A strategy for applying type casts. More...

#include <cast.hh>

Inheritance diagram for ghidra::CastStrategy:

Public Types
enum	IntPromotionCode { NO_PROMOTION = -1, UNKNOWN_PROMOTION = 0, UNSIGNED_EXTENSION = 1, SIGNED_EXTENSION = 2, EITHER_EXTENSION = 3 }
	Types of integer promotion. More...

Public Member Functions
	CastStrategy (void)
	Constructor.

void	setTypeFactory (TypeFactory *t)
	Establish the data-type factory. More...

virtual	~CastStrategy (void)
	Destructor.

virtual int4	localExtensionType (const Varnode vn, const PcodeOp op) const =0
	Decide on integer promotion by examining just local properties of the given Varnode. More...

virtual int4	intPromotionType (const Varnode *vn) const =0
	Calculate the integer promotion code of a given Varnode. More...

virtual bool	checkIntPromotionForCompare (const PcodeOp *op, int4 slot) const =0
	Check if integer promotion forces a cast for the given comparison op and slot. More...

virtual bool	checkIntPromotionForExtension (const PcodeOp *op) const =0
	Check if integer promotion forces a cast for the input to the given extension. More...

virtual bool	isExtensionCastImplied (const PcodeOp op, const PcodeOp readOp) const =0
	Is the given ZEXT/SEXT cast implied by the expression its in? More...

virtual Datatype *	castStandard (Datatype reqtype, Datatype curtype, bool care_uint_int, bool care_ptr_uint) const =0
	Does there need to be a visible cast between the given data-types. More...

virtual Datatype *	arithmeticOutputStandard (const PcodeOp *op)=0
	What is the output data-type produced by the given integer arithmetic operation. More...

virtual bool	isSubpieceCast (Datatype outtype, Datatype intype, uint4 offset) const =0
	Is truncating an input data-type, producing an output data-type, considered a cast. More...

virtual bool	isSubpieceCastEndian (Datatype outtype, Datatype intype, uint4 offset, bool isbigend) const =0
	Is the given data-type truncation considered a cast, given endianess concerns. More...

virtual bool	isSextCast (Datatype outtype, Datatype intype) const =0
	Is sign-extending an input data-type, producing an output data-type, considered a cast. More...

virtual bool	isZextCast (Datatype outtype, Datatype intype) const =0
	Is zero-extending an input data-type, producing an output data-type, considered a cast. More...

bool	markExplicitUnsigned (PcodeOp *op, int4 slot) const
	Check if a constant input should be explicitly labeled as an unsigned token. More...

bool	markExplicitLongSize (PcodeOp *op, int4 slot) const
	Check is a constant input should be explicitly labeled as a long integer token. More...

bool	caresAboutCharRepresentation (const Varnode vn, const PcodeOp op) const
	For the given PcodeOp, does it matter if a constant operand is presented as a character or integer. More...

Protected Attributes
TypeFactory *	tlst
	Type factory associated with the Architecture.

int4	promoteSize
	Size of int data-type, (size that integers get promoted to)

Detailed Description

A strategy for applying type casts.

A cast operation in C or other languages masks a variety of possible low-level conversions, such as extensions, truncations, integer to floating-point, etc. On top of this, languages allow many of these types of operations to be implied in the source code, with no explicit token representing the conversion. Conversions happen automatically for things like integer promotion, between different sizes (of integers), and between signed and unsigned data-type variants.

This class is the API for making four kinds of decisions:

Do we need a cast operator for a given assignment
Does the given conversion operation need to be represented as a cast
Does the given extension or comparison match with the expected level of integer promotion
What data-type is produced by a particular integer arithmetic operation

Member Enumeration Documentation

◆ IntPromotionCode

enum ghidra::CastStrategy::IntPromotionCode

Types of integer promotion.

For many languages, small integers are automatically promoted to a standard size. The decompiler describes how an expression is or will be affected by integer promotion, using these codes

Enumerator
NO_PROMOTION	There is no integer promotion.
UNKNOWN_PROMOTION	The type of integer promotion cannot be determined.
UNSIGNED_EXTENSION	The value is promoted using unsigned extension.
SIGNED_EXTENSION	The value is promoted using signed extension.
EITHER_EXTENSION	The value is promoted using either signed or unsigned extension.

