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Elide storage markers when elaborating deref projections

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This commit is contained in:
Tomasz Miąsko 2022-07-30 00:00:00 +00:00
parent 943a380b37
commit 162bd16352
2 changed files with 7 additions and 22 deletions
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20
compiler/rustc_mir_transform/src/deref_separator.rs
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@ -28,8 +28,6 @@ impl<'tcx> MutVisitor<'tcx> for DerefChecker<'tcx> {
let mut last_len = 0;
let mut last_deref_idx = 0;
let mut prev_temp: Option<Local> = None;
for (idx, elem) in place.projection[0..].iter().enumerate() {
if *elem == ProjectionElem::Deref {
last_deref_idx = idx;
@ -39,14 +37,12 @@ impl<'tcx> MutVisitor<'tcx> for DerefChecker<'tcx> {
for (idx, (p_ref, p_elem)) in place.iter_projections().enumerate() {
if !p_ref.projection.is_empty() && p_elem == ProjectionElem::Deref {
let ty = p_ref.ty(&self.local_decls, self.tcx).ty;
let temp = self.patcher.new_local_with_info(
let temp = self.patcher.new_internal_with_info(
ty,
self.local_decls[p_ref.local].source_info.span,
Some(Box::new(LocalInfo::DerefTemp)),
);
self.patcher.add_statement(loc, StatementKind::StorageLive(temp));
// We are adding current p_ref's projections to our
// temp value, excluding projections we already covered.
let deref_place = Place::from(place_local)
@ -66,22 +62,8 @@ impl<'tcx> MutVisitor<'tcx> for DerefChecker<'tcx> {
Place::from(temp).project_deeper(&place.projection[idx..], self.tcx);
*place = temp_place;
}
// We are destroying the previous temp since it's no longer used.
if let Some(prev_temp) = prev_temp {
self.patcher.add_statement(loc, StatementKind::StorageDead(prev_temp));
}
prev_temp = Some(temp);
}
}
// Since we won't be able to reach final temp, we destroy it outside the loop.
if let Some(prev_temp) = prev_temp {
let last_loc =
Location { block: loc.block, statement_index: loc.statement_index + 1 };
self.patcher.add_statement(last_loc, StatementKind::StorageDead(prev_temp));
}
}
}
}