verilator/src/V3Hashed.cpp

// -*- mode: C++; c-file-style: "cc-mode" -*-
//*************************************************************************
// DESCRIPTION: Verilator: Hashed common code into functions
//
// Code available from: https://verilator.org
//
//*************************************************************************
//
// Copyright 2003-2020 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
//
//*************************************************************************
// V3Hashed's Transformations:
//
//          Hash each node depth first
//              Hash includes varp name and operator type, and constants
//              Form lookup table based on hash of each statement  w/ nodep and next nodep
//
//*************************************************************************

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

#include "V3Global.h"
#include "V3Hashed.h"
#include "V3Ast.h"
#include "V3File.h"

#include <algorithm>
#include <iomanip>
#include <map>
#include <memory>

//######################################################################
// Hashed state, as a visitor of each AstNode

class HashedVisitor final : public AstNVisitor {
private:
    // NODE STATE
    // Entire netlist:
    //  AstNodeStmt::user4()    -> V3Hash.  Hash value of this node (hash of 0 is illegal)
    // AstUser4InUse     in V3Hashed.h

    // STATE
    V3Hash m_lowerHash;  // Hash of the statement we're building
    bool m_cacheInUser4;  // Use user4 to cache each V3Hash?

    // METHODS
    VL_DEBUG_FUNC;  // Declare debug()

    void nodeHashIterate(AstNode* nodep) {
        V3Hash thisHash;
        if (!m_cacheInUser4 || !nodep->user4()) {
            UASSERT_OBJ(
                !(VN_IS(nodep->backp(), CFunc)
                  && !(VN_IS(nodep, NodeStmt) || VN_IS(nodep, CFunc))),
                nodep,
                "Node " << nodep->prettyTypeName()
                        << " in statement position but not marked stmt (node under function)");
            VL_RESTORER(m_lowerHash);
            {
                m_lowerHash = nodep->sameHash();
                UASSERT_OBJ(!m_lowerHash.isIllegal(), nodep,
                            "sameHash function undefined (returns 0) for node under CFunc.");
                // For identical nodes, the type should be the same thus
                // dtypep should be the same too
                m_lowerHash
                    = V3Hash(m_lowerHash, V3Hash(nodep->type() << 6, V3Hash(nodep->dtypep())));
                // Now update m_lowerHash for our children's (and next children) contributions
                iterateChildren(nodep);
                // Store the hash value
                nodep->user4(m_lowerHash.fullValue());
                // UINFO(9, "    hashnode "<<m_lowerHash<<"  "<<nodep<<endl);
                thisHash = m_lowerHash;
            }
        }
        // Update what will become the above node's hash
        m_lowerHash += m_cacheInUser4 ? V3Hashed::nodeHash(nodep) : thisHash;
    }

    //--------------------
    virtual void visit(AstVar*) override {}
    virtual void visit(AstTypedef*) override {}
    virtual void visit(AstParamTypeDType*) override {}
    virtual void visit(AstNode* nodep) override {
        // Hash not just iterate
        nodeHashIterate(nodep);
    }

public:
    // CONSTRUCTORS
    explicit HashedVisitor(AstNode* nodep)
        : m_cacheInUser4{true} {
        nodeHashIterate(nodep);
        // UINFO(9,"  stmthash "<<hex<<V3Hashed::nodeHash(nodep)<<"  "<<nodep<<endl);
    }
    explicit HashedVisitor(const AstNode* nodep)
        : m_cacheInUser4{false} {
        nodeHashIterate(const_cast<AstNode*>(nodep));
    }
    V3Hash finalHash() const { return m_lowerHash; }
    virtual ~HashedVisitor() override = default;
};

//######################################################################
// Hashed class functions

V3Hash V3Hashed::uncachedHash(const AstNode* nodep) {
    HashedVisitor visitor(nodep);
    return visitor.finalHash();
}

