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 <wschm...@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;
