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yosys/passes/opt/opt_const.cc

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/*
* yosys -- Yosys Open SYnthesis Suite
*
* Copyright (C) 2012 Clifford Wolf <clifford@clifford.at>
*
* 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/register.h"
#include "kernel/sigtools.h"
#include "kernel/celltypes.h"
#include "kernel/utils.h"
#include "kernel/log.h"
#include <stdlib.h>
#include <stdio.h>
#include <algorithm>
static bool did_something;
static void replace_undriven(RTLIL::Design *design, RTLIL::Module *module)
{
CellTypes ct(design);
SigMap sigmap(module);
SigPool driven_signals;
SigPool used_signals;
SigPool all_signals;
for (auto cell : module->cells())
for (auto &conn : cell->connections()) {
if (!ct.cell_known(cell->type) || ct.cell_output(cell->type, conn.first))
driven_signals.add(sigmap(conn.second));
if (!ct.cell_known(cell->type) || ct.cell_input(cell->type, conn.first))
used_signals.add(sigmap(conn.second));
}
for (auto wire : module->wires()) {
if (wire->port_input)
driven_signals.add(sigmap(wire));
if (wire->port_output)
used_signals.add(sigmap(wire));
all_signals.add(sigmap(wire));
}
all_signals.del(driven_signals);
RTLIL::SigSpec undriven_signals = all_signals.export_all();
for (auto &c : undriven_signals.chunks())
{
RTLIL::SigSpec sig = c;
if (c.wire->name[0] == '$')
sig = used_signals.extract(sig);
if (sig.size() == 0)
continue;
log("Setting undriven signal in %s to undef: %s\n", RTLIL::id2cstr(module->name), log_signal(c));
module->connect(RTLIL::SigSig(c, RTLIL::SigSpec(RTLIL::State::Sx, c.width)));
did_something = true;
}
}
static void replace_cell(SigMap &assign_map, RTLIL::Module *module, RTLIL::Cell *cell, std::string info, std::string out_port, RTLIL::SigSpec out_val)
{
RTLIL::SigSpec Y = cell->getPort(out_port);
out_val.extend_u0(Y.size(), false);
log("Replacing %s cell `%s' (%s) in module `%s' with constant driver `%s = %s'.\n",
cell->type.c_str(), cell->name.c_str(), info.c_str(),
module->name.c_str(), log_signal(Y), log_signal(out_val));
// log_cell(cell);
assign_map.add(Y, out_val);
module->connect(Y, out_val);
module->remove(cell);
did_something = true;
}
static bool group_cell_inputs(RTLIL::Module *module, RTLIL::Cell *cell, bool commutative, bool extend_u0, SigMap &sigmap)
{
std::string b_name = cell->hasPort("\\B") ? "\\B" : "\\A";
bool a_signed = cell->parameters.at("\\A_SIGNED").as_bool();
bool b_signed = cell->parameters.at(b_name + "_SIGNED").as_bool();
RTLIL::SigSpec sig_a = sigmap(cell->getPort("\\A"));
RTLIL::SigSpec sig_b = sigmap(cell->getPort(b_name));
RTLIL::SigSpec sig_y = sigmap(cell->getPort("\\Y"));
if (extend_u0) {
sig_a.extend_u0(sig_y.size(), a_signed);
sig_b.extend_u0(sig_y.size(), b_signed);
} else {
sig_a.extend(sig_y.size(), a_signed);
sig_b.extend(sig_y.size(), b_signed);
}
std::vector<RTLIL::SigBit> bits_a = sig_a, bits_b = sig_b, bits_y = sig_y;
enum { GRP_DYN, GRP_CONST_A, GRP_CONST_B, GRP_CONST_AB, GRP_N };
std::map<std::pair<RTLIL::SigBit, RTLIL::SigBit>, std::set<RTLIL::SigBit>> grouped_bits[GRP_N];
for (int i = 0; i < SIZE(bits_y); i++)
{
int group_idx = GRP_DYN;
RTLIL::SigBit bit_a = bits_a[i], bit_b = bits_b[i];
if (cell->type == "$or" && (bit_a == RTLIL::State::S1 || bit_b == RTLIL::State::S1))
bit_a = bit_b = RTLIL::State::S1;
if (cell->type == "$and" && (bit_a == RTLIL::State::S0 || bit_b == RTLIL::State::S0))
bit_a = bit_b = RTLIL::State::S0;
if (bit_a.wire == NULL && bit_b.wire == NULL)
group_idx = GRP_CONST_AB;
else if (bit_a.wire == NULL)
group_idx = GRP_CONST_A;
else if (bit_b.wire == NULL && commutative)
group_idx = GRP_CONST_A, std::swap(bit_a, bit_b);
else if (bit_b.wire == NULL)
group_idx = GRP_CONST_B;
grouped_bits[group_idx][std::pair<RTLIL::SigBit, RTLIL::SigBit>(bit_a, bit_b)].insert(bits_y[i]);
}
for (int i = 0; i < GRP_N; i++)
if (SIZE(grouped_bits[i]) == SIZE(bits_y))
return false;
log("Replacing %s cell `%s' in module `%s' with cells using grouped bits:\n",
log_id(cell->type), log_id(cell), log_id(module));
for (int i = 0; i < GRP_N; i++)
{
if (grouped_bits[i].empty())
continue;
