Merging upstream version 1.67.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 76 insertions, 773 deletions

diff --git a/compiler/rustc_middle/src/mir/interpret/allocation.rs b/compiler/rustc_middle/src/mir/interpret/allocation.rs
index 37ec04b07..221105ac4 100644
--- a/compiler/rustc_middle/src/mir/interpret/allocation.rs
+++ b/compiler/rustc_middle/src/mir/interpret/allocation.rs
@@ -1,16 +1,20 @@
 //! The virtual memory representation of the MIR interpreter.
 
+mod init_mask;
+mod provenance_map;
+#[cfg(test)]
+mod tests;
+
 use std::borrow::Cow;
-use std::convert::{TryFrom, TryInto};
 use std::fmt;
 use std::hash;
-use std::iter;
-use std::ops::{Deref, Range};
+use std::ops::Range;
 use std::ptr;
 
+use either::{Left, Right};
+
 use rustc_ast::Mutability;
 use rustc_data_structures::intern::Interned;
-use rustc_data_structures::sorted_map::SortedMap;
 use rustc_span::DUMMY_SP;
 use rustc_target::abi::{Align, HasDataLayout, Size};
 
@@ -20,6 +24,10 @@ use super::{
     UnsupportedOpInfo,
 };
 use crate::ty;
+use init_mask::*;
+use provenance_map::*;
+
+pub use init_mask::{InitChunk, InitChunkIter};
 
 /// This type represents an Allocation in the Miri/CTFE core engine.
 ///
@@ -28,9 +36,9 @@ use crate::ty;
 /// 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, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable)]
+#[derive(Clone, Eq, PartialEq, TyEncodable, TyDecodable)]
 #[derive(HashStable)]
-pub struct Allocation<Prov = AllocId, Extra = ()> {
+pub struct Allocation<Prov: Provenance = AllocId, Extra = ()> {
     /// The actual bytes of the allocation.
     /// Note that the bytes of a pointer represent the offset of the pointer.
     bytes: Box<[u8]>,
@@ -95,27 +103,25 @@ impl hash::Hash for Allocation {
 /// 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 `TyS` is its inner type.
+/// 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, PartialOrd, Ord, Hash, HashStable)]
+#[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable)]
 #[rustc_pass_by_value]
-pub struct ConstAllocation<'tcx, Prov = AllocId, Extra = ()>(
-    pub Interned<'tcx, Allocation<Prov, Extra>>,
-);
+pub struct ConstAllocation<'tcx>(pub Interned<'tcx, Allocation>);
 
 impl<'tcx> fmt::Debug for ConstAllocation<'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        // This matches how `Allocation` is printed. We print it like this to
-        // avoid having to update expected output in a lot of tests.
-        write!(f, "{:?}", self.inner())
+        // The debug representation of this is very verbose and basically useless,
+        // so don't print it.
+        write!(f, "ConstAllocation {{ .. }}")
     }
 }
 
-impl<'tcx, Prov, Extra> ConstAllocation<'tcx, Prov, Extra> {
-    pub fn inner(self) -> &'tcx Allocation<Prov, Extra> {
+impl<'tcx> ConstAllocation<'tcx> {
+    pub fn inner(self) -> &'tcx Allocation {
         self.0.0
     }
 }
@@ -183,12 +189,21 @@ pub fn alloc_range(start: Size, size: Size) -> AllocRange {
     AllocRange { start, size }
 }
 
-impl AllocRange {
+impl From<Range<Size>> for AllocRange {
     #[inline]
-    pub fn from(r: Range<Size>) -> Self {
+    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.
@@ -205,7 +220,7 @@ impl AllocRange {
 }
 
 // The constructors are all without extra; the extra gets added by a machine hook later.
-impl<Prov> Allocation<Prov> {
+impl<Prov: Provenance> Allocation<Prov> {
     /// Creates an allocation initialized by the given bytes
     pub fn from_bytes<'a>(
         slice: impl Into<Cow<'a, [u8]>>,
@@ -263,7 +278,7 @@ impl<Prov> Allocation<Prov> {
 impl Allocation {
     /// Adjust allocation from the ones in tcx to a custom Machine instance
     /// with a different Provenance and Extra type.
-    pub fn adjust_from_tcx<Prov, Extra, Err>(
+    pub fn adjust_from_tcx<Prov: Provenance, Extra, Err>(
         self,
         cx: &impl HasDataLayout,
         extra: Extra,
@@ -271,10 +286,10 @@ impl Allocation {
     ) -> Result<Allocation<Prov, Extra>, Err> {
         // Compute new pointer provenance, which also adjusts the bytes.
         let mut bytes = self.bytes;
-        let mut new_provenance = Vec::with_capacity(self.provenance.0.len());
+        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.iter() {
+        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();
@@ -286,7 +301,7 @@ impl Allocation {
         // Create allocation.
         Ok(Allocation {
             bytes,
-            provenance: ProvenanceMap::from_presorted(new_provenance),
+            provenance: ProvenanceMap::from_presorted_ptrs(new_provenance),
             init_mask: self.init_mask,
             align: self.align,
             mutability: self.mutability,
@@ -296,7 +311,7 @@ impl Allocation {
 }
 
