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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/register.h"
#include "kernel/bitpattern.h"
#include "kernel/log.h"
#include <sstream>
#include <stdlib.h>
#include <stdio.h>
#include <set>
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
void proc_rmdead(RTLIL::SwitchRule *sw, int &counter)
{
BitPatternPool pool(sw->signal);
for (size_t i = 0; i < sw->cases.size(); i++)
{
bool is_default = GetSize(sw->cases[i]->compare) == 0 && (!pool.empty() || GetSize(sw->signal) == 0);
for (size_t j = 0; j < sw->cases[i]->compare.size(); j++) {
RTLIL::SigSpec sig = sw->cases[i]->compare[j];
if (!sig.is_fully_const())
continue;
if (!pool.take(sig))
sw->cases[i]->compare.erase(sw->cases[i]->compare.begin() + (j--));
}
if (!is_default) {
if (sw->cases[i]->compare.size() == 0) {
delete sw->cases[i];
sw->cases.erase(sw->cases.begin() + (i--));
counter++;
continue;
}
if (pool.empty())
sw->cases[i]->compare.clear();
}
for (auto switch_it : sw->cases[i]->switches)
proc_rmdead(switch_it, counter);
if (is_default)
pool.take_all();
}
}
struct ProcRmdeadPass : public Pass {
ProcRmdeadPass() : Pass("proc_rmdead", "eliminate dead trees in decision trees") { }
virtual void help()
{
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
log("\n");
log(" proc_rmdead [selection]\n");
log("\n");
log("This pass identifies unreachable branches in decision trees and removes them.\n");
log("\n");
}
virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
{
log_header("Executing PROC_RMDEAD pass (remove dead branches from decision trees).\n");
extra_args(args, 1, design);
int total_counter = 0;
for (auto mod : design->modules()) {
if (!design->selected(mod))
continue;
for (auto &proc_it : mod->processes) {
if (!design->selected(mod, proc_it.second))
continue;
int counter = 0;
for (auto switch_it : proc_it.second->root_case.switches)
proc_rmdead(switch_it, counter);
if (counter > 0)
log("Removed %d dead cases from process %s in module %s.\n", counter,
proc_it.first.c_str(), log_id(mod));
total_counter += counter;
}
}
log("Removed a total of %d dead cases.\n", total_counter);
}
} ProcRmdeadPass;
PRIVATE_NAMESPACE_END
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