rs6000.md (movsi_from_df): Optimize converting a DFmode to a SFmode...

2017-09-26  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* config/rs6000/rs6000.md (movsi_from_df): Optimize converting a
	DFmode to a SFmode, and then needing to move the SFmode to a GPR
	to use the XSCVDPSP instruction instead of FRSP and XSCVDPSPN.

From-SVN: r253210

gcc/ChangeLog

@@ -11,7 +11,9 @@
 	(movdi_from_sf_zero_ext): Likewise.
 	(reload_gpr_from_vsxsf): Likewise.
 	(p8_mfvsrd_4_disf): Delete, no longer used.
-
+	(movsi_from_df): Optimize converting a DFmode to a SFmode, and
+	then needing to move the SFmode to a GPR to use the XSCVDPSP
+	instruction instead of FRSP and XSCVDPSPN.
 
 2017-09-26  Martin Jambor  <mjambor@suse.cz>
 

gcc/config/rs6000/rs6000.md

@@ -6919,6 +6919,26 @@
 		"4,          4,           4,           4,        8,
 		 8,          4")])
 
+;; Like movsi_from_sf, but combine a convert from DFmode to SFmode before
+;; moving it to SImode.  We can do a SFmode store without having to do the
+;; conversion explicitly.  If we are doing a register->register conversion, use
+;; XSCVDPSP instead of XSCVDPSPN, since the former handles cases where the
+;; input will not fit in a SFmode, and the later assumes the value has already
+;; been rounded.
+(define_insn "*movsi_from_df"
+  [(set (match_operand:SI 0 "nonimmediate_operand"         "=wa,m,wY,Z")
+	(unspec:SI [(float_truncate:SF
+		     (match_operand:DF 1 "gpc_reg_operand" "wa, f,wb,wa"))]
+		    UNSPEC_SI_FROM_SF))]
+
+  "TARGET_NO_SF_SUBREG"
+  "@
+   xscvdpsp %x0,%x1
+   stfs%U0%X0 %1,%0
+   stxssp %1,%0
+   stxsspx %x1,%y0"
+  [(set_attr "type"   "fp,fpstore,fpstore,fpstore")])
+
 ;; Split a load of a large constant into the appropriate two-insn
 ;; sequence.