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use crate::{ModuleCodegen, ModuleKind, CachedModuleCodegen, CompiledModule, CrateInfo,
CodegenResults, RLIB_BYTECODE_EXTENSION};
use super::linker::LinkerInfo;
use super::lto::{self, SerializedModule};
use super::link::{self, remove, get_linker};
use super::command::Command;
use super::symbol_export::ExportedSymbols;
use crate::traits::*;
use rustc_incremental::{copy_cgu_workproducts_to_incr_comp_cache_dir,
in_incr_comp_dir, in_incr_comp_dir_sess};
use rustc::dep_graph::{WorkProduct, WorkProductId, WorkProductFileKind};
use rustc::dep_graph::cgu_reuse_tracker::CguReuseTracker;
use rustc::middle::cstore::EncodedMetadata;
use rustc::session::config::{self, OutputFilenames, OutputType, Passes, Lto,
Sanitizer, SwitchWithOptPath};
use rustc::session::Session;
use rustc::util::nodemap::FxHashMap;
use rustc::hir::def_id::{CrateNum, LOCAL_CRATE};
use rustc::ty::TyCtxt;
use rustc::util::common::{time_depth, set_time_depth, print_time_passes_entry};
use rustc::util::profiling::SelfProfiler;
use rustc_fs_util::link_or_copy;
use rustc_data_structures::svh::Svh;
use rustc_errors::{Handler, Level, DiagnosticBuilder, FatalError, DiagnosticId};
use rustc_errors::emitter::{Emitter};
use rustc_target::spec::MergeFunctions;
use syntax::attr;
use syntax::ext::hygiene::ExpnId;
use syntax_pos::MultiSpan;
use syntax_pos::symbol::{Symbol, sym};
use jobserver::{Client, Acquired};
use std::any::Any;
use std::borrow::Cow;
use std::fs;
use std::io;
use std::mem;
use std::path::{Path, PathBuf};
use std::str;
use std::sync::Arc;
use std::sync::mpsc::{channel, Sender, Receiver};
use std::time::Instant;
use std::thread;
const PRE_LTO_BC_EXT: &str = "pre-lto.bc";
/// Module-specific configuration for `optimize_and_codegen`.
pub struct ModuleConfig {
/// Names of additional optimization passes to run.
pub passes: Vec<String>,
/// Some(level) to optimize at a certain level, or None to run
/// absolutely no optimizations (used for the metadata module).
pub opt_level: Option<config::OptLevel>,
/// Some(level) to optimize binary size, or None to not affect program size.
pub opt_size: Option<config::OptLevel>,
pub pgo_gen: SwitchWithOptPath,
pub pgo_use: Option<PathBuf>,
// Flags indicating which outputs to produce.
pub emit_pre_lto_bc: bool,
pub emit_no_opt_bc: bool,
pub emit_bc: bool,
pub emit_bc_compressed: bool,
pub emit_lto_bc: bool,
pub emit_ir: bool,
pub emit_asm: bool,
pub emit_obj: bool,
// Miscellaneous flags. These are mostly copied from command-line
// options.
pub verify_llvm_ir: bool,
pub no_prepopulate_passes: bool,
pub no_builtins: bool,
pub time_passes: bool,
pub vectorize_loop: bool,
pub vectorize_slp: bool,
pub merge_functions: bool,
pub inline_threshold: Option<usize>,
// Instead of creating an object file by doing LLVM codegen, just
// make the object file bitcode. Provides easy compatibility with
// emscripten's ecc compiler, when used as the linker.
pub obj_is_bitcode: bool,
pub no_integrated_as: bool,
pub embed_bitcode: bool,
pub embed_bitcode_marker: bool,
}
impl ModuleConfig {
fn new(passes: Vec<String>) -> ModuleConfig {
ModuleConfig {
passes,
opt_level: None,
opt_size: None,
pgo_gen: SwitchWithOptPath::Disabled,
pgo_use: None,
emit_no_opt_bc: false,
emit_pre_lto_bc: false,
emit_bc: false,
emit_bc_compressed: false,
emit_lto_bc: false,
emit_ir: false,
emit_asm: false,
emit_obj: false,
obj_is_bitcode: false,
embed_bitcode: false,
embed_bitcode_marker: false,
no_integrated_as: false,
verify_llvm_ir: false,
no_prepopulate_passes: false,
no_builtins: false,
time_passes: false,
vectorize_loop: false,
vectorize_slp: false,
merge_functions: false,
inline_threshold: None
}
}
fn set_flags(&mut self, sess: &Session, no_builtins: bool) {
self.verify_llvm_ir = sess.verify_llvm_ir();
self.no_prepopulate_passes = sess.opts.cg.no_prepopulate_passes;
self.no_builtins = no_builtins || sess.target.target.options.no_builtins;
self.time_passes = sess.time_extended();
self.inline_threshold = sess.opts.cg.inline_threshold;
self.obj_is_bitcode = sess.target.target.options.obj_is_bitcode ||
sess.opts.cg.linker_plugin_lto.enabled();
let embed_bitcode = sess.target.target.options.embed_bitcode ||
sess.opts.debugging_opts.embed_bitcode;
if embed_bitcode {
match sess.opts.optimize {
config::OptLevel::No |
config::OptLevel::Less => {
self.embed_bitcode_marker = embed_bitcode;
}
_ => self.embed_bitcode = embed_bitcode,
}
}
// Copy what clang does by turning on loop vectorization at O2 and
// slp vectorization at O3. Otherwise configure other optimization aspects
// of this pass manager builder.
// Turn off vectorization for emscripten, as it's not very well supported.
self.vectorize_loop = !sess.opts.cg.no_vectorize_loops &&
(sess.opts.optimize == config::OptLevel::Default ||
sess.opts.optimize == config::OptLevel::Aggressive) &&
!sess.target.target.options.is_like_emscripten;
self.vectorize_slp = !sess.opts.cg.no_vectorize_slp &&
sess.opts.optimize == config::OptLevel::Aggressive &&
!sess.target.target.options.is_like_emscripten;
// Some targets (namely, NVPTX) interact badly with the MergeFunctions
// pass. This is because MergeFunctions can generate new function calls
// which may interfere with the target calling convention; e.g. for the
// NVPTX target, PTX kernels should not call other PTX kernels.
// MergeFunctions can also be configured to generate aliases instead,
// but aliases are not supported by some backends (again, NVPTX).
// Therefore, allow targets to opt out of the MergeFunctions pass,
// but otherwise keep the pass enabled (at O2 and O3) since it can be
// useful for reducing code size.
self.merge_functions = match sess.opts.debugging_opts.merge_functions
.unwrap_or(sess.target.target.options.merge_functions) {
MergeFunctions::Disabled => false,
MergeFunctions::Trampolines |
MergeFunctions::Aliases => {
sess.opts.optimize == config::OptLevel::Default ||
sess.opts.optimize == config::OptLevel::Aggressive
}
};
}
pub fn bitcode_needed(&self) -> bool {
self.emit_bc || self.obj_is_bitcode
|| self.emit_bc_compressed || self.embed_bitcode
}
}
/// Assembler name and command used by codegen when no_integrated_as is enabled
pub struct AssemblerCommand {
name: PathBuf,
cmd: Command,
}
// HACK(eddyb) work around `#[derive]` producing wrong bounds for `Clone`.
pub struct TargetMachineFactory<B: WriteBackendMethods>(
pub Arc<dyn Fn() -> Result<B::TargetMachine, String> + Send + Sync>,
);
impl<B: WriteBackendMethods> Clone for TargetMachineFactory<B> {
fn clone(&self) -> Self {
TargetMachineFactory(self.0.clone())
}
}
pub struct ProfileGenericActivityTimer {
profiler: Option<Arc<SelfProfiler>>,
label: Cow<'static, str>,
}
impl ProfileGenericActivityTimer {
pub fn start(
profiler: Option<Arc<SelfProfiler>>,
label: Cow<'static, str>,
) -> ProfileGenericActivityTimer {
if let Some(profiler) = &profiler {
profiler.start_activity(label.clone());
}
ProfileGenericActivityTimer {
profiler,
label,
}
}
}
impl Drop for ProfileGenericActivityTimer {
fn drop(&mut self) {
if let Some(profiler) = &self.profiler {
profiler.end_activity(self.label.clone());
}
}
}
/// Additional resources used by optimize_and_codegen (not module specific)
#[derive(Clone)]
pub struct CodegenContext<B: WriteBackendMethods> {
// Resources needed when running LTO
pub backend: B,
pub time_passes: bool,
pub profiler: Option<Arc<SelfProfiler>>,
pub lto: Lto,
pub no_landing_pads: bool,
pub save_temps: bool,
pub fewer_names: bool,
pub exported_symbols: Option<Arc<ExportedSymbols>>,
pub opts: Arc<config::Options>,
pub crate_types: Vec<config::CrateType>,
pub each_linked_rlib_for_lto: Vec<(CrateNum, PathBuf)>,
pub output_filenames: Arc<OutputFilenames>,
pub regular_module_config: Arc<ModuleConfig>,
pub metadata_module_config: Arc<ModuleConfig>,
pub allocator_module_config: Arc<ModuleConfig>,
pub tm_factory: TargetMachineFactory<B>,
pub msvc_imps_needed: bool,
pub target_pointer_width: String,
pub target_arch: String,
pub debuginfo: config::DebugInfo,
// Number of cgus excluding the allocator/metadata modules
pub total_cgus: usize,
// Handler to use for diagnostics produced during codegen.
