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Auto merge of #124795 - scottmcm:simplify-slice-from-raw-parts, r=<try>
Avoid a cast in `ptr::slice_from_raw_parts(_mut)` Casting to `*const ()` or `*mut ()` is no longer needed after #123840 so let's make the MIR smaller (and more inline-able, as seen in the tests). If [ACP#362](rust-lang/libs-team#362) goes through we can keep calling `ptr::from_raw_parts(_mut)` in these also without the cast, but that hasn't had any libs-api attention yet, so I'm not waiting on it.
2 parents e2865db + 61517db commit 8466125

8 files changed

+130
-78
lines changed

‎library/core/src/ptr/mod.rs

+2-2
Original file line numberDiff line numberDiff line change
@@ -812,7 +812,7 @@ pub const fn from_mut<T: ?Sized>(r: &mut T) -> *mut T {
812812
#[rustc_allow_const_fn_unstable(ptr_metadata)]
813813
#[rustc_diagnostic_item = "ptr_slice_from_raw_parts"]
814814
pub const fn slice_from_raw_parts<T>(data: *const T, len: usize) -> *const [T] {
815-
from_raw_parts(data.cast(), len)
815+
intrinsics::aggregate_raw_ptr(data, len)
816816
}
817817

818818
/// Forms a raw mutable slice from a pointer and a length.
@@ -858,7 +858,7 @@ pub const fn slice_from_raw_parts<T>(data: *const T, len: usize) -> *const [T] {
858858
#[rustc_const_unstable(feature = "const_slice_from_raw_parts_mut", issue = "67456")]
859859
#[rustc_diagnostic_item = "ptr_slice_from_raw_parts_mut"]
860860
pub const fn slice_from_raw_parts_mut<T>(data: *mut T, len: usize) -> *mut [T] {
861-
from_raw_parts_mut(data.cast(), len)
861+
intrinsics::aggregate_raw_ptr(data, len)
862862
}
863863

864864
/// Swaps the values at two mutable locations of the same type, without

‎tests/mir-opt/inline/inline_shims.drop.Inline.panic-abort.diff

+46-10
Original file line numberDiff line numberDiff line change
@@ -11,10 +11,28 @@
1111
+ scope 1 (inlined std::ptr::drop_in_place::<Vec<A>> - shim(Some(Vec<A>))) {
1212
+ let mut _6: &mut std::vec::Vec<A>;
1313
+ let mut _7: ();
14+
+ scope 2 (inlined <Vec<A> as Drop>::drop) {
15+
+ let mut _8: *mut [A];
16+
+ let mut _9: *mut A;
17+
+ let mut _10: usize;
18+
+ scope 3 (inlined Vec::<A>::as_mut_ptr) {
19+
+ let mut _11: &alloc::raw_vec::RawVec<A>;
20+
+ scope 4 (inlined alloc::raw_vec::RawVec::<A>::ptr) {
21+
+ let mut _13: std::ptr::NonNull<A>;
22+
+ scope 5 (inlined Unique::<A>::as_ptr) {
23+
+ scope 6 (inlined NonNull::<A>::as_ptr) {
24+
+ let mut _12: *const A;
25+
+ }
26+
+ }
27+
+ }
28+
+ }
29+
+ scope 7 (inlined slice_from_raw_parts_mut::<A>) {
30+
+ }
31+
+ }
1432
+ }
15-
+ scope 2 (inlined std::ptr::drop_in_place::<Option<B>> - shim(Some(Option<B>))) {
16-
+ let mut _8: isize;
17-
+ let mut _9: isize;
33+
+ scope 8 (inlined std::ptr::drop_in_place::<Option<B>> - shim(Some(Option<B>))) {
34+
+ let mut _14: isize;
35+
+ let mut _15: isize;
1836
+ }
1937

