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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 "opt_status.h"
#include "kernel/register.h"
#include "kernel/sigtools.h"
#include "kernel/celltypes.h"
#include "kernel/log.h"
#include <stdlib.h>
#include <assert.h>
#include <stdio.h>
#include <set>
static bool did_something;
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 &it : module->cells)
for (auto &conn : it.second->connections) {
if (!ct.cell_known(it.second->type) || ct.cell_output(it.second->type, conn.first))
driven_signals.add(sigmap(conn.second));
if (!ct.cell_known(it.second->type) || ct.cell_input(it.second->type, conn.first))
used_signals.add(sigmap(conn.second));
}
for (auto &it : module->wires) {
if (it.second->port_input)
driven_signals.add(sigmap(it.second));
if (it.second->port_output)
used_signals.add(sigmap(it.second));
all_signals.add(sigmap(it.second));
}
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] == '$')
sig = used_signals.extract(sig);
if (sig.width == 0)
continue;
log("Setting undriven signal in %s to undef: %s\n", RTLIL::id2cstr(module->name), log_signal(c));
module->connections.push_back(RTLIL::SigSig(c, RTLIL::SigSpec(RTLIL::State::Sx, c.width)));
OPT_DID_SOMETHING = true;
}
}
void replace_cell(RTLIL::Module *module, RTLIL::Cell *cell, std::string info, std::string out_port, RTLIL::SigSpec out_val)
{
RTLIL::SigSpec Y = cell->connections[out_port];
log("Replacing %s cell `%s' (%s) in module `%s' with constant driver `%s = %s'.\n",
cell->type.c_str(), cell->name.c_str(), info.c_str(),
module->name.c_str(), log_signal(Y), log_signal(out_val));
// ILANG_BACKEND::dump_cell(stderr, "--> ", cell);
module->connections.push_back(RTLIL::SigSig(Y, out_val));
module->cells.erase(cell->name);
delete cell;
OPT_DID_SOMETHING = true;
did_something = true;
}
void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool consume_x, bool mux_undef, bool mux_bool)
{
if (!design->selected(module))
return;
SigMap assign_map(module);
std::map<RTLIL::SigSpec, RTLIL::SigSpec> invert_map;
std::vector<RTLIL::Cell*> cells;
cells.reserve(module->cells.size());
for (auto &cell_it : module->cells)
if (design->selected(module, cell_it.second)) {
if ((cell_it.second->type == "$_INV_" || cell_it.second->type == "$not" || cell_it.second->type == "$logic_not") &&
cell_it.second->connections["\\A"].width == 1 && cell_it.second->connections["\\Y"].width == 1)
invert_map[assign_map(cell_it.second->connections["\\Y"])] = assign_map(cell_it.second->connections["\\A"]);
cells.push_back(cell_it.second);
}
for (auto cell : cells)
{
#define ACTION_DO(_p_, _s_) do { replace_cell(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 ((cell->type == "$_INV_" || cell->type == "$not" || cell->type == "$logic_not") && cell->connections["\\Y"].width == 1 &&
invert_map.count(assign_map(cell->connections["\\A"])) != 0) {
replace_cell(module, cell, "double_invert", "\\Y", invert_map.at(assign_map(cell->connections["\\A"])));
goto next_cell;
}
if ((cell->type == "$_MUX_" || cell->type == "$mux") && invert_map.count(assign_map(cell->connections["\\S"])) != 0) {
RTLIL::SigSpec tmp = cell->connections["\\A"];
cell->connections["\\A"] = cell->connections["\\B"];
cell->connections["\\B"] = tmp;
cell->connections["\\S"] = invert_map.at(assign_map(cell->connections["\\S"]));
