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scottmcmscottmcm
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Add an intrinsic that lowers to AggregateKind::RawPtr
1 parent e6b2b76 commit 4f44426

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8 files changed

+264
-1
lines changed

8 files changed

+264
-1
lines changed

‎compiler/rustc_const_eval/src/transform/validate.rs

+4-1
Original file line numberDiff line numberDiff line change
@@ -946,7 +946,10 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
946946
self.fail(location, "input pointer must be thin");
947947
}
948948
} else {
949-
self.fail(location, "first operand to raw pointer aggregate must be a raw pointer");
949+
self.fail(
950+
location,
951+
"first operand to raw pointer aggregate must be a raw pointer",
952+
);
950953
}
951954

952955
// FIXME: Check metadata more generally

‎compiler/rustc_hir_analysis/src/check/intrinsic.rs

+5
Original file line numberDiff line numberDiff line change
@@ -128,6 +128,7 @@ pub fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: LocalDefId) -
128128
| sym::variant_count
129129
| sym::is_val_statically_known
130130
| sym::ptr_mask
131+
| sym::aggregate_raw_ptr
131132
| sym::ub_checks
132133
| sym::fadd_algebraic
133134
| sym::fsub_algebraic
@@ -574,6 +575,10 @@ pub fn check_intrinsic_type(
574575
(0, 0, vec![Ty::new_imm_ptr(tcx, Ty::new_unit(tcx))], tcx.types.usize)
575576
}
576577

578+
// This type check is not particularly useful, but the `where` bounds
579+
// on the definition in `core` do the heavy lifting for checking it.
580+
sym::aggregate_raw_ptr => (3, 1, vec![param(1), param(2)], param(0)),
581+
577582
sym::ub_checks => (0, 1, Vec::new(), tcx.types.bool),
578583

579584
sym::simd_eq

‎compiler/rustc_mir_transform/src/lower_intrinsics.rs

+28
Original file line numberDiff line numberDiff line change
@@ -287,6 +287,34 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
287287
terminator.kind = TerminatorKind::Unreachable;
288288
}
289289
}
290+
sym::aggregate_raw_ptr => {
291+
let Ok([data, meta]) = <[_; 2]>::try_from(std::mem::take(args)) else {
292+
span_bug!(
293+
terminator.source_info.span,
294+
"Wrong number of arguments for aggregate_raw_ptr intrinsic",
295+
);
296+
};
297+
let target = target.unwrap();
298+
let pointer_ty = generic_args.type_at(0);
299+
let kind = if let ty::RawPtr(pointee_ty, mutability) = pointer_ty.kind() {
300+
AggregateKind::RawPtr(*pointee_ty, *mutability)
301+
} else {
302+
span_bug!(
303+
terminator.source_info.span,
304+
"Return type of aggregate_raw_ptr intrinsic must be a raw pointer",
305+
);
306+
};
307+
let fields = [data.node, meta.node];
308+
block.statements.push(Statement {
309+
source_info: terminator.source_info,
310+
kind: StatementKind::Assign(Box::new((
311+
*destination,
312+
Rvalue::Aggregate(Box::new(kind), fields.into()),
313+
))),
314+
});
315+
316+
terminator.kind = TerminatorKind::Goto { target };
317+
}
290318
_ => {}
291319
}
292320
}

‎compiler/rustc_span/src/symbol.rs

+1
Original file line numberDiff line numberDiff line change
@@ -361,6 +361,7 @@ symbols! {
361361
adt_const_params,
362362
advanced_slice_patterns,
363363
adx_target_feature,
364+
aggregate_raw_ptr,
364365
alias,
365366
align,
366367
align_offset,

‎library/core/src/intrinsics.rs

+26
Original file line numberDiff line numberDiff line change
@@ -2779,6 +2779,32 @@ pub unsafe fn vtable_align(_ptr: *const ()) -> usize {
27792779
unreachable!()
27802780
}
27812781

