1 use crate::back::write::{
2 compute_per_cgu_lto_type, start_async_codegen, submit_codegened_module_to_llvm,
3 submit_post_lto_module_to_llvm, submit_pre_lto_module_to_llvm, ComputedLtoType, OngoingCodegen,
5 use crate::common::{IntPredicate, RealPredicate, TypeKind};
8 use crate::mir::operand::OperandValue;
9 use crate::mir::place::PlaceRef;
11 use crate::{CachedModuleCodegen, CrateInfo, MemFlags, ModuleCodegen, ModuleKind};
13 use rustc_attr as attr;
14 use rustc_data_structures::fx::FxHashMap;
15 use rustc_data_structures::profiling::{get_resident_set_size, print_time_passes_entry};
16 use rustc_data_structures::sync::{par_iter, ParallelIterator};
18 use rustc_hir::def_id::{LocalDefId, LOCAL_CRATE};
19 use rustc_hir::lang_items::LangItem;
20 use rustc_index::vec::Idx;
21 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
22 use rustc_middle::middle::cstore::EncodedMetadata;
23 use rustc_middle::middle::cstore::{self, LinkagePreference};
24 use rustc_middle::middle::lang_items;
25 use rustc_middle::mir::mono::{CodegenUnit, CodegenUnitNameBuilder, MonoItem};
26 use rustc_middle::ty::layout::{HasTyCtxt, TyAndLayout};
27 use rustc_middle::ty::layout::{FAT_PTR_ADDR, FAT_PTR_EXTRA};
28 use rustc_middle::ty::query::Providers;
29 use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
30 use rustc_session::cgu_reuse_tracker::CguReuse;
31 use rustc_session::config::{self, EntryFnType};
32 use rustc_session::Session;
33 use rustc_target::abi::{Align, LayoutOf, VariantIdx};
35 use std::ops::{Deref, DerefMut};
36 use std::time::{Duration, Instant};
38 use itertools::Itertools;
40 pub fn bin_op_to_icmp_predicate(op: hir::BinOpKind, signed: bool) -> IntPredicate {
42 hir::BinOpKind::Eq => IntPredicate::IntEQ,
43 hir::BinOpKind::Ne => IntPredicate::IntNE,
44 hir::BinOpKind::Lt => {
51 hir::BinOpKind::Le => {
58 hir::BinOpKind::Gt => {
65 hir::BinOpKind::Ge => {
73 "comparison_op_to_icmp_predicate: expected comparison operator, \
80 pub fn bin_op_to_fcmp_predicate(op: hir::BinOpKind) -> RealPredicate {
82 hir::BinOpKind::Eq => RealPredicate::RealOEQ,
83 hir::BinOpKind::Ne => RealPredicate::RealUNE,
84 hir::BinOpKind::Lt => RealPredicate::RealOLT,
85 hir::BinOpKind::Le => RealPredicate::RealOLE,
86 hir::BinOpKind::Gt => RealPredicate::RealOGT,
87 hir::BinOpKind::Ge => RealPredicate::RealOGE,
90 "comparison_op_to_fcmp_predicate: expected comparison operator, \
98 pub fn compare_simd_types<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
106 let signed = match t.kind() {
108 let cmp = bin_op_to_fcmp_predicate(op);
109 let cmp = bx.fcmp(cmp, lhs, rhs);
110 return bx.sext(cmp, ret_ty);
112 ty::Uint(_) => false,
114 _ => bug!("compare_simd_types: invalid SIMD type"),
117 let cmp = bin_op_to_icmp_predicate(op, signed);
118 let cmp = bx.icmp(cmp, lhs, rhs);
119 // LLVM outputs an `< size x i1 >`, so we need to perform a sign extension
120 // to get the correctly sized type. This will compile to a single instruction
121 // once the IR is converted to assembly if the SIMD instruction is supported
122 // by the target architecture.
126 /// Retrieves the information we are losing (making dynamic) in an unsizing
129 /// The `old_info` argument is a bit odd. It is intended for use in an upcast,
130 /// where the new vtable for an object will be derived from the old one.
