RFR (XS): JDK-8204084: Remove the G1RSBarrierRegionFilter develop flag

Aleksey Shipilev shade at redhat.com
Wed May 30 10:15:21 UTC 2018


On 05/30/2018 12:08 PM, Thomas Schatzl wrote:
>   can I have reviews for this small change that removes the
> G1RSBarrierRegionFilter develop flag from G1 code that is implemented
> in a very incomplete way, and since I do not see a point fixing that I
> suggest removing it.
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8204084
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8204084/webrev/

Yup. Amusingly, this filter is implemented in shared C1 [1] and C2 [2] code, where the performance
does matter, and it is not hooked up to the flag :) It might indeed make little sense to perform
this filtering in arch-specific interpreter barriers.

I think you want to remove the comments like:

 273   // Does store cross heap regions?
 274   // It does if the two addresses specify different grain addresses.

 222   // Crosses regions, storing NULL?


-Aleksey

[1]
http://hg.openjdk.java.net/jdk/jdk/file/3831655869bc/src/hotspot/share/gc/g1/c1/g1BarrierSetC1.cpp#l151
[2]
http://hg.openjdk.java.net/jdk/jdk/file/3831655869bc/src/hotspot/share/gc/g1/c2/g1BarrierSetC2.cpp#l452

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