Save another BB by using `SubUnchecked` instead of a call to `arith_offset`

Probably reasonable anyway since it more obviously drops provenance.

5 files changed, 251 insertions, 315 deletions

diff --git a/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-abort.mir b/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-abort.mir
index e12f97073d0..80b96e01041 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-abort.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-abort.mir
@@ -7,27 +7,27 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
     let mut _11: std::ptr::NonNull<T>;
     let mut _12: *const T;
     let mut _13: usize;
-    let mut _33: std::option::Option<(usize, &T)>;
-    let mut _36: &impl Fn(usize, &T);
-    let mut _37: (usize, &T);
-    let _38: ();
+    let mut _31: std::option::Option<(usize, &T)>;
+    let mut _34: &impl Fn(usize, &T);
+    let mut _35: (usize, &T);
+    let _36: ();
     scope 1 {
         debug (((iter: Enumerate<std::slice::Iter<'_, T>>).0: std::slice::Iter<'_, T>).0: std::ptr::NonNull<T>) => _11;
         debug (((iter: Enumerate<std::slice::Iter<'_, T>>).0: std::slice::Iter<'_, T>).1: *const T) => _12;
         debug (((iter: Enumerate<std::slice::Iter<'_, T>>).0: std::slice::Iter<'_, T>).2: std::marker::PhantomData<&T>) => const ZeroSized: PhantomData<&T>;
         debug ((iter: Enumerate<std::slice::Iter<'_, T>>).1: usize) => _13;
-        let _34: usize;
-        let _35: &T;
+        let _32: usize;
+        let _33: &T;
         scope 2 {
-            debug i => _34;
-            debug x => _35;
+            debug i => _32;
+            debug x => _33;
         }
         scope 19 (inlined <Enumerate<std::slice::Iter<'_, T>> as Iterator>::next) {
-            let mut _27: std::option::Option<&T>;
-            let mut _31: (usize, bool);
-            let mut _32: (usize, &T);
+            let mut _25: std::option::Option<&T>;
+            let mut _29: (usize, bool);
+            let mut _30: (usize, &T);
             scope 20 {
-                let _30: usize;
+                let _28: usize;
                 scope 25 {
                 }
             }
@@ -42,8 +42,8 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
                 }
             }
             scope 26 (inlined <Option<&T> as Try>::branch) {
-                let mut _28: isize;
-                let _29: &T;
+                let mut _26: isize;
+                let _27: &T;
                 scope 27 {
                 }
             }
@@ -52,43 +52,37 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
                 let _16: std::ptr::NonNull<T>;
                 let mut _19: bool;
                 let mut _22: std::ptr::NonNull<T>;
-                let mut _24: bool;
-                let mut _25: *const u8;
-                let mut _26: *const T;
+                let mut _24: usize;
                 scope 30 {
                     let _15: *const T;
                     scope 31 {
-                        let _23: *const u8;
+                        let _23: usize;
                         scope 32 {
-                            scope 33 (inlined null::<u8>) {
-                                scope 34 (inlined without_provenance::<()>) {
-                                    scope 35 (inlined without_provenance_mut::<()>) {
+                            scope 35 (inlined core::num::<impl usize>::unchecked_sub) {
+                                scope 36 (inlined core::ub_checks::check_language_ub) {
+                                    scope 37 (inlined core::ub_checks::check_language_ub::runtime) {
                                     }
                                 }
-                                scope 36 (inlined std::ptr::from_raw_parts::<u8, ()>) {
-                                }
                             }
-                            scope 37 (inlined std::ptr::const_ptr::<impl *const u8>::wrapping_sub) {
-                                scope 38 (inlined core::num::<impl isize>::wrapping_neg) {
-                                    scope 39 (inlined core::num::<impl isize>::wrapping_sub) {
-                                    }
-                                }
-                                scope 40 (inlined std::ptr::const_ptr::<impl *const u8>::wrapping_offset) {
-                                }
+                            scope 38 (inlined without_provenance_mut::<T>) {
                             }
                         }
-                        scope 41 (inlined <NonNull<T> as PartialEq>::eq) {
+                        scope 33 (inlined std::ptr::const_ptr::<impl *const T>::addr) {
+                            scope 34 (inlined std::ptr::const_ptr::<impl *const T>::cast::<()>) {
+                            }
+                        }
+                        scope 39 (inlined <NonNull<T> as PartialEq>::eq) {
                             let mut _17: *mut T;
                             let mut _18: *mut T;
-                            scope 42 (inlined NonNull::<T>::as_ptr) {
+                            scope 40 (inlined NonNull::<T>::as_ptr) {
                             }
-                            scope 43 (inlined NonNull::<T>::as_ptr) {
+                            scope 41 (inlined NonNull::<T>::as_ptr) {
                             }
                         }
-                        scope 44 (inlined NonNull::<T>::add) {
+                        scope 42 (inlined NonNull::<T>::add) {
                             let mut _20: *const T;
                             let mut _21: *const T;
-                            scope 45 (inlined NonNull::<T>::as_ptr) {
+                            scope 43 (inlined NonNull::<T>::as_ptr) {
                             }
                         }
                     }
@@ -181,13 +175,14 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
     }
 
