Package org.apache.sysds.hops.rewrite

Class RewriteRemoveReadAfterWrite

java.lang.Object

org.apache.sysds.hops.rewrite.HopRewriteRule

org.apache.sysds.hops.rewrite.RewriteRemoveReadAfterWrite

public class RewriteRemoveReadAfterWrite
extends HopRewriteRule

Rule: RemoveReadAfterWrite. If there is a persistent read with the same filename as a persistent write, and read has a higher line number than the write, we remove the read and consume the write input directly. This is important for two reasons (1) correctness and (2) performance. Without this rewrite, we could not guarantee the order of read-after-write because there is not data dependency

Constructor Summary

Constructors

Constructor	Description
RewriteRemoveReadAfterWrite()

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

RewriteRemoveReadAfterWrite

public RewriteRemoveReadAfterWrite()

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