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another optimization attempt

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This commit is contained in:
Ralf Jung 2022-11-09 10:18:27 +01:00
parent f0e5545670
commit b04166ff35
1 changed files with 83 additions and 66 deletions
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149
compiler/rustc_middle/src/mir/interpret/allocation/provenance_map.rs
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@ -18,18 +18,18 @@ pub struct ProvenanceMap<Prov = AllocId> {
/// Provenance in this map only applies to the given single byte.
/// This map is disjoint from the previous. It will always be empty when
/// `Prov::OFFSET_IS_ADDR` is false.
bytes: SortedMap<Size, Prov>,
bytes: Option<Box<SortedMap<Size, Prov>>>,
}
impl<Prov> ProvenanceMap<Prov> {
pub fn new() -> Self {
ProvenanceMap { ptrs: SortedMap::new(), bytes: SortedMap::new() }
ProvenanceMap { ptrs: SortedMap::new(), bytes: None }
}
/// The caller must guarantee that the given provenance list is already sorted
/// by address and contain no duplicates.
pub fn from_presorted_ptrs(r: Vec<(Size, Prov)>) -> Self {
ProvenanceMap { ptrs: SortedMap::from_presorted_elements(r), bytes: SortedMap::new() }
ProvenanceMap { ptrs: SortedMap::from_presorted_elements(r), bytes: None }
}
}
@ -40,7 +40,7 @@ impl ProvenanceMap {
/// Only exposed with `AllocId` provenance, since it panics if there is bytewise provenance.
#[inline]
pub fn ptrs(&self) -> &SortedMap<Size, AllocId> {
debug_assert!(self.bytes.is_empty()); // `AllocId::OFFSET_IS_ADDR` is false so this cannot fail
debug_assert!(self.bytes.is_none()); // `AllocId::OFFSET_IS_ADDR` is false so this cannot fail
&self.ptrs
}
}
@ -60,7 +60,11 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
/// Returns all byte-wise provenance in the given range.
fn range_get_bytes(&self, range: AllocRange) -> &[(Size, Prov)] {
self.bytes.range(range.start..range.end())
if let Some(bytes) = self.bytes.as_ref() {
bytes.range(range.start..range.end())
} else {
&[]
}
}
/// Get the provenance of a single byte.
@ -69,11 +73,11 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
debug_assert!(prov.len() <= 1);
if let Some(entry) = prov.first() {
// If it overlaps with this byte, it is on this byte.
debug_assert!(self.bytes.get(&offset).is_none());
debug_assert!(self.bytes.as_ref().map_or(true, |b| b.get(&offset).is_none()));
Some(entry.1)
} else {
// Look up per-byte provenance.
self.bytes.get(&offset).copied()
self.bytes.as_ref().and_then(|b| b.get(&offset).copied())
}
}
@ -94,7 +98,8 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
/// Yields all the provenances stored in this map.
pub fn provenances(&self) -> impl Iterator<Item = Prov> + '_ {
self.ptrs.values().chain(self.bytes.values()).copied()
let bytes = self.bytes.iter().flat_map(|b| b.values());
self.ptrs.values().chain(bytes).copied()
}
pub fn insert_ptr(&mut self, offset: Size, prov: Prov, cx: &impl HasDataLayout) {
@ -109,9 +114,11 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
let end = range.end();
// Clear the bytewise part -- this is easy.
if Prov::OFFSET_IS_ADDR {
self.bytes.remove_range(start..end);
if let Some(bytes) = self.bytes.as_mut() {
bytes.remove_range(start..end);
}
} else {
debug_assert!(self.bytes.is_empty());
debug_assert!(self.bytes.is_none());
}
// For the ptr-sized part, find the first (inclusive) and last (exclusive) byte of
@ -138,8 +145,9 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
}
// Insert the remaining part in the bytewise provenance.