RTLIL::Wire *new_y = module->addWire(NEW_ID, SIZE(grouped_bits[i]));
RTLIL::SigSpec new_a, new_b;
RTLIL::SigSig new_conn;
for (auto &it : grouped_bits[i]) {
for (auto &bit : it.second) {
new_conn.first.append_bit(bit);
new_conn.second.append_bit(RTLIL::SigBit(new_y, new_a.size()));
}
new_a.append_bit(it.first.first);
new_b.append_bit(it.first.second);
}
RTLIL::Cell *c = module->addCell(NEW_ID, cell->type);
c->setPort("\\A", new_a);
c->parameters["\\A_WIDTH"] = new_a.size();
c->parameters["\\A_SIGNED"] = false;
if (b_name == "\\B") {
c->setPort("\\B", new_b);
c->parameters["\\B_WIDTH"] = new_b.size();
c->parameters["\\B_SIGNED"] = false;
}
c->setPort("\\Y", new_y);
c->parameters["\\Y_WIDTH"] = new_y->width;
c->check();
module->connect(new_conn);
log(" New cell `%s': A=%s", log_id(c), log_signal(new_a));
if (b_name == "\\B")
log(", B=%s", log_signal(new_b));
log("\n");
}
cover_list("opt.opt_const.fine.group", "$not", "$pos", "$and", "$or", "$xor", "$xnor", cell->type.str());
module->remove(cell);
did_something = true;
return true;
}
static void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool consume_x, bool mux_undef, bool mux_bool, bool do_fine, bool keepdc)
{
if (!design->selected(module))
return;
CellTypes ct_combinational;
ct_combinational.setup_internals();
ct_combinational.setup_stdcells();
SigMap assign_map(module);
std::map<RTLIL::SigSpec, RTLIL::SigSpec> invert_map;
TopoSort<RTLIL::Cell*> cells;
std::map<RTLIL::Cell*, std::set<RTLIL::SigBit>> cell_to_inbit;
std::map<RTLIL::SigBit, std::set<RTLIL::Cell*>> outbit_to_cell;
for (auto cell : module->cells())
if (design->selected(module, cell) && cell->type[0] == '$') {
if ((cell->type == "$_NOT_" || cell->type == "$not" || cell->type == "$logic_not") &&
cell->getPort("\\A").size() == 1 && cell->getPort("\\Y").size() == 1)
invert_map[assign_map(cell->getPort("\\Y"))] = assign_map(cell->getPort("\\A"));
if (ct_combinational.cell_known(cell->type))
for (auto &conn : cell->connections()) {
RTLIL::SigSpec sig = assign_map(conn.second);
sig.remove_const();
if (ct_combinational.cell_input(cell->type, conn.first))
cell_to_inbit[cell].insert(sig.begin(), sig.end());
if (ct_combinational.cell_output(cell->type, conn.first))
for (auto &bit : sig)
outbit_to_cell[bit].insert(cell);
}
cells.node(cell);
}
for (auto &it_right : cell_to_inbit)
for (auto &it_sigbit : it_right.second)
for (auto &it_left : outbit_to_cell[it_sigbit])
cells.edge(it_left, it_right.first);
cells.sort();
for (auto cell : cells.sorted)
{
#define ACTION_DO(_p_, _s_) do { cover("opt.opt_const.action_" S__LINE__); replace_cell(assign_map, module, cell, input.as_string(), _p_, _s_); goto next_cell; } while (0)
#define ACTION_DO_Y(_v_) ACTION_DO("\\Y", RTLIL::SigSpec(RTLIL::State::S ## _v_))
if (do_fine)
{
if (cell->type == "$not" || cell->type == "$pos" ||
cell->type == "$and" || cell->type == "$or" || cell->type == "$xor" || cell->type == "$xnor")
if (group_cell_inputs(module, cell, true, cell->type != "$pos", assign_map))
goto next_cell;
if (cell->type == "$reduce_and")
{
RTLIL::SigSpec sig_a = assign_map(cell->getPort("\\A"));
RTLIL::State new_a = RTLIL::State::S1;
for (auto &bit : sig_a.to_sigbit_vector())
if (bit == RTLIL::State::Sx) {
if (new_a == RTLIL::State::S1)
new_a = RTLIL::State::Sx;
} else if (bit == RTLIL::State::S0) {
new_a = RTLIL::State::S0;
break;
} else if (bit.wire != NULL) {
new_a = RTLIL::State::Sm;
}
if (new_a != RTLIL::State::Sm && RTLIL::SigSpec(new_a) != sig_a) {
cover("opt.opt_const.fine.$reduce_and");
log("Replacing port A of %s cell `%s' in module `%s' with constant driver: %s -> %s\n",
cell->type.c_str(), cell->name.c_str(), module->name.c_str(), log_signal(sig_a), log_signal(new_a));
cell->setPort("\\A", sig_a = new_a);
cell->parameters.at("\\A_WIDTH") = 1;
did_something = true;
}
}
if (cell->type == "$logic_not" || cell->type == "$logic_and" || cell->type == "$logic_or" || cell->type == "$reduce_or" || cell->type == "$reduce_bool")
{
RTLIL::SigSpec sig_a = assign_map(cell->getPort("\\A"));
RTLIL::State new_a = RTLIL::State::S0;
for (auto &bit : sig_a.to_sigbit_vector())
if (bit == RTLIL::State::Sx) {
if (new_a == RTLIL::State::S0)
