LLVM ERROR: Module has aliases, which NVPTX does not support.

[ahendriksen]

Hi,

Thanks for creating this great package! I have tried to get rust-ptx-builder to work, but I have not yet succeeded. I get the error 'LLVM ERROR: Module has aliases, which NVPTX does not support.'. To make sure that I was not an error on my part, I have tried to build one of the example projects in rust-ptx-support.

This is what I get:

$ cargo build
   Compiling cuda-println v0.1.0 (/export/scratch1/hendriks/projects/rustacuda_example/rust-ptx-support/examples/cuda-println)
error: failed to run custom build command for `cuda-println v0.1.0 (/export/scratch1/hendriks/projects/rustacuda_example/rust-ptx-support/examples/cuda-println)`
process didn't exit successfully: `/export/scratch1/hendriks/projects/rustacuda_example/rust-ptx-support/target/debug/build/cuda-println-0022aa50cae5c930/build-script-build` (exit code: 1)
--- stderr
[PTX] Unable to build a PTX crate!
[PTX]    Compiling cuda-println v0.1.0 (/export/scratch1/hendriks/projects/rustacuda_example/rust-ptx-support/examples/cuda-println)
[PTX] error: linking with `ptx-linker` failed: exit code: 1
[PTX]   |
[PTX]   = note: "ptx-linker" "-L" "/ufs/hendriks/.xargo/lib/rustlib/nvptx64-nvidia-cuda/lib" "/tmp/ptx-builder-0.5/cuda_println/d623bafb1eb4deca/nvptx64-nvidia-cuda/release/deps/cuda_println-01803fec47121bc1.cuda_println.2jagi3my-cgu.0.rcgu.o" "/tmp/ptx-builder-0.5/cuda_println/d623bafb1eb4deca/nvptx64-nvidia-cuda/release/deps/cuda_println-01803fec47121bc1.cuda_println.2jagi3my-cgu.1.rcgu.o" "-o" "/tmp/ptx-builder-0.5/cuda_println/d623bafb1eb4deca/nvptx64-nvidia-cuda/release/deps/cuda_println-01803fec47121bc1.ptx" "/tmp/ptx-builder-0.5/cuda_println/d623bafb1eb4deca/nvptx64-nvidia-cuda/release/deps/cuda_println-01803fec47121bc1.1w5kxn6gnyc7w18l.rcgu.o" "-O1" "-L" "/tmp/ptx-builder-0.5/cuda_println/d623bafb1eb4deca/nvptx64-nvidia-cuda/release/deps" "-L" "/tmp/ptx-builder-0.5/cuda_println/d623bafb1eb4deca/release/deps" "-L" "/ufs/hendriks/.xargo/lib/rustlib/nvptx64-nvidia-cuda/lib" "--start-group" "-Bstatic" "--whole-archive" "/tmp/rustchm5YG8/libptx_support-bac6370d784080de.rlib" "--no-whole-archive" "--whole-archive" "/tmp/rustchm5YG8/libcore-5040dc495f9f5fc0.rlib" "--no-whole-archive" "--end-group" "/tmp/rustchm5YG8/libcompiler_builtins-44064ef211638321.rlib" "-shared" "-Bdynamic"
[PTX]   = note:  [INFO] Going to link 3 bitcode modules and 3 rlibs...
[PTX]                   
[PTX]            [INFO] Linking with Link Time Optimisation
[PTX]           LLVM ERROR: Module has aliases, which NVPTX does not support.
[PTX]           
[PTX] 
[PTX] error: aborting due to previous error
[PTX] 
[PTX] error: Could not compile `cuda-println`.
[PTX] 

Unfortunately, I cannot seem to get more verbose output than this. I have installed xargo and ptx-linker. I have CUDA_LIBRARY_PATH set correctly. I do not have LLVM installed locally.

