BUMoveNodeSelector.cc

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/*
    Copyright (c) 2002-2011 Tampere University.
 
    This file is part of TTA-Based Codesign Environment (TCE).
 
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/**
 * @file BUMoveNodeSelector.cc
 *
 * Implementation of BUMoveNodeSelector interface.
 *
 * @author Vladim’r Guzma 2011 (vladimir.guzma-no.spam-tut.fi)
 * @note rating: red
 */
 
#include "BUMoveNodeSelector.hh"
#include "DataDependenceGraph.hh"
#include "DataDependenceGraphBuilder.hh"
#include "POMDisassembler.hh"
#include "ProgramOperation.hh"
#include "Procedure.hh"
#include "BasicBlock.hh"
#include "SpecialRegisterPort.hh"
#include "Terminal.hh"
 
//#define DEBUG_OUTPUT__
//#define WRITE_DOT_SNAPSHOTS
 
//#define ABORT_ORPHAN_NODES
//#define WARN_ORPHAN_NODES
 
#ifdef ABORT_ORPHAN_NODES
#define WARN_ORPHAN_NODES
#endif
 
/**
 * Add the unscheduled sink nodes of the DDG to the ready list
 */
void
BUMoveNodeSelector::initializeReadylist() {
    while (!readyList_.empty()) {
        readyList_.pop();
    }
    DataDependenceGraph::NodeSet sinks = ddg_->sinkNodes();
    for (DataDependenceGraph::NodeSet::iterator i = sinks.begin(); 
         i != sinks.end(); 
         ++i) {
        MoveNode& node = **i;
 
        // a hack to avoid adding the root operations multiple times
        // (the count of input moves): only "announce" the move to the first
        // operand (every operation should have one input operand)
        if (node.isDestinationOperation() && !node.move().destination().isFUPort()) {
            std::cerr << "termimal not fuport even though dest op!: " << node.toString();
            ddg_->writeToDotFile("not_dest_port.dot");
        }
        if (!node.isDestinationOperation())
            mightBeReady(**i);
        else if (node.move().destination().operationIndex() == 1) {
            mightBeReady(**i); 
        }
    }
}
 
/**
 * Constructor. Creates subgraph of the given big graph
 *
 * @param bigDDG big ddg containing more than just the basic block
 * @param bb basic block for this selector.
 */
BUMoveNodeSelector::BUMoveNodeSelector(
    DataDependenceGraph& bigDDG, TTAProgram::BasicBlock& bb,
    const TTAMachine::Machine& machine)
    : ddgOwned_(true) {
    try {
        ddg_ = bigDDG.createSubgraph(bb);
        ddg_->setMachine(machine);
    } catch (InstanceNotFound& inf) {
        ModuleRunTimeError e(
            __FILE__,__LINE__,__func__,"Creation of subgraph failed");
        e.setCause(inf);
        throw e;
    }
    initializeReadylist();
}
 
/**
 * Constructor.
 *
 * @param bb The basic block from which to select moves.
 */
BUMoveNodeSelector::BUMoveNodeSelector(
    TTAProgram::BasicBlock& bb, const TTAMachine::Machine& machine) : 
    ddgOwned_(true) {    
    DataDependenceGraphBuilder ddgBuilder;
    ddg_ = ddgBuilder.build(
        bb,DataDependenceGraph::INTRA_BB_ANTIDEPS, machine);
    ddg_->setMachine(machine);
    initializeReadylist();
#if 0    
        ddg_->setCycleGrouping(true);
        ddg_->writeToDotFile("ddg.dot");    
#endif
}
 
/**
 * Constructor.
 *
 * @param ddg The data dependence graph from which to select moves.
 *            Selector does not take the ownership of the ddg.
 */
BUMoveNodeSelector::BUMoveNodeSelector(
    DataDependenceGraph& ddg, const TTAMachine::Machine& machine) : 
    ddg_(&ddg), ddgOwned_(false) {    
    ddg_->setMachine(machine);
    initializeReadylist();
}
/**
 * Destructor.
 */
BUMoveNodeSelector::~BUMoveNodeSelector() {
    if (ddgOwned_) {
        delete ddg_;
    }
}
 
