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Replace rust-timsort with an in-tree powersort #8421

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Merged
youknowone merged 7 commits into from
Aug 2, 2026
Merged

Replace rust-timsort with an in-tree powersort #8421

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6e1c04e
Add powersort implementation for list sorting
kangdora Jul 31, 2026
5b52036
Use powersort for list.sort() and drop rust-timsort
kangdora Jul 31, 2026
e5a5247
Fix usize underflow in merge_hi Succeed path
kangdora Jul 31, 2026
189e6e7
Fix clippy warnings and formatting in sorting.rs
kangdora Jul 31, 2026
526820b
Drop redundant test_ prefixes in sorting tests
kangdora Aug 1, 2026
ecbda8e
Restore buffered elements when a comparison fails mid-merge
kangdora Aug 1, 2026
b4fda72
Copy one run-A element per gallop round in merge_lo
kangdora Aug 1, 2026
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Use powersort for list.sort() and drop rust-timsort 
Wire list sorting through crate::sorting::timsort and remove the
rust-timsort dependency. Fixes the O(N^2) behavior on random input
(1M random floats: ~16min -> ~0.8s), now within ~4x of CPython.
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@kangdora
kangdora committed Jul 31, 2026
commit 5b52036263f9d6a5b9b6c22d01216ecd5eb4b732
7 changes: 0 additions & 7 deletions Cargo.lock
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1 change: 0 additions & 1 deletion Cargo.toml
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Expand Up @@ -305,7 +305,6 @@ textwrap = { version = "0.16.2", default-features = false }
termios = "0.3.3"
thiserror = "2.0"
thin-vec = "0.2.14"
timsort = "0.1.2"
tk-sys = { git = "https://github.com/arihant2math/tkinter.git", tag = "v0.2.0" }
icu_casemap = "2"
icu_locale = "2"
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1 change: 0 additions & 1 deletion crates/vm/Cargo.toml
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Expand Up @@ -80,7 +80,6 @@ half = { workspace = true }
psm = { workspace = true }
optional = { workspace = true }
result-like = { workspace = true }
timsort = { workspace = true }

[target.'cfg(unix)'.dependencies]
exitcode = { workspace = true }
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13 changes: 6 additions & 7 deletions crates/vm/src/builtins/list.rs
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Expand Up @@ -18,6 +18,7 @@ use crate::{
recursion::ReprGuard,
sequence::{MutObjectSequenceOp, OptionalRangeArgs, SequenceExt, SequenceMutExt},
sliceable::{SequenceIndex, SliceableSequenceMutOp, SliceableSequenceOp},
sorting::timsort,
types::{
AsMapping, AsSequence, Comparable, Constructor, Initializer, IterNext, Iterable,
PyComparisonOp, Representable, SelfIter,
Expand Down Expand Up @@ -642,13 +643,11 @@ fn do_sort(
) -> PyResult<()> {
// CPython uses __lt__ for all comparisons in sort.
// try_sort_by_gt expects is_gt(a, b) = true when a should come AFTER b.
let cmp = |a: &PyObjectRef, b: &PyObjectRef| {
let mut is_lt = |a: &PyObjectRef, b: &PyObjectRef| {
if reverse {
// Descending: a comes after b when a < b
a.rich_compare_bool(b, PyComparisonOp::Lt, vm)
} else {
// Ascending: a comes after b when b < a
b.rich_compare_bool(a, PyComparisonOp::Lt, vm)
} else {
a.rich_compare_bool(b, PyComparisonOp::Lt, vm)
}
};
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coderabbitai[bot] marked this conversation as resolved.

Expand All @@ -657,10 +656,10 @@ fn do_sort(
.iter()
.map(|x| Ok((x.clone(), key_func.call((x.clone(),), vm)?)))
.collect::<Result<Vec<_>, _>>()?;
timsort::try_sort_by_gt(&mut items, |a, b| cmp(&a.1, &b.1))?;
timsort(&mut items, &mut |a, b| is_lt(&a.1, &b.1))?;
*values = items.into_iter().map(|(val, _)| val).collect();
} else {
timsort::try_sort_by_gt(values, cmp)?;
timsort(values, &mut is_lt)?;
}

Ok(())
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