OPT_DID_SOMETHING = true;
did_something = true;
goto next_cell;
}
if (cell->type == "$_INV_") {
RTLIL::SigSpec input = cell->connections["\\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 == "$_AND_") {
RTLIL::SigSpec input;
input.append(cell->connections["\\B"]);
input.append(cell->connections["\\A"]);
assign_map.apply(input);
if (input.match(" 0")) ACTION_DO_Y(0);
if (input.match("0 ")) ACTION_DO_Y(0);
if (input.match("11")) ACTION_DO_Y(1);
if (input.match("**")) ACTION_DO_Y(x);
if (input.match("1*")) ACTION_DO_Y(x);
if (input.match("*1")) ACTION_DO_Y(x);
if (consume_x) {
if (input.match(" *")) ACTION_DO_Y(0);
if (input.match("* ")) ACTION_DO_Y(0);
}
if (input.match(" 1")) ACTION_DO("\\Y", input.extract(1, 1));
if (input.match("1 ")) ACTION_DO("\\Y", input.extract(0, 1));
}
if (cell->type == "$_OR_") {
RTLIL::SigSpec input;
input.append(cell->connections["\\B"]);
input.append(cell->connections["\\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 == "$_XOR_") {
RTLIL::SigSpec input;
input.append(cell->connections["\\B"]);
input.append(cell->connections["\\A"]);
assign_map.apply(input);
if (input.match("00")) ACTION_DO_Y(0);
if (input.match("01")) ACTION_DO_Y(1);
if (input.match("10")) ACTION_DO_Y(1);
if (input.match("11")) ACTION_DO_Y(0);
if (input.match(" *")) ACTION_DO_Y(x);
if (input.match("* ")) ACTION_DO_Y(x);
if (input.match(" 0")) ACTION_DO("\\Y", input.extract(1, 1));
if (input.match("0 ")) ACTION_DO("\\Y", input.extract(0, 1));
}
if (cell->type == "$_MUX_") {
RTLIL::SigSpec input;
input.append(cell->connections["\\S"]);
input.append(cell->connections["\\B"]);
input.append(cell->connections["\\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 ")) {
cell->type = "$_INV_";
cell->connections["\\A"] = input.extract(0, 1);
cell->connections.erase("\\B");
cell->connections.erase("\\S");
goto next_cell;
}
if (input.match("11 ")) ACTION_DO_Y(1);
if (input.match("00 ")) ACTION_DO_Y(0);
if (input.match("** ")) ACTION_DO_Y(x);
if (input.match("01*")) ACTION_DO_Y(x);
if (input.match("10*")) ACTION_DO_Y(x);
if (mux_undef) {
if (input.match("* ")) ACTION_DO("\\Y", input.extract(1, 1));
if (input.match(" * ")) ACTION_DO("\\Y", input.extract(2, 1));
if (input.match(" *")) ACTION_DO("\\Y", input.extract(2, 1));
}
}
if (cell->type == "$eq" || cell->type == "$ne" || cell->type == "$eqx" || cell->type == "$nex")
{
RTLIL::SigSpec a = cell->connections["\\A"];
RTLIL::SigSpec b = cell->connections["\\B"];
if (cell->parameters["\\A_WIDTH"].as_int() != cell->parameters["\\B_WIDTH"].as_int()) {
int width = std::max(cell->parameters["\\A_WIDTH"].as_int(), cell->parameters["\\B_WIDTH"].as_int());
a.extend_u0(width, cell->parameters["\\A_SIGNED"].as_bool() && cell->parameters["\\B_SIGNED"].as_bool());
b.extend_u0(width, cell->parameters["\\A_SIGNED"].as_bool() && cell->parameters["\\B_SIGNED"].as_bool());
}
RTLIL::SigSpec new_a, new_b;
a.expand(), b.expand();
assert(a.chunks.size() == b.chunks.size());
for (size_t i = 0; i < a.chunks.size(); i++) {
if (a.chunks[i].wire == NULL && b.chunks[i].wire == NULL && a.chunks[i].data.bits[0] != b.chunks[i].data.bits[0] &&
a.chunks[i].data.bits[0] <= RTLIL::State::S1 && b.chunks[i].data.bits[0] <= RTLIL::State::S1) {
RTLIL::SigSpec new_y = RTLIL::SigSpec((cell->type == "$eq" || cell->type == "$eqx") ? RTLIL::State::S0 : RTLIL::State::S1);
