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
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@ -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>.
}