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Remove a special case and move another one out of reachable_non_generics #148247

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Merged
merged 2 commits into from
Nov 3, 2025
+11 −16
Merged

Remove a special case and move another one out of reachable_non_generics #148247

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964d3af
Move a special case for rust_eh_personality from reachable_non_generi…
bjorn3 Oct 29, 2025
e8d88c0
Remove special case for the panic runtime from reachable_non_generics
bjorn3 Oct 29, 2025
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3 changes: 3 additions & 0 deletions compiler/rustc_codegen_llvm/src/back/lto.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,9 @@ fn prepare_lto(
// should have default visibility.
symbols_below_threshold.push(c"__llvm_profile_counter_bias".to_owned());

// LTO seems to discard this otherwise under certain circumstances.
symbols_below_threshold.push(c"rust_eh_personality".to_owned());

// If we're performing LTO for the entire crate graph, then for each of our
// upstream dependencies, find the corresponding rlib and load the bitcode
// from the archive.
Expand Down
24 changes: 8 additions & 16 deletions compiler/rustc_codegen_ssa/src/back/symbol_export.rs
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Expand Up @@ -51,15 +51,7 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, _: LocalCrate) -> DefIdMap<S
return Default::default();
}

// Check to see if this crate is a "special runtime crate". These
// crates, implementation details of the standard library, typically
// have a bunch of `pub extern` and `#[no_mangle]` functions as the
// ABI between them. We don't want their symbols to have a `C`
// export level, however, as they're just implementation details.
// Down below we'll hardwire all of the symbols to the `Rust` export
// level instead.
let special_runtime_crate =
tcx.is_panic_runtime(LOCAL_CRATE) || tcx.is_compiler_builtins(LOCAL_CRATE);
let is_compiler_builtins = tcx.is_compiler_builtins(LOCAL_CRATE);

let mut reachable_non_generics: DefIdMap<_> = tcx
.reachable_set(())
Expand Down Expand Up @@ -104,11 +96,12 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, _: LocalCrate) -> DefIdMap<S
if tcx.cross_crate_inlinable(def_id) { None } else { Some(def_id) }
})
.map(|def_id| {
// We won't link right if this symbol is stripped during LTO.
let name = tcx.symbol_name(Instance::mono(tcx, def_id.to_def_id())).name;
let used = name == "rust_eh_personality";

let export_level = if special_runtime_crate {
let export_level = if is_compiler_builtins {
// We don't want to export compiler-builtins symbols from any
// dylibs, even rust dylibs. Unlike all other crates it gets
// duplicated in every linker invocation and it may otherwise
// unintentionally override definitions of these symbols by
// libgcc or compiler-rt for C code.
SymbolExportLevel::Rust
} else {
symbol_export_level(tcx, def_id.to_def_id())
Expand All @@ -131,8 +124,7 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, _: LocalCrate) -> DefIdMap<S
SymbolExportKind::Text
},
used: codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER)
|| codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER)
|| used,
|| codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER),
rustc_std_internal_symbol: codegen_attrs
.flags
.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL),
Expand Down
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