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Auto merge of rust-lang#129949 - tgross35:rollup-352zljc, r=tgross35
Rollup of 8 pull requests Successful merges: - rust-lang#101339 (enable -Zrandomize-layout in debug CI builds ) - rust-lang#127021 (Add target support for RTEMS Arm) - rust-lang#128871 (bypass linker configuration and cross target check for specific commands) - rust-lang#129471 ([rustdoc] Sort impl associated items by kinds and then by appearance) - rust-lang#129529 (Add test to build crates used by r-a on stable) - rust-lang#129624 (Adjust `memchr` pinning and run `cargo update`) - rust-lang#129796 (Unify scraped examples with other code examples) - rust-lang#129939 (explain why Rvalue::Len still exists) r? `@ghost` `@rustbot` modify labels: rollup
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Cargo.lock

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compiler/rustc/Cargo.toml

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Original file line numberDiff line numberDiff line change
@@ -30,5 +30,6 @@ features = ['unprefixed_malloc_on_supported_platforms']
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jemalloc = ['dep:jemalloc-sys']
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llvm = ['rustc_driver_impl/llvm']
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max_level_info = ['rustc_driver_impl/max_level_info']
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rustc_randomized_layouts = ['rustc_driver_impl/rustc_randomized_layouts']
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rustc_use_parallel_compiler = ['rustc_driver_impl/rustc_use_parallel_compiler']
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# tidy-alphabetical-end

compiler/rustc_abi/src/layout.rs

Lines changed: 7 additions & 4 deletions
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@@ -968,8 +968,8 @@ fn univariant<
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let mut align = if pack.is_some() { dl.i8_align } else { dl.aggregate_align };
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let mut max_repr_align = repr.align;
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let mut inverse_memory_index: IndexVec<u32, FieldIdx> = fields.indices().collect();
971-
let optimize = !repr.inhibit_struct_field_reordering();
972-
if optimize && fields.len() > 1 {
971+
let optimize_field_order = !repr.inhibit_struct_field_reordering();
972+
if optimize_field_order && fields.len() > 1 {
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let end = if let StructKind::MaybeUnsized = kind { fields.len() - 1 } else { fields.len() };
974974
let optimizing = &mut inverse_memory_index.raw[..end];
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let fields_excluding_tail = &fields.raw[..end];
@@ -1176,7 +1176,7 @@ fn univariant<
11761176
// If field 5 has offset 0, offsets[0] is 5, and memory_index[5] should be 0.
11771177
// Field 5 would be the first element, so memory_index is i:
11781178
// Note: if we didn't optimize, it's already right.
1179-
let memory_index = if optimize {
1179+
let memory_index = if optimize_field_order {
11801180
inverse_memory_index.invert_bijective_mapping()
11811181
} else {
11821182
debug_assert!(inverse_memory_index.iter().copied().eq(fields.indices()));
@@ -1189,6 +1189,9 @@ fn univariant<
11891189
}
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let mut layout_of_single_non_zst_field = None;
11911191
let mut abi = Abi::Aggregate { sized };
1192+
1193+
let optimize_abi = !repr.inhibit_newtype_abi_optimization();
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// Try to make this a Scalar/ScalarPair.
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if sized && size.bytes() > 0 {
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// We skip *all* ZST here and later check if we are good in terms of alignment.
@@ -1205,7 +1208,7 @@ fn univariant<
12051208
match field.abi {
12061209
// For plain scalars, or vectors of them, we can't unpack
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// newtypes for `#[repr(C)]`, as that affects C ABIs.
1208-
Abi::Scalar(_) | Abi::Vector { .. } if optimize => {
1211+
Abi::Scalar(_) | Abi::Vector { .. } if optimize_abi => {
12091212
abi = field.abi;
12101213
}
12111214
// But scalar pairs are Rust-specific and get

compiler/rustc_abi/src/lib.rs

Lines changed: 11 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -43,14 +43,17 @@ bitflags! {
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const IS_SIMD = 1 << 1;
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const IS_TRANSPARENT = 1 << 2;
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// Internal only for now. If true, don't reorder fields.
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// On its own it does not prevent ABI optimizations.
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const IS_LINEAR = 1 << 3;
47-
// If true, the type's layout can be randomized using
48-
// the seed stored in `ReprOptions.field_shuffle_seed`
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// If true, the type's crate has opted into layout randomization.
49+
// Other flags can still inhibit reordering and thus randomization.
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// The seed stored in `ReprOptions.field_shuffle_seed`.
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const RANDOMIZE_LAYOUT = 1 << 4;
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// Any of these flags being set prevent field reordering optimisation.
51-
const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits()
53+
const FIELD_ORDER_UNOPTIMIZABLE = ReprFlags::IS_C.bits()
5254
| ReprFlags::IS_SIMD.bits()
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| ReprFlags::IS_LINEAR.bits();
56+
const ABI_UNOPTIMIZABLE = ReprFlags::IS_C.bits() | ReprFlags::IS_SIMD.bits();
5457
}
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}
5659

