Classes
class	CombinationalVisitor
	This helps visit Combinational nodes. More...

Functions
KnownBits	computeKnownBits (Value value)
	Compute "known bits" information about the specified value - the set of bits that are guaranteed to always be zero, and the set of bits that are guaranteed to always be one (these must be exclusive!).

Value	createZExt (OpBuilder &builder, Location loc, Value value, unsigned targetWidth)
	Create the ops to zero-extend a value to an integer of equal or larger type.

Value	createOrFoldSExt (Location loc, Value value, Type destTy, OpBuilder &builder)
	Create a sign extension operation from a value of integer type to an equal or larger integer type.

Value	createOrFoldSExt (Value value, Type destTy, ImplicitLocOpBuilder &builder)

Value	createOrFoldNot (Location loc, Value value, OpBuilder &builder, bool twoState=false)
	Create a `‘Not’' gate on a value.

Value	createOrFoldNot (Value value, ImplicitLocOpBuilder &builder, bool twoState=false)

void	extractBits (OpBuilder &builder, Value val, SmallVectorImpl< Value > &bits)
	Extract bits from a value.

Value	constructMuxTree (OpBuilder &builder, Location loc, ArrayRef< Value > selectors, ArrayRef< Value > leafNodes, Value outOfBoundsValue)
	Construct a mux tree for given leaf nodes.

Value	createDynamicExtract (OpBuilder &builder, Location loc, Value value, Value offset, unsigned width)
	Extract a range of bits from an integer at a dynamic offset.

Value	createDynamicInject (OpBuilder &builder, Location loc, Value value, Value offset, Value replacement, bool twoState=false)
	Replace a range of bits in an integer at a dynamic offset, and return the updated integer value.

Value	createInject (OpBuilder &builder, Location loc, Value value, unsigned offset, Value replacement)
	Replace a range of bits in an integer and return the updated integer value.

std::pair< Value, Value >	fullAdder (OpBuilder &builder, Location loc, Value a, Value b, Value c)
	Construct a full adder for three 1-bit inputs.

SmallVector< Value >	wallaceReduction (OpBuilder &builder, Location loc, size_t width, size_t targetAddends, SmallVector< SmallVector< Value > > &addends)
	Perform Wallace tree reduction on partial products.

void	populateCombNarrowingPatterns (mlir::RewritePatternSet &patterns, mlir::DataFlowSolver &solver)
	Add patterns for int range based narrowing.

Function Documentation

◆ computeKnownBits()

KnownBits circt::comb::computeKnownBits ( Value value )

Compute "known bits" information about the specified value - the set of bits that are guaranteed to always be zero, and the set of bits that are guaranteed to always be one (these must be exclusive!).

Given an integer SSA value, check to see if we know anything about the result of the computation.

A bit that exists in neither set is unknown.

For example, we know that "and with a constant" always returns zeros for the zero bits in a constant.

Definition at line 87 of file CombAnalysis.cpp.

◆ constructMuxTree()

Value circt::comb::constructMuxTree	(	OpBuilder &	builder,
		Location	loc,
		ArrayRef< Value >	selectors,
		ArrayRef< Value >	leafNodes,
		Value	outOfBoundsValue
	)

Construct a mux tree for given leaf nodes.

selectors is the selector for each level of the tree. Currently the selector is tested from MSB to LSB.

Definition at line 104 of file CombOps.cpp.

◆ createDynamicExtract()

Value circt::comb::createDynamicExtract	(	OpBuilder &	builder,
		Location	loc,
		Value	value,
		Value	offset,
		unsigned	width
	)

Extract a range of bits from an integer at a dynamic offset.

Definition at line 131 of file CombOps.cpp.

References assert(), and createZExt().

◆ createDynamicInject()

Value circt::comb::createDynamicInject	(	OpBuilder &	builder,
		Location	loc,
		Value	value,
		Value	offset,
		Value	replacement,
		bool	twoState = `false`
	)

Replace a range of bits in an integer at a dynamic offset, and return the updated integer value.

