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improve lb_route to avoid routing combinational loops

This commit is contained in:
tangxifan 2020-03-12 23:58:56 -06:00
parent 773e6da308
commit 81e5af464e
1 changed files with 24 additions and 1 deletions
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25
openfpga/src/repack/lb_router.cpp
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@ -216,12 +216,24 @@ bool LbRouter::try_route_net(const LbRRGraph& lb_rr_graph,
std::unordered_map<const t_pb_graph_node*, const t_mode*>& mode_map,
const bool& verbosity) {
/* Quick check: if all the net can be skipped, we return route succeed */
bool skip_route = true;
for (size_t isrc = 0; isrc < lb_net_sources_[net_idx].size(); ++isrc) {
if (false == is_skip_route_net(lb_rr_graph, lb_net_rt_trees_[net_idx][isrc])) {
skip_route = false;
break;
}
}
if (true == skip_route) {
return true;
}
std::vector<bool> sink_routed(lb_net_sinks_[net_idx].size(), false);
for (size_t isrc = 0; isrc < lb_net_sources_[net_idx].size(); ++isrc) {
if (true == is_skip_route_net(lb_rr_graph, lb_net_rt_trees_[net_idx][isrc])) {
return true;
continue;
}
commit_remove_rt(lb_rr_graph, lb_net_rt_trees_[net_idx][isrc], RT_REMOVE, mode_map);
@ -232,6 +244,17 @@ bool LbRouter::try_route_net(const LbRRGraph& lb_rr_graph,
/* Route each sink of net */
for (size_t isink = 0; isink < lb_net_sinks_[net_idx].size(); ++isink) {
/* Do not route the sink if it share the same pb_type as source
* This is actually forbidden! This will definitely create a combinational loop
*/
if ( (nullptr != lb_rr_graph.node_pb_graph_pin(lb_net_sinks_[net_idx][isink]))
&& (nullptr != lb_rr_graph.node_pb_graph_pin(lb_net_sources_[net_idx][isrc])) ) {
if (lb_rr_graph.node_pb_graph_pin(lb_net_sinks_[net_idx][isink])->parent_node
== lb_rr_graph.node_pb_graph_pin(lb_net_sources_[net_idx][isrc])->parent_node) {
continue;
}
}
/* Skip routed nets */
if (true == sink_routed[isink]) {
continue;