Miscompile at -Copt-level=1

I think this is an LLVM SROA bug, it reproduces with -Cno-prepopulate-passes -Cpasses=sroa.

I'm running out of ideas for how to minimize this. Maybe it's minimal?

#![feature(custom_mir, core_intrinsics)]
extern crate core;
use core::intrinsics::mir::*;
#[inline(never)]
fn opaque<T>(t: T) {std::hint::black_box(t);}
#[inline(never)]
#[custom_mir(dialect = "runtime", phase = "initial")]
pub fn fn0() -> ([u8; 1], u32) {
    mir! {
        let _1: (([u8; 1], u32), [u8; 5]);
        let _2: ();
        {
            _1.0.0 = [0];
            _1.0.1 = 2;
            _1.1 = [0, 0, 0, 0, 0];
            Call(RET = fn1(_1.0, _1.0, _1), ReturnTo(bb2), UnwindUnreachable())
        }
        bb2 = {
            Call(_2 = opaque(Move(_1)), ReturnTo(bb3), UnwindUnreachable())
        }
        bb3 = {
            Return()
        }
    }
}
#[inline(never)]
#[custom_mir(dialect = "runtime", phase = "initial")]
fn fn1(
    mut _1: ([u8; 1], u32),
    mut _2: ([u8; 1], u32),
    mut _3: (([u8; 1], u32), [u8; 5]),
) -> ([u8; 1], u32) {
    mir! {
        let _4: ();
        {
            _1 = (_3.0.0, 0);
            _3.0 = _1;
            RET = _1;
            Call(_4 = opaque(_2.1), ReturnTo(bb6), UnwindUnreachable())
        }
        bb6 = {
            Call(_4 = opaque(Move(_3)), ReturnTo(bb7), UnwindUnreachable())
        }
        bb7 = {
            Return()
        }
    }
}

fn main() {
    println!("{:?}", fn0());
}

Miri prints:

([0], 0)

rustc -Copt-level=1 -Zmir-opt-level=0 prints:

([0], 2)