Overview of passes that adjust packing of bridged headers. More...

Collaboration diagram for Packing of bridged and fixed-size headers:

Classes
class	BridgedPacking
	The pass analyzes the usage of bridged headers and adjusts their packing. More...

class	RenameArchParams
	Pass that governs replacement of the user-supplied parameter names with the corresponding parameter names defined in the architecture. More...

class	SubstitutePackedHeaders
	The pass substitutes bridged headers with adjusted ones and converts the IR into the backend form. More...

Typedefs
using	RepackedHeaderTypes = ordered_map<cstring, const IR::Type_StructLike *>
	Adjusted packing of bridged and fixed-size headers; output of BFN::BridgedPacking, input for BFN::SubstitutePackedHeaders.

Detailed Description

Overview of passes that adjust packing of bridged headers.

Packing of bridged headers is performed in order to satisfy constraints induced by the processing threads where the bridged headers are used. Bridging can be used from an ingress to an egress processing thread of a possibly different pipe, from an egress to an ingress processing thread of the same pipe in the case of a folded program, or the combination of both.

The egress to ingress bridging is available on Tofino 32Q with loopbacks present at pipes 1 and 3. It is not available on Tofino 64Q with no loopbacks.

The case of the combination of both bridging in a folded program is shown below:

Packets are processed in a "logical" pipe(line) that spans multiple "physical" pipe(line)s. Using the backend's terminology, the packet is processed by four threads of the IR::BFN::Pipe::thread_t type in a run-to-completion manner.

All bridged headers needs to be analyzed in all threads they are used in. They are emitted by the source thread and extracted by the destination thread. In the case above, if a bridged header is used in all threads, the analysis is performed on pairs (pipe0:ingress, pipe1:egress), (pipe1:egress, pipe1:ingress), and (pipe1:ingress, pipe0:egress) (following the arrows).

Packing of bridged headers is performed only for the headers/structs with the @flexible annotation and for resubmit headers, which are fixed-sized (transformed into the IR::BFN::Type_FixedSizeHeader type in midend).

The steps are as follows:

BFN::BridgedPacking: Perform some auxiliary passes and convert the midend IR towards the backend IR (BackendConverter).
BFN::BridgedPacking -> ExtractBridgeInfo::preorder(IR::P4Program): Find usages of bridged headers (CollectBridgedFieldsUse).
BFN::BridgedPacking -> ExtractBridgeInfo::end_apply(): For all pairs of gresses where the bridged headers are used, perform some auxiliary backend passes (under PackFlexibleHeaders) and collect the constraints of bridged headers (FlexiblePacking).
BFN::BridgedPacking -> ExtractBridgeInfo::end_apply() -> PackFlexibleHeaders::solve() -> FlexiblePacking::solve() -> PackWithConstraintSolver::solve() -> ConstraintSolver::solve(): Use Z3 solver to find a satisfying packing of the bridged headers, which is stored in the RepackedHeaderTypes map.
BFN::BridgedPacking -> PadFixedSizeHeaders: Look for fixed-size headers and add their adjusted packing to the RepackedHeaderTypes map.
The modifications of the auxiliary passes performed in 1., the converted backend IR, and the modifications of auxiliary backend passes performed in 3. are thrown away.
BFN::SubstitutePackedHeaders -> ReplaceFlexibleType::postorder: The solution found by the Z3 solver is used to substitute the original bridged headers with adjusted ones. Fixed-size headers are also substituted with adjusted ones.
BFN::SubstitutePackedHeaders: Perform the same auxiliary passes and convert the IR towards the backend IR as in 1. and perform the PostMidEndLast pass.

Class Documentation

◆ BridgedPacking

class BridgedPacking

The pass analyzes the usage of bridged headers and adjusts their packing.

Precondition: Apply this pass manager to IR::P4Program after midend processing.

Postcondition: The RepackedHeaderTypes map filled in with adjusted packing of bridged headers.

Inheritance diagram for BridgedPacking:

[legend]

Public Member Functions
	BridgedPacking (BFN_Options &options, RepackedHeaderTypes &repackMap, CollectSourceInfoLogging &sourceInfoLogging)

Public Member Functions inherited from P4::PassManager
	PassManager (const PassManager &)=default

	PassManager (const std::initializer_list< VisitorRef > &init)

	PassManager (PassManager &&)=default

void	addDebugHook (DebugHook h, bool recursive=false)

void	addDebugHooks (std::vector< DebugHook > hooks, bool recursive=false)

void	addPasses (const std::initializer_list< VisitorRef > &init)

const IR::Node *	apply_visitor (const IR::Node , const char =0) override

bool	backtrack (trigger &trig) override

PassManager *	clone () const override

void	early_exit ()

void	listPasses (std::ostream &, cstring sep) const

bool	never_backtracks () override

void	removePasses (const std::vector< cstring > &exclude)

void	setStopOnError (bool stop)

