Skip to content

Commit

Permalink
Auto merge of #96444 - nbdd0121:used2, r=petrochenkov
Browse files Browse the repository at this point in the history
Use decorated names for linked_symbols on Windows

Fix #96423

r? `@petrochenkov`
  • Loading branch information
bors committed Apr 29, 2022
2 parents ddb7fbe + 4f9acb2 commit 5560c51
Show file tree
Hide file tree
Showing 5 changed files with 90 additions and 2 deletions.
4 changes: 4 additions & 0 deletions compiler/rustc_codegen_ssa/src/back/link.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1696,6 +1696,10 @@ fn add_linked_symbol_object(
// so add an empty section.
if file.format() == object::BinaryFormat::Coff {
file.add_section(Vec::new(), ".text".into(), object::SectionKind::Text);

// We handle the name decoration of COFF targets in `symbol_export.rs`, so disable the
// default mangler in `object` crate.
file.set_mangling(object::write::Mangling::None);
}

for (sym, kind) in symbols.iter() {
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_codegen_ssa/src/back/linker.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1576,7 +1576,7 @@ pub(crate) fn linked_symbols(
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, cnum),
symbol_export::linking_symbol_name_for_instance_in_crate(tcx, symbol, cnum),
info.kind,
));
}
Expand Down
72 changes: 71 additions & 1 deletion compiler/rustc_codegen_ssa/src/back/symbol_export.rs
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ use rustc_middle::middle::exported_symbols::{
use rustc_middle::ty::query::{ExternProviders, Providers};
use rustc_middle::ty::subst::{GenericArgKind, SubstsRef};
use rustc_middle::ty::Instance;
use rustc_middle::ty::{SymbolName, TyCtxt};
use rustc_middle::ty::{self, SymbolName, TyCtxt};
use rustc_session::config::CrateType;
use rustc_target::spec::SanitizerSet;

Expand Down Expand Up @@ -493,6 +493,76 @@ pub fn symbol_name_for_instance_in_crate<'tcx>(
}
}

/// This is the symbol name of the given instance as seen by the linker.
///
/// On 32-bit Windows symbols are decorated according to their calling conventions.
pub fn linking_symbol_name_for_instance_in_crate<'tcx>(
tcx: TyCtxt<'tcx>,
symbol: ExportedSymbol<'tcx>,
instantiating_crate: CrateNum,
) -> String {
use rustc_target::abi::call::Conv;

let mut undecorated = symbol_name_for_instance_in_crate(tcx, symbol, instantiating_crate);

let target = &tcx.sess.target;
if !target.is_like_windows {
// Mach-O has a global "_" suffix and `object` crate will handle it.
// ELF does not have any symbol decorations.
return undecorated;
}

let x86 = match &target.arch[..] {
"x86" => true,
"x86_64" => false,
// Only x86/64 use symbol decorations.
_ => return undecorated,
};

let instance = match symbol {
ExportedSymbol::NonGeneric(def_id) | ExportedSymbol::Generic(def_id, _)
if tcx.is_static(def_id) =>
{
None
}
ExportedSymbol::NonGeneric(def_id) => Some(Instance::mono(tcx, def_id)),
ExportedSymbol::Generic(def_id, substs) => Some(Instance::new(def_id, substs)),
// DropGlue always use the Rust calling convention and thus follow the target's default
// symbol decoration scheme.
ExportedSymbol::DropGlue(..) => None,
// NoDefId always follow the target's default symbol decoration scheme.
ExportedSymbol::NoDefId(..) => None,
};

let (conv, args) = instance
.map(|i| {
tcx.fn_abi_of_instance(ty::ParamEnv::reveal_all().and((i, ty::List::empty())))
.unwrap_or_else(|_| bug!("fn_abi_of_instance({i:?}) failed"))
})
.map(|fnabi| (fnabi.conv, &fnabi.args[..]))
.unwrap_or((Conv::Rust, &[]));

// Decorate symbols with prefices, suffices and total number of bytes of arguments.
// Reference: https://docs.microsoft.com/en-us/cpp/build/reference/decorated-names?view=msvc-170
let (prefix, suffix) = match conv {
Conv::X86Fastcall => ("@", "@"),
Conv::X86Stdcall => ("_", "@"),
Conv::X86VectorCall => ("", "@@"),
_ => {
if x86 {
undecorated.insert(0, '_');
}
return undecorated;
}
};

let args_in_bytes: u64 = args
.iter()
.map(|abi| abi.layout.size.bytes().next_multiple_of(target.pointer_width as u64 / 8))
.sum();
format!("{prefix}{undecorated}{suffix}{args_in_bytes}")
}

fn wasm_import_module_map(tcx: TyCtxt<'_>, cnum: CrateNum) -> FxHashMap<DefId, String> {
// Build up a map from DefId to a `NativeLib` structure, where
// `NativeLib` internally contains information about
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_codegen_ssa/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
#![feature(nll)]
#![feature(associated_type_bounds)]
#![feature(strict_provenance)]
#![feature(int_roundings)]
#![recursion_limit = "256"]
#![allow(rustc::potential_query_instability)]

Expand Down
13 changes: 13 additions & 0 deletions src/test/ui/symbol-names/x86-stdcall.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,13 @@
// build-pass
// only-x86-windows
#![crate_type = "cdylib"]
#![feature(abi_vectorcall)]

#[no_mangle]
extern "stdcall" fn foo(_: bool) {}

#[no_mangle]
extern "fastcall" fn bar(_: u8) {}

#[no_mangle]
extern "vectorcall" fn baz(_: u16) {}

0 comments on commit 5560c51

Please sign in to comment.