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yosys/passes/proc/proc_arst.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.
*
*/
#include "kernel/register.h"
#include "kernel/sigtools.h"
#include "kernel/log.h"
#include <stdlib.h>
#include <stdio.h>
// defined in proc_clean.cc
extern void proc_clean_case(RTLIL::CaseRule *cs, bool &did_something, int &count, int max_depth);
static bool check_signal(RTLIL::Module *mod, RTLIL::SigSpec signal, RTLIL::SigSpec ref, bool &polarity)
{
if (signal.width != 1)
return false;
if (signal == ref)
return true;
for (auto &cell_it : mod->cells) {
RTLIL::Cell *cell = cell_it.second;
if (cell->type == "$reduce_or" && cell->connections["\\Y"] == signal)
return check_signal(mod, cell->connections["\\A"], ref, polarity);
if (cell->type == "$reduce_bool" && cell->connections["\\Y"] == signal)
return check_signal(mod, cell->connections["\\A"], ref, polarity);
if (cell->type == "$logic_not" && cell->connections["\\Y"] == signal) {
polarity = !polarity;
return check_signal(mod, cell->connections["\\A"], ref, polarity);
}
if (cell->type == "$not" && cell->connections["\\Y"] == signal) {
polarity = !polarity;
return check_signal(mod, cell->connections["\\A"], ref, polarity);
}
if ((cell->type == "$eq" || cell->type == "$eqx") && cell->connections["\\Y"] == signal) {
if (cell->connections["\\A"].is_fully_const()) {
if (!cell->connections["\\A"].as_bool())
polarity = !polarity;
return check_signal(mod, cell->connections["\\B"], ref, polarity);
}
if (cell->connections["\\B"].is_fully_const()) {
if (!cell->connections["\\B"].as_bool())
polarity = !polarity;
return check_signal(mod, cell->connections["\\A"], ref, polarity);
}
}
if ((cell->type == "$ne" || cell->type == "$nex") && cell->connections["\\Y"] == signal) {
if (cell->connections["\\A"].is_fully_const()) {
if (cell->connections["\\A"].as_bool())
polarity = !polarity;
return check_signal(mod, cell->connections["\\B"], ref, polarity);
}
if (cell->connections["\\B"].is_fully_const()) {
if (cell->connections["\\B"].as_bool())
polarity = !polarity;
return check_signal(mod, cell->connections["\\A"], ref, polarity);
}
}
}
return false;
}
static void apply_const(RTLIL::Module *mod, const RTLIL::SigSpec rspec, RTLIL::SigSpec &rval, RTLIL::CaseRule *cs, RTLIL::SigSpec const_sig, bool polarity, bool unknown)
{
for (auto &action : cs->actions) {
if (unknown)
rspec.replace(action.first, RTLIL::SigSpec(RTLIL::State::Sm, action.second.width), &rval);
else
rspec.replace(action.first, action.second, &rval);
}
for (auto sw : cs->switches) {
if (sw->signal.width == 0) {
for (auto cs2 : sw->cases)
apply_const(mod, rspec, rval, cs2, const_sig, polarity, unknown);
}
bool this_polarity = polarity;
if (check_signal(mod, sw->signal, const_sig, this_polarity)) {
for (auto cs2 : sw->cases) {
for (auto comp : cs2->compare)
if (comp == RTLIL::SigSpec(this_polarity, 1))
goto matched_case;
if (cs2->compare.size() == 0) {
matched_case:
apply_const(mod, rspec, rval, cs2, const_sig, polarity, false);
break;
}
}
} else {
for (auto cs2 : sw->cases)
apply_const(mod, rspec, rval, cs2, const_sig, polarity, true);
}
}
}
static void eliminate_const(RTLIL::Module *mod, RTLIL::CaseRule *cs, RTLIL::SigSpec const_sig, bool polarity)
{
for (auto sw : cs->switches) {
bool this_polarity = polarity;
if (check_signal(mod, sw->signal, const_sig, this_polarity)) {
bool found_rem_path = false;
for (size_t i = 0; i < sw->cases.size(); i++) {
RTLIL::CaseRule *cs2 = sw->cases[i];
for (auto comp : cs2->compare)
if (comp == RTLIL::SigSpec(this_polarity, 1))
goto matched_case;
if (found_rem_path) {
matched_case:
sw->cases.erase(sw->cases.begin() + (i--));
delete cs2;
continue;
}
found_rem_path = true;
cs2->compare.clear();
}
sw->signal = RTLIL::SigSpec();
} else {
for (auto cs2 : sw->cases)
eliminate_const(mod, cs2, const_sig, polarity);
}
}
int dummy_count = 0;
bool did_something = true;
while (did_something) {
did_something = false;
proc_clean_case(cs, did_something, dummy_count, 1);
}
}
static void proc_arst(RTLIL::Module *mod, RTLIL::Process *proc, SigMap &assign_map)
{
restart_proc_arst:
if (proc->root_case.switches.size() != 1)
return;
RTLIL::SigSpec root_sig = proc->root_case.switches[0]->signal;
for (auto &sync : proc->syncs) {
if (sync->type == RTLIL::SyncType::STp || sync->type == RTLIL::SyncType::STn) {
bool polarity = sync->type == RTLIL::SyncType::STp;
