fix for PR31617

From-SVN: r124109

gcc/ChangeLog

+2007-04-24  Richard Guenther  <rguenther@suse.de>
+	    Olga Golovanevsky  <olga@il.ibm.com>
+
+	* fold-const.c (multiple_of_p): Check for bottom 
+	to be zero. 
+
 2007-04-24  Richard Henderson  <rth@redhat.com>
 
 	* libgcc2.h (AVOID_FP_TYPE_CONVERSION): Rename from 

gcc/fold-const.c

@@ -13216,6 +13216,7 @@ multiple_of_p (tree type, tree top, tree bottom)
 
     case INTEGER_CST:
       if (TREE_CODE (bottom) != INTEGER_CST
+	  || integer_zerop (bottom)
 	  || (TYPE_UNSIGNED (type)
 	      && (tree_int_cst_sgn (top) < 0
 		  || tree_int_cst_sgn (bottom) < 0)))

gcc/testsuite/ChangeLog

+2007-04-24  Andrew Pinski  <andrew_pinski@playstation.sony.com>
+	    Olga Golovanevsky  <olga@il.ibm.com>
+
+	* g++.dg/other/str_empty.C: New test.
+	
 2007-04-24  Richard Henderson  <rth@redhat.com>
 
 	* gcc.dg/vect/vect.exp: Don't run tests on Alpha.