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The GraalVM compiler and the Graal-truffle optimizer.
/*
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*
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* accompanied this code).
*
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package jdk.graal.compiler.phases.graph;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;
import java.util.List;
import java.util.function.Predicate;
import org.graalvm.collections.EconomicMap;
import org.graalvm.collections.Equivalence;
import jdk.graal.compiler.core.common.cfg.Loop;
import jdk.graal.compiler.core.common.util.CompilationAlarm;
import jdk.graal.compiler.debug.Assertions;
import jdk.graal.compiler.nodes.AbstractEndNode;
import jdk.graal.compiler.nodes.AbstractMergeNode;
import jdk.graal.compiler.nodes.FixedNode;
import jdk.graal.compiler.nodes.LoopBeginNode;
import jdk.graal.compiler.nodes.cfg.ControlFlowGraph;
import jdk.graal.compiler.nodes.cfg.HIRBlock;
public final class ReentrantBlockIterator {
public static class LoopInfo {
public final List endStates;
public final List exitStates;
public LoopInfo(int endCount, int exitCount) {
endStates = new ArrayList<>(endCount);
exitStates = new ArrayList<>(exitCount);
}
}
/**
* Abstract base class for reverse post order iteration over the {@link ControlFlowGraph}.
*/
public abstract static class BlockIteratorClosure {
/**
* Create the initial state for the reverse post order iteration over the
* {@link ControlFlowGraph}.
*/
protected abstract StateT getInitialState();
/**
* Process the current block with the current state during reverse post order iteration.
*/
protected abstract StateT processBlock(HIRBlock block, StateT currentState);
/**
* Merge multiple states when processing {@link HIRBlock} starting with a
* {@link AbstractMergeNode}.
*/
protected abstract StateT merge(HIRBlock merge, List states);
/**
* Clone a state for a successor invocation of
* {@link BlockIteratorClosure#processBlock(HIRBlock, Object)}.
*/
protected abstract StateT cloneState(StateT oldState);
/**
* Hook for subclasses to apply additional operations after
* {@link BlockIteratorClosure#cloneState(Object)} for successor blocks.
*/
protected StateT afterSplit(@SuppressWarnings("unused") HIRBlock successor, StateT oldState) {
return oldState;
}
protected List processLoop(Loop loop, StateT initialState) {
return ReentrantBlockIterator.processLoop(this, loop, initialState).exitStates;
}
}
private ReentrantBlockIterator() {
// no instances allowed
}
public static LoopInfo processLoop(BlockIteratorClosure closure, Loop loop, StateT initialState) {
EconomicMap blockEndStates = apply(closure, loop.getHeader(), initialState, block -> !(block.getLoop() == loop || block.isLoopHeader()));
HIRBlock lh = loop.getHeader();
final int predCount = lh.getPredecessorCount();
LoopInfo info = new LoopInfo<>(predCount - 1, loop.getLoopExits().size());
for (int i = 1; i < predCount; i++) {
StateT endState = blockEndStates.get(lh.getPredecessorAt(i).getEndNode());
// make sure all end states are unique objects
info.endStates.add(closure.cloneState(endState));
}
for (HIRBlock loopExit : loop.getLoopExits()) {
assert loopExit.getPredecessorCount() == 1 : Assertions.errorMessage(loop, loopExit);
assert blockEndStates.containsKey(loopExit.getBeginNode()) : loopExit.getBeginNode() + " " + blockEndStates;
StateT exitState = blockEndStates.get(loopExit.getBeginNode());
// make sure all exit states are unique objects
info.exitStates.add(closure.cloneState(exitState));
}
return info;
}
public static void apply(BlockIteratorClosure closure, HIRBlock start) {
apply(closure, start, closure.getInitialState(), null);
}
public static EconomicMap apply(BlockIteratorClosure closure, HIRBlock start, StateT initialState, Predicate stopAtBlock) {
Deque blockQueue = new ArrayDeque<>();
/*
* States are stored on EndNodes before merges, and on BeginNodes after ControlSplitNodes.
