codi::IndexManagerInterface< T_Index > Struct Template Reference

Indices enable the mapping of primal values to their adjoint counterparts. More...

#include <indexManagerInterface.hpp>

Inheritance diagram for codi::IndexManagerInterface< T_Index >:

Public Types
using	Index = T_Index
	See IndexManagerInterface.

Public Member Functions
Misc functions
void	addToTapeValues (TapeValues &values) const
	Add storage and other information to the tape values.
Index	getLargestCreatedIndex () const
	Returns the largest created index.

Static Public Attributes
Global constants
static Index constexpr	InactiveIndex = Index(0)
	Default inactive index for all index managers.
static Index constexpr	InvalidIndex
	Default invalid index for all index mangers (max value for unsigned types).

Identifier handling
static bool constexpr	CopyNeedsStatement
	True if no copy optimization is implemented. See IndexManagerInterface.
static bool constexpr	IsLinear
	True if identifiers are coupled to the statements. See IndexManagerInterface.
static bool constexpr	NeedsStaticStorage = false
	True if the index manager is specific to a tape type (and not a tape instance). See IndexManagerInterface.
template<typename Tape >
bool	assignIndex (Index &index)
	Call on assignment of a primal value, e.g. on w for w = a + b.
template<typename Tape >
bool	assignUnusedIndex (Index &index)
	Call on registering input values.
template<typename Tape >
void	copyIndex (Index &lhs, Index const &rhs)
	Call on copy of a primal value, e.g. w = a.
template<typename Tape >
void	freeIndex (Index &index)
	Call on destruction of a primal value. Usually called from the destructor.
void	reset ()
	Reset for a new recording.

Detailed Description

template<typename T_Index>
struct codi::IndexManagerInterface< T_Index >

Indices enable the mapping of primal values to their adjoint counterparts.

In operator overloading AD, each primal variable (e.g. ) needs to be mapped to the adjoint counterpart (e.g. . Since the adjoint cannot be stored in the primal, an identifier (usually an index) is associated with each primal. This identifier is then used to access the adjoint variable.

The interface defines the three basic operations which can be applied to a variable: assign, copy and free. For each of these operations on the primal variable, the corresponding function on the identifier needs to be called.

freeIndex() only needs to be called in destructors. If a variable is overwritten, only assign needs to be called on the left hand side identifier. The index manager has to decide how the old identifier is handled.

assignUnusedIndex() provides identifiers that have not been used after the last reset. These identifiers can be used for input values of the program because the adjoint will not be overwritten by intermediate variables.

CopyNeedsStatement is a static check if the index manager implements a copy optimization, that is, if it creates a new identifier for the left hand side or copies the right hand side identifier instead. Not all index management approaches admit a copy optimization.

IsLinear indicates whether the indices are coupled to the statements of a program. The tape needs to be managed accordingly.

NeedsStaticStorage indicates whether the index manager is specific to a tape type (as opposed to a specific tape instance). Depending on this setting, it is stored statically or non-statically in the tape.

Mathematical and implementational details are explained in SBG2021Index.

Template Parameters

T_Index

Type for the identifier, usually an integer type.

Member Function Documentation

addToTapeValues()

template<typename T_Index >

void codi::IndexManagerInterface< T_Index >::addToTapeValues

(

TapeValues &

values

)

const

Add storage and other information to the tape values.

Parameters

[in,out]

values

Will only create new data entries and no new section.

assignIndex()

template<typename T_Index >

template<typename Tape >

bool codi::IndexManagerInterface< T_Index >::assignIndex

(

Index &

index

)

Call on assignment of a primal value, e.g. on w for w = a + b.

Returns

true if new indices have been generated internally.

assignUnusedIndex()

template<typename T_Index >

template<typename Tape >

bool codi::IndexManagerInterface< T_Index >::assignUnusedIndex

(

Index &

index

)

Call on registering input values.

Returns

true if new indices have been generated internally.

getLargestCreatedIndex()

template<typename T_Index >

Index codi::IndexManagerInterface< T_Index >::getLargestCreatedIndex

(

)

const

Returns the largest created index.

This is the largest entry in the adjoint vectors created by the tapes.

Member Data Documentation

CopyNeedsStatement

template<typename T_Index >

bool constexpr codi::IndexManagerInterface< T_Index >::CopyNeedsStatement

staticconstexpr

Initial value:

=
           false

True if no copy optimization is implemented. See IndexManagerInterface.

InvalidIndex

template<typename Index >

Index constexpr codi::IndexManagerInterface< Index >::InvalidIndex

staticconstexpr

Initial value:

=
          Index(-1)

Default invalid index for all index mangers (max value for unsigned types).

IsLinear

template<typename T_Index >

bool constexpr codi::IndexManagerInterface< T_Index >::IsLinear

staticconstexpr

Initial value:

=
           false

True if identifiers are coupled to the statements. See IndexManagerInterface.

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The documentation for this struct was generated from the following file:

• include/codi/tapes/indices/indexManagerInterface.hpp