[Mesa-dev] [PATCH excerpt] mesa: Wrap unlikely() around conditions leading to _mesa_error().

[Brian Paul]

On 03/02/2015 04:03 PM, Eric Anholt wrote:
> Kenneth Graunke <kenneth at whitecape.org> writes:
>
>> Generated by the following Coccinelle semantic patch:
>>
>> @@
>> expression E;
>> @@
>> if (
>> -E
>> +unlikely(E)
>>   )
>> { ... _mesa_error(...) ... }
>>
>> Improves performance in OglBatch7 (a CPU-bound microbenchmark) on
>> an i7 4750HQ (Haswell) by 1.08546% +/- 0.519734% (n=292).
>>
>> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
>
> Neat!
>
> I think you're supposed to be able to get the same result by marking
> _mesa_error as attribute cold.  Then nobody can forget to mark their
> conditions as unlikely in the future.

I suspect unlikely() would be supported by more compilers than 'cold'.

-Brian