LiveRangeData.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 LiveRangeData.cc
 *
 * Implementation of LiveRangeData class.
 *
 * Contains live range-related data for one basic block.
 * This is geenrated and used by ddg builder.
 * This may also be used by later parts of the scheduler.
 *
 * @author Heikki Kultala 2011 (hkultala@cs.tut.fi)
 * @note rating: red
 */
 
#include "LiveRangeData.hh"
#include "DataDependenceGraph.hh"
#include "Move.hh"
 
/**
 * merges liverangedata of successor into this.
 *
 * @param succ later basic block which is merged into this one.
 */
void LiveRangeData::merge(LiveRangeData& succ) {
 
    // copy outgoing live information as it is from successor
    appendUseMapSets(succ.regDefines_, regDefines_, false);
    appendUseMapSets(succ.regLastUses_, regLastUses_, false);
 
    // after this BB alive regs are those that are alive after the latter bb.
    registersUsedAfter_ = succ.registersUsedAfter_;
 
    // then in incoming deps, merge from both.
 
    appendUseMapSets(succ.regFirstDefines_, regFirstDefines_, false);
    appendUseMapSets(succ.regFirstUses_, regFirstUses_, false);
    appendUseMapSets(succ.regDefReaches_ , regDefReaches_, false);
 
}
 
/**
 * This appends the data from one MoveNodeUseMapSet to another.
 *
 * it traverses the map, and for every string, set pair it
 * finds or creates the corresponging set in the destination and appends
 * the set to that set.
 * This is used for copying alive definitions.
 *
 * @param srcMap source where to copy from
 * @param dstMap destination where to copy to.
 * @param addLoopProperty whether to add loop property to the copied
 *        bookkeeping, ie create edges with loop property.
 * @return true if destination changed (needs updating)
 */
bool
LiveRangeData::appendUseMapSets(
    const MoveNodeUseMapSet& srcMap, MoveNodeUseMapSet& dstMap,
    bool addLoopProperty) {
    bool changed = false;
    for (MoveNodeUseMapSet::const_iterator srcIter = srcMap.begin();
         srcIter != srcMap.end(); srcIter++) {
        TCEString reg = srcIter->first;
        const MoveNodeUseSet& srcSet = srcIter->second;
        MoveNodeUseSet& dstSet = dstMap[reg];
        // dest set size before appending.
        size_t size = dstSet.size();
        appendMoveNodeUse(srcSet, dstSet, addLoopProperty);
        // if size has changed, dest is changed.
        if (dstSet.size() > size) {
            changed = true;
        }
    }
    return changed;
}
 
/**
 * Appends a MoveNodeUseSet to another. May set loop property of copied
 * moves to true.
 *
 * @param src source set
 * @param dst destination set
 * @param setLoopProperty whether to set loop property true in copied data
 */
void LiveRangeData::appendMoveNodeUse(
    const LiveRangeData::MoveNodeUseSet& src, 
    LiveRangeData::MoveNodeUseSet& dst,
    bool setLoopProperty) {
 
    for (LiveRangeData::MoveNodeUseSet::const_iterator i =
             src.begin(); i != src.end(); i++) {
        const MoveNodeUse& mnu = *i;
        if (setLoopProperty || mnu.loop()) {
            dst.insert(MoveNodeUse(mnu, MoveNodeUse::LOOP));
        } else {
            dst.insert(MoveNodeUse(mnu, MoveNodeUse::INTRA_BB));
        }
    }
}
 
/**
 * Returns the set of registers that are alive at the given cycle.
 */
std::set<TCEString> 
LiveRangeData::registersAlive(
    int cycle, int delaySlots, DataDependenceGraph& ddg) {
 
    std::set<TCEString> aliveRegs;
 
    // Part 1: Live ranges incoming to this BB.
    // handles both incoming and overgoing live ranges
    for (MoveNodeUseMapSet::iterator rdrIter = regDefReaches_.begin();
         rdrIter != regDefReaches_.end(); rdrIter++) {
        const TCEString& reg = rdrIter->first;
 
        // if use after and not killed here, alive for the whole BB.
        if (registersUsedAfter_.find(reg) != registersUsedAfter_.end()) {
            // nothing in this BB overwrites this.
            if (regKills_.find(reg) == regKills_.end()) {
                aliveRegs.insert(reg);
            }
        }
 
        // check for first uses in this BB. If before a read, is used.
        MoveNodeUseSet& firstUses = regFirstUses_[reg];
        for (MoveNodeUseSet::iterator iter = firstUses.begin();
             iter != firstUses.end(); iter++) {
            const MoveNode& mn = *(iter->mn());
            if (mn.isScheduled()) {
                int mnCycle = mn.cycle();
                if (iter->pseudo()) {
                    mnCycle += delaySlots;
                }
                if (cycle <= mnCycle) {
                    aliveRegs.insert(reg);
                }
            } else { // unscheduled.. later?
                aliveRegs.insert(reg);
            }
        }
    }
 
    // Part 2: check deps going out from this.
    for (std::set<TCEString>::iterator ruaIter = registersUsedAfter_.begin();
         ruaIter != registersUsedAfter_.end(); ruaIter++) {
        const TCEString& reg = *ruaIter;
 
        // check against last defines.
        MoveNodeUseSet& lastDefs = regDefines_[reg];
        for (MoveNodeUseSet::iterator iter = lastDefs.begin();
             iter != lastDefs.end(); iter++) {
            const MoveNode& mn = *iter->mn();
            if (mn.isScheduled()) {
                int mnCycle = mn.cycle();
                if (iter->pseudo()) {
                    mnCycle += delaySlots;
                }
                if (cycle >= mnCycle) {
                    aliveRegs.insert(reg);
                }
            }
            // if not scheduld, is at end?
        }
    }
 
    // part 3: Check edges inside this BB. done from DDG.
 
    // TODO: psedo-dep delay slots.
    for (int i = 0; i < ddg.nodeCount(); i++) {
        MoveNode& node = ddg.node(i);
        // only check writes that are scheduled.
        if (!node.isScheduled() || node.cycle() > cycle) {
            continue; // write after the given cycle
        }
 
        // Find all edges out from this
        DataDependenceGraph::EdgeSet edges = ddg.outEdges(node);
        for (DataDependenceGraph::EdgeSet::iterator eIter = 
                 edges.begin(); eIter != edges.end(); eIter++) {
            DataDependenceEdge& edge = **eIter;
 
            // we are only interested in register RAWs.
            if ((edge.edgeReason() == DataDependenceEdge::EDGE_REGISTER || 
                 edge.edgeReason() == DataDependenceEdge::EDGE_RA) &&
                (edge.dependenceType() == DataDependenceEdge::DEP_RAW)) {
                const TCEString& reg = edge.data();
                MoveNode &headNode = ddg.headNode(edge);
                // if tail pseudo, delay by delaySlots amount
                if (edge.tailPseudo()) {
                    if (node.cycle() + delaySlots > cycle) {
                        continue;
                    }
                }
                // if pseudo, delay mncycle by delayslot amount
                int delay = edge.headPseudo() ? delaySlots : 0;
                // is the read after this
                if (headNode.isScheduled() && 
                    headNode.cycle()+delay >= cycle) {
                    aliveRegs.insert(reg);
                }
            }
        }
    }
    return aliveRegs;
}