verilator/src/V3LinkLevel.cpp

// -*- mode: C++; c-file-style: "cc-mode" -*-
//*************************************************************************
// DESCRIPTION: Verilator: Resolve module/signal name references
//
// Code available from: https://verilator.org
//
//*************************************************************************
//
// Copyright 2003-2021 by Wilson Snyder. This program is free software; you
// can redistribute it and/or modify it under the terms of either the GNU
// Lesser General Public License Version 3 or the Perl Artistic License
// Version 2.0.
// SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
//
//*************************************************************************
// LINKTOP TRANSFORMATIONS:
//      Utility functions
//          Sort cells by depth
//          Create new MODULE TOP with connections to below signals
//*************************************************************************

#include "config_build.h"
#include "verilatedos.h"

#include "V3Global.h"
#include "V3LinkLevel.h"
#include "V3Ast.h"

#include <algorithm>
#include <map>
#include <vector>

//######################################################################
// Levelizing class functions

struct CmpLevel {
    bool operator()(const AstNodeModule* lhsp, const AstNodeModule* rhsp) const {
        return lhsp->level() < rhsp->level();
    }
};

void V3LinkLevel::modSortByLevel() {
    // Sort modules by levels, root down to lowest children
    // Calculate levels again in case we added modules
    UINFO(2, "modSortByLevel()\n");

    // level() was computed for us in V3LinkCells

    ModVec mods;  // Modules
    ModVec tops;  // Top level modules
    for (AstNodeModule* nodep = v3Global.rootp()->modulesp(); nodep;
         nodep = VN_CAST(nodep->nextp(), NodeModule)) {
        if (nodep->level() <= 2) tops.push_back(nodep);
        mods.push_back(nodep);
    }
    if (tops.size() >= 2) {
        AstNode* secp = tops[1];  // Complain about second one, as first often intended
        if (!secp->fileline()->warnIsOff(V3ErrorCode::MULTITOP)) {
            secp->v3warn(MULTITOP, "Multiple top level modules\n"
                                       << secp->warnMore()
                                       << "... Suggest see manual; fix the duplicates, or use "
                                          "--top-module to select top."
                                       << V3Error::warnContextNone());
            for (AstNode* alsop : tops) {
                std::cerr << secp->warnMore() << "... Top module " << alsop->prettyNameQ() << endl
                          << alsop->warnContextSecondary();
            }
        }
    }

    timescaling(mods);

    // Reorder the netlist's modules to have modules in level sorted order
    stable_sort(mods.begin(), mods.end(), CmpLevel());  // Sort the vector
    UINFO(9, "modSortByLevel() sorted\n");  // Comment required for gcc4.6.3 / bug666
    for (AstNodeModule* nodep : mods) {
        nodep->clearIter();  // Because we didn't iterate to find the node
        // pointers, may have a stale m_iterp() needing cleanup
        nodep->unlinkFrBack();
    }
    UASSERT_OBJ(!v3Global.rootp()->modulesp(), v3Global.rootp(), "Unlink didn't work");
    for (AstNodeModule* nodep : mods) v3Global.rootp()->addModulep(nodep);
    UINFO(9, "modSortByLevel() done\n");  // Comment required for gcc4.6.3 / bug666
    V3Global::dumpCheckGlobalTree("cells", false, v3Global.opt.dumpTreeLevel(__FILE__) >= 3);
}

void V3LinkLevel::timescaling(const ModVec& mods) {
    // Timescale determination
    AstNodeModule* modTimedp = nullptr;
    VTimescale unit(VTimescale::NONE);
    // Use highest level module as default unit - already sorted in proper order
    for (const auto& modp : mods) {
        if (!modTimedp && !modp->timeunit().isNone()) {
            modTimedp = modp;
            unit = modTimedp->timeunit();
            break;
        }
    }
    unit = v3Global.opt.timeComputeUnit(unit);  // Apply override
    if (unit.isNone()) unit = VTimescale(VTimescale::TS_DEFAULT);
    v3Global.rootp()->timeunit(unit);

    bool dunitTimed = false;  // $unit had a timeunit
    if (const AstPackage* const upkgp = v3Global.rootp()->dollarUnitPkgp()) {
        if (!upkgp->timeunit().isNone()) dunitTimed = true;
    }

    for (AstNodeModule* nodep : mods) {
        if (!v3Global.opt.timeOverrideUnit().isNone()) nodep->timeunit(unit);
        if (nodep->timeunit().isNone()) {
            if (modTimedp  // Got previous
                && !dunitTimed
                && (  // unit doesn't already include an override
                    v3Global.opt.timeOverrideUnit().isNone()
                    && v3Global.opt.timeDefaultUnit().isNone())
                && nodep->timescaleMatters()) {
                nodep->v3warn(TIMESCALEMOD,
                              "Timescale missing on this module as other modules have "
                              "it (IEEE 1800-2017 3.14.2.3)\n"
                                  << nodep->warnContextPrimary() << '\n'
                                  << modTimedp->warnOther()
                                  << "... Location of module with timescale\n"
                                  << modTimedp->warnContextSecondary());
            }
            nodep->timeunit(unit);
        }
    }

    v3Global.rootp()->timescaleSpecified(modTimedp);  // true if some module specifies timescale

    if (v3Global.rootp()->timeprecision().isNone()) {
        v3Global.rootp()->timeprecisionMerge(v3Global.rootp()->fileline(),
                                             VTimescale(VTimescale::TS_DEFAULT));
    }

