fold-const.c (multiple_of_p): Handle BIT_AND_EXPR when BOTTOM is a power of two.

        * fold-const.c (multiple_of_p): Handle BIT_AND_EXPR when
        BOTTOM is a power of two.

From-SVN: r92358

gcc/ChangeLog

 2004-12-18  Richard Henderson  <rth@redhat.com>
 
+	* fold-const.c (multiple_of_p): Handle BIT_AND_EXPR when
+	BOTTOM is a power of two.
+
+2004-12-18  Richard Henderson  <rth@redhat.com>
+
 	* tree-nested.c (save_tmp_var): New.
 	(struct walk_stmt_info): Add is_lhs.
 	(walk_stmts) <MODIFY_EXPR>: Be more accurate with setting of

gcc/fold-const.c

@@ -9541,6 +9541,13 @@ multiple_of_p (tree type, tree top, tree bottom)
 
   switch (TREE_CODE (top))
     {
+    case BIT_AND_EXPR:
+      /* Bitwise and provides a power of two multiple.  If the mask is
+	 a multiple of BOTTOM then TOP is a multiple of BOTTOM.  */
+      if (!integer_pow2p (bottom))
+	return 0;
+      /* FALLTHRU */
+
     case MULT_EXPR:
       return (multiple_of_p (type, TREE_OPERAND (top, 0), bottom)
 	      || multiple_of_p (type, TREE_OPERAND (top, 1), bottom));