bjoernager/rust
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on Windows, consistently pass ZST by-ref

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This commit is contained in:
Ralf Jung 2025-01-08 15:32:09 +01:00
parent d760bb6603
commit 675a1036ca
4 changed files with 22 additions and 57 deletions
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4
compiler/rustc_target/src/callconv/mod.rs
View file

@ -665,11 +665,11 @@ impl<'a, Ty> FnAbi<'a, Ty> {
"x86_64" => match abi {
ExternAbi::SysV64 { .. } => x86_64::compute_abi_info(cx, self),
ExternAbi::Win64 { .. } | ExternAbi::Vectorcall { .. } => {
x86_win64::compute_abi_info(cx, self, abi)
x86_win64::compute_abi_info(cx, self)
}
_ => {
if cx.target_spec().is_like_windows {
x86_win64::compute_abi_info(cx, self, abi)
x86_win64::compute_abi_info(cx, self)
} else {
x86_64::compute_abi_info(cx, self)
}

22
compiler/rustc_target/src/callconv/x86_win64.rs
View file

@ -1,15 +1,11 @@
use rustc_abi::{BackendRepr, ExternAbi, Float, Primitive};
use rustc_abi::{BackendRepr, Float, Primitive};
use crate::abi::call::{ArgAbi, FnAbi, Reg};
use crate::spec::HasTargetSpec;
// Win64 ABI: https://docs.microsoft.com/en-us/cpp/build/parameter-passing
pub(crate) fn compute_abi_info<Ty>(
cx: &impl HasTargetSpec,
fn_abi: &mut FnAbi<'_, Ty>,
abi: ExternAbi,
) {
pub(crate) fn compute_abi_info<Ty>(_cx: &impl HasTargetSpec, fn_abi: &mut FnAbi<'_, Ty>) {
let fixup = |a: &mut ArgAbi<'_, Ty>| {
match a.layout.backend_repr {
BackendRepr::Uninhabited | BackendRepr::Memory { sized: false } => {}
@ -48,16 +44,14 @@ pub(crate) fn compute_abi_info<Ty>(
// Windows ABIs do not talk about ZST since such types do not exist in MSVC.
// In that sense we can do whatever we want here, and maybe we should throw an error
// (but of course that would be a massive breaking change now).
// We try to match clang and gcc, so we make windows-gnu and the native
// Windows ABIs (i.e., everything except for `extern "C"`) pass ZST via
// pointer indirection. windows-msvc `extern "C"` still skips ZST.
if (cx.target_spec().os == "windows" && cx.target_spec().env == "gnu")
|| !matches!(abi, ExternAbi::C { .. })
{
arg.make_indirect_from_ignore();
}
// We try to match clang and gcc (which allow ZST is their windows-gnu targets), so we
// pass ZST via pointer indirection.
arg.make_indirect_from_ignore();
continue;
}
fixup(arg);
}
// FIXME: We should likely also do something about ZST return types, similar to above.
// However, that's non-trivial due to `()`.
// See <https://github.com/rust-lang/unsafe-code-guidelines/issues/552>.
}

39
compiler/rustc_ty_utils/src/abi.rs
View file

@ -267,10 +267,8 @@ fn fn_sig_for_fn_abi<'tcx>(
#[inline]
fn conv_from_spec_abi(tcx: TyCtxt<'_>, abi: ExternAbi, c_variadic: bool) -> Conv {
let target = &tcx.sess.target;
use rustc_abi::ExternAbi::*;
match target.adjust_abi(abi, c_variadic) {
match tcx.sess.target.adjust_abi(abi, c_variadic) {
RustIntrinsic | Rust | RustCall => Conv::Rust,
// This is intentionally not using `Conv::Cold`, as that has to preserve
@ -281,37 +279,10 @@ fn conv_from_spec_abi(tcx: TyCtxt<'_>, abi: ExternAbi, c_variadic: bool) -> Conv
System { .. } => bug!("system abi should be selected elsewhere"),
EfiApi => bug!("eficall abi should be selected elsewhere"),
// See commentary in `is_abi_supported`: we map these to "C" on targets
// where they do not make sense.
Stdcall { .. } => {
if target.arch == "x86" {
Conv::X86Stdcall
} else {
Conv::C
}
}
Fastcall { .. } => {
if target.arch == "x86" {
Conv::X86Fastcall
} else {
Conv::C
}
}
Vectorcall { .. } => {
if ["x86", "x86_64"].contains(&&target.arch[..]) {
Conv::X86VectorCall
} else {
Conv::C
}
}
Thiscall { .. } => {
if target.arch == "x86" {
Conv::X86ThisCall
} else {
Conv::C
}
}
Stdcall { .. } => Conv::X86Stdcall,
Fastcall { .. } => Conv::X86Fastcall,
Vectorcall { .. } => Conv::X86VectorCall,
Thiscall { .. } => Conv::X86ThisCall,
C { .. } => Conv::C,
Unadjusted => Conv::C,
Win64 { .. } => Conv::X86_64Win64,

14
tests/codegen/abi-win64-zst.rs
View file

@ -23,16 +23,16 @@ trait Sized {}
// Make sure the argument is always passed when explicitly requesting a Windows ABI.
// Our goal here is to match clang: <https://clang.godbolt.org/z/Wr4jMWq3P>.
// CHECK: define win64cc void @pass_zst_win64(ptr {{.*}})
// CHECK: define win64cc void @pass_zst_win64(ptr {{[^,]*}})
#[no_mangle]
extern "win64" fn pass_zst_win64(_: ()) {}
// CHECK: define x86_vectorcallcc void @pass_zst_vectorcall(ptr {{.*}})
// CHECK: define x86_vectorcallcc void @pass_zst_vectorcall(ptr {{[^,]*}})
#[no_mangle]
extern "vectorcall" fn pass_zst_vectorcall(_: ()) {}
// windows-gnu: define void @pass_zst_fastcall(ptr {{.*}})
// windows-msvc: define void @pass_zst_fastcall(ptr {{.*}})
// windows-gnu: define void @pass_zst_fastcall(ptr {{[^,]*}})
// windows-msvc: define void @pass_zst_fastcall(ptr {{[^,]*}})
#[no_mangle]
#[cfg(windows)] // "fastcall" is not valid on 64bit Linux
extern "fastcall" fn pass_zst_fastcall(_: ()) {}
@ -43,10 +43,10 @@ extern "fastcall" fn pass_zst_fastcall(_: ()) {}
#[no_mangle]
extern "sysv64" fn pass_zst_sysv64(_: ()) {}
// For `extern "C"` functions, ZST are ignored on windows-msvc.
// For `extern "C"` functions, ZST are ignored on Linux put passed on Windows.
// linux: define void @pass_zst_c()
// windows-msvc: define void @pass_zst_c()
// windows-gnu: define void @pass_zst_c(ptr {{.*}})
// windows-msvc: define void @pass_zst_c(ptr {{[^,]*}})
// windows-gnu: define void @pass_zst_c(ptr {{[^,]*}})
#[no_mangle]
extern "C" fn pass_zst_c(_: ()) {}