[Committed] S/390: Increase register move costs for FPR->GPR moves
Andreas Krebbel
krebbel@linux.vnet.ibm.com
Tue Jan 27 16:30:00 GMT 2015
Hi,
I've committed the attached patch which fixes a 4.8 vs 4.9/5.0
performance regression introduced with the aggressive use of FPRs as
spill slots.
Committed to mainline and 4.9 branch.
Bye,
-Andreas-
2015-01-27 Andreas Krebbel <Andreas.Krebbel@de.ibm.com>
* config/s390/s390.c (s390_register_move_cost): Increase costs for
FPR->GPR moves.
diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c
index 36b547d..fcde638 100644
--- a/gcc/config/s390/s390.c
+++ b/gcc/config/s390/s390.c
@@ -2393,16 +2393,29 @@ s390_float_const_zero_p (rtx value)
/* Implement TARGET_REGISTER_MOVE_COST. */
static int
-s390_register_move_cost (machine_mode mode ATTRIBUTE_UNUSED,
+s390_register_move_cost (machine_mode mode,
reg_class_t from, reg_class_t to)
{
- /* On s390, copy between fprs and gprs is expensive as long as no
- ldgr/lgdr can be used. */
- if ((!TARGET_Z10 || GET_MODE_SIZE (mode) != 8)
- && ((reg_classes_intersect_p (from, GENERAL_REGS)
- && reg_classes_intersect_p (to, FP_REGS))
- || (reg_classes_intersect_p (from, FP_REGS)
- && reg_classes_intersect_p (to, GENERAL_REGS))))
+ /* On s390, copy between fprs and gprs is expensive. */
+
+ /* It becomes somewhat faster having ldgr/lgdr. */
+ if (TARGET_Z10 && GET_MODE_SIZE (mode) == 8)
+ {
+ /* ldgr is single cycle. */
+ if (reg_classes_intersect_p (from, GENERAL_REGS)
+ && reg_classes_intersect_p (to, FP_REGS))
+ return 1;
+ /* lgdr needs 3 cycles. */
+ if (reg_classes_intersect_p (to, GENERAL_REGS)
+ && reg_classes_intersect_p (from, FP_REGS))
+ return 3;
+ }
+
+ /* Otherwise copying is done via memory. */
+ if ((reg_classes_intersect_p (from, GENERAL_REGS)
+ && reg_classes_intersect_p (to, FP_REGS))
+ || (reg_classes_intersect_p (from, FP_REGS)
+ && reg_classes_intersect_p (to, GENERAL_REGS)))
return 10;
return 1;
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