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Remove support for -Zcombine-cgu

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Nobody seems to actually use this, while still adding some extra
complexity to the already rather complex codegen coordinator code.
It is also not supported by any backend other than the LLVM backend.
This commit is contained in:
bjorn3
2025-07-06 18:03:07 +00:00
parent fe2eeabe27
commit 948f7798d7
7 changed files with 6 additions and 91 deletions
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42
compiler/rustc_codegen_ssa/src/back/write.rs
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@@ -797,10 +797,6 @@ pub(crate) enum WorkItemResult<B: WriteBackendMethods> {
/// The backend has finished compiling a CGU, nothing more required.
Finished(CompiledModule),
/// The backend has finished compiling a CGU, which now needs linking
/// because `-Zcombine-cgu` was specified.
NeedsLink(ModuleCodegen<B::Module>),
/// The backend has finished compiling a CGU, which now needs to go through
/// fat LTO.
NeedsFatLto(FatLtoInput<B>),
@@ -884,7 +880,10 @@ fn execute_optimize_work_item<B: ExtraBackendMethods>(
};
match lto_type {
ComputedLtoType::No => finish_intra_module_work(cgcx, module, module_config),
ComputedLtoType::No => {
let module = B::codegen(cgcx, module, module_config)?;
Ok(WorkItemResult::Finished(module))
}
ComputedLtoType::Thin => {
let (name, thin_buffer) = B::prepare_thin(module, false);
if let Some(path) = bitcode {
@@ -1024,20 +1023,8 @@ fn execute_thin_lto_work_item<B: ExtraBackendMethods>(
module_config: &ModuleConfig,
) -> Result<WorkItemResult<B>, FatalError> {
let module = B::optimize_thin(cgcx, module)?;
finish_intra_module_work(cgcx, module, module_config)
}
fn finish_intra_module_work<B: ExtraBackendMethods>(
cgcx: &CodegenContext<B>,
module: ModuleCodegen<B::Module>,
module_config: &ModuleConfig,
) -> Result<WorkItemResult<B>, FatalError> {
if !cgcx.opts.unstable_opts.combine_cgu || module.kind == ModuleKind::Allocator {
let module = B::codegen(cgcx, module, module_config)?;
Ok(WorkItemResult::Finished(module))
} else {
Ok(WorkItemResult::NeedsLink(module))
}
let module = B::codegen(cgcx, module, module_config)?;
Ok(WorkItemResult::Finished(module))
}
/// Messages sent to the coordinator.
@@ -1343,7 +1330,6 @@ fn start_executing_work<B: ExtraBackendMethods>(
// through codegen and LLVM.
let mut compiled_modules = vec![];
let mut compiled_allocator_module = None;
let mut needs_link = Vec::new();
let mut needs_fat_lto = Vec::new();
let mut needs_thin_lto = Vec::new();
let mut lto_import_only_modules = Vec::new();
@@ -1625,7 +1611,6 @@ fn start_executing_work<B: ExtraBackendMethods>(
Ok(WorkItemResult::Finished(compiled_module)) => {
match compiled_module.kind {
ModuleKind::Regular => {
assert!(needs_link.is_empty());
compiled_modules.push(compiled_module);
}
ModuleKind::Allocator => {
@@ -1634,10 +1619,6 @@ fn start_executing_work<B: ExtraBackendMethods>(
}
}
}
Ok(WorkItemResult::NeedsLink(module)) => {
assert!(compiled_modules.is_empty());
needs_link.push(module);
}
Ok(WorkItemResult::NeedsFatLto(fat_lto_input)) => {
assert!(!started_lto);
assert!(needs_thin_lto.is_empty());
@@ -1674,17 +1655,6 @@ fn start_executing_work<B: ExtraBackendMethods>(
return Err(());
}
let needs_link = mem::take(&mut needs_link);
if !needs_link.is_empty() {
assert!(compiled_modules.is_empty());
let dcx = cgcx.create_dcx();
let dcx = dcx.handle();
let module = B::run_link(&cgcx, dcx, needs_link).map_err(|_| ())?;
let module =
B::codegen(&cgcx, module, cgcx.config(ModuleKind::Regular)).map_err(|_| ())?;
compiled_modules.push(module);
}
// Drop to print timings
drop(llvm_start_time);