Hi Daniil,

It'd be nice if Chris has a chance to look at this fix.
He has most recent experience in this area.

Thanks,
Serguei


On 1/17/19 6:08 PM, Daniil Titov wrote:
Please review the change that fixes JDB stepping issue for a specific case when the 
single step request was initiated earlier in the stack, previous calls were for 
methods in the filtered classes (single stepping was disabled), 
handleMethodEnterEvent() re-enabled stepping and the first bytecode upon entering the 
current method requires resolving constant pool entry. In this case the execution 
resumes in java.lang.Classloader.loadClass() and since it is also a filtered class 
the single stepping is getting disabled again (stepControl.c :593).  When loadClass() 
exits a notifyFramePop() is called on the loadClass() frame but due to condition 
fromDepth >= afterPopDepth  at stepControl.c :346 (that doesn't hold in this case, 
in this case fromDepth is 1 and afterPopDepth  is 4) the notifyFramePop() fails to 
enable single stepping back. The fix removes the excessive condition fromDepth >= 
afterPopDepth  in notifyFramePop() method (stepControl.c:346)  to ensure that when a 
method cal!
  led from the stepping frame (and during which we had stepping disabled) has 
returned the stepping is re-enabled to continue  instructions steps in the 
original stepping frame.

Webrev: http://cr.openjdk.java.net/~dtitov/8163127/webrev.01
Bug: https://bugs.openjdk.java.net/browse/JDK-8163127

Thanks!
--Daniil




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