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package org.graalvm.compiler.nodes;

import static org.graalvm.compiler.nodeinfo.InputType.Association;
import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_0;
import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_0;

import java.util.List;

import org.graalvm.compiler.debug.DebugCloseable;
import org.graalvm.compiler.graph.IterableNodeType;
import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.graph.NodeInputList;
import org.graalvm.compiler.graph.iterators.NodeIterable;
import org.graalvm.compiler.graph.spi.Simplifiable;
import org.graalvm.compiler.graph.spi.SimplifierTool;
import org.graalvm.compiler.nodeinfo.NodeInfo;
import org.graalvm.compiler.nodes.StructuredGraph.FrameStateVerificationFeature;
import org.graalvm.compiler.nodes.memory.MemoryPhiNode;
import org.graalvm.compiler.nodes.spi.LIRLowerable;
import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;
import org.graalvm.compiler.nodes.util.GraphUtil;

Denotes the merging of multiple control-flow paths.
/** * Denotes the merging of multiple control-flow paths. */
@NodeInfo(allowedUsageTypes = Association, cycles = CYCLES_0, size = SIZE_0) public abstract class AbstractMergeNode extends BeginStateSplitNode implements IterableNodeType, Simplifiable, LIRLowerable { public static final NodeClass<AbstractMergeNode> TYPE = NodeClass.create(AbstractMergeNode.class); protected AbstractMergeNode(NodeClass<? extends AbstractMergeNode> c) { super(c); } @Input(Association) protected NodeInputList<EndNode> ends = new NodeInputList<>(this); @Override public void generate(NodeLIRBuilderTool gen) { gen.visitMerge(this); } public int forwardEndIndex(EndNode end) { return ends.indexOf(end); } public void addForwardEnd(EndNode end) { ends.add(end); } public final int forwardEndCount() { return ends.size(); } public final EndNode forwardEndAt(int index) { return ends.get(index); } @Override public NodeIterable<EndNode> cfgPredecessors() { return ends; }
Determines if a given node is a phi whose merge is this node.
Params:
  • value – the instruction to test
Returns:true if value is a phi and its merge is this
/** * Determines if a given node is a phi whose {@linkplain PhiNode#merge() merge} is this node. * * @param value the instruction to test * @return {@code true} if {@code value} is a phi and its merge is {@code this} */
public boolean isPhiAtMerge(Node value) { return value instanceof PhiNode && ((PhiNode) value).merge() == this; }
Removes the given end from the merge, along with the entries corresponding to this end in the phis connected to the merge.
Params:
  • pred – the end to remove
/** * Removes the given end from the merge, along with the entries corresponding to this end in the * phis connected to the merge. * * @param pred the end to remove */
public void removeEnd(AbstractEndNode pred) { int predIndex = phiPredecessorIndex(pred); assert predIndex != -1; deleteEnd(pred); for (PhiNode phi : phis().snapshot()) { if (phi.isDeleted()) { continue; } ValueNode removedValue = phi.valueAt(predIndex); phi.removeInput(predIndex); if (removedValue != null) { GraphUtil.tryKillUnused(removedValue); } } } protected void deleteEnd(AbstractEndNode end) { ends.remove(end); } public void clearEnds() { ends.clear(); } public NodeInputList<EndNode> forwardEnds() { return ends; } public int phiPredecessorCount() { return forwardEndCount(); } public int phiPredecessorIndex(AbstractEndNode pred) { return forwardEndIndex((EndNode) pred); } public AbstractEndNode phiPredecessorAt(int index) { return forwardEndAt(index); } public NodeIterable<PhiNode> phis() { return this.usages().filter(PhiNode.class).filter(this::isPhiAtMerge); } public NodeIterable<ValuePhiNode> valuePhis() { return this.usages().filter(ValuePhiNode.class); } public NodeIterable<MemoryPhiNode> memoryPhis() { return this.usages().filter(MemoryPhiNode.class); } @Override public NodeIterable<Node> anchored() { return super.anchored().filter(n -> !isPhiAtMerge(n)); }
