rustc_middle/mir/interpret/allocation.rs
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//! The virtual memory representation of the MIR interpreter.
mod init_mask;
mod provenance_map;
use std::borrow::Cow;
use std::hash::Hash;
use std::ops::{Deref, DerefMut, Range};
use std::{fmt, hash, ptr};
use either::{Left, Right};
use init_mask::*;
pub use init_mask::{InitChunk, InitChunkIter};
use provenance_map::*;
use rustc_abi::{Align, HasDataLayout, Size};
use rustc_ast::Mutability;
use rustc_data_structures::intern::Interned;
use rustc_macros::{HashStable, TyDecodable, TyEncodable};
use super::{
AllocId, BadBytesAccess, CtfeProvenance, InterpErrorKind, InterpResult, Pointer,
PointerArithmetic, Provenance, ResourceExhaustionInfo, Scalar, ScalarSizeMismatch,
UndefinedBehaviorInfo, UnsupportedOpInfo, interp_ok, read_target_uint, write_target_uint,
};
use crate::ty;
/// Functionality required for the bytes of an `Allocation`.
pub trait AllocBytes: Clone + fmt::Debug + Deref<Target = [u8]> + DerefMut<Target = [u8]> {
/// Create an `AllocBytes` from a slice of `u8`.
fn from_bytes<'a>(slice: impl Into<Cow<'a, [u8]>>, _align: Align) -> Self;
/// Create a zeroed `AllocBytes` of the specified size and alignment.
/// Returns `None` if we ran out of memory on the host.
fn zeroed(size: Size, _align: Align) -> Option<Self>;
/// Gives direct access to the raw underlying storage.
///
/// Crucially this pointer is compatible with:
/// - other pointers returned by this method, and
/// - references returned from `deref()`, as long as there was no write.
fn as_mut_ptr(&mut self) -> *mut u8;
/// Gives direct access to the raw underlying storage.
///
/// Crucially this pointer is compatible with:
/// - other pointers returned by this method, and
/// - references returned from `deref()`, as long as there was no write.
fn as_ptr(&self) -> *const u8;
}
/// Default `bytes` for `Allocation` is a `Box<u8>`.
impl AllocBytes for Box<[u8]> {
fn from_bytes<'a>(slice: impl Into<Cow<'a, [u8]>>, _align: Align) -> Self {
Box::<[u8]>::from(slice.into())
}
fn zeroed(size: Size, _align: Align) -> Option<Self> {
let bytes = Box::<[u8]>::try_new_zeroed_slice(size.bytes().try_into().ok()?).ok()?;
// SAFETY: the box was zero-allocated, which is a valid initial value for Box<[u8]>
let bytes = unsafe { bytes.assume_init() };
Some(bytes)
}
fn as_mut_ptr(&mut self) -> *mut u8 {
Box::as_mut_ptr(self).cast()
}
fn as_ptr(&self) -> *const u8 {
Box::as_ptr(self).cast()
}
}
/// 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.
// Note: for performance reasons when interning, some of the `Allocation` fields can be partially
// hashed. (see the `Hash` impl below for more details), so the impl is not derived.
#[derive(Clone, Eq, PartialEq, TyEncodable, TyDecodable)]
#[derive(HashStable)]
pub struct Allocation<Prov: Provenance = CtfeProvenance, Extra = (), Bytes = Box<[u8]>> {
/// The actual bytes of the allocation.
/// Note that the bytes of a pointer represent the offset of the pointer.
bytes: Bytes,
/// Maps from byte addresses to extra provenance 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.
provenance: ProvenanceMap<Prov>,
/// Denotes which part of this allocation is initialized.
init_mask: InitMask,
/// The alignment of the allocation to detect unaligned reads.
/// (`Align` guarantees that this is a power of two.)
pub align: Align,
/// `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.
pub mutability: Mutability,
/// Extra state for the machine.
pub extra: Extra,
}
/// This is the maximum size we will hash at a time, when interning an `Allocation` and its
/// `InitMask`. Note, we hash that amount of bytes twice: at the start, and at the end of a buffer.
