LLVM ERROR: Invalid LLVMRustLinkage value!

[haraldh]

Code

https://github.com/haraldh/rust_llvm_error

❯ cd /tmp
❯ git clone https://github.com/haraldh/rust_llvm_error.git
❯ cd rust_llvm_error/
❯ cargo clean; cargo build
   Compiling scopeguard v1.1.0
   Compiling primordial v0.1.0
   Compiling lock_api v0.4.4
   Compiling spinning v0.1.0
   Compiling llvm_error v0.1.0 (/tmp/rust_llvm_error)
    Finished dev [unoptimized + debuginfo] target(s) in 1.20s

❯ cd ..
❯ mkdir -p /tmp/sfdgfdgdfgfdg/dfghfdgfd/fdfdgfdg/
❯ mv rust_llvm_error /tmp/sfdgfdgdfgfdg/dfghfdgfd/fdfdgfdg/
❯ cd /tmp/sfdgfdgdfgfdg/dfghfdgfd/fdfdgfdg/rust_llvm_error/
❯ cargo clean; cargo build
   Compiling scopeguard v1.1.0
   Compiling primordial v0.1.0
   Compiling lock_api v0.4.4
   Compiling spinning v0.1.0
   Compiling llvm_error v0.1.0 (/tmp/sfdgfdgdfgfdg/dfghfdgfd/fdfdgfdg/rust_llvm_error)
LLVM ERROR: Invalid LLVMRustLinkage value!
error: could not compile `llvm_error`

Meta

rustc --version --verbose:

rustc 1.54.0 (a178d0322 2021-07-26)
binary: rustc
commit-hash: a178d0322ce20e33eac124758e837cbd80a6f633
commit-date: 2021-07-26
host: x86_64-unknown-linux-gnu
release: 1.54.0
LLVM version: 12.0.1

Error output

LLVM ERROR: Invalid LLVMRustLinkage value!
error: could not compile `llvm_error`

[haraldh]

Forgive the unsafe mess :)

[hellow554]

Using a self built rustc, I get this (already c++filtered):

invalid scope
/build/librustc_driver-5f22cd2fd3625224.so(+0x6f0063)[0x7f8914a42063]
/lib/x86_64-linux-gnu/libc.so.6(+0x41030)[0x7f8913fdf030]
/build/libLLVM-12-rust-1.56.0-nightly.so(llvm::SlotTracker::CreateMetadataSlot(llvm::MDNode const*)+0xac)[0x7f8910f2f81c]
/build/libLLVM-12-rust-1.56.0-nightly.so(llvm::SlotTracker::CreateMetadataSlot(llvm::MDNode const*)+0xc5)[0x7f8910f2f835]
/build/libLLVM-12-rust-1.56.0-nightly.so(llvm::SlotTracker::CreateMetadataSlot(llvm::MDNode const*)+0xc5)[0x7f8910f2f835]
/build/libLLVM-12-rust-1.56.0-nightly.so(llvm::SlotTracker::CreateMetadataSlot(llvm::MDNode const*)+0xc5)[0x7f8910f2f835]
/build/libLLVM-12-rust-1.56.0-nightly.so(llvm::SlotTracker::processFunctionMetadata(llvm::Function const&)+0x5d)[0x7f8910f2f8fd]
/build/libLLVM-12-rust-1.56.0-nightly.so(llvm::SlotTracker::processModule()+0x52b)[0x7f8910f2f32b]
/build/libLLVM-12-rust-1.56.0-nightly.so(+0x215cf47)[0x7f8910f47f47]
/build/libLLVM-12-rust-1.56.0-nightly.so(+0x215581e)[0x7f8910f4081e]
/build/libLLVM-12-rust-1.56.0-nightly.so(+0x2312895)[0x7f89110fd895]
/build/libLLVM-12-rust-1.56.0-nightly.so(+0x231278b)[0x7f89110fd78b]
/build/libLLVM-12-rust-1.56.0-nightly.so(+0x230b852)[0x7f89110f6852]
/build/libLLVM-12-rust-1.56.0-nightly.so(+0x230cf0d)[0x7f89110f7f0d]
/build/libLLVM-12-rust-1.56.0-nightly.so(+0x230cf0d)[0x7f89110f7f0d]
/build/libLLVM-12-rust-1.56.0-nightly.so(+0x2308e0c)[0x7f89110f3e0c]
/build/libLLVM-12-rust-1.56.0-nightly.so(+0x23003d5)[0x7f89110eb3d5]
/build/libLLVM-12-rust-1.56.0-nightly.so(+0x2329143)[0x7f8911114143]
/build/libLLVM-12-rust-1.56.0-nightly.so(llvm::FPPassManager::runOnFunction(llvm::Function&)+0x639)[0x7f8911090869]
/build/libLLVM-12-rust-1.56.0-nightly.so(llvm::FPPassManager::runOnModule(llvm::Module&)+0x33)[0x7f8911097703]
/build/libLLVM-12-rust-1.56.0-nightly.so(llvm::legacy::PassManagerImpl::run(llvm::Module&)+0x470)[0x7f89110910d0]
/build/librustc_driver-5f22cd2fd3625224.so(+0x9ddf68)[0x7f8914d2ff68]
/build/librustc_driver-5f22cd2fd3625224.so(+0x9b87a1)[0x7f8914d0a7a1]
/build/librustc_driver-5f22cd2fd3625224.so(+0x9bdf79)[0x7f8914d0ff79]
/build/librustc_driver-5f22cd2fd3625224.so(+0x8870e2)[0x7f8914bd90e2]
/build/librustc_driver-5f22cd2fd3625224.so(+0x880be4)[0x7f8914bd2be4]
/build/librustc_driver-5f22cd2fd3625224.so(+0x97fbbc)[0x7f8914cd1bbc]
/build/librustc_driver-5f22cd2fd3625224.so(+0x982067)[0x7f8914cd4067]
/build/libstd-6bca756cf6c7b5ad.so(rust_metadata_std_4c245a9be68bbd28178e09733609f43+0x7f337)[0x7f891421c337]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x9450)[0x7f890eb9d450]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x43)[0x7f89140b5e73]
error: could not compile `llvm_error`

