/** 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);
}
/** 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);
}