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Also use mir::Offset for pointer add
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@scottmcm
scottmcm committed Apr 28, 2023
1 parent 8bcfc0e commit e1da77c
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Showing 11 changed files with 117 additions and 77 deletions.
11 changes: 9 additions & 2 deletions compiler/rustc_codegen_ssa/src/mir/rvalue.rs
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Expand Up @@ -819,8 +819,15 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
.builtin_deref(true)
.unwrap_or_else(|| bug!("deref of non-pointer {:?}", input_ty))
.ty;
let llty = bx.cx().backend_type(bx.cx().layout_of(pointee_type));
bx.inbounds_gep(llty, lhs, &[rhs])
let pointee_layout = bx.cx().layout_of(pointee_type);
if pointee_layout.is_zst() {
// `Offset` works in terms of the size of pointee,
// so offsetting a pointer to ZST is a noop.
lhs
} else {
let llty = bx.cx().backend_type(pointee_layout);
bx.inbounds_gep(llty, lhs, &[rhs])
}
}
mir::BinOp::Shl => common::build_unchecked_lshift(bx, lhs, rhs),
mir::BinOp::Shr => common::build_unchecked_rshift(bx, input_ty, lhs, rhs),
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3 changes: 2 additions & 1 deletion compiler/rustc_hir_analysis/src/check/intrinsic.rs
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Expand Up @@ -215,7 +215,8 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {

sym::type_name => (1, Vec::new(), tcx.mk_static_str()),
sym::type_id => (1, Vec::new(), tcx.types.u64),
sym::offset | sym::arith_offset => (
sym::offset => (2, vec![param(0), param(1)], param(0)),
sym::arith_offset => (
1,
vec![
tcx.mk_ptr(ty::TypeAndMut { ty: param(0), mutbl: hir::Mutability::Not }),
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12 changes: 12 additions & 0 deletions library/core/src/intrinsics.rs
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Expand Up @@ -1413,6 +1413,10 @@ extern "rust-intrinsic" {
/// This is implemented as an intrinsic to avoid converting to and from an
/// integer, since the conversion would throw away aliasing information.
///
/// This can only be used with `Ptr` as a raw pointer type (`*mut` or `*const`)
/// to a `Sized` pointee and with `Delta` as `usize` or `isize`. Any other
/// instantiations may arbitrarily misbehave, and that's *not* a compiler bug.
///
/// # Safety
///
/// Both the starting and resulting pointer must be either in bounds or one
Expand All @@ -1421,6 +1425,14 @@ extern "rust-intrinsic" {
/// returned value will result in undefined behavior.
///
/// The stabilized version of this intrinsic is [`pointer::offset`].
#[cfg(not(bootstrap))]
#[must_use = "returns a new pointer rather than modifying its argument"]
#[rustc_const_stable(feature = "const_ptr_offset", since = "1.61.0")]
#[rustc_nounwind]
pub fn offset<Ptr, Delta>(dst: Ptr, offset: Delta) -> Ptr;

/// The bootstrap version of this is more restricted.
#[cfg(bootstrap)]
#[must_use = "returns a new pointer rather than modifying its argument"]
#[rustc_const_stable(feature = "const_ptr_offset", since = "1.61.0")]
#[rustc_nounwind]
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10 changes: 9 additions & 1 deletion library/core/src/ptr/const_ptr.rs
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Expand Up @@ -916,8 +916,16 @@ impl<T: ?Sized> *const T {
where
T: Sized,
{
#[cfg(bootstrap)]
// SAFETY: the caller must uphold the safety contract for `offset`.
unsafe { self.offset(count as isize) }
unsafe {
self.offset(count as isize)
}
#[cfg(not(bootstrap))]
// SAFETY: the caller must uphold the safety contract for `offset`.
unsafe {
intrinsics::offset(self, count)
}
}

/// Calculates the offset from a pointer in bytes (convenience for `.byte_offset(count as isize)`).
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22 changes: 20 additions & 2 deletions library/core/src/ptr/mut_ptr.rs
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Expand Up @@ -473,10 +473,20 @@ impl<T: ?Sized> *mut T {
where
T: Sized,
{
#[cfg(bootstrap)]
// SAFETY: the caller must uphold the safety contract for `offset`.