    // Classes under package have timescale propaged in V3LinkParse
}

//######################################################################
// Wrapping

void V3LinkLevel::wrapTop(AstNetlist* rootp) {
    UINFO(2, __FUNCTION__ << ": " << endl);
    // We do ONLY the top module
    AstNodeModule* oldmodp = rootp->modulesp();
    if (!oldmodp) {  // Later V3LinkDot will warn
        UINFO(1, "No module found to wrap\n");
        return;
    }

    AstNodeModule* newmodp = new AstModule(oldmodp->fileline(), "$root");
    newmodp->name(AstNode::encodeName(newmodp->name()));  // so origName is nice
    // Make the new module first in the list
    oldmodp->unlinkFrBackWithNext();
    newmodp->addNext(oldmodp);
    newmodp->level(1);
    newmodp->modPublic(true);
    newmodp->protect(false);
    newmodp->timeunit(oldmodp->timeunit());
    rootp->addModulep(newmodp);

    // TODO the module creation above could be done after linkcells, but
    // the rest must be done after data type resolution
    wrapTopCell(rootp);

    // Instantiate all packages under the top wrapper
    // This way all later SCOPE based optimizations can ignore packages
    for (AstNodeModule* modp = rootp->modulesp(); modp;
         modp = VN_CAST(modp->nextp(), NodeModule)) {
        if (VN_IS(modp, Package)) {
            AstCell* cellp = new AstCell(modp->fileline(), modp->fileline(),
                                         // Could add __03a__03a="::" to prevent conflict
                                         // with module names/"v"
                                         modp->name(), modp->name(), nullptr, nullptr, nullptr);
            cellp->modp(modp);
            newmodp->addStmtp(cellp);
        }
    }

    V3Global::dumpCheckGlobalTree("wraptop", 0, v3Global.opt.dumpTreeLevel(__FILE__) >= 6);
}

void V3LinkLevel::wrapTopCell(AstNetlist* rootp) {
    AstNodeModule* newmodp = rootp->modulesp();
    UASSERT_OBJ(newmodp && newmodp->isTop(), rootp, "No TOP module found to insert under");

    // Find all duplicate signal names (if multitop)
    using NameSet = std::unordered_set<std::string>;
    NameSet ioNames;
    NameSet dupNames;
    // For all modules, skipping over new top
    for (AstNodeModule* oldmodp = VN_CAST(rootp->modulesp()->nextp(), NodeModule);
         oldmodp && oldmodp->level() <= 2; oldmodp = VN_CAST(oldmodp->nextp(), NodeModule)) {
        for (AstNode* subnodep = oldmodp->stmtsp(); subnodep; subnodep = subnodep->nextp()) {
            if (AstVar* oldvarp = VN_CAST(subnodep, Var)) {
                if (oldvarp->isIO()) {
                    if (ioNames.find(oldvarp->name()) != ioNames.end()) {
                        // UINFO(8, "Multitop dup I/O found: " << oldvarp << endl);
                        dupNames.insert(oldvarp->name());
                    } else {
                        ioNames.insert(oldvarp->name());
                    }
                }
            }
        }
    }

    // For all modules, skipping over new top
    for (AstNodeModule* oldmodp = VN_CAST(rootp->modulesp()->nextp(), NodeModule);
         oldmodp && oldmodp->level() <= 2; oldmodp = VN_CAST(oldmodp->nextp(), NodeModule)) {
        if (VN_IS(oldmodp, Package)) continue;
        // Add instance
        UINFO(5, "LOOP " << oldmodp << endl);
        AstCell* cellp = new AstCell(
            newmodp->fileline(), newmodp->fileline(),
            (!v3Global.opt.l2Name().empty() ? v3Global.opt.l2Name() : oldmodp->name()),
            oldmodp->name(), nullptr, nullptr, nullptr);
        cellp->modp(oldmodp);
        newmodp->addStmtp(cellp);

        // Add pins
        for (AstNode* subnodep = oldmodp->stmtsp(); subnodep; subnodep = subnodep->nextp()) {
            if (AstVar* oldvarp = VN_CAST(subnodep, Var)) {
                UINFO(8, "VARWRAP " << oldvarp << endl);
                if (oldvarp->isIO()) {
                    string name = oldvarp->name();
                    if (dupNames.find(name) != dupNames.end()) {
                        // __02E=. while __DOT__ looks nicer but will break V3LinkDot
                        name = oldmodp->name() + "__02E" + name;
                    }

                    AstVar* varp = oldvarp->cloneTree(false);
                    varp->name(name);
                    varp->protect(false);
                    newmodp->addStmtp(varp);
                    varp->sigPublic(true);  // User needs to be able to get to it...
                    if (oldvarp->isIO()) {
                        oldvarp->primaryIO(false);
                        varp->primaryIO(true);
                    }
                    if (varp->direction().isRefOrConstRef()) {
                        varp->v3warn(E_UNSUPPORTED,
                                     "Unsupported: ref/const ref as primary input/output: "
                                         << varp->prettyNameQ());
                    }
                    if (varp->isIO() && v3Global.opt.systemC()) {
                        varp->sc(true);
                        // User can see trace one level down from the wrapper
                        // Avoids packing & unpacking SC signals a second time
                        varp->trace(false);
                    }

                    AstPin* pinp = new AstPin(
                        oldvarp->fileline(), 0, varp->name(),
                        new AstVarRef(varp->fileline(), varp,
                                      oldvarp->isWritable() ? VAccess::WRITE : VAccess::READ));
                    // Skip length and width comp; we know it's a direct assignment
                    pinp->modVarp(oldvarp);
                    cellp->addPinsp(pinp);
                }
            }
        }
    }
}