Patch ping (Re: [PATCH PR82965/PR83991]Fix invalid profile count in vectorization peeling)
Paul Hua
paul.hua.gm@gmail.com
Mon Mar 12 02:00:00 GMT 2018
On Fri, Mar 9, 2018 at 10:51 PM, Bin.Cheng <amker.cheng@gmail.com> wrote:
> On Fri, Mar 9, 2018 at 10:25 AM, Paul Hua <paul.hua.gm@gmail.com> wrote:
>> It's looks fixed
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82965#c12 on mips64el.
> Hmm, is it fixed? or is it exposed now on mips64el? I read the latter
> from the comment.
It is fixed, Bootstrap and test passed on mips64el.
Thanks,
Paul Hua
> I think the issue is like explained, but haven't dug into when/why it
> is triggered in vect_peeling only for some targets.
> Honza asked couple questions about my patch offline, I will revisit
> the patch, see how to address
> his concern.
>
> Thanks,
> bin
>>
>> Thanks.
>>
>> On Mon, Feb 26, 2018 at 8:02 PM, Bin.Cheng <amker.cheng@gmail.com> wrote:
>>> Ping^2
>>>
>>> Thanks,
>>> bin
>>>
>>> On Mon, Feb 19, 2018 at 5:14 PM, Jakub Jelinek <jakub@redhat.com> wrote:
>>>> Hi!
>>>>
>>>> Honza, do you think you could have a look at this P1 fix?
>>>>
>>>> Thanks.
>>>>
>>>> On Wed, Jan 31, 2018 at 10:03:51AM +0000, Bin Cheng wrote:
>>>>> Hi,
>>>>> This patch fixes invalid profile count information in vectorization peeling.
>>>>> Current implementation is a bit confusing for me since it tries to compute
>>>>> an overall probability based on scaling probability and change of estimated
>>>>> niters. This patch does it in two steps. Firstly it does the scaling, then
>>>>> it adjusts to new estimated niters by simply adjusting loop's latch count
>>>>> information; scaling the loop's count information by the proportion
>>>>> new_estimated_niters/old_estimate_niters. Of course we have to adjust loop
>>>>> latch's count information back after scaling.
>>>>>
>>>>> Bootstrap and test on x86_64 and AArch64. gcc.dg/vect/pr79347.c is fixed
>>>>> for both PR82965 and PR83991. Is this OK?
>>>>>
>>>>> Thanks,
>>>>> bin
>>>>>
>>>>> 2018-01-30 Bin Cheng <bin.cheng@arm.com>
>>>>>
>>>>> PR tree-optimization/82965
>>>>> PR tree-optimization/83991
>>>>> * cfgloopmanip.c (scale_loop_profile): Further scale loop's profile
>>>>> information if the loop was predicted to iterate too many times.
>>>>
>>>>> diff --git a/gcc/cfgloopmanip.c b/gcc/cfgloopmanip.c
>>>>> index b9b76d8..1f560b8 100644
>>>>> --- a/gcc/cfgloopmanip.c
>>>>> +++ b/gcc/cfgloopmanip.c
>>>>> @@ -509,7 +509,7 @@ scale_loop_profile (struct loop *loop, profile_probability p,
>>>>> gcov_type iteration_bound)
>>>>> {
>>>>> gcov_type iterations = expected_loop_iterations_unbounded (loop);
>>>>> - edge e;
>>>>> + edge e, preheader_e;
>>>>> edge_iterator ei;
>>>>>
>>>>> if (dump_file && (dump_flags & TDF_DETAILS))
>>>>> @@ -521,77 +521,66 @@ scale_loop_profile (struct loop *loop, profile_probability p,
>>>>> (int)iteration_bound, (int)iterations);
>>>>> }
>>>>>
>>>>> + /* Scale the probabilities. */
>>>>> + scale_loop_frequencies (loop, p);
>>>>> +
>>>>> /* See if loop is predicted to iterate too many times. */
>>>>> - if (iteration_bound && iterations > 0
>>>>> - && p.apply (iterations) > iteration_bound)
>>>>> + if (iteration_bound == 0 || iterations <= 0
>>>>> + || p.apply (iterations) <= iteration_bound)
>>>>> + return;
>>>>> +
>>>>> + e = single_exit (loop);
>>>>> + preheader_e = loop_preheader_edge (loop);
>>>>> + profile_count count_in = preheader_e->count ();
>>>>> + if (e && preheader_e
>>>>> + && count_in > profile_count::zero ()
>>>>> + && loop->header->count.initialized_p ())
>>>>> {
>>>>> - /* Fixing loop profile for different trip count is not trivial; the exit
>>>>> - probabilities has to be updated to match and frequencies propagated down
>>>>> - to the loop body.