new_a = RTLIL::State::Sx;
} else if (bit == RTLIL::State::S1) {
new_a = RTLIL::State::S1;
break;
} else if (bit.wire != NULL) {
new_a = RTLIL::State::Sm;
}
if (new_a != RTLIL::State::Sm && RTLIL::SigSpec(new_a) != sig_a) {
cover_list("opt.opt_const.fine.A", "$logic_not", "$logic_and", "$logic_or", "$reduce_or", "$reduce_bool", cell->type.str());
log("Replacing port A of %s cell `%s' in module `%s' with constant driver: %s -> %s\n",
cell->type.c_str(), cell->name.c_str(), module->name.c_str(), log_signal(sig_a), log_signal(new_a));
cell->setPort("\\A", sig_a = new_a);
cell->parameters.at("\\A_WIDTH") = 1;
did_something = true;
}
}
if (cell->type == "$logic_and" || cell->type == "$logic_or")
{
RTLIL::SigSpec sig_b = assign_map(cell->getPort("\\B"));
RTLIL::State new_b = RTLIL::State::S0;
for (auto &bit : sig_b.to_sigbit_vector())
if (bit == RTLIL::State::Sx) {
if (new_b == RTLIL::State::S0)
new_b = RTLIL::State::Sx;
} else if (bit == RTLIL::State::S1) {
new_b = RTLIL::State::S1;
break;
} else if (bit.wire != NULL) {
new_b = RTLIL::State::Sm;
}
if (new_b != RTLIL::State::Sm && RTLIL::SigSpec(new_b) != sig_b) {
cover_list("opt.opt_const.fine.B", "$logic_and", "$logic_or", cell->type.str());
log("Replacing port B of %s cell `%s' in module `%s' with constant driver: %s -> %s\n",
cell->type.c_str(), cell->name.c_str(), module->name.c_str(), log_signal(sig_b), log_signal(new_b));
cell->setPort("\\B", sig_b = new_b);
cell->parameters.at("\\B_WIDTH") = 1;
did_something = true;
}
}
}
if (cell->type == "$logic_or" && (assign_map(cell->getPort("\\A")) == RTLIL::State::S1 || assign_map(cell->getPort("\\B")) == RTLIL::State::S1)) {
cover("opt.opt_const.one_high");
replace_cell(assign_map, module, cell, "one high", "\\Y", RTLIL::State::S1);
goto next_cell;
}
if (cell->type == "$logic_and" && (assign_map(cell->getPort("\\A")) == RTLIL::State::S0 || assign_map(cell->getPort("\\B")) == RTLIL::State::S0)) {
cover("opt.opt_const.one_low");
replace_cell(assign_map, module, cell, "one low", "\\Y", RTLIL::State::S0);
goto next_cell;
}
if (cell->type == "$reduce_xor" || cell->type == "$reduce_xnor" || cell->type == "$shift" || cell->type == "$shiftx" ||
cell->type == "$shl" || cell->type == "$shr" || cell->type == "$sshl" || cell->type == "$sshr" ||
cell->type == "$lt" || cell->type == "$le" || cell->type == "$ge" || cell->type == "$gt" ||
cell->type == "$neg" || cell->type == "$add" || cell->type == "$sub" ||
cell->type == "$mul" || cell->type == "$div" || cell->type == "$mod" || cell->type == "$pow")
{
RTLIL::SigSpec sig_a = assign_map(cell->getPort("\\A"));
RTLIL::SigSpec sig_b = cell->hasPort("\\B") ? assign_map(cell->getPort("\\B")) : RTLIL::SigSpec();
if (cell->type == "$shl" || cell->type == "$shr" || cell->type == "$sshl" || cell->type == "$sshr" || cell->type == "$shift" || cell->type == "$shiftx")
sig_a = RTLIL::SigSpec();
for (auto &bit : sig_a.to_sigbit_vector())
if (bit == RTLIL::State::Sx)
goto found_the_x_bit;
for (auto &bit : sig_b.to_sigbit_vector())
if (bit == RTLIL::State::Sx)
goto found_the_x_bit;
if (0) {
found_the_x_bit:
cover_list("opt.opt_const.xbit", "$reduce_xor", "$reduce_xnor", "$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx",
"$lt", "$le", "$ge", "$gt", "$neg", "$add", "$sub", "$mul", "$div", "$mod", "$pow", cell->type.str());
if (cell->type == "$reduce_xor" || cell->type == "$reduce_xnor" ||
cell->type == "$lt" || cell->type == "$le" || cell->type == "$ge" || cell->type == "$gt")
replace_cell(assign_map, module, cell, "x-bit in input", "\\Y", RTLIL::State::Sx);
else
replace_cell(assign_map, module, cell, "x-bit in input", "\\Y", RTLIL::SigSpec(RTLIL::State::Sx, cell->getPort("\\Y").size()));
goto next_cell;
}
}
if ((cell->type == "$_NOT_" || cell->type == "$not" || cell->type == "$logic_not") && cell->getPort("\\Y").size() == 1 &&
invert_map.count(assign_map(cell->getPort("\\A"))) != 0) {
cover_list("opt.opt_const.invert.double", "$_NOT_", "$not", "$logic_not", cell->type.str());
replace_cell(assign_map, module, cell, "double_invert", "\\Y", invert_map.at(assign_map(cell->getPort("\\A"))));
goto next_cell;
}
