nordic-dev.net/rust
nordic-dev.net/rust
2
0
Fork 0
mirror of https://github.com/rust-lang/rust.git synced 2025-02-04 02:54:00 +00:00
Code Issues Packages Projects Releases Wiki Activity

also sanity-check Abi::Vector, and slight refactoring

Browse Source
This commit is contained in:
Ralf Jung 2022-05-09 20:13:25 +02:00
parent 04fb9222f8
commit 02eca34534
1 changed files with 44 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

61
compiler/rustc_middle/src/ty/layout.rs
View File

@ -248,16 +248,36 @@ fn sanity_check_layout<'tcx>(
"size mismatch between ABI and layout in {layout:#?}"
);*/
}
Abi::ScalarPair(scalar1, scalar2) => {
// Sanity-check scalar pair size.
let field2_offset = scalar1.size(&tcx).align_to(scalar2.align(&tcx).abi);
let total = field2_offset + scalar2.size(&tcx);
Abi::Vector { count, element } => {
// No padding in vectors. Alignment can be strengthened, though.
assert!(
layout.size() >= total,
layout.align().abi >= element.align(&tcx).abi,
"alignment mismatch between ABI and layout in {layout:#?}"
);
let size = element.size(&tcx) * count;
assert_eq!(
layout.size(),
size.align_to(tcx.data_layout().vector_align(size).abi),
"size mismatch between ABI and layout in {layout:#?}"
);
}
_ => {}
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.
let align1 = scalar1.align(&tcx).abi;
let align2 = scalar2.align(&tcx).abi;
assert!(
layout.align().abi >= cmp::max(align1, align2),
"alignment mismatch between ABI and layout in {layout:#?}",
);
let field2_offset = scalar1.size(&tcx).align_to(align2);
assert!(
layout.size() >= field2_offset + scalar2.size(&tcx),
"size mismatch between ABI and layout in {layout:#?}"
);
}
Abi::Uninhabited | Abi::Aggregate { .. } => {} // Nothing to check.
}
}
@ -1401,16 +1421,6 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
// Without latter check aligned enums with custom discriminant values
// Would result in ICE see the issue #92464 for more info
abi = Abi::Scalar(tag);
// Make sure the variants with fields have the same ABI as the enum itself
// (since downcasting to them is a NOP).
for variant in &mut layout_variants {
if variant.fields.count() > 0
&& matches!(variant.abi, Abi::Aggregate { .. })
{
assert_eq!(variant.size, size);
variant.abi = abi;
}
}
} else {
// Try to use a ScalarPair for all tagged enums.
let mut common_prim = None;
@ -1479,17 +1489,24 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
// We can use `ScalarPair` only when it matches our
// already computed layout (including `#[repr(C)]`).
abi = pair.abi;
// Make sure the variants with fields have the same ABI as the enum itself
// (since downcasting to them is a NOP).
}
}
}
// If we pick a "clever" (by-value) ABI, we might have to adjust the ABI of the
// variants to ensure they are consistent. This is because a downcast is
// semantically a NOP, and thus should not affect layout.
if matches!(abi, Abi::Scalar(..) | Abi::ScalarPair(..)) {
for variant in &mut layout_variants {
// We only do this for variants with fields; the others are not accessed anyway.
// Also do not overwrite any already existing "clever" ABIs.
if variant.fields.count() > 0
&& matches!(variant.abi, Abi::Aggregate { .. })
{
variant.abi = abi;
// Also need to bump up the size, so that the pair fits inside.
variant.size = size;
}
}
// Also need to bump up the size and alignment, so that the entire value fits in here.
variant.size = cmp::max(variant.size, size);
variant.align.abi = cmp::max(variant.align.abi, align.abi);
}
}
}