compiler/rustc_codegen_ssa/src/base.rs

   1 //! Codegen the completed AST to the LLVM IR.
   2 //!
   3 //! Some functions here, such as `codegen_block` and `codegen_expr`, return a value --
   4 //! the result of the codegen to LLVM -- while others, such as `codegen_fn`
   5 //! and `mono_item`, are called only for the side effect of adding a
   6 //! particular definition to the LLVM IR output we're producing.
   7 //!
   8 //! Hopefully useful general knowledge about codegen:
   9 //!
  10 //! * There's no way to find out the `Ty` type of a `Value`. Doing so
  11 //!   would be "trying to get the eggs out of an omelette" (credit:
  12 //!   pcwalton). You can, instead, find out its `llvm::Type` by calling `val_ty`,
  13 //!   but one `llvm::Type` corresponds to many `Ty`s; for instance, `tup(int, int,
  14 //!   int)` and `rec(x=int, y=int, z=int)` will have the same `llvm::Type`.
  15
  16 use crate::back::write::{
  17     compute_per_cgu_lto_type, start_async_codegen, submit_codegened_module_to_llvm,
  18     submit_post_lto_module_to_llvm, submit_pre_lto_module_to_llvm, ComputedLtoType, OngoingCodegen,
  19 };
  20 use crate::common::{IntPredicate, RealPredicate, TypeKind};
  21 use crate::meth;
  22 use crate::mir;
  23 use crate::mir::operand::OperandValue;
  24 use crate::mir::place::PlaceRef;
  25 use crate::traits::*;
  26 use crate::{CachedModuleCodegen, CrateInfo, MemFlags, ModuleCodegen, ModuleKind};
  27
  28 use rustc_attr as attr;
  29 use rustc_data_structures::fx::FxHashMap;
  30 use rustc_data_structures::profiling::print_time_passes_entry;
  31 use rustc_data_structures::sync::{par_iter, Lock, ParallelIterator};
  32 use rustc_hir as hir;
  33 use rustc_hir::def_id::{LocalDefId, LOCAL_CRATE};
  34 use rustc_hir::lang_items::LangItem;
  35 use rustc_index::vec::Idx;
  36 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
  37 use rustc_middle::middle::cstore::EncodedMetadata;
  38 use rustc_middle::middle::cstore::{self, LinkagePreference};
  39 use rustc_middle::middle::lang_items;
  40 use rustc_middle::mir::mono::{CodegenUnit, CodegenUnitNameBuilder, MonoItem};
  41 use rustc_middle::ty::layout::{HasTyCtxt, TyAndLayout};
  42 use rustc_middle::ty::layout::{FAT_PTR_ADDR, FAT_PTR_EXTRA};
  43 use rustc_middle::ty::query::Providers;
  44 use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
  45 use rustc_session::cgu_reuse_tracker::CguReuse;
  46 use rustc_session::config::{self, EntryFnType};
  47 use rustc_session::utils::NativeLibKind;
  48 use rustc_session::Session;
  49 use rustc_symbol_mangling::test as symbol_names_test;
  50 use rustc_target::abi::{Align, LayoutOf, VariantIdx};
  51
  52 use std::cmp;
  53 use std::ops::{Deref, DerefMut};
  54 use std::time::{Duration, Instant};
  55
  56 pub fn bin_op_to_icmp_predicate(op: hir::BinOpKind, signed: bool) -> IntPredicate {
  57     match op {
  58         hir::BinOpKind::Eq => IntPredicate::IntEQ,
  59         hir::BinOpKind::Ne => IntPredicate::IntNE,
  60         hir::BinOpKind::Lt => {
  61             if signed {
  62                 IntPredicate::IntSLT
  63             } else {
  64                 IntPredicate::IntULT
  65             }
  66         }
  67         hir::BinOpKind::Le => {
  68             if signed {
  69                 IntPredicate::IntSLE
  70             } else {
  71                 IntPredicate::IntULE
  72             }
  73         }
  74         hir::BinOpKind::Gt => {
  75             if signed {
  76                 IntPredicate::IntSGT
  77             } else {
  78                 IntPredicate::IntUGT
  79             }
  80         }
  81         hir::BinOpKind::Ge => {
  82             if signed {
  83                 IntPredicate::IntSGE
  84             } else {
  85                 IntPredicate::IntUGE
  86             }
  87         }
  88         op => bug!(
  89             "comparison_op_to_icmp_predicate: expected comparison operator, \
  90              found {:?}",
  91             op
  92         ),
  93     }
  94 }
  95
  96 pub fn bin_op_to_fcmp_predicate(op: hir::BinOpKind) -> RealPredicate {
  97     match op {
  98         hir::BinOpKind::Eq => RealPredicate::RealOEQ,
  99         hir::BinOpKind::Ne => RealPredicate::RealUNE,
 100         hir::BinOpKind::Lt => RealPredicate::RealOLT,
 101         hir::BinOpKind::Le => RealPredicate::RealOLE,
 102         hir::BinOpKind::Gt => RealPredicate::RealOGT,
 103         hir::BinOpKind::Ge => RealPredicate::RealOGE,
 104         op => {
 105             bug!(
 106                 "comparison_op_to_fcmp_predicate: expected comparison operator, \
 107                  found {:?}",
 108                 op
 109             );
 110         }
 111     }
 112 }
 113
 114 pub fn compare_simd_types<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 115     bx: &mut Bx,
 116     lhs: Bx::Value,
 117     rhs: Bx::Value,
 118     t: Ty<'tcx>,
 119     ret_ty: Bx::Type,
 120     op: hir::BinOpKind,
 121 ) -> Bx::Value {
 122     let signed = match t.kind() {
 123         ty::Float(_) => {
 124             let cmp = bin_op_to_fcmp_predicate(op);
 125             let cmp = bx.fcmp(cmp, lhs, rhs);
 126             return bx.sext(cmp, ret_ty);
 127         }
 128         ty::Uint(_) => false,
 129         ty::Int(_) => true,
 130         _ => bug!("compare_simd_types: invalid SIMD type"),
 131     };
 132
 133     let cmp = bin_op_to_icmp_predicate(op, signed);
 134     let cmp = bx.icmp(cmp, lhs, rhs);
 135     // LLVM outputs an `< size x i1 >`, so we need to perform a sign extension
 136     // to get the correctly sized type. This will compile to a single instruction
 137     // once the IR is converted to assembly if the SIMD instruction is supported
 138     // by the target architecture.