pub diag_emitter: SharedEmitter,
// LLVM passes added by plugins.
pub plugin_passes: Vec<String>,
// LLVM optimizations for which we want to print remarks.
pub remark: Passes,
// Worker thread number
pub worker: usize,
// The incremental compilation session directory, or None if we are not
// compiling incrementally
pub incr_comp_session_dir: Option<PathBuf>,
// Used to update CGU re-use information during the thinlto phase.
pub cgu_reuse_tracker: CguReuseTracker,
// Channel back to the main control thread to send messages to
pub coordinator_send: Sender<Box<dyn Any + Send>>,
// The assembler command if no_integrated_as option is enabled, None otherwise
pub assembler_cmd: Option<Arc<AssemblerCommand>>
}
impl<B: WriteBackendMethods> CodegenContext<B> {
pub fn create_diag_handler(&self) -> Handler {
Handler::with_emitter(true, None, Box::new(self.diag_emitter.clone()))
}
pub fn config(&self, kind: ModuleKind) -> &ModuleConfig {
match kind {
ModuleKind::Regular => &self.regular_module_config,
ModuleKind::Metadata => &self.metadata_module_config,
ModuleKind::Allocator => &self.allocator_module_config,
}
}
#[inline(never)]
#[cold]
fn profiler_active<F: FnOnce(&SelfProfiler) -> ()>(&self, f: F) {
match &self.profiler {
None => bug!("profiler_active() called but there was no profiler active"),
Some(profiler) => {
f(&*profiler);
}
}
}
#[inline(always)]
pub fn profile<F: FnOnce(&SelfProfiler) -> ()>(&self, f: F) {
if unlikely!(self.profiler.is_some()) {
self.profiler_active(f)
}
}
pub fn profile_activity(
&self,
label: impl Into<Cow<'static, str>>,
) -> ProfileGenericActivityTimer {
ProfileGenericActivityTimer::start(self.profiler.clone(), label.into())
}
}
fn generate_lto_work<B: ExtraBackendMethods>(
cgcx: &CodegenContext<B>,
needs_fat_lto: Vec<FatLTOInput<B>>,
needs_thin_lto: Vec<(String, B::ThinBuffer)>,
import_only_modules: Vec<(SerializedModule<B::ModuleBuffer>, WorkProduct)>
) -> Vec<(WorkItem<B>, u64)> {
cgcx.profile(|p| p.start_activity("codegen_run_lto"));
let (lto_modules, copy_jobs) = if !needs_fat_lto.is_empty() {
assert!(needs_thin_lto.is_empty());
let lto_module = B::run_fat_lto(
cgcx,
needs_fat_lto,
import_only_modules,
)
.unwrap_or_else(|e| e.raise());
(vec![lto_module], vec![])
} else {
assert!(needs_fat_lto.is_empty());
B::run_thin_lto(cgcx, needs_thin_lto, import_only_modules)
.unwrap_or_else(|e| e.raise())
};
let result = lto_modules.into_iter().map(|module| {
let cost = module.cost();
(WorkItem::LTO(module), cost)
}).chain(copy_jobs.into_iter().map(|wp| {
(WorkItem::CopyPostLtoArtifacts(CachedModuleCodegen {
name: wp.cgu_name.clone(),
source: wp,
}), 0)
})).collect();
cgcx.profile(|p| p.end_activity("codegen_run_lto"));
result
}
pub struct CompiledModules {
pub modules: Vec<CompiledModule>,
pub metadata_module: Option<CompiledModule>,
pub allocator_module: Option<CompiledModule>,
}
fn need_crate_bitcode_for_rlib(sess: &Session) -> bool {
sess.crate_types.borrow().contains(&config::CrateType::Rlib) &&
sess.opts.output_types.contains_key(&OutputType::Exe)
}
fn need_pre_lto_bitcode_for_incr_comp(sess: &Session) -> bool {
if sess.opts.incremental.is_none() {
return false
}
match sess.lto() {
Lto::No => false,
Lto::Fat |
Lto::Thin |
Lto::ThinLocal => true,
}
}
pub fn start_async_codegen<B: ExtraBackendMethods>(
backend: B,
tcx: TyCtxt<'_>,
metadata: EncodedMetadata,
coordinator_receive: Receiver<Box<dyn Any + Send>>,
total_cgus: usize,
) -> OngoingCodegen<B> {
let sess = tcx.sess;
let crate_name = tcx.crate_name(LOCAL_CRATE);
let crate_hash = tcx.crate_hash(LOCAL_CRATE);
let no_builtins = attr::contains_name(&tcx.hir().krate().attrs, sym::no_builtins);
let subsystem = attr::first_attr_value_str_by_name(&tcx.hir().krate().attrs,
sym::windows_subsystem);
let windows_subsystem = subsystem.map(|subsystem| {
if subsystem != sym::windows && subsystem != sym::console {
tcx.sess.fatal(&format!("invalid windows subsystem `{}`, only \
`windows` and `console` are allowed",
subsystem));
}
subsystem.to_string()
});
let linker_info = LinkerInfo::new(tcx);
let crate_info = CrateInfo::new(tcx);
// Figure out what we actually need to build.
let mut modules_config = ModuleConfig::new(sess.opts.cg.passes.clone());
let mut metadata_config = ModuleConfig::new(vec![]);
let mut allocator_config = ModuleConfig::new(vec![]);
if let Some(ref sanitizer) = sess.opts.debugging_opts.sanitizer {
match *sanitizer {
Sanitizer::Address => {
modules_config.passes.push("asan".to_owned());
modules_config.passes.push("asan-module".to_owned());
}
Sanitizer::Memory => {
modules_config.passes.push("msan".to_owned())
}
Sanitizer::Thread => {
modules_config.passes.push("tsan".to_owned())
}
_ => {}
}
}
if sess.opts.debugging_opts.profile {
modules_config.passes.push("insert-gcov-profiling".to_owned())
}
modules_config.pgo_gen = sess.opts.cg.profile_generate.clone();
modules_config.pgo_use = sess.opts.cg.profile_use.clone();
modules_config.opt_level = Some(sess.opts.optimize);
modules_config.opt_size = Some(sess.opts.optimize);
// Save all versions of the bytecode if we're saving our temporaries.
if sess.opts.cg.save_temps {
modules_config.emit_no_opt_bc = true;
modules_config.emit_pre_lto_bc = true;
modules_config.emit_bc = true;
modules_config.emit_lto_bc = true;
metadata_config.emit_bc = true;
allocator_config.emit_bc = true;
}
// Emit compressed bitcode files for the crate if we're emitting an rlib.
