Example #1
0
  /**
   * Reverse if-convert a block. Return a new hyperblock starting with the reverse if-converted
   * block or null.
   */
  private Hyperblock reverseIfConvertBlock(PredicateBlock block) {
    int rp = block.getPredicate();
    boolean sense = block.isPredicatedOnTrue();

    // Insert a label at the beginning of the block.

    TripsLabel lab = (TripsLabel) gen.createLabel();
    gen.updateLabelIndex(lab);
    block.insertInstructionAtHead(lab);

    // Insert a branch to this block in its predecessors.

    for (int i = block.numInEdges() - 1; i > -1; i--) {
      PredicateBlock pred = (PredicateBlock) block.getInEdge(i);
      int rpPred = pred.getPredicate();
      boolean sensePred = pred.isPredicatedOnTrue();
      boolean needThunk = true;

      // Check if we need a thunk.

      if (!block.isPredicated()) {
        needThunk = false;
      } else if (pred.numOutEdges() == 1) {
        needThunk = false;
      } else if ((rp == rpPred) && (sense == sensePred)) {
        needThunk = false;
      }

      // Create a branch to the label and insert it.

      if (needThunk) {
        TripsBranch br = new TripsBranch(Opcodes.BRO, lab, 1, rp, sense);
        PredicateBlock thunk = new PredicateBlock(rp, sense);

        br.addTarget(lab, 0);
        thunk.appendInstruction(br);
        pred.addOutEdge(thunk);
        thunk.addInEdge(pred);
      } else {
        TripsBranch br = new TripsBranch(Opcodes.BRO, lab, 1, rpPred, sensePred);

        br.addTarget(lab, 0);
        pred.appendInstruction(br);
      }

      pred.deleteOutEdge(block);
      block.deleteInEdge(pred);
    }

    blocksReverseIfConvertedCount++;

    // Create the new hyperblock.

    BitVect predicates = removePredicates(block);
    Hyperblock hnew = new Hyperblock(block, predicates, regs);

    hnew.updateLastBlock();

    return hnew;
  }
Example #2
0
  /** Reverse if-convert the given predicate block from the hyperblock. */
  private void reverseIfConvert(Hyperblock hb, PredicateBlock start) {
    Stack<Node> wl = WorkArea.<Node>getStack("reverseIfConvert");
    Stack<PredicateBlock> reverse = WorkArea.<PredicateBlock>getStack("reverseIfConvert");
    Vector<PredicateBlock> blocks = new Vector<PredicateBlock>();
    Vector<Hyperblock> hbs = new Vector<Hyperblock>();

    // Find the blocks which need to be reverse if-converted.

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

    while (!wl.isEmpty()) {
      PredicateBlock block = (PredicateBlock) wl.pop();
      block.pushOutEdges(wl);

      for (int i = 0; i < block.numInEdges(); i++) {
        PredicateBlock pred = (PredicateBlock) block.getInEdge(i);
        if (!pred.visited()) {
          blocks.add(block);
          break;
        } else if (blocks.contains(pred) && block.numInEdges() > 1) {
          blocks.add(block);
          break;
        }
      }
    }

    // Order the blocks to reverse if-convert based on their depth from the root.

    PredicateBlock head = hb.getFirstBlock();
    Vector<PredicateBlock> wl2 = new Vector<PredicateBlock>();

    head.nextVisit();
    head.setVisited();
    wl2.add(head);

    while (!wl2.isEmpty()) {
      int l = wl2.size();

      for (int i = 0; i < l; i++) {
        PredicateBlock block = wl2.get(i);
        if (blocks.contains(block)) {
          blocks.remove(block);
          reverse.push(block);
        }
      }

      wl2 = hb.getNextPFGLevel(wl2);
    }

    // Remove the special "dummy" last block from the PFG.

    PredicateBlock last = hb.getLastBlock();
    assert (last.numOutEdges() == 0 && !last.isPredicated());

    if (last.getFirstInstruction() == null) {
      for (int i = last.numInEdges() - 1; i > -1; i--) {
        PredicateBlock pred = (PredicateBlock) last.getInEdge(i);
        pred.deleteOutEdge(last);
        last.deleteInEdge(pred);
      }
      reverse.remove(last);
    }

    // Reverse if-convert.

    while (!reverse.isEmpty()) {
      PredicateBlock block = reverse.pop();
      Hyperblock hbn = reverseIfConvertBlock(block);

      hbs.add(hbn);
      workingSet.add(hbn);
    }

    // Update the PFG.

    hb.updateLastBlock();
    hb.invalidateDomination(); // The dominators are now invalid.

    // Insert the new hyperblocks in the HFG.

    HashMap<Instruction, Hyperblock> entries = computeEntries(hb, hbs);
    hbs.add(hb);
    Hyperblock.computeHyperblockFlowGraph(hbs, entries);

    // Update the return block.  Since 'hbs' is an ordered list, the
    // first element in the list is the hyperblock with the return
    // because this was the original tail of the PFG which was reverse
    // if-converted.

    if (hb == gen.getReturnBlock()) {
      gen.setReturnBlock(hbs.firstElement());
    }

    WorkArea.<Node>returnStack(wl);
    WorkArea.<PredicateBlock>returnStack(reverse);
  }
Example #3
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);
  }