297 lines
13 KiB
Rust
297 lines
13 KiB
Rust
use std::assert_matches::assert_matches;
|
|
|
|
use rustc_middle::bug;
|
|
use rustc_middle::ty::layout::{HasTyCtxt, LayoutCx, TyAndLayout};
|
|
use rustc_target::abi::*;
|
|
|
|
/// Enforce some basic invariants on layouts.
|
|
pub(super) fn sanity_check_layout<'tcx>(cx: &LayoutCx<'tcx>, layout: &TyAndLayout<'tcx>) {
|
|
let tcx = cx.tcx();
|
|
|
|
// Type-level uninhabitedness should always imply ABI uninhabitedness.
|
|
if layout.ty.is_privately_uninhabited(tcx, cx.param_env) {
|
|
assert!(layout.abi.is_uninhabited());
|
|
}
|
|
|
|
if layout.size.bytes() % layout.align.abi.bytes() != 0 {
|
|
bug!("size is not a multiple of align, in the following layout:\n{layout:#?}");
|
|
}
|
|
if layout.size.bytes() >= tcx.data_layout.obj_size_bound() {
|
|
bug!("size is too large, in the following layout:\n{layout:#?}");
|
|
}
|
|
|
|
if !cfg!(debug_assertions) {
|
|
// Stop here, the rest is kind of expensive.
|
|
return;
|
|
}
|
|
|
|
/// Yields non-ZST fields of the type
|
|
fn non_zst_fields<'tcx, 'a>(
|
|
cx: &'a LayoutCx<'tcx>,
|
|
layout: &'a TyAndLayout<'tcx>,
|
|
) -> impl Iterator<Item = (Size, TyAndLayout<'tcx>)> + 'a {
|
|
(0..layout.layout.fields().count()).filter_map(|i| {
|
|
let field = layout.field(cx, i);
|
|
// Also checking `align == 1` here leads to test failures in
|
|
// `layout/zero-sized-array-union.rs`, where a type has a zero-size field with
|
|
// alignment 4 that still gets ignored during layout computation (which is okay
|
|
// since other fields already force alignment 4).
|
|
let zst = field.is_zst();
|
|
(!zst).then(|| (layout.fields.offset(i), field))
|
|
})
|
|
}
|
|
|
|
fn skip_newtypes<'tcx>(cx: &LayoutCx<'tcx>, layout: &TyAndLayout<'tcx>) -> TyAndLayout<'tcx> {
|
|
if matches!(layout.layout.variants(), Variants::Multiple { .. }) {
|
|
// Definitely not a newtype of anything.
|
|
return *layout;
|
|
}
|
|
let mut fields = non_zst_fields(cx, layout);
|
|
let Some(first) = fields.next() else {
|
|
// No fields here, so this could be a primitive or enum -- either way it's not a newtype around a thing
|
|
return *layout;
|
|
};
|
|
if fields.next().is_none() {
|
|
let (offset, first) = first;
|
|
if offset == Size::ZERO && first.layout.size() == layout.size {
|
|
// This is a newtype, so keep recursing.
|
|
// FIXME(RalfJung): I don't think it would be correct to do any checks for
|
|
// alignment here, so we don't. Is that correct?
|
|
return skip_newtypes(cx, &first);
|
|
}
|
|
}
|
|
// No more newtypes here.
|
|
*layout
|
|
}
|
|
|
|
fn check_layout_abi<'tcx>(cx: &LayoutCx<'tcx>, layout: &TyAndLayout<'tcx>) {
|
|
// Verify the ABI mandated alignment and size.
|
|
let align = layout.abi.inherent_align(cx).map(|align| align.abi);
|
|
let size = layout.abi.inherent_size(cx);
|
|
let Some((align, size)) = align.zip(size) else {
|
|
assert_matches!(
|
|
layout.layout.abi(),
|
|
Abi::Uninhabited | Abi::Aggregate { .. },
|
|
"ABI unexpectedly missing alignment and/or size in {layout:#?}"
|
|
);
|
|
return;
|
|
};
|
|
assert_eq!(
|
|
layout.layout.align().abi,
|
|
align,
|
|
"alignment mismatch between ABI and layout in {layout:#?}"
|
|
);
|
|
assert_eq!(
|
|
layout.layout.size(),
|
|
size,
|
|
"size mismatch between ABI and layout in {layout:#?}"
|
|
);
|
|
|
|
// Verify per-ABI invariants
|
|
match layout.layout.abi() {
|
|
Abi::Scalar(_) => {
|
|
// Check that this matches the underlying field.
