From 49cc6d1f843749dab51aa71925f4afd4fad9c419 Mon Sep 17 00:00:00 2001 From: Gary Guo Date: Sat, 2 Apr 2022 22:27:33 +0100 Subject: Add `SymbolExportInfo` This is currently a wrapper to `SymbolExportLevel` but it allows later addition of extra information. --- compiler/rustc_codegen_ssa/src/back/linker.rs | 8 +-- .../rustc_codegen_ssa/src/back/symbol_export.rs | 60 ++++++++++++++++------ compiler/rustc_codegen_ssa/src/back/write.rs | 4 +- 3 files changed, 51 insertions(+), 21 deletions(-) (limited to 'compiler/rustc_codegen_ssa/src') diff --git a/compiler/rustc_codegen_ssa/src/back/linker.rs b/compiler/rustc_codegen_ssa/src/back/linker.rs index 3a66bfafaf3..a90b8a62c62 100644 --- a/compiler/rustc_codegen_ssa/src/back/linker.rs +++ b/compiler/rustc_codegen_ssa/src/back/linker.rs @@ -1526,8 +1526,8 @@ pub(crate) fn exported_symbols(tcx: TyCtxt<'_>, crate_type: CrateType) -> Vec, crate_type: CrateType) -> Vec SymbolExportLevel { } } -fn reachable_non_generics_provider(tcx: TyCtxt<'_>, cnum: CrateNum) -> DefIdMap { +fn reachable_non_generics_provider(tcx: TyCtxt<'_>, cnum: CrateNum) -> DefIdMap { assert_eq!(cnum, LOCAL_CRATE); if !tcx.sess.opts.output_types.should_codegen() { @@ -129,12 +129,17 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, cnum: CrateNum) -> DefIdMap< tcx.symbol_name(Instance::mono(tcx, def_id.to_def_id())), export_level ); - (def_id.to_def_id(), export_level) + (def_id.to_def_id(), SymbolExportInfo { + level: export_level, + }) }) .collect(); if let Some(id) = tcx.proc_macro_decls_static(()) { - reachable_non_generics.insert(id.to_def_id(), SymbolExportLevel::C); + reachable_non_generics.insert( + id.to_def_id(), + SymbolExportInfo { level: SymbolExportLevel::C }, + ); } reachable_non_generics @@ -143,8 +148,8 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, cnum: CrateNum) -> DefIdMap< fn is_reachable_non_generic_provider_local(tcx: TyCtxt<'_>, def_id: DefId) -> bool { let export_threshold = threshold(tcx); - if let Some(&level) = tcx.reachable_non_generics(def_id.krate).get(&def_id) { - level.is_below_threshold(export_threshold) + if let Some(&info) = tcx.reachable_non_generics(def_id.krate).get(&def_id) { + info.level.is_below_threshold(export_threshold) } else { false } @@ -157,7 +162,7 @@ fn is_reachable_non_generic_provider_extern(tcx: TyCtxt<'_>, def_id: DefId) -> b fn exported_symbols_provider_local<'tcx>( tcx: TyCtxt<'tcx>, cnum: CrateNum, -) -> &'tcx [(ExportedSymbol<'tcx>, SymbolExportLevel)] { +) -> &'tcx [(ExportedSymbol<'tcx>, SymbolExportInfo)] { assert_eq!(cnum, LOCAL_CRATE); if !tcx.sess.opts.output_types.should_codegen() { @@ -167,13 +172,16 @@ fn exported_symbols_provider_local<'tcx>( let mut symbols: Vec<_> = tcx .reachable_non_generics(LOCAL_CRATE) .iter() - .map(|(&def_id, &level)| (ExportedSymbol::NonGeneric(def_id), level)) + .map(|(&def_id, &info)| (ExportedSymbol::NonGeneric(def_id), info)) .collect(); if tcx.entry_fn(()).is_some() { let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(tcx, "main")); - symbols.push((exported_symbol, SymbolExportLevel::C)); + symbols.push(( + exported_symbol, + SymbolExportInfo { level: SymbolExportLevel::C }, + )); } if tcx.allocator_kind(()).is_some() { @@ -181,7 +189,10 @@ fn exported_symbols_provider_local<'tcx>( let symbol_name = format!