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|
//@ only-x86_64
//@ run-pass
//@ needs-asm-support
#![deny(unreachable_code)]
#![feature(asm_goto_with_outputs)]
use std::arch::asm;
fn goto_fallthough() {
unsafe {
asm!(
"/* {} */",
label {
unreachable!();
}
)
}
}
fn goto_jump() {
unsafe {
let mut value = false;
asm!(
"jmp {}",
label {
value = true;
}
);
assert!(value);
}
}
fn goto_out_fallthrough() {
unsafe {
let mut out: usize;
asm!(
"lea {}, [{} + 1]",
"/* {} */",
out(reg) out,
in(reg) 0x12345678usize,
label {
unreachable!();
}
);
assert_eq!(out, 0x12345679);
}
}
fn goto_out_jump() {
unsafe {
let mut value = false;
let mut out: usize;
asm!(
"lea {}, [{} + 1]",
"jmp {}",
out(reg) out,
in(reg) 0x12345678usize,
label {
value = true;
assert_eq!(out, 0x12345679);
}
);
assert!(value);
}
}
fn goto_out_jump_noreturn() {
unsafe {
let mut value = false;
let mut out: usize;
asm!(
"lea {}, [{} + 1]",
"jmp {}",
out(reg) out,
in(reg) 0x12345678usize,
label {
value = true;
assert_eq!(out, 0x12345679);
},
options(noreturn)
);
assert!(value);
}
}
// asm goto with outputs cause miscompilation in LLVM when multiple outputs are present.
// The code sample below is adapted from https://github.com/llvm/llvm-project/issues/74483
// and does not work with `-C opt-level=0`
#[expect(unused)]
fn goto_multi_out() {
#[inline(never)]
#[allow(unused)]
fn goto_multi_out(a: usize, b: usize) -> usize {
let mut x: usize;
let mut y: usize;
let mut z: usize;
unsafe {
core::arch::asm!(
"mov {x}, {a}",
"test {a}, {a}",
"jnz {label1}",
"/* {y} {z} {b} {label2} */",
x = out(reg) x,
y = out(reg) y,
z = out(reg) z,
a = in(reg) a,
b = in(reg) b,
label1 = label { return x },
label2 = label { return 1 },
);
0
}
}
assert_eq!(goto_multi_out(11, 22), 11);
}
fn goto_noreturn() {
unsafe {
let a;
asm!(
"jmp {}",
label {
a = 1;
},
options(noreturn)
);
assert_eq!(a, 1);
}
}
#[warn(unreachable_code)]
fn goto_noreturn_diverge() {
unsafe {
asm!(
"jmp {}",
label {
return;
},
options(noreturn)
);
unreachable!();
//~^ WARN unreachable statement
}
}
fn main() {
goto_fallthough();
goto_jump();
goto_out_fallthrough();
goto_out_jump();
goto_out_jump_noreturn();
// goto_multi_out();
goto_noreturn();
goto_noreturn_diverge();
}
|
