sdfg::transformations::SoftwarePipelining Class Reference

Software-pipeline a sequential panel loop that cooperatively stages a shared-memory tile each iteration (the structure LocalStorage emits). More...

#include <sdfg/tiles/transformations/software_pipelining.h>

Inheritance diagram for sdfg::transformations::SoftwarePipelining:

Public Member Functions
	SoftwarePipelining (structured_control_flow::StructuredLoop &loop, size_t stages=2, bool single_operand=false, bool register_staged=false)
virtual std::string	name () const override
	Get the name of this transformation.
virtual bool	can_be_applied (builder::StructuredSDFGBuilder &builder, analysis::AnalysisManager &analysis_manager) override
	Check if this transformation can be safely applied.
virtual void	apply (builder::StructuredSDFGBuilder &builder, analysis::AnalysisManager &analysis_manager) override
	Apply this transformation to the SDFG.
virtual void	to_json (nlohmann::json &j) const override
	Serialize this transformation to JSON.
Public Member Functions inherited from sdfg::transformations::Transformation
virtual	~Transformation ()=default
virtual void	set_report (PassReportConsumer *report)
	Set the report consumer for transformation feedback.
virtual bool	try_apply (builder::StructuredSDFGBuilder &builder, analysis::AnalysisManager &analysis_manager)
	Attempt to apply the transformation if possible.

Static Public Member Functions
static std::set< std::string >	copied_in_buffers (const Function &function, structured_control_flow::ControlFlowNode &root)
	The async-stageable buffers the copy-in nodes under root fill: the containers a pipeline would multi-buffer.
static std::vector< structured_control_flow::StructuredLoop * >	staging_panels (const Function &function, structured_control_flow::ControlFlowNode &root)
	The candidate panel loops under root this transformation can target.
static SoftwarePipelining	from_json (builder::StructuredSDFGBuilder &builder, const nlohmann::json &j)

Additional Inherited Members
Protected Attributes inherited from sdfg::transformations::Transformation
PassReportConsumer *	report_ = nullptr

Detailed Description

Software-pipeline a sequential panel loop that cooperatively stages a shared-memory tile each iteration (the structure LocalStorage emits).

Targets a sequential loop whose body is [ barrier; cooperative-copy(global -> shared); barrier; compute(reads shared) ] and rewrites it into an stages -deep pipeline so the next panel's global load (issued via cp.async) overlaps the current panel's compute:

prologue: async-copy panel 0 -> buf[0]; commit for p in [0, n): if p + stages-1 < n: async-copy panel p+stages-1 -> buf[(p+stages-1)stages]; commit wait_prior(stages-1); barrier compute from buf[p % stages]

The staged buffer gains a leading [stages] axis indexed by p % stages. The staging copy's tiles::TileCopyNode has its atom flipped to cp.async (its plan offset biased per stage) and gains a PipelineCommitNode; a PipelineWaitNode fences each panel's reads. Only fires inside a map whose tile target supports asynchronous staging of the copied-in buffers (tiles::TileTarget::supports_async_staging; on GPUs the shared tier), on a compile-time-constant panel count >= stages; buffers written by the compute stay single-buffered.

Constructor & Destructor Documentation

SoftwarePipelining()

sdfg::transformations::SoftwarePipelining::SoftwarePipelining ( structured_control_flow::StructuredLoop & loop, size_t stages = 2, bool single_operand = false, bool register_staged = false )

explicit

Member Function Documentation

apply()

virtual void sdfg::transformations::SoftwarePipelining::apply ( builder::StructuredSDFGBuilder & builder, analysis::AnalysisManager & analysis_manager )

overridevirtual

Apply this transformation to the SDFG.

Parameters

builder	The SDFG builder
analysis_manager	The analysis manager (may be invalidated)

Implements sdfg::transformations::Transformation.

can_be_applied()

virtual bool sdfg::transformations::SoftwarePipelining::can_be_applied ( builder::StructuredSDFGBuilder & builder, analysis::AnalysisManager & analysis_manager )

overridevirtual

Check if this transformation can be safely applied.

Parameters

builder	The SDFG builder
analysis_manager	The analysis manager providing necessary analyses

Returns

true if all preconditions are met

Implements sdfg::transformations::Transformation.

copied_in_buffers()

std::set< std::string > sdfg::transformations::SoftwarePipelining::copied_in_buffers ( const Function & function, structured_control_flow::ControlFlowNode & root )

static

The async-stageable buffers the copy-in nodes under root fill: the containers a pipeline would multi-buffer.

Empty when root stages nothing (so it is not a pipelineable panel).

A buffer qualifies when a cooperative tiles::TileCopyNode copies into it (its _dst pointer) and the enclosing map's tile target can asynchronously multi-buffer its storage (tiles::TileTarget::supports_async_staging; on GPUs the shared tier). This is the single source of truth for "which buffers get staged", shared by can_be_applied, apply, and search spaces.

from_json()

SoftwarePipelining sdfg::transformations::SoftwarePipelining::from_json ( builder::StructuredSDFGBuilder & builder, const nlohmann::json & j )

static

name()

virtual std::string sdfg::transformations::SoftwarePipelining::name ( ) const

overridevirtual

Get the name of this transformation.

Returns

The transformation name (e.g., "LoopInterchange")

Implements sdfg::transformations::Transformation.

staging_panels()

std::vector< structured_control_flow::StructuredLoop * > sdfg::transformations::SoftwarePipelining::staging_panels ( const Function & function, structured_control_flow::ControlFlowNode & root )

static

The candidate panel loops under root this transformation can target.

A panel is the nearest loop enclosing a cooperative copy-in (a tiles::TileCopyNode that LocalStorage emits) that fills a buffer the loop's enclosing tile target can asynchronously multi-buffer (tiles::TileTarget::supports_async_staging; on GPUs the shared tier). Only sequential loops qualify: a copy-in sitting directly in a parallel Map has no cross-iteration order to pipeline, so it nominates no panel. Returned in first-appearance order. This is the single source of truth for "what can be pipelined", so a search space can enumerate candidates without re-deriving the scan.

to_json()

virtual void sdfg::transformations::SoftwarePipelining::to_json ( nlohmann::json & j ) const

overridevirtual

Serialize this transformation to JSON.

Parameters

j	JSON object to populate with transformation description

Exceptions

std::logic_error

if not implemented

Implements sdfg::transformations::Transformation.

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

• opt/include/sdfg/tiles/transformations/software_pipelining.h