And the patch.

On Fri, Jun 23, 2017 at 11:24 AM, Bin.Cheng <amker.cheng@gmail.com> wrote:
> On Tue, Jun 20, 2017 at 12:34 PM, Richard Biener
> <richard.guenther@gmail.com> wrote:
>> On Tue, Jun 20, 2017 at 11:18 AM, Bin.Cheng <amker.cheng@gmail.com> wrote:
>>> On Fri, Jun 16, 2017 at 11:10 AM, Richard Biener
>>> <richard.guenther@gmail.com> wrote:
>>>> On Mon, Jun 12, 2017 at 7:03 PM, Bin Cheng <Bin.Cheng@arm.com> wrote:
>>>>> Hi,
>>>>> This patch checks and records if partition can be executed in parallel by
>>>>> looking if there exists data dependence cycles.  The information is needed
>>>>> for distribution because the idea is to distribute parallel type partitions
>>>>> away from sequential ones.  I believe current distribution doesn't work
>>>>> very well because it does blind distribution/fusion.
>>>>> Bootstrap and test on x86_64 and AArch64.  Is it OK?
>>>>
>>>> +  /* In case of no data dependence.  */
>>>> +  if (DDR_ARE_DEPENDENT (ddr) == chrec_known)
>>>> +    return false;
>>>> +  /* Or the data dependence can be resolved by compilation time alias
>>>> +     check.  */
>>>> +  else if (!alias_sets_conflict_p (get_alias_set (DR_REF (dr1)),
>>>> +                                  get_alias_set (DR_REF (dr2))))
>>>> +    return false;
>>>>
>>>> dependence analysis should use TBAA already, in which cases do you need this?
>>>> It seems to fall foul of the easy mistake of not honoring GCCs memory model
>>>> as well ... see dr_may_alias_p.
>>> I see.  Patch updated with this branch removed.
>>>
>>>>
>>>> +  /* Further check if any data dependence prevents us from executing the
>>>> +     partition parallelly.  */
>>>> +  EXECUTE_IF_SET_IN_BITMAP (partition->reads, 0, i, bi)
>>>> +    {
>>>> +      dr1 = (*datarefs_vec)[i];
>>>> +      EXECUTE_IF_SET_IN_BITMAP (partition->writes, 0, j, bj)
>>>> +       {
>>>>
>>>> what about write-write dependences?
>>>>
>>>> +  EXECUTE_IF_SET_IN_BITMAP (partition->reads, 0, i, bi)
>>>> +    {
>>>> +      dr1 = (*datarefs_vec)[i];
>>>> +      EXECUTE_IF_SET_IN_BITMAP (partition->writes, i + 1, j, bj)
>>>> +       {
>>>> +         dr2 = (*datarefs_vec)[j];
>>>> +         /* Partition can only be executed sequentially if there is any
>>>> +            data dependence cycle.  */
>>>>
>>>> exact copy of the loop nest follows?!  Maybe you meant to iterate
>>>> over writes in the first loop.
>>> Yes, this is a copy-paste typo.  Patch is also simplified because
>>> read/write are recorded together now.  Is it OK?
>>
>> Ok.
> Sorry I have to update this patch because one of my mistake.  I didn't
> update partition type when fusing them.  For some partition fusion,
> the update is necessary otherwise we end up with inaccurate type and
> inaccurate fusion later.  Is it Ok?
>
> Thanks,
> bin
> 2017-06-20  Bin Cheng  <bin.cheng@arm.com>
>
>     * tree-loop-distribution.c (enum partition_type): New.
>     (struct partition): New field type.
>     (partition_merge_into): Add parameter.  Update partition type.
>     (data_dep_in_cycle_p, update_type_for_merge): New functions.
>     (build_rdg_partition_for_vertex): Compute partition type.
>     (rdg_build_partitions): Dump partition type.
>     (distribute_loop): Update calls to partition_merge_into.