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Use let/else to de-indent ElaborateBoxDerefs::run_pass.

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This commit is contained in:
Nicholas Nethercote 2024-09-09 08:49:47 +10:00
parent cc09ab3c75
commit 181fbd5ce8
1 changed files with 39 additions and 42 deletions
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81
compiler/rustc_mir_transform/src/elaborate_box_derefs.rs
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@ -92,64 +92,61 @@ pub(super) struct ElaborateBoxDerefs;
impl<'tcx> crate::MirPass<'tcx> for ElaborateBoxDerefs {
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
if let Some(def_id) = tcx.lang_items().owned_box() {
let unique_did = tcx.adt_def(def_id).non_enum_variant().fields[FieldIdx::ZERO].did;
// If box is not present, this pass doesn't need to do anything.
let Some(def_id) = tcx.lang_items().owned_box() else { return };
let Some(nonnull_def) = tcx.type_of(unique_did).instantiate_identity().ty_adt_def()
else {
span_bug!(tcx.def_span(unique_did), "expected Box to contain Unique")
};
let unique_did = tcx.adt_def(def_id).non_enum_variant().fields[FieldIdx::ZERO].did;
let nonnull_did = nonnull_def.non_enum_variant().fields[FieldIdx::ZERO].did;
let Some(nonnull_def) = tcx.type_of(unique_did).instantiate_identity().ty_adt_def() else {
span_bug!(tcx.def_span(unique_did), "expected Box to contain Unique")
};
let patch = MirPatch::new(body);
let nonnull_did = nonnull_def.non_enum_variant().fields[FieldIdx::ZERO].did;
let local_decls = &mut body.local_decls;
let patch = MirPatch::new(body);
let mut visitor =
ElaborateBoxDerefVisitor { tcx, unique_did, nonnull_did, local_decls, patch };
let local_decls = &mut body.local_decls;
for (block, data) in body.basic_blocks.as_mut_preserves_cfg().iter_enumerated_mut() {
visitor.visit_basic_block_data(block, data);
}
let mut visitor =
ElaborateBoxDerefVisitor { tcx, unique_did, nonnull_did, local_decls, patch };
visitor.patch.apply(body);
for (block, data) in body.basic_blocks.as_mut_preserves_cfg().iter_enumerated_mut() {
visitor.visit_basic_block_data(block, data);
}
for debug_info in body.var_debug_info.iter_mut() {
if let VarDebugInfoContents::Place(place) = &mut debug_info.value {
let mut new_projections: Option<Vec<_>> = None;
visitor.patch.apply(body);
for (base, elem) in place.iter_projections() {
let base_ty = base.ty(&body.local_decls, tcx).ty;
for debug_info in body.var_debug_info.iter_mut() {
if let VarDebugInfoContents::Place(place) = &mut debug_info.value {
let mut new_projections: Option<Vec<_>> = None;
if let PlaceElem::Deref = elem
&& let Some(boxed_ty) = base_ty.boxed_ty()
{
// Clone the projections before us, since now we need to mutate them.
let new_projections =
new_projections.get_or_insert_with(|| base.projection.to_vec());
for (base, elem) in place.iter_projections() {
let base_ty = base.ty(&body.local_decls, tcx).ty;
let (unique_ty, nonnull_ty, ptr_ty) =
build_ptr_tys(tcx, boxed_ty, unique_did, nonnull_did);
if let PlaceElem::Deref = elem
&& let Some(boxed_ty) = base_ty.boxed_ty()
{
// Clone the projections before us, since now we need to mutate them.
let new_projections =
new_projections.get_or_insert_with(|| base.projection.to_vec());
new_projections.extend_from_slice(&build_projection(
unique_ty, nonnull_ty, ptr_ty,
));
new_projections.push(PlaceElem::Deref);
} else if let Some(new_projections) = new_projections.as_mut() {
// Keep building up our projections list once we've started it.
new_projections.push(elem);
}
}
let (unique_ty, nonnull_ty, ptr_ty) =
build_ptr_tys(tcx, boxed_ty, unique_did, nonnull_did);
// Store the mutated projections if we actually changed something.
if let Some(new_projections) = new_projections {
place.projection = tcx.mk_place_elems(&new_projections);
new_projections
.extend_from_slice(&build_projection(unique_ty, nonnull_ty, ptr_ty));
new_projections.push(PlaceElem::Deref);
} else if let Some(new_projections) = new_projections.as_mut() {
// Keep building up our projections list once we've started it.
new_projections.push(elem);
}
}
// Store the mutated projections if we actually changed something.
if let Some(new_projections) = new_projections {
place.projection = tcx.mk_place_elems(&new_projections);
}
}
} else {
// box is not present, this pass doesn't need to do anything
}
}
}