Re: [RFC][PATCH] signal: replace !likely with unlikely!

[Guenter Roeck]

On 09/13/2014 03:04 AM, Richard Weinberger wrote:
> Am 13.09.2014 04:48, schrieb Li RongQing:
> > I did not test, how to test it?
>
> Compare the object files of both variants to find out whether both create
> semantically equivalent code and whether the un/likely have an effect.
> i.e. objdump -S -d kernel/signal.o
> I guess you can just remove the likely as gcc is smart enough to detect the "goto ret;"
> as an unlikely taken branch.
Or just write similar test code and observe the result.

When you are doing that, you might learn that if "(!likely(expression))"
is _not_ the same as "if (unlikely(!expression))".

Guenter

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