这些说明适用于Linux（Ubuntu 10.04.4 LTS），但应适用于您的OS。在下载Oracle JDK
7u3并适当设置了您
JAVA_HOME和
PATH环境变量之后，执行以下步骤检查可用选项：
java -XX:+AggressiveOpts -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+PrintFlagsFinal -version
您应该看到
UnlockDiagnosticVMOptions，
CompileCommand并且
PrintAssembly选项可用。使用该
CompileCommand选项还将启用该
PrintAssembly选项。但是，您将需要使用HotSpot反汇编程序插件
PrintAssembly才能工作。没有它，您可能会看到类似以下的内容：
$ java -versionjava version "1.7.0_03"Java(TM) SE Runtime Environment (build 1.7.0_03-b04)Java HotSpot(TM) Server VM (build 22.1-b02, mixed mode)$ java -server -XX:+UnlockDiagnosticVMOptions '-XX:CompileCommand=print,*Main.main' MainCompilerOracle: print *Main.mainJava HotSpot(TM) Server VM warning: printing of assembly pre is enabled; turning on DebugNonSafepoints to gain additional outputCompiled method (c2) 68 1 %Main::main @ 4 (49 bytes) total in heap [0xb3a97548,0xb3a979ec] = 1188 relocation [0xb3a97610,0xb3a97624] = 20 main pre [0xb3a97640,0xb3a97840] = 512 stub pre [0xb3a97840,0xb3a97850] = 16 oops[0xb3a97850,0xb3a97858] = 8 scopes data [0xb3a97858,0xb3a97898] = 64 scopes pcs [0xb3a97898,0xb3a979e8] = 336 dependencies [0xb3a979e8,0xb3a979ec] = 4Could not load hsdis-i386.so; library not loadable; PrintAssembly is disabledOopMapSet contains 1 OopMaps
要获取HotSpot反汇编程序插件，您需要对其进行构建。查看OpenJDK
7u2源，hsdis插件自述文件说：
要将插件与JVM一起使用，您需要一个可以加载它的新版本。如果JVM的产品模式不接受-XX：+ PrintAssembly，则您没有足够新的版本。
要构建该项目，需要[GNU binutils]副本。
从理论上讲，它应该可以在Windows上构建，但是事实证明，要在Windows上创建一个可运行的GNU构建环境是困难的。
上面我们已经确认Oracle JDK 7u3支持
PrintAssembly。我遵循了hsdis插件自述文件的说明，下载了GNU binutils
2.22，将其放在hsdis
build/binutils目录中并运行
make。这最终产生了以下错误：
hsdis.c:32:20: error: sysdep.h: No such file or directory
为了解决这个问题，我使用以下补丁更改了hsdis.c：
diff -r 6259c6d3bbb7 src/share/tools/hsdis/hsdis.c--- a/src/share/tools/hsdis/hsdis.c Mon Dec 12 23:08:01 2011 -0800+++ b/src/share/tools/hsdis/hsdis.c Thu Feb 23 09:26:37 2012 -0500@@ -29,7 +29,7 @@ #include "hsdis.h"-#include <sysdep.h>+#include <errno.h> #include <libiberty.h> #include <bfd.h> #include <dis-asm.h>
跑步
make成功了。现在，只需将
hsdis-i386.sohsdis
build目录中的插件复制到Oracle JDK 7u3
jre/lib/i386目录。
现在您可以看到反汇编的编译代码：
$ java -server -XX:+UnlockDiagnosticVMOptions '-XX:CompileCommand=print,*Main.main' MainCompilerOracle: print *Main.mainJava HotSpot(TM) Server VM warning: printing of assembly pre is enabled; turning on DebugNonSafepoints to gain additional outputCompiled method (c2) 68 1 %Main::main @ 4 (49 bytes) total in heap [0xb3999548,0xb39999ec] = 1188 relocation [0xb3999610,0xb3999624] = 20 main pre [0xb3999640,0xb3999840] = 512 stub pre [0xb3999840,0xb3999850] = 16 oops[0xb3999850,0xb3999858] = 8 scopes data [0xb3999858,0xb3999898] = 64 scopes pcs [0xb3999898,0xb39999e8] = 336 dependencies [0xb39999e8,0xb39999ec] = 4Loaded disassembler from [snip]/jdk1.7.0_03/jre/lib/i386/hsdis-i386.soDecoding compiled method 0xb3999548:Code:[Disassembling for mach='i386'][Entry Point][Verified Entry Point][Constants] # {method} 'main' '([Ljava/lang/String;)V' in 'Main' 0xb3999640: call 0xb6ff8510 ; {runtime_call} 0xb3999645: data32 xchg %ax,%ax 0xb3999648: mov %eax,-0x3000(%esp) 0xb399964f: push %ebp 0xb3999650: sub $0x38,%esp 0xb3999656: mov %ecx,%esi 0xb3999658: mov 0x4(%esi),%ebp 0xb399965b: mov 0x8(%esi),%edi 0xb399965e: mov (%ecx),%esi 0xb3999660: mov %ecx,(%esp) 0xb3999663: call 0xb7078cf0 ;*iload_3[snip] 0xb399983e: hlt 0xb399983f: hlt [Exception Handler][Stub Code] 0xb3999840: jmp 0xb39981e0 ; {no_reloc}[Deopt Handler Code] 0xb3999845: push $0xb3999845 ; {section_word} 0xb399984a: jmp 0xb397e220 ; {runtime_call} 0xb399984f: .byte 0x0OopMapSet contains 1 OopMaps#0 OopMap{off=468}我使用的测试类是：
public class Main { public static void main(final String[] args) { long x = 0; for (int i = 0; i < 1000000; i++) { x += calculate(i); } System.out.println("x=" + x); } private static long calculate(final int i) { return (long)i * (long)i; }}