/// Used when these two structures are large: we only partially hash the larger fields in that
/// situation. See the comment at the top of their respective `Hash` impl for more details.
const MAX_BYTES_TO_HASH: usize = 64;
/// This is the maximum size (in bytes) for which a buffer will be fully hashed, when interning.
/// Otherwise, it will be partially hashed in 2 slices, requiring at least 2 `MAX_BYTES_TO_HASH`
/// bytes.
const MAX_HASHED_BUFFER_LEN: usize = 2 * MAX_BYTES_TO_HASH;
// Const allocations are only hashed for interning. However, they can be large, making the hashing
// expensive especially since it uses `FxHash`: it's better suited to short keys, not potentially
// big buffers like the actual bytes of allocation. We can partially hash some fields when they're
// large.
impl hash::Hash for Allocation {
fn hash<H: hash::Hasher>(&self, state: &mut H) {
let Self {
bytes,
provenance,
init_mask,
align,
mutability,
extra: (), // don't bother hashing ()
} = self;
// Partially hash the `bytes` buffer when it is large. To limit collisions with common
// prefixes and suffixes, we hash the length and some slices of the buffer.
let byte_count = bytes.len();
if byte_count > MAX_HASHED_BUFFER_LEN {
// Hash the buffer's length.
byte_count.hash(state);
// And its head and tail.
bytes[..MAX_BYTES_TO_HASH].hash(state);
bytes[byte_count - MAX_BYTES_TO_HASH..].hash(state);
} else {
bytes.hash(state);
}
// Hash the other fields as usual.
provenance.hash(state);
init_mask.hash(state);
align.hash(state);
mutability.hash(state);
}
}
/// Interned types generally have an `Outer` type and an `Inner` type, where
/// `Outer` is a newtype around `Interned<Inner>`, and all the operations are
/// done on `Outer`, because all occurrences are interned. E.g. `Ty` is an
/// outer type and `TyKind` is its inner type.
///
/// Here things are different because only const allocations are interned. This
/// means that both the inner type (`Allocation`) and the outer type
/// (`ConstAllocation`) are used quite a bit.
#[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable)]
#[rustc_pass_by_value]
pub struct ConstAllocation<'tcx>(pub Interned<'tcx, Allocation>);
impl<'tcx> fmt::Debug for ConstAllocation<'tcx> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// The debug representation of this is very verbose and basically useless,
// so don't print it.
write!(f, "ConstAllocation {{ .. }}")
}
}
impl<'tcx> ConstAllocation<'tcx> {
pub fn inner(self) -> &'tcx Allocation {
self.0.0
}
}
/// We have our own error type that does not know about the `AllocId`; that information
/// is added when converting to `InterpError`.
#[derive(Debug)]
pub enum AllocError {
/// A scalar had the wrong size.
ScalarSizeMismatch(ScalarSizeMismatch),
/// Encountered a pointer where we needed raw bytes.
ReadPointerAsInt(Option<BadBytesAccess>),
/// Partially overwriting a pointer.
OverwritePartialPointer(Size),
/// Partially copying a pointer.
ReadPartialPointer(Size),
/// Using uninitialized data where it is not allowed.
InvalidUninitBytes(Option<BadBytesAccess>),
}
pub type AllocResult<T = ()> = Result<T, AllocError>;
impl From<ScalarSizeMismatch> for AllocError {
fn from(s: ScalarSizeMismatch) -> Self {
AllocError::ScalarSizeMismatch(s)
}
}
impl AllocError {
pub fn to_interp_error<'tcx>(self, alloc_id: AllocId) -> InterpErrorKind<'tcx> {
use AllocError::*;
match self {
ScalarSizeMismatch(s) => {
InterpErrorKind::UndefinedBehavior(UndefinedBehaviorInfo::ScalarSizeMismatch(s))
}
ReadPointerAsInt(info) => InterpErrorKind::Unsupported(
UnsupportedOpInfo::ReadPointerAsInt(info.map(|b| (alloc_id, b))),
),
OverwritePartialPointer(offset) => InterpErrorKind::Unsupported(
UnsupportedOpInfo::OverwritePartialPointer(Pointer::new(alloc_id, offset)),
),
ReadPartialPointer(offset) => InterpErrorKind::Unsupported(
UnsupportedOpInfo::ReadPartialPointer(Pointer::new(alloc_id, offset)),
),
InvalidUninitBytes(info) => InterpErrorKind::UndefinedBehavior(
UndefinedBehaviorInfo::InvalidUninitBytes(info.map(|b| (alloc_id, b))),
),
}
}
}
/// The information that makes up a memory access: offset and size.
#[derive(Copy, Clone)]
pub struct AllocRange {
pub start: Size,
pub size: Size,
}
impl fmt::Debug for AllocRange {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "[{:#x}..{:#x}]", self.start.bytes(), self.end().bytes())
}
}
/// Free-starting constructor for less syntactic overhead.
#[inline(always)]
pub fn alloc_range(start: Size, size: Size) -> AllocRange {
AllocRange { start, size }
}
impl From<Range<Size>> for AllocRange {
#[inline]
fn from(r: Range<Size>) -> Self {
alloc_range(r.start, r.end - r.start) // `Size` subtraction (overflow-checked)
}
}
impl From<Range<usize>> for AllocRange {
#[inline]
fn from(r: Range<usize>) -> Self {
AllocRange::from(Size::from_bytes(r.start)..Size::from_bytes(r.end))
}
}
impl AllocRange {
#[inline(always)]
pub fn end(self) -> Size {
self.start + self.size // This does overflow checking.
}
/// Returns the `subrange` within this range; panics if it is not a subrange.
#[inline]
pub fn subrange(self, subrange: AllocRange) -> AllocRange {
let sub_start = self.start + subrange.start;
let range = alloc_range(sub_start, subrange.size);
assert!(range.end() <= self.end(), "access outside the bounds for given AllocRange");
range
}
}
// The constructors are all without extra; the extra gets added by a machine hook later.
impl<Prov: Provenance, Bytes: AllocBytes> Allocation<Prov, (), Bytes> {
/// Creates an allocation initialized by the given bytes
pub fn from_bytes<'a>(
slice: impl Into<Cow<'a, [u8]>>,
align: Align,
mutability: Mutability,
) -> Self {
let bytes = Bytes::from_bytes(slice, align);
let size = Size::from_bytes(bytes.len());
Self {
bytes,
provenance: ProvenanceMap::new(),
init_mask: InitMask::new(size, true),
align,
mutability,
extra: (),
}
}
pub fn from_bytes_byte_aligned_immutable<'a>(slice: impl Into<Cow<'a, [u8]>>) -> Self {
Allocation::from_bytes(slice, Align::ONE, Mutability::Not)
}
fn uninit_inner<R>(size: Size, align: Align, fail: impl FnOnce() -> R) -> Result<Self, R> {
// We raise an error if we cannot create the allocation on the host.
// This results in an error that can happen non-deterministically, since the memory
// available to the compiler can change between runs. Normally queries are always
// deterministic. However, we can be non-deterministic here because all uses of const
// evaluation (including ConstProp!) will make compilation fail (via hard error
// or ICE) upon encountering a `MemoryExhausted` error.
let bytes = Bytes::zeroed(size, align).ok_or_else(fail)?;
Ok(Allocation {
bytes,
provenance: ProvenanceMap::new(),
init_mask: InitMask::new(size, false),
align,
mutability: Mutability::Mut,
extra: (),
})
}
/// Try to create an Allocation of `size` bytes, failing if there is not enough memory
/// available to the compiler to do so.
pub fn try_uninit<'tcx>(size: Size, align: Align) -> InterpResult<'tcx, Self> {
Self::uninit_inner(size, align, || {
ty::tls::with(|tcx| tcx.dcx().delayed_bug("exhausted memory during interpretation"));
InterpErrorKind::ResourceExhaustion(ResourceExhaustionInfo::MemoryExhausted)
})
.into()
}
/// Try to create an Allocation of `size` bytes, panics if there is not enough memory
/// available to the compiler to do so.
