[03/46] Remove unnecessary update of NUM_SLP_USES

[03/46] Remove unnecessary update of NUM_SLP_USES

vect_free_slp_tree had:

  gimple *stmt;
  FOR_EACH_VEC_ELT (SLP_TREE_SCALAR_STMTS (node), i, stmt)
    /* After transform some stmts are removed and thus their vinfo is gone.  */
    if (vinfo_for_stmt (stmt))
      {
	gcc_assert (STMT_VINFO_NUM_SLP_USES (vinfo_for_stmt (stmt)) > 0);
	STMT_VINFO_NUM_SLP_USES (vinfo_for_stmt (stmt))--;
      }

But after transform this update is redundant even for statements that do
exist, so it seems better to skip this loop for the final teardown.

2018-07-31  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* tree-vectorizer.h (vect_free_slp_instance): Add a final_p parameter.
	* tree-vect-slp.c (vect_free_slp_tree): Likewise.  Don't update
	STMT_VINFO_NUM_SLP_USES when it's true.
	(vect_free_slp_instance): Add a final_p parameter and pass it to
	vect_free_slp_tree.
	(vect_build_slp_tree_2): Update call to vect_free_slp_instance.
	(vect_analyze_slp_instance): Likewise.
	(vect_slp_analyze_operations): Likewise.
	(vect_slp_analyze_bb_1): Likewise.
	* tree-vectorizer.c (vec_info): Likewise.
	* tree-vect-loop.c (vect_transform_loop): Likewise.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@263118 138bc75d-0d04-0410-961f-82ee72b054a4