     bb4: {
-        StorageLive(_33);
-        StorageLive(_30);
         StorageLive(_31);
-        StorageLive(_27);
+        StorageLive(_28);
+        StorageLive(_29);
+        StorageLive(_25);
         StorageLive(_14);
         StorageLive(_15);
         StorageLive(_23);
+        StorageLive(_24);
         StorageLive(_16);
         _14 = copy _11;
         _15 = copy _12;
@@ -225,104 +220,97 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
     bb7: {
         StorageDead(_19);
         StorageDead(_16);
+        StorageDead(_24);
         StorageDead(_23);
         StorageDead(_15);
         StorageDead(_14);
-        StorageLive(_28);
-        goto -> bb17;
+        StorageLive(_26);
+        goto -> bb12;
     }
 
     bb8: {
-        _23 = copy _15 as *const u8 (PtrToPtr);
-        StorageLive(_24);
-        _24 = Eq(copy _23, const {0x0 as *const u8});
-        switchInt(move _24) -> [0: bb9, otherwise: bb16];
+        _23 = copy _15 as usize (Transmute);
+        switchInt(copy _23) -> [0: bb9, otherwise: bb10];
     }
 
     bb9: {
+        StorageDead(_16);
         StorageDead(_24);
-        StorageLive(_25);
-        _25 = arith_offset::<u8>(move _23, const -1_isize) -> [return: bb10, unwind unreachable];
+        StorageDead(_23);
+        StorageDead(_15);
+        StorageDead(_14);
+        StorageLive(_26);
+        goto -> bb12;
     }
 
     bb10: {
-        _26 = move _25 as *const T (PtrToPtr);
-        StorageDead(_25);
-        _12 = copy _26;
+        _24 = SubUnchecked(copy _23, const 1_usize);
+        _12 = copy _24 as *const T (Transmute);
         goto -> bb11;
     }
 
     bb11: {
-        _27 = copy _14 as std::option::Option<&T> (Transmute);
+        _25 = copy _14 as std::option::Option<&T> (Transmute);
         StorageDead(_16);
+        StorageDead(_24);
         StorageDead(_23);
         StorageDead(_15);
         StorageDead(_14);
-        StorageLive(_28);
-        _28 = discriminant(_27);
-        switchInt(move _28) -> [0: bb17, 1: bb12, otherwise: bb15];
+        StorageLive(_26);
+        _26 = discriminant(_25);
+        switchInt(move _26) -> [0: bb12, 1: bb14, otherwise: bb17];
     }
 
     bb12: {
-        _29 = move ((_27 as Some).0: &T);
+        StorageDead(_26);
+        StorageDead(_25);
+        StorageDead(_29);
         StorageDead(_28);
-        StorageDead(_27);
-        _30 = copy _13;
-        _31 = AddWithOverflow(copy _13, const 1_usize);
-        assert(!move (_31.1: bool), "attempt to compute `{} + {}`, which would overflow", copy _13, const 1_usize) -> [success: bb13, unwind unreachable];
+        StorageDead(_31);
+        StorageDead(_11);
+        StorageDead(_12);
+        StorageDead(_13);
+        drop(_2) -> [return: bb13, unwind unreachable];
     }
 
     bb13: {
-        _13 = move (_31.0: usize);
-        StorageLive(_32);
-        _32 = (copy _30, copy _29);
-        _33 = Option::<(usize, &T)>::Some(move _32);
-        StorageDead(_32);
-        StorageDead(_31);
-        StorageDead(_30);
-        _34 = copy (((_33 as Some).0: (usize, &T)).0: usize);
-        _35 = copy (((_33 as Some).0: (usize, &T)).1: &T);
-        StorageLive(_36);
-        _36 = &_2;
-        StorageLive(_37);
-        _37 = (copy _34, copy _35);
-        _38 = <impl Fn(usize, &T) as Fn<(usize, &T)>>::call(move _36, move _37) -> [return: bb14, unwind unreachable];
+        return;
     }
 
     bb14: {
-        StorageDead(_37);
-        StorageDead(_36);
-        StorageDead(_33);
-        goto -> bb4;
+        _27 = move ((_25 as Some).0: &T);
+        StorageDead(_26);
+        StorageDead(_25);
+        _28 = copy _13;
+        _29 = AddWithOverflow(copy _13, const 1_usize);
+        assert(!move (_29.1: bool), "attempt to compute `{} + {}`, which would overflow", copy _13, const 1_usize) -> [success: bb15, unwind unreachable];
     }
 
