Compiler Explorer, Dist Builds, and Standalone Enzyme Build Instructions

./x.py test --stage 1 tests/ui/autodiff ./x.py test --stage 1 tests/ui/feature-gates/feature-gate-autodiff.rs ``` Autodiff is still experimental, so if you want to use it in your own projects, you will need to add `lto="fat"` to your Cargo.toml and use `RUSTFLAGS="-Zautodiff=Enable" cargo +enzyme` instead of `cargo` or `cargo +nightly`. ## Compiler Explorer and dist builds Our compiler explorer instance can be updated to a newer rustc in a similar way. First, prepare a docker instance. ```bash docker run -it ubuntu:22.04 export CC=clang CXX=clang++ apt update apt install wget vim python3 git curl libssl-dev pkg-config lld ninja-build cmake clang build-essential ``` Then build rustc in a slightly altered way: ```bash git clone --depth=1 https://github.com/rust-lang/rust.git cd rust ./configure --enable-llvm-link-shared --enable-llvm-plugins --enable-llvm-enzyme --release-channel=nightly --enable-llvm-assertions --enable-clang --enable-lld --enable-option-checking --enable-ninja --disable-docs ./x dist ``` We then copy the tarball to our host. The dockerid is the newest entry under `docker ps -a`. ```bash docker cp <dockerid>:/rust/build/dist/rust-nightly-x86_64-unknown-linux-gnu.tar.gz rust-nightly-x86_64-unknown-linux-gnu.tar.gz ``` Afterwards we can create a new (pre-release) tag on the EnzymeAD/rust repository and make a PR against the EnzymeAD/enzyme-explorer repository to update the tag. Remember to ping `tgymnich` on the PR to run his update script. Note: We should archive EnzymeAD/rust and update the instructions here. The explorer should soon be able to get the rustc toolchain from the official rust servers. ## Build instruction for Enzyme itself Following the Rust build instruction above will build LLVMEnzyme, LLDEnzyme, and ClangEnzyme along with the Rust compiler. We recommend that approach, if you just want to use any of them and have no experience with cmake. However, if you prefer to just build Enzyme without Rust, then these instructions might help. ```bash git clone --depth=1 git@github.com:llvm/llvm-project.git cd llvm-project mkdir build cd build cmake -G Ninja ../llvm -DLLVM_TARGETS_TO_BUILD="host" -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_ENABLE_RUNTIMES="openmp" -DLLVM_ENABLE_PLUGINS=ON -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=. ninja ninja install ``` This gives you a working LLVM build, now we can continue with building Enzyme. Leave the `llvm-project` folder, and execute the following commands: ```bash git clone git@github.com:EnzymeAD/Enzyme.git cd Enzyme/enzyme mkdir build cd build cmake .. -G Ninja -DLLVM_DIR=<YourLocalPath>/llvm-project/build/lib/cmake/llvm/ -DLLVM_EXTERNAL_LIT=<YourLocalPath>/llvm-project/llvm/utils/lit/lit.py -DCMAKE_BUILD_TYPE=Release -DCMAKE_EXPORT_COMPILE_COMMANDS=YES -DBUILD_SHARED_LIBS=ON ninja ``` This will build Enzyme, and you can find it in `Enzyme/enzyme/build/lib/<LLD/Clang/LLVM>Enzyme.so`. (Endings might differ based on your OS).

This section details how to update the compiler explorer instance with a newer rustc. It covers preparing a Docker instance, building rustc in a modified manner, copying the resulting tarball, and updating the EnzymeAD/rust repository. Additionally, it offers instructions for building Enzyme independently of Rust. This involves cloning the LLVM project, configuring and building it with CMake, and subsequently building Enzyme using the LLVM build.