verilator/src/V3SenTree.h

// -*- mode: C++; c-file-style: "cc-mode" -*-
//*************************************************************************
// DESCRIPTION: Verilator: Break always into sensitivity block domains
//
// Code available from: https://verilator.org
//
//*************************************************************************
//
// Copyright 2003-2022 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
//
//*************************************************************************
// AstSenTree related utilities.
//*************************************************************************

#ifndef VERILATOR_V3SENTREE_H_
#define VERILATOR_V3SENTREE_H_

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

#include "V3Ast.h"
#include "V3Hasher.h"

#include <unordered_set>

//######################################################################
// Collect SenTrees under the entire scope
// And provide functions to find/add a new one

class SenTreeSet final {
    // Hash table of sensitive blocks.
private:
    // TYPES
    struct HashSenTree {
        size_t operator()(const AstSenTree* kp) const {
            return V3Hasher::uncachedHash(kp).value();
        }
    };

    struct EqSenTree {
        bool operator()(const AstSenTree* ap, const AstSenTree* bp) const {
            return ap->sameTree(bp);
        }
    };

    // MEMBERS
    using Set = std::unordered_set<AstSenTree*, HashSenTree, EqSenTree>;
    Set m_trees;  // Set of sensitive blocks, for folding.

public:
    // CONSTRUCTORS
    SenTreeSet() = default;

    // METHODS
    void add(AstSenTree* nodep) { m_trees.insert(nodep); }

    AstSenTree* find(AstSenTree* likep) {
        AstSenTree* resultp = nullptr;
        const auto it = m_trees.find(likep);
        if (it != m_trees.end()) resultp = *it;
        return resultp;
    }

    void clear() { m_trees.clear(); }

private:
    VL_UNCOPYABLE(SenTreeSet);
};

class SenTreeFinder final {
private:
    // STATE
    AstTopScope* const m_topScopep;  // Top scope to add global SenTrees to
    SenTreeSet m_trees;  // Set of global SenTrees

    VL_UNCOPYABLE(SenTreeFinder);

public:
    // CONSTRUCTORS
    SenTreeFinder()
        : SenTreeFinder(v3Global.rootp()) {}

    explicit SenTreeFinder(AstNetlist* netlistp)
        : m_topScopep{netlistp->topScopep()} {
        // Gather existing global SenTrees
        for (AstNode* nodep = m_topScopep->senTreesp(); nodep; nodep = nodep->nextp()) {
            m_trees.add(VN_AS(nodep, SenTree));
        }
    }

    // METHODS

    // Return a global AstSenTree that matches given SenTree.
    // If no such global AstSenTree exists create one and add it to the stored AstTopScope.
    AstSenTree* getSenTree(AstSenTree* senTreep) {
        AstSenTree* treep = m_trees.find(senTreep);
        if (!treep) {
            // Not found, form a new one
            treep = senTreep->cloneTree(false);
            m_topScopep->addSenTreep(treep);
            UINFO(8, "    New SENTREE " << treep << endl);
            m_trees.add(treep);
        }
        return treep;
    }

    // Return the global combinational AstSenTree.
    // If no such global SenTree exists create one and add it to the stored AstTopScope.
    AstSenTree* getComb() {
        FileLine* const fl = m_topScopep->fileline();
        AstSenTree* const combp = new AstSenTree{fl, new AstSenItem{fl, AstSenItem::Combo()}};
        AstSenTree* const resultp = getSenTree(combp);
        VL_DO_DANGLING(combp->deleteTree(), combp);  // getSenTree clones, so can delete
        return resultp;
    }
};

#endif  // Guard