Re: [PATCH v3 1/4] dbghelp: Avoid using inline assembly in do_x86cpuid().

[Zebediah Figura]

On 11/26/2018 12:35 PM, Gabriel Ivăncescu wrote:
> Just out of curiosity, what is wrong with the inline assembly here
> (and the other patches)? To me it looks easier to maintain and
> generates better code.
>
> I know there's a reason, that's why I'm asking :-)

"Easier to maintain" may be subjective; I personally find the constraint 
mnemonics harder to read. In any case I doubt that performance should be 
a concern here.

The first such patch I sent was 0c216b8ca, it was motivated by clang 
generating references to %esp despite the use of stack instructions (and 
despite -fno-omit-frame-pointer). Alexandre prescribed avoiding inline 
assembly for all but the most simple functions, IIRC because constraints 
are generally trickier to get right.