = num_bins-1; i >= 0; --i)
log("(%6d, %6d] |%s%c\n", min_arrival + bin_size * (i + 1), min_arrival + bin_size * i,
std::string(bins[i] * bar_width / max_freq, '*').c_str(),
(bins[i] * bar_width) % max_freq > 0 ? '+' : ' ');
}
}
};
struct StaPass : public Pass {
StaPass() : Pass("sta", "perform static timing analysis") { }
void help() override
{
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
log("\n");
log(" sta [options] [selection]\n");
log("\n");
log("This command performs static timing analysis on the design. (Only considers\n");
log("paths within a single module, so the design must be flattened.)\n");
log("\n");
}
void execute(std::vector<std::string> args, RTLIL::Design *design) override
{
log_header(design, "Executing STA pass (static timing analysis).\n");
/*
size_t argidx;
for (argidx = 1; argidx < args.size(); argidx++) {
if (args[argidx] == "-TODO") {
continue;
}
break;
}
*/
extra_args(args, 1, design);
for (Module *module : design->selected_modules())
{
if (module->has_processes_warn())
continue;
StaWorker worker(module);
worker.run();
}
}
} StaPass;
PRIVATE_NAMESPACE_END