genrecog: Fix crash on invalid input

If your machine description refers to a non-existent predicate genrecog
crashes.  This fixes it.


	* genrecog.c (match_pattern_2): If pred is NULL don't call
	safe_predicate_mode on it.

From-SVN: r234206

gcc/ChangeLog

+2016-03-15  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	* genrecog.c (match_pattern_2): If pred is NULL don't call
+	safe_predicate_mode on it.
+
 2016-03-14  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/70219

gcc/genrecog.c

@@ -4037,7 +4037,7 @@ match_pattern_2 (state *s, md_rtx_info *info, position *pos, rtx pattern)
 		/* Check the mode first, to distinguish things like SImode
 		   and DImode register_operands, as described above.  */
 		machine_mode mode = GET_MODE (e->pattern);
-		if (safe_predicate_mode (pred, mode))
+		if (pred && safe_predicate_mode (pred, mode))
 		  s = add_decision (s, rtx_test::mode (e->pos), mode, true);
 
 		/* Assign to operands[] first, so that the rtx usually doesn't