https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94175
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jason Merrill <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:94e2418780f1d13235f3e2e6e5c09dbe821c1ce3 commit r10-7284-g94e2418780f1d13235f3e2e6e5c09dbe821c1ce3 Author: Jason Merrill <ja...@redhat.com> Date: Thu Mar 19 11:06:52 2020 -0400 c++: Avoid unnecessary empty class copy [94175]. A simple empty class copy is still simple when wrapped in a TARGET_EXPR, so we need to strip that as well. This change also exposed some unnecessary copies in return statements, which when returning by invisible reference led to <RETURN_EXPR <MEM_REF <RESULT_DECL>>>, which gimplify_return_expr didn't like. So we also need to strip the _REF when we eliminate the INIT_EXPR. gcc/cp/ChangeLog 2020-03-19 Jason Merrill <ja...@redhat.com> PR c++/94175 * cp-gimplify.c (simple_empty_class_p): Look through SIMPLE_TARGET_EXPR_P. (cp_gimplify_expr) [MODIFY_EXPR]: Likewise. [RETURN_EXPR]: Avoid producing 'return *retval;'. * call.c (build_call_a): Strip TARGET_EXPR from empty class arg. * cp-tree.h (SIMPLE_TARGET_EXPR_P): Check that TARGET_EXPR_INITIAL is non-null.