 139     bx.sext(cmp, ret_ty)
 140 }
 141
 142 /// Retrieves the information we are losing (making dynamic) in an unsizing
 143 /// adjustment.
 144 ///
 145 /// The `old_info` argument is a bit odd. It is intended for use in an upcast,
 146 /// where the new vtable for an object will be derived from the old one.
 147 pub fn unsized_info<'tcx, Cx: CodegenMethods<'tcx>>(
 148     cx: &Cx,
 149     source: Ty<'tcx>,
 150     target: Ty<'tcx>,
 151     old_info: Option<Cx::Value>,
 152 ) -> Cx::Value {
 153     let (source, target) =
 154         cx.tcx().struct_lockstep_tails_erasing_lifetimes(source, target, cx.param_env());
 155     match (source.kind(), target.kind()) {
 156         (&ty::Array(_, len), &ty::Slice(_)) => {
 157             cx.const_usize(len.eval_usize(cx.tcx(), ty::ParamEnv::reveal_all()))
 158         }
 159         (&ty::Dynamic(..), &ty::Dynamic(..)) => {
 160             // For now, upcasts are limited to changes in marker
 161             // traits, and hence never actually require an actual
 162             // change to the vtable.
 163             old_info.expect("unsized_info: missing old info for trait upcast")
 164         }
 165         (_, &ty::Dynamic(ref data, ..)) => {
 166             let vtable_ptr = cx.layout_of(cx.tcx().mk_mut_ptr(target)).field(cx, FAT_PTR_EXTRA);
 167             cx.const_ptrcast(
 168                 meth::get_vtable(cx, source, data.principal()),
 169                 cx.backend_type(vtable_ptr),
 170             )
 171         }
 172         _ => bug!("unsized_info: invalid unsizing {:?} -> {:?}", source, target),
 173     }
 174 }
 175
 176 /// Coerces `src` to `dst_ty`. `src_ty` must be a thin pointer.
 177 pub fn unsize_thin_ptr<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 178     bx: &mut Bx,
 179     src: Bx::Value,
 180     src_ty: Ty<'tcx>,
 181     dst_ty: Ty<'tcx>,
 182 ) -> (Bx::Value, Bx::Value) {
 183     debug!("unsize_thin_ptr: {:?} => {:?}", src_ty, dst_ty);
 184     match (src_ty.kind(), dst_ty.kind()) {
 185         (&ty::Ref(_, a, _), &ty::Ref(_, b, _) | &ty::RawPtr(ty::TypeAndMut { ty: b, .. }))
 186         | (&ty::RawPtr(ty::TypeAndMut { ty: a, .. }), &ty::RawPtr(ty::TypeAndMut { ty: b, .. })) => {
 187             assert!(bx.cx().type_is_sized(a));
 188             let ptr_ty = bx.cx().type_ptr_to(bx.cx().backend_type(bx.cx().layout_of(b)));
 189             (bx.pointercast(src, ptr_ty), unsized_info(bx.cx(), a, b, None))
 190         }
 191         (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => {
 192             assert_eq!(def_a, def_b);
 193
 194             let src_layout = bx.cx().layout_of(src_ty);
 195             let dst_layout = bx.cx().layout_of(dst_ty);
 196             let mut result = None;
 197             for i in 0..src_layout.fields.count() {
 198                 let src_f = src_layout.field(bx.cx(), i);
 199                 assert_eq!(src_layout.fields.offset(i).bytes(), 0);
 200                 assert_eq!(dst_layout.fields.offset(i).bytes(), 0);
 201                 if src_f.is_zst() {
 202                     continue;
 203                 }
 204                 assert_eq!(src_layout.size, src_f.size);
 205
 206                 let dst_f = dst_layout.field(bx.cx(), i);
 207                 assert_ne!(src_f.ty, dst_f.ty);
 208                 assert_eq!(result, None);
 209                 result = Some(unsize_thin_ptr(bx, src, src_f.ty, dst_f.ty));
 210             }
 211             let (lldata, llextra) = result.unwrap();
 212             // HACK(eddyb) have to bitcast pointers until LLVM removes pointee types.
