VariableMappingMethod

#include <poplar/VariableMappingMethod.hpp>
namespace poplar

Poplar classes and functions.

A VectorList is a list of vectors with a specific layout and with the usage semantics of a 2D vector.

A 1D vector must be laid out in a contiguous memory region. A 2D vector is a vector of 1D vectors. Each of these 1D vectors that make up a 2D vector is called a “sub-vector” for the remainder of this document. The elements of a 2D vector can be accessed by indexing the 2D vector along the outer and inner dimensions as A[outer][inner].

The following two categories of layouts are supported:

  1. VectorListLayout::DELTANELEMENTS is a memory efficient 2D vector layout. For legacy systems VectorListLayout::DELTAN served a similar purpose. Each sub-vector must be laid out as a contiguous memory region but the sub-vectors may may not be laid out contiguous with respect to each other in memory. Each sub-vector may have a different length.

  2. VectorListLayout::ONE_PTR and other VectorListLayout layouts that are prefixed by SCALED_PTR are for Poplar runtime use only.

Enums

enum class VariableMappingMethod

When variables are added to the graph, a tile mapping can be created.

This class enumerates the method for creating that mapping.

Values:

enumerator NONE

No mapping is created.

The tile mapping will be set later via Graph::setTileMapping.

enumerator LINEAR

The variable will be spread evenly across the tiles with the element ordering matching the tile number ordering.

The tile mapping can also be overridden later via Graph::setTileMapping.

Functions

std::string toString(const VariableMappingMethod &method)