Package org.apache.sysds.hops.rewrite

Class RewriteRemoveUnnecessaryCasts

java.lang.Object

org.apache.sysds.hops.rewrite.HopRewriteRule

org.apache.sysds.hops.rewrite.RewriteRemoveUnnecessaryCasts

public class RewriteRemoveUnnecessaryCasts
extends HopRewriteRule

Rule: RemoveUnnecessaryCasts. For all value type casts check if they are really necessary. If both cast input and output type are the same, the cast itself is redundant. There are two use case where this can arise: (1) automatically inserted casts on function inlining (in case of unknown value types), and (2) explicit script-level value type casts, that might be redundant according to the read input data. The benefit of this rewrite is negligible for scalars. However, when we support matrices with different value types, those casts might refer to matrices and with that incur large costs.

Constructor Summary

Constructors

Constructor	Description
RewriteRemoveUnnecessaryCasts()

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 Details

RewriteRemoveUnnecessaryCasts

public RewriteRemoveUnnecessaryCasts()

Method Details

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