debug in hotspot

[Krystal Mok]

On 2012-5-4, at 8:16, Xin Tong <xerox.time.tech at gmail.com> wrote:

> i would like to know how to debug in hotspot, what are some of the
> standard procedures ? Lets say, the hotspot fails to run a Java
> program. a few steps to triage the problem.
> 
> 1. disable JIT compilers. hotspot has 2 compilers c1 and c2. they are
> both used if TieredCompilation is enabled. How do I disable both of
> them.

It's there in the globals.hpp file: -XX:-UseCompiler

> 2. if the Java program passes after the JIT is disabled. There is a
> good chance that the problem is cause by the JIT. I want to narrow
> down to a specific method, I can use PrintCompilation to find out all
> the method compiled, but how can I disable one specific method from
> being compiled.

-XX:CompileCommand='exclude,your/class,yourMethod'
Or an equivalent .hotspot_compiler configuration file.
Read this thread for example (in Chinese): http://hllvm.group.iteye.com/group/topic/28201

> 3. if i am able to limit down to a specific method, i want to start
> disabling optimizations, is there an option to disable all
> optimizations in the c1 and c2 compilers, or i need to do it manually
> ?
> 

I don't think there's an all-in-one flag to turn all optimizations off. At least not for now.
See c1_globals.hpp and c2_globals.hpp to get an idea of what optimizations you can turn off.

- Kris

> Thanks