Request Review: 6902182: Starting with jdwp agent should not incur performance penalty
tom.deneau at amd.com
Tue Dec 15 12:59:02 PST 2009
the issues raised by Tom Rodriguez below have been addressed.
* there is now a common routine in graphKit.cpp called from both
GraphKit::builtin_throw and from parse2.cpp
* in parse2.cpp, it falls thru, if the uncommon trap is not taken
* uses local thread variable in the two runtime routines.
-- Tom D.
From: Thomas.Rodriguez at Sun.COM [mailto:Thomas.Rodriguez at Sun.COM]
Sent: Monday, December 14, 2009 6:51 PM
To: Deneau, Tom
Cc: hotspot-compiler-dev at openjdk.java.net
Subject: Re: Request Review: 6902182: Starting with jdwp agent should not incur performance penalty
On Dec 14, 2009, at 1:26 PM, Deneau, Tom wrote:
> New webrev is at http://cr.openjdk.java.net/~tdeneau/6902182/webrev.02/
> This rev changes
> * two places in the compiler where code for exception throws is
> being JITted (see parse2.cpp, graphKit.cpp). I was thinking the
> common code in these two should be extracted to one place but I
> wasn't sure whether that belonged in graphKit.cpp or in
GraphKit is base class containing most of the idiomatic code generation so you could put it there.
> * trace_exception in opto/runtime.cpp
> * exception_handler_for_pc_helper in c1/c1_Runtime1.cpp
In the two, why don't you use the thread that's in a local instead of calling JavaThread::current()?
In parse2.cpp why don't you just fall through instead of duplicating that code?
otherwise this looks good to me.
> Previously these places checked jvmti_can_post_exceptions() which only
> looked at whether the jvmti capabilities for exceptions were enabled,
> taking a slow path if true.
> Now they check a new flag JavaThread::_must_post_exception_events.
> This new flag is updated by calling jvmtiExport::must_post_exception_events
> whenever the jvmti situation for a thread might have changed.
> jvmtiExport::must_post_exception_events uses logic similar to that
> used by jvmtiExport::post_exception_throw and returns false if
> jvmtiExport::post_exception_throw wouldn't have done anything.
> I would appreciate it if someone familiar with the jvmti codepaths
> could review this to make sure that the must_post_exception_events
> flag is being updated in all the necessary places. Right now, it gets
> updated in
> * JavaThread::set_jvmti_thread_state
> * JvmtiEventControllerPrivate::recompute_enabled
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