Re: JVMTI_ERROR_INVALID_SLOT error after using AdviceAdapter.onMethodEnter

You are right, this really is a better way. Implemented it already:

- in visitMethod I get the argument types (if any) and calculate the index
of the first local variable that would come after "this" (for instance
methods) AND potential arguments (considering their type sizes)
- in onMethodEnter I visit a new Label followed by the invokestatic
- in visitLocalVariable I now check if the index of the var is smaller than
the calculated index above. If so I know I'm dealing with "this" or
arguments and will use the new label as start

Thanks a lot and sorry for not spotting that earlier. Was surprised to see
this behaviour and wasn't sure if ASM behaves the way it should in this
case.

BTW: I just reproduced the problem with a debugger as well:

- Write a simple agent that onMethodEnter adds something (e.g. a call to a
static method)
- Using Eclipse set a breakpoint on the line where method signature is
declared (*not the first line of code in the method's body*)

If you start the program in debug mode you will get the same error I ran
into:
com.sun.jdi.InternalException: Got error code in reply: 35 occured
retrieving 'this' frm stack frame

If you continue debugging everything will appear as expected in the
variables view, etc.

I guess not many people will have this problem, but whoever runs into this
definitely needs to adjust the positions.

Thanks again!

2018-02-08 11:55 GMT+01:00 Eliot Moss <[email protected]>:

> Sorry for the series of emails ...
>
> The ASM docs describe how the local variable and line number information
> can (should, in this case) be visited related to adding labels.  You
> would add a label at the beginning, before adding the invokestatic,
> visit the label and then be in a position to update the local var and
> line number information properly.  See Section 4.3 of the ASM 4 guide.
>
> Cheers - EM
>
>
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