loki.transformations.split_read_write

Classes

SplitReadWriteTransformation(dimensions)	When accumulating values to multiple components of an array, a compiler cannot rule out the possibility that the indices alias the same address.
SplitReadWriteWalk(dimensions, variable_map)	A Transformer class to traverse the IR, in-place replace read-write assignments with reads, and build a transformer map for the corresponding writes.

class SplitReadWriteTransformation(dimensions)

Bases: Transformation

When accumulating values to multiple components of an array, a compiler cannot rule out the possibility that the indices alias the same address. Consider for example the following code:

!$loki split-read-write
do jlon=1,nproma
   var(jlon, n1) = var(jlon, n1) + 1.
   var(jlon, n2) = var(jlon, n2) + 1.
enddo
!$loki end split-read-write

In the above example, there is no guarantee that n1 and n2 do not in fact point to the same location. Therefore the load and store instructions for var have to be executed in order.

For cases where the user knows n1 and n2 indeed represent distinct locations, this transformation provides a pragma assisted mechanism to split the reads and writes, and therefore make the loads independent from the stores. The above code would therefore be transformed to:

!$loki split-read-write
do jlon=1,nproma
   loki_temp_0(jlon) = var(jlon, n1) + 1.
   loki_temp_1(jlon) = var(jlon, n2) + 1.
enddo

do jlon=1,nproma
   var(jlon, n1) = loki_temp_0(jlon)
   var(jlon, n2) = loki_temp_1(jlon)
enddo
!$loki end split-read-write

Parameters:

dimensions (list) – A list of Dimension objects corresponding to all Loop`s in the `!$loki split-read-write`` region.

item_filter = (<class 'loki.batch.item.ProcedureItem'>,)

transform_subroutine(routine, **kwargs)

Defines the transformation to apply to Subroutine items.

For transformations that modify Subroutine objects, this method should be implemented. It gets called via the dispatch method apply().

Parameters:

• routine (Subroutine) – The subroutine to be transformed.

• **kwargs (optional) – Keyword arguments for the transformation.