use crate::assert_module_sources::CguReuse; use crate::back::link::are_upstream_rust_objects_already_included; use crate::back::metadata::create_compressed_metadata_file; use crate::back::write::{ compute_per_cgu_lto_type, start_async_codegen, submit_codegened_module_to_llvm, submit_post_lto_module_to_llvm, submit_pre_lto_module_to_llvm, ComputedLtoType, OngoingCodegen, }; use crate::common::{IntPredicate, RealPredicate, TypeKind}; use crate::errors; use crate::meth; use crate::mir; use crate::mir::operand::OperandValue; use crate::mir::place::PlaceRef; use crate::traits::*; use crate::{CachedModuleCodegen, CompiledModule, CrateInfo, MemFlags, ModuleCodegen, ModuleKind}; use rustc_ast::expand::allocator::{global_fn_name, AllocatorKind, ALLOCATOR_METHODS}; use rustc_attr as attr; use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_data_structures::profiling::{get_resident_set_size, print_time_passes_entry}; use rustc_data_structures::sync::par_map; use rustc_hir as hir; use rustc_hir::def_id::{DefId, LOCAL_CRATE}; use rustc_hir::lang_items::LangItem; use rustc_metadata::EncodedMetadata; use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs; use rustc_middle::middle::debugger_visualizer::{DebuggerVisualizerFile, DebuggerVisualizerType}; use rustc_middle::middle::exported_symbols; use rustc_middle::middle::exported_symbols::SymbolExportKind; use rustc_middle::middle::lang_items; use rustc_middle::mir::mono::{CodegenUnit, CodegenUnitNameBuilder, MonoItem}; use rustc_middle::query::Providers; use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, TyAndLayout}; use rustc_middle::ty::{self, Instance, Ty, TyCtxt}; use rustc_session::config::{self, CrateType, EntryFnType, OutputType}; use rustc_session::Session; use rustc_span::symbol::sym; use rustc_span::Symbol; use rustc_target::abi::{Align, FIRST_VARIANT}; use std::cmp; use std::collections::BTreeSet; use std::time::{Duration, Instant}; use itertools::Itertools; pub fn bin_op_to_icmp_predicate(op: hir::BinOpKind, signed: bool) -> IntPredicate { match op { hir::BinOpKind::Eq => IntPredicate::IntEQ, hir::BinOpKind::Ne => IntPredicate::IntNE, hir::BinOpKind::Lt => { if signed { IntPredicate::IntSLT } else { IntPredicate::IntULT } } hir::BinOpKind::Le => { if signed { IntPredicate::IntSLE } else { IntPredicate::IntULE } } hir::BinOpKind::Gt => { if signed { IntPredicate::IntSGT } else { IntPredicate::IntUGT } } hir::BinOpKind::Ge => { if signed { IntPredicate::IntSGE } else { IntPredicate::IntUGE } } op => bug!( "comparison_op_to_icmp_predicate: expected comparison operator, \ found {:?}", op ), } } pub fn bin_op_to_fcmp_predicate(op: hir::BinOpKind) -> RealPredicate { match op { hir::BinOpKind::Eq => RealPredicate::RealOEQ, hir::BinOpKind::Ne => RealPredicate::RealUNE, hir::BinOpKind::Lt => RealPredicate::RealOLT, hir::BinOpKind::Le => RealPredicate::RealOLE, hir::BinOpKind::Gt => RealPredicate::RealOGT, hir::BinOpKind::Ge => RealPredicate::RealOGE, op => { bug!( "comparison_op_to_fcmp_predicate: expected comparison operator, \ found {:?}", op ); } } } pub fn compare_simd_types<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( bx: &mut Bx, lhs: Bx::Value, rhs: Bx::Value, t: Ty<'tcx>, ret_ty: Bx::Type, op: hir::BinOpKind, ) -> Bx::Value { let signed = match t.kind() { ty::Float(_) => { let cmp = bin_op_to_fcmp_predicate(op); let cmp = bx.fcmp(cmp, lhs, rhs); return bx.sext(cmp, ret_ty); } ty::Uint(_) => false, ty::Int(_) => true, _ => bug!("compare_simd_types: invalid SIMD type"), }; let cmp = bin_op_to_icmp_predicate(op, signed); let cmp = bx.icmp(cmp, lhs, rhs); // LLVM outputs an `< size x i1 >`, so we need to perform a sign extension // to get the correctly sized type. This will compile to a single instruction // once the IR is converted to assembly if the SIMD instruction is supported // by the target architecture. bx.sext(cmp, ret_ty) } /// Retrieves the information we are losing (making dynamic) in an unsizing /// adjustment. /// /// The `old_info` argument is a bit odd. It is intended for use in an upcast, /// where the new vtable for an object will be derived from the old one. pub fn unsized_info<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( bx: &mut Bx, source: Ty<'tcx>, target: Ty<'tcx>, old_info: Option, ) -> Bx::Value { let cx = bx.cx(); let (source, target) = cx.tcx().struct_lockstep_tails_erasing_lifetimes(source, target, bx.param_env()); match (source.kind(), target.kind()) { (&ty::Array(_, len), &ty::Slice(_)) => { cx.const_usize(len.eval_target_usize(cx.tcx(), ty::ParamEnv::reveal_all())) } (&ty::Dynamic(data_a, _, src_dyn_kind), &ty::Dynamic(data_b, _, target_dyn_kind)) if src_dyn_kind == target_dyn_kind => { let old_info = old_info.expect("unsized_info: missing old info for trait upcasting coercion"); if data_a.principal_def_id() == data_b.principal_def_id() { // A NOP cast that doesn't actually change anything, should be allowed even with invalid vtables. return old_info; } // trait upcasting coercion let vptr_entry_idx = cx.tcx().vtable_trait_upcasting_coercion_new_vptr_slot((source, target)); if let Some(entry_idx) = vptr_entry_idx { let ptr_ty = cx.type_ptr(); let ptr_align = cx.tcx().data_layout.pointer_align.abi; let gep = bx.inbounds_gep( ptr_ty, old_info, &[bx.const_usize(u64::try_from(entry_idx).unwrap())], ); let new_vptr = bx.load(ptr_ty, gep, ptr_align); bx.nonnull_metadata(new_vptr); // VTable loads are invariant. bx.set_invariant_load(new_vptr); new_vptr } else { old_info } } (_, ty::Dynamic(data, _, _)) => meth::get_vtable(cx, source, data.principal()), _ => bug!("unsized_info: invalid unsizing {:?} -> {:?}", source, target), } } /// Coerces `src` to `dst_ty`. `src_ty` must be a pointer. pub fn unsize_ptr<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( bx: &mut Bx, src: Bx::Value, src_ty: Ty<'tcx>, dst_ty: Ty<'tcx>, old_info: Option, ) -> (Bx::Value, Bx::Value) { debug!("unsize_ptr: {:?} => {:?}", src_ty, dst_ty); match (src_ty.kind(), dst_ty.kind()) { (&ty::Ref(_, a, _), &ty::Ref(_, b, _) | &ty::RawPtr(ty::TypeAndMut { ty: b, .. })) | (&ty::RawPtr(ty::TypeAndMut { ty: a, .. }), &ty::RawPtr(ty::TypeAndMut { ty: b, .. })) => { assert_eq!(bx.cx().type_is_sized(a), old_info.is_none()); (src, unsized_info(bx, a, b, old_info)) } (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => { assert_eq!(def_a, def_b); // implies same number of fields let src_layout = bx.cx().layout_of(src_ty); let dst_layout = bx.cx().layout_of(dst_ty); if src_ty == dst_ty { return (src, old_info.unwrap()); } let mut result = None; for i in 0..src_layout.fields.count() { let src_f = src_layout.field(bx.cx(), i); if src_f.is_1zst() { // We are looking for the one non-1-ZST field; this is not it. continue; } assert_eq!(src_layout.fields.offset(i).bytes(), 0); assert_eq!(dst_layout.fields.offset(i).bytes(), 0); assert_eq!(src_layout.size, src_f.size); let dst_f = dst_layout.field(bx.cx(), i); assert_ne!(src_f.ty, dst_f.ty); assert_eq!(result, None); result = Some(unsize_ptr(bx, src, src_f.ty, dst_f.ty, old_info)); } result.unwrap() } _ => bug!("unsize_ptr: called on bad types"), } } /// Coerces `src` to `dst_ty` which is guaranteed to be a `dyn*` type. pub fn cast_to_dyn_star<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( bx: &mut Bx, src: Bx::Value, src_ty_and_layout: TyAndLayout<'tcx>, dst_ty: Ty<'tcx>, old_info: Option, ) -> (Bx::Value, Bx::Value) { debug!("cast_to_dyn_star: {:?} => {:?}", src_ty_and_layout.ty, dst_ty); assert!( matches!(dst_ty.kind(), ty::Dynamic(_, _, ty::DynStar)), "destination type must be a dyn*" ); let src = match bx.cx().type_kind(bx.cx().backend_type(src_ty_and_layout)) { TypeKind::Pointer => src, TypeKind::Integer => bx.inttoptr(src, bx.type_ptr()), // FIXME(dyn-star): We probably have to do a bitcast first, then inttoptr. kind => bug!("unexpected TypeKind for left-hand side of `dyn*` cast: {kind:?}"), }; (src, unsized_info(bx, src_ty_and_layout.ty, dst_ty, old_info)) } /// Coerces `src`, which is a reference to a value of type `src_ty`, /// to a value of type `dst_ty`, and stores the result in `dst`. pub fn coerce_unsized_into<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( bx: &mut Bx, src: PlaceRef<'tcx, Bx::Value>, dst: PlaceRef<'tcx, Bx::Value>, ) { let src_ty = src.layout.ty; let dst_ty = dst.layout.ty; match (src_ty.kind(), dst_ty.kind()) { (&ty::Ref(..), &ty::Ref(..) | &ty::RawPtr(..)) | (&ty::RawPtr(..), &ty::RawPtr(..)) => { let (base, info) = match bx.load_operand(src).val { OperandValue::Pair(base, info) => unsize_ptr(bx, base, src_ty, dst_ty, Some(info)), OperandValue::Immediate(base) => unsize_ptr(bx, base, src_ty, dst_ty, None), OperandValue::Ref(..) | OperandValue::ZeroSized => bug!