// in Rust 1.73, -O and opt-level=3 optimizes differently
//@ compile-flags: -C opt-level=3
//@ min-llvm-version: 17
#![crate_type = "lib"]

use std::cmp::max;

#[no_mangle]
// CHECK-LABEL: @foo
// CHECK-NOT: slice_start_index_len_fail
// CHECK-NOT: unreachable
pub fn foo(v: &mut Vec<u8>, size: usize)-> Option<&mut [u8]> {
    if v.len() > max(1, size) {
        let start = v.len() - size;
        Some(&mut v[start..])
    } else {
        None
    }
}