diff options
Diffstat (limited to 'compiler/rustc_codegen_ssa/src/back/link.rs')
| -rw-r--r-- | compiler/rustc_codegen_ssa/src/back/link.rs | 98 |
1 files changed, 76 insertions, 22 deletions
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs index 105a4cb81f0..b090730ac6b 100644 --- a/compiler/rustc_codegen_ssa/src/back/link.rs +++ b/compiler/rustc_codegen_ssa/src/back/link.rs @@ -244,22 +244,17 @@ pub fn each_linked_rlib( fmts } else { - for combination in info.dependency_formats.iter().combinations(2) { - let (ty1, list1) = &combination[0]; - let (ty2, list2) = &combination[1]; - if list1 != list2 { - return Err(errors::LinkRlibError::IncompatibleDependencyFormats { - ty1: format!("{ty1:?}"), - ty2: format!("{ty2:?}"), - list1: format!("{list1:?}"), - list2: format!("{list2:?}"), - }); - } - } - if info.dependency_formats.is_empty() { - return Err(errors::LinkRlibError::MissingFormat); + let mut dep_formats = info.dependency_formats.iter(); + let (ty1, list1) = dep_formats.next().ok_or(errors::LinkRlibError::MissingFormat)?; + if let Some((ty2, list2)) = dep_formats.find(|(_, list2)| list1 != *list2) { + return Err(errors::LinkRlibError::IncompatibleDependencyFormats { + ty1: format!("{ty1:?}"), + ty2: format!("{ty2:?}"), + list1: format!("{list1:?}"), + list2: format!("{list2:?}"), + }); } - info.dependency_formats.first().unwrap().1 + list1 }; let used_dep_crates = info.used_crates.iter(); @@ -626,10 +621,9 @@ fn link_staticlib( let mut all_rust_dylibs = vec![]; for &cnum in crates { - match fmts.get(cnum) { - Some(&Linkage::Dynamic) => {} - _ => continue, - } + let Some(Linkage::Dynamic) = fmts.get(cnum) else { + continue; + }; let crate_name = codegen_results.crate_info.crate_name[&cnum]; let used_crate_source = &codegen_results.crate_info.used_crate_source[&cnum]; if let Some((path, _)) = &used_crate_source.dylib { @@ -1990,6 +1984,7 @@ fn add_pre_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) if let Some(args) = sess.target.pre_link_args.get(&flavor) { cmd.verbatim_args(args.iter().map(Deref::deref)); } + cmd.verbatim_args(&sess.opts.unstable_opts.pre_link_args); } @@ -2063,8 +2058,8 @@ fn add_post_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor /// linker, and since they never participate in the linking, using `KEEP` in the linker scripts /// can't keep them either. This causes #47384. /// -/// To keep them around, we could use `--whole-archive` and equivalents to force rlib to -/// participate in linking like object files, but this proves to be expensive (#93791). Therefore +/// To keep them around, we could use `--whole-archive`, `-force_load` and equivalents to force rlib +/// to participate in linking like object files, but this proves to be expensive (#93791). Therefore /// we instead just introduce an undefined reference to them. This could be done by `-u` command /// line option to the linker or `EXTERN(...)` in linker scripts, however they does not only /// introduce an undefined reference, but also make them the GC roots, preventing `--gc-sections` @@ -2106,8 +2101,20 @@ fn add_linked_symbol_object( file.set_mangling(object::write::Mangling::None); } + // ld64 requires a relocation to load undefined symbols, see below. + // Not strictly needed if linking with lld, but might as well do it there too. + let ld64_section_helper = if file.format() == object::BinaryFormat::MachO { + Some(file.add_section( + file.segment_name(object::write::StandardSegment::Data).to_vec(), + "__data".into(), + object::SectionKind::Data, + )) + } else { + None + }; + for (sym, kind) in symbols.iter() { - file.add_symbol(object::write::Symbol { + let symbol = file.add_symbol(object::write::Symbol { name: sym.clone().into(), value: 0, size: 0, @@ -2121,6 +2128,47 @@ fn add_linked_symbol_object( section: object::write::SymbolSection::Undefined, flags: object::SymbolFlags::None, }); + + // The linker shipped with Apple's Xcode, ld64, works a bit differently from other linkers. + // + // Code-wise, the relevant parts of ld64 are roughly: + // 1. Find the `ArchiveLoadMode` based on commandline options, default to `parseObjects`. + // https://github.com/apple-oss-distributions/ld64/blob/ld64-954.16/src/ld/Options.cpp#L924-L932 + // https://github.com/apple-oss-distributions/ld64/blob/ld64-954.16/src/ld/Options.h#L55 + // + // 2. Read the archive table of contents (__.SYMDEF file). + // https://github.com/apple-oss-distributions/ld64/blob/ld64-954.16/src/ld/parsers/archive_file.cpp#L294-L325 + // + // 3. Begin linking by loading "atoms" from input files. + // https://github.com/apple-oss-distributions/ld64/blob/ld64-954.16/doc/design/linker.html + // https://github.com/apple-oss-distributions/ld64/blob/ld64-954.16/src/ld/InputFiles.cpp#L1349 + // + // a. Directly specified object files (`.o`) are parsed immediately. + // https://github.com/apple-oss-distributions/ld64/blob/ld64-954.16/src/ld/parsers/macho_relocatable_file.cpp#L4611-L4627 + // + // - Undefined symbols are not atoms (`n_value > 0` denotes a common symbol). + // https://github.com/apple-oss-distributions/ld64/blob/ld64-954.16/src/ld/parsers/macho_relocatable_file.cpp#L2455-L2468 + // https://maskray.me/blog/2022-02-06-all-about-common-symbols + // + // - Relocations/fixups are atoms. + // https://github.com/apple-oss-distributions/ld64/blob/ce6341ae966b3451aa54eeb049f2be865afbd578/src/ld/parsers/macho_relocatable_file.cpp#L2088-L2114 + // + // b. Archives are not parsed yet. + // https://github.com/apple-oss-distributions/ld64/blob/ld64-954.16/src/ld/parsers/archive_file.cpp#L467-L577 + // + // 4. When a symbol is needed by an atom, parse the object file that contains the symbol. + // https://github.com/apple-oss-distributions/ld64/blob/ld64-954.16/src/ld/InputFiles.cpp#L1417-L1491 + // https://github.com/apple-oss-distributions/ld64/blob/ld64-954.16/src/ld/parsers/archive_file.cpp#L579-L597 + // + // All of the steps above are fairly similar to other linkers, except that **it completely + // ignores undefined symbols**. + // + // So to make this trick work on ld64, we need to do something else to load the relevant + // object files. We do this by inserting a relocation (fixup) for each symbol. + if let Some(section) = ld64_section_helper { + apple::add_data_and_relocation(&mut file, section, symbol, &sess.target, *kind) + .expect("failed adding relocation"); + } } let path = tmpdir.join("symbols.o"); @@ -2518,6 +2566,12 @@ fn add_order_independent_options( "--target-cpu", &codegen_results.crate_info.target_cpu, ]); + if codegen_results.crate_info.target_features.len() > 0 { + cmd.link_arg(&format!( + "--target-feature={}", + &codegen_results.crate_info.target_features.join(",") + )); + } } else if flavor == LinkerFlavor::Ptx { cmd.link_args(&["--fallback-arch", &codegen_results.crate_info.target_cpu]); } else if flavor == LinkerFlavor::Bpf { |