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

[Richard Biener <richard.guenther@gmail.com>]

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...)

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.