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  1. JDK
  2. JDK-8221732

Introduce CollectedHeap::hash_oop()

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    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 13
    • Fix Version/s: 13
    • Component/s: hotspot
    • Labels:
      None
    • Subcomponent:
      gc
    • Resolved In Build:
      b15

      Description

      The JVMTITagMap hashes oops by casts them to 32-bit unsigned integers. For ZGC, which has colored oop, this happens to work because all metadata bits are above 32-bit. In theory, ZGC could store its metadata bits in the lower 32-bit part of the address, in which case this hash scheme would break. Today we have an ugly assert in JvmtiTagHashmap::hash() to make sure this doesn't happen. However, the JVMITagMap should not make assumptions on what an oop looks like, and should instead delegate this hashing to CollectedHeap.

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            Assignee:
            pliden Per Liden
            Reporter:
            pliden Per Liden
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              Updated:
              Resolved: