[PATCH] Correct cost model for strided loads

[William J. Schmidt]

The fix for PR53331 caused a degradation to 187.facerec on
powerpc64-unknown-linux-gnu.  The following simple patch reverses the
degradation without otherwise affecting SPEC cpu2000 or cpu2006.
Bootstrapped and regtested on that platform with no new regressions.  Ok
for trunk?

Thanks,
Bill


2012-06-10  Bill Schmidt  <wschm...@linux.ibm.com>

        * tree-vect-stmts.c (vect_model_load_cost):  Change cost model
        for strided loads.


Index: gcc/tree-vect-stmts.c
===================================================================
--- gcc/tree-vect-stmts.c       (revision 188341)
+++ gcc/tree-vect-stmts.c       (working copy)
@@ -1031,11 +1031,10 @@ vect_model_load_cost (stmt_vec_info stmt_info, int
   /* The loads themselves.  */
   if (STMT_VINFO_STRIDE_LOAD_P (stmt_info))
     {
-      /* N scalar loads plus gathering them into a vector.
-         ???  scalar_to_vec isn't the cost for that.  */
+      /* N scalar loads plus gathering them into a vector.  */
       inside_cost += (vect_get_stmt_cost (scalar_load) * ncopies
                      * TYPE_VECTOR_SUBPARTS (STMT_VINFO_VECTYPE (stmt_info)));
-      inside_cost += ncopies * vect_get_stmt_cost (scalar_to_vec);
+      inside_cost += ncopies * vect_get_stmt_cost (vec_perm);
     }
   else
     vect_get_load_cost (first_dr, ncopies,