re PR target/30243 ([avr] signbit() causes an internal compiler error)

PR target/30243
* builtins.c (expand_builtin_signbit): Don't take lowpart when register is already smaller or equal to required mode.

From-SVN: r136376

gcc/ChangeLog

+2008-06-04  Andy Hutchinson  <hutchinsonandy@aim.com>
+
+	PR target/30243
+	* builtins.c (expand_builtin_signbit): Don't take lowpart when
+	register is already smaller or equal to required mode. 
+
 2008-06-04  Xinliang David Li  <davidxl@google.com>
 
 	* tree-call-cdce.c: New file. 

gcc/builtins.c

@@ -5786,7 +5786,7 @@ expand_builtin_signbit (tree exp, rtx target)
 	  lo = 0;
 	}
 
-      if (imode != rmode)
+      if (GET_MODE_SIZE (imode) > GET_MODE_SIZE (rmode))
 	temp = gen_lowpart (rmode, temp);
       temp = expand_binop (rmode, and_optab, temp,
 			   immed_double_const (lo, hi, rmode),