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Avoid a cast in ptr::slice_from_raw_parts(_mut)

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Casting to `*const ()` or `*mut ()` just bloats the MIR, so let's not.

If ACP#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.
This commit is contained in:
Scott McMurray 2024-05-06 01:44:27 -07:00
parent d287f3e4ee
commit 61517dbbe6
8 changed files with 130 additions and 78 deletions
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4
library/core/src/ptr/mod.rs
View File

@ -812,7 +812,7 @@ pub const fn from_mut<T: ?Sized>(r: &mut T) -> *mut T {
#[rustc_allow_const_fn_unstable(ptr_metadata)]
#[rustc_diagnostic_item = "ptr_slice_from_raw_parts"]
pub const fn slice_from_raw_parts<T>(data: *const T, len: usize) -> *const [T] {
from_raw_parts(data.cast(), len)
intrinsics::aggregate_raw_ptr(data, len)
}
/// 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] {
#[rustc_const_unstable(feature = "const_slice_from_raw_parts_mut", issue = "67456")]
#[rustc_diagnostic_item = "ptr_slice_from_raw_parts_mut"]
pub const fn slice_from_raw_parts_mut<T>(data: *mut T, len: usize) -> *mut [T] {
from_raw_parts_mut(data.cast(), len)
intrinsics::aggregate_raw_ptr(data, len)
}
/// Swaps the values at two mutable locations of the same type, without

56
tests/mir-opt/inline/inline_shims.drop.Inline.panic-abort.diff
View File

@ -11,10 +11,28 @@
+ scope 1 (inlined std::ptr::drop_in_place::<Vec<A>> - shim(Some(Vec<A>))) {
+ let mut _6: &mut std::vec::Vec<A>;
+ let mut _7: ();
+ scope 2 (inlined <Vec<A> as Drop>::drop) {
+ let mut _8: *mut [A];
+ let mut _9: *mut A;
+ let mut _10: usize;
+ scope 3 (inlined Vec::<A>::as_mut_ptr) {
+ let mut _11: &alloc::raw_vec::RawVec<A>;
+ scope 4 (inlined alloc::raw_vec::RawVec::<A>::ptr) {
+ let mut _13: std::ptr::NonNull<A>;
+ scope 5 (inlined Unique::<A>::as_ptr) {
+ scope 6 (inlined NonNull::<A>::as_ptr) {
+ let mut _12: *const A;
+ }
+ scope 2 (inlined std::ptr::drop_in_place::<Option<B>> - shim(Some(Option<B>))) {
+ let mut _8: isize;
+ let mut _9: isize;
+ }
+ }
+ }
+ scope 7 (inlined slice_from_raw_parts_mut::<A>) {
+ }
+ }
+ }
+ scope 8 (inlined std::ptr::drop_in_place::<Option<B>> - shim(Some(Option<B>))) {
+ let mut _14: isize;
+ let mut _15: isize;
+ }
bb0: {
@ -25,7 +43,24 @@
+ StorageLive(_6);
+ StorageLive(_7);
+ _6 = &mut (*_4);
+ _7 = <Vec<A> as Drop>::drop(move _6) -> [return: bb2, unwind unreachable];
+ StorageLive(_8);
+ StorageLive(_9);
+ StorageLive(_11);
+ _11 = &((*_6).0: alloc::raw_vec::RawVec<A>);
+ StorageLive(_13);
+ _13 = ((((*_6).0: alloc::raw_vec::RawVec<A>).0: std::ptr::Unique<A>).0: std::ptr::NonNull<A>);
+ StorageLive(_12);
+ _12 = (_13.0: *const A);
+ _9 = move _12 as *mut A (PtrToPtr);
+ StorageDead(_12);
+ StorageDead(_13);
+ StorageDead(_11);
+ StorageLive(_10);
+ _10 = ((*_6).1: usize);
+ _8 = *mut [A] from (_9, _10);
+ StorageDead(_10);
+ StorageDead(_9);
+ _7 = std::ptr::drop_in_place::<[A]>(move _8) -> [return: bb2, unwind unreachable];
}
bb1: {
@ -36,19 +71,20 @@
StorageLive(_5);
_5 = _2;
- _0 = std::ptr::drop_in_place::<Option<B>>(move _5) -> [return: bb2, unwind unreachable];
+ StorageLive(_8);
+ StorageLive(_9);
+ _8 = discriminant((*_5));
+ switchInt(move _8) -> [0: bb3, otherwise: bb4];
+ StorageLive(_14);
+ StorageLive(_15);
+ _14 = discriminant((*_5));
+ switchInt(move _14) -> [0: bb3, otherwise: bb4];
}
bb2: {
+ StorageDead(_8);
+ drop(((*_4).0: alloc::raw_vec::RawVec<A>)) -> [return: bb1, unwind unreachable];
+ }
+
+ bb3: {
+ StorageDead(_9);
+ StorageDead(_8);
+ StorageDead(_15);
+ StorageDead(_14);
StorageDead(_5);
return;
+ }

