Crash on asm!("int $3"): Wrong MachineOperand accessor

[kryptan]

While compiling the following program:

#![feature(asm)]

fn main() {
    unsafe {
        asm!("int $3");
    } 
}

rustc crashes:

D:\rust>rustc crash.rs
Assertion failed!

Program: C:\Program Files\Rust-nightly\bin\rustc.exe
File: C:/bot/slave/nightly-dist-rustc-win-64/build/src/llvm/include/llvm/CodeGen/MachineOperand.h, Line 408

Expression: isImm() && "Wrong MachineOperand accessor"

This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.

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D:\rust>rustc --version --verbose
rustc 1.0.0-nightly (30e1f9a1c 2015-03-14) (built 2015-03-15)
binary: rustc
commit-hash: 30e1f9a1c2bf7134135800bc9afd082773defadc
commit-date: 2015-03-14
build-date: 2015-03-15
host: x86_64-pc-windows-gnu
release: 1.0.0-nightly

[achanda]

Could not repro this on OSX

Abhishek@Abhisheks-MacBook-Pro:~/src/rust (master %=)$ ./x86_64-apple-darwin/stage2/bin/rustc crash.rs
crash.rs:5:9: 5:24 error: <inline asm>:1:2: error: too few operands for instruction
        int
        ^

crash.rs:5         asm!("int $3");
                   ^~~~~~~~~~~~~~~
error: aborting due to previous error
Abhishek@Abhisheks-MacBook-Pro:~/src/rust (master %=)$ ./x86_64-apple-darwin/stage2/bin/rustc --version --verbose
rustc 1.0.0-dev (c897ac04e 2015-04-10) (built 2015-04-10)
binary: rustc
commit-hash: c897ac04e2ebda378fd9e38f6ec0878ae3a2baf7
commit-date: 2015-04-10
build-date: 2015-04-10
host: x86_64-apple-darwin
release: 1.0.0-dev
Abhishek@Abhisheks-MacBook-Pro:~/src/rust (master %=)$ cat crash.rs
#![feature(asm)]

fn main() {
    unsafe {
        asm!("int $3");
    }
}

[steveklabnik]

This still reproduces for me today on Linux.

[Ekleog]

Just had the same issue. For the record, using asm!(".byte 0xCC"); is a workaround on x86_64, when using the intrinsics is not a possibility (like when in a #[naked] function).

[Ekleog]

For the record (bis), asm!("int3") is a cleaner workaround.

[jcranmer]

FWIW, LLVM's inline ASM uses $ as the sigil for substitution, not % as in Clang and GCC.

Using asm!("int $$3"); works.

[cyplo]

Still ICEs, different message;

Using asm!("int $$3"); makes the program compile with rustc 1.33.0-nightly (2d3e909e4 2018-12-22) while the original code with asm!("int $3"); still ICEs, the message is different now though:

thread '<unnamed>' panicked at 'called `Option::unwrap()` on a `None` value', src/libcore/option.rs:355:21                                                                                   
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
[1]    13385 illegal hardware instruction (core dumped)  rustc test.rs