should be implemented in ISLE: inst = `v12 = smulhi.i8 v0, v0`, type = `Some(types::I8)`

Reproduction is in Custom MIR. Not sure if this can be triggered from surface rust

#![feature(custom_mir, core_intrinsics)]
extern crate core;
use core::intrinsics::mir::*;

#[custom_mir(dialect = "runtime", phase = "initial")]
pub fn fn13(mut _7: i8) {
    mir! {
    let _25: i16;
    let _31: (i128, i16);
    let _39: i16;
    {
    _31.1 = _7 as i16;
    _25 = _31.1 * _31.1;
    _31 = (50414009528881047150422352225052180952_i128, _25);
    _25 = _31.1 >> _31.0;
    Goto(bb17)
    }
    bb17 = {
    Call(_39 = std::hint::black_box(_25), ReturnTo(bb18), UnwindUnreachable())
    }
    bb18 = {
    Return()
    }

    }
}
pub fn main() {
    fn13(0);
}

$ rustc-clif -Zmir-opt-level=0 -Copt-level=3 929244-debug.rs
thread '<unnamed>' panicked at /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/cranelift-codegen-0.104.0/src/machinst/lower.rs:766:21:
should be implemented in ISLE: inst = `v12 = smulhi.i8 v0, v0`, type = `Some(types::I8)`
stack backtrace:
   0:     0x7ffff978bf86 - std::backtrace_rs::backtrace::libunwind::trace::h514ead2753e1782f
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
   1:     0x7ffff978bf86 - std::backtrace_rs::backtrace::trace_unsynchronized::hbc462e8372651887
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7ffff978bf86 - std::sys_common::backtrace::_print_fmt::he3092ef183bdd613
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7ffff978bf86 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h908f80a389799910
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7ffff97de880 - core::fmt::rt::Argument::fmt::ha9f3d8b02e25296c
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/core/src/fmt/rt.rs:142:9
   5:     0x7ffff97de880 - core::fmt::write::hef880bc86bd63d4b
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/core/src/fmt/mod.rs:1120:17
   6:     0x7ffff977f94f - std::io::Write::write_fmt::h780869503f755b5a
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/std/src/io/mod.rs:1810:15
   7:     0x7ffff978bd64 - std::sys_common::backtrace::_print::h52cc78326ec17ac5
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7ffff978bd64 - std::sys_common::backtrace::print::h44b4c057fd1c7c3f
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7ffff978eaf7 - std::panicking::default_hook::{{closure}}::h99cbf699c09f8685
  10:     0x7ffff978e859 - std::panicking::default_hook::hbc89d54398681576
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/std/src/panicking.rs:292:9
  11:     0x7ffffc54acec - std[1d0ea5b5e602c844]::panicking::update_hook::<alloc[d84df3010862da1b]::boxed::Box<rustc_driver_impl[2078f68ece4ea2b8]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7ffff978f246 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h99950b3f8a1ddee8
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/alloc/src/boxed.rs:2029:9
  13:     0x7ffff978f246 - std::panicking::rust_panic_with_hook::he160495ec53b11e6
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/std/src/panicking.rs:785:13
  14:     0x7ffff978ef92 - std::panicking::begin_panic_handler::{{closure}}::ha86f6320ad4cac49
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/std/src/panicking.rs:659:13
  15:     0x7ffff978c486 - std::sys_common::backtrace::__rust_end_short_backtrace::h19c3911246e5b7ea
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/std/src/sys_common/backtrace.rs:171:18
  16:     0x7ffff978ece4 - rust_begin_unwind
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/std/src/panicking.rs:647:5
  17:     0x7ffff97daf85 - core::panicking::panic_fmt::hd869deda4756f0c1
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/core/src/panicking.rs:72:14
  18:     0x7ffff06f38f8 - cranelift_codegen::machinst::lower::Lower<I>::lower::hf5680db6e8da6825
  19:     0x7ffff05d6739 - cranelift_codegen::machinst::compile::compile::h5311fd7207db3d5c
  20:     0x7ffff06936f5 - <cranelift_codegen::isa::x64::X64Backend as cranelift_codegen::isa::TargetIsa>::compile_function::h590f11e5c6d2c4ff
  21:     0x7ffff0709f5b - cranelift_codegen::context::Context::compile_stencil::h96dc3cd783467e94
  22:     0x7ffff0709c37 - cranelift_codegen::context::Context::compile_and_emit::h593fc7e7957fe7fc
  23:     0x7ffff0499eca - <cranelift_object::backend::ObjectModule as cranelift_module::module::Module>::define_function_with_control_plane::hc9ac75d45c4de148
  24:     0x7ffff03e4ec3 - cranelift_module::module::Module::define_function::hb378a4ac6a6da2a5
  25:     0x7ffff046fd8d - rustc_codegen_cranelift::base::compile_fn::he5118887952ffc76
  26:     0x7ffff042c8ab - std::sys_common::backtrace::__rust_begin_short_backtrace::h37b57af66c3e318c
  27:     0x7ffff0429604 - core::ops::function::FnOnce::call_once{{vtable.shim}}::hb385e8dc4fe3342d
  28:     0x7ffff9798835 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hba0b80fd74ce5417
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/alloc/src/boxed.rs:2015:9
  29:     0x7ffff9798835 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h0ab2d213dcdff51c
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/alloc/src/boxed.rs:2015:9
  30:     0x7ffff9798835 - std::sys::pal::unix::thread::Thread::new::thread_start::h7eeca5a8e186b7ad
                               at /rustc/e7bbe8ce933123a8e327c79e38bcb790595e6a65/library/std/src/sys/pal/unix/thread.rs:108:17
  31:     0x7ffff9586897 - start_thread
  32:     0x7ffff960d564 - __GI___clone
  33:                0x0 - <unknown>

error: the compiler unexpectedly panicked. this is a bug.

note: using internal features is not supported and expected to cause internal compiler errors when used incorrectly

note: please attach the file at `/root/rustlantis-repros/rustc-ice-2024-02-03T11_40_43-99834.txt` to your bug report

note: compiler flags: -C panic=abort -Z panic-abort-tests -Z codegen-backend=/root/rustc_codegen_cranelift/dist/lib/librustc_codegen_cranelift.so -Z mir-opt-level=0 -C opt-level=3

query stack during panic:
end of query stack
warning: 2 warnings emitted

On latest cdae185e3022b6e7c6c7fe363353fe1176a06604

Reproduce the panic with the provided Custom MIR program and rustc-clif command. Start at cranelift-codegen's machinst/lower.rs around line 766, then follow the lowering path from rustc_codegen_cranelift's compile_fn. Done means the reproduction compiles without the unimplemented ISLE panic.