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scottmcmscottmcm
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Use it in the library, and InstSimplify it away in the easy places
1 parent 4f44426 commit de64ff7

11 files changed

+328
-28
lines changed

‎compiler/rustc_codegen_ssa/src/mir/rvalue.rs

+21-1
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@ use crate::MemFlags;
99

1010
use rustc_hir as hir;
1111
use rustc_middle::mir;
12-
use rustc_middle::mir::Operand;
12+
use rustc_middle::mir::{AggregateKind, Operand};
1313
use rustc_middle::ty::cast::{CastTy, IntTy};
1414
use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, TyAndLayout};
1515
use rustc_middle::ty::{self, adjustment::PointerCoercion, Instance, Ty, TyCtxt};
@@ -720,6 +720,24 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
720720
OperandRef { val: OperandValue::Immediate(static_), layout }
721721
}
722722
mir::Rvalue::Use(ref operand) => self.codegen_operand(bx, operand),
723+
mir::Rvalue::Aggregate(box mir::AggregateKind::RawPtr(..), ref fields) => {
724+
let ty = rvalue.ty(self.mir, self.cx.tcx());
725+
let layout = self.cx.layout_of(self.monomorphize(ty));
726+
let [data, meta] = &*fields.raw else {
727+
bug!("RawPtr fields: {fields:?}");
728+
};
729+
let data = self.codegen_operand(bx, data);
730+
let meta = self.codegen_operand(bx, meta);
731+
match (data.val, meta.val) {
732+
(p @ OperandValue::Immediate(_), OperandValue::ZeroSized) => {
733+
OperandRef { val: p, layout }
734+
}
735+
(OperandValue::Immediate(p), OperandValue::Immediate(m)) => {
736+
OperandRef { val: OperandValue::Pair(p, m), layout }
737+
}
738+
_ => bug!("RawPtr operands {data:?} {meta:?}"),
739+
}
740+
}
723741
mir::Rvalue::Repeat(..) | mir::Rvalue::Aggregate(..) => {
724742
// According to `rvalue_creates_operand`, only ZST
725743
// aggregate rvalues are allowed to be operands.
@@ -1032,6 +1050,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
10321050
mir::Rvalue::ThreadLocalRef(_) |
10331051
mir::Rvalue::Use(..) => // (*)
10341052
true,
1053+
// This always produces a `ty::RawPtr`, so will be Immediate or Pair
1054+
mir::Rvalue::Aggregate(box AggregateKind::RawPtr(..), ..) => true,
10351055
mir::Rvalue::Repeat(..) |
10361056
mir::Rvalue::Aggregate(..) => {
10371057
let ty = rvalue.ty(self.mir, self.cx.tcx());

‎compiler/rustc_const_eval/src/interpret/operand.rs

+11
Original file line numberDiff line numberDiff line change
@@ -603,6 +603,17 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
603603
Ok(self.read_immediate(op)?.to_scalar())
604604
}
605605

606+
pub fn read_mem_place_meta(
607+
&self,
608+
op: &impl Readable<'tcx, M::Provenance>,
609+
) -> InterpResult<'tcx, MemPlaceMeta<M::Provenance>> {
610+
Ok(if op.layout().is_zst() {
611+
MemPlaceMeta::None
612+
} else {
613+
MemPlaceMeta::Meta(self.read_scalar(op)?)
614+
})
615+
}
616+
606617
// Pointer-sized reads are fairly common and need target layout access, so we wrap them in
607618
// convenience functions.
608619

‎compiler/rustc_const_eval/src/interpret/step.rs

+16-1
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@ use rustc_middle::mir;
99
use rustc_middle::ty::layout::LayoutOf;
1010
use rustc_target::abi::{FieldIdx, FIRST_VARIANT};
1111

12-
use super::{ImmTy, InterpCx, InterpResult, Machine, PlaceTy, Projectable, Scalar};
12+
use super::{ImmTy, Immediate, InterpCx, InterpResult, Machine, PlaceTy, Projectable, Scalar};
1313
use crate::util;
1414

