[Android Software/Hacking General [Developers Only]] frap129:
DragonTC is a build system for compiling custom clang toolchains. These toolchains contain some AOSP patches(where applicable) and things not included in AOSP clang, such as LTO and Gold plugins, and OpenMP, Polly compiled and automatically linked into tools, improved krait optimizations (-mcpu=krait2), and annoying flags such as -Werror, -Wfatal-errors, and -Weverything internally disabled for non-default parameters. DragonTC compilers are also built with -O3, -pthread, and -fopenmp in order to reduce compile time when used for ROMs. DragonTC has been around for a few months now, but now that some testers have helped me work out the bugs and make it close to stable, I've decided to make an XDA thread.

Why use custom Clang?

Google has been slowly moving away from GCC for a while now, so we believe that we should get ahead of the toolchain game and start now! Furthermore, AOSP modules that are compiled with clang can easily be optimized with the new LTO and Polly options.

How do I build DragonTC?

It's simple! Run the following commands in bash to get set up:

$ mkdir dtc
$ cd dtc
$ repo init -u https://github.com/dragon-tc/DragonTC -b master
$ repo sync -j(# of cores) -c -f

For Debian and Ubuntu:

sudo aptitude install build-essential git git-svn bc binfmt-support libllvm-3.6-ocaml-dev llvm-3.6 llvm-3.6-dev llvm-3.6-runtime cmake automake autogen autoconf autotools-dev libtool shtool python m4 gcc libtool zlib1g-dev

And run the following to build your desired toolchain:

$ cd build
$ ./version

Where "version" is 3.6. 3.7, 3.8, or 3.9.

To optimize the toolchain for your local system, run with the 'opt' argument. Example:

$ ./3.7 opt

How do use DragonTC in AOSP?

Either clone a prebuilt or build your own toolchain and place it in prebuilts/clang/linux-x86/host/your_version (3.7 is the prefered version)

Change the version in build/core/clang/config.mk to reflect the directory you placed it in.

Either clone ours, or cherry-pick our changes to prebuilts/ndk and frameworks/rs.

Cherry-pick our DragonTC support commit in build.

Edit build/core/clang/config.mk and set "TARGET_DRAGONTC_VERSION := " to the name of the folder you placed the toolchain in (your_version is the example used above)

How can I fix module issues when compiling with Polly?

It's simple. Just take the module name (ex. "target C++: module_name_here <= some/path/to/code") and add it to the DISABLE_POLLY list. You can also disable Clang all together, use AOSP clang, or force GCC modules to use Clang.

Why call it DragonTC?

The LLVM logo/mascot is a dragon, so in homage to the developers of LLVM and Clang, I used DragonTC as the name.

Credits

A huge thanks to all of the people who helped:

xboxfanj for recreating the Snapdragon Compiler optimizations

xanaxdroid for maintenance, bug fixes, and testing

The LLVM developers for the great work and continuous improvement

All of the great devs/rom builders that helped test

and anyone that I missed!

XDA:DevDB Information

DragonTC, Tool/Utility for the Android General

Contributors

frap129, xanaxdroid

Source Code: https://github.com/dragon-tc

Version Information

Status: Beta

Created 2016-02-19

Last Updated 2016-05-21