private void optimizeBlock(AbstractBlock<?> block) {
if (block.getPredecessorCount() == 1) {
int nextBlock = allocator.getFirstLirInstructionId(block);
try (Scope s1 = Debug.scope("LSRAOptimization")) {
Debug.log("next block: %s (%d)", block, nextBlock);
}
try (Indent indent0 = Debug.indent()) {
walkTo(nextBlock);
try (Scope s1 = Debug.scope("LSRAOptimization")) {
boolean changed = true;
// we need to do this because the active lists might change
loop:
while (changed) {
changed = false;
try (Indent indent1 =
Debug.logAndIndent("Active intervals: (block %s [%d])", block, nextBlock)) {
for (Interval active = activeLists.get(RegisterBinding.Any);
active != Interval.EndMarker;
active = active.next) {
Debug.log("active (any): %s", active);
if (optimize(nextBlock, block, active, RegisterBinding.Any)) {
changed = true;
break loop;
}
}
for (Interval active = activeLists.get(RegisterBinding.Stack);
active != Interval.EndMarker;
active = active.next) {
Debug.log("active (stack): %s", active);
if (optimize(nextBlock, block, active, RegisterBinding.Stack)) {
changed = true;
break loop;
}
}
}
}
}
}
}
}
private boolean optimize(
int currentPos,
AbstractBlock<?> currentBlock,
Interval currentInterval,
RegisterBinding binding) {
// BEGIN initialize and sanity checks
assert currentBlock != null : "block must not be null";
assert currentInterval != null : "interval must not be null";
assert currentBlock.getPredecessorCount() == 1
: "more than one predecessors -> optimization not possible";
if (!currentInterval.isSplitChild()) {
// interval is not a split child -> no need for optimization
return false;
}
if (currentInterval.from() == currentPos) {
// the interval starts at the current position so no need for splitting
return false;
}
// get current location
AllocatableValue currentLocation = currentInterval.location();
assert currentLocation != null : "active intervals must have a location assigned!";
// get predecessor stuff
AbstractBlock<?> predecessorBlock = currentBlock.getPredecessors().get(0);
int predEndId = allocator.getLastLirInstructionId(predecessorBlock);
Interval predecessorInterval = currentInterval.getIntervalCoveringOpId(predEndId);
assert predecessorInterval != null
: "variable not live at the end of the only predecessor! "
+ predecessorBlock
+ " -> "
+ currentBlock
+ " interval: "
+ currentInterval;
AllocatableValue predecessorLocation = predecessorInterval.location();
assert predecessorLocation != null : "handled intervals must have a location assigned!";
// END initialize and sanity checks
if (currentLocation.equals(predecessorLocation)) {
// locations are already equal -> nothing to optimize
return false;
}
if (!isStackSlot(predecessorLocation) && !isRegister(predecessorLocation)) {
assert predecessorInterval.canMaterialize();
// value is materialized -> no need for optimization
return false;
}
assert isStackSlot(currentLocation) || isRegister(currentLocation)
: "current location not a register or stack slot " + currentLocation;
try (Indent indent =
Debug.logAndIndent("location differs: %s vs. %s", predecessorLocation, currentLocation)) {
// split current interval at current position
Debug.log("splitting at position %d", currentPos);
assert allocator.isBlockBegin(currentPos) && ((currentPos & 1) == 0)
: "split pos must be even when on block boundary";
Interval splitPart = currentInterval.split(currentPos, allocator);
activeLists.remove(binding, currentInterval);
assert splitPart.from() >= currentPosition
: "cannot append new interval before current walk position";
// the currentSplitChild is needed later when moves are inserted for reloading
assert splitPart.currentSplitChild() == currentInterval
: "overwriting wrong currentSplitChild";
splitPart.makeCurrentSplitChild();
if (Debug.isLogEnabled()) {
Debug.log("left interval : %s", currentInterval.logString(allocator));
Debug.log("right interval : %s", splitPart.logString(allocator));
}
if (Options.LSRAOptSplitOnly.getValue()) {
// just add the split interval to the unhandled list
unhandledLists.addToListSortedByStartAndUsePositions(RegisterBinding.Any, splitPart);
} else {
if (isRegister(predecessorLocation)) {
splitRegisterInterval(splitPart, asRegister(predecessorLocation));
} else {
assert isStackSlot(predecessorLocation);
Debug.log("assigning interval %s to %s", splitPart, predecessorLocation);
splitPart.assignLocation(predecessorLocation);
// activate interval
activeLists.addToListSortedByCurrentFromPositions(RegisterBinding.Stack, splitPart);
splitPart.state = State.Active;
splitStackInterval(splitPart);
}
}
}
return true;
}
