One-line tidy of bit-twiddle expression in aarch64.c

	* config/aarch64/aarch64.c (aarch64_expand_vec_perm_1): Tidy bit-flip
	expression.

From-SVN: r210005

gcc/ChangeLog

+2014-05-02  Alan Lawrence  <alan.lawrence@arm.com>
+
+	* config/aarch64/aarch64.c (aarch64_expand_vec_perm_1): Tidy bit-flip
+	expression.
+
 2014-05-02  Marek Polacek  <polacek@redhat.com>
 
 	* doc/invoke.texi: Describe -fsanitize=float-divide-by-zero.

gcc/config/aarch64/aarch64.c

@@ -8180,8 +8180,9 @@ aarch64_expand_vec_perm_const_1 (struct expand_vec_perm_d *d)
       unsigned i, nelt = d->nelt;
       rtx x;
 
+      gcc_assert (nelt == (nelt & -nelt));
       for (i = 0; i < nelt; ++i)
-	d->perm[i] = (d->perm[i] + nelt) & (2 * nelt - 1);
+	d->perm[i] ^= nelt; /* Keep the same index, but in the other vector.  */
 
       x = d->op0;
       d->op0 = d->op1;