rust/compiler/rustc_codegen_llvm
bors a1411de9de Auto merge of #86267 - ZuseZ4:master, r=nagisa
Allow loading of llvm plugins on nightly

Based on a discussion in  #82734 / with `@wsmoses.`
Mainly moves [this](0149bc4e7e) behind a -Z flag, so it can only be used on nightly,
as requested by `@nagisa` in https://github.com/rust-lang/rust/issues/82734#issuecomment-835863940

This change allows loading of llvm plugins like Enzyme.
Right now it also requires a shared library LLVM build of rustc for symbol resolution.

```rust
// test.rs
extern { fn __enzyme_autodiff(_: usize, ...) -> f64; }

fn square(x : f64) -> f64 {
   return x * x;
}

fn main() {
   unsafe {
      println!("Hello, world {} {}!", square(3.0), __enzyme_autodiff(square as usize, 3.0));
   }
}
```
```
./rustc test.rs -Z llvm-plugins="./LLVMEnzyme-12.so" -C passes="enzyme"
./test
Hello, world 9 6!
```

I will try to figure out how to simplify the usage and get this into stable in a later iteration,
but having this on nightly will already help testing further steps.
2021-06-26 19:20:41 +00:00
..
src Auto merge of #86267 - ZuseZ4:master, r=nagisa 2021-06-26 19:20:41 +00:00
Cargo.toml Drop metadata_encoding_version. 2021-06-01 21:12:27 +02:00
README.md mv compiler to compiler/ 2020-08-30 18:45:07 +03:00

The codegen crate contains the code to convert from MIR into LLVM IR, and then from LLVM IR into machine code. In general it contains code that runs towards the end of the compilation process.

For more information about how codegen works, see the rustc dev guide.