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router2: revisit nodes with lower cost
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@Ravenslofty
Ravenslofty committed Jun 13, 2023
1 parent 863ad4c commit 8935c18
Showing 1 changed file with 28 additions and 23 deletions.
51 changes: 28 additions & 23 deletions common/route/router2.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -94,6 +94,7 @@ struct Router2
// Visit data
PipId pip_fwd, pip_bwd;
bool visited_fwd = false, visited_bwd = false;
float cost_fwd = 0.0, cost_bwd = 0.0;
};

Context *ctx;
Expand Down Expand Up @@ -522,6 +523,8 @@ struct Router2
flat_wires[w].pip_bwd = PipId();
flat_wires[w].visited_fwd = false;
flat_wires[w].visited_bwd = false;
flat_wires[w].cost_fwd = 0.0;
flat_wires[w].cost_bwd = 0.0;
}
t.dirty_wires.clear();
}
Expand Down Expand Up @@ -559,25 +562,27 @@ struct Router2
}

// Functions for marking wires as visited, and checking if they have already been visited
void set_visited_fwd(ThreadContext &t, int wire, PipId pip)
void set_visited_fwd(ThreadContext &t, int wire, PipId pip, float cost)
{
auto &wd = flat_wires.at(wire);
if (!wd.visited_fwd && !wd.visited_bwd)
t.dirty_wires.push_back(wire);
wd.pip_fwd = pip;
wd.visited_fwd = true;
wd.cost_fwd = cost;
}
void set_visited_bwd(ThreadContext &t, int wire, PipId pip)
void set_visited_bwd(ThreadContext &t, int wire, PipId pip, float cost)
{
auto &wd = flat_wires.at(wire);
if (!wd.visited_fwd && !wd.visited_bwd)
t.dirty_wires.push_back(wire);
wd.pip_bwd = pip;
wd.visited_bwd = true;
wd.cost_bwd = cost;
}

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_fwd(int wire, float cost) { return flat_wires.at(wire).visited_fwd && flat_wires.at(wire).cost_fwd <= cost; }
bool was_visited_bwd(int wire, float cost) { return flat_wires.at(wire).visited_bwd && flat_wires.at(wire).cost_bwd <= cost; }

float get_arc_crit(NetInfo *net, store_index<PortRef> i)
{
Expand Down Expand Up @@ -652,7 +657,7 @@ struct Router2
int wire_idx = wire_to_idx.at(wire);
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));
set_visited_fwd(t, wire_idx, PipId());
set_visited_fwd(t, wire_idx, PipId(), 0.0);
};
auto &dst_data = flat_wires.at(dst_wire_idx);
// Look for nearby existing routing
Expand All @@ -674,15 +679,15 @@ struct Router2
// Seed forwards with the source wire, if less than 8 existing wires added
seed_queue_fwd(src_wire);
} else {
set_visited_fwd(t, src_wire_idx, PipId());
set_visited_fwd(t, src_wire_idx, PipId(), 0.0);
}
auto seed_queue_bwd = [&](WireId wire) {
WireScore base_score;
base_score.cost = 0;
int wire_idx = wire_to_idx.at(wire);
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));
set_visited_bwd(t, wire_idx, PipId());
set_visited_bwd(t, wire_idx, PipId(), 0.0);
};

// Seed backwards with the dest wire
Expand All @@ -701,7 +706,7 @@ struct Router2
auto curr = t.fwd_queue.top();
t.fwd_queue.pop();
++explored;
if (was_visited_bwd(curr.wire)) {
if (was_visited_bwd(curr.wire, FLT_MAX)) {
// Meet in the middle; done
midpoint_wire = curr.wire;
break;
Expand All @@ -715,7 +720,11 @@ struct Router2
continue;
WireId next = ctx->getPipDstWire(dh);
int next_idx = wire_to_idx.at(next);
if (was_visited_fwd(next_idx)) {
WireScore next_score;
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, crit_weight);
if (was_visited_fwd(next_idx, next_score.cost)) {
// Don't expand the same node twice.
continue;
}
Expand All @@ -731,11 +740,7 @@ struct Router2
continue;
if (!thread_test_wire(t, nwd))
continue; // thread safety issue
WireScore next_score;
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, crit_weight);
set_visited_fwd(t, next_idx, dh);
set_visited_fwd(t, next_idx, dh, next_score.cost);
t.fwd_queue.push(QueuedWire(next_idx, next_score, t.rng.rng()));
}
}
Expand All @@ -744,7 +749,7 @@ struct Router2
auto curr = t.bwd_queue.top();
t.bwd_queue.pop();
++explored;
if (was_visited_fwd(curr.wire)) {
if (was_visited_fwd(curr.wire, FLT_MAX)) {

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@whitequark

whitequark Jun 14, 2023

Member

This broke the YoWASP build: https://github.com/YoWASP/nextpnr/actions/runs/5262021196/jobs/9510783381

I think you need to #include <cfloat> above.
// Meet in the middle; done
midpoint_wire = curr.wire;
break;
Expand All @@ -765,7 +770,11 @@ struct Router2
continue;
WireId next = ctx->getPipSrcWire(uh);
int next_idx = wire_to_idx.at(next);
if (was_visited_bwd(next_idx)) {
WireScore next_score;
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, crit_weight);
if (was_visited_bwd(next_idx, next_score.cost)) {
// Don't expand the same node twice.
continue;
}
Expand All @@ -777,11 +786,7 @@ struct Router2
continue;
if (!thread_test_wire(t, nwd))
continue; // thread safety issue
WireScore next_score;
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, crit_weight);
set_visited_bwd(t, next_idx, uh);
set_visited_bwd(t, next_idx, uh, next_score.cost);
t.bwd_queue.push(QueuedWire(next_idx, next_score, t.rng.rng()));
}
}
Expand All @@ -793,7 +798,7 @@ struct Router2
if (midpoint_wire != -1) {
ROUTE_LOG_DBG(" Routed (explored %d wires): ", explored);
int cursor_bwd = midpoint_wire;
while (was_visited_fwd(cursor_bwd)) {
while (was_visited_fwd(cursor_bwd, FLT_MAX)) {
PipId pip = flat_wires.at(cursor_bwd).pip_fwd;
if (pip == PipId() && cursor_bwd != src_wire_idx)
break;
Expand Down Expand Up @@ -832,7 +837,7 @@ struct Router2
NPNR_ASSERT(cursor_bwd == src_wire_idx);

int cursor_fwd = midpoint_wire;
while (was_visited_bwd(cursor_fwd)) {
while (was_visited_bwd(cursor_fwd, FLT_MAX)) {
PipId pip = flat_wires.at(cursor_fwd).pip_bwd;
if (pip == PipId()) {
break;
Expand Down

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