// Whenever an rlib is created, the bitcode is inserted into the archive in
// order to allow LTO against it.
if need_crate_bitcode_for_rlib(sess) {
modules_config.emit_bc_compressed = true;
allocator_config.emit_bc_compressed = true;
}
modules_config.emit_pre_lto_bc =
need_pre_lto_bitcode_for_incr_comp(sess);
modules_config.no_integrated_as = tcx.sess.opts.cg.no_integrated_as ||
tcx.sess.target.target.options.no_integrated_as;
for output_type in sess.opts.output_types.keys() {
match *output_type {
OutputType::Bitcode => { modules_config.emit_bc = true; }
OutputType::LlvmAssembly => { modules_config.emit_ir = true; }
OutputType::Assembly => {
modules_config.emit_asm = true;
// If we're not using the LLVM assembler, this function
// could be invoked specially with output_type_assembly, so
// in this case we still want the metadata object file.
if !sess.opts.output_types.contains_key(&OutputType::Assembly) {
metadata_config.emit_obj = true;
allocator_config.emit_obj = true;
}
}
OutputType::Object => { modules_config.emit_obj = true; }
OutputType::Metadata => { metadata_config.emit_obj = true; }
OutputType::Exe => {
modules_config.emit_obj = true;
metadata_config.emit_obj = true;
allocator_config.emit_obj = true;
},
OutputType::Mir => {}
OutputType::DepInfo => {}
}
}
modules_config.set_flags(sess, no_builtins);
metadata_config.set_flags(sess, no_builtins);
allocator_config.set_flags(sess, no_builtins);
// Exclude metadata and allocator modules from time_passes output, since
// they throw off the "LLVM passes" measurement.
metadata_config.time_passes = false;
allocator_config.time_passes = false;
let (shared_emitter, shared_emitter_main) = SharedEmitter::new();
let (codegen_worker_send, codegen_worker_receive) = channel();
let coordinator_thread = start_executing_work(backend.clone(),
tcx,
&crate_info,
shared_emitter,
codegen_worker_send,
coordinator_receive,
total_cgus,
sess.jobserver.clone(),
Arc::new(modules_config),
Arc::new(metadata_config),
Arc::new(allocator_config));
OngoingCodegen {
backend,
crate_name,
crate_hash,
metadata,
windows_subsystem,
linker_info,
crate_info,
coordinator_send: tcx.tx_to_llvm_workers.lock().clone(),
codegen_worker_receive,
shared_emitter_main,
future: coordinator_thread,
output_filenames: tcx.output_filenames(LOCAL_CRATE),
}
}
fn copy_all_cgu_workproducts_to_incr_comp_cache_dir(
sess: &Session,
compiled_modules: &CompiledModules,
) -> FxHashMap<WorkProductId, WorkProduct> {
let mut work_products = FxHashMap::default();
if sess.opts.incremental.is_none() {
return work_products;
}
for module in compiled_modules.modules.iter().filter(|m| m.kind == ModuleKind::Regular) {
let mut files = vec![];
if let Some(ref path) = module.object {
files.push((WorkProductFileKind::Object, path.clone()));
}
if let Some(ref path) = module.bytecode {
files.push((WorkProductFileKind::Bytecode, path.clone()));
}
if let Some(ref path) = module.bytecode_compressed {
files.push((WorkProductFileKind::BytecodeCompressed, path.clone()));
}
if let Some((id, product)) =
copy_cgu_workproducts_to_incr_comp_cache_dir(sess, &module.name, &files) {
work_products.insert(id, product);
}
}
work_products
}
fn produce_final_output_artifacts(sess: &Session,
compiled_modules: &CompiledModules,
crate_output: &OutputFilenames) {
let mut user_wants_bitcode = false;
let mut user_wants_objects = false;
// Produce final compile outputs.
let copy_gracefully = |from: &Path, to: &Path| {
if let Err(e) = fs::copy(from, to) {
sess.err(&format!("could not copy {:?} to {:?}: {}", from, to, e));
}
};
let copy_if_one_unit = |output_type: OutputType,
keep_numbered: bool| {
if compiled_modules.modules.len() == 1 {
// 1) Only one codegen unit. In this case it's no difficulty
// to copy `foo.0.x` to `foo.x`.
let module_name = Some(&compiled_modules.modules[0].name[..]);
let path = crate_output.temp_path(output_type, module_name);
copy_gracefully(&path,
&crate_output.path(output_type));
if !sess.opts.cg.save_temps && !keep_numbered {
// The user just wants `foo.x`, not `foo.#module-name#.x`.
remove(sess, &path);
}
} else {
let ext = crate_output.temp_path(output_type, None)
.extension()
.unwrap()
.to_str()
.unwrap()
.to_owned();
if crate_output.outputs.contains_key(&output_type) {
// 2) Multiple codegen units, with `--emit foo=some_name`. We have
// no good solution for this case, so warn the user.
sess.warn(&format!("ignoring emit path because multiple .{} files \
were produced", ext));
} else if crate_output.single_output_file.is_some() {
// 3) Multiple codegen units, with `-o some_name`. We have
// no good solution for this case, so warn the user.
sess.warn(&format!("ignoring -o because multiple .{} files \
were produced", ext));
} else {
// 4) Multiple codegen units, but no explicit name. We
// just leave the `foo.0.x` files in place.
// (We don't have to do any work in this case.)
}
}
};
// Flag to indicate whether the user explicitly requested bitcode.
// Otherwise, we produced it only as a temporary output, and will need
// to get rid of it.
for output_type in crate_output.outputs.keys() {
match *output_type {
OutputType::Bitcode => {
user_wants_bitcode = true;
// Copy to .bc, but always keep the .0.bc. There is a later
// check to figure out if we should delete .0.bc files, or keep
// them for making an rlib.
copy_if_one_unit(OutputType::Bitcode, true);
}
OutputType::LlvmAssembly => {
copy_if_one_unit(OutputType::LlvmAssembly, false);
}
OutputType::Assembly => {
copy_if_one_unit(OutputType::Assembly, false);
}
OutputType::Object => {
user_wants_objects = true;
copy_if_one_unit(OutputType::Object, true);
}
OutputType::Mir |
OutputType::Metadata |
OutputType::Exe |
OutputType::DepInfo => {}
}
}
// Clean up unwanted temporary files.
// We create the following files by default:
// - #crate#.#module-name#.bc
// - #crate#.#module-name#.o
// - #crate#.crate.metadata.bc
// - #crate#.crate.metadata.o
// - #crate#.o (linked from crate.##.o)
// - #crate#.bc (copied from crate.##.bc)
// We may create additional files if requested by the user (through
// `-C save-temps` or `--emit=` flags).
if !sess.opts.cg.save_temps {
// Remove the temporary .#module-name#.o objects. If the user didn't
// explicitly request bitcode (with --emit=bc), and the bitcode is not
// needed for building an rlib, then we must remove .#module-name#.bc as
// well.
// Specific rules for keeping .#module-name#.bc:
// - If the user requested bitcode (`user_wants_bitcode`), and
// codegen_units > 1, then keep it.
// - If the user requested bitcode but codegen_units == 1, then we
// can toss .#module-name#.bc because we copied it to .bc earlier.
// - If we're not building an rlib and the user didn't request
// bitcode, then delete .#module-name#.bc.
// If you change how this works, also update back::link::link_rlib,
// where .#module-name#.bc files are (maybe) deleted after making an
// rlib.
let needs_crate_object = crate_output.outputs.contains_key(&OutputType::Exe);
let keep_numbered_bitcode = user_wants_bitcode && sess.codegen_units() > 1;
let keep_numbered_objects = needs_crate_object ||
(user_wants_objects && sess.codegen_units() > 1);
for module in compiled_modules.modules.iter() {
if let Some(ref path) = module.object {
if !keep_numbered_objects {
remove(sess, path);
}
}
if let Some(ref path) = module.bytecode {
if !keep_numbered_bitcode {
remove(sess, path);
}
}
}
if !user_wants_bitcode {
if let Some(ref metadata_module) = compiled_modules.metadata_module {
if let Some(ref path) = metadata_module.bytecode {
remove(sess, &path);
}
}
if let Some(ref allocator_module) = compiled_modules.allocator_module {
if let Some(ref path) = allocator_module.bytecode {
remove(sess, path);
}
}
}
}
// We leave the following files around by default:
// - #crate#.o
// - #crate#.crate.metadata.o
// - #crate#.bc
// These are used in linking steps and will be cleaned up afterward.
}
pub fn dump_incremental_data(_codegen_results: &CodegenResults) {
// FIXME(mw): This does not work at the moment because the situation has
// become more complicated due to incremental LTO. Now a CGU
// can have more than two caching states.
// println!("[incremental] Re-using {} out of {} modules",
// codegen_results.modules.iter().filter(|m| m.pre_existing).count(),
// codegen_results.modules.len());
}
pub enum WorkItem<B: WriteBackendMethods> {
/// Optimize a newly codegened, totally unoptimized module.
Optimize(ModuleCodegen<B::Module>),
/// Copy the post-LTO artifacts from the incremental cache to the output
/// directory.
CopyPostLtoArtifacts(CachedModuleCodegen),
/// Performs (Thin)LTO on the given module.