     bb15: {
-        unreachable;
+        _13 = move (_29.0: usize);
+        StorageLive(_30);
+        _30 = (copy _28, copy _27);
+        _31 = Option::<(usize, &T)>::Some(move _30);
+        StorageDead(_30);
+        StorageDead(_29);
+        StorageDead(_28);
+        _32 = copy (((_31 as Some).0: (usize, &T)).0: usize);
+        _33 = copy (((_31 as Some).0: (usize, &T)).1: &T);
+        StorageLive(_34);
+        _34 = &_2;
+        StorageLive(_35);
+        _35 = (copy _32, copy _33);
+        _36 = <impl Fn(usize, &T) as Fn<(usize, &T)>>::call(move _34, move _35) -> [return: bb16, unwind unreachable];
     }
 
     bb16: {
-        StorageDead(_24);
-        StorageDead(_16);
-        StorageDead(_23);
-        StorageDead(_15);
-        StorageDead(_14);
-        StorageLive(_28);
-        goto -> bb17;
-    }
-
-    bb17: {
-        StorageDead(_28);
-        StorageDead(_27);
+        StorageDead(_35);
+        StorageDead(_34);
         StorageDead(_31);
-        StorageDead(_30);
-        StorageDead(_33);
-        StorageDead(_11);
-        StorageDead(_12);
-        StorageDead(_13);
-        drop(_2) -> [return: bb18, unwind unreachable];
+        goto -> bb4;
     }
 
-    bb18: {
-        return;
+    bb17: {
+        unreachable;
     }
 }
diff --git a/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-abort.mir b/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-abort.mir
index 88d0aa7f624..c539170055d 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-abort.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-abort.mir
@@ -6,61 +6,55 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     let mut _0: ();
     let mut _11: std::ptr::NonNull<T>;
     let mut _12: *const T;
-    let mut _26: std::option::Option<&T>;
-    let mut _27: isize;
-    let mut _29: &impl Fn(&T);
-    let mut _30: (&T,);
-    let _31: ();
+    let mut _24: std::option::Option<&T>;
+    let mut _25: isize;
+    let mut _27: &impl Fn(&T);
+    let mut _28: (&T,);
+    let _29: ();
     scope 1 {
         debug ((iter: std::slice::Iter<'_, T>).0: std::ptr::NonNull<T>) => _11;
         debug ((iter: std::slice::Iter<'_, T>).1: *const T) => _12;
         debug ((iter: std::slice::Iter<'_, T>).2: std::marker::PhantomData<&T>) => const ZeroSized: PhantomData<&T>;
-        let _28: &T;
+        let _26: &T;
         scope 2 {
-            debug x => _28;
+            debug x => _26;
         }
         scope 17 (inlined <std::slice::Iter<'_, T> as Iterator>::next) {
             let _13: std::ptr::NonNull<T>;
             let _15: std::ptr::NonNull<T>;
             let mut _18: bool;
             let mut _21: std::ptr::NonNull<T>;
-            let mut _23: bool;
-            let mut _24: *const u8;
-            let mut _25: *const T;
+            let mut _23: usize;
             scope 18 {
                 let _14: *const T;
                 scope 19 {
-                    let _22: *const u8;
+                    let _22: usize;
                     scope 20 {
-                        scope 21 (inlined null::<u8>) {
-                            scope 22 (inlined without_provenance::<()>) {
-                                scope 23 (inlined without_provenance_mut::<()>) {
+                        scope 23 (inlined core::num::<impl usize>::unchecked_sub) {
+                            scope 24 (inlined core::ub_checks::check_language_ub) {
+                                scope 25 (inlined core::ub_checks::check_language_ub::runtime) {
                                 }
                             }
-                            scope 24 (inlined std::ptr::from_raw_parts::<u8, ()>) {
-                            }
                         }
-                        scope 25 (inlined std::ptr::const_ptr::<impl *const u8>::wrapping_sub) {
-                            scope 26 (inlined core::num::<impl isize>::wrapping_neg) {
-                                scope 27 (inlined core::num::<impl isize>::wrapping_sub) {
-                                }
-                            }
-                            scope 28 (inlined std::ptr::const_ptr::<impl *const u8>::wrapping_offset) {
-                            }
+                        scope 26 (inlined without_provenance_mut::<T>) {
+                        }
+                    }
+                    scope 21 (inlined std::ptr::const_ptr::<impl *const T>::addr) {
+                        scope 22 (inlined std::ptr::const_ptr::<impl *const T>::cast::<()>) {
                         }
                     }
-                    scope 29 (inlined <NonNull<T> as PartialEq>::eq) {
+                    scope 27 (inlined <NonNull<T> as PartialEq>::eq) {
                         let mut _16: *mut T;
                         let mut _17: *mut T;
-                        scope 30 (inlined NonNull::<T>::as_ptr) {
+                        scope 28 (inlined NonNull::<T>::as_ptr) {
                         }
-                        scope 31 (inlined NonNull::<T>::as_ptr) {
+                        scope 29 (inlined NonNull::<T>::as_ptr) {
                         }
                     }
-                    scope 32 (inlined NonNull::<T>::add) {
+                    scope 30 (inlined NonNull::<T>::add) {
                         let mut _19: *const T;
                         let mut _20: *const T;
-                        scope 33 (inlined NonNull::<T>::as_ptr) {
+                        scope 31 (inlined NonNull::<T>::as_ptr) {
                         }
                     }
                 }
@@ -146,10 +140,11 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     }
 
