A strategy for applying type casts. More...

#include <cast.hh>

Inheritance diagram for 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 =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...

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

enum 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

virtual Datatype* 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 CastStrategyC.

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

virtual Datatype* 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 CastStrategyJava, and CastStrategyC.

virtual bool 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 CastStrategyC.

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

virtual bool 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 CastStrategyC.

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

virtual int4 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 CastStrategyC.

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

virtual bool 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 CastStrategyC.

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

virtual bool 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 CastStrategyC.

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

virtual bool 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 CastStrategyC.

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

virtual bool 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 CastStrategyC.

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

virtual bool 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 CastStrategyJava, and CastStrategyC.

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

virtual int4 CastStrategy::localExtensionType ( const Varnode * vn ) const

pure virtual

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

Parameters

vn	is the given Varnode

Returns: an IntPromotionCode (excluding NO_PROMOTION)

Implemented in CastStrategyC.

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

void 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 TypeFactory::getSizeOfInt(), promoteSize, and tlst.

Referenced by CastStrategy().

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

Member Function Documentation