let prov = self.ptrs[&first];
let bytes = self.bytes.get_or_insert_with(Box::default);
for offset in first..start {
self.bytes.insert(offset, prov);
bytes.insert(offset, prov);
}
}
if last > end {
@ -150,8 +158,9 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
}
// Insert the remaining part in the bytewise provenance.
let prov = self.ptrs[&begin_of_last];
let bytes = self.bytes.get_or_insert_with(Box::default);
for offset in end..last {
self.bytes.insert(offset, prov);
bytes.insert(offset, prov);
}
}
@ -168,8 +177,8 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
///
/// Offsets are already adjusted to the destination allocation.
pub struct ProvenanceCopy<Prov> {
dest_ptrs: Vec<(Size, Prov)>,
dest_bytes: Vec<(Size, Prov)>,
dest_ptrs: Option<Box<[(Size, Prov)]>>,
dest_bytes: Option<Box<[(Size, Prov)]>>,
}
impl<Prov: Provenance> ProvenanceMap<Prov> {
@ -192,96 +201,104 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
// Get the provenances that are entirely within this range.
// (Different from `range_get_ptrs` which asks if they overlap the range.)
// Only makes sense if we are copying at least one pointer worth of bytes.
let mut dest_ptrs = Vec::new();
let mut dest_ptrs_box = None;
if src.size >= ptr_size {
let adjusted_end = Size::from_bytes(src.end().bytes() - (ptr_size.bytes() - 1));
let ptrs = self.ptrs.range(src.start..adjusted_end);
dest_ptrs.reserve_exact(ptrs.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.
// Basically, this large array would have to be created anyway in the target allocation.
let mut dest_ptrs = Vec::with_capacity(ptrs.len() * (count as usize));
for i in 0..count {
dest_ptrs
.extend(ptrs.iter().map(|&(offset, reloc)| (shift_offset(i, offset), reloc)));
}
debug_assert_eq!(dest_ptrs.len(), dest_ptrs.capacity());
dest_ptrs_box = Some(dest_ptrs.into_boxed_slice());
};
// # Byte-sized provenances
let mut bytes = Vec::new();
// First, if there is a part of a pointer at the start, add that.
if let Some(entry) = self.range_get_ptrs(alloc_range(src.start, Size::ZERO), cx).first() {
if !Prov::OFFSET_IS_ADDR {
// We can't split up the provenance into less than a pointer.
// This includes the existing bytewise provenance in the range, and ptr provenance
// that overlaps with the begin/end of the range.
let mut dest_bytes_box = None;
let begin_overlap = self.range_get_ptrs(alloc_range(src.start, Size::ZERO), cx).first();
let end_overlap = self.range_get_ptrs(alloc_range(src.end(), Size::ZERO), cx).first();
if !Prov::OFFSET_IS_ADDR {
// There can't be any bytewise provenance, and we cannot split up the begin/end overlap.
if let Some(entry) = begin_overlap {
return Err(AllocError::PartialPointerCopy(entry.0));
}
trace!("start overlapping entry: {entry:?}");
// For really small copies, make sure we don't run off the end of the `src` range.
let entry_end = cmp::min(entry.0 + ptr_size, src.end());
for offset in src.start..entry_end {
bytes.push((offset, entry.1));
}
} else {
trace!("no start overlapping entry");
}
// Then the main part, bytewise provenance from `self.bytes`.
if Prov::OFFSET_IS_ADDR {
bytes.extend(self.bytes.range(src.start..src.end()));
} else {
debug_assert!(self.bytes.is_empty());
}
// And finally possibly parts of a pointer at the end.
if let Some(entry) = self.range_get_ptrs(alloc_range(src.end(), Size::ZERO), cx).first() {
if !Prov::OFFSET_IS_ADDR {
// We can't split up the provenance into less than a pointer.
if let Some(entry) = end_overlap {
return Err(AllocError::PartialPointerCopy(entry.0));
}
trace!("end overlapping entry: {entry:?}");
// For really small copies, make sure we don't start before `src` does.
