On Tue, Oct 22, 2013 at 2:28 PM, Diego Novillo <[email protected]> wrote:
> On Tue, Oct 22, 2013 at 5:06 PM, Chandler Carruth <[email protected]> > wrote: > > > > On Tue, Oct 22, 2013 at 1:58 PM, Bob Wilson <[email protected]> > wrote: > >> > >> I really like GCC's -fprofile-generate and -fprofile-use, except I don't > >> think we should reuse those names for something that works differently. > My > >> overall preference would be something like this (using those names as > >> placeholders): > >> > >> -fprofile-generate=<instrumentation-style> > >> -fprofile-use=<profile-style> > >> > >> e.g., "-fprofile-use=auto". That would at least unify the new options. > >> In fact, we may even be able to reuse those option names with > -fprofile-use > >> being a synonym for -fprofile-use=gcc, which matches gcc's option. I'm > not > >> at all familiar with how that option actually works in gcc, so I can't > say > >> whether that would make sense. > > > > > > I don't think we can re-use '-fprofile-use' in a way different from GCC > > here. GCC accepts it as "-fprofile-use=/path/..." and i could call my > > profile file "auto" or "gcc" or "clang" and expect it to work. > > > > I think it is best for instrumentation-based profiling to use > > '-fprofile-generate' and '-fprofile-use' just like GCC does, if with > > different file formats, etc. > > Agreed. > > > I don't see in flags in upstream GCC regarding sample-driven profiling, > but > > "auto" I think is actively harmful in the name. There is nothing > > intrinsically automatic about it. It is "external" in the sense that it > > isn't from compiled-in instrumentation, but I don't see any reason for > > "auto" to indicate that to the user. > > GCC (well the Google branch now) uses -fauto-profile for the > sample-driven profiling. The external profiler actually generates a > gcov file. The two options -fprofile-generate and -fprofile-use are > strictly for instrumentation based profiling. Our internal users are > already using -fauto-profile in their builds. > > Dehao (CCd) tells me that the option was initially named > -fsample-profile, but they then renamed it to -fauto-profile. > > > I think for now, we should put this functionality behind a specific flag > > whose name is indicative of the user's expected behavior. The best idea > I've > > seen is "-fsample-profile=/path/..." but I'd love to hear better > > suggestions. > > I don't really have better names. -fsample-profile and -fauto-profile > are both the same to me. The name -fauto-profile has the slight > advantage that it can serve as a more general flag name, with the > actual profiling style automatically detected by the format of the > input file. But, I don't really care all that much. > > Having said that, I can also see -fprofile-use=filename being smart > enough to know what type of profile it's getting by examining the > signature of "filename". This is contemplated in my LLVM patch. The > pass instantiates a different reader according to the type of file it > detects (right now it does nothing of the sort, however). > My $0.02 having just read the recent discussion: particularly if/when -fprofile-use=filename is smart enough to detect the type of profile, instead of having -f*-profile options like -fsample-profile, perhaps -fprofile-type=<kind> (e.g. -fprofile-type=sample, -fprofile-type=gcc, etc--or -fprofile-kind=<kind> instead of -fprofile-type) where the type defaults to GCC style... or later to whatever -fprofile-use= guesses the file's format to be. It also gives pretty good symmetry to -fprofile-generate= and -fprofile-use= Cheers, Kaelyn > > > Diego. > _______________________________________________ > cfe-commits mailing list > [email protected] > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits >
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