[fixes ICE-on-CC0 regression from r180192 (PR middle-end/50780) that triggers
 during compilation of Ada's libraries with 68060 tuning; see PR49847 for
 another ICE-on-CC0 regression from r180192 <mikpe@it.uu.se>]

gcc/

2013-03-23  Mikael Pettersson  <mikpe@it.uu.se>

	PR ada/48835
	* cse.c (fold_rtx) <case CC0>: If prev_insn_cc0 is NULL
	return the orginal expression x.

--- gcc-4.8.0/gcc/cse.c.~1~	2013-02-07 09:07:04.000000000 +0100
+++ gcc-4.8.0/gcc/cse.c	2013-03-23 17:14:33.793056660 +0100
@@ -3137,6 +3137,8 @@ fold_rtx (rtx x, rtx insn)
 
 #ifdef HAVE_cc0
     case CC0:
+      if (! prev_insn_cc0)
+	return x;
       return prev_insn_cc0;
 #endif