2782+
/// Lowers in MIR to `Rvalue::Aggregate` with `AggregateKind::RawPtr`.
2783+
///
2784+
/// This is used to implement functions like `slice::from_raw_parts_mut` and
2785+
/// `ptr::from_raw_parts` in a way compatible with the compiler being able to
2786+
/// change the possible layouts of pointers.
2787+
#[rustc_nounwind]
2788+
#[unstable(feature = "core_intrinsics", issue = "none")]
2789+
#[rustc_intrinsic]
2790+
#[rustc_intrinsic_must_be_overridden]
2791+
#[cfg(not(bootstrap))]
2792+
pub const fn aggregate_raw_ptr<P: AggregateRawPtr<D, Metadata = M>, D, M>(_data: D, _meta: M) -> P {
2793+
// No fallback because `libcore` doesn't want to know the layout
2794+
unreachable!()
2795+
}
2796+
2797+
#[unstable(feature = "core_intrinsics", issue = "none")]
2798+
pub trait AggregateRawPtr<D> {
2799+
type Metadata: Copy;
2800+
}
2801+
impl<P: ?Sized, T: ptr::Thin> AggregateRawPtr<*const T> for *const P {
2802+
type Metadata = <P as ptr::Pointee>::Metadata;
2803+
}
2804+
impl<P: ?Sized, T: ptr::Thin> AggregateRawPtr<*mut T> for *mut P {
2805+
type Metadata = <P as ptr::Pointee>::Metadata;
2806+
}
2807+
27822808
// Some functions are defined here because they accidentally got made
27832809
// available in this module on stable. See <https://github.com/rust-lang/rust/issues/15702>.
27842810
// (`transmute` also falls into this category, but it cannot be wrapped due to the

‎tests/mir-opt/lower_intrinsics.make_pointers.LowerIntrinsics.panic-abort.diff

+95
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,95 @@
1+
- // MIR for `make_pointers` before LowerIntrinsics
2+
+ // MIR for `make_pointers` after LowerIntrinsics
3+
4+
fn make_pointers(_1: *const u8, _2: *mut (), _3: usize) -> () {
5+
debug a => _1;
6+
debug b => _2;
7+
debug n => _3;
8+
let mut _0: ();
9+
let _4: *const i32;
10+
let mut _5: *const u8;
11+
let mut _6: ();
12+
let mut _8: *mut ();
13+
let mut _9: ();
14+
let mut _11: *const u8;
15+
let mut _12: usize;
16+
let mut _14: *mut ();
17+
let mut _15: usize;
18+
scope 1 {
19+
debug _thin_const => _4;
20+
let _7: *mut u8;
21+
scope 2 {
22+
debug _thin_mut => _7;
23+
let _10: *const [u16];
24+
scope 3 {
25+
debug _slice_const => _10;
26+
let _13: *mut [u64];
27+
scope 4 {
28+
debug _slice_mut => _13;
29+
}
30+
}
31+
}
32+
}
33+
34+
bb0: {
35+
StorageLive(_4);
36+
StorageLive(_5);
37+
_5 = _1;
38+
StorageLive(_6);
39+
_6 = ();
40+
- _4 = aggregate_raw_ptr::<*const i32, *const u8, ()>(move _5, move _6) -> [return: bb1, unwind unreachable];
41+
+ _4 = *const i32 from (move _5, move _6);
42+
+ goto -> bb1;
43+
}
44+
45+
bb1: {
46+
StorageDead(_6);
47+
StorageDead(_5);
48+
StorageLive(_7);
49+
StorageLive(_8);
50+
_8 = _2;
51+
StorageLive(_9);
52+
_9 = ();
53+
- _7 = aggregate_raw_ptr::<*mut u8, *mut (), ()>(move _8, move _9) -> [return: bb2, unwind unreachable];
54+
+ _7 = *mut u8 from (move _8, move _9);
55+
+ goto -> bb2;
56+
}
57+
58+
bb2: {
59+
StorageDead(_9);
60+
StorageDead(_8);
61+
StorageLive(_10);
62+
StorageLive(_11);
63+
_11 = _1;
64+
StorageLive(_12);
65+
_12 = _3;
66+
- _10 = aggregate_raw_ptr::<*const [u16], *const u8, usize>(move _11, move _12) -> [return: bb3, unwind unreachable];
67+
+ _10 = *const [u16] from (move _11, move _12);
68+
+ goto -> bb3;
69+
}
70+
71+
bb3: {
72+
StorageDead(_12);
73+
StorageDead(_11);
74+
StorageLive(_13);
75+
StorageLive(_14);
76+
_14 = _2;
77+
StorageLive(_15);
78+
_15 = _3;
79+
- _13 = aggregate_raw_ptr::<*mut [u64], *mut (), usize>(move _14, move _15) -> [return: bb4, unwind unreachable];
80+
+ _13 = *mut [u64] from (move _14, move _15);
81+
+ goto -> bb4;
82+
}
83+
84+
bb4: {
85+
StorageDead(_15);
86+
StorageDead(_14);
87+
_0 = const ();
88+
StorageDead(_13);
89+
StorageDead(_10);
90+
StorageDead(_7);
91+
StorageDead(_4);
92+
return;
93+
}
94+
}
95+