     bb4: {
-        StorageLive(_26);
+        StorageLive(_24);
         StorageLive(_13);
         StorageLive(_14);
         StorageLive(_22);
+        StorageLive(_23);
         StorageLive(_15);
         _13 = copy _11;
         _14 = copy _12;
@@ -187,79 +182,72 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     bb7: {
         StorageDead(_18);
         StorageDead(_15);
+        StorageDead(_23);
         StorageDead(_22);
         StorageDead(_14);
         StorageDead(_13);
-        goto -> bb16;
+        goto -> bb12;
     }
 
     bb8: {
-        _22 = copy _14 as *const u8 (PtrToPtr);
-        StorageLive(_23);
-        _23 = Eq(copy _22, const {0x0 as *const u8});
-        switchInt(move _23) -> [0: bb9, otherwise: bb15];
+        _22 = copy _14 as usize (Transmute);
+        switchInt(copy _22) -> [0: bb9, otherwise: bb10];
     }
 
     bb9: {
+        StorageDead(_15);
         StorageDead(_23);
-        StorageLive(_24);
-        _24 = arith_offset::<u8>(move _22, const -1_isize) -> [return: bb10, unwind unreachable];
+        StorageDead(_22);
+        StorageDead(_14);
+        StorageDead(_13);
+        goto -> bb12;
     }
 
     bb10: {
-        _25 = move _24 as *const T (PtrToPtr);
-        StorageDead(_24);
-        _12 = copy _25;
+        _23 = SubUnchecked(copy _22, const 1_usize);
+        _12 = copy _23 as *const T (Transmute);
         goto -> bb11;
     }
 
     bb11: {
-        _26 = copy _13 as std::option::Option<&T> (Transmute);
+        _24 = copy _13 as std::option::Option<&T> (Transmute);
         StorageDead(_15);
+        StorageDead(_23);
         StorageDead(_22);
         StorageDead(_14);
         StorageDead(_13);
-        _27 = discriminant(_26);
-        switchInt(move _27) -> [0: bb16, 1: bb12, otherwise: bb14];
+        _25 = discriminant(_24);
+        switchInt(move _25) -> [0: bb12, 1: bb14, otherwise: bb16];
     }
 
     bb12: {
-        _28 = copy ((_26 as Some).0: &T);
-        StorageLive(_29);
-        _29 = &_2;
-        StorageLive(_30);
-        _30 = (copy _28,);
-        _31 = <impl Fn(&T) as Fn<(&T,)>>::call(move _29, move _30) -> [return: bb13, unwind unreachable];
+        StorageDead(_24);
+        StorageDead(_11);
+        StorageDead(_12);
+        drop(_2) -> [return: bb13, unwind unreachable];
     }
 
     bb13: {
-        StorageDead(_30);
-        StorageDead(_29);
-        StorageDead(_26);
-        goto -> bb4;
+        return;
     }
 
     bb14: {
-        unreachable;
+        _26 = copy ((_24 as Some).0: &T);
+        StorageLive(_27);
+        _27 = &_2;
+        StorageLive(_28);
+        _28 = (copy _26,);
+        _29 = <impl Fn(&T) as Fn<(&T,)>>::call(move _27, move _28) -> [return: bb15, unwind unreachable];
     }
 
     bb15: {
-        StorageDead(_23);
-        StorageDead(_15);
-        StorageDead(_22);
-        StorageDead(_14);
-        StorageDead(_13);
-        goto -> bb16;
+        StorageDead(_28);
+        StorageDead(_27);
+        StorageDead(_24);
+        goto -> bb4;
     }
 