|
|
let inner = skip_newtypes(cx, layout);
|
|
assert!(
|
|
matches!(inner.layout.abi(), Abi::Scalar(_)),
|
|
"`Scalar` type {} is newtype around non-`Scalar` type {}",
|
|
layout.ty,
|
|
inner.ty
|
|
);
|
|
match inner.layout.fields() {
|
|
FieldsShape::Primitive => {
|
|
// Fine.
|
|
}
|
|
FieldsShape::Union(..) => {
|
|
// FIXME: I guess we could also check something here? Like, look at all fields?
|
|
return;
|
|
}
|
|
FieldsShape::Arbitrary { .. } => {
|
|
// Should be an enum, the only field is the discriminant.
|
|
assert!(
|
|
inner.ty.is_enum(),
|
|
"`Scalar` layout for non-primitive non-enum type {}",
|
|
inner.ty
|
|
);
|
|
assert_eq!(
|
|
inner.layout.fields().count(),
|
|
1,
|
|
"`Scalar` layout for multiple-field type in {inner:#?}",
|
|
);
|
|
let offset = inner.layout.fields().offset(0);
|
|
let field = inner.field(cx, 0);
|
|
// The field should be at the right offset, and match the `scalar` layout.
|
|
assert_eq!(
|
|
offset,
|
|
Size::ZERO,
|
|
"`Scalar` field at non-0 offset in {inner:#?}",
|
|
);
|
|
assert_eq!(field.size, size, "`Scalar` field with bad size in {inner:#?}",);
|
|
assert_eq!(
|
|
field.align.abi, align,
|
|
"`Scalar` field with bad align in {inner:#?}",
|
|
);
|
|
assert!(
|
|
matches!(field.abi, Abi::Scalar(_)),
|
|
"`Scalar` field with bad ABI in {inner:#?}",
|
|
);
|
|
}
|
|
_ => {
|
|
panic!("`Scalar` layout for non-primitive non-enum type {}", inner.ty);
|
|
}
|
|
}
|
|
}
|
|
Abi::ScalarPair(scalar1, scalar2) => {
|
|
// Check that the underlying pair of fields matches.
|
|
let inner = skip_newtypes(cx, layout);
|
|
assert!(
|
|
matches!(inner.layout.abi(), Abi::ScalarPair(..)),
|
|
"`ScalarPair` type {} is newtype around non-`ScalarPair` type {}",
|
|
layout.ty,
|
|
inner.ty
|
|
);
|
|
if matches!(inner.layout.variants(), Variants::Multiple { .. }) {
|
|
// FIXME: ScalarPair for enums is enormously complicated and it is very hard
|
|
// to check anything about them.
|
|
return;
|
|
}
|
|
match inner.layout.fields() {
|
|
FieldsShape::Arbitrary { .. } => {
|
|
// Checked below.
|
|
}
|
|
FieldsShape::Union(..) => {
|
|
// FIXME: I guess we could also check something here? Like, look at all fields?
|
|
return;
|
|
}
|
|
_ => {
|
|
panic!("`ScalarPair` layout with unexpected field shape in {inner:#?}");
|
|
}
|
|
}
|
|
let mut fields = non_zst_fields(cx, &inner);
|
|
let (offset1, field1) = fields.next().unwrap_or_else(|| {
|
|
panic!(
|
|
"`ScalarPair` layout for type with not even one non-ZST field: {inner:#?}"
|
|
)
|
|
});
|
|
let (offset2, field2) = fields.next().unwrap_or_else(|| {
|
|
panic!(
|
|
"`ScalarPair` layout for type with less than two non-ZST fields: {inner:#?}"
|
|
)
|
|
});
|
|
assert_matches!(
|
|
fields.next(),
|
|
None,
|
|
"`ScalarPair` layout for type with at least three non-ZST fields: {inner:#?}"
|
|
);
|
|
// The fields might be in opposite order.
|
|
let (offset1, field1, offset2, field2) = if offset1 <= offset2 {
|
|
(offset1, field1, offset2, field2)
|
|
} else {
|
|
(offset2, field2, offset1, field1)
|
|
};
|
|
// The fields should be at the right offset, and match the `scalar` layout.