(), }; OperandValue::Pair(base, info).store(bx, dst); } (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => { assert_eq!(def_a, def_b); // implies same number of fields for i in def_a.variant(FIRST_VARIANT).fields.indices() { let src_f = src.project_field(bx, i.as_usize()); let dst_f = dst.project_field(bx, i.as_usize()); if dst_f.layout.is_zst() { // No data here, nothing to copy/coerce. continue; } if src_f.layout.ty == dst_f.layout.ty { memcpy_ty( bx, dst_f.llval, dst_f.align, src_f.llval, src_f.align, src_f.layout, MemFlags::empty(), ); } else { coerce_unsized_into(bx, src_f, dst_f); } } } _ => bug!("coerce_unsized_into: invalid coercion {:?} -> {:?}", src_ty, dst_ty,), } } pub fn cast_shift_expr_rhs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( bx: &mut Bx, lhs: Bx::Value, rhs: Bx::Value, ) -> Bx::Value { // Shifts may have any size int on the rhs let mut rhs_llty = bx.cx().val_ty(rhs); let mut lhs_llty = bx.cx().val_ty(lhs); if bx.cx().type_kind(rhs_llty) == TypeKind::Vector { rhs_llty = bx.cx().element_type(rhs_llty) } if bx.cx().type_kind(lhs_llty) == TypeKind::Vector { lhs_llty = bx.cx().element_type(lhs_llty) } let rhs_sz = bx.cx().int_width(rhs_llty); let lhs_sz = bx.cx().int_width(lhs_llty); if lhs_sz < rhs_sz { bx.trunc(rhs, lhs_llty) } else if lhs_sz > rhs_sz { // We zero-extend even if the RHS is signed. So e.g. `(x: i32) << -1i8` will zero-extend the // RHS to `255i32`. But then we mask the shift amount to be within the size of the LHS // anyway so the result is `31` as it should be. All the extra bits introduced by zext // are masked off so their value does not matter. // FIXME: if we ever support 512bit integers, this will be wrong! For such large integers, // the extra bits introduced by zext are *not* all masked away any more. assert!(lhs_sz <= 256); bx.zext(rhs, lhs_llty) } else { rhs } } // Returns `true` if this session's target will use native wasm // exceptions. This means that the VM does the unwinding for // us pub fn wants_wasm_eh(sess: &Session) -> bool { sess.target.is_like_wasm && sess.target.os != "emscripten" } /// Returns `true` if this session's target will use SEH-based unwinding. /// /// This is only true for MSVC targets, and even then the 64-bit MSVC target /// currently uses SEH-ish unwinding with DWARF info tables to the side (same as /// 64-bit MinGW) instead of "full SEH". pub fn wants_msvc_seh(sess: &Session) -> bool { sess.target.is_like_msvc } /// Returns `true` if this session's target requires the new exception /// handling LLVM IR instructions (catchpad / cleanuppad / ... instead /// of landingpad) pub fn wants_new_eh_instructions(sess: &Session) -> bool { wants_wasm_eh(sess) || wants_msvc_seh(sess) } pub fn memcpy_ty<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( bx: &mut Bx, dst: Bx::Value, dst_align: Align, src: Bx::Value, src_align: Align, layout: TyAndLayout<'tcx>, flags: MemFlags, ) { let size = layout.size.bytes(); if size == 0 { return; } if flags == MemFlags::empty() && let Some(bty) = bx.cx().scalar_copy_backend_type(layout) { let temp = bx.load(bty, src, src_align); bx.store(temp, dst, dst_align); } else { bx.memcpy(dst, dst_align, src, src_align, bx.cx().const_usize(size), flags); } } pub fn codegen_instance<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>( cx: &'a Bx::CodegenCx, instance: Instance<'tcx>, ) { // this is an info! to allow collecting monomorphization statistics // and to allow finding the last function before LLVM aborts from // release builds. info!("codegen_instance({})", instance); mir::codegen_mir::(cx, instance); } /// Creates the `main` function which will initialize the rust runtime and call /// users main function. pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( cx: &'a Bx::CodegenCx, ) -> Option { let (main_def_id, entry_type) = cx.tcx().entry_fn(())?; let main_is_local = main_def_id.is_local(); let instance = Instance::mono(cx.tcx(), main_def_id); if main_is_local { // We want to create the wrapper in the same codegen unit as Rust's main // function. if !cx.codegen_unit().contains_item(&MonoItem::Fn(instance)) { return None; } } else if !cx.codegen_unit().is_primary() { // We want to create the wrapper only when the codegen unit is the primary one return None; } let main_llfn = cx.get_fn_addr(instance); let entry_fn = create_entry_fn::(cx, main_llfn, main_def_id, entry_type); return Some(entry_fn); fn create_entry_fn<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( cx: &'a Bx::CodegenCx, rust_main: Bx::Value, rust_main_def_id: DefId, entry_type: EntryFnType, ) -> Bx::Function { // The entry function is either `int main(void)` or `int main(int argc, char **argv)`, or // `usize efi_main(void *handle, void *system_table)` depending on the target. let llfty = if cx.sess().target.os.contains("uefi") { cx.type_func(&[cx.type_ptr(), cx.type_ptr()], cx.type_isize()) } else if cx.sess().target.main_needs_argc_argv { cx.type_func(&[cx.type_int(), cx.type_ptr()], cx.type_int()) } else { cx.type_func(&[], cx.type_int()) }; let main_ret_ty = cx.tcx().fn_sig(rust_main_def_id).no_bound_vars().unwrap().output(); // Given that `main()` has no arguments, // then its return type cannot have // late-bound regions, since late-bound // regions must appear in the argument // listing. let main_ret_ty = cx.tcx().normalize_erasing_regions( ty::ParamEnv::reveal_all(), main_ret_ty.no_bound_vars().unwrap(), ); let Some(llfn) = cx.declare_c_main(llfty) else { // FIXME: We should be smart and show a better diagnostic here. let span = cx.tcx().def_span(rust_main_def_id); cx.sess().emit_err(errors::MultipleMainFunctions { span }); cx.sess().abort_if_errors(); bug!(); }; // `main` should respect same config for frame pointer elimination as rest of code cx.set_frame_pointer_type(llfn); cx.apply_target_cpu_attr(llfn); let llbb = Bx::append_block(cx, llfn, "top"); let mut bx = Bx::build(cx, llbb); bx.insert_reference_to_gdb_debug_scripts_section_global(); let isize_ty = cx.type_isize(); let ptr_ty = cx.type_ptr(); let (arg_argc, arg_argv) = get_argc_argv(cx, &mut bx); let (start_fn, start_ty, args) = if let EntryFnType::Main { sigpipe } = entry_type { let start_def_id = cx.tcx().require_lang_item(LangItem::Start, None); let start_fn = cx.get_fn_addr( ty::Instance::resolve( cx.tcx(), ty::ParamEnv::reveal_all(), start_def_id, cx.tcx().mk_args(&[main_ret_ty.into()]), ) .unwrap() .unwrap(), ); let i8_ty = cx.type_i8(); let arg_sigpipe = bx.const_u8(sigpipe); let start_ty = cx.type_func(&[cx.val_ty(rust_main), isize_ty, ptr_ty, i8_ty], isize_ty); (start_fn, start_ty, vec![rust_main, arg_argc, arg_argv, arg_sigpipe]) } else { debug!("using user-defined start fn"); let start_ty = cx.type_func(&[isize_ty, ptr_ty], isize_ty); (rust_main, start_ty, vec![arg_argc, arg_argv]) }; let result = bx.call(start_ty, None, None, start_fn, &args, None); if cx.sess().target.os.contains("uefi") { bx.ret(result); } else { let cast = bx.intcast(result, cx.type_int(), true); bx.ret(cast); } llfn } } /// Obtain the `argc` and `argv` values to pass to the rust start function. fn get_argc_argv<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( cx: &'a Bx::CodegenCx, bx: &mut Bx, ) -> (Bx::Value, Bx::Value) { if cx.sess().target.os.contains("uefi") { // Params for UEFI let param_handle = bx.get_param(0); let param_system_table = bx.get_param(1); let arg_argc = bx.const_int(cx.type_isize(), 2); let arg_argv = bx.alloca(cx.type_array(cx.type_ptr(), 2), Align::ONE); bx.store(param_handle, arg_argv, Align::ONE); let arg_argv_el1 = bx.gep(cx.type_ptr(), arg_argv, &[bx.const_int(cx.type_int(), 1)]); bx.store(param_system_table, arg_argv_el1, Align::ONE); (arg_argc, arg_argv) } else if cx.sess().target.main_needs_argc_argv { // Params from native `main()` used as args for rust start function let param_argc = bx.get_param(0); let param_argv = bx.get_param(1); let arg_argc = bx.intcast(param_argc, cx.type_isize(), true); let arg_argv = param_argv; (arg_argc, arg_argv) } else { // The Rust start function doesn't need `argc` and `argv`, so just pass zeros. let arg_argc = bx.const_int(cx.type_int(), 0); let arg_argv = bx.const_null(cx.type_ptr()); (arg_argc, arg_argv) } } /// This function returns all of the debugger visualizers specified for the /// current crate as well as all