diff options
| -rw-r--r-- | compiler/rustc_codegen_ssa/src/back/link.rs | 71 | ||||
| -rw-r--r-- | compiler/rustc_session/src/config.rs | 44 | ||||
| -rw-r--r-- | compiler/rustc_session/src/options.rs | 20 | ||||
| -rw-r--r-- | compiler/rustc_target/src/spec/mod.rs | 74 | ||||
| -rw-r--r-- | src/doc/unstable-book/src/compiler-flags/linker-features.md | 35 | ||||
| -rw-r--r-- | tests/run-make/rust-lld/Makefile | 6 |
6 files changed, 223 insertions, 27 deletions
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs index 813d4014f88..10e0f6680ed 100644 --- a/compiler/rustc_codegen_ssa/src/back/link.rs +++ b/compiler/rustc_codegen_ssa/src/back/link.rs @@ -11,6 +11,7 @@ use rustc_metadata::fs::{copy_to_stdout, emit_wrapper_file, METADATA_FILENAME}; use rustc_middle::middle::debugger_visualizer::DebuggerVisualizerFile; use rustc_middle::middle::dependency_format::Linkage; use rustc_middle::middle::exported_symbols::SymbolExportKind; +use rustc_session::config::LinkerFeaturesCli; use rustc_session::config::{self, CFGuard, CrateType, DebugInfo, OutFileName, Strip}; use rustc_session::config::{OutputFilenames, OutputType, PrintKind, SplitDwarfKind}; use rustc_session::cstore::DllImport; @@ -22,10 +23,10 @@ use rustc_session::utils::NativeLibKind; use rustc_session::{filesearch, Session}; use rustc_span::symbol::Symbol; use rustc_target::spec::crt_objects::CrtObjects; -use rustc_target::spec::LinkSelfContainedComponents; use rustc_target::spec::LinkSelfContainedDefault; use rustc_target::spec::LinkerFlavorCli; use rustc_target::spec::{Cc, LinkOutputKind, LinkerFlavor, Lld, PanicStrategy}; +use rustc_target::spec::{LinkSelfContainedComponents, LinkerFeatures}; use rustc_target::spec::{RelocModel, RelroLevel, SanitizerSet, SplitDebuginfo}; use super::archive::{ArchiveBuilder, ArchiveBuilderBuilder}; @@ -76,8 +77,8 @@ pub fn ensure_removed(dcx: &DiagCtxt, path: &Path) { /// Performs the linkage portion of the compilation phase. This will generate all /// of the requested outputs for this compilation session. -pub fn link_binary<'a>( - sess: &'a Session, +pub fn link_binary( + sess: &Session, archive_builder_builder: &dyn ArchiveBuilderBuilder, codegen_results: &CodegenResults, outputs: &OutputFilenames, @@ -465,9 +466,9 @@ fn link_rlib<'a>( /// then the CodegenResults value contains one NativeLib instance for each block. However, the /// linker appears to expect only a single import library for each library used, so we need to /// collate the symbols together by library name before generating the import libraries. -fn collate_raw_dylibs<'a, 'b>( - sess: &'a Session, - used_libraries: impl IntoIterator<Item = &'b NativeLib>, +fn collate_raw_dylibs<'a>( + sess: &Session, + used_libraries: impl IntoIterator<Item = &'a NativeLib>, ) -> Result<Vec<(String, Vec<DllImport>)>, ErrorGuaranteed> { // Use index maps to preserve original order of imports and libraries. let mut dylib_table = FxIndexMap::<String, FxIndexMap<Symbol, &DllImport>>::default(); @@ -514,8 +515,8 @@ fn collate_raw_dylibs<'a, 'b>( /// /// There's no need to include metadata in a static archive, so ensure to not link in the metadata /// object file (and also don't prepare the archive with a metadata file). -fn link_staticlib<'a>( - sess: &'a Session, +fn link_staticlib( + sess: &Session, archive_builder_builder: &dyn ArchiveBuilderBuilder, codegen_results: &CodegenResults, out_filename: &Path, @@ -627,11 +628,7 @@ fn link_staticlib<'a>( /// Use `thorin` (rust implementation of a dwarf packaging utility) to link DWARF objects into a /// DWARF package. -fn link_dwarf_object<'a>( - sess: &'a Session, - cg_results: &CodegenResults, - executable_out_filename: &Path, -) { +fn link_dwarf_object(sess: &Session, cg_results: &CodegenResults, executable_out_filename: &Path) { let mut dwp_out_filename = executable_out_filename.to_path_buf().into_os_string(); dwp_out_filename.push(".dwp"); debug!