From 751ecde0640f1d079515964e72e2646e82cb25f4 Mon Sep 17 00:00:00 2001
From: msizanoen <msizanoen@qtmlabs.xyz>
Date: Sun, 3 Sep 2023 15:58:21 +0700
Subject: [PATCH 1/2] rustc_target/riscv: Fix passing of transparent unions
with only one non-ZST member
This ensures that `MaybeUninit<T>` has the same ABI as `T` when passed
through an `extern "C"` function.
Fixes https://github.com/rust-lang/rust/issues/115481.
---
compiler/rustc_middle/src/ty/layout.rs | 4 ++++
compiler/rustc_target/src/abi/call/riscv.rs | 11 +++++++++++
compiler/rustc_target/src/abi/mod.rs | 8 ++++++++
3 files changed, 23 insertions(+)
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 9a0e72d7b64..8b425ce0267 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -1118,6 +1118,10 @@ where
fn is_unit(this: TyAndLayout<'tcx>) -> bool {
matches!(this.ty.kind(), ty::Tuple(list) if list.len() == 0)
}
+
+ fn is_transparent(this: TyAndLayout<'tcx>) -> bool {
+ matches!(this.ty.kind(), ty::Adt(def, _) if def.repr().transparent())
+ }
}
/// Calculates whether a function's ABI can unwind or not.
diff --git a/compiler/rustc_target/src/abi/call/riscv.rs b/compiler/rustc_target/src/abi/call/riscv.rs
index d90dce2a087..93a2045632a 100644
--- a/compiler/rustc_target/src/abi/call/riscv.rs
+++ b/compiler/rustc_target/src/abi/call/riscv.rs
@@ -89,6 +89,17 @@ where
}
FieldsShape::Union(_) => {
if !arg_layout.is_zst() {
+ if arg_layout.is_transparent() {
+ let non_1zst_elem = arg_layout.non_1zst_field(cx).expect("not exactly one non-1-ZST field in non-ZST repr(transparent) union").1;
+ return should_use_fp_conv_helper(
+ cx,
+ &non_1zst_elem,
+ xlen,
+ flen,
+ field1_kind,
+ field2_kind,
+ );
+ }
return Err(CannotUseFpConv);
}
}
diff --git a/compiler/rustc_target/src/abi/mod.rs b/compiler/rustc_target/src/abi/mod.rs
index 636adcf6b17..74fe98920c4 100644
--- a/compiler/rustc_target/src/abi/mod.rs
+++ b/compiler/rustc_target/src/abi/mod.rs
@@ -66,6 +66,7 @@ pub trait TyAbiInterface<'a, C>: Sized + std::fmt::Debug {
fn is_never(this: TyAndLayout<'a, Self>) -> bool;
fn is_tuple(this: TyAndLayout<'a, Self>) -> bool;
fn is_unit(this: TyAndLayout<'a, Self>) -> bool;
+ fn is_transparent(this: TyAndLayout<'a, Self>) -> bool;
}
impl<'a, Ty> TyAndLayout<'a, Ty> {
@@ -136,6 +137,13 @@ impl<'a, Ty> TyAndLayout<'a, Ty> {
Ty::is_unit(self)
}
+ pub fn is_transparent<C>(self) -> bool
+ where
+ Ty: TyAbiInterface<'a, C>,
+ {
+ Ty::is_transparent(self)
+ }
+
pub fn offset_of_subfield<C>(self, cx: &C, indices: impl Iterator<Item = usize>) -> Size
where
Ty: TyAbiInterface<'a, C>,
From 4d4c13bbd6584fea9972da5bbbecfa51285dbe68 Mon Sep 17 00:00:00 2001
From: msizanoen <msizanoen@qtmlabs.xyz>
Date: Tue, 19 Sep 2023 12:22:45 +0200
Subject: [PATCH 2/2] tests/ui/abi: Enable repr(transparent) union ABI tests on
RISC-V
---
tests/ui/abi/compatibility.rs | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/tests/ui/abi/compatibility.rs b/tests/ui/abi/compatibility.rs
index b3e75bb8233..d4f42cdda97 100644
--- a/tests/ui/abi/compatibility.rs
+++ b/tests/ui/abi/compatibility.rs
@@ -10,7 +10,6 @@ use std::ptr::NonNull;
// Hence there are `cfg` throughout this test to disable parts of it on those targets.
// sparc64: https://github.com/rust-lang/rust/issues/115336
// mips64: https://github.com/rust-lang/rust/issues/115404
-// riscv64: https://github.com/rust-lang/rust/issues/115481
// loongarch64: https://github.com/rust-lang/rust/issues/115509
macro_rules! assert_abi_compatible {
@@ -110,7 +109,7 @@ macro_rules! test_transparent {
test_abi_compatible!(wrap1, $t, Wrapper1<$t>);
test_abi_compatible!(wrap2, $t, Wrapper2<$t>);
test_abi_compatible!(wrap3, $t, Wrapper3<$t>);
- #[cfg(not(any(target_arch = "riscv64", target_arch = "loongarch64")))]
+ #[cfg(not(target_arch = "loongarch64"))]
test_abi_compatible!(wrap4, $t, WrapperUnion<$t>);
}
};