Convert from `rustc_smir` to `stable_mir` fail

[zhuyutian57]

I try to get stable MIR for a project built by cargo. As the project is large(8k+ lines codes), I try to get the body of each function. But it fails to covert datas from Table.

The code called mir_body:

    for item in stable_mir::all_local_items() {
      if item.kind() == ItemKind::Fn {
        println!("{item:?}");
        if item.trimmed_name() == "Convert::convert_address_of" {
          println!("{:?}", item.body());
        }
      }
    }

The output:

...
CrateItem(DefId { id: 449, name: "solvers::smt::smt_conv::Convert::convert_symbol" })
CrateItem(DefId { id: 450, name: "solvers::smt::smt_conv::Convert::convert_address_of" })

thread 'rustc' panicked at compiler/rustc_smir/src/rustc_smir/alloc.rs:30:10:
Failed to convert: Scalar(0x0000000000000000) to std::option::Option<&'{erased} Ast/#2>: Error("TooGeneric(Alias(Projection, AliasTy { args: [Ast/#2], def_id: DefId(2:2374 ~ core[9e5e]::ptr::metadata::Pointee::Metadata), .. }))")
stack backtrace:
   0: rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::result::unwrap_failed
   3: rustc_smir::rustc_smir::alloc::new_allocation
   4: <rustc_middle::mir::consts::Const as rustc_smir::rustc_smir::Stable>::stable
   5: <rustc_middle::mir::syntax::Operand as rustc_smir::rustc_smir::Stable>::stable
   6: <rustc_middle::mir::syntax::TerminatorKind as rustc_smir::rustc_smir::Stable>::stable
   7: <rustc_middle::mir::terminator::Terminator as rustc_smir::rustc_smir::Stable>::stable
   8: <rustc_middle::mir::Body as rustc_smir::rustc_smir::Stable>::stable
   9: <rustc_smir::rustc_smir::context::TablesWrapper as stable_mir::compiler_interface::Context>::mir_body
  10: <stable_mir::CrateItem>::body
  11: mirv::config::config::Config::new
  12: <mirv::main::StableMir<B,C,F> as rustc_driver_impl::Callbacks>::after_analysis
  13: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  14: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}

Then, I follow the code of rustc_smir. I found that the definition of Table is

pub struct Tables<'tcx> {
    ...,
    pub(crate) def_ids: IndexMap<DefId, stable_mir::DefId>,
  ...
}

However, the function of mir_body is

fn mir_body(&self, item: stable_mir::DefId) -> stable_mir::mir::Body {
        let mut tables = self.0.borrow_mut();
        let def_id = tables[item];
        tables.tcx.instance_mir(rustc_middle::ty::InstanceKind::Item(def_id)).stable(&mut tables)
    }

table[item] will enventually call self.def_ids[item]. Then, the index of table[item] is stable_mir::DefId while the key of def_ids has type DefId. Is there a bug?

[celinval]

Hi @zhuyutian57, is the crate your compiling open source? Or are you able to create a small reproducible example?

It looks like the issue is related to our handling of constants.

[zhuyutian57]

Hi @zhuyutian57, is the crate your compiling open source? Or are you able to create a small reproducible example?

It looks like the issue is related to our handling of constants.

I make my repo public. You can follow the instructions by using cargo-mirv on the repo. When the function convert_address_of is accessed, the above error occurs.

[makai410]

the problem seems to surround here:

// solvers/smt/smt_conv.rs#242
fn convert_pointer(&self, base: &Ast, offset: &Ast, meta: Option<&Ast>) -> Ast;

while convert_address_of would do this:

// solvers/smt/smt_conv.rs#296
return self.convert_pointer(&base, &offset, None);

This corresponds to the error message.
Could you create a minimal reproducible example?

[zhuyutian57]

It is not easy to minimize the example. I tried to delete unrelated code, but it works.

[makai410]

Thanks for catching this. I will try to take a look at it next week.

[celinval]

Hi @makai410, were you able to reproduce this issue?

[makai410]

Unfortunately, not yet. I will look into it this week.

[celinval]

No worries... Just checking in.

[makai410]

Okay finally here is a minimal reproducible example:

use std::fmt::Debug;

pub trait Meow<A: Clone + Debug> {
    fn foo(&self, a: Option<&A>) -> A;

    fn fzz(&self) -> A {
        self.foo(None)
    }
}

fn main() {
    
}

[makai410]

Ummmm kinda weird...

I reproduced this issue using mirv, and it appears to be triggered by -Copt-level=1, since removing this argument resolves the problem.
See mirv::cli for more details.

However, I failed to reproduce it after adding an ui test to ui-fulldeps/stable-mir:

//@ run-pass

//@ ignore-stage1
//@ ignore-cross-compile
//@ ignore-remote
//@ edition: 2021

#![feature(rustc_private)]
#![feature(assert_matches)]

extern crate rustc_middle;
#[macro_use]
extern crate rustc_smir;
extern crate rustc_driver;
extern crate rustc_interface;
extern crate stable_mir;

use std::io::Write;
use std::ops::ControlFlow;

const CRATE_NAME: &str = "ice";

/// This function uses the Stable MIR APIs to get information about the test crate.
fn check_ice() -> ControlFlow<()> {
    for item in stable_mir::all_local_items() {
        println!("{item:?}");
    }

    ControlFlow::Continue(())
}

fn main() {
    let path = "ice-alloc.rs";
    generate_input(&path).unwrap();
    let args = &[
        "rustc".to_string(),
        "-Copt-level=1".to_string(),
        "--crate-type=lib".to_string(),
        "--crate-name".to_string(),
        CRATE_NAME.to_string(),
        path.to_string(),
    ];
    run!(args, check_ice).unwrap();
}

fn generate_input(path: &str) -> std::io::Result<()> {
    let mut file = std::fs::File::create(path)?;
    write!(
        file,
        r#"
        #![allow(dead_code, unused_variables)]
        use std::fmt::Debug;

        pub trait Meow<A: Clone + Debug> {{
            fn foo(&self, a: Option<&A>) -> A;

            fn fzz(&self) -> A {{
                self.foo(None)
            }}
        }}

        fn main() {{
        }}
    "#
    )?;
    Ok(())
}

🤔 No clues yet. Any ideas?

[makai410]

Ahh, this version can reproduce this issue:

/// This function uses the Stable MIR APIs to get information about the test crate.
fn check_ice() -> ControlFlow<()> {
    let local = stable_mir::local_crate();
    for def in local.fn_defs() {
        let _ = def.body();
    }

    ControlFlow::Continue(())
}