Resolve #51, use new asm! macro

[maelgui]

Resolve issue #51

We replaced all the llvm_asm! call with the new asm! macro, which implies:

• Use intel syntax by default (coherent with asm code used in the project)
• We tried to choose the best option (nomem, nostack, etc...) for each call
• "m" memory operand does not exist anymore, which implies passing reference address through a register

We tried to ensure the generated assembly stayed the same, using rust playground.

[ALSchwalm]

Awesome! I'll take a look at this tomorrow. Before merger though, I'd like some of these commits squashed, e.g.
92d1672 looks like a fix for an earlier commit, and f385de6 has the same commit message as c9e846f. But at a glance this looks really solid.

[maelgui]

I rewrote the history, and squashed the two or three commits that were the same.

[ALSchwalm]

Ok, reading through these changes it looks good to me. I had one concern, which is that in a few places we no longer express that the rflags register is clobbered by the asm. However, it appears that is not possible to specify, as it is implied unless preserves_flags is set (per rust-lang/project-inline-asm#5). Does that align with your understanding of things? I'm not that familiar with the new asm stuff (but it certainly seems nicer to use than llvm_asm).

Thanks again for working on this.

[ALSchwalm]

I'm going to go ahead and merge this. Thanks for the contribution!

[paulcacheux]

Thanks for merging it. What you figured about preserves_flags matches our understanding of the new macro. It seems that the new options of the asm! macro are defined as opposites of the old llvm_asm ones such as no options is nearly always at least correct and then you can optimize by providing more information (like nomem, nostack, pure, preserves_flags, etc).