("__rust_{}", method.name); let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(tcx, &symbol_name)); - symbols.push((exported_symbol, SymbolExportLevel::Rust)); + symbols.push(( + exported_symbol, + SymbolExportInfo { level: SymbolExportLevel::Rust }, + )); } } @@ -194,7 +205,10 @@ fn exported_symbols_provider_local<'tcx>( symbols.extend(PROFILER_WEAK_SYMBOLS.iter().map(|sym| { let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(tcx, sym)); - (exported_symbol, SymbolExportLevel::C) + ( + exported_symbol, + SymbolExportInfo { level: SymbolExportLevel::C }, + ) })); } @@ -204,7 +218,10 @@ fn exported_symbols_provider_local<'tcx>( symbols.extend(MSAN_WEAK_SYMBOLS.iter().map(|sym| { let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(tcx, sym)); - (exported_symbol, SymbolExportLevel::C) + ( + exported_symbol, + SymbolExportInfo { level: SymbolExportLevel::C }, + ) })); } @@ -212,7 +229,10 @@ fn exported_symbols_provider_local<'tcx>( let symbol_name = metadata_symbol_name(tcx); let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(tcx, &symbol_name)); - symbols.push((exported_symbol, SymbolExportLevel::Rust)); + symbols.push(( + exported_symbol, + SymbolExportInfo { level: SymbolExportLevel::Rust }, + )); } if tcx.sess.opts.share_generics() && tcx.local_crate_exports_generics() { @@ -245,7 +265,12 @@ fn exported_symbols_provider_local<'tcx>( MonoItem::Fn(Instance { def: InstanceDef::Item(def), substs }) => { if substs.non_erasable_generics().next().is_some() { let symbol = ExportedSymbol::Generic(def.did, substs); - symbols.push((symbol, SymbolExportLevel::Rust)); + symbols.push(( + symbol, + SymbolExportInfo { + level: SymbolExportLevel::Rust, + }, + )); } } MonoItem::Fn(Instance { def: InstanceDef::DropGlue(_, Some(ty)), substs }) => { @@ -254,7 +279,12 @@ fn exported_symbols_provider_local<'tcx>( substs.non_erasable_generics().next(), Some(GenericArgKind::Type(ty)) ); - symbols.push((ExportedSymbol::DropGlue(ty), SymbolExportLevel::Rust)); + symbols.push(( + ExportedSymbol::DropGlue(ty), + SymbolExportInfo { + level: SymbolExportLevel::Rust, + }, + )); } _ => { // Any other symbols don't qualify for sharing diff --git a/compiler/rustc_codegen_ssa/src/back/write.rs b/compiler/rustc_codegen_ssa/src/back/write.rs index d4eaf6389df..7a6e9bfd2b7 100644 --- a/compiler/rustc_codegen_ssa/src/back/write.rs +++ b/compiler/rustc_codegen_ssa/src/back/write.rs @@ -23,7 +23,7 @@ use rustc_incremental::{ }; use rustc_metadata::EncodedMetadata; use rustc_middle::dep_graph::{WorkProduct, WorkProductId}; -use rustc_middle::middle::exported_symbols::SymbolExportLevel; +use rustc_middle::middle::exported_symbols::SymbolExportInfo; use rustc_middle::ty::TyCtxt; use rustc_session::cgu_reuse_tracker::CguReuseTracker; use rustc_session::config::{self, CrateType, Lto, OutputFilenames, OutputType}; @@ -304,7 +304,7 @@ pub type TargetMachineFactoryFn = Arc< + Sync, >; -pub type ExportedSymbols = FxHashMap>>; +pub type ExportedSymbols = FxHashMap>>; /// Additional resources used by optimize_and_codegen (not module specific) #[derive(Clone)] -- cgit 1.4.1-3-g733a5 From 773f533eae25129cea7241b74e54f26ce5eebb62 Mon Sep 17 00:00:00 2001 From: Gary Guo Date: Sat, 2 Apr 2022 22:54:51 +0100 Subject: Synthesis object file for `#[used]` and exported symbols --- compiler/rustc_codegen_ssa/src/back/link.rs | 69 ++++++++++++++++++++++ compiler/rustc_codegen_ssa/src/back/linker.rs | 46 +++++++++++++++ compiler/rustc_codegen_ssa/src/back/metadata.rs | 2 +- .../rustc_codegen_ssa/src/back/symbol_export.rs | 54 ++++++++++++++--- compiler/rustc_codegen_ssa/src/base.rs | 7 +++ compiler/rustc_codegen_ssa/src/lib.rs | 2 + .../rustc_middle/src/middle/exported_symbols.rs | 10 ++++ 7 files changed, 182 insertions(+), 8 deletions(-) (limited to 'compiler/rustc_codegen_ssa/src') diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs index 548ae0e411d..45ae5ffc513 100644 --- a/compiler/rustc_codegen_ssa/src/back/link.rs +++ b/compiler/rustc_codegen_ssa/src/back/link.rs @@ -7,6 +7,7 @@ use rustc_errors::{ErrorGuaranteed, Handler}; use rustc_fs_util::fix_windows_verbatim_for_gcc; use rustc_hir::def_id::CrateNum; use rustc_middle::middle::dependency_format::Linkage; +use rustc_middle::middle::exported_symbols::SymbolExportKind; use rustc_session::config::{self, CFGuard, CrateType, DebugInfo, LdImpl, Strip}; use rustc_session::config::{OutputFilenames, OutputType, PrintRequest, SplitDwarfKind}; use rustc_session::cstore::DllImport; @@ -1654,6 +1655,67 @@ fn add_post_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor } } +/// Add a synthetic object file that contains reference to all symbols that we want to expose to +/// the linker. +/// +/// Background: we implement rlibs as static library (archives). Linkers treat archives +/// differently from object files: all object files participate in linking, while archives will +/// only participate in linking if they can satisfy at least one undefined reference (version +/// scripts doesn't count). This causes `#[no_mangle]` or `#[used]` items to be ignored by the +/// 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 +/// 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` +/// from removing them, and this is especially problematic for embedded programming where every +/// byte counts. +/// +/// This method creates a synthetic object file, which contains undefined references to all symbols +/// 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. +fn add_linked_symbol_object( + cmd: &mut dyn Linker, + sess: &Session, + tmpdir: &Path, + symbols: &[(String, SymbolExportKind)], +) { + if symbols.is_empty() { + return; + } + + let Some(mut file) = super::metadata::create_object_file(sess) else { + return; + }; + + for (sym, kind) in symbols.iter() { + file.add_symbol(object::write::Symbol { + name: sym.clone().into(), + value: 0, + size: 0, + kind: match kind { + SymbolExportKind::Text => object::SymbolKind::Text, + SymbolExportKind::Data => object::SymbolKind::Data, + SymbolExportKind::Tls => object::SymbolKind::Tls, + }, + scope: object::SymbolScope::Unknown, + weak: false, + section: object::write::SymbolSection::Undefined, + flags: object::SymbolFlags::None, + }); + } + + let path = tmpdir.join("symbols.o"); + let result = std::fs::write(&path, file.write().unwrap()); + if let Err(e) = result { + sess.fatal(&format!("failed to write {}: {}", path.display(), e)); + } + cmd.add_object(&path); +} + /// Add object files containing code from the current crate. fn add_local_crate_regular_objects(cmd: &mut dyn Linker, codegen_results: &CodegenResults) { for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) { @@ -1794,6 +1856,13 @@ fn linker_with_args<'a, B: ArchiveBuilder<'a>>( // Pre-link CRT objects. add_pre_link_objects(cmd, sess, link_output_kind, crt_objects_fallback); + add_linked_symbol_object( + cmd, + sess, + tmpdir, + &codegen_results.crate_info.linked_symbols[&crate_type], + ); + // Sanitizer libraries. add_sanitizer_libraries(sess, crate_type, cmd); diff --git a/compiler/rustc_codegen_ssa/src/back/linker.rs b/compiler/rustc_codegen_ssa/src/back/linker.rs index a90b8a62c62..044dd9556fe 100644 --- a/compiler/rustc_codegen_ssa/src/back/linker.rs +++ b/compiler/rustc_codegen_ssa/src/back/linker.rs @@ -12,6 +12,7 @@ use std::{env, mem, str}; use rustc_hir::def_id::{CrateNum, LOCAL_CRATE}; use rustc_middle::middle::dependency_format::Linkage; +use rustc_middle::middle::exported_symbols::SymbolExportKind; use rustc_middle::ty::TyCtxt; use rustc_serialize::{json, Encoder}; use rustc_session::config::{self, CrateType, DebugInfo, LinkerPluginLto, Lto, OptLevel, Strip}; @@ -1557,6 +1558,51 @@ pub(crate) fn exported_symbols(tcx: TyCtxt<'_>, crate_type: CrateType) -> Vec, + crate_type: CrateType, +) -> Vec<(String, SymbolExportKind)> { + match crate_type { + CrateType::Executable | CrateType::Cdylib => (), + CrateType::Staticlib | CrateType::ProcMacro | CrateType::Rlib | CrateType::Dylib => { + return Vec::new(); + } + } + + let mut symbols = Vec::new(); + + let export_threshold = symbol_export::crates_export_threshold(&[crate_type]); + for &(symbol, info) in tcx.exported_symbols(LOCAL_CRATE).iter() { + if info.level.is_below_threshold(export_threshold) || info.used { + symbols.push(( + symbol_export::symbol_name_for_instance_in_crate(tcx, symbol, LOCAL_CRATE), + info.kind, + )); + } + } + + let formats = tcx.dependency_formats(()); + let deps = formats.iter().find_map(|(t, list)| (*t == crate_type).then_some(list)).unwrap(); + + for (index, dep_format) in deps.iter().enumerate() { + let cnum = CrateNum::new(index + 1); + // For each dependency that we are linking to statically ... + if *dep_format == Linkage::Static { + // ... we add its symbol list to our export list. + for &(symbol, info) in tcx.exported_symbols(cnum).iter() { + if info.level.is_below_threshold(export_threshold) || info.used { + symbols.push(( + symbol_export::symbol_name_for_instance_in_crate(tcx, symbol, cnum), + info.kind, + )); + } + } + } + } + + symbols +} + /// Much simplified and explicit CLI for the NVPTX linker. The linker operates /// with bitcode and uses LLVM backend to generate a PTX assembly. pub struct PtxLinker<'a> { diff --git a/compiler/rustc_codegen_ssa/src/back/metadata.rs b/compiler/rustc_codegen_ssa/src/back/metadata.rs index c52269805c4..2e422728056 100644 --- a/compiler/rustc_codegen_ssa/src/back/metadata.rs +++ b/compiler/rustc_codegen_ssa/src/back/metadata.rs @@ -94,7 +94,7 @@ fn search_for_metadata<'a>( .map_err(|e| format!("failed to read {} section in '{}': {}", section, path.display(), e)) } -fn create_object_file(sess: &Session) -> Option> { +pub(crate) fn create_object_file(sess: &Session) -> Option> { let endianness = match sess.target.options.endian { Endian::Little => Endianness::Little, Endian::Big => Endianness::Big, diff --git a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs index e14ebe3ae48..56159cc2e08 100644 --- a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs +++ b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs @@ -9,7 +9,7 @@ use rustc_hir::Node; use rustc_index::vec::IndexVec; use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags; use rustc_middle::middle::exported_symbols::{ - metadata_symbol_name, ExportedSymbol, SymbolExportInfo, SymbolExportLevel, + metadata_symbol_name, ExportedSymbol, SymbolExportInfo, SymbolExportKind, SymbolExportLevel, }; use rustc_middle::ty::query::{ExternProviders, Providers}; use rustc_middle::ty::subst::{GenericArgKind, SubstsRef}; @@ -124,6 +124,7 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, cnum: CrateNum) -> DefIdMap< } else { symbol_export_level(tcx, def_id.to_def_id()) }; + let codegen_attrs = tcx.codegen_fn_attrs(def_id.to_def_id()); debug!