decompiler  1.0.0
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ghidra::RuleOrPredicate Class Reference

Simplify predication constructions involving the INT_OR operator. More...

#include <condexe.hh>

Inheritance diagram for ghidra::RuleOrPredicate:
ghidra::Rule

Classes

struct  MultiPredicate
 A helper class to mark up predicated INT_OR expressions. More...
 

Public Member Functions

 RuleOrPredicate (const string &g)
 Constructor.
 
virtual Ruleclone (const ActionGroupList &grouplist) const
 Clone the Rule. More...
 
virtual void getOpList (vector< uint4 > &oplist) const
 List of op codes this rule operates on. More...
 
virtual int4 applyOp (PcodeOp *op, Funcdata &data)
 Attempt to apply this Rule. More...
 
- Public Member Functions inherited from ghidra::Rule
 Rule (const string &g, uint4 fl, const string &nm)
 Construct given group, properties name. More...
 
virtual ~Rule (void)
 Destructor.
 
const string & getName (void) const
 Return the name of this Rule.
 
const string & getGroup (void) const
 Return the group this Rule belongs to.
 
uint4 getNumTests (void)
 Get number of attempted applications.
 
uint4 getNumApply (void)
 Get number of successful applications.
 
void setBreak (uint4 tp)
 Set a breakpoint on this Rule.
 
void clearBreak (uint4 tp)
 Clear a breakpoint on this Rule.
 
void clearBreakPoints (void)
 Clear all breakpoints on this Rule.
 
void turnOnWarnings (void)
 Enable warnings for this Rule.
 
void turnOffWarnings (void)
 Disable warnings for this Rule.
 
bool isDisabled (void) const
 Return true if this Rule is disabled.
 
void setDisable (void)
 Disable this Rule (within its pool)
 
void clearDisable (void)
 Enable this Rule (within its pool)
 
bool checkActionBreak (void)
 Check if an action breakpoint is turned on. More...
 
uint4 getBreakPoint (void) const
 Return breakpoint toggles.
 
virtual void reset (Funcdata &data)
 Reset this Rule. More...
 
virtual void resetStats (void)
 Reset Rule statistics. More...
 
virtual void printStatistics (ostream &s) const
 Print statistics for this Rule. More...
 

Private Member Functions

int4 checkSingle (Varnode *vn, MultiPredicate &branch, PcodeOp *op, Funcdata &data)
 Check for the alternate form, tmp1 = (val2 == 0) ? val1 : 0;. More...
 

Additional Inherited Members

- Public Types inherited from ghidra::Rule
enum  typeflags { type_disable = 1, rule_debug = 2, warnings_on = 4, warnings_given = 8 }
 Properties associated with a Rule. More...
 

Detailed Description

Simplify predication constructions involving the INT_OR operator.

In this form of predication, two variables are set based on a condition and then ORed together. Both variables may be set to zero, or to some other value, based on the condition and the zero values are such that at least one of the variables is zero.

tmp1 = cond ? val1 : 0;
tmp2 = cond ? 0 : val2;
result = tmp1 | tmp2;

The RuleOrPredicate simplifies this to

if (cond) result = val1; else result = val2;

or to be precise

newtmp = val1 ? val2; // Using a new MULTIEQUAL
result = newtmp;

In an alternate form we have

tmp1 = (val2 == 0) ? val1 : 0
result = tmp1 | val2;

again, one of val1 or val2 must be zero, so this gets replaced with

tmp1 = val1 ? val2
result = tmp1

Member Function Documentation

◆ applyOp()

int4 ghidra::RuleOrPredicate::applyOp ( PcodeOp op,
Funcdata data 
)
virtual

◆ checkSingle()

int4 ghidra::RuleOrPredicate::checkSingle ( Varnode vn,
MultiPredicate branch,
PcodeOp op,
Funcdata data 
)
private

Check for the alternate form, tmp1 = (val2 == 0) ? val1 : 0;.

We know we have the basic form

tmp1 = cond ? val1 : 0;
result = tmp1 | other;

So we just need to check that other plays the role of val2. If we match the alternate form, perform the simplification

Parameters
vnis the candidate other Varnode
branchholds the basic form
opis the INT_OR p-code op
datais the function being analyzed
Returns
1 if the form was matched and simplified, 0 otherwise

References ghidra::CPUI_COPY, ghidra::RuleOrPredicate::MultiPredicate::discoverCbranch(), ghidra::RuleOrPredicate::MultiPredicate::discoverConditionalZero(), ghidra::RuleOrPredicate::MultiPredicate::discoverPathIsTrue(), ghidra::PcodeOp::getOut(), ghidra::Varnode::isFree(), ghidra::Varnode::loneDescend(), ghidra::RuleOrPredicate::MultiPredicate::op, ghidra::Funcdata::opRemoveInput(), ghidra::Funcdata::opSetInput(), ghidra::Funcdata::opSetOpcode(), ghidra::RuleOrPredicate::MultiPredicate::zeroPathIsTrue, and ghidra::RuleOrPredicate::MultiPredicate::zeroSlot.

◆ clone()

virtual Rule* ghidra::RuleOrPredicate::clone ( const ActionGroupList grouplist) const
inlinevirtual

Clone the Rule.

If this Rule is a member of one of the groups in the grouplist, this returns a clone of the Rule, otherwise NULL is returned.

Parameters
grouplistis the list of groups being cloned
Returns
the cloned Rule or NULL

Implements ghidra::Rule.

References ghidra::ActionGroupList::contains().

◆ getOpList()

void ghidra::RuleOrPredicate::getOpList ( vector< uint4 > &  oplist) const
virtual

List of op codes this rule operates on.

Populate the given array with all possible OpCodes this Rule might apply to. By default, this method returns all possible OpCodes

Parameters
oplistis the array to populate

Reimplemented from ghidra::Rule.

References ghidra::CPUI_INT_OR, and ghidra::CPUI_INT_XOR.


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