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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/yosys.h"
#include "kernel/sigtools.h"
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
struct Pmux2ShiftxPass : public Pass {
Pmux2ShiftxPass() : Pass("pmux2shiftx", "transform $pmux cells to $shiftx cells") { }
void help() YS_OVERRIDE
{
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
log("\n");
log(" pmux2shiftx [options] [selection]\n");
log("\n");
log("This pass transforms $pmux cells to $shiftx cells.\n");
log("\n");
log(" -min_density <non_offset_percentage> <offset_percentage>\n");
log(" specifies the minimum density for non_offset- and for offset-mode\n");
log(" default values are 30 (non-offset) and 50 (offset)\n");
log("\n");
log(" -min_choices <int>\n");
log(" specified the minimum number of choices for a control signal\n");
log(" defaukt: 3\n");
log("\n");
log(" -allow_onehot\n");
log(" by default, pmuxes with one-hot encoded control signals are not\n");
log(" converted. this option disables that check.\n");
log("\n");
}
void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
{
int min_non_offset_percentage = 30;
int min_offset_percentage = 50;
int min_choices = 3;
bool allow_onehot = false;
log_header(design, "Executing PMUX2SHIFTX pass.\n");
size_t argidx;
for (argidx = 1; argidx < args.size(); argidx++) {
if (args[argidx] == "-min_density" && argidx+2 < args.size()) {
min_non_offset_percentage = atoi(args[++argidx].c_str());
min_offset_percentage = atoi(args[++argidx].c_str());
continue;
}
if (args[argidx] == "-min_choices" && argidx+1 < args.size()) {
min_choices = atoi(args[++argidx].c_str());
continue;
}
if (args[argidx] == "-allow_onehot") {
allow_onehot = true;
continue;
}
break;
}
extra_args(args, argidx, design);
for (auto module : design->selected_modules())
{
SigMap sigmap(module);
dict<SigBit, pair<SigSpec, Const>> eqdb;
for (auto cell : module->selected_cells())
{
if (cell->type == "$eq")
{
dict<SigBit, State> bits;
SigSpec A = sigmap(cell->getPort("\\A"));
SigSpec B = sigmap(cell->getPort("\\B"));
int a_width = cell->getParam("\\A_WIDTH").as_int();
int b_width = cell->getParam("\\B_WIDTH").as_int();
if (a_width < b_width) {
bool a_signed = cell->getParam("\\A_SIGNED").as_int();
A.extend_u0(b_width, a_signed);
}
if (b_width < a_width) {
bool b_signed = cell->getParam("\\B_SIGNED").as_int();
B.extend_u0(a_width, b_signed);
}
for (int i = 0; i < GetSize(A); i++) {
SigBit a_bit = A[i], b_bit = B[i];
if (b_bit.wire && !a_bit.wire) {
std::swap(a_bit, b_bit);
}
if (!a_bit.wire || b_bit.wire)
goto next_cell;
if (bits.count(a_bit))
goto next_cell;
bits[a_bit] = b_bit.data;
}
if (GetSize(bits) > 20)
goto next_cell;
bits.sort();
pair<SigSpec, Const> entry;
for (auto it : bits) {
entry.first.append_bit(it.first);
entry.second.bits.push_back(it.second);
}
eqdb[sigmap(cell->getPort("\\Y")[0])] = entry;
goto next_cell;
}
if (cell->type == "$logic_not")
{
dict<SigBit, State> bits;
SigSpec A = sigmap(cell->getPort("\\A"));
for (int i = 0; i < GetSize(A); i++)
bits[A[i]] = State::S0;
bits.sort();
pair<SigSpec, Const> entry;
for (auto it : bits) {
entry.first.append_bit(it.first);
entry.second.bits.push_back(it.second);
}
eqdb[sigmap(cell->getPort("\\Y")[0])] = entry;
goto next_cell;
}
next_cell:;
}
for (auto cell : module->selected_cells())
{
if (cell->type != "$pmux")
continue;
string src = cell->get_src_attribute();
int width = cell->getParam("\\WIDTH").as_int();
int width_bits = ceil_log2(width);
int extwidth = width;
