Other jumps are expressed by either GOTO_EXPR or RETURN_EXPR.
The operand of a GOTO_EXPR must be either a label or a variable
containing the address to jump to.
The operand of a RETURN_EXPR is either NULL_TREE or a
MODIFY_EXPR which sets the return value. It would be nice to
move the MODIFY_EXPR into a separate statement, but the special
return semantics in expand_return make that difficult. It may
still happen in the future, perhaps by moving most of that logic into
expand_assignment.