upstream crates transitively that match the /// `visualizer_type` specified. pub fn collect_debugger_visualizers_transitive( tcx: TyCtxt<'_>, visualizer_type: DebuggerVisualizerType, ) -> BTreeSet { tcx.debugger_visualizers(LOCAL_CRATE) .iter() .chain( tcx.crates(()) .iter() .filter(|&cnum| { let used_crate_source = tcx.used_crate_source(*cnum); used_crate_source.rlib.is_some() || used_crate_source.rmeta.is_some() }) .flat_map(|&cnum| tcx.debugger_visualizers(cnum)), ) .filter(|visualizer| visualizer.visualizer_type == visualizer_type) .cloned() .collect::>() } /// Decide allocator kind to codegen. If `Some(_)` this will be the same as /// `tcx.allocator_kind`, but it may be `None` in more cases (e.g. if using /// allocator definitions from a dylib dependency). pub fn allocator_kind_for_codegen(tcx: TyCtxt<'_>) -> Option { // If the crate doesn't have an `allocator_kind` set then there's definitely // no shim to generate. Otherwise we also check our dependency graph for all // our output crate types. If anything there looks like its a `Dynamic` // linkage, then it's already got an allocator shim and we'll be using that // one instead. If nothing exists then it's our job to generate the // allocator! let any_dynamic_crate = tcx.dependency_formats(()).iter().any(|(_, list)| { use rustc_middle::middle::dependency_format::Linkage; list.iter().any(|&linkage| linkage == Linkage::Dynamic) }); if any_dynamic_crate { None } else { tcx.allocator_kind(()) } } pub fn codegen_crate( backend: B, tcx: TyCtxt<'_>, target_cpu: String, metadata: EncodedMetadata, need_metadata_module: bool, ) -> OngoingCodegen { // Skip crate items and just output metadata in -Z no-codegen mode. if tcx.sess.opts.unstable_opts.no_codegen || !tcx.sess.opts.output_types.should_codegen() { let ongoing_codegen = start_async_codegen(backend, tcx, target_cpu, metadata, None); ongoing_codegen.codegen_finished(tcx); ongoing_codegen.check_for_errors(tcx.sess); return ongoing_codegen; } let cgu_name_builder = &mut CodegenUnitNameBuilder::new(tcx); // Run the monomorphization collector and partition the collected items into // codegen units. let codegen_units = tcx.collect_and_partition_mono_items(()).1; // Force all codegen_unit queries so they are already either red or green // when compile_codegen_unit accesses them. We are not able to re-execute // the codegen_unit query from just the DepNode, so an unknown color would // lead to having to re-execute compile_codegen_unit, possibly // unnecessarily. if tcx.dep_graph.is_fully_enabled() { for cgu in codegen_units { tcx.ensure().codegen_unit(cgu.name()); } } let metadata_module = need_metadata_module.then(|| { // Emit compressed metadata object. let metadata_cgu_name = cgu_name_builder.build_cgu_name(LOCAL_CRATE, &["crate"], Some("metadata")).to_string(); tcx.sess.time("write_compressed_metadata", || { let file_name = tcx.output_filenames(()).temp_path(OutputType::Metadata, Some(&metadata_cgu_name)); let data = create_compressed_metadata_file( tcx.sess, &metadata, &exported_symbols::metadata_symbol_name(tcx), ); if let Err(error) = std::fs::write(&file_name, data) { tcx.sess.emit_fatal(errors::MetadataObjectFileWrite { error }); } CompiledModule { name: metadata_cgu_name, kind: ModuleKind::Metadata, object: Some(file_name), dwarf_object: None, bytecode: None, } }) }); let ongoing_codegen = start_async_codegen(backend.clone(), tcx, target_cpu, metadata, metadata_module); // Codegen an allocator shim, if necessary. if let Some(kind) = allocator_kind_for_codegen(tcx) { let llmod_id = cgu_name_builder.build_cgu_name(LOCAL_CRATE, &["crate"], Some("allocator")).to_string(); let module_llvm = tcx.sess.time("write_allocator_module", || { backend.codegen_allocator( tcx, &llmod_id, kind, // If allocator_kind is Some then alloc_error_handler_kind must // also be Some. tcx.alloc_error_handler_kind(()).unwrap(), ) }); ongoing_codegen.wait_for_signal_to_codegen_item(); ongoing_codegen.check_for_errors(tcx.sess); // These modules are generally cheap and won't throw off scheduling. let cost = 0; submit_codegened_module_to_llvm( &backend, &ongoing_codegen.coordinator.sender, ModuleCodegen { name: llmod_id, module_llvm, kind: ModuleKind::Allocator }, cost, ); } // For better throughput