re PR tree-optimization/83609 (ICE in read_complex_part at gcc/expr.c:3202)

re PR tree-optimization/83609 (ICE in read_complex_part at gcc/expr.c:3202)

	PR middle-end/83609
	* expr.c (expand_assignment): Fix up a typo in simplify_gen_subreg
	last argument when extracting from CONCAT.  If either from_real or
	from_imag is NULL, use expansion through memory.  If result is not
	a CONCAT and simplify_gen_subreg fails, try to simplify_gen_subreg
	the parts directly to inner mode, if even that fails, use expansion
	through memory.

	* gcc.dg/pr83609.c: New test.
	* g++.dg/opt/pr83609.C: New test.

From-SVN: r256052