Base class template for dataflow analyses built on a single lattice type. More...

#include "clang/Analysis/FlowSensitive/DataflowAnalysis.h"

Inheritance diagram for clang::dataflow::DataflowAnalysis< Derived, LatticeT >:

[legend]

Public Types
using	Lattice = LatticeT
	Bounded join-semilattice that is used in the analysis.

Public Member Functions
	DataflowAnalysis (ASTContext &Context)

	DataflowAnalysis (ASTContext &Context, DataflowAnalysisOptions Options)

ASTContext &	getASTContext () final
	Returns the `ASTContext` that is used by the analysis.

TypeErasedLattice	typeErasedInitialElement () final
	Returns a type-erased lattice element that models the initial state of a basic block.

TypeErasedLattice	joinTypeErased (const TypeErasedLattice &E1, const TypeErasedLattice &E2) final
	Joins two type-erased lattice elements by computing their least upper bound.

LatticeJoinEffect	widenTypeErased (TypeErasedLattice &Current, const TypeErasedLattice &Previous) final
	Chooses a lattice element that approximates the current element at a program point, given the previous element at that point.

bool	isEqualTypeErased (const TypeErasedLattice &E1, const TypeErasedLattice &E2) final
	Returns true if and only if the two given type-erased lattice elements are equal.

void	transferTypeErased (const CFGElement &Element, TypeErasedLattice &E, Environment &Env) final
	Applies the analysis transfer function for a given control flow graph element and type-erased lattice element.

void	transferBranchTypeErased (bool Branch, const Stmt *Stmt, TypeErasedLattice &E, Environment &Env) final
	Applies the analysis transfer function for a given edge from a CFG block of a conditional statement.

Public Member Functions inherited from clang::dataflow::TypeErasedDataflowAnalysis
	TypeErasedDataflowAnalysis ()

	TypeErasedDataflowAnalysis (DataflowAnalysisOptions Options)

virtual	~TypeErasedDataflowAnalysis ()

virtual ASTContext &	getASTContext ()=0
	Returns the `ASTContext` that is used by the analysis.

virtual TypeErasedLattice	typeErasedInitialElement ()=0
	Returns a type-erased lattice element that models the initial state of a basic block.

virtual TypeErasedLattice	joinTypeErased (const TypeErasedLattice &, const TypeErasedLattice &)=0
	Joins two type-erased lattice elements by computing their least upper bound.

virtual LatticeJoinEffect	widenTypeErased (TypeErasedLattice &Current, const TypeErasedLattice &Previous)=0
	Chooses a lattice element that approximates the current element at a program point, given the previous element at that point.

virtual bool	isEqualTypeErased (const TypeErasedLattice &, const TypeErasedLattice &)=0
	Returns true if and only if the two given type-erased lattice elements are equal.

virtual void	transferTypeErased (const CFGElement &, TypeErasedLattice &, Environment &)=0
	Applies the analysis transfer function for a given control flow graph element and type-erased lattice element.

virtual void	transferBranchTypeErased (bool Branch, const Stmt *, TypeErasedLattice &, Environment &)=0
	Applies the analysis transfer function for a given edge from a CFG block of a conditional statement.

const std::optional< DataflowAnalysisContext::Options > &	builtinOptions () const
	If the built-in model is enabled, returns the options to be passed to them.

Public Member Functions inherited from clang::dataflow::Environment::ValueModel
virtual	~ValueModel ()=default

virtual ComparisonResult	compare (QualType Type, const Value &Val1, const Environment &Env1, const Value &Val2, const Environment &Env2)
	Returns: `Same`: `Val1` is equivalent to `Val2`, according to the model.

virtual void	join (QualType Type, const Value &Val1, const Environment &Env1, const Value &Val2, const Environment &Env2, Value &JoinedVal, Environment &JoinedEnv)
	Modifies `JoinedVal` to approximate both `Val1` and `Val2`.

virtual std::optional< WidenResult >	widen (QualType Type, Value &Prev, const Environment &PrevEnv, Value &Current, Environment &CurrentEnv)
	This function may widen the current value – replace it with an approximation that can reach a fixed point more quickly than iterated application of the transfer function alone.

Detailed Description

template<typename Derived, typename LatticeT>
class clang::dataflow::DataflowAnalysis< Derived, LatticeT >

Base class template for dataflow analyses built on a single lattice type.

Requirements:

Derived must be derived from a specialization of this class template and must provide the following public members:

LatticeT initialElement() - returns a lattice element that models the initial state of a basic block;
void transfer(const CFGElement &, LatticeT &, Environment &) - applies the analysis transfer function for a given CFG element and lattice element.

Derived can optionally provide the following members:

void transferBranch(bool Branch, const Stmt *Stmt, TypeErasedLattice &E, Environment &Env) - applies the analysis transfer function for a given edge from a CFG block of a conditional statement.

Derived can optionally override the virtual functions in the Environment::ValueModel interface (which is an indirect base class of this class).

LatticeT is a bounded join-semilattice that is used by Derived and must provide the following public members:

LatticeJoinEffect join(const LatticeT &) - joins the object and the argument by computing their least upper bound, modifies the object if necessary, and returns an effect indicating whether any changes were made to it; FIXME: make it static LatticeT join(const LatticeT&, const LatticeT&)
bool operator==(const LatticeT &) const - returns true if and only if the object is equal to the argument.

LatticeT can optionally provide the following members:

LatticeJoinEffect widen(const LatticeT &Previous) - replaces the lattice element with an approximation that can reach a fixed point more quickly than iterated application of the transfer function alone. The previous value is provided to inform the choice of widened value. The function must also serve as a comparison operation, by indicating whether the widened value is equivalent to the previous value with the returned LatticeJoinEffect.

