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opt_expr: optimise 1-bit $xor or $_XOR_ with constant input

This commit is contained in:
Eddie Hung 2020-03-19 16:33:54 -07:00
parent a0cc795e85
commit ee5995641e
1 changed files with 14 additions and 1 deletions
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15
passes/opt/opt_expr.cc
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@ -496,6 +496,19 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
} }
} }
if (cell->type == ID($_XOR_) || (cell->type == ID($xor) && GetSize(cell->getPort(ID::A)) == 1 && GetSize(cell->getPort(ID::B)) == 1 && !cell->getParam(ID(A_SIGNED)).as_bool()))
{
SigBit sig_a = assign_map(cell->getPort(ID::A));
SigBit sig_b = assign_map(cell->getPort(ID::B));
if (!sig_a.wire)
std::swap(sig_a, sig_b);
if (sig_b == State::S0 || sig_b == State::S1) {
cover("opt.opt_expr.xor_buffer");
replace_cell(assign_map, module, cell, "xor_buffer", ID::Y, sig_b == State::S1 ? module->NotGate(NEW_ID, sig_a) : sig_a);
goto next_cell;
}
}
if (cell->type.in(ID($reduce_and), ID($reduce_or), ID($reduce_bool), ID($reduce_xor), ID($reduce_xnor), ID($neg)) && if (cell->type.in(ID($reduce_and), ID($reduce_or), ID($reduce_bool), ID($reduce_xor), ID($reduce_xnor), ID($neg)) &&
GetSize(cell->getPort(ID::A)) == 1 && GetSize(cell->getPort(ID::Y)) == 1) GetSize(cell->getPort(ID::A)) == 1 && GetSize(cell->getPort(ID::Y)) == 1)
{ {
@ -1590,7 +1603,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
} }
int const_bit_set = get_highest_hot_index(const_sig); int const_bit_set = get_highest_hot_index(const_sig);
if(const_bit_set >= var_width) if (const_bit_set >= var_width)
{ {
string cmp_name; string cmp_name;
if (cmp_type == ID($lt) || cmp_type == ID($le)) if (cmp_type == ID($lt) || cmp_type == ID($le))