yosys/passes/cmds/scc.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.
*
*/
// [[CITE]] Tarjan's strongly connected components algorithm
// Tarjan, R. E. (1972), "Depth-first search and linear graph algorithms", SIAM Journal on Computing 1 (2): 146160, doi:10.1137/0201010
// http://en.wikipedia.org/wiki/Tarjan's_strongly_connected_components_algorithm
#include "kernel/register.h"
#include "kernel/celltypes.h"
#include "kernel/sigtools.h"
#include "kernel/log.h"
#include <stdlib.h>
#include <stdio.h>
#include <set>
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
struct SccWorker
{
RTLIL::Design *design;
RTLIL::Module *module;
SigMap sigmap;
CellTypes ct;
std::set<RTLIL::Cell*> workQueue;
std::map<RTLIL::Cell*, std::set<RTLIL::Cell*>> cellToNextCell;
std::map<RTLIL::Cell*, RTLIL::SigSpec> cellToPrevSig, cellToNextSig;
std::map<RTLIL::Cell*, std::pair<int, int>> cellLabels;
std::map<RTLIL::Cell*, int> cellDepth;
std::set<RTLIL::Cell*> cellsOnStack;
std::vector<RTLIL::Cell*> cellStack;
int labelCounter;
std::map<RTLIL::Cell*, int> cell2scc;
std::vector<std::set<RTLIL::Cell*>> sccList;
void run(RTLIL::Cell *cell, int depth, int maxDepth)
{
log_assert(workQueue.count(cell) > 0);
workQueue.erase(cell);
cellLabels[cell] = std::pair<int, int>(labelCounter, labelCounter);
labelCounter++;
cellsOnStack.insert(cell);
cellStack.push_back(cell);
if (maxDepth >= 0)
cellDepth[cell] = depth;
for (auto nextCell : cellToNextCell[cell])
if (cellLabels.count(nextCell) == 0) {
run(nextCell, depth+1, maxDepth);
cellLabels[cell].second = std::min(cellLabels[cell].second, cellLabels[nextCell].second);
} else
if (cellsOnStack.count(nextCell) > 0 && (maxDepth < 0 || cellDepth[nextCell] + maxDepth > depth)) {
cellLabels[cell].second = std::min(cellLabels[cell].second, cellLabels[nextCell].second);
}
if (cellLabels[cell].first == cellLabels[cell].second)
{
if (cellStack.back() == cell)
{
cellStack.pop_back();
cellsOnStack.erase(cell);
}
else
{
log("Found an SCC:");
std::set<RTLIL::Cell*> scc;
while (cellsOnStack.count(cell) > 0) {
RTLIL::Cell *c = cellStack.back();
cellStack.pop_back();
cellsOnStack.erase(c);
log(" %s", RTLIL::id2cstr(c->name));
cell2scc[c] = sccList.size();
scc.insert(c);
}
sccList.push_back(scc);
log("\n");
}
}
}
SccWorker(RTLIL::Design *design, RTLIL::Module *module, bool nofeedbackMode, bool allCellTypes, int maxDepth) :
design(design), module(module), sigmap(module)
{
if (module->processes.size() > 0) {
log("Skipping module %s as it contains processes (run 'proc' pass first).\n", module->name.c_str());
return;
}
if (allCellTypes) {
ct.setup(design);
} else {
ct.setup_internals();
ct.setup_stdcells();
}
SigPool selectedSignals;
SigSet<RTLIL::Cell*> sigToNextCells;
for (auto &it : module->wires_)
if (design->selected(module, it.second))
selectedSignals.add(sigmap(RTLIL::SigSpec(it.second)));
for (auto &it : module->cells_)
{
RTLIL::Cell *cell = it.second;
if (!design->selected(module, cell))
continue;
if (!allCellTypes && !ct.cell_known(cell->type))
continue;
workQueue.insert(cell);
RTLIL::SigSpec inputSignals, outputSignals;
for (auto &conn : cell->connections())
{
bool isInput = true, isOutput = true;
if (ct.cell_known(cell->type)) {
isInput = ct.cell_input(cell->type, conn.first);
isOutput = ct.cell_output(cell->type, conn.first);
}
RTLIL::SigSpec sig = selectedSignals.extract(sigmap(conn.second));
sig.sort_and_unify();
if (isInput)
inputSignals.append(sig);
if (isOutput)
outputSignals.append(sig);
}
inputSignals.sort_and_unify();
outputSignals.sort_and_unify();
cellToPrevSig[cell] = inputSignals;
cellToNextSig[cell] = outputSignals;
sigToNextCells.insert(inputSignals, cell);
}
for (auto cell : workQueue)
cellToNextCell[cell] = sigToNextCells.find(cellToNextSig[cell]);
labelCounter = 0;
cellLabels.clear();
while (workQueue.size() > 0)
{
RTLIL::Cell *cell = *workQueue.begin();
log_assert(cellStack.size() == 0);
cellDepth.clear();
if (!nofeedbackMode && cellToNextCell[cell].count(cell)) {
log("Found an SCC:");
std::set<RTLIL::Cell*> scc;
log(" %s", RTLIL::id2cstr(cell->name));
cell2scc[cell] = sccList.size();
scc.insert(cell);
sccList.push_back(scc);
workQueue.erase(cell);
log("\n");
} else
run(cell, 0, maxDepth);
}
log("Found %d SCCs in module %s.\n", int(sccList.size()), RTLIL::id2cstr(module->name));
}
void select(RTLIL::Selection &sel)
{