*/
EconomicMap states = EconomicMap.create(Equivalence.IDENTITY);
StateT state = initialState;
HIRBlock current = start;
CompilationAlarm compilationAlarm = CompilationAlarm.current();
while (true) { // TERMINATION ARGUMENT: processing all blocks reverse post order until end
// of cfg or until a bailout is triggered because of a long compile
CompilationAlarm.checkProgress(start.getCfg().graph);
compilationAlarm.checkExpiration();
HIRBlock next = null;
if (stopAtBlock != null && stopAtBlock.test(current)) {
states.put(current.getBeginNode(), state);
} else {
state = closure.processBlock(current, state);
if (current.getSuccessorCount() == 0) {
// nothing to do...
} else if (current.getSuccessorCount() == 1) {
HIRBlock successor = current.getSuccessorAt(0);
if (successor.isLoopHeader()) {
if (current.isLoopEnd()) {
// nothing to do... loop ends only lead to loop begins we've already
// visited
states.put(current.getEndNode(), state);
} else {
recurseIntoLoop(closure, blockQueue, states, state, successor);
}
} else if (current.getEndNode() instanceof AbstractEndNode) {
AbstractEndNode end = (AbstractEndNode) current.getEndNode();
// add the end node and see if the merge is ready for processing
AbstractMergeNode merge = end.merge();
if (allEndsVisited(states, current, merge)) {
ArrayList mergedStates = mergeStates(states, state, current, successor, merge);
state = closure.merge(successor, mergedStates);
next = successor;
} else {
assert !states.containsKey(end);
states.put(end, state);
}
} else {
next = successor;
}
} else {
next = processMultipleSuccessors(closure, blockQueue, states, state, current);
}
}
// get next queued block
if (next != null) {
current = next;
} else if (blockQueue.isEmpty()) {
return states;
} else {
current = blockQueue.removeFirst();
assert current.getPredecessorCount() == 1 : Assertions.errorMessage(current);
assert states.containsKey(current.getBeginNode());
state = states.removeKey(current.getBeginNode());
}
}
}
private static boolean allEndsVisited(EconomicMap states, HIRBlock current, AbstractMergeNode merge) {
for (AbstractEndNode forwardEnd : merge.forwardEnds()) {
if (forwardEnd != current.getEndNode() && !states.containsKey(forwardEnd)) {
return false;
}
}
return true;
}
private static HIRBlock processMultipleSuccessors(BlockIteratorClosure closure, Deque blockQueue, EconomicMap states, StateT state,
HIRBlock current) {
assert current.getSuccessorCount() > 1 : Assertions.errorMessageContext("current", current);
for (int i = 1; i < current.getSuccessorCount(); i++) {
HIRBlock successor = current.getSuccessorAt(i);
blockQueue.addFirst(successor);
states.put(successor.getBeginNode(), closure.afterSplit(successor, closure.cloneState(state)));
}
return current.getSuccessorAt(0);
}
private static ArrayList mergeStates(EconomicMap states, StateT state, HIRBlock current, HIRBlock successor, AbstractMergeNode merge) {
ArrayList mergedStates = new ArrayList<>(merge.forwardEndCount());
for (int i = 0; i < successor.getPredecessorCount(); i++) {
HIRBlock predecessor = successor.getPredecessorAt(i);
assert predecessor == current || states.containsKey(predecessor.getEndNode());
StateT endState = predecessor == current ? state : states.removeKey(predecessor.getEndNode());
mergedStates.add(endState);
}
return mergedStates;
}
private static void recurseIntoLoop(BlockIteratorClosure closure, Deque blockQueue, EconomicMap states, StateT state, HIRBlock successor) {
// recurse into the loop
Loop loop = successor.getLoop();
LoopBeginNode loopBegin = (LoopBeginNode) loop.getHeader().getBeginNode();
assert successor.getBeginNode() == loopBegin : Assertions.errorMessage(successor, successor.getBeginNode(), loopBegin);
List exitStates = closure.processLoop(loop, state);
int i = 0;
assert loop.getLoopExits().size() == exitStates.size() : Assertions.errorMessage(loop, loop.getLoopExits(), exitStates);
for (HIRBlock exit : loop.getLoopExits()) {
states.put(exit.getBeginNode(), exitStates.get(i++));
blockQueue.addFirst(exit);
}
}
}