 /// Raw accessors. Provide access to otherwise private bytes.
-impl<Prov, Extra> Allocation<Prov, Extra> {
+impl<Prov: Provenance, Extra> Allocation<Prov, Extra> {
     pub fn len(&self) -> usize {
         self.bytes.len()
     }
@@ -349,9 +364,14 @@ impl<Prov: Provenance, Extra> Allocation<Prov, Extra> {
         cx: &impl HasDataLayout,
         range: AllocRange,
     ) -> AllocResult<&[u8]> {
-        self.check_init(range)?;
+        self.init_mask.is_range_initialized(range).map_err(|uninit_range| {
+            AllocError::InvalidUninitBytes(Some(UninitBytesAccess {
+                access: range,
+                uninit: uninit_range,
+            }))
+        })?;
         if !Prov::OFFSET_IS_ADDR {
-            if self.range_has_provenance(cx, range) {
+            if !self.provenance.range_empty(range, cx) {
                 return Err(AllocError::ReadPointerAsBytes);
             }
         }
@@ -370,7 +390,7 @@ impl<Prov: Provenance, Extra> Allocation<Prov, Extra> {
         range: AllocRange,
     ) -> AllocResult<&mut [u8]> {
         self.mark_init(range, true);
-        self.clear_provenance(cx, range)?;
+        self.provenance.clear(range, cx)?;
 
         Ok(&mut self.bytes[range.start.bytes_usize()..range.end().bytes_usize()])
     }
@@ -382,7 +402,7 @@ impl<Prov: Provenance, Extra> Allocation<Prov, Extra> {
         range: AllocRange,
     ) -> AllocResult<*mut [u8]> {
         self.mark_init(range, true);
-        self.clear_provenance(cx, range)?;
+        self.provenance.clear(range, cx)?;
 
         assert!(range.end().bytes_usize() <= self.bytes.len()); // need to do our own bounds-check
         let begin_ptr = self.bytes.as_mut_ptr().wrapping_add(range.start.bytes_usize());
@@ -393,6 +413,15 @@ impl<Prov: Provenance, Extra> Allocation<Prov, Extra> {
 
 /// Reading and writing.
 impl<Prov: Provenance, Extra> Allocation<Prov, Extra> {
+    /// 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
@@ -410,7 +439,7 @@ impl<Prov: Provenance, Extra> Allocation<Prov, Extra> {
         read_provenance: bool,
     ) -> AllocResult<Scalar<Prov>> {
         // First and foremost, if anything is uninit, bail.
-        if self.is_init(range).is_err() {
+        if self.init_mask.is_range_initialized(range).is_err() {
             return Err(AllocError::InvalidUninitBytes(None));
         }
 
@@ -423,7 +452,7 @@ impl<Prov: Provenance, Extra> Allocation<Prov, Extra> {
 
             // 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(&range.start) {
+            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));
@@ -431,10 +460,9 @@ impl<Prov: Provenance, Extra> Allocation<Prov, Extra> {
 
             // If we can work on pointers byte-wise, join the byte-wise provenances.
             if Prov::OFFSET_IS_ADDR {
-                let mut prov = self.offset_get_provenance(cx, range.start);
-                for offset in 1..range.size.bytes() {
-                    let this_prov =
-                        self.offset_get_provenance(cx, range.start + Size::from_bytes(offset));
+                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.
@@ -452,7 +480,7 @@ impl<Prov: Provenance, Extra> Allocation<Prov, Extra> {
 
         // Fallback path for when we cannot treat provenance bytewise or ignore it.
         assert!(!Prov::OFFSET_IS_ADDR);
-        if self.range_has_provenance(cx, range) {
+        if !self.provenance.range_empty(range, cx) {
             return Err(AllocError::ReadPointerAsBytes);
         }
         // There is no provenance, we can just return the bits.
@@ -466,7 +494,6 @@ impl<Prov: Provenance, Extra> Allocation<Prov, Extra> {
     ///
     /// 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.
-    #[instrument(skip(self, cx), level = "debug")]
     pub fn write_scalar(
         &mut self,
         cx: &impl HasDataLayout,
@@ -478,11 +505,11 @@ impl<Prov: Provenance, Extra> Allocation<Prov, Extra> {
         // `to_bits_or_ptr_internal` is the right method because we just want to store this data
         // as-is into memory.
         let (bytes, provenance) = match val.to_bits_or_ptr_internal(range.size)? {
-            Err(val) => {
-                let (provenance, offset) = val.into_parts();
+            Right(ptr) => {
+                let (provenance, offset) = ptr.into_parts();
                 (u128::from(offset.bytes()), Some(provenance))
             }
-            Ok(data) => (data, None),
+            Left(data) => (data, None),
         };
 
         let endian = cx.data_layout().endian;
@@ -491,7 +518,8 @@ impl<Prov: Provenance, Extra> Allocation<Prov, Extra> {
 