if ((cell->type == "$_MUX_" || cell->type == "$mux") && invert_map.count(assign_map(cell->getPort("\\S"))) != 0) {
cover_list("opt.opt_const.invert.muxsel", "$_MUX_", "$mux", cell->type.str());
log("Optimizing away select inverter for %s cell `%s' in module `%s'.\n", log_id(cell->type), log_id(cell), log_id(module));
RTLIL::SigSpec tmp = cell->getPort("\\A");
cell->setPort("\\A", cell->getPort("\\B"));
cell->setPort("\\B", tmp);
cell->setPort("\\S", invert_map.at(assign_map(cell->getPort("\\S"))));
did_something = true;
goto next_cell;
}
if (cell->type == "$_NOT_") {
RTLIL::SigSpec input = cell->getPort("\\A");
assign_map.apply(input);
if (input.match("1")) ACTION_DO_Y(0);
if (input.match("0")) ACTION_DO_Y(1);
if (input.match("*")) ACTION_DO_Y(x);
}
if (cell->type == "$_AND_") {
RTLIL::SigSpec input;
input.append(cell->getPort("\\B"));
input.append(cell->getPort("\\A"));
assign_map.apply(input);
if (input.match(" 0")) ACTION_DO_Y(0);
if (input.match("0 ")) ACTION_DO_Y(0);
if (input.match("11")) ACTION_DO_Y(1);
if (input.match("**")) ACTION_DO_Y(x);
if (input.match("1*")) ACTION_DO_Y(x);
if (input.match("*1")) ACTION_DO_Y(x);
if (consume_x) {
if (input.match(" *")) ACTION_DO_Y(0);
if (input.match("* ")) ACTION_DO_Y(0);
}
if (input.match(" 1")) ACTION_DO("\\Y", input.extract(1, 1));
if (input.match("1 ")) ACTION_DO("\\Y", input.extract(0, 1));
}
if (cell->type == "$_OR_") {
RTLIL::SigSpec input;
input.append(cell->getPort("\\B"));
input.append(cell->getPort("\\A"));
assign_map.apply(input);
if (input.match(" 1")) ACTION_DO_Y(1);
if (input.match("1 ")) ACTION_DO_Y(1);
if (input.match("00")) ACTION_DO_Y(0);
if (input.match("**")) ACTION_DO_Y(x);
if (input.match("0*")) ACTION_DO_Y(x);
if (input.match("*0")) ACTION_DO_Y(x);
if (consume_x) {
if (input.match(" *")) ACTION_DO_Y(1);
if (input.match("* ")) ACTION_DO_Y(1);
}
if (input.match(" 0")) ACTION_DO("\\Y", input.extract(1, 1));
if (input.match("0 ")) ACTION_DO("\\Y", input.extract(0, 1));
}
if (cell->type == "$_XOR_") {
RTLIL::SigSpec input;
input.append(cell->getPort("\\B"));
input.append(cell->getPort("\\A"));
assign_map.apply(input);
if (input.match("00")) ACTION_DO_Y(0);
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 (input.match(" 0")) ACTION_DO("\\Y", input.extract(1, 1));
if (input.match("0 ")) ACTION_DO("\\Y", input.extract(0, 1));
}
if (cell->type == "$_MUX_") {
RTLIL::SigSpec input;
input.append(cell->getPort("\\S"));
input.append(cell->getPort("\\B"));
input.append(cell->getPort("\\A"));
assign_map.apply(input);
if (input.extract(2, 1) == input.extract(1, 1))
ACTION_DO("\\Y", input.extract(2, 1));
if (input.match(" 0")) ACTION_DO("\\Y", input.extract(2, 1));
if (input.match(" 1")) ACTION_DO("\\Y", input.extract(1, 1));
if (input.match("01 ")) ACTION_DO("\\Y", input.extract(0, 1));
if (input.match("10 ")) {
cover("opt.opt_const.mux_to_inv");
cell->type = "$_NOT_";
cell->setPort("\\A", input.extract(0, 1));
cell->unsetPort("\\B");
cell->unsetPort("\\S");
goto next_cell;
}
if (input.match("11 ")) ACTION_DO_Y(1);
if (input.match("00 ")) ACTION_DO_Y(0);
if (input.match("** ")) ACTION_DO_Y(x);
if (input.match("01*")) ACTION_DO_Y(x);
if (input.match("10*")) ACTION_DO_Y(x);
if (mux_undef) {
if (input.match("* ")) ACTION_DO("\\Y", input.extract(1, 1));
if (input.match(" * ")) ACTION_DO("\\Y", input.extract(2, 1));
if (input.match(" *")) ACTION_DO("\\Y", input.extract(2, 1));
}
}
if (cell->type == "$eq" || cell->type == "$ne" || cell->type == "$eqx" || cell->type == "$nex")
{
RTLIL::SigSpec a = cell->getPort("\\A");
RTLIL::SigSpec b = cell->getPort("\\B");
if (cell->parameters["\\A_WIDTH"].as_int() != cell->parameters["\\B_WIDTH"].as_int()) {
int width = std::max(cell->parameters["\\A_WIDTH"].as_int(), cell->parameters["\\B_WIDTH"].as_int());
a.extend_u0(width, cell->parameters["\\A_SIGNED"].as_bool() && cell->parameters["\\B_SIGNED"].as_bool());
b.extend_u0(width, cell->parameters["\\A_SIGNED"].as_bool() && cell->parameters["\\B_SIGNED"].as_bool());
}
RTLIL::SigSpec new_a, new_b;
log_assert(SIZE(a) == SIZE(b));
for (int i = 0; i < SIZE(a); i++) {
if (a[i].wire == NULL && b[i].wire == NULL && a[i] != b[i] && a[i].data <= RTLIL::State::S1 && b[i].data <= RTLIL::State::S1) {
