[Polonius] Timeout while compiling handcrafted example

[usx95]

(Lower priority: Trying to break compiler after reading polonius algorithm)
I tried this code. N Pointers pointing with N loans. Cyclic swap content of pointers in a for loop. Following is an example for N = 3.

fn main() {
    let s0 = String::from("String 0");
    let s1 = String::from("String 1");
    let s2 = String::from("String 2");

    let mut r0: &String = &s0;
    let mut r1: &String = &s1;
    let mut r2: &String = &s2;

    for _ in 0..1 {
        let t = r0;
        r0 = r1;
        r1 = r2;
        r2 = t;
    }

    println!("r0 points to: {}", r0);
    println!("r1 points to: {}", r1);
    println!("r2 points to: {}", r2);
}

(generator script)
N = 10: https://godbolt.org/z/6Garo4jh9 takes <1s
N = 100: https://godbolt.org/z/Gnrr6rqrr takes about 27s with -Zpolononius, 14s with -Zpolonius=next.
N = 200: https://godbolt.org/z/Gnrr6rqrr takes about 156s with -Zpolononius, 131s with -Zpolonius=next.
N = 1000 takes >20 min

Note that all the above examples compile in <1 s without -Zpolonius. Example: https://godbolt.org/z/GTMGdf1hr

IIUC, the algorithm would converge when all the N region/origin variables would contain (require) all the N loans!
I feel the owners must be aware about this already. The fixed point iteration looks O(R * L) where R is the number of region variables and L is the number of loans/borrow expressions.

Meta

rustc --version --verbose:

rustc 1.88.0-nightly (25cdf1f67 2025-04-28)
binary: rustc
commit-hash: 25cdf1f67463c9365d8d83778c933ec7480e940b
commit-date: 2025-04-28
host: x86_64-unknown-linux-gnu
release: 1.88.0-nightly
LLVM version: 20.1.2