yosys/passes/opt/opt_share.cc

573 lines
17 KiB
C++

/*
* yosys -- Yosys Open SYnthesis Suite
*
* Copyright (C) 2012 Clifford Wolf <clifford@clifford.at>
* 2019 Bogdan Vukobratovic <bogdan.vukobratovic@gmail.com>
*
* 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/log.h"
#include "kernel/register.h"
#include "kernel/rtlil.h"
#include "kernel/sigtools.h"
#include <algorithm>
#include <stdio.h>
#include <stdlib.h>
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
struct OpMuxConn {
RTLIL::SigSpec sig;
RTLIL::Cell *mux;
RTLIL::Cell *op;
int mux_port_id;
int mux_port_offset;
int op_outsig_offset;
bool operator<(const OpMuxConn &other) const
{
if (mux != other.mux)
return mux < other.mux;
if (mux_port_id != other.mux_port_id)
return mux_port_id < other.mux_port_id;
return mux_port_offset < other.mux_port_offset;
}
};
// Helper class to track additiona information about a SigSpec, like whether it is signed and the semantics of the port it is connected to
struct ExtSigSpec {
RTLIL::SigSpec sig;
RTLIL::SigSpec sign;
bool is_signed;
RTLIL::IdString semantics;
ExtSigSpec() {}
ExtSigSpec(RTLIL::SigSpec s, RTLIL::SigSpec sign = RTLIL::Const(0, 1), bool is_signed = false, RTLIL::IdString semantics = RTLIL::IdString()) : sig(s), sign(sign), is_signed(is_signed), semantics(semantics) {}
bool empty() const { return sig.empty(); }
bool operator<(const ExtSigSpec &other) const
{
if (sig != other.sig)
return sig < other.sig;
if (sign != other.sign)
return sign < other.sign;
if (is_signed != other.is_signed)
return is_signed < other.is_signed;
return semantics < other.semantics;
}
bool operator==(const RTLIL::SigSpec &other) const { return (sign != RTLIL::Const(0, 1)) ? false : sig == other; }
bool operator==(const ExtSigSpec &other) const { return is_signed == other.is_signed && sign == other.sign && sig == other.sig && semantics == other.semantics; }
};
#define FINE_BITWISE_OPS ID($_AND_), ID($_NAND_), ID($_OR_), ID($_NOR_), ID($_XOR_), ID($_XNOR_), ID($_ANDNOT_), ID($_ORNOT_)
#define BITWISE_OPS FINE_BITWISE_OPS, ID($and), ID($or), ID($xor), ID($xnor)
#define REDUCTION_OPS ID($reduce_and), ID($reduce_or), ID($reduce_xor), ID($reduce_xnor), ID($reduce_bool), ID($reduce_nand)
#define LOGICAL_OPS ID($logic_and), ID($logic_or)
#define SHIFT_OPS ID($shl), ID($shr), ID($sshl), ID($sshr), ID($shift), ID($shiftx)
#define RELATIONAL_OPS ID($lt), ID($le), ID($eq), ID($ne), ID($eqx), ID($nex), ID($ge), ID($gt)
bool cell_supported(RTLIL::Cell *cell)
{
if (cell->type.in(ID($alu))) {
RTLIL::SigSpec sig_bi = cell->getPort(ID::BI);
RTLIL::SigSpec sig_ci = cell->getPort(ID::CI);
if (sig_bi.is_fully_const() && sig_ci.is_fully_const() && sig_bi == sig_ci)
return true;
} else if (cell->type.in(LOGICAL_OPS, SHIFT_OPS, BITWISE_OPS, RELATIONAL_OPS, ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($divfloor), ID($modfloor), ID($concat))) {
return true;
}
return false;
}
std::map<IdString, IdString> mergeable_type_map;
bool mergeable(RTLIL::Cell *a, RTLIL::Cell *b)
{
if (mergeable_type_map.empty()) {
