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Spot a bug in lb router where path finder fail to use low-occupancy node when expanding the tree

This commit is contained in:
tangxifan 2020-03-12 22:53:17 -06:00
parent f90dc5c296
commit 773e6da308
4 changed files with 81 additions and 16 deletions
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67
openfpga/src/repack/lb_router.cpp
View File

@ -94,6 +94,11 @@ bool LbRouter::is_route_success(const LbRRGraph& lb_rr_graph) const {
for (const LbRRNodeId& inode : lb_rr_graph.nodes()) {
if (routing_status_[inode].occ > lb_rr_graph.node_capacity(inode)) {
VTR_LOGV(lb_rr_graph.node_pb_graph_pin(inode),
"Route failed due to overuse pin '%s': occupancy '%ld' > capacity '%ld'!\n",
lb_rr_graph.node_pb_graph_pin(inode)->to_string().c_str(),
routing_status_[inode].occ,
lb_rr_graph.node_capacity(inode));
return false;
}
}
@ -243,18 +248,22 @@ bool LbRouter::try_route_net(const LbRRGraph& lb_rr_graph,
*/
sink_routed[isink] = !try_expand_nodes(atom_nlist, lb_rr_graph, net_idx, exp_node, isrc, isink, mode_status_.expand_all_modes, verbosity);
/* TODO: Debug codes, to be removed
if (true == sink_routed[isink]) {
VTR_LOGV(verbosity,
"Succeed to expand routing tree from source pin '%s' to sink pin '%s'!\n",
lb_rr_graph.node_pb_graph_pin(lb_net_sources_[net_idx][isrc])->to_string().c_str(),
lb_rr_graph.node_pb_graph_pin(lb_net_sinks_[net_idx][isink])->to_string().c_str());
}
*/
/* IMPORTANT: We do not need expand all the modes for physical repack
if (false == sink_routed[isink] && false == mode_status_.expand_all_modes) {
mode_status_.try_expand_all_modes = true;
mode_status_.expand_all_modes = true;
continue;
}
*/
if (exp_node.node_index == lb_net_sinks_[net_idx][isink]) {
/* Net terminal is routed, add this to the route tree, clear data structures, and keep going */
@ -274,13 +283,17 @@ bool LbRouter::try_route_net(const LbRRGraph& lb_rr_graph,
}
}
/*
if (true == sink_routed[isink]) {
VTR_LOGV(verbosity,
"Routing succeeded from source pin '%s' to sink pin '%s'!\n",
lb_rr_graph.node_pb_graph_pin(lb_net_sources_[net_idx][isrc])->to_string().c_str(),
lb_rr_graph.node_pb_graph_pin(lb_net_sinks_[net_idx][isink])->to_string().c_str());
}
*/
/* Increment explored node indices only when routing is successful */
if (true == sink_routed[isink]) {
explore_id_index_++;
if (explore_id_index_ > 2000000000) {
/* overflow protection */
@ -290,21 +303,44 @@ bool LbRouter::try_route_net(const LbRRGraph& lb_rr_graph,
explore_id_index_ = 1;
}
}
} else {
/* Route failed, reset the explore id index */
reset_explored_node_tb();
for (const LbRRNodeId& id : lb_rr_graph.nodes()) {
explored_node_tb_[id].explored_id = OPEN;
explored_node_tb_[id].enqueue_id = OPEN;
explore_id_index_ = 1;
}
}
}
/* If routing succeed so far, we will try to save(commit) results
/* If any sinks are managed to be routed, we will try to save(commit) results
* to route tree.
* During this process, we will check if there is any
* nodes using different modes under the same pb_type
* If so, we have conflicts and routing is considered to be failure
*/
bool any_sink_routed = false;
for (size_t isink = 0; isink < sink_routed.size(); ++isink) {
if (true == sink_routed[isink]) {
