pattern shiftmul // // Optimize mul+shift pairs that result from expressions such as foo[s*W+:W] // state shamt match shift select shift->type.in($shift, $shiftx, $shr) endmatch code shamt shamt = port(shift, \B); if (shamt.empty()) reject; if (shamt[GetSize(shamt)-1] == State::S0) { do { shamt.remove(GetSize(shamt)-1); if (shamt.empty()) reject; } while (shamt[GetSize(shamt)-1] == State::S0); } else if (shift->type.in($shift, $shiftx) && param(shift, \B_SIGNED).as_bool()) { reject; } if (GetSize(shamt) > 20) reject; endcode match mul select mul->type.in($mul) select port(mul, \A).is_fully_const() || port(mul, \B).is_fully_const() index port(mul, \Y) === shamt filter !param(mul, \A_SIGNED).as_bool() endmatch code { IdString const_factor_port = port(mul, \A).is_fully_const() ? \A : \B; Const const_factor_cnst = port(mul, const_factor_port).as_const(); int const_factor = const_factor_cnst.as_int(); if (GetSize(const_factor_cnst) == 0) reject; if (GetSize(const_factor_cnst) > 20) reject; if (GetSize(port(shift, \Y)) > const_factor) reject; int factor_bits = ceil_log2(const_factor); SigSpec mul_din = port(mul, const_factor_port == \A ? \B : \A); if (GetSize(shamt) < factor_bits+GetSize(mul_din)) reject; did_something = true; log("shiftmul pattern in %s: shift=%s, mul=%s\n", log_id(module), log_id(shift), log_id(mul)); int new_const_factor = 1 << factor_bits; SigSpec padding(State::Sx, new_const_factor-const_factor); SigSpec old_a = port(shift, \A), new_a; int trunc = 0; if (GetSize(old_a) % const_factor != 0) { trunc = const_factor - GetSize(old_a) % const_factor; old_a.append(SigSpec(State::Sx, trunc)); } for (int i = 0; i*const_factor < GetSize(old_a); i++) { SigSpec slice = old_a.extract(i*const_factor, const_factor); new_a.append(slice); new_a.append(padding); } if (trunc > 0) new_a.remove(GetSize(new_a)-trunc, trunc); SigSpec new_b = {mul_din, SigSpec(State::S0, factor_bits)}; if (param(shift, \B_SIGNED).as_bool()) new_b.append(State::S0); shift->setPort(\A, new_a); shift->setParam(\A_WIDTH, GetSize(new_a)); shift->setPort(\B, new_b); shift->setParam(\B_WIDTH, GetSize(new_b)); blacklist(shift); accept; } endcode