Member Function Documentation

◆ arithmeticOutputStandard()

virtual Datatype* ghidra::CastStrategy::arithmeticOutputStandard ( const PcodeOp * op )

pure virtual

What is the output data-type produced by the given integer arithmetic operation.

Parameters

op	is the given operation

Returns: the output data-type

Implemented in ghidra::CastStrategyC.

Referenced by ghidra::TypeOpIntAdd::getOutputToken(), ghidra::TypeOpIntSub::getOutputToken(), ghidra::TypeOpInt2Comp::getOutputToken(), ghidra::TypeOpIntNegate::getOutputToken(), ghidra::TypeOpIntXor::getOutputToken(), ghidra::TypeOpIntAnd::getOutputToken(), ghidra::TypeOpIntOr::getOutputToken(), ghidra::TypeOpIntMult::getOutputToken(), and ~CastStrategy().

◆ caresAboutCharRepresentation()

bool ghidra::CastStrategy::caresAboutCharRepresentation	(	const Varnode *	vn,
		const PcodeOp *	op
	)		const

inline

For the given PcodeOp, does it matter if a constant operand is presented as a character or integer.

In most languages, character constants are promoted to integers as a matter of course, so it doesn't matter if the constant is represented as an integer (a string of digits) or a character (surrounded by quotes). But its possible that a particular operator does care. If the operator needs an explicit character representation for an operand with a character data-type, return true.

Parameters

vn	is the constant with character data-type
op	is the given PcodeOp which reads the constant (may be null)

Returns: true if the constant must be represented as an explicit character

Referenced by ghidra::PrintC::pushCharConstant().

◆ castStandard()

virtual Datatype* ghidra::CastStrategy::castStandard	(	Datatype *	reqtype,
		Datatype *	curtype,
		bool	care_uint_int,
		bool	care_ptr_uint
	)		const

pure virtual

Does there need to be a visible cast between the given data-types.

The cast is from a current data-type to an expected data-type. NULL is returned if no cast is required, otherwise the data-type to cast to (usually the expected data-type) is returned.

Parameters

reqtype	is the expected data-type
curtype	is the current data-type
care_uint_int	is true if we care about a change in signedness
care_ptr_uint	is true if we care about conversions between pointers and unsigned values

Returns: NULL to indicate no cast, or the data-type to cast to

Implemented in ghidra::CastStrategyJava, and ghidra::CastStrategyC.

◆ checkIntPromotionForCompare()

virtual bool ghidra::CastStrategy::checkIntPromotionForCompare	(	const PcodeOp *	op,
		int4	slot
	)		const

pure virtual

Check if integer promotion forces a cast for the given comparison op and slot.

Compute to what level the given slot has seen integer promotion and if a cast is required before the comparison operator makes sense.

Parameters

op	is the given comparison operator
slot	is the input slot being tested

Returns: true if a cast is required before comparing

Implemented in ghidra::CastStrategyC.

Referenced by ghidra::TypeOpEqual::getInputCast(), ghidra::TypeOpNotEqual::getInputCast(), ghidra::TypeOpIntSless::getInputCast(), ghidra::TypeOpIntSlessEqual::getInputCast(), ghidra::TypeOpIntLess::getInputCast(), ghidra::TypeOpIntLessEqual::getInputCast(), and ~CastStrategy().

◆ checkIntPromotionForExtension()

virtual bool ghidra::CastStrategy::checkIntPromotionForExtension ( const PcodeOp * op ) const

pure virtual

Check if integer promotion forces a cast for the input to the given extension.

Compute to what level the given slot has seen integer promotion and if a cast is required before the extension operator makes sense.

Parameters

op	is the given extension operator INT_ZEXT or INT_SEXT

Returns: true if a cast is required before extending

Implemented in ghidra::CastStrategyC.

Referenced by ghidra::TypeOpIntZext::getInputCast(), ghidra::TypeOpIntSext::getInputCast(), and ~CastStrategy().

◆ intPromotionType()

virtual int4 ghidra::CastStrategy::intPromotionType ( const Varnode * vn ) const

pure virtual

Calculate the integer promotion code of a given Varnode.