///
/// Example use case: To obtain an Allocation filled with specific data,
/// first call this function and then call write_scalar to fill in the right data.
pub fn uninit(size: Size, align: Align) -> Self {
match Self::uninit_inner(size, align, || {
panic!(
"interpreter ran out of memory: cannot create allocation of {} bytes",
size.bytes()
);
}) {
Ok(x) => x,
Err(x) => x,
}
}
/// Add the extra.
pub fn with_extra<Extra>(self, extra: Extra) -> Allocation<Prov, Extra, Bytes> {
Allocation {
bytes: self.bytes,
provenance: self.provenance,
init_mask: self.init_mask,
align: self.align,
mutability: self.mutability,
extra,
}
}
}
impl Allocation {
/// Adjust allocation from the ones in `tcx` to a custom Machine instance
/// with a different `Provenance` and `Byte` type.
pub fn adjust_from_tcx<'tcx, Prov: Provenance, Bytes: AllocBytes>(
&self,
cx: &impl HasDataLayout,
mut alloc_bytes: impl FnMut(&[u8], Align) -> InterpResult<'tcx, Bytes>,
mut adjust_ptr: impl FnMut(Pointer<CtfeProvenance>) -> InterpResult<'tcx, Pointer<Prov>>,
) -> InterpResult<'tcx, Allocation<Prov, (), Bytes>> {
// Copy the data.
let mut bytes = alloc_bytes(&*self.bytes, self.align)?;
// Adjust provenance of pointers stored in this allocation.
let mut new_provenance = Vec::with_capacity(self.provenance.ptrs().len());
let ptr_size = cx.data_layout().pointer_size.bytes_usize();
let endian = cx.data_layout().endian;
for &(offset, alloc_id) in self.provenance.ptrs().iter() {
let idx = offset.bytes_usize();
let ptr_bytes = &mut bytes[idx..idx + ptr_size];
let bits = read_target_uint(endian, ptr_bytes).unwrap();
let (ptr_prov, ptr_offset) =
adjust_ptr(Pointer::new(alloc_id, Size::from_bytes(bits)))?.into_parts();
write_target_uint(endian, ptr_bytes, ptr_offset.bytes().into()).unwrap();
new_provenance.push((offset, ptr_prov));
}
// Create allocation.
interp_ok(Allocation {
bytes,
provenance: ProvenanceMap::from_presorted_ptrs(new_provenance),
init_mask: self.init_mask.clone(),
align: self.align,
mutability: self.mutability,
extra: self.extra,
})
}
}
/// Raw accessors. Provide access to otherwise private bytes.
impl<Prov: Provenance, Extra, Bytes: AllocBytes> Allocation<Prov, Extra, Bytes> {
pub fn len(&self) -> usize {
self.bytes.len()
}
pub fn size(&self) -> Size {
Size::from_bytes(self.len())
}
/// Looks at a slice which may contain uninitialized bytes or provenance. This differs
/// from `get_bytes_with_uninit_and_ptr` in that it does no provenance checks (even on the
/// edges) at all.
/// This must not be used for reads affecting the interpreter execution.
pub fn inspect_with_uninit_and_ptr_outside_interpreter(&self, range: Range<usize>) -> &[u8] {
&self.bytes[range]
}
/// Returns the mask indicating which bytes are initialized.
pub fn init_mask(&self) -> &InitMask {
&self.init_mask
}
/// Returns the provenance map.
pub fn provenance(&self) -> &ProvenanceMap<Prov> {
&self.provenance
}
}
/// Byte accessors.
impl<Prov: Provenance, Extra, Bytes: AllocBytes> Allocation<Prov, Extra, Bytes> {
/// This is the entirely abstraction-violating way to just grab the raw bytes without
/// caring about provenance or initialization.
///
/// This function also guarantees that the resulting pointer will remain stable
/// even when new allocations are pushed to the `HashMap`. `mem_copy_repeatedly` relies
/// on that.
#[inline]
pub fn get_bytes_unchecked(&self, range: AllocRange) -> &[u8] {
&self.bytes[range.start.bytes_usize()..range.end().bytes_usize()]
}
/// Checks that these bytes are initialized, and then strip provenance (if possible) and return
/// them.
///
/// 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.
