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Re: Builtin expansion versus headers optimization: Reductions


OndÅej BÃlka <neleai@seznam.cz> writes:
>
> On ivy bridge I got that Using rep stosq for memset(x,0,4096) is 20%
> slower than libcall for L1 cache resident data while 50% faster for data
> outside cache. How do you teach compiler that?

It would be in theory possible with autofdo. Profile with a cache miss
event. Correlate. Maintain the information in addition to the basic
block frequencies.

Probably not simple, but definitely possible.

-Andi
-- 
ak@linux.intel.com -- Speaking for myself only


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