Merge POV bits. More...

Inheritance diagram for BFN::UpdatePovBits:

Public Member Functions
	UpdatePovBits (const PhvInfo &phv, const HeaderValidityAnalysis &hva, const ordered_map< const PHV::Field , const PHV::Field > &merge_pov)

Public Member Functions inherited from P4::Transform
const IR::Node *	apply_visitor (const IR::Node , const char name=0) override

profile_t	init_apply (const IR::Node *root) override

virtual void	loop_revisit (const IR::Node *)

virtual const IR::Node *	postorder (IR::Node *n)

virtual const IR::Node *	preorder (IR::Node *n)

void	prune ()

virtual void	revisit (const IR::Node , const IR::Node )

void	revisit_visited ()

bool	visit_in_progress (const IR::Node *) const

void	visitAgain () const override

void	visitOnce () const override

Public Member Functions inherited from P4::Visitor
virtual bool	check_global (cstring)

virtual void	clear_globals ()

virtual Visitor *	clone () const

virtual ControlFlowVisitor *	controlFlowVisitor ()

virtual void	end_apply ()

virtual void	end_apply (const IR::Node *root)

virtual void	erase_global (cstring)

template<class T >
const T *	findContext () const

template<class T >
const T *	findContext (const Context *&c) const

template<class T >
const T *	findOrigCtxt () const

template<class T >
const T *	findOrigCtxt (const Context *&c) const

virtual Visitor &	flow_clone ()

virtual void	flow_merge (Visitor &)

virtual bool	flow_merge_closure (Visitor &)

virtual void	flow_merge_global_from (cstring)

virtual void	flow_merge_global_to (cstring)

const Context *	getChildContext () const

int	getChildrenVisited () const

const Context *	getContext () const

int	getContextDepth () const

const IR::Node *	getCurrentNode () const

template<class T >
const T *	getCurrentNode () const

const IR::Node *	getOriginal () const

template<class T >
const T *	getOriginal () const

template<class T >
const T *	getParent () const

virtual bool	has_flow_joins () const

profile_t	init_apply (const IR::Node root, const Context parent_context)

bool	isInContext (const IR::Node *n) const

virtual const char *	name () const

template<class T >
void	parallel_visit (const IR::Vector< T > &v, const char *name, int cidx)

template<class T >
void	parallel_visit (const IR::Vector< T > &v, const char *name=0)

template<class T >
void	parallel_visit (IR::Vector< T > &v, const char *name, int cidx)

template<class T >
void	parallel_visit (IR::Vector< T > &v, const char *name=0)

void	print_context () const

const Visitor &	setCalledBy (const Visitor *visitor)

void	setName (const char *name)

void	visit (const IR::Node &n, const char *name, int cidx)

void	visit (const IR::Node &n, const char *name=0)

void	visit (const IR::Node &n, const char name, int cidx)

void	visit (const IR::Node &n, const char name=0)

void	visit (const IR::Node const &n, const char name, int cidx)

void	visit (const IR::Node const &n, const char name=0)

void	visit (IR::Node &n, const char *name, int cidx)

void	visit (IR::Node &n, const char *name=0)

void	visit (IR::Node &, const char =0, int=0)

template<class T , typename = std::enable_if_t<Util::has_SourceInfo_v<T> && !std::is_pointer_v<T>>, class... Args>
void	warn (const int kind, const char *format, const T &node, Args &&...args)
	The const ref variant of the above.

template<class T , typename = std::enable_if_t<Util::has_SourceInfo_v<T>>, class... Args>
void	warn (const int kind, const char format, const T node, Args &&...args)

bool	warning_enabled (int warning_kind) const

Protected Member Functions
Visitor::profile_t	init_apply (const IR::Node *root) override

const IR::Node *	preorder (IR::BFN::ChecksumEntry *csum) override

const IR::Node *	preorder (IR::BFN::Emit *emit) override

const IR::Node *	preorder (IR::HeaderOrMetadata *h) override

Protected Member Functions inherited from P4::Transform
const IR::Node *	transform_child (const IR::Node *child)

Protected Member Functions inherited from P4::Visitor
virtual void	init_join_flows (const IR::Node *)

virtual bool	join_flows (const IR::Node *)

virtual void	post_join_flows (const IR::Node , const IR::Node )

void	visit_children (const IR::Node *, std::function< void()> fn)

Protected Attributes
ordered_map< cstring, const IR::Member * >	fieldNameToExpressionsMap
	Map of IR::Expression objects corresponding to the field names.

const HeaderValidityAnalysis &	hva

const ordered_map< const PHV::Field , const PHV::Field > &	merge_pov

const PhvInfo &	phv

std::set< cstring >	skip_stack_pov_bits

std::set< cstring >	stack_pov_bits
	Names of stack POV bits.

Protected Attributes inherited from P4::Transform
bool	forceClone = false

Protected Attributes inherited from P4::Visitor
bool	dontForwardChildrenBeforePreorder = false

bool	joinFlows = false

bool	visitDagOnce = true

Additional Inherited Members
Public Types inherited from P4::Visitor
typedef Visitor_Context	Context

Static Public Member Functions inherited from P4::Visitor
static cstring	demangle (const char *)

static bool	warning_enabled (const Visitor *visitor, int warning_kind)

Public Attributes inherited from P4::Visitor
const Visitor *	called_by = nullptr

cstring	internalName

SplitFlowVisit_base *&	split_link

SplitFlowVisit_base *	split_link_mem = nullptr

Detailed Description

Merge POV bits.

Merge POV bits to allow FDE entries to be combined. Useful to increase deparser FDE packing density when there are many small headers.

An earlier pass identifies the sources and targets for POV merges.

The merging performs these operations:

Parser: eliminates constant-one extracts of the POV sources (only the extract to the target needs to be executed).
MAU: set valid/invalid of the sources are eliminated (only set valid/invalid on the destinations needs to be kept.
Deparser: source pov bits in emit statements are replaced by aliases to the target pov bits.
General: member references to source pov bits statements are replaced by aliases to the target pov bits.

Header stacks are handled differently because valid bits are already aliases to stkvalid slices. In this case:

Push/pop operations (recorded as $stkvalid manipulations in HeaderValidityAnalysis) override merging any POV bits in the stack.
Parser extracts and MAU operations are kept in order to maintain the correctness of all bits in the stkvalid vector. (Pushing/popping requires that all bits be updated.)
Deparser source pov bit references are replaced with target pov bit references (cannot replace with an alias because the $valid bits are already aliased to $stkvalid slices and this would cause conflicting aliasing).

Member Function Documentation

◆ init_apply()

Visitor::profile_t BFN::UpdatePovBits::init_apply ( const IR::Node * root )

inlineoverrideprotectedvirtual

Reimplemented from P4::Visitor.

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ init_apply()