How do I view code generated by a Just-In-Time Compiler?

[David Wake]

I'm curious to know how much inlining is going on in modern
Just-In-Time (JIT) compilers such as Java's hotspot.

Is anyone aware of command-line options or tools that enable the code
generated at runtime by a JIT compiler such as HotSpot to be
inspected?

Thanks,

David

 

[Karsten Baumgarten]

I'm curious to know how much inlining is going on in modern
Just-In-Time (JIT) compilers such as Java's hotspot.

Is anyone aware of command-line options or tools that enable the code
generated at runtime by a JIT compiler such as HotSpot to be
inspected?

http://asm.objectweb.org/eclipse/bco/index.html

They have a plugin for Eclipse and a stand-alone bytecode viewer, if
that is what you were looking for.

 

[David Wake]

http://asm.objectweb.org/eclipse/bco/index.html

They have a plugin for Eclipse and a stand-alone bytecode viewer, if
that is what you were looking for.

Thanks. I didn't try the plugin, but it looks as if it just views the
bytecode generated by the Java compiler, like "javap -c". I'm
interested in the code execution path that's actually followed at
runtime in the JVM. Please let me know if my supposition is wrong.

David

 

[Karsten Baumgarten]

Thanks. I didn't try the plugin, but it looks as if it just views the
bytecode generated by the Java compiler, like "javap -c". I'm
interested in the code execution path that's actually followed at
runtime in the JVM. Please let me know if my supposition is wrong.

David

No, that is exactly what the plugin is all about. A possible approach
would be using the debugger of your choice attached to the JVM process.
After a couple of hours reading ASM you might know what you wanted to.

 

[Thomas Schodt]

I'm curious to know how much inlining is going on in modern
Just-In-Time (JIT) compilers such as Java's hotspot.

You can use these flags
-XX:+PrintCompilation
-XX:+CITime

Is anyone aware of command-line options or tools that enable the code
generated at runtime by a JIT compiler such as HotSpot to be
inspected?

Unfortunately there is no documented user interface to cause Hotspot to
dump its generated code.

 

[Chris Uppal]

Is anyone aware of command-line options or tools that enable the code
generated at runtime by a JIT compiler such as HotSpot to be
inspected?

You could try:

<http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/jvmti.html#CompiledMethodLoad>

but you'll have to find a disassembler for your target machine's architecture.

-- chris