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Re: [PATCH] Redesign jump threading profile updates
- From: Teresa Johnson <tejohnson at google dot com>
- To: Jeff Law <law at redhat dot com>
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Jan Hubicka <hubicka at ucw dot cz>, David Li <davidxl at google dot com>
- Date: Mon, 7 Jul 2014 14:22:34 -0700
- Subject: Re: [PATCH] Redesign jump threading profile updates
- Authentication-results: sourceware.org; auth=none
- References: <CAAe5K+XMKuBvrA2zbSdA38nq+KiezseL6z_4KayvV322VmJtZQ at mail dot gmail dot com> <534F6901 dot 7090700 at redhat dot com> <CAAe5K+UrMtD=6tQYxNYhJ1k2owMbBRFKf87d75bFgoNo9kowGQ at mail dot gmail dot com> <CAAe5K+WU5iutzdZxvt9Rq8mv1wse=7mKMXW8N2+BMN+ouDSJqw at mail dot gmail dot com>
Ping. Jeff, any update on when you can look at this?
On Tue, May 27, 2014 at 7:10 AM, Teresa Johnson <email@example.com> wrote:
> On Thu, Apr 17, 2014 at 6:23 AM, Teresa Johnson <firstname.lastname@example.org> wrote:
>> On Wed, Apr 16, 2014 at 10:39 PM, Jeff Law <email@example.com> wrote:
>>> On 03/26/14 17:44, Teresa Johnson wrote:
>>>> Recently I discovered that the profile updates being performed by jump
>>>> threading were incorrect in many cases, particularly in the case where
>>>> the threading path contains a joiner. Some of the duplicated
>>>> blocks/edges were not getting any counts, leading to incorrect
>>>> function splitting and other downstream optimizations, and there were
>>>> other insanities as well. After making a few attempts to fix the
>>>> handling I ended up completely redesigning the profile update code,
>>>> removing a few places throughout the code where it was attempting to
>>>> do some updates.
>>> The profile updates in that code is a mess. It's never really been looked
>>> at in any systematic way, what's there is ad-hoc and usually in response to
>>> someone mentioning the profile data was incorrectly updated. As we rely
>>> more and more on that data the ad-hoc updating is going to cause us more and
>>> more pain.
>>> So any work in this space is going to be greatly appreciated.
>>> I'll have to look at this in some detail. But I wanted you to know I was
>>> aware of the work and it's in my queue.
>> Great, thanks for the update! I realize that it is not a trivial
>> change so it would take some time to get through. Hopefully it should
>> address the ongoing profile fixup issues.
>> Teresa Johnson | Software Engineer | firstname.lastname@example.org | 408-460-2413
> Teresa Johnson | Software Engineer | email@example.com | 408-460-2413
Teresa Johnson | Software Engineer | firstname.lastname@example.org | 408-460-2413