fix scalar BB vectorization costing

We were costing the scalar pattern stmts rather than the scalar
original stmt and also not appropriately looking at the pattern
stmt for whether the stmt is vectorized.

2020-07-03  Richard Biener  <rguenther@suse.de>

	* tree-vect-slp.c (vect_bb_slp_scalar_cost): Cost the
	original non-pattern stmts, look at the pattern stmt
	vectorization status.

	* gcc.dg/vect/costmodel/x86_64/costmodel-vect-slp-2.c: New
	testcase.

2 files changed, 28 insertions, 12 deletions

diff --git a/gcc/testsuite/gcc.dg/vect/costmodel/x86_64/costmodel-vect-slp-2.c b/gcc/testsuite/gcc.dg/vect/costmodel/x86_64/costmodel-vect-slp-2.c
new file mode 100644
index 0000000..1b7ac34
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/costmodel/x86_64/costmodel-vect-slp-2.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-fdump-tree-slp-details" } */
+
+int a[4], b[4];
+void foo()
+{
+  a[0] = b[0] / 7;
+  a[1] = b[1] / 7;
+  a[2] = b[2] / 7;
+  a[3] = b[3] / 7;
+}
+
+/* We should cost the original division stmt, not the scalar pattern stmts.  */
+/* { dg-final { scan-tree-dump-times " / 7 1 times scalar_stmt costs" 4 "slp2" } } */
diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
index 727eba0..33fc87a 100644
--- a/gcc/tree-vect-slp.c
+++ b/gcc/tree-vect-slp.c
@@ -3039,7 +3039,6 @@ vect_bb_slp_scalar_cost (vec_info *vinfo,
 
   FOR_EACH_VEC_ELT (SLP_TREE_SCALAR_STMTS (node), i, stmt_info)
     {
-      gimple *stmt = stmt_info->stmt;
       ssa_op_iter op_iter;
       def_operand_p def_p;
 
@@ -3051,7 +3050,9 @@ vect_bb_slp_scalar_cost (vec_info *vinfo,
 	 required defs in the SLP children in the scalar cost.  This
 	 way we make the vectorization more costly when compared to
 	 the scalar cost.  */
-      FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, op_iter, SSA_OP_DEF)
+      stmt_vec_info orig_stmt_info = vect_orig_stmt (stmt_info);
+      gimple *orig_stmt = orig_stmt_info->stmt;
+      FOR_EACH_SSA_DEF_OPERAND (def_p, orig_stmt, op_iter, SSA_OP_DEF)
 	{
 	  imm_use_iterator use_iter;
 	  gimple *use_stmt;
@@ -3059,7 +3060,8 @@ vect_bb_slp_scalar_cost (vec_info *vinfo,
 	    if (!is_gimple_debug (use_stmt))
 	      {
 		stmt_vec_info use_stmt_info = vinfo->lookup_stmt (use_stmt);
-		if (!use_stmt_info || !PURE_SLP_STMT (use_stmt_info))
+		if (!use_stmt_info
+		    || !PURE_SLP_STMT (vect_stmt_to_vectorize (use_stmt_info)))
 		  {
 		    (*life)[i] = true;
 		    BREAK_FROM_IMM_USE_STMT (use_iter);
@@ -3070,23 +3072,23 @@ vect_bb_slp_scalar_cost (vec_info *vinfo,
 	continue;
 
       /* Count scalar stmts only once.  */
-      if (gimple_visited_p (stmt))
+      if (gimple_visited_p (orig_stmt))
 	continue;
-      gimple_set_visited (stmt, true);
+      gimple_set_visited (orig_stmt, true);
 
       vect_cost_for_stmt kind;
-      if (STMT_VINFO_DATA_REF (stmt_info))
-        {
-          if (DR_IS_READ (STMT_VINFO_DATA_REF (stmt_info)))
+      if (STMT_VINFO_DATA_REF (orig_stmt_info))
+	{
+	  if (DR_IS_READ (STMT_VINFO_DATA_REF (orig_stmt_info)))
 	    kind = scalar_load;
-          else
+	  else
 	    kind = scalar_store;
-        }
-      else if (vect_nop_conversion_p (stmt_info))
+	}
+      else if (vect_nop_conversion_p (orig_stmt_info))
 	continue;
       else
 	kind = scalar_stmt;
-      record_stmt_cost (cost_vec, 1, kind, stmt_info, 0, vect_body);
+      record_stmt_cost (cost_vec, 1, kind, orig_stmt_info, 0, vect_body);
     }
 
   auto_vec<bool, 20> subtree_life;