retdec
Public Member Functions | Static Public Member Functions | Private Member Functions | List of all members
retdec::llvmir2hll::ZeroSubOptimizer Class Referencefinal

This optimizer changes expressions where one of the operands is a zero. Examples are mentioned below. More...

#include <zero_sub_optimizer.h>

Inheritance diagram for retdec::llvmir2hll::ZeroSubOptimizer:
Inheritance graph
[legend]
Collaboration diagram for retdec::llvmir2hll::ZeroSubOptimizer:
Collaboration graph
[legend]

Public Member Functions

 ZeroSubOptimizer (ShPtr< ArithmExprEvaluator > arithmExprEvaluator)
 Constructs the ZeroSubOptimizer. More...
 
virtual std::string getId () const override
 Returns the ID of the optimizer. More...
 
- Public Member Functions inherited from retdec::llvmir2hll::SubOptimizer
virtual bool tryOptimize (ShPtr< Expression > expr)
 Run optimization and try to optimize. More...
 
- Public Member Functions inherited from retdec::llvmir2hll::OrderedAllVisitor
virtual void visit (ShPtr< GlobalVarDef > varDef) override
 
virtual void visit (ShPtr< Function > func) override
 
virtual void visit (ShPtr< AssignStmt > stmt) override
 
virtual void visit (ShPtr< BreakStmt > stmt) override
 
virtual void visit (ShPtr< CallStmt > stmt) override
 
virtual void visit (ShPtr< ContinueStmt > stmt) override
 
virtual void visit (ShPtr< EmptyStmt > stmt) override
 
virtual void visit (ShPtr< ForLoopStmt > stmt) override
 
virtual void visit (ShPtr< UForLoopStmt > stmt) override
 
virtual void visit (ShPtr< GotoStmt > stmt) override
 
virtual void visit (ShPtr< IfStmt > stmt) override
 
virtual void visit (ShPtr< ReturnStmt > stmt) override
 
virtual void visit (ShPtr< SwitchStmt > stmt) override
 
virtual void visit (ShPtr< UnreachableStmt > stmt) override
 
virtual void visit (ShPtr< VarDefStmt > stmt) override
 
virtual void visit (ShPtr< WhileLoopStmt > stmt) override
 
virtual void visit (ShPtr< AddressOpExpr > expr) override
 
virtual void visit (ShPtr< AndOpExpr > expr) override
 
virtual void visit (ShPtr< ArrayIndexOpExpr > expr) override
 
virtual void visit (ShPtr< AssignOpExpr > expr) override
 
virtual void visit (ShPtr< BitShlOpExpr > expr) override
 
virtual void visit (ShPtr< BitShrOpExpr > expr) override
 
virtual void visit (ShPtr< CallExpr > expr) override
 
virtual void visit (ShPtr< CommaOpExpr > expr) override
 
virtual void visit (ShPtr< DerefOpExpr > expr) override
 
virtual void visit (ShPtr< EqOpExpr > expr) override
 
virtual void visit (ShPtr< GtEqOpExpr > expr) override
 
virtual void visit (ShPtr< GtOpExpr > expr) override
 
virtual void visit (ShPtr< LtEqOpExpr > expr) override
 
virtual void visit (ShPtr< LtOpExpr > expr) override
 
virtual void visit (ShPtr< NegOpExpr > expr) override
 
virtual void visit (ShPtr< NeqOpExpr > expr) override
 
virtual void visit (ShPtr< NotOpExpr > expr) override
 
virtual void visit (ShPtr< OrOpExpr > expr) override
 
virtual void visit (ShPtr< StructIndexOpExpr > expr) override
 
virtual void visit (ShPtr< TernaryOpExpr > expr) override
 
virtual void visit (ShPtr< Variable > var) override
 
virtual void visit (ShPtr< BitCastExpr > expr) override
 
virtual void visit (ShPtr< ExtCastExpr > expr) override
 
virtual void visit (ShPtr< FPToIntCastExpr > expr) override
 
virtual void visit (ShPtr< IntToFPCastExpr > expr) override
 
virtual void visit (ShPtr< IntToPtrCastExpr > expr) override
 
virtual void visit (ShPtr< PtrToIntCastExpr > expr) override
 
virtual void visit (ShPtr< TruncCastExpr > expr) override
 
virtual void visit (ShPtr< ConstArray > constant) override
 
virtual void visit (ShPtr< ConstBool > constant) override
 
virtual void visit (ShPtr< ConstFloat > constant) override
 
virtual void visit (ShPtr< ConstInt > constant) override
 
virtual void visit (ShPtr< ConstNullPointer > constant) override
 
virtual void visit (ShPtr< ConstString > constant) override
 