131 pub fn unsized_info<'tcx, Cx: CodegenMethods<'tcx>>(
135 old_info: Option<Cx::Value>,
137 let (source, target) =
138 cx.tcx().struct_lockstep_tails_erasing_lifetimes(source, target, cx.param_env());
139 match (source.kind(), target.kind()) {
140 (&ty::Array(_, len), &ty::Slice(_)) => {
141 cx.const_usize(len.eval_usize(cx.tcx(), ty::ParamEnv::reveal_all()))
143 (&ty::Dynamic(..), &ty::Dynamic(..)) => {
144 // For now, upcasts are limited to changes in marker
145 // traits, and hence never actually require an actual
146 // change to the vtable.
147 old_info.expect("unsized_info: missing old info for trait upcast")
149 (_, &ty::Dynamic(ref data, ..)) => {
150 let vtable_ptr = cx.layout_of(cx.tcx().mk_mut_ptr(target)).field(cx, FAT_PTR_EXTRA);
152 meth::get_vtable(cx, source, data.principal()),
153 cx.backend_type(vtable_ptr),
156 _ => bug!("unsized_info: invalid unsizing {:?} -> {:?}", source, target),
160 /// Coerces `src` to `dst_ty`. `src_ty` must be a thin pointer.
161 pub fn unsize_thin_ptr<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
166 ) -> (Bx::Value, Bx::Value) {
167 debug!("unsize_thin_ptr: {:?} => {:?}", src_ty, dst_ty);
168 match (src_ty.kind(), dst_ty.kind()) {
169 (&ty::Ref(_, a, _), &ty::Ref(_, b, _) | &ty::RawPtr(ty::TypeAndMut { ty: b, .. }))
170 | (&ty::RawPtr(ty::TypeAndMut { ty: a, .. }), &ty::RawPtr(ty::TypeAndMut { ty: b, .. })) => {
171 assert!(bx.cx().type_is_sized(a));
172 let ptr_ty = bx.cx().type_ptr_to(bx.cx().backend_type(bx.cx().layout_of(b)));
173 (bx.pointercast(src, ptr_ty), unsized_info(bx.cx(), a, b, None))
175 (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => {
176 assert_eq!(def_a, def_b);
178 let src_layout = bx.cx().layout_of(src_ty);
179 let dst_layout = bx.cx().layout_of(dst_ty);
180 let mut result = None;
181 for i in 0..src_layout.fields.count() {
182 let src_f = src_layout.field(bx.cx(), i);
183 assert_eq!(src_layout.fields.offset(i).bytes(), 0);
184 assert_eq!(dst_layout.fields.offset(i).bytes(), 0);
188 assert_eq!(src_layout.size, src_f.size);
190 let dst_f = dst_layout.field(bx.cx(), i);
191 assert_ne!(src_f.ty, dst_f.ty);
192 assert_eq!(result, None);
193 result = Some(unsize_thin_ptr(bx, src, src_f.ty, dst_f.ty));
195 let (lldata, llextra) = result.unwrap();
196 // HACK(eddyb) have to bitcast pointers until LLVM removes pointee types.
197 // FIXME(eddyb) move these out of this `match` arm, so they're always
198 // applied, uniformly, no matter the source/destination types.
200 bx.bitcast(lldata, bx.cx().scalar_pair_element_backend_type(dst_layout, 0, true)),
201 bx.bitcast(llextra, bx.cx().scalar_pair_element_backend_type(dst_layout, 1, true)),
204 _ => bug!("unsize_thin_ptr: called on bad types"),
208 /// Coerces `src`, which is a reference to a value of type `src_ty`,
209 /// to a value of type `dst_ty`, and stores the result in `dst`.