1515
impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
@@ -303,6 +303,21 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
303303
let variant_dest = self.project_downcast(dest, variant_index)?;
304304
(variant_index, variant_dest, active_field_index)
305305
}
306+
mir::AggregateKind::RawPtr(..) => {
307+
// Trying to `project_field` into pointers tends not to work,
308+
// so build the `Immediate` from the parts directly.
309+
let [data, meta] = &operands.raw else {
310+
bug!("{kind:?} should have 2 operands, had {operands:?}");
311+
};
312+
let data = self.eval_operand(data, None)?;
313+
let data = self.read_pointer(&data)?;
314+
let meta = self.eval_operand(meta, None)?;
315+
let meta = self.read_mem_place_meta(&meta)?;
316+
let ptr_imm = Immediate::new_pointer_with_meta(data, meta, self);
317+
let ptr = ImmTy::from_immediate(ptr_imm, dest.layout);
318+
self.copy_op(&ptr, dest)?;
319+
return Ok(());
320+
}
306321
_ => (FIRST_VARIANT, dest.clone(), None),
307322
};
308323
if active_field_index.is_some() {

‎library/core/src/intrinsics.rs

+1
Original file line numberDiff line numberDiff line change
@@ -2786,6 +2786,7 @@ pub unsafe fn vtable_align(_ptr: *const ()) -> usize {
27862786
/// change the possible layouts of pointers.
27872787
#[rustc_nounwind]
27882788
#[unstable(feature = "core_intrinsics", issue = "none")]
2789+
#[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
27892790
#[rustc_intrinsic]
27902791
#[rustc_intrinsic_must_be_overridden]
27912792
#[cfg(not(bootstrap))]

‎library/core/src/ptr/metadata.rs

+24-8
Original file line numberDiff line numberDiff line change
@@ -2,6 +2,8 @@
22

33
use crate::fmt;
44
use crate::hash::{Hash, Hasher};
5+
#[cfg(not(bootstrap))]
6+
use crate::intrinsics::aggregate_raw_ptr;
57
use crate::marker::Freeze;
68

79
/// Provides the pointer metadata type of any pointed-to type.
@@ -113,10 +115,17 @@ pub const fn from_raw_parts<T: ?Sized>(
113115
data_pointer: *const (),
114116
metadata: <T as Pointee>::Metadata,
115117
) -> *const T {
116-
// SAFETY: Accessing the value from the `PtrRepr` union is safe since *const T
117-
// and PtrComponents<T> have the same memory layouts. Only std can make this
118-
// guarantee.
119-
unsafe { PtrRepr { components: PtrComponents { data_pointer, metadata } }.const_ptr }
118+
#[cfg(bootstrap)]
119+
{
120+
// SAFETY: Accessing the value from the `PtrRepr` union is safe since *const T
121+
// and PtrComponents<T> have the same memory layouts. Only std can make this
122+
// guarantee.
123+
unsafe { PtrRepr { components: PtrComponents { data_pointer, metadata } }.const_ptr }
124+
}
125+
#[cfg(not(bootstrap))]
126+
{
127+
aggregate_raw_ptr(data_pointer, metadata)
128+
}
120129
}
121130

122131
/// Performs the same functionality as [`from_raw_parts`], except that a
@@ -130,10 +139,17 @@ pub const fn from_raw_parts_mut<T: ?Sized>(
130139
data_pointer: *mut (),
131140
metadata: <T as Pointee>::Metadata,
132141
) -> *mut T {
133-
// SAFETY: Accessing the value from the `PtrRepr` union is safe since *const T
134-
// and PtrComponents<T> have the same memory layouts. Only std can make this
135-
// guarantee.
136-
unsafe { PtrRepr { components: PtrComponents { data_pointer, metadata } }.mut_ptr }
142+
#[cfg(bootstrap)]
143+
{
144+
// SAFETY: Accessing the value from the `PtrRepr` union is safe since *const T
145+
// and PtrComponents<T> have the same memory layouts. Only std can make this
146+
// guarantee.
147+
unsafe { PtrRepr { components: PtrComponents { data_pointer, metadata } }.mut_ptr }
148+
}
149+
#[cfg(not(bootstrap))]
150+
{
151+
aggregate_raw_ptr(data_pointer, metadata)
152+
}
137153
}
138154

139155
#[repr(C)]

