diff options
| -rw-r--r-- | kernel/rtlil.cc | 3 | ||||
| -rw-r--r-- | passes/opt/wreduce.cc | 71 |
2 files changed, 73 insertions, 1 deletions
diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc index 8404db5e9..d4aebcda9 100644 --- a/kernel/rtlil.cc +++ b/kernel/rtlil.cc @@ -2410,6 +2410,9 @@ void RTLIL::Cell::fixup_parameters(bool set_a_signed, bool set_b_signed) if (connections_.count("\\Y")) parameters["\\Y_WIDTH"] = GetSize(connections_["\\Y"]); + if (connections_.count("\\Q")) + parameters["\\WIDTH"] = GetSize(connections_["\\Q"]); + check(); } diff --git a/passes/opt/wreduce.cc b/passes/opt/wreduce.cc index 8063b86a6..3aa916ec2 100644 --- a/passes/opt/wreduce.cc +++ b/passes/opt/wreduce.cc @@ -38,7 +38,8 @@ struct WreduceConfig "$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx", "$lt", "$le", "$eq", "$ne", "$eqx", "$nex", "$ge", "$gt", "$add", "$sub", "$mul", // "$div", "$mod", "$pow", - "$mux", "$pmux" + "$mux", "$pmux", + "$dff", "$adff" }); } }; @@ -134,6 +135,71 @@ struct WreduceWorker module->connect(sig_y.extract(n_kept, n_removed), sig_removed); } + void run_cell_dff(Cell *cell) + { + // Reduce size of FF if inputs are just sign/zero extended or output bit is not used + + SigSpec sig_d = mi.sigmap(cell->getPort("\\D")); + SigSpec sig_q = mi.sigmap(cell->getPort("\\Q")); + + int width_before = GetSize(sig_q); + + if (width_before == 0) + return; + + bool zero_ext = sig_d[GetSize(sig_d)-1] == State::S0; + bool sign_ext = !zero_ext; + + for (int i = GetSize(sig_q)-1; i >= 0; i--) + { + if (zero_ext && sig_d[i] == State::S0) { + module->connect(sig_q[i], State::S0); + sig_d.remove(i); + sig_q.remove(i); + continue; + } + + if (sign_ext && i > 0 && sig_d[i] == sig_d[i-1]) { + module->connect(sig_q[i], sig_q[i-1]); + sig_d.remove(i); + sig_q.remove(i); + continue; + } + + auto info = mi.query(sig_q[i]); + if (!info->is_output && GetSize(info->ports) <= 1 && !keep_bits.count(mi.sigmap(sig_q[i]))) { + sig_d.remove(i); + sig_q.remove(i); + zero_ext = false; + sign_ext = false; + continue; + } + + break; + } + + if (width_before == GetSize(sig_q)) + return; + + if (GetSize(sig_q) == 0) { + log("Removed cell %s.%s (%s).\n", log_id(module), log_id(cell), log_id(cell->type)); + return; + } + + log("Removed top %d bits (of %d) from mux cell %s.%s (%s).\n", width_before - GetSize(sig_q), width_before, + log_id(module), log_id(cell), log_id(cell->type)); + + for (auto bit : sig_d) + work_queue_bits.insert(bit); + + for (auto bit : sig_q) + work_queue_bits.insert(bit); + + cell->setPort("\\D", sig_d); + cell->setPort("\\Q", sig_q); + cell->fixup_parameters(); + } + void run_reduce_inport(Cell *cell, char port, int max_port_size, bool &port_signed, bool &did_something) { port_signed = cell->getParam(stringf("\\%c_SIGNED", port)).as_bool(); @@ -176,6 +242,9 @@ struct WreduceWorker if (cell->type.in("$mux", "$pmux")) return run_cell_mux(cell); + if (cell->type.in("$dff", "$adff")) + return run_cell_dff(cell); + SigSpec sig = mi.sigmap(cell->getPort("\\Y")); if (sig.has_const()) |