Method gen_return

mypyc/irbuild/nonlocalcontrol.py:92–132

(self, builder: IRBuilder, value: Value, line: int)

    """Default nonlocal control in a generator function outside statements."""

    def gen_return(self, builder: IRBuilder, value: Value, line: int) -> None:
        # Assign an invalid next label number so that the next time
        # __next__ is called, we jump to the case in which
        # StopIteration is raised.
        builder.assign(builder.fn_info.generator_class.next_label_target, Integer(-1), line)

        # Raise a StopIteration containing a field for the value that
        # should be returned. Before doing so, create a new block
        # without an error handler set so that the implicitly thrown
        # StopIteration isn't caught by except blocks inside of the
        # generator function.
        builder.builder.push_error_handler(None)
        builder.goto_and_activate(BasicBlock())

        # Skip creating a traceback frame when we raise here, because
        # we don't care about the traceback frame and it is kind of
        # expensive since raising StopIteration is an extremely common
        # case.  Also we call a special internal function to set
        # StopIteration instead of using RaiseStandardError because
        # the obvious thing doesn't work if the value is a tuple
        # (???).

        true, false = BasicBlock(), BasicBlock()
        stop_iter_reg = builder.fn_info.generator_class.stop_iter_value_reg
        assert stop_iter_reg is not None

        builder.add(Branch(stop_iter_reg, true, false, Branch.IS_ERROR))

        builder.activate_block(true)
        # The default/slow path is to raise a StopIteration exception with
        # return value.
        builder.call_c(set_stop_iteration_value, [value], NO_TRACEBACK_LINE_NO)
        builder.add(Unreachable())
        builder.builder.pop_error_handler()

        builder.activate_block(false)
        # The fast path is to store return value via caller-provided pointer
        # instead of raising an exception. This can only be used when the
        # caller is a native function.
        builder.add(SetMem(object_rprimitive, stop_iter_reg, value))
        builder.add(Return(Integer(0, object_rprimitive)))


class CleanupNonlocalControl(NonlocalControl):