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router2: first pass at reserved wires

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Signed-off-by: David Shah <dave@ds0.me>
This commit is contained in:
David Shah 2019-12-03 13:44:16 +00:00
parent 50b120528a
commit 3d739b5916
1 changed files with 65 additions and 3 deletions
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68
common/router2.cc
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@ -62,12 +62,12 @@ struct Router2
{
// net --> number of arcs; driving pip
std::unordered_map<int, std::pair<int, PipId>> bound_nets;
// Which net is bound in the Arch API
int arch_bound_net = -1;
// 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;
};
float present_wire_cost(const PerWireData &w, int net_uid)
@ -165,7 +165,6 @@ struct Router2
NetInfo *bound = ctx->getBoundWireNet(wire);
if (bound != nullptr) {
wires[wire].bound_nets[bound->udata] = std::make_pair(1, bound->wires.at(wire).pip);
wires[wire].arch_bound_net = bound->udata;
if (bound->wires.at(wire).strength > STRENGTH_STRONG)
wires[wire].unavailable = true;
}
@ -332,6 +331,64 @@ struct Router2
return (cursor == src_wire);
}
// Returns true if a wire contains no source ports or driving pips
bool is_wire_undriveable(WireId wire)
{
for (auto bp : ctx->getWireBelPins(wire))
if (ctx->getBelPinType(bp.bel, bp.pin) != PORT_IN)
return false;
for (auto p : ctx->getPipsUphill(wire))
return false;
return true;
}
// Find all the wires that must be used to route a given arc
void reserve_wires_for_arc(NetInfo *net, size_t i)
{
// This is slightly tricky, because of the possibility of "diamonds"
// eg /--C--\\
// sink ----B----D--...
// we need to discover that D is a reserved wire; despite the branch and choice of B/C
WireId src = ctx->getNetinfoSourceWire(net);
WireId sink = ctx->getNetinfoSinkWire(net, net->users.at(i));
if (sink == WireId())
return;
std::unordered_set<WireId> rsv;
WireId cursor = sink;
bool done = false;
while (!done) {
auto &wd = wires.at(cursor);
wd.reserved_net = net->udata;
if (cursor == src)
break;
WireId next_cursor;
for (auto uh : ctx->getPipsUphill(cursor)) {
WireId w = ctx->getPipSrcWire(uh);
if (is_wire_undriveable(w))
continue;
if (next_cursor != WireId()) {
done = true;
break;
}
next_cursor = w;
}
if (next_cursor == WireId())
break;
cursor = next_cursor;
}
}
void find_all_reserved_wires()
{
for (auto net : nets_by_udata) {
WireId src = ctx->getNetinfoSourceWire(net);
if (src == WireId())
continue;
for (size_t i = 0; i < net->users.size(); i++)
reserve_wires_for_arc(net, i);
}
}
ArcRouteResult route_arc(ThreadContext &t, NetInfo *net, size_t i, bool is_mt, bool is_bb = true)
{
@ -416,6 +473,8 @@ struct Router2
auto &wd = wires.at(next);
if (wd.unavailable)
continue;
if (wd.reserved_net != -1 && wd.reserved_net != net->udata)
continue;
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);
@ -490,6 +549,8 @@ struct Router2
auto &nwd = wires.at(next);
if (nwd.unavailable)
continue;
if (nwd.reserved_net != -1 && nwd.reserved_net != net->udata)
continue;
if (nwd.bound_nets.count(net->udata) && nwd.bound_nets.at(net->udata).second != dh)
continue;
WireScore next_score;
@ -859,6 +920,7 @@ struct Router2
{
setup_nets();
setup_wires();
find_all_reserved_wires();
partition_nets();
curr_cong_weight = 0.5;
hist_cong_weight = 1.0;