(?dwp_out_filename, ?executable_out_filename); @@ -735,8 +732,8 @@ fn link_dwarf_object<'a>( /// /// This will invoke the system linker/cc to create the resulting file. This links to all upstream /// files as well. -fn link_natively<'a>( - sess: &'a Session, +fn link_natively( + sess: &Session, archive_builder_builder: &dyn ArchiveBuilderBuilder, crate_type: CrateType, out_filename: &Path, @@ -1100,8 +1097,8 @@ fn link_natively<'a>( Ok(()) } -fn strip_symbols_with_external_utility<'a>( - sess: &'a Session, +fn strip_symbols_with_external_utility( + sess: &Session, util: &str, out_filename: &Path, option: Option<&str>, @@ -1338,7 +1335,9 @@ pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) { sess: &Session, linker: Option<PathBuf>, flavor: Option<LinkerFlavor>, + features: LinkerFeaturesCli, ) -> Option<(PathBuf, LinkerFlavor)> { + let flavor = flavor.map(|flavor| adjust_flavor_to_features(flavor, features)); match (linker, flavor) { (Some(linker), Some(flavor)) => Some((linker, flavor)), // only the linker flavor is known; use the default linker for the selected flavor @@ -1386,12 +1385,33 @@ pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) { sess.dcx().emit_fatal(errors::LinkerFileStem); }); let flavor = sess.target.linker_flavor.with_linker_hints(stem); + let flavor = adjust_flavor_to_features(flavor, features); Some((linker, flavor)) } (None, None) => None, } } + // While linker flavors and linker features are isomorphic (and thus targets don't need to + // define features separately), we use the flavor as the root piece of data and have the + // linker-features CLI flag influence *that*, so that downstream code does not have to check for + // both yet. + fn adjust_flavor_to_features( + flavor: LinkerFlavor, + features: LinkerFeaturesCli, + ) -> LinkerFlavor { + // Note: a linker feature cannot be both enabled and disabled on the CLI. + if features.enabled.contains(LinkerFeatures::LLD) { + flavor.with_lld_enabled() + } else if features.disabled.contains(LinkerFeatures::LLD) { + flavor.with_lld_disabled() + } else { + flavor + } + } + + let features = sess.opts.unstable_opts.linker_features; + // linker and linker flavor specified via command line have precedence over what the target // specification specifies let linker_flavor = match sess.opts.cg.linker_flavor { @@ -1405,7 +1425,7 @@ pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) { .linker_flavor .map(|flavor| sess.target.linker_flavor.with_cli_hints(flavor)), }; - if let Some(ret) = infer_from(sess, sess.opts.cg.linker.clone(), linker_flavor) { + if let Some(ret) = infer_from(sess, sess.opts.cg.linker.clone(), linker_flavor, features) { return ret; } @@ -1413,6 +1433,7 @@ pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) { sess, sess.target.linker.as_deref().map(PathBuf::from), Some(sess.target.linker_flavor), + features, ) { return ret; } @@ -2105,10 +2126,10 @@ fn add_rpath_args( /// to the linking process as a whole. /// Order-independent options may still override each other in order-dependent fashion, /// e.g `--foo=yes --foo=no` may be equivalent to `--foo=no`. -fn linker_with_args<'a>( +fn linker_with_args( path: &Path, flavor: LinkerFlavor, - sess: &'a Session, + sess: &Session, archive_builder_builder: &dyn ArchiveBuilderBuilder, crate_type: CrateType, tmpdir: &Path, @@ -2640,9 +2661,9 @@ fn add_local_native_libraries( ); } -fn add_upstream_rust_crates<'a>( +fn add_upstream_rust_crates( cmd: &mut dyn Linker, - sess: &'a Session, + sess: &Session, archive_builder_builder: &dyn ArchiveBuilderBuilder, codegen_results: &CodegenResults, crate_type: CrateType, @@ -2779,7 +2800,7 @@ fn add_upstream_native_libraries( // file generated by the MSVC linker. See https://github.com/rust-lang/rust/issues/112586. // // The returned path will always have `fix_windows_verbatim_for_gcc()` applied to it. -fn rehome_sysroot_lib_dir<'a>(sess: &'a Session, lib_dir: &Path) -> PathBuf { +fn rehome_sysroot_lib_dir(sess: &Session, lib_dir: &Path) -> PathBuf { let sysroot_lib_path = sess.target_filesearch(PathKind::All).get_lib_path(); let canonical_sysroot_lib_path = { try_canonicalize(&sysroot_lib_path).unwrap_or_else(|_| sysroot_lib_path.clone()) }; @@ -2812,9 +2833,9 @@ fn rehome_sysroot_lib_dir<'a>(sess: &'a Session, lib_dir: &Path) -> PathBuf { // Note, however, that if we're not doing LTO we can just pass the rlib // blindly to the linker (fast) because it's fine if it's not actually // included as we're at the end of the dependency chain. -fn add_static_crate<'a>( +fn add_static_crate( cmd: &mut dyn Linker, - sess: &'a Session, + sess: &Session, archive_builder_builder: &dyn ArchiveBuilderBuilder, codegen_results: &CodegenResults, tmpdir: &Path, diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs index a4919b25fe3..34acb4ea10f 100644 --- a/compiler/rustc_session/src/config.rs +++ b/compiler/rustc_session/src/config.rs @@ -18,7 +18,7 @@ use rustc_feature::UnstableFeatures; use rustc_span::edition::{Edition, DEFAULT_EDITION, EDITION_NAME_LIST, LATEST_STABLE_EDITION}; use rustc_span::source_map::FilePathMapping; use rustc_span::{FileName, FileNameDisplayPreference, RealFileName, SourceFileHashAlgorithm}; -use rustc_target::spec::LinkSelfContainedComponents; +use rustc_target::spec::{LinkSelfContainedComponents, LinkerFeatures}; use rustc_target::spec::{SplitDebuginfo, Target, TargetTriple}; use std::collections::btree_map::{ Iter as BTreeMapIter, Keys as BTreeMapKeysIter, Values as BTreeMapValuesIter, @@ -292,6 +292,48 @@ impl LinkSelfContained { } } +/// The different values that `-Z linker-features` can take on the CLI: a list of individually +/// enabled or disabled features used during linking. +/// +/// There is no need to enable or disable them in bulk. Each feature is fine-grained, and can be +/// used to turn `LinkerFeatures` on or off, without needing to change the linker flavor: +/// - using the system lld, or the self-contained `rust-lld` linker +/// - using a C/C++ compiler to drive the linker (not yet exposed on the CLI) +/// - etc. +#[derive(Default, Copy, Clone, PartialEq, Debug)] +pub struct LinkerFeaturesCli { + /// The linker features that are enabled on the CLI, using the `+feature` syntax. + pub enabled: LinkerFeatures, + + /// The linker features that are disabled on the CLI, using the `-feature` syntax. + pub disabled: LinkerFeatures, +} + +impl LinkerFeaturesCli { + /// Accumulates an enabled or disabled feature as specified on the CLI, if possible. + /// For example: `+lld`, and `-lld`. + pub(crate) fn handle_cli_feature(&mut self, feature: &str) -> Option<()> { + // Duplicate flags are reduced as we go, the last occurrence wins: + // `+feature,-feature,+feature` only enables the feature, and does not record it as both + // enabled and disabled on the CLI. + // We also only expose `+/-lld` at the moment, as it's currenty the only implemented linker + // feature and toggling `LinkerFeatures::CC` would be a noop. + match feature { + "+lld" => { + self.enabled.insert(LinkerFeatures::LLD); + self.disabled.remove(LinkerFeatures::LLD); + Some(()) + } + "-lld" => { + self.disabled.insert(LinkerFeatures::LLD); + self.enabled.remove(LinkerFeatures::LLD); + Some(()) + } + _ => None, + } + } +} + /// Used with `-Z assert-incr-state`. #[derive(Clone, Copy, PartialEq, Hash, Debug)] pub enum IncrementalStateAssertion { diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs index 5e7c2465097..963c9558c17 100644 --- a/compiler/rustc_session/src/options.rs +++ b/compiler/rustc_session/src/options.rs @@ -426,6 +426,8 @@ mod desc { "one of supported split dwarf modes (`split` or `single`)"; pub const parse_link_self_contained: &str = "one of: `y`, `yes`, `on`, `n`, `no`, `off`, or a list of enabled (`+` prefix) and disabled (`-` prefix) \ components: `crto`, `libc`, `unwind`, `linker`, `sanitizers`, `mingw`"; + pub const parse_linker_features: &str = + "a list of enabled (`+` prefix) and disabled (`-` prefix) features: `lld`"; pub const parse_polonius: &str = "either no value or `legacy` (the default), or `next`"; pub const parse_stack_protector: &str = "one of (`none` (default), `basic`, `strong`, or `all`)"; @@ -1269,6 +1271,22 @@ mod parse { true } + /// Parse a comma-separated list of enabled and disabled linker features. + pub(crate) fn parse_linker_features(slot: &mut LinkerFeaturesCli, v: Option<&str>) -> bool { + match v { + Some(s) => { + for feature in s.split(',') { + if slot.handle_cli_feature(feature).is_none() { + return false; + } + } + + true + } + None => false, + } + } + pub(crate) fn parse_wasi_exec_model(slot: &mut Option<WasiExecModel>, v: Option<&str>) -> bool { match v { Some("command") => *slot = Some(WasiExecModel::Command), @@ -1721,6 +1739,8 @@ options! { "link native libraries in the linker invocation (default: yes)"), link_only: bool = (false, parse_bool, [TRACKED], "link the `.rlink` file generated by `-Z no-link` (default: no)"), + linker_features: LinkerFeaturesCli = (LinkerFeaturesCli::default(), parse_linker_features, [UNTRACKED], + "a comma-separated list of linker features to enable (+) or disable (-): `lld`"), lint_mir: bool = (false, parse_bool, [UNTRACKED], "lint MIR before and after each transformation"), llvm_module_flag: Vec<(String, u32, String)> = (Vec::new(), parse_llvm_module_flag, [TRACKED], diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs index e94c7f3cc58..3a69b19ee60 100644 --- a/compiler/rustc_target/src/spec/mod.rs +++ b/compiler/rustc_target/src/spec/mod.rs @@ -448,6 +448,28 @@ impl LinkerFlavor { | LinkerFlavor::Ptx => false, } } + + /// For flavors with an `Lld` component, ensure it's enabled. Otherwise, returns the given + /// flavor unmodified. + pub fn with_lld_enabled(self) -> LinkerFlavor { + match self { + LinkerFlavor::Gnu(cc, Lld::No) => LinkerFlavor::Gnu(cc, Lld::Yes), + LinkerFlavor::Darwin(cc, Lld::No) => LinkerFlavor::Darwin(cc, Lld::Yes), + LinkerFlavor::Msvc(Lld::No) => LinkerFlavor::Msvc(Lld::Yes), + _ => self, + } + } + + /// For flavors with an `Lld` component, ensure it's disabled. Otherwise, returns the given + /// flavor unmodified. + pub fn with_lld_disabled(self) -> LinkerFlavor { + match self { + LinkerFlavor::Gnu(cc, Lld::Yes) => LinkerFlavor::Gnu(cc, Lld::No), + LinkerFlavor::Darwin(cc, Lld::Yes) => LinkerFlavor::Darwin(cc, Lld::No), + LinkerFlavor::Msvc(Lld::Yes) => LinkerFlavor::Msvc(Lld::No), + _ => self, + } + } } macro_rules! linker_flavor_cli_impls { @@ -698,6 +720,58 @@ impl ToJson for LinkSelfContainedComponents { } } +bitflags::bitflags! { + /// The `-Z linker-features` components that can individually be enabled or disabled. + /// + /// They are feature flags intended to be a more flexible mechanism than linker flavors, and + /// also to prevent a combinatorial explosion of flavors whenever a new linker feature is + /// required. These flags are "generic", in the sense that they can work on multiple targets on + /// the CLI. Otherwise, one would have to select different linkers flavors for each target. + /// + /// Here are some examples of the advantages they offer: + /// - default feature sets for principal flavors, or for specific targets. + /// - flavor-specific features: for example, clang offers automatic cross-linking with + /// `--target`, which gcc-style compilers don't support. The *flavor* is still a C/C++ + /// compiler, and we don't need to multiply the number of flavors for this use-case. Instead, + /// we can have a single `+target` feature. + /// - umbrella features: for example if clang accumulates more features in the future than just + /// the `+target` above. That could be modeled as `+clang`. + /// - niche features for resolving specific issues: for example, on Apple targets the linker + /// flag implementing the `as-needed` native link modifier (#99424) is only possible on + /// sufficiently recent linker versions. + /// - still allows for discovery and automation, for example via feature detection. This can be + /// useful in exotic environments/build systems. + #[derive(Clone, Copy, PartialEq, Eq, Default)] + pub struct LinkerFeatures: u8 { + /// Invoke the linker via a C/C++ compiler (e.g. on most unix targets). + const CC = 1 << 0; + /// Use the lld linker, either the system lld or the self-contained linker `rust-lld`. + const LLD = 1 << 1; + } +} +rustc_data_structures::external_bitflags_debug! { LinkerFeatures } + +impl LinkerFeatures { + /// Parses a single `-Z