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Fix splitfanout: keep original cell, add new cells to driver db to fix net messup

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This commit is contained in:
Akash Levy 2024-09-29 03:07:07 -07:00
parent 9ecb4e798e
commit 49d948d873
1 changed files with 24 additions and 9 deletions
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33
passes/cmds/splitfanout.cc
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@ -101,11 +101,30 @@ struct SplitfanoutWorker
log_debug("Splitting %s cell %s/%s into %d copies based on fanout\n", log_id(cell->type), log_id(module), log_id(cell), GetSize(bit_users)-1);
int foi = 0;
cell->unsetPort(outport);
int num_new_cells = GetSize(bit_users)-1;
int bit_user_i = num_new_cells;
for (auto bit_user : bit_users)
{
// Create a new cell
IdString new_name = module->uniquify(cell->name.str());
Cell *new_cell = module->addCell(new_name, cell);
// Configure the driver cell
IdString new_name;
Cell *new_cell;
if (bit_user_i-- != 0) { // create a new cell
new_name = module->uniquify(cell->name.str());
new_cell = module->addCell(new_name, cell);
// Add new cell to the bit_users_db
for (auto conn : new_cell->connections()) {
if (!new_cell->input(conn.first)) continue;
for (int i = 0; i < GetSize(conn.second); i++) {
SigBit bit(sigmap(conn.second[i]));
if (!bit_drivers_db.count(bit)) continue;
bit_users_db[bit].insert(tuple<IdString,IdString,int>(new_cell->name,
conn.first, i-std::get<2>(bit_drivers_db[bit])));
}
}
} else { // if last cell, reuse the original cell
new_name = cell->name;
new_cell = cell;
}
// Connect the new cell to the user
if (std::get<1>(bit_user) == IdString()) { // is wire
@ -120,7 +139,6 @@ struct SplitfanoutWorker
else {
Wire *new_wire = module->addWire(NEW_ID, GetSize(outsig));
Cell *target_cell = module->cell(std::get<0>(bit_user));
if (!target_cell) continue; // cell might no longer exist
SigSpec sig = target_cell->getPort(std::get<1>(bit_user));
sig.replace(std::get<2>(bit_user), new_wire);
module->cell(std::get<0>(bit_user))->setPort(std::get<1>(bit_user), sig);
@ -131,14 +149,11 @@ struct SplitfanoutWorker
log_debug(" slice %d: %s => %s\n", foi++, log_id(new_name), log_signal(new_cell->getPort(outport)));
}
// Remove the original cell
module->remove(cell);
// Fix up ports
module->fixup_ports();
// Return the number of new cells created
return GetSize(bit_users)-1;
return num_new_cells;
}
};
@ -153,7 +168,7 @@ struct SplitfanoutPass : public Pass {
log("This command copies selected cells with >1 fanout into cells with fanout 1. It\n");
log("is effectively the opposite of the opt_merge pass.\n");
log("\n");
log("This command operates only on cells with 1 output and no \"bit split\" on that\n");
log("This command operates only on cells with 1 output and no 'bit split' on that\n");
log("output.\n");
log("\n");
}