@@ -139,10 +142,14 @@ impl ReprOptions {
139142
self.c() || self.int.is_some()
140143
}
141144

145+
pub fn inhibit_newtype_abi_optimization(&self) -> bool {
146+
self.flags.intersects(ReprFlags::ABI_UNOPTIMIZABLE)
147+
}
148+
142149
/// Returns `true` if this `#[repr()]` guarantees a fixed field order,
143150
/// e.g. `repr(C)` or `repr(<int>)`.
144151
pub fn inhibit_struct_field_reordering(&self) -> bool {
145-
self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
152+
self.flags.intersects(ReprFlags::FIELD_ORDER_UNOPTIMIZABLE) || self.int.is_some()
146153
}
147154

148155
/// Returns `true` if this type is valid for reordering and `-Z randomize-layout`

compiler/rustc_ast/Cargo.toml

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -4,10 +4,9 @@ version = "0.0.0"
44
edition = "2021"
55

66
[dependencies]
7-
# FIXME: bumping memchr to 2.7.1 causes linker errors in MSVC thin-lto
87
# tidy-alphabetical-start
98
bitflags = "2.4.1"
10-
memchr = "=2.5.0"
9+
memchr = "2.7.4"
1110
rustc_ast_ir = { path = "../rustc_ast_ir" }
1211
rustc_data_structures = { path = "../rustc_data_structures" }
1312
rustc_index = { path = "../rustc_index" }

compiler/rustc_driver_impl/Cargo.toml

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@@ -23,6 +23,7 @@ rustc_hir_analysis = { path = "../rustc_hir_analysis" }
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rustc_hir_pretty = { path = "../rustc_hir_pretty" }
2424
rustc_hir_typeck = { path = "../rustc_hir_typeck" }
2525
rustc_incremental = { path = "../rustc_incremental" }
26+
rustc_index = { path = "../rustc_index" }
2627
rustc_infer = { path = "../rustc_infer" }
2728
rustc_interface = { path = "../rustc_interface" }
2829
rustc_lint = { path = "../rustc_lint" }
@@ -72,6 +73,10 @@ ctrlc = "3.4.4"
7273
# tidy-alphabetical-start
7374
llvm = ['rustc_interface/llvm']
7475
max_level_info = ['rustc_log/max_level_info']
76+
rustc_randomized_layouts = [
77+
'rustc_index/rustc_randomized_layouts',
78+
'rustc_middle/rustc_randomized_layouts'
79+
]
7580
rustc_use_parallel_compiler = [
7681
'rustc_data_structures/rustc_use_parallel_compiler',
7782
'rustc_interface/rustc_use_parallel_compiler',

compiler/rustc_index/Cargo.toml

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@@ -20,4 +20,5 @@ nightly = [
2020
"dep:rustc_macros",
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"rustc_index_macros/nightly",
2222
]
23+
rustc_randomized_layouts = []
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# tidy-alphabetical-end

compiler/rustc_index/src/lib.rs

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@@ -33,8 +33,19 @@ pub use vec::IndexVec;
3333
///
3434
/// </div>
3535
#[macro_export]
36+
#[cfg(not(feature = "rustc_randomized_layouts"))]
3637
macro_rules! static_assert_size {
3738
($ty:ty, $size:expr) => {
3839
const _: [(); $size] = [(); ::std::mem::size_of::<$ty>()];
3940
};
4041
}
42+
43+
#[macro_export]
44+
#[cfg(feature = "rustc_randomized_layouts")]
45+
macro_rules! static_assert_size {
46+
($ty:ty, $size:expr) => {
47+
// no effect other than using the statements.
48+
// struct sizes are not deterministic under randomized layouts
49+
const _: (usize, usize) = ($size, ::std::mem::size_of::<$ty>());
50+
};
51+
}

compiler/rustc_middle/Cargo.toml

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Original file line numberDiff line numberDiff line change
@@ -40,5 +40,6 @@ tracing = "0.1"
4040

4141
[features]
4242
# tidy-alphabetical-start
43+
rustc_randomized_layouts = []
4344
rustc_use_parallel_compiler = ["dep:rustc-rayon-core"]
4445
# tidy-alphabetical-end

compiler/rustc_middle/src/mir/syntax.rs

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@@ -1307,6 +1307,9 @@ pub enum Rvalue<'tcx> {
13071307
/// If the type of the place is an array, this is the array length. For slices (`[T]`, not
13081308
/// `&[T]`) this accesses the place's metadata to determine the length. This rvalue is
13091309
/// ill-formed for places of other types.
1310+
///
1311+
/// This cannot be a `UnOp(PtrMetadata, _)` because that expects a value, and we only
1312+
/// have a place, and `UnOp(PtrMetadata, RawPtr(place))` is not a thing.
13101313
Len(Place<'tcx>),
13111314

13121315
/// Performs essentially all of the casts that can be performed via `as`.

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