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rustc_trans: treat General enums like unions.

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This commit is contained in:
Eduard-Mihai Burtescu 2017-09-13 23:18:40 +03:00
parent 9a0efea4c2
commit 30710609c0
3 changed files with 10 additions and 27 deletions
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29
src/librustc_trans/adt.rs
View File

@ -148,36 +148,15 @@ fn generic_type_of<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
}
}
}
layout::General { discr, size, align, primitive_align, .. } => {
// We need a representation that has:
// * The alignment of the most-aligned field
// * The size of the largest variant (rounded up to that alignment)
// * No alignment padding anywhere any variant has actual data
// (currently matters only for enums small enough to be immediate)
// * The discriminant in an obvious place.
//
// So we start with the discriminant, pad it up to the alignment with
// more of its own type, then use alignment-sized ints to get the rest
// of the size.
let discr_ty = Type::from_integer(cx, discr);
let discr_size = discr.size().bytes();
let padded_discr_size = discr.size().abi_align(align);
let variant_part_size = size - padded_discr_size;
// Ensure discr_ty can fill pad evenly
assert_eq!(padded_discr_size.bytes() % discr_size, 0);
let fields = [
discr_ty,
Type::array(&discr_ty, padded_discr_size.bytes() / discr_size - 1),
union_fill(cx, variant_part_size, primitive_align)
];
layout::General { size, align, .. } => {
let fill = union_fill(cx, size, align);
match name {
None => {
Type::struct_(cx, &fields, false)
Type::struct_(cx, &[fill], false)
}
Some(name) => {
let mut llty = Type::named_struct(cx, name);
llty.set_struct_body(&fields, false);
llty.set_struct_body(&[fill], false);
llty
}
}

5
src/librustc_trans/mir/lvalue.rs
View File

@ -216,6 +216,11 @@ impl<'a, 'tcx> LvalueRef<'tcx> {
return LvalueRef::new_sized(
bcx.pointercast(self.llval, ty.ptr_to()), fty, alignment);
}
layout::General { .. } if l.variant_index.is_none() => {
let ty = ccx.llvm_type_of(fty);
return LvalueRef::new_sized(
bcx.pointercast(self.llval, ty.ptr_to()), fty, alignment);
}
layout::RawNullablePointer { nndiscr, .. } |
layout::StructWrappedNullablePointer { nndiscr, .. }
if l.variant_index.unwrap() as u64 != nndiscr => {

3
src/librustc_trans/type_of.rs
View File

@ -262,8 +262,7 @@ impl<'tcx> LayoutLlvmExt for FullLayout<'tcx> {
if let Some(v) = self.variant_index {
adt::memory_index_to_gep(variants[v].memory_index[index] as u64)
} else {
assert_eq!(index, 0);
index as u64
bug!("FullLayout::llvm_field_index({:?}): not applicable", self)
}
}