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). Diego. _______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