virtual void visit (ShPtr< ConstStruct > constant) override
 
virtual void visit (ShPtr< ConstSymbol > constant) override
 
virtual void visit (ShPtr< ArrayType > type) override
 
virtual void visit (ShPtr< FloatType > type) override
 
virtual void visit (ShPtr< IntType > type) override
 
virtual void visit (ShPtr< PointerType > type) override
 
virtual void visit (ShPtr< StringType > type) override
 
virtual void visit (ShPtr< StructType > type) override
 
virtual void visit (ShPtr< FunctionType > type) override
 
virtual void visit (ShPtr< VoidType > type) override
 
virtual void visit (ShPtr< UnknownType > type) override
 
- Public Member Functions inherited from retdec::llvmir2hll::Visitor
virtual ~Visitor ()=default
 

Static Public Member Functions

static ShPtr< SubOptimizercreate (ShPtr< ArithmExprEvaluator > arithmExprEvaluator)
 Creates a new ZeroSubOptimizer. More...
 

Private Member Functions

bool isConstFloatZero (ShPtr< Expression > expr) const
 Check if expression is a ConstFloat zero. More...
 
bool isConstIntZero (ShPtr< Expression > expr) const
 Check if expression is a ConstInt zero. More...
 
bool isOpZero (ShPtr< Expression > expr) const
 Check if expression is a ConstInt or ConstFloat zero. More...
 
Visitor Interface
virtual void visit (ShPtr< AddOpExpr > expr) override
 
virtual void visit (ShPtr< SubOpExpr > expr) override
 
virtual void visit (ShPtr< MulOpExpr > expr) override
 
virtual void visit (ShPtr< DivOpExpr > expr) override
 
virtual void visit (ShPtr< ModOpExpr > expr) override
 
virtual void visit (ShPtr< BitAndOpExpr > expr) override
 
virtual void visit (ShPtr< BitOrOpExpr > expr) override
 
virtual void visit (ShPtr< BitXorOpExpr > expr) override
 

Additional Inherited Members

- Protected Member Functions inherited from retdec::llvmir2hll::SubOptimizer
 SubOptimizer (ShPtr< ArithmExprEvaluator > arithmExprEvaluator)
 Constructs the SubOptimizer. More...
 
bool isConstFloatOrConstInt (ShPtr< Expression > expr) const
 Check if expression is a ConstInt or ConstFloat. More...
 
void optimizeExpr (ShPtr< Expression > oldExpr, ShPtr< Expression > newExpr)
 Optimize expression from oldExpr to newExpr. More...
 
bool tryOptimizeAndReturnIfCodeChanged (ShPtr< Expression > expr)
 Start traversal in abstract syntax tree. More...
 
- Protected Member Functions inherited from retdec::llvmir2hll::OrderedAllVisitor
 OrderedAllVisitor (bool visitSuccessors=true, bool visitNestedStmts=true)
 Constructs a new visitor. More...
 
virtual void visitStmt (ShPtr< Statement > stmt, bool visitSuccessors=true, bool visitNestedStmts=true)
 Visits the given statement, and possibly its successors or nested statements. More...
 
void restart (bool visitSuccessors=true, bool visitNestedStmts=true)
 "Restarts" the visitor so it is in the state like it was when it was created. More...
 
bool makeAccessedAndCheckIfAccessed (ShPtr< Type > type)
 Makes the given type accessed. More...
 
- Protected Member Functions inherited from retdec::llvmir2hll::Visitor
 Visitor ()=default
 
- Protected Attributes inherited from retdec::llvmir2hll::SubOptimizer
ShPtr< ArithmExprEvaluatorarithmExprEvaluator
 The used evaluator of arithmetical expressions. More...
 
- Protected Attributes inherited from retdec::llvmir2hll::OrderedAllVisitor
ShPtr< StatementlastStmt
 Statement that has been accessed as the last one. More...
 
StmtUSet accessedStmts
 A set of all accessed statements. More...
 
TypeUSet accessedTypes
 A set of all accessed types. More...
 
bool visitSuccessors
 Should statements' successor be accessed? More...
 
bool visitNestedStmts
 Should nested statements be accessed? More...
 

Detailed Description

This optimizer changes expressions where one of the operands is a zero. Examples are mentioned below.

Optimizations are now only on these operators: +, -, *, /, %, &, |, ^.

