clang::dataflow::Environment::ValueModel Class Reference

Supplements Environment with non-standard comparison and join operations. More...

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

Inheritance diagram for clang::dataflow::Environment::ValueModel:

Public Member Functions
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

Supplements Environment with non-standard comparison and join operations.

Definition at line 66 of file DataflowEnvironment.h.

Constructor & Destructor Documentation

~ValueModel()

virtual clang::dataflow::Environment::ValueModel::~ValueModel ( )

virtualdefault

Member Function Documentation

compare()

virtual ComparisonResult clang::dataflow::Environment::ValueModel::compare ( QualType  Type, const Value &  Val1, const Environment &  Env1, const Value &  Val2, const Environment &  Env2  )

inlinevirtual

Returns: Same: Val1 is equivalent to Val2, according to the model.

Different: Val1 is distinct from Val2, according to the model. Unknown: The model can't determine a relationship between Val1 and Val2.

Requirements:

Val1 and Val2 must be distinct.

Val1 and Val2 must model values of type Type.

Val1 and Val2 must be assigned to the same storage location in Env1 and Env2 respectively.

Definition at line 84 of file DataflowEnvironment.h.

References clang::dataflow::Unknown.

Referenced by clang::dataflow::compareDistinctValues(), and widen().

join()

virtual void clang::dataflow::Environment::ValueModel::join ( QualType  Type, const Value &  Val1, const Environment &  Env1, const Value &  Val2, const Environment &  Env2, Value &  JoinedVal, Environment &  JoinedEnv  )

inlinevirtual

Modifies JoinedVal to approximate both Val1 and Val2.

This should obey the properties of a lattice join.

Env1 and Env2 can be used to query child values and path condition implications of Val1 and Val2 respectively.

Requirements:

Val1 and Val2 must be distinct.

Val1, Val2, and JoinedVal must model values of type Type.

Val1 and Val2 must be assigned to the same storage location in Env1 and Env2 respectively.

Definition at line 106 of file DataflowEnvironment.h.

Referenced by clang::dataflow::joinDistinctValues().

widen()

virtual std::optional< WidenResult > clang::dataflow::Environment::ValueModel::widen ( QualType  Type, Value &  Prev, const Environment &  PrevEnv, Value &  Current, Environment &  CurrentEnv  )

inlinevirtual

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.

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.

Returns one of the folowing:

• std::nullopt, if this value is not of interest to the model.
• A WidenResult with:
  • A non-null Value * that points either to Current or a widened version of Current. This value must be consistent with the flow condition of CurrentEnv. We particularly caution against using Prev, which is rarely consistent.
  • A LatticeEffect indicating whether the value should be considered a new value (Changed) or one equivalent (if not necessarily equal) to Prev (Unchanged).

PrevEnv and CurrentEnv can be used to query child values and path condition implications of Prev and Current, respectively.

Requirements:

Prev and Current must model values of type Type.

Prev and Current must be assigned to the same storage location in PrevEnv and CurrentEnv, respectively.

Definition at line 138 of file DataflowEnvironment.h.

References clang::dataflow::Changed, compare(), clang::dataflow::Different, clang::dataflow::Same, clang::dataflow::Unchanged, and clang::dataflow::Unknown.

Referenced by clang::dataflow::widenDistinctValues().

---

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

• include/clang/Analysis/FlowSensitive/DataflowEnvironment.h