bjoernager/rust
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Get rid of niche selection's dependence on fields's order

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This commit is contained in:
Adwin White 2024-09-18 17:30:27 +08:00
parent f6bcd094ab
commit 9ac23dde37
2 changed files with 24 additions and 9 deletions
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13
compiler/rustc_abi/src/layout.rs
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@ -527,15 +527,10 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
let count =
(niche_variants.end().index() as u128 - niche_variants.start().index() as u128) + 1;
// Find the field with the largest niche
let (field_index, niche, (niche_start, niche_scalar)) = variants[largest_variant_index]
.iter()
.enumerate()
.filter_map(|(j, field)| Some((j, field.largest_niche?)))
.max_by_key(|(_, niche)| niche.available(dl))
.and_then(|(j, niche)| Some((j, niche, niche.reserve(dl, count)?)))?;
let niche_offset =
niche.offset + variant_layouts[largest_variant_index].fields.offset(field_index);
// Use the largest niche in the largest variant.
let niche = variant_layouts[largest_variant_index].largest_niche?;
let (niche_start, niche_scalar) = niche.reserve(dl, count)?;
let niche_offset = niche.offset;
let niche_size = niche.value.size(dl);
let size = variant_layouts[largest_variant_index].size.align_to(align.abi);