#[inline]
pub fn get_bytes_strip_provenance(
&self,
cx: &impl HasDataLayout,
range: AllocRange,
) -> AllocResult<&[u8]> {
self.init_mask.is_range_initialized(range).map_err(|uninit_range| {
AllocError::InvalidUninitBytes(Some(BadBytesAccess {
access: range,
bad: uninit_range,
}))
})?;
if !Prov::OFFSET_IS_ADDR && !self.provenance.range_empty(range, cx) {
// Find the provenance.
let (offset, _prov) = self
.provenance
.range_get_ptrs(range, cx)
.first()
.copied()
.expect("there must be provenance somewhere here");
let start = offset.max(range.start); // the pointer might begin before `range`!
let end = (offset + cx.pointer_size()).min(range.end()); // the pointer might end after `range`!
return Err(AllocError::ReadPointerAsInt(Some(BadBytesAccess {
access: range,
bad: AllocRange::from(start..end),
})));
}
Ok(self.get_bytes_unchecked(range))
}
/// This is the entirely abstraction-violating way to just get mutable access to the raw bytes.
/// Just calling this already marks everything as defined and removes provenance, so be sure to
/// actually overwrite all the 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_unchecked_for_overwrite(
&mut self,
cx: &impl HasDataLayout,
range: AllocRange,
) -> AllocResult<&mut [u8]> {
self.mark_init(range, true);
self.provenance.clear(range, cx)?;
Ok(&mut self.bytes[range.start.bytes_usize()..range.end().bytes_usize()])
}
/// A raw pointer variant of `get_bytes_unchecked_for_overwrite` that avoids invalidating existing immutable aliases
/// into this memory.
pub fn get_bytes_unchecked_for_overwrite_ptr(
&mut self,
cx: &impl HasDataLayout,
range: AllocRange,
) -> AllocResult<*mut [u8]> {
self.mark_init(range, true);
self.provenance.clear(range, cx)?;
assert!(range.end().bytes_usize() <= self.bytes.len()); // need to do our own bounds-check
// Crucially, we go via `AllocBytes::as_mut_ptr`, not `AllocBytes::deref_mut`.
let begin_ptr = self.bytes.as_mut_ptr().wrapping_add(range.start.bytes_usize());
let len = range.end().bytes_usize() - range.start.bytes_usize();
Ok(ptr::slice_from_raw_parts_mut(begin_ptr, len))
}
/// This gives direct mutable access to the entire buffer, just exposing their internal state
/// without resetting anything. Directly exposes `AllocBytes::as_mut_ptr`. Only works if
/// `OFFSET_IS_ADDR` is true.
pub fn get_bytes_unchecked_raw_mut(&mut self) -> *mut u8 {
assert!(Prov::OFFSET_IS_ADDR);
self.bytes.as_mut_ptr()
}
/// This gives direct immutable access to the entire buffer, just exposing their internal state
/// without resetting anything. Directly exposes `AllocBytes::as_ptr`. Only works if
/// `OFFSET_IS_ADDR` is true.
pub fn get_bytes_unchecked_raw(&self) -> *const u8 {
assert!(Prov::OFFSET_IS_ADDR);
self.bytes.as_ptr()
}
}
/// Reading and writing.
impl<Prov: Provenance, Extra, Bytes: AllocBytes> Allocation<Prov, Extra, Bytes> {
/// Sets the init bit for the given range.
fn mark_init(&mut self, range: AllocRange, is_init: bool) {
if range.size.bytes() == 0 {
return;
}
assert!(self.mutability == Mutability::Mut);
self.init_mask.set_range(range, is_init);
}
/// Reads a *non-ZST* scalar.
///
/// If `read_provenance` is `true`, this will also read provenance; otherwise (if the machine
/// supports that) provenance is entirely ignored.