         // See if we have to also store some provenance.
         if let Some(provenance) = provenance {
-            self.provenance.0.insert(range.start, provenance);
+            assert_eq!(range.size, cx.data_layout().pointer_size);
+            self.provenance.insert_ptr(range.start, provenance, cx);
         }
 
         Ok(())
@@ -500,750 +528,25 @@ impl<Prov: Provenance, Extra> Allocation<Prov, Extra> {
     /// 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.clear_provenance(cx, range)?;
+        self.provenance.clear(range, cx)?;
         return Ok(());
     }
-}
-
-/// Provenance.
-impl<Prov: Copy, Extra> Allocation<Prov, Extra> {
-    /// Returns all provenance overlapping with the given pointer-offset pair.
-    fn range_get_provenance(&self, cx: &impl HasDataLayout, range: AllocRange) -> &[(Size, Prov)] {
-        // We have to go back `pointer_size - 1` bytes, as that one would still overlap with
-        // the beginning of this range.
-        let start = range.start.bytes().saturating_sub(cx.data_layout().pointer_size.bytes() - 1);
-        self.provenance.range(Size::from_bytes(start)..range.end())
-    }
-
-    /// Get the provenance of a single byte.
-    fn offset_get_provenance(&self, cx: &impl HasDataLayout, offset: Size) -> Option<Prov> {
-        let prov = self.range_get_provenance(cx, alloc_range(offset, Size::from_bytes(1)));
-        assert!(prov.len() <= 1);
-        prov.first().map(|(_offset, prov)| *prov)
-    }
-
-    /// Returns whether this allocation has progrnance overlapping with the given range.
-    ///
-    /// Note: this function exists to allow `range_get_provenance` to be private, in order to somewhat
-    /// limit access to provenance outside of the `Allocation` abstraction.
-    ///
-    pub fn range_has_provenance(&self, cx: &impl HasDataLayout, range: AllocRange) -> bool {
-        !self.range_get_provenance(cx, range).is_empty()
-    }
-
-    /// Removes all provenance inside the given range.
-    /// If there is provenance overlapping with the edges, it
-    /// 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 clear_provenance(&mut self, cx: &impl HasDataLayout, range: AllocRange) -> AllocResult
-    where
-        Prov: Provenance,
-    {
-        // Find the start and end of the given range and its outermost provenance.
-        let (first, last) = {
-            // Find all provenance overlapping the given range.
-            let provenance = self.range_get_provenance(cx, range);
-            if provenance.is_empty() {
-                return Ok(());
-            }
-
-            (
-                provenance.first().unwrap().0,
-                provenance.last().unwrap().0 + cx.data_layout().pointer_size,
-            )
-        };
-        let start = range.start;
-        let end = range.end();
-
-        // We need to handle clearing the provenance from parts of a pointer.
-        // FIXME: Miri should preserve partial provenance; see
-        // https://github.com/rust-lang/miri/issues/2181.
-        if first < start {
-            if Prov::ERR_ON_PARTIAL_PTR_OVERWRITE {
-                return Err(AllocError::PartialPointerOverwrite(first));
-            }
-            warn!(
-                "Partial pointer overwrite! De-initializing memory at offsets {first:?}..{start:?}."
-            );
-            self.init_mask.set_range(first, start, false);
-        }
-        if last > end {
-            if Prov::ERR_ON_PARTIAL_PTR_OVERWRITE {
-                return Err(AllocError::PartialPointerOverwrite(
-                    last - cx.data_layout().pointer_size,
-                ));
-            }
-            warn!(
-                "Partial pointer overwrite! De-initializing memory at offsets {end:?}..{last:?}."
-            );
-            self.init_mask.set_range(end, last, false);
-        }
-
-        // Forget all the provenance.
-        // Since provenance do not overlap, we know that removing until `last` (exclusive) is fine,
-        // i.e., this will not remove any other provenance just after the ones we care about.
-        self.provenance.0.remove_range(first..last);
-
-        Ok(())
-    }
-}
-
-/// Stores the provenance information of pointers stored in memory.
-#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
-pub struct ProvenanceMap<Prov = AllocId>(SortedMap<Size, Prov>);
-
-impl<Prov> ProvenanceMap<Prov> {
-    pub fn new() -> Self {
-        ProvenanceMap(SortedMap::new())
-    }
-
-    // The caller must guarantee that the given provenance list is already sorted
-    // by address and contain no duplicates.
-    pub fn from_presorted(r: Vec<(Size, Prov)>) -> Self {
-        ProvenanceMap(SortedMap::from_presorted_elements(r))
-    }
-}
-
-impl<Prov> Deref for ProvenanceMap<Prov> {
-    type Target = SortedMap<Size, Prov>;
-
-    fn deref(&self) -> &Self::Target {
-        &self.0
-    }
-}
-
-/// A partial, owned list of provenance to transfer into another allocation.
-///
-/// Offsets are already adjusted to the destination allocation.
-pub struct AllocationProvenance<Prov> {
-    dest_provenance: Vec<(Size, Prov)>,
-}
-
-impl<Prov: Copy, Extra> Allocation<Prov, Extra> {
-    pub fn prepare_provenance_copy(
-        &self,
-        cx: &impl HasDataLayout,
-        src: AllocRange,
-        dest: Size,
-        count: u64,
-    ) -> AllocationProvenance<Prov> {
-        let provenance = self.range_get_provenance(cx, src);
-        if provenance.is_empty() {
-            return AllocationProvenance { dest_provenance: Vec::new() };
-        }
-
-        let size = src.size;
-        let mut new_provenance = Vec::with_capacity(provenance.len() * (count as usize));
-
-        // If `count` is large, this is rather wasteful -- we are allocating a big array here, which
-        // is mostly filled with redundant information since it's just N copies of the same `Prov`s
-        // at slightly adjusted offsets. The reason we do this is so that in `mark_provenance_range`
-        // we can use `insert_presorted`. That wouldn't work with an `Iterator` that just produces
-        // the right sequence of provenance for all N copies.
-        for i in 0..count {
-            new_provenance.extend(provenance.iter().map(|&(offset, reloc)| {
-                // compute offset for current repetition
-                let dest_offset = dest + size * i; // `Size` operations
-                (
-                    // shift offsets from source allocation to destination allocation
-                    (offset + dest_offset) - src.start, // `Size` operations
-                    reloc,
-                )
-            }));
-        }
-
-        AllocationProvenance { dest_provenance: new_provenance }
-    }
 
