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consolidate: fix a Miri error #394

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Merged
merged 1 commit into from
Jun 15, 2023
Merged

consolidate: fix a Miri error #394

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16 changes: 10 additions & 6 deletions src/consolidation.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,8 @@ pub fn consolidate_slice<T: Ord, R: Semigroup>(slice: &mut [(T, R)]) -> usize {
// In a world where there are not many results, we may never even need to call in to merge sort.
slice.sort_by(|x,y| x.0.cmp(&y.0));

let slice_ptr = slice.as_mut_ptr();

// Counts the number of distinct known-non-zero accumulations. Indexes the write location.
let mut offset = 0;
for index in 1 .. slice.len() {
Expand All @@ -55,8 +57,8 @@ pub fn consolidate_slice<T: Ord, R: Semigroup>(slice: &mut [(T, R)]) -> usize {
assert!(offset < index);

// LOOP INVARIANT: offset < index
let ptr1 = slice.as_mut_ptr().offset(offset as isize);
let ptr2 = slice.as_mut_ptr().offset(index as isize);
let ptr1 = slice_ptr.add(offset);
let ptr2 = slice_ptr.add(index);

if (*ptr1).0 == (*ptr2).0 {
(*ptr1).1.plus_equals(&(*ptr2).1);
Expand All @@ -65,7 +67,7 @@ pub fn consolidate_slice<T: Ord, R: Semigroup>(slice: &mut [(T, R)]) -> usize {
if !(*ptr1).1.is_zero() {
offset += 1;
}
let ptr1 = slice.as_mut_ptr().offset(offset as isize);
let ptr1 = slice_ptr.add(offset);
std::ptr::swap(ptr1, ptr2);
}
}
Expand Down Expand Up @@ -103,6 +105,8 @@ pub fn consolidate_updates_slice<D: Ord, T: Ord, R: Semigroup>(slice: &mut [(D,
// In a world where there are not many results, we may never even need to call in to merge sort.
slice.sort_unstable_by(|x,y| (&x.0, &x.1).cmp(&(&y.0, &y.1)));

let slice_ptr = slice.as_mut_ptr();

// Counts the number of distinct known-non-zero accumulations. Indexes the write location.
let mut offset = 0;
for index in 1 .. slice.len() {
Expand All @@ -118,8 +122,8 @@ pub fn consolidate_updates_slice<D: Ord, T: Ord, R: Semigroup>(slice: &mut [(D,
unsafe {

// LOOP INVARIANT: offset < index
let ptr1 = slice.as_mut_ptr().offset(offset as isize);
let ptr2 = slice.as_mut_ptr().offset(index as isize);
let ptr1 = slice_ptr.add(offset);
let ptr2 = slice_ptr.add(index);

if (*ptr1).0 == (*ptr2).0 && (*ptr1).1 == (*ptr2).1 {
(*ptr1).2.plus_equals(&(*ptr2).2);
Expand All @@ -128,7 +132,7 @@ pub fn consolidate_updates_slice<D: Ord, T: Ord, R: Semigroup>(slice: &mut [(D,
if !(*ptr1).2.is_zero() {
offset += 1;
}
let ptr1 = slice.as_mut_ptr().offset(offset as isize);
let ptr1 = slice_ptr.add(offset);
std::ptr::swap(ptr1, ptr2);
}

Expand Down