diff options
Diffstat (limited to 'mistral/pack.cc')
| -rw-r--r-- | mistral/pack.cc | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/mistral/pack.cc b/mistral/pack.cc index 98ab22bf..ef3b3887 100644 --- a/mistral/pack.cc +++ b/mistral/pack.cc @@ -342,12 +342,52 @@ struct MistralPacker } } + void constrain_lutram() + { + // We form clusters based on both read and write address; as both being the same makes it more likely these + // cells should be packed together, too. + // This makes things easier for the placement legaliser to deal with RAM in LAB-compatible blocks without + // over-constraining things + idict<dict<IdString, IdString>> mlab_keys; + std::vector<std::vector<CellInfo *>> mlab_groups; + for (auto &cell : ctx->cells) { + CellInfo *ci = cell.second.get(); + if (ci->type != id_MISTRAL_MLAB) + continue; + auto key = ctx->get_mlab_key(ci, true); + int key_idx = mlab_keys(key); + if (key_idx >= int(mlab_groups.size())) + mlab_groups.resize(key_idx + 1); + mlab_groups.at(key_idx).push_back(ci); + } + // Combine into clusters + size_t cluster_size = 20; + for (auto &group : mlab_groups) { + for (size_t i = 0; i < group.size(); i++) { + CellInfo *ci = group.at(i); + CellInfo *base = group.at((i / cluster_size) * cluster_size); + int cell_index = int(i) % cluster_size; + int alm = i / 2; + int alm_cell = i % 2; + ci->constr_abs_z = true; + ci->constr_z = alm * 6 + alm_cell; + if (cell_index != 0) { + // Not the root of a cluster + base->constr_children.push_back(ci); + ci->constr_x = 0; + ci->constr_y = 0; + } + } + } + } + void run() { init_constant_nets(); pack_constants(); pack_io(); constrain_carries(); + constrain_lutram(); } }; }; // namespace |