JDK源码编译

1. 源码准备

1.1 源码版本及下载

确定要编译哪个版本的JDK，有两种方法：

Github：https://github.com/openjdk/jdk 可以从github找到对应的版本来下载
Java.Net: https://jdk.java.net/java-se-ri/18 也可以去次网站直接下载源码压缩包。

我这里是通过第二种方式下载的，下载的是：openjdk_18+36版本。

godwit@Firebase  ~/Source  ll
total 339496
drwxr-xr-x@ 19 godwit  staff   608B  5  2 22:15 openjdk-18+36
-rw-r--r--@  1 godwit  staff   166M  5  2 22:11 openjdk-18+36_src.zip
 godwit@Firebase  ~/Source  cd openjdk-18+36
 godwit@Firebase  ~/Source/openjdk-18+36 

2. 环境准备

2.1 Bootstrap JDK

假设需要编译大版本号为N的JDK，那么我们需要另外准备一个大版本号至少为N-1的，已经编译好的JDK，这是因为OpenJDK由多个部分构成，其中一部分（HotSpot）代码是用C、C++编写，而更多的代码是用Java语言来实现的。因此编译这些Java代码就需要使用另外一个编译期可用的JDK，官方称这个为Bootstrap JDK。

我本机已经安装了JDK环境，直接使用即可。

godwit@Firebase  ~  java -version
java 17.0.2 2022-01-18 LTS
Java(TM) SE Runtime Environment (build 17.0.2+8-LTS-86)
Java HotSpot(TM) 64-Bit Server VM (build 17.0.2+8-LTS-86, mixed mode, sharing)

2.2 其他依赖库

缺少什么，直接brew install xxx即可。

FreeType：
Autoconf：
ccache：
clang/clang++: XCode自带，所以没有额外配置安装。

godwit@Firebase  ~  clang --version
Apple clang version 13.1.6 (clang-1316.0.21.2.3)
Target: arm64-apple-darwin21.4.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

godwit@Firebase  ~  clang++ --version
Apple clang version 13.1.6 (clang-1316.0.21.2.3)
Target: arm64-apple-darwin21.4.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

godwit@Firebase  ~  autoconf --version
autoconf (GNU Autoconf) 2.71
Copyright (C) 2021 Free Software Foundation, Inc.
License GPLv3+/Autoconf: GNU GPL version 3 or later
<https://gnu.org/licenses/gpl.html>, <https://gnu.org/licenses/exceptions.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by David J. MacKenzie and Akim Demaille.

godwit@Firebase  ~  make --version
GNU Make 3.81
Copyright (C) 2006  Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.

This program built for i386-apple-darwin11.3.0

godwit@Firebase  ~  freetype-config --ftversion
2.12.0

3. 编译

3.1 配置

# --with-debug-level=slowdebug参数是为了显示更多调试信息.debug level有4种：release, fastdebug, slowdebug, optimized. 默认是 release
# --with-native-debug-symbols hotspot编译之后是一个名为libjvm.so的动态库,在java命令里通过dlopen加载,如果不加上--with-native-debug-symbols=internal,需要手动解压jdk/lib/amd64/server里的libjvm.debuginfo,或者指定动态库路径,调试起来会很复杂.
# --with-jvm-variants=server：仅包含Server模式
# --disable-warnings-as-errors：因为tag版本可能还不是很完美，存在warning，所以这里允许warning的存在
$ bash ./configure  --with-debug-level=slowdebug --with-native-debug-symbols=internal --with-jvm-variants=server --enable-dtrace --disable-warnings-as-errors

3.1.1 错误1 - No xcodebuild tool and no system framework headers found

...
checking which variants of the JVM to build... server
checking if absolute paths should be allowed in the build output... no, release build
checking for sdk name...
configure: error: No xcodebuild tool and no system framework headers found, use --with-sysroot or --with-sdk-name to provide a path to a valid SDK
/Users/godwit/Source/openjdk-18+36/build/.configure-support/generated-configure.sh: line 84: 5: Bad file descriptor
configure exiting with result code 1
 ✘ godwit@Firebase  ~/Source/openjdk-18+36 
#### 解决方案如下：
 ✘ godwit@Firebase  ~/Source/openjdk-18+36  sudo xcode-select --switch /Applications/Xcode.app/Contents/Developer
Password:
 godwit@Firebase  ~/Source/openjdk-18+36 

3.1.2 错误2 - error: parameter ‘SizeOfTag’ set but not used

=== Output from failing command(s) repeated here ===
* For target support_native_java.desktop_liblcms_cmstypes.o:
/Users/godwit/Source/openjdk-18+36/src/java.desktop/share/native/liblcms/cmstypes.c:3441:132: error: parameter 'SizeOfTag' set but not used [-Werror,-Wunused-but-set-parameter]
void *Type_ProfileSequenceId_Read(struct _cms_typehandler_struct* self, cmsIOHANDLER* io, cmsUInt32Number* nItems, cmsUInt32Number SizeOfTag)
                                                                                                                                   ^
/Users/godwit/Source/openjdk-18+36/src/java.desktop/share/native/liblcms/cmstypes.c:5137:125: error: parameter 'SizeOfTag' set but not used [-Werror,-Wunused-but-set-parameter]
void *Type_Dictionary_Read(struct _cms_typehandler_struct* self, cmsIOHANDLER* io, cmsUInt32Number* nItems, cmsUInt32Number SizeOfTag)
                                                                                                                            ^
2 errors generated.

