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Rollup merge of #147888 - ZuseZ4:autodiff-with-download-ci, r=jieyouxu

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enzyme/autodiff is compatible with download-ci=true

To my surprise autodiff just works out of the box with download-ci=true. Thanks to all the bootstrap people who over the past helped me to link properly against the sysroot LLVM, which seems to pay off here.
That also helps with enabling Rust in Enzyme CI, since CCache for some reason doesn't seem to cache LLVM correctly on their runners.

I verified that this works with
` ./configure --release-channel=nightly --enable-llvm-enzyme --enable-option-checking --disable-docs --enable-llvm-assertions --set llvm.download-ci-llvm=true`. However, shouldn't download-ci-llvm already be the default? Why do I still have to manually set it with this pr?

I tested it afterwards with
`./x.py test --stage 1 tests/codegen-llvm/autodiff`

r? bootstrap

closes https://github.com/rust-lang/rust/issues/147535
This commit is contained in:
Stuart Cook 2025-10-20 22:30:54 +11:00 • committed by GitHub
commit d376a496f8
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4 changed files with 10 additions and 6 deletions
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3
src/bootstrap/src/core/config/toml/llvm.rs
View file

@ -117,7 +117,7 @@ pub fn check_incompatible_options_for_ci_llvm(
enable_warnings,
download_ci_llvm: _,
build_config,
enzyme,
enzyme: _,
} = ci_llvm_config;
err!(current_llvm_config.optimize, optimize);
@ -139,7 +139,6 @@ pub fn check_incompatible_options_for_ci_llvm(
err!(current_llvm_config.clang, clang);
err!(current_llvm_config.build_config, build_config);
err!(current_llvm_config.plugins, plugins);
err!(current_llvm_config.enzyme, enzyme);
warn!(current_llvm_config.enable_warnings, enable_warnings);

5
src/bootstrap/src/utils/change_tracker.rs
View file

@ -571,4 +571,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
severity: ChangeSeverity::Warning,
summary: "`rust.lld = true` no longer automatically causes the `x86_64-unknown-linux-gnu` target to default into using the self-contained LLD linker. This target now uses the LLD linker by default. To opt out, set `target.x86_64-unknown-linux-gnu.default-linker-linux-override = 'off'`.",
},
ChangeInfo {
change_id: 147888,
severity: ChangeSeverity::Info,
summary: "`llvm.enzyme` now works with `download-ci-llvm=true`.",
},
];

2
src/doc/rustc-dev-guide/src/autodiff/debugging.md
View file

@ -25,7 +25,7 @@ The actual numbers will depend on your code.
## 2) Check your llvm-ir reproducer
To confirm that your previous step worked, we will use llvm's `opt` tool. find your path to the opt binary, with a path similar to `<some_dir>/rust/build/<x86/arm/...-target-triple>/build/bin/opt`. also find `llvmenzyme-19.<so/dll/dylib>` path, similar to `/rust/build/target-triple/enzyme/build/enzyme/llvmenzyme-19`. Please keep in mind that llvm frequently updates it's llvm backend, so the version number might be higher (20, 21, ...). Once you have both, run the following command:
To confirm that your previous step worked, we will use llvm's `opt` tool. Find your path to the opt binary, with a path similar to `<some_dir>/rust/build/<x86/arm/...-target-triple>/ci-llvm/bin/opt`. If you build LLVM from source, you'll likely need to replace `ci-llvm` with `build`. Also find `llvmenzyme-21.<so/dll/dylib>` path, similar to `/rust/build/target-triple/enzyme/build/enzyme/llvmenzyme-21`. Please keep in mind that llvm frequently updates it's llvm backend, so the version number might be higher (20, 21, ...). Once you have both, run the following command:
```sh
<path/to/opt> out.ll -load-pass-plugin=/path/to/build/<target-triple>/stage1/lib/libEnzyme-21.so -passes="enzyme" -enzyme-strict-aliasing=0 -s

6
src/doc/rustc-dev-guide/src/autodiff/installation.md
View file

@ -8,7 +8,7 @@ First you need to clone and configure the Rust repository:
```bash
git clone git@github.com:rust-lang/rust
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
./configure --release-channel=nightly --enable-llvm-enzyme --enable-llvm-assertions --enable-option-checking --disable-docs --set llvm.download-ci-llvm=true
```
Afterwards you can build rustc using:
@ -47,7 +47,7 @@ Then build rustc in a slightly altered way:
```bash
git clone https://github.com/rust-lang/rust
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
./configure --release-channel=nightly --enable-llvm-enzyme --enable-llvm-assertions --enable-option-checking --disable-docs --set llvm.download-ci-llvm=true
./x dist
```
We then copy the tarball to our host. The dockerid is the newest entry under `docker ps -a`.
@ -84,5 +84,5 @@ 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 will build Enzyme, and you can find it in `Enzyme/enzyme/build/lib/<LLD/Clang/LLVM/lib>Enzyme.so`. (Endings might differ based on your OS).