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yosys/passes/cmds/xprop.cc

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/*
* yosys -- Yosys Open SYnthesis Suite
*
* Copyright (C) 2022 Jannis Harder <jix@yosyshq.com> <me@jix.one>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#include "kernel/celltypes.h"
#include "kernel/ffinit.h"
#include "kernel/ff.h"
#include "kernel/modtools.h"
#include "kernel/sigtools.h"
#include "kernel/utils.h"
#include "kernel/yosys.h"
#include <deque>
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
struct XpropOptions
{
bool split_inputs = false;
bool split_outputs = false;
bool split_public = false;
bool assume_encoding = false;
bool assert_encoding = false;
bool assume_def_inputs = false;
bool required = false;
bool formal = false;
bool debug_asserts = false;
};
struct XpropWorker
{
struct EncodedBit {
SigBit is_0, is_1, is_x;
bool driven;
};
struct EncodedSig {
SigSpec is_0, is_1, is_x;
Module *module;
void invert() { std::swap(is_0, is_1); }
void auto_0() { connect_0(module->Not(NEW_ID, module->Or(NEW_ID, is_1, is_x))); }
void auto_1() { connect_1(module->Not(NEW_ID, module->Or(NEW_ID, is_0, is_x))); }
void auto_x() { connect_x(module->Not(NEW_ID, module->Or(NEW_ID, is_0, is_1))); }
void connect_0(SigSpec sig) { module->connect(is_0, sig); }
void connect_1(SigSpec sig) { module->connect(is_1, sig); }
void connect_x(SigSpec sig) { module->connect(is_x, sig); }
void connect_1_under_x(SigSpec sig) { connect_1(module->And(NEW_ID, sig, module->Not(NEW_ID, is_x))); }
void connect_0_under_x(SigSpec sig) { connect_0(module->And(NEW_ID, sig, module->Not(NEW_ID, is_x))); }
void connect_x_under_0(SigSpec sig) { connect_x(module->And(NEW_ID, sig, module->Not(NEW_ID, is_0))); }
void connect_as_bool() {
int width = GetSize(is_0);
if (width <= 1)
return;
module->connect(is_0.extract(1, width - 1), Const(State::S1, width - 1));
module->connect(is_1.extract(1, width - 1), Const(State::S0, width - 1));
module->connect(is_x.extract(1, width - 1), Const(State::S0, width - 1));
is_0 = is_0[0];
is_1 = is_1[0];
is_x = is_x[0];
}
int size() const { return is_0.size(); }
};
Module *module;
XpropOptions options;
ModWalker modwalker;
SigMap &sigmap;
FfInitVals initvals;
pool<SigBit> maybe_x_bits;
dict<SigBit, EncodedBit> encoded_bits;
pool<Cell *> pending_cells;
std::deque<Cell *> pending_cell_queue;
XpropWorker(Module *module, XpropOptions options) :
module(module), options(options),
modwalker(module->design), sigmap(modwalker.sigmap)
{
modwalker.setup(module);
initvals.set(&modwalker.sigmap, module);
maybe_x_bits.insert(State::Sx);
for (auto cell : module->cells()) {
pending_cells.insert(cell);
pending_cell_queue.push_back(cell);
}
if (!options.assume_def_inputs) {
for (auto port : module->ports) {
auto wire = module->wire(port);
if (wire->port_input)
mark_maybe_x(SigSpec(wire));
}
}
}
bool maybe_x(SigBit bit)
{
return maybe_x_bits.count(sigmap(bit));
}
bool maybe_x(const SigSpec &sig)
{
for (auto bit : sig)
if (maybe_x(bit)) return true;
return false;
}
bool ports_maybe_x(Cell *cell)
{
for (auto &conn : cell->connections())
if (maybe_x(conn.second))
return true;
return false;
}
bool inputs_maybe_x(Cell *cell)
{
for (auto &conn : cell->connections())
if (cell->input(conn.first) && maybe_x(conn.second))
return true;
return false;
}
void mark_maybe_x(SigBit bit)
{
sigmap.apply(bit);
if (!maybe_x_bits.insert(bit).second)
return;
auto it = modwalker.signal_consumers.find(bit);
if (it == modwalker.signal_consumers.end())
return;
for (auto &consumer : it->second)
if (pending_cells.insert(consumer.cell).second)
pending_cell_queue.push_back(consumer.cell);
}
void mark_maybe_x(const SigSpec &sig)
{
for (auto bit : sig)
mark_maybe_x(bit);
}
void mark_outputs_maybe_x(Cell *cell)
{
for (auto &conn : cell->connections())
if (cell->output(conn.first))
mark_maybe_x(conn.second);
}
EncodedSig encoded(SigSpec sig, bool driving = false)
{
EncodedSig result;
SigSpec invert;
if (driving)
result.module = module;
int new_bits = 0;
sigmap.apply(sig);
for (auto bit : sig) {
if (!bit.is_wire())
continue;
else if (!maybe_x(bit) && !driving)
