I am sorry to add on like this, but if it was not mentioned, I am not
using any prebuilt repository AOSP bundled with llvm_android. This is
the reason why I spent the time emerging Clang on my phone; for using it
to build stage1.
Although if advised otherwise, I could potentially break the AOSP
development cycle for our use and start the same cycle but with prebuilt
LLVM toolchain for AArch64 host instead of X86. I could expand on how to
do this, if you would like.

On 20/07/25 01:33PM, Gunwant Jain wrote:
> On 20/07/25 11:00AM, Benda Xu wrote:
> > Gunwant Jain <therealgunwant@gmail.com> writes:
> > 
> > > Yes it did.
> > > I can also report that llvm_android's stage1 clang is compiled for
> > > aarch64, I am on the stage2 step currently.
> > 
> > Good.  Could you please remind me of the meanings of llvm stage1 and
> > stage2?
> 
> Sure. AOSP provides its own distribution of LLVM. So most of what stage1
> and stage2 I will be describing could be taken from [1]. 
> Basically, we build LLVM stage1 using our own host toolchain. Then we
> use the newly built stage1 compiler to build stage2, the ready to use
> toolchain.
> 
> Coming to how this goes in our use-case, if we were to build the LLVM
> toolchain using llvm_android (basically just build scripts), we will use
> a prebuilt Clang toolchain, bundled with llvm_android to build stage1. 
> Also AOSP targets only X86 architechture in stage1.
> After stage1 is built, the build script proceeds to start building
> stage2. This is where we use the newly built stage1 compilers to build
> stage2 compilers. AOSP targets AArch64, ARM, X86 and BPF when building
> stage2. Then the build script packages stage2 install and dumps the tar
> for our use.
> 
> In the cycle of AOSP development, this newly packaged stage2 will be
> provided as the prebuilt LLVM toolchain in [2]. This repository is used:
>     - In the AOSP tree, when someone builds a new custom ROM.
>     - In llvm_android as the prebuilt toolchain used to build a version
>       bumped stage1.
> 
> For us, we will have to target AArch64 in building both stage1 and
> stage2.
> 
> 
> Regards,
> Gunwant
> 
> [1] https://llvm.org/docs/BuildingADistribution.html
> [2] https://android.googlesource.com/platform/prebuilts/clang/host/linux-x86/