mergeable_type_map.insert({ID($sub), ID($add)});
}
auto a_type = a->type;
if (mergeable_type_map.count(a_type))
a_type = mergeable_type_map.at(a_type);
auto b_type = b->type;
if (mergeable_type_map.count(b_type))
b_type = mergeable_type_map.at(b_type);
return a_type == b_type;
}
RTLIL::IdString decode_port_semantics(RTLIL::Cell *cell, RTLIL::IdString port_name)
{
if (cell->type.in(ID($lt), ID($le), ID($ge), ID($gt), ID($div), ID($mod), ID($divfloor), ID($modfloor), ID($concat), SHIFT_OPS) && port_name == ID::B)
return port_name;
return "";
}
RTLIL::SigSpec decode_port_sign(RTLIL::Cell *cell, RTLIL::IdString port_name) {
if (cell->type == ID($alu) && port_name == ID::B)
return cell->getPort(ID::BI);
else if (cell->type == ID($sub) && port_name == ID::B)
return RTLIL::Const(1, 1);
return RTLIL::Const(0, 1);
}
bool decode_port_signed(RTLIL::Cell *cell, RTLIL::IdString port_name)
{
if (cell->type.in(BITWISE_OPS, LOGICAL_OPS))
return false;
if (cell->hasParam(port_name.str() + "_SIGNED"))
return cell->getParam(port_name.str() + "_SIGNED").as_bool();
return false;
}
ExtSigSpec decode_port(RTLIL::Cell *cell, RTLIL::IdString port_name, const SigMap &sigmap)
{
auto sig = sigmap(cell->getPort(port_name));
RTLIL::SigSpec sign = decode_port_sign(cell, port_name);
RTLIL::IdString semantics = decode_port_semantics(cell, port_name);
bool is_signed = decode_port_signed(cell, port_name);
return ExtSigSpec(sig, sign, is_signed, semantics);
}
void merge_operators(RTLIL::Module *module, RTLIL::Cell *mux, const std::vector<OpMuxConn> &ports, const ExtSigSpec &operand, const SigMap &sigmap)
{
std::vector<ExtSigSpec> muxed_operands;
int max_width = 0;
for (const auto& p : ports) {
auto op = p.op;
RTLIL::IdString muxed_port_name = ID::A;
if (decode_port(op, ID::A, sigmap) == operand)
muxed_port_name = ID::B;
auto operand = decode_port(op, muxed_port_name, sigmap);
if (operand.sig.size() > max_width)
max_width = operand.sig.size();
muxed_operands.push_back(operand);
}
auto shared_op = ports[0].op;
if (std::any_of(muxed_operands.begin(), muxed_operands.end(), [&](ExtSigSpec &op) { return op.sign != muxed_operands[0].sign; }))
max_width = std::max(max_width, shared_op->getParam(ID::Y_WIDTH).as_int());
for (auto &operand : muxed_operands) {
operand.sig.extend_u0(max_width, operand.is_signed);
if (operand.sign != muxed_operands[0].sign)
operand = ExtSigSpec(module->Neg(NEW_ID, operand.sig, operand.is_signed));
}
for (const auto& p : ports) {
auto op = p.op;
if (op == shared_op)
continue;
module->remove(op);
}
RTLIL::SigSpec mux_a = mux->getPort(ID::A);
RTLIL::SigSpec mux_b = mux->getPort(ID::B);
RTLIL::SigSpec mux_s = mux->getPort(ID::S);
int conn_width = ports[0].sig.size();
int conn_mux_offset = ports[0].mux_port_offset;
int conn_op_offset = ports[0].op_outsig_offset;
RTLIL::SigSpec shared_pmux_a = RTLIL::Const(RTLIL::State::Sx, max_width);
RTLIL::SigSpec shared_pmux_b;
RTLIL::SigSpec shared_pmux_s;
// Make a new wire to avoid false equivalence with whatever the former shared output was connected to.