invert.append(bit);
else if (!encoded_bits.count(bit)) {
new_bits += 1;
encoded_bits.emplace(bit, {
State::Sm, State::Sm, State::Sm, false
});
}
}
if (!invert.empty() && !driving)
invert = module->Not(NEW_ID, invert);
EncodedSig new_sigs;
if (new_bits > 0) {
new_sigs.is_0 = module->addWire(NEW_ID, new_bits);
new_sigs.is_1 = module->addWire(NEW_ID, new_bits);
new_sigs.is_x = module->addWire(NEW_ID, new_bits);
}
int invert_pos = 0;
int new_pos = 0;
SigSpec driven_orig;
EncodedSig driven_enc;
SigSig driven_never_x;
for (auto bit : sig)
{
if (!bit.is_wire()) {
result.is_0.append(bit == State::S0 ? State::S1 : State::S0);
result.is_1.append(bit == State::S1 ? State::S1 : State::S0);
result.is_x.append(bit == State::Sx ? State::S1 : State::S0);
continue;
} else if (!maybe_x(bit) && !driving) {
result.is_0.append(invert[invert_pos++]);
result.is_1.append(bit);
result.is_x.append(State::S0);
continue;
}
auto &enc = encoded_bits.at(bit);
if (enc.is_0 == State::Sm) {
enc.is_0 = new_sigs.is_0[new_pos];
enc.is_1 = new_sigs.is_1[new_pos];
enc.is_x = new_sigs.is_x[new_pos];
new_pos++;
}
if (driving) {
log_assert(!enc.driven);
enc.driven = true;
if (maybe_x(bit)) {
driven_orig.append(bit);
driven_enc.is_0.append(enc.is_0);
driven_enc.is_1.append(enc.is_1);
driven_enc.is_x.append(enc.is_x);
} else {
driven_never_x.first.append(bit);
driven_never_x.second.append(enc.is_1);
}
}
result.is_0.append(enc.is_0);
result.is_1.append(enc.is_1);
result.is_x.append(enc.is_x);
}
if (!driven_orig.empty()) {
auto decoder = module->addBwmux(NEW_ID, driven_enc.is_1, Const(State::Sx, GetSize(driven_orig)), driven_enc.is_x, driven_orig);
decoder->set_bool_attribute(ID::xprop_decoder);
}
if (!driven_never_x.first.empty()) {
module->connect(driven_never_x);
}
if (driving && (options.assert_encoding || options.assume_encoding)) {
auto not_0 = module->Not(NEW_ID, result.is_0);
auto not_1 = module->Not(NEW_ID, result.is_1);
auto not_x = module->Not(NEW_ID, result.is_x);
auto valid = module->ReduceAnd(NEW_ID, {
module->Eq(NEW_ID, result.is_0, module->And(NEW_ID, not_1, not_x)),
module->Eq(NEW_ID, result.is_1, module->And(NEW_ID, not_0, not_x)),
module->Eq(NEW_ID, result.is_x, module->And(NEW_ID, not_0, not_1)),
});
if (options.assert_encoding)
module->addAssert(NEW_ID_SUFFIX("xprop_enc"), valid, State::S1);
else
module->addAssume(NEW_ID_SUFFIX("xprop_enc"), valid, State::S1);
if (options.debug_asserts) {
auto bad_bits = module->Bweqx(NEW_ID, {result.is_0, result.is_1, result.is_x}, Const(State::Sx, GetSize(result) * 3));
module->addAssert(NEW_ID_SUFFIX("xprop_debug"), module->LogicNot(NEW_ID, bad_bits), State::S1);
}
}
return result;
}
void mark_all_maybe_x()
{
while (!pending_cell_queue.empty()) {
Cell *cell = pending_cell_queue.front();
pending_cell_queue.pop_front();
pending_cells.erase(cell);
mark_maybe_x(cell);
}
}
void mark_maybe_x(Cell *cell) {
if (cell->type.in(ID($bweqx), ID($eqx), ID($nex), ID($initstate), ID($assert), ID($assume), ID($cover), ID($anyseq), ID($anyconst)))
return;
if (cell->type.in(ID($pmux))) {
mark_outputs_maybe_x(cell);
return;
}
if (RTLIL::builtin_ff_cell_types().count(cell->type) || cell->type == ID($anyinit)) {
FfData ff(&initvals, cell);
if (cell->type != ID($anyinit))
for (int i = 0; i < ff.width; i++)
if (ff.val_init[i] == State::Sx)
mark_maybe_x(ff.sig_q[i]);
for (int i = 0; i < ff.width; i++)
if (maybe_x(ff.sig_d[i]))
mark_maybe_x(ff.sig_q[i]);
if ((ff.has_clk || ff.has_gclk) && !ff.has_ce && !ff.has_aload && !ff.has_srst && !ff.has_arst && !ff.has_sr)
return;
}
if (cell->type == ID($not)) {
auto &sig_y = cell->getPort(ID::Y);
auto sig_a = cell->getPort(ID::A); sig_a.extend_u0(GetSize(sig_y), cell->getParam(ID::A_SIGNED).as_bool());
for (int i = 0; i < GetSize(sig_y); i++)
if (maybe_x(sig_a[i]))
mark_maybe_x(sig_y[i]);
return;
}
if (cell->type.in(ID($and), ID($or), ID($xor), ID($xnor))) {
auto &sig_y = cell->getPort(ID::Y);
auto sig_a = cell->getPort(ID::A); sig_a.extend_u0(GetSize(sig_y), cell->getParam(ID::A_SIGNED).as_bool());
auto sig_b = cell->getPort(ID::B); sig_b.extend_u0(GetSize(sig_y), cell->getParam(ID::B_SIGNED).as_bool());