// The obtained pointer is valid for writes since the caller must
// guarantee that it points to the same allocated object as `self`.
unsafe { intrinsics::offset(self, count) as *mut T }
unsafe {
intrinsics::offset(self, count) as *mut T
}
#[cfg(not(bootstrap))]
// SAFETY: the caller must uphold the safety contract for `offset`.
// The obtained pointer is valid for writes since the caller must
// guarantee that it points to the same allocated object as `self`.
unsafe {
intrinsics::offset(self, count)
}
}

/// Calculates the offset from a pointer in bytes.
Expand Down Expand Up @@ -1016,8 +1026,16 @@ impl<T: ?Sized> *mut T {
where
T: Sized,
{
#[cfg(bootstrap)]
// SAFETY: the caller must uphold the safety contract for `offset`.
unsafe {
self.offset(count as isize)
}
#[cfg(not(bootstrap))]
// SAFETY: the caller must uphold the safety contract for `offset`.
unsafe { self.offset(count as isize) }
unsafe {
intrinsics::offset(self, count)
}
}

/// Calculates the offset from a pointer in bytes (convenience for `.byte_offset(count as isize)`).
Expand Down
2 changes: 1 addition & 1 deletion src/doc/unstable-book/src/language-features/intrinsics.md
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@ via a declaration like
extern "rust-intrinsic" {
fn transmute<T, U>(x: T) -> U;

fn offset<T>(dst: *const T, offset: isize) -> *const T;
fn arith_offset<T>(dst: *const T, offset: isize) -> *const T;
}
```

Expand Down
34 changes: 34 additions & 0 deletions tests/codegen/intrinsics/offset.rs
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@@ -0,0 +1,34 @@
// compile-flags: -O -C no-prepopulate-passes
// min-llvm-version: 15.0 (because we're using opaque pointers)

#![crate_type = "lib"]
#![feature(core_intrinsics)]

use std::intrinsics::offset;

// CHECK-LABEL: ptr @offset_zst
// CHECK-SAME: (ptr noundef %p, [[SIZE:i[0-9]+]] noundef %d)
#[no_mangle]
pub unsafe fn offset_zst(p: *const (), d: usize) -> *const () {
// CHECK-NOT: getelementptr
// CHECK: ret ptr %p
offset(p, d)
}

// CHECK-LABEL: ptr @offset_isize
// CHECK-SAME: (ptr noundef %p, [[SIZE]] noundef %d)
#[no_mangle]
pub unsafe fn offset_isize(p: *const u32, d: isize) -> *const u32 {
// CHECK: %[[R:.*]] = getelementptr inbounds i32, ptr %p, [[SIZE]] %d
// CHECK-NEXT: ret ptr %[[R]]
offset(p, d)
}

// CHECK-LABEL: ptr @offset_usize
// CHECK-SAME: (ptr noundef %p, [[SIZE]] noundef %d)
#[no_mangle]
pub unsafe fn offset_usize(p: *const u64, d: usize) -> *const u64 {
// CHECK: %[[R:.*]] = getelementptr inbounds i64, ptr %p, [[SIZE]] %d
// CHECK-NEXT: ret ptr %[[R]]
offset(p, d)
}
4 changes: 2 additions & 2 deletions tests/mir-opt/lower_intrinsics.ptr_offset.LowerIntrinsics.diff
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Expand Up @@ -13,10 +13,10 @@
_3 = _1; // scope 0 at $DIR/lower_intrinsics.rs:+1:30: +1:31
StorageLive(_4); // scope 0 at $DIR/lower_intrinsics.rs:+1:33: +1:34
_4 = _2; // scope 0 at $DIR/lower_intrinsics.rs:+1:33: +1:34
- _0 = offset::<i32>(move _3, move _4) -> [return: bb1, unwind unreachable]; // scope 0 at $DIR/lower_intrinsics.rs:+1:5: +1:35
- _0 = offset::<*const i32, isize>(move _3, move _4) -> [return: bb1, unwind unreachable]; // scope 0 at $DIR/lower_intrinsics.rs:+1:5: +1:35
- // mir::Constant
- // + span: $DIR/lower_intrinsics.rs:140:5: 140:29
- // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(*const i32, isize) -> *const i32 {offset::<i32>}, val: Value(<ZST>) }
- // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(*const i32, isize) -> *const i32 {offset::<*const i32, isize>}, val: Value(<ZST>) }
+ _0 = Offset(move _3, move _4); // scope 0 at $DIR/lower_intrinsics.rs:+1:5: +1:35
+ goto -> bb1; // scope 0 at $DIR/lower_intrinsics.rs:+1:5: +1:35
}
Expand Down
20 changes: 1 addition & 19 deletions tests/mir-opt/pre-codegen/slice_index.slice_get_mut_usize.PreCodegen.after.mir
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Original file line number Diff line number Diff line change
Expand Up @@ -45,16 +45,7 @@ fn slice_get_mut_usize(_1: &mut [u32], _2: usize) -> Option<&mut u32> {
scope 12 (inlined ptr::mut_ptr::<impl *mut u32>::add) { // at $SRC_DIR/core/src/slice/index.rs:LL:COL
debug self => _9; // in scope 12 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
debug count => _2; // in scope 12 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
let mut _13: isize; // in scope 12 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
scope 13 {
scope 14 (inlined ptr::mut_ptr::<impl *mut u32>::offset) { // at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
debug self => _9; // in scope 14 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
debug count => _13; // in scope 14 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
let mut _14: *const u32; // in scope 14 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