Calls createInject if the offset is constant.

Definition at line 151 of file CombOps.cpp.

References assert(), hw.ConstantOp::create(), createInject(), createOrFoldNot(), and createZExt().

◆ createInject()

Value circt::comb::createInject	(	OpBuilder &	builder,
		Location	loc,
		Value	value,
		unsigned	offset,
		Value	replacement
	)

Replace a range of bits in an integer and return the updated integer value.

Definition at line 186 of file CombOps.cpp.

References assert(), and comb.ExtractOp::create().

Referenced by createDynamicInject().

◆ createOrFoldNot() [1/2]

Value circt::comb::createOrFoldNot	(	Location	loc,
		Value	value,
		OpBuilder &	builder,
		bool	twoState = `false`
	)

Create a `‘Not’' gate on a value.

Definition at line 65 of file CombOps.cpp.

References hw.ConstantOp::create().

Referenced by circt::scftocalyx::BuildOpGroups::buildFpIntTypeCastOp(), circt::scftocalyx::BuildOpGroups::buildLibraryBinaryPipeOp(), circt::scftocalyx::BuildOpGroups::buildOp(), ConvertCellOp::convertPipelineOp(), ConvertCellOp::convertPrimitiveOp(), createDynamicInject(), createOrFoldNot(), and foldCommonMuxValue().

◆ createOrFoldNot() [2/2]

Value circt::comb::createOrFoldNot	(	Value	value,
		ImplicitLocOpBuilder &	builder,
		bool	twoState = `false`
	)

Definition at line 71 of file CombOps.cpp.

References createOrFoldNot().

◆ createOrFoldSExt() [1/2]

Value circt::comb::createOrFoldSExt	(	Location	loc,
		Value	value,
		Type	destTy,
		OpBuilder &	builder
	)

Create a sign extension operation from a value of integer type to an equal or larger integer type.

Definition at line 42 of file CombOps.cpp.

References assert().

Referenced by ConvertCellOp::convertPrimitiveOp(), and createOrFoldSExt().

◆ createOrFoldSExt() [2/2]

Value circt::comb::createOrFoldSExt	(	Value	value,
		Type	destTy,
		ImplicitLocOpBuilder &	builder
	)

Definition at line 60 of file CombOps.cpp.

References createOrFoldSExt().

◆ createZExt()

Value circt::comb::createZExt	(	OpBuilder &	builder,
		Location	loc,
		Value	value,
		unsigned	targetWidth
	)

Create the ops to zero-extend a value to an integer of equal or larger type.

Definition at line 24 of file CombOps.cpp.

References assert(), and hw.ConstantOp::create().

Referenced by createDynamicExtract(), and createDynamicInject().

◆ extractBits()

void circt::comb::extractBits	(	OpBuilder &	builder,
		Value	val,
		SmallVectorImpl< Value > &	bits
	)

Extract bits from a value.

Definition at line 77 of file CombOps.cpp.

References assert(), and concat().

◆ fullAdder()

std::pair< Value, Value > circt::comb::fullAdder	(	OpBuilder &	builder,
		Location	loc,
		Value	a,
		Value	b,
		Value	c
	)

Construct a full adder for three 1-bit inputs.

Definition at line 221 of file CombOps.cpp.

◆ populateCombNarrowingPatterns()

void circt::comb::populateCombNarrowingPatterns	(	mlir::RewritePatternSet &	patterns,
		mlir::DataFlowSolver &	solver
	)

Add patterns for int range based narrowing.

◆ wallaceReduction()

SmallVector< Value > circt::comb::wallaceReduction	(	OpBuilder &	builder,
		Location	loc,
		size_t	width,
		size_t	targetAddends,
		SmallVector< SmallVector< Value > > &	addends
	)

Perform Wallace tree reduction on partial products.

See https://en.wikipedia.org/wiki/Wallace_tree

Parameters

targetAddends	The number of addends to reduce to (2 for carry-save).
inputAddends	The rows of bits to be summed.

Definition at line 238 of file CombOps.cpp.