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luqmanaluqmana
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Factor out checks in layout check and add helper inherent_size.
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3 files changed

+63
-55
lines changed

3 files changed

+63
-55
lines changed

‎compiler/rustc_abi/src/lib.rs

+22-1
Original file line numberDiff line numberDiff line change
@@ -1273,7 +1273,7 @@ impl Abi {
12731273
matches!(*self, Abi::Scalar(_))
12741274
}
12751275

1276-
/// Returns the fixed alignment of this ABI, if any
1276+
/// Returns the fixed alignment of this ABI, if any is mandated.
12771277
pub fn inherent_align<C: HasDataLayout>(&self, cx: &C) -> Option<AbiAndPrefAlign> {
12781278
Some(match *self {
12791279
Abi::Scalar(s) => s.align(cx),
@@ -1287,6 +1287,27 @@ impl Abi {
12871287
})
12881288
}
12891289

1290+
/// Returns the fixed size of this ABI, if any is mandated.
1291+
pub fn inherent_size<C: HasDataLayout>(&self, cx: &C) -> Option<Size> {
1292+
Some(match *self {
1293+
Abi::Scalar(s) => {
1294+
// No padding in scalars.
1295+
s.size(cx)
1296+
}
1297+
Abi::ScalarPair(s1, s2) => {
1298+
// May have some padding between the pair.
1299+
let field2_offset = s1.size(cx).align_to(s2.align(cx).abi);
1300+
(field2_offset + s2.size(cx)).align_to(self.inherent_align(cx)?.abi)
1301+
}
1302+
Abi::Vector { element, count } => {
1303+
// No padding in vectors, except possibly for trailing padding
1304+
// to make the size a multiple of align (e.g. for vectors of size 3).
1305+
(element.size(cx) * count).align_to(self.inherent_align(cx)?.abi)
1306+
}
1307+
Abi::Uninhabited | Abi::Aggregate { .. } => return None,
1308+
})
1309+
}
1310+
12901311
/// Discard valid range information and allow undef
12911312
pub fn to_union(&self) -> Self {
12921313
assert!(self.is_sized());

‎compiler/rustc_ty_utils/src/layout_sanity_check.rs

+40-54
Original file line numberDiff line numberDiff line change
@@ -4,7 +4,7 @@ use rustc_middle::ty::{
44
};
55
use rustc_target::abi::*;
66

7-
use std::cmp;
7+
use std::assert_matches::assert_matches;
88

99
/// Enforce some basic invariants on layouts.
1010
pub(super) fn sanity_check_layout<'tcx>(
@@ -68,21 +68,31 @@ pub(super) fn sanity_check_layout<'tcx>(
6868
}
6969

