This adds code to the backend rtx_costs function in order to model the
costs of a load/store on condition.
Bootstrapped and regression tested on s390x.
gcc/ChangeLog:
2017-07-12 Andreas Krebbel <kreb...@linux.vnet.ibm.com>
* config/s390/s390.c (s390_rtx_costs): Return proper costs for
load/store on condition.
---
gcc/ChangeLog | 5 +++++
gcc/config/s390/s390.c | 42 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 47 insertions(+)
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e3d096c..128fc92 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2017-07-12 Andreas Krebbel <kreb...@linux.vnet.ibm.com>
+
+ * config/s390/s390.c (s390_rtx_costs): Return proper costs for
+ load/store on condition.
+
2017-07-11 Michael Collison <michael.colli...@arm.com>
* config/aarch64/aarch64-simd.md (aarch64_sub<mode>_compare0):
diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c
index 958ee3b..31ced21 100644
--- a/gcc/config/s390/s390.c
+++ b/gcc/config/s390/s390.c
@@ -3414,6 +3414,48 @@ s390_rtx_costs (rtx x, machine_mode mode, int outer_code,
*total = 0;
return true;
+ case SET:
+ {
+ /* Without this a conditional move instruction would be
+ accounted as 3 * COSTS_N_INSNS (set, if_then_else,
+ comparison operator). That's a bit pessimistic. */
+
+ if (!TARGET_Z196 || GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
+ return false;
+
+ rtx cond = XEXP (SET_SRC (x), 0);
+
+ if (!CC_REG_P (XEXP (cond, 0)) || !CONST_INT_P (XEXP (cond, 1)))
+ return false;
+
+ /* It is going to be a load/store on condition. Make it
+ slightly more expensive than a normal load. */
+ *total = COSTS_N_INSNS (1) + 1;
+
+ rtx dst = SET_DEST (x);
+ rtx then = XEXP (SET_SRC (x), 1);
+ rtx els = XEXP (SET_SRC (x), 2);
+
+ /* It is a real IF-THEN-ELSE. An additional move will be
+ needed to implement that. */
+ if (reload_completed
+ && !rtx_equal_p (dst, then)
+ && !rtx_equal_p (dst, els))
+ *total += COSTS_N_INSNS (1) / 2;
+
+ /* A minor penalty for constants we cannot directly handle. */
+ if ((CONST_INT_P (then) || CONST_INT_P (els))
+ && (!TARGET_Z13 || MEM_P (dst)
+ || (CONST_INT_P (then) && !satisfies_constraint_K (then))
+ || (CONST_INT_P (els) && !satisfies_constraint_K (els))))
+ *total += COSTS_N_INSNS (1) / 2;
+
+ /* A store on condition can only handle register src operands. */
+ if (MEM_P (dst) && (!REG_P (then) || !REG_P (els)))
+ *total += COSTS_N_INSNS (1) / 2;
+
+ return true;
+ }
case IOR:
/* risbg */
if (GET_CODE (XEXP (x, 0)) == AND
--
2.9.1