210 pub fn coerce_unsized_into<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
212 src: PlaceRef<'tcx, Bx::Value>,
213 dst: PlaceRef<'tcx, Bx::Value>,
215 let src_ty = src.layout.ty;
216 let dst_ty = dst.layout.ty;
217 match (src_ty.kind(), dst_ty.kind()) {
218 (&ty::Ref(..), &ty::Ref(..) | &ty::RawPtr(..)) | (&ty::RawPtr(..), &ty::RawPtr(..)) => {
219 let (base, info) = match bx.load_operand(src).val {
220 OperandValue::Pair(base, info) => {
221 // fat-ptr to fat-ptr unsize preserves the vtable
222 // i.e., &'a fmt::Debug+Send => &'a fmt::Debug
223 // So we need to pointercast the base to ensure
224 // the types match up.
225 // FIXME(eddyb) use `scalar_pair_element_backend_type` here,
226 // like `unsize_thin_ptr` does.
227 let thin_ptr = dst.layout.field(bx.cx(), FAT_PTR_ADDR);
228 (bx.pointercast(base, bx.cx().backend_type(thin_ptr)), info)
230 OperandValue::Immediate(base) => unsize_thin_ptr(bx, base, src_ty, dst_ty),
231 OperandValue::Ref(..) => bug!(),
233 OperandValue::Pair(base, info).store(bx, dst);
236 (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => {
237 assert_eq!(def_a, def_b);
239 for i in 0..def_a.variants[VariantIdx::new(0)].fields.len() {
240 let src_f = src.project_field(bx, i);
241 let dst_f = dst.project_field(bx, i);
243 if dst_f.layout.is_zst() {
247 if src_f.layout.ty == dst_f.layout.ty {
258 coerce_unsized_into(bx, src_f, dst_f);
262 _ => bug!("coerce_unsized_into: invalid coercion {:?} -> {:?}", src_ty, dst_ty,),
266 pub fn cast_shift_expr_rhs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
272 cast_shift_rhs(bx, op, lhs, rhs)
275 fn cast_shift_rhs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
281 // Shifts may have any size int on the rhs
283 let mut rhs_llty = bx.cx().val_ty(rhs);
284 let mut lhs_llty = bx.cx().val_ty(lhs);
285 if bx.cx().type_kind(rhs_llty) == TypeKind::Vector {
286 rhs_llty = bx.cx().element_type(rhs_llty)
288 if bx.cx().type_kind(lhs_llty) == TypeKind::Vector {
289 lhs_llty = bx.cx().element_type(lhs_llty)
291 let rhs_sz = bx.cx().int_width(rhs_llty);
292 let lhs_sz = bx.cx().int_width(lhs_llty);
294 bx.trunc(rhs, lhs_llty)
295 } else if lhs_sz > rhs_sz {
296 // FIXME (#1877: If in the future shifting by negative
297 // values is no longer undefined then this is wrong.
298 bx.zext(rhs, lhs_llty)
307 /// Returns `true` if this session's target will use SEH-based unwinding.
309 /// This is only true for MSVC targets, and even then the 64-bit MSVC target
310 /// currently uses SEH-ish unwinding with DWARF info tables to the side (same as
311 /// 64-bit MinGW) instead of "full SEH".
312 pub fn wants_msvc_seh(sess: &Session) -> bool {
313 sess.target.is_like_msvc
316 pub fn memcpy_ty<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
322 layout: TyAndLayout<'tcx>,
325 let size = layout.size.bytes();
330 bx.memcpy(dst, dst_align, src, src_align, bx.cx().const_usize(size), flags);
333 pub fn codegen_instance<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>(
334 cx: &'a Bx::CodegenCx,
335 instance: Instance<'tcx>,
337 // this is an info! to allow collecting monomorphization statistics
338 // and to allow finding the last function before LLVM aborts from
340 info!("codegen_instance({})", instance);
342 mir::codegen_mir::<Bx>(cx, instance);
345 /// Creates the `main` function which will initialize the rust runtime and call
346 /// users main function.
