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Rollup merge of #137094 - RalfJung:softfloat-means-no-simd, r=tgross35

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x86_win64 ABI: do not use xmm0 with softfloat ABI

This adjusts https://github.com/rust-lang/rust/pull/134290 to not apply the new logic to targets marked as "softfloat". That fixes most instances of the issue brought up [here](https://github.com/rust-lang/rust/issues/116558#issuecomment-2661027437).

r? `@tgross35`
This commit is contained in:
Matthias Krüger 2025-02-19 18:52:07 +01:00 • committed by GitHub
commit d8debbdd68
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3 changed files with 59 additions and 21 deletions
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16
compiler/rustc_target/src/callconv/x86_win64.rs
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@ -1,11 +1,11 @@
use rustc_abi::{BackendRepr, Float, Integer, Primitive, RegKind, Size};
use crate::callconv::{ArgAbi, FnAbi, Reg};
use crate::spec::HasTargetSpec;
use crate::spec::{HasTargetSpec, RustcAbi};
// 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>) {
pub(crate) fn compute_abi_info<Ty>(cx: &impl HasTargetSpec, fn_abi: &mut FnAbi<'_, Ty>) {
let fixup = |a: &mut ArgAbi<'_, Ty>, is_ret: bool| {
match a.layout.backend_repr {
BackendRepr::Uninhabited | BackendRepr::Memory { sized: false } => {}
@ -24,10 +24,14 @@ pub(crate) fn compute_abi_info<Ty>(_cx: &impl HasTargetSpec, fn_abi: &mut FnAbi<
}
BackendRepr::Scalar(scalar) => {
if is_ret && matches!(scalar.primitive(), Primitive::Int(Integer::I128, _)) {
// `i128` is returned in xmm0 by Clang and GCC
// FIXME(#134288): This may change for the `-msvc` targets in the future.
let reg = Reg { kind: RegKind::Vector, size: Size::from_bits(128) };
a.cast_to(reg);
if cx.target_spec().rustc_abi == Some(RustcAbi::X86Softfloat) {
// Use the native `i128` LLVM type for the softfloat ABI -- in other words, adjust nothing.
} else {
// `i128` is returned in xmm0 by Clang and GCC
// FIXME(#134288): This may change for the `-msvc` targets in the future.
let reg = Reg { kind: RegKind::Vector, size: Size::from_bits(128) };
a.cast_to(reg);
}
} else if a.layout.size.bytes() > 8
&& !matches!(scalar.primitive(), Primitive::Float(Float::F128))
{