exccause register missing (LLVM-59)

[MabezDev]

Trying to compile the following function with inline asm to read the exccause reg

#[no_mangle]
pub unsafe extern "C" fn _rust_user_exc() {
    let mut cause: u32;
    asm!("rsr.exccause a2" : "={a2}"(cause) );
}

leads to

error: <inline asm>:1:2: error: invalid register name
        rsr.exccause a2
        ^

  --> src/lib.rs:45:14

I ended up tracking down the register definitions, it seems like exccause is missing or has been split up for some reason

[igrr]

Indeed it is missing, it should be reg. 232: https://github.com/espressif/esp-idf/blob/f5b82c5b1f33f5287f9b5f1993594bf53755a4f2/components/xtensa/include/xtensa/specreg.h#L98