RFE: 4508774: Implementation for GetOperandStack

serguei.spitsyn at oracle.com serguei.spitsyn at oracle.com
Mon Feb 10 15:36:58 PST 2014

Hi Jan,

Thank you for contributing a suggested fix for this enhancement!
I've attached your diff into the bug report file getOpStack.patch.
Of course, we will take care and make sure the final fix is type safe.

In case the attachment was removed from the mailing list.
Here is an external link to the diff:

The above link is helpful as your original diff was removed from the email.


On 2/10/14 9:21 AM, Jan Siersch wrote:
> Hi all,
> this post is about a feature request for JVMTI to allow access to the 
> operand stack:
> https://bugs.openjdk.java.net/browse/JDK-4508774
> As part of a project I'm working on, I have implemented a set of 
> functions, namely GetOperand<Type>, which provide the requested 
> functionality, and I would like to provide this implementation to the 
> OpenJDK project. As I am not a regular contributor to the OpenJDK 
> project, I do not have an account for the bug tracker and cannot post 
> my code there.
> I have attached a diff with the modified hotspot source code to this 
> e-mail. This implementation adds a new function category "Operand 
> Stack" to JVMTI that contains 5 functions (GetOperandObject, 
> GetOperandInt, GetOperandLong, GetOperandFloat, GetOperandDouble) 
> which can be used the same way as the corresponding GetLocal<Type> 
> functions.
> All changes to the source files are purely additive. No existing 
> functions are modified. One new VM Operation "GetOperand" is added and 
> implemented. The changes are based on the "JDK 7 Updates Master" 
> branch. I have compiled OpenJDK locally with these changes and had no 
> problems with them.
> However this implementation still has one drawback: the functions are 
> not type-safe, as I was unable to find the necessary information 
> within hotspot to do proper type-checking of operands. For me this is 
> not a problem, because in my project I have a way of inferring operand 
> types externally, but for proper production code type-checking should 
> be added (there is a FIXME in the added source for this purpose).
> I hope someone reading this list has the time to look at this code and 
> if they find it suitable, to integrate it into the OpenJDK project. 
> About licensing: you may use this code in whatever way, shape or form 
> you see fit.
> Regards,
> Jan

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