LTO(lto::LtoModuleCodegen<B>),
}
impl<B: WriteBackendMethods> WorkItem<B> {
pub fn module_kind(&self) -> ModuleKind {
match *self {
WorkItem::Optimize(ref m) => m.kind,
WorkItem::CopyPostLtoArtifacts(_) |
WorkItem::LTO(_) => ModuleKind::Regular,
}
}
pub fn name(&self) -> String {
match *self {
WorkItem::Optimize(ref m) => format!("optimize: {}", m.name),
WorkItem::CopyPostLtoArtifacts(ref m) => format!("copy post LTO artifacts: {}", m.name),
WorkItem::LTO(ref m) => format!("lto: {}", m.name()),
}
}
}
enum WorkItemResult<B: WriteBackendMethods> {
Compiled(CompiledModule),
NeedsFatLTO(FatLTOInput<B>),
NeedsThinLTO(String, B::ThinBuffer),
}
pub enum FatLTOInput<B: WriteBackendMethods> {
Serialized {
name: String,
buffer: B::ModuleBuffer,
},
InMemory(ModuleCodegen<B::Module>),
}
fn execute_work_item<B: ExtraBackendMethods>(
cgcx: &CodegenContext<B>,
work_item: WorkItem<B>,
) -> Result<WorkItemResult<B>, FatalError> {
let module_config = cgcx.config(work_item.module_kind());
match work_item {
WorkItem::Optimize(module) => {
execute_optimize_work_item(cgcx, module, module_config)
}
WorkItem::CopyPostLtoArtifacts(module) => {
execute_copy_from_cache_work_item(cgcx, module, module_config)
}
WorkItem::LTO(module) => {
execute_lto_work_item(cgcx, module, module_config)
}
}
}
// Actual LTO type we end up chosing based on multiple factors.
enum ComputedLtoType {
No,
Thin,
Fat,
}
fn execute_optimize_work_item<B: ExtraBackendMethods>(
cgcx: &CodegenContext<B>,
module: ModuleCodegen<B::Module>,
module_config: &ModuleConfig,
) -> Result<WorkItemResult<B>, FatalError> {
let diag_handler = cgcx.create_diag_handler();
unsafe {
B::optimize(cgcx, &diag_handler, &module, module_config)?;
}
// After we've done the initial round of optimizations we need to
// decide whether to synchronously codegen this module or ship it
// back to the coordinator thread for further LTO processing (which
// has to wait for all the initial modules to be optimized).
// If the linker does LTO, we don't have to do it. Note that we
// keep doing full LTO, if it is requested, as not to break the
// assumption that the output will be a single module.
let linker_does_lto = cgcx.opts.cg.linker_plugin_lto.enabled();
// When we're automatically doing ThinLTO for multi-codegen-unit
// builds we don't actually want to LTO the allocator modules if
// it shows up. This is due to various linker shenanigans that
// we'll encounter later.
let is_allocator = module.kind == ModuleKind::Allocator;
// We ignore a request for full crate grath LTO if the cate type
// is only an rlib, as there is no full crate graph to process,
// that'll happen later.
//
// This use case currently comes up primarily for targets that
// require LTO so the request for LTO is always unconditionally
// passed down to the backend, but we don't actually want to do
// anything about it yet until we've got a final product.
let is_rlib = cgcx.crate_types.len() == 1
&& cgcx.crate_types[0] == config::CrateType::Rlib;
// Metadata modules never participate in LTO regardless of the lto
// settings.
let lto_type = if module.kind == ModuleKind::Metadata {
ComputedLtoType::No
} else {
match cgcx.lto {
Lto::ThinLocal if !linker_does_lto && !is_allocator
=> ComputedLtoType::Thin,
Lto::Thin if !linker_does_lto && !is_rlib
=> ComputedLtoType::Thin,
Lto::Fat if !is_rlib => ComputedLtoType::Fat,
_ => ComputedLtoType::No,
}
};
// If we're doing some form of incremental LTO then we need to be sure to
// save our module to disk first.
let bitcode = if cgcx.config(module.kind).emit_pre_lto_bc {
let filename = pre_lto_bitcode_filename(&module.name);
cgcx.incr_comp_session_dir.as_ref().map(|path| path.join(&filename))
} else {
None
};
Ok(match lto_type {
ComputedLtoType::No => {
let module = unsafe {
B::codegen(cgcx, &diag_handler, module, module_config)?
};
WorkItemResult::Compiled(module)
}
ComputedLtoType::Thin => {
let (name, thin_buffer) = B::prepare_thin(module);
if let Some(path) = bitcode {
fs::write(&path, thin_buffer.data()).unwrap_or_else(|e| {
panic!("Error writing pre-lto-bitcode file `{}`: {}",
path.display(),
e);
});
}
WorkItemResult::NeedsThinLTO(name, thin_buffer)
}
ComputedLtoType::Fat => {
match bitcode {
Some(path) => {
let (name, buffer) = B::serialize_module(module);
fs::write(&path, buffer.data()).unwrap_or_else(|e| {
panic!("Error writing pre-lto-bitcode file `{}`: {}",
path.display(),
e);
});
WorkItemResult::NeedsFatLTO(FatLTOInput::Serialized { name, buffer })
}
None => WorkItemResult::NeedsFatLTO(FatLTOInput::InMemory(module)),
}
}
})
}
fn execute_copy_from_cache_work_item<B: ExtraBackendMethods>(
cgcx: &CodegenContext<B>,
module: CachedModuleCodegen,
module_config: &ModuleConfig,
) -> Result<WorkItemResult<B>, FatalError> {
let incr_comp_session_dir = cgcx.incr_comp_session_dir
.as_ref()
.unwrap();
let mut object = None;
let mut bytecode = None;
let mut bytecode_compressed = None;
for (kind, saved_file) in &module.source.saved_files {
let obj_out = match kind {
WorkProductFileKind::Object => {
let path = cgcx.output_filenames.temp_path(OutputType::Object,
Some(&module.name));
object = Some(path.clone());
path
}
WorkProductFileKind::Bytecode => {
let path = cgcx.output_filenames.temp_path(OutputType::Bitcode,
Some(&module.name));
bytecode = Some(path.clone());
path
}
WorkProductFileKind::BytecodeCompressed => {
let path = cgcx.output_filenames.temp_path(OutputType::Bitcode,
Some(&module.name))
.with_extension(RLIB_BYTECODE_EXTENSION);
bytecode_compressed = Some(path.clone());
path
}
};
let source_file = in_incr_comp_dir(&incr_comp_session_dir,
&saved_file);
debug!("copying pre-existing module `{}` from {:?} to {}",
module.name,
source_file,
obj_out.display());
if let Err(err) = link_or_copy(&source_file, &obj_out) {
let diag_handler = cgcx.create_diag_handler();
diag_handler.err(&format!("unable to copy {} to {}: {}",
source_file.display(),
obj_out.display(),
err));
}
}
assert_eq!(object.is_some(), module_config.emit_obj);
assert_eq!(bytecode.is_some(), module_config.emit_bc);
assert_eq!(bytecode_compressed.is_some(), module_config.emit_bc_compressed);
Ok(WorkItemResult::Compiled(CompiledModule {
name: module.name,
kind: ModuleKind::Regular,
object,
bytecode,
bytecode_compressed,
}))
}
fn execute_lto_work_item<B: ExtraBackendMethods>(
cgcx: &CodegenContext<B>,
mut module: lto::LtoModuleCodegen<B>,
module_config: &ModuleConfig,
) -> Result<WorkItemResult<B>, FatalError> {
let diag_handler = cgcx.create_diag_handler();
unsafe {
let module = module.optimize(cgcx)?;
let module = B::codegen(cgcx, &diag_handler, module, module_config)?;
Ok(WorkItemResult::Compiled(module))
}
}
pub enum Message<B: WriteBackendMethods> {
Token(io::Result<Acquired>),
NeedsFatLTO {
result: FatLTOInput<B>,
worker_id: usize,
},
NeedsThinLTO {
name: String,
thin_buffer: B::ThinBuffer,
worker_id: usize,
},
Done {
result: Result<CompiledModule, ()>,
worker_id: usize,
},
CodegenDone {
llvm_work_item: WorkItem<B>,
cost: u64,
},
AddImportOnlyModule {
module_data: SerializedModule<B::ModuleBuffer>,
work_product: WorkProduct,
},
CodegenComplete,
CodegenItem,
CodegenAborted,
}
struct Diagnostic {
msg: String,
code: Option<DiagnosticId>,
lvl: Level,
}
#[derive(PartialEq, Clone, Copy, Debug)]
enum MainThreadWorkerState {
Idle,
Codegenning,
LLVMing,
}
fn start_executing_work<B: ExtraBackendMethods>(
backend: B,
tcx: TyCtxt<'_>,
crate_info: &CrateInfo,
shared_emitter: SharedEmitter,
codegen_worker_send: Sender<Message<B>>,
coordinator_receive: Receiver<Box<dyn Any + Send>>,
total_cgus: usize,
jobserver: Client,
modules_config: Arc<ModuleConfig>,
metadata_config: Arc<ModuleConfig>,
allocator_config: Arc<ModuleConfig>,
) -> thread::JoinHandle<Result<CompiledModules, ()>> {
let coordinator_send = tcx.tx_to_llvm_workers.lock().clone();
let sess = tcx.sess;
// Compute the set of symbols we need to retain when doing LTO (if we need to)
let exported_symbols = {
let mut exported_symbols = FxHashMap::default();
let copy_symbols = |cnum| {
let symbols = tcx.exported_symbols(cnum)
.iter()
.map(|&(s, lvl)| (s.symbol_name(tcx).to_string(), lvl))
.collect();
Arc::new(symbols)
};
match sess.lto() {
Lto::No => None,
Lto::ThinLocal => {
exported_symbols.insert(LOCAL_CRATE, copy_symbols(LOCAL_CRATE));
Some(Arc::new(exported_symbols))
}
Lto::Fat | Lto::Thin => {
exported_symbols.insert(LOCAL_CRATE, copy_symbols(LOCAL_CRATE));
for &cnum in tcx.crates().iter() {
exported_symbols.insert(cnum, copy_symbols(cnum));
}
Some(Arc::new(exported_symbols))
}
}
};
// First up, convert our jobserver into a helper thread so we can use normal
// mpsc channels to manage our messages and such.
