sdfg::transformations::LoopInterchange Class Reference

Loop interchange transformation that swaps two nested loops. More...

#include <sdfg/transformations/loop_interchange.h>

Inheritance diagram for sdfg::transformations::LoopInterchange:

Public Member Functions
	LoopInterchange (structured_control_flow::StructuredLoop &outer_loop, structured_control_flow::StructuredLoop &inner_loop)
	Construct a loop interchange transformation.
virtual std::string	name () const override
	Get the name of this transformation.
LoopSwap	proposal (analysis::AnalysisManager *analysis_manager=nullptr) const
	Compute the interchanged loop headers without modifying the SDFG.
virtual bool	can_be_applied (builder::StructuredSDFGBuilder &builder, analysis::AnalysisManager &analysis_manager) override
	Check if this transformation can be applied.
virtual void	apply (builder::StructuredSDFGBuilder &builder, analysis::AnalysisManager &analysis_manager) override
	Apply the loop interchange transformation.
virtual void	to_json (nlohmann::json &j) const override
	Serialize this transformation to JSON.
structured_control_flow::StructuredLoop *	new_outer_loop () const
structured_control_flow::StructuredLoop *	new_inner_loop () const
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 LoopInterchange	from_json (builder::StructuredSDFGBuilder &builder, const nlohmann::json &j)
	Deserialize a loop interchange transformation from JSON.

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

Detailed Description

Loop interchange transformation that swaps two nested loops.

This transformation swaps the order of two nested loops (outer and inner), potentially improving data locality and parallelization opportunities. The transformation preserves the computational semantics while reordering loop execution.

Supports two cases:

• Independent bounds: inner loop bounds do not reference the outer induction variable. The loop headers are simply swapped.
• Dependent bounds (Fourier-Motzkin): inner loop bounds are min/max of affine terms in the outer induction variable with non-negative coefficients. The new outer range is spanned by the first and last outer iteration; the new inner range inverts each affine term, rounded onto the outer loop's stride lattice.

Note

The outer loop must have exactly one child (the inner loop)

For-For interchange is checked via dependence analysis (delta sets must remain lex-non-negative)

Constructor & Destructor Documentation

LoopInterchange()

sdfg::transformations::LoopInterchange::LoopInterchange	(	structured_control_flow::StructuredLoop &	outer_loop,
		structured_control_flow::StructuredLoop &	inner_loop )

Construct a loop interchange transformation.

Parameters

outer_loop	The outer loop to be interchanged
inner_loop	The inner loop to be interchanged

Member Function Documentation

apply()

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

overridevirtual

Apply the loop interchange transformation.

Parameters

builder	The SDFG builder
analysis_manager	The analysis manager

Implements sdfg::transformations::Transformation.

can_be_applied()

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

overridevirtual

Check if this transformation can be applied.

Parameters

builder	The SDFG builder
analysis_manager	The analysis manager

Returns

true if the transformation can be applied safely

Implements sdfg::transformations::Transformation.

from_json()

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

static

Deserialize a loop interchange transformation from JSON.

Parameters

builder	The SDFG builder
j	JSON description of the transformation

Returns

The deserialized transformation

name()

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

overridevirtual

Get the name of this transformation.

Returns

"LoopInterchange"

Implements sdfg::transformations::Transformation.

new_inner_loop()

structured_control_flow::StructuredLoop * sdfg::transformations::LoopInterchange::new_inner_loop

(

)

const

new_outer_loop()

structured_control_flow::StructuredLoop * sdfg::transformations::LoopInterchange::new_outer_loop

(

)

const

proposal()

LoopSwap sdfg::transformations::LoopInterchange::proposal

(

analysis::AnalysisManager *

analysis_manager = nullptr

)

const

Compute the interchanged loop headers without modifying the SDFG.

Includes bound projection and inversion for dependent loops. Shared by the reduction-footprint preview and apply(); does not check dependence legality.

Parameters

analysis_manager

Optional; enables floor-division bounds whose numerator is provably non-negative

Returns

Original loop IDs and the proposed outer and inner headers

to_json()

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

overridevirtual

Serialize this transformation to JSON.

Parameters

j	JSON object to populate

Implements sdfg::transformations::Transformation.

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

• opt/include/sdfg/transformations/loop_interchange.h