ghidra::PcodeCacher Class Reference

Class for caching a chunk of p-code, prior to emitting. More...

#include <sleigh.hh>

Public Member Functions
	PcodeCacher (void)
	Constructor.
	~PcodeCacher (void)
	Destructor.
VarnodeData *	allocateVarnodes (uint4 size)
	Allocate data objects for a new set of Varnodes. More...
PcodeData *	allocateInstruction (void)
	Allocate a data object for a new p-code operation. More...
void	addLabelRef (VarnodeData *ptr)
	Denote a Varnode holding a relative branch offset. More...
void	addLabel (uint4 id)
	Attach a label to the next p-code instruction. More...
void	clear (void)
	Reset the cache so that all objects are unallocated.
void	resolveRelatives (void)
	Rewrite branch target Varnodes as relative offsets. More...
void	emit (const Address &addr, PcodeEmit *emt) const
	Pass the cached p-code data to the emitter. More...

Private Member Functions
VarnodeData *	expandPool (uint4 size)
	Expand the memory pool. More...

Private Attributes
VarnodeData *	poolstart
	Start of the pool of VarnodeData objects.
VarnodeData *	curpool
	First unused VarnodeData.
VarnodeData *	endpool
	End of the pool of VarnodeData objects.
vector< PcodeData >	issued
	P-code ops issued for the current instruction.
list< RelativeRecord >	label_refs
	References to labels.
vector< uintb >	labels
	Locations of labels.

Detailed Description

Class for caching a chunk of p-code, prior to emitting.

The engine accumulates PcodeData and VarnodeData objects for a single instruction. Once the full instruction is constructed, the objects are passed to the emitter (PcodeEmit) via the emit() method. The class acts as a pool of memory for PcodeData and VarnodeData objects that can be reused repeatedly to emit multiple instructions.

Member Function Documentation

addLabel()

void ghidra::PcodeCacher::addLabel

(

uint4

id

)

Attach a label to the next p-code instruction.

The label has an id that is referred to by Varnodes holding intra-instruction branch targets, prior to converting them to a relative branch offset. The label is associated with the absolute index of the next PcodeData object to be issued, facilitating this conversion.

Parameters

id	is the given id of the label

References issued, and labels.

Referenced by ghidra::SleighBuilder::SleighBuilder().

addLabelRef()

void ghidra::PcodeCacher::addLabelRef

(

VarnodeData *

ptr

)

Denote a Varnode holding a relative branch offset.

Store off a reference to the Varnode and the absolute index of the next instruction. The Varnode must be an operand of the current instruction.

Parameters

ptr	is the Varnode reference

References issued, and label_refs.

allocateInstruction()

PcodeData* ghidra::PcodeCacher::allocateInstruction ( void  )

inline

Allocate a data object for a new p-code operation.

Returns

the new PcodeData object

References ghidra::PcodeData::invar, and ghidra::PcodeData::outvar.

allocateVarnodes()

VarnodeData* ghidra::PcodeCacher::allocateVarnodes ( uint4  size )

inline

Allocate data objects for a new set of Varnodes.

Parameters

size	is the number of objects to allocate

Returns

a pointer to the array of available VarnodeData objects

emit()

void ghidra::PcodeCacher::emit	(	const Address &	addr,
		PcodeEmit *	emt
	)		const

Pass the cached p-code data to the emitter.

Each p-code operation is presented to the emitter via its dump() method.

Parameters

addr	is the Address associated with the p-code operation
emt	is the emitter

References ghidra::PcodeEmit::dump(), and issued.

Referenced by ghidra::Sleigh::oneInstruction().

expandPool()

VarnodeData * ghidra::PcodeCacher::expandPool ( uint4  size )

private

Expand the memory pool.

Expand the VarnodeData pool so that size more elements fit, and return a pointer to first available element.

Parameters

size	is the number of elements to expand the pool by

Returns

the first available VarnodeData

References curpool, endpool, issued, label_refs, and poolstart.

resolveRelatives()

void ghidra::PcodeCacher::resolveRelatives

(

void

)

Rewrite branch target Varnodes as relative offsets.

Assuming all the PcodeData has been generated for an instruction, go resolve any relative offsets and back patch their value(s) into the PcodeData

References ghidra::calc_mask(), label_refs, labels, ghidra::VarnodeData::offset, and ghidra::VarnodeData::size.

Referenced by ghidra::Sleigh::oneInstruction().

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

• sleigh.hh
• sleigh.cc