2038
bb0: {
@@ -25,7 +43,24 @@
2543
+ StorageLive(_6);
2644
+ StorageLive(_7);
2745
+ _6 = &mut (*_4);
28-
+ _7 = <Vec<A> as Drop>::drop(move _6) -> [return: bb2, unwind unreachable];
46+
+ StorageLive(_8);
47+
+ StorageLive(_9);
48+
+ StorageLive(_11);
49+
+ _11 = &((*_6).0: alloc::raw_vec::RawVec<A>);
50+
+ StorageLive(_13);
51+
+ _13 = ((((*_6).0: alloc::raw_vec::RawVec<A>).0: std::ptr::Unique<A>).0: std::ptr::NonNull<A>);
52+
+ StorageLive(_12);
53+
+ _12 = (_13.0: *const A);
54+
+ _9 = move _12 as *mut A (PtrToPtr);
55+
+ StorageDead(_12);
56+
+ StorageDead(_13);
57+
+ StorageDead(_11);
58+
+ StorageLive(_10);
59+
+ _10 = ((*_6).1: usize);
60+
+ _8 = *mut [A] from (_9, _10);
61+
+ StorageDead(_10);
62+
+ StorageDead(_9);
63+
+ _7 = std::ptr::drop_in_place::<[A]>(move _8) -> [return: bb2, unwind unreachable];
2964
}
3065

3166
bb1: {
@@ -36,19 +71,20 @@
3671
StorageLive(_5);
3772
_5 = _2;
3873
- _0 = std::ptr::drop_in_place::<Option<B>>(move _5) -> [return: bb2, unwind unreachable];
39-
+ StorageLive(_8);
40-
+ StorageLive(_9);
41-
+ _8 = discriminant((*_5));
42-
+ switchInt(move _8) -> [0: bb3, otherwise: bb4];
74+
+ StorageLive(_14);
75+
+ StorageLive(_15);
76+
+ _14 = discriminant((*_5));
77+
+ switchInt(move _14) -> [0: bb3, otherwise: bb4];
4378
}
4479

4580
bb2: {
81+
+ StorageDead(_8);
4682
+ drop(((*_4).0: alloc::raw_vec::RawVec<A>)) -> [return: bb1, unwind unreachable];
4783
+ }
4884
+
4985
+ bb3: {
50-
+ StorageDead(_9);
51-
+ StorageDead(_8);
86+
+ StorageDead(_15);
87+
+ StorageDead(_14);
5288
StorageDead(_5);
5389
return;
5490
+ }

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

+37-10
Original file line numberDiff line numberDiff line change
@@ -4,20 +4,47 @@ fn slice_get_unchecked_mut_range(_1: &mut [u32], _2: std::ops::Range<usize>) ->
44
debug slice => _1;
55
debug index => _2;
66
let mut _0: &mut [u32];
7+
let mut _3: usize;
8+
let mut _4: usize;
79
scope 1 (inlined core::slice::<impl [u32]>::get_unchecked_mut::<std::ops::Range<usize>>) {
8-
let mut _3: *mut [u32];
9-
let mut _4: *mut [u32];
10+
let mut _5: *mut [u32];
11+
let mut _9: *mut [u32];
12+
scope 2 (inlined <std::ops::Range<usize> as SliceIndex<[u32]>>::get_unchecked_mut) {
13+
let _6: usize;
14+
let mut _7: *mut u32;
15+
let mut _8: *mut u32;
16+
scope 3 {
17+
scope 6 (inlined std::ptr::mut_ptr::<impl *mut [u32]>::as_mut_ptr) {
18+
}
19+
scope 7 (inlined std::ptr::mut_ptr::<impl *mut u32>::add) {
20+
}
21+
scope 8 (inlined slice_from_raw_parts_mut::<u32>) {
22+
}
23+
}
24+
scope 4 (inlined std::ptr::mut_ptr::<impl *mut [u32]>::len) {
25+
scope 5 (inlined std::ptr::metadata::<[u32]>) {
26+
}
27+
}
28+
}
1029
}
1130

1231
bb0: {
13-
StorageLive(_3);
14-
_3 = &raw mut (*_1);
15-
_4 = <std::ops::Range<usize> as SliceIndex<[u32]>>::get_unchecked_mut(move _2, move _3) -> [return: bb1, unwind unreachable];
16-
}
17-
18-
bb1: {
19-
StorageDead(_3);
20-
_0 = &mut (*_4);
32+
_3 = move (_2.0: usize);
33+
_4 = move (_2.1: usize);
34+
StorageLive(_5);
35+
_5 = &raw mut (*_1);
36+
StorageLive(_6);
37+
_6 = SubUnchecked(_4, _3);
38+
StorageLive(_8);
39+
StorageLive(_7);
40+
_7 = _5 as *mut u32 (PtrToPtr);
41+
_8 = Offset(_7, _3);
42+
StorageDead(_7);
43+
_9 = *mut [u32] from (_8, _6);
44+
StorageDead(_8);
45+
StorageDead(_6);
46+
StorageDead(_5);
47+
_0 = &mut (*_9);
2148
return;
2249
}
2350
}

