From 4f9acb268704a1c7f78c8c55da0d7614eac57ade Mon Sep 17 00:00:00 2001
From: Gary Guo <gary@garyguo.net>
Date: Tue, 26 Apr 2022 18:01:10 +0100
Subject: [PATCH 1/2] Use decorated names for linked_symbols on Windows
---
compiler/rustc_codegen_ssa/src/back/link.rs | 4 ++
compiler/rustc_codegen_ssa/src/back/linker.rs | 2 +-
.../src/back/symbol_export.rs | 72 ++++++++++++++++++-
compiler/rustc_codegen_ssa/src/lib.rs | 1 +
src/test/ui/symbol-names/x86-stdcall.rs | 13 ++++
5 files changed, 90 insertions(+), 2 deletions(-)
create mode 100644 src/test/ui/symbol-names/x86-stdcall.rs
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 743f6c0e5703d..54a69fcf68110 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -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() {
diff --git a/compiler/rustc_codegen_ssa/src/back/linker.rs b/compiler/rustc_codegen_ssa/src/back/linker.rs
index 6e13e0d0e43b1..0805df5dad6bf 100644
--- a/compiler/rustc_codegen_ssa/src/back/linker.rs
+++ b/compiler/rustc_codegen_ssa/src/back/linker.rs
@@ -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,
));
}
diff --git a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
index 3a416c8a2b54b..f651814be7ea6 100644
--- a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
+++ b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
@@ -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;
@@ -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
diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs
index d430800220930..05d32972dab17 100644
--- a/compiler/rustc_codegen_ssa/src/lib.rs
+++ b/compiler/rustc_codegen_ssa/src/lib.rs
@@ -7,6 +7,7 @@
#![feature(nll)]
#![feature(associated_type_bounds)]
#![feature(strict_provenance)]
+#![feature(int_roundings)]
#![recursion_limit = "256"]
#![allow(rustc::potential_query_instability)]
diff --git a/src/test/ui/symbol-names/x86-stdcall.rs b/src/test/ui/symbol-names/x86-stdcall.rs
new file mode 100644
index 0000000000000..9948488c0e950
--- /dev/null
+++ b/src/test/ui/symbol-names/x86-stdcall.rs
@@ -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) {}
From 0fce0db96f5d7f3b42d25412d3989014551852ac Mon Sep 17 00:00:00 2001
From: Gary Guo <gary@garyguo.net>
Date: Thu, 28 Apr 2022 16:22:40 +0100
Subject: [PATCH 2/2] Add `@feat.00` symbol to symbols.o for COFF
---
compiler/rustc_codegen_ssa/src/back/link.rs | 23 +++++++++++++++++++++
src/test/run-make/issue-96498/Makefile | 8 +++++++
src/test/run-make/issue-96498/foo.rs | 4 ++++
3 files changed, 35 insertions(+)
create mode 100644 src/test/run-make/issue-96498/Makefile
create mode 100644 src/test/run-make/issue-96498/foo.rs
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 54a69fcf68110..886ca9681e2b2 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -1700,6 +1700,29 @@ fn add_linked_symbol_object(
// 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);
+
+ // Add feature flags to the object file. On MSVC this is optional but LLD will complain if
+ // not present.
+ let mut feature = 0;
+
+ if file.architecture() == object::Architecture::I386 {
+ // Indicate that all SEH handlers are registered in .sxdata section.
+ // We don't have generate any code, so we don't need .sxdata section but LLD still
+ // expects us to set this bit (see #96498).
+ // Reference: https://docs.microsoft.com/en-us/windows/win32/debug/pe-format
+ feature |= 1;
+ }
+
+ file.add_symbol(object::write::Symbol {
+ name: "@feat.00".into(),
+ value: feature,
+ size: 0,
+ kind: object::SymbolKind::Data,
+ scope: object::SymbolScope::Compilation,
+ weak: false,
+ section: object::write::SymbolSection::Absolute,
+ flags: object::SymbolFlags::None,
+ });
}
for (sym, kind) in symbols.iter() {
diff --git a/src/test/run-make/issue-96498/Makefile b/src/test/run-make/issue-96498/Makefile
new file mode 100644
index 0000000000000..eae6400aee43a
--- /dev/null
+++ b/src/test/run-make/issue-96498/Makefile
@@ -0,0 +1,8 @@
+# only-windows
+# needs-rust-lld
+
+-include ../../run-make-fulldeps/tools.mk
+
+# Ensure that LLD can link
+all:
+ $(RUSTC) -C linker=rust-lld foo.rs
diff --git a/src/test/run-make/issue-96498/foo.rs b/src/test/run-make/issue-96498/foo.rs
new file mode 100644
index 0000000000000..93ac3641b098c
--- /dev/null
+++ b/src/test/run-make/issue-96498/foo.rs
@@ -0,0 +1,4 @@
+#![crate_type = "cdylib"]
+
+#[no_mangle]
+extern "C" fn foo() {}