( "EXPORTED SYMBOL (local): {} ({:?})", tcx.symbol_name(Instance::mono(tcx, def_id.to_def_id())), @@ -131,6 +132,17 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, cnum: CrateNum) -> DefIdMap< ); (def_id.to_def_id(), SymbolExportInfo { level: export_level, + kind: if tcx.is_static(def_id.to_def_id()) { + if codegen_attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) { + SymbolExportKind::Tls + } else { + SymbolExportKind::Data + } + } else { + SymbolExportKind::Text + }, + used: codegen_attrs.flags.contains(CodegenFnAttrFlags::USED) + || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER), }) }) .collect(); @@ -138,7 +150,11 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, cnum: CrateNum) -> DefIdMap< if let Some(id) = tcx.proc_macro_decls_static(()) { reachable_non_generics.insert( id.to_def_id(), - SymbolExportInfo { level: SymbolExportLevel::C }, + SymbolExportInfo { + level: SymbolExportLevel::C, + kind: SymbolExportKind::Data, + used: false, + }, ); } @@ -180,7 +196,11 @@ fn exported_symbols_provider_local<'tcx>( symbols.push(( exported_symbol, - SymbolExportInfo { level: SymbolExportLevel::C }, + SymbolExportInfo { + level: SymbolExportLevel::C, + kind: SymbolExportKind::Text, + used: false, + }, )); } @@ -191,7 +211,11 @@ fn exported_symbols_provider_local<'tcx>( symbols.push(( exported_symbol, - SymbolExportInfo { level: SymbolExportLevel::Rust }, + SymbolExportInfo { + level: SymbolExportLevel::Rust, + kind: SymbolExportKind::Text, + used: false, + }, )); } } @@ -207,7 +231,11 @@ fn exported_symbols_provider_local<'tcx>( let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(tcx, sym)); ( exported_symbol, - SymbolExportInfo { level: SymbolExportLevel::C }, + SymbolExportInfo { + level: SymbolExportLevel::C, + kind: SymbolExportKind::Data, + used: false, + }, ) })); } @@ -220,7 +248,11 @@ fn exported_symbols_provider_local<'tcx>( let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(tcx, sym)); ( exported_symbol, - SymbolExportInfo { level: SymbolExportLevel::C }, + SymbolExportInfo { + level: SymbolExportLevel::C, + kind: SymbolExportKind::Data, + used: false, + }, ) })); } @@ -231,7 +263,11 @@ fn exported_symbols_provider_local<'tcx>( symbols.push(( exported_symbol, - SymbolExportInfo { level: SymbolExportLevel::Rust }, + SymbolExportInfo { + level: SymbolExportLevel::Rust, + kind: SymbolExportKind::Data, + used: false, + }, )); } @@ -269,6 +305,8 @@ fn exported_symbols_provider_local<'tcx>( symbol, SymbolExportInfo { level: SymbolExportLevel::Rust, + kind: SymbolExportKind::Text, + used: false, }, )); } @@ -283,6 +321,8 @@ fn exported_symbols_provider_local<'tcx>( ExportedSymbol::DropGlue(ty), SymbolExportInfo { level: SymbolExportLevel::Rust, + kind: SymbolExportKind::Text, + used: false, }, )); } diff --git a/compiler/rustc_codegen_ssa/src/base.rs b/compiler/rustc_codegen_ssa/src/base.rs index 01056024805..5a1d0208842 100644 --- a/compiler/rustc_codegen_ssa/src/base.rs +++ b/compiler/rustc_codegen_ssa/src/base.rs @@ -801,6 +801,12 @@ impl CrateInfo { .iter() .map(|&c| (c, crate::back::linker::exported_symbols(tcx, c))) .collect(); + let linked_symbols = tcx + .sess + .