codi::EnzymeExternalFunctionHelper< T_Type > Struct Template Reference

Helper class for the implementation of an external function with Enzyme in CoDiPack. More...

#include <enzymeExternalFunctionHelper.hpp>

Inheritance diagram for codi::EnzymeExternalFunctionHelper< T_Type >:

Public Types
using	Base = ExternalFunctionHelper< Type >
	Base class abbreviation.
using	Identifier = typename Type::Identifier
	See LhsExpressionInterface.
using	PrimalFunc = typename Base::PrimalFunc
	See ExternalFunctionHelper.
using	Real = typename Type::Real
	See LhsExpressionInterface.
using	Tape = typename Type::Tape
	See LhsExpressionInterface.
using	Type = T_Type
	See ExternalFunctionHelper.
Public Types inherited from codi::ExternalFunctionHelper< T_Type, T_Synchronization, T_ThreadInformation >
using	ForwardFunc = void(*)(Real const *x, Real const *x_d, size_t m, Real *y, Real *y_d, size_t n, ExternalFunctionUserData *d)
	Function interface for the forward AD call of an external function.
using	Identifier = typename Type::Identifier
	See LhsExpressionInterface.
using	PrimalFunc = void(*)(Real const *x, size_t m, Real *y, size_t n, ExternalFunctionUserData *d)
	Function interface for the primal call of an external function.
using	Real = typename Type::Real
	See LhsExpressionInterface.
using	ReverseFunc = void(*)(Real const *x, Real *x_b, size_t m, Real const *y, Real const *y_b, size_t n, ExternalFunctionUserData *d)
	Function interface for the reverse AD call of an external function.
using	Synchronization = T_Synchronization
	See ExternalFunctionHelper.
using	Tape = typename Type::Tape
	See LhsExpressionInterface.
using	ThreadInformation = T_ThreadInformation
	See ExternalFunctionHelper.
using	Type = T_Type
	See ExternalFunctionHelper.

Public Member Functions
template<PrimalFunc func>
void	callAndAddToTape ()
template<PrimalFunc func>
void	callAndAddToTape (Type const *x, size_t m, Type *y, size_t n)
	Adds all inputs in x and outputs in y to the external function and then calls callAndAddToTape().
	EnzymeExternalFunctionHelper ()
	Constructor.
Public Member Functions inherited from codi::ExternalFunctionHelper< T_Type, T_Synchronization, T_ThreadInformation >
void	addInput (Type const &input)
	Add an input value.
void	addOutput (Type &output)
	Add an output value.
void	addToTape (ReverseFunc reverseFunc, ForwardFunc forwardFunc=nullptr, PrimalFunc primalFunc=nullptr)
	Add the external function to the tape.
template<typename Data >
void	addUserData (Data const &data)
	Add user data. See ExternalFunctionUserData for details.
void	callPrimalFunc (PrimalFunc func)
template<typename FuncObj , typename... Args>
void	callPrimalFuncWithADType (FuncObj &func, Args &&... args)
void	disableInputPrimalStore ()
	Do not store primal input values. In function calls, pointers to primal inputs will be null.
void	disableOutputPrimalStore ()
	Do not store primal output values. In function calls, pointers to primal outputs will be null.
void	disableRenewOfPrimalValues ()
	Do not update the inputs and outputs from the primal values of the tape. Has no effect on Jacobian tapes.
void	enableReallocationOfPrimalValueVectors ()
	ExternalFunctionHelper (bool primalFuncUsesADType=false)
	Constructor.
ExternalFunctionUserData &	getExternalFunctionUserData ()
	~ExternalFunctionHelper ()
	Destructor.

Additional Inherited Members
Protected Attributes inherited from codi::ExternalFunctionHelper< T_Type, T_Synchronization, T_ThreadInformation >
EvalData *	data
	External function data.
bool	getPrimalValuesFromPrimalValueVector
std::vector< Type * >	outputValues
	References to output values.
bool	reallocatePrimalVectors
bool	storeInputOutputForPrimalEval
	If a primal call with a self-implemented function will be done.
bool	storeInputPrimals
	If input primals are stored. Can be disabled by the user.
bool	storeOutputPrimals
	If output primals are stored. Can be disabled by the user.
std::vector< Real >	y
	Shared vector of output variables.

Detailed Description

template<typename T_Type>
struct codi::EnzymeExternalFunctionHelper< T_Type >

Helper class for the implementation of an external function with Enzyme in CoDiPack.

The class helps the user to create derivative functions with Enzyme and add them to the tape. See ExternalFunctionHelper for the general configuration options and procedures. This class only supports the operation mode 1 "Implemented primal function". In this implementation, this mode requires just one call to callAndAddToTape() which calls the primal function and adds it to the tape.

The procedure of pushing a differentiated function with Enzyme is as follows.

1. All function inputs and outputs are specified.
2. Call callAndAddToTape method with the primal function.

An example is:

  codi::EnzymeExternalFunctionHelper<Real> eh;
 
  eh.addInput(x);
  eh.addOutput(y[1]);
 
  eh.template callAndAddToTape<func_prim>();

This helper provides an additional overload where the inputs and outputs can be directly added:

  codi::ExternalFunctionHelper<Real> ehS;
 
  eh.template callAndAddToTape<func_prim>(&x, 1, &y[2], 1);

The full example can be found at Example 24 - Enzyme external function helper.

Template Parameters

T_Type

The CoDiPack type that is used outside of the external function.

Member Function Documentation

callAndAddToTape()

template<typename T_Type >

template<PrimalFunc func>

void codi::EnzymeExternalFunctionHelper< T_Type >::callAndAddToTape ( )

inline

Calls the primal function and adds the Enzyme generated functions to the tape.

Is a combination of ExternalFunctionHelper::callPrimalFunc and ExternalFunctionHelper::addToTape.

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

• include/codi/tools/helpers/enzymeExternalFunctionHelper.hpp