LLVM  16.0.0git
llvm::AbstractState Struct Referenceabstract

An interface to query the internal state of an abstract attribute. More...

#include "llvm/Transforms/IPO/Attributor.h"

Inheritance diagram for llvm::AbstractState:
[legend]

## Public Member Functions

virtual ~AbstractState ()=default

virtual bool isValidState () const =0
Return if this abstract state is in a valid state. More...

virtual bool isAtFixpoint () const =0
Return if this abstract state is fixed, thus does not need to be updated if information changes as it cannot change itself. More...

virtual ChangeStatus indicateOptimisticFixpoint ()=0
Indicate that the abstract state should converge to the optimistic state. More...

virtual ChangeStatus indicatePessimisticFixpoint ()=0
Indicate that the abstract state should converge to the pessimistic state. More...

## Detailed Description

An interface to query the internal state of an abstract attribute.

The abstract state is a minimal interface that allows the Attributor to communicate with the abstract attributes about their internal state without enforcing or exposing implementation details, e.g., the (existence of an) underlying lattice.

It is sufficient to be able to query if a state is (1) valid or invalid, (2) at a fixpoint, and to indicate to the state that (3) an optimistic fixpoint was reached or (4) a pessimistic fixpoint was enforced.

All methods need to be implemented by the subclass. For the common use case, a single boolean state or a bit-encoded state, the BooleanState and {Inc,Dec,Bit}IntegerState classes are already provided. An abstract attribute can inherit from them to get the abstract state interface and additional methods to directly modify the state based if needed. See the class comments for help.

Definition at line 2249 of file Attributor.h.

## ◆ ~AbstractState()

 virtual llvm::AbstractState::~AbstractState ( )
virtualdefault

## ◆ indicateOptimisticFixpoint()

 virtual ChangeStatus llvm::AbstractState::indicateOptimisticFixpoint ( )
pure virtual

Indicate that the abstract state should converge to the optimistic state.

This will usually make the optimistically assumed state the known to be true state.

Returns
ChangeStatus::UNCHANGED as the assumed value should not change.

## ◆ indicatePessimisticFixpoint()

 virtual ChangeStatus llvm::AbstractState::indicatePessimisticFixpoint ( )
pure virtual

Indicate that the abstract state should converge to the pessimistic state.

This will usually revert the optimistically assumed state to the known to be true state.

Returns
ChangeStatus::CHANGED as the assumed value may change.

## ◆ isAtFixpoint()

 virtual bool llvm::AbstractState::isAtFixpoint ( ) const
pure virtual

Return if this abstract state is fixed, thus does not need to be updated if information changes as it cannot change itself.

Referenced by llvm::Attributor::recordDependence().

## ◆ isValidState()

 virtual bool llvm::AbstractState::isValidState ( ) const
pure virtual

Return if this abstract state is in a valid state.

If false, no information provided should be used.

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