llvm::PoisoningVH< ValueTy > Class Template Reference

Value handle that poisons itself if the Value is deleted. More...

#include "llvm/IR/ValueHandle.h"

Inheritance diagram for llvm::PoisoningVH< ValueTy >:

Public Member Functions
	PoisoningVH ()=default
	PoisoningVH (ValueTy *P)
	operator ValueTy * () const
ValueTy *	operator-> () const
ValueTy &	operator* () const

Friends
struct	DenseMapInfo< PoisoningVH< ValueTy > >

Detailed Description

template<typename ValueTy>
class llvm::PoisoningVH< ValueTy >

Value handle that poisons itself if the Value is deleted.

This is a Value Handle that points to a value and poisons itself if the value is destroyed while the handle is still live. This is very useful for catching dangling pointer bugs where an AssertingVH cannot be used because the dangling handle needs to outlive the value without ever being used.

One particularly useful place to use this is as the Key of a map. Dangling pointer bugs often lead to really subtle bugs that only occur if another object happens to get allocated to the same address as the old one. Using a PoisoningVH ensures that an assert is triggered if looking up a new value in the map finds a handle from the old value.

Note that a PoisoningVH handle does not follow values across RAUW operations. This means that RAUW's need to explicitly update the PoisoningVH's as it moves. This is required because in non-assert mode this class turns into a trivial wrapper around a pointer.

Definition at line 445 of file ValueHandle.h.

Constructor & Destructor Documentation

PoisoningVH() [1/2]

template<typename ValueTy >

llvm::PoisoningVH< ValueTy >::PoisoningVH ( )

default

PoisoningVH() [2/2]

template<typename ValueTy >

llvm::PoisoningVH< ValueTy >::PoisoningVH ( ValueTy *  P )

inline

Definition at line 516 of file ValueHandle.h.

Member Function Documentation

operator ValueTy *()

template<typename ValueTy >

llvm::PoisoningVH< ValueTy >::operator ValueTy * ( ) const

inline

Definition at line 519 of file ValueHandle.h.

operator*()

template<typename ValueTy >

ValueTy & llvm::PoisoningVH< ValueTy >::operator* ( ) const

inline

Definition at line 522 of file ValueHandle.h.

operator->()

template<typename ValueTy >

ValueTy * llvm::PoisoningVH< ValueTy >::operator-> ( ) const

inline

Definition at line 521 of file ValueHandle.h.

Friends And Related Function Documentation

DenseMapInfo< PoisoningVH< ValueTy > >

template<typename ValueTy >

friend struct DenseMapInfo< PoisoningVH< ValueTy > >

friend

Definition at line 423 of file ValueHandle.h.

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

• include/llvm/IR/ValueHandle.h