for (int i = 0; i < GetSize(sig_y); i++)
if (maybe_x(sig_a[i]) || maybe_x(sig_b[i]))
mark_maybe_x(sig_y[i]);
return;
}
if (cell->type.in(ID($bwmux))) {
auto &sig_y = cell->getPort(ID::Y);
auto &sig_a = cell->getPort(ID::A);
auto &sig_b = cell->getPort(ID::B);
auto &sig_s = cell->getPort(ID::S);
for (int i = 0; i < GetSize(sig_y); i++)
if (maybe_x(sig_a[i]) || maybe_x(sig_b[i]) || maybe_x(sig_s[i]))
mark_maybe_x(sig_y[i]);
return;
}
if (cell->type.in(ID($_MUX_), ID($mux), ID($bmux))) {
auto &sig_y = cell->getPort(ID::Y);
auto &sig_a = cell->getPort(ID::A);
auto &sig_b = cell->getPort(ID::B);
auto &sig_s = cell->getPort(ID::S);
if (maybe_x(sig_s)) {
mark_maybe_x(sig_y);
return;
}
for (int i = 0; i < GetSize(sig_y); i++) {
if (maybe_x(sig_a[i])) {
mark_maybe_x(sig_y[i]);
continue;
}
for (int j = i; j < GetSize(sig_b); j += GetSize(sig_y)) {
if (maybe_x(sig_b[j])) {
mark_maybe_x(sig_y[i]);
break;
}
}
}
return;
}
if (cell->type.in(ID($demux))) {
auto &sig_y = cell->getPort(ID::Y);
auto &sig_a = cell->getPort(ID::A);
auto &sig_s = cell->getPort(ID::S);
if (maybe_x(sig_s)) {
mark_maybe_x(sig_y);
return;
}
for (int i = 0; i < GetSize(sig_a); i++)
if (maybe_x(sig_a[i]))
for (int j = i; j < GetSize(sig_y); j += GetSize(sig_a))
mark_maybe_x(sig_y[j]);
return;
}
if (cell->type.in(ID($shl), ID($shr), ID($sshl), ID($sshr), ID($shift))) {
auto &sig_b = cell->getPort(ID::B);
auto &sig_y = cell->getPort(ID::Y);
if (maybe_x(sig_b)) {
mark_maybe_x(sig_y);
return;
}
auto &sig_a = cell->getPort(ID::A);
if (maybe_x(sig_a)) {
// We could be more precise for shifts, but that's not required
// for correctness, so let's keep it simple
mark_maybe_x(sig_y);
return;
}
return;
}
if (cell->type.in(ID($shiftx))) {
auto &sig_b = cell->getPort(ID::B);
auto &sig_y = cell->getPort(ID::Y);
if (cell->getParam(ID::B_SIGNED).as_bool() || GetSize(sig_b) >= 30) {
mark_maybe_x(sig_y);
} else {
int max_shift = (1 << GetSize(sig_b)) - 1;
auto &sig_a = cell->getPort(ID::A);
for (int i = 0; i < GetSize(sig_y); i++)
if (i + max_shift >= GetSize(sig_a))
mark_maybe_x(sig_y[i]);
}
if (maybe_x(sig_b)) {
mark_maybe_x(sig_y);
return;
}
auto &sig_a = cell->getPort(ID::A);
if (maybe_x(sig_a)) {
// We could be more precise for shifts, but that's not required
// for correctness, so let's keep it simple
mark_maybe_x(sig_y);
return;
}
return;
}
if (cell->type.in(ID($add), ID($sub), ID($mul), ID($neg))) {
if (inputs_maybe_x(cell))
mark_outputs_maybe_x(cell);
return;
}
if (cell->type.in(ID($div), ID($mod), ID($divfloor), ID($modfloor))) {
mark_outputs_maybe_x(cell);
return;
}
if (cell->type.in(
ID($le), ID($lt), ID($ge), ID($gt),
ID($reduce_and), ID($reduce_or), ID($reduce_xor), ID($reduce_xnor),
ID($reduce_bool), ID($logic_not), ID($logic_or), ID($logic_and),
ID($eq), ID($ne),
ID($_NOT_), ID($_AND_), ID($_NAND_), ID($_ANDNOT_), ID($_OR_), ID($_NOR_), ID($_ORNOT_), ID($_XOR_), ID($_XNOR_)
)) {
auto &sig_y = cell->getPort(ID::Y);
if (inputs_maybe_x(cell))
mark_maybe_x(sig_y[0]);
return;
}
log_warning("Unhandled cell %s (%s) during maybe-x marking\n", log_id(cell), log_id(cell->type));
mark_outputs_maybe_x(cell);
}
void process_cells()
{
for (auto cell : module->selected_cells())
process_cell(cell);
}
void process_cell(Cell *cell)
{
if (!ports_maybe_x(cell)) {
if (cell->type == ID($bweq)) {
auto sig_y = cell->getPort(ID::Y);
auto sig_a = cell->getPort(ID::A);
auto sig_b = cell->getPort(ID::B);
auto name = cell->name;
module->remove(cell);
module->addXnor(name, sig_a, sig_b, sig_y);
return;
}
if (cell->type.in(ID($nex), ID($eqx))) {
auto sig_y = cell->getPort(ID::Y);
auto sig_a = cell->getPort(ID::A);
auto sig_b = cell->getPort(ID::B);
auto name = cell->name;
module->remove(cell);
if (cell->type == ID($eqx))
module->addEq(name, sig_a, sig_b, sig_y);
else
module->addNe(name, sig_a, sig_b, sig_y);
return;
}
return;
}
if (cell->type.in(ID($not), ID($_NOT_))) {
auto &sig_y = cell->getPort(ID::Y);
auto sig_a = cell->getPort(ID::A);
if (cell->type == ID($not))
sig_a.extend_u0(GetSize(sig_y), cell->getParam(ID::A_SIGNED).as_bool());
auto enc_a = encoded(sig_a);
auto enc_y = encoded(sig_y, true);
