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/*
* yosys -- Yosys Open SYnthesis Suite
*
* Copyright (C) 2012 Claire Xenia Wolf <claire@yosyshq.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/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
static bool can_use_fully_defined_pool(RTLIL::SwitchRule *sw)
{
if (!GetSize(sw->signal))
return false;
for (const RTLIL::SigBit &bit : sw->signal)
if (bit.wire == NULL)
return false;
for (const RTLIL::CaseRule *cas : sw->cases)
for (const RTLIL::SigSpec &sig : cas->compare)
if (!sig.is_fully_def())
return false;
return true;
}
// This replicates the necessary parts of BitPatternPool's interface, but rather
// than storing remaining patterns, this explicitly stores which fully-defined
// constants have already been matched.
struct FullyDefinedPool
{
FullyDefinedPool(const RTLIL::SigSpec &signal)
: max_patterns{signal.size() >= 32 ? 0ul : 1ul << signal.size()}
{}
bool take(RTLIL::SigSpec sig)
{
if (default_reached || patterns.count(sig))
return false;
patterns.insert(sig);
return true;
}
void take_all()
{
default_reached = true;
}
bool empty()
{
return default_reached ||
(max_patterns && max_patterns == patterns.size());
}
pool<RTLIL::SigSpec> patterns;
bool default_reached = false;
size_t max_patterns;
};
void proc_rmdead(RTLIL::SwitchRule *sw, int &counter, int &full_case_counter);
template <class Pool>
static void proc_rmdead_impl(RTLIL::SwitchRule *sw, int &counter, int &full_case_counter)
{
Pool 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, full_case_counter);
if (is_default)
pool.take_all();
}
if (pool.empty() && !sw->get_bool_attribute(ID::full_case)) {
sw->set_bool_attribute(ID::full_case);
full_case_counter++;
}
}
void proc_rmdead(RTLIL::SwitchRule *sw, int &counter, int &full_case_counter)
{
if (can_use_fully_defined_pool(sw))
proc_rmdead_impl<FullyDefinedPool>(sw, counter, full_case_counter);
else
proc_rmdead_impl<BitPatternPool>(sw, counter, full_case_counter);
}
struct ProcRmdeadPass : public Pass {
ProcRmdeadPass() : Pass("proc_rmdead", "eliminate dead trees in decision trees") { }
void help() override
{
// |---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");
}
void execute(std::vector<std::string> args, RTLIL::Design *design) override
{
log_header(design, "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, full_case_counter = 0;
for (auto switch_it : proc_it.second->root_case.switches)
proc_rmdead(switch_it, counter, full_case_counter);
if (counter > 0)
log("Removed %d dead cases from process %s in module %s.\n", counter,
log_id(proc_it.first), log_id(mod));
if (full_case_counter > 0)
log("Marked %d switch rules as full_case in process %s in module %s.\n",
full_case_counter, log_id(proc_it.first), log_id(mod));
total_counter += counter;
}
}
log("Removed a total of %d dead cases.\n", total_counter);
}
} ProcRmdeadPass;
PRIVATE_NAMESPACE_END
|
