Tim Ellison said the following on 13.12.2007 13:51:
Gregory Shimansky wrote:
Tim Ellison said the following on 12.12.2007 21:05:
Gregory Shimansky wrote:
On 12 декабря 2007 Pavel Ozhdikhin wrote:
I've added several comments about new JIT features/optimizations.
I think the following item should be removed from the list:
- 'full speed debug' : debugging with JIT enabled
It seems Gregory's comment was misinterpreted - he probably meant
that the
JIT-mode JVMTI debugging now works on x86_64. AFAIK it worked fine
on IA32
in M3. Gregory, could you please confirm?
Yes, what I meant is that now it is possible to debug applications in
default (JIT) mode on x86_64. Previously in M3 this mode worked only
on x86, on x86_64 it was necessary to use -Xint to use interpreter.
I'm sorry, that was my fault. I misunderstood. So what does 'debug
applications in default JIT mode' mean?
It means that debugged application's bytecode is compiled, not interpreted.
So that's what I mean by 'full speed debugging' -- usually written in
quotes since it typically isn't really 'full speed'. Certain aggressive
JIT optimizations will have to be turned off to permit debugging.
Are we talking about the same thing?
Yes, with an exception that no optimizations are done when a program is
debugged. But execution is still much faster than when the code is
interpreted.
e.g. http://java.sun.com/j2se/1.4.2/docs/guide/jpda/enhancements.html#fsd
Sun doesn't describe whether they do any compiling optimization in this
mode, maybe they do the same thing and call it FSD :)
--
Gregory
