环境:
os: MAC OS X 10.10.1 yosemite
target build OPENJDK：jdk8
Xcode:6.1
LLVM Version：

Apple LLVM version 6.0 (clang-600.0.54) (based on LLVM 3.5svn)

Target: x86_64-apple-darwin14.0.0

Thread model: posix

步骤：
1 国内hg拉取代码不靠谱，到这里打包下载，118M  
http://download.java.net/openjdk/jdk8/

2  安装X11 ，系统默认好像是没有这个东西，需要下载安装 XQuartz ，然后link下  sudo ln -s /usr/X11/include/X11 /usr/include/X11
 3 
 sudo ln -s /usr/bin/llvm-g++ /Applications/Xcode.app/Contents/Developer/usr/bin/llvm-g++  
 sudo ln -s /usr/bin/llvm-gcc /Applications/Xcode.app/Contents/Developer/usr/bin/llvm-gcc
4 安装 Xcode的 Command line tools 、freetype
5  ./configure --enable-debug --with-target-bits= 64
 6 cd jdk8;
unset JAVA_HOME
unset CLASSPATH 
make CC=clang COMPILER_WARNINGS_FATAL=false LFLAGS='-Xlinker -lstdc++' USE_CLANG=true LP64=1 LANG=C ALT_BOOTDIR=/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home ARCH_DATA_MODEL=64 HOTSPOT_BUILD_JOBS=8 ALT_FREETYPE_HEADERS_PATH=/Users/mungo/Downloads/work/homebrew-master/Cellar/freetype/2.5.5/include ALT_FREETYPE_LIB_PATH=/Users/mungo/Downloads/work/homebrew-master/Cellar/freetype/2.5.5/lib
7 验证结果：

./build/macosx-x86_64-normal-server-fastdebug/jdk/bin/java -version

openjdk version "1.8.0-internal-fastdebug"

OpenJDK Runtime Environment (build 1.8.0-internal-fastdebug-mungo_2015_01_29_16_11-b00)

OpenJDK 64-Bit Server VM (build 25.0-b70-fastdebug, mixed mode)
出现的问题：

1  clang: error: unknown argument: '-fcheck-new' [-Wunused-command-line-argument-hard-error-in-future]  

         于是直接打开YourOpenJDK/hotspot/make/bsd/makefiles/gcc.make，把这行（line 193）给注释掉
2 relocInfo.hpp错误。 将接口的默认值去掉，把默认值放到的方法参数里即可。hotspot/src/share/vm/code/relocInfo.hpp 
+ inline friend relocInfo prefix_relocInfo(int datalen);

+inline relocInfo prefix_relocInfo(int datalen = 0) {
   assert(relocInfo::fits_into_immediate(datalen), "datalen in limits");
   return relocInfo(relocInfo::data_prefix_tag, relocInfo::RAW_BITS, relocInfo::datalen_tag | datalen);
 }

参考文章：
1 http://hllvm.group.iteye.com/group/topic/39814
2 http://yueyemaitian.iteye.com/blog/2038304

另:openjdk 7 hotspot我可以编译成功，但是最后打包的时候，出现 执行cp 错误.没找到原因