// After we've requested tokens then we'll, when we can,
// get tokens on `coordinator_receive` which will
// get managed in the main loop below.
let coordinator_send2 = coordinator_send.clone();
let helper = jobserver.into_helper_thread(move |token| {
drop(coordinator_send2.send(Box::new(Message::Token::<B>(token))));
}).expect("failed to spawn helper thread");
let mut each_linked_rlib_for_lto = Vec::new();
drop(link::each_linked_rlib(sess, crate_info, &mut |cnum, path| {
if link::ignored_for_lto(sess, crate_info, cnum) {
return
}
each_linked_rlib_for_lto.push((cnum, path.to_path_buf()));
}));
let assembler_cmd = if modules_config.no_integrated_as {
// HACK: currently we use linker (gcc) as our assembler
let (linker, flavor) = link::linker_and_flavor(sess);
let (name, mut cmd) = get_linker(sess, &linker, flavor);
cmd.args(&sess.target.target.options.asm_args);
Some(Arc::new(AssemblerCommand {
name,
cmd,
}))
} else {
None
};
let ol = if tcx.sess.opts.debugging_opts.no_codegen
|| !tcx.sess.opts.output_types.should_codegen() {
// If we know that we won’t be doing codegen, create target machines without optimisation.
config::OptLevel::No
} else {
tcx.backend_optimization_level(LOCAL_CRATE)
};
let cgcx = CodegenContext::<B> {
backend: backend.clone(),
crate_types: sess.crate_types.borrow().clone(),
each_linked_rlib_for_lto,
lto: sess.lto(),
no_landing_pads: sess.no_landing_pads(),
fewer_names: sess.fewer_names(),
save_temps: sess.opts.cg.save_temps,
opts: Arc::new(sess.opts.clone()),
time_passes: sess.time_extended(),
profiler: sess.self_profiling.clone(),
exported_symbols,
plugin_passes: sess.plugin_llvm_passes.borrow().clone(),
remark: sess.opts.cg.remark.clone(),
worker: 0,
incr_comp_session_dir: sess.incr_comp_session_dir_opt().map(|r| r.clone()),
cgu_reuse_tracker: sess.cgu_reuse_tracker.clone(),
coordinator_send,
diag_emitter: shared_emitter.clone(),
output_filenames: tcx.output_filenames(LOCAL_CRATE),
regular_module_config: modules_config,
metadata_module_config: metadata_config,
allocator_module_config: allocator_config,
tm_factory: TargetMachineFactory(backend.target_machine_factory(tcx.sess, ol, false)),
total_cgus,
msvc_imps_needed: msvc_imps_needed(tcx),
target_pointer_width: tcx.sess.target.target.target_pointer_width.clone(),
target_arch: tcx.sess.target.target.arch.clone(),
debuginfo: tcx.sess.opts.debuginfo,
assembler_cmd,
};
// This is the "main loop" of parallel work happening for parallel codegen.
// It's here that we manage parallelism, schedule work, and work with
// messages coming from clients.
//
// There are a few environmental pre-conditions that shape how the system
// is set up:
//
// - Error reporting only can happen on the main thread because that's the
// only place where we have access to the compiler `Session`.
// - LLVM work can be done on any thread.
// - Codegen can only happen on the main thread.
// - Each thread doing substantial work most be in possession of a `Token`
// from the `Jobserver`.
// - The compiler process always holds one `Token`. Any additional `Tokens`
// have to be requested from the `Jobserver`.
//
// Error Reporting
// ===============
// The error reporting restriction is handled separately from the rest: We
// set up a `SharedEmitter` the holds an open channel to the main thread.
// When an error occurs on any thread, the shared emitter will send the
// error message to the receiver main thread (`SharedEmitterMain`). The
// main thread will periodically query this error message queue and emit
// any error messages it has received. It might even abort compilation if
// has received a fatal error. In this case we rely on all other threads
// being torn down automatically with the main thread.
// Since the main thread will often be busy doing codegen work, error
// reporting will be somewhat delayed, since the message queue can only be
// checked in between to work packages.
//
// Work Processing Infrastructure
// ==============================
// The work processing infrastructure knows three major actors:
//
// - the coordinator thread,
// - the main thread, and
// - LLVM worker threads
//
// The coordinator thread is running a message loop. It instructs the main
// thread about what work to do when, and it will spawn off LLVM worker
// threads as open LLVM WorkItems become available.
//
// The job of the main thread is to codegen CGUs into LLVM work package
// (since the main thread is the only thread that can do this). The main
// thread will block until it receives a message from the coordinator, upon
// which it will codegen one CGU, send it to the coordinator and block
// again. This way the coordinator can control what the main thread is
// doing.
//
// The coordinator keeps a queue of LLVM WorkItems, and when a `Token` is
// available, it will spawn off a new LLVM worker thread and let it process
// that a WorkItem. When a LLVM worker thread is done with its WorkItem,
// it will just shut down, which also frees all resources associated with
// the given LLVM module, and sends a message to the coordinator that the
// has been completed.
//
// Work Scheduling
// ===============
// The scheduler's goal is to minimize the time it takes to complete all
// work there is, however, we also want to keep memory consumption low
// if possible. These two goals are at odds with each other: If memory
// consumption were not an issue, we could just let the main thread produce
// LLVM WorkItems at full speed, assuring maximal utilization of
// Tokens/LLVM worker threads. However, since codegen usual is faster
// than LLVM processing, the queue of LLVM WorkItems would fill up and each
// WorkItem potentially holds on to a substantial amount of memory.
//
// So the actual goal is to always produce just enough LLVM WorkItems as
// not to starve our LLVM worker threads. That means, once we have enough
// WorkItems in our queue, we can block the main thread, so it does not
// produce more until we need them.
//
// Doing LLVM Work on the Main Thread
// ----------------------------------
// Since the main thread owns the compiler processes implicit `Token`, it is
// wasteful to keep it blocked without doing any work. Therefore, what we do
// in this case is: We spawn off an additional LLVM worker thread that helps
// reduce the queue. The work it is doing corresponds to the implicit
// `Token`. The coordinator will mark the main thread as being busy with
// LLVM work. (The actual work happens on another OS thread but we just care
// about `Tokens`, not actual threads).
//
// When any LLVM worker thread finishes while the main thread is marked as
// "busy with LLVM work", we can do a little switcheroo: We give the Token
// of the just finished thread to the LLVM worker thread that is working on
// behalf of the main thread's implicit Token, thus freeing up the main
// thread again. The coordinator can then again decide what the main thread
// should do. This allows the coordinator to make decisions at more points
// in time.