Wire *new_out = module->addWire(NEW_ID, conn_op_offset + conn_width);
SigSpec new_sig_out = SigSpec(new_out, conn_op_offset, conn_width);
for (int i = 0; i < GetSize(ports); i++) {
auto &p = ports[i];
auto &op = muxed_operands[i];
if (p.mux_port_id == GetSize(mux_s)) {
shared_pmux_a = op.sig;
mux_a.replace(conn_mux_offset, new_sig_out);
} else {
shared_pmux_s.append(mux_s[p.mux_port_id]);
shared_pmux_b.append(op.sig);
mux_b.replace(p.mux_port_id * mux_a.size() + conn_mux_offset, new_sig_out);
}
}
mux->setPort(ID::A, mux_a);
mux->setPort(ID::B, mux_b);
mux->setPort(ID::S, mux_s);
SigSpec mux_to_oper;
if (GetSize(shared_pmux_s) == 1) {
mux_to_oper = module->Mux(NEW_ID, shared_pmux_a, shared_pmux_b, shared_pmux_s);
} else {
mux_to_oper = module->Pmux(NEW_ID, shared_pmux_a, shared_pmux_b, shared_pmux_s);
}
if (shared_op->type.in(ID($alu))) {
shared_op->setPort(ID::X, module->addWire(NEW_ID, GetSize(new_out)));
shared_op->setPort(ID::CO, module->addWire(NEW_ID, GetSize(new_out)));
}
bool is_fine = shared_op->type.in(FINE_BITWISE_OPS);
shared_op->setPort(ID::Y, new_out);
if (!is_fine)
shared_op->setParam(ID::Y_WIDTH, GetSize(new_out));
if (decode_port(shared_op, ID::A, sigmap) == operand) {
shared_op->setPort(ID::B, mux_to_oper);
if (!is_fine)
shared_op->setParam(ID::B_WIDTH, max_width);
} else {
shared_op->setPort(ID::A, mux_to_oper);
if (!is_fine)
shared_op->setParam(ID::A_WIDTH, max_width);
}
}
typedef struct {
RTLIL::Cell *mux;
std::vector<OpMuxConn> ports;
ExtSigSpec shared_operand;
} merged_op_t;
void check_muxed_operands(std::vector<const OpMuxConn *> &ports, const ExtSigSpec &shared_operand, const SigMap &sigmap)
{
auto it = ports.begin();
ExtSigSpec seed;
while (it != ports.end()) {
auto p = *it;
auto op = p->op;
RTLIL::IdString muxed_port_name = ID::A;
if (decode_port(op, ID::A, sigmap) == shared_operand) {
muxed_port_name = ID::B;
}
auto operand = decode_port(op, muxed_port_name, sigmap);
if (seed.empty())
seed = operand;
if (operand.is_signed != seed.is_signed) {
ports.erase(it);
} else {
++it;
}
}
}
ExtSigSpec find_shared_operand(const OpMuxConn* seed, std::vector<const OpMuxConn *> &ports, const std::map<ExtSigSpec, std::set<RTLIL::Cell *>> &operand_to_users, const SigMap &sigmap)
{
std::set<RTLIL::Cell *> ops_using_operand;
std::set<RTLIL::Cell *> ops_set;
for(const auto& p: ports)
ops_set.insert(p->op);
ExtSigSpec oper;
auto op_a = seed->op;
for (RTLIL::IdString port_name : {ID::A, ID::B}) {
oper = decode_port(op_a, port_name, sigmap);
auto operand_users = operand_to_users.at(oper);
if (operand_users.size() == 1)
continue;
ops_using_operand.clear();
for (auto mux_ops: ops_set)
if (operand_users.count(mux_ops))
ops_using_operand.insert(mux_ops);
if (ops_using_operand.size() > 1) {
ports.erase(std::remove_if(ports.begin(), ports.end(), [&](const OpMuxConn *p) { return !ops_using_operand.count(p->op); }),
ports.end());
return oper;
}
}
return ExtSigSpec();
}
struct OptSharePass : public Pass {
OptSharePass() : Pass("opt_share", "merge mutually exclusive cells of the same type that share an input signal") {}
void help() override
{
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
log("\n");
