re PR target/84369 (test case gcc.dg/sms-10.c fails on power9)

	PR target/84369
	* config/rs6000/power9.md: Add store forwarding bypass.

From-SVN: r270394

gcc/ChangeLog

+2019-04-16  Pat Haugen  <pthaugen@us.ibm.com>
+
+	PR target/84369
+	* config/rs6000/power9.md: Add store forwarding bypass.
+
 2019-04-16  Alexandre Oliva <aoliva@redhat.com>
 
 	PR debug/89528

gcc/config/rs6000/power9.md

@@ -236,6 +236,9 @@
        (eq_attr "cpu" "power9"))
   "DU_super_power9,LSU_pair_power9")
 
+; Store forwarding latency is 6
+(define_bypass 6 "power9-*store*" "power9-*load*")
+
 (define_insn_reservation "power9-larx" 4
   (and (eq_attr "type" "load_l")
        (eq_attr "cpu" "power9"))