re PR rtl-optimization/45728 (ICE: in gen_lowpart_general, at rtlhooks.c:59 at -O1 when comparing union members)

	PR rtl-optimization/45728
	* expr.c (expand_expr_real_1): If op0 isn't REG or MEM, try
	gen_lowpart_common first and if that fails, force_reg first
	before calling gen_lowpart.

	* gcc.c-torture/compile/pr45728.c: New test.

From-SVN: r164456