Fix the inline assembly examples

[strega-nil]

They now use the currently working syntax.

Also, I added two examples.

[rust-highfive]

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[strega-nil]

r? @steveklabnik

[steveklabnik]

@bors: r+ rollup

[bors]

📌 Commit a70b2ed has been approved by steveklabnik

[steveklabnik]

Thank you!

[bors]

⌛ Testing commit a70b2ed with merge c13dd9d...

[huonw]

I don't believe this is true, e.g. #24799 (comment) .

[strega-nil]

It is, I have tried it both ways.

[huonw]

Hm, well it's definitely not always required. E.g. to add to the example above, this also works (the not indicates that the correct register size is being used and it's not just, say, defaulting to eax in some way: the output is fffffffffffffffd):

#![feature(asm)]

fn main() {
    let mut test: u64;
    unsafe {
        asm!("mov $$2, %rax
              not %rax" 
             : "={ax}"(test));
    }
    println!("{:x}", test);
}

What's the other way in your example? (al -> ax?)

[huonw]

Oh, or maybe just {a}? It seems that {ax} always works (I see no difference in the asm between al and ax), but just a presumably means something different to LLVM.

[strega-nil]

That must be it. Just {a} doesn't work right now.

[bors]

💔 Test failed - auto-linux-64-nopt-t

[pnkfelix]

@bors r=steveklabnik 766c1bc

[bors]

⌛ Testing commit 766c1bc with merge 42bfeec...

[bors]

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-win-32-nopt-t, auto-win-32-opt, auto-win-64-nopt-t, auto-win-64-opt