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create duplicate IOFFs if multiple output ports are connected to the same register

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This commit is contained in:
N. Engelhardt 2025-01-31 11:28:57 +01:00
parent 25b400982b
commit 303a386ecc
3 changed files with 93 additions and 15 deletions
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66
techlibs/quicklogic/ql_ioff.cc
View file

@ -29,7 +29,17 @@ struct QlIoffPass : public Pass {
if (!module)
return;
modwalker.setup(module);
pool<RTLIL::Cell *> cells_to_replace;
pool<RTLIL::Cell *> input_ffs;
dict<RTLIL::Wire *, std::vector<Cell*>> output_ffs;
dict<SigBit, pool<SigBit>> output_bit_aliases;
for (Wire* wire : module->wires())
if (wire->port_output) {
output_ffs[wire].resize(wire->width, nullptr);
for (SigBit bit : SigSpec(wire))
output_bit_aliases[modwalker.sigmap(bit)].insert(bit);
}
for (auto cell : module->selected_cells()) {
if (cell->type.in(ID(dffsre), ID(sdffsre))) {
log_debug("Checking cell %s.\n", cell->name.c_str());
@ -53,32 +63,62 @@ struct QlIoffPass : public Pass {
log_debug("not promoting: D has other consumers\n");
continue;
}
cells_to_replace.insert(cell);
continue; // no need to check Q if we already put it on the list
input_ffs.insert(cell);
continue; // prefer input FFs over output FFs
}
SigSpec q = cell->getPort(ID::Q);
log_assert(GetSize(q) == 1);
if (modwalker.has_outputs(q)) {
if (modwalker.has_outputs(q) && !modwalker.has_consumers(q)) {
log_debug("Cell %s is potentially eligible for promotion to output IOFF.\n", cell->name.c_str());
// check that q_sig has no other consumers
pool<ModWalker::PortBit> portbits;
modwalker.get_consumers(portbits, q);
if (GetSize(portbits) > 0) {
log_debug("not promoting: Q has other consumers\n");
continue;
for (SigBit bit : output_bit_aliases[modwalker.sigmap(q)]) {
log_assert(bit.is_wire());
output_ffs[bit.wire][bit.offset] = cell;
}
cells_to_replace.insert(cell);
}
}
}
for (auto cell : cells_to_replace) {
log("Promoting register %s to IOFF.\n", log_signal(cell->getPort(ID::Q)));
for (auto cell : input_ffs) {
log("Promoting register %s to input IOFF.\n", log_signal(cell->getPort(ID::Q)));
cell->type = ID(dff);
cell->unsetPort(ID::E);
cell->unsetPort(ID::R);
cell->unsetPort(ID::S);
}
for (auto & [old_port_output, ioff_cells] : output_ffs) {
if (std::any_of(ioff_cells.begin(), ioff_cells.end(), [](Cell * c) { return c != nullptr; }))
{
// create replacement output wire
RTLIL::Wire* new_port_output = module->addWire(NEW_ID, old_port_output->width);
new_port_output->start_offset = old_port_output->start_offset;
module->swap_names(old_port_output, new_port_output);
std::swap(old_port_output->port_id, new_port_output->port_id);
std::swap(old_port_output->port_input, new_port_output->port_input);
std::swap(old_port_output->port_output, new_port_output->port_output);
std::swap(old_port_output->upto, new_port_output->upto);
std::swap(old_port_output->is_signed, new_port_output->is_signed);
std::swap(old_port_output->attributes, new_port_output->attributes);
// create new output FFs
SigSpec sig_o(old_port_output);
SigSpec sig_n(new_port_output);
for (int i = 0; i < new_port_output->width; i++) {
if (ioff_cells[i]) {
log("Promoting %s to output IOFF.\n", log_signal(sig_n[i]));
RTLIL::Cell *new_cell = module->addCell(NEW_ID, ID(dff));
new_cell->setPort(ID::C, ioff_cells[i]->getPort(ID::C));
new_cell->setPort(ID::D, ioff_cells[i]->getPort(ID::D));
new_cell->setPort(ID::Q, sig_n[i]);
new_cell->set_bool_attribute(ID::keep);
} else {
module->connect(sig_n[i], sig_o[i]);
}
}
}
}
}
} QlIoffPass;

5
techlibs/quicklogic/synth_quicklogic.cc
View file

@ -334,9 +334,10 @@ struct SynthQuickLogicPass : public ScriptPass {
run("opt_lut");
}
if (check_label("iomap", "(for qlf_k6n10f)") && (family == "qlf_k6n10f" || help_mode)) {
if (check_label("iomap", "(for qlf_k6n10f, skip if -noioff)") && (family == "qlf_k6n10f" || help_mode)) {
if (ioff || help_mode) {
run("ql_ioff", "(unless -noioff)");
run("ql_ioff");
run("opt_clean");
}
}