 213             // FIXME(eddyb) move these out of this `match` arm, so they're always
 214             // applied, uniformly, no matter the source/destination types.
 215             (
 216                 bx.bitcast(lldata, bx.cx().scalar_pair_element_backend_type(dst_layout, 0, true)),
 217                 bx.bitcast(llextra, bx.cx().scalar_pair_element_backend_type(dst_layout, 1, true)),
 218             )
 219         }
 220         _ => bug!("unsize_thin_ptr: called on bad types"),
 221     }
 222 }
 223
 224 /// Coerces `src`, which is a reference to a value of type `src_ty`,
 225 /// to a value of type `dst_ty`, and stores the result in `dst`.
 226 pub fn coerce_unsized_into<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 227     bx: &mut Bx,
 228     src: PlaceRef<'tcx, Bx::Value>,
 229     dst: PlaceRef<'tcx, Bx::Value>,
 230 ) {
 231     let src_ty = src.layout.ty;
 232     let dst_ty = dst.layout.ty;
 233     match (src_ty.kind(), dst_ty.kind()) {
 234         (&ty::Ref(..), &ty::Ref(..) | &ty::RawPtr(..)) | (&ty::RawPtr(..), &ty::RawPtr(..)) => {
 235             let (base, info) = match bx.load_operand(src).val {
 236                 OperandValue::Pair(base, info) => {
 237                     // fat-ptr to fat-ptr unsize preserves the vtable
 238                     // i.e., &'a fmt::Debug+Send => &'a fmt::Debug
 239                     // So we need to pointercast the base to ensure
 240                     // the types match up.
 241                     // FIXME(eddyb) use `scalar_pair_element_backend_type` here,
 242                     // like `unsize_thin_ptr` does.
 243                     let thin_ptr = dst.layout.field(bx.cx(), FAT_PTR_ADDR);
 244                     (bx.pointercast(base, bx.cx().backend_type(thin_ptr)), info)
 245                 }
 246                 OperandValue::Immediate(base) => unsize_thin_ptr(bx, base, src_ty, dst_ty),
 247                 OperandValue::Ref(..) => bug!(),
 248             };
 249             OperandValue::Pair(base, info).store(bx, dst);
 250         }
 251
 252         (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => {
 253             assert_eq!(def_a, def_b);
 254
 255             for i in 0..def_a.variants[VariantIdx::new(0)].fields.len() {
 256                 let src_f = src.project_field(bx, i);
 257                 let dst_f = dst.project_field(bx, i);
 258
 259                 if dst_f.layout.is_zst() {
 260                     continue;
 261                 }
 262
 263                 if src_f.layout.ty == dst_f.layout.ty {
 264                     memcpy_ty(
 265                         bx,
 266                         dst_f.llval,
 267                         dst_f.align,
 268                         src_f.llval,
 269                         src_f.align,
 270                         src_f.layout,
 271                         MemFlags::empty(),
 272                     );
 273                 } else {
 274                     coerce_unsized_into(bx, src_f, dst_f);
 275                 }
 276             }
 277         }
 278         _ => bug!("coerce_unsized_into: invalid coercion {:?} -> {:?}", src_ty, dst_ty,),
 279     }
 280 }
 281
 282 pub fn cast_shift_expr_rhs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 283     bx: &mut Bx,
 284     op: hir::BinOpKind,
 285     lhs: Bx::Value,
 286     rhs: Bx::Value,
 287 ) -> Bx::Value {
 288     cast_shift_rhs(bx, op, lhs, rhs)
 289 }
 290
 291 fn cast_shift_rhs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 292     bx: &mut Bx,
 293     op: hir::BinOpKind,
 294     lhs: Bx::Value,
 295     rhs: Bx::Value,
 296 ) -> Bx::Value {
 297     // Shifts may have any size int on the rhs
 298     if op.is_shift() {
 299         let mut rhs_llty = bx.cx().val_ty(rhs);
 300         let mut lhs_llty = bx.cx().val_ty(lhs);
 301         if bx.cx().type_kind(rhs_llty) == TypeKind::Vector {
 302             rhs_llty = bx.cx().element_type(rhs_llty)
 303         }
 304         if bx.cx().type_kind(lhs_llty) == TypeKind::Vector {
 305             lhs_llty = bx.cx().element_type(lhs_llty)
 306         }
 307         let rhs_sz = bx.cx().int_width(rhs_llty);
 308         let lhs_sz = bx.cx().int_width(lhs_llty);
 309         if lhs_sz < rhs_sz {
 310             bx.trunc(rhs, lhs_llty)
 311         } else if lhs_sz > rhs_sz {
 312             // FIXME (#1877: If in the future shifting by negative
 313             // values is no longer undefined then this is wrong.
 314             bx.zext(rhs, lhs_llty)
 315         } else {
 316             rhs
 317         }
 318     } else {
 319         rhs
 320     }
 321 }
 322
 323 /// Returns `true` if this session's target will use SEH-based unwinding.
 324 ///
 325 /// This is only true for MSVC targets, and even then the 64-bit MSVC target
 326 /// currently uses SEH-ish unwinding with DWARF info tables to the side (same as
 327 /// 64-bit MinGW) instead of "full SEH".