//
// Striking a Balance between Throughput and Memory Consumption
// ------------------------------------------------------------
// Since our two goals, (1) use as many Tokens as possible and (2) keep
// memory consumption as low as possible, are in conflict with each other,
// we have to find a trade off between them. Right now, the goal is to keep
// all workers busy, which means that no worker should find the queue empty
// when it is ready to start.
// How do we do achieve this? Good question :) We actually never know how
// many `Tokens` are potentially available so it's hard to say how much to
// fill up the queue before switching the main thread to LLVM work. Also we
// currently don't have a means to estimate how long a running LLVM worker
// will still be busy with it's current WorkItem. However, we know the
// maximal count of available Tokens that makes sense (=the number of CPU
// cores), so we can take a conservative guess. The heuristic we use here
// is implemented in the `queue_full_enough()` function.
//
// Some Background on Jobservers
// -----------------------------
// It's worth also touching on the management of parallelism here. We don't
// want to just spawn a thread per work item because while that's optimal
// parallelism it may overload a system with too many threads or violate our
// configuration for the maximum amount of cpu to use for this process. To
// manage this we use the `jobserver` crate.
//
// Job servers are an artifact of GNU make and are used to manage
// parallelism between processes. A jobserver is a glorified IPC semaphore
// basically. Whenever we want to run some work we acquire the semaphore,
// and whenever we're done with that work we release the semaphore. In this
// manner we can ensure that the maximum number of parallel workers is
// capped at any one point in time.
//
// LTO and the coordinator thread
// ------------------------------
//
// The final job the coordinator thread is responsible for is managing LTO
// and how that works. When LTO is requested what we'll to is collect all
// optimized LLVM modules into a local vector on the coordinator. Once all
// modules have been codegened and optimized we hand this to the `lto`
// module for further optimization. The `lto` module will return back a list
// of more modules to work on, which the coordinator will continue to spawn
// work for.
//
// Each LLVM module is automatically sent back to the coordinator for LTO if
// necessary. There's already optimizations in place to avoid sending work
// back to the coordinator if LTO isn't requested.
return thread::spawn(move || {
// We pretend to be within the top-level LLVM time-passes task here:
set_time_depth(1);
let max_workers = ::num_cpus::get();
let mut worker_id_counter = 0;
let mut free_worker_ids = Vec::new();
let mut get_worker_id = |free_worker_ids: &mut Vec<usize>| {
if let Some(id) = free_worker_ids.pop() {
id
} else {
let id = worker_id_counter;
worker_id_counter += 1;
id
}
};
// This is where we collect codegen units that have gone all the way
// through codegen and LLVM.
let mut compiled_modules = vec![];
let mut compiled_metadata_module = None;
let mut compiled_allocator_module = None;
let mut needs_fat_lto = Vec::new();
let mut needs_thin_lto = Vec::new();
let mut lto_import_only_modules = Vec::new();
let mut started_lto = false;
let mut codegen_aborted = false;
// This flag tracks whether all items have gone through codegens
let mut codegen_done = false;
// This is the queue of LLVM work items that still need processing.
let mut work_items = Vec::<(WorkItem<B>, u64)>::new();
// This are the Jobserver Tokens we currently hold. Does not include
// the implicit Token the compiler process owns no matter what.
let mut tokens = Vec::new();
let mut main_thread_worker_state = MainThreadWorkerState::Idle;
let mut running = 0;
let mut llvm_start_time = None;
// Run the message loop while there's still anything that needs message
// processing. Note that as soon as codegen is aborted we simply want to
// wait for all existing work to finish, so many of the conditions here
// only apply if codegen hasn't been aborted as they represent pending
// work to be done.
while !codegen_done ||
running > 0 ||
(!codegen_aborted && (
work_items.len() > 0 ||
needs_fat_lto.len() > 0 ||
needs_thin_lto.len() > 0 ||
lto_import_only_modules.len() > 0 ||
main_thread_worker_state != MainThreadWorkerState::Idle
))
{
// While there are still CGUs to be codegened, the coordinator has
// to decide how to utilize the compiler processes implicit Token:
// For codegenning more CGU or for running them through LLVM.
if !codegen_done {
if main_thread_worker_state == MainThreadWorkerState::Idle {
if !queue_full_enough(work_items.len(), running, max_workers) {
// The queue is not full enough, codegen more items:
if let Err(_) = codegen_worker_send.send(Message::CodegenItem) {
panic!("Could not send Message::CodegenItem to main thread")
}
main_thread_worker_state = MainThreadWorkerState::Codegenning;
} else {
// The queue is full enough to not let the worker
// threads starve. Use the implicit Token to do some
// LLVM work too.
let (item, _) = work_items.pop()
.expect("queue empty - queue_full_enough() broken?");
let cgcx = CodegenContext {
worker: get_worker_id(&mut free_worker_ids),
.. cgcx.clone()
};
maybe_start_llvm_timer(cgcx.config(item.module_kind()),
&mut llvm_start_time);
main_thread_worker_state = MainThreadWorkerState::LLVMing;
spawn_work(cgcx, item);
}
}
} else if codegen_aborted {
// don't queue up any more work if codegen was aborted, we're
// just waiting for our existing children to finish
} else {
// If we've finished everything related to normal codegen
// then it must be the case that we've got some LTO work to do.
// Perform the serial work here of figuring out what we're
// going to LTO and then push a bunch of work items onto our
// queue to do LTO
if work_items.len() == 0 &&
running == 0 &&
main_thread_worker_state == MainThreadWorkerState::Idle {
assert!(!started_lto);
started_lto = true;
let needs_fat_lto = mem::take(&mut needs_fat_lto);
let needs_thin_lto = mem::take(&mut needs_thin_lto);
let import_only_modules = mem::take(&mut lto_import_only_modules);
for (work, cost) in generate_lto_work(&cgcx, needs_fat_lto,
needs_thin_lto, import_only_modules) {
let insertion_index = work_items
.binary_search_by_key(&cost, |&(_, cost)| cost)
.unwrap_or_else(|e| e);
work_items.insert(insertion_index, (work, cost));
if !cgcx.opts.debugging_opts.no_parallel_llvm {
helper.request_token();
}
}
}
// In this branch, we know that everything has been codegened,
// so it's just a matter of determining whether the implicit
// Token is free to use for LLVM work.
match main_thread_worker_state {
MainThreadWorkerState::Idle => {
if let Some((item, _)) = work_items.pop() {
let cgcx = CodegenContext {
worker: get_worker_id(&mut free_worker_ids),
.. cgcx.clone()
};
maybe_start_llvm_timer(cgcx.config(item.module_kind()),
&mut llvm_start_time);
main_thread_worker_state = MainThreadWorkerState::LLVMing;
spawn_work(cgcx, item);
} else {
// There is no unstarted work, so let the main thread
// take over for a running worker. Otherwise the
// implicit token would just go to waste.
// We reduce the `running` counter by one. The
// `tokens.truncate()` below will take care of
// giving the Token back.
debug_assert!(running > 0);
running -= 1;
main_thread_worker_state = MainThreadWorkerState::LLVMing;
}
}
MainThreadWorkerState::Codegenning => {
bug!("codegen worker should not be codegenning after \
codegen was already completed")
}
MainThreadWorkerState::LLVMing => {
// Already making good use of that token
}
}
}
// Spin up what work we can, only doing this while we've got available
// parallelism slots and work left to spawn.
while !codegen_aborted && work_items.len() > 0 && running < tokens.len() {
let (item, _) = work_items.pop().unwrap();
maybe_start_llvm_timer(cgcx.config(item.module_kind()),
&mut llvm_start_time);
let cgcx = CodegenContext {
worker: get_worker_id(&mut free_worker_ids),
.. cgcx.clone()
};
spawn_work(cgcx, item);
running += 1;
}
// Relinquish accidentally acquired extra tokens
tokens.truncate(running);
// If a thread exits successfully then we drop a token associated
// with that worker and update our `running` count. We may later
// re-acquire a token to continue running more work. We may also not
// actually drop a token here if the worker was running with an
// "ephemeral token"
let mut free_worker = |worker_id| {
if main_thread_worker_state == MainThreadWorkerState::LLVMing {
main_thread_worker_state = MainThreadWorkerState::Idle;
} else {
running -= 1;
}
free_worker_ids.push(worker_id);
};
let msg = coordinator_receive.recv().unwrap();
match *msg.downcast::<Message<B>>().ok().unwrap() {
// Save the token locally and the next turn of the loop will use
// this to spawn a new unit of work, or it may get dropped
// immediately if we have no more work to spawn.
