java: How to get PrintAssembly

Thanks to Roman Yaroslavtsev who gave me a link to an article Memory Barriers and JVM Concurrency.

First of all this article is useful to gain a better understanding of Java Memory Model - another great thing that I discover is ability to look inside of assembly code generated by jit.

Refer to load-test-tool usage I going to use that simple example:

public class ArrayIterationTest {

  private final int[] data;

  public ArrayIterationTest(final int size) {
    this.data = new int[size];
  }

  public void doTest() {
    for ( int i = 0; i < data.length; i++ ){
  int j = data[i]; 
 }
  }

  public static final void main(String[] args){
   final long t0 = System.nanoTime(); 
   ArrayIterationTest t = new ArrayIterationTest(1000000);
   t.doTest();
   System.out.println((System.nanoTime() - t0) / 1000 / 1e3);
  }
}

Let's start it (user's jvm is sun jdk 1.6.0_20):

java -XX:+UnlockDiagnosticVMOptions
-XX:+PrintAssembly -XX:PrintAssemblyOptions=hsdis-print-bytes
-XX:CompileCommand=print,ArrayIterationTest
ArrayIterationTest

and have got

CompilerOracle: print ArrayIterationTest
Could not load hsdis-i386.so; library not loadable; PrintAssembly is disabled
14.029

So...

Dude, where's my hsdis-i386.so ?

There is no hsdis-i386.so in dev-java/sun-jdk-1.6.0.20, nor in dev-java/sun-jdk-1.7.0.0_alpha89 or in dev-java/icedtea6-bin-1.8.0

Let's fetch openjdk plugin implementation

hg clone http://hg.openjdk.java.net/jdk7/hotspot/hotspot/src/share/tools/hsdis/ openjdk-hotspot

and build it using hsdis's README

This version of the plugin requires the Gnu disassembler, which is available separately as part of the binutils project.

cd openjdk-hotspot/src/share/tools/hsdis/
mkdir build && cd build
wget http://ftp.gnu.org/gnu/binutils/binutils-2.20.1.tar.bz2 
tar jxf binutils-2.20.1.tar.bz2 && mv binutils-2.20.1 binutils && cd ..
make

and start again it now:

LD_LIBRARY_PATH=openjdk-hotspot/src/share/tools/hsdis/build/linux-i586/:$LD_LIBRARY_PATH
java -XX:+UnlockDiagnosticVMOptions
-XX:+PrintAssembly -XX:PrintAssemblyOptions=hsdis-print-bytes
-XX:CompileCommand=print,ArrayIterationTest
ArrayIterationTest

Note: use your own path to hsdis-arch.so in LD_LIBRARY_PATH .

And you've got something like this for your platform:

CompilerOracle: print ArrayIterationTest
Loaded disassembler from hsdis-i386.so
Decoding compiled method 0xb3bb5c48:
Code:
[Disassembling for mach='i386']
[Entry Point]
[Verified Entry Point]
  0xb3bb5d20: call   0xb7168b60         ;...e83b2e5b 03
                                        ;   {runtime_call}
  0xb3bb5d25: xchg   %ax,%ax            ;...666690
  ...

ps. for further information please refer to PrintAssembly at wikis.sun.com as well as for prebuild hsdis-i386.dll