org.graalvm.compiler.nodes.java

Class ReachabilityFenceNode

java.lang.Object

org.graalvm.compiler.graph.Node

org.graalvm.compiler.nodes.ValueNode

org.graalvm.compiler.nodes.FixedNode

org.graalvm.compiler.nodes.FixedWithNextNode

org.graalvm.compiler.nodes.java.ReachabilityFenceNode

All Implemented Interfaces:

Cloneable, Formattable, CanonicalizableMarker, FixedNodeInterface, FixedWithNextNodeInterface, Canonicalizable, LIRLowerable, Virtualizable, ValueNodeInterface

public final class ReachabilityFenceNode
extends FixedWithNextNode
implements Virtualizable, Canonicalizable, LIRLowerable

Implements the semantics of Reference.reachabilityFence(java.lang.Object) without relying on a FrameState to keep values alive. This node does not prevent any escape analysis. When an object is virtualized, then this node keeps all non-primitive elements of the virtual object alive too, i.e., it ensures that there is no observable difference even for objects that are transitively reachable. This is an important part of the semantics of Reference.reachabilityFence(java.lang.Object). When an object is virtualized, also the virtualized object itself remains alive (i.e., it remains part of the ReachabilityFenceNode.values list. While this is not required for the semantics of Reference.reachabilityFence(java.lang.Object) from a GC point of view, it is useful when Reference.reachabilityFence(java.lang.Object) is used (or actually mis-used) to keep a value alive for the purpose of stack frame inspection.

Nested Class Summary

Nested classes/interfaces inherited from class org.graalvm.compiler.graph.Node

Node.ConstantNodeParameter, Node.EdgeVisitor, Node.IndirectCanonicalization, Node.InjectedNodeParameter, Node.Input, Node.NodeInsertionStackTrace, Node.NodeIntrinsic, Node.NodeIntrinsicFactory, Node.OptionalInput, Node.Successor, Node.ValueNumberable

Nested classes/interfaces inherited from interface org.graalvm.compiler.nodes.spi.Canonicalizable

Canonicalizable.Binary<T extends Node>, Canonicalizable.BinaryCommutative<T extends Node>, Canonicalizable.Ternary<T extends Node>, Canonicalizable.Unary<T extends Node>

Field Summary

Fields

Modifier and Type	Field and Description
static NodeClass<ReachabilityFenceNode>	TYPE

Fields inherited from class org.graalvm.compiler.nodes.FixedWithNextNode

next

Fields inherited from class org.graalvm.compiler.nodes.ValueNode

EMPTY_ARRAY, stamp

Fields inherited from class org.graalvm.compiler.graph.Node

NODE_LIST, NOT_ITERABLE, TRACK_CREATION_POSITION, WithAllEdges, WithNoEdges, WithOnlyInputEdges, WithOnlySucessorEdges

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ReachabilityFenceNode(ValueNode[] values)

Method Summary

Modifier and Type	Method and Description
Node	canonical(CanonicalizerTool tool) Implementations of this method can provide local optimizations like constant folding and strength reduction.
static ValueNode	create(ValueNode value)
static ReachabilityFenceNode	create(ValueNode[] values)
void	generate(NodeLIRBuilderTool gen)
NodeInputList<ValueNode>	getValues()
void	virtualize(VirtualizerTool tool) A node class can implement this method to convey information about what its effect would be if some of its inputs were virtualized.

