From d76cff3f06f4de2e760eee3130c8a393fa4a124f Mon Sep 17 00:00:00 2001 From: bjorn3 <17426603+bjorn3@users.noreply.github.com> Date: Thu, 28 Aug 2025 17:36:46 +0000 Subject: [PATCH 1/2] Only export the sanitizer symbols for LTO and move export code to cg_llvm 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. --- compiler/rustc_codegen_llvm/src/back/lto.rs | 28 +++++++++++ .../src/back/symbol_export.rs | 49 +------------------ 2 files changed, 29 insertions(+), 48 deletions(-) diff --git a/compiler/rustc_codegen_llvm/src/back/lto.rs b/compiler/rustc_codegen_llvm/src/back/lto.rs index d85f432702cc5..551a448d97cc1 100644 --- a/compiler/rustc_codegen_llvm/src/back/lto.rs +++ b/compiler/rustc_codegen_llvm/src/back/lto.rs @@ -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::>(); + 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. diff --git a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs index 13419bcb22c73..d8a1480e911fe 100644 --- a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs +++ b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs @@ -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)); From 23e72ab41e27842eae0d60a6f4750c5151aabcbc Mon Sep 17 00:00:00 2001 From: bjorn3 <17426603+bjorn3@users.noreply.github.com> Date: Thu, 28 Aug 2025 18:05:47 +0000 Subject: [PATCH 2/2] Move ___asan_globals_registered export All other sanitizer symbols are handled in prepare_lto already. --- compiler/rustc_codegen_llvm/src/back/lto.rs | 4 ++++ compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp | 6 ------ 2 files changed, 4 insertions(+), 6 deletions(-) diff --git a/compiler/rustc_codegen_llvm/src/back/lto.rs b/compiler/rustc_codegen_llvm/src/back/lto.rs index 551a448d97cc1..fc38c4f3e5138 100644 --- a/compiler/rustc_codegen_llvm/src/back/lto.rs +++ b/compiler/rustc_codegen_llvm/src/back/lto.rs @@ -70,6 +70,10 @@ fn prepare_lto( symbols_below_threshold.extend(msan_weak_symbols.into_iter().map(|sym| sym.to_owned())); } + // Preserve LLVM-injected, ASAN-related symbols. + // See also https://github.com/rust-lang/rust/issues/113404. + symbols_below_threshold.push(c"___asan_globals_registered".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. diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp index 8c34052770e61..dd49232581497 100644 --- a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp +++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp @@ -1226,12 +1226,6 @@ extern "C" void LLVMRustPrintPasses() { extern "C" void LLVMRustRunRestrictionPass(LLVMModuleRef M, char **Symbols, size_t Len) { auto PreserveFunctions = [=](const GlobalValue &GV) { - // Preserve LLVM-injected, ASAN-related symbols. - // See also https://github.com/rust-lang/rust/issues/113404. - if (GV.getName() == "___asan_globals_registered") { - return true; - } - // Preserve symbols exported from Rust modules. for (size_t I = 0; I < Len; I++) { if (GV.getName() == Symbols[I]) {