Recursively examine the expression defining the Varnode as necessary

Parameters

vn	is the given Varnode

Returns: the IntPromotionCode

Implemented in ghidra::CastStrategyC.

Referenced by ghidra::CastStrategyC::checkIntPromotionForCompare(), ghidra::CastStrategyC::checkIntPromotionForExtension(), ghidra::TypeOpIntRight::getInputCast(), ghidra::TypeOpIntSright::getInputCast(), ghidra::TypeOpIntDiv::getInputCast(), ghidra::TypeOpIntSdiv::getInputCast(), ghidra::TypeOpIntRem::getInputCast(), ghidra::TypeOpIntSrem::getInputCast(), and ~CastStrategy().

◆ isExtensionCastImplied()

virtual bool ghidra::CastStrategy::isExtensionCastImplied	(	const PcodeOp *	op,
		const PcodeOp *	readOp
	)		const

pure virtual

Is the given ZEXT/SEXT cast implied by the expression its in?

We've already determined that the given ZEXT or SEXT op can be viewed as a natural cast operation. Determine if the cast is implied by the expression its and doesn't need to be printed.

Parameters

op	is the given ZEXT or SEXT PcodeOp
readOp	is the PcodeOp consuming the output of the extensions (or null)

Returns: true if the op as a cast does not need to be printed

Implemented in ghidra::CastStrategyC.

Referenced by ghidra::PrintC::opIntSext(), ghidra::PrintC::opIntZext(), and ~CastStrategy().

◆ isSextCast()

virtual bool ghidra::CastStrategy::isSextCast	(	Datatype *	outtype,
		Datatype *	intype
	)		const

pure virtual

Is sign-extending an input data-type, producing an output data-type, considered a cast.

Data-types must be provided from the input and output of an INT_SEXT operation.

Parameters

outtype	is the output data-type
intype	is the input data-type

Returns: true if the INT_SEXT should be represented as a cast

Implemented in ghidra::CastStrategyC.

Referenced by ghidra::PrintC::opIntSext(), and ~CastStrategy().

◆ isSubpieceCast()

virtual bool ghidra::CastStrategy::isSubpieceCast	(	Datatype *	outtype,
		Datatype *	intype,
		uint4	offset
	)		const

pure virtual

Is truncating an input data-type, producing an output data-type, considered a cast.

Data-types must be provided from the input and output of a SUBPIECE operation.

Parameters

outtype	is the output data-type
intype	is the input data-type
offset	is number of bytes truncated by the SUBPIECE

Returns: true if the SUBPIECE should be represented as a cast

Implemented in ghidra::CastStrategyC.

Referenced by ghidra::CastStrategyC::isSubpieceCastEndian(), ghidra::PrintC::opSubpiece(), and ~CastStrategy().

◆ isSubpieceCastEndian()

virtual bool ghidra::CastStrategy::isSubpieceCastEndian	(	Datatype *	outtype,
		Datatype *	intype,
		uint4	offset,
		bool	isbigend
	)		const

pure virtual

Is the given data-type truncation considered a cast, given endianess concerns.

This is equivalent to isSubpieceCast() but where the truncation is accomplished by pulling bytes directly out of memory. We assume the input data-type is layed down in memory, and we pull the output value starting at a given byte offset.

Parameters

outtype	is the output data-type
intype	is the input data-type
offset	is the given byte offset (into the input memory)
isbigend	is true if the address space holding the memory is big endian.

Returns: true if the truncation should be represented as a cast

Implemented in ghidra::CastStrategyC.

Referenced by ghidra::PrintC::pushPartialSymbol(), and ~CastStrategy().

◆ isZextCast()

virtual bool ghidra::CastStrategy::isZextCast	(	Datatype *	outtype,
		Datatype *	intype
	)		const

pure virtual

Is zero-extending an input data-type, producing an output data-type, considered a cast.

Data-types must be provided from the input and output of an INT_ZEXT operation.

Parameters

outtype	is the output data-type
intype	is the input data-type

Returns: true if the INT_ZEXT should be represented as a cast

Implemented in ghidra::CastStrategyJava, and ghidra::CastStrategyC.

Referenced by ghidra::PrintC::opIntZext(), and ~CastStrategy().