V3Hashed::iterator V3Hashed::hashAndInsert(AstNode* nodep) {
    hash(nodep);
    return m_hashMmap.insert(make_pair(nodeHash(nodep), nodep));
}

void V3Hashed::hash(AstNode* nodep) {
    UINFO(8, "   hashI " << nodep << endl);
    if (!nodep->user4p()) { HashedVisitor visitor(nodep); }
}

bool V3Hashed::sameNodes(AstNode* node1p, AstNode* node2p) {
    UASSERT_OBJ(node1p->user4p(), node1p, "Called isIdentical on non-hashed nodes");
    UASSERT_OBJ(node2p->user4p(), node2p, "Called isIdentical on non-hashed nodes");
    return (node1p->user4p() == node2p->user4p()  // Same hash
            && node1p->sameTree(node2p));
}

void V3Hashed::erase(iterator it) {
    AstNode* nodep = iteratorNodep(it);
    UINFO(8, "   erase " << nodep << endl);
    UASSERT_OBJ(nodep->user4p(), nodep, "Called removeNode on non-hashed node");
    m_hashMmap.erase(it);
    nodep->user4p(nullptr);  // So we don't allow removeNode again
}

void V3Hashed::check() {
    for (const auto& itr : *this) {
        AstNode* nodep = itr.second;
        UASSERT_OBJ(nodep->user4p(), nodep, "V3Hashed check failed, non-hashed node");
    }
}

void V3Hashed::dumpFilePrefixed(const string& nameComment, bool tree) {
    if (v3Global.opt.dumpTree()) dumpFile(v3Global.debugFilename(nameComment) + ".hash", tree);
}

void V3Hashed::dumpFile(const string& filename, bool tree) {
    const std::unique_ptr<std::ofstream> logp(V3File::new_ofstream(filename));
    if (logp->fail()) v3fatal("Can't write " << filename);

    std::unordered_map<int, int> dist;

    V3Hash lasthash;
    int num_in_bucket = 0;
    for (HashMmap::iterator it = begin(); true; ++it) {
        if (it == end() || lasthash != it->first) {
            if (it != end()) lasthash = it->first;
            if (num_in_bucket) {
                if (dist.find(num_in_bucket) == dist.end()) {
                    dist.insert(make_pair(num_in_bucket, 1));
                } else {
                    ++dist[num_in_bucket];
                }
            }
            num_in_bucket = 0;
        }
        if (it == end()) break;
        num_in_bucket++;
    }
    *logp << "\n*** STATS:\n\n";
    *logp << "    #InBucket   Occurrences\n";
    for (const auto& i : dist) {
        *logp << "    " << std::setw(9) << i.first << "  " << std::setw(12) << i.second << '\n';
    }

    *logp << "\n*** Dump:\n\n";
    for (const auto& itr : *this) {
        if (lasthash != itr.first) {
            lasthash = itr.first;
            *logp << "    " << itr.first << '\n';
        }
        *logp << "\t" << itr.second << '\n';
        // Dumping the entire tree may make nearly N^2 sized dumps,
        // because the nodes under this one may also be in the hash table!
        if (tree) itr.second->dumpTree(*logp, "    ");
    }
}

V3Hashed::iterator V3Hashed::findDuplicate(AstNode* nodep, V3HashedUserSame* checkp) {
    UINFO(8, "   findD " << nodep << endl);
    UASSERT_OBJ(nodep->user4p(), nodep, "Called findDuplicate on non-hashed node");
    std::pair<HashMmap::iterator, HashMmap::iterator> eqrange
        = mmap().equal_range(nodeHash(nodep));
    for (HashMmap::iterator eqit = eqrange.first; eqit != eqrange.second; ++eqit) {
        AstNode* node2p = eqit->second;
        if (nodep != node2p && (!checkp || checkp->isSame(nodep, node2p))
            && sameNodes(nodep, node2p)) {
            return eqit;
        }
    }
    return end();
}