以下是本人学习编译ollvm时的笔记，由于本人水平有限，不足之处还请大家多多指正。
cd /Users/Name/Documents/workspace/llvm/xcodetoolchain
cmake -G Unix\ Makefiles -DLLVM_CREATE_XCODE_TOOLCHAIN=On ../llvm
sudo make install-xcode-toolchain
参考：
https://github.com/obfuscator-llvm/obfuscator/issues/130
From Xcode9 onwards you can just do make install-xcode-toolchain and none of the Plugin hassle
Xcode9及以上用Xcode toolchain
https://stackoverflow.com/questions/23071024/how-do-i-make-xcode-use-an-alternative-version-of-clang
Its an old question, but since I wanted to install more recent clang/libc++ to use with Xcode 9+, here is my solution in hope it would be useful for someone.
- If you are building from source, make sure to pass
-DLLVM_CREATE_XCODE_TOOLCHAIN=ONto cmake, afterwards run make install-xcode-toolchain. If you install with homebrew, use thebrew install --with-toolchain llvm - Copy the toolchain folder from wherewher its installed (/usr/local/Toolchains probably) to /Library/Developer/Toolchains
- Restart Xcode, you will see a Toolchains option in the Xcode menu.
以上是构建xcode toolchain的方法
cmake -G “Unix Makefiles” -DCMAKE_BUILD_TYPE=MinSizeRel -DLLVM_APPEND_VC_REV=on -DLLVM_CREATE_XCODE_TOOLCHAIN=on -DCMAKE_INSTALL_PREFIX=~/Library/Developer/ ../llvm && make && make install-xcode-toolchain
https://github.com/HikariObfuscator/Hikari/wiki/Compile-&-Install
参考 Hikari的 build xcode toolchain 的方法
llvm8.0生成的xcode toolchain 只支持iOS9及以上
更新：上面一行错了，支持iOS8，需要rsync一下，命令如下：
rsync -a –ignore-existing /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/ ~/Library/Developer/Toolchains/LLVM8.0.0svn.xctoolchain/
rm ~/Library/Developer/Toolchains/LLVM8.0.0svn.xctoolchain/ToolchainInfo.plist
参考：https://github.com/HikariObfuscator/Hikari/wiki/Compile-&-Install
另一种替换Clang为可以混淆的版本的方法是：
The easiest option (also the easiest to reverse) is to add the CC build flag. Go to your project’s or target’s build settings, and choose Editor –> Add Build Setting –> Add User-Defined Setting from the menu.
xcode连接真机运行时，报错cannot specify -o when generating multiple output files，解决方法：Build Setting 中搜索 Index-While-Building 设置为 NO 可编译成功