-    /// Applies a provenance copy.
-    /// The affected range, as defined in the parameters to `prepare_provenance_copy` is expected
+    /// 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 mark_provenance_range(&mut self, provenance: AllocationProvenance<Prov>) {
-        self.provenance.0.insert_presorted(provenance.dest_provenance);
-    }
-}
-
-////////////////////////////////////////////////////////////////////////////////
-// Uninitialized byte tracking
-////////////////////////////////////////////////////////////////////////////////
-
-type Block = u64;
-
-/// A bitmask where each bit refers to the byte with the same index. If the bit is `true`, the byte
-/// is initialized. If it is `false` the byte is uninitialized.
-// Note: for performance reasons when interning, some of the `InitMask` fields can be partially
-// hashed. (see the `Hash` impl below for more details), so the impl is not derived.
-#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable)]
-#[derive(HashStable)]
-pub struct InitMask {
-    blocks: Vec<Block>,
-    len: Size,
-}
-
-// 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 allocation's init mask. We can partially hash some fields when they're
-// large.
-impl hash::Hash for InitMask {
-    fn hash<H: hash::Hasher>(&self, state: &mut H) {
-        const MAX_BLOCKS_TO_HASH: usize = MAX_BYTES_TO_HASH / std::mem::size_of::<Block>();
-        const MAX_BLOCKS_LEN: usize = MAX_HASHED_BUFFER_LEN / std::mem::size_of::<Block>();
-
-        // Partially hash the `blocks` buffer when it is large. To limit collisions with common
-        // prefixes and suffixes, we hash the length and some slices of the buffer.
-        let block_count = self.blocks.len();
-        if block_count > MAX_BLOCKS_LEN {
-            // Hash the buffer's length.
-            block_count.hash(state);
-
-            // And its head and tail.
-            self.blocks[..MAX_BLOCKS_TO_HASH].hash(state);
-            self.blocks[block_count - MAX_BLOCKS_TO_HASH..].hash(state);
-        } else {
-            self.blocks.hash(state);
-        }
-
-        // Hash the other fields as usual.
-        self.len.hash(state);
-    }
-}
-
-impl InitMask {
-    pub const BLOCK_SIZE: u64 = 64;
-
-    #[inline]
-    fn bit_index(bits: Size) -> (usize, usize) {
-        // BLOCK_SIZE is the number of bits that can fit in a `Block`.
-        // Each bit in a `Block` represents the initialization state of one byte of an allocation,
-        // so we use `.bytes()` here.
-        let bits = bits.bytes();
-        let a = bits / InitMask::BLOCK_SIZE;
-        let b = bits % InitMask::BLOCK_SIZE;
-        (usize::try_from(a).unwrap(), usize::try_from(b).unwrap())
-    }
-
-    #[inline]
-    fn size_from_bit_index(block: impl TryInto<u64>, bit: impl TryInto<u64>) -> Size {
-        let block = block.try_into().ok().unwrap();
-        let bit = bit.try_into().ok().unwrap();
-        Size::from_bytes(block * InitMask::BLOCK_SIZE + bit)
-    }
-
-    pub fn new(size: Size, state: bool) -> Self {
-        let mut m = InitMask { blocks: vec![], len: Size::ZERO };
-        m.grow(size, state);
-        m
-    }
-
-    pub fn set_range(&mut self, start: Size, end: Size, new_state: bool) {
-        let len = self.len;
-        if end > len {
-            self.grow(end - len, new_state);
-        }
-        self.set_range_inbounds(start, end, new_state);
-    }
-
-    pub fn set_range_inbounds(&mut self, start: Size, end: Size, new_state: bool) {
-        let (blocka, bita) = Self::bit_index(start);
-        let (blockb, bitb) = Self::bit_index(end);
-        if blocka == blockb {
-            // First set all bits except the first `bita`,
-            // then unset the last `64 - bitb` bits.
-            let range = if bitb == 0 {
-                u64::MAX << bita
-            } else {
-                (u64::MAX << bita) & (u64::MAX >> (64 - bitb))
-            };
-            if new_state {
-                self.blocks[blocka] |= range;
-            } else {
-                self.blocks[blocka] &= !range;
-            }
-            return;
-        }
-        // across block boundaries
-        if new_state {
-            // Set `bita..64` to `1`.
-            self.blocks[blocka] |= u64::MAX << bita;
-            // Set `0..bitb` to `1`.
-            if bitb != 0 {
-                self.blocks[blockb] |= u64::MAX >> (64 - bitb);
-            }
-            // Fill in all the other blocks (much faster than one bit at a time).
-            for block in (blocka + 1)..blockb {
-                self.blocks[block] = u64::MAX;
-            }
-        } else {
-            // Set `bita..64` to `0`.
-            self.blocks[blocka] &= !(u64::MAX << bita);
-            // Set `0..bitb` to `0`.
-            if bitb != 0 {
-                self.blocks[blockb] &= !(u64::MAX >> (64 - bitb));
-            }
-            // Fill in all the other blocks (much faster than one bit at a time).
-            for block in (blocka + 1)..blockb {
-                self.blocks[block] = 0;
-            }
-        }
-    }
-
-    #[inline]
-    pub fn get(&self, i: Size) -> bool {
-        let (block, bit) = Self::bit_index(i);
-        (self.blocks[block] & (1 << bit)) != 0
+    pub fn provenance_apply_copy(&mut self, copy: ProvenanceCopy<Prov>) {
+        self.provenance.apply_copy(copy)
     }
 
