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author | Eddie Hung <eddie@fpgeh.com> | 2019-08-09 12:13:32 -0700 |
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committer | Eddie Hung <eddie@fpgeh.com> | 2019-08-09 12:13:32 -0700 |
commit | 31f6d745528e1cfc155e65ebb11de9499c0f11e6 (patch) | |
tree | 5389dcc9a83d5af9c0c5506e6495cbefb6137385 /passes/opt | |
parent | 0adf81cb91cc4068cff342bf880ba68b17d183c3 (diff) | |
download | yosys-31f6d745528e1cfc155e65ebb11de9499c0f11e6.tar.gz yosys-31f6d745528e1cfc155e65ebb11de9499c0f11e6.tar.bz2 yosys-31f6d745528e1cfc155e65ebb11de9499c0f11e6.zip |
Separate $alu handling
Diffstat (limited to 'passes/opt')
-rw-r--r-- | passes/opt/opt_expr.cc | 57 |
1 files changed, 50 insertions, 7 deletions
diff --git a/passes/opt/opt_expr.cc b/passes/opt/opt_expr.cc index 5a82b7066..0ddfa5e4c 100644 --- a/passes/opt/opt_expr.cc +++ b/passes/opt/opt_expr.cc @@ -642,31 +642,74 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons } } - if (cell->type.in("$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; } |