Public Member Functions inherited from P4::Visitor
virtual bool	check_clone (const Visitor *a)

virtual bool	check_global (cstring)

virtual void	clear_globals ()

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

Public Member Functions inherited from P4::Backtrack
Public Attributes
IR::Vector< IR::BFN::Pipe >	pipe

ordered_map< int, const IR::BFN::Pipe * >	pipes

P4::ReferenceMap	refMap

P4::TypeMap	typeMap

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

cstring	internalName

SplitFlowVisit_base *&	split_link

SplitFlowVisit_base *	split_link_mem = nullptr

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)

Protected Member Functions inherited from P4::PassManager
profile_t	init_apply (const IR::Node *root) override

void	runDebugHooks (const char visitorName, const IR::Node node)

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)

virtual void	visitAgain () const

virtual void	visitOnce () const

Protected Attributes inherited from P4::PassManager
safe_vector< DebugHook >	debugHooks

safe_vector< Visitor * >	passes

bool	running = false

unsigned	seqNo = 0

bool	stop_on_error = true

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

bool	joinFlows = false

bool	visitDagOnce = true

◆ RenameArchParams

class RenameArchParams

Pass that governs replacement of the user-supplied parameter names with the corresponding parameter names defined in the architecture.

Inheritance diagram for RenameArchParams:

[legend]

Public Member Functions
	RenameArchParams (P4::ReferenceMap refMap, P4::TypeMap typeMap)

◆ SubstitutePackedHeaders

class SubstitutePackedHeaders

The pass substitutes bridged headers with adjusted ones and converts the IR into the backend form.

Inheritance diagram for SubstitutePackedHeaders:

[legend]

Public Member Functions
	SubstitutePackedHeaders (BFN_Options &options, const RepackedHeaderTypes &repackedMap, CollectSourceInfoLogging &sourceInfoLogging)

const BFN::ProgramPipelines &	getPipelines () const

const IR::ToplevelBlock *	getToplevelBlock () const

Public Member Functions inherited from P4::PassManager
	PassManager (const PassManager &)=default

	PassManager (const std::initializer_list< VisitorRef > &init)

	PassManager (PassManager &&)=default

void	addDebugHook (DebugHook h, bool recursive=false)

void	addDebugHooks (std::vector< DebugHook > hooks, bool recursive=false)

void	addPasses (const std::initializer_list< VisitorRef > &init)

const IR::Node *	apply_visitor (const IR::Node , const char =0) override

bool	backtrack (trigger &trig) override

PassManager *	clone () const override

void	early_exit ()

void	listPasses (std::ostream &, cstring sep) const

bool	never_backtracks () override

void	removePasses (const std::vector< cstring > &exclude)

void	setStopOnError (bool stop)

Public Member Functions inherited from P4::Visitor
virtual bool	check_clone (const Visitor *a)

virtual bool	check_global (cstring)

virtual void	clear_globals ()

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

Public Member Functions inherited from P4::Backtrack
Public Attributes
IR::Vector< IR::BFN::Pipe >	pipe

ordered_map< int, const IR::BFN::Pipe * >	pipes

P4::ReferenceMap	refMap

P4::TypeMap	typeMap

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

cstring	internalName

SplitFlowVisit_base *&	split_link

SplitFlowVisit_base *	split_link_mem = nullptr

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)

Protected Member Functions inherited from P4::PassManager
profile_t	init_apply (const IR::Node *root) override

void	runDebugHooks (const char visitorName, const IR::Node node)

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)

virtual void	visitAgain () const

virtual void	visitOnce () const

Protected Attributes inherited from P4::PassManager
safe_vector< DebugHook >	debugHooks

safe_vector< Visitor * >	passes

bool	running = false

unsigned	seqNo = 0

bool	stop_on_error = true

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

bool	joinFlows = false

bool	visitDagOnce = true

Typedef Documentation

◆ RepackedHeaderTypes

using RepackedHeaderTypes = ordered_map<cstring, const IR::Type_StructLike *>

Adjusted packing of bridged and fixed-size headers; output of BFN::BridgedPacking, input for BFN::SubstitutePackedHeaders.

There are two sources of adjusted packing:

PackWithConstraintSolver::solve
PadFixedSizeHeaders::preorder

Adjusted packing is then used in the ReplaceFlexibleType pass.

Classes

Typedefs

Detailed Description

Class Documentation

◆ BridgedPacking

Public Member Functions

Public Attributes

Additional Inherited Members

◆ RenameArchParams

Public Member Functions

◆ SubstitutePackedHeaders

Public Member Functions

Public Attributes

Additional Inherited Members

Typedef Documentation

◆ RepackedHeaderTypes