[Patch 8/17] Make _Float16 available if HFmode is available

gcc/

	* targhooks.c (default_floatn_mode): Enable _Float16 if a target
	provides HFmode.

From-SVN: r242778

gcc/ChangeLog

 2016-11-23  James Greenhalgh  <james.greenhalgh@arm.com>
 
+	* targhooks.c (default_floatn_mode): Enable _Float16 if a target
+	provides HFmode.
+
+2016-11-23  James Greenhalgh  <james.greenhalgh@arm.com>
+
 	* config/s390/s390.h (TARGET_FLT_EVAL_METHOD): Delete.
 	* config/m68k/m68k.h (TARGET_FLT_EVAL_METHOD): Delete.
 	* config/i386/i386.h (TARGET_FLT_EVAL_METHOD): Delete.

gcc/targhooks.c

@@ -514,10 +514,12 @@ default_floatn_mode (int n, bool extended)
       switch (n)
 	{
 	case 16:
-	  /* We do not use HFmode for _Float16 by default because the
-	     required excess precision support is not present and the
-	     interactions with promotion of the older __fp16 need to
-	     be worked out.  */
+	  /* Always enable _Float16 if we have basic support for the mode.
+	     Targets can control the range and precision of operations on
+	     the _Float16 type using TARGET_C_EXCESS_PRECISION.  */
+#ifdef HAVE_HFmode
+	  cand = HFmode;
+#endif
 	  break;
 
 	case 32: