combine.c (simplify_shift_const): Bound shift count when combining shifts.

        * combine.c (simplify_shift_const): Bound shift count when
        combining shifts.

From-SVN: r35739

gcc/ChangeLog

+2000-08-15  Richard Henderson  <rth@cygnus.com>
+
+	* combine.c (simplify_shift_const): Bound shift count when
+	combining shifts.
+
 Tue Aug 15 17:33:05 2000  Richard Kenner  <kenner@vlsi1.ultra.nyu.edu>
 
 	* calls.c (ECF_SP_DEPRESSED): New macro.

gcc/combine.c

@@ -9149,6 +9149,8 @@ simplify_shift_const (x, code, result_mode, varop, input_count)
 		    break;
 
 		  count += first_count;
+		  if (count >= GET_MODE_BITSIZE (shift_mode))
+		    count = GET_MODE_BITSIZE (shift_mode) - 1;
 		  varop = XEXP (varop, 0);
 		  continue;
 		}
@@ -9202,6 +9204,9 @@ simplify_shift_const (x, code, result_mode, varop, input_count)
 	      else
 		count = signed_count;
 
+	      if (count >= GET_MODE_BITSIZE (shift_mode))
+		count = GET_MODE_BITSIZE (shift_mode) - 1;
+
 	      varop = XEXP (varop, 0);
 	      continue;
 	    }