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Use IndexVec for coroutine local mapping #127293

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Jul 4, 2024
Merged

Use IndexVec for coroutine local mapping #127293

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5 changes: 5 additions & 0 deletions compiler/rustc_index/src/vec.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -208,6 +208,11 @@ impl<I: Idx, T> IndexVec<I, Option<T>> {
pub fn remove(&mut self, index: I) -> Option<T> {
self.get_mut(index)?.take()
}

#[inline]
pub fn contains(&self, index: I) -> bool {
self.get(index).and_then(Option::as_ref).is_some()
}
}

impl<I: Idx, T: fmt::Debug> fmt::Debug for IndexVec<I, T> {
Expand Down
35 changes: 16 additions & 19 deletions compiler/rustc_mir_transform/src/coroutine.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -58,7 +58,7 @@ use crate::deref_separator::deref_finder;
use crate::errors;
use crate::pass_manager as pm;
use crate::simplify;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::pluralize;
use rustc_hir as hir;
use rustc_hir::lang_items::LangItem;
Expand Down Expand Up @@ -236,8 +236,7 @@ struct TransformVisitor<'tcx> {
discr_ty: Ty<'tcx>,

// Mapping from Local to (type of local, coroutine struct index)
// FIXME(eddyb) This should use `IndexVec<Local, Option<_>>`.
remap: FxHashMap<Local, (Ty<'tcx>, VariantIdx, FieldIdx)>,
remap: IndexVec<Local, Option<(Ty<'tcx>, VariantIdx, FieldIdx)>>,

// A map from a suspension point in a block to the locals which have live storage at that point
storage_liveness: IndexVec<BasicBlock, Option<BitSet<Local>>>,
Expand Down Expand Up @@ -485,7 +484,7 @@ impl<'tcx> MutVisitor<'tcx> for TransformVisitor<'tcx> {
}

fn visit_local(&mut self, local: &mut Local, _: PlaceContext, _: Location) {
assert_eq!(self.remap.get(local), None);
assert!(!self.remap.contains(*local));
}

fn visit_place(
Expand All @@ -495,7 +494,7 @@ impl<'tcx> MutVisitor<'tcx> for TransformVisitor<'tcx> {
_location: Location,
) {
// Replace an Local in the remap with a coroutine struct access
if let Some(&(ty, variant_index, idx)) = self.remap.get(&place.local) {
if let Some(&Some((ty, variant_index, idx))) = self.remap.get(place.local) {
replace_base(place, self.make_field(variant_index, idx, ty), self.tcx);
}
}
Expand All @@ -504,7 +503,7 @@ impl<'tcx> MutVisitor<'tcx> for TransformVisitor<'tcx> {
// Remove StorageLive and StorageDead statements for remapped locals
data.retain_statements(|s| match s.kind {
StatementKind::StorageLive(l) | StatementKind::StorageDead(l) => {
!self.remap.contains_key(&l)
!self.remap.contains(l)
}
_ => true,
});
Expand All @@ -529,21 +528,17 @@ impl<'tcx> MutVisitor<'tcx> for TransformVisitor<'tcx> {

// The resume arg target location might itself be remapped if its base local is
// live across a yield.
let resume_arg =
if let Some(&(ty, variant, idx)) = self.remap.get(&resume_arg.local) {
replace_base(&mut resume_arg, self.make_field(variant, idx, ty), self.tcx);
resume_arg
} else {
resume_arg
};
if let Some(&Some((ty, variant, idx))) = self.remap.get(resume_arg.local) {
replace_base(&mut resume_arg, self.make_field(variant, idx, ty), self.tcx);
}

let storage_liveness: GrowableBitSet<Local> =
self.storage_liveness[block].clone().unwrap().into();

for i in 0..self.always_live_locals.domain_size() {
let l = Local::new(i);
let needs_storage_dead = storage_liveness.contains(l)
&& !self.remap.contains_key(&l)
&& !self.remap.contains(l)
&& !self.always_live_locals.contains(l);
if needs_storage_dead {
data.statements
Expand Down Expand Up @@ -1037,7 +1032,7 @@ fn compute_layout<'tcx>(
liveness: LivenessInfo,
body: &Body<'tcx>,
) -> (
FxHashMap<Local, (Ty<'tcx>, VariantIdx, FieldIdx)>,
IndexVec<Local, Option<(Ty<'tcx>, VariantIdx, FieldIdx)>>,
CoroutineLayout<'tcx>,
IndexVec<BasicBlock, Option<BitSet<Local>>>,
) {
Expand Down Expand Up @@ -1098,7 +1093,7 @@ fn compute_layout<'tcx>(
// Create a map from local indices to coroutine struct indices.
let mut variant_fields: IndexVec<VariantIdx, IndexVec<FieldIdx, CoroutineSavedLocal>> =
iter::repeat(IndexVec::new()).take(RESERVED_VARIANTS).collect();
let mut remap = FxHashMap::default();
let mut remap = IndexVec::from_elem_n(None, saved_locals.domain_size());
for (suspension_point_idx, live_locals) in live_locals_at_suspension_points.iter().enumerate() {
let variant_index = VariantIdx::from(RESERVED_VARIANTS + suspension_point_idx);
let mut fields = IndexVec::new();
Expand All @@ -1109,7 +1104,7 @@ fn compute_layout<'tcx>(
// around inside coroutines, so it doesn't matter which variant
// index we access them by.
let idx = FieldIdx::from_usize(idx);
remap.entry(locals[saved_local]).or_insert((tys[saved_local].ty, variant_index, idx));
remap[locals[saved_local]] = Some((tys[saved_local].ty, variant_index, idx));
}
variant_fields.push(fields);
variant_source_info.push(source_info_at_suspension_points[suspension_point_idx]);
Expand All @@ -1121,7 +1116,9 @@ fn compute_layout<'tcx>(
for var in &body.var_debug_info {
let VarDebugInfoContents::Place(place) = &var.value else { continue };
let Some(local) = place.as_local() else { continue };
let Some(&(_, variant, field)) = remap.get(&local) else { continue };
let Some(&Some((_, variant, field))) = remap.get(local) else {
continue;
};

let saved_local = variant_fields[variant][field];
field_names.get_or_insert_with(saved_local, || var.name);
Expand Down Expand Up @@ -1524,7 +1521,7 @@ fn create_cases<'tcx>(
for i in 0..(body.local_decls.len()) {
let l = Local::new(i);
let needs_storage_live = point.storage_liveness.contains(l)
&& !transform.remap.contains_key(&l)
&& !transform.remap.contains(l)
&& !transform.always_live_locals.contains(l);
if needs_storage_live {
statements
Expand Down
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