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Rollup merge of #142389 - beetrees:cranelift-arg-ext, r=bjorn3

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Apply ABI attributes on return types in `rustc_codegen_cranelift`

- The [x86-64 System V ABI standard](https://gitlab.com/x86-psABIs/x86-64-ABI/-/jobs/artifacts/master/raw/x86-64-ABI/abi.pdf?job=build) doesn't sign/zero-extend integer arguments or return types.
- But the de-facto standard as implemented by Clang and GCC is to sign/zero-extend arguments to 32 bits (but not return types).
- Additionally, Apple targets [sign/zero-extend both arguments and return values to 32 bits](https://developer.apple.com/documentation/xcode/writing-64-bit-intel-code-for-apple-platforms#Pass-arguments-to-functions-correctly).
- However, the `rustc_target` ABI adjustment code currently [unconditionally extends both arguments and return values to 32 bits](https://github.com/rust-lang/rust/blame/e703dff8fe220b78195c53478e83fb2f68d8499c/compiler/rustc_target/src/callconv/x86_64.rs#L240) on all targets.
- This doesn't cause a miscompilation when compiling with LLVM as LLVM will ignore the `signext`/`zeroext` attribute when applied to return types on non-Apple x86-64 targets.
- Cranelift, however, does not have a similar special case, requiring `rustc` to set the argument extension attribute correctly.
- However, `rustc_codegen_cranelift` doesn't currently apply ABI attributes to return types at all, meaning `rustc_codegen_cranelift` will currently miscompile `i8`/`u8`/`i16`/`u16` returns on x86-64 Apple targets as those targets require sign/zero-extension of return types.

This PR fixes the bug(s) by making the `rustc_target` x86-64 System V ABI only mark return types as sign/zero-extended on Apple platforms, while also making `rustc_codegen_cranelift` apply ABI attributes to return types. The RISC-V and s390x C ABIs also require sign/zero extension of return types, so this will fix those targets when building with `rustc_codegen_cranelift` too.