cover_list("opt.opt_const.eqneq.isneq", "$eq", "$ne", "$eqx", "$nex", cell->type.str());
RTLIL::SigSpec new_y = RTLIL::SigSpec((cell->type == "$eq" || cell->type == "$eqx") ? RTLIL::State::S0 : RTLIL::State::S1);
new_y.extend(cell->parameters["\\Y_WIDTH"].as_int(), false);
replace_cell(assign_map, module, cell, "isneq", "\\Y", new_y);
goto next_cell;
}
if (a[i] == b[i])
continue;
new_a.append(a[i]);
new_b.append(b[i]);
}
if (new_a.size() == 0) {
cover_list("opt.opt_const.eqneq.empty", "$eq", "$ne", "$eqx", "$nex", cell->type.str());
RTLIL::SigSpec new_y = RTLIL::SigSpec((cell->type == "$eq" || cell->type == "$eqx") ? RTLIL::State::S1 : RTLIL::State::S0);
new_y.extend(cell->parameters["\\Y_WIDTH"].as_int(), false);
replace_cell(assign_map, module, cell, "empty", "\\Y", new_y);
goto next_cell;
}
if (new_a.size() < a.size() || new_b.size() < b.size()) {
cover_list("opt.opt_const.eqneq.resize", "$eq", "$ne", "$eqx", "$nex", cell->type.str());
cell->setPort("\\A", new_a);
cell->setPort("\\B", new_b);
cell->parameters["\\A_WIDTH"] = new_a.size();
cell->parameters["\\B_WIDTH"] = new_b.size();
}
}
if ((cell->type == "$eq" || cell->type == "$ne") && cell->parameters["\\Y_WIDTH"].as_int() == 1 &&
cell->parameters["\\A_WIDTH"].as_int() == 1 && cell->parameters["\\B_WIDTH"].as_int() == 1)
{
RTLIL::SigSpec a = assign_map(cell->getPort("\\A"));
RTLIL::SigSpec b = assign_map(cell->getPort("\\B"));
if (a.is_fully_const()) {
cover_list("opt.opt_const.eqneq.swapconst", "$eq", "$ne", cell->type.str());
RTLIL::SigSpec tmp = cell->getPort("\\A");
cell->setPort("\\A", cell->getPort("\\B"));
cell->setPort("\\B", tmp);
}
if (b.is_fully_const()) {
if (b.as_bool() == (cell->type == "$eq")) {
RTLIL::SigSpec input = b;
ACTION_DO("\\Y", cell->getPort("\\A"));
} else {
cover_list("opt.opt_const.eqneq.isnot", "$eq", "$ne", cell->type.str());
log("Replacing %s cell `%s' in module `%s' with inverter.\n", log_id(cell->type), log_id(cell), log_id(module));
cell->type = "$not";
cell->parameters.erase("\\B_WIDTH");
cell->parameters.erase("\\B_SIGNED");
cell->unsetPort("\\B");
did_something = true;
}
goto next_cell;
}
}
if (cell->type.in("$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx") && assign_map(cell->getPort("\\B")).is_fully_const())
{
bool sign_ext = cell->type == "$sshr" && cell->getParam("\\A_SIGNED").as_bool();
int shift_bits = assign_map(cell->getPort("\\B")).as_int(cell->type.in("$shift", "$shiftx") && cell->getParam("\\B_SIGNED").as_bool());
if (cell->type.in("$shl", "$sshl"))
shift_bits *= -1;
RTLIL::SigSpec sig_a = assign_map(cell->getPort("\\A"));
RTLIL::SigSpec sig_y(cell->type == "$shiftx" ? RTLIL::State::Sx : RTLIL::State::S0, cell->getParam("\\Y_WIDTH").as_int());
if (SIZE(sig_a) < SIZE(sig_y))
sig_a.extend(SIZE(sig_y), cell->getParam("\\A_SIGNED").as_bool());
for (int i = 0; i < SIZE(sig_y); i++) {
int idx = i + shift_bits;
if (0 <= idx && idx < SIZE(sig_a))
sig_y[i] = sig_a[idx];
else if (SIZE(sig_a) <= idx && sign_ext)
sig_y[i] = sig_a[SIZE(sig_a)-1];
}
cover_list("opt.opt_const.constshift", "$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx", cell->type.str());
log("Replacing %s cell `%s' (B=%s, SHR=%d) in module `%s' with fixed wiring: %s\n",
log_id(cell->type), log_id(cell), log_signal(assign_map(cell->getPort("\\B"))), shift_bits, log_id(module), log_signal(sig_y));
module->connect(cell->getPort("\\Y"), sig_y);
module->remove(cell);
did_something = true;
goto next_cell;
}
if (!keepdc)
{
bool identity_wrt_a = false;
bool identity_wrt_b = false;
if (cell->type == "$add" || cell->type == "$sub" || cell->type == "$or" || cell->type == "$xor")
{
RTLIL::SigSpec a = assign_map(cell->getPort("\\A"));
RTLIL::SigSpec b = assign_map(cell->getPort("\\B"));
if (cell->type != "$sub" && a.is_fully_const() && a.as_bool() == false)
identity_wrt_b = true;
if (b.is_fully_const() && b.as_bool() == false)
identity_wrt_a = true;
}
if (cell->type == "$shl" || cell->type == "$shr" || cell->type == "$sshl" || cell->type == "$sshr" || cell->type == "$shift" || cell->type == "$shiftx")
{
