Re: [PATCH 1/2] Assign vertex weight to all nodes

Richard Biener <[email protected]> writes:
> SLP permute nodes (can) have no SLP_TREE_REPRESENTATIVE, avoid
> leaving vertex weight (later used for costing) at zero but
> assign weight based on the region entry block.

That's better than 0 :) but is there a plan to make the choice of
block more accurate in future?  Using the entry block for something
that actually ends up in a loop would defeat the speed-based costing.

Richard

>
> This avoids regressing bb-slp-layout-18.c and bb-slp-pr54400.c
> with 2/2 which drops SLP_TREE_REPRESENTATIVE from all permute
> nodes.
>
> 	* tree-vect-slp.cc (vect_slp_node_weight): Get vinfo as
> 	context.  For nodes without representative use the
> 	region entry block.
> 	(vect_optimize_slp_pass::start_choosing_layouts): Always
> 	assign vertex weight.
> ---
>  gcc/tree-vect-slp.cc | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
> index 5e729e478ce..b2f14e6528a 100644
> --- a/gcc/tree-vect-slp.cc
> +++ b/gcc/tree-vect-slp.cc
> @@ -346,10 +346,14 @@ vect_free_oprnd_info (vec<slp_oprnd_info> &oprnds_info)
>     a "more important" node when optimizing for speed).  */
>  
>  static sreal
> -vect_slp_node_weight (slp_tree node)
> +vect_slp_node_weight (vec_info *vinfo, slp_tree node)
>  {
> -  stmt_vec_info stmt_info = vect_orig_stmt (SLP_TREE_REPRESENTATIVE (node));
> -  basic_block bb = gimple_bb (stmt_info->stmt);
> +  stmt_vec_info stmt_info = SLP_TREE_REPRESENTATIVE (node);
> +  basic_block bb;
> +  if (!stmt_info)
> +    bb = vinfo->bbs[0];
> +  else
> +    bb = gimple_bb (vect_orig_stmt (stmt_info)->stmt);
>    return bb->count.to_sreal_scale (ENTRY_BLOCK_PTR_FOR_FN (cfun)->count);
>  }
>  
> @@ -7520,10 +7524,10 @@ vect_optimize_slp_pass::start_choosing_layouts ()
>        auto &partition = m_partitions[vertex.partition];
>        slp_tree node = vertex.node;
>  
> +      vertex.weight = vect_slp_node_weight (m_vinfo, node);
> +
>        if (stmt_vec_info rep = SLP_TREE_REPRESENTATIVE (node))
>  	{
> -	  vertex.weight = vect_slp_node_weight (node);
> -
>  	  /* We do not handle stores with a permutation, so all
>  	     incoming permutations must have been materialized.