during parallel processing by LLVM, we used to sort // CGUs largest to smallest. This would lead to better thread utilization // by, for example, preventing a large CGU from being processed last and // having only one LLVM thread working while the rest remained idle. // // However, this strategy would lead to high memory usage, as it meant the // LLVM-IR for all of the largest CGUs would be resident in memory at once. // // Instead, we can compromise by ordering CGUs such that the largest and // smallest are first, second largest and smallest are next, etc. If there // are large size variations, this can reduce memory usage significantly. let codegen_units: Vec<_> = { let mut sorted_cgus = codegen_units.iter().collect::>(); sorted_cgus.sort_by_key(|cgu| cmp::Reverse(cgu.size_estimate())); let (first_half, second_half) = sorted_cgus.split_at(sorted_cgus.len() / 2); first_half.iter().interleave(second_half.iter().rev()).copied().collect() }; // Calculate the CGU reuse let cgu_reuse = tcx.sess.time("find_cgu_reuse", || { codegen_units.iter().map(|cgu| determine_cgu_reuse(tcx, cgu)).collect::>() }); crate::assert_module_sources::assert_module_sources(tcx, &|cgu_reuse_tracker| { for (i, cgu) in codegen_units.iter().enumerate() { let cgu_reuse = cgu_reuse[i]; cgu_reuse_tracker.set_actual_reuse(cgu.name().as_str(), cgu_reuse); } }); let mut total_codegen_time = Duration::new(0, 0); let start_rss = tcx.sess.opts.unstable_opts.time_passes.then(|| get_resident_set_size()); // The non-parallel compiler can only translate codegen units to LLVM IR // on a single thread, leading to a staircase effect where the N LLVM // threads have to wait on the single codegen threads to generate work // for them. The parallel compiler does not have this restriction, so // we can pre-load the LLVM queue in parallel before handing off // coordination to the OnGoingCodegen scheduler. // // This likely is a temporary measure. Once we don't have to support the // non-parallel compiler anymore, we can compile CGUs end-to-end in // parallel and get rid of the complicated scheduling logic. let mut pre_compiled_cgus = if tcx.sess.threads() > 1 { tcx.sess.time("compile_first_CGU_batch", || { // Try to find one CGU to compile per thread. let cgus: Vec<_> = cgu_reuse .iter() .enumerate() .filter(|&(_, reuse)| reuse == &CguReuse::No) .take(tcx.sess.threads()) .collect(); // Compile the found CGUs in parallel. let start_time = Instant::now(); let pre_compiled_cgus = par_map(cgus, |(i, _)| { let module = backend.compile_codegen_unit(tcx, codegen_units[i].name()); (i, module) }); total_codegen_time += start_time.elapsed(); pre_compiled_cgus }) } else { FxHashMap::default() }; for (i, cgu) in codegen_units.iter().enumerate() { ongoing_codegen.wait_for_signal_to_codegen_item(); ongoing_codegen.check_for_errors(tcx.sess); let cgu_reuse = cgu_reuse[i]; match cgu_reuse { CguReuse::No => { let (module, cost) = if let Some(cgu) = pre_compiled_cgus.remove(&i) { cgu } else { let start_time = Instant::now(); let module = backend.compile_codegen_unit(tcx, cgu.name()); total_codegen_time += start_time.elapsed(); module }; // This will unwind if there are errors, which triggers our `AbortCodegenOnDrop` // guard. Unfortunately, just skipping the `submit_codegened_module_to_llvm` makes // compilation hang on post-monomorphization errors. tcx.sess.abort_if_errors(); submit_codegened_module_to_llvm( &backend, &ongoing_codegen.coordinator.sender, module, cost, ); } CguReuse::PreLto => { submit_pre_lto_module_to_llvm( &backend, tcx, &ongoing_codegen.coordinator.sender, CachedModuleCodegen { name: cgu.name().to_string(), source: cgu.previous_work_product(tcx), }, ); } CguReuse::PostLto => { submit_post_lto_module_to_llvm( &backend, &ongoing_codegen.coordinator.sender, CachedModuleCodegen { name: cgu.name().to_string(), source: cgu.previous_work_product(tcx), }, ); } } } ongoing_codegen.codegen_finished(tcx); // Since the main thread is sometimes blocked during codegen, we keep track // -Ztime-passes output manually. if tcx.sess.opts.unstable_opts.time_passes { let end_rss = get_resident_set_size(); print_time_passes_entry( "codegen_to_LLVM_IR", total_codegen_time, start_rss.unwrap(), end_rss, tcx.sess.opts.unstable_opts.time_passes_format, ); } ongoing_codegen.check_for_errors(tcx.sess); ongoing_codegen } impl CrateInfo { pub fn new(tcx: TyCtxt<'_>, target_cpu: String) -> CrateInfo { let crate_types = tcx.crate_types().to_vec(); let exported_symbols = crate_types .iter() .map(|&c| (c, crate::back::linker::exported_symbols(tcx, c))) .collect(); let linked_symbols = crate_types.iter().map(|&c| (c, crate::back::linker::linked_symbols(tcx, c))).collect(); let local_crate_name = tcx.crate_name(LOCAL_CRATE); let crate_attrs = tcx.hir().attrs(rustc_hir::CRATE_HIR_ID); let subsystem = attr::first_attr_value_str_by_name(crate_attrs, sym::windows_subsystem); let windows_subsystem = subsystem.map(|subsystem| { if subsystem != sym::windows && subsystem != sym::console { tcx.sess.emit_fatal(errors::InvalidWindowsSubsystem { subsystem }); } subsystem.to_string() }); // This list is used when generating the command line to pass through to // system linker. The linker expects undefined symbols on the left of the // command line to be defined in libraries on the right, not the other way // around. For more info, see some comments in the add_used_library function // below. // // In order to get this left-to-right dependency ordering, we use the reverse // postorder of all crates putting the leaves at the right-most positions. let mut compiler_builtins = None; let mut used_crates: Vec<_> = tcx .postorder_cnums(()) .iter() .rev() .copied() .filter(|&cnum| { let link = !tcx.dep_kind(cnum).macros_only(); if link && tcx.is_compiler_builtins(cnum) { compiler_builtins = Some(cnum); return false; } link }) .collect(); // `compiler_builtins` are always placed last to ensure that they're linked correctly. used_crates.extend(compiler_builtins); let mut info = CrateInfo { target_cpu, crate_types, exported_symbols, linked_symbols, local_crate_name, compiler_builtins, profiler_runtime: None, is_no_builtins: Default::default(), native_libraries: Default::default(), used_libraries: tcx.native_libraries(LOCAL_CRATE).iter().map(Into::into).collect(), crate_name: Default::default(), used_crates, used_crate_source: Default::default(), dependency_formats: tcx.dependency_formats(()).clone(), windows_subsystem, natvis_debugger_visualizers: Default::default(), }; let crates = tcx.crates(()); let n_crates = crates.len(); info.native_libraries.reserve(n_crates); info.crate_name.reserve(n_crates); info.used_crate_source.reserve(n_crates); for &cnum in crates.iter() { info.native_libraries .insert(cnum, tcx.native_libraries(cnum).iter().map(Into::into).collect()); info.crate_name.insert(cnum, tcx.crate_name(cnum)); let used_crate_source = tcx.used_crate_source(cnum); info.used_crate_source.insert(cnum, used_crate_source.clone()); if tcx.is_profiler_runtime(cnum) { info.profiler_runtime = Some(cnum); } if tcx.is_no_builtins(cnum) { info.is_no_builtins.insert(cnum); } } // Handle circular dependencies in the standard library. // See comment before `add_linked_symbol_object` function for the details. // If global LTO is enabled then almost everything (*) is glued into a single object file, // so this logic is not necessary and can cause issues on some targets (due to weak lang // item symbols being "privatized" to that object file), so we disable it. // (*) Native libs, and `#[compiler_builtins]` and `#[no_builtins]` crates are not glued, // and we assume that they cannot define weak lang items. This is not currently enforced // by the compiler, but that's ok because all this stuff is unstable anyway. let target = &tcx.sess.target; if !are_upstream_rust_objects_already_included(tcx.sess) { let missing_weak_lang_items: FxHashSet = info .used_crates .iter() .flat_map(|&cnum| tcx.missing_lang_items(cnum)) .filter(|l| l.is_weak()) .filter_map(|&l| { let name = l.link_name()?; lang_items::required(tcx, l).then_some(name) }) .collect(); let prefix = if target.is_like_windows && target.arch == "x86" { "_" } else { "" }; info.linked_symbols .iter_mut() .filter(|(crate_type, _)| { !matches!(crate_type, CrateType::Rlib | CrateType::Staticlib) }) .for_each(|(_, linked_symbols)| { linked_symbols.extend( missing_weak_lang_items .iter() .map(|item| (format!