This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [Google/4-8] Support for user-guided feedback-directed library optimization
- From: Teresa Johnson <tejohnson at google dot com>
- To: Xinliang David Li <davidxl at google dot com>
- Cc: Andi Kleen <andi at firstfloor dot org>, GCC Patches <gcc-patches at gcc dot gnu dot org>, Jan Hubicka <hubicka at ucw dot cz>
- Date: Wed, 14 May 2014 16:19:05 -0700
- Subject: Re: [Google/4-8] Support for user-guided feedback-directed library optimization
- Authentication-results: sourceware.org; auth=none
- References: <CAAe5K+U7wTXua5=96kqA47UWpPhuY-X3WW9NefpvXOUCffVQ7g at mail dot gmail dot com> <874n0yic04 dot fsf at tassilo dot jf dot intel dot com> <CAAe5K+WVvBp7ZEB9Y69FHFYbSsW11JEPmy471Vby+vpojQSWoQ at mail dot gmail dot com> <20140510215957 dot GA1873 at two dot firstfloor dot org> <CAAkRFZJDfHy8ThCSvEAtKk472-6U-iD8V5fFrY7Q72wEDhOzJQ at mail dot gmail dot com>
Hi Andi,
I'll work on putting together some good documentation before sending
this and follow-on support to trunk. As David mentions, the plan for
the subsequent patch to add the hooks that enable users to trigger
gcc's value profiling on particular variables. This first patch simply
allows users to define their own profiling routines, that
automatically only get compiled in on the profile-gen build and have
the results automatically applied to the profile-use compile via the
gcda file.
Thanks,
Teresa
On Sat, May 10, 2014 at 3:44 PM, Xinliang David Li <davidxl@google.com> wrote:
> User directed value profiling will also be supported but not in this patch.
>
> David
>
> On May 10, 2014 2:59 PM, "Andi Kleen" <andi@firstfloor.org> wrote:
>>
>> On Fri, May 09, 2014 at 08:11:40PM -0700, Teresa Johnson wrote:
>> > Thanks for catching that, I will fix it.
>>
>> BTW I first misunderstood the goal of you patch.
>>
>> (probably because there is no documentation ... something that should
>> also be fixed)
>>
>> I originally thought it was a way to let user code use the value profiling
>> libgcov functions to profile arbitary values, and then later use the
>> most common value for some optimization.
>>
>> But instead it seems to be only an (somewhat over complicated) IO
>> mechanism to let user programs write arbitrary values to the gcov file and
>> pass it back.
>>
>> I think I would find the first more useful.
>>
>> -Andi
>>
>
--
Teresa Johnson | Software Engineer | tejohnson@google.com | 408-460-2413