Closed
Description
What does not work
I tried this code:
// lib.rs
static EIGHTEEN: usize = 18;
#[inline(always)]
pub fn add_to_18(x: usize) -> usize {
let mut y = x;
unsafe {
core::arch::asm!(
"add {y}, [rip + {eighteen}]",
y = inout(reg) y,
eighteen = sym EIGHTEEN,
);
}
y
}
// main.rs
fn main() {
println!("5 + 18 = {}", my_lib::add_to_18(5));
}
I expected to see this happen: output 5 + 18 = 23
Instead, this happened:
Compiling my_lib v0.1.0 (/home/user/my_lib)
error: linking with `clang` failed: exit status: 1
<...omitted...>
= note: mold: error: undefined symbol: my_lib::EIGHTEEN::he8c23468c01db196
>>> referenced by 1551ilekjbvb99xo
What works
#[no_mangle]
:
// lib.rs
#[no_mangle]
static EIGHTEEN: usize = 18;
#[inline(always)]
pub fn add_to_18(x: usize) -> usize {
let mut y = x;
unsafe {
core::arch::asm!(
"add {y}, [rip + {eighteen}]",
y = inout(reg) y,
eighteen = sym EIGHTEEN,
);
}
y
}
#[inline(never)]
:
// lib.rs
static EIGHTEEN: usize = 18;
#[inline(never)]
pub fn add_to_18(x: usize) -> usize {
let mut y = x;
unsafe {
core::arch::asm!(
"add {y}, [rip + {eighteen}]",
y = inout(reg) y,
eighteen = sym EIGHTEEN,
);
}
y
}
pub static
:
// lib.rs
pub static EIGHTEEN: usize = 18;
#[inline(always)]
pub fn add_to_18(x: usize) -> usize {
let mut y = x;
unsafe {
core::arch::asm!(
"add {y}, [rip + {eighteen}]",
y = inout(reg) y,
eighteen = sym EIGHTEEN,
);
}
y
}
Meta
rustc --version --verbose
:
rustc 1.67.0-nightly (a28f3c88e 2022-11-20)
binary: rustc
commit-hash: a28f3c88e50a77bc2a91889241248c4543854e61
commit-date: 2022-11-20
host: x86_64-unknown-linux-gnu
release: 1.67.0-nightly
LLVM version: 15.0.4
mold --version
:
mold 1.6.0 (323ad30e25c2c81efdb07ab76601a119335a40c8; compatible with GNU ld)
Also tried with ld
linker, got the same error.