for (int i = 0; i < int(sccList.size()); i++)
{
std::set<RTLIL::Cell*> &cells = sccList[i];
RTLIL::SigSpec prevsig, nextsig, sig;
for (auto cell : cells) {
sel.selected_members[module->name].insert(cell->name);
prevsig.append(cellToPrevSig[cell]);
nextsig.append(cellToNextSig[cell]);
}
prevsig.sort_and_unify();
nextsig.sort_and_unify();
sig = prevsig.extract(nextsig);
for (auto &chunk : sig.chunks())
if (chunk.wire != NULL)
sel.selected_members[module->name].insert(chunk.wire->name);
}
}
};
struct SccPass : public Pass {
SccPass() : Pass("scc", "detect strongly connected components (logic loops)") { }
virtual void help()
{
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
log("\n");
log(" scc [options] [selection]\n");
log("\n");
log("This command identifies strongly connected components (aka logic loops) in the\n");
log("design.\n");
log("\n");
log(" -expect <num>\n");
log(" expect to find exactly <num> SSCs. A different number of SSCs will\n");
log(" produce an error.\n");
log("\n");
log(" -max_depth <num>\n");
log(" limit to loops not longer than the specified number of cells. This\n");
log(" can e.g. be useful in identifying small local loops in a module that\n");
log(" implements one large SCC.\n");
log("\n");
log(" -nofeedback\n");
log(" do not count cells that have their output fed back into one of their\n");
log(" inputs as single-cell scc.\n");
log("\n");
log(" -all_cell_types\n");
log(" Usually this command only considers internal non-memory cells. With\n");
log(" this option set, all cells are considered. For unknown cells all ports\n");
log(" are assumed to be bidirectional 'inout' ports.\n");
log("\n");
log(" -set_attr <name> <value>\n");
log(" -set_cell_attr <name> <value>\n");
log(" -set_wire_attr <name> <value>\n");
log(" set the specified attribute on all cells and/or wires that are part of\n");
log(" a logic loop. the special token {} in the value is replaced with a\n");
log(" unique identifier for the logic loop.\n");
log("\n");
log(" -select\n");
log(" replace the current selection with a selection of all cells and wires\n");
log(" that are part of a found logic loop\n");
log("\n");
}
virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
{
std::map<std::string, std::string> setCellAttr, setWireAttr;
bool allCellTypes = false;
bool selectMode = false;
bool nofeedbackMode = false;
int maxDepth = -1;
int expect = -1;
log_header("Executing SCC pass (detecting logic loops).\n");
size_t argidx;
for (argidx = 1; argidx < args.size(); argidx++) {
if (args[argidx] == "-max_depth" && argidx+1 < args.size()) {
maxDepth = atoi(args[++argidx].c_str());
continue;
}
if (args[argidx] == "-expect" && argidx+1 < args.size()) {
expect = atoi(args[++argidx].c_str());
continue;
}
if (args[argidx] == "-nofeedback") {
nofeedbackMode = true;
continue;
}
if (args[argidx] == "-all_cell_types") {
allCellTypes = true;
continue;
}
if (args[argidx] == "-set_attr" && argidx+2 < args.size()) {
setCellAttr[args[argidx+1]] = args[argidx+2];
setWireAttr[args[argidx+1]] = args[argidx+2];
argidx += 2;
continue;
}
if (args[argidx] == "-set_cell_attr" && argidx+2 < args.size()) {
setCellAttr[args[argidx+1]] = args[argidx+2];
argidx += 2;
continue;
}
if (args[argidx] == "-set_wire_attr" && argidx+2 < args.size()) {
setWireAttr[args[argidx+1]] = args[argidx+2];
argidx += 2;
continue;
}
if (args[argidx] == "-select") {
selectMode = true;
continue;
}
break;
}
int origSelectPos = design->selection_stack.size() - 1;
extra_args(args, argidx, design);
if (setCellAttr.size() > 0 || setWireAttr.size() > 0)
log_cmd_error("The -set*_attr options are not implemented at the moment!\n");
RTLIL::Selection newSelection(false);
int scc_counter = 0;
for (auto &mod_it : design->modules_)
if (design->selected(mod_it.second))
{
SccWorker worker(design, mod_it.second, nofeedbackMode, allCellTypes, maxDepth);
scc_counter += GetSize(worker.sccList);
if (selectMode)
worker.select(newSelection);
}
if (expect >= 0) {
if (scc_counter == expect)
log("Found and expected %d SCCs.\n", scc_counter);
else
log_error("Found %d SCCs but expected %d.\n", scc_counter, expect);
} else
log("Found %d SCCs.\n", scc_counter);
if (selectMode) {
log_assert(origSelectPos >= 0);
design->selection_stack[origSelectPos] = newSelection;
design->selection_stack[origSelectPos].optimize(design);
}
}
} SccPass;
PRIVATE_NAMESPACE_END