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router2: Experiment with data structures

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Signed-off-by: David Shah <dave@ds0.me>
This commit is contained in:
David Shah 2020-01-14 15:00:15 +00:00
parent 7ac43e5f00
commit 2de98386a7
1 changed files with 63 additions and 36 deletions
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99
common/router2.cc
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@ -64,16 +64,31 @@ struct Router2
int total_route_us = 0;
};
struct WireScore
{
float cost;
float togo_cost;
delay_t delay;
float total() const { return cost + togo_cost; }
};
struct PerWireData
{
// net --> number of arcs; driving pip
std::unordered_map<int, std::pair<int, PipId>> bound_nets;
boost::container::flat_map<int, std::pair<int, PipId>> bound_nets;
// Historical congestion cost
float hist_cong_cost = 1.0;
// Wire is unavailable as locked to another arc
bool unavailable = false;
// This wire has to be used for this net
int reserved_net = -1;
// Visit data
struct
{
bool dirty = false, visited = false;
PipId pip;
WireScore score;
} visit;
};
float present_wire_cost(const PerWireData &w, int net_uid)
@ -87,14 +102,6 @@ struct Router2
return 1 + other_sources * curr_cong_weight;
}
struct WireScore
{
float cost;
float togo_cost;
delay_t delay;
float total() const { return cost + togo_cost; }
};
Context *ctx;
// Use 'udata' for fast net lookups and indexing
@ -211,13 +218,7 @@ struct Router2
}
double curr_cong_weight, hist_cong_weight, estimate_weight;
// Soft-route a net (don't touch Arch data structures which might not be thread safe)
// If is_mt is true, then strict bounding box rules are applied and log_* won't be called
struct VisitInfo
{
WireScore score;
PipId pip;
};
struct ThreadContext
{
// Nets to route
@ -228,13 +229,13 @@ struct Router2
std::vector<int> route_arcs;
std::priority_queue<QueuedWire, std::vector<QueuedWire>, QueuedWire::Greater> queue;
std::unordered_map<WireId, VisitInfo> visited;
// Special case where one net has multiple logical arcs to the same physical sink
std::unordered_set<WireId> processed_sinks;
// Backwards routing
std::queue<WireId> backwards_queue;
std::unordered_map<WireId, PipId> backwards_pip;
std::vector<WireId> dirty_wires;
};
enum ArcRouteResult
@ -401,6 +402,29 @@ struct Router2
}
}
void reset_wires(ThreadContext &t)
{
for (auto w : t.dirty_wires) {
wires.at(w).visit.visited = false;
wires.at(w).visit.dirty = false;
wires.at(w).visit.pip = PipId();
wires.at(w).visit.score = WireScore();
}
t.dirty_wires.clear();
}
void set_visited(ThreadContext &t, WireId wire, PipId pip, WireScore score)
{
auto &v = wires.at(wire).visit;
if (!v.dirty)
t.dirty_wires.push_back(wire);
v.dirty = true;
v.visited = true;
v.pip = pip;
v.score = score;
}
bool was_visited(WireId wire) { return wires.at(wire).visit.visited; }
ArcRouteResult route_arc(ThreadContext &t, NetInfo *net, size_t i, bool is_mt, bool is_bb = true)
{
@ -436,7 +460,6 @@ struct Router2
// bidirectional approach
int backwards_iter = 0;
int backwards_limit = ctx->getBelGlobalBuf(net->driver.cell->bel) ? 20000 : 15;
t.backwards_pip.clear();
t.backwards_queue.push(dst_wire);
while (!t.backwards_queue.empty() && backwards_iter < backwards_limit) {
WireId cursor = t.backwards_queue.front();
@ -466,7 +489,7 @@ struct Router2
if (p == PipId())
break;
cursor2 = ctx->getPipSrcWire(p);
t.backwards_pip[cursor2] = p;
set_visited(t, cursor2, p, WireScore());
}
break;
}
@ -480,7 +503,7 @@ struct Router2
if (cpip != PipId() && cpip != uh)
continue; // don't allow multiple pips driving a wire with a net