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 = tcx.sess.first_attr_value_str_by_name(crate_attrs, sym::windows_subsystem); @@ -834,6 +840,7 @@ impl CrateInfo { let mut info = CrateInfo { target_cpu, exported_symbols, + linked_symbols, local_crate_name, compiler_builtins: None, profiler_runtime: None, diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs index 6cf6be79a86..f3d5bb4bc62 100644 --- a/compiler/rustc_codegen_ssa/src/lib.rs +++ b/compiler/rustc_codegen_ssa/src/lib.rs @@ -28,6 +28,7 @@ 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; use rustc_middle::ty::query::{ExternProviders, Providers}; use rustc_session::config::{CrateType, OutputFilenames, OutputType, RUST_CGU_EXT}; use rustc_session::cstore::{self, CrateSource}; @@ -140,6 +141,7 @@ impl From<&cstore::NativeLib> for NativeLib { pub struct CrateInfo { pub target_cpu: String, pub exported_symbols: FxHashMap>, + pub linked_symbols: FxHashMap>, pub local_crate_name: Symbol, pub compiler_builtins: Option, pub profiler_runtime: Option, diff --git a/compiler/rustc_middle/src/middle/exported_symbols.rs b/compiler/rustc_middle/src/middle/exported_symbols.rs index a605e6dfdc1..631fd09ec4c 100644 --- a/compiler/rustc_middle/src/middle/exported_symbols.rs +++ b/compiler/rustc_middle/src/middle/exported_symbols.rs @@ -21,11 +21,21 @@ impl SymbolExportLevel { } } +/// Kind of exported symbols. +#[derive(Eq, PartialEq, Debug, Copy, Clone, Encodable, Decodable, HashStable)] +pub enum SymbolExportKind { + Text, + Data, + Tls, +} + /// The `SymbolExportInfo` of a symbols specifies symbol-related information /// that is relevant to code generation and linking. #[derive(Eq, PartialEq, Debug, Copy, Clone, TyEncodable, TyDecodable, HashStable)] pub struct SymbolExportInfo { pub level: SymbolExportLevel, + pub kind: SymbolExportKind, + pub used: bool, } #[derive(Eq, PartialEq, Debug, Copy, Clone, TyEncodable, TyDecodable, HashStable)] -- cgit 1.4.1-3-g733a5 From c475117ffb526a7c45c3b59710bd9dcdc38982af Mon Sep 17 00:00:00 2001 From: Gary Guo Date: Sun, 10 Apr 2022 02:16:12 +0100 Subject: Refactor exported_symbols and linked_symbols for code reuse --- compiler/rustc_codegen_ssa/src/back/linker.rs | 70 ++++++++++----------------- 1 file changed, 26 insertions(+), 44 deletions(-) (limited to 'compiler/rustc_codegen_ssa/src') diff --git a/compiler/rustc_codegen_ssa/src/back/linker.rs b/compiler/rustc_codegen_ssa/src/back/linker.rs index 044dd9556fe..fce34023250 100644 --- a/compiler/rustc_codegen_ssa/src/back/linker.rs +++ b/compiler/rustc_codegen_ssa/src/back/linker.rs @@ -12,7 +12,7 @@ use std::{env, mem, str}; use rustc_hir::def_id::{CrateNum, LOCAL_CRATE}; use rustc_middle::middle::dependency_format::Linkage; -use rustc_middle::middle::exported_symbols::SymbolExportKind; +use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo, SymbolExportKind}; use rustc_middle::ty::TyCtxt; use rustc_serialize::{json, Encoder}; use rustc_session::config::{self, CrateType, DebugInfo, LinkerPluginLto, Lto, OptLevel, Strip}; @@ -1519,22 +1519,13 @@ impl<'a> L4Bender<'a> { } } -pub(crate) fn exported_symbols(tcx: TyCtxt<'_>, crate_type: CrateType) -> Vec { - if let Some(ref exports) = tcx.sess.target.override_export_symbols { - return exports.clone(); - } - - let mut symbols = Vec::new(); - - let export_threshold = symbol_export::crates_export_threshold(&[crate_type]); +fn