compiler/rustc_codegen_ssa/src/base.rs

   1 use crate::assert_module_sources::CguReuse;
   2 use crate::back::link::are_upstream_rust_objects_already_included;
   3 use crate::back::metadata::create_compressed_metadata_file;
   4 use crate::back::write::{
   5     compute_per_cgu_lto_type, start_async_codegen, submit_codegened_module_to_llvm,
   6     submit_post_lto_module_to_llvm, submit_pre_lto_module_to_llvm, ComputedLtoType, OngoingCodegen,
   7 };
   8 use crate::common::{IntPredicate, RealPredicate, TypeKind};
   9 use crate::errors;
  10 use crate::meth;
  11 use crate::mir;
  12 use crate::mir::operand::OperandValue;
  13 use crate::mir::place::PlaceRef;
  14 use crate::traits::*;
  15 use crate::{CachedModuleCodegen, CompiledModule, CrateInfo, MemFlags, ModuleCodegen, ModuleKind};
  16
  17 use rustc_ast::expand::allocator::{global_fn_name, AllocatorKind, ALLOCATOR_METHODS};
  18 use rustc_attr as attr;
  19 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
  20 use rustc_data_structures::profiling::{get_resident_set_size, print_time_passes_entry};
  21 use rustc_data_structures::sync::par_map;
  22 use rustc_hir as hir;
  23 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
  24 use rustc_hir::lang_items::LangItem;
  25 use rustc_metadata::EncodedMetadata;
  26 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
  27 use rustc_middle::middle::debugger_visualizer::{DebuggerVisualizerFile, DebuggerVisualizerType};
  28 use rustc_middle::middle::exported_symbols;
  29 use rustc_middle::middle::exported_symbols::SymbolExportKind;
  30 use rustc_middle::middle::lang_items;
  31 use rustc_middle::mir::mono::{CodegenUnit, CodegenUnitNameBuilder, MonoItem};
  32 use rustc_middle::query::Providers;
  33 use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, TyAndLayout};
  34 use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
  35 use rustc_session::config::{self, CrateType, EntryFnType, OutputType};
  36 use rustc_session::Session;
  37 use rustc_span::symbol::sym;
  38 use rustc_span::Symbol;
  39 use rustc_target::abi::{Align, FIRST_VARIANT};
  40
  41 use std::cmp;
  42 use std::collections::BTreeSet;
  43 use std::time::{Duration, Instant};
  44
  45 use itertools::Itertools;
  46
  47 pub fn bin_op_to_icmp_predicate(op: hir::BinOpKind, signed: bool) -> IntPredicate {
  48     match op {
  49         hir::BinOpKind::Eq => IntPredicate::IntEQ,
  50         hir::BinOpKind::Ne => IntPredicate::IntNE,
  51         hir::BinOpKind::Lt => {
  52             if signed {
  53                 IntPredicate::IntSLT
  54             } else {
  55                 IntPredicate::IntULT
  56             }
  57         }
  58         hir::BinOpKind::Le => {
  59             if signed {
  60                 IntPredicate::IntSLE
  61             } else {
  62                 IntPredicate::IntULE
  63             }
  64         }
  65         hir::BinOpKind::Gt => {
  66             if signed {
  67                 IntPredicate::IntSGT
  68             } else {
  69                 IntPredicate::IntUGT
  70             }
  71         }
  72         hir::BinOpKind::Ge => {
  73             if signed {
  74                 IntPredicate::IntSGE
  75             } else {
  76                 IntPredicate::IntUGE
  77             }
  78         }
  79         op => bug!(
  80             "comparison_op_to_icmp_predicate: expected comparison operator, \
  81              found {:?}",
  82             op
  83         ),
  84     }
  85 }
  86
  87 pub fn bin_op_to_fcmp_predicate(op: hir::BinOpKind) -> RealPredicate {
  88     match op {
  89         hir::BinOpKind::Eq => RealPredicate::RealOEQ,
  90         hir::BinOpKind::Ne => RealPredicate::RealUNE,
  91         hir::BinOpKind::Lt => RealPredicate::RealOLT,
  92         hir::BinOpKind::Le => RealPredicate::RealOLE,
  93         hir::BinOpKind::Gt => RealPredicate::RealOGT,
  94         hir::BinOpKind::Ge => RealPredicate::RealOGE,
  95         op => {
  96             bug!(
  97                 "comparison_op_to_fcmp_predicate: expected comparison operator, \
  98                  found {:?}",
  99                 op
 100             );
 101         }
 102     }
 103 }
 104
 105 pub fn compare_simd_types<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 106     bx: &mut Bx,
 107     lhs: Bx::Value,
 108     rhs: Bx::Value,
 109     t: Ty<'tcx>,
 110     ret_ty: Bx::Type,
 111     op: hir::BinOpKind,
 112 ) -> Bx::Value {
 113     let signed = match t.kind() {
 114         ty::Float(_) => {
 115             let cmp = bin_op_to_fcmp_predicate(op);
 116             let cmp = bx.fcmp(cmp, lhs, rhs);
 117             return bx.sext(cmp, ret_ty);
 118         }
 119         ty::Uint(_) => false,
 120         ty::Int(_) => true,
 121         _ => bug!("compare_simd_types: invalid SIMD type"),
 122     };
 123
 124     let cmp = bin_op_to_icmp_predicate(op, signed);
 125     let cmp = bx.icmp(cmp, lhs, rhs);
 126     // LLVM outputs an `< size x i1 >`, so we need to perform a sign extension
 127     // to get the correctly sized type. This will compile to a single instruction
 128     // once the IR is converted to assembly if the SIMD instruction is supported
 129     // by the target architecture.
 130     bx.sext(cmp, ret_ty)
 131 }
 132
 133 /// Retrieves the information we are losing (making dynamic) in an unsizing
 134 /// adjustment.
 135 ///
 136 /// The `old_info` argument is a bit odd. It is intended for use in an upcast,
 137 /// where the new vtable for an object will be derived from the old one.