347 pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
348 cx: &'a Bx::CodegenCx,
349 ) -> Option<Bx::Function> {
350 let main_def_id = cx.tcx().entry_fn(LOCAL_CRATE).map(|(def_id, _)| def_id)?;
351 let instance = Instance::mono(cx.tcx(), main_def_id.to_def_id());
353 if !cx.codegen_unit().contains_item(&MonoItem::Fn(instance)) {
354 // We want to create the wrapper in the same codegen unit as Rust's main
359 let main_llfn = cx.get_fn_addr(instance);
361 return cx.tcx().entry_fn(LOCAL_CRATE).map(|(_, et)| {
362 let use_start_lang_item = EntryFnType::Start != et;
363 create_entry_fn::<Bx>(cx, main_llfn, main_def_id, use_start_lang_item)
366 fn create_entry_fn<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
367 cx: &'a Bx::CodegenCx,
368 rust_main: Bx::Value,
369 rust_main_def_id: LocalDefId,
370 use_start_lang_item: bool,
372 // The entry function is either `int main(void)` or `int main(int argc, char **argv)`,
373 // depending on whether the target needs `argc` and `argv` to be passed in.
374 let llfty = if cx.sess().target.main_needs_argc_argv {
375 cx.type_func(&[cx.type_int(), cx.type_ptr_to(cx.type_i8p())], cx.type_int())
377 cx.type_func(&[], cx.type_int())
380 let main_ret_ty = cx.tcx().fn_sig(rust_main_def_id).output();
381 // Given that `main()` has no arguments,
382 // then its return type cannot have
383 // late-bound regions, since late-bound
384 // regions must appear in the argument
386 let main_ret_ty = cx.tcx().erase_regions(main_ret_ty.no_bound_vars().unwrap());
388 let llfn = match cx.declare_c_main(llfty) {
391 // FIXME: We should be smart and show a better diagnostic here.
392 let span = cx.tcx().def_span(rust_main_def_id);
394 .struct_span_err(span, "entry symbol `main` declared multiple times")
395 .help("did you use `#[no_mangle]` on `fn main`? Use `#[start]` instead")
397 cx.sess().abort_if_errors();
402 // `main` should respect same config for frame pointer elimination as rest of code
403 cx.set_frame_pointer_elimination(llfn);
404 cx.apply_target_cpu_attr(llfn);
406 let mut bx = Bx::new_block(&cx, llfn, "top");
408 bx.insert_reference_to_gdb_debug_scripts_section_global();
410 let (arg_argc, arg_argv) = get_argc_argv(cx, &mut bx);
412 let (start_fn, args) = if use_start_lang_item {
413 let start_def_id = cx.tcx().require_lang_item(LangItem::Start, None);
414 let start_fn = cx.get_fn_addr(
415 ty::Instance::resolve(
417 ty::ParamEnv::reveal_all(),
419 cx.tcx().intern_substs(&[main_ret_ty.into()]),
426 vec![bx.pointercast(rust_main, cx.type_ptr_to(cx.type_i8p())), arg_argc, arg_argv],
429 debug!("using user-defined start fn");
430 (rust_main, vec![arg_argc, arg_argv])
433 let result = bx.call(start_fn, &args, None);
434 let cast = bx.intcast(result, cx.type_int(), true);
441 /// Obtain the `argc` and `argv` values to pass to the rust start function.
442 fn get_argc_argv<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
443 cx: &'a Bx::CodegenCx,
445 ) -> (Bx::Value, Bx::Value) {
446 if cx.sess().target.main_needs_argc_argv {
447 // Params from native `main()` used as args for rust start function
448 let param_argc = bx.get_param(0);
449 let param_argv = bx.get_param(1);
450 let arg_argc = bx.intcast(param_argc, cx.type_isize(), true);
451 let arg_argv = param_argv;
454 // The Rust start function doesn't need `argc` and `argv`, so just pass zeros.
455 let arg_argc = bx.const_int(cx.type_int(), 0);
456 let arg_argv = bx.const_null(cx.type_ptr_to(cx.type_i8p()));
461 pub fn codegen_crate<B: ExtraBackendMethods>(
464 metadata: EncodedMetadata,
465 need_metadata_module: bool,
466 ) -> OngoingCodegen<B> {
467 // Skip crate items and just output metadata in -Z no-codegen mode.