47
tests/mir-opt/pre-codegen/slice_index.slice_get_unchecked_mut_range.PreCodegen.after.panic-abort.mir
View File

@ -4,20 +4,47 @@ fn slice_get_unchecked_mut_range(_1: &mut [u32], _2: std::ops::Range<usize>) ->
debug slice => _1;
debug index => _2;
let mut _0: &mut [u32];
let mut _3: usize;
let mut _4: usize;
scope 1 (inlined core::slice::<impl [u32]>::get_unchecked_mut::<std::ops::Range<usize>>) {
let mut _3: *mut [u32];
let mut _4: *mut [u32];
let mut _5: *mut [u32];
let mut _9: *mut [u32];
scope 2 (inlined <std::ops::Range<usize> as SliceIndex<[u32]>>::get_unchecked_mut) {
let _6: usize;
let mut _7: *mut u32;
let mut _8: *mut u32;
scope 3 {
scope 6 (inlined std::ptr::mut_ptr::<impl *mut [u32]>::as_mut_ptr) {
}
scope 7 (inlined std::ptr::mut_ptr::<impl *mut u32>::add) {
}
scope 8 (inlined slice_from_raw_parts_mut::<u32>) {
}
}
scope 4 (inlined std::ptr::mut_ptr::<impl *mut [u32]>::len) {
scope 5 (inlined std::ptr::metadata::<[u32]>) {
}
}
}
}
bb0: {
StorageLive(_3);
_3 = &raw mut (*_1);
_4 = <std::ops::Range<usize> as SliceIndex<[u32]>>::get_unchecked_mut(move _2, move _3) -> [return: bb1, unwind unreachable];
}
bb1: {
StorageDead(_3);
_0 = &mut (*_4);
_3 = move (_2.0: usize);
_4 = move (_2.1: usize);
StorageLive(_5);
_5 = &raw mut (*_1);
StorageLive(_6);
_6 = SubUnchecked(_4, _3);
StorageLive(_8);
StorageLive(_7);
_7 = _5 as *mut u32 (PtrToPtr);
_8 = Offset(_7, _3);
StorageDead(_7);
_9 = *mut [u32] from (_8, _6);
StorageDead(_8);
StorageDead(_6);
StorageDead(_5);
_0 = &mut (*_9);
return;
}
}

47
tests/mir-opt/pre-codegen/slice_index.slice_get_unchecked_mut_range.PreCodegen.after.panic-unwind.mir
View File

@ -4,20 +4,47 @@ fn slice_get_unchecked_mut_range(_1: &mut [u32], _2: std::ops::Range<usize>) ->
debug slice => _1;
debug index => _2;
let mut _0: &mut [u32];
let mut _3: usize;
let mut _4: usize;
scope 1 (inlined core::slice::<impl [u32]>::get_unchecked_mut::<std::ops::Range<usize>>) {
let mut _3: *mut [u32];
let mut _4: *mut [u32];
let mut _5: *mut [u32];
let mut _9: *mut [u32];
scope 2 (inlined <std::ops::Range<usize> as SliceIndex<[u32]>>::get_unchecked_mut) {
let _6: usize;
let mut _7: *mut u32;
let mut _8: *mut u32;
scope 3 {
scope 6 (inlined std::ptr::mut_ptr::<impl *mut [u32]>::as_mut_ptr) {
}
scope 7 (inlined std::ptr::mut_ptr::<impl *mut u32>::add) {
}
scope 8 (inlined slice_from_raw_parts_mut::<u32>) {
}
}
scope 4 (inlined std::ptr::mut_ptr::<impl *mut [u32]>::len) {
scope 5 (inlined std::ptr::metadata::<[u32]>) {
}
}
}
}
bb0: {
StorageLive(_3);
_3 = &raw mut (*_1);
_4 = <std::ops::Range<usize> as SliceIndex<[u32]>>::get_unchecked_mut(move _2, move _3) -> [return: bb1, unwind continue];
}
bb1: {
StorageDead(_3);
_0 = &mut (*_4);
_3 = move (_2.0: usize);
_4 = move (_2.1: usize);
StorageLive(_5);
_5 = &raw mut (*_1);
StorageLive(_6);
_6 = SubUnchecked(_4, _3);
StorageLive(_8);
StorageLive(_7);
_7 = _5 as *mut u32 (PtrToPtr);
_8 = Offset(_7, _3);
StorageDead(_7);
_9 = *mut [u32] from (_8, _6);
StorageDead(_8);
StorageDead(_6);
StorageDead(_5);
_0 = &mut (*_9);
return;
}
}