     bb16: {
-        StorageDead(_26);
-        StorageDead(_11);
-        StorageDead(_12);
-        drop(_2) -> [return: bb17, unwind unreachable];
-    }
-
-    bb17: {
-        return;
+        unreachable;
     }
 }
diff --git a/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-unwind.mir b/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-unwind.mir
index f34edc4775d..dc537ad8740 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-unwind.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-unwind.mir
@@ -6,61 +6,55 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     let mut _0: ();
     let mut _11: std::ptr::NonNull<T>;
     let mut _12: *const T;
-    let mut _26: std::option::Option<&T>;
-    let mut _27: isize;
-    let mut _29: &impl Fn(&T);
-    let mut _30: (&T,);
-    let _31: ();
+    let mut _24: std::option::Option<&T>;
+    let mut _25: isize;
+    let mut _27: &impl Fn(&T);
+    let mut _28: (&T,);
+    let _29: ();
     scope 1 {
         debug ((iter: std::slice::Iter<'_, T>).0: std::ptr::NonNull<T>) => _11;
         debug ((iter: std::slice::Iter<'_, T>).1: *const T) => _12;
         debug ((iter: std::slice::Iter<'_, T>).2: std::marker::PhantomData<&T>) => const ZeroSized: PhantomData<&T>;
-        let _28: &T;
+        let _26: &T;
         scope 2 {
-            debug x => _28;
+            debug x => _26;
         }
         scope 17 (inlined <std::slice::Iter<'_, T> as Iterator>::next) {
             let _13: std::ptr::NonNull<T>;
             let _15: std::ptr::NonNull<T>;
             let mut _18: bool;
             let mut _21: std::ptr::NonNull<T>;
-            let mut _23: bool;
-            let mut _24: *const u8;
-            let mut _25: *const T;
+            let mut _23: usize;
             scope 18 {
                 let _14: *const T;
                 scope 19 {
-                    let _22: *const u8;
+                    let _22: usize;
                     scope 20 {
-                        scope 21 (inlined null::<u8>) {
-                            scope 22 (inlined without_provenance::<()>) {
-                                scope 23 (inlined without_provenance_mut::<()>) {
+                        scope 23 (inlined core::num::<impl usize>::unchecked_sub) {
+                            scope 24 (inlined core::ub_checks::check_language_ub) {
+                                scope 25 (inlined core::ub_checks::check_language_ub::runtime) {
                                 }
                             }
-                            scope 24 (inlined std::ptr::from_raw_parts::<u8, ()>) {
-                            }
                         }
-                        scope 25 (inlined std::ptr::const_ptr::<impl *const u8>::wrapping_sub) {
-                            scope 26 (inlined core::num::<impl isize>::wrapping_neg) {
-                                scope 27 (inlined core::num::<impl isize>::wrapping_sub) {
-                                }
-                            }
-                            scope 28 (inlined std::ptr::const_ptr::<impl *const u8>::wrapping_offset) {
-                            }
+                        scope 26 (inlined without_provenance_mut::<T>) {
+                        }
+                    }
+                    scope 21 (inlined std::ptr::const_ptr::<impl *const T>::addr) {
+                        scope 22 (inlined std::ptr::const_ptr::<impl *const T>::cast::<()>) {
                         }
                     }
-                    scope 29 (inlined <NonNull<T> as PartialEq>::eq) {
+                    scope 27 (inlined <NonNull<T> as PartialEq>::eq) {
                         let mut _16: *mut T;
                         let mut _17: *mut T;
-                        scope 30 (inlined NonNull::<T>::as_ptr) {
+                        scope 28 (inlined NonNull::<T>::as_ptr) {
                         }
-                        scope 31 (inlined NonNull::<T>::as_ptr) {
+                        scope 29 (inlined NonNull::<T>::as_ptr) {
                         }
                     }
-                    scope 32 (inlined NonNull::<T>::add) {
+                    scope 30 (inlined NonNull::<T>::add) {
                         let mut _19: *const T;
                         let mut _20: *const T;
-                        scope 33 (inlined NonNull::<T>::as_ptr) {
+                        scope 31 (inlined NonNull::<T>::as_ptr) {
                         }
                     }
                 }
@@ -146,10 +140,11 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     }
 
     bb4: {
-        StorageLive(_26);
+        StorageLive(_24);
         StorageLive(_13);
         StorageLive(_14);
         StorageLive(_22);
+        StorageLive(_23);
         StorageLive(_15);
         _13 = copy _11;
         _14 = copy _12;
@@ -187,87 +182,80 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
     bb7: {
         StorageDead(_18);
         StorageDead(_15);
+        StorageDead(_23);
         StorageDead(_22);
         StorageDead(_14);
         StorageDead(_13);
-        goto -> bb18;
+        goto -> bb12;
     }
 
     bb8: {
-        _22 = copy _14 as *const u8 (PtrToPtr);
-        StorageLive(_23);
-        _23 = Eq(copy _22, const {0x0 as *const u8});
-        switchInt(move _23) -> [0: bb9, otherwise: bb17];
+        _22 = copy _14 as usize (Transmute);
+        switchInt(copy _22) -> [0: bb9, otherwise: bb10];
     }
 