for_each_exported_symbols_include_dep<'tcx>( + tcx: TyCtxt<'tcx>, + crate_type: CrateType, + mut callback: impl FnMut(ExportedSymbol<'tcx>, SymbolExportInfo, CrateNum), +) { for &(symbol, info) in tcx.exported_symbols(LOCAL_CRATE).iter() { - if info.level.is_below_threshold(export_threshold) { - symbols.push(symbol_export::symbol_name_for_instance_in_crate( - tcx, - symbol, - LOCAL_CRATE, - )); - } + callback(symbol, info, LOCAL_CRATE); } let formats = tcx.dependency_formats(()); @@ -1544,16 +1535,26 @@ pub(crate) fn exported_symbols(tcx: TyCtxt<'_>, crate_type: CrateType) -> Vec, crate_type: CrateType) -> Vec { + if let Some(ref exports) = tcx.sess.target.override_export_symbols { + return exports.clone(); + } + + let mut symbols = Vec::new(); + + let export_threshold = symbol_export::crates_export_threshold(&[crate_type]); + for_each_exported_symbols_include_dep(tcx, crate_type, |symbol, info, cnum| { + if info.level.is_below_threshold(export_threshold) { + symbols.push(symbol_export::symbol_name_for_instance_in_crate(tcx, symbol, cnum)); + } + }); symbols } @@ -1572,33 +1573,14 @@ pub(crate) fn linked_symbols( let mut symbols = Vec::new(); let export_threshold = symbol_export::crates_export_threshold(&[crate_type]); - for &(symbol, info) in tcx.exported_symbols(LOCAL_CRATE).iter() { + for_each_exported_symbols_include_dep(tcx, crate_type, |symbol, info, cnum| { if info.level.is_below_threshold(export_threshold) || info.used { symbols.push(( - symbol_export::symbol_name_for_instance_in_crate(tcx, symbol, LOCAL_CRATE), + symbol_export::symbol_name_for_instance_in_crate(tcx, symbol, cnum), info.kind, )); } - } - - let formats = tcx.dependency_formats(()); - let deps = formats.iter().find_map(|(t, list)| (*t == crate_type).then_some(list)).unwrap(); - - for (index, dep_format) in deps.iter().enumerate() { - let cnum = CrateNum::new(index + 1); - // For each dependency that we are linking to statically ... - if *dep_format == Linkage::Static { - // ... we add its symbol list to our export list. - for &(symbol, info) in tcx.exported_symbols(cnum).iter() { - if info.level.is_below_threshold(export_threshold) || info.used { - symbols.push(( - symbol_export::symbol_name_for_instance_in_crate(tcx, symbol, cnum), - info.kind, - )); - } - } - } - } + }); symbols } -- cgit 1.4.1-3-g733a5 From e2fdb84df7c967e840a576fab86affab1e63d9fd Mon Sep 17 00:00:00 2001 From: Gary Guo Date: Mon, 18 Apr 2022 02:58:33 +0100 Subject: Conditionally export msan symbols only if they are defined * `__msan_keep_going` is defined when `-Zsanitizer-recover=memory`. * `__msan_track_origins` is defined when `-Zsanitizer-memory-track-origins`. --- compiler/rustc_codegen_ssa/src/back/symbol_export.rs | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'compiler/rustc_codegen_ssa/src') diff --git a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs index 56159cc2e08..2fa6778cca4 100644 --- a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs +++ b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs @@ -241,10 +241,18 @@ fn exported_symbols_provider_local<'tcx>( } if tcx.sess.opts.debugging_opts.sanitizer.contains(SanitizerSet::MEMORY) { + let mut msan_weak_symbols = Vec::new(); + // Similar to profiling, preserve weak msan symbol during LTO. - const MSAN_WEAK_SYMBOLS: [&str; 2] = ["__msan_track_origins", "__msan_keep_going"]; + if