 328 pub fn wants_msvc_seh(sess: &Session) -> bool {
 329     sess.target.is_like_msvc
 330 }
 331
 332 pub fn memcpy_ty<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 333     bx: &mut Bx,
 334     dst: Bx::Value,
 335     dst_align: Align,
 336     src: Bx::Value,
 337     src_align: Align,
 338     layout: TyAndLayout<'tcx>,
 339     flags: MemFlags,
 340 ) {
 341     let size = layout.size.bytes();
 342     if size == 0 {
 343         return;
 344     }
 345
 346     bx.memcpy(dst, dst_align, src, src_align, bx.cx().const_usize(size), flags);
 347 }
 348
 349 pub fn codegen_instance<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>(
 350     cx: &'a Bx::CodegenCx,
 351     instance: Instance<'tcx>,
 352 ) {
 353     // this is an info! to allow collecting monomorphization statistics
 354     // and to allow finding the last function before LLVM aborts from
 355     // release builds.
 356     info!("codegen_instance({})", instance);
 357
 358     mir::codegen_mir::<Bx>(cx, instance);
 359 }
 360
 361 /// Creates the `main` function which will initialize the rust runtime and call
 362 /// users main function.
 363 pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 364     cx: &'a Bx::CodegenCx,
 365 ) -> Option<Bx::Function> {
 366     let main_def_id = cx.tcx().entry_fn(LOCAL_CRATE).map(|(def_id, _)| def_id)?;
 367     let instance = Instance::mono(cx.tcx(), main_def_id.to_def_id());
 368
 369     if !cx.codegen_unit().contains_item(&MonoItem::Fn(instance)) {
 370         // We want to create the wrapper in the same codegen unit as Rust's main
 371         // function.
 372         return None;
 373     }
 374
 375     let main_llfn = cx.get_fn_addr(instance);
 376
 377     return cx.tcx().entry_fn(LOCAL_CRATE).map(|(_, et)| {
 378         let use_start_lang_item = EntryFnType::Start != et;
 379         create_entry_fn::<Bx>(cx, main_llfn, main_def_id, use_start_lang_item)
 380     });
 381
 382     fn create_entry_fn<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 383         cx: &'a Bx::CodegenCx,
 384         rust_main: Bx::Value,
 385         rust_main_def_id: LocalDefId,
 386         use_start_lang_item: bool,
 387     ) -> Bx::Function {
 388         // The entry function is either `int main(void)` or `int main(int argc, char **argv)`,
 389         // depending on whether the target needs `argc` and `argv` to be passed in.
 390         let llfty = if cx.sess().target.main_needs_argc_argv {
 391             cx.type_func(&[cx.type_int(), cx.type_ptr_to(cx.type_i8p())], cx.type_int())
 392         } else {
 393             cx.type_func(&[], cx.type_int())
 394         };
 395
 396         let main_ret_ty = cx.tcx().fn_sig(rust_main_def_id).output();
 397         // Given that `main()` has no arguments,
 398         // then its return type cannot have
 399         // late-bound regions, since late-bound
 400         // regions must appear in the argument
 401         // listing.
 402         let main_ret_ty = cx.tcx().erase_regions(&main_ret_ty.no_bound_vars().unwrap());
 403
 404         let llfn = match cx.declare_c_main(llfty) {
 405             Some(llfn) => llfn,
 406             None => {
 407                 // FIXME: We should be smart and show a better diagnostic here.
 408                 let span = cx.tcx().def_span(rust_main_def_id);
 409                 cx.sess()
 410                     .struct_span_err(span, "entry symbol `main` declared multiple times")
 411                     .help("did you use `#[no_mangle]` on `fn main`? Use `#[start]` instead")
 412                     .emit();
 413                 cx.sess().abort_if_errors();
 414                 bug!();
 415             }
 416         };
 417
 418         // `main` should respect same config for frame pointer elimination as rest of code
 419         cx.set_frame_pointer_elimination(llfn);
 420         cx.apply_target_cpu_attr(llfn);
 421
 422         let mut bx = Bx::new_block(&cx, llfn, "top");
 423
 424         bx.insert_reference_to_gdb_debug_scripts_section_global();
 425
 426         let (arg_argc, arg_argv) = get_argc_argv(cx, &mut bx);
 427
 428         let (start_fn, args) = if use_start_lang_item {
 429             let start_def_id = cx.tcx().require_lang_item(LangItem::Start, None);
 430             let start_fn = cx.get_fn_addr(
 431                 ty::Instance::resolve(
 432                     cx.tcx(),
 433                     ty::ParamEnv::reveal_all(),
 434                     start_def_id,
 435                     cx.tcx().intern_substs(&[main_ret_ty.into()]),
 436                 )
 437                 .unwrap()
 438                 .unwrap(),
 439             );
 440             (
 441                 start_fn,
 442                 vec![bx.pointercast(rust_main, cx.type_ptr_to(cx.type_i8p())), arg_argc, arg_argv],
 443             )
 444         } else {
 445             debug!("using user-defined start fn");
 446             (rust_main, vec![arg_argc, arg_argv])
 447         };
 448
 449         let result = bx.call(start_fn, &args, None);
 450         let cast = bx.intcast(result, cx.type_int(), true);
 451         bx.ret(cast);
 452
 453         llfn
 454     }
 455 }
 456
 457 /// Obtain the `argc` and `argv` values to pass to the rust start function.