Methods inherited from class org.graalvm.compiler.nodes.FixedWithNextNode

asFixedWithNextNode, next, setNext

Methods inherited from class org.graalvm.compiler.nodes.FixedNode

asFixedNode, verify

Methods inherited from class org.graalvm.compiler.nodes.ValueNode

asConstant, asJavaConstant, asNode, asSerializableConstant, checkReplaceAtUsagesInvariants, getStackKind, graph, hasUsagesOtherThan, inferStamp, isAllowedUsageType, isConstant, isConstantPredicate, isDefaultConstant, isIllegalConstant, isJavaConstant, isNullConstant, isSerializableConstant, recursivelyDataFlowEqualsUpTo, setStamp, stamp, updateStamp, updateUsagesInterface

Methods inherited from class org.graalvm.compiler.graph.Node

afterClone, applyInputs, applySuccessors, assertFalse, assertTrue, cfgPredecessors, cfgSuccessors, clearInputs, clearNodeSourcePosition, clearSuccessors, copyWithInputs, copyWithInputs, dataFlowEquals, dynamicNodeSizeEstimate, estimatedNodeCycles, estimatedNodeSize, fail, formatTo, getCreationPosition, getDebug, getDebugProperties, getDebugProperties, getInsertionPosition, getNodeClass, getNodeSourcePosition, getOptions, getUsageCount, hasExactlyOneUsage, hashCode, hasMoreThanOneUsage, hasNoUsages, hasOnlyUsagesOfType, hasUsages, hasUsagesOfType, inputPositions, inputs, isAlive, isDeleted, isUnregistered, markDeleted, maybeNotifyZeroUsages, modCount, predecessor, pushInputs, removeUsage, replaceAllInputs, replaceAndDelete, replaceAtAllUsages, replaceAtMatchingUsages, replaceAtPredecessor, replaceAtUsages, replaceAtUsages, replaceAtUsages, replaceAtUsages, replaceAtUsages, replaceAtUsagesAndDelete, replaceAtUsagesAndDelete, replaceFirstInput, replaceFirstSuccessor, safeDelete, setCreationPosition, setInsertionPosition, setNodeSourcePosition, singleUsage, successorPositions, successors, toString, toString, updateNodeSourcePosition, updatePredecessor, updateUsages, usages, valueEquals, verifyEdges, verifyInputs, verifySourcePosition, withNodeSourcePosition

Methods inherited from class java.lang.Object

clone, equals, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.graalvm.compiler.nodes.FixedNodeInterface

asFixedNode

Methods inherited from interface org.graalvm.compiler.nodes.ValueNodeInterface

asNode

Field Detail

TYPE

public static final NodeClass<ReachabilityFenceNode> TYPE

Constructor Detail

ReachabilityFenceNode

protected ReachabilityFenceNode(ValueNode[] values)

Method Detail

create

public static ValueNode create(ValueNode value)

create

public static ReachabilityFenceNode create(ValueNode[] values)

getValues

public NodeInputList<ValueNode> getValues()

virtualize

public void virtualize(VirtualizerTool tool)

Description copied from interface: Virtualizable

A node class can implement this method to convey information about what its effect would be if some of its inputs were virtualized. All modifications must be made through the supplied tool, and not directly on the node, because by the time this method is called the virtualized/non-virtualized state is still speculative and might not hold because of loops, etc.

Specified by:

virtualize in interface Virtualizable

Parameters:

tool - the tool used to describe the effects of this node

canonical

public Node canonical(CanonicalizerTool tool)

Description copied from interface: Canonicalizable

Implementations of this method can provide local optimizations like constant folding and strength reduction. Implementations should look at the properties and inputs of the current node and determine if there is a more optimal and always semantically correct replacement.
The return value determines the effect that the canonicalization will have:

• Returning an pre-existing node will replace the current node with the given one.
• Returning a newly created node (that was not yet added to the graph) will replace the current node with the given one, after adding it to the graph. If both the replacement and the replacee are anchored in control flow (fixed nodes), the replacement will be added to the control flow. It is invalid to replace a non-fixed node with a newly created fixed node (because its placement in the control flow cannot be determined without scheduling).
• Returning null will delete the current node and replace it with null at all usages. Note that it is not necessary to delete floating nodes that have no more usages this way - they will be deleted automatically.

Specified by:

canonical in interface Canonicalizable

Parameters:

tool - provides access to runtime interfaces like MetaAccessProvider

generate

public void generate(NodeLIRBuilderTool gen)

Specified by:

generate in interface LIRLowerable