7070
fn check_layout_abi<'tcx>(cx: &LayoutCx<'tcx, TyCtxt<'tcx>>, layout: &TyAndLayout<'tcx>) {
71+
// Verify the ABI mandated alignment and size.
72+
let align = layout.abi.inherent_align(cx).map(|align| align.abi);
73+
let size = layout.abi.inherent_size(cx);
74+
let Some((align, size)) = align.zip(size) else {
75+
assert_matches!(
76+
layout.layout.abi(),
77+
Abi::Uninhabited | Abi::Aggregate { .. },
78+
"ABI unexpectedly missing alignment and/or size in {layout:#?}"
79+
);
80+
return
81+
};
82+
assert_eq!(
83+
layout.layout.align().abi,
84+
align,
85+
"alignment mismatch between ABI and layout in {layout:#?}"
86+
);
87+
assert_eq!(
88+
layout.layout.size(),
89+
size,
90+
"size mismatch between ABI and layout in {layout:#?}"
91+
);
92+
93+
// Verify per-ABI invariants
7194
match layout.layout.abi() {
72-
Abi::Scalar(scalar) => {
73-
// No padding in scalars.
74-
let size = scalar.size(cx);
75-
let align = scalar.align(cx).abi;
76-
assert_eq!(
77-
layout.layout.size(),
78-
size,
79-
"size mismatch between ABI and layout in {layout:#?}"
80-
);
81-
assert_eq!(
82-
layout.layout.align().abi,
83-
align,
84-
"alignment mismatch between ABI and layout in {layout:#?}"
85-
);
95+
Abi::Scalar(_) => {
8696
// Check that this matches the underlying field.
8797
let inner = skip_newtypes(cx, layout);
8898
assert!(
@@ -135,24 +145,6 @@ pub(super) fn sanity_check_layout<'tcx>(
135145
}
136146
}
137147
Abi::ScalarPair(scalar1, scalar2) => {
138-
// Sanity-check scalar pairs. Computing the expected size and alignment is a bit of work.
139-
let size1 = scalar1.size(cx);
140-
let align1 = scalar1.align(cx).abi;
141-
let size2 = scalar2.size(cx);
142-
let align2 = scalar2.align(cx).abi;
143-
let align = cmp::max(align1, align2);
144-
let field2_offset = size1.align_to(align2);
145-
let size = (field2_offset + size2).align_to(align);
146-
assert_eq!(
147-
layout.layout.size(),
148-
size,
149-
"size mismatch between ABI and layout in {layout:#?}"
150-
);
151-
assert_eq!(
152-
layout.layout.align().abi,
153-
align,
154-
"alignment mismatch between ABI and layout in {layout:#?}",
155-
);
156148
// Check that the underlying pair of fields matches.
157149
let inner = skip_newtypes(cx, layout);
158150
assert!(
@@ -189,8 +181,9 @@ pub(super) fn sanity_check_layout<'tcx>(
189181
"`ScalarPair` layout for type with less than two non-ZST fields: {inner:#?}"
190182
)
191183
});
192-
assert!(
193-
fields.next().is_none(),
184+
assert_matches!(
185+
fields.next(),
186+
None,
194187
"`ScalarPair` layout for type with at least three non-ZST fields: {inner:#?}"
195188
);
196189
// The fields might be in opposite order.
@@ -200,6 +193,10 @@ pub(super) fn sanity_check_layout<'tcx>(
200193
(offset2, field2, offset1, field1)
201194
};
202195
// The fields should be at the right offset, and match the `scalar` layout.
196+
let size1 = scalar1.size(cx);
197+
let align1 = scalar1.align(cx).abi;
198+
let size2 = scalar2.size(cx);
199+
let align2 = scalar2.align(cx).abi;
203200
assert_eq!(
204201
offset1,
205202
Size::ZERO,
@@ -213,10 +210,12 @@ pub(super) fn sanity_check_layout<'tcx>(
213210
field1.align.abi, align1,
214211
"`ScalarPair` first field with bad align in {inner:#?}",
215212
);
216-
assert!(
217-
matches!(field1.abi, Abi::Scalar(_)),
213+
assert_matches!(
214+
field1.abi,
215+
Abi::Scalar(_),
218216
"`ScalarPair` first field with bad ABI in {inner:#?}",
219217
);
218+
let field2_offset = size1.align_to(align2);
220219
assert_eq!(
221220
offset2, field2_offset,
222221
"`ScalarPair` second field at bad offset in {inner:#?}",
@@ -229,27 +228,14 @@ pub(super) fn sanity_check_layout<'tcx>(
229228
field2.align.abi, align2,
230229
"`ScalarPair` second field with bad align in {inner:#?}",
231230
);
232-
assert!(
233-
matches!(field2.abi, Abi::Scalar(_)),
231+
assert_matches!(
232+
field2.abi,
233+
Abi::Scalar(_),
234234
"`ScalarPair` second field with bad ABI in {inner:#?}",
235235
);
236236
}
237-
Abi::Vector { count, element } => {
238-
// No padding in vectors, except possibly for trailing padding to make the size a multiple of align.
239-
let size = element.size(cx) * count;
240-
let align = cx.data_layout().vector_align(size).abi;
241-
let size = size.align_to(align); // needed e.g. for vectors of size 3
237+
Abi::Vector { element, .. } => {
242238
assert!(align >= element.align(cx).abi); // just sanity-checking `vector_align`.
243-
assert_eq!(
244-
layout.layout.size(),
245-
size,
246-
"size mismatch between ABI and layout in {layout:#?}"
247-
);
248-
assert_eq!(
249-
layout.layout.align().abi,
250-
align,
251-
"alignment mismatch between ABI and layout in {layout:#?}"
252-
);
253239
// FIXME: Do some kind of check of the inner type, like for Scalar and ScalarPair.
254240
}
255241
Abi::Uninhabited | Abi::Aggregate { .. } => {} // Nothing to check.

‎compiler/rustc_ty_utils/src/lib.rs

+1
Original file line numberDiff line numberDiff line change
@@ -5,6 +5,7 @@
55
//! This API is completely unstable and subject to change.
66
77
#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
8+
#![feature(assert_matches)]
89
#![feature(iterator_try_collect)]
910
#![feature(let_chains)]
1011
#![feature(never_type)]

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