Re: [Xen-devel] [PATCH] x86: fix variable_test_bit() asmconstraints

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 14/3/08 13:51, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

>> because at least I'm certain that works. Same for 'asm volatile'. We've had
>> various problems with the bitops before, and I just want the darn things to
>> work!
> 
> Okay, if you feel that way then I guess I won't propose changing it,
> at the expense of slightly worse code generation.

Frankly I'm scared to change it for the minuscule benefit we would derive
from it.

Regarding your other reply: I would actually be happy to change the bitops
to work with longs only. I suspect, and would need to have demonstrated
otherwise, that supporting bitops on arbitrary-width fields down to the
instruction level is not really worthwhile. Either way, I accept that what
we do now is dubious at best.

 -- Keir



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