enc_y.connect_x(enc_a.is_x);
enc_y.connect_0(enc_a.is_1);
enc_y.connect_1(enc_a.is_0);
module->remove(cell);
return;
}
if (cell->type.in(ID($and), ID($or), ID($_AND_), ID($_OR_), ID($_NAND_), ID($_NOR_), ID($_ANDNOT_), ID($_ORNOT_))) {
auto &sig_y = cell->getPort(ID::Y);
auto sig_a = cell->getPort(ID::A);
auto sig_b = cell->getPort(ID::B);
if (cell->type.in(ID($and), ID($or))) {
sig_a.extend_u0(GetSize(sig_y), cell->getParam(ID::A_SIGNED).as_bool());
sig_b.extend_u0(GetSize(sig_y), cell->getParam(ID::B_SIGNED).as_bool());
}
auto enc_a = encoded(sig_a);
auto enc_b = encoded(sig_b);
auto enc_y = encoded(sig_y, true);
if (cell->type.in(ID($or), ID($_OR_)))
enc_a.invert(), enc_b.invert(), enc_y.invert();
if (cell->type.in(ID($_NAND_), ID($_NOR_)))
enc_y.invert();
if (cell->type.in(ID($_ANDNOT_), ID($_ORNOT_)))
enc_b.invert();
enc_y.connect_0(module->Or(NEW_ID, enc_a.is_0, enc_b.is_0));
enc_y.connect_1(module->And(NEW_ID, enc_a.is_1, enc_b.is_1));
enc_y.auto_x();
module->remove(cell);
return;
}
if (cell->type.in(ID($reduce_and), ID($reduce_or), ID($reduce_bool), ID($logic_not))) {
auto &sig_y = cell->getPort(ID::Y);
auto &sig_a = cell->getPort(ID::A);
auto enc_a = encoded(sig_a);
auto enc_y = encoded(sig_y, true);
enc_y.connect_as_bool();
if (cell->type.in(ID($reduce_or), ID($reduce_bool)))
enc_a.invert(), enc_y.invert();
if (cell->type == ID($logic_not))
enc_a.invert();
enc_y.connect_0(module->ReduceOr(NEW_ID, enc_a.is_0));
enc_y.connect_1(module->ReduceAnd(NEW_ID, enc_a.is_1));
enc_y.auto_x();
module->remove(cell);
return;
}
if (cell->type.in(ID($reduce_xor), ID($reduce_xnor))) {
auto &sig_y = cell->getPort(ID::Y);
auto &sig_a = cell->getPort(ID::A);
auto enc_a = encoded(sig_a);
auto enc_y = encoded(sig_y, true);
enc_y.connect_as_bool();
if (cell->type == ID($reduce_xnor))
enc_y.invert();
enc_y.connect_x(module->ReduceOr(NEW_ID, enc_a.is_x));
enc_y.connect_1_under_x(module->ReduceXor(NEW_ID, enc_a.is_1));
enc_y.auto_0();
module->remove(cell);
return;
}
if (cell->type.in(ID($logic_and), ID($logic_or))) {
auto &sig_y = cell->getPort(ID::Y);
auto &sig_a = cell->getPort(ID::A);
auto &sig_b = cell->getPort(ID::B);
auto enc_a = encoded(sig_a);
auto enc_b = encoded(sig_b);
auto enc_y = encoded(sig_y, true);
enc_y.connect_as_bool();
auto a_is_1 = module->ReduceOr(NEW_ID, enc_a.is_1);
auto a_is_0 = module->ReduceAnd(NEW_ID, enc_a.is_0);
auto b_is_1 = module->ReduceOr(NEW_ID, enc_b.is_1);
auto b_is_0 = module->ReduceAnd(NEW_ID, enc_b.is_0);
if (cell->type == ID($logic_or))
enc_y.invert(), std::swap(a_is_0, a_is_1), std::swap(b_is_0, b_is_1);
enc_y.connect_0(module->Or(NEW_ID, a_is_0, b_is_0));
enc_y.connect_1(module->And(NEW_ID, a_is_1, b_is_1));
enc_y.auto_x();
module->remove(cell);
return;
}
if (cell->type.in(ID($xor), ID($xnor), ID($_XOR_), ID($_XNOR_))) {
auto &sig_y = cell->getPort(ID::Y);
auto sig_a = cell->getPort(ID::A);
auto sig_b = cell->getPort(ID::B);
if (cell->type.in(ID($xor), ID($xnor))) {
sig_a.extend_u0(GetSize(sig_y), cell->getParam(ID::A_SIGNED).as_bool());
sig_b.extend_u0(GetSize(sig_y), cell->getParam(ID::B_SIGNED).as_bool());
}
auto enc_a = encoded(sig_a);
auto enc_b = encoded(sig_b);
auto enc_y = encoded(sig_y, true);
if (cell->type.in(ID($xnor), ID($_XNOR_)))
enc_y.invert();
enc_y.connect_x(module->Or(NEW_ID, enc_a.is_x, enc_b.is_x));
enc_y.connect_1_under_x(module->Xor(NEW_ID, enc_a.is_1, enc_b.is_1));
enc_y.auto_0();
module->remove(cell);
return;
}
if (cell->type.in(ID($eq), ID($ne))) {
auto &sig_y = cell->getPort(ID::Y);
auto sig_a = cell->getPort(ID::A);
auto sig_b = cell->getPort(ID::B);
int width = std::max(GetSize(sig_a), GetSize(sig_b));
sig_a.extend_u0(width, cell->getParam(ID::A_SIGNED).as_bool());
sig_b.extend_u0(width, cell->getParam(ID::B_SIGNED).as_bool());
auto enc_a = encoded(sig_a);
auto enc_b = encoded(sig_b);
auto enc_y = encoded(sig_y, true);
enc_y.connect_as_bool();
if (cell->type == ID($ne))
enc_y.invert();
auto delta = module->Xor(NEW_ID, enc_a.is_1, enc_b.is_1);
auto xpos = module->Or(NEW_ID, enc_a.is_x, enc_b.is_x);
enc_y.connect_0(module->ReduceOr(NEW_ID, module->And(NEW_ID, delta, module->Not(NEW_ID, xpos))));