any_sink_routed = true;
break;
}
}
if (true == any_sink_routed) {
commit_remove_rt(lb_rr_graph, lb_net_rt_trees_[net_idx][isrc], RT_COMMIT, mode_map);
if (true == mode_status_.is_mode_conflict) {
VTR_LOGV(verbosity,
"Route fail due to mode conflicts when commiting the routing tree!\n");
for (size_t isink = 0; isink < sink_routed.size(); ++isink) {
/* Change routed sinks to failure */
if (true == sink_routed[isink]) {
sink_routed[isink] = false;
}
}
}
}
}
/* Check the routing status for all the sinks */
bool route_succeed = true;
@ -526,6 +562,11 @@ void LbRouter::commit_remove_rt(const LbRRGraph& lb_rr_graph,
explored_node_tb_[inode].inet = NetId::INVALID();
}
if (op == RT_COMMIT) {
VTR_LOGV(lb_rr_graph.node_pb_graph_pin(inode),
"Commit node '%s' to routing tree\n",
lb_rr_graph.node_pb_graph_pin(inode)->to_string().c_str());
}
routing_status_[inode].occ += incr;
VTR_ASSERT(routing_status_[inode].occ >= 0);
@ -702,11 +743,23 @@ void LbRouter::expand_edges(const LbRRGraph& lb_rr_graph,
if (explored_node_tb_[enode.node_index].enqueue_id == explore_id_index_) {
if (enode.cost < explored_node_tb_[enode.node_index].enqueue_cost) {
pq_.push(enode);
/*
if (nullptr != lb_rr_graph.node_pb_graph_pin(enode.node_index)) {
VTR_LOG("Added node '%s' to priority queue\n",
lb_rr_graph.node_pb_graph_pin(enode.node_index)->to_string().c_str());
}
*/
}
} else {
explored_node_tb_[enode.node_index].enqueue_id = explore_id_index_;
explored_node_tb_[enode.node_index].enqueue_cost = enode.cost;
pq_.push(enode);
/*
if (nullptr != lb_rr_graph.node_pb_graph_pin(enode.node_index)) {
VTR_LOG("Added node '%s' to priority queue\n",
lb_rr_graph.node_pb_graph_pin(enode.node_index)->to_string().c_str());
}
*/
}
}
}
@ -732,6 +785,14 @@ void LbRouter::expand_node(const LbRRGraph& lb_rr_graph,
}
}
/*
if (nullptr != mode) {
VTR_LOGV(lb_rr_graph.node_pb_graph_pin(cur_node),
"Expand node '%s' by considering mode '%s'\n",
lb_rr_graph.node_pb_graph_pin(cur_node)->to_string().c_str(),
mode->name);
}
*/
expand_edges(lb_rr_graph, mode, cur_node, cur_cost, net_fanout);
}
@ -782,7 +843,7 @@ bool LbRouter::try_expand_nodes(const AtomNetlist& atom_nlist,
const int& isrc,
const int& itarget,
const bool& try_other_modes,
const int& verbosity) {
const bool& verbosity) {
bool is_impossible = false;
do {
@ -790,7 +851,7 @@ bool LbRouter::try_expand_nodes(const AtomNetlist& atom_nlist,
/* No connection possible */
is_impossible = true;
if (verbosity > 3) {
if (true == verbosity) {
//Print detailed debug info
AtomNetId net_id = lb_net_atom_net_ids_[lb_net];
AtomPinId driver_pin = lb_net_atom_source_pins_[lb_net][isrc];

2
openfpga/src/repack/lb_router.h
View File

@ -321,7 +321,7 @@ class LbRouter {
const int& isrc,
const int& itarget,
const bool& try_other_modes,
const int& verbosity);
const bool& verbosity);
bool try_route_net(const LbRRGraph& lb_rr_graph,
const AtomNetlist& atom_nlist,

1
openfpga/test_blif/and_latch.act
View File

@ -3,3 +3,4 @@ b 0.502000 0.197200
clk 0.500000 2.000000
d 0.240200 0.171200
c 0.240200 0.044100
n1 0.240200 0.044100

5
openfpga/test_blif/and_latch.blif
View File

@ -3,9 +3,12 @@
.inputs a b clk
.outputs c d
.latch c d re clk 0
.latch n1 d re clk 0
.names a b c
11 1
.names c n1
1 1
.end