From: Yuri Rumyantsev <ysrumyan@gmail.com>
To: Richard Biener <richard.guenther@gmail.com>
Cc: gcc-patches <gcc-patches@gcc.gnu.org>,
Igor Zamyatin <izamyatin@gmail.com>
Subject: Re: [PATCH] Unswitching outer loops.
Date: Thu, 23 Jul 2015 15:21:00 -0000 [thread overview]
Message-ID: <CAEoMCqTX7Jw+uLy9MzrsygBKNjLKk2hfZKrCV7exD9kCD1SWAg@mail.gmail.com> (raw)
In-Reply-To: <CAFiYyc3P5Pzy+dbJp1_j6wo8NKJFQGJJP_tntt5vX74xwXo0cw@mail.gmail.com>
Hi Richard,
I checked that both test-cases from 23855 are sucessfully unswitched
by proposed patch. I understand that it does not catch deeper loop
nest as
for (i=0; i<10; i++)
for (j=0;j<n;j++)
for (k=0;k<20;k++)
...
but duplication of middle-loop does not look reasonable.
Here is dump for your second test-case:
void foo(int *ie, int *je, double *x)
{
int i, j;
for (j=0; j<*je; ++j)
for (i=0; i<*ie; ++i)
x[i+j] = 0.0;
}
grep -i unswitch t6.c.119t.unswitch
;; Unswitching outer loop
Yuri.
2015-07-14 14:06 GMT+03:00 Richard Biener <richard.guenther@gmail.com>:
> On Fri, Jul 10, 2015 at 12:02 PM, Yuri Rumyantsev <ysrumyan@gmail.com> wrote:
>> Hi All,
>>
>> Here is presented simple transformation which tries to hoist out of
>> outer-loop a check on zero trip count for inner-loop. This is very
>> restricted transformation since it accepts outer-loops with very
>> simple cfg, as for example:
>> acc = 0;
>> for (i = 1; i <= m; i++) {
>> for (j = 0; j < n; j++)
>> if (l[j] == i) { v[j] = acc; acc++; };
>> acc <<= 1;
>> }
>>
>> Note that degenerative outer loop (without inner loop) will be
>> completely deleted as dead code.
>> The main goal of this transformation was to convert outer-loop to form
>> accepted by outer-loop vectorization (such test-case is also included
>> to patch).
>>
>> Bootstrap and regression testing did not show any new failures.
>>
>> Is it OK for trunk?
>
> I think this is
>
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=23855
>
> as well. It has a patch adding a invariant loop guard hoisting
> phase to loop-header copying. Yeah, it needs updating to
> trunk again I suppose. It's always non-stage1 when I come
> back to that patch.
>
> Your patch seems to be very specific and only handles outer
> loops of innermost loops.
>
> Richard.
>
>> ChangeLog:
>> 2015-07-10 Yuri Rumyantsev <ysrumyan@gmail.com>
>>
>> * tree-ssa-loop-unswitch.c: Include "tree-cfgcleanup.h" and
>> "gimple-iterator.h", add prototype for tree_unswitch_outer_loop.
>> (tree_ssa_unswitch_loops): Add invoke of tree_unswitch_outer_loop.
>> (tree_unswitch_outer_loop): New function.
>>
>> gcc/testsuite/ChangeLog:
>> * gcc.dg/tree-ssa/unswitch-outer-loop-1.c: New test.
>> * gcc.dg/vect/vect-outer-simd-3.c: New test.
next prev parent reply other threads:[~2015-07-23 14:45 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-10 10:03 Yuri Rumyantsev
2015-07-14 11:07 ` Richard Biener
2015-07-23 15:21 ` Yuri Rumyantsev [this message]
2015-07-28 11:00 ` Richard Biener
2015-07-31 12:07 ` Yuri Rumyantsev
2015-07-31 15:54 ` Jeff Law
2015-08-03 7:27 ` Richard Biener
[not found] ` <CAEoMCqSorkh1WmFtVB_huC2hbcVr8uc1EYaRaNVe1g+5hVuzPw@mail.gmail.com>
[not found] ` <CAFiYyc1nCCyF-4BH2hPWkKpmXnaQFQ34RMM5TTuHjZxZ25crrA@mail.gmail.com>
[not found] ` <CAEoMCqSRsER9ZGgnX9eJgZJyN4EwkpxzWWk1FHRxWNiEW0HVCg@mail.gmail.com>
[not found] ` <CAFiYyc2O9i690A0LZ0+jEOP8nkyz8Btc0YAb469aMgnRaVsmsQ@mail.gmail.com>
2015-09-30 11:40 ` Yuri Rumyantsev
2015-10-05 10:57 ` Richard Biener
2015-10-05 13:13 ` Yuri Rumyantsev
2015-10-06 7:59 ` Richard Biener
2015-10-06 11:41 ` Yuri Rumyantsev
2015-10-06 12:21 ` Richard Biener
2015-10-07 9:53 ` Yuri Rumyantsev
2015-10-07 15:26 ` Yuri Rumyantsev
2015-10-08 12:31 ` Richard Biener
2015-10-09 19:05 ` H.J. Lu
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