BFEarlyBypass.cc

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/**
 * @file BFEarlyBypass.cc
 *
 * Definition of BFEarlyBypass class
 *
 * Performs a bypass before scheduling an (operand) move
 *
 * @author Heikki Kultala 2014-2020(heikki.kultala-no.spam-tuni.fi)
 * @note rating: red
 */
 
#include "BFEarlyBypass.hh"
#include "BFDREEarly.hh"
#include "MachineConnectivityCheck.hh"
#include "DataDependenceGraph.hh"
#include "BF2Scheduler.hh"
#include "BF2ScheduleFront.hh"
#include "Machine.hh"
#include "BFMergeAndKeepUser.hh"
 
//#define DEBUG_BUBBLEFISH_SCHEDULER
//#define DEBUG_LOOP_SCHEDULER
#ifdef DEBUG_BUBBLEFISH_SCHEDULER
#define DEBUG_LOOP_SCHEDULER
#endif
 
bool
BFEarlyBypass::operator()() {
 
#ifdef DEBUG_LOOP_SCHEDULER
    if (ii() != 0) {
        std::cerr << "\t\t\tEarly bypass for: " << src_.toString()
                  << " to " << dst_.toString() << std::endl;
    }
#endif
    // Take the predecssors so that they can be notified because their
    // antideps may change
    DataDependenceGraph::NodeSet pred = ddg().predecessors(dst_);
 
    assert(!dst_.isScheduled());
    if (!runPreChild(new BFMergeAndKeepUser(sched_, src_, dst_))) {
        return false;
    }
 
    // if alwayswriteresults, then must have exactly one result write.
    if (targetMachine().alwaysWriteResults()) {
        // if destination is variable, we have two variable writes. MUST DRE.
        if (dst_.isDestinationVariable()) {
            BFDREEarly* dre = new BFDREEarly(sched_,src_);
            if (!runPostChild(dre)) {
                undo();
                return false;
            }
        }
        // if destination is not variable, must NOT DRE.
    } else {
        BFDREEarly* dre = new BFDREEarly(sched_,src_);
        runPostChild(dre);
    }
    sched_.currentFront()->bypassed(src_, dst_);
#ifdef DEBUG_BUBBLEFISH_SCHEDULER
    std::cerr << "\t\tEarly bypass ok for: " << dst_.toString() << std::endl;
#endif
 
    // now notify antideps sources
    for (auto i : pred) {
        mightBeReady(*i);
    }
 
    return true;
}
 
void
BFEarlyBypass::undoOnlyMe() {
    sched_.currentFront()->undidBypass(src_, dst_);
}