 138 pub fn unsized_info<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 139     bx: &mut Bx,
 140     source: Ty<'tcx>,
 141     target: Ty<'tcx>,
 142     old_info: Option<Bx::Value>,
 143 ) -> Bx::Value {
 144     let cx = bx.cx();
 145     let (source, target) =
 146         cx.tcx().struct_lockstep_tails_erasing_lifetimes(source, target, bx.param_env());
 147     match (source.kind(), target.kind()) {
 148         (&ty::Array(_, len), &ty::Slice(_)) => {
 149             cx.const_usize(len.eval_target_usize(cx.tcx(), ty::ParamEnv::reveal_all()))
 150         }
 151         (&ty::Dynamic(data_a, _, src_dyn_kind), &ty::Dynamic(data_b, _, target_dyn_kind))
 152             if src_dyn_kind == target_dyn_kind =>
 153         {
 154             let old_info =
 155                 old_info.expect("unsized_info: missing old info for trait upcasting coercion");
 156             if data_a.principal_def_id() == data_b.principal_def_id() {
 157                 // A NOP cast that doesn't actually change anything, should be allowed even with invalid vtables.
 158                 return old_info;
 159             }
 160
 161             // trait upcasting coercion
 162
 163             let vptr_entry_idx =
 164                 cx.tcx().vtable_trait_upcasting_coercion_new_vptr_slot((source, target));
 165
 166             if let Some(entry_idx) = vptr_entry_idx {
 167                 let ptr_ty = cx.type_ptr();
 168                 let ptr_align = cx.tcx().data_layout.pointer_align.abi;
 169                 let gep = bx.inbounds_gep(
 170                     ptr_ty,
 171                     old_info,
 172                     &[bx.const_usize(u64::try_from(entry_idx).unwrap())],
 173                 );
 174                 let new_vptr = bx.load(ptr_ty, gep, ptr_align);
 175                 bx.nonnull_metadata(new_vptr);
 176                 // VTable loads are invariant.
 177                 bx.set_invariant_load(new_vptr);
 178                 new_vptr
 179             } else {
 180                 old_info
 181             }
 182         }
 183         (_, ty::Dynamic(data, _, _)) => meth::get_vtable(cx, source, data.principal()),
 184         _ => bug!("unsized_info: invalid unsizing {:?} -> {:?}", source, target),
 185     }
 186 }
 187
 188 /// Coerces `src` to `dst_ty`. `src_ty` must be a pointer.
 189 pub fn unsize_ptr<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 190     bx: &mut Bx,
 191     src: Bx::Value,
 192     src_ty: Ty<'tcx>,
 193     dst_ty: Ty<'tcx>,
 194     old_info: Option<Bx::Value>,
 195 ) -> (Bx::Value, Bx::Value) {
 196     debug!("unsize_ptr: {:?} => {:?}", src_ty, dst_ty);
 197     match (src_ty.kind(), dst_ty.kind()) {
 198         (&ty::Ref(_, a, _), &ty::Ref(_, b, _) | &ty::RawPtr(ty::TypeAndMut { ty: b, .. }))
 199         | (&ty::RawPtr(ty::TypeAndMut { ty: a, .. }), &ty::RawPtr(ty::TypeAndMut { ty: b, .. })) => {
 200             assert_eq!(bx.cx().type_is_sized(a), old_info.is_none());
 201             (src, unsized_info(bx, a, b, old_info))
 202         }
 203         (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => {
 204             assert_eq!(def_a, def_b); // implies same number of fields
 205             let src_layout = bx.cx().layout_of(src_ty);
 206             let dst_layout = bx.cx().layout_of(dst_ty);
 207             if src_ty == dst_ty {
 208                 return (src, old_info.unwrap());
 209             }
 210             let mut result = None;
 211             for i in 0..src_layout.fields.count() {
 212                 let src_f = src_layout.field(bx.cx(), i);
 213                 if src_f.is_1zst() {
 214                     // We are looking for the one non-1-ZST field; this is not it.
 215                     continue;
 216                 }
 217
 218                 assert_eq!(src_layout.fields.offset(i).bytes(), 0);
 219                 assert_eq!(dst_layout.fields.offset(i).bytes(), 0);
 220                 assert_eq!(src_layout.size, src_f.size);
 221
 222                 let dst_f = dst_layout.field(bx.cx(), i);
 223                 assert_ne!(src_f.ty, dst_f.ty);
 224                 assert_eq!(result, None);
 225                 result = Some(unsize_ptr(bx, src, src_f.ty, dst_f.ty, old_info));
 226             }
 227             result.unwrap()
 228         }
 229         _ => bug!("unsize_ptr: called on bad types"),
 230     }
 231 }
 232
 233 /// Coerces `src` to `dst_ty` which is guaranteed to be a `dyn*` type.
 234 pub fn cast_to_dyn_star<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 235     bx: &mut Bx,
 236     src: Bx::Value,
 237     src_ty_and_layout: TyAndLayout<'tcx>,
 238     dst_ty: Ty<'tcx>,
 239     old_info: Option<Bx::Value>,
 240 ) -> (Bx::Value, Bx::Value) {
 241     debug!("cast_to_dyn_star: {:?} => {:?}", src_ty_and_layout.ty, dst_ty);
 242     assert!(
 243         matches!(dst_ty.kind(), ty::Dynamic(_, _, ty::DynStar)),
 244         "destination type must be a dyn*"
 245     );
 246     let src = match bx.cx().type_kind(bx.cx().backend_type(src_ty_and_layout)) {
 247         TypeKind::Pointer => src,
 248         TypeKind::Integer => bx.inttoptr(src, bx.type_ptr()),
 249         // FIXME(dyn-star): We probably have to do a bitcast first, then inttoptr.
 250         kind => bug!("unexpected TypeKind for left-hand side of `dyn*` cast: {kind:?}"),
 251     };
 252     (src, unsized_info(bx, src_ty_and_layout.ty, dst_ty, old_info))
 253 }
 254
 255 /// Coerces `src`, which is a reference to a value of type `src_ty`,
 256 /// to a value of type `dst_ty`, and stores the result in `dst`.