("{prefix}{item}"), SymbolExportKind::Text)), ); if tcx.allocator_kind(()).is_some() { // At least one crate needs a global allocator. This crate may be placed // after the crate that defines it in the linker order, in which case some // linkers return an error. By adding the global allocator shim methods to // the linked_symbols list, linking the generated symbols.o will ensure that // circular dependencies involving the global allocator don't lead to linker // errors. linked_symbols.extend(ALLOCATOR_METHODS.iter().map(|method| { ( format!("{prefix}{}", global_fn_name(method.name).as_str()), SymbolExportKind::Text, ) })); } }); } let embed_visualizers = tcx.crate_types().iter().any(|&crate_type| match crate_type { CrateType::Executable | CrateType::Dylib | CrateType::Cdylib => { // These are crate types for which we invoke the linker and can embed // NatVis visualizers. true } CrateType::ProcMacro => { // We could embed NatVis for proc macro crates too (to improve the debugging // experience for them) but it does not seem like a good default, since // this is a rare use case and we don't want to slow down the common case. false } CrateType::Staticlib | CrateType::Rlib => { // We don't invoke the linker for these, so we don't need to collect the NatVis for them. false } }); if target.is_like_msvc && embed_visualizers { info.natvis_debugger_visualizers = collect_debugger_visualizers_transitive(tcx, DebuggerVisualizerType::Natvis); } info } } pub fn provide(providers: &mut Providers) { providers.backend_optimization_level = |tcx, cratenum| { let for_speed = match tcx.sess.opts.optimize { // If globally no optimisation is done, #[optimize] has no effect. // // This is done because if we ended up "upgrading" to `-O2` here, we’d populate the // pass manager and it is likely that some module-wide passes (such as inliner or // cross-function constant propagation) would ignore the `optnone` annotation we put // on the functions, thus necessarily involving these functions into optimisations. config::OptLevel::No => return config::OptLevel::No, // If globally optimise-speed is already specified, just use that level. config::OptLevel::Less => return config::OptLevel::Less, config::OptLevel::Default => return config::OptLevel::Default, config::OptLevel::Aggressive => return config::OptLevel::Aggressive, // If globally optimize-for-size has been requested, use -O2 instead (if optimize(size) // are present). config::OptLevel::Size => config::OptLevel::Default, config::OptLevel::SizeMin => config::OptLevel::Default, }; let (defids, _) = tcx.collect_and_partition_mono_items(cratenum); let any_for_speed = defids.items().any(|id| { let CodegenFnAttrs { optimize, .. } = tcx.codegen_fn_attrs(*id); match optimize { attr::OptimizeAttr::None | attr::OptimizeAttr::Size => false, attr::OptimizeAttr::Speed => true, } }); if any_for_speed { return for_speed; } tcx.sess.opts.optimize }; } pub fn determine_cgu_reuse<'tcx>(tcx: TyCtxt<'tcx>, cgu: &CodegenUnit<'tcx>) -> CguReuse { if !tcx.dep_graph.is_fully_enabled() { return CguReuse::No; } let work_product_id = &cgu.work_product_id(); if tcx.dep_graph.previous_work_product(work_product_id).is_none() { // We don't have anything cached for this CGU. This can happen // if the CGU did not exist in the previous session. return CguReuse::No; } // Try to mark the CGU as green. If it we can do so, it means that nothing // affecting the LLVM module has changed and we can re-use a cached version. // If we compile with any kind of LTO, this means we can re-use the bitcode // of the Pre-LTO stage (possibly also the Post-LTO version but we'll only // know that later). If we are not doing LTO, there is only one optimized // version of each module, so we re-use that. let dep_node = cgu.codegen_dep_node(tcx); assert!( !tcx.dep_graph.dep_node_exists(&dep_node), "CompileCodegenUnit dep-node for CGU `{}` already exists before marking.", cgu.name() ); if tcx.try_mark_green(&dep_node) { // We can re-use either the pre- or the post-thinlto state. If no LTO is // being performed then we can use post-LTO artifacts, otherwise we must // reuse pre-LTO artifacts match compute_per_cgu_lto_type( &tcx.sess.lto(), &tcx.sess.opts, tcx.crate_types(), ModuleKind::Regular, ) { ComputedLtoType::No => CguReuse::PostLto, _ => CguReuse::PreLto, } } else { CguReuse::No } }