 458 fn get_argc_argv<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 459     cx: &'a Bx::CodegenCx,
 460     bx: &mut Bx,
 461 ) -> (Bx::Value, Bx::Value) {
 462     if cx.sess().target.main_needs_argc_argv {
 463         // Params from native `main()` used as args for rust start function
 464         let param_argc = bx.get_param(0);
 465         let param_argv = bx.get_param(1);
 466         let arg_argc = bx.intcast(param_argc, cx.type_isize(), true);
 467         let arg_argv = param_argv;
 468         (arg_argc, arg_argv)
 469     } else {
 470         // The Rust start function doesn't need `argc` and `argv`, so just pass zeros.
 471         let arg_argc = bx.const_int(cx.type_int(), 0);
 472         let arg_argv = bx.const_null(cx.type_ptr_to(cx.type_i8p()));
 473         (arg_argc, arg_argv)
 474     }
 475 }
 476
 477 pub fn codegen_crate<B: ExtraBackendMethods>(
 478     backend: B,
 479     tcx: TyCtxt<'tcx>,
 480     metadata: EncodedMetadata,
 481     need_metadata_module: bool,
 482 ) -> OngoingCodegen<B> {
 483     // Skip crate items and just output metadata in -Z no-codegen mode.
 484     if tcx.sess.opts.debugging_opts.no_codegen || !tcx.sess.opts.output_types.should_codegen() {
 485         let ongoing_codegen = start_async_codegen(backend, tcx, metadata, 1);
 486
 487         ongoing_codegen.codegen_finished(tcx);
 488
 489         finalize_tcx(tcx);
 490
 491         ongoing_codegen.check_for_errors(tcx.sess);
 492
 493         return ongoing_codegen;
 494     }
 495
 496     let cgu_name_builder = &mut CodegenUnitNameBuilder::new(tcx);
 497
 498     // Run the monomorphization collector and partition the collected items into
 499     // codegen units.
 500     let codegen_units = tcx.collect_and_partition_mono_items(LOCAL_CRATE).1;
 501
 502     // Force all codegen_unit queries so they are already either red or green
 503     // when compile_codegen_unit accesses them. We are not able to re-execute
 504     // the codegen_unit query from just the DepNode, so an unknown color would
 505     // lead to having to re-execute compile_codegen_unit, possibly
 506     // unnecessarily.
 507     if tcx.dep_graph.is_fully_enabled() {
 508         for cgu in codegen_units {
 509             tcx.ensure().codegen_unit(cgu.name());
 510         }
 511     }
 512
 513     let ongoing_codegen = start_async_codegen(backend.clone(), tcx, metadata, codegen_units.len());
 514     let ongoing_codegen = AbortCodegenOnDrop::<B>(Some(ongoing_codegen));
 515
 516     // Codegen an allocator shim, if necessary.
 517     //
 518     // If the crate doesn't have an `allocator_kind` set then there's definitely
 519     // no shim to generate. Otherwise we also check our dependency graph for all
 520     // our output crate types. If anything there looks like its a `Dynamic`
 521     // linkage, then it's already got an allocator shim and we'll be using that
 522     // one instead. If nothing exists then it's our job to generate the
 523     // allocator!
 524     let any_dynamic_crate = tcx.dependency_formats(LOCAL_CRATE).iter().any(|(_, list)| {
 525         use rustc_middle::middle::dependency_format::Linkage;
 526         list.iter().any(|&linkage| linkage == Linkage::Dynamic)
 527     });
 528     let allocator_module = if any_dynamic_crate {
 529         None
 530     } else if let Some(kind) = tcx.allocator_kind() {
 531         let llmod_id =
 532             cgu_name_builder.build_cgu_name(LOCAL_CRATE, &["crate"], Some("allocator")).to_string();
 533         let mut modules = backend.new_metadata(tcx, &llmod_id);
 534         tcx.sess.time("write_allocator_module", || {
 535             backend.codegen_allocator(tcx, &mut modules, kind, tcx.lang_items().oom().is_some())
 536         });
 537
 538         Some(ModuleCodegen { name: llmod_id, module_llvm: modules, kind: ModuleKind::Allocator })
 539     } else {
 540         None
 541     };
 542
 543     if let Some(allocator_module) = allocator_module {
 544         ongoing_codegen.submit_pre_codegened_module_to_llvm(tcx, allocator_module);
 545     }
 546
 547     if need_metadata_module {
 548         // Codegen the encoded metadata.
 549         let metadata_cgu_name =
 550             cgu_name_builder.build_cgu_name(LOCAL_CRATE, &["crate"], Some("metadata")).to_string();
 551         let mut metadata_llvm_module = backend.new_metadata(tcx, &metadata_cgu_name);
 552         tcx.sess.time("write_compressed_metadata", || {
 553             backend.write_compressed_metadata(
 554                 tcx,
 555                 &ongoing_codegen.metadata,
 556                 &mut metadata_llvm_module,
 557             );
 558         });
 559
 560         let metadata_module = ModuleCodegen {
 561             name: metadata_cgu_name,
 562             module_llvm: metadata_llvm_module,
 563             kind: ModuleKind::Metadata,
 564         };
 565         ongoing_codegen.submit_pre_codegened_module_to_llvm(tcx, metadata_module);
 566     }
 567
 568     // We sort the codegen units by size. This way we can schedule work for LLVM
 569     // a bit more efficiently.
