Struct rustc_middle::mir::interpret::allocation::Allocation

pub struct Allocation<Tag = AllocId, Extra = ()> {
    bytes: Box<[u8]>,
    relocations: Relocations<Tag>,
    init_mask: InitMask,
    pub align: Align,
    pub mutability: Mutability,
    pub extra: Extra,
}

This type represents an Allocation in the Miri/CTFE core engine.

Its public API is rather low-level, working directly with allocation offsets and a custom error type to account for the lack of an AllocId on this level. The Miri/CTFE core engine memory module provides higher-level access.

Fields

bytes: Box<[u8]>

The actual bytes of the allocation. Note that the bytes of a pointer represent the offset of the pointer.

relocations: Relocations<Tag>

Maps from byte addresses to extra data for each pointer. Only the first byte of a pointer is inserted into the map; i.e., every entry in this map applies to pointer_size consecutive bytes starting at the given offset.

init_mask: InitMask

Denotes which part of this allocation is initialized.

align: Align

The alignment of the allocation to detect unaligned reads. (Align guarantees that this is a power of two.)

mutability: Mutability

true if the allocation is mutable. Also used by codegen to determine if a static should be put into mutable memory, which happens for static mut and static with interior mutability.

extra: Extra

Extra state for the machine.

Implementations

impl<Tag> Allocation<Tag>

pub fn from_bytes<'a>(
    slice: impl Into<Cow<'a, [u8]>>,
    align: Align,
    mutability: Mutability
) -> Self

Creates an allocation initialized by the given bytes

pub fn from_bytes_byte_aligned_immutable<'a>(
    slice: impl Into<Cow<'a, [u8]>>
) -> Self

pub fn uninit(
    size: Size,
    align: Align,
    panic_on_fail: bool
) -> InterpResult<'static, Self>

Try to create an Allocation of size bytes, failing if there is not enough memory available to the compiler to do so.

impl Allocation

pub fn convert_tag_add_extra<Tag, Extra>(
    self,
    cx: &impl HasDataLayout,
    extra: Extra,
    tagger: impl FnMut(Pointer<AllocId>) -> Pointer<Tag>
) -> Allocation<Tag, Extra>

Convert Tag and add Extra fields

impl<Tag, Extra> Allocation<Tag, Extra>

Raw accessors. Provide access to otherwise private bytes.

pub fn len(&self) -> usize

pub fn size(&self) -> Size

pub fn inspect_with_uninit_and_ptr_outside_interpreter(
    &self,
    range: Range<usize>
) -> &[u8]

Looks at a slice which may describe uninitialized bytes or describe a relocation. This differs from get_bytes_with_uninit_and_ptr in that it does no relocation checks (even on the edges) at all. This must not be used for reads affecting the interpreter execution.

pub fn init_mask(&self) -> &InitMask

Returns the mask indicating which bytes are initialized.

pub fn relocations(&self) -> &Relocations<Tag>

Returns the relocation list.

impl<Tag: Provenance, Extra> Allocation<Tag, Extra>

Byte accessors.

fn get_bytes_internal(
    &self,
    cx: &impl HasDataLayout,
    range: AllocRange,
    check_init_and_ptr: bool
) -> Result<&[u8], AllocError>

The last argument controls whether we error out when there are uninitialized or pointer bytes. You should never call this, call get_bytes or get_bytes_with_uninit_and_ptr instead,

This function also guarantees that the resulting pointer will remain stable even when new allocations are pushed to the HashMap. copy_repeatedly relies on that.

It is the caller’s responsibility to check bounds and alignment beforehand.

pub fn get_bytes(
    &self,
    cx: &impl HasDataLayout,
    range: AllocRange
) -> Result<&[u8], AllocError>

Checks that these bytes are initialized and not pointer bytes, and then return them as a slice.

It is the caller’s responsibility to check bounds and alignment beforehand. Most likely, you want to use the PlaceTy and OperandTy-based methods on InterpCx instead.

pub fn get_bytes_with_uninit_and_ptr(
    &self,
    cx: &impl HasDataLayout,
    range: AllocRange
) -> Result<&[u8], AllocError>

It is the caller’s responsibility to handle uninitialized and pointer bytes. However, this still checks that there are no relocations on the edges.

