From: Tom de Vries <Tom_deVries@mentor.com>
To: Richard Biener <richard.guenther@gmail.com>,
Thomas Schwinge <thomas@codesourcery.com>
Cc: "gcc-patches@gnu.org" <gcc-patches@gnu.org>
Subject: Re: [RFC, PR66873] Use graphite for parloops
Date: Thu, 16 Jul 2015 11:41:00 -0000 [thread overview]
Message-ID: <55A7935A.60401@mentor.com> (raw)
In-Reply-To: <CAFiYyc2mLNFeX_==PxTUih2BYdmQ9bOG2TGuJAjUddB35_57-g@mail.gmail.com>
On 16/07/15 12:23, Richard Biener wrote:
> On Thu, Jul 16, 2015 at 12:19 PM, Thomas Schwinge
> <thomas@codesourcery.com> wrote:
>> Hi Tom!
>>
>> On Thu, 16 Jul 2015 10:46:00 +0200, Richard Biener <richard.guenther@gmail.com> wrote:
>>> On Wed, Jul 15, 2015 at 10:26 PM, Tom de Vries <Tom_deVries@mentor.com> wrote:
>>>> I tried to parallelize this fortran test-case (based on autopar/outer-1.c),
>>>> [...]
>>
>>>> So I wondered, why not always use the graphite dependency analysis in
>>>> parloops. (Of course you could use -floop-parallelize-all, but that also
>>>> changes the heuristic). So I wrote a patch for parloops to use graphite
>>>> dependency analysis by default (so without -floop-parallelize-all), but
>>>> while testing found out that all the reduction test-cases started failing
>>>> because the modifications graphite makes to the code messes up the parloops
>>>> reduction analysis.
>>>>
>>>> Then I came up with this patch, which:
>>>> - first runs a parloops pass, restricted to reduction loops only,
>>>> - then runs graphite dependency analysis
>>>> - followed by a normal parloops pass run.
>>>>
>>>> This way, we get to both:
>>>> - compile the reduction testcases as before, and
>>>> - profit from the better graphite dependency analysis otherwise.
>>
>>> graphite dependence analysis is too slow to be enabled unconditionally.
>>> (read: hours in some simple cases - see bugzilla)
>>
>> Haha, "cool"! ;-)
>>
>> Maybe it is still reasonable to use graphite to analyze the code inside
>> OpenACC kernels regions -- maybe such code can reasonably be expected to
>> not have the properties that make its analysis lengthy? So, Tom, could
>> you please identify and check such PRs, to get an understanding of what
>> these properties are?
>
> Like the one in PR62113 or 53852 or 59121.
PR62113 and PR59121 do not reproduce for me on trunk.
PR53852 does reproduce for me (to the point that I had to reset my laptop).
Thanks,
- Tom
next prev parent reply other threads:[~2015-07-16 11:20 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-15 22:18 Tom de Vries
2015-07-16 8:48 ` Richard Biener
2015-07-16 10:25 ` Thomas Schwinge
2015-07-16 10:28 ` Richard Biener
2015-07-16 10:41 ` Richard Biener
2015-07-26 22:54 ` Tom de Vries
2015-07-27 5:41 ` Sebastian Pop
2015-07-16 11:41 ` Tom de Vries [this message]
2015-07-20 18:53 ` Sebastian Pop
2015-07-21 0:22 ` Tom de Vries
2015-07-20 18:54 ` Sebastian Pop
2015-07-21 5:59 ` Tom de Vries
2015-07-21 14:35 ` Tom de Vries
2015-07-21 19:08 ` Sebastian Pop
2015-07-22 11:02 ` Richard Biener
2015-07-22 11:18 ` Richard Biener
2015-07-22 16:04 ` [PATCH] Don't allow unsafe reductions in graphite Tom de Vries
2015-07-23 10:51 ` Richard Biener
2015-07-24 20:37 ` Sebastian Pop
2015-07-25 11:41 ` Tom de Vries
2015-07-22 16:38 ` [PATCH] Check TYPE_OVERFLOW_WRAPS for parloops reductions Tom de Vries
2015-07-23 10:54 ` Richard Biener
2015-07-24 10:43 ` [committed] Remove xfail in autopar/uns-outer-4.c Tom de Vries
2015-07-24 11:54 ` [PATCH] Add FIXED_POINT_TYPE_OVERFLOW_WRAPS_P Tom de Vries
2015-07-22 15:33 ` [PATCH] Document ftrapv/fwrapv interaction Tom de Vries
2015-07-23 10:39 ` Richard Biener
2015-07-23 10:42 ` Richard Biener
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