-    #[inline]
-    pub fn set(&mut self, i: Size, new_state: bool) {
-        let (block, bit) = Self::bit_index(i);
-        self.set_bit(block, bit, new_state);
-    }
-
-    #[inline]
-    fn set_bit(&mut self, block: usize, bit: usize, new_state: bool) {
-        if new_state {
-            self.blocks[block] |= 1 << bit;
-        } else {
-            self.blocks[block] &= !(1 << bit);
-        }
-    }
-
-    pub fn grow(&mut self, amount: Size, new_state: bool) {
-        if amount.bytes() == 0 {
-            return;
-        }
-        let unused_trailing_bits =
-            u64::try_from(self.blocks.len()).unwrap() * Self::BLOCK_SIZE - self.len.bytes();
-        if amount.bytes() > unused_trailing_bits {
-            let additional_blocks = amount.bytes() / Self::BLOCK_SIZE + 1;
-            self.blocks.extend(
-                // FIXME(oli-obk): optimize this by repeating `new_state as Block`.
-                iter::repeat(0).take(usize::try_from(additional_blocks).unwrap()),
-            );
-        }
-        let start = self.len;
-        self.len += amount;
-        self.set_range_inbounds(start, start + amount, new_state); // `Size` operation
-    }
-
-    /// Returns the index of the first bit in `start..end` (end-exclusive) that is equal to is_init.
-    fn find_bit(&self, start: Size, end: Size, is_init: bool) -> Option<Size> {
-        /// A fast implementation of `find_bit`,
-        /// which skips over an entire block at a time if it's all 0s (resp. 1s),
-        /// and finds the first 1 (resp. 0) bit inside a block using `trailing_zeros` instead of a loop.
-        ///
-        /// Note that all examples below are written with 8 (instead of 64) bit blocks for simplicity,
-        /// and with the least significant bit (and lowest block) first:
-        /// ```text
-        ///        00000000|00000000
-        ///        ^      ^ ^      ^
-        /// index: 0      7 8      15
-        /// ```
-        /// Also, if not stated, assume that `is_init = true`, that is, we are searching for the first 1 bit.
-        fn find_bit_fast(
-            init_mask: &InitMask,
-            start: Size,
-            end: Size,
-            is_init: bool,
-        ) -> Option<Size> {
-            /// Search one block, returning the index of the first bit equal to `is_init`.
-            fn search_block(
-                bits: Block,
-                block: usize,
-                start_bit: usize,
-                is_init: bool,
-            ) -> Option<Size> {
-                // For the following examples, assume this function was called with:
-                //   bits = 0b00111011
-                //   start_bit = 3
-                //   is_init = false
-                // Note that, for the examples in this function, the most significant bit is written first,
-                // which is backwards compared to the comments in `find_bit`/`find_bit_fast`.
-
-                // Invert bits so we're always looking for the first set bit.
-                //        ! 0b00111011
-                //   bits = 0b11000100
-                let bits = if is_init { bits } else { !bits };
-                // Mask off unused start bits.
-                //          0b11000100
-                //        & 0b11111000
-                //   bits = 0b11000000
-                let bits = bits & (!0 << start_bit);
-                // Find set bit, if any.
-                //   bit = trailing_zeros(0b11000000)
-                //   bit = 6
-                if bits == 0 {
-                    None
-                } else {
-                    let bit = bits.trailing_zeros();
-                    Some(InitMask::size_from_bit_index(block, bit))
-                }
-            }
-
-            if start >= end {
-                return None;
-            }
-
-            // Convert `start` and `end` to block indexes and bit indexes within each block.
-            // We must convert `end` to an inclusive bound to handle block boundaries correctly.
-            //
-            // For example:
-            //
-            //   (a) 00000000|00000000    (b) 00000000|
-            //       ^~~~~~~~~~~^             ^~~~~~~~~^
-            //     start       end          start     end
-            //
-            // In both cases, the block index of `end` is 1.
-            // But we do want to search block 1 in (a), and we don't in (b).
-            //
-            // We subtract 1 from both end positions to make them inclusive:
-            //
-            //   (a) 00000000|00000000    (b) 00000000|
-            //       ^~~~~~~~~~^              ^~~~~~~^
-            //     start    end_inclusive   start end_inclusive
-            //
-            // For (a), the block index of `end_inclusive` is 1, and for (b), it's 0.
-            // This provides the desired behavior of searching blocks 0 and 1 for (a),
-            // and searching only block 0 for (b).
-            // There is no concern of overflows since we checked for `start >= end` above.
-            let (start_block, start_bit) = InitMask::bit_index(start);
-            let end_inclusive = Size::from_bytes(end.bytes() - 1);
-            let (end_block_inclusive, _) = InitMask::bit_index(end_inclusive);
-
-            // Handle first block: need to skip `start_bit` bits.
-            //
-            // We need to handle the first block separately,
-            // because there may be bits earlier in the block that should be ignored,
-            // such as the bit marked (1) in this example:
-            //
-            //       (1)
-            //       -|------
-            //   (c) 01000000|00000000|00000001
-            //          ^~~~~~~~~~~~~~~~~~^
-            //        start              end
-            if let Some(i) =
-                search_block(init_mask.blocks[start_block], start_block, start_bit, is_init)
-            {
-                // If the range is less than a block, we may find a matching bit after `end`.
-                //
-                // For example, we shouldn't successfully find bit (2), because it's after `end`:
-                //
-                //             (2)
-                //       -------|
-                //   (d) 00000001|00000000|00000001
-                //        ^~~~~^
-                //      start end
-                //
-                // An alternative would be to mask off end bits in the same way as we do for start bits,
-                // but performing this check afterwards is faster and simpler to implement.
-                if i < end {
-                    return Some(i);
-                } else {
-                    return None;
-                }
-            }
-
-            // Handle remaining blocks.
-            //
-            // We can skip over an entire block at once if it's all 0s (resp. 1s).
-            // The block marked (3) in this example is the first block that will be handled by this loop,
-            // and it will be skipped for that reason:
-            //
-            //                   (3)
-            //                --------
-            //   (e) 01000000|00000000|00000001
-            //          ^~~~~~~~~~~~~~~~~~^
-            //        start              end
-            if start_block < end_block_inclusive {
-                // This loop is written in a specific way for performance.
-                // Notably: `..end_block_inclusive + 1` is used for an inclusive range instead of `..=end_block_inclusive`,
-                // and `.zip(start_block + 1..)` is used to track the index instead of `.enumerate().skip().take()`,
-                // because both alternatives result in significantly worse codegen.
-                // `end_block_inclusive + 1` is guaranteed not to wrap, because `end_block_inclusive <= end / BLOCK_SIZE`,
-                // and `BLOCK_SIZE` (the number of bits per block) will always be at least 8 (1 byte).
-                for (&bits, block) in init_mask.blocks[start_block + 1..end_block_inclusive + 1]
-                    .iter()
-                    .zip(start_block + 1..)
-                {
-                    if let Some(i) = search_block(bits, block, 0, is_init) {
-                        // If this is the last block, we may find a matching bit after `end`.
-                        //
-                        // For example, we shouldn't successfully find bit (4), because it's after `end`:
-                        //
-                        //                               (4)
-                        //                         -------|
-                        //   (f) 00000001|00000000|00000001
-                        //          ^~~~~~~~~~~~~~~~~~^
-                        //        start              end
-                        //
-                        // As above with example (d), we could handle the end block separately and mask off end bits,
