关于macos:macos平台上编译jdk源码

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对于 java 来说，很多工作都被 jvm 包揽了，比方内存调配和回收、其余零碎级别调用。这其实就把操作系统底层的一些货色给屏蔽了，对于 javaer 来说，不便的同时也带来一些困惑（我还不是一个纯 javaer），很多细节性概念始终不是很通透，特地是当波及底层交互的时候。特地是学 NIO 那块货色的时候（epoll&poll？、zero-copy？、userbuffer？、kernel buffer？）。

为了解决心田的种种纳闷，还是筹备学习 jdk 的底层源码。首先须要下载 jdk 源码，并在本地编译，上面开整（还是有很多坑）：

macOS Monterey 12.0.1;
须要装置 XCode【下载地址】，本地装置版本 13.1;
brew install freetype & brew install ccache

首先下载 JDK9 源码，下载地址:https://github.com/campolake/…;

在源码根目录执行如下命令（环境检查和配置）：
bash ./configure --with-debug-level=slowdebug --with-jvm-variants=server --enable-ccache --with-freetype=/usr/local/Cellar/freetype/2.11.0 --disable-warnings-as-errors

freetype（字体引擎）门路依据本地环境本人更改；

ccache缓存编译代码，减速编译，能够不必；

disable-warnings-as-errors防止将 warning 信息当成 error；

with-debug-level用来设置编译的级别，可选值为 release、fastdebug、slowde-bug，越往后进行的优化措施就越少，带的调试信息就越多。

执行完呈现如下提醒就示意能够下一步了：

 A new configuration has been successfully created in
 /Users/***/CLionProjects/openjdk9/build/macosx-x86_64-normal-server-slowdebug
 using configure arguments '--with-debug-level=slowdebug --with-jvm-variants=server --enable-ccache --with-freetype=/usr/local/Cellar/freetype/2.11.0 --disable-warnings-as-errors'.
 
 Configuration summary:
 * Debug level:    slowdebug
 * HS debug level: debug
 * JDK variant:    normal
 * JVM variants:   server
 * OpenJDK target: OS: macosx, CPU architecture: x86, address length: 64
 * Version string: 9-internal+0-2021-12-03-105259.***.openjdk9 (9-internal)
 
 Tools summary:
 * Boot JDK:       java version "1.8.0_281" Java(TM) SE Runtime Environment (build 1.8.0_281-b09) Java HotSpot(TM) 64-Bit Server VM (build 25.281-b09, mixed mode)  (at /Library/Java/JavaVirtualMachines/jdk1.8.0_281.jdk/Contents/Home)
 * Toolchain:      clang (clang/LLVM from Xcode 13.1)
 * C Compiler:     Version 13.0.0 (at /usr/bin/clang)
 * C++ Compiler:   Version 13.0.0 (at /usr/bin/clang++)
 
 Build performance summary:
 * Cores to use:   16
 * Memory limit:   32768 MB
 * ccache status:  Active (4.5.1)
 
 The following warnings were produced. Repeated here for convenience:
 WARNING: Ignoring value of CCACHE from the environment. Use command line variables instead.

