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router2: Adding some criticality heuristics

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Signed-off-by: gatecat <gatecat@ds0.me>
This commit is contained in:
gatecat 2021-08-15 09:34:27 +01:00
parent 64f6b8bc67
commit 2a856db72c
1 changed files with 29 additions and 13 deletions
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42
common/router2.cc
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@ -53,7 +53,6 @@ struct Router2
WireId sink_wire; WireId sink_wire;
ArcBounds bb; ArcBounds bb;
bool routed = false; bool routed = false;
float arc_crit = 0;
}; };
// As we allow overlap at first; the nextpnr bind functions can't be used // As we allow overlap at first; the nextpnr bind functions can't be used
@ -352,7 +351,7 @@ struct Router2
ad.routed = false; ad.routed = false;
} }
float score_wire_for_arc(NetInfo *net, size_t user, size_t phys_pin, WireId wire, PipId pip) float score_wire_for_arc(NetInfo *net, size_t user, size_t phys_pin, WireId wire, PipId pip, float crit_weight)
{ {
auto &wd = wire_data(wire); auto &wd = wire_data(wire);
auto &nd = nets.at(net->udata); auto &nd = nets.at(net->udata);
@ -366,16 +365,16 @@ struct Router2
overuse -= 1; overuse -= 1;
source_uses = nd.wires.at(wire).second; source_uses = nd.wires.at(wire).second;
} }
float present_cost = 1.0f + overuse * curr_cong_weight; float present_cost = 1.0f + overuse * curr_cong_weight * crit_weight;
if (pip != PipId()) { if (pip != PipId()) {
Loc pl = ctx->getPipLocation(pip); Loc pl = ctx->getPipLocation(pip);
bias_cost = cfg.bias_cost_factor * (base_cost / int(net->users.size())) * bias_cost = cfg.bias_cost_factor * (base_cost / int(net->users.size())) *
((std::abs(pl.x - nd.cx) + std::abs(pl.y - nd.cy)) / float(nd.hpwl)); ((std::abs(pl.x - nd.cx) + std::abs(pl.y - nd.cy)) / float(nd.hpwl));
} }
return base_cost * hist_cost * present_cost / (1 + source_uses) + bias_cost; return base_cost * hist_cost * present_cost / (1 + (source_uses * crit_weight)) + bias_cost;
} }
float get_togo_cost(NetInfo *net, size_t user, int wire, WireId src_sink, bool bwd = false) float get_togo_cost(NetInfo *net, size_t user, int wire, WireId src_sink, float crit_weight, bool bwd = false)
{ {
auto &nd = nets.at(net->udata); auto &nd = nets.at(net->udata);
auto &wd = flat_wires[wire]; auto &wd = flat_wires[wire];
@ -385,7 +384,7 @@ struct Router2
} }
// FIXME: timing/wirelength balance? // FIXME: timing/wirelength balance?
delay_t est_delay = ctx->estimateDelay(bwd ? src_sink : wd.w, bwd ? wd.w : src_sink); delay_t est_delay = ctx->estimateDelay(bwd ? src_sink : wd.w, bwd ? wd.w : src_sink);
return (ctx->getDelayNS(est_delay) / (1 + source_uses)) + cfg.ipin_cost_adder; return (ctx->getDelayNS(est_delay) / (1 + source_uses * crit_weight)) + cfg.ipin_cost_adder;
} }
bool check_arc_routing(NetInfo *net, size_t usr, size_t phys_pin) bool check_arc_routing(NetInfo *net, size_t usr, size_t phys_pin)
@ -568,6 +567,13 @@ struct Router2
bool was_visited_fwd(int wire) { return flat_wires.at(wire).visited_fwd; } bool was_visited_fwd(int wire) { return flat_wires.at(wire).visited_fwd; }
bool was_visited_bwd(int wire) { return flat_wires.at(wire).visited_bwd; } bool was_visited_bwd(int wire) { return flat_wires.at(wire).visited_bwd; }
float get_arc_crit(NetInfo *net, size_t i)
{
if (!timing_driven)
return 0;
return tmg.get_criticality(CellPortKey(net->users.at(i)));
}
ArcRouteResult route_arc(ThreadContext &t, NetInfo *net, size_t i, size_t phys_pin, bool is_mt, bool is_bb = true) 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 // Do some initial lookups and checks
@ -586,6 +592,9 @@ struct Router2
ctx->nameOf(usr.cell)); ctx->nameOf(usr.cell));
int src_wire_idx = wire_to_idx.at(src_wire); int src_wire_idx = wire_to_idx.at(src_wire);
int dst_wire_idx = wire_to_idx.at(dst_wire); int dst_wire_idx = wire_to_idx.at(dst_wire);
// Calculate a timing weight based on criticality
