diff options
Diffstat (limited to 'compiler/rustc_symbol_mangling/src/lib.rs')
| -rw-r--r-- | compiler/rustc_symbol_mangling/src/lib.rs | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/compiler/rustc_symbol_mangling/src/lib.rs b/compiler/rustc_symbol_mangling/src/lib.rs index c4558b5ce8b..c9b15151a2c 100644 --- a/compiler/rustc_symbol_mangling/src/lib.rs +++ b/compiler/rustc_symbol_mangling/src/lib.rs @@ -112,6 +112,8 @@ mod v0; pub mod errors; pub mod test; +pub use v0::mangle_internal_symbol; + /// This function computes the symbol name for the given `instance` and the /// given instantiating crate. That is, if you know that instance X is /// instantiated in crate Y, this is the symbol name this instance would have. @@ -183,6 +185,39 @@ fn compute_symbol_name<'tcx>( CodegenFnAttrs::EMPTY }; + if attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) { + // Items marked as #[rustc_std_internal_symbol] need to have a fixed + // symbol name because it is used to import items from another crate + // without a direct dependency. As such it is not possible to look up + // the mangled name for the `Instance` from the crate metadata of the + // defining crate. + // Weak lang items automatically get #[rustc_std_internal_symbol] + // applied by the code computing the CodegenFnAttrs. + // We are mangling all #[rustc_std_internal_symbol] items that don't + // also have #[no_mangle] as a combination of the rustc version and the + // unmangled linkage name. This is to ensure that if we link against a + // staticlib compiled by a different rustc version, we don't get symbol + // conflicts or even UB due to a different implementation/ABI. Rust + // staticlibs currently export all symbols, including those that are + // hidden in cdylibs. + // We are using the v0 symbol mangling scheme here as we need to be + // consistent across all crates and in some contexts the legacy symbol + // mangling scheme can't be used. For example both the GCC backend and + // Rust-for-Linux don't support some of the characters used by the + // legacy symbol mangling scheme. + let name = if tcx.is_foreign_item(def_id) { + if let Some(name) = attrs.link_name { name } else { tcx.item_name(def_id) } + } else { + if let Some(name) = attrs.export_name { name } else { tcx.item_name(def_id) } + }; + + if attrs.flags.contains(CodegenFnAttrFlags::NO_MANGLE) { + return name.to_string(); + } else { + return v0::mangle_internal_symbol(tcx, name.as_str()); + } + } + // Foreign items by default use no mangling for their symbol name. There's a // few exceptions to this rule though: // @@ -198,6 +233,8 @@ fn compute_symbol_name<'tcx>( // is present we mangle everything on wasm because the demangled form will // show up in the `wasm-import-name` custom attribute in LLVM IR. // + // * `#[rustc_std_internal_symbol]` mangles the symbol name in a special way + // both for exports and imports through foreign items. This is handled above. // [1]: https://bugs.llvm.org/show_bug.cgi?id=44316 if tcx.is_foreign_item(def_id) && (!tcx.sess.target.is_like_wasm |