> When downloading source code under the OpenHarmony_v1.x branches or tags, perform the operation procedure described in this section to install LLVM 9.0.0.
> When downloading source code under the OpenHarmony_v1.x branches or tags, perform the operation procedure described in this section to install LLVM 12.0.1.
>
> When downloading source code under the Master or non-OpenHarmony_v1.x branches or tags, skip this section. hb will automatically download the latest version of LLVM.