>>>>> -
>>>>> - We fully update only the simple case of loop with single exit that is
>>>>> - either from the latch or BB just before latch and leads from BB with
>>>>> - simple conditional jump. This is OK for use in vectorizer. */
>>>>> - e = single_exit (loop);
>>>>> - if (e)
>>>>> - {
>>>>> - edge other_e;
>>>>> - profile_count count_delta;
>>>>> + edge other_e;
>>>>> + profile_count count_delta;
>>>>>
>>>>> - FOR_EACH_EDGE (other_e, ei, e->src->succs)
>>>>> - if (!(other_e->flags & (EDGE_ABNORMAL | EDGE_FAKE))
>>>>> - && e != other_e)
>>>>> - break;
>>>>> + FOR_EACH_EDGE (other_e, ei, e->src->succs)
>>>>> + if (!(other_e->flags & (EDGE_ABNORMAL | EDGE_FAKE))
>>>>> + && e != other_e)
>>>>> + break;
>>>>>
>>>>> - /* Probability of exit must be 1/iterations. */
>>>>> - count_delta = e->count ();
>>>>> - e->probability = profile_probability::always ()
>>>>> + /* Probability of exit must be 1/iterations. */
>>>>> + count_delta = e->count ();
>>>>> + e->probability = profile_probability::always ()
>>>>> .apply_scale (1, iteration_bound);
>>>>> - other_e->probability = e->probability.invert ();
>>>>> - count_delta -= e->count ();
>>>>> -
>>>>> - /* If latch exists, change its count, since we changed
>>>>> - probability of exit. Theoretically we should update everything from
>>>>> - source of exit edge to latch, but for vectorizer this is enough. */
>>>>> - if (loop->latch
>>>>> - && loop->latch != e->src)
>>>>> - {
>>>>> - loop->latch->count += count_delta;
>>>>> - }
>>>>> - }
>>>>> + other_e->probability = e->probability.invert ();
>>>>>
>>>>> /* Roughly speaking we want to reduce the loop body profile by the
>>>>> difference of loop iterations. We however can do better if
>>>>> we look at the actual profile, if it is available. */
>>>>> - p = p.apply_scale (iteration_bound, iterations);
>>>>> -
>>>>> - if (loop->header->count.initialized_p ())
>>>>> - {
>>>>> - profile_count count_in = profile_count::zero ();
>>>>> + p = profile_probability::always ();
>>>>>
>>>>> - FOR_EACH_EDGE (e, ei, loop->header->preds)
>>>>> - if (e->src != loop->latch)
>>>>> - count_in += e->count ();
>>>>> -
>>>>> - if (count_in > profile_count::zero () )
>>>>> - {
>>>>> - p = count_in.probability_in (loop->header->count.apply_scale
>>>>> - (iteration_bound, 1));
>>>>> - }
>>>>> - }
>>>>> + count_in = count_in.apply_scale (iteration_bound, 1);
>>>>> + p = count_in.probability_in (loop->header->count);
>>>>> if (!(p > profile_probability::never ()))
>>>>> p = profile_probability::very_unlikely ();
>>>>> - }
>>>>>
>>>>> - if (p >= profile_probability::always ()
>>>>> - || !p.initialized_p ())
>>>>> - return;
>>>>> + if (p >= profile_probability::always ()
>>>>> + || !p.initialized_p ())
>>>>> + return;
>>>>>
>>>>> - /* Scale the actual probabilities. */
>>>>> - scale_loop_frequencies (loop, p);
>>>>> - if (dump_file && (dump_flags & TDF_DETAILS))
>>>>> - fprintf (dump_file, ";; guessed iterations are now %i\n",
>>>>> - (int)expected_loop_iterations_unbounded (loop));
>>>>> + /* If latch exists, change its count, since we changed
>>>>> + probability of exit. Theoretically we should update everything from
>>>>> + source of exit edge to latch, but for vectorizer this is enough. */
>>>>> + if (loop->latch && loop->latch != e->src)
>>>>> + loop->latch->count += count_delta;
>>>>> +
>>>>> + /* Scale the probabilities. */
>>>>> + scale_loop_frequencies (loop, p);
>>>>> +
>>>>> + /* Change latch's count back. */
>>>>> + if (loop->latch && loop->latch != e->src)
>>>>> + loop->latch->count -= count_delta;
>>>>> +
>>>>> + if (dump_file && (dump_flags & TDF_DETAILS))
>>>>> + fprintf (dump_file, ";; guessed iterations are now %i\n",
>>>>> + (int)expected_loop_iterations_unbounded (loop));
>>>>> + }
>>>>> }
>>>>>
>>>>> /* Recompute dominance information for basic blocks outside LOOP. */
>>>>
>>>>
>>>> Jakub
More information about the Gcc-patches
mailing list