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

+37-10
Original file line numberDiff line numberDiff line change
@@ -4,20 +4,47 @@ fn slice_get_unchecked_mut_range(_1: &mut [u32], _2: std::ops::Range<usize>) ->
44
debug slice => _1;
55
debug index => _2;
66
let mut _0: &mut [u32];
7+
let mut _3: usize;
8+
let mut _4: usize;
79
scope 1 (inlined core::slice::<impl [u32]>::get_unchecked_mut::<std::ops::Range<usize>>) {
8-
let mut _3: *mut [u32];
9-
let mut _4: *mut [u32];
10+
let mut _5: *mut [u32];
11+
let mut _9: *mut [u32];
12+
scope 2 (inlined <std::ops::Range<usize> as SliceIndex<[u32]>>::get_unchecked_mut) {
13+
let _6: usize;
14+
let mut _7: *mut u32;
15+
let mut _8: *mut u32;
16+
scope 3 {
17+
scope 6 (inlined std::ptr::mut_ptr::<impl *mut [u32]>::as_mut_ptr) {
18+
}
19+
scope 7 (inlined std::ptr::mut_ptr::<impl *mut u32>::add) {
20+
}
21+
scope 8 (inlined slice_from_raw_parts_mut::<u32>) {
22+
}
23+
}
24+
scope 4 (inlined std::ptr::mut_ptr::<impl *mut [u32]>::len) {
25+
scope 5 (inlined std::ptr::metadata::<[u32]>) {
26+
}
27+
}
28+
}
1029
}
1130

1231
bb0: {
13-
StorageLive(_3);
14-
_3 = &raw mut (*_1);
15-
_4 = <std::ops::Range<usize> as SliceIndex<[u32]>>::get_unchecked_mut(move _2, move _3) -> [return: bb1, unwind continue];
16-
}
17-
18-
bb1: {
19-
StorageDead(_3);
20-
_0 = &mut (*_4);
32+
_3 = move (_2.0: usize);
33+
_4 = move (_2.1: usize);
34+
StorageLive(_5);
35+
_5 = &raw mut (*_1);
36+
StorageLive(_6);
37+
_6 = SubUnchecked(_4, _3);
38+
StorageLive(_8);
39+
StorageLive(_7);
40+
_7 = _5 as *mut u32 (PtrToPtr);
41+
_8 = Offset(_7, _3);
42+
StorageDead(_7);
43+
_9 = *mut [u32] from (_8, _6);
44+
StorageDead(_8);
45+
StorageDead(_6);
46+
StorageDead(_5);
47+
_0 = &mut (*_9);
2148
return;
2249
}
2350
}

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

+1-9
Original file line numberDiff line numberDiff line change
@@ -17,11 +17,6 @@ fn slice_ptr_get_unchecked_range(_1: *const [u32], _2: std::ops::Range<usize>) -
1717
scope 7 (inlined std::ptr::const_ptr::<impl *const u32>::add) {
1818
}
1919
scope 8 (inlined slice_from_raw_parts::<u32>) {
20-
let mut _8: *const ();
21-
scope 9 (inlined std::ptr::const_ptr::<impl *const u32>::cast::<()>) {
22-
}
23-
scope 10 (inlined std::ptr::from_raw_parts::<[u32]>) {
24-
}
2520
}
2621
}
2722
scope 4 (inlined std::ptr::const_ptr::<impl *const [u32]>::len) {
@@ -41,10 +36,7 @@ fn slice_ptr_get_unchecked_range(_1: *const [u32], _2: std::ops::Range<usize>) -
4136
_6 = _1 as *const u32 (PtrToPtr);
4237
_7 = Offset(_6, _3);
4338
StorageDead(_6);
44-
StorageLive(_8);
45-
_8 = _7 as *const () (PtrToPtr);
46-
_0 = *const [u32] from (_8, _5);
47-
StorageDead(_8);
39+
_0 = *const [u32] from (_7, _5);
4840
StorageDead(_7);
4941
StorageDead(_5);
5042
return;