 570     let codegen_units = {
 571         let mut codegen_units = codegen_units.iter().collect::<Vec<_>>();
 572         codegen_units.sort_by_cached_key(|cgu| cmp::Reverse(cgu.size_estimate()));
 573         codegen_units
 574     };
 575
 576     let total_codegen_time = Lock::new(Duration::new(0, 0));
 577
 578     // The non-parallel compiler can only translate codegen units to LLVM IR
 579     // on a single thread, leading to a staircase effect where the N LLVM
 580     // threads have to wait on the single codegen threads to generate work
 581     // for them. The parallel compiler does not have this restriction, so
 582     // we can pre-load the LLVM queue in parallel before handing off
 583     // coordination to the OnGoingCodegen scheduler.
 584     //
 585     // This likely is a temporary measure. Once we don't have to support the
 586     // non-parallel compiler anymore, we can compile CGUs end-to-end in
 587     // parallel and get rid of the complicated scheduling logic.
 588     let pre_compile_cgus = |cgu_reuse: &[CguReuse]| {
 589         if cfg!(parallel_compiler) {
 590             tcx.sess.time("compile_first_CGU_batch", || {
 591                 // Try to find one CGU to compile per thread.
 592                 let cgus: Vec<_> = cgu_reuse
 593                     .iter()
 594                     .enumerate()
 595                     .filter(|&(_, reuse)| reuse == &CguReuse::No)
 596                     .take(tcx.sess.threads())
 597                     .collect();
 598
 599                 // Compile the found CGUs in parallel.
 600                 par_iter(cgus)
 601                     .map(|(i, _)| {
 602                         let start_time = Instant::now();
 603                         let module = backend.compile_codegen_unit(tcx, codegen_units[i].name());
 604                         let mut time = total_codegen_time.lock();
 605                         *time += start_time.elapsed();
 606                         (i, module)
 607                     })
 608                     .collect()
 609             })
 610         } else {
 611             FxHashMap::default()
 612         }
 613     };
 614
 615     let mut cgu_reuse = Vec::new();
 616     let mut pre_compiled_cgus: Option<FxHashMap<usize, _>> = None;
 617
 618     for (i, cgu) in codegen_units.iter().enumerate() {
 619         ongoing_codegen.wait_for_signal_to_codegen_item();
 620         ongoing_codegen.check_for_errors(tcx.sess);
 621
 622         // Do some setup work in the first iteration
 623         if pre_compiled_cgus.is_none() {
 624             // Calculate the CGU reuse
 625             cgu_reuse = tcx.sess.time("find_cgu_reuse", || {
 626                 codegen_units.iter().map(|cgu| determine_cgu_reuse(tcx, &cgu)).collect()
 627             });
 628             // Pre compile some CGUs
 629             pre_compiled_cgus = Some(pre_compile_cgus(&cgu_reuse));
 630         }
 631
 632         let cgu_reuse = cgu_reuse[i];
 633         tcx.sess.cgu_reuse_tracker.set_actual_reuse(&cgu.name().as_str(), cgu_reuse);
 634
 635         match cgu_reuse {
 636             CguReuse::No => {
 637                 let (module, cost) =
 638                     if let Some(cgu) = pre_compiled_cgus.as_mut().unwrap().remove(&i) {
 639                         cgu
 640                     } else {
 641                         let start_time = Instant::now();
 642                         let module = backend.compile_codegen_unit(tcx, cgu.name());
 643                         let mut time = total_codegen_time.lock();
 644                         *time += start_time.elapsed();
 645                         module
 646                     };
 647                 submit_codegened_module_to_llvm(
 648                     &backend,
 649                     &ongoing_codegen.coordinator_send,
 650                     module,
 651                     cost,
 652                 );
 653                 false
 654             }
 655             CguReuse::PreLto => {
 656                 submit_pre_lto_module_to_llvm(
 657                     &backend,
 658                     tcx,
 659                     &ongoing_codegen.coordinator_send,
 660                     CachedModuleCodegen {
 661                         name: cgu.name().to_string(),
 662                         source: cgu.work_product(tcx),
 663                     },
 664                 );
 665                 true
 666             }
 667             CguReuse::PostLto => {
 668                 submit_post_lto_module_to_llvm(
 669                     &backend,
 670                     &ongoing_codegen.coordinator_send,
 671                     CachedModuleCodegen {
 672                         name: cgu.name().to_string(),
 673                         source: cgu.work_product(tcx),
 674                     },
 675                 );
 676                 true
 677             }
 678         };
 679     }
 680
 681     ongoing_codegen.codegen_finished(tcx);
 682
 683     // Since the main thread is sometimes blocked during codegen, we keep track
 684     // -Ztime-passes output manually.