468 if tcx.sess.opts.debugging_opts.no_codegen || !tcx.sess.opts.output_types.should_codegen() {
469 let ongoing_codegen = start_async_codegen(backend, tcx, metadata, 1);
471 ongoing_codegen.codegen_finished(tcx);
473 ongoing_codegen.check_for_errors(tcx.sess);
475 return ongoing_codegen;
478 let cgu_name_builder = &mut CodegenUnitNameBuilder::new(tcx);
480 // Run the monomorphization collector and partition the collected items into
482 let codegen_units = tcx.collect_and_partition_mono_items(LOCAL_CRATE).1;
484 // Force all codegen_unit queries so they are already either red or green
485 // when compile_codegen_unit accesses them. We are not able to re-execute
486 // the codegen_unit query from just the DepNode, so an unknown color would
487 // lead to having to re-execute compile_codegen_unit, possibly
489 if tcx.dep_graph.is_fully_enabled() {
490 for cgu in codegen_units {
491 tcx.ensure().codegen_unit(cgu.name());
495 let ongoing_codegen = start_async_codegen(backend.clone(), tcx, metadata, codegen_units.len());
496 let ongoing_codegen = AbortCodegenOnDrop::<B>(Some(ongoing_codegen));
498 // Codegen an allocator shim, if necessary.
500 // If the crate doesn't have an `allocator_kind` set then there's definitely
501 // no shim to generate. Otherwise we also check our dependency graph for all
502 // our output crate types. If anything there looks like its a `Dynamic`
503 // linkage, then it's already got an allocator shim and we'll be using that
504 // one instead. If nothing exists then it's our job to generate the
506 let any_dynamic_crate = tcx.dependency_formats(LOCAL_CRATE).iter().any(|(_, list)| {
507 use rustc_middle::middle::dependency_format::Linkage;
508 list.iter().any(|&linkage| linkage == Linkage::Dynamic)
510 let allocator_module = if any_dynamic_crate {
512 } else if let Some(kind) = tcx.allocator_kind() {
514 cgu_name_builder.build_cgu_name(LOCAL_CRATE, &["crate"], Some("allocator")).to_string();
515 let mut modules = backend.new_metadata(tcx, &llmod_id);
516 tcx.sess.time("write_allocator_module", || {
517 backend.codegen_allocator(tcx, &mut modules, kind, tcx.lang_items().oom().is_some())
520 Some(ModuleCodegen { name: llmod_id, module_llvm: modules, kind: ModuleKind::Allocator })
525 if let Some(allocator_module) = allocator_module {
526 ongoing_codegen.submit_pre_codegened_module_to_llvm(tcx, allocator_module);
529 if need_metadata_module {
530 // Codegen the encoded metadata.
531 let metadata_cgu_name =
532 cgu_name_builder.build_cgu_name(LOCAL_CRATE, &["crate"], Some("metadata")).to_string();
533 let mut metadata_llvm_module = backend.new_metadata(tcx, &metadata_cgu_name);
534 tcx.sess.time("write_compressed_metadata", || {
535 backend.write_compressed_metadata(
537 &ongoing_codegen.metadata,
538 &mut metadata_llvm_module,
542 let metadata_module = ModuleCodegen {
543 name: metadata_cgu_name,
544 module_llvm: metadata_llvm_module,
545 kind: ModuleKind::Metadata,
547 ongoing_codegen.submit_pre_codegened_module_to_llvm(tcx, metadata_module);
550 // For better throughput during parallel processing by LLVM, we used to sort
551 // CGUs largest to smallest. This would lead to better thread utilization
552 // by, for example, preventing a large CGU from being processed last and
553 // having only one LLVM thread working while the rest remained idle.
555 // However, this strategy would lead to high memory usage, as it meant the
556 // LLVM-IR for all of the largest CGUs would be resident in memory at once.