I tried with the following versions of rustc:

• rustc 1.32.0-nightly (14997d56a 2018-12-05) failed: same reason
• rustc 1.32.0-nightly (b3af09205 2018-12-04) failed: same reason
• rustc 1.32.0-nightly (5aff30734 2018-11-19) failed: different reason - "note: Unable to find LLVM shared lib in possible locations:"
• rustc 1.32.0-nightly (653da4fd0 2018-11-08) failed: different reason - "note: Unable to find LLVM shared lib in possible locations:"
• rustc 1.32.0-nightly (36a50c29f 2018-11-09) failed: different reason - "note: Unable to find LLVM shared lib in possible locations:"
• rustc 1.31.0-nightly (de9666f12 2018-10-31) failed: different reason - "note: Unable to find LLVM shared lib in possible locations:"

I am not sure which of these errors occurs earlier in the compilation process, the module alias error, or the LLVM shared lib error.

If there is anything I can do to make this issue more specific, please let me know!

[Frequenzmodulation]

Hi,

I'm getting the same error, even for a minimal example like

#![feature(core_intrinsics)]

#![no_std]
fn foo() {}

#[panic_handler]
unsafe fn breakpoint_panic_handler(_: &::core::panic::PanicInfo) -> ! {
    core::intrinsics::breakpoint();
    core::hint::unreachable_unchecked();
}

When I do RUST_TARGET_PATH=$(pwd) xargo rustc --target nvptx64-nvidia-cuda -- --emit=asm I don't get errors, it just hangs.

I ran out of ideas what to try for now, so any suggestions what to do next are greatly appreciated. Thanks!

[denzp]

Sorry for a late response. The problem was reported in rust-lang/rust#57356 and you can track its progress in rust-lang/rust#57268. As soon as the PR will be merged, there will be a chance to disable an optimisation pass that causes the issue.

[denzp]

Could you please try the updated ptx-linker? Version 0.8.3 contains a modified target specification json with the disabled optimisation pass.

rm -rf /tmp/ptx-builder-targets-0.5
cargo install -f ptx-linker
ptx-linker -V

[Frequenzmodulation]

Thank you for this suggestion.
After following your steps and cargo clean I get

$ ptx-linker -V
ptx-linker 0.8.3
$ cargo build
...
[PTX]            [INFO] Linking without optimisations
[PTX]           LLVM ERROR: Module has aliases, which NVPTX does not support.
...
[PTX] error: aborting due to previous error

Are the troubling optimisations done before linking time?

[denzp]

Sorry, forgot to mention: it also has to be a recent Rust nightly (7bac68a5d 2019-01-21 works for me).

[Frequenzmodulation]

This looks like progress. Still not quite.