10
tests/mir-opt/pre-codegen/slice_index.slice_ptr_get_unchecked_range.PreCodegen.after.panic-abort.mir
View File

@ -17,11 +17,6 @@ fn slice_ptr_get_unchecked_range(_1: *const [u32], _2: std::ops::Range<usize>) -
scope 7 (inlined std::ptr::const_ptr::<impl *const u32>::add) {
}
scope 8 (inlined slice_from_raw_parts::<u32>) {
let mut _8: *const ();
scope 9 (inlined std::ptr::const_ptr::<impl *const u32>::cast::<()>) {
}
scope 10 (inlined std::ptr::from_raw_parts::<[u32]>) {
}
}
}
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>) -
_6 = _1 as *const u32 (PtrToPtr);
_7 = Offset(_6, _3);
StorageDead(_6);
StorageLive(_8);
_8 = _7 as *const () (PtrToPtr);
_0 = *const [u32] from (_8, _5);
StorageDead(_8);
_0 = *const [u32] from (_7, _5);
StorageDead(_7);
StorageDead(_5);
return;

10
tests/mir-opt/pre-codegen/slice_index.slice_ptr_get_unchecked_range.PreCodegen.after.panic-unwind.mir
View File

@ -17,11 +17,6 @@ fn slice_ptr_get_unchecked_range(_1: *const [u32], _2: std::ops::Range<usize>) -
scope 7 (inlined std::ptr::const_ptr::<impl *const u32>::add) {
}
scope 8 (inlined slice_from_raw_parts::<u32>) {
let mut _8: *const ();
scope 9 (inlined std::ptr::const_ptr::<impl *const u32>::cast::<()>) {
}
scope 10 (inlined std::ptr::from_raw_parts::<[u32]>) {
}
}
}
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>) -
_6 = _1 as *const u32 (PtrToPtr);
_7 = Offset(_6, _3);
StorageDead(_6);
StorageLive(_8);
_8 = _7 as *const () (PtrToPtr);
_0 = *const [u32] from (_8, _5);
StorageDead(_8);
_0 = *const [u32] from (_7, _5);
StorageDead(_7);
StorageDead(_5);
return;

17
tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-abort.mir
View File

@ -25,7 +25,7 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
scope 6 (inlined std::slice::from_raw_parts::<'_, u8>) {
debug data => _4;
debug len => _5;
let _7: *const [u8];
let _6: *const [u8];
scope 7 (inlined core::ub_checks::check_language_ub) {
scope 8 (inlined core::ub_checks::check_language_ub::runtime) {
}
@ -37,14 +37,6 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
scope 11 (inlined slice_from_raw_parts::<u8>) {
debug data => _4;
debug len => _5;
let mut _6: *const ();
scope 12 (inlined std::ptr::const_ptr::<impl *const u8>::cast::<()>) {
debug self => _4;
}
scope 13 (inlined std::ptr::from_raw_parts::<[u8]>) {
debug data_pointer => _6;
debug metadata => _5;
}
}
}
}
@ -60,13 +52,10 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
StorageDead(_2);
StorageLive(_5);
_5 = ((*_1).1: usize);
StorageLive(_6);
_6 = _4 as *const () (PtrToPtr);
_7 = *const [u8] from (_6, _5);
StorageDead(_6);
_6 = *const [u8] from (_4, _5);
StorageDead(_5);
StorageDead(_4);
_0 = &(*_7);
_0 = &(*_6);
return;
}
}

17
tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-unwind.mir
View File

@ -25,7 +25,7 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
scope 6 (inlined std::slice::from_raw_parts::<'_, u8>) {
debug data => _4;
debug len => _5;
let _7: *const [u8];
let _6: *const [u8];
scope 7 (inlined core::ub_checks::check_language_ub) {
scope 8 (inlined core::ub_checks::check_language_ub::runtime) {
}
@ -37,14 +37,6 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
scope 11 (inlined slice_from_raw_parts::<u8>) {
debug data => _4;
debug len => _5;
let mut _6: *const ();
scope 12 (inlined std::ptr::const_ptr::<impl *const u8>::cast::<()>) {
debug self => _4;
}
scope 13 (inlined std::ptr::from_raw_parts::<[u8]>) {
debug data_pointer => _6;
debug metadata => _5;
}
}
}
}
@ -60,13 +52,10 @@ fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
StorageDead(_2);
StorageLive(_5);
_5 = ((*_1).1: usize);
StorageLive(_6);
_6 = _4 as *const () (PtrToPtr);
_7 = *const [u8] from (_6, _5);
StorageDead(_6);
_6 = *const [u8] from (_4, _5);
StorageDead(_5);
StorageDead(_4);
_0 = &(*_7);
_0 = &(*_6);
return;
}
}