new_y.extend(cell->parameters["\\Y_WIDTH"].as_int(), false);
replace_cell(module, cell, "empty", "\\Y", new_y);
goto next_cell;
}
if (a.chunks[i] == b.chunks[i])
continue;
new_a.append(a.chunks[i]);
new_b.append(b.chunks[i]);
}
if (new_a.width == 0) {
RTLIL::SigSpec new_y = RTLIL::SigSpec((cell->type == "$eq" || cell->type == "$eqx") ? RTLIL::State::S1 : RTLIL::State::S0);
new_y.extend(cell->parameters["\\Y_WIDTH"].as_int(), false);
replace_cell(module, cell, "empty", "\\Y", new_y);
goto next_cell;
}
if (new_a.width < a.width || new_b.width < b.width) {
new_a.optimize();
new_b.optimize();
cell->connections["\\A"] = new_a;
cell->connections["\\B"] = new_b;
cell->parameters["\\A_WIDTH"] = new_a.width;
cell->parameters["\\B_WIDTH"] = new_b.width;
}
}
if ((cell->type == "$eq" || cell->type == "$ne") && cell->parameters["\\Y_WIDTH"].as_int() == 1 &&
cell->parameters["\\A_WIDTH"].as_int() == 1 && cell->parameters["\\B_WIDTH"].as_int() == 1)
{
RTLIL::SigSpec a = assign_map(cell->connections["\\A"]);
RTLIL::SigSpec b = assign_map(cell->connections["\\B"]);
if (a.is_fully_const()) {
RTLIL::SigSpec tmp;
tmp = a, a = b, b = tmp;
cell->connections["\\A"] = a;
cell->connections["\\B"] = b;
}
if (b.is_fully_const()) {
if (b.as_bool() == (cell->type == "$eq")) {
RTLIL::SigSpec input = b;
ACTION_DO("\\Y", cell->connections["\\A"]);
} else {
cell->type = "$not";
cell->parameters.erase("\\B_WIDTH");
cell->parameters.erase("\\B_SIGNED");
cell->connections.erase("\\B");
}
goto next_cell;
}
}
if (mux_bool && (cell->type == "$mux" || cell->type == "$_MUX_") &&
cell->connections["\\A"] == RTLIL::SigSpec(0, 1) && cell->connections["\\B"] == RTLIL::SigSpec(1, 1)) {
replace_cell(module, cell, "mux_bool", "\\Y", cell->connections["\\S"]);
goto next_cell;
}
if (mux_bool && (cell->type == "$mux" || cell->type == "$_MUX_") &&
cell->connections["\\A"] == RTLIL::SigSpec(1, 1) && cell->connections["\\B"] == RTLIL::SigSpec(0, 1)) {
cell->connections["\\A"] = cell->connections["\\S"];
cell->connections.erase("\\B");
cell->connections.erase("\\S");
if (cell->type == "$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 = "$not";
} else
cell->type = "$_INV_";
OPT_DID_SOMETHING = true;
did_something = true;
goto next_cell;
}
if (consume_x && mux_bool && (cell->type == "$mux" || cell->type == "$_MUX_") && cell->connections["\\A"] == RTLIL::SigSpec(0, 1)) {
cell->connections["\\A"] = cell->connections["\\S"];
cell->connections.erase("\\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 = "$_AND_";
OPT_DID_SOMETHING = true;
did_something = true;
goto next_cell;
}
if (consume_x && mux_bool && (cell->type == "$mux" || cell->type == "$_MUX_") && cell->connections["\\B"] == RTLIL::SigSpec(1, 1)) {
cell->connections["\\B"] = cell->connections["\\S"];
cell->connections.erase("\\S");
if (cell->type == "$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_";
OPT_DID_SOMETHING = true;
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->connections.at("\\A").width;
if ((cell->connections.at("\\A").is_fully_undef() && cell->connections.at("\\B").is_fully_undef()) ||
cell->connections.at("\\S").is_fully_undef()) {
replace_cell(module, cell, "mux undef", "\\Y", cell->connections.at("\\A"));
goto next_cell;
}
for (int i = 0; i < cell->connections.at("\\S").width; i++) {