558 // Instead, we can compromise by ordering CGUs such that the largest and
559 // smallest are first, second largest and smallest are next, etc. If there
560 // are large size variations, this can reduce memory usage significantly.
561 let codegen_units: Vec<_> = {
562 let mut sorted_cgus = codegen_units.iter().collect::<Vec<_>>();
563 sorted_cgus.sort_by_cached_key(|cgu| cgu.size_estimate());
565 let (first_half, second_half) = sorted_cgus.split_at(sorted_cgus.len() / 2);
566 second_half.iter().rev().interleave(first_half).copied().collect()
569 // The non-parallel compiler can only translate codegen units to LLVM IR
570 // on a single thread, leading to a staircase effect where the N LLVM
571 // threads have to wait on the single codegen threads to generate work
572 // for them. The parallel compiler does not have this restriction, so
573 // we can pre-load the LLVM queue in parallel before handing off
574 // coordination to the OnGoingCodegen scheduler.
576 // This likely is a temporary measure. Once we don't have to support the
577 // non-parallel compiler anymore, we can compile CGUs end-to-end in
578 // parallel and get rid of the complicated scheduling logic.
579 let pre_compile_cgus = |cgu_reuse: &[CguReuse]| {
580 if cfg!(parallel_compiler) {
581 tcx.sess.time("compile_first_CGU_batch", || {
582 // Try to find one CGU to compile per thread.
583 let cgus: Vec<_> = cgu_reuse
586 .filter(|&(_, reuse)| reuse == &CguReuse::No)
587 .take(tcx.sess.threads())
590 // Compile the found CGUs in parallel.
591 let start_time = Instant::now();
593 let pre_compiled_cgus = par_iter(cgus)
595 let module = backend.compile_codegen_unit(tcx, codegen_units[i].name());
600 (pre_compiled_cgus, start_time.elapsed())
603 (FxHashMap::default(), Duration::new(0, 0))
607 let mut cgu_reuse = Vec::new();
608 let mut pre_compiled_cgus: Option<FxHashMap<usize, _>> = None;
609 let mut total_codegen_time = Duration::new(0, 0);
610 let start_rss = tcx.sess.time_passes().then(|| get_resident_set_size());
612 for (i, cgu) in codegen_units.iter().enumerate() {
613 ongoing_codegen.wait_for_signal_to_codegen_item();
614 ongoing_codegen.check_for_errors(tcx.sess);
616 // Do some setup work in the first iteration
617 if pre_compiled_cgus.is_none() {
618 // Calculate the CGU reuse
619 cgu_reuse = tcx.sess.time("find_cgu_reuse", || {
620 codegen_units.iter().map(|cgu| determine_cgu_reuse(tcx, &cgu)).collect()
622 // Pre compile some CGUs
623 let (compiled_cgus, codegen_time) = pre_compile_cgus(&cgu_reuse);
624 pre_compiled_cgus = Some(compiled_cgus);
625 total_codegen_time += codegen_time;
628 let cgu_reuse = cgu_reuse[i];
629 tcx.sess.cgu_reuse_tracker.set_actual_reuse(&cgu.name().as_str(), cgu_reuse);
634 if let Some(cgu) = pre_compiled_cgus.as_mut().unwrap().remove(&i) {
637 let start_time = Instant::now();
638 let module = backend.compile_codegen_unit(tcx, cgu.name());
639 total_codegen_time += start_time.elapsed();
642 // This will unwind if there are errors, which triggers our `AbortCodegenOnDrop`
643 // guard. Unfortunately, just skipping the `submit_codegened_module_to_llvm` makes
644 // compilation hang on post-monomorphization errors.