This simplify method can deal with a null value for tool, so that it can be used outside of canonicalization.
/** * This simplify method can deal with a null value for tool, so that it can be used outside of * canonicalization. */
@Override @SuppressWarnings("try") public void simplify(SimplifierTool tool) { FixedNode currentNext = next(); if (currentNext instanceof AbstractEndNode) { AbstractEndNode origLoopEnd = (AbstractEndNode) currentNext; AbstractMergeNode merge = origLoopEnd.merge(); if (merge instanceof LoopBeginNode && !(origLoopEnd instanceof LoopEndNode)) { return; } // in order to move anchored values to the other merge we would need to check if the // anchors are used by phis of the other merge if (this.anchored().isNotEmpty()) { return; } if (merge.stateAfter() == null && this.stateAfter() != null) { // We hold a state, but the succeeding merge does not => do not combine. return; } for (PhiNode phi : phis()) { for (Node usage : phi.usages()) { if (!(usage instanceof VirtualState) && !merge.isPhiAtMerge(usage)) { return; } } } getDebug().log("Split %s into ends for %s.", this, merge); int numEnds = this.forwardEndCount(); for (int i = 0; i < numEnds - 1; i++) { AbstractEndNode end = forwardEndAt(numEnds - 1 - i); if (tool != null) { tool.addToWorkList(end); } AbstractEndNode newEnd; try (DebugCloseable position = end.withNodeSourcePosition()) { if (merge instanceof LoopBeginNode) { newEnd = graph().add(new LoopEndNode((LoopBeginNode) merge)); } else { EndNode tmpEnd = graph().add(new EndNode()); merge.addForwardEnd(tmpEnd); newEnd = tmpEnd; } } for (PhiNode phi : merge.phis()) { ValueNode v = phi.valueAt(origLoopEnd); ValueNode newInput; if (isPhiAtMerge(v)) { PhiNode endPhi = (PhiNode) v; newInput = endPhi.valueAt(end); } else { newInput = v; } phi.addInput(newInput); } this.removeEnd(end); end.replaceAtPredecessor(newEnd); end.safeDelete(); if (tool != null) { tool.addToWorkList(newEnd.predecessor()); } } graph().reduceTrivialMerge(this); } else if (currentNext instanceof ReturnNode) { ReturnNode returnNode = (ReturnNode) currentNext; if (anchored().isNotEmpty() || returnNode.getMemoryMap() != null) { return; } List<PhiNode> phis = phis().snapshot(); for (PhiNode phi : phis) { for (Node usage : phi.usages()) { if (usage != returnNode && !(usage instanceof FrameState)) { return; } } } ValuePhiNode returnValuePhi = returnNode.result() == null || !isPhiAtMerge(returnNode.result()) ? null : (ValuePhiNode) returnNode.result(); List<EndNode> endNodes = forwardEnds().snapshot(); for (EndNode end : endNodes) { try (DebugCloseable position = returnNode.withNodeSourcePosition()) { ReturnNode newReturn = graph().add(new ReturnNode(returnValuePhi == null ? returnNode.result() : returnValuePhi.valueAt(end))); if (tool != null) { tool.addToWorkList(end.predecessor()); } end.replaceAtPredecessor(newReturn); } } GraphUtil.killCFG(this); for (EndNode end : endNodes) { end.safeDelete(); } for (PhiNode phi : phis) { if (tool.allUsagesAvailable() && phi.isAlive() && phi.hasNoUsages()) { GraphUtil.killWithUnusedFloatingInputs(phi); } } } } protected boolean verifyState() { return this.stateAfter != null; } @Override public boolean verify() { assert !this.graph().getFrameStateVerification().implies(FrameStateVerificationFeature.MERGES) || verifyState() : "Merge must have a state until FSA " + this; return super.verify(); } }