rust/compiler/rustc_codegen_ssa
bors 1b3a5f29dd Auto merge of #91125 - eskarn:llvm-passes-plugin-support, r=nagisa
Allow loading LLVM plugins with both legacy and new pass manager

Opening a draft PR to get feedback and start discussion on this feature. There is already a codegen option `passes` which allow giving a list of LLVM pass names, however we currently can't use a LLVM pass plugin (as described here : https://llvm.org/docs/WritingAnLLVMPass.html), the only available passes are the LLVM built-in ones.

The proposed modification would be to add another codegen option `pass-plugins`, which can be set with a list of paths to shared library files. These libraries are loaded using the LLVM function `PassPlugin::Load`, which calls the expected symbol `lvmGetPassPluginInfo`, and register the pipeline parsing and optimization callbacks.

An example usage with a single plugin and 3 passes would look like this in the `.cargo/config`:

```toml
rustflags = [
    "-C", "pass-plugins=/tmp/libLLVMPassPlugin",
    "-C", "passes=pass1 pass2 pass3",
]
```
This would give the same functionality as the opt LLVM tool directly integrated in rust build system.

Additionally, we can also not specify the `passes` option, and use a plugin which inserts passes in the optimization pipeline, as one could do using clang.
2021-12-30 02:53:09 +00:00
..
src Auto merge of #91125 - eskarn:llvm-passes-plugin-support, r=nagisa 2021-12-30 02:53:09 +00:00
Cargo.toml Use object crate for .rustc metadata generation 2021-12-07 09:39:05 +01:00
README.md mv compiler to compiler/ 2020-08-30 18:45:07 +03:00

Please read the rustc-dev-guide chapter on Backend Agnostic Codegen.