List of performed simplifications (by examples):

Operator +
0(ConstInt/ConstFloat) + anything (vica versa).
return 0 + a;
can be optimized to
return a;
Operator &
0(ConstInt) & anything (vica versa).
return 0 & a;
can be optimized to
return 0;
Operator |
0(ConstInt) | anything (vica versa).
return 0 | a;
can be optimized to
return a;
Operator ^
0(ConstInt) ^ anything (vica versa).
return 0 ^ a;
can be optimized to
return a;
Operator -
0(ConstInt/ConstFloat) - (ConstInt/ConstFloat).
return 0 - 2;
can be optimized to
return -2;
0(ConstInt/ConstFloat) - (NegOpExpr).
return 0 - a(NegOpExpr);
can be optimized to
return a;
0(ConstInt/ConstFloat) - anything(Not NegOpExpr).
return 0 - a(Not NegOpExpr);
can be optimized to
return a(NegOpExpr);
Anything - 0(ConstInt/ConstFloat).
return a - 0;
can be optimized to
return a;
Operator *
0(ConstInt/ConstFloat) * anything (vica versa).
return 0 * a;
can be optimized to
return 0;
Operator /
0(ConstInt/ConstFloat) / anything.
return 0 / a;
can be optimized to
return 0;
Operator %
0(ConstInt/ConstFloat) % anything.
return 0 % a;
can be optimized to
return 0;

Instances of this class have reference object semantics.

This is a concrete sub-optimizer which should not be subclassed.

Constructor & Destructor Documentation

◆ ZeroSubOptimizer()

retdec::llvmir2hll::ZeroSubOptimizer::ZeroSubOptimizer ( ShPtr< ArithmExprEvaluator arithmExprEvaluator)

Constructs the ZeroSubOptimizer.

Parameters
[in]arithmExprEvaluatorThe used evaluator of arithmetical expressions.

Member Function Documentation

◆ create()

ShPtr< SubOptimizer > retdec::llvmir2hll::ZeroSubOptimizer::create ( ShPtr< ArithmExprEvaluator arithmExprEvaluator)
static

Creates a new ZeroSubOptimizer.

Parameters
[in]arithmExprEvaluatorThe used evaluator of arithmetical expressions.

◆ getId()

std::string retdec::llvmir2hll::ZeroSubOptimizer::getId ( ) const
overridevirtual

Returns the ID of the optimizer.

Implements retdec::llvmir2hll::SubOptimizer.

◆ isConstFloatZero()

bool retdec::llvmir2hll::ZeroSubOptimizer::isConstFloatZero ( ShPtr< Expression expr) const
private

Check if expression is a ConstFloat zero.

Parameters
[in]exprExpression to check.
Returns
true if expr is a ConstFloat zero, otherwise false.

◆ isConstIntZero()

bool retdec::llvmir2hll::ZeroSubOptimizer::isConstIntZero ( ShPtr< Expression expr) const
private

Check if expression is a ConstInt zero.

Parameters
[in]exprExpression to check.
Returns
true if expr is a ConstInt zero, otherwise false.

◆ isOpZero()

bool retdec::llvmir2hll::ZeroSubOptimizer::isOpZero ( ShPtr< Expression expr) const
private

Check if expression is a ConstInt or ConstFloat zero.

Parameters
[in]exprExpression to check.
Returns
true if expr is a ConstInt or ConstFloat zero, otherwise false.

◆ visit() [1/8]

void retdec::llvmir2hll::ZeroSubOptimizer::visit ( ShPtr< AddOpExpr expr)
overrideprivatevirtual

◆ visit() [2/8]

void retdec::llvmir2hll::ZeroSubOptimizer::visit ( ShPtr< BitAndOpExpr expr)
overrideprivatevirtual

◆ visit() [3/8]

void retdec::llvmir2hll::ZeroSubOptimizer::visit ( ShPtr< BitOrOpExpr expr)
overrideprivatevirtual

◆ visit() [4/8]

void retdec::llvmir2hll::ZeroSubOptimizer::visit ( ShPtr< BitXorOpExpr expr)
overrideprivatevirtual

◆ visit() [5/8]

void retdec::llvmir2hll::ZeroSubOptimizer::visit ( ShPtr< DivOpExpr expr)
overrideprivatevirtual

◆ visit() [6/8]

void retdec::llvmir2hll::ZeroSubOptimizer::visit ( ShPtr< ModOpExpr expr)
overrideprivatevirtual

◆ visit() [7/8]

void retdec::llvmir2hll::ZeroSubOptimizer::visit ( ShPtr< MulOpExpr expr)
overrideprivatevirtual

◆ visit() [8/8]

void retdec::llvmir2hll::ZeroSubOptimizer::visit ( ShPtr< SubOpExpr expr)
overrideprivatevirtual

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