proc_clean.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/log.h"
#include <stdlib.h>
#include <stdio.h>

YOSYS_NAMESPACE_BEGIN
extern void proc_clean_case(RTLIL::CaseRule *cs, bool &did_something, int &count, int max_depth);
YOSYS_NAMESPACE_END

USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN

void proc_clean_switch(RTLIL::SwitchRule *sw, RTLIL::CaseRule *parent, bool &did_something, int &count, int max_depth)
{
    if (sw->signal.size() > 0 && sw->signal.is_fully_const())
    {
        int found_matching_case_idx = -1;
        for (int i = 0; i < int(sw->cases.size()) && found_matching_case_idx < 0; i++)
        {
            RTLIL::CaseRule *cs = sw->cases[i];
            if (cs->compare.size() == 0)
                break;
            for (int j = 0; j < int(cs->compare.size()); j++) {
                RTLIL::SigSpec &val = cs->compare[j];
                if (!val.is_fully_const())
                    continue;
                if (val == sw->signal) {
                    cs->compare.clear();
                    found_matching_case_idx = i;
                    break;
                } else
                    cs->compare.erase(cs->compare.begin()+(j--));
            }
            if (cs->compare.size() == 0 && found_matching_case_idx < 0) {
                sw->cases.erase(sw->cases.begin()+(i--));
                delete cs;
            }
        }
        while (found_matching_case_idx >= 0 && int(sw->cases.size()) > found_matching_case_idx+1) {
            delete sw->cases.back();
            sw->cases.pop_back();
        }
        if (found_matching_case_idx == 0)
            sw->signal = RTLIL::SigSpec();
    }

    if (parent->switches.front() == sw && sw->cases.size() == 1 &&
            (sw->signal.size() == 0 || sw->cases[0]->compare.empty()))
    {
        did_something = true;
        for (auto &action : sw->cases[0]->actions)
            parent->actions.push_back(action);
        for (auto sw2 : sw->cases[0]->switches)
            parent->switches.push_back(sw2);
        sw->cases[0]->switches.clear();
        delete sw->cases[0];
        sw->cases.clear();
    }
    else
    {
        bool all_cases_are_empty = true;
        for (auto cs : sw->cases) {
            if (cs->actions.size() != 0 || cs->switches.size() != 0)
                all_cases_are_empty = false;
            if (max_depth != 0)
                proc_clean_case(cs, did_something, count, max_depth-1);
        }
        if (all_cases_are_empty) {
            did_something = true;
            for (auto cs : sw->cases)
                delete cs;
            sw->cases.clear();
        }
    }
}

PRIVATE_NAMESPACE_END
YOSYS_NAMESPACE_BEGIN

void proc_clean_case(RTLIL::CaseRule *cs, bool &did_something, int &count, int max_depth)
{
    for (size_t i = 0; i < cs->actions.size(); i++) {
        if (cs->actions[i].first.size() == 0) {
            did_something = true;
            cs->actions.erase(cs->actions.begin() + (i--));
        }
    }
    for (size_t i = 0; i < cs->switches.size(); i++) {
        RTLIL::SwitchRule *sw = cs->switches[i];
        if (sw->cases.size() == 0) {
            cs->switches.erase(cs->switches.begin() + (i--));
            did_something = true;
            delete sw;
            count++;
        } else if (max_depth != 0)
            proc_clean_switch(sw, cs, did_something, count, max_depth-1);
    }
}

YOSYS_NAMESPACE_END
PRIVATE_NAMESPACE_BEGIN

void proc_clean(RTLIL::Module *mod, RTLIL::Process *proc, int &total_count)
{
    int count = 0;
    bool did_something = true;
    for (size_t i = 0; i < proc->syncs.size(); i++) {
        for (size_t j = 0; j < proc->syncs[i]->actions.size(); j++)
            if (proc->syncs[i]->actions[j].first.size() == 0)
                proc->syncs[i]->actions.erase(proc->syncs[i]->actions.begin() + (j--));
        if (proc->syncs[i]->actions.size() == 0) {
            delete proc->syncs[i];
            proc->syncs.erase(proc->syncs.begin() + (i--));
        }
    }
    while (did_something) {
        did_something = false;
        proc_clean_case(&proc->root_case, did_something, count, -1);
    }
    if (count > 0)
        log("Found and cleaned up %d empty switch%s in `%s.%s'.\n", count, count == 1 ? "" : "es", mod->name.c_str(), proc->name.c_str());
    total_count += count;
}

struct ProcCleanPass : public Pass {
    ProcCleanPass() : Pass("proc_clean", "remove empty parts of processes") { }
    virtual void help()
    {
        //   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
        log("\n");
        log("    proc_clean [selection]\n");
        log("\n");
        log("This pass removes empty parts of processes and ultimately removes a process\n");
        log("if it contains only empty structures.\n");
        log("\n");
    }
    virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
    {
        int total_count = 0;
        log_header("Executing PROC_CLEAN pass (remove empty switches from decision trees).\n");

        extra_args(args, 1, design);

        for (auto mod : design->modules()) {
            std::vector<RTLIL::IdString> delme;
            if (!design->selected(mod))
                continue;
            for (auto &proc_it : mod->processes) {
                if (!design->selected(mod, proc_it.second))
                    continue;
                proc_clean(mod, proc_it.second, total_count);
                if (proc_it.second->syncs.size() == 0 && proc_it.second->root_case.switches.size() == 0 &&
                        proc_it.second->root_case.actions.size() == 0) {
                    log("Removing empty process `%s.%s'.\n", log_id(mod), proc_it.second->name.c_str());
                    delme.push_back(proc_it.first);
                }
            }
            for (auto &id : delme) {
                delete mod->processes[id];
                mod->processes.erase(id);
            }
        }

        log("Cleaned up %d empty switch%s.\n", total_count, total_count == 1 ? "" : "es");
    }
} ProcCleanPass;
 
PRIVATE_NAMESPACE_END