LLVM miscompilation in instcombine

#![feature(custom_mir, core_intrinsics)]
extern crate core;
use core::intrinsics::mir::*;
fn main() {
    println!("{}", oof());
}
#[custom_mir(dialect = "runtime", phase = "initial")]
fn oof() -> isize {
    mir! {
        let _2: isize;
        let _3: f64;
        let _4: isize;
        let _6: isize;
        let _7: isize;
        let _9: isize;
        let _10: isize;
        let _8: isize;
        let _13: char;
        let _14: i8;
        let _16: &'static mut char;
        let _21: u64;
        let _25: *const i8;
        let _32: &'static mut char;
        let _35: isize;
        let _68: isize;
        {
            _7 = isize::MIN;
            _9 = isize::MIN;
            _10 = isize::MIN;
            _8 = 0;
            _2 = isize::MAX;
            Goto(bb2)
        }
        bb2 = {
            _4 = _7 & _8;
            _6 = !_4;
            _8 = _2 >> _6;
            _4 = _9 & _7;
            _7 = !_8;
            _16 = &mut _13;
            Goto(bb4)
        }
        bb4 = {
            _6 = _7 | _10;
            _8 = _6 << _7;
            _3 = _8 as f64;
            _25 = core::ptr::addr_of!(_14);
            _9 = 0;
            _10 = !_4;
            _35 = _3 as isize;
            _32 = _16;
            _21 = 1;
            match _21 {
                0_u64 => bb4,
                _ => bb29,
            }
        }
        bb29 = {
            _7 = _10 & _6;
            _2 = _6;
            *_25 = 1;
            match *_25 {
                1 => bb39,
                _ => bb2
            }
        }
        bb39 = {
            _68 = _7 & _35;
            Call(*_32 = fn17(_25), ReturnTo(bb56), UnwindUnreachable())
        }
        bb56 = {
            RET = _68;
            Return()
        }
    }
}
fn fn17(_: *const i8) -> char {
    'a'
}

Compile with

rustc +nightly -Zmir-opt-level=0 -Copt-level=1 -o $OUT -Cno-prepopulate-passes -Cpasses=sroa,instcombine

And the executable will print

-9223372036854775808

But if run with Miri:

MIRIFLAGS="-Zmiri-tree-borrows -Zmiri-no-short-fd-operations" cargo +nightly miri run

It will print 0.