예제 #1
0
  /** Split a hyperblock. */
  private void splitHyperblock(Hyperblock hb) {
    PredicateBlock block = (hb.numSpills() > 0) ? findSplitPointSpills(hb) : findSplitPoint(hb);

    if (block.isPredicated()) {
      reverseIfConvert(hb, block);
      return;
    }

    int bsize = block.getBlockSize() + block.getFanout() + block.getSpillSize();
    if (bsize > Trips2Machine.maxBlockSize) {
      splitBlock(hb, block);
      return;
    }

    if (block.maxLSID() >= Trips2Machine.maxLSQEntries) {
      splitBlock(hb, block);
      return;
    }

    if (block.numInEdges() == 0) {
      splitBlock(hb, block);
      return;
    }

    reverseIfConvert(hb, block);
  }
예제 #2
0
  /** Find the predicate block in a hyperblock to split. */
  private PredicateBlock findSplitPoint(Hyperblock hb) {
    Vector<PredicateBlock> wl = new Vector<PredicateBlock>();

    int totalSize = hb.getFanout() + hb.getBlockSize();
    int splits = (totalSize / Trips2Machine.maxBlockSize) + 1;
    int splitSize = totalSize / splits;
    int hbSize = 0;
    PredicateBlock start = hb.getFirstBlock();
    PredicateBlock lastUnpredicated = null;
    int lastUnpredicatedHBSize = 0;

    assert (hb.numSpills() == 0) : "This method should not be called for blocks with spills.";

    start.nextVisit();
    start.setVisited();
    wl.add(start);

    while (!wl.isEmpty()) {
      int l = wl.size();
      int levelSize = 0;
      int levelLSID = 0;

      // Compute the statistics for this level of the PFG.

      for (int i = 0; i < l; i++) {
        PredicateBlock block = wl.get(i);
        int blockSize = block.getBlockSize() + block.getFanout();
        int id = block.maxLSID();

        levelSize += blockSize;
        if (id > levelLSID) {
          levelLSID = id;
        }

        // Remember the block and the hyperblock size if this block is unpredicated
        // and not the special exit block.
        // TODO - Can we remove the restriction on being the last block now?

        if (!block.isPredicated()) {
          if (block.numOutEdges() > 0) {
            if (lastUnpredicatedHBSize < (blockSize + hbSize)) {
              lastUnpredicatedHBSize = blockSize + hbSize;
              lastUnpredicated = block;
            }
          }
        }
      }

      // Determine if all the blocks can be added to the hyperblock.

      int size = hbSize + levelSize;
      if ((size > Trips2Machine.maxBlockSize) || (levelLSID >= Trips2Machine.maxLSQEntries)) {
        break;
      }

      hbSize = size;
      wl = hb.getNextPFGLevel(wl);
    }

    assert (!wl.isEmpty()) : "This block does not need to be split?";

    // If there is only one unpredicated block in the level and it is
    // not the special exit block use it.  Or if this is the only
    // block in the PFG.

    int l = wl.size();
    if (l == 1) {
      PredicateBlock block = wl.get(0);
      if (!block.isPredicated()) {
        if ((start == block) || (block.numOutEdges() > 0)) {
          // System.out.println("block");
          return block;
        }
      }
    }

    // Is there a last known unpredicated block of adequate size use it.

    if (lastUnpredicated != null) {
      if (lastUnpredicatedHBSize >= splitSize) {
        // System.out.println("*** last unpred is greater than split sz " + splitSize);
        return lastUnpredicated;
      }
    }

    // Try to find a parent that's unpredicated unless the parent is
    // the first block.

    for (int i = 0; i < l; i++) {
      PredicateBlock block = wl.get(i);
      int pl = block.numInEdges();
      for (int j = 0; j < pl; j++) {
        PredicateBlock pred = (PredicateBlock) block.getInEdge(j);
        if (!pred.isPredicated() && pred.numInEdges() > 1) {
          // System.out.println("unpred parent not start");
          return pred;
        }
      }
    }

    // Reverse if-convert the largest block in this level which is not
    // an exit.  Although this seems like a good idea, there is not
    // always enough room in the hyperblock to fanout the live-outs to
    // the write instructions.  Don't do this for now. -- Aaron

    PredicateBlock candidate = null;
    int largest = 0;
    //     for (int i = 0; i < l; i++) {
    //       PredicateBlock block = (PredicateBlock) wl.get(i);
    //       int            bsize = block.getBlockSize() + block.getFanout() + block.getSpillSize();
    //       if ((bsize > largest) && (block.numBranches() == 0)) {
    //         largest   = bsize;
    //         candidate = block;
    //       }
    //     }

    //     if (candidate != null) {
    //       //System.out.println("level no exit");
    //       return candidate;
    //     }

    // Reverse if-convert a parent which is not start.
    // Prefer parents that are split points.

    for (int i = 0; i < l; i++) {
      PredicateBlock block = wl.get(i);
      int pl = block.numInEdges();
      for (int j = 0; j < pl; j++) {
        PredicateBlock pred = (PredicateBlock) block.getInEdge(j);
        if (pred != start) {
          if (pred.isSplitPoint()) {
            // System.out.println("pred out isSplit not start");
            return pred;
          }
          candidate = pred;
        }
      }
    }

    if (candidate != null) {
      // System.out.println("pred out not start");
      return candidate;
    }

    // Reverse if-convert the largest successor of start without an exit.

    largest = 0;
    for (int i = 0; i < start.numOutEdges(); i++) {
      PredicateBlock block = (PredicateBlock) start.getOutEdge(i);
      int bsize = block.getBlockSize() + block.getFanout() + block.getSpillSize();
      if ((bsize > largest) && !block.hasBranch()) {
        largest = bsize;
        candidate = block;
      }
    }

    if (candidate != null) {
      // System.out.println("start successor no exit");
      return candidate;
    }

    // System.out.println("1st start successor ?");
    return (PredicateBlock) start.getOutEdge(0);
  }