Message::Token(token) => {
match token {
Ok(token) => {
tokens.push(token);
if main_thread_worker_state == MainThreadWorkerState::LLVMing {
// If the main thread token is used for LLVM work
// at the moment, we turn that thread into a regular
// LLVM worker thread, so the main thread is free
// to react to codegen demand.
main_thread_worker_state = MainThreadWorkerState::Idle;
running += 1;
}
}
Err(e) => {
let msg = &format!("failed to acquire jobserver token: {}", e);
shared_emitter.fatal(msg);
// Exit the coordinator thread
panic!("{}", msg)
}
}
}
Message::CodegenDone { llvm_work_item, cost } => {
// We keep the queue sorted by estimated processing cost,
// so that more expensive items are processed earlier. This
// is good for throughput as it gives the main thread more
// time to fill up the queue and it avoids scheduling
// expensive items to the end.
// Note, however, that this is not ideal for memory
// consumption, as LLVM module sizes are not evenly
// distributed.
let insertion_index =
work_items.binary_search_by_key(&cost, |&(_, cost)| cost);
let insertion_index = match insertion_index {
Ok(idx) | Err(idx) => idx
};
work_items.insert(insertion_index, (llvm_work_item, cost));
if !cgcx.opts.debugging_opts.no_parallel_llvm {
helper.request_token();
}
assert!(!codegen_aborted);
assert_eq!(main_thread_worker_state,
MainThreadWorkerState::Codegenning);
main_thread_worker_state = MainThreadWorkerState::Idle;
}
Message::CodegenComplete => {
codegen_done = true;
assert!(!codegen_aborted);
assert_eq!(main_thread_worker_state,
MainThreadWorkerState::Codegenning);
main_thread_worker_state = MainThreadWorkerState::Idle;
}
// If codegen is aborted that means translation was aborted due
// to some normal-ish compiler error. In this situation we want
// to exit as soon as possible, but we want to make sure all
// existing work has finished. Flag codegen as being done, and
// then conditions above will ensure no more work is spawned but
// we'll keep executing this loop until `running` hits 0.
Message::CodegenAborted => {
assert!(!codegen_aborted);
codegen_done = true;
codegen_aborted = true;
assert_eq!(main_thread_worker_state,
MainThreadWorkerState::Codegenning);
}
Message::Done { result: Ok(compiled_module), worker_id } => {
free_worker(worker_id);
match compiled_module.kind {
ModuleKind::Regular => {
compiled_modules.push(compiled_module);
}
ModuleKind::Metadata => {
assert!(compiled_metadata_module.is_none());
compiled_metadata_module = Some(compiled_module);
}
ModuleKind::Allocator => {
assert!(compiled_allocator_module.is_none());
compiled_allocator_module = Some(compiled_module);
}
}
}
Message::NeedsFatLTO { result, worker_id } => {
assert!(!started_lto);
free_worker(worker_id);
needs_fat_lto.push(result);
}
Message::NeedsThinLTO { name, thin_buffer, worker_id } => {
assert!(!started_lto);
free_worker(worker_id);
needs_thin_lto.push((name, thin_buffer));
}
Message::AddImportOnlyModule { module_data, work_product } => {
assert!(!started_lto);
assert!(!codegen_done);
assert_eq!(main_thread_worker_state,
MainThreadWorkerState::Codegenning);
lto_import_only_modules.push((module_data, work_product));
main_thread_worker_state = MainThreadWorkerState::Idle;
}
// If the thread failed that means it panicked, so we abort immediately.
Message::Done { result: Err(()), worker_id: _ } => {
bug!("worker thread panicked");
}
Message::CodegenItem => {
bug!("the coordinator should not receive codegen requests")
}
}
}
if let Some(llvm_start_time) = llvm_start_time {
let total_llvm_time = Instant::now().duration_since(llvm_start_time);
// This is the top-level timing for all of LLVM, set the time-depth
// to zero.
set_time_depth(1);
print_time_passes_entry(cgcx.time_passes,
"LLVM passes",
total_llvm_time);
}
// Regardless of what order these modules completed in, report them to
// the backend in the same order every time to ensure that we're handing
// out deterministic results.
compiled_modules.sort_by(|a, b| a.name.cmp(&b.name));
Ok(CompiledModules {
modules: compiled_modules,
metadata_module: compiled_metadata_module,
allocator_module: compiled_allocator_module,
})
});
// A heuristic that determines if we have enough LLVM WorkItems in the
// queue so that the main thread can do LLVM work instead of codegen
fn queue_full_enough(items_in_queue: usize,
workers_running: usize,
max_workers: usize) -> bool {
// Tune me, plz.
items_in_queue > 0 &&
items_in_queue >= max_workers.saturating_sub(workers_running / 2)
}
fn maybe_start_llvm_timer(config: &ModuleConfig,
llvm_start_time: &mut Option<Instant>) {
// We keep track of the -Ztime-passes output manually,
// since the closure-based interface does not fit well here.
if config.time_passes {
if llvm_start_time.is_none() {
*llvm_start_time = Some(Instant::now());
}
}
}
}
pub const CODEGEN_WORKER_ID: usize = ::std::usize::MAX;
fn spawn_work<B: ExtraBackendMethods>(
cgcx: CodegenContext<B>,
work: WorkItem<B>
) {
let depth = time_depth();
thread::spawn(move || {
set_time_depth(depth);
// Set up a destructor which will fire off a message that we're done as
// we exit.
struct Bomb<B: ExtraBackendMethods> {
coordinator_send: Sender<Box<dyn Any + Send>>,
result: Option<WorkItemResult<B>>,
worker_id: usize,
}
impl<B: ExtraBackendMethods> Drop for Bomb<B> {
fn drop(&mut self) {
let worker_id = self.worker_id;
let msg = match self.result.take() {
Some(WorkItemResult::Compiled(m)) => {
Message::Done::<B> { result: Ok(m), worker_id }
}
Some(WorkItemResult::NeedsFatLTO(m)) => {
Message::NeedsFatLTO::<B> { result: m, worker_id }
}
Some(WorkItemResult::NeedsThinLTO(name, thin_buffer)) => {
Message::NeedsThinLTO::<B> { name, thin_buffer, worker_id }
}
None => Message::Done::<B> { result: Err(()), worker_id }
};
drop(self.coordinator_send.send(Box::new(msg)));
}
}
let mut bomb = Bomb::<B> {
coordinator_send: cgcx.coordinator_send.clone(),
result: None,
worker_id: cgcx.worker,
};
// Execute the work itself, and if it finishes successfully then flag
// ourselves as a success as well.
//
// Note that we ignore any `FatalError` coming out of `execute_work_item`,
// as a diagnostic was already sent off to the main thread - just
// surface that there was an error in this worker.
