I guess some optimizations are controlled only by "optimize_size", not by the profile. Other optimizations are controlled by the profile. So this patch does not have very much effectiveness (only 0.9% size reduction).
2014-07-23 17:26 GMT+08:00 Richard Biener <richard.guent...@gmail.com>: > On Wed, Jul 23, 2014 at 2:39 AM, Pengfei Yuan <0xcool...@gmail.com> wrote: >> In the experiment, about 60% (1019/1699) profile data files are empty >> (all counters are zero). > > Well, but you are globally overriding options even for the parts with > profile. The whole point of profile-feedback is to get at the interesting > parts (those with non-zero counters). > > What you say is that not enough parts of the compiler care for > the actual profiles and thus portions with all-zero counters are > treated as if they were hot? Then better fix that. > > Richard. > >> 2014-07-22 21:39 GMT+08:00 Richard Biener <richard.guent...@gmail.com>: >>> On Mon, Jul 21, 2014 at 7:13 AM, Pengfei Yuan <0xcool...@gmail.com> wrote: >>>> Hi, >>>> >>>> This patch tunes optimization options based on profile data: >>>> * Disable PGO options if profile is not available or empty. >>>> * Optimize for size if profile is available but empty. >>> >>> Err ... these don't seem interesting cases to "optimize" for? >>> >>> Richard.