c++: coroutines and return in registers [PR118874]

c++: coroutines and return in registers [PR118874]

Because coroutines insert a call to the resumer between the initialization
of the return value and the actual return to the caller, we need to
duplicate the work of gimplify_return_expr for the !aggregate_value_p case.

	PR c++/117364
	PR c++/118874

gcc/cp/ChangeLog:

	* coroutines.cc (cp_coroutine_transform::build_ramp_function): For
	!aggregate_value_p return force return value into a local temp.

gcc/testsuite/ChangeLog:

	* g++.dg/coroutines/torture/pr118874.C: New test.

Co-authored-by: Jakub Jelinek <jakub@redhat.com>