use rustc_arena::TypedArena;
use rustc_ast::CRATE_NODE_ID;
-use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
+use rustc_data_structures::fx::FxIndexMap;
use rustc_data_structures::memmap::Mmap;
use rustc_data_structures::temp_dir::MaybeTempDir;
use rustc_errors::{ErrorGuaranteed, Handler};
/// that are necessary for the linking. They are only present in symbol table but not actually
/// used in any sections, so the linker will therefore pick relevant rlibs for linking, but
/// unused `#[no_mangle]` or `#[used]` can still be discard by GC sections.
+///
+/// There's a few internal crates in the standard library (aka libcore and
+/// libstd) which actually have a circular dependence upon one another. This
+/// currently arises through "weak lang items" where libcore requires things
+/// like `rust_begin_unwind` but libstd ends up defining it. To get this
+/// circular dependence to work correctly we declare some of these things
+/// in this synthetic object.
fn add_linked_symbol_object(
cmd: &mut dyn Linker,
sess: &Session,
// crates.
let deps = &codegen_results.crate_info.used_crates;
- // There's a few internal crates in the standard library (aka libcore and
- // libstd) which actually have a circular dependence upon one another. This
- // currently arises through "weak lang items" where libcore requires things
- // like `rust_begin_unwind` but libstd ends up defining it. To get this
- // circular dependence to work correctly in all situations we'll need to be
- // sure to correctly apply the `--start-group` and `--end-group` options to
- // GNU linkers, otherwise if we don't use any other symbol from the standard
- // library it'll get discarded and the whole application won't link.
- //
- // In this loop we're calculating the `group_end`, after which crate to
- // pass `--end-group` and `group_start`, before which crate to pass
- // `--start-group`. We currently do this by passing `--end-group` after
- // the first crate (when iterating backwards) that requires a lang item
- // defined somewhere else. Once that's set then when we've defined all the
- // necessary lang items we'll pass `--start-group`.
- //
- // Note that this isn't amazing logic for now but it should do the trick
- // for the current implementation of the standard library.
- let mut group_end = None;
- let mut group_start = None;
- // Crates available for linking thus far.
- let mut available = FxHashSet::default();
- // Crates required to satisfy dependencies discovered so far.
- let mut required = FxHashSet::default();
-
- let info = &codegen_results.crate_info;
- for &cnum in deps.iter().rev() {
- if let Some(missing) = info.missing_lang_items.get(&cnum) {
- let missing_crates = missing.iter().map(|i| info.lang_item_to_crate.get(i).copied());
- required.extend(missing_crates);
- }
-
- required.insert(Some(cnum));
- available.insert(Some(cnum));
-
- if required.len() > available.len() && group_end.is_none() {
- group_end = Some(cnum);
- }
- if required.len() == available.len() && group_end.is_some() {
- group_start = Some(cnum);
- break;
- }
- }
-
- // If we didn't end up filling in all lang items from upstream crates then
- // we'll be filling it in with our crate. This probably means we're the
- // standard library itself, so skip this for now.
- if group_end.is_some() && group_start.is_none() {
- group_end = None;
- }
-
let mut compiler_builtins = None;
let search_path = OnceCell::new();
for &cnum in deps.iter() {
- if group_start == Some(cnum) {
- cmd.group_start();
- }
-
// We may not pass all crates through to the linker. Some crates may
// appear statically in an existing dylib, meaning we'll pick up all the
// symbols from the dylib.
bundle: Some(false),
whole_archive: Some(false) | None,
} => {
+ // HACK/FIXME: Fixup a circular dependency between libgcc and libc
+ // with glibc. This logic should be moved to the libc crate.
+ if sess.target.os == "linux"
+ && sess.target.env == "gnu"
+ && name == "c"
+ {
+ cmd.link_staticlib("gcc", false);
+ }
cmd.link_staticlib(name, lib.verbatim.unwrap_or(false));
}
NativeLibKind::LinkArg => {
}
Linkage::Dynamic => add_dynamic_crate(cmd, sess, &src.dylib.as_ref().unwrap().0),
}
-
- if group_end == Some(cnum) {
- cmd.group_end();
- }
}
// compiler-builtins are always placed last to ensure that they're
fn no_default_libraries(&mut self);
fn export_symbols(&mut self, tmpdir: &Path, crate_type: CrateType, symbols: &[String]);
fn subsystem(&mut self, subsystem: &str);
- fn group_start(&mut self);
- fn group_end(&mut self);
fn linker_plugin_lto(&mut self);
fn add_eh_frame_header(&mut self) {}
fn add_no_exec(&mut self) {}
self.hint_dynamic(); // Reset to default before returning the composed command line.
}
- fn group_start(&mut self) {
- if self.takes_hints() {
- self.linker_arg("--start-group");
- }
- }
-
- fn group_end(&mut self) {
- if self.takes_hints() {
- self.linker_arg("--end-group");
- }
- }
-
fn linker_plugin_lto(&mut self) {
match self.sess.opts.cg.linker_plugin_lto {
LinkerPluginLto::Disabled => {
}
}
- // MSVC doesn't need group indicators
- fn group_start(&mut self) {}
- fn group_end(&mut self) {}
-
fn linker_plugin_lto(&mut self) {
// Do nothing
}
// noop
}
- // Appears not necessary on Emscripten
- fn group_start(&mut self) {}
- fn group_end(&mut self) {}
-
fn linker_plugin_lto(&mut self) {
// Do nothing
}
fn subsystem(&mut self, _subsystem: &str) {}
- // Not needed for now with LLD
- fn group_start(&mut self) {}
- fn group_end(&mut self) {}
-
fn linker_plugin_lto(&mut self) {
// Do nothing for now
}
self.hint_static(); // Reset to default before returning the composed command line.