tcx.sess.opts.debugging_opts.sanitizer_recover.contains(SanitizerSet::MEMORY) { + msan_weak_symbols.push("__msan_keep_going"); + } + + if tcx.sess.opts.debugging_opts.sanitizer_memory_track_origins != 0 { + msan_weak_symbols.push("__msan_track_origins"); + } - symbols.extend(MSAN_WEAK_SYMBOLS.iter().map(|sym| { + symbols.extend(msan_weak_symbols.into_iter().map(|sym| { let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(tcx, sym)); ( exported_symbol, -- cgit 1.4.1-3-g733a5 From 9ebeb284b588c0549dca2169227cabb7417825be Mon Sep 17 00:00:00 2001 From: Gary Guo Date: Sun, 24 Apr 2022 13:13:41 +0100 Subject: Fix MSVC hang issue --- compiler/rustc_codegen_ssa/src/back/link.rs | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'compiler/rustc_codegen_ssa/src') diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs index 45ae5ffc513..2dc3f4e8f3a 100644 --- a/compiler/rustc_codegen_ssa/src/back/link.rs +++ b/compiler/rustc_codegen_ssa/src/back/link.rs @@ -1691,6 +1691,12 @@ fn add_linked_symbol_object( return; }; + // NOTE(nbdd0121): MSVC will hang if the input object file contains no sections, + // so add an empty section. + if file.format() == object::BinaryFormat::Coff { + file.add_section(Vec::new(), ".text".into(), object::SectionKind::Text); + } + for (sym, kind) in symbols.iter() { file.add_symbol(object::write::Symbol { name: sym.clone().into(), -- cgit 1.4.1-3-g733a5 From 6f9b2b32476dbd3453e296bea54726d469e471c0 Mon Sep 17 00:00:00 2001 From: Gary Guo Date: Mon, 25 Apr 2022 14:06:30 +0100 Subject: Stop exporting rust_eh_personality and friends from cdylib --- .../rustc_codegen_ssa/src/back/symbol_export.rs | 24 ++++++++-------------- 1 file changed, 9 insertions(+), 15 deletions(-) (limited to 'compiler/rustc_codegen_ssa/src') diff --git a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs index 2fa6778cca4..10d70b11746 100644 --- a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs +++ b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs @@ -105,24 +105,18 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, cnum: CrateNum) -> DefIdMap< } }) .map(|def_id| { - let export_level = if special_runtime_crate { + let (export_level, used) = if special_runtime_crate { let name = tcx.symbol_name(Instance::mono(tcx, def_id.to_def_id())).name; - // We can probably do better here by just ensuring that - // it has hidden visibility rather than public - // visibility, as this is primarily here to ensure it's - // not stripped during LTO. - // - // In general though we won't link right if these - // symbols are stripped, and LTO currently strips them. - match name { + // We won't link right if these symbols are stripped during LTO. + let used = match name { "rust_eh_personality" | "rust_eh_register_frames" - | "rust_eh_unregister_frames" => - SymbolExportLevel::C, - _ => SymbolExportLevel::Rust, - } + | "rust_eh_unregister_frames" => true, + _ => false, + }; + (SymbolExportLevel::Rust, used) } else { - symbol_export_level(tcx, def_id.to_def_id()) + (symbol_export_level(tcx, def_id.to_def_id()), false) }; let codegen_attrs = tcx.codegen_fn_attrs(def_id.to_def_id()); debug!( @@ -142,7 +136,7 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, cnum: CrateNum) -> DefIdMap< SymbolExportKind::Text }, used: codegen_attrs.flags.contains(CodegenFnAttrFlags::USED) - || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER), + || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER) || used, }) }) .collect(); -- cgit 1.4.1-3-g733a5