| //@ compile-flags: -Copt-level=3 |
| |
| #![crate_type = "lib"] |
| |
| // The bug here was that it was loading and storing the whole value. |
| // It's ok for it to load the discriminant, |
| // to preserve the UB from `unreachable_unchecked`, |
| // but it better only store the constant discriminant of `B`. |
| |
| pub enum State { |
| A([u8; 753]), |
| B([u8; 753]), |
| } |
| |
| // CHECK-LABEL: @update |
| #[no_mangle] |
| pub unsafe fn update(s: *mut State) { |
| // CHECK-NOT: alloca |
| |
| // CHECK-NOT: load |
| // CHECK-NOT: store |
| // CHECK-NOT: memcpy |
| // CHECK-NOT: 75{{3|4}} |
| |
| // CHECK: %[[TAG:.+]] = load i8, ptr %s, align 1 |
| // CHECK-NEXT: trunc nuw i8 %[[TAG]] to i1 |
| |
| // CHECK-NOT: load |
| // CHECK-NOT: store |
| // CHECK-NOT: memcpy |
| // CHECK-NOT: 75{{3|4}} |
| |
| // CHECK: store i8 1, ptr %s, align 1 |
| |
| // CHECK-NOT: load |
| // CHECK-NOT: store |
| // CHECK-NOT: memcpy |
| // CHECK-NOT: 75{{3|4}} |
| |
| // CHECK: ret |
| let State::A(v) = s.read() else { std::hint::unreachable_unchecked() }; |
| s.write(State::B(v)); |
| } |
