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Rollup merge of #143388 - bjorn3:lto_refactors, r=compiler-errors

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Various refactors to the LTO handling code

In particular reducing the sharing of code paths between fat and thin-LTO and making the fat LTO implementation more self-contained. This also moves some autodiff handling out of cg_ssa into cg_llvm given that Enzyme only works with LLVM anyway and an implementation for another backend may do things entirely differently. This will also make it a bit easier to split LTO handling out of the coordinator thread main loop into a separate loop, which should reduce the complexity of the coordinator thread.
This commit is contained in:
León Orell Valerian Liehr
2025-07-17 03:58:28 +02:00
committed by GitHub
parent 9ac88eabed 21026cae8d
commit be5f8f299d
13 changed files with 154 additions and 240 deletions
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49
compiler/rustc_codegen_llvm/src/lib.rs
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@@ -26,11 +26,11 @@ use std::mem::ManuallyDrop;
use back::owned_target_machine::OwnedTargetMachine;
use back::write::{create_informational_target_machine, create_target_machine};
use context::SimpleCx;
use errors::{AutoDiffWithoutLTO, ParseTargetMachineConfig};
use errors::ParseTargetMachineConfig;
use llvm_util::target_config;
use rustc_ast::expand::allocator::AllocatorKind;
use rustc_ast::expand::autodiff_attrs::AutoDiffItem;
use rustc_codegen_ssa::back::lto::{LtoModuleCodegen, SerializedModule, ThinModule};
use rustc_codegen_ssa::back::lto::{SerializedModule, ThinModule};
use rustc_codegen_ssa::back::write::{
CodegenContext, FatLtoInput, ModuleConfig, TargetMachineFactoryConfig, TargetMachineFactoryFn,
};
@@ -43,7 +43,7 @@ use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
use rustc_middle::ty::TyCtxt;
use rustc_middle::util::Providers;
use rustc_session::Session;
use rustc_session::config::{Lto, OptLevel, OutputFilenames, PrintKind, PrintRequest};
use rustc_session::config::{OptLevel, OutputFilenames, PrintKind, PrintRequest};
use rustc_span::Symbol;
mod back {
@@ -174,18 +174,29 @@ impl WriteBackendMethods for LlvmCodegenBackend {
) -> Result<ModuleCodegen<Self::Module>, FatalError> {
back::write::link(cgcx, dcx, modules)
}
fn run_fat_lto(
fn run_and_optimize_fat_lto(
cgcx: &CodegenContext<Self>,
modules: Vec<FatLtoInput<Self>>,
cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>,
) -> Result<LtoModuleCodegen<Self>, FatalError> {
back::lto::run_fat(cgcx, modules, cached_modules)
diff_fncs: Vec<AutoDiffItem>,
) -> Result<ModuleCodegen<Self::Module>, FatalError> {
let mut module = back::lto::run_fat(cgcx, modules, cached_modules)?;
if !diff_fncs.is_empty() {
builder::autodiff::differentiate(&module, cgcx, diff_fncs)?;
}
let dcx = cgcx.create_dcx();
let dcx = dcx.handle();
back::lto::run_pass_manager(cgcx, dcx, &mut module, false)?;
Ok(module)
}
fn run_thin_lto(
cgcx: &CodegenContext<Self>,
modules: Vec<(String, Self::ThinBuffer)>,
cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>,
) -> Result<(Vec<LtoModuleCodegen<Self>>, Vec<WorkProduct>), FatalError> {
) -> Result<(Vec<ThinModule<Self>>, Vec<WorkProduct>), FatalError> {
back::lto::run_thin(cgcx, modules, cached_modules)
}
fn optimize(
@@ -196,14 +207,6 @@ impl WriteBackendMethods for LlvmCodegenBackend {
) -> Result<(), FatalError> {
back::write::optimize(cgcx, dcx, module, config)
}
fn optimize_fat(
cgcx: &CodegenContext<Self>,
module: &mut ModuleCodegen<Self::Module>,
) -> Result<(), FatalError> {
let dcx = cgcx.create_dcx();
let dcx = dcx.handle();
back::lto::run_pass_manager(cgcx, dcx, module, false)
}
fn optimize_thin(
cgcx: &CodegenContext<Self>,
thin: ThinModule<Self>,
@@ -212,11 +215,10 @@ impl WriteBackendMethods for LlvmCodegenBackend {
}
fn codegen(
cgcx: &CodegenContext<Self>,
dcx: DiagCtxtHandle<'_>,
module: ModuleCodegen<Self::Module>,
config: &ModuleConfig,
) -> Result<CompiledModule, FatalError> {
back::write::codegen(cgcx, dcx, module, config)
back::write::codegen(cgcx, module, config)
}
fn prepare_thin(
module: ModuleCodegen<Self::Module>,
@@ -227,19 +229,6 @@ impl WriteBackendMethods for LlvmCodegenBackend {
fn serialize_module(module: ModuleCodegen<Self::Module>) -> (String, Self::ModuleBuffer) {
(module.name, back::lto::ModuleBuffer::new(module.module_llvm.llmod()))
}
/// Generate autodiff rules
fn autodiff(
cgcx: &CodegenContext<Self>,
module: &ModuleCodegen<Self::Module>,
diff_fncs: Vec<AutoDiffItem>,
config: &ModuleConfig,
) -> Result<(), FatalError> {
if cgcx.lto != Lto::Fat {
let dcx = cgcx.create_dcx();
return Err(dcx.handle().emit_almost_fatal(AutoDiffWithoutLTO));
}
builder::autodiff::differentiate(module, cgcx, diff_fncs, config)
}
}
impl LlvmCodegenBackend {