‎library/core/tests/ptr.rs

+8
Original file line numberDiff line numberDiff line change
@@ -1163,3 +1163,11 @@ fn test_null_array_as_slice() {
11631163
assert!(ptr.is_null());
11641164
assert_eq!(ptr.len(), 4);
11651165
}
1166+
1167+
#[test]
1168+
fn test_ptr_from_raw_parts_in_const() {
1169+
const EMPTY_SLICE_PTR: *const [i32] =
1170+
std::ptr::slice_from_raw_parts(std::ptr::without_provenance(123), 456);
1171+
assert_eq!(EMPTY_SLICE_PTR.addr(), 123);
1172+
assert_eq!(EMPTY_SLICE_PTR.len(), 456);
1173+
}

‎library/core/tests/slice.rs

+13
Original file line numberDiff line numberDiff line change
@@ -2678,3 +2678,16 @@ fn test_get_many_mut_duplicate() {
26782678
let mut v = vec![1, 2, 3, 4, 5];
26792679
assert!(v.get_many_mut([1, 3, 3, 4]).is_err());
26802680
}
2681+
2682+
#[test]
2683+
fn test_slice_from_raw_parts_in_const() {
2684+
static FANCY: i32 = 4;
2685+
static FANCY_SLICE: &[i32] = unsafe { std::slice::from_raw_parts(&FANCY, 1) };
2686+
assert_eq!(FANCY_SLICE.as_ptr(), std::ptr::addr_of!(FANCY));
2687+
assert_eq!(FANCY_SLICE.len(), 1);
2688+
2689+
const EMPTY_SLICE: &[i32] =
2690+
unsafe { std::slice::from_raw_parts(std::ptr::without_provenance(123456), 0) };
2691+
assert_eq!(EMPTY_SLICE.as_ptr().addr(), 123456);
2692+
assert_eq!(EMPTY_SLICE.len(), 0);
2693+
}

‎tests/mir-opt/pre-codegen/slice_index.slice_ptr_get_unchecked_range.PreCodegen.after.panic-abort.mir

+55-5
Original file line numberDiff line numberDiff line change
@@ -4,16 +4,66 @@ fn slice_ptr_get_unchecked_range(_1: *const [u32], _2: std::ops::Range<usize>) -
44
debug slice => _1;
55
debug index => _2;
66
let mut _0: *const [u32];
7+
let mut _3: usize;
8+
let mut _4: usize;
79
scope 1 (inlined std::ptr::const_ptr::<impl *const [u32]>::get_unchecked::<std::ops::Range<usize>>) {
810
debug self => _1;
9-
debug index => _2;
11+
debug ((index: std::ops::Range<usize>).0: usize) => _3;
12+
debug ((index: std::ops::Range<usize>).1: usize) => _4;
13+
scope 2 (inlined <std::ops::Range<usize> as SliceIndex<[u32]>>::get_unchecked) {
14+
debug ((self: std::ops::Range<usize>).0: usize) => _3;
15+
debug ((self: std::ops::Range<usize>).1: usize) => _4;
16+
debug slice => _1;
17+
let _5: usize;
18+
let mut _6: *const u32;
19+
let mut _7: *const u32;
20+
scope 3 {
21+
debug new_len => _5;
22+
scope 6 (inlined std::ptr::const_ptr::<impl *const [u32]>::as_ptr) {
23+
debug self => _1;
24+
}
25+
scope 7 (inlined std::ptr::const_ptr::<impl *const u32>::add) {
26+
debug self => _6;
27+
debug count => _3;
28+
}
29+
scope 8 (inlined slice_from_raw_parts::<u32>) {
30+
debug data => _7;
31+
debug len => _5;
32+
let mut _8: *const ();
33+
scope 9 (inlined std::ptr::const_ptr::<impl *const u32>::cast::<()>) {
34+
debug self => _7;
35+
}
36+
scope 10 (inlined std::ptr::from_raw_parts::<[u32]>) {
37+
debug data_pointer => _8;
38+
debug metadata => _5;
39+
}
40+
}
41+
}
42+
scope 4 (inlined std::ptr::const_ptr::<impl *const [u32]>::len) {
43+
debug self => _1;
44+
scope 5 (inlined std::ptr::metadata::<[u32]>) {
45+
debug ptr => _1;
46+
}
47+
}
48+
}
1049
}
1150