}
- fn group_start(&mut self) {
- self.cmd.arg("--start-group");
- }
-
- fn group_end(&mut self) {
- self.cmd.arg("--end-group");
- }
-
fn linker_plugin_lto(&mut self) {}
fn control_flow_guard(&mut self) {}
fn subsystem(&mut self, _subsystem: &str) {}
- fn group_start(&mut self) {}
-
- fn group_end(&mut self) {}
-
fn linker_plugin_lto(&mut self) {}
}
fn subsystem(&mut self, _subsystem: &str) {}
- fn group_start(&mut self) {}
-
- fn group_end(&mut self) {}
-
fn linker_plugin_lto(&mut self) {}
}
use crate::{CachedModuleCodegen, CompiledModule, CrateInfo, MemFlags, ModuleCodegen, ModuleKind};
use rustc_attr as attr;
-use rustc_data_structures::fx::FxHashMap;
+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_iter;
use rustc_hir as hir;
use rustc_hir::def_id::{DefId, LOCAL_CRATE};
use rustc_hir::lang_items::LangItem;
+use rustc_hir::weak_lang_items::WEAK_ITEMS_SYMBOLS;
use rustc_index::vec::Idx;
use rustc_metadata::EncodedMetadata;
use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
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::ty::layout::{HasTyCtxt, LayoutOf, TyAndLayout};
use rustc_session::config::{self, CrateType, EntryFnType, OutputType};
use rustc_session::Session;
use rustc_span::symbol::sym;
+use rustc_span::Symbol;
use rustc_span::{DebuggerVisualizerFile, DebuggerVisualizerType};
use rustc_target::abi::{Align, VariantIdx};
crate_name: Default::default(),
used_crates,
used_crate_source: Default::default(),
- lang_item_to_crate: Default::default(),
- missing_lang_items: Default::default(),
dependency_formats: tcx.dependency_formats(()).clone(),
windows_subsystem,
natvis_debugger_visualizers: Default::default(),
};
- let lang_items = tcx.lang_items();
-
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);
- info.missing_lang_items.reserve(n_crates);
for &cnum in crates.iter() {
info.native_libraries
if tcx.is_no_builtins(cnum) {
info.is_no_builtins.insert(cnum);
}
- let missing = tcx.missing_lang_items(cnum);
- for &item in missing.iter() {
- if let Ok(id) = lang_items.require(item) {
- info.lang_item_to_crate.insert(item, id.krate);
- }
- }
+ }
- // No need to look for lang items that don't actually need to exist.
- let missing =
- missing.iter().cloned().filter(|&l| lang_items::required(tcx, l)).collect();
- info.missing_lang_items.insert(cnum, missing);
+ // Handle circular dependencies in the standard library.
+ // See comment before `add_linked_symbol_object` function for the details.
+ // With msvc-like linkers it's both unnecessary (they support circular dependencies),
+ // and causes linking issues (when weak lang item symbols are "privatized" by LTO).
+ let target = &tcx.sess.target;
+ if !target.is_like_msvc {
+ let missing_weak_lang_items: FxHashSet<&Symbol> = info
+ .used_crates
+ .iter()
+ .flat_map(|cnum| {
+ tcx.missing_lang_items(*cnum)
+ .iter()
+ .filter(|l| lang_items::required(tcx, **l))
+ .filter_map(|item| WEAK_ITEMS_SYMBOLS.get(item))
+ })
+ .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)),
+ )
+ });
}
let embed_visualizers = tcx.sess.crate_types().iter().any(|&crate_type| match crate_type {
}
});
- if tcx.sess.target.is_like_msvc && embed_visualizers {
+ if target.is_like_msvc && embed_visualizers {
info.natvis_debugger_visualizers =
collect_debugger_visualizers_transitive(tcx, DebuggerVisualizerType::Natvis);
}
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::sync::Lrc;
use rustc_hir::def_id::CrateNum;
-use rustc_hir::LangItem;
use rustc_middle::dep_graph::WorkProduct;
use rustc_middle::middle::dependency_format::Dependencies;
use rustc_middle::middle::exported_symbols::SymbolExportKind;
pub used_libraries: Vec<NativeLib>,
pub used_crate_source: FxHashMap<CrateNum, Lrc<CrateSource>>,
pub used_crates: Vec<CrateNum>,
- pub lang_item_to_crate: FxHashMap<LangItem, CrateNum>,
- pub missing_lang_items: FxHashMap<CrateNum, Vec<LangItem>>,
pub dependency_formats: Lrc<Dependencies>,
pub windows_subsystem: Option<String>,
pub natvis_debugger_visualizers: BTreeSet<DebuggerVisualizerFile>,
map
});
+pub static WEAK_ITEMS_SYMBOLS: LazyLock<FxIndexMap<LangItem, Symbol>> = LazyLock::new(|| {
+ let mut map = FxIndexMap::default();
+ $(map.insert(LangItem::$item, sym::$sym);)*
+ map
+});
+
pub fn link_name(attrs: &[ast::Attribute]) -> Option<Symbol>
{
lang_items::extract(attrs).and_then(|(name, _)| {
projects / rust.git / commitdiff