Re: [PATCH GCC8][31/33]Set range information for niter bound of vectorized loop

["Bin.Cheng" <amker.cheng@gmail.com>]

On Wed, May 24, 2017 at 2:48 PM, Richard Biener
<richard.guenther@gmail.com> wrote:
> On Mon, May 22, 2017 at 7:13 PM, Bin.Cheng <amker.cheng@gmail.com> wrote:
>> On Fri, May 19, 2017 at 1:51 PM, Richard Biener
>> <richard.guenther@gmail.com> wrote:
>>> On Mon, May 15, 2017 at 5:58 PM, Bin.Cheng <amker.cheng@gmail.com> wrote:
>>>> On Thu, May 11, 2017 at 12:02 PM, Richard Biener
>>>> <richard.guenther@gmail.com> wrote:
>>>>> On Tue, Apr 18, 2017 at 12:54 PM, Bin Cheng <Bin.Cheng@arm.com> wrote
>>>>>> Hi,
>>>>>> Based on vect_peeling algorithm, we know for sure that vectorized loop must iterates at least once.
>>>>>> This patch sets range information for niter bounds of vectorized loop.  This helps niter analysis,
>>>>>> so iv elimination too.
>>>>>> Is it OK?
>>>>>
>>>>>        niters_vector = force_gimple_operand (niters_vector, &stmts, true, var);
>>>>>        gsi_insert_seq_on_edge_immediate (pe, stmts);
>>>>> +      /* Peeling algorithm guarantees that vector loop bound is at least ONE,
>>>>> +        we set range information to make niters analyzer's life easier.  */
>>>>> +      if (TREE_CODE (niters_vector) == SSA_NAME)
>>>>> +       set_range_info (niters_vector, VR_RANGE, build_int_cst (type, 1),
>>>>> +                       fold_build2 (RSHIFT_EXPR, type,
>>>>> +                                    TYPE_MAX_VALUE (type), log_vf));
>>>>>
>>>>> if all of niters_vector folds to an original SSA name then
>>>>> niters_vector after gimplification
>>>>> is not a new SSA name and thus you can't set range-info on it.
>>>>>
>>>>> Likewise for the other case where LOOP_VINFO_NITERS is just an SSA name.
>>>> Hi,
>>>> This is updated patch.  It checks whether the result ssa name is newly
>>>> created tmp and only sets range information if so.
>>>>
>>>> Is it OK?
>>>
>>> A better way to check whether the SSA name is new is to see if 'stmts'
>>> filled by force_gimple_operand is non-empty.
>> Hi,
>> Here is updated patch checking empty gimple_seq.  Is it OK?
>
> Ok.  As a bonus you could have used wide-ints to feed set_range_info
> (not sure if wide_int_ref & allows you to pass '1' literally...)
Patch applied @r248958.  Being lazy not using wide_int here, I will
pick up this after current work.

Thanks,
bin
>
> Richard.
>
>> Thanks,
>> bin
>>>
>>> Richard.
>>>
>>>> Thanks,
>>>> bin
>>>>
>>>> 2017-04-11  Bin Cheng  <bin.cheng@arm.com>
>>>>
>>>>     * tree-vectorizer.h (vect_build_loop_niters): New parameter.
>>>>     * tree-vect-loop-manip.c (vect_build_loop_niters): New parameter.
>>>>     Set true to new parameter if new ssa variable is defined.
>>>>     (vect_gen_vector_loop_niters): Refactor.  Set range information
>>>>     for the new vector loop bound variable.
>>>>     (vect_do_peeling): Ditto.
>>>>
>>>>>
>>>>> Richard.
>>>>>
>>>>>> Thanks,
>>>>>> bin
>>>>>> 2017-04-11  Bin Cheng  <bin.cheng@arm.com>
>>>>>>
>>>>>>         * tree-vect-loop-manip.c (vect_gen_vector_loop_niters): Refactor.
>>>>>>         Set range information for vector loop bound variable.
>>>>>>         (vect_do_peeling): Ditto.