Definition at line 80 of file DataflowAnalysis.h.

Member Typedef Documentation

◆ Lattice

template<typename Derived , typename LatticeT >

using clang::dataflow::DataflowAnalysis< Derived, LatticeT >::Lattice = LatticeT

Bounded join-semilattice that is used in the analysis.

Definition at line 83 of file DataflowAnalysis.h.

Constructor & Destructor Documentation

◆ DataflowAnalysis() [1/2]

template<typename Derived , typename LatticeT >

clang::dataflow::DataflowAnalysis< Derived, LatticeT >::DataflowAnalysis ( ASTContext & Context )

inlineexplicit

Definition at line 85 of file DataflowAnalysis.h.

◆ DataflowAnalysis() [2/2]

template<typename Derived , typename LatticeT >

clang::dataflow::DataflowAnalysis< Derived, LatticeT >::DataflowAnalysis	(	ASTContext &	Context,
		DataflowAnalysisOptions	Options
	)

inlineexplicit

Definition at line 87 of file DataflowAnalysis.h.

Member Function Documentation

◆ getASTContext()

template<typename Derived , typename LatticeT >

ASTContext & clang::dataflow::DataflowAnalysis< Derived, LatticeT >::getASTContext ( )

inlinefinalvirtual

Returns the ASTContext that is used by the analysis.

Implements clang::dataflow::TypeErasedDataflowAnalysis.

Definition at line 91 of file DataflowAnalysis.h.

◆ isEqualTypeErased()

template<typename Derived , typename LatticeT >

bool clang::dataflow::DataflowAnalysis< Derived, LatticeT >::isEqualTypeErased	(	const TypeErasedLattice &	,
		const TypeErasedLattice &
	)

inlinefinalvirtual

Returns true if and only if the two given type-erased lattice elements are equal.

Implements clang::dataflow::TypeErasedDataflowAnalysis.

Definition at line 113 of file DataflowAnalysis.h.

◆ joinTypeErased()

template<typename Derived , typename LatticeT >

TypeErasedLattice clang::dataflow::DataflowAnalysis< Derived, LatticeT >::joinTypeErased	(	const TypeErasedLattice &	,
		const TypeErasedLattice &
	)

inlinefinalvirtual

Joins two type-erased lattice elements by computing their least upper bound.

Places the join result in the left element and returns an effect indicating whether any changes were made to it.

Implements clang::dataflow::TypeErasedDataflowAnalysis.

Definition at line 97 of file DataflowAnalysis.h.

◆ transferBranchTypeErased()

template<typename Derived , typename LatticeT >

void clang::dataflow::DataflowAnalysis< Derived, LatticeT >::transferBranchTypeErased	(	bool	Branch,
		const Stmt *	,
		TypeErasedLattice &	,
		Environment &
	)

inlinefinalvirtual

Applies the analysis transfer function for a given edge from a CFG block of a conditional statement.

Parameters

Stmt	The condition which is responsible for the split in the CFG.
Branch	True if the edge goes to the basic block where the condition is true.

Implements clang::dataflow::TypeErasedDataflowAnalysis.

Definition at line 126 of file DataflowAnalysis.h.

References Env.

◆ transferTypeErased()

template<typename Derived , typename LatticeT >

void clang::dataflow::DataflowAnalysis< Derived, LatticeT >::transferTypeErased	(	const CFGElement &	,
		TypeErasedLattice &	,
		Environment &
	)

inlinefinalvirtual

Applies the analysis transfer function for a given control flow graph element and type-erased lattice element.

Implements clang::dataflow::TypeErasedDataflowAnalysis.

Definition at line 120 of file DataflowAnalysis.h.

References Env, and clang::dataflow::transfer().

◆ typeErasedInitialElement()

template<typename Derived , typename LatticeT >

TypeErasedLattice clang::dataflow::DataflowAnalysis< Derived, LatticeT >::typeErasedInitialElement ( )

inlinefinalvirtual

Returns a type-erased lattice element that models the initial state of a basic block.

Implements clang::dataflow::TypeErasedDataflowAnalysis.

Definition at line 93 of file DataflowAnalysis.h.

◆ widenTypeErased()

template<typename Derived , typename LatticeT >

LatticeJoinEffect clang::dataflow::DataflowAnalysis< Derived, LatticeT >::widenTypeErased	(	TypeErasedLattice &	Current,
		const TypeErasedLattice &	Previous
	)

inlinefinalvirtual

Chooses a lattice element that approximates the current element at a program point, given the previous element at that point.

Places the widened result in the current element (Current). Widening is optional – it is only needed to either accelerate convergence (for lattices with non-trivial height) or guarantee convergence (for lattices with infinite height).

Returns an indication of whether any changes were made to Current in order to widen. This saves a separate call to isEqualTypeErased after the widening.

Implements clang::dataflow::TypeErasedDataflowAnalysis.

Definition at line 106 of file DataflowAnalysis.h.

References clang::C, P, and Previous.

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

include/clang/Analysis/FlowSensitive/DataflowAnalysis.h

Public Types

Public Member Functions

Detailed Description

Member Typedef Documentation

◆ Lattice

Constructor & Destructor Documentation

◆ DataflowAnalysis() [1/2]

◆ DataflowAnalysis() [2/2]

Member Function Documentation

◆ getASTContext()

◆ isEqualTypeErased()

◆ joinTypeErased()

◆ transferBranchTypeErased()

◆ transferTypeErased()

◆ typeErasedInitialElement()

◆ widenTypeErased()