It is the caller’s responsibility to check bounds and alignment beforehand.

pub fn get_bytes_mut(
    &mut self,
    cx: &impl HasDataLayout,
    range: AllocRange
) -> Result<&mut [u8], AllocError>

Just calling this already marks everything as defined and removes relocations, so be sure to actually put data there!

It is the caller’s responsibility to check bounds and alignment beforehand. Most likely, you want to use the PlaceTy and OperandTy-based methods on InterpCx instead.

pub fn get_bytes_mut_ptr(
    &mut self,
    cx: &impl HasDataLayout,
    range: AllocRange
) -> Result<*mut [u8], AllocError>

A raw pointer variant of get_bytes_mut that avoids invalidating existing aliases into this memory.

impl<Tag: Provenance, Extra> Allocation<Tag, Extra>

Reading and writing.

pub fn check_bytes(
    &self,
    cx: &impl HasDataLayout,
    range: AllocRange,
    allow_uninit_and_ptr: bool
) -> Result<(), AllocError>

Validates that ptr.offset and ptr.offset + size do not point to the middle of a relocation. If allow_uninit_and_ptr is false, also enforces that the memory in the given range contains neither relocations nor uninitialized bytes.

pub fn read_scalar(
    &self,
    cx: &impl HasDataLayout,
    range: AllocRange
) -> Result<ScalarMaybeUninit<Tag>, AllocError>

Reads a non-ZST scalar.

ZSTs can’t be read because in order to obtain a Pointer, we need to check for ZSTness anyway due to integer pointers being valid for ZSTs.

It is the caller’s responsibility to check bounds and alignment beforehand. Most likely, you want to call InterpCx::read_scalar instead of this method.

pub fn write_scalar(
    &mut self,
    cx: &impl HasDataLayout,
    range: AllocRange,
    val: ScalarMaybeUninit<Tag>
) -> Result<(), AllocError>

Writes a non-ZST scalar.

ZSTs can’t be read because in order to obtain a Pointer, we need to check for ZSTness anyway due to integer pointers being valid for ZSTs.

It is the caller’s responsibility to check bounds and alignment beforehand. Most likely, you want to call InterpCx::write_scalar instead of this method.

impl<Tag: Copy, Extra> Allocation<Tag, Extra>

Relocations.

pub fn get_relocations(
    &self,
    cx: &impl HasDataLayout,
    range: AllocRange
) -> &[(Size, Tag)]

Returns all relocations overlapping with the given pointer-offset pair.

fn check_relocations(
    &self,
    cx: &impl HasDataLayout,
    range: AllocRange
) -> Result<(), AllocError>

Checks that there are no relocations overlapping with the given range.

fn clear_relocations(
    &mut self,
    cx: &impl HasDataLayout,
    range: AllocRange
) -> Result<(), AllocError> where
    Tag: Provenance, 

Removes all relocations inside the given range. If there are relocations overlapping with the edges, they are removed as well and the bytes they cover are marked as uninitialized. This is a somewhat odd “spooky action at a distance”, but it allows strictly more code to run than if we would just error immediately in that case.

fn check_relocation_edges(
    &self,
    cx: &impl HasDataLayout,
    range: AllocRange
) -> Result<(), AllocError>

Errors if there are relocations overlapping with the edges of the given memory range.

impl<Tag: Copy, Extra> Allocation<Tag, Extra>

pub fn prepare_relocation_copy(
    &self,
    cx: &impl HasDataLayout,
    src: AllocRange,
    dest: Size,
    count: u64
) -> AllocationRelocations<Tag>

pub fn mark_relocation_range(&mut self, relocations: AllocationRelocations<Tag>)

Applies a relocation copy. The affected range, as defined in the parameters to prepare_relocation_copy is expected to be clear of relocations.

impl<Tag: Copy, Extra> Allocation<Tag, Extra>

Uninitialized bytes.

fn is_init(&self, range: AllocRange) -> Result<(), Range<Size>>

Checks whether the given range is entirely initialized.

