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[VPR][Pack] Breaking Ties When Placing Primitives #3118

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[VPR][Pack] Breaking Ties When Placing Primitives #3118

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fcecc01
[vpr][pack] compare block name to break tie when placing primitives
amin1377 Jun 6, 2025
e804483
make format
amin1377 Jun 6, 2025
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19 changes: 18 additions & 1 deletion vpr/src/pack/cluster_placement.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -261,12 +261,29 @@ bool get_next_primitive_list(t_intra_cluster_placement_stats* cluster_placement_

// if the cost is lower than the best, or is equal to the best but this
// primitive is more available in the cluster mark it as the best primitive
if (cost < lowest_cost || (found_best && best->second && cost == lowest_cost && it->second->pb_graph_node->total_primitive_count > best->second->pb_graph_node->total_primitive_count)) {
bool update_best = false;
if (cost < lowest_cost) {
update_best = true;
} else if (found_best && best->second && cost == lowest_cost) {
if (it->second->pb_graph_node->total_primitive_count > best->second->pb_graph_node->total_primitive_count) {
update_best = true;
} else if (it->second->pb_graph_node->total_primitive_count == best->second->pb_graph_node->total_primitive_count) {
// TODO: This is a hack to break a tie when choosing the best block for a primitive. Without this, the packing results
// can change if the order of pb_types defined in the architecture file changes.
VTR_ASSERT(it->second->pb_graph_node->pb_type->name != best->second->pb_graph_node->pb_type->name);
if (it->second->pb_graph_node->hierarchical_type_name() < best->second->pb_graph_node->hierarchical_type_name()) {
update_best = true;
}
}
}

if (update_best) {
lowest_cost = cost;
best = it;
best_pb_type_index = i;
found_best = true;
}

++it;
}
}
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