let mut _15: *const u32; // in scope 14 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
scope 15 {
}
}
}
}
}
Expand Down Expand Up @@ -86,16 +77,7 @@ fn slice_get_mut_usize(_1: &mut [u32], _2: usize) -> Option<&mut u32> {
StorageLive(_12); // scope 3 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageLive(_9); // scope 6 at $SRC_DIR/core/src/slice/index.rs:LL:COL
_9 = _8 as *mut u32 (PtrToPtr); // scope 11 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageLive(_13); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
_13 = _2 as isize (IntToInt); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageLive(_14); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageLive(_15); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
_15 = _9 as *const u32 (Pointer(MutToConstPointer)); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
_14 = Offset(move _15, _13); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageDead(_15); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
_7 = move _14 as *mut u32 (PtrToPtr); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageDead(_14); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageDead(_13); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
_7 = Offset(_9, _2); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageDead(_9); // scope 6 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageDead(_12); // scope 3 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageDead(_11); // scope 3 at $SRC_DIR/core/src/slice/index.rs:LL:COL
Expand Down
72 changes: 27 additions & 45 deletions tests/mir-opt/pre-codegen/slice_index.slice_get_unchecked_mut_range.PreCodegen.after.mir
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Original file line number Diff line number Diff line change
Expand Up @@ -34,32 +34,23 @@ fn slice_get_unchecked_mut_range(_1: &mut [u32], _2: std::ops::Range<usize>) ->
scope 12 (inlined ptr::mut_ptr::<impl *mut u32>::add) { // at $SRC_DIR/core/src/slice/index.rs:LL:COL
debug self => _10; // in scope 12 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
debug count => _11; // in scope 12 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
let mut _16: isize; // in scope 12 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
scope 13 {
scope 14 (inlined ptr::mut_ptr::<impl *mut u32>::offset) { // at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
debug self => _10; // in scope 14 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
debug count => _16; // in scope 14 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
let mut _17: *const u32; // in scope 14 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
let mut _18: *const u32; // in scope 14 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
scope 15 {
}
}
}
}
scope 16 (inlined slice_from_raw_parts_mut::<u32>) { // at $SRC_DIR/core/src/slice/index.rs:LL:COL
debug data => _9; // in scope 16 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
debug len => _12; // in scope 16 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
let mut _19: *mut (); // in scope 16 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
scope 17 (inlined ptr::mut_ptr::<impl *mut u32>::cast::<()>) { // at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
debug self => _9; // in scope 17 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
scope 14 (inlined slice_from_raw_parts_mut::<u32>) { // at $SRC_DIR/core/src/slice/index.rs:LL:COL
debug data => _9; // in scope 14 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
debug len => _12; // in scope 14 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
let mut _16: *mut (); // in scope 14 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
scope 15 (inlined ptr::mut_ptr::<impl *mut u32>::cast::<()>) { // at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
debug self => _9; // in scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
}
scope 18 (inlined std::ptr::from_raw_parts_mut::<[u32]>) { // at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
debug data_address => _19; // in scope 18 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
debug metadata => _12; // in scope 18 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
let mut _20: std::ptr::metadata::PtrRepr<[u32]>; // in scope 18 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
let mut _21: std::ptr::metadata::PtrComponents<[u32]>; // in scope 18 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
let mut _22: *const (); // in scope 18 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
scope 19 {
scope 16 (inlined std::ptr::from_raw_parts_mut::<[u32]>) { // at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
debug data_address => _16; // in scope 16 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