Returns Ok(()) if it’s initialized. Otherwise returns the range of byte indexes of the first contiguous uninitialized access.

fn check_init(&self, range: AllocRange) -> Result<(), AllocError>

Checks that a range of bytes is initialized. If not, returns the InvalidUninitBytes error which will report the first range of bytes which is uninitialized.

pub fn mark_init(&mut self, range: AllocRange, is_init: bool)

impl<Tag, Extra> Allocation<Tag, Extra>

Transferring the initialization mask to other allocations.

pub fn compress_uninit_range(&self, range: AllocRange) -> InitMaskCompressed

Creates a run-length encoding of the initialization mask; panics if range is empty.

This is essentially a more space-efficient version of InitMask::range_as_init_chunks(...).collect::<Vec<_>>().

pub fn mark_compressed_init_range(
    &mut self,
    defined: &InitMaskCompressed,
    range: AllocRange,
    repeat: u64
)

Applies multiple instances of the run-length encoding to the initialization mask.

Trait Implementations

impl<'tcx> ArenaAllocatable<'tcx, IsNotCopy> for Allocation

fn allocate_on<'a>(self, arena: &'a Arena<'tcx>) -> &'a mut Self

fn allocate_from_iter<'a>(
    arena: &'a Arena<'tcx>,
    iter: impl IntoIterator<Item = Self>
) -> &'a mut [Self]

impl<'tcx> Borrow<Allocation<AllocId, ()>> for Interned<'tcx, Allocation>

fn borrow<'a>(&'a self) -> &'a Allocation

Immutably borrows from an owned value.

impl<Tag: Clone, Extra: Clone> Clone for Allocation<Tag, Extra>

fn clone(&self) -> Allocation<Tag, Extra>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<Tag: Debug, Extra: Debug> Debug for Allocation<Tag, Extra>

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

Formats the value using the given formatter.

impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for &'tcx Allocation

fn decode(decoder: &mut D) -> Self

impl<'tcx, Tag, Extra, __D: TyDecoder<'tcx>> Decodable<__D> for Allocation<Tag, Extra> where
    Tag: Decodable<__D>,
    Extra: Decodable<__D>, 

fn decode(__decoder: &mut __D) -> Self

impl<'tcx, Tag, Extra, __E: TyEncoder<'tcx>> Encodable<__E> for Allocation<Tag, Extra> where
    Tag: Encodable<__E>,
    Extra: Encodable<__E>, 

fn encode(&self, __encoder: &mut __E) -> Result<(), <__E as Encoder>::Error>

impl<Tag: Hash, Extra: Hash> Hash for Allocation<Tag, Extra>

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given Hasher.

impl<'__ctx, Tag, Extra> HashStable<StableHashingContext<'__ctx>> for Allocation<Tag, Extra> where
    Tag: HashStable<StableHashingContext<'__ctx>>,
    Extra: HashStable<StableHashingContext<'__ctx>>, 

fn hash_stable(
    &self,
    __hcx: &mut StableHashingContext<'__ctx>,
    __hasher: &mut StableHasher
)

impl<'a, 'tcx> Lift<'tcx> for &'a Allocation

type Lifted = &'tcx Allocation

fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted>

impl<Tag: Ord, Extra: Ord> Ord for Allocation<Tag, Extra>

fn cmp(&self, other: &Allocation<Tag, Extra>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl<Tag: PartialEq, Extra: PartialEq> PartialEq<Allocation<Tag, Extra>> for Allocation<Tag, Extra>

fn eq(&self, other: &Allocation<Tag, Extra>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Allocation<Tag, Extra>) -> bool

This method tests for !=.

impl<Tag: PartialOrd, Extra: PartialOrd> PartialOrd<Allocation<Tag, Extra>> for Allocation<Tag, Extra>

fn partial_cmp(&self, other: &Allocation<Tag, Extra>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<'tcx, D: TyDecoder<'tcx>> RefDecodable<'tcx, D> for Allocation

fn decode(decoder: &mut D) -> &'tcx Self

impl<Tag: Eq, Extra: Eq> Eq for Allocation<Tag, Extra>

impl<Tag, Extra> StructuralEq for Allocation<Tag, Extra>

impl<Tag, Extra> StructuralPartialEq for Allocation<Tag, Extra>

Layout

Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.