org.graalvm.compiler.phases.graph

Class FixedNodeRelativeFrequencyCache

java.lang.Object

org.graalvm.compiler.phases.graph.FixedNodeRelativeFrequencyCache

All Implemented Interfaces:

ToDoubleFunction<FixedNode>

public class FixedNodeRelativeFrequencyCache
extends Object
implements ToDoubleFunction<FixedNode>

Compute relative frequencies for fixed nodes on the fly and cache them at AbstractBeginNodes.

Constructor Summary

Constructors

Constructor and Description
FixedNodeRelativeFrequencyCache()

Method Summary

Modifier and Type	Method and Description
double	applyAsDouble(FixedNode node) Given a FixedNode this method finds the most immediate AbstractBeginNode preceding it that either: has no predecessor (ie, the begin-node is a merge, in particular a loop-begin, or the start-node) has a control-split predecessor

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FixedNodeRelativeFrequencyCache

public FixedNodeRelativeFrequencyCache()

Method Detail

applyAsDouble

public double applyAsDouble(FixedNode node)

Given a FixedNode this method finds the most immediate AbstractBeginNode preceding it that either:

• has no predecessor (ie, the begin-node is a merge, in particular a loop-begin, or the start-node)
• has a control-split predecessor

The thus found AbstractBeginNode is equi-probable with the FixedNode it was obtained from. When computed for the first time (afterwards a cache lookup returns it) that relative frequency is computed as follows, again depending on the begin-node's predecessor:

• No predecessor. In this case the begin-node is either:
• a merge-node, whose relative frequency adds up those of its forward-ends
• a loop-begin, with frequency as above multiplied by the loop-frequency
• Control-split predecessor: frequency of the branch times that of the control-split

As an exception to all the above, a frequency of 1 is assumed for a FixedNode that appears to be dead-code (ie, lacks a predecessor).

Specified by:

applyAsDouble in interface ToDoubleFunction<FixedNode>