 257 pub fn coerce_unsized_into<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 258     bx: &mut Bx,
 259     src: PlaceRef<'tcx, Bx::Value>,
 260     dst: PlaceRef<'tcx, Bx::Value>,
 261 ) {
 262     let src_ty = src.layout.ty;
 263     let dst_ty = dst.layout.ty;
 264     match (src_ty.kind(), dst_ty.kind()) {
 265         (&ty::Ref(..), &ty::Ref(..) | &ty::RawPtr(..)) | (&ty::RawPtr(..), &ty::RawPtr(..)) => {
 266             let (base, info) = match bx.load_operand(src).val {
 267                 OperandValue::Pair(base, info) => unsize_ptr(bx, base, src_ty, dst_ty, Some(info)),
 268                 OperandValue::Immediate(base) => unsize_ptr(bx, base, src_ty, dst_ty, None),
 269                 OperandValue::Ref(..) | OperandValue::ZeroSized => bug!(),
 270             };
 271             OperandValue::Pair(base, info).store(bx, dst);
 272         }
 273
 274         (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => {
 275             assert_eq!(def_a, def_b); // implies same number of fields
 276
 277             for i in def_a.variant(FIRST_VARIANT).fields.indices() {
 278                 let src_f = src.project_field(bx, i.as_usize());
 279                 let dst_f = dst.project_field(bx, i.as_usize());
 280
 281                 if dst_f.layout.is_zst() {
 282                     // No data here, nothing to copy/coerce.
 283                     continue;
 284                 }
 285
 286                 if src_f.layout.ty == dst_f.layout.ty {
 287                     memcpy_ty(
 288                         bx,
 289                         dst_f.llval,
 290                         dst_f.align,
 291                         src_f.llval,
 292                         src_f.align,
 293                         src_f.layout,
 294                         MemFlags::empty(),
 295                     );
 296                 } else {
 297                     coerce_unsized_into(bx, src_f, dst_f);
 298                 }
 299             }
 300         }
 301         _ => bug!("coerce_unsized_into: invalid coercion {:?} -> {:?}", src_ty, dst_ty,),
 302     }
 303 }
 304
 305 pub fn cast_shift_expr_rhs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 306     bx: &mut Bx,
 307     lhs: Bx::Value,
 308     rhs: Bx::Value,
 309 ) -> Bx::Value {
 310     // Shifts may have any size int on the rhs
 311     let mut rhs_llty = bx.cx().val_ty(rhs);
 312     let mut lhs_llty = bx.cx().val_ty(lhs);
 313     if bx.cx().type_kind(rhs_llty) == TypeKind::Vector {
 314         rhs_llty = bx.cx().element_type(rhs_llty)
 315     }
 316     if bx.cx().type_kind(lhs_llty) == TypeKind::Vector {
 317         lhs_llty = bx.cx().element_type(lhs_llty)
 318     }
 319     let rhs_sz = bx.cx().int_width(rhs_llty);
 320     let lhs_sz = bx.cx().int_width(lhs_llty);
 321     if lhs_sz < rhs_sz {
 322         bx.trunc(rhs, lhs_llty)
 323     } else if lhs_sz > rhs_sz {
 324         // We zero-extend even if the RHS is signed. So e.g. `(x: i32) << -1i8` will zero-extend the
 325         // RHS to `255i32`. But then we mask the shift amount to be within the size of the LHS
 326         // anyway so the result is `31` as it should be. All the extra bits introduced by zext
 327         // are masked off so their value does not matter.
 328         // FIXME: if we ever support 512bit integers, this will be wrong! For such large integers,
 329         // the extra bits introduced by zext are *not* all masked away any more.
 330         assert!(lhs_sz <= 256);
 331         bx.zext(rhs, lhs_llty)
 332     } else {
 333         rhs
 334     }
 335 }
 336
 337 // Returns `true` if this session's target will use native wasm
 338 // exceptions. This means that the VM does the unwinding for
 339 // us
 340 pub fn wants_wasm_eh(sess: &Session) -> bool {
 341     sess.target.is_like_wasm && sess.target.os != "emscripten"
 342 }
 343
 344 /// Returns `true` if this session's target will use SEH-based unwinding.
 345 ///
 346 /// This is only true for MSVC targets, and even then the 64-bit MSVC target
 347 /// currently uses SEH-ish unwinding with DWARF info tables to the side (same as
 348 /// 64-bit MinGW) instead of "full SEH".
 349 pub fn wants_msvc_seh(sess: &Session) -> bool {
 350     sess.target.is_like_msvc
 351 }
 352
 353 /// Returns `true` if this session's target requires the new exception
 354 /// handling LLVM IR instructions (catchpad / cleanuppad / ... instead
 355 /// of landingpad)
 356 pub fn wants_new_eh_instructions(sess: &Session) -> bool {
 357     wants_wasm_eh(sess) || wants_msvc_seh(sess)
 358 }
 359
 360 pub fn memcpy_ty<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 361     bx: &mut Bx,
 362     dst: Bx::Value,
 363     dst_align: Align,
 364     src: Bx::Value,
 365     src_align: Align,
 366     layout: TyAndLayout<'tcx>,
 367     flags: MemFlags,
 368 ) {
 369     let size = layout.size.bytes();
 370     if size == 0 {
 371         return;
 372     }
 373
 374     if flags == MemFlags::empty()
 375         && let Some(bty) = bx.cx().scalar_copy_backend_type(layout)
 376     {
 377         let temp = bx.load(bty, src, src_align);
 378         bx.store(temp, dst, dst_align);
 379     } else {
 380         bx.memcpy(dst, dst_align, src, src_align, bx.cx().const_usize(size), flags);
 381     }
 382 }
 383
 384 pub fn codegen_instance<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>(
 385     cx: &'a Bx::CodegenCx,
 386     instance: Instance<'tcx>,
 387 ) {
 388     // this is an info! to allow collecting monomorphization statistics
 389     // and to allow finding the last function before LLVM aborts from
 390     // release builds.