$ rustup install nightly-2019-01-21
...
$ rustup default nightly-2019-01-21
...
$ cargo build
...
error: unrecognized platform-specific intrinsic function: `nvptx_block_dim_x`
 --> ${HOME}/.cargo/registry/src/github.com-1ecc6299db9ec823/nvptx-builtins-0.1.0/src/intrinsics.rs:5:5
  |
5 |     pub fn nvptx_block_dim_x() -> i32;
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: unrecognized platform-specific intrinsic function: `nvptx_block_dim_y`
 --> ${HOME}/.cargo/registry/src/github.com-1ecc6299db9ec823/nvptx-builtins-0.1.0/src/intrinsics.rs:8:5
  |
8 |     pub fn nvptx_block_dim_y() -> i32;
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: unrecognized platform-specific intrinsic function: `nvptx_block_dim_z`
  --> ${HOME}/.cargo/registry/src/github.com-1ecc6299db9ec823/nvptx-builtins-0.1.0/src/intrinsics.rs:11:5
   |
11 |     pub fn nvptx_block_dim_z() -> i32;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: unrecognized platform-specific intrinsic function: `nvptx_block_idx_x`
  --> ${HOME}/.cargo/registry/src/github.com-1ecc6299db9ec823/nvptx-builtins-0.1.0/src/intrinsics.rs:14:5
   |
14 |     pub fn nvptx_block_idx_x() -> i32;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: unrecognized platform-specific intrinsic function: `nvptx_block_idx_y`
  --> ${HOME}/.cargo/registry/src/github.com-1ecc6299db9ec823/nvptx-builtins-0.1.0/src/intrinsics.rs:17:5
   |
17 |     pub fn nvptx_block_idx_y() -> i32;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: unrecognized platform-specific intrinsic function: `nvptx_block_idx_z`
  --> ${HOME}/.cargo/registry/src/github.com-1ecc6299db9ec823/nvptx-builtins-0.1.0/src/intrinsics.rs:20:5
   |
20 |     pub fn nvptx_block_idx_z() -> i32;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: unrecognized platform-specific intrinsic function: `nvptx_grid_dim_x`
  --> ${HOME}/.cargo/registry/src/github.com-1ecc6299db9ec823/nvptx-builtins-0.1.0/src/intrinsics.rs:23:5
   |
23 |     pub fn nvptx_grid_dim_x() -> i32;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: unrecognized platform-specific intrinsic function: `nvptx_grid_dim_y`
  --> ${HOME}/.cargo/registry/src/github.com-1ecc6299db9ec823/nvptx-builtins-0.1.0/src/intrinsics.rs:26:5
   |
26 |     pub fn nvptx_grid_dim_y() -> i32;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: unrecognized platform-specific intrinsic function: `nvptx_grid_dim_z`
  --> ${HOME}/.cargo/registry/src/github.com-1ecc6299db9ec823/nvptx-builtins-0.1.0/src/intrinsics.rs:29:5
   |
29 |     pub fn nvptx_grid_dim_z() -> i32;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: unrecognized platform-specific intrinsic function: `nvptx_syncthreads`
  --> ${HOME}/.cargo/registry/src/github.com-1ecc6299db9ec823/nvptx-builtins-0.1.0/src/intrinsics.rs:32:5
   |
32 |     pub fn nvptx_syncthreads() -> ();
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: unrecognized platform-specific intrinsic function: `nvptx_thread_idx_x`
  --> ${HOME}/.cargo/registry/src/github.com-1ecc6299db9ec823/nvptx-builtins-0.1.0/src/intrinsics.rs:35:5
   |
35 |     pub fn nvptx_thread_idx_x() -> i32;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: unrecognized platform-specific intrinsic function: `nvptx_thread_idx_y`
  --> ${HOME}/.cargo/registry/src/github.com-1ecc6299db9ec823/nvptx-builtins-0.1.0/src/intrinsics.rs:38:5
   |
38 |     pub fn nvptx_thread_idx_y() -> i32;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: unrecognized platform-specific intrinsic function: `nvptx_thread_idx_z`
  --> ${HOME}/.cargo/registry/src/github.com-1ecc6299db9ec823/nvptx-builtins-0.1.0/src/intrinsics.rs:41:5
   |
41 |     pub fn nvptx_thread_idx_z() -> i32;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 13 previous errors

error: Could not compile `nvptx-builtins`.

[denzp]

Yes, unfortunately, nvptx-builtins is deprecated.

I applied the following trivial fix to a test crate at ptx-linker:
denzp/rust-ptx-linker@92f8f0f#diff-7a043822a4ef5ff6e6e78275cb97f70f

Functions in core::arch::nvptx are similar to those exported from nvptx-builtins, just prefixed with underscore.

[Frequenzmodulation]

I'm trying to compile your ptx-linker intrinsics example.
First I got:

error: linker `legacy-ptx-linker` not found
  |
  = note: No such file or directory (os error 2)

After this hack: export PATH=$PATH:../../target/release/ I get:

$ xargo build --target nvptx64-nvidia-cuda --release
   Compiling example v0.1.0 (${HOME}/rust-ptx-linker/examples/intrinsics)
error: linking with `legacy-ptx-linker` failed: signal: 4
  |
  = note: "legacy-ptx-linker" "-L" "${HOME}/.xargo/lib/rustlib/nvptx64-nvidia-cuda/lib" "${HOME}/rust-ptx-linker/examples/intrinsics/target/nvptx64-nvidia-cuda/release/deps/example.example.9zaa1d02-cgu.0.rcgu.o" "${HOME}/rust-ptx-linker/examples/intrinsics/target/nvptx64-nvidia-cuda/release/deps/example.example.9zaa1d02-cgu.1.rcgu.o" "-o" "${HOME}/rust-ptx-linker/examples/intrinsics/target/nvptx64-nvidia-cuda/release/deps/example.ptx" "${HOME}/rust-ptx-linker/examples/intrinsics/target/nvptx64-nvidia-cuda/release/deps/example.57v44vf34hrady31.rcgu.o" "-O1" "-L" "${HOME}/rust-ptx-linker/examples/intrinsics/target/nvptx64-nvidia-cuda/release/deps" "-L" "${HOME}/rust-ptx-linker/examples/intrinsics/target/release/deps" "-L" "${HOME}/.xargo/lib/rustlib/nvptx64-nvidia-cuda/lib" "-Bstatic" "--whole-archive" "/tmp/rustc3Vk5Cr/librustc_std_workspace_core-7aab447a2eaf1c96.rlib" "--no-whole-archive" "--whole-archive" "/tmp/rustc3Vk5Cr/libcore-5f9f04db0e313fa5.rlib" "--no-whole-archive" "/tmp/rustc3Vk5Cr/libcompiler_builtins-7defd96cc8eb2126.rlib" "-shared" "-Bdynamic"
  = note: Unable to find LLVM shared lib in possible locations:
          - ${HOME}/.xargo/lib/rustlib/x86_64-unknown-linux-gnu/codegen-backends
          - ${HOME}/.cargo/codegen-backends
          - ${HOME}/.cargo/codegen-backends
          - ${HOME}/.cabal/codegen-backends
          - ${HOME}/.cargo/codegen-backends
          - ${HOME}/codegen-backends
          - ${HOME}/.cabal/codegen-backends
          - /usr/local/codegen-backends
          - /usr/local/codegen-backends
          - /usr/codegen-backends
          - /usr/codegen-backends
          - /codegen-backends
          - /codegen-backends
          - /usr/codegen-backends
          - /usr/local/codegen-backends
          - /snap/codegen-backends
          - ${HOME}/codegen-backends
          - ${HOME}/.local/codegen-backends
          - /usr/local/cuda-8.0/codegen-backends
          - ${HOME}/codegen-backends
          - ${HOME}/.local/codegen-backends
          - /usr/local/cuda-8.0/codegen-backends
          - ../../target/codegen-backends
          - ${HOME}/.rustup/toolchains/nightly-2019-01-21-x86_64-unknown-linux-gnu/lib/rustlib/2019-01-21-x86_64-unknown-linux-gnu/codegen-backends
          - ${HOME}/.rustup/toolchains/nightly-2019-01-21-x86_64-unknown-linux-gnu/lib/rustlib/2019-01-21-x86_64-unknown-linux-gnu/codegen-backends
          - ${HOME}/rust-ptx-linker/examples/intrinsics/target/release/lib/rustlib/codegen-backends
          - ${HOME}/.rustup/toolchains/nightly-2019-01-21-x86_64-unknown-linux-gnu/lib/rustlib/2019-01-21-x86_64-unknown-linux-gnu/codegen-backends
          - ${HOME}/.rustup/toolchains/nightly-2019-01-21-x86_64-unknown-linux-gnu/lib/rustlib/2019-01-21-x86_64-unknown-linux-gnu/codegen-backends
          - ${HOME}/.rustup/toolchains/nightly-2019-01-21-x86_64-unknown-linux-gnu/lib/rustlib/2019-01-21-x86_64-unknown-linux-gnu/codegen-backends
          - ${HOME}/.rustup/toolchains/nightly-2019-01-21-x86_64-unknown-linux-gnu/lib/rustlib/2019-01-21-x86_64-unknown-linux-gnu/codegen-backends
          thread 'main' panicked at 'explicit panic', ${HOME}/.cargo/registry/src/github.com-1ecc6299db9ec823/rustc-llvm-proxy-0.1.7/src/lib.rs:58:17
          note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
          

error: aborting due to previous error

error: Could not compile `example`.

I'm somewhat new to Rust, thanks for all your help!

[denzp]

That's a nice catch, thanks. I can reproduce your problem!
Seems like, the linker cannot find the LLVM library when using a specific Rust version (nightly-2019-01-21 instead of nightly).

I'll post here when the issue will be fixed.

[denzp]

@Frequenzmodulation can you please pull the latest ptx-linker and try to compile the example again?

I've added a code to handle the case: denzp/rustc-llvm-proxy@20815b5

[Frequenzmodulation]

@denzp Thank you, seems it did the trick! I produces target/nvptx64-nvidia-cuda/release/example.ptx.

[ahendriksen]

Great! that fixes my issue :)

Sorry for the long delay!