RTLIL::SigSpec b = assign_map(cell->getPort("\\B"));
if (b.is_fully_const() && b.as_bool() == false)
identity_wrt_a = true;
}
if (cell->type == "$mul")
{
RTLIL::SigSpec a = assign_map(cell->getPort("\\A"));
RTLIL::SigSpec b = assign_map(cell->getPort("\\B"));
if (a.is_fully_const() && a.size() <= 32 && a.as_int() == 1)
identity_wrt_b = true;
if (b.is_fully_const() && b.size() <= 32 && b.as_int() == 1)
identity_wrt_a = true;
}
if (cell->type == "$div")
{
RTLIL::SigSpec b = assign_map(cell->getPort("\\B"));
if (b.is_fully_const() && b.size() <= 32 && b.as_int() == 1)
identity_wrt_a = true;
}
if (identity_wrt_a || identity_wrt_b)
{
if (identity_wrt_a)
cover_list("opt.opt_const.identwrt.a", "$add", "$sub", "$or", "$xor", "$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx", "$mul", "$div", cell->type.str());
if (identity_wrt_b)
cover_list("opt.opt_const.identwrt.b", "$add", "$sub", "$or", "$xor", "$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx", "$mul", "$div", cell->type.str());
log("Replacing %s cell `%s' in module `%s' with identity for port %c.\n",
cell->type.c_str(), cell->name.c_str(), module->name.c_str(), identity_wrt_a ? 'A' : 'B');
if (!identity_wrt_a) {
cell->setPort("\\A", cell->getPort("\\B"));
cell->parameters.at("\\A_WIDTH") = cell->parameters.at("\\B_WIDTH");
cell->parameters.at("\\A_SIGNED") = cell->parameters.at("\\B_SIGNED");
}
cell->type = "$pos";
cell->unsetPort("\\B");
cell->parameters.erase("\\B_WIDTH");
cell->parameters.erase("\\B_SIGNED");
cell->check();
did_something = true;
goto next_cell;
}
}
if (mux_bool && (cell->type == "$mux" || cell->type == "$_MUX_") &&
cell->getPort("\\A") == RTLIL::SigSpec(0, 1) && cell->getPort("\\B") == RTLIL::SigSpec(1, 1)) {
cover_list("opt.opt_const.mux_bool", "$mux", "$_MUX_", cell->type.str());
replace_cell(assign_map, module, cell, "mux_bool", "\\Y", cell->getPort("\\S"));
goto next_cell;
}
if (mux_bool && (cell->type == "$mux" || cell->type == "$_MUX_") &&
cell->getPort("\\A") == RTLIL::SigSpec(1, 1) && cell->getPort("\\B") == RTLIL::SigSpec(0, 1)) {
cover_list("opt.opt_const.mux_invert", "$mux", "$_MUX_", cell->type.str());
log("Replacing %s cell `%s' in module `%s' with inverter.\n", log_id(cell->type), log_id(cell), log_id(module));
cell->setPort("\\A", cell->getPort("\\S"));
cell->unsetPort("\\B");
cell->unsetPort("\\S");
if (cell->type == "$mux") {
cell->parameters["\\A_WIDTH"] = cell->parameters["\\WIDTH"];
cell->parameters["\\Y_WIDTH"] = cell->parameters["\\WIDTH"];
cell->parameters["\\A_SIGNED"] = 0;
cell->parameters.erase("\\WIDTH");
cell->type = "$not";
} else
cell->type = "$_NOT_";
did_something = true;
goto next_cell;
}
if (consume_x && mux_bool && (cell->type == "$mux" || cell->type == "$_MUX_") && cell->getPort("\\A") == RTLIL::SigSpec(0, 1)) {
cover_list("opt.opt_const.mux_and", "$mux", "$_MUX_", cell->type.str());
log("Replacing %s cell `%s' in module `%s' with and-gate.\n", log_id(cell->type), log_id(cell), log_id(module));
cell->setPort("\\A", cell->getPort("\\S"));
cell->unsetPort("\\S");
if (cell->type == "$mux") {
cell->parameters["\\A_WIDTH"] = cell->parameters["\\WIDTH"];
cell->parameters["\\B_WIDTH"] = cell->parameters["\\WIDTH"];
cell->parameters["\\Y_WIDTH"] = cell->parameters["\\WIDTH"];
cell->parameters["\\A_SIGNED"] = 0;
cell->parameters["\\B_SIGNED"] = 0;
cell->parameters.erase("\\WIDTH");
cell->type = "$and";
} else
cell->type = "$_AND_";
did_something = true;
goto next_cell;
}
if (consume_x && mux_bool && (cell->type == "$mux" || cell->type == "$_MUX_") && cell->getPort("\\B") == RTLIL::SigSpec(1, 1)) {
cover_list("opt.opt_const.mux_or", "$mux", "$_MUX_", cell->type.str());
log("Replacing %s cell `%s' in module `%s' with or-gate.\n", log_id(cell->type), log_id(cell), log_id(module));
cell->setPort("\\B", cell->getPort("\\S"));
cell->unsetPort("\\S");
if (cell->type == "$mux") {
cell->parameters["\\A_WIDTH"] = cell->parameters["\\WIDTH"];
cell->parameters["\\B_WIDTH"] = cell->parameters["\\WIDTH"];
cell->parameters["\\Y_WIDTH"] = cell->parameters["\\WIDTH"];
cell->parameters["\\A_SIGNED"] = 0;
cell->parameters["\\B_SIGNED"] = 0;
cell->parameters.erase("\\WIDTH");
