PR tree-optimization/68835
	* tree.c (get_int_cst_ext_nunits): Return
	cst.get_precision () / HOST_BITS_PER_WIDE_INT + 1
	for all unsigned wi::neg_p (cst) constants.
	(build_new_int_cst): If cst.get_precision is not a multiple
	of HOST_BITS_PER_WIDE_INT, zero extend -1 to the precision
	% HOST_BITS_PER_WIDE_INT.

	* gcc.dg/pr68835-1.c: New test.
	* gcc.dg/pr68835-2.c: New test.

From-SVN: r231757