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Auto merge of #109458 - Nilstrieb:smol-cute-little-bits, r=wesleywiser

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Use `SmallVec` in bitsets

This doesn't increase their size and means that we don't have to heap allocate for small sets.
This commit is contained in:
bors 2023-03-25 17:06:43 +00:00
commit 2d429f3064
1 changed files with 7 additions and 5 deletions
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12
compiler/rustc_index/src/bit_set.rs
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@ -1,5 +1,6 @@
use crate::vec::{Idx, IndexVec};
use arrayvec::ArrayVec;
use smallvec::{smallvec, SmallVec};
use std::fmt;
use std::iter;
use std::marker::PhantomData;
@ -111,7 +112,7 @@ macro_rules! bit_relations_inherent_impls {
#[derive(Eq, PartialEq, Hash, Decodable, Encodable)]
pub struct BitSet<T> {
domain_size: usize,
words: Vec<Word>,
words: SmallVec<[Word; 2]>,
marker: PhantomData<T>,
}
@ -127,14 +128,15 @@ impl<T: Idx> BitSet<T> {
#[inline]
pub fn new_empty(domain_size: usize) -> BitSet<T> {
let num_words = num_words(domain_size);
BitSet { domain_size, words: vec![0; num_words], marker: PhantomData }
BitSet { domain_size, words: smallvec![0; num_words], marker: PhantomData }
}
/// Creates a new, filled bitset with a given `domain_size`.
#[inline]
pub fn new_filled(domain_size: usize) -> BitSet<T> {
let num_words = num_words(domain_size);
let mut result = BitSet { domain_size, words: vec![!0; num_words], marker: PhantomData };
let mut result =
BitSet { domain_size, words: smallvec![!0; num_words], marker: PhantomData };
result.clear_excess_bits();
result
}
@ -1571,7 +1573,7 @@ impl<T: Idx> From<BitSet<T>> for GrowableBitSet<T> {
pub struct BitMatrix<R: Idx, C: Idx> {
num_rows: usize,
num_columns: usize,
words: Vec<Word>,
words: SmallVec<[Word; 2]>,
marker: PhantomData<(R, C)>,
}
@ -1584,7 +1586,7 @@ impl<R: Idx, C: Idx> BitMatrix<R, C> {
BitMatrix {
num_rows,
num_columns,
words: vec![0; num_rows * words_per_row],
words: smallvec![0; num_rows * words_per_row],
marker: PhantomData,
}
}