tvm::relax::NestedMsg< T > Class Template Reference

Container that stores possibly nested message with leaf message type T. More...

#include <nested_msg.h>

Inheritance diagram for tvm::relax::NestedMsg< T >:

Collaboration diagram for tvm::relax::NestedMsg< T >:

Public Types
using	ContainerType = Object
using	LeafContainerType = typename T::ContainerType
Public Types inherited from tvm::runtime::ObjectRef
using	ContainerType = Object
	type indicate the container type. More...

Public Member Functions
	NestedMsg ()=default
	NestedMsg (const NestedMsg< T > &)=default
	NestedMsg (NestedMsg< T > &&)=default
NestedMsg< T > &	operator= (const NestedMsg< T > &)=default
NestedMsg< T > &	operator= (NestedMsg< T > &&)=default
	NestedMsg (ObjectPtr< Object > ptr)
	Construct from an ObjectPtr whose type already satisfies the constraint. More...
	NestedMsg (runtime::NullOptType)
	Nullopt handling. More...
	NestedMsg (std::nullptr_t)
NestedMsg< T > &	operator= (std::nullptr_t)
	NestedMsg (T other)
NestedMsg< T > &	operator= (T other)
	NestedMsg (Array< NestedMsg< T >, void > other)
NestedMsg< T > &	operator= (Array< NestedMsg< T >, void > other)
	NestedMsg (std::initializer_list< NestedMsg< T >> other)
NestedMsg< T > &	operator= (std::initializer_list< NestedMsg< T >> other)
	NestedMsg (int val)=delete
NestedMsg< T > &	operator= (int val)=delete
bool	operator== (std::nullptr_t) const
bool	operator!= (std::nullptr_t) const
bool	IsLeaf () const
bool	IsNull () const
bool	IsNested () const
T	LeafValue () const
Array< NestedMsg< T >, void >	NestedArray () const
Public Member Functions inherited from tvm::runtime::ObjectRef
	ObjectRef ()=default
	default constructor More...
	ObjectRef (ObjectPtr< Object > data)
	Constructor from existing object ptr. More...
bool	same_as (const ObjectRef &other) const
	Comparator. More...
bool	operator== (const ObjectRef &other) const
	Comparator. More...
bool	operator!= (const ObjectRef &other) const
	Comparator. More...
bool	operator< (const ObjectRef &other) const
	Comparator. More...
bool	defined () const
const Object *	get () const
const Object *	operator-> () const
bool	unique () const
int	use_count () const
template<typename ObjectType , typename = std::enable_if_t<std::is_base_of_v<Object, ObjectType>>>
const ObjectType *	as () const
	Try to downcast the internal Object to a raw pointer of a corresponding type. More...
template<typename ObjectRefType , typename = std::enable_if_t<std::is_base_of_v<ObjectRef, ObjectRefType>>>
Optional< ObjectRefType >	as () const
	Try to downcast the ObjectRef to a Optional<T> of the requested type. More...

Static Public Attributes
static constexpr bool	_type_is_nullable = true
Static Public Attributes inherited from tvm::runtime::ObjectRef
static constexpr bool	_type_is_nullable = true

Additional Inherited Members
Protected Member Functions inherited from tvm::runtime::ObjectRef
Object *	get_mutable () const
Static Protected Member Functions inherited from tvm::runtime::ObjectRef
template<typename T >
static T	DowncastNoCheck (ObjectRef ref)
	Internal helper function downcast a ref without check. More...
static void	FFIClearAfterMove (ObjectRef *ref)
	Clear the object ref data field without DecRef after we successfully moved the field. More...
template<typename ObjectType >
static ObjectPtr< ObjectType >	GetDataPtr (const ObjectRef &ref)
	Internal helper function get data_ as ObjectPtr of ObjectType. More...
Protected Attributes inherited from tvm::runtime::ObjectRef
ObjectPtr< Object >	data_
	Internal pointer that backs the reference. More...

Detailed Description

template<typename T>
class tvm::relax::NestedMsg< T >

Container that stores possibly nested message with leaf message type T.

NestedMsg is a helper structure to store intermediate message state in pass analysis so we can robustly handle message passing with the presence of nested tuple types.

Under the hood, NestedMsg[T] = Union[T, NullOpt, Array[NestedMsg[T]]]. Each nested message corresponds to the same nesting structure as the nested tuple types when we encounter them in analysis.

Relax support nested tuple structures in the IR. Nested tuple structure is important to support advanced groupings in cases such as gradient calculation and other scenarios.

The possible presence of nested tuple does mean that we need to to robustly handle analysis that contains nested tuple structures in a dataflow graph.

v1 = relu(v0)
v2 = exp(v0)
t = ((v0, v1), (v2,), v0)
t1 = t[0]
v3 = concat(t1)
v4 = t[2]
v5 = add(v4, v3)

Consider the above code sequence that contains a mixture of tuple nesting and normal operations. A common message-passing-based analysis will track messages attached to each intermediate variable.

Because the intermediate value can contain nested-tuples, we need to have abilities to nest messages according to tuple structure and propagate them along the way. In python, this simply corresponds to using a tuple to hold nested messages. This class provides a helper wrapper in C++ to present such possibly nested message for a given leaf message.

This design pattern is necessary to handle tuple values regardless of the normal form design of the IR to enable different messages for each tuple component without enforcing all tuple elements to have the same message.