执行 make images，开始编译；
事件当然没有那么简略，在这一步胜利呈现了报错，如下：

/Users/yulewei/jdk9/hotspot/src/share/vm/memory/virtualspace.cpp:585:14: error: ordered comparison between pointer and zero ('char *' and 'int')
if (base() > 0) {
   ~~~~~~ ^ ~
...
/Users/yulewei/jdk9/hotspot/src/share/vm/opto/lcm.cpp:42:35: error: ordered comparison between pointer and zero ('address' (aka 'unsigned char *') and 'int')
if (Universe::narrow_oop_base() > 0) { // Implies UseCompressedOops.
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~ 
...
/Users/yulewei/jdk9/hotspot/src/share/vm/opto/loopPredicate.cpp:915:73: error: ordered comparison between pointer and zero ('const TypeInt *' and 'int')
   assert(rng->Opcode() == Op_LoadRange || _igvn.type(rng)->is_int() >= 0, "must be");
                                           ~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~

这个是 JDK9 的 bug，须要批改源码文件而后从新编译，参考这篇文章解决：https://segmentfault.com/a/11…

改完源码文件从新编译，呈现新的报错：

* For target hotspot_variant-server_libjvm_gtest_objs_gtestMain.o:
clang: warning: include path for libstdc++ headers not found; pass   '-stdlib=libc++' on the command line to use the libc++ standard     library instead [-Wstdlibcxx-not-found]
In file included from      /Users/***/CLionProjects/openjdk9/hotspot/test/native/gtestMain.cpp :33:
In file included from  /Users/***/CLionProjects/openjdk9/hotspot/test/native/unittest.hpp: 29:
/Users/***/CLionProjects/openjdk9/test/fmw/gtest/include/gtest/gtest.h:54:10: fatal error: 'limits' file not found
#include <limits>
      ^~~~~
1 error generated.
* For target hotspot_variant-server_libjvm_gtest_objs_test_os.o:
clang: warning: include path for libstdc++ headers not found; pass '-stdlib=libc++' on the command line to use the libc++ standard library instead [-Wstdlibcxx-not-found]
In file included from /Users/***/CLionProjects/openjdk9/hotspot/test/native/runtime/test_os.cpp:25:
In file included from /Users/***/CLionProjects/openjdk9/hotspot/src/share/vm/runtime/os.hpp:29:
In file included from /Users/***/CLionProjects/openjdk9/hotspot/src/share/vm/runtime/extendedPC.hpp:28:
/Users/***/CLionProjects/openjdk9/hotspot/src/share/vm/memory/allocation.hpp:38:10: fatal error: 'new' file not found
#include <new>
      ^~~~~

这个问题是因为 XCode 版本比拟新导致，找不到 C 语言相干的头文件。其实 XCode 中是有的，只是门路和老的不一样了，在 configure 命令中增加如下 3 个参数就行：
--with-extra-cflags=-stdlib=libc++ --with-extra-cxxflags=-stdlib=libc++ --with-extra-ldflags=-stdlib=libc++。

configure 命令就是这样的了：

bash ./configure --with-debug-level=slowdebug --with-jvm-variants=server --enable-ccache --with-freetype=/usr/local/Cellar/freetype/2.11.0  --disable-warnings-as-errors --with-extra-cflags=-stdlib=libc++ --with-extra-cxxflags=-stdlib=libc++ --with-extra-ldflags=-stdlib=libc++

再一次执行 make images
呈现如下报错：

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGILL (0x4) at pc=0x0000000106321898, pid=39315, tid=8195
#
# JRE version: OpenJDK Runtime Environment (9.0) (slowdebug build 9-internal+0-2021-12-03-133118.chensheng.openjdk9)
# Java VM: OpenJDK 64-Bit Server VM (slowdebug 9-internal+0-2021-12-03-133118.chensheng.openjdk9, mixed mode, tiered, compressed oops, serial gc, bsd-amd64)
# Problematic frame:
# V  [libjvm.dylib+0xc1e898]  PerfData::~PerfData()+0x8
#
# No core dump will be written. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.java.com/bugreport/crash.jsp
#

google 了一圈，有的说是硬件问题，最初切实没搞定，就换成 JDK11 了。

首先须要先在本地装置 jdk11（jdk11 能够用来编译 jdk11，不须要低一个版本的 jdk），能够间接下载压缩包而后解压（不须要配置环境变量）
下载 JDK11 源码：https://github.com/openjdk/jd…

执行configure

bash ./configure --with-debug-level=slowdebug --with-boot-jdk=/Users/***/Applications/jdk11/jdk-11.0.12.jdk/Contents/Home --with-jvm-variants=server --enable-ccache --disable-warnings-as-errors --with-extra-cflags=-stdlib=libc++ --with-extra-cxxflags=-stdlib=libc++ --with-extra-ldflags=-stdlib=libc++