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  1. JDK
  2. JDK-8221732

Introduce CollectedHeap::hash_oop()

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    • Enhancement
    • Resolution: Fixed
    • P4
    • 13
    • 13
    • hotspot
    • None
    • gc
    • 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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              Created:
              Updated:
              Resolved: