Use Qualcomm Snapdragon LLVM Compiler 3.6 (https://developer.qualcomm.com/mobile-development/increase-app-performance/snapdragon-llvm-compiler-android) for Android Lollipop 5.0.2 for devices with Qualcomm CPU

As far as I know nobody has done that yet. Except me :)

This changes the toolchain for CLANG from the default one which comes with Android (aCLANG) to the Qualcomm Snapdragon LLVM Compiler 3.6 (qCLANG) mentioned above. The toolchain will be used for almost all places where the default Android CLANG (aCLANG) is used for compiling TARGET MODULES. BUT ONLY if "USE_CLANG_QCOM := true" is set. Otherwise it is using aCLANG. So you can merge this commit and the build will be the same as before except you specifically define "USE_CLANG_QCOM := true".

WARNING: THIS IS NOT FULLY TESTED FOR STABILITY YET. READ CAREFULLY It is very likely that using this toolchain, especially with the optimizations flags, will introduce BUGS!

I would suggest: IF YOU USE IT DONT MAKE BUG REPORTS FOR YOUR OFFICIAL ROM OR KERNEL OR ANY APPS. Make reports in the development thread. The ROM compiles, boots and starts. Also if Bionic and other modules are compiled with Qualcomm Snapdragon LLVM Compiler 3.6 (qCLANG). Androbench, Antutu, Basemark 2.0 , Geekbench 3, Vellamo are 'completing' the bechmarks. This is a work in progress. Only tried this on my personal device (Sony Xperia Z Ultra [C6833] with Krait 400) with Validus ROM (https://plus.google.com/communities/...59573276360638). And this kernel: https://github.com/Tommy-Geenexus/android_kernel_sony_msm8974 If you use Validus ROM for Sony Xperia Z line you have to change the androideabi toolchain manually to the default one from google. Otherwise the device wont boot. (18.02.2015). This havs nothing to do with qCLANG.

At the moment this is only tested with Krait 400/Snapdragon 800 but in theory should also work with any Krait and even Scorpion CPU. According to Documentation there is also support for armv8/aarch64 (Snapdragon 810) but support is not yet implemented.

Install instructions:

1. You have to make an account in order to download the toolchain!
2. You need to download the toolchain and extract it to {your android dir}/prebuilts/clang/linux-x86/host/*
3. Add the repo (https://github.com/mustermaxmueller/clanglibs) to your manifest and copy it to {your android dir}/vendor/clanglibs/ For example:
4. Add the repo (https://github.com/mustermaxmueller/compiler-rt) to your manifest and copy it to {your android dir}/vendor/clanglibs/ For example:
5. Add "USE_CLANG_QCOM := true" to your Boardconfig.mk/BoardconfigCommon.mk of your device.
6. use my build repo https://github.com/mustermaxmueller/validus_build/ or merge my changes. For example:
7. make a clean compile! Also delete ccache!
8. give feedback

I could have made the installation easier by uploading the toolchain to Github but I do not know if I am allowed to. And I am no lawyer so...

Annotation:

1. You should only get measurable performance benefits if you compile Bionic with CLANG! See here: https://github.com/mustermaxmueller/...05929de3d86e2c
2. Documentation for the toolchain: {your android dir}/prebuilts/clang/linux-x86/host/llvm-Snapdragon_LLVM_for_Android_3.6/Snapdragon_LLVM_ARM_36_User_Guide.pdf
3. The Flag "-muse-optlibc" is not Documented.
4. The implementation is not beautiful but it works
5. "frameworks/rs/driver/runtime/build_bc_lib_internal.mk" still uses aCLANG. There might be some other places I missed.
6. HOST is compiled with aCLANG because qCLANG does not understand x86
7. Setting "USE_CLANG_QCOM_VERBOSE := true" will give some extra Verbose information while compiling.
8. LTO not working at the moment

TODO: -Make more performance comparisons to aCLANG and GCC. It seems good even compared to GCC -Use ccache -Where does it make sense to use qCLANG instead of GCC? -Compile Android with qCLANG wherever possible. http://www.linuxplumbersconf.org/2013/ocw/system/presentations/1131/original/LP2013-Android-clang.pdf and https://events.linuxfoundation.org/sites/events/files/slides/2014-ABS-LLVMLinux.pdf -Test -falign-functions -falign-labels -falign-loops also set -falign-os when -Os is set -Test -fdata-sections -finline-functions -"-fparallel" where to use? see 3.6.4 -"-ffp-contract=fast" maybe to dangerous

Development Thread: http://forum.xda-developers.com/android/software-hacking/wip-compile-android-5-0-2-qualcomm-llvm-t3035162