log(" opt_share [selection]\n");
log("\n");
log("This pass identifies mutually exclusive cells of the same type that:\n");
log(" (a) share an input signal,\n");
log(" (b) drive the same $mux, $_MUX_, or $pmux multiplexing cell,\n");
log("\n");
log("allowing the cell to be merged and the multiplexer to be moved from\n");
log("multiplexing its output to multiplexing the non-shared input signals.\n");
log("\n");
}
void execute(std::vector<std::string> args, RTLIL::Design *design) override
{
log_header(design, "Executing OPT_SHARE pass.\n");
extra_args(args, 1, design);
for (auto module : design->selected_modules()) {
SigMap sigmap(module);
dict<RTLIL::SigBit, int> bit_users;
for (auto cell : module->cells())
for (auto conn : cell->connections())
for (auto bit : conn.second)
bit_users[sigmap(bit)]++;
for (auto wire : module->wires())
if (wire->port_id != 0)
for (auto bit : SigSpec(wire))
bit_users[sigmap(bit)]++;
std::map<ExtSigSpec, std::set<RTLIL::Cell *>> operand_to_users;
dict<RTLIL::SigBit, std::pair<RTLIL::Cell *, int>> op_outbit_to_outsig;
bool any_shared_operands = false;
for (auto cell : module->selected_cells()) {
if (!cell_supported(cell))
continue;
bool skip = false;
if (cell->type == ID($alu)) {
for (RTLIL::IdString port_name : {ID::X, ID::CO}) {
for (auto outbit : sigmap(cell->getPort(port_name)))
if (bit_users[outbit] > 1)
skip = true;
}
}
if (skip)
continue;
auto mux_insig = sigmap(cell->getPort(ID::Y));
for (int i = 0; i < GetSize(mux_insig); i++)
op_outbit_to_outsig[mux_insig[i]] = std::make_pair(cell, i);
for (RTLIL::IdString port_name : {ID::A, ID::B}) {
auto op_insig = decode_port(cell, port_name, sigmap);
operand_to_users[op_insig].insert(cell);
if (operand_to_users[op_insig].size() > 1)
any_shared_operands = true;
}
}
if (!any_shared_operands)
continue;
// Operator outputs need to be exclusively connected to the $mux inputs in order to be mergeable. Hence we count to
// how many points are operator output bits connected.
std::vector<merged_op_t> merged_ops;
for (auto mux : module->selected_cells()) {
if (!mux->type.in(ID($mux), ID($_MUX_), ID($pmux)))
continue;
int mux_port_size = GetSize(mux->getPort(ID::A));
int mux_port_num = GetSize(mux->getPort(ID::S)) + 1;
RTLIL::SigSpec mux_insig = sigmap(RTLIL::SigSpec{mux->getPort(ID::B), mux->getPort(ID::A)});
std::vector<std::set<OpMuxConn>> mux_port_conns(mux_port_num);
int found = 0;
for (int mux_port_id = 0; mux_port_id < mux_port_num; mux_port_id++) {
SigSpec mux_insig;
if (mux_port_id == mux_port_num - 1) {
mux_insig = sigmap(mux->getPort(ID::A));
} else {
mux_insig = sigmap(mux->getPort(ID::B).extract(mux_port_id * mux_port_size, mux_port_size));
}
for (int mux_port_offset = 0; mux_port_offset < mux_port_size; ++mux_port_offset) {
if (!op_outbit_to_outsig.count(mux_insig[mux_port_offset]))
continue;
RTLIL::Cell *cell;
int op_outsig_offset;
std::tie(cell, op_outsig_offset) = op_outbit_to_outsig.at(mux_insig[mux_port_offset]);
SigSpec op_outsig = sigmap(cell->getPort(ID::Y));
int op_outsig_size = GetSize(op_outsig);
int op_conn_width = 0;
while (mux_port_offset + op_conn_width < mux_port_size &&
op_outsig_offset + op_conn_width < op_outsig_size &&