r? `````@bjorn3`````
This commit is contained in:
León Orell Valerian Liehr
2025-06-15 23:51:56 +02:00
committed by GitHub
parent 9795908dea 2457bb2cfb
commit 262e8210a5
1 changed files with 37 additions and 22 deletions
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src/abi/pass_mode.rs
+37 -22
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@@ -1,6 +1,6 @@
//! Argument passing
use cranelift_codegen::ir::{ArgumentExtension, ArgumentPurpose};
use cranelift_codegen::ir::ArgumentPurpose;
use rustc_abi::{Reg, RegKind};
use rustc_target::callconv::{
ArgAbi, ArgAttributes, ArgExtension as RustcArgExtension, CastTarget, PassMode,
@@ -32,13 +32,12 @@ fn reg_to_abi_param(reg: Reg) -> AbiParam {
AbiParam::new(clif_ty)
}
fn apply_arg_attrs_to_abi_param(mut param: AbiParam, arg_attrs: ArgAttributes) -> AbiParam {
fn apply_attrs_to_abi_param(param: AbiParam, arg_attrs: ArgAttributes) -> AbiParam {
match arg_attrs.arg_ext {
RustcArgExtension::None => {}
RustcArgExtension::Zext => param.extension = ArgumentExtension::Uext,
RustcArgExtension::Sext => param.extension = ArgumentExtension::Sext,
RustcArgExtension::None => param,
RustcArgExtension::Zext => param.uext(),
RustcArgExtension::Sext => param.sext(),
}
param
}
fn cast_target_to_abi_params(cast: &CastTarget) -> SmallVec<[AbiParam; 2]> {
@@ -82,7 +81,7 @@ impl<'tcx> ArgAbiExt<'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
match self.mode {
PassMode::Ignore => smallvec![],
PassMode::Direct(attrs) => match self.layout.backend_repr {
BackendRepr::Scalar(scalar) => smallvec![apply_arg_attrs_to_abi_param(
BackendRepr::Scalar(scalar) => smallvec![apply_attrs_to_abi_param(
AbiParam::new(scalar_to_clif_type(tcx, scalar)),
attrs
)],
@@ -97,8 +96,8 @@ impl<'tcx> ArgAbiExt<'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
let a = scalar_to_clif_type(tcx, a);
let b = scalar_to_clif_type(tcx, b);
smallvec![
apply_arg_attrs_to_abi_param(AbiParam::new(a), attrs_a),
apply_arg_attrs_to_abi_param(AbiParam::new(b), attrs_b),
apply_attrs_to_abi_param(AbiParam::new(a), attrs_a),
apply_attrs_to_abi_param(AbiParam::new(b), attrs_b),
]
}
_ => unreachable!("{:?}", self.layout.backend_repr),
@@ -112,19 +111,19 @@ impl<'tcx> ArgAbiExt<'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
// Abi requires aligning struct size to pointer size
let size = self.layout.size.align_to(tcx.data_layout.pointer_align.abi);
let size = u32::try_from(size.bytes()).unwrap();
smallvec![apply_arg_attrs_to_abi_param(
smallvec![apply_attrs_to_abi_param(
AbiParam::special(pointer_ty(tcx), ArgumentPurpose::StructArgument(size),),
attrs
)]
} else {
smallvec![apply_arg_attrs_to_abi_param(AbiParam::new(pointer_ty(tcx)), attrs)]
smallvec![apply_attrs_to_abi_param(AbiParam::new(pointer_ty(tcx)), attrs)]
}
}
PassMode::Indirect { attrs, meta_attrs: Some(meta_attrs), on_stack } => {
assert!(!on_stack);
smallvec![
apply_arg_attrs_to_abi_param(AbiParam::new(pointer_ty(tcx)), attrs),
apply_arg_attrs_to_abi_param(AbiParam::new(pointer_ty(tcx)), meta_attrs),
apply_attrs_to_abi_param(AbiParam::new(pointer_ty(tcx)), attrs),
apply_attrs_to_abi_param(AbiParam::new(pointer_ty(tcx)), meta_attrs),
]
}
}
@@ -133,30 +132,46 @@ impl<'tcx> ArgAbiExt<'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
fn get_abi_return(&self, tcx: TyCtxt<'tcx>) -> (Option<AbiParam>, Vec<AbiParam>) {
match self.mode {
PassMode::Ignore => (None, vec![]),
PassMode::Direct(_) => match self.layout.backend_repr {
BackendRepr::Scalar(scalar) => {
(None, vec![AbiParam::new(scalar_to_clif_type(tcx, scalar))])
}
PassMode::Direct(attrs) => match self.layout.backend_repr {
BackendRepr::Scalar(scalar) => (
None,
vec![apply_attrs_to_abi_param(
AbiParam::new(scalar_to_clif_type(tcx, scalar)),
attrs,
)],
),
BackendRepr::SimdVector { .. } => {
let vector_ty = crate::intrinsics::clif_vector_type(tcx, self.layout);
(None, vec![AbiParam::new(vector_ty)])
(None, vec![apply_attrs_to_abi_param(AbiParam::new(vector_ty), attrs)])
}
_ => unreachable!("{:?}", self.layout.backend_repr),
},
PassMode::Pair(_, _) => match self.layout.backend_repr {
PassMode::Pair(attrs_a, attrs_b) => match self.layout.backend_repr {
BackendRepr::ScalarPair(a, b) => {
let a = scalar_to_clif_type(tcx, a);
let b = scalar_to_clif_type(tcx, b);
(None, vec![AbiParam::new(a), AbiParam::new(b)])
(
None,
vec![
apply_attrs_to_abi_param(AbiParam::new(a), attrs_a),
apply_attrs_to_abi_param(AbiParam::new(b), attrs_b),
],
)
}
_ => unreachable!("{:?}", self.layout.backend_repr),
},
PassMode::Cast { ref cast, .. } => {
(None, cast_target_to_abi_params(cast).into_iter().collect())
}
PassMode::Indirect { attrs: _, meta_attrs: None, on_stack } => {
PassMode::Indirect { attrs, meta_attrs: None, on_stack } => {
assert!(!on_stack);
(Some(AbiParam::special(pointer_ty(tcx), ArgumentPurpose::StructReturn)), vec![])
(
Some(apply_attrs_to_abi_param(
AbiParam::special(pointer_ty(tcx), ArgumentPurpose::StructReturn),
attrs,
)),
vec![],
)
}
PassMode::Indirect { attrs: _, meta_attrs: Some(_), on_stack: _ } => {
unreachable!("unsized return value")