-                        // but unconditionally searching an entire block at once and performing this check afterwards
-                        // is faster and much simpler to implement.
-                        if i < end {
-                            return Some(i);
-                        } else {
-                            return None;
-                        }
-                    }
-                }
-            }
-
-            None
-        }
-
-        #[cfg_attr(not(debug_assertions), allow(dead_code))]
-        fn find_bit_slow(
-            init_mask: &InitMask,
-            start: Size,
-            end: Size,
-            is_init: bool,
-        ) -> Option<Size> {
-            (start..end).find(|&i| init_mask.get(i) == is_init)
-        }
-
-        let result = find_bit_fast(self, start, end, is_init);
-
-        debug_assert_eq!(
-            result,
-            find_bit_slow(self, start, end, is_init),
-            "optimized implementation of find_bit is wrong for start={:?} end={:?} is_init={} init_mask={:#?}",
-            start,
-            end,
-            is_init,
-            self
-        );
-
-        result
-    }
-}
-
-/// A contiguous chunk of initialized or uninitialized memory.
-pub enum InitChunk {
-    Init(Range<Size>),
-    Uninit(Range<Size>),
-}
-
-impl InitChunk {
-    #[inline]
-    pub fn is_init(&self) -> bool {
-        match self {
-            Self::Init(_) => true,
-            Self::Uninit(_) => false,
-        }
-    }
-
-    #[inline]
-    pub fn range(&self) -> Range<Size> {
-        match self {
-            Self::Init(r) => r.clone(),
-            Self::Uninit(r) => r.clone(),
-        }
-    }
-}
-
-impl InitMask {
-    /// Checks whether the range `start..end` (end-exclusive) is entirely initialized.
-    ///
-    /// Returns `Ok(())` if it's initialized. Otherwise returns a range of byte
-    /// indexes for the first contiguous span of the uninitialized access.
-    #[inline]
-    pub fn is_range_initialized(&self, start: Size, end: Size) -> Result<(), AllocRange> {
-        if end > self.len {
-            return Err(AllocRange::from(self.len..end));
-        }
-
-        let uninit_start = self.find_bit(start, end, false);
-
-        match uninit_start {
-            Some(uninit_start) => {
-                let uninit_end = self.find_bit(uninit_start, end, true).unwrap_or(end);
-                Err(AllocRange::from(uninit_start..uninit_end))
-            }
-            None => Ok(()),
-        }
-    }
-
-    /// Returns an iterator, yielding a range of byte indexes for each contiguous region
-    /// of initialized or uninitialized bytes inside the range `start..end` (end-exclusive).
-    ///
-    /// The iterator guarantees the following:
-    /// - Chunks are nonempty.
-    /// - Chunks are adjacent (each range's start is equal to the previous range's end).
-    /// - Chunks span exactly `start..end` (the first starts at `start`, the last ends at `end`).
-    /// - Chunks alternate between [`InitChunk::Init`] and [`InitChunk::Uninit`].
-    #[inline]
-    pub fn range_as_init_chunks(&self, start: Size, end: Size) -> InitChunkIter<'_> {
-        assert!(end <= self.len);
-
-        let is_init = if start < end {
-            self.get(start)
-        } else {
-            // `start..end` is empty: there are no chunks, so use some arbitrary value
-            false
-        };
-
-        InitChunkIter { init_mask: self, is_init, start, end }
-    }
-}
-
-/// Yields [`InitChunk`]s. See [`InitMask::range_as_init_chunks`].
-#[derive(Clone)]
-pub struct InitChunkIter<'a> {
-    init_mask: &'a InitMask,
-    /// Whether the next chunk we will return is initialized.
-    /// If there are no more chunks, contains some arbitrary value.
-    is_init: bool,
-    /// The current byte index into `init_mask`.
-    start: Size,
-    /// The end byte index into `init_mask`.
-    end: Size,
-}
-
-impl<'a> Iterator for InitChunkIter<'a> {
-    type Item = InitChunk;
-
-    #[inline]
-    fn next(&mut self) -> Option<Self::Item> {
-        if self.start >= self.end {
-            return None;
-        }
-
-        let end_of_chunk =
-            self.init_mask.find_bit(self.start, self.end, !self.is_init).unwrap_or(self.end);
-        let range = self.start..end_of_chunk;
-
-        let ret =
-            Some(if self.is_init { InitChunk::Init(range) } else { InitChunk::Uninit(range) });
-
-        self.is_init = !self.is_init;