debug metadata => _12; // in scope 16 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
let mut _17: std::ptr::metadata::PtrRepr<[u32]>; // in scope 16 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
let mut _18: std::ptr::metadata::PtrComponents<[u32]>; // in scope 16 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
let mut _19: *const (); // in scope 16 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
scope 17 {
}
}
}
Expand Down Expand Up @@ -110,33 +101,24 @@ fn slice_get_unchecked_mut_range(_1: &mut [u32], _2: std::ops::Range<usize>) ->
_10 = _4 as *mut u32 (PtrToPtr); // scope 11 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageLive(_11); // scope 6 at $SRC_DIR/core/src/slice/index.rs:LL:COL
_11 = (_2.0: usize); // scope 6 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageLive(_16); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
_16 = _11 as isize (IntToInt); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageLive(_17); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageLive(_18); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
_18 = _10 as *const u32 (Pointer(MutToConstPointer)); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
_17 = Offset(move _18, _16); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageDead(_18); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
_9 = move _17 as *mut u32 (PtrToPtr); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageDead(_17); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageDead(_16); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
_9 = Offset(_10, _11); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageDead(_11); // scope 6 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageDead(_10); // scope 6 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageLive(_12); // scope 6 at $SRC_DIR/core/src/slice/index.rs:LL:COL
_12 = _6; // scope 6 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageLive(_19); // scope 16 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
_19 = _9 as *mut () (PtrToPtr); // scope 17 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageLive(_20); // scope 19 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
StorageLive(_21); // scope 19 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
StorageLive(_22); // scope 19 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
_22 = _19 as *const () (Pointer(MutToConstPointer)); // scope 19 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
_21 = ptr::metadata::PtrComponents::<[u32]> { data_address: move _22, metadata: _12 }; // scope 19 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
StorageDead(_22); // scope 19 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
_20 = ptr::metadata::PtrRepr::<[u32]> { const_ptr: move _21 }; // scope 19 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
StorageDead(_21); // scope 19 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
_3 = (_20.1: *mut [u32]); // scope 19 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
StorageDead(_20); // scope 18 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
StorageDead(_19); // scope 16 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
StorageLive(_16); // scope 14 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
_16 = _9 as *mut () (PtrToPtr); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageLive(_17); // scope 17 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
StorageLive(_18); // scope 17 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
StorageLive(_19); // scope 17 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
_19 = _16 as *const () (Pointer(MutToConstPointer)); // scope 17 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
_18 = ptr::metadata::PtrComponents::<[u32]> { data_address: move _19, metadata: _12 }; // scope 17 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
StorageDead(_19); // scope 17 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
_17 = ptr::metadata::PtrRepr::<[u32]> { const_ptr: move _18 }; // scope 17 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
StorageDead(_18); // scope 17 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
_3 = (_17.1: *mut [u32]); // scope 17 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
StorageDead(_17); // scope 16 at $SRC_DIR/core/src/ptr/metadata.rs:LL:COL
StorageDead(_16); // scope 14 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
StorageDead(_12); // scope 6 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageDead(_9); // scope 6 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageDead(_6); // scope 5 at $SRC_DIR/core/src/slice/index.rs:LL:COL
Expand Down
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