1 files changed, 8 insertions, 0 deletions
diff --git a/compiler/rustc_mir_transform/src/jump_threading.rs b/compiler/rustc_mir_transform/src/jump_threading.rs
index 1844b97887a..9b9b0b705bf 100644
--- a/compiler/rustc_mir_transform/src/jump_threading.rs
+++ b/compiler/rustc_mir_transform/src/jump_threading.rs
@@ -494,8 +494,16 @@ impl<'a, 'tcx> TOFinder<'a, 'tcx> {
             }
             // Transfer the conditions on the copy rhs, after inversing polarity.
             Rvalue::UnaryOp(UnOp::Not, Operand::Move(place) | Operand::Copy(place)) => {
+                if !place.ty(self.body, self.tcx).ty.is_bool() {
+                    // Constructing the conditions by inverting the polarity
+                    // of equality is only correct for bools. That is to say,
+                    // `!a == b` is not `a != b` for integers greater than 1 bit.
+                    return;
+                }
                 let Some(conditions) = state.try_get_idx(lhs, &self.map) else { return };
                 let Some(place) = self.map.find(place.as_ref()) else { return };
+                // FIXME: I think This could be generalized to not bool if we
+                // actually perform a logical not on the condition's value.
                 let conds = conditions.map(self.arena, Condition::inv);
                 state.insert_value_idx(place, conds, &self.map);
             }