 391     info!("codegen_instance({})", instance);
 392
 393     mir::codegen_mir::<Bx>(cx, instance);
 394 }
 395
 396 /// Creates the `main` function which will initialize the rust runtime and call
 397 /// users main function.
 398 pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 399     cx: &'a Bx::CodegenCx,
 400 ) -> Option<Bx::Function> {
 401     let (main_def_id, entry_type) = cx.tcx().entry_fn(())?;
 402     let main_is_local = main_def_id.is_local();
 403     let instance = Instance::mono(cx.tcx(), main_def_id);
 404
 405     if main_is_local {
 406         // We want to create the wrapper in the same codegen unit as Rust's main
 407         // function.
 408         if !cx.codegen_unit().contains_item(&MonoItem::Fn(instance)) {
 409             return None;
 410         }
 411     } else if !cx.codegen_unit().is_primary() {
 412         // We want to create the wrapper only when the codegen unit is the primary one
 413         return None;
 414     }
 415
 416     let main_llfn = cx.get_fn_addr(instance);
 417
 418     let entry_fn = create_entry_fn::<Bx>(cx, main_llfn, main_def_id, entry_type);
 419     return Some(entry_fn);
 420
 421     fn create_entry_fn<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 422         cx: &'a Bx::CodegenCx,
 423         rust_main: Bx::Value,
 424         rust_main_def_id: DefId,
 425         entry_type: EntryFnType,
 426     ) -> Bx::Function {
 427         // The entry function is either `int main(void)` or `int main(int argc, char **argv)`, or
 428         // `usize efi_main(void *handle, void *system_table)` depending on the target.
 429         let llfty = if cx.sess().target.os.contains("uefi") {
 430             cx.type_func(&[cx.type_ptr(), cx.type_ptr()], cx.type_isize())
 431         } else if cx.sess().target.main_needs_argc_argv {
 432             cx.type_func(&[cx.type_int(), cx.type_ptr()], cx.type_int())
 433         } else {
 434             cx.type_func(&[], cx.type_int())
 435         };
 436
 437         let main_ret_ty = cx.tcx().fn_sig(rust_main_def_id).no_bound_vars().unwrap().output();
 438         // Given that `main()` has no arguments,
 439         // then its return type cannot have
 440         // late-bound regions, since late-bound
 441         // regions must appear in the argument
 442         // listing.
 443         let main_ret_ty = cx.tcx().normalize_erasing_regions(
 444             ty::ParamEnv::reveal_all(),
 445             main_ret_ty.no_bound_vars().unwrap(),
 446         );
 447
 448         let Some(llfn) = cx.declare_c_main(llfty) else {
 449             // FIXME: We should be smart and show a better diagnostic here.
 450             let span = cx.tcx().def_span(rust_main_def_id);
 451             let dcx = cx.tcx().dcx();
 452             dcx.emit_err(errors::MultipleMainFunctions { span });
 453             dcx.abort_if_errors();
 454             bug!();
 455         };
 456
 457         // `main` should respect same config for frame pointer elimination as rest of code
 458         cx.set_frame_pointer_type(llfn);
 459         cx.apply_target_cpu_attr(llfn);
 460
 461         let llbb = Bx::append_block(cx, llfn, "top");
 462         let mut bx = Bx::build(cx, llbb);
 463
 464         bx.insert_reference_to_gdb_debug_scripts_section_global();
 465
 466         let isize_ty = cx.type_isize();
 467         let ptr_ty = cx.type_ptr();
 468         let (arg_argc, arg_argv) = get_argc_argv(cx, &mut bx);
 469
 470         let (start_fn, start_ty, args) = if let EntryFnType::Main { sigpipe } = entry_type {
 471             let start_def_id = cx.tcx().require_lang_item(LangItem::Start, None);
 472             let start_fn = cx.get_fn_addr(
 473                 ty::Instance::resolve(
 474                     cx.tcx(),
 475                     ty::ParamEnv::reveal_all(),
 476                     start_def_id,
 477                     cx.tcx().mk_args(&[main_ret_ty.into()]),
 478                 )
 479                 .unwrap()
 480                 .unwrap(),
 481             );
 482
 483             let i8_ty = cx.type_i8();
 484             let arg_sigpipe = bx.const_u8(sigpipe);
 485
 486             let start_ty = cx.type_func(&[cx.val_ty(rust_main), isize_ty, ptr_ty, i8_ty], isize_ty);
 487             (start_fn, start_ty, vec![rust_main, arg_argc, arg_argv, arg_sigpipe])
 488         } else {
 489             debug!("using user-defined start fn");
 490             let start_ty = cx.type_func(&[isize_ty, ptr_ty], isize_ty);
 491             (rust_main, start_ty, vec![arg_argc, arg_argv])
 492         };
 493
 494         let result = bx.call(start_ty, None, None, start_fn, &args, None);
 495         if cx.sess().target.os.contains("uefi") {
 496             bx.ret(result);
 497         } else {
 498             let cast = bx.intcast(result, cx.type_int(), true);
 499             bx.ret(cast);
 500         }
 501
 502         llfn
 503     }
 504 }
 505
 506 /// Obtain the `argc` and `argv` values to pass to the rust start function.
 507 fn get_argc_argv<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 508     cx: &'a Bx::CodegenCx,
 509     bx: &mut Bx,
 510 ) -> (Bx::Value, Bx::Value) {
 511     if cx.sess().target.os.contains("uefi") {
 512         // Params for UEFI
 513         let param_handle = bx.get_param(0);
 514         let param_system_table = bx.get_param(1);
 515         let arg_argc = bx.const_int(cx.type_isize(), 2);
 516         let arg_argv = bx.alloca(cx.type_array(cx.type_ptr(), 2), Align::ONE);
 517         bx.store(param_handle, arg_argv, Align::ONE);
 518         let arg_argv_el1 = bx.gep(cx.type_ptr(), arg_argv, &[bx.const_int(cx.type_int(), 1)]);
 519         bx.store(param_system_table, arg_argv_el1, Align::ONE);
 520         (arg_argc, arg_argv)
 521     } else if cx.sess().target.main_needs_argc_argv {
 522         // Params from native `main()` used as args for rust start function
 523         let param_argc = bx.get_param(0);
 524         let param_argv = bx.get_param(1);
 525         let arg_argc = bx.intcast(param_argc, cx.type_isize(), true);
 526         let arg_argv = param_argv;
 527         (arg_argc, arg_argv)
 528     } else {
 529         // The Rust start function doesn't need `argc` and `argv`, so just pass zeros.
