Remove the quadratic bookkeeping that dominated parsing large hierarc… - #648
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…hical netlists Two linear scans in the netlist core turned the Verilog parser quadratic on hierarchical netlists (OpenTitan Earl Grey: 25,906 modules, 1.86 million nets created and 460k merged away, 2.3 million endpoints): - Deleting a gate, net, or module removed it from the netlist's (and the module's) object vector with a linear std::find. The vectors now keep the position of every element in a map, and removal is a swap with the last element in constant time (utils::indexed_vector_push_back / erase). - Module::is_parent_module_of walked this module's whole subtree; for the top-level modules that is the entire hierarchy, once per endpoint whenever module nets are recomputed. It now walks up the parent chain of the queried module, bounded by the hierarchy depth. Module::set_parent_module detaches the module and updates its parent before the old parent re-checks its nets, which the upward walk requires. Release parse of the 216 MB Earl Grey netlist: 709 s -> 31 s. All netlist, module, net, gate, and grouping tests pass. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
julianspeith
enabled auto-merge (squash)
September 10, 2026 09:42
julianspeith
disabled auto-merge
September 10, 2026 09:42
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…hical netlists
Two linear scans in the netlist core turned the Verilog parser quadratic on hierarchical netlists (OpenTitan Earl Grey: 25,906 modules, 1.86 million nets created and 460k merged away, 2.3 million endpoints):
Deleting a gate, net, or module removed it from the netlist's (and the module's) object vector with a linear std::find. The vectors now keep the position of every element in a map, and removal is a swap with the last element in constant time (utils::indexed_vector_push_back / erase).
Module::is_parent_module_of walked this module's whole subtree; for the top-level modules that is the entire hierarchy, once per endpoint whenever module nets are recomputed. It now walks up the parent chain of the queried module, bounded by the hierarchy depth. Module::set_parent_module detaches the module and updates its parent before the old parent re-checks its nets, which the upward walk requires.
Release parse of the 216 MB Earl Grey netlist: 709 s -> 31 s. All netlist, module, net, gate, and grouping tests pass.