     bb9: {
+        StorageDead(_15);
         StorageDead(_23);
-        StorageLive(_24);
-        _24 = arith_offset::<u8>(move _22, const -1_isize) -> [return: bb10, unwind unreachable];
+        StorageDead(_22);
+        StorageDead(_14);
+        StorageDead(_13);
+        goto -> bb12;
     }
 
     bb10: {
-        _25 = move _24 as *const T (PtrToPtr);
-        StorageDead(_24);
-        _12 = copy _25;
+        _23 = SubUnchecked(copy _22, const 1_usize);
+        _12 = copy _23 as *const T (Transmute);
         goto -> bb11;
     }
 
     bb11: {
-        _26 = copy _13 as std::option::Option<&T> (Transmute);
+        _24 = copy _13 as std::option::Option<&T> (Transmute);
         StorageDead(_15);
+        StorageDead(_23);
         StorageDead(_22);
         StorageDead(_14);
         StorageDead(_13);
-        _27 = discriminant(_26);
-        switchInt(move _27) -> [0: bb18, 1: bb12, otherwise: bb16];
+        _25 = discriminant(_24);
+        switchInt(move _25) -> [0: bb12, 1: bb14, otherwise: bb18];
     }
 
     bb12: {
-        _28 = copy ((_26 as Some).0: &T);
-        StorageLive(_29);
-        _29 = &_2;
-        StorageLive(_30);
-        _30 = (copy _28,);
-        _31 = <impl Fn(&T) as Fn<(&T,)>>::call(move _29, move _30) -> [return: bb13, unwind: bb14];
+        StorageDead(_24);
+        StorageDead(_11);
+        StorageDead(_12);
+        drop(_2) -> [return: bb13, unwind continue];
     }
 
     bb13: {
-        StorageDead(_30);
-        StorageDead(_29);
-        StorageDead(_26);
-        goto -> bb4;
+        return;
     }
 
-    bb14 (cleanup): {
-        drop(_2) -> [return: bb15, unwind terminate(cleanup)];
+    bb14: {
+        _26 = copy ((_24 as Some).0: &T);
+        StorageLive(_27);
+        _27 = &_2;
+        StorageLive(_28);
+        _28 = (copy _26,);
+        _29 = <impl Fn(&T) as Fn<(&T,)>>::call(move _27, move _28) -> [return: bb15, unwind: bb16];
     }
 
-    bb15 (cleanup): {
-        resume;
+    bb15: {
+        StorageDead(_28);
+        StorageDead(_27);
+        StorageDead(_24);
+        goto -> bb4;
     }
 
-    bb16: {
-        unreachable;
+    bb16 (cleanup): {
+        drop(_2) -> [return: bb17, unwind terminate(cleanup)];
     }
 
-    bb17: {
-        StorageDead(_23);
-        StorageDead(_15);
-        StorageDead(_22);
-        StorageDead(_14);
-        StorageDead(_13);
-        goto -> bb18;
+    bb17 (cleanup): {
+        resume;
     }
 
