ice: None, asm

[matthiaskrgr]

auto-reduced (treereduce-rust):

#![crate_type = "rlib"]

use std::arch::asm;
use std::mem::MaybeUninit;

pub unsafe fn inout(mut x: i32) -> MaybeUninit<i32> {
    let y: MaybeUninit<i32>;
    asm!("/*{}{}*/", in(reg) x, out(reg) y);
    y
}

original:

// compile-flags: -O
// only-x86_64

#![crate_type = "rlib"]
#![allow(asm_sub_register)]

use std::mem::MaybeUninit;
use std::arch::asm;

// CHECK-LABEL: @int
#[no_mangle]
pub unsafe fn int(x: MaybeUninit<i32>) -> MaybeUninit<i32> {
    let y: MaybeUninit<i32>;
    asm!("/*{}{}*/", in(reg) x, out(reg) y);
    y
}

// CHECK-LABEL: @inout
#[no_mangle]
pub unsafe fn inout(mut x: i32) -> MaybeUninit<i32> {
    let y: MaybeUninit<i32>;
    asm!("/*{}{}*/", in(reg) x, out(reg) y);
    y
}

Version information

rustc 1.76.0-nightly (e24e5af78 2023-11-21)
binary: rustc
commit-hash: e24e5af787f7015914cbf316063ed5821f370b71
commit-date: 2023-11-21
host: x86_64-unknown-linux-gnu
release: 1.76.0-nightly
LLVM version: 17.0.5

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc -Zcodegen-backend=cranelift

Program output

warning: formatting may not be suitable for sub-register argument
 --> /tmp/icemaker_global_tempdir.Tt4eJle1ugDg/rustc_testrunner_tmpdir_reporting.vPTLPZ3IgX7I/mvce.rs:8:13
  |
8 |     asm!("/*{}{}*/", in(reg) x, out(reg) y);
  |             ^^               - for this argument
  |
  = help: use `{0:e}` to have the register formatted as `eax`
  = help: or use `{0:r}` to keep the default formatting of `rax`
  = note: `#[warn(asm_sub_register)]` on by default

warning: formatting may not be suitable for sub-register argument
 --> /tmp/icemaker_global_tempdir.Tt4eJle1ugDg/rustc_testrunner_tmpdir_reporting.vPTLPZ3IgX7I/mvce.rs:8:15
  |
8 |     asm!("/*{}{}*/", in(reg) x, out(reg) y);
  |               ^^                         - for this argument
  |
  = help: use `{1:e}` to have the register formatted as `eax`
  = help: or use `{1:r}` to keep the default formatting of `rax`

warning: variable does not need to be mutable
 --> /tmp/icemaker_global_tempdir.Tt4eJle1ugDg/rustc_testrunner_tmpdir_reporting.vPTLPZ3IgX7I/mvce.rs:6:21
  |
6 | pub unsafe fn inout(mut x: i32) -> MaybeUninit<i32> {
  |                     ----^
  |                     |
  |                     help: remove this `mut`
  |
  = note: `#[warn(unused_mut)]` on by default