///
/// 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 read_scalar(
&self,
cx: &impl HasDataLayout,
range: AllocRange,
read_provenance: bool,
) -> AllocResult<Scalar<Prov>> {
// First and foremost, if anything is uninit, bail.
if self.init_mask.is_range_initialized(range).is_err() {
return Err(AllocError::InvalidUninitBytes(None));
}
// Get the integer part of the result. We HAVE TO check provenance before returning this!
let bytes = self.get_bytes_unchecked(range);
let bits = read_target_uint(cx.data_layout().endian, bytes).unwrap();
if read_provenance {
assert_eq!(range.size, cx.data_layout().pointer_size);
// When reading data with provenance, the easy case is finding provenance exactly where we
// are reading, then we can put data and provenance back together and return that.
if let Some(prov) = self.provenance.get_ptr(range.start) {
// Now we can return the bits, with their appropriate provenance.
let ptr = Pointer::new(prov, Size::from_bytes(bits));
return Ok(Scalar::from_pointer(ptr, cx));
}
// If we can work on pointers byte-wise, join the byte-wise provenances.
if Prov::OFFSET_IS_ADDR {
let mut prov = self.provenance.get(range.start, cx);
for offset in Size::from_bytes(1)..range.size {
let this_prov = self.provenance.get(range.start + offset, cx);
prov = Prov::join(prov, this_prov);
}
// Now use this provenance.
let ptr = Pointer::new(prov, Size::from_bytes(bits));
return Ok(Scalar::from_maybe_pointer(ptr, cx));
} else {
// Without OFFSET_IS_ADDR, the only remaining case we can handle is total absence of
// provenance.
if self.provenance.range_empty(range, cx) {
return Ok(Scalar::from_uint(bits, range.size));
}
// Else we have mixed provenance, that doesn't work.
return Err(AllocError::ReadPartialPointer(range.start));
}
} else {
// We are *not* reading a pointer.
// If we can just ignore provenance or there is none, that's easy.
if Prov::OFFSET_IS_ADDR || self.provenance.range_empty(range, cx) {
// We just strip provenance.
return Ok(Scalar::from_uint(bits, range.size));
}
// There is some provenance and we don't have OFFSET_IS_ADDR. This doesn't work.
return Err(AllocError::ReadPointerAsInt(None));
}
}
/// 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.
pub fn write_scalar(
&mut self,
cx: &impl HasDataLayout,
range: AllocRange,
val: Scalar<Prov>,
) -> AllocResult {
assert!(self.mutability == Mutability::Mut);
// `to_bits_or_ptr_internal` is the right method because we just want to store this data
// as-is into memory. This also double-checks that `val.size()` matches `range.size`.
let (bytes, provenance) = match val.to_bits_or_ptr_internal(range.size)? {
Right(ptr) => {
let (provenance, offset) = ptr.into_parts();
(u128::from(offset.bytes()), Some(provenance))
}
Left(data) => (data, None),
};
let endian = cx.data_layout().endian;
// Yes we do overwrite all the bytes in `dst`.
let dst = self.get_bytes_unchecked_for_overwrite(cx, range)?;
write_target_uint(endian, dst, bytes).unwrap();
// See if we have to also store some provenance.
if let Some(provenance) = provenance {
assert_eq!(range.size, cx.data_layout().pointer_size);
self.provenance.insert_ptr(range.start, provenance, cx);
}
Ok(())
}
/// Write "uninit" to the given memory range.
pub fn write_uninit(&mut self, cx: &impl HasDataLayout, range: AllocRange) -> AllocResult {
self.mark_init(range, false);
self.provenance.clear(range, cx)?;
Ok(())
}
/// Remove all provenance in the given memory range.
pub fn clear_provenance(&mut self, cx: &impl HasDataLayout, range: AllocRange) -> AllocResult {
self.provenance.clear(range, cx)?;
return Ok(());
}
/// Applies a previously prepared provenance copy.
/// The affected range, as defined in the parameters to `provenance().prepare_copy` is expected
/// to be clear of provenance.
///
/// This is dangerous to use as it can violate internal `Allocation` invariants!
/// It only exists to support an efficient implementation of `mem_copy_repeatedly`.
pub fn provenance_apply_copy(&mut self, copy: ProvenanceCopy<Prov>) {
self.provenance.apply_copy(copy)
}
/// Applies a previously prepared copy of the init mask.
///
/// This is dangerous to use as it can violate internal `Allocation` invariants!
/// It only exists to support an efficient implementation of `mem_copy_repeatedly`.
pub fn init_mask_apply_copy(&mut self, copy: InitCopy, range: AllocRange, repeat: u64) {
self.init_mask.apply_copy(copy, range, repeat)
}
}