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Only export the sanitizer symbols for LTO and move export code to cg_llvm

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Don't export them from cdylibs. There is no need to do so and it
complicates exported_non_generic_symbols. In addition the GCC backend
likely uses different symbols and may potentially not even need us to
explicitly tell it to export the symbols it needs.
This commit is contained in:
bjorn3 2025-08-28 17:36:46 +00:00
parent 43a216604a
commit d76cff3f06
2 changed files with 29 additions and 48 deletions
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28
compiler/rustc_codegen_llvm/src/back/lto.rs
View file

@ -15,6 +15,7 @@ use rustc_codegen_ssa::{ModuleCodegen, ModuleKind, looks_like_rust_object_file};
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::memmap::Mmap;
use rustc_errors::DiagCtxtHandle;
use rustc_hir::attrs::SanitizerSet;
use rustc_middle::bug;
use rustc_middle::dep_graph::WorkProduct;
use rustc_session::config::{self, Lto};
@ -42,6 +43,33 @@ fn prepare_lto(
.map(|symbol| CString::new(symbol.to_owned()).unwrap())
.collect::<Vec<CString>>();
if cgcx.regular_module_config.instrument_coverage
|| cgcx.regular_module_config.pgo_gen.enabled()
{
// These are weak symbols that point to the profile version and the
// profile name, which need to be treated as exported so LTO doesn't nix
// them.
const PROFILER_WEAK_SYMBOLS: [&CStr; 2] =
[c"__llvm_profile_raw_version", c"__llvm_profile_filename"];
symbols_below_threshold.extend(PROFILER_WEAK_SYMBOLS.iter().map(|&sym| sym.to_owned()));
}
if cgcx.regular_module_config.sanitizer.contains(SanitizerSet::MEMORY) {
let mut msan_weak_symbols = Vec::new();
// Similar to profiling, preserve weak msan symbol during LTO.
if cgcx.regular_module_config.sanitizer_recover.contains(SanitizerSet::MEMORY) {
msan_weak_symbols.push(c"__msan_keep_going");
}
if cgcx.regular_module_config.sanitizer_memory_track_origins != 0 {
msan_weak_symbols.push(c"__msan_track_origins");
}
symbols_below_threshold.extend(msan_weak_symbols.into_iter().map(|sym| sym.to_owned()));
}
// __llvm_profile_counter_bias is pulled in at link time by an undefined reference to
// __llvm_profile_runtime, therefore we won't know until link time if this symbol
// should have default visibility.

49
compiler/rustc_codegen_ssa/src/back/symbol_export.rs
View file

@ -15,7 +15,7 @@ use rustc_middle::ty::{self, GenericArgKind, GenericArgsRef, Instance, SymbolNam
use rustc_middle::util::Providers;
use rustc_session::config::{CrateType, OomStrategy};
use rustc_symbol_mangling::mangle_internal_symbol;
use rustc_target::spec::{SanitizerSet, TlsModel};
use rustc_target::spec::TlsModel;
use tracing::debug;
use crate::base::allocator_kind_for_codegen;
@ -242,53 +242,6 @@ fn exported_non_generic_symbols_provider_local<'tcx>(
}
}
if tcx.sess.instrument_coverage() || tcx.sess.opts.cg.profile_generate.enabled() {
// These are weak symbols that point to the profile version and the
// profile name, which need to be treated as exported so LTO doesn't nix
// them.
const PROFILER_WEAK_SYMBOLS: [&str; 2] =
["__llvm_profile_raw_version", "__llvm_profile_filename"];
symbols.extend(PROFILER_WEAK_SYMBOLS.iter().map(|sym| {
let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(tcx, sym));
(
exported_symbol,
SymbolExportInfo {
level: SymbolExportLevel::C,
kind: SymbolExportKind::Data,
used: false,
rustc_std_internal_symbol: false,
},
)
}));
}
if tcx.sess.opts.unstable_opts.sanitizer.contains(SanitizerSet::MEMORY) {
let mut msan_weak_symbols = Vec::new();
// Similar to profiling, preserve weak msan symbol during LTO.
if tcx.sess.opts.unstable_opts.sanitizer_recover.contains(SanitizerSet::MEMORY) {
msan_weak_symbols.push("__msan_keep_going");
}
if tcx.sess.opts.unstable_opts.sanitizer_memory_track_origins != 0 {
msan_weak_symbols.push("__msan_track_origins");
}
symbols.extend(msan_weak_symbols.into_iter().map(|sym| {
let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(tcx, sym));
(
exported_symbol,
SymbolExportInfo {
level: SymbolExportLevel::C,
kind: SymbolExportKind::Data,
used: false,
rustc_std_internal_symbol: false,
},
)
}));
}
// Sort so we get a stable incr. comp. hash.
symbols.sort_by_cached_key(|s| s.0.symbol_name_for_local_instance(tcx));