.bcx
.ins()
.iconst(fx.pointer_type, len.eval_usize(fx.tcx, ParamEnv::reveal_all()) as i64),
- (&ty::Dynamic(..), &ty::Dynamic(..)) => {
- // For now, upcasts are limited to changes in marker
- // traits, and hence never actually require an actual
- // change to the vtable.
- old_info.expect("unsized_info: missing old info for trait upcast")
- }
- (_, &ty::Dynamic(ref data, ..)) => {
- crate::vtable::get_vtable(fx, fx.layout_of(source), data.principal())
+ (&ty::Dynamic(ref data_a, ..), &ty::Dynamic(ref data_b, ..)) => {
+ let old_info =
+ old_info.expect("unsized_info: missing old info for trait upcasting coercion");
+ if data_a.principal_def_id() == data_b.principal_def_id() {
+ return old_info;
+ }
+
+ // trait upcasting coercion
+ let vptr_entry_idx =
+ fx.tcx.vtable_trait_upcasting_coercion_new_vptr_slot((source, target));
+
+ if let Some(entry_idx) = vptr_entry_idx {
+ let entry_idx = u32::try_from(entry_idx).unwrap();
+ let entry_offset = entry_idx * fx.pointer_type.bytes();
+ let vptr_ptr = Pointer::new(old_info).offset_i64(fx, entry_offset.into()).load(
+ fx,
+ fx.pointer_type,
+ crate::vtable::vtable_memflags(),
+ );
+ vptr_ptr
+ } else {
+ old_info
+ }
}
+ (_, &ty::Dynamic(ref data, ..)) => crate::vtable::get_vtable(fx, source, data.principal()),
_ => bug!("unsized_info: invalid unsizing {:?} -> {:?}", source, target),
}
}
-/// Coerce `src` to `dst_ty`. `src_ty` must be a thin pointer.
-fn unsize_thin_ptr<'tcx>(
+/// Coerce `src` to `dst_ty`.
+fn unsize_ptr<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
src: Value,
src_layout: TyAndLayout<'tcx>,
dst_layout: TyAndLayout<'tcx>,
+ old_info: Option<Value>,
) -> (Value, Value) {
match (&src_layout.ty.kind(), &dst_layout.ty.kind()) {
(&ty::Ref(_, a, _), &ty::Ref(_, b, _))
| (&ty::Ref(_, a, _), &ty::RawPtr(ty::TypeAndMut { ty: b, .. }))
| (&ty::RawPtr(ty::TypeAndMut { ty: a, .. }), &ty::RawPtr(ty::TypeAndMut { ty: b, .. })) => {
- assert!(!fx.layout_of(a).is_unsized());
- (src, unsized_info(fx, a, b, None))
+ (src, unsized_info(fx, *a, *b, old_info))
}
(&ty::Adt(def_a, _), &ty::Adt(def_b, _)) if def_a.is_box() && def_b.is_box() => {
let (a, b) = (src_layout.ty.boxed_ty(), dst_layout.ty.boxed_ty());
- assert!(!fx.layout_of(a).is_unsized());
- (src, unsized_info(fx, a, b, None))
+ (src, unsized_info(fx, a, b, old_info))
}
(&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => {
assert_eq!(def_a, def_b);
+ if src_layout == dst_layout {
+ return (src, old_info.unwrap());
+ }
+
let mut result = None;
for i in 0..src_layout.fields.count() {
let src_f = src_layout.field(fx, i);
let dst_f = dst_layout.field(fx, i);
assert_ne!(src_f.ty, dst_f.ty);
assert_eq!(result, None);
- result = Some(unsize_thin_ptr(fx, src, src_f, dst_f));
+ result = Some(unsize_ptr(fx, src, src_f, dst_f, old_info));
}
result.unwrap()
}
- _ => bug!("unsize_thin_ptr: called on bad types"),
+ _ => bug!("unsize_ptr: called on bad types"),
}
}
let mut coerce_ptr = || {
let (base, info) =
if fx.layout_of(src.layout().ty.builtin_deref(true).unwrap().ty).is_unsized() {
- // fat-ptr to fat-ptr unsize preserves the vtable
- // i.e., &'a fmt::Debug+Send => &'a fmt::Debug
- src.load_scalar_pair(fx)
+ let (old_base, old_info) = src.load_scalar_pair(fx);
+ unsize_ptr(fx, old_base, src.layout(), dst.layout(), Some(old_info))
} else {
let base = src.load_scalar(fx);
- unsize_thin_ptr(fx, base, src.layout(), dst.layout())
+ unsize_ptr(fx, base, src.layout(), dst.layout(), None)
};
dst.write_cvalue(fx, CValue::by_val_pair(base, info, dst.layout()));
};
(&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => {
assert_eq!(def_a, def_b);
- for i in 0..def_a.variants[VariantIdx::new(0)].fields.len() {
+ for i in 0..def_a.variant(VariantIdx::new(0)).fields.len() {
let src_f = src.value_field(fx, mir::Field::new(i));
let dst_f = dst.place_field(fx, mir::Field::new(i));
// Packed types ignore the alignment of their fields.
if let ty::Adt(def, _) = layout.ty.kind() {
- if def.repr.packed() {
+ if def.repr().packed() {
unsized_align = sized_align;
}
}