‎tests/mir-opt/lower_intrinsics.make_pointers.LowerIntrinsics.panic-unwind.diff

+95
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,95 @@
1+
- // MIR for `make_pointers` before LowerIntrinsics
2+
+ // MIR for `make_pointers` after LowerIntrinsics
3+
4+
fn make_pointers(_1: *const u8, _2: *mut (), _3: usize) -> () {
5+
debug a => _1;
6+
debug b => _2;
7+
debug n => _3;
8+
let mut _0: ();
9+
let _4: *const i32;
10+
let mut _5: *const u8;
11+
let mut _6: ();
12+
let mut _8: *mut ();
13+
let mut _9: ();
14+
let mut _11: *const u8;
15+
let mut _12: usize;
16+
let mut _14: *mut ();
17+
let mut _15: usize;
18+
scope 1 {
19+
debug _thin_const => _4;
20+
let _7: *mut u8;
21+
scope 2 {
22+
debug _thin_mut => _7;
23+
let _10: *const [u16];
24+
scope 3 {
25+
debug _slice_const => _10;
26+
let _13: *mut [u64];
27+
scope 4 {
28+
debug _slice_mut => _13;
29+
}
30+
}
31+
}
32+
}
33+
34+
bb0: {
35+
StorageLive(_4);
36+
StorageLive(_5);
37+
_5 = _1;
38+
StorageLive(_6);
39+
_6 = ();
40+
- _4 = aggregate_raw_ptr::<*const i32, *const u8, ()>(move _5, move _6) -> [return: bb1, unwind unreachable];
41+
+ _4 = *const i32 from (move _5, move _6);
42+
+ goto -> bb1;
43+
}
44+
45+
bb1: {
46+
StorageDead(_6);
47+
StorageDead(_5);
48+
StorageLive(_7);
49+
StorageLive(_8);
50+
_8 = _2;
51+
StorageLive(_9);
52+
_9 = ();
53+
- _7 = aggregate_raw_ptr::<*mut u8, *mut (), ()>(move _8, move _9) -> [return: bb2, unwind unreachable];
54+
+ _7 = *mut u8 from (move _8, move _9);
55+
+ goto -> bb2;
56+
}
57+
58+
bb2: {
59+
StorageDead(_9);
60+
StorageDead(_8);
61+
StorageLive(_10);
62+
StorageLive(_11);
63+
_11 = _1;
64+
StorageLive(_12);
65+
_12 = _3;
66+
- _10 = aggregate_raw_ptr::<*const [u16], *const u8, usize>(move _11, move _12) -> [return: bb3, unwind unreachable];
67+
+ _10 = *const [u16] from (move _11, move _12);
68+
+ goto -> bb3;
69+
}
70+
71+
bb3: {
72+
StorageDead(_12);
73+
StorageDead(_11);
74+
StorageLive(_13);
75+
StorageLive(_14);
76+
_14 = _2;
77+
StorageLive(_15);
78+
_15 = _3;
79+
- _13 = aggregate_raw_ptr::<*mut [u64], *mut (), usize>(move _14, move _15) -> [return: bb4, unwind unreachable];
80+
+ _13 = *mut [u64] from (move _14, move _15);
81+
+ goto -> bb4;
82+
}
83+
84+
bb4: {
85+
StorageDead(_15);
86+
StorageDead(_14);
87+
_0 = const ();
88+
StorageDead(_13);
89+
StorageDead(_10);
90+
StorageDead(_7);
91+
StorageDead(_4);
92+
return;
93+
}
94+
}
95+

‎tests/mir-opt/lower_intrinsics.rs

+10
Original file line numberDiff line numberDiff line change
@@ -248,3 +248,13 @@ pub fn three_way_compare_signed(a: i16, b: i16) {
248248
pub fn three_way_compare_unsigned(a: u32, b: u32) {
249249
let _x = core::intrinsics::three_way_compare(a, b);
250250
}
251+
252+
// EMIT_MIR lower_intrinsics.make_pointers.LowerIntrinsics.diff
253+
pub fn make_pointers(a: *const u8, b: *mut (), n: usize) {
254+
use std::intrinsics::aggregate_raw_ptr;
255+
256+
let _thin_const: *const i32 = aggregate_raw_ptr(a, ());
257+
let _thin_mut: *mut u8 = aggregate_raw_ptr(b, ());
258+
let _slice_const: *const [u16] = aggregate_raw_ptr(a, n);
259+
let _slice_mut: *mut [u64] = aggregate_raw_ptr(b, n);
260+
}

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