 530         let arg_argc = bx.const_int(cx.type_int(), 0);
 531         let arg_argv = bx.const_null(cx.type_ptr());
 532         (arg_argc, arg_argv)
 533     }
 534 }
 535
 536 /// This function returns all of the debugger visualizers specified for the
 537 /// current crate as well as all upstream crates transitively that match the
 538 /// `visualizer_type` specified.
 539 pub fn collect_debugger_visualizers_transitive(
 540     tcx: TyCtxt<'_>,
 541     visualizer_type: DebuggerVisualizerType,
 542 ) -> BTreeSet<DebuggerVisualizerFile> {
 543     tcx.debugger_visualizers(LOCAL_CRATE)
 544         .iter()
 545         .chain(
 546             tcx.crates(())
 547                 .iter()
 548                 .filter(|&cnum| {
 549                     let used_crate_source = tcx.used_crate_source(*cnum);
 550                     used_crate_source.rlib.is_some() || used_crate_source.rmeta.is_some()
 551                 })
 552                 .flat_map(|&cnum| tcx.debugger_visualizers(cnum)),
 553         )
 554         .filter(|visualizer| visualizer.visualizer_type == visualizer_type)
 555         .cloned()
 556         .collect::<BTreeSet<_>>()
 557 }
 558
 559 /// Decide allocator kind to codegen. If `Some(_)` this will be the same as
 560 /// `tcx.allocator_kind`, but it may be `None` in more cases (e.g. if using
 561 /// allocator definitions from a dylib dependency).
 562 pub fn allocator_kind_for_codegen(tcx: TyCtxt<'_>) -> Option<AllocatorKind> {
 563     // If the crate doesn't have an `allocator_kind` set then there's definitely
 564     // no shim to generate. Otherwise we also check our dependency graph for all
 565     // our output crate types. If anything there looks like its a `Dynamic`
 566     // linkage, then it's already got an allocator shim and we'll be using that
 567     // one instead. If nothing exists then it's our job to generate the
 568     // allocator!
 569     let any_dynamic_crate = tcx.dependency_formats(()).iter().any(|(_, list)| {
 570         use rustc_middle::middle::dependency_format::Linkage;
 571         list.iter().any(|&linkage| linkage == Linkage::Dynamic)
 572     });
 573     if any_dynamic_crate { None } else { tcx.allocator_kind(()) }
 574 }
 575
 576 pub fn codegen_crate<B: ExtraBackendMethods>(
 577     backend: B,
 578     tcx: TyCtxt<'_>,
 579     target_cpu: String,
 580     metadata: EncodedMetadata,
 581     need_metadata_module: bool,
 582 ) -> OngoingCodegen<B> {
 583     // Skip crate items and just output metadata in -Z no-codegen mode.
 584     if tcx.sess.opts.unstable_opts.no_codegen || !tcx.sess.opts.output_types.should_codegen() {
 585         let ongoing_codegen = start_async_codegen(backend, tcx, target_cpu, metadata, None);
 586
 587         ongoing_codegen.codegen_finished(tcx);
 588
 589         ongoing_codegen.check_for_errors(tcx.sess);
 590
 591         return ongoing_codegen;
 592     }
 593
 594     let cgu_name_builder = &mut CodegenUnitNameBuilder::new(tcx);
 595
 596     // Run the monomorphization collector and partition the collected items into
 597     // codegen units.
 598     let codegen_units = tcx.collect_and_partition_mono_items(()).1;
 599
 600     // Force all codegen_unit queries so they are already either red or green
 601     // when compile_codegen_unit accesses them. We are not able to re-execute
 602     // the codegen_unit query from just the DepNode, so an unknown color would
 603     // lead to having to re-execute compile_codegen_unit, possibly
 604     // unnecessarily.
 605     if tcx.dep_graph.is_fully_enabled() {
 606         for cgu in codegen_units {
 607             tcx.ensure().codegen_unit(cgu.name());
 608         }
 609     }
 610
 611     let metadata_module = need_metadata_module.then(|| {
 612         // Emit compressed metadata object.
 613         let metadata_cgu_name =
 614             cgu_name_builder.build_cgu_name(LOCAL_CRATE, &["crate"], Some("metadata")).to_string();
 615         tcx.sess.time("write_compressed_metadata", || {
 616             let file_name =
 617                 tcx.output_filenames(()).temp_path(OutputType::Metadata, Some(&metadata_cgu_name));
 618             let data = create_compressed_metadata_file(
 619                 tcx.sess,
 620                 &metadata,
 621                 &exported_symbols::metadata_symbol_name(tcx),
 622             );
 623             if let Err(error) = std::fs::write(&file_name, data) {
 624                 tcx.dcx().emit_fatal(errors::MetadataObjectFileWrite { error });
 625             }
 626             CompiledModule {
 627                 name: metadata_cgu_name,
 628                 kind: ModuleKind::Metadata,
 629                 object: Some(file_name),
 630                 dwarf_object: None,
 631                 bytecode: None,
 632             }
 633         })
 634     });
 635
 636     let ongoing_codegen =
 637         start_async_codegen(backend.clone(), tcx, target_cpu, metadata, metadata_module);
 638
 639     // Codegen an allocator shim, if necessary.
 640     if let Some(kind) = allocator_kind_for_codegen(tcx) {
 641         let llmod_id =
 642             cgu_name_builder.build_cgu_name(LOCAL_CRATE, &["crate"], Some("allocator")).to_string();
 643         let module_llvm = tcx.sess.time("write_allocator_module", || {
 644             backend.codegen_allocator(
 645                 tcx,
 646                 &llmod_id,
 647                 kind,
 648                 // If allocator_kind is Some then alloc_error_handler_kind must
 649                 // also be Some.
