Re: pud_bad vs pud_bad

[Ingo Molnar]

* Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:

> Ingo Molnar wrote:
>> But the 32-bit check does the exact same thing but via a single binary  
>> operation: it checks whether any bits outside of those bits are zero - 
>> just via a simpler test that compiles to more compact code.
>>
>> So i'd go with the 32-bit version. (unless there are some 
>> sign-extension complications i'm missing - but i think we got rid of 
>> those already.)
>
> OK, fair enough.  I wouldn't be surprised if gcc does that transform 
> anyway, but we may as well be consistent about it.

i checked and it doesnt - at least 4.3.2 inserts an extra AND instruction. 
So the 32-bit version is really better. (beyond being more readable)

	Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/