I also got this recently:

munmap_chunk(): invalid pointer
warning: `llvm_error` (bin "llvm_error") generated 4 warnings
error: could not compile `llvm_error`; 4 warnings emitted

Caused by:
  process didn't exit successfully: `/home/marcel/projects/rust/llvm-path/build/x86_64-unknown-linux-gnu/stage1/bin/rustc --crate-name llvm_error --edition=2018 src/main.rs --error-format=json --json=diagnostic-rendered-ansi --crate-type bin --emit=dep-info,link -C embed-bitcode=no -C debuginfo=2 -C metadata=5e69652675a71d2c -C extra-filename=-5e69652675a71d2c --out-dir /tmp/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/target/debug/deps -C incremental=/tmp/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/target/debug/incremental -L dependency=/tmp/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/asdf/target/debug/deps` (signal: 6, SIGABRT: process abort signal)

[hellow554]

I managed to recude the code a lot.
The problem is, that the error happens on random.

I'm not sure why or what, but when running it ten times (cargo clean; cargo build) it happens maybe once...

#![feature(once_cell)]

pub mod addr {
    use std::convert::TryFrom;
    use std::marker::PhantomData as PD;

    extern "C" {
        pub static _ENARX_SALLYPORT_START: u8;
    }

    pub struct Address<T, U>(T, PD<U>);
    impl<T, U> Address<T, U> {
        pub fn f<Z>(_: &Z) -> Self {
            todo!()
        }
    }

    pub struct ShimVirtAddr<U>(Address<u64, U>);
    impl<U> TryFrom<Address<u64, U>> for ShimVirtAddr<U> {
        type Error = ();
        fn try_from(_: Address<u64, U>) -> Result<Self, Self::Error> {
            Err(())
        }
    }

    pub struct ShimPhysUnencryptedAddr<U>(Address<u64, U>);

    impl<U> ShimPhysUnencryptedAddr<U> {
        pub fn into_mut<'a>(self) -> &'a mut U {
            unsafe { &mut *(self.0 .0 as *mut U) }
        }
    }

    impl<U> TryFrom<ShimVirtAddr<U>> for ShimPhysUnencryptedAddr<U> {
        type Error = ();

        #[inline(always)]
        fn try_from(_: ShimVirtAddr<U>) -> Result<Self, Self::Error> {
            let _a = 0 < unsafe { &_ENARX_SALLYPORT_START as *const _ as u64 };

            Err(())
        }
    }
}
pub mod hostcall {
    extern "C" {
        pub static _ENARX_SALLYPORT_START: Block;
    }
    use std::convert::TryFrom;
    use std::lazy::SyncLazy;

    use crate::addr::{Address, ShimPhysUnencryptedAddr, ShimVirtAddr};

    #[repr(C)]
    #[derive(Copy, Clone)]
    pub struct Block {
        buf: [u8; 100],
    }

    pub static HOST_CALL_ALLOC: SyncLazy<HostCallAllocator> = SyncLazy::new(|| {
        let _a: *mut Block = unsafe {
            let address = Address::<u64, Block>::f(&_ENARX_SALLYPORT_START);
            let shim_virt = ShimVirtAddr::<Block>::try_from(address).unwrap();