if (check_signal(mod, root_sig, sync->signal, polarity)) {
if (proc->syncs.size() == 1) {
log("Found VHDL-style edge-trigger %s in `%s.%s'.\n", log_signal(sync->signal), mod->name.c_str(), proc->name.c_str());
} else {
log("Found async reset %s in `%s.%s'.\n", log_signal(sync->signal), mod->name.c_str(), proc->name.c_str());
sync->type = sync->type == RTLIL::SyncType::STp ? RTLIL::SyncType::ST1 : RTLIL::SyncType::ST0;
}
for (auto &action : sync->actions) {
RTLIL::SigSpec rspec = action.second;
RTLIL::SigSpec rval = RTLIL::SigSpec(RTLIL::State::Sm, rspec.width);
rspec.expand(), rval.expand();
for (int i = 0; i < int(rspec.chunks.size()); i++)
if (rspec.chunks[i].wire == NULL)
rval.chunks[i] = rspec.chunks[i];
rspec.optimize(), rval.optimize();
RTLIL::SigSpec last_rval;
for (int count = 0; rval != last_rval; count++) {
last_rval = rval;
apply_const(mod, rspec, rval, &proc->root_case, root_sig, polarity, false);
assign_map.apply(rval);
if (rval.is_fully_const())
break;
if (count > 100)
log_error("Async reset %s yields endless loop at value %s for signal %s.\n",
log_signal(sync->signal), log_signal(rval), log_signal(action.first));
rspec = rval;
}
if (rval.has_marked_bits())
log_error("Async reset %s yields non-constant value %s for signal %s.\n",
log_signal(sync->signal), log_signal(rval), log_signal(action.first));
action.second = rval;
}
eliminate_const(mod, &proc->root_case, root_sig, polarity);
goto restart_proc_arst;
}
}
}
}
struct ProcArstPass : public Pass {
ProcArstPass() : Pass("proc_arst", "detect asynchronous resets") { }
virtual void help()
{
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
log("\n");
log(" proc_arst [-global_arst [!]<netname>] [selection]\n");
log("\n");
log("This pass identifies asynchronous resets in the processes and converts them\n");
log("to a different internal representation that is suitable for generating\n");
log("flip-flop cells with asynchronous resets.\n");
log("\n");
log(" -global_arst [!]<netname>\n");
log(" In modules that have a net with the given name, use this net as async\n");
log(" reset for registers that have been assign initial values in their\n");
log(" declaration ('reg foobar = constant_value;'). Use the '!' modifier for\n");
log(" active low reset signals. Note: the frontend stores the default value\n");
log(" in the 'init' attribute on the net.\n");
log("\n");
}
virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
{
std::string global_arst;
bool global_arst_neg = false;
log_header("Executing PROC_ARST pass (detect async resets in processes).\n");
size_t argidx;
for (argidx = 1; argidx < args.size(); argidx++)
{
if (args[argidx] == "-global_arst" && argidx+1 < args.size()) {
global_arst = args[++argidx];
if (!global_arst.empty() && global_arst[0] == '!') {
global_arst_neg = true;
global_arst = global_arst.substr(1);
}
global_arst = RTLIL::escape_id(global_arst);
continue;
}
break;
}
extra_args(args, argidx, design);
for (auto &mod_it : design->modules)
if (design->selected(mod_it.second)) {
SigMap assign_map(mod_it.second);
for (auto &proc_it : mod_it.second->processes) {
if (!design->selected(mod_it.second, proc_it.second))
continue;
proc_arst(mod_it.second, proc_it.second, assign_map);
if (global_arst.empty() || mod_it.second->wires.count(global_arst) == 0)
continue;
std::vector<RTLIL::SigSig> arst_actions;
for (auto sync : proc_it.second->syncs)
if (sync->type == RTLIL::SyncType::STp || sync->type == RTLIL::SyncType::STn)
for (auto &act : sync->actions) {
RTLIL::SigSpec arst_sig, arst_val;
for (auto &chunk : act.first.chunks)
if (chunk.wire && chunk.wire->attributes.count("\\init")) {
RTLIL::SigSpec value = chunk.wire->attributes.at("\\init");
value.extend(chunk.wire->width, false);
arst_sig.append(chunk);
arst_val.append(value.extract(chunk.offset, chunk.width));
}
if (arst_sig.width) {
log("Added global reset to process %s: %s <- %s\n",
proc_it.first.c_str(), log_signal(arst_sig), log_signal(arst_val));
arst_actions.push_back(RTLIL::SigSig(arst_sig, arst_val));
}
}
if (!arst_actions.empty()) {
RTLIL::SyncRule *sync = new RTLIL::SyncRule;
sync->type = global_arst_neg ? RTLIL::SyncType::ST0 : RTLIL::SyncType::ST1;
sync->signal = mod_it.second->wires.at(global_arst);
sync->actions = arst_actions;
proc_it.second->syncs.push_back(sync);
}
}
}
}
} ProcArstPass;
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