float crit = get_arc_crit(net, i);
float crit_weight = (1.0f - std::pow(crit, 2));
// Check if arc was already done _in this iteration_ // Check if arc was already done _in this iteration_
if (t.processed_sinks.count(dst_wire)) if (t.processed_sinks.count(dst_wire))
return ARC_SUCCESS; return ARC_SUCCESS;
@ -621,7 +630,7 @@ struct Router2
WireScore base_score; WireScore base_score;
base_score.cost = wire_cost; base_score.cost = wire_cost;
int wire_idx = wire_to_idx.at(wire); int wire_idx = wire_to_idx.at(wire);
base_score.togo_cost = get_togo_cost(net, i, wire_idx, dst_wire, false); base_score.togo_cost = get_togo_cost(net, i, wire_idx, dst_wire, false, crit_weight);
t.fwd_queue.push(QueuedWire(wire_idx, base_score)); t.fwd_queue.push(QueuedWire(wire_idx, base_score));
set_visited_fwd(t, wire_idx, PipId()); set_visited_fwd(t, wire_idx, PipId());
}; };
@ -651,7 +660,7 @@ struct Router2
WireScore base_score; WireScore base_score;
base_score.cost = 0; base_score.cost = 0;
int wire_idx = wire_to_idx.at(wire); int wire_idx = wire_to_idx.at(wire);
base_score.togo_cost = get_togo_cost(net, i, wire_idx, src_wire, true); base_score.togo_cost = get_togo_cost(net, i, wire_idx, src_wire, true, crit_weight);
t.bwd_queue.push(QueuedWire(wire_idx, base_score)); t.bwd_queue.push(QueuedWire(wire_idx, base_score));
set_visited_bwd(t, wire_idx, PipId()); set_visited_bwd(t, wire_idx, PipId());
}; };
@ -702,8 +711,9 @@ struct Router2
if (!thread_test_wire(t, nwd)) if (!thread_test_wire(t, nwd))
continue; // thread safety issue continue; // thread safety issue
WireScore next_score; WireScore next_score;
next_score.cost = curr.score.cost + score_wire_for_arc(net, i, phys_pin, next, dh); next_score.cost = curr.score.cost + score_wire_for_arc(net, i, phys_pin, next, dh, crit_weight);
next_score.togo_cost = cfg.estimate_weight * get_togo_cost(net, i, next_idx, dst_wire, false); next_score.togo_cost =
cfg.estimate_weight * get_togo_cost(net, i, next_idx, dst_wire, false, crit_weight);
set_visited_fwd(t, next_idx, dh); set_visited_fwd(t, next_idx, dh);
t.fwd_queue.push(QueuedWire(next_idx, next_score, t.rng.rng())); t.fwd_queue.push(QueuedWire(next_idx, next_score, t.rng.rng()));
} }
@ -746,8 +756,9 @@ struct Router2
if (!thread_test_wire(t, nwd)) if (!thread_test_wire(t, nwd))
continue; // thread safety issue continue; // thread safety issue
WireScore next_score; WireScore next_score;
next_score.cost = curr.score.cost + score_wire_for_arc(net, i, phys_pin, next, uh); next_score.cost = curr.score.cost + score_wire_for_arc(net, i, phys_pin, next, uh, crit_weight);
next_score.togo_cost = cfg.estimate_weight * get_togo_cost(net, i, next_idx, src_wire, true); next_score.togo_cost =
cfg.estimate_weight * get_togo_cost(net, i, next_idx, src_wire, true, crit_weight);
set_visited_bwd(t, next_idx, uh); set_visited_bwd(t, next_idx, uh);
t.bwd_queue.push(QueuedWire(next_idx, next_score, t.rng.rng())); t.bwd_queue.push(QueuedWire(next_idx, next_score, t.rng.rng()));
} }
@ -870,6 +881,11 @@ struct Router2
t.route_arcs.emplace_back(i, j); t.route_arcs.emplace_back(i, j);
} }
} }
// Route most critical arc first
std::stable_sort(t.route_arcs.begin(), t.route_arcs.end(),
[&](std::pair<size_t, size_t> a, std::pair<size_t, size_t> b) {
return get_arc_crit(net, a.first) > get_arc_crit(net, b.first);
});
for (auto a : t.route_arcs) { for (auto a : t.route_arcs) {
auto res1 = route_arc(t, net, a.first, a.second, is_mt, true); auto res1 = route_arc(t, net, a.first, a.second, is_mt, true);
if (res1 == ARC_FATAL) if (res1 == ARC_FATAL)
@ -1345,7 +1361,7 @@ struct Router2
do { do {
ctx->sorted_shuffle(route_queue); ctx->sorted_shuffle(route_queue);
if (timing_driven && (int(route_queue.size()) > (int(nets_by_udata.size()) / 50))) { 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 // Heuristic: reduce runtime by skipping STA in the case of a "long tail" of a few
// congested nodes // congested nodes
tmg.run(iter == 1); tmg.run(iter == 1);