circt::synth::CutRewritePattern Struct Reference

Base class for cut rewriting patterns used in combinational logic optimization. More...

#include <CutRewriter.h>

Inheritance diagram for circt::synth::CutRewritePattern:

Collaboration diagram for circt::synth::CutRewritePattern:

Public Member Functions
	CutRewritePattern (mlir::MLIRContext *context)
virtual	~CutRewritePattern ()=default
	Virtual destructor for base class.
virtual bool	match (const Cut &cut) const =0
	Check if a cut matches this pattern.
virtual bool	useTruthTableMatcher (SmallVectorImpl< NPNClass > &matchingNPNClasses) const
	Specify truth tables that this pattern can match.
virtual FailureOr< Operation * >	rewrite (mlir::OpBuilder &builder, Cut &cut) const =0
	Return a new operation that replaces the matched cut.
virtual double	getArea () const =0
	Get the area cost of this pattern.
virtual DelayType	getDelay (unsigned inputIndex, unsigned outputIndex) const =0
	Get the delay between specific input and output.
virtual unsigned	getNumOutputs () const =0
	Get the number of outputs this pattern produces.
virtual StringRef	getPatternName () const
	Get the name of this pattern. Used for debugging.
virtual LocationAttr	getLoc () const
	Get location for this pattern(optional).
mlir::MLIRContext *	getContext () const

Private Attributes
mlir::MLIRContext *	context

Detailed Description

Base class for cut rewriting patterns used in combinational logic optimization.

A CutRewritePattern represents a library component or optimization pattern that can replace cuts in the combinational logic network. Each pattern defines:

• How to recognize matching cuts
• How to transform/replace the matched cuts
• Area and timing characteristics

Patterns can use truth table matching for efficient recognition or implement custom matching logic for more complex cases.

Definition at line 332 of file CutRewriter.h.

Constructor & Destructor Documentation

CutRewritePattern()

circt::synth::CutRewritePattern::CutRewritePattern ( mlir::MLIRContext *  context )

inline

Definition at line 333 of file CutRewriter.h.

~CutRewritePattern()

virtual circt::synth::CutRewritePattern::~CutRewritePattern ( )

virtualdefault

Virtual destructor for base class.

Member Function Documentation

getArea()

virtual double circt::synth::CutRewritePattern::getArea ( ) const

pure virtual

Get the area cost of this pattern.

Implemented in GenericLUT, and TechLibraryPattern.

Referenced by circt::synth::MatchedPattern::getArea(), and circt::synth::CutRewriter::patternMatchCut().

getContext()

mlir::MLIRContext * circt::synth::CutRewritePattern::getContext ( ) const

inline

Definition at line 384 of file CutRewriter.h.

References context.

getDelay()

virtual DelayType circt::synth::CutRewritePattern::getDelay ( unsigned  inputIndex, unsigned  outputIndex  ) const

pure virtual

Get the delay between specific input and output.

NOTE: The input index is already permuted according to the pattern's input permutation, so it's not necessary to account for it here.

Implemented in GenericLUT, and TechLibraryPattern.

Referenced by circt::synth::MatchedPattern::getDelay().

getLoc()

virtual LocationAttr circt::synth::CutRewritePattern::getLoc ( ) const

inlinevirtual

Get location for this pattern(optional).

Reimplemented in TechLibraryPattern.

Definition at line 382 of file CutRewriter.h.

References context.

getNumOutputs()

virtual unsigned circt::synth::CutRewritePattern::getNumOutputs ( ) const

pure virtual

Get the number of outputs this pattern produces.

Implemented in GenericLUT, and TechLibraryPattern.

getPatternName()

virtual StringRef circt::synth::CutRewritePattern::getPatternName ( ) const

inlinevirtual

Get the name of this pattern. Used for debugging.

Reimplemented in GenericLUT, and TechLibraryPattern.

Definition at line 379 of file CutRewriter.h.

match()

virtual bool circt::synth::CutRewritePattern::match ( const Cut &  cut ) const

pure virtual

Check if a cut matches this pattern.

This method is called to determine if a cut can be replaced by this pattern. If useTruthTableMatcher() returns true, this method is only called for cuts with matching truth tables.

Implemented in GenericLUT, and TechLibraryPattern.

rewrite()

virtual FailureOr< Operation * > circt::synth::CutRewritePattern::rewrite ( mlir::OpBuilder &  builder, Cut &  cut  ) const

pure virtual

Return a new operation that replaces the matched cut.

Unlike MLIR's RewritePattern framework which allows arbitrary in-place modifications, this method creates a new operation to replace the matched cut rather than modifying existing operations. This constraint exists because the cut enumerator maintains references to operations throughout the circuit, making it safe to only replace the root operation of each cut while preserving all other operations unchanged.

Implemented in TechLibraryPattern, and GenericLUT.

useTruthTableMatcher()

bool CutRewritePattern::useTruthTableMatcher ( SmallVectorImpl< NPNClass > &  matchingNPNClasses ) const

virtual

Specify truth tables that this pattern can match.

If this method returns true, the pattern matcher will use truth table comparison for efficient pre-filtering. Only cuts with matching truth tables will be passed to the match() method. If it returns false, the pattern will be checked against all cuts regardless of their truth tables. This is useful for patterns that match regardless of their truth tables, such as LUT-based patterns.

Reimplemented in TechLibraryPattern.

Definition at line 619 of file CutRewriter.cpp.

Member Data Documentation

context

mlir::MLIRContext* circt::synth::CutRewritePattern::context

private

Definition at line 387 of file CutRewriter.h.

Referenced by getContext(), and getLoc().

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The documentation for this struct was generated from the following files:

• /home/runner/work/circt-www/circt-www/circt_src/include/circt/Dialect/Synth/Transforms/CutRewriter.h
• /home/runner/work/circt-www/circt-www/circt_src/lib/Dialect/Synth/Transforms/CutRewriter.cpp