bomb.result = {
let label = work.name();
cgcx.profile(|p| p.start_activity(label.clone()));
let result = execute_work_item(&cgcx, work).ok();
cgcx.profile(|p| p.end_activity(label));
result
};
});
}
pub fn run_assembler<B: ExtraBackendMethods>(
cgcx: &CodegenContext<B>,
handler: &Handler,
assembly: &Path,
object: &Path
) {
let assembler = cgcx.assembler_cmd
.as_ref()
.expect("cgcx.assembler_cmd is missing?");
let pname = &assembler.name;
let mut cmd = assembler.cmd.clone();
cmd.arg("-c").arg("-o").arg(object).arg(assembly);
debug!("{:?}", cmd);
match cmd.output() {
Ok(prog) => {
if !prog.status.success() {
let mut note = prog.stderr.clone();
note.extend_from_slice(&prog.stdout);
handler.struct_err(&format!("linking with `{}` failed: {}",
pname.display(),
prog.status))
.note(&format!("{:?}", &cmd))
.note(str::from_utf8(&note[..]).unwrap())
.emit();
handler.abort_if_errors();
}
},
Err(e) => {
handler.err(&format!("could not exec the linker `{}`: {}", pname.display(), e));
handler.abort_if_errors();
}
}
}
enum SharedEmitterMessage {
Diagnostic(Diagnostic),
InlineAsmError(u32, String),
AbortIfErrors,
Fatal(String),
}
#[derive(Clone)]
pub struct SharedEmitter {
sender: Sender<SharedEmitterMessage>,
}
pub struct SharedEmitterMain {
receiver: Receiver<SharedEmitterMessage>,
}
impl SharedEmitter {
pub fn new() -> (SharedEmitter, SharedEmitterMain) {
let (sender, receiver) = channel();
(SharedEmitter { sender }, SharedEmitterMain { receiver })
}
pub fn inline_asm_error(&self, cookie: u32, msg: String) {
drop(self.sender.send(SharedEmitterMessage::InlineAsmError(cookie, msg)));
}
pub fn fatal(&self, msg: &str) {
drop(self.sender.send(SharedEmitterMessage::Fatal(msg.to_string())));
}
}
impl Emitter for SharedEmitter {
fn emit_diagnostic(&mut self, db: &DiagnosticBuilder<'_>) {
drop(self.sender.send(SharedEmitterMessage::Diagnostic(Diagnostic {
msg: db.message(),
code: db.code.clone(),
lvl: db.level,
})));
for child in &db.children {
drop(self.sender.send(SharedEmitterMessage::Diagnostic(Diagnostic {
msg: child.message(),
code: None,
lvl: child.level,
})));
}
drop(self.sender.send(SharedEmitterMessage::AbortIfErrors));
}
}
impl SharedEmitterMain {
pub fn check(&self, sess: &Session, blocking: bool) {
loop {
let message = if blocking {
match self.receiver.recv() {
Ok(message) => Ok(message),
Err(_) => Err(()),
}
} else {
match self.receiver.try_recv() {
Ok(message) => Ok(message),
Err(_) => Err(()),
}
};
match message {
Ok(SharedEmitterMessage::Diagnostic(diag)) => {
let handler = sess.diagnostic();
match diag.code {
Some(ref code) => {
handler.emit_with_code(&MultiSpan::new(),
&diag.msg,
code.clone(),
diag.lvl);
}
None => {
handler.emit(&MultiSpan::new(),
&diag.msg,
diag.lvl);
}
}
}
Ok(SharedEmitterMessage::InlineAsmError(cookie, msg)) => {
match ExpnId::from_u32(cookie).expn_info() {
Some(ei) => sess.span_err(ei.call_site, &msg),
None => sess.err(&msg),
}
}
Ok(SharedEmitterMessage::AbortIfErrors) => {
sess.abort_if_errors();
}
Ok(SharedEmitterMessage::Fatal(msg)) => {
sess.fatal(&msg);
}
Err(_) => {
break;
}
}
}
}
}
pub struct OngoingCodegen<B: ExtraBackendMethods> {
pub backend: B,
pub crate_name: Symbol,
pub crate_hash: Svh,
pub metadata: EncodedMetadata,
pub windows_subsystem: Option<String>,
pub linker_info: LinkerInfo,
pub crate_info: CrateInfo,
pub coordinator_send: Sender<Box<dyn Any + Send>>,
pub codegen_worker_receive: Receiver<Message<B>>,
pub shared_emitter_main: SharedEmitterMain,
pub future: thread::JoinHandle<Result<CompiledModules, ()>>,
pub output_filenames: Arc<OutputFilenames>,
}
impl<B: ExtraBackendMethods> OngoingCodegen<B> {
pub fn join(
self,
sess: &Session
) -> (CodegenResults, FxHashMap<WorkProductId, WorkProduct>) {
self.shared_emitter_main.check(sess, true);
let compiled_modules = match self.future.join() {
Ok(Ok(compiled_modules)) => compiled_modules,
Ok(Err(())) => {
sess.abort_if_errors();
panic!("expected abort due to worker thread errors")
},
Err(_) => {
bug!("panic during codegen/LLVM phase");
}
};
sess.cgu_reuse_tracker.check_expected_reuse(sess);
sess.abort_if_errors();
let work_products =
copy_all_cgu_workproducts_to_incr_comp_cache_dir(sess,
&compiled_modules);
produce_final_output_artifacts(sess,
&compiled_modules,
&self.output_filenames);
// FIXME: time_llvm_passes support - does this use a global context or
// something?
if sess.codegen_units() == 1 && sess.time_llvm_passes() {
self.backend.print_pass_timings()
}
(CodegenResults {
crate_name: self.crate_name,
crate_hash: self.crate_hash,
metadata: self.metadata,
windows_subsystem: self.windows_subsystem,
linker_info: self.linker_info,
crate_info: self.crate_info,
modules: compiled_modules.modules,
allocator_module: compiled_modules.allocator_module,
metadata_module: compiled_modules.metadata_module,
}, work_products)
}
pub fn submit_pre_codegened_module_to_llvm(
&self,
tcx: TyCtxt<'_>,
module: ModuleCodegen<B::Module>,
) {
self.wait_for_signal_to_codegen_item();
self.check_for_errors(tcx.sess);
// These are generally cheap and won't throw off scheduling.
let cost = 0;
submit_codegened_module_to_llvm(&self.backend, tcx, module, cost);
}
pub fn codegen_finished(&self, tcx: TyCtxt<'_>) {
self.wait_for_signal_to_codegen_item();
self.check_for_errors(tcx.sess);
drop(self.coordinator_send.send(Box::new(Message::CodegenComplete::<B>)));
}
/// Consumes this context indicating that codegen was entirely aborted, and
/// we need to exit as quickly as possible.
///
/// This method blocks the current thread until all worker threads have
/// finished, and all worker threads should have exited or be real close to
/// exiting at this point.
pub fn codegen_aborted(self) {
// Signal to the coordinator it should spawn no more work and start
// shutdown.
drop(self.coordinator_send.send(Box::new(Message::CodegenAborted::<B>)));
drop(self.future.join());
}
pub fn check_for_errors(&self, sess: &Session) {
self.shared_emitter_main.check(sess, false);
}
pub fn wait_for_signal_to_codegen_item(&self) {
match self.codegen_worker_receive.recv() {
Ok(Message::CodegenItem) => {
// Nothing to do
}
Ok(_) => panic!("unexpected message"),
Err(_) => {
// One of the LLVM threads must have panicked, fall through so
// error handling can be reached.
}
}
}
}
pub fn submit_codegened_module_to_llvm<B: ExtraBackendMethods>(
_backend: &B,
tcx: TyCtxt<'_>,
module: ModuleCodegen<B::Module>,
cost: u64,
) {
let llvm_work_item = WorkItem::Optimize(module);
drop(tcx.tx_to_llvm_workers.lock().send(Box::new(Message::CodegenDone::<B> {
llvm_work_item,
cost,
})));
}
pub fn submit_post_lto_module_to_llvm<B: ExtraBackendMethods>(
_backend: &B,
tcx: TyCtxt<'_>,
module: CachedModuleCodegen,
) {
let llvm_work_item = WorkItem::CopyPostLtoArtifacts(module);
drop(tcx.tx_to_llvm_workers.lock().send(Box::new(Message::CodegenDone::<B> {
llvm_work_item,
cost: 0,
})));
}
pub fn submit_pre_lto_module_to_llvm<B: ExtraBackendMethods>(
_backend: &B,
tcx: TyCtxt<'_>,
module: CachedModuleCodegen,
) {
let filename = pre_lto_bitcode_filename(&module.name);
let bc_path = in_incr_comp_dir_sess(tcx.sess, &filename);
let file = fs::File::open(&bc_path).unwrap_or_else(|e| {
panic!("failed to open bitcode file `{}`: {}", bc_path.display(), e)
});
let mmap = unsafe {
memmap::Mmap::map(&file).unwrap_or_else(|e| {
panic!("failed to mmap bitcode file `{}`: {}", bc_path.display(), e)
})
};
// Schedule the module to be loaded
drop(tcx.tx_to_llvm_workers.lock().send(Box::new(Message::AddImportOnlyModule::<B> {
module_data: SerializedModule::FromUncompressedFile(mmap),
work_product: module.source,
})));
}
pub fn pre_lto_bitcode_filename(module_name: &str) -> String {
format!("{}.{}", module_name, PRE_LTO_BC_EXT)
}
fn msvc_imps_needed(tcx: TyCtxt<'_>) -> bool {
// This should never be true (because it's not supported). If it is true,
// something is wrong with commandline arg validation.
assert!(!(tcx.sess.opts.cg.linker_plugin_lto.enabled() &&
tcx.sess.target.target.options.is_like_msvc &&
tcx.sess.opts.cg.prefer_dynamic));
tcx.sess.target.target.options.is_like_msvc &&
tcx.sess.crate_types.borrow().iter().any(|ct| *ct == config::CrateType::Rlib) &&
// ThinLTO can't handle this workaround in all cases, so we don't
// emit the `__imp_` symbols. Instead we make them unnecessary by disallowing
// dynamic linking when linker plugin LTO is enabled.
!tcx.sess.opts.cg.linker_plugin_lto.enabled()
}
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