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Merge pull request #1994 from YosysHQ/eddie/fix_bug1758

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opt_expr: improve single-bit $and/$or/$xor/$xnor cells; gate cells too
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Eddie Hung 2020-05-14 11:56:22 -07:00 • committed by GitHub
commit 73b7ea713c
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GPG key ID: 4AEE18F83AFDEB23
9 changed files with 562 additions and 30 deletions
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136
passes/opt/opt_expr.cc
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@ -132,7 +132,7 @@ void replace_cell(SigMap &assign_map, RTLIL::Module *module, RTLIL::Cell *cell,
did_something = true;
}
bool group_cell_inputs(RTLIL::Module *module, RTLIL::Cell *cell, bool commutative, SigMap &sigmap)
bool group_cell_inputs(RTLIL::Module *module, RTLIL::Cell *cell, bool commutative, SigMap &sigmap, bool keepdc)
{
IdString b_name = cell->hasPort(ID::B) ? ID::B : ID::A;
@ -156,20 +156,36 @@ bool group_cell_inputs(RTLIL::Module *module, RTLIL::Cell *cell, bool commutativ
int group_idx = GRP_DYN;
RTLIL::SigBit bit_a = bits_a[i], bit_b = bits_b[i];
if (cell->type == ID($or) && (bit_a == RTLIL::State::S1 || bit_b == RTLIL::State::S1))
bit_a = bit_b = RTLIL::State::S1;
if (cell->type == ID($or)) {
if (bit_a == RTLIL::State::S1 || bit_b == RTLIL::State::S1)
bit_a = bit_b = RTLIL::State::S1;
}
else if (cell->type == ID($and)) {
if (bit_a == RTLIL::State::S0 || bit_b == RTLIL::State::S0)
bit_a = bit_b = RTLIL::State::S0;
}
else if (!keepdc) {
if (cell->type == ID($xor)) {
if (bit_a == bit_b)
bit_a = bit_b = RTLIL::State::S0;
}
else if (cell->type == ID($xnor)) {
if (bit_a == bit_b)
bit_a = bit_b = RTLIL::State::S1; // For consistency with gate-level which does $xnor -> $_XOR_ + $_NOT_
}
}
if (cell->type == ID($and) && (bit_a == RTLIL::State::S0 || bit_b == RTLIL::State::S0))
bit_a = bit_b = RTLIL::State::S0;
if (bit_a.wire == NULL && bit_b.wire == NULL)
group_idx = GRP_CONST_AB;
else if (bit_a.wire == NULL)
group_idx = GRP_CONST_A;
else if (bit_b.wire == NULL && commutative)
group_idx = GRP_CONST_A, std::swap(bit_a, bit_b);
else if (bit_b.wire == NULL)
group_idx = GRP_CONST_B;
bool def = (bit_a != State::Sx && bit_a != State::Sz && bit_b != State::Sx && bit_b != State::Sx);
if (def || !keepdc) {
if (bit_a.wire == NULL && bit_b.wire == NULL)
group_idx = GRP_CONST_AB;
else if (bit_a.wire == NULL)
group_idx = GRP_CONST_A;
else if (bit_b.wire == NULL && commutative)
group_idx = GRP_CONST_A, std::swap(bit_a, bit_b);
else if (bit_b.wire == NULL)
group_idx = GRP_CONST_B;
}
grouped_bits[group_idx][std::pair<RTLIL::SigBit, RTLIL::SigBit>(bit_a, bit_b)].insert(bits_y[i]);
}
@ -186,26 +202,77 @@ bool group_cell_inputs(RTLIL::Module *module, RTLIL::Cell *cell, bool commutativ
if (grouped_bits[i].empty())
continue;
RTLIL::Wire *new_y = module->addWire(NEW_ID, GetSize(grouped_bits[i]));
RTLIL::SigSpec new_y = module->addWire(NEW_ID, GetSize(grouped_bits[i]));
RTLIL::SigSpec new_a, new_b;
RTLIL::SigSig new_conn;
for (auto &it : grouped_bits[i]) {
for (auto &bit : it.second) {
new_conn.first.append(bit);
new_conn.second.append(RTLIL::SigBit(new_y, new_a.size()));
new_conn.second.append(new_y[new_a.size()]);
}
new_a.append(it.first.first);
new_b.append(it.first.second);
}
if (cell->type.in(ID($and), ID($or)) && i == GRP_CONST_A) {
if (!keepdc) {
if (cell->type == ID($and))
new_a.replace(dict<SigBit,SigBit>{{State::Sx, State::S0}, {State::Sz, State::S0}}, &new_b);
else if (cell->type == ID($or))
new_a.replace(dict<SigBit,SigBit>{{State::Sx, State::S1}, {State::Sz, State::S1}}, &new_b);
else log_abort();
}
log_debug(" Direct Connection: %s (%s with %s)\n", log_signal(new_b), log_id(cell->type), log_signal(new_a));
module->connect(new_y, new_b);
module->connect(new_conn);
continue;
}
if (cell->type.in(ID($xor), ID($xnor)) && i == GRP_CONST_A) {
SigSpec undef_a, undef_y, undef_b;
SigSpec def_y, def_a, def_b;
for (int i = 0; i < GetSize(new_y); i++) {
bool undef = new_a[i] == State::Sx || new_a[i] == State::Sz;
if (!keepdc && (undef || new_a[i] == new_b[i])) {
undef_a.append(new_a[i]);
if (cell->type == ID($xor))
undef_b.append(State::S0);
// For consistency since simplemap does $xnor -> $_XOR_ + $_NOT_
