!! (WIP) switch to Box<[Word]>

Author: Zalathar

compiler/rustc_index/src/bit_set.rs

@@ -121,7 +121,7 @@ macro_rules! bit_relations_inherent_impls {
 #[cfg_attr(feature = "nightly", derive(Decodable_NoContext, Encodable_NoContext))]
 #[derive(Eq, PartialEq, Hash)]
 pub struct DenseBitSet<T> {
-    raw: RawBitSet<Vec<Word>>,
+    raw: RawBitSet<Box<[Word]>>,
     marker: PhantomData<T>,
 }
 
@@ -251,7 +251,7 @@ impl<T: Idx> BitRelations<DenseBitSet<T>> for DenseBitSet<T> {
 impl<T: Idx> From<GrowableBitSet<T>> for DenseBitSet<T> {
     fn from(bit_set: GrowableBitSet<T>) -> Self {
         let GrowableBitSet { raw, marker } = bit_set;
-        DenseBitSet { raw, marker }
+        DenseBitSet { raw: raw.adjust_words_storage(Vec::into_boxed_slice), marker }
     }
 }
 
@@ -1156,7 +1156,7 @@ impl<T: Idx> GrowableBitSet<T> {
 impl<T: Idx> From<DenseBitSet<T>> for GrowableBitSet<T> {
     fn from(bit_set: DenseBitSet<T>) -> Self {
         let DenseBitSet { raw, marker } = bit_set;
-        GrowableBitSet { raw, marker }
+        GrowableBitSet { raw: raw.adjust_words_storage(<[_]>::into_vec), marker }
     }
 }
 

compiler/rustc_index/src/bit_set/raw.rs

@@ -33,9 +33,7 @@ impl<W> RawBitSet<W> {
     pub(crate) fn domain_size(&self) -> usize {
         self.domain_size
     }
-}
 
-impl<W> RawBitSet<W> {
     pub(crate) fn new_empty_in(
         domain_size: usize,
         alloc_words: impl FnOnce(usize, Word) -> W,
@@ -45,13 +43,14 @@ impl<W> RawBitSet<W> {
 
         RawBitSet { domain_size, words }
     }
-}
 
-impl<W: AsMut<[Word]>> RawBitSet<W> {
     pub(crate) fn new_filled_in(
         domain_size: usize,
         alloc_words: impl FnOnce(usize, Word) -> W,
-    ) -> Self {
+    ) -> Self
+    where
+        W: AsMut<[Word]>,
+    {
         let num_words = num_words(domain_size);
         let words = alloc_words(num_words, !0);
 
@@ -60,19 +59,30 @@ impl<W: AsMut<[Word]>> RawBitSet<W> {
 
         this
     }
+
+    pub(crate) fn adjust_words_storage<W2>(
+        self,
+        adjust_words: impl FnOnce(W) -> W2,
+    ) -> RawBitSet<W2> {
+        let Self { domain_size, words } = self;
+        RawBitSet { domain_size, words: adjust_words(words) }
+    }
 }
 
-impl RawBitSet<Vec<Word>> {
+impl<W: From<Vec<Word>>> RawBitSet<W> {
     /// Creates a new, empty bitset with a given `domain_size`.
     #[inline]
     pub(crate) fn new_empty(domain_size: usize) -> Self {
-        Self::new_empty_in(domain_size, |num_words, w| vec![w; num_words])
+        Self::new_empty_in(domain_size, |num_words, w| W::from(vec![w; num_words]))
     }
 
     /// Creates a new, filled bitset with a given `domain_size`.
     #[inline]
-    pub(crate) fn new_filled(domain_size: usize) -> Self {
-        Self::new_filled_in(domain_size, |num_words, w| vec![w; num_words])
+    pub(crate) fn new_filled(domain_size: usize) -> Self
+    where
+        W: AsMut<[Word]>,
+    {
+        Self::new_filled_in(domain_size, |num_words, w| W::from(vec![w; num_words]))
     }
 }