Auto merge of #93984 - nnethercote:ChunkedBitSet, r=Mark-Simulacrum

Introduce `ChunkedBitSet` and use it for some dataflow analyses.

This reduces peak memory usage significantly for some programs with very
large functions.

r? `@ghost`

compiler/rustc_borrowck/src/lib.rs

@@ -22,7 +22,7 @@ use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorReported};
 use rustc_hir as hir;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::Node;
-use rustc_index::bit_set::BitSet;
+use rustc_index::bit_set::ChunkedBitSet;
 use rustc_index::vec::IndexVec;
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
 use rustc_middle::mir::{
@@ -1667,7 +1667,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         location: Location,
         desired_action: InitializationRequiringAction,
         place_span: (PlaceRef<'tcx>, Span),
-        maybe_uninits: &BitSet<MovePathIndex>,
+        maybe_uninits: &ChunkedBitSet<MovePathIndex>,
         from: u64,
         to: u64,
     ) {

compiler/rustc_data_structures/src/lib.rs

@@ -37,6 +37,8 @@ extern crate cfg_if;
 #[macro_use]
 extern crate rustc_macros;
 
+pub use rustc_index::static_assert_size;
+
 #[inline(never)]
 #[cold]
 pub fn cold_path<F: FnOnce() -> R, R>(f: F) -> R {

compiler/rustc_data_structures/src/macros.rs

@@ -1,11 +1,3 @@
-/// Type size assertion. The first argument is a type and the second argument is its expected size.
-#[macro_export]
-macro_rules! static_assert_size {
-    ($ty:ty, $size:expr) => {
-        const _: [(); $size] = [(); ::std::mem::size_of::<$ty>()];
-    };
-}
-
 #[macro_export]
 macro_rules! enum_from_u32 {
     ($(#[$attr:meta])* pub enum $name:ident {