bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

Auto merge of #91125 - eskarn:llvm-passes-plugin-support, r=nagisa

Browse source 
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.
This commit is contained in:
bors 2021-12-30 02:53:09 +00:00
commit 1b3a5f29dd
6 changed files with 57 additions and 26 deletions
Download patch file Download diff file Expand all files Collapse all files

7
compiler/rustc_codegen_llvm/src/back/lto.rs
View file

@ -3,7 +3,7 @@ use crate::back::write::{
};
use crate::llvm::archive_ro::ArchiveRO;
use crate::llvm::{self, build_string, False, True};
use crate::{LlvmCodegenBackend, ModuleLlvm};
use crate::{llvm_util, LlvmCodegenBackend, ModuleLlvm};
use rustc_codegen_ssa::back::lto::{LtoModuleCodegen, SerializedModule, ThinModule, ThinShared};
use rustc_codegen_ssa::back::symbol_export;
use rustc_codegen_ssa::back::write::{
@ -596,7 +596,10 @@ pub(crate) fn run_pass_manager(
// tools/lto/LTOCodeGenerator.cpp
debug!("running the pass manager");
unsafe {
if write::should_use_new_llvm_pass_manager(cgcx, config) {
if llvm_util::should_use_new_llvm_pass_manager(
&config.new_llvm_pass_manager,
&cgcx.target_arch,
) {
let opt_stage = if thin { llvm::OptStage::ThinLTO } else { llvm::OptStage::FatLTO };
let opt_level = config.opt_level.unwrap_or(config::OptLevel::No);
write::optimize_with_new_llvm_pass_manager(