 685     print_time_passes_entry(
 686         tcx.sess.time_passes(),
 687         "codegen_to_LLVM_IR",
 688         total_codegen_time.into_inner(),
 689     );
 690
 691     rustc_incremental::assert_module_sources::assert_module_sources(tcx);
 692
 693     symbol_names_test::report_symbol_names(tcx);
 694
 695     ongoing_codegen.check_for_errors(tcx.sess);
 696
 697     finalize_tcx(tcx);
 698
 699     ongoing_codegen.into_inner()
 700 }
 701
 702 /// A curious wrapper structure whose only purpose is to call `codegen_aborted`
 703 /// when it's dropped abnormally.
 704 ///
 705 /// In the process of working on rust-lang/rust#55238 a mysterious segfault was
 706 /// stumbled upon. The segfault was never reproduced locally, but it was
 707 /// suspected to be related to the fact that codegen worker threads were
 708 /// sticking around by the time the main thread was exiting, causing issues.
 709 ///
 710 /// This structure is an attempt to fix that issue where the `codegen_aborted`
 711 /// message will block until all workers have finished. This should ensure that
 712 /// even if the main codegen thread panics we'll wait for pending work to
 713 /// complete before returning from the main thread, hopefully avoiding
 714 /// segfaults.
 715 ///
 716 /// If you see this comment in the code, then it means that this workaround
 717 /// worked! We may yet one day track down the mysterious cause of that
 718 /// segfault...
 719 struct AbortCodegenOnDrop<B: ExtraBackendMethods>(Option<OngoingCodegen<B>>);
 720
 721 impl<B: ExtraBackendMethods> AbortCodegenOnDrop<B> {
 722     fn into_inner(mut self) -> OngoingCodegen<B> {
 723         self.0.take().unwrap()
 724     }
 725 }
 726
 727 impl<B: ExtraBackendMethods> Deref for AbortCodegenOnDrop<B> {
 728     type Target = OngoingCodegen<B>;
 729
 730     fn deref(&self) -> &OngoingCodegen<B> {
 731         self.0.as_ref().unwrap()
 732     }
 733 }
 734
 735 impl<B: ExtraBackendMethods> DerefMut for AbortCodegenOnDrop<B> {
 736     fn deref_mut(&mut self) -> &mut OngoingCodegen<B> {
 737         self.0.as_mut().unwrap()
 738     }
 739 }
 740
 741 impl<B: ExtraBackendMethods> Drop for AbortCodegenOnDrop<B> {
 742     fn drop(&mut self) {
 743         if let Some(codegen) = self.0.take() {
 744             codegen.codegen_aborted();
 745         }
 746     }
 747 }
 748
 749 fn finalize_tcx(tcx: TyCtxt<'_>) {
 750     tcx.sess.time("assert_dep_graph", || rustc_incremental::assert_dep_graph(tcx));
 751     tcx.sess.time("serialize_dep_graph", || rustc_incremental::save_dep_graph(tcx));
 752
 753     // We assume that no queries are run past here. If there are new queries
 754     // after this point, they'll show up as "<unknown>" in self-profiling data.
 755     {
 756         let _prof_timer = tcx.prof.generic_activity("self_profile_alloc_query_strings");
 757         tcx.alloc_self_profile_query_strings();
 758     }
 759 }
 760
 761 impl CrateInfo {
 762     pub fn new(tcx: TyCtxt<'_>) -> CrateInfo {
 763         let mut info = CrateInfo {
 764             panic_runtime: None,
 765             compiler_builtins: None,
 766             profiler_runtime: None,
 767             is_no_builtins: Default::default(),
 768             native_libraries: Default::default(),
 769             used_libraries: tcx.native_libraries(LOCAL_CRATE),
 770             link_args: tcx.link_args(LOCAL_CRATE),
 771             crate_name: Default::default(),
 772             used_crates_dynamic: cstore::used_crates(tcx, LinkagePreference::RequireDynamic),
 773             used_crates_static: cstore::used_crates(tcx, LinkagePreference::RequireStatic),
 774             used_crate_source: Default::default(),
 775             lang_item_to_crate: Default::default(),
 776             missing_lang_items: Default::default(),
 777             dependency_formats: tcx.dependency_formats(LOCAL_CRATE),
 778         };
 779         let lang_items = tcx.lang_items();
 780
 781         let crates = tcx.crates();
 782
 783         let n_crates = crates.len();
 784         info.native_libraries.reserve(n_crates);
 785         info.crate_name.reserve(n_crates);
 786         info.used_crate_source.reserve(n_crates);
 787         info.missing_lang_items.reserve(n_crates);
 788
 789         for &cnum in crates.iter() {
 790             info.native_libraries.insert(cnum, tcx.native_libraries(cnum));
 791             info.crate_name.insert(cnum, tcx.crate_name(cnum).to_string());
 792             info.used_crate_source.insert(cnum, tcx.used_crate_source(cnum));
 793             if tcx.is_panic_runtime(cnum) {
 794                 info.panic_runtime = Some(cnum);
 795             }
 796             if tcx.is_compiler_builtins(cnum) {
 797                 info.compiler_builtins = Some(cnum);
 798             }
 799             if tcx.is_profiler_runtime(cnum) {
 800                 info.profiler_runtime = Some(cnum);
 801             }
 802             if tcx.is_no_builtins(cnum) {
 803                 info.is_no_builtins.insert(cnum);
 804             }
 805             let missing = tcx.missing_lang_items(cnum);
 806             for &item in missing.iter() {
 807                 if let Ok(id) = lang_items.require(item) {
 808                     info.lang_item_to_crate.insert(item, id.krate);
 809                 }
 810             }
 811
 812             // No need to look for lang items that don't actually need to exist.
