On 2013-01-22 4:40 PM, Robert O'Callahan wrote:
On Wed, Jan 23, 2013 at 4:31 AM, Ehsan Akhgari <ehsan.akhg...@gmail.com <mailto:ehsan.akhg...@gmail.com>> wrote:But note that unless a given code path is examined throughout the profiling phase of a PGO build, PGO will probably have negligible effect on it, if any. The PGO compiler looks for hot code paths and tries to optimize those, so for example if the awesomebar doesn't get examined during the profiling (which it isn't), it is extremely unlikely that turning off PGO on the code responsible for it would have any noticeable change on performance. I don't think this is a safe assumption. Our PGO builds not only do PGO but also "Link Time Code Generation" which enables cross-module optimizations. I have seen code being heavily optimized under PGO that I would not have expected to be significant in our PGO profile. It wouldn't be that hard to do an experiment to test the impact of PGO/LTCG on code that's not in the profile.
Yeah, that would probably be an interesting experiment. Cheers, Ehsan _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
