RuleThreeWayCompare Class Reference

Simplify expressions involving three-way comparisons. More...

Inheritance diagram for RuleThreeWayCompare:

Collaboration diagram for RuleThreeWayCompare:

Public Member Functions
virtual Rule *	clone (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 Rule
	Rule (const string &g, uint4 fl, const string &nm)
	Construct given group, properties name. More...
bool	checkActionBreak (void)
	Check if an action breakpoint is turned on. More...
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...

Static Public Member Functions
static PcodeOp *	detectThreeWay (PcodeOp *op, bool &isPartial)
	Detect a three-way calculation. More...
static int4	testCompareEquivalence (PcodeOp *lessop, PcodeOp *lessequalop)
	Make sure comparisons match properly for a three-way. More...

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

Detailed Description

Simplify expressions involving three-way comparisons.

A three-way comparison is the expression

• X = zext( V < W ) + ZEXT( V <= W ) - 1 in some permutation

This gives the result (-1, 0, or 1) depending on whether V is less-than, equal, or greater-than W. This Rule looks for secondary comparisons of the three-way, such as

• X < 1 which simplifies to
• V <= W

Member Function Documentation

applyOp()

int4 RuleThreeWayCompare::applyOp ( PcodeOp *  op, Funcdata &  data  )

virtual

Attempt to apply this Rule.

This method contains the main logic for applying the Rule. It must use a given PcodeOp as the point at which the Rule applies. If it does apply, changes are made directly to the function and 1 (non-zero) is returned, otherwise 0 is returned.

Parameters

op	is the given PcodeOp where the Rule may apply
data	is the function to which to apply

Reimplemented from Rule.

clone()

virtual Rule* RuleThreeWayCompare::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

grouplist

is the list of groups being cloned

Returns

the cloned Rule or NULL

Implements Rule.

detectThreeWay()

PcodeOp * RuleThreeWayCompare::detectThreeWay ( PcodeOp *  op, bool &  isPartial  )

static

Detect a three-way calculation.

A three-way expression looks like:

• zext( V < W ) + zext( V <= W ) - 1 in some permutation

The comparisons can signed, unsigned, or floating-point.

Parameters

op	is the putative root INT_ADD of the calculation
isPartial	is set to true if a partial form is detected

Returns

the less-than op or NULL if no three-way was detected

getOpList()

void RuleThreeWayCompare::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

oplist

is the array to populate

Reimplemented from Rule.

testCompareEquivalence()

int4 RuleThreeWayCompare::testCompareEquivalence ( PcodeOp *  lessop, PcodeOp *  lessequalop  )

static

Make sure comparisons match properly for a three-way.

Given zext(V < W) + zext(X <= Y), make sure comparisons match, i.e V matches X and W matches Y. Take into account that the LESSEQUAL may have been converted to a LESS. Return:

• 0 if configuration is correct
• 1 if correct but roles of lessop and lessequalop must be swapped
• -1 if not the correct configuration

  Parameters

  lessop	is the putative LESS PcodeOp
  lessequalop	is the putative LESSEQUAL PcodeOp

  Returns

  0, 1, or -1

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

• ruleaction.hh
• ruleaction.cc