thread 'rustc' panicked at src/inline_asm.rs:764:45:
called `Option::unwrap()` on a `None` value
stack backtrace:
   0:     0x7f0ae758aafc - std::backtrace_rs::backtrace::libunwind::trace::h0b040baf97a1a814
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
   1:     0x7f0ae758aafc - std::backtrace_rs::backtrace::trace_unsynchronized::h3bb4f35c883ef0b7
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f0ae758aafc - std::sys_common::backtrace::_print_fmt::h7bc4c6c40e2dea38
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7f0ae758aafc - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::ha29c192b6f9a05c7
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f0ae75ddc80 - core::fmt::rt::Argument::fmt::hd5d7e2c681722c4a
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/core/src/fmt/rt.rs:142:9
   5:     0x7f0ae75ddc80 - core::fmt::write::h44f28bd6729c28a7
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/core/src/fmt/mod.rs:1120:17
   6:     0x7f0ae757e91f - std::io::Write::write_fmt::h34e80b21f77f27fe
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/std/src/io/mod.rs:1762:15
   7:     0x7f0ae758a8e4 - std::sys_common::backtrace::_print::hf6fce87ec4803f0c
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f0ae758a8e4 - std::sys_common::backtrace::print::h2c7cd590dc94a621
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f0ae758d577 - std::panicking::default_hook::{{closure}}::ha2265235df34f52e
  10:     0x7f0ae758d2df - std::panicking::default_hook::ha134722f286c6b3a
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/std/src/panicking.rs:292:9
  11:     0x7f0aea2f42b0 - std[9e66bc0d43e7428]::panicking::update_hook::<alloc[6053f7fa92048905]::boxed::Box<rustc_driver_impl[6d46853ed3c470a0]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7f0ae758dcb8 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h3506115e7630eb0e
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/alloc/src/boxed.rs:2021:9
  13:     0x7f0ae758dcb8 - std::panicking::rust_panic_with_hook::h7694bf37e5dc3efe
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/std/src/panicking.rs:783:13
  14:     0x7f0ae758d9d9 - std::panicking::begin_panic_handler::{{closure}}::h2dd4c764b0c8af53
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/std/src/panicking.rs:649:13
  15:     0x7f0ae758afc6 - std::sys_common::backtrace::__rust_end_short_backtrace::h7c23b4f1d73ba22d
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/std/src/sys_common/backtrace.rs:171:18
  16:     0x7f0ae758d772 - rust_begin_unwind
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/std/src/panicking.rs:645:5
  17:     0x7f0ae75da365 - core::panicking::panic_fmt::hc4f69c74680b17c4
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/core/src/panicking.rs:72:14
  18:     0x7f0ae75da403 - core::panicking::panic::hafadf320ec949d41
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/core/src/panicking.rs:127:5
  19:     0x7f0addc2b6cf - rustc_codegen_cranelift[5ecdc7bd26b881e3]::inline_asm::codegen_inline_asm_inner
  20:     0x7f0addc031fd - rustc_codegen_cranelift[5ecdc7bd26b881e3]::base::codegen_fn_body
  21:     0x7f0addc17934 - rustc_codegen_cranelift[5ecdc7bd26b881e3]::driver::aot::module_codegen::{closure#0}
  22:     0x7f0addc14c45 - rustc_codegen_cranelift[5ecdc7bd26b881e3]::driver::aot::module_codegen
  23:     0x7f0addc2124c - rustc_codegen_cranelift[5ecdc7bd26b881e3]::driver::aot::run_aot
  24:     0x7f0addc4d59a - <rustc_codegen_cranelift[5ecdc7bd26b881e3]::CraneliftCodegenBackend as rustc_codegen_ssa[701c7bd28a7a1232]::traits::backend::CodegenBackend>::codegen_crate
  25:     0x7f0aebf669d7 - rustc_interface[79d196cce7f623b3]::passes::start_codegen
  26:     0x7f0aebf66399 - <rustc_interface[79d196cce7f623b3]::queries::Queries>::ongoing_codegen
  27:     0x7f0aec6136c7 - rustc_interface[79d196cce7f623b3]::interface::run_compiler::<core[4409ec5cd92597ed]::result::Result<(), rustc_span[433598ff900853dd]::ErrorGuaranteed>, rustc_driver_impl[6d46853ed3c470a0]::run_compiler::{closure#0}>::{closure#0}
  28:     0x7f0aec5a3054 - std[9e66bc0d43e7428]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[79d196cce7f623b3]::util::run_in_thread_with_globals<rustc_interface[79d196cce7f623b3]::util::run_in_thread_pool_with_globals<rustc_interface[79d196cce7f623b3]::interface::run_compiler<core[4409ec5cd92597ed]::result::Result<(), rustc_span[433598ff900853dd]::ErrorGuaranteed>, rustc_driver_impl[6d46853ed3c470a0]::run_compiler::{closure#0}>::{closure#0}, core[4409ec5cd92597ed]::result::Result<(), rustc_span[433598ff900853dd]::ErrorGuaranteed>>::{closure#0}, core[4409ec5cd92597ed]::result::Result<(), rustc_span[433598ff900853dd]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[4409ec5cd92597ed]::result::Result<(), rustc_span[433598ff900853dd]::ErrorGuaranteed>>
  29:     0x7f0aec5a2e7d - <<std[9e66bc0d43e7428]::thread::Builder>::spawn_unchecked_<rustc_interface[79d196cce7f623b3]::util::run_in_thread_with_globals<rustc_interface[79d196cce7f623b3]::util::run_in_thread_pool_with_globals<rustc_interface[79d196cce7f623b3]::interface::run_compiler<core[4409ec5cd92597ed]::result::Result<(), rustc_span[433598ff900853dd]::ErrorGuaranteed>, rustc_driver_impl[6d46853ed3c470a0]::run_compiler::{closure#0}>::{closure#0}, core[4409ec5cd92597ed]::result::Result<(), rustc_span[433598ff900853dd]::ErrorGuaranteed>>::{closure#0}, core[4409ec5cd92597ed]::result::Result<(), rustc_span[433598ff900853dd]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[4409ec5cd92597ed]::result::Result<(), rustc_span[433598ff900853dd]::ErrorGuaranteed>>::{closure#1} as core[4409ec5cd92597ed]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  30:     0x7f0ae7597b75 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::he2fe898dabd7bf63
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/alloc/src/boxed.rs:2007:9
  31:     0x7f0ae7597b75 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h2e31e36ca472739b
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/alloc/src/boxed.rs:2007:9
  32:     0x7f0ae7597b75 - std::sys::unix::thread::Thread::new::thread_start::h72b7daa856b881db
                               at /rustc/e24e5af787f7015914cbf316063ed5821f370b71/library/std/src/sys/unix/thread.rs:108:17
  33:     0x7f0ae73889eb - <unknown>
  34:     0x7f0ae740c7cc - <unknown>
  35:                0x0 - <unknown>

error: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.76.0-nightly (e24e5af78 2023-11-21) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z codegen-backend=cranelift -Z dump-mir-dir=dir

query stack during panic:
end of query stack
warning: 3 warnings emitted

[bjorn3]

I didn't know MaybeUninit was allowed as asm operand.