BFPushAntidepsDown.cc

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/**
 * @file BFPushAntidepsDown.cc
 *
 * Definition of BFPushAntidepsDown class.
 *
 * Checks antidep successors of a move and tries to reschedule the limiting ones
 * to later cycle b calling BFPushAntidepDown for it.
 *
 * @author Heikki Kultala 2014-2020(heikki.kultala-no.spam-tuni.fi)
 * @note rating: red
 */
 
#include "BFPushAntidepsDown.hh"
#include "BFPushAntidepDown.hh"
 
#include <list>
 
#include "DataDependenceGraph.hh"
 
//#include "DataDependenceGraph.hh"
 
bool BFPushAntidepsDown::operator()() {
 
    DataDependenceGraph::EdgeSet outEdges = ddg().outEdges(adepSource_);
    int newLC = maxLC_;
 
    std::list<BFPushAntidepDown*> rescheds;
 
    for (auto e: outEdges) {
        if ((e->edgeReason() == DataDependenceEdge::EDGE_REGISTER ||
             e->edgeReason() == DataDependenceEdge::EDGE_RA) &&
            e->isFalseDep()) {
            MoveNode& aDepHead = ddg().headNode(*e);
            if (!aDepHead.isScheduled()) {
                continue;
            }
            int cycle = aDepHead.cycle();
            int lat = 1;
            if (e->guardUse()) {
                lat = adepSource_.guardLatency();
            }
            if (cycle + lat > maxLC_) {
                continue;
            }
            int dstLC = ddg().latestCycle(aDepHead);
#ifdef DEBUG_BUBBLEFISH_SCHEDULER
            std::cerr << "\t\tShould rescheduling move at: "
                      << aDepHead.toString() << std::endl;
            std::cerr << "\t\tdstLC: " << dstLC << std::endl;
#endif
            if (dstLC > aDepHead.cycle()) {
                rescheds.push_back(
                    new BFPushAntidepDown(sched_, aDepHead, lat, newLC));
            }
 
 
            int curLC = dstLC - lat + 1;
            if (curLC < newLC) {
                newLC = curLC;
            }
        }
    }
    // can we improve the situation at all?
    if (newLC <= oldLC_) {
#ifdef DEBUG_BUBBLEFISH_SCHEDULER
        std::cerr << "newLC: " << newLC << " old LC: " << oldLC_ << std::endl;
#endif
        for (std::list<BFPushAntidepDown*>::iterator i = rescheds.begin();
             i != rescheds.end();) {
            BFPushAntidepDown* bfo = *i;
            delete bfo;
            rescheds.erase(i++);
        }
//  assert(rescheds.empty());
        return false;
    } else {
#ifdef DEBUG_BUBBLEFISH_SCHEDULER
        std::cerr << "\t\t\tCould improve? newLC: " << newLC << std::endl;
#endif
    }
 
    for (auto i = rescheds.begin(); i != rescheds.end();) {
        BFPushAntidepDown* bfo = *i;
        rescheds.erase(i++);
        runPostChild(bfo);
    }
    return !postChildren_.empty();
}