[PATCH] Fix PR50969

["William J. Schmidt" <wschmidt at linux dot vnet dot ibm dot com>]

This fixes http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50969 by slightly
raising the cost of vector permutes on powerpc64 VSX targets (and
ensuring those costs are correctly used).  This reverses the performance
loss for 168.wupwise, and gives a slight boost to 433.milc as well.

In the long run, we will want to model VSX permutes differently, since
the real issue is that only one floating-point pipe can hold a permute
at a time.  Thus the present patch can be overly conservative when
permutes are rare compared with other vector instructions.

Bootstrapped and regtested on powerpc64-linux-gnu with no failures.  OK
for trunk?

Thanks,
Bill


2012-02-03  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR tree-optimization/50969
	* tree-vect-stmts.c (vect_model_store_cost): Correct statement cost to
	use vec_perm rather than vector_stmt.
	(vect_model_load_cost): Likewise.
	* config/rs6000/rs6000.c (rs6000_builtin_vectorization_cost): Revise
	cost of vec_perm for TARGET_VSX.


Index: gcc/tree-vect-stmts.c
===================================================================
--- gcc/tree-vect-stmts.c	(revision 183871)
+++ gcc/tree-vect-stmts.c	(working copy)
@@ -882,7 +882,7 @@ vect_model_store_cost (stmt_vec_info stmt_info, in
     {
       /* Uses a high and low interleave operation for each needed permute.  */
       inside_cost = ncopies * exact_log2(group_size) * group_size
-        * vect_get_stmt_cost (vector_stmt);
+        * vect_get_stmt_cost (vec_perm);
 
       if (vect_print_dump_info (REPORT_COST))
         fprintf (vect_dump, "vect_model_store_cost: strided group_size = %d .",
@@ -988,7 +988,7 @@ vect_model_load_cost (stmt_vec_info stmt_info, int
     {
       /* Uses an even and odd extract operations for each needed permute.  */
       inside_cost = ncopies * exact_log2(group_size) * group_size
-	* vect_get_stmt_cost (vector_stmt);
+	* vect_get_stmt_cost (vec_perm);
 
       if (vect_print_dump_info (REPORT_COST))
         fprintf (vect_dump, "vect_model_load_cost: strided group_size = %d .",
Index: gcc/config/rs6000/rs6000.c
===================================================================
--- gcc/config/rs6000/rs6000.c	(revision 183871)
+++ gcc/config/rs6000/rs6000.c	(working copy)
@@ -3540,9 +3540,13 @@ rs6000_builtin_vectorization_cost (enum vect_cost_
       case vec_to_scalar:
       case scalar_to_vec:
       case cond_branch_not_taken:
-      case vec_perm:
         return 1;
 
+      case vec_perm:
+	if (!TARGET_VSX)
+	  return 1;
+	return 2;
+
       case cond_branch_taken:
         return 3;