 650                 tcx.alloc_error_handler_kind(()).unwrap(),
 651             )
 652         });
 653
 654         ongoing_codegen.wait_for_signal_to_codegen_item();
 655         ongoing_codegen.check_for_errors(tcx.sess);
 656
 657         // These modules are generally cheap and won't throw off scheduling.
 658         let cost = 0;
 659         submit_codegened_module_to_llvm(
 660             &backend,
 661             &ongoing_codegen.coordinator.sender,
 662             ModuleCodegen { name: llmod_id, module_llvm, kind: ModuleKind::Allocator },
 663             cost,
 664         );
 665     }
 666
 667     // For better throughput during parallel processing by LLVM, we used to sort
 668     // CGUs largest to smallest. This would lead to better thread utilization
 669     // by, for example, preventing a large CGU from being processed last and
 670     // having only one LLVM thread working while the rest remained idle.
 671     //
 672     // However, this strategy would lead to high memory usage, as it meant the
 673     // LLVM-IR for all of the largest CGUs would be resident in memory at once.
 674     //
 675     // Instead, we can compromise by ordering CGUs such that the largest and
 676     // smallest are first, second largest and smallest are next, etc. If there
 677     // are large size variations, this can reduce memory usage significantly.
 678     let codegen_units: Vec<_> = {
 679         let mut sorted_cgus = codegen_units.iter().collect::<Vec<_>>();
 680         sorted_cgus.sort_by_key(|cgu| cmp::Reverse(cgu.size_estimate()));
 681
 682         let (first_half, second_half) = sorted_cgus.split_at(sorted_cgus.len() / 2);
 683         first_half.iter().interleave(second_half.iter().rev()).copied().collect()
 684     };
 685
 686     // Calculate the CGU reuse
 687     let cgu_reuse = tcx.sess.time("find_cgu_reuse", || {
 688         codegen_units.iter().map(|cgu| determine_cgu_reuse(tcx, cgu)).collect::<Vec<_>>()
 689     });
 690
 691     crate::assert_module_sources::assert_module_sources(tcx, &|cgu_reuse_tracker| {
 692         for (i, cgu) in codegen_units.iter().enumerate() {
 693             let cgu_reuse = cgu_reuse[i];
 694             cgu_reuse_tracker.set_actual_reuse(cgu.name().as_str(), cgu_reuse);
 695         }
 696     });
 697
 698     let mut total_codegen_time = Duration::new(0, 0);
 699     let start_rss = tcx.sess.opts.unstable_opts.time_passes.then(|| get_resident_set_size());
 700
 701     // The non-parallel compiler can only translate codegen units to LLVM IR
 702     // on a single thread, leading to a staircase effect where the N LLVM
 703     // threads have to wait on the single codegen threads to generate work
 704     // for them. The parallel compiler does not have this restriction, so
 705     // we can pre-load the LLVM queue in parallel before handing off
 706     // coordination to the OnGoingCodegen scheduler.
 707     //
 708     // This likely is a temporary measure. Once we don't have to support the
 709     // non-parallel compiler anymore, we can compile CGUs end-to-end in
 710     // parallel and get rid of the complicated scheduling logic.
 711     let mut pre_compiled_cgus = if tcx.sess.threads() > 1 {
 712         tcx.sess.time("compile_first_CGU_batch", || {
 713             // Try to find one CGU to compile per thread.
 714             let cgus: Vec<_> = cgu_reuse
 715                 .iter()
 716                 .enumerate()
 717                 .filter(|&(_, reuse)| reuse == &CguReuse::No)
 718                 .take(tcx.sess.threads())
 719                 .collect();
 720
 721             // Compile the found CGUs in parallel.
 722             let start_time = Instant::now();
 723
 724             let pre_compiled_cgus = par_map(cgus, |(i, _)| {
 725                 let module = backend.compile_codegen_unit(tcx, codegen_units[i].name());
 726                 (i, module)
 727             });
 728
 729             total_codegen_time += start_time.elapsed();
 730
 731             pre_compiled_cgus
 732         })
 733     } else {
 734         FxHashMap::default()
 735     };
 736
 737     for (i, cgu) in codegen_units.iter().enumerate() {
 738         ongoing_codegen.wait_for_signal_to_codegen_item();
 739         ongoing_codegen.check_for_errors(tcx.sess);
 740
 741         let cgu_reuse = cgu_reuse[i];
 742
 743         match cgu_reuse {
 744             CguReuse::No => {
 745                 let (module, cost) = if let Some(cgu) = pre_compiled_cgus.remove(&i) {
 746                     cgu
 747                 } else {
 748                     let start_time = Instant::now();
 749                     let module = backend.compile_codegen_unit(tcx, cgu.name());
 750                     total_codegen_time += start_time.elapsed();
 751                     module
 752                 };
 753                 // This will unwind if there are errors, which triggers our `AbortCodegenOnDrop`
 754                 // guard. Unfortunately, just skipping the `submit_codegened_module_to_llvm` makes
 755                 // compilation hang on post-monomorphization errors.
 756                 tcx.dcx().abort_if_errors();
 757
 758                 submit_codegened_module_to_llvm(
 759                     &backend,
 760                     &ongoing_codegen.coordinator.sender,
 761                     module,
 762                     cost,
 763                 );
 764             }
 765             CguReuse::PreLto => {
 766                 submit_pre_lto_module_to_llvm(
 767                     &backend,
 768                     tcx,
 769                     &ongoing_codegen.coordinator.sender,
 770                     CachedModuleCodegen {
 771                         name: cgu.name().to_string(),
 772                         source: cgu.previous_work_product(tcx),
 773                     },
 774                 );
 775             }
 776             CguReuse::PostLto => {
 777                 submit_post_lto_module_to_llvm(
 778                     &backend,
 779                     &ongoing_codegen.coordinator.sender,
 780                     CachedModuleCodegen {
 781                         name: cgu.name().to_string(),
 782                         source: cgu.previous_work_product(tcx),
 783                     },
 784                 );
 785             }
 786         }
 787     }
 788
 789     ongoing_codegen.codegen_finished(tcx);
 790
 791     // Since the main thread is sometimes blocked during codegen, we keep track
 792     // -Ztime-passes output manually.
