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Rollup merge of #116791 - WaffleLapkin:unparallel-backends, r=oli-obk

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Allow codegen backends to opt-out of parallel codegen

This makes it a bit easier to write cursed codegen backends.
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Jubilee 2024-03-11 09:29:31 -07:00 committed by GitHub
commit 88d387b263
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4 changed files with 16 additions and 4 deletions
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9
compiler/rustc_codegen_ssa/src/back/write.rs
View File

@ -374,6 +374,10 @@ pub struct CodegenContext<B: WriteBackendMethods> {
pub incr_comp_session_dir: Option<PathBuf>,
/// Channel back to the main control thread to send messages to
pub coordinator_send: Sender<Box<dyn Any + Send>>,
/// `true` if the codegen should be run in parallel.
///
/// Depends on [`CodegenBackend::supports_parallel()`] and `-Zno_parallel_backend`.
pub parallel: bool,
}
impl<B: WriteBackendMethods> CodegenContext<B> {
@ -1152,6 +1156,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
target_arch: tcx.sess.target.arch.to_string(),
split_debuginfo: tcx.sess.split_debuginfo(),
split_dwarf_kind: tcx.sess.opts.unstable_opts.split_dwarf_kind,
parallel: backend.supports_parallel() && !sess.opts.unstable_opts.no_parallel_backend,
};
// This is the "main loop" of parallel work happening for parallel codegen.
@ -1422,7 +1427,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
.binary_search_by_key(&cost, |&(_, cost)| cost)
.unwrap_or_else(|e| e);
work_items.insert(insertion_index, (work, cost));
if !cgcx.opts.unstable_opts.no_parallel_llvm {
if cgcx.parallel {
helper.request_token();
}
}
@ -1545,7 +1550,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
};
work_items.insert(insertion_index, (llvm_work_item, cost));
if !cgcx.opts.unstable_opts.no_parallel_llvm {
if cgcx.parallel {
helper.request_token();
}
assert_eq!(main_thread_state, MainThreadState::Codegenning);

7
compiler/rustc_codegen_ssa/src/traits/backend.rs
View File

@ -111,6 +111,13 @@ pub trait CodegenBackend {
codegen_results: CodegenResults,
outputs: &OutputFilenames,
) -> Result<(), ErrorGuaranteed>;
/// Returns `true` if this backend can be safely called from multiple threads.
///
/// Defaults to `true`.
fn supports_parallel(&self) -> bool {
true
}
}
pub trait ExtraBackendMethods:

2
compiler/rustc_interface/src/tests.rs
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@ -685,7 +685,7 @@ fn test_unstable_options_tracking_hash() {
untracked!(nll_facts, true);
untracked!(no_analysis, true);
untracked!(no_leak_check, true);
untracked!(no_parallel_llvm, true);
untracked!(no_parallel_backend, true);
untracked!(parse_only, true);
// `pre_link_arg` is omitted because it just forwards to `pre_link_args`.
untracked!(pre_link_args, vec![String::from("abc"), String::from("def")]);

2
compiler/rustc_session/src/options.rs
View File

@ -1772,7 +1772,7 @@ options! {
"disable the 'leak check' for subtyping; unsound, but useful for tests"),
no_link: bool = (false, parse_no_flag, [TRACKED],
"compile without linking"),
no_parallel_llvm: bool = (false, parse_no_flag, [UNTRACKED],
no_parallel_backend: bool = (false, parse_no_flag, [UNTRACKED],
"run LLVM in non-parallel mode (while keeping codegen-units and ThinLTO)"),
no_profiler_runtime: bool = (false, parse_no_flag, [TRACKED],
"prevent automatic injection of the profiler_builtins crate"),