Re: [PATCH 1/2] vect: Refactor code for index == count in vect_transform_slp_perm_load_1

["Kewen.Lin" <linkw@linux.ibm.com>]

Hi Richi,

on 2023/5/17 14:34, Richard Biener wrote:
> On Wed, May 17, 2023 at 8:09 AM Kewen.Lin <linkw@linux.ibm.com> wrote:
>>
>> Hi,
>>
>> This patch is to refactor the handlings for the case (index
>> == count) in a loop of vect_transform_slp_perm_load_1, in
>> order to prepare a subsequent adjustment on *nperm.  This
>> patch doesn't have any functional changes.
> 
> The diff is impossible to be reviewed - can you explain the
> refactoring you have done or also attach a patch more clearly
> showing what you change?

Sorry, I should have made it more clear.
It mainly to combine these two hunks:
  
  if (index == count && !noop_p)
    {  
       // A ...
       // ++*n_perms;
    }

  if (index == count)
    {
       if (!analyze_only)
         {
            if (!noop_p)
               // B1 ...
            
            // B2 ...
           
            for ...
              {
                 if (!noop_p)
                    // B3 building VEC_PERM_EXPR
                 else
                    // B4 building nothing (no uses for B2 and its seq)
              }
         }
       // B5
    }

The former can be part of the latter, so it becomes to:

  if (index == count)
    {
       if (!noop_p)
         {
           // A ...
           // ++*n_perms;

           if (!analyze_only)
             {
                // B1 ...
                // B2 ...
                for ...
                   // B3 building VEC_PERM_EXPR
             }
         }
       else if (!analyze_only)
         {
            // no B2 since no any further uses here.
            for ...
              // B4 building nothing
         }
        // B5 ...
    }

But it's mainly the basic for the subsequent patch for consistent n_perms calculation,
the patch 2/2 is to make it further become to:

  if (index == count)
    {
       if (!noop_p)
         {
           // A ...

           if (!analyze_only)
             // B1 ...
           
           // B2 ... (trivial computations during analyze_only or not)

           for ...
             {
                // ++*n_perms;  (now n_perms is consistent with building VEC_PERM_EXPR)
                if (analyze_only)
                   continue;
                // B3 building VEC_PERM_EXPR
             }
         }
       else if (!analyze_only)
         {
            // no B2 since no any further uses here.
            for ...
              // B4 building nothing
         }
        // B5 ...
    }

