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Rollup merge of #96872 - RalfJung:layout-sanity, r=eddyb

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make sure ScalarPair enums have ScalarPair variants; add some layout sanity checks

`@eddyb` suggested that it might be reasonable for `ScalarPair` enums to simply adjust the ABI of their variants accordingly, such that the layout invariant Miri expects actually holds. This PR implements that. I should note though that I don't know much about this layout computation code and what non-Miri consumers expect from it, so tread with caution!

I also added a function to sanity-check that computed layouts are internally consistent. This helped a lot in figuring out the final shape of this PR, though I am also not 100% sure that these sanity checks are the right ones.

Cc `@oli-obk`
Fixes https://github.com/rust-lang/rust/issues/96221
This commit is contained in:
Dylan DPC 2022-05-10 08:24:05 +02:00 • committed by GitHub
commit ec53c379cc
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4 changed files with 237 additions and 31 deletions
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2
src/test/codegen/align-struct.rs
View file

@ -19,7 +19,7 @@ pub enum Enum4 {
A(i32),
B(i32),
}
// CHECK: %"Enum4::A" = type { [1 x i32], i32 }
// No Aggregate type, and hence nothing in LLVM IR.
pub enum Enum64 {
A(Align64),

38
src/test/ui/layout/debug.stderr
View file

@ -184,9 +184,22 @@ error: layout_of(std::result::Result<i32, i32>) = Layout {
variants: Single {
index: 0,
},
abi: Aggregate {
sized: true,
},
abi: ScalarPair(
Initialized {
value: Int(
I32,
false,
),
valid_range: 0..=1,
},
Initialized {
value: Int(
I32,
true,
),
valid_range: 0..=4294967295,
},
),
largest_niche: None,
align: AbiAndPrefAlign {
abi: Align(4 bytes),
@ -206,9 +219,22 @@ error: layout_of(std::result::Result<i32, i32>) = Layout {
variants: Single {
index: 1,
},
abi: Aggregate {
sized: true,
},
abi: ScalarPair(
Initialized {
value: Int(
I32,
false,
),
valid_range: 0..=1,
},
Initialized {
value: Int(
I32,
true,
),
valid_range: 0..=4294967295,
},
),
largest_niche: None,
align: AbiAndPrefAlign {
abi: Align(4 bytes),

92
src/test/ui/layout/issue-96158-scalarpair-payload-might-be-uninit.stderr
View file

@ -30,9 +30,21 @@ error: layout_of(MissingPayloadField) = Layout {
variants: Single {
index: 0,
},
abi: Aggregate {
sized: true,
},
abi: ScalarPair(
Initialized {
value: Int(
I8,
false,
),
valid_range: 0..=1,
},
Union {
value: Int(
I8,
false,
),
},
),
largest_niche: None,
align: AbiAndPrefAlign {
abi: Align(1 bytes),
@ -131,9 +143,22 @@ error: layout_of(CommonPayloadField) = Layout {
variants: Single {
index: 0,
},
abi: Aggregate {
sized: true,
},
abi: ScalarPair(
Initialized {
value: Int(
I8,
false,
),
valid_range: 0..=1,
},
Initialized {
value: Int(
I8,
false,
),
valid_range: 0..=255,
},
),
largest_niche: None,
align: AbiAndPrefAlign {
abi: Align(1 bytes),
@ -153,9 +178,22 @@ error: layout_of(CommonPayloadField) = Layout {
variants: Single {
index: 1,
},
abi: Aggregate {
sized: true,
},
abi: ScalarPair(
Initialized {
value: Int(
I8,
false,
),
valid_range: 0..=1,
},
Initialized {
value: Int(
I8,
false,
),
valid_range: 0..=255,
},
),
largest_niche: None,
align: AbiAndPrefAlign {
abi: Align(1 bytes),
@ -237,9 +275,21 @@ error: layout_of(CommonPayloadFieldIsMaybeUninit) = Layout {
variants: Single {
index: 0,
},
abi: Aggregate {
sized: true,
},
abi: ScalarPair(
Initialized {
value: Int(
I8,
false,
),
valid_range: 0..=1,
},
Union {
value: Int(
I8,
false,
),
},
),
largest_niche: None,
align: AbiAndPrefAlign {
abi: Align(1 bytes),
@ -259,9 +309,21 @@ error: layout_of(CommonPayloadFieldIsMaybeUninit) = Layout {
variants: Single {
index: 1,
},
abi: Aggregate {
sized: true,
},
abi: ScalarPair(
Initialized {
value: Int(
I8,
false,
),
valid_range: 0..=1,
},
Union {
value: Int(
I8,
false,
),
},
),
largest_niche: None,
align: AbiAndPrefAlign {
abi: Align(1 bytes),