RFR (XS): 8200362: G1Mux2Closure should disable implicit oop verification

[Stefan Johansson]

Hi Thomas,

On 2018-03-28 17:27, Thomas Schatzl wrote:
> Hi all,
>
>    can I have reviews for this small change that fixes some annoyance
> when debugging with G1?
>
> In particular, G1Mux2Closure is used by verification to verify and in
> case of error print out g1 specific error messages.
>
> However, since G1Mux2Closure is an OopClosure, it is actually wrapped
> by NoHeaderExtendedOopClosure in oop_iterate* calls. ExtendedOopClosure
> has its own verification that is very generic, and may trigger in the
> same situations as G1Mux2Closure.
>
> Disable this implicit verification for G1Mux2Closure so that we always
> get the g1 specific error messages.
>
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8200362
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8200362/webrev/
Nice change, always good to get detailed information. I think you need 
to change the code using the G1Mux2Closure as well. On line 666 in 
heapRegion.cpp:
   G1Mux2Closure mux(&vl_cl, &vr_cl);
   obj->oop_iterate_no_header(&mux);
This should now be a normal oop_iterate(&mux) to make sure the right 
verification is done.

Thanks,
Stefan


> Testing:
> (mostly finished) hs-tier 1+2
>
> Thanks,
>    Thomas
>