rs6000-string.c (expand_block_clear): Don't use unaligned vsx for 16B memset.

2018-06-26  Aaron Sawdey  <acsawdey@linux.ibm.com>

	* config/rs6000/rs6000-string.c (expand_block_clear): Don't use
	unaligned vsx for 16B memset.

From-SVN: r262158

gcc/ChangeLog

+2018-06-26  Aaron Sawdey  <acsawdey@linux.ibm.com>
+
+	* config/rs6000/rs6000-string.c (expand_block_clear): Don't use
+	unaligned vsx for 16B memset.
+
 2018-06-26  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	PR target/86285

gcc/config/rs6000/rs6000-string.c

@@ -90,7 +90,9 @@ expand_block_clear (rtx operands[])
       machine_mode mode = BLKmode;
       rtx dest;
 
-      if (bytes >= 16 && TARGET_ALTIVEC && (align >= 128 || TARGET_EFFICIENT_UNALIGNED_VSX))
+      if (TARGET_ALTIVEC
+	  && ((bytes >= 16 && align >= 128)
+	      || (bytes >= 32 && TARGET_EFFICIENT_UNALIGNED_VSX)))
 	{
 	  clear_bytes = 16;
 	  mode = V4SImode;