Package org.apache.sysds.hops.rewrite

Class RewriteCommonSubexpressionElimination

java.lang.Object

org.apache.sysds.hops.rewrite.HopRewriteRule

org.apache.sysds.hops.rewrite.RewriteCommonSubexpressionElimination

public class RewriteCommonSubexpressionElimination
extends HopRewriteRule

Rule: CommonSubexpressionElimination. For all statement blocks, eliminate common subexpressions within dags by merging equivalent operators (same input, equal parameters) bottom-up. For the moment, this only applies within a dag, later this should be extended across statements block (global, inter-procedure).

Constructor Summary

Constructors

Constructor	Description
RewriteCommonSubexpressionElimination()
RewriteCommonSubexpressionElimination(boolean mergeLeafs)

Method Summary

Modifier and Type	Method	Description
Hop	rewriteHopDAG(Hop root, ProgramRewriteStatus state)	Handle a predicate hop DAG with exactly one root.
ArrayList<Hop>	rewriteHopDAGs(ArrayList<Hop> roots, ProgramRewriteStatus state)	Handle a generic (last-level) hop DAG with multiple roots.

Methods inherited from class java.lang.Object

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

Constructor Detail

RewriteCommonSubexpressionElimination

public RewriteCommonSubexpressionElimination()

RewriteCommonSubexpressionElimination

public RewriteCommonSubexpressionElimination(boolean mergeLeafs)

Method Detail

rewriteHopDAGs

public ArrayList<Hop> rewriteHopDAGs(ArrayList<Hop> roots,
                                     ProgramRewriteStatus state)

Description copied from class: HopRewriteRule

Handle a generic (last-level) hop DAG with multiple roots.

Specified by:

rewriteHopDAGs in class HopRewriteRule

Parameters:

roots - high-level operator roots

state - program rewrite status

Returns:

list of high-level operators

rewriteHopDAG

public Hop rewriteHopDAG(Hop root,
                         ProgramRewriteStatus state)

Description copied from class: HopRewriteRule

Handle a predicate hop DAG with exactly one root.

Specified by:

rewriteHopDAG in class HopRewriteRule

Parameters:

root - high-level operator root

state - program rewrite status

Returns:

high-level operator