tests/mir-opt/pre-codegen/slice_iter.slice_iter_mut_next_back.PreCodegen.after.panic-unwind.mir

// MIR for `slice_iter_mut_next_back` after PreCodegen

fn slice_iter_mut_next_back(_1: &mut std::slice::IterMut<'_, T>) -> Option<&mut T> {
    debug it => _1;
    let mut _0: std::option::Option<&mut T>;
    scope 1 (inlined <std::slice::IterMut<'_, T> as DoubleEndedIterator>::next_back) {
        let mut _2: *mut T;
        let mut _7: bool;
        let mut _8: *mut T;
        let mut _21: &mut T;
        scope 2 {
            let _3: std::ptr::NonNull<T>;
            let _9: usize;
            scope 3 {
            }
            scope 4 {
                scope 7 (inlined <NonNull<T> as PartialEq>::eq) {
                    let mut _4: std::ptr::NonNull<T>;
                    let mut _5: *mut T;
                    let mut _6: *mut T;
                    scope 8 (inlined NonNull::<T>::as_ptr) {
                    }
                    scope 9 (inlined NonNull::<T>::as_ptr) {
                    }
                }
            }
            scope 5 (inlined std::ptr::mut_ptr::<impl *mut T>::addr) {
                scope 6 (inlined std::ptr::mut_ptr::<impl *mut T>::cast::<()>) {
                }
            }
        }
        scope 10 (inlined std::slice::IterMut::<'_, T>::next_back_unchecked) {
            let mut _15: std::ptr::NonNull<T>;
            scope 11 (inlined std::slice::IterMut::<'_, T>::pre_dec_end) {
                let mut _10: *mut *mut T;
                let mut _11: *mut std::ptr::NonNull<T>;
                let mut _12: std::ptr::NonNull<T>;
                let mut _16: *mut *mut T;
                let mut _17: *mut usize;
                let mut _18: usize;
                let mut _19: usize;
                scope 12 {
                    scope 13 {
                    }
                    scope 14 {
                        scope 17 (inlined NonNull::<T>::sub) {
                            scope 18 (inlined #[track_caller] core::num::<impl isize>::unchecked_neg) {
                                scope 19 (inlined core::ub_checks::check_language_ub) {
                                    scope 20 (inlined core::ub_checks::check_language_ub::runtime) {
                                    }
                                }
                            }
                            scope 21 (inlined NonNull::<T>::offset) {
                                let mut _13: *const T;
                                let mut _14: *const T;
                                scope 22 (inlined NonNull::<T>::as_ptr) {
                                }
                            }
                        }
                    }
                    scope 15 (inlined std::ptr::mut_ptr::<impl *mut *mut T>::cast::<usize>) {
                    }
                    scope 16 (inlined std::ptr::mut_ptr::<impl *mut *mut T>::cast::<NonNull<T>>) {
                    }
                }
            }
            scope 23 (inlined NonNull::<T>::as_mut::<'_>) {
                let mut _20: *mut T;
                scope 24 (inlined NonNull::<T>::as_ptr) {
                }
            }
        }
    }

    bb0: {
        StorageLive(_9);
        StorageLive(_8);
        StorageLive(_3);
        StorageLive(_2);
        StorageLive(_21);
        StorageLive(_7);
        switchInt(const <T as std::mem::SizedTypeProperties>::IS_ZST) -> [0: bb1, otherwise: bb2];
    }

    bb1: {
        _2 = copy ((*_1).1: *mut T);
        _3 = copy _2 as std::ptr::NonNull<T> (Transmute);
        StorageLive(_5);
        StorageLive(_4);
        _4 = copy ((*_1).0: std::ptr::NonNull<T>);
        _5 = copy _4 as *mut T (Transmute);
        StorageDead(_4);
        StorageLive(_6);
        _6 = copy _3 as *mut T (Transmute);
        _7 = Eq(copy _5, copy _6);
        StorageDead(_6);
        StorageDead(_5);
        goto -> bb3;
    }

    bb2: {
        _8 = copy ((*_1).1: *mut T);
        _9 = copy _8 as usize (Transmute);
        _7 = Eq(copy _9, const 0_usize);
        goto -> bb3;
    }

    bb3: {
        switchInt(move _7) -> [0: bb4, otherwise: bb10];
    }

    bb4: {
        StorageLive(_15);
        StorageLive(_17);
        StorageLive(_11);
        StorageLive(_12);
        switchInt(const <T as std::mem::SizedTypeProperties>::IS_ZST) -> [0: bb5, otherwise: bb8];
    }

    bb5: {
        StorageLive(_10);
        _10 = &raw mut ((*_1).1: *mut T);
        _11 = copy _10 as *mut std::ptr::NonNull<T> (PtrToPtr);
        StorageDead(_10);
        _12 = copy (*_11);
        switchInt(const <T as std::mem::SizedTypeProperties>::IS_ZST) -> [0: bb6, otherwise: bb7];
    }

    bb6: {
        StorageLive(_14);
        StorageLive(_13);
        _13 = copy _12 as *const T (Transmute);
        _14 = Offset(copy _13, const -1_isize);
        StorageDead(_13);
        _12 = NonNull::<T> { pointer: copy _14 };
        StorageDead(_14);
        goto -> bb7;
    }

    bb7: {
        (*_11) = move _12;
        _15 = copy (*_11);
        goto -> bb9;
    }

    bb8: {
        StorageLive(_16);
        _16 = &raw mut ((*_1).1: *mut T);
        _17 = copy _16 as *mut usize (PtrToPtr);
        StorageDead(_16);
        StorageLive(_19);
        StorageLive(_18);
        _18 = copy (*_17);
        _19 = SubUnchecked(move _18, const 1_usize);
        StorageDead(_18);
        (*_17) = move _19;
        StorageDead(_19);
        _15 = copy ((*_1).0: std::ptr::NonNull<T>);
        goto -> bb9;
    }

    bb9: {
        StorageDead(_12);
        StorageDead(_11);
        StorageDead(_17);
        StorageLive(_20);
        _20 = copy _15 as *mut T (Transmute);
        _21 = &mut (*_20);
        StorageDead(_20);
        StorageDead(_15);
        _0 = Option::<&mut T>::Some(copy _21);
        goto -> bb11;
    }

    bb10: {
        _0 = const {transmute(0x0000000000000000): Option<&mut T>};
        goto -> bb11;
    }

    bb11: {
        StorageDead(_7);
        StorageDead(_21);
        StorageDead(_2);
        StorageDead(_3);
        StorageDead(_8);
        StorageDead(_9);
        return;
    }
}