while (extwidth & (extwidth-1))
extwidth++;
dict<SigSpec, pool<int>> seldb;
SigSpec B = cell->getPort("\\B");
SigSpec S = sigmap(cell->getPort("\\S"));
for (int i = 0; i < GetSize(S); i++)
{
if (!eqdb.count(S[i]))
continue;
auto &entry = eqdb.at(S[i]);
seldb[entry.first].insert(i);
}
if (seldb.empty())
continue;
bool printed_pmux_header = false;
SigSpec updated_S = cell->getPort("\\S");
SigSpec updated_B = cell->getPort("\\B");
while (!seldb.empty())
{
// pick the largest entry in seldb
SigSpec sig = seldb.begin()->first;
for (auto &it : seldb) {
if (GetSize(sig) < GetSize(it.first))
sig = it.first;
else if (GetSize(seldb.at(sig)) < GetSize(it.second))
sig = it.first;
}
// find the relevant choices
bool is_onehot = true;
dict<Const, int> choices;
for (int i : seldb.at(sig)) {
Const val = eqdb.at(S[i]).second;
int onebits = 0;
for (auto b : val.bits)
if (b == State::S1)
onebits++;
if (onebits > 1)
is_onehot = false;
choices[val] = i;
}
// TBD: also find choices that are using signals that are subsets of the bits in "sig"
if (is_onehot && !allow_onehot) {
seldb.erase(sig);
continue;
}
if (GetSize(choices) < min_choices) {
seldb.erase(sig);
continue;
}
if (!printed_pmux_header) {
printed_pmux_header = true;
log("Inspecting $pmux cell %s/%s.\n", log_id(module), log_id(cell));
log(" data width: %d (next power-of-2 = %d, log2 = %d)\n", width, extwidth, width_bits);
}
log(" checking ctrl signal %s\n", log_signal(sig));
// find the best permutation
vector<int> perm_new_from_old(GetSize(sig));
Const perm_xormask(State::S0, GetSize(sig));
{
vector<int> values(GetSize(choices));
vector<bool> used_src_columns(GetSize(sig));
vector<vector<bool>> columns(GetSize(sig), vector<bool>(GetSize(values)));
for (int i = 0; i < GetSize(choices); i++) {
Const val = choices.element(i)->first;
for (int k = 0; k < GetSize(val); k++)
if (val[k] == State::S1)
columns[k][i] = true;
}
for (int dst_col = GetSize(sig)-1; dst_col >= 0; dst_col--)
{
int best_src_col = -1;
bool best_inv = false;
int best_maxval = 0;
int best_delta = 0;
// find best src colum for this dst column
for (int src_col = 0; src_col < GetSize(sig); src_col++)
{
if (used_src_columns[src_col])
continue;
int this_maxval = 0;
int this_minval = 1 << 30;
int this_inv_maxval = 0;
int this_inv_minval = 1 << 30;
for (int i = 0; i < GetSize(values); i++)
{
int val = values[i];
int inv_val = val;
if (columns[src_col][i])
val |= 1 << dst_col;
else
inv_val |= 1 << dst_col;
this_maxval = std::max(this_maxval, val);
this_minval = std::min(this_minval, val);
this_inv_maxval = std::max(this_inv_maxval, inv_val);
this_inv_minval = std::min(this_inv_minval, inv_val);
}
int this_delta = this_maxval - this_minval;
int this_inv_delta = this_maxval - this_minval;
bool this_inv = false;
if (this_delta != this_inv_delta)
this_inv = this_inv_delta < this_delta;
else if (this_maxval != this_inv_maxval)
this_inv = this_inv_maxval < this_maxval;
if (this_inv) {
this_delta = this_inv_delta;
this_maxval = this_inv_maxval;
this_minval = this_inv_minval;
}
bool this_is_better = false;
if (best_src_col < 0)
this_is_better = true;
else if (this_delta != best_delta)
this_is_better = this_delta < best_delta;
else if (this_maxval != best_maxval)
this_is_better = this_maxval < best_maxval;
else
this_is_better = sig[best_src_col] < sig[src_col];
if (this_is_better) {
best_src_col = src_col;
best_inv = this_inv;
best_maxval = this_maxval;
best_delta = this_delta;
}
}
used_src_columns[best_src_col] = true;
perm_new_from_old[dst_col] = best_src_col;