let entry_start = cmp::max(entry.0, src.start);
for offset in entry_start..src.end() {
if bytes.last().map_or(true, |bytes_entry| bytes_entry.0 < offset) {
// The last entry, if it exists, has a lower offset than us.
debug_assert!(self.bytes.is_none());
} else {
let mut bytes = Vec::new();
// First, if there is a part of a pointer at the start, add that.
if let Some(entry) = begin_overlap {
trace!("start overlapping entry: {entry:?}");
// For really small copies, make sure we don't run off the end of the `src` range.
let entry_end = cmp::min(entry.0 + ptr_size, src.end());
for offset in src.start..entry_end {
bytes.push((offset, entry.1));
} else {
// There already is an entry for this offset in there! This can happen when the
// start and end range checks actually end up hitting the same pointer, so we
// already added this in the "pointer at the start" part above.
assert!(entry.0 <= src.start);
}
} else {
trace!("no start overlapping entry");
}
} else {
trace!("no end overlapping entry");
}
trace!("byte provenances: {bytes:?}");
// Then the main part, bytewise provenance from `self.bytes`.
if let Some(all_bytes) = self.bytes.as_ref() {
bytes.extend(all_bytes.range(src.start..src.end()));
}
// And finally possibly parts of a pointer at the end.
if let Some(entry) = end_overlap {
trace!("end overlapping entry: {entry:?}");
// For really small copies, make sure we don't start before `src` does.
let entry_start = cmp::max(entry.0, src.start);
for offset in entry_start..src.end() {
if bytes.last().map_or(true, |bytes_entry| bytes_entry.0 < offset) {
// The last entry, if it exists, has a lower offset than us.
bytes.push((offset, entry.1));
} else {
// There already is an entry for this offset in there! This can happen when the
// start and end range checks actually end up hitting the same pointer, so we
// already added this in the "pointer at the start" part above.
assert!(entry.0 <= src.start);
}
}
} else {
trace!("no end overlapping entry");
}
trace!("byte provenances: {bytes:?}");
// And again a buffer for the new list on the target side.
let mut dest_bytes = Vec::new();
if Prov::OFFSET_IS_ADDR {
dest_bytes.reserve_exact(bytes.len() * (count as usize));
// And again a buffer for the new list on the target side.
let mut dest_bytes = Vec::with_capacity(bytes.len() * (count as usize));
for i in 0..count {
dest_bytes
.extend(bytes.iter().map(|&(offset, reloc)| (shift_offset(i, offset), reloc)));
}
} else {
// There can't be any bytewise provenance when OFFSET_IS_ADDR is false.
debug_assert!(bytes.is_empty());
debug_assert_eq!(dest_bytes.len(), dest_bytes.capacity());
dest_bytes_box = Some(dest_bytes.into_boxed_slice());
}
Ok(ProvenanceCopy { dest_ptrs, dest_bytes })
Ok(ProvenanceCopy { dest_ptrs: dest_ptrs_box, dest_bytes: dest_bytes_box })
}
/// Applies a provenance copy.
/// The affected range, as defined in the parameters to `prepare_copy` is expected
/// to be clear of provenance.
pub fn apply_copy(&mut self, copy: ProvenanceCopy<Prov>) {
self.ptrs.insert_presorted(copy.dest_ptrs);
if let Some(dest_ptrs) = copy.dest_ptrs {
self.ptrs.insert_presorted(dest_ptrs.into());
}
if Prov::OFFSET_IS_ADDR {
self.bytes.insert_presorted(copy.dest_bytes);
if let Some(dest_bytes) = copy.dest_bytes && !dest_bytes.is_empty() {
self.bytes.get_or_insert_with(Box::default).insert_presorted(dest_bytes.into());
}
} else {
debug_assert!(copy.dest_bytes.is_empty());
debug_assert!(copy.dest_bytes.is_none());
}
}
}