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Separate $alu handling

This commit is contained in:
Eddie Hung 2019-08-09 12:13:32 -07:00
parent 0adf81cb91
commit 31f6d74552
1 changed files with 50 additions and 7 deletions
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57
passes/opt/opt_expr.cc
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@ -642,31 +642,74 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
}
}
if (cell->type.in("$add", "$sub", "$alu"))
if (cell->type.in("$add", "$sub"))
{
RTLIL::SigSpec sig_a = assign_map(cell->getPort("\\A"));
RTLIL::SigSpec sig_b = assign_map(cell->getPort("\\B"));
RTLIL::SigSpec sig_y = cell->getPort("\\Y");
bool ignore_a = cell->type == "$sub" || (cell->type == "$alu" && !cell->getPort("\\BI").is_fully_zero());
bool sub = cell->type == "$sub";
int i;
for (i = 0; i < GetSize(sig_y); i++) {
if (sig_b.at(i, State::Sx) == State::S0 && sig_a.at(i, State::Sx) != State::Sx)
module->connect(sig_y[i], sig_a[i]);
else if (!ignore_a && sig_a.at(i, State::Sx) == State::S0 && sig_b.at(i, State::Sx) != State::Sx)
else if (!sub && sig_a.at(i, State::Sx) == State::S0 && sig_b.at(i, State::Sx) != State::Sx)
module->connect(sig_y[i], sig_b[i]);
else
break;
}
if (i > 0) {
cover_list("opt.opt_expr.fine", "$add", "$sub", "$alu", cell->type.str());
cover_list("opt.opt_expr.fine", "$add", "$sub", cell->type.str());
cell->setPort("\\A", sig_a.extract_end(i));
cell->setPort("\\B", sig_b.extract_end(i));
cell->setPort("\\Y", sig_y.extract_end(i));
if (cell->type == "$alu") {
cell->setPort("\\X", cell->getPort("\\X").extract_end(i));
cell->setPort("\\CO", cell->getPort("\\CO").extract_end(i));
cell->fixup_parameters();
did_something = true;
}
}
if (cell->type == "$alu")
{
RTLIL::SigSpec sig_a = assign_map(cell->getPort("\\A"));
RTLIL::SigSpec sig_b = assign_map(cell->getPort("\\B"));
RTLIL::SigBit sig_ci = assign_map(cell->getPort("\\CI"));
RTLIL::SigBit sig_bi = assign_map(cell->getPort("\\BI"));
RTLIL::SigSpec sig_x = cell->getPort("\\X");
RTLIL::SigSpec sig_y = cell->getPort("\\Y");
RTLIL::SigSpec sig_co = cell->getPort("\\CO");
if (sig_ci.wire || sig_bi.wire)
goto next_cell;
bool sub = (sig_ci == State::S1 && sig_bi == State::S1);
// If not a subtraction, yet there is a carry or B is inverted
// then no optimisation is possible as carry is not constant
if (!sub && (sig_ci != State::S0 || sig_bi != State::S0))
goto next_cell;
int i;
for (i = 0; i < GetSize(sig_y); i++) {
if (sig_b.at(i, State::Sx) == State::S0 && sig_a.at(i, State::Sx) != State::Sx) {
module->connect(sig_x[i], sub ? module->Not(NEW_ID, sig_a[i]).as_bit() : sig_a[i]);
module->connect(sig_y[i], sig_a[i]);
module->connect(sig_co[i], sub ? State::S1 : State::S0);
}
else if (!sub && sig_a.at(i, State::Sx) == State::S0 && sig_b.at(i, State::Sx) != State::Sx) {
module->connect(sig_x[i], sig_b[i]);
module->connect(sig_y[i], sig_b[i]);
module->connect(sig_co[i], State::S0);
}
else
break;
}
if (i > 0) {
cover_list("opt.opt_expr.fine", "$alu", cell->type.str());
cell->setPort("\\A", sig_a.extract_end(i));
cell->setPort("\\B", sig_b.extract_end(i));
cell->setPort("\\X", sig_x.extract_end(i));
cell->setPort("\\Y", sig_y.extract_end(i));
cell->setPort("\\CO", sig_co.extract_end(i));
cell->fixup_parameters();
did_something = true;
}