Index: fold-const.c
===================================================================
--- fold-const.c	(revision 271694)
+++ fold-const.c	(working copy)
@@ -6475,8 +6475,13 @@ extract_muldiv_1 (tree t, tree c, enum t
 	 apply the distributive law to commute the multiply and addition
 	 if the multiplication of the constants doesn't overflow
 	 and overflow is defined.  With undefined overflow
-	 op0 * c might overflow, while (op0 + orig_op1) * c doesn't.  */
-      if (code == MULT_EXPR && TYPE_OVERFLOW_WRAPS (ctype))
+	 op0 * c might overflow, while (op0 + orig_op1) * c doesn't.
+	 But fold_plusminus_mult_expr would factor back any power-of-two
+	 value so do not distribute in the first place in this case.  */
+      if (code == MULT_EXPR
+	  && TYPE_OVERFLOW_WRAPS (ctype)
+	  && !(tree_fits_shwi_p (c)
+	       && exact_log2 (absu_hwi (tree_to_shwi (c))) > 0))
 	return fold_build2 (tcode, ctype,
 			    fold_build2 (code, ctype,
 					 fold_convert (ctype, op0),