 793     if tcx.sess.opts.unstable_opts.time_passes {
 794         let end_rss = get_resident_set_size();
 795
 796         print_time_passes_entry(
 797             "codegen_to_LLVM_IR",
 798             total_codegen_time,
 799             start_rss.unwrap(),
 800             end_rss,
 801             tcx.sess.opts.unstable_opts.time_passes_format,
 802         );
 803     }
 804
 805     ongoing_codegen.check_for_errors(tcx.sess);
 806     ongoing_codegen
 807 }
 808
 809 impl CrateInfo {
 810     pub fn new(tcx: TyCtxt<'_>, target_cpu: String) -> CrateInfo {
 811         let crate_types = tcx.crate_types().to_vec();
 812         let exported_symbols = crate_types
 813             .iter()
 814             .map(|&c| (c, crate::back::linker::exported_symbols(tcx, c)))
 815             .collect();
 816         let linked_symbols =
 817             crate_types.iter().map(|&c| (c, crate::back::linker::linked_symbols(tcx, c))).collect();
 818         let local_crate_name = tcx.crate_name(LOCAL_CRATE);
 819         let crate_attrs = tcx.hir().attrs(rustc_hir::CRATE_HIR_ID);
 820         let subsystem = attr::first_attr_value_str_by_name(crate_attrs, sym::windows_subsystem);
 821         let windows_subsystem = subsystem.map(|subsystem| {
 822             if subsystem != sym::windows && subsystem != sym::console {
 823                 tcx.dcx().emit_fatal(errors::InvalidWindowsSubsystem { subsystem });
 824             }
 825             subsystem.to_string()
 826         });
 827
 828         // This list is used when generating the command line to pass through to
 829         // system linker. The linker expects undefined symbols on the left of the
 830         // command line to be defined in libraries on the right, not the other way
 831         // around. For more info, see some comments in the add_used_library function
 832         // below.
 833         //
 834         // In order to get this left-to-right dependency ordering, we use the reverse
 835         // postorder of all crates putting the leaves at the right-most positions.
 836         let mut compiler_builtins = None;
 837         let mut used_crates: Vec<_> = tcx
 838             .postorder_cnums(())
 839             .iter()
 840             .rev()
 841             .copied()
 842             .filter(|&cnum| {
 843                 let link = !tcx.dep_kind(cnum).macros_only();
 844                 if link && tcx.is_compiler_builtins(cnum) {
 845                     compiler_builtins = Some(cnum);
 846                     return false;
 847                 }
 848                 link
 849             })
 850             .collect();
 851         // `compiler_builtins` are always placed last to ensure that they're linked correctly.
 852         used_crates.extend(compiler_builtins);
 853
 854         let mut info = CrateInfo {
 855             target_cpu,
 856             crate_types,
 857             exported_symbols,
 858             linked_symbols,
 859             local_crate_name,
 860             compiler_builtins,
 861             profiler_runtime: None,
 862             is_no_builtins: Default::default(),
 863             native_libraries: Default::default(),
 864             used_libraries: tcx.native_libraries(LOCAL_CRATE).iter().map(Into::into).collect(),
 865             crate_name: Default::default(),
 866             used_crates,
 867             used_crate_source: Default::default(),
 868             dependency_formats: tcx.dependency_formats(()).clone(),
 869             windows_subsystem,
 870             natvis_debugger_visualizers: Default::default(),
 871         };
 872         let crates = tcx.crates(());
 873
 874         let n_crates = crates.len();
 875         info.native_libraries.reserve(n_crates);
 876         info.crate_name.reserve(n_crates);
 877         info.used_crate_source.reserve(n_crates);
 878
 879         for &cnum in crates.iter() {
 880             info.native_libraries
 881                 .insert(cnum, tcx.native_libraries(cnum).iter().map(Into::into).collect());
 882             info.crate_name.insert(cnum, tcx.crate_name(cnum));
 883
 884             let used_crate_source = tcx.used_crate_source(cnum);
 885             info.used_crate_source.insert(cnum, used_crate_source.clone());
 886             if tcx.is_profiler_runtime(cnum) {
 887                 info.profiler_runtime = Some(cnum);
 888             }
 889             if tcx.is_no_builtins(cnum) {
 890                 info.is_no_builtins.insert(cnum);
 891             }
 892         }
 893
 894         // Handle circular dependencies in the standard library.
 895         // See comment before `add_linked_symbol_object` function for the details.
 896         // If global LTO is enabled then almost everything (*) is glued into a single object file,
 897         // so this logic is not necessary and can cause issues on some targets (due to weak lang
 898         // item symbols being "privatized" to that object file), so we disable it.
 899         // (*) Native libs, and `#[compiler_builtins]` and `#[no_builtins]` crates are not glued,
 900         // and we assume that they cannot define weak lang items. This is not currently enforced
 901         // by the compiler, but that's ok because all this stuff is unstable anyway.
 902         let target = &tcx.sess.target;
 903         if !are_upstream_rust_objects_already_included(tcx.sess) {
 904             let missing_weak_lang_items: FxHashSet<Symbol> = info
 905                 .used_crates
 906                 .iter()
 907                 .flat_map(|&cnum| tcx.missing_lang_items(cnum))
 908                 .filter(|l| l.is_weak())
 909                 .filter_map(|&l| {
 910                     let name = l.link_name()?;
 911                     lang_items::required(tcx, l).then_some(name)
 912                 })
 913                 .collect();
 914             let prefix = if target.is_like_windows && target.arch == "x86" { "_" } else { "" };
 915
 916             // This loop only adds new items to values of the hash map, so the order in which we
 917             // iterate over the values is not important.