            ShimPhysUnencryptedAddr::<Block>::try_from(shim_virt)
                .unwrap()
                .into_mut() as *mut _
        };
        HostCallAllocator([None, None])
    });

    pub struct HostCallAllocator([Option<&'static mut Block>; 2]);
}

fn main() {}

@jonas-schievink would you mind pinging the LLVM crew? I don't know what to do here :(

[hellow554]

With a custom built llvm (and asserts on) I will now get this error every time 🎉

rustc: /home/marcel/projects/rust/llvm-path/src/llvm-project/llvm/include/llvm/Support/Casting.h:269: typename llvm::cast_retty<X, Y*>::ret_type llvm::cast(Y*) [with X = llvm::GlobalValue; Y = llvm::Value; typename llvm::cast_retty<X, Y*>::ret_type = llvm::GlobalValue*]: Assertion `isa<X>(Val) && "cast<Ty>() argument of incompatible type!"' failed.

[jonas-schievink]

@rustbot ping llvm

[rustbot]

Hey LLVM ICE-breakers! This bug has been identified as a good
"LLVM ICE-breaking candidate". In case it's useful, here are some
instructions for tackling these sorts of bugs. Maybe take a look?
Thanks! <3

cc @camelid @comex @cuviper @DutchGhost @hdhoang @henryboisdequin @heyrutvik @higuoxing @JOE1994 @jryans @mmilenko @nagisa @nikic @Noah-Kennedy @SiavoshZarrasvand @spastorino @vertexclique

[hellow554]

So, I got this:

#[inline(always)]
fn other_ext() {
    extern "C" {
        pub static _ENARX_SALLYPORT_START: u8;
    }
    unsafe { drop(&_ENARX_SALLYPORT_START) };
}

#[inline(always)]
fn this_ext() {
    extern "C" {
        pub static _ENARX_SALLYPORT_START: u16;
    }
    unsafe { drop(&_ENARX_SALLYPORT_START) };
}

fn main() {
    this_ext();
    other_ext();
}

The key is to have two identical named extern variables with a different type. They have be called and inlined for this to work.

I'm not sure if bisecting here is helpful because it will probably bisect to the LLVM12 merge. But the LLVM people here on the repo should be able to find something :)

Have fun

[haraldh]

Still spurious.

❯ i=1; cargo clean; while ! grep -q 'LLVM ERROR' <(cargo build 2>&1 | tee log); do cargo clean; echo "Pass $i"; ((i++)); done; cat log
Pass 1
   Compiling llvm_erro v0.1.0 (/tmp/sfdgfdgdfgfdg/dfghfdgfd/fdfdgfdg/llvm_erro)
LLVM ERROR: Invalid LLVMRustVisibility value!

❯ i=1; cargo clean; while ! grep -q 'LLVM ERROR' <(cargo build 2>&1 | tee log); do cargo clean; echo "Pass $i"; ((i++)); done; cat log
Pass 1
Pass 2
Pass 3
Pass 4
Pass 5
Pass 6
Pass 7
   Compiling llvm_erro v0.1.0 (/tmp/sfdgfdgdfgfdg/dfghfdgfd/fdfdgfdg/llvm_erro)
LLVM ERROR: Invalid LLVMRustVisibility value!

❯ i=1; cargo clean; while ! grep -q 'LLVM ERROR' <(cargo build 2>&1 | tee log); do cargo clean; echo "Pass $i"; ((i++)); done; cat log
Pass 1
Pass 2
Pass 3
Pass 4
Pass 5
Pass 6
   Compiling llvm_erro v0.1.0 (/tmp/sfdgfdgdfgfdg/dfghfdgfd/fdfdgfdg/llvm_erro)
LLVM ERROR: Invalid LLVMRustVisibility value!

❯ i=1; cargo clean; while ! grep -q 'LLVM ERROR' <(cargo build 2>&1 | tee log); do cargo clean; echo "Pass $i"; ((i++)); done; cat log
Pass 1
   Compiling llvm_erro v0.1.0 (/tmp/sfdgfdgdfgfdg/dfghfdgfd/fdfdgfdg/llvm_erro)
LLVM ERROR: Invalid LLVMRustVisibility value!

[hellow554]

Still spurious.

Yes and no.

Quote:

With a custom built llvm (and asserts on) I will now get this error every time 🎉

So the key here is to have a LLVM backend with asserts enabled. AFAIK this is only possible to have when you build LLVM on your own (using x.py) and not with a pre-built build artifact.
There are the -alt builds which have asserts enabled and they give me the same result as my local built rustc (which is unsurprising and expected ;) )
You can use https://github.com/kennytm/rustup-toolchain-install-master to install them.

[apiraino]

Assigning priority based on the discussion for #87933 in the Zulip thread of the Prioritization Working Group.

@rustbot label +regression-from-stable-to-stable +P-high