else if (cell->type == ID($xnor))
undef_b.append(State::S1);
else log_abort();
undef_y.append(new_y[i]);
}
else if (new_a[i] == State::S0 || new_a[i] == State::S1) {
undef_a.append(new_a[i]);
if (cell->type == ID($xor))
undef_b.append(new_a[i] == State::S1 ? module->Not(NEW_ID, new_b[i]).as_bit() : new_b[i]);
else if (cell->type == ID($xnor))
undef_b.append(new_a[i] == State::S1 ? new_b[i] : module->Not(NEW_ID, new_b[i]).as_bit());
else log_abort();
undef_y.append(new_y[i]);
}
else {
def_a.append(new_a[i]);
def_b.append(new_b[i]);
def_y.append(new_y[i]);
}
}
if (!undef_y.empty()) {
log_debug(" Direct Connection: %s (%s with %s)\n", log_signal(undef_b), log_id(cell->type), log_signal(undef_a));
module->connect(undef_y, undef_b);
if (def_y.empty()) {
module->connect(new_conn);
continue;
}
}
new_a = std::move(def_a);
new_b = std::move(def_b);
new_y = std::move(def_y);
}
RTLIL::Cell *c = module->addCell(NEW_ID, cell->type);
c->setPort(ID::A, new_a);
@ -219,7 +286,7 @@ bool group_cell_inputs(RTLIL::Module *module, RTLIL::Cell *cell, bool commutativ
}
c->setPort(ID::Y, new_y);
c->parameters[ID::Y_WIDTH] = new_y->width;
c->parameters[ID::Y_WIDTH] = GetSize(new_y);
c->check();
module->connect(new_conn);
@ -476,13 +543,13 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
}
}
if (detect_const_and && (found_zero || found_inv)) {
if (detect_const_and && (found_zero || found_inv || (found_undef && consume_x))) {
cover("opt.opt_expr.const_and");
replace_cell(assign_map, module, cell, "const_and", ID::Y, RTLIL::State::S0);
goto next_cell;
}
if (detect_const_or && (found_one || found_inv)) {
if (detect_const_or && (found_one || found_inv || (found_undef && consume_x))) {
cover("opt.opt_expr.const_or");
replace_cell(assign_map, module, cell, "const_or", ID::Y, RTLIL::State::S1);
goto next_cell;
@ -499,6 +566,22 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
{
SigBit sig_a = assign_map(cell->getPort(ID::A));
SigBit sig_b = assign_map(cell->getPort(ID::B));
if (!keepdc && (sig_a == sig_b || sig_a == State::Sx || sig_a == State::Sz || sig_b == State::Sx || sig_b == State::Sz)) {
if (cell->type.in(ID($xor), ID($_XOR_))) {
cover("opt.opt_expr.const_xor");
replace_cell(assign_map, module, cell, "const_xor", ID::Y, RTLIL::State::S0);
goto next_cell;
}
if (cell->type.in(ID($xnor), ID($_XNOR_))) {
cover("opt.opt_expr.const_xnor");
// For consistency since simplemap does $xnor -> $_XOR_ + $_NOT_
int width = cell->getParam(ID::Y_WIDTH).as_int();
replace_cell(assign_map, module, cell, "const_xnor", ID::Y, SigSpec(RTLIL::State::S1, width));
goto next_cell;
}
log_abort();
}
if (!sig_a.wire)
std::swap(sig_a, sig_b);
if (sig_b == State::S0 || sig_b == State::S1) {
@ -550,7 +633,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
if (do_fine)
{
if (cell->type.in(ID($not), ID($pos), ID($and), ID($or), ID($xor), ID($xnor)))
if (group_cell_inputs(module, cell, true, assign_map))
if (group_cell_inputs(module, cell, true, assign_map, keepdc))
goto next_cell;
if (cell->type.in(ID($logic_not), ID($logic_and), ID($logic_or), ID($reduce_or), ID($reduce_and), ID($reduce_bool)))
@ -904,8 +987,10 @@ skip_fine_alu:
if (input.match("01")) ACTION_DO_Y(1);
if (input.match("10")) ACTION_DO_Y(1);
if (input.match("11")) ACTION_DO_Y(0);
if (input.match(" *")) ACTION_DO_Y(x);
if (input.match("* ")) ACTION_DO_Y(x);
if (consume_x) {
if (input.match(" *")) ACTION_DO_Y(0);
if (input.match("* ")) ACTION_DO_Y(0);
}
}
if (cell->type == ID($_MUX_)) {
@ -1088,7 +1173,7 @@ skip_fine_alu:
goto next_cell;
}
if (!keepdc)
if (consume_x)
{
bool identity_wrt_a = false;
bool identity_wrt_b = false;
@ -1980,11 +2065,12 @@ struct OptExprPass : public Pass {
do {
do {
did_something = false;
replace_const_cells(design, module, false, mux_undef, mux_bool, do_fine, keepdc, clkinv);
replace_const_cells(design, module, false /* consume_x */, mux_undef, mux_bool, do_fine, keepdc, clkinv);
if (did_something)
design->scratchpad_set_bool("opt.did_something", true);
} while (did_something);
replace_const_cells(design, module, true, mux_undef, mux_bool, do_fine, keepdc, clkinv);
if (!keepdc)
replace_const_cells(design, module, true /* consume_x */, mux_undef, mux_bool, do_fine, keepdc, clkinv);
if (did_something)
design->scratchpad_set_bool("opt.did_something", true);
} while (did_something);