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Improvements in "pmux2shiftx"

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Signed-off-by: Clifford Wolf <clifford@clifford.at>
This commit is contained in:
Clifford Wolf 2019-04-20 01:15:48 +02:00
parent 0070184ea9
commit 37728520a6
2 changed files with 53 additions and 13 deletions
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64
passes/opt/pmux2shiftx.cc
View file

@ -33,23 +33,41 @@ struct Pmux2ShiftxPass : public Pass {
log("\n");
log("This pass transforms $pmux cells to $shiftx cells.\n");
log("\n");
log(" -density non_offset_percentage offset_percentage\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 non_offset_percentage = 30;
int offset_percentage = 50;
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] == "-density" && argidx+2 < args.size()) {
non_offset_percentage = atoi(args[++argidx].c_str());
offset_percentage = atoi(args[++argidx].c_str());
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;
@ -163,8 +181,7 @@ struct Pmux2ShiftxPass : public Pass {
if (seldb.empty())
continue;
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);
bool printed_pmux_header = false;
SigSpec updated_S = cell->getPort("\\S");
SigSpec updated_B = cell->getPort("\\B");
@ -180,17 +197,40 @@ struct Pmux2ShiftxPass : public Pass {
sig = it.first;
}
log(" checking ctrl signal %s\n", log_signal(sig));
// 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));
@ -329,7 +369,7 @@ struct Pmux2ShiftxPass : public Pass {
// check density percentages
Const offset(State::S0, GetSize(sig));
if (absolute_density < non_offset_percentage && range_density >= offset_percentage)
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));
@ -342,7 +382,7 @@ struct Pmux2ShiftxPass : public Pass {
new_perm_choices[const_sub(it.first, offset, false, false, GetSize(sig))] = it.second;
perm_choices.swap(new_perm_choices);
} else
if (absolute_density < non_offset_percentage) {
if (absolute_density < min_non_offset_percentage) {
log(" insufficient density.\n");
seldb.erase(sig);
continue;

2
tests/various/pmux2shiftx.ys
View file

@ -2,7 +2,7 @@ read_verilog pmux2shiftx.v
prep
design -save gold
pmux2shiftx -density 70 50
pmux2shiftx -min_density 70 50
opt