645 tcx.sess.abort_if_errors();
647 submit_codegened_module_to_llvm(
649 &ongoing_codegen.coordinator_send,
655 CguReuse::PreLto => {
656 submit_pre_lto_module_to_llvm(
659 &ongoing_codegen.coordinator_send,
660 CachedModuleCodegen {
661 name: cgu.name().to_string(),
662 source: cgu.work_product(tcx),
667 CguReuse::PostLto => {
668 submit_post_lto_module_to_llvm(
670 &ongoing_codegen.coordinator_send,
671 CachedModuleCodegen {
672 name: cgu.name().to_string(),
673 source: cgu.work_product(tcx),
681 ongoing_codegen.codegen_finished(tcx);
683 // Since the main thread is sometimes blocked during codegen, we keep track
684 // -Ztime-passes output manually.
685 if tcx.sess.time_passes() {
686 let end_rss = get_resident_set_size();
688 print_time_passes_entry(
689 "codegen_to_LLVM_IR",
696 ongoing_codegen.check_for_errors(tcx.sess);
698 ongoing_codegen.into_inner()
701 /// A curious wrapper structure whose only purpose is to call `codegen_aborted`
702 /// when it's dropped abnormally.
704 /// In the process of working on rust-lang/rust#55238 a mysterious segfault was
705 /// stumbled upon. The segfault was never reproduced locally, but it was
706 /// suspected to be related to the fact that codegen worker threads were
707 /// sticking around by the time the main thread was exiting, causing issues.
709 /// This structure is an attempt to fix that issue where the `codegen_aborted`
710 /// message will block until all workers have finished. This should ensure that
711 /// even if the main codegen thread panics we'll wait for pending work to
712 /// complete before returning from the main thread, hopefully avoiding
715 /// If you see this comment in the code, then it means that this workaround
716 /// worked! We may yet one day track down the mysterious cause of that
718 struct AbortCodegenOnDrop<B: ExtraBackendMethods>(Option<OngoingCodegen<B>>);
720 impl<B: ExtraBackendMethods> AbortCodegenOnDrop<B> {
721 fn into_inner(mut self) -> OngoingCodegen<B> {
722 self.0.take().unwrap()
726 impl<B: ExtraBackendMethods> Deref for AbortCodegenOnDrop<B> {
727 type Target = OngoingCodegen<B>;
729 fn deref(&self) -> &OngoingCodegen<B> {
730 self.0.as_ref().unwrap()
734 impl<B: ExtraBackendMethods> DerefMut for AbortCodegenOnDrop<B> {
735 fn deref_mut(&mut self) -> &mut OngoingCodegen<B> {
736 self.0.as_mut().unwrap()
740 impl<B: ExtraBackendMethods> Drop for AbortCodegenOnDrop<B> {
742 if let Some(codegen) = self.0.take() {
743 codegen.codegen_aborted();
749 pub fn new(tcx: TyCtxt<'_>) -> CrateInfo {
750 let mut info = CrateInfo {
752 compiler_builtins: None,
753 profiler_runtime: None,
754 is_no_builtins: Default::default(),
755 native_libraries: Default::default(),
756 used_libraries: tcx.native_libraries(LOCAL_CRATE).iter().map(Into::into).collect(),
757 link_args: tcx.link_args(LOCAL_CRATE),
758 crate_name: Default::default(),
759 used_crates_dynamic: cstore::used_crates(tcx, LinkagePreference::RequireDynamic),
760 used_crates_static: cstore::used_crates(tcx, LinkagePreference::RequireStatic),
761 used_crate_source: Default::default(),
762 lang_item_to_crate: Default::default(),
763 missing_lang_items: Default::default(),
764 dependency_formats: tcx.dependency_formats(LOCAL_CRATE),
766 let lang_items = tcx.lang_items();
768 let crates = tcx.crates();
770 let n_crates = crates.len();
771 info.native_libraries.reserve(n_crates);
772 info.crate_name.reserve(n_crates);
773 info.used_crate_source.reserve(n_crates);
774 info.missing_lang_items.reserve(n_crates);
776 for &cnum in crates.iter() {
777 info.native_libraries
778 .insert(cnum, tcx.native_libraries(cnum).iter().map(Into::into).collect());
779 info.crate_name.insert(cnum, tcx.crate_name(cnum).to_string());
780 info.used_crate_source.insert(cnum, tcx.used_crate_source(cnum));
781 if tcx.is_panic_runtime(cnum) {
782 info.panic_runtime = Some(cnum);
784 if tcx.is_compiler_builtins(cnum) {
785 info.compiler_builtins = Some(cnum);
787 if tcx.is_profiler_runtime(cnum) {
788 info.profiler_runtime = Some(cnum);
790 if tcx.is_no_builtins(cnum) {
791 info.is_no_builtins.insert(cnum);
793 let missing = tcx.missing_lang_items(cnum);
794 for &item in missing.iter() {
795 if let Ok(id) = lang_items.require(item) {
796 info.lang_item_to_crate.insert(item, id.krate);
800 // No need to look for lang items that don't actually need to exist.