perm_xormask[dst_col] = best_inv ? State::S1 : State::S0;
}
}
// permutated sig
SigSpec perm_sig(State::S0, GetSize(sig));
for (int i = 0; i < GetSize(sig); i++)
perm_sig[i] = sig[perm_new_from_old[i]];
log(" best permutation: %s\n", log_signal(perm_sig));
log(" best xor mask: %s\n", log_signal(perm_xormask));
// permutated choices
int min_choice = 1 << 30;
int max_choice = -1;
dict<Const, int> perm_choices;
for (auto &it : choices)
{
Const &old_c = it.first;
Const new_c(State::S0, GetSize(old_c));
for (int i = 0; i < GetSize(old_c); i++)
new_c[i] = old_c[perm_new_from_old[i]];
Const new_c_before_xor = new_c;
new_c = const_xor(new_c, perm_xormask, false, false, GetSize(new_c));
perm_choices[new_c] = it.second;
min_choice = std::min(min_choice, new_c.as_int());
max_choice = std::max(max_choice, new_c.as_int());
log(" %3d: %s -> %s -> %s: %s\n", it.second, log_signal(old_c), log_signal(new_c_before_xor),
log_signal(new_c), log_signal(B.extract(it.second*width, width)));
}
int range_density = 100*GetSize(choices) / (max_choice-min_choice+1);
int absolute_density = 100*GetSize(choices) / (max_choice+1);
log(" choices: %d\n", GetSize(choices));
log(" min choice: %d\n", min_choice);
log(" max choice: %d\n", max_choice);
log(" range density: %d%%\n", range_density);
log(" absolute density: %d%%\n", absolute_density);
bool full_case = (min_choice == 0) && (max_choice == (1 << GetSize(sig))-1) && (max_choice+1 == GetSize(choices));
log(" full case: %s\n", full_case ? "true" : "false");
// check density percentages
Const offset(State::S0, GetSize(sig));
if (absolute_density < min_non_offset_percentage && range_density >= min_offset_percentage)
{
offset = Const(min_choice, GetSize(sig));
log(" offset: %s\n", log_signal(offset));
min_choice -= offset.as_int();
max_choice -= offset.as_int();
dict<Const, int> new_perm_choices;
for (auto &it : perm_choices)
new_perm_choices[const_sub(it.first, offset, false, false, GetSize(sig))] = it.second;
perm_choices.swap(new_perm_choices);
} else
if (absolute_density < min_non_offset_percentage) {
log(" insufficient density.\n");
seldb.erase(sig);
continue;
}
// creat cmp signal
SigSpec cmp = perm_sig;
if (perm_xormask.as_bool())
cmp = module->Xor(NEW_ID, cmp, perm_xormask, false, src);
if (offset.as_bool())
cmp = module->Sub(NEW_ID, cmp, offset, false, src);
// create enable signal
SigBit en = State::S1;
if (!full_case) {
Const enable_mask(State::S0, max_choice+1);
for (auto &it : perm_choices)
enable_mask[it.first.as_int()] = State::S1;
en = module->addWire(NEW_ID);
module->addShift(NEW_ID, enable_mask, cmp, en, false, src);
}
// create data signal
SigSpec data(State::Sx, (max_choice+1)*extwidth);
for (auto &it : perm_choices) {
int position = it.first.as_int()*extwidth;
int data_index = it.second;
data.replace(position, B.extract(data_index*width, width));
updated_S[data_index] = State::S0;
updated_B.replace(data_index*width, SigSpec(State::Sx, width));
}
// create shiftx cell
SigSpec shifted_cmp = {cmp, SigSpec(State::S0, width_bits)};
SigSpec outsig = module->addWire(NEW_ID, width);
Cell *c = module->addShiftx(NEW_ID, data, shifted_cmp, outsig, false, src);
updated_S.append(en);
updated_B.append(outsig);
log(" created $shiftx cell %s.\n", log_id(c));
// remove this sig and continue with the next block
seldb.erase(sig);
}
// update $pmux cell
cell->setPort("\\S", updated_S);
cell->setPort("\\B", updated_B);
cell->setParam("\\S_WIDTH", GetSize(updated_S));
}
}
}
} Pmux2ShiftxPass;
PRIVATE_NAMESPACE_END
|