chore(example): add nvvm library path to LD_LIBRARY_PATH and add back the add example in CI (#190)

When linking `libnvvm.so.4` into `librustc_codegen_nvvm.so` shared
library via the `cust_raw` package, we specified the following
parameters in the `build.rs`:

- cargo::rustc-link-search=native=xxx
- cargo::rustc-link-lib=dylib=nvvm

According to the [Cargo documentation](https://doc.rust-lang.org/cargo/reference/build-scripts.html#rustc-link-search),
the path we added to the `rustc-link-search` parameter is not further
populated to the `LD_LIBRARY_PATH` for search by the transitive
dependencies.

> These paths are also added to the dynamic library search path
> environment variable if they are within the OUT_DIR.

The behavior is intended to be limited to the OUT_DIR so the
`libnvvm.so.4`, which lives as a part of the CUDA SDK, is excluded.
Therefore, we must add it to the LD_LIBRARY_PATH manually in our
container build stage.

Author: adamcavendish

.github/workflows/ci_linux.yml

@@ -44,10 +44,10 @@ jobs:
       - name: Clippy
         env:
           RUSTFLAGS: -Dwarnings
-        run: cargo clippy --workspace --exclude "optix*" --exclude "path_tracer" --exclude "denoiser" --exclude "add" --exclude "ex*" --exclude "cudnn*"
+        run: cargo clippy --workspace --exclude "optix*" --exclude "path_tracer" --exclude "denoiser" --exclude "ex*" --exclude "cudnn*"
       - name: Build
-        run: cargo build --workspace --exclude "optix*" --exclude "path_tracer" --exclude "denoiser" --exclude "add" --exclude "ex*" --exclude "cudnn*"
+        run: cargo build --workspace --exclude "optix*" --exclude "path_tracer" --exclude "denoiser" --exclude "ex*" --exclude "cudnn*"
       - name: Check documentation
         env:
           RUSTDOCFLAGS: -Dwarnings
-        run: cargo doc --workspace --all-features --document-private-items --no-deps --exclude "optix*" --exclude "path_tracer" --exclude "denoiser" --exclude "add" --exclude "ex*" --exclude "cudnn*" --exclude "cust_raw"
+        run: cargo doc --workspace --all-features --document-private-items --no-deps --exclude "optix*" --exclude "path_tracer" --exclude "denoiser" --exclude "ex*" --exclude "cudnn*" --exclude "cust_raw"

container/rockylinux9-cuda12/Dockerfile

@@ -38,5 +38,8 @@ WORKDIR /data/Rust-CUDA
 RUN rustup show
 RUN rm -f "rust-toolchain.toml"
 
+# Add nvvm to LD_LIBRARY_PATH.
+ENV LD_LIBRARY_PATH="/usr/local/cuda/nvvm/lib64:${LD_LIBRARY_PATH}"
+
 ENV LLVM_LINK_STATIC=1
 ENV RUST_LOG=info

container/ubuntu22-cuda11/Dockerfile

@@ -40,5 +40,8 @@ WORKDIR /data/Rust-CUDA
 RUN rustup show
 RUN rm -f "rust-toolchain.toml"
 
+# Add nvvm to LD_LIBRARY_PATH.
+ENV LD_LIBRARY_PATH="/usr/local/cuda/nvvm/lib64:${LD_LIBRARY_PATH}"
+
 ENV LLVM_LINK_STATIC=1
 ENV RUST_LOG=info

container/ubuntu22-cuda12/Dockerfile

@@ -40,5 +40,8 @@ WORKDIR /data/Rust-CUDA
 RUN rustup show
 RUN rm -f "rust-toolchain.toml"
 
+# Add nvvm to LD_LIBRARY_PATH.
+ENV LD_LIBRARY_PATH="/usr/local/cuda/nvvm/lib64:${LD_LIBRARY_PATH}"
+
 ENV LLVM_LINK_STATIC=1
 ENV RUST_LOG=info

container/ubuntu24-cuda12/Dockerfile

@@ -41,5 +41,8 @@ WORKDIR /data/Rust-CUDA
 RUN rustup show
 RUN rm -f "rust-toolchain.toml"
 
+# Add nvvm to LD_LIBRARY_PATH.
+ENV LD_LIBRARY_PATH="/usr/local/cuda/nvvm/lib64:${LD_LIBRARY_PATH}"
+
 ENV LLVM_LINK_STATIC=1
 ENV RUST_LOG=info