 813             let missing =
 814                 missing.iter().cloned().filter(|&l| lang_items::required(tcx, l)).collect();
 815             info.missing_lang_items.insert(cnum, missing);
 816         }
 817
 818         info
 819     }
 820 }
 821
 822 pub fn provide_both(providers: &mut Providers) {
 823     providers.backend_optimization_level = |tcx, cratenum| {
 824         let for_speed = match tcx.sess.opts.optimize {
 825             // If globally no optimisation is done, #[optimize] has no effect.
 826             //
 827             // This is done because if we ended up "upgrading" to `-O2` here, we’d populate the
 828             // pass manager and it is likely that some module-wide passes (such as inliner or
 829             // cross-function constant propagation) would ignore the `optnone` annotation we put
 830             // on the functions, thus necessarily involving these functions into optimisations.
 831             config::OptLevel::No => return config::OptLevel::No,
 832             // If globally optimise-speed is already specified, just use that level.
 833             config::OptLevel::Less => return config::OptLevel::Less,
 834             config::OptLevel::Default => return config::OptLevel::Default,
 835             config::OptLevel::Aggressive => return config::OptLevel::Aggressive,
 836             // If globally optimize-for-size has been requested, use -O2 instead (if optimize(size)
 837             // are present).
 838             config::OptLevel::Size => config::OptLevel::Default,
 839             config::OptLevel::SizeMin => config::OptLevel::Default,
 840         };
 841
 842         let (defids, _) = tcx.collect_and_partition_mono_items(cratenum);
 843         for id in &*defids {
 844             let CodegenFnAttrs { optimize, .. } = tcx.codegen_fn_attrs(*id);
 845             match optimize {
 846                 attr::OptimizeAttr::None => continue,
 847                 attr::OptimizeAttr::Size => continue,
 848                 attr::OptimizeAttr::Speed => {
 849                     return for_speed;
 850                 }
 851             }
 852         }
 853         tcx.sess.opts.optimize
 854     };
 855
 856     providers.dllimport_foreign_items = |tcx, krate| {
 857         let module_map = tcx.foreign_modules(krate);
 858
 859         let dllimports = tcx
 860             .native_libraries(krate)
 861             .iter()
 862             .filter(|lib| {
 863                 if !matches!(lib.kind, NativeLibKind::Dylib | NativeLibKind::Unspecified) {
 864                     return false;
 865                 }
 866                 let cfg = match lib.cfg {
 867                     Some(ref cfg) => cfg,
 868                     None => return true,
 869                 };
 870                 attr::cfg_matches(cfg, &tcx.sess.parse_sess, None)
 871             })
 872             .filter_map(|lib| lib.foreign_module)
 873             .map(|id| &module_map[&id])
 874             .flat_map(|module| module.foreign_items.iter().cloned())
 875             .collect();
 876         dllimports
 877     };
 878
 879     providers.is_dllimport_foreign_item =
 880         |tcx, def_id| tcx.dllimport_foreign_items(def_id.krate).contains(&def_id);
 881 }
 882
 883 fn determine_cgu_reuse<'tcx>(tcx: TyCtxt<'tcx>, cgu: &CodegenUnit<'tcx>) -> CguReuse {
 884     if !tcx.dep_graph.is_fully_enabled() {
 885         return CguReuse::No;
 886     }
 887
 888     let work_product_id = &cgu.work_product_id();
 889     if tcx.dep_graph.previous_work_product(work_product_id).is_none() {
 890         // We don't have anything cached for this CGU. This can happen
 891         // if the CGU did not exist in the previous session.
 892         return CguReuse::No;
 893     }
 894
 895     // Try to mark the CGU as green. If it we can do so, it means that nothing
 896     // affecting the LLVM module has changed and we can re-use a cached version.
 897     // If we compile with any kind of LTO, this means we can re-use the bitcode
 898     // of the Pre-LTO stage (possibly also the Post-LTO version but we'll only
 899     // know that later). If we are not doing LTO, there is only one optimized
 900     // version of each module, so we re-use that.
 901     let dep_node = cgu.codegen_dep_node(tcx);
 902     assert!(
 903         !tcx.dep_graph.dep_node_exists(&dep_node),
 904         "CompileCodegenUnit dep-node for CGU `{}` already exists before marking.",
 905         cgu.name()
 906     );
 907
 908     if tcx.dep_graph.try_mark_green(tcx, &dep_node).is_some() {
 909         // We can re-use either the pre- or the post-thinlto state. If no LTO is
 910         // being performed then we can use post-LTO artifacts, otherwise we must
 911         // reuse pre-LTO artifacts
 912         match compute_per_cgu_lto_type(
 913             &tcx.sess.lto(),
 914             &tcx.sess.opts,
 915             &tcx.sess.crate_types(),
 916             ModuleKind::Regular,
 917         ) {
 918             ComputedLtoType::No => CguReuse::PostLto,
 919             _ => CguReuse::PreLto,
 920         }
 921     } else {
 922         CguReuse::No
 923     }
 924 }