802 missing.iter().cloned().filter(|&l| lang_items::required(tcx, l)).collect();
803 info.missing_lang_items.insert(cnum, missing);
810 pub fn provide(providers: &mut Providers) {
811 providers.backend_optimization_level = |tcx, cratenum| {
812 let for_speed = match tcx.sess.opts.optimize {
813 // If globally no optimisation is done, #[optimize] has no effect.
815 // This is done because if we ended up "upgrading" to `-O2` here, we’d populate the
816 // pass manager and it is likely that some module-wide passes (such as inliner or
817 // cross-function constant propagation) would ignore the `optnone` annotation we put
818 // on the functions, thus necessarily involving these functions into optimisations.
819 config::OptLevel::No => return config::OptLevel::No,
820 // If globally optimise-speed is already specified, just use that level.
821 config::OptLevel::Less => return config::OptLevel::Less,
822 config::OptLevel::Default => return config::OptLevel::Default,
823 config::OptLevel::Aggressive => return config::OptLevel::Aggressive,
824 // If globally optimize-for-size has been requested, use -O2 instead (if optimize(size)
826 config::OptLevel::Size => config::OptLevel::Default,
827 config::OptLevel::SizeMin => config::OptLevel::Default,
830 let (defids, _) = tcx.collect_and_partition_mono_items(cratenum);
832 let CodegenFnAttrs { optimize, .. } = tcx.codegen_fn_attrs(*id);
834 attr::OptimizeAttr::None => continue,
835 attr::OptimizeAttr::Size => continue,
836 attr::OptimizeAttr::Speed => {
841 tcx.sess.opts.optimize
845 fn determine_cgu_reuse<'tcx>(tcx: TyCtxt<'tcx>, cgu: &CodegenUnit<'tcx>) -> CguReuse {
846 if !tcx.dep_graph.is_fully_enabled() {
850 let work_product_id = &cgu.work_product_id();
851 if tcx.dep_graph.previous_work_product(work_product_id).is_none() {
852 // We don't have anything cached for this CGU. This can happen
853 // if the CGU did not exist in the previous session.
857 // Try to mark the CGU as green. If it we can do so, it means that nothing
858 // affecting the LLVM module has changed and we can re-use a cached version.
859 // If we compile with any kind of LTO, this means we can re-use the bitcode
860 // of the Pre-LTO stage (possibly also the Post-LTO version but we'll only
861 // know that later). If we are not doing LTO, there is only one optimized
862 // version of each module, so we re-use that.
863 let dep_node = cgu.codegen_dep_node(tcx);
865 !tcx.dep_graph.dep_node_exists(&dep_node),
866 "CompileCodegenUnit dep-node for CGU `{}` already exists before marking.",
870 if tcx.try_mark_green(&dep_node) {
871 // We can re-use either the pre- or the post-thinlto state. If no LTO is
872 // being performed then we can use post-LTO artifacts, otherwise we must
873 // reuse pre-LTO artifacts
874 match compute_per_cgu_lto_type(
877 &tcx.sess.crate_types(),
880 ComputedLtoType::No => CguReuse::PostLto,
881 _ => CguReuse::PreLto,