enc_y.connect_x_under_0(module->ReduceOr(NEW_ID, xpos));
enc_y.auto_1();
module->remove(cell);
return;
}
if (cell->type.in(ID($eqx), ID($nex))) {
auto &sig_y = cell->getPort(ID::Y);
auto sig_a = cell->getPort(ID::A);
auto sig_b = cell->getPort(ID::B);
int width = std::max(GetSize(sig_a), GetSize(sig_b));
sig_a.extend_u0(width, cell->getParam(ID::A_SIGNED).as_bool());
sig_b.extend_u0(width, cell->getParam(ID::B_SIGNED).as_bool());
auto enc_a = encoded(sig_a);
auto enc_b = encoded(sig_b);
auto delta_0 = module->Xnor(NEW_ID, enc_a.is_0, enc_b.is_0);
auto delta_1 = module->Xnor(NEW_ID, enc_a.is_1, enc_b.is_1);
auto eq = module->ReduceAnd(NEW_ID, {delta_0, delta_1});
auto res = cell->type == ID($nex) ? module->Not(NEW_ID, eq) : eq;
module->connect(sig_y[0], res);
if (GetSize(sig_y) > 1)
module->connect(sig_y.extract(1, GetSize(sig_y) - 1), Const(State::S0, GetSize(sig_y) - 1));
module->remove(cell);
return;
}
if (cell->type.in(ID($bweqx))) {
auto &sig_y = cell->getPort(ID::Y);
auto &sig_a = cell->getPort(ID::A);
auto &sig_b = cell->getPort(ID::B);
auto enc_a = encoded(sig_a);
auto enc_b = encoded(sig_b);
auto delta_0 = module->Xnor(NEW_ID, enc_a.is_0, enc_b.is_0);
auto delta_1 = module->Xnor(NEW_ID, enc_a.is_1, enc_b.is_1);
module->addAnd(NEW_ID, delta_0, delta_1, sig_y);
module->remove(cell);
return;
}
if (cell->type.in(ID($_MUX_), ID($mux), ID($bwmux))) {
auto &sig_y = cell->getPort(ID::Y);
auto &sig_a = cell->getPort(ID::A);
auto &sig_b = cell->getPort(ID::B);
auto sig_s = cell->getPort(ID::S);
if (cell->type == ID($mux))
sig_s = SigSpec(sig_s[0], GetSize(sig_y));
auto enc_a = encoded(sig_a);
auto enc_b = encoded(sig_b);
auto enc_s = encoded(sig_s);
auto enc_y = encoded(sig_y, true);
enc_y.connect_1(module->And(NEW_ID,
module->Or(NEW_ID, enc_a.is_1, enc_s.is_1),
module->Or(NEW_ID, enc_b.is_1, enc_s.is_0)));
enc_y.connect_0(module->And(NEW_ID,
module->Or(NEW_ID, enc_a.is_0, enc_s.is_1),
module->Or(NEW_ID, enc_b.is_0, enc_s.is_0)));
enc_y.auto_x();
module->remove(cell);
return;
}
if (cell->type.in(ID($pmux))) {
auto &sig_y = cell->getPort(ID::Y);
auto &sig_a = cell->getPort(ID::A);
auto &sig_b = cell->getPort(ID::B);
auto &sig_s = cell->getPort(ID::S);
auto enc_a = encoded(sig_a);
auto enc_b = encoded(sig_b);
auto enc_s = encoded(sig_s);
auto enc_y = encoded(sig_y, true);
int width = GetSize(enc_y);
auto all_x = module->ReduceOr(NEW_ID, {
enc_s.is_x,
module->And(NEW_ID, enc_s.is_1, module->Sub(NEW_ID, enc_s.is_1, Const(1, width)))
});
auto selected = enc_a;
for (int i = 0; i < GetSize(enc_s); i++) {
auto sel_bit = enc_s.is_1[i];
selected.is_0 = module->Mux(NEW_ID, selected.is_0, enc_b.is_0.extract(i * width, width), sel_bit);
selected.is_1 = module->Mux(NEW_ID, selected.is_1, enc_b.is_1.extract(i * width, width), sel_bit);
selected.is_x = module->Mux(NEW_ID, selected.is_x, enc_b.is_x.extract(i * width, width), sel_bit);
}
enc_y.connect_0(module->Mux(NEW_ID, selected.is_0, Const(State::S0, width), all_x));
enc_y.connect_1(module->Mux(NEW_ID, selected.is_1, Const(State::S0, width), all_x));
enc_y.connect_x(module->Mux(NEW_ID, selected.is_x, Const(State::S1, width), all_x));
module->remove(cell);
return;
}
if (cell->type.in(ID($shl), ID($shr), ID($sshl), ID($sshr), ID($shift), ID($shiftx))) {
auto &sig_y = cell->getPort(ID::Y);
auto &sig_a = cell->getPort(ID::A);
auto &sig_b = cell->getPort(ID::B);
auto enc_a = encoded(sig_a);
auto enc_b = encoded(sig_b);
auto enc_y = encoded(sig_y, true);
auto all_x = module->ReduceOr(NEW_ID, enc_b.is_x)[0];
auto not_all_x = module->Not(NEW_ID, all_x)[0];
SigSpec y_not_0 = module->addWire(NEW_ID, GetSize(sig_y));
SigSpec y_1 = module->addWire(NEW_ID, GetSize(sig_y));
SigSpec y_x = module->addWire(NEW_ID, GetSize(sig_y));
auto encoded_type = cell->type == ID($shiftx) ? ID($shift) : cell->type;
if (cell->type == ID($shiftx)) {
std::swap(enc_a.is_0, enc_a.is_x);
}
auto shift_0 = module->addCell(NEW_ID, encoded_type);
shift_0->parameters = cell->parameters;
shift_0->setPort(ID::A, module->Not(NEW_ID, enc_a.is_0));
shift_0->setPort(ID::B, enc_b.is_1);
shift_0->setPort(ID::Y, y_not_0);
