# Struct miri::Tree

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    pub struct Tree {
        pub(super) tag_mapping: UniKeyMap<BorTag>,
        pub(super) nodes: UniValMap<Node>,
        pub(super) rperms: RangeMap<UniValMap<LocationState>>,
        pub(super) root: UniIndex,
    }

Expand description

Tree structure with both parents and children since we want to be able to traverse the tree efficiently in both directions.

## Fields§

§`tag_mapping: UniKeyMap<BorTag>`

Mapping from tags to keys. The key obtained can then be used in any of the `UniValMap` relative to this allocation, i.e. both the `nodes` and `rperms` of the same `Tree`. The parent-child relationship in `Node` is encoded in terms of these same keys, so traversing the entire tree needs exactly one access to `tag_mapping`.

§`nodes: UniValMap<Node>`

All nodes of this tree.

§`rperms: RangeMap<UniValMap<LocationState>>`

Maps a tag and a location to a perm, with possible lazy initialization.

NOTE: not all tags registered in `nodes` are necessarily in all ranges of `rperms`, because `rperms` is in part lazily initialized. Just because `nodes.get(key)` is `Some(_)` does not mean you can safely `unwrap` any `perm.get(key)`.

We do uphold the fact that `keys(perms)` is a subset of `keys(nodes)`

§`root: UniIndex`

The index of the root node.

## Implementations§

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### impl<'tcx> Tree

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#### fn nth_parent(&self, tag: BorTag, nth_parent: u8) -> Option<BorTag>

Climb the tree to get the tag of a distant ancestor. Allows operations on tags that are unreachable by the program but still exist in the tree. Not guaranteed to perform consistently if `provenance-gc=1`.

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#### pub fn give_pointer_debug_name( &mut self, tag: BorTag, nth_parent: u8, name: &str ) -> InterpResult<'tcx>

Debug helper: assign name to tag.

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#### pub fn is_allocation_of(&self, tag: BorTag) -> bool

Debug helper: determines if the tree contains a tag.

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### impl<'tcx> Tree

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#### pub fn print_tree( &self, protected_tags: &FxHashMap<BorTag, ProtectorKind>, show_unnamed: bool ) -> InterpResult<'tcx>

Display the contents of the tree.

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### impl Tree

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#### pub fn new(root_tag: BorTag, size: Size, span: Span) -> Self

Create a new tree, with only a root pointer.

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### impl<'tcx> Tree

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#### pub fn new_child( &mut self, parent_tag: BorTag, new_tag: BorTag, default_initial_perm: Permission, reborrow_range: AllocRange, span: Span ) -> InterpResult<'tcx>

Insert a new tag in the tree

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#### pub fn dealloc( &mut self, tag: BorTag, access_range: AllocRange, global: &RefCell<GlobalStateInner>, alloc_id: AllocId, span: Span ) -> InterpResult<'tcx>

Deallocation requires

- a pointer that permits write accesses
- the absence of Strong Protectors anywhere in the allocation

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#### pub fn perform_access( &mut self, access_kind: AccessKind, tag: BorTag, access_range: Option<AllocRange>, global: &RefCell<GlobalStateInner>, alloc_id: AllocId, span: Span, access_cause: AccessCause ) -> InterpResult<'tcx>

Map the per-node and per-location `LocationState::perform_access` to each location of `access_range`, on every tag of the allocation.

If `access_range` is `None`, this is interpreted as the special access that is applied on protector release:

- the access will be applied only to initialized locations of the allocation,
- and it will not be visible to children.

`LocationState::perform_access` will take care of raising transition errors and updating the `initialized` status of each location, this traversal adds to that:

- inserting into the map locations that do not exist yet,
- trimming the traversal,
- recording the history.

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### impl Tree

Integration with the BorTag garbage collector

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#### pub fn remove_unreachable_tags(&mut self, live_tags: &FxHashSet<BorTag>)

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#### fn keep_only_needed(&mut self, idx: UniIndex, live: &FxHashSet<BorTag>) -> bool

Traverses the entire tree looking for useless tags. Returns true iff the tag it was called on is still live or has live children, and removes from the tree all tags that have no live children.

NOTE: This leaves in the middle of the tree tags that are unreachable but have reachable children. There is a potential for compacting the tree by reassigning children of dead tags to the nearest live parent, but it must be done with care not to remove UB.

Example: Consider the tree `root - parent - child`, with `parent: Frozen` and `child: Reserved`. This tree can exist. If we blindly delete `parent` and reassign `child` to be a direct child of `root` then Writes to `child` are now permitted whereas they were not when `parent` was still there.

