02dfd63afe
Alice reported [1] that an arm64 build failed with:
ld.lld: error: undefined symbol: __extendsfdf2
>>> referenced by core.a6f5fc5794e7b7b3-cgu.0
>>> rust/core.o:(<f32>::midpoint) in archive vmlinux.a
>>> referenced by core.a6f5fc5794e7b7b3-cgu.0
>>> rust/core.o:(<f32>::midpoint) in archive vmlinux.a
ld.lld: error: undefined symbol: __truncdfsf2
>>> referenced by core.a6f5fc5794e7b7b3-cgu.0
>>> rust/core.o:(<f32>::midpoint) in archive vmlinux.a
Rust 1.80.0 or later together with `CONFIG_CC_OPTIMIZE_FOR_SIZE=y`
is what triggers it.
In addition, x86_64 builds also fail the same way.
Similarly, compiling with Rust 1.82.0 (currently in nightly) makes
another one appear, possibly due to the LLVM 19 upgrade there:
ld.lld: error: undefined symbol: __eqdf2
>>> referenced by core.20495ea57a9f069d-cgu.0
>>> rust/core.o:(<f64>::next_up) in archive vmlinux.a
>>> referenced by core.20495ea57a9f069d-cgu.0
>>> rust/core.o:(<f64>::next_down) in archive vmlinux.a
Gary adds [1]:
> Usually the fix on rustc side is to mark those functions as `#[inline]`
>
> All of {midpoint,next_up,next_down} are indeed unstable functions not
> marked as inline...
Fix all those by adding those intrinsics to our usual workaround.
[ Trevor quickly submitted a fix to upstream Rust [2] that has already
been merged, to be released in Rust 1.82.0 (2024-10-17). - Miguel ]
Cc: Gary Guo <gary@garyguo.net>
Reported-by: Alice Ryhl <aliceryhl@google.com>
Closes: https://rust-for-linux.zulipchat.com/#narrow/stream/x/topic/x/near/455637364 [1]
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Tested-by: Alice Ryhl <aliceryhl@google.com>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://github.com/rust-lang/rust/pull/128749 [2]
Link: https://lore.kernel.org/r/20240806150619.192882-1-ojeda@kernel.org
[ Shortened Zulip link. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
77 lines
2 KiB
Rust
77 lines
2 KiB
Rust
// SPDX-License-Identifier: GPL-2.0
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//! Our own `compiler_builtins`.
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//!
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//! Rust provides [`compiler_builtins`] as a port of LLVM's [`compiler-rt`].
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//! Since we do not need the vast majority of them, we avoid the dependency
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//! by providing this file.
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//!
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//! At the moment, some builtins are required that should not be. For instance,
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//! [`core`] has 128-bit integers functionality which we should not be compiling
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//! in. We will work with upstream [`core`] to provide feature flags to disable
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//! the parts we do not need. For the moment, we define them to [`panic!`] at
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//! runtime for simplicity to catch mistakes, instead of performing surgery
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//! on `core.o`.
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//!
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//! In any case, all these symbols are weakened to ensure we do not override
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//! those that may be provided by the rest of the kernel.
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//!
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//! [`compiler_builtins`]: https://github.com/rust-lang/compiler-builtins
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//! [`compiler-rt`]: https://compiler-rt.llvm.org/
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#![allow(internal_features)]
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#![feature(compiler_builtins)]
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#![compiler_builtins]
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#![no_builtins]
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#![no_std]
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macro_rules! define_panicking_intrinsics(
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($reason: tt, { $($ident: ident, )* }) => {
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$(
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#[doc(hidden)]
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#[export_name = concat!("__rust", stringify!($ident))]
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pub extern "C" fn $ident() {
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panic!($reason);
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}
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)*
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}
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);
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define_panicking_intrinsics!("`f32` should not be used", {
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__addsf3,
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__eqsf2,
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__extendsfdf2,
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__gesf2,
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__lesf2,
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__ltsf2,
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__mulsf3,
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__nesf2,
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__truncdfsf2,
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__unordsf2,
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});
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define_panicking_intrinsics!("`f64` should not be used", {
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__adddf3,
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__eqdf2,
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__ledf2,
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__ltdf2,
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__muldf3,
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__unorddf2,
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});
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define_panicking_intrinsics!("`i128` should not be used", {
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__ashrti3,
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__muloti4,
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__multi3,
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});
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define_panicking_intrinsics!("`u128` should not be used", {
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__ashlti3,
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__lshrti3,
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__udivmodti4,
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__udivti3,
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__umodti3,
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});
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// NOTE: if you are adding a new intrinsic here, you should also add it to
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// `redirect-intrinsics` in `rust/Makefile`.
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