Function ggml_opt_prepare_alloc 

pub unsafe extern "C" fn ggml_opt_prepare_alloc(
    opt_ctx: ggml_opt_context_t,
    ctx_compute: *mut ggml_context,
    gf: *mut ggml_cgraph,
    inputs: *mut ggml_tensor,
    outputs: *mut ggml_tensor,
)