linker-features` well-known feature, not a set of flags. + pub fn from_str(s: &str) -> Option<LinkerFeatures> { + Some(match s { + "cc" => LinkerFeatures::CC, + "lld" => LinkerFeatures::LLD, + _ => return None, + }) + } + + /// Returns whether the `lld` linker feature is enabled. + pub fn is_lld_enabled(self) -> bool { + self.contains(LinkerFeatures::LLD) + } + + /// Returns whether the `cc` linker feature is enabled. + pub fn is_cc_enabled(self) -> bool { + self.contains(LinkerFeatures::CC) + } +} + #[derive(Clone, Copy, Debug, PartialEq, Hash, Encodable, Decodable, HashStable_Generic)] pub enum PanicStrategy { Unwind, diff --git a/src/doc/unstable-book/src/compiler-flags/linker-features.md b/src/doc/unstable-book/src/compiler-flags/linker-features.md new file mode 100644 index 00000000000..643fcf7c6d7 --- /dev/null +++ b/src/doc/unstable-book/src/compiler-flags/linker-features.md @@ -0,0 +1,35 @@ +# `linker-features` + +-------------------- + +The `-Zlinker-features` compiler flag allows enabling or disabling specific features used during +linking, and is intended to be stabilized under the codegen options as `-Clinker-features`. + +These feature flags are a flexible extension mechanism that is complementary to linker flavors, +designed to avoid the combinatorial explosion of having to create a new set of flavors for each +linker feature we'd want to use. + +For example, this design allows: +- default feature sets for principal flavors, or for specific targets. +- flavor-specific features: for example, clang offers automatic cross-linking with `--target`, which + gcc-style compilers don't support. The *flavor* is still a C/C++ compiler, and we don't want to + multiply the number of flavors for this use-case. Instead, we can have a single `+target` feature. +- umbrella features: for example, if clang accumulates more features in the future than just the + `+target` above. That could be modeled as `+clang`. +- niche features for resolving specific issues: for example, on Apple targets the linker flag + implementing the `as-needed` native link modifier (#99424) is only possible on sufficiently recent + linker versions. +- still allows for discovery and automation, for example via feature detection. This can be useful + in exotic environments/build systems. + +The flag accepts a comma-separated list of features, individually enabled (`+features`) or disabled +(`-features`), though currently only one is exposed on the CLI: +- `lld`: to toggle using the lld linker, either the system-installed binary, or the self-contained + `rust-lld` linker. + +As described above, this list is intended to grow in the future. + +One of the most common uses of this flag will be to toggle self-contained linking with `rust-lld` on +and off: `-Clinker-features=+lld -Clink-self-contained=+linker` will use the toolchain's `rust-lld` +as the linker. Inversely, `-Clinker-features=-lld` would opt out of that, if the current target had +self-contained linking enabled by default. diff --git a/tests/run-make/rust-lld/Makefile b/tests/run-make/rust-lld/Makefile index f8526530d4d..1ecac479f41 100644 --- a/tests/run-make/rust-lld/Makefile +++ b/tests/run-make/rust-lld/Makefile @@ -4,5 +4,9 @@ include ../tools.mk # needs-rust-lld # ignore-s390x lld does not yet support s390x as target all: - RUSTC_LOG=rustc_codegen_ssa::back::link=info $(RUSTC) -Clink-self-contained=+linker -Clinker-flavor=gnu-lld-cc -Zunstable-options -Clink-args=-Wl,-v main.rs 2> $(TMPDIR)/output.txt + RUSTC_LOG=rustc_codegen_ssa::back::link=info $(RUSTC) -Clink-self-contained=+linker -Zlinker-features=+lld -Zunstable-options -Clink-args=-Wl,-v main.rs 2> $(TMPDIR)/output.txt + $(CGREP) -e "^LLD [0-9]+\.[0-9]+\.[0-9]+" < $(TMPDIR)/output.txt + + # while we're here, also check that the last linker feature flag "wins" + RUSTC_LOG=rustc_codegen_ssa::back::link=info $(RUSTC) -Clink-self-contained=+linker -Zlinker-features=-lld -Zlinker-features=+lld -Zunstable-options -Clink-args=-Wl,-v main.rs 2> $(TMPDIR)/output.txt $(CGREP) -e "^LLD [0-9]+\.[0-9]+\.[0-9]+" < $(TMPDIR)/output.txt |