/**
 * Returns DDG used internally.
 */
DataDependenceGraph&
BUMoveNodeSelector::dataDependenceGraph() {
    return *ddg_;
}
/**
 * Returns a group of move nodes which should be scheduled next.
 *
 * @return Move node group.
 */
MoveNodeGroup
BUMoveNodeSelector::candidates() {
    
    // find a MoveNodeGroup with unscheduled MoveNodes
    while (readyList_.size() > 0) {
        MoveNodeGroup moves = readyList_.top();
        if (!moves.isAlive() || moves.isScheduled() ||
            !isReadyToBeScheduled(moves))
            readyList_.pop();
        else
            return moves;
    }
    // nothing in ready list, let's see if there are "orphan" nodes
    // still to schedule
    if (ddg_->nodeCount() - ddg_->scheduledNodeCount() > 0) {
        DataDependenceGraph::NodeSet unscheduled = ddg_->unscheduledMoves();
        for (DataDependenceGraph::NodeSet::iterator i = unscheduled.begin(); 
             i != unscheduled.end();
             ++i) {
            MoveNode& node = **i;
#ifdef WARN_ORPHAN_NODES
            std::cerr << "Found orphan node: " << node.toString() << " max src dist: " 
                      << ddg_->maxSourceDistance(node) << " sink dist: " << 
                ddg_->maxSinkDistance(node) << std::endl;
            ddg_->writeToDotFile("oprhan.dot");
#ifdef ABORT_ORPHAN_NODES
            abortWithError("orphan node!");
#endif
#endif
            mightBeReady(node);
        }
    }
    
    // did we find new nodes?
    while (readyList_.size() > 0) {
        MoveNodeGroup moves = readyList_.top();
        if (moves.isScheduled())
            readyList_.pop();
        else
            return moves;
    }
    
    // return an empty move node group
    return MoveNodeGroup();
}
 
/**
 * This should be called by the client as soon as a MoveNode is scheduled
 * in order to update the internal state of the selector.
 *
 * @param node The scheduled MoveNode.
 */
void
BUMoveNodeSelector::notifyScheduled(MoveNode& node) {
 
    assert(node.isScheduled() && "Notifying scheduled even though it isn't.");
    DataDependenceGraph::NodeSet pred = ddg_->predecessors(node);
    for (DataDependenceGraph::NodeSet::iterator i = pred.begin(); 
         i != pred.end(); ++i) {
        MoveNode& predecessor = **i;
 
        // we schedule operations as entities, so if the predecessor is a
        // (operand) move, it's already in the ready list along with the
        // move itself
        if (!predecessor.inSameOperation(node))
            mightBeReady(**i);
    }
}
 
/**
 * Adds the given move node (along with the other possible move nodes in the 
 * same operation) to the ready list in case all its children in the DDG have 
 * been scheduled.
 *
 * In case the node belongs to an operation, also checks that the other 
 * result moves are also ready. In that case adds all the nodes in the said 
 * MoveOperation to the ready list in a single MoveNodeGroup. 
 *
 * @param node Move node that might be ready.
 */
void
BUMoveNodeSelector::mightBeReady(MoveNode& node) {
 
    if (node.isScheduled()) {
        return;
    }
 
    DataDependenceGraph::NodeSet queue;
    DataDependenceGraph::NodeSet nodes;
    queue.insert(&node);
 
    while (!queue.empty()) {
        MoveNode* mn = *queue.begin();
        nodes.insert(mn);
        queue.erase(mn);
        if (mn->isSourceOperation()) {
            queueOperation(mn->sourceOperation(), nodes, queue);
        }
 
        for (unsigned int i = 0; i < mn->destinationOperationCount(); i++) {
            queueOperation(mn->destinationOperation(i), nodes, queue);
        }
 
