Currently, we can't use `add_load_index()` or `add_load_component()` on the loads to the `"retval"` variables that come from `add_call()` because these functions assume that the loaded value (`var_instr`) won't change between its location and the location and the new load to be created.
We can't get rid of this assumptions either, because, at least `add_load_index()` may be used in the lhs of an assignment, and in that case we can't store to the "deref" synthetic: ``` x[0] = 20; ```
Here I implemented the alternative solution of copying `"retval"` into a synthetic variable after each function call, but we may want to discuss this approach.
-- v2: https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/93