BR,
Kewen


> 
>> Bootstrapped and regtested on x86_64-redhat-linux,
>> aarch64-linux-gnu and powerpc64{,le}-linux-gnu.
>>
>> BR,
>> Kewen
>> -----
>> gcc/ChangeLog:
>>
>>         * tree-vect-slp.cc (vect_transform_slp_perm_load_1): Refactor the
>>         handling on the case index == count.
>> ---
>>  gcc/tree-vect-slp.cc | 89 ++++++++++++++++++++++----------------------
>>  1 file changed, 44 insertions(+), 45 deletions(-)
>>
>> diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
>> index 3b7a21724ec..e5c9d7e766e 100644
>> --- a/gcc/tree-vect-slp.cc
>> +++ b/gcc/tree-vect-slp.cc
>> @@ -8230,59 +8230,50 @@ vect_transform_slp_perm_load_1 (vec_info *vinfo, slp_tree node,
>>         noop_p = false;
>>        mask[index++] = mask_element;
>>
>> -      if (index == count && !noop_p)
>> +      if (index == count)
>>         {
>> -         indices.new_vector (mask, second_vec_index == -1 ? 1 : 2, nunits);
>> -         if (!can_vec_perm_const_p (mode, mode, indices))
>> +         if (!noop_p)
>>             {
>> -             if (dump_p)
>> +             indices.new_vector (mask, second_vec_index == -1 ? 1 : 2, nunits);
>> +             if (!can_vec_perm_const_p (mode, mode, indices))
>>                 {
>> -                 dump_printf_loc (MSG_MISSED_OPTIMIZATION,
>> -                                  vect_location,
>> -                                  "unsupported vect permute { ");
>> -                 for (i = 0; i < count; ++i)
>> +                 if (dump_p)
>>                     {
>> -                     dump_dec (MSG_MISSED_OPTIMIZATION, mask[i]);
>> -                     dump_printf (MSG_MISSED_OPTIMIZATION, " ");
>> +                     dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
>> +                                      "unsupported vect permute { ");
>> +                     for (i = 0; i < count; ++i)
>> +                       {
>> +                         dump_dec (MSG_MISSED_OPTIMIZATION, mask[i]);
>> +                         dump_printf (MSG_MISSED_OPTIMIZATION, " ");
>> +                       }
>> +                     dump_printf (MSG_MISSED_OPTIMIZATION, "}\n");
>>                     }
>> -                 dump_printf (MSG_MISSED_OPTIMIZATION, "}\n");
>> +                 gcc_assert (analyze_only);
>> +                 return false;
>>                 }
>> -             gcc_assert (analyze_only);
>> -             return false;
>> -           }
>>
>> -         ++*n_perms;
>> -       }
>> +             ++*n_perms;
>>
>> -      if (index == count)
>> -       {
>> -         if (!analyze_only)
>> -           {
>> -             tree mask_vec = NULL_TREE;
>> -
>> -             if (! noop_p)
>> -               mask_vec = vect_gen_perm_mask_checked (vectype, indices);
>> +             if (!analyze_only)
>> +               {
>> +                 tree mask_vec = vect_gen_perm_mask_checked (vectype, indices);
>>
>> -             if (second_vec_index == -1)
>> -               second_vec_index = first_vec_index;
>> +                 if (second_vec_index == -1)
>> +                   second_vec_index = first_vec_index;
>>
>> -             for (unsigned int ri = 0; ri < nvectors_per_build; ++ri)
>> -               {
>> -                 /* Generate the permute statement if necessary.  */
>> -                 tree first_vec = dr_chain[first_vec_index + ri];
>> -                 tree second_vec = dr_chain[second_vec_index + ri];
>> -                 gimple *perm_stmt;
>> -                 if (! noop_p)
>> +                 for (unsigned int ri = 0; ri < nvectors_per_build; ++ri)
>>                     {
>> -                     gassign *stmt = as_a <gassign *> (stmt_info->stmt);
>> +                     /* Generate the permute statement if necessary.  */
>> +                     tree first_vec = dr_chain[first_vec_index + ri];
>> +                     tree second_vec = dr_chain[second_vec_index + ri];
>> +                     gassign *stmt = as_a<gassign *> (stmt_info->stmt);
>>                       tree perm_dest
>>                         = vect_create_destination_var (gimple_assign_lhs (stmt),
>>                                                        vectype);
>>                       perm_dest = make_ssa_name (perm_dest);
>> -                     perm_stmt
>> +                     gimple *perm_stmt
>>                         = gimple_build_assign (perm_dest, VEC_PERM_EXPR,
>> -                                              first_vec, second_vec,
>> -                                              mask_vec);
>> +                                              first_vec, second_vec, mask_vec);
>>                       vect_finish_stmt_generation (vinfo, stmt_info, perm_stmt,
>>                                                    gsi);
>>                       if (dce_chain)
>> @@ -8290,15 +8281,23 @@ vect_transform_slp_perm_load_1 (vec_info *vinfo, slp_tree node,
>>                           bitmap_set_bit (used_defs, first_vec_index + ri);
>>                           bitmap_set_bit (used_defs, second_vec_index + ri);
>>                         }
>> +
>> +                     /* Store the vector statement in NODE.  */
>> +                     SLP_TREE_VEC_STMTS (node) [vect_stmts_counter++]
>> +                       = perm_stmt;
>>                     }
>> -                 else
>> -                   {
>> -                     /* If mask was NULL_TREE generate the requested
>> -                        identity transform.  */
>> -                     perm_stmt = SSA_NAME_DEF_STMT (first_vec);
>> -                     if (dce_chain)
>> -                       bitmap_set_bit (used_defs, first_vec_index + ri);
>> -                   }
>> +               }
>> +           }
>> +         else if (!analyze_only)
>> +           {
>> +             for (unsigned int ri = 0; ri < nvectors_per_build; ++ri)
>> +               {
>> +                 tree first_vec = dr_chain[first_vec_index + ri];
>> +                 /* If mask was NULL_TREE generate the requested
>> +                    identity transform.  */
>> +                 gimple *perm_stmt = SSA_NAME_DEF_STMT (first_vec);
>> +                 if (dce_chain)
>> +                   bitmap_set_bit (used_defs, first_vec_index + ri);
>>
>>                   /* Store the vector statement in NODE.  */
>>                   SLP_TREE_VEC_STMTS (node)[vect_stmts_counter++] = perm_stmt;
>> --
>> 2.39.1