rs6000: Add command line and builtin compatibility check

2020-03-20  Carl Love  <cel@us.ibm.com>

	PR/target 87583
	* gcc/config/rs6000/rs6000.c (rs6000_option_override_internal):
	Add check for TARGET_FPRND for Power 7 or newer.

gcc/ChangeLog

+2020-03-20  Carl Love  <cel@us.ibm.com>
+
+	PR/target 87583
+	* gcc/config/rs6000/rs6000.c (rs6000_option_override_internal):
+	Add check for TARGET_FPRND for Power 7 or newer.
+
 2020-03-20  Jan Hubicka  <hubicka@ucw.cz>
 
 	PR ipa/93347

gcc/config/rs6000/rs6000.c

@@ -3714,6 +3714,14 @@ rs6000_option_override_internal (bool global_init_p)
       rs6000_isa_flags &= ~OPTION_MASK_CRYPTO;
     }
 
+  if (!TARGET_FPRND && TARGET_VSX)
+    {
+      if (rs6000_isa_flags_explicit & OPTION_MASK_FPRND)
+	/* TARGET_VSX = 1 implies Power 7 and newer */
+	error ("%qs requires %qs", "-mvsx", "-mfprnd");
+      rs6000_isa_flags &= ~OPTION_MASK_FPRND;
+    }
+
   if (TARGET_DIRECT_MOVE && !TARGET_VSX)
     {
       if (rs6000_isa_flags_explicit & OPTION_MASK_DIRECT_MOVE)