This is the mail archive of the
mailing list for the GCC project.
Re: [PATCH] alternative hirate for builtin_expert
- From: Ramana Radhakrishnan <ramrad01 at arm dot com>
- To: Rong Xu <xur at google dot com>
- Cc: Jan Hubicka <hubicka at ucw dot cz>, GCC Patches <gcc-patches at gcc dot gnu dot org>, David Li <davidxl at google dot com>
- Date: Fri, 04 Oct 2013 14:05:17 +0100
- Subject: Re: [PATCH] alternative hirate for builtin_expert
- Authentication-results: sourceware.org; auth=none
- References: <CAF1bQ=TH5+Qfd1MsAUDBJj+F-zizymTTGh7HxyuXUbaPqd-mng at mail dot gmail dot com> <CAF1bQ=Q_eiCz8AYkU-c=Xu7quQ0vy8eP=pi9QZt+QOF4vicnsg at mail dot gmail dot com> <20131002160827 dot GB7181 at kam dot mff dot cuni dot cz> <CAF1bQ=Snvzzmm=AEr-crrKhopRugKbcExH+wFCyCcgZZHz+Uow at mail dot gmail dot com> <20131002213102 dot GE7181 at kam dot mff dot cuni dot cz> <CAF1bQ=R+oNesEedf_8-oVtQBgWSZMvEegtY-Z_LgsMfVj4qpqg at mail dot gmail dot com>
On 10/02/13 23:49, Rong Xu wrote:
Here is the new patch. Honaz: Could you take a look?
On Wed, Oct 2, 2013 at 2:31 PM, Jan Hubicka <email@example.com> wrote:
Thanks for the suggestion. This is much cleaner than to use binary parameter.
Just want to make sure I understand it correctly about the orginal hitrate:
you want to retire the hitrate in PRED_BUILTIN_EXPECT and always use
the one specified in the biniltin-expect-probability parameter.
Should I use 90% as the default? It's hard to fit current value 0.9996
in percent form.
Yes, 90% seems fine. The original value was set quite arbitrarily and no real
performance study was made as far as I know except yours. I think users that
are sure they use expect to gueard completely cold edges may just use 100%
instead of 0.9996, so I would not worry much about the precision.
OK with that change.
This broke arm-linux-gnueabihf building libstdc++-v3. I haven't dug
further yet but still reducing the testcase.
Can you please deal with this appropriately ?