Re: [PATCH GCC][4/6]Relax minimal segment length of DR_B for merging alias check

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

On Thu, May 25, 2017 at 5:16 PM, Bin.Cheng <amker.cheng@gmail.com> wrote:
> On Tue, May 23, 2017 at 5:23 PM, Bin Cheng <Bin.Cheng@arm.com> wrote:
>> Hi,
>> As commented in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80815#c1,
>> We can relax minimal segment length of DR_B for merging.  With this change,
>> the new test can be improved to only one alias check.  Note the
>> condition is still accurate after this patch, it won't introduce false
>> alias.
>> Bootstrap and test on x86_64 and AArch64, is it OK?
> Updated patch wrto change of previous patch.
>
> Bootstrap and test on x86_64 and AArch64.

Please omit unnecessary braces.  Ok with that change.

Note that

          if (tree_fits_uhwi_p (dr_b1->seg_len))
            {
              min_seg_len_b = dr_b1->seg_len;
              if (tree_int_cst_sign_bit (dr_b1->seg_len))
                min_seg_len_b = wi::neg (min_seg_len_b);

the tree_fits_uhwi_p check is somewhat bogus now that min_seg_len_b is
a wide-int.
It should probably be changed to TREE_CODE (dr_b1->seg_len) == INTEGER_CST
which also means  that

              min_seg_len_b = wi::abs (dr_b1->seg_len);

should work.

Richard.


> Thanks,
> bin
>>
>> 2017-05-22  Bin Cheng  <bin.cheng@arm.com>
>>
>>         * tree-data-ref.c (prune_runtime_alias_test_list): Relax minimal
>>         segment length for dr_b.
>>
>> gcc/testsuite/ChangeLog
>> 2017-05-22  Bin Cheng  <bin.cheng@arm.com>
>>
>>         * gcc.dg/vect/pr80815-3.c: New test.