1251
bb0: {
13-
_0 = <std::ops::Range<usize> as SliceIndex<[u32]>>::get_unchecked(move _2, move _1) -> [return: bb1, unwind unreachable];
14-
}
15-
16-
bb1: {
52+
_3 = move (_2.0: usize);
53+
_4 = move (_2.1: usize);
54+
StorageLive(_5);
55+
_5 = SubUnchecked(_4, _3);
56+
StorageLive(_7);
57+
StorageLive(_6);
58+
_6 = _1 as *const u32 (PtrToPtr);
59+
_7 = Offset(_6, _3);
60+
StorageDead(_6);
61+
StorageLive(_8);
62+
_8 = _7 as *const () (PtrToPtr);
63+
_0 = *const [u32] from (_8, _5);
64+
StorageDead(_8);
65+
StorageDead(_7);
66+
StorageDead(_5);
1767
return;
1868
}
1969
}

‎tests/mir-opt/pre-codegen/slice_index.slice_ptr_get_unchecked_range.PreCodegen.after.panic-unwind.mir

+55-5
Original file line numberDiff line numberDiff line change
@@ -4,16 +4,66 @@ fn slice_ptr_get_unchecked_range(_1: *const [u32], _2: std::ops::Range<usize>) -
44
debug slice => _1;
55
debug index => _2;
66
let mut _0: *const [u32];
7+
let mut _3: usize;
8+
let mut _4: usize;
79
scope 1 (inlined std::ptr::const_ptr::<impl *const [u32]>::get_unchecked::<std::ops::Range<usize>>) {
810
debug self => _1;
9-
debug index => _2;
11+
debug ((index: std::ops::Range<usize>).0: usize) => _3;
12+
debug ((index: std::ops::Range<usize>).1: usize) => _4;
13+
scope 2 (inlined <std::ops::Range<usize> as SliceIndex<[u32]>>::get_unchecked) {
14+
debug ((self: std::ops::Range<usize>).0: usize) => _3;
15+
debug ((self: std::ops::Range<usize>).1: usize) => _4;
16+
debug slice => _1;
17+
let _5: usize;
18+
let mut _6: *const u32;
19+
let mut _7: *const u32;
20+
scope 3 {
21+
debug new_len => _5;
22+
scope 6 (inlined std::ptr::const_ptr::<impl *const [u32]>::as_ptr) {
23+
debug self => _1;
24+
}
25+
scope 7 (inlined std::ptr::const_ptr::<impl *const u32>::add) {
26+
debug self => _6;
27+
debug count => _3;
28+
}
29+
scope 8 (inlined slice_from_raw_parts::<u32>) {
30+
debug data => _7;
31+
debug len => _5;
32+
let mut _8: *const ();
33+
scope 9 (inlined std::ptr::const_ptr::<impl *const u32>::cast::<()>) {
34+
debug self => _7;
35+
}
36+
scope 10 (inlined std::ptr::from_raw_parts::<[u32]>) {
37+
debug data_pointer => _8;
38+
debug metadata => _5;
39+
}
40+
}
41+
}
42+
scope 4 (inlined std::ptr::const_ptr::<impl *const [u32]>::len) {
43+
debug self => _1;
44+
scope 5 (inlined std::ptr::metadata::<[u32]>) {
45+
debug ptr => _1;
46+
}
47+
}
48+
}
1049
}
1150

1251
bb0: {
13-
_0 = <std::ops::Range<usize> as SliceIndex<[u32]>>::get_unchecked(move _2, move _1) -> [return: bb1, unwind continue];
14-
}
15-
16-
bb1: {
52+
_3 = move (_2.0: usize);
53+
_4 = move (_2.1: usize);
54+
StorageLive(_5);
55+
_5 = SubUnchecked(_4, _3);
56+
StorageLive(_7);
57+
StorageLive(_6);
58+
_6 = _1 as *const u32 (PtrToPtr);
59+
_7 = Offset(_6, _3);
60+
StorageDead(_6);
61+
StorageLive(_8);
62+
_8 = _7 as *const () (PtrToPtr);
63+
_0 = *const [u32] from (_8, _5);
64+
StorageDead(_8);
65+
StorageDead(_7);
66+
StorageDead(_5);
1767
return;
1868
}
1969
}

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