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### impl<'tcx> Tree

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#### pub fn new_allocation( id: AllocId, size: Size, state: &mut GlobalStateInner, _kind: MemoryKind, machine: &MiriMachine<'_, 'tcx> ) -> Self

Create a new allocation, i.e. a new tree

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#### pub fn before_memory_access( &mut self, access_kind: AccessKind, alloc_id: AllocId, prov: ProvenanceExtra, range: AllocRange, machine: &MiriMachine<'_, 'tcx> ) -> InterpResult<'tcx>

Check that an access on the entire range is permitted, and update the tree.

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#### pub fn before_memory_deallocation( &mut self, alloc_id: AllocId, prov: ProvenanceExtra, size: Size, machine: &MiriMachine<'_, 'tcx> ) -> InterpResult<'tcx>

Check that this pointer has permission to deallocate this range.

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#### pub fn expose_tag(&mut self, _tag: BorTag)

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#### pub fn release_protector( &mut self, machine: &MiriMachine<'_, 'tcx>, global: &RefCell<GlobalStateInner>, tag: BorTag, alloc_id: AllocId ) -> InterpResult<'tcx>

A tag just lost its protector.

This emits a special kind of access that is only applied to initialized locations, as a protection against other tags not having been made aware of the existence of this protector.

## Trait Implementations§

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### impl Clone for Tree

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#### fn clone(&self) -> Tree

Returns a copy of the value. Read more
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#### fn clone_from(&mut self, source: &Self)

Performs copy-assignment from `source`. Read more
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### impl Debug for Tree

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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### impl VisitProvenance for Tree

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#### fn visit_provenance(&self, visit: &mut VisitWith<'_>)

## Auto Trait Implementations§

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### impl !DynSend for Tree

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### impl !DynSync for Tree

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### impl Freeze for Tree

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### impl RefUnwindSafe for Tree

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### impl Send for Tree

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### impl Sync for Tree

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### impl Unpin for Tree

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### impl UnwindSafe for Tree

## Blanket Implementations§

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### impl<T> Aligned for T

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#### const ALIGN: Alignment = _

Alignment of `Self`.
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### impl<T> Any for T
where T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Borrow<T> for T
where T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for T
where T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T, R> CollectAndApply<T, R> for T

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#### fn collect_and_apply<I, F>(iter: I, f: F) -> R
where I: Iterator<Item = T>, F: FnOnce(&[T]) -> R,

Equivalent to `f(&iter.collect::<Vec<_>>())`.

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#### type Output = R

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### impl<T> Filterable for T

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#### fn filterable( self, filter_name: &'static str ) -> RequestFilterDataProvider<T, fn(_: DataRequest<'_>) -> bool>

Creates a filterable data provider with the given name for debugging. Read more
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T> Instrument for T

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#### fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided `Span`, returning an `Instrumented` wrapper. Read more
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#### fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current `Span`, returning an `Instrumented` wrapper. Read more
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### impl<T, U> Into<U> for T
where U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<P> IntoQueryParam<P> for P

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#### fn into_query_param(self) -> P

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### impl<T> MaybeResult<T> for T

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#### type Error = !

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#### fn from(_: Result<T, <T as MaybeResult<T>>::Error>) -> T

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#### fn to_result(self) -> Result<T, <T as MaybeResult<T>>::Error>

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### impl<T> Pointable for T

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#### const ALIGN: usize = _

The alignment of pointer.
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#### type Init = T

The type for initializers.
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#### unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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#### unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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#### unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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#### unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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### impl<T> Same for T

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#### type Output = T

Should always be `Self`
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### impl<T> Same for T

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#### type Output = T

Should always be `Self`
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### impl<T> ToOwned for T
where T: Clone,

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#### type Owned = T

The resulting type after obtaining ownership.
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#### fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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#### fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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### impl<'tcx, T> ToPredicate<'tcx, T> for T

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#### fn to_predicate(self, _tcx: TyCtxt<'tcx>) -> T

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### impl<T, U> TryFrom<U> for T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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### impl<V, T> VZip<V> for T
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#### fn vzip(self) -> V

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### impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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#### fn vzip(self) -> V

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### impl<Tcx, T> Value<Tcx> for T
where Tcx: DepContext,

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#### default fn from_cycle_error( tcx: Tcx, cycle_error: &CycleError, _guar: ErrorGuaranteed ) -> T

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### impl<T> WithSubscriber for T

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#### fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided `Subscriber` to this type, returning a `WithDispatch` wrapper. Read more
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Attaches the current default `Subscriber` to this type, returning a `WithDispatch` wrapper. Read more
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### impl<'a, T> Captures<'a> for T
where T: ?Sized,

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### impl<'a, T> Captures<'a> for T
where T: ?Sized,

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### impl<T> ErasedDestructor for T
where T: 'static,

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### impl<T> MaybeSendSync for T
where T: Send + Sync,

## Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain `repr(...)` attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 112 bytes