-        self.start = end_of_chunk;
-
-        ret
-    }
-}
-
-/// Uninitialized bytes.
-impl<Prov: Copy, Extra> Allocation<Prov, Extra> {
-    /// 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 is_init(&self, range: AllocRange) -> Result<(), AllocRange> {
-        self.init_mask.is_range_initialized(range.start, range.end()) // `Size` addition
-    }
-
-    /// 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.
-    fn check_init(&self, range: AllocRange) -> AllocResult {
-        self.is_init(range).map_err(|uninit_range| {
-            AllocError::InvalidUninitBytes(Some(UninitBytesAccess {
-                access: range,
-                uninit: uninit_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.start, range.end(), is_init);
-    }
-}
-
-/// Run-length encoding of the uninit mask.
-/// Used to copy parts of a mask multiple times to another allocation.
-pub struct InitMaskCompressed {
-    /// Whether the first range is initialized.
-    initial: bool,
-    /// The lengths of ranges that are run-length encoded.
-    /// The initialization state of the ranges alternate starting with `initial`.
-    ranges: smallvec::SmallVec<[u64; 1]>,
-}
-
-impl InitMaskCompressed {
-    pub fn no_bytes_init(&self) -> bool {
-        // The `ranges` are run-length encoded and of alternating initialization state.
-        // So if `ranges.len() > 1` then the second block is an initialized range.
-        !self.initial && self.ranges.len() == 1
-    }
-}
-
-/// Transferring the initialization mask to other allocations.
-impl<Prov, Extra> Allocation<Prov, Extra> {
-    /// 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 compress_uninit_range(&self, range: AllocRange) -> InitMaskCompressed {
-        // Since we are copying `size` bytes from `src` to `dest + i * size` (`for i in 0..repeat`),
-        // a naive initialization mask copying algorithm would repeatedly have to read the initialization mask from
-        // the source and write it to the destination. Even if we optimized the memory accesses,
-        // we'd be doing all of this `repeat` times.
-        // Therefore we precompute a compressed version of the initialization mask of the source value and
-        // then write it back `repeat` times without computing any more information from the source.
-
-        // A precomputed cache for ranges of initialized / uninitialized bits
-        // 0000010010001110 will become
-        // `[5, 1, 2, 1, 3, 3, 1]`,
-        // where each element toggles the state.
-
-        let mut ranges = smallvec::SmallVec::<[u64; 1]>::new();
-
-        let mut chunks = self.init_mask.range_as_init_chunks(range.start, range.end()).peekable();
-
-        let initial = chunks.peek().expect("range should be nonempty").is_init();
-
-        // Here we rely on `range_as_init_chunks` to yield alternating init/uninit chunks.
-        for chunk in chunks {
-            let len = chunk.range().end.bytes() - chunk.range().start.bytes();
-            ranges.push(len);
-        }
-
-        InitMaskCompressed { ranges, initial }
-    }
-
-    /// Applies multiple instances of the run-length encoding to the initialization mask.
+    /// 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 mark_compressed_init_range(
-        &mut self,
-        defined: &InitMaskCompressed,
-        range: AllocRange,
-        repeat: u64,
-    ) {
-        // An optimization where we can just overwrite an entire range of initialization
-        // bits if they are going to be uniformly `1` or `0`.
-        if defined.ranges.len() <= 1 {
-            self.init_mask.set_range_inbounds(
-                range.start,
-                range.start + range.size * repeat, // `Size` operations
-                defined.initial,
-            );
-            return;
-        }
-
-        for mut j in 0..repeat {
-            j *= range.size.bytes();
-            j += range.start.bytes();
-            let mut cur = defined.initial;
-            for range in &defined.ranges {
-                let old_j = j;
-                j += range;
-                self.init_mask.set_range_inbounds(
-                    Size::from_bytes(old_j),
-                    Size::from_bytes(j),
-                    cur,
-                );
-                cur = !cur;
-            }
-        }
+    pub fn init_mask_apply_copy(&mut self, copy: InitCopy, range: AllocRange, repeat: u64) {
+        self.init_mask.apply_copy(copy, range, repeat)
     }
 }