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router2: Improve backwards routing of some cases

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Signed-off-by: David Shah <dave@ds0.me>
This commit is contained in:
David Shah 2019-11-20 15:13:28 +00:00
parent 363d664f27
commit 59c554b50a
1 changed files with 27 additions and 1 deletions
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28
common/router2.cc
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@ -374,8 +374,34 @@ struct Router2
t.backwards_queue.pop();
auto &cwd = wires.at(cursor);
PipId cpip;
if (cwd.bound_nets.count(net->udata))
if (cwd.bound_nets.count(net->udata)) {
// If we can tack onto existing routing; try that
// Only do this if the existing routing is uncontented; however
WireId cursor2 = cursor;
bool bwd_merge_fail = false;
while (wires.at(cursor2).bound_nets.count(net->udata)) {
if (wires.at(cursor2).bound_nets.size() > 1) {
bwd_merge_fail = true;
break;
}
PipId p = wires.at(cursor2).bound_nets.at(net->udata).second;
if (p == PipId())
break;
cursor2 = ctx->getPipSrcWire(p);
}
if (!bwd_merge_fail && cursor2 == src_wire) {
// Found a path to merge to existing routing; backwards
cursor2 = cursor;
while (wires.at(cursor2).bound_nets.count(net->udata)) {
PipId p = wires.at(cursor2).bound_nets.at(net->udata).second;
if (p == PipId())
break;
cursor2 = ctx->getPipSrcWire(p);
t.backwards_pip[cursor2] = p;
}
}
cpip = cwd.bound_nets.at(net->udata).second;
}
bool did_something = false;
for (auto uh : ctx->getPipsUphill(cursor)) {
did_something = true;