WireId next = ctx->getPipSrcWire(uh);
if (t.backwards_pip.count(next))
if (was_visited(next))
continue; // skip wires that have already been visited
auto &wd = wires.at(next);
if (wd.unavailable)
@ -490,20 +513,20 @@ struct Router2
if (wd.bound_nets.size() > 1 || (wd.bound_nets.size() == 1 && !wd.bound_nets.count(net->udata)))
continue; // never allow congestion in backwards routing
t.backwards_queue.push(next);
t.backwards_pip[next] = uh;
set_visited(t, next, uh, WireScore());
}
if (did_something)
++backwards_iter;
}
// Check if backwards routing succeeded in reaching source
if (t.backwards_pip.count(src_wire)) {
if (was_visited(src_wire)) {
ROUTE_LOG_DBG(" Routed (backwards): ");
WireId cursor_fwd = src_wire;
bind_pip_internal(net, i, src_wire, PipId());
while (t.backwards_pip.count(cursor_fwd)) {
auto &v = t.backwards_pip.at(cursor_fwd);
cursor_fwd = ctx->getPipDstWire(v);
bind_pip_internal(net, i, cursor_fwd, v);
while (was_visited(cursor_fwd)) {
auto &v = wires.at(cursor_fwd).visit;
cursor_fwd = ctx->getPipDstWire(v.pip);
bind_pip_internal(net, i, cursor_fwd, v.pip);
if (ctx->debug) {
auto &wd = wires.at(cursor_fwd);
ROUTE_LOG_DBG(" wire: %s (curr %d hist %f)\n", ctx->nameOfWire(cursor_fwd),
@ -513,11 +536,12 @@ struct Router2
NPNR_ASSERT(cursor_fwd == dst_wire);
ad.routed = true;
t.processed_sinks.insert(dst_wire);
reset_wires(t);
return ARC_SUCCESS;
}
// Normal forwards A* routing
t.visited.clear();
reset_wires(t);
WireScore base_score;
base_score.cost = 0;
base_score.delay = ctx->getWireDelay(src_wire).maxDelay();
@ -525,8 +549,7 @@ struct Router2
// Add source wire to queue
t.queue.push(QueuedWire(src_wire, PipId(), Loc(), base_score));
t.visited[src_wire].score = base_score;
t.visited[src_wire].pip = PipId();
set_visited(t, src_wire, PipId(), base_score);
int toexplore = 25000 * std::max(1, (ad.bb.x1 - ad.bb.x0) + (ad.bb.y1 - ad.bb.y0));
int iter = 0;
@ -559,6 +582,8 @@ struct Router2
#endif
// Evaluate score of next wire
WireId next = ctx->getPipDstWire(dh);
if (was_visited(next))
continue;
#if 1
if (debug_arc)
ROUTE_LOG_DBG(" src wire %s\n", ctx->nameOfWire(next));
@ -575,7 +600,8 @@ struct Router2
next_score.delay =
curr.score.delay + ctx->getPipDelay(dh).maxDelay() + ctx->getWireDelay(next).maxDelay();
next_score.togo_cost = 1.75 * get_togo_cost(net, i, next, dst_wire);
if (!t.visited.count(next) || (t.visited.at(next).score.total() > next_score.total())) {
const auto &v = wires.at(next).visit;
if (!v.visited || (v.score.total() > next_score.total())) {
++explored;
#if 0
ROUTE_LOG_DBG("exploring wire %s cost %f togo %f\n", ctx->nameOfWire(next), next_score.cost,
@ -583,19 +609,18 @@ struct Router2
#endif
// Add wire to queue if it meets criteria
t.queue.push(QueuedWire(next, dh, ctx->getPipLocation(dh), next_score, ctx->rng()));
t.visited[next].score = next_score;
t.visited[next].pip = dh;
set_visited(t, next, dh, next_score);
if (next == dst_wire) {
toexplore = std::min(toexplore, iter + 5);
}
}
}
}
if (t.visited.count(dst_wire)) {
if (was_visited(dst_wire)) {
ROUTE_LOG_DBG(" Routed (explored %d wires): ", explored);
WireId cursor_bwd = dst_wire;
while (t.visited.count(cursor_bwd)) {
auto &v = t.visited.at(cursor_bwd);
while (was_visited(cursor_bwd)) {
auto &v = wires.at(cursor_bwd).visit;
bind_pip_internal(net, i, cursor_bwd, v.pip);
if (ctx->debug) {
auto &wd = wires.at(cursor_bwd);
@ -613,8 +638,10 @@ struct Router2
}
t.processed_sinks.insert(dst_wire);
ad.routed = true;
reset_wires(t);
return ARC_SUCCESS;
} else {
reset_wires(t);
return ARC_RETRY_WITHOUT_BB;
}
}