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

+1-9
Original file line numberDiff line numberDiff line change
@@ -17,11 +17,6 @@ fn slice_ptr_get_unchecked_range(_1: *const [u32], _2: std::ops::Range<usize>) -
1717
scope 7 (inlined std::ptr::const_ptr::<impl *const u32>::add) {
1818
}
1919
scope 8 (inlined slice_from_raw_parts::<u32>) {
20-
let mut _8: *const ();
21-
scope 9 (inlined std::ptr::const_ptr::<impl *const u32>::cast::<()>) {
22-
}
23-
scope 10 (inlined std::ptr::from_raw_parts::<[u32]>) {
24-
}
2520
}
2621
}
2722
scope 4 (inlined std::ptr::const_ptr::<impl *const [u32]>::len) {
@@ -41,10 +36,7 @@ fn slice_ptr_get_unchecked_range(_1: *const [u32], _2: std::ops::Range<usize>) -
4136
_6 = _1 as *const u32 (PtrToPtr);
4237
_7 = Offset(_6, _3);
4338
StorageDead(_6);
44-
StorageLive(_8);
45-
_8 = _7 as *const () (PtrToPtr);
46-
_0 = *const [u32] from (_8, _5);
47-
StorageDead(_8);
39+
_0 = *const [u32] from (_7, _5);
4840
StorageDead(_7);
4941
StorageDead(_5);
5042
return;

‎tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-abort.mir

+3-14
Original file line numberDiff line numberDiff line change
@@ -25,7 +25,7 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
2525
scope 6 (inlined std::slice::from_raw_parts::<'_, u8>) {
2626
debug data => _4;
2727
debug len => _5;
28-
let _7: *const [u8];
28+
let _6: *const [u8];
2929
scope 7 (inlined core::ub_checks::check_language_ub) {
3030
scope 8 (inlined core::ub_checks::check_language_ub::runtime) {
3131
}
@@ -37,14 +37,6 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
3737
scope 11 (inlined slice_from_raw_parts::<u8>) {
3838
debug data => _4;
3939
debug len => _5;
40-
let mut _6: *const ();
41-
scope 12 (inlined std::ptr::const_ptr::<impl *const u8>::cast::<()>) {
42-
debug self => _4;
43-
}
44-
scope 13 (inlined std::ptr::from_raw_parts::<[u8]>) {
45-
debug data_pointer => _6;
46-
debug metadata => _5;
47-
}
4840
}
4941
}
5042
}
@@ -60,13 +52,10 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
6052
StorageDead(_2);
6153
StorageLive(_5);
6254
_5 = ((*_1).1: usize);
63-
StorageLive(_6);
64-
_6 = _4 as *const () (PtrToPtr);
65-
_7 = *const [u8] from (_6, _5);
66-
StorageDead(_6);
55+
_6 = *const [u8] from (_4, _5);
6756
StorageDead(_5);
6857
StorageDead(_4);
69-
_0 = &(*_7);
58+
_0 = &(*_6);
7059
return;
7160
}
7261
}

‎tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-unwind.mir

+3-14
Original file line numberDiff line numberDiff line change
@@ -25,7 +25,7 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
2525
scope 6 (inlined std::slice::from_raw_parts::<'_, u8>) {
2626
debug data => _4;
2727
debug len => _5;
28-
let _7: *const [u8];
28+
let _6: *const [u8];
2929
scope 7 (inlined core::ub_checks::check_language_ub) {
3030
scope 8 (inlined core::ub_checks::check_language_ub::runtime) {
3131
}
@@ -37,14 +37,6 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
3737
scope 11 (inlined slice_from_raw_parts::<u8>) {
3838
debug data => _4;
3939
debug len => _5;
40-
let mut _6: *const ();
41-
scope 12 (inlined std::ptr::const_ptr::<impl *const u8>::cast::<()>) {
42-
debug self => _4;
43-
}
44-
scope 13 (inlined std::ptr::from_raw_parts::<[u8]>) {
45-
debug data_pointer => _6;
46-
debug metadata => _5;
47-
}
4840
}
4941
}
5042
}
@@ -60,13 +52,10 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
6052
StorageDead(_2);
6153
StorageLive(_5);
6254
_5 = ((*_1).1: usize);
63-
StorageLive(_6);
64-
_6 = _4 as *const () (PtrToPtr);
65-
_7 = *const [u8] from (_6, _5);
66-
StorageDead(_6);
55+
_6 = *const [u8] from (_4, _5);
6756
StorageDead(_5);
6857
StorageDead(_4);
69-
_0 = &(*_7);
58+
_0 = &(*_6);
7059
return;
7160
}
7261
}

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