Messages in this thread | | | Date | Sat, 13 Sep 2014 06:28:18 -0700 | From | Guenter Roeck <> | Subject | Re: [RFC][PATCH] signal: replace !likely with unlikely! |
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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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