* All command lines available in /Users/godwit/Source/openjdk-18+36/build/macosx-aarch64-server-release/make-support/failure-logs.
=== End of repeated output ===

### 解决方法：--disable-warnings-as-errors

3.1.3 配置成功

出现以下输出，说明配置成功。


......
====================================================
A new configuration has been successfully created in
/Users/godwit/Source/openjdk-18+36/build/macosx-aarch64-server-release
using default settings.

Configuration summary:
* Name:           macosx-aarch64-server-release
* Debug level:    release
* HS debug level: product
* JVM variants:   server
* JVM features:   server: 'cds compiler1 compiler2 dtrace epsilongc g1gc jfr jni-check jvmci jvmti management nmt parallelgc serialgc services shenandoahgc vm-structs zgc'
* OpenJDK target: OS: macosx, CPU architecture: aarch64, address length: 64
* Version string: 18-internal+0-adhoc.godwit.openjdk-1836 (18-internal)

Tools summary:
* Boot JDK:       java version "17.0.2" 2022-01-18 LTS Java(TM) SE Runtime Environment (build 17.0.2+8-LTS-86) Java HotSpot(TM) 64-Bit Server VM (build 17.0.2+8-LTS-86, mixed mode, sharing) (at /Library/Java/JavaVirtualMachines/jdk-17.0.2.jdk/Contents/Home)
* Toolchain:      clang (clang/LLVM from Xcode 13.3)
* C Compiler:     Version 13.1.6 (at /usr/bin/clang)
* C++ Compiler:   Version 13.1.6 (at /usr/bin/clang++)

Build performance summary:
* Build jobs:     10
* Memory limit:   32768 MB

4. 编译

4.1 make

1	godwit@Firebase  ~/Source/openjdk-18+36  make all

4.2 错误 - guarantee(val < (1ULL << nbits)) failed: Field too big for insn

=== Output from failing command(s) repeated here ===
* For target jdk__optimize_image_exec:
#
# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (assembler_aarch64.hpp:250), pid=72987, tid=9731
#  guarantee(val < (1ULL << nbits)) failed: Field too big for insn
#
# JRE version:  (18.0) (build )
# Java VM: OpenJDK 64-Bit Server VM (18-internal+0-adhoc.godwit.openjdk-1836, mixed mode, sharing, tiered, compressed oops, compressed class ptrs, g1 gc, bsd-aarch64)
# No core dump will be written. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# An error report file with more information is saved as:
# /Users/godwit/Source/openjdk-18+36/make/hs_err_pid72987.log
#
#

* All command lines available in /Users/godwit/Source/openjdk-18+36/build/macosx-aarch64-server-release/make-support/failure-logs.
=== End of repeated output ===

No indication of failed target found.
Hint: Try searching the build log for '] Error'.
Hint: See doc/building.html#troubleshooting for assistance.

make[1]: *** [main] Error 2
make: *** [all] Error 2

解决方案：

可以根据commit修改一下src/hotspot/cpu/aarch64/immediate_aarch64.cpp
// src/hotspot/cpu/aarch64/immediate_aarch64.cpp 
uint64_t replicate(uint64_t bits, int nbits, int count)
{
  // 在函数开头，添加下main代码 
  assert(count > 0, "must be");
  assert(nbits > 0, "must be");
  assert(count * nbits <= 64, "must be");

  // Special case nbits == 64 since the shift below with that nbits value
  // would result in undefined behavior.
  if (nbits == 64) {
    return bits;
  }
  //-----------------------

  uint64_t result = 0;
  uint64_t mask = ones(nbits);

4.3 编译成功

编译成功后，在build/macosx-aarch64-server-slowdebug/jdk/bin目录下执行：java -version

能够看到正常输出。

✘ godwit@Firebase  ~/Source/openjdk-18+36/build/macosx-aarch64-server-slowdebug/jdk/bin  java -version
openjdk version "1.8.0_322"
OpenJDK Runtime Environment (Zulu 8.60.0.21-CA-macos-aarch64) (build 1.8.0_322-b06)
OpenJDK 64-Bit Server VM (Zulu 8.60.0.21-CA-macos-aarch64) (build 25.322-b06, mixed mode)