        if (mn->move().source().isUniversalMachineRegister()) {
            if (ddg_->hasNode(*mn)) {
                MoveNode* bypassSrc =
                    ddg_->onlyRegisterRawSource(*mn);
                if (bypassSrc != NULL) {
                    if (nodes.find(bypassSrc) == nodes.end()) {
                        queue.insert(bypassSrc);
                    }
                } else {
                    std::cerr << "Warning: Cannot find source for forced bypass. "
                              << " Instruction scheduler may fail/deadlock" << std::endl;
                }
            }
        }
        if (mn->move().destination().isUniversalMachineRegister()) {
            if (ddg_->hasNode(*mn)) {
                DataDependenceGraph::NodeSet rrDestinations = 
                    ddg_->onlyRegisterRawDestinations(*mn, false, false);
                for (DataDependenceGraph::NodeSet::iterator j = 
                         rrDestinations.begin(); j != rrDestinations.end(); j++) {
                    MoveNode* n = *j;
                    if (nodes.find(n) == nodes.end()) {
                        queue.insert(n);
                    }
                }
            }
        }
    }
    
    if (!isReadyToBeScheduled(nodes)) {
        return;
    }
 
 
    if (!nodes.empty()) {
        MoveNodeGroup moves(*ddg_);
        for (DataDependenceGraph::NodeSet::iterator i = nodes.begin(); i != nodes.end(); i++) {
            if (!((**i).isScheduled())) {
                moves.addNode(**i);
            }
        }
        if (moves.nodeCount()) {
            readyList_.push(moves);
        }
    }
 
}
 
/**
 * Queues all nodes of PO into queue, if they are not already in another set.
 *
 * @param po ProgramOperation whose nodes to add
 * @param nodes nodes where the final result is. if node is here, do not add
 *        to queue
 * @param queue quque where to add the nodes.
 */
void BUMoveNodeSelector::queueOperation(
    ProgramOperation& po,
    const DataDependenceGraph::NodeSet& nodes,
    DataDependenceGraph::NodeSet& queue) {
    for (int j = 0; j < po.inputMoveCount(); j++) {
        MoveNode& inputMove = po.inputMove(j);
        // only add if not already added
        if (nodes.find(&inputMove) == nodes.end()) {
            queue.insert(&inputMove);
        }
    }
 
    for (int j = 0; j < po.outputMoveCount(); j++) {
        MoveNode& outputMove = po.outputMove(j);
        // only add if not already added
        if (nodes.find(&outputMove) == nodes.end()) {
            queue.insert(&outputMove);
        }
    }
}
 
/**
 * Returns true in case the move is "data ready", that is, all its 
 * successors have been scheduled.
 *
 * It should be noted that moves within same operation are treated 
 * specially.  Additionally, as we are considering a basic block
 * at a time, the branch operation is considered always ready before 
 * all the other moves in the basic block have been scheduled.
 *
 * @param node Move to check.
 * @return True if the move is ready to be scheduled.
 */
bool
BUMoveNodeSelector::isReadyToBeScheduled(DataDependenceGraph::NodeSet& nodes) 
    const {
 
    for (DataDependenceGraph::NodeSet::iterator i = nodes.begin(); i != nodes.end(); i++) {
        MoveNode& node = **i;
        if (!isReadyToBeScheduled(node, nodes)) {
            return false;
        }
    }
    return true;
}
 
bool
BUMoveNodeSelector::isReadyToBeScheduled(MoveNode& node, DataDependenceGraph::NodeSet& nodes) 
    const {
    if (!ddg_->hasNode(node)) {
        return true;
    }
    
    return ddg_->otherSuccessorsScheduled(node, nodes);
}
 
bool
BUMoveNodeSelector::isReadyToBeScheduled(MoveNodeGroup& nodes) const {
    DataDependenceGraph::NodeSet ns;
    for (int i = 0; i < nodes.nodeCount(); i++) {
        MoveNode& mn = nodes.node(i);
        ns.insert(&mn);
    }
    return isReadyToBeScheduled(ns);
}