Package org.apache.sysds.hops.rewrite

Class RewriteElementwiseMultChainOptimization

java.lang.Object

org.apache.sysds.hops.rewrite.HopRewriteRule

org.apache.sysds.hops.rewrite.RewriteElementwiseMultChainOptimization

public class RewriteElementwiseMultChainOptimization
extends HopRewriteRule

Prerequisite: RewriteCommonSubexpressionElimination must run before this rule. Rewrite a chain of element-wise multiply hops that contain identical elements. For example `(B * A) * B` is rewritten to `A * (B^2)` (or `(B^2) * A`), where `^` is element-wise power. The order of the multiplicands depends on their data types, dimensions (matrix or vector), and sparsity. Does not rewrite in the presence of foreign parents in the middle of the e-wise multiply chain, since foreign parents may rely on the individual results. Does not perform rewrites on an element-wise multiply if its dimensions are unknown. The new order of element-wise multiply chains is as follows:

     (((unknown * object * frame) * ([least-nnz-matrix * matrix] * most-nnz-matrix))
      * ([least-nnz-row-vector * row-vector] * most-nnz-row-vector))
     * ([[scalars * least-nnz-col-vector] * col-vector] * most-nnz-col-vector)
 

Identical elements are replaced with powers.

Constructor Summary

Constructors

Constructor	Description
RewriteElementwiseMultChainOptimization()

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

RewriteElementwiseMultChainOptimization

public RewriteElementwiseMultChainOptimization()

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