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Simplify last prepare_vtable_segments loop even more

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Maybe Waffle 2023-07-19 10:34:35 +00:00
parent d567f0fc68
commit d87db8eb3f
1 changed files with 21 additions and 24 deletions
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31
compiler/rustc_trait_selection/src/traits/vtable.rs
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@ -113,7 +113,7 @@ fn prepare_vtable_segments_inner<'tcx, T>(
// Loop run #1: Emitting the slice [D C] (in reverse order). No one has a next-sibling node. // Loop run #1: Emitting the slice [D C] (in reverse order). No one has a next-sibling node.
// Loop run #1: Stack after exiting out is []. Now the function exits. // Loop run #1: Stack after exiting out is []. Now the function exits.
loop { 'outer: loop {
// dive deeper into the stack, recording the path // dive deeper into the stack, recording the path
'diving_in: loop { 'diving_in: loop {
let &(inner_most_trait_ref, _, _) = stack.last().unwrap(); let &(inner_most_trait_ref, _, _) = stack.last().unwrap();
@ -151,33 +151,30 @@ fn prepare_vtable_segments_inner<'tcx, T>(
emit_vptr_on_new_entry = true; emit_vptr_on_new_entry = true;
// emit innermost item, move to next sibling and stop there if possible, otherwise jump to outer level. // emit innermost item, move to next sibling and stop there if possible, otherwise jump to outer level.
'exiting_out: loop { while let Some((inner_most_trait_ref, emit_vptr, mut siblings)) = stack.pop() {
if let Some((inner_most_trait_ref, emit_vptr, siblings)) = stack.last_mut() {
segment_visitor(VtblSegment::TraitOwnEntries { segment_visitor(VtblSegment::TraitOwnEntries {
trait_ref: *inner_most_trait_ref, trait_ref: inner_most_trait_ref,
emit_vptr: *emit_vptr, emit_vptr,
})?; })?;
match siblings.find(|&sibling| visited.insert(sibling.to_predicate(tcx))) { if let Some(next_inner_most_trait_ref) =
Some(next_inner_most_trait_ref) => { siblings.find(|&sibling| visited.insert(sibling.to_predicate(tcx)))
{
// We're throwing away potential constness of super traits here. // We're throwing away potential constness of super traits here.
// FIXME: handle ~const super traits // FIXME: handle ~const super traits
let next_inner_most_trait_ref = let next_inner_most_trait_ref =
next_inner_most_trait_ref.map_bound(|t| t.trait_ref); next_inner_most_trait_ref.map_bound(|t| t.trait_ref);
*inner_most_trait_ref = next_inner_most_trait_ref;
*emit_vptr = emit_vptr_on_new_entry; stack.push((next_inner_most_trait_ref, emit_vptr_on_new_entry, siblings));
break 'exiting_out;
} // just pushed a new trait onto the stack, so we need to go through its super traits
None => { continue 'outer;
stack.pop();
continue 'exiting_out;
} }
} }
}
// all done // the stack is empty, all done
return ControlFlow::Continue(()); return ControlFlow::Continue(());
} }
}
} }
/// Turns option of iterator into an iterator (this is just flatten) /// Turns option of iterator into an iterator (this is just flatten)