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Collapse signed*signed or combined nodes via BW.

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This commit is contained in:
nella 2026-05-18 17:21:26 +02:00
parent 73fe179a26
commit 749d6cd8f7
4 changed files with 210 additions and 35 deletions
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35
passes/techmap/arith_tree.cc
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@ -276,19 +276,16 @@ struct ArithTreeWorker {
for (auto &term : macc.terms) {
if (GetSize(term.in_b) != 0) {
// TODO: Baugh-Wooley sign extension for mixed sign and sign*sign cases, don't bail out to non-FMA
if (!opt.fma_fusion)
return false;
if (term.is_signed || !CompressorTree::supports_signedness(term.is_signed, term.is_signed))
return false;
// Preserve term as a multiplicative operand which is expanded into partial products
Operand op;
op.sig = term.in_a;
op.is_signed = false;
op.is_signed = term.is_signed;
op.negate = term.do_subtract;
op.factor_b = term.in_b;
op.factor_b_signed = false;
op.factor_b_signed = term.is_signed;
operands.push_back(op);
continue;
}
@ -313,22 +310,22 @@ struct ArithTreeWorker {
s = module->Not(NEW_ID, s);
pool.push_back({s, 0});
} else {
// Multiplicative operand
// TODO: Negate product instead of factor
auto pps =
CompressorTree::generate_partial_products(module, op.sig, op.factor_b, op.is_signed, op.factor_b_signed, width);
// Multiplicative operand.
auto pps = CompressorTree::generate_partial_products(module, op.sig, op.factor_b, op.is_signed, op.factor_b_signed, width);
if (op.negate) {
for (auto &pp : pps) {
SigSpec inv = module->addWire(NEW_ID, width);
module->addNot(NEW_ID, pp.sig, inv);
pp.sig = inv;
neg_compensation++;
}
if (!op.negate) {
for (auto &pp : pps)
pool.push_back(pp);
continue;
}
for (auto &pp : pps)
pool.push_back(pp);
auto [a_red, b_red] = CompressorTree::reduce_scheduled(module, pps, width, opt.strategy);
SigSpec product = module->addWire(NEW_ID, width);
module->addAdd(NEW_ID, a_red, b_red, product, false);
SigSpec neg = module->addWire(NEW_ID, width);
module->addNot(NEW_ID, product, neg);
pool.push_back({neg, 0});
neg_compensation++;
}
}
@ -380,7 +377,7 @@ struct ArithTreeWorker {
bool any_operand_signed(const std::vector<Operand> &operands)
{
for (auto &op : operands)
if (op.is_signed)
if (op.is_signed || op.factor_b_signed)
return true;
return false;
}