cell->type = "$or";
} else
cell->type = "$_OR_";
did_something = true;
goto next_cell;
}
if (mux_undef && (cell->type == "$mux" || cell->type == "$pmux")) {
RTLIL::SigSpec new_a, new_b, new_s;
int width = cell->getPort("\\A").size();
if ((cell->getPort("\\A").is_fully_undef() && cell->getPort("\\B").is_fully_undef()) ||
cell->getPort("\\S").is_fully_undef()) {
cover_list("opt.opt_const.mux_undef", "$mux", "$pmux", cell->type.str());
replace_cell(assign_map, module, cell, "mux_undef", "\\Y", cell->getPort("\\A"));
goto next_cell;
}
for (int i = 0; i < cell->getPort("\\S").size(); i++) {
RTLIL::SigSpec old_b = cell->getPort("\\B").extract(i*width, width);
RTLIL::SigSpec old_s = cell->getPort("\\S").extract(i, 1);
if (old_b.is_fully_undef() || old_s.is_fully_undef())
continue;
new_b.append(old_b);
new_s.append(old_s);
}
new_a = cell->getPort("\\A");
if (new_a.is_fully_undef() && new_s.size() > 0) {
new_a = new_b.extract((new_s.size()-1)*width, width);
new_b = new_b.extract(0, (new_s.size()-1)*width);
new_s = new_s.extract(0, new_s.size()-1);
}
if (new_s.size() == 0) {
cover_list("opt.opt_const.mux_empty", "$mux", "$pmux", cell->type.str());
replace_cell(assign_map, module, cell, "mux_empty", "\\Y", new_a);
goto next_cell;
}
if (new_a == RTLIL::SigSpec(RTLIL::State::S0) && new_b == RTLIL::SigSpec(RTLIL::State::S1)) {
cover_list("opt.opt_const.mux_sel01", "$mux", "$pmux", cell->type.str());
replace_cell(assign_map, module, cell, "mux_sel01", "\\Y", new_s);
goto next_cell;
}
if (cell->getPort("\\S").size() != new_s.size()) {
cover_list("opt.opt_const.mux_reduce", "$mux", "$pmux", cell->type.str());
log("Optimized away %d select inputs of %s cell `%s' in module `%s'.\n",
SIZE(cell->getPort("\\S")) - SIZE(new_s), log_id(cell->type), log_id(cell), log_id(module));
cell->setPort("\\A", new_a);
cell->setPort("\\B", new_b);
cell->setPort("\\S", new_s);
if (new_s.size() > 1) {
cell->type = "$pmux";
cell->parameters["\\S_WIDTH"] = new_s.size();
} else {
cell->type = "$mux";
cell->parameters.erase("\\S_WIDTH");
}
did_something = true;
}
}
#define FOLD_1ARG_CELL(_t) \
if (cell->type == "$" #_t) { \
RTLIL::SigSpec a = cell->getPort("\\A"); \
assign_map.apply(a); \
if (a.is_fully_const()) { \
RTLIL::Const dummy_arg(RTLIL::State::S0, 1); \
RTLIL::SigSpec y(RTLIL::const_ ## _t(a.as_const(), dummy_arg, \
cell->parameters["\\A_SIGNED"].as_bool(), false, \
cell->parameters["\\Y_WIDTH"].as_int())); \
cover("opt.opt_const.const.$" #_t); \
replace_cell(assign_map, module, cell, stringf("%s", log_signal(a)), "\\Y", y); \
goto next_cell; \
} \
}
#define FOLD_2ARG_CELL(_t) \
if (cell->type == "$" #_t) { \
RTLIL::SigSpec a = cell->getPort("\\A"); \
RTLIL::SigSpec b = cell->getPort("\\B"); \
assign_map.apply(a), assign_map.apply(b); \
if (a.is_fully_const() && b.is_fully_const()) { \
RTLIL::SigSpec y(RTLIL::const_ ## _t(a.as_const(), b.as_const(), \
cell->parameters["\\A_SIGNED"].as_bool(), \
cell->parameters["\\B_SIGNED"].as_bool(), \
cell->parameters["\\Y_WIDTH"].as_int())); \
cover("opt.opt_const.const.$" #_t); \
replace_cell(assign_map, module, cell, stringf("%s, %s", log_signal(a), log_signal(b)), "\\Y", y); \
goto next_cell; \
} \
}
FOLD_1ARG_CELL(not)
FOLD_2ARG_CELL(and)
FOLD_2ARG_CELL(or)
FOLD_2ARG_CELL(xor)
FOLD_2ARG_CELL(xnor)
FOLD_1ARG_CELL(reduce_and)
FOLD_1ARG_CELL(reduce_or)
FOLD_1ARG_CELL(reduce_xor)
FOLD_1ARG_CELL(reduce_xnor)
FOLD_1ARG_CELL(reduce_bool)
FOLD_1ARG_CELL(logic_not)
FOLD_2ARG_CELL(logic_and)
FOLD_2ARG_CELL(logic_or)
FOLD_2ARG_CELL(shl)
FOLD_2ARG_CELL(shr)
FOLD_2ARG_CELL(sshl)
FOLD_2ARG_CELL(sshr)
FOLD_2ARG_CELL(shift)
FOLD_2ARG_CELL(shiftx)
FOLD_2ARG_CELL(lt)
FOLD_2ARG_CELL(le)
FOLD_2ARG_CELL(eq)
FOLD_2ARG_CELL(ne)
FOLD_2ARG_CELL(gt)
FOLD_2ARG_CELL(ge)
FOLD_2ARG_CELL(add)
FOLD_2ARG_CELL(sub)
FOLD_2ARG_CELL(mul)
FOLD_2ARG_CELL(div)
FOLD_2ARG_CELL(mod)
FOLD_2ARG_CELL(pow)
FOLD_1ARG_CELL(pos)
FOLD_1ARG_CELL(neg)
// be very conservative with optimizing $mux cells as we do not want to break mux trees
if (cell->type == "$mux") {
RTLIL::SigSpec input = assign_map(cell->getPort("\\S"));
RTLIL::SigSpec inA = assign_map(cell->getPort("\\A"));
