compiler abort in LLVM code when using a newtype-wrapper as an argument

[TethysSvensson]

The following program will cause an abort in llvm/lib/IR/InlineAsm.cpp:

#![feature(asm)]

pub struct Wrapper(uint);

fn main() {
    let mut value: Wrapper = Wrapper(7);
    unsafe {
        asm!("mov %eax, $0" : "+r"(value));
    }
}

The error message I get is:

rustc: /build/buildd/rust-nightly-201407030406~67776ba~utopic/src/llvm/lib/IR/InlineAsm.cpp:47: llvm::InlineAsm::InlineAsm(llvm::PointerType*, const string&, const string&, bool, bool, llvm::InlineAsm::AsmDialect): Assertion `Verify(getFunctionType(), constraints) && "Function type not legal for constraints!"' failed.
Aborted (core dumped)

I am using the rust nightly build version 20140703040667776bautopic.

[richo]

Just ran into this again, however for a lot of this year this worked, as I wrote some code that does this.

[tamird]

This once again does not ICE:

#![feature(asm)]

pub struct Wrapper(u32);

fn main() {
    let mut value: Wrapper = Wrapper(7);
    unsafe {
        asm!("mov %eax, $0" : "+r"(value));
    }
}

@steveklabnik E-needstest?

[jooert]

With LLVM assertions enabled, this still fails with the same error message.

[jethrogb]

The error depends on the exact asm invocation.

#![feature(asm)]

#[repr(packed)]
struct Bitfield<T>(T);

fn test()->(Bitfield<u32>,Bitfield<u32>) {
    let mut out=(Bitfield(0),Bitfield(0));
    unsafe{asm!("" : "={eax}"(out.0), "={ebx}"(out.1))};
    out
}

fn main() {
    test();
}

yields:

Unknown type!
UNREACHABLE executed at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/src/llvm/lib/IR/ValueTypes.cpp:253!

While this

#![feature(asm)]

#[repr(packed)]
struct Bitfield<T>(T);

fn test()->(Bitfield<u32>,Bitfield<u32>) {
    let mut out=(Bitfield(0),Bitfield(0));
    unsafe{asm!("" : "={eax}"(out.0))};
    out
}

fn main() {
    test();
}

yields:

rustc: /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/src/llvm/lib/IR/InlineAsm.cpp:47: llvm::InlineAsm::InlineAsm(llvm::PointerType*, const string&, const string&, bool, bool, llvm::InlineAsm::AsmDialect): Assertion `Verify(getFunctionType(), constraints) && "Function type not legal for constraints!"' failed.

[chordowl]

Triage: still reproduces

rustc: /checkout/src/llvm/lib/IR/InlineAsm.cpp:46: llvm::InlineAsm::InlineAsm(llvm::FunctionType*, const string&, const string&, bool, bool, llvm::InlineAsm::AsmDialect): Assertion `Verify(getFunctionType(), constraints) && "Function type not legal for constraints!"' failed.
error: Could not compile `playground`.

[steveklabnik]

This no longer ICEs!

[petrochenkov]

Because LLVM assertions were disabled on nightly #45810

[pnkfelix]

ICE is dependent on feature(asm) (cc #29722), which is not on the 2019 roadmap. Marking as P-medium until we get an overall plan for asm in Rust. (Although the fact that this can cause rustc itself to segfault, presumably via a problem internal to LLVM, does lead me to wonder if I should up the priority to P-high anyway.)

[Amanieu]

This issue does not apply to the new asm! (RFC 2850) which has stricter checks on the types that can be used as asm operands.

The legacy llvm_asm! is deprecated and is no longer maintained.