Hi Martin, On 1/11/19 5:22 PM, Martin Liška wrote: > On 1/11/19 4:03 AM, Cao jin wrote: >> Now the questions is: from code-reading, it is kind of non-intuitive, is >> there any explicit way to control the optimization behavior accurately? > > Hi. > > Please take a look here: > https://gcc.gnu.org/onlinedocs/gcc.pdf Yes, I already have it and spent some time on it. It just a little bit difficult for GCC newbie to find the answer accurately(I searched some of the used flags). > > you are searching for: > -mmemcpy > -mno-memcpy > Force (do not force) the use of memcpy for non-trivial block moves. The default > is ‘-mno-memcpy’, which allows GCC to inline most constant-sized copies I tried -mmemcpy, it seems these two are not for x86. > > and possibly for: > -mmemcpy-strategy > > and > -mstringop-strategy=alg > And yes, -mmemcpy-strategy worked as I expected. Thanks very much! -- Sincerely, Cao jin