RTLIL::SigSpec old_b = cell->connections.at("\\B").extract(i*width, width);
RTLIL::SigSpec old_s = cell->connections.at("\\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->connections.at("\\A");
if (new_a.is_fully_undef() && new_s.width > 0) {
new_a = new_b.extract((new_s.width-1)*width, width);
new_b = new_b.extract(0, (new_s.width-1)*width);
new_s = new_s.extract(0, new_s.width-1);
}
if (new_s.width == 0) {
replace_cell(module, cell, "mux undef", "\\Y", new_a);
goto next_cell;
}
if (new_a == RTLIL::SigSpec(RTLIL::State::S0) && new_b == RTLIL::SigSpec(RTLIL::State::S1)) {
replace_cell(module, cell, "mux undef", "\\Y", new_s);
goto next_cell;
}
if (cell->connections.at("\\S").width != new_s.width) {
cell->connections.at("\\A") = new_a;
cell->connections.at("\\B") = new_b;
cell->connections.at("\\S") = new_s;
if (new_s.width > 1) {
cell->type = "$pmux";
cell->parameters["\\S_WIDTH"] = new_s.width;
} else {
cell->type = "$mux";
cell->parameters.erase("\\S_WIDTH");
}
OPT_DID_SOMETHING = true;
did_something = true;
}
}
#define FOLD_1ARG_CELL(_t) \
if (cell->type == "$" #_t) { \
RTLIL::SigSpec a = cell->connections["\\A"]; \
assign_map.apply(a); \
if (a.is_fully_const()) { \
a.optimize(); \
if (a.chunks.empty()) a.chunks.push_back(RTLIL::SigChunk()); \
RTLIL::Const dummy_arg(RTLIL::State::S0, 1); \
RTLIL::SigSpec y(RTLIL::const_ ## _t(a.chunks[0].data, dummy_arg, \
cell->parameters["\\A_SIGNED"].as_bool(), false, \
cell->parameters["\\Y_WIDTH"].as_int())); \
replace_cell(module, cell, stringf("%s", log_signal(a)), "\\Y", y); \
goto next_cell; \
} \
}
#define FOLD_2ARG_CELL(_t) \
if (cell->type == "$" #_t) { \
RTLIL::SigSpec a = cell->connections["\\A"]; \
RTLIL::SigSpec b = cell->connections["\\B"]; \
assign_map.apply(a), assign_map.apply(b); \
if (a.is_fully_const() && b.is_fully_const()) { \
a.optimize(), b.optimize(); \
if (a.chunks.empty()) a.chunks.push_back(RTLIL::SigChunk()); \
if (b.chunks.empty()) b.chunks.push_back(RTLIL::SigChunk()); \
RTLIL::SigSpec y(RTLIL::const_ ## _t(a.chunks[0].data, b.chunks[0].data, \
cell->parameters["\\A_SIGNED"].as_bool(), \
cell->parameters["\\B_SIGNED"].as_bool(), \
cell->parameters["\\Y_WIDTH"].as_int())); \
replace_cell(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(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->connections["\\S"]);
RTLIL::SigSpec inA = assign_map(cell->connections["\\A"]);
RTLIL::SigSpec inB = assign_map(cell->connections["\\B"]);
if (input.is_fully_const())
ACTION_DO("\\Y", input.as_bool() ? cell->connections["\\B"] : cell->connections["\\A"]);
else if (inA == inB)
ACTION_DO("\\Y", cell->connections["\\A"]);
}
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");
}
virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
{
bool mux_undef = false;
bool mux_bool = false;
bool undriven = 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;
}
break;
}
extra_args(args, argidx, design);
for (auto &mod_it : design->modules)
{
if (undriven)
replace_undriven(design, mod_it.second);
do {
do {
did_something = false;
replace_const_cells(design, mod_it.second, false, mux_undef, mux_bool);
} while (did_something);
replace_const_cells(design, mod_it.second, true, mux_undef, mux_bool);
} while (did_something);
}
log_pop();
}
} OptConstPass;
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