Please consider the following patterns in our pass:

On a forward propagation message passing analysis:

• Create map [leafnode=>NestedMsg<T>], scan forward
• input_msg = [MapToNestedMsg<T>(x, lookup_map) for x in call->args]
• output_msg = ForwardProp[call->op](input_msg, call)
• map[binding->var] = output_msg
• Use MapToNestedMsg to remap the remaining body.

On a backward propagation message passing analysis:

• Create map [leafnode=>NestedMsg<T>], scan backward
• output_msg = lookup map(binding->var)
• handle case when output_msg is null
• input_msg = BackProp[call->op](out_msg, call)
• for arg, msg in zip(call->args, input_msg), DecomposeNestedMessage(arg, msg, lambda node, m: update_map(node, m))
• update_map(node, m) => CombineNestedMessage(map[node], m)

Here leafnode is a node that you would like to propagate messages to such as constant, var and should not include tuple.

We also recommend writing unit-test cases that involve nested tuple composition and decomposition.

See also

MapToNestedMsg, DecomposeNestedMsg, CombineNestedMsg, ForEachLeaf, Equal

Note

If you want to write robust message passing-based analysis for programs that can contain nested tuples, you likely need to use this class or logic of a similar kind.

Member Typedef Documentation

ContainerType

template<typename T >

using tvm::relax::NestedMsg< T >::ContainerType = Object

LeafContainerType

template<typename T >

using tvm::relax::NestedMsg< T >::LeafContainerType = typename T::ContainerType

Constructor & Destructor Documentation

NestedMsg() [1/10]

template<typename T >

tvm::relax::NestedMsg< T >::NestedMsg ( )

default

NestedMsg() [2/10]

template<typename T >

tvm::relax::NestedMsg< T >::NestedMsg ( const NestedMsg< T > &  )

default

NestedMsg() [3/10]

template<typename T >

tvm::relax::NestedMsg< T >::NestedMsg ( NestedMsg< T > &&  )

default

NestedMsg() [4/10]

template<typename T >

tvm::relax::NestedMsg< T >::NestedMsg ( ObjectPtr< Object >  ptr )

inlineexplicit

Construct from an ObjectPtr whose type already satisfies the constraint.

Parameters

ptr

NestedMsg() [5/10]

template<typename T >

tvm::relax::NestedMsg< T >::NestedMsg ( runtime::NullOptType  )

inline

Nullopt handling.

NestedMsg() [6/10]

template<typename T >

tvm::relax::NestedMsg< T >::NestedMsg ( std::nullptr_t  )

inlineexplicit

NestedMsg() [7/10]

template<typename T >

tvm::relax::NestedMsg< T >::NestedMsg ( T  other )

inline

NestedMsg() [8/10]

template<typename T >

tvm::relax::NestedMsg< T >::NestedMsg ( Array< NestedMsg< T >, void >  other )

inline

NestedMsg() [9/10]

template<typename T >

tvm::relax::NestedMsg< T >::NestedMsg ( std::initializer_list< NestedMsg< T >>  other )

inline

NestedMsg() [10/10]

template<typename T >

tvm::relax::NestedMsg< T >::NestedMsg ( int  val )

explicitdelete

Member Function Documentation

IsLeaf()

template<typename T >

bool tvm::relax::NestedMsg< T >::IsLeaf ( ) const

inline

Returns

Whether the nested message is not-null leaf value

IsNested()

template<typename T >

bool tvm::relax::NestedMsg< T >::IsNested ( ) const

inline

Returns

Whether the nested message is nested

IsNull()

template<typename T >

bool tvm::relax::NestedMsg< T >::IsNull ( ) const

inline

Returns

Whether the nested message is null

LeafValue()

template<typename T >

T tvm::relax::NestedMsg< T >::LeafValue ( ) const

inline

Returns

The underlying leaf value.

Note

This function checks if the msg is leaf.

NestedArray()

template<typename T >

Array<NestedMsg<T>, void> tvm::relax::NestedMsg< T >::NestedArray ( ) const

inline

Returns

a corresponding nested array.

Note

This checks if the underlying data type is array.

operator!=()

template<typename T >

bool tvm::relax::NestedMsg< T >::operator!= ( std::nullptr_t  ) const

inline

operator=() [1/7]

template<typename T >

NestedMsg<T>& tvm::relax::NestedMsg< T >::operator= ( Array< NestedMsg< T >, void >  other )

inline

operator=() [2/7]

template<typename T >

NestedMsg<T>& tvm::relax::NestedMsg< T >::operator= ( const NestedMsg< T > &  )

default

operator=() [3/7]

template<typename T >

NestedMsg<T>& tvm::relax::NestedMsg< T >::operator= ( int  val )

delete

operator=() [4/7]

template<typename T >

NestedMsg<T>& tvm::relax::NestedMsg< T >::operator= ( NestedMsg< T > &&  )

default

operator=() [5/7]

template<typename T >

NestedMsg<T>& tvm::relax::NestedMsg< T >::operator= ( std::initializer_list< NestedMsg< T >>  other )

inline

operator=() [6/7]

template<typename T >

NestedMsg<T>& tvm::relax::NestedMsg< T >::operator= ( std::nullptr_t  )

inline

operator=() [7/7]

template<typename T >

NestedMsg<T>& tvm::relax::NestedMsg< T >::operator= ( T  other )

inline

operator==()

template<typename T >

bool tvm::relax::NestedMsg< T >::operator== ( std::nullptr_t  ) const

inline

Member Data Documentation

_type_is_nullable

template<typename T >

constexpr bool tvm::relax::NestedMsg< T >::_type_is_nullable = true

staticconstexpr

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

• include/tvm/relax/nested_msg.h