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  1. JDK
  2. JDK-8276549

Improve documentation about ContainerPtr encoding

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    • gc
    • b24

      The documentation about the different CardSetPtr/CardSetContainers in g1CardSet.hpp line 187ff is, while correct, a bit outdated.

      The following facts are missing:
      - bitmaps are only used within Howl card set containers. It is almost never advantageous to use a bitmap over a whole region. Further, transferring cards from Howl to that "Full" bitmap is hard. The additional space used by the Howl array is negligible vs. a whole bitmap anyway.
      - The last two bits of the encoding for Howl (0b11) is assumed to be the same as the last two bits for "FullCardSet"; this has been done in various places to not be required to check for a "FullCardSet" first all the time in iteration code (only if there is a Howl card set container, that is fairly uncommon).

      Improve.

            tschatzl Thomas Schatzl
            tschatzl Thomas Schatzl
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