auto shift_1 = module->addCell(NEW_ID, encoded_type);
shift_1->parameters = cell->parameters;
shift_1->setPort(ID::A, enc_a.is_1);
shift_1->setPort(ID::B, enc_b.is_1);
shift_1->setPort(ID::Y, y_1);
auto shift_x = module->addCell(NEW_ID, encoded_type);
shift_x->parameters = cell->parameters;
shift_x->setPort(ID::A, enc_a.is_x);
shift_x->setPort(ID::B, enc_b.is_1);
shift_x->setPort(ID::Y, y_x);
SigSpec y_0 = module->Not(NEW_ID, y_not_0);
if (cell->type == ID($shiftx))
std::swap(y_0, y_x);
enc_y.connect_0(module->And(NEW_ID, y_0, SigSpec(not_all_x, GetSize(sig_y))));
enc_y.connect_1(module->And(NEW_ID, y_1, SigSpec(not_all_x, GetSize(sig_y))));
enc_y.connect_x(module->Or(NEW_ID, y_x, SigSpec(all_x, GetSize(sig_y))));
module->remove(cell);
return;
}
if (cell->type.in(ID($ff))) {
auto &sig_d = cell->getPort(ID::D);
auto &sig_q = cell->getPort(ID::Q);
auto init_q = initvals(sig_q);
auto init_q_is_1 = init_q;
auto init_q_is_x = init_q;
for (auto &bit : init_q_is_1)
bit = bit == State::S1 ? State::S1 : State::S0;
for (auto &bit : init_q_is_x)
bit = bit == State::Sx ? State::S1 : State::S0;
initvals.remove_init(sig_q);
auto enc_d = encoded(sig_d);
auto enc_q = encoded(sig_q, true);
auto data_q = module->addWire(NEW_ID, GetSize(sig_q));
module->addFf(NEW_ID, enc_d.is_1, data_q);
module->addFf(NEW_ID, enc_d.is_x, enc_q.is_x);
initvals.set_init(data_q, init_q_is_1);
initvals.set_init(enc_q.is_x, init_q_is_x);
enc_q.connect_1_under_x(data_q);
enc_q.auto_0();
module->remove(cell);
return;
}
if (RTLIL::builtin_ff_cell_types().count(cell->type) || cell->type == ID($anyinit)) {
FfData ff(&initvals, cell);
if ((ff.has_clk || ff.has_gclk) && !ff.has_ce && !ff.has_aload && !ff.has_srst && !ff.has_arst && !ff.has_sr) {
if (ff.has_clk && maybe_x(ff.sig_clk)) {
log_warning("Only non-x CLK inputs are currently supported for %s (%s)\n", log_id(cell), log_id(cell->type));
} else {
auto init_q = ff.val_init;
auto init_q_is_1 = init_q;
auto init_q_is_x = init_q;
if (ff.is_anyinit) {
for (auto &bit : init_q_is_1)
bit = State::Sx;
for (auto &bit : init_q_is_x)
bit = State::S0;
} else {
for (auto &bit : init_q_is_1)
bit = bit == State::S1 ? State::S1 : State::S0;
for (auto &bit : init_q_is_x)
bit = bit == State::Sx ? State::S1 : State::S0;
}
ff.remove();
auto enc_d = encoded(ff.sig_d);
auto enc_q = encoded(ff.sig_q, true);
auto data_q = module->addWire(NEW_ID, GetSize(ff.sig_q));
ff.sig_d = enc_d.is_1;
ff.sig_q = data_q;
ff.val_init = init_q_is_1;
ff.emit();
ff.name = NEW_ID;
ff.cell = nullptr;
ff.sig_d = enc_d.is_x;
ff.sig_q = enc_q.is_x;
ff.is_anyinit = false;
ff.val_init = init_q_is_x;
ff.emit();
enc_q.connect_1_under_x(data_q);
enc_q.auto_0();
return;
}
} else {
log_warning("Unhandled FF-cell %s (%s), consider running clk2fflogic, async2sync and/or dffunmap\n", log_id(cell), log_id(cell->type));
}
}
// Celltypes where any input x bit makes the whole output x
if (cell->type.in(
ID($neg),
ID($le), ID($lt), ID($ge), ID($gt),
ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($divfloor), ID($modfloor)
)) {
SigSpec inbits_x;
for (auto &conn : cell->connections()) {
if (cell->input(conn.first)) {
auto enc_port = encoded(conn.second);
inbits_x.append(enc_port.is_x);
cell->setPort(conn.first, enc_port.is_1);
}
}
if (cell->type.in(ID($div), ID($mod), ID($divfloor), ID($modfloor))) {
auto sig_b = cell->getPort(ID::B);
auto invalid = module->LogicNot(NEW_ID, sig_b);
inbits_x.append(invalid);
sig_b[0] = module->Or(NEW_ID, sig_b[0], invalid);
cell->setPort(ID::B, sig_b);
}
SigBit outbits_x = (GetSize(inbits_x) == 1 ? inbits_x : module->ReduceOr(NEW_ID, inbits_x));
bool bool_out = cell->type.in(ID($le), ID($lt), ID($ge), ID($gt));
for (auto &conn : cell->connections()) {
if (cell->output(conn.first)) {
auto enc_port = encoded(conn.second, true);
if (bool_out)
enc_port.connect_as_bool();
SigSpec new_output = module->addWire(NEW_ID, GetSize(conn.second));
enc_port.connect_1_under_x(bool_out ? new_output.extract(0) : new_output);
enc_port.connect_x(SigSpec(outbits_x, GetSize(enc_port)));
enc_port.auto_0();
cell->setPort(conn.first, new_output);
}
}
return;
}
