Reduce rightward drift in locals_live_across_suspend_points

Author: yotamofek

compiler/rustc_mir_transform/src/coroutine.rs

@@ -735,53 +735,53 @@ fn locals_live_across_suspend_points<'tcx>(
  let mut live_locals_at_any_suspension_point = DenseBitSet::new_empty(body.local_decls.len());
 
  for (block, data) in body.basic_blocks.iter_enumerated() {
- if let TerminatorKind::Yield { .. } = data.terminator().kind {
- let loc = Location { block, statement_index: data.statements.len() };
-
- liveness.seek_to_block_end(block);
- let mut live_locals = liveness.get().clone();
-
- if !movable {
- // The `liveness` variable contains the liveness of MIR locals ignoring borrows.
- // This is correct for movable coroutines since borrows cannot live across
- // suspension points. However for immovable coroutines we need to account for
- // borrows, so we conservatively assume that all borrowed locals are live until
- // we find a StorageDead statement referencing the locals.
- // To do this we just union our `liveness` result with `borrowed_locals`, which
- // contains all the locals which has been borrowed before this suspension point.
- // If a borrow is converted to a raw reference, we must also assume that it lives
- // forever. Note that the final liveness is still bounded by the storage liveness
- // of the local, which happens using the `intersect` operation below.
- borrowed_locals_cursor2.seek_before_primary_effect(loc);
- live_locals.union(borrowed_locals_cursor2.get());
- }
+ let TerminatorKind::Yield { .. } = data.terminator().kind else { continue };
+
+ let loc = Location { block, statement_index: data.statements.len() };
+
+ liveness.seek_to_block_end(block);
+ let mut live_locals = liveness.get().clone();
+
+ if !movable {
+ // The `liveness` variable contains the liveness of MIR locals ignoring borrows.
+ // This is correct for movable coroutines since borrows cannot live across
+ // suspension points. However for immovable coroutines we need to account for
+ // borrows, so we conservatively assume that all borrowed locals are live until
+ // we find a StorageDead statement referencing the locals.
+ // To do this we just union our `liveness` result with `borrowed_locals`, which
+ // contains all the locals which has been borrowed before this suspension point.
+ // If a borrow is converted to a raw reference, we must also assume that it lives
+ // forever. Note that the final liveness is still bounded by the storage liveness
+ // of the local, which happens using the `intersect` operation below.
+ borrowed_locals_cursor2.seek_before_primary_effect(loc);
+ live_locals.union(borrowed_locals_cursor2.get());
+ }
 
-  // Store the storage liveness for later use so we can restore the state
-  // after a suspension point
-  storage_live.seek_before_primary_effect(loc);
-  storage_liveness_map[block] = Some(storage_live.get().clone());
+ // Store the storage liveness for later use so we can restore the state
+ // after a suspension point
+ storage_live.seek_before_primary_effect(loc);
+ storage_liveness_map[block] = Some(storage_live.get().clone());
 
-  // Locals live are live at this point only if they are used across
-  // suspension points (the `liveness` variable)
-  // and their storage is required (the `storage_required` variable)
-  requires_storage_cursor.seek_before_primary_effect(loc);
-  live_locals.intersect(requires_storage_cursor.get());
+ // Locals live are live at this point only if they are used across
+ // suspension points (the `liveness` variable)
+ // and their storage is required (the `storage_required` variable)
+ requires_storage_cursor.seek_before_primary_effect(loc);
+ live_locals.intersect(requires_storage_cursor.get());
 
-  // The coroutine argument is ignored.
-  live_locals.remove(SELF_ARG);
+ // The coroutine argument is ignored.
+ live_locals.remove(SELF_ARG);
 
-  debug!("loc = {:?}, live_locals = {:?}", loc, live_locals);
+ debug!(?loc, ?live_locals);
 
-  // Add the locals live at this suspension point to the set of locals which live across
-  // any suspension points
-  live_locals_at_any_suspension_point.union(&live_locals);
+ // Add the locals live at this suspension point to the set of locals which live across
+ // any suspension points
+ live_locals_at_any_suspension_point.union(&live_locals);
 
- live_locals_at_suspension_points.push(live_locals);
- source_info_at_suspension_points.push(data.terminator().source_info);
- }
+ live_locals_at_suspension_points.push(live_locals);
+ source_info_at_suspension_points.push(data.terminator().source_info);
  }
 
- debug!("live_locals_anywhere = {:?}", live_locals_at_any_suspension_point);
+ debug!(?live_locals_at_any_suspension_point);
  let saved_locals = CoroutineSavedLocals(live_locals_at_any_suspension_point);
 
  // Renumber our liveness_map bitsets to include only the locals we are