RTLIL::SigSpec inB = assign_map(cell->getPort("\\B"));
if (input.is_fully_const())
ACTION_DO("\\Y", input.as_bool() ? cell->getPort("\\B") : cell->getPort("\\A"));
else if (inA == inB)
ACTION_DO("\\Y", cell->getPort("\\A"));
}
if (!keepdc && cell->type == "$mul")
{
bool a_signed = cell->parameters["\\A_SIGNED"].as_bool();
bool b_signed = cell->parameters["\\B_SIGNED"].as_bool();
bool swapped_ab = false;
RTLIL::SigSpec sig_a = assign_map(cell->getPort("\\A"));
RTLIL::SigSpec sig_b = assign_map(cell->getPort("\\B"));
RTLIL::SigSpec sig_y = assign_map(cell->getPort("\\Y"));
if (sig_b.is_fully_const() && sig_b.size() <= 32)
std::swap(sig_a, sig_b), std::swap(a_signed, b_signed), swapped_ab = true;
if (sig_a.is_fully_def() && sig_a.size() <= 32)
{
int a_val = sig_a.as_int();
if (a_val == 0)
{
cover("opt.opt_const.mul_shift.zero");
log("Replacing multiply-by-zero cell `%s' in module `%s' with zero-driver.\n",
cell->name.c_str(), module->name.c_str());
module->connect(RTLIL::SigSig(sig_y, RTLIL::SigSpec(0, sig_y.size())));
module->remove(cell);
did_something = true;
goto next_cell;
}
for (int i = 1; i < (a_signed ? sig_a.size()-1 : sig_a.size()); i++)
if (a_val == (1 << i))
{
if (swapped_ab)
cover("opt.opt_const.mul_shift.swapped");
else
cover("opt.opt_const.mul_shift.unswapped");
log("Replacing multiply-by-%d cell `%s' in module `%s' with shift-by-%d.\n",
a_val, cell->name.c_str(), module->name.c_str(), i);
if (!swapped_ab) {
cell->setPort("\\A", cell->getPort("\\B"));
cell->parameters["\\A_WIDTH"] = cell->parameters["\\B_WIDTH"];
cell->parameters["\\A_SIGNED"] = cell->parameters["\\B_SIGNED"];
}
std::vector<RTLIL::SigBit> new_b = RTLIL::SigSpec(i, 6);
while (SIZE(new_b) > 1 && new_b.back() == RTLIL::State::S0)
new_b.pop_back();
cell->type = "$shl";
cell->parameters["\\B_WIDTH"] = SIZE(new_b);
cell->parameters["\\B_SIGNED"] = false;
cell->setPort("\\B", new_b);
cell->check();
did_something = true;
goto next_cell;
}
}
}
next_cell:;
#undef ACTION_DO
#undef ACTION_DO_Y
#undef FOLD_1ARG_CELL
#undef FOLD_2ARG_CELL
}
}
struct OptConstPass : public Pass {
OptConstPass() : Pass("opt_const", "perform const folding") { }
virtual void help()
{
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
log("\n");
log(" opt_const [options] [selection]\n");
log("\n");
log("This pass performs const folding on internal cell types with constant inputs.\n");
log("\n");
log(" -mux_undef\n");
log(" remove 'undef' inputs from $mux, $pmux and $_MUX_ cells\n");
log("\n");
log(" -mux_bool\n");
log(" replace $mux cells with inverters or buffers when possible\n");
log("\n");
log(" -undriven\n");
log(" replace undriven nets with undef (x) constants\n");
log("\n");
log(" -keepdc\n");
log(" some optimizations change the behavior of the circuit with respect to\n");
log(" don't-care bits. for example in 'a+0' a single x-bit in 'a' will cause\n");
log(" all result bits to be set to x. this behavior changes when 'a+0' is\n");
log(" replaced by 'a'. the -keepdc option disables all such optimizations.\n");
log("\n");
log(" -fine\n");
log(" perform fine-grain optimizations\n");
log("\n");
}
virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
{
bool mux_undef = false;
bool mux_bool = false;
bool undriven = false;
bool do_fine = false;
bool keepdc = false;
log_header("Executing OPT_CONST pass (perform const folding).\n");
log_push();
size_t argidx;
for (argidx = 1; argidx < args.size(); argidx++) {
if (args[argidx] == "-mux_undef") {
mux_undef = true;
continue;
}
if (args[argidx] == "-mux_bool") {
mux_bool = true;
continue;
}
if (args[argidx] == "-undriven") {
undriven = true;
continue;
}
if (args[argidx] == "-fine") {
do_fine = true;
continue;
}
if (args[argidx] == "-keepdc") {
keepdc = true;
continue;
}
break;
}
extra_args(args, argidx, design);
for (auto module : design->modules())
{
if (undriven)
replace_undriven(design, module);
do {
do {
did_something = false;
replace_const_cells(design, module, false, mux_undef, mux_bool, do_fine, keepdc);
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);
} while (did_something);
}
log_pop();
}
} OptConstPass;
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