|
|
let size1 = scalar1.size(cx);
|
|
let align1 = scalar1.align(cx).abi;
|
|
let size2 = scalar2.size(cx);
|
|
let align2 = scalar2.align(cx).abi;
|
|
assert_eq!(
|
|
offset1,
|
|
Size::ZERO,
|
|
"`ScalarPair` first field at non-0 offset in {inner:#?}",
|
|
);
|
|
assert_eq!(
|
|
field1.size, size1,
|
|
"`ScalarPair` first field with bad size in {inner:#?}",
|
|
);
|
|
assert_eq!(
|
|
field1.align.abi, align1,
|
|
"`ScalarPair` first field with bad align in {inner:#?}",
|
|
);
|
|
assert_matches!(
|
|
field1.abi,
|
|
Abi::Scalar(_),
|
|
"`ScalarPair` first field with bad ABI in {inner:#?}",
|
|
);
|
|
let field2_offset = size1.align_to(align2);
|
|
assert_eq!(
|
|
offset2, field2_offset,
|
|
"`ScalarPair` second field at bad offset in {inner:#?}",
|
|
);
|
|
assert_eq!(
|
|
field2.size, size2,
|
|
"`ScalarPair` second field with bad size in {inner:#?}",
|
|
);
|
|
assert_eq!(
|
|
field2.align.abi, align2,
|
|
"`ScalarPair` second field with bad align in {inner:#?}",
|
|
);
|
|
assert_matches!(
|
|
field2.abi,
|
|
Abi::Scalar(_),
|
|
"`ScalarPair` second field with bad ABI in {inner:#?}",
|
|
);
|
|
}
|
|
Abi::Vector { element, .. } => {
|
|
assert!(align >= element.align(cx).abi); // just sanity-checking `vector_align`.
|
|
// FIXME: Do some kind of check of the inner type, like for Scalar and ScalarPair.
|
|
}
|
|
Abi::Uninhabited | Abi::Aggregate { .. } => {} // Nothing to check.
|
|
}
|
|
}
|
|
|
|
check_layout_abi(cx, layout);
|
|
|
|
if let Variants::Multiple { variants, .. } = &layout.variants {
|
|
for variant in variants.iter() {
|
|
// No nested "multiple".
|
|
assert_matches!(variant.variants, Variants::Single { .. });
|
|
// Variants should have the same or a smaller size as the full thing,
|
|
// and same for alignment.
|
|
if variant.size > layout.size {
|
|
bug!(
|
|
"Type with size {} bytes has variant with size {} bytes: {layout:#?}",
|
|
layout.size.bytes(),
|
|
variant.size.bytes(),
|
|
)
|
|
}
|
|
if variant.align.abi > layout.align.abi {
|
|
bug!(
|
|
"Type with alignment {} bytes has variant with alignment {} bytes: {layout:#?}",
|
|
layout.align.abi.bytes(),
|
|
variant.align.abi.bytes(),
|
|
)
|
|
}
|
|
// Skip empty variants.
|
|
if variant.size == Size::ZERO
|
|
|| variant.fields.count() == 0
|
|
|| variant.abi.is_uninhabited()
|
|
{
|
|
// These are never actually accessed anyway, so we can skip the coherence check
|
|
// for them. They also fail that check, since they have
|
|
// `Aggregate`/`Uninhabited` ABI even when the main type is
|
|
// `Scalar`/`ScalarPair`. (Note that sometimes, variants with fields have size
|
|
// 0, and sometimes, variants without fields have non-0 size.)
|
|
continue;
|
|
}
|
|
// The top-level ABI and the ABI of the variants should be coherent.
|
|
let scalar_coherent =
|
|
|s1: Scalar, s2: Scalar| s1.size(cx) == s2.size(cx) && s1.align(cx) == s2.align(cx);
|
|
let abi_coherent = match (layout.abi, variant.abi) {
|
|
(Abi::Scalar(s1), Abi::Scalar(s2)) => scalar_coherent(s1, s2),
|
|
(Abi::ScalarPair(a1, b1), Abi::ScalarPair(a2, b2)) => {
|
|
scalar_coherent(a1, a2) && scalar_coherent(b1, b2)
|
|
}
|
|
(Abi::Uninhabited, _) => true,
|
|
(Abi::Aggregate { .. }, _) => true,
|
|
_ => false,
|
|
};
|
|
if !abi_coherent {
|
|
bug!(
|
|
"Variant ABI is incompatible with top-level ABI:\nvariant={:#?}\nTop-level: {layout:#?}",
|
|
variant
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|