BFDRELate.cc

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/**
 * @file BFDRELate.cc
 *
 * Definition of BFDRELate class
 *
 * Performs a dead-result elimination after a late bypass.
 *
 * @author Heikki Kultala 2014-2020(heikki.kultala-no.spam-tuni.fi)
 * @note rating: red
 */
 
#include "BFDRELate.hh"
#include "DataDependenceGraph.hh"
#include "BF2Scheduler.hh"
#include "Machine.hh"
 
bool
BFDRELate::operator()() {
    if (!sched_.killDeadResults() && !targetMachine().alwaysWriteResults()) {
        return false;
    }
 
    if (!ddg().resultUsed(mn_)) {
 
        // Take the predecssors of the dre'd src because their
        // antideps may change
         DataDependenceGraph::NodeSet pred = ddg().predecessors(mn_);
 
         createdEdges_ =  ddg().copyDepsOver(mn_, true, false);
        assert(!mn_.isScheduled());
        ddg().dropNode(mn_);
        sched_.nodeAndCopyKilled(mn_);
 
        // now mark antideps sources to be notified
        for (auto n: pred) {
            mightBeReady(*n);
        }
 
#ifdef DEBUG_BUBBLEFISH_SCHEDULER
    std::cerr << "\t\t\tLate DRE ok: " << mn_.toString() << std::endl;
#endif
        return true;
    } else {
        return false;
    }
}