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abc9 to replace $_NOT_ with $lut

This commit is contained in:
Eddie Hung 2019-02-19 12:30:20 -08:00
parent e79df5e70e
commit 8158bc3f99
1 changed files with 39 additions and 4 deletions
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43
passes/techmap/abc9.cc
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@ -579,11 +579,46 @@ void abc9_module(RTLIL::Design *design, RTLIL::Module *current_module, std::stri
module->connect(conn); module->connect(conn);
continue; continue;
} }
if (c->type == "\\NOT") { if (c->type == "$_NOT_") {
RTLIL::Cell *cell = module->addCell(remap_name(c->name), "$_NOT_"); RTLIL::Cell *cell;
RTLIL::SigBit a_bit = c->getPort("\\A").as_bit();
RTLIL::SigBit y_bit = c->getPort("\\Y").as_bit();
if (!lut_costs.empty()) {
// ABC can return NOT gates that drive POs
if (a_bit.wire->port_input) {
// If it's a NOT gate that comes from a primary input directly
// then implement it using a LUT
cell = module->addLut(remap_name(stringf("%s_lut", c->name.c_str())),
RTLIL::SigBit(module->wires_[remap_name(a_bit.wire->name)], a_bit.offset),
RTLIL::SigBit(module->wires_[remap_name(y_bit.wire->name)], y_bit.offset),
1);
}
else {
// Otherwise, clone the driving LUT to guarantee that we
// won't increase the max logic depth
// (TODO: Optimise by not cloning unless will increase depth)
RTLIL::Cell* driver = mapped_mod->cell(stringf("%s_lut", a_bit.wire->name.c_str()));
log_assert(driver);
auto driver_a = driver->getPort("\\A").chunks();
for (auto &chunk : driver_a)
chunk.wire = module->wires_[remap_name(chunk.wire->name)];
RTLIL::Const driver_lut = driver->getParam("\\LUT");
for (auto &b : driver_lut.bits) {
if (b == RTLIL::State::S0) b = RTLIL::State::S1;
else if (b == RTLIL::State::S1) b = RTLIL::State::S0;
}
cell = module->addLut(remap_name(stringf("%s_lut", c->name.c_str())),
driver_a,
RTLIL::SigBit(module->wires_[remap_name(y_bit.wire->name)], y_bit.offset),
driver_lut);
}
}
else {
cell = module->addCell(remap_name(c->name), "$_NOT_");
cell->setPort("\\A", RTLIL::SigBit(module->wires_[remap_name(a_bit.wire->name)], a_bit.offset));
cell->setPort("\\Y", RTLIL::SigBit(module->wires_[remap_name(y_bit.wire->name)], y_bit.offset));
}
if (markgroups) cell->attributes["\\abcgroup"] = map_autoidx; if (markgroups) cell->attributes["\\abcgroup"] = map_autoidx;
cell->setPort("\\A", RTLIL::SigSpec(module->wires_[remap_name(c->getPort("\\A").as_wire()->name)]));
cell->setPort("\\Y", RTLIL::SigSpec(module->wires_[remap_name(c->getPort("\\Y").as_wire()->name)]));
design->select(module, cell); design->select(module, cell);
continue; continue;
} }