 918             #[allow(rustc::potential_query_instability)]
 919             info.linked_symbols
 920                 .iter_mut()
 921                 .filter(|(crate_type, _)| {
 922                     !matches!(crate_type, CrateType::Rlib | CrateType::Staticlib)
 923                 })
 924                 .for_each(|(_, linked_symbols)| {
 925                     let mut symbols = missing_weak_lang_items
 926                         .iter()
 927                         .map(|item| (format!("{prefix}{item}"), SymbolExportKind::Text))
 928                         .collect::<Vec<_>>();
 929                     symbols.sort_unstable_by(|a, b| a.0.cmp(&b.0));
 930                     linked_symbols.extend(symbols);
 931                     if tcx.allocator_kind(()).is_some() {
 932                         // At least one crate needs a global allocator. This crate may be placed
 933                         // after the crate that defines it in the linker order, in which case some
 934                         // linkers return an error. By adding the global allocator shim methods to
 935                         // the linked_symbols list, linking the generated symbols.o will ensure that
 936                         // circular dependencies involving the global allocator don't lead to linker
 937                         // errors.
 938                         linked_symbols.extend(ALLOCATOR_METHODS.iter().map(|method| {
 939                             (
 940                                 format!("{prefix}{}", global_fn_name(method.name).as_str()),
 941                                 SymbolExportKind::Text,
 942                             )
 943                         }));
 944                     }
 945                 });
 946         }
 947
 948         let embed_visualizers = tcx.crate_types().iter().any(|&crate_type| match crate_type {
 949             CrateType::Executable | CrateType::Dylib | CrateType::Cdylib => {
 950                 // These are crate types for which we invoke the linker and can embed
 951                 // NatVis visualizers.
 952                 true
 953             }
 954             CrateType::ProcMacro => {
 955                 // We could embed NatVis for proc macro crates too (to improve the debugging
 956                 // experience for them) but it does not seem like a good default, since
 957                 // this is a rare use case and we don't want to slow down the common case.
 958                 false
 959             }
 960             CrateType::Staticlib | CrateType::Rlib => {
 961                 // We don't invoke the linker for these, so we don't need to collect the NatVis for them.
 962                 false
 963             }
 964         });
 965
 966         if target.is_like_msvc && embed_visualizers {
 967             info.natvis_debugger_visualizers =
 968                 collect_debugger_visualizers_transitive(tcx, DebuggerVisualizerType::Natvis);
 969         }
 970
 971         info
 972     }
 973 }
 974
 975 pub fn provide(providers: &mut Providers) {
 976     providers.backend_optimization_level = |tcx, cratenum| {
 977         let for_speed = match tcx.sess.opts.optimize {
 978             // If globally no optimisation is done, #[optimize] has no effect.
 979             //
 980             // This is done because if we ended up "upgrading" to `-O2` here, we’d populate the
 981             // pass manager and it is likely that some module-wide passes (such as inliner or
 982             // cross-function constant propagation) would ignore the `optnone` annotation we put
 983             // on the functions, thus necessarily involving these functions into optimisations.
 984             config::OptLevel::No => return config::OptLevel::No,
 985             // If globally optimise-speed is already specified, just use that level.
 986             config::OptLevel::Less => return config::OptLevel::Less,
 987             config::OptLevel::Default => return config::OptLevel::Default,
 988             config::OptLevel::Aggressive => return config::OptLevel::Aggressive,
 989             // If globally optimize-for-size has been requested, use -O2 instead (if optimize(size)
 990             // are present).
 991             config::OptLevel::Size => config::OptLevel::Default,
 992             config::OptLevel::SizeMin => config::OptLevel::Default,
 993         };
 994
 995         let (defids, _) = tcx.collect_and_partition_mono_items(cratenum);
 996
 997         let any_for_speed = defids.items().any(|id| {
 998             let CodegenFnAttrs { optimize, .. } = tcx.codegen_fn_attrs(*id);
 999             match optimize {
1000                 attr::OptimizeAttr::None | attr::OptimizeAttr::Size => false,
1001                 attr::OptimizeAttr::Speed => true,
1002             }
1003         });
1004
1005         if any_for_speed {
1006             return for_speed;
1007         }
1008
1009         tcx.sess.opts.optimize
1010     };
1011 }
1012
1013 pub fn determine_cgu_reuse<'tcx>(tcx: TyCtxt<'tcx>, cgu: &CodegenUnit<'tcx>) -> CguReuse {
1014     if !tcx.dep_graph.is_fully_enabled() {
1015         return CguReuse::No;
1016     }
1017
1018     let work_product_id = &cgu.work_product_id();
1019     if tcx.dep_graph.previous_work_product(work_product_id).is_none() {
1020         // We don't have anything cached for this CGU. This can happen
1021         // if the CGU did not exist in the previous session.
1022         return CguReuse::No;
1023     }
1024
1025     // Try to mark the CGU as green. If it we can do so, it means that nothing
1026     // affecting the LLVM module has changed and we can re-use a cached version.
1027     // If we compile with any kind of LTO, this means we can re-use the bitcode
1028     // of the Pre-LTO stage (possibly also the Post-LTO version but we'll only
1029     // know that later). If we are not doing LTO, there is only one optimized
1030     // version of each module, so we re-use that.
1031     let dep_node = cgu.codegen_dep_node(tcx);
1032     assert!(
1033         !tcx.dep_graph.dep_node_exists(&dep_node),
1034         "CompileCodegenUnit dep-node for CGU `{}` already exists before marking.",
1035         cgu.name()
1036     );
1037
1038     if tcx.try_mark_green(&dep_node) {
1039         // We can re-use either the pre- or the post-thinlto state. If no LTO is
1040         // being performed then we can use post-LTO artifacts, otherwise we must
1041         // reuse pre-LTO artifacts
1042         match compute_per_cgu_lto_type(
1043             &tcx.sess.lto(),
1044             &tcx.sess.opts,
1045             tcx.crate_types(),
1046             ModuleKind::Regular,
1047         ) {
1048             ComputedLtoType::No => CguReuse::PostLto,
1049             _ => CguReuse::PreLto,
1050         }
1051     } else {
1052         CguReuse::No
1053     }
1054 }