mux_insig[mux_port_offset + op_conn_width] == op_outsig[op_outsig_offset + op_conn_width])
op_conn_width++;
log_assert(op_conn_width >= 1);
bool skip = false;
for (int i = 0; i < op_outsig_size; i++) {
int expected = 1;
if (i >= op_outsig_offset && i < op_outsig_offset + op_conn_width)
expected = 2;
if (bit_users[op_outsig[i]] != expected)
skip = true;
}
if (skip) {
mux_port_offset += op_conn_width;
mux_port_offset--;
continue;
}
OpMuxConn inp = {
op_outsig.extract(op_outsig_offset, op_conn_width),
mux,
cell,
mux_port_id,
mux_port_offset,
op_outsig_offset,
};
mux_port_conns[mux_port_id].insert(inp);
mux_port_offset += op_conn_width;
mux_port_offset--;
found++;
}
}
if (found < 2)
continue;
const OpMuxConn *seed = NULL;
// Look through the bits of the $mux inputs and see which of them are connected to the operator
// results. Operator results can be concatenated with other signals before led to the $mux.
while (true) {
// Remove either the merged ports from the last iteration or the seed that failed to yield a merger
if (seed != NULL) {
mux_port_conns[seed->mux_port_id].erase(*seed);
seed = NULL;
}
// For a new merger, find the seed op connection that starts at lowest port offset among port connections
for (auto &port_conns : mux_port_conns) {
if (!port_conns.size())
continue;
const OpMuxConn *next_p = &(*port_conns.begin());
if ((seed == NULL) || (seed->mux_port_offset > next_p->mux_port_offset))
seed = next_p;
}
// Cannot find the seed -> nothing to do for this $mux anymore
if (seed == NULL)
break;
// Find all other op connections that start from the same port offset, and whose ops can be merged with the seed op
std::vector<const OpMuxConn *> mergeable_conns;
for (auto &port_conns : mux_port_conns) {
if (!port_conns.size())
continue;
const OpMuxConn *next_p = &(*port_conns.begin());
if ((next_p->op_outsig_offset == seed->op_outsig_offset) &&
(next_p->mux_port_offset == seed->mux_port_offset) && mergeable(next_p->op, seed->op) &&
next_p->sig.size() == seed->sig.size())
mergeable_conns.push_back(next_p);
}
// We need at least two mergeable connections for the merger
if (mergeable_conns.size() < 2)
continue;
// Filter mergeable connections whose ops share an operand with seed connection's op
auto shared_operand = find_shared_operand(seed, mergeable_conns, operand_to_users, sigmap);
if (shared_operand.empty())
continue;
check_muxed_operands(mergeable_conns, shared_operand, sigmap);
if (mergeable_conns.size() < 2)
continue;
// Remember the combination for the merger
std::vector<OpMuxConn> merged_ports;
for (auto p : mergeable_conns) {
merged_ports.push_back(*p);
mux_port_conns[p->mux_port_id].erase(*p);
}
seed = NULL;
merged_ops.push_back(merged_op_t{mux, merged_ports, shared_operand});
design->scratchpad_set_bool("opt.did_something", true);
}
}
for (auto &shared : merged_ops) {
log(" Found cells that share an operand and can be merged by moving the %s %s in front "
"of "
"them:\n",
log_id(shared.mux->type), log_id(shared.mux));
for (const auto& op : shared.ports)
log(" %s\n", log_id(op.op));
log("\n");
merge_operators(module, shared.mux, shared.ports, shared.shared_operand, sigmap);
}
}
}
} OptSharePass;
PRIVATE_NAMESPACE_END