     bb18: {
-        StorageDead(_26);
-        StorageDead(_11);
-        StorageDead(_12);
-        drop(_2) -> [return: bb19, unwind continue];
-    }
-
-    bb19: {
-        return;
+        unreachable;
     }
 }
diff --git a/tests/mir-opt/pre-codegen/slice_iter.slice_iter_next.PreCodegen.after.panic-abort.mir b/tests/mir-opt/pre-codegen/slice_iter.slice_iter_next.PreCodegen.after.panic-abort.mir
index 975a8a11fb2..0fe469c21f7 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.slice_iter_next.PreCodegen.after.panic-abort.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.slice_iter_next.PreCodegen.after.panic-abort.mir
@@ -8,43 +8,37 @@ fn slice_iter_next(_1: &mut std::slice::Iter<'_, T>) -> Option<&T> {
         let _4: std::ptr::NonNull<T>;
         let mut _7: bool;
         let mut _10: std::ptr::NonNull<T>;
-        let mut _12: bool;
-        let mut _13: *const u8;
-        let mut _14: *const T;
+        let mut _12: usize;
         scope 2 {
             let _3: *const T;
             scope 3 {
-                let _11: *const u8;
+                let _11: usize;
                 scope 4 {
-                    scope 5 (inlined null::<u8>) {
-                        scope 6 (inlined without_provenance::<()>) {
-                            scope 7 (inlined without_provenance_mut::<()>) {
+                    scope 7 (inlined core::num::<impl usize>::unchecked_sub) {
+                        scope 8 (inlined core::ub_checks::check_language_ub) {
+                            scope 9 (inlined core::ub_checks::check_language_ub::runtime) {
                             }
                         }
-                        scope 8 (inlined std::ptr::from_raw_parts::<u8, ()>) {
-                        }
                     }
-                    scope 9 (inlined std::ptr::const_ptr::<impl *const u8>::wrapping_sub) {
-                        scope 10 (inlined core::num::<impl isize>::wrapping_neg) {
-                            scope 11 (inlined core::num::<impl isize>::wrapping_sub) {
-                            }
-                        }
-                        scope 12 (inlined std::ptr::const_ptr::<impl *const u8>::wrapping_offset) {
-                        }
+                    scope 10 (inlined without_provenance_mut::<T>) {
                     }
                 }
-                scope 13 (inlined <NonNull<T> as PartialEq>::eq) {
+                scope 5 (inlined std::ptr::const_ptr::<impl *const T>::addr) {
+                    scope 6 (inlined std::ptr::const_ptr::<impl *const T>::cast::<()>) {
+                    }
+                }
+                scope 11 (inlined <NonNull<T> as PartialEq>::eq) {
                     let mut _5: *mut T;
                     let mut _6: *mut T;
-                    scope 14 (inlined NonNull::<T>::as_ptr) {
+                    scope 12 (inlined NonNull::<T>::as_ptr) {
                     }
-                    scope 15 (inlined NonNull::<T>::as_ptr) {
+                    scope 13 (inlined NonNull::<T>::as_ptr) {
                     }
                 }
-                scope 16 (inlined NonNull::<T>::add) {
+                scope 14 (inlined NonNull::<T>::add) {
                     let mut _8: *const T;
                     let mut _9: *const T;
-                    scope 17 (inlined NonNull::<T>::as_ptr) {
+                    scope 15 (inlined NonNull::<T>::as_ptr) {
                     }
                 }
             }
@@ -55,6 +49,7 @@ fn slice_iter_next(_1: &mut std::slice::Iter<'_, T>) -> Option<&T> {
         StorageLive(_2);
         StorageLive(_3);
         StorageLive(_11);
+        StorageLive(_12);
         StorageLive(_4);
         _2 = copy ((*_1).0: std::ptr::NonNull<T>);
         _3 = copy ((*_1).1: *const T);
@@ -92,42 +87,33 @@ fn slice_iter_next(_1: &mut std::slice::Iter<'_, T>) -> Option<&T> {
     bb3: {
         _0 = const {transmute(0x0000000000000000): Option<&T>};
         StorageDead(_7);
-        goto -> bb9;
+        goto -> bb8;
     }
 
     bb4: {
-        _11 = copy _3 as *const u8 (PtrToPtr);
-        StorageLive(_12);
-        _12 = Eq(copy _11, const {0x0 as *const u8});
-        switchInt(move _12) -> [0: bb5, otherwise: bb8];
+        _11 = copy _3 as usize (Transmute);
+        switchInt(copy _11) -> [0: bb5, otherwise: bb6];
     }
 
     bb5: {
-        StorageDead(_12);
-        StorageLive(_13);
-        _13 = arith_offset::<u8>(move _11, const -1_isize) -> [return: bb6, unwind unreachable];
+        _0 = const {transmute(0x0000000000000000): Option<&T>};
+        goto -> bb8;
     }
 
     bb6: {
-        _14 = move _13 as *const T (PtrToPtr);
-        StorageDead(_13);
-        ((*_1).1: *const T) = copy _14;
+        _12 = SubUnchecked(copy _11, const 1_usize);
+        ((*_1).1: *const T) = copy _12 as *const T (Transmute);
         goto -> bb7;
     }
 
     bb7: {
         _0 = copy _2 as std::option::Option<&T> (Transmute);
-        goto -> bb9;
+        goto -> bb8;
     }
 