◆ localExtensionType()

virtual int4 ghidra::CastStrategy::localExtensionType	(	const Varnode *	vn,
		const PcodeOp *	op
	)		const

pure virtual

Decide on integer promotion by examining just local properties of the given Varnode.

Parameters

vn	is the given Varnode
op	is the PcodeOp reading the Varnode

Returns: an IntPromotionCode (excluding NO_PROMOTION)

Implemented in ghidra::CastStrategyC.

Referenced by ghidra::CastStrategyC::intPromotionType(), and ~CastStrategy().

◆ markExplicitLongSize()

bool ghidra::CastStrategy::markExplicitLongSize	(	PcodeOp *	op,
		int4	slot
	)		const

Check is a constant input should be explicitly labeled as a long integer token.

This method checks if the indicated input is an integer constant that needs to be coerced (as a source token) into a data-type that is larger than the base integer. If this is true, the input Varnode is marked for printing as explicitly a larger integer (typically long).

Parameters

op	is the PcodeOp taking the value as input
slot	is the input slot of the value

Returns: true if the Varnode gets marked for printing

References ghidra::Varnode::getHigh(), ghidra::PcodeOp::getIn(), ghidra::Datatype::getMetatype(), ghidra::Varnode::getOffset(), ghidra::PcodeOp::getOpcode(), ghidra::Varnode::getSize(), ghidra::HighVariable::getType(), ghidra::Varnode::isConstant(), ghidra::TypeOp::isShiftOp(), promoteSize, ghidra::Varnode::setLongPrint(), ghidra::TYPE_INT, ghidra::TYPE_UINT, and ghidra::TYPE_UNKNOWN.

Referenced by ghidra::ActionSetCasts::castInput(), and ~CastStrategy().

◆ markExplicitUnsigned()

bool ghidra::CastStrategy::markExplicitUnsigned	(	PcodeOp *	op,
		int4	slot
	)		const

Check if a constant input should be explicitly labeled as an unsigned token.

Many languages can mark an integer constant as explicitly unsigned. When the decompiler is deciding on cast operations, this is one of the checks it performs. This method checks if the indicated input is an integer constant that needs to be coerced (as a source token) into being unsigned. If this is true, the input Varnode is marked for printing as explicitly unsigned.

Parameters

op	is the PcodeOp taking the value as input
slot	is the input slot of the value

Returns: true if the Varnode gets marked for printing

References ghidra::Varnode::getHighTypeReadFacing(), ghidra::PcodeOp::getIn(), ghidra::Datatype::getMetatype(), ghidra::PcodeOp::getOpcode(), ghidra::PcodeOp::getOut(), ghidra::TypeOp::inheritsSign(), ghidra::TypeOp::inheritsSignFirstParamOnly(), ghidra::Datatype::isCharPrint(), ghidra::Varnode::isConstant(), ghidra::Datatype::isEnumType(), ghidra::Varnode::isExplicit(), ghidra::Varnode::loneDescend(), ghidra::PcodeOp::numInput(), ghidra::Varnode::setUnsignedPrint(), ghidra::TYPE_UINT, and ghidra::TYPE_UNKNOWN.

Referenced by ghidra::ActionSetCasts::castInput(), and ~CastStrategy().

◆ setTypeFactory()

void ghidra::CastStrategy::setTypeFactory ( TypeFactory * t )

Establish the data-type factory.

Sets the TypeFactory used to produce data-types for the arithmeticOutputStandard() method

Parameters

t	is the TypeFactory

References ghidra::TypeFactory::getSizeOfInt(), promoteSize, and tlst.

Referenced by CastStrategy(), and ghidra::PrintC::initializeFromArchitecture().

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

cast.hh
cast.cc

Public Types

Public Member Functions

Protected Attributes

Detailed Description

Member Enumeration Documentation

◆ IntPromotionCode

Member Function Documentation

◆ arithmeticOutputStandard()

◆ caresAboutCharRepresentation()

◆ castStandard()

◆ checkIntPromotionForCompare()

◆ checkIntPromotionForExtension()

◆ intPromotionType()

◆ isExtensionCastImplied()

◆ isSextCast()

◆ isSubpieceCast()

◆ isSubpieceCastEndian()

◆ isZextCast()

◆ localExtensionType()

◆ markExplicitLongSize()

◆ markExplicitUnsigned()

◆ setTypeFactory()