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stricter alignment enforcement for ScalarPair and Vector

This commit is contained in:
Ralf Jung 2022-11-28 10:45:22 +01:00
parent 58dd62a756
commit 891a4da4f3
1 changed files with 22 additions and 15 deletions
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37
compiler/rustc_ty_utils/src/layout_sanity_check.rs
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@ -135,22 +135,24 @@ pub(super) fn sanity_check_layout<'tcx>(
}
}
Abi::ScalarPair(scalar1, scalar2) => {
// Sanity-check scalar pairs. These are a bit more flexible and support
// padding, but we can at least ensure both fields actually fit into the layout
// and the alignment requirement has not been weakened.
// Sanity-check scalar pairs. Computing the expected size and alignment is a bit of work.
let size1 = scalar1.size(cx);
let align1 = scalar1.align(cx).abi;
let size2 = scalar2.size(cx);
let align2 = scalar2.align(cx).abi;
assert!(
layout.layout.align().abi >= cmp::max(align1, align2),
"alignment mismatch between ABI and layout in {layout:#?}",
);
let align = cmp::max(align1, align2);
let field2_offset = size1.align_to(align2);
assert!(
layout.layout.size() >= field2_offset + size2,
let size = (field2_offset + size2).align_to(align);
assert_eq!(
layout.layout.size(),
size,
"size mismatch between ABI and layout in {layout:#?}"
);
assert_eq!(
layout.layout.align().abi,
align,
"alignment mismatch between ABI and layout in {layout:#?}",
);
// Check that the underlying pair of fields matches.
let inner = skip_newtypes(cx, layout);
assert!(
@ -233,17 +235,22 @@ pub(super) fn sanity_check_layout<'tcx>(
);
}
Abi::Vector { count, element } => {
// No padding in vectors. Alignment can be strengthened, though.
assert!(
layout.layout.align().abi >= element.align(cx).abi,
"alignment mismatch between ABI and layout in {layout:#?}"
);
// No padding in vectors, except possibly for trailing padding to make the size a multiple of align.
let size = element.size(cx) * count;
let align = cx.data_layout().vector_align(size).abi;
let size = size.align_to(align); // needed e.g. for vectors of size 3
assert!(align >= element.align(cx).abi); // just sanity-checking `vector_align`.
assert_eq!(
layout.layout.size(),
size.align_to(cx.data_layout().vector_align(size).abi),
size,
"size mismatch between ABI and layout in {layout:#?}"
);
assert_eq!(
layout.layout.align().abi,
align,
"alignment mismatch between ABI and layout in {layout:#?}"
);
// FIXME: Do some kind of check of the inner type, like for Scalar and ScalarPair.
}
Abi::Uninhabited | Abi::Aggregate { .. } => {} // Nothing to check.
}