     bb8: {
-        _0 = const {transmute(0x0000000000000000): Option<&T>};
-        StorageDead(_12);
-        goto -> bb9;
-    }
-
-    bb9: {
         StorageDead(_4);
+        StorageDead(_12);
         StorageDead(_11);
         StorageDead(_3);
         StorageDead(_2);
diff --git a/tests/mir-opt/pre-codegen/slice_iter.slice_iter_next.PreCodegen.after.panic-unwind.mir b/tests/mir-opt/pre-codegen/slice_iter.slice_iter_next.PreCodegen.after.panic-unwind.mir
index 975a8a11fb2..0fe469c21f7 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.slice_iter_next.PreCodegen.after.panic-unwind.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.slice_iter_next.PreCodegen.after.panic-unwind.mir
@@ -8,43 +8,37 @@ fn slice_iter_next(_1: &mut std::slice::Iter<'_, T>) -> Option<&T> {
         let _4: std::ptr::NonNull<T>;
         let mut _7: bool;
         let mut _10: std::ptr::NonNull<T>;
-        let mut _12: bool;
-        let mut _13: *const u8;
-        let mut _14: *const T;
+        let mut _12: usize;
         scope 2 {
             let _3: *const T;
             scope 3 {
-                let _11: *const u8;
+                let _11: usize;
                 scope 4 {
-                    scope 5 (inlined null::<u8>) {
-                        scope 6 (inlined without_provenance::<()>) {
-                            scope 7 (inlined without_provenance_mut::<()>) {
+                    scope 7 (inlined core::num::<impl usize>::unchecked_sub) {
+                        scope 8 (inlined core::ub_checks::check_language_ub) {
+                            scope 9 (inlined core::ub_checks::check_language_ub::runtime) {
                             }
                         }
-                        scope 8 (inlined std::ptr::from_raw_parts::<u8, ()>) {
-                        }
                     }
-                    scope 9 (inlined std::ptr::const_ptr::<impl *const u8>::wrapping_sub) {
-                        scope 10 (inlined core::num::<impl isize>::wrapping_neg) {
-                            scope 11 (inlined core::num::<impl isize>::wrapping_sub) {
-                            }
-                        }
-                        scope 12 (inlined std::ptr::const_ptr::<impl *const u8>::wrapping_offset) {
-                        }
+                    scope 10 (inlined without_provenance_mut::<T>) {
                     }
                 }
-                scope 13 (inlined <NonNull<T> as PartialEq>::eq) {
+                scope 5 (inlined std::ptr::const_ptr::<impl *const T>::addr) {
+                    scope 6 (inlined std::ptr::const_ptr::<impl *const T>::cast::<()>) {
+                    }
+                }
+                scope 11 (inlined <NonNull<T> as PartialEq>::eq) {
                     let mut _5: *mut T;
                     let mut _6: *mut T;
-                    scope 14 (inlined NonNull::<T>::as_ptr) {
+                    scope 12 (inlined NonNull::<T>::as_ptr) {
                     }
-                    scope 15 (inlined NonNull::<T>::as_ptr) {
+                    scope 13 (inlined NonNull::<T>::as_ptr) {
                     }
                 }
-                scope 16 (inlined NonNull::<T>::add) {
+                scope 14 (inlined NonNull::<T>::add) {
                     let mut _8: *const T;
                     let mut _9: *const T;
-                    scope 17 (inlined NonNull::<T>::as_ptr) {
+                    scope 15 (inlined NonNull::<T>::as_ptr) {
                     }
                 }
             }
@@ -55,6 +49,7 @@ fn slice_iter_next(_1: &mut std::slice::Iter<'_, T>) -> Option<&T> {
         StorageLive(_2);
         StorageLive(_3);
         StorageLive(_11);
+        StorageLive(_12);
         StorageLive(_4);
         _2 = copy ((*_1).0: std::ptr::NonNull<T>);
         _3 = copy ((*_1).1: *const T);
@@ -92,42 +87,33 @@ fn slice_iter_next(_1: &mut std::slice::Iter<'_, T>) -> Option<&T> {
     bb3: {
         _0 = const {transmute(0x0000000000000000): Option<&T>};
         StorageDead(_7);
-        goto -> bb9;
+        goto -> bb8;
     }
 
     bb4: {
-        _11 = copy _3 as *const u8 (PtrToPtr);
-        StorageLive(_12);
-        _12 = Eq(copy _11, const {0x0 as *const u8});
-        switchInt(move _12) -> [0: bb5, otherwise: bb8];
+        _11 = copy _3 as usize (Transmute);
+        switchInt(copy _11) -> [0: bb5, otherwise: bb6];
     }
 
     bb5: {
-        StorageDead(_12);
-        StorageLive(_13);
-        _13 = arith_offset::<u8>(move _11, const -1_isize) -> [return: bb6, unwind unreachable];
+        _0 = const {transmute(0x0000000000000000): Option<&T>};
+        goto -> bb8;
     }
 
     bb6: {
-        _14 = move _13 as *const T (PtrToPtr);
-        StorageDead(_13);
-        ((*_1).1: *const T) = copy _14;
+        _12 = SubUnchecked(copy _11, const 1_usize);
+        ((*_1).1: *const T) = copy _12 as *const T (Transmute);
         goto -> bb7;
     }
 
     bb7: {
         _0 = copy _2 as std::option::Option<&T> (Transmute);
-        goto -> bb9;
+        goto -> bb8;
     }
 
     bb8: {
-        _0 = const {transmute(0x0000000000000000): Option<&T>};
-        StorageDead(_12);
-        goto -> bb9;
-    }
-
-    bb9: {
         StorageDead(_4);
+        StorageDead(_12);
         StorageDead(_11);
         StorageDead(_3);
         StorageDead(_2);