if (cell->type == ID($bmux)) // TODO might want to support bmux natively anyway
log("Running 'bmuxmap' preserves x-propagation and can be run before 'xprop'.\n");
if (cell->type == ID($demux)) // TODO might want to support demux natively anyway
log("Running 'demuxmap' preserves x-propagation and can be run before 'xprop'.\n");
if (options.required)
log_error("Unhandled cell %s (%s)\n", log_id(cell), log_id(cell->type));
else
log_warning("Unhandled cell %s (%s)\n", log_id(cell), log_id(cell->type));
}
void split_ports()
{
if (!options.split_inputs && !options.split_outputs)
return;
int port_id = 1;
for (auto port : module->ports) {
auto wire = module->wire(port);
if (module->design->selected(module, wire)) {
if (wire->port_input == wire->port_output) {
log_warning("Port %s not an input or an output port which is not supported by xprop\n", log_id(wire));
} else if ((options.split_inputs && !options.assume_def_inputs && wire->port_input) || (options.split_outputs && wire->port_output)) {
auto port_d = module->uniquify(stringf("%s_d", port.c_str()));
auto port_x = module->uniquify(stringf("%s_x", port.c_str()));
auto wire_d = module->addWire(port_d, GetSize(wire));
auto wire_x = module->addWire(port_x, GetSize(wire));
wire_d->port_input = wire->port_input;
wire_d->port_output = wire->port_output;
wire_d->port_id = port_id++;
wire_x->port_input = wire->port_input;
wire_x->port_output = wire->port_output;
wire_x->port_id = port_id++;
if (wire->port_output) {
auto enc = encoded(wire);
module->connect(wire_d, enc.is_1);
module->connect(wire_x, enc.is_x);
if (options.split_public) {
// Need to hide the original wire so split_public doesn't try to split it again
module->rename(wire, NEW_ID_SUFFIX(wire->name.c_str()));
}
} else {
auto enc = encoded(wire, true);
enc.connect_x(wire_x);
enc.connect_1_under_x(wire_d);
enc.auto_0();
}
wire->port_input = wire->port_output = false;
wire->port_id = 0;
continue;
}
}
wire->port_id = port_id++;
}
module->fixup_ports();
}
void split_public()
{
if (!options.split_public)
return;
for (auto wire : module->selected_wires()) {
if (wire->port_input || wire->port_output || !wire->name.isPublic())
continue;
auto name_d = module->uniquify(stringf("%s_d", wire->name.c_str()));
auto name_x = module->uniquify(stringf("%s_x", wire->name.c_str()));
auto wire_d = module->addWire(name_d, GetSize(wire));
auto wire_x = module->addWire(name_x, GetSize(wire));
auto enc = encoded(wire);
module->connect(wire_d, enc.is_1);
module->connect(wire_x, enc.is_x);
module->rename(wire, NEW_ID_SUFFIX(wire->name.c_str()));
}
}
void encode_remaining()
{
pool<Wire *> enc_undriven_wires;
for (auto &enc_bit : encoded_bits) {
if (!enc_bit.second.driven) {
log_assert(enc_bit.first.is_wire());
enc_undriven_wires.insert(enc_bit.first.wire);
}
}
if (options.formal && !enc_undriven_wires.empty()) {
for (auto &bit : enc_undriven_wires)
log_warning("Found encoded wire %s having a non-encoded driver\n", log_signal(bit));
log_error("Found encoded wires having a non-encoded driver, not allowed in -formal mode\n");
}
for (auto wire : enc_undriven_wires) {
SigSpec sig(sigmap(wire));
SigSpec orig;
EncodedSig enc;
for (auto bit : sig) {
auto it = encoded_bits.find(bit);
if (it == encoded_bits.end() || it->second.driven)
continue;
orig.append(bit);
enc.is_0.append(it->second.is_0);
enc.is_1.append(it->second.is_1);
enc.is_x.append(it->second.is_x);
it->second.driven = true;
}
module->addBweqx(NEW_ID, orig, Const(State::S0, GetSize(orig)), enc.is_0);
module->addBweqx(NEW_ID, orig, Const(State::S1, GetSize(orig)), enc.is_1);
module->addBweqx(NEW_ID, orig, Const(State::Sx, GetSize(orig)), enc.is_x);
}
}
};
struct XpropPass : public Pass {
XpropPass() : Pass("xprop", "formal x propagation") {}
void help() override
{
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
log("\n");
log(" xprop [options] [selection]\n");
log("\n");
log("This pass transforms the circuit into an equivalent circuit that explicitly\n");
log("encodes the propagation of x values using purely 2-valued logic. On the\n");
log("interface between xprop-transformed and non-transformed parts of the design,\n");
log("appropriate conversions are inserted automatically.\n");
log("\n");
log(" -split-inputs\n");
log(" -split-outputs\n");
log(" -split-ports\n");
log(" Replace each input/output/port with two new ports, one carrying the\n");
log(" defined values (named <portname>_d) and one carrying the mask of which\n");
log(" bits are x (named <portname>_x). When a bit in the <portname>_x is set\n");
log(" the corresponding bit in <portname>_d is ignored for inputs and\n");
log(" guaranteed to be 0 for outputs.\n");
log("\n");
log(" -split-public\n");
log(" Replace each public non-port wire with two new wires, one carrying the\n");
log(" defined values (named <wirename>_d) and one carrying the mask of which\n");
log(" bits are x (named <wirename>_x). When a bit in the <portname>_x is set\n");
log(" the corresponding bit in <wirename>_d is guaranteed to be 0 for\n");
log(" outputs.\n");
log("\n");
log(" -assume-encoding\n");
log(" Add encoding invariants as assumptions. This can speed up formal\n");
log(" verification tasks.\n");
log("\n");
log(" -assert-encoding\n");
log(" Add encoding invariants as assertions. Used for testing the xprop\n");
log(" pass itself.\n");
log("\n");
log(" -assume-def-inputs\n");
log(" Assume all inputs are fully defined. This adds corresponding\n");
log(" assumptions to the design and uses these assumptions to optimize the\n");
log(" xprop encoding.\n");
log("\n");
log(" -required\n");
log(" Produce a runtime error if any encountered cell could not be encoded.\n");
log("\n");
log(" -formal\n");
log(" Produce a runtime error if any encoded cell uses a signal that is\n");
log(" neither known to be non-x nor driven by another encoded cell.\n");
log("\n");
log(" -debug-asserts\n");
log(" Add assertions checking that the encoding used by this pass never\n");
log(" produces x values within the encoded signals.\n");
log("\n");
}
void execute(std::vector<std::string> args, RTLIL::Design *design) override
{
XpropOptions options;
log_header(design, "Executing XPROP pass.\n");
size_t argidx;
for (argidx = 1; argidx < args.size(); argidx++) {
if (args[argidx] == "-split-ports") {
options.split_inputs = true;
options.split_outputs = true;
continue;
}
if (args[argidx] == "-split-inputs") {
options.split_inputs = true;
continue;
}
if (args[argidx] == "-split-outputs") {
options.split_outputs = true;
continue;
}
if (args[argidx] == "-split-public") {
options.split_public = true;
continue;
}
if (args[argidx] == "-assume-encoding") {
options.assume_encoding = true;
continue;
}
if (args[argidx] == "-assert-encoding") {
options.assert_encoding = true;
continue;
}
if (args[argidx] == "-assume-def-inputs") {
options.assume_def_inputs = true;
continue;
}
if (args[argidx] == "-required") {
options.required = true; // TODO check more
continue;
}
if (args[argidx] == "-formal") {
options.formal = true;
options.required = true;
continue;
}
if (args[argidx] == "-debug-asserts") { // TODO documented
options.debug_asserts = true;
options.assert_encoding = true;
continue;
}
break;
}
if (options.assert_encoding && options.assume_encoding)
log_cmd_error("The options -assert-encoding and -assume-encoding are exclusive.\n");
extra_args(args, argidx, design);
log_push();
Pass::call(design, "bmuxmap");
Pass::call(design, "demuxmap");
log_pop();
for (auto module : design->selected_modules()) {
if (options.assume_def_inputs) {
for (auto port : module->ports) {
auto wire = module->wire(port);
if (!module->design->selected(module, wire))
continue;
if (wire->port_input) {
module->addAssume(NEW_ID, module->Not(NEW_ID, module->ReduceOr(NEW_ID, module->Bweqx(NEW_ID, wire, Const(State::Sx, GetSize(wire))))), State::S1);
}
}
}
XpropWorker worker(module, options);
log_debug("Marking all x-bits.\n");
worker.mark_all_maybe_x();
log_debug("Repalcing cells.\n");
worker.process_cells();
log_debug("Splitting ports.\n");
worker.split_ports();
log_debug("